Computer-implemented methods for detecting and/or sorting defects in a design pattern of a reticle

• US 8,111,900 B2
• Filed: 05/15/2010
• Issued: 02/07/2012
• Est. Priority Date: 12/07/2004
• Status: Active Grant

• Current Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Original Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Inventors: Wu, Kenong, Randall, David, Nafisi, Kourosh, Ynzunza, Ramon, Peterson, Ingrid B., Tribble, Ariel, Kowalski, Michal, Gao, Lisheng, Kulkarni, Ashok
• Primary Examiner(s): Bali, Vikkram
• Assistant Examiner(s): Entezari, Michelle
• Application Number:
  US12/780,864
• Publication Number:
  US 20100226562A1
• Time in Patent Office: 633 Days
• Field of Search: 382/149
• US Class Current: 382/144
• CPC Class Codes: G01N 2021/95676 Masks, reticles, shadow masks
• CPC Class Codes: G01N 21/95607 using a comparative method
• CPC Class Codes: G03F 1/84 Inspecting
• CPC Class Codes: G03F 7/7065 Defects, e.g. optical inspection of patterned layer for defects
• CPC Class Codes: G03F 7/70666 Aerial image, i.e. measuring the image of the patterned exposure light at the image plane of the projection system

Abstract

Various computer-implemented methods are provided. One method for sorting defects in a design pattern of a reticle includes searching for defects of interest in inspection data using priority information associated with individual defects in combination with one or more characteristics of a region proximate the individual defects. The priority information corresponds to modulation levels associated with the individual defects. The inspection data is generated by comparing images of the reticle generated for different values of a lithographic variable. The images include at least one reference image and at least one modulated image. A composite reference image can be generated from two or more reference images. The method also includes assigning one or more identifiers to the defects of interest. The identifier(s) may include, for example, a defect classification and/or an indicator identifying if the defects of interest are to be used for further processing.

Claims

1. A computer-implemented method for detecting defects in a design pattern of a reticle, comprising:

acquiring images of the reticle for different values of a lithographic variable, wherein the images comprise two or more reference images obtained at nominal values and one or more modulated images;

generating a composite reference image from the two or more reference images, wherein the composite reference image comprises image data that is different than image data of the two or more reference images, and wherein the composite reference image does not comprise defects;

comparing at least two of the images, wherein the at least two of the images comprise the composite reference image; and

determining if a detect is present in the design pattern using results of said comparing.

2. The method of claim 1, wherein if the defect is determined to be present, the method further comprises assigning the defect to a group based on one or more characteristics of a region proximate the defect.

3. The method of claim 2, wherein the one or more characteristics of the region comprise one or more characteristics of the design pattern in the region of at least one of the two or more reference images.

4. The method of claim 2, wherein the one or more characteristics of the region comprise one or more characteristics of the region in the at least two of the images used for said comparing.

5. The method of claim 2, wherein the one or more characteristics of the region comprise one or more characteristics of the region extracted from a GDS or aerial image.

6. The method of claim 2, wherein the one or more characteristics of the region comprise one or more characteristics of the region determined from a high resolution image.

7. The method of claim 2, further comprising analyzing the one or more characteristics of the region of one or more defects in the group to determine if the group is an irrelevant defect group.

8. The method of claim 2, further comprising analyzing one or more characteristics of one or more defects in the group to determine if the group indicates a failure in the design pattern.

9. The method of claim 1, wherein the images further comprise images of an entire swath of dies printed on a wafer using the reticle, and wherein the at least two of the images used for said comparing further comprise the images of all of the dies in the entire swath.

10. The method of claim 9, wherein modulated dies in the entire swath are printed using the same value of the lithographic variable, which is different than the value of the lithographic variable at which reference dies are printed in the entire swath.

11. The method of claim 9, wherein modulated dies in the entire swath are printed using the different values of the lithographic variable, and wherein reference dies in the entire swath are printed using an additional different value of the lithographic value.

12. The method of claim 1, wherein a user with knowledge of a layout of dies printed on a wafer selects which of the at least two of the images are used for said comparing.

13. The method of claim 1, wherein said acquiring comprises acquiring images of the design pattern printed on a wafer using the reticle.

14. A computer-implemented method for detecting defects in a design pattern of a reticle, comprising:

acquiring images of an entire swath of dies printed on a wafer using the reticle, wherein at least two of the dies are printed at different values of a lithographic variable, wherein the dies comprise modulated dies and two or more reference dies, and wherein a number of the modulated dies in the entire swath is greater than or equal to a number of the two or more reference dies in the entire swath;

generating a composite reference image from the images of the two or more reference dies, wherein the composite reference image does not comprise defects;

subsequent to said acquiring, comparing at least two of the images, wherein one of the at least two of the images used for said comparing comprises the composite reference image; and

determining if a defect is present in the design pattern using results of said comparing.

15. The method of claim 14, wherein the modulated dies are printed at values of the lithographic variable that are the same for each of the modulated dies but different than the value of the lithographic variable at which the two or more reference dies are printed.

16. The method of claim 14, wherein the modulated dies are printed at values of the lithographic variable that are different for each of the modulated dies and different than the value of the lithographic variable at which the two or more reference dies are printed.

17. A system configured to detect defects in a design pattern of a reticle, comprising:

an inspection tool configured to acquire images of the reticle for different values of a lithographic variable, wherein the images comprise two or more reference images obtained at nominal values and one or more modulated images;

a processor configured to receive the images; and

a storage medium comprising program instructions executable on the processor for performing a computer-implemented method, wherein the computer-implemented method comprises;

generating a composite reference image from the two or more reference images, wherein the composite reference image comprises image data that is different than image data of the two or more reference images, and wherein the composite reference image does not comprise defects;

comparing at least two of the images, wherein the at least two of the images comprise the composite reference image; and

determining if a defect is present in the design pattern using results of said comparing.