Microcantilever hotplates with temperature-compensated piezoresistive strain sensors

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 〈1 1 0〉 crystal direction where the piezoresistive coefficient is maximized and the other one was aligned to the 〈1 0 0〉 crystal direction where the piezoresistive coefficient is nearly zero. The fabricated devices exhibit excellent temperature compensation, with a 20× reduction in temperature sensitivity. The deflection sensitivity shifted only 10% for heating to 200 °C and cantilever deflection ∼10 μm. This work enables cantilever strain sensors that could measure temperature-dependant phenomena.