Vacuum Annealing of Gold Electrodes for Surface Cleaning in MEMS Device Fabrication

We developed a dry process for the removal of gold oxide formed during oxygen plasma exposure. This technique features vacuum annealing at over 270degC to desorb oxygen from the gold oxide. This vacuum annealing eliminates the incubation period to achieve the conformal film growth.However, when gold and HCl(aq) soluble material such as aluminum coexist on the same surface or when there are fragile microstructures for wet processes after release, this dipping cannot be applied because it can damage the surface or microstructures in the MEMS fabrication process. The profile for vacuum annealing was found to be consistent with one for HCl(aq) dipping. Moreover, there was no incubation period, meaning that vacuum annealing indeed removes the gold oxide. We can conclude that the vacuum annealing of the gold oxide surface is a promising way to obtain the pure gold surface.