Surface Cleaning of Gold Structure by Annealing during Fabrication of Microelectromechanical System Devices

Abstract

We describe a technique for cleaning a gold surface using a dry process during the fabrication of microelectromechanical system (MEMS) devices. After exposure to oxygen plasma for ashing of the organic contaminants or etching of a sacrificial-layer film, the gold surface is oxidized. On such an oxidized surface, there are different incubation periods at different places, which give rise to nonuniform thickness in electroplating as well as in electrodeposition. A surface analysis by X-ray photoelectron spectroscopy (XPS) revealed that annealing at a temperature of over 260 °C causes oxygen to desorb from the gold oxide. The application of this cleaning technique before electroplating or electrodeposition leads to uniform growth.