3-Omega Measurements of Vertically Oriented Carbon Nanotubes on Silicon

X. Jack Hu, Intel Corporation
Antonio A. Padilla, Mechanical Engineering Department, Stanford University
Jun Xu, Birck Nanotechnology Center, School of Mechanical Engineering, Purdue University
Timothy S. Fisher, Birck Nanotechnology Center, School of Mechanical Engineering, Purdue University
Kenneth E. Goodson, Mechanical Engineering Department, Stanford University

Abstract

An exploratory thermal interface structure, made of vertically oriented carbon nanotubes directly grown on a silicon substrate, has been thermally characterized using a 3-omega method. The effective thermal conductivities of the carbon nanotubes (CNT) sample, including the effects of voids, are found to be 74 W/mK to 83 W/mK in the temperature range of 295K to 323K, one order higher than that of the best thermal greases or phase change materials. This result suggests that the vertically oriented CNTs potentially can be a promising next-generation thermal interface solution. However, fairly large thermal resistances were observed at the interfaces between the CNT samples and the experimental contact. Minimizing these contact resistances is critical for the application of these materials.