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Patricia Al-Alam1 Dheeraj Pratap1 Jaona Randrianalisoa1 Nathalie Trannoy1

1, University of Reims Champagne-Ardenne, Reims, , France

Scanning thermal microscopy (SThM) based on Atomic Force Microscopy (AFM) technique is used in order to investigate thermal properties of materials and mechanism of heat transfer at micro-and /or nanoscale [1-2]. Generally, in all SThM, a temperature sensor (thermocouple, thermoresistive …) is integrated into the probe which can measure simultaneously local temperature or generate local heating. A topographic and thermal image of materials with sub-micrometer spatial resolution can be obtained with this technique. Although various types of SThM probes have been developed so far, the probe selection is of great need. The present study deals with Wollaston resistive probe. The aim is to study the influence of sample structure on the thermal signal of Wollaston probe, to characterize and estimate the effect of probe volume on the thermal conductivity measurements. For that, a buried nanostructure sample is considered. The sample is composed of buried silicon steps under polished CVD SiO2. We develop a well-defined heat transfer numerical model of the probe-sample system for a better interpretation of experimental results obtained by SThM. Numerical simulations were performed using COMSOL Multiphysics which is based on finite element method. A 3D realistic geometry of the Wollaston probe is modelled in contact operation mode in order to obtain probe temperature behavior. The numerical model of probe/sample allows evaluating the flux dissipated by the platinum-rhodium wire and into the sample. The heat flux gives access to the thermal behavior of the probe in contact with the nanostructured sample. This work shows that the thermal signal is sensitive to the internal structures. The thermal signal gives access to a local thermal conductance that corresponds to a probed volume. We present and discuss our latest results.
The research leading to these results has received funding from the European Union Seventh Framework (EU FP7) Program FP7-NMP-2013-LARGE-7 (project QUANTIHEAT) under grant Agreement 604868, and from the Champagne-Ardenne Region A2101-03-Excellence.

REFERENCES
Majumdar, Lai, Chandrachood, Nakabeppu, Wu and Shi, Thermal imaging by atomic force microscopy using thermocouple cantilever probes, 1995
F.A. Guo, N. Trannoy, J. Lu, Analysis of thermal properties by scanning thermal microscopy in nanocrystallized iron surface induced by ultrasonic shot peening, Materials Science and Engineering: A, 2004.

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