GeO2and SiO2thin film preparation with CVD using ultraviolet excimer lamps

We have prepared SiO2and GeO2thin films from tetraethoxyorthosilicate (TEOS; Si(OC2H5)4) and tetraethoxyorthogermanate (TEOG: Ge(OC2H5)4), respectively, by chemical vapor deposition (CVD) assisted by high-energy photons. The photons are supplied from excimer lamps which emit incoherent light at 308 (XeCl), 222 (KrCl), 172 (Xe2), 146 (Kr2) and 126 nm (Ar2). GeO2film deposition is observed for all excimer lamps used here, but SiO2films are obtained at wavelengths shorter than 172 nm. This is caused by a fact that the bonding energy between Si and O is much higher than that between Ge and O. The deposition rate is around 8nm/min for SiO2and 16nm/min for GeO2films. The film deposition rate increases with increasing the light intensity and with decreasing substrate temperature.