Synthesis of cycloolefin maleic anhydride alternating copolymers for 193 nm imaging

A series of novel cycloolefin-maleic anhydride copolymers have been prepared and evaluated for 193 nm imaging applications. Free radical induced copolymerization of norbornene and maleic anhydride affords a hydrolytically robust alternating copolymer. Aqueous base solubility can be induced via incorporation of acrylic acid and/or acrylate esters that can be cleaved to afford the parent acid via acidolysis, The proportion of acrylate in the resulting terpolymers is a linear function of the starting monomer ratio. These terpolymers are thermally stable and hydrolytically robust. Due to their aqueous base solubility and UV transparency, they have potential in high resolution imaging applications. Sub-0.18 mu m imaging has been demonstrated upon 193 nm pattern-wise exposure of selected materials.