Germany's first cryogenic measuring setup for the statistical quality measurement of qubit devices on 200- and 300-mm wafers has commenced operation at Fraunhofer IAF. With the newly established cryogenic on-wafer prober, researchers at the Fraunhofer Institute for Applied Solid State Physics IAF aim to gain a deeper understanding of the functioning of quantum devices based on semiconductor quantum dots, quantum wells, and superconductors.
The device can characterize wafers in industrial sizes (200 mm and 300 mm) and high volumes (up to 25 wafers in a row) fully automatically at cryogenic temperatures below 2 K (271.15°C). The datasets obtained significantly reduce the reliance on random measurements, a characteristic of single measurements. This expansion of measurement capacities at the institute contributes to the development of reliable production of high-quality qubits, which can be employed in quantum computers and quantum sensors.
At the time of its commissioning, this facility is the fifth of its kind worldwide, the second in Europe, and the first in Germany. The German Federal Ministry of Education and Research (BMBF) funded the procurement and installation of the wafer prober as part of the 'KryoproPlus — Provision and Verification of a Cryogenic On-Wafer Prober' project.
"With the on-wafer prober, we gain new and unique capabilities in cryogenic characterization nationwide," emphasizes Rüdiger Quay, KryoproPlus project coordinator and acting institute director of Fraunhofer IAF. "With this system, we will support our partners from both research and industry in establishing a European supply chain for materials and production processes for solid-state qubits. This allows us to make an important contribution to the technological sovereignty of Germany and Europe," Quay adds.
"The wafer prober provides us, for the first time, with statistically relevant datasets that we can use to systematically optimize and scale the production of qubit devices," explains Nikola Komerički, who is supervising the KryoproPlus project as part of his doctoral work on the characterization of quantum computing devices. Komerički coordinated the installation and commissioning of the system and is already conducting the first measurements.
"We want to better understand how to achieve good, homogeneous qubits to enable scaling and industrial production of qubits in Germany and Europe," Komerički adds. "To do that, it is necessary to expand the qualitative view to include a quantitative, statistical perspective on device behavior."
Improved data is obtained through automated measurements of entire 200 mm and 300 mm wafers at temperatures below 2 K. Qubits based on semiconductor quantum dots, quantum wells, and superconductors operate at temperatures close to absolute zero (-273.15 °C). This minimizes ambient interference, activates superconductivity, and enables the formation and entanglement of qubits. Therefore, it is essential for testing, optimization, and scaling of qubits that they are characterized at their operating temperature, and a statistically evaluable set of measurement data is collected.
The cryogenic on-wafer prober addresses this characterization gap. The automated measurement of entire 200 mm and 300 mm wafers at temperatures below 2 K, with a short changeover time, increases the available data significantly. This data provides researchers and engineers with the necessary foundation to make targeted improvements to qubit formation devices and enhance scalability.
With the full commissioning of the wafer prober, the KryoproPlus project has been completed. The initial measurements from the facility are part of the 'MATQu — Materials for Quantum Computing,' 'QUASAR — Semiconductor Quantum Processor with Shuttling-based Scalable Architecture,' and 'QLSI — Large Scale Quantum Integration with Silicon' projects.
For MATQu, Komerički is characterizing and analyzing (niobium) Josephson junctions, which are devices for transmon qubits. For QUASAR and QLSI, characterizations of FETs for single-electron transistors (SETs) based on silicon quantum wells, and subsequently SETs that serve as devices for spin qubits, are being conducted.
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Image: Fraunhofer IAF announces Germany’s first cryogenic on-wafer statistical measurement system for qubit devices. Credit: Fraunhofer IAF
Source: Compound Semiconductor
