Method and system of dynamic learning through a regression-based library generation process

• US 6,785,638 B2
• Filed: 08/06/2001
• Issued: 08/31/2004
• Est. Priority Date: 08/06/2001
• Status: Active Grant

• Current Assignee: Tokyo Electron America Incorporated (Tokyo Electron Limited)
• Original Assignee: Timbre Technologies Incorporated (Tokyo Electron Limited)
• Inventors: Jakatdar, Nickhil, Niu, Xinhui
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): TSAI, CAROL S W
• Application Number:
  US09/923,578
• Publication Number:
  US 20030028358A1
• Time in Patent Office: 1,121 Days
• Field of Search: 702/66, 702/67, 702/69, 702/70, 702/72, 702/74, 702/75, 702/76, 702/81, 702/84, 702/85, 702/86, 702/117, 702/118, 702/119, 702/120, 702/123, 702/151, 702/159, 702/189, 702/193, 702/FOR.104, 702/FOR.107, 702/FOR.114, 702/FOR.108, 702/FOR.110, 702/FOR.135, 702/FOR-136, 702/FOR.148, 702/FOR-155, 702/FOR.165, 702/FOR-170, 438/573, 438/800, 118/663, 118/675, 118/679, 716/4, 356/369
• US Class Current: 702/189
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G01N 21/211 Ellipsometry optical thickness measurement G01B11/06

Abstract

The present invention relates to a method and system for efficiently determining grating profiles using dynamic learning in a library generation process. The present invention also relates to a method and system for searching and matching trial grating profiles to determine shape, profile, and spectrum data information associated with an actual grating profile.

Claims

1. A method of determining a first actual profile associated with a first grating comprising:

receiving a set of measurements associated with a signal indicative of diffraction from the grating;

generating a first actual spectrum signal data associated with the grating;

selecting a first trial profile;

generating a first trial spectrum signal data associated with the first trial profile;

comparing the first trial spectrum signal data to the first actual spectrum signal data;

determining parameter values for a second trial profile using at least one optimization technique based on the comparison of the first trial spectrum signal data to the first actual spectrum signal data, wherein the second trial profile is associated with a second sample trial spectrum signet data, and wherein the second trial profile matches the first actual profile more closely than the first trial profile; and

storing the second trial profile and the second sample trial spectrum signal data in a dynamic library of profiles.

2. The method of claim 1, wherein the at least one optimization technique includes at least one member selected from the group consisting of a global optimization technique and a local optimization technique.

3. The method of claim 1, further comprising:

using the at least one optimization technique to generate a plurality of additional trial profiles, each of the plurality of additional trial profiles having an associated additional trial spectrum signal data, wherein each additional trial profile generated matches the actual profile more closely than previously generated additional sample profiles.

4. The method of claim 3, further comprising:

storing the additional trial profiles and the additional trial spectrum signal data in the dynamic library of profiles.

5. The method of claim 4, further comprising:

determining a second actual profile associated with a second grating, including;

receiving a second set of measurements to obtain a second actual spectrum signal data associated with the second grating; and

comparing the second actual spectrum signal data to one or more of the spectrum signal data stored in the dynamic library of profiles.

6. The method of claim 5, wherein the step of determining the second actual profile further comprises:

searching the spectrum signal data stored in the dynamic library of profiles for a match with the second actual spectrum signal data, wherein the match satisfies a preset criteria set, and if a watching spectrum signal data is found,

retrieving a matching profile associated with the matching spectrum signal data.

7. The method of claim 5, wherein the step of determining the second actual profile further comprises:

searching the spectrum signal data stored in the dynamic library of profiles for a match with the second actual spectrum signal data, wherein the match satisfies a preset criteria set, and if no matching spectrum signal data is found,

determining a closest matching spectrum signal data stored in the dynamic library of profiles to the second actual spectrum signal data;

retrieving a closest matching profile associated with the closest matching spectrum signal data; and

using at least one of the at least one optimization techniques to iteratively generate additional trial profiles increasingly closer in matching the second actual profile.

8. The method of claim 1, wherein the set of measurements includes at least one member selected from the group consisting of reflectivity and change in polarization states.

9. The method of claim 1, wherein the at least one optimization technique includes a steepest descent technique.

10. A method of determining a profile associated with a grating, comprising:

receiving a measured signal;

selecting a set of trial parameter values;

determining whether the set of trial parameter values is stored in a database, wherein if the set of trial parameter values is stored in the database,

searching the database for a trial signal associated with the set of trial parameter values,

and wherein if the set of trial parameter values is not stored in the database, storing the set of trial parameter values in the database,

performing an electromagnetic simulation associated with the set of trial parameter Values;

generating a simulated signal, and

storing the simulated signal in the database or another storage medium.

11. The method of claim 10, further comprising:

comparing the simulated signal to the measured signal.

12. The method of claim 10, wherein the set of trial parameter values is associated with a set of one or more trial parameters, wherein the set of one or more trial parameters includes at least one member selected from a top cd, a bottom cd, a sidewall angle, and a thickness.

13. The method of claim 11, wherein the step of comparing includes determining whether the trial signal satisfies a goodness of fit criterion.

14. A computer program product for use in determining a first actual profile associated with a first grating, said computer program product comprising:

a computer usable medium including computer readable program code embodied in said medium for causing determining the first actual profile;

computer readable program code for causing a computer to effect receiving a signal indicative of diffraction from the grating;

computer readable program code for causing said computer to effect generating actual spectrum signal data associated with the grating;

computer readable program code for causing said computer to effect selecting a first trial profile;

computer readable program code for causing said computer to effect generating a first trial spectrum signal data associated with the first trial profile;

computer readable program code for causing said computer to effect comparing the first trial spectrum signal data to the first actual spectrum signal data;

computer readable program code for causing said computer to effect determining parameter values for a second trial profile using at least one optimization technique based on the comparison of the first trial spectrum signal data to the first actual spectrum signal data, wherein the second trial profile is associated with a second sample trial spectrum signal data, and wherein the second trial profile matches the first actual profile more closely than the first trial profile; and

computer readable program code for causing said computer to effect storing the second trial profile and the second sample trial spectrum signal data in a dynamic library of profiles.

16. The computer program product of claim 14, further comprising:

computer readable program code for causing said computer to effect using the at least one optimization technique to generate a plurality of additional trial profiles, each of the plurality of additional trial profiles having an associated additional trial spectrum signal data, wherein each additional trial profile generated more closely than previously generated additional sample profiles matches the actual profile.

18. The computer program product of claim 16, further comprising:

computer readable program code for causing said computer to effect storing the additional trial profiles and the additional trial spectrum signal data in the dynamic library of profiles.

20. The computer program product of claim 18, further comprising:

computer readable program code for causing said computer to effect determining a second actual profile associated with a second grating, including;

computer readable program code for causing said computer to effect receiving a second set of measurements to obtain a second actual spectrum signal data associated with the second grating; and

computer readable program code for causing said computer to effect comparing the second actual spectrum signal data to one or more of the spectrum signal data stored in the dynamic library of profiles.

22. The computer program product of claim 20, wherein the step of determining the second actual profile further comprises:

computer readable program code for causing said computer to effect searching the spectrum signal data stored in the dynamic library of profiles for a match with the second actual spectrum signal data, wherein the match satisfies a preset criteria set, and if a matching spectrum signal data is found,

computer readable program code for causing said computer to effect retrieving a matching profile associated with the matching spectrum signal data.

24. The computer program product of claim 20, wherein the step of determining the second actual profile further comprises:

computer readable program code for causing said computer to effect searching the spectrum signal data stored in the dynamic library of profiles for a match with the second actual spectrum signal data, wherein the match satisfies a preset criteria set, and if no matching spectrum signal data is found,

computer readable program code for causing said computer to effect determining a closest matching spectrum signal data stored in the dynamic library of profiles to the second actual spectrum signal data;

computer readable program code for causing said computer to effect retrieving a closest matching profile associated with the closest matching spectrum signal data; and

computer readable program code for causing said computer to effect using at least one of the at least one optimization techniques to iteratively generate additional trial profiles increasingly closer in matching the second actual profile.

26. The computer program product of claim 14, wherein the set of measurements includes at least one member selected from the group consisting of reflectivity and change in polarization states.

15. An article of manufacture comprising:

a computer usable medium including computer readable program code embodied therein for causing determining a first actual profile associated with a first grating, the computer readable program code in said article of manufacture comprising;

computer readable program code for causing a computer to effect receiving a signal indicative of diffraction from the grating;

computer readable program code for causing said computer to effect generating actual spectrum signal data associated with the grating;

computer readable program code for causing said computer to effect selecting a first trial profile;

computer readable program code for causing said computer to effect generating a first trial spectrum signal data associated with the first trial profile;

computer readable program code for causing said computer to effect comparing the first trial spectrum signal data to the first actual spectrum signal data;

computer readable program code for causing said computer to effect determining parameter values for a second trial profile using at least one optimization technique based on the comparison of the first trial spectrum signal data to the first actual spectrum signal data, wherein the second trial profile is associated with a second sample trial spectrum signal data, and wherein the second trial profile matches the first actual profile more closely than the first trial profile; and

computer readable program code for causing said computer to effect storing the second trial profile and the second sample trial spectrum signal data in a dynamic library of profiles.

17. The article of manufacture of claim 15, further comprising:

computer readable program code for causing said computer to effect using the at least one optimization technique to generate a plurality of additional trial profiles, each of the plurality of additional trial profiles having an associated additional trial spectrum signal data, wherein each additional trial profile generated more closely than previously generated additional sample profiles matches the actual profile.

19. The article of manufacture of claim 17, further comprising:

computer readable program code for causing said computer to effect storing the second trial profile, the additional trial profiles and the additional trial spectrum signal date in the dynamic library of profiles.

21. The article of manufacture of claim 19, further comprising:

computer readable program code for causing said computer to effect determining a second actual profile associated with a second grating, including;

computer readable program code for causing said computer to effect receiving a second set of measurements to obtain a second actual spectrum signal data associated with the second grating; and

computer readable program code for causing said computer to effect comparing the second actual spectrum signal data to one or more of the spectrum signal data stored in the dynamic library of profiles.

23. The article of manufacture of claim 21, wherein the step of determining the second actual profile further comprises:

computer readable program code for causing said computer to effect searching the spectrum signal data stored in the dynamic library of profiles for a match with the second actual spectrum signal data, wherein the match satisfies a preset criteria set, and if a matching spectrum signal data is found,

computer readable program code for causing said computer to effect retrieving a matching profile associated with the matching spectrum signal data.

25. The article of manufacture of claim 21, wherein the step of determining the second actual profile further comprises:

computer readable program code for causing said computer to effect searching the spectrum signal data stored in the dynamic library of profiles for a match with the second actual spectrum signal data, wherein the match satisfies a preset criteria set, and if no matching spectrum signal data is found,

computer readable program code for causing said computer to effect determining a closest matching spectrum signal data stored in the dynamic library of profiles to the second actual spectrum signal data;

computer readable program code for causing said computer to effect retrieving a closest matching profile associated with the closest matching spectrum signal data; and

computer readable program code for causing said computer to effect using at least one of the at least one optimization techniques to iteratively generate additional trial profiles increasingly closer in matching the second actual profile.

27. The article of manufacture of claim 15, wherein the set of measurements includes at least one member selected from the group consisting of reflectivity and change in polarization states.

28. A computer program product for use in determining a profile associated with a grating, said computer program product comprising:

a computer usable medium including computer readable program code embodied in said medium for causing determining the profile;

computer readable program code for causing a computer to effect receiving a measured signal;

computer readable program code for causing said computer to effect selecting a set of trial parameter values;

computer readable program code for causing said computer to effect determining whether the set of trial parameter values is cored in a database, wherein if the set of trial parameter values is stored in the database,

computer readable program code for causing said computer to effect searching the database for a trial signal associated with the set of trial parameter values,

and wherein if the set of trial parameter values is not stored in the database,

computer readable program code for causing said computer to effect storing the set of trial parameter values in the database;

computer readable program code for causing said computer to effect performing an electromagnetic simulation associated with the set of trial parameter values;

computer readable program code for causing said computer to effect generating a simulated signal; and

computer readable program code for causing a computer to effect storing the simulated signal in the database or another storage medium.

30. The computer program product of claim 28, further comprising:

computer readable program code for causing said computer to effect comparing the trial signal to the measured signal, wherein the step of comparing includes;

computer readable program code for causing said computer to effect determining whether the trial signal satisfies a goodness of fit criterion.

29. An article of manufacture comprising:

a computer usable medium including computer readable program code embodied therein for causing determining a profile associated with a grating, the computer readable program code in said article of manufacture comprising;

computer readable program code for causing a computer to effect receiving a measured signal;

computer readable program code for causing said computer to effect selecting a set of trial parameter values;

computer readable program code for causing said computer to effect determining whether the set of trial parameter values is stored in a database, wherein if the set of trial parameter values is stored in the database,

computer readable program code for causing said computer to effect searching the database for a trial signal associated with the set of trial parameter values,

and wherein if the set of trial parameter values is not stored in the database,

computer readable program code for causing said computer to effect storing the set of trial parameter values in the database;

computer readable program code for causing said computer to effect performing an electromagnetic simulation associated with the set of trial parameter values;

computer readable program code for causing said computer to effect generating a simulated signal; and

computer readable program code for causing said computer to effect storing the simulated signal in the database or another storage medium.

31. The article of manufacture of claim 29, further comprising:

computer readable program code for causing said computer to effect comparing the trial signal to the measured signal, wherein the step of comparing includes;

computer readable program code for causing said computer to effect determining whether the trial signal satisfies a goodness of fit criterion.

32. A system for determining a first actual profile associated with a first grating comprising:

means for receiving a set of measurements associated with a signal indicative of diffraction from the grating;

means for generating actual spectrum signal data associated with the grating;

means for selecting a first trial profile,

means for generating a first trial spectrum signal data associated with the first trial profile;

means for comparing the first trial spectrum signal data to the first actual spectrum signal data;

means for determining parameter values for a second trial profile using at least one optimization technique based on the comparison of the first trial spectrum signal data to the first actual spectrum signal data, wherein the second trial profile is associated with a second sample trial spectrum signal data, and wherein the second trial profile matches the first actual profile more closely than the first trial profile; and

means for storing the second trial profile and the second sample trial spectrum signal data in a dynamic library of profiles.