CN112289920A - Superconducting magnetic flux excitation switch based on SQUID array and preparation method thereof - Google Patents

Superconducting magnetic flux excitation switch based on SQUID array and preparation method thereof Download PDF

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CN112289920A
CN112289920A CN202011181251.6A CN202011181251A CN112289920A CN 112289920 A CN112289920 A CN 112289920A CN 202011181251 A CN202011181251 A CN 202011181251A CN 112289920 A CN112289920 A CN 112289920A
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thin film
structures
loop
superconducting thin
superconducting
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王仕建
徐达
王雪深
李劲劲
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National Institute of Metrology
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National Institute of Metrology
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/30—Devices switchable between superconducting and normal states
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H01L27/02—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier
    • H01L27/0203—Particular design considerations for integrated circuits
    • H01L27/0207—Geometrical layout of the components, e.g. computer aided design; custom LSI, semi-custom LSI, standard cell technique
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/01—Manufacture or treatment
    • H10N60/0912—Manufacture or treatment of Josephson-effect devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/10—Junction-based devices
    • H10N60/12—Josephson-effect devices

Abstract

The application relates to a superconducting magnetic flux excitation switch based on a SQUID array and a preparation method thereof. The first superconducting thin film structure of each first josephson junction structure is disposed at a first end of the loop structure. The first superconducting thin film structure of each second Josephson junction structure is disposed at the second end of the loop structure. The loop structure is an open loop having a first end and a second end. And connecting the first superconducting thin film structure of the first Josephson junction structure with the first superconducting thin film structure of the second Josephson junction structure through a loop structure, so that a series inductance structure is formed in the SQUID loop. Therefore, when a magnetic flux is obtained, the SQUID loop changes to be integral multiple of the magnetic flux quantum phi 0, and the V-phi 0 curve (the period is phi 0) cannot be changed at all, so that the phase offset of the SQUID loop can be effectively avoided, and the problem of phase offset caused by a parallel inductance structure is solved.

Description

Superconducting magnetic flux excitation switch based on SQUID array and preparation method thereof
Technical Field
The application relates to the technical field of communication, in particular to a superconducting magnetic flux excitation switch based on a SQUID array and a preparation method thereof.
Background
Superconducting quantum interferometer (SQUID) current sensors have wide applications in the fields of photon metering, cosmic astronomy, high-energy physics, quantum information and the like. The sensitivity of the high-performance TES detector is high, but the noise level is low, the output signal is weak, and the signal reading needs to adopt a SQUID current sensor with high current sensitivity and noise level matching. The SQUID current sensor is required for signal readout of all different types of TES detectors of different wavebands. Furthermore, SQUID current sensors have become the only means of TES detector signal readout.
For the weak signal readout of the TES array, readout technologies such as time division multiplexing SQUID, code division multiplexing SQUID, frequency division multiplexing SQUID, microwave multiplexing SQUID and the like are generally adopted. While in time division multiplexed SQUID and code division multiplexed SQUID readout technologies it is often necessary to use superconducting magnetic flux to energize switches to gate the readout. However, the conventional superconducting flux excitation switch is prone to phase shift, and is not favorable for reading weak signals of the TES array.
Disclosure of Invention
In view of the above, it is necessary to provide a superconducting magnetic flux excitation switch based on SQUID array and a method for manufacturing the same.
The application provides a superconducting magnetic flux excitation switch based on a SQUID array. The superconducting magnetic flux excitation switch based on the SQUID array comprises a plurality of loop structures, a plurality of first Josephson junction structures, a plurality of second Josephson junction structures, a plurality of positive pole connecting structures and a plurality of negative pole connecting structures.
Each of the loop structures has a first end and a second end. The first superconducting thin film structure of each first Josephson junction structure is arranged at a first end of the loop structure. The first superconducting thin film structure of each second Josephson junction structure is arranged at the second end of the loop structure. Each of the positive connection structures is connected to a first end of the loop structure. Each negative electrode connecting structure is respectively connected with the second superconducting thin film structure of the first Josephson junction structure and the second superconducting thin film structure of the second Josephson junction structure. And the cathode connecting structure corresponding to one loop structure is connected with the anode connecting structure corresponding to the adjacent loop structure.
In one embodiment, the SQUID array based superconducting magnetic flux actuated switch further comprises a control line structure. The control line structure is arranged on the surfaces of the loop structures in an insulating mode and used for inputting magnetic flux.
In one embodiment, each of the loop structures includes a first structure and a second structure. One end of the first structure is connected with the first superconducting thin film structure of the first Josephson junction structure. The other end of the first structure is connected with one end of the second structure. The other end of the second structure is connected with the first superconducting thin film structure of the second Josephson junction structure.
In one embodiment, the control line structure is arranged on the surface of the second structure in an insulated mode.
In one embodiment, the other end of the first structure is connected to one end of the second structure by a port connection structure. And the port connection structure is disposed on the surface of the first structure and the surface of the second structure 220.
In one embodiment, the loop structures are symmetrically disposed about the port connection structure.
In one embodiment, the SQUID array based superconducting magnetic flux actuated switch further comprises a plurality of termination resistors. Each of the termination resistances is connected in parallel with the first and second josephson junction structures.
In one embodiment, the SQUID array based superconducting magnetic flux actuated switch further comprises a resistive connection structure. One end of the resistor connecting structure is connected with the second superconducting thin film structure of the second Josephson junction structure. The other end of the resistor connecting structure is connected with one end of the terminal resistor. And the other end of the terminal resistor is connected with the positive electrode connecting structure.
In one embodiment, the first josephson junction structure and the first josephson junction structureThe second Josephson junction structure is Nb/Al-AlOxa/Nb three-layer film structure.
In one embodiment, the present application provides a method of making a superconducting magnetic flux actuated switch based on a SQUID array, comprising:
providing a substrate, and preparing a silicon dioxide film on the surface of the substrate;
sequentially preparing a first superconducting thin film layer, a first insulating layer and a second superconducting thin film layer on the surface of the silicon dioxide thin film, which is far away from the substrate;
etching the second layer of superconducting thin film to the first insulating layer to form a plurality of second superconducting thin film structures;
etching the first insulating layer to the first superconducting thin film layer to form a plurality of first insulating structures, wherein the area of each first insulating structure is larger than that of each second superconducting thin film structure;
etching the first superconducting thin film layer to the silicon dioxide thin film to form a plurality of loop structures and a plurality of first superconducting thin film structures;
preparing a second insulating layer on the surfaces of the silicon dioxide thin films, the surfaces of the loop structures, the surfaces of the first insulating structures and the surfaces of the second superconducting thin film structures;
etching the second insulating layer until the first superconducting thin film structures and the second superconducting thin film structures are etched respectively to form a plurality of connecting through holes and a plurality of second insulating structures;
preparing a plurality of terminal resistors on the surfaces of the second insulating structures among the connecting through holes;
depositing lead superconducting thin film layers on the surfaces of the connecting through holes and the second insulating structures;
and etching the lead superconducting thin film layer to a plurality of second insulation structures to form a control line structure and a connection structure.
According to the SQUID array-based superconducting magnetic flux excitation switch and the preparation method thereof, the loop structure, the first Josephson junction structure and the second Josephson junction structure form the main structure of the SQUID loop. Each loop structure is a communicated loop formed by sequentially connecting a plurality of curves end to end.
The first superconducting thin film structure of each of the first josephson junction structures is disposed at a first end of the loop structure. The first superconducting thin film structure of each of the second josephson junction structures is disposed at a second end of the loop structure. At this time, the loop structure is an unclosed loop having a first end and a second end. And connecting the first superconducting thin film structure of the first Josephson junction structure with the first superconducting thin film structure of the second Josephson junction structure through the loop structure, so that a series inductance structure is formed in the SQUID loop. Therefore, when a magnetic flux is obtained, the SQUID loop changes to be integral multiple of the magnetic flux quantum phi 0, and the V-phi 0 curve (the period is phi 0) cannot be changed at all, so that the phase offset of the SQUID loop can be effectively avoided, and the problem of phase offset caused by a parallel inductance structure is solved. Meanwhile, the series inductance structure formed in the SQUID loop has smaller inductance and smaller size, so that the regulation and control of the superconducting magnetic flux excitation switch are facilitated, and the SQUID loop is more compact.
The SQUID loop formed by one loop structure, one first Josephson junction structure and one second Josephson junction structure adopts a first-order gradient simple structure, and is beneficial to counteracting external parallel magnetic field interference.
And the second superconducting thin film structure of the first Josephson junction structure and the second superconducting thin film structure of the second Josephson junction structure are respectively connected through the negative electrode connection structure. At this time, it is also understood that the second superconducting thin film structure of the first josephson junction structure and the second superconducting thin film structure of the second josephson junction structure are connected through the negative electrode connection structure. Further, the negative electrode connection structure, the first josephson junction structure, the second josephson junction structure, and the loop structure form a main structure of a SQUID loop in which two josephson junctions are connected in parallel.
And the cathode connecting structure corresponding to one loop structure is connected with the anode connecting structure corresponding to the adjacent loop structure, so that a plurality of SQUID loops are connected in series to form a superconducting magnetic flux excitation switch based on the SQUID array.
Therefore, the SQUID array-based superconducting magnetic flux excitation switch has smaller inductance and size, so that the SQUID loop is more compact, the switch regulation is facilitated, and the phase offset of the SQUID loop can be effectively avoided.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a superconducting magnetic flux excitation switch based on a SQUID array provided in an embodiment.
Fig. 2 is a schematic structural diagram of a superconducting magnetic flux excitation switch based on a SQUID array provided in an embodiment.
Fig. 3 is a schematic structural diagram of a superconducting magnetic flux excitation switch based on a SQUID array provided in an embodiment.
Figure 4 is a cross-sectional schematic diagram of a SQUID loop provided in an embodiment.
Figure 5 is a cross-sectional schematic diagram of a SQUID loop array provided in an embodiment.
Description of reference numerals:
the superconducting magnetic flux excitation switch based on the SQUID array comprises a SQUID array 100, a loop structure 20, a first Josephson junction structure 510, a second Josephson junction structure 520, a positive electrode connection structure 710, a negative electrode connection structure 720, a control line structure 30, a first structure 210, a second structure 220, a port connection structure 212, a terminal resistor 610, a resistor connection structure 611, a substrate 10, a silicon dioxide thin film 110, a second superconducting thin film structure 120, a first insulation structure 130, a first superconducting thin film structure 160, a second superconducting thin film structure 120, a connection through hole 140, a second insulation structure 150 and a terminal resistor 610.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it can be directly on, adjacent to, connected or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, doping types and/or sections, these elements, components, regions, layers, doping types and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, doping type or section from another element, component, region, layer, doping type or section. Thus, a first element, component, region, layer, doping type or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application; for example, the first doping type may be made the second doping type, and similarly, the second doping type may be made the first doping type; the first doping type and the second doping type are different doping types, for example, the first doping type may be P-type and the second doping type may be N-type, or the first doping type may be N-type and the second doping type may be P-type.
Spatial relational terms, such as "under," "below," "under," "over," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "under" and "under" can encompass both an orientation of above and below. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations) and the spatial descriptors used herein interpreted accordingly.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, in this specification, the term "and/or" includes any and all combinations of the associated listed items.
Embodiments of the application are described herein with reference to cross-sectional views that are schematic illustrations of idealized embodiments (and intermediate structures) of the application, such that variations from the shapes shown are to be expected due to, for example, manufacturing techniques and/or tolerances. Thus, embodiments of the present application should not be limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing techniques. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present application.
Referring to fig. 1, the present application provides a superconducting magnetic flux actuated switch 100 based on a SQUID array. The SQUID array based superconducting magnetic flux excitation switch 100 includes a plurality of loop structures 20, a plurality of first josephson junction structures 510, a plurality of second josephson junction structures 520, a plurality of positive pole connection structures 710, and a plurality of negative pole connection structures 720.
Each of the loop structures 20 has a first end and a second end. The first superconducting thin film structure of each of the first josephson junction structures 510 is disposed at a first end of the loop structure 20. The first superconducting thin film structure of each of the second josephson junction structures 520 is disposed at a second end of the loop structure 20. Each of the positive connection structures 710 is connected to a first end of the loop structure 20. Each of the negative electrode connection structures 720 is connected to the second superconducting thin film structure of the first josephson junction structure 510 and the second superconducting thin film structure of the second josephson junction structure 520, respectively. The negative connection structure 720 corresponding to one loop structure 20 is connected to the positive connection structure 710 corresponding to an adjacent loop structure 20.
In this embodiment, the loop structure 20 is a superconducting thin film material. One said loop structure 20, one said first josephson junction structure 510 and one said second josephson junction structure 520 form the main structure of the SQUID loop. Each loop structure 20 is a connected loop formed by connecting a plurality of curves end to end in sequence.
The first superconducting thin film structure of each of the first josephson junction structures 510 is disposed at a first end of the loop structure 20. The first superconducting thin film structure of each of the second josephson junction structures 520 is disposed at a second end of the loop structure 20. At this point, the loop structure 20 is an open loop having a first end and a second end. The first superconducting thin film structure of the first josephson junction structure 510 and the first superconducting thin film structure of the second josephson junction structure 520 are connected by the loop structure 20, so that a series inductance structure is formed in the SQUID loop. Therefore, when a magnetic flux is obtained, the SQUID loop changes to be integral multiple of the magnetic flux quantum phi 0, and the V-phi 0 curve (the period is phi 0) cannot be changed at all, so that the phase offset of the SQUID loop can be effectively avoided, and the problem of phase offset caused by a parallel inductance structure is solved. Meanwhile, the series inductance structure formed in the SQUID loop has smaller inductance and smaller size, so that the regulation and control of the superconducting magnetic flux excitation switch are facilitated, and the SQUID loop is more compact.
The SQUID loop formed by one of the loop structures 20, one of the first josephson junction structures 510 and one of the second josephson junction structures 520 adopts a first-order gradient simple structure, which is beneficial to counteracting the external parallel magnetic field interference.
And, the second superconducting thin film structures of the first and second josephson junction structures 510 and 520 are connected through the negative electrode connection structure 720, respectively. At this time, it can be understood that the second superconducting thin film structure of the first josephson junction structure 510 and the second superconducting thin film structure of the second josephson junction structure 520 are connected through the negative electrode connection structure 720. Further, the negative electrode connection structure 720, the first josephson junction structure 510, the second josephson junction structure 520 and the loop structure 20 form the main structure of a SQUID loop in which two josephson junctions are connected in parallel.
The negative connection 720 of one loop structure 20 is connected to the positive connection 710 of an adjacent loop structure 20 such that a plurality of SQUID loops are connected in series to form a SQUID array based superconducting flux actuated switch 100.
Therefore, the superconducting magnetic flux excitation switch 100 based on the SQUID array has smaller inductance and size, so that the SQUID loop is more compact, the switch regulation is facilitated, and the phase shift of the SQUID loop can be effectively avoided.
In one embodiment, the SQUID array based superconducting magnetic flux actuated switch 100 further comprises a control line structure 30. The control line structure 30 is disposed on the surfaces of the plurality of loop structures 20 in an insulated manner, and the control line structure 30 is used for inputting magnetic flux.
In this embodiment, the control line structure 30 is made of a superconducting thin film material. The control line structure 30 is disposed on the surface of a plurality of loop structures 20, forming an overlapped coupling structure. The upper and lower overlapping coupling structures of the control line structure 30 and the loop structure 20 enable the coupling of the control line structure 30 and the SQUID loop to be more matched, the coupling structure is simple, and the coupling coefficient is increased. At the same time, the control line structure 30 is used for inputting magnetic flux. The control line structure 30 and the SQUID loop are independent of each other by providing insulation to separate the structures from each other to avoid cross talk of the circulating currents between each other.
The control line structure 30 is used for inputting magnetic flux. When the input magnetic flux of the control line structure 30 is an integral multiple of the magnetic flux quantum phi 0, the superconducting magnetic flux excitation switch 100 based on the SQUID array is in a superconducting state, and the SQUID loop connected in parallel with the superconducting magnetic flux excitation switch is in a short circuit; when the input magnetic flux of the control line structure 30 is half integer multiple of the magnetic flux quantum Φ 0, the superconducting magnetic flux excitation switch 100 based on the SQUID array is in a resistance state, and the SQUID loop connected in parallel with the superconducting magnetic flux excitation switch is conducted. Thus, selective opening and closing of the SQUID loop can be achieved by the SQUID array based superconducting magnetic flux excitation switch 100.
Referring to fig. 2, in one embodiment, each of the loop structures 20 includes a first structure 210 and a second structure 220. One end of the first structure 210 is connected to the first superconducting thin film structure of the first josephson junction structure 510. The other end of the first structure 210 is connected to one end of the second structure 220. The other end of the second structure 220 is connected to the first superconducting thin film structure of the second josephson junction structure 520.
In this embodiment, the first structure 210 and the second structure 220 are shown as the bottom gray area in fig. 2 (or fig. 1) (or the loop marked by the white line in fig. 2). The second structure 220 is connected to the first structure 210 end-to-end to form a connection loop having a first end and a second end. Meanwhile, the first superconducting thin film structure of each of the first josephson junction structures 510 is disposed at one end of the first structure 210. The first superconducting thin film structure of each of the second josephson junction structures 520 is disposed at the other end of the second structure 220. At this time, it can be understood that the first and second structures 210 and 220 are underlying superconducting thin films of the first and second josephson junction structures 510 and 520. Therefore, the first josephson junction structure 510 and the bottom layer superconducting thin film of the second josephson junction structure 520 are connected through the loop structure 20, so as to form a series inductance structure, and the phase shift of the SQUID loop can be effectively avoided.
In one embodiment, the control line structure 30 is disposed on the surface of the second structure 220 in an insulated manner.
In this embodiment, the control line structure 30 is disposed on the second structure 220, so that the loop structure 20 is disposed close to one side thereof, and the loop structure 20 does not need to be disposed on the whole structure thereof, so that the coupling structure is simple. Meanwhile, the control line structure 30 is disposed away from the first josephson junction structure 510 and the second josephson junction structure 520, which is advantageous for controlling the magnetic flux signal.
The control line structure 30 is used for inputting magnetic flux. At this time, the control line structure 30 and the SQUID loop are independent from each other by providing insulation to separate the structures from each other and to prevent crosstalk of current flowing therebetween.
Referring to fig. 2, in one embodiment, the other end of the first structure 210 is connected to one end of the second structure 220 through a port connection structure 212. And the port connecting structure 212 is disposed on the surface of the first structure 210 and the surface of the second structure 220.
In this embodiment, the port connection structure 212 is connected to the other end of the first structure 210 and one end of the second structure 220, respectively. The other overlapping portion of the port connection structure 212 and the second structure 220 is an insulation (i.e. the middle portion of the loop structure 20 contacting the port connection structure 212 in fig. 2) to avoid crosstalk of flowing current.
At this point, the first structure 210 is connected in series with the second structure 220 via the port connection structure 212, forming the loop structure 20 having a first end and a second end. The first superconducting thin film structure of the first josephson junction structure 510 is connected to the first end. The first superconducting thin film structure of the second josephson junction structure 520 is connected to the second terminal to form a series inductor structure.
In one embodiment, the loop structures 20 are symmetrically disposed about the port connection structure 212.
In this embodiment, when the loop structure 20 is energized with current, the port connection structures 212 are symmetrically disposed, so that interference caused by external parallel magnetic fields can be mutually cancelled, and interference generated in the detection process can be avoided.
Referring to fig. 3, in one embodiment, the SQUID array based superconducting magnetic flux actuated switch 100 further comprises a plurality of termination resistors 610. Each of the termination resistors 610 is connected in parallel with the first josephson junction structure 510 and the second josephson junction structure 520.
In this embodiment, the termination resistor 610 is used to transition the josephson junction from an underdamped junction to an overdamped junction. The first josephson junction structure 510, the second josephson junction structure 520 and the termination resistor 610 form a parallel connection structure with each other. At this time, it can be understood that the first josephson junction structure 510 and the second josephson junction structure 520 are connected in parallel. The first josephson junction structure 510 is connected in parallel with the termination resistor 610. The second josephson junction structure 520 is connected in parallel with the termination resistor 610.
In one embodiment, the SQUID array based superconducting magnetic flux excitation switch 100 further comprises a resistive connection structure 611. One end of the resistor connection structure 611 is connected to the second superconducting thin film structure of the second josephson junction structure 520. The other end of the resistor connecting structure 611 is connected to one end of the termination resistor 610. The other end of the termination resistor 610 is connected to the positive connection structure 710.
In this embodiment, one end of the resistive connection structure 611 is connected to the second superconducting thin film structure 120 (upper Nb film) of the second josephson junction structure 520. Meanwhile, the second superconducting thin film structure 120 (upper Nb film) of the first josephson junction structure 510 is connected to the second superconducting thin film structure 120 (upper Nb film) of the second josephson junction structure 520, so that one end of the resistive connection structure 611 is also connected to the second superconducting thin film structure 120 (upper Nb film) of the first josephson junction structure 510.
The other end of the resistor connecting structure 611 is connected to one end of the termination resistor 610. The other end of the termination resistor 610 is connected to the positive connection structure 710. The positive connection structure 710 is connected to a first end of the loop structure 20. A first end of the loop structure 20 is connected to the first superconducting thin film structure 160 (lower Nb film) of the first josephson junction structure 510. Thus, the other end of the termination resistor 610 is connected to the first superconducting thin film structure 160 (lower Nb film) of the first josephson junction structure 510. Meanwhile, the first superconducting thin film structure 160 (lower Nb film) of the first josephson junction structure 510 and the first superconducting thin film structure 160 (lower Nb film) of the second josephson junction structure 520 are connected in series through the loop structure 20. At this time, the termination resistors 610 are implemented to be connected in parallel with the first and second josephson junction structures 510 and 520, respectively.
One said loop structure 20, one said first josephson junction structure 510, one said second josephson junction structure 520, one said termination resistor 610 form a complete SQUID loop. Meanwhile, the positive electrode connection structure 710 and the negative electrode connection structure 720 realize the series connection of a plurality of SQUID loops, so as to form a SQUID array structure.
In one embodiment, the first and second josephson junction structures 510 and 520 are Nb/Al-AlOxa/Nb three-layer film structure.
In one embodiment, the SQUID array in the SQUID array-based superconducting magnetic flux excitation switch can be formed by connecting 2-100 SQUID units in series.
Referring to fig. 4 and 5 (fig. 4 illustrates a schematic cross-sectional view of a SQUID, and fig. 5 illustrates a schematic cross-sectional view of a SQUID array), in one embodiment, the present application provides a method for manufacturing a superconducting magnetic flux excitation switch based on a SQUID array, comprising:
s10, providing a substrate 10, and preparing a silicon dioxide film 110 on the surface of the substrate 10;
s20, preparing a first superconducting thin film layer, a first insulating layer and a second superconducting thin film layer on the surface of the silicon dioxide thin film 110 far away from the substrate 10 in sequence;
s30, etching the second superconducting thin film layer to the first insulating layer to form a plurality of second superconducting thin film structures 120;
s40, etching the first insulating layer to the first superconducting thin film to form a plurality of first insulating structures 130, where an area of each first insulating structure 130 is greater than an area of each second superconducting thin film structure 120;
s50, etching the first superconducting thin film layer to the silicon dioxide thin film 110 to form a plurality of loop structures 20 and a plurality of first superconducting thin film structures 160;
s60, preparing a second insulating layer on the surfaces of the silicon dioxide thin films 110, the loop structures 20, the first insulating structures 130, and the second superconducting thin film structures 120;
s70, etching the second insulating layer to the plurality of first superconducting thin film structures 160 and the plurality of second superconducting thin film structures 120, respectively, to form a plurality of connecting vias 140 and a plurality of second insulating structures 150;
s80, preparing a plurality of termination resistors 610 on the surfaces of the second insulating structures 150 between the plurality of connection vias 140;
s90, depositing a lead superconducting thin film layer on the surfaces of the plurality of connection vias 140 and the plurality of second insulation structures 150;
s100, etching the lead superconducting thin film layer to a plurality of second insulation structures 150 to form a control line structure 30 and a connection structure.
This implementationIn the example, in S20, a first superconducting thin film layer (lower Nb film) and a first insulating layer (Al — AlO) were sequentially prepared by a magnetron sputtering methodx) And a second superconducting thin film layer (upper Nb film) formed of Nb/Al-AlOxa/Nb three-layer film.
In S30 and S40, the second superconducting thin film and the first insulating layer are etched to form the second superconducting thin film structure 120 and the first insulating structure 130, respectively. In the S40, the first insulating layer is aluminum oxide (Al-AlO)x) The first insulating layer (alumina) is etched by a wet method such that the area of the first insulating structure 130 is larger than that of the second superconducting thin film structure 120. The first insulating structure 130 covers the second superconducting thin film structure 120, so that the formed Nb/Al-AlO can be ensuredxthe/Nb Josephson junction area does not leak laterally, which is beneficial to the quality stability of the Josephson junction in the SQUID loop.
In S50, the loop structure 20 and the first superconducting thin film structure 160 are the same layer of superconducting thin film. The first superconducting thin film layer is etched to form a SQUID loop electrode pattern (i.e., the loop structure 20) and a first superconducting thin film structure 160 of a josephson junction (only the first superconducting thin film structure 160 is illustrated in fig. 4 and 5). At this time, it can be understood that the first superconducting thin film structure 160 and the SQUID loop electrode pattern (i.e., the loop structure 20) are integrated, and are formed by etching the first superconducting thin film layer. The SQUID loop diagram is the loop structure 20 described in figures 1, 2, 3. The first superconducting thin film structure 160, the second superconducting thin film structure 120, and the first insulating structure 130 form a josephson junction structure.
In S70, a plurality of the connecting vias 140 are used to deposit Nb films. The first superconducting thin film structure 160 and the SQUID loop electrode pattern (i.e., the loop structure 20) are integrated, and are formed by etching the first superconducting thin film layer. The Nb film makes electrical connection to the loop structure 20 (e.g., the first end of the loop structure 20 in fig. 1) through the connection via 140 for drawing out the positive connection structure 710 in fig. 2. The Nb film can realize electrical connection with the second superconducting thin film structure 120 (upper Nb film of josephson junction) through the connection via 140 for drawing out the negative connection structure 720 in fig. 1. Meanwhile, the second insulating structure 150 can achieve the isolation and insulation function between the overlapped structures in fig. 1. In S80, termination resistor 610 is disposed proximate to the josephson junction.
In S90, a lead superconducting thin film layer, which may be an Nb film, is deposited on the surfaces of the plurality of connection vias 140 and the second insulating structure 150. In S100, the lead superconducting thin film layer is etched to form the control line structure 30, the connection structure, and the like. The connection structure may be the connection structure mentioned in the above embodiments, such as the positive connection structure 710, the negative connection structure 720, the first port connection structure 212, the resistance connection structure 611, and the like shown in fig. 1 to 3.
Therefore, by the method for manufacturing the superconducting magnetic flux excitation switch based on the SQUID array, the area of each first insulating structure 130 is larger than the area of each second superconducting thin film structure 120, so that no side leakage of a josephson junction region can be ensured, and the quality stability of the josephson junction in the SQUID is facilitated. Meanwhile, the superconducting magnetic flux excitation switch 100 based on the SQUID array is prepared by the preparation method of the superconducting magnetic flux excitation switch based on the SQUID array, so that the external parallel magnetic field interference can be effectively counteracted, and the phase offset of a SQUID loop can be effectively avoided.
In one embodiment, the thickness of the silicon dioxide thin film 110 is 100nm to 1000 nm. The thickness of the first superconducting thin film structure 160 (lower layer Nb film) is 100nm to 500 nm. The first insulating structure 130 (AlO)x) The thickness of (A) is 5nm to 30 nm. The thickness of the second superconducting thin film structure 120 (upper Nb film) is 100nm to 500 nm. The thickness of the second insulating structure 150 is 200nm to 600 nm. The thickness of the terminal resistor 610(PdAu thin film) is 50 nm-500 nm. The thickness of the deposited lead superconducting thin film layer (Nb thin film) is 300 nm-800 nm.
In one embodiment, the Nb/Al-AlO is prepared by adopting a magnetron sputtering methodxAlO in case of a/Nb trilayer filmxThe oxidation pressure of the film is 100 mTorr-5000 mTorr, the oxidation time is 2-24 hours. The Josephson junction region (the second superconducting thin film structure 120) has an area of 1 μm2～100μm2。
Specifically, in one embodiment, the SQUID array based superconducting magnetic flux actuated switch consists of 7 SQUID loops connected in series. The preparation method of the superconducting magnetic flux excitation switch based on the SQUID array comprises the following steps:
growing SiO with the thickness of 100nm2Preparing Nb/Al-AlO on 2-inch monocrystal high-resistance silicon wafer 10 of film 110 by magnetron sputtering methodxThe thickness of the/Nb three-layer film is respectively 100nm, 5nm and 100 nm. Wherein, the Al film is prepared by using the oxidation gas pressure of 100mTorr and the oxidation time of 5 hours.
Performing first photoetching on the basis of the steps, and etching the upper Nb film to obtain the Nb film with the area of 1 mu m2The second superconducting thin film structure 120.
Performing second photoetching on the basis of the steps, and etching the Al-AlO in the interlayer by adopting wet etchingxFilm of Al-AlOxAnd (4) forming a structure 130 to obtain a Josephson junction region interlayer pattern. Wherein, Al-AlOxThe area of the structure 130 is larger than that of the upper pattern 120.
And carrying out third photoetching on the basis of the steps, and etching the Nb film at the lowest layer to obtain the SQUID loop pattern.
On the basis of the steps, the SiO with the thickness of 200nm is grown by adopting a low-temperature chemical vapor deposition method2A thin film is etched, and then a third photoetching is carried out, and SiO is etched2And (5) thin film forming, so as to obtain a through hole connection structure 140 of the Nb wire layer and the Nb film at the lower layer. The remaining SiO2The thin film is the second insulating structure 150.
On the basis of the steps, fourth photoetching is carried out, a PdAu thin film with the thickness of 150nm is prepared by adopting an electron beam evaporation method to serve as a resistance layer, and the PdAu resistance 610 is obtained by stripping.
On the basis of the steps, a 300nm thick Nb film is deposited by adopting a magnetron sputtering method, then fifth photoetching is carried out, and the Nb film is etched, so that the control line structure 30 and the connection structure pattern are obtained.
On the basis of the steps, 2-inch samples are subjected to scribing, and the superconducting magnetic flux excitation switch based on the SQUID array is obtained.
In one embodiment, a superconducting flux actuated switch based on a SQUID array comprises 30 SQUID loops connected in series. The preparation method of the superconducting magnetic flux excitation switch based on the SQUID array comprises the following steps:
growing SiO with the thickness of 1000nm2Preparing Nb/Al-AlO on 2-inch monocrystal high-resistance silicon wafer 10 of film 110 by magnetron sputtering methodxThe thickness of the/Nb three-layer film is respectively 500nm, 30nm and 500 nm. Wherein the Al film is prepared under an oxidation pressure of 5000mTorr and an oxidation time of 24 hours.
Performing first photoetching on the basis of the steps, and etching the upper Nb film to obtain the Nb-based film with the area of 100 mu m2The second superconducting thin film structure 120.
Performing second photoetching on the basis of the steps, and etching the Al-AlO in the interlayer by adopting wet etchingxFilm of Al-AlOxStructure 130. Wherein, Al-AlOxThe area of the structure 130 is larger than that of the upper pattern 120.
And carrying out third photoetching on the basis of the steps, and etching the Nb film at the lowest layer to obtain the SQUID loop pattern.
On the basis of the steps, growing SiO with the thickness of 600nm by adopting a low-temperature chemical vapor deposition method2A thin film is etched, and then a third photoetching is carried out, and SiO is etched2And (5) thin film forming, so as to obtain a through hole connection structure 140 of the Nb wire layer and the Nb film at the lower layer. The remaining SiO2The thin film is the second insulating structure 150.
On the basis of the steps, fourth photoetching is carried out, a PdAu film with the thickness of 500nm is prepared by adopting an electron beam evaporation method to be used as a resistance layer, and the PdAu resistance 610 is obtained by stripping.
On the basis of the steps, an Nb film with the thickness of 800nm is deposited by adopting a magnetron sputtering method, then fifth photoetching is carried out, and the Nb film is etched, so that a control line structure 30 and a connection structure pattern are obtained.
On the basis of the steps, 2-inch samples are subjected to scribing, and the superconducting magnetic flux excitation switch based on the SQUID array is obtained.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features of the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. A superconducting magnetic flux excitation switch based on a SQUID array, comprising a plurality of loop structures (20), a plurality of first josephson junction structures (510), a plurality of second josephson junction structures (520), a plurality of positive connection structures (710), and a plurality of negative connection structures (720);
each loop structure (20) having a first end and a second end;
a first superconducting thin film structure of each of the first josephson junction structures (510) disposed at a first end of the loop structure (20);
a first superconducting thin film structure of each of the second josephson junction structures (520) disposed at a second end of the loop structure (20);
each positive connection structure (710) is connected to a first end of the loop structure (20);
each of the negative connection structures (720) is connected to a second superconducting thin film structure of the first josephson junction structure (510) and a second superconducting thin film structure of the second josephson junction structure (520), respectively;
the negative electrode connecting structure (720) corresponding to one loop structure (20) is connected with the positive electrode connecting structure (710) corresponding to the adjacent loop structure (20).
2. The SQUID array based superconducting magnetic flux excitation switch of claim 1, wherein the SQUID array based superconducting magnetic flux excitation switch further comprises:
and the control line structure (30) is arranged on the surfaces of the loop structures (20) in an insulating mode, and the control line structure (30) is used for inputting magnetic flux.
3. A SQUID array based superconducting magnetic flux excitation switch according to claim 2, wherein each of the loop structures (20) comprises a first structure (210) and a second structure (220), the first structure (210) being connected at one end to the first superconducting thin film structure of the first josephson junction structure (510), the first structure (210) being connected at the other end to one end of the second structure (220), the second structure (220) being connected at the other end to the first superconducting thin film structure of the second josephson junction structure (520).
4. The SQUID array based superconducting flux excitation switch of claim 3, wherein said control line structure (30) is insulatively disposed on a surface of said second structure (220).
5. The SQUID array-based superconducting flux excitation switch of claim 3, wherein the other end of the first structure (210) is connected to one end of the second structure (220) through a port connection structure (212), and the port connection structure (212) is disposed on a surface of the first structure (210) and a surface of the second structure (220).
6. The SQUID array-based superconducting flux excitation switch of claim 5, wherein the loop structure (20) is symmetrically disposed about the port connection structure (212).
7. The SQUID array based superconducting magnetic flux excitation switch of claim 1, wherein the SQUID array based superconducting magnetic flux excitation switch further comprises a plurality of termination resistors (610);
each of the termination resistances (610) is connected in parallel with the first and second josephson junction structures (510, 520).
8. The SQUID array based superconducting magnetic flux excitation switch of claim 7, further comprising a resistive connection structure (611);
one end of the resistor connecting structure (611) is connected with the second superconducting thin film structure of the second Josephson junction structure (520), and the other end of the resistor connecting structure (611) is connected with one end of the termination resistor (610);
the other end of the terminal resistor (610) is connected with the anode connecting structure (710).
9. The SQUID array-based superconducting flux excitation switch of claim 1, wherein the first and second josephson junction structures (510, 520) are Nb/Al-AlOxa/Nb three-layer film structure.
10. A preparation method of a superconducting magnetic flux excitation switch based on a SQUID array is characterized by comprising the following steps:
s10, providing a substrate (10), and preparing a silicon dioxide film (110) on the surface of the substrate (10);
s20, preparing a first superconducting thin film layer, a first insulating layer and a second superconducting thin film layer on the surface of the silicon dioxide thin film (110) far away from the substrate (10) in sequence;
s30, etching the second superconducting thin film layer to the first insulating layer to form a plurality of second superconducting thin film structures (120);
s40, etching the first insulating layer to the first superconducting thin film layer to form a plurality of first insulating structures (130), wherein the area of each first insulating structure (130) is larger than that of each second superconducting thin film structure (120);
s50, etching the first superconducting thin film layer to the silicon dioxide thin film (110) to form a plurality of loop structures (20) and a plurality of first superconducting thin film structures (160);
s60, preparing second insulating layers on the surfaces of the silicon dioxide thin films (110), the surfaces of the loop structures (20), the surfaces of the first insulating structures (130), and the surfaces of the second superconducting thin film structures (120);
s70, etching the second insulating layer to a plurality of first superconducting thin film structures (160) and a plurality of second superconducting thin film structures (120) respectively to form a plurality of connecting through holes (140) and a plurality of second insulating structures (150);
s80, preparing a plurality of terminal resistors (610) on the surfaces of the second insulating structures (150) among the connecting through holes (140);
s90, depositing lead superconducting thin film layers on the surfaces of the connecting through holes (140) and the second insulating structures (150);
s100, etching the lead superconducting thin film layer to a plurality of second insulation structures (150) to form a control line structure (30) and a connection structure.
CN202011181251.6A 2020-10-29 2020-10-29 Superconducting magnetic flux excitation switch based on SQUID array and preparation method thereof Pending CN112289920A (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020190381A1 (en) * 2001-06-15 2002-12-19 Herr Quentin P. Capacitor for signal propagation across ground plane boundaries in superconductor integrated circuits
CN109755379A (en) * 2017-11-24 2019-05-14 中国科学院物理研究所 The device of realization Topological Quantum bit and corresponding preparation method

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020190381A1 (en) * 2001-06-15 2002-12-19 Herr Quentin P. Capacitor for signal propagation across ground plane boundaries in superconductor integrated circuits
CN109755379A (en) * 2017-11-24 2019-05-14 中国科学院物理研究所 The device of realization Topological Quantum bit and corresponding preparation method

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