Particle-optical projection system

A particle-optical projection system for imaging a pattern onto a target by means of energetic electrically charged particles in a particle-beam exposure apparatus, adapted to produce, from the pattern positioned at an object plane and represented in a patterned beam of said charged particles emerging from the object plane through at least one cross-over, an image of the pattern at the position of the target, with said image having a given size and distortion, said projection system comprising a multi-beam pattern definition means for defining the patterned beam with a time-variable pattern, having

• an aperture array means having a plurality of apertures defining the shape of beamlets permeating said apertures and
• at least one deflector array means separate from the aperture array means, with said deflector array means having a plurality of openings surrounding the beamlets, wherein for each opening or group of openings are provided at least two deflecting electrodes to which different electrostatic potentials are applicable, thus correcting the path of the beamlet passing through the respective opening according to a desired path through the device,
• wherein at least one of said deflector array means is adapted to adjust the angles of the beamlets passing the apertures to minimize the aberration of the crossover.