Method of forming a micro solder ball for use in C4 bonding process

Abstract

A method of forming micro solder balls for use in a C4 process is described. The solder balls are formed by laying down a peel-away photoresist layer, forming holes in the photoresist layer to expose electrical contacts, depositing a solder layer over the photoresist, forming solder areas in the holes and then, using a tape liftoff process to remove the solder layer and photoresist layer while leaving solder areas in the holes. The solder areas are then heated to allow solder balls to form.

1 - 39 . (canceled)  
   
   
       40 . A semiconductor device comprising: 
 a semiconductor structure having at least one metal contact formed on a surface thereof;    a first insulator layer overlying said at least one metal contact;    at least one metal pad overlying said first insulator layer and in contact with said at least one metal contact;    a second insulator layer overlying said at least first one metal pad; and,    at least one solder contact formed in the second insulator and in contact with said at least one metal pad, said solder contact having a diameter less than 100 microns.    
   
   
       41 - 42 . (canceled)  
   
   
       43 . The semiconductor device of  claim 40 , wherein the solder contacts have a diameter less than 10 microns.  
   
   
       44 . The semiconductor device of  claim 40 , wherein the solder contacts have a diameter of approximately 2 microns.  
   
   
       45 . The semiconductor device of  claim 40 , wherein said at least one metal contact is connected to said at least one metal pad by a via hole formed in the first insulator.  
   
   
       46 . The semiconductor device of  claim 40 , wherein the at least one solder contact extends from a top surface of the second insulator to the metal pad by a through hole formed in the second insulator.  
   
   
       47 . The semiconductor device of  claim 40 , wherein the at least one metal pad lies at least partially overtop of the at least one metal contact.  
   
   
       48 . The semiconductor device of  claim 40 , wherein the semiconductor device is an integrated circuit chip.  
   
   
       49 . The semiconductor device of  claim 40 , wherein the semiconductor device is an integrated circuit wafer.  
   
   
       50 . The semiconductor device of  claim 40 , wherein the semiconductor device is bonded to a module substrate.  
   
   
       51 . The semiconductor device of  claim 40 , wherein the semiconductor device is bonded to a circuit board.  
   
   
       52 - 67 . (canceled)  
   
   
       68 . The semiconductor device of  claim 40 , wherein said first insulator layer is at least 2 microns thicker than said at least one metal contact.  
   
   
       69 . The semiconductor device of  claim 40 , wherein said metal pad comprises a metal stack with four different metal levels.  
   
   
       70 . The semiconductor device of  claim 69 , wherein said metal levels comprise Zirconium, Nickel, Copper and Gold.  
   
   
       71 . A semiconductor device formed on a semiconductor substrate having at least one metal contact formed thereon, said semiconductor device comprising: 
 a first insulator layer overlying said at least one metal contact;    at least one metal pad overlying said first insulator layer and in contact with said at least one metal contact;    a second insulator layer overlying said at least first one metal pad; and    at least one solder contact formed in the second insulator and in contact with said at least one metal pad, said solder contact having a diameter between 2 and 100 microns.    
   
   
       72 . The semiconductor device of  claim 71 , wherein said at least one solder contact has a diameter of approximately 2 microns.  
   
   
       73 . The semiconductor device of  claim 40  wherein the solder contacts have a diameter less than 50 microns.  
   
   
       74 . The semiconductor device of  claim 40  wherein the solder contacts have a diameter less than 25 microns.