Method of adjusting a stigmator in a particle beam apparatus and a Particle beam system

Patent metadata

Field	Value
Publication number	US-9455115-B2
Application number	US-201414574190-A
Country	US
Kind code	B2
Filing date	Dec 17, 2014
Priority date	Dec 17, 2014
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

A method of adjusting a stigmator in a particle beam apparatus comprises directing a particle beam onto a sample wherein the particle beam traverses a quadrupole field 37 generated by energizing at least four field generators of the stigmator; acquiring first and second images of the sample at different field strengths of the quadrupole field while energizing the at least four field generators according to a first setting of a plurality of settings; acquiring third and fourth images of the sample at different field strengths of the quadrupole field 37 while energizing the at least four field generators according to a second setting of the plurality of settings; determining a plurality of image displacements based on the first, second, third and fourth images; determining an optimum setting of the at least four field generators based on the plurality of image displacements and the plurality of settings.

First claim

The invention claimed is:

1. A method of adjusting a stigmator in a charged particle beam apparatus, wherein the method comprises:
directing a charged particle beam onto a sample wherein the charged particle beam traverses a quadrupole field generated by energizing at least four field generators of the stigmator,
acquiring first and second images of the sample at different field strengths of the quadrupole field while energizing the at least four field generators according to a first setting of a plurality of settings of the at least four field generators,
acquiring third and fourth images of the sample at different field strengths of the quadrupole field while energizing the at least four field generators according to a second setting of a plurality of settings of the at least four field generators,
determining a plurality of image displacements, wherein a first image displacement of the plurality of image displacements is determined based on the first and second images and wherein a second image displacement of the plurality of image displacements is determined based on the third and fourth images,
determining an optimum setting of the at least four field generators based on the plurality of image displacements and the plurality of settings of the at least four field generators so that an image displacement between two images acquired while energizing the at least four field generators according to the optimum setting at field strengths differing from each other by 1% of a maximum excitation of the at least four field generators is less than a predetermined limit,
wherein the maximum excitation of the at least four field generators is a largest value of maximum excitations of each of the at least four field generators,
wherein the optimum setting of the at least four field generators is determined by evaluating a mathematical formula, the only constituents of which are two image displacements of the plurality of image displacements, the plurality of settings used for acquiring images based on which the two image displacements were determined and at least one of at least one constant and at least one parameter, wherein the at least one parameter is independent of the plurality of image displacements and independent of the plurality of settings.

2. The method according to claim 1 , wherein the determining of the optimum setting of the at least four field generators is free of determining at least one parameter depending on at least one of the properties of the charged particle beam, an axis deviation of the charged particle beam from an optical axis of an objective lens, and a particle optical system of the charged particle beam apparatus.

3. The method according to claim 1 , wherein the mathematical formula is given by or representable as:

s
→

0

=

H
⁡

[

F
⁢

d
→

1

·
G

⁢

s
→

2

-

F
⁢

d
→

2

·
G

⁢

s
→

1

F
(

d
→

1

-

d
→

2

)

]

wherein
{right arrow over (s)} 0 denotes a two-dimensional representation of the optimum setting,
{right arrow over (d)} 1 and {right arrow over (d)} 2 denote a two-dimensional representation of the first and second image displacements, respectively,
{right arrow over (s)} 1 and {right arrow over (s)} 2 denote a two-dimensional representation of the first and second settings, respectively,
F denotes an operator acting on {right arrow over (d)} 1 and {right arrow over (d)} 2 ,
G denotes an operator acting on {right arrow over (s)} 1 and {right arrow over (s)} 2 , and
H denotes an operator acting on

F
⁢

d
→

1

·
G

⁢

s
→

2

-

F
⁢

d
→

2

·
G

⁢

s
→

1

F
(

d
→

1

-

d
→

2

)

.

4. The method according to claim 3 , wherein the operators F, G and H comprise at least one of an operation of scaling, an operation of rotation, an operation

Assignees

• Zeiss Carl Microscopy Gmbh

Inventors

• Diemer Simon

Classifications

• H01J37/153 Primary

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

• H01J37/285

  Emission microscopes, e.g. field-emission microscopes · CPC title

• H01J2237/12

  electrostatic · CPC title

• H01J2237/1534

  Aberrations · CPC title

• H01J37/147 Primary

  Arrangements for directing or deflecting the discharge along a desired path ({H01J37/045 take precedence;} lenses H01J37/10) · CPC title