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Instrumentation

Thermoreflectance Thermal Property Measurements

Thermoreflectance (TR) laser-based measurement techniques can measure the thermal properties of substrates, thin films, multilayer structures, and their interfaces. TR uses modulated laser heating and thermal models to probe thermal properties by relating a material’s change in temperature to the resulting change in optical reflectance (coefficient of TR):

Non-contact and non-destructive
Measures in situ thin film, embedded, and multilayer materials
Large property range: ≈ 0.1 W/mK to ≈ 2400 W/mK
Can simultaneously fit for in-plane and cross-plane thermal conductivity
Simultaneously probe at variable depths (≈ 10's of nm to ≈ 10's of micron)
Spatially resolved measurements: 2D property mapping

Although TR is a powerful technique, there are some challenges to wider adoption: traditionally, TR instruments are custom built, requiring experienced staff to design, operate, and maintain; the data fitting and uncertainty analysis can be complex; and finally, validation standards and improved protocols are needed. Leveraging our existing expertise and collaborations with instrument vendors and the semiconductor industry, we have built a suite of TR metrology tools to evaluate, improve, and refine TR thermal property measurement methods, protocols, and instrumentation. Together, these tools enable us to:

Provide on-demand, impartial, and reliable thermal property measurements for industry and CHIPS projects
Support commercialization by working with existing vendors to customize and develop new thermal measurement instrumentation and techniques
Provide Independent Verification & Validation measurements for critical Interagency Programs

Instruments

TR can be categorized as Frequency Domain Thermoreflectance (FDTR), Steady State Thermoreflectance (SSTR), or Time Domain Thermoreflectance (TDTR). These techniques leverage sensitivity to different thermal properties and materials based on their characteristic thermal excitations and corresponding responses.