Study of methods for measuring mechanical properties of thin films in microelectromechanical systems (MEMS)

Novel stress measurement methods for determining both tensile and compressive stress and Young´s modulus in surface micromachining are presented by investigating two techniques: (1) Beam Pull-in Voltage (V _PI) and (2) Long Beam Deflection (LBD). Both tensile and compressive stress and Young´s modulus of thin film can be derived by use of the V_PI method. In the LBD method, axial strain of beams can be converted into large transverse deflection which can be measured easily. These techniques have been analyzed, tested experimentally and comparison with other known stress measurement techniques show good consistency. Both techniques have been shown to be quite promising for simple and accurate on-chip thin-film stress measurements