Manufacturing method of ultra-large copper grains without heat treatment

Abstract

A film of single crystal copper is manufactured by means of electrodeposition without heat treatment. The grains of the single crystal copper have an average size of at least 10 μm. The electrolytic solution used in the method contains chloride ions, a wetting agent, sulfuric acid, CuSO4.5H2O and alkanesulfonate sulfide. The ultra-large copper grains of the present invention contain very few impurities and thus possess low resistance, high conductivity, shining appearance and anti-fingerprint property.

We claim: 
     
         1 . A manufacturing method of ultra-large copper grain without heat treatment, comprising:
 A. providing an electrodeposit equipment which comprises an anode, a cathode, an electrolytic solution, a power unit, a temperature controller and a mixer; wherein the anode and the cathode respectively connect to the power unit and are immersed in the electrolytic solution; the temperature controller contacts with the electrolytic solution to control the electrolytic solution at 25-55° C.; the mixer agitates the electrolytic solution; and the electrolytic solution is obtained by mixing and dissolving chloride ions, wetting agent, sulfuric acid, copper sulfate and sulfur-containing compound having the formula (1) together in deionized water,
   R 1 —S—C n H 2n —R 2  
 
 wherein R 1 ═—H, —S—C n H 2n —R 2  or —C n H 2n —R 2 ;
 R 2 ═SO 3   − , PO 4   −  or COO − ; 
 n=2-10; 
 
   B. performing an electrodeposition process using the electrodeposit equipment with a current density of 1-80 A/dm 2  to deposit ultra-large single crystal copper grains having an average size of at least 10 μm to form a layer of copper grains on a surface of the cathode.   
     
     
         2 . The method of  claim 1 , wherein the sulfur-containing compound is alkanesulfonate sulfide (R—S—C n H 2n —SO 3   − ). 
     
     
         3 . The method of  claim 1 , wherein the sulfur-containing compound is selected from the group consisting of 3-Mercaptopropanesulfonate (MPS), Bis-(3-sulfopropyl)-disulfide (SPS), 3-(2-Benzthiazolylthio)-1-propanesulfonate (ZPS), 3-(N,N-Dimethylthiocarbamoyl)-thiopropanesulfonate (DPS), (O-Ethyldithiocarbonato)-S-(3-sulfopropyl)-ester (OPX), 3-[(Amino-iminomethyl)thio]-1-propanesulfonate (UPS) and 3,3-Thiobis(1-propanesulfonate (TBPS). 
     
     
         4 . The method of  claim 1 , wherein the sulfur-containing compound has a concentration of 0.1-5 ppm in the electrolytic solution. 
     
     
         5 . The method of  claim 4 , wherein the copper sulfate in the electrolytic solution has a concentration of 125-320 g/L. 
     
     
         6 . The method of  claim 5 , wherein the sulfuric acid has a concentration of 17.6-176 g/L in the electrolytic solution. 
     
     
         7 . The method of  claim 6 , wherein the chloride ions have a concentration of 30-60 ppm in the electrolytic solution. 
     
     
         8 . The method of  claim 7 , wherein the wetting agent is polyethylene glycol (PEG) having a molecular weight of 200-2000 and a concentration of 10-200 ppm in the electrolytic solution. 
     
     
         9 . The method of  claim 1 , wherein the anode and the cathode are separated from each other by a distance of 1-12 cm. 
     
     
         10 . The method of  claim 1 , wherein the mixer is a jet mixer having a flow rate of 9-45 cm/s. 
     
     
         11 . A copper film manufactured by the method of  claim 1 , comprising a plurality of the ultra-large single crystal copper grains having an average size of at least 10 μm. 
     
     
         12 . An electrolytic solution employed in a manufacturing method of ultra-large copper grains without heat treatment, comprising:
 chemical components including chloride ions, a wetting agent, sulfuric acid, copper sulfate and a sulfur-containing compound having the formula (1),
   R 1 —S—C n H 2n —R 2    (1),
 
 wherein R 1 ═—H, —S—C n H 2n —R 2  or —C n H 2n —R 2 ;
 R 2 ═SO 3   − , PO 4   −  or COO − ; 
 n=2-10; and 
 
   deionized water for mixing and dissolving the chemical components therein;   wherein the manufacturing method performs an electrodeposition process in the electrolytic solution to deposit ultra-large single crystal copper grains having an average size of at least 10 μm to form a layer of copper grains on a work electrode.   
     
     
         13 . The electrolytic solution of  claim 12 , wherein the sulfur-containing compound is alkanesulfonate sulfide (R—S—C n —H 2n —SO 3   − ). 
     
     
         14 . The electrolytic solution of  claim 12 , wherein the sulfur-containing compound is selected from the group consisting of 3-Mercaptopropanesulfonate (MPS), Bis-(3-sulfopropyl)-disulfide (SPS), 3-(2-Benzthiazolylthio)-1-propanesulfonate (ZPS), 3-(N,N-Dimethylthiocarbamoyl)-thiopropanesulfonate (DPS), (O-Ethyldithiocarbonato)-S-(3-sulfopropyl)-ester (OPX), 3-[(Amino-iminomethyl)thio]-1-propanesulfonate (UPS) and 3,3-Thiobis(1-propanesulfonate (TBPS). 
     
     
         15 . The electrolytic solution of  claim 12 , wherein the sulfur-containing compound has a concentration of 0.1-5 ppm in the electrolytic solution. 
     
     
         16 . The electrolytic solution of  claim 15 , wherein the copper sulfate in the electrolytic solution has a concentration of 125-320 g/L. 
     
     
         17 . The electrolytic solution of  claim 16 , wherein the sulfuric acid has a concentration of 17.6-176 g/L in the electrolytic solution. 
     
     
         18 . The electrolytic solution of  claim 16 , wherein the chloride ions has a concentration of 30-60 ppm in the electrolytic solution. 
     
     
         19 . The electrolytic solution of  claim 18 , wherein the wetting agent is polyethylene glycol (PEG) having a molecular weight of 200-2000 and a concentration of 10-200 ppm in the electrolytic solution. 
     
     
         20 . A connecting structure of electric elements including the ultra-large copper grains manufactured by the manufacturing method of  claim 1 , comprising:
 a copper pad including the ultra-large copper grains having an average size of at least 10 μm;   a solder unit on a surface of the pad; and   an intermetallic compound (IMC) layer formed between the copper pad and the solder unit, wherein no void is present at the interface between the copper pad and the IMC, and between the IMC and the solder unit.