Barrier-Less Structures

Abstract

Interconnect structures and method of forming the same are disclosed herein. An exemplary interconnect structure includes a first contact feature in a first dielectric layer, a second dielectric layer over the first dielectric layer, a second contact feature over the first contact feature, a barrier layer between the second dielectric layer and the second contact feature, and a liner between the barrier layer and the second contact feature. An interface between the first contact feature and the second contact feature includes the liner but is free of the barrier layer.

1 - 7 . (canceled) 
     
     
         8 . An interconnect structure comprising:
 a first contact feature in a first dielectric layer;   a second contact feature in a second dielectric layer over the first dielectric layer, the second contact feature comprising:
 a contact via portion comprising:
 a reset layer directly on the first contact feature, and 
 a first metal fill layer over the reset layer; 
 
 a conductive line portion comprising:
 a first barrier layer over the first metal fill layer, 
 a liner over the first barrier layer, and 
 a second metal fill layer over the liner; and 
 
   a second barrier layer between the second contact feature and the second dielectric layer.   
     
     
         9 . The interconnect structure of  claim 8 , wherein the first barrier layer comprises tantalum, tantalum nitride, tantalum carbide, titanium, titanium nitride, titanium carbide, or combinations thereof. 
     
     
         10 . The interconnect structure of  claim 8 , wherein the second barrier layer comprises tantalum, tantalum nitride, tantalum carbide, titanium, titanium nitride, titanium carbide, or combinations thereof. 
     
     
         11 . The interconnect structure of  claim 8 , wherein the liner comprises cobalt, cobalt nitride, ruthenium nitride, or combinations thereof. 
     
     
         12 . The interconnect structure of  claim 8 , wherein the reset layer comprises cobalt or ruthenium. 
     
     
         13 . The interconnect structure of  claim 8 ,
 wherein the first contact feature comprises a first conductive material,   wherein the reset layer comprises a second conductive material different from the first conductive material.   
     
     
         14 . The interconnect structure of  claim 8 ,
 wherein the first contact feature and the second metal fill layer are formed of the same conductive material.   
     
     
         15 . The interconnect structure of  claim 8 ,
 wherein a top surface of the conductive line portion is planar,   wherein a top surface of the contact via portion is convex in shape.   
     
     
         16 - 20 . (canceled) 
     
     
         21 . An interconnect structure comprising:
 a first contact feature in a first dielectric layer;   a second dielectric layer over the first dielectric layer; and   a second contact feature in the second dielectric layer, the second contact feature comprising:
 a first metal fill layer over the first contact feature; 
 a second metal fill layer over the first metal fill layer; 
 a first barrier layer disposed between the first metal fill layer and the second metal fill layer; and 
 a first liner disposed between the first metal fill layer and the first barrier layer. 
   
     
     
         22 . The interconnect structure of  claim 21 , wherein a composition of the first barrier layer is different from a composition of the first liner. 
     
     
         23 . The interconnect structure of  claim 21 , wherein the first barrier layer comprises tantalum, tantalum nitride, tantalum carbide, titanium, titanium nitride, titanium carbide, or combinations thereof. 
     
     
         24 . The interconnect structure of  claim 21 , wherein the first liner comprises cobalt, cobalt nitride, ruthenium nitride, or combinations thereof. 
     
     
         25 . The interconnect structure of  claim 21 , wherein the first contact feature comprises:
 a third metal fill layer; and   a second liner between the third metal fill layer and the first dielectric layer,   wherein the first contact feature is spaced apart from the first dielectric layer by a second barrier layer.   
     
     
         26 . The interconnect structure of  claim 25 ,
 wherein the third metal fill layer comprises nickel, tantalum, titanium, aluminum, copper, cobalt, ruthenium, and tungsten,   wherein the second liner comprises cobalt, cobalt nitride, ruthenium nitride, or combinations thereof, and   wherein the second barrier layer comprises tantalum, tantalum nitride, tantalum carbide, titanium, titanium nitride, titanium carbide, or combinations thereof.   
     
     
         27 . The interconnect structure of  claim 26 , further comprising a reset layer sandwiched between the first metal fill layer and the first contact feature. 
     
     
         28 . The interconnect structure of  claim 27 , wherein the reset layer comprises cobalt or ruthenium. 
     
     
         29 . An interconnect structure comprising:
 a first dielectric layer;   a second dielectric layer over the first dielectric layer   a first contact feature in the first dielectric layer;   a second contact feature in the second dielectric layer, the second contact feature comprising:
 a first metal fill layer over the first contact feature, 
 a first barrier layer disposed over the first metal fill layer, 
 a liner disposed over the first barrier layer, and 
 a second metal fill layer over the liner; and 
   a second barrier layer disposed between the second contact feature and the second dielectric layer.   
     
     
         30 . The interconnect structure of  claim 29 , wherein the second metal fill layer is spaced apart from the second dielectric layer by the liner, the first barrier layer, and the second barrier layer. 
     
     
         31 . The interconnect structure of  claim 29 ,
 wherein the first metal fill layer and the second metal fill layer comprise nickel, tantalum, titanium, aluminum, copper, cobalt, ruthenium, and tungsten,   wherein the liner comprises cobalt, cobalt nitride, ruthenium nitride, or combinations thereof, and   wherein the first barrier layer and the second barrier layer comprise tantalum, tantalum nitride, tantalum carbide, titanium, titanium nitride, titanium carbide, or combinations thereof.   
     
     
         32 . The interconnect structure of  claim 29 ,
 wherein a top surface of the second metal fill layer is planar,   wherein a top surface of the first metal fill layer is convex in shape.