In the field of semiconductor production using charged particle beam lithography, a method and system for fracturing or mask data preparation or proximity effect correction is disclosed, where a non-circular target pattern to be formed on a surface is input. A plurality of charged particle beam shots for a multi-beam charged particle beam system is determined, where the plurality of shots will form a pattern on the surface, each charged particle beam shot being a multi-beam shot comprising a plurality of circular or nearly-circular beamlets. The pattern on the surface matches the target pattern within a predetermined tolerance. The determining is performed using a computing hardware device.