Fabrication of Feedhorn-Coupled Transition Edge Sensor Arrays for Measurement of the Cosmic Microwave Background Polarization

• Published in: Journal of low temperature physics Vol. 184; no. 3-4; pp. 668 - 673
• Main Authors: Denis, K. L., Ali, A., Appel, J., Bennett, C. L., Chang, M. P., Chuss, D. T., Colazo, F. A., Costen, N., Essinger-Hileman, T., Hu, R., Marriage, T., Rostem, K., U-Yen, K., Wollack, E. J.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.08.2016
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Magnetic Materials; Magnetism; Physics; Physics and Astronomy; Wafer bonding; Polarization; CMB; Micro-machining; TES
• ISSN: 0022-2291; 1573-7357
• DOI: 10.1007/s10909-015-1366-y

Characterization of the minute cosmic microwave background polarization signature requires multi-frequency, high-throughput precision instrument systems. We have previously described the detector fabrication of a 40 GHz focal plane and now describe the fabrication of detector modules for measurement of the CMB at 90 GHz. The 90 GHz detectors are a scaled version of the 40 GHz architecture where, due to smaller size detectors, we have implemented a modular (wafer level) rather than the chip-level architecture. The new fabrication process utilizes the same design rules with the added challenge of increased wiring density to the 74 TES’s as well as a new wafer level hybridization procedure. The hexagonally shaped modules are tile-able, and as such can be used to form the large focal planes required for a space-based CMB polarimeter. The detectors described here will be deployed in two focal planes with seven modules each in the Johns Hopkins University led ground-based Cosmology Large Angular Scale Surveyor (CLASS) telescope.