Method for making field effect transistors having sub-lithographic gates

Abstract

A method for the formation of field effect transistors (FETs), and more particularly metal oxide field effect transistors (MOSFETs), comprising the steps of: forming a dielectric stack on a semiconductor structure; defining an etch window on the dielectric stack; defining a gate hole in the dielectric stack by transferring the etch window into the dielectric stack using a reactive ion etching (RIE) process; depositing a side wall layer; removing the side wall layer from horizontal surfaces of the dielectric stack and gate hole such that side wall spacers remain which reduce the lateral size of the gate hole; depositing a gate conductor such that it fills the gate hole; removing the gate conductor covering the portions of the semiconductor structure surrounding the gate hole; removing at least part of the dielectric stack; and removing the side wall spacers.