Formation of silicon oxide over gold layers on silicon substrates

When a single-crystal substrate of silicon is covered with evaporated gold and heated at relatively low temperatures (100–300°C) in an oxidizing atmosphere, a silicon-dioxide layer is readily formed over the gold layer. The mechanism and factors controlling this low-temperature oxide formation have been investigated using backscattering of 2-MeV He+ ions. The oxide layer is nonuniform in thickness and the initial growth of this layer is proportional to (time)1/2. Both oxidizing ambient and orientation of the substrate influence the growth rate, and the amount of gold determines the final thickness of oxide. A model is proposed to explain the oxide-growth mechanism.