Novolak resin design concept for high-resolution positive resists

摘要

Abstract: A new novolak-type photoresist which is applicable to excimer laser lithography has been developed. This resist consists of a naphthoquinonediazide-4-sulfonyl ester(NQD-4) and branched novolak resins, which are synthesized in an excess formalin/m-cresol molar ratio (1$APEQ@2) condition. The branched novolak resin-NQD-4 pendent resist (BNP resist) has about two times higher sensitivity than a conventional novolak resist (PR-1024MB) and exhibits clearly a surface development induction, which affords higher $gamma@-values. Copolymerization of hydroquinone (HQ) improves the sensitivity, resist profile, and mask linearity of the BNP resist. The BNP-HQ resist has a resolution capability of 0.35 $mu@m lines and spaces with a KrF excimer laser sensitivity of about 170 mJ/cm$+2$/. Therefore, our design concept of novolak resin is applicable to high resolution positive resists and especially to excimer resists.!