Stress control structures for microelectromechanical systems using structural mechanics approach

A method of stress control in microelectromechanical systems (MEMS) devices is presented that consists of creating counterbalancing structures to position stressed layers at the neutral plane of the device, eliminating the bending momentum acting on the device. Upon metallization, many MEMS elements such as silicon membranes show substantial bow under the stress developed as a result of the difference in the thermal expansion coefficients of a metal and silicon. The proposed membranes with the counterbalancing structures remain flat in the entire test temperature range (25-150 degrees C). The method gives material-independent solution to stress-induced curvature problems in a variety of ultrathin devices. (c) 2006 American Institute of Physics.