Oxidation Layering
Oxidation layering produces a thin layer of silicon dioxide, or oxide, on the substrate by exposing the wafer to a mixture of high-purity oxygen and hydrogen at 1000C (1800F).

Oxide is used to provide insulating and passivation layers and form transistor gates. Insulating oxide layers are usually about 1500 (angstroms). Gate layers are usually between 200 and 500 angstroms.