Detecting defects on a wafer

• US 9,053,527 B2
• Filed: 01/02/2013
• Issued: 06/09/2015
• Est. Priority Date: 01/02/2013
• Status: Active Grant

• Current Assignee: KLA-Tencor Corporation (KLA Corporation)
• Original Assignee: KLA-Tencor Corporation (KLA Corporation)
• Inventors: Lang, Jun, Chen, Kan, Gao, Lisheng, Huang, Junqing
• Primary Examiner(s): SHAH, UTPAL D
• Application Number:
  US13/733,133
• Publication Number:
  US 20140185919A1
• Time in Patent Office: 888 Days
• Field of Search: 382/145, 382/149
• US Class Current: 1/1
• CPC Class Codes: G01N 2021/8867 using sequentially two or more inspection runs, e.g. coarse and fine, or detecting then analysing
• CPC Class Codes: G01N 21/8851 Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges G01N21/8806 and G01N21/93 - G01N21/95692 take precedence; optical measurement of dimensions G01B11/00; optical scanning G02B26/10; image transformation G06T3/00; computerised image enhancement G06T5/00; image processing per se for flaw detection G06T7/0002
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G03F 7/70616 Monitoring the printed patterns
• CPC Class Codes: G03F 7/7065 Defects, e.g. optical inspection of patterned layer for defects
• CPC Class Codes: G06T 2207/10152 Varying illumination
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: G06T 7/0008 checking presence/absence

Abstract

Methods and systems for detecting defects on a wafer are provided. One method includes identifying one or more characteristics of first raw output generated for a wafer that correspond to one or more geometrical characteristics of patterned features formed on the wafer and assigning individual output in second raw output generated for the wafer to different segments based on the identified one or more characteristics of the first raw output and based on the individual output in the second raw output and individual output in the first raw output that were generated at substantially the same locations on the wafer such that the one or more geometrical characteristics of the patterned features that correspond to each of the different segments in the second raw output are different.

Claims

1. A computer-implemented method for detecting defects on a wafer, comprising:

acquiring first raw output for a wafer generated using a first optics mode of an inspection system and second raw output generated for the wafer using a second optics mode of the inspection system;

identifying one or more characteristics of the first raw output that correspond to one or more geometrical characteristics of patterned features formed on the wafer;

assigning individual output in the second raw output to different segments based on the identified one or more characteristics of the first raw output and based on the individual output in the second raw output and individual output in the first raw output that were generated at substantially the same locations on the wafer such that the one or more geometrical characteristics of the patterned features that correspond to each of the different segments in the second raw output are different, wherein the one or more geometrical characteristics that correspond to one of the different segments comprise one or more geometrical characteristics of page breaks, and wherein the one or more geometrical characteristics that correspond to another of the different segments comprise one or more geometrical characteristics of array areas;

separately assigning one or more defect detection parameters to the different segments; and

applying the assigned one or more defect detection parameters to the individual output in the second raw output assigned to the different segments to thereby detect defects on the wafer.

2. The method of claim 1, wherein the first and second optics modes are defined by different detectors of the inspection system and the same values for other optical parameters of the inspection system.

3. The method of claim 1, wherein first and second optics modes are defined by different detectors of the inspection system, one or more different values for one or more optical parameters of the inspection system, and the same values for other optical parameters of the inspection system.

4. The method of claim 1, wherein the first and second optics modes are defined by the same detector of the inspection system, one or more different values for one or more optical parameters of the inspection system, and the same values for other optical parameters of the inspection system.

5. The method of claim 1, wherein the first and second optics modes are defined as a combination of the same set of detectors of the inspection system, one or more different values for one or more optical parameters of the inspection system, and the same values for other optical parameters of the inspection system.

6. The method of claim 1, wherein the first and second optics modes are defined as a combination of a subset of detectors of the inspection system, one or more different values for one or more optical parameters of the inspection system, and the same values for other optical parameters of the inspection system.

7. The method of claim 1, wherein the first and second raw output is responsive to light scattered from the wafer.

8. The method of claim 1, wherein the first and second raw output is responsive to light reflected from the wafer.

9. The method of claim 1, wherein the identified one or more characteristics of the first raw output comprise projections along lines within the first raw output.

10. The method of claim 1, wherein the identified one or more characteristics of the first raw output comprise median intensity of the first raw output that corresponds to the one or more geometrical characteristics of the patterned features.

11. The method of claim 1, wherein the one or more geometrical characteristics of the patterned features further comprise edges, shape, texture, a mathematical calculation that defines geometry of the patterned features, or some combination thereof.

12. The method of claim 1, wherein said identifying is performed based on how a design layout of the patterned features will affect the one or more characteristics of the first raw output.

13. The method of claim 1, wherein said identifying is performed while said acquiring is being performed.

14. The method of claim 1, wherein said identifying and said assigning the individual output are performed automatically without user input.

15. The method of claim 1, wherein said assigning the individual output is performed without regard to design data associated with the patterned features.

16. The method of claim 1, wherein said assigning the individual output is performed without regard to intensity of the individual output in the second raw output.

17. The method of claim 1, wherein said assigning the individual output comprises analyzing the identified one or more characteristics of the first raw output and applying thresholds to the individual output of the second raw output.

18. The method of claim 1, wherein the one or more characteristics of the first raw output that correspond to the one or more geometrical characteristics of some of the patterned features cannot be suppressed by filtering.

19. The method of claim 1, wherein the one or more defect detection parameters comprise a threshold to be applied to a difference between the individual output in the second raw output and a reference.

20. The method of claim 1, wherein said separately assigning the one or more defect detection parameters is performed such that defects are detected using the individual output of the second raw output assigned to the different segments with different sensitivities.

21. The method of claim 1, wherein said acquiring is performed in one pass of a multi-pass inspection of the wafer, and wherein the computer-implemented method is not performed for raw output acquired in another pass of the multi-pass inspection.

22. The method of claim 1, wherein said acquiring is performed in one pass of a multi-pass inspection of the wafer, and wherein the computer-implemented method is performed for raw output acquired in another pass of the multi-pass inspection.

23. The method of claim 1, wherein said acquiring is performed in one pass of a multi-pass inspection of the wafer, wherein the computer-implemented method is not performed for raw output acquired in another pass of the multi-pass inspection, wherein additional defects are detected using the raw output acquired in the other pass, and wherein the method further comprises combining the defects and the additional defects to generate inspection results for the wafer.

24. The method of claim 1, wherein said acquiring is performed in one pass of a multi-pass inspection of the wafer, wherein the computer-implemented method is performed for raw output acquired in another pass of the multi-pass inspection, wherein additional defects are detected using the raw output acquired in the other pass, and wherein the method further comprises combining the defects and the additional defects to generate inspection results for the wafer.

25. The method of claim 1, further comprising applying one or more predetermined defect detection parameters to the first or second raw output to detect additional defects on the wafer and combining the defects and the additional defects to generate inspection results for the wafer.

26. A non-transitory computer-readable medium, storing program instructions executable on a computer system for performing a method for detecting defects on a wafer, wherein the method comprises:

acquiring first raw output for a wafer generated using a first optics mode of an inspection system and second raw output generated for the wafer using a second optics mode of the inspection system;

identifying one or more characteristics of the first raw output that correspond to one or more geometrical characteristics of patterned features formed on the wafer;

assigning individual output in the second raw output to different segments based on the identified one or more characteristics of the first raw output and based on the individual output in the second raw output and individual output in the first raw output that were generated at substantially the same locations on the wafer such that the one or more geometrical characteristics of the patterned features that correspond to each of the different segments in the second raw output are different, wherein the one or more geometrical characteristics that correspond to one of the different segments comprise one or more geometrical characteristics of page breaks, and wherein the one or more geometrical characteristics that correspond to another of the different segments comprise one or more geometrical characteristics of array area;

separately assigning one or more defect detection parameters to the different segments; and

applying the assigned one or more defect detection parameters to the individual output in the second raw output assigned to the different segments to thereby detect defects on the wafer.

27. A system configured to detect defects on a wafer, comprising:

an inspection subsystem configured to generate first raw output for a wafer by scanning the wafer using a first optics mode of the inspection subsystem and to generate second raw output for the wafer by scanning the wafer using a second optics mode of the inspection subsystem; and

a computer subsystem configured to;

acquire the first and second raw output;

identify one or more characteristics of the first raw output that correspond to one or more geometrical characteristics of patterned features formed on the wafer;

assign individual output in the second raw output to different segments based on the identified one or more characteristics of the first raw output and based on the individual output in the second raw output and individual output in the first raw output that were generated at substantially the same locations on the wafer such that the one or more geometrical characteristics of the patterned features that correspond to each of the different segments in the second raw output are different, wherein the one or more geometrical characteristics that correspond to one of the different segments comprise one or more geometrical characteristics of page breaks, and wherein the one or more geometrical characteristics that correspond to another of the different segments comprise one or more geometrical characteristics of array areas;

separately assign one or more defect detection parameters to the different segments; and

apply the assigned one or more defect detection parameters to the individual output in the second raw output assigned to the different segments to thereby detect defects on the wafer.

28. The system of claim 27, wherein the first and second optics modes are defined by different detectors of the inspection subsystem and the same values for other optical parameters of the inspection subsystem.

29. The system of claim 27, wherein first and second optics modes are defined by different detectors of the inspection subsystem, one or more different values for one or more optical parameters of the inspection subsystem, and the same values for other optical parameters of the inspection subsystem.

30. The system of claim 27, wherein the first and second optics modes are defined by the same detector of the inspection subsystem, one or more different values for one or more optical parameters of the inspection subsystem, and the same values for other optical parameters of the inspection subsystem.

31. The system of claim 27, wherein the first and second optics modes are defined as a combination of the same set of detectors of the inspection subsystem, one or more different values for one or more optical parameters of the inspection subsystem, and the same values for other optical parameters of the inspection subsystem.

32. The system of claim 27, wherein the first and second optics modes are defined as a combination of a subset of detectors of the inspection subsystem, one or more different values for one or more optical parameters of the inspection subsystem, and the same values for other optical parameters of the inspection subsystem.

33. The system of claim 27, wherein the first and second raw output is responsive to light scattered from the wafer.

34. The system of claim 27, wherein the first and second raw output is responsive to light reflected from the wafer.

35. The system of claim 27, wherein the identified one or more characteristics of the first raw output comprise projections along lines within the first raw output.

36. The system of claim 27, wherein the identified one or more characteristics of the first raw output comprise median intensity of the first raw output that corresponds to the one or more geometrical characteristics of the patterned features.

37. The system of claim 27, wherein the one or more geometrical characteristics of the patterned features further comprise edges, shape, texture, a mathematical calculation that defines geometry of the patterned features, or some combination thereof.

38. The system of claim 27, wherein the computer subsystem is further configured to identify the one or more characteristics based on how a design layout of the patterned features will affect the one or more characteristics of the first raw output.

39. The system of claim 28, wherein the computer subsystem is further configured to identify the one or more characteristics while the computer subsystem acquires the first and second raw output.

40. The system of claim 27, wherein the computer subsystem is further configured to identify the one or more characteristics and assign the individual output in the second raw output to the different segments automatically without user input.

41. The system of claim 27, wherein the computer subsystem is further configured to assign the individual output in the second raw output to the different segments without regard to design data associated with the patterned features.

42. The system of claim 27, wherein the computer subsystem is further configured to assign the individual output in the second raw output to the different segments without regard to intensity of the individual output in the second raw output.

43. The system of claim 27, wherein the computer subsystem is further configured to assign the individual output in the second raw output to the different segments by analyzing the identified one or more characteristics of the first raw output and applying thresholds to the individual output of the second raw output.

44. The system of claim 27, wherein the one or more characteristics of the first raw output that correspond to the one or more geometrical characteristics of some of the patterned features cannot be suppressed by filtering.

45. The system of claim 27, wherein the one or more defect detection parameters comprise a threshold to be applied to a difference between the individual output in the second raw output and a reference.

46. The system of claim 27, wherein the computer subsystem is further configured to separately assign the one or more defect detection parameters such that defects are detected using the individual output of the second raw output assigned to the different segments with different sensitivities.

47. The system of claim 27, wherein the inspection subsystem is further configured to generate the first and second raw output in one pass of a multi-pass inspection of the wafer, and wherein the computer subsystem is not configured to identify the one or more characteristics, assign the individual output, separately assign the one or more defect detection parameters, or apply the assigned one or more defect detection parameters for raw output acquired in another pass of the multi-pass inspection.

48. The system of claim 27, wherein the inspection subsystem is further configured to generate the first and second raw output in one pass of a multi-pass inspection of the wafer, and wherein the computer subsystem is further configured to identify the one or more characteristics, assign the individual output, separately assign the one or more defect detection parameters, and apply the assigned one or more defect detection parameters for raw output acquired in another pass of the multi-pass inspection.

49. The system of claim 27, wherein the inspection subsystem is further configured to generate the first and second raw output in one pass of a multi-pass inspection of the wafer, wherein the computer subsystem is not configured to identify the one or more characteristics, assign the individual output, separately assign the one or more defect detection parameters, or apply the assigned one or more defect detection parameters for raw output acquired in another pass of the multi-pass inspection, wherein additional defects are detected using the raw output acquired in the other pass, and wherein the computer subsystem is further configured to combine the defects and the additional defects to generate inspection results for the wafer.

50. The system of claim 27, wherein the inspection subsystem is further configured to generate the first and second raw output in one pass of a multi-pass inspection of the wafer, wherein the computer subsystem is further configured to identify the one or more characteristics, assign the individual output, separately assign the one or more defect detection parameters, and apply the assigned one or more defect detection parameters for raw output acquired in another pass of the multi-pass inspection, wherein additional defects are detected using the raw output acquired in the other pass, and wherein the computer subsystem is further configured to combine the defects and the additional defects to generate inspection results for the wafer.

51. The system of claim 27, wherein the computer subsystem is further configured to apply one or more predetermined defect detection parameters to the first or second raw output to detect additional defects on the wafer and combine the defects and the additional defects to generate inspection results for the wafer.