Quantum device, method for manufacturing quantum device, and method for inspecting quantum device

Abstract

This quantum device comprises: a first Josephson junction element which is formed on a substrate; and a second Josephson junction element and a first temperature detection structure, which are formed in a first region of the substrate. The first Josephson junction element includes: a first superconducting film and a second superconducting film; and a first oxide film that is provided between the first superconducting film and the second superconducting film. The second Josephson junction element includes: a third superconducting film and a fourth superconducting film; and a second oxide film that is provided between the third superconducting film and the fourth superconducting film. The first temperature detection structure irreversibly deforms at a first temperature that is lower than the temperature at which the superconducting characteristics of the third superconducting film or the fourth superconducting film change. The quantum device can be used in, for example, quantum computing.

Description

Quantum device, quantum device manufacturing method, and quantum device inspection method

[0001] The present disclosure relates to quantum devices, methods for manufacturing quantum devices, and methods for inspecting quantum devices.

[0002] Quantum computers sometimes use quantum devices with quantum bits that include Josephson junction elements. Qubits that include Josephson junction elements are sometimes called transmons. Qubits that include Josephson junction elements have a resonant frequency that varies depending on the resistance of the Josephson junction element. Furthermore, the resistance of a Josephson junction element is largely determined by the resistance of the oxide film contained in the Josephson junction element. Therefore, techniques for precisely adjusting the resistance of the oxide film, for example, the resistance of the oxide film at room temperature, to a predetermined value have been studied. For example, one proposed method for adjusting the resistance of the oxide film is to form a Josephson junction element whose resistance value is lower than a predetermined value and then increase the oxidation level of the oxide film by irradiating it with laser light.

[0003] US Patent Application No. 2022 / 0140221 US Patent Application No. 2019 / 0165246 JP 2003-031862 A JP 2015-192071 A

[0004] Even if the resistance value of the oxide film is adjusted to a predetermined value by irradiation with laser light, the Josephson junction element may be exposed to an excessively high temperature by the laser light irradiation, and the superconducting characteristics of the Josephson junction element may change. If the superconducting characteristics of the Josephson junction element change, the characteristics of the quantum bit may also change. Therefore, it is desirable to determine the temperature to which the Josephson junction element is exposed by irradiation with laser light. However, it has been difficult to determine the temperature to which the Josephson junction element is exposed by irradiation with laser light.

[0005] An object of the present disclosure is to provide a quantum device, a quantum device manufacturing method, and a quantum device inspection method that can identify the temperature to which a Josephson junction element has been exposed by irradiation with laser light.

[0006] According to one aspect of the present disclosure, there is provided a quantum device comprising: a first Josephson junction element formed on a substrate; a second Josephson junction element and a first temperature sensing structure formed in a first region of the substrate; the first Josephson junction element having first and second superconducting films and a first oxide film provided between the first and second superconducting films; the second Josephson junction element having third and fourth superconducting films and a second oxide film provided between the third and fourth superconducting films; and the first temperature sensing structure irreversibly deforming at a first temperature lower than a temperature at which a superconducting characteristic of the third or fourth superconducting film changes.

[0007] According to the present disclosure, it is possible to identify the temperature to which a Josephson junction device is exposed by irradiation with laser light.

[0008] FIG. 1 is a diagram illustrating a layout of a quantum device according to the first embodiment. FIG. 2 is a circuit diagram illustrating a circuit included in a functional region. FIG. 3 is a plan view illustrating the configuration of the functional region. FIG. 4 is a plan view illustrating the configuration of the test region. FIG. 5 is a cross-sectional view illustrating the configurations of the functional region and the test region. FIG. 6 is a flowchart illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 7 is a plan view (part 1) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 8 is a plan view (part 2) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 9 is a plan view (part 3) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 10 is a plan view (part 4) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 11 is a plan view (part 5) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 12 is a plan view (part 6) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 13 is a plan view (part 7) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 14 is a plan view (part 8) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 15 is a cross-sectional view (part 1) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 16 is a cross-sectional view (part 2) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 17 is a cross-sectional view (part 3) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 18 is a cross-sectional view (part 4) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 19 is a cross-sectional view (part 5) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 20 is a cross-sectional view (part 6) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 21 is a cross-sectional view (part 7) illustrating a method for manufacturing a quantum device according to the first embodiment. FIG. 22 is a plan view illustrating a temperature detection structure included in a quantum device according to the second embodiment. FIG. 23 is a plan view (part 1) illustrating a method for forming a metal film according to the second embodiment. FIG. 24 is a plan view (part 2) illustrating a method for forming a metal film according to the second embodiment. FIG. 25 is a plan view (part 3) illustrating a method for forming a metal film according to the second embodiment. FIG. 26 is a plan view illustrating a temperature detection structure included in a quantum device according to a third embodiment. FIG. 27 is a plan view (part 1) showing a method for forming a metal film in the third embodiment.FIG. 28 is a plan view (part 2) showing a method for forming a metal film in the third embodiment. FIG. 29 is a plan view showing a temperature detection structure included in a quantum device according to the fourth embodiment. FIG. 30 is a plan view (part 1) showing a method for forming a metal film in the fourth embodiment. FIG. 31 is a plan view (part 2) showing a method for forming a metal film in the fourth embodiment. FIG. 32 is a plan view (part 3) showing a method for forming a metal film in the fourth embodiment. FIG. 33 is a plan view (part 4) showing a method for forming a metal film in the fourth embodiment. FIG. 34 is a plan view (part 5) showing a method for forming a metal film in the fourth embodiment. FIG. 35 is a plan view showing a temperature detection structure included in a quantum device according to the fourth embodiment. FIG. 36 is a cross-sectional view showing a temperature detection structure included in a quantum device according to the fourth embodiment. FIG. 37 is a diagram (part 1) showing a method for forming a metal film in the fifth embodiment. FIG. 38 is a diagram (part 2) showing a method for forming a metal film in the fifth embodiment. Fig. 39 is a diagram (part 3) showing a method for forming a metal film in the fifth embodiment. Fig. 40 is a diagram showing a layout of a quantum device according to the sixth embodiment. Fig. 41 is a diagram showing a layout of a quantum device according to the seventh embodiment. Fig. 42 is a diagram showing a layout of a quantum device according to the eighth embodiment.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Note that in this specification and drawings, components having substantially the same functional configurations may be denoted by the same reference numerals to avoid redundant description. In this disclosure, the X1-X2 direction, the Y1-Y2 direction, and the Z1-Z2 direction are defined as mutually orthogonal directions. A plane including the X1-X2 direction and the Y1-Y2 direction will be referred to as the XY plane, a plane including the Y1-Y2 direction and the Z1-Z2 direction will be referred to as the YZ plane, and a plane including the Z1-Z2 direction and the X1-X2 direction will be referred to as the ZX plane. For convenience, the Z1-Z2 direction will be defined as the up-down direction, with the Z1 side referred to as the upper side and the Z2 side referred to as the lower side. Furthermore, a planar view refers to viewing an object from the Z1 side, and a planar shape refers to the shape of an object viewed from the Z1 side.

[0010] First Embodiment A first embodiment will be described. The first embodiment relates to a quantum device. Fig. 1 is a diagram showing the layout of a quantum device according to the first embodiment.

[0011] As shown in FIG. 1 , the quantum device 1 according to the first embodiment has a central region 41 and a peripheral region 42. In a plan view, the central region 41 is surrounded by the peripheral region 42. The central region 41 has, for example, four functional regions 51. For example, the planar shape of the functional regions 51 is square, and two functional regions 51 are arranged side by side in the X1-X2 direction and the Y1-Y2 direction. Furthermore, the peripheral region 42 has, for example, the same number of test regions 52 as the functional regions 51. For example, the test regions 52 are arranged at the four corners of the peripheral region 42.

[0012] Here, the functional area 51 and the test area 52 will be described. Fig. 2 is a circuit diagram showing the circuit included in the functional area 51. Fig. 3 is a plan view showing the configuration of the functional area 51. Fig. 4 is a plan view showing the configuration of the test area 52. Fig. 5 is a cross-sectional view showing the configuration of the functional area 51 and the test area 52.

[0013] 2, the functional region 51 has a Josephson junction element 10 and a capacitor 60. The Josephson junction element 10 and the capacitor 60 are connected in parallel to each other, and the Josephson junction element 10 and the capacitor 60 constitute a transmon 70. The transmon 70 is an example of a circuit.

[0014] As shown in Figures 3 to 5, the quantum device 1 has a substrate 50. The substrate 50 is, for example, a silicon substrate. Figure 5 illustrates a cross section taken along line II in Figure 3, a cross section taken along line II-II in Figure 4, and a cross section taken along line III-III in Figure 4 side by side. Figure 5(a) shows a cross section taken along line II in Figure 3, Figure 5(b) shows a cross section taken along line II-II in Figure 4, and Figure 5(c) shows a cross section taken along line III-III in Figure 4.

[0015] As shown in FIGS. 3 and 5 , the functional region 51 has a lower superconducting film 11, an upper superconducting film 12, and an oxide film 13. The lower superconducting film 11 and the upper superconducting film 12 are provided on a substrate 50. The lower superconducting film 11 has a portion extending parallel to the X1-X2 direction. The lower superconducting film 11 is, for example, an aluminum film. The oxide film 13 is provided on the upper surface of the lower superconducting film 11 and covers the upper surface of the lower superconducting film 11. The oxide film 13 is, for example, an aluminum oxide film. The upper superconducting film 12 extends parallel to the Y1-Y2 direction and has a portion that intersects with the portion of the lower superconducting film 11 that extends parallel to the X1-X2 direction in a planar view. The upper superconducting film 12 is, for example, an aluminum film or a niobium film. At the portion where the lower superconducting film 11 and the upper superconducting film 12 intersect with each other in a planar view, the upper superconducting film 12 is provided on the oxide film 13. The oxide film 13 is provided between the lower superconducting film 11 and the upper superconducting film 12. The lower superconducting film 11 contacts the lower surface of the oxide film 13, and the lower surface of the upper superconducting film 12 contacts the upper surface of the oxide film 13. The overlapping portion of the lower superconducting film 11, the oxide film 13, and the upper superconducting film 12 functions as a Josephson junction device 10. The Josephson junction device 10 is an example of a first Josephson junction device. The lower superconducting film 11 is an example of a first superconducting film, the upper superconducting film 12 is an example of a second superconducting film, and the oxide film 13 is an example of a first oxide film.

[0016] As shown in FIGS. 4 and 5 , the test area 52 has a lower superconducting film 21, an upper superconducting film 22, and an oxide film 23. The lower superconducting film 21 and the upper superconducting film 22 are provided on a substrate 50. The lower superconducting film 21 has a portion extending parallel to the X1-X2 direction. The lower superconducting film 21 is, for example, an aluminum film. The oxide film 23 is provided on the upper surface of the lower superconducting film 21 and covers the upper surface of the lower superconducting film 21. The oxide film 23 is, for example, an aluminum oxide film. The upper superconducting film 22 extends parallel to the Y1-Y2 direction and has a portion that intersects with the portion of the lower superconducting film 21 that extends parallel to the X1-X2 direction in a planar view. The upper superconducting film 22 is, for example, an aluminum film or a niobium film. At the portion where the lower superconducting film 21 and the upper superconducting film 22 intersect with each other in a planar view, the upper superconducting film 22 is provided on the oxide film 23. The oxide film 23 is provided between the lower superconducting film 21 and the upper superconducting film 22. The lower superconducting film 21 contacts the lower surface of the oxide film 23, and the lower surface of the upper superconducting film 22 contacts the upper surface of the oxide film 23. The overlapping portion of the lower superconducting film 21, the oxide film 23, and the upper superconducting film 22 functions as a Josephson junction device 20. The Josephson junction device 20 is an example of a second Josephson junction device. The lower superconducting film 21 is an example of a third superconducting film, the upper superconducting film 22 is an example of a fourth superconducting film, and the oxide film 23 is an example of a second oxide film. The test area 52 is an example of a first area.

[0017] The thickness of the oxide film 13 is substantially equal to the thickness of the oxide film 23. For example, the thickness of the oxide film 23 is 99% or more and 101% or less of the thickness of the oxide film 13.

[0018] As shown in FIGS. 3 and 4 , the test region 52 includes a temperature detection region 30. The temperature detection region 30 is disposed closer to the Josephson junction element 20 than the Josephson junction element 10. A metal film 101 is provided in the temperature detection region 30. The metal film 101 is provided near the Josephson junction element 20 in a plan view. The metal film 101 has, for example, a thin line shape extending parallel to the X1-X2 direction. The dimension (thickness) of the metal film 101 in the Z1-Z2 direction is, for example, 0.1 μm or more and 1.0 μm or less. The dimension (width) of the narrowest portion of the metal film 101 in the Y1-Y2 direction is, for example, 1 μm or more and 10 μm or less. As will be described later, the Josephson junction element 20 is irradiated with laser light. A first distance between the metal film 101 and the Josephson junction element 20 is equal to or less than the radius of the spot of the laser light irradiated on the Josephson junction element 20, for example, 100 μm or less. The first distance is preferably 80 μm or less, more preferably 60 μm or less. Here, the first distance between the metal film 101 and the Josephson junction element 20 is the distance between the farthest point of the metal film 101 from the Josephson junction element 20 and the farthest point of the Josephson junction element 20 from the metal film 101.

[0019] The metal film 101 irreversibly deforms, for example, at a first temperature lower than the temperature (e.g., 200°C) at which the superconducting characteristics of the lower superconducting film 21 or the upper superconducting film 22 change. For example, the temperature at which the superconducting characteristics of the lower superconducting film 21 change is the temperature at which the lower superconducting film 21 recrystallizes, and the temperature at which the superconducting characteristics of the upper superconducting film 22 change is the temperature at which the upper superconducting film 22 recrystallizes. The material of the metal film 101 is, for example, a tin (Sn)-lead (Pb) alloy or a bismuth (Bi)-tin (Sn) alloy, and the melting point of the metal film 101 is, for example, 190°C. During laser light irradiation, the temperature of the metal film 101 becomes approximately the same as the temperature of the portion (provisional JJ element) that will become the Josephson junction element 20. Therefore, if the temperature of the provisional JJ element becomes higher than the melting point of the metal film 101 during laser light irradiation, the metal film 101 melts and irreversibly deforms. This changes the resistance value of the metal film 101. For example, the resistance value between both ends of the metal film 101 in the X1-X2 direction changes. Depending on the degree of deformation, a break may occur between both ends of the metal film 101 in the X1-X2 direction. The melting point of the metal film 101 is lower than the temperature at which the superconducting properties of the lower superconducting film 21 or the upper superconducting film 22 change, and is, for example, 140°C or higher and 190°C or lower. The melting point of the metal film 101 may be 140°C or higher and 180°C or lower. The metal film 101 is an example of a first temperature detection structure.

[0020] Next, a method for manufacturing the quantum device 1 according to the first embodiment will be described. FIG. 6 is a flowchart illustrating the method for manufacturing the quantum device 1 according to the first embodiment. FIGS. 7 to 14 are plan views illustrating the method for manufacturing the quantum device 1 according to the first embodiment. FIGS. 15 to 21 are cross-sectional views illustrating the method for manufacturing the quantum device 1 according to the first embodiment. FIGS. 15 to 21 show cross-sectional changes along line II in FIG. 3, along line II-II in FIG. 4, and along line III-III in FIG. 4. FIGS. 15(a) to 21(a) show cross-sectional changes along line II in FIG. 3, FIGS. 15(b) to 21(b) show cross-sectional changes along line II-II in FIG. 4, and FIGS. 15(c) to 21(c) show cross-sectional changes along line III-III in FIG. 4.

[0021] First, a provisional Josephson junction element (JJ element) 10X that will become the Josephson junction element 10, a provisional JJ element 20X that will become the Josephson junction element 20, and a metal film 101 are formed (step S1). The metal film 101 may be formed after the provisional JJ elements 10X and 20X are formed, or the provisional JJ elements 10X and 20X may be formed after the metal film 101 is formed. Here, a method of forming the metal film 101 after forming the provisional JJ elements 10X and 20X will be described.

[0022] 7 and 15, a mask 110 having openings 111 and 112 is formed on a substrate 50. The opening 111 exposes a region of the substrate 50 where the lower superconducting film 11 and the upper superconducting film 12 are to be formed. The opening 112 exposes a region of the substrate 50 where the lower superconducting film 21 and the upper superconducting film 22 are to be formed. In forming the mask 110, a photoresist is applied onto the substrate 50, and then the photoresist is exposed and developed.

[0023] 8 and 16, oblique deposition 116 of aluminum is then performed in a direction tilted from the Z1 side to the X2 side when viewed from the top surface of the substrate 50. As a result, the lower superconducting film 11 is formed on the substrate 50 in the opening 111, and the lower superconducting film 21 is formed on the substrate 50 in the opening 112. Oblique deposition 116 may also be performed in a direction tilted from the Z1 side to the X1 side when viewed from the top surface of the substrate 50.

[0024] Thereafter, the upper surfaces of the lower superconducting film 11 and the lower superconducting film 21 are oxidized. In oxidizing the upper surfaces of the lower superconducting film 11 and the lower superconducting film 21, for example, the atmosphere in the film formation chamber in which the lower superconducting film 11 and the lower superconducting film 21 are formed is changed to an oxygen atmosphere, and the upper surfaces of the lower superconducting film 11 and the lower superconducting film 21 are exposed to the oxygen atmosphere for several minutes to several tens of minutes. As a result, as shown in FIGS. 9 and 17 , an oxide film 13X is formed on the upper surface of the lower superconducting film 11, and an oxide film 23X is formed on the upper surface of the lower superconducting film 21.

[0025] Next, as shown in FIGS. 10 and 18 , oblique deposition 117 of aluminum or niobium is performed from a direction tilted from the Z1 side to the Y1 side when viewed from the top surface of the substrate 50. As a result, an upper superconducting film 12 is formed on the substrate 50 and the oxide film 13X within the opening 111, and an upper superconducting film 22 is formed on the substrate 50 and the oxide film 24X within the opening 112. Oblique deposition 117 may also be performed from a direction tilted from the Z1 side to the Y2 side when viewed from the top surface of the substrate 50. The upper superconducting films 12 and 22 can be formed, for example, in the same film formation chamber in which the oxide films 13X and 23X are formed. Following the formation of the upper superconducting films 12 and 22, a provisional JJ element 10X including the lower superconducting film 11, the oxide film 13X, and the upper superconducting film 12 and a provisional JJ element 20X including the lower superconducting film 21, the oxide film 23X, and the upper superconducting film 22 are obtained. The provisional JJ element 10X is an example of a first provisional Josephson junction element, and the provisional JJ element 20X is an example of a second provisional Josephson junction element.

[0026] 11 and 19, the mask 110 is removed. The mask 110 can be removed by, for example, immersion in a stripping liquid or a solvent. When the lower superconducting films 11 and 21 and the upper superconducting films 12 and 22 are formed, evaporated materials such as aluminum adhere to the mask 110, but the adhered materials are removed when the mask 110 is removed.

[0027] 11 and 19, a mask 120 having openings 121 is formed on the substrate 50, the lower superconducting film 11, the oxide film 13X, the upper superconducting film 12, the lower superconducting film 21, the oxide film 23X, and the upper superconducting film 22. The openings 121 expose the regions of the substrate 50 where the metal film 101 is to be formed. In forming the mask 120, a photoresist is applied onto the substrate 50, and then the photoresist is exposed and developed.

[0028] 12 and 20, vapor deposition 126 of an Sn—Pb alloy or a Bi—Sn alloy is performed from the Z1 side as viewed from the top surface of the substrate 50. As a result, a metal film 101 is formed on the substrate 50 within the opening 121.

[0029] 13 and 21, the mask 120 is removed. The mask 120 can be removed by, for example, immersion in a stripping solution or a solvent. When the metal film 101 is formed, a vapor-deposited material such as a Sn—Pb alloy or a Bi—Sn alloy adheres to the mask 120, but the adhered material is removed when the mask 120 is removed.

[0030] In this manner, the provisional JJ element 10X that will become the Josephson junction element 10, the provisional JJ element 20X that will become the Josephson junction element 20, and the metal film 101 can be formed.

[0031] Thereafter, the resistance value of the provisional JJ element 20X is measured and recorded (step S2). In measuring the resistance value of the provisional JJ element 20X, for example, the resistance value between the lower superconducting film 21 and the upper superconducting film 22 is measured.

[0032] Next, the resistance value of the metal film 101 is measured and recorded (step S3). In measuring the resistance value of the metal film 101, the resistance value between both ends of the metal film 101 in the X1-X2 direction is measured.

[0033] Next, laser light is irradiated (step S4). Here, the provisional JJ element 10X is irradiated with laser light, and as shown in FIG. 14, the provisional JJ element 20X and the metal film 101 are irradiated with laser light 25. This laser light irradiation is performed with a power and time based on the resistance value acquired in step S1. By preparing in advance a table showing the relationship between the resistance value and the power and time of laser light irradiation, the power and time can be determined based on the resistance value acquired in step S1.

[0034] Thereafter, the provisional JJ elements 10X, 20X, and metal film 101 are cooled (step S5) by, for example, air-cooling the provisional JJ elements 10X, 20X, and metal film 101 to room temperature.

[0035] Subsequently, the resistance value of the temporary JJ element 20X is measured and recorded (step S6).

[0036] Next, it is determined whether the resistance value acquired in step S6 has reached a predetermined value (step S7). If the resistance value has not reached the predetermined value, the process returns to step S4, and steps S4 to S7 are repeated until the resistance value of the temporary JJ element 20X reaches the predetermined value.

[0037] Then, when the resistance value of the temporary JJ element 20X reaches a predetermined value, the resistance value of the metal film 101 is measured and recorded (step S8).

[0038] Thereafter, the resistance value acquired in step S3 is compared with the resistance value acquired in step S8, and the temperature reached by the metal film 101 during irradiation with the laser light is determined based on the result (step S9). For example, if the difference between the resistance value acquired in step S3 and the resistance value acquired in step S8 is equal to or greater than a predetermined threshold, it is determined that the metal film 101 is exposed to a temperature higher than its melting point. Finally, the resistance value of the provisional JJ element 10X may be measured.

[0039] Furthermore, the oxide films 13X and 23X are irradiated with laser light one or more times to obtain the oxide films 13 and 23 adjusted to desired resistance values. In this manner, the quantum device 1 according to the first embodiment including the Josephson junction elements 10 and 20 can be manufactured.

[0040] In this embodiment, the resistance value of the provisional JJ element 20X is measured each time the laser beam is irradiated. Therefore, the resistance value of the provisional JJ element 10X can be appropriately adjusted, and the Josephson junction elements 10 and 20 having the desired resistance value can be obtained. Furthermore, since the temperature reached by the metal film 101 is determined after the resistance value of the provisional JJ element 20X reaches a predetermined value, the temperature reached by the provisional JJ element 20X when irradiated with the laser beam 25 can be estimated. Furthermore, since the laser beam is irradiated onto the provisional JJ element 10X under the same conditions as those for irradiating the provisional JJ element 20X with the laser beam, it is also possible to identify the temperature to which the Josephson junction element 10 was exposed.

[0041] If the deformation of the metal film 101 is significant, it may be determined that the metal film 101 has been exposed to a temperature higher than the melting point by visual observation or observation with an optical microscope, instead of measuring the resistance value.

[0042] When forming multiple quantum devices on a single substrate (wafer) and then dividing the substrate, it is possible to prepare a reference quantum device without providing the test region 52 and use the reference quantum device to determine the laser light irradiation conditions. However, before the laser light irradiation, there is a large manufacturing variation in the oxide film among the multiple Josephson junction elements within a single substrate. Therefore, when laser light is irradiated using the conditions determined from the reference quantum device, even if the desired resistance value is obtained for the Josephson junction elements in one quantum device, the desired resistance value may not be obtained for the Josephson junction elements in another quantum device.

[0043] In this embodiment, even when multiple quantum devices are formed on a single substrate and the substrate is separated into individual pieces, laser light can be irradiated under appropriate conditions for each quantum device, thereby enabling the Josephson junction elements in each quantum device to have a desired resistance value.

[0044] Second Embodiment Next, a second embodiment will be described. The second embodiment differs from the first embodiment mainly in the configuration of the temperature detection structure. Fig. 22 is a plan view showing the temperature detection structure included in the quantum device according to the second embodiment.

[0045] In the quantum device according to the second embodiment, as shown in FIG. 22 , the test region 52 has metal films 201, 202, and 203 instead of the metal film 101. The metal films 201, 202, and 203 are provided near the Josephson junction device 20 in a plan view. The metal films 201, 202, and 203 have, for example, a thin wire shape extending parallel to the X1-X2 direction. The dimension (thickness) of the metal films 201, 202, and 203 in the Z1-Z2 direction is, for example, 0.1 μm or more and 1.0 μm or less. The dimension (width) of the narrowest portion of the metal films 201, 202, and 203 in the Y1-Y2 direction is, for example, 1 μm or more and 10 μm or less. A first distance between each of the metal films 201, 202, and 203 and the Josephson junction device 20 is equal to or less than the radius of the spot of the laser light irradiated on the Josephson junction device 20, for example, 100 μm or less. The first distance is preferably 80 μm or less, more preferably 60 μm or less. Here, the first distance between each of the metal films 201, 202, and 203 and the Josephson junction device 20 is the distance between the farthest point of each of the metal films 201, 202, and 203 from the Josephson junction device 20 and the farthest point of the Josephson junction device 20 from each of the metal films 201, 202, and 203.

[0046] The metal films 201, 202, and 203 have different melting points. The material of the metal films 201, 202, and 203 is, for example, a Bi—Sn alloy. For example, the melting point of the metal film 201 is 140° C., the melting point of the metal film 202 is 200° C., and the melting point of the metal film 203 is 240° C. Furthermore, for example, the composition of the metal film 201 is 56% Bi by mass and 44% Sn by mass, the composition of the metal film 202 is 30% Bi by mass and 70% Sn by mass, and the composition of the metal film 203 is 90% Bi by mass and 10% Sn by mass. When irradiated with laser light, the temperatures of the metal films 201, 202, and 203 become approximately the same as the temperature of the temporary JJ element 20X. Therefore, when the temperature of the provisional JJ element 20X exceeds the melting point of the metal film 201, 202, or 203 during laser light irradiation, the metal film, whose temperature exceeds the melting point, melts and deforms irreversibly. This causes a change in the resistance of the metal film. For example, the resistance between both ends of the metal film in the X1-X2 direction changes. Depending on the degree of deformation, a disconnection may occur between both ends of the metal film in the X1-X2 direction. For example, when the temperature of the provisional JJ element 20X reaches 140°C or higher but lower than 200°C, the resistance of the metal film 201 changes, but the resistances of the metal films 202 and 203 do not. Furthermore, when the temperature of the provisional JJ element 20X reaches 200°C or higher but lower than 240°C, the resistances of the metal films 201 and 202 change, but the resistance of the metal film 203 does not change. Furthermore, when the temperature of the provisional JJ element 20X reaches 240°C or higher, the resistances of the metal films 201, 202, and 203 change. The metal film 201 is an example of a first temperature sensing structure, and the metal films 202 and 203 are an example of a second temperature sensing structure.

[0047] Next, a method for forming the metal films 201, 202, and 203 will be described. Figures 23 to 25 are plan views showing a method for forming the metal films 201, 202, and 203 in the second embodiment. Here, it is assumed that, before the metal films 201, 202, and 203 are formed, the lower superconducting film 11, the oxide film 14, the upper superconducting film 12, the lower superconducting film 21, the oxide film 24, and the upper superconducting film 22 have been formed in the same manner as in the first embodiment.

[0048] First, a mask 210 having openings 211 is formed on the substrate 50, the lower superconducting film 11, the oxide film 14, the upper superconducting film 12, the lower superconducting film 21, the oxide film 24, and the upper superconducting film 22. The openings 211 expose the regions of the substrate 50 where the metal film 201 is to be formed. In forming the mask 210, a photoresist is applied onto the substrate 50, and then the photoresist is exposed and developed.

[0049] 23, a 56 mass % Bi-44 mass % Sn alloy is evaporated from the Z1 side as viewed from the top surface of the substrate 50. As a result, a metal film 201 is formed on the substrate 50 within the opening 211.

[0050] Thereafter, the mask 210 is removed. The mask 210 can be removed by, for example, immersion in a stripping liquid or a solvent. When the metal film 201 is formed, 56 mass % Bi-44 mass % Sn alloy is deposited on the mask 210, but the deposit is removed together with the removal of the mask 210.

[0051] Next, a mask 220 having openings 221 is formed on the substrate 50, the lower superconducting film 11, the oxide film 14, the upper superconducting film 12, the lower superconducting film 21, the oxide film 24, the upper superconducting film 22, and the metal film 201. The openings 221 expose the regions of the substrate 50 where the metal film 202 is to be formed. In forming the mask 220, a photoresist is applied onto the substrate 50, and then the photoresist is exposed and developed.

[0052] 24, a 30 mass % Bi-70 mass % Sn alloy is vapor-deposited from the Z1 side as viewed from the top surface of the substrate 50. As a result, a metal film 202 is formed on the substrate 50 within the opening 221.

[0053] Thereafter, the mask 220 is removed. The mask 220 can be removed by, for example, immersion in a stripping liquid or a solvent. When the metal film 202 is formed, a 30 mass % Bi-70 mass % Sn alloy is deposited on the mask 220, but the deposit is removed together with the removal of the mask 220.

[0054] Subsequently, a mask 230 having openings 231 is formed on the substrate 50, the lower superconducting film 11, the oxide film 14, the upper superconducting film 12, the lower superconducting film 21, the oxide film 24, the upper superconducting film 22, the metal film 201, and the metal film 202. The openings 231 expose the regions of the substrate 50 where the metal film 203 is to be formed. In forming the mask 230, a photoresist is applied onto the substrate 50, and then the photoresist is exposed and developed.

[0055] 25, a 10 mass % Bi-90 mass % Sn alloy is vapor-deposited from the Z1 side as viewed from the top surface of the substrate 50. As a result, a metal film 203 is formed on the substrate 50 within the opening 231.

[0056] Thereafter, the mask 230 is removed. The mask 230 can be removed by, for example, immersion in a stripping liquid or a solvent. When the metal film 203 is formed, a 10 mass % Bi-90 mass % Sn alloy is attached to the mask 230, but the attached material is removed together with the removal of the mask 230.

[0057] In this manner, the metal films 201, 202 and 203 can be formed.

[0058] Other configurations of the second embodiment are similar to those of the first embodiment.

[0059] The second embodiment can also achieve the same effects as the first embodiment. Furthermore, the second embodiment can not only determine whether the provisional JJ elements 10X and 20X have reached a temperature equal to or higher than a certain threshold, but also estimate the temperature range reached by the provisional JJ elements 10X and 20X. For example, if the resistance value of the metal film 201 has changed but the resistance values ​​of the metal films 202 and 203 have not, the temperature reached by the provisional JJ elements 10X and 20X can be estimated to be 140°C or higher and lower than 200°C. Furthermore, if the resistance values ​​of the metal films 201 and 202 have changed but the resistance value of the metal film 203 has not, the temperature reached by the provisional JJ elements 10X and 20X can be estimated to be 200°C or higher and lower than 240°C. Furthermore, if the resistance values ​​of the metal films 201, 202, and 203 have changed, the temperature reached by the provisional JJ elements 10X and 20X can be estimated to be 240°C or higher.

[0060] The material of the metal films 201, 202 and 203 may be a Sn--Pb alloy or the like.

[0061] Third Embodiment Next, a third embodiment will be described. The third embodiment differs from the first embodiment mainly in the configuration of the temperature detection structure. Fig. 26 is a plan view showing a temperature detection structure included in a quantum device according to the third embodiment.

[0062] In the quantum device according to the third embodiment, as shown in FIG. 26 , the test region 52 has metal films 301 and 302 instead of the metal film 101. The metal films 301 and 302 are provided near the Josephson junction elements 20 in a plan view. The metal film 301 has, for example, a thin wire shape extending parallel to the X1-X2 direction, and the metal film 302 has, for example, a thin wire shape extending parallel to the Y1-Y2 direction. The dimensions (thickness) of the metal films 301 and 302 in the Z1-Z2 direction are, for example, 0.1 μm or more and 1.0 μm or less. The dimension (width) of the narrowest portion of the metal film 301 in the Y1-Y2 direction is, for example, 1 μm or more and 10 μm or less, and the dimension (width) of the narrowest portion of the metal film 302 in the X1-X2 direction is, for example, 1 μm or more and 10 μm or less. The first distance between each of the metal films 301 and 302 and the Josephson junction element 20 is equal to or less than the radius of the spot of the laser light irradiated on the Josephson junction element 20, for example, 100 μm or less. The first distance is preferably equal to or less than 80 μm, and more preferably equal to or less than 60 μm. Here, the first distance between each of the metal films 301 and 302 and the Josephson junction element 20 is the distance between the farthest point of each of the metal films 301 and 302 from the Josephson junction element 20 and the farthest point of each of the Josephson junction element 20 from the metal films 301 and 302. The X-axis is an example of the first axis, and the Y-axis is an example of the second axis.

[0063] The metal films 301 and 302 have different melting points. For example, the melting point of the metal film 301 is 140° C., and the melting point of the metal film 302 is 200° C. For example, the metal film 301 is made of the same material as the metal film 201, and the metal film 302 is made of the same material as the metal film 202. The metal film 301 is an example of a first temperature detection structure, and the metal film 302 is an example of a second temperature detection structure.

[0064] Next, a method for forming the metal films 301 and 302 will be described. Figures 27 and 28 are plan views showing a method for forming the metal films 301 and 302 in the third embodiment. Here, it is assumed that the lower superconducting film 11, the oxide film 14, the upper superconducting film 12, the lower superconducting film 21, the oxide film 24, and the upper superconducting film 22 have been formed in the same manner as in the first embodiment, before the metal films 301 and 302 are formed.

[0065] 27, a mask 310 having openings 311 and 312 is formed on the substrate 50, the lower superconducting film 11, the oxide film 14, the upper superconducting film 12, the lower superconducting film 21, the oxide film 24, and the upper superconducting film 22. The opening 311 exposes a region of the substrate 50 where the metal film 301 is to be formed. The opening 312 exposes a region of the substrate 50 where the metal film 302 is to be formed. In forming the mask 310, a photoresist is applied onto the substrate 50, and then the photoresist is exposed and developed.

[0066] Next, a 56 mass % Bi-44 mass % Sn alloy is vapor-deposited from a direction tilted from the Z1 side toward the X1 or X2 side when viewed from the top surface of the substrate 50. As a result, a metal film 301 is formed on the substrate 50 within the opening 311.

[0067] 28, a 30 mass % Bi-70 mass % Sn alloy is vapor-deposited from a direction tilted from the Z1 side toward the Y1 or Y2 side when viewed from the top surface of the substrate 50. As a result, a metal film 302 is formed on the substrate 50 within the opening 312. The metal film 302 can be formed, for example, in the film formation chamber in which the metal film 301 was formed.

[0068] Subsequently, the mask 310 is removed. The mask 310 can be removed by, for example, immersion in a remover or a solvent. When the metal film 301 and the metal film 302 are formed, a Bi—Sn alloy adheres to the mask 310, but the adhered material is removed together with the removal of the mask 310.

[0069] In this manner, the metal films 301 and 302 can be formed.

[0070] Other configurations of the third embodiment are similar to those of the first embodiment.

[0071] The third embodiment can also achieve the same effects as the first embodiment. Furthermore, similar to the second embodiment, the third embodiment not only makes it possible to determine whether the provisional JJ elements 10X and 20X have reached a temperature equal to or higher than a certain threshold, but also makes it possible to estimate the temperature range reached by the provisional JJ elements 10X and 20X.

[0072] Furthermore, in the third embodiment, the metal films 301 and 302 can be formed using one mask 310 .

[0073] The material of the metal films 301 and 302 may be a Sn--Pb alloy or the like.

[0074] Fourth Embodiment Next, a fourth embodiment will be described. The fourth embodiment differs from the first embodiment mainly in the configuration of the temperature detection structure. Fig. 29 is a plan view showing a temperature detection structure included in a quantum device according to the fourth embodiment.

[0075] 29 , in the quantum device according to the fourth embodiment, the test region 52 has metal films 401 and 402 instead of the metal film 101. The metal films 401 and 402 are provided near the Josephson junction elements 20 in a plan view. The metal film 401 has a thin wire shape extending parallel to a third axis 33 rotated 45 degrees counterclockwise from the X1-X2 direction, for example, and the metal film 402 has a thin wire shape extending parallel to a fourth axis 34 rotated 45 degrees clockwise from the X1-X2 direction, for example. The dimension (thickness) of the metal films 401 and 402 in the Z1-Z2 direction is, for example, 0.1 μm or more and 1.0 μm or less. The dimension (width) of the narrowest portion of the metal film 401 in a direction parallel to the fourth axis 34 is, for example, 1 μm or more and 10 μm or less, and the dimension (width) of the narrowest portion of the metal film 402 in a direction parallel to the third axis 33 is, for example, 1 μm or more and 10 μm or less. A first distance between each of the metal films 401 and 402 and the Josephson junction element 20 is equal to or less than the radius of the spot of the laser light irradiated on the Josephson junction element 20, for example, 100 μm or less. The first distance is preferably 80 μm or less, and more preferably 60 μm or less. Here, the first distance between each of the metal films 401 and 402 and the Josephson junction element 20 is the distance between the farthest point of each of the metal films 401 and 402 from the Josephson junction element 20 and the farthest point of the Josephson junction element 20 from each of the metal films 401 and 402.

[0076] The metal films 401 and 402 have different melting points. For example, the melting point of the metal film 401 is 140° C., and the melting point of the metal film 402 is 200° C. For example, the metal film 401 is made of the same material as the metal film 201, and the metal film 402 is made of the same material as the metal film 202. The metal film 401 is an example of a first temperature detection structure, and the metal film 402 is an example of a second temperature detection structure.

[0077] Next, a method for forming the metal films 401 and 402 will be described. Figures 30 to 34 are plan views showing a method for forming the metal films 401 and 402 in the fourth embodiment. Although some illustrations are omitted here, the methods for forming the lower superconducting film 11, the oxide film 14, the upper superconducting film 12, the lower superconducting film 21, the oxide film 24, and the upper superconducting film 22 will be described.

[0078] First, as shown in Fig. 30, a mask 410 having openings 111 (see Fig. 15), 112, 421, and 422 is formed on a substrate 50. The opening 111 exposes a region of the substrate 50 where the lower superconducting film 11 and the upper superconducting film 12 are to be formed. The opening 112 exposes a region of the substrate 50 where the lower superconducting film 21 and the upper superconducting film 22 are to be formed. The opening 421 exposes a region of the substrate 50 where the metal film 401 is to be formed. The opening 422 exposes a region of the substrate 50 where the metal film 402 is to be formed. In forming the mask 410, a photoresist is applied onto the substrate 50, and then the photoresist is exposed and developed.

[0079] Next, oblique deposition of aluminum is performed from a direction tilted from the Z1 side to the X2 side when viewed from the top surface of the substrate 50. As a result, a lower superconducting film 11 is formed on the substrate 50 within the opening 111, and a lower superconducting film 21 is formed on the substrate 50 within the opening 112 (see FIG. 16 ). Oblique deposition may also be performed from a direction tilted from the Z1 side to the X1 side when viewed from the top surface of the substrate 50.

[0080] 31, the upper surfaces of the lower superconducting films 11 and 21 are oxidized. As a result, an oxide film 14 is formed on the upper surface of the lower superconducting film 11 (see FIG. 17), and an oxide film 24 is formed on the upper surface of the lower superconducting film 21.

[0081] 32, aluminum or niobium is obliquely evaporated from a direction inclined from the Z1 side to the Y1 side when viewed from the top surface of the substrate 50. As a result, an upper superconducting film 12 is formed on the substrate 50 and the oxide film 14 in the opening 111 (see FIG. 18), and an upper superconducting film 22 is formed on the substrate 50 and the oxide film 24 in the opening 112. The oblique evaporation may also be performed from a direction inclined from the Z1 side to the Y2 side when viewed from the top surface of the substrate 50. The upper superconducting films 12 and 22 can be formed, for example, in the film formation chamber in which the oxide films 23 and 24 are formed.

[0082] 33, a 56 mass % Bi-44 mass % Sn alloy is obliquely vapor deposited from a direction inclined from the Z1 side toward a direction parallel to the third axis 33 when viewed from the top surface of the substrate 50. As a result, a metal film 401 is formed on the substrate 50 within the opening 421. The metal film 401 can be formed, for example, in the film formation chamber in which the upper superconducting films 12 and 22 are formed.

[0083] 34, oblique vapor deposition of a 30 mass % Bi-70 mass % Sn alloy is performed from a direction tilted from the Z1 side toward a direction parallel to the fourth axis 34 when viewed from the top surface of the substrate 50. As a result, a metal film 402 is formed on the substrate 50 within the opening 422. The metal film 402 can be formed, for example, in the film formation chamber in which the metal film 401 is formed.

[0084] Subsequently, the mask 410 is removed. The mask 410 can be removed by, for example, immersing it in a remover or a solvent. Substances deposited during the formation of the lower superconducting films 11 and 21 adhere to the mask 410, but the adhered substances are removed together with the removal of the mask 410.

[0085] In this manner, the metal films 401 and 402 can be formed.

[0086] Other configurations of the fourth embodiment are similar to those of the first embodiment.

[0087] The fourth embodiment can also achieve the same effects as the first embodiment. Furthermore, similar to the second embodiment, the fourth embodiment can not only determine whether the provisional JJ elements 10X and 20X have reached a temperature equal to or higher than a certain threshold, but also estimate the temperature range reached by the provisional JJ elements 10X and 20X.

[0088] Furthermore, in the fourth embodiment, the lower superconducting films 11 and 21, the upper superconducting films 12 and 22, the oxide films 14 and 24, and the metal films 401 and 402 can be formed using one mask 410.

[0089] The material of the metal films 401 and 402 may be a Sn--Pb alloy or the like.

[0090] Fifth Embodiment Next, a fifth embodiment will be described. The fifth embodiment differs from the first embodiment mainly in the configuration of the temperature detection structure. FIG. 35 is a plan view showing a temperature detection structure included in a quantum device according to a fourth embodiment. FIG. 36 is a cross-sectional view showing a temperature detection structure included in a quantum device according to the fourth embodiment. FIG. 36 corresponds to a cross-sectional view taken along line III-III in FIG. 35.

[0091] In the quantum device according to the fifth embodiment, as shown in FIGS. 35 and 36 , the test region 52 has a metal film 500 instead of the metal film 101. The metal film 500 is provided near the Josephson junction element 20 in a plan view. The metal film 500 has, for example, a thin wire shape extending parallel to the X1-X2 direction. The metal film 500 has a beam portion 501 spaced from the substrate 50 and support portions 502 and 503 that support the beam portion 501 on the substrate 50. The support portion 502 is connected to the end of the beam portion 501 on the X2 side, and the support portion 503 is connected to the end of the beam portion 501 on the X1 side. The dimension (thickness) of the beam portion 501 in the Z1-Z2 direction is, for example, 0.3 μm or more and 1.0 μm or less. The dimension (width) of the narrowest portion of the beam portion 501 in the Y1-Y2 direction is, for example, 1 μm or more and 10 μm or less. The first distance between the beam 501 and the Josephson element 20 is equal to or less than the radius of the spot of the laser light irradiated on the Josephson element 20, for example, 100 μm or less. The first distance is preferably equal to or less than 80 μm, and more preferably equal to or less than 60 μm. Here, the first distance between the beam 501 and the Josephson element 20 is the distance between the farthest point of the beam 501 from the Josephson element 20 and the farthest point of the Josephson element 20 from the beam 501.

[0092] For example, the metal film 500 is made of the same material as the metal film 101. The metal film 500 is an example of a first temperature sensing structure.

[0093] Next, a method for forming the metal film 500 will be described. Figures 37 to 39 are diagrams showing a method for forming the metal film 500 in the fifth embodiment. Figures 37(a) to 39(a) are plan views. Figures 37(b) to 39(b) correspond to cross-sectional views taken along line III-III in Figures 37(a) to 39(a), respectively. Here, it is assumed that, before forming the metal film 500, the lower superconducting film 11, the oxide film 14, the upper superconducting film 12, the lower superconducting film 21, the oxide film 24, and the upper superconducting film 22 have been formed in the same manner as in the first embodiment.

[0094] 37 , a mask 510 having openings 511 and 512 is formed on the substrate 50, the lower superconducting film 11, the oxide film 14, the upper superconducting film 12, the lower superconducting film 21, the oxide film 24, and the upper superconducting film 22. The opening 511 exposes a region of the substrate 50 where the support portion 502 is to be formed. The opening 512 exposes a region of the substrate 50 where the support portion 503 is to be formed. In forming the mask 510, a photoresist is applied onto the substrate 50, and then the photoresist is exposed and developed.

[0095] 38 , a mask 520 having openings 521 is formed on the mask 510. The openings 511 and 512 of the mask 510 and the region of the mask 510 where the beam portions 501 are to be formed are exposed from the openings 521. In forming the mask 520, a photoresist is applied onto the mask 510, and then the photoresist is exposed and developed.

[0096] 39, a Sn—Pb alloy or a Bi—Sn alloy is then vapor-deposited onto the substrate 50. At this time, oblique vapor deposition may be performed from a direction tilted from the Z1 side toward the X2 side or from the Z1 side toward the X1 side. This improves the coverage of the Sn—Pb alloy or the Bi—Sn alloy on the sidewall of the mask 510. As a result, a support portion 502 is formed on the substrate 50 within the opening 511, a support portion 503 is formed on the substrate 50 within the opening 512, and a beam portion 501 is formed on the mask 510 within the opening 521.

[0097] Subsequently, the mask 510 is removed. The mask 510 can be removed by, for example, immersion in a stripping solution or a solvent. When the metal film 500 is formed, the deposited material, such as a Sn—Pb alloy or a Bi—Sn alloy, adheres to the mask 510, but the adhered material is removed together with the removal of the mask 510.

[0098] In this manner, the metal film 500 can be formed.

[0099] Other configurations of the fifth embodiment are similar to those of the first embodiment.

[0100] The fifth embodiment can also achieve the same effects as the first embodiment. In addition, in the fifth embodiment, the beam portions 501 of the metal film 500 are spaced apart from the substrate 50, and therefore are easily deformed when heated above their melting points, and the deformation is easily confirmed visually.

[0101] In the second, third, or fourth embodiment, each metal film may have the same shape as the metal film 500 .

[0102] Sixth Embodiment Next, a sixth embodiment will be described. The sixth embodiment differs from the first embodiment mainly in the arrangement of the test region. Fig. 40 is a diagram showing the layout of a quantum device according to the sixth embodiment.

[0103] 40, in the quantum device 6 according to the sixth embodiment, the peripheral region 42 has fewer test regions 52 than functional regions 51, here two test regions 52. One test region 52 is disposed adjacent to two functional regions 51 aligned parallel to each other in the Y1-Y2 direction on the X2 side, and the other test region 52 is disposed adjacent to two functional regions 51 aligned parallel to each other in the Y1-Y2 direction on the X1 side. The other configuration of the sixth embodiment is similar to that of the first embodiment.

[0104] The sixth embodiment can also provide the same effects as the first embodiment.

[0105] Seventh Embodiment Next, a seventh embodiment will be described. The seventh embodiment differs from the first embodiment mainly in the arrangement of the test region. Fig. 41 is a diagram showing the layout of a quantum device according to the seventh embodiment.

[0106] 41, in the quantum device 7 according to the seventh embodiment, one test region 52 is surrounded by four function regions 51. Other configurations of the seventh embodiment are similar to those of the first embodiment.

[0107] The seventh embodiment can also provide the same effects as the first embodiment.

[0108] Eighth Embodiment Next, an eighth embodiment will be described. The eighth embodiment relates to a quantum device. Fig. 42 is a diagram showing the layout of a quantum device according to the eighth embodiment.

[0109] As shown in FIG. 42 , the quantum device 8 according to the eighth embodiment has a central region 61 and a peripheral region 62. In a plan view, the central region 61 is surrounded by the peripheral region 62. The central region 61 has, for example, one quantum bit region 71 and four auxiliary quantum bit regions 73. The quantum bit region 71 has a square planar shape, with two sides parallel to the X1-X2 direction and two sides parallel to the Y1-Y2 direction. The four auxiliary quantum bit regions 73 also have a square planar shape, and each of the four auxiliary quantum bit regions 73 is in contact with one of the sides of the quantum bit region 71. The peripheral region 62 also has four test regions 72. The four test regions 72 each have a square planar shape, and each of the four test regions 72 is in contact with two auxiliary quantum bit regions 73.

[0110] The quantum bit region 71 and the auxiliary quantum bit region 73, like the functional region 51, each have a Josephson junction element 10 and a capacitor 60. For example, the quantum bit region 71 includes a main quantum bit used in calculations, and the auxiliary quantum bit region 73 includes an auxiliary quantum bit (ancilla) that functions as a temporary memory during calculations. The test region 72, like the test region 52, has a Josephson junction element 20 and a metal film 101. The Josephson junction element 10 included in the auxiliary quantum bit region 73 is an example of a third Josephson junction element.

[0111] The eighth embodiment can also achieve the same effects as the first embodiment. Furthermore, the auxiliary quantum bits included in auxiliary quantum bit region 73 do not require quantum performance as high as that of the quantum bits included in quantum bit region 71. For example, the coherence time of the auxiliary quantum bits included in auxiliary quantum bit region 73 may be made shorter than that of the quantum bits included in quantum bit region 71 by irradiation with laser light.

[0112] In the present disclosure, the material of the temperature detection structure is not limited to metal.

[0113] Quantum devices according to the present disclosure can be used, for example, in quantum computing.

[0114] Although the preferred embodiments have been described in detail above, the present disclosure is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0115] 1, 6, 7, 8: quantum device 10, 20: Josephson junction element 10X, 20X: provisional Josephson junction element 11, 21: lower superconducting film 12, 22: upper superconducting film 13, 13X, 23, 23X: oxide film 25: laser light 30: temperature detection region 50: substrate 70: transmon 101, 201, 202, 203, 301, 302, 401, 402, 500: metal film 501: beam portion 502, 503: support portion

Claims

1. A quantum device comprising: a first Josephson junction element formed on a substrate; a second Josephson junction element and a first temperature detection structure formed in a first region of the substrate; the first Josephson junction element having first and second superconducting films, and a first oxide film provided between the first and second superconducting films; the second Josephson junction element having third and fourth superconducting films, and a second oxide film provided between the third and fourth superconducting films; and the first temperature detection structure irreversibly deforms at a first temperature lower than a temperature at which the superconducting characteristics of the third or fourth superconducting film change.

2. The quantum device according to claim 1, wherein the first temperature is between 140°C and 190°C.

3. The quantum device according to claim 1 or 2, wherein the first temperature detection structure comprises a first metal film.

4. The quantum device according to claim 3, wherein the material of the first metal film is a tin-lead alloy or a bismuth-tin alloy.

5. The quantum device according to claim 3, wherein the first metal film has a beam portion spaced from the substrate, and a support portion that supports the beam portion on the substrate.

6. A quantum device as claimed in claim 1 or 2, characterized in that the first region has a second temperature sensing structure which irreversibly deforms at a second temperature higher than the first temperature.

7. The quantum device of claim 6, wherein the second temperature sensing structure comprises a second metal film.

8. The quantum device described in claim 1 or 2, characterized in that the first temperature detection structure has a first metal film and a second metal film that irreversibly deforms at a second temperature higher than the first temperature, and in a planar view, the first metal film extends parallel to a first axis, and the second metal film extends parallel to a second axis different from the first axis.

9. The quantum device of claim 8, wherein the first axis and the second axis are mutually orthogonal.

10. The quantum device of claim 9, wherein, in a planar view, the first superconducting film, the second superconducting film, the third superconducting film and the fourth superconducting film extend parallel to a direction tilted 45 degrees from the first axis or the second axis.

11. A quantum device as described in claim 1 or 2, characterized in that the first superconducting film and the third superconducting film are made of a common material, the second superconducting film and the fourth superconducting film are made of a common material, the first oxide film and the second oxide film are made of a common material, and the thickness of the second oxide film is 99% or more and 101% or less of the thickness of the first oxide film.

12. The quantum device according to claim 1 or 2, wherein the distance between the first temperature detection structure and the second Josephson junction element is 100 μm or less.

13. The quantum device according to claim 1 or 2, further comprising a circuit including the first Josephson junction element.

14. The quantum device according to claim 1 or 2, further comprising a third Josephson junction element joined to the first Josephson junction element, and the first temperature detection structure and the second Josephson junction element are arranged closer to the third Josephson junction element than to the first Josephson junction element.

15. A process for simultaneously forming a first superconducting film and a third superconducting film; a process for simultaneously oxidizing the first superconducting film and the third superconducting film to form a third oxide film on a surface of the first superconducting film and a fourth oxide film on a surface of the third superconducting film; a process for simultaneously forming a second superconducting film sandwiching the third oxide film between the first superconducting film and the second superconducting film and a fourth superconducting film sandwiching the fourth oxide film between the third superconducting film and the second superconducting film; a process for forming a first temperature detection structure that irreversibly deforms at a first temperature that is lower than a temperature at which the superconducting characteristics of the third superconducting film or the fourth superconducting film change; a process for irradiating a first Josephson junction element including the first superconducting film, the third oxide film, and the second superconducting film with a first laser light, and a process for simultaneously irradiating a second Josephson junction element including the third superconducting film, the fourth oxide film, and the fourth superconducting film and the first temperature detection structure with a second laser light. and checking whether or not the first temperature detection structure is deformed before and after the irradiation of the second laser light, wherein the power and time of the laser light irradiation to the first Josephson junction element and the laser light irradiation to the second Josephson junction element and the first temperature detection structure are equal.

16. The method for manufacturing a quantum device according to claim 15, wherein the presence or absence of the deformation is confirmed based on a change in electrical resistance.

17. A method for inspecting a quantum device comprising: a first tentative Josephson element formed on a substrate; and a second tentative Josephson element and a first temperature detection structure formed in a first region of the substrate, the first tentative Josephson element comprising first and second superconducting films, and a third oxide film provided between the first and second superconducting films, the second tentative Josephson element comprising third and fourth superconducting films, and a fourth oxide film provided between the third and fourth superconducting films, the first temperature detection structure irreversibly deforming at a first temperature lower than a temperature at which the superconducting characteristics of the third or fourth superconducting film change, the method comprising the steps of: irradiating the first tentative Josephson element with laser light to increase the degree of oxidation of the third oxide film, and irradiating the second tentative Josephson element and the first temperature detection structure simultaneously with laser light to increase the degree of oxidation of the fourth oxide film; and confirming whether or not the first temperature detection structure is deformed before and after the irradiation with the laser light.

18. The method for inspecting a quantum device according to claim 17, wherein the presence or absence of the deformation is confirmed based on a change in electrical resistance.

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