Improvements in circuit design and more recently in materials and surface cleaning have contributed to a rapid development of coherent superconducting qubits. However, organic resists commonly used for shadow evaporation of Josephson junctions (JJs) pose limitations due to residual contamination, poor thermal stability and compatibility under typical surface-cleaning conditions. To provide an alternative, we developed an inorganic SiO2/Si3N4 on-chip stencil lithography mask for JJ fabrication. The stencil mask is resilient to aggressive cleaning agents and it withstands high temperatures up to 1200{\deg}C, thereby opening new avenues for JJ material exploration and interface optimization. To validate the concept, we performed shadow evaporation of Al-based transmon qubits followed by stencil mask lift-off using vapor hydrofluoric acid, which selectively etches SiO2. We demonstrate average T1≈75±11μs over a 200 MHz frequency range in multiple cool-downs for one device, and T1≈44±8μs for a second device. These results confirm the compatibility of stencil lithography with state-of-the-art superconducting quantum devices and motivate further investigations into materials engineering, film deposition and surface cleaning techniques.
@article{arxiv.2507.17005,
title = {On-chip stencil lithography for superconducting qubits},
author = {Roudy Hanna and Sören Ihssen and Simon Geisert and Umut Kocak and Matteo Arfini and Albert Hertel and Thomas J. Smart and Michael Schleenvoigt and Tobias Schmitt and Joscha Domnick and Kaycee Underwood and Abdur Rehman Jalil and Jin Hee Bae and Benjamin Bennemann and Mathieu Féchant and Mitchell Field and Martin Spiecker and Nicolas Zapata and Christian Dickel and Erwin Berenschot and Niels Tas and Gary A. Steele and Detlev Grützmacher and Ioan M. Pop and Peter Schüffelgen},
journal= {arXiv preprint arXiv:2507.17005},
year = {2026}
}