To meet market's demands for high performance devices, we have studied various resolution enhancement techniques (RET), such as off axis illumination, phase shift masks, optical proximity correction, resist thermal reflow, and chemical shrinkage process etc. RELACS (resolution enhancement lithography assisted by chemical shrink) is one of the most useful technology among chemical shrink processes. We have introduced KrF-RELACS process into mass production phase. However, in the case of ArF lithography, we are not able to be satisfied with shrinkage performance of conventional RELACS materials. To improve this matter, we paid attention to the chemically difference of side chain between KrF resist and ArF resist polymers.