Formation of silver films for advanced electrical properties by using aerosol deposition process

Abstract

A simple room temperature aerosol deposition (AD) process was used to fabricate silver thick films for high efficiency metallization that can be applied to decrease the resistance–capacitance delay and increase the signal propagation speed in integrated circuits. To obtain more advanced performance than aerosol-deposited silver films reported in previous studies, experimental parameters (orifice size of nozzle and gas consumption) that could directly affect electrical resistivity were optimized in advance. The proper small orifice size was selected for facilitated reduction of electrical resistivity by activating the percolation effect and making more conduction channels. High gas consumption also reduced the electrical resistivity of the silver films, forming plenty of metal clusters. Using experimental parameters that showed the lowest resistivity, silver thick films were fabricated via the AD process and their properties were analyzed. The results of the X-ray diffraction confirmed that the silver particles underwent impact-induced plastic deformation. As the film thickness was thickened up to 12 scans, the collided particles filled up the rough alumina substrate. After 12 scans, the silver films became densified due to severe plastic deformation of the as-deposited silver particles. Therefore, the growth mechanism suggests that most silver particles in the initial deposition step contribute to mechanical interlocking, and the subsequent particles could lead to film densification.