阅读说明：本技术 聚焦环、用于固定基底的卡盘组件以及等离子体处理设备 (Focusing ring, chuck assembly for fixing substrate and plasma processing apparatus ) 是由 宋仁哲 友安昌幸 尹洪珉 林智贤 于 2021-02-19 设计创作，主要内容包括：提供了一种聚焦环、用于固定基底的卡盘组件以及等离子体处理设备。所述聚焦环包括：第一导电层,具有第一厚度和第一比电阻；第二导电层,堆叠在第一导电层上,第二导电层具有大于第一厚度的第二厚度和大于第一比电阻的第二比电阻；以及介电层,位于第一导电层的下表面和第二导电层的上表面中的一个上。(A focus ring, a chuck assembly for fixing a substrate, and a plasma processing apparatus are provided. The focus ring includes: a first conductive layer having a first thickness and a first specific resistance; a second conductive layer stacked on the first conductive layer, the second conductive layer having a second thickness greater than the first thickness and a second specific resistance greater than the first specific resistance; and a dielectric layer on one of a lower surface of the first conductive layer and an upper surface of the second conductive layer.)

1. A focus ring, comprising:

a first conductive layer having a first thickness and a first specific resistance;

a second conductive layer stacked on the first conductive layer, the second conductive layer having a second thickness greater than the first thickness and a second specific resistance greater than the first specific resistance; and

and a dielectric layer on one of a lower surface of the first conductive layer and an upper surface of the second conductive layer.

2. The focus ring of claim 1, wherein the second specific resistance is 10 times to 100 times the first specific resistance.

3. The focus ring of claim 2, wherein the first specific resistance is in a range of 10 Ω cm to 100 Ω cm.

4. The focus ring of claim 1, wherein the first conductive layer comprises silicon and the second conductive layer comprises silicon carbide.

5. A chuck assembly for holding a substrate, the chuck assembly comprising:

a chucking dielectric plate comprising a dielectric material for supporting a substrate;

a chuck body including a conductive material, the chuck body supporting a chuck dielectric plate such that at least one high frequency power is applied to the chuck body; and

a focus ring on an outer peripheral portion of the chuck body to surround the substrate, the focus ring comprising:

a first conductive layer having a first specific resistance,

a second conductive layer on the first conductive layer, the second conductive layer having a second specific resistance different from the first specific resistance, and the first conductive layer and the second conductive layer being combined into a composite conductive layer, an

And a ring dielectric layer on one of the lower surface and the upper surface of the composite conductive layer.

6. The chuck assembly of claim 5, wherein the ring dielectric layer has a thickness satisfied by the following equation (1),

wherein, t₃Denotes the thickness of the ring dielectric layer, t_cDenotes the thickness, ε, of the chuck dielectric plate₃Denotes the dielectric constant, ε, of the Ring dielectric layer_cDenotes the dielectric constant, r, of the chuck dielectric plate₃Represents a radius of the ring dielectric layer from a center position of the chuck body, and r_cRepresenting the radius of the chucking dielectric plate from the center position of the chuck body.

7. The chuck assembly according to claim 6, wherein the ring dielectric layer comprises any one of alumina, quartz, yttria and combinations thereof.

8. The chuck assembly of claim 7, wherein the chucking dielectric plate comprises substantially the same material as the ring dielectric layer.

9. The chuck assembly of claim 7, wherein the composite conductive layer comprises:

the first conductive layer having a first thickness, an

The second conducting layer has a second thickness larger than the first thickness, and the second specific resistance is larger than the first specific resistance.

10. The chuck assembly of claim 9, wherein the first thickness is greater than a thickness of the substrate and satisfies equation (2) below,

wherein, t₁Denotes a first thickness, t, of the first conductive layer_wDenotes the thickness of the substrate, p₁Represents a first specific resistance of the first conductive layer, and ρ_wRepresenting the specific resistance of the substrate.

11. The chuck assembly of claim 9, wherein the high frequency power comprises:

a first transmission power signal transmitted through a first transmission line including the chucking dielectric plate and the substrate and having a first intensity satisfied by the following equation (3), an

A second transmission power signal transmitted through a second transmission line including the focus ring and having a second intensity satisfied by the following equation (4),

wherein z is a position in a height direction of the chuck assembly, x is a position in a radial direction of the chuck assembly, t is an arbitrary time after the high-frequency power is applied to the chuck body, ω is an angular velocity of the high-frequency power, S₁And S₂Respectively a first intensity and a second intensity, S₀Is the initial intensity, alpha, of the high frequency power applied to the chuck body₁And alpha₂Is the attenuation coefficient of the first transmission line and the second transmission line, respectively, and beta₁And beta₂Are the phase coefficients of the first transmission line and the second transmission line, respectively, and

wherein the first thickness and the first specific resistance include a minimum thickness and a minimum specific resistance, which are simultaneously obtained by computer simulation from a minimum point at which a difference between the first intensity and the second intensity is minimized.

12. The chuck assembly according to claim 11, wherein the minimum point is detected as a point in a graph of the first conductive layer at which an intensity difference between the first intensity and the second intensity is minimum, the graph indicating a relationship between a specific resistance of the first conductive layer and the intensity difference between the first intensity and the second intensity under a condition that the first thickness of the first conductive layer is set.

13. The chuck assembly according to claim 9, wherein the second thickness of the second conductive layer is satisfied by the following equation (5),

t₂＝T-(t₁+t₃) (5)，

wherein, t₁A first thickness of the first conductive layer is indicated, and T indicates a total thickness of the focus ring.

14. The chuck assembly according to claim 5, wherein the chucking dielectric plate includes at least a fixed electrode, the fixed electrode being superposed with a center of the chuck body.

15. The chuck assembly according to claim 5, wherein the conductive material of the chuck body comprises any one of aluminum, titanium, tungsten, stainless steel, and combinations thereof.

16. A plasma processing apparatus for performing a plasma processing process on a substrate, the plasma processing apparatus comprising:

a processing chamber having a processing space in which a plasma processing process is performed;

a source supplier at an upper portion of the process chamber to supply a source gas for a plasma treatment process;

a chuck assembly at a lower portion of the process chamber to fix the substrate; and

a power supply applying at least one high frequency power to the chuck assembly and generating a plasma in the processing space for a plasma processing process,

wherein the chuck assembly comprises:

a chucking dielectric plate comprising a dielectric material for supporting a substrate,

a chuck body comprising an electrically conductive material, the chuck body supporting a chuck dielectric plate such that at least the high frequency power is applied to the chuck body, and

a focus ring on an outer peripheral portion of the chuck body to surround the substrate, the focus ring comprising: the first conducting layer is provided with a first specific resistance; a second conductive layer on the first conductive layer, the second conductive layer having a second specific resistance different from the first specific resistance, and the first conductive layer and the second conductive layer being combined into a composite conductive layer; and a ring dielectric layer on one of the lower surface and the upper surface of the composite conductive layer.

17. The plasma processing apparatus of claim 16, wherein the ring dielectric layer has a thickness satisfied by the following equation (6),

wherein, t₃Denotes the thickness of the ring dielectric layer, t_cDenotes the thickness, ε, of the chuck dielectric plate₃Denotes the dielectric constant, ε, of the Ring dielectric layer_cDenotes the dielectric constant, r, of the chuck dielectric plate₃Represents a radius of the ring dielectric layer from a center position of the chuck body, and r_cRepresenting the radius of the chucking dielectric plate from the center position of the chuck body.

18. The plasma processing apparatus of claim 17, wherein the composite conductive layer comprises:

the first conductive layer having a first thickness, an

The second conducting layer has a second thickness larger than the first thickness, and the second specific resistance is larger than the first specific resistance.

19. The plasma processing apparatus of claim 18, wherein the first thickness is greater than a thickness of the substrate and satisfies equation (7) below,

wherein, t₁Denotes a first thickness, t, of the first conductive layer_wDenotes the thickness of the substrate, p₁Represents a first specific resistance of the first conductive layer, and ρ_wRepresenting the specific resistance of the substrate.

20. The plasma processing apparatus of claim 18, wherein the high frequency power comprises: a first transmission power signal transmitted along a first transmission line having the chucking dielectric plate and the substrate and having a first intensity satisfied by the following equation (8); and a second transmission power signal transmitted along a second transmission line having a focus loop and having a second intensity satisfied by the following equation (9),

wherein z is a position in a height direction of the chuck assembly, x is a position in a radial direction of the chuck assembly, t is an arbitrary time after the high-frequency power is applied to the chuck body, ω is an angular velocity of the high-frequency power, S₁And S₂Respectively a first intensity and a second intensity, S₀Is the initial intensity, alpha, of the high frequency power applied to the chuck body₁And alpha₂Are respectively the firstAttenuation coefficients of the transmission line and the second transmission line, and beta₁And beta₂Are the phase coefficients of the first transmission line and the second transmission line, respectively, and

wherein the first thickness and the first specific resistance include a minimum thickness and a minimum specific resistance, which are simultaneously obtained by computer simulation from a minimum point at which a difference between the first intensity and the second intensity is minimized.

Technical Field

Example embodiments relate to a focus ring, a chuck assembly for fixing a substrate having the focus ring, and a plasma processing apparatus having the focus ring, and more particularly, to a focus ring around a chuck assembly to which high frequency power for generating plasma is applied, and a chuck assembly having the focus ring and a plasma etching apparatus having the focus ring.

Background

The density uniformity of the plasma can affect the etch quality of the plasma etch process. Therefore, most plasma etching apparatuses are generally provided with a focus ring. The focus ring may be disposed around a chuck to which the substrate is fixed, and the substrate is surrounded by the focus ring. The plasma in the plasma space is focused by the focus ring onto the substrate, thereby increasing the plasma density on the substrate. A chuck for fixing a substrate and a focus ring around the chuck for focusing plasma on the substrate may be combined into a chuck assembly as a lower structure of the plasma processing apparatus.

Disclosure of Invention

According to an example embodiment, there is provided a focus ring including: a first conductive layer having a first thickness and a first specific resistance; a second conductive layer stacked on the first conductive layer, the second conductive layer having a second thickness greater than the first thickness and a second specific resistance greater than the first specific resistance; and a dielectric layer disposed on one of a lower surface of the first conductive layer and an upper surface of the second conductive layer.

According to other example embodiments, there is provided a chuck assembly including: a chucking dielectric plate including a dielectric material, and the substrate may be fixed to the chucking dielectric plate; a chuck body including a conductive material and supporting a chuck dielectric plate such that at least one high frequency power can be applied to the chuck body; and a focus ring disposed on an outer peripheral portion of the chuck body such that the substrate may be surrounded by the focus ring, and the focus ring may include a composite conductive layer in which at least two conductive layers having different specific resistances may be stacked, and a ring dielectric layer disposed on one of a lower surface and an upper surface of the composite conductive layer.

According to still other example embodiments, a plasma processing apparatus for performing a plasma processing process on a substrate is provided. The plasma processing apparatus may include: a process chamber having a process space in which a plasma treatment process may be performed; a source supplier disposed at an upper portion of the process chamber and supplying a source gas for a plasma treatment process; a chuck assembly disposed at a lower portion of the process chamber and fixing the substrate; and a power supply applying at least one high frequency power to the chuck assembly and generating plasma for a plasma processing process in the processing space. Specifically, the chuck assembly may include: a chucking dielectric plate including a dielectric material, and the substrate may be fixed to the chucking dielectric plate; a chuck body including a conductive material and supporting a chuck dielectric plate such that at least the high-frequency power can be applied to the chuck body; and a focus ring disposed on an outer peripheral portion of the chuck body such that the substrate can be surrounded by the focus ring. The focus ring may include: a composite conductive layer in which at least two conductive layers having different specific resistances may be stacked; and a ring dielectric layer disposed on one of the lower surface and the upper surface of the composite conductive layer.

Drawings

Features will become apparent to those of ordinary skill in the art by describing in detail exemplary embodiments with reference to the attached drawings, wherein:

FIG. 1 is a perspective view illustrating a focus ring for a chuck assembly according to an example embodiment;

FIG. 2 is a cross-sectional view illustrating a configuration of a focus ring shown in FIG. 1 with respect to a substrate;

fig. 3 is a view showing a configuration of a modification of the focus ring shown in fig. 2 with respect to a substrate;

FIG. 4 is a block diagram illustrating a chuck assembly including the focus ring shown in FIGS. 1 and 2 according to an example embodiment;

FIG. 5 is a plan view illustrating a chuck dielectric plate and a ring dielectric layer of a focus ring in the chuck assembly shown in FIG. 4;

fig. 6A is a perspective view showing a first transmission line in which the chucking dielectric plates and the substrate are stacked;

fig. 6B is a perspective view showing a second transmission line in which a ring dielectric layer and a composite conductive layer are stacked;

FIG. 7 is a graph showing the relationship between the specific resistance of the first conductive layer of the focus ring and the difference in intensity between the first transmitted power signal and the second transmitted power signal with respect to the first conductive layer of various thicknesses; and is

Fig. 8 is a block diagram illustrating a plasma processing apparatus having the chuck assembly shown in fig. 4 according to an example embodiment.

Detailed Description

Reference will now be made to example embodiments, which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.

Fig. 1 is a perspective view illustrating a focus ring for a chuck assembly according to an example embodiment. Fig. 2 is a sectional view taken along line I-I' of the focus ring shown in fig. 1.

Referring to fig. 1 and 2, a focus ring 90 according to an example embodiment may include a first specific resistance ρ₁And a first thickness t₁Stacked on the first conductive layer 10 and having a specific resistance p greater than the first₁Second specific resistance ρ₂And is greater than the first thickness t₁Second thickness t₂And a dielectric layer 30 disposed on at least one of a lower surface of the first conductive layer 10 and an upper surface of the second conductive layer 20. For example, as shown in fig. 1 and 2, the dielectric layer 30 may be disposed under the first conductive layer 10 in such a configuration that the dielectric layer 30, the first conductive layer 10, and the second conductive layer 20 may be sequentially stacked on each other (e.g., the first conductive layer 10 may be located between the second conductive layer 20 and the dielectric layer 30).

In the present exemplary embodiment, focus ring 90 may be combined for use with chlorine fluoride (Cl)_xF_y) As a chuck assembly for a plasma etching process of a source gas.

In the present exemplary embodiment, high frequency power may be applied to the lower portion of the chuck assembly and may be transmitted through the substrate W and the focus ring 90, thereby generating plasma for a plasma etching process in a plasma space above the substrate W and the focus ring 90. The high-frequency power transmitted through the focus ring 90 may generate plasma over the peripheral portion E of the substrate W and the focus ring 90, and the high-frequency power transmitted through the substrate W may generate plasma over most of the substrate W except for the peripheral portion E. Hereinafter, a portion of the substrate W other than the peripheral portion E may be referred to as a central portion C, for example, the peripheral portion E may represent an edge portion of the substrate.

The first conductive layer 10 may have such a specific resistance and thickness: so that the attenuation of the high frequency power passing through the first conductive layer 10 can be substantially the same as the attenuation of the high frequency power passing through the substrate W. For this reason, the first conductive layer 10 may have a first specific resistance ρ₁And a first thickness t₁. In contrast, the second conductive layer 20 may have such a specific resistance and thickness: so that the high frequency power transmitted through the first conductive layer 10 can be transmitted through the second conductive layer 20 without substantial attenuation. For this reason, the second conductive layer 20 may have the second specific resistance ρ₂And a second thickness t₂。

For example, the second specific resistance ρ₂May be a first specific resistance p₁About 10 times to about 100 times of, a first specific resistance p₁The attenuation of the high frequency power can be made substantially the same as that of the high frequency power transmitted through the substrate W. In the present exemplary embodiment, the first specific resistance ρ₁And may range from about 10 Ω cm to about 100 Ω cm.

The second conductive layer 20 may be stacked on the first conductive layer 10, and the high frequency power may be sequentially transmitted toward the plasma space through the first conductive layer 10 and the second conductive layer 20 of the focus ring 90.

In detail, the second conductive layer 20 may have a specific resistance much greater than that of the first conductive layer 10, so that high frequency power may be transmitted through the second conductive layer 20 without substantial attenuation. Therefore, the central intensity of the high frequency power, which is the intensity of the high frequency power transmitted through the chuck and the substrate W at the central portion C of the substrate W, may be close to the peripheral intensity of the high frequency power, which is the intensity of the high frequency power transmitted through the focus ring 90 around the peripheral portion E of the substrate W. That is, the intensity difference of the high frequency power transmitted through the substrate W and the high frequency power transmitted through the focus ring 90 may be minimized by the first conductive layer 10 and the second conductive layer 20 of the focus ring 90.

Second conductive layer 20 may be directly exposed to plasma during the plasma treatment process, i.e., exposed to plasma in the plasma space above second conductive layer 20 of focus ring 90. Accordingly, second conductive layer 20 may include an etch-resistant material (e.g., an etch-resistant material that protects second conductive layer 20 from plasma above focus ring 90).

First conductive layer 10 may be covered with second conductive layer 20, and thus, first conductive layer 10 may not be directly exposed to plasma in a plasma treatment process. Therefore, no thickness loss occurs in the first conductive layer 10 despite the repeated plasma treatment process. Since the high frequency power is attenuated when being transmitted through the first conductive layer 10 and substantially no attenuation of the high frequency power occurs during transmission through the second conductive layer 20, the overall attenuation of the high frequency power can be controlled only by controlling the configurations of the first conductive layer 10 and the second conductive layer 20. That is, the first conductive layer 10 and the second conductive layer 20 may function as the composite conductive layer 50 for controlling the overall attenuation of the high frequency power transmitted through the focus ring 90.

In the present exemplary embodiment, the first conductive layer 10 may include a first specific resistance ρ having about 100 Ω cm₁Doped silicon (Si). The second conductive layer 20 may include a second specific resistance ρ having a range of about 1,000 Ω cm to about 10,000 Ω cm₂Doped silicon carbide (SiC).

However, the first conductive layer 10 and the second conductive layer 20 may include any other conductive material as long as the high-frequency power can be sufficiently transmitted with highly controlled attenuation. Specifically, the second conductive layer 20 may include various conductive materials as long as the conductive materials have sufficient etching resistance at high temperature and do not generate particles from the conductive materials.

First thickness t of first conductive layer 10₁May be related to the first specific resistance ρ in this manner₁Determining in a correlated manner: the attenuation of the high frequency power transmitted through the first conductive layer 10 may be made substantially the same as the attenuation of the high frequency power transmitted through the substrate W. For example, when the first conductive layer 10 includes the same material as the substrate W, the thickness of the first conductive layer 10 may be substantially the same as the thickness of the substrate W.

The second conductive layer 20 may have a second thickness T corresponding to the remaining portion (e.g., the remaining portion) of the total thickness T of the focus ring 90 except for the first conductive layer 10 and the dielectric layer 30₂. For example, as shown in FIG. 2, the second thickness t of the conductive layer 20₂A first thickness t of the first conductive layer 10₁And a third thickness t of the dielectric layer 30₃The sum of (a) may constitute the total thickness T of the focus ring 90.

The total thickness T of focus ring 90 may vary depending on the requirements of the plasma processing process and the characteristics of the chuck assembly. In the present exemplary embodiment, focus ring 90 may have a total thickness T of about 3mm to about 6 mm. Thus, the second thickness t of the second conductive layer 20₂Can be determined as the difference between the total thickness T of the focus ring 90 and the sum of the thicknesses of the first conductive layer 10 and the dielectric layer 30.

The dielectric layer 30 may reduce a phase difference of the high frequency power when the high frequency power is transmitted through the focus ring 90 and the substrate W. For example, the dielectric layer 30 may include aluminum oxide (Al)₂O₃) Yttrium oxide (Y)₂O₃) At least one of aluminum nitride (AlN), quartz and combinations thereof.

In detail, since the chuck and the substrate W of the chuck assembly may include a resistive material and a dielectric material, and high-frequency power may be transmitted toward the plasma space through the chuck and the substrate W, the chuck and the substrate W may be simplified into an RC circuit when the high-frequency power is applied to a lower portion of the chuck assembly. Therefore, the high frequency power may have a time delay at the substrate W due to the resistance of the resistive material and the capacitance of the dielectric material. Therefore, when high frequency power is transmitted through the substrate W and the focus ring 90, a phase difference may occur between the transmitted power at the substrate W and the transmitted power at the focus ring 90. Hereinafter, the high frequency power applied to the lower portion of the chuck assembly is referred to as an applied power signal, and the high frequency power transmitted through the substrate W or the focus ring 90 is referred to as a transmission power signal.

The phase difference of the transmitted power signals is generally caused by both resistance and capacitance. However, the phase difference of the transmitted power signal is more caused by the capacitance than the resistance. Accordingly, when the capacitance of the focus ring 90 is substantially the same as that of the chuck assembly, the phase difference of the transmission power signal between the upper portion of the substrate and the focus ring 90 can be minimized. That is, when the focus ring 90 has the same capacitance as that of the chuck in the chuck assembly, the phase difference of the transmission power signal at the focus ring 90 may be similar to the phase difference of the transmission power signal at the substrate W, although different from each other.

In the present exemplary embodiment, the third thickness t of the dielectric layer 30 may be adjusted₃Such that the capacitance of the dielectric layer 30 can be substantially the same as the capacitance of the dielectric body of the chuck. Thus, the total thickness T of the focus ring 90 may be the first thickness T₁A second thickness t₂And a third thickness t₃And may range from about 3mm to about 6 mm.

The first conductive layer 10 and the second conductive layer 20 may be combined with each other without any intermediate into the composite conductive layer 50 of the focus ring 90. For example, the first conductive layer 10 and the second conductive layer 20 may be combined or bonded to each other through a diffusion bonding process.

In detail, the first conductive layer 10 and the second conductive layer 20 may be pressed against each other by pressure, and then may be heated to a temperature lower than the melting point of the first conductive layer 10 and the second conductive layer 20. In this case, atoms of the first conductive layer 10 and the second conductive layer 20 may interdiffuse with each other at an interface between the first conductive layer 10 and the second conductive layer 20 (i.e., on a contact surface) to be bonded or combined into a composite conductive layer 50 (e.g., a single composite conductive layer 50).

In a modified example embodiment, the first conductive layer 10 and the second conductive layer 20 may be combined with each other through a room temperature bonding process. In this case, each of the contact surfaces of the first conductive layer 10 and the second conductive layer 20 may be activated by an ion sputtering process or a plasma treatment process and then may be contacted with each other. Then, the activated contact surfaces of the first and second conductive layers 10 and 20 may be combined or bonded to each other by the inherent welding energy of the first and second conductive layers 10 and 20. Thus, the first conductive layer 10 and the second conductive layer 20 can be combined into the composite conductive layer 50 at room temperature.

Since the conductive body and the dielectric body may be combined or bonded to each other through a room temperature bonding process, the dielectric layer 30 and the composite conductive layer 50 may be combined with each other through a room temperature bonding process.

In another modified example embodiment, the first conductive layer 10 and the second conductive layer 20 may be adhered to each other by an adhesive. In the same manner, the composite conductive layer 50 and the dielectric layer 30 may be adhered to each other by an adhesive. In detail, the adhesive may have good heat transfer characteristics, and thus heat may be sufficiently well transferred between the first conductive layer 10, the second conductive layer 20, and the dielectric layer 30 in the focus ring 90 when the plasma treatment process is performed. In this case, the thickness and dielectric constant of the adhesive may be determined in such a manner that: so that the phase loss of the high frequency power can be minimized whenever the high frequency power is transmitted through the adhesive.

Fig. 3 is a view illustrating a modified configuration of the focus ring shown in fig. 2. The focus ring of the variation in fig. 3 may have substantially the same configuration as the focus ring 90 shown in fig. 2, except for the position of the dielectric layer 30. Therefore, in fig. 3, the same reference numerals denote the same elements as those in fig. 2, and any further detailed description of the same elements will be omitted hereinafter.

Referring to fig. 3, in a modified focus ring 91, a dielectric layer 30 may be disposed on a composite conductive layer 50, i.e., a second conductive layer 20 may be located between the dielectric layer 30 and a first conductive layer 10. Thus, the plasma may be in direct contact with the dielectric layer 30 during the plasma treatment process.

In detail, the modified focus ring 91 may include a composite conductive layer 50 and a dielectric layer 30 on the composite conductive layer 50. Accordingly, the first conductive layer 10, the second conductive layer 20, and the dielectric layer 30 may be sequentially stacked on one another in the modified focus ring 91.

When heat resistance is required during the plasma treatment process instead of etching resistance, the second conductive layer 20 including silicon carbide (SiC) is exposed to the plasma space, as disclosed in a focus ring 90 shown in fig. 2. In contrast, when etch resistance is required during the plasma treatment process rather than heat resistance, the dielectric layer 30 (e.g., comprising quartz or aluminum oxide (Al)₂O₃) Exposed to the plasma space as disclosed in a modified focus ring 91 shown in fig. 3.

The thickness and material of the dielectric layer 30 may vary depending on the capacitance and etch resistance with respect to the etching plasma in the plasma treatment process. For example, when chlorine (Cl) is used₂) When a plasma etching process is performed using a gas or hydrogen bromide (HBr) gas as a source gas, the dielectric layer 30 may include quartz because of its low cost and good processability.

According to example embodiments of the focus ring, the attenuation of the transmission power signal through the substrate W may be substantially the same as the attenuation of the transmission power signal through the focus ring 90 or the modified focus ring 91, so that the intensity of the electric field caused by the transmission power signal may be uniform from the substrate W to the focus ring. Therefore, the plasma density may also be substantially uniform from the central portion C to the peripheral portion E of the substrate W, and the plasma etching may be uniformly performed over the entire surface of the substrate W.

Fig. 4 is a block diagram illustrating a chuck assembly including the focus ring 90 of fig. 1 and 2 according to an example embodiment. Although fig. 4 shows a chuck assembly including focus ring 90, the chuck assembly may be similarly constructed using focus ring 91 of fig. 3.

Referring to fig. 4, a chuck assembly 500 according to an example embodiment may include a chuck dielectric plate 100, a chuck body 200, a focus ring 90, and an insulation plate 400, the chuck dielectric plate 100 including a first dielectric material and a substrate W may be fixed to the chuck dielectric plate 100, the chuck body 200 supporting the chuck dielectric plate 100 and including a chuck conductive material to which at least one high frequency power may be applied, the focus ring 90 disposed on a peripheral portion of the chuck body 200 and surrounding the substrate W, the insulation plate 400 supporting the chuck body 200. As previously described with reference to fig. 1 and 2, focus ring 90 may include a composite conductive layer 50 and a dielectric layer 30, composite conductive layer 50 being configured as a multi-layered structure having different resistances, dielectric layer 30 being located on at least one of upper surface 51 and lower surface 52 of composite conductive layer 50.

For example, the chucking dielectric plate 100 may include a dielectric bulk disk that may be adhered to the chuck body 200 by an adhesive. The chuck dielectric plate 100 may comprise a ceramic material, such as alumina (Al)₂O₃) Aluminum nitride (AlN) and yttrium oxide (Y)₂O₃)。

The substrate W may be fixed to the chucking dielectric plate 100, and may be subjected to a plasma treatment process, such as a plasma etching process. For example, the substrate W may include a silicon wafer on which a fine pattern structure for a semiconductor device is to be formed, or a glass substrate on which a fine pattern structure for a flat display panel is to be formed.

The chucking dielectric plate 100 may be provided with at least a fixing member SM, and thus the substrate W may be fixed to the chucking dielectric plate 100 by using the fixing member SM. For example, the fixing member SM may include a fixing electrode that may be disposed in the chucking dielectric plate 100 and connected to the external direct current power source DS, for example, the fixing member SM may be a fixing electrode. An electrostatic force may be generated from the electrode, and the substrate W may be fixed to the chucking dielectric plate 100 by the electrostatic force. Accordingly, the chuck assembly 500 may be provided as an electrostatic chuck (ESC) configuration. The fixed electrode may be shaped as one of a ring shape, a semi-circular shape, and a combination of at least two semi-circular shapes.

The fixing member SM may further include a mechanical joint for joining the substrate W to the chucking dielectric plate 100 by using a frictional force. In this example embodiment, the mechanical joint may include a clamp, and the chuck assembly 500 may be provided as a friction chuck structure.

A heating electrode may also be provided in the chucking dielectric plate 100 for heating the substrate W to a predetermined temperature during the plasma etching process. Joule heat may be generated from the heating electrode, and the substrate W may be heated by the joule heat. The heating electrode may be shaped in a concentric circle or a spiral shape with respect to a center point of the disk-shaped chucking dielectric plate 100.

The chuck body 200 may be shaped as a block disk to support the disk-shaped chucking dielectric plate 100, and may include a conductive material, such as aluminum (Al), titanium (Ti), tungsten (W), stainless steel, and combinations thereof. The configuration of the chuck body 200 can vary depending on the requirements of the chuck assembly 500 and the configuration of the plasma processing apparatus having the chuck assembly 500.

In detail, the chuck body 200 may have the step portion 201 of such a configuration: the central portion may protrude higher than the peripheral portion. Thus, the protruding portion 202 of the chuck body 200 can be a central portion of the chuck body 200 that protrudes above the peripheral portion to define the step portion 201 in the periphery of the protruding portion 202 (e.g., around the protruding portion 202). The protruding portion 202 may contact the chucking dielectric plate 100 (e.g., the bottom of the chucking dielectric plate 100), and the step portion 201 of the chuck body 200 may contact the focus ring 90 (e.g., the bottom of the focus ring 90).

When high frequency power is applied to the chuck body 200, the high frequency power may be transmitted to the plasma space above the substrate W through the substrate W and the focus ring 90. Thus, during the plasma treatment process, plasma may be generated in the plasma space and directed towards the substrate W. The high frequency power may include a first power HF1 for generating plasma and a second power HF2 for directing plasma to the substrate W.

The first electrical power HF1 may comprise an Alternating Current (AC) power supply having a frequency of about 10MHz to about 100MHz and may supply sufficient energy to change a source gas in a plasma space above the substrate W into a plasma. In the present example embodiment, the first power HF1 may include a Radio Frequency (RF) power having a frequency of about 13.56 MHz. The second electrical power HF2 may comprise an Alternating Current (AC) power source having a frequency greater than about 1MHz and less than about 10MHz, and may accelerate charged particles of the plasma toward the substrate W. Accordingly, the substrate W may be subjected to a plasma treatment process.

The high frequency power applied to the chuck body 200 may be transmitted as a first transmission power signal TS1 through the protruding portion 202 of the chuck body 200 and the substrate W, and may be transmitted as a second transmission power signal TS2 through the focus ring 90 having the composite conductive layer 50 and the dielectric layer 30. The first transmit power signal TS1 may generate plasma over a central portion C of the substrate W, and the second transmit power signal TS2 may generate plasma over a peripheral portion E of the substrate W.

Accordingly, chuck dielectric plate 100 and substrate W may serve as a first transmission line (e.g., transmission path) for transmitting first transmission power signal TS1 from chuck body 200. The dielectric layer 30 and the composite conductive layer 50 of the focus ring 90 may serve as a second transmission line (e.g., transmission path) for transmitting a second transmission power signal TS2 from the chuck body 200. As shown and described in more detail below with reference to fig. 6A and 6B, respectively, the first and second transmission lines may be referred to as first and second transmission lines TL1 and TL 2.

As shown in fig. 6A and 6B, since each of the first transmission line TL1 (e.g., transmission path) and the second transmission line TL2 (e.g., transmission path) may be configured as a stacked structure of a dielectric material and a conductive material, the applied high-frequency power may be transmitted to the plasma space via a resistor-capacitor (RC) circuit. Accordingly, the applied high-frequency power may be attenuated in relation to an attenuation coefficient of each of the transmission lines TL1 and TL2 (e.g., transmission paths), and the first and second transmission power signals TS1 and TS2 may have different energies on the substrate W and the focus ring 90, respectively.

The focus ring 90 may be configured to be higher than the substrate W in view of erosion in the plasma treatment process. For example, as shown in fig. 4, an upper surface 51 of the focus ring 90 (e.g., an uppermost surface of the second conductive layer 20) may be higher than an upper surface of the substrate W with respect to a bottom of the chuck body 200. Therefore, the length of the second transmission line TL2 (i.e., the total thickness (or height) of the stacked structure of the dielectric layer 30 and the composite conductive layer 50) may be longer than the length of the first transmission line TL1 (i.e., the total thickness (or height) of the stacked structure of the chucking dielectric plate 100 and the substrate W). Therefore, the high frequency power may be attenuated more through the second transmission line TL2 than through the first transmission line TL1, and the strength of the second transmission power signal TS2 may be less than the strength of the first transmission power signal TS 1. As a result, the plasma density on focus ring 90 will be less than the plasma density on substrate W.

The focus ring 90 may include a dielectric layer 30 and a composite conductive layer 50, and the first conductive layer 10 and the second conductive layer 20 having different specific resistances may be disposed in the composite conductive layer 50. Thus, the attenuation through the second transmission line TL2 may be varied by the configuration and properties of the dielectric layer 30 and the composite conductive layer 50. Accordingly, by changing the configuration and properties of the focus ring 90, the intensity of the second transmission power signal TS2 can be made to approach the intensity of the first transmission power signal TS1, and the difference in intensity between the first transmission power signal TS1 and the second transmission power signal TS2 can be minimized by controlling the configuration and properties of the focus ring 90. Note that dielectric layer 30 of focus ring 90 may be referred to as a ring dielectric layer for comparison with chuck dielectric plate 100.

When alternating-current power is applied to the RC circuit, energy loss occurs in the RC circuit with respect to transmission loss caused by the resistance of the RC circuit and time delay caused by the resistance and capacitance of the RC circuit. The transmission loss is typically detected as a conductor loss at a surface area of a resistor of the RC circuit, and the time delay may be detected as a phase difference at the resistor and a capacitor of the RC circuit.

In the present exemplary embodiment, the chuck dielectric plate 100 and the ring dielectric layer 30 of the focus ring 90 may be configured to have the same capacitance.

Energy loss in alternating-current power transmission is mainly caused by conductor loss rather than phase difference, and the capacitance of the RC circuit has a larger influence on the phase difference rather than the resistance of the RC circuit. Accordingly, when the chucking dielectric plate 100 and the ring dielectric layer 30 have the same capacitance, the phase difference of the second transmission power signal TS2 may approach the phase difference of the first transmission power signal TS 1.

Thus, the energy loss caused by the phase difference may be substantially the same between the first power signal TS1 and the second power signal TS2, and the difference in strength between the first power signal TS1 and the second power signal TS2 may be primarily determined by the conductor losses of the first transmission line TL1 and the second transmission line TL 2. That is, by experimentally determining the resistance of the composite conductive layer 50 of the focus ring 90 in such a manner that the conductor loss of the second transmission power signal TS2 may be close to the conductor loss of the first transmission power signal TS1, the intensity difference between the first power signal TS1 and the second power signal TS2 may be minimized.

Fig. 5 is a plan view illustrating the chuck dielectric plate 100 and the ring dielectric layer 30 of the focus ring 90 in the chuck assembly shown in fig. 4.

Referring to fig. 5, the ring dielectric layer 30 may be disposed on the step portion 201 of the chuck body 200, and may be shaped as a ring surrounding the chuck dielectric plate 100. Accordingly, when the gap between the ring dielectric layer 30 and the chucking dielectric plate 100 is negligible, the chucking dielectric plate 100 may have a chucking radius r_cAnd the ring dielectric layer 30 may have a ring radius r₃。

When the chucking dielectric plate 100 has a chucking thickness t_cDielectric constant of chuck ∈_cAnd surface area A_cAnd the ring dielectric layer 30 has a third thickness t₃Ring dielectric constant ε₃And the ring surface area A₃The capacitances of the chucking dielectric plate 100 and the ring dielectric layer 30 can be obtained as in the following equations (1) and (2), respectively. In the following equations (1) and (2), C_cRepresents the capacitance of chuck dielectric plate 100, and C₃Representing the capacitance of the ring dielectric layer 30.

Accordingly, the third thickness t of the ring dielectric layer 30₃The capacitance C of the dielectric ring layer 30 can be made₃Capacitance C that can be coupled to chuck dielectric plate 100_cSubstantially the same such manner is obtained by the following equation (3).

Specifically, when the chucking dielectric plate 100 and the ring dielectric layer 30 include the same dielectric material, the third thickness t of the ring dielectric layer 30₃May be less than the thickness of chucking dielectric plate 100. For example, the ring dielectric layer 30 may include aluminum oxide (Al)₂O₃) Quartz, yttrium oxide (Y)₂O₃) And combinations thereof.

Fig. 6A is a perspective view illustrating a first transmission line (e.g., transmission path) TL1 in which the chucking dielectric plate 100 and the substrate W are stacked. Fig. 6B is a perspective view illustrating a second transmission line (e.g., transmission path) TL2 in which the ring dielectric layer 30 and the composite conductive layer 50 are stacked.

Referring to fig. 4, 6A and 6B, high frequency power may be applied to the chuck body 200 and transmitted to a plasma space above the substrate W through the first transmission line TL1 at the central portion C of the chuck body 200 and the second transmission line TL2 at the peripheral portion E of the chuck body 200. Thus, the high frequency power may be converted into a first transmission power signal TS1 over the substrate W and a second transmission power signal TS2 over the focus ring 90.

In this case, the intensity of the first transfer power signal TS1 above the substrate W may be obtained as in equation (4) below. The intensity of the second transmission power signal TS1 above the focus ring 90 can be obtained as the following equation (5).

In the above equations (4) and (5), z is a position along the height direction of the chuck assembly 500, x is a position along the radial direction of the chuck assembly 500, t is an arbitrary time after the high-frequency power HF1 is applied to the chuck body 200, ω is an angular velocity of the high-frequency power HF1, S₁And S₂Respectively a first intensity and a second intensity, alpha₁And alpha₂Attenuation coefficients of the first transmission line TL1 and the second transmission line TL2, respectively, and beta₁And beta₂The phase coefficients of the first transmission line TL1 and the second transmission line TL2, respectively. Any internal position of the transmission line may be determined by a coordinate in the radial direction x, such that the position of the skin depth of the transmission line may be determined by the x-coordinate value. For example, S₀Represents the initial intensity of the high-frequency power HF1 at the time when the high-frequency power HF1 is applied to the chuck body 200, and S_1xRepresenting any strength of the first transmission power signal TS1 at any time and at any radial position x of the first transmission line TL 1. In the same way, S_2xRepresenting an arbitrary strength of the second transmission power signal TS2 at an arbitrary time and at an arbitrary radial position x of the second transmission line TL 2.

Although the transmission loss of the high-frequency power HF1 occurs along the radial direction x of the chuck assembly 500 and the height direction z of the chuck assembly 500, the transmission loss along the radial direction x does not have an influence on the generation of plasma over the substrate W. Therefore, in order to minimize the difference in intensity between the first and second transmission power signals TS1 and TS2, the transmission loss along the radial direction x is negligible.

Thus, the strength of the first transmission power signal TS1 may be mainly determined by the attenuation coefficient α of the first transmission line TL1₁And (4) determining. The strength of the second transmission power signal TS2 may be mainly determined by the attenuation coefficient α of the second transmission line TL2₂And (4) determining.

Therefore, when the attenuation coefficient α of the first transmission line TL1 is₁Attenuation coefficient alpha with the second transmission line TL2₂Substantially the same, first transmissionThe difference in strength between the power signal TS1 and the second transmission power signal TS2 may be minimized. As a result, the uniformity of the plasma density in the plasma space can be increased.

The attenuation coefficient α is generally expressed as the following equation (6). In equation (6), B is a constant determined according to the dielectric constant and the magnetic permeability of the transmission line, f is the frequency of the high-frequency power transmitted through the transmission line, ω is the angular velocity of the high-frequency power, and ρ is the specific resistance of the transmission line.

In the present exemplary embodiment, since the same high-frequency power may be applied to the first and second transmission lines TL1 and TL2, the angular velocity of the high-frequency power may be the same in the first and second transmission lines TL1 and TL 2. Thus, the attenuation coefficient α of the first transmission line TL1 and the second transmission line TL2₁And alpha₂May be inversely proportional to the square root of the specific resistance p of the corresponding transmission line.

Thus, when the composite conductive layer 50 of the focus ring 90 has a sufficiently large specific resistance, the attenuation coefficient α of the second transmission line TL2₂Can be sufficiently reduced. Accordingly, the strength of the second transmission power signal TS2 may approach the strength of the first transmission power signal TS 1.

The focus ring 90 may be shaped as a ring that is disposed on the stepped portion 201 of the chuck body 200 and surrounds the substrate W with a thickness greater than that of the substrate W. Thus, it may be difficult for the focus ring 90 to have a uniform specific resistance along the entire body. For this reason, the conductive material of the focus ring 90 may be configured into the first conductive layer 10 having a relatively small thickness and a small specific resistance and the second conductive layer 20 having a relatively large thickness and a large specific resistance. Accordingly, focus ring 90 may include a composite conductive layer 50 including first conductive layer 10 and second conductive layer 20.

Since the specific resistance of the first conductive layer 10 is relatively small and thus the attenuation coefficient α of the first conductive layer 10 is relatively large as shown in equation (6), a relatively large amount of conductor loss may occur at the first conductive layer 10 when the high-frequency power HF1 is transmitted through the focus ring 90. In contrast, since the specific resistance of the second conductive layer 20 is relatively large and thus the attenuation coefficient α of the second conductive layer 20 is relatively small as shown in equation (6), a relatively small amount of conductor loss may occur at the second conductive layer 20 when the high-frequency power HF1 is transmitted through the focus ring 90. Specifically, the second conductive layer 20 may have such a configuration that substantially no attenuation occurs at the second conductive layer 20.

Accordingly, attenuation of the high-frequency power HF1 at the chuck dielectric plate 100 and the ring dielectric layer 30 may be negligible, and most of the attenuation of the high-frequency power HF1 may occur at the substrate W and the first conductive layer 10 of the focus ring 90. When the high-frequency power HF1 is transmitted through the chuck assembly 500 in the height direction z, the total attenuation of the high-frequency power HF1 at the substrate W can be obtained by the following equation (7), and the total attenuation of the high-frequency power HF1 at the first conductive layer 10 can be obtained by the following equation (8).

Thus, the first thickness t of the first conductive layer 10 can be determined in this way₁: so that the total attenuation of the high-frequency power HF1 at the substrate W can be as close as possible to the total attenuation of the high-frequency power HF1 at the first conductive layer 10, as represented in equation (9).

Therefore, when the conductive material of the first conductive layer 10 is selected and thus the specific resistance of the first conductive layer 10 is determined, the first thickness t of the first conductive layer 10 can be obtained by the above equation (9)₁. I.e. when the first thickness t of the first conductive layer 10 is₁When equation (9) is satisfied, the substrate W andthe difference in intensity between the first transmitted power signal TS1 and the second transmitted power signal TS2 is minimized across the focus ring 90.

In this case, the second conductive layer 20 may have a larger specific resistance than the first conductive layer 10, so that substantially no attenuation occurs in the second conductive layer 20. For example, the specific resistance of the second conductive layer 20 may be about 10 times to about 100 times that of the first conductive layer 10. Accordingly, the intensity of the second transmission power signal TS2 may be substantially the same as the intensity of the high frequency power HF1 transmitted through the first conductive layer 10.

Due to the third thickness t of the ring dielectric layer 30₃Can be obtained by equation (3), and the first thickness t of the first conductive layer 10₁Can be obtained by equation (9), the second thickness t of the second conductive layer 20₂Can be used as the total thickness T and the first thickness T of the focus ring 90₁And a third thickness t₃Is obtained as described in equation (10) below. The total thickness T of the focus ring 90 may be set to the specification of the chuck assembly 500 according to the requirements of the plasma processing process and the chamber characteristics of the plasma processing apparatus having the chuck assembly 500.

t₂＝T-(t₁+t₃) (10)

In the present exemplary embodiment, the substrate W may include a silicon wafer, and the first conductive layer 10 may include silicon (Si), so that the first conductive layer 10 may have the same thickness as that of the substrate W. Further, second conductive layer 20 may include a high resistance conductive material, such as silicon carbide (SiC), and the total thickness T of focus ring 90 may be in the range of about 3mm to about 6 mm.

First thickness t obtained from equation (9)₁Is based on the following assumptions: the transmission loss along the radial direction x of the second transmission line TL2 and the phase difference caused by the resistance are negligible, so that the strength of the second transmission power signal TS2 may deviate slightly from the actual strength of the second transmission power signal TS 2.

Accordingly, the first thickness t of the first conductive layer 10₁And a first specific resistance ρ₁Can be experimentally obtained by simulation based on equations (4) and (5).Accordingly, the intensity of the second transmission power signal TS2 may become closer to the intensity of the first transmission power signal TS1, thereby more accurately minimizing the difference in intensity between the first transmission power signal TS1 and the second transmission power signal TS 2.

Fig. 7 is a graph illustrating a relationship between the specific resistance of the first conductive layer 10 of the focus ring 90 and the intensity difference between the first transmission power signal TS1 and the second transmission power signal TS2 for various thicknesses of the first conductive layer 10. In fig. 7, according to having a specific first thickness t₁Shows a change in the intensity difference, and a plurality of first conductive layers 10 having different specific resistances are provided for simulation to detect the relationship between the specific resistance and the intensity difference. Assuming that the first conductive layer 10 is made of a material having the same magnetic permeability as the dielectric constant, for the first thickness t thereof₁Three simulations were performed with three first conductive layers 10 set to about 2mm, 3mm, and 4mm, respectively.

As shown in fig. 7, the intensity difference between the first transmission power signal TS1 and the second transmission power signal TS2 is minimized at a specific point of the specific resistance of each of the first conductive layers 10. When the first thickness t of the first conductive layer 10₁Is about 2mm, the intensity difference is minimized at the first minimum point MP1, and when the first thickness t of the first conductive layer 10₁At about 3mm, the intensity difference is minimized at the second minimum point MP 2. In the same manner, when the first thickness t of the first conductive layer 10 is larger₁At about 4mm, the intensity difference is minimized at the third minimum point MP 3. Among the three minimum points MP1, MP2 and MP3, when the first thickness t is₁At about 2mm, the strength difference is minimal.

Therefore, the simulation result in fig. 7 shows that both specific resistance and thickness are obtained at the minimum point where the intensity difference is minimized. Hereinafter, the specific resistance and the thickness at the minimum point where the intensity difference is minimum are referred to as a minimum specific resistance and a minimum thickness. Therefore, when the first conductive layer 10 can be configured to have the minimum specific resistance and the minimum thickness as the first specific resistance ρ₁And a first thickness t₁The difference in intensity between the first and second transmission power signals TS1 and TS2 may be between the substrates W and SAbove the focus ring 90. In the present exemplary embodiment, when the first conductive layer 10 has the first thickness t of about 2mm₁A first specific resistance p of about 25. omega. cm₁When the first transmission power signal TS1 and the second transmission power signal TS2 are combined, the intensity difference between them may be minimized.

According to the above simulation, the intensity of the first transmission power signal TS1 and the intensity of the second transmission power signal TS2 can be individually calculated by using a computer system, and the arithmetic difference between the intensities can be obtained at each specific resistance. Therefore, the transmission loss in the radial direction and the phase difference caused by the resistance, which can be ignored for the effectiveness of equation (9), can be reflected in the result of the computer simulation shown in fig. 7.

Thus, the first thickness t of the first conductive layer 10 is determined by computer simulation₁And a first specific resistance ρ₁The first thickness t of the first conductive layer 10, which can be calculated from equation (9)₁And a first specific resistance ρ₁The intensity difference is reduced even more.

Third thickness t of the ring dielectric layer 30₃Can be obtained by equation (3), and the first thickness t of the first conductive layer 10₁Can be obtained by simulation results as shown in fig. 7, and then the second thickness t of the second conductive layer 20₂Can be determined by equation (10).

For example, the insulating plate 400 may be disposed under the chuck body 200 and may support the chuck body 200. The insulating plate 400 may have a surface area corresponding to the chuck body 200 such that the chuck body 200 may be supported by the insulating plate 400 (e.g., completely supported by the insulating plate 400). Accordingly, the chuck body 200 may be sufficiently insulated from the ground plate, which may be disposed at the lower portion of the chuck assembly 500, by the insulating plate 400. Specifically, the insulating plate 400 may be configured to have a shape and material that may minimize capacitance between the chuck body 200 and the insulating plate 400.

The insulating plate 400 may include a single insulator or a multi-layered structure having at least two insulating layers having different dielectric constants. Therefore, the leakage current through the insulating plate 400 can be sufficiently prevented, and the plasma density does not deteriorate with time.

The shield ring SR may extend from the insulating plate 400 in such a configuration that a side surface of the chuck body 200 and a side surface of the focus ring 90 may be surrounded by the shield ring SR. The shield ring SR can have a sufficiently large dielectric constant such that sufficient impedance can be present between the chuck body 200 and the shield ring SR, and thus the high frequency power HF1 can be prevented from being lost toward the sides of the chuck assembly 500. For example, the shield ring SR may include a dielectric material having a dielectric constant of less than about 5, such as quartz, silicon carbide (SiC), and silicon oxide (SiO)₂)。

In addition, since the shield ring SR may surround the chuck body 200 and the focus ring 90. Accordingly, the chuck body 200 and the focus ring 90 can be sufficiently prevented from being damaged by plasma, residual source gas, and various particles of the plasma processing process.

The ground plate may also be disposed under the insulating plate 400. The ground plate may be shaped in the same shape as the insulating plate 400 such that the ground plate may be covered by the insulating plate 400 (e.g., completely covered by the insulating plate 400). The high frequency power HF1 may be applied to the chuck body 200 via power lines penetrating a ground plate.

Although the present exemplary embodiment discloses that the collar dielectric layer 30 may be disposed under the first conductive layer 10, the collar dielectric layer 30 may also be disposed on the second conductive layer 20 as described in detail with reference to fig. 3, according to the requirements of the plasma treatment process.

According to an exemplary embodiment of chuck assembly 500, first thickness t of first conductive layer 10 of focus ring 90₁And a first specific resistance ρ₁May be obtained by theoretical calculation or by computer simulation in such a way that the difference in intensity between the first transmitted power signal TS1 and the second transmitted power signal TS2 may be minimized. Therefore, when the substrate W may be subjected to the plasma etching process, the density of plasma over the substrate W may be sufficiently uniform throughout the substrate W, thereby improving the etching uniformity of the substrate W from the central portion to the peripheral portion.

Fig. 8 is a block diagram illustrating a plasma processing apparatus having the chuck assembly 500 of fig. 4 according to an example embodiment.

Referring to fig. 8, a plasma processing apparatus 1000 according to an example embodiment may include a process chamber 600 having a process space PS in which a plasma processing process may be performed, a source supplier 700 disposed at an upper portion of the process chamber 600 and supplying a source gas G for the plasma processing process, a chuck assembly 500 disposed at a lower portion of the process chamber 600 and clamping a substrate W to be processed by the plasma processing process, and a power supply 800 applying at least one high frequency power to the chuck assembly 500 and generating a plasma for the plasma processing process in the process space PS. Hereinafter, the processing space PS of the process chamber 600 may be generally referred to as a plasma space because plasma for a plasma processing process is generated in the processing space above the substrate W.

The chuck assembly 500 of the plasma processing apparatus 1000 may have substantially the same structure as that described in detail with reference to fig. 4 to 7. Therefore, in fig. 8, the same reference numerals denote the same elements as those in fig. 4 to 7, and any further detailed description of the same elements will be omitted hereinafter.

Referring to fig. 8, the process chamber 600 may include a three-dimensional structure having a process space PS therein and have sufficient strength and rigidity for a plasma processing process. In this example embodiment, the process chamber 600 may include a bottom 601, a top plate 602 opposite the bottom 601, and a plurality of sidewalls 603 between the bottom 601 and the top plate 602.

A door 610 may be provided to one of the sidewalls 603, and the substrate W may be loaded into the process chamber 600 or unloaded from the process chamber 600 through the door 610. The chuck assembly 500 may be disposed on the bottom 601 of the process chamber 600, and the substrate W may be fixed to the chuck assembly 500.

In detail, the chuck assembly 500 may be disposed on a central portion of the bottom 601 of the process chamber 600, and a plurality of discharge holes DH may be disposed through the bottom 601 around the chuck assembly 500. The residual gas and by-products of the plasma treatment process may be exhausted from the process chamber 600 through the exhaust hole DH.

The collection chamber 900 may be disposed below the processing chamber 600 and communicate with the processing chamber 600 via the exhaust hole DH such that residual gases and byproducts of the plasma treatment process may be collected in the collection chamber 900. The pump structure 910 may be disposed at a lower portion or a side portion of the collection chamber 900 and may force residual gases and byproducts of the plasma treatment process to be exhausted from the treatment chamber 600. In the present example embodiment, the pump structure 910 may include a flow control valve V and a vacuum pump P.

Although the present exemplary embodiment discloses that the process chamber 600 is provided as an entire housing having a single door 610 for loading and unloading the substrate W, any other configuration may be embedded in the process chamber according to the characteristics of the plasma processing apparatus. For example, the process chamber 600 may include a lower case and an upper case that may be combined with each other. Accordingly, when the substrate W is loaded into the process chamber 600 or unloaded from the process chamber 600, the lower and upper housings may be separated from each other, and the process space PS may be exposed to the ambient environment. In contrast, when the plasma treatment process is performed in the process chamber 600, the upper and lower housings may be combined with each other in a structure in which the processing space PS may be separated from the surrounding environment.

In the present exemplary embodiment, the plasma treatment process may include a plasma etching process by which a source gas may be changed into plasma in the processing space PS, and the substrate may be subjected to the etching process by using the plasma. However, any other plasma processing process may be performed in the plasma processing apparatus 1000 as long as the focus ring is disposed around the substrate W and high frequency power is applied to the chuck assembly 500 to generate plasma in the processing space PS of the process chamber 600.

For example, the source supplier 700 may be disposed at an upper portion of the process chamber 600 facing away from the chuck assembly 500. The source supplier 700 may include a gas supplier 710, a source line 720, and a source canister 730, the gas supplier 710 supplying a source gas G into the process space PS through a plurality of supply holes SH, the source line 720 transferring the source gas G to the gas supplier 710, and the source canister 730 disposed at the outside of the process chamber 600 and connected to the source line 720.

The gas supplier 710 may be shaped in a cubic structure having a size larger than that of the substrate W so that the substrate W may be sufficiently covered by the gas supplier 710. An upper portion of the gas supplier 710 may be connected to the source line 720, and a plurality of supply holes SH may be disposed at a lower portion of the gas supplier 710 facing the process space PS. Accordingly, the source gas G may be transferred into the gas supplier 710 through the source line 720, and may be uniformly supplied into the process space PS through the plurality of supply holes SH. In the present exemplary embodiment, the gas supplier 710 may include a showerhead having a size to sufficiently cover the substrate W.

The source gas G may vary depending on the characteristics and requirements of the plasma treatment process. For example, the source gas G may include chlorine fluoride (Cl)_xF_y) Chlorine (Cl)₂) Gas, hydrogen bromide (HBr), and the like.

The chuck assembly 500 may be disposed on the bottom of the process chamber 600, and the substrate W may be fixed to the chuck assembly 500. Accordingly, the process space PS may be disposed between the substrate W and the gas supplier 710. The source gas G may be supplied into the process space PS and changed into plasma over the substrate W for a plasma treatment process in the process space PS, so that the process space PS may be used as a plasma space in which plasma may be generated. First high frequency power HF1 may be applied to chuck assembly 500 to generate a plasma, and second high frequency power HF2 may be applied to chuck assembly 500 to direct the plasma onto substrate W.

The chuck assembly 500 can include a composite conductive layer 50 and a ring dielectric layer 30 on or below the composite conductive layer 50. The composite conductive layer 50 may include a first conductive layer 10 having a relatively small thickness and a relatively small specific resistance and a second conductive layer 20 having a relatively large thickness and a relatively large specific resistance.

The first high-frequency power HF1 may be transmitted to the process space PS or the plasma space as a first transmission power signal TS1 through a first transmission line TL1 including the chuck dielectric plate 100 and the substrate W, and transmitted to the process space PS or the plasma space as a second transmission power signal TS2 through a second transmission line TL2 including the focus ring 90. In this case, the intensity difference between the first and second transmission power signals TS1 and TS2 may be minimized by controlling the thickness and specific resistance of the first conductive layer 10 of the focus ring 90.

Since the intensity difference can be minimized over the substrate W, the density of the plasma can be uniform from the central portion to the peripheral portion of the substrate W, thereby sufficiently increasing the plasma uniformity throughout the substrate W.

The power supply 800 may be disposed at the exterior of the process chamber 600 and may be connected to the chuck body 200 of the chuck assembly 500. For example, the power supply 800 may include a first power supply 810, a second power supply 820, and a third power supply 830, the first power supply 810 for generating a first high frequency power HF1 and applying a first high frequency power HF1 to the chuck body 200 to change the source gas into plasma for the plasma treatment process in the process space PS, the second power supply 820 for generating a second high frequency power HF2 and applying a second high frequency power HF2 to the chuck body 200 to guide charged particles of the plasma onto the substrate W in the process space PS, the third power supply 830 for generating a Direct Current (DC) power and applying the DC power to a fixed electrode in the chuck dielectric plate 100 to fix the substrate W to the chuck dielectric plate 100.

The first power supply 810 may include a first AC generator 811 and a first impedance matcher 813. The first AC generator 811 may generate the first high-frequency power HF1, and the first impedance matcher 813 may include a transformer and a plurality of matching circuits for synchronizing impedance between the first AC generator 811 and the chuck body 200.

The first high-frequency power HF1 may include alternating current power having a frequency of about 10MHz to about 100MHz and may be transmitted to the processing space PS through a first transmission line TL1 as a first transmission power signal TS1 and transmitted to the processing space PS through a second transmission line TL2 as a second transmission power signal TS 2. In the present example embodiment, the intensity difference between the first and second transmission power signals TS1 and TS2 may be minimized by controlling the thickness and permittivity of the ring dielectric layer 30 and the thickness and specific resistance of the first conductive layer 10.

The source gas G may be changed into active ions and radicals in the processing space PS by the first and second transmission power signals TS1 and TS2, so that plasma for the plasma processing process may be generated in the processing space PS by the first and second transmission power signals TS1 and TS 2. In the present example embodiment, the plasma may include an etching plasma for patterning or etching a thin layer on the substrate W.

The second power supply 820 may include a second AC generator 821 and a second impedance matcher 823. The second AC generator 821 may generate the second high-frequency power HF2, and the second impedance matcher 823 may include a transformer and a plurality of matching circuits for synchronizing impedance between the second AC generator 821 and the chuck body 200.

Specifically, the frequency of the second high-frequency power HF2 may be about 0.01 times to about 0.1 times the frequency of the first high-frequency power HF 1. Therefore, the second high-frequency power HF2 may include alternating-current power having a frequency of about 1MHz to about 10 MHz. The active ions and radicals of the plasma may be accelerated onto the substrate W by the second high-frequency power HF2, and the substrate W may be subjected to a plasma treatment process by the plasma.

Since the attenuation coefficient is proportional to the square root of the frequency as shown in equation (6), and the frequency of the second high-frequency power HF2 may be about 0.01 times to about 0.1 times the frequency of the first high-frequency power HF1, the attenuation of the second high-frequency power HF2 may be negligible when compared with the attenuation of the first high-frequency power HF 1. Accordingly, the second high-frequency power HF2 can be uniformly transmitted to the processing space PS, and thus the active ions and radicals of the plasma can be uniformly accelerated onto the substrate W from the central portion C to the peripheral portion E.

Third power supply 830 may apply DC power to the fixed electrodes in chucking dielectric plate 100. An electrostatic force may be generated from the fixed electrode, and the substrate W may be fixed to the chucking dielectric plate 100 of the chuck assembly 500.

According to the present exemplary embodiment of the plasma processing apparatus, the transmission loss of the second transmission power signal TS2 may be made close to the transmission loss of the first transmission power signal TS1 by controlling the dielectric constant and thickness of the ring dielectric layer 30 and the thickness and specific resistance of the first conductive layer 10 of the focus ring 90. Accordingly, the intensity difference between the first transmission power signal TS1 and the second transmission power signal TS2 may be minimized in the plasma processing apparatus 1000, thereby improving the uniformity of the plasma processing process on the substrate W.

According to example embodiments, the focus rings 90 and 91 for focusing plasma on the substrate W may include a composite conductive layer 50 and a dielectric layer 30, wherein the composite conductive layer 50 includes a first conductive layer 10 having a relatively small thickness and a relatively small specific resistance and a second conductive layer 20 having a relatively large thickness and a relatively large specific resistance. The dielectric layer 30 may have a thickness and a dielectric constant such that: such that the capacitance of the dielectric layer may be substantially the same as the capacitance of the chuck dielectric plate to which the substrate is secured. The first conductive layer of the focus ring may have a thickness and a specific resistance such that: such that the attenuation of the second transmitted power signal transmitted through the focus ring may be close to the attenuation of the first transmitted power signal transmitted through the chucking dielectric plate and the substrate. The second conductive layer of the focus ring may have a specific resistance such that a transmission loss does not occur when high frequency power may be transmitted through the second conductive layer.

Accordingly, the intensity difference between the first transmission power signal TS1 and the second transmission power signal TS2 may be minimized in the plasma processing apparatus 1000, thereby improving the uniformity of the plasma processing process on the substrate W. In particular, when a large-diameter substrate W (e.g., a wafer) is subjected to a plasma treatment process, a difference in plasma density may be significant between the central portion C and the peripheral portion E of the substrate W. However, according to the present exemplary embodiment of the chuck assembly and the plasma processing apparatus, the plasma density may become sufficiently uniform from the central portion C to the peripheral portion E of the substrate W.

By way of summary and review, when high frequency power is applied to the chuck assembly and transmitted to the plasma space via the chuck and substrate and via the focus ring, the time delay and decay of the high frequency power may be different when transmitted through the chuck and when transmitted through the focus ring. For example, since the focus ring is made of a material different from the materials of the substrate and the chuck, and since the focus ring is constructed in a structure different from the structures of the substrate and the chuck, the time delay and attenuation of the high frequency power may be different when the high frequency power is transmitted to the substrate via the central portion of the chuck assembly including the chuck and when the high frequency power is transmitted to the peripheral portion of the chuck assembly including the focus ring.

Since the focus ring generally has a thickness greater than that of the substrate, the attenuation of the high-frequency power at the focus ring is greater than that at the substrate in consideration of erosion of the plasma process. Therefore, the electric field strength generated in the plasma space by the high-frequency power is much smaller around the focus ring than around the substrate. Therefore, the plasma density is much less over the focus ring than over the substrate, which may cause process defects at the peripheral portion of the substrate during the plasma process.

Accordingly, there has been a need for an improved focus ring in which a difference in electric field strength between a substrate and the focus ring can be minimized when high frequency power is applied to a chuck assembly. Accordingly, example embodiments provide a focus ring on which a composite conductive layer including a high resistance layer and a low resistance layer and a dielectric layer are stacked one on another, thereby minimizing a difference in strength of an electric field generated by high frequency power between a substrate and the focus ring. Example embodiments also provide a chuck assembly for a plasma processing process having the above focus ring and a plasma processing apparatus including the above chuck assembly.

Example embodiments have been disclosed herein and, although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purposes of limitation. In some instances, features, characteristics and/or elements described in connection with a particular embodiment may be used alone, or in combination with features, characteristics and/or elements described in connection with other embodiments, as will be apparent to one of ordinary skill in the art, as of the filing of the present application, unless otherwise specifically noted. It will therefore be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.