Microcantilever hotplates with temperature-compensated piezoresistive strain sensors

Abstract

This paper describes the design, fabrication, and characterization of microcantilever hotplates having both a resistive heater and temperature-compensated piezoresistive strain gauges. The heater was defined near the cantilever free end and the piezoresistive strain gauges were integrated near the clamped base. To realize temperature compensation, a pair of identical piezoresistors was defined in close proximity. One piezoresistor was aligned to the (110) crystal direction where the piezoresistive coefficient is maximized and the other one was aligned to the (100) crystal direction where the piezoresistive coefficient is nearly zero. The fabricated devices exhibit excellent temperature compensation, with a 20x reduction in temperature sensitivity. The deflection sensitivity shifted only 10% for heating to 200 degrees C and cantilever deflection similar to 10 mu m. This work enables cantilever strain sensors that could measure temperature-dependant phenomena. (c) 2007 Elsevier B.V. All rights reserved.