Packaging Structure and Method

Abstract

A method of making a semiconductor device includes providing a substrate and forming a conductive layer on the substrate. The conductive layer includes a first metal. A semiconductor die is provided. A bump is formed on the semiconductor die. The bump includes a second metal. The semiconductor die is positioned proximate to the substrate to contact the bump to the conductive layer and form a bonding interface. The bump and the conductive layer are metallurgically reacted at a melting point of the first metal to dissolve a portion of the second metal from an end of the bump. The bonding interface is heated to the melting point of the first metal for a time sufficient to melt a portion of the first metal from the conductive layer. A width of the conductive layer is no greater than a width of the bump.

1 . A method of making a semiconductor device, comprising:
 providing a substrate;   forming a conductive layer on the substrate, the conductive layer including a first metal;   providing a semiconductor die;   forming a bump on the semiconductor die, the bump including gold;   positioning the semiconductor die proximate to the substrate to contact the bump to the conductive layer and form a bonding interface;   heating the bonding interface to a melting point of the first metal for a time sufficient to melt a portion of the first metal from the conductive layer;   metallurgically reacting the bump and the conductive layer at the melting point of the first metal to dissolve a portion of the gold from an end of the bump; and   forming a bonding phase at the bonding interface by mixing a dissolved portion of the gold from the end of the bump with a molten portion of the first metal.   
     
     
         2 . The method of  claim 1 , wherein the first metal includes tin. 
     
     
         3 . The method of  claim 2 , wherein forming the bonding phase further includes mixing the dissolved portion of the gold with the molten portion of the tin to create a Au/Sn alloy composition of about 4:1. 
     
     
         4 . The method of  claim 1 , wherein metallurgically reacting the bump and the conductive layer includes increasing a temperature at the bonding interface above the melting point of the first metal. 
     
     
         5 . The method of  claim 1 , further including forming the bump such that a width of the bump is greater than a width of the conductive layer. 
     
     
         6 . The method of  claim 1 , wherein metallurgically reacting the bump and the conductive layer includes increasing the temperature at the bonding phase. 
     
     
         7 . A method of making a semiconductor device, comprising:
 providing a substrate;   forming a conductive layer on the substrate, the conductive layer including a first metal;   providing a semiconductor die;   forming a bump on the semiconductor die, the bump including a second metal;   positioning the semiconductor die proximate to the substrate to contact the bump to the conductive layer and form a bonding interface;   metallurgically reacting the bump and the conductive layer at a melting point of the first metal to dissolve a portion of the second metal from an end of the bump; and   forming a bonding phase at the bonding interface by mixing a dissolved portion of the second metal from the end of the bump with a molten portion of the first metal.   
     
     
         8 . The method of  claim 7 , further including heating the bonding interface to the melting point of the first metal for a time sufficient to melt a portion of the first metal from the conductive layer. 
     
     
         9 . The method of  claim 8 , wherein the second metal is gold. 
     
     
         10 . The method of  claim 9 , wherein the first metal is tin. 
     
     
         11 . The method of  claim 10 , wherein heating the bonding interface includes heating to a temperature of about 232 degrees C. for a duration of 1 to 2 seconds. 
     
     
         12 . The method of  claim 11 , wherein metallurgically reacting the first and second metals includes mixing the first metal with the second metal in the bonding interface to create a 4:1 alloy composition. 
     
     
         13 . A method of making a semiconductor device, comprising:
 providing a substrate;   forming a conductive layer on the substrate, the conductive layer including a first metal;   providing a semiconductor die;   forming a bump on the semiconductor die, the bump including a second metal;   positioning the semiconductor die proximate to the substrate to contact the bump to the conductive layer and form a bonding interface; and   metallurgically reacting the bump and the conductive layer at a melting point of the first metal to dissolve a portion of the second metal from an end of the bump.   
     
     
         14 . The method of  claim 13 , further including heating the bonding interface to the melting point of the first metal for a time sufficient to melt a portion of the first metal from the conductive layer. 
     
     
         15 . The method of  claim 14 , further including forming a bonding phase at the bonding interface by mixing a dissolved portion of the second metal from the end of the bump with a molten portion of the first metal. 
     
     
         16 . The method of  claim 15 , wherein forming the bonding phase further includes mixing a dissolved portion of the second metal with a molten portion of the first metal. 
     
     
         17 . The method of  claim 16 , wherein mixing the dissolved portion of the second metal with the molten portion of the first metal includes forming an alloy of the first and second metals at the bonding interface. 
     
     
         18 . The method of  claim 16 , wherein heating the bonding interface to the melting point of the first metal includes heating to a temperature of about 232 degrees C. for a duration of 1 to 2 seconds. 
     
     
         19 . The method of  claim 18 , wherein the alloy comprises gold and tin. 
     
     
         20 . The method of  claim 13 , wherein a width of the conductive layer is no greater than a width of the bump. 
     
     
         21 . A semiconductor device, comprising:
 a substrate;   a conductive layer formed on the substrate, the conductive layer including a first metal;   a bump connected to the conductive layer by a bonding phase disposed between the bump and the conductive layer, the bump including a second metal, the bonding phase characterized as an alloy of the first metal and the second metal, wherein the alloy is formed by metallurgically reacting the bump and the conductive layer at a melting point of the first metal to dissolve a portion of the second metal from an end of the bump; and   a semiconductor die that is coupled to an end of the bump opposite the bonding phase.   
     
     
         22 . The semiconductor device of  claim 21 , wherein one of the first and second metals is gold (Au). 
     
     
         23 . The semiconductor device of  claim 22 , wherein another one of the first and second metals is tin (Sn). 
     
     
         24 . The semiconductor device of  claim 23 , wherein a composition of the alloy is about 4:1 Au/Sn. 
     
     
         25 . The semiconductor device of  claim 21 , wherein the bonding phase abuts the bump and the conductive layer.