Theoretical study on defect risks of chemically amplified resists used for extreme ultraviolet lithography

Abstract

Abstract In lithography, resist patterns are fabricated through chemical reactions induced by radiation. In the highly resolving lithography such as extreme ultraviolet (EUV) lithography, the stochastically generated defects (stochastic defects) are a serious concern. In this study, the variation of resist polymer caused by stochastic effects was investigated, assuming line-and-space resist patterns to assess the defect risks. Using a half pitch HP, a thermalization distance r 0, a total sensitizer concentration C s, and an initial standard deviation of the number of protected units per polymer molecule σ i as variables, the resist pattern formation was simulated on the basis of the reaction mechanisms of chemically amplified EUV resists. The frequency distribution of polymer molecules with the given number of protected units was calculated at the centers of lines and spaces. By defining a total defect risk (the sum of pinching and bridging risks), its dependences on HP, r 0, C s, and σ i were clarified.