E. Music

CMOS-Compatible, Wafer-Scale Processed Superconducting Qubits Exceeding Energy Relaxation Times of 200us

  1. T. Mayer,
  2. J. Weber,
  3. E. Music,
  4. C. Moran Guizan,
  5. S. J. K. Lang,
  6. L. Schwarzenbach,
  7. C. Dhieb,
  8. B. Kiliclar,
  9. A. Maiwald,
  10. Z. Luo,
  11. W. Lerch,
  12. D. Zahn,
  13. I. Eisele,
  14. R.N. Pereira,
  15. and C. Kutter
We present the results of an industry-grade fabrication of superconducting qubits on 200 mm wafers utilizing CMOS-established processing methods. By automated waferprober resistance
measurements at room temperature, we demonstrate a Josephson junction fabrication yield of 99.7% (shorts and opens) across more than 10000 junctions and a qubit frequency prediction accuracy of 1.6%. In cryogenic characterization, we provide statistical results regarding energy relaxation times of the qubits with a median T1 of up to 100 us and individual devices consistently approaching 200 us in long-term measurements. This represents the best performance reported so far for superconducting qubits fabricated by industry-grade, wafer-level subtractive processes.
arxiv pdf

Advancing Superconducting Qubits: CMOS-Compatible Processing and Room Temperature Characterization for Scalable Quantum Computing beyond 2D Architectures

  1. S. J. K. Lang,
  2. T. Mayer,
  3. J. Weber,
  4. C. Dhieb,
  5. I. Eisele,
  6. W. Lerch,
  7. Z. Luo,
  8. C. Moran Guizan,
  9. E. Music,
  10. L. Sturm-Rogon,
  11. D. Zahn,
  12. R.N. Pereira,
  13. and C. Kutter
We report on an industry-grade CMOS-compatible qubit fabrication approach using a CMOS pilot line, enabling a yield of functional devices reaching 92.8%, with a resistance spread evaluated
across the full wafer 200 mm diameter of 12.4% and relaxation times (T1) approaching 80 us. Furthermore, we conducted a comprehensive analysis of wafer-scale room temperature (RT) characteristics collected from multiple wafers and fabrication runs, focusing on RT measurements and their correlation to low temperature qubit parameters. From defined test structures, a across-wafer junction area variation of 10.1% and oxide barrier variation of 7.2% was calculated. Additionally, we notably show a close-correlation between qubit junction resistance and frequency in accordance with the Ambegaokar-Baratoff relation with a critical temperature Tc of about 0.71 K. This overarching relation sets the stage for pre-cooldown qubit evaluation and sorting. In particular, such early-on device characterization and validation are crucial for increasing the fabrication yield and qubit frequency targeting, which currently represent major scaling challenges. Furthermore, it enables the fabrication of large multichip quantum systems in the future. Our findings highlight the great potential of CMOS-compatible industry-style fabrication of superconducting qubits for scalable quantum computing in a foundry pilot line cleanroom.
arxiv pdf