Method and apparatus for inspecting pattern defects

• US 7,792,352 B2
• Filed: 05/19/2008
• Issued: 09/07/2010
• Est. Priority Date: 11/20/2003
• Status: Active Grant

• Current Assignee: Hitachi High-Tech Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: Sakai, Kaoru, Okabe, Takafumi, Maeda, Shunji
• Primary Examiner(s): Desire; Gregory M
• Application Number:
  US12/123,160
• Publication Number:
  US 20080232674A1
• Time in Patent Office: 841 Days
• Field of Search: 382/145, 382/149, 382/225, 382/227, 382/305
• US Class Current: 382/149
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 21/95607 using a comparative method
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/001 using an image reference approach

Abstract

An apparatus for inspecting pattern defects, the apparatus including: a defect candidate extraction unit configured to perform a defect candidate extraction process by comparing a detected image signal with a reference image signal; and a defect detection unit configured to perform a defect detection process and a defect classification process based on a partial image containing a defect candidate that is extracted by the defect candidate extraction unit, wherein the processes performed by the defect candidate extraction unit and/or the defect detection unit are performed asynchronously with an image acquisition process.

Claims

1. An apparatus for inspecting pattern defects, the apparatus comprising:

an image acquisition unit which acquires an image of a specimen;

a defect candidate extraction unit configured to perform a defect candidate extraction process by comparing a detected image signal with a reference image signal; and

a defect detection unit configured to perform a defect detection process and a defect classification process based on a partial image containing a defect candidate that is extracted by said defect candidate extraction unit,

wherein said image acquisition unit and said defect candidate extraction unit work asynchronously with each other, and

said defect detection unit includes plural defect detectors, each of the plural defect detectors performs the defect detection process and the defect classification process in parallel based on partial images which are different with each other.

2. An apparatus according to claim 1, wherein said plural defect detectors detect defects from differing pairs of images from each other.

3. An apparatus according to claim 1, wherein said plural defect detectors detect defects from differing pairs of specimens from each other.

4. An apparatus for inspecting defects, comprising:

an image acquisition unit which acquires an optical image of a specimen with an image sensor and output an image signal;

a defect candidate extraction unit which processes the image signal output from the image sensor to extract defect candidates from the image signal;

a defect detection unit which detects defects from the defect candidates extracted by said defect candidate extraction unit; and

a display unit which displays information about the defects detected by said defect detection unit,

wherein said image acquisition unit and said defect detection unit work asynchronously with each other, and

said defect detection unit includes plural defect detectors operating concurrently, performing the defect detection process and a defect classification process based on partial images which are different with each other.

5. An apparatus according to claim 4, wherein said defect detection unit further classifies said detected defects into plural defect classes.

6. An apparatus according to claim 4, wherein said image acquisition unit including a light source which emits a light, an illumination optical part which illuminate the specimen with the light emitted from the light source and a light collecting part which collects light from the specimen illuminated by the illumination optical part.

7. An apparatus according to claim 4, wherein said image sensor of said image acquisition unit is a TDI image sensor.

8. An apparatus according to claim 4, wherein said plural defect detectors detect defects from differing pairs of images from each other.

9. An apparatus according to claim 4, wherein said plural defect detectors detect defects from differing pairs of specimens from each other.

10. A method of inspecting defects, comprising:

acquiring an image of a specimen with an image sensor and outputting an image signal;

processing the image signal output from the image sensor and extracting defect candidates from the image signal;

detecting defects from the extracted defect candidates; and

displaying information about the detected defects,

wherein the acquiring the image and the detecting defects are performed asynchronously with each other, and

in the detecting defects, plural defect detectors are used, and each of the plural defect detectors performs a defect detection process and a defect classification process in parallel based on partial images which are different with each other.

11. A method according to claim 10, wherein the detecting defects, further including classifying said detected defects into plural defect classes.

12. A method according to claim 10, wherein the acquiring the image including, emitting a light from a light source, illuminating the specimen with the light and collecting light from the specimen illuminated by the light emitted from the light source.

13. A method according to claim 10, wherein said image sensor is a TDI image sensor.

14. A method according to claim 10, wherein said plural defect detectors detect defects from differing pairs of images from each other.

15. A method according to claim 10, wherein said plural defect detectors detect defects from differing pairs of specimens from each other.

16. An apparatus for inspecting defects, comprising:

an image acquisition unit which acquires with an image sensor an image of a specimen illuminated with light and outputs an image signal;

an image processor unit which processes the image signal output from the image acquisition unit; and

a display unit which displays information processed by the image processor unit,

wherein said image acquisition unit and said image processor unit work asynchronously with each other, and

said image processor unit includes plural defect detectors, each of the plural defect detectors performs a defect detection process and a defect classification process in parallel based on partial images which are different with each other.

17. An apparatus according to claim 16, wherein said image processor unit including a defect candidate extraction part which processes the image signal output from the image acquisition unit to extract defect candidates and a defect detection part which detects defects from the defect candidates extracted by said defect candidate extraction part.

18. An apparatus according to claim 17, wherein said defect detection part further classifies said detected defects into plural defect classes.

19. An apparatus according to claim 16, wherein said image acquisition unit including a light source which emits a light, an illumination optical part which illuminate the specimen with the light emitted from the light source and a light collecting part which collects light from the specimen illuminated by the illumination optical part.

20. An apparatus according to claim 16, wherein said image sensor of said image acquisition unit is a TIDI image sensor.

21. An apparatus according to claim 16, wherein said plural defect detectors detect defects from differing pairs of images from each other.

22. An apparatus according to claim 16, wherein said plural defect detectors detect defects from differing pairs of specimens from each other.

23. A method for inspecting defects, comprising:

acquiring an image of a specimen with an image sensor and outputting an image signal;

processing the output image signal to detect defects; and

displaying information relating to the detected defects on a display screen,

wherein the acquiring the image and the processing the output image signal are preformed asynchronously with each other, and

the processing the output image signal uses plural defect detectors, each of the plural defect detectors performs a defect detection process and a defect classification process in parallel based on partial images which are different with each other.

24. A method according to claim 23, wherein the processing includes a defect candidate extraction sub-operation for extracting defect candidates from the image signal acquired by the acquiring, and a defect detection sub-operation for detecting defects from the defect candidates extracted by said defect candidate extraction sub-operation.

25. A method according to claim 24, wherein in the defect detection, sub-operation, further including a sub-operation of classifying said detected defects into plural defect classes.

26. A method according to claim 23, wherein in the acquiring, the image includes sub-operations of emitting a light, illuminating the specimen with the emitted light and collecting light from the specimen illuminated by the emitted light.

27. A method according to claim 23, wherein in the acquiring the image, said image is acquired with a TDI image sensor.

28. An apparatus according to claim 23, wherein said plural defect detectors detect defects from differing pairs of images from each other.

29. An apparatus according to claim 23, wherein said plural defect detectors detect defects from differing pairs of specimens from each other.