Claims
- 1. A plasma generating apparatus comprising:
- a microwave generator for generating microwaves;
- a processing chamber having a plasma-forming region therein;
- a waveguide coupled to the microwave generator and the processing chamber for enabling microwaves to propagate from the microwave generator to the processing chamber, the microwaves propagating in a plurality of propagation modes in at least one portion of the waveguide, the waveguide and the processing chamber constituting a microwave propagating assembly; and
- mode restricting means coupled to the microwave propagating assembly for restricting a number of propagation modes of microwaves arriving at the plasma-forming region to at least one predetermined propagation mode selected from the plurality of propagation modes, the at least one predetermined propagation mode being fewer in number than the plurality of propagation modes;
- wherein microwaves emerge from an outlet of the mode restricting means in a desired propagation state having the at least one predetermined propagation mode and propagate from the outlet of the mode restricting means to at least the plasma-forming region of the processing chamber in the desired propagation state in only the at least one predetermined propagation mode without any change in propagation state and propagation mode occurring.
- 2. A plasma generating apparatus according to claim 1, wherein the outlet of the mode restricting means is disposed in the waveguide.
- 3. A plasma generating apparatus according to claim 1, wherein the outlet of the mode restricting means is disposed in the processing chamber.
- 4. A plasma generating apparatus according to claim 1, wherein a total area of the cross section of the at least one portion of the waveguide is equal to a total area of the cross section of the processing chamber;
- wherein the mode restricting means has at least one microwave propagating portion through which microwaves propagate; and
- wherein a total cross-sectional area of the at least one microwave propagating portion of the mode restricting means is substantially equal to the total area of the cross section of the at least one portion of the waveguide.
- 5. A plasma generating apparatus according to claim 1, wherein the mode restricting means includes at least one divider for dividing the mode restricting means into a plurality of microwave propagating portions; and
- wherein a total cross-sectional area of the microwave propagating portions is greater than a total cross-sectional area of the at least one divider.
- 6. A plasma generating apparatus according to claim 1, wherein the mode restricting means includes at least one divider for dividing the mode restricting means into a plurality of microwave propagating portions; and
- wherein a thickness of each of the at least one divider is sufficiently small to avoid reflection of microwaves from an end of each of the at least one divider.
- 7. A plasma generating apparatus according to claim 1, wherein the mode restricting means includes at least one divider for dividing the mode restricting means into a plurality of microwave propagating portions; and
- wherein a length of each of the at least one divider in a microwave propagating direction is an integral multiple of one-quarter of a wavelength of microwaves propagating in the microwave propagating portions.
- 8. A plasma generating apparatus comprising:
- a microwave generator for generating microwaves having a predetermined frequency;
- a processing chamber having a plasma-forming region therein;
- a waveguide coupled to the microwave generator and the processing chamber for enabling microwaves to propagate from the microwave generator to the processing chamber, at least one portion of the waveguide having a cross section with a dimension which enables microwaves having the predetermined frequency to propagate in N.sub.1 propagation modes, where N.sub.1 .gtoreq.2, the waveguide and the processing chamber constituting a microwave propagating assembly; and
- mode restricting means coupled to the microwave propagating assembly for restricting a number of propagation modes of microwaves having the predetermined frequency arriving at the plasma-forming region to N.sub.2 propagation modes selected from the N.sub.1 propagation modes, where 1.ltoreq.N.sub.2 .ltoreq.N.sub.1 -1;
- wherein the waveguide includes:
- a waveguide section coupled to the microwave generator and having a cross section with a first dimension which enables microwaves having the predetermined frequency to propagate in a single propagation mode; and
- a transitional waveguide section having a first end and a second end, the first end being coupled to the waveguide section and having a cross section with the first dimension, the second end being coupled to the processing chamber and having a cross section with a second dimension which enables microwaves having the predetermined frequency to propagate in the N.sub.1 propagation modes, the second dimension being greater than the first dimension, the transitional waveguide section enabling microwaves to propagate from the waveguide section to the processing chamber while converting microwaves having the predetermined frequency propagating in the single propagation mode at the first end of the transitional waveguide section into microwaves having the predetermined frequency propagating in the N.sub.1 propagation modes at the second end of the transitional waveguide section; and
- wherein the mode restricting means includes:
- a first mode filter disposed in the transitional waveguide section for enabling only microwaves having the predetermined frequency propagating in the N.sub.2 propagation modes to propagate past the first mode filter; and
- a second mode filter disposed in the processing chamber for enabling only microwaves having the predetermined frequency propagating in the N.sub.2 propagation modes to propagate past the second mode filter.
- 9. A plasma generating apparatus according to claim 8, wherein the first mode filter has a cross section with the second dimension;
- wherein the processing chamber has a cross section with a third dimension, the third dimension being greater than the second dimension; and
- wherein the second mode filter has a cross section with the third dimension.
- 10. A plasma generating apparatus according to claim 9, wherein the cross section of the second end of the transitional waveguide section and the cross section of the processing chamber are each a circular cross section.
- 11. A plasma generating apparatus comprising:
- a microwave generator for generating microwaves having a predetermined frequency;
- a processing chamber having a plasma-forming region therein;
- a waveguide coupled to the microwave generator and the processing chamber for enabling microwaves to propagate from the microwave generator to the processing chamber, at least one portion of the waveguide having a cross section with a dimension which enables microwaves having the predetermined frequency to propagate in N.sub.1 propagation modes, where N.sub.1 .gtoreq.2, the waveguide and the processing chamber constituting a microwave propagating assembly; and
- mode restricting means coupled to the microwave propagating assembly for restricting a number of propagation modes of microwaves having the predetermined frequency arriving at the plasma-forming region to N.sub.2 propagation modes selected from the N.sub.1 propagation modes, where 1.ltoreq.N.sub.2 .ltoreq.N.sub.1 -1;
- wherein the waveguide includes:
- a waveguide section coupled to the microwave generator and having a cross section with a first dimension which enables microwaves having the predetermined frequency to propagate in a single propagation mode; and
- a transitional waveguide section having a first end and a second end, the first end being coupled to the waveguide section and having a cross section with the first dimension, the second end being coupled to the processing chamber and having a cross section with a second dimension which enables microwaves having the predetermined frequency to propagate in the N.sub.1 propagation modes, the second dimension being greater than the first dimension, the transitional waveguide section enabling microwaves to propagate from the waveguide section to the processing chamber while converting microwaves having the predetermined frequency propagating in the single propagation mode at the first end of the transitional waveguide section into microwaves having the predetermined frequency propagating in the N.sub.1 propagation modes at the second end of the transitional waveguide section; and
- wherein the mode restricting means includes a mode filter disposed in the transitional waveguide section for enabling only microwaves having the predetermined frequency propagating in the N.sub.2 propagation modes to propagate past the mode filter.
- 12. A plasma generating apparatus according to claim 11, wherein the mode filter has a cross section with the second dimension.
- 13. A plasma generating apparatus according to claim 12, wherein the processing chamber has a cross section with a dimension not greater than the second dimension.
- 14. A plasma generating apparatus according to claim 13, wherein the cross section of the second end of the transitional waveguide section and the cross section of the processing chamber are each a circular cross section.
- 15. A plasma generating apparatus comprising:
- a microwave generator for generating microwaves having a predetermined frequency;
- a processing chamber having a plasma-forming region therein;
- a waveguide coupled to the microwave generator and the processing chamber for enabling microwaves to propagate from the microwave generator to the processing chamber, at least one portion of the waveguide having a cross section with a dimension which enables microwaves having the predetermined frequency to propagate in N.sub.1 propagation modes, where N.sub.1 .ltoreq.2, the waveguide and the processing chamber constituting a microwave propagating assembly; and
- mode restricting means coupled to the microwave propagating assembly for restricting a number of propagation modes of microwaves having the predetermined frequency arriving at the plasma-forming region to N.sub.2 propagation modes selected from the N.sub.1 propagation modes, where 2.ltoreq.N.sub.2 .ltoreq.N.sub.1 -1;
- wherein microwaves emerge from an outlet of the mode restricting means in a desired propagation state having the N.sub.2 propagation modes and propagate from the outlet of the mode restricting means to at least the plasma-forming region of the processing chamber in the desired propagation state in only the N.sub.2 propagation modes without any change in propagation state and propagation mode occurring.
- 16. A plasma generating apparatus according to claim 15, wherein each of the N.sub.2 propagation modes contributes a respective portion of a total amount of microwave energy arriving at the plasma-forming region; and
- wherein the N.sub.2 propagation modes include a selected propagation mode which contributes a greater portion of the total amount of microwave energy arriving at the plasma-forming region than any other one propagation mode of the N.sub.2 propagation modes.
- 17. A plasma generating apparatus according to claim 16, wherein the selected propagation mode is the TE.sub.11 propagation mode.
- 18. A plasma generating apparatus according to claim 16, wherein the selected propagation mode contributes at least 80% of the total amount of microwave energy arriving at the plasma-forming region.
- 19. A plasma generating apparatus according to claim 18, wherein the selected propagation mode is the TE.sub.11 propagation mode.
- 20. A plasma generating apparatus according to claim 18, wherein the selected propagation mode contributes at least 90% of the total amount of microwave energy arriving at the plasma-forming region.
- 21. A plasma generating apparatus according to claim 20, wherein the selected propagation mode is the TE.sub.11 propagation mode.
- 22. A plasma generating apparatus according to claim 15, wherein a total area of the cross section of the at least one portion of the waveguide is equal to a total area of the cross section of the processing chamber;
- wherein the mode restricting means has at least one microwave propagating portion through which microwaves propagate; and
- wherein a total cross-sectional area of the at least one microwave propagating portion of the mode restricting means is substantially equal to the total area of the cross section of the at least one portion of the waveguide.
- 23. A plasma generating apparatus according to claim 15, wherein the mode restricting means includes at least one divider for dividing the mode restricting means into a plurality of microwave propagating portions; and
- wherein a total cross-sectional area of the microwave propagating portions is greater than a total cross-sectional area of the at least one divider.
- 24. A plasma generating apparatus according to claim 15, wherein the mode restricting means includes at least one divider for dividing the mode restricting means into a plurality of microwave propagating portions; and
- wherein a thickness of each of the at least one divider is sufficiently small to avoid reflection of microwaves from an end of each of the at least one divider.
- 25. A plasma generating apparatus according to claim 15, wherein the mode restricting means includes at least one divider for dividing the mode restricting means into a plurality of microwave propagating portions; and
- wherein a length of each of the at least one divider in a microwave propagating direction is an integral multiple of one-quarter of a wavelength of microwaves propagating in the microwave propagating portions.
- 26. A plasma generating apparatus comprising:
- a microwave generator for generating microwaves having a predetermined frequency;
- a processing chamber having a plasma-forming region therein;
- a waveguide coupled to the microwave generator and the processing chamber for enabling microwaves to propagate from the microwave generator to the processing chamber, at least one portion of the waveguide having a cross section with a dimension which enables microwaves having the predetermined frequency to propagate in N.sub.1 propagation modes, where N.sub.1 .gtoreq.2, the waveguide and the processing chamber constituting a microwave propagating assembly; and
- mode restricting means coupled to the microwave propagating assembly for restricting a number of propagation modes of microwaves having the predetermined frequency arriving at the plasma-forming region to N.sub.2 propagation modes selected from the N.sub.1 propagation modes, where 1.ltoreq.N.sub.2 .ltoreq.N.sub.1 -1;
- wherein the dimension of the cross section of the at least one portion of the waveguide is equal to a dimension of a cross section of the processing chamber.
- 27. A plasma generating apparatus according to claim 26, wherein microwaves emerge from an outlet of the mode restricting means in a desired propagation state having the N.sub.2 propagation modes and propagate from the outlet of the mode restricting means to at least the plasma-forming region of the processing chamber in the desired propagation state in only the N.sub.2 propagation modes without any change in propagation state and propagation mode occurring.
- 28. A plasma generating apparatus according to claim 27, wherein the outlet of the mode restricting means is disposed in the waveguide.
- 29. A plasma generating apparatus according to claim 27, wherein the outlet of the mode restricting means is disposed in the processing chamber.
- 30. A plasma generating apparatus according to claim 26, wherein the N.sub.2 propagation modes are predetermined propagation modes selected from the N.sub.1 propagation modes.
- 31. A plasma generating apparatus according to claim 26, wherein N.sub.2 =1, such that the N.sub.2 propagation modes consist of a single propagation mode.
- 32. A plasma generating apparatus according to claim 31, wherein the single propagation mode is the TE.sub.11 propagation mode.
- 33. A plasma generating apparatus according to claim 26, wherein the N.sub.2 propagation modes are selected from the group consisting of the TE.sub.01, TE.sub.10, TE.sub.11, TM.sub.01, TM.sub.10, and TM.sub.11 propagation modes.
- 34. A plasma generating apparatus according to claim 33, wherein N.sub.2 =1, such that the N.sub.2 propagation modes consist of a single propagation mode selected from the group consisting of the TE.sub.01, TE.sub.10, TE.sub.11, TM.sub.01, TM.sub.10, and TM.sub.11 propagation modes.
- 35. A plasma generating apparatus according to claim 34, wherein the single propagation mode is the TE.sub.11 propagation mode.
- 36. A plasma generating apparatus according to claim 26, wherein the waveguide includes:
- a first waveguide section coupled to the microwave generator and having a cross section with a first dimension which enables microwaves having the predetermined frequency to propagate in a single propagation mode;
- a second waveguide section coupled to the processing chamber and having a cross section with a second dimension which enables microwaves having the predetermined frequency to propagate in the N.sub.1 propagation modes, the second dimension being greater than the first dimension; and
- a transitional waveguide section coupled to the first waveguide section and the second waveguide section for enabling microwaves to propagate from the first waveguide section to the second waveguide section while converting microwaves having the predetermined frequency propagating in the single propagation mode in the first waveguide section into microwaves having the predetermined frequency propagating in the N.sub.1 propagation modes in the second waveguide section.
- 37. A plasma generating apparatus according to claim 36, wherein the transitional waveguide section has a first end and a second end, the first end being coupled to the first waveguide section and having a cross section with the first dimension, the second end being coupled to the second waveguide section and having a cross section with the second dimension.
- 38. A plasma generating apparatus according to claim 36, wherein the mode restricting means includes a mode filter disposed in the second waveguide section for enabling only microwaves having the predetermined frequency propagating in the N.sub.2 propagation modes to propagate past the mode filter.
- 39. A plasma generating apparatus according to claim 38, wherein the mode filter has a cross section with the second dimension.
- 40. A plasma generating apparatus according to claim 39, wherein the processing chamber has a cross section with a dimension not greater than the second dimension.
- 41. A plasma generating apparatus according to claim 40, wherein the cross section of the second waveguide section and the cross section of the processing chamber are each a circular cross section.
- 42. A plasma generating apparatus according to claim 26, wherein a total area of the cross section of the at least one portion of the waveguide is equal to a total area of the cross section of the processing chamber;
- wherein the mode restricting means has at least one microwave propagating portion through which microwaves propagate; and
- wherein a total cross-sectional area of the at least one microwave propagating portion of the mode restricting means is substantially equal to the total area of the cross section of the at least one portion of the waveguide.
- 43. A plasma generating apparatus according to claim 26, wherein the mode restricting means includes at least one divider for dividing the mode restricting means into a plurality of microwave propagating portions; and
- wherein a total cross-sectional area of the microwave propagating portions is greater than a total cross-sectional area of the at least one divider.
- 44. A plasma generating apparatus according to claim 26, wherein the mode restricting means includes at least one divider for dividing the mode restricting means into a plurality of microwave propagating portions; and
- wherein a thickness of each of the at least one divider is sufficiently small to avoid reflection of microwaves from an end of each of the at least one divider.
- 45. A plasma generating apparatus according to claim 26, wherein the mode restricting means includes at least one divider for dividing the mode restricting means into a plurality of microwave propagating portions; and
- wherein a length of each of the at least one divider in a microwave propagating direction is an integral multiple of one-quarter of a wavelength of microwaves propagating in the microwave propagating portions.
- 46. A plasma generating apparatus comprising:
- a microwave generator for generating microwaves having a predetermined frequency;
- a processing chamber having a plasma-forming region therein;
- a waveguide coupled to the microwave generator and the processing chamber for enabling microwaves to propagate from the microwave generator to the processing chamber, at least one portion of the waveguide having a cross section with a dimension which enables microwaves having the predetermined frequency to propagate in N.sub.1 propagation modes, where N.sub.1 .gtoreq.2,the waveguide and the processing chamber constituting a microwave propagating assembly; and
- mode restricting means coupled to the microwave propagating assembly for restricting a number of propagation modes of microwaves having the predetermined frequency arriving at the plasma-forming region to N.sub.2 propagation modes selected from the N.sub.1 propagation modes, where 1.ltoreq.N.sub.2 .ltoreq.N.sub.1 -1;
- wherein the dimension of the cross section of the at least one portion of the waveguide is equal to a dimension of a cross section of the processing chamber; and
- wherein microwaves having the N.sub.2 propagation modes propagate through the mode restricting means.
Priority Claims (2)
Number |
Date |
Country |
Kind |
4-14729 |
Jan 1992 |
JPX |
|
4-191878 |
Jul 1992 |
JPX |
|
CROSS-REFERENCE TO RELATED APPLICATION
This is a continuation of application Ser. No. 08/010,051 filed on Jan. 28, 1993, now U.S. Pat. No. 5,433,789.
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Continuations (1)
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Number |
Date |
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Parent |
10051 |
Jan 1993 |
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