Array of Microcantilever Heaters with Integrated Piezoresistors

This paper presents improved design, fabrication, and characterization of a small array of silicon microcantilever heaters with integrated piezoresistors. The fabricated microcantilever arrays are made from single crystal silicon with selective doping such that parasitic bending and electromigration can be suppressed during high temperature operation. Detailed characterization was performed to test the device electrical, thermal, and mechanical properties. The performance and crosstalk between heater and piezoresistor elements was thoroughly tested. The resistive heater can reach temperature higher than 600°C, and its temperature coefficient of electrical resistance was 2.01 × 10
^-3
Ω/Ω-°C. When biased at 2 V in a Wheatstone bridge, the deflection sensitivity of the piezoresistor was 4.25 × 10
^-4
V/V-μm and remarkably, the heater circuit had a non-negligible deflection sensitivity of 7.86 × 10
^-5
V/V-μm. Both the piezoresistor and the resistive heater were interfaced with a commercial atomic force microscope (AFM) to measure their sensitivities during topography sensing of a calibration grating. As expected, the sensitivity of thermal reading was at least one order of magnitude greater than that of piezoresistive reading.