Wafer-level bonding for mechanically reinforced ultra-thin die

Abstract

An embodiment of the present invention is a technique to fabricate a package. A metal sheet having trenches is formed. A thinned wafer supported by a wafer support substrate (WSS) is formed. The metal sheet is bonded to the WSS-supported thinned wafer to form a metal bonded thinned wafer. The thinned wafer is diced to the trenches into die assemblies.

1 - 9 . (canceled) 
     
     
         10 . A package comprising:
 a substrate;   a die assembly attached to the substrate, the die assembly comprising:
 a thin die having a thickness, 
 a first thermal interface material (TIM) deposited on the thin die, and 
 a metal element attached to the first TIM; 
   a second TIM attached to the metal element; and   a heat spreader attached to the substrate and the second TIM, the heat spreader enclosing the die assembly.   
     
     
         11 . The package of  claim 10  further comprising:
 an underfill dispensed between the die assembly and the substrate.   
     
     
         12 . The package of  claim 10  wherein the thickness is less than 75 μm. 
     
     
         13 . The package of  claim 10  wherein the metal element is copper. 
     
     
         14 . The package of  claim 10  wherein the first TIM has thickness less than one-fifth of thickness of the second TIM. 
     
     
         15 . The package of  claim 10  wherein the first TIM has thickness ranging from approximately 3 μm to 10 μm. 
     
     
         16 . The package of  claim 10  wherein the first TIM is made of indium-silver (In—Ag) or tin-copper (Sn—Cu). 
     
     
         17 . The package of  claim 10  wherein the metal element is slightly smaller than the thin die. 
     
     
         18 . A system comprising:
 a front end processing unit to receive and transmit a radio frequency (RF) signal, the RF signal being converted to digital data;   a digital processor coupled to the front end processing unit to process the digital data; and   a memory device coupled to the digital processor, the memory device being packaged in a package, the package comprising:
 a substrate, 
 a die assembly attached to the substrate, the die assembly comprising:
 a thin die having a thickness, 
 a first thermal interface material (TIM) deposited on the thin die, and 
 a metal element attached to the first TIM, 
 
 a second TIM attached to the metal element, and 
 a heat spreader attached to the substrate and the second TIM, the heat spreader enclosing the die assembly. 
   
     
     
         19 . The system of  claim 18  further comprising:
 an underfill dispensed between the die assembly and the substrate.   
     
     
         20 . The system of  claim 18  wherein the thickness is less than 75 μm. 
     
     
         21 . The system of  claim 18  wherein the metal element is copper. 
     
     
         22 . The system of  claim 18  wherein the first TIM has thickness less than one-fifth of thickness of the second TIM. 
     
     
         23 . The system of  claim 18  wherein the first TIM has a thickness ranging from approximately 3 μm to 10 μm. 
     
     
         24 . The system of  claim 18  wherein the first TIM is made of indium-silver (In—Ag) or tin-copper (Sn—Cu). 
     
     
         25 . The system of  claim 18  wherein the metal element is slightly smaller than the thin die.