Electroplating method

Abstract

An electroplating method includes: preparing a substrate having via holes formed in a surface; immersing the substrate in a pretreatment solution to carry out pretreatment of the substrate; immersing the substrate in a plating solution without applying a voltage between the substrate and an anode, thereby replacing the pretreatment solution in the via holes with the plating solution; carrying out first-step electroplating of the substrate while controlling the voltage, applied between the substrate and the anode, to be equal to or higher than a voltage which is necessary for an electric current, appropriate to fill a plated metal into the via holes, to flow stably between the substrate and the anode; and carrying outsecond-step electroplating of the substrate while controlling the electric current, flowing between the substrate and the anode, at an electric current appropriate to fill the plated metal into the via holes.

1 . An electroplating method comprising:
 preparing a substrate having via holes formed in a surface;   immersing the substrate in a pretreatment solution to carry out pretreatment of the substrate;   immersing the substrate in a plating solution without applying a voltage between the substrate and an anode disposed opposite the substrate, thereby replacing the pretreatment solution in the via holes with the plating solution;   carrying out first-step electroplating of the substrate while controlling the voltage, applied between the substrate and the anode, to be equal to or higher than a voltage which is necessary for an electric current, appropriate to fill a plated metal into the via holes, to flow stably between the substrate and the anode; and then   carrying out second-step electroplating of the substrate while controlling the electric current, flowing between the substrate and the anode, at an electric current appropriate to fill the plated metal into the via holes.   
     
     
         2 . The electroplating method according to  claim 1 , wherein the substrate is immersed in the plating solution for 10 to 60 seconds without applying a voltage between the substrate and the anode. 
     
     
         3 . The electroplating method according to  claim 1 , wherein the first-step electroplating is carried out for one second to ten minutes. 
     
     
         4 . The electroplating method according to  claim 1 , wherein the second-step electroplating is carried out in such a manner that the electric current, flowing between the substrate and the anode, is changed in a stepwise fashion. 
     
     
         5 . The electroplating method according to  claim 1 , wherein the plated metal is copper, and a metal other than copper is exposed on at least part of surfaces of the via holes. 
     
     
         6 . The electroplating method according to  claim 5 , wherein the metal other than copper is ruthenium or cobalt, or an alloy thereof.