Abstract: “VLSI stands for “Very Large Scale Integration, which is the capability of semiconductor to fabricate many MOS family transistor into single silicon chip. CMOS is referred as “Complementary Metal Oxide Semiconductor” which is the technology of fabricating the n-type and p-type MOSFETs side by side on the same silicon substrate to construct a VLSI circuit. It has capability of developing both digital as well as analogue based applications. There are three types of materials used to design CMOS VLSI circuits. They are insulator, conductors and semiconductors. The paper also enlightens the fabrication process sequence which involves following steps silicon manufacture, wafer processing, lithography, oxidation, diffusion, ion implantation,deposition, metallization, testing and packing. The main advantages of this technology are CMOS possess very high input impedance and the outputs are significantly high. The VLSI Technology is currently a booming technology which has changed the electronic world.”