IRREGULAR SURFACE AND POROUS STRUCTURE OF SIO2-FILMS DEPOSITED AT LOW-TEMPERATURE AND LOW-PRESSURE

The porous structure of silicon dioxide layers obtained by chemical va por deposition during monosilane oxidation by oxygen in the pressure r ange of 0.5-1.2 Torr at 150 degrees C has been studied by means of ads orption porometry. Mesopore size distribution has been found to be sha rply dependent on the pressure of the gas mixture at which the deposit ion is carried out. The specific surface area of the layers obtained a t different pressures has also been measured by means of the adsorptio n method. It has been stated that over the scale range of about 18-45 Angstrom(2) the surfaces of the layers obtained at 0.5 and 0.8 Torr ar e fractal. The fractal dimensions of the surface (D) have been determi ned to be 2.92 +/- 0.10 and 2.78 +/- 0.12, respectively, for the two g iven pressure values.