# US 2021/0242391 A1 · Multiple step edge fabrication > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0242391 A1 - Document ID: US20210242391A1 - Status: Published application - Kind: A1 - Application number: 17/262,981 - Filed: 2019-10-18 - Published: 2021-08-05 - Earliest claimed: 2018-10-19 - Assignees: Commonwealth Scientific and Industrial Research Organisation - Applicants: Commonwealth Scientific and Industrial Research Organisation - Inventors: Jeina Lazar; Wendy Purches; Emma Mitchell; Chris Lewis - Web page: https://patentgrep.com/patent/US20210242391A1 ## CPC - H10N 60/0912: {of Josephson-effect devices} - G01R 33/0354: {SQUIDS} - H10N 60/0884: {Treatment of superconductor layers by irradiation, e.g. ion-beam, electron-beam, laser beam or X-rays} - H10N 60/0941: {comprising high-Tc ceramic materials} - H10N 60/12: Josephson-effect devices - H10N 60/124: {comprising high-Tc ceramic materials} - H10N 69/00: Integrated devices, or assemblies of multiple devices, comprising at least one superconducting element covered by group H10N60/00 - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract This disclosure relates to fabrication of step edges to fabricate Josephson junctions. A method comprises forming a layer of resist over the surface. The layer of resist comprises openings to expose a selected area of the surface, thereby forming two walls in the layer of resist on a perimeter of the selected area. The resist and the substrate are exposed to an ion beam, thereby etching the resist and the exposed areas of the surface. While exposing the resist and the substrate to the ion beam, the substrate is gradually rotated about an axis normal to the surface to thereby form two step edges at the respective two walls. Further, superconducting material is deposited onto the substrate in a meandering shape to form a path that crosses the two step edges multiple times and to form a Josephson junction each time the path crosses the step edges. ## Claims ### Claim 1 A method of forming multiple step edges in a surface of a crystalline substrate, the method comprising: forming a layer of resist over the surface, the layer of resist comprising openings to expose a selected area of the surface, thereby forming a first wall and a second wall in the layer of resist on a perimeter of the selected area; and exposing the resist and the substrate to an ion beam, thereby etching the resist and the exposed areas of the surface to thereby create an upper level outside the selected area and a lower level within the selected area of the surface; while exposing the resist and the substrate to the ion beam, gradually rotating the substrate about an axis normal to the surface to thereby form a first step edge at the first wall and a second step edge at the second wall; and depositing superconducting material onto the substrate in a meandering shape to form a path that crosses the first and second step edges multiple times, to form multiple Josephson junctions comprising at least one Josephson junction each time the path crosses one of the first and second step edges, wherein the path comprises multiple connections on the lower level, each connection connecting one of the multiple Josephson junctions on the first step edge to one of the multiple Josephson junction on the second step edge to thereby form the meandering shape. ### Claim 2 (depends on 1) The method of claim 1, wherein at least four junctions are formed and the four junctions are connected in series by the path. ### Claim 3 (depends on 2) The method of claim 2, wherein at least eight junctions are formed. ### Claim 4 (depends on 1) The method of claim 1, wherein the two walls are substantially parallel and opposing each other. ### Claim 5 (depends on 1) The method of claim 1, wherein each of the multiple step edges defines an upper level and a lower level and the superconducting material is deposited to form a first path section that crosses one of the two step edges from the upper level to the lower level; a second path section that crosses the same one of the two step edges from the lower level to the upper level; and a first connection on the lower level that connects the first path section to the second path section without reaching the upper level. ### Claim 6 (depends on 5) The method of claim 5, wherein the first connection is parallel to the one of the two step edges. ### Claim 7 (depends on 5) The method of claim 5, wherein the first path section, the second path section and the first connection form a first loop and material is deposited to form a second connection to connect the first loop to a second loop deposited on a different one of the two step edges. ### Claim 8 (depends on 1) The method of claim 1, wherein the superconducting material is deposited onto the substrate to form a loop comprising two Josephson junctions each time the path crosses one of the two step edges. ### Claim 9 (depends on 1) The method of claim 1, wherein the superconducting material is deposited onto the substrate to form an array comprising more than two Josephson junctions each time the path crosses one of the two step edges. ### Claim 10 (depends on 1) The method of claim 1, wherein gradually rotating the substrate comprises continuously rotating the substrate. ### Claim 11 (depends on 10) The method of claim 10, wherein continuously rotating the substrate comprises rotating the substrate at a constant rotation rate. ### Claim 12 (depends on 11) The method of claim 11, wherein the rotation rate is greater than one rotation during exposing the resist and the substrate to the ion beam. ### Claim 13 (depends on 12) The method of claim 12, wherein the rotation rate is more than 1 rotation per minute. ### Claim 14 (depends on 13) The method of claim 13, wherein the rotation rate is more than 10 rotations per minute. ### Claim 15 (depends on 1) The method of claim 1, wherein the two walls are opposing each other on either side of the exposed area and a distance between the two opposing walls is less than 20 μm. ### Claim 16 (depends on 1) The method of claim 1, wherein junction parameters of the Josephson junctions are identical within manufacturing variations. ### Claim 17 (depends on 1) The method of claim 1, wherein the selected area comprises multiple shapes each having two walls forming two respective step edges and the path crosses the two step edges of each shape multiple times. ### Claim 18 (depends on 17) The method of claim 17, wherein the shapes are rectangular and arranged side by side such that the path crosses the two walls of all of the shapes in a straight line. ### Claim 19 A device comprising: a first wall and a second wall in a surface of a crystalline substrate on a perimeter of an etched area; a first step edge at the first wall and a second step edge at the second wall; a meandering path of superconducting material deposited onto the substrate, the path crossing the first and second step edges multiple times; and multiple Josephson junctions comprising at least one Josephson junction formed within the path each time the path crosses one of the first and second step edges, wherein the path comprises multiple connections on the lower level, each connection connecting one of the multiple Josephson junctions on the first step edge to one of the multiple Josephson junction on the second step edge to thereby form the meandering shape. ### Claim 20 (depends on 19) The device of claim 19, wherein the device comprises at least four Josephson junctions connected in series formed within the path. ### Claim 21 (depends on 20) The device of claim 20, wherein the device comprises at least eight Josephson junctions. ### Claim 22 (depends on 19) The device of claim 19, wherein a distance between the two step edges is less than 20 μm.