Imaging of crystalline defects

Patent metadata

Field	Value
Publication number	US-10347462-B2
Application number	US-201815955467-A
Country	US
Kind code	B2
Filing date	Apr 17, 2018
Priority date	Dec 11, 2017
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A method for detecting crystal defects includes scanning a first FOV on a first sample using a charged particle beam with a plurality of different tilt angles. BSE emitted from the first sample are detected and a first image of the first FOV is created. A first area within the first image is identified where signals from the BSE are lower than other areas of the first image. A second FOV on a second sample is scanned using approximately the same tilt angles or deflections as those used to scan the first area. The BSE emitted from the second sample are detected and a second image of the second FOV is created. Crystal defects within the second sample are identified by identifying areas within the second image where signals from the BSE are different than other areas of the second image.

First claim

What is claimed is:

1. A method for detecting defects in a crystalline material using a charged particle beam apparatus, the method comprising:
scanning a first sample of the crystalline material using a charged particle beam, wherein:
the charged particle beam has a beam energy of at least 2 kV,
a first field of view (FOV) of the charged particle beam covers an area of at least 50 μm by 50 μm on the first sample of the crystalline material,
the charged particle beam has approximately zero tilt at a center of the first FOV, and
the charged particle beam has an increasing tilt angle with distance from the center of the first FOV;

detecting backscattered electrons (BSE) emitted from the first sample of the crystalline material using one or more detectors of the charged particle beam apparatus;
creating a first image of the first FOV based on the detected BSE;
identifying a first area within the first image where signals from the BSE are lower than other areas of the first image; and thereafter
scanning a second sample of the crystalline material using the charged particle beam, the second sample having a crystalline orientation relative to the charged particle beam apparatus that is substantially the same as the first sample, wherein:
the charged particle beam has the beam energy of at least 2 kV,
a second FOV of the charged particle beam covers an area of no more than 50 μm by 50 μm on the second sample of the crystalline material, and
the charged particle beam has approximately the same tilt angles or deflections as those used to scan the first area,

detecting the BSE emitted from the second sample of the crystalline material using the one or more detectors of the charged particle beam apparatus;
creating a second image of the second FOV based on the detected BSE; and
identifying crystal defects within the second sample of the crystalline material by identifying areas within the second image where signals from the BSE are different than other areas of the second image.

2. The method of claim 1 wherein the first image includes multiple areas where signals from the BSE are lower than other areas of the first image, and identifying the first area within the first image includes identifying an area where signals from the BSE are lower than any other areas of the first image.

3. The method of claim 1 wherein tilt angles of the charged particle beam are changed electronically while scanning the first FOV and while scanning the second FOV.

4. The method of claim 1 wherein identifying the first area within the first image includes identifying an area within the first image that is darker than other areas of the first image.

5. The method of claim 1 wherein the first sample of the crystalline material and the second sample of the crystalline material are stationary relative to the charged particle beam apparatus during scanning.

6. A method for detecting defects in a crystalline material using a charged particle beam apparatus, the method comprising:
scanning a first sample of the crystalline material using a charged particle beam, wherein a first field of view (FOV) of the charged particle beam covers an area on the first sample of the crystalline material, and a plurality of different tilt angles of the charged particle beam are used to scan the first FOV;
detecting backscattered electrons (BSE) emitted from the first sample of the crystalline material using one or more detectors of the charged particle beam apparatus;
creating a first image of the first FOV based on the detected BSE;
identifying a first area within the first image where signals from the BSE are lower than other areas of the first image; and thereafter
scanning a second sample of the crystalline material using the charged particle beam, the second sample having a crystalline orientation relative to the charged particle beam apparatus that is substantially the same as the first sample, wherein a second FOV of the charged particle beam covers an area on the second sample of the crystalline material that is smaller than the first FOV, and the charged particle beam has approximately the same tilt angles or deflections as those used to scan the first area;
detecting the BSE emitted from the second sample of the crystalline material using the one or more detectors of the charged particle beam apparatus;
creating a second image of the second FOV based on the detected BSE; and
identifying crystal defects within the second sample of the crystalline material by identifying areas within the second image where signals from the BSE are different than other areas of the second image.

7. The method of claim 6 wherein the charged particle beam has a beam energy of at least 2 kV.

8. The method of claim 6 wherein the area of the first FOV on the first sample of the crystalline material is at least 100 μm by 100 μm, and the area of the second FOV on the second sample of the crystalline material is no more than 50 μm by 50 μm.

9. The method of claim 6 wherein the charged particle beam has an approximately zero tilt at a center of the first FOV, and the charged particle beam has an increasing tilt angle with distance from the center of the first FOV.

10. The method of claim 6 wherein the first image includes multiple areas where signals from the BSE are lower than other areas of the first image, and identifying the first area within the first image includes identifying an area where signals from the BSE are lower than any other areas of the first image.

11. The method of claim 6 wherein tilt angles of the charged particle beam are changed electronically while scanning the first FOV and while scanning the second FOV.

12. The method of claim 6 wherein identifying the first area within the first image includes identifying an area within the first image that is darker than other areas of the first image.

13. A nontransitory computer-readable medium storing instructions that, when executed by one or more processors of a charged particle beam apparatus, cause the charged particle beam apparatus to perform operations comprising:
scanning a first sample of crystalline material using a charged particle beam, wherein a first field of view (FOV) of the charged particle beam covers an area on the first sample of the crystalline material, and a plurality of different tilt angles of the charged particle beam are used to scan the first FOV;
detecting backscattered electrons (BSE) emitted from the first sample of the crystalline material using one or more detectors of the charged particle beam apparatus;
creating a first image of the first FOV based on the detected BSE;
scanning a second sample of the crystalline material using the charged particle beam, wherein a second FOV of the charged particle beam covers an area on the second sample of the crystalline material, and the charged particle beam has the same tilt angles or deflections as those used to scan a first area within the first image where signals from the BSE are lower than other areas of the first image;
detecting the BSE emitted from the second sample of the crystalline material using the one or more detectors of the charged particle beam apparatus; and
creating a second image of the second FOV based on the detected BSE.

14. The nontransitory computer-readable medium of claim 13 further comprising instructions that, when executed by the one or more processors, cause the charged particle beam apparatus to perform operations comprising:
identifying the first area within the first image using an image processing technique; and
determining the tilt angles or deflections of the charged particle beam used to scan

Assignees

• Applied Materials Israel Ltd

Inventors

• Shemesh Dror
• Lev Uri
• Colombeau Benjamin
• Wachs Amir
• Nafisi Kourosh

Classifications

• H01J2237/221

  Image processing · CPC title

• G01N2223/6462

  microdefects · CPC title

• H01J37/244

  Detectors; Associated components or circuits therefor · CPC title

• H01J2237/24475

  Scattered electron detectors · CPC title

• G01N2223/418

  electron microscope · CPC title