Radio Frequency Power Control System

• US 20100194195A1
• Filed: 02/05/2009
• Published: 08/05/2010
• Est. Priority Date: 02/05/2009
• Status: Active Grant

• Current Assignee: MKS Instruments Incorporated
• Original Assignee: MKS Instruments Incorporated
• Inventors: Eyerman, Paul, Coumou, David J., Radomski, Aaron, Fisk, Larry J. II, Ioriatti, Carl, Pham, Richard, Stenglein, William
• Granted Patent: US 8,040,068 B2
• Time in Patent Office: Days
• US Class Current: 307/24
• 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 37/32165 Plural frequencies
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H01J 37/3299 Feedback systems
• CPC Class Codes: H03H 7/38 Impedance-matching networks
• CPC Class Codes: H05H 1/46 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/26 takes precedence

Abstract

A radio frequency (RF) system includes a control module that allocates M predetermined frequency intervals. The system also includes N RF sources that each applies first RF power to electrodes within a plasma chamber at frequencies within an assigned respective one of the M predetermined frequency intervals. The N RF sources also each respond to second RF power including feedback from the plasma chamber. The N RF sources each include a processing module that adjusts the first RF power based on the second RF power and the respective one of the M predetermined frequency intervals. M and N are integers greater than 1.

Claims

1. A radio frequency (RF) system comprising:

a control module that allocates M predetermined frequency intervals; and

N RF sources each applying first RF power to electrodes within a plasma chamber at frequencies within an assigned respective one of the M predetermined frequency intervals, and that each respond to second RF power including feedback from the plasma chamber,

wherein the N RF sources each include a processing module that adjusts the first RF power based on the second RF power and the respective one of the M predetermined frequency intervals, wherein M and N are integers greater than 1.

2. The RF system of claim 1, wherein L of the M predetermined frequency intervals overlap, and wherein L is an integer greater than 1.

3. The RF system of claim 2, wherein the control module assigns members of the L of the M predetermined frequency intervals to members of the N RF sources that communicate with non-neighboring ones of the electrodes.

4. The RF system of claim 1, wherein J of the M predetermined frequency intervals correspond to a same predetermined frequency interval, and wherein J is an integer greater than or equal to 1.

5. The RF system of claim 1, wherein the M predetermined frequency intervals are each a matching length, wherein the M predetermined frequency intervals do not overlap, and wherein M=N.

6. The RF system of claim 1, wherein O of the M predetermined frequency intervals are each a matching length and P of the M predetermined frequency intervals are each different lengths, wherein O and P are integers greater than or equal to 1.

7. The RF system of claim 1, wherein each of the N RF sources includes a narrow band filter that filters interference components of the first RF power and the second RF power before the first RF power and the second RF power are processed in the processing module.

8. The RF system of claim 1, further comprising N matching networks that communicate with the N RF sources, respectively.

9. The RF system of claim 1, further comprising:

the plasma chamber; and

N matching networks interposed between the N RF sources and the plasma chamber that match impedances between the N RF sources and the plasma chamber based on signals from the processing modules for each of the N RF sources that control a set point for elements of the N matching networks.

10. The RF system of claim 9, further comprising N sensors positioned between the N matching networks and the plasma chamber that sense the second RF power from the plasma chamber.

11. The RF system of claim 10, wherein the control module further comprises a phase module that selectively provides phases for the frequencies for one or more of the RF sources based on signals from the N sensors.

12. The RF system of claim 1, wherein processing modules for each of the N RF sources include modulation modules that modulate frequencies for RF power output by respective ones of the N RF sources based on at least one of a pseudorandom modulation scheme and a complex frequency modulation scheme.

13. The RF system of claim 12, wherein the modulation modules modulate the frequencies using at least one of frequency-shift keying (FSK), phase-shift keying (PSK), quadrature phase-shift keying (QPSK), frequency hopping and fast frequency sweeping.

14. The RF system of claim 1, wherein the control module synchronizes RF power output pulses of members of the N RF sources that share one of the M predetermined frequency intervals.

15. A radio frequency (RF) system comprising:

a control module that allocates M predetermined frequency intervals;

a first tunable RF source that maintains a first set point for delivered load power at a first frequency based on first power delivered to a first electrode in a load, first feedback reflected from the load, and an assigned first of the M predetermined frequency intervals; and

a second tunable RF source that maintains a second set point for delivered load power at a second frequency based on second power delivered to a second electrode in the load, second feedback reflected from the load, and an assigned second of the M predetermined frequency intervals,

wherein M is an integer greater than 1.

16. The RF system of claim 15, wherein the first and second of the M predetermined frequency intervals overlap, and wherein the first electrode does not neighbor the second electrode within the load.

17. The RF system of claim 15, wherein the M predetermined frequency intervals are each a matching length, wherein the M predetermined frequency intervals do not overlap, and wherein M=N.

18. The RF system of claim 15, a third tunable RF source that maintains a third set point for delivered load power at a third frequency based on third power delivered to a third electrode in the load, third feedback reflected from the load, and a third of the M predetermined frequency intervals.

19. The RF system of claim 18, wherein the first and third of the M predetermined frequency intervals correspond to a matching predetermined frequency interval, and the first and second of the M predetermined frequency intervals correspond to different intervals, and wherein the first and third electrodes are non-neighboring electrodes, and wherein the first electrode neighbors the second electrode within the load.

20. The RF system of claim 15, wherein O of the M predetermined frequency intervals are each a matching length and P of the M predetermined frequency intervals are each different lengths, wherein O and P are integers greater than or equal to 1.

21. The RF system of claim 15, wherein the first tunable RF source includes a narrow band filter that filters interference components within the first feedback reflected from the load caused by the second power from the second tunable RF source.

22. The RF system of claim 15, further comprising a first matching network that communicates with the first tunable RF source and the load, and a second matching network that communicates with the second tunable RF source and the load.

23. The RF system of claim 15, wherein the first matching network matches impedances between the first tunable RF source and the load based on signals from the first tunable RF source that control a set point for elements of the first matching network.

24. The RF system of claim 23, further comprising a sensor positioned between the first matching network and the load that senses the first and second RF power, wherein the control module further comprises a phase module that selectively provides phases for the frequencies for one or more of the first and second tunable RF sources based on signals from the sensor.

25. The RF system of claim 15, wherein the first tunable RF source includes a modulation module that modulates frequencies for RF power output from the first tunable RF source based on at least one of a pseudorandom modulation scheme and a complex frequency modulation scheme.

26. The RF system of claim 25, wherein the modulation module modulates the frequencies using at least one of frequency-shift keying (FSK), phase-shift keying (PSK), quadrature phase-shift keying (QPSK), frequency hopping and fast frequency sweeping.

27. The RF system of claim 25, wherein the control module synchronizes RF power output pulses for the first tunable RF source and the second tunable RF source when the first tunable RF source shares one of the M predetermined frequency intervals with the second tunable RF source.

28. The RF system of claim 15, further comprising the load, wherein the load includes a plasma chamber.

29. A method for operating a radio frequency (RF) system comprising:

allocating M predetermined frequency intervals;

applying N first RF power outputs to electrodes within a plasma chamber each at frequencies within an assigned respective one of the M predetermined frequency intervals;

receiving feedback from the plasma chamber; and

adjusting the N first RF power outputs based on the feedback and the respective one of the M predetermined frequency intervals, wherein M and N are integers greater than 1.

30. The method of claim 29, wherein L of the M predetermined frequency intervals overlap, and wherein L is an integer greater than 1.

31. The method of claim 30, further comprising assigning members of the L of the M predetermined frequency intervals to members of the N first RF power outputs that communicate with non-neighboring ones of the electrodes.

32. The method of claim 29, wherein J of the M predetermined frequency intervals correspond to the same predetermined frequency interval, and wherein J is an integer greater than or equal to 1.

33. The method of claim 29, wherein the M predetermined frequency intervals are each a matching length, wherein the M predetermined frequency intervals do not overlap, and wherein M=N.

34. The method of claim 29, wherein O of the M predetermined frequency intervals are each a matching length and P of the M predetermined frequency intervals are each different lengths, wherein O and P are integers greater than or equal to 1.

35. The method of claim 29, further comprising selectively providing phases for the frequencies for one or more RF sources for the N RF power outputs.

36. The method of claim 29, further comprising modulating frequencies for members of the N RF power outputs based on at least one of a pseudorandom modulation scheme and a complex frequency modulation scheme.

37. The method of claim 29, further comprising synchronizing pulses for members of the N RF power outputs that share one of the M predetermined frequency intervals.

38. A method for operating a radio frequency (RF) system comprising:

allocating M predetermined frequency intervals;

actively maintaining a first set point for delivered load power at a first frequency based on first power delivered to a first electrode in a load, first feedback from the load, and an assigned first of the M predetermined frequency intervals; and

actively maintaining a second set point for delivered load power at a second frequency based on second power delivered to a second electrode in the load, second feedback from the load, and an assigned second of the M predetermined frequency intervals,

wherein M is an integer greater than 1.

39. The method of claim 38, wherein the first and second of the M predetermined frequency intervals overlap, and wherein the first electrode does not neighbor the second electrode within the load.

40. The method of claim 38, wherein the M predetermined frequency intervals are each a matching length, wherein the M predetermined frequency intervals do not overlap, and wherein M=N.

41. The method of claim 38, further comprising actively maintaining a third set point for delivered load power at a third frequency based on third power delivered to a third electrode in the load, third feedback from the load, and a third of the M predetermined frequency intervals.

42. The method of claim 41, wherein the first and third of the M predetermined frequency intervals correspond to the same predetermined frequency interval and the first and second of the M predetermined frequency intervals correspond to different intervals, and wherein the first and third electrodes are non-neighboring electrodes, and wherein the first electrode neighbors the second electrode within the load.

43. The method of claim 38, wherein O of the M predetermined frequency intervals are each a matching length and P of the M predetermined frequency intervals are each different lengths, wherein O and P are integers greater than or equal to 1.

44. The method of claim 38, further comprising selectively providing phases for the first and second frequencies.

45. The method of claim 38, further comprising modulating the first and second frequencies based on at least one of a pseudorandom modulation scheme and a complex frequency modulation scheme.

46. The method of claim 38, further comprising synchronizing pulses for the first power and the second power.