Method of direct plating of copper on a ruthenium alloy

Abstract

A method is disclosed for depositing a copper seed layer onto a substrate surface. In one embodiment, the method includes providing a substrate having a barrier layer disposed on a substrate surface, wherein the barrier layer has a barrier surface comprising a material selected from the group consisting of cobalt, ruthenium, tungsten, titanium, and a compound of two or more thereof, and exposing the substrate to a non-complexed, acid electrochemical plating solution with a plating bias applied across the substrate surface to deposit a copper-containing seed layer directly on the barrier surface without intervening layer disposed therebetween.

1 . A method for depositing a copper-containing seed layer onto a barrier layer, comprising:
 providing a substrate having a barrier layer disposed on a substrate surface, wherein the barrier layer has a barrier surface comprising a material selected from the group consisting of cobalt, ruthenium, tungsten, titanium, and a compound of two or more thereof; and   exposing the substrate to a non-complexed, acid electrochemical plating solution with a plating bias applied across the substrate surface to deposit a copper-containing seed layer directly on the barrier surface without intervening layer disposed therebetween.   
     
     
         2 . The method of  claim 1 , wherein the electrochemical plating solution comprises a copper source compounds at a concentration in the range from about 0.02 M to about 0.8 M. 
     
     
         3 . The method of  claim 2 , wherein the electrochemical plating solution has a pH value of between about 3 and about 7. 
     
     
         4 . The method of  claim 1 , wherein the electrochemical plating solution comprises organic additive agents. 
     
     
         5 . The method of  claim 1 , wherein the plating bias has a more negative potential than required to oxidize the barrier layer. 
     
     
         6 . The method of  claim 5 , wherein the plating bias has a current density between about 0.5 mA/cm 2  and about 5 mA/cm 2 . 
     
     
         7 . The method of  claim 1 , wherein the copper-containing seed layer has a thickness of less than about 200 Å. 
     
     
         8 . The method of  claim 1 , further comprising:
 thermally annealing the barrier layer before exposing the substrate to the non-complexed, electrochemical plating solution.   
     
     
         9 . A method for electrochemical plating a metal layer on a substrate, comprising:
 providing a substrate having one or more interconnect features formed therein;   conformally depositing a barrier layer onto the substrate and exposed surfaces of the one or more interconnect features, wherein the barrier layer has a barrier surface comprising a material selected from the group consisting of cobalt, ruthenium, tungsten, titanium, and compound thereof;   exposing the substrate to a non-complexed, electrochemical plating solution having a pH valve of between about 3 and about 7 with a plating bias applied across the substrate surface to deposit a copper-containing seed layer directly on the barrier surface without intervening layer disposed therebetween; and   applying an electrical bias across the substrate surface to fill the one or more interconnect features with copper in the non-complexed, electrochemical plating solution having the pH valve of between about 3 and about 7.   
     
     
         10 . The method of  claim 9 , wherein the electrochemical plating solution comprises a copper source compounds at a concentration in the range from about 0.02 M to about 0.8 M. 
     
     
         11 . The method of  claim 9 , wherein the electrochemical plating solution has a pH value of between 4.5 and about 6.5. 
     
     
         12 . The method of  claim 9 , wherein the plating bias has a more negative potential than required to oxidize the barrier layer. 
     
     
         13 . The method of  claim 12 , wherein the plating bias has a current density between about 0.5 mA/cm 2  and about 5 mA/cm 2 . 
     
     
         14 . The method of  claim 9 , further comprising:
 thermally annealing the barrier layer before exposing the substrate to the non-complexed, electrochemical plating solution.   
     
     
         15 . The method of  claim 9 , further comprising:
 thermally annealing the copper in an oxygen free environment.