Preparation method and structure of series superconducting quantum interference device array based on superconducting bridge junction

Abstract

The present application provides a method and structure for preparing a series superconducting quantum interference device array based on a superconducting bridge junction. The series superconducting quantum interference device array structure based on a superconducting bridge junction has a nanobridge structure, forming a plurality of series-connected SQUID arrays. Thus, it has the characteristics of high junction current density and small parasitic capacitance. The series superconducting quantum interference device array structure with a nanojunction can be reduced to the nanoscale, and has a higher ability to resist interference from external magnetic fields. Through the series-connected SQUID array, the entire system of the series superconducting quantum interference device array structure based on a superconducting bridge junction has a larger bandwidth, avoids impedance matching problems, and greatly increases the operating frequency range. Thus, the series superconducting quantum interference device array structure based on a superconducting bridge junction prepared has a stronger anti-interference ability, a higher bandwidth, and a better output signal-to-noise ratio.

Description

Technical Field

[0001] The present application relates to the technical field of electronic devices, and in particular to a method and structure for preparing a series superconducting quantum interference device array based on superconducting bridge junctions. Background Art

[0002] Superconducting Quantum Interference Device (SQUID) is currently the most sensitive flux-voltage sensor. It can accurately measure physical quantities such as magnetic field (gradient), current, voltage, displacement, etc. that can be converted into magnetic flux through self-inductance and mutual inductance. It has a wide range of applications in precision measurement, aerospace, geophysics, ocean exploration, biology and medicine.

[0003] The traditional preparation method of superconducting quantum interference device and superconducting quantum interference device adopt parallel Josephson junction, and the Josephson junction adopts the three-layer structure of superconductor-ultra-thin insulator superconductor-superconductor. At this time, the traditional preparation method of superconducting quantum interference device and superconducting quantum interference device, the Josephson junction has low current density, large parasitic capacitance, and complex process preparation flow. Summary of the invention

[0004] Based on this, it is necessary to provide a method and structure for preparing a series superconducting quantum interference device array based on superconducting bridge junctions to address the above problems.

[0005] The present application provides a method for preparing a series superconducting quantum interference device array based on a superconducting bridge junction, comprising:

[0006] S10, providing a substrate, and preparing a superconducting thin film on the surface of the substrate;

[0007] S20, preparing a first mask layer on a surface of the superconducting thin film away from the substrate, etching the superconducting thin film according to the first mask layer to form a superconducting thin film structure, and removing the first mask layer;

[0008] S30, preparing an insulating layer on the surface of the superconducting thin film structure away from the substrate;

[0009] S40, preparing a second mask layer on a surface of the insulating layer away from the superconducting thin film structure, etching the insulating layer according to the second mask layer to form an insulating structure, and removing the second mask layer;

[0010] S50, preparing a superconducting thin film lead layer on the surface of the insulating structure away from the substrate and the surface of the superconducting thin film structure away from the substrate;

[0011] S60, preparing a third mask layer on a surface of the superconducting thin film lead layer away from the substrate, etching the superconducting thin film lead layer according to the third mask layer to form a first superconducting thin film lead structure and a second superconducting thin film lead structure, and removing the third mask layer;

[0012] S70, preparing a terminal resistor near the insulating structure and the first superconducting film lead structure;

[0013] S80, etching the second superconducting film lead structure to the insulating structure, preparing nano-ring holes and nano-bridges, and obtaining a series superconducting quantum interference device array structure based on superconducting bridge junctions.

[0014] In one embodiment, in S80, the nano-ring hole and the nano-bridge are prepared by using a focused ion beam etching method.

[0015] In one embodiment, in S80, the nano-ring hole and the nano-bridge are prepared by electron beam lithography combined with dry etching.

[0016] In one embodiment, when the focused ion beam etching method is used, the voltage is set to 28 keV to 31 keV, and the beam current is set to 4.7 nm to 5 nm.

[0017] In one embodiment, in S20, the superconducting thin film is etched by using a reactive ion etching method combined with an endpoint detection method to form the superconducting thin film structure.

[0018] In one embodiment, in S10, a magnetron sputtering method is used to control the argon sputtering pressure and / or regulate the superconducting material sputtering power to prepare the superconducting film on the substrate surface.

[0019] In one embodiment, in S30, at a temperature below 100 degrees, a low-temperature plasma-assisted chemical vapor deposition method is used to adjust silane within a range of 30 sccm to 70 sccm and oxygen within a range of 40 sccm to 60 sccm to prepare the insulating layer on the surface of the superconducting thin film structure away from the substrate.

[0020] In one embodiment, in the step S40, the etching gas CHF is adjusted according to the second mask layer. 3 The range is 70sccm~100sccm, O 2 The insulating layer is etched within a range of 100 sccm to 150 sccm to form the insulating structure.

[0021] In one embodiment, in S60, the etching gas SF is adjusted according to the third mask layer. 6The range is 7sccm~30sccm, C 4 F 8 The range is 15 sccm to 45 sccm, and the superconducting thin film lead layer is etched to form the first superconducting thin film lead structure and the second superconducting thin film lead structure.

[0022] In one embodiment, the present application provides a series superconducting quantum interference device array structure based on superconducting bridge junctions, which is prepared using the series superconducting quantum interference device array preparation method based on superconducting bridge junctions as described in any of the above embodiments.

[0023] In one embodiment, the series superconducting quantum interference device array structure based on superconducting bridge junctions includes a substrate, a plurality of superconducting thin film structures, a plurality of insulating structures, a plurality of second superconducting thin film lead substructures, and a plurality of nanobridges. The plurality of second superconducting thin film lead substructures are located on the surface of the insulating structure between two adjacent superconducting thin film structures. The plurality of nanobridges are located on the surface of the insulating structure between two adjacent superconducting thin film structures, and connect the plurality of second superconducting thin film lead substructures in sequence;

[0024] The plurality of second superconducting thin film lead substructures surround and form at least one nano-ring hole.

[0025] The present application provides the above-mentioned preparation method and structure of the series superconducting quantum interference device array based on superconducting bridge junction. The superconducting quantum interference device prepared by the preparation method of the series superconducting quantum interference device array based on superconducting bridge junction has a nanobridge structure, forming a plurality of series SQUID arrays. Thus, compared with the traditional superconducting quantum interference device, the superconducting quantum interference device with nanobridge structure has the characteristics of high junction current density and small parasitic capacitance. Moreover, the series superconducting quantum interference device array structure based on superconducting bridge junction can be reduced to nanometer level, and has a higher ability to resist interference from external magnetic fields.

[0026] At the same time, through the series SQUID array, the entire system of the series superconducting quantum interference device array structure based on superconducting bridge junctions has a larger bandwidth, including impedance matching and flux locking loops. In order to achieve the best sensitivity, the series superconducting quantum interference device array structure based on superconducting bridge junctions solves the problem that a single SQUID can only reach the room temperature electronic circuit through AC modulation and transformers. At this time, through the series superconducting quantum interference device array structure based on superconducting bridge junctions, the peak-to-peak amplitude can be made to be 10mV, and the output can be directly fed to a low-noise room temperature preamplifier without losing sensitivity. The series superconducting quantum interference device array structure based on superconducting bridge junctions greatly increases the operating frequency range by avoiding impedance matching problems.

[0027] Therefore, through the method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions, the process preparation process is simple, so that the prepared series superconducting quantum interference device array structure based on superconducting bridge junctions has stronger anti-interference ability, higher bandwidth and better output signal-to-noise ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A schematic diagram of the process flow of a method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions provided in this application.

[0030] Figure 2 This is a schematic diagram of the structure of the substrate and superconducting film provided in this application.

[0031] Figure 3 This is a schematic structural diagram of the first mask layer provided in this application.

[0032] Figure 4 This is a schematic diagram of the structure of the superconducting thin film provided in this application.

[0033] Figure 5 This is a schematic diagram of the structure of the insulating layer and superconducting film provided in this application.

[0034] Figure 6 This is a schematic diagram of the structure of the second mask layer and the insulating layer provided in this application.

[0035] Figure 7 This is a schematic diagram of the structure of the insulation structure and the superconducting film structure provided in this application.

[0036] Figure 8 This is a schematic structural diagram of the superconducting film lead layer and insulation structure, and the superconducting film structure provided in this application.

[0037] Fig. 9 This is a schematic structural diagram of the third mask layer and the superconducting thin film lead layer provided in this application.

[0038] Fig.10 This is a schematic structural diagram of the first superconducting thin film lead structure and the second superconducting thin film lead structure provided in the present application.

[0039] Fig.11This is a schematic structural diagram of the first superconducting film lead structure, the second superconducting film lead structure, the terminal resistor, and the insulation structure provided in the present application.

[0040] Fig.12 A schematic diagram of the etched area pattern provided for this application.

[0041] Fig.13 A schematic diagram of etching according to the etching area pattern provided in this application.

[0042] Fig.14 A schematic top view of a series superconducting quantum interference device array structure based on superconducting bridge junctions provided in this application.

[0043] Fig.15 Provided for this application Fig.14 A partial top view is shown.

[0044] Description of Reference Numerals

[0045] Substrate 10, superconducting film 20, first mask layer 30, superconducting film structure 210, insulating layer 40, second mask layer 50, insulating structure 410, through-hole structure 411, superconducting film lead layer 60, third mask layer 70, first superconducting film lead structure 610, second superconducting film lead structure 620, second superconducting film lead substructure 621, terminal resistor 80, nano-ring hole 910, nano-bridge 920, etching area pattern 930, isolation groove 940. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0047] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings). In the description of this application, it should be understood that the orientation or position relationship indicated by the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. are based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application.

[0048] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being “above”, “above”, and “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below”, and “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0049] See also Figure 1 The present application provides a method for preparing a series superconducting quantum interference device array based on a superconducting bridge junction, comprising:

[0050] S10, providing a substrate 10, and preparing a superconducting thin film 20 on the surface of the substrate 10;

[0051] S20, preparing a first mask layer 30 on a surface of the superconducting film 20 away from the substrate 10, etching the superconducting film 20 according to the first mask layer 30 to form a superconducting film structure 210, and removing the first mask layer 30;

[0052] S30, preparing an insulating layer 40 on the surface of the superconducting thin film structure 210 away from the substrate 10;

[0053] S40, preparing a second mask layer 50 on a surface of the insulating layer 40 away from the superconducting thin film structure 210, etching the insulating layer 40 according to the second mask layer 50 to form an insulating structure 410, and removing the second mask layer 50;

[0054] S50, preparing a superconducting thin film lead layer 60 on the surface of the insulating structure 410 away from the substrate 10 and the surface of the superconducting thin film structure 210 away from the substrate 10;

[0055] S60, preparing a third mask layer 70 on the surface of the superconducting thin film lead layer 60 away from the substrate 10, etching the superconducting thin film lead layer 60 according to the third mask layer 70 to form a first superconducting thin film lead structure 610 and a second superconducting thin film lead structure 620, and removing the third mask layer 70;

[0056] S70, preparing a terminal resistor 80 near the insulating structure 410 and the first superconducting film lead structure 610;

[0057] S80, etching the second superconducting thin film lead structure 620 to the insulating structure 410, preparing nano-ring holes 910 and nano-bridges 920, and obtaining a series superconducting quantum interference device array structure based on superconducting bridge junctions.

[0058] See also Figure 2 In the S10, the substrate 10 is a silicon substrate with high resistivity, small roughness, flatness and an oxide layer. The superconducting film 20 is a Nb film.

[0059] See also Figure 3-4 In the S20, the first mask layer 30 is a photoresist layer. The first mask layer 30 is a patterned structure. The superconducting film 20 is etched according to the first mask layer 30 to form the superconducting film structure 210. The superconducting film structure 210 includes a bottom layer of an inductor and a capacitor structure.

[0060] See also Figure 5 In the S30, the insulating layer 40 is SiO 2 or / and SiN x .

[0061] See also Figure 6-7 In the S40, the second mask layer 50 is a photoresist layer. The second mask layer 50 is a patterned structure. The insulating layer 40 is etched according to the second mask layer 50 to form the insulating structure 410. Adjacent insulating structures 410 form a plurality of through-hole structures 411 for exposing a portion of the superconducting thin film structure 210.

[0062] See also Figure 8 In the step S50, the superconducting thin film lead layer 60 completely covers the insulating structure 410 and the superconducting thin film structure 210. At this time, the superconducting thin film lead layer 60 is deposited in the plurality of through-hole structures 411, so that the superconducting thin film lead layer 60 is connected to the superconducting thin film structure 210.

[0063] See also Figure 9-10 In the S60, the third mask layer 70 is a photoresist layer. The third mask layer 70 is a patterned structure. The superconducting thin film lead layer 60 is an upper Nb structure of the inductor and capacitor structure. The material of the superconducting thin film lead layer 60 is Nb material. The superconducting thin film lead layer 60 is etched according to the third mask layer 70 to form the first superconducting thin film lead structure 610 and the second superconducting thin film lead structure 620. A portion of the insulating structure 410 is exposed near one side of the first superconducting thin film lead structure 610 to prepare the terminal resistor 80.

[0064] See also Fig.11 In the S70 , the terminal resistor 80 is prepared near the insulating structure 410 and the first superconducting film lead structure 610 , covering the edge of the insulating structure 410 and the edge of the first superconducting film lead structure 610 .

[0065] See also Figure 12-13 In the S80, according to the etching area pattern 930, the surface of the second superconducting film lead structure 620 away from the insulating structure 410 is subjected to nano-micromachining treatment, and the second superconducting film lead structure 620 corresponding to the etching area of ​​the etching area pattern 930 is etched to the insulating structure 410 to form the nano-ring hole 910 and the nano-bridge 920. At this time, the remaining structure after etching the second superconducting film lead structure 620 is the second superconducting film lead substructure 621. Through the multiple nanobridges 920, the multiple second superconducting film lead substructures 621 can be weakly connected, and there is a Josephson effect to form a superconducting bridge junction array. In addition, the nano-ring hole 910 is surrounded by the multiple second superconducting film lead substructures 621. At this time, the superconducting quantum interference device prepared by the method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions has a nanobridge structure, and multiple series SQUID arrays are formed. At the same time, by providing at least one of the nano-ring holes 910 between the superconducting bridge junction arrays, the non-hysteresis temperature, critical current, transmission coefficient and bias current of the series superconducting quantum interference device array structure based on the superconducting bridge junction can be adjusted. Thus, compared with the traditional superconducting quantum interference device, the superconducting quantum interference device of the nanobridge structure has the characteristics of high junction current density and small parasitic capacitance. Moreover, the series superconducting quantum interference device array structure based on the superconducting bridge junction can be reduced to the nanometer level, and has a higher ability to resist external magnetic field interference.

[0066] At the same time, through the series SQUID array, the entire system of the series superconducting quantum interference device array structure based on superconducting bridge junctions has a larger bandwidth, including impedance matching and flux locking loops. In order to achieve the best sensitivity, the series superconducting quantum interference device array structure based on superconducting bridge junctions solves the problem that a single SQUID can only reach the room temperature electronic circuit through AC modulation and transformers. At this time, through the series superconducting quantum interference device array structure based on superconducting bridge junctions, the peak-to-peak amplitude can be made to be 10mV, and the output can be directly fed to a low-noise room temperature preamplifier without losing sensitivity. The series superconducting quantum interference device array structure based on superconducting bridge junctions greatly increases the operating frequency range by avoiding impedance matching problems.

[0067] Therefore, through the method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions, the process preparation process is simple, so that the prepared series superconducting quantum interference device array structure based on superconducting bridge junctions has stronger anti-interference ability, higher bandwidth and better output signal-to-noise ratio.

[0068] In one embodiment, in S80, the nano-ring hole 910 and the nano-bridge 920 are prepared by using a focused ion beam etching method.

[0069] In this embodiment, the second superconducting film lead structure 620 is micro-processed by a focused ion beam etching method, thereby achieving fine trimming of the bridge junction to form a nano-scale nanobridge structure. The focused ion beam etching method makes the prepared nanobridge structure more precise, thereby improving the performance of the series superconducting quantum interference device array structure based on the superconducting bridge junction.

[0070] In one embodiment, according to the etching area pattern 930 (see Fig.12 ), by setting the voltage range in the focused ion beam etching method to 20KV to 40kV to accelerate gallium ions, the second superconducting thin film lead structure 620 can be etched in a low dimension and small size to form the nano-ring hole 910 and the nano-bridge 920. At this time, according to the etching area pattern 930, by accelerating the gallium ions to collide Fig.13 The etching area shown in the etching area pattern 930 (black area) is etched to the substrate 10 to form the nano-ring hole 910 and the nano-bridge 920 (see Fig.14 and Fig.15 ).

[0071] By setting the voltage and beam parameters in the focused ion beam etching method, the process is controllable and stable, so that the performance of the prepared series superconducting quantum interference device array structure based on superconducting bridge junctions is better and it is easier to control during the preparation process.

[0072] A voltage of 30 kV is used to accelerate Ga ions and bombard the area to be removed to leave a nanoscale structure, thereby preparing the nano-ring hole 910 and the nano-bridge 920. The nano-bridge 920 can realize a weak connection between the plurality of second superconducting film lead substructures 621, and a Josephson effect exists.

[0073] In one embodiment, in S80, the nano-ring hole 910 and the nano-bridge 920 are prepared by electron beam lithography combined with dry etching.

[0074] In this embodiment, according to the etching area pattern 930 (see Fig.12), using an electron beam lithography method, a photoresist structure is prepared on the surface of the second superconducting thin film lead structure 620 away from the insulating structure 410. According to the photoresist structure, a reactive ion etching method is used, and the etching pressure range is set to 10mTorr to 20mTorr, the power range is set to 40W to 100W, and the etching gas SF 6 The etching is performed in the range of 20 sccm to 40 sccm, through the second superconducting film lead structure 620, to the insulating structure 410, to form the nano-ring hole 910 and the nano-bridge 920, and further to form the series superconducting quantum interference device array structure based on the superconducting bridge junction.

[0075] By combining electron beam lithography and reactive ion etching, the etching pressure range, power range, and etching gas SF 6 Etching within a certain range can avoid the occurrence of etching errors, and can ensure that the insulating structure 410 will not be etched away when the unnecessary parts are etched cleanly. Therefore, the etching process can be accurately and stably controlled, the accuracy of the lines can be improved, and the performance of the prepared device can be improved.

[0076] Specifically, ZEP520 glue was used, and after being coated, baked and exposed, a dry etcher was used for etching. The etching pressure was set to 15mT, the power of reactive ion etching was set to 50W, and the SF 6 The etching is performed with a gas flow rate of 30 sccm until the insulating structure 410 is etched, a portion of the insulating structure 410 is exposed, and the nano-ring hole 910 and the nano-bridge 920 are formed.

[0077] In one embodiment, in S20 , the superconducting film 20 is etched by using a reactive ion etching method combined with an endpoint detection method to form the superconducting film structure 210 .

[0078] In this embodiment, the optical endpoint detection method determines the etching position based on the optical path difference between visible light and reflected light. In addition, due to the different optical reflection intensities at the interfaces of different films, the dynamics of the etching position can be monitored. In the process of etching the superconducting film 20 by reactive ion etching, by combining the optical endpoint detection method, the etching process of the superconducting film 20 can be accurately and stably controlled, etching errors can be avoided, and excess superconducting materials can be removed.

[0079] In one embodiment, in S10 , a magnetron sputtering method is used to control the argon sputtering pressure and / or regulate the superconducting material sputtering power to prepare the superconducting film 20 on the surface of the substrate 10 .

[0080] In this embodiment, during the preparation process using the magnetron sputtering method, the stress of the superconducting film 20 can be changed by adjusting the argon sputtering pressure, or adjusting the superconducting material sputtering power, or adjusting the argon sputtering pressure and the superconducting material sputtering power at the same time. At this time, the stress of the superconducting film 20 can be adjusted according to the argon sputtering pressure and / or the superconducting material sputtering power, so that the overall stress of the superconducting film 20 is reduced, which is conducive to improving the film performance. Thus, the superconducting film is formed, which can effectively improve the performance and stability of the superconducting circuit device.

[0081] In one embodiment, in S60, a magnetron sputtering method is used to control the argon sputtering pressure and / or regulate the superconducting material sputtering power to prepare the superconducting thin film lead layer 60. The stress of the superconducting thin film lead layer 60 can be adjusted by the argon sputtering pressure and / or the superconducting material sputtering power, so that the overall stress of the superconducting thin film lead layer 60 is reduced, which is beneficial to improving the performance of the film. Therefore, the performance and stability of the superconducting circuit device can be effectively improved.

[0082] In one embodiment, in S30, at a temperature below 100 degrees, a low-temperature plasma-assisted chemical vapor deposition method is used to adjust silane within a range of 30 sccm to 70 sccm and oxygen within a range of 40 sccm to 60 sccm, and the insulating layer 40 is prepared on the surface of the superconducting thin film structure 210 away from the substrate 10.

[0083] The insulating layer 40 may be SiO 2 or SiN x Or SiO 2 and SiN x Double-layer structure, etc. Below 100 degrees, during the growth of the insulating layer 40, the superconducting film structure 210 will not be oxidized, thereby ensuring the performance of the superconducting film structure 210. At the same time, by adopting a low-temperature plasma-assisted chemical vapor deposition method, regulating silane in the range of 30sccm to 70sccm and oxygen in the range of 40sccm to 60sccm, the stress of the insulating layer 40 can be adjusted, so that the overall stress of the insulating layer 40 is reduced, and the superconducting characteristics of the superconducting film structure 210 will not be affected, which can effectively improve the performance and stability of superconducting circuit devices.

[0084] In one embodiment, in the S40, the etching gas CHF is adjusted according to the second mask layer 50. 3 The range is 70sccm~100sccm, O 2 The insulating layer 40 is etched within a range of 100 sccm to 150 sccm to form the insulating structure 410 .

[0085] In this embodiment, by adjusting the etching gas CHF 3 The range is 70sccm~100sccm, O 2 The range is 100sccm to 150sccm to achieve proportional adjustment. Reactive ion etching or inductively coupled plasma etching is used, and the gas pressure range is set to 10mTorr to 17mTorr, CHF 3 The range is 70sccm~100sccm, O 2 The range is 100sccm to 150sccm, and the power is set to 100W to 400W. By adjusting the etching gas CHF 3 and O 2 , the occurrence of etching errors can be avoided, and the superconducting thin film structure 210 can be ensured not to be etched away when the unnecessary parts of the insulating layer 40 are etched cleanly. Thus, the etching process of the insulating layer 40 can be accurately and stably controlled.

[0086] In one embodiment, in S60, the etching gas SF is adjusted according to the third mask layer 70. 6 The range is 7sccm~30sccm, C 4 F 8 The superconducting thin film lead layer 60 is etched at a temperature in a range of 15 sccm to 45 sccm to form the first superconducting thin film lead structure 610 and the second superconducting thin film lead structure 620 .

[0087] In this embodiment, reactive ion etching or inductively coupled plasma etching is used, the gas pressure range is set to 10mTorr to 18mTorr, the power is set to 100W to 300W, and the etching gas SF is adjusted. 6 The range is 7sccm~30sccm, C 4 F 8 The range is 15sccm~45sccm, which can realize the etching gas SF 6 and C 4 F 8 Thus, it can be ensured that the insulating structure 410 will not be etched away when the unnecessary parts of the superconducting thin film lead layer 60 are etched cleanly. Thus, the etching process of the insulating structure 410 can be accurately and stably controlled.

[0088] In one embodiment, in S70 , the terminal resistor 80 is prepared near the insulating structure 410 and the first superconducting thin film lead structure 610 .

[0089] In this embodiment, when preparing the terminal resistor 80, magnetron sputtering or electron beam evaporation method can be used to perform photolithography and stripping.

[0090] In one embodiment, the photolithography in the above embodiment adopts ultraviolet contact exposure technology combined with dry etching technology to prepare a structure with a minimum size of more than 2 μm.

[0091] In one embodiment, the present application provides a series superconducting quantum interference device array structure based on superconducting bridge junctions, which is prepared by the series superconducting quantum interference device array preparation method based on superconducting bridge junctions described in any one of the above embodiments. The series superconducting quantum interference device array structure based on superconducting bridge junctions includes a substrate 10, a plurality of superconducting film structures 210, a plurality of insulating structures 410, a plurality of second superconducting film lead substructures 621, and a plurality of nanobridges 920. The plurality of second superconducting film lead substructures 621 are located on the surface of the insulating structure 410 between two adjacent superconducting film structures 210. The plurality of nanobridges 920 are located on the surface of the insulating structure 410 between two adjacent superconducting film structures 210, and the plurality of second superconducting film lead substructures 621 are connected in sequence. The plurality of second superconducting film lead substructures 621 surround at least one nano-ring hole 910.

[0092] In this embodiment, the plurality of superconducting thin film structures 210 are disposed at intervals on the surface of the substrate 10. The plurality of insulating structures 410 are disposed on a portion of the surface of the substrate 10 to separate the plurality of superconducting thin film structures 210 and to insulate the plurality of superconducting thin film structures 210.

[0093] The plurality of second superconducting film lead substructures 621 are connected by the plurality of nanobridges 920, so that the plurality of second superconducting film lead substructures 621 are connected in series. At the same time, the plurality of second superconducting film lead substructures 621 surround and form at least one of the nanoring holes 910. Thus, a plurality of series-connected SQUID arrays are formed. Compared with the traditional superconducting quantum interference device, the superconducting quantum interference device of the nanobridge structure has the characteristics of high junction current density and small parasitic capacitance. Moreover, the series superconducting quantum interference device array structure based on the superconducting bridge junction can be reduced to the nanometer level, and has a higher ability to resist external magnetic field interference.

[0094] At the same time, through the series connection of SQUID arrays, the whole system based on the series connection of superconducting quantum interference device array structure of superconducting bridge junction has a larger bandwidth, including impedance matching and flux locking loop. In order to achieve the best sensitivity, the series connection of superconducting quantum interference device array structure based on superconducting bridge junction solves the problem that a single SQUID can only reach room temperature electronic circuit through AC modulation and transformer.

[0095] Moreover, through the series superconducting quantum interference device array structure based on superconducting bridge junctions, the peak-to-peak amplitude can be made to be 10mV, and the output can be directly fed to a low-noise room temperature preamplifier without losing sensitivity. The series superconducting quantum interference device array structure based on superconducting bridge junctions greatly increases the operating frequency range by avoiding impedance matching problems. Therefore, the series superconducting quantum interference device array structure based on superconducting bridge junctions has stronger anti-interference ability, higher bandwidth and better output signal-to-noise ratio.

[0096] The plurality of second superconducting film lead substructures 621 are connected to each other through the plurality of nanobridges 920, forming a superconducting bridge junction array of a single superconducting film, and obtaining a Josephson junction array structure. At this time, since the Josephson junction array structure is formed by a single superconducting film, the size of the single superconducting film can be controlled.

[0097] In one embodiment, the series superconducting quantum interference device array structure based on superconducting bridge junctions further includes an isolation slot 940, the size of which is nanometer-level. By providing the isolation slot 940, adjacent superconducting wires are not connected together, but are close to each other, so as to improve the electrical coupling between them.

[0098] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions, characterized in that: include: S10, providing a substrate (10), and preparing a superconducting thin film (20) on the surface of the substrate (10); S20, preparing a first mask layer (30) on a surface of the superconducting film (20) away from the substrate (10), etching the superconducting film (20) according to the first mask layer (30) to form a superconducting film structure (210), wherein the superconducting film structure (210) includes a bottom layer of an inductor and a capacitor structure, and removing the first mask layer (30); S30, preparing an insulating layer (40) on a surface of the superconducting thin film structure (210) away from the substrate (10); S40, preparing a second mask layer (50) on a surface of the insulating layer (40) away from the superconducting thin film structure (210), etching the insulating layer (40) according to the second mask layer (50) to form an insulating structure (410), forming a plurality of through-hole structures (411) adjacent to the insulating structures (410) to expose a portion of the superconducting thin film structure (210), and removing the second mask layer (50); S50, preparing a superconducting thin film lead layer (60) on a surface of the insulating structure (410) away from the substrate (10) and a surface of the superconducting thin film structure (210) away from the substrate (10), wherein the superconducting thin film lead layer (60) includes an upper layer of an inductor and capacitor structure; S60, preparing a third mask layer (70) on a surface of the superconducting thin film lead layer (60) away from the substrate (10), etching the superconducting thin film lead layer (60) according to the third mask layer (70) to form a first superconducting thin film lead structure (610) and a second superconducting thin film lead structure (620), exposing a portion of the insulating structure (410) near one side of the first superconducting thin film lead structure (610), and removing the third mask layer (70); S70, preparing a terminal resistor (80) at a position close to the insulating structure (410) and the first superconducting thin film lead structure (610); S80, etching the second superconducting thin film lead structure (620) until it reaches the insulating structure (410), preparing a nano-ring hole (910) and a nano-bridge (920); the remaining structure of the second superconducting thin film lead structure (620) after etching is formed into a second superconducting thin film lead substructure (621); a plurality of second superconducting thin film lead substructures (621) surround the nano-ring hole (910); a weak connection is achieved between the plurality of second superconducting thin film lead substructures (621) through the plurality of nano-bridges (920), forming a Josephson effect, and obtaining a series superconducting quantum interference device array structure based on a superconducting bridge junction.

2. The method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions according to claim 1, characterized in that: In the S80, the nano-ring hole (910) and the nano-bridge (920) are prepared by using a focused ion beam etching method.

3. The method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions according to claim 1, characterized in that: In the S80, the nano-ring hole (910) and the nano-bridge (920) are prepared by electron beam lithography combined with dry etching.

4. The method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions according to claim 1, characterized in that: In the S20, the superconducting thin film (20) is etched using a reactive ion etching combined with endpoint detection method to form the superconducting thin film structure (210).

5. The method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions according to claim 1, characterized in that: In the S10, a magnetron sputtering method is used to control the argon sputtering pressure and / or regulate the superconducting material sputtering power to prepare the superconducting film (20) on the surface of the substrate (10).

6. The method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions according to claim 1, characterized in that: In the S30, at a temperature below 100 degrees, a low-temperature plasma-assisted chemical vapor deposition method is used to adjust the silane in the range of 30 sccm to 70 sccm and the oxygen in the range of 40 sccm to 60 sccm, and the insulating layer (40) is prepared on the surface of the superconducting thin film structure (210) away from the substrate (10).

7. The method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions according to claim 1, characterized in that: In the S40, according to the second mask layer (50), the etching gas CHF3 is adjusted within the range of 70 sccm to 100 sccm, and the O2 is adjusted within the range of 100 sccm to 150 sccm, and the insulating layer (40) is etched to form the insulating structure (410).

8. The method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions according to claim 1, characterized in that: In the S60, according to the third mask layer (70), the etching gas SF6 is adjusted to a range of 7 sccm to 30 sccm, and the C4F8 is adjusted to a range of 15 sccm to 45 sccm, and the superconducting thin film lead layer (60) is etched to form the first superconducting thin film lead structure (610) and the second superconducting thin film lead structure (620).

9. A series superconducting quantum interference device array structure based on superconducting bridge junctions, characterized in that: The method for preparing a series superconducting quantum interference device array based on superconducting bridge junctions is used for preparation.

10. The series superconducting quantum interference device array structure based on superconducting bridge junction according to claim 9, characterized in that: include: A substrate (10); A plurality of superconducting thin film structures (210) are spaced apart and located on the surface of the substrate (10); A plurality of insulating structures (410) are spaced apart and located on the surface of the substrate (10), and the insulating structures (410) are arranged between two adjacent superconducting thin film structures (210); A plurality of second superconducting thin film lead substructures (621), located on the surface of the insulating structure (410) between two adjacent superconducting thin film structures (210); A plurality of nanobridges (920) are located on the surface of the insulating structure (410) between two adjacent superconducting thin film structures (210) and connect the plurality of second superconducting thin film lead substructures (621) in sequence; The plurality of second superconducting thin film lead substructures (621) surround and form at least one nano-ring hole (910).

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