| AVS 56th International Symposium & Exhibition | |
| MEMS and NEMS | Friday Sessions |
| Session MN-FrM |
| Session: | Multi-scale Interactions of Materials and Fabrication at the Micro- and Nano-scale |
| Presenter: | J. Cross, Cornell University |
| Authors: | J. Cross, Cornell University B.R. Ilic, Cornell University M. Zalalutdinov, Global Strategies Group J. Baldwin, Naval Research Laboratory B. Houston, Naval Research Laboratory H. Craighead, Cornell University J.M. Parpia, Cornell University |
| Correspondent: | Click to Email |
We present an overview of studies on a piezoresistive transduction mechanism for detecting MEMS resonator motion. The transduction mechanism is based upon flexure of two fabricated stacked layers of polysilicon, separated by a thin dielectric material. We have used thermal silicon dioxide and LPCVD silicon nitride for dielectric layers. The dielectric material’s resistivity can be reproducibly electrically tuned via breakdown to tailor a vertically-oriented piezoresistive transducer between the polysilicon layers. The transduction mechanism is presented analytically, along with examples of non-linear data used to determine the displacement of the resonators. We obtain a gauge factor of approximately 5 with silicon dioxide as the dielectric, which is adequate for direct detection of the resonator motion without amplification or impedance matching. Integrated resonator-transducer devices in various geometries, such as double-clamped beams and cantilevers, have been fabricated using this method and we report on the effectiveness of various geometric parameters as well as various thicknesses and resistances of dielectric layers. As the film stack is composed entirely of CMOS compatible materials, we discuss a fabrication recipe for integrating this transduction mechanism with a conventional CMOS fabrication process. This work was partially supported by the Office of Naval Research, DARPA, and fabrication was performed at the Cornell NanoScale Science and Technology Facility.