Electroplated Tin Absorbers in Microcalorimeter Detectors for Ionizing Radiation

Abstract

State-of-the-art microcalorimeter gamma-ray detectors 1, 2 show promise for nuclear material characterization because their spectral resolution is substantially better than high purity germanium sensors. Microcalorimeter detectors have been fabricated and tested by National Institute of Standards and Technology (NIST) and Los Alamos National Laboratory (LANL) by combining microfabricated transition edge sensors (TESs) with bulk tin gamma-ray absorbers. The ability to integrate the tin electroplating into the microfabrication process has potential benefits for performance, scalability, reliability, and ease of manufacturing.This work investigates a commercially available tin/silver chemistry traditionally used for 3-D semiconductor packaging. Samples were electroplated on a sacrificial substrate changing chemistry makeup, current density, and time to realize pure tin deposition at thicknesses of 380-400 micron. Characterization was performed using SEM, EDS, XRF, and XPS and compared to bulk tin properties used in past microcalorimeter devices. The electroplated tin samples were diced into individual 1.3x1.3 mm sizes and integrated with TES detectors at NIST and LANL. The assembled devices were tested with gamma radiation sources to evaluate performance. This work will provide an overview of the project, current progress, and future ideas for realizing a fully integrated microcalorimeter fabrication process. D. A. Bennett, R. D. Horansky, D. R. Schmidt, A. S. Hoover, R. Winkler, B. K. Alpert, J. A. Beall, W. B. Doriese, J. W. Fowler, C. P. Fitzgerald, G. C. Hilton, K. D. Irwin, V. Kotsubo, J. A. B. Mates, G. C. O'Neil, M. W. Rabin, C. D. Reintsema, F. J. Schima, D. S. Swetz, L. R. Vale, and J. N. Ullom, Rev Sci Instrum, 83 (9), (2012).D. T. Becker, B. K. Alpert, D. A. Bennett, M. P. Croce, J. W. Fowler, J. D. Gard, A. S. Hoover, Y. I. Joe, K. E. Koehler, J. A. B. Mates, G. C. O'Neil, M. W. Rabin, C. D. Reintsema, D. R. Schmidt, D. S. Swetz, P. Szypryt, L. R. Vale, A. L. Wessels, and J. N. Ullom, Ieee T Nucl Sci, 66 (12), 2355-2363 (2019). Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525, SAND2020-5481 A . The views expressed in the article do not necessarily represent the views of the U.S. Department of Energy or the United States Government.