Fabrication effects on Niobium oxidation and surface contamination in Niobium-metal bilayers using X-ray photoelectron spectroscopy

Abstract

Superconducting resonators and qubits are limited by dielectric losses from surface oxides. Surface oxides are mitigated through various strategies such as the addition of a metal capping layer, surface passivation, and acid processing. In this study, we demonstrate the use of X-ray photoelectron spectroscopy (XPS) as a rapid characterization tool to study the effectiveness cap layers for niobium for further device fabrication. We non-destructively evaluate 17 capping layers to characterize their ability to prevent oxygen diffusion, and the effects of standard fabrication processes -- annealing, resist stripping, and acid cleaning. We downselect for resilient capping layers and test their microwave resonator performance.

References in corpus (19)

• New material platform for superconducting transmon qubits with coherence times exceeding 0.3 milliseconds
• An analysis method for asymmetric resonator transmission applied to superconducting devices
• Materials loss measurements using superconducting microwave resonators
• Surface loss simulations of superconducting coplanar waveguide resonators
• Three-dimensional superconducting resonators at $T<20$ mK with the photon lifetime up to $\tau =2$ seconds
• Systematic Improvements in Transmon Qubit Coherence Enabled by Niobium Surface Encapsulation
• Characterization and reduction of microfabrication-induced decoherence in superconducting quantum circuits
• Investigation of microwave loss induced by oxide regrowth in high-Q Nb resonators
• Disentangling Losses in Tantalum Superconducting Circuits
• Analysis of high quality superconducting resonators: consequences for TLS properties in amorphous oxides
• TOF-SIMS Analysis of Decoherence Sources in Nb Superconducting Resonators
• Nitrogen Plasma Passivated Niobium Resonators for Superconducting Quantum Circuits
• On the quest of low temperature nitrogen infusion relevant for superconducting Nb based radio-frequency cavities
• Formation and Microwave Losses of Hydrides in Superconducting Niobium Thin Films Resulting from Fluoride Chemical Processing
• Oxygen Vacancies in Niobium Pentoxide as a Source of Two-Level System Losses in Superconducting Niobium
• Wafer-scale uniformity of Dolan-bridge and bridgeless Manhattan-style Josephson junctions for superconducting quantum processors
• Low loss hybrid Nb/Au superconducting resonators for quantum circuit applications
• Low barrier ZrO${}_x$-based Josephson junctions
• Active-Learning Inspired $\text{Ab Initio}$ Theory-Experiment Loop Approach for Management of Material Defects: Application to Superconducting Qubits