Development of Large Array of Kinetic Inductance Detectors Using Commercial-Class External Foundries

Abstract

This study focuses on kinetic inductance detectors (KIDs) fabricated in external foundries using 6 and 8-inch processes. These processes allow us to fabricate large arrays of KIDs in a scalable manner. The support of such a wide variety of astronomical and particle-physics applications requires large numbers of superconducting detectors. For example, the sensitivity of the cosmic microwave background measurements has exponentially improved over the past few decades. The most significant advantage of KIDs is scalability to a large array due to the intrinsic frequency multiplexing scheme. The first step of fabricating a large array of KIDs is designing test chips to check the performance of the 6 and 8-inch micro-electro-mechanical system processes. The KIDs are made of a single pure aluminum film and consist of coplanar waveguide quarter wavelength resonators with a feedline. Each wafer is filled with 32 chips, where the chip size is 20 × 20 mm2, with 48 resonators on each chip. The chips are evaluated using a dilution refrigerator at temperatures ranging from 100 to 500 mK. The quality factor of the resonators, temperature dependency of the resonance frequency, and yields are comparable with those of the KIDs fabricated in a dedicated clean room for superconducting detectors.