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Published September 2015 | public
Journal Article

Fabrication of large dual-polarized multichroic TES bolometer arrays for CMB measurements with the SPT-3G camera

Abstract

This work presents the procedures used at Argonne National Laboratory to fabricate large arrays of multichroic transition-edge sensor (TES) bolometers for cosmic microwave background (CMB) measurements. These detectors will be assembled into the focal plane for the SPT-3G camera, the third generation CMB camera to be installed in the South Pole Telescope. The complete SPT-3G camera will have approximately 2690 pixels, for a total of 16 140 TES bolometric detectors. Each pixel is comprised of a broad-band sinuous antenna coupled to a Nb microstrip line. In-line filters are used to define the different bands before the millimeter-wavelength signal is fed to the respective Ti/Au TES bolometers. There are six TES bolometer detectors per pixel, which allow for measurements of three band-passes (95, 150 and 220 GHz) and two polarizations. The steps involved in the monolithic fabrication of these detector arrays are presented here in detail. Patterns are defined using a combination of stepper and contact lithography. The misalignment between layers is kept below 200 nm. The overall fabrication involves a total of 16 processes, including reactive and magnetron sputtering, reactive ion etching, inductively coupled plasma etching and chemical etching.

Additional Information

© 2015 IOP Publishing Ltd. Received 30 April 2015, revised 26 June 2015; Accepted for publication 8 July 2015; Published 11 August 2015. This work was supported in part by the Office of Science and the Office of Basic Energy Sciences of the US Department of Energy under Contract DE-AC02-06CH11357; by the National Science Foundation (NSF) under Grant ANT-0638937; by the NSF Physics Frontiers Center under Grant PHY-1125897; by The Kavli Foundation; by the Gordon and Betty Moore Foundation; and by the NSF under Grants AST-0956135 and AST-1402161. Technical support from the Nanofabrication Group at the Center for Nanoscale Materials, Argonne National Laboratory, is gratefully appreciated.

Additional details

Created:
August 20, 2023
Modified:
October 24, 2023