Effect of thermalization distance on chemical gradient of line-and-space patterns with 7 nm half-pitch in chemically amplified extreme ultraviolet resists

摘要

In the development of high-resolution chemically amplified resists used for extreme-ultraviolet (EUV) lithography, the thermalization distance of secondary electrons is a significant concern. In this study, the effects of thermalization distance on the chemical gradient of line-and-space patterns with 7 nm half-pitch were investigated on the basis of the sensitization mechanisms of chemically amplified EUV resists. For the acid generator concentration of 10 wt% and the sensitivity of 30 mJ cm(-2), the normalized chemical gradient monotonically increased when the thermalization distance decreased from 6 to 1 nm. For the acid generator concentration of 30 wt% and the sensitivity of 65 mJ cm(-2), the normalized chemical gradient had a peak value at the thermalization distance of 1.5 nm. It was found that the optimum thermalization distance in terms of normalized chemical gradient depended on the acid generator concentration and sensitivity. (C) 2015 The Japan Society of Applied Physics