Improvement of Au cantilever fabrication process with Cu as a sacrificial layer

This paper addresses several challenges in the formation of an Au cantilever taking Cu as a sacrificial layer. With respect to the Cu wet etch process, an etchant containing HAC and H₂O₂ works most effectively in anchor corrosion process and an etchant involving FeCl₂ and HCl achieves better performance in the Cu sacrificial layer release process. Moreover, we probe into the wrinkle phenomenon of the electroplated Au structural layer immediately upon the Cu sacrificial layer, adjust the electroplating recipe such as the stirring speed and temperature, and try to add nickel resist layer for an improvement as well. We analyze the wrinkle formation process and simulate the position of the wrinkle. Besides, we deeply research the influence of current efficiency, residual stress and electroplate rate caused by reducing temperature. To restrain the influence of the temperature reduction, pulse current source was used in the electroplating process and we get a long and straight cantilever ultimately.