Annealing reduces Si3⁢N4 microwave-frequency dielectric loss in superconducting resonators

The dielectric loss of silicon nitride (Si3⁢N4) limits the performance of microwave-frequency devices that rely on this material for sensing, signal processing, and quantum communication. Using superconducting resonant circuits, we measure the cryogenic loss tangent of either as-deposited or high-temperature annealed stoichiometric Si3⁢N4 as a function of drive strength and temperature.