Wafer Level Stacked Die Packaging

Abstract

A stacked die package in which an adhesive pad separates a bottom die from a top die. The pad may be in the form of a wall of adhesive about a central hollow area. The bottom die is attached to a base with a low temperature curing adhesive or a snap cure adhesive.

1 . A stacked die package comprising:
 a first microelectronic semiconductor die;   an adhesive pad atop the die;   a second microelectronic semiconductor die affixed atop the adhesive pad; and   a base on which the first microelectronic semiconductor die is attached by an adhesive that cures at a lower temperature than the adhesive in the adhesive pad.   
     
     
         2 . The stacked die package of  claim 1 , further comprising wire bonds connected between a top surface of the first microelectronic semiconductor die and the base. 
     
     
         3 . The stacked die package of  claim 2 , further comprising wire bonds connected between a top surface of the second microelectronic semiconductor die and the base. 
     
     
         4 . The stacked die package of  claim 3 , further comprising nonconductive material molded over the first and second semiconductor dies. 
     
     
         5 . The stacked die package of  claim 4 , further comprising conductive balls attached to a bottom surface of the base. 
     
     
         6 . The stacked die package of  claim 1 , wherein the adhesive pad forms a perimeter about a hollow area centrally disposed above the die. 
     
     
         7 . The stacked die package of  claim 6 , wherein the adhesive pad is in the shape of a rectangular wall. 
     
     
         8 . The stacked die package of  claim 6 , wherein the adhesive pad has a width on the die and a thickness from the die to a top of the pad, wherein a ratio of the thickness to the width is at least 1:1 and the second microelectronic semiconductor die is separated from the first microelectronic semiconductor die by the wall thickness. 
     
     
         9 . The stacked die package of  claim 1 , wherein the adhesive attaching the first microelectronic semiconductor die to the base comprises a low temperature curing adhesive, which cures at temperatures between 125° C. and 150° C. 
     
     
         10 . A stacked die package comprising:
 a first microelectronic semiconductor die;   an adhesive pad atop the die;   a second microelectronic semiconductor die affixed atop the adhesive pad; and   a base on which the first microelectronic semiconductor die is attached by a snap cure adhesive, which cures more quickly than the adhesive in the adhesive pad.   
     
     
         11 . The stacked die package of  claim 10 , further comprising wire bonds connected between a top surface of the first microelectronic semiconductor die and the base. 
     
     
         12 . The stacked die package of  claim 11 , further comprising wire bonds connected between a top surface of the second microelectronic semiconductor die and the base. 
     
     
         13 . The stacked die package of  claim 12 , further comprising nonconductive material molded over the first and second semiconductor dies. 
     
     
         14 . The stacked die package of  claim 13 , further comprising conductive balls attached to a bottom surface of the base. 
     
     
         15 . The stacked die package of  claim 10 , wherein the adhesive pad forms a perimeter about a hollow area centrally disposed above the die. 
     
     
         16 . The stacked die package of  claim 15 , wherein the adhesive pad is in the shape of a rectangular wall. 
     
     
         17 . The stacked die package of  claim 15 , wherein the adhesive pad has a width on the die and a thickness from the die to a top of the wall, wherein a ratio of the thickness to the width is at least 1:1 and the second microelectronic semiconductor die is separated from the first microelectronic semiconductor die by the wall thickness.