Preparation method of superconducting layer, preparation method of Josephson junction and quantum circuit

Abstract

The invention discloses a preparation method of a superconducting layer, a preparation method of a Josephson junction and a quantum circuit, and the manufacturing method of the superconducting layer comprises the following steps: carrying out at least two times of oblique evaporation deposition on a first deposition window of a mask layer formed on a substrate to form the superconducting layer, the deposition window is formed by etching or exposing and developing the mask layer; wherein the inclined evaporation direction each time is a first direction and a second direction which are selected and are different; in the at least two times of oblique evaporation, the oblique evaporation along the first direction and the oblique evaporation along the second direction are respectively executed at least once, and the times of respective execution are selected to be combined so as to eliminate or reduce uneven thickness of the superconducting layer caused by the oblique evaporation only from the first direction or the oblique evaporation only from the second direction. According to the invention, the thickness uniformity of the superconducting layer in the length direction can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of quantum computers, and in particular to a method for preparing a superconducting layer, a method for preparing a Josephson junction, and a quantum circuit. Background Art

[0002] Quantum computers are physical devices that follow the laws of quantum mechanics to perform high-speed mathematical and logical operations, store and process quantum information. The main characteristics of quantum computers are fast operation speed, strong information processing capabilities, and a wide range of applications. Quantum chips are the core components of quantum computers.

[0003] The quantum chip is distributed with superconducting quantum circuits, and the Josephson junction is the key device of the superconducting quantum circuit. The Josephson junction, or superconducting tunnel junction, is generally composed of two superconducting layers with an extremely thin insulating layer (barrier layer) sandwiched between them. In it, superconducting electrons can pass through the semiconductor or insulating layer film from one side to the other side through the tunnel effect. The existing preparation method of the Josephson junction usually adopts the oblique evaporation coating process, and the coating adopts electron beam evaporation, which is to use electron beam to directly heat the evaporated material under vacuum conditions, so that the evaporated material is vaporized and transported to the substrate, and condensed on the substrate to form a thin film. In the coating process, there are strict requirements on the inclination angle of the substrate. First, the first superconducting layer is coated on the substrate in one direction, and then the position of the substrate is adjusted, and the second superconducting layer is coated on the substrate from another direction. In the coating process, the uniformity of thickness and roughness is not easy to control. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a superconducting layer, a method for preparing a Josephson junction and a quantum circuit, which are used to solve the problem that the uniformity of thickness and roughness is not easy to control in the existing coating process.

[0005] A method for manufacturing a superconducting layer comprises the following steps:

[0006] Performing at least two oblique evaporation depositions on a first deposition window of a mask layer formed on a substrate to form a superconducting layer, wherein the deposition window is formed by etching or exposing and developing the mask layer;

[0007] Wherein, the direction of the oblique evaporation each time is a first direction and a second direction which are selected and different;

[0008] In the at least two oblique evaporations, the oblique evaporation along the first direction and the oblique evaporation along the second direction are each performed at least once, and the number of times each is performed is selected to combine to eliminate or reduce the uneven thickness of the superconducting layer caused by the oblique evaporation only from the first direction or only from the second direction.

[0009] In one embodiment, the first deposition window is in the shape of an elongated strip, the first direction is from one end of the first deposition window toward the other end, and the second direction is from the other end toward the one end.

[0010] In one embodiment, the deposition in the first direction is performed multiple times, and the angle of each deposition in the first direction is different from that of other depositions at least once.

[0011] In one embodiment, the angles of the oblique evaporation in the first direction and the second direction are symmetrical, and the number of oblique evaporations is the same.

[0012] In one embodiment, oblique evaporation is performed once in both the first direction and the second direction.

[0013] A method for manufacturing a Josephson junction comprises the following steps:

[0014] A mask layer on the substrate forms a first deposition window and a second deposition window, and a first superconducting layer is prepared in the first deposition window using the above-mentioned method for preparing a superconducting layer;

[0015] forming a barrier layer on the first superconducting layer at the intersection of the first deposition window and the second deposition window;

[0016] A second superconducting layer is deposited on the second deposition window to obtain a Josephson junction at the intersection.

[0017] In one embodiment, the first deposition window and the second deposition window form an intersection, and the evaporated material covers the intersection each time oblique evaporation is performed.

[0018] In one embodiment, the mask layer on the substrate forms a first deposition window, comprising:

[0019] Apply two layers of photoresist evenly on the surface of the substrate to form a mask layer;

[0020] Determining a first region on the mask layer for forming a first deposition window and a second region for forming a second deposition window;

[0021] The mask layer in the first area is etched or exposed and developed to retain the suspended gel structure in the first area, wherein the suspended gel structure includes a left suspended gel structure extending outward from the left side wall of the second area to a set width and a right suspended gel structure extending outward from the right side wall of the second area to a set width; wherein the left suspended gel structure and the right suspended gel structure are structures in which the lower layer of photoresist on the substrate has been removed and the upper layer of photoresist on the lower layer of photoresist is retained, and are used to prevent the evaporated material from evaporating from the second deposition window onto the substrate when oblique evaporation deposition is performed on the first deposition window.

[0022] In one embodiment, depositing the second deposition window to form a second superconducting layer to obtain a Josephson junction at the intersection comprises:

[0023] forming a second superconducting layer by depositing the second deposition window by at least two oblique evaporations or by straight evaporation to obtain a Josephson junction at the intersection;

[0024] When the second deposition window is subjected to at least two oblique evaporations, the direction of each oblique evaporation is a third direction and a fourth direction that are selected and different;

[0025] In the at least two oblique evaporations, the oblique evaporation along the third direction and the oblique evaporation along the fourth direction are each performed at least once, and the number of times each is performed is selected to combine to eliminate or reduce the uneven thickness of the superconducting layer caused by the oblique evaporation only from the third direction or the oblique evaporation only from the fourth direction.

[0026] A quantum circuit comprises a Josephson junction manufactured by the above-mentioned method for manufacturing a Josephson junction. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the principle of evaporation deposition in the prior art;

[0028] Figure 2 A schematic diagram of the structure of deposition in the first deposition window and the second deposition window when preparing a Josephson junction provided by an embodiment of the present invention;

[0029] Figure 3 This is a top view of the lower photoresist mask layer after etching or exposure and development in this embodiment.

[0030] Figure 4 A schematic diagram of the deposition effect when oblique evaporation in the first direction and the second direction is used in the first deposition window when preparing a Josephson junction according to an embodiment of the present invention;

[0031] Figure 5 A schematic diagram of the Josephson junction effect prepared by the present invention;

[0032] In the reference numerals:

[0033] 1. Substrate; 21. Lower photoresist; 22. Upper photoresist; 221. Left suspended photoresist structure; 222. Right suspended photoresist structure; 31. First deposition window; 32. Second deposition window; 41. First deposition layer; 42. Second deposition layer; 5. Barrier layer; 6. Second superconducting layer. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application, and cannot be interpreted as limitations on the present application.

[0035] In the description of the present invention, it is to be understood that the terms "first", "second", "upper", "lower", "left", "right", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or precedence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0036] Quantum computing is a rapidly emerging technology that uses the laws of quantum mechanics to solve problems that are too complex for classical computers. Classical processors use bits to perform operations. Quantum computers use quantum bits (CUE bits) to run multi-dimensional quantum algorithms. In the field of quantum computing research, superconducting quantum bit systems are considered to be one of the most promising systems for realizing quantum computing. Superconducting quantum bits, as key components of quantum chips, are mainly superconducting circuits containing one or more Josephson junctions. The Josephson junction is a structure composed of two superconductors sandwiched by a very thin barrier layer 5 (thickness ≤ Cooper electron pair coherence length). When the thickness of the insulating layer is as thin as a few nanometers, a significant electron pair tunneling effect, namely the Josephson effect, will occur.

[0037] In order to realize the preparation of the Josephson junction, the conventional process is to form a mask layer on the substrate 1, and use exposure, development, etching and other processes to form a first deposition window 31 and a second deposition window 32 perpendicular to each other for preparing the Josephson junction on the mask layer, and then coat the corresponding first deposition window 31 and second deposition window 32 by two oblique evaporations to form the corresponding first superconducting layer and second superconducting layer 6. Since the coating adopts electron beam evaporation, the principle of electron beam evaporation is as follows: Figure 1As shown, an electron beam is used to directly heat the target material, i.e., the evaporation material, under vacuum conditions, so that the evaporation material is vaporized and transported to the substrate, and condensed on the substrate to form a thin film. After research, it was found that the thickness of the evaporation material deposited on the substrate varies with the distance from the target material to the substrate. The farther the distance, the smaller the thickness of the film condensed on the substrate. When the first superconducting layer and the second superconducting layer 6 are prepared by the oblique evaporation process, due to the different distances from different positions of the substrate to the crucible, this leads to large differences in the thickness of the film at different positions when the first superconducting layer is prepared by oblique evaporation, and there are also differences in the roughness of the surface layer. The difference in thickness and roughness also makes the barrier layer 5 formed by in-situ oxidation different, which is specifically manifested in that the resistance of the Josephson junction at room temperature fluctuates greatly, and the decoherence time at low temperatures is also good or bad. In summary, the quality of the Josephson junction is closely related to the preparation structure of the superconducting layer.

[0038] In order to optimize the superconducting layer, the present application embodiment discloses a method for preparing a superconducting layer, comprising the following steps:

[0039] Performing at least two oblique evaporation depositions on a first deposition window 31 of a mask layer formed on a substrate 1 to form a superconducting layer, wherein the deposition window is formed by etching or exposing and developing the mask layer;

[0040] Wherein, the direction of the oblique evaporation each time is a first direction and a second direction which are selected and different;

[0041] In the at least two oblique evaporations, the oblique evaporation along the first direction and the oblique evaporation along the second direction are each performed at least once, and the number of times each is performed is selected to combine to eliminate or reduce the uneven thickness of the superconducting layer caused by the oblique evaporation only from the first direction or only from the second direction.

[0042] Since the thickness of the evaporated material deposited on the substrate varies with the distance from the target material to the substrate, the greater the distance, the smaller the thickness of the thin film condensed on the substrate. Therefore, during each oblique evaporation in the first direction or the second direction, the thickness of the deposited material in the first deposition window 31 will be uneven. In the at least two oblique evaporations described in the present application, the oblique evaporation along the first direction and the oblique evaporation along the second direction are each performed at least once, and the number of times each is performed is selected to be combined, thereby eliminating or reducing the problem of uneven thickness of the superconducting layer caused by oblique evaporation from only one direction.

[0043] In this embodiment, the first deposition window 31 is in the shape of a long strip. In order to improve the efficiency and effect of oblique evaporation, the first direction is from one end of the first deposition window 31 toward the other end, and the second direction is from the other end toward the one end. The opposite directions can better reduce the problem of uneven thickness of the superconducting layer caused by oblique evaporation in one direction.

[0044] In some embodiments of the present invention, the deposition in the first direction is performed multiple times, and at least one deposition angle in the first direction is different from the other deposition angles. Oblique evaporation at different deposition angles can improve the flatness of the first superconducting layer.

[0045] In some embodiments of the present invention, the angles of the oblique evaporation in the first direction and the second direction are symmetrical, and the number of oblique evaporations is the same. This arrangement can further improve the flatness of the first superconducting layer. In order to simplify the implementation process and avoid oxidation of the superconducting layer due to excessive exposure time during the preparation of the superconducting layer, the optimal solution is to perform oblique evaporation once in each of the first direction and the second direction, that is, the first oblique evaporation and the second oblique evaporation.

[0046] In summary, what the present application protects is that in the at least two oblique evaporations, the oblique evaporation along the first direction and the oblique evaporation along the second direction are each performed at least once, and the number of times each is performed is selected to combine to eliminate or reduce the uneven thickness of the superconducting layer caused by the oblique evaporation only from the first direction or only from the second direction. The above-described schemes can all be implemented to obtain the effect of eliminating or reducing the uneven thickness of the superconducting layer caused by the oblique evaporation only from the first direction or only from the second direction. Therefore, the above-mentioned schemes all fall within the scope of protection of the present application.

[0047] Combined with Figure 2-4 The embodiment of the present invention further provides a method for preparing a Josephson junction, comprising the steps of:

[0048] S100, forming a first deposition window 31 and a second deposition window 32 on a mask layer on a substrate 1, and preparing a first superconducting layer in the first deposition window 31;

[0049] S200, forming a barrier layer 5 on the first superconducting layer at the intersection of the first deposition window 31 and the second deposition window 32;

[0050] S300 , depositing a second superconducting layer 6 in the second deposition window 32 to obtain a Josephson junction at the intersection.

[0051] In the present application, forming a first deposition window 31 and a second deposition window 32 on a mask layer on a substrate 1 in step S100 includes:

[0052] S101, evenly coating the surface of substrate 1 with upper and lower layers of photoresist to form a mask layer; in one embodiment, the substrate 1 uses a silicon wafer, and the silicon wafer is cleaned and dried to remove pollutants and water vapor on the original silicon wafer. In an optimized manner, the dried silicon wafer is primed to make the surface of the silicon wafer hydrophobic and enhance the adhesion between the surface of the silicon wafer and the photoresist; specifically, evenly coating the surface of substrate 1 with photoresist to form upper and lower layers of photoresist, wherein an upper layer of photoresist 22 and a lower layer of photoresist 21 are used as mask layers, and the substrate 1, the lower layer of photoresist 21, and the upper layer of photoresist 22 are stacked in sequence;

[0053] S102, determining a first region for forming a first deposition window 31 and a second region for forming a second deposition window 32 located on the mask layer; the first region and the second region are perpendicular and intersecting;

[0054] S103, etching or exposing and developing the mask layer in the first area, retaining the suspended gel structure in the first area, the suspended gel structure comprising a left suspended gel structure 221 formed by extending outward from the left side wall of the second area to a set width, and a right suspended gel structure 222 formed by extending outward from the right side wall of the second area to a set width; wherein the left suspended gel structure 221 and the right suspended gel structure 222 are both structures in which the lower layer photoresist 21 on the substrate 1 has been removed and the upper layer photoresist 21 is retained, so as to prevent the evaporated material from evaporating from the second deposition window 32 to the substrate 1 when the first deposition window 31 is subjected to oblique evaporation deposition;

[0055] The mask layer in the second region is etched or exposed and developed to form a second deposition window 32 .

[0056] In step S103, the mask layer of the first region is etched or exposed and developed to retain the suspended structure in the first region, wherein the suspended structure includes a left suspended structure 221 extending outward from the left side wall of the second region to a set width and a right suspended structure 222 extending outward from the right side wall of the second region to a set width; the steps include:

[0057] S1031, etching or exposing and developing the mask layer in the first region, retaining the mask layer extending outwardly from the left side wall of the second region by a set width as a first mask portion, and retaining the mask layer extending outwardly from the right side wall of the second region by a set width as a second mask portion, wherein the first mask portion and the second mask portion are both located in the first region;

[0058] S1032, etching or exposing and developing the mask layer in the second region;

[0059] S1033 , exposing and developing the lower photoresist 21 of the first mask part and the second mask part to obtain corresponding left-hanging resist structure 221 and right-hanging resist structure 222 , so that the first deposition window 31 is continuous.

[0060] In step S103, taking the exposure and development of the first area and the second area as an example, two embodiments are disclosed in this scheme. In the first embodiment, the lower photoresist 21 can be exposed by a low-dose electron beam, and the upper photoresist 22 can be exposed by a high-dose electron beam. The high dose and low dose refer to the total amount of charge of the electrons irradiated on the unit area during the exposure process. The low-dose electron beam is relative to the high-dose electron beam. Under the same other exposure settings, the high and low doses are manifested as different exposure times. The high dose and low dose are not used to limit the exposure characteristics of the upper photoresist 22 and the lower photoresist 21, but are only used for the characteristics that the combination of the upper photoresist 22 and the lower photoresist 21 should have, providing conditions for photolithography to form a suspension. In another embodiment, a non-photosensitive material is selected to be coated on the substrate 1 to form the lower photoresist 21, and a photosensitive material is coated on the lower photoresist 21 to form the upper photoresist 22.

[0061] The steps for obtaining the suspended gel structure based on the first embodiment used when exposing and developing the first area and the second area are as follows: the upper photoresist 22 and the lower photoresist 21 are exposed according to a set shape by controlling the electron beam dose to form a mask structure pattern, and a high-dose electron beam is used for exposure to remove the upper photoresist 22 and the lower photoresist 21 at the positions of the first deposition window 31 and the second deposition window 32 of the first mask part and the second mask part; the lower photoresist 21 of the first mask part and the second mask part is exposed by a low-dose electron beam, and the lower photoresist 21 is removed according to the set position to form a suspended gel structure. The steps of obtaining the suspended gel structure based on the second embodiment used when exposing and developing the first area and the second area are as follows: according to the set mask structure pattern, two different developers are used for development twice. The first development process uses an electron beam developer to remove the first deposition window 31 to remove the upper photoresist 22 of the first mask part and the second mask part, and the upper photoresist 22 at the position of the second deposition window 32. The second development process uses a positive photoresist developer to remove the lower photoresist 21 of the first deposition window 31 and the second deposition window 32, and form a suspended gel structure by controlling the dissolution time of the lower layer of glue. The effect diagram after the lower layer of photoresist is etched or exposed and developed is as shown in FIG. Figure 3 shown.

[0062] The present application ensures that the evaporated material covers the intersection each time the oblique evaporation is performed and prevents the evaporated material from being deposited on the substrate 1 from the second deposition window 32 when depositing the first deposition window 31 by setting the width, the tilt angle during oblique evaporation, the thickness of the upper photoresist 22, and the thickness of the lower photoresist 21, thereby effectively improving the flatness of the second superconducting layer 6 in the second deposition window 32.

[0063] In the present application, the step S100 of preparing the first superconducting layer in the first deposition window 31 includes the following steps:

[0064] Performing at least two oblique evaporation depositions on a first deposition window 31 of a mask layer formed on a substrate 1 to form a superconducting layer, wherein the deposition window is formed by etching or exposing and developing the mask layer;

[0065] Wherein, the direction of the oblique evaporation each time is a first direction and a second direction which are selected and different;

[0066] In the at least two oblique evaporations, the oblique evaporation along the first direction and the oblique evaporation along the second direction are each performed at least once, and the number of times each is performed is selected to combine to eliminate or reduce the uneven thickness of the superconducting layer caused by the oblique evaporation only from the first direction or only from the second direction.

[0067] In this embodiment, the first deposition window 31 is in the shape of a long strip, the first direction is from one end of the first deposition window 31 toward the other end, and the second direction is from the other end toward the one end. During electron beam evaporation, the evaporation thickness gradually decreases as the distance from the target position increases. One oblique evaporation causes the deposition to be thick near the target and thin far from the target. In this application, multiple oblique evaporations are performed, and the projections of all the oblique evaporation directions on the substrate 1 coincide with the first deposition window 31, and the vector component direction of at least one oblique evaporation is opposite to the vector component direction of other oblique evaporations, and the vector component direction is parallel to the substrate 1. Compared with one oblique evaporation to prepare the first superconducting layer, in the at least two oblique evaporations in this application, the oblique evaporation along the first direction and the oblique evaporation along the second direction are each performed at least once, and the number of times each is performed is selected to combine, which can reduce the thickness change of the evaporated material caused by the change in the distance from the target to the substrate, resulting in the thickness of the first superconducting layer in the length direction.

[0068] In some embodiments of the present invention, the deposition in the first direction is performed multiple times, and at least one angle of each deposition in the first direction is different from the other deposition angles.

[0069] In some embodiments of the present invention, the angles of the oblique evaporation in the first direction and the second direction are symmetrical, and the number of oblique evaporations is the same.

[0070] In summary, if Figure 2 As shown, a preferred embodiment of the present application is that oblique evaporation is performed once in each of the first direction and the second direction, namely, the first oblique evaporation and the second oblique evaporation.

[0071] During the first oblique evaporation and the second oblique evaporation, the evaporated material covers the overlapping surface of the first deposition window 31 and the second deposition window 32. Figure 4 As shown, during the first oblique evaporation, the evaporated material covers the overlapping surface of the first deposition window 31 and the second deposition window 32 from the left side wall of the left suspension structure 221, and during the second oblique evaporation, the evaporated material covers the overlapping surface of the first deposition window 31 and the second deposition window 32 from the right side wall of the right suspension structure 222. This embodiment can better prevent the evaporated material from being deposited in the second deposition window 32 when the first superconducting layer is formed. The first oblique evaporation allows the evaporated material to be deposited only on the left side wall of the right suspension structure 222 when passing between the left suspension structure 221 and the right suspension structure 222. The second oblique evaporation allows the evaporated material to be deposited only on the right side wall of the left suspension structure 221 when passing between the left suspension structure 221 and the right suspension structure 222, and cannot be deposited in the second deposition window 32. The left suspension structure 221, the right suspension structure 222, the left side wall, and the right side wall are all based on Figure 2 and Figure 4 The description direction from the perspective of , which is used to distinguish similar objects.

[0072] In one of the embodiments, in order to achieve complementary deposition thicknesses of the first oblique evaporation and the second oblique evaporation in the first deposition window 31, the angles between the first oblique evaporation and the second oblique evaporation and the substrate 1 are symmetrical about the second deposition window 32, thereby ensuring that the deposition thicknesses plated on the inner side walls opposite to the left suspended gel structure 221 and the right suspended gel structure 222 are the same, avoiding the difference in line width of the second superconducting layer 6 caused by different deposition thicknesses plated on the side walls of the photoresist due to one oblique evaporation, because the distances from the substrate 1 to the target material are different, and the actual thicknesses plated on the side walls of the photoresist are different, which will lead to differences in line widths of the second superconducting layer 6, resulting in different actual areas of the Josephson junction and more uneven junction resistance. In the present application, the angles between the first oblique evaporation and the second oblique evaporation and the substrate 1 are symmetrical about the second deposition window 32, which can ensure that the sum of the deposition thicknesses plated on the left photoresist and the right photoresist is constant, so that the thicknesses plated on the side walls of the photoresist can be ensured to be similar, so that the line widths of the second superconducting layer 6 in the Josephson junctions prepared multiple times are similar. Using the above method, after one first oblique evaporation and one second oblique evaporation, the thickness of the first superconducting layer is 2sinθ*d, where d is the thickness in the vertical direction during each coating, and θ is the angle between the coating direction and the substrate. The thickness and roughness deviations of the deposited materials at different positions are smaller, which can effectively ensure that the surface of the deposited material forming the barrier layer 5 is more uniform, thereby effectively improving the stability of the junction resistance.

[0073] In order to ensure the flatness of the first superconducting layer and the second superconducting layer 6 of the Josephson junction, the evaporated materials cover the overlapping surfaces of the first deposition window 31 and the second deposition window 32 during the first oblique evaporation and the second oblique evaporation. The present application collaboratively determines the three factors of the angle between the oblique evaporation and the substrate 1, the thickness of the upper photoresist 22 and the lower photoresist 21, and the distance between the left suspended structure 221 and the right suspended structure 222.

[0074] In one embodiment, the method of depositing the first superconducting layer and the second superconducting layer 6 is magnetron sputtering.

[0075] In one embodiment, the barrier layer 5 is formed on the first superconducting layer at the intersection of the first deposition window 31 and the second deposition window 32 by oxidation in an oxidation chamber. In another embodiment, the barrier layer 5 material is directly sputtered by magnetron sputtering.

[0076] Optionally, the second deposition window 32 may be deposited to form the second superconducting layer 6 by direct evaporation or oblique evaporation. In the embodiment in which oblique evaporation is used to prepare the second superconducting layer 6, the second deposition window 32 is deposited by at least two oblique evaporations or by direct evaporation to form the second superconducting layer 6 to obtain a Josephson junction at the intersection; when the second deposition window 32 is subjected to at least two oblique evaporations, the direction of each oblique evaporation is a selected and different third direction and fourth direction; in the at least two oblique evaporations, the oblique evaporation along the third direction and the oblique evaporation along the fourth direction are each performed at least once, and the number of times each is performed is selected to combine to eliminate or reduce the uneven thickness of the superconducting layer caused by only oblique evaporation from the third direction or only oblique evaporation from the fourth direction. The thickness of the second superconducting layer 6 must be greater than twice the thickness of the first superconducting layer. In the embodiment in which direct evaporation is used to prepare the second superconducting layer 6, the preparation of the second superconducting layer 6 can be completed at one time. In another embodiment, the third oblique evaporation and the fourth oblique evaporation may be performed multiple times, so that the thickness of the second superconducting layer 6 at different positions is more uniform while ensuring that the thickness of the second superconducting layer 6 meets the requirements.

[0077] Optionally, the first superconducting layer and the second superconducting layer 6 may be made of aluminum, niobium, or tantalum. In one embodiment, the first superconducting layer and the second superconducting layer 6 may be made of niobium, and the barrier layer 5 may be made of NbN.

[0078] The method for preparing a Josephson junction further comprises the steps of:

[0079] S007 , stripping the photoresist; stripping the remaining upper photoresist 22 and lower photoresist 21 .

[0080] The Josephson junction obtained by the above steps is Figure 5As shown, a first deposition layer 41 is obtained by oblique evaporation in a first direction, and a second deposition layer 42 is obtained by oblique evaporation in a second direction, thereby forming a first superconducting layer, and then a barrier layer 5 is obtained after oxidation, and a second superconducting layer 6 is directly evaporated on the barrier layer 5 to finally form a Josephson junction. In this scheme, the first direction oblique evaporation is deposited from the left side to the right side of the first deposition window, and the left side deposition thickness D1 is greater than the right side deposition thickness D2. After the second direction oblique evaporation, that is, deposition from the right side to the left side of the first deposition window, the thickness of the right side deposition is greater than the left side deposition thickness. Therefore, after oblique evaporation on both sides, the plane of the first superconducting layer located at the intersection is roughly flush with the substrate.

[0081] The embodiment of the present application further proposes a quantum circuit, including a first superconducting device, a second superconducting device and a Josephson junction, wherein the Josephson junction includes:

[0082] The first superconducting layer, exemplarily, in a specific manner, the material of the first superconducting layer is aluminum or niobium or tantalum, and the first superconducting layer is formed by performing at least two oblique evaporation depositions on a first deposition window of a mask layer formed on a substrate 1; wherein the direction of each oblique evaporation is a first direction and a second direction that are selected and different; in the at least two oblique evaporations, the oblique evaporation along the first direction and the oblique evaporation along the second direction are each performed at least once, and the number of times each is performed is selected to combine to eliminate or reduce the uneven thickness of the superconducting layer caused by the oblique evaporation only from the first direction or only from the second direction;

[0083] a first connection layer, formed integrally with the first superconducting layer and connected to the first superconducting device, so that the first superconducting layer is electrically connected to the first superconducting device, and the first connection layer and the first superconducting layer can be prepared simultaneously;

[0084] The barrier layer 5 is located on the first superconducting layer, and the barrier layer 5 is formed by oxidizing the first superconducting layer in an oxidation chamber or directly sputtering the barrier layer 5 material by magnetron sputtering.

[0085] The second superconducting layer 6 and the first superconducting layer overlap, and the barrier layer 5 is located at the overlapping surface, so as to form the Josephson junction.

[0086] The second connection layer is formed integrally with the second superconducting layer 6 and connected to the second superconducting device, so that the second superconducting layer 6 is electrically connected to the second superconducting device. In addition, the second connection layer and the second superconducting layer 6 can be prepared at the same time.

[0087] In the present application, the thickness of the first superconducting layer is more uniform and the roughness deviation is smaller, which can effectively ensure that the surface of the deposited material forming the barrier layer 5 is more uniform, thereby effectively improving the stability of the junction resistance.

[0088] An embodiment of the present invention further provides a quantum chip, comprising:

[0089] a first circuit element, a second circuit element;

[0090] In the Josephson junction prepared by the preparation method in the embodiment of the present application, the first superconducting layer is electrically connected to the first circuit element, and the second superconducting layer 6 is electrically connected to the second circuit element.

[0091] An embodiment of the present invention further provides a quantum chip, comprising the quantum circuit in the embodiment of the present application.

[0092] An embodiment of the present invention further provides a quantum device, comprising the above-mentioned quantum chip.

[0093] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A method for manufacturing a superconducting layer, characterized in that: The following steps are involved: Performing at least two oblique evaporation depositions on a first deposition window of a mask layer formed on a substrate to form a superconducting layer, wherein the deposition window is formed by etching or exposing and developing the mask layer; Wherein, the direction of the oblique evaporation each time is a first direction and a second direction which are selected and different; In the at least two oblique evaporations, the oblique evaporation along the first direction and the oblique evaporation along the second direction are each performed at least once, and the number of times each is performed is selected to combine to eliminate or reduce the uneven thickness of the superconducting layer caused by the oblique evaporation only from the first direction or only from the second direction.

2. The method for manufacturing a superconducting layer according to claim 1, characterized in that: The first deposition window is in the shape of an elongated strip, the first direction is from one end of the first deposition window toward the other end, and the second direction is from the other end toward the one end.

3. The method for manufacturing a superconducting layer according to claim 1 or 2, characterized in that: The deposition in the first direction is performed multiple times, and at least one deposition angle in the first direction is different from the other deposition angles.

4. The method for manufacturing a superconducting layer according to claim 3, characterized in that: The angles of the oblique evaporation in the first direction and the second direction are symmetrical, and the number of oblique evaporations is the same.

5. The method for manufacturing a superconducting layer according to claim 4, characterized in that: Oblique evaporation is performed once in both the first direction and the second direction.

6. A method for manufacturing a Josephson junction, characterized in that: The following steps are involved: A mask layer on the substrate forms a first deposition window and a second deposition window, and a first superconducting layer is prepared in the first deposition window by the method for preparing a superconducting layer according to any one of claims 1 to 5; forming a barrier layer on the first superconducting layer at the intersection of the first deposition window and the second deposition window; A second superconducting layer is deposited on the second deposition window to obtain a Josephson junction at the intersection.

7. The method for manufacturing a Josephson junction according to claim 6, characterized in that: The first deposition window and the second deposition window form an intersection, and the evaporation material covers the intersection each time oblique evaporation is performed.

8. The method for manufacturing a Josephson junction according to claim 6 or 7, characterized in that: The mask layer on the substrate forms a first deposition window, comprising: Apply two layers of photoresist evenly on the surface of the substrate to form a mask layer; Determining a first region on the mask layer for forming a first deposition window and a second region for forming a second deposition window; The mask layer in the first area is etched or exposed and developed to retain the suspended gel structure in the first area, wherein the suspended gel structure includes a left suspended gel structure extending outward from the left side wall of the second area to a set width and a right suspended gel structure extending outward from the right side wall of the second area to a set width; wherein the left suspended gel structure and the right suspended gel structure are structures in which the lower layer of photoresist on the substrate has been removed and the upper layer of photoresist on the lower layer of photoresist is retained, and are used to prevent the evaporated material from evaporating from the second deposition window onto the substrate when oblique evaporation deposition is performed on the first deposition window.

9. The method for manufacturing a Josephson junction according to claim 6 or 7, characterized in that: The step of depositing the second deposition window to form a second superconducting layer to obtain a Josephson junction at the intersection comprises: forming a second superconducting layer by depositing the second deposition window by at least two oblique evaporations or by straight evaporation to obtain a Josephson junction at the intersection; When the second deposition window is subjected to at least two oblique evaporations, the direction of each oblique evaporation is a third direction and a fourth direction that are selected and different; In the at least two oblique evaporations, the oblique evaporation along the third direction and the oblique evaporation along the fourth direction are each performed at least once, and the number of times each is performed is selected to combine to eliminate or reduce the uneven thickness of the superconducting layer caused by the oblique evaporation only from the third direction or the oblique evaporation only from the fourth direction.

10. A quantum circuit, characterized in that: It comprises a Josephson junction manufactured by the method for manufacturing a Josephson junction according to any one of claims 6 to 9.

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