Resist-free shadow deposition using silicon trenches for Josephson junctions in superconducting qubits

Quantum Physics [Submitted on 10 Apr 2026] Resist-free shadow deposition using silicon trenches for Josephson junctions in superconducting qubits Tathagata Banerjee, Stephen Daniel Funni, Saswata Roy, Judy J. Cha, Valla Fatemi Superconducting qubit fabrication innovations continue to be explored to achieve higher performance. Despite improvements to base layer fabrication and processing, resist-based Josephson junction (JJ) schemes have largely remained unchanged. The polymer mask during deposition causes chemical contamination and limits in situ and ex situ surface preparation, junction materials, and scalability. Here, we demonstrate a resist-free approach to junction fabrication based on etched silicon trenches that is CMOS compatible and easily integrated into existing innovations in qubit base layer fabrication and chemical processing. We fabricate Al-AlOx-Al JJs and qubits using this method, measuring median energy relaxation times up to 184 microseconds. We find minimal contamination at the substrate-metal interface and fluctuations of energy relaxation on a 35 hour timescale that are narrow and normally distributed. The method widens the process window for substrate preparation and new materials platforms. Comments: 7 pages, 5 figures, supplementary material (9 pages, 9 figures, 2 tables) Subjects: Quantum Physics (quant-ph); Applied Physics (physics.app-ph) Cite as: arXiv:2604.09796 [quant-ph]   (or arXiv:2604.09796v1 [quant-ph] for this version)   https://doi.org/10.48550/arXiv.2604.09796 Focus to learn more Submission history From: Tathagata Banerjee [view email] [v1] Fri, 10 Apr 2026 18:19:18 UTC (11,747 KB) Access Paper: HTML (experimental) view license Current browse context: quant-ph < prev   |   next > new | recent | 2026-04 Change to browse by: physics physics.app-ph References & Citations INSPIRE HEP NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)