# US 2020/0286705 A1 · Apparatus of plural charged-particle beams

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- Number: US 2020/0286705 A1
- Document ID: US20200286705A1
- Status: Published application
- Kind: A1
- Application number: 16/799,773
- Filed: 2020-02-24
- Published: 2020-09-10
- Earliest claimed: 2015-05-12
- Assignees: ASML Netherlands B.V.
- Applicants: ASML Netherlands B.V.
- Inventors: Xuedong LIU; Weiming REN; Shuai LI; Zhongwei CHEN
- Web page: https://patentgrep.com/patent/US20200286705A1

## CPC

- H01J 37/147: Arrangements for directing or deflecting the discharge along a desired path ({H01J37/045 take precedence;} lenses H01J37/10)
- H01J 37/04: Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement {(H01J37/32009, H01J37/32623, H01J37/3266, H01J37/32697 take precedence; electron or ion-optical systems for localised treatment of objects H01J37/3007)}
- H01J 37/153: Electron-optical or ion-optical arrangements for the correction of image defects, e.g. stigmators
- H01J 37/28: with scanning beams {(H01J37/268, H01J37/292, H01J37/2955 take precedence)}
- H01J 2237/061: Construction
- H01J 2237/083: Beam forming
- H01J 2237/1532: Astigmatism
- H01J 2237/1534: Aberrations
- H01J 2237/2817: Pattern inspection
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

One modified source-conversion unit and one method to reduce the Coulomb Effect in a multi-beam apparatus are proposed. In the modified source-conversion unit, the aberration-compensation function is carried out after the image-forming function has changed each beamlet to be on-axis locally, and therefore avoids undesired aberrations due to the beamlet tilting/shifting. A Coulomb-effect-reduction means with plural Coulomb-effect-reduction openings is placed close to the single electron source of the apparatus and therefore the electrons not in use can be cut off as early as possible.

## Claims

### Claim 1

(canceled)

### Claim 2

A source-conversion unit to convert an electron source to multiple images of the electron source, the source-conversion unit comprising:
a micro-deflector array configured to convert an electron beam from the electron source into a plurality of electron beamlets, and
a micro-compensator array configured to compensate aberrations of a first beamlet and a second beamlet of the plurality of electron beamlets, the micro-compensator array comprising:
a first micro-compensator layer comprising a first lens and a second lens, each of the first and second lenses comprising an electrode; and
a second micro-compensator layer comprising a third lens and a fourth lens, each of the third and fourth lenses comprising an electrode,
wherein the first and the third lenses are aligned each other with respect to a first local optical axis and configured to compensate the aberration of the first beamlet, and
the second and the fourth lenses are aligned each other with respect to a second local optical axis and configured to compensate the aberration of the second beamlet.

### Claim 3 (depends on 2)

The source-conversion unit of claim 2, wherein each of the multiple images is associated with a corresponding beamlet of the plurality of electron beamlets.

### Claim 4 (depends on 2)

The source-conversion unit of claim 2, wherein the multiple images of the electron source comprise a virtual image of the electron source.

### Claim 5 (depends on 4)

The source-conversion unit of claim 4, wherein the multiple images of the electron source further comprise a real image of the electron source.

### Claim 6 (depends on 2)

The source-conversion unit of claim 2, wherein the first beamlet of the plurality of electron beamlets travels along with the first local optical axis.

### Claim 7 (depends on 2)

The source-conversion unit of claim 2, wherein the second beamlet of the plurality of electron beamlets travels along with the second local optical axis.

### Claim 8 (depends on 2)

The source-conversion unit of claim 2, wherein the micro-compensator array is configured to add a first compensating-aberration to reduce the aberration of the first beamlet and add a second compensating-aberration to reduce the aberration of the second beamlet.

### Claim 9 (depends on 8)

The source-conversion unit of claim 8, wherein each of the first compensating-aberration and the second compensating-aberration comprises a quadrupole field for compensating an astigmatism aberration and a round-lens field for compensating a field curvature aberration.

### Claim 10 (depends on 9)

The source-conversion unit of claim 9, wherein:
the first and the third lenses are 4-pole lenses and have a 45-degree difference in orientation, and
the second and the fourth lenses are 4-pole lenses and have a 45-degree difference in orientation.

### Claim 11 (depends on 10)

The source-conversion unit of claim 10, wherein:
the first and the second lenses each have a same orientation angle, and
the third and the fourth lenses each have a same orientation angle.

### Claim 12 (depends on 11)

The source-conversion unit of claim 11, wherein:
the first and the third lenses are configured to generate in combination the quadrupole field of the first compensating-aberration, and
the second and the fourth lenses are configured to generate in combination the quadrupole field of the second compensating-aberration.

### Claim 13 (depends on 12)

The source-conversion unit of claim 12, wherein:
the first lens is configured to generate the round-lens field of the first compensating-aberration, and
the second lens is configured to generate the round-lens field of the second compensating-aberration.

### Claim 14 (depends on 9)

The source-conversion unit of claim 9, wherein the first and second lenses are round lenses, each of the first and second lenses comprising a single electrode.

### Claim 15 (depends on 14)

The source-conversion unit of claim 14, wherein the third and the fourth lenses are 4-pole lenses and have a 45-degree difference in orientation.

### Claim 16 (depends on 14)

The source-conversion unit of claim 14, wherein the third and the fourth lenses are 8-pole lenses.

### Claim 17 (depends on 16)

The source-conversion unit of claim 16, wherein:
the first lens is configured to generate the round-lens field of the first compensating-aberration, and
the second lens is configured to generate the round-lens field of the second compensating-aberration.

### Claim 18 (depends on 17)

The source-conversion unit of claim 17, wherein:
the third lens is configured to generate the quadrupole field of the first compensating-aberration, and
the fourth lens is configured to generate the quadrupole field of the second compensating-aberration.