Scanning transmission electron microscope and axial adjustment method thereof

• US 8,710,438 B2
• Filed: 07/11/2011
• Issued: 04/29/2014
• Est. Priority Date: 07/27/2010
• Status: Expired due to Fees

• Current Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: Nakamura, Kuniyasu, Inada, Hiromi
• Primary Examiner(s): Berman, Jack
• Assistant Examiner(s): CHUNG, KEVIN T
• Application Number:
  US13/808,134
• Publication Number:
  US 20130112875A1
• Time in Patent Office: 1,023 Days
• Field of Search: 250/311, 250/307
• US Class Current: 250/311
• CPC Class Codes: H01J 2237/0451 with fixed aperture
• CPC Class Codes: H01J 2237/1501 Beam alignment means or procedures
• CPC Class Codes: H01J 2237/2802 Transmission microscopes
• CPC Class Codes: H01J 37/263 Contrast, resolution or power of penetration
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence

Abstract

A scanning transmission electron microscope equipped with an aberration corrector is capable of automatically aligning the position of a convergence aperture with the center of an optical axis irrespective of skill and experience of an operator. The scanning transmission electron microscope system includes an electron source; a condenser lens configured to converge an electron beam emitted from the electron source; a deflector configured to cause the electron beam to perform scanning on a sample; an aberration correction device configured to correct an aberration of the electron beam; a convergence aperture configured to determine a convergent angle of the electron beam; and a detector configured to detect electrons passing through or diffracted by the sample. The system acquires information on contrast of a Ronchigram formed by the electron beam passing through the sample, and determines a position of the convergence aperture on the basis of the information.

Claims

1. A scanning transmission electron microscope system, comprising:

an electron source;

a condenser lens configured to converge an electron beam emitted from the electron source;

a deflector configured to cause the electron beam to perform scanning on a sample;

an aberration correction device configured to correct an aberration of the electron beam;

a convergence aperture configured to determine a convergent angle of the electron beam; and

a detector configured to detect electrons passing through or diffracted by the sample, wherein

the system acquires information on contrast of a Ronchigram formed by the electron beam passing through the sample, and determines a position of the convergence aperture on the basis of the information.

2. The scanning transmission electron microscope system according to claim 1, the system further comprising

an operating unit configured to create a histogram of the Ronchigram, wherein

the position of the convergence aperture is determined on the basis of the histogram.

3. The scanning transmission electron microscope system according to claim 1, the system further comprising

an operating unit configured to create a histogram of an image obtained by differentiating the Ronchigram, wherein

the position of the convergence aperture is determined on the basis of the histogram.

4. The scanning transmission electron microscope system according to claim 1, the system further comprising

a driving mechanism configured to two-dimensionally drive the convergence aperture, wherein

the information on the contrast of the Ronchigram is acquired by obtaining the Ronchigram synchronously with drive of the convergence aperture, and

the position of the convergence aperture is determined on the basis of the information.

5. The scanning transmission electron microscope system according to claim 1, wherein

the Ronchigram is obtained synchronously with tilt of the electron beam, and

an optical axis is determined by using a histogram of the obtained Ronchigram.

6. The scanning transmission electron microscope system according to claim 5, wherein

the tilt of the electron beam is set automatically in such a manner that a position of the optical axis coincides with the position of the convergence aperture upon determination of the optical axis.