LOCOS

As of 2008 it was largely superseded by shallow trench isolation.

The main goal is to create a silicon oxide insulating structure that penetrates under the surface of the wafer, so that the Si-SiO2 interface occurs at a lower point than the rest of the silicon surface.

This cannot be easily achieved by etching field oxide.

Thermal oxidation of selected regions surrounding transistors is used instead.

For process design and analysis purposes, the oxidation of silicon surfaces can be modeled effectively using the Deal–Grove model.