Methods of forming an air gap adjacent a gate of a transistor and a gate contact above the active region of the transistor

Patent metadata

Field	Value
Publication number	US-10211100-B2
Application number	US-201715469701-A
Country	US
Kind code	B2
Filing date	Mar 27, 2017
Priority date	Mar 27, 2017
Publication date	Feb 19, 2019
Grant date	Feb 19, 2019

Abstract

One method includes performing an etching process to define a gate cavity that exposes an upper surface and at least a portion of the sidewalls of a gate structure and forming a replacement spacer structure adjacent the exposed sidewalls of the gate structure, wherein the replacement spacer structure exposes a portion of the upper surface of the gate structure and includes at least one air space. In this example, the method also includes forming a conformal etch stop layer and a replacement gate cap structure in the gate cavity, selectively removing a portion of the replacement gate cap structure and a portion of the conformal etch stop layer so as to thereby expose the upper surface of the gate structure, and forming a conductive gate contact structure (CB) in the conductive gate contact opening, wherein the entire conductive gate contact structure (CB) is positioned vertically above the active region.

First claim

What is claimed:

1. A method of forming a conductive gate contact structure (CB) for a transistor formed above an active region defined in a semiconducting substrate, said transistor comprising a gate structure with an upper surface and sidewalls and an initial sidewall spacer positioned adjacent said sidewalls of said gate structure, the method comprising:
removing at least a portion of at least said initial sidewall spacer so as thereby define a gate cavity that exposes said upper surface and at least a portion of said sidewalls of said gate structure;
forming a replacement spacer structure in said gate cavity, wherein said replacement spacer structure expose a portion of said upper surface of said gate structure and wherein at least one air space is formed in said replacement spacer structure adjacent at least a portion of at least one sidewall of said gate structure;
forming a replacement gate cap structure in said gate cavity above said replacement spacer structure and on said exposed portion of said upper surface of said gate structure, said replacement gate cap structure comprising a gate cap material positioned above a conformal etch stop layer;
forming a conductive gate contact opening that is positioned vertically above said active region by selectively removing a portion of said replacement gate cap structure so as to thereby expose at least a portion of said upper surface of said gate structure; and
forming said conductive gate contact structure (CB) in said conductive gate contact opening, wherein an entirety of said conductive gate contact structure (CB) is positioned vertically above said active region.

2. The method of claim 1 , wherein:
removing said at least a portion of said at least said initial sidewall spacer comprises removing less than an entirety of said initial sidewall spacer so as to result in a recessed sidewall spacer; and
forming said replacement spacer structure comprises forming said replacement spacer structure above said recessed sidewall spacer and adjacent said exposed sidewalls of said gate structure, wherein said at least one air space is formed in said replacement spacer structure above said recessed sidewall spacer and adjacent at least a portion of at least one sidewall of said gate structure.

3. The method of claim 1 , wherein:
removing said at least a portion of said at least said initial sidewall spacer comprises removing an entirety of said initial sidewall spacer so as to expose a portion of said substrate underlying said initial sidewall spacer; and
forming said replacement spacer structure comprises forming said replacement spacer structure above said exposed portion of said substrate and adjacent said exposed sidewalls of said gate structure, wherein said at least one air space is formed in said replacement spacer structure above said exposed portion of said substrate and adjacent at least a portion of at least one sidewall of said gate structure.

4. The method of claim 1 , wherein forming said replacement spacer structure comprises:
depositing material for said replacement spacer structure in said gate cavity so as to thereby define said air space, wherein said material for said replacement spacer structure covers an entirety of said upper surface of said gate structure; and
performing an anisotropic etching process on said material for said replacement spacer structure so as to remove a portion of said deposited material for said replacement spacer structure from above at least a portion of said upper surface of said gate structure.

5. The method of claim 1 , wherein forming said replacement gate cap structure in said gate cavity comprises:
depositing said gate cap material in said gate cavity and on said conformal etch stop layer, wherein said deposited gate cap material over-fills said gate cavity; and
performing at least one planarization process to remove portions of said deposited gate cap material positioned outside of said gate cavity.

6. The method of claim 1 , wherein forming said conductive gate contact opening comprises:
forming a layer of insulating material having an opening formed therein that exposes a portion of said replacement gate cap structure positioned above said active region, wherein selectively removing said portion of said replacement gate cap structure comprises performing a first selective etching process through said opening in said layer of insulating material to remove a portion of said gate cap material selectively relative to said conformal etch stop layer and performing a second selective etching process through said opening in said layer of insulating material to remove a portion of said conformal etch stop layer so as to thereby expose said at least a portion of said upper surface of said gate structure.

7. The method of claim 1 , wherein said conformal etch stop layer comprises one of HfO 2 , Al 2 O 3 , AlN, said replacement gate cap structure comprises silicon nitride or SiBCN, said replacement spacer structure comprises silicon nitride and said conductive gate contact structure (CB) comprises at least one barrier liner layer.

8. The method of claim 1 , wherein said replacement spacer structure extends around an entire perimeter of said gate structure and is partially positioned above an isolation material that surrounds said active region.

9. The method of claim 1 , further comprising forming a conductive source/drain contact structure (CA) that is conductively coupled to a source/drain region of said transistor, wherein said conductive source/drain contact structure (CA) is axially offset from said conductive gate contact structure (CB) along a gate width direction of said transistor device.

10. The method of claim 1 , wherein said transistor further comprises a conductive source/drain metallization structure conductively coupled to a source/drain region of said transistor and a layer of insulating material formed in a recess above said conductive source/drain metallization structure, wherein removing said at least a portion of said at least said initial sidewall spacer comprises performing at least one etching process to remove said at least said portion of said at least said initial sidewall spacer in the presence of said layer of insulating material formed in said recess, said layer of insulating material covering an upper surface of said conductive source/drain metallization structure during said at least one etching process.

11. A method of forming a conductive gate contact structure (CB) for a transistor formed above an active region defined in a semiconducting substrate, said transistor comprising a gate structure with an upper surface and sidewalls, an initial gate cap structure and an initial sidewall spacer positioned adjacent said sidewalls of said gate structure, the method comprising:
performing at least one etching process to remove said initial gate cap structure and to remove a vertical portion of said initial sidewall spacer so as to result in a recessed sidewall spacer and to thereby define a gate cavity that exposes an upper surface and at least a vertical portion of at least one of said sidewalls of said gate structure;
forming a replacement spacer structure above said recessed sidewall spacer and adjacent said exposed sidewalls of said gate structure, wherein said replacement spacer structure exposes a portion of said upper surface of said gate structure and wherein at least one air space is formed in said replacement spacer structure above said recessed sidewall spacer and adjacent at least a portion of at least one of said sidewalls of said gate structure;
forming a replacement gate cap structure in said gate cavity above said replacement spacer structure and on said exposed por

Assignees

• Globalfoundries Inc

Inventors

• Xie Ruilong
• Liebmann Lars
• Cave Nigel
• Labonte Andre
• Licausi Nicholas
• Bouche Guillaume
• Park Chanro

Classifications

• H10W20/0693

  by forming self-aligned vias · CPC title

• H10W20/077

  on sidewalls or on top surfaces of conductors (H10W20/076 takes precedence) · CPC title

• H10W20/069

  by forming self-aligned vias or self-aligned contact plugs · CPC title

• H10W10/021

  of air gaps · CPC title

• H10W10/20

  Air gaps · CPC title