Defect observation device and defect observation method
View Patent ↗In a scheme for analyzing low magnification defect images and determining whether or not a defect detection method using cell comparison is applicable, if a defect detection method using cell comparison cannot be applied and the proportion transitioning to a defect detection method using die comparison increases, throughput may decrease even more than starting out with defect detection by a defect detection method using die comparison. The purpose of present invention is to carry out high precision defect detection with a stable throughput. In the present invention, the defect detection processing mode applied for detecting defects from the defect image is determined using a reference image, and defects are detected from the defect image by the defect detection processing mode that has been determined.
1. A defect observation device comprising:
a charged particle optical system that detects secondary particles obtained by irradiating a sample with a charged particle beam;
an image processing unit that generates an image by using signals based on the secondary particles, and analyzes the image; and
a stage that holds and moves the sample,
wherein the image processing unit includes
an image generation portion that generates a defect image which is an image of a region including coordinates of defect candidates, and a reference image which is an image including a region in which a pattern having the same shape as a shape of a pattern included in the defect image is formed in a die which is different from a die in which the defect image is acquired,
a mode determination processing portion that determines a defect detection processing mode appropriate for detecting a defect from the defect image by using the reference image, and
a defect detection processing portion that detects a defect from the defect image in the defect detection processing mode determined by the mode determination processing portion.
2. The defect observation device according to claim 1 ,
wherein the defect detection processing mode includes a defect detection mode using cell comparison in which a defect is detected by comparing repeated patterns in the defect image with each other, and a defect detection mode using die comparison in which a defect is detected by comparing the defect image with the reference image.
3. The defect observation device according to claim 2 ,
wherein the image processing unit combines a result detected in the defect detection mode using cell comparison with a result detected in the defect detection mode using die comparison so as to fix a final defect detection result.
4. The defect observation device according to claim 2 ,
wherein the image processing unit determines a difference between a synthesized image which is synthesized on the basis of the repeated patterns in the defect image and the reference image as a noise component in the defect detection mode using cell comparison.
5. The defect observation device according to claim 1 ,
wherein an image of a position detected by the defect detection processing portion is acquired again without moving the stage after the defect image is acquired.
6. The defect observation device according to claim 1 ,
wherein parameters used for a process of detecting the defect can be set to correspond to the defect detection mode determined by the mode determination processing portion.
7. The defect observation device according to claim 1 ,
wherein the reference image is acquired at positions where the coordinates of the defect candidates are projected onto a predetermined die which is designated in advance.
8. The defect observation device according to claim 1 ,
wherein the mode determination processing portion determines a defect detection processing mode according to the presence or absence of a pre-registered pattern in the reference image.
9. The defect observation device according to claim 8 ,
wherein, in a case where the registered pattern is present, a position detected by the defect detection processing portion is not imaged again.
10. The defect observation device according to claim 8 ,
wherein, in a case where the registered pattern is present, an image of a partial region is cut out of the defect image, and an image having a magnification higher than a magnification of the defect image is generated by performing a digital zoom process on the cutout image.
11. A defect observation method of detecting secondary particles obtained by irradiating a sample with a charged particle beam, and generating an image by using signals based on the secondary particles, the method comprising:
acquiring a defect image which is an image of a region including coordinates of defect candidates, and a reference image which is an image including a region in which a pattern having the same shape as a shape of a pattern included in the defect image is formed in a die which is different from a die in which the defect image is acquired;
determining a defect detection processing mode appropriate for detecting a defect from the defect image by using the reference image; and
detecting a defect from the defect image in the determined defect detection processing mode.
12. The defect observation method according to claim 11 ,
wherein the defect detection processing mode includes a defect detection mode using cell comparison in which a defect is detected by comparing repeated patterns in the defect image with each other, and a defect detection mode using die comparison in which a defect is detected by comparing the defect image with the reference image.
13. The defect observation method according to claim 12 ,
wherein a result detected in the defect detection mode using cell comparison is combined with a result detected in the defect detection mode using die comparison, and thus a final defect detection result is fixed.
14. The defect observation method according to claim 12 ,
wherein a difference between a synthesized image which is synthesized on the basis of the repeated patterns in the defect image and the reference image is determined as a noise component in the defect detection mode using cell comparison.
15. The defect observation method according to claim 11 ,
wherein an image of a position detected by the defect detection processing portion is acquired again without moving the stage after the defect image is acquired.
16. The defect observation method according to claim 11 ,
wherein parameters used for a process of detecting the defect can be set to correspond to the determined defect detection mode.
17. The defect observation method according to claim 11 ,
wherein the reference image is acquired at positions where the coordinates of the defect candidates are projected onto a predetermined die which is designated in advance.
18. The defect observation method according to claim 11 ,
wherein a defect detection processing mode is determined according to the presence or absence of a pre-registered pattern in the reference image.
19. The defect observation method according to claim 18 ,
wherein, in a case where the registered pattern is present, a position of the detected defect is not imaged again.
20. The defect observation method according to claim 18 ,
wherein, in a case where the registered pattern is present, an image of a partial region is cut out of the defect image, and an image having a magnification higher than a magnification of the defect image is generated by performing a digital zoom process on the cutout image.