Electrolytic processing apparatus and electrolytic processing method

Abstract

An electrolytic processing apparatus, prior to carrying out plating directly on, e.g., a ruthenium film of a substrate using the ruthenium film as a seed layer, can securely remove a passive layer formed on a surface of the ruthenium film even when the substrate is a large-sized high-resistance substrate, such as a 300-mm wafer, thereby reducing the terminal effect during the subsequent plating, improving the quality of a plated film and enabling filling of a void-free plated film into a fine interconnect pattern. The electrolytic processing apparatus includes: an anode disposed opposite a seed layer of a noble metal or a high-melting metal, formed on a substrate; a porous body impregnated with an electrolytic solution, disposed in a space, filled with the electrolytic solution, between the substrate and the anode; and a control section for controlling an electric field on a surface of the seed layer so that a reduction reaction takes place in the seed layer, thereby electrolytically and electrochemically removing a passive layer formed in the surface of the seed layer.

1 . An electrolytic processing apparatus comprising:
 an anode disposed opposite a seed layer of a noble metal or a high-melting metal, formed on a substrate;   a porous body impregnated with an electrolytic solution, disposed in a space, filled with the electrolytic solution, between the substrate and the anode; and   a control section for controlling an electric field on a surface of the seed layer so that a reduction reaction takes place in the seed layer, thereby electrolytically and electrochemically removing a passive layer formed on the surface of the seed layer.   
     
     
         2 . The electrolytic processing apparatus according to  claim 1 , wherein a shield plate for limiting the area of electrolytic processing is disposed between the porous body and the anode. 
     
     
         3 . The electrolytic processing apparatus according to  claim 1 , wherein the anode is comprised of a disk-shaped anode, or one or more ring-shaped anodes, or a combination thereof. 
     
     
         4 . The electrolytic processing apparatus according to  claim 1  further comprising a gas removal mechanism for removing a gas generated from the surface of the seed layer during the electrolytic processing. 
     
     
         5 . The electrolytic processing apparatus according to  claim 1 , wherein the seed layer is comprised of a ruthenium film or a ruthenium alloy film having a thickness of not more than 10 nm. 
     
     
         6 . An electrolytic processing method comprising:
 disposing a porous body between a substrate having a seed layer of a noble metal or a high-melting metal and an anode disposed opposite the seed layer;   filling an electrolytic solution into a space between the substrate and the anode while impregnating the porous body with the electrolytic solution; and   electrolytically and electrochemically removing a passive layer formed on a surface of the seed layer while controlling an electric field on the surface of the seed layer so that a reduction reaction takes place in the seed layer.   
     
     
         7 . The electrolytic processing method according to  claim 6 , wherein the voltage or electric current applied between the seed layer and the anode is gradually increased in accordance with the electrolytic processing area of the substrate. 
     
     
         8 . The electrolytic processing method according to  claim 6 , wherein a shield plate is disposed between the anode and the porous body to limit the area of electrolytic processing. 
     
     
         9 . The electrolytic processing method according to  claim 6 , wherein the seed layer is comprised of a ruthenium film or a ruthenium alloy film having a thickness of not more than 10 nm. 
     
     
         10 . An electrolytic processing method comprising:
 filling an electrolytic solution containing sulfuric acid as an electrolyte into a space between a substrate, having a seed layer of a noble metal or a high-melting metal, and an anode disposed opposite the seed layer; and   applying an electric current between the seed layer and the anode in such a manner as to satisfy the following formula (1), thereby electrolytically and electrochemically removing a passive layer formed on a surface of the seed layer:
     A≧ 1.15× B+ 5  (1) 
   wherein “A” represents the sulfuric acid concentration of the electrolytic solution (g/L), and “B” represents current density (mA/cm 2 ).   
     
     
         11 . The electrolytic processing method according to  claim 10 , wherein the seed layer is comprised of a ruthenium film or a ruthenium alloy film having a thickness of not more than 10 nm.