Multiple tool and structure analysis

• US 7,478,019 B2
• Filed: 01/26/2005
• Issued: 01/13/2009
• Est. Priority Date: 01/26/2005
• Status: Active Grant

• Current Assignee: The Therma-Wave Incorporated (KLA Corporation)
• Original Assignee: KLA-Tencor Corporation
• Inventors: Zangooie, Shahin, Wen, Youxian, Opsal, Jon, Pois, Heath
• Primary Examiner(s): FREJD, RUSSELL WARREN
• Application Number:
  US11/043,196
• Publication Number:
  US 20060167651A1
• Time in Patent Office: 1,448 Days
• Field of Search: 703/2, 356/237.2, 356/401, 356/601, 356/630, 702/66, 702/179, 702/189, 438/14, 438/680
• US Class Current: 703/2
• CPC Class Codes: G01B 11/0625 with measurement of absorption or reflection
• CPC Class Codes: G05B 13/024 in which a parameter or coefficient is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 15/02 electric

Abstract

Measurement data sets for optical metrology systems can be processed in parallel using Multiple Tool and Structure Analysis (MTSA). In an MTSA procedure, at least one parameter that is common to the data sets can be coupled as a global parameter. Setting this parameter as global allows a regression on each data set to contain fewer fitting parameters, making the process is less complex, requiring less processing capacity, and providing more accurate results. MTSA can analyze multiple structures measured on a single tool, or a single structure measured on separate tools. For a multiple tool recipe, a minimized regression solution can be applied back to each tool to determine whether the recipe is optimized. If the recipe does not provide accurate results for each tool, search parameters and/or spaces can be modified in an iterative manner until an optimized solution is obtained that provides acceptable solutions on each tool.

Claims

1. A method for analyzing a sample, comprising the steps of:

optically measuring a sample on a first tool to obtain a first data set corresponding to a number of first parameters;

optically measuring the sample on a second tool to obtain a second data set corresponding to a number of second parameters;

selecting at least one common parameter for each of the first and second data sets, the common parameter having a substantially identical value for both the first and second data sets;

selecting a mathematical model for the sample;

performing in parallel a regression analysis on each of the first and second data sets using the mathematical model to obtain a first solution, wherein during the regression, the values of the first and second parameters are varied with the value selected for the common parameter being shared in order to minimize the number of fitting parameters in each regression analysis; and

storing the first solution.

2. A method according to claim 1, wherein:

the step of performing in parallel a regression analysis on each of the first and second data sets includes minimizing a residual for each regression analysis.

3. A method according to claim 1, further comprising:

applying the first solution back to each of the first and second tools to determine whether the first solution provides an accurate value for each of the first and second parameters to within a desired specification.

4. A method according to claim 3, further comprising:

altering the mathematical model, by at least one of applying an additional constraint and changing a search space, for at least one of the first and second parameters for which the first solution does not provide an accurate value to within the desired specification; and

performing in parallel a subsequent regression analysis on each of the first and second data sets in order to obtain a second solution.

5. A method according to claim 4, further comprising:

applying the second solution back to each of the first and second data sets to determine whether the second solution provides an accurate value for each of the first and second parameters to within a desired specification.

6. A method according to claim 1, wherein:

the step of performing in parallel a regression analysis on each of the first and second data sets can include performing in parallel a regression analysis on additional data sets, wherein each additional data set includes the at least one global parameter.

7. A method according to claim 1, wherein:

at least one of the first parameters and second parameters includes a parameter selected from the group consisting of thickness, refractive index, azimuth angle, extinction coefficient, dispersion, scattering, crystallinity, and composition.

8. A method according to claim 1, wherein:

the mathematical model includes a weighting function for each of the first and second parameters.

9. A method for analyzing a sample, comprising the steps of:

optically measuring a first structure on a metrology tool to obtain a first data set corresponding to a number of first parameters;

optically measuring a second structure on the metrology tool to obtain a second data set corresponding to a number of second parameters, the first and second structures including at least one common structural component;

selecting at least one common parameter for each of the first and second data sets, the common parameters having a substantially identical value for both the first and second data sets;

selecting a mathematical model for the first and second structures;

performing in parallel a regression analysis on each of the first and second data sets using the mathematical model to obtain a first solution, wherein during the regression, the values of the first and second parameters are varied with the value selected for the common parameter being shared in order to minimize the number of fitting parameters in each regression analysis; and

storing the first solution.

10. A method according to claim 9, wherein:

the step of performing in parallel a regression analysis on each of the first and second data sets includes minimizing a residual for each regression analysis.

11. A method according to claim 9, further comprising:

applying the first solution back to each of the first and second structures to determine whether the first solution provides an accurate value for each of the first and second parameters to within a desired specification.

12. A method according to claim 11, further comprising:

altering the mathematical model, by at least one of applying an additional constraint and changing a search space, for at least one of the first and second parameters for which the first solution does not provide an accurate value to within the desired specification; and

performing in parallel a subsequent regression analysis on each of the first and second data sets in order to obtain a second solution.

13. A method according to claim 12, further comprising:

applying the second solution back to each of the first and second data sets to determine whether the second solution provides an accurate value for each of the first and second parameters to within a desired specification.

14. A method according to claim 9, wherein:

the step of performing in parallel a regression analysis on each of the first and second data sets can include performing in parallel a regression analysis on additional data sets, wherein each additional data set includes the at least one global parameter.

15. A method according to claim 9, wherein:

at least one of the first parameters and second parameters includes a parameter selected from the group consisting of thickness, refractive index, azimuth angle, extinction coefficient, dispersion, scattering, crystallinity, and composition.

16. A method according to claim 9, wherein:

the mathematical model includes a weighting function for each of the first and second parameters.

17. A system for analyzing a sample, comprising:

a source of radiation for illuminating the sample;

a detection device for receiving radiation reflected from the sample and providing an output signal in response thereto; and

a processor for receiving the output signal, the processor having instructions for;

obtaining a first data set corresponding to a number of first parameters for a first structure;

obtaining a second data set corresponding to a number of second parameters for a second structure, the first and second structures including at least one common structural component;

selecting at least one common parameter for each of the first and second data sets, the common parameter having a substantially identical value for both the first and second data sets;

performing in parallel a regression analysis on each of the first and second data sets using a mathematical model to obtain a first solution, wherein during the regression, the values of the first and second parameters are varied with the value selected for the common parameter being shared in order to minimize the number of fitting parameters in each regression analysis.

18. A system according to claim 17, wherein:

the source of radiation includes at least one source of radiation in the range of at least one of visible, infrared, and ultraviolet radiation.

19. A system according to claim 17, wherein:

the first and second structures are formed on a single semiconductor substrate.

20. A system according to claim 17, wherein:

the processor further includes instructions for applying the first solution back to each of the first and second data sets to determine whether the first solution provides an accurate value for each of the first and second parameters to within a desired specification.

21. A system according to claim 20, wherein:

the processor further includes instructions for altering the mathematical model, by at least one of applying an additional constraint and changing a search space, for at least one of the first and second parameters for which the first solution does not provide an accurate value to within the desired specification, and performing in parallel a subsequent regression analysis on each of the first and second data sets in order to obtain a second solution.

22. A system according to claim 21, wherein:

the processor further includes instructions for applying the second solution back to each of the first and second data sets to determine whether the second solution provides an accurate value for each of the first and second parameters to within a desired specification.

23. A system for analyzing a sample, comprising:

a first measurement tool including a first source of radiation for illuminating the sample and a first detection device for receiving radiation reflected from the sample and providing a first output signal in response thereto;

a second measurement tool including a second source of radiation for illuminating the sample and a second detection device for receiving radiation reflected from the sample and providing a second output signal in response thereto; and

a processor for receiving the first and second output signals, the processor having instructions for;

obtaining a first data set corresponding to a number of first parameters for the sample measured using the first measurement tool;

obtaining a second data set corresponding to a number of second parameters for the sample measured using the second measurement tool;

selecting at least one common parameter for each of the first and second data sets, the common parameter having a substantially identical value for both the first and second data sets;

performing in parallel a regression analysis on each of the first and second data sets using a mathematical model to obtain a first solution, wherein during the regression, the values of the first and second parameters are varied with the value selected for the common parameter being shared in order to minimize the number of fitting parameters in each regression analysis.

24. A system according to claim 23, wherein:

the processor further includes instructions for applying the first solution back to each of the first and second data sets to determine whether the first solution provides an accurate value for each of the first and second parameters to within a desired specification.

25. A system according to claim 24, wherein:

the processor further includes instructions for altering the mathematical model, by at least one of applying an additional constraint and changing a search space, for at least one of the first and second parameters for which the first solution does not provide an accurate value to within the desired specification, and performing in parallel a subsequent regression analysis on each of the first and second data sets in order to obtain a second solution.

26. A system according to claim 25, wherein:

the processor further includes instructions for applying the second solution back to each of the first and second data sets to determine whether the second solution provides an accurate value for each of the first and second parameters to within a desired specification.

27. A method for analyzing multiple data sets, comprising the steps of:

obtaining a first data set corresponding to a number of first parameters;

obtaining a second data set corresponding to a number of second parameters;

selecting at least one common parameter for each of the first and second data sets, the common parameter having a substantially identical value for both the first and second data sets;

selecting a mathematical model for the first and second data sets;

performing in parallel a regression analysis on each of the first and second data sets using the mathematical model to obtain a first solution, wherein during the regression, the values of the first and second parameters are varied with the value selected for the common parameter being shared in order to minimize the number of fitting parameters in each regression analysis; and

storing the first solution.

28. A method according to claim 27, further comprising:

applying the first solution back to each of the first and second data sets to determine whether the first solution provides an accurate value for each of the first and second parameters to within a desired specification.

29. A method according to claim 28, further comprising:

altering the mathematical model, by at least one of applying an additional constraint and changing a search space, for at least one of the first and second parameters for which the first solution does not provide an accurate value to within the desired specification; and

performing in parallel a subsequent regression analysis on each of the first and second data sets in order to obtain a second solution.

30. A method according to claim 29, further comprising:

applying the second solution back to each of the first and second data sets to determine whether the second solution provides an accurate value for each of the first and second parameters to within a desired specification.