Method and apparatus for monitoring plasma processing operations

• US 6,383,402 B1
• Filed: 04/12/1999
• Issued: 05/07/2002
• 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: Smith, Michael Lane Jr., Stevenson, Joel OʼDon, Ward, Pamela Denise Peardon
• Primary Examiner(s): Gulakowski, Randy
• Assistant Examiner(s): Ahmed, Shamim
• Application Number:
  US09/290,903
• Time in Patent Office: 1,121 Days
• Field of Search: 216/60, 216/59, 438/14, 438/16
• US Class Current: 216/60
• 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). Another 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. A final aspect of the present invention relates to a network a plurality of plasma monitoring systems, including with remote capabilities (i.e., outside of the clean room).

Claims

1. A method for monitoring a plasma process in a processing chamber, said method comprising the steps of:

executing a first plasma process within said processing chamber;

obtaining optical emissions data throughout a first wavelength region having a first bandwidth during said first plasma process;

selecting a second wavelength region having a second bandwidth, wherein said second bandwidth is less than said first bandwidth, wherein said second wavelength bandwidth is at least 50 nanometers, and wherein said second wavelength region is totally contained within said first wavelength region;

monitoring a first aspect of said;

first plasma process using a first portion of said optical emissions data from said obtaining step associated with said first plasma process, said first portion of said optical emissions data being limited to said second wavelength region, wherein said monitoring step comprises comparing said first portion of said optical emissions data with optical emissions data from a prior execution of the same said first plasma process in the same said processing chamber.

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

said monitoring step comprises comparing said first portion of said optical emissions data with optical emissions data from a prior execution of the same said first plasma process in the same said processing chamber.

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

an intensity of optical emissions corresponding with said optical emissions data may vary throughout said first plasma process;

said monitoring step further comprises generating a first plot of an area of said fit portion of said optical emissions data versus time; and

said area is defined by said intensity of said first portion of said optical emissions data at a certain point in time of said first plasma process.

5. A method, as claimed in claim 4, further comprising the step of:

displaying said first plot on at least one monitor.

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

said monitoring step further comprises generating a second plot of a change in said area of said first portion of said optical emissions data versus time.

7. A method, as claimed in claim 6, further comprising the step of:

displaying said second plot on at least one monitor.

8. A method, as claimed in claim 6, further comprising the step of:

identifying a first endpoint of said first plasma process when a predetermined event occurs in relation to said second plot.

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

an intensity of optical emissions corresponding with said optical emissions data may vary throughout said first plasma process;

said monitoring step further comprises generating a first plot of a change in areas of said first portion of said optical emissions data versus time; and

said area is defined by said intensity of said first portion of said optical emissions data at a certain point in time of said first plasma.

10. A method, as claimed in claim 9, further comprising the step of:

identifying a first endpoint of said first plasma process when a predetermined event occurs in relation to said plot.

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

selecting a third wavelength region having a third bandwidth, wherein said third bandwidth is less than said first bandwidth, wherein said third wavelength region is totally contained within said first wavelength region, and wherein said second and third wavelength regions are different.

12. A method, as claimed in claim 11, further comprising the step of:

monitoring a second aspect of said first plasma process using a second portion of said optical emissions data from said first plasma process which are limited to said third wavelength region, wherein said first plasma process comprises first and second steps defining said first and second aspects, respectively, wherein said first step of said first plasma process provides a first predetermined result and said second step of said first plasma process provides a second predetermined result which is different from said first predetermined result.

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

said monitoring step further comprises monitoring said first aspect further using a second portion of said optical emissions data from said obtaining step which are limited to said third wavelength region.

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

using a first set of optics, wherein said obtaining step associated with said first plasma process uses said first set of optics, and wherein said method further comprises the steps of;

executing a second plasma process within said processing chamber;

obtaining optical emissions data throughout said first wavelength region during said second plasma process using said first set of optics;

selecting a third wavelength region having a third wavelength bandwidth, wherein said third wavelength region is totally contained within said first wavelength bandwidth, wherein said third wavelength bandwidth is less than said first wavelength bandwidth, and wherein said third wavelength region is different from said second wavelength bandwidth; and

monitoring at least one aspect of said second plasma process step using a portion of said optical emissions data from obtaining step associated with said second plasma process which are limited to said third wavelength region.

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

said monitoring step comprises segregating said optical emissions data from said obtaining step within said second wavelength region from said optical emissions data from said obtaining step throughout that portion of said first wavelength region which does not include said second wavelength region, all without using a hardware filter.

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

displaying first and second data fields on a monitor, wherein said selecting step comprises inputting a first wavelength into said first data field and inputting a second wavelength into said second data field, when extremes of said second wavelength region are defined by said first and second wavelengths.

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

said first plasma process comprises a first endpoint which is when said first plasma process has affected a first predetermined result; and

said monitoring step comprises monitoring said plasma process for said endpoint using said second wavelength region.

17. A method for selecting a first wavelength region for identifying a first endpoint associated with a first plasma process, wherein said first endpoint is when a first predetermined result is affected by said first plasma process, and wherein said first wavelength region has a first bandwidth defined between extremes of said first wavelength region, said method comprising the steps of:

executing said first plasma process within a first processing chamber;

obtaining optical emissions data throughout a second wavelength region during said executing step, wherein an intensity of optical emissions corresponding with said optical emissions data varies during said first plasma process, and wherein said second wavelength region has a second bandwidth defined between extremes of said second wavelength region;

selecting a third wavelength bandwidth which is less than said second wavelength bandwidth;

executing a plotting step for a plurality of different endpoint evaluation wavelength regions within said second wavelength region, wherein each of said endpoint evaluation wavelength regions is defined by said third bandwidth, and wherein said plotting step for each said endpoint evaluation wavelength region comprises the step of generating a plot of a change in area of a portion of said optical emissions data from said endpoint evaluation wavelength region over time, wherein said area is defined by said intensity of said portion of said optical emissions data at a certain point in time of said first plasma process; and

selecting said first wavelength region from a review of a plurality of said plots provided by said executing a plotting step.

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

said second wavelength region comprises wavelengths at least within a range from about 250 nanometers to about 1,000 nanometers; and

said obtaining step comprises obtaining said optical emissions data at least at every 1 nanometer throughout said second wavelength region and at least every 1 second during at least a substantial portion of said first plasma process.

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

said third wavelength bandwidth is about 5 nanometers.

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

said third wavelength bandwidth is no more than about 10 nanometers.

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

adjacent said endpoint evaluation wavelength regions overlap.

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

each endpoint evaluation wavelength region extends from a first extreme to a second extreme, each said first and second extreme corresponding with a specific wavelength and a distance between which corresponds with said third wavelength bandwidth, wherein said method further comprises the step of using a first pattern for selecting said plurality of endpoint evaluation wavelength regions, wherein said first pattern comprises starting at a first wavelength, adding said third wavelength bandwidth onto said first wavelength to define a current said endpoint evaluation wavelength region, adding said third wavelength bandwidth to said second extreme of said current endpoint evaluation wavelength region to define a new said current endpoint evaluation wavelength region, and repeating said adding said third wavelength bandwidth to said second extreme step a plurality of times.

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

said second wavelength region comprises wavelengths at least within a range from about 250 nanometers to about 1,000 nanometer;

said obtaining step comprises obtaining said optical emissions. data at least at every 1 nanometer throughout said first wavelength region and at least every 1 second during at least a substantial portion of said first plasma process;

said third wavelength bandwidth is 5 nanometers; and

said plurality of endpoint evaluation wavelength regions comprises 250 nanometers to 255 nanometers, 255 nanometers to 260 nanometers, 260 nanometers to 265 nanometers, 265 nanometers to 270 nanometers, and so forth to at least the 1,000 wavelength on this basis.

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

said selecting said first wavelength region step comprises identifying at least one of said plots which experiences a certain event at about a time when said first endpoint should occur, and using said endpoint evaluation wavelength region which corresponds with said at least one of said plots as said first wavelength region for identifying said first endpoint.

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

said selecting said first wavelength region step comprises identifying each said plot which experiences a certain event at about a time when said first endpoint should occur and identifying a corresponding said endpoint evaluation wavelength region as a first endpoint candidate, grouping each said first endpoint candidate together into an endpoint grouping where a wavelength separation between any of said first endpoint candidates within said endpoint grouping is no more than about 10 nanometers, and defining said first wavelength region for identifying said first endpoint as being between a smallest wavelength within one of said endpoint groupings and a largest wavelength within the same said endpoint grouping.

26. A method for monitoring a plasma process in a processing chamber, said method comprising the steps of:

executing a first plasma process within said processing chamber;

obtaining optical emissions data throughout a first wavelength region having a first bandwidth during said first plasma process;

selecting a second wavelength region having a second bandwidth, wherein said second bandwidth is less than said first bandwidth and wherein said second wavelength region is totally contained within said first wavelength region;

monitoring a first aspect of said first plasma process using a first portion of said optical emissions data from said obtaining step associated with said first plasma process, said first portion of said optical emissions data being limited to said second wavelength region; and

selecting a third wavelength region having a third bandwidth, wherein said third bandwidth is less than said first bandwidth, wherein said third wavelength region is totally contained within said first wavelength region, and wherein said second and third wavelength regions are different.

27. A method, as claimed in claim 26, further comprising the step of:

monitoring a second aspect of said first plasma process using a second portion of said optical emissions data from said first plasma process which are limited to said third wavelength region, wherein said first plasma process comprises first and second steps defining said first and second aspects, respectively, wherein said first step of said first plasma process provides a first predetermined result and said second step of said first plasma process provides a second predetermined result which is different from said first predetermined result.

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

said monitoring step further comprises monitoring said first aspect further using a second portion of said optical emissions data from said obtaining step which are limited to said third wavelength region.

29. A method for monitoring a plasma process in a processing chamber, said method comprising the steps of:

executing a first plasma process within said processing chamber;

obtaining optical emissions data throughout a first- wavelength region having a first bandwidth during said first plasma process;

selecting a second wavelength region having a second bandwidth, wherein said second bandwidth is less than said first bandwidth and wherein said second wavelength region is totally contained within said first wavelength region;

monitoring a first aspect of said first plasma process using a first portion of said optical emissions data from said obtaining step associated with said first plasma process, said first portion of said optical emissions data being limited to said second wavelength region; and

using a first set of optics, wherein said obtaining step associated with said first plasma process uses said first set of optics, and wherein said method further comprises the steps of;

executing a second plasma process within said processing chamber;

obtaining optical emissions data throughout said first wavelength region during said second plasma process using said first set of optics;

selecting a third wavelength region having a third wavelength bandwidth, wherein said third wavelength region is totally contained within said first wavelength region, wherein said third wavelength bandwidth is less than said first wavelength bandwidth, and wherein said third wavelength region is different from said second wavelength region; and

monitoring at least one aspect of said second plasma process step using a portion of said optical emissions data from obtaining step associated with said second plasma process which are limited to said third wavelength region.