Positive photosensitive polyimide synthesized by block-copolymerization for KrF lithography

We have developed photosensitive polyimides synthesized by block-copolymerization for KrF lithography. The polyimides were synthesized from aliphatic tetracarboxylic dianhydrides and aliphatic diamines. Aliphatic rings have been introduced to reduce absorption at 248 nm (KrF). We have obtained line patterns of 0.17 micrometer at a dose of 170 mJ/cm2, and line and space patterns of 0.25 micrometer at a dose of 190 mJ/cm2.