Nanosheet device with tri-layer bottom dielectric isolation

Abstract

A nanosheet device includes a bottom dielectric isolation formed by a first portion of a high-k dielectric layer above a semiconductor substrate, a spacer material above the first portion of the high-k dielectric layer and a second portion of the high-k dielectric layer above the spacer material. A sequence of semiconductor channel layers are stacked perpendicularly to the semiconductor substrate above the bottom dielectric isolation and are separated by and vertically aligned with a metal gate stack. Source/drain regions extend laterally from opposite ends of the semiconductor channel layers with a bottom surface of the source/drain regions being in direct contact with the bottom dielectric isolation for electrically isolating the source/drain regions from the semiconductor substrate.