US 2011/0298017 A1 · REPLACEMENT GATE MOSFET WITH SELF-ALIGNED DIFFUSION CONTACT

Abstract

A replacement gate field effect transistor includes at least one self-aligned contact that overlies a portion of a dielectric gate cap. A replacement gate stack is formed in a cavity formed by removal of a disposable gate stack. The replacement gate stack is subsequently recessed, and a dielectric gate cap having sidewalls that are vertically coincident with outer sidewalls of the gate spacer is formed by filling the recess over the replacement gate stack. An anisotropic etch removes the dielectric material of the planarization layer selective to the material of the dielectric gate cap, thereby forming at least one via cavity having sidewalls that coincide with a portion of the sidewalls of the gate spacer. A portion of each diffusion contact formed by filling the at least one via cavity overlies a portion of the gate spacer and protrudes into the dielectric gate cap.

Claims20

Dependent claims

A semiconductor structure comprising:

a field effect transistor including a gate stack, from bottom to top, of a gate dielectric and a gate conductor, wherein said gate stack is located on a surface of a semiconductor substrate;
a dielectric gate spacer located on a surface of said gate dielectric;
a dielectric gate cap located above said gate stack and contacting upper surfaces of said dielectric gate spacer;
and
a conductive via structure having a sidewall that contacts said dielectric gate spacer and said dielectric gate cap and including an upper conductive via portion that laterally protrudes above said sidewall of said conductive via structure and over a portion of said dielectric gate spacer.

2 more elements

A method of forming a semiconductor structure comprising:

forming a disposable material stack on a surface of said semiconductor substrate;
forming a dielectric gate spacer on sidewalls of said disposable material stack;
forming a dielectric material layer on said surface of said semiconductor substrate, wherein said dielectric gate spacer has inner vertical sidewalls and outer vertical sidewalls, each of which extending from said surface of said semiconductor substrate to a top surface of said dielectric material layer;
forming a gate dielectric and a gate conductor on said semiconductor substrate by replacing said disposable material stack;
forming a recessed space by recessing said gate conductor and said dielectric gate spacer;
forming a dielectric gate cap by filling said recessed space, wherein a topmost surface of said dielectric gate cap is coplanar with a topmost surface of said dielectric material layer after planarization;
and
anisotropically etching a portion of said dielectric material layer and an upper portion of said dielectric gate spacer, wherein a contiguous via cavity exposing a conductive structure underneath said dielectric material layer is formed, and said contiguous via cavity includes a laterally protruding portion that overlies a horizontal surface of said dielectric gate cap that is recessed relative to said topmost surface of said dielectric gate cap.

5 more elements

Dependencies are inferred from the claim text.

Replacement gate mosfet with self-aligned diffusion contact

Life of this patent

Replacement gate mosfet with self-aligned diffusion contact

Life of this patent

Abstract

Claims20