New thermally crosslinkable electron-beam resists: 1. Itaconic anhydride-methyl methacrylate copolymers

This paper describes the lithographic evaluation of copolymers of itaconic anhydride (IT.ANH) and methyl methacrylate (MMA) as thermally crosslinkable electron-beam resists. Their properties were investigated as a function of copolymer composition and primary number-average molecular weight in order to determine an optimum formulation for the preparation of high-resolution resist patterns. Line and space test patterns with features smaller than 0.5 µm have been prepared using a copolymer containing 46 mol% IT.ANH with M_n = 5.30 × 10⁵ g mol^-1, which was thermally crosslinked by pre-baking at 170°C for 1 h. The electron exposure dose required to solubilise the resist (a_D) has been shown to be very much less than the exposure dose required for the preparation of high-resolution resist patterns. © 1991.