Semiconductor device having nanosheet transistor and methods of fabrication thereof

Abstract

Embodiments of the present disclosure provide a method for forming semiconductor device structures. The method includes forming a fin structure having a stack of semiconductor layers comprising first semiconductor layers and second semiconductor layers alternatingly arranged, forming a sacrificial gate structure over a portion of the fin structure, removing the first and second semiconductor layers in a source/drain region of the fin structure that is not covered by the sacrificial gate structure, forming an epitaxial source/drain feature in the source/drain region, removing portions of the sacrificial gate structure to expose the first and second semiconductor layers, removing portions of the second semiconductor layers so that at least one second semiconductor layer has a width less than a width of each of the first semiconductor layers, forming a conformal gate dielectric layer on exposed first and second semiconductor layers, and forming a gate electrode layer on the conformal gate dielectric layer.