Patent ID: 8368015
Filing Date: 2013-02-05
Classification: B82Y,H01J

Abstract:
1. A multi-beamlet multi-column particle-optical system comprising a plurality of particle-optical multi-beamlet columns, the plurality of particle-optical multi-beamlet columns being disposed in an array for simultaneously exposing a same substrate; with each particle optical column having an optical axis and comprising: a beamlet generating arrangement comprising at least one multi-aperture plate having a plurality of apertures for generating a pattern of multiple beamlets of charged particles, and an electrostatic lens arrangement downstream of the beamlet generating arrangement, the electrostatic lens arrangement comprising at least one electrode element, the at least one electrode element having an aperture allowing the generated multiple beamlets of charged particles to pass through, the aperture being defined by an inner peripheral edge facing the optical axis, the aperture having a centre and a predetermined shape in a plane orthogonal to the optical axis; wherein in at least one of the plurality of charged particle columns, the predetermined shape of the aperture of the at least one electrode element is a non-circular shape with at least one of a protrusion and an indentation from an ideal circle about the centre of the aperture, and wherein a first distance between a point on the inner peripheral edge of the aperture disposed closest to the centre of the aperture is at least about 5% smaller than a second distance between a point on the inner peripheral edge of the aperture disposed furthest away from the centre of the aperture.