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US 8,835,867 B2Granted
Multi-axis magnetic lens for focusing a plurality of charged particle beams
AssigneeHermes Microvision, Inc.
InventorsZhongwei Chen, Weiming Ren, Xuedong Liu
Life of this patent
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Abstract
A cellular-type PD unit is proposed and a plurality of the cellular-type PD units is used in pairs in a multi-axis magnetic lens for focusing a plurality of charged beams. First type PD units or second type PD units (called as hybrid PD unit as well) can be applied to cellular-type PD units to flexibly construct sub-lenses. Furthermore, magnetic shielding plates with a plurality of through openings can be placed above and/or below the multi-axis magnetic lens to make magnetic flux leaking out of the multi-axis magnetic lens vanish away rapidly outside the magnetic shielding plates.
Claims29
A multi-axis magnetic lens, comprising:
- a pair of parallel magnetic conductor plates with a plurality of through holes in pairs therein, the pair of parallel magnetic conductor plates including an upper plate and a lower plate, wherein for each paired through holes, an upper through hole in the upper plate is aligned with a corresponding lower through hole in the lower plate;
- a plurality of magnetic cellular pillars in pairs inside the plurality of through holes with a plurality of first radial gaps in pairs respectively, each pair of magnetic cellular pillars forming an axial gap therebetween and having a plurality of through bores in pairs, wherein for each paired first radial gaps formed by each paired magnetic cellular pillars inside each paired through holes, a first upper radial gap is between an inner sidewall of the upper through hole and an outer sidewall of the upper magnetic cellular pillar inside the upper through hole, a first lower radial gap is between an inner sidewall of the lower through hole and an outer sidewall of the lower magnetic cellular pillar inside the lower through hole, wherein for each paired through bores inside said each paired magnetic cellular pillars, an upper through bore in the upper magnetic cellular pillar is aligned with a corresponding lower through bore in the lower magnetic cellular pillar,
- thereby forming a plurality of magnetic sub-lens group modules for focusing a plurality of charged particle beams respectively, wherein each magnetic sub-lens group comprises a plurality of magnetic sub-lenses, and paired upper and lower magnetic cellular pillars of each sub-lens group module respectively function as upper and lower pole-pieces of each sub-lens of said sub-lens group;
- and
- a common excitation coil located between the pair of parallel magnetic conductor plates for providing magnetic flux to the plurality of magnetic sub-lens group modules.
2 more elements
A permeability-discontinuity unit, comprising:
- one magnetic cellular layer;
- and
- at least one non-magnetic or weakly-magnetic annular layer outside said magnetic cellular layer,
- wherein permeability of each weakly-magnetic annular layer is much smaller than that of said magnetic cellular layer.
1 more element
A permeability-discontinuity unit, comprising:
- one magnetic cellular layer;
- at least one magnetic annular layer;
- and
- at least one non-magnetic or weakly-magnetic annular layer,
- wherein one magnetic annular layer is immediately enclosed by one non-magnetic or weakly-magnetic annular layer and/or immediately encloses one non-magnetic or weakly-magnetic annular layer, the innermost annular layer encloses said magnetic cellular layer, and permeability of each weakly-magnetic annular layer is much smaller than that of said magnetic cellular layer and magnetic annular layers.
2 more elements
A magnetic shielding device for a multi-axis magnetic lens, comprising:
- at least one first magnetic shielding plate respectively having a plurality of first through openings and on one side of said multi-axis magnetic lens, wherein an optical axis of each magnetic sub-lens of said multi-axis magnetic lens is aligned with one of said first through openings of said each first magnetic shielding plate,
- wherein all said first magnetic shielding plates are configured to make magnetic flux leaking out of said multi-axis magnetic lens vanish away rapidly outside the magnetic shielding device.
A multi-axis magnetic lens, comprising:
- a pair of parallel magnetic conductor plates with a plurality of through holes in pairs therein, the pair of parallel magnetic conductor plates including an upper plate and a lower plate, wherein for each paired through holes, an upper through hole in the upper plate is aligned with a corresponding lower through hole in the lower plate;
- a plurality of magnetic pillars in pairs inside the plurality of through holes with a plurality of first radial gaps in pairs respectively, each pair of magnetic pillars forming an axial gap therebetween and having a pair of through bores, wherein for each paired first radial gaps formed by each paired magnetic pillars inside each paired through holes, a first upper radial gap is between an inner sidewall of the upper through hole and an outer sidewall of the upper magnetic pillar inside the upper through hole, a first lower radial gap is between an inner sidewall of the lower through hole and an outer sidewall of the lower magnetic pillar inside the lower through hole, wherein for one paired through bores inside said each paired magnetic pillars, an upper through bore in the upper magnetic pillar is aligned with a lower through bore in the lower magnetic pillar and said upper through bore is off from a center of said upper magnetic pillar,
- thereby forming a plurality of magnetic sub-lens modules for focusing a plurality of charged particle beams respectively, wherein paired upper and lower magnetic pillars of each sub-lens module respectively function as upper and lower pole-pieces of said sub-lens;
- and
- a common excitation coil located between the pair of parallel magnetic conductor plates for providing magnetic flux to the plurality of magnetic sub-lens modules.
2 more elements
Dependencies are inferred from the claim text.