Dielectric Punch-Through Stoppers for Forming FinFETs Having Dual Fin Heights

摘要

A semiconductor structure includes a semiconductor substrate having a first portion and a second portion. A first Fin field-effect transistor (FinFET) is formed over the first portion of the semiconductor substrate, wherein the first FinFET includes a first fin having a first fin height. A second FinFET is formed over the second portion of the semiconductor substrate, wherein the second FinFET includes a second fin having a second fin height different from the first fin height. A top surface of the first fin is substantially level with a top surface of the second fin. A punch-through stopper is underlying and adjoining the first FinFET, wherein the punch-through stopper isolates the first fin from the first portion of the semiconductor substrate.

主权项

1. A method comprising:
forming isolation regions in a semiconductor substrate, with a portion of the semiconductor substrate being located between opposite portions of the isolation regions to form a first active region; removing top portions of the isolation regions to expose sidewalls of the first active region; forming a hard mask to cover a top surface and the sidewalls of the first active region; recessing the opposite portions of the isolation regions to expose an intermediate portion of the first active region, with the intermediate portion of the first active region being lower than a bottom surface of the hard mask; and oxidizing the intermediate portion of the first active region to form a punch-through stopper.