Apparatus and method for use of optical system with a plasma processing system

• US 20050173375A1
• Filed: 03/17/2005
• Published: 08/11/2005
• Est. Priority Date: 09/30/2002
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Mitrovic, Andrej S., Ludviksson, Audunn
• Granted Patent: US 7,591,923 B2
• Time in Patent Office: Days
• US Class Current: 216/60
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32972 Spectral analysis

Abstract

A plasma processing system and method for operating an optical system in conjunction with a plasma processing system are provided. The plasma processing system includes an optical system in communication with a plasma processing chamber of the plasma processing system. The optical system has a window and is constructed and arranged to detect a plasma process condition through the window and a transmission condition of the window. The method includes detecting an optical emission from the plasma processing region and monitoring contamination of a window provided by the optical system.

Claims

1. A plasma processing system comprising:

a chamber having an opening and containing a plasma processing region;

a chuck, constructed and arranged to support a substrate within the chamber in the processing region;

a plasma generator in communication with the chamber, the plasma generator being constructed and arranged to generate a plasma during a plasma process in the plasma processing region; and

an optical system in communication with the chamber through the opening and having a window, the optical system being constructed and arranged to detect a plasma process condition through the window and a transmission condition of the window.

2. The plasma processing system of claim 1, wherein the plasma generator comprises an upper electrode and a lower electrode spaced from the upper electrode, the upper and lower electrodes being constructed and arranged to generate the plasma therebetween when power is supplied thereto.

3. The plasma processing system of claim 1, wherein the plasma generator is an antenna.

4. The plasma processing system of claim 1, wherein the optical system comprises a transmission detector system constructed and arranged to detect the transmission condition.

5. The plasma processing system of claim 4, wherein the optical system has an open area formed in a central portion thereof, the open area being configured to receive the window.

6. The plasma processing system of claim 5, wherein the optical system comprises one or more optical baffles positioned in the open area, the one or more optical baffles being configured to reduce interference between the transmission detector system and the optical emission from the plasma processing region.

7. The plasma processing system of claim 4, wherein the transmission detector system comprises:

a transmission input lens configured to transmit light from a light source through the window; and

a transmission output lens configured to receive the light through the window for detecting the transmission condition, the transmission output lens being capable of communicating the transmission condition to the optical system.

8. The plasma processing system of claim 7, wherein the optical system comprises a shutter positioned between the transmission input lens and the window in optical communication therewith, the shutter being configured to at least partially protect the transmission input lens from contamination.

9. The plasma processing system of claim 7, wherein the light transmitted through the window from the transmission input lens is angled with respect to the optical emission from the plasma processing region.

10. The plasma processing system of claim 7, wherein the light transmitted through the window from the transmission input lens is angled at an angle less than 90°

with respect to the optical emission from the plasma processing region.

11. The plasma processing system of claim 1, wherein the optical emission is light.

12. The plasma processing system of claim 1, further comprising a gate valve positioned between the chamber and the optical system, the gate valve being constructed and arranged to substantially isolate the optical system from the chamber.

13. The plasma processing system of claim 1, wherein the optical system includes a spectrometer.

14. The plasma processing system of claim 1, wherein the optical system comprises a signal collection portion constructed and arranged to detect the plasma process condition.

15. The plasma processing system of claim 1, wherein the window is single ported and accessible to the plasma processing region.

16. The plasma processing system of claim 1, wherein the optical system corrects the plasma process condition based on the transmission condition.

17. The plasma processing system of claim 1, wherein the optical system has at least one additional window capable of receiving an optical emission from the plasma processing region.

18. The plasma processing system of claim 1, wherein the optical system has an open area formed in a central portion thereof, the open area being configured to receive the window.

19. The plasma processing system of claim 18, wherein the optical system comprises a restrictor element disposed between the chamber and the optical system.

20. The plasma processing system of claim 19, wherein the restrictor element is configured to create a higher pressure of purge gas passed through the open area due to reduced flow conductance.

21. The plasma processing system of claim 19, wherein the window is sealingly mounted to an end of the restrictor element.

22. The plasma processing system of claim 1, wherein the optical system comprises a window shutter positioned in an optical path between the window and the plasma processing region, the window shutter being configured to at least reduce contamination of the window.

23. The plasma processing system of claim 1, further comprising a laser configured to emit laser light into the plasma processing region.

24. The plasma processing system of claim 23, wherein the optical system receives laser-excited plasma emissions.

25. The plasma processing system of claim 24, wherein the optical system is positioned transverse to the laser light.

26. The plasma processing system of claim 24, wherein the optical system includes an optical diagnostic system.

27. The plasma processing system of claim 23, further comprising a laser beam dump, external to the plasma processing chamber, configured to collect laser light after the laser light has passed through the plasma processing chamber.

28. An optical system adapted for a plasma processing system having a chamber containing a plasma processing region, the optical system comprising:

a signal collection portion having a window positioned therein and being constructed and arranged to detect a plasma process condition through the window and a transmission condition of the window.

29. The optical system of claim 28, wherein the signal collection portion comprises a transmission detector system constructed and arranged to detect the transmission condition.

30. The optical system of claim 29, wherein the signal collection portion has an open area formed in a central portion thereof, the open area being configured to receive the window.

31. The optical system of claim 29, wherein the signal collection portion comprises one or more optical baffles positioned in the open area, the one or more optical baffles being configured to reduce interference between the transmission detector system and the optical emission from the plasma processing region.

32. The optical system of claim 29, wherein the transmission detector system comprises:

a transmission input lens configured to transmit light from a light source through the window; and

a transmission output lens configured to receive the light through the window for detecting the transmission condition, the transmission output lens being capable of communicating the transmission condition to the signal collection portion.

33. The optical system of claim 32, wherein the signal collection portion comprises a shutter positioned between the transmission input lens and the window in optical communication therewith, the shutter being configured to at least partially protect the transmission input lens from contamination.

34. The optical system of claim 32, wherein the light transmitted through the window from the transmission input lens is angled with respect to the optical emission from the plasma processing region.

35. The plasma processing system of claim 34, wherein the light transmitted through the window from the transmission input lens is angled at an angle less than 90°

with respect to the optical emission from the plasma processing region.

36. The optical system of claim 28, wherein the optical emission is light.

37. The optical system of claim 28, wherein the signal collection portion includes a spectrometer.

38. The optical system of claim 28, wherein the window is single ported and accessible to the plasma processing region.

39. The optical system of claim 28, wherein the signal collection portion corrects the plasma process condition based on the transmission condition.

40. The optical system of claim 28, wherein the signal collection portion includes at least one additional window capable of receiving an optical emission from the plasma processing region.

41. The optical system of claim 28, wherein the signal collection portion has an open area formed in a central portion thereof, the open area being configured to receive the window.

42. The plasma processing system of claim 41, further comprising a mounting portion mounted to the plasma processing region and a restrictor element.

43. The plasma processing system of claim 42, wherein the window is sealingly mounted to an end of the restrictor element.

44. The optical system of claim 42, wherein the restrictor element is configured to create a higher pressure of purge gas passed through the open area due to reduced flow conductance.

45. The optical system of claim 28, wherein the signal collection portion comprises a window shutter positioned in an optical path between the window and the plasma processing region, the window shutter being configured to at least reduce contamination of the window.

46. A method for operating an optical system in conjunction with a plasma processing system having a chamber containing a plasma processing region in which a plasma can be generated during a plasma process, the optical system being optically coupled to the plasma processing region, the method comprising:

optically detecting an optical emission from the plasma processing region through a window provided by the optical system with a transmission detector system; and

monitoring contamination of the window.

47. The method of claim 46, wherein the monitoring includes monitoring contamination of the window in real time.

48. The method of claim 46, wherein the optically detecting of the optical emission comprises:

detecting a reference signal representative of light having a first intensity prior to passing through the window of the optical system; and

detecting a transmission signal representative of light having a second intensity after passing through the window of the optical system.

49. The method of claim 48, further comprising:

dividing the second intensity by the first intensity to provide a light intensity ratio, the light intensity ratio providing a transmission coefficient used for monitoring contamination of the window.

50. The method of claim 49, wherein the transmission coefficient corresponds to a percentage of light transmitted through the window.

51. The method of claim 46, further comprising modifying the optical emission from the plasma processing region based on the light intensity ratio.

52. The method of claim 46, further comprising:

optically detecting an optical emission from the plasma processing region through at least one additional window provided by the optical system; and

monitoring contamination of the at least one additional window.

53. The method of claim 46, further comprising supplying a purge gas to the optical system for purging the optical system.

54. The method of claim 46, further comprising restricting light or gas flow to the window.

55. The method of claim 46, further comprising shuttering the transmission detector system to at least partially protect the transmission detector system from contamination.

56. The method of claim 46, further comprising positioning the transmission detector system at an angle with respect to the optical emission from the plasma processing region.

57. The method of claim 46, further comprising positioning the transmission detector system at an angle less than 90°

with respect to the optical emission from the plasma processing region.

58. The method of claim 46, further comprising shuttering the window to at least partially protect the window from contamination.

59. A method for operating an optical system in conjunction with a plasma processing system having a chamber containing a plasma processing region in which a plasma can be generated during a plasma process, the optical system being optically coupled to the plasma processing region, the method comprising:

optically detecting a laser-excited optical emission from the optical system through a window to the plasma processing region, the window being positioned between the laser and the plasma processing region; and

monitoring contamination of the window.

60. The method of claim 59, further comprising passing laser light through the plasma processing region.

61. The method of claim 59, further comprising collecting the laser light after the laser light has passed through the plasma processing region.

62. The method of claim 59, wherein the monitoring comprises detecting a transmission condition of the window.

63. The method of claim 59, further comprising positioning the optical system transverse to the laser light.