Patent ID: 9105439
Filing Date: 2015-08-11
Classification: B82Y,H01J

Abstract:
1. A charged particle optical system for exposing a target using a plurality of charged particle beamlets projected on the target without a common cross-over of all the beamlets, the system comprising: a beamlet generator for generating a plurality of charged particle beamlets; a beam blanker array comprising blankers for blanking one or more of the charged particle beamlets; a beam stop array comprising a substrate provided with an array of apertures, the diameter of the apertures of the beam stop array being such that, during operation, it determines the cross section of beamlets that pass through the apertures of the beam stop array; an electrostatic deflection system for scanning the charged particle beamlets over the target, the deflection system located downstream from the beam stop array; a projection lens arrangement for projecting the charged particle beamlets onto the target, the projection lens arrangement located downstream from the deflector array; wherein the electrostatic deflection system comprises a first electrostatic deflector and a second electrostatic deflector for scanning charged particle beamlets over the target, the second electrostatic deflector being located behind the first electrostatic deflector so that, during operation of the system, a beamlet generated by the beamlet generator passes both of the electrostatic deflectors; wherein, during operation of the first and second electrostatic deflectors, the system is adapted to apply voltages on the first electrostatic deflector and the second electrostatic deflector of opposite sign, and the voltages applied to the first and second deflectors are mutually changed in such a way that the pivot point of beamlets is in the optical plane of projection lens arrangement and the beamlets cross the optical axis the projection lens system; wherein the projection lens arrangement comprises first, second and third projection lens plates, each plate having a plurality of holes formed in it in an array and each plate having an electrode adapted to receive a common control voltage applied to each plate; and wherein the projection lens plates are adapted for forming an array of electrostatic projection lens systems at the location of the holes in the projection lens plates when control voltages are applied, each projection lens system comprising projection lenses formed at corresponding holes of the projection lens plates.