METHOD AND APPARATUS FOR EXPOSURE

摘要

A projection optic system (PL) is heated by the irradiation with exposure light (L) from a lighting system (2) before a reticle (R) is set up on a reticle stage (14). The reticle is then placed on the reticle stage and irradiated. As a result, before a projection of the reticle pattern onto a wafer, the projection optic system is preheated to a saturation point at which the reticle pattern is actually exposed, so that the temperature change of the optic system is reduced during the actual exposure. Further, the preheating in the absence of the reticle reduces the storage of light energy in the reticle, thus reducing the thermal expansion of the reticle, the variation of such expansion and the distortion of the projected image.