The formation of thin films of silica by the electron bombardment of triphenylsilanol

Abstract

Thin films of silica up to 800 A thick on germanium substrates have been produced by the electron bombardment of an evaporated thin film of triphenylsilanol. The resulting polymer film was oxidized in air at 500°C to form a layer of amorphous silica. The quantity governing the degree of polymerization was the product of current density and time, or exposure. For exposures of 3 × 10-3 C cm-2 or less, no continuous polymer film was obtained; above this value films were continuous in the lower thickness range of the silanol films, while with increasing exposure films up to 5500 A became continuous. The continuous polymer films became thicker with increasing exposure up to a maximum equal to the original silanol thickness, at about 11 × 10-3 C cm-2. The thickness of the silica layer increased with that of the polymer in the range 1000 to 4500 A. As a diffusion mask for germanium, the silica layers were effective against antimony, but permeable to indium diffusion.