Measuring Thermal Properties of Thin Film Materials Using Time Domain Thermoreflectance
Mohammed Abdelaziz, Vassar College ’16, Molly James, Vassar College ’17, Sushant Mahat, Vassar College ’16, Lauren Delgado, Vassar College ’19 and Prof. Brian DalyModern computing devices make heavy use of microprocessors which are manufactured using very thin films of metals, semiconductors, and insulators. Studying the thermal properties of these thin films can aid in determining the characteristics of useful films and their constituents, which will help develop novel films that can be used to build smaller and faster microprocessors. Apart from that, studying these properties for various materials also provides insight into physical principles that are not fully understood: how thermal conductivity in thin film materials differs from that in bulk material, and how the makeup of thin films affects their thermal conductivity. This experiment focused on determining the thermal properties of several thin film test samples provided by the Intel Corp. using the time domain thermoreflectance technique. In this technique, one set of infrared laser pulses from an ultrafast laser, the pump pulses, are used to heat the samples up and their cooling rate is determined by measuring the change in reflectivity over time of the samples. This change was quantified by reflecting a second set of laser pulses, the probe pulses, off the sample. The data gathered were compared against computer simulated cooling curves to determine the thermal conductivity of the samples.