Superconducting device with dummy elements
Examples described in this disclosure relate to superconducting devices, including reciprocal quantum logic (RQL) compatible devices. A superconducting device including at least one superconducting element having a first coefficient of thermal expansion is provided. The at least one superconducting element is formed on a dielectric layer having a second coefficient of thermal expansion and the first coefficient of thermal expansion is different from the second coefficient of thermal expansion causing a strain mismatch between the at least one superconducting element and the dielectric layer when the superconducting device is operating in a cryogenic environment. The superconducting device may also include at least one dummy element configured to lower stress at an interface between the at least one superconducting element and the dielectric layer when the at least one superconducting device is operating in the cryogenic environment.
1. A superconducting device comprising:
at least one superconducting element having a first coefficient of thermal expansion, wherein the at least one superconducting element is formed in a first plane, wherein the at least one superconducting element has a first dimension in a first direction and a second dimension in a second direction, wherein the first dimension represents a length of the at least one superconducting element and the second dimension represents a width of the at least one superconducting element, and wherein the at least one superconducting element is formed on a dielectric layer having a second coefficient of thermal expansion, and wherein the first coefficient of thermal expansion is different from the second coefficient of thermal expansion causing a strain mismatch between the at least one superconducting element and the dielectric layer at temperatures below 77 K; and
at least one dummy element configured to lower stress at an interface between the at least one superconducting element and the dielectric layer, wherein the at least one dummy element is configured to be an electrically passive element, wherein the at least one dummy element is formed in the first plane along the length of the at least one superconducting element, and wherein the at least one dummy element includes a plurality of nubs, and wherein each of the plurality of nubs is configured to protrude from the at least one superconducting element.
2. The superconducting device of claim 1 , wherein the cryogenic environment corresponds to a temperature in a range of 4 Kelvin to 77 Kelvin.
3. The superconducting device of claim 1 , wherein the at least one superconducting element comprises niobium.
4. The superconducting device of claim 3 , wherein the at least one dummy element comprises at least one of niobium, tungsten, molybdenum, tantalum, chromium, or indium.
5. The superconducting device of claim 1 , wherein the at least one dummy element further comprises at least one via, and wherein the at least one superconducting element is a wire formed in a plane and the at least one via extends in a direction that is orthogonal to the plane.
6. The superconducting device of claim 5 , wherein the at least one via is further configured to reduce dishing of the plane during a chemical-mechanical polishing step.
7. A superconducting device comprising:
at least one superconducting wire having a first coefficient of thermal expansion, wherein the at least one superconducting wire is formed on a dielectric layer having a second coefficient of thermal expansion, and wherein the first coefficient of thermal expansion is different from the second coefficient of thermal expansion causing a strain mismatch between the at least one superconducting wire and the dielectric layer when the superconducting device is operating in a cryogenic environment; and
at least one dummy element comprising a plurality of nubs, wherein the at least one dummy element is configured to be an electrically passive element, wherein each of the plurality of nubs is formed along the at least one superconducting wire, wherein each of the plurality of nubs is configured to lower stress at an interface between the at least one superconducting wire and the dielectric layer at temperatures below 77K, and wherein at least a subset of the plurality of the nubs includes at least one short-segment branch configured to increase a surface area between the at least one superconducting wire and the at least one dummy element.
8. The superconducting device of claim 7 , wherein the cryogenic environment corresponds to a temperature in a range of 4 Kelvin to 77 Kelvin.
9. The superconducting device of claim 7 , wherein the at least one superconducting wire comprises niobium.
10. The superconducting device of claim 9 , wherein the at least one dummy element comprises at least one of niobium, tungsten, molybdenum, tantalum, chromium, or indium.
11. The superconducting device of claim 7 , wherein the at least one dummy element further comprises at least one via, and wherein the at least one superconducting wire is formed in a plane and the at least one via extends in a direction that is orthogonal to the plane.
12. The superconducting device of claim 11 , wherein the at least one via is further configured to reduce dishing of the plane during a chemical-mechanical polishing step.
13. A superconducting device comprising:
at least one superconducting wire having a first coefficient of thermal expansion, wherein the at least one superconducting wire is formed on a dielectric layer having a second coefficient of thermal expansion, and wherein the first coefficient of thermal expansion is different from the second coefficient of thermal expansion causing a strain mismatch between the at least one superconducting wire and the dielectric layer at temperatures below 77K; and
at least one dummy element comprising a plurality of nubs and at least one via, wherein each of the plurality of nubs is formed along the at least one superconducting wire, wherein each of the plurality of nubs is configured to lower stress at an interface between the at least one superconducting wire and the dielectric layer, wherein the at least one dummy element is configured to be an electrically passive element, and wherein the at least one dummy element further comprises at least one via, and wherein the at least one superconducting wire is formed in a plane and the at least one via extends in a direction that is orthogonal to the plane.
14. The superconducting device of claim 13 , wherein the cryogenic environment corresponds to a temperature in a range of 4 Kelvin to 77 Kelvin.
15. The superconducting device of claim 13 , wherein the at least one superconducting wire comprises niobium.
16. The superconducting device of claim 15 , wherein the at least one dummy element comprises at least one of niobium, tungsten, molybdenum, tantalum, chromium, or indium.
17. The superconducting device of claim 13 , wherein the at least one via is further configured to reduce dishing of the plane during a chemical-mechanical polishing step.