Charged particle beam system and method for determining observation conditions in charged particle beam device

Patent metadata

Field	Value
Publication number	US-12191111-B2
Application number	US-201917594656-A
Country	US
Kind code	B2
Filing date	May 8, 2019
Priority date	May 8, 2019
Publication date	Jan 7, 2025
Grant date	Jan 7, 2025

Abstract

The present disclosure provides a technique enabling accurate ascertaining of a charged state of a resist pattern resulting from irradiation of a charged particle beam. The present disclosure provides a charged particle beam system provided with: a charged particle device provided with a charged particle source, deflectors for causing a primary charged particle beam emitted from the charged particle source to be scanned over a sample, an energy discriminator for performing energy discrimination for secondary electrons emitted when the primary charged particle beam has reached the sample, and a detector for detecting secondary electrons which have passed the energy discriminator; and a computer system for generating a scan image on the basis of signal amounts detected by the detector, which fluctuate during scanning of primary charged particles by the deflectors, and storing the scan image into an image storage unit. The computer system generates a scan image for each frame at the time of frame integration of the scan image, calculates an amount of static build-up in each frame on the basis of the output of the scan image of each frame, and outputs information on the amount of static build-up.

First claim

The invention claimed is:

1. A charged particle beam system comprising:
a charged particle device including a charged particle source, a deflector that scans a primary charged particle beam emitted from the charged particle source on a sample, an energy discriminator that energy-discriminates a secondary electron emitted when the primary charged particle beam reaches the sample and a detector that detects the secondary electron that has passed through the energy discriminator; and
a computer system that generates a scan image based on a detection signal amount of the detector that fluctuates according to scanning of the primary charged particle beam by the deflector and stores the scan image in an image storage unit,
wherein the computer system generates a scan image for each frame of a plurality of frames obtained by the detector at the time of frame integration of the scan image, wherein the scan image for each frame is acquired by continuously scanning a specific portion of the sample with the primary charged particle beam, calculates a charging amount for each frame based on an output of the scan image for each frame, and outputs information on the charging amount.

2. The charged particle beam system according to claim 1 ,
wherein the computer system obtains a timing of static elimination based on information on the calculated charging amount for each frame and outputs information on the timing.

3. The charged particle beam system according to claim 2 ,
wherein the computer system determines the number of frames in which the charging amount for each frame exceeds a set allowable charging amount as a timing of performing the static elimination.

4. The charged particle beam system according to claim 1 ,
wherein the computer system determines a method for static elimination based on information on the calculated charging amount for each frame.

5. The charged particle beam system according to claim 4 ,
wherein the computer system determines the method for static elimination based on a polarity of the charging amount for each frame.

6. The charged particle beam system according to claim 3 ,
wherein the computer system calculates the charging amount for each frame based on the detection signal amount obtained by scanning the primary charged particle beam on the sample according to a plurality of types of set scanning conditions and determines and outputs optimum static elimination conditions corresponding to the plurality of types of the scanning conditions.

7. The charged particle beam system according to claim 6 ,
wherein the scanning conditions include information on a scanning speed and the number of frames acquired by scanning, and
wherein the plurality of types of the scanning conditions are set so that the scanning speed and the number of frames are different among the scanning conditions.

8. The charged particle beam system according to claim 7 ,
wherein the computer system outputs a scanning condition indicating the charging amount within the set allowable charging amount among a plurality of the charging amounts corresponding to the plurality of types of the scanning conditions as an optimum scanning condition.

9. The charged particle beam system according to claim 2 ,
wherein the computer system calculates the charging amount for each frame based on a scanned image for each frame obtained by scanning the primary charged particle beam on a plurality of measurement points on a test chip or a plurality of measurement points on the test chip and a measurement chip according to a plurality of types of set scanning conditions.

10. The charged particle beam system according to claim 9 ,
wherein the computer system calculates and outputs a change in the charging amount with respect to the measurement point according to the plurality of types of scanning conditions.

11. The charged particle beam system according to claim 10 ,
wherein the computer system calculates the static elimination timing corresponding to the plurality of types of the scanning conditions by comparing the change in the charging amount to the measurement point with a set allowable charging amount.

12. The charged particle beam system according to claim 11 ,
wherein the computer system controls the charged particle device so as to scan the primary charged particle beam on the measurement chip according to selected scanning conditions and to execute a static elimination operation at the static elimination timing corresponding to the selected scanning conditions.

13. The charged particle beam system according to claim 1 ,
wherein the energy discriminator is an energy filter or a spectrometer.

14. The charged particle beam system according to claim 1 ,
wherein the computer system generates the scan image by using different detection signal amounts for each number of frames, calculates the charging amount for each number of frames based on an output of the scan image for each number of frames, and outputs the information on the charging amount for each number of frames.

15. A charged particle beam system comprising:
a charged particle device including a charged particle source, a deflector that scans a primary charged particle beam emitted from the charged particle source on a sample, an energy discriminator that energy-discriminates a secondary electron emitted when the primary charged particle beam reaches the sample and a detector that detects the secondary electron that has passed through the energy discriminator; and
a computer system that generates a scan image for each frame of a plurality of frames obtained by the detector based on a detection signal amount of the detector that fluctuates according to scanning of the primary charged particle beam by the deflector and stores the scan image in an image storage unit, wherein the scan image for each frame is acquired by continuously scanning a specific portion of the sample with the primary charged particle beam,
wherein the computer system calculates a charging amount in the sample based on the scan images obtained corresponding to a plurality of types of scanning conditions, selects a scanning condition in which the charging amount is less than or equal to a predetermined value or a scanning condition which issues a minimum charging amount, and selects a static elimination method corresponding to the selected scanning condition.

16. A method for determining an observation condition in a charged particle beam device, comprising:
detecting a secondary electron by a detector by energy-discriminating the secondary electron obtained by scanning a primary charged particle beam emitted from a charged particle source on a sample;
generating, by a computer, a scan image for each frame of a plurality of frames obtained by the detector based on a detection signal amount of the detector that fluctuates according to scanning of the primary charged particle beam, wherein the scan image for each frame is acquired by continuously scanning a specific portion of the sample with the primary charged particle beam;
calculating, by the computer, a charging amount for each frame based on an output of the scan image for each frame; and
outputting information on the charging amount by the computer.

Assignees

• Hitachi High Tech Corp

Inventors

• Ishizaka Fumiya
• Bizen Daisuke
• Suzuki Makoto

Classifications

• H01J2237/2803

  characterised by the imaging method · CPC title

• H01J37/147

  Arrangements for directing or deflecting the discharge along a desired path ({H01J37/045 take precedence;} lenses H01J37/10) · CPC title

• H01J37/28 Primary

  with scanning beams {(H01J37/268, H01J37/292, H01J37/2955 take precedence)} · CPC title

• H01J37/244

  Detectors; Associated components or circuits therefor · CPC title

• H01J2237/2817

  Pattern inspection · CPC title