Charged particle optical apparatus for through-the-lens detection of particles

Patent metadata

Field	Value
Publication number	US-10861670-B2
Application number	US-201916725329-A
Country	US
Kind code	B2
Filing date	Dec 23, 2019
Priority date	Dec 1, 2015
Publication date	Dec 8, 2020
Grant date	Dec 8, 2020

Abstract

Disclosed is a charged particle optical apparatus. The charged particle optical apparatus has a liner electrode in a first vacuum zone. The liner electrode is used to generate an electrostatic objective lens field. The apparatus has a second electrode which surrounds at least a section of the primary particle beam path. The section extends in the first vacuum zone and downstream of the liner electrode. A third electrode is provided having a differential pressure aperture through which the particle beam path exits from the first vacuum zone. A particle detector is configured for detecting emitted particles, which are emitted from the object and which pass through the differential pressure aperture of the third electrode. The liner electrode, the second and third electrodes are operable at different potentials relative to each other.

First claim

The invention claimed is:

1. A charged particle optical apparatus, comprising:
a particle optical arrangement, configured to define a primary particle beam path for inspecting an object;
a specimen chamber configured to accommodate an object in a pressure-controlled interior of the specimen chamber during the inspection of the object;
a differential pressure module having a differential pressure aperture;
a first detector, wherein the first detector is a gaseous detector, wherein the first detector comprises plural collector electrodes distributed around the primary particle beam path; and
a second detector, wherein the second detector is a semiconductor detector having plural particle receiving surfaces distributed around the primary particle beam path,
wherein the first detector and the second detector are mounted on a common mounting structure.

2. The charged particle optical apparatus of claim 1 , wherein the first detector and the second detector are mounted on the differential pressure module.

3. The charged particle optical apparatus of claim 1 , wherein each collector electrode of the plural collector electrodes has a distal end portion pointing towards an interaction region where a primary particle beam generated by the particle optical apparatus interacts with the object during the inspection of the object.

4. The charged particle optical apparatus of claim 1 , wherein each collector electrode of the plural collector electrodes has a form of a wire.

5. The charged particle optical apparatus of claim 1 , wherein a number of the collector electrodes is four.

6. The charged particle optical apparatus of claim 1 , wherein a number of the particle receiving surfaces of the second detector is equal to a number of the collector electrodes of the first detector.

7. The charged particle optical apparatus of claim 1 , wherein circumferential positions of the collector electrodes correspond to circumferential positions of centers of gravity of the particle receiving surfaces.

8. The charged particle optical apparatus of claim 1 , wherein the second detector is a backscattered electron detector.

9. The charged particle optical apparatus of claim 1 , wherein the second detector is at ground potential and wherein a potential of the object is adjustable relative to ground potential.

10. The charged particle optical apparatus of claim 1 , further comprising a positioning mechanism configured to selectively position the common mounting structure such that the first detector and the second detector are in one of an operating position and a non-operating position,
wherein the plural collector electrodes are distributed around the primary particle beam path when the first detector and the second detector are in the operating position, and
wherein the first detector and the second detector are outside of the primary particle beam path when the common mounting structure is in the non-operating position.

11. The charged particle optical apparatus of claim 1 , further comprising a positioning mechanism configured to selectively position the differential pressure module into one of an operating position and a non-operating position,
wherein the particle beam path passes through the differential pressure aperture when the differential pressure module is in the operating position, and
wherein the differential pressure module is outside of the primary particle beam path when the differential pressure module is in the non-operating position.

12. The charged particle optical apparatus of claim 11 , wherein the differential pressure module comprises an intermediate vacuum zone, wherein the particle beam path passes through the intermediate vacuum zone when the differential pressure module is in the operating position of the differential pressure module.

13. The charged particle optical apparatus of claim 12 , wherein the differential pressure module comprises a first electrode and a second electrode, each providing a differential pressure aperture.

14. The charged particle optical apparatus of claim 12 , wherein the intermediate vacuum zone has a vacuum port for evacuating the intermediate vacuum zone.

15. A charged particle optical apparatus, comprising:
a particle optical arrangement, configured to define a primary particle beam path for inspecting an object;
a specimen chamber configured to accommodate an object in a pressure-controlled interior of the specimen chamber during the inspection of the object;
a differential pressure module having at least one differential pressure aperture;
a first detector, wherein the first detector is a gaseous detector; and
a second detector, wherein the second detector is a semiconductor detector having at least one particle receiving surface arranged circumferentially around the primary particle beam path;
wherein the first detector includes a collector electrode,
wherein the collector electrode extends around the primary particle beam path;
wherein the first detector and the second detector are mounted on a common mounting structure; and
wherein the collector electrode has an end portion closer to an interaction region than the at least one particle receiving surface, wherein the interaction region is a region where a primary particle beam generated by the particle optical apparatus interacts with the object during the inspection of the object.

16. The charged particle optical apparatus of claim 15 , further comprising a positioning mechanism configured to selectively position the common mounting structure such that the first detector and the second detector are in one of an operating position and a non-operating position,
wherein the at least one particle receiving surface is arranged circumferentially around the primary particle beam path when the first detector and the second detector are in the operating position, and
wherein the first detector and the second detector are outside of the primary particle beam path when the common mounting structure is in the non-operating position.

17. The charged particle optical apparatus of claim 15 , wherein the second detector is a backscattered electron detector.

18. The charged particle optical apparatus of claim 15 , wherein the second detector is at ground potential and wherein a potential of the object is adjustable relative to ground potential.

19. The charged particle optical apparatus of claim 15 , wherein the collector electrode provides a first differential pressure aperture of the least one differential pressure aperture.

20. The charged particle optical apparatus of claim 15 , wherein the collector electrode extends through a central opening provided by the at least one particle receiving surface.

21. The charged particle optical apparatus of claim 15 , wherein the collector electrode has a conical shape surrounding the primary particle beam path.

22. The charged particle optical apparatus of claim 15 , wherein the collector electrode has a base portion, wherein the at least one particle receiving surface is closer to the interaction region than the base portion.

23. The charged particle optical apparatus of claim 15 , wherein the at least one particle receiving surface includes plural particle receiving surfaces.

24. The charged particle optical apparatus of claim 23 , wherein a number of the plural particle receiving surfaces is four.

25. The charged particle optical apparatus of claim 15 , further comprising a positionin

Assignees

• Zeiss Carl Microscopy Gmbh

Inventors

• Essers Erik
• Albiez Michael
• Meyer Stefan
• Kirsten Daniel
• Bean Stewart

Classifications

• H01J37/244 Primary

  Detectors; Associated components or circuits therefor · CPC title

• H01J2237/24445

  using avalanche in a gas · CPC title

• H01J2237/188

  Differential pressure · CPC title

• H01J2237/2608

  with environmental specimen chamber · CPC title

• H01J2237/2448

  Secondary particle detectors · CPC title