System and method for determining type and size of defects on blank reticles

Patent metadata

Field	Value
Publication number	US-11468553-B2
Application number	US-201916572971-A
Country	US
Kind code	B2
Filing date	Sep 17, 2019
Priority date	Nov 2, 2018
Publication date	Oct 11, 2022
Grant date	Oct 11, 2022

Abstract

A system for characterizing a specimen is disclosed. In one embodiment, the system includes a controller configured to: receive training images of one or more defects of the specimen; generate a machine learning classifier based on the training images; receive product images of one or more defects of a specimen; determine one or more defect type classifications of one or more defects with the machine learning classifier; filter the product images with one or more smoothing filters; perform binarization processes to generate binarized product images; perform morphological image processing operations on the binarized product images; determine one or more algorithm-estimated defect sizes of the one or more defects based on the binarized product images; and determine one or more refined estimates of one or more defect sizes of the one or more defects based on the one or more algorithm-estimated defect sizes and the one or more defect type classifications.

First claim

What is claimed:

1. A system for characterizing a specimen, comprising:
a controller including one or more processors configured to execute a set of program instructions stored in memory, the set of program instructions configured to cause the one or more processors to:
receive one or more training images of one or more defects of the specimen, wherein the one or more training images include a set of patch images for defects ranging from 80 to 200 nm and a set of review images for defects larger than 200 nm;
generate one or more machine learning classifiers based on the one or more training images;
receive one or more product images of one or more defects of a specimen, wherein some of the one or more product images are patch images and some of the one or more product images are review images;
determine one or more defect type classifications of the one or more defects with the one or more machine learning classifiers;
filter the one or more product images with one or more smoothing filters;
perform one or more binarization processes to generate one or more binarized product images;
perform one or more morphological image processing operations on the one or more binarized product images;
determine one or more defect sizes for product images having defect sizes between 80 and 200 nm using patch images and determine one or more defect sizes for product images having defect sizes above 200 nm using review images; and
determine one or more refined estimates of one or more defect sizes of the one or more defects having a size smaller than 80 nm based on one or more algorithm-estimated defect sizes and the one or more defect type classifications.

2. The system of claim 1 , wherein the one or more defect type classifications comprise at least one of a pin-hole defect classification, a resist-dot defect classification, a scratch defect classification, or a fast localized defect classification.

3. The system of claim 1 , wherein receiving the one or more training images of one or more defects of the specimen comprises:
receiving the one or more training images of the one or more defects of the specimen; and
receiving at least one of a known defect type classification or a known defect size associated with the one or more defects.

4. The system of claim 1 , wherein the machine learning classifier comprises at least one of a random forest classifier, a support vector machine (SVM) classifier, an ensemble learning classifier, or a deep neural network.

5. The system of claim 1 , further comprising an inspection sub-system, wherein at least one of the one or more training images or the one or more product images are received from the inspection sub-system.

6. The system of claim 1 , wherein the controller is further configured to:
perform one or more image processing operations on the one or more product images.

7. The system of claim 6 , wherein performing the one or more image processing operations comprises:
adjusting a size of the one or more product images with an image scaling operation to generate one or more scaled product images; and
altering the one or more scaled product images with one or more image sharpening operations.

8. The system of claim 7 , wherein the one or more image scaling operations comprise an image upscaling operation.

9. The system of claim 7 , wherein the one or more image sharpening operations comprise:
an image filtering operation performed with a Laplacian filter.

10. The system of claim 6 , wherein performing the one or more image processing operations on the one or more product images comprises:
converting the one or more product images from a first color space system to a second color space system.

11. The system of claim 10 , wherein the first color space system comprises a red-green-blue (RGB) color space system, and the second color space system comprises a hue-saturation-value (HSV) color space system.

12. The system of claim 1 , wherein the controller is further configured to:
identify a plurality of pixel clusters within the one or more binarized product images; and
determine one or more pixel clusters of the plurality of pixel clusters to be associated with the one or more defects.

13. The system of claim 1 , wherein the one or more morphological image processing operations comprise at least one of a morphological erosion operation, a morphological dilation operation, a morphological opening operation, or a morphological closing operation.

14. The system of claim 1 , wherein the specimen comprises a reticle.

15. The system of claim 1 , wherein the controller is configured to generate one or more control signals based on at least one of the one or more refined estimates or the one or more defect type classifications, the one or more control signals configured to selectively adjust one or more process tools.

16. The system of claim 1 , wherein the controller is further configured to:
generate one or more mathematical models configured to correlate the one or more algorithm-estimated defect sizes to one or more known defect sizes of the one or more defects within the one or more training images.

17. The system of claim 16 , wherein determining the one or more refined estimates of the one or more defect sizes of the one or more defects based on the one or more algorithm-estimated defect sizes and the one or more defect type classifications comprises:
determining the one or more refined estimates of the one or more defect sizes of the one or more defects based at least in part on the one or more generated mathematical models.

18. A system for characterizing a specimen, comprising:
an inspection sub-system configured to acquire one or more images of a specimen; and
a controller communicatively coupled to the inspection sub-system, the controller including one or more processors configured to execute a set of program instructions stored in memory, the set of program instructions configured to cause the one or more processors to:
receive one or more training images of one or more defects of the specimen from the inspection sub-system, wherein the one or more training images include a set of patch images for defects ranging from 80 to 200 nm and a set of review images for defects larger than 200 nm;
generate one or more machine learning classifiers based on the one or more training images;
receive one or more product images of one or more defects of a specimen from the inspection sub-system, wherein some of the one or more product images are patch images and some of the one or more product images are review images;
determine one or more defect type classifications of the one or more defects of the product images with the one or more machine learning classifiers;
perform one or more morphological image processing operations on the one or more product images;
determine one or more defect sizes for product images having defect sizes between 80 and 200 nm using patch images and determine one or more defect sizes for product images having defect sizes above 200 nm using review images; and
determine one or more refined estimates of one or more defect sizes of the one or more defects having a size smaller than 80 nm based on one or more algorithm-estimated defect sizes and the one or more defect type classifications.

19. The system of claim 18 , wherein the controller is further configured to:
generate one or more mathematical models configured to correlate the one or more algorithm-estimated defect sizes to one or more known defect sizes of the one or more defects within the on

Assignees

• Kla Corp

Inventors

• Kulkarni Ramaprasad
• Cong Ge
• Fang Hawren

Classifications

• G06V20/69

  Microscopic objects, e.g. biological cells or cellular parts · CPC title

• G06V10/776

  Validation; Performance evaluation · CPC title

• G06N5/01

  Dynamic search techniques; Heuristics; Dynamic trees; Branch-and-bound · CPC title

• G06N3/045

  Combinations of networks · CPC title

• G06F18/2431

  Multiple classes · CPC title