Detecting erosion in collector optics with plasma sources in extreme ultraviolet (EUV) lithography systems

摘要

An embodiment of the present invention includes a technique to detect erosion in an extreme ultra violet (EUV) source collector system. An initial impedance and a coating impedance of a multi-layer (ML) coating of the collector in one of an extreme ultra violet lithography (EUVL) stepper and an optical system are obtained at first and second time instants. A relation between the coating and initial impedances is generated. An erosion rate of the ML coating is determined based on the relation.