Contact resistance reduction for advanced technology nodes

Abstract

A source/drain contact includes a first portion arranged on a substrate and extending between a first gate and a second gate; a second portion arranged on the first portion and extending over the first gate and the second gate, the second portion including a partially recessed liner and a metal disposed on the partially recessed liner, and the partially recessed liner arranged on an endwall of the second portion and in contact with the first portion; and an oxide disposed around the second portion and on the first gate and the second gate.

What is claimed is: 
     
         1 . A method of making a source/drain contact, the method comprising:
 forming a first trench in an inter-layer dielectric (ILD) arranged on a substrate, the first trench extending between a first gate and a second gate;   filling the first trench with a metal to form a first portion of the source/drain contact;   depositing an oxide on the first portion of the source/drain contact, the first gate, and the second gate;   forming a second trench in the oxide to form a second portion of the source/drain contact;   depositing a liner on an endwall of the second trench and on a sidewall of the second trench, the liner contacting the first portion of the source/drain contact;   depositing a metal on the liner to fill the trench;   recessing the liner by a partial etch process such that a portion of the liner remains arranged on the endwall of the trench between the metal and the first portion, the partial etch process forming a recess between the oxide and the metal; and   depositing an oxide liner in the recess to form an oxide spacer between the oxide and the liner.   
     
     
         2 . The method of  claim 1 , wherein the liner is titanium nitride, and the metal is tungsten. 
     
     
         3 . The method of  claim 1 , wherein the liner is recessed by a wet etch process or a dry etch process. 
     
     
         4 . The method of  claim 1 , wherein the oxide spacer has a thickness in a range from about 5 to about 50 nm. 
     
     
         5 . The method of  claim 1 , wherein the oxide liner is silicon dioxide, tetraethylorthosilicate oxide, high aspect ratio plasma oxide, high temperature oxide, high density plasma (HDP) oxide, or a combination thereof. 
     
     
         6 . The method of  claim 1 , wherein the oxide liner comprises a different material than the oxide disposed on the first gate and the second gate. 
     
     
         7 . A method of making a source/drain contact, the method comprising:
 forming a first trench in an inter-layer dielectric (ILD) arranged on a substrate, the first trench extending between a first gate and a second gate;   filling the first trench with a metal to form a first portion of the source/drain contact;   depositing a first oxide on the first portion of the source/drain contact, the first gate, and the second gate;   forming a second trench in the first oxide to form a second portion of the source/drain contact;   depositing a liner on an endwall of the second trench and on a sidewall of the second trench, the liner contacting the first portion of the source/drain contact;   depositing a metal on the liner to fill the second trench;   recessing the liner by a partial etch process such that a portion of the liner remains arranged on the endwall of the trench between the metal and the first portion, the partial etch process forming a recess between the first oxide and the metal;   recessing the first oxide by a partial etch process such that a portion of the first oxide remains arranged on the first gate and the second gate; and   depositing a second oxide on the first oxide to form a bilayer oxide over the first gate and the second gate.   
     
     
         8 . The method of  claim 7 , further comprising depositing a metal layer on the metal filling the second trench after recessing the liner and the first oxide, and then etching to form a metal spacer along a sidewall of the metal filling the second trench. 
     
     
         9 . The method of  claim 8 , wherein the metal spacer is arranged between the metal and the second oxide. 
     
     
         10 . The method of  claim 8 , wherein the metal layer is cobalt or copper. 
     
     
         11 . The method of  claim 7 , wherein the first oxide and the second oxide comprise a different material. 
     
     
         12 . The method of  claim 7 , wherein recessing the first oxide and the liner expose the metal, and the second oxide contacts the metal. 
     
     
         13 . The method of  claim 7 , wherein the second oxide is a low-k oxide with a k<4.0. 
     
     
         14 . A source/drain contact, comprising:
 a first portion arranged on a substrate and extending between a first gate and a second gate;   a second portion arranged on the first portion and extending over the first gate and the second gate, the second portion comprising a partially recessed liner and a metal disposed on the partially recessed liner, and the partially recessed liner arranged on an endwall of the second portion and in contact with the first portion; and   an oxide disposed around the second portion and on the first gate and the second gate.   
     
     
         15 . The source/drain contact of  claim 14 , wherein the partially recessed liner comprises titanium nitride. 
     
     
         16 . The source/drain contact of  claim 14 , further comprising a metal spacer arranged along a sidewall of the second portion and over the recessed liner. 
     
     
         17 . The source/drain contact of  claim 14 , wherein the oxide is a bilayer oxide comprising two oxide material layers, a first oxide material layer disposed adjacent to the partially recessed liner, and a second oxide material layer disposed on the first oxide material layer and adjacent to the metal. 
     
     
         18 . The source/drain contact of  claim 17 , wherein the second oxide material layer contacts the metal. 
     
     
         19 . The source/drain contact of  claim 17 , wherein the second oxide material layer is a low-k oxide. 
     
     
         20 . The source/drain contact of  claim 15 , further comprising an oxide liner disposed on a sidewall of the metal and on the partially recessed liner, the oxide liner arranged between the oxide and the metal.