Session: 10-01 Interactive Presentations

Paper Number: 97327

97327 - A Magnitude Modulated Thermoreflectance Technique for Measurements of Thermal Resistance and Heat Capacity of Thin Films and Bulk Materials 

Measuring the thermal resistances associated with thin films is critical for materials research within the semiconductor industry, however traditional measurement techniques such as Time or Frequency Domain Thermoreflectance (TDTR and FDTR respectively) come with complications limiting their widespread adoption.

In these traditional thermoreflectance techniques, two laser beams serve to heat the sample (pump), and subsequently monitor changes in reflectivity (probe), which corresponds to changes in temperature.

We combine the principles behind SSTR (where the magnitude of the temperature response is roughly proportional to the net resistance), with that of FDTR (where the frequency-dependent response of the material system depends on all thermal properties). By examining the magnitude of the reflectivity response at multiple frequencies, we may now simultaneously measure multiple thermal parameters, such as thermal conductivity, volumetric heat capacity or thermal boundary conductance. This also enablesthe tightening of uncertainty of measured parameters.

To validate this approach, we measure a variety of thin ALD and MBE -grown films (2-100nm) on several substrates (sapphire, silicon, diamond). All samples have an 80nm aluminum transducer deposited on top, and we measure the net thermal resistance across the film, in addition to the thermal conductivity of the substrate itself. We also measure bulk substrates, demonstrating the simultaneous measurement of thermal conductivity and heat capacity. We include robust uncertainty analysis to establish upper and lower bounds of measured values, and validate these results with an in-house TDTR system.

Presenting Author: Thomas Pfeifer University of Virginia