Title

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

Authors

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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