Advanced ACTPol Multichroic Polarimeter Array Fabrication Process for 150 mm Wafers
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Advanced ACTPol (AdvACT) is a third-generation cosmic microwave background receiver to be deployed in 2016 on the Atacama Cosmology Telescope (ACT). Spanning five frequency bands from 25 to 280 GHz and having just over 5600 transition-edge sensor (TES) bolometers, this receiver will exhibit increased sensitivity and mapping speed compared to previously fielded ACT instruments. This paper presents the fabrication processes developed by NIST to scale to large arrays of feedhorn-coupled multichroic AlMn-based TES polarimeters on 150-mm diameter wafers. In addition to describing the streamlined fabrication process which enables high yields of densely packed detectors across larger wafers, we report the details of process improvements for sensor (AlMn) and insulator (SiN\(_x\)) materials and microwave structures, and the resulting performance improvements.
KeywordsAlMn Multichroic Polarimeter SiN\(_x\) Transition-edge sensor
This work was supported by the U.S. National Science Foundation through award 1440226. The NIST authors would like to acknowledge the support of the NIST Quantum Initiative. The development of multichroic detectors and lenses was supported by NASA grants NNX13AE56G and NNX14AB58G. The work of BJK, BLS, JTW, and SMS was supported by NASA Space Technology Research Fellowship awards.
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