EXPOSURE CONTROLOLER FOR SOR DEVICE

摘要

PURPOSE:To enable exposure with the amount maintained substantially constant in a exposure device using SOR beam. CONSTITUTION:The exposure amount of SOR beam 29 is proportional to the product of storage current value and exposure time. Electron beams 42 circulating in a storage ring 22 disapear gradually with time, and accordingly the storage current value I decreases gradually. Exposure time for specified exposure amount is determined by an exposure time calculation means 39 according to the storage current value. An exposure control means 40 controls the exposure time of stepper in an exposure device 28 per one step to the determined exposure time. In this way uniform exposure is carried out.