Stacked Semiconductor Package having Adhesive/Spacer Structure and Insulation

Abstract

Stacked semiconductor assemblies in which a device such as a die, or a package, or a heat spreader is stacked over a first wire-bonded die. An adhesive/spacer structure is situated between the first wire-bonded die and the device stacked over it, and the device has an electrically non-conductive surface facing the first wire-bonded die. That is, the first die is mounted active side upward on a first substrate and is electrically interconnected to the substrate by wire bonding; an adhesive/spacer structure is formed upon the active side of the first die; and a device such as a die or a package or a heat spreader, having an electrically nonconductive side, is mounted upon the adhesive/spacer structure with the electrically nonconductive side facing the first wire bonded die. The side of the device facing the first wire bonded die may be made electrically nonconductive by having an electrically insulating layer, such as a dielectric film adhesive. Also, methods for making the assemblies are disclosed.

1 . A stacked semiconductor assembly comprising: 
 a first die having a first surface bounded by a periphery and having bond pads at the first surface;    wires bonded to and extending from the bond pads outwardly past the periphery, the wires extending to a maximum height h above the first die;    a package, comprising a package die mounted to and electrically interconnected with a die attach surface of a package substrate, the package having an electrically non-conductive second surface positioned opposite the die attach surface;    the first die and the package defining a first region therebetween;    an adhesive/spacer structure within the first region, the adhesive/spacer structure contacting the first and second surfaces and adhering the first die and the package to one another at a chosen separation, the adhesive/spacer structure comprising spacer elements within an adhesive.    
     
     
         2 . The assembly according to  claim 1  wherein the wires comprise a plurality of sets of generally parallel wires, said plurality of sets of generally parallel wires defining a plurality of wire span portions of the first region.  
     
     
         3 . The assembly according to  claim 1  wherein the wires comprise a set of generally parallel wires, said set of generally parallel wires defining a wire span portion of the first region.  
     
     
         4 . The assembly according to  claim 3  wherein the adhesive/spacer structure is located at other than the wire span portion of the first region.  
     
     
         5 . The assembly according to  claim 4  wherein said adhesive is located at the wire span portion of the first region.  
     
     
         6 . The assembly according to  claim 5  wherein the spacer elements are sized so as not to fit between the generally parallel wires.  
     
     
         7 . The assembly according to  claim 3  wherein the spacer elements are located at other than the wire span portion of the first region.  
     
     
         8 . The assembly according to  claim 1  wherein the adhesive/spacer structure defines first and second spaced-apart adhesive/spacer structure regions.  
     
     
         9 . The assembly according to  claim 1  wherein the first die has a length and a width and a central region.  
     
     
         10 . The assembly according to  claim 9  wherein the first die comprises a center-bonded die with at least some of said die pads positioned at the central region.  
     
     
         11 . The assembly according to  claim 10  wherein at least one of the spacer elements is positioned within the central region.  
     
     
         12 . The assembly according to  claim 1  wherein the spacer elements have a height H with H being at least about equal to h.  
     
     
         13 . The assembly according to  claim 12  wherein H is greater than h.  
     
     
         14 . The assembly according to  claim 12  wherein H is at least about 10% greater than h.  
     
     
         15 . The assembly according to  claim 1  wherein the spacer elements are generally ellipsoidal.  
     
     
         16 . The assembly according to  claim 15  wherein the spacer elements are flattened spheres.  
     
     
         17 . The assembly according to  claim 15  wherein the spacer elements are about 30 um-250 um in diameter.  
     
     
         18 . The assembly according to  claim 1  wherein the spacer elements are all substantially the same size.  
     
     
         19 . The assembly according to  claim 1  wherein the spacer elements comprise an organic and pliable solid material.  
     
     
         20 . The assembly according to  claim 1  wherein the spacer elements comprise at least PTFE.  
     
     
         21 . The stacked semiconductor assembly of  claim 1  wherein the package is oriented so that the die attach side of the upper package substrate faces toward the first die.  
     
     
         22 . The assembly of  claim 1  wherein the upper package is oriented so that electrically non-conductive second surface of the upper package substrate faces toward the first die.  
     
     
         23 . Stacked semiconductor packages comprising the assembly of  claim 1 .  
     
     
         24 . A method for adhering a die and a package to one another at a chosen separation in a stacked semiconductor package, the method comprising: 
 selecting an adhesive/spacer material having spacer elements within an adhesive;    depositing the adhesive/spacer material onto a first surface of a first die, the first die having a first surface bounded by a periphery, bond pads at the first surface, and wires bonded to and extending from the bond pads outwardly past the periphery, the wires extending to a maximum height h above the first die, the wires comprising a set of generally parallel wires, the set of generally parallel wires defining a wire span portion of the first surface;    selecting a package having an electrically non-conductive surface; and 
 locating the electrically non-conductive surface of the package opposite the first surface of the first die and in contact with the adhesive/spacer material there between thereby securing the package and the first die to one another at a chosen separation, the wire span portion of the first surface defining a wire span region between the first and second surfaces.  
   
     
     
         25 . The method according to  claim 24  further comprising preventing any adhesive/spacer material from entering the wire span region.  
     
     
         26 . The method according to  claim 24  wherein the preventing step comprises using spacer elements sized so as not to fit between the generally parallel wires.  
     
     
         27 . The method according to  claim 24  wherein the depositing step is carried out a manner to prevent any adhesive/spacer material from entering the wire span region.  
     
     
         28 . The method according to  claim 24  wherein the selecting step is carried out to select spacer elements having the same size and shape.  
     
     
         29 . The method according to  claim 24  wherein the depositing step is carried out with the first die having a length and a width and a central region.  
     
     
         30 . The method according to  claim 29  wherein the depositing step is carried out with the first die comprising a center-bonded die with at least some of said die pads positioned at the central region.  
     
     
         31 . The method according to  claim 30  wherein depositing step comprises positioning at least some of the adhesive/spacer material within the central region so that at least one spacer element is positioned within the central region.  
     
     
         32 . The method according to  claim 24  wherein the adhesive/spacer material selecting step comprises selecting spacer elements having a height H with H being at least about equal to h.  
     
     
         33 . The method according to  claim 32  wherein the spacer elements selecting step comprises selecting spacer elements in which H is greater than h.  
     
     
         34 . The method according to  claim 32  wherein the spacer elements selecting step comprises determining an allowance for manufacturing tolerance buildup and selecting spacer elements so that H is equal to h plus the allowance for the manufacturing tolerance buildup.  
     
     
         35 . The method according to  claim 32  wherein the spacer elements selecting step comprises determining an allowance for manufacturing tolerance buildup and selecting spacer elements so that H is greater than h plus the allowance for the manufacturing tolerance buildup.  
     
     
         36 . The method according to  claim 32  wherein the spacer elements selecting step comprises selecting spacer elements so that H is at least about 10% greater than h.