There are a large number and variety of basic fabrication steps used in the production of modern MOS ICs. The same process can be used for the designed of NMOS or PMOS or CMOS devices.The gate material could be either metal or poly-silicon . The most commonly used substrate is bulk silicon or silicon-on-sapphire (SOS). Inorder to avoid the presence of parasitic transistors, variations are brought in the techniques that are used to isolate the devices in the wafer.
The fabrication steps are as follows: