Process for electrolytic copper plating

Abstract

A process for electrolytic copper plating, that is suitable for the formation of filled vias without compromising the brightness of the deposit is provided. In this process, copper electroplating is carried out in the presence of a transition metal oxide.

What is claimed:  
     
         1 . A process for electrolytic copper plating comprising the steps of contacting a substrate to be plated with an electrolytic copper plating bath comprising a transition metal oxide and subjecting the plating bath to sufficient current density to deposit a layer of copper on the substrate.  
     
     
         2 . The process according to  claim 1  wherein the electrolytic copper plating bath further comprises copper sulfate.  
     
     
         3 . The process of  claim 1  further comprising the step of irradiating the electrolytic copper plating bath with ultraviolet or visible light  
     
     
         4 . The process of  claim 1  wherein the electrolytic copper plating bath further comprises a brightening agent having the structure —X—S—Y, wherein X and Y are independently selected from hydrogen, carbon, sulfur, nitrogen and oxygen, provided that X and Y are the same only when they are carbon.  
     
     
         5 . The process of  claim 1  wherein the substrate is a printed wiring board or a wafer.  
     
     
         6 . The process of  claim 1  wherein the substrate has one or more through-holes or via holes.  
     
     
         7 . A copper plating bath composition suitable for electrolytic copper plating comprising a source of copper ions, an electrolyte, water and a transition metal oxide.  
     
     
         8 . The composition of  claim 8  wherein the transition metal oxide is titanium oxide.  
     
     
         9 . The composition of  claim 8  further comprising a brightening agent having the structure —X—S—Y, wherein X and Y are independently selected from hydrogen, carbon, sulfur, nitrogen and oxygen, provided that X and Y are the same only when they are carbon.