WSI: On-Wafer Sub-THz Measurements from Fundamentals to Next-Generation Tools and Applications

Presentation Abstract
With the operating frequencies of 6G wireless communications and next-generation automotive radars extending above 110GHz, accurate and robust on-wafer measurements are essential for enabling design, model verification, and industrialization. While a solid foundation has been established over the past decades in calibration methodologies and measurement platforms, many challenges remain as research and development move deeper into the sub-THz domain. As advanced devices, circuits, interposers/packaging technologies emerge alongside high-frequency systems, new measurement scenarios and calibration requirements continue to arise. At the same time, new methodologies such as AI-driven automation, advanced calibration algorithms, and novel calibration substrates are being developed to address these evolving needs. This full-day workshop brings together international experts from national metrology institutes, academia, and industry to address these challenges from complementary perspectives. The program begins with a focus on the fundamentals of calibration and measurement, reviewing the state-of-the-art in instrumentation, calibration techniques, and traceability at mm-wave frequencies, followed by comprehensive design guidance for calibration standards and systematic analysis of probe-induced uncertainties. These sessions lay the foundation for reliable and reproducible on-wafer measurements at sub-THz frequencies, offering both the theoretical framework and practical guidance needed for advancing calibration practices. The workshop then transitions to next-generation tools and methodologies that are extending the state-of-the-art. Topics include AI-driven nano-robotic probe stations that achieve sub-micron alignment and reproducible probe placement, calibration algorithms that go beyond conventional error models to capture mode conversion and crosstalk, and the development of GaAs impedance standard substrates supporting diverse calibration standards and measurement scenarios. Recent advances in broadband vector network analyzer technology will also be presented, including single-sweep measurements up to 250GHz and new calibration capabilities. These contributions demonstrate how innovative approaches are being translated into practical platforms, enhancing both robustness and scalability. Finally, the workshop highlights applications and industrial implementations. Talks will show how advanced calibration and measurement techniques are applied in wafer-scale silicon interposer technologies — addressing stackup choices, GSG pad design, and multimode suppression — as well as in high-volume silicon device testing for next-generation components. Presentations from industrial experts will emphasize optimizing calibration substrates, comparing methodologies such as modal versus SOLR calibration, and reducing measurement uncertainties under real manufacturing constraints. Together, these examples illustrate how academic innovation and industrial practice are converging to enable accurate and traceable measurements at scale. By covering the full spectrum from fundamentals to industrialization, this workshop offers participants both foundational insights and exposure to cutting-edge solutions. The day will conclude with an open discussion, providing a forum to exchange ideas, identify open challenges, and shape the roadmap for accurate, scalable, and robust on-wafer sub-THz measurements.