Defect observation system and defect observation method for semiconductor wafer

Patent metadata

Field	Value
Publication number	US-10971325-B2
Application number	US-201916567687-A
Country	US
Kind code	B2
Filing date	Sep 11, 2019
Priority date	Sep 12, 2018
Publication date	Apr 6, 2021
Grant date	Apr 6, 2021

Abstract

In a device for observing a semiconductor wafer, a positional relationship between an in-wafer region and a background region in an imaging field of view is not constant when an outer peripheral portion of the wafer is imaged, which results in an increase in the quantity of calculation in defect detection and image classification processing and makes it difficult to efficiently perform defect observation and analysis. There is provided a defect observation system for a semiconductor wafer, and the system includes: a stage on which the semiconductor wafer is placed and which is movable in an XY direction, an imaging unit that is configured to image a portion including an edge of the semiconductor wafer, and an image output unit that is configured to, with respect to a plurality of images obtained by imaging, output images in which edges of the wafer are substantially in parallel among the plurality of images.

First claim

What is claimed is:

1. A defect observation system for a semiconductor wafer, comprising:
a stage on which the semiconductor wafer is placed and which is movable in an XY direction; and
a processor configured to control an electron source which irradiates the semiconductor wafer with an electron beam to obtain a plurality of images each having a portion including an edge of the semiconductor wafer, each said image being obtained while moving the semiconductor wafer in an XY direction on a plane,
wherein the processor is further configured to, with respect to said plurality of obtained images, output a plurality of selected images which are selected from among said plurality of obtained images and in which edges of the semiconductor wafer are substantially in parallel, and to detect a defect of the semiconductor wafer in the output images in which edges of the semiconductor wafer are substantially parallel.

2. The defect observation system according to claim 1 ,
wherein the processor is further configured to, with respect to the plurality selected images, control a deflector to rotate a scan direction of the electron beam emitted by the electron source with respect to the selected images so as to make the edges of the semiconductor wafer substantially in parallel in the plurality of selected images.

3. The defect observation system according to claim 2 , wherein the processor is further configured to
detect a defect of the semiconductor wafer in the output plurality of selected images, and
classify the output plurality of selected images
based on a stored rotation angle of the image, said stored rotation angle being stored as supplementary information for each said output image, as a feature amount for image classification associated with each said output image.

4. The defect observation system according to claim 1 ,
wherein the processor is further configured to, with respect to the plurality of selected images, control a deflector to rotate a scan direction of the electron beam emitted by the electron source with respect to the selected images such that the edges of the semiconductor wafer are substantially in parallel, and to move the plurality of selected images in parallel such that the edges of the semiconductor wafer are substantially at a same position, so that the edges of the semiconductor wafer are substantially at the same position in the plurality of images.

5. The defect observation system according to claim 1 ,
wherein the processor is further configured to rotate a scan direction of the electron beam by controlling a deflector so as to make the edges of the semiconductor wafer substantially in parallel in the plurality of selected images, and
wherein the defect observation system is a charged particle microscope.

6. The defect observation system according to claim 5 ,
wherein the processor is further configured to adjust a scan direction of the electron beam so as to make the edges of the semiconductor wafer substantially in parallel in the plurality of selected images,
wherein the processor is further configured to, with respect to the plurality of selected images in which the edges of the semiconductor wafer are substantially parallel, move the images in parallel so as to make the edges of the semiconductor wafer substantially at a same position in the plurality of selected images, and
wherein defect observation system is a charged particle microscope.

7. The defect observation system according to claim 5 ,
wherein the processor is further configured to adjust a scan direction by controlling a deflection angle of the electron beam so as to make the edges of the semiconductor wafer substantially at a same position in the plurality of selected images, and
wherein the defect observation system is a charged particle microscope.

8. The defect observation system according to claim 5 , wherein the processor is further configured to
detect a defect of the semiconductor wafer in the output plurality of selected images, and
classify the output plurality of selected images
based on a stored deflection angle of the electron beam which is stored as supplementary information for each said output image, as a feature amount for image classification associated with each said output image.

9. The defect observation system according to claim 1 ,
wherein the processor is further configured to output the plurality of selected images in which the edges of the semiconductor wafer are substantially in parallel or substantially at a same position in the plurality of obtained images.

10. The defect observation system according to claim 1 , wherein the processor is further configured to
detect a defect of the semiconductor wafer in the output plurality of selected images and
classify the output plurality of selected images based on stored position information associated with each said selected image, said stored position information indicating a positional relationship between a background region and an in-wafer region for each of the output images.

11. A defect observation method for a semiconductor wafer, comprising:
an imaging step of imaging a plurality of portions including an edge of the semiconductor wafer while moving the semiconductor wafer in an XY direction on a plane;
an output step of, with respect to a plurality of images obtained by imaging, outputting images in which edges of the semiconductor wafer are substantially in parallel among the plurality of images; and
a defect detection step of detecting a defect of the semiconductor wafer in the output images.

12. The defect observation method according to claim 11 , wherein in the image output step, the images in which the edges of the semiconductor wafer are substantially at the same position in the plurality of images are output.

13. The defect observation method according to claim 11 , further comprising:
a classification step of classifying the output images by adjusting a scan rotation angle of the output images so that the edges of the semiconductor device are aligned in one direction for each of the output images and a positional relationship between a background region and an in-wafer region is the same for each of the output images.

14. A non-transitory computer-readable medium upon which is embodied a sequence of programmed instructions which, when executed by a processor, cause the processor to perform the following:
an imaging step of imaging a plurality of portions including an edge of the semiconductor wafer while moving the semiconductor wafer in an XY direction on a plane;
an output step of, with respect to a plurality of images obtained by imaging, outputting images in which edges of the semiconductor wafer are substantially in parallel among the plurality of images; and
a defect detection step of detecting a defect of the semiconductor wafer in the output images.

15. The non-transitory computer-readable medium according to claim 14 , wherein in the image output step, the images in which the edges of the semiconductor wafer are substantially at the same position in the plurality of images are output.

16. The non-transitory computer-readable medium according to claim 14 , wherein the instructions further comprise:
a classification step of classifying the output images by adjusting a scan rotation angle of the output images so that the edges of the semiconductor device are aligned in one direction for each of the output images and a positional relationship between a background region and an in-wafer region is the same for each of the output images.

Assignees

• Hitachi High Tech Corp

Inventors

• Harada Minoru
• Takagi Yuji
• Kondo Naoaki
• Hirai Takehiro
• Minekawa Yohei

Classifications

• H10P72/0616

  Monitoring of warpages, curvatures, damages, defects or the like · CPC title

• G06T2207/30148

  Semiconductor; IC; Wafer · CPC title

• H01J37/222

  Image processing arrangements associated with the tube · CPC title

• G06T2207/10061

  from scanning electron microscope · CPC title

• H01J2237/2817

  Pattern inspection · CPC title