Apparatus of plural charged-particle beams

Patent metadata

Field	Value
Publication number	US-10109456-B2
Application number	US-201715633639-A
Country	US
Kind code	B2
Filing date	Jun 26, 2017
Priority date	Mar 10, 2015
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

A multi-beam apparatus for observing a sample with high resolution and high throughput is proposed. In the apparatus, a source-conversion unit changes a single electron source into a virtual multi-source array, a primary projection imaging system projects the array to form plural probe spots on the sample, and a condenser lens adjusts the currents of the plural probe spots. In the source-conversion unit, the image-forming means is on the upstream of the beamlet-limit means, and thereby generating less scattered electrons. The image-forming means not only forms the virtual multi-source array, but also compensates the off-axis aberrations of the plurality of probe spots.

First claim

What is claimed is:

1. A source-conversion unit, comprising:
an image-forming element including:
a first layer with a first set of multi-pole structures, and
a second layer with a second set of multi-pole structures respectively corresponding to the first set of multi-pole structures,

wherein multi-pole structures of the first set of multi-pole structures are aligned with the respective multi-pole structures of the second set of multi-pole structures to form a plurality of pairs of multi-pole structures,
wherein a pair of multi-pole structures functions as at least a micro-deflector to deflect a beamlet of a charged particle beam generated by a charged particle source to form a virtual image of the charged particle source.

2. The source-conversion unit of claim 1 , wherein the pair of multi-pole structures functions as the micro-deflector, and at least one of a micro-lens to focus the beamlet to a desired degree and a micro-stigmator to add a desired amount of astigmatism aberration to the beamlet.

3. The source-conversion unit of claim 1 , further comprising:
a beamlet-limit element disposed below the image-forming element and including a plurality of beam-limit openings respectively corresponding to the plurality of pairs of multi-pole structures to limit a plurality of beamlets deflected by the plurality of pairs of multi-pole structures.

4. The source-conversion unit of claim 3 , wherein each one of the plurality of beam-limit openings is aligned with a corresponding pair of the plurality of pairs of multi-pole structures.

5. The source-conversion unit of claim 1 , wherein the first layer is an upper layer, and the second layer is a lower layer disposed below the first layer.

6. The source-conversion unit of claim 1 , wherein each multi-pole structure of the first set of multi-pole structures and the second set of multi-pole structures is a 4-pole structure.

7. The source-conversion unit of claim 6 , wherein in each pair of multi-pole structures, a multi-pole structure of the first layer and a multi-pole structure of the second layer have a 45° difference in azimuth.

8. The source-conversion unit of claim 1 , further comprising:
a first electric conduction plate with a plurality of through-holes, each through-hole is aligned with a corresponding pair of the plurality of pairs of multi-pole structures.

9. The source-conversion unit of claim 8 , wherein the first electric conduction plate is disposed below the plurality of pairs of multi-pole structures.

10. The source-conversion unit of claim 8 , wherein the first electric conduction plate is disposed above the plurality of pairs of multi-pole structures.

11. The source-conversion unit of claim 10 , further comprising:
a second electric conduction plate disposed below the plurality of pairs of multi-pole structures.

12. The source-conversion unit of claim 1 , wherein the charged particle source is an electron source, and the charged particle beam is an electron beam.

13. A multi-beam apparatus, comprising the source-conversion unit of claim 1 .

14. A method to configure a source-conversion unit, comprises:
providing an image-forming element including:
a first layer with a first set of multi-pole structures; and
a second layer with a second set of multi-pole structures respectively corresponding to the first set of multi-pole structures,

wherein multi-pole structures of the first set of multi-pole structures are aligned with the respective multiple-pole structures of the second set of multi-pole structures to form a plurality of pairs of multi-pole structures,
wherein a pair of multi-pole structures functions as a micro-deflector to deflect a beamlet of a charged particle beam generated by a charged particle source to form a virtual image of the charged particle source.

15. The method of claim 14 , wherein the pair of multi-pole structures functions as the micro-deflector, and at least one of a micro-lens to focus the beamlet to a desired degree and a micro-stigmator to add a desired amount of astigmatism aberration to the beamlet.

16. The method of claim 14 , further comprising:
providing a beamlet-limit element disposed below the image-forming element and including a plurality of beam-limit openings respectively corresponding to the plurality of pairs of multi-pole structures to limit a plurality of beamlets deflected by the plurality of pairs of multi-pole structures.

17. The method of claim 16 wherein each one of the plurality of beam-limit openings is aligned with a corresponding pair of the plurality of pairs of multi-pole structures.

18. The method of claim 14 , wherein the first layer is an upper layer, and the second layer is a lower layer disposed below the first layer.

19. The method of claim 14 , wherein each multi-pole structure of the first set of multi-pole structures and the second set of multi-pole structures is a 4-pole structure.

20. The method of claim 19 , wherein in each pair of multi-pole structures, a multi-pole structure of the first layer and a multi-pole structure of the second layer have a 45° difference in azimuth.

21. The method of claim 14 , further comprising:
providing a first electric conduction plate with a plurality of through-holes, each through-hole is aligned with a corresponding pair of the plurality of pairs of multi-pole structures.

22. The method of claim 21 , wherein the first electric conduction plate is disposed below the plurality of pairs of multi-pole structures.

23. The method of claim 21 , wherein the first electric conduction plate is disposed above the plurality of pairs of multi-pole structures.

24. The method of claim 23 , further comprising:
providing a second electric conduction plate disposed below the plurality of pairs of multi-pole structures.

25. The method of claim 24 , wherein the charged particle source is an electron source, and the charged particle beam is an electron beam.

26. A source-conversion unit, comprising:
an image-forming element including:
a first layer with a first set of multi-pole structures, and
a second layer with a second set of multi-pole structures,

wherein the first set of multi-pole structures are aligned with the second set of multi-pole structures to function as at least one of a micro-deflector to deflect a beamlet of charged particles, a micro-lens to focus the beamlet, and a micro-stigmator to add a desired amount of astigmatism aberration to the beamlet.

Assignees

• Hermes Microvision Inc
• Hermes Microvision Inc

Inventors

• Ren Weiming
• Li Shuai
• Liu Xuedong
• Chen Zhongwei

Classifications

• H01J2237/04924

  electrostatic · CPC title

• H01J37/28 Primary

  with scanning beams {(H01J37/268, H01J37/292, H01J37/2955 take precedence)} · CPC title

• H01J2237/2817

  Pattern inspection · CPC title

• H01J2237/083

  Beam forming · CPC title

• H01J2237/1205

  Microlenses · CPC title