阅读说明：本技术 用于晶圆等离子体刻蚀的方法和设备 (Method and apparatus for wafer plasma etching ) 是由 周云 解文骏 睢智峰 于 2019-02-14 设计创作，主要内容包括：本发明提供一种用于晶圆等离子体刻蚀的方法和设备,包括腔体,等离子体产生装置,进气环装置,晶圆加热盘,晶圆旋转装置,磁铁盘装置和屏蔽结构；所述等离子体装置在腔体内产生感应耦合等离子体,所述进气环装置,采用圆环状结构,在圆环内壁有多个出气口,改善工艺气体分布的均匀性；所述晶圆放置在加热盘装置上并通过晶圆旋转装置实现晶圆旋转,所述加热盘的内部装有磁铁盘装置,形成一个额外的磁场,并以此来改善晶圆刻蚀的均匀性。屏蔽结构设置在腔体顶部、靠近介质罩的位置,用于对介质罩的内表面进行部分屏蔽,以避免金属反溅物在介质罩的内壁上形成连续金属镀层,从而保证射频能量耦合和刻蚀工艺的稳定性。(The invention provides a method and equipment for wafer plasma etching, which comprises a cavity, a plasma generating device, an air inlet ring device, a wafer heating plate, a wafer rotating device, a magnet plate device and a shielding structure, wherein the plasma generating device is arranged on the cavity; the plasma device generates inductively coupled plasma in the cavity, the air inlet ring device adopts a circular ring structure, and a plurality of air outlets are formed in the inner wall of the circular ring, so that the uniformity of process gas distribution is improved; the wafer is placed on the heating disc device, the wafer is rotated through the wafer rotating device, the magnet disc device is arranged inside the heating disc, an additional magnetic field is formed, and therefore the etching uniformity of the wafer is improved. The shielding structure is arranged at the top of the cavity and close to the medium cover and is used for partially shielding the inner surface of the medium cover so as to prevent metal back-splashed objects from forming a continuous metal coating on the inner wall of the medium cover, and therefore the stability of radio frequency energy coupling and etching processes is ensured.)

1. A method for carrying on the plasma body to the crystal circle and etching, the radio frequency power is exerted to the induction coil through the matching network, and produce the inductive coupling plasma body in the cavity through the medium cover, etch the crystal circle on the surface of heating plate with the plasma body, remove the natural oxide layer or other substances on the surface of crystal circle; the cavity is internally provided with an air inlet ring device, and the inner wall of the air inlet ring is provided with a plurality of air outlets;

the cavity is internally provided with a shielding structure, and the shielding structure is arranged at the top of the cavity and close to the medium cover and is used for partially shielding the inner surface of the medium cover.

2. The method as claimed in claim 1, wherein the gas inlet ring device is of a circular ring structure, a plurality of gas outlets are formed in the inner wall of the circular ring, and gas inlets are formed in two ends of the outer side of the circular ring, so that the uniformity of the distribution of the process gas is improved.

3. The method of any one of claims 1 to 2, wherein the chamber has a heating plate arrangement therein, wherein the wafer tray rests on the heating plate arrangement.

4. The method as claimed in any one of claims 1 to 3, wherein the chamber has a wafer rotation device therein for continuous or discontinuous wafer rotation.

5. The method as claimed in claim 4, wherein the wafer rotating device has a ring shape at the upper end, has four supporting points and is distributed at 90 degrees; the rotary supporting rod is arranged below the rotary supporting rod and connected with the soft magnet at the bottom of the cavity, the soft magnet and the permanent magnet are correspondingly placed on the inner side and the outer side of the bottom of the cavity, and the wafer tray is rotated through the rotation of the outer permanent magnet.

6. The method as claimed in claim 4 or 5, wherein the wafer rotating device can also adopt a design of a rotatable top shaft and a bellows moving up and down, or adopt a magnetic fluid rotary seal mode.

7. A method as claimed in any one of claims 1 to 6, wherein the chamber has a magnet disc means, which may be a permanent magnet or an electromagnet, in a continuously rotating manner, within the chamber.

8. The method according to any one of the preceding claims 1 to 7, wherein the heating disk device comprises a magnet disk, a heating wire, a bellows and a motor, wherein the magnet disk and the heating wire are arranged inside the heating disk device, and the heating disk device is fixed with the cavity wall through the bellows; the motor is connected with the magnet disc through a belt, a gear and a rotating shaft outside the cavity to drive the magnet disc to rotate.

9. A method according to any one of the preceding claims 1 to 8, wherein the shielding structure is a metal cage of hemispherical or near hemispherical shape.

10. The method according to any of the preceding claims 1 or 9, wherein the shielding structure comprises a plurality of indentations.

11. A method according to any preceding claim, wherein the heating means is configurable with heating means controllable to a temperature in the range-20 ℃ to 550 ℃.

12. The method as claimed in any one of the preceding claims, wherein the wafer material is a semiconductor, quartz or ceramic material, and the wafer surface has a natural oxide layer or a metal layer.

13. A method according to any preceding claim, wherein the plasma etching is used to etch a native oxide layer or other material such as metal on the surface of a wafer having a diameter of 100 mm or more.

14. A method according to any of the preceding claims, wherein the pallet is loaded with a radio frequency power supply 2, and a negative bias is formed on the pallet.

15. The method of any preceding claim, wherein the radio frequency power supply frequency is in the range 400KHz to 27 MHz.

16. An apparatus for plasma etching a wafer, comprising:

a cavity;

the inductively coupled plasma generating device comprises an induction coil, a radio frequency power supply 1 and a medium cover;

the inner wall of the air inlet ring is provided with a plurality of air outlets;

and the shielding structure is arranged at the top of the cavity and close to the medium cover and is used for partially shielding the inner surface of the medium cover.

17. The apparatus of claim 16, wherein the air inlet ring is circular, a plurality of air outlets are formed on the inner wall of the circular ring, and air inlets are formed at two ends of the outer side of the circular ring.

18. The apparatus of claim 16 or 17, wherein the chamber has a heating plate device therein, wherein the wafer tray is placed on the heating plate device, and the heating plate device can control the temperature in a partitioned manner.

19. The apparatus of any one of claims 16 to 18, wherein the chamber has a wafer rotation device therein for continuous or discontinuous wafer rotation.

20. The apparatus as claimed in claim 19, wherein the wafer rotating device has a ring shape at the upper end, and has four supporting points distributed at 90 °; the rotary supporting rod is arranged below the rotary supporting rod and connected with the soft magnet at the bottom of the cavity, the soft magnet and the permanent magnet are correspondingly placed on the inner side and the outer side of the bottom of the cavity, and the wafer tray is rotated through the rotation of the outer permanent magnet.

21. The apparatus as claimed in claim 19 or 20, wherein the wafer rotating device can also adopt a design of a rotatable top shaft plus a bellows moving up and down, or adopt a magnetic fluid rotary seal mode.

22. Apparatus according to any one of claims 16 to 21, wherein the chamber has a magnet disc means inside, the magnet disc means being either a permanent magnet or an electromagnet, or a combination of a permanent magnet and a soft magnet, in a continuously rotating manner.

23. The apparatus as claimed in any one of claims 16 to 22, wherein the heating disk means comprises a magnet disk, a heater wire, a bellows and a motor, the magnet disk and the heater wire being mounted inside the heating disk means, the heating disk means being secured to the chamber wall by the bellows; the motor is connected with the magnet disc through a belt, a gear and a rotating shaft outside the cavity to drive the magnet disc to rotate.

24. The apparatus of any one of the preceding claims 16 to 23, wherein the shielding structure is a metal cage of hemispherical or near hemispherical shape.

25. The apparatus of any preceding claim 16 or 24, wherein the shielding structure comprises a plurality of indentations.

26. The apparatus of any preceding claim 16 to 25, wherein the heating means is configurable with heating means controllable to a temperature in the range-20 ℃ to 550 ℃.

27. The apparatus according to any of the preceding claims 16 to 26, wherein the wafer material is a semiconductor, quartz or ceramic material, and the wafer surface has a natural oxide layer or a metal layer.

28. Apparatus according to any one of claims 16 to 27, wherein the plasma etching apparatus is used to etch a native oxide layer or other material such as metal on the surface of a wafer having a diameter of 100 mm or more.

29. The apparatus according to any of the preceding claims 16 to 28, wherein the tray is loaded with a radio frequency power supply 2, the tray being negatively biased.

30. The apparatus of any one of the preceding claims 16 to 29, wherein the radio frequency power supply frequency is in the range of 400KHz to 27 MHz.

Technical Field

The invention relates to the field of integrated circuit production equipment manufacturing, in particular to a method and equipment for wafer plasma etching.

Background

In the field of semiconductor production, before physical vapor deposition, a wafer usually enters a pre-cleaning cavity, the pre-cleaning cavity generates high-density plasma by adopting an inductive coupling plasma method, the wafer is bombarded by the plasma, the surface of the wafer is pre-cleaned, and a natural oxide layer or a material layer such as metal on the surface of the wafer is etched;

when the wafer is subjected to plasma etching, etched materials are splashed from the wafer and deposited on the inner wall of the dielectric window, and once a closed metal layer is deposited on the inner wall of the dielectric window, the coupling of radio frequency energy is influenced. The thickness of the metal conducting layer deposited on the inner wall of the dielectric window is rapidly increased along with the time, so that the problems of difficult plasma starting, unstable plasma, slow etching rate, poor etching uniformity and the like are caused.

In order to avoid the problems, frequent maintenance of the plasma etching chamber is necessary, but the machine downtime is increased, and the productivity is poor;

meanwhile, the uniformity of the existing inductively coupled plasma etching still needs to be improved. In the traditional etching device, due to asymmetric geometric structures of the cavity (such as a wafer transmission valve on one wall of the cavity, an exhaust port on the other side of the cavity and the like), non-uniformity of temperature distribution of elements (such as a heating plate), incomplete symmetry of the elements (such as an induction coil) and the like, the uniformity of etching is poor, and the performance and yield of products are influenced;

the invention is specially designed for the technical problems in the wafer precleaning process.

Disclosure of Invention

The invention provides a method for carrying out plasma etching on a wafer, which comprises the steps of generating inductively coupled plasma in a cavity by using an induction coil through a medium cover, carrying out plasma etching on the wafer on the surface of a heating plate, and removing a natural oxide layer or other substances on the surface of the wafer; the cavity is internally provided with an air inlet ring device, and the inner wall of the air inlet ring is provided with a plurality of air outlets;

the cavity body is internally provided with a shielding structure, and the shielding structure is arranged at the top of the cavity body and close to the medium cover and is used for partially shielding the inner surface of the medium cover, so that an etching object generated in the process of etching metal by using plasma is prevented from splashing and a continuous metal layer is formed on the inner wall of the medium cover;

the gas inlet ring device adopts a circular ring structure, a plurality of gas outlets are formed in the inner wall of the circular ring, and gas inlets are formed in two ends of the outer side of the circular ring, so that the uniformity of process gas distribution is improved, and the uniformity of etching is optimized;

a heating disc device is arranged in the cavity, wherein the wafer tray is placed on the heating disc device;

a wafer rotating device is arranged in the cavity, so that the continuous or discontinuous wafer rotating function is realized, and the etching uniformity is improved;

the upper end of the wafer rotating device is annular, and the wafer rotating device is provided with four supporting points which are distributed in an angle of 90 degrees; a rotary support rod is arranged below the rotary support rod and connected with the soft magnet at the bottom of the cavity, the soft magnet and the permanent magnet are correspondingly placed on the inner side and the outer side of the bottom of the cavity, and the wafer tray is rotated through the rotation of the outer permanent magnet;

the wafer rotating device can also adopt the design of a rotatable top shaft and an up-and-down moving corrugated pipe, or adopt a magnetic fluid rotary sealing mode;

a magnet disc device is arranged in the cavity, can be a permanent magnet or an electromagnet and adopts a continuous rotation mode;

the permanent magnet or the electromagnet device adopts a continuous rotation mode, and an additional magnetic field is formed in the area near the heating plate device by the device, and the magnetic field can generate an electric field and act on positive ions for bombarding the wafer, so that the surface of the wafer can be bombarded by more uniform ions, and the uniformity of plasma etching is improved;

the heating disc device comprises a magnet disc, a heating wire, a corrugated pipe and a motor, wherein the magnet disc and the heating wire are arranged in the heating disc device, and the heating disc device is fixed with the wall of the cavity through the corrugated pipe; the motor is arranged outside the cavity and is connected with the magnet disc through a belt, a gear and a rotating shaft to drive the magnet disc to rotate;

the shielding structure is a metal cage with a hemispherical shape or a shape close to the hemispherical shape;

the shielding structure includes a plurality of notches. The notches are arc-shaped and are uniformly distributed on the surface of the metal cage. The shielding structure can avoid the problems that a continuous metal layer is formed on the inner wall of the dielectric cover, the coupling of radio frequency energy is influenced by the continuous metal layer, and the plasma is unstable and the etching rate is unstable;

the heating disc device can be provided with a heating device, and the controllable temperature range of the heating device is-20 ℃ to 550 ℃;

the wafer material can be semiconductor, quartz or ceramic material, and the surface of the wafer is provided with a natural oxide layer or a metal layer;

the plasma etching is used for etching a natural oxide layer or other substances such as metal on the surface of a wafer, and the diameter of the wafer is 100 mm or more;

the radio frequency power supply 2 is loaded on the tray, negative bias is formed on the tray, so that the kinetic energy of positive ions in the process cavity is increased, the wafers are bombarded, and the plasma etching rate can be improved;

the frequency of the radio frequency power supply is 400KHz to 27 MHz;

in a second aspect of the present invention, there is provided an apparatus for performing plasma etching on a wafer, comprising:

a cavity;

the inductively coupled plasma generating device comprises an induction coil, a radio frequency power supply 1 and a medium cover;

the inner wall of the air inlet ring is provided with a plurality of air outlets;

the shielding structure is arranged at the top of the cavity and close to the medium cover and is used for partially shielding the inner surface of the medium cover and avoiding forming a continuous metal layer on the inner wall of the medium cover;

the gas inlet ring device adopts a circular ring structure, a plurality of gas outlets are formed in the inner wall of the circular ring, and gas inlets are formed in two ends of the outer side of the circular ring, so that the uniformity of process gas distribution is improved, and the uniformity of etching is optimized;

a heating disc device is arranged in the cavity, wherein the wafer tray is placed on the heating disc device;

a wafer rotating device is arranged in the cavity, so that the continuous or discontinuous wafer rotating function is realized, and the etching uniformity is improved;

the upper end of the wafer rotating device is annular, and the wafer rotating device is provided with four supporting points which are distributed in an angle of 90 degrees; a rotary support rod is arranged below the rotary support rod and connected with the soft magnet at the bottom of the cavity, the soft magnet and the permanent magnet are correspondingly placed on the inner side and the outer side of the bottom of the cavity, and the wafer tray is rotated through the rotation of the outer permanent magnet;

the wafer rotating device can also adopt the design of a rotatable top shaft and an up-and-down moving corrugated pipe, or adopt a magnetic fluid rotary sealing mode;

a magnet disc device is arranged in the cavity, can be a permanent magnet or an electromagnet and adopts a continuous rotation mode;

the permanent magnet or the electromagnet device adopts a continuous rotation mode, and an additional magnetic field is formed in the area near the heating plate device by the device, and the magnetic field can generate an electric field and act on positive ions for bombarding the wafer, so that the surface of the wafer can be bombarded by more uniform ions, and the uniformity of plasma etching is improved;

the heating disc device comprises a magnet disc, a heating wire, a corrugated pipe and a motor, wherein the magnet disc and the heating wire are arranged in the heating disc device, and the heating disc device is fixed with the wall of the cavity through the corrugated pipe; the motor is arranged outside the cavity and is connected with the magnet disc through a belt, a gear and a rotating shaft to drive the magnet disc to rotate;

the shielding structure is a metal cage with a hemispherical shape or a shape close to the hemispherical shape;

the shielding structure includes a plurality of notches. The notches are arc-shaped and are uniformly distributed on the surface of the metal cage. The shielding structure can avoid the problems that a continuous metal layer is formed on the inner wall of the dielectric cover, the coupling of radio frequency energy is influenced by the continuous metal layer, and the plasma is unstable and the etching rate is unstable;

the heating disc device can be provided with a heating device, and the controllable temperature range of the heating device is-20 ℃ to 550 ℃.

The wafer material can be semiconductor, quartz or ceramic material, and the surface of the wafer is provided with a natural oxide layer or a metal layer;

the plasma etching is used for etching a natural oxide layer or metal on the surface of a wafer, and the diameter of the wafer is 100 mm or more;

the radio frequency power supply 2 is loaded on the tray, negative bias is formed on the tray, so that the kinetic energy of positive ions in the process cavity is increased, the wafers are bombarded, and the plasma etching rate can be improved;

the frequency of the radio frequency power supply is 400KHz to 27 MHz.

Drawings

FIG. 1 is a schematic view of the overall structure of the patented apparatus of the present invention;

FIG. 2 is a schematic view of the air inlet ring structure of the present invention;

FIG. 3 is a schematic structural view of a heating disc device according to the present invention;

FIG. 4 is a schematic view of a wafer rotation apparatus according to the present invention;

Detailed Description

The invention is further explained below with reference to the figures and examples;

referring to fig. 1, the apparatus for plasma etching a wafer according to the present invention uses an induction coil 101 to generate an inductively coupled plasma in a chamber through a dielectric cover 102, and performs plasma etching on a wafer 108 carried by a tray 106, including a gas inlet ring 105, the tray 106, a heating plate device 107, the wafer 108, a chamber 109, a wafer rotating device 110, and a motor 111. The induction coil 101 and the dielectric cap 102 are mounted over a chamber 109, the wafer 108 is placed on a tray 106, the tray 106 is placed on a heating disk assembly 107, and the heating disk assembly 107 and the wafer rotation assembly 110 are inside the chamber 109. The plasma etching device comprises an induction coil 101, a radio frequency power supply 1 (not shown), a dielectric cover 102 and a shielding structure 103, wherein the induction coil 101 generates inductively coupled plasma in a cavity 109 through the dielectric cover 102 to perform plasma etching on a wafer 108 and remove a natural oxide layer or other substances on the surface of the wafer 108;

as shown in fig. 2, the air inlet ring 105 is circular, a plurality of air outlets are formed in the inner wall of the circular ring, and air inlets are formed at two ends of the outer side of the circular ring;

the shielding structure 103 is disposed at the top of the cavity 109 near the dielectric cover 102, and is used for partially shielding the inner surface of the dielectric cover 102. The shielding structure 103 is a metal cage close to a hemisphere, and comprises a plurality of gaps, wherein each gap is arc-shaped, and the width of each gap is 1mm to 3 mm. The shielding structure 103 may avoid the formation of a continuous metal layer on the inner wall of the dielectric cap 102. The continuous metal layer can influence the coupling of radio frequency energy, so that the problems of unstable plasma and unstable etching rate are caused;

fig. 3 shows that the heating plate device 107 of the present invention includes a magnet plate 302, a heater 301, a corrugated tube, a rf power source 303 and a motor 111, wherein the magnet plate 302 and the heater 301 are installed inside the heating plate device 107, and the heating plate device 107 is placed inside the cavity 109 and fixed to the cavity wall through the corrugated tube. The motor 111 is arranged outside the cavity 109 and is connected with the magnet disc 302 through a belt, a gear 304 and a rotating shaft to drive the magnet disc 302 to rotate;

the magnetic disk 302 of the heating disk device 107 can be a permanent magnet or an electromagnet, or a combination of a permanent magnet and a soft magnet. The magnet disc 302 is continuously rotated in the plasma etching process, and the magnet disc 302 is driven to rotate by the motor 111. The magnetic disk 302 can form a secondary magnetic field in the vicinity of the heating disk device 107, thereby attracting electrons from below the dielectric shield and forming an electric field which acts on the ions, thereby adjusting the direction and energy of positive ion movement in the vicinity of the wafer 108, and by optimizing the distribution of the secondary magnetic field (or electric field), the surface of the wafer 108 can be bombarded by more uniform ions, thereby improving the uniformity of plasma etching on the surface of the wafer 108;

the surface of the heating disc device 107 can be provided with a single or a plurality of areas for respectively controlling the temperature, and the temperature control range is-20 ℃ to 550 ℃;

an external radio frequency power supply 303 is loaded on the tray 106, a negative bias is formed on the tray 106 through capacitive coupling, so that the kinetic energy of positive charge ions in the process cavity 109 is increased and the positive charge ions move towards the direction of the tray 106 to bombard the wafer 108, and thus a natural oxidation layer or other substances on the surface of the wafer 108 are removed;

the wafer 108 is placed on the tray 106, and the tray 106 is placed on the heating disc device 107;

the frequency of the radio frequency power supply 303 is 400KHz to 27 MHz;

fig. 4 shows a wafer rotation apparatus 110 according to the present invention, wherein the wafer rotation apparatus 110 comprises a support 401, a support 402, a bearing 405, a soft magnet 403 and a permanent magnet 404;

the upper end of the bracket 401 is disc-shaped, is provided with four supporting points and is distributed at 90 degrees; the supporting rod 402 is connected with the soft magnet 403, the soft magnet 403 and the permanent magnet 404 are correspondingly arranged on the inner side and the outer side of the bottom of the cavity 109, and the supporting rod 402 is connected with the heating disc device 107 through a bearing 405 so as to be convenient to rotate;

when the wafer rotating device 110 is used, the heating disk device 107 is in a high position during plasma etching, the wafer 108 is etched against the tray 106 on the heating disk device 107, and at the same time, the support rod 402 is separated from the support 401. When the wafer 108 needs to be rotated when the etching process is partially completed, heating disk assembly 107 is lowered, support rod 402 is held in contact with support 401, and wafer 108 is released from heating disk assembly 107 and positioned on support 401. Then, the extraluminal permanent magnet 404 rotates, and the support rod 402, the support 401 and the wafer 108 are driven to rotate by a certain angle through the permanent magnet coupling. After the rotation is completed, the heating disk assembly 107 is raised, the support rods 402 disengage from the support 401, the wafer 108 is returned to the tray 106, and the plasma etching process continues. The wafer rotating device can also adopt the design of a rotatable top shaft and an up-and-down moving corrugated pipe, or adopt a magnetic fluid rotary sealing mode. In the whole process, the magnet disc 302 is continuously rotated in the plasma etching process, and the motor 113 drives the magnet disc 302 to rotate. The plasma etching can be performed in two or more steps, and the wafer 108 can be driven by the wafer rotating device 110 to rotate one or more times between the etching steps;

it will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.