Thermal Characterization of the High-Thermal-Conductivity Dielectrics

Abstract

It has been recognized that future improvements in performance and reliability of the microelectronic devices may only be possible through the use of new high-thermal-conductivity materials for thermal management in compact packaging systems. The diamond-like dielectric materials, in bulk form or thin film configurations are the likely choice, due to their high thermal conductivity and their excellent mechanical and electrical properties. However, the accurate thermal characterization of these materials has proven to be extremely challenging due to variations in fabrication processes and therefore their microstructures, as well as the practical difficulties in measuring small temperature gradients during the thermal characterization process. The variations in microstructure of these materials (e.g., CVD diamond) would manifest into anisotropic, nonhomogeneous, and thickness-dependent thermal properties that may vary by several orders of magnitude. As a result of these complications, a wide range of experimental techniques have been developed over the years, which may or may not be appropriate for thermal characterization of high-thermal-conductivity material of given microstructure and physical dimension. We will describe and critically review the existing thermal-characterization techniques for high-thermal-conductivity dielectric materials. In addition, we propose a number of techniques that are particularly tailored for accurate thermal characterization of diamond, silicon nitride (Si3N4), aluminum nitride (AlN), and silicon carbide (SiC) films and substrates. In each case, specific comments about the experimental technique and procedure, detailed description of the heat transfer process, and sensitivity analysis are provided.