The Simons Observatory: Production-Level Fabrication of the Mid- and Ultra-High-Frequency Wafers

Shannon M. Duff, Jason Austermann, James A. Beall, David P. Daniel, Johannes Hubmayr, Greg C. Jaehnig, Bradley R. Johnson, Dante Jones, Michael J. Link, Tammy J. Lucas, Rita F. Sonka, Suzanne T. Staggs, Joel Ullom, Yuhan Wang

Research output: Contribution to journalArticlepeer-review


The Simons Observatory (SO) is a cosmic microwave background instrumentation suite in the Atacama Desert of Chile. More than 65,000 polarization-sensitive transition-edge sensor (TES) bolometers will be fielded in the frequency range spanning 27 to 280 GHz, with three separate dichroic designs. The mid-frequency 90/150 GHz and ultra-high-frequency 220/280 GHz detector arrays, fabricated at NIST, account for 39 of 49 total detector modules and implement the feedhorn-fed orthomode transducer-coupled TES bolometer architecture. A robust production-level fabrication framework for these detector arrays and the monolithic DC/RF routing wafers has been developed, which includes single device prototyping, process monitoring techniques, in-process metrology, and cryogenic measurements of critical film properties. Application of this framework has resulted in timely delivery of nearly 100 total superconducting focal plane components to SO with 88% of detector wafers meeting nominal criteria for integration into a detector module: a channel yield >95% and Tc in the targeted range.

Original languageEnglish (US)
JournalJournal of Low Temperature Physics
StateAccepted/In press - 2024

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • General Materials Science
  • Condensed Matter Physics


  • Bolometer
  • CMB
  • Microfabrication
  • Transition-edge sensor


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