Recently 157 nm was considered as the next wavelength for high-resolution photolithography. This technology required the development of new materials for reticle protection pellicles. Fluoropolymers, being virtually only polymeric materials that do not have significant light adsorption in vacuum ultraviolet (VUV) spectral range, are promising candidates for this application. However, it was demonstrated that the commercial fluoropolymers that are traditionally used for pellicles at 248 nm and 193 nm wavelengths have no mechanical integrity and rapidly burst under irradiation with 157 nm light. Indeed, the energy of incident photons in the VUV region is extremely high (10 times higher than that of infrared irradiation) and even diminutive (unavoidable) light adsorption by a pellicle will initiate photoinduced degradation process. When fluoropolymers are exposed to the high-energy irradiation, the induced degradation process always involves photo-generation of radical species as initial steps.
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