Transmission measurements of pellicles for deep-UV lithography

Candidate deep-UV pellicle materials were tested for transmission stability under deep-UV exposure. Measurements were made with an exposure apparatus using a KrF excimer laser and a light pipe illuminator. Increased absorption and thickness reduction caused by deep-UV exposure were found in polyvinyl butyral (PVB)-based pellicles. The thickness of the PVB pellicles was monitored in situ, and a dark reaction was found to occur long after the deep-UV exposure is complete. Pellicles made with a second, fluoropolymer material were also tested and found to be stable up to exposures of 10000 J/cm/sup 2/.<
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