Session: 11-45-01: Technique development for thermophysical characterization

Paper Number: 119973

119973 - Measurement of Thermomechanical Response to Periodic Heating in Semiconductors and Dielectrics 

Thermoreflectance techniques have gained widespread use for thermophysical property characterization for both thin films and bulk materials. The typical implementation of both time and frequency domain techniques this technique is a two laser pump-probe setup which is traditionally used to measure thermal properties in radially symmetric samples. A metal transducer layer often is patterned onto a sample for increased sensitivity. The transducer layer converts incident light from the pump laser into heat, which diffuses into the sample. Thermoreflectance techniques measures changes in reflected signal, which are proportional to the temperature rise on the surface of the sample in response to the heating from the pump beam. In the frequency domain implimentation the phase difference between the of the reflected signal and pump beam is related to thermal properties through an analytical heat transfer model.

This talk describes a novel three laser thermoreflectance characterization setup measuring both thermal and mechanical response to periodic heating. This system is referred to as T-MeHR (Thermo-Mechanical Heating Response). The thermal response is measured using changes in reflectance of the sample surface as measured by a probe beam, similar to frequency domain thermoreflectance. The mechanical response is measured using a 1550 nm laser to measure interferometric response and infer surface displacement. Several different measurement types are examined: (1) measurement of bulk materials (2) depth resolution for interfaces, and (3) lateral resolution of buried features. It is additionally shown that thermoreflectance contributions of the interferometric signal can be accounted for.

Thermal and mechanical response to bulk materials, thin films, and bonded samples are predicted using finite element analysis (FEA) models. T-MeHR experiments are compared to these multiphysics models. These models are used to analyze data as well as assess uncertainty in fitted parameter values. The FEA model is additionally used to predict thermal characterization problems which may be aided by interferometric data. Particular attention is given to cases where interferometric data shows greater sensitivity then the thermoreflectance data and boundary conditions of the mechanical model.

The three beam T-MeHR technique demonstrates how sub-surface characterization problems may become substantially easier when Multiphysics measurements to periodic heating are taken. This system provides a new direction for thermophysical property characterization as well as defect identification.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525

Presenting Author: Wyatt Hodges Sandia National Laborotories

Presenting Author Biography: Wyatt Hodges is Senior Member of Technical Staff at Sandia National Laboratory, working in the Thermal Science and Engineering group on a variety of modeling and experimental efforts. His current and past projects include subsurface thermal property extraction, thermal analysis in mechanical testing, battery failure prediction, and electrothermal sensing techniques for biomedical applications. Wyatt completed his PhD in mechanical engineering at University of California, Berkeley, and studied macro- and microscale heat transfer.

Authors:

Wyatt Hodges Sandia National Laborotories
Amun Jarzembski Sandia National Laborotories
Ben Treweek Sandia National Laborotories
Brenden Herkenhoff Sandia National Laborotories
Greg Pickrell Sandia National Laborotories