DC and AC electrothermal charicterization of heated microcantilevers using scanning thermoreflectance microscopy

We report the application of scanning thermoreflectance microscopy for steady - as well as periodic-temperature calibration of a microheater-integrated atomic force microscope cantilever (or heated microcantilever). While the heated microcantilever was operated with either DC or AC powers, local thermoreflectance signals were measured using a home-built scanning thermoreflectance microscope and converted into local temperatures using a calibration with Raman thermometry. For our scanning thermoreflectance microscopy, temporal resolution of 10 μs and spatial resolution of 2 μm were achieved. The shrinkage of the AC temperature oscillation amplitude was observed as the modulation frequency increased and thermal cut-off frequency near 1 kHz was found. In addition, strong thickness-dependent thermoreflectance signals were experimentally confirmed and might be useful for noncontact thickness measurements of free standing microelectromechanical systems devices having uniform temperatures.