Public thesis defense Shiqi Ma - ICTEAM

Silicon and Porous Silicon Integrated Waveguide Technologies for Sub-Terahertz Applications

Wednesday November 25th, 2026 - 4:30pm - Auditorium BARB94 - Place Sainte-Barbe, 1 - 1348 Louvain-la-Neuve

The continued scaling of silicon technologies has extended active-circuit operation into the millimeter-wave and sub-terahertz frequency ranges, while interconnects and passive components remain constrained by propagation loss, parasitic modes, fabrication complexity, and packaging. This thesis investigates silicon-based transmission-line and waveguide technologies for integrated sub-terahertz systems, with emphasis on the trade-offs between RF performance, fabrication, integration, and functionality.

The work first establishes an experimental benchmark for planar transmission lines implemented on different silicon technologies and shows that their performance depends on the combined substrate, interface, conductor, and return-path implementation. While planar lines remain suitable for local interconnection and probe access, their accumulated loss limits longer propagation at sub-terahertz frequencies.

Two integrated waveguide platforms are then developed. A DRIE-based silicon-filled rectangular waveguide provides low-loss D-band propagation and high-quality resonators using a bonding-free fabrication approach. The concept is further investigated for post-processing and integration on a foundry CMOS die, highlighting the technological challenges associated with alignment and metallization.

A second platform based on selectively anodized porous silicon enables single-wafer waveguide fabrication without DRIE-defined sidewalls or wafer bonding. Experimental demonstrations include waveguides, resonators, a bandpass filter, and a dielectric sensor.

Together, these results establish complementary silicon-based approaches for sub-terahertz interconnects, passive components, and integrated sensing applications.

Jury members

Prof. Dimitri Lederer   (UCLouvain), Supervisor
Prof. Jean-Pierre Raskin (UCLouvain), Supervisor
Prof. Christophe De Vleeschouwer (UCLouvain), Chairperson
Prof. Laurent A. Francis  (UCLouvain), Secretary
Prof. Isabelle Huynen (UCLouvain)
Prof. Gaël Gautier (Université de Tours, France)
Dr.-Ing. Andreas Rennings (University of Duisburg-Essen, Germany)

Pay attention : the public defense of Shiqi Ma will also take place in the form of a videoconference