Silicon oxynitride material and photochemical process for forming same

A low temperature photochemical vapor deposition process for depositing a homogeneously chemically bonded silicon oxynitride material on the surface of a selected substrate comprising the steps of:

• (a) providing said substrate in a photochemical vapor deposition chamber;
• (b) reducing the pressure in said chamber to a pressure of about 0.1 to 50 torr;
• (c) forming a vapor phase mixture comprising ammonia (NH.sub.3) and silane (SiH.sub.4) and mercury vapors as a photosensitizer;
• and
• (d) exposing said substrate in said chamber to said vapor phase mixture and simultaneously introducing into said chamber radiation of a wavelength sufficient to induce the photochemical reaction of said ammonia with said silane and ambient oxygen in said chamber at said pressure, to form said silicon oxynitride material which deposits on said surface of said substrate, wherein the ratio of said ammonia to said silane and the flow rate of said silane are sufficient to limit the concentration of said silane such that substantially all excess said silane reacts with said oxygen to chemically bond silicon from said excess silane into said silicon oxynitride material, to thereby provide a silicon oxynitride material that is homogeneously chemically bonded and contains substantially no free amorphous silicon.

A silicon oxynitride material characterized by being homogeneously chemically bonded, containing minimal free amorphous silicon, and having a refractive index within the range of about 1.7 to 1.8 formed by a photochemical vapor deposition process comprising the steps of:

• (a) providing a selected substrate in a photochemical vapor deposition chamber;
• (b) forming a vapor phase mixture comprising ammonia and silane in the ratio of 80:1 or higher, mercury-vapors as a sensitizer for the desired photochemical reaction, and oxygen;
• and
• (c) exposing said substrate to said vapor phase mixture and simultaneously introducing into said chamber radiation of a predetermined wavelength sufficient to induce said photochemical reaction between said silane, said ammonia, and said oxygen to form said silicon oxynitride material which deposits on the surface of said substrate, wherein said oxygen is in an amount which reacts with any excess said silane and chemically bonds silicon from said excess silane into said silicon oxynitride material, to thereby prevent formation of said free amorphous silicon from said silane and heterogeneous incorporation of said free amorphous silicon into said silicon oxynitride material.