Dr Magdalena Ulmeanu is an Applications Engineer at Oxford Instruments Plasma Technology. Her work covers the field of plasma etching processes with a focus on Cryogenic Silicon Etching and Mixed Gas Silicon Etching.

Title: Fabrication and Nanoscale Characterisation of Sidewall Roughness in SOI Waveguides
Date: TBC

The poster presentation at MNE 2025 demonstrates a robust plasma etch developed process for nanoscale fabrication of silicon-on-insulator (SOI) waveguides. The high surface quality of the sidewall roughness was evaluated using an Oxford Instruments Atomic Force Microscope (AFM), establishing a reliable baseline for evaluating process-induced sidewall variations. This will offer critical feedback for further process refinement and modelling of optical losses in high-confinement SOI waveguides.

Arjun Moothedath is an Application Engineer (Etch) at Oxford Instruments Plasma Technology, UK. With a background in Electronics and Communication Engineering, he specialises in silicon-based process development. Currently, his main focus is on developing the Bosch silicon etching process using the PlasmaPro 100 Estrelas Deep Reactive Ion Etch (DRIE) tools.

Title: Post-etch Surface Modification for Sidewall Smoothing in Deep Reactive Ion Etched Silicon
Date: TBC

The poster presentation at MNE 2025 demonstrates a post-etch surface modification approach based on fluorine chemistry to smooth the sidewalls created by DRIE. The technique effectively removed scallops at the top of the vias and reduced scallop depth by approximately one-third in the middle and lower sections, resulting in average depth of 23 nm and 14 nm, respectively. We have implemented this smoothing process into the fabrication of niobium nitride superconducting TSVs, achieving a superconducting transition temperature of 10.7 K. These enhanced TSVs are well-suited for superconducting systems, particularly those operating at millikelvin temperatures, such as qubit shielding and signaling in superconducting qubit computing.