Mechanically Robust and Thermally Conductive Nano-Porous Anodic Aluminum Oxide Templates via Thermal Stress Minimization and Alpha Phase Transformation for Interposer

In the semiconductor industry, economical high-end interposer technologies with high thermal conductivity are in high demand. The recently reported anodic aluminum oxide (AAO) template has limitations of low mechanical strength and thermal conductivity due to the amorphous phase. In addition, AAO has microthickness and nanopores, and it is easy to break. In this study, the AAO template does not develop a microcrack at high temperature by controlling the pores on the front and back side of the same pore of the AAO, as concluded in the COMSOL simulation. The nonmicrocrack alpha-AAO template is mechanically robust with high thermal conductivity owing to thermal stress minimization and phase transformation (anodizing temperature and annealing treatment). In addition, anionic contamination components present on the surface of the alpha-AAO pores were removed by increasing the temperature, and the properties were investigated. The hardness and thermal conductivity of the alpha-AAO template (8.98 GPa and 13.7 W/(m·K)) were 3.3 and 6.7 times higher than those of bare-AAO (2.74 GPa and 2.08 W/(m·K)), respectively. Especially, the superior thermal conductivity of alpha-AAO was confirmed by a thermal imaging camera (TIC). The alpha-AAO template with enhanced hardness and thermal conductivity can potentially be used in various applications, such as semiconductor interposer materials and 6G wireless communication components.