Commercialization of micro-fabrication of antenna-coupled Transition Edge Sensor bolometer detectors for studies of the Cosmic Microwave Background

We report on the development of commercially fabricated multi-chroic antenna coupled Transition Edge Sensor (TES) bolometer arrays for Cosmic Microwave Background (CMB) polarimetry experiments. CMB polarimetry experiments have deployed instruments in stages. Stage-II experiments deployed with O(1,000) detectors and reported successful detection of B-mode (divergent free) polarization pattern in the CMB. Stage-III experiments have recently started observing with O(10,000) detectors with wider frequency coverage. A concept for a Stage-IV experiment, CMB-S4, is emerging to make a definitive measurement of CMB polarization from the ground with O(400,000) detectors. The orders of magnitude increase in detector count for CMB-S4 requires a new approach in detector fabrication to increase fabrication throughput.and reduce cost. We report on collaborative efforts with two commercial micro-fabrication foundries to fabricate antenna coupled TES bolometer detectors. The detector design is based on the sinuous antenna coupled dichroic detector from the POLARBEAR-2 experiment. The TES bolometers showed the expected I-V response and the RF performance agrees with simulation. We will discuss the motivation, design consideration, fabrication processes, test results, and how industrial detector fabrication could be a path to fabricate hundreds of detector wafers for future CMB polarimetry experiments.