US 7,682,917 B2 · Disposable metallic or semiconductor gate spacer

Abstract

A disposable spacer is formed directly on or in close proximity to the sidewalls of a gate electrode and a gate dielectric. The disposable spacer comprises a material that scavenges oxygen such as a metal, a metal nitride, or a semiconductor material having high reactivity with oxygen. The disposable gate spacer absorbs any oxygen during subsequent high temperature processing such as a stress memorization anneal. A metal is deposited over, and reacted with, the gate electrode and source and drain regions to form metal semiconductor alloy regions. The disposable gate spacer is subsequently removed selective to the metal semiconductor alloy regions. A porous or non-porous low-k dielectric material is deposited to provide a low parasitic capacitance between the gate electrode and the source and drain regions. The gate dielectric maintains the original dielectric constant since the disposable gate spacer prevents absorption of additional oxygen during high temperature processes.

Claims20

Dependent claims

A method of forming a semiconductor structure comprising:

forming a stack of a gate dielectric and a gate electrode on a semiconductor substrate;
forming a disposable gate spacer comprising a metal, a metal nitride, or a germanium containing alloy directly on sidewalls of said gate dielectric and said gate electrode;
forming a stressed silicon nitride layer having an intrinsically compressive stress or an intrinsically tensile stress on said disposable gate spacer;
transferring stress from said stressed silicon nitride layer into a portion of said semiconductor substrate by performing an anneal while said disposable gate spacer is present on said semiconductor substrate;
removing said stressed silicon nitride layer;
forming source and drain metal semiconductor alloy regions that are offset from said sidewalls by said disposable gate spacer on said semiconductor substrate;
and
removing said disposable gate spacer selective to said source and drain metal semiconductor alloy regions and said gate electrode.

5 more elements

Dependencies are inferred from the claim text.

Disposable metallic or semiconductor gate spacer

Life of this patent

Disposable metallic or semiconductor gate spacer

Life of this patent

Abstract

Claims20