SCANNING THERMAL IMAGING MICROSCOPY USING COMPOSITE CANTILEVER PROBES

We have developed a simple technique of measuring surface temperature contrast with submicron spatial resolution. The technique uses the atomic force microscope (AFM) to scan a composite cantilever probe made of a thin metal film (aluminum or gold) deposited on a regular silicon nitride AFM probe. During tip-surface contact, heat flow through the tip changes the cantilever temperature which bends the cantilever due to differential thermal expansion of the two probe materials. An ac measurement is used to separate cantilever bending due to temperature and topography. To eliminate image distortion due to air heat conduction, thermal images of a biased resistor were obtained in vacuum (10-5 Torr). The images showed hot spots due to current crowding around voids in the heater and suggested a spatial resolution of 0.4 μm.© 1995 American Institute of Physics.