/Gigahertz Ultrasound Microscopy for 3D Semiconductor Technologies

Gigahertz Ultrasound Microscopy for 3D Semiconductor Technologies

PhD - Leuven | Just now

This PhD project offers a unique opportunity to redefine the future of semiconductor inspection by advancing Gigahertz Ultrasound Microscopy (GUM).

As the semiconductor industry pushes the boundaries of Moore’s Law, the need for ultra-precise, non-destructive metrology becomes more urgent than ever. Shrinking feature sizes, complex 3D architectures, and the rise of hybrid bonding demand inspection tools that can see deeper, sharper, and faster — without damaging the device.

 

This PhD project offers a unique opportunity to redefine the future of semiconductor inspection by advancing Gigahertz Ultrasound Microscopy (GUM) — a cutting-edge technique that uses ultra-high-frequency sound waves to image materials at sub-micron and even nanometer scales.

 

Traditional metrology tools like optical microscopy and AFM are hitting their limits. GUM, on the other hand, offers the ability to probe sub-surface features with nanometer-level precision, overcoming some of the limitations of optical diffraction and providing deeper penetration into semiconductor materials. Its acoustic nature allows it to map mechanical properties like elasticity, density, and layer thickness, providing crucial insights into the structural integrity and quality of semiconductor devices at the nanoscale. Today, its low-frequency counterpart, i.e. Scanning Acoustic Microscopy (SAM), has become the reference technique for void detection and hence turned into a critical inspection technique for 3D integration and bonding applications. However, its detection limit is being challenged as the hybrid bond pitch scales down. We foresee GUM to become an indispensable tool for ensuring reliable production in future semiconductor technologies as sub-µm voids turn into killer defects in bonded wafer pairs — but current systems are too slow and limited for industrial deployment.

 

This project aims to break through those barriers by:

  • Developing compact, high-frequency acoustic scan heads using integrated leaky ultrasound resonators.
  • Enabling massively parallel GHz imaging to overcome throughput limitations.
  • Innovating new methods to enhance signal generation, detection, and image reconstruction.
  • Tackling real-world challenges like signal-to-noise ratio, resolution scaling, and sample interaction.

 

What you’ll gain

  • Work at the forefront of nano-acoustic imaging, with direct relevance to the semiconductor industry.
  • Collaborate with leading experts in metrology, materials science, and device fabrication.
  • Access to state-of-the-art cleanroom and acoustic microscopy facilities.
  • Contribute to next-generation inspection tools that could become standard in advanced IC fabs.
  • Publish in high-impact journals and present at top-tier conferences.

Required background: Engeering Technology, Engineering Science

Type of work: 10% literature, 40% modeling+design, 50% characterization

Supervisor: Xavier Rottenberg

Co-supervisor: Claudia Fleischmann

Daily advisor: Grim Keulemans

The reference code for this position is 2026-144. Mention this reference code on your application form.

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