Field-effect piezoresistors for vibration detection of nanobeams by using monolithically integrated MOS capacitors

    Authors

    H. T. Cheng; H. Yang; X. X. Li;Y. L. Wang

    Comments

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    Abbreviated Journal Title

    J. Micromech. Microeng.

    Keywords

    NANOMECHANICAL RESONATOR; ETCH-STOP; DISPLACEMENT; CANTILEVERS; QUANTUM; MOTION; Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Instruments & Instrumentation; Materials Science, Multidisciplinary; Mechanics

    Abstract

    A novel piezoresistive sensing method is presented herein for the detection of nanobeam resonator based on a monolithically integrated MOS (metal-oxide-semiconductor) capacitor structure. The bottom layer of the nanobeam located beneath the MOS capacitor is utilized as a piezoresistor for the detection of internal stress resulting from nanobeam deformation, and therefore the challenging process of ultra-shallow junction doping is avoided. When a bias voltage applied on the MOS gate exceeds the threshold, the depletion layer width is built up to the maximum, and the piezoresistive cancellation effect beside the neutral plane is eliminated. Based on a conventional microelectromechanical (MEMS) process, an MOS capacitor is fabricated at the terminal of a double-clamped nanobeam with dimensions of 46 mu m x 7 mu m x 149 nm. The measured R-V curve of this MOS structure presents a 64.7 nm thick piezoresistor which closely agrees with the design. This double-clamped nanobeam is excited into mechanical resonance by mounting it on a piezoelectric ceramic, and the amplitude-frequency response is measured by a network analyzer. The measured resonant frequency is 3.97 MHz and the quality (Q)-factor is 82 in atmosphere environment. Besides, this piezoresistive sensing method is verified by a laser-Doppler vibrometry.

    Journal Title

    Journal of Micromechanics and Microengineering

    Volume

    23

    Issue/Number

    2

    Publication Date

    1-1-2013

    Document Type

    Article

    Language

    English

    First Page

    8

    WOS Identifier

    WOS:000313752800011

    ISSN

    0960-1317

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