Point Spread Function for the Calculation of Acid Distribution in Chemically Amplified Resists for Extreme Ultraviolet Lithography

The process simulator is a key technology in extreme ultraviolet (EUV) lithography, which is regarded as the ultimate in projection lithography. The requirement for the accuracy of process simulators has become increasingly strict with the shrinkage of feature size. In chemically amplified EUV resists, acid generators decompose through a reaction with thermalized electrons (~25 meV). This sensitization mechanism of EUV resists is analogous to that induced by an electron beam (EB). However, the acid distribution in EUV resists is different from that in EB resists because of the multispur effect, which is caused by the charged intermediates narrowly distributed around the absorption points of EUV photons. In this work, the authors formulate a proposed point spread function for the EUV lithography process based on chemically amplified resists.

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