Gate-all-around field-effect transistor devices having source/drain extension contacts to channel layers for reduced parasitic resistance

Abstract

Devices and methods are provided for fabricating field-effect transistors having source/drain extension contacts to provide reduced parasitic resistance in electrical paths between source/drain layers and active channel layers surrounded by gate structures of the field-effect transistor devices. For example, in a nanosheet field-effect transistor device having embedded gate sidewall spacers which are disposed between end portions of active nanosheet channel layers and serve to insulate source/drain layers from a metal gate structure, epitaxial source/drain extension contacts are disposed between the embedded gate sidewall spacers and active nanosheet channel layers, and on sidewall surfaces of the active nanosheet channel layers. Epitaxial source/drain layers are grown starting on exposed surfaces of the epitaxial source/drain extension contacts. The epitaxial source/drain extension contacts laterally extend from epitaxial source/drain layers to a high-k dielectric/metal gate structure that surrounds the active nanosheet channel layers.