These are the silicon wafers which have been through either a Wet Thermal Oxide, or a Dry Thermal Oxide process, to “grow” a Thermal Oxide, or Silicon Dioxide (Sio2), layer on the surface of the wafer. This is done by exposing the wafer to a combination of oxidizing agents and heat. The oxide is most commonly used as a dielectric layer and in MEMs devices. Thermal Oxide is grown on both sides of the wafer, but can then be removed from one side if a single side oxide layer is needed.