We had a highly informative conversation with two researchers from the University of Glasgow who have shared their innovative projects related to the fabrication of superconducting qubits. Dr Jharna Paul is a Research Associate and Valentino Seferai is a PhD student within the Quantum Circuits Group which is led by Professor Martin Weides.
Both researchers use the Oxford Instruments PlasmaPro® 100 Cobra ICP RIE system for the fabrication of superconducting qubits that take place at the state‑of‑the‑art James Watt Nanofabrication Centre (JWNC) cleanroom within the university.
Previously, Dr Jharna and Valentino have focused on the creation of integrated and highly coherent cavity magnon–polariton systems for quantum information processing. The research team has achieved “strong coupling on chip devices comprising a superconducting resonator and a YIG sample at sub-Kelvin temperatures”1.
For both researchers, meticulous process optimisation is fundamental. They usually develop their own recipes which requires deep understanding of the process. “We use Oxford Instruments PlasmaPro Cobra ICP etching system, as you can effectively control the plasma, the power, the gas delivery, the chamber pressure and the substrate temperature”, as Dr Jharna Paul states.
The research team investigates dry etch recipes that produce high coherence qubit devices to build the superconducting circuit. This device fabrication needs high selectivity and accurate control of the plasma. The goal is to etch the metals and other materials as cleanly as possible without leaving any residues and without damaging the metals in order to get a good etch profile. Oxford Instruments PlasmaPro 100 Cobra ICP provides application related flexibility with controlled high etch rates for deep features and low etch rates for shallow features with high precision and low damage.
1. Appl. Phys. Lett. 119, 033502 (2021); https://aip.scitation.org/doi/10.1063/5.0054837 22 April 2021. Accepted: 24 June 2021. Published Online: 19 July 2021
"Once you optimise the process, the PlasmaPro 100 Cobra ICP system is reliable with repeatable results".
Dr Jharna Paul, Research Associate, University of Glasgow
"The ICP system effectively controls the etch rate and makes the process more stable".
Valentino Seferai, PhD Student, University of Glasgow
With over 11 years of collaboration with University of Glasgow, we continue to support the innovative fabrication processes for power semiconductor, optoelectronic, quantum and many more devices.
For device fabrication, the University of Glasgow uses various plasma systems, including PlasmaPro 100 RIE and FlexAL ALD system. Oxford Instruments is an intrinsic part of the quantum community and to enable the quantum devices to be characterised at millikelvin temperatures, in January 2021, the university announced the purchase of Oxford Instruments’ next generation Cryofree® refrigerator, Proteox.Read the full Case Study
James Watt Nanofabrication Centre in the University of Glasgow