Self-aligned punchthrough stop doping in bulk finFET by reflowing doped oxide

摘要

A technique relates to punchthrough stop (PTS) doping in bulk fin field effect transistors. Fins are formed on a substrate, and each pair of the fins has a fin pitch. Each of the fins has an undoped fin channel and a punchthrough stop doping region underneath the undoped fin channel. A narrow shallow trench isolation trench is formed between the fin pitch of the fins. A wide shallow trench isolation trench is formed at an outside edge of the fins. A doped layer fills the narrow shallow trench isolation trench and the wide shallow trench isolation trench. A vertical thickness of the doped layer in the narrow shallow trench isolation trench is greater than a vertical thickness of the wide shallow trench isolation trench.