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Proceedings Paper

Reduction of uncertainty in the measurement of the piezoresistive coefficients of silicon with a three-element rosette
Author(s): J. Fredrik Creemer; Patrick J. French
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Paper Abstract

The accuracy of piezoresistive based silicon sensors is partially determined by the uncertainty in the piezoresistive coefficients. In the production of sensors it is therefore desirable to measure the coefficients for the used technological process to avoid costly calibration of the sensors after production. A practical measurement method consists of bending a three-element rosette. The resulting resistance changes are used to calculate the independent piezoresistive coefficients (pi) 11, (pi) 12, and (pi) 44. A recognized problem of this method are the large uncertainties in the smallest calculated coefficients. These uncertainties arise partially from errors in the resistance measurements. This paper shows that the calculation of the coefficients is very sensitive to the measurement errors. This sensitivity is especially pronounced if there are large differences in magnitude between (pi) 11, (pi) 12, and (pi) 44, such as in p-type silicon. It appears, however, that the error sensitivity can be greatly reduced by optimizing the rosette orientation in the (001) crystal plane. For a p-type silicon rosette the optimum orientation is k*(pi) /2 (k equals 0, 1, 2,...) with respect to the [100] axis. Orientation along these angles may result in a reduction of the uncertainties up to a factor 48.

Paper Details

Date Published: 20 July 1998
PDF: 11 pages
Proc. SPIE 3328, Smart Structures and Materials 1998: Smart Electronics and MEMS, (20 July 1998); doi: 10.1117/12.320192
Show Author Affiliations
J. Fredrik Creemer, Delft Univ. of Technology (Netherlands)
Patrick J. French, Delft Univ. of Technology (Netherlands)

Published in SPIE Proceedings Vol. 3328:
Smart Structures and Materials 1998: Smart Electronics and MEMS
Vijay K. Varadan; Paul J. McWhorter; Richard A. Singer; Michael J. Vellekoop, Editor(s)

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