Superconducting quantum circuit, quantum device, and method of manufacturing superconducting quantum circuit

Abstract

To surely connect a main pattern formed on a substrate to a first conductor pattern riding on the main pattern in a superconducting quantum circuit.SOLUTION: A superconducting quantum circuit includes a substrate, a pair of main patterns, a pair of first conductor patterns, a pair of second conductor patterns, and a Josephson junction portion, boundary lines between the substrate and the pair of main patterns in plan view include a facing boundary line and a non-facing boundary line, the facing boundary line being located on a side where the pair of main patterns face each other in a first direction, the non-facing boundary line being other than the facing boundary line, and the pair of first conductor patterns include a mounted portion that is mounted on the pair of main patterns from the substrate. The piled portion is formed to overlap at least the non-facing boundary line.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to superconducting quantum circuits, quantum devices, and methods for fabricating superconducting quantum circuits. [Background technology]

[0002] It is known that superconducting quantum circuits are used in quantum devices mounted on quantum computers and the like. For example, Patent Document 1 discloses a superconducting quantum circuit having a plurality of first conductors formed in layers of a superconducting material, a plurality of second conductors formed of a superconducting material and at least a portion of which is stacked on the first conductors, and a conductor layer formed of a superconducting material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 118464 Summary of the Invention [Problem to be solved by the invention]

[0004] In the superconducting quantum circuit disclosed in Patent Document 1, a first conductor is formed on a conductor layer formed on a substrate by oblique deposition (first time) from a first direction through a resist mask. Then, an oxide film is formed on the surface of the first conductor, and a second conductor is formed on the first conductor by oblique deposition (second time) from a second direction through the resist mask. This forms a Josephson junction between the first conductor and the second conductor via the oxide film. However, since the conductor layer has a predetermined thickness, a step occurs at the boundary between the substrate and the conductor layer. Depending on the size of this step, the first conductor may not be deposited properly at the boundary of the conductor layer. Therefore, there is room for improvement regarding the connection between the conductor layer and the first conductor.

[0005] An object of the present disclosure is to provide a superconducting quantum circuit, a quantum device, and a method for manufacturing a superconducting quantum circuit that solves the above problems. [Means for solving the problem]

[0006] To solve the above problems, this disclosure proposes the following means. A superconducting quantum circuit according to the present disclosure comprises a substrate and a laminate of superconducting materials formed on the substrate, the laminate comprising a pair of main patterns formed on the substrate and spaced apart in a first direction, and a connection pattern formed on the substrate and the pair of main patterns and connecting the pair of main patterns, the connection pattern comprising a pair of first conductor patterns extending in the first direction and having a first gap separating them in the first direction and having an oxide film formed on a surface thereof, and a second gap extending in the first direction and having a second gap separating them in the first direction and shifted in the first direction to straddle the first gap and overlapping the pair of first conductor patterns. a pair of second conductor patterns; and a Josephson junction located between the first gap and the second gap in a planar view, and formed by one of the pair of first conductor patterns and one of the pair of second conductor patterns overlapping with each other via the oxide film, wherein the boundary between the substrate and the pair of main patterns in a planar view includes opposing boundary lines located on the sides where the pair of main patterns face each other in the first direction, and non-opposing boundary lines other than the opposing boundary lines, and the pair of first conductor patterns have riding-up portions that ride-up from the substrate onto the pair of main patterns, and the riding-up portions are formed to overlap at least the non-opposing boundary lines.

[0007] A quantum device according to the present disclosure includes the above superconducting quantum circuit.

[0008] Furthermore, a method for manufacturing a superconducting quantum circuit according to the present disclosure comprises a laminate formation step of forming a laminate of superconducting material on a substrate, the laminate formation step comprising: a main pattern formation step of forming a pair of main patterns spaced apart in a first direction on the substrate; and a connection pattern formation step of forming a connection pattern on the substrate and the pair of main patterns to connect the pair of main patterns, the connection pattern formation step comprising: a first conductor pattern formation step of forming a pair of first conductor patterns extending in the first direction and having a first gap portion spaced apart in the first direction by a first oblique vapor deposition from one side in the first direction using a mask having a pair of openings spaced apart in the first direction; an oxide film formation step of forming an oxide film on surfaces of the pair of first conductor patterns; and a second oblique vapor deposition from the other side in the first direction using the mask to form a connection pattern extending in the first direction. and a second conductor pattern forming process in which a pair of second conductor patterns having a second gap that separates them in the first direction are formed overlapping the pair of first conductor patterns, shifted in the first direction so as to straddle the first gap, and a Josephson junction is formed between the first gap and the second gap in a planar view, via the oxide film, where one of the pair of first conductor patterns and one of the pair of second conductor patterns overlap, wherein the boundary lines between the substrate and the pair of main patterns in a planar view include opposing boundary lines located on sides where the pair of main patterns face each other in the first direction, and non-opposing boundary lines other than the opposing boundary lines, and in the first conductor pattern forming process, the pair of first conductor patterns form riding-up portions that ride-up from the substrate onto the pair of main patterns, and the riding-up portions are formed to overlap at least the non-opposing boundary lines. [Effects of the Invention]

[0009] According to the present disclosure, the main pattern formed on the substrate and the first conductor pattern that runs over the main pattern can be reliably connected. [Brief explanation of the drawings]

[0010] [Figure 1]FIG. 1 is a plan view of a superconducting quantum circuit according to an example of a minimum configuration of the present disclosure. [Figure 2] FIG. 1 is a plan view of a superconducting quantum circuit according to a first embodiment of the present disclosure. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III shown in FIG. 2. [Figure 4] FIG. 4 is an enlarged plan view of an area A shown in FIG. [Figure 5] 1A to 1C are process diagrams illustrating a method for manufacturing a superconducting quantum circuit according to a first embodiment of the present disclosure. [Figure 6] 1A to 1C are process diagrams illustrating a method for manufacturing a superconducting quantum circuit according to a first embodiment of the present disclosure. [Figure 7] 1A to 1C are process diagrams illustrating a method for manufacturing a superconducting quantum circuit according to a first embodiment of the present disclosure. [Figure 8] FIG. 10 is a plan view of a superconducting quantum circuit according to a second embodiment of the present disclosure. [Figure 9] FIG. 10 is an enlarged plan view of a main part of a superconducting quantum circuit according to a second embodiment of the present disclosure. [Figure 10] FIG. 10 is a plan view of a superconducting quantum circuit according to a third embodiment of the present disclosure. [Figure 11] FIG. 10 is an enlarged plan view of a main part of a superconducting quantum circuit according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] An example of the minimum configuration of the present disclosure will be described with reference to FIG. Fig. 1 is a plan view of a superconducting quantum circuit 1 according to an example of a minimum configuration of the present disclosure. In Fig. 1, in addition to the entire superconducting quantum circuit 1, a portion thereof is illustrated enlarged. For ease of explanation, the plan view is illustrated so that the first conductor pattern 30 underneath the second conductor pattern 40 is visible where the first conductor pattern 30 and the second conductor pattern 40 overlap. This is also true for the other plan views. As shown in FIG. 1, a superconducting quantum circuit 1 includes a substrate 2 and a stack 3 of superconducting materials formed on the substrate 2.

[0012] The laminate 3 includes a pair of main patterns 10 formed spaced apart on the substrate 2, and a connection pattern 20 formed on the substrate 2 and the pair of main patterns 10, connecting the pair of main patterns 10. The connection pattern 20 forms, for example, a superconducting quantum interference device (SQUID). The pair of main patterns 10 is, for example, a resonant circuit, and is connected to the connection pattern 20.

[0013] In the following description, an XYZ Cartesian coordinate system is set, and the positional relationship of each component may be described with reference to this XYZ Cartesian coordinate system. A first direction along the surface of the substrate 2, in which a pair of main patterns 10 are spaced apart and face each other, is defined as the X-axis direction. A second direction along the surface of the substrate 2 that is orthogonal to the X-axis direction is defined as the Y-axis direction. A third direction perpendicular to the surface of the substrate 2 is defined as the Z-axis direction.

[0014] In the drawings, the side toward which the arrow in the X-axis direction points is the +X side, and the side facing the opposite direction is the -X side. In addition, the side toward which the arrow in the Y-axis direction points is the +Y side, and the side facing the opposite direction is the -Y side. In addition, the side toward which the arrow in the Z-axis direction points is the +Z side, and the side facing the opposite direction is the -Z side. For ease of explanation, the +Z side is referred to as the upper side and the -Z side is referred to as the lower side, but the Z-axis direction does not have to coincide with the direction of gravity.

[0015] The connection pattern 20 includes a first conductor pattern 30, a second conductor pattern 40, and a Josephson junction 50. A pair of first conductor patterns 30 are formed on the substrate 2 and the pair of main patterns 10. The pair of first conductor patterns 30 extend in the X-axis direction and have first gaps 31 spaced apart in the X-axis direction. An oxide film 30a is formed on the surfaces of the pair of first conductor patterns 30.

[0016] The second conductor patterns 40 are formed in pairs on the substrate 2, the pair of main patterns 10, and the pair of first conductor patterns 30. The pair of second conductor patterns 40 extend in the X-axis direction and have second gaps 41 spaced apart in the X-axis direction. The pair of second conductor patterns 40 have substantially the same patterns as the pair of first conductor patterns 30, but are shifted in the X-axis direction and overlap the pair of first conductor patterns 30 so as to straddle the first gaps 31.

[0017] The Josephson junction 50 is located between the first gap 31 and the second gap 41 in plan view, and is formed by overlapping one of the pair of first conductor patterns 30 (the first conductor pattern 30 arranged on the -X side) and one of the pair of second conductor patterns 40 (the second conductor pattern 40 arranged on the +X side) via the oxide film 30a.

[0018] In plan view, a step corresponding to the thickness of the main patterns 10 is formed at a boundary line 100 between the substrate 2 and the pair of main patterns 10. The pair of first conductor patterns 30 includes a riding portion 33 that rides from the substrate 2 onto the pair of main patterns 10.

[0019] Boundary line 100 includes opposing boundary lines 101 located on the sides where a pair of main patterns 10 face each other in the X-axis direction, and non-opposing boundary lines 102 other than opposing boundary lines 101. For example, in the case of rectangular boundary line 100 surrounding main pattern 10 located on the -X side, one side located on the +X side and extending in the Y-axis direction is opposing boundary line 101, and the other three sides are non-opposing boundary lines 102.

[0020] The riding-up portion 33 is formed so as to overlap at least the non-opposing boundary line 102. As will be described later, when forming the first conductor pattern 30 by oblique vapor deposition from one side (-X side) to the other side (+X side) in the X-axis direction, for example, at the opposing boundary line 101 portion of the main pattern 10 located on the -X side, the step of the main pattern 10 may cast a shadow, possibly preventing the first conductor pattern 30 from being formed properly, whereas this is less likely at the non-opposing boundary line 102 portion.

[0021] According to the above-described superconducting quantum circuit 1, the overhanging portion 33 is formed so as to overlap at least the non-facing boundary line 102 and has a connection structure via the non-facing boundary line 102, thereby enabling a reliable connection between the main pattern 10 formed on the substrate 2 and the first conductor pattern 30 overhanging the main pattern 10. Furthermore, according to a quantum device including this superconducting quantum circuit 1, the superconducting quantum circuit 1 functions normally, and therefore deviations in characteristics from the design can be suppressed. Furthermore, in plan view, the direction of current flow and the direction of obliquely depositing the first conductor pattern 30 and the second conductor pattern 40 are aligned in the X-axis direction in the superconducting quantum circuit 1. Therefore, according to the manufacturing method for the superconducting quantum circuit 1, the number of manufacturing processes can be reduced compared to a manufacturing method in which the first conductor pattern 30 and the second conductor pattern 40 are obliquely deposited from a direction different from the X-axis direction, and the size of the superconducting quantum circuit 1 in the Y-axis direction can be reduced.

[0022] Next, a first embodiment of the present disclosure will be described with reference to Figures 2 to 7 in addition to Figure 1. In Figures 2 to 7, the same components as those in Figure 1 are denoted by the same reference numerals, and the description will be simplified.

[0023] (First embodiment) Fig. 2 is a plan view of the superconducting quantum circuit 1 according to the first embodiment of the present disclosure. Fig. 3 is a cross-sectional view taken along III-III shown in Fig. 2. Fig. 4 is an enlarged plan view of region A shown in Fig. 3. 2, the superconducting quantum circuit 1 includes a substrate 2 and a laminate 3. The laminate 3 includes a pair of main patterns 10 and a connection pattern 20.

[0024] 2 includes a pair of first conductor patterns 30 and a pair of second conductor patterns 40 each formed in an L-shape in plan view. By forming each of the pair of first conductor patterns 30 and the pair of second conductor patterns 40 in an L-shape in plan view in this way and overlapping the L-shaped bent portions, a Josephson junction 50 can be stably formed.

[0025] 2, the connection pattern 20 is separated in the Y-axis direction, but it does not have to be separated in the Y-axis direction. For example, both ends of the connection pattern 20 in the X-axis direction may be connected by a pattern extending in the Y-axis direction, resulting in a rectangular shape as a whole. However, in this case, the wiring area of ​​the connection pattern 20 will increase.

[0026] As will be described later, the location where the connection pattern 20 is formed is the portion to be etched. For example, if the oxide film on the surface of the substrate 2 or the surface of the main pattern 10 is removed by RF etching or the like before the first conductor pattern 30 is formed, the etched portions will have increased surface roughness and defects in the crystal structure, which will cause losses in the superconducting quantum circuit 1.

[0027] 2, by separating the connection pattern 20 in the Y-axis direction and reducing the wiring area of ​​the connection pattern 20, it is possible to reduce the loss factors of the superconducting quantum circuit 1. On the other hand, if the wiring area of ​​the connection pattern 20 is reduced, the tunneling current between the main pattern 10 and the connection pattern 20 will become smaller. Therefore, unless the main pattern 10 and the connection pattern 20 are securely connected, unintended parts will behave as Josephson junctions, which will cause the characteristics of the superconducting quantum circuit 1 to deviate from the design.

[0028] The substrate 2 is made of, for example, silicon, sapphire, a compound semiconductor, or the like. The substrate 2 may also be made of a single crystal, a polycrystal, an amorphous, or the like. The substrate 2 may also be a high-resistance semiconductor substrate.

[0029] 3, a main pattern 10, a first conductor pattern 30, and a second conductor pattern 40 are laminated on a substrate 2. The main pattern 10 is formed on a first layer of a laminate 3. The first conductor pattern 30 is formed on a second layer of the laminate 3. The second conductor pattern 40 is formed on a third layer of the laminate 3.

[0030] The main pattern 10 is made of a superconducting material such as niobium (Nb). Note that the material for forming the main pattern 10 is not limited to niobium (Nb). The main pattern 10 forms circuits such as wiring, resonators, capacitors, and ground planes.

[0031] The first conductor pattern 30 and the second conductor pattern 40 form a superconducting quantum interference circuit via a Josephson junction 50. The first conductor pattern 30 and the second conductor pattern 40 are made of a superconducting material such as aluminum (Al). Note that the material for forming the first conductor pattern 30 and the second conductor pattern 40 is not limited to aluminum (Al).

[0032] The first conductor pattern 30 is laminated on the substrate 2 and the main pattern 10. The second conductor pattern 40 is laminated on the substrate 2, the main pattern 10, and the first conductor pattern 30. An oxide film 30a (AlOx: aluminum oxide) is formed between the first conductor pattern 30 and the second conductor pattern 40. The oxide film 30a functions as a tunnel barrier layer of the Josephson junction 50.

[0033] The oxide film 30a is formed on a surface of the first conductor pattern 30 that is not in contact with the substrate 2 or the main pattern 10. The oxide film 30a can be formed, for example, by oxidizing the surface of the first conductor pattern 30 before the second conductor pattern 40 is laminated on the first conductor pattern 30.

[0034] A Josephson junction 50 is formed in the center in the longitudinal direction (X-axis direction) of the connection pattern 20. The Josephson junction 50 is formed by overlapping one of the pair of first conductor patterns 30 (the first conductor pattern 30 arranged on the −X side) and one of the pair of second conductor patterns 40 (the second conductor pattern 40 arranged on the +X side) with an oxide film 30a interposed therebetween.

[0035] The Josephson junction 50 is formed by oblique deposition, as will be described later. In this method, a mask corresponding to the shapes of the first conductor pattern 30 and the second conductor pattern 40 is provided in advance on the substrate 2. Then, thin films of superconducting material (the first conductor pattern 30 and the second conductor pattern 40) are formed twice by changing the deposition direction on the substrate 2.

[0036] 3, oblique deposition is performed from the -X side to the +X side in the X-axis direction at a predetermined angle to the -X side with respect to the direction perpendicular to the surface of the substrate 2, thereby forming a pair of first conductor patterns 30. In the second deposition process, oblique deposition is performed from the +X side to the -X side in the X-axis direction at a predetermined angle to the +X side with respect to the direction perpendicular to the surface of the substrate 2, thereby forming a pair of second conductor patterns 40, as shown by arrow F2 in FIG.

[0037] In the first vapor deposition process, oblique vapor deposition is performed as indicated by arrow F1, so that at the facing boundary line 101 portion of the main pattern 10 located on the -X side, the step of the main pattern 10 casts a shadow, which may result in a step discontinuity 32 in the first conductor pattern 30. On the other hand, at the facing boundary line 101 portion of the main pattern 10 located on the +X side, the first conductor pattern 30 is deposited toward the step of the main pattern 10, so there is little possibility of a step discontinuity 32 occurring. Note that in the second vapor deposition process, oblique vapor deposition is performed in the opposite direction in the X-axis direction to that of the first vapor deposition process, so there is a possibility of a step discontinuity 42 occurring on the +X side.

[0038] 4, the first conductor pattern 30 has a riding portion 33 that rides up from the substrate 2 onto the main pattern 10. The riding portion 33 is formed so as to overlap at least the non-facing boundary line 102. Specifically, the non-facing boundary line 102 overlapped by the riding portion 33 includes a parallel portion 102a that extends parallel to the X-axis direction in a plan view. Since the parallel portion 102a is parallel to the X-axis direction of oblique vapor deposition in a plan view, it is unlikely to be shaded by the main pattern 10, and there is little possibility that a step discontinuity 32 will occur in the first conductor pattern 30.

[0039] In this way, even if a step 32 occurs in the first conductor pattern 30 at the facing boundary line 101 due to the oblique vapor deposition indicated by the symbol F1, the provision of a connection structure via the non-facing boundary line 102 ensures a reliable connection between the main pattern 10 formed on the substrate 2 and the first conductor pattern 30 that runs over the main pattern 10. As a result, the superconducting quantum circuit 1 functions normally, and deviations from the designed characteristics can be suppressed.

[0040] Moreover, the riding-up portion 33 is formed so as to overlap a corner 103 where the facing boundary line 101 and the non-facing boundary line 102 intersect. By depositing the first conductor pattern 30 so as to overlap the corner 103 of the main pattern 10 in this way, the first conductor pattern 30 does not protrude too much from the main pattern 10, and therefore the size of the superconducting quantum circuit 1 in the Y-axis direction can be reduced while providing a connection structure via the non-facing boundary line 102.

[0041] 5 to 7 are process diagrams showing a method for manufacturing a superconducting quantum circuit 1 according to the first embodiment of the present disclosure. Like Fig. 3, Fig. 6 corresponds to the cross section taken along III-III in Fig. 2. Fig. 7 corresponds to the cross section taken along VII-VII in Fig. 2. First, as shown in Fig. 5(a), a substrate 2 is prepared. Next, a first conductor layer 10A (Nb layer) is formed on the surface of the substrate 2, as shown in Fig. 5(b).

[0042] The main pattern 10 is formed by, for example, a combination of optical lithography and reactive ion etching. First, as shown in FIG. 5(c), a pattern corresponding to the main pattern 10 is formed in a resist 200 formed on the first conductor layer 10A by optical lithography. Next, as shown in FIG. 5(d), the main pattern 10 is formed by reactive ion etching. Thereafter, as shown in FIG. 5(e), the unnecessary resist 200 is removed.

[0043] The main pattern 10 may be formed by, for example, sputtering, vapor deposition, or CVD (Chemical Vapor Deposition). Electron beam lithography may be used instead of optical lithography. Wet etching may be used instead of reactive ion etching.

[0044] 6(a), a mask 201 and a mask 202 (resist mask) are formed on the substrate 2. Furthermore, until the mask 201 is removed, the mask 201 is not moved relative to the substrate 2 and is fixed at a predetermined height by the mask 202.

[0045] A pair of openings 201a corresponding to the first conductor pattern 30 and the second conductor pattern 40 are formed in the mask 201 by, for example, electron beam lithography. The pair of openings 201a are formed spaced apart in the X-axis direction. As a result, a bridge portion that forms the first gap 31 and the second gap 41 is formed in the mask 201 between the pair of openings 201a.

[0046] 6(b), the first conductor pattern 30 is formed by obliquely depositing a superconducting material 30A (Al layer) from the direction indicated by the arrow F1. The direction of the first oblique deposition is tilted, for example, by about 20 degrees toward the −X side with respect to the direction perpendicular to the surface of the substrate 2. The direction of oblique deposition can be adjusted by, for example, tilting the substrate 2.

[0047] In this way, the first conductor pattern 30 is formed by oblique deposition through the pair of openings 201a in the mask 201. At this time, the first conductor pattern 30 is shielded by a bridge portion between the pair of openings 201a, thereby forming a first gap portion 31 where the first conductor pattern 30 is not deposited on the substrate 2. After the first conductor pattern 30 is deposited, the surface of the first conductor pattern 30 is oxidized.

[0048] Specifically, the surface of the first conductor pattern 30 is oxidized by introducing oxygen gas into a container in which the substrate 2 is placed. As a result, an oxide film 30a (aluminum oxide) is formed on the surface of the first conductor pattern 30.

[0049] 6(c), the second conductor pattern 40 is formed by obliquely depositing a superconducting material 40A (Al layer) from the direction indicated by the arrow F2. The direction of the second oblique deposition is tilted, for example, by about 20 degrees toward the +X side with respect to the direction perpendicular to the surface of the substrate 2. The direction of oblique deposition may be adjusted, for example, by tilting the substrate 2 or by changing the orientation of the nozzle that ejects the superconducting material 40A.

[0050] In this way, the second conductor pattern 40 is formed by oblique deposition through the pair of openings 201a in the mask 201. At this time, the second conductor pattern 40 is shielded by the bridge portion between the pair of openings 201a, thereby forming a second gap portion 41 where the second conductor pattern 40 is not deposited on the substrate 2 and the first conductor pattern 30.

[0051] In a portion located between the first gap 31 and the second gap 41 in plan view (directly below the bridge portion between the pair of openings 201a), a Josephson junction 50 is formed in which one of the pair of first conductor patterns 30 and one of the pair of second conductor patterns 40 overlap with each other via the oxide film 30a. The first gap 31 and the second gap 41 determine the direction of oblique deposition (the angle with respect to the direction perpendicular to the surface of the substrate 2) so that the area of ​​the Josephson junction 50 is appropriate.

[0052] Finally, as shown in Fig. 6(d), the masks 201 and 202 are removed. This removes the excess superconducting materials 30A and 40A that were stacked on the mask 201. In this manner, the superconducting quantum circuit 1 shown in Figs. 2 to 4 is manufactured. Note that at the tip portions of the pair of first conductor patterns 30 and the pair of second conductor patterns 40 that are formed in an L-shape in plan view, the process proceeds as shown in Figs. 7(a) to 7(d).

[0053] The steps shown in Figures 7(a) to 7(d) correspond to the steps shown in Figures 6(a) to 6(d) described above, and will be simplified to avoid duplication. First, as shown in Figure 7(a), a mask 201 is formed. Next, as shown in Figure 7(b), a first conductor pattern 30 is formed by oblique deposition from the direction indicated by arrow F1. Next, as shown in Figure 7(c), a second conductor pattern 40 is formed by oblique deposition from the direction indicated by arrow F2. Finally, as shown in Figure 7(d), the masks 201 and 202 are removed.

[0054] 2 and 3, the superconducting quantum circuit 1 thus manufactured comprises a substrate 2 and a stack 3 of superconducting materials formed on the substrate 2. The stack 3 comprises a pair of main patterns 10 formed on the substrate 2 and spaced apart in the X-axis direction (first direction), and a connection pattern 20 formed on the substrate 2 and the pair of main patterns 10 and connecting the pair of main patterns 10.

[0055] The connection pattern 20 includes a pair of first conductor patterns 30 that extend in the X-axis direction, have first gaps 31 that separate them in the X-axis direction, and have oxide films 30a formed on their surfaces; a pair of second conductor patterns 40 that extend in the X-axis direction, have second gaps 41 that separate them in the X-axis direction, and are shifted in the X-axis direction so as to straddle the first gaps 31 and overlap the pair of first conductor patterns 30; and a Josephson junction 50 that is located between the first gaps 31 and the second gaps 41 in a planar view, and is formed by one of the pair of first conductor patterns 30 and one of the pair of second conductor patterns 40 overlapping with each other via the oxide film 30a.

[0056] 2, a boundary line 100 between the substrate 2 and the pair of main patterns 10 in a plan view includes a facing boundary line 101 located on the side where the pair of main patterns 10 face each other in the X-axis direction, and a non-facing boundary line 102 other than the facing boundary line 101. The pair of first conductor patterns 30 include riding-up portions 33 that ride up from the substrate 2 onto the pair of main patterns 10. As shown in FIG. 4, the riding-up portions 33 are formed so as to overlap at least the non-facing boundary line 102. This configuration provides a connection structure via the non-facing boundary line 102, thereby ensuring reliable connection between the main pattern 10 formed on the substrate 2 and the first conductor pattern 30 that rides up onto the main pattern 10.

[0057] Furthermore, in the first embodiment, the non-opposing boundary line 102 overlapped by the riding-up portion 33 includes a parallel portion 102a extending parallel to the X-axis direction in a plan view. According to this configuration, the parallel portion 102a is parallel to the X-axis direction of oblique vapor deposition in a plan view, and therefore is unlikely to be shaded by the main pattern 10, reducing the possibility of a step discontinuity 32 occurring in the first conductor pattern 30 at the non-opposing boundary line 102.

[0058] Moreover, in the first embodiment, the riding-up portion 33 is formed so as to overlap the corner 103 where the facing boundary line 101 and the non-facing boundary line 102 intersect. With this configuration, the first conductor pattern 30 does not protrude too much from the main pattern 10, and therefore the size of the superconducting quantum circuit 1 in the Y-axis direction can be reduced while providing a connection structure via the non-facing boundary line 102.

[0059] In the first embodiment, the pair of main patterns 10 are made of a niobium material, and the pair of first conductor patterns 30 are made of an aluminum material. This configuration allows the Nb layer and the Al layer in the superconducting quantum circuit 1 to be reliably connected.

[0060] Furthermore, according to a quantum device including the superconducting quantum circuit 1 of the first embodiment, the superconducting quantum circuit 1 functions normally, and therefore deviations from the design characteristics can be suppressed.

[0061] 5 to 7, the method for manufacturing the superconducting quantum circuit 1 according to the first embodiment includes a stack formation step of forming a stack 3 of superconducting materials on a substrate 2. The stack formation step includes a main pattern 10 formation step (see FIG. 5) of forming a pair of main patterns 10 spaced apart in the X-axis direction on the substrate 2, and a connection pattern formation step (see FIGS. 6 and 7) of forming a connection pattern 20 that connects the pair of main patterns 10 on the substrate 2 and the pair of main patterns 10.

[0062] The connection pattern formation process includes a first conductor pattern formation process (see FIG. 6(b)) in which a pair of first conductor patterns 30 extending in the X-axis direction and having first gaps 31 spaced apart in the X-axis direction are formed by a first oblique vapor deposition from one side in the X-axis direction using a mask 201 having a pair of openings 201a spaced apart in the X-axis direction; an oxide film formation process (see FIG. 6(b)) in which an oxide film 30a is formed on the surfaces of the pair of first conductor patterns 30; and a second oblique vapor deposition from the other side in the X-axis direction using the mask 201. and a second conductor pattern forming process (see FIG. 6(c)) in which a pair of second conductor patterns 40 extending in the X-axis direction and having second gaps 41 spaced apart in the X-axis direction are formed by bonding the second conductor patterns 40 to overlap the pair of first conductor patterns 30, shifted in the X-axis direction so as to straddle the first gaps 31, and a Josephson junction 50 in which one of the pair of first conductor patterns 30 and one of the pair of second conductor patterns 40 overlap with each other, with an oxide film 30a interposed between the first gaps 31 and the second gaps 41 in a plan view.

[0063] The boundary line between the substrate 2 and the pair of main patterns 10 in a planar view includes an opposing boundary line located on the side where the pair of main patterns 10 face each other in the X-axis direction, and a non-opposing boundary line 102 other than the opposing boundary line, and in the first conductor pattern forming process, the pair of first conductor patterns 30 form riding-up portions 33 that ride up from the substrate 2 onto the pair of main patterns 10, and the riding-up portions 33 are formed so as to overlap at least the non-opposing boundary line 102 (see Figure 4).

[0064] According to this configuration, in a plan view, the direction in which a current flows through the connection pattern 20 and the direction in which the first conductor pattern 30 and the second conductor pattern 40 are obliquely evaporated are aligned in the X-axis direction. Therefore, according to the above-described method for manufacturing a superconducting quantum circuit 1, the first conductor pattern 30 and the second conductor pattern 40 can be formed using the same mask 201, the number of manufacturing processes can be reduced compared to a manufacturing method in which the first conductor pattern 30 and the second conductor pattern 40 are obliquely evaporated from a direction different from the X-axis direction, and the size of the superconducting quantum circuit 1 in the Y-axis direction can be reduced.

[0065] (Second embodiment) Next, a second embodiment of the present disclosure will be described. In the following description, the same or equivalent components as those in the above-described embodiment will be denoted by the same reference numerals, and the description thereof will be simplified or omitted.

[0066] Fig. 8 is a plan view of a superconducting quantum circuit 1 according to a second embodiment of the present disclosure. Fig. 9 is an enlarged plan view of a main part of the superconducting quantum circuit 1 according to the second embodiment of the present disclosure. As shown in these figures, the main pattern 10 of the second embodiment has extending portions 11 that extend in a direction other than the X-axis direction in plan view. Also, the riding-up portions 33 of the first conductor pattern 30 of the second embodiment are formed so as to overlap the extending portions 11.

[0067] Specifically, the extension portions 11 are formed at corners 103 on both sides in the Y-axis direction of the opposing sides (opposing boundary line 101 sides) of the pair of main patterns 10. As shown in Fig. 9, the extension portions 11 have a right-angled triangular shape including an inclined portion 102b extending in a direction intersecting the X-axis direction. The inclined portion 102b is part of the non-opposing boundary line 102 and is inclined at an angle θ with respect to a reference line L extending in the X-axis direction in a plan view.

[0068] The angle θ is set in the range of 0° to 179°. Preferably, the angle θ is set in the range of 0° to 90°. More preferably, the angle θ is set in the range of 0° to 45°. Even more preferably, the angle θ is set in the range of more than 0° and less than 45°.

[0069] As described above, in the second embodiment, the non-opposing boundary line 102 overlapped by the riding-up portion 33 includes an inclined portion 102b extending in a direction intersecting the X-axis direction in a plan view. The step surface of the inclined portion 102b is formed in an orientation having an X component that faces the direction indicated by the arrow F1 in a plan view, in which the first conductor pattern 30 is obliquely vapor-deposited, so that the first conductor pattern 30 is reliably deposited on the step surface. This ensures that the main pattern 10 and the first conductor pattern 30 are reliably connected. Furthermore, since the angle θ is greater than 0° compared to when it is 0°, deposition of the step surface of the inclined portion 102b is more reliable.

[0070] Furthermore, in the second embodiment, the pair of main patterns 10 includes extending portions 11 extending in a direction other than the X-axis direction in a plan view, and at least a portion of the non-facing boundary line 102 where the riding-up portion 33 overlaps is formed in the extending portions 11. This configuration makes it easier to form the inclined portions 102b that reliably connect the main pattern 10 and the first conductor pattern 30. Furthermore, by setting the angle θ to 45° or less or smaller than 45°, the extending portions 11 can be made small in size. In particular, the extending portions 11 can be shaped so that the inclined portions 102b are long while maintaining a small size in the Y-axis direction. This allows the step surface on which the first conductor pattern 30 is reliably formed to be long in the inclined portions 102b, thereby improving conductivity.

[0071] (Third embodiment) Next, a third embodiment of the present disclosure will be described. In the following description, the same or equivalent components as those in the above-described embodiment will be denoted by the same reference numerals, and the description thereof will be simplified or omitted.

[0072] Fig. 10 is a plan view of a superconducting quantum circuit 1 according to a third embodiment of the present disclosure. Fig. 11 is an enlarged plan view of a main part of the superconducting quantum circuit 1 according to the third embodiment of the present disclosure. As shown in these figures, the non-facing boundary line 102 overlapped by the riding portion 33 of the third embodiment includes an orthogonal portion 102c extending in a direction (Y-axis direction) orthogonal to the X-axis direction in plan view.

[0073] 11, the orthogonal portion 102c is formed in the extending portion 11 of the main pattern 10. The extending portion 11 of the second embodiment has a rectangular shape extending in the Y-axis direction in a plan view. The extending portion 11 includes the orthogonal portion 102c and the parallel portion 102a.

[0074] As described above, in the third embodiment, the non-facing boundary line 102 overlapped by the riding-up portion 33 includes an orthogonal portion 102c extending in a direction orthogonal to the X-axis direction in plan view. With this configuration, the step surface of the orthogonal portion 102c is formed facing the direction indicated by the arrow F1 in plan view, in which the first conductor pattern 30 is obliquely vapor-deposited, so that the first conductor pattern 30 is reliably deposited on the step surface. This ensures that the main pattern 10 and the first conductor pattern 30 are connected reliably.

[0075] Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and design modifications and the like are also included within the scope of the present disclosure. Furthermore, each embodiment can be appropriately combined with other embodiments.

[0076] Furthermore, some or all of the above-described embodiments can be described as, but are not limited to, the following supplementary notes.

[0077] (Appendix 1) A substrate; a stack of superconducting material formed on the substrate; The laminate is a pair of main patterns formed on the substrate and spaced apart in a first direction; a connection pattern formed on the substrate and the pair of main patterns, and connecting the pair of main patterns; The connection pattern is a pair of first conductor patterns extending in the first direction, having a first gap spaced apart from each other in the first direction, and having an oxide film formed on a surface thereof; a pair of second conductor patterns extending in the first direction, having a second gap spaced apart from each other in the first direction, and overlapping the pair of first conductor patterns while being shifted in the first direction so as to straddle the first gap; a Josephson junction located between the first gap and the second gap in plan view, and formed by one of the pair of first conductor patterns and one of the pair of second conductor patterns overlapping with each other via the oxide film, The boundary line between the substrate and the pair of main patterns in a plan view is an opposing boundary line located on sides where the pair of main patterns face each other in the first direction; a non-opposing boundary line other than the opposing boundary line, the pair of first conductor patterns have extending portions extending from the substrate onto the pair of main patterns, The riding-up portion is formed so as to overlap at least the non-facing boundary line. Superconducting quantum circuits.

[0078] (Appendix 2) The non-opposing boundary line on which the riding-up portion overlaps includes a parallel portion extending parallel to the first direction in a plan view. 1. The superconducting quantum circuit of claim 1.

[0079] (Appendix 3) The non-opposing boundary line on which the riding-up portion overlaps includes an inclined portion extending in a direction intersecting with the first direction in a plan view. 3. The superconducting quantum circuit of claim 1 or 2.

[0080] (Appendix 4) The non-opposing boundary line on which the riding-up portion overlaps includes an orthogonal portion extending in a direction orthogonal to the first direction in a plan view. 4. The superconducting quantum circuit of any one of appendices 1 to 3.

[0081] (Appendix 5) the pair of main patterns include extending portions extending in a direction other than the first direction in a plan view, At least a part of the non-facing boundary line overlapped by the riding-up portion is formed on the extension portion. 5. The superconducting quantum circuit of any one of appendices 1 to 4.

[0082] (Appendix 6) The overhanging portion is formed so as to overlap a corner portion where the opposing boundary line and the non-opposing boundary line intersect. 6. The superconducting quantum circuit of any one of appendices 1 to 5.

[0083] (Appendix 7) the pair of main patterns are formed from a niobium material; 7. The superconducting quantum circuit of any one of appendices 1 to 6.

[0084] (Appendix 8) the pair of first conductor patterns are made of an aluminum material; 8. The superconducting quantum circuit of any one of appendices 1 to 7.

[0085] (Appendix 9) A quantum device comprising the superconducting quantum circuit of any one of appendices 1 to 8.

[0086] (Appendix 10) a laminate formation step of forming a laminate of superconducting materials on a substrate, The laminate forming step includes: a main pattern forming step of forming a pair of main patterns spaced apart in a first direction on the substrate; a connection pattern forming step of forming a connection pattern on the substrate and the pair of main patterns to connect the pair of main patterns, The connection pattern forming step includes: a first conductor pattern forming step of forming a pair of first conductor patterns extending in the first direction and having a first gap spaced apart in the first direction by a first oblique deposition from one side in the first direction through a mask having a pair of openings spaced apart in the first direction; an oxide film forming step of forming an oxide film on surfaces of the pair of first conductor patterns; a second conductor pattern forming step of forming, by a second oblique deposition from the other side of the first direction via the mask, a pair of second conductor patterns extending in the first direction and having a second gap spaced apart in the first direction, overlapping the pair of first conductor patterns while being shifted in the first direction so as to straddle the first gap, and forming a Josephson junction where one of the pair of first conductor patterns and one of the pair of second conductor patterns overlap with each other via the oxide film between the first gap and the second gap in plan view, The boundary line between the substrate and the pair of main patterns in a plan view is an opposing boundary line located on sides where the pair of main patterns face each other in the first direction; a non-opposing boundary line other than the opposing boundary line, In the first conductor pattern forming step, the pair of first conductor patterns form overhanging portions that extend from the substrate onto the pair of main patterns, and the overhanging portions are formed so as to overlap at least the non-facing boundary line. A method for manufacturing superconducting quantum circuits. [Explanation of symbols]

[0087] 1 Superconducting quantum circuits 2 boards 3 Laminate 10 Main Pattern 10A First conductor layer 11 Extension 20 Connection Patterns 30 First conductor pattern 30a oxide film 30A superconducting material 31 First gap 32 Step break 33 Riding section 40 Second conductor pattern 40A superconducting material 41 Second gap 42 Step break 50 Josephson junction 100 Borderline 101 Opposite boundary line 102 Non-opposing boundary line 102a Parallel part 102b Slope 102c Orthogonal section 103 Corner

Claims

1. A substrate; a stack of superconducting material formed on the substrate; The laminate is a pair of main patterns formed on the substrate and spaced apart in a first direction; a connection pattern formed on the substrate and the pair of main patterns, and connecting the pair of main patterns; The connection pattern is a pair of first conductor patterns extending in the first direction, having a first gap spaced apart from each other in the first direction, and having an oxide film formed on a surface thereof; a pair of second conductor patterns extending in the first direction, having a second gap spaced apart from each other in the first direction, and overlapping the pair of first conductor patterns while being shifted in the first direction so as to straddle the first gap; a Josephson junction located between the first gap and the second gap in a plan view, and formed by one of the pair of first conductor patterns and one of the pair of second conductor patterns overlapping with each other via the oxide film, The boundary line between the substrate and the pair of main patterns in a plan view is an opposing boundary line located on sides where the pair of main patterns face each other in the first direction; a non-opposing boundary line other than the opposing boundary line, the pair of first conductor patterns each include a rising portion rising from the substrate onto the pair of main patterns, The riding-up portion is formed so as to overlap at least the non-facing boundary line. Superconducting quantum circuits.

2. The non-opposing boundary line on which the riding-up portion overlaps includes a parallel portion extending parallel to the first direction in a plan view.

2. The superconducting quantum circuit of claim 1.

3. The non-opposing boundary line on which the riding-up portion overlaps includes an inclined portion extending in a direction intersecting with the first direction in a plan view.

3. The superconducting quantum circuit according to claim 1 or 2.

4. The non-opposing boundary line on which the riding-on portion overlaps includes an orthogonal portion extending in a direction orthogonal to the first direction in a plan view.

3. The superconducting quantum circuit according to claim 1 or 2.

5. the pair of main patterns include extending portions extending in a direction other than the first direction in a plan view, At least a part of the non-facing boundary line overlapped by the riding-up portion is formed on the extension portion.

3. The superconducting quantum circuit according to claim 1 or 2.

6. The overhanging portion is formed so as to overlap a corner portion where the opposing boundary line and the non-opposing boundary line intersect.

3. The superconducting quantum circuit according to claim 1 or 2.

7. the pair of main patterns are formed from a niobium material; 3. The superconducting quantum circuit according to claim 1 or 2.

8. the pair of first conductor patterns are made of an aluminum material; 3. The superconducting quantum circuit according to claim 1 or 2.

9. A quantum device comprising the superconducting quantum circuit according to claim 1 or 2.

10. a laminate formation step of forming a laminate of superconducting materials on a substrate, The laminate forming step includes: a main pattern forming step of forming a pair of main patterns spaced apart in a first direction on the substrate; a connection pattern forming step of forming a connection pattern on the substrate and the pair of main patterns to connect the pair of main patterns, The connection pattern forming step includes: a first conductor pattern forming step of forming a pair of first conductor patterns extending in the first direction and having a first gap spaced apart in the first direction by a first oblique deposition from one side in the first direction through a mask having a pair of openings spaced apart in the first direction; an oxide film forming step of forming an oxide film on surfaces of the pair of first conductor patterns; a second conductor pattern forming step of forming, by a second oblique deposition from the other side in the first direction via the mask, a pair of second conductor patterns extending in the first direction and having a second gap spaced apart in the first direction, overlapping the pair of first conductor patterns while being shifted in the first direction so as to straddle the first gap, and forming a Josephson junction where one of the pair of first conductor patterns and one of the pair of second conductor patterns overlap with each other via the oxide film between the first gap and the second gap in plan view, The boundary line between the substrate and the pair of main patterns in a plan view is an opposing boundary line located on sides where the pair of main patterns face each other in the first direction; a non-opposing boundary line other than the opposing boundary line, In the first conductor pattern forming step, the pair of first conductor patterns form overhanging portions that extend from the substrate onto the pair of main patterns, and the overhanging portions are formed so as to overlap at least the non-facing boundary line. A method for manufacturing superconducting quantum circuits.

Images