device for compensating transient thermal strain of a photolithographiespiegels

摘要

An apparatus and method of maintaining a time-constant heat load on a lithography mirror (100). The mirror includes a resistive layer (107) formed on a substrate, contacts for coupling a power supply to the resistive layer (107), an insulating sublayer (105) formed on the resistive layer (107), a polished layer (117) formed on the insulating layer, and a reflective layer (119) formed on the polished layer (117). The time-constant heat load on the lithography mirror is maintained by placing an additional electrical heat load on the mirror according to the actinic heat load transmitted by the mask. Maintaining the time-constant heat load can reduce or eliminate variation in image distortion that occurs as a result of changes in actinic heat load on the lithography mirror. Independent temperature control can be used to mitigate "cold-edge effect." IMAGE