Seedlayer-less gold electroplating on silicon surface for MEMS applications

This paper presents a development and characterization of a novel technology for seedlayer-less gold electroplating. This method allows that a gold film grows directly and selectively on a silicon surface. In the MEMS field, the gold film is increasingly drawing attention for its low electrical resistivity, high physicochemical stability, high biocompatibility and high reflectivity to the infrared ray. Due to low adhesion of the gold, it had been considered that it is difficult to obtain the direct electroplating film on a silicon surface. The two-step gold electroplating method presented here, which contains the first thin electroplating of 0.2 μm with low current density of 0.75 mA/cm2 and following annealing process at 250 °C for 30 min, achieves increasing adhesion and realizes practical gold film on a silicon.