3d high density self-aligned nanosheet device formation with efficient layout and design

Abstract

A method of microfabrication includes forming an initial stack of semiconductor layers by epitaxial growth over a substrate. The initial stack of semiconductor layers is surrounded by a sidewall structure. The initial stack of semiconductor layers includes channel structures and sacrificial gate layers stacked alternatingly in a vertical direction substantially perpendicular to a working surface of the substrate. The channel structures include a first channel structure and a second channel structure positioned above the first channel structure. First portions of the sidewall structure are removed to uncover first sides of the initial stack. Source/drain (S/D) regions are formed on uncovered side surfaces of the channel structures from the first sides of the initial stack. Second portions of the sidewall structure are removed to uncover second sides of the initial stack. The sacrificial gate layers are replaced with gate structures from the second sides of the initial stack.