SURFACE INVESTIGATIONS BY SCANNING THERMAL MICROSCOPY

A scanning thermal microscope has been developed which is capable of i maging thermal properties of materials with high spatial resolution, F irst results indicate a lateral resolution less than 200 nm. The micro scope employs a miniaturized thermal probe whose rip is formed as a th ermocouple. The probe is laser heated to generate a thermovoltage. A s ample approaching the heated tip leads to a heatflow from the tip to t he cooler sample surface and thus to a decrease of the measured voltag e. In the initial experiments we scanned the tip above the sample surf ace with open feedback loop and mapped the thermovoltage at each locat ion of the scan range. Furthermore, we closed the feedback loop keepin g the thermovoltage constant and measured the z displacement of the pi ezoelectric tube carrying the probe. All these measurements yield topo graphical as well as thermal information of the sample surface. (C) 19 95 American Vacuum Society.