High Resolution, Real-Time Flatness and Thermal Expansion Metrology

Schematic of surface curvature measurement and thermal expansion measurement apparatus

Invention Summary:

During manufacturing of thin films and semiconductors, it is critical to monitor the flatness and thermal expansion of samples to identify and manage stresses. These parameters are currently measured optically based on the deflection of multiple parallel beams, but, this approach is limited in the sample size, resolution, and the distance between the sample and the measurement apparatus.

Researchers at Rutgers have developed a novel metrological apparatus to overcome these limitations. Specifically, a wide beam is directed at the sample, and the deflected beam passes through a mask. The surface curvature (flatness) is determined from the resulting interference pattern. This approach enables high-resolution flatness measurements of small samples and mapping of large samples. It is also possible to measure surfaces with complex underlayers or surface features. Furthermore, the measurement apparatus can be separated from the sample, enabling measurement at high temperatures or during other treatments and monitoring of stress and thermal expansion in situ.

As components become smaller, it is essential to use a sensitive apparatus with the power to identify stress induced failures in these reduced size components.

Market Applications:

Quality control:

  • Semiconductor manufacturing
  • Thin film fabrication
  • Lens manufacturing
  • Packaged structures


  • High resolution (4x10-6 δ)
  • Measure large radius of curvature (< 1000m) of a small sample area (4x4 mm2)
  • Simple setup, tolerant to vibrations
  • Measurement of small samples
  • Mapping of large samples
  • Robust measurement of complex surfaces with underlayers and surface features
  • Measurement at high temperature (1500 °C) or during other sample treatment
  • In-situ thermal expansion measurement

Intellectual Property & Development Status:

Patent pending. Available for licensing and/or research collaboration

Patent Information:
For Information, Contact:
Shu Wang
Licensing Manager
Rutgers University
Machines & Instruments