Soitec’s 28Si FD-SOI Substrates Target 99.999% Fidelity for Quantum Processors

Quobly and Soitec have achieved a key milestone in quantum microelectronics with the integration of custom 28Si FD-SOI substrates into STMicroelectronics’ 300mm fabrication facility in Crolles, France. These substrates, manufactured by Soitec, are now cycling for technology and process development, aiming to unlock single-qubit gate fidelities approaching 99.999%. This collaboration establishes a fully integrated supply chain, from advanced materials to quantum integrated circuits, and represents a global first in the field of FD-SOI with a 28Si-enriched channel, accelerating the industrialization of silicon-based quantum processor units (QPUs).

28Si FD-SOI Substrates Enable Quantum Performance

Quobly is advancing industrialization with Soitec’s 28Si FD-SOI substrates now being tested in STMicroelectronics’ 300mm fabrication facility. These custom wafers are engineered to minimize isotopic impurities, significantly reducing quantum noise. This reduction is expected to unlock single-qubit gate fidelities approaching 99.999%, a critical step towards developing reliable and scalable silicon-based quantum processors. This milestone represents a global first for FD-SOI technology utilizing a 28Si-enriched channel.

These 28Si FD-SOI substrates combine the benefits of a proven, low-noise FD-SOI platform with a silicon channel enriched with the 28Si isotope. This integration creates a path towards scalable silicon quantum processors leveraging established industrial semiconductor manufacturing processes. Quobly anticipates that these processors will enable advances in areas like materials discovery, energy optimization, and biotechnological modeling, driving innovation across multiple industries.

The collaboration between Soitec, STMicroelectronics, and Quobly is building a European value chain for quantum technology. Soitec manufactures the advanced substrates, STMicroelectronics validates the technology in their 300mm fab, and Quobly focuses on quantum device development. Early performance metrics from these prototype devices are expected in the first quarter of 2026, building upon ST’s existing 28nm FD-SOI process.

Establishing a European Quantum Value Chain

Quobly is establishing a key part of a European quantum value chain through collaboration with Soitec and STMicroelectronics. Soitec provides custom 28Si FD-SOI substrates, now being tested in ST’s 300mm fabrication facility in France. This partnership aims to create a fully integrated supply chain, moving from advanced materials to complete quantum integrated circuits. This milestone builds on over 15 years of research from CEA-Leti and CNRS, combining quantum physics and microelectronics expertise.

These 28Si FD-SOI substrates are engineered to significantly improve quantum processor performance. By eliminating isotopic impurities, these substrates unlock single-qubit gate fidelities approaching 99.999%. This high fidelity is crucial for building reliable and scalable silicon-based quantum processors. Utilizing ST’s existing 28nm FD-SOI process, Quobly is leveraging established semiconductor manufacturing for the creation of potentially millions of physical qubits.

Quobly’s efforts are focused on creating a path toward silicon-based quantum processors, with early performance metrics expected in the first quarter of 2026. The company has secured significant funding, including a record €19 million seed round in 2023 and €21 million in 2025, to advance its Q100T program. Founded in 2022, Quobly aims to bridge the gap between quantum science and industrial manufacturing, enabling scalable and manufacturable quantum computing.

Quobly’s Progress in Quantum Microelectronics

Quobly has achieved a key milestone in industrializing quantum microelectronics with Soitec’s 28Si FD-SOI substrates now being processed within STMicroelectronics’ 300mm fabrication facility. These custom wafers are engineered to minimize isotopic impurities, aiming to drastically reduce quantum noise and unlock single-qubit gate fidelities approaching 99.999%. This achievement establishes a crucial step towards a fully integrated supply chain—from advanced materials to quantum integrated circuits—through the strategic collaboration between Quobly, Soitec, and STMicroelectronics.

These 28Si FD-SOI substrates leverage FD-SOI’s proven low-noise, CMOS-compatible architecture, combined with a 28Si-enriched silicon channel. This combination creates a scalable path toward silicon-based quantum processors benefiting from established industrial semiconductor manufacturing. Quobly anticipates these processors will enable advancements in areas like materials discovery, energy optimization, and biotechnological modeling, ultimately accelerating innovation across various industries.

Early performance metrics from these prototype devices are expected in the first quarter of 2026, building upon ST’s existing 28nm FD-SOI process. Founded in 2022, Quobly has rapidly advanced through collaborative research and significant funding—raising €19 million in 2023 and €21 million in 2025—to support its Q100T program and drive toward fault-tolerant quantum computing. This progress highlights a growing European value chain in quantum technologies.