Self-forming, self-aligned barriers for back-end interconnects and methods of making same

Abstract

Processes of forming an insulated wire into an interlayer dielectric layer (ILD) of a back-end metallization includes thermally treating a metallic barrier precursor under conditions to cause at least one alloying element in the barrier precursor to form a dielectric barrier between the wire and the ILD. The dielectric barrier is therefore a self-forming, self-aligned barrier. Thermal processing is done under conditions to cause the at least one alloying element to migrate from a zone of higher concentration thereof to a zone of lower concentration thereof to further form the dielectric barrier. Various apparatus are made by the process.

What is claimed is: 
     
         1 . A process of forming a back-end metallization, comprising:
 forming a wire into a interlayer dielectric layer (ILD) recess and upon a barrier precursor material, wherein the wire and the barrier precursor material have at least one metal in common, and wherein the at least one metal in common in the barrier precursor includes at least one further alloying element; and   thermally treating the barrier precursor under conditions to cause at least one alloying element in the barrier precursor to form a dielectric barrier between the wire and the ILD and further under conditions to cause the at least one alloying element to migrate from a zone of higher concentration thereof to a zone of lower concentration thereof to further form the dielectric barrier.   
     
     
         2 . The process of  claim 1 , wherein the dielectric barrier is a silicide barrier that is formed. 
     
     
         3 . The process of  claim 1 , wherein the wire has a top surface that is coplanar with a top surface of the ILD, and before thermally treating, the process further including:
 forming a composite dielectric layer upon the top surface, wherein the composite dielectric layer includes:
 a first film that is substantially the same chemistry as the ILD, and wherein the ILD has dielectric constant that is equal to or lower than that of silica; 
 a second film above the first film that is denser than the first film by a factor in a range from 1.01 to 2; and 
 a subsequent film above the second film. 
   
     
     
         4 . The process of  claim 1 , wherein thermally treating causes the barrier precursor to form an integral, continuous, and closed dielectric structure that is self-formed and self-aligned around the wire. 
     
     
         5 . The process of  claim 1 , before forming the wire, the process includes forming the barrier precursor as a slug in the recess. 
     
     
         6 . The process of  claim 1 , wherein the wire has a top surface, wherein the wire is first set in a barrier liner that contacts a bottom surface that opposite the top surface and two side surfaces, and wherein thermally treating the barrier precursor causes the at least one alloying element to migrate and form the dielectric barrier as a top barrier on the top surface and only adjacent the wire. 
     
     
         7 . The process of  claim 1 , wherein the wire has a top surface, wherein the wire is first set in a barrier liner that contacts a bottom surface that opposite the top surface and two side surfaces, and wherein thermally treating the barrier precursor causes the at least one alloying element to migrate and form the dielectric barrier as a top barrier on the top surface and only adjacent the wire, and wherein the barrier liner is selected from the group consisting of a refractory metal, tantalum, a tantalum alloy, titanium, a titanium alloy, vanadium, a vanadium alloy, ruthenium, a ruthenium alloy, osmium, an osmium alloy, cobalt, a cobalt alloy, rhodium, an rhodium alloy, iridium, and an iridium alloy. 
     
     
         8 . The process of  claim 1 , further including:
 opening a via in the composite dielectric;   forming a liner film in the via and upon the composite dielectric; and   forming a subsequent wire that is coupled to the wire through the via.   
     
     
         9 . The process  claim 1 , further including;
 forming a subsequent dielectric layer above the subsequent wire;   opening a via the subsequent dielectric layer;   forming a liner film in the via and upon the composite dielectric; and   forming a next subsequent wire that is coupled to the subsequent wire through the subsequent via.   
     
     
         10 . The process of  claim 1 , wherein the wire has a top surface, wherein the wire is first set in a barrier liner that contacts a bottom surface that opposite the top surface and two side surfaces, the process further including before forming the wire:
 forming the barrier precursor as a slug in the recess and in contact with the barrier liner.