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

• US 6,928,395 B2
• Filed: 05/27/2004
• Issued: 08/09/2005
• Est. Priority Date: 08/06/2001
• Status: Expired due to Term

• 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:
  US10/856,183
• Publication Number:
  US 20040225477A1
• Time in Patent Office: 439 Days
• Field of Search: 702/66, 702/67, 702/69, 702/70, 702/72, 702 74- 76, 702/81, 702 84- 86, 702117-120, 702/123, 702/151, 702/159, 702/189, 702/193, 702/FOR.104, 702/FOR.117, 702/FOR.114, 702/FOR.108, 702/FOR.110, 702/FOR.135, 702/FOR.136, 702/FOR.137, 702/FOR.148, 702FOR 155-FOR 157, 702FOR 159-FOR 160, 702/FOR.165, 702/FOR.170, 702/FOR.171, 438 5- 13, 438/800, 118/663, 118/675, 118/679, 356/629, 356/300, 356/326, 356/601, 356/625, 356/630, 356/634, 356/635, 356/636, 356/638, 356/639, 356/640, 356/902, 706/12, 706/20, 706/46, 706/934, 716/4
• 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 setting up a regression optimization, comprising:

receiving a measured signal;

selecting values for one or more members selected from the group consisting of at least one parameter, at least one range associated with the at least one parameter, and at least one resolution associated with the at least one range;

running the regression optimization using the selected values, wherein one or more simulations are run during the regression optimization, and wherein the one or more simulations are compared to the measured signal during the regression optimization;

generating regression results associated with the running of the regression optimization;

analyzing the generated regression results; and

using the generated regression results to adjust at least one member selected from the group consisting of the at least one parameter, the at least one range, and the at least one resolution.

2. The method of claim 1, wherein the measured signal is measured from a grating profile.

3. The method of claim 1, wherein the at least one parameter includes at least one member selected from a top cd, a bottom cd, a sidewall angle, and a thickness.

4. The method of claim 1, wherein running the regression optimization comprises:

a) running a simulation for a set of values for one or more selected parameters within one or more selected ranges;

b) comparing the simulation with the measured signal; and

c) if the comparison in b) does not meet a goodness of fit, iterating a) and b) using another set of values.

5. The method of claim 4, further comprising:

d) before a), determining if the set of values exists in a database;

e) if the set of values does not exist in the database, performing a), b), and c), then storing the set of values and a simulated signal generated during the simulation in the database; and

f) if the set values exists in the database,

i) retrieving a simulated signal corresponding to the set of values from the database;

ii) comparing the simulated signal with the measured signal; and

iii) if the comparison in ii) does not meet the goodness of fit, iterating d), e), and f) using another set of values.

6. The method of claim 5, further comprising:

determining if all value combinations associated with the set of values have been aimed in the database;

if all of the value combinations have not been stored in the database, continuing to perform a) through f); and

if all of the value combinations have been stored in the database, compiling the database into a library.

7. The method of claim 6, wherein determining if all value combinations comprises:

for a selected parameter, a selected range associated with the parameter, and a selected resolution associated with the selected range, determining if all values for the selected parameter within the selected range at the selected resolution have been stored in the database.

8. A method of setting up a regression optimization, comprising:

determining a first set of regression parameters;

receiving a first set of measurements associated with a first profile;

running the regression optimization on the first set of measurements to obtain a first set of resultant parameter values associated with the first profile;

storing the first set of resultant parameter values to a storage location;

receiving a second set of measurements associated with a second profile;

running the regression optimization on the second sat of measurements to obtain a second set of resultant parameter values associated with the second profile; and

determining a second set of regression parameters, wherein the second set of regression parameters is associated with at least one member selected from the group consisting of the first set of resultant parameter values and the second set of resultant parameter values.

9. A method of setting up a regression optimization, comprising:

determining a first set of one or more regression parameter ranges;

receiving a first set of measurements associated with a first profile;

running the regression optimization on the first set of measurements to obtain a first set of resultant parameter values associated with the first profile;

storing the first set of resultant parameter values to a storage location;

receiving a second set of measurements associated with a second profile;

running the regression optimization on the second set of measurements to obtain a second set of resultant parameter values associated with the second profile; and

determining a second set of one or more regression parameter ranges, wherein the second set one or more regression parameter ranges is associated with at least one member selected from the group consisting of the first set of resultant parameter values and the second set of resultant parameter values.

10. A computer program product for use in setting up a regression optimization, said computer program product comprising:

a computer usable medium including computer readable program code embodied in said medium for causing setting up the regression optimization;

computer readable program code for causing receiving a measured signal;

computer readable program code for causing a computer to effect selecting values for one or more members selected from the group consisting of at least one parameter, at least one range associated with the at least one parameter, and at least one resolution associated with the at least one range;

computer readable program code for causing said computer to effect running the regression optimization using the selected values, wherein one or more simulations are run during the regression optimization, and wherein the one or more simulations are compared to the measured signal during the regression optimization;

computer readable program code for causing said computer to effect generating regression results associated with the running of the regression optimization;

computer readable program code for causing amid computer to effect analyzing the generated regression results; and

computer readable program code for causing said computer to effect using the generated regression results to adjust at least one member selected from the group consisting of the at least one parameter, the at least one range, and the at least one resolution.

12. The computer program product of claim 10, wherein the set of measurements is associated with a grating profile, and wherein the at east one parameter includes at least one member selected from a top cd, a bottom cd, a sidewall angle, and a thickness.

11. An article of manufacture comprising:

a computer usable medium including computer readable program code embodied therein for causing setting up a regression optimization, the computer readable program code in said article of manufacture comprising;

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

computer readable program code for causing said computer to effect selecting values for one or more members selected from the group consisting of at least one parameter, at least one range associated with the at least one parameter, arid at least one resolution associated with the at least one range;

computer readable program code for causing said computer to effect running the regression optimization using the selected values, wherein one or more simulations are run during the regression optimization, and wherein the one or more simulations are compared to the measured signal during the regression optimization;

computer readable program code for causing said computer to effect generateing regression results associated with the running of the regression optimization;

computer readable program code for causing said computer to effect analyzing the generated regression results; and

computer readable program code for causing said computer to effect using the generated regression results to adjust at least one member selected from the group consisting of the at least one parameter, the at least one range, and the at least one resolution.

13. The article of manufacture of claim 11, wherein the set of measurements is associated with a grating profile, and wherein the at least one parameter includes at least one member selected from a top cd, a bottom cd, a sidewall angle, and a thickness.

14. A computer program product for use in setting up a regression optimization, said computer program product comprising:

a computer usable medium including computer readable program code embodied in said medium for setting up the regression optimization;

computer readable program code for causing a computer to effect determining a first set of regression parameters;

computer readable program code for causing said computer to effect receiving a first set of measurements associated with a first profile;

computer readable program code for causing said computer to effect running the regression optimization on the first set of measurements to obtain a first set of resultant parameter values associated with the first profile;

computer readable program code for causing said computer to effect storing the first set of resultant parameter values to a storage location;

computer readable program code for causing said computer to effect receiving a second set of measurements associated with a second profile;

computer readable program code for causing said computer to effect running the regression optimization on the second set of measurements to obtain a second set of resultant parameter values associated with the second profile; and

computer readable program code for causing said computer to effect determining a second set of regression parameters, wherein the second set of regression parameters is associated with at least one member selected from the group consisting of the first set of resultant parameter values and the second set of resultant parameter values.

15. An article of manufacture comprising:

a computer usable medium including computer readable program code embodied therein for causing setting up a regression optimization, the computer readable program coda in said article of manufacture comprising;

computer readable program code for causing a computer to effect determining a first set of regression parameters;

computer readable program code for causing said computer to effect receiving a first set of measurements associated with a first profile;

computer readable program code for causing said computer to effect running the regression optimization on the first set of measurements to obtain a first set of resultant parameter values associated with the first profile;

computer readable program code for causing said computer to effect storing the first set of resultant parameter value to a storage location;

computer readable program code for causing said computer to effect receiving a second set of measurements associated with a second profile;

computer readable program code for causing said computer to effect running the regression optimization on the second set of measurements to obtain a second set of resultant parameter values associated with the second profile; and

computer readable program code for causing said computer to effect determining a second set of regression parameters, wherein the second set of regression parameters is associated with at least one member selected from the group consisting of the first set of resultant parameter values and the second set of resultant parameter values.

16. A computer program product for use in setting up a regression optimization, said computer program product comprising:

a computer usable medium including computer readable program code embodied in said medium for setting up the regression optimization;

computer readable program code for causing a computer to effect determining a first set of one or more regression parameter ranges;

computer readable program code for causing said computer to effect receiving a first set of measurements associated with a first profile;

computer readable program code for causing said computer to effect running the regression optimization on the first set of measurements to obtain a first set of resultant parameter values associated with the first profile;

computer readable program code for causing said computer to effect storing the first set of resultant parameter values to a storage location;

computer readable program code for causing said computer to effect receiving a second set of measurements associated with a second profile;

computer readable program coda for causing said computer to effect running the regression optimization on the second set of measurements to obtain a second set of resultant parameter values associated with the second profile; and

computer readable program code for causing said computer to effect determining a second set of one or more regression parameter ranges, wherein the second set one or more regression parameter ranges is associated with at least one member selected from the group consisting of the first set of resultant parameter values and the second set of resultant parameter values.

17. An article of manufacture comprising:

a computer usable medium including computer readable program code embodied therein for causing setting up a regression optimization, the computer readable program code in said article of manufacture comprising;

computer readable program code for causing a computer to effect determining a first met of one or more regression parameter ranges;

computer readable program code for causing said computer to effect receiving a first set of measurements associated with a first profile;

computer readable program code for causing said computer to effect running the regression optimization on the first set of measurements to obtain a first set of resultant parameter values associated with the first profile;

computer readable program code for causing said computer to effect storing the first set of resultant parameter values to a storage location;

computer readable program code for causing said computer to effect receiving a second set of measurements associated with a second profile;

computer readable program code for causing said computer to effect running the regression optimization on the second set of measurements to obtain a second set of resultant parameter values associated with the second profile; and

computer readable program code for causing said computer to effect determining a second set of one or more regression parameter ranges, wherein the second set one or more regression parameter ranges is associated with at least one member selected from the group consisting of the first set of resultant parameter values and the second set of resultant parameter values.

18. A method of setting up a regression optimization, comprising:

obtaining a measured signal of a structure, wherein the measured signal is measured using an optical metrology device;

selecting a parameter from a set of parameters that characterize a profile for the structure;

selecting a range over which the parameter is to be varied;

selecting a resolution for the range;

running the regression optimization using the selected parameter, range, and resolution, wherein one or more simulations are run during the regression optimization, and wherein one or more simulations are compared to the measured signal during the regression on optimization;

obtaining regression results associated with the running of the regression optimization; and

adjusting the selected range based on the regression results.

19. The method of claim 18, wherein the structure is a grating.

20. The method of claim 18, wherein the parameter includes at least one member selected from a top critical dimension (cd), a bottom cd, a sidewall angle, and a thickness.

21. The method of claim 18, wherein running the regression optimization comprises:

a) running a simulation for a set of values for the selected parameter within the selected range to generate a simulated signal;

b) comparing the simulated signal with the measured signal; and

c) if the comparison in b) does not meet a goodness of fit;

storing the set of values and the simulated signal in a database; and

iterating a) and b) using another set of values for the selected parameter within the selected range and at the selected resolution.

22. The method of claim 21, further comprising:

d) before a), determining if the set of values exists in the database;

e) if the set of values does not exist in the database, performing a), b), and c); and

f) if the set of values exists in the database,

i) retrieving a simulated signal corresponding to the set of values from the database;

ii) comparing the simulated signal with the measured signal; and

iii) if the comparison in ii) does not meet the goodness of fit, iterating d), e), and f) using another set of values for the selected parameter within the selected range and at the selected resolution.

23. The method of claim 22, further comprising:

determining if all value combinations for the selected parameter within the selected range at the selected resolution have been stored in the database;

if all of the value combinations have not been stored in the database, continuing to perform a) through f); and

if all of the value combinations have been stored in the database, compiling the database into a library.

24. A computer-readable storage medium containing computer executable instructions for causing a computer to set up a regression optimization, comprising instructions for:

obtaining a measured signal of a structure, wherein the measured signal is measured using an optical metrology device;

selecting a parameter from a set of parameters that characterize a profile for the structure;

selecting a range over which the parameter is to be varied;

selecting a resolution for the range;

running the regression optimization using the selected parameter, range, and resolution, wherein one or more simulations are rum during the regression optimization, sad wherein one or more simulations are compared to the measured signal during the regression optimization;

obtaining regression results associated with the running of the regression optimization; and

adjusting the selected range based on the regression results.

25. The computer-readable storage medium of claim 24, wherein the structure is a grating.

26. The computer-readable storage medium of claim 24, wherein the parameter includes at least one member selected from a top critical dimension (cd), a bottom cd, a sidewall angle, and a thickness.

27. The computer-readable storage medium of claim 24, wherein running the regression optimization comprises:

a) running a simulation for a set of values for the selected parameter within the selected range to generate a simulated signal;

b) comparing the simulated signal with the measured signal; and

c) if the comparison in b) does not meet a goodness of fit;

storing the set of values and the simulated signal in a database; and

iterating a) and b) using another set of values for the selected parameter within the selected range and at the selected resolution.

28. The computer-readable storage medium of claim 27, further comprising instructions for:

d) before a), determining if the set of values exists in the database;

e) if the set of values does not exist in the database, performing a), b), and c); and

f) if the set of values exist In the database,

i) retrieving a simulated signal corresponding to the set of values from the database;

ii) comparing th simulated signal with the measured signal; and

iii) if the comparison in ii) does not meet the goodness of fit, iterating d), e), and f) using another set of values for the selected parameter within the selected range and at the selected resolution.

29. The computer-readable storage medium of claim 28, further comprising instructions for:

determining if all value combinations for the selected parameter within the selected range at the selected resolution have been stored in the database;

if all of the value combinations have not been stored in the database, continuing to perform a) through f); and

if all of the value combinations have been stored in the database, compiling the database into a library.