Detecting defects on a wafer using defect-specific information

• US 9,189,844 B2
• Filed: 10/15/2012
• Issued: 11/17/2015
• Est. Priority Date: 10/15/2012
• Status: Active Grant

• Current Assignee: KLA-Tencor Corporation
• Original Assignee: KLA-Tencor Corporation
• Inventors: Wu, Kenong, Wu, Meng-Che, Gao, Lisheng
• Primary Examiner(s): DRENNAN, BARRY T
• Application Number:
  US13/652,377
• Publication Number:
  US 20140105482A1
• Time in Patent Office: 1,128 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G06T 2207/10061 from scanning electron microscope
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/001 using an image reference approach

Abstract

Methods and systems for detecting defects on a wafer using defect-specific information are provided. One method includes acquiring information for a target on a wafer. The target includes a pattern of interest formed on the wafer and a known DOI occurring proximate to or in the pattern of interest. The information includes an image of the target on the wafer. The method also includes searching for target candidates on the wafer or another wafer. The target candidates include the pattern of interest. The target and target candidate locations are provided to defect detection. In addition, the method includes detecting the known DOI in the target candidates by identifying potential DOI locations in images of the target candidates and applying one or more detection parameters to images of the potential DOI locations.

Claims

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

acquiring information for a target on a wafer, wherein the target comprises a pattern of interest formed on the wafer and a known defect of interest having a location that is known and unique relative to a location of the pattern of interest, and wherein the information comprises an image of the target on the wafer acquired by imaging the target on the wafer, the location of the pattern of interest on the wafer, the location of the known defect of interest relative to the pattern of interest, and one or more characteristics computed from the pattern of interest and the known defect of interest;

searching for target candidates on the wafer or on another wafer, wherein the target candidates comprise the pattern of interest; and

detecting the known defect of interest in the target candidates by identifying potential defect of interest locations in images of the target candidates and applying one or more detection parameters to images of the potential defect of interest locations, wherein said detecting is performed using a computer system.

2. The method of claim 1, wherein said acquiring, said searching, and said detecting are not performed using design data for the wafer or the other wafer.

3. The method of claim 1, wherein each of said acquiring, said searching, and said detecting independently uses design data for the wafer or the other wafer.

4. The method of claim 1, wherein acquiring the information for the target comprises importing locations of defect of interest samples.

5. The method of claim 1, wherein acquiring the information for the target comprises grabbing the image of the target on the wafer in known locations of defects of interest using an inspection system.

6. The method of claim 1, wherein acquiring the information for the target comprises specifying size, shape and location of care areas, size, shape and location of templates, and area where the one or more characteristics are determined in the images to which the one or more detection parameters are applied.

7. The method of claim 1, wherein acquiring the information for the target comprises providing a graphics user interface to a user.

8. The method of claim 1, wherein acquiring the information for the target comprises displaying high-resolution images of defect of interest locations.

9. The method of claim 1, wherein acquiring the information for the target comprises grabbing templates for all known defects of interest in one die on the wafer or the other wafer in which said searching will be performed.

10. The method of claim 1, wherein acquiring the information for the target comprises determining a similarity between a template and the image of the target and determining a uniqueness of the pattern of interest relative to other patterns on the wafer.

11. The method of claim 1, wherein the pattern of interest has a width and a height that are shorter than a width and a height, respectively, of dies formed on the wafer and the other wafer.

12. The method of claim 1, wherein the potential defect of interest locations are determined based on locations of the pattern of interest.

13. The method of claim 1, wherein the one or more characteristics comprise one or more characteristics of the known defect of interest.

14. The method of claim 1, wherein the one or more characteristics comprise size, shape, intensity, contrast, or polarity of the known defect of interest.

15. The method of claim 1, wherein micro care areas are generated to cover one or more of the potential defect of interest locations.

16. The method of claim 1, wherein said acquiring and said searching are performed using an inspection system in a setup step before said detecting.

17. The method of claim 1, wherein said acquiring and said searching are performed using different inspection systems of the same type.

18. The method of claim 1, wherein said acquiring and said searching are performed in different dies, and wherein said searching is performed in one die using one or more templates for the target candidates.

19. The method of claim 1, further comprising determining a care area location by correlating a template image for the pattern of interest and the images used for detecting the known defect of interest.

20. The method of claim 1, further comprising selecting one or more characteristics of the target, selecting the one or more detection parameters, and determining one or more parameters of a care area such that defects other than the known defect of interest are not detected in the target candidates.

21. The method of claim 1, further comprising acquiring other images for the wafer or the other wafer and using the other images to detect other defects on the wafer or the other wafer.

22. The method of claim 1, wherein the images to which the one or more detection parameters are applied comprise images generated using a reference image and a test image, and wherein the reference image is a template for the pattern of interest.

23. The method of claim 1, further comprising searching an image of a die on the wafer or the other wafer for the pattern of interest by determining if a template for the target correlates with different portions of the image of the die.

24. The method of claim 1, further comprising creating a template for the pattern of interest and modifying the template by changing the site of the template or flipping, rotating, or processing the template.

25. The method of claim 1, wherein said searching comprises acquiring images for the target candidates using the best optics mode for image matching of the images of the target candidates to an image or a template for the pattern of interest.

26. The method of claim 1, wherein said imaging the target on the wafer is performed using a first optics mode, and wherein the images of the target candidates used for said detecting are acquired using a second optics mode different than the first optics mode.

27. The method of claim 1, wherein said detecting comprising providing the information for the target to a defect detection module in order to identify the potential defect of interest locations accurately.

28. The method of claim 1, wherein said detecting comprising identifying the potential defect of interest locations in the images of the target candidates by correlating a template obtained during setup and the images of the target candidates obtained during said detecting.

29. The method of claim 1, further comprising determining the one or more detection parameters based on the information for the target.

30. The method of claim 1, further comprising determining the one or more detection parameters separately for each type of the target candidates based on images for each type of the target candidates, respectively.

31. The method of claim 1, wherein applying the one or more detection parameters comprises generating difference images using the images of the potential defect of interest locations and a reference image and applying a threshold to signals in the difference images.

32. The method of claim 1, further comprising determining one or more characteristics of a difference image for the potential defect of interest locations, wherein applying the one or more detection parameters comprises applying a threshold to one or more values of the one or more characteristics of the difference image.

33. The method of claim 1, wherein the one or more characteristics comprise one or more characteristics of the known defect of interest, and wherein applying the one or more detection parameters comprises applying a threshold to one or more values of the one or more characteristics determined from the images of the potential defect of interest locations.

34. The method of claim 1, wherein the images of the potential defect of interest locations to which the one or more detection parameters are applied are images of care areas surrounding the potential defect of interest locations, and wherein the care areas are determined based on a size of the known defect of interest that is known and unique to the location of the pattern of interest.

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

acquiring information for a target on a wafer, wherein the target comprises a pattern of interest formed on the wafer and a known defect of interest having a location that is known and unique relative to a location of the pattern of interest, and wherein the information comprises an image of the target on the wafer acquired by imaging the target on the wafer, the location of the pattern of interest on the wafer, the location of the known defect of interest relative to the pattern of interest, and one or more characteristics computed from the pattern of interest and the known defect of interest;

searching for target candidates on the wafer or on another wafer, wherein the target candidates comprise the pattern of interest; and

detecting the known detect of interest in the target candidates by identifying potential defect of interest locations in images of the target candidates and applying one or more detection parameters to images of the potential defect of interest locations.

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

an inspection subsystem configured to acquire information for a target on a wafer, wherein the target comprises a pattern of interest formed on the wafer and a known defect of interest having a location that is known and unique relative to a location of the pattern of interest, and wherein the information comprises an image of the target on the wafer acquired by imaging the target on the wafer;

wherein the inspection subsystem is further configured to search for target candidates on the wafer or on another wafer, wherein the target candidates comprise the pattern of interest; and

a computer system configured to detect the known defect of interest in the target candidates by identifying potential defect of interest locations in images of the target candidates and applying one or more detection parameters to images of the potential defect of interest locations.

37. The system of claim 36, wherein the inspection subsystem is further configured to acquire the information and search for the target candidates without using design data for the wafer or the other water, and wherein the computer system is further configured to detect the known detect of interest without using the design data for the water or the other wafer.

38. The system of claim 36, wherein the inspection subsystem and the computer system are further configured to independently use design data for the wafer or the other wafer to acquire the information, search for the target candidates, and detect the known defect of interest.

39. The system of claim 36, wherein the inspection subsystem is further configured to acquire the information by importing locations of defect of interest samples.

40. The system of claim 36, wherein the inspection subsystem is further configured to acquire the information by grabbing the image of the target on the wafer in known locations of defects of interest.

41. The system of claim 36, wherein the computer system is further configured to acquire the information by specifying size, shape and location of care areas, size, shape and location of templates, and area where the one or more characteristics are determined in the images to which the one or more detection parameters are applied.

42. The system of claim 36, wherein the computer system is further configured to provide a graphics user interface to a user displaying the information acquired for the target.

43. The system of claim 36, wherein the computer system is further configured to acquire the information by displaying high-resolution images of defect of interest locations.

44. The system of claim 36, wherein the inspection subsystem is further configured to acquire the information by grabbing templates for all known defects of interest in one die on the wafer or the other wafer in which the inspection subsystem will search for the target candidates.

45. The system of claim 36, wherein the computer system is further configured to acquire the information by determining a similarity between a template and the image of the target and determining a uniqueness of the pattern of interest relative to other patterns on the wafer.

46. The system of claim 36, wherein the pattern of interest has a width and a height that are shorter than a width and a height, respectively, of dies formed on the wafer and the other wafer.

47. The system of claim 36, wherein the potential defect of interest locations are determined based on locations of the pattern of interest.

48. The system of claim 36, wherein the computer system is further configured to acquire the information by determining one or more characteristics of the known defect of interest.

49. The system of claim 36, wherein the computer system is further configured to acquire the information by determining one or more characteristics comprising size, shape, intensity, contrast, or polarity of the known defect of interest.

50. The system of claim 36, wherein the computer system is further configured to generate micro care areas to cover one or more of the potential defect of interest locations.

51. The system of claim 36, wherein the inspection subsystem is further configured to acquire the information and search for the target candidates in a setup step before the computer system detects the known defect of interest.

52. The system of claim 36, wherein the inspection subsystem is further configured to acquire the information and search for the target candidates in different dies, and wherein the inspection subsystem is further configured to search for the target candidates in one die using one or more templates for the target candidates.

53. The system of claim 36, wherein the computer system is further configured to determine a care area location by correlating a template image for the pattern of interest and the images used for detecting the known defect of interest.

54. The system of claim 36, wherein the computer system is further configured to select one or more characteristics of the target, select the one or more detection parameters, and determine one or more parameters of a care area such that defects other than the known defect of interest are not detected in the target candidates.

55. The system of claim 36, wherein the inspection subsystem is further configured to acquire other images for the wafer or the other wafer, and wherein the computer system is further configured to detect other defects on the wafer or the other wafer using the other images.

56. The system of claim 36, wherein the images to which the one or more detection parameters are applied comprise images generated using a reference image and a test image, and wherein the reference image is a template for the pattern of interest.

57. The system of claim 36, wherein the computer system is further configured to search an image of a die on the wafer or the other wafer for the pattern of interest by determining if a template for the target correlates with different portions of the image of the die.

58. The system of claim 36, wherein the computer system is further configured to create a template for the pattern of interest and modify the template by changing the size of the template or flipping, rotating, or processing the template.

59. The system of claim 36, wherein the inspection subsystem is further configured to search for the target candidates by acquiring images for the target candidates using the best optics mode for image matching of the images of the target candidates to an image or a template for the pattern of interest.

60. The system of claim 36, wherein said imaging the target on the wafer is performed using a first optics mode, and wherein the images of the target candidates used to detect the known defect of interest are acquired using a second optics mode different than the first optics mode.

61. The system of claim 36, wherein the computer system is further configured to detect the known defect of interest by providing the information for the target to a defect detection module in order to identify the potential defect of interest locations accurately.

62. The system of claim 36, wherein the computer system is further configured to detect the known defect of interest by identifying the potential defect of interest locations in the images of the target candidates by correlating a template obtained during setup and the images of the target candidates obtained during detection of the known defect of interest by the computer system.

63. The system of claim 36, wherein the computer system is further configured to determine the one or more detection parameters based on the information for the target.

64. The system of claim 36, wherein the computer system is further configured to determine the one or more detection parameters separately for each type of the target candidates based on images for each type of the target candidates, respectively.

65. The system of claim 36, wherein applying the one or more detection parameters comprises generating difference images using the images of the potential defect of interest locations and a reference image and applying a threshold to signals in the difference images.

66. The system of claim 36, wherein the computer system is further configured to determine one or more characteristics of a difference image for the potential defect of interest locations, and wherein applying the one or more detection parameters comprises applying a threshold to one or more values of the one or more characteristics of the difference image.

67. The system of claim 36, wherein applying the one or more detection parameters comprises applying a threshold to one or more values of one or more characteristics of the known defect of interest determined from the images of the potential defect of interest locations.

68. The system of claim 36, wherein the images of the potential defect of interest locations to which the one or more detection parameters are applied are images of care areas surrounding the potential defect of interest locations, and wherein the care areas are determined based on a size of the known defect of interest having the location that is known and unique relative to the location of the pattern of interest.