Method for determining lithographic focus and exposure

• US 20030048458A1
• Filed: 06/26/2002
• Published: 03/13/2003
• Est. Priority Date: 06/26/2001
• Status: Active Grant

• Current Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Original Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Inventors: Levy, Ady, Dziura, Thaddeus G., Mack, Chris A., Mieher, Walter
• Granted Patent: US 7,382,447 B2
• Time in Patent Office: Days
• US Class Current: 356/601
• CPC Class Codes: G03F 7/70625 Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness
• CPC Class Codes: G03F 7/70641 Focus

Abstract

A method for determining one or more process parameter settings of a photolithographic system is disclosed.

Claims

1. A method for determining process parameter settings of a photolithographic system, the method comprising:

correlating the values of a first set of one or more shape parameters with the values of a first set of one or more process parameters to produce dependencies;

determining the values of a second set of one or more shape parameters associated with one or more structures; and

determining the values of a second set of one or more process parameters associated with forming the one or more structures by comparing the second set of one or more shape parameters with the correlated dependencies.

2. The method as recited in claim 1 wherein multiple shape parameters are correlated with multiple process parameters.

3. The method as recited in claim 2 wherein the process parameters are focus and exposure.

4. The method as recited in claim 2 wherein the process parameters are selected from line width, height, side wall angle, top profile, bottom profile, or resist loss.

5. The method as recited in claim 1 wherein the values of the one or more process parameters associated with forming the one or more structures are determined simultaneously.

6. The method as recited in claim 1 wherein the correlated dependencies are produced using lithographic simulation methods or lithographic measurement methods.

7. The method as recited in claim 1 wherein the values of the first set of shape parameters are derived from scatterometry measurements

8. The method as recited in claim 1 wherein the values of the second set of shape parameters are derived from scatterometry measurements.

9. The method as recited in claim 1 wherein the structures are printed on a production wafer.

10. The method as recited in claim 1 wherein a single shape parameter of the second set of one or more shape parameters is used to solve for a single process parameter of the second set of one or more process parameters.

11. The method as recited in claim 1 wherein more than one shape parameters of the second set of one or more shape parameters are used to simultaneously solve for a single process parameter of the second set of one or more process parameters.

12. The method as recited in claim 1 wherein two or more shape parameters of the second set of one or more shape parameters are used to simultaneously solve for two different process parameters of the second set of one or more process parameters.

13. The method as recited in claim 12 wherein the values of the second set of shape parameters are determined via scatterometry measurements.

14. A method for determining the optimal processing conditions for a lithographic system, the method comprising:

measuring scatterometry measurement sites on a focus exposure matrix wafer using a scatterometry system;

interpreting the scatterometry measurements into shape parameter information associated with the scatterometry measurement sites;

determining focus exposure dependencies of shape parameters using the shape information; and

determining the optimum focus and exposure for the lithographic system from the focus exposure dependencies of shape parameters.

15. The method as recited in claim 14 wherein the scatterometry measurement sites are formed using a different combination of focus and exposure.

16. The method as recited in claim 14 wherein interpreting the scatterometry measurements is performed using iterative regression techniques or library matching techniques.

17. The method as recited in claim 14 wherein interpreting the scatterometry measurements is performed using iterative regression techniques and library matching techniques.

18. The method as recited in claim 14 wherein the focus exposure dependencies of shape parameters are in the form of an equation.

19. The method as recited in claim 14 wherein the focus exposure dependencies of shape parameters are in the form of a Bossung Plot.

20. The method as recited in claim 14 wherein the optimum focus and exposure for the lithographic system are determined by overlapping Bossung Plots.

21. A method of focus exposure monitoring of a lithographic system, comprising:

measuring scatterometry measurement sites on a product or test wafer using a scatterometry system;

interpreting the scatterometry measurements into shape parameter information associated with the scatterometry measurement sites; and

determining the focus and exposure values used to process the test or product wafer by matching the shape parameter information with focus exposure dependencies.

22. The method as recited in claim 21 further comprising:

determining the focus exposure correction required to optimize the lithographic system by comparing the determined focus and exposure values to the nominal focus and exposure values of the lithographic system; and

inputting the focus exposure correction into the lithographic system.

23. The method as recited in claim 21 wherein the focus exposure dependencies are formed by the method comprising:

measuring scatterometry measurement sites on a focus exposure matrix wafer using a scatterometry system;

interpreting the scatterometry measurements into shape parameter information associated with the scatterometry measurement sites; and

determining focus exposure dependencies of shape parameters using the shape information.

24. The method as recited in claim 21 wherein the shape parameter information is interpreted from two or more different scatterometry measurement sites.

25. The method as recited in claim 24 wherein the scatterometry sites differ in shape, pitch, mask construction, position or orientation.

26. A method for determining process parameter settings of a photolithographic system, the method comprising:

correlating the values of a first set of two or more shape parameters with the values of a first set of one or more process parameters to produce dependencies, the values of the first set of two or more shape parameters being determined via scatterometry measurement techniques;

determining the values of a second set of two or more shape parameters associated with one or more structures via scatterometry measurement techniques; and

determining the values of a second set of one or more process parameters associated with forming the one or more structures by comparing the second set of two or more shape parameters with the correlated dependencies.

27. The method as recited in claim 26 wherein the first set of one or more process parameters corresponds to a first set of two or more process parameters, wherein the second set of one or more process parameters corresponds to a second set of two or more process parameters, and wherein the values of the second set of two or more process parameters are determined simultaneously by comparing the second set of two or more shape parameters with the correlated dependencies.

28. The method as recited in claim 26 further comprising:

determining the focus exposure correction required to optimize the lithographic system by comparing the determined focus and exposure values to the nominal focus and exposure values of the lithographic system;

inputting the focus exposure correction into the lithographic system; and

producing wafers with the corrected focus exposure values.

29. A method for determining the optimal aberrations for a lithographic system, the method comprising:

measuring scatterometry measurement sites at multiple locations in the stepper or scanner field on a focus exposure matrix wafer using a scatterometry system;

interpreting the scatterometry measurements into shape parameter information associated with the scatterometry measurement sites;

determining focus exposure dependencies of shape parameters using the shape information; and

determining the optimum focus and exposure for multiple locations in the field of the lithographic system from the focus exposure dependencies of shape parameters; and

analyzing the differences in the optimum focus across the field to determine the optical aberrations of the lithography system.

30. A method for determining the optical aberrations of a photolithographic system, the method comprising:

correlating the values of a first set of two or more shape parameters with the values of a first set of one or more process parameters to produce dependencies, the values of the first set of two or more shape parameters being determined via scatterometry measurement techniques;

determining the values of a second set of two or more shape parameters associated with multiple structures in the lithographic field via scatterometry measurement techniques;

determining the values of a second set of one or more process parameters associated with forming the one or more structures by comparing the second set of two or more shape parameters with the correlated dependencies; and

determining the optical aberrations from the lithographic process parameters determined for the multiple scatterometry measurement sites in the lithographic field.

31. The method as recited in claim 30 wherein the process parameters correspond to focus, numerical aperture, illumination, or coherence.

32. The method as recited in claim 30 wherein the shape parameter information is interpreted from two or more different scatterometry measurement sites and wherein the scatterometry sites differ in shape, pitch, mask construction, position or orientation.

33. The method as recited in claim 30 wherein the determined optical aberrations are used to accept or reject a lithographic system for qualification.

34. The method as recited in claim 30 wherein the determined optical aberrations are used to determine optimum settings of the lithographic system so as to minimize the negative effects of the optical aberrations.

35. The method as recited in claim 30 wherein the determined optical aberrations are used to determine corrections to the lens configuration including lens orientation or clocking in order to optimize the lithographic system and to minimize the negative effects of the optical aberrations.

36. The method as recited in claim 30 wherein the determined optical aberrations are used to determine corrections to the lens design in order to optimize the lithographic system and to minimize the negative effects of the optical aberrations.

37. The method as recited in claim 30 wherein the determined optical aberrations are used to determine corrections to the lens manufacturing process to optimize the lithographic system and to minimize the negative effects of the optical aberrations.

38. The method as recited in claim 30 wherein the determined optical aberrations are used to determine the mask design including feature orientation or mask feature parameters so as to minimize the negative effects of the optical aberrations.

39. A method for determining the optical aberrations of a photolithographic system, the method comprising:

correlating the values of a first set of two or more shape parameters with a first set of focus values to produce dependencies, the values of the first set of two or more shape parameters being determined via scatterometry measurement techniques;

determining the values of a second set of two or more shape parameters associated with multiple structures in the lithographic field via scatterometry measurement techniques;

determining a second set of focus values associated with forming the one or more structures at multiple locations in a lithographic field by comparing the second set of two or more shape parameters with the correlated dependencies, the second set of focus values being used to form focal plan deviations in the lithographic field; and

determining the optical aberrations of the lithographic system from the focal plan deviations.

40. The method as recited in claim 40 wherein the shape parameter information is interpreted from two or more different scatterometry measurement sites and wherein the scatterometry sites differ in shape, pitch, mask construction, position or orientation.

41. The method as recited in claim 40 wherein the determined optical aberrations are used to accept or reject a lithographic system for qualification.

42. The method as recited in claim 40 wherein the determined optical aberrations are used to determine optimum settings of the lithographic system so as to minimize the negative effects of the optical aberrations.

43. The method as recited in claim 40 wherein the determined optical aberrations are used to determine corrections to the lens configuration including lens orientation or clocking in order to optimize the lithographic system and to minimize the negative effects of the optical aberrations.

44. The method as recited in claim 40 wherein the determined optical aberrations are used to determine corrections to the lens design in order to optimize the lithographic system and to minimize the negative effects of the optical aberrations.

45. The method as recited in claim 40 wherein the determined optical aberrations are used to determine corrections to the lens manufacturing process to optimize the lithographic system and to minimize the negative effects of the optical aberrations.

46. The method as recited in claim 40 wherein the determined optical aberrations are used to determine the mask design including feature orientation or mask feature parameters so as to minimize the negative effects of the optical aberrations.

47. A method for determining the optical aberrations of a photolithographic system, the method comprising:

correlating the values of a first set of two or more shape parameters with the focus of the lithographic system values of a first set of one or more process parameters to produce dependencies, the values of the first set of two or more shape parameters being determined via scatterometry measurement techniques;

determining the values of a second set of two or more shape parameters associated with multiple structures in the lithographic field via scatterometry measurement techniques;

determining the focus values associated with forming the one or more structures at multiple locations in the lithographic field by comparing the second set of two or more shape parameters with the correlated dependencies; and

determining the optical aberrations from the focal plan deviations determined for the multiple scatterometry measurement sites in the lithographic field.