Thermoreflectance Imaging: What Is It?

Introduction

Thermoreflectance is the change in reflected light due to a change in temperature. Thermoreflectance is not based on IR emission to obtain a thermal image. We can probe a device with visible light and measure the change in reflected intensity with high spatial and temporal resolution.
Thermoreflectance is the change in reflected light due to a change in temperature. Thermoreflectance is not based on IR emission to obtain a thermal image. We can probe a device with visible light and measure the change in reflected intensity with high spatial and temporal resolution.

Thermoreflectance thermal imaging is dependent on the measurement of the relative change in the sample’s surface reflectivity as a function of temperature. As the temperature of the sample changes, the refractive index, and therefore, the reflectivity also changes. The change in reflectivity is dependent on the Thermoreflectance Coefficient, a basic material property that is a function of the illumination wavelength, the sample material and material surface characteristics, and the ambient temperature.

With illumination wavelengths in the visible range, a lock-in technique to enhance signal to noise ratio, and advanced embedded algorithms for data analysis the Microsanj thermal imaging systems surpass traditional thermal imaging techniques achieving:

  • Spatial resolution less than 300 nanometers
  • Transient resolution less than 1 nanosecond
  • Temperature resolution to 0.25 ⁰C

For further information see: AN-003, “Understanding the Thermoreflectance Coefficient: The Key to Achieving Optimal Temperature & Spatial Resolution for Thermal Imaging of Microelectronic Devices”
http://www.microsanj.com/application-notes/understanding-thermoreflectance-coefficient

For a comparison to traditional imaging techniques see: AN-004 “Comparing Thermal Imaging Approaches” http://www.microsanj.com/application-notes/comparing-thermal-imaging-approaches

Microsanj is a leading supplier of thermal imaging systems based on the Thermoreflectance principal. Shrinking device dimensions and complex 3-dimensional architectures have greatly exacerbated the ability to thermally analyze today’s state-of-the-art microelectronic and optoelectronic devices, information critical for ensuring device performance and long term reliability. Microsanj has carefully engineered and configured their systems to be cost-effective solutions with the attributes and resolution necessary to meet the thermal imaging challenges of these advanced devices.