Patent ID: 8859983

Claim:
A method of exposing a field on a target by means of a plurality of charged particle beamlets, the method comprising: providing a target to be exposed, the target comprising the field; generating a plurality of charged particle beamlets, the beamlets being generated by one or more aperture arrays having apertures arranged in a plurality of groups, each group generating a plurality of the beamlets; blanking selected ones of the plurality of beamlets to define positions of exposing or not exposing the target by respective beamlets; creating relative movement in a first direction between the plurality of beamlets and the target; deflecting the groups of beamlets in a second direction simultaneously with the relative movement in the first direction such that each unblanked beamlet exposes a plurality of parallel scan lines on the target; wherein the relative movement in the first direction, the deflection of the plurality of beamlets in the second direction, and the arrangement of the apertures in the one or more apertures arrays, are such that the distance between adjacent parallel scan lines exposed by the unblanked beamlets of each group of beamlets is smaller than a pitch between beamlets from adjacent apertures of the aperture array which generated the group of beamlets.