Method and apparatus for monitoring plasma processing operations

• US 6,419,801 B1
• Filed: 04/23/1998
• Issued: 07/16/2002
• 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: Ward, Pamela Peardon Denise, Smith, Michael Lane Jr., Stevenson, Joel OʼDon
• Primary Examiner(s): Kalafut, Stephen
• Assistant Examiner(s): Mercado, Julian A.
• Application Number:
  US09/065,358
• Time in Patent Office: 1,545 Days
• Field of Search: 209/192.13, 209/192.32, 209/192.33, 209/298.3, 209/298.31, 209/298.32, 156/345, 216/59, 216/60
• US Class Current: 204/192.13
• 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 selecting at least one endpoint indicator for a plasma process to be run in a processing chamber and which has at least a first endpoint, said method comprising the steps of:

running a first plasma process in said processing chamber;

obtaining optical emissions of plasma in said processing chamber throughout at least a substantial portion of said running step, wherein said obtaining step comprises obtaining optical emissions which includes at least wavelengths from about 250 nanometers to about 1,000 nanometers, inclusive, which defines a first wavelength range, and at a first wavelength resolution throughout an entirety of said first wavelength range, wherein said first wavelength resolution is defined as a wavelength spacing between each adjacent pair of wavelengths obtained throughout said first wavelength range by said obtaining step, wherein said first wavelength resolution is no more than about 1 nanometer such that said obtaining step obtains said optical emissions at least at 751 different wavelengths;

analyzing said optical emissions from said obtaining step to identify at least one said wavelength as a possible endpoint indicator candidate for said first plasma process, wherein said analyzing step comprises the steps of;

generating a plot of intensity versus time for each individual said wavelength of said optical emissions obtained by said obtaining step based upon said first wavelength range and said first wavelength resolution, said generating step illustrating a time-based effect of said running step on an intensity of each individual said wavelength of said optical emissions obtained by said obtaining step, based upon said first wavelength range and said first wavelength resolution, wherein said generating step thereby generates a plurality of said plots, with each said plot being specific to a particular said wavelength within said first wavelength range, and wherein said generating step further thereby produces at least 751 said plots of individual said wavelengths;

receiving information on a first time estimate for said first plasma process to reach said first endpoint;

eliminating any said wavelength provided by said obtaining step, based upon said first wavelength range and said first wavelength resolution, whose corresponding said plot fails to display a distinct change in intensity at a time at least generally corresponding with said first time estimate, wherein each said wavelength from said eliminating step is not a said possible endpoint indicator candidate; and

identifying at least one said plot from said generating step which displays a distinct change in intensity at a time at least generally corresponding with said first time estimate, wherein said wavelength which corresponds with said at least one plot from said identifying step is a said possible endpoint indicator candidate;

selecting said wavelength, associated with said at least one said plot from said identifying step of said analyzing step, as a first endpoint indicator of said first endpoint for said first plasma process; and

using optical emissions of said wavelength from said selecting step to call said first endpoint for subsequent executions of the same said first plasma process in the same said processing chamber.

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

said plurality of wavelengths for said generating step are selected without any knowledge of chemistry associated with said first plasma process.

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

said distinct change of said identifying step is a change in a slope of said at least one said plot.

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

said analyzing said optical emissions step further comprises the step of noting a pattern of each said plot from said identifying step, wherein each said pattern encompasses a region which at least potentially corresponds with said first endpoint for said first plasma process step, said method further comprising the step of selecting at least one of said patterns as an endpoint pattern which is indicative of said first endpoint.

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

said generating step comprises generating said plot for each of said wavelengths within said first wavelength range from said optical emissions from said obtaining step which are available based upon said first wavelength resolution.

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

said analyzing step comprises identifying intensity peaks in at least some of said optical emissions segments and determining if any of said intensity peaks from said identifying step at least substantially disappear at about a time where said first endpoint should occur and noting a corresponding said wavelength, wherein said selecting step comprises selecting at least one of said corresponding said wavelengths as said endpoint indicator of said first endpoint.

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

said analyzing step comprises determining if any intensity peaks in at least some of said optical emissions segments first develop at about a time where said first endpoint should occur and noting a corresponding said wavelength, and wherein said selecting step comprises selecting at least one of said corresponding said wavelengths as said endpoint indicator of said first endpoint.

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

said analyzing step comprises identifying intensity peaks in at least some of said optical emissions segments and determining if any of said intensity peaks from said identifying step at least substantially disappear at about a time where said first endpoint should occur and noting a corresponding said wavelength;

said analyzing step further comprises determining if any intensity peaks in at least some of said optical emissions segments first develop at about a time where said first endpoint should occur and noting a corresponding said wavelength;

said selecting step comprises selecting at least one of said corresponding said wavelengths as said endpoint indicator of said first endpoint.

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

said analyzing step comprises identifying an intensity peak from said optical emissions segments which reaches a steady state at about a time where said first endpoint should occur and noting a corresponding said wavelength, wherein said selecting step comprises selecting at least one of said corresponding said wavelengths as said endpoint indicator of said first endpoint.

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

said analyzing step comprises identifying an intensity peak from said optical emissions segments which was at a steady state up until about a time where said first endpoint should occur and at which time said intensity peak experienced a change, and noting a corresponding said wavelength, wherein said selecting step comprises selecting at least one of said corresponding said wavelengths as said endpoint indicator of said first endpoint.

11. A method for selecting at least one endpoint indicator for a plasma process to be run in a processing chamber and which has at least a first endpoint, said method comprising the steps of:

running a first plasma process in said processing chamber on a first product;

obtaining optical emissions of plasma in said processing chamber throughout at least a substantial portion of said running step, wherein said optical emissions include at least wavelengths from about 250 nanometers to about 1,000 nanometers, inclusive, which defines a first wavelength range and at a first wavelength resolution throughout an entirety of said first wavelength range, wherein said first wavelength resolution is defined by a wavelength spacing between each adjacent pair of wavelengths obtained throughout said first wavelength range by said obtaining step, and wherein said first wavelength resolution is no more than about 1 nanometer;

analyzing said optical emissions from said obtaining step, wherein said analyzing step further comprises the step of;

generating a plot of intensity versus time for each of a plurality of wavelengths within said first wavelength range from said optical emissions from said obtaining step, said generating step illustrating a time-based effect of said running step on an intensity of each of said plurality of wavelengths, wherein said running, obtaining, and analyzing steps comprise a run, wherein said method further comprises the steps of;

executing a first said run on a first said first product having a first thickness;

executing a second said run on a second said first product having a second thickness, wherein said first and second thicknesses are different;

identifying at least one said wavelength from said generating steps from said first and second said runs in which a pattern of said plot of said at least one wavelength was substantially the same for each of said first and second said runs, where there is a distinct change in intensity at a time at least generally corresponding with a time at which endpoint should occur in said plot of said at least one wavelength from each of said first and second said runs, and further where said distinct change in said plot of said at least one wavelength from said first and second said runs are temporally spaced;

selecting said at least one said wavelength from said identifying step as a possible candidate as an endpoint indicator of said first endpoint for said first plasma process; and

using said endpoint indicator from said selecting step to call said first endpoint for subsequent executions of the same said first plasma process in the same said processing chamber.