Multipole lens, aberration corrector, and electron microscope

Patent metadata

Field	Value
Publication number	US-9349565-B2
Application number	US-201514688045-A
Country	US
Kind code	B2
Filing date	Apr 16, 2015
Priority date	Apr 17, 2014
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

A multipole lens ( 100 ) which can produce static magnetic fields showing different strengths in the direction of travel of an electron beam has lens subasssemblies ( 10 a, 10 b, 10 c ) stacked on top of each other. The lens subassemblies ( 10 a, 10 b, 10 c ) have yokes ( 14 a, 14 b, 14 c ), respectively, and polar elements ( 12 a, 12 b, 12 c ), respectively. The polar elements ( 12 a, 12 b, 12 c ) have base portions ( 13 a, 13 b, 13 c ), respectively, magnetically coupled to the yokes ( 14 a, 14 b, 14 c ), respectively, and front end portions ( 11 a, 11 b, 11 c ), respectively, magnetically coupled to the base portions ( 13 a, 13 b, 13 c ), respectively. Magnetic field separators ( 20, 22 ) made of a nonmagnetic material are mounted between the front end portions ( 11 a, 11 b, 11 c ) which are successively adjacent to each other in the direction of stacking of the lens subassemblies ( 10 a, 10 b, 10 c ).

First claim

The invention claimed is:

1. A multipole lens comprising:
a plurality of lens subassemblies stacked on top of each other, each of the lens subassemblies having a yoke and polar elements, each of the polar elements having a base portion magnetically coupled to the yoke and a front end portion magnetically coupled to said base portion; and
magnetic field separators made of a nonmagnetic material and mounted between said front end portions which are successively adjacent to each other in the direction of stacking of said lens subassemblies.

2. The multipole lens as set forth in claim 1 , wherein said magnetic field separators have electrical conductivity.

3. The multipole lens as set forth in claim 1 , further comprising terminals for applying voltages to said front end portions.

4. The multipole lens as set forth in claim 1 , wherein said base portions are spaced from said front end portions.

5. The multipole lens as set forth in claim 1 , wherein said polar elements which are successively adjacent to each other in the direction of stacking produce electric fields of equal strength, and wherein said polar elements which are successively adjacent to each other in the direction of stacking produce magnetic fields of different strengths.

6. The multipole lens as set forth in claim 1 , wherein said magnetic field separators are in contact with respective ones of said front end portions which are adjacent to their respective magnetic field separators in the direction of stacking.

7. The multipole lens as set forth in claim 1 , wherein first support portions made of a nonmagnetic material are mounted between said base portions which are successively adjacent to each other in the direction of stacking.

8. The multipole lens as set forth in claim 1 , wherein second support portions made of a nonmagnetic material are mounted between said yokes which are successively adjacent to each other in the direction of stacking.

9. The multipole lens as set forth in claim 1 , further comprising:
first coils mounted on said base portions, respectively; and
second coils mounted on said base portions, respectively, each of the second coils having a fewer number of turns than each of said first coils.

10. An aberration corrector including a multipole lens as set forth in claim 1 .

11. The aberration corrector as set forth in claim 10 , wherein said multipole lens produces an electromagnetic field for canceling out chromatic aberration.

12. An electron microscope including an aberration corrector as set forth in claim 10 .

13. The electron microscope as set forth in claim 12 , wherein vacuum partitions are disposed between said base portions and said front end portions.

Assignees

• Jeol Ltd

Inventors

• Sawada Hidetaka

Classifications

• H01J2237/063

  Electron sources · CPC title

• H01J2237/1415

  Bores or yokes, i.e. magnetic circuit in general · CPC title

• H01J37/141 Primary

  Electromagnetic lenses · CPC title

• H01J37/153

  Electron-optical or ion-optical arrangements for the correction of image defects, e.g. stigmators · CPC title

• H01J37/06

  Electron sources; Electron guns · CPC title