Fabrication of OMT-Coupled Kinetic Inductance Detector for CMB Detection

Future cosmic microwave background (CMB) experiments, including the large scale ground-based Stage Four CMB Experiment (CMB-S4), satellites, and balloons, aim to map the CMB to an unprecedented precision in order to answer several key questions in cosmology. However, to reach the target noise sensit...

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Bibliographic Details
Published in:Journal of low temperature physics 2020-04, Vol.199 (1-2), p.362-368
Main Authors: Tang, Q. Y., Barry, P. S., Cecil, T. W., Shirokoff, E.
Format: Article
Language:English
Subjects:
Aluminum
Arrays
Big Bang theory
Characterization and Evaluation of Materials
Condensed Matter Physics
Cosmic microwave background
Cosmology
Detectors
fabrication
Frequencies
Inductance
kinetic inductance detector
Low temperature physics
Magnetic Materials
Magnetism
Microstrip transmission lines
Multiplexing
Niobium
Noise sensitivity
OTHER INSTRUMENTATION
Physics
Physics and Astronomy
Prototypes
Sensors
Silicon
Substrates
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Summary:Future cosmic microwave background (CMB) experiments, including the large scale ground-based Stage Four CMB Experiment (CMB-S4), satellites, and balloons, aim to map the CMB to an unprecedented precision in order to answer several key questions in cosmology. However, to reach the target noise sensitivity, more than 100,000 detectors will be needed. Arrays of kinetic inductance detectors (KIDs) are a promising alternative for experiments that require large number of detectors due to the intrinsic multiplexing capabilities. We present the fabrication procedure for a prototype planar orthomode transducer (OMT)-coupled multi-color KID array optimized for 220/270 GHz frequency bands. These devices are made from silicon-on-insulator wafers to provide a low-loss substrate for the KIDs. The OMT couples the two polarizations of light from a wide-band feedhorn to separate Nb/SiN/Nb microstrip lines, which are then coupled to Al/Nb lumped-element KIDs (LEKIDs). The silicon on the backside of the OMT is etched away using deep reactive ion etch to release the OMT membrane to enable operation over a wide bandwidth. Finally, the buried oxide is removed underneath the KID capacitors in order to minimize two-level system noise and loss mitigation. We achieved a good yield (> 80%) on our prototype devices.
ISSN:0022-2291
1573-7357
DOI:10.1007/s10909-020-02341-5