Stochastic effects in fabrication of 11nm line-and-space patterns using extreme ultraviolet lithography

Abstract

The suppression of stochastic effects such as line edge roughness (LER) and stochastic defect generation is required for the realization of high volume production of semiconductor devices with 11 nm critical dimension using extreme ultraviolet (EUV) lithography. In this study, the effect of the molecular weight and protection ratio of the resist polymer on LER and stochastic defect generation was investigated. By increasing the molecular weight, LER and the probability for the stochastic defect generation were decreased. The negative effect caused by the increase of molecular weight is the increase of the minimum block size for dissolution in the development process. By increasing the protection ratio, the similar effect was expected. However, LER and the probability for the stochastic defect generation were not significantly decreased by increasing the protection ratio because of the decrease of quantum efficiency of acid generation caused by the protection of proton sources. The development of protecting group that does not affect the quantum efficiency is essential to decrease the stochastic effects.