Electroplating method

Abstract

A substrate with a through-hole is immersed in a plating solution in a plating tank. A pair of anodes are disposed in the plating solution in the plating tank in facing relation to face and reverse sides, respectively, of the substrate in the plating solution. A plurality of plating processes are performed on the face and reverse sides by supplying pulsed currents respectively between the face side of the substrate and one of the anodes which faces the face side of the substrate, and between the reverse side of the substrate and the other anode which faces the reverse side of the substrate. A reverse electrolyzing process is performed on the face and reverse sides between adjacent plating processes by supplying currents in an opposite direction to the pulsed currents respectively between the face side of the substrate and one of the anodes, and between the reverse side of the substrate and the other anode.

1 . An electroplating method comprising:
 immersing a substrate with a through-hole defined therein in a plating solution in a plating tank;   disposing a pair of anodes in the plating solution in the plating tank in facing relation to face and reverse sides, respectively, of the substrate in the plating solution;   performing a plurality of plating processes, each for a predetermined period, on the face and reverse sides of the substrate by supplying pulsed currents respectively between the face side of the substrate and one of the anodes which faces the face side of the substrate, and between the reverse side of the substrate and the other of the anodes which faces the reverse side of the substrate; and   performing a reverse electrolyzing process on the face and reverse sides of the substrate between adjacent ones of the plating processes by supplying currents in an opposite direction to the pulsed currents in the plating processes respectively between the face side of the substrate and one of the anodes which faces the face side of the substrate, and between the reverse side of the substrate and the other of the anodes which faces the reverse side of the substrate.   
     
     
         2 . An electroplating method according to  claim 1 , wherein each of the pulsed currents comprises a PR pulsed current represented by an alternate repetition of a current flowing in a forward direction and a current flowing in a reverse direction. 
     
     
         3 . An electroplating method according to  claim 1 , wherein each of the pulsed currents comprises an on/off pulsed current represented by an alternate repetition of the supply and non-supply of a plating current which flows in a forward direction. 
     
     
         4 . An electroplating method according to  claim 1 , wherein each of the pulsed currents comprises a composite pulsed current represented by a combination of two pulsed currents having different current values. 
     
     
         5 . An electroplating method according to  claim 1 , wherein the plating processes together with the reverse electrolyzing process are performed to gradually increase an average current density as the substrate is progressively plated. 
     
     
         6 . An electroplating method according to  claim 1 , wherein the reverse electrolyzing process is performed a plurality of times before and after a normal electrolyzing cycle in which a pulsed current is supplied in the forward direction.