Tailoring material properties of electrochemically deposited Al film from chloroaluminate ionic liquid for microsystem technology using pulsed deposition

Abstract

To practically utilize an electrochemically deposited Al film in microsystems, its material properties have to be elucidated, along with the influence of different deposition conditions. In this study, microstructure, electrical, mechanical and thermal properties of electrochemically deposited Al film from a chloroaluminate ionic liquid electrolyte are comprehensively investigated. The nanoindentation hardness and elastic modulus of the film varied between 486–908 MPa and 41–102 GPa, respectively, depending on the deposition condition. The electrical resistivity and the coefficient of thermal expansion varied between 51–160 nΩ m and 2–20 ppm/K, respectively. The results are compared to those of Al thin films deposited using other techniques. The characterized properties were found to be associated to the microstuctures of the deposits, which can be tailored by the deposition conditions. The microstructures of the deposits were comprehensively characterized by cross-sectional scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) spectroscopy. These results are useful as a design guide for the future applications of the film.