Core-shell-shell nanowire transistor and fabrication method

A fabrication method is provided for a core-shell-shell (CSS) nanowire transistor (NWT). The method provides a cylindrical CSS nanostructure with a semiconductor core, an insulator shell, and a conductive shell. The CSS nanostructure has a lower hemicylinder overlying a substrate surface. A first insulating film is conformally deposited overlying the CSS nanostructure and anisotropically plasma etched. Insulating reentrant stringers are formed adjacent the nanostructure lower hemicylinder. A conductive film is conformally deposited and selected regions are anisotropically plasma etched, forming conductive film gate straps overlying a gate electrode in a center section of the CSS nanostructure. An isotropically etching removes the insulating reentrant stringers adjacent the center section of the CSS nanostructure, and an isotropically etching of the conductive shell overlying the S/D regions is performed. A screen oxide layer is deposited over the CSS nanostructure. The source/drain (S/D) regions in end sections of the CS nanostructure flanking are doped.