Field effect transistor gate process and structure

Abstract

A Schottky gate (27′, 27″) of a metal-semiconductor FET (20′, 20″) is formed on a semiconductor comprising substrate (21) by, etching a gate recess (36) so as to expose a slightly depressed surface (362) of the substrate (21), the etching step also producing surface undercut cavities (363) extending laterally under the etch mask (43) from the gate recess (36), then conformally coating the slightly depressed surface (362) with a first Schottky forming conductor (40′) and substantially also coating inner surfaces (366) of the surface undercut cavities (363), and forming a Schottky contact to the semiconductor comprising substrate (21), adapted when biased to control current flow in a channel (22) extending between source (23) and drain (24) of the FET (20′, 20″) under the gate recess (36). In further embodiments, a conformal or non-conformal barrier layer conductor (41′, 41″) may be provided over the Schottky forming conductor (40′) and a thicker overlying gate conductor (442, 272) provided over the barrier layer conductor (41′, 41″).

Dependencies are inferred from the claim text.