Lateral reaction of polycrystalline silicon film with overlapping aluminum film

Abstract
Remarkable substitution reaction between aluminum and polycrystalline silicon, which occurs below the eutectic temperature (577 °C), has been studied. This reaction proceeds laterally in the polycrystalline silicon film, and the reaction product contains aluminum. In order to elucidate the cause of the rapid reaction, the influences of aluminum volume, substrate materials, and polycrystalline silicon grain size on the reaction rate were investigated. Results indicate that the reaction proceeds preferentially along polycrystalline silicon grain boundaries on SiO2 substrate and depends on silicon solubility and diffusivity in aluminum.