Scanning electron microscope

• US 20010022346A1
• Filed: 11/30/2000
• Published: 09/20/2001
• Est. Priority Date: 11/30/1999
• Status: Active Grant

• Current Assignee: JEOL Engineering Company Limited, JEOL Limited
• Original Assignee: JEOL Limited
• Inventors: Katagami, Masumi, Kaneyama, Miyuki
• Granted Patent: US 6,528,787 B2
• Time in Patent Office: Days
• US Class Current: 250/310
• CPC Class Codes: H01J 2237/226 Image reconstruction
• CPC Class Codes: H01J 2237/2807 X-rays
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence

Abstract

A scanning electron microscope capable of imaging a specimen at a magnification lower than the minimum magnification of the microscope. The specimen surface is virtually partitioned into cells. The specimen is so moved that the cells can be individually scanned by the electron beam and hence image data can be taken from each cell. Image data derived from each cell by the scan is stored in locations of an image memory that are addressed corresponding to the positions of the cells.

Claims

1. A scanning electron microscope having a means for directing a sharply focused electron beam onto a specimen, a means for scanning said electron beam across the specimen in two dimensions, an image memory for storing image data obtained from the specimen by the scanning, a display means for displaying a specimen image based on the image data stored in said image memory, and a motor-driven specimen-moving device, said scanning electron microscope comprising:

a specimen motion control means for virtually partitioning an area on the specimen being scanned by the electron beam and from which an image may be taken into cells defined by grid lines and for moving said specimen to scan the cells individually by the electron beam;

an image-synthesizing means for storing image data obtained from these cells in locations of the image memory that are addressed corresponding to the cells, thus creating data defining a synthesized image;

a specifying means permitting an operator to specify an arbitrary area in the synthesized image displayed on the display means according to the data about the synthesized image; and

a partial image display means for reading image data about the area specified by the operator from said image memory and displaying the image data as a partial image.

2. The scanning electron microscope of

claim 1

, wherein said specimen motion control means moves said specimen such that adjacent ones of said cells are successively scanned by the electron beam.

3. The scanning electron microscope of

claim 1

or

2

, wherein said specimen motion control means moves said specimen according to a cell size found based on a magnification set by a microscope magnification-setting means.

4. The scanning electron microscope of

claim 1

or

2

, wherein said synthesized image and said partial image are simultaneously displayed on the viewing screen of a display device.

5. The scanning electron microscope of

claim 1

or

2

, wherein said specifying means permits an operator to specify an arbitrary region with a rectangular cursor of variable size.

6. The scanning electron microscope of

claim 1

or

2

, wherein said image-synthesizing means deletes data about image lying outside an image acceptance region from image data obtained from said area scanned by the electron beam and synthesizes an image.

7. The scanning electron microscope of

claim 6

, further comprising a means for specifying a ratio of said image acceptance region to the area scanned by said electron beam.

8. The scanning electron microscope of

claim 1

or

2

, wherein:

(A) there is further provided a cell-specifying means permitting an operator to specify a desired one of said cells;

(B) said specimen motion control means controls movement of the specimen such that the cell specified by said cell-specifying means is scanned by the electron beam; and

(C) said image-synthesizing means stores image data obtained from this cell in a location of the image memory that is addressed corresponding to the cell, thus creating data about a synthesized image.

9. The scanning electron microscope of

claim 8

, further comprising:

a comparison means for comparing image data obtained by scanning the cell specified by said cell-specifying means after the specimen is moved by the specimen motion control means to permit the cell to be scanned by the electron beam with image data already obtained from the same cell and finding misregistration between two images respectively formed by the two kinds of image data compared; and

a corrective means for correcting the position of the area on the specimen scanned with the electron beam by the scanning means according to information about the misregistration obtained from said comparison means.

10. The scanning electron microscope of

claim 9

, wherein said image data is obtained by detecting any one of secondary electrons, reflected electrons, and characteristic X-rays produced from the specimen.

11. A scanning electron microscope comprising:

a means for directing a sharply focused electron beam onto a specimen;

a means for scanning the electron beam across the specimen in two dimensions to produce charged particles and X-rays;

a charged-particle detector for detecting said produced charged particles;

an X-ray detector for detecting said produced characteristic X-rays;

a first image memory for storing image data derived from said charged-particle detector during the scanning of the electron beam;

a second image memory for storing data about an X-ray map of a certain element based on an output signal from the X-ray detector during the scanning of the electron beam;

a display means for displaying at least one of image data stored in the first image memory and X-ray map data stored in the second image memory as an observable still image;

a motor-driven specimen-moving device;

a specimen motion control means for virtually partitioning an area on the specimen being scanned by the electron beam and from which an image may be taken into cells defined by grid lines and for moving the specimen such that the cells can be individually scanned by the electron beam;

an image-synthesizing means for storing image data obtained from these cells by the charged-particle detector in locations of the first image memory that are addressed corresponding to the cells, thus creating data defining a synthesized image, said image-synthesizing means acting also to store map data about a certain element obtained from these cells by the X-ray detector in locations of the second image memory that are addressed corresponding to the cells, thus creating data about a synthesized map; and

a display means to which data about the synthesized image and the data about the synthesized map can be supplied.

12. The scanning electron microscope of

claim 11

, further comprising:

a specifying means permitting an operator to specify a desired region within the synthesized image displayed on said display means based on said synthesized image data or synthesized map data; and

a means for reading the synthesized image data or synthesized map data corresponding to the specified region within said synthesized image from said first image memory or said second image memory and displaying the data as a partial image.

13. The scanning electron microscope of

claim 11

, further comprising:

a specifying means permitting an operator to specify a desired region within the synthesized image displayed on said display means based on said synthesized image data; and

a means for reading the synthesized image data or synthesized map data corresponding to the specified region within said synthesized image from said first image memory or said second image memory and displaying the data as a partial image.

14. The scanning electron microscope of claims 11 or 12, wherein:

(A) there is further provided a specifying means permitting an operator to specify a desired one of said cells and to specify whether measurements of charged particles and characteristic X-rays from the specified cell are necessary;

(B) said specimen motion control means controls movement of the specimen such that the cell specified by said specifying means is scanned by the electron beam; and

(C) said image-synthesizing means stores at least one of image data and map data obtained from this cell by the measurements specified by the specifying means in locations of the image memory that are addressed corresponding to the cell, thus creating data about at least one of synthesized image and synthesized map.

15. The scanning electron microscope of

claim 14

, further comprising:

a comparison means for comparing image data obtained by scanning the cell specified by said specifying means after the specimen is moved by the specimen motion control means to permit the cell to be scanned by the electron beam with image data already obtained from the same cell and for finding misregistration between two images respectively formed by the two kinds of image data compared; and

a corrective means for correcting the position of the area on the specimen scanned with the electron beam by the scanning means according to information about the misregistration obtained from said comparison means.

16. The scanning electron microscope of

claim 15

, wherein said charged particles are secondary electrons or reflected electrons.