Revealing the Unseen With Thermoreflectance

April 12, 2024by Ron Fisher

Harnessing thermoreflectance for comprehensive semiconductor testing

In the field of semiconductor electronics, thermal metrology has become increasingly problematic. Conventional measurement methods often fail to produce accurate, repeatable results, especially for thin films and other materials at the nanoscale. That’s why the thermal metrologists, physicists, and material scientists at Laser Thermal moved away from conventional approaches that rely on measurements of reflected light and instead turned to steady-state thermoreflectance (SSTR). 

Using advanced detection schemes and signal processing to monitor minute changes in reflectivity due to small temperature changes, this method provides the accuracy, speed, and ability to measure down to the nanoscale that conventional methods lack. The sensitivity at these scales enables SSTR to probe the thermal behavior of materials at device scales, providing insights into their thermal conductivity and performance characteristics.

Benefits of Steady-state Thermoreflectance

Efficient thermal management is necessary in electronics manufacturing to ensure device reliability and longevity. Thin film materials, such as dielectrics, metals, thermal interface materials and heat spreaders, play a crucial role in dissipating and diverting heat generated by electronic components. SSTR is a valuable tool for characterizing the thermal conductivity and heat dissipation capabilities of these materials, enabling designers to optimize thermal management solutions and enhance device performance.

Let’s explore a few of the benefits that SSTR offers for semiconductor research and development.

Accurate Measurement of Thermal Signatures

Central to the power of steady-state thermoreflectance is its ability to measure the unique thermal signatures exhibited by different materials. These signatures, influenced by factors such as: 

  • composition
  • density
  • thickness
  • number and quality of interfaces
  • defect concentration

serve as critical indicators in semiconductor and microelectronics testing. Small changes in thermal signatures can be correlated to changes in these various properties. Through precise measurement and analysis of small reflectivity changes, steady-state thermoreflectance facilitates accurate characterization and quality control, empowering researchers and engineers to optimize device performance and reliability.

Anomaly Detection

Another distinguishing feature of SSTR is its ability to illuminate sub-surface imperfections and anomalies within materials. Unlike conventional imaging techniques, SSTR can detect otherwise imperceptible cracks, defects, and variations in thermal conductivity. This added capability enables game-changing high-throughput quality assessments, understanding of the nature and quality of bonding layers, and defect detection.

While traditional methods capture surface-level features, SSTR’s ability to capture insights beyond the surface is especially useful for semiconductor testing, where understanding the thermal behavior of materials at various depths is crucial for optimizing device performance and reliability. By delving beneath the surface, steady state thermoreflectance equips researchers and engineers with a comprehensive understanding of material properties, facilitating informed decision-making and innovation.

Understanding Thermal Properties of Thin Films

Thin films, consisting of layers of material with nanometer to micrometer thickness, are ubiquitous in industrial applications, playing a crucial role in the performance and reliability of semiconductors. SSTR offers a non-destructive and highly sensitive method for probing the thermal properties of thin films, allowing researchers and engineers to assess their uniformity, thickness, and thermal properties to produce devices with enhanced performance and reliability.  The added benefit of capturing the thermal boundary resistance between materials when measuring with SSTR allows for a more accurate characterization of the thermal resistances at play in as fabricated device geometries.

SSTR represents a paradigm shift in imaging technologies, offering a comprehensive and insightful approach to semiconductor R&D and beyond. It plays a pivotal role in the characterization, evaluation, and optimization of thin films across a wide range of industries and applications. From quality control in manufacturing processes to thermal management in electronics and the development of advanced optoelectronic devices, SSTR offers invaluable insights into the thermal properties of thin films, driving innovation and progress in materials science and engineering. 

If you would like to learn how SSTR could revolutionize your thermal metrology needs, set up a free consultation or watch our explainer video.