Kavli Affiliate: Oskar Painter
| First 5 Authors: Neha Mahuli, Neha Mahuli, , ,
| Summary:
We present a dry surface treatment combining atomic layer etching and
deposition (ALE and ALD) to mitigate dielectric loss in fully fabricated
superconducting quantum devices formed from aluminum thin films on silicon. The
treatment, performed as a final processing step prior to device packaging,
starts by conformally removing the native metal oxide and fabrication residues
from the exposed surfaces through ALE before textitin situ encapsulating the
metal surfaces with a thin dielectric layer using ALD. We measure a two-fold
reduction in loss attributed to two-level system (TLS) absorption in treated
aluminum-based resonators and planar transmon qubits. Treated transmons with
compact capacitor plates and gaps achieve median $Q$ and $T_1$ values of $3.69
pm 0.42 times 10^6$ and $196 pm 22$~$mu$s, respectively. These improvements
were found to be sustained over several months. We discuss how the combination
of ALE and ALD reverses fabrication-induced surface damages to significantly
and durably improve device performance via a reduction of the TLS defect
density in the capacitive elements.
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