Fabrication of Detector Arrays for the SPT-3G Receiver

The South Pole Telescope third-generation (SPT-3G) receiver was installed during the austral summer of 2016–2017. It is designed to measure the cosmic microwave background across three frequency bands centered at 95, 150, and 220 GHz. The SPT-3G receiver has ten focal plane modules, each with 269 pixels. Each pixel features a broadband sinuous antenna coupled to a niobium microstrip transmission line. In-line filters define the desired band-passes before the signal is coupled to six bolometers with Ti/Au/Ti/Au transition edge sensors (three bands \(\times \) two polarizations). In total, the SPT-3G receiver is composed of 16,000 detectors, which are read out using a 68\(\times \) frequency-domain multiplexing scheme. In this paper, we present the process employed in fabricating the detector arrays.