The Reaction of AL with Vitreous Silica

The solid state chemical reaction between aluminum films and vitreous silicon dioxide substrates is reported. This reaction where aluminum reduces silicon dioxide to form elemental silicon and aluminum oxide is extensively used in the semiconductor industry to remove native SiO2 thin layers at ohmic contacts and to promote adhesion of aluminum to silica. Sorbed water vapor on silica is shown to interfere with the reaction reducing the adherence of aluminum to silica. The rate of penetration of the reaction into silicon dioxide was found to follow an Arrhenius relationship with an activation energy of 2.562 eV.