INFRARED STUDIES OF ROOM-TEMPERATURE DEPOSITION OF HYDROGENATED SILICON-OXIDE FILMS IN RF MAGNETRON DISCHARGES

The properties of a-SiOx:H thin films deposited at low temperature (si milar to 50 degrees C) in a low energy magnetron rf plasma system with Ar/SiH4/O-2 gas mixtures are investigated. In the low pressure regime (about 5 mTorr reactive gases), the surface reaction dominates in the him formation process. As the partial pressure ratio (R(OS)) of oxyge n to silane increases, the Si-H related vibrational modes gradually di sappear, and the film becomes stoichiometric SiO2 for R(OS)greater tha n or equal to 1. High quality oxide film can be deposited due to the l ow pressure environment and the plasma promoted surface process. In th e high pressure regime (tens of mTorr) the deposited SiO2 films contai n fine particles (tens of nanometer in size) and are porous (15% void) due to the gas phase homogeneous reaction and aggregation. The infrar ed absorbance spectra with normal and oblique incidence imply differen t origins of the half width and the shoulder intensity of the 1070 cm( -1) Si-O(s) mode. In comparison with the low pressure dense films, the narrow half width of the high pressure film may be caused by the more ordered local structure which has a narrower distribution of bond ang le and length, while the large shoulder intensity may be dominated by the larger (fine particle size) scale disorder. (C) 1995 American Inst itute of Physics.