Multiple-beam and multiple-column exposure systems in maskless lithography tools are expected to significantly increase exposure throughput. However, the throughput performance obtained from a multiple-beam exposure system using vector writing did not improve as much as could be expected based on the number of beams. This is because the movement speed of a stage is determined by the maximum number of shots in each area to which multiple simultaneously emitted beams are deflected. We found that actual chips have a great variation in this number of shots, and that this variation halves the high throughput efficiency provided by multiple beams. Our proposed data processing system can provide high exposure throughput by controlling variations in the numbers of shots in the unit areas exposed to multiple beams emitted simultaneously, and suppresses these variations to an extremely low level. It succeeds in making throughput performance proportional to the number of beams by creating exposure data for the multiple-beam exposure system. (c) 2006 American Vacuum Society.