Patent ID: 6989546

Claim:
An apparatus for multibeam lithography by means of electrically charged particles, comprising an illumination system having a particle source, the illumination system producing an illuminating beam of said electrically charged particles, and a multibeam optical system positioned after the illumination system as seen in the direction of the beam, said multibeam optical system comprising at least one aperture plate having an array of a plurality of apertures to form a plurality of sub-beams, wherein the multibeam optical system focuses the sub-beams onto the surface of a substrate, for simultaneously writing a plurality of different patterns, wherein, for each sub-beam, a deflection unit is provided, said deflection unit being adapted to correct individual imaging aberrations of the respective sub-beam with respect to the desired target position and position the sub-beam during a writing process on the substrate surface, for independently writing a pattern which is different from patterns of other sub-beams, and wherein, for each sub-beam, the respective aperture of the first of the at least one aperture plate defines the size and shape of the sub-beam cross-section and the multibeam optical system produces an image of said aperture on the substrate surface.