Progress in ArF single-layer resists

We have developed chemically amplified resists with adamantylmethacrylate, which have good dry-etch resistance for 193 nm lithography. Our resist system based on 2-methyl-2-adamantylmethacrylate (2MAdMA)-mevalonic lactone methacrylate (MLMA) 1:1 copolymer, had particularly high resolution, high sensitivity and good dry-etch resistance. We achieved minimal resolution below 150 nm using a Nikon ArF exposure system with NA of 0.55. However, our resists could not obtain fine patterns consistently below 150 nm and we need to achieve good repeatability in order to apply them to LSI production. To obtain stable repeatability in resist performance, we focused on controlling the molecular weight of our resin and on reducing the environmental effect of using base compounds. Furthermore, we proposed optional materials to achieve higher sensitivity.