STAGED DEVELOPMENT OF MODIFIED SILICON DIOXIDE FILMS

The hydrolytic generation of SiO2 films from chlorosilanes or alkoxysi lanes is interrupted by incorporating labile organic groups which stop SiO2 formation at a processable prepolymer stage. The monomers for th e prepolymer have electron withdrawing substituents in the beta-positi on. The organic groups are removed from the prepolymer at low temperat ure, extruding ethylene. The formation of SiO2 proceeds by intramolecu lar condensation of the electronegative substituents which are now in a hydrolytically unstable bond with silicon and hydroxyl groups or amb ient moisture. Films of the prepolymer spun onto silicon wafers are co nverted into uniform SiO2-rich films at temperatures between 150-400 d egrees C.