Krypton Sputtering Grows bcc Tantalum at 200°C, Lifting Qubit Quality Factors to 16.9 Million
Updated
Updated · Nature.com · Aug 18
Krypton Sputtering Grows bcc Tantalum at 200°C, Lifting Qubit Quality Factors to 16.9 Million
2 articles · Updated · Nature.com · Aug 18
Summary
Researchers deposited cubic bcc tantalum films directly on silicon at 200°C by switching the sputter gas from argon to krypton, cutting the temperature from the 400°C-plus typically needed.
That lower-temperature process opens a wider back-end-of-line-compatible fabrication window for quantum chips while still producing resonators with a tight, high-performance loss distribution.
Measurements showed hotter-grown films performed worse, with higher microwave losses tracking greater tantalum-silicon intermixing at the interface.
Using the krypton-sputtered films, the team built transmon qubits with a compact 20-μm capacitor gap and achieved quality factors of up to 16.9 million.
The result strengthens tantalum's case as a scalable material platform for superconducting qubits and resonators in quantum computing hardware.