Layer Configurations for Al-Ge Eutectic Wafer Bonding

Different layer configurations for Al-Ge eutectic bonding are investigated using SAM and X-SEM. These configurations are single layer Al and Ge, double layer layer Al on top of Ge, or double layer Ge on top of Al. The Ge on top of Al configuration leads to the best SAM results. The effect of native oxide presence on top or between the layers is investigated using X-SEM. The results indicate the presence of one or more interfaces for every layer configuration. The native oxide could prevent the eutectic from mixing across the bonding interface. In this regard, Al oxide seems the most problematic.