REDUCTION OF WATER IN INORGANIC SPIN ON GLASS

Water absorption characteristics of an inorganic spin on glass (SOG) are investigated. The weight of inorganic SOG film baked at 200-degrees-C is about 35% retained water. Baking the SOG film at 200-degrees-C and then at 450-degrees-C in N2 for 30 min leaves 20% water in the film. Oxygen plasma treatments such as ashing or sputter etching on 450-degrees-C-baked SOG films generally decrease the water content in the film. These treatments decrease the chemically adsorbed water, but increase the physically adsorbed water. We surmise that the energetic particles in the plasma eliminate the -OH group and at the same time deform the Si-O-Si framework structure, both resulting in water adsorption at the surface layer of the SOG film (physically adsorbed water). An oxygen plasma treatment in a parallel electrode reactor using a graphite susceptor drastically decreases the water content in the SOG film and reduces water adsorption during immersion in water. This treatment is called reactive glass stabilization (RGS). It is also found that the incorporation of organic material, which reduces the SOG water adsorption, is enhanced by the immersion of the RGS-treated SOG film in organic solutions.