Method for filling blind via holes

Abstract

A copper sulfate plating bath is used which contains (a) a polyether containing at least five ether oxygen atoms in molecule, and (b) a compound represented by formula of R 1 —S—(CH 2 O) n —R 2 —SO 3 M (wherein, R 1 is a hydrogen atom, —(S) n —(CH 2 O) n —R 2 —SO 3 M, or —CS n —(CH 2 O) n —R 2 —SO 3 M, R 2 is an alkylene group having 3 to 8 carbon atoms, M is a hydrogen atom or alkaline metal, and n is 0 or 1). A copper-plating is carried out by reversing the current in a cycle of 1 to 50 msec. for a time of positive electrolysis, 0.2 to 5 msec. for a time of reverse electrolysis, and 1 to 50 msec. for a stop time, between one electrode comprising the seed layer and the other electrode immersed in said copper sulfate plating bath.

1 . A method for filling blind via holes, with metallic copper, comprises etching a substrate to form blind via holes with an inner wall, forming a seed layer for plating on the inner wall of the blind via holes, and conducting an electric copper-plating treatment with the seed layer as one electrode, in a copper sulfate plating bath, to fill the bind via holes with metallic copper, wherein said copper sulfate plating bath contains ingredients (a) and (b) below: 
 (a) a polyether containing at least five ether oxygen atoms in a molecule; and    (b) a compound represented by formula (I) below:   R 1 —S—(CH 2 O) n —R 2 —SO 3 M  (I)   wherein, R 1  is a hydrogen atom, —(S) n (CH 2 O) n —R 2 —SO 3 M, or —CS n —(CH 2 O) n —R 2 —SO 3 M, R 2  is an alkylene group having 3 to 8 carbon atoms, m is a hydrogen atom or alkaline metal, and n is 0 or 1,    and said electric copper-plating treatment is conducted with reversing the current in a cycle of 1 to 50 msec. for a time of positive electrolysis, 0.2 to 5 msec. for a time of reverse electrolysis, and 1 to 50 msec. for a stop time, between one electrode comprising the seed layer and another electrode immersed in said copper sulfate plating bath.    
     
     
         2 . The method for filling blind via holes according to  claim 1 , wherein said ingredient (a) comprises one or more among the substances represented by formulae (II) to (IV) below: 
       HO—(CH 2 —CH 2 —O) a —H  (II) 
       wherein a=5 to 500  
       
         
           
           
               
               
           
         
       
       wherein a=5 to 200  
       
         
           
           
               
               
           
         
       
     
     
         3 . The method for filling blind via holes according to  claim 1 , wherein said ingredient (b) comprises one or more among the substances represented by formulae (V) to (X) below: 
       M—SO 3 —(CH 2 ) a —S—(CH 2 ) b —SO 3 —M  (V) 
       wherein a=3 to 8, b=3 to 8, M is a hydrogen or alkali metal element 
       M—SO 3 —(CH 2 ) a —O—CH 2 —S—CH 2 —O—(CH 2 ) b —SO 3 —M  (VI) 
       wherein a=3 to 8, b=3 to 8, M is a hydrogen or alkali metal element 
       M—SO 3 —(CH 2 ) a —S—S—(CH 2 ) b —SO 3 —M  (VII) 
       wherein a=3 to 8, b=3 to 8, M is a hydrogen or alkali metal element 
       M—SO 3 —(CH 2 ) a —O—CH 2 —S—S—CH 2 —O—(CH 2 ) b —SO 3 —M  (VIII) 
       wherein a=3 to 8, b=3 to 8, M is a hydrogen or alkali metal element  
       
         
           
           
               
               
           
         
       
     
     
         4 . The method for filling blind via holes according to  claim 1 , wherein the concentration of ingredient (a) in the copper sulfate plating bath is from 0.05 to 10 g/liter, and that of ingredient (b) in the copper sulfate plating bath is from 0.1 to 100 mg/liter.  
     
     
         5 . The method for filling blind via holes according to  claim 1 , wherein the blind via hole is from 3 to 50 μm in diameter, from 30 to 100 μm in depth, and has an aspect ratio of 4 to 20, which is the value of dividing the depth by the diameter.  
     
     
         6 . The method for filling blind via holes according to  claim 1 , wherein the ratio of the current density at reverse electrolysis to that at positive electrolysis is from 1 to 10.  
     
     
         7 . The method for filling blind via holes according to  claim 6 , wherein the current density in positive electrolysis is from 0.1 to 20 A/dm 2  and that in reverse electrolysis is from 0.1 to 200 A/dm 2 .  
     
     
         8 . The method for filling blind via holes according to  claim 7 , wherein said substrate is a silicon wafer.  
     
     
         9 . The method for filling blind via holes according to  claim 8 , further comprising forming an insulating film on the inner wall of the blind via holes, prior to said forming of the seed layer for plating, formed in the silicon wafer.  
     
     
         10 . A method for forming an electrode penetrating a substrate, comprising filling the blind via holes with metallic copper provided in the substrate, by the method according to any one of  claims 1  to  9 , and polishing the back of the substrate to obtain the substrate having via holes which are filled with the metallic copper and which penetrate the substrate.