LAYERS 9 – Superconducting thin films for Quantum Computing
Quantum computing based on superconducting qubits is one of the most advanced approaches currently under development. Central to this technology are superconducting thin films, which enable zero‑resistance current flow, ultra‑low‑loss resonators, and reliable interconnects. Materials such as niobium, niobium titanium alloys, tantalum, niobium nitride, and indium form the backbone of many qubit architectures used today.
To move beyond laboratory demonstrations and toward reproducible wafer‑scale fabrication, thin film deposition processes must deliver high material purity, precise control of film structure, and stable electrical performance. Physical Vapor Deposition processes including sputtering, evaporation, and co‑evaporation offer the level of control required for these demanding applications and are compatible with semiconductor manufacturing environments.
Superconducting thin films deposited by PVD are used across several quantum computing elements. These include Josephson junction qubits based on niobium and aluminum electrodes, multilayer stacks with tunable critical temperatures using titanium or niobium titanium alloys, and low‑loss interconnect layers such as indium for multi‑chip integration. PVD technologies also play an important role in hybrid photonic integration, where superconducting elements are combined with optical waveguides, modulators, and detectors on a single chip.
Results presented from Evatec systems demonstrate how sputtering of niobium and alpha tantalum can achieve the required crystal structure, low surface roughness, uniform resistivity, and stable superconducting transition temperatures. Film stress and surface morphology can be tuned through process parameters to meet integration requirements. In addition, co‑evaporation processes enable precise control of alloy composition in niobium titanium films, allowing adjustment of the superconducting transition temperature while maintaining long‑term stability.
Together, these results highlight how manufacturing‑ready PVD processes provide a reliable pathway from quantum research toward scalable production of superconducting quantum devices.
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