Patent ID: 8791425
Filing Date: 2014-07-29
Classification: B82Y,H01J

Abstract:
1. A multi-axis magnetic immersion objective lens, comprising: a pair of parallel magnetic conductor plates with a plurality of through round holes in pairs therein, the pair of parallel magnetic conductor plates including an upper plate and a lower plate, for each paired through round holes, an upper through round hole in the upper plate aligned with a corresponding lower through round hole in the lower plate; a plurality of magnetic rings inside and aligned with the plurality of through round holes with a plurality of pairs of an upper radial gap and a lower radial gap respectively, wherein for each magnetic ring in each paired through round holes, the upper and lower radial gaps are respectively between outer sidewall of said magnetic ring and inner sidewalls of the upper and lower through round holes respectively, thereby forming a plurality of magnetic sub-lens modules for focusing a plurality of charged particle beams respectively, wherein for each sub-lens module, the magnetic ring functions as an upper pole-piece and a portion forming the lower through round hole in the lower plate functions as an lower pole-piece; 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, wherein a first lower radial gap of the plurality of pairs of upper radial and lower radial gaps has a funnel shape with a narrow lower end opposite to an upper surface of the specimen.