Quantum computer, chip, device and manufacturing method thereof

Abstract

The invention discloses a quantum computer, a quantum chip, a quantum device and a manufacturing method thereof, and belongs to the field of quantum chip manufacturing. The method for synchronously manufacturing the plurality of quantum devices comprises the following steps of: providing a substrate of which the surface is provided with a pattern template layer; and coating the surface of the substrate through the deposition window in different directions by using an oblique evaporation process to form laminated film layers with thickness gradients in corresponding directions, and the two film layers are mutually complementary in thickness, so that a consistent distance is formed when vertically measured from each part of the top surface of the top layer to the surface of the substrate. Through the mode, the thickness consistency of the manufactured quantum device can be higher, so that the performance or parameters associated with the thickness consistency can be improved.

Description

Technical Field

[0001] The present application belongs to the field of quantum information, especially the field of quantum chip manufacturing. In particular, the present application relates to a quantum computer, chip, device and a manufacturing method thereof. Background Art

[0002] The Josephson junction is an important superconducting electronic component that plays a key role in quantum computing, quantum information processing, precision measurement, and basic research. This structure is known for its unique electrical properties and is a key component in the field of superconductors.

[0003] Therefore, when manufacturing superconducting quantum chips, ensuring the manufacturing quality of the Josephson junction has an important impact on the performance of the superconducting quantum chip. Summary of the invention

[0004] The examples of the present application provide a quantum computer, chip, device and manufacturing method thereof, which can be used to manufacture quantum devices such as Josephson junctions with higher thickness consistency, thereby improving the performance of quantum devices associated with thickness, such as the room temperature resistance of Josephson junctions.

[0005] The solution of this application example is implemented through the following contents.

[0006] In a first aspect, the present application example proposes a method for synchronously manufacturing multiple quantum devices, comprising:

[0007] Providing a substrate, forming a template layer with a pattern on the surface, the template layer comprising a plurality of regions having the same number as the quantum devices, and each region having a deposition window;

[0008] Using an oblique evaporation process, performing a first coating on the surface of the substrate through a deposition window in a first direction to form a first film layer having a thickness gradient along the first direction; and

[0009] Using an oblique evaporation process, a second film is deposited on the surface of the substrate through a deposition window in a second direction to form a second film layer having a thickness gradient along the second direction;

[0010] The second film layer covers the first film layer and has complementary thicknesses, so that a consistent distance is observed when measured vertically from the top surface of the second film layer to the substrate surface.

[0011] According to some examples of the present application, the first film layer and the second film layer are superconducting films of the same material;

[0012] Optionally, the material is aluminum or niobium.

[0013] According to some examples of the present application, the first film layer and the second film layer are made of different materials respectively.

[0014] According to some examples of the present application, the quantum device is a Josephson junction.

[0015] According to some examples of the present application, the Josephson junction is a cross-shaped junction.

[0016] According to some examples of the present application, the template layer is a photoresist layer or a hard mask.

[0017] According to some examples of the present application, during the manufacturing process, the switching from the first direction to the second direction is achieved by rotating the evaporation source and / or the substrate.

[0018] According to some examples of the present application, the first direction has a first included angle relative to the substrate surface, and the second direction has a second included angle relative to the substrate surface, and the first included angle is equal to the second included angle.

[0019] According to some examples of the present application, the first direction and the second direction are configured in a mirror-symmetric manner with respect to a given surface.

[0020] In a second aspect, some examples of the present application propose a quantum device, which is manufactured by implementing the method of synchronously manufacturing multiple quantum devices described above.

[0021] In a third aspect, some examples of the present application propose a quantum chip, which includes the aforementioned quantum device.

[0022] In a fourth aspect, some examples of the present application propose a quantum computer, which includes the aforementioned quantum chip.

[0023] In the above implementation process, when multiple quantum devices need to be manufactured simultaneously, through the method in the examples of the present application, the thicknesses of these quantum devices can be made more consistent or the same, and for a single quantum device, a consistent thickness can also be obtained due to this solution. That is, the above solution not only makes the thickness difference between different devices small, but also makes the thickness difference between different parts of a single device small. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] For a clearer illustration, the drawings required for use in the description will be briefly introduced below.

[0025] Figure 1 It is a schematic structural diagram of a substrate with a photoresist layer in two perspectives in the examples of the present application;

[0026] Figure 2 It is a schematic cross-sectional structural diagram of a quantum device with a two-layer structure in the examples of the present application;

[0027] Figure 3 Schematic diagram of the substrate with a photoresist layer for a cross-shaped Josephson junction in different oblique evaporation directions in the examples of this application;

[0028] Figure 4 Disclosed is a schematic process flow diagram of a method for synchronously manufacturing multiple quantum devices in the examples of this application. Detailed implementation manners

[0029] A Josephson Junction (JJ for short) is an important superconducting electronics component. It plays a crucial role in quantum computing, quantum information processing, precision measurement, and basic research. It forms a key component in the field of superconducting quantum computers due to its unique electrical properties.

[0030] The following elaborates on multiple aspects of the Josephson junction.

[0031] 1. Structure and principle:

[0032] A Josephson junction consists of a non-superconducting tunnel or insulating layer between two superconducting electrodes. In a superconductor, electrons form Cooper pairs and flow with zero resistance. When the non-superconductor in the Josephson junction is very thin, electrons can cross the tunnel by quantum tunneling. Such a quantum tunneling method leads to the Josephson effect.

[0033] 2. Josephson effect:

[0034] A Josephson junction can exhibit some amazing electrical properties. The most well-known ones are the DC Josephson effect and the AC Josephson effect.

[0035] DC Josephson Effect: At zero voltage, the current on both sides of the superconductor is quantized and can be described by the following relationship: where I is the current and I0 is the critical current, is the phase difference.

[0036] AC Josephson Effect: When the voltage on both sides of the superconductor is not zero, an alternating voltage is generated. This effect is widely used in frequency standards (such as atomic clocks) and voltage standards (such as superconducting voltage standards).

[0037] 3. Application fields:

[0038] Josephson junctions have important applications in quantum computing and quantum information processing and can be used as components for qubits. In addition, Josephson junctions can also be used in the field of precision measurement, such as voltage standards, frequency standards, and magnetic field measurement.

[0039] 4. Stability:

[0040] The stability of Josephson junctions is crucial for achieving high-performance qubits. To improve the stability of Josephson junctions, factors such as temperature, magnetic field, and current can be precisely controlled, and materials and fabrication processes can be optimized.

[0041] Some structural examples of Josephson junctions:

[0042] In superconducting qubits (Quantum Bit, qubit), Josephson junctions have various different structural types.

[0043] For example, Josephson junctions include cross junctions (Manhattan junctions), Dolan bridges, anisotropic junctions, etc. In addition, there are some other variants and derived structures of Josephson junctions to meet different quantum computing requirements.

[0044] The following is a brief description of these main structures, as well as some other possible structures of Josephson junctions.

[0045] Cross junction:

[0046] A cross junction is a special-shaped Josephson junction, usually formed by the intersection of two superconducting electrodes. Cross junctions can be used to implement charge qubits, phase qubits, and hybrid qubits.

[0047] Dolan bridge:

[0048] The Josephson junction structure in the form of a Dolan bridge includes a Josephson junction and an inductive element connected to it. Dolan bridges are usually used for the implementation of flux qubits.

[0049] Anisotropic junction:

[0050] An anisotropic junction is a Josephson junction with non-uniform superconducting properties. Its superconducting properties have different characteristics in different directions and are usually used to implement some special qubits.

[0051] Crossed Josephson Junction:

[0052] A crossed Josephson junction is a structure in which multiple Josephson junctions cross each other in a superconducting circuit and is used to implement complex qubit layouts.

[0053] As can be seen, with the continuous development of quantum technology, other new structural forms of Josephson junction structures and variants may emerge to meet the quantum computing and information processing needs in different fields. These different types of Josephson junction structures provide more flexibility and choices for the design and performance of qubits.

[0054] It should be noted that in the following text of this application, the optimization of the cross junction is mainly discussed and elaborated, but this does not limit that the solutions of the examples of this application can only be applied to the cross junction.

[0055] The manufacturing process of the existing Josephson junctions can be referred to as follows:

[0056] The process steps for preparing a cross-shaped Josephson junction can be briefly summarized as using a resist pattern mask and in-situ evaporation and oxidation to form a stacked Al / AlOx / Al JJ structure, and it can be mainly implemented through the following specific steps.

[0057] The following multiple operations are involved in the above process.

[0058] Patterning: Use a bilayer resist (PMMA + MMA; polymethyl methacrylate + methyl methacrylate) to form a cross pattern on the substrate through electron beam lithography (abbreviated as EBL).

[0059] Oblique evaporation: Evaporate a 36.6 nm thick aluminum (Al) layer for the first time (E-beam; electron beam evaporation); evaporate at an inclined angle of 45° to hide the line pattern perpendicular to the evaporation direction. Since the nominal film thickness is calibrated at an incident angle of 0°, the actual film thickness depends on the evaporation angle.

[0060] Oxidation: Introduce pure oxygen at 1.0 Torr for 10 min, and the surface of the first aluminum film is oxidized into an alumina surface (this oxidation is insufficient oxidation) to form the AlOx barrier / barrier layer of the JJ. The typical barrier layer thickness is 1.4 - 1.9 nm.

[0061] Oblique evaporation: Evaporate for the second time (E-beam) after the wafer is rotated 90°, and evaporate at an inclined angle of 45°. The thickness of the second aluminum is 96.7 nm.

[0062] Lift-off: Clean the substrate with an organic solution to obtain one or more required Josephson junctions.

[0063] In order to investigate various characteristics and performances of the Josephson junction, etc., the inventors have determined in practice that it can be evaluated through some characteristics described below.

[0064] I. Josephson junction stability

[0065] The inventors believe that to improve the uniform stability of Josephson junctions in quantum chips, the following key factors and methods need to be considered.

[0066] A. Material selection:

[0067] The performance of Josephson junctions highly depends on the superconducting materials used. Selecting high-quality and uniform superconducting materials is crucial. For example, both aluminum and silver are commonly used superconducting materials. Ensure that the material preparation process is strictly controlled to reduce non-uniformity.

[0068] B. Fabrication process:

[0069] When fabricating Josephson junctions, precise process control should be used to ensure the uniformity and stability of the structure. This includes depositing thin films of superconducting materials, defining the size and shape of the Josephson junctions, and controlling the interface quality of the materials.

[0070] C. Temperature control:

[0071] The operating temperature of superconducting materials usually needs to be maintained in the superconducting state, which is typically a very low temperature. The stability and uniformity of temperature are key factors in ensuring the stable performance of Josephson junctions. Use high-quality cooling systems and temperature control devices to reduce temperature gradients and fluctuations.

[0072] D. Stability of the current source:

[0073] Josephson junctions are usually manipulated by applying a current to them. Use a highly stable current source to ensure the uniformity and stability of the current, which is very important for obtaining consistent quantum operations.

[0074] E. Magnetic field shielding:

[0075] Magnetic fields have a great impact on the performance of Josephson junctions. In a laboratory environment, use magnetic field shielding devices to reduce the influence of external magnetic fields on the junctions.

[0076] F. Noise control:

[0077] Noise is a key issue in quantum computing. Reduce the influence of external electromagnetic noise and thermal noise on Josephson junctions through appropriate design and shielding.

[0078] G. Stability of the experimental setup:

[0079] Ensure the stability of the mechanical and electronic components of the experimental setup to reduce the influence of any vibrations or electronic noise on the Josephson junctions.

[0080] H. Monitoring and feedback:

[0081] Monitor the performance of the Josephson junction in real time and perform feedback control as needed to maintain its stability and uniformity.

[0082] In short, in order to improve the uniformity and stability of the Josephson junction, careful design and control can be considered in multiple aspects such as material selection, fabrication process, temperature control, current source, magnetic field shielding, noise control, and experimental setup. And this is crucial for achieving high-performance quantum computing and quantum information processing. The solution in the examples of this application mainly optimizes the stability of the Josephson junction from the perspective of the fabrication process.

[0083] II. Normal Temperature Resistance of Josephson Junction

[0084] Normal temperature resistance refers to the resistance characteristics exhibited by the Josephson junction at normal temperature (usually referring to room temperature, i.e., about 20 degrees Celsius or 293 Kelvin). At normal temperature, the Josephson junction is usually no longer in the superconducting state, so it will exhibit a finite resistance, and this resistance value is the normal temperature resistance of the Josephson junction.

[0085] The normal temperature resistance of the Josephson junction is usually expressed in ohms (Ω). It represents the voltage drop generated by the current passing through the junction at normal temperature. Normal temperature resistance is one of the electrical characteristics of the Josephson junction and is used to describe the resistance properties of the junction in the non-superconducting state. However, this value may vary depending on the specific type of Josephson junction, fabrication process, and material differences.

[0086] Normal temperature resistance usually corresponds to the key parameters of the Josephson junction at low temperature, mainly the critical current and critical voltage of the Josephson junction, as well as its energy gap, etc.

[0087] Critical Current:

[0088] The critical current is the maximum current that can pass through the Josephson junction in the superconducting state. At low temperature, when the Josephson junction is in the superconducting state, it can pass a non-zero current without inducing a voltage. The resistance at normal temperature corresponds to the situation of the critical current of the Josephson junction at low temperature. That is, when the current is greater than the critical current, the Josephson junction will deviate from the superconducting state and a voltage drop will occur.

[0089] Critical Voltage:

[0090] The critical voltage is the voltage that appears when the Josephson junction deviates from the superconducting state. When the current of the Josephson junction exceeds the critical current, it will cause the critical voltage, thereby bringing it into the normal state and the resistance becomes a finite value.

[0091] Energy Gap:

[0092] The energy gap of a superconductor refers to the minimum energy required for electrons to transition to an excited state in the superconducting state. The energy gap is usually related to the critical current and critical voltage because it is closely related to the stability of the superconducting state.

[0093] Josephson frequency:

[0094] An important property exhibited by a Josephson junction in the superconducting state is the Josephson frequency. The Josephson frequency is related to the energy gap of the Josephson junction and can be expressed by the following formula: F j = 2eV / h. Where F j is the Josephson frequency, e is the electron charge, V is the voltage of the Josephson junction, and h is the Planck constant. The Josephson frequency is related to the energy gap of the Josephson junction in the superconducting state.

[0095] Quantum bit frequency:

[0096] The frequency of a quantum bit refers to the energy difference between energy levels in its energy level structure, usually measured in Hertz (Hz). The frequency of a quantum bit can be affected by an external magnetic field, microwave excitation, and Josephson junctions. In some quantum bit systems, Josephson junctions are used as components of quantum bits.

[0097] It should be noted that the above parameters of Josephson junctions can typically achieve their typical superconducting electronics characteristics only at low temperatures. In the superconducting state, current can flow without resistance, and below the critical current, a Josephson junction exhibits zero resistance. At room temperature, due to thermal excitation and other factors, a Josephson junction will exhibit finite resistance.

[0098] Therefore, there is a close connection between the room temperature resistance and the critical current, critical voltage, and energy gap at low temperatures. These parameters all play important roles in the research and application of the superconducting properties of Josephson junctions.

[0099] The main purpose of the examples in this application is to provide a method for reducing the non-uniformity of the room temperature resistance of Josephson junctions generated in the manufacturing process. Moreover, through the solution of the examples in this application, the overall uniformity of the room temperature resistance of Josephson junctions can be made within 5%, thereby improving the quality of Josephson junctions.

[0100] As described above, the oblique evaporation process and in-situ oxidation process (incomplete oxidation) are mainly used in the preparation process of Josephson junctions. And the inventors of this application found in practice that under the same coating parameters and lithography parameters, the junction resistance of Josephson junctions is mainly affected by the junction line width (lithography accuracy and development accuracy) and the thickness of the oxide layer (oxidation gas pressure and time).

[0101] For example, there is a difference in the thickness of the entire film caused by inclined evaporation. This difference is mainly caused by the systematic error of inclined evaporation. Its specific manifestation is that the thickness near the evaporation source is higher than that far from the evaporation source. This phenomenon can be simulated to measure the specific difference. In a 4-inch wafer, a single 45° inclined evaporation is performed, and the thickness difference between the top and bottom in the inclined evaporation direction is 10 nm. Moreover, this difference is much higher than about 2 nm in the non-inclined evaporation direction (transverse). Here, the film thickness in the middle region is also measured to be approximately H×cosθ (H is the designed thickness, and θ is the tilt angle). The larger the tilt angle, the greater the film thickness deviation; the farther away from the evaporation source, the smaller the thickness.

[0102] To address such a problem, a solution is proposed in the examples of the present application to overcome the above problems. Specifically, a method for synchronously manufacturing multiple quantum devices is disclosed in the examples. And this method for synchronously manufacturing multiple quantum devices can also be used in the applications of manufacturing various other devices and apparatuses with multilayer structures.

[0103] It should be emphasized that although synchronously manufacturing multiple quantum devices is mentioned in the solution, this does not mean that the solution of the examples of the present application can only be used for simultaneously manufacturing multiple quantum devices, nor does it mean that the solution of the examples of the present application can only be used for manufacturing multiple quantum devices. On the contrary, the solution of the examples of the present application can also be used for distributively manufacturing multiple quantum devices. This solution can also be used for manufacturing a single quantum device.

[0104] This solution provides a method for compensating film coating. Specifically, there is normal coating on a large-sized substrate, which is improved by the rotation of the plating pot or the self-rotation of the substrate. However, for preparing Josephson junctions by the inclined evaporation process, the inclined evaporation angle and the mask model are obtained through simulation calculations. Evaporation is performed in one direction for the first time, otherwise the other direction will be blocked to obtain the required device.

[0105] In contrast, referring to Figure 4 , this method for synchronously manufacturing multiple quantum devices includes:

[0106] Step 1: Provide a substrate as shown in Figure 1 . The substrate 201 has a template layer 202 with patterns formed on its surface. The template layer 202 includes multiple regions with the same number as the quantum devices, and each region has a deposition window 203. The template layer therein can be a photoresist layer or a hard mask (such as SOI).

[0107] Step 2: Use the inclined evaporation process to perform the first coating on the surface of the substrate through the deposition window in the first direction to form a first film layer 101 with a thickness gradient along the first direction (in the Figure 2 orientation, the thickness gradually decreases from right to left); and

[0108] Step 3: Using the inclined evaporation process, perform a second coating on the substrate surface through the deposition window in the second direction to form a second film layer 102 having a thickness gradient along the second direction (in the Figure 2 orientation shown, the thickness gradually increases from right to left). Among them, the switching from the first direction to the second direction can be achieved by rotating the evaporation source or the substrate, or synchronously rotating the evaporation source and the substrate.

[0109] In the process of implementing the above solution, the second film layer covers the first film layer, and the first film layer and the second film layer are complementary in thickness to each other, so that when measured vertically from each point on the top surface of the second film layer to the substrate surface, there is a consistent distance.

[0110] In order to make the thickness of the first film layer and the second film layer better complementary and make the thickness uniformity of the manufactured quantum devices higher, the first direction and the second direction can be purposefully configured. For example, define a first angle of the first direction relative to the substrate surface, and a second angle of the second direction relative to the substrate surface, and make the first angle equal to the second angle when specifically implementing the manufacturing process. Further, it can be selected that the first direction and the second direction are configured in a mirror-symmetrical manner with respect to a given surface.

[0111] In this way, when synchronously manufacturing multiple quantum devices, these quantum devices can have more consistent or the same thickness. For example, taking the Figure 1 double-layer structure as an example, the quantum device therein can be regarded as a thin film (which can be used to manufacture transmission lines, coplanar waveguides, capacitors, Josephson junctions, etc.), and it has a double-layer structure. In the form of a quantum device in the context of a Josephson junction (such as a cross junction), the quantum device can be used as a layer of superconductor in the Josephson junction.

[0112] In the above process, the first film layer and the second film layer can be made of the same material, so as not to be the same material superconducting thin film. The material therein is, for example, aluminum or niobium. Or, if necessary, the first film layer and the second film layer can also be made of different materials.

[0113] For a Josephson junction, since it has two superconducting layers, in some examples, the above-mentioned solution can be selected to manufacture these two superconducting layers. That is, both the upper and lower layer metals (such as superconducting aluminum) of the Josephson junction are subjected to two inclined evaporations, each plating once at ±45°.

[0114] Refer to Figure 3 for the specific rotation and tilt conditions:

[0115] JJ1 (the first superconductor in the Josephson junction that contacts the substrate) and JJ2 (the second superconductor in the Josephson junction that contacts the substrate) each undergo two inclined evaporations during the manufacturing process.

[0116] The first evaporation of JJ1 is at an angle of +45° relative to the substrate surface, and 18.3 nm is evaporated to form; then, relative to the substrate surface at -45° (the substrate rotates 180° around the vertical line of its surface based on the previous time), 18.3 nm is evaporated for the second time.

[0117] JJ2 is at an angle of +45° relative to the substrate surface, and 18.3 nm is formed by the first evaporation; then, relative to the substrate surface at -45° (the substrate rotates 180° around the vertical line of its surface based on the previous time), 18.3 nm is formed by the second evaporation.

[0118] In the above way, the thickness difference of the manufactured thin film caused by the difference in distance from the evaporation source can be eliminated. It should be noted that since the line width in the process of manufacturing Josephson junctions is usually at the nanometer level, such as about 200 nm. Ensure that the position where the chip is placed is as horizontal as possible, otherwise two superimposed lines will appear in the ±45° coating. Therefore, when manufacturing the cross junction, the overlapping area of JJ1 and JJ2 may increase, but it has a positive effect on the thickness stability.

[0119] In summary, through the above scheme, when multiple quantum devices are synchronously manufactured, these quantum devices can have more consistent thicknesses, so that the performance of these quantum devices is also more consistent. In this way, when multiple qubits with the same design are manufactured in a multi-bit superconducting quantum chip, through such a scheme, the performance of these qubits can be made closer and more consistent. And it can also be known that for a single quantum device, the uniformity of its film thickness is also improved.

[0120] More specifically, the thickness non-uniformity between the above-mentioned multiple quantum devices and within a single quantum device itself caused by inclined evaporation can be alleviated and improved by the method of evaporating in the above two directions respectively.

[0121] Furthermore, by applying the quantum devices manufactured through the foregoing scheme or its manufacturing process to the manufacturing process of quantum chips and quantum computers, it can also be known that corresponding effects can be brought to these quantum devices.

[0122] The structure, features, and function effects of this application have been described in detail based on the embodiments shown in the drawings above. The above are only the preferred embodiments of this application, but this application is not limited to the implementation scope shown in the drawings. Any changes made according to the concept of this application, or modified into equivalent embodiments with equivalent changes, still within the spirit covered by the specification and drawings, should be within the protection scope of this application.

Claims

1. A method for synchronously manufacturing multiple quantum devices, characterized in that, include: Providing a substrate, forming a template layer with a pattern on the surface, wherein the template layer includes a plurality of regions having the same number as the quantum devices, and each region has a deposition window; Using an oblique evaporation process, a first film is deposited on the surface of the substrate through a deposition window in a first direction to form a first film layer having a thickness gradient along the first direction; as well as Using an oblique evaporation process, a second film is deposited on the surface of the substrate through a deposition window in a second direction to form a second film layer having a thickness gradient along the second direction; The second film layer covers the first film layer and has complementary thicknesses, so that a consistent distance is observed when measured vertically from the top surface of the second film layer to the substrate surface.

2. The method for synchronously manufacturing a plurality of quantum devices according to claim 1, wherein, The first film layer and the second film layer are superconducting films of the same material, and optionally, the material is aluminum or niobium; And / or, the first film layer and the second film layer are made of different materials respectively; And / or, the template layer is a photoresist layer or a hard mask.

3. The method for synchronously manufacturing multiple quantum devices according to claim 1, wherein The quantum device is a Josephson junction.

4. The method for synchronously manufacturing multiple quantum devices according to claim 3, wherein, The Josephson junction is a cross junction.

5. The method for synchronously manufacturing multiple quantum devices according to claim 1, wherein During the manufacturing process, the switching from the first direction to the second direction is achieved by means of rotating the evaporation source and / or the substrate.

6. The method for synchronously manufacturing multiple quantum devices according to claim 5, characterized in that, The first direction has a first angle relative to the substrate surface, the second direction has a second angle relative to the substrate surface, and the first angle is equal to the second angle.

7. The method for synchronously manufacturing multiple quantum devices according to claim 6, wherein The first direction and the second direction are arranged in a mirror-symmetric manner on a given surface.

8. A quantum device, characterized in that, The method is obtained by implementing the method for simultaneously manufacturing a plurality of quantum devices as claimed in any one of claims 1 to 7.

9. A quantum chip, characterized in that, Comprising the quantum device according to claim 8.

10. A quantum computer, characterized in that, Comprising the quantum chip according to claim 9.

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