# US 12,224,082 B2 · Stress engineered microspring for cryogenic superconducting circuits > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,224,082 B2 - Document ID: US12224082B2 - Status: Granted - Kind: B2 - Application number: 18/107,575 - Filed: 2023-02-09 - Published: 2024-08-15 - Granted: 2025-02-11 - Earliest claimed: 2023-02-09 - Assignees: Xerox Corporation - Applicants: Palo Alto Research Center Incorporated - Inventors: Qian Wang; Christopher L. Chua; Yu Wang; Eugene M. Chow - Web page: https://patentgrep.com/patent/US12224082B2 ## CPC - H01B 12/02: characterised by their form - H10N 60/01: Manufacture or treatment - H10N 60/80: Constructional details - H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K}) - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract A microspring includes a film stack having a base disposed on a build plane and a spring member extending from the base. The film stack includes a compressive layer, a substantially stress-free layer, and a tensile layer. The film stack is formed of one or more materials that become superconducting below 140 K. A stress gradient in the film stack causes the spring member to curl away from the build plane of the base. ## Claims ### Claim 1 A structure, comprising: a microspring comprising a film stack having a base disposed on a build surface and a spring member extending from the base; and the film stack comprising a compressive layer, a substantially stress-free layer, and a tensile layer, the film stack formed of one or more materials that become superconducting below 140 K; wherein a stress gradient in the film stack causes the spring member to curl away from the build surface of the base. ### Claim 2 (depends on 1) The structure of claim 1, wherein the substantially stress-free layer is sandwiched between the compressive layer and the tensile layer. ### Claim 3 (depends on 1) The structure of claim 1, wherein the substantially stress-free layer is above the compressive layer and the tensile layer relative to the build surface. ### Claim 4 (depends on 1) The structure of claim 1, wherein the substantially stress-free layer is below the compressive layer and the tensile layer relative to the build surface. ### Claim 5 (depends on 1) The structure of claim 1, wherein the compressive layer, the substantially stress-free layer, and the tensile layer are formed of Nb. ### Claim 6 (depends on 1) The structure of claim 1, comprising a top Au layer and a bottom Au layer, wherein the film stack is disposed between the top and bottom Au layers. ### Claim 7 (depends on 1) The structure of claim 1, wherein a lift height by which the spring member curls away from the build surface of the base is a controlled by a thickness of the substantially stress-free layer. ### Claim 8 (depends on 1) The structure of claim 1, wherein the substantially stress-free layer has a thickness greater than a thickness of the compressive layer and a thickness of the tensile layer. ### Claim 9 (depends on 8) The structure of claim 8, wherein the substantially stress-free layer has a higher critical temperature than the compressive and tensile layers. ### Claim 10 (depends on 1) The structure of claim 1, wherein the microspring is disposed on a prefabricated cryogenic electronic device or a superconductive quantum computing device. ### Claim 11 A structure, comprising: a microspring disposed on a build surface and comprising a film stack with a base and a spring member extending from the base; and the film stack comprising, in order from the build surface: a compressive layer having a first thickness; a substantially stress-free layer having a second thickness; and a tensile layer having a third thickness, wherein the second thickness is greater than the first and third thicknesses; wherein a stress gradient in the film stack causes the spring member to curl away from the build surface of the base. ### Claim 12 (depends on 11) The structure of claim 11, wherein the compressive layer, the substantially stress-free layer, and the tensile layer are formed of Nb. ### Claim 13 (depends on 11) The structure of claim 11, wherein the substantially stress-free layer has a higher critical temperature than the compressive and tensile layers. ### Claim 14 (depends on 11) The structure of claim 11, wherein the microspring is disposed on a prefabricated cryogenic electronic device or a superconductive quantum computing device. ### Claim 15 (depends on 11) The structure of claim 11, comprising a top metal layer and a bottom metal layer, wherein the film stack is disposed between the top and bottom metal layers, wherein the top and bottom metal layers comprise gold (Au). ### Claim 16 A method of forming a microspring structure, comprising: depositing a sacrificial release layer over a substrate, the sacrificial release layer defining a build surface; depositing a film stack over the sacrificial release layer, the film stack comprising a compressive layer proximate the substrate, a tensile layer spaced from the substrate, and a substantially stress-free layer disposed between the compressive and tensile layers, the film stack formed of one or more materials that become superconducting below 140 K; patterning the film stack to define the microspring structure on the build surface, the microspring structure comprising a base and a spring member extending from the base; and removing a portion of the sacrificial release layer located under the spring member, such that stress within the film stack causes the spring member to curl out of the build surface. ### Claim 17 (depends on 16) The method of claim 16, wherein the compressive layer, the substantially stress-free layer, and the tensile layer are formed of Nb. ### Claim 18 (depends on 16) The method of claim 16, further comprising patterning a photoresist layer over an edge of the base and a portion of the spring member near the base, wherein a profile of the spring member is controlled by: selection of a size of the portion of the spring member near the base that is covered by the photoresist layer; and selection of an overlap between the sacrificial release and the spring member away from the base. ### Claim 19 (depends on 16) The method of claim 16, wherein the depositing of the film stack comprises varying a deposition pressure in a sputtering chamber to induce intrinsic compressive, neutral, and tensile stresses respectively in the compressive layer, the substrate, the tensile layer, and the substantially stress-free layer. ### Claim 20 (depends on 16) The method of claim 16, wherein the substantially stress-free layer has a higher critical temperature than the compressive and tensile layers.