Effect of molecular weight and protection ratio on line edge roughness and stochastic defect generation in chemically amplified resist processes of extreme ultraviolet lithography

Abstract

The suppression of stochastic effects such as line edge roughness (LER) and stochastic defect generation is required for the high-volume production of semiconductor devices with 11 nm critical dimension using extreme ultraviolet (EUV) lithography. In this study, the effects of the molecular weight and protection ratio of a resist polymer on LER and stochastic defect generation were investigated, assuming line-and-space patterns with 11 nm half-pitch. By increasing the molecular weight, LER and the probability of stochastic defect generation were decreased. The negative effect caused by the increase of molecular weight is the increase of the minimum dissolution block size in the development process. By increasing the protection ratio, a similar effect was expected. However, LER and the probability of stochastic defect generation were not significantly decreased because of the decrease of the quantum efficiency of acid generation caused by the protection of proton sources. It is important to increase the protection ratio without decreasing the quantum efficiency of acid generation for the suppression of LER and stochastic defect generation.