Circuit board, semiconductor device, and method of manufacturing semiconductor device

Abstract

There is provided a circuit board to which a solder ball composed of a lead (Pb)-free solder is to be connected, a semiconductor device including an electrode and a solder ball composed of a lead (Pb)-free solder disposed on the electrode, and a method of manufacturing the semiconductor device, in which mounting reliability can be improved by enhancing the bonding strength (adhesion strength) between the solder ball composed of a lead (Pb)-free solder and the electrode.

1 . A circuit board comprising:
 a base composed of an insulating material; and   an electrode disposed on the base and connected to a solder ball composed of a lead free material, the electrode comprising:   a first layer containing copper as a main component and formed on the base;   a second layer containing nickel as a main component and formed on the first layer; and   a third layer containing an alloy of tin and nickel as a main component and formed on the second layer.   
   
   
       2 . The circuit board according to  claim 1  further comprising,
 a fourth layer containing tin as a main component and formed on the third layer.   
   
   
       3 . The circuit board according to  claim 1 , wherein the third layer has a thickness of 2 micrometers to 3 micrometers. 
   
   
       4 . The circuit board according to  claim 1 , wherein the solder ball contains tin and copper. 
   
   
       5 . The circuit board according to  claim 4 , wherein the solder ball further contains silver. 
   
   
       6 . A semiconductor device comprising
 a base;   a first electrode formed on the base; and   a solder ball composed of lead free solder and formed on the first electrode,   wherein the first electrode comprises:
 a first layer containing copper as a main component; 
 a second layer containing nickel as a main component and formed on the first layer; and 
 a third layer containing an alloy of tin and nickel as a main component and formed on the second layer. 
   
   
   
       7 . The semiconductor device according to  claim 6 , wherein the solder ball contains tin and copper. 
   
   
       8 . The semiconductor device according to  claim 7 , wherein the solder ball further contains silver. 
   
   
       9 . The semiconductor device according to  claim 7 , wherein an alloy of tin, nickel, and copper is formed between the solder ball and the third layer. 
   
   
       10 . The semiconductor device according to  claim 6 , wherein the solder ball is connected to a circuit board. 
   
   
       11 . The semiconductor device according to  claim 10 , wherein the circuit board comprises a second electrode, the second electrode comprising:
 a base;   a fourth layer containing copper as a main component and formed on the base;   a fifth layer containing nickel as a main component and formed on the fourth layer; and   a sixth layer containing an alloy of tin and nickel as a main component and formed on the fifth layer.   
   
   
       12 . A method for manufacturing a semiconductor device, the method comprising steps of:
 forming a first electrode on a base; and   forming a solder ball composed of lead free solder on the first electrode,   wherein the step of forming the first electrode comprises steps of:
 forming a first layer containing copper as a main component on the base; 
 forming a second layer containing nickel as a main component on the first layer; 
 forming a third layer containing tin as a main component on the second layer; and 
 forming a alloy layer of the second layer and the third layer by a heat treatment after the step of forming the third layer. 
   
   
   
       13 . The method for manufacturing a semiconductor device according to  claim 12 , wherein the heat treatment is performed at a temperature, the temperature being equal to or higher than a melting point of the tin. 
   
   
       14 . The method for manufacturing a semiconductor device according to  claim 12 , wherein the steps of forming the first layer and forming the second layer are performed by an electroless plating. 
   
   
       15 . The method for manufacturing a semiconductor device according to  claim 12 , wherein the solder ball contains tin and copper. 
   
   
       16 . The method for manufacturing a semiconductor device according to  claim 15 , wherein the solder ball further contains silver. 
   
   
       17 . The method for manufacturing a semiconductor device according to  claim 12 , wherein an alloy of tin, nickel, and copper is formed between the solder ball and the first electrode by the step of the solder ball. 
   
   
       18 . The method for manufacturing a semiconductor device according to  claim 12 , further comprising a step of forming a fourth layer containing gold as a main component between the steps of forming the second layer and forming the third layer. 
   
   
       19 . The method for manufacturing a semiconductor device according to  claim 12 , further comprising a step of connecting the solder ball to a circuit board. 
   
   
       20 . The method for manufacturing a semiconductor device according to  claim 12 , wherein the circuit board comprising:
 a base; and   a second electrode formed on the base,   wherein the second electrode comprising:
 a fifth layer containing copper as a main component and formed on the base; 
 a sixth layer containing nickel as a main component and formed on the fifth layer; 
 and a seventh layer containing an alloy of tin and nickel as a main component and formed on the sixth layer.