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Page d'accueil Archives Thermal Letter Responsables Réunions à venir Assembly for International Heat Transfer Conferences
International Heat Transfer Conference 12
2002, 18-23 August, Grenoble, France

Development of Scanning Thermal Microscopy for Nano-scale Real Temperature Measurement

Get access DOI: 10.1615/IHTC12.3950
6 pages


Scanning Thermal Microscopy (SThM) takes a thermal image by scanning a cantilever probe with a tiny thermal sensor over sample surface. Spatial resolution of thermal measurement has been improved by reducing sensor size, and reached to less than 30nm. However, an important issue remains: quantitative temperature measurement. It is difficult to convert measured values to temperature or properties because conventional SThM essentially measures not temperature, but heat flow rate between the sample and the cantilever; this depends on both temperature and a contact thermal conductance influenced by such factors as thermal properties, sample surface shape, adsorption layer, contact force, and so on. Therefore, we propose an active temperature measurement method using a thermal feedback system. In the active method, feedback control maintains equality of the cantilever temperature and the sample by detecting heat flow along the cantilever and feeding power proportional to it to the cantilever; then, cantilever temperature is measured by another sensor. This active method can measure real temperature in principle as long as conductance has finite value, no matter how it changes. We have experimentally examined the active method by producing and modifying multi-function cantilevers with a micro-fabrication technique. The first micro-fabricated cantilever with a differential thermocouple as a heat flow sensor had insufficient sensitivity for measuring real temperature under low contact conductance conditions. In contrast, a modified cantilever with a thermopile demonstrated good performance in real temperature measurement regardless of difference in sample thermal conductivity. Furthermore, imaging tests demonstrated that the active method can take a temperature image by compensating the influence of change in the contact condition based on sample properties and shape.
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