Galvanic effects in Si-based microelectromechanical systems: Thick oxide formation and its implications for fatigue reliability

Nanometer-scale reaction layers have a profound impact on the fracture and fatigue resistance of the Si films used in microelectromechanical systems (MEMS). This letter presents experimental evidence that thick (i.e., greater than 10 nm) oxides can form at room temperature during manufacturing due to a galvanic effect between n(+)-type Si and Au. The growth of such oxides in concentrated HF solutions that are usually associated with oxide dissolution can be predicted from the measured current density-voltage (i-V) behavior and geometry of the galvanic couple. These results can account for unexplained findings in the literature and can be used to improve the performance of MEMS. (c) 2005 American Institute of Physics.