A three-dimensional packaged superconducting quantum bit device, its preparation method and equipment

Abstract

The present invention provides a three-dimensional packaged superconducting qubit device. The niobium-based superconducting qubit device is sequentially arranged from bottom to top as follows: a lower substrate, a first superconducting thin film, metal pillars, a second superconducting thin film, and an upper substrate. The preparation method and equipment thereof are also provided. The three-dimensional packaged superconducting qubit device of the present invention avoids the disadvantages of aluminum-based qubit samples, where alloying between aluminum materials and indium pillars forms a non-superconducting layer, making it difficult to achieve superconducting connections. It simplifies the process steps and realizes three-dimensional superconducting connections. The superconducting critical current obtained by series testing of multiple welding points reaches 100 mA, which is much larger than the critical current of 30 mA for aluminum-based flip-chip devices. The device preparation process is simple and the performance is stable. Due to the superconducting connection between the superconducting material niobium and indium, a large current can be applied at the connection without causing phenomena such as heating, which helps to achieve three-dimensional manipulation of the superconducting qubit device. The short interconnects of the flip chip reduce inductance, resistance, and capacitance, and the signal integrity and frequency characteristics are better.

Description

Technical Field

[0001] The present invention belongs to the field of quantum devices, and particularly relates to a three-dimensional packaged superconducting qubit device, a preparation method thereof, and a device therefor. Background Art

[0002] Quantum computing, by virtue of the characteristics such as superposition and entanglement of quantum states, has an exponential acceleration effect relative to classical computers when solving certain problems. In recent years, great progress has been made in the research of quantum computing based on superconducting circuits, and its advantages of good scalability and easy controllability have attracted the research interest of many scientific research institutions. In the next few years, a superconducting quantum computing prototype machine may integrate more than 50 synchronously controllable qubits and may surpass classical computers in issues with great practical value such as quantum simulation and optimization.

[0003] However, with the increase in the number of qubits, the connections of the original in-plane resonators, SQUIDs, and measurement leads will no longer meet the increasing test requirements. The three-dimensional packaging technology can reduce the connection distance, reduce the influence of parasitic capacitance and inductance, and improve the packaging density, which is a key step in the development of multi-qubit superconducting quantum devices. The current existing technology has realized a three-dimensional flip-chip connection structure on an aluminum-based qubit sample. However, due to the alloying between the aluminum film and the indium pillars required for flip-chip connection, it is necessary to add an isolation layer of TiN between the aluminum film and indium. This step increases the complexity of the process. Poor interface treatment of different materials is likely to form a non-superconducting connection, which limits the magnitude of the superconducting current that can be applied, thereby affecting the performance of the device. There is an urgent need to provide a superconducting connection device for three-dimensional packaging that overcomes the alloying between aluminum materials and indium pillars, forms a non-superconducting alloy layer, and is difficult to achieve superconducting connection, and simplifies the process steps. Summary of the Invention

[0004] Therefore, the purpose of the present invention is to overcome the defects in the prior art and provide a three-dimensional packaged superconducting qubit device, a preparation method thereof, and a device therefor. The present invention uses a superconducting niobium film as the material for the resonator, capacitor, and electrode. Indium pillars required for cold pressure welding are evaporated on the niobium film. Finally, the upper and lower chips are welded and pressed together by a flip-chip instrument to achieve a three-dimensional packaging with superconducting connection.

[0005] To achieve the above purpose, the first aspect of the present invention provides that the niobium-based superconducting qubit device is sequentially arranged from bottom to top as: a lower substrate, a first superconducting thin film, metal pillars, a second superconducting thin film, and an upper substrate; wherein,

[0006] the first superconducting thin film includes a resonator, a transmission line, and an electrode; and

[0007] the second superconducting thin film includes a capacitor and a Josephson junction;

[0008] Preferably, both the resonant cavity and the capacitor are fabricated by microfabrication.

[0009] For the three-dimensional packaged superconducting qubit device according to the first aspect of the present invention, wherein the materials of the lower substrate and the upper substrate are selected from one or more of the following: sapphire, high-resistivity silicon, amorphous silicon, preferably sapphire or high-resistivity silicon, and most preferably sapphire;

[0010] The materials of the first superconducting thin film and the second superconducting thin film are selected from one or more of the following: niobium-based superconducting materials, tantalum-based superconducting materials, TiN-based superconducting materials, NbN-based superconducting thin films, NbTiN-based superconducting thin films, preferably niobium-based superconducting thin films, tantalum-based superconducting thin films, titanium nitride superconducting thin films, and most preferably niobium-based superconducting thin films; and / or

[0011] The metal posts are indium posts or lead-tin posts, and most preferably indium posts;

[0012] Preferably, the materials of the resonant cavity, the transmission line, the electrode and the capacitor are selected from one or more of the following: niobium-based superconducting materials, tantalum-based superconducting materials, TiN-based superconducting materials, NbN-based superconducting thin films, NbTiN-based superconducting thin films, preferably niobium-based superconducting materials, tantalum-based superconducting materials, titanium nitride superconducting materials, and most preferably niobium-based superconducting materials; and / or

[0013] Preferably, the material of the Josephson junction is an Al-based superconducting material or an Nb-based superconducting material, and most preferably an Al-based superconducting material.

[0014] For the three-dimensional packaged superconducting qubit device according to the first aspect of the present invention, wherein when the materials of the resonant cavity, the capacitor and the electrode are all niobium-based superconducting materials and the metal posts are indium posts, a superconducting material Nb3In is formed by reaction at the connection between the niobium-based superconducting material and the indium posts;

[0015] Preferably, the connection between the niobium-based superconducting material and the indium posts is a superconducting connection.

[0016] The second aspect of the present invention provides a method for fabricating the three-dimensional packaged superconducting qubit device described in the first aspect, and the method includes the following steps:

[0017] (1) Clean the upper substrate and the lower substrate, and grow a niobium metal thin film on the upper substrate and / or the lower substrate;

[0018] (2) Perform photolithography and development on the surface of the sample obtained in step (1);

[0019] (3) Etch and remove the photoresist from the sample developed in step (2) to obtain the upper substrate and the lower substrate after photoresist removal;

[0020] (4) Fabricate a Josephson junction on the upper substrate after removing the photoresist obtained in step (3);

[0021] (5) Perform photolithography and development on the surfaces of the lower substrate prepared in step (3) and the upper substrate obtained in step (4);

[0022] (6) Grow metal pillars on the sample obtained in step (5), and remove the photoresist by stripping to obtain the upper substrate and the lower substrate;

[0023] (7) Align and press-weld the upper substrate and the lower substrate obtained in step (6) to obtain the three-dimensional packaged superconducting qubit device;

[0024] Preferably, in step (3), the etching method is selected from one or more of the following: reactive ion etching, chemical etching, and more preferably reactive ion etching;

[0025] More preferably, step (3) further includes a step of removing the photoresist from the etched sample.

[0026] According to the method of the second aspect of the present invention, wherein step (1) further includes the following steps: Immerse the upper substrate and the lower substrate in a solvent, perform ultrasonic cleaning, and blow the upper substrate and the lower substrate with nitrogen after the ultrasonic cleaning ends;

[0027] Preferably, the solvent is acetone or isopropyl alcohol;

[0028] Preferably, the power of the ultrasonic wave is 50 - 100 W, and more preferably 90 W;

[0029] Preferably, the time of the ultrasonic wave is 1 - 30 minutes, and more preferably 10 minutes;

[0030] Preferably, the thickness of the niobium metal thin film is 50 - 200 nm, and more preferably 80 - 150 nm; and / or

[0031] Preferably, the method for growing the niobium metal thin film is magnetron sputtering or electron beam evaporation, and more preferably magnetron sputtering.

[0032] According to the method of the second aspect of the present invention, wherein step (2) further includes the following steps:

[0033] (A) Spin-coat a photoresist on the surface of the sample obtained in step (2) and bake it on a hot plate;

[0034] (B) Perform laser direct writing on the sample with the spin-coated photoresist to expose the designed pattern;

[0035] (C) Develop and fix the sample after exposure, and blow the substrate with nitrogen after the fixing is completed;

[0036] Preferably, in the step (A), the thickness of the photoresist is 1.0 to 4.8 microns, preferably 1.3 microns; and / or

[0037] Preferably, in the step (A), the photoresist is S1813 photoresist or SPR220 photoresist, and most preferably S1813 photoresist.

[0038] According to the method of the second aspect of the present invention, wherein the step (4) further includes the following steps:

[0039] (a) Clean the sample obtained in step (3), and spin-coat MAA photoresist, PMMA photoresist and SX AR-PC conductive adhesive thereon in sequence;

[0040] (b) Electron beam expose the Josephson junction pattern on the sample obtained in step (a);

[0041] (c) Develop and fix the exposed sample, and blow the substrate with nitrogen after fixing;

[0042] (d) Put the sample obtained in step (c) into Plassys-MEB550s to prepare a Josephson junction;

[0043] (e) Remove the photoresist and strip the sample obtained in step (e) to obtain the niobium-based planar multi-superconducting qubit;

[0044] Preferably, in the step (a), the thickness of the MAA photoresist is preferably 80 to 400 nm, more preferably 150 to 250 nm, and most preferably 200 nm: and / or the thickness of the PMMA photoresist is preferably 100 to 400 nm, and most preferably 200 nm.

[0045] According to the method of the second aspect of the present invention, wherein the step (5) further includes the following steps:

[0046] (f) Spin-coat photoresist on the surface of the sample obtained in step (4) and bake on a hot plate;

[0047] (g) Laser direct write on the sample with spin-coated photoresist to expose the designed pattern;

[0048] (h) Develop and fix the exposed sample, and blow the substrate with nitrogen after fixing;

[0049] Preferably, in the step (f), the thickness of the photoresist is 5 to 15 microns, more preferably 5 to 10 microns, and most preferably 8 microns; and / or the photoresist is AZ P4620 photoresist or SPR220 photoresist, and most preferably AZ P4620 photoresist.

[0050] According to the method of the second aspect of the present invention, in the step (6), the film thickness of the metal pillar is 5-10 μm, preferably 7 μm, and / or the method for growing the indium metal film is selected from one or more of the following: thermal evaporation, electron beam evaporation, magnetron sputtering, and most preferably thermal evaporation; and / or

[0051] In the step (7), the pressure welding pressure is 10-30 N / mm 2 , preferably 15 N / mm 2 ; and / or the pressure welding method is cold pressure welding or hot pressure welding, preferably cold pressure welding.

[0052] The third aspect of the present invention provides a quantum computing device based on a superconducting circuit, which includes the three-dimensional packaged superconducting qubit device of the first aspect or the three-dimensional packaged superconducting qubit device prepared by the method of the second aspect.

[0053] The three-dimensional packaged superconducting qubit device of the present invention can have, but is not limited to, the following beneficial effects:

[0054] 1. The three-dimensional packaged superconducting qubit device of the present invention avoids the drawbacks of the aluminum-based qubit sample, where alloying between the aluminum material and the indium pillar forms a non-superconducting layer, making it difficult to achieve superconducting connection. It simplifies the process steps and realizes three-dimensional superconducting connection.

[0055] 2. For the three-dimensional packaged superconducting qubit device of the present invention, when multiple welding points are tested in series, the superconducting critical current reaches 100 mA, which is much larger than the 30 mA critical current of the aluminum-based flip-chip bonded device. The device preparation process is simple and the performance is stable.

[0056] 3. Due to the superconducting connection between the superconducting material niobium and indium, a large current can be applied at the connection without causing phenomena such as heating, which helps to achieve three-dimensional manipulation of the superconducting qubit device.

[0057] 4. The short interconnection of the flip-chip reduces inductance, resistance, and capacitance, and the signal integrity and frequency characteristics are better.

[0058] 5. The three-dimensional superconducting connection is achieved between the flip-chip bonded chips, not limited to the preparation of superconducting qubit devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings, where:

[0060] Figure 1 Shows the structural diagrams of the upper and lower substrates of the three-dimensional packaged superconducting qubit device of the present invention in Example 1, where Figure 1 (a) Shows the structural diagram of the upper substrate of the three-dimensional packaged superconducting qubit device of the present invention;Figure 1 (b) shows the structural diagram of the lower substrate of the three-dimensional packaged superconducting qubit device of the present invention.

[0061] Figure 2 Shows the schematic diagram of the preparation process of the three-dimensional packaged superconducting qubit device of the present invention in Example 1.

[0062] Figure 3 Shows the side view of the upper and lower chip spacing after flip-chip bonding of the three-dimensional packaged superconducting qubit device prepared in Example 1.

[0063] Figure 4 Shows the test results of the resonator of the 6-qubit sample prepared in Example 3 in Test Example 2.

[0064] Figure 5 Shows the T1 test results of the 6-qubit sample prepared in Example 3 in Test Example 3. Detailed implementation manners

[0065] The present invention will be further described below through specific examples. However, it should be understood that these examples are only used for more detailed and specific description, and should not be construed as limiting the present invention in any form.

[0066] This part gives a general description of the materials and test methods used in the experiments of the present invention. Although many of the materials and operation methods used to achieve the purpose of the present invention are well known in the art, the present invention still describes them in as much detail as possible here. Those skilled in the art are aware that, in the context, if not otherwise specified, the materials and operation methods used in the present invention are well known in the art.

[0067] The reagents and instruments used in the following examples are as follows:

[0068] Reagents:

[0069] Sapphire substrates, acetone, isopropyl alcohol, photoresist, developer, NMP degluing agent liquid, all purchased from Suzhou Yancai Micro-Nano Technology Co., Ltd.

[0070] Instruments:

[0071] Ultra-high vacuum magnetron sputtering instrument, purchased from Wuko Optoelectronics Co., Ltd., model PVD400UHV;

[0072] Spin coater, purchased from the Institute of Microelectronics, Chinese Academy of Sciences, model KW-4A;

[0073] Laser direct writing instrument, purchased from Heidelberg Company, Germany, model DWL66+;

[0074] Reactive ion etching machine, purchased from Samco Company, model 10NR;

[0075] Electron beam lithography machine, purchased from Raith, model Raith150;

[0076] Indium evaporation equipment, purchased from Beijing Shihua Jianfeng Co., Ltd., model HYBRID-600in;

[0077] Flip-chip bonding equipment, purchased from SET Company in France, model ACCμRA100.

[0078] Example 1

[0079] This embodiment is used to illustrate the preparation method of the three-dimensional packaged superconducting qubit device of the present invention.

[0080] Figure 1 The structure diagrams of the upper and lower substrates of the three-dimensional packaged superconducting qubit device of the present invention in Embodiment 1 are shown, where Figure 1 (a) shows the structure diagram of the upper substrate of the three-dimensional packaged superconducting qubit device of the present invention, and the bit capacitor is shown as marked in the figure; Figure 1 (b) shows the structure diagram of the lower substrate of the three-dimensional packaged superconducting qubit device of the present invention, and the resonator is shown as marked in the figure. Figure 2 The process schematic diagram of the niobium-based three-dimensional packaged superconducting qubit device of the present invention in Embodiment 1 is shown.

[0081] (1) Pre-cleaning of the substrate to ensure the growth of high-quality and pure niobium metal thin film in subsequent steps.

[0082] Step 1: Place the standard 2-inch sapphire substrate in analytical pure acetone liquid and clean it with ultrasonic wave at a power of 90W for 10 minutes.

[0083] Step 2: After Step 1, use clean tweezers to pick up the standard 2-inch sapphire substrate in acetone liquid and quickly (the acetone liquid on the substrate should cover the substrate completely during this process) put it into analytical pure isopropanol liquid, and then clean it with ultrasonic wave at a power of 90W for 10 minutes.

[0084] Step 3: After Step 2, use clean tweezers to pick up the standard 2-inch sapphire substrate in isopropanol liquid and blow it continuously with high-purity nitrogen for 3 minutes to remove the surface isopropanol liquid and sundries such as dust that may fall on the standard 2-inch sapphire substrate.

[0085] (2) Growth of high-quality and pure niobium metal thin film, which lays the foundation for the subsequent preparation of the three-dimensional superconducting qubit superconducting circuit.

[0086] Step 4: After Step 3, place the clean standard 2-inch sapphire substrate on the sample holder in the pre-vacuum injection chamber of the ultra-high vacuum magnetron sputtering instrument, and then pump the pre-vacuum chamber to make its background vacuum better than 5x10 -4After reaching [[Pa]], transfer the sample to the ultra-high vacuum chamber.

[0087] Step 5: After step 4, heat the ultra-high vacuum chamber to 120 °C and bake for 3 hours, then let it cool naturally. Wait until the background vacuum in the main vacuum chamber is better than 5×10 -7 [[Pa]]. After that, close the gate valve between the main vacuum chamber and the molecular pump by 85%. Then introduce high-purity argon gas into the main vacuum chamber to make the background vacuum in the main vacuum chamber reach 0.5 [[Pa]]. After meeting the vacuum requirement, turn on the DC magnetron sputtering power supply, set the power to 120 W, and pre-sputter for 10 minutes to remove the oxide layer on the target and obtain a fresh Nb target surface. Then open the baffle between the target and the substrate and sputter for 200 s to obtain a niobium film with a thickness of about 100 nanometers.

[0088] Step 6: After step 5, stop introducing high-purity argon gas into the main vacuum chamber and open the gate valve between the main vacuum chamber and the molecular pump. Wait for 2 hours. After the sample stage temperature drops to room temperature, transfer the sample to the pre-vacuum chamber.

[0089] Step 7: After step 6, close the molecular pump and mechanical pump of the pre-vacuum chamber, open the bleed valve, introduce argon gas of ordinary purity into the pre-vacuum chamber so that the pre-vacuum chamber can be opened under atmospheric pressure, and take out the sapphire substrate with the grown niobium thin film.

[0090] (3) Lithography and development, this step is an important step in preparing the three-dimensional superconducting quantum chip.

[0091] Step 8: After step 7, place the sapphire substrate with the grown niobium thin film on a spin coater, coat S1813 photoresist, rotate at 4000 revolutions per minute, spin and homogenize the glue for 60 s, and bake at 115 °C for 1 min to form a 1.3-micron-thick S1813 photoresist layer on the substrate.

[0092] Step 9: After step 8, place the substrate coated with photoresist on a DWL66+ laser direct writing instrument and automatically expose the designed pattern with a laser power of 60 W in the light focusing mode.

[0093] Step 10: After step 9, take out the exposed substrate, develop it in ZX238 developer for 40 s, fix it in deionized water for 10 s, then take it out and dry it with high-purity nitrogen.

[0094] (4) Etching, this step is an important step in preparing the three-dimensional superconducting qubit device.

[0095] Step 11: After step 10, place the sample into the chamber of the Plasmalab 80plus reactive ion etcher. Set the SF6 gas flow rate to 30 sccm, the Ar gas flow rate to 5 sccm, the pressure to 30 mTorr, and the power to 100 W. Run a cycle program of 6 etchings for 1 minute each followed by 1 minute of cooling. After completion, introduce ordinary nitrogen gas into the etcher chamber until it reaches atmospheric pressure, and then take out the etched sample.

[0096] Step 12: After step 11, place the etched substrate into the NMP remover liquid and soak it on an 80-degree baking table for 3 hours. Then take it out and soak it in isopropyl alcohol liquid for 10 minutes, followed by ultrasonic cleaning at a power of 40 W for 1 minute. After that, take it out and dry it with dry nitrogen.

[0097] (5) Fabricate Josephson junctions on the upper chip, which is a necessary step for fabricating three-dimensional superconducting qubits.

[0098] Step 13: Place the sample of the upper chip after step 12 on a spin coater and drop MAA(8.5) photoresist. Spin at 3000 rpm for 1 minute to evenly coat the resist. Then place the substrate on a 160°C hot plate and bake for 10 minutes to uniformly coat it with MAA(8.5) photoresist.

[0099] After that, place the substrate on a spin coater and drop PMMA(A5) photoresist. Spin at 4000 rpm for 1 minute, and then place the substrate on a 160°C hot plate and bake for 10 minutes to uniformly coat it with PMMA(A5) photoresist.

[0100] After cooling the substrate for three minutes, place it on a spin coater and evenly drop SX AR-PC5000 / 90.1 high-performance conductive adhesive. Spin at 4000 rpm for 1 minute, and then place the substrate on an 110°C hot plate and bake for 2 minutes to uniformly coat it with AR-PC 5000 / 90.1 high-performance conductive adhesive.

[0101] Step 14: After step 13, place the sample in a JBX-6300FS electron beam lithography machine and perform exposure to specify the Josephson junction pattern at an acceleration voltage of 100 kV and a beam current of 500 pA.

[0102] Step 15: After step 14, take the exposed substrate and develop it in a MIBK:IPA(1:3) developer at 24°C for 50 seconds. Then immediately fix it in deionized water for 15 seconds, and then take it out and dry it with dry nitrogen.

[0103] Step 16: After step 15, put the exposed and developed sample into the Plassys-MEB550s to call the program for fabricating Josephson junctions.

[0104] Step 17: After step 16, place the knotted sample in NMP degreasing agent liquid, soak it on an 80°C baking table for 3 hours, then take it out and soak it in isopropyl alcohol liquid for 10 minutes, ultrasonically clean it at a power of 40W for 1 minute, and take it out and dry it with dry nitrogen.

[0105] Step 18: After step 17, place the substrate on a spin coater, and drop AZ-P4620 photoresist. Rotate at a speed of 500 rpm for 10 s for spin coating, then increase the speed to 1800 rpm and spin coat for 1 minute. Thereafter, place the substrate on a 110°C hot plate and bake for 3 minutes to evenly coat it with AZ-P4620 photoresist, and expose the required pattern in laser direct writing.

[0106] Step 19: After step 18, place the substrate in the vacuum chamber of a HYBRID 600In indium evaporation coating machine. After the background vacuum is better than 4x10 -3 Pa, use an ion source KDC75 to bombard at 400V and 20mA for 1 minute to remove the oxide layer on the niobium surface. Then, after the vacuum is better than 5x10 -4 Pa, thermally evaporate and coat indium. The indium coating voltage is 5V and the current is 60A, and evaporate for 30 minutes to obtain a 7um-thick indium film. Then repeat step 17 to remove the glue and dry it.

[0107] Step 20: Place the upper and lower chip samples prepared in step 19 on the upper and lower positions of an ACCμRA100 flip chip bonder respectively. Adjust the two to be parallel. After the patterns are aligned, cold press and weld the upper and lower chips at room temperature with a pressure of 2000g for 180 s. Then, after decompression and removal, obtain a three-dimensional packaged superconducting qubit sample.

[0108] Figure 3 The side view of the spacing between the upper and lower chips after flip chip bonding of the three-dimensional packaged superconducting qubit device prepared in Example 1 is shown.

[0109] The test results show that: the maximum superconducting critical current of the indium pillars welded between the upper and lower chips reaches 100 mA, which is more than twice as large as the maximum superconducting current of 30 mA between the upper and lower chips of the aluminum-based three-dimensional packaged qubit sample.

[0110] Example 2

[0111] This test example is used to illustrate the resonance cavity test results of the 6-qubit device prepared in Example 1.

[0112] The preliminary test shows that the average T1 time of the qubit sample is 10 μs - 20 μs, which basically meets the application requirements of multi-qubit superconducting quantum devices. The device quality can be further improved by improving the process in the future.

[0113] Although the present invention has been described to a certain extent, it is obvious that appropriate changes can be made to various conditions without departing from the spirit and scope of the present invention. It is understood that the present invention is not limited to the described embodiments, but falls within the scope of the claims, which include equivalent substitutions for each of the factors described.

Claims

1. A three-dimensional packaged superconducting qubit device, characterized in that, The niobium-based superconducting qubit device is arranged from bottom to top as follows: a lower substrate, a first superconducting thin film, metal pillars, a second superconducting thin film, and an upper substrate; wherein, the first superconducting thin film includes a resonator, a transmission line, and an electrode; and the second superconducting thin film includes a capacitor and a Josephson junction; the materials of the resonator, the capacitor, and the electrode are all niobium-based superconducting materials, the metal pillars are indium pillars, and a superconducting material Nb3In is formed by reaction at the connection between the niobium-based superconducting material and the indium pillars, and the connection between the niobium-based superconducting material and the indium pillars is a superconducting connection.

2. The three-dimensional packaged superconducting qubit device according to claim 1, wherein Both the resonator and the capacitor are prepared by microfabrication.

3. The three-dimensional packaged superconducting qubit device according to claim 1, wherein: the materials of the lower substrate and the upper substrate are selected from one or more of the following: sapphire, high-resistance silicon, amorphous silicon; and / or the materials of the first superconducting thin film and the second superconducting thin film are selected from one or more of the following: niobium-based superconducting materials, tantalum-based superconducting materials, TiN-based superconducting materials, NbN-based superconducting thin films, NbTiN-based superconducting thin films.

4. The three-dimensional packaged superconducting qubit device according to claim 3, wherein: the materials of the lower substrate and the upper substrate are sapphire or high-resistance silicon; and / or the materials of the first superconducting thin film and the second superconducting thin film are selected from one or more of the following: niobium-based superconducting thin films, tantalum-based superconducting thin films, titanium nitride superconducting thin films.

5. The three-dimensional packaged superconducting qubit device according to claim 4, wherein: the materials of the lower substrate and the upper substrate are sapphire; and / or the materials of the first superconducting thin film and the second superconducting thin film are niobium-based superconducting thin films.

6. The three-dimensional packaged superconducting qubit device according to any one of claims 1 to 5, wherein: the material of the Josephson junction is an Al-based superconducting material or a Nb-based superconducting material.

7. The three-dimensional packaged superconducting qubit device according to claim 6, wherein: the material of the Josephson junction is an Al-based superconducting material.

8. A method for fabricating a three-dimensional packaged superconducting qubit device according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: (1) Clean the upper substrate and the lower substrate, and grow a niobium metal thin film on the upper substrate and / or the lower substrate; (2) Perform photolithography and development on the surface of the sample obtained in step (1); (3) Etch and remove the photoresist from the sample developed in step (2) to obtain the upper substrate and the lower substrate after photoresist removal; (4) Prepare a Josephson junction on the upper substrate after photoresist removal obtained in step (3); (5) Perform photolithography and development on the surfaces of the lower substrate prepared in step (3) and the upper substrate obtained in step (4); (6) Grow metal pillars on the sample obtained in step (5), and remove the photoresist by stripping to obtain the upper substrate and the lower substrate; (7) Align and press-weld the upper substrate and the lower substrate obtained in step (6) to obtain the three-dimensional packaged superconducting qubit device.

9. The method according to claim 8, wherein In step (3), the etching method is reactive ion etching or chemical etching.

10. The method according to claim 9, wherein In step (3), the etching method is reactive ion etching.

11. The method according to claim 10, wherein Step (3) further includes a step of removing the photoresist from the etched sample.

12. The method according to claim 8, wherein Step (1) further includes the following steps: soaking the upper substrate and the lower substrate in a solvent, ultrasonically cleaning, and after the ultrasonic cleaning is completed, blowing the upper substrate and the lower substrate with nitrogen.

13. The method according to claim 12, wherein: The solvent is acetone or isopropyl alcohol; The power of the ultrasonic wave is 50-100 W; The time of the ultrasonic wave is 1-30 minutes; The thickness of the niobium metal thin film is 50-200 nm; and / or The method for growing the niobium metal thin film is magnetron sputtering or electron beam evaporation.

14. The method according to claim 13, wherein: The power of the ultrasonic wave is 90 W; The time of the ultrasonic wave is 10 minutes; The thickness of the niobium metal thin film is 80-150 nm; and / or The method for growing the niobium metal thin film is magnetron sputtering.

15. The method according to claim 8, characterized in that, Step (2) further includes the following steps: (A) Spin-coating a photoresist on the surface of the sample obtained in step (2) and baking it on a hot plate; (B) Laser direct writing on the sample with the spin-coated photoresist to expose the designed pattern; (C) Developing and fixing the sample after exposure, and after the fixing is completed, blowing the substrate with nitrogen.

16. The method according to claim 15, wherein: In step (A), the thickness of the photoresist is 1.0-4.8 microns; and / or In step (A), the photoresist is S1813 photoresist or SPR220 photoresist.

17. The method according to claim 16, wherein: In step (A), the thickness of the photoresist is 1.3 microns; and / or In step (A), the photoresist is S1813 photoresist.

18. The method according to claim 8, wherein Step (4) further includes the following steps: (a) Cleaning the sample obtained in step (3), and sequentially spin-coating MAA photoresist, PMMA photoresist and SX AR-PC conductive glue on it; (b) Electron beam exposing the Josephson junction pattern on the sample obtained in step (a); (c) Developing and fixing the sample after exposure, and after the fixing is completed, blowing the substrate with nitrogen; (d) Putting the sample obtained in step (c) into Plassys-MEB550s to prepare the Josephson junction; (e) Removing the photoresist and peeling the sample obtained in step (e) to obtain the niobium-based planar multi-superconducting qubit.

19. The method according to claim 18, characterized in that, In step (a): The thickness of the MAA photoresist is 80-400 nm; and / or The thickness of the PMMA photoresist is 100-400 nm.

20. The method according to claim 19, wherein In step (a): The thickness of the MAA photoresist is 150-250 nm; and / or The thickness of the PMMA photoresist is 200 nm.

21. The method according to claim 20, wherein In step (a), the thickness of the MAA photoresist is 200 nm.

22. The method according to claim 8, characterized in that Wherein, Step (5) further includes the following steps: (f) Spin-coating a photoresist on the surface of the sample obtained in step (4) and baking it on a hot plate; (g) Laser direct writing on the sample with the spin-coated photoresist to expose the designed pattern; (h) Develop and fix the sample after exposure. After fixing, blow nitrogen onto the substrate.

23. The method according to claim 22, wherein Among them, In the step (f): The thickness of the photoresist is 5 to 15 micrometers; and / or The photoresist is AZ P4620 photoresist or SPR220 photoresist.

24. The method according to claim 23, wherein Among them, In the step (f): The thickness of the photoresist is 5 to 10 micrometers; and / or The photoresist is AZ P4620 photoresist.

25. The method according to claim 24, wherein Among them, In the step (f), the thickness of the photoresist is 8 micrometers.

26. The method according to claim 8, wherein: In the step (6), the film thickness of the metal pillar is 5 to 10 um; and / or the method for growing the indium metal film is selected from one or more of the following: thermal evaporation, electron beam evaporation, magnetron sputtering; and / or In the step (7), the pressure welding pressure is 10-30 N / mm 2 ; and / or the pressure welding method is cold pressure welding or hot pressure welding.

27. The method according to claim 26, wherein: In the step (6), the film thickness of the metal pillar is 7 um, and / or the method for growing the indium metal film is thermal evaporation; and / or In the step (7), the pressure welding pressure is 15 N / mm 2 ; and / or the pressure welding method is cold pressure welding.

28. A quantum computing device based on a superconducting circuit, characterized in that, The quantum computing device includes the three-dimensional packaged superconducting qubit device according to any one of claims 1 to 7 or the three-dimensional packaged superconducting qubit device prepared by the method according to any one of claims 8 to 27.

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