Superconducting airbridge crossover using superconducting sacrificial material
View Patent ↗A technique relates to a superconducting airbridge on a structure. A first ground plane, resonator, and second ground plane are formed on a substrate. A first lift-off pattern is formed of a first lift-off resist and a first photoresist. The first photoresist is deposited on the first lift-off resist. A superconducting sacrificial layer is deposited while using the first lift-off pattern. The first lift-off pattern is removed. A cross-over lift-off pattern is formed of a second lift-off resist and a second photoresist. The second photoresist is deposited on the second lift-off resist. A cross-over superconducting material is deposited to be formed as the superconducting airbridge while using the cross-over lift-off pattern. The cross-over lift-off pattern is removed. The superconducting airbridge is formed to connect the first and second ground planes by removing the superconducting sacrificial layer underneath the cross-over superconducting material. The superconducting airbridge crosses over the resonator.
1. A superconducting microwave structure comprising:
a first ground plane, a resonator, and a second ground plane formed on a substrate;
a superconducting airbridge connecting the first ground plane and the second ground plane, the superconducting airbridge having an airgap underneath from where a superconducting sacrificial layer has been removed; and
a residual portion of the superconducting sacrificial layer remaining on at least one of the first ground plane, the resonator, the second ground plane, and the superconducting airbridge;
wherein the first ground plane, the resonator, the second ground plane, and the superconducting airbridge are made of a superconducting material, the superconducting material is selected from the group consisting of aluminum and titanium nitride; and
wherein the residual portion is selected from the group consisting of niobium and tantalum.