System and method for enhanced defect detection with a digital matched filter

Patent metadata

Field	Value
Publication number	US-9734422-B2
Application number	US-201514937409-A
Country	US
Kind code	B2
Filing date	Nov 10, 2015
Priority date	Nov 12, 2014
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

Enhanced defect detection of a sample includes acquiring two or more inspection images from a sample from two or more locations of the sample for a first optical mode. The defect detection also generates an aggregated defect profile based on the two or more inspection images from the two or more locations for the first optical mode for a selected defect type and calculating one or more noise correlation characteristics of the two or more inspection images acquired from the two or more locations for the first optical mode. Defect detection further includes the generation of a matched filter for the first optical mode based on the generated aggregated defect profile and the calculated one or more noise correlation characteristics.

First claim

What is claimed:

1. A method comprising:
acquiring two or more inspection images from a sample from two or more locations of the sample for a first optical mode;
generating an aggregated defect profile based on the two or more inspection images from the two or more locations for the first optical mode for a selected defect type;
calculating one or more noise correlation characteristics of the two or more inspection images acquired from the two or more locations for the first optical mode; and
generating a matched filter for the first optical mode based on the generated aggregated defect profile and the calculated one or more noise correlation characteristics.

2. The method of claim 1 , further comprising:
applying the generated matched filter to an acquired inspection image for the first optical mode to form a first filtered image.

3. The method of claim 2 , wherein the applying the generated matched filter to an acquired inspection image for the first optical mode comprises:
convolving the generated matched filter with an acquired inspection image for the first optical mode.

4. The method of claim 2 , further comprising:
acquiring two or more inspection images from the sample from two or more locations of the sample for an additional optical mode;
generating an additional aggregated defect profile based on the two or more inspection images from the two or more locations for the additional optical mode for a selected defect type;
calculating one or more additional noise correlation characteristics of the two or more inspection images acquired from the two or more locations for the additional optical mode;
generating an additional matched filter for the additional optical mode based on the generated additional aggregated defect profile and the calculated one or more additional noise correlation characteristics; and
applying the additional generated matched filter to at least one of the two or more acquired inspection images for the additional optical mode to form an additional filtered image.

5. The method of claim 4 , further comprising:
comparing the first filtered image to the additional filtered image to rank the first optical mode and the additional optical mode.

6. The method of claim 1 , wherein the generating an aggregated defect profile based on the two or more inspection images from the two or more locations for the first optical mode for a selected defect type comprises:
generating an averaged defect profile based on the two or more inspection images from the two or more locations for the first optical mode for a selected defect type.

7. The method of claim 1 , wherein the calculating one or more noise correlation characteristics of the two or more inspection images acquired from the two or more locations for the first optical mode comprises:
calculating one or more noise correlation matrices of the two or more inspection images acquired from the two or more locations for the first optical mode.

8. The method of claim 1 , wherein the acquiring two or more inspection images from a sample from two or more locations of the sample for a first optical mode comprises:
acquiring two or more inspection images from a sample from two or more locations of the sample for a first optical mode via a darkfield inspection process.

9. The method of claim 1 , wherein the acquiring two or more inspection images from a sample from two or more locations of the sample for a first optical mode comprises:
acquiring two or more inspection images from a sample from two or more locations of the sample for a first optical mode via a brightfield inspection process.

10. A system comprising:
an inspection sub-system including an illumination source configured to direct illumination onto one or more selected portions of a sample and one or more detectors configured to acquire two or more inspection images from the sample from two or more locations of the sample for a first optical mode; and
a controller communicatively coupled to the one or more detectors, the controller including one or more processors configured to execute program instructed configured to cause the one or more processors to:
receive the two or more inspection images acquired from the two or more locations from the one or more detectors for the first optical mode;
generate an aggregated defect profile based on the two or more inspection images from the two or more locations received from the one or more detectors for the first optical mode for a selected defect type;
calculate one or more noise correlation characteristics of the two or more inspection images acquired from the two or more locations for the first optical mode; and
generate a matched filter for the first optical mode based on the generated aggregated defect profile and the calculated one or more noise correlation characteristics.

11. The system of claim 10 , wherein the one or more processors are further configured to:
apply the generated matched filter to an acquired inspection image for the first optical mode to form a first filtered image.

12. The system of claim 11 , wherein the one or more processors are further configured to:
convolve the generated matched filter with an acquired inspection image for the first optical mode.

13. The system of claim 11 , wherein the one or more processors are further configured to:
acquire two or more inspection images from the sample from two or more locations of the sample for an additional optical mode;
generate an additional aggregated defect profile based on the two or more inspection images from the two or more locations for the additional optical mode for a selected defect type;
calculate one or more additional noise correlation characteristics of the two or more inspection images acquired from the two or more locations for the additional optical mode;
generate an additional matched filter for the additional optical mode based on the generated additional aggregated defect profile and the calculated one or more additional noise correlation characteristics; and
apply the additional generated matched filter to at least one of the two or more acquired inspection images for the additional optical mode to form an additional filtered image.

14. The system of claim 13 , wherein the one or more processors are further configured to:
compare the first filtered image to the additional filtered image to rank the first optical mode and the additional optical mode.

15. The system of claim 10 , wherein the generating an aggregated defect profile based on the two or more inspection images from the two or more locations for the first optical mode for a selected defect type comprises:
generating an averaged defect profile based on the two or more inspection images from the two or more locations for the first optical mode for a selected defect type.

16. The system of claim 10 , wherein the calculating one or more noise correlation characteristics of the two or more inspection images acquired from the two or more locations for the first optical mode comprises:
calculating one or more noise correlation matrices of the two or more inspection images acquired from the two or more locations for the first optical mode.

17. The system of claim 10 , wherein generated matched filter comprises:
a non-symmetric matched filter.

18. The system of claim 10 , wherein generated matched filter comprises:
a left-right-symmetric matched filter.

19. The system of claim 10 , further comprising:
one or more display devices.

20. The system of cl

Assignees

• Kla Tencor Corp

Inventors

• Kolchin Pavel
• Shifrin Eugene

Classifications

• G06V10/30

  Noise filtering · CPC title

• G06V10/751

  Comparing pixel values or logical combinations thereof, or feature values having positional relevance, e.g. template matching · CPC title

• G06V10/147

  Details of sensors, e.g. sensor lenses (fingerprint or palmprint sensors G06V40/13; vascular sensors G06V40/145; eye sensors G06V40/19) · CPC title

• G06T2207/10056

  Microscopic image · CPC title

• G06T5/002

  Physics · mapped topic