Window for microwave plasma processing device

• US 5,234,526 A
• Filed: 05/24/1991
• Issued: 08/10/1993
• Est. Priority Date: 05/24/1991
• Status: Expired due to Term

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Inoue, Takashi, Tanaka, Masahiko, Pirkle, David, Chen, Ching-Hwa, Miyahara, Shunji
• Primary Examiner(s): Hearn, Brian E.
• Assistant Examiner(s): BASKIN, JONATHAN
• Application Number:
  US07/705,523
• Time in Patent Office: 809 Days
• Field of Search: 118/723, 156/345, 333/252, 333/99 PL, 315/111.21, 315/111.41
• US Class Current: 156/345.42
• CPC Class Codes: H01J 37/32192 Microwave generated discharge H01J37/32357, H01J37/32366, H01J37/32394, H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32238 Windows

Abstract

A microwave transmitting window for a plasma processing device. The window is a body of one or more pieces of the same or different dielectric materials. A surface of the window facing a microwave transmitting horn or waveguide is planar and extends perpendicularly to an axial direction. An opposite surface of the window is recessed such that the body has a non-uniform thickness between the two surfaces. The recessed surface can have various shapes and the overall size of the window can be equal to the size of a plasma formation chamber of the plasma processing device. The outlet of the plasma formation chamber can be formed in an end wall or the outlet can be formed by the inner periphery of the plasma formation chamber.

Claims

1. A microwave plasma processing device including a plasma generation chamber which generates plasma by exciting electron cyclotron resonance using microwaves introduced through a microwave lead-in opening in an end wall of the plasma formation chamber, the microwave lead-in opening having a cross section smaller than a cross section of the plasma formation chamber, the microwave plasma processing device including a microwave-penetrable substance on a side of the plasma generation chamber facing the microwave lead-in opening, the microwave-penetrable substance extending over an entire cross-section of the chamber, the microwave-penetrable substance having a thickness between a surface thereof facing an interior of the plasma generation chamber and another surface opposite thereto, the thickness becoming greater in a direction from a center of the plasma generation chamber to a periphery thereof.

2. A microwave plasma processing device including a plasma generation chamber which generates plasma by exciting electron cyclotron resonance using microwaves introduced through a microwave lead-in opening, the microwave plasma processing device including a first microwave-penetrable substance supported in the microwave lead-in opening with one side of the first microwave-penetrable substance being uniplanar with an inner surface of the plasma generation chamber, and a second microwave-penetrable substance being supported on a side of the plasma generation chamber facing the microwave lead-in opening, the second microwave-penetrable substance extending over an entire cross-section of the chamber, the second microwave-penetrable substance having a thickness between a surface thereof facing an interior of the plasma generation chamber and another surface opposite thereto, the thickness becoming greater in a direction from a center of the plasma generation chamber to a periphery thereof.

3. A microwave transmitting window, comprising:

a solid body of dielectric material, the body including first and second surfaces spaced apart in an axial direction, the body including an outer periphery extending between the first and second surfaces, the first surface being planar and extending perpendicularly to the axial direction, the second surface being recessed such that the body has a non-uniform thickness between the first and second surfaces, the thickness increasing in a direction towards the outer periphery of the body.

4. The microwave transmitting window of claim 3, wherein the first surface is a continuous, uninterrupted surface extending inwardly from the outer periphery, the second surface is a continuous, uninterrupted surface extending inwardly from the outer periphery, the outer periphery is a continuous, uninterrupted surface extending axially from the first surface to the second surface, and the outer periphery has a uniform width in a transverse direction perpendicular to the axial direction.

5. The microwave transmitting window of claim 3, wherein the body is cylindrical or rectangular in axial cross-section.

6. The microwave transmitting window of claim 3, wherein the recessed surface is conical or spherical or parabolic or hyperbolic with respect to the axial direction.

7. The microwave transmitting window of claim 3, wherein the recessed surface includes a conical central portion and a frusto-conical outer portion.

8. The microwave transmitting window of claim 7, wherein the frusto-conical outer portion is tapered with respect to the axial direction to a lesser extent than the conical central portion.

9. The microwave transmitting window of claim 3, wherein the recessed surface extends radially inwardly from the outer periphery of the body, or the second surface includes an outer planar portion extending perpendicularly to the axial direction and the recessed surface extends radially inwardly from the outer planar portion.

10. The microwave transmitting window of claim 9, further comprising a metal shield covering a central portion of the recessed surface.

11. The microwave transmitting window of claim 3, wherein the recessed surface is frusto-conical, the second surface including a planar outer portion and a extending from the central portion to the outer portion.

12. The microwave transmitting window of claim 3, wherein the recessed surface is pyramidal in shape and formed by four triangular surfaces.

13. The microwave transmitting window of claim 3, wherein the recessed surface includes a pyramidal central portion formed by four triangular surfaces and a truncated outer portion formed by four trapezoidal surfaces.

14. The microwave transmitting window of claim 13, wherein the truncated outer portion is tapered with respect to the axial direction to a lesser extent than the pyramidal central portion.

15. The microwave transmitting window of claim 3, further comprising a metal shield covering a central portion of the recessed surface.

16. The microwave transmitting window of claim 3, further including a flange extending radially outwardly from the outer periphery of the body.

17. The microwave transmitting window of claim 16, Wherein the flange is adjacent the first surface of the body.

18. The microwave transmitting window of claim 3, wherein the body comprises at least two discrete parts.

19. The microwave transmitting window of claim 3, further comprising a member of dielectric material, the member including a planar surface abutting the planar surface of the body.

20. The microwave transmitting window of claim 19, wherein the member has an outer periphery spaced radially inwardly of the outer periphery of the body.

21. A plasma generating device, comprising:

a plasma formation chamber having first and second ends thereof spaced apart in an axial direction, a first opening in the first end for passing microwave energy into the plasma formation chamber and a second opening in the second end for passing plasma outwardly of the plasma formation chamber;

a reaction chamber adjacent the second end of the plasma formation chamber, the reaction chamber including a substrate support aligned in the axial direction with the second opening; and

a microwave transmitting window sealing the first opening, the window comprising a body of dielectric material, the body including first and second surfaces spaced apart in the axial direction, the body including an outer periphery extending between the first and second surfaces, the first surface being planar and extending perpendicularly to the axial direction, and the second surface being recessed such that the body has a non-uniform thickness between the first and second surfaces, the thickness increasing in a direction towards the outer periphery of the body.

22. The plasma generating device of claim 21, wherein the plasma formation chamber is formed by at least one wall which extends parallel to the axial direction and the second opening is formed by one axial end of the at least one wall, the second opening having a cross section equal to a cross section of the plasma formation chamber.

23. The plasma generating device of claim 22, wherein the plasma formation chamber is cylindrical in axial cross-section and the at least one wall comprises a cylindrical wall, the device further including a liner of dielectric material completely covering an inner periphery of the cylindrical wall.

24. The plasma generating device of claim 21, wherein the first surface is a continuous, uninterrupted surface extending inwardly from the outer periphery, the second surface is a continuous, uninterrupted surface extending inwardly from the outer periphery, the outer periphery is a continuous, uninterrupted surface extending axially from the first surface to the second surface, and the outer periphery has a uniform width in a transverse direction perpendicular to the axial direction.

25. The plasma generating device of claim 21, wherein the body is cylindrical or rectangular in cross-section.

26. The plasma generating device of claim 21, wherein the recessed surface is conical or spherical or parabolic or hyperbolic with respect to the axial direction.

27. The plasma generating device of claim 21, wherein the recessed surface includes a conical central portion and a frusto-conical outer portion.

28. The plasma generating device of claim 21, wherein the recessed surface extends radially inwardly from the outer periphery of the body or the second surface includes an outer planar portion extending perpendicularly to the axial direction and the recessed surface extends radially inwardly from the outer planar portion.

29. The plasma generating device of claim 21, wherein the recessed surface is frusto-conical, the second surface including a planar outer portion and a planar central portion, the frusto-conical surface extending from the central portion to the outer portion.

30. The plasma generating device of claim 21, wherein the recessed surface is pyramidal in shape and formed by four triangular surfaces.

31. The plasma generating device of claim 21, wherein the recessed surface includes a pyramidal central portion formed by four triangular surfaces and a truncated outer portion formed by four trapezoidal surfaces.

32. The plasma generating device of claim 21, further comprising a metal shield covering a central portion of the recessed surface.

33. The plasma generating device of claim 21, further including a flange extending outwardly from the outer periphery of the body and at least one O-ring cooperating with the flange to seal the plasma formation chamber.

34. The plasma generating device of claim 21, further comprising a microwave guide and a microwave transmitting horn extending between the microwave guide and the window.

35. The plasma generating device of claim 34, wherein the horn has a larger opening at an end thereof facing the window than at an end thereof facing the waveguide, the larger opening being equal in size to a size of the plasma formation chamber.

36. The plasma generating device of claim 21, wherein the body comprises at least two discrete parts.

37. The plasma generating device of claim 21, further comprising a member of dielectric material, the member including a planar surface abutting the planar surface of the body, the member having an outer periphery spaced radially inwardly of the outer periphery of the body.