Patent ID: 7018885

Claim:
A method of manufacturing semiconductor devices, comprising the steps of: forming a sacrificial oxide film on a semiconductor substrate; forming a triple well on the semiconductor substrate; implanting an ion of a heavy weight into a channel region of the semiconductor substrate to form an ion implantation layer; implanting an ion for adjusting a threshold voltage into the ion implantation layer; removing the sacrificial oxide film and then sequentially forming a tunnel oxide film, a polysilicon layer and a pad nitride film on the semiconductor substrate; patterning the pad nitride film by means of an isolation mask and then sequentially etching exposed portions of the polysilicon layer, the tunnel oxide film and the semiconductor substrate to form a trench; and forming an oxide film on the entire structure so that the trench is buried, planarizing the surface of the oxide film, and then removing remaining pad nitride film to form an isolation film within the trench.