Niobium titanium nitride (NbTiN)

Niobium titanium nitride (NbTiN) is a refractory nitride alloy whose Ti incorporation raises critical current density and lowers surface resistance while preserving the ∼15 K superconducting transition, high hardness, and chemical inertness. It is routinely deposited by reactive magnetron sputtering for dense, uniform films and by atomic layer deposition (ALD) when conformal, thickness‑precise coatings are needed on deep or temperature‑sensitive structures. Thanks to its low microwave loss and high kinetic inductance, NbTiN underpins superconducting resonators, filters, parametric amplifiers, Josephson‑junction qubits, and rapid single‑flux‑quantum logic for quantum and ultralow‑noise electronics. Ultrathin NbTiN nanowires form state‑of‑the‑art superconducting nanowire single‑photon detectors (SNSPDs) and kinetic‑inductance detectors with high detection efficiencies, low dark counts, and fast reset times. Its tunable plasma frequency and stability enable mid‑IR/THz plasmonic structures, hot‑electron bolometers, and ENZ‑based modulators, while patterned NbTiN heaters exploit its robust metallic phase above the critical temperature. Beyond quantum and photonics, NbTiN’s wear and oxidation resistance make it a durable diffusion‑barrier, cutting‑tool, and MEMS protective coating, cementing its versatility across superconducting, optical, and engineering applications.

Deposition of Niobium Titanium Nitride

Deposition of NbTiN can be done by reactive sputtering using NbTi target.

The preferred tool for this application is the Cluster-based multi-chamber high vacuum sputtering deposition system, commonly referred to as the 'Cluster Lesker.' The operating process is thoroughly documented and described in detail.:

Deposition of Niobium Titanium Nitride using reactive p-DC sputtering in Sputter-System Metal-Nitride(PC3) Source 1 (4-inch target)

At the moment (October 2023) we have a 4-inch NbTi target for PC3 Src1 and a 3-inch NbTi target for Sputter-System Lesker (Old Lesker).

Comparison of sputter systems for nitride deposition

	Sputter-System Metal-Nitride(PC3)	Lesker sputter system
Generel description	Pulsed DC reactive sputtering Reactive HIPIMS (high-power impulse magnetron sputtering) (require 3-inch target)	Reactive DC sputtering (not tested)
Stoichiometry	Nb_xT_yN (Sputter-System Metal-Nitride(PC3)) Tunable composition	Unknown
Film thickness	Limited by process time. Deposition rate (0.18 nm/s) likely faster than Sputter-System (Lesker)	Limited by process time. Deposition rate unknown
Process temperature	Up to 600 °C	Up to 400 °C
Step coverage	Some step coverage possible	Some step coverage possible but amount unknown
Film quality	Deposition on one side of the substrate Properties including tunable stoichiometry (requires process development)	Deposition on one side of the substrate Unknown quality Likely O-contamination
Batch size	Many smaller samples Up to 10*100 mm or 150 mm wafers	Several smaller samples 1-several 50 mm wafers 1100 mm wafers 1150 mm wafer
Allowed materials	Almost any as long as they do not outgas and are not very toxic, see cross-contamination sheets	Almost any as long as they do not outgas and are not very toxic, see cross-contamination sheets