Electron microscope device and imaging method using same

• US 9,824,853 B2
• Filed: 05/27/2015
• Issued: 11/21/2017
• Est. Priority Date: 07/02/2014
• Status: Active Grant

• Current Assignee: Hitachi High-Tech Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: Kobayashi, Mitsutoshi, Nakahira, Kenji, Tanaka, Maki
• Primary Examiner(s): Vanore, David A
• Application Number:
  US15/312,866
• Publication Number:
  US 20170169992A1
• Time in Patent Office: 909 Days
• Field of Search: 250307, 250310
• CPC Class Codes: H01J 2237/221 Image processing
• CPC Class Codes: H01J 2237/24592 Inspection and quality control of devices
• CPC Class Codes: H01J 2237/2809 characterised by the imaging problems involved
• CPC Class Codes: H01J 2237/2817 Pattern inspection
• CPC Class Codes: H01J 37/244 Detectors; Associated components or circuits therefor
• CPC Class Codes: H01J 37/263 Contrast, resolution or power of penetration
• CPC Class Codes: H01J 37/265 Controlling the tube; circuit arrangements adapted to a particular application not otherwise provided, e.g. bright-field-dark-field illumination
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence

Abstract

In order to enable high-speed imaging of a wide-field image, the imaging method using the electron microscope comprises: irradiating and scanning a wide-field region of the sample with a low-dose amount of electron beam, and acquiring a wide-field image of the sample; setting, from this wide-field image, a narrow-field region; irradiating and scanning this narrow-field region with a high-dose amount of the electron beam, and acquiring a narrow-field image of the sample; determining the noise-removal parameters for the acquired wide-field image and narrow-field image; performing image quality improvement processing on the wide-field image and the narrow-field image; performing drift correction on the narrow-field image undergone the image quality improvement processing; and combining the narrow-field image undergone this drift correction and the wide-field image in such a manner that the visibility of each is at the same level throughout the entirety of the combined image.

Claims

1. An electron microscope that irradiates a focused electron beam on a sample and acquires an image of the sample, comprising:

a processing unit which sets processing conditions for acquiring the image of the sample;

an image processing unit which processes the image of the sample being acquired;

an input/output unit which inputs the conditions for acquiring the image of the sample and outputs a result that was processed in the image processing unit; and

a control unit which controls the image processing unit and the input/output unit,

wherein the image processing unit comprises

an image region setting unit that sets a wide field region of a relatively wide visual field for acquiring the image of the sample and one or more narrow field regions of a relatively narrow visual field included in the inside of the wide field region, and sets so that dose amounts per pixel of a wide field image and a narrow field image acquired by imaging the wide field image and the narrow field image may become larger in the narrow field image than in the wide field image;

a parameter determining unit that determines a parameter of image quality improvement processing of the wide field region and the narrow field region according to a dose amount per pixel of each region;

an image quality improvement processing unit that performs the image quality improvement processing of the wide field image and the narrow field image based on the parameter determined in the parameter determining unit; and

an image combining unit that combines an image by performing the image quality improvement processing in the image quality improvement processing unit.

2. The electron microscope device according to claim 1,

wherein the image region setting unit sets the wide field region or the narrow field region based on one or more pieces of information among a user'"'"'s input and structure information judged from a change of a brightness value in the narrow field image or the wide field image acquired with the electron microscope.

3. The electron microscope device according to claim 1,

wherein the processing unit sets imaging conditions related to the dose amount, a magnification, and a scanning method in the wide field region and the narrow field region that were set by the image region setting unit based on one or more pieces of information among a user'"'"'s input and structure information as processing conditions for acquiring the image of the sample.

4. The electron microscope device according to claim 2,

wherein the image region setting unit judges the structure information in the image from a brightness change in the narrow field image or the wide field image whose image quality was improved by the image quality improvement processing unit.

5. The electron microscope device according to claim 1,

wherein the parameter determining unit sets a parameter of the image quality improvement processing in each region of the combined image based on intensity of noise removal.

6. The electron microscope device according to claim 1,

wherein the image combining unit corrects drift of one or more of the narrow field images using one or more pieces of information among the wide field image, structure information, and an image in process of combination of the narrow field image and the wide field image.

7. The electron microscope device according to claim 1,

wherein the parameter determining unit determines the parameter so that degrees of intensity in all the regions of the combined image of the wide field image and one or more of the narrow field images may be equalized.

8. An imaging method using an electron microscope device that irradiates a focused electron beam on a sample and acquires an image of the sample, comprising the steps of:

setting initial conditions for acquiring the image of the sample by an input/output unit;

setting by a processing unit a wide field region of the sample and one or more narrow field regions that are relatively narrow included in the inside of the wide field region based on the initial conditions set by the input/output unit;

setting an image processing unit so that a dose amount per pixel of the wide field image and the narrow field image obtained by imaging, with the electron microscope device, the wide field region and the narrow field region may become larger in the narrow field image than in the wide field region;

determining, in the image processing unit, image quality improvement parameters of the images of the wide field region and the narrow field region acquired by the imaging according to the dose amount per pixel of each region;

performing image quality improvement processing on the images of the wide field region and the narrow field region using the determined image quality improvement parameters by the image processing unit; and

combining, in the image processing unit, the images of the wide field region and the narrow field region on which the image quality improvement processing was performed by the image processing unit.

9. The imaging method using an electron microscope device according to claim 8,

wherein the wide field region or the narrow field region is set by the processing unit based on one or more pieces of information among a user'"'"'s input and structure information judged from a change of a brightness value in the narrow field image or the wide field image acquired with an electron microscope.

10. The imaging method using an electron microscope device according to claim 8,

wherein imaging conditions related to the dose amount, a magnification, and a scanning method in the wide field region and the narrow field region being set are set by the image processing unit based on one or more pieces of information among a user'"'"'s input and structure information as processing conditions for acquiring the image of the sample.

11. The imaging method using an electron microscope device according to claim 9,

wherein the structure information in the image is judged from a brightness change in the narrow field image or the wide field image whose image quality was improved by the image processing unit.

12. The imaging method using an electron microscope device according to claim 8,

wherein the parameter of the image quality improvement processing in each region of the combined image is set by the image processing unit based on intensity of noise removal.

13. The imaging method using an electron microscope device according to claim 8,

wherein in a process of combining the wide field image and the narrow field image by the image processing unit, one or more of the narrow field images are drift corrected using one or more pieces of information among the wide field image, structure information, and an image in process of combination of the wide field image and the narrow field image.

14. The imaging method using an electron microscope device according to claim 8,

wherein the image quality improvement parameter is determined by the mage processing unit so that degrees of noise in all the regions of the combined image of the wide field image and one or more narrow field images may become comparable.

15. The imaging method using an electron microscope device according to claim 8, comprising the steps of:

acquiring, by an electron microscope a frame image comprising the wide field image and the narrow field image included in the wide field image of the sample by irradiating a focused electron beam onto the wide field region and narrow field regions included in the wide field region with a relatively high dose amount in the narrow field region and with a relatively low dose amount in the wide field region other than the narrow field regions;

performing the image quality improvement processing on the acquired frame image by the image processing unit; and

performing frame addition of a plurality of frame images on which the image quality improvement processing was performed by the image processing unit after drift correcting the images.

16. The imaging method using an electron microscope device according to claim 15,

wherein in acquiring a plurality of frame images, setting of the narrow field region is changed by the processing unit according to structure information.