Applications of Thin Film Atomic Layer Deposition Superconducting Titanium Nitride to Astronomical Measurements

Microwave Kinetic Inductance Detectors (MKIDs) are an appealing option for conducting millimeter-wave astronomy and measuring the Cosmic Microwave Background due to their ease of fabrication and multiplexing. MKIDs make detections when a microwave photon breaks Cooper pairs in the superconducting metal, modifying the kinetic inductance of the metal and the resonant frequency of the on-chip resonator. A material of interest for fabricating MKIDs is Atomic Layer Deposition titanium nitride (ALD TiN) due to its high kinetic inductance and low critical temperature. We can precisely control these characteristics of the TiN by tuning deposition parameters such as thickness, stage temperature, and nitrogen flow. This method also admits high quality factors, allowing for increased multiplexing, and wafer-level uniformity with film thicknesses in the range of 4-18 nm. We present measurements of the critical temperature and internal quality factor of ALD TiN resonators under the variation of various ALD parameters as it relates to fabricating MKIDs.