Free-radical alternating copolymerization of a series of acyclic and cyclic alkenyl(di)silanes with sulfur dioxide has been investigated with a view toward the preparation of new sensitive electronbeam resists stable in oxygen plasmas. The acyclic (omega) - alkenylpentamethyldisilanes studied in this work are represented by a general formula H2C equals CH-(CH2)n-SiMe3-X-SiMe3, where X equals bond and n equals 1-4 compounds 1a to 1d, X equals O, n equals 3 for 2c, and X equals CH2, n equals 3 for 3c. The cyclic alkenyl(di)silanes had a general formula -CH2-CH equals CH-CH2-SiMe3-X-, where X equals bond (4a), -SiMe2- (4b), or -O-SiMe2 (4c). High molecular weight soluble copolymers were obtained from 1b, 1c, 4a, and 4b. Monomer 4c failed to copolymerize with SO2 even at -75 degree(s)C, and copolymers of 1a, 1d, 2c and 3c with SO2 were insoluble. Thermal and oxygen plasma stability data and solubility characteristics indicate that among the copolymers studied, poly(1b sulfone) exhibits an optimum combination of properties for lithographic applications. This was confirmed by lithographic tests in which grating structures having a pitch of less than 250 nm were fabricated using this copolymer as a sensitive, oxygen plasma stable e-beam resist.
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