Nanoribbon sub-fin isolation by backside si substrate removal etch selective to source and drain epitaxy

Abstract

Gate-all-around integrated circuit structures having nanoribbon sub-fin isolation by backside Si substrate removal etch selective to source and drain epitaxy, are described. For example, an integrated circuit structure includes a plurality of horizontal nanowires above a sub-fin. A gate stack is over the plurality of nanowires and the sub-fin. Epitaxial source or drain structures are on opposite ends of the plurality of horizontal nanowires; and a doped nucleation layer at a base of the epitaxial source or drain structures adjacent to the sub-fin. Where the integrated circuit structure comprises an NMOS transistor, doped nucleation layer comprises a carbon-doped nucleation layer. Where the integrated circuit structure comprises a PMOS transistor, doped nucleation layer comprises a heavy boron-doped nucleation layer.