Copper-containing C4 ball-limiting metallurgy stack for enhanced reliability of packaged structures and method of making same

Abstract

The invention relates to a ball-limiting metallurgy stack for an electrical device that contains at least one copper layer disposed upon a Ti adhesion metal layer. The ball-limiting metallurgy stack resists Sn migration toward the upper metallization of the device.

1 . A process comprising: 
 forming a metallization over a substrate;    forming a metal adhesion first layer above and on the metallization;    forming a metal second layer above and on the metal adhesion first layer;    forming a metal third layer above and on the metal second layer;    forming a solder bump above and on the metal third layer,    wherein the forming the metal second layer and the forming the metal third layer comprises    sputtering a copper metal second layer over the metal adhesion first layer under conditions to impart a compressive stress therein; and    plating a copper stud through a mask that is disposed over the metal second layer.    
   
   
       2 . The process of  claim 2 , wherein the forming a metal adhesion first layer comprises 
 sputtering a composition over the metallization under conditions to impart a compressive stress in the metal adhesion first layer, wherein the composition is selected from the group consisting of Ti, TiW, W, and Cr.    
   
   
       3 . The process according to  claim 1 , further comprising: 
 forming an electrically conductive bump above and on the metal third layer.    
   
   
       4 . A process comprising: 
 forming a copper pad over a metal-six (M6) metallization;    sputtering a Ti metal adhesion first layer above and on the metallization;    sputtering a metal second layer above and on the Ti metal adhesion first layer;    forming a metal third layer above and on the metal second layer;    forming a solder bump above and on the metal third layer, wherein forming a metal third layer comprises:    electroplating a copper stud over the metal second layer.    
   
   
       5 . The process of  claim 4 , wherein the copper stud has a thickness in a range from about 5 micrometers to about 15 micrometers.  
   
   
       6 . The process of  claim 4 , wherein the metal second layer has a thickness in a range from about 1,000 angstroms to about 5,000 angstroms.  
   
   
       7 . The process of  claim 4 , wherein sputtering the Ti metal adhesion first layer above and on the metallization comprises: 
 sputtering a Ti composition over the metallization, wherein the Ti composition has a thickness in a range from about 500 angstroms to about 4,000 angstroms.