Qubit fabrication in advanced semiconductor manufacturing facilities: the good, the bad, and the ugly*

The performance of modern superconducting and spin qubits, including their fidelity and homogeneity, is limited by material quality issues – especially, interfacial purity and cleanliness. The advanced process control in modern, industry- and foundry-grade manufacturing facilities can result in ultraclean and well controlled interfaces, while providing stringent limitations in the allowed processing methods. In this talk, we present recent results on improvements over the state-of-the art in interface and materials control in both superconducting and silicon spin qubit platforms: best-in-class quality factors of superconducting resonators [1], ultra-low charge noise in MOS spin qubits, and initial results in reduced variability for superconducting qubits [2]. At the same time, the incompatibility of relatively simple techniques such as lift-off with those advanced processing methods results in major constraints for qubit manufacturing. Overcoming those constraints while still leveraging the advantages in process control is the ugly side, the progress of which we will describe in detail.

[1] Verjauw et al., Phys. Rev. Applied 16, 014018 (2021)

[2] Verjauw et al., npj Quantum Information 8, 93 (2022)