Selective cobalt deposition on copper surfaces

Abstract

Embodiments of the invention provide processes to selectively form a cobalt layer on a copper surface over exposed dielectric surfaces. In one embodiment, a method for capping a copper surface on a substrate is provided which includes positioning a substrate within a processing chamber, wherein the substrate contains a contaminated copper surface and a dielectric surface, exposing the contaminated copper surface to a reducing agent while forming a copper surface during a pre-treatment process, exposing the substrate to a cobalt precursor gas to selectively form a cobalt capping layer over the copper surface while leaving exposed the dielectric surface during a vapor deposition process, and depositing a dielectric barrier layer over the cobalt capping layer and the dielectric surface. In another embodiment, a deposition-treatment cycle includes performing the vapor deposition process and subsequently a post-treatment process, which deposition-treatment cycle may be repeated to form multiple cobalt capping layers.

1 - 20 . (canceled) 
     
     
         21 . A method for capping a copper surface on a substrate, comprising:
 positioning a substrate within a processing chamber, wherein the substrate comprises a copper oxide surface and a dielectric surface;   exposing the copper oxide surface to a reducing agent while forming a metallic copper surface during a thermal pre-treatment process, wherein the reducing agent comprises hydrogen gas and the substrate is heated to a temperature within a range from about 200° C. to about 400° C. during the thermal pre-treatment process;   exposing the substrate to a cobalt precursor gas to selectively form a cobalt capping layer over the metallic copper surface while leaving exposed the dielectric surface during a vapor deposition process;   exposing the cobalt capping layer to a reagent and a plasma during a post-treatment process; and   depositing a dielectric barrier layer over the cobalt capping layer and the dielectric surface.   
     
     
         22 . The method of  claim 21 , further comprising chemically reducing copper oxides on the copper oxide surface to form the metallic copper surface during the thermal pre-treatment process. 
     
     
         23 . The method of  claim 21 , wherein the reagent is selected from the group consisting of: nitrogen (N 2 ), ammonia (NH 3 ), hydrogen (H 2 ), ammonia/nitrogen mixture, and combinations thereof. 
     
     
         24 . The method of  claim 23 , wherein a deposition-treatment cycle comprises performing the vapor deposition process and subsequently the post-treatment process. 
     
     
         25 . The method of  claim 24 , wherein the deposition-treatment cycle is performed 2, 3, or more times to deposit multiple cobalt capping layers. 
     
     
         26 . The method of  claim 25 , wherein each of the cobalt capping layers is deposited to a thickness within a range from about 3 Å to about 5 Å during each of the deposition-treatment cycles. 
     
     
         27 . The method of  claim 21 , wherein the cobalt capping layer has a thickness within a range from about 4 Å to about 20 Å. 
     
     
         28 . The method of  claim 21 , wherein the cobalt capping layer has a thickness of less than about 10 Å. 
     
     
         29 . The method of  claim 28 , wherein the substrate is exposed to a deposition gas comprising the cobalt precursor gas and hydrogen gas during the vapor deposition process, the vapor deposition process is a thermal chemical vapor deposition process. 
     
     
         30 . The method of  claim 28 , wherein the substrate is exposed to a deposition gas comprising the cobalt precursor gas and hydrogen gas during the vapor deposition process, the vapor deposition process is an atomic layer deposition process. 
     
     
         31 . The method of  claim 21 , wherein the cobalt precursor gas comprises a cobalt precursor which has the general chemical formula (CO) x Co y L z , wherein:
 X is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12;   Y is 1, 2, 3, 4, or 5;   Z is 1, 2, 3, 4, 5, 6, 7, or 8; and   L is a ligand independently selected from the group consisting of: cyclopentadienyl, alkylcyclopentadienyl, methylcyclopentadienyl, pentamethylcyclo-pentadienyl, pentadienyl, alkylpentadienyl, cyclobutadienyl, butadienyl, and combinations thereof.   
     
     
         32 . The method of  claim 21 , wherein the cobalt precursor gas comprises a cobalt precursor selected from the group consisting of: cyclopentadienyl cobalt bis(carbonyl), methylcyclopentadienyl cobalt bis(carbonyl), ethylcyclopentadienyl cobalt bis(carbonyl), pentamethylcyclopentadienyl cobalt bis(carbonyl), bis(cyclo-pentadienyl) cobalt, (cyclopentadienyl) cobalt (cyclohexadienyl), cyclopentadienyl cobalt (1,3-hexadienyl), (cyclobutadienyl) cobalt (cyclopentadienyl), bis(methyl-cyclopentadienyl) cobalt, (cyclopentadienyl) cobalt (5-methylcyclopentadienyl), bis(ethylene) cobalt (pentamethylcyclopentadienyl), derivatives thereof, complexes thereof, plasmas thereof, and combinations thereof. 
     
     
         33 . The method of  claim 32 , wherein the cobalt precursor comprises cyclopentadienyl cobalt bis(carbonyl).