ENHANCED SIO2 FORMATION AT EXPOSED POLYMER SURFACE BY CVD METHOD

Copolymers of t-butyl methacrylate (TBMA) and 9-fluorenilideneimino p- styrenesulfonate (FIS) were prepared. Upon irradiation at 254 nm, FIS units of the polymers became p-styrenesulfonic acid units. When the ir radiated polymer was heated at 140 degrees C, the acid-catalyzed deest erification of TBMA units occurred to form methacrylic acid units. Whe n the surface of the film composed of p-styrenesulfonic acid and metha crylic acid units was exposed to the vapor of tetramethoxysilane at 30 degrees C, SiO2 was formed at the surface. No SiO2 formation was obse rved for the unirradiated films or for irradiated films without subseq uent heating. The SiO2 formation rate was strongly affected by the amo unts of p-styrenesulfonic acid units formed photochemically and the ty pe of alkoxysilanes used. The surface modified with SiO2 showed a good resistance to the etching using an oxygen plasma. A negative-tone ima ge was performed using this system. (C) 1998 Elsevier Science Ltd. All rights reserved.