Method and apparatus for monitoring plasma processing operations

• US 6,157,447 A
• Filed: 04/23/1998
• Issued: 12/05/2000
• Est. Priority Date: 04/23/1998
• Status: Expired due to Fees

• Current Assignee: Sandia Corporation (Martin Marietta Corporation)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Ward, Pamela Peardon Denise, Smith, Michael Lane Jr., Stevenson, Joel O'Don
• Primary Examiner(s): Kim, Robert H.
• Assistant Examiner(s): LAUCHMAN, LAYLA G
• Application Number:
  US09/065,359
• Time in Patent Office: 957 Days
• Field of Search: 356/311, 356/316, 356/72, 438/9, 204/192.33, 156/345, 702/32
• US Class Current: 356/316
• CPC Class Codes: G01J 2003/2866 Markers; Calibrating of scan
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/443 Emission spectrometry

Abstract

The invention generally relates to various aspects of a plasma process, and more specifically the monitoring of such plasma processes. One aspect relates in at least some manner to calibrating or initializing a plasma monitoring assembly. This type of calibration may be used to address wavelength shifts, intensity shifts, or both associated with optical emissions data obtained on a plasma process. A calibration light may be directed at a window through which optical emissions data is being obtained to determine the effect, if any, that the inner surface of the window is having on the optical emissions data being obtained therethrough, the operation of the optical emissions data gathering device, or both. Another aspect relates in at least some manner to various types of evaluations which may be undertaken of a plasma process which was run, and more typically one which is currently being run, within the processing chamber. Plasma health evaluations and process identification through optical emissions analysis are included in this aspect. Yet another aspect associated with the present invention relates in at least some manner to the endpoint of a plasma process (e.g., plasma recipe, plasma clean, conditioning wafer operation) or discrete/discernible portion thereof (e.g., a plasma step of a multiple step plasma recipe). A final aspect associated with the present invention relates to how one or more of the above-noted aspects may be implemented into a semiconductor fabrication facility, such as the distribution of wafers to a wafer production system.

Claims

1. A method for monitoring a plasma process comprising the steps of:

loading a quantity of product into a processing chamber;

conducting a plasma process on said product in said processing chamber, said processing chamber comprising a window;

obtaining data on said plasma process through said window, wherein said obtaining step is executed at least a plurality of times during said conducting step;

monitoring a condition of said window other than through said obtaining step; and

evaluating said conducting step using both said obtaining step and said monitoring step.

2. A method, as claimed in claim 1, wherein:

said loading step comprises loading at least one wafer into said processing chamber.

3. A method, as claimed in claim 1, wherein:

said obtaining step comprises obtaining optical emissions of plasma in said processing chamber during said conducting step.

4. A method, as claimed in claim 1, wherein:

said monitoring step is terminated during execution of said conducting step.

5. A method, as claimed in claim 1, wherein:

said monitoring step is executed only at one of first and second times, said first time being before execution of said conducting step and said second time being after said execution of said conducting step.

6. A method, as claimed in claim 1, wherein:

said monitoring step comprises assessing first data which is independent of any data relating to plasma in said processing chamber during said conducting step.

7. A method, as claimed in claim 1, wherein said window comprises an inner surface which is exposed to said conducting step and an outer surface which is isolated from said conducting step, and wherein said monitoring step comprises:

directing a calibration light toward said window from a location which is exterior of said processing chamber;

reflecting a first portion of said calibration light from said inner surface said window; and

comparing said calibration light from said directing step with said first portion of said calibration light from said reflecting step.

8. A method, as claimed in claim 7, wherein:

said comparing step comprises comparing a spectral pattern of said calibration light from said directing step with a spectral pattern of said first portion of said calibration light from said reflecting step.

9. A method, as claimed in claim 8, wherein said spectral pattern of said calibration light from said directing step is within a first range including at least wavelengths of about 200 nanometers to about 1,000 nanometers, wherein said spectral pattern of said first portion of said calibration light from said reflecting step is at least within said first range, and wherein:

said comparing step comprises comparing an intensity of said spectral pattern of said calibration light from said directing step with an intensity of said spectral pattern of said first portion of said calibration light from said reflecting step using a wavelength resolution of no more than about 1 nanometer, wherein said wavelength resolution means that a wavelength spacing between each adjacent pair of wavelengths compared throughout said first range is no more than about 1 nanometer.

10. A method, as claimed in claim 7, wherein:

said comparing step comprises noting any differences between said calibration light from said directing step and said first portion of said calibration light from said reflecting step.

11. A method, as claimed in claim 7, wherein:

said comparing step comprises comparing an intensity of said calibration light from said directing step with an intensity associated with said first portion of said calibration light from said reflecting step.

12. A method, as claimed in claim 7, wherein:

said comparing step comprises accounting for a maximum amount of said calibration light from said directing step which may be reflected by said inner surface of said window.

13. A method, as claimed in claim 7, further comprising the steps of:

reflecting a second portion of said calibration light from said outer surface of said window; and

prohibiting said second portion of said calibration light from affecting said comparing step.

14. A method, as claimed in claim 7, wherein:

said comparing step comprises determining if there is one of a first and second type of intensity shift between said calibration light from said directing step and said first portion of said calibration light from said reflecting step.

15. A method, as claimed in claim 14, wherein:

said evaluating step comprises accounting for any said first type of intensity shift identified by said determining step by implementing a single calibration factor.

16. A method, as claimed in claim 15, wherein:

said accounting step comprises applying said single calibration factor to said data from said obtaining step at each of said plurality of times.

17. A method, as claimed in claim 14, wherein:

said evaluating step comprises accounting for any said second type of intensity shift identified by said determining step by implementing a plurality of calibration factors.

18. A method, as claimed in claim 17, wherein:

said accounting step comprises applying each of said plurality of calibration factors to different portions of said data from said obtaining step at each of said plurality of times.

19. A method, as claimed in claim 18, wherein:

a first of said plurality of calibration factors is applied to said data which is representative of optical emissions from said conducting step within a first wavelength region, and wherein a second of said plurality of calibration factors is applied to said data which is representative of optical emissions from said conducting step within a second wavelength region which is outside of said first wavelength region.

20. A method, as claimed in claim 14, wherein:

said evaluating step comprises accounting for any said second type of intensity shift identified by said determining step through normalizing data representative of optical emissions from said conducting step at each of said plurality of times for said obtaining step.

21. A method, as claimed in claim 7, wherein:

said comparing step comprises performing a first determining step comprising determining if said window is filtering out optical emissions associated with said conducting step and within a first wavelength region.

22. A method, as claimed in claim 21, wherein said evaluating step comprises:

ignoring said optical emissions within said first wavelength region if said filtering is identified by said performing a first determining step.

23. A method, as claimed in claim 21, wherein said comparing step further comprises the steps of:

identifying a plurality of intensity peaks in said calibration light from said directing step; and

performing a second determining step comprising determining when any of said peaks from said identifying step are at least substantially absent in said first portion of said calibration light from said reflecting step and which defines said first wavelength region.

24. A method, as claimed in claim 21, further comprising the step of:

recommending that said window be replaced if said filtering is identified by said performing a first determining step.

25. A method, as claimed in claim 7, wherein:

said comparing step comprises determining if there is at least one of an intensity shift and a wavelength shift between said calibration light from said directing step and said first portion of said calibration light from said reflecting step.

26. A method, as claimed in claim 1, wherein said window comprises an inner surface which is exposed to said conducting step and an outer surface which is isolated from said conducting step, and wherein said monitoring step comprises:

performing a first calibrating step comprising;

directing a first calibration light toward said window from a location which is exterior of said processing chamber;

reflecting a first portion of said first calibration light from said inner surface said window; and

comparing said first calibration light from said directing a first calibration light step with said first portion of said first calibration light from said reflecting a first portion of said first calibration light step; and

performing a second calibrating step comprising;

directing a second calibration light toward said window from a location which is exterior of said processing chamber, said second calibration light being different from said first calibration light;

reflecting a first portion of said second calibration light from said inner surface said window; and

comparing said second calibration light from said directing a second calibration light step with said first portion of said second calibration light from said reflecting a first portion of said second calibration light step.

27. A method, as claimed in claim 26, wherein:

said performing a first calibrating step comprises accounting for a wavelength shift associated with said obtaining step, said performing a second calibrating step accounting for an intensity shift associated with said obtaining step.

28. A method, as claimed in claim 27, wherein:

said first calibration light comprises a plurality of discrete intensity peaks and wherein said second calibration light comprises a continuum of intensity.

29. A method, as claimed in claim 26, wherein:

said first calibration light comprises a plurality of discrete intensity peaks and wherein said second calibration light comprises a continuum of intensity.

30. A method, as claimed in claim 26, wherein:

said performing a first calibrating step and said performing a second calibrating step are executed at different and non-overlapping times.

31. A method, as claimed in claim 1, wherein said data from said obtaining step comprises optical emissions including wavelengths at least within a first wavelength range of about 200 nanometers to about 1,000 nanometers, and wherein said monitoring step comprises:

determining if said window is filtering out said optical emissions within a first wavelength region which is contained within said first wavelength range.

32. A method, as claimed in claim 1, wherein said data from said obtaining step comprises optical emissions including wavelengths at least within a first wavelength range of about 200 nanometers to about 1,000 nanometers, and wherein said monitoring step comprises:

determining if said window is having a first dampening effect on a first wavelength region which is within said first wavelength range, as well as a second dampening effect on a second wavelength region which is both within said first wavelength range and outside of said first wavelength region.

33. A method, as claimed in claim 1, further comprising the step of:

identifying an effect on said obtaining step by any deposits formed on said inner surface of said window, said identifying step using said monitoring step.

34. A method, as claimed in claim 1, further comprising the step of:

making at least one adjustment in relation to said evaluating step based upon said monitoring step.

35. A method for monitoring a plasma process comprising the steps of:

loading a quantity of product into a processing chamber;

conducting a plasma process on said product in said processing chamber, wherein said processing chamber comprises a window and wherein said window comprises an inner surface which is exposed to said conducting step and an outer surface which is isolated from said conducting step;

obtaining data on said plasma process through said window, wherein said obtaining step is executed at least a plurality of times during said conducting step;

monitoring said window, comprising the steps of;

directing a calibration light toward said window from a location which is exterior of said processing chamber;

reflecting a first portion of said calibration light from said inner surface of said window; and

comparing said calibration light from said directing step with said first portion of said calibration light from said reflecting step; and

evaluating said conducting step using both said obtaining step and said monitoring step.

36. A method, as claimed in claim 35, wherein:

said loading step comprises loading at least one wafer in said processing chamber.

37. A method, as claimed in claim 35, wherein:

said obtaining step comprises obtaining optical emissions of plasma in said processing chamber during said conducting step.

38. A method, as claimed in claim 35, wherein:

said monitoring step comprises monitoring a condition of said window other than through said obtaining step.

39. A method, as claimed in claim 35, wherein:

said monitoring step is terminated during execution of said conducting step.

40. A method, as claimed in claim 35, wherein:

said monitoring step is executed only at one of first and second times, said first time being before execution of said conducting step and said second time being after said execution of said conducting step.

41. A method, as claimed in claim 35, wherein:

said monitoring step comprises assessing first data which is independent of any data relating to plasma in said processing chamber during said conducting step.

42. A method, as claimed in claim 35, wherein:

said comparing step comprises comparing a spectral pattern of said calibration light from said directing step with a spectral pattern of said first portion of said calibration light from said reflecting step.

43. A method, as claimed in claim 42, wherein said spectral pattern of said calibration light from said directing step is within a first range comprising wavelengths from about 200 nanometers to about 1,000 nanometers, said spectral pattern of said first portion of said calibration light from said reflecting step is at least within said first range, and wherein:

said comparing step comprises comparing an intensity of said spectral pattern of said calibration light from said directing step with an intensity of said spectral pattern of said first portion of said calibration light from said reflecting step at least at about every 1 nanometer throughout said first range.

44. A method, as claimed in claim 35, wherein:

said comparing step comprises noting any differences between said calibration light from said directing step with said first portion of said calibration light from said reflecting step.

45. A method, as claimed in claim 35, wherein:

said comparing step comprises comparing an intensity of said calibration light from said directing step with an intensity associated with said first portion of said calibration light from said reflecting step.

46. A method, as claimed in claim 35, wherein:

said comparing step comprises accounting for a maximum amount of said calibration light from said directing step which may be reflected by said inner surface of said window.

47. A method, as claimed in claim 35, further comprising the steps of:

reflecting a second portion of said calibration light from said directing step with said outer surface of said window; and

prohibiting said second portion of said calibration light from affecting said comparing step.

48. A method, as claimed in claim 35, wherein:

said comparing step comprises determining if there is one of a first and second type of intensity shift between said calibration light from said directing step and said first portion of said calibration light from said reflecting step, said method further comprising the step of evaluating said conducting step using both said obtaining step and said monitoring step.

49. A method, as claimed in claim 48, wherein:

said evaluating step comprises accounting for any said first type of intensity shift identified by said comparing step by implementing a single calibration factor.

50. A method, as claimed in claim 49, wherein:

said accounting step comprises applying said single calibration factor to said data from said obtaining step which is used by said evaluating step.

51. A method, as claimed in claim 48, wherein:

said evaluating step comprises accounting for any said second type of intensity shift identified by said comparing step by implementing a plurality of calibration factors.

52. A method, as claimed in claim 51, wherein:

said accounting step comprises applying each of said plurality of calibration factors to different portions of said data from said obtaining step which is used by said evaluating step.

53. A method, as claimed in claim 52, wherein:

a first of said plurality of calibration factors is applied to said data which is representative of optical emissions from said conducting step within a first wavelength region, and wherein a second of said plurality of calibration factors is applied to said data which is representative of optical emissions from said conducting step within a second wavelength region which is outside of said first wavelength region.

54. A method, as claimed in claim 48, wherein:

said evaluating step comprises accounting for any said second type of intensity shift identified by said comparing step through normalizing data representative of optical emissions from said conducting step which is used by said evaluating step.

55. A method, as claimed in claim 35, wherein:

said comparing step comprises performing a first determining step comprising determining if said window is filtering out optical emissions from said conducting step within a first wavelength region.

56. A method, as claimed in claim 55, futher comprising the step of:

evaluating said conducting step using both said obtaining step and said monitoring step, wherein said evaluating step comprises ignoring said optical emissions within said first wavelength region if said filtering is identified by said performing a first determining step.

57. A method, as claimed in claim 55, wherein said comparing step further comprises the steps of:

identifying a plurality of intensity peaks in said calibration light from said directing step; and

performing a second determining step comprising determining when any of said peaks from said identifying step are at least substantially absent in said first portion of said calibration light from said reflecting step and which defines said first wavelength region.

58. A method, as claimed in claim 55, further comprising the step of:

recommending that said window be replaced if said filtering is identified by said performing a first determining step.

59. A method, as claimed in claim 35, wherein:

said directing step comprises directing a first calibration light toward said window from a location which is exterior of said processing chamber and directing a second calibration light toward said window from a location which is exterior of said processing chamber, said second calibration light being different from said first calibration light;

said reflecting step comprises reflecting a first portion of said first calibration light from said inner surface of said window and reflecting a first portion of said second calibration light from said inner surface of said window; and

said comparing step comprises comparing said first calibration light from said directing a first calibration light step with said first portion of said first calibration light from said reflecting a first portion of said first calibration light step, and comparing said second calibration light from said directing a second calibration light step with said first portion of said second calibration light from said reflecting a first portion of said second calibration light step.

60. A method, as claimed in claim 59, wherein:

said directing a first calibration light step, said reflecting a first portion of said first calibration light step, and said comparing said first calibration light step collectively comprise a performing a first calibrating step, said performing a first calibrating step accounting for a wavelength shift associated with said obtaining step; and

said directing a second calibration light step, said reflecting a first portion of said second calibration light step, and said comparing said second calibration light step collectively comprise a performing a second calibrating step, said performing a second calibrating step accounting for an intensity shift associated with said obtaining step.

61. A method, as claimed in claim 60, wherein:

said first calibration light comprises a plurality of discrete intensity peaks and wherein said second calibration light comprises a continuum of intensity.

62. A method, as claimed in claim 60, wherein:

said performing a first calibrating step and said performing a second calibrating step are executed at different and non-overlapping times.

63. A method, as claimed in claim 59, wherein:

said first calibration light comprises a plurality of discrete intensity peaks and wherein said second calibration light comprises a continuum of intensity.

64. A method, as claimed in claim 35, further comprising the step of:

identifying an effect on said obtaining step by any deposits formed on said inner surface of said window, said identifying step using said monitoring step.

65. A method, as claimed in claim 35, further comprising the steps of:

evaluating said conducting step using both said obtaining step and said monitoring step; and

making at least one adjustment in relation to said evaluating step based upon said monitoring step.