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 curved surface to compensate for landing angle dependent distortions of the focussing electric field caused by the specimen.
1 Assignment
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Accused Products
Abstract
The present invention relates to a focussing lens (100) for focussing a charged particle beam (7) onto a specimen (3) at a predetermined landing angle (42; 42′; 42) comprising at least one first electrode (26, 105, 105a) having a first aperture (106) to generate a focussing electric field (110) for focussing the charged particle beam (7) onto the specimen (3); and a correcting electrode having a curved surface (115) to compensate for landing angle dependent distortions of the focussing electric field (110) caused by the specimen (3). With the curved surface (115) 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.
25 Citations
38 Claims
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1. A focussing lens for focussing a charged particle beam onto a specimen at a predetermined landing angle comprising:
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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 curved surface to compensate for landing angle dependent distortions of the focussing electric field caused by the specimen. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A charged particle beam device to inspect or structure a specimen at various predetermined landing angles comprising:
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a charged particle beam source to generate a charged particle beam;
a focussing lens to focus the charged particle beam onto the specimen, the focussing lens comprises 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 curved surface to compensate for landing angle dependent distortions of the focussing electric field caused by the specimen. - View Dependent Claims (22, 23, 24, 25)
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26. A method of inspecting or structuring a specimen by means of a charged particle beam at different landing angles including the steps:
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providing a charged particle beam device having a correcting electrode;
inspecting or structuring the specimen at a first landing angle at a first correcting electrode voltage applied to the correcting electrode; and
inspecting or structuring the specimen at a second landing angle at a second correcting electrode voltage applied to the correcting electrode.
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27. A method of inspecting or structuring a specimen by means of a charged particle beam at different landing angles including the steps:
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providing a charged particle beam device having a first electrode and a correcting electrode;
inspecting or structuring the specimen at a first landing angle with the correcting electrode at a first position with respect to the at least first electrode; and
inspecting or structuring the specimen at a second landing angle with the correcting electrode at a second position with respect to the at least first electrode. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35)
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36. A focussing lens for focussing a charged particle beam onto a specimen at a predetermined landing angle comprising:
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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 caused by the specimen, whereby the cone-like shaped curved surface of the correcting electrode has an opening on one side to provide space for the specimen to approach the first electrode.
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37. A method of inspecting or structuring a specimen by means of a charged particle beam at different landing angles including the steps:
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providing a charged particle beam device having a first electrode having a first electrode voltage V1, and a correcting electrode;
providing a specimen having a specimen voltage Vs;
inspecting or structuring the specimen at a first landing angle at a first correcting electrode voltage applied to the correcting electrode; and
inspecting or structuring the specimen at a second landing angle at a second correcting electrode voltage applied to the correcting electrode, whereby the second correcting electrode voltage is adjusted to a voltage given by 2*Vs−
V1 with a tolerance of less than 50 percent.
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38. A method of inspecting or structuring a specimen by means of a charged particle beam at different landing angles including the steps:
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providing a charged particle beam device having a first electrode having a first electrode voltage V1, and a correcting electrode;
providing a specimen having a specimen voltage Vs;
inspecting or structuring the specimen at a first landing angle with the correcting electrode at a first position with respect to the at least first electrode; and
inspecting or structuring the specimen at a second landing angle with the correcting electrode at a second position with respect to the at least first electrode, whereby the second correcting electrode voltage is adjusted to a voltage given by 2*Vs−
V1 with a tolerance of less than 50 percent.
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Specification