International exchange award: Investigating effective scaling of Si-quantum and cryogenic-CMOS technologies at SemiQon

Kristopher Barr outside the VTT centre

Kristopher Barr a Research Associate at Strathclyde University was awarded an M4QN international exchange award to visit Janne Lehtinen, Chief Science Officer at SemiQon in Finland. The visit took place from 11th-30th March 2025.

Investigating effective scaling of Si-quantum and cryogenic-CMOS technologies at SemiQon

During the visit there was ample opportunity to understand all aspects for large scale manufacture of Si-quantum chips.  The exchange allowed observation of the entire process: – from device design, to back-/front-end fabrication, and the measurement team, where testing, validation and research occurs.

Kristopher writes “During my time with the design team, I was able to focus on development of a 2×2 Si-quantum dot design, with additional charge sensing dots. It was clear how SemiQon are utilizing their leading cryogenic-CMOS multiplexing technology alongside spin qubit designs. This combination challenges the open problem of scalability head on. It is set to enable significant scaling of SemiQons spin qubit architectures. I toured Micronova cleanroom facilities and shadowed the fabrication engineers, gaining understanding of the complex process of the back- and front-end processes of SemiQon wafers. This was possibly the most foundational experience. It has given deep insight into the critical aspects that allow competitive design of spin qubit devices. A design should be optimized based on fabrication strengths and capabilities.
Finally, I spent time with the measurement team, where I am most at home. Discussions with the measurement engineers allowed alignment of SemiQons goals and understanding of their streamlined setup. As a result of the exchange, I will put forward a device design for a future fabrication run. I have gained critical information for upcoming experiments at SEQUEL with SemiQon devices. I look forward to collaborating with SemiQon more in future.”

Benefits to the UK materials and quantum community

Scaling quantum systems operating in extreme cryogenic environments has proven difficult when transmitting information between the quantum-classical interface. The visit has helped identify the clear impact low-dissipation, cryo-CMOS technologies will have for development of large-scale quantum computing systems.

The visit helped to promote international knowledge transfer, and has also allowed for cross-sector collaboration. The trip highlighted the importance of commercializing academic research to benefit wider communities. During, and since, the visit there have been useful exchanges relating to experimental methods and techniques. The relationships formed have been positive and it has helped pave the way for future academic-industrial collaboration.

Kristopher writes “the UK government have released national semiconductor and quantum technologies strategies. These aim to foster diverse ecosystems to aid in world leading R&D, internation collaboration, commercialization, and the creation and protection of supply chains. Through the international exchange award, M4QN have demonstrated and assisted in facilitating the development of these rich communities.”

Visit Outcomes

The visit gave Kristopher skills and knowledge that he is already able to incorporate into his research. During the visit he was able to begin designing gate-defined Si-quantum dots compatible with SemiQon fabrication processes. A design will be put forward for an upcoming fabrication run.

The SEQUEL group at Strathclyde are finalizing the experimental setup with gate reflectometry to be conducted using SemiQon devices. Future collaboration and joint publication should result from this.