Protruding spacers for self-aligned contacts

Abstract

A protruding spacer that protrudes above the top surface of a gate electrode structure provides enhanced resistance to exposure of the gate electrode during the etch process used to form self-aligned contacts. The protruding spacer may be formed using an amorphous carbon sacrificial layer as the top layer of the patterned gate electrode structure. Dielectric spacers are formed alongside the gate electrode structure, including alongside the sacrificial amorphous carbon layer. The dielectric spacers extend substantially to the top of the amorphous carbon layer. The amorphous carbon layer is then removed such that the remaining gate structure includes dielectric spacers that have a protruding section that protrudes above the top surface of the remaining gate structure. A nitride layer may be formed over the gate structure. Such a structure prevents exposure of the gate electrode during the formation of self-aligned contacts, and shorting, once the contact openings are filled.