Charged particle beam apparatus and method of correcting landing angle of charged particle beam

• US 9,679,744 B2
• Filed: 11/06/2012
• Issued: 06/13/2017
• Est. Priority Date: 11/08/2011
• Status: Active Grant

• Current Assignee: Hitachi High-Tech Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: Shirai, Masumi
• Primary Examiner(s): Johnston, Phillip A
• Assistant Examiner(s): TSAI, HSIEN C
• Application Number:
  US14/356,166
• Publication Number:
  US 20150053855A1
• Time in Patent Office: 1,680 Days
• Field of Search: 250307, 250311, 250306, 250309, 250310, 2504911, 25049222
• CPC Class Codes: G01B 15/00 Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons characterised by the use of optical techniques G01B9/00, G01B11/00
• CPC Class Codes: H01J 2237/2806 Secondary charged particle
• CPC Class Codes: H01J 2237/2809 characterised by the imaging problems involved
• CPC Class Codes: H01J 2237/2817 Pattern inspection
• CPC Class Codes: H01J 37/147 Arrangements for directing or deflecting the discharge along a desired path H01J37/045 take precedence; lenses H01J37/10
• CPC Class Codes: H01J 37/20 Means for supporting or positioning the object or the material; Means for adjusting diaphragms or lenses associated with the support
• CPC Class Codes: H01J 37/22 Optical , image processing or photographic arrangements associated with the tube
• CPC Class Codes: H01J 37/222 Image processing arrangements associated with the tube
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence

Abstract

A scanning electron microscope (SEM) is configured so that SEM images are acquired while scanning a pyramid pattern on a sample plane from four directions. Landing angle of the electron beam is calculated from these SEM images, which are then averaged, whereby inclination angle of the electron beam that is less influenced from scan distortion can be found.

Claims

1. A charged particle beam apparatus, comprising:

an image acquisition unit configured to;

acquire at least a first charged particle beam image by scanning a polyhedral structure having a known shape, which is formed on a sample plane, in a first scanning direction using a charged particle beam,

change a scanning direction of the charged particle beam or a loading direction of a sample in which the polyhedral structure is disposed so that a scan line direction of the charged particle beam with respect to the polyhedral structure changes, and

acquire at least a second charged particle beam image by scanning the polyhedral structure in a second scanning direction, oriented 180°

with respect to the first scanning direction, using the charged particle beam; and

a landing angle measurement unit configured to;

measure a landing angle of the charged particle beam for each of the acquired charged particle beam images based on a geometric deformation of the polyhedral structure in the respective image, and

average the landing angles of the charged particle beam for the first and second scanning directions.

2. The charged particle beam apparatus according to claim 1, wherein the image acquisition unit changes a rotation angle between 0°

, 180°

, 90° and

270°

by raster rotation to provide opposite scanning directions, and acquires a charged particle beam image of the polyhedral structure corresponding to each rotation angle in an image shift manner.

3. The charged particle beam apparatus according to claim 1, wherein the image acquisition unit changes a wafer loading angle of the sample between 0°

and 180°

to provide opposite loading directions, and acquires a charged particle beam image of the polyhedral structure corresponding to each wafer loading angle in an image shift manner.

4. The charged particle beam apparatus according to claim 2, wherein a measurement error suppression unit is configured to average the landing angles of the charged particle beam for the first and second scanning directions for the landing angle measurement unit.

6. The charged particle beam apparatus according to claim 1, wherein each scanning direction is in a plane parallel to the sample plane.

5. A method of correcting landing angle, comprising the steps of:

acquiring at least a first charged particle beam image by scanning a polyhedral structure having a known shape, which is formed on a sample plane, in a first scanning direction using a charged particle beam;

changing a scanning direction of the charged particle beam or a loading direction of a sample in which the polyhedral structure is disposed so that a scan line direction of the charged particle beam with respect to the polyhedral structure changes;

acquiring at least a second charged particle beam image by scanning the polyhedral structure in a second scanning direction, oriented 180°

with respect to the first scanning direction, using the charged particle beam;

measuring a landing angle of the charged particle beam for each of the acquired charged particle beam images based on a geometric deformation of the polyhedral structure in the respective image; and

averaging the landing angles of the charged particle beam for the first and second scanning directions.

7. The method according to claim 5, wherein each scanning direction is in a plane parallel to the sample plane.

8. A charged particle beam apparatus, comprising:

an image acquisition unit configured to, in order to acquire a first image by two-dimensionally scanning a polyhedral structure having a known shape, which is formed on a sample plane, by sequentially moving a position of a scanning line, which is formed by moving a charged particle beam irradiation position in at least a first direction, in a third direction that is orthogonal to the first direction, and in order to acquire a second image by two-dimensionally scanning the polyhedral structure by sequentially moving a position of a scanning line, which is formed by moving a charged particle beam irradiation position in a second direction that is opposite to the first direction, in a fourth direction that is opposite to the third direction, change a scanning direction of the charged particle beam or a loading direction of a sample in which the polyhedral structure is disposed so that a scan line direction of the charged particle beam with respect to the polyhedral structure changes, thereby acquiring the images; and

a landing angle measurement unit configured to, for the plurality of images of different scanning directions acquired by the image acquisition unit, measure landing angles of a plurality of charged particle beams for the respective scanning directions from the plurality of images of different scanning directions based on a geometric deformation of the polyhedral structure in the respective images, and average the landing angles of the charged particle beams for the respective scanning directions.

9. The charged particle beam apparatus according to claim 8, wherein the image acquisition unit changes a rotation angle between 0°

, 180°

, 90° and

270°

by raster rotation to provide opposite scanning directions, and acquires a charged particle beam image of the polyhedral structure corresponding to each rotation angle in an image shift manner.

10. The charged particle beam apparatus according to claim 8, wherein the image acquisition unit changes a wafer loading angle of the sample between 0°

and 180°

to provide opposite loading directions, and acquires a charged particle beam image of the polyhedral structure corresponding to each wafer loading angle in an image shift manner.

11. The charged particle beam apparatus according to claim 9, wherein a measurement error suppression unit is configured to average the landing angles of the charged particle beam for the first and second scanning directions for the landing angle measurement unit.

12. The charged particle beam apparatus according to claim 8, wherein each scanning direction is in a plane parallel to the sample plane.