Tile-and-trim micro-resonator array fabrication optimized for high multiplexing factors

TL;DR

This paper introduces a scalable, reconfigurable fabrication method for superconducting micro-resonator arrays, optimized for high multiplexing, demonstrated on a 101-element MKID array with high yield and precise frequency control.

Contribution

The authors develop a tile-and-trim fabrication technique for MKID arrays that enhances scalability and multiplexing capacity, with demonstrated high yield and optimized frequency spacing.

Findings

Achieved a 1836-resonator array with high yield.

Fractional frequency spacing deviations are primarily smooth and predictable.

Yield aligns with models of frequency collision and is comparable to other low-temperature detectors.

Abstract

We present a superconducting micro-resonator array fabrication method that is scalable, reconfigurable, and has been optimized for high multiplexing factors. The method uses uniformly sized tiles patterned on stepper photolithography reticles as the building blocks of an array. We demonstrate this technique on a 101-element microwave kinetic inductance detector (MKID) array made from a titanium-nitride superconducting film. Characterization reveals 1.5\% maximum fractional frequency spacing deviations caused primarily by material parameters that vary smoothly across the wafer. However, local deviations exhibit a Gaussian distribution in fractional frequency spacing with a standard deviation of $2.7 \times 10^{-3}$. We exploit this finding to increase the yield of the BLAST-TNG $250 \; \mu\text{m}$ production wafer by placing resonators in the array close in both physical and frequency space. This array consists of 1836 polarization-sensitive MKIDs wired in three multiplexing groups. We present the array design and show that the achieved yield is consistent with our model of frequency collisions and is comparable to what has been achieved in other low temperature detector technologies.