MOSFET fabrication technology | Fabrication of MOS devices
This page on MOSFET fabrication technology covers fabrication steps used in MOS devices such as MOSFET.
SiO2 layer formation: An SiO2 layer is constructed to form on
surface of the p-type Si-substrate by exposing top surface to the dry oxygen.
n+ layer diffusion: Two n+ layers are diffused into a p-region through two openings by using the photo-resist and UV ray technique.
Photoetching: The centre part Of SiO2 is removed by masking and photoetching method.
Re-oxidation: The total top surface of the final material is exposed to dry oxygen. Due to this, SiO2 layer is formed to completely cover the top surface.
Deposition: Phosphorous glass is deposited to cover the surface of SiO2.
Photoetching: By UV ray photoetching process, two windows are again opened on SiO2 layer above the n+ diffused regions.
Metallization: Entire Top surface of the device is metalized using Al material.
Masking and etching: By masking and photo-etching; Al metal contacts are retained to diffused gate, drain and source regions. The unwanted metal regions are etched away.
Figure above depicts fabrication process of NMOS type MOSFET.