Methods of fabricating a composite carbon nanotube thermal interface device
Embodiments of a composite carbon nanotube structure comprising a number of carbon nanotubes disposed in a matrix comprised of a metal or a metal oxide. The composite carbon nanotube structures may be used as a thermal interface device in a packaged integrated circuit device.
1. A method comprising:
forming a sacrificial layer on a substrate;
forming a metal layer on the sacrificial layer;
anodizing the metal layer to form a layer of a porous metal oxide;
forming carbon nanotubes in pores of the porous metal oxide layer; and
separating the porous metal oxide layer and carbon nanotubes from the sacrificial layer and the substrate to form a free-standing composite carbon nanotube (CNT) structure.
2. The method of claim 1 , further comprising removing excess metal oxide material from the pores of the porous metal oxide layer prior to forming the carbon nanotubes.
3. The method of claim 2 , wherein the pores extend through the porous metal oxide layer into the sacrificial layer.
4. The method of claim 1 , further comprising depositing a catalyst in the pores of the porous metal oxide layer prior to forming the carbon nanotubes.
5. The method of claim 4 , wherein the catalyst comprises iron, nickel, cobalt, rhodium, platinum, or yttrium.
6. The method of claim 1 , wherein separating the porous metal oxide layer and carbon nanotubes from the sacrificial layer and substrate comprises dissolving the sacrificial layer.
7. The method of claim 6 , wherein the sacrificial layer is dissolved in a solution including an acid.
8. The method of claim 7 , wherein the acid comprises phosphoric acid, succinic acid, or sulfuric acid.
9. The method of claim 7 , wherein the sacrificial layer is dissolved under application of an anodic potential.
10. The method of claim 1 , further comprising attaching the composite CNT structure to a component.
11. The method of claim 10 , wherein the component comprises a semiconductor wafer, an integrated circuit die, a heat spreader, or a heat sink.
12. The method of claim 10 , wherein attaching the composite CNT structure to the component comprises attaching the composite CNT structure to the component using a low melting point metal alloy.
13. The method of claim 12 , wherein the low melting point metal alloy comprises a solder.
14. The method of claim 10 , wherein attaching the composite CNT structure to the component comprises compressing the composite CNT structure against the component.
15. The method of claim 14 , wherein the composite CNT structure is compressed against the component under a pressure in a range up to approximately 10 Kg/cm 2 .
16. The method of claim 1 , wherein the composite CNT structure has a thickness in a range of approximately 2 μm to 20 μm.
17. The method of claim 1 , wherein the carbon nanotubes are formed to a height extending above an upper surface of the porous metal oxide layer.
18. The method of claim 1 , wherein the carbon nanotubes are formed by chemical vapor deposition (CVD) or plasma enhanced CVD.
19. The method of claim 1 , wherein the metal layer comprises aluminum and the porous metal oxide layer comprises aluminum oxide.
20. The method of claim 1 , wherein the sacrificial layer comprises vanadium, titanium, or tungsten.
21. The method of claim 1 , wherein the metal layer is anodized under a positive voltage and in the presence of a solution including an acid.
22. The method of claim 21 , wherein the acid comprises one of phosphoric acid, succinic acid, sulfuric acid, and oxalic acid.
23. The method of claim 21 , wherein the positive voltage comprises a voltage in a range of approximately 1 to 60 volts.
24. A method comprising:
forming a sacrificial layer on a substrate;
forming a layer of a porous material on the sacrificial layer;
forming carbon nanotubes in pores of the layer of porous material; and
separating the porous material layer and carbon nanotubes from the sacrificial layer and the substrate to form a free-standing composite carbon nanotube structure.
25. The method of claim 24 , further comprising depositing a catalyst in the pores of the layer of porous material prior to forming the carbon nanotubes.
26. The method of claim 24 , wherein separating the porous material layer and carbon nanotubes from the sacrificial layer and the substrate comprises dissolving the sacrificial layer.