Development of 157 nm positive resists

Abstract

For adequate transparency we have selected hexafluoroisopropanol as an acid group and an α-trifluoromethylacrylic moiety as a repeat unit of our 157 nm resist polymers. The hexafluoroalcohol group is bound to norbornene or styrene. Four platforms are currently available to us: (1) all-acrylic, (2) all-alicyclic, (3) acrylic-alicyclic, and (4) acrylic-aromatic systems. While the all-alicyclic (all-norbornene) polymers are synthesized by transition-metal-initiated addition polymerization, all other polymers involving α-trifluoromethylacrylic monomers are prepared by conventional radical copolymerization. Characterization of the polymers and preliminary lithographic evaluation are reported.