Method and apparatus for monitoring plasma processing operations

• US 6,077,386 A
• Filed: 04/23/1998
• Issued: 06/20/2000
• 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): Gorgos, Kathryn
• Assistant Examiner(s): SMITH HICKS, ERICA D
• Application Number:
  US09/065,680
• Time in Patent Office: 789 Days
• Field of Search: 204/298.02, 204/298.03, 156/345 MT, 118/712, 118/713, 118/715
• US Class Current: 156/345.24
• 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 plasma processing system, comprising:

a processing chamber comprising a window, wherein said window comprises an inner surface which is exposed to a plasma process conducted within said chamber and an outer surface which is isolated from said plasma process;

means for generating a plasma within said processing chamber to conduct said plasma process within said processing chamber;

means for obtaining optical emissions of said plasma within said chamber which are emitted through said window during said plasma process;

means for evaluating said plasma process through output from said means for obtaining; and

a calibration assembly operatively interconnected with said means for evaluating, said calibration assembly comprising means for calibrating said means for evaluating for each of first and second conditions, said first condition being a wavelength shift associated with said optical emissions which are used by said means for evaluating, said second condition being an intensity shift associated with said optical emissions which are used by said means for evaluating.

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

said means for obtaining comprises at least one spectrometer.

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

said means for evaluating comprises means for comparing a pattern of said optical emissions from a current said plasma process with a pattern of previous-in-time optical emissions from at least one said plasma process.

4. A system, as claimed in claim 1, wherein said means for calibrating comprises:

means for directing a calibration light to said window; and

means for comparing a portion of said calibration light reflected by said window with said calibration light from said means for directing.

5. A system, as claimed in claim 4, wherein:

said means for calibrating further comprises means for limiting said portion of said calibration light used by said means for comparing to a portion of said calibration light from said means for directing which is reflected by said inner surface of said window.

6. A system, as claimed in claim 5, wherein:

said means for limiting comprises means for directing said calibration light to said window to impact said outer surface of said window at an angle other than perpendicular relative to said outer surface to direct at least substantially all portions of said calibration light reflected by said outer surface of said window so as to be unavailable for use by said means for comparing, and such that a portion of said calibration light impacts said inner surface of said window to direct at least a portion of said calibration light reflected by said inner surface of said window so as to be available for use by said means for comparing.

7. A system, as claimed in claim 5, wherein:

said means for limiting comprises an anti-reflective coating on at least a portion of said outer surface of said window.

8. A system, as claimed in claim 4, wherein:

said means for comparing comprises means for comparing a pattern of said calibration light from said means for directing with a pattern of said portion of said calibration light reflected by said window.

9. A system, as claimed in claim 1, wherein:

said optical emissions associated with said means for obtaining are within a first wavelength range, and wherein said calibration assembly further comprises means for determining if said window is filtering out said optical emissions within a first wavelength region which is contained within said first wavelength range.

10. A system, as claimed in claim 1, wherein:

said optical emissions associated with said means for obtaining are within a first wavelength range, and wherein said calibration assembly further comprises means for 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, wherein said first and second dampening effects are different.

11. A system, as claimed in claim 1, wherein:

said means for calibrating comprises a first calibration light source and a second calibration light source, said first calibration light source being of a different type of light than said second calibration light source.

12. A system, as claimed in claim 11, wherein:

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

13. A system, as claimed in claim 12, wherein:

said first calibration light source is used by said means for calibrating to identify said first condition and said second calibration light source is used by said means for calibrating to identify said second condition.

14. A system, as claimed in claim 1, wherein:

said means for obtaining comprises a first fiber optic cable assembly and said means for calibrating comprises a second fiber optic cable assembly, said system further comprising a fiber optic cable fixture assembly, wherein said fixture assembly comprises a recessed region which interfaces with at least a portion of said outer surface of said window and a first port which extends through said fixture assembly to intersect with said recessed region, wherein at least a portion of said fixture assembly which defines said recessed region comprises a light absorbing material, wherein first ends of said first and second fiber optic cable assemblies are attached to said fixture assembly in axial alignment with said first port, and wherein said window is configured and said fixture assembly is disposed relative to said window such that a reference axis projecting from said first ends of said first and second fiber optic cable assemblies toward said window each intersect said outer surface of said window at an angle other than perpendicular and each intersect said inner surface of said window at least at a substantially perpendicular angle.

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

said first ends of said first and second fiber optic cable assemblies are coaxially disposed and threadably interconnected with said fixture assembly.

16. A plasma processing system, comprising:

a processing chamber comprising a window, wherein said window comprises an inner surface which is exposed to a plasma process conducted within said chamber and an outer surface which is isolated from said plasma process;

means for generating a plasma within said processing chamber to conduct said plasma process within said processing chamber;

means for obtaining optical emissions of said plasma within said chamber which are emitted through said window during said plasma process, said optical emissions being within a first wavelength range;

means for evaluating said plasma process through output from said means for obtaining; and

a calibration assembly operatively interconnected with said means for evaluating, said calibration assembly comprising means for determining if said window is filtering out any said optical emissions within a first wavelength region which is contained within said first wavelength range.

17. A system, as claimed in claim 16, wherein:

said means for obtaining comprises at least one spectrometer.

18. A system, as claimed in claim 16, wherein:

said means for evaluating comprises means for comparing a pattern of said optical emissions from a current said plasma process with a pattern of previous-in-time optical emissions from at least one said plasma process.

19. A system, as claimed in claim 16, wherein said means for determining comprises:

means for directing a calibration light to said window; and

means for comparing a portion of said calibration light reflected by said window with said calibration light from said means for directing.

20. A system, as claimed in claim 19, wherein:

said means for determining further comprises means for limiting said portion of said calibration light used by said means for comparing to a portion of said calibration light from said means for directing which is reflected by said inner surface of said window.

21. A system, as claimed in claim 20, wherein:

said means for limiting comprises means for directing said calibration light to said window to impact said outer surface of said window at an angle other than perpendicular relative to said outer surface to direct at least substantially all portions of said calibration light reflected by said outer surface of said window so as to be unavailable for use by said means for comparing, and such that a portion of said calibration light impacts said inner surface of said window to direct at least a portion of said calibration light reflected by said inner surface of said window so as to be available for use by said means for comparing.

22. A system, as claimed in claim 20, wherein:

said means for limiting comprises an anti-reflective coating on at least a portion of said outer surface of said window.

23. A system, as claimed in claim 19, wherein:

said means for determining comprises means for comparing a pattern of said calibration light from said means for directing with a pattern of said portion of said calibration light reflected by said window.

24. A system, as claimed in claim 19, wherein:

said calibration assembly further comprises means for identifying a wavelength shift associated with said means for evaluating.

25. A system, as claimed in claim 24, wherein:

said means for directing comprises means for directing a first calibration light to said window, said means for identifying comprises means for directing a second calibration light to said window, said first calibration light being of a different type of light than said second calibration light.

26. A system, as claimed in claim 25, wherein:

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

27. A system, as claimed in claim 16, wherein:

said means for obtaining comprises a first fiber optic cable assembly and said calibration assembly comprises a second fiber optic cable assembly, said system further comprising a fiber optic cable fixture assembly, wherein said fixture assembly comprises a recessed region which interfaces with at least a portion of said outer surface of said window and a first port which extends through said fixture assembly to intersect with said recessed region, wherein at least a portion of said fixture assembly which defines said recessed region comprises a light absorbing material, wherein first ends of said first and second fiber optic cable assemblies are attached to said fixture assembly in axial alignment with said first port, and wherein said window is configured and said fixture assembly is disposed relative to said window such that a reference axis projecting from said first ends of said first and second fiber optic cable assemblies toward said window each intersect said outer surface of said window at an angle other than perpendicular and each intersect said inner surface of said window at least at a substantially perpendicular angle.

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

said first ends of said first and second fiber optic cable assemblies are coaxially disposed and threadably interconnected with said fixture assembly.

29. A system, as claimed in claim 16, wherein:

said calibration assembly further comprises means for determining if said window is having a first dampening effect on a second wavelength region which is both within said first wavelength range and outside of said first wavelength region, as well as a second dampening effect on a third wavelength region which is both within said first wavelength range and outside of each of said first and second wavelength regions, wherein said first and second dampening effects are different.

30. A system, as claimed in claim 16, wherein:

said calibration assembly further comprises means for calibrating said means for evaluating for each of first and second conditions, said first condition being a wavelength shift associated with said optical emissions which are used by said means for evaluating, said second condition being an intensity shift associated with said optical emissions which are used by said means for evaluating.

31. A plasma processing system, comprising:

a processing chamber comprising a window, wherein said window comprises an inner surface which is exposed to a plasma process conducted within said chamber and an outer surface which is isolated from said plasma process;

means for generating a plasma within said processing chamber to conduct said plasma process within said processing chamber;

means for obtaining optical emissions of said plasma within said chamber which are emitted through said window during said plasma process, said optical emissions being within a first wavelength range;

means for evaluating said plasma process through output from said means for obtaining; and

a calibration assembly operatively interconnected with said means for evaluating, said calibration assembly means for 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, wherein said first and second dampening effects are different.

32. A system, as claimed in claim 31, wherein:

said means for obtaining comprises at least one spectrometer.

33. A system, as claimed in claim 31, wherein:

said means for evaluating comprises means for comparing a pattern of said optical emissions from a current said plasma process with a pattern of previous-in-time optical emissions from at least one said plasma process.

34. A system, as claimed in claim 31, wherein:

said means for determining comprises means for directing a calibration light to said window; and

means for comparing a portion of said calibration light reflected by said window with said calibration light from said means for directing.

35. A system, as claimed in claim 34, wherein:

said means for determining further comprises means for limiting said portion of said calibration light used by said means for comparing to a portion of said calibration light from said means for directing which is reflected by said inner surface of said window.

36. A system, as claimed in claim 34, wherein:

said means for limiting comprises means for directing said calibration light to said window to impact said outer surface of said window at an angle other than perpendicular relative to said outer surface to direct at least substantially all portions of said calibration light reflected by said outer surface of said window so as to be unavailable for use by said means for comparing, and such that a portion of said calibration light impacts said inner surface of said window to direct at least a portion of said calibration light reflected by said inner surface of said window so as to be available for use by said means for comparing.

37. A system, as claimed in claim 34, wherein:

said means for limiting comprises an anti-reflective coating on at least a portion of said outer surface of said window.

38. A system, as claimed in claim 34, wherein:

said means for determining comprises means for comparing a pattern of said calibration light from said means for directing with a pattern of said portion of said calibration light reflected by said window.

39. A system, as claimed in claim 34, wherein:

said calibration assembly further comprises means for identifying a wavelength shift associated with said means for evaluating.

40. A system, as claimed in claim 39, wherein:

said means for directing comprises means for directing a first calibration light to said window, said means for identifying comprises means for directing a second calibration light to said window, said first calibration light being of a different type of light than said second calibration light.

41. A system, as claimed in claim 40, wherein:

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

42. A system, as claimed in claim 34, wherein:

said means for obtaining comprises a first fiber optic cable assembly and said means for calibration assembly comprises a second fiber optic cable assembly, said system further comprising a fiber optic cable fixture assembly, wherein said fixture assembly comprises a recessed region which interfaces with at least a portion of said outer surface of said window and a first port which extends through said fixture assembly to intersect with said recessed region, wherein at least a portion of said fixture assembly which defines said recessed region comprises a light absorbing material, wherein first ends of said first and second fiber optic cable assemblies are attached to said fixture assembly in axial alignment with said first port, and wherein said window is configured and said fixture assembly is disposed relative to said window such that a reference axis projecting from said first ends of said first and second fiber optic cable assemblies toward said window each intersect said outer surface of said window at an angle other than perpendicular and each intersect said inner surface of said window at least at a substantially perpendicular angle.

43. A system, as claimed in claim 42, wherein:

said first ends of said first and second fiber optic cable assemblies are coaxially disposed and threadably interconnected with said fixture assembly.

44. A system, as claimed in claim 31, wherein:

said calibration assembly further comprises means for determining if said window is filtering out any said optical emissions within a third wavelength region which is both contained within said first wavelength range and outside of each of said first and second wavelength regions.

45. A system, as claimed in claim 31, wherein:

said calibration assembly further comprises means for calibrating said means for evaluating for each of first and second conditions, said first condition being a wavelength shift associated with said optical emissions which are used by said means for evaluating, said second condition being an intensity shift associated with said optical emissions which are used by said means for evaluating.