Segmented electrode apparatus and method for plasma processing

• US 20020170676A1
• Filed: 07/08/2002
• Published: 11/21/2002
• Est. Priority Date: 01/10/2000
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Johnson, Wayne, Mitrovic, Andrej S.
• Granted Patent: US 6,863,020 B2
• Time in Patent Office: Days
• US Class Current: 156/345.47
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32532 Electrodes
• CPC Class Codes: H01J 37/32568 Relative arrangement or disposition of electrodes; moving means

Abstract

An electrode assembly (50) and an associated plasma reactor system (10) and related methods for a variety of plasma processing applications. The electrode assembly provides control of a plasma density profile (202) within an interior region (30) of a plasma reactor chamber (20). The electrode assembly includes an upper electrode (54) having a lower surface (54L), an upper surface (54U) and an outer edge (54E). The lower surface of the upper electrode faces interior region of the plasma chamber housing the plasma (200), and thus interfaces with the plasma. The electrode assembly further includes a segmented electrode (60) arranged proximate to and preferably substantially parallel with the upper surface of the upper electrode. The segmented electrode comprises two or more separated electrode segments (62a, 62b, . . . 62n), each having an upper and lower surface. Each electrode segment is spaced apart from the upper electrode upper surface by a corresponding controlled gap (Ga, Gb, . . . Gn). The electrode assembly may further include one or more actuators (110) attached to one or more electrode segments at the upper surface of the one or more electrode segments. The actuators allow for movement of the one or more electrode segments to adjust one or more of the controlled gaps. The adjustable controlled gaps allow for controlling the shape of the plasma density profile within the interior region of the chamber, thereby allowing for a desired plasma process result.

Claims

1. An electrode assembly for providing a controlled RF electric field profile within a region capable of supporting a plasma, comprising:

a) an upper electrode having a lower surface, an upper surface and an outer edge, wherein the region capable of supporting a plasma is adjacent said upper electrode lower surface; and

b) a segmented electrode arranged proximate to said upper electrode upper surface, comprising two or more separated electrode segments each having an upper and lower surface, each of said electrode segments being spaced apart from said upper electrode upper surface by a corresponding controlled gap.

2. An electrode assembly according to claim 1, further including one or more actuators attached to one or more electrode segments at said upper surface of said one or more electrode segments, for moving said one or more electrode segments to adjust one or more of said controlled gaps.

3. An electrode assembly according to claim 2, wherein said actuators are piezoelectric transducers.

4. An electrode assembly according to claim 1, further including first corrugations and first spaces on said lower surfaces of said electrode segments, and second corrugations and second spaces on said upper surface of said upper electrode, wherein said first corrugations are aligned with said second spaces.

5. An electrode assembly according to claim 2, further including first corrugations and first spaces on said lower surfaces of said electrode segments, and second corrugations and second spaces on said upper surface of said upper electrode, wherein said first corrugations are aligned with said second spaces.

6. An electrode according to claim 4 or 5, wherein said second spaces are sized slightly larger than said first corrugations.

7. An electrode assembly according to claim 5, wherein said one or more actuators protrude into corresponding one or more first corrugations.

8. An electrode assembly according to claim 2, further including an actuator controller system electronically connected to said one or more actuators, for controlling said actuators.

9. An electrode assembly according to claim 8, further including one or more segment electrode RF power supply systems electronically connected to said one or more segment electrodes through respective one or more segment electrode RF feeds.

10. An electrode assembly according to claim 9, further including a main RF power supply system electronically connected to said upper electrode through a main RF feed.

11. An electrode assembly according to claim 10, further including an RF control system electronically connected to said upper electrode and one or more segment electrode RF power supply systems.

12. An electrode assembly according to claim 11, further including a main control system electronically connected to said actuator and RF control system.

13. An electrode assembly according to claim 12, further including a pressure sensor in the chamber and a temperature sensor on the segmented electrode assembly, both electronically connected to said main control system.

14. An electrode assembly according to claim 13, further including a database electronically connected to said main control system, containing information pertaining to a plurality of parameter values corresponding to a variety of plasma density profiles.

15. An electrode assembly according to claim 10 wherein said main RF power supply system and said two or more electrode segment RF power supply systems include a signal generator, a gain stage, a phase shifter, a match network, and a bandpass filter.

16. An electrode assembly according to claim 1, 2, 4 or 5, further including an insulator ring surrounding said outer edge of said upper electrode.

17. An electrode assembly according to claim 1, 2, 4 or 5, further including a modular housing enclosing said two or more electrode segments and said outer edge, said modular housing having dielectric side walls, and an upper wall, which in combination with said upper surface of said upper electrode define an electrode cavity containing a dielectric cooling fluid which is circulated around said electrode segments, over said upper surface of said upper electrode, and through said controlled gaps.

18. An electrode assembly according to claim 1, 2, 4 or 5, wherein one or more of said controlled gaps includes a solid dielectric layer.

19. An electrode according to claim 1, wherein one or more of said controlled gaps includes a solid dielectric layer that fills the entirety of said one or more controlled gaps.

20. An electrode assembly according to claim 1, 2, 4 or 5, as arranged in a plasma chamber having sidewalls and an interior region with an insulator ring arranged within the interior region adjacent the sidewalls, the electrode assembly further including a modular housing enclosing said two or more electrode segments and said outer edge and said upper surface of said upper electrode, and also including no more than two vacuum seals, with a first vacuum seal arranged between said insulator and said chamber sidewall, and a second vacuum seal arranged between said insulator and said modular housing.

21. An electrode assembly according to claim 1, 2, 4 or 5, wherein said two or more electrode segments are wedge-shaped and symmetrically arranged in a plane.

22. An electrode assembly according to claim 21, wherein the number of wedge-shaped electrode segments is four.

23. An electrode assembly according to claim 1, 2, 4 or 5, wherein said two or more electrode segments are circular-shaped.

24. An electrode assembly according to claim 1, 2, 4 or 5, wherein said upper electrode includes a gas conduit leading from said upper electrode upper surface to one or more gas injection holes on said upper electrode lower surface.

25. A plasma reactor system comprising:

a) a plasma chamber having a lower wall and sidewalls;

b) a substrate support member having a support surface for supporting a substrate, arranged adjacent said lower wall; and

c) an electrode assembly according to claim 1 or 4, arranged adjacent said substrate support member and within said chamber sidewalls such that said lower surface of said upper electrode and said substrate surface are substantially parallel and form, in combination with said chamber sidewalls, an interior region capable of containing a plasma.

26. A plasma reactor system according to claim 25, further including a cooling system in fluid communication with said electrode assembly, for flowing fluid through said electrode assembly.

27. A plasma reactor system according to claim 26, further including a vacuum system in pneumatic communication with said interior region, for regulating the pressure of said interior region.

28. A plasma reactor system according to claim 27, further including:

a) two or more electrode segment RF power supply systems electronically connected to respective said two or more electrode segments; and

b) a main RF power supply system electronically connected to said upper electrode.

29. A plasma reactor system according to claim 28, wherein said two or more electrode segment RF power supplies systems and said main RF power supply system each include a frequency generator, a gain stage, a phase shifter, a match network, and a bandpass filter.

30. A plasma reactor system according to claim 28, further including a gas supply system in pneumatic communication with said interior region, for supplying gas to said interior region.

31. A plasma reactor system according to claim 30, further including a wafer handling system in operative communication with said plasma chamber, for placing and removing substrates onto and from said substrate support member.

32. A plasma reactor system according to claim 31, further including a main control system electronically connected to said cooling system, said vacuum system, said two or more electrode segment RF power supply systems, said main RF power supply system, said gas supply system and said wafer handling system, for controlling said cooling system, said vacuum system, said two or more electrode segment RF power supply systems, said main RF power supply system, said gas supply system and said wafer handling system through electronic signals generated by said main control system.

33. A plasma reactor system comprising:

a) a plasma chamber having a lower wall and sidewalls;

b) a substrate support member having a support surface for supporting a substrate, arranged adjacent said lower wall; and

c) an electrode assembly according to claim 2 or 5, arranged adjacent said substrate support member and within said chamber sidewalls such that said lower surface of said upper electrode and said substrate surface are substantially parallel and form, in combination with said chamber sidewalls, an interior region capable of containing a plasma.

34. A plasma reactor system according to claim 33, further including a cooling system in fluid communication with said electrode assembly, for flowing fluid through said electrode assembly.

35. A plasma reactor system according to claim 34, further including a vacuum system in pneumatic communication with said interior region, for regulating the pressure of said interior region.

36. A plasma reactor system according to claim 35, further including:

a) two or more electrode segment RF power supply systems electronically connected to respective said two or more electrode segments; and

b) a main RF power supply system electronically connected to said upper electrode.

37. A plasma reactor system according to claim 36, wherein said two or more electrode segment RF power supply systems and said main RF power supply system each include a frequency generator, a gain stage, a phase shifter, a match network, and a bandpass filter.

38. A plasma reactor system according to claim 36, further including a gas supply system in pneumatic communication with said interior region, for supplying gas to said interior region.

39. A plasma reactor system according to claim 38, further including an actuator controller system in operative communication with said one or more actuators.

40. A plasma reactor according to claim 39, wherein said one or more actuators are electronic actuators electrically connected to said actuator controller system.

41. A plasma reactor system according to claim 40, further including a wafer handling system in operative communication with said plasma chamber for placing and removing substrates onto and from said substrate support member.

42. A plasma reactor system according to claim 41, further including a main control system electronically connected to said cooling system, said vacuum system, said two or more electrode segment RF power supply systems, said main RF power supply system, said gas supply system, said actuator controller system and said wafer handling system, for controlling said cooling system, said vacuum system, said two or more electrode segment RF power supply systems, said main RF power supply system, said gas supply system, said actuator controller system and said wafer handling system through electronic signals generated by said main control system.

48. A method of processing a substrate with a plasma having a plasma density profile approaching a desired plasma density profile, comprising the steps of:

a) providing the plasma reactor chamber of claim 25;

b) providing one or more plasma gases into the interior region;

c) providing RF power to the upper electrode and to the two or more electrode segments so as to form the plasma having an associated first plasma density profile in the interior region;

d) measuring said first plasma density profile;

e) adjusting one or more of the two or more electrode segments relative to the upper electrode so as to alter the plasma density profile to form a second plasma density profile that matches or approaches the desired plasma density profile;

f) placing a substrate in the interior region onto the substrate support member; and

g) processing the substrate with said second plasma density profile.

50. A method of processing a substrate with a plasma having a plasma density profile approaching a desired plasma density profile, comprising the steps of:

a) providing the plasma reactor chamber of claim 33;

b) providing one or more plasma gases into the interior region;

c) providing RF power to the upper electrode and to the two or more electrode segments so as to form the plasma having an associated first plasma density profile in the interior region;

d) measuring said first plasma density profile;

e) adjusting one or more of the two or more electrode segments relative to the upper electrode so as to alter the plasma density profile to form a second plasma density profile that matches or approaches the desired plasma density profile;

f) placing a substrate in the interior region onto the substrate support member; and

g) processing the substrate with said second plasma density profile.

51. A method according to claim 50, wherein said measuring of said first plasma density profile in said step d) is accomplished by performing one of blanket plasma etching and blanket plasma deposition of a bare substrate, and measuring the effect on the substrate.

52. An electrode assembly according to claim 15, wherein said segmented electrode is an output capacitor of said match network.

53. A method of plasma processing first and second substrates with first and second plasma density profiles from first and second electrode assemblies, respectively, comprising the steps of:

a) providing the plasma reactor chamber of claim 25, wherein said electrode assembly included therein is a first electrode assembly;

b) processing the first substrate using said plasma reactor chamber having a first plasma density profile associated with said first electrode assembly;

c) replacing said first electrode assembly with a second electrode assembly associated with a second plasma density profile; and

d) processing the second substrate using said plasma reactor chamber and said second plasma density profile.

54. A method according to claim 53, wherein said first plasma density profile and said second plasma density profile differ substantially from one another.

55. A method according to claim 53, wherein said first and second substrate are the same substrate.

56. A method of plasma processing first and second substrates with first and second plasma density profiles from first and second electrode assemblies, respectively, comprising the steps of:

a) providing the plasma reactor chamber of claim 33, wherein said electrode assembly included therein is a first electrode assembly;

b) processing the first substrate using said plasma reactor chamber having a first plasma density profile associated with said first electrode assembly;

c) replacing said first electrode assembly with a second electrode assembly associated with a second plasma density profile; and

d) processing the second substrate using said plasma reactor chamber and said second plasma density profile.

57. A method according to claim 56, wherein said first plasma density profile and said second plasma density profile differ substantially from one another.

58. A method according to claim 56, wherein said first and second substrate are the same substrate.

59. A system according to claim 25, wherein said electrode assembly is a first modular electrode assembly that is removable and capable of being replaced with a second modular electrode assembly.

60. A system according to claim 33, wherein said electrode assembly is a first modular electrode assembly that is removable and capable of being replaced with a second modular electrode assembly.

43. A method of adjusting a plasma density profile of a plasma contained in an interior region of a plasma reactor, so as to cause the plasma density profile to match or approach a desired plasma density profile, the method comprising the steps of:

a) providing, adjacent the interior region, an electrode assembly having an upper electrode with an upper and lower surface, with the upper electrode lower surface facing the interior region, and two or more electrode segments arranged adjacent to the upper electrode upper surface so as to capacitively couple with the upper electrode, said two or more electrode segments being independently movable relative to said upper electrode upper surface;

b) operating the plasma reactor and creating a database containing information relating to a plurality of parameters associated with a plurality of operating conditions corresponding to a plurality of different plasma density profiles;

c) determining the plasma density profile by operating the plasma reactor to expose a substrate to the plasma and measuring the effect of the plasma on the substrate;

d) using the database of said step b), comparing said determined plasma density profile in said step c) to the desired plasma density profile; and

e) altering said determined plasma density profile to approach the desired plasma density profile by moving one or more electrode segments.

44. A method according to claim 43, wherein said step c) of determining a plasma density profile includes etching a substrate with the plasma and measuring the etch properties of the substrate.

45. A method according to claim 43, wherein said step c) of determining a plasma density profile includes plasma depositing a material on a substrate with the plasma and measuring a deposition profile on the substrate.

46. A method according to claim 43, wherein said step b) includes blanket etching a plurality of substrates and measuring the effect of the etch on the substrates.

47. A method according to claim 43, wherein said step b) includes blanket deposition on a plurality of substrates and measuring the effect of the deposition on the substrates.

49. A method according to claim 48, wherein said measuring of said first plasma density profile in said step d) is accomplished by performing one of blanket plasma etching and blanket plasma deposition of a bare substrate, and measuring the effect on the substrate.