Focussing lens for charged particle beams
First Claim
1. A focussing lens for focussing a charged particle beam onto a specimen at a predetermined landing angle, comprising:
- at least a first electrode having a first aperture to generate a focussing electric field for focussing the charged particle beam onto the specimen; and
a correcting electrode having a cone-like shaped curved surface to compensate for landing angle dependent distortions of the focussing electric field, the distortions being caused by the specimen, wherein the cone-like shaped curved surface of the correcting electrode has an opening on a lateral surface between a base and an apex of the cone-like shaped surface to provide space for the specimen to approach the first electrode.
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Accused Products
Abstract
A focussing lens for focussing a charged particle beam onto a specimen at a predetermined landing angle. The focussing lens comprises at least one first electrode having a first aperture to generate a focussing electric field for focussing the charged particle beam onto the specimen and a correcting electrode having a curved surface to compensate for landing angle dependent distortions of the focussing electric field caused by the specimen. With the curved surface of the correcting electrode, it is possible to improve the focussing of a charged particle beam at landing angles that differ from the perpendicular landing angle.
32 Citations
23 Claims
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1. A focussing lens for focussing a charged particle beam onto a specimen at a predetermined landing angle, comprising:
- at least a first electrode having a first aperture to generate a focussing electric field for focussing the charged particle beam onto the specimen; and
a correcting electrode having a cone-like shaped curved surface to compensate for landing angle dependent distortions of the focussing electric field, the distortions being caused by the specimen, wherein the cone-like shaped curved surface of the correcting electrode has an opening on a lateral surface between a base and an apex of the cone-like shaped surface to provide space for the specimen to approach the first electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
- at least a first electrode having a first aperture to generate a focussing electric field for focussing the charged particle beam onto the specimen; and
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19. A charged particle beam device to inspect or structure a specimen at various predetermined landing angles, comprising:
- a charged particle beam source to generate a charged particle beam; and
a focussing lens to focus the charged particle beam onto the specimen, the focussing lens comprising at least a first electrode having a first aperture to generate a focussing electric field for focussing the charged particle beam onto the specimen and a correcting electrode having a cone-like shaped curved surface to compensate for landing angle dependent distortions of the focussing electric field, the distortions being caused by the specimen, wherein the cone-like shaped curved surface of the correcting electrode has an opening on a lateral surface between a base and an apex of the cone-like shaped surface to provide space for the specimen to approach the first electrode. - View Dependent Claims (20, 21, 22, 23)
- a charged particle beam source to generate a charged particle beam; and
Specification