Superconducting circuit, superconducting circuit fabrication method, and system

Abstract

The application relates to a superconducting circuit, a superconducting circuit preparation method and a system, and relates to the technical field of micro-nano processing. The superconducting circuit comprises a peripheral circuit, a junction region circuit, a first air bridge and a second air bridge; the junction region circuit comprises a first lead wire and a second lead wire; the first lead wire and the second lead wire cross each other, and a Josephson junction is formed at the crossing of the first lead wire and the second lead wire; the first lead wire and the peripheral circuit are connected through the first air bridge; and the second lead wire and the peripheral circuit are connected through the second air bridge.

Description

Technical Field

[0001] This application relates to the field of micro-nano fabrication technology, and in particular to a superconducting circuit, a method for fabricating a superconducting circuit, and a system thereof. Background Technology

[0002] Josephson junctions can be fabricated using specially designed photoresist structures.

[0003] In related technologies, a Dolan bridge photoresist structure pattern with undercut can be made on a double-layer electron beam photoresist on the substrate surface using electron beam exposure. Then, a Josephson junction is prepared by a double-tilt evaporation method, which first deposits a superconducting metal film at an angle, then oxidizes it to form an insulating layer, and then vertically evaporates the superconducting metal film.

[0004] Then, in the above-mentioned method for preparing Josephson junctions, an extra Josephson junction (also known as a parasitic junction) will be introduced into the prepared superconducting circuit, thereby affecting the coherence of the superconducting circuit. Summary of the Invention

[0005] This application provides a superconducting circuit, a method for fabricating a superconducting circuit, and a system that can improve the circuit performance of the superconducting circuit. The technical solution is as follows.

[0006] On the one hand, a superconducting circuit is provided, the superconducting circuit including a peripheral circuit, a junction circuit, a first air bridge and a second air bridge;

[0007] The junction circuit includes a first lead and a second lead; the first lead and the second lead intersect each other, and the intersection of the first lead and the second lead forms a Josephson junction;

[0008] The first lead is connected to the peripheral circuit via the first air bridge;

[0009] The second lead is connected to the peripheral circuit via the second air bridge.

[0010] On the one hand, a method for fabricating a superconducting circuit is provided, the method comprising:

[0011] Fabricating the peripheral circuitry of a superconducting circuit on a substrate;

[0012] A junction circuit is fabricated on the substrate; the junction circuit includes a first lead and a second lead; the first lead and the second lead intersect each other, and the intersection of the first lead and the second lead forms a Josephson junction;

[0013] A first air bridge is prepared between the first lead and the peripheral circuit, and a second air bridge is prepared between the second lead and the peripheral circuit.

[0014] On another front, a Josephson junction fabrication system is provided, the system comprising: a coating machine, a photolithography machine, a vapor deposition machine, an etching machine, and a cleaning machine;

[0015] The coating machine, the photolithography machine, the evaporation machine, and the cleaning machine are used to fabricate the peripheral circuits of the superconducting circuit on the substrate.

[0016] The coating machine, the photolithography machine, the evaporation machine, and the cleaning machine are used to fabricate junction circuits on the substrate; the junction circuits include a first lead and a second lead; the first lead and the second lead intersect each other, and the intersection of the first lead and the second lead forms a Josephson junction;

[0017] The coating machine, the photolithography machine, the vapor deposition machine, and the cleaning machine are used to prepare a first air bridge between the first lead and the peripheral circuit, and a second air bridge between the second lead and the peripheral circuit.

[0018] In one possible implementation, a photoresist coating subsystem is used to coat a substrate containing peripheral circuitry and junction circuitry.

[0019] A photolithography subsystem and a cleaning subsystem are used to prepare an arched photoresist structure, the arched photoresist structure being located between a first region on the peripheral circuit and a second region on the first lead, and between a third region on the peripheral circuit and a fourth region on the second lead, wherein the photoresist corresponding to the first and second regions and the photoresist corresponding to the third and fourth regions are removed.

[0020] A vapor deposition subsystem for preparing metal films on photoresist;

[0021] A coating subsystem, a photolithography subsystem, an etching subsystem, and a cleaning subsystem are used to remove the metal film layer from the metal film layer, except between the first region and the second region, and between the third region and the fourth region, to obtain a first air bridge and a second air bridge.

[0022] The cleaning subsystem is used to remove residual photoresist from the substrate.

[0023] In one possible implementation, a photolithography subsystem and a cleaning subsystem are used to perform exposure and development processes on the photoresist in the first and second regions, as well as the photoresist in the third and fourth regions, to remove the photoresist in the first and second regions and the photoresist in the third and fourth regions.

[0024] The superconducting circuit fabrication system also includes:

[0025] The reflow subsystem is used to perform reflow processing on the remaining photoresist on the substrate.

[0026] In one possible implementation, the reflow processing time is 2 to 4 minutes.

[0027] In one possible implementation, the reflux temperature is between 130 and 150 degrees Celsius.

[0028] In one possible implementation, the photolithography subsystem is used to expose the region of the photoresist on the substrate corresponding to the arched photoresist structure with a first exposure dose; and to expose the other regions of the photoresist on the substrate other than the arched photoresist structure with a second exposure dose; the second exposure dose is higher than the first exposure dose.

[0029] The cleaning subsystem is used to perform development processing on the exposed photoresist to remove photoresist from areas other than the arched photoresist structure.

[0030] In one possible implementation, the etching subsystem is also used to perform etching on the first region, the second region, the third region, and the fourth region before the evaporation subsystem prepares the metal film on the photoresist, in order to remove the oxide layers on the peripheral circuit corresponding to the first region and the third region, the oxide layer on the first lead corresponding to the second region, and the oxide layer on the second lead corresponding to the fourth region.

[0031] In one possible implementation, an etching subsystem is used to perform etching on areas of the metal film other than the areas corresponding to the first and second air bridges.

[0032] In one possible implementation, an etching subsystem is used to perform etching on the metal film layers at the edge locations of the first air bridge and the edge locations of the second air bridge.

[0033] The cleaning subsystem is used to perform cleaning processes on the photoresist on the substrate.

[0034] In one possible implementation, the metal film layer is made of the same material as the surrounding circuitry, or;

[0035] The material of the metal film layer is the same as the material of the junction circuit, or;

[0036] The material of the metal film layer is the same as that of the peripheral circuit and the junction circuit.

[0037] In another aspect, a chip is provided, the chip comprising: a substrate and a superconducting circuit located on the substrate;

[0038] The superconducting circuit includes a peripheral circuit, a junction circuit, a first air bridge, and a second air bridge.

[0039] The junction circuit includes a first lead and a second lead; the first lead and the second lead intersect each other, and the intersection of the first lead and the second lead forms a Josephson junction;

[0040] The first lead is connected to the peripheral circuit via the first air bridge;

[0041] The second lead is connected to the peripheral circuit via the second air bridge.

[0042] The beneficial effects of the technical solutions provided in this application include at least the following:

[0043] A superconducting circuit is provided that connects the Josephson junction and the peripheral circuit via an air bridge. Specifically, for the two leads that form the Josephson junction in a cross configuration, each is connected to the peripheral circuit of the superconducting circuit via an air bridge. Since the air bridge is not in contact with the substrate, the substrate at the location corresponding to the air bridge can be directly etched during the fabrication of the superconducting circuit, thereby avoiding damage to the substrate at the location corresponding to the air bridge due to etching and improving the circuit performance of the superconducting circuit.

[0044] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0045] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0046] Figure 1 This is a schematic diagram of a superconducting circuit according to an embodiment of this application;

[0047] Figure 2 This is a schematic diagram of another superconducting circuit involved in an embodiment of this application;

[0048] Figure 3 This is a schematic diagram of the structure of a superconducting circuit shown in an exemplary embodiment of this application;

[0049] Figure 4 This is a flowchart illustrating a method for fabricating a superconducting circuit according to an exemplary embodiment of this application;

[0050] Figure 5 This is a flowchart illustrating a method for fabricating a superconducting circuit according to an exemplary embodiment of this application;

[0051] Figure 6 This is a cross-sectional view of the Josephson junction involved in the embodiments of this application;

[0052] Figure 7This is a cross-sectional view of the arched photoresist structure involved in the embodiments of this application;

[0053] Figure 8 This is a cross-sectional view of the bridge structure involved in the embodiments of this application;

[0054] Figure 9 This is a cross-sectional view of the superconducting circuit involved in the embodiments of this application;

[0055] Figure 10 This is a cross-sectional view of the exposure area involved in the embodiments of this application;

[0056] Figure 11 This is a flowchart illustrating the fabrication process of a superconducting circuit according to an embodiment of this application;

[0057] Figure 12 This is a flowchart illustrating the fabrication process of another superconducting circuit involved in an embodiment of this application;

[0058] Figure 13 This is a schematic diagram of a product application scenario provided in one embodiment of this application;

[0059] Figure 14 This is a schematic diagram of a superconducting circuit fabrication system illustrated in an exemplary embodiment of this application. Detailed Implementation

[0060] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0061] Josephson junction: A sandwich-like structure composed of a superconducting layer, an insulating layer, and another superconducting layer stacked together, also known as a superconducting tunnel junction. A Josephson junction is generally a structure consisting of two superconductors sandwiched by a very thin barrier layer (thickness ≤ the coherence length of a Cooper pair), such as an S (Superconductor)-I (Semiconductor or Insulator)-S (Superconductor) structure, abbreviated as SIS. In a Josephson junction, superconducting electrons can tunnel from one side through the semiconductor or insulating film to the other side via the tunneling effect.

[0062] Parasitic junction: Other Josephson knots that are introduced during the preparation of Josephson knots.

[0063] Ion milling: using an ion beam of a specific direction to bombard the surface of a material to remove the oxide layer on the material surface.

[0064] Oblique evaporation / straight evaporation: Evaporation of a thin film by means of material that is not parallel to or parallel to the normal direction of the substrate.

[0065] Lift-off: The process in which the photoresist dissolves in the stripper solution, and the metal layer on the photoresist is also removed from the substrate.

[0066] Undercut: The pattern structure formed after photoresist is developed, where the upper opening size is smaller than the lower opening size.

[0067] The most common method for fabricating Josephson junctions is tilted deposition. This involves first fabricating the peripheral circuitry (also known as the large-scale circuit structure or bottom-layer large-scale circuit structure) using laser direct writing or ultraviolet exposure, including readout lines, resonant cavities, and capacitors. The linewidths of these circuits are typically on the order of several to tens of micrometers. Then, electron beam lithography is used to expose the undercut structure on electron beam photoresist. Because electron beam lithography has high resolution but is very slow, it is commonly used to expose Josephson junctions. Finally, the Josephson junction is fabricated through ion milling, positive aluminum plating, oxidation, and tilted aluminum plating. In the overlapping regions between positive and tilted plating, an oxide layer forms between the two thin films, creating a parasitic junction. Please refer to [reference needed]. Figure 1 It shows a schematic diagram of a superconducting circuit according to an embodiment of this application, such as... Figure 1 As shown, the dashed box 110 (that is, the overlapping part of metal layer 120 and metal layer 130) is a parasitic junction.

[0068] Please refer to Figure 2 It shows a schematic diagram of another superconducting circuit involved in an embodiment of this application. Figure 2 A Josephson knot preparation scheme was proposed to avoid the presence of parasitic knots, such as... Figure 2 As shown, a Josephson junction is first fabricated by the intersection of leads 201 and 202, but leads 201 and 202 do not contact the underlying large circuit. Then, regions 203 and 204 are ion-milled and then coated to connect the Josephson junction and the large circuit. However, this method will damage the substrate at the corresponding positions of regions 203 and 204.

[0069] To improve the circuit performance of superconducting circuits containing Josephson junctions, subsequent embodiments of this application provide a new superconducting circuit structure.

[0070] Please refer to Figure 3This illustrates a schematic diagram of a superconducting circuit according to an exemplary embodiment of this application. Figure 3 As shown, the superconducting circuit may include a peripheral circuit 310, a junction circuit 320, a first air bridge 330, and a second air bridge 340.

[0071] The junction circuit 320 includes a first lead 321 and a second lead 322; the first lead 321 and the second lead 322 intersect each other, and the intersection of the first lead 321 and the second lead 322 forms a Josephson junction 323.

[0072] The first lead 321 is connected to the peripheral circuit 310 via the first air bridge 330.

[0073] The second lead 322 is connected to the peripheral circuit 310 via the second air bridge 340.

[0074] An air bridge, also known as an air bridge, is a connection structure in micro / nano circuits. An air bridge comprises piers and supports. The piers are areas on the underlying circuit structure reserved for contact between the air bridge and the underlying circuit (corresponding to the peripheral circuit and the first and second leads in this embodiment). The supports are portions of the air bridge used for connection to the underlying circuit. The supports are suspended structures and do not contact the underlying circuit or the substrate.

[0075] The solution shown in this application provides a superconducting circuit that connects the Josephson junction and the peripheral circuit via an air bridge. Specifically, for the two leads that form the Josephson junction in a cross manner, each is connected to the peripheral circuit of the superconducting circuit via an air bridge. Since the air bridge is not in contact with the substrate, the substrate at the corresponding position of the air bridge can be directly etched during the fabrication of the superconducting circuit, thereby avoiding damage to the substrate at the corresponding position of the air bridge due to etching and improving the circuit performance of the superconducting circuit.

[0076] Based on the above Figure 3 In some embodiments of the solutions provided by the illustrated examples, the materials of the first air bridge and the second air bridge are the same as the materials of the peripheral circuit.

[0077] In this embodiment, the materials of the first and second air bridges can be the same as the materials of the peripheral circuits.

[0078] The material of the aforementioned peripheral circuit can be a non-superconducting metal. For example, the material of the aforementioned peripheral circuit can be tantalum metal, and correspondingly, the material of the first air bridge and the second air bridge is also tantalum metal.

[0079] Alternatively, the material of the aforementioned peripheral circuit can be a superconducting metal, such as aluminum. Correspondingly, the materials of the first air bridge and the second air bridge are also aluminum.

[0080] The above embodiments of this application are only illustrated by taking the material of the peripheral circuit as tantalum or aluminum as an example. In other embodiments, the materials of the peripheral circuit, the first air bridge and the second air bridge may also be other metals or alloys that constitute the circuit. The embodiments of this application do not limit this.

[0081] In this embodiment, the peripheral circuit, the first air bridge, and the second air bridge are made of the same material, which can ensure the consistency of circuit performance between the peripheral circuit and the air bridge, thereby ensuring the circuit performance of the superconducting circuit.

[0082] Based on the above Figure 3 In some embodiments of the solutions provided by the examples shown, the materials of the first air bridge and the second air bridge are the same as the materials of the junction circuit.

[0083] In the embodiments of this application, the materials of the first air bridge and the second air bridge can be the same as the materials of the junction circuit (that is, the first lead and the second lead).

[0084] The junction circuit can be made of superconducting metal, such as aluminum. Correspondingly, the first and second air bridges are also made of aluminum.

[0085] The above embodiments of this application are only illustrated by taking the material of the junction circuit as aluminum as an example. In other embodiments, the materials of the junction circuit, the first air bridge and the second air bridge can also be other superconducting metals or alloys. This application does not limit the materials used in the embodiments.

[0086] In some embodiments, when the materials of the first lead and the second lead in the junction circuit are different, the material of the first air bridge is the same as the material of the first lead, and the material of the second air bridge is the same as the material of the second lead; or, the materials of the first air bridge and the second air bridge are the same as the material of the first lead; or, the materials of the first air bridge and the second air bridge are the same as the material of the second lead.

[0087] In the embodiments of this application, the materials of the first lead and the second lead can be different superconducting materials. For example, the material of the first lead is aluminum and the material of the second lead is niobium. In this case, the material of the first air bridge is aluminum and the material of the second air bridge is niobium. Alternatively, the materials of the first air bridge and the second air bridge are both aluminum. Alternatively, the materials of the first air bridge and the second air bridge are both niobium.

[0088] In the embodiments of this application, the junction circuit, the first air bridge, and the second air bridge are made of the same material, which can ensure the consistency of circuit performance between the junction circuit and the air bridge, thereby ensuring the circuit performance of the superconducting circuit.

[0089] Based on the above Figure 3 In some embodiments of the solutions provided by the illustrated examples, the materials of the first air bridge and the second air bridge are the same as the materials of the peripheral circuit and the junction circuit.

[0090] In the embodiments of this application, the materials of the first air bridge and the second air bridge, the materials of the peripheral circuits, and the materials of the junction circuit (that is, the first lead and the second lead) can be the same.

[0091] The materials of the aforementioned peripheral circuits and junction circuits can be superconducting metals. For example, the materials of the aforementioned peripheral circuits and junction circuits can both be aluminum. Correspondingly, the materials of the first air bridge and the second air bridge are also aluminum.

[0092] The above embodiments of this application are only illustrated by taking the material of the peripheral circuit and the junction circuit as aluminum as an example. In other embodiments, the materials of the junction circuit, the peripheral circuit, the first air bridge and the second air bridge can also be other superconducting metals or alloys. The embodiments of this application do not limit this.

[0093] In this embodiment, the junction circuit, peripheral circuit, first air bridge and second air bridge are made of the same material, which can ensure the consistency of circuit performance between the junction circuit, air bridge and peripheral circuit, thereby ensuring the circuit performance of the superconducting circuit.

[0094] Based on the solutions shown in any one or more of the above embodiments of this application, please refer to Figure 4 It shows a flowchart of a method for fabricating a superconducting circuit according to an exemplary embodiment of this application, as follows. Figure 4 As shown, the method may include steps 410, 420 and 430.

[0095] Step 410: Fabricate the peripheral circuit of the superconducting circuit on the substrate.

[0096] In the embodiments of this application, the peripheral circuit can be prepared by evaporating a metal film layer on the substrate and spin-coating photoresist, and then by photolithography, development and etching.

[0097] For example, a metal film layer of the material corresponding to the peripheral circuit can be deposited on the substrate first, and then a layer of photoresist can be spin-coated on the metal film layer. The pattern of the peripheral circuit can be exposed on the photoresist by photolithography. After exposure, the product is cleaned with developer to remove the photoresist outside the area corresponding to the peripheral circuit. Then, etching operation is performed by ion milling or other methods to remove the metal film layer other than the peripheral circuit, leaving the metal film layer of the peripheral circuit on the substrate.

[0098] Step 420: Fabricate a junction circuit on the substrate; the junction circuit includes a first lead and a second lead; the first lead and the second lead intersect each other, and the intersection of the first lead and the second lead constitutes a Josephson junction.

[0099] In the embodiments of this application, photoresist can be spin-coated on a substrate on which the peripheral circuit is fabricated, and an undercut structure can be exposed on the electron beam photoresist by electron beam exposure. The first lead and the second lead can be fabricated by positive plating and tilted evaporation.

[0100] In some embodiments, the positions of the peripheral circuit, the first lead, and the second lead can be similar. Figure 2 As shown.

[0101] Step 430: Prepare a first air bridge between the first lead and the peripheral circuit, and a second air bridge between the second lead and the peripheral circuit.

[0102] In the embodiments of this application, after fabricating the peripheral circuit, the first lead, and the second lead, a first air bridge for connecting the peripheral circuit and the first lead, and a second air bridge for connecting the peripheral circuit and the second lead, can be fabricated.

[0103] In some embodiments, if the first air bridge and the second air bridge are made of different materials, the first air bridge and the second air bridge can be prepared by different steps.

[0104] For example, a first air bridge between the first lead and the peripheral circuit can be prepared first, and then a second air bridge between the second lead and the peripheral circuit can be prepared after the first air bridge is prepared.

[0105] The embodiment of this application provides a fabrication scheme for a superconducting circuit that connects the Josephson junction and the peripheral circuit via an air bridge. Specifically, for the two leads that form the Josephson junction in a cross manner, an air bridge is fabricated to connect to the peripheral circuit of the superconducting circuit. Since the air bridge is not in contact with the substrate, the substrate at the corresponding position of the air bridge can be directly etched during the fabrication process of the superconducting circuit, thereby avoiding damage to the substrate at the corresponding position of the air bridge due to etching and improving the circuit performance of the superconducting circuit.

[0106] Based on the solutions shown in any one or more of the above embodiments of this application, please refer to Figure 5 It shows a flowchart of a method for fabricating a superconducting circuit according to an exemplary embodiment of this application, as follows. Figure 5 As shown, step 430 can be implemented as: step 430a, step 430b, step 430c, step 430d and step 430e.

[0107] Step 430a: Apply photoresist to the substrate containing the peripheral circuit and the junction circuit.

[0108] In the embodiments of this application, a photoresist can be spin-coated onto a substrate on which peripheral circuits and junction circuits are fabricated by a spin coating machine.

[0109] Step 430b: Prepare an arched photoresist structure, which is located between a first region on the peripheral circuit and a second region on the first lead, and between a third region on the peripheral circuit and a fourth region on the second lead. The photoresist corresponding to the first and second regions, as well as the photoresist corresponding to the third and fourth regions, is removed.

[0110] In this embodiment of the application, an arched photoresist structure can be fabricated on the photoresist between the peripheral circuit, the first lead, and the second lead, so that the metal film layer between the horizontal frame peripheral circuit and the first lead, as well as the peripheral circuit and the second lead, can be supported during the subsequent fabrication of the air bridge.

[0111] In some embodiments, if the first air bridge and the second air bridge are made of different materials, the fabrication process of the arched photoresist structure in step 430b will be performed in the fabrication processes corresponding to the two air bridges respectively. Furthermore, in the fabrication processes of different air bridges, the arched photoresist structure is fabricated at the location of the current air bridge. Alternatively, the arched photoresist structures at different locations involved in step 430b are fabricated in the fabrication processes of different air bridges.

[0112] For example, in the fabrication process of the first air bridge, after coating photoresist on the substrate containing the peripheral circuit and the junction circuit, an arched photoresist structure is fabricated between the first region on the peripheral circuit and the second region on the first lead; in the fabrication process of the second air bridge, after coating photoresist on the substrate containing the peripheral circuit and the junction circuit, an arched photoresist structure is fabricated between the third region on the peripheral circuit and the fourth region on the second lead.

[0113] Step 430c: Prepare a metal film layer on the photoresist.

[0114] In the embodiments of this application, a metal film layer can be deposited on the photoresist on which the arched photoresist structure has been prepared using an evaporation machine.

[0115] In some embodiments, the thickness of the metal film can be selected from 100 to 400 nm.

[0116] In some embodiments, if the first air bridge and the second air bridge are made of different materials, the metal film preparation process in step 430c will be performed in the preparation processes corresponding to the two air bridges respectively, and in the preparation processes of different air bridges, a metal film corresponding to the material of the current air bridge will be prepared. For example, in the preparation process of the first air bridge, after preparing the arched photoresist structure, a metal film of the material corresponding to the first air bridge will be prepared on the photoresist; in the preparation process of the second air bridge, after preparing the arched photoresist structure, a metal film of the material corresponding to the second air bridge will be prepared on the photoresist.

[0117] Step 430d: Remove the metal film layers except between the first and second regions, and between the third and fourth regions, to obtain the first air bridge and the second air bridge.

[0118] In this embodiment, the metal film layer, excluding the first air bridge and the second air bridge, can be removed by etching, peeling, or other methods, while retaining the first air bridge and the second air bridge.

[0119] In some embodiments, if the first air bridge and the second air bridge are made of different materials, step 430d will be performed in the preparation process corresponding to each of the two air bridges. That is, in the preparation process of each air bridge, the metal film layer other than the corresponding air bridge needs to be removed.

[0120] For example, in the preparation process of the first air bridge, after preparing the metal film layer corresponding to the material of the first air bridge, the metal film layer except for the metal film layer between the first region and the second region can be removed to obtain the first air bridge; correspondingly, in the preparation process of the second air bridge, after preparing the metal film layer corresponding to the material of the second air bridge, the metal film layer except for the metal film layer between the third region and the fourth region can be removed to obtain the second air bridge.

[0121] Step 430e: Remove residual photoresist from the substrate.

[0122] In this embodiment, the photoresist on the substrate can be cleaned using a cleaning machine to obtain a superconducting circuit with peripheral circuits, junction circuits, a first air bridge, and a second air bridge.

[0123] The scheme shown in the embodiments of this application firstly uses photoresist to prepare an arched photoresist structure between the peripheral circuit, the first lead, and the second lead. Then, a metal film layer is prepared. The metal film layer on the arched photoresist structure can connect the peripheral circuit to the first lead and the peripheral circuit to the second lead. Then, the metal film layer outside the connection portion between the peripheral circuit and the first lead and the connection portion between the peripheral circuit and the second lead is removed. Finally, the residual photoresist is cleaned, thus preparing the first air bridge and the second air bridge. This provides an achievable scheme for connecting the peripheral circuit to the first lead and the second lead respectively.

[0124] Based on the solutions shown in any one or more embodiments of the above embodiments of this application, in some embodiments, step 430b can be implemented as the following steps:

[0125] An exposure and development process is performed on the photoresist in the first and second regions, as well as the photoresist in the third and fourth regions, to remove the photoresist in the first and second regions and the photoresist in the third and fourth regions.

[0126] The remaining photoresist on the substrate is reflowed.

[0127] In this embodiment, the photoresist in the first and second regions, as well as the photoresist in the third and fourth regions, is first exposed using a photolithography machine. Then, the exposed product is placed in a developer solution for cleaning to remove the photoresist in the first and second regions, as well as the photoresist in the third and fourth regions, exposing the circuit portions of the first, second, third, and fourth regions. Then, the product is reflowed to form an arched photoresist structure between the peripheral circuit and the first lead, and between the peripheral circuit and the second lead.

[0128] In some embodiments, if the first air bridge and the second air bridge are made of different materials, in the fabrication process of the first air bridge, after coating photoresist on the substrate containing the peripheral circuit and the junction circuit, exposure and development processing is performed on the photoresist of the first region and the second region to remove the photoresist of the first region and the second region; in the fabrication process of the second air bridge, after coating photoresist on the substrate containing the peripheral circuit and the junction circuit, exposure and development processing is performed on the photoresist of the third region and the fourth region to remove the photoresist of the third region and the fourth region.

[0129] By performing photolithography and development on the bridge support area and then reflowing the process, an arched photoresist structure between the peripheral circuit and the first lead, and between the peripheral circuit and the second lead, can be fabricated. This process requires a smaller area to be exposed and developed, which can save photolithography and development time.

[0130] Based on the solutions shown in any one or more embodiments of the above embodiments of this application, in some embodiments, the reflow processing time is 2 to 4 minutes.

[0131] In some embodiments, the reflow processing time can be 3 minutes, or other times, such as 2 minutes, 2.5 minutes, 3.5 minutes, or 4 minutes, etc.

[0132] The solution shown in the embodiments of this application uses a reflow processing time of 2 to 4 minutes, which can keep the reflow processing time within a suitable range. This ensures the efficiency of the reflow processing while ensuring the fabrication of an air bridge with a suitable shape, thereby balancing the structural strength and fabrication efficiency of the air bridge.

[0133] Based on the solutions shown in any one or more embodiments of the above-described embodiments of this application, in some embodiments, the temperature of the reflux treatment is 130 degrees Celsius to 150 degrees Celsius.

[0134] In some embodiments, the temperature of the reflux process can be 140 degrees Celsius, or other temperatures, such as 130 degrees Celsius, 135 degrees Celsius, 145 degrees Celsius, or 150 degrees Celsius, etc.

[0135] By using the solution shown in the embodiments of this application, a reflow temperature of 130 degrees Celsius to 150 degrees Celsius can be maintained within a suitable range, ensuring that an air bridge of suitable shape can be obtained during the reflow process, thereby ensuring the structural strength of the air bridge.

[0136] Based on the solutions shown in any one or more embodiments of the above embodiments of this application, in some embodiments, step 430b can be implemented as the following steps:

[0137] Exposure is performed on the region of the photoresist on the substrate that corresponds to the arched photoresist structure using the first exposure dose.

[0138] Exposure is performed on the photoresist on the substrate using a second exposure dose, except for the arched photoresist structure; the second exposure dose is higher than the first exposure dose.

[0139] The exposed photoresist is developed to remove photoresist from areas other than the arched photoresist structure.

[0140] In this embodiment, the arched photoresist structure can be prepared by grayscale exposure. Specifically, during the photolithography process, the higher the exposure dose of the photoresist, the easier it is for the photoresist to be dissolved by the developer. Conversely, the lower the exposure dose, the less easily the photoresist is dissolved by the developer. For the part of the photoresist that needs to be retained (including the location of the arched photoresist structure), exposure is performed with a lower exposure dose. For the part that needs to be removed, exposure is performed with a higher exposure dose. In this way, during the development process, the photoresist that needs to be removed can be dissolved and removed, while the part corresponding to the arched photoresist structure will be retained.

[0141] Gray-scale lithography, a technique in photolithography, is a method of directly creating multi-level or continuous three-dimensional structures in a single lithography step by adjusting the exposure dose. Compared to traditional binary lithography (which only has two states: "exposed" or "unexposed"), gray-scale lithography can directly achieve stepped or gradient three-dimensional morphologies in the photoresist, thereby simplifying the process, reducing costs, and improving the manufacturing efficiency of complex structures.

[0142] Grayscale exposure can include the following two processes:

[0143] 1) Exposure dose control: Depending on the different thicknesses of photoresist required in different areas, the exposure dose can be controlled in the following ways:

[0144] ① Halftone Mask: The mask is designed with areas of different transmittance (such as tiny holes or stripes of different densities) so that light creates an intensity gradient distribution behind the mask.

[0145] ② Dosage modulation in direct-write lithography (such as electron beam or laser direct writing): directly controlling the change of writing energy to achieve different exposure depths in different areas.

[0146] ③ Multiple exposure stacking: By adjusting the mask position and dosage multiple times, different exposure amounts are accumulated in the photoresist.

[0147] 2) Development: During the development process, the solubility of photoresist changes non-linearly with different exposure doses (e.g., in positive photoresist, areas with higher exposure doses dissolve faster), eventually forming a highly gradient structure.

[0148] The scheme shown in the embodiments of this application allows for the fabrication of an arched photoresist structure between the peripheral circuit and the first lead, and between the peripheral circuit and the second lead, by exposing and developing the photoresist using grayscale exposure. This process only requires the photolithography and development steps, which simplifies the process flow and improves the fabrication efficiency of the arched photoresist structure.

[0149] In some embodiments, if the first air bridge and the second air bridge are made of different materials, during the fabrication process of different air bridges, the region of the arched photoresist structure corresponding to the current air bridge is exposed using a first exposure dose, and other regions are exposed using a second exposure dose. After the development process is performed, the arched photoresist structure at the location of the current air bridge can be obtained.

[0150] Based on the solutions shown in any one or more embodiments of the above embodiments of this application, in some embodiments, before step 430c above, the following steps are further included:

[0151] Etching is performed on the first region, the second region, the third region, and the fourth region to remove the oxide layers on the peripheral circuit corresponding to the first region and the third region, the oxide layer on the first lead corresponding to the second region, and the oxide layer on the second lead corresponding to the fourth region.

[0152] In this embodiment of the application, after the peripheral circuit and junction circuit are fabricated, and before step 430c above, the product may be exposed to air for a long time. At this time, the surface of the peripheral circuit and junction circuit may be oxidized, thereby forming an oxide layer. The oxide layer is also insulating. If step 430c is performed directly, it will affect the conductivity between the peripheral circuit and junction circuit and the air bridge, thereby affecting the circuit performance of the superconducting circuit.

[0153] In this embodiment of the application, before performing step 430c, an etching machine can be used to perform an etching operation on the product to remove the oxide layer on the surface of the metal layer in the first region, the second region, the third region, and the fourth region, thereby ensuring the conductivity between the peripheral circuit and the junction circuit and the air bridge, and thus ensuring the circuit performance of the superconducting circuit.

[0154] In some embodiments, if the first air bridge and the second air bridge are made of different materials, in the fabrication process of the first air bridge, after the metal film layer is prepared, the oxide layer corresponding to the first region on the peripheral circuit and the oxide layer corresponding to the second region on the first lead can be removed from the first region and the second region; in the fabrication process of the second air bridge, after the metal film layer is prepared, the oxide layer corresponding to the third region on the peripheral circuit and the oxide layer corresponding to the fourth region on the second lead can be removed from the third region and the fourth region.

[0155] Based on the solutions shown in any one or more embodiments of the above embodiments of this application, in some embodiments, step 430d can be implemented as follows:

[0156] Etching is performed on the areas of the metal film layer other than the areas corresponding to the first and second air bridges.

[0157] In some embodiments, a layer of photoresist can be spin-coated onto the product surface, and then photolithography and development are performed on the product to retain the photoresist on the upper surface of the areas corresponding to the first air bridge and the second air bridge, remove the upper photoresist in other areas, expose the metal film layer to be removed, and then remove the metal film layer in other areas except for the areas corresponding to the first air bridge and the second air bridge by etching.

[0158] In some embodiments, if the first air bridge and the second air bridge are made of different materials, in the fabrication process of the first air bridge, after the metal film layer is prepared, etching can be performed on the regions other than the region corresponding to the first air bridge; in the fabrication process of the second air bridge, after the metal film layer is prepared, etching can be performed on the regions other than the region corresponding to the second air bridge.

[0159] The solution shown in the embodiments of this application provides a method for removing the metal film layer other than the air bridge to be retained by etching, which can ensure the accuracy of air bridge fabrication.

[0160] Based on the solutions shown in any one or more embodiments of the above embodiments of this application, in some embodiments, step 430d can be implemented as follows:

[0161] Etching is performed on the metal film layers at the edges of the first and second air bridges; the photoresist on the substrate is cleaned.

[0162] In some embodiments, a layer of photoresist can be spin-coated onto the product surface, and then photolithography is performed on the product to remove the photoresist layer on the edge positions of the first air bridge and the second air bridge, exposing the edge positions of the first air bridge and the second air bridge. Then, the metal film layer on the edge positions of the first air bridge and the second air bridge is removed by etching. Afterward, the photoresist on the substrate is cleaned with a dissolving solution. Since the first air bridge and the second air bridge are connected to the peripheral circuit and the junction circuit at the bridge pier position, and the metal film layer of other parts is only attached to the photoresist, the other parts of the metal film layer can be peeled off together when cleaning the photoresist.

[0163] In some embodiments, if the first air bridge and the second air bridge are made of different materials, in the fabrication process of the first air bridge, the metal film layer at the edge of the first air bridge is etched and the photoresist on the substrate is cleaned; in the fabrication process of the second air bridge, the metal film layer at the edge of the second air bridge is etched and the photoresist on the substrate is cleaned.

[0164] The solution shown in this application embodiment only requires photolithography and development of the metal film layers at the edge positions of the first air bridge and the second air bridge, which can save photolithography and development time.

[0165] Based on the solutions shown in any one or more embodiments of the above embodiments of this application, in some embodiments, the material of the metal film layer is the same as the material of the peripheral circuit, or; the material of the metal film layer is the same as the material of the junction circuit, or; the material of the metal film layer is the same as the material of both the peripheral circuit and the junction circuit.

[0166] The idea behind the above embodiments of this application is to use an air bridge structure to connect the Josephson junction and the underlying large circuitry, which is called an air bridge bandage. This can avoid the formation of parasitic junctions and avoid damage to the substrate, thereby improving the performance of the superconducting circuitry.

[0167] In the fabrication of the air bridge bandage, the tantalum film on the substrate is first etched to form the underlying large circuit structure. Then, a Josephson junction is fabricated using an angled deposition method. The structure of the Josephson junction is as follows: Figure 2 As shown, there are no parasitic knots at this time. Please refer to [reference needed]. Figure 6 It shows a cross-sectional view of the Josephson junction involved in the embodiments of this application, such as Figure 6 As shown, structure 610 consists of two leads that form the Josephson junction. Figure 6 The two leads in the structure are non-parallel; they intersect at a certain point on the substrate to form a Josephson junction, the top view of which can be seen as follows. Figure 2 As shown.

[0168] Next, spin-coate the photoresist; a specific type of positive photoresist can be used. Then, expose the junction between the tantalum film and the Josephson junction. After exposure, develop with a specific type of developer for approximately 1 minute. Then, reflow the photoresist. The reflow temperature and time can be selected as 140℃ and 3 minutes, respectively. The purpose of reflow is to create an arched shape in the photoresist; please refer to [reference needed]. Figure 7 It shows a cross-sectional view of the arched photoresist structure involved in the embodiments of this application, such as Figure 7 As shown, the photoresist structure 710 is arched. It should be noted that... Figure 7 The image shows the photoresist structure between the tantalum film constituting the peripheral circuit and one of the leads.

[0169] The oxide layer at the junction of the tantalum film and the Josephson junction was then removed using ion milling, followed by metal deposition to form the bridge structure. Please refer to [reference needed]. Figure 8 It shows a cross-sectional view of the bridge structure involved in the embodiments of this application, such as... Figure 8As shown, the bridge structure is a metal structure 810. The metal membrane can be made of aluminum or tantalum, and the thickness can be selected from 100 to 400 nm.

[0170] After depositing the air bridges, remove the unwanted bridge areas using etching or stripping methods, and remove the photoresist from the sample. Please refer to [reference needed]. Figure 9 It shows a cross-sectional view of the superconducting circuit involved in the embodiments of this application, such as... Figure 9 As shown, the arched metal layer 910 serves as an air bridge. Because photoresist is spin-coated onto the sample during ion milling, only the tantalum film and the Josephson junction connection area are exposed, thus preventing damage to the substrate.

[0171] Alternatively, grayscale exposure can be used to create air bridges; please refer to [reference needed]. Figure 10 It shows a cross-sectional view of the exposure area involved in the embodiments of this application, such as Figure 10 As shown in section (a), the exposure dose of each area is controlled during the exposure process, and the parts that need to be removed ( Figure 10 Area 1010 in the image was exposed with a high dose of light, and the portion that needs to be retained ( Figure 10 Region 1020 in the image uses low-dose exposure. For example... Figure 10 As shown in section (b), during the development process, the photoresist in the high-dose region is dissolved by the developer, while the photoresist in the low-dose region remains, forming an arched structure. Then, an air-bridge bandage is fabricated to complete the connection between the underlying tantalum film and the Josephson junction.

[0172] Among them, the above Figures 7 to 10 The preparation process is described from the perspective of a single air bridge; in the above embodiments of this application, two air bridges can be prepared simultaneously; or, two air bridges can be prepared in different preparation processes.

[0173] Please refer to Figure 11 The diagram illustrates a fabrication process of a superconducting circuit according to an embodiment of this application.

[0174] like Figure 11 As shown, the two air bridges in this superconducting circuit are fabricated simultaneously, and the fabrication process can be as follows:

[0175] Step S1: Prepare peripheral circuit 1101 and junction circuit, the junction circuit including first lead 1102 and second lead 1103.

[0176] Step S2: By photolithography development and reflow processing, or by grayscale exposure, an arched photoresist structure 1104 between the peripheral circuit 1101 and the first lead 1102, and an arched photoresist structure 1105 between the peripheral circuit 1101 and the second lead 1103 are prepared.

[0177] Step S3: Prepare a metal film layer 1106 on the upper layer of the arched photoresist structure, for example, by vapor deposition.

[0178] Step S4: Remove the portion of the metal film layer 1106 other than the first air bridge 1107 and the second air bridge 1108 by etching, peeling and other methods.

[0179] Please refer to Figure 12 This illustrates a flowchart of the fabrication process of another superconducting circuit according to an embodiment of this application. Figure 12 As shown, the two air bridges in this superconducting circuit are fabricated separately, and the fabrication process can be as follows:

[0180] Step S1: Prepare peripheral circuit 1201 and junction circuit. The junction circuit includes first lead 1202 and second lead 1203.

[0181] Step S2: The arched photoresist structure 1204 between the peripheral circuit 1201 and the first lead 1202 is prepared by photolithography development and reflow processing, or by grayscale exposure.

[0182] Step S3: Prepare a metal film layer 1205 on the upper layer of the arched photoresist structure, for example, by vapor deposition.

[0183] Step S4: Remove the portion of the metal film layer 1205 except for the first air bridge 1206.

[0184] Step S5: The arched photoresist structure 1207 between the peripheral circuit 1201 and the second lead 1203 is prepared by photolithography development and reflow processing, or by grayscale exposure.

[0185] Step S6: Prepare a metal film layer 1208 on the upper layer of the arched photoresist structure, for example, by vapor deposition.

[0186] Step S7: Remove the portion of the metal film layer 1208 except for the second air bridge 1209.

[0187] By using the solution shown in the above embodiments of this application, the underlying large circuit structure and Josephson junction are connected by an air bridge bandage, which can avoid parasitic junctions and substrate damage, thereby improving the performance of the superconducting circuit.

[0188] This application also provides a chip, the chip comprising: a substrate, and a superconducting circuit located on the substrate; the superconducting circuit includes a peripheral circuit, a junction circuit, a first air bridge, and a second air bridge; the junction circuit includes a first lead and a second lead; the first lead and the second lead intersect each other, and the intersection of the first lead and the second lead forms a Josephson junction; the first lead is connected to the peripheral circuit through the first air bridge; the second lead is connected to the peripheral circuit through the second air bridge.

[0189] The structure of the superconducting circuit in this chip can be as follows: Figure 3 As shown.

[0190] Please refer to Figure 13 This illustration shows a schematic diagram of a product application scenario provided by one embodiment of this application. For example... Figure 13 As shown, the computing device products prepared according to the embodiments of this application can be applied to... Figure 13 The application scenario shown can be a superconducting computing platform, which includes: computing device 131, dilution refrigerator 132, control device 133 and computer 134.

[0191] The computing device 131 is a circuit operating on physical bits. The computing device 131 can be implemented as a superconducting chip, such as a superconducting chip located near absolute zero. The dilution refrigerator 132 is used to provide an absolute zero environment for the superconducting chip. The aforementioned physical bits can be Josephson junctions prepared by the method shown in the above embodiments of this application.

[0192] Control device 133 controls computing device 131, and computer 134 controls control device 133. For example, a written program is compiled into instructions by software in computer 134 and sent to control device 133 (such as an electronic / microwave control system). Control device 133 converts these instructions into electronic / microwave control signals and inputs them to dilution refrigerator 132 to control the superconducting bit at a temperature less than 10 mK. The reading process is the reverse; the read waveform is sent to computing device 131.

[0193] Figure 14 A schematic diagram of a superconducting circuit fabrication system illustrated in an exemplary embodiment of this application is shown. This superconducting circuit fabrication system can be implemented as production line equipment; as shown Figure 14 As shown, the superconducting circuit fabrication system may include: a coating subsystem 1401, a photolithography subsystem 1402, a vapor deposition subsystem 1403, an etching subsystem 1404, and a cleaning subsystem 1405.

[0194] The coating subsystem 1401, photolithography subsystem 1402, vapor deposition subsystem 1403, etching subsystem 1404, and cleaning subsystem 1405 are used to fabricate the peripheral circuits of a superconducting circuit on a substrate.

[0195] The coating subsystem 1401, photolithography subsystem 1402, vapor deposition subsystem 1403, etching subsystem 1404, and cleaning subsystem 1405 are used to fabricate a junction circuit on a substrate; the junction circuit includes a first lead and a second lead; the first lead and the second lead intersect each other, and the intersection of the first lead and the second lead constitutes a Josephson junction;

[0196] The coating subsystem 1401, photolithography subsystem 1402, vapor deposition subsystem 1403, etching subsystem 1404, and cleaning subsystem 1405 are used to prepare a first air bridge between the first lead and the peripheral circuit, and a second air bridge between the second lead and the peripheral circuit.

[0197] In one possible implementation, the photoresist coating subsystem 1401 is used to coat a substrate containing peripheral circuits and junction circuits with photoresist.

[0198] The photolithography subsystem 1402 and the cleaning subsystem 1405 are used to prepare an arched photoresist structure, which is located between a first region on the peripheral circuit and a second region on the first lead, and between a third region on the peripheral circuit and a fourth region on the second lead. The photoresist corresponding to the first and second regions and the photoresist corresponding to the third and fourth regions are removed.

[0199] Evaporation subsystem 1403 is used to prepare metal films on photoresist;

[0200] The coating subsystem 1401, photolithography subsystem 1402, etching subsystem 1404, and cleaning subsystem 1405 are used to remove the metal film layer from the metal film layer except between the first region and the second region, and between the third region and the fourth region, to obtain the first air bridge and the second air bridge.

[0201] The cleaning subsystem 1405 is used to remove residual photoresist from the substrate.

[0202] In one possible implementation, the photolithography subsystem 1402 and the cleaning subsystem 1405 are used to perform exposure and development processes on the photoresist in the first region and the second region, as well as the photoresist in the third region and the fourth region, to remove the photoresist in the first region and the second region and the photoresist corresponding to the third region and the fourth region.

[0203] The superconducting circuit fabrication system also includes:

[0204] The reflow subsystem is used to perform reflow processing on the remaining photoresist on the substrate.

[0205] In one possible implementation, the reflow processing time is 2 to 4 minutes.

[0206] In one possible implementation, the reflux temperature is between 130 and 150 degrees Celsius.

[0207] In one possible implementation, the photolithography subsystem 1402 is used to perform exposure on the region of the photoresist on the substrate corresponding to the arched photoresist structure using a first exposure dose; and to perform exposure on the other regions of the photoresist on the substrate other than the arched photoresist structure using a second exposure dose; the second exposure dose is higher than the first exposure dose.

[0208] The cleaning subsystem 1405 is used to perform a development process on the exposed photoresist to remove photoresist from areas other than the arched photoresist structure.

[0209] In one possible implementation, the etching subsystem 1404 is also used to perform etching on the first region, the second region, the third region, and the fourth region before the evaporation subsystem 1403 prepares the metal film layer on the photoresist, so as to remove the oxide layer on the peripheral circuit corresponding to the first region and the third region, the oxide layer on the first lead corresponding to the second region, and the oxide layer on the second lead corresponding to the fourth region.

[0210] In one possible implementation, the etching subsystem 1404 is used to perform etching on areas of the metal film other than the areas corresponding to the first air bridge and the second air bridge.

[0211] In one possible implementation, the etching subsystem 1404 is used to perform etching on the metal film at the edge locations of the first air bridge and the second air bridge.

[0212] The cleaning subsystem 1405 is used to perform cleaning of the photoresist on the substrate.

[0213] In one possible implementation, the metal film layer is made of the same material as the surrounding circuitry, or;

[0214] The material of the metal film layer is the same as the material of the junction circuit, or;

[0215] The material of the metal film layer is the same as that of the peripheral circuit and the junction circuit.

[0216] In one exemplary embodiment, a computer-readable storage medium is also provided, which stores at least one computer instruction that is executed by a processor in a superconducting circuit fabrication system to cause the superconducting circuit fabrication system to perform the superconducting circuit fabrication method described above.

[0217] In an exemplary embodiment, a computer program product or computer program is also provided, which includes computer instructions stored in a computer-readable storage medium. A processor of the production line equipment reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the superconducting circuit fabrication system to perform the described superconducting circuit fabrication method.

[0218] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the claims.

[0219] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A superconducting circuit, characterized in that, The superconducting circuit includes a peripheral circuit, a junction circuit, a first air bridge, and a second air bridge. The junction circuit includes a first lead and a second lead; the first lead and the second lead intersect each other, and the intersection of the first lead and the second lead forms a Josephson junction; The first lead is connected to the peripheral circuit via the first air bridge; The second lead is connected to the peripheral circuit via the second air bridge.

2. The superconducting circuit according to claim 1, characterized in that, The material of the first air bridge and the material of the second air bridge are the same as the material of the peripheral circuit, or; The material of the first air bridge and the material of the second air bridge are the same as the material of the junction circuit, or; The materials of the first air bridge and the second air bridge are the same as the materials of the peripheral circuit and the junction circuit.

3. A method for fabricating a superconducting circuit, characterized in that, The method includes: Fabricating the peripheral circuitry of a superconducting circuit on a substrate; A junction circuit is fabricated on the substrate; the junction circuit includes a first lead and a second lead; the first lead and the second lead intersect each other, and the intersection of the first lead and the second lead forms a Josephson junction; A first air bridge is prepared between the first lead and the peripheral circuit, and a second air bridge is prepared between the second lead and the peripheral circuit.

4. The method according to claim 3, characterized in that, The process of creating a first air bridge between the first lead and the peripheral circuit, and a second air bridge between the second lead and the peripheral circuit, includes: Photoresist is coated on a substrate containing the peripheral circuit and the junction circuit; An arched photoresist structure is fabricated, the arched photoresist structure being located between a first region on the peripheral circuit and a second region on the first lead, and between a third region on the peripheral circuit and a fourth region on the second lead, wherein the photoresist corresponding to the first region and the second region, as well as the photoresist corresponding to the third region and the fourth region, is removed; A metal film layer is prepared on the photoresist; Remove the metal film layer except between the first region and the second region, and between the third region and the fourth region, to obtain the first air bridge and the second air bridge; Remove residual photoresist from the substrate.

5. The method according to claim 4, characterized in that, The preparation of the arched photoresist structure includes: Exposure and development processes are performed on the photoresist in the first region and the second region, as well as the photoresist in the third region and the fourth region, to remove the photoresist in the first region and the second region, as well as the photoresist in the third region and the fourth region. The remaining photoresist on the substrate is subjected to a reflow process.

6. The method according to claim 5, characterized in that, The reflux process takes 2 to 4 minutes.

7. The method according to claim 5 or 6, characterized in that, The reflux treatment temperature is between 130 and 150 degrees Celsius.

8. The method according to claim 4, characterized in that, The preparation of the arched photoresist structure includes: Exposure is performed on the region of the photoresist on the substrate corresponding to the arched photoresist structure using a first exposure dose; Exposure is performed on the photoresist on the substrate using a second exposure dose, except for the arched photoresist structure; the second exposure dose is higher than the first exposure dose. The exposed photoresist is subjected to a development process to remove photoresist from areas other than the arched photoresist structure.

9. The method according to any one of claims 4 to 8, characterized in that, Before fabricating the metal film layer on the photoresist, the method further includes: Etching is performed on the first region, the second region, the third region, and the fourth region to remove the oxide layers on the peripheral circuit corresponding to the first region and the third region, the oxide layer on the first lead corresponding to the second region, and the oxide layer on the second lead corresponding to the fourth region.

10. The method according to any one of claims 4 to 9, characterized in that, The removal of the metal film layer, excluding the metal film layer between the first region and the second region, and between the third region and the fourth region, to obtain the first air bridge and the second air bridge, includes: Etching is performed on the regions of the metal film layer other than those corresponding to the first air bridge and the second air bridge.

11. The method according to any one of claims 4 to 9, characterized in that, The removal of the metal film layer, excluding the metal film layer between the first region and the second region, and between the third region and the fourth region, to obtain the first air bridge and the second air bridge, includes: Etching is performed on the metal film layers at the edge positions of the first air bridge and the second air bridge; The photoresist on the substrate is cleaned.

12. The method according to any one of claims 4 to 11, characterized in that, The material of the metal film layer is the same as the material of the peripheral circuit, or; The material of the metal film layer is the same as the material of the junction circuit, or; The material of the metal film layer is the same as the material of the peripheral circuit and the junction circuit.

13. A superconducting circuit fabrication system, characterized in that, The system includes: a coating subsystem, a photolithography subsystem, a vapor deposition subsystem, an etching subsystem, and a cleaning subsystem; The coating subsystem, the photolithography subsystem, the evaporation subsystem, the etching subsystem, and the cleaning subsystem are used to fabricate the peripheral circuitry of a superconducting circuit on a substrate. The coating subsystem, the photolithography subsystem, the evaporation subsystem, the etching subsystem, and the cleaning subsystem are used to fabricate a junction circuit on the substrate; the junction circuit includes a first lead and a second lead; the first lead and the second lead intersect each other, and the intersection of the first lead and the second lead constitutes a Josephson junction; The coating subsystem, the photolithography subsystem, the vapor deposition subsystem, the etching subsystem, and the cleaning subsystem are used to prepare a first air bridge between the first lead and the peripheral circuit, and a second air bridge between the second lead and the peripheral circuit.

14. A chip, characterized in that, The chip includes: a substrate and a superconducting circuit located on the substrate; The superconducting circuit includes a peripheral circuit, a junction circuit, a first air bridge, and a second air bridge. The junction circuit includes a first lead and a second lead; the first lead and the second lead intersect each other, and the intersection of the first lead and the second lead forms a Josephson junction; The first lead is connected to the peripheral circuit via the first air bridge; The second lead is connected to the peripheral circuit via the second air bridge.

Images