ERRORS ASSOCIATED WITH THE DESIGN, CALIBRATION AND APPLICATION OF PIEZORESISTIVE STRESS SENSORS IN SILICON(100)

Successful application of piezoresistive sensors for stress measurement requires both properly designed sensors and accurately calibrated values of the piezoresistive coefficients as well as a knowledge of potential sources of error that may be encountered during sensor application. In this work, results of analyses of errors associated with the design, calibration and application of piezoresistive stress sensors fabricated on (100) silicon are presented. In particular, sensor rotational alignment errors during fabrication and resistance measurements errors during calibration have strong effects on the values of the piezoresistive coefficients that are extracted from the calibration process. Also, calibration errors induced by mismatches in the resistor values and/or the actual piezoresistive coefficients of the various resitors in a sensor rosette have been quantified, and the importance of using data acquired only from well-matched resistor rosettes is demonstrated. Finally, it is shown that temperature measurement errors play a pivotal role in determining accuracy of the results obtained during calibration and application of these sensors.