Thermal interface material for integrated circuit package and method of making the same

Abstract

In an embodiment, a thermal interface material (TIM) is provided. The TIM includes first and a second layers of a first transition metal, and a third layer including a plurality of carbon nanotubes supported in a flexible polymer matrix and a second transition metal coupled to sidewalls of carbon nanotubes. The first and second metal layers are in contact with first and second ends of carbon nanotube. The TIM further includes fourth and fifth layers of an alloy material coupled to the first and second metal layers, respectively. The carbon nanotube based TIM including the layers with transition metal allow improved heat transfer from an integrated circuit die to a heat spreader.

What is claimed is: 
     
         1 . A method of manufacturing a thermal interface material (TIM), the method comprising:
 forming a layer having a polymer matrix and a plurality of carbon nanotubes, wherein the layer includes first and second surfaces;   coating at least a portion of a sidewall of at least one carbon nanotube of the plurality of carbon nanotubes;   depositing a transition metal layer on the first and second surfaces of the layer; and   depositing a non-transition metal layer on the transition metal layer.   
     
     
         2 . The method of  claim 1 , wherein the forming comprises:
 growing a film on a substrate, wherein the film comprises the plurality of carbon nanotubes;   dipping the film in a polymer solution to fill interspaces between substantially all the carbon nanotubes of the plurality of carbon nanotubes;   curing the polymer solution in the interspaces; and   etching back the cured polymer solution to expose first and second ends of substantially all the carbon nanotubes of the plurality of carbon nanotubes.   
     
     
         3 . The method of  claim 1 , wherein the coating comprises depositing titanium, nickel, or palladium on at least a portion of a sidewall of at least one carbon nanotube of the plurality of carbon nanotubes. 
     
     
         4 . The method of  claim 1 , wherein the transition metal layer comprises a transition metal selected from the group consisting of: titanium, niobium, and hafnium. 
     
     
         5 . The method of  claim 1 , wherein each carbon nanotube of the plurality of carbon nanotubes is substantially vertically aligned with one or more of the carbon nanotubes of the plurality of carbon nanotubes. 
     
     
         6 . The method of  claim 1 , wherein the transition metal layer comprises a vertical dimension between approximately 0.01 μm to approximately 5 nm. 
     
     
         7 . The method of  claim 1 , wherein the non-transition metal layer comprises a vertical dimension between approximately 0.5 μm to approximately 50 μm. 
     
     
         8 . The method of  claim 1 , wherein the non-transition metal layer comprises an alloy material having a low melting point alloy selected from the group consisting of: indium, tin, indium-tin, gallium, gold, tin-copper, tin-copper-silver, and tin-lead solder. 
     
     
         9 . A thermal interface material (TIM) manufactured by a process comprising the steps of growing a film on a substrate, the film comprising a plurality of carbon nanotubes;
 forming a matrix material to provide flexible support to the plurality of carbon nanotubes;   depositing first and second metal layers on top and bottom surfaces of the film, respectively; and   depositing a third metal layer on at least a portion of a sidewall of at least one carbon nanotube of the plurality of carbon nanotubes.   
     
     
         10 . The TIM of  claim 9 , wherein each of the first and second metal layers comprises a transition metal selected from the group consisting of: titanium, niobium, and hafnium. 
     
     
         11 . The TIM of  claim 9 , wherein the third metal layer comprises a transition metal selected from the group consisting of titanium, nickel, and palladium. 
     
     
         12 . The TIM of  claim 9 , wherein the process further comprises the steps of:
 depositing a first alloy layer on the first metal layer; and   depositing a second alloy layer on the second metal layer.   
     
     
         13 . The TIM of  claim 12 , wherein each of the first and second alloy layers comprises a low melting point alloy selected from the group consisting of indium, tin, indium-tin, gallium, gold, tin-copper, tin-copper-silver, and tin-lead solder. 
     
     
         14 . The TIM of  claim 9 , wherein the first and second metal layers covalently bond with first and second ends, respectively, of substantially all the carbon nanotubes of the plurality of carbon nanotubes. 
     
     
         15 . A method of manufacturing an integrated circuit (IC) package, the method comprising:
 coupling a substrate to a first surface of an IC die;   forming a thermal interface material (TIM), the TIM comprising a layer having a polymer matrix and a plurality of carbon nanotubes;   disposing the TIM on a second surface of the IC die, the first surface and the second surface being opposite to each other; and   coupling a heat spreader to a top surface of the TIM.   
     
     
         16 . The method of  claim 15 , wherein the forming of the TIM comprises:
 forming the layer having the polymer matrix and the plurality of carbon nanotubes;   coating at least a portion of a sidewall of at least one carbon nanotube of the plurality of carbon nanotubes;   depositing a transition metal layer on first and second surfaces of the layer; and   depositing a non-transition metal layer on the transition metal layer.   
     
     
         17 . The method of  claim 16 , wherein the transition metal layer comprises a transition metal selected from the group consisting of titanium, niobium, and hafnium. 
     
     
         18 . The method of  claim 16 , wherein the non-transition metal layer comprises an alloy material having a low melting point alloy selected from the group consisting of: indium, tin, indium-tin, gallium, gold, tin-copper, tin-copper-silver, and tin-lead solder. 
     
     
         19 . The method of  claim 15 , wherein each carbon nanotube of the plurality of carbon nanotubes is substantially vertically aligned with one or more of the carbon nanotubes of the plurality of carbon nanotubes. 
     
     
         20 . The method of  claim 15 , wherein the forming of the TIM comprises:
 growing a film on another substrate, wherein the film comprises the plurality of carbon nanotubes;   dipping the film in a polymer solution to fill interspaces between substantially all the carbon nanotubes of the plurality of carbon nanotubes;   curing the polymer solution in the interspaces; and   etching back the cured polymer solution to expose first and second ends of substantially all the carbon nanotubes of the plurality of carbon nanotubes.