阅读说明：本技术 利用可调等离子体电势的可变模式等离子体腔室 (Variable mode plasma chamber using adjustable plasma potential ) 是由 S·E·萨瓦 马绍铭 于 2020-07-16 设计创作，主要内容包括：提供了等离子体处理设备和相关方法。在一个示例中,等离子体处理设备可以包括被配置为能够保持等离子体的等离子体腔室。该等离子体处理设备可以包括形成该等离子体腔室的壁的至少一部分的介电窗。该等离子体处理设备可以包括位于该介电窗附近的感应耦合元件。该感应耦合元件可以被配置为当用射频(RF)能量供能时在该等离子体腔室中由该工艺气体产生等离子体。该等离子体处理设备可以包括具有被配置为支撑工件的工件支撑件的处理腔室。该等离子体处理设备可以包括位于该感应耦合元件与该介电窗之间的静电屏蔽体。该静电屏蔽体可以经由可调电抗阻抗电路接地到接地参考。(Plasma processing apparatus and related methods are provided. In one example, a plasma processing apparatus may include a plasma chamber configured to be capable of holding a plasma. The plasma processing apparatus may include a dielectric window forming at least a portion of a wall of the plasma chamber. The plasma processing apparatus can include an inductive coupling element positioned proximate the dielectric window. The inductive coupling element can be configured to generate a plasma from the process gas in the plasma chamber when energized with Radio Frequency (RF) energy. The plasma processing apparatus may include a process chamber having a workpiece support configured to support a workpiece. The plasma processing apparatus can include an electrostatic shield positioned between the inductive coupling element and the dielectric window. The electrostatic shield may be grounded to a ground reference via an adjustable reactive impedance circuit.)

1. A plasma processing apparatus, comprising:

a plasma chamber configured to be capable of holding a plasma;

a dielectric window forming at least a portion of a wall of the plasma chamber;

a gas source configured to provide a process gas to the plasma chamber;

an inductive coupling element positioned proximate to the dielectric window, the inductive coupling element configured to generate a plasma from the process gas in the plasma chamber when energized with Radio Frequency (RF) energy;

a process chamber having a workpiece support configured to support a workpiece, the process chamber in fluid communication with the plasma chamber;

an electrostatic shield positioned between the inductive coupling element and the dielectric window, the electrostatic shield having a parasitic capacitance to a ground reference and being grounded to the ground reference via an adjustable reactive impedance circuit configured to adjust a range of reactance between the electrostatic shield and the ground reference between a capacitive reactive condition and an inductive reactive condition at a frequency of RF energy provided to the inductive coupling element; and is

Wherein the reactance range includes an inductive reactance sufficient to achieve a parallel resonance condition with a parasitic capacitance between the electrostatic shield and a ground reference.

2. The plasma processing apparatus of claim 1, further comprising a plurality of dielectric confinement elements, wherein at least two of the plurality of dielectric confinement elements are separated by a gap, wherein the width of the gap is less than about 1 cm.

3. The plasma processing apparatus of claim 2 wherein the plurality of dielectric confinement elements comprises a plurality of dielectric chamber liners mounted substantially parallel to a grounded sidewall of the process chamber.

4. The plasma processing apparatus of claim 1, further comprising a baffle structure positioned between the plasma chamber and the process chamber, wherein the baffle structure has a diameter in a range of about 10% to about 70% of a diameter of the plasma chamber, wherein the baffle structure is configured to absorb one or more charged species from the plasma.

5. The plasma processing apparatus of claim 4 wherein a center of the baffle structure is located above a substantial center of the workpiece support.

6. The plasma processing apparatus of claim 1, wherein the adjustable reactive impedance circuit comprises an inductor and a variable capacitor connected in series, the inductor having greater than 1/(ω) for a frequency ω of energy supplied to the inductive coupling element²C_s) An inductance value of, and C_sIs the parasitic capacitance between the electrostatic shield and the ground reference.

7. The plasma processing apparatus of claim 1 further comprising a second adjustable reactive impedance circuit coupled between the electrostatic shield and the inductive coupling element, the second adjustable reactive impedance circuit configured to adjust a reactance between the inductive coupling element and the electrostatic shield between a condition of capacitive reactance and a condition of inductive reactance at a frequency of RF energy provided to the inductive coupling element.

8. A plasma processing apparatus, comprising:

a plasma chamber configured to be capable of holding a plasma;

a dielectric window forming at least a portion of a wall of the plasma chamber;

a gas source configured to provide a process gas to the plasma chamber;

an inductive coupling element positioned proximate to the dielectric window, the inductive coupling element configured to generate a plasma from the process gas in the plasma chamber when energized by Radio Frequency (RF) energy;

a process chamber having a workpiece support configured to support a workpiece, the process chamber in fluid communication with the plasma chamber;

an electrostatic shield positioned between the inductive coupling element and the dielectric window, the electrostatic shield having a parasitic capacitance to the inductive coupling element; and

an adjustable reactive impedance circuit coupled between the inductive coupling element and the electrostatic shield, the adjustable reactive impedance circuit configured to adjust a reactance between the inductive coupling element and the electrostatic shield between a capacitive reactive condition and an inductive reactive condition at a frequency of RF energy provided to the inductive coupling element;

wherein the adjustable reactive impedance circuit is operable to achieve an inductive reactance that is at least approximately equal to a capacitive reactance of the parasitic capacitance.

9. The plasma processing apparatus of claim 8 wherein the adjustable reactive impedance circuit comprises an inductor and a variable capacitor, wherein inductor has approximately b/(ω) and²*C_A) Where ω is the frequency of the RF energy supplied to the inductive coupling element, C_AIs a parasitic capacitance between the inductive coupling element and the electrostatic shield, and b is a constant greater than about 1.01.

10. The plasma processing apparatus of claim 9 wherein the variable capacitor has a range that enables the adjustable reactive impedance circuit to achieve a series resonance condition between an inductive coupling element and the electrostatic shield.

11. The plasma processing apparatus of claim 8, further comprising a baffle structure configured to absorb one or more charged species from the plasma.

12. The plasma processing apparatus of claim 8, further comprising a plurality of dielectric confinement elements, wherein at least two of the plurality of dielectric confinement elements are separated by a gap, wherein the width of the gap is less than about 1 cm.

13. The plasma processing apparatus of claim 12 wherein the plurality of dielectric confinement elements comprises a plurality of dielectric chamber liners mounted substantially parallel to a grounded sidewall of the process chamber.

14. The plasma processing apparatus of claim 11, wherein the baffle structure is located between the plasma chamber and the process chamber, wherein the baffle structure has a diameter in a range of about 10% to about 70% of a diameter of the plasma chamber.

15. The plasma processing apparatus of claim 14 wherein a center of the baffle structure is located above a substantial center of the workpiece support.

16. A plasma processing apparatus, comprising:

a plasma chamber configured to be capable of holding a plasma;

a dielectric window forming at least a portion of a wall of the plasma chamber;

a gas source configured to provide a process gas to the plasma chamber;

an inductive coupling element positioned proximate to the dielectric window, the inductive coupling element configured to generate a plasma from the process gas in the plasma chamber when energized by Radio Frequency (RF) energy;

a process chamber having a workpiece support configured to support a workpiece, the process chamber in fluid communication with the plasma chamber;

an electrostatic shield positioned between the inductive coupling element and the dielectric window, the electrostatic shield being grounded via a first adjustable reactive impedance circuit configured to have a reactance that is adjustable in a range from an inductive reactance to a capacitive reactance; and

a second adjustable reactive impedance circuit coupled between the inductive coupling element and the electrostatic shield, the second adjustable reactive impedance circuit configured to have a reactance that is adjustable over a range from an inductive reactance to a capacitive reactance.

17. The plasma processing apparatus of claim 16 wherein the first adjustable reactive impedance circuit is operable to achieve a parallel resonance condition with a parasitic capacitance between the electrostatic shield and the ground reference.

18. The plasma processing apparatus of claim 17 wherein the first adjustable reactive impedance circuit comprises an inductor and a variable capacitor coupled in series, wherein the variable capacitor has a range operable to achieve a series resonance condition with the inductor in the first adjustable impedance circuit at a frequency of the RF energy provided to the inductive coupling element.

19. The plasma processing apparatus of claim 16 wherein the second adjustable reactive impedance circuit is operable to achieve a parallel resonance condition with a parasitic capacitance between the inductive coupling element and the electrostatic shield at a frequency of the RF energy provided to the inductive coupling element.

20. The plasma processing apparatus of claim 16 wherein the second adjustable reactive impedance circuit is operable to achieve a net capacitive reactance between the inductive coupling element and the electrostatic shield of less than about 50 ohms at the frequency of the RF energy provided to the inductive coupling element.

Technical Field

The present disclosure generally relates to plasma processing using a plasma source.

Background

Plasma processing tools can be used in the manufacture of devices such as integrated circuits, micromechanical devices, flat panel displays, and other devices. Plasma processing tools used in modern plasma etch applications need to provide high plasma uniformity and multiple plasma controls, including independent plasma distribution, plasma density, and ion energy control. In some cases, plasma processing tools may require a stable plasma to be maintained in various process gases and under various conditions (e.g., gas flow, gas pressure, etc.).

Disclosure of Invention

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

One example aspect of the present disclosure relates to a plasma processing apparatus. The plasma processing apparatus may include a plasma chamber configured to be capable of holding a plasma. The plasma processing apparatus may include a dielectric window forming at least a portion of a wall of the plasma chamber. The plasma processing apparatus may include a gas source configured to supply a process gas to the plasma chamber. The plasma processing apparatus can include an inductive coupling element positioned proximate the dielectric window. The inductive coupling element can be configured to generate a plasma from the process gas in the plasma chamber when energized with Radio Frequency (RF) energy. The plasma processing apparatus may include a process chamber having a workpiece support configured to support a workpiece. The processing chamber may be in fluid communication with the plasma chamber. The plasma processing apparatus can include an electrostatic shield positioned between the inductive coupling element and the dielectric window. The electrostatic shield may be grounded to a ground reference via an adjustable reactive impedance circuit. The electrostatic shield may have a parasitic capacitance to the ground reference. The adjustable reactive impedance circuit may be configured to adjust a range of reactance between the electrostatic shield and the ground reference between a capacitively-reactive condition and an inductively-reactive condition at a frequency of the RF energy provided to the inductive coupling element. The reactance range may include an inductive reactance sufficient to achieve a parallel resonance condition with a parasitic capacitance between the electrostatic shield and the ground reference.

Variations and modifications may be made to the example embodiments of the present disclosure.

These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

Drawings

A full and enabling disclosure of one of ordinary skill in the art is set forth more particularly in the remainder of the specification, including reference to the accompanying figures wherein:

fig. 1 depicts an example plasma processing apparatus according to an example embodiment of the present disclosure;

fig. 2 depicts an example equivalent circuit of a plasma processing apparatus according to an example embodiment of the present disclosure;

fig. 3 depicts an example equivalent circuit of a plasma processing apparatus according to an example embodiment of the present disclosure;

FIG. 4 depicts a flowchart of an example method according to an example embodiment of the present disclosure;

FIG. 5 depicts an example plasma processing apparatus according to an example embodiment of the present disclosure;

FIG. 6 depicts an example plasma processing apparatus according to an example embodiment of the present disclosure;

FIG. 7 depicts an example plasma processing apparatus according to an example embodiment of the present disclosure; and

fig. 8 depicts an example plasma processing apparatus according to an example embodiment of the present disclosure.

Detailed Description

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Example aspects of the present disclosure relate to plasma processing apparatuses and related methods. The plasma processing apparatus may include one or more inductive coupling elements (e.g., coils) for inducing an inductive plasma within a plasma chamber for processing a workpiece (e.g., performing a dry etch process or a dry strip process). The one or more inductive coupling elements may be disposed adjacent a dielectric window (e.g., a dielectric wall) forming a portion of the plasma chamber. The one or more inductive coupling elements may be energized with Radio Frequency (RF) energy to induce a plasma that is at least partially induced in a process gas in the plasma chamber. The plasma processing apparatus can include an electrostatic shield (e.g., Faraday shield) disposed between the one or more inductive coupling elements (e.g., antennas or coils) and the dielectric window. The electrostatic shield is structured to have a free space or air gap capacitance, C, to the inductive coupling element_A. The C is_AMay depend on the dimensions of the electrostatic shield and the inductive coupling element and the proximity between the electrostatic shield and the inductive coupling element. In addition, there may be parasitic capacitance including free space or air gap capacitance of the electrostatic shield to the grounded enclosure of the inductive coupling element and to other grounded components of the chamber, C_S. Likewise, there may be free space or air gap capacitance, C, from the ceiling of the plasma chamber to the enclosure and to other grounded components of the chamber_T-G. The enclosure may be an RF enclosure (e.g., an RF cage) configured to reduce electromagnetic interference radiation into the surrounding environment.

According to example aspects of the present disclosure, the electrostatic shield may be connected to the inductive coupling element by a circuit having an adjustable reactive impedance and/or may be grounded by a circuit having an adjustable reactive impedance. In some embodiments, the plasma processing apparatus can include a voltage sensor configured to measure a radio frequency component of the RF voltage of the electrostatic shield. In some example embodiments, the plasma processing apparatus may include a controller that adjusts the reactance from the electrostatic shield to ground and from the inductive coupling element to the electrostatic shield by adjusting one or more variable capacitors in a circuit connecting the electrostatic shield to the inductive coupling element and/or the electrostatic shield to ground. These may be adjusted to maintain the capacitance value according to a scheme that specifies the capacitance value. Further, there may be circuitry connecting the voltage sensor to the controller such that the controller can monitor the RF voltage of the electrostatic shield and thereby adjust the capacitor to control the RF voltage of the electrostatic shield according to a preprogrammed schedule that can specify the RF voltage of the electrostatic shield. Thus, by adjusting the adjustable reactive impedance of the circuit connecting the electrostatic shield to ground and/or the adjustable reactive impedance of the circuit connecting the electrostatic shield to the inductive coupling element, the RF voltage of the electrostatic shield can be maintained at a desired setpoint voltage.

In some cases, it is difficult to remove a particular type of material from a workpiece (e.g., a substrate, a silicon wafer, or a thin film). Examples of difficult to remove materials may include photoresists, organic materials, materials with hardened surface layers or surface compositions that interfere with isotropic, reactive free radical based removal, stripping, and/or etching processes. In addition, it is difficult for an etch chamber to etch a thin film in such a way that the anisotropy of the etch process can vary significantly and in a controlled manner during the etch process. It may also be difficult for an etch chamber having ion assisted processing capabilities to further provide isotropic etching at high rates, for example, greater than about 1000 nanometers (nm) per minute. Furthermore, it can be difficult to provide a processing chamber configured to provide very low ion bombardment energy (e.g., below about 5eV) in some portions of the etching process, such that the ion bombardment is effectively isotropic, and in other portions of the process, at much higher ion energies, sufficient to make the ion bombardment anisotropic and thereby orient the etching process.

Example aspects of the present disclosure relate to a plasma processing apparatus that may include an inductively coupled plasma source having an electrostatic shield (e.g., Faraday shield) connected to electrical ground through a first tunable, substantially reactive impedance. In some embodiments, the electrostatic shield may also be connected to the inductive coupling element through a second and independently adjustable reactive impedance for additional control of the RF voltage on the electrostatic shield. The plasma processing apparatus may be used for processing semiconductor wafers, in particular performing etch, strip or plasma enhanced chemical vapor deposition (PEVCD) processes. The plasma processing apparatus can include a controller to set and control the reactive impedance prior to and/or during processing of the workpiece. The controller may include sensors and circuitry to measure the RF voltage of the electrostatic shield and provide the measured voltage value to the controller such that the first and second reactive impedances may be adjusted such that the measured voltage of the electrostatic shield approaches a desired set point within a particular period or step in the plasma process. In some embodiments, the controller may measure the RF voltage on the inner surface of the electrostatic shield at one or more locations proximate to the dielectric window. In some embodiments, the electrostatic shield may include a plurality of shield plates. A sensor connected to the controller may measure the RF voltage at one or more locations on the surface of the shield plate.

In some embodiments, the first adjustable reactive impedance of the circuit that connects the electrostatic shield to ground may be effectively in parallel with a parasitic capacitance of the electrostatic shield to ground. The parasitic capacitance C_SThere may be a parallel combination of capacitance from the electrostatic shield through any dielectric spacer or barrier and from the air gap capacitance of the electrostatic shield to the capacitance of the processing chamber wall and RF shield enclosure for the inductive coupling element. Varying capacitance-effectively and parasitic capacitance C in a first tunable reactive impedance circuit_SParallel-the magnitude and sign of the total reactive impedance between the electrostatic shield and ground can be varied over a considerable range (e.g. positive for inductance and negative for capacitance). In some embodiments, the RF voltage amplitude of the electrostatic shield may be less than about 2V by varying the capacitance in the first adjustable reactive impedance circuit_RMS(e.g., for impedance values of less than about 10 ohms or less) to greater than about 50V_RMS(e.g., for large impedance values in excess of about 100 ohms).

During operation of the plasma source (e.g., inductive coupling element, etc.), the RF magnetic field from the inductive coupling element may pass through an opening or gap in the electrostatic shield member and through the dielectric wall to generate an induced electric field within the plasma chamber to sustain the plasma. In some examples, the capacitive field from the electrostatic shield and the ceiling of the plasma chamber generally does not contribute more than a small percentage to the power input to the plasma. Due to a considerable free space or air gap parasitic capacitance C from the inductive coupling element to the electrostatic shield_AThere may typically be some RF current from the inductive coupling element to the electrostatic shield. The RF current picked up by the electrostatic shield may then pass through the dielectric wall via the capacitance C_S-PFlowing to the plasma, through a tunable impedance to ground, or through the free-space capacitance C of the electrostatic shield_STo the grounded enclosure and grounded components of the chamber.

According to example aspects of the present disclosure, because the electrostatic shield is proximate to a dielectric wall of the plasma chamber, the RF voltage on the electrostatic shield may be capacitively coupled through the wall (via C)_S-P) To the plasma, which conducts RF current to the plasma. As a result, there may be a substantially proportional relationship between the RF voltage of the electrostatic shield and the RF plasma potential within the plasma chamber. In some implementations, the capacitance C is based on_AAnd C_S-PVarying the first reactive circuit, the accessible value of the RF voltage of the electrostatic shield is such as to allow at about 2V_RMSAnd about 50V_RMSThe plasma potential is adjusted. Thus, the RF voltage, and thus the RF plasma potential, on the electrostatic shield can be adjusted to a reasonably wide range for the steps specified by the recipe in the desired plasma process.

According to an example aspect of the present disclosure, in some embodiments, by additionally having a second adjustable reactive impedance circuit that in some embodiments contains both an inductor and a variable capacitor connecting an inductive coupling element to an electrostatic shield, the electrostatic shield has an RF voltage range that is comparable to that of an electrostatic shield without the second adjustable reactive circuitThe RF voltage range above can be further increased significantly. For example, in some embodiments, the second reactive impedance circuit may increase the RF voltage of the electrostatic shield (e.g., the maximum shielded RF voltage achieved by only the first reactive circuit) by tuning a variable capacitor in the circuit such that the capacitive reactance dominates the inductive reactance of an inductor in the circuit. Capacitive coupling with air gap C_AThe resulting net capacitive reactance of the parallel second reactive impedance circuit may increase the RF current from the inductive coupling element to the electrostatic shield. And a capacitor C passing through the air gap_AThe increased RF current in phase may increase the net total RF current from the inductive coupling element to the electrostatic shield and the RF voltage on the electrostatic shield. In some embodiments, the RF current flowing to the electrostatic shield may be increased (e.g., maximized) by tuning a capacitor in the second adjustable reactance circuit to resonate in series with the inductor to provide a substantially increased total RF current from the inductive coupling element to the electrostatic shield. In some embodiments, the RF current to the shield may be increased by tuning a capacitor in the second reactive impedance circuit to have a capacitive reactance that is greater than or equal to an inductive reactance of an inductor in the second reactive impedance circuit. In this way, the RF voltage on the electrostatic shield can be easily increased to greater than about 100V_RMSEven up to about 200V_RMSThis enables the RF plasma potential to exceed about 50V_RMSEven up to about 100V_RMS。

In some embodiments, the second adjustable reactive impedance circuit may substantially reduce the shielding RF voltage. For example, a first adjustable reactive impedance circuit connecting the electrostatic shield to ground may be tuned to have a very low net reactance, while a second adjustable reactive impedance circuit may be tuned to have a parallel resonance condition with an air gap capacitance between the electrostatic shield and the inductive coupling element. This parallel resonance of the second circuit may result in a substantial cancellation of the RF (displacement) current from the inductive coupling element to the electrostatic shield, thereby reducing the electrostatic shield RF voltage to about 1V_RMSOr the following. Thus, a second adjustable reactive impedance circuit having such an impedance range and being independent of the first reactive circuit may be added to achieveAnd thus increases the flexibility and capability of the processing chamber.

In some embodiments, the second adjustable reactive impedance circuit alone may be used to increase or decrease the shielded RF voltage range without the first adjustable reactive impedance circuit. For example, in some embodiments, the second reactive impedance circuit may increase the shielding RF voltage by tuning a variable capacitor in the circuit such that the capacitive reactance dominates the inductive reactance of an inductor in the circuit. In some embodiments, the RF current to the electrostatic shield may be further increased by tuning a capacitor in the second adjustable reactance circuit to be in series resonance with the inductor to provide a substantially increased total RF current flowing from the inductive coupling element to the electrostatic shield. In some embodiments, the second adjustable reactive impedance circuit may be tuned to be in parallel resonance with an air gap capacitance between the electrostatic shield and the inductive coupling element to substantially reduce a net RF current to the shield and a shield RF voltage.

In some embodiments, the plasma may extend to a volume adjacent the workpiece support pedestal for a range of first and/or second adjustable reactive impedance circuit conditions for which the RF plasma potential is sufficiently large. When the workpiece support pedestal is constructed of a conductive material and has a low electrical impedance to ground (e.g., less than about 10 ohms) over some set range of adjustable impedance from the electrostatic shield to ground, there may be a space charge sheath having an RF voltage amplitude between the plasma and the workpiece support pedestal of more than about 10 volts such that ions from the plasma above the pedestal may be accelerated by an electric field in the sheath to bombard a workpiece supported on the pedestal. When the RF plasma potential is greater than about 50 volts amplitude (e.g., about 35V)_RMS) When used, ions may have large energies (e.g., maximum energies) greater than about 20 electron volts (eV) or more, such that the ions may participate in accelerating or controlling an etch or PEVCD process on a workpiece. In some embodiments, the plasma potential above the susceptor may be a function of the ratio of the surface area of the electrostatic shield to the surface area of the susceptor and surrounding metal chamber walls. By confining the plasma volume to a small plasma volume (e.g., blanketing)The minimum plasma volume required for the workpiece), the ratio of the shield surface area to the ground wall area may be greater than about 1, and the sheath potential above the workpiece may be greater than the sheath potential at the dielectric wall within the electrostatic shield. This helps to reduce sputtering from the dielectric wall and to increase the ion energy bombarding the workpiece (e.g., substrate or wafer).

One example aspect of the present disclosure relates to a plasma processing apparatus. The plasma processing apparatus may include a plasma chamber, a dielectric window or wall forming at least a portion of the plasma chamber, an inductive coupling element positioned proximate the dielectric window, an electrostatic shield interposed between the dielectric wall and the inductive coupling element and grounded by a first adjustable reactive impedance circuit having an adjustable impedance, a second adjustable reactive impedance circuit connecting the electrostatic shield to the inductive coupling element, a voltage sensor measuring an RF voltage of the electrostatic shield, and a controller configured to adjust the RF voltage of the electrostatic shield by adjusting reactive impedances of the first adjustable reactive impedance circuit and the second adjustable reactive impedance circuit. The electrostatic shield has a total capacitance C due to significant air gap or free space capacitance between the electrostatic shield and the workpiece processing chamber, and air gap or free space parasitic capacitance between the electrostatic shield and the enclosure for the plasma chamber_SA first adjustable reactive impedance circuit connecting the electrostatic shield to ground may be combined in parallel with the combined free space capacitance of the electrostatic shield to ground, giving a wide range of net reactive impedances between the electrostatic shield and ground. In some embodiments, the reactance range of the first reactance circuit may include C and C_SAnd series resonance of a capacitor and an inductor within the first adjustable reactive impedance circuit. This reactance range of the first reactance circuit may result in a wider adjustable range of the RF voltage across the electrostatic shield. In some embodiments, the reactance range of the second reactance circuit may include C and C_AAnd series resonance of a capacitor and an inductor within the second adjustable reactive impedance circuit. This reactance range of the second reactive circuit may result in a wider tuning range of the total impedance between the inductive coupling element and the electrostatic shield.

In some embodiments, the electrostatic shield is connected to an electrically grounded in-air or free-space parasitic capacitance C_SMay be between about 20 picofarads and about 2000 picofarads, which does not include any circuitry to ground the electrostatic shield. In some embodiments, C_SCan range from about 50pf to about 1000 pf. In some embodiments, the first adjustable reactive impedance circuit from the electrostatic shield to ground may be coupled to a parasitic capacitance C_SA parallel circuit. In some embodiments, the first adjustable reactive impedance circuit may comprise an inductor L₁And a variable capacitor C₁In a series combination. The inductor L can be selected₁Inductance range and capacitor C₁To achieve L₁And C₁And a combined part L₁+C₁Parasitic capacitance C to ground of electrostatic shield_SIs resonant in parallel. Inductor L₁May be larger than the parasitic capacitance (free space plus by any dielectric insulation) C between the electrostatic shield and ground_SThe magnitude of the reactance of. Variable capacitor C₁May have a first reactance magnitude (e.g., a maximum reactance magnitude) and a second reactance magnitude (e.g., a minimum reactance magnitude), the first reactance magnitude being slightly greater (e.g., greater than about 10%) than L₁The magnitude of the inductive reactance of (a), the magnitude of the second reactance being sufficiently small so as to be sufficiently small when measured from L₁The second reactance magnitude may result in a net inductive reactance of the first circuit that is slightly greater than the reactance magnitude of the free-space capacitance between the electrostatic shield and the ground reference (| Xc | ═ 1/[ ω C ]) when subtracted by the second reactance magnitude_S]). The latter parallel resonance condition may allow partial or complete cancellation of the passage of C from the electrostatic shield_SRF current to ground, thereby increasing the electrostatic shield RF voltage and the RF voltage range to which the electrostatic shield can be tuned. In some embodiments, the variable capacitor in the first reactive impedance circuit between the electrostatic shield and ground may be a simple two-position capacitor, where one position is the low impedance of the first reactive circuit and the other position is the and C_SNear parallel resonance, a high total impedance of the shield to ground is created, so that it can be realized more economicallyTuning of the electrostatic shield RF voltage at a given power level. According to example aspects of the present disclosure, an inductive coupling element of a plasma processing apparatus may generate a plasma in a plasma chamber when energized with RF energy. The RF plasma potential can be controlled at multiple levels. Such a plasma processing apparatus and associated method are useful for various applications.

In some embodiments, the in-air or free-space parasitic capacitance (C) of the inductive coupling element to the electrostatic shield_A) May be between about 5 picofarads and about 1000 picofarads. In some embodiments, C_ACan range from about 20pf to about 500 pf. In some embodiments, the second adjustable reactive impedance circuit from the electrostatic shield to the inductive coupling element may include an inductor and a variable capacitor connected in series. The inductor L can be selected₂Inductor and capacitor C₂To achieve L₂And C₂And the parasitic capacitance C of the combined component and electrostatic shield to the inductive coupling element_AIs resonant in parallel. Inductor L₂Can be between the electrostatic shield and the inductive coupling element (free space plus any dielectric insulation) and a capacitance C_ABetween one and two times the magnitude of the reactance of (c). The variable capacitor may have a value slightly greater than L₂A first reactance magnitude (e.g., a maximum reactance magnitude) of a magnitude of the inductive reactance of (a). The variable capacitor may have a second reactance magnitude (e.g., minimum reactance magnitude) small enough such that when taken from L₂When subtracted, it produces a net reactance that is slightly larger than the reactance magnitude of the free space capacitance between the electrostatic shield and the coil (| Xc | ═ 1/[ ω C |)_A]). Likewise, for the second reactive circuit, a parallel resonance condition may be achieved that allows for effectively canceling the RF current flowing from the inductive coupling element to the electrostatic shield, thereby reducing the RF current shunted to the electrostatic shield and reducing the lower limit of the RF voltage range to which the electrostatic shield may be tuned. In some embodiments, the variable capacitor in the second reactive impedance circuit between the electrostatic shield and the inductive coupling element may be incorporated into the impedance matching network housing,and the grounding of the first reactive circuit from the electrostatic shield, makes tuning of the electrostatic shield RF voltage at a given power level more economically achievable. According to example aspects of the present disclosure, an inductive coupling element of a plasma processing apparatus may generate a plasma in a plasma chamber when energized with RF energy. The RF plasma potential can be controlled to a wide range of levels that can be used for any step of one or more processes.

In some embodiments, the inductive coupling element (e.g., an antenna or coil for an inductively coupled plasma source) may be powered by an automatically controllable RF electrical power source that provides RF current to flow through the inductive coupling element. The workpiece support pedestal may be located within the exhaust chamber and/or within and/or adjacent to the plasma generated by the inductive coupling element. The dielectric window may be a dielectric wall forming at least a portion of the plasma chamber. The electrostatic shield may be a slotted electrostatic shield interposed between the inductive coupling element and the dielectric wall. The electrostatic shield may be connected to electrical ground through an adjustable, substantially reactive first reactive impedance circuit. In some embodiments, the electrostatic shield may have a plurality of plates of conductive material commonly grounded by a first automatically adjustable reactive impedance circuit, and the plates may be separated from each other by a gap having a width of between about 2 millimeters (mm) and about 3 centimeters. Such a gap may have a long direction substantially perpendicular to the direction of current flow in the inductive coupling element. The configuration of the plates and gaps may be such that direct electrostatic coupling (capacitance) between the inductive coupling element and the inner surface of the dielectric wall may be reduced by at least about a factor of two or more.

In some embodiments, the electrostatic shield may be connected to a conductive top cover of the plasma chamber such that the conductive top cover may conduct RF current to/from the plasma generated by the inductive coupling element directly or through a thin dielectric liner that may be adjacent to an inner surface of the top cover. In some embodiments, the conductive cap may be positioned adjacent to a top of the dielectric wall. In some embodiments, the controller may control the voltage level by adjusting the total impedance (including parasitic capacitance C) from the electrostatic shield to ground_S+C_T-G(because of C)_SAnd C_T-GThe combination is a parallel capacitance from the shield and the top cap to ground)) is adjusted from about 1 ohm to about 100 ohms or more in parallel with the first adjustable reactive impedance circuit and the total impedance from the inductive coupling element to the electrostatic shield (including parasitic capacitance C)_AAnd a second adjustable reactive impedance circuit) from less than about 50 ohms to greater than about 200 ohms to adjust the RF voltage of the electrostatic shield, and thereby the voltage of the top cover, in a range from an amplitude of less than about 5V to an amplitude of about 500V.

In some embodiments, the controller may include circuitry (e.g., connected to a voltage sensor or detector) to measure the RF voltage at a location on the one or more shield plates or housing forming the electrostatic shield proximate the inductive coupling element. The circuit may provide data indicative of this measured RF voltage to the controller to enable the controller to adjust the reactive impedance of the first circuit between the electrostatic shield and ground as part of a closed loop control system. In some embodiments, the controller may adjust an impedance of a second variable reactance circuit connecting the inductive coupling element to the electrostatic shield as part of a closed loop control system. In some embodiments, the controller may adjust the reactive impedance of the first and second reactive impedance circuits to adjust the RF voltage on the electrostatic shield for a particular process step to provide a desired level of ion bombardment for that process step. In some embodiments, the controller may adjust the impedance of the first and second reactive circuits such that the RF voltage on the electrostatic shield may be reduced (e.g., minimized) such that ion bombardment of the workpiece according to a particular process step is reduced (e.g., minimized). In some embodiments, the controller may adjust the impedance between the electrostatic shield and the inductive coupling element in parallel with adjusting the impedance between the electrostatic shield and ground, such that accurate and repeatable control of the RF voltage on the electrostatic shield may be achieved.

According to example aspects of the present disclosure, a plasma processing apparatus may include a process chamber to process a workpiece and a baffle structure (e.g., a separation baffle) to separate (e.g., partially separate, also referred to as a separation baffle) the process chamber from the plasma chamber. For example, a separation baffle may be interposed between a plasma chamber and a workpiece support pedestal in a processing chamber. The separation baffle may block one or more portions of the flow path of the plasma and gas from the plasma generation region to the workpiece to partially absorb or divert charged particles in the gas stream flowing from the plasma chamber down to the workpiece.

In some embodiments, the separating baffle may be devoid of holes such that gas does not flow through the separating baffle, e.g., a disk devoid of holes. In some embodiments, the separating baffle may have a disk shape and a footprint that is symmetric about a central axis of the cylindrical plasma source volume such that a center of the separating baffle is located above a substantial center of the workpiece support. In some embodiments, the separation baffle may have a diameter between about 0.7 and as small as about 0.10 of the diameter of the chamber at that location. For example, the separating baffle may cover only a portion (e.g., less than about 50%, such as less than about 25%) of the flow area from the inductive coupling element to the workpiece. In some embodiments, the separating baffle may be circular and symmetrical with its center located above the center of the workpiece so that the plasma may diffuse or flow around the separating baffle as the gas goes down to the workpiece. The separation baffle may be made of an electrically insulating material or an electrically conductive material. In some embodiments, the separation baffle may be between about 5cm and about 20cm from the workpiece.

In some embodiments, the separation baffle may have a plurality of holes that allow some gas to flow through the separation baffle. For example, the separation baffle may be a small grid with a plurality of small holes. The aperture diameter may be of the same order of magnitude or the same size as the thickness of the separating baffle such that a majority of the ions entering the aperture cannot penetrate the separating baffle. In some embodiments, the separation baffle may be made of an electrically conductive material, such as metal, silicon, carbon, or other material having some measure of electrical conductivity.

In some embodiments, the separation stop may be electrically biased by an external power source. The bias voltage may be controlled by a controller for the processing chamber. The bias voltage may vary from one process to another or from one step to another in a process for a single workpiece or multiple workpieces. In this case, wires or conductive struts or supports may be used to provide current to the separation baffle from an external power source.

In some embodiments, the separating baffle may provide a uniform density distribution of the plasma over the workpiece so that the processing of the workpiece may be uniform. Such a separating baffle may be made of an electrically insulating material or an electrically conducting material. The isolation barrier made of a conductive material may be electrically grounded or electrically floating. In some embodiments, such a separation baffle may not be electrically biased to cause enhanced ion collection, or receive ion bombardment, or cause the potential of the plasma to rise.

In some embodiments, when performing an isotropic etch process, the plasma processing apparatus may include a complete separation baffle (e.g., a grid) such that all gas from the chamber flows through the separation baffle to the workpiece, where the plasma energized by the inductive coupling element flows. The separating baffle may partially or almost completely absorb charged particles from the gas flow flowing from the plasma chamber to the workpiece to reduce charging of the workpiece and potential ion damage to the workpiece. When the process requires charged particles, the RF plasma potential of the inductive coupling element can be increased to the point where the hollow anode discharge is ignited in the aperture of the separating baffle, causing ionization to occur in the aperture of the separating baffle, thereby separately generating a plasma in the gas volume adjacent the separating baffle and adjacent the workpiece.

In some embodiments, the workpiece support pedestal of the processing chamber may be a conductive material and may be electrically grounded such that either or both of the DC and RF impedances of the pedestal ground are less than or about 5 ohms. In some cases, the plasma generated by the inductive coupling element may extend to a volume above a workpiece support pedestal made of a conductive material, typically when a large RF voltage value is present on the electrostatic shield. Thus, within the setting of the adjustable reactive impedance circuit from the electrostatic shield to ground, the plasma processing apparatus may include a space charge sheath between the plasma and the workpiece or workpiece support pedestal, such that ions from the plasma above the pedestal may be accelerated by an electric field in the space charge sheath to bombard the workpiece supported on the pedestal.

In some embodiments, one or more metal or conductive walls of the process chamber may be electrically grounded. In some embodiments, a definition referred to as R may be defined_AIs equal to the ratio of the combination of the surface area of the processing chamber wall between the plasma chamber and the dielectric plasma barrier and the area of the workpiece support pedestal divided by the area of the electrostatic shield, and is equal to the total area of the shield and the top cover when the shield is attached to the top cover of the plasma chamber. When R is_ALess than about 3 and while there is some RF voltage on the shield, this may be beneficial for processes that increase the sheath potential at the workpiece surface and decrease the sheath potential at the inner wall of the dielectric wall or top cap. This may reduce ion sputtering from the dielectric wall of the plasma source and may increase the ion energy bombarding the workpiece. Suitable for such low source wall sputtering conditions may be conditions in which the area of the dielectric wall of the plasma chamber (combined with the area of the top cover if it is connected to the shield) is greater than the grounded wall area (e.g., R) of the source including the workpiece support pedestal_ALess than about 1). For any given RF voltage on the electrostatic shield, increasing the electrostatic shield and/or the cover area relative to the grounded wall area will generally result in an increase in the sheath potential above the workpiece, further increasing the energy of ions incident on the workpiece and reducing the ion energy incident on the inner wall of the plasma source. In some embodiments, the plasma chamber may be a portion of a processing chamber in which the wall adjacent to the inductive coupling element is a dielectric material. For example, in some embodiments, a plasma chamber can include a susceptor having a top lid that is a portion of a dielectric wall, an inductive coupling element adjacent the portion of the top lid, and an electrostatic shield (e.g., Faraday shield) between the inductive coupling element and the dielectric wall, and a workpiece support pedestal having a low RF impedance to ground. The metal walls of the plasma chamber surrounding the workpiece support pedestal may be electrically grounded. In some embodiments, the area of the base in combination with the metal wall surrounding the workpiece support base may be less than or about equal to adjacentArea of Faraday shield of dielectric wall (e.g., R)_ALess than about 3). In this case, the ratio of the ground area to the shield area may be less than about 3, or in some embodiments less than about 1.

In some embodiments, at a fixed value of the RF power, in addition to adjusting the impedance of the first reactive circuit between the electrostatic shield and ground, the controller may adjust a value of a second reactive RF impedance between the electrostatic shield and the inductive coupling element to allow the magnitude of the RF potential on the electrostatic shield to be tuned between less than about 5 volts and about 500 volts such that the RF magnitude of the plasma potential is less than about 2 volts_RMSUp to about 300V_RMSWithin the range of (a).

In some embodiments, the plasma processing apparatus may include a baffle structure having one or more dielectric elements (e.g., one or more dielectric baffles, or barriers, or baffles, or dielectric grids, or dielectric walls) in some regions near the workpiece support pedestal. The one or more dielectric elements may confine the plasma to prevent the plasma from filling a portion of the volume of the processing chamber below the workpiece to and including the vacuum pumping line. In this manner, the area of the grounded chamber wall adjacent to the plasma bonded to the pedestal region may be limited to less than 5 times the bonding area of the electrostatic shield, and in some embodiments comprises the top lid of the plasma chamber, and in some embodiments less than the bonding area of the shield and the top lid.

In some embodiments, the electrostatic shield may be spaced from the dielectric wall of the plasma chamber by a distance of less than about 1 centimeter. In some embodiments, the distance between the electrostatic shield and the dielectric wall may be less than about 5 millimeters (mm). In some embodiments, the gap from the electrostatic shield to the dielectric wall may be less than about 2 mm. A smaller gap generally increases the capacitance between the electrostatic shield and the plasma and increases the RF current flowing from the electrostatic shield to the plasma. For example, for a plasma source having an electrostatic shield diameter greater than about 200mm, the capacitance may be increased to at least about 50 picofarads. Through this capacitance, when the inductive coupling element conducts RF current, RF current can flow from the electrostatic shield, through the dielectric wall, and to the plasma. For RF currents typically greater than amperes, this causes the inductive coupling element to have a substantial RF voltage due to its inductance, which may be about 1 microhenry or more. Generally, the smaller the gap from the electrostatic shield to the dielectric wall, the larger the capacitance, thereby increasing the RF plasma potential.

Another example aspect of the present disclosure is directed to a method for processing a workpiece. The method may include allowing a process gas to enter a depleted plasma chamber; generating a plasma from a process gas in a plasma chamber through an inductive coupling element; adjusting an RF voltage of an electrostatic shield positioned between the inductive coupling element and the plasma chamber by adjusting a first adjustable reactive impedance coupled between the electrostatic shield and a ground reference; and further adjusting the voltage of the electrostatic shield between the inductive coupling element and the plasma chamber by adjusting a second adjustable reactance circuit connected between the electrostatic shield and the inductive coupling element; and performing a step in an etching process on the workpiece.

In some embodiments, the exhaust pump may remove used process gases from the plasma chamber. One or more process gases may be flowed into the plasma chamber through one or more mass flow controllers at one or more flow rates that may be automatically controlled to appropriate values independently during different steps of the etch process. The gas pressure in the plasma chamber may be controlled by an automated controller for the etching process. The gas pressure may be controlled within a range between about 1mTorr (e.g., about 0.13 pascal) and about 10Torr (e.g., about 660 pascal). Examples of the process gas may include oxygen (O)₂) Hydrogen (H)₂) Nitrogen (N)₂) Argon (Ar), helium (He), carbon monoxide (CO), carbon dioxide (CO)₂) Ammonia (NH)₃) Methane (CH)₄) Water vapor (H)₂O), chlorine (Cl)₂) Boron tribromide (BBr)₃) Boron trichloride (BCl)₃) And one or more fluorinated gases including tetrafluoromethane (CF)₄) Nitrogen trifluoride (NF)₃) Sulfur hexafluoride (SF)₆) Hydrogen Fluoride (HF), fluorine gas (F)₂) And other gases.

In some embodiments, the controller may preset the first adjustable reactive impedance from the electrostatic shield to ground such that the magnitude of the adjustable reactive impedance may be at least about 10 ohms and the total impedance from the electrostatic shield to ground may be at least about 5 ohms. The RF power may be turned on to provide RF current to the inductive coupling element (e.g., inductive coil) such that the voltage of the electrostatic shield may be greater than about 10V_RMS. The plasma may then be ignited by the RF electric field adjacent the inner surface of the dielectric wall of the electrostatic shield. The dielectric wall (also referred to as a dielectric window) may form at least a portion of the plasma chamber housing. When the RF power is turned on, the one or more voltage sensors may measure a voltage of the electrostatic shield and may provide the measured voltage of the electrostatic shield to the controller. The controller may tune first and second reactive impedances that make the shield voltage suitable for a first step of the etch process (e.g., plasma ignition).

In some embodiments, the etching process may include an isotropic etching step having an RF plasma potential with an amplitude of less than 3V (e.g., about 2V)_RMS). During this step, the controller may set the first adjustable reactive impedance between the electrostatic shield enclosure and ground to a very low value (e.g., less than about 2 ohms, or less than about 1 ohm), which may be determined by calculating the impedance at L₁And C₁At or near series resonance between the two. The controller may then independently set the second adjustable reactance circuit from the inductive coupling element to the electrostatic shield to approximately C_AParallel resonance, reducing the total reactive impedance from the inductive coupling element to the electrostatic shield to reduce the RF voltage on the electrostatic shield so that the RF voltage can be less than about 10V amplitude (7V)_RMS) Such that the energy of the ion bombardment is sufficiently low (e.g., less than about 2eV) that the scattering of ions in the gas produces a substantially isotropic ion distribution.

In some embodiments, the etching process may includeAn ion assisted etching step with substantial ion bombardment assistance is included. During this step, in some embodiments, the controller may couple the first adjustable reactance circuit L₁And C₁Are arranged in series so as to be connected with C_SThe circuit being in parallel at or near C_SParallel resonance such that the impedance from the electrostatic shield to ground is greater than about 100 ohms. The second adjustable reactance circuit may also be tuned such that the reactance of the second adjustable reactance circuit from the inductive coupling element to the electrostatic shield may be capacitive and less than or about equal to the air gap capacitance (C)_A) A capacitive reactance from the inductive coupling element to the electrostatic shield. Such capacitive reactance of the second adjustable reactance circuit may increase the RF current from the inductive coupling element to the electrostatic shield by at least about 50% to increase the RF voltage of the electrostatic shield to at least about 30V_RMSOr above, and preferably increased to 100V_RMSSuch that the plasma potential may be at least about 10V_RMSAnd preferably greater than about 30V_RMS. This step of the etch process may then be performed until time is exhausted or an endpoint signal from the plasma or diagnostics causes the step to terminate.

In some embodiments, the plasma processing apparatus may perform an etch step, which may be the first step in a multi-step process, where ion bombardment is an important mechanism for activating the etch. In some embodiments, for this etching step, both the first reactive impedance circuit between the electrostatic shield and ground and the second adjustable reactive circuit between the inductive coupling element and the electrostatic shield may be independently tuned by the automated control system according to the method described above, such that the RF potential across the electrostatic shield may be greater than about 50 volts RMS and the RF plasma potential may be greater than about 20 volts RMS. This can then provide workpiece ion bombardment with sufficient energy to activate a Reactive Ion Etch (RIE) reaction on the workpiece surface.

In some embodiments, once the first step of the etching process has been completed, the gas flow and RF power may be changed to the desired settings for the second step of the etching process, which may beAn isotropic etching step for which ion bombardment is greatly reduced. The controller may retune the reactive impedance for a second or subsequent step such that the measured RF voltage of the electrostatic shield is much less than the RF voltage used for the first step. For example, as described above, when the step is an isotropic etching step, the RF voltage of the electrostatic shield may be less than about 10V_RMS。

As another example, the controller may adjust the RF voltage of the electrostatic shield to a value different from the RF voltage of the first step, such as above about 100V_RMS. In this way, a first adjustable reactance circuit from the electrostatic shield to ground and a second adjustable reactance circuit from the inductive coupling element to the electrostatic shield may be provided so that the RF voltage of the electrostatic shield may have a value suitable for the ion bombardment needs. Such values of electrostatic shield voltage as required by the process may come from the second step approach. The controller may compare the measured value to a desired voltage of the electrostatic shield to adjust the first and second adjustable reactance circuits until the measured value equals the desired voltage (e.g., a set value). The use of first and second adjustable reactance circuits can independently achieve a wide range of screening voltages for such processing flexibility. The desired voltage may be pre-programmed, for example in a process "recipe", and/or may be manually input by an operator.

For purposes of illustration and discussion, aspects of the present disclosure are discussed with reference to two steps of an etching process. Using the disclosure provided herein, one of ordinary skill in the art will appreciate that an etch process may include two or more process steps and various control parameters (e.g., values related to reactive impedance, voltage of the electrostatic shield) for each step of the etch process, such that the various control parameters may be adjusted at the beginning of the step and maintained at desired values throughout the process step.

Another example aspect of the present disclosure relates to a plasma processing apparatus. The plasma processing apparatus may include a plasma chamber, a dielectric wall forming at least a portion of the plasma chamberAn inductive coupling element (inductive coupling element) located near the dielectric wall, an electrostatic shield located between the inductive coupling element and the dielectric wall, a first adjustable reactance circuit having at least one variable capacitor connecting the electrostatic shield to ground, a second adjustable reactance circuit having at least one variable capacitor connecting the electrostatic shield to the inductive coupling element. The inductive coupling element can generate a plasma in the plasma chamber when energized with Radio Frequency (RF) energy. The function of the combined first and second adjustable reactance circuits may be to adjust the RF voltage of the electrostatic shield over a wider range. The total impedance from the inductive coupling element to the electrostatic shield and from the electrostatic shield to ground comprises C_AAnd C_SSuch that the parallel combination of the first and second adjustable circuits in parallel and the parasitic capacitance may provide a wide range (e.g., a maximum range) for each total impedance. Such a combination may make these impedances independently tunable so that the shielding RF voltage may be adjusted to an appropriate value.

In some embodiments, the first adjustable reactance circuit connected from the electrostatic shield to electrical ground may be a circuit having a combination of at least one inductor and at least one capacitor, where any component may be adjustable or tunable over a range of reactances. In some embodiments, the first adjustable reactance circuit between the electrostatic shield and ground may include at least an inductor L₁The inductor having a specific capacitance (C)_S) Greater reactance magnitude of (c). Inductor L₁May be fixed or tunable over some portion of the range. Namely: omega L₁>(1/(ωC_S) Where ω is the angular frequency of the main RF power fourier component supplied to the inductive coupling element. Furthermore, the capacitor of the circuit may be fixed or variable, but preferably may vary within a capacitance range from a first lower-limit capacitance value to a second upper-limit capacitance value. For example, the lower limit capacitance value may have an inductor L₁Reactance magnitude of (d): [1/(ω C)_1,min))]>(ωL₁). The upper-limit capacitance may have an amplitude [1/(ω C)_1,max))]When the slave inductor L₁When subtracted from the inductive reactance of (a), produce a combination L₁And C₁Is inductive and is greater than or equal to the magnitude of the reactance of the free space or air gap capacitance, [1/(ω C)_S)]. The first tunable reactance circuit may then be tuned by an automatic control system that tunes capacitor C₁Or inductor L₁Or both, so that the inductor L₁And a capacitor C₁An approximate series resonance may be made, in which case the impedance between the electrostatic shield and ground may be less than about 10 ohms. Moreover, the capacitor C can be tuned₁So that a parasitic capacitance C_SAnd the first reactive circuit are at or near parallel resonance, resulting in a large total impedance (e.g., greater than about 100 ohms) between the electrostatic shield and ground. In the latter case, the net RF current to ground may be reduced, resulting in a higher voltage of the electrostatic shield relative to that without the first adjustable reactance circuit. In some embodiments, the first adjustable reactance circuit connecting the electrostatic shield to ground may be connected to one or more locations on the electrostatic shield closest to the center of the inductive coupling element, or may be connected to any point on the electrostatic shield. In some embodiments, a first tunable circuit may be coupled to one end of the electrostatic shield for calculating the resonance condition inductance L₁May include an inductance from the center of the electrostatic shield to the point where it is connected to the first tunable circuit.

In some embodiments, the second adjustable reactance circuit connected from the inductive coupling element to the electrostatic shield may be a circuit having a combination of at least one inductor and at least one capacitor, where any component may be adjustable or tunable within the reactance range. In some embodiments, the second adjustable circuit may comprise at least an inductor L₂And a capacitor C₂In a series combination. Inductor L₂Can have a specific air-gap (free-space) capacitance (C)_A) Greater reactance magnitude of (c). Inductor L₂May be fixed or tunable over some portion of the range. Namely: omega L>(1/(ωC_A) Where ω is to provide a senseThe angular frequency of the fourier component of the dominant RF power of the element should be coupled. In addition, a capacitor C connecting the inductive coupling element and the electrostatic shield₂And may be fixed or variable. Capacitor C₂May have a secondary as C₂A first capacitance of lower limit to as C₂The upper limit of (2) is the capacitance range of the second capacitance. A first capacitor C_2,minShould have a size greater than inductor L₂Reactance magnitude of (d): [1/(ω C)_2,min))]>(ωL₂)。C₂May have a reactance of such a magnitude that [1/(ω C) is present_2,max))]So that when the slave inductor L₂Minus the reactance (i.e., ω L) of the inductor₂) When it leads to a series combination L₂And C₂Is a net inductance and is greater than the magnitude of the reactance of the free space or air gap capacitance, [1/(ω C)_A)]. The second tunable reactance circuit may then be tuned by an automatic control system that tunes capacitor C₂Or inductor L₂Or both, so that the inductor L₂And a capacitor C₂Series resonance may occur, in which case the impedance between the inductive coupling element and the electrostatic shield is less than about 10 ohms. In addition, the capacitor C can be tuned₂Such that an air gap capacitance C_AAnd the second reactive circuit, resulting in a large total impedance (e.g., greater than about 100 ohms) between the electrostatic shield and the inductive coupling element. In the latter case, there may be a reduced net RF current between the inductive coupling element and the electrostatic shield relative to the case without the second adjustable circuit, which results in a smaller inductive RF potential on the electrostatic shield induced by capacitive coupling from the inductive coupling element. In some embodiments, the second adjustable reactance circuit may connect one or more locations on the inductive coupling element near the center of the inductive coupling element to the electrostatic shield, or may connect any point on the inductive coupling element to the electrostatic shield. In some embodiments, the second tunable circuit may connect one end of the inductive coupling element to the electrostatic shield. For calculating the resonance condition, the inductance L₂May include coupling from inductionInductance of the center of the element to its connection point.

In one of the above cases, a second reactive circuit connecting the electrostatic shield to the inductive coupling element may be tuned to a low impedance near or at series resonance to provide an increased RF voltage across the electrostatic shield. In some embodiments, a first adjustable reactance circuit connecting the electrostatic shield and ground may further increase the RF voltage across the electrostatic shield by tuning a variable capacitor in the first adjustable reactance circuit such that the first reactance circuit has the total reactance of the inductance such that it combines in parallel with the parasitic capacitance, thereby increasing the total impedance from the electrostatic shield to ground. In this case, for a given level of RF power input to the inductive coupling element, the RF voltage on the electrostatic shield can be increased (e.g., maximized) and the energy of ion bombardment onto the workpiece or substrate can be increased (e.g., maximized).

For the case where a very low shielding voltage is required, the second adjustable circuit may be tuned for the second reactive circuit and the air-gap capacitance C_AAnd at the same time by tuning the reactance of the first adjustable circuit to the capacitor C₁And an inductor L₁Further reducing the RF voltage across the electrostatic shield. This may reduce (e.g., minimize) the value of the RF voltage on the electrostatic shield to near or less than 1V_RMSSuch that the value of the RF plasma potential can give a very low (e.g., less than about 2eV) energy of ion bombardment of the workpiece from the plasma, which will avoid anisotropic etching.

In some embodiments, the "air gap" capacitance (C) of the inductive coupling element to the electrostatic shield_A) May be between about 5 picofarads and about 500 picofarads, and in some embodiments, the capacitance C_AMay be between about 10 picofarads and about 200 picofarads, the "air gap" capacitance (C)_A) Is the free space capacitance between the two when there is no circuit connection. In some embodiments, the plasma processing apparatus may further include a voltage sensor configured to measure a voltage of the electrostatic shield. In some embodiments, the static electricity may be tunedThe shield is connected to a second adjustable reactance circuit of the inductive coupling element to change the total impedance between the inductive coupling element and the electrostatic shield from series resonance of a circuit having a very small impedance value (e.g., less than about 1 ohm) to a second circuit with an air gap capacitance C_AThereby giving a very large impedance value (e.g., greater than about 100 ohms). The plasma processing apparatus may further include a controller that adjusts a first adjustable reactance impedance circuit (e.g., a variable capacitor C) between the electrostatic shield and ground by adjusting a first adjustable reactance impedance circuit based on a measured voltage of the electrostatic shield₁) To automatically or manually adjust the voltage of the electrostatic shield. In some embodiments, the controller may adjust a second adjustable reactance circuit (e.g., a variable capacitor C) connecting the electrostatic shield with the inductive coupling element₂) To further adjust (increase the previous maximum RF voltage or decrease the previous minimum RF voltage) the voltage of the electrostatic shield.

For purposes of illustration and discussion, aspects of the present disclosure are discussed with reference to a "workpiece," substrate, "or" wafer. Those skilled in the art, having the benefit of the disclosure provided herein, will appreciate that example aspects of the present disclosure may be used in association with any semiconductor wafer or substrate or other suitable substrate or workpiece. A "pedestal" is any structure that can be used to support a workpiece. Further, the term "about" or "approximately" used in connection with a numerical value means within 10% of the stated numerical value.

As used herein, a parallel resonance condition with parasitic capacitance occurs between the electrostatic shield and the ground reference when the net inductive reactance of the adjustable reactive impedance circuit is approximately equal to the magnitude of the reactance of the parasitic capacitance at the frequency of the RF energy applied to the inductive coupling element. In some embodiments, a parallel resonance condition may occur and/or a parallel resonance condition may be detected when the voltage on the electrostatic shield is within 10% of a relative maximum. A parallel resonance condition with parasitic capacitance occurs between the electrostatic shield and the inductive coupling element reference when the net inductive reactance of the adjustable reactive impedance circuit is approximately equal to the magnitude of the reactance of the parasitic capacitance at the frequency of the RF energy applied to the inductive coupling element. In some embodiments, a parallel resonance condition may occur and/or a parallel resonance condition may be detected when the voltage on the electrostatic shield is within 10% of a relative minimum value. A series resonance condition of the adjustable reactive impedance circuit occurs when the net reactance of the inductor of the adjustable reactive impedance circuit is approximately equal to the reactance of the capacitor of the adjustable reactive impedance circuit at the frequency of the RF energy applied to the inductive coupling element. In some embodiments, a parallel resonance condition may occur and/or a parallel resonance condition may be detected when the voltage on the electrostatic shield is within 10% of a relative minimum value.

An example embodiment of the present disclosure relates to a plasma processing apparatus. The plasma processing apparatus may include a plasma chamber configured to be capable of holding a plasma. The plasma processing apparatus may include a dielectric window forming at least a portion of a wall of the plasma chamber. The plasma processing apparatus may include a gas source configured to supply a process gas to the plasma chamber. The plasma processing apparatus can include an inductive coupling element positioned proximate the dielectric window. The inductive coupling element can be configured to generate a plasma from the process gas in the plasma chamber when energized with Radio Frequency (RF) energy. The plasma processing apparatus may include a process chamber having a workpiece support configured to support a workpiece. The processing chamber may be in fluid communication with the plasma chamber. The plasma processing apparatus can include an electrostatic shield positioned between the inductive coupling element and the dielectric window. The electrostatic shield may be grounded to a ground reference via an adjustable reactive impedance circuit. The electrostatic shield may have a parasitic capacitance to the ground reference. The adjustable reactive impedance circuit may be configured to adjust a range of reactance between the electrostatic shield and the ground reference between a capacitively-reactive condition and an inductively-reactive condition at a frequency of the RF energy provided to the inductive coupling element. The reactance range may include an inductive reactance sufficient to achieve a parallel resonance condition with a parasitic capacitance between the electrostatic shield and the ground reference.

In some embodiments, the plasma processing apparatus may include a baffle structure. The baffle structure may comprise a plurality of dielectric confinement elements. At least two of the plurality of dielectric confinement elements may be separated by a gap. The gap may be less than about 1cm in width. In some examples, the plurality of dielectric confinement elements may include a plurality of dielectric chamber liners mounted substantially parallel to a grounded sidewall of the process chamber. In some implementations, the baffle structure may be located between the plasma chamber and the processing chamber. The baffle structure may have a diameter in a range of about 10% to about 70% of the diameter of the plasma chamber. The baffle structure may be configured to absorb one or more charged species from the plasma. In some cases, the center of the baffle structure may be located above the approximate center of the workpiece support.

In some embodiments, the adjustable reactive impedance circuit may include an inductor and a variable capacitor connected in series. The variable capacitor has a capacitance range of less than 0.9C_sA lower limit and greater than about C_s/(a-1) upper limit, wherein C_sIs the parasitic capacitance between the electrostatic shield and the ground reference, and a is a constant greater than about 1.01.

In some embodiments, the plasma processing apparatus may include a second adjustable reactive impedance circuit coupled between the electrostatic shield and the inductive coupling element. The second adjustable reactive impedance circuit may be configured to adjust a reactance between the inductive coupling element and the electrostatic shield between a condition of capacitive reactance and a condition of inductive reactance at a frequency of the RF energy provided to the inductive coupling element.

Another example embodiment of the present disclosure is directed to a plasma processing apparatus. The plasma processing apparatus may include a plasma chamber configured to be capable of holding a plasma. The plasma processing apparatus may include a dielectric window forming at least a portion of a wall of the plasma chamber. The plasma processing apparatus may include a gas source configured to supply a process gas to the plasma chamber. The plasma processing apparatus can include an inductive coupling element positioned proximate the dielectric window. The inductive coupling element can be configured to generate a plasma from the process gas in the plasma chamber when energized with Radio Frequency (RF) energy. The plasma processing apparatus may include a process chamber having a workpiece support configured to support a workpiece. The processing chamber may be in fluid communication with the plasma chamber. The plasma processing apparatus can include an electrostatic shield positioned between the inductive coupling element and the dielectric window. The electrostatic shield is associated with a parasitic capacitance between the inductive coupling element and the electrostatic shield. The plasma processing apparatus may include an adjustable reactive impedance circuit coupled between the inductive coupling element and the electrostatic shield. The adjustable reactive impedance circuit may be configured to adjust a reactance between the inductive coupling element and the electrostatic shield between a capacitive reactance condition and an inductive reactance condition at a frequency of the RF energy provided to the inductive coupling element. The adjustable reactive impedance circuit is operable to achieve an inductive reactance that is at least approximately equal to a capacitive reactance of the parasitic capacitance.

In some embodiments, the adjustable reactive impedance circuit may include an inductor and a variable capacitor connected in series. The inductor may have a frequency greater than 1/(ω) for ω energy provided to the inductive coupling element²C_s) An inductance value of, and C_sIs the parasitic capacitance between the electrostatic shield and the ground reference. The variable capacitor may have a range such that the adjustable reactive impedance circuit may achieve a series resonance condition between the inductive coupling element and the electrostatic shield.

In some embodiments, the plasma processing apparatus may include a plurality of dielectric confinement elements. At least two of the plurality of dielectric confinement elements are separated by a gap. The gap has a width of less than about 1 cm. In some cases, the plurality of dielectric confinement elements comprises a plurality of dielectric chamber liners mounted substantially parallel to a grounded sidewall of the process chamber.

In some embodiments, the plasma processing apparatus may include a baffle structure configured to absorb one or more charged species from the plasma. In some implementations, the baffle structure may be located between the plasma chamber and the processing chamber. The baffle structure has a diameter in a range of about 10% to about 70% of the diameter of the plasma chamber. The center of the baffle structure may be located above the approximate center of the workpiece support.

Another example embodiment of the present disclosure is directed to a plasma processing apparatus. The plasma processing apparatus may include a plasma chamber configured to be capable of holding a plasma. The plasma processing apparatus may include a dielectric window forming at least a portion of a wall of the plasma chamber. The plasma processing apparatus may include a gas source configured to supply a process gas to the plasma chamber. The plasma processing apparatus can include an inductive coupling element positioned proximate the dielectric window. The inductive coupling element can be configured to generate a plasma from the process gas in the plasma chamber when energized with Radio Frequency (RF) energy. The plasma processing apparatus may include a process chamber having a workpiece support configured to support a workpiece. The processing chamber may be in fluid communication with the plasma chamber. The plasma processing apparatus can include an electrostatic shield positioned between the inductive coupling element and the dielectric window. The electrostatic shield may be grounded by a first adjustable reactive impedance circuit. The first adjustable reactive impedance circuit may be configured to adjust a reactance between the inductive coupling element and a ground reference in a range from an inductive reactance to a capacitive reactance. The plasma processing apparatus may include a second adjustable reactive impedance circuit coupled between the inductive coupling element and the electrostatic shield. The second adjustable reactive impedance circuit may be configured to adjust a reactance between the inductive coupling element and the electrostatic shield in a range from an inductive reactance to a capacitive reactance.

In some embodiments, the first adjustable reactive impedance circuit is operable to achieve a parallel resonance condition with a parasitic capacitance between the electrostatic shield and a ground reference. For example, in some embodiments, the first adjustable reactive impedance circuit may include an inductor and a variable capacitor coupled in series. The variable capacitor has a range operable to achieve a series resonance condition with an inductor in the first adjustable impedance circuit at a frequency of the RF energy provided to the inductive coupling element.

In some embodiments, the second adjustable reactive impedance circuit is operable to achieve a parallel resonance condition with a parasitic capacitance between the inductive coupling element and the electrostatic shield at a frequency of the RF energy provided to the inductive coupling element. For example, in some embodiments, the second adjustable reactive impedance circuit is operable to achieve a net capacitive reactance between the inductive coupling element and the electrostatic shield of less than about 50 ohms at a frequency of the RF energy provided to the inductive coupling element in the absence of a plasma.

Another example embodiment of the present disclosure is directed to a method for processing a workpiece. The method may include allowing a process gas to enter the plasma chamber. The method can include energizing the inductive coupling element with RF energy to initiate ignition of a plasma induced in the process gas. The method may include adjusting an RF voltage of an electrostatic shield positioned between the inductive coupling element and the plasma chamber. The electrostatic shield may have a parasitic capacitance to a ground reference. The method can include performing an ion assisted etch process on the workpiece based at least in part on the RF voltage of the electrostatic shield. Adjusting the RF voltage of the electrostatic shield may include adjusting a first adjustable reactive impedance circuit coupled between the electrostatic shield and the ground reference to an inductively reactive state such that, in the absence of plasma, a magnitude of a total impedance between the electrostatic shield and the ground reference is at least twice a magnitude of an impedance of a parasitic capacitance between the electrostatic shield and the ground reference at a frequency of the RF energy provided to the inductive coupling element.

In some embodiments, adjusting the RF voltage of the electrostatic shield may include adjusting a first adjustable reactive impedance circuit coupled between the electrostatic shield and the ground reference such that the first adjustable reactive impedance circuit creates a parallel resonance condition with a parasitic capacitance from the electrostatic shield to the ground reference at a frequency of the RF energy provided to the inductive coupling element.

In some embodiments, adjusting the RF voltage of the electrostatic shield may include adjusting a second adjustable reactive impedance circuit coupled between the electrostatic shield and the inductive coupling element to produce a total impedance between the electrostatic shield and the inductive coupling element in the absence of the plasma having a magnitude that is less than half a magnitude of an impedance of a parasitic capacitance between the electrostatic shield and the inductive coupling element.

In some embodiments, the RF voltage of the electrostatic shield may be adjusted to be greater than about 100V_RMS. The first adjustable reactive impedance circuit may include an inductor and a capacitor coupled in series. The second adjustable reactive impedance circuit may include an inductor and a capacitor coupled in series. The parasitic capacitance from the electrostatic shield to the ground reference may be in the range of about 20 picofarads to about 2000 picofarads.

Another example embodiment of the present disclosure is directed to a method for processing a workpiece. The method may include allowing a process gas to enter the plasma chamber. The method can include energizing the inductive coupling element with RF energy to initiate ignition of a plasma induced in the process gas. The method can include adjusting an RF voltage of an electrostatic shield positioned between the inductive coupling element and the plasma, wherein the electrostatic shield has a parasitic capacitance to a ground reference. The method can include performing an isotropic etching process on the workpiece based at least in part on the RF voltage of the electrostatic shield. Adjusting the RF voltage of the electrostatic shield may include adjusting a first adjustable reactive impedance circuit coupled between the electrostatic shield and the ground reference to have a net capacitive reactance such that the first adjustable reactive impedance circuit produces a total impedance between the electrostatic shield and the ground reference in the absence of plasma that is less than half the magnitude of the impedance of the parasitic capacitance between the electrostatic shield and the ground reference at the frequency of the RF energy provided to the inductive coupling element.

In some embodiments, adjusting the RF voltage of the electrostatic shield may include adjusting a first adjustable reactive impedance circuit coupled between the electrostatic shield and the ground reference such that the first adjustable reactive impedance circuit creates a series resonance condition with a parasitic capacitance from the electrostatic shield to the ground reference at a frequency of the RF energy provided to the inductive coupling element.

In some embodiments, adjusting the RF voltage of the electrostatic shield may include adjusting a second adjustable reactive impedance circuit coupled between the electrostatic shield and the electrostatic shield to produce a total impedance between the electrostatic shield and the inductive coupling element in the absence of the plasma having a magnitude greater than twice a magnitude of an impedance of a parasitic capacitance between the electrostatic shield and the ground reference.

In some embodiments, adjusting the RF voltage of the electrostatic shield may include adjusting a second adjustable reactive impedance circuit coupled between the electrostatic shield and the ground-referenced inductive coupling element to produce a net inductive reactance of the second adjustable circuit having a series-parallel resonance condition with a parasitic capacitance between the shield and the inductive coupling element at the frequency of the RF energy provided to the inductive coupling element.

In some embodiments, the RF voltage of the electrostatic shield is adjusted to less than or equal to about 10V_RMS. The impedance of the first adjustable reactive impedance circuit may be set to less than or equal to about 5 ohms at the frequency of the RF energy provided to the inductive coupling element. The parasitic capacitance from the inductive coupling element to the electrostatic shield may be in a range of about 5 picofarads to about 1000 picofarads.

Another example embodiment of the present disclosure is directed to a method for processing a workpiece. The method may include allowing a process gas to enter the plasma chamber. The method can include energizing the inductive coupling element with RF energy to initiate ignition of a plasma induced in the process gas. The method may include adjusting an RF voltage of an electrostatic shield disposed between an inductive coupling element and a plasma chamber to obtain a first RF voltage of the electrostatic shield, the electrostatic shield associated with a parasitic capacitance of a ground reference. The method can include performing an ion assisted etch process on the workpiece based at least in part on the first RF voltage of the electrostatic shield. The method may include adjusting an RF voltage of the electrostatic shield to obtain a second RF voltage of the electrostatic shield. The method can include performing an isotropic etching process on the workpiece based at least in part on the second RF voltage of the electrostatic shield. Adjusting the RF voltage of the electrostatic shield to obtain the first RF voltage of the electrostatic shield may include adjusting a first adjustable reactive impedance circuit coupled between the electrostatic shield and a ground reference such that a total impedance between the electrostatic shield and the ground reference in the absence of a plasma is a first magnitude. Adjusting the RF voltage of the electrostatic shield to obtain the second RF voltage of the electrostatic shield may include adjusting the first adjustable reactive impedance circuit coupled between the electrostatic shield and a ground reference such that a total impedance between the electrostatic shield and the ground reference in the absence of a plasma is a second magnitude. The second amplitude may be less than the first amplitude.

In some embodiments, adjusting the RF voltage of the electrostatic shield to obtain the first RF voltage of the electrostatic shield may include adjusting a second adjustable reactive impedance circuit coupled between the electrostatic shield and the inductive coupling element such that a total impedance without the presence of a plasma between the electrostatic shield and the inductive coupling element is a third magnitude; and adjusting the RF voltage of the electrostatic shield to obtain the second RF voltage of the electrostatic shield may include adjusting a second adjustable reactive impedance circuit coupled between the electrostatic shield and the inductive coupling element such that a total impedance between the electrostatic shield and the inductive coupling element in the absence of the plasma is a fourth magnitude. The third amplitude may be less than the fourth amplitude.

In some embodiments, the first RF voltage of the electrostatic shield is greater than about 100V_RMSAnd the second RF voltage is less than about 10V_RMS. The ion-assisted etch process is performed at a setting of the first adjustable reactive impedance circuit such that a total impedance from the electrostatic shield to the ground reference is greater than about 100 ohms at a frequency of the RF energy provided to the inductive coupling element in the absence of the plasma, and the isotropic etch process is performed at a second impedance of the first adjustable reactive impedance circuit, wherein the second impedance is less than about 10 ohms at the frequency of the RF energy provided to the inductive coupling element.

In some embodiments, the first adjustable reactive impedance circuit includes a first inductor and a first capacitor coupled in series; the second adjustable reactive impedance circuit includes a second inductor and a second capacitor coupled in series. At least one of the first inductor and the first capacitor is tunable, and at least one of the second inductor and the second capacitor is tunable.

Fig. 1 depicts an example plasma processing apparatus according to an example embodiment of the present disclosure. As shown, the plasma processing apparatus 100 includes a process chamber 110 and a plasma chamber 120, the plasma chamber 120 being different from the process chamber 110 but having a volume connected to the volume of the process chamber such that the process chamber is in fluid communication with the plasma chamber. The processing chamber 110 includes a workpiece support or pedestal 112 configured to support or hold a workpiece 114 to be processed, such as a semiconductor wafer. The workpiece support or pedestal 112 may be grounded. In this example illustration, a plasma is generated in the plasma chamber 120 (i.e., the plasma generation region) by the inductively coupled plasma source 135, and desired species are directed from the plasma chamber 120 to the surface of the workpiece 114 through and around the baffle structure (e.g., the separation baffle 200). The baffle structure (e.g., separation baffle) may be configured to absorb charged species from the plasma.

The plasma chamber 120 includes dielectric sidewalls 122 (also referred to as a dielectric window) and a ceiling 124 (also referred to as a conductive ceiling). The dielectric sidewalls 122, top plate 124, and separating baffle 200 define a plasma chamber interior 125. The dielectric sidewalls 122 may be formed of a dielectric material, such as quartz and/or alumina. The inductively coupled plasma source 135 may include an induction coil 130 disposed adjacent the dielectric sidewall 122 around the plasma chamber 120. The inductive coil 130 is coupled to the RF power output of an RF generator 134 through a suitable matching network 132. Process gas may be supplied to the chamber interior from a gas supply 150 and an annular gas distribution channel 151 or other suitable gas introduction mechanism. Examples of process gases may include one or more of the following: oxygen (O)₂) Hydrogen (H)₂) Nitrogen (N)₂) Argon (Ar), helium (He), carbon monoxide (CO), carbon dioxide (CO)₂) Ammonia (NH)₃) Methane (CH)₄)、H₂O, chlorine (Cl)₂)、Boron tribromide (BBr)₃) Boron trichloride (BCl)₃) And one or more fluorinated gases including tetrafluoromethane (CF)₄) Nitrogen trifluoride (NF)₃) Sulfur hexafluoride (SF)₆) Hydrogen Fluoride (HF), fluorine gas (F)₂). When the inductive coil 130 (inductive coupling element) is energized by RF power from the RF power generator 134, a plasma may be generated in the plasma chamber 120. In certain embodiments, the plasma processing apparatus 100 can include an electrostatic shield 128 (e.g., a Faraday shield, or a shield with a conductive material) to reduce capacitive coupling of the inductive coil 130 to the plasma. The metal walls of the process chamber 110 and pedestal 112 are grounded.

According to an example aspect of the present disclosure, as shown in fig. 1, an electrostatic shield 128 is positioned between the inductive coil 130 and the dielectric sidewall 122. The electrostatic shield 128 is grounded via the first adjustable reactance circuit 145 (e.g., via the grounded enclosure 170). The first adjustable reactance circuit 145 may include a variable impedance that in some embodiments is substantially a reactive impedance. The variable impedance may be provided by a series LC circuit with a variable capacitor and/or a variable inductor to allow the impedance of the first adjustable reactance circuit 145 to be varied over a wide range. Each of the first and/or second tunable circuits may also include a modest (<10 ohm) resistance (not shown in fig. 1) along with the inductor and capacitor that helps to widen the capacitance range of the parallel resonance and make tuning of the circuit more stable. In some embodiments, the electrostatic shield 128 is also connected to the ceiling 124 of the plasma chamber 120 such that the ceiling 124 can conduct RF current to/from the plasma generated by the inductive coil 130, either directly or through a thin dielectric liner (not shown in fig. 1), to/from the electrostatic shield 128 and then through the first tunable reactance circuit 145 to ground.

According to an example aspect of the present disclosure, as shown in fig. 1, the electrostatic shield 128 is also connected to the inductive coil 130 through a second adjustable reactance circuit 160. The second adjustable reactance circuit 160 may include a variable impedance that is primarily reactive. The variable impedance may be provided by a series LC circuit with a variable capacitor and/or a variable inductor to allow the impedance of the second adjustable reactance circuit 160 to be varied over a wide range. In some embodiments, the dominant reactive impedance may include a small resistor (approximately <10 ohms) that has a much smaller impedance than an inductor or capacitor, but sufficient to widen the capacitive range of resonance, making the resonance condition more stable.

As shown in fig. 1, the plasma processing apparatus 100 further includes a controller 140 and a voltage sensor 142. The controller 140 controls the RF power generator 134, the first adjustable reactance circuit 145, and the second adjustable reactance circuit 160 to adjust the plasma potential based on the voltage of the electrostatic shield 128. The voltage sensor 142, in some embodiments where it is proximate to the inductive coil 130, measures the voltage of the electrostatic shield 128 and provides a signal, which may be analog or digital, to the controller 140 that is representative of the measured voltage of the electrostatic shield 128. In some embodiments, the controller 140 may control the RF power generator 134, the first adjustable reactance circuit 145, and the second adjustable reactance circuit 160 based on a "recipe" of process conditions that includes a voltage range of the signal received from the voltage sensor 142.

As shown in fig. 1, the controller 140 controls the RF power generator 134 to supply RF power to the plasma through the RF current to the induction coil 130. In some embodiments, to ignite the plasma, the controller 140 may control the voltage of the electrostatic shield 128 to be greater than about 10V_RMSAnd up to about 100V_RMS. The plasma may be ignited by an electrostatic RF field (not shown in figure 1) disposed on the inner surface of the dielectric sidewall 122 adjacent the electrostatic shield 128. The voltage sensor 142 may measure a voltage at a specified point on the electrostatic shield 128 and may provide the measured voltage of the electrostatic shield 128 to the controller 140. The controller 140 may adjust the voltage of the electrostatic shield 128 within a desired range by adjusting the variable impedance of the first adjustable reactance circuit 145 and/or the second adjustable reactance circuit 160 based on the measured voltage of the electrostatic shield provided by the voltage sensor 142 to provide closed loop control.

In some embodiments, the controller 140 may adjust the impedance of the first adjustable reactance circuit 145 from about 10 ohms to 100 ohms by adjusting the impedance of the first adjustable reactance circuit 145 at the primary frequency of the RF current provided by the induction coil 130M and further adjusting the second adjustable reactance circuit 160 to be less than about 1V_RMSTo about 200V_RMSThe voltage of the electrostatic shield 128 is adjusted within the range therebetween. In some embodiments, the controller 140 may adjust the reactive impedance of the first and second reactive impedance circuits to adjust the RF voltage on the electrostatic shield for a particular process step to provide a desired level of ion bombardment for that process step.

For example, in some embodiments, to increase the voltage of the electrostatic shield 128 (e.g., for an ion assisted etch process), the controller 140 may adjust the first adjustable reactance circuit 145 to adjust the first adjustable reactance impedance circuit 145 and the parasitic capacitance (C) from the electrostatic shield 128 to the ground reference_S) Creating a substantially parallel resonance therebetween. The controller 140 may further tune the second adjustable reactive circuit 160 to produce a substantially series resonance of an inductor and a capacitor within the second adjustable reactive impedance circuit 160. In some embodiments, the second reactive circuit may be tuned to be capacitive with a reactance of between about 100 ohms and about 25 ohms to increase RF current from the inductive coupling element to the shield. In some embodiments, to reduce the voltage of the electrostatic shield 128 (e.g., an isotropic etch process), the controller 140 may tune the first tunable reactive circuit 145 to create a substantially series resonance of an inductor and a capacitor within the first tunable reactive impedance circuit 145. The controller 140 may adjust the second tunable reactance circuit 160 to provide a parasitic capacitance (C) between the second tunable reactance circuit 160 and the inductive coupling element to the electrostatic field 128_A) Creating a substantially parallel resonance therebetween, thereby providing a minimum RF voltage across the shield.

In some embodiments, the controller 140 may independently control the first adjustable reactance circuit 145 and the second adjustable reactance circuit 160 to increase or decrease the voltage of the electrostatic shield 128. For example, the controller 140 may individually tune the first tunable reactance circuit 145 to increase or decrease the voltage of the electrostatic shield 128 for various applications, such as plasma ignition, ion assisted etch processes, and/or isotropic etch processes. The controller 140 may individually tune the second tunable reactance circuit 160 to increase or decrease the voltage of the electrostatic shield 128 for these applications.

The controller 140 and/or any controller or other control device disclosed herein may include one or more processors and one or more memory devices. The one or more memory devices may store computer-readable instructions that, when executed by the one or more processors, perform operations. These operations may include, for example, tuning a variable impedance coupled between the electrostatic shield 128 and ground, and/or tuning a variable impedance coupled between the electrostatic shield 128 and the inductive coil 130. These operations may include, for example, controlling RF generator 134. The controller 140 may perform other operations associated with the plasma processing apparatus.

According to an example aspect of the present disclosure, as shown in fig. 1, a separation baffle 200 separates the plasma chamber 120 from the process chamber 110. The separating baffle 200 may block one or more portions of the flow path of the plasma and gas from the plasma generation region to the workpiece 114 to partially absorb or divert charged particles in the gas stream flowing from the plasma chamber 120 down to the workpiece 114. The separation baffle 200 may be used to perform ion blocking and to separate charged and neutral species from the plasma-generated mixture in the chamber 120 to produce a filtered mixture. The filtered mixture may be exposed to the workpiece 114 in the process chamber 110. The separating baffle 200 may also help to reshape the distribution of neutral species passing through the workpiece 114 because the flow rate through the separating baffle 200 is substantially lower than through one or more open areas around the separating baffle 200.

In some embodiments, the separation baffle 200 may be devoid of holes such that gas does not flow through the separation baffle 200, e.g., a disk devoid of holes. In some embodiments, the separating baffle 200 can have a disk shape and a coverage area that is symmetric about the central axis of the cylindrical plasma source volume such that the center of the separating baffle 200 is located above the approximate center of the workpiece support. For example, one or more portions of the separation baffle 200 blocking one or more portions of the flow path may be symmetrically arranged about a central axis of the induction coil 130.

In some embodiments, the diameter of the separating baffle 200 at a location in the plasma chamber 120 may be in the range of about 0.1 to about 0.7 of the diameter of the plasma chamber 120 at that location. For example, the separating baffle 200 may cover only a portion (e.g., less than about 50%, such as less than about 10%) of the flow area from the induction coil 130 to the workpiece 114. In some embodiments, the separating baffle 200 may be circular and symmetrical with its center located above the center of the workpiece 114 so that the plasma may diffuse or flow around the separating baffle 200 as the gas goes down to the workpiece 114. The separation baffle 200 may be made of an electrically insulating material or an electrically conductive material. In some embodiments, the separating baffle 200 may be between about 5cm from the workpiece and about 20cm from the workpiece 114.

In some embodiments, the separation baffle 200 may have a plurality of holes that allow some gas to flow through the separation baffle 200. For example, the separation baffle 200 may be a small grid 210 having a plurality of small holes. Grid 210 covers only a portion of the cross-sectional area of volume 125 of plasma chamber 120. Neutral species may pass through the grid 210 while charged particles do not typically pass through. The airflow may substantially surround grid 210, but the smaller charged portions and neutral species move around grid 210 into a region near the axis of symmetry of grid 210. This can therefore help make the processing rate more uniform by reducing the velocity of the center of the generally higher workpiece 114.

In some embodiments, the hole diameter may be of the same order or the same size as the thickness of the separation baffle 200, such that most ions cannot penetrate the separation baffle. In some embodiments, the separation baffle 200 may be made of an electrically conductive material, such as metal, silicon, carbon, or other material having some measure of electrical conductivity.

In some embodiments, the separation stop 200 may be electrically biased by an external power source 215. The bias voltage may be controlled by a controller 140 of the processing chamber 110. The bias voltage may vary for a single workpiece, depending on the process or steps within the process. In this case, wires or conductive posts or supports may be used to provide current to the separation baffle 200 from an external power source 215.

In some embodiments, the separating baffle 200 may provide a uniform density distribution of the plasma over the workpiece 114 so that the processing of the workpiece 114 may be uniform. In some embodiments, the area of the separating baffle 200 may be up to about 50% to as low as about 10% of the cross-sectional area of the flow path from the induction coil 130 to the workpiece 114. The separation baffle 200 may be made of an electrically insulating material or an electrically conductive material. The separation barrier 200 made of a conductive material may be electrically grounded or electrically floating. In some embodiments, the separation baffle 200 cannot be electrically biased such that the separation baffle 200 can cause enhanced ion collection, or can receive ion bombardment, or cause the potential of the plasma to rise.

In some embodiments, the separating baffle 200 may be a complete barrier when performing an isotropic etch process, such that the entire gas flow from the plasma chamber 120 flows through the separating baffle 200 to reach the workpiece 114. The separating baffle 200 may partially or almost completely absorb charged particles from the gas flow from the plasma chamber 120 to the workpiece 114 to reduce charging of the workpiece 114 and potential ion damage to the workpiece 114. When the process requires charged particles, the RF plasma potential of the induction coil 130 can be increased to the point where the hollow anode discharge is ignited in the separating baffle 200 when it is grounded, causing ionization to occur in the holes in the separating baffle 200, thereby separately generating a plasma in the gas volume below the separating baffle 200 but directly above the workpiece 114.

Fig. 2 depicts an example equivalent circuit 202 of the plasma processing apparatus 100 according to an example embodiment of the present disclosure. As shown in fig. 2, a capacitive coupling 204 is located between the plasma and the lid (also referred to as top plate) 124 (not shown in fig. 2). The lid 124 may be a conductive material that provides a ceiling for the plasma volume. The cover 124 may be connected to ground, or may be electrically floating, or may not be connected to the shield. When the lid 124 is coupled to the electrostatic shield 128, as shown in FIG. 2, the capacitors 204 and 206 may operate in parallel to provide RF current from the electrostatic shield 128 to the plasma. In some embodiments, capacitive coupling 204 and capacitive coupling 206 are dependent on plasma conditions. Capacitance between plasma and electrostatic shield 128206 depend on the dielectric wall material and the sheath thickness at the dielectric wall surface. This capacitance causes RF current to flow from the electrostatic shield 128 to the plasma, thereby allowing the plasma to sustain an RF potential. Capacitive coupling 208 (C)_A) Between the electrostatic shield 128 and the inductive coil 130, the inductive coil 130 is also coupled to an RF power supply 212, and the RF power supply 212 may include a suitable matching network 132 and an RF power generator 134. The free space (air gap) capacitance 209 between the electrostatic shield 128 and the electrically grounded enclosure (not shown) is referred to as C_S. The electrostatic shield 128 is connected to ground through a first tunable circuit 145 comprising an inductor 214 and a variable capacitor 216. In some embodiments, this may also include a small resistor (not shown in FIG. 2) to couple the adjustable circuit to the capacitor C_SThe total impedance from the shield to ground is stabilized near the parallel resonance condition. The tunable circuit may effectively couple the parasitic capacitance 209 (C) between the electrostatic shield 128 and ground_S) Operating in parallel, which may be between about 20 picofarads and about 2000 picofarads. The capacitance of the capacitive coupling 208 may be between about 5 picofarads and about 1000 picofarads. Components 218 and 220 are an inductor and a variable capacitor, respectively, included in the second adjustable reactance circuit 160 connecting the inductive coil 130 to the electrostatic shield 128. In this illustrated embodiment, the tuning of the variable capacitor 220 can allow the overall impedance between the electrostatic shield 128 and the inductive coil 130 to be varied over a very wide range, resulting in a greatly improved voltage range for the RF plasma potential and, therefore, a greatly improved energy of the ions bombarding the workpiece.

In some embodiments, the second adjustable reactance circuit 160 may be tuned to have a low total impedance, a moderate capacitive reactance, or tuned to be in conjunction with a parasitic capacitance C_AAnd (4) parallel resonance. At low total impedance, there may be a large amount of RF current from the inductive coil 130 to the electrostatic shield enclosure 128, and particularly if the first adjustable circuit is used in a high impedance state-e.g. with a capacitor C_S209, the amplitude of the RF voltage on the electrostatic shield can 128 may be closer to the amplitude of the RF voltage on the induction coil 130 (e.g., up to five hundred volts or more). If the second circuit is tuned to a moderate capacitive reactance(<100 ohms) the voltage on the shield may also be significant, thereby providing increased RF current from the coil to the shield. By appropriately controlling the circuit with inductor 218 and capacitor 220, the voltage across electrostatic shield 128 may be increased (e.g., maximized). The second adjustable reactance circuit 160 may also be adjusted to have a low (e.g., minimum) impedance that may be achieved if the second adjustable reactance circuit 160 is tuned such that the capacitive reactance causes the inductive reactance of the circuit to be zero.

To increase the maximum possible voltage of the electrostatic shield, the first adjustable reactance circuit 145 may also be tuned by adjusting the capacitor 216 so that the total reactance of the first adjustable reactance circuit 145, including all elements in the circuit, may have the same magnitude (but opposite sign) as the capacitive reactance of the capacitance 209 from the electrostatic shield 128 to ground. In this case, there may be a parasitic capacitance (C) of the first tunable reactance circuit 145 with the air gap and electrostatic shield 128_S) The parallel resonance of the other contributors to ground, and the impedance to ground (in the absence of plasma) of the electrostatic shield 128 can be significantly increased (e.g., maximized). This may provide a low (e.g., minimum) ground current from the electrostatic shield 128, thereby providing a high (e.g., maximum) RF voltage on the electrostatic shield 128. The RF voltage may then cause a high (e.g., maximum) RF current to be capacitively coupled from the electrostatic shield 128 to the plasma, resulting in a high (e.g., highest) sheath voltage from the plasma to the workpiece 114, giving a high (e.g., highest) ion energy to bombard the workpiece 114.

In some embodiments, this may effectively ground the electrostatic shield 128 when the first adjustable reactance circuit 145 is tuned to the series resonance of the capacitor 216 and the inductor 214. Then, if the second tunable reactance circuit 160 is tuned to the air gap capacitance 208 (C) from the inductive coil 130 to the electrostatic shield 128_A) And (4) parallel resonance. There may be a low (e.g., minimal) RF current from the inductive coil 130 to the electrostatic shield 128. As a result, the shield RF voltage may be low (e.g., very close to zero volts).

FIG. 3 depicts a plasma processing apparatus according to an example embodiment of the present disclosureAn exemplary equivalent circuit 250 for the device 100. As shown in fig. 3, the first adjustable reactance circuit 145 includes a series combination of an inductor 214 and a variable capacitor 216. The second adjustable reactance circuit 160 comprises a series combination of an inductor 218 and a variable capacitor 220. The first adjustable reactance circuit 145 is arranged in parallel with a shunt capacitance (Cs)209 to ground. The second adjustable reactance circuit 160 is coupled to a capacitor (C)_A)208 are arranged in parallel. To increase the voltage of the electrostatic shield 128 (not shown in fig. 3), the first adjustable reactance circuit 145 may be adjusted to provide a first adjustable reactance impedance circuit 145 and a parasitic capacitance (C)_S)209, a parallel resonance is generated. The second adjustable reactance circuit 160 may be adjusted to create a series resonance of the inductor 218 and the capacitor 220. Alternatively, the second adjustable reactance circuit may be tuned to have a relatively low capacitive reactance, thereby increasing the RF current from the inductive coupling element to the shield, resulting in a higher RF voltage on the shield. To reduce the voltage of the electrostatic shield 128 (not shown in fig. 3), the first adjustable reactance circuit 145 may be adjusted to create a series resonance of the inductor 214 and the variable capacitor 216. If the second adjustable reactance circuit 160 is then adjusted to provide a difference between the second adjustable reactance impedance circuit 160 and the parasitic capacitance (C)_A)208, a parallel resonance condition or a near parallel resonance condition is created, the shielding voltage may be reduced even more.

Fig. 4 depicts a flowchart of an example method (300) according to an example embodiment of the present disclosure. The method (300) may be implemented using the plasma processing apparatus 100 of fig. 1. Fig. 4 depicts the steps performed in a particular order for illustrating and discussing the chamber configuration of fig. 1. Those skilled in the art who have the benefit of the disclosure provided herein will appreciate that various steps of any of the methods described herein may be omitted, expanded, performed concurrently, rearranged and/or modified in various ways without departing from the scope of the present disclosure. Moreover, various additional steps (not shown) may be performed without departing from the scope of the present disclosure.

At (310), the method may include allowing a process gas to enter the plasma chamber. For example, one or more process gases may be supplied from the gas source 150 and the annular gas distribution passage151 or other suitable gas introduction mechanism is provided to the chamber interior 125. Examples of process gases may include one or more of the following: oxygen (O)₂) Hydrogen (H)₂) Nitrogen (N)₂) Argon (Ar), helium (He), carbon monoxide (CO), carbon dioxide (CO)₂) Ammonia (NH)₃) Methane (CH)₄)、H₂O, chlorine (Cl)₂) Boron tribromide (BBr)₃) Boron trichloride (BCl)₃) And one or more fluorinated gases including tetrafluoromethane (CF)₄) Nitrogen trifluoride (NF)₃) Sulfur hexafluoride (SF)₆) Hydrogen Fluoride (HF), fluorine gas (F)₂)。

At (320), the method may include energizing an inductive coupling element to initiate ignition of a plasma induced in the process gas. For example, prior to generating the plasma, the controller 140 may adjust the voltage of the electrostatic shield to generate a trigger voltage (e.g., greater than or about 10 volts RMS) to ignite the plasma. When the inductive coil 130 is energized by RF power from the RF power generator 134, a plasma may be generated in the process gas in the plasma chamber 120.

At (330), the method may include adjusting a voltage of an electrostatic shield located between the inductive coupling element and the plasma chamber to obtain a first voltage of the electrostatic shield. For example, to increase the voltage of the electrostatic shield 128 (e.g., above about 30V)_RMS) The controller 140 may tune the first tunable reactance circuit 145 to provide a first tunable reactance impedance circuit 145 and a parasitic capacitance (C)_S)209, resulting in a substantially parallel resonant condition, resulting in a very high impedance from the electrostatic shield 128 to the ground reference. For example, a first adjustable reactive impedance circuit 145 and a capacitor C_SThe impedance of the parallel combination of (a) and (b) may be set to be greater than the parasitic capacitance C_S100 is approximately twice the reactive impedance. The controller 140 may further tune the second adjustable reactance circuit 160 to produce a substantially series resonance of an inductor and a capacitor within the second adjustable reactance impedance circuit 160, or to have a condition of low absolute value of capacitive reactance, such as less than about 50 ohms.

In some embodiments, the second adjustable reactive impedance circuit 160 may include a series combination of an inductor 218 and a capacitor 220. Inductor 218 may be an adjustable inductor such that inductor 218 is tuned to the parasitic capacitance (C) between electrostatic shield 128 and inductive coil 130_A)208 (e.g., where C is between 1 and 2 times the reactance magnitude_AIn the range of about 20 picofarads to about 2000 picofarads). In some embodiments, the capacitor 220 may be a variable capacitor such that the capacitor 220 is adjusted within a range between the first reactance magnitude and the second reactance magnitude. When the first reactance magnitude is subtracted from the reactance of inductor 218, the first reactance magnitude may result in a magnitude greater than the parasitic capacitance (C)_A)208, the net reactance of the reactance magnitude. The second reactance value may be greater than the reactance of inductor 218.

At (340), the method may include performing an ion assisted etch process on the workpiece based at least in part on the first voltage of the electrostatic shield. For example, the first voltage may be regulated to at least about 30V_RMSOr above, such that the plasma potential may be at least about 10V_RMS. For example, the first voltage may be greater than about 50 volts RMS, and as a result, in some embodiments, the RF plasma potential may be greater than about 20 volts RMS. This may then provide ion bombardment of the workpiece 114 with sufficient energy to activate a Reactive Ion Etching (RIE) reaction on the workpiece surface. The controller 140 may compare the measured value to a desired voltage of the electrostatic shield 128 to adjust the reactive impedance until the measured value equals the desired voltage.

At (350), the method may include adjusting a voltage of the electrostatic shield to obtain a second voltage of the electrostatic shield. For example, to reduce the voltage of the electrostatic shield 128 (e.g., less than about 5 volts), the controller 140 may tune the first adjustable reactive circuit 145 to produce an approximate series resonance of an inductor and a capacitor within the first adjustable reactive impedance circuit 145. For example, the impedance of the first adjustable reactive impedance circuit 145 may be set to less than about 10 ohms. The controller 140 may tune the second adjustable reactance circuit 160 to match the parasitic capacitance (C) from the inductive coupling element to the electrostatic field 128 at the second adjustable reactance impedance circuit 160_A)208 to create an approximately parallel resonance therebetween.

In some embodiments, the first adjustable reactive impedance circuit 145 may include a series combination of an inductor 214 and a capacitor 216. The inductor 214 may be a tunable inductor such that the inductor 214 is tuned to the parasitic capacitance (C) between the electrostatic shield 128 and the ground reference_S)209 (e.g., where C is between 1 and 2 times the reactance magnitude_SIn the range of about 5 picofarads to about 1000 picofarads). In some embodiments, the capacitor 216 may be a variable capacitor such that the capacitor 216 is adjusted within a range between an upper limit first capacitance and a second lower limit higher capacitance. When combined in series with an inductor, the first upper limit capacitance may result in greater than parasitic capacitance (C) when the first reactance magnitude is subtracted from the reactance of the inductor 214_S)209, the net inductive reactance of the reactance magnitude. The second lower limit capacitance may have a reactance absolute value greater than the reactance of the inductor 214, enabling a series resonance condition.

At (360), the method can include subjecting the workpiece to an isotropic etch process based at least in part on the second voltage of the electrostatic shield. For example, the second voltage may be adjusted to a magnitude of less than about 10V (7V)_RMS) The energy of the ion bombardment is made sufficiently low (e.g., below about 4eV) so that the scattering of ions in the gas produces a virtually isotropic ion distribution. The controller 140 may compare the measured value to a desired voltage of the electrostatic shield 128 to adjust the reactive impedance until the measured value equals the desired voltage.

In some embodiments, prior to the processing step, the controller 410 may adjust the reactive impedance to vary the magnitude of the reactance of the first reactive circuit or the second reactive circuit or both over a substantial range such that the voltage of the electrostatic shield 128 may be up to 200V for an appropriate parallel resonant impedance value_RMSOr more. In some embodiments, the controller 410 may adjust the reactive impedance such that the voltage of the electrostatic shield 128 may be less than 5V for an approximate series resonant impedance value of the first adjustable reactive circuit on the order of 10 ohms or less_RMS。

In some embodiments, there may be three or more exemplary modes of operation: first, to strike a plasma or provide plasma bombardment energy (e.g., greater than about 5eV and less than about 50eV) on the workpiece 114, wherein the first adjustable reactance circuit 145 is set by adjusting the first adjustable reactance circuit to achieve a high total impedance from the electrostatic shield 128 to ground by adjusting the first reactance circuit 145 to have a capacitive reactance C from the shield to ground_SNearly equal inductive reactance magnitude to provide a suitable RF shielding voltage (e.g., greater than about 10V)_RMSAnd less than about 100V_RMS). Second, once the plasma is struck and when an isotropic etch mode of operation is desired, in some embodiments, variable capacitor 216 of first tunable reactance circuit 145 may be tuned to obtain a series resonance of the first tunable circuit consisting of inductor 214 and capacitor 216 as shown in fig. 2, such that the impedance of first tunable reactance circuit 145 is very low. This may result in a low RF voltage on the electrostatic shield 128. To achieve even lower voltages (e.g., minimize) on the electrostatic shield 128 when a reduction in plasma potential is desired, the impedance of the second adjustable reactance circuit 160 may be set to be inductive and approximately equal in magnitude to the air gap capacitance C between the inductive coil 130 and the electrostatic shield 128_AThe impedance of (c). This can be done in the second tunable circuit 160 and the air gap capacitance C in fig. 2_A208, a near parallel resonance condition is created which substantially reduces the total RF current from the induction coil 130 to the electrostatic shield 128 and makes the screen voltage even smaller. Finally, to achieve the highest voltage on the electrostatic shield 128 and high (e.g., maximum) ion bombardment energy at the workpiece 114, the impedance of the first adjustable reactance circuit 145 may be made equal in magnitude to the parasitic capacitance C in fig. 2_S209 to adjust the first adjustable reactance circuit 145, which results in an increased value of the screen voltage as measured by the sensor 142 and controlled by the controller 140. The second adjustable reactive impedance 160 may then be adjusted to be net capacitive such that the RF current flowing from the inductive coil 130 to the electrostatic shield 128 is greater than through the capacitance C in fig. 2_A208. Then can adjustTwo tunable capacitive reactances to reduce the capacitive reactance of the tunable circuit (by adding capacitance) to provide up to about 200V_RMSOr the expected value of the shield voltage above.

For purposes of illustration and discussion, aspects of the present disclosure are discussed with reference to two steps of an etching process. Using the disclosure provided herein, one of ordinary skill in the art will appreciate that an etch process may include two or more process steps and various control parameters (e.g., values related to the reactive impedances of the first and second tunable reactance circuits, and/or the voltage of the electrostatic shield) for each step of the etch process such that the various control parameters may be adjusted at the beginning of the step and maintained at desired values throughout the process steps.

Fig. 5 depicts an example plasma processing apparatus 400 according to an example embodiment of the present disclosure. The plasma processing apparatus 400 is similar to the plasma processing apparatus 100 of fig. 1. The plasma processing apparatus 400 includes a plasma chamber interior 125 for forming a plasma and a processing chamber 110 containing a workpiece support pedestal 112. The second adjustable reactance circuit 160 includes an inductor 218 and a variable capacitor 220.

The controller 140 and/or any controller or other control device disclosed herein may include one or more processors and one or more memory devices. The one or more memory devices may store computer-readable instructions that, when executed by the one or more processors, perform operations. These operations may include, for example, tuning a variable impedance coupled between the electrostatic shield 128 and ground, and/or tuning a variable impedance coupled between the electrostatic shield 128 and the inductive coil 130. These operations may include, for example, controlling RF generator 134. The controller 140 may perform other operations associated with the plasma processing apparatus.

According to an example aspect of the present disclosure, as shown in fig. 5, the plasma processing apparatus 400 further includes a plurality of dielectric confinement elements 410 (e.g., dielectric partitions, dielectric baffles, or dielectric chamber liners) positioned in a region around the workpiece support pedestal 112. The spacer is shown in fig. 5, while the gasket (not shown in fig. 5) may be supported closer to and parallel to the grounded wall at a distance of a few millimeters to as much as about 10 millimeters from the grounded wall. These liners can allow gas flow between the liner and the grounded wall, but prevent plasma from entering the area of the grounded wall that they cover. The dielectric elements 410 collectively have a narrow gap (e.g., less than about 1cm) between adjacent dielectric elements, and for the workpiece support and for the baffle or baffle plate shown in fig. 5, for the grounded wall of the processing chamber, the plasma may be confined to prevent it from filling some portion of the remaining volume of the processing chamber 110. These dielectric confinement elements are configured to cover only a portion of the grounded wall area such that they allow plasma access to other portions of the grounded wall area of the processing chamber, rather than the entire grounded wall area. The elements are configured to have a gap of about 1 centimeter or less between them, dividing the volume of the second chamber into a first sub-volume and a second sub-volume fluidly connected by the gap between the dielectric confinement elements. In this manner, the wall area of the processing chamber 110 that is accessible to the plasma to conduct the RF current to ground is limited, and in some embodiments may be limited to having an area comparable to or smaller than the area of the electrostatic shield 128 and ceiling 124. Thus, the area of the grounded wall where the plasma is closest to and able to conduct RF current is reduced compared to fig. 1, which results in an increase in the RF and DC potential of the plasma relative to those of fig. 1.

Fig. 6 depicts an example plasma processing apparatus 500 according to an example embodiment of the present disclosure. The plasma processing apparatus 500 is similar to the plasma processing apparatus 100 of fig. 1 and other plasma processing apparatuses (e.g., fig. 5). For example, the plasma processing apparatus 500 includes a process chamber 110 and a plasma chamber 120 separate from the process chamber 110. The processing chamber 110 includes a substrate support or pedestal 112 operable to hold a workpiece 114, such as a semiconductor wafer, to be processed. In this example illustration, a plasma is generated in the plasma chamber 120 (i.e., the plasma generation region) by the inductively coupled plasma source 135, and the desired species are directed from the plasma chamber 120 to the surface of the workpiece 114 through the barrier assembly 520.

The plasma chamber 120 includes dielectric sidewalls 122 and a ceiling 124. The dielectric sidewalls 122, ceiling 124, and louvers 200 define a plasma chamber interior 125. The dielectric sidewalls 122 may be formed of a dielectric material, such as quartz and/or alumina. The inductively coupled plasma source 135 may include an induction coil 130 disposed adjacent the dielectric sidewall 122 around the plasma chamber 120. The inductive coil 130 is coupled to an RF power generator 134 through a suitable matching network 132. Process gas may be provided to the chamber interior from a gas supply 150 and an annular gas distribution channel 151 or other suitable gas introduction mechanism. Examples of process gases may include one or more of the following: oxygen (O)₂) Hydrogen (H)₂) Nitrogen (N)₂) Argon (Ar), helium (He), carbon monoxide (CO), carbon dioxide (CO)₂) Ammonia (NH)₃) Methane (CH)₄)、H₂O, chlorine (Cl)₂) Boron tribromide (BBr)₃) Boron trichloride (BCl)₃) And one or more fluorinated gases including tetrafluoromethane (CF)₄) Nitrogen trifluoride (NF)₃) Sulfur hexafluoride (SF)₆) Hydrogen Fluoride (HF), fluorine gas (F)₂). When the inductive coil 130 is energized by RF power from the RF power generator 134, a plasma may be generated in the plasma chamber 120. In certain embodiments, the plasma processing apparatus 100 can include a grounded electrostatic shield 128 to reduce capacitive coupling of the inductive coil 130 to the plasma. The walls of the processing chamber 110 and the pedestal 112 are grounded.

The barrier 520 separates the plasma chamber 120 from the process chamber 110. The louvers 520 may be used to perform ion filtering from the mixture generated by the plasma in the plasma chamber 120 to produce a filtered mixture. The filtered mixture may be exposed to the workpiece 114 in the process chamber 110.

In some embodiments, the grill 520 may be a multi-panel grill. For example, the louvers 520 may include first and second louvers spaced in parallel relationship to each other. The first grid plate and the second grid plate can be spaced apart by a distance.

The first grid plate may have a first grid pattern having a plurality of holes. The second grid plate may have a second grid pattern having a plurality of holes. The first gate pattern may be the same as or different from the second gate pattern. The charged particles may recombine on the wall in their path through the apertures of each of the louvers. Neutral species (e.g., radicals) may flow relatively freely through the pores in the first and second grids. The size of the apertures and the thickness of each grid plate can affect the permeability of the charged and neutral particles.

In some embodiments, the first louver may be made of metal (e.g., aluminum) or other conductive material, and/or the second louver may be made of conductive material or dielectric material (e.g., quartz, ceramic, etc.). In some embodiments, the first louver and/or the second louver may be made of other materials, such as silicon or silicon carbide. In the case where the louvers are made of metal or other conductive material, the louvers may be grounded.

In some embodiments, the louvre assembly 520 may be replaced with louvres 210, as discussed above in fig. 1 and 5. The controller 140 may control the bias voltage of the louvers 520 to vary from process to process or from step to step in the processing for a single workpiece 114.

The example plasma processing apparatus 500 of fig. 6 is operable to generate a first plasma 502 (e.g., a remote plasma) in the plasma chamber 120 and a second plasma 504 (e.g., a direct plasma) in the processing chamber 110. As used herein, "remote plasma" refers to a plasma generated remotely from a workpiece (e.g., in a plasma chamber separated from the workpiece by a barrier). As used herein, "direct plasma" refers to a plasma that is directly exposed to a workpiece, such as a plasma generated in a processing chamber having a pedestal operable to support a workpiece.

For example, the plasma processing apparatus 500 of fig. 6 includes a bias source having a bias electrode 510 in the pedestal 112. Bias electrode 510 may be coupled to an RF power generator 514 via a suitable matching network 512. The second, etc. may be produced from the mixture in the process chamber 110 when the bias electrode 510 is energized with RF energyPlasma 504 for direct exposure to workpiece 114. The processing chamber 110 may include an exhaust port 516 for exhausting gases from the processing chamber 110. The workpiece 114 may be processed using the first plasma 502 and/or the second plasma 504. Further, in some embodiments with louvers, supplemental power may be provided to the second plasma 504 by tuning the shield for the first plasma to have approximately 50V_RMSOr above, a substantial screen voltage, a secondary plasma discharge can occur in the apertures of the barrier, contributing to the density and power of the second plasma 504. In embodiments with a barrier but without a second RF power generator, the first plasma in chamber 120 is greater than about 50V at the shield voltage due to the energy input from the charged particles and the secondary plasma in the apertures of the barrier_RMSWill provide a plasma 504. The plasma will have a low spatial potential with minimal RF modulation and be suitable for certain process conditions.

According to an example aspect of the present disclosure, as shown in fig. 6, an electrostatic shield 128 is positioned between the inductive coil 130 and the dielectric sidewall 122. The electrostatic shield 128 is connected to electrical ground via a first adjustable reactance circuit 145. The first adjustable reactance circuit 145 may include a variable impedance reactance element. The variable impedance may be provided by a series LC circuit with a variable capacitor and/or a variable inductor to allow the impedance of the first adjustable reactance circuit 145 to vary over a wide range of values from about 10 ohms or less to at least about 50 ohms, and may exceed about 100 ohms at operating frequencies. In some embodiments, the electrostatic shield 128 may also be connected to the ceiling 124 of the plasma chamber 120 such that the ceiling 124 may conduct RF current to/from the plasma generated by the inductive coil 130, either directly or through a thin dielectric liner (not shown in fig. 6), to the electrostatic shield 128 and then to ground through the first adjustable reactance circuit 145.

According to an example aspect of the present disclosure, as shown in fig. 6, the electrostatic shield 128 is also connected to the inductive coil 130 through a second adjustable reactance circuit 160. The second adjustable reactance circuit 160 may include a variable impedance. The variable impedance may be provided by a series LC circuit with a variable capacitor and/or a variable inductor to allow the impedance of the second adjustable reactance circuit 160 to be varied over a wide range.

As shown in fig. 6, the plasma processing apparatus 500 further includes a controller 140 and a voltage sensor 142. The controller 140 controls the RF power generator 134, the first adjustable reactance circuit 145, and the second adjustable reactance circuit 160 to adjust the plasma potential based on the voltage of the electrostatic shield 128. The voltage sensor 142 measures the voltage of the electrostatic shield 128 in some embodiments where the electrostatic shield 128 is closest to the inductive coil 130 and provides a signal representative of the measured voltage of the electrostatic shield 128 to the controller 140. In some embodiments, the controller 140 may control the RF power generator 134, the first adjustable reactance circuit 145, and the second adjustable reactance circuit 160 based on a "recipe" of process conditions that includes a voltage range of the signal received from the voltage sensor 142.

In some embodiments, the controller 140 may adjust the voltage of the electrostatic shield 128 between or greater than about 10VRMS to about 200VRMS by adjusting the impedance of the first adjustable reactance circuit 145 from about 10 ohms to at least 100 ohms at the primary frequency of the RF current provided by the induction coil 130 and further adjusting the second adjustable reactance circuit 160. In some embodiments, the controller 140 may adjust the reactive impedance of the first and second reactive impedance circuits to adjust the RF voltage on the electrostatic shield for a particular process step to provide a desired level of ion bombardment for that process step.

The controller 140 and/or any controller or other control device disclosed herein may include one or more processors and one or more memory devices. The one or more memory devices may store computer-readable instructions that, when executed by the one or more processors, perform operations. These operations may include, for example, tuning a variable impedance coupled between the electrostatic shield 128 and ground, and/or tuning a variable impedance coupled between the electrostatic shield 128 and the inductive coil 130. These operations may include, for example, controlling RF generator 134. The controller 140 may perform other operations associated with the plasma processing apparatus.

Fig. 7 depicts an example plasma processing apparatus 600 according to an example embodiment of the present disclosure. The upper source of the process chamber 600 is similar to the process chambers of fig. 1, 5, and 6, but the upper chamber includes a lower inductively coupled plasma source in the process chamber in addition to the inductively coupled source of the chamber. This allows the upper plasma source to generate neutral reactive species for the process, while the lower source generates both neutral reactive species and ions that can support processing of the substrate. The two sources can be operated independently so that suitable species, charged and neutral, can be generated.

For example, the plasma processing apparatus 600 includes a process chamber 110 and a plasma chamber 120 separated from the process chamber 110. The processing chamber 110 includes a substrate support or pedestal 112 operable to hold a workpiece 114, such as a semiconductor wafer, to be processed. In this example illustration, a plasma is generated in the plasma chamber 120 (i.e., the plasma generation region) by the upper inductively coupled plasma source 135, and the desired species are directed from the plasma chamber 120 to the surface of the substrate 114 through the barrier assembly 520.

The plasma chamber 120 includes dielectric sidewalls 122 and a top cover or plate 124 having a top plate forming a top defining surface for the plasma. The dielectric sidewalls 122, ceiling 124, and louvers 200 define a plasma chamber interior 125. The dielectric sidewalls 122 may be formed of a dielectric material, such as quartz and/or alumina. The inductively coupled plasma source 135 may include an induction coil 130 disposed adjacent the dielectric sidewall 122 around the plasma chamber 120. The inductive coil 130 is coupled to an RF power generator 134 through a suitable matching network 132. Process gas may be provided to the chamber interior from a gas supply 150 and an annular gas distribution channel 151 or other suitable gas introduction mechanism. Examples of process gases may include one or more of the following: oxygen (O)₂) Hydrogen (H)₂) Nitrogen (N)₂) Argon (Ar), helium (He), carbon monoxide (CO), carbon dioxide (CO)₂) Ammonia (NH)₃) Methane (CH)₄)、H₂O, chlorine (Cl)₂) Boron tribromide (BBr)₃)、Boron trichloride (BCl)₃) And one or more fluorinated gases including tetrafluoromethane (CF)₄) Or other fluorocarbons, nitrogen trifluoride (NF)₃) Sulfur hexafluoride (SF)₆) Hydrogen Fluoride (HF), fluorine gas (F)₂). When the inductive coil 130 is energized by RF power from the RF power generator 134, a plasma may be generated in the plasma chamber 120. In certain embodiments, the plasma processing apparatus 100 can include a grounded electrostatic shield 128 to reduce capacitive coupling of the inductive coil 130 to the plasma.

The barrier 520 separates the plasma chamber 120 from the process chamber 110. The louvers 520 may be used to perform ion filtering from the mixture generated by the plasma in the plasma chamber 120 to produce a filtered mixture. The filtered mixture may be exposed to the workpiece 114 in the process chamber 110.

In some embodiments, the grill 520 may be a multi-panel grill. For example, the louvers 520 may include first and second louvers spaced in parallel relationship to each other. The first grid plate and the second grid plate can be spaced apart by a distance.

The first grid plate may have a first grid pattern having a plurality of holes. The second grid plate may have a second grid pattern having a plurality of holes. The first gate pattern may be the same as or different from the second gate pattern. The charged particles may recombine on the wall in their path through the apertures of each of the louvers. Neutral species (e.g., radicals) may flow relatively freely through the pores in the first and second grids. The size of the apertures and the thickness of each grid plate can affect the permeability of the charged and neutral particles.

In some embodiments, the first louver may be made of metal (e.g., aluminum) or other conductive material, and/or the second louver may be made of conductive material or dielectric material (e.g., quartz, ceramic, etc.). In some embodiments, the first louver and/or the second louver may be made of other materials, such as silicon or silicon carbide. In the case where the louvers are made of metal or other conductive material, the louvers may be grounded.

In some embodiments, the louvre assembly 520 may be replaced with louvres 210, as discussed above in fig. 1 and 5. The controller 140 may control the bias voltage of the louvers 520 (connections not shown) to vary from process to process or step to step in the processing for a single workpiece 114.

The exemplary plasma processing apparatus 600 of fig. 7 is operable to generate a first plasma 602 (e.g., a remote plasma) in the plasma chamber 120 and a second plasma 604 (e.g., a direct plasma) adjacent to the substrate in the processing chamber 110. As shown, the plasma processing apparatus 600 can include angled dielectric sidewalls 622, the dielectric sidewalls 622 extending from the vertical sidewalls 122 associated with the remote plasma chamber 120. The angled dielectric sidewall 622 may form a portion of the processing chamber 110.

The second inductive plasma source 635 may have a second inductive coupling element (inductive coupling element) located near the dielectric sidewall 622. The inductive coil 610 of the second inductive plasma source 635 may be coupled to an RF generator 614 via a suitable matching network 612. When energized with RF energy, the inductive coil 610 may induce a direct plasma 604 adjacent the substrate from the mixture in the process chamber 110. An electrostatic shield 628 (e.g., Faraday shield, or shield with conductive material) may be disposed between the induction coil 610 and the sidewall 622.

The base 112 is movable in the vertical direction V. For example, the base 112 may include a vertical lift 616, and the vertical lift 616 may be configured to adjust a distance between the base 112 and the louvered assembly 200. As one example, the pedestal 112 may be in a first vertical position for processing using the remote plasma 602. The pedestal 112 may be in a second vertical position for processing using the direct plasma 604. The first vertical position may be closer to the louvre assembly 200 than the second vertical position.

The plasma processing apparatus 600 of fig. 7 includes a bias source having a bias electrode 510 in the susceptor 112. Bias electrode 510 may be coupled to an RF power generator 514 via a suitable matching network 512. The processing chamber 110 may include an exhaust port 516 for exhausting gases from the processing chamber 110. The first plasma 602 and/or the second plasma 604 may be used to generate hydrogen radicals. The process chamber 110 and the pedestal 112 are grounded.

According to an example aspect of the present disclosure, as shown in fig. 7, an electrostatic shield 128 is positioned between the inductive coil 130 and the dielectric sidewall 122. The electrostatic shield 128 is connected to ground through a first adjustable reactance circuit 145. The first adjustable reactance circuit 145 may include a variable impedance. The variable impedance may be provided by a series LC circuit with a variable capacitor and/or a variable inductor to allow the impedance of the first adjustable reactance circuit 145 to vary over a wide range of values from about 10 ohms to at least about 100 ohms. The electrostatic shield 128 may also be connected to the ceiling 124 of the plasma chamber 120 such that the ceiling 124 may conduct RF current to/from the plasma generated by the inductive coil 130, either directly or through a thin dielectric liner (not shown in fig. 7), to/from the electrostatic shield 128 and then through the first adjustable reactance circuit 145 to ground.

According to an example aspect of the present disclosure, as shown in fig. 7, the electrostatic shield 128 is also connected to the inductive coil 130 through a second adjustable reactance circuit 160. The second adjustable reactance circuit 160 may include a variable impedance. The variable impedance may be provided by a series LC circuit with a variable capacitor and/or a variable inductor to allow the impedance of the second adjustable reactance circuit 160 to be varied over a wide range.

As shown in fig. 7, the plasma processing apparatus 500 further includes a controller 140 and a voltage sensor 142. The controller 140 controls the RF power generator 134, the first adjustable reactance circuit 145, and the second adjustable reactance circuit 160 to adjust the plasma potential based on the voltage of the electrostatic shield 128. The voltage sensor 142 measures the voltage of the electrostatic shield 128 in some embodiments where the electrostatic shield 128 is closest to the inductive coil 130 and provides a signal representative of the measured voltage of the electrostatic shield 128 to the controller 140. In some embodiments, the controller 140 may control the RF power generator 134, the first adjustable reactance circuit 145, and the second adjustable reactance circuit 160 based on a "recipe" of process conditions that includes a voltage range of the signal received from the voltage sensor 142.

In some casesIn an embodiment, the controller 140 may adjust the impedance of the first adjustable reactance circuit 145 from about 10 ohms to 100 ohms or more at the primary frequency of the RF current provided by the induction coil 130 and further adjust the second adjustable reactance circuit 160 to less than about 1V_RMSTo about 200V_RMSThe voltage of the electrostatic shield 128 is adjusted within the range therebetween. In some embodiments, the controller 140 may adjust the reactive impedance of the first and second reactive impedance circuits to adjust the RF voltage on the electrostatic shield for a particular process step to provide a desired level of ion bombardment for that process step.

The controller 140 and/or any controller or other control device disclosed herein may include one or more processors and one or more memory devices. The one or more memory devices may store computer-readable instructions that, when executed by the one or more processors, perform operations. These operations may include, for example, tuning a variable impedance coupled between the electrostatic shield 128 and ground, and/or tuning a variable impedance coupled between the electrostatic shield 128 and the inductive coil 130. These operations may include, for example, controlling RF generator 134. The controller 140 may perform other operations associated with the plasma processing apparatus.

According to an example aspect of the present disclosure, as shown in fig. 7, an electrostatic shield 628 is connected between the induction coil 610 and the dielectric sidewall 622. The electrostatic shield 628 is grounded (e.g., via a grounded enclosure) via a third adjustable reactance circuit 640. The third adjustable reactance circuit 640 may comprise a variable impedance. The variable impedance may be provided by a series LC circuit with a variable capacitor to allow the impedance of the third adjustable reactance circuit 640 to vary over a wide range of values from about 10 ohms to at least about 50 ohms, for example greater than about 100 ohms.

In accordance with an example aspect of the present disclosure, as shown in fig. 7, the electrostatic shield 628 may also be connected to the inductive coil 610 through a fourth adjustable reactance circuit 660. The fourth tunable reactance circuit 660 may include a variable impedance. The variable impedance may be provided by a series LC circuit with a variable capacitor to allow the impedance of the fourth adjustable reactance circuit 660 to be varied over a wide range.

As shown in fig. 7, the plasma processing apparatus 600 further includes a controller 630 and a voltage sensor 632. The controller 630 controls the RF power generator 614, the third adjustable reactance circuit 640, and the fourth adjustable reactance circuit 660 to adjust the plasma potential based on the voltage of the electrostatic shield 628. The voltage sensor 632 measures the voltage of the electrostatic shield 628 in some embodiments in which the electrostatic shield 628 is proximate to the inductive coil 610 and provides a signal indicative of the measured voltage of the electrostatic shield 128 to the controller 630. In some embodiments, the controller 630 may control the RF power generator 614, the third adjustable reactance circuit 640, and the fourth adjustable reactance circuit 660 based on a "scheme" of process conditions that includes a voltage range of a signal received from the voltage sensor 632.

In some embodiments, the controller 630 may regulate the impedance of the third adjustable reactance circuit 640 from about 10 ohms to 100 ohms at the primary frequency of the RF current provided by the induction coil 610 and further regulate the fourth adjustable reactance circuit 660 at less than about 10V_RMSTo about 200V_RMSThe voltage of the electrostatic shield 628 is adjusted within the range therebetween. In some embodiments, the controller 630 may adjust the reactive impedances of the third and fourth reactive impedance circuits to adjust the RF voltage on the electrostatic shield for a particular process step to provide a desired level of ion bombardment for that process step, even in the absence of separate bias power.

In some embodiments, the controller 630 may control the voltage of the electrostatic shield 628 to be greater than about 20V_RMS. Plasma ignition may be assisted by the resulting RF electric field established at the dielectric sidewalls 622 adjacent the electrostatic shield 628. The voltage sensor 632 may measure the voltage of the electrostatic shield 628 and may provide the measured voltage of the electrostatic shield 628 to the controller 630. The controller 630 may adjust the voltage of the electrostatic shield 628 by adjusting the variable impedance of the circuit 640 based on the measured voltage of the electrostatic shield 628 provided by the voltage sensor 632 to provide closed loop control.

In some embodiments, the controller 630 may control the impedance of the variable impedance of the circuit 640 by changing the impedance from less than about 10 ohmsThe inductor reactance is adjusted to a magnitude equal to the reactance of the free space capacitance between the shield 628 and ground to be less than about 10V_RMSTo about 100V_RMSThe voltage of the electrostatic shield 628 is adjusted within the range therebetween. In some embodiments, the total impedance from the shield 628 to ground may be adjustable over a substantial range, which may include values less than about 10 ohms or greater than about 100 ohms at the frequency of the RF current provided by the induction coil 610. The controller 630 may adjust the variable impedances of the circuit 640 and the circuit 612 to values such that the voltage of the electrostatic shield 628 may be within an acceptable range. For example, the controller 630 may compare the measured voltage of the electrostatic shield 628 to a desired voltage of the electrostatic shield 628 to adjust the variable impedance of the circuit 640 until the measured value is within an acceptable range (e.g., equal to the desired voltage).

Controller 630 and/or any controller or other control device disclosed herein may include one or more processors and one or more memory devices. The one or more memory devices may store computer-readable instructions that, when executed by the one or more processors, perform operations. These operations may include, for example, tuning the variable impedance 640 coupled between the electrostatic shield 628 and ground, and/or tuning the variable impedance 660 coupled between the electrostatic shield 628 and the inductive coil 610. These operations may include, for example, controlling the RF generator 614. The controller 630 may perform other operations associated with the plasma processing apparatus.

Fig. 8 depicts a plasma processing apparatus 100 similar to the plasma processing apparatus 100 of fig. 1. Instead of the baffle structure 200 shown in fig. 1, the plasma processing apparatus 100 of fig. 8 includes a plurality of dielectric confinement elements 213. The dielectric confinement elements may be separated by a gap. The gap may be less than about 1cm in width. The dielectric confinement element 213 may be a dielectric chamber liner mounted generally parallel (e.g., within 15 of parallel) to the grounded sidewall of the process chamber 110.

Example impedance matching network capacitor arrangement (C) for providing power to an inductively coupled plasma source with electrostatic shield_TuningAnd C_Load(s)) And impedance (e.g., connected to the electrostatic shield and the induction coil (Z), respectively_Shield-coil) And electrostatic shield and ground reference (Z)_{Shield-ground}) Impedance of first and second adjustable reactance circuits in between) and an example shielding voltage (V)_Shielding) For example, the operating modes are listed in table 1 below:

case No. 1: adjusting the first and second reactive circuits to produce a series resonance of an inductor and a capacitor in the first adjustable reactive impedance circuit and to produce a series resonance in the second adjustable reactive impedance circuit and C_AParallel resonance is generated between the two;

case No. 2: adjusting a first adjustable reactance circuit to a series resonance condition between inductive and capacitive components in the circuit, resulting in a low impedance from the shield to ground, while a second adjustable reactance impedance circuit from the inductive coupling element to the electrostatic shield is adjusted to have a large value (b:)>200 ohms) inductive reactance;

no. 3 case: if the first and second reactive circuits are not present at all, or if the two adjustable circuits are adjusted to have very large inductive reactances, the two parasitic capacitances C_SAnd C_AHas a typical value;

case No. 4: adjusting the first reactive circuit to have a parallel resonant parasitic capacitance (C) from the electrostatic shield to the ground reference_S) And the second adjustable reactance circuit is tuned to a high inductive reactance or is absent;

case No. 5: tuning the first reactance circuit to AND C_SParallel resonant and adjusting the second reactive circuit to produce a net 150pf parallel capacitance from the inductive coil to the electrostatic shield;

no. 6 case: tuning the first reactance circuit to AND C_SParallel resonant and adjusting the second reactance circuit to produce a net 300pf parallel capacitance from the induction coil to the electrostatic shield;

TABLE 1

These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. Further, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims.