Photoinduced transformation of polysiloxane layers by SiO2

Polysiloxane layers deposited from the gas phase were transformed to pure SiO2 by a combined thermal/photolytical treatment. These experiments were performed with a mercury lamp under an O2 and N2O atmosphere. The kinetics were investigated by FTIR spectroscopy. The transformation of polysiloxane to SiO2 proceeds in two steps: the substitution of the organic radicales by OH groups (hydrolysis) and the subsequent formation of the SiO2 network (polycondensation). By this treatment at relatively low temperatures high quality SiO2 layers may be produced.