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

Abstract

In the semiconductor industry, economical high-end interposertechnologieswith high thermal conductivity are in high demand. The recently reportedanodic aluminum oxide (AAO) template has limitations of low mechanicalstrength and thermal conductivity due to the amorphous phase. In addition,AAO has microthickness and nanopores, and it is easy to break. Inthis study, the AAO template does not develop a microcrack at hightemperature by controlling the pores on the front and back side ofthe same pore of the AAO, as concluded in the COMSOL simulation. Thenonmicrocrack alpha-AAO template is mechanically robust with highthermal conductivity owing to thermal stress minimization and phasetransformation (anodizing temperature and annealing treatment). Inaddition, anionic contamination components present on the surfaceof the alpha-AAO pores were removed by increasing the temperature,and the properties were investigated. The hardness and thermal conductivityof the alpha-AAO template (8.98 GPa and 13.7 W/(m & BULL;K)) were 3.3and 6.7 times higher than those of bare-AAO (2.74 GPa and 2.08 W/(m & BULL;K)),respectively. Especially, the superior thermal conductivity of alpha-AAOwas confirmed by a thermal imaging camera (TIC). The alpha-AAO templatewith enhanced hardness and thermal conductivity can potentially beused in various applications, such as semiconductor interposer materialsand 6G wireless communication components.