The trade-off relationships between resolution, sensitivity, and line edge roughness have become a serious problem in device manufacturing as the minimum feature size is reduced. To solve this problem, the improvement of pattern formation efficiency is necessary. The efficiency of pattern formation is mainly determined by the efficiencies of incident radiation absorption, acid generation, and deprotection. The deprotection efficiency is the number of times an acid can induce catalytic reactions during the diffusion of a unit distance. The highest expected deprotection efficiency is achieved by a diffusion-controlled reaction. In this study, the authors investigated the feasibility of low-E-a resists for 22 nm fabrication. It was found that their efficiency is inadequate for 22 nm fine patterning even when a diffusion-controlled rate is assumed. For 22 nm fabrication with 5-10 mJ cm(-2) exposure dose, increases in acid generation efficiency and polymer absorption are essential.