L. Schwarzenbach

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

3D-Integrated Superconducting qubits: CMOS-Compatible, Wafer-Scale Processing for Flip-Chip Architectures

  1. T. Mayer,
  2. H. Bender,
  3. S. J. K. Lang,
  4. Z. Luo,
  5. J. Weber,
  6. C. Moran Guizan,
  7. C. Dhieb,
  8. D. Zahn,
  9. L. Schwarzenbach,
  10. W. Hell,
  11. M. Andronic,
  12. A. Drost,
  13. K. Neumeier,
  14. W. Lerch,
  15. L. Nebrich,
  16. A. Hagelauer,
  17. I. Eisele,
  18. R.N. Pereira,
  19. and C. Kutter
In this article, we present a technology development of a superconducting qubit device 3D-integrated by flip-chip-bonding and processed following CMOS fabrication standards and contamination
rules on 200 mm wafers. We present the utilized proof-of-concept chip designs for qubit- and carrier chip, as well as the respective front-end and back-end fabrication techniques. In characterization of the newly developed microbump technology based on metallized KOH-etched Si-islands, we observe a superconducting transition of the used metal stacks and radio frequency (RF) signal transfer through the bump connection with negligible attenuation. In time-domain spectroscopy of the qubits we find high yield qubit excitation with energy relaxation times of up to 15 us.
arxiv pdf