Methods for accurate identification of an edge of a care area for an array area formed on a wafer and methods for binning defects detected in an array area formed on a wafer

• US 8,213,705 B2
• Filed: 02/22/2011
• Issued: 07/03/2012
• Est. Priority Date: 02/28/2007
• Status: Active Grant

• Current Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Original Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Inventors: Chen, Chien-Huei (Adam), Wang, Xiaoming, Shifrin, Eugene, Fang, Tsung-Pao
• Primary Examiner(s): Werner, Brian P
• Application Number:
  US13/032,577
• Publication Number:
  US 20110142327A1
• Time in Patent Office: 497 Days
• Field of Search: None
• US Class Current: 382/149
• CPC Class Codes: G06T 2207/10056 Microscopic image
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/001 using an image reference approach
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06T 7/187 involving region growing; involving region merging; involving connected component labelling

Abstract

Methods for identifying an edge of a care area for an array area formed on a wafer and/or for binning defects detected in the array area are provided. One method for identifying an edge of a care area for an array area formed on a wafer includes determining a value for a difference image as a function of position from a position known to be inside the array area to a position known to be outside of the array area. The method also includes identifying the position that is located closest to the inside of the array area and that has the value greater than a threshold as a position of the edge of the care area.

Claims

1. A computer-implemented method for binning defects detected in an array area formed on a wafer, comprising:

identifying an edge of a care area for the array area, wherein said identifying comprises determining a value for a difference image as a function of position from a position known to be inside the array area to a position known to be outside of the array area, determining a threshold from an average of the values for the difference image known to be inside the array area, and identifying the position that is located closest to the inside of the array area and that has the value greater than the threshold as a position of the edge of the care area;

determining distances between positions of the defects and the edge of the array area; and

binning the defects in groups such that the distances determined for the defects in each of the groups are at least similar, wherein said identifying, said determining, and said binning are performed using a computer system.

2. The method of claim 1, wherein the distances comprise distances in an x direction and a y direction, and wherein said binning comprises binning the defects in the groups such that the distances in the x direction determined for the defects in each of the groups are at least similar and such that the distances in the y direction determined for the defects in each of the groups are at least similar.

3. The method of claim 1, further comprising selecting the distances associated with each of the groups such that said binning comprises binning the defects into the groups such that each of the groups includes only nuisance defects or only defects of interest.

4. The method of claim 1, wherein identifying the position comprises expanding an original care area in x.

5. The method of claim 1, wherein the edge of the care area is a left edge of the care area, and wherein the method further comprises performing said determining the value and said identifying the position to identify a right edge of the care area.

6. The method of claim 1, wherein identifying the position comprises expanding an original care area in x, and wherein the method further comprises expanding the original care area in y.

7. The method of claim 1, wherein all steps of the method are performed during runtime of inspection of the wafer.

8. The method of claim 1, further comprising detecting defects in the array area by performing cell-to-cell comparisons in the care area.

9. The method of claim 1, further comprising performing said identifying the edge of the care area for multiple array areas on the wafer on an individual array area basis.

10. The method of claim 1, wherein said identifying the edge further comprises determining if a repeating pattern is formed at each of the positions and identifying the position that is located closest to the inside of the array area, that has the value greater than the threshold, and at which the repeating pattern is formed as the position of the edge of the care area.

11. The method of claim 10, wherein said identifying the position comprises expanding an original care area in y.

12. The method of claim 10, wherein the edge of the care area is a top edge of the care area, and wherein the method further comprises performing determining the value, said determining if the repeating pattern is formed at each of the positions, and said identifying the position to identify a bottom edge of the care area.

13. The method of claim 10, wherein said identifying the position comprises expanding an original care area in y, and wherein the method further comprises expanding the original care area in x.

14. The method of claim 10, wherein said determining if the repeating pattern is formed at each of the positions is performed using a pattern recognition technique.

15. The method of claim 10, wherein said determining if the repeating pattern is formed at each of the positions is performed using a template matching technique.

16. The method of claim 10, wherein all steps of the method are performed during runtime of inspection of the wafer.

17. The method of claim 10, further comprising detecting defects in the array area by performing cell-to-cell comparisons in the care area.

18. The method of claim 10, further comprising performing said identifying the edge of the care area for multiple array areas on the wafer on an individual array area basis.

19. A non-transitory computer-readable medium comprising program instructions executable on a computer system for performing a computer-implemented method for binning defects detected in an array area formed on a wafer, wherein the computer-implemented method comprises:

identifying an edge of a care area for the array area, wherein said identifying comprises determining a value for a difference image as a function of position from a position known to be inside the array area to a position known to be outside of the array area, determining a threshold from an average of the values for the difference image known to be inside the array area, and identifying the position that is located closest to the inside of the array area and that has the value greater than the threshold as a position of the edge of the care area;

determining distances between positions of the defects and the edge of the array area; and

binning the defects in groups such that the distances determined for the defects in each of the groups are at least similar.

20. A system configured to bin defects detected in an array area formed on a wafer comprising:

an inspection subsystem configured to acquire images of the wafer; and

a computer subsystem configured to detect the defects in the array area formed on the wafer using the images, to identify an edge of a care area for the array area by determining a value for a difference image as a function of position from a position known to be inside the array area to a position known to be outside of the array area, determining a threshold from an average of the values for the difference image known to be inside the array area, and identifying the position that is located closest to the inside of the array area and that has the value greater than the threshold as a position of the edge of the care area, and to bin the defects detected in the array area by determining distances between positions of the defects and the edge of the array area and binning the defects in groups such that the distances determined for the defects in each of the groups are at least similar.