Method and apparatus for monitoring plasma processing operations

• US 6,090,302 A
• Filed: 04/23/1998
• Issued: 07/18/2000
• 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): Jenkins, Daniel J.
• Application Number:
  US09/065,006
• Time in Patent Office: 817 Days
• Field of Search: 216/60
• 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). 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 said processing chamber;

performing said first plasma step 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;

monitoring said performing step to identify an occurrence of said first endpoint, wherein said monitoring step comprises using a first technique comprising the steps of;

obtaining optical emissions of said plasma in said processing chamber within a first wavelength range extending from 250 nanometers to about 1,000 nanometers, from at least a plurality of different times during said performing step, and at least at every 1 nanometer throughout said first wavelength range;

comparing said optical emissions at each of said plurality of different times with a first output; and

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

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

said plasma process 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:

a spacing between each pair of adjacent wavelengths from said obtaining step is selected from the group consisting of equal spacings, unequal spacings, and a combination of equal spacings and unequal spacings.

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

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

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

said first output of said comparing step comprises said optical emissions from an earlier of said plurality of different times from said obtaining step.

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

said first output of said comparing step is said optical emissions from an immediately preceding time from said obtaining step.

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

said first output of said comparing step was obtained from a previous execution of the same said performing step in the same said processing chamber.

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

said first output is stored on a computer-readable storage medium.

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

said monitoring step comprises using a second technique which is different from said first technique, and wherein said first endpoint is identifiable by at least one of said first and second techniques.

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

said second technique is selected from the group consisting of determining when there is at least a first change in an impedance of said processing chamber and evaluating at least one individual wavelength of said plasma in said processing chamber at least a plurality of times during said performing step.

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

said second technique is selected from the group consisting of determining when there is at least a first change in an impedance of said processing chamber, evaluating at least one individual wavelength of said plasma in said processing chamber at least a plurality of times during said performing step in relation to a conformity with a predetermined function, and evaluating at least one individual wavelength of said plasma in said processing chamber at least a plurality of times during said performing step in relation to an output of at least one derivative of said predetermined function.

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

evaluating a condition of said plasma in said processing chamber during said performing step, wherein said condition is a cumulative result of all parameters having an effect on said plasma in said processing chamber.

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

said determining step comprises determining a differential between said optical emissions at each of said plurality of times and said first output, and wherein said predetermined amount is when said differential is free from any substantial peaks.

14. A method, as claimed in claim 1, wherein said plasma process further comprises a second plasma step, said method further comprising the step of:

performing said second plasma step 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 which is different from said first predetermined result;

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

terminating said generating step when said first and second endpoint steps have been identified.