3.A Measuring Chemically Induced Optical Degradation in Dielectric Thin Films

Plasma-induced etching of dielectric thin films is widely used in ~ntegratedcircuit preparation technology. It normally involves the interaction of gas discharge species with a thin-film surface in order to produce volat~le reaction products. The ultimate goal is to etch through a frlm in a spatially selective manner and to thereby generate a desired pattern. This process also occurs unintentionally in the technology related to excimer lasers and fusion reactors. Unintentional etching effects are encountered when dielectric thin films, whose purpose is to establish an optical-interference multilayer stack, are exposed to electrons and ions from the excitat~on region of excimer gas-lasers. In the same vein, optical coatings that are part of laser-based, nuclear-fuel-reprocessing safeguard monitors and are in direct contact with streams of UF6 are subject to etching.