Scanning microscope having an adaptive scan

• US 9,041,793 B2
• Filed: 05/17/2012
• Issued: 05/26/2015
• Est. Priority Date: 05/17/2012
• Status: Active Grant

• Current Assignee: FEI Company (Thermo Fisher Scientific Incorporated)
• Original Assignee: FEI Company (Thermo Fisher Scientific Incorporated)
• Inventors: Bugge, Cliff, van Leer, Brandon
• Primary Examiner(s): ELAHI, SHAN E
• Application Number:
  US13/474,176
• Publication Number:
  US 20130307957A1
• Time in Patent Office: 1,104 Days
• Field of Search: 348/79
• US Class Current: 348/79
• CPC Class Codes: C07K 14/415 from plants
• CPC Class Codes: C12N 15/8247 involving modified lipid metabolism, e.g. seed oil composition
• CPC Class Codes: G02B 21/002 Scanning microscopes scanning near field optical microscopes G01Q60/18
• CPC Class Codes: H01J 2237/2813 characterised by the application
• CPC Class Codes: H01J 37/222 Image processing arrangements associated with the tube image data processing or generation, in general G06T
• 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
• CPC Class Codes: H04N 7/18 Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast

Abstract

A method of using a scanning microscope to rapidly form a digital image of an area. The method includes performing an initial set of scans to form a guide pixel set for the area and using the guide pixel set to identify regions representing structures of interest in the area. Then, performing additional scans of the regions representing structures of interest, to gather further data to further evaluate pixels in the regions, and not scanning elsewhere in the area.

Claims

1. A method of using a scanning microscope to rapidly form an image of a specimen, comprising:

performing an initial scan or set of scans of a first area of the specimen composed of a first set of pixels to determine a first gray level for each of the pixels in the first set of pixels;

analyzing the first gray levels of the pixels in the first set of pixels to identify first regions representing structures of interest in said first area, said first regions including fewer pixels than the number of pixels in the first set of pixels, wherein analyzing the first gray levels of the pixels includes comparing the first gray level of the pixels to thresholds, the thresholds depending on the gray level of adjacent pixels;

performing additional scans of said first regions using the scanning microscope to determine second gray level values of only pixels of said first regions, the second gray level values being determined by integrating more scans than the number of scans used to determine the first gray levels, thereby improving an accuracy of the measured gray level value of pixels in the first regions while including fewer pixels in the additional scans; and

progressively removing material from the specimen to reveal a new surface and each time a new surface is revealed, scanning a limited region of each new surface, the limited region being determined by the gray level of pixels in a previous scan.

2. A scanning charged particle beam system, comprising:

a source of charged particles;

deflectors for scanning the specimen with a charged particle beam;

a lens for focusing the charged particle beam onto the specimen;

a detector for detecting emissions from the specimen in response to impacts of the charged particles with the specimen;

a computer for controlling an operation of the scanning charged particle beam system; and

computer readable memory device that stores instructions to perform the method of claim 1.

3. The method of claim 1 in which the thresholds depend on the gray level of adjacent pixels and on number of integrated scans used to determine the first gray levels of the pixels.

4. The method of claim 1, further comprising:

exposing a second area by removing from the specimen a layer of material that includes the first area; and

scanning a second region of the second area, the second region comprising a subset of pixels in the second area and determined by the first regions.

5. The method of claim 1 in which the thresholds are determined by the gray level of neighboring pixels and the gray level of pixels at the same location in a previous surface.

6. A method of forming an image using a scanning beam, comprising:

scanning a surface of a specimen in a field of view to determine pixel values in the field of view;

analyzing the pixel values to determine a subset of pixels that represent a feature of interest; and

performing additional scans using the scanning beam over only the subset of pixels to produce an image of the feature of interest, wherein performing the additional scans includes;

removing a layer of material from the specimen to expose a subsequent surface of the specimen, and

scanning the subsequent surface using the scanning beam, the pixels of the subsequent surface that are scanned being determined by the gray level of the corresponding pixels in a previously scanned surf.

7. The method of claim 6 in which analyzing the pixels includes comparing the gray level of the pixels to threshold values.

8. The method of claim 7 in which the threshold values depend on the number of scans used to determine the pixel values.

9. The method of claim 7 in which the threshold values depend on the gray level of adjacent pixels.

10. The method of claim 6 in which removing a layer of material from the specimen to expose a subsequent surface and scanning the subsequent surface using the scanning beam, the pixels of the subsequent surface that are scanned being determined by the gray level of the corresponding pixels in the previously scanned surface, is repeated to form a three dimensional image.

11. A method of using a scanning microscope to rapidly form an image of a specimen, comprising:

performing an initial scan or set of scans of a first area of the specimen composed of a first set of pixels to determine a first gray level for each of the pixels in the first set of pixels;

analyzing the first gray levels of the pixels in the first set of pixels to identify first regions representing structures of interest in said first area, said first regions including fewer pixels than the number of pixels in the first set of pixels;

performing additional scans of said first regions using the scanning microscope to determine second gray level values of only pixels of said first regions, the second gray level values being determined by integrating more scans than the number of scans used to determine the first gray levels, thereby improving an accuracy of the measured gray level value of pixels in the first regions while including fewer pixels in the additional scans;

analyzing the second gray level values to identify second regions representing the structures of interest in said first area, said second regions being a subset of and including fewer pixels than the first set of pixels; and

performing additional scans using the scanning microscope of said second regions to determine third gray level values of only pixels of said second regions, the third gray level values being determined by integrating more scans than the number of scans used to determine the second gray levels.