POROUS STRUCTURE OF SILICA FILMS OBTAINED BY MONOSILANE OXIDATION

The porous structure of silica films obtained by monosilane oxidation by oxygen in an isothermal reactor in the temperature ran 150-250 degr ees C and pressure 0.5-1.2 Torr has been investigated by means of adso rption porometry. It has been found that at T< 200 degrees C the minim um radius of registered pores increases sharply when the pressure in t he reactor is : Increased. It is assumed, on the basis of experimental data, that tile elevation of pressure causes the increase in size of polymeric particles formed in the gas phase (clusters) that determine the size of the formed pores. At T > 200 degrees C, the minimum pore r adius in the films is weakly dependent on pressure; besides, the film density increases during its growth due to solid-phase reactions withi n tile bulk of the film. The mechanisms of the influence of gas-phase stages of monosilane oxidation on the regularities of mesopore formati on at deposition temperature within 150-200 degrees C is discussed, as well as the possibility of obtaining layers with a required porosity. (C) 1998 Elsevier Science S.A.