High quality low temperature DPECVD silicon dioxide

In this work we present the results on silicon dioxide films grown by the direct plasma enhanced chemical vapor deposition (DPECVD) technique at low temperature (< 400 degrees C). The films were obtained by decomposition of appropriate mixtures of silane and nitrous oxide under different deposition conditions and their optical and structural properties were analyzed through Fourier transform infrared spectroscopy and ellipsometry. The results demonstrate the feasibility of obtaining stoichiometric silicon dioxide thin films by DPECVD without traces (within the detection limits of the FTIR analysis) of OH, NH or SiH bonds, provided suitable deposition conditions are utilized. In particular we show that DPECVD combined with small silane flow and small deposition pressure is as effective as the techniques already reported in the literature, such as helium dilution or remote plasma CVD, in promoting the growth of stoichiometric films structurally similar to thermally grown silicon dioxide and having the added advantage of simplicity.