Oxidation

 

Thermal oxidation allows a thin layer of silicon dioxide to be formed on the surface of the wafer. The process involves putting the wafers through over 1000°C of heat with pure oxygen, resulting in a chemical reaction; enabling the forming of the layer in uniform thickness. The oxidising ambient may also contain several percent of Hydrochloric acid (HCl).

 

The chlorine removes metal ions that may occur in the oxide. Thermal oxide incorporates silicon consumed from the substrate and oxygen supplied from the ambient. The rate of oxide growth is often predicted by the Deal-Grove model.