Piezoresistive cantilevers in a commercial CMOS technology for intermolecular force detection

We report the development of piezoresistive cantilevers for intermolecular force detection in biochemical sensing, by using a commercial CMOS technology. The detection of the small forces involved in molecular recognition requires cantilevers with a small spring constant and high force sensitivity. We have fabricated polycrystalline silicon cantilevers by using the two polysilicon layers of a commercial CMOS process with minimum design rule widths. The cantilevers have been released by post-process micromachining. The upper polysilicon layer has been used as a piezoresistor. CMOS amplifying circuits have been integrated on-chip with the cantilever structures. The cantilevers have small spring constants ranging from 1.5 to 12 mN/m. The complete system has been successfully tested by applying a known transverse displacement with an AFM tip. A force sensitivity of 8 mu V/pN and resolution of 50 pN has been obtained. This high resolution is obtained with CMOS polysilicon, which has a relatively low piezoresistive coefficient, but this is compensated by the integration of signal-processing circuitry.

Published in:
Electron, Ion and Photon Beam Technology and Nanofabrication (EIPBN), 83, 4-9, 1302-1305
Presented at:
Electron, Ion and Photon Beam Technology and Nanofabrication (EIPBN), Baltimore, USA, 2006
Invited Talk

 Record created 2013-08-06, last modified 2018-03-17

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