Excitation and Detection of Vibrations of Micromechanical Structures Using a Dielectric Thin Film

A new technique is introduced for both the excitation and the detection of vibrations of micromechanical skuctures. This makes use of a dielectric thin film, sandwiched between lower and upper electrodes, on top of the vibrating structure. The excitation is based on elecbrostatic forces between the charged electrodes, causing deformation of the dielectric film and bending of the multilayer structure. The detection of the vibration is capacitive, based on the fluctuation of the capacitance due to the deformation of the dielectric film. Experimental results for a stoichiometric silicon nitride dielectric film on top of a silicon cantilever agree well with predicted values. The yield of the electrostatic excitation as well as of the capacitive detection are satisfactory.