Method and apparatus for monitoring plasma processing operations

• US 6,192,826 B1
• Filed: 04/23/1998
• Issued: 02/27/2001
• 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 OʼDon
• Primary Examiner(s): Knode, Marian C.
• Assistant Examiner(s): Zervigon, Rudy
• Application Number:
  US09/065,203
• Time in Patent Office: 1,041 Days
• Field of Search: 438/719, 395/23, 216/60, 156/626
• US Class Current: 118/723.0AN
• 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 a first plasma step, said method comprising the steps of:

generating a plasma in a processing chamber;

performing said plasma process using said generating step, wherein there is a first endpoint of said first plasma step which is when said first plasma step of said plasma process has produced a first predetermined result;

monitoring a health of said plasma used by said performing step, wherein said monitoring a health step comprises determining if said plasma used by said performing step is behaving at least substantially the same as a plasma used by at least one plasma process previously conducted in the same said processing chamber, wherein said determining step comprises comparing a first pattern of optical emissions of said plasma from said performing step with a second pattern of optical emissions from a plasma used by said at least one plasma process previously conducted within the same said processing chamber, wherein said optical emissions which define each of said first and second patterns are each within a first wavelength range, wherein a spacing between adjacent wavelengths which define each of said first and second patterns is no more than about 1 nanometer, wherein said first wavelength range is at least about 50 nanometers, and wherein said comparing step is executed for a plurality of different times during said performing step; and

monitoring said performing step to identify an occurrence of said first endpoint of said first plasma step, wherein said monitoring said performing step comprises evaluating at least a portion of optical emissions of said plasma from said performing step.

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

said plasma process of said performing step is selected from the group consisting of a plasma recipe which is run on at least one product in said processing chamber, a plasma cleaning operation, a plasma conditioning operation, and a qualification wafer operation.

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

said first wavelength range includes wavelengths at least from about 250 nanometers to about 1,000 nanometers.

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

terminating said monitoring said performing step when said determining step identifies a first condition, said first condition being that said performing step is proceeding other than in accordance with a first standard associated with said performing step.

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

said monitoring said performing step comprises;

obtaining optical emissions of said plasma from said performing step at least a plurality of different times during said performing step;

comparing said optical emissions at each of said plurality of different times from said obtaining step with said optical emissions from an earlier of said plurality of different times from said obtaining step; and

determining when said optical emissions from said comparing step of said monitoring said performing step are within a predetermined amount of each other and equating this with said first endpoint.

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

said optical emissions of said monitoring said performing step at each of said plurality of different times from said obtaining step have an associated pattern, wherein said comparing step of said monitoring said performing step comprises comparing said patterns of said optical emissions from said comparing step of said monitoring said performing step, and wherein said predetermined amount of said determining step of said monitoring said performing step defines when said patterns of said optical emissions from said comparing step of said monitoring said performing step are considered a match.

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

said comparing step of said monitoring said performing step comprises comparing said optical emissions of said monitoring said performing step at a first time of said plurality of different times from said obtaining step with said optical emissions of said monitoring said performing step from an immediately preceding time of said plurality of different times from said obtaining step.

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

said monitoring said performing step comprises;

obtaining optical emissions of said plasma in said processing chamber at least a plurality of different times during said performing step;

comparing said optical emissions of said monitoring said performing step at each of said plurality of different times from said obtaining step with at least one standard;

determining when said optical emissions of said monitoring said performing step from at least one of said plurality of different times from said obtaining step is within a predetermined amount of said at least one standard and equating this with said first endpoint.

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

said at least one standard was obtained from a previous execution of the same said performing step in the same said processing chamber.

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

said at least one standard is stored on a computer-readable storage medium.

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

said optical emissions of said monitoring said performing step at each of said plurality of different times from said obtaining step have an associated pattern, wherein said at least one standard has a standard pattern, wherein said comparing step of said monitoring said performing step comprises comparing said pattern of said optical emissions of said monitoring said performing step at each of said plurality of different times from said obtaining step with said standard pattern, and wherein said predetermined amount of said determining step of said monitoring said performing step defines when said pattern of said optical emissions from at least one of said plurality of different times from said obtaining step and said standard pattern are considered a match.

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

said monitoring said performing step comprises monitoring said performing step for occurrence of said first endpoint using first and second techniques, said first technique being different from said second technique, and wherein said first endpoint is identifiable by at least one of said first and second techniques.

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

said first and second techniques are each selected from the group consisting of determining when there is at least a first change in an impedance of said processing chamber, evaluating optical emissions of said plasma from said performing step over a second wavelength range at least a plurality of times during said performing step, and evaluating at least one individual wavelength of said plasma of said performing step at least a plurality of times during said performing step.

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

said monitoring said performing step comprises determining if there is at least a first change in an impedance of said processing chamber and equating this with said first endpoint.

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

said determining step of said monitoring said performing step is based upon a change in at least a portion of optical emissions of said plasma in said processing chamber during said performing step.

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

said monitoring said performing step comprises evaluating at least one individual wavelength of said plasma in said processing chamber at least a plurality of times during said performing step.

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

said evaluating at least one individual wavelength step comprises using a technique selected from the group consisting of determining when a plot of intensity versus time of said at least one individual wavelength deviates by more than a predetermined amount from a predetermined equation, determining when a time rate of change of a slope of said plot of intensity versus time of said at least one individual wavelength deviates by more than a predetermined amount, and combinations thereof.

18. A method, as claimed in claim 1, wherein said plasma process further comprises a second plasma step which is different from said first plasma step at least through a change in said plasma from said generating step, said method further comprising the steps of:

performing said second plasma step using said introducing step and after said performing said first plasma step, wherein there is a second endpoint of said second plasma step which is when said second plasma step has produced a second predetermined result;

monitoring said performing said second plasma step to identify an occurrence of said second endpoint of said second plasma step; and

terminating said generating step after completion of said performing said second plasma step, wherein said first and second endpoints are identified before said terminating step.

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

said monitoring said performing step comprises obtaining first optical emissions of said plasma from said performing step at each of a plurality of different times during said performing step, and evaluating each of said first optical emissions at each of said plurality of different times from said obtaining step to determine if said first endpoint has occurred.

19. A method for monitoring a plasma process comprising a first plasma step, said method comprising the steps of:

generating a plasma in a processing chamber;

running said first plasma step in said processing chamber using said generating step, wherein there is a first endpoint of said first plasma step which is when said first plasma step has produced a first predetermined result;

performing a first evaluating step comprising evaluating at least one characteristic of said plasma in said processing chamber at each of a plurality of different times during at least a portion of said running step using a first time resolution, wherein said first time resolution means that an amount of time between each adjacent pair of said plurality of different times associated with said performing a first evaluating step is no more than an amount equal to said first time resolution; and

determining if said first endpoint of said first plasma step has occurred, said determining step comprising performing a second evaluating step comprising evaluating data relating to said plasma at each of a plurality of different times during at least a portion of said running step using a second time resolution, wherein said second time resolution means that an amount of time between each adjacent pair of said plurality of different times associated with said performing a second evaluating step is no more than an amount equal to said second time resolution, wherein said second time resolution is of a different magnitude than said first time resolution.

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

said performing a first evaluating step comprises determining if a plasma used by said running step is behaving at least substantially the same as a plasma used by at least one plasma process which was previously conducted in the same said processing chamber, wherein said determining step of said performing a first evaluating step comprises comparing a pattern of optical emissions of said plasma from said running step with a pattern of optical emissions of said plasma from said at least one plasma process which was previously conducted in the same said processing chamber.

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

said first time resolution is greater than said second time resolution.

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

said first time resolution is greater than said second time resolution.