Visualization of in- and out-of-plane vibrations in a micromechanical RF-resonator

Vibrations in a micromechanical 13.1 MHz bulk acoustic mode silicon resonator are imaged utilizing a scanning Michelson laser interferometer. A novel detection scheme for our interferometer is discovered, enabling imaging of the in-plane vibrations in addition to the out-of-plane component of the vibrations. We are able to measure the in- and out-of-plane oscillations of the silicon resonator at the resonance frequencies of the square-extensional and Lame´ modes. The measured results are compared with FEM simulations. In addition, undesirable parasitic vibrations in the electrode regions are observed.