Method for manufacturing a Josephson junction and method for manufacturing a qubit device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- FUJITSU LTD
- Filing Date
- 2022-09-28
- Publication Date
- 2026-07-30
Smart Images
Figure 0007897524000001 
Figure 0007897524000002 
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Abstract
Description
Technical Field
[0001] The present invention relates to a method for manufacturing a Josephson junction element and a method for manufacturing a quantum bit device.
Background Art
[0002] The development of superconducting quantum computers equipped with quantum bit devices is underway. As a quantum bit device, a configuration including a quantum bit in which a Josephson junction element and a capacitor are connected in parallel is known. The Josephson junction element has a structure in which an insulating film is sandwiched between two superconducting films. As a method for manufacturing a Josephson junction element, it is known to form a superconducting film by oblique evaporation using a mask layer and then remove the mask layer by lift-off (for example, Patent Documents 1 and 2). In addition, in order to shorten the processing time of lift-off, it is known to use a mask layer provided with an opening for the inflow of a stripping liquid used in lift-off in addition to an opening for forming a target pattern (for example, Patent Document 3). Further, in a field-effect transistor, it is known to perform oblique evaporation using a mask layer having openings of different sizes as a mask so that a gate electrode is formed only in the large opening (for example, Patent Document 4).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Patent Document 2
Patent Document 3
Patent Document 4
Summary of the Invention
Problems to be Solved by the Invention
[0004] Josephson junctions used in qubits are small in plan view. Therefore, when forming a superconducting film for a Josephson junction by depositing a film from an oblique direction using a mask layer as a mask, the openings made in the mask layer to form the superconducting film become small in plan view. Consequently, when removing the mask layer by lift-off, the pathways through which the stripping solution can penetrate the mask layer are limited, resulting in a longer stripping time for the mask layer.
[0005] Patent Document 3 describes a method for shortening the lift-off processing time by providing an inlet for introducing a stripping solution in addition to the opening for forming the target pattern in the mask layer. However, since an unwanted metal film is formed in the area where the inlet is provided, the location of the inlet is limited. Therefore, there is still room for improvement in terms of shortening the stripping time of the mask layer.
[0006] One aspect of this approach is to shorten the mask layer peeling time. [Means for solving the problem]
[0007] In one embodiment, the process involves forming a mask layer on a substrate having a first mask pattern including a first opening extending in a first direction and a second opening extending in a second direction intersecting the first direction, and a second mask pattern including a third opening shorter than the second opening in the first direction and shorter than the first opening in the second direction; and forming a first superconducting film on the substrate in the first mask pattern by first film deposition from obliquely above the substrate using the mask layer as a mask. A method for manufacturing a Josephson junction element, comprising the steps of: forming an insulating film on the surface of the first superconducting film; forming a second superconducting film having a region that overlaps with the first superconducting film in the first mask pattern via the insulating film by second film deposition from obliquely above the substrate using the mask layer as a mask; and removing the mask layer by lift-off. In one embodiment, a first mask pattern is provided on a substrate, comprising: a first mask pattern having an upper layer and a lower layer, the upper layer having a first opening extending in a first direction and a second opening extending in a second direction intersecting the first direction, and a first void formed in the lower layer below the first and second openings and larger in plan view than the first and second openings; a third opening formed in the upper layer that is shorter in the first direction than the second opening and shorter in the second direction than the first opening; and a second void formed in the lower layer below the third opening and larger in plan view than the third opening. A method for manufacturing a Josephson junction element, comprising the steps of: forming a mask layer having a second mask pattern; forming a first superconducting film on the substrate in the first mask pattern by first film deposition from obliquely above the substrate using the mask layer as a mask; forming an insulating film on the surface of the first superconducting film; forming a second superconducting film in the first mask pattern having a region that overlaps with the first superconducting film via the insulating film by second film deposition from obliquely above the substrate using the mask layer as a mask; and removing the mask layer by lift-off.
[0008] In one embodiment, the method for manufacturing a qubit device comprises the steps of: forming a Josephson junction element; forming a capacitor connected in parallel to the Josephson junction element; and forming a resonator and a filter connected to a qubit including the Josephson junction element and the capacitor, wherein the step of forming the Josephson junction element comprises: forming a mask layer on a substrate having a first mask pattern including a first opening extending in a first direction and a second opening extending in a second direction intersecting the first direction, and a second mask pattern including a third opening shorter than the second opening in the first direction and shorter than the first opening in the second direction; forming a first superconducting film on the substrate in the first mask pattern by first film deposition from obliquely above the substrate using the mask layer as a mask; forming an insulating film on the surface of the first superconducting film; forming a second superconducting film in the first mask pattern having a region overlapping the first superconducting film via the insulating film in the first mask pattern by second film deposition from obliquely above the substrate using the mask layer as a mask; and removing the mask layer by lift-off. [Effects of the Invention]
[0009] One aspect of this is that the mask layer peeling time can be shortened. [Brief explanation of the drawing]
[0010] [Figure 1] Figures 1(a) to 1(c) are diagrams (part 1) showing a method for manufacturing a Josephson junction element according to Example 1. [Figure 2] Figures 2(a) to 2(c) are diagrams (part 2) showing the method for manufacturing a Josephson junction element according to Example 1. [Figure 3] Figures 3(a) to 3(c) are diagrams (part 3) showing the method for manufacturing a Josephson junction element according to Example 1. [Figure 4] Figures 4(a) to 4(c) are diagrams (part 4) showing the method for manufacturing a Josephson junction element according to Example 1. [Figure 5] Figs. 5(a) to 5(c) are diagrams (Part 5) showing a method for manufacturing a Josephson junction device according to Example 1. [Figure 6] Figs. 6(a) to 6(d) are diagrams (Part 1) showing a method for manufacturing a Josephson junction device according to a comparative example. [Figure 7] Figs. 7(a) to 7(d) are diagrams (Part 2) showing a method for manufacturing a Josephson junction device according to a comparative example. [Figure 8] Fig. 8(a) is a plan view of a model used for simulation, and Fig. 8(b) is a cross-sectional view taken along line A-A of Fig. 8(a). [Figure 9] Fig. 9 is a diagram showing simulation results. [Figure 10] Fig. 10(a) is a cross-sectional view of a portion corresponding to between C-C of Fig. 2(a), and Fig. 10(b) is a cross-sectional view of a portion corresponding to between C-C of Fig. 4(a). [Figure 11] Fig. 11(a) is an enlarged plan view of the vicinity of the mask pattern of Fig. 4(a), Fig. 11(b) is a cross-sectional view taken along line A-A of Fig. 11(a), and Fig. 11(c) is a cross-sectional view taken along line B-B of Fig. 11(a). [Figure 12] Figs. 12(a) and 12(b) are diagrams (Part 1) showing a method for manufacturing a Josephson junction device according to Example 2. [Figure 13] Figs. 13(a) and 13(b) are diagrams (Part 2) showing a method for manufacturing a Josephson junction device according to Example 2. [Figure 14] Figs. 14(a) and 14(b) are diagrams (Part 3) showing a method for manufacturing a Josephson junction device according to Example 2. [Figure 15] Figs. 15(a) and 15(b) are diagrams (Part 4) showing a method for manufacturing a Josephson junction device according to Example 2. [Figure 16] Figs. 16(a) and 16(b) are diagrams (Part 5) showing a method for manufacturing a Josephson junction device according to Example 2. [Figure 17]FIG. 17(a) is an enlarged plan view of the vicinity of the mask pattern in FIG. 15(a), and FIG. 17(b) is a sectional view taken along the line A-A in FIG. 17(a). [Figure 18] FIG. 18(a) is a plan view of the quantum bit device according to Example 3, and FIG. 18(b) is an enlarged view of the quantum bit in FIG. 18(a). [Figure 19] FIGS. 19(a) to 19(d) are sectional views (Part 1) showing the manufacturing method of the quantum bit device according to Example 3. [Figure 20] FIGS. 20(a) to 20(c) are sectional views (Part 2) showing the manufacturing method of the quantum bit device according to Example 3. [Figure 21] FIGS. 21(a) to 21(c) are sectional views (Part 3) showing the manufacturing method of the quantum bit device according to Example 3.
BEST MODE FOR CARRYING OUT THE INVENTION
[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings.
EXAMPLE
[0012] In Example 1, a method for manufacturing a Josephson junction element called the Manhattan type will be described. FIGS. 1(a) to 5(c) are diagrams showing the manufacturing method of the Josephson junction element according to Example 1. FIGS. 1(a), 2(a), 3(a), 4(a), and 5(a) are plan views showing the manufacturing method of the Josephson junction element according to Example 1. FIGS. 1(b), 2(b), 3(b), 4(b), and 5(b) are sectional views taken along the line A-A in FIGS. 1(a), 2(a), 3(a), 4(a), and 5(a). FIGS. 1(c), 2(c), 3(c), 4(c), and 5(c) are sectional views taken along the line B-B in FIGS. 1(a), 2(a), 3(a), 4(a), and 5(a). In FIGS. 2(a), 3(a), and 4(a), for clarity of the figure, hatching is added to the superconducting film 14, insulating film 16, and superconducting film 18 formed in the gap 26 (the same applies to the following similar figures).
[0013] As shown in Figures 1(a) to 1(c), a mask layer 12 is formed on the substrate 10. The substrate 10 is, for example, a high-resistance silicon substrate. The mask layer 12 is formed of, for example, photoresist and has an upper layer 13a and a lower layer 13b. The thickness of the upper layer 13a is, for example, thinner than the thickness of the lower layer 13b. For example, the thickness of the upper layer 13a is 200 nm and the thickness of the lower layer 13b is 800 nm. The mask layer 12 has a mask pattern 20 including an opening 22, an opening 24 and a void 26, and a mask pattern 30 including an opening 32 and a void 36.
[0014] In the mask pattern 20, the opening 22 extends in the X-axis direction, and the opening 24 intersects (e.g., perpendicular to) the opening 22 and extends in the Y-axis direction, both formed in the upper layer 13a. Thus, the mask pattern 20 has a cross-shaped opening formed by the openings 22 and 24 in the upper layer 13a. The width of the opening 22 (length in the Y-axis direction) and the width of the opening 24 (length in the X-axis direction) are, for example, approximately the same. The widths of the openings 22 and 24 are, for example, 100 nm to 300 nm, and 200 nm as an example. The length of the opening 22 (length in the X-axis direction) and the length of the opening 24 (length in the Y-axis direction) are, for example, approximately the same, and 1 μm or more. The void 26 is formed in the lower layer 13b. The void 26 is located below the openings 22 and 24 and has a larger shape than the openings 22 and 24 in a plan view. For example, the mask layer 12 is formed using a photoresist in which the lower layer 13b is more sensitive than the upper layer 13a to exposure (e.g., electron beam exposure) for forming the openings 22, 24 and voids 26. As a result, when openings 22, 24 are formed in the upper layer 13a, voids 26 are formed in the lower layer 13b with a shape that is larger than the openings 22, 24.
[0015] In the mask pattern 30, the opening 32 is formed in the upper layer 13a with a smaller shape in plan view than the region 40 where the openings 22 and 24 of the mask pattern 20 intersect. That is, the length of the opening 32 in the X-axis direction is shorter than the length of the opening 24 in the X-axis direction, and the length of the opening 32 in the Y-axis direction is shorter than the length of the opening 22 in the Y-axis direction. The opening 32 is, for example, rectangular in plan view, with lengths of 150 nm in the X-axis direction and 150 nm in the Y-axis direction. The opening 32 may also have other shapes such as circular or elliptical in plan view. The void 36 is formed in the lower layer 13b. The void 36 is located below the opening 32 and has a larger shape in plan view than the opening 32. By using a photoresist in the lower layer 13b that is more sensitive to exposure than the upper layer 13a, when the opening 32 is formed in the upper layer 13a, a void 36 is formed in the lower layer 13b with a shape similar to a larger version of the opening 32. Multiple mask patterns 30 are formed around the mask pattern 20, enclosing it. The multiple mask patterns 30 are arranged such that the spacing between adjacent mask patterns 30 is approximately constant in the X-axis and Y-axis directions, without passing through the mask pattern 20, for example, in a grid pattern. The multiple mask patterns 30 may also be arranged in a staggered pattern.
[0016] As shown in Figures 2(a) to 2(c), a mask layer 12 is used as a mask, and a superconducting film 14 is formed on the substrate 10 by deposition from an oblique upward direction in the -X direction, as indicated by the arrow 50. For example, the superconducting film 14 is formed by oblique vacuum deposition. The incident angle θ1 of the deposition material with respect to the normal 11 of the substrate 10 is, for example, 30° to 60°, and 45° as an example. The superconducting film 14 is, for example, an aluminum (Al) film. Because the superconducting film 14 is formed by deposition from an oblique upward direction in the -X direction, the formation of a superconducting film 14 extending in the Y-axis direction within the void 26 is suppressed by making the width of the opening 24 an appropriate size. A superconducting film 14 extending in the X-axis direction is formed within the void 26. The thickness of the superconducting film 14 is, for example, 10 nm to 100 nm, and 30 nm as an example.
[0017] Here, we will explain how the formation of a superconducting film 14 extending in the Y-axis direction within the void 26 is suppressed. Let θ1 be the angle of incidence of the film deposition material with respect to the normal 11 of the substrate 10, T be the thickness of the upper layer 13a of the mask layer 12, and W1 be the width of the opening 24. In this case, the width of the opening 24 is set such that W1 ≤ T × tanθ1. As a result, it becomes difficult for the film deposition material to be incident into the void 26 through the opening 24, and the formation of a superconducting film 14 extending in the Y-axis direction within the void 26 is suppressed.
[0018] Since the superconducting film 14 is formed by deposition from diagonally above in the -X direction, the superconducting film 14 is formed offset in the +X direction relative to the opening 22. Because the length of the opening 32 in the mask pattern 30 in the X direction is shorter than the width W1 of the opening 24, the formation of the superconducting film 14 within the void 36 is suppressed.
[0019] As shown in Figures 3(a) to 3(c), oxygen is introduced into the chamber while maintaining the vacuum state that was in place when the superconducting film 14 was formed, thereby oxidizing the surface of the superconducting film 14 and forming an insulating film 16 on the surface of the superconducting film 14.
[0020] As shown in Figures 4(a) to 4(c), the mask layer 12 is used as a mask, and a superconducting film 18 is formed on the substrate 10 by deposition from an oblique upward direction in the +Y direction, as indicated by arrow 52. For example, the superconducting film 18 is formed by oblique vacuum deposition. The incident angle θ2 of the deposition material with respect to the normal 11 of the substrate 10 is, for example, 30° to 60°, and 45° as an example. The superconducting film 18 is, for example, an aluminum (Al) film. Since the superconducting film 18 is formed by deposition from an oblique upward direction in the +Y direction, the formation of a superconducting film 18 extending in the X direction within the gap 26 is suppressed by making the width of the opening 22 an appropriate size. A superconducting film 18 extending in the Y direction is formed within the gap 26. That is, similar to the case of the superconducting film 14, when the incident angle of the deposition material with respect to the normal 11 of the substrate 10 is θ2, the thickness of the upper layer 13a of the mask layer 12 is T, and the width of the opening 22 is W2, the relationship W2 ≤ T × tanθ2 is satisfied. This makes it difficult for the film-forming material to enter the void 26 through the opening 22, thereby suppressing the formation of a superconducting film 18 extending in the X-axis direction within the void 26. The thickness of the superconducting film 18 is, for example, about 10 nm to 100 nm, and 40 nm as one example.
[0021] As a superconducting film 18 extending in the Y-axis direction is formed within the gap 26, a region 42 is formed where the superconducting film 14 extending in the X-axis direction and the superconducting film 18 extending in the Y-axis direction overlap via the insulating film 16. Since the superconducting film 18 is formed by deposition from obliquely above in the +Y direction, the superconducting film 18 is formed offset in the -Y direction relative to the opening 24. In the mask pattern 30, the length of the opening 32 in the Y-axis direction is shorter than the width W2 of the opening 22, thus suppressing the formation of the superconducting film 18 within the gap 36.
[0022] . As shown in Figures 5(a) to 5(c), the mask layer 12, the superconducting film 14, the insulating film 16, and the superconducting film 18 formed on the mask layer 12 are removed by the lift-off method. The mask layer 12 has openings 22 and 24 in the mask pattern 20 and an opening 32 in the mask pattern 30. Therefore, the stripping solution used in the lift-off method penetrates the mask layer 12 not only through openings 22 and 24 but also through opening 32. The region where the superconducting film 14 extending in the X-axis direction and the superconducting film 18 extending in the Y-axis direction overlap via the insulating film 16 becomes a Josephson junction 46, and a Josephson junction element 100 is formed on the substrate 10. The insulating film 16 has a thickness such that the tunnel effect is obtained at the temperature at which superconductivity occurs.
[0023] [Comparative Example] Figures 6(a) to 7(d) show a method for manufacturing a Josephson junction element according to a comparative example. Figures 6(a), 6(c), 7(a), and 7(c) are plan views showing a method for manufacturing a Josephson junction element according to a comparative example. Figures 6(b), 6(d), 7(b), and 7(d) are cross-sectional views AA of Figures 6(a), 6(c), 7(a), and 7(c). As shown in Figures 6(a) and 6(b), a mask layer 112 is formed on the substrate 10. A mask pattern 20 is formed on the mask layer 112, but a mask pattern 30 is not formed.
[0024] As shown in Figures 6(c) and 6(d), a mask layer 112 is used as a mask, and a superconducting film 14 is formed on the substrate 10 by deposition from an oblique upward direction in the -X direction, as indicated by the arrow 50. Subsequently, while maintaining the vacuum state at which the superconducting film 14 was formed, oxygen is introduced into the chamber to oxidize the surface of the superconducting film 14, thereby forming an insulating film 16 on the surface of the superconducting film 14.
[0025] As shown in Figures 7(a) and 7(b), the mask layer 112 is used as a mask, and the superconducting film 18 is formed on the substrate 10 by deposition from diagonally above in the +Y direction, as indicated by the arrow 52. This creates a region 42 where the superconducting film 14 extending in the X direction and the superconducting film 18 extending in the Y direction overlap via the insulating film 16.
[0026] As shown in Figures 7(c) and 7(d), the mask layer 112 and the superconducting film 14, insulating film 16, and superconducting film 18 formed on the mask layer 112 are removed by the lift-off method. Since no mask pattern 30 is formed on the mask layer 112, the stripping solution used in the lift-off method penetrates only through the openings 22 and 24 in the mask pattern 20. The region where the superconducting film 14 extending in the X-axis direction and the superconducting film 18 extending in the Y-axis direction overlap via the insulating film 16 becomes a Josephson junction 46, and a Josephson junction element 100 is formed on the substrate 10.
[0027] An example of manufacturing a Josephson junction element 100 according to a comparative example is shown. The thickness of the upper layer 13a of the mask layer 112 was 300 nm, and the thickness of the lower layer 13b was 800 nm. The widths of the openings 22 and 24 formed in the mask layer 112 were 200 nm. The superconducting films 14 and 18 were formed by oblique vacuum deposition with an incidence angle of 40° of the deposition material relative to the normal of the substrate 10, and the thickness was 40 nm. The mask layer 112 was removed by lift-off using a stripping solution while heating to 80°C. At this time, the peeling time of the mask layer 112 by lift-off was 120 minutes. Thus, in the comparative example, the lift-off processing time was long. A long lift-off processing time increases manufacturing costs. In addition, there are concerns that the Josephson junction element may be adversely affected by being immersed in the stripping solution for a long time.
[0028] On the other hand, in Example 1, the stripping solution used for lift-off penetrates the mask layer 12 not only through the openings 22 and 24 of the mask pattern 20 but also through the opening 32 of the mask pattern 30. Therefore, in Example 1, the lift-off processing time is shorter compared to the comparative example, and the increase in manufacturing costs can be suppressed.
[0029] [simulation] A simulation was conducted to investigate the correlation between the spacing of the openings 32 in the mask pattern 30, the exposure time of the mask layer 12, and the peeling time due to lift-off of the mask layer 12. Figure 8(a) is a plan view of the model used in the simulation, and Figure 8(b) is a cross-sectional view AA of Figure 8(a). In Figure 8(a), for clarity, the voids 26 and 36 are omitted from the illustration, and the insulating film 16 and superconducting film 18 formed within the void 26 are hatched.
[0030] As shown in Figures 8(a) and 8(b), the model used in the simulation assumed that a metal film 58, which is a titanium nitride film, was provided between the substrate 10 and the mask layer 12. The mask layer 12 was configured to have a mask pattern 20 including openings 22, 24 and voids 26, and a plurality of mask patterns 30 provided around the mask pattern 20, which include square-shaped openings 32 and voids 36 in a plan view. The openings 32 in the plurality of mask patterns 30 were assumed to be arranged in a grid pattern. The thickness T1 of the upper layer 13a of the mask layer 12 was set to 200 nm, and the thickness T2 of the lower layer 13b was set to 800 nm. The width W1 of the opening 22 and the width W2 of the opening 24 in the mask pattern 20 were set to 250 nm, and the length L1 of the opening 22 and the length L2 of the opening 24 were set to 2500 nm. The width W3 of the opening 32 in the mask pattern 30 was set to 100 nm. In this case, the exposure time required to form the mask patterns 20 and 30 on the mask layer 12, and the peeling time required to remove the mask layer 12 by lift-off were simulated when the spacing H between adjacent openings 32 was changed.
[0031] Figure 9 shows the simulation results. The horizontal axis in Figure 9 represents the spacing H [μm] between adjacent openings 32. The left vertical axis represents the peeling time [min] required to remove the mask layer 12, with the peeling time when the spacing H of the openings 32 is 1 μm being used as the reference. The right vertical axis represents the exposure time [h] required to form the mask patterns 20 and 30 on the mask layer 12, with the exposure time when the spacing H of the openings 32 is 3800 μm being used as the reference.
[0032] As shown in Figure 9, the peeling time of the mask layer 12 was approximately 120 mins when the spacing H of the openings 32 was 3800 μm. As the spacing H of the openings 32 decreased and the number of openings 32 increased, the peeling time of the mask layer 12 decreased. For example, when the spacing H of the openings 32 was 800 μm, the peeling time of the mask layer 12 was approximately 25 mins, which was about 1 / 5 of the time when the spacing H of the openings 32 was 3800 μm. When the spacing H of the openings 32 was 400 μm, the peeling time of the mask layer 12 was approximately 12 mins, which was about 1 / 10 of the time when the spacing H of the openings 32 was 3800 μm. When the spacing H of the openings 32 was 250 μm, the peeling time of the mask layer 12 was approximately 8 mins, which was about 1 / 15 of the time when the spacing H of the openings 32 was 3800 μm. This is because the smaller the spacing H between the apertures 32, the more the stripping solution used in lift-off penetrates into the apertures 32, making it easier to remove the mask layer 12. On the other hand, as the spacing H between the apertures 32 decreases and the number of apertures 32 increases, the exposure time in electron beam lithography increases. Thus, there is a trade-off relationship between the spacing H between the apertures 32 and the stripping time and exposure time. However, it can be seen that by setting the spacing H between the apertures 32 to an appropriate size (for example, between 100 μm and 1000 μm), the stripping time can be shortened while suppressing the lengthening of the exposure time.
[0033] As described above, according to Example 1, a mask layer 12 having a mask pattern 20 (first mask pattern) and a mask pattern 30 (second mask pattern) is formed on the substrate 10, as shown in Figures 1(a) to 1(c). The mask pattern 20 includes an opening 22 (first opening) extending in the X-axis direction and an opening 24 (second opening) extending in the Y-axis direction. The mask pattern 30 includes an opening 32 that is shorter than the opening 22 in the Y-axis direction and shorter than the opening 24 in the X-axis direction. As shown in Figures 2(a) to 2(c), a superconducting film 14 is formed on the substrate 10 in the mask pattern 20 by using the mask layer 12 as a mask and depositing the film from an oblique upward direction in the -X direction (first oblique upward direction) (first film deposit). As shown in Figures 3(a) to 3(c), an insulating film 16 is formed on the surface of the superconducting film 14. As shown in Figures 4(a) to 4(c), the mask layer 12 is used as a mask, and the superconducting film 18 is formed on the mask pattern 20 by deposition (second deposition) from an oblique upward direction in the +Y direction (second oblique upward direction). The superconducting film 18 is formed having a region 42 that overlaps with the superconducting film 14 via the insulating film 16. As shown in Figures 5(a) to 5(c), the mask layer 12 is removed by lift-off. In this way, since the opening 32 is shorter than the opening 22 in the Y-axis direction and shorter than the opening 24 in the X-axis direction, the formation of superconducting films 14 and 18 on the substrate 10 in the mask pattern 30 is suppressed. Therefore, the degree of freedom in the formation position of the mask pattern 30 is increased, and it becomes possible to form the mask pattern 30 at a desired location. Since the peeling solution during lift-off penetrates the mask layer 12 not only from the openings 22 and 24 of the mask pattern 20 but also from the opening 32 of the mask pattern 30, the peeling time of the mask layer 12 can be shortened.
[0034] Furthermore, in Example 1, as shown in Figures 2(a) to 2(c), the superconducting film 14 is not formed on the substrate 10 in the mask pattern 30. As shown in Figures 4(a) to 4(c), the superconducting film 18 is not formed on the substrate 10 in the mask pattern 30. This increases the degree of freedom in the formation position of the mask pattern 30.
[0035] Furthermore, in Example 1, as shown in Figure 1(a), multiple mask patterns 30 are provided around the mask pattern 20. Since the formation of superconducting films 14 and 18 on the substrate 10 is suppressed in the mask patterns 30, multiple mask patterns 30 can be provided around the mask pattern 20. As a result, the peeling solution during lift-off penetrates into the mask layer 12 through the openings 32 of the multiple mask patterns 30, and the peeling time of the mask layer 12 can be shortened.
[0036] Furthermore, in Example 1, as shown in Figure 1(a), the multiple mask patterns 30 are arranged in a line such that the spacing between adjacent mask patterns 30 is constant in the X-axis and Y-axis directions, without passing through the mask pattern 20. This allows the peeling liquid during lift-off to penetrate a wide area of the mask layer 12 through the opening 32 without being concentrated on a part of the mask layer 12, thus shortening the peeling time of the mask layer 12. The multiple mask patterns 30 may be arranged in a grid pattern, or in a staggered pattern, for example.
[0037] Figure 10(a) is a cross-sectional view of the area corresponding to the CC in Figure 2(a), and Figure 10(b) is a cross-sectional view of the area corresponding to the CC in Figure 4(a). As shown in Figure 10(a), in the formation of the superconducting film 14, the angle of incidence of the film deposition material with respect to the normal 11 of the substrate 10 when deposition is made from obliquely above in the -X direction is θ1. The thickness of the upper layer 13a of the mask layer 12 is T. The length of the opening 32 in the X-axis direction, which is the direction corresponding to the obliquely above in the -X direction, is L1. In this case, it is preferable that L1 ≤ T × tanθ1 is satisfied. This suppresses the formation of the superconducting film 14 on the substrate 10 in the mask pattern 30. From the viewpoint of suppressing the formation of the superconducting film 14 on the substrate 10 in the mask pattern 30, it is more preferable that L1 ≤ 0.9 × (T × tanθ1) is satisfied, and even more preferable that L1 ≤ 0.8 × (T × tanθ1) is satisfied.
[0038] As shown in Figure 10(b), in the formation of the superconducting film 18, the angle of incidence of the film deposition material with respect to the normal 11 of the substrate 10 when deposition is made from an oblique upward direction in the +Y direction is θ2. The thickness of the upper layer 13a of the mask layer 12 is T. The length of the opening 32 in the Y-axis direction, which corresponds to the oblique upward direction in the +Y direction, is L2. In this case, it is preferable that L2 ≤ T × tanθ2 is satisfied. This suppresses the formation of the superconducting film 18 on the substrate 10 in the mask pattern 30. From the viewpoint of suppressing the formation of the superconducting film 18 on the substrate 10 in the mask pattern 30, it is more preferable that L2 ≤ 0.9 × (T × tanθ2) is satisfied, and even more preferable that L2 ≤ 0.8 × (T × tanθ2) is satisfied.
[0039] Figure 11(a) is a magnified plan view of the vicinity of the mask pattern 30 in Figure 4(a), Figure 11(b) is a cross-sectional view of AA in Figure 11(a), and Figure 11(c) is a cross-sectional view of BB in Figure 11(a). Note that in Figures 11(a) to 11(c), the insulating film 16 is very thin compared to the superconducting films 14 and 18, so it is not shown here. As shown in Figures 11(a) to 11(c), the superconducting film 14 is formed by deposition from an oblique upward direction in the -X direction, and the superconducting film 18 is formed by deposition from an oblique upward direction in the +Y direction, so the superconducting films 14 and 18 are formed on the side surface of the opening 32. For this reason, the length L1 in the X-axis direction of the opening 32 is made greater than the thickness of the superconducting film 14, and the length L2 in the Y-axis direction of the opening 32 is made greater than the thickness of the superconducting film 18, so that the peeling liquid during lift-off can penetrate into the mask layer 12 from the opening 32. From the perspective of allowing the stripping solution to penetrate the mask layer 12 through the opening 32, the length L1 of the opening 32 in the X-axis direction is preferably 1.5 times or more the thickness of the superconducting film 14, more preferably 1.8 times or more, and even more preferably 2.0 times or more. Similarly, the length L2 of the opening 32 in the Y-axis direction is preferably 1.5 times or more the thickness of the superconducting film 18, more preferably 1.8 times or more, and even more preferably 2.0 times or more.
[0040] In Example 1, as shown in Figure 1(a), a mask layer 12 is formed having a mask pattern 20 in which an opening 22 extending in the X-axis direction and an opening 24 extending in the Y-axis direction intersect. As shown in Figure 2(a), a superconducting film 14 is formed on the substrate 10 in the mask pattern 20 by deposition from an oblique upward direction in the -X direction. As shown in Figure 4(a), a superconducting film 18 is formed on the substrate 10 in the mask pattern 20 by deposition from an oblique upward direction in the +Y direction. This forms a Josephson junction element known as a Manhattan type.
[0041] In Example 1, the deposition of the superconducting film 14 was performed from an oblique upward direction in the X-axis direction, which is the stretching direction of the opening 22, and the deposition of the superconducting film 18 was performed from an oblique upward direction in the Y-axis direction, which is the stretching direction of the opening 24. However, the method is not limited to this case, and the deposition of the superconducting film 14 may also be performed from an oblique upward direction in a direction tilted within ±5° in a plan view from the X-axis direction, which is the stretching direction of the opening 22. The deposition of the superconducting film 18 may also be performed from an oblique upward direction in a direction tilted within ±5° in a plan view from the Y-axis direction, which is the stretching direction of the opening 24. [Examples]
[0042] Example 2 describes a method for manufacturing a Josephson junction element called a Dolan Bridge type. Figures 12(a) to 16(b) show the method for manufacturing a Josephson junction element according to Example 2. Figures 12(a), 13(a), 14(a), 15(a), and 16(a) are plan views showing the method for manufacturing a Josephson junction element according to Example 2. Figures 12(b), 13(b), 14(b), 15(b), and 16(b) are cross-sectional views AA of Figures 12(a), 13(a), 14(a), 15(a), and 16(a).
[0043] As shown in Figures 12(a) and 12(b), a mask layer 12 having a mask pattern 20a and a mask pattern 30 is formed on the substrate 10. The mask pattern 20a includes openings 22a and 24a and voids 26a. The mask pattern 30, as in Example 1, includes openings 32 and voids 36, and multiple mask patterns are provided around the mask pattern 20a at approximately constant intervals.
[0044] In the mask pattern 20a, the opening 22a extends in the X-axis direction, and the opening 24a extends in the Y-axis direction at an appropriate distance from the opening 22a in the X-axis direction, both formed in the upper layer 13a. The widths of the openings 22a and 24a are, for example, approximately the same, e.g., 100 nm to 300 nm. The void 26a is located below the openings 22a and 24a and is formed in the lower layer 13b with a larger shape than the openings 22a and 24a in a plan view. The portion of the upper layer 13a located between the openings 22a and 24b is formed to appear as if floating above the void 26a.
[0045] In the mask pattern 30, the length of the opening 32 in the X-axis direction is shorter than the length of the opening 24a in the X-axis direction, and the length of the opening 32 in the Y-axis direction is shorter than the length of the opening 22a in the Y-axis direction. The void 36 is located below the opening 32 and is formed in the lower layer 13b with a larger shape than the opening 32 in a plan view.
[0046] As shown in Figures 13(a) and 13(b), the mask layer 12 is used as a mask, and a superconducting film 14 is formed on the substrate 10 by deposition from an oblique upward direction in the -X direction, as indicated by the arrow 54. Because the superconducting film 14 is formed by deposition from an oblique upward direction in the -X direction, the superconducting film 14 formed in the void 26a is formed offset in the +X direction relative to the openings 22a and 24a. Since the length of the opening 32 in the mask pattern 30 in the X direction is shorter than the length of the opening 24a in the X direction, the formation of the superconducting film 14 in the void 36 is suppressed.
[0047] As shown in Figures 14(a) and 14(b), oxygen is introduced into the chamber while maintaining the vacuum state that was in place when the superconducting film 14 was formed, thereby oxidizing the surface of the superconducting film 14 and forming an insulating film 16 on the surface of the superconducting film 14.
[0048] As shown in Figures 15(a) and 15(b), the mask layer 12 is used as a mask, and a superconducting film 18 is formed on the substrate 10 by deposition from an oblique upward direction in the +X direction, as indicated by arrow 56. By appropriately adjusting the width of the opening 24a and / or the deposition angle from the oblique upward direction, a superconducting film 18 extending in the Y-axis direction is formed within the void 26a. Because the superconducting film 18 is formed by deposition from an oblique upward direction in the +X direction, the superconducting film 18 formed within the void 26a is formed offset in the -X direction relative to the openings 22a and 24a. As a result, a region 42 is formed in which the superconducting film 14 extending in the X-axis direction and the superconducting film 18 extending in the Y-axis direction overlap via the insulating film 16. Since the length of the opening 32 in the mask pattern 30 in the X-axis direction is shorter than the length of the opening 24a in the X-axis direction, the formation of the superconducting film 14 within the void 36 is suppressed.
[0049] As shown in Figures 16(a) and 16(b), the mask layer 12, the superconducting film 14, the insulating film 16, and the superconducting film 18 formed on the mask layer 12 are removed by the lift-off method. The mask layer 12 has openings 22a and 24a in the mask pattern 20a and an opening 32 in the mask pattern 30. Therefore, the stripping solution used in the lift-off method penetrates the mask layer 12 not only through the openings 22a and 24a but also through the opening 32. Thus, the lift-off processing time is shortened compared to when the opening 32 is not formed. The region where the superconducting film 14 extending in the X-axis direction and the superconducting film 18 extending in the Y-axis direction overlap via the insulating film 16 becomes a Josephson junction 46, and a Josephson junction element 100 is formed on the substrate 10.
[0050] According to Example 2, as shown in Figures 12(a) and 12(b), a mask layer 12 having a mask pattern 20a (first mask pattern) and a mask pattern 30 (second mask pattern) is formed on the substrate 10. The mask pattern 20a includes an opening 22a (first opening) extending in the X-axis direction and an opening 24a (second opening) extending in the Y-axis direction. The mask pattern 30 includes an opening 32 that is shorter than the opening 22a in the Y-axis direction and shorter than the opening 24a in the X-axis direction. As shown in Figures 13(a) and 13(b), using the mask layer 12 as a mask, a superconducting film 14 is formed on the substrate 10 in the mask pattern 20a by deposition (first deposition) from an oblique upward direction in the -X direction (first oblique upward direction). As shown in Figures 14(a) and 14(b), an insulating film 16 is formed on the surface of the superconducting film 14. As shown in Figures 15(a) and 15(b), the mask layer 12 is used as a mask, and the superconducting film 18 is formed on the mask pattern 20a by deposition (second deposition) from an oblique upward direction in the +X direction (second oblique upward direction). The superconducting film 18 is formed having a region 42 that overlaps with the superconducting film 14 via the insulating film 16. As shown in Figures 16(a) and 16(b), the mask layer 12 is removed by lift-off. This suppresses the formation of superconducting films 14 and 18 on the substrate 10 in the mask pattern 30, similar to Example 1, thus increasing the degree of freedom in the formation position of the mask pattern 30, and allowing the mask pattern 30 to be formed at a desired location. Since the peeling solution during lift-off penetrates the mask layer 12 not only from the openings 22 and 24 of the mask pattern 20 but also from the opening 32 of the mask pattern 30, the peeling time of the mask layer 12 can be shortened.
[0051] Figure 17(a) is an enlarged plan view of the vicinity of the mask pattern 30 in Figure 15(a), and Figure 17(b) is a cross-sectional view of AA in Figure 17(a). Note that in Figures 17(a) and 17(b), the insulating film 16 is very thin compared to the superconducting films 14 and 18, so it is not shown here. As shown in Figures 17(a) and 17(b), the superconducting film 14 is formed by deposition from an oblique upward direction in the -X direction, and the superconducting film 18 is formed by deposition from an oblique upward direction in the +X direction, so the superconducting films 14 and 18 are formed on the side surface of the opening 32. For this reason, the length L1 in the X-axis direction of the opening 32 is made greater than the sum of the thicknesses of the superconducting film 14 and the superconducting film 18 so that the peeling liquid during lift-off can penetrate from the opening 32 into the mask layer 12. From the perspective of allowing the stripping solution to penetrate the mask layer 12 through the opening 32, the length L1 of the opening 32 in the X-axis direction is preferably 1.5 times or more the sum of the thickness of the superconducting film 14 and the thickness of the superconducting film 18, more preferably 1.8 times or more, and even more preferably 2.0 times or more.
[0052] In Example 2, as shown in Figure 12(a), a mask layer 12 is formed having a mask pattern 20a that includes an opening 22a extending in the X-axis direction and an opening 24a extending in the Y-axis direction away from the opening 22a in the X-axis direction. As shown in Figure 13(a), a superconducting film 14 is formed on the substrate 10 in the mask pattern 20a by deposition from an oblique upward direction in the -X direction. As shown in Figure 15(a), a superconducting film 18 is formed on the substrate 10 in the mask pattern 20 by deposition from an oblique upward direction in the +X direction. This forms a Josephson junction element called a Dolan Bridge type.
[0053] Furthermore, in Example 2, similar to Example 1, the superconducting film 14 is not formed on the substrate 10 in the mask pattern 30, and the superconducting film 18 is not formed on the substrate 10 in the mask pattern 30. This increases the degree of freedom in the formation position of the mask pattern 30. Also, in Example 2, similar to Example 1, multiple mask patterns 30 are provided around the mask pattern 20. This allows the peeling liquid at lift-off to penetrate into the mask layer 12 through the openings 32 of the multiple mask patterns 30, thereby shortening the peeling time of the mask layer 12. Also, in Example 2, similar to Example 1, the multiple mask patterns 30 are arranged so that the spacing between adjacent mask patterns 30 is constant in the X-axis and Y-axis directions, without passing through the mask pattern 20. This allows the peeling liquid at lift-off to penetrate over a wide area of the mask layer 12 through the openings 32, rather than being concentrated in a part of the mask layer 12, thereby shortening the peeling time of the mask layer 12.
[0054] In Example 2, similar to Example 1, when forming the superconducting film 14, the incident angle of the film deposition material relative to the normal 11 of the substrate 10 when depositing from obliquely above in the -X direction is θ1. The thickness of the upper layer 13a of the mask layer 12 is T. The length of the opening 32 in the X-axis direction, which corresponds to the obliquely above in the -X direction, is L1. In this case, it is preferable that L1 ≤ T × tanθ1 is satisfied. When forming the superconducting film 18, the incident angle of the film deposition material relative to the normal 11 of the substrate 10 when depositing from obliquely above in the +X direction is θ2. The thickness of the upper layer 13a of the mask layer 12 is T. The length of the opening 32 in the X-axis direction, which corresponds to the obliquely above in the +X direction, is L1. In this case, it is preferable that L1 ≤ T × tanθ2 is satisfied. This suppresses the formation of superconducting films 14 and 18 on the substrate 10 in the mask pattern 30.
[0055] In Example 2, the deposition of the superconducting films 14 and 18 was shown as being carried out from an oblique upward direction in the X-axis direction, which is the stretching direction of the opening 22. However, the deposition of the superconducting films 14 and 18 may also be carried out from an oblique upward direction in a direction tilted within ±5° in a plan view from the X-axis direction, which is the stretching direction of the opening 22.
[0056] In Examples 1 and 2, the cases where the openings 22, 22a and 24, 24a extend in directions 90° apart are shown as examples, but they may also extend in directions slightly different from 90° (for example, 80° to 100° apart). Also, in Examples 1 and 2, the cases where the superconducting films 14 and 18 are formed using oblique deposition are shown as examples, but the superconducting films 14 and 18 may be formed by methods other than oblique deposition. Furthermore, in Examples 1 and 2, the cases where the superconducting films 14 and 18 are aluminum (Al) films are shown as examples, but other cases are also acceptable. For example, the superconducting films 14 and 18 may be niobium (Nb) films, niobium nitride (NbN) films, tantalum (Ta) films, tantalum nitride (TaN) films, or titanium nitride (TiN) films. The insulating film 16 is shown as an oxide film of the superconducting film 14 as an example, but other cases are also acceptable. [Examples]
[0057] Figure 18(a) is a plan view of the qubit device according to Embodiment 3, and Figure 18(b) is an enlarged view of the qubit in Figure 18(a). In Figures 18(a) and 18(b), hatching is applied to the metal film provided on the substrate 10 for clarity. As shown in Figures 18(a) and 18(b), the qubit device 300 has a qubit 60, a resonator 62, and a filter 64 provided on the substrate 10. The qubit 60 includes a Josephson junction element 100 connected between a circular electrode 70 and an outer electrode 72, and a capacitor 66 formed by the opposing circular electrode 70 and outer electrode 72. The Josephson junction element 100 is connected between the circular electrode 70 and the outer electrode 72 by a superconducting film 14 connected to the outer electrode 72 and a superconducting film 18 connected to the circular electrode 70. Thus, the qubit 60 comprises a transmon including a Josephson junction element 100 and a capacitor 66 connected in parallel to the Josephson junction element 100. The resonator 62 includes a meander structure coplanar line, one end of which is electrostatically coupled to the qubit 60. The other end of the resonator 62 is connected to a readout unit 68 via a filter 64. The readout unit 68 includes a through-hole 74 penetrating the substrate 10 and an electrode 76 provided on the inner surface of the through-hole 74.
[0058] Figures 19(a) to 21(c) are cross-sectional views showing a method for manufacturing a qubit device according to Example 3. As shown in Figure 19(a), a mask layer 80 made of, for example, a resist is formed on a substrate 10, and then the substrate 10 is bonded to a substrate 81. An opening 82 is formed in the mask layer 80. The substrate 10 is etched using the mask layer 80 as a mask to form through holes 74 that penetrate the substrate 10. For etching, for example, dry etching is used. The substrate 81 is used to cool the substrate 10 and suppress the temperature rise of the substrate 10 during etching to form the through holes 74 in the substrate 10, and / or for adsorption during the etching process.
[0059] As shown in Figure 19(b), after removing the mask layer 80 and the substrate 81, a superconducting film 83 is deposited on the upper and lower surfaces of the substrate 10, for example, using a sputtering method. The superconducting film 83 is, for example, a titanium nitride film with a thickness of about 100 nm. Subsequently, a superconducting film 84 is deposited on the upper and lower surfaces of the substrate 10 by oblique vacuum deposition. The superconducting film 84 is also formed on the inner surface of the through-holes 74. The superconducting film 84 is, for example, an aluminum film with a thickness of 300 nm.
[0060] As shown in Figure 19(c), after laminating dry film resist onto the upper and lower surfaces of the substrate 10, the dry film resist is patterned to form a mask layer 85 that covers the through-holes 74.
[0061] As shown in Figure 19(d), the superconducting film 84 is etched using the mask layer 85 as a mask. For etching, wet etching is used, for example. After that, the mask layer 85 is removed. As a result, an electrode 76 made of the superconducting film 84 is formed on the inner surface of the through hole 74.
[0062] As shown in Figure 20(a), after forming a resist film on the upper and lower surfaces of the substrate 10, the resist film is patterned to form a mask layer 86.
[0063] As shown in Figure 20(b), the superconducting film 83 is etched using the mask layer 86 as a mask. For etching, dry etching is used, for example. After that, the mask layer 86 is removed. As a result, the resonator 62 containing the coplanar line, the circular electrode 70 and outer electrode 72 included in the qubit 60 are formed by the superconducting film 83. Although not shown in the figure, the filter 64 and the like are also formed by the superconducting film 83.
[0064] As shown in Figure 20(c), a mask layer 12 including an upper layer 13a and a lower layer 13b is formed on the substrate 10. The mask layer 12 has a mask pattern 20 including an opening 24 and a void 26, and a mask pattern 30 including an opening 32 and a void 36. Note that, as shown in Figure 1(a), etc., the mask pattern 20 also includes the opening 22, but the opening 22 is not shown in Figure 20(c).
[0065] As shown in Figure 21(a), the mask layer 12 is used as a mask, and a superconducting film 14 is formed on the substrate 10 by depositing the film from an oblique upward direction in the stretching direction of the opening 22. As a result, as described in Example 1, a superconducting film 14 extending in the stretching direction of the opening 22 is formed in the void 26. Since the opening 32 is small, the formation of the superconducting film 14 in the void 36 is suppressed. Subsequently, while maintaining the vacuum state at which the superconducting film 14 was formed, oxygen is introduced into the chamber to oxidize the surface of the superconducting film 14, thereby forming an insulating film 16 on the surface of the superconducting film 14.
[0066] As shown in Figure 21(b), a superconducting film 18 is formed on the substrate 10 by depositing the film from an oblique upward direction in the stretching direction of the opening 24, using the mask layer 12 as a mask. As a result, a superconducting film 18 extending in the stretching direction of the opening 24 is formed within the void 26, as described in Example 1. Since the opening 32 is small, the formation of a superconducting film 18 within the void 36 is suppressed.
[0067] As shown in Figure 21(c), the mask layer 12, the superconducting film 14, the insulating film 16, and the superconducting film 18 formed on the mask layer 12 are removed by the lift-off method. The mask layer 12 has openings 22 and 24 in the mask pattern 20 and an opening 32 in the mask pattern 30. Therefore, the stripping solution used for lift-off penetrates not only through the openings 22 and 24 but also through the opening 32, removing the mask layer 12. A Josephson junction element 100 is formed on the substrate 10, in which the superconducting film 14 and the superconducting film 18 overlap with the insulating film 16 in between.
[0068] According to Example 3, the Josephson junction element 100 included in the qubit 60 connected to the resonator 62 and filter 64 is formed by the method shown in Example 1. This makes it possible to shorten the peeling time of the mask layer 12 used for forming the Josephson junction element 100.
[0069] In Example 3, the Josephson junction element 100 is not limited to being formed by the method shown in Example 1, but may also be formed by the method shown in Example 2.
[0070] Although embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. [Explanation of Symbols]
[0071] 10 circuit boards 11 Normal 12 mask layers 13a upper layer 13b Lower layer 14 Superconducting film 16 Insulating film 18 Superconducting film 20, 20a Mask Pattern 22, 22a opening 24, 24a opening 26, 26a void 30 Mask Patterns 32 openings 36 void 40 areas 42 areas 46 Josephson junction 58 Metal film 60 qubits 62 Resonator 64 filters 66 Capacitors 68 Reading section 70 circular electrodes 72 Peripheral electrode 74 Through holes 76 Electrode 80 mask layers 81 circuit boards 82 Aperture 83, 84 Superconducting film 85, 86 Mask layer 100 Josephson junction elements 112 Mask Layers 300-qubit device
Claims
1. A step of forming a mask layer on a substrate having a first mask pattern including a first opening extending in a first direction and a second opening extending in a second direction intersecting the first direction, and a second mask pattern including a third opening shorter than the second opening in the first direction and shorter than the first opening in the second direction, A step of forming a first superconducting film on the substrate in the first mask pattern by first film deposition from diagonally above the substrate, using the mask layer as a mask, A step of forming an insulating film on the surface of the first superconducting film, A step of forming a second superconducting film having a region that overlaps with the first superconducting film via the insulating film in the first mask pattern by second film deposition from diagonally above the substrate, using the mask layer as a mask, A method for manufacturing a Josephson junction element, comprising the step of removing the mask layer by lift-off.
2. A step of forming a mask layer on a substrate, comprising: a first mask pattern having an upper layer and a lower layer, the upper layer having a first opening extending in a first direction and a second opening extending in a second direction intersecting the first direction, and a first void formed in the lower layer below the first and second openings and larger in plan view than the first and second openings; and a second mask pattern formed in the upper layer having a third opening shorter in the first direction and shorter in the second direction than the first opening, and a second void formed in the lower layer below the third opening and larger in plan view than the third opening; A step of forming a first superconducting film on the substrate in the first mask pattern by first film deposition from diagonally above the substrate, using the mask layer as a mask, A step of forming an insulating film on the surface of the first superconducting film, A step of forming a second superconducting film having a region that overlaps with the first superconducting film via the insulating film in the first mask pattern by second film deposition from diagonally above the substrate, using the mask layer as a mask, A method for manufacturing a Josephson junction element, comprising the step of removing the mask layer by lift-off.
3. In the step of forming the first superconducting film, the first superconducting film is not formed on the substrate in the second mask pattern. A method for manufacturing a Josephson junction element according to claim 1 or 2, wherein in the step of forming the second superconducting film, the second superconducting film is not formed on the substrate in the second mask pattern.
4. The method for manufacturing a Josephson junction element according to claim 1 or 2, wherein the step of forming the mask layer is to form the mask layer having a plurality of second mask patterns provided around the first mask pattern.
5. The method for manufacturing a Josephson junction element according to claim 4, wherein the step of forming the mask layer is to form the mask layer having a plurality of second mask patterns in which adjacent second mask patterns are arranged in the first and second directions without passing through the first mask pattern, with a constant spacing between them.
6. The step of forming the mask layer is to form the mask layer having an upper layer and a lower layer, wherein the first mask pattern includes a first opening and a second opening formed in the upper layer, and a first void formed in the lower layer below the first and second openings and larger in plan view than the first and second openings, and the second mask pattern includes a third opening formed in the upper layer, and a second void formed in the lower layer below the third opening and larger in plan view than the third opening, When the angle of incidence of the film deposition material with respect to the normal of the substrate in the first film deposition is θ1, the length of the third opening in the direction corresponding to the diagonally upward in the first film deposition is L1, and the thickness of the upper layer is T, then L1 ≤ T × tanθ1 is satisfied. A method for manufacturing a Josephson junction element according to claim 1, wherein, when the angle of incidence of the film deposition material with respect to the normal of the substrate in the second film deposition is θ2, the length of the third opening in the direction corresponding to the diagonally upward in the second film deposition is L2, and the thickness of the upper layer is T, L2 ≤ T × tanθ2.
7. The step of forming the mask layer is to form the mask layer having the first mask pattern in which the first opening and the second opening intersect, The step of forming the first superconducting film involves forming the first superconducting film by first film deposition from diagonally above the substrate in the first direction, The method for manufacturing a Josephson junction element according to claim 1 or 2, wherein the step of forming the second superconducting film is to form the second superconducting film by second film deposition from obliquely above the substrate in the second direction.
8. The method for manufacturing a Josephson junction element according to claim 7, wherein the step of forming the mask layer is to form a mask layer in which the length of the third opening in the first direction is greater than the thickness of the first superconducting film and the length of the third opening in the second direction is greater than the thickness of the second superconducting film.
9. The step of forming the mask layer involves forming the mask layer having a first mask pattern in which the second opening is separated from the first opening in the first direction, The step of forming the first superconducting film involves forming the first superconducting film by first film deposition from diagonally above the substrate in the first direction, The method for manufacturing a Josephson junction element according to claim 1 or 2, wherein the step of forming the second superconducting film is to form the second superconducting film by forming the second film from an oblique upward direction to the substrate, which is opposite to the oblique upward direction to the substrate in the first film formation.
10. The method for manufacturing a Josephson junction element according to claim 9, wherein the step of forming the mask layer is to form a mask layer in which the length of the third opening in the first direction is greater than the sum of the thickness of the first superconducting film and the thickness of the second superconducting film.
11. The step of forming the first superconducting film involves forming the first superconducting film by oblique deposition, The method for manufacturing a Josephson junction element according to claim 1 or 2, wherein the step of forming the second superconducting film is to form the second superconducting film by oblique deposition.
12. A process for forming a Josephson junction element, A step of forming a capacitor connected in parallel to the Josephson junction element, The process includes forming a resonator and a filter connected to a qubit that includes the Josephson junction element and the capacitor, The process of forming the Josephson junction element is as follows: A step of forming a mask layer on a substrate having a first mask pattern including a first opening extending in a first direction and a second opening extending in a second direction intersecting the first direction, and a second mask pattern including a third opening shorter than the second opening in the first direction and shorter than the first opening in the second direction, A step of forming a first superconducting film on the substrate in the first mask pattern by first film deposition from diagonally above the substrate, using the mask layer as a mask, A step of forming an insulating film on the surface of the first superconducting film, A step of forming a second superconducting film having a region that overlaps with the first superconducting film via the insulating film in the first mask pattern by second film deposition from diagonally above the substrate, using the mask layer as a mask, A method for manufacturing a qubit device, comprising the step of removing the mask layer by lift-off.