Patent ID: 10608083

Abstract:
Methods are provided to construct field-effect transistors comprising low-resistance metallic gate structures. A field-effect transistor includes a nanosheet stack and a metal gate which covers a gate region of the nanosheet stack. The nanosheet stack includes nanosheet channel layers and an etch stop layer disposed above an upper nanosheet channel layer. The metal gate includes a work function metal which encapsulates the nanosheet channel layers, and a gate electrode disposed above and in contact with the work function metal. An upper surface of the work function metal is recessed to be substantially coplanar with the etch stop layer. The gate electrode has a resistivity which is less than a resistivity of the work function metal. The etch stop layer protects the portion of the work function metal disposed between the etch stop layer and the upper nanosheet channel layer from being etched when recessing the work function metal.