Performance of positive-tone chemically amplified resists for next-generation photomask fabrication

Abstract

Several types of chemically amplified resists (CARs) have been evaluated in comparison with other types of resists. The evaluated CARs were found to have better performance than conventional resists and to satisfy the requirements for next generation reticle fabrication. Especially CARs have high sensitivity and high contrast enough to make photomasks with e-beam writers and have good dry-etch durability. We evaluated the allowance of baking conditions. It was found that it was important to minimize the dependence on prebake temperature as well as on post exposure bake temperature. The influence of airborne contaminants on post exposure delay (PED) stability of CARs was investigated. PED stability depends on resist materials and the ammonia concentration in the process environment. The use of a chemical filter is effective in improving PED stability. In conclusion, CARs can meet the requirements for resists used for next generation reticle fabrication.