Surface treatment to improve cctba based cvd co nucleation on dielectric substrate

Abstract

Embodiments of the present invention generally relate to a method of forming a cobalt layer on a dielectric material without incubation delay. Prior to depositing the cobalt layer using CVD, the surface of the dielectric material is pretreated at a temperature between 100° C. and 250° C. Since the subsequent CVD cobalt process is also performed at between 100° C. and 250° C., one processing chamber is used for pretreating the dielectric material and forming of the cobalt layer. The combination of processing steps enables use of two processing chambers to deposit cobalt.

1 . A method for forming a metal interconnect, comprising:
 placing a substrate into a processing chamber;   pretreating a surface of the substrate at a temperature between 100° C. and 250° C., wherein the pretreating the surface of the substrate comprises exposing the surface to an ammonia or nitrogen plasma; and   depositing a cobalt layer on the pretreated surface.   
     
     
         2 . The method of  claim 1 , wherein the monolayer of molecules further comprises nitrogen. 
     
     
         3 . The method of  claim 1 , wherein the pretreating the surface of the substrate further comprises exposing the surface to a titanium containing precursor gas prior to exposing the surface to the ammonia or nitrogen plasma. 
     
     
         4 . The method of  claim 3 , wherein the titanium containing precursor gas comprises tetrakis(dimethylamino)titanium or titanium tetrachloride. 
     
     
         5 . The method of  claim 1 , wherein the pretreating the surface of the substrate further comprises exposing the surface to a titanium containing precursor gas after exposing the surface to the ammonia or nitrogen plasma. 
     
     
         6 . The method of  claim 5 , wherein the titanium containing precursor gas comprises tetrakis(dimethylamino)titanium or titanium tetrachloride. 
     
     
         7 . The method of  claim 1 , wherein the cobalt layer is deposited by a chemical vapor deposition process. 
     
     
         8 . The method of  claim 7 , wherein an organometallic precursor gas is used in the chemical vapor deposition process. 
     
     
         9 . The method of  claim 8 , wherein the organometallic precursor gas comprises dicobalt hexacarbonyl tertbutyl acetylene. 
     
     
         10 . The method of  claim 9 , wherein the chemical vapor deposition is performed at a temperature between 100° C. and 250° C. 
     
     
         11 . The method of  claim 10 , wherein the surface of the substrate comprises silicon dioxide or a low-k dielectric.