Polysilicon deposition is carried out and gate definition is then completed using the mask shown in fig (c). Note that the connection between two gate inputs in a CMOS inverter is achieved using the poly silicon. The source and drain diffusions for pMOS is carried out using p-type diffusion. Boron is the most popular element used for this step. Similarly, source and drain diffusions for nMOS is carried out using n-type diffusion. Phosphorous and Arsenic can both be used for this step. Additional oxide is created, and then the contact holes are cut in the oxide down to the diffusions and polysilicon. These contacts can be filled by metal permitted to flow into the holes. The drains of pMOS and nMOS transistors are connected by a metal line in order to take the output from the CMOS inverter.

Fig 66 (c) : Top view of Poly silicon mask