CHEMICAL REACTIONS that take place:

• Si_(s) + O_2(g) → SiO_2(s)  dry oxidation
• Si_(s) + H₂O_(g) → SiO_2(s) + H_2(g)  wet oxidation (a nonreactive gas is passed through water at high temperature and water vapour is transported this way in the reactor)

• Silicon oxidises at room temperature, forming native oxide (thin layer of a few nanometers)
• The higher temperature (700-1000oC) is needed so that the oxygen atoms diffuse through the formed oxide thicker layers, in order to reach the silicon surface and react
• Diffusion constant of O is higher than diffusion constant of Si a reaction takes place at SiO₂/Si interface