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US 6,855,938 B2Granted
Objective lens for an electron microscopy system and electron microscopy system
AssigneeCarl Zeiss NTS GmbH
InventorsDirk Preikszas, Michael Steigerwald, Peter Hoffrogge, Peter Gnauck
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Abstract
An objective lens with magnetic and electrostatic focusing for an electron microscopy system is provided whose at least partially conical outer shape allows orienting an object to be imaged at a large angle range in respect of an electron beam, said objective lens exhibiting, at the same time, good optical parameters. This is enabled by a specific geometry of the lens elements. Furthermore, an examination for the simultaneous imaging and processing of an object is proposed which comprises, besides an electron microscopy system with the above-mentioned objective lens, also an ion beam processing system and an object support.
Claims51
An objective lens for an electron microscopy system with magnetic and electrostatic focusing for inspecting an object positionable in an object plane, comprising:
- a pole shoe arrangement for generating a focusing magnetic field, which pole shoe arrangement is substantially rotationally symmetric about an optical axis of the objective lens extending in a z-direction and comprises an inner pole shoe and an outer pole shoe, wherein a pole shoe gap is formed between the inner and outer pole shoes at a lowermost position in the z-direction of the inner pole shoe, the pole shoe gap including a gap spacing oriented in the z-direction between the outer pole shoe and the inner pole shoe;
- a coil body disposed in a space between the inner and the outer pole shoes;
- and
- an electrode arrangement for generating a focusing electrostatic field, which electrode arrangement is substantially rotationally symmetric about the optical axis and comprises a beam tube which extends along the optical axis through the inner pole shoe and has a lower end, and a terminal electrode disposed spaced apart from the lower end of the beam tube,
- wherein, in a region within at least 3 cm around the pole shoe gap, the following applies:
- the inner pole shoe tapers downwards over at least a section of the inner pole shoe and has there an outer cone angle χ with respect to the z-direction,
- the outer pole shoe extends conically downwards over at least a section of the outer pole shoe and has there an inner cone angle Δ and an outer cone angle α with respect to the z-direction, and
- the objective lens is configured to allow a working distance between the terminal electrode and the object plane smaller than 2 mm for electrons which pass through the beam tube at energies of about 30 keV, and
- wherein the following applies:
- 30°<α<35° and 10°<Δ−χ<14°,
- wherein
- α represents the outer cone angle of the outer pole shoe
- Δ represents the inner cone angle of the outer pole shoe and
- χ represents the outer cone angle of the inner pole shoe.
11 more elements
An objective lens for an electron microscopy system with magnetic and electrostatic focusing for inspecting an object positionable in an object plane, comprising:
- a pole shoe arrangement for generating a focusing magnetic field, which pole shoe arrangement is substantially rotationally symmetric about an optical axis of the objective lens extending in a z-direction and comprises an inner pole shoe and an outer pole shoe, wherein a pole shoe gap is formed between the inner and outer pole shoes at a lowermost position in the z-direction of the inner pole shoe, the pole shoe gap including a gap spacing oriented in the z-direction between the outer pole shoe and the inner pole shoe;
- a coil body disposed in a space between the inner and the outer pole shoes;
- and
- an electrode arrangement for generating a focusing electrostatic field, which electrode arrangement is substantially rotationally symmetric about the optical axis and comprises a beam tube which extends along the optical axis through the inner pole shoe and has a lower end, and a terminal electrode disposed spaced apart from the lower end of the beam tube,
- wherein the outer pole shoe is delimited on the outside substantially by a cone surface with respect to the z-direction, wherein the terminal electrode is delimited on the outside substantially by a cone surface with respect to the z-direction, and wherein the terminal electrode is magnetically coupled to the outer pole shoe with a gap therebetween, for reducing the magnetic field in the object plane.
2 more elements
An objective lens for an electron microscopy system with magnetic and electrostatic focusing for inspecting an object positionable in an object plane, comprising:
- a pole shoe arrangement for generating a focusing magnetic field, which pole shoe arrangement is substantially rotationally symmetric about an optical axis of the objective lens extending in a z-direction and comprises an inner pole shoe and an outer pole shoe, wherein a pole shoe gap is formed between the inner and outer pole shoes at a lowermost position in the z-direction of the inner pole shoe, the pole shoe gap including a gap spacing oriented in the z-direction between the outer pole shoe and the inner pole shoe;
- a coil body disposed in a space between the inner and the outer pole shoes;
- and
- an electrode arrangement for generating a focusing electrostatic field, which electrode arrangement is substantially rotationally symmetric about the optical axis and comprises a beam tube which extends along the optical axis through the inner pole shoe and has a lower end, and a terminal electrode disposed spaced apart from the lower end of the beam tube,
- wherein a distance between the lowermost position in the z-direction of the inner pole shoe and the lower end of the beam tube is larger than 9 mm.
2 more elements
An objective lens for an electron microscopy system with magnetic and electrostatic focusing for inspecting an object positionable in an object plane, comprising:
- a pole shoe arrangement for generating a focusing magnetic field, which pole shoe arrangement is substantially rotationally symmetric about an optical axis of the objective lens extending in a z-direction and comprises an inner pole shoe and an outer pole shoe, wherein a pole shoe gap is formed between the inner and outer pole shoes at a lowermost position in the z-direction of the inner pole shoe, the pole shoe gap including a gap spacing oriented in the z-direction between the outer pole shoe and the inner pole shoe;
- a coil body disposed in a space between the inner and the outer pole shoes;
- and
- an electrode arrangement for generating a focusing electrostatic field, which electrode arrangement is substantially rotationally symmetric about the optical axis and comprises a beam tube which extends along the optical axis through the inner pole shoe and has a lower end, and a terminal electrode disposed spaced apart from the lower end of the beam tube,
- wherein the outer pole shoe is delimited on the outside substantially by a cone surface with respect to the z-direction, wherein the terminal electrode is delimited on the outside substantially by a cone surface with respect to the z-direction, and wherein the terminal electrode is magnetically coupled to the outer pole shoe via a gap therebetween, said gap between the terminal electrode and the outer pole shoe channeling magnetic flux between the terminal electrode and the outer pole shoe and away from the object plane.
2 more elements
Dependencies are inferred from the claim text.