Chip product preparation method and system

Abstract

The invention discloses a chip product preparation method and system, and relates to the technical field of micro-nano processing. The method comprises the following steps: preparing a bottom layer circuit on a substrate to obtain a first chip product; coating a first photoresist on the first chip product; the first photoresist at the position, corresponding to the pier of the air bridge, of the first chip product is removed, a bridge support structure at the bridge body position of the air bridge is obtained, and the bridge support structure is composed of the first photoresist; evaporating a first metal film layer on the first chip product; coating a second photoresist on the first chip product; removing the second photoresist at the target position and the first metal film layer at the target position; evaporating a second metal film layer on the first chip product; the first chip product is placed in the photoresist removing solution to be cleaned, a second chip product is obtained, and the second chip product comprises a bottom layer circuit and the air bridge composed of the second metal film layer. According to the scheme, the performance of a chip product can be improved.

Description

Technical Field

[0001] The present application relates to the field of micro-nano processing technology, and in particular to a chip product preparation method and system. Background Art

[0002] In chip manufacturing, an air bridge is a circuit structure that achieves planar circuit bridging in a three-dimensional bridge-like manner.

[0003] In related technologies, air bridge stripping technology mostly uses chemical corrosion or mechanical scraping to separate invalid bridge wires from the surface of chip products. The production machine spin-coats multiple layers of photoresist on the substrate, then uses a mask to expose the photoresist to dissolve in the developer, then forms an air bridge by evaporating tin, and finally removes the invalid bridge part by exposure and other means to achieve air bridge stripping technology.

[0004] However, in the above scheme, due to the principle of like dissolves like of photoresists, most photoresists cannot be used together, which limits the flexibility of chip manufacturing. In addition, since photoresists are prone to cross-linking reactions, the air bridge cannot be stripped cleanly, thereby affecting the connection between the air bridge and the underlying circuit, and further affecting the performance of the chip. Summary of the invention

[0005] The embodiment of the present application provides a chip product preparation method and system, which can improve the performance of the chip product. The technical solution is as follows.

[0006] In one aspect, a method for preparing a chip product is provided, the method comprising:

[0007] Preparing a bottom layer circuit on a substrate to obtain a first chip product;

[0008] Applying a first photoresist on the first chip product;

[0009] Removing the first photoresist at the bridge pier position corresponding to the air bridge on the first chip product to obtain a bridge support structure at the bridge body position of the air bridge, wherein the bridge support structure is formed by the first photoresist;

[0010] Vapor depositing a first metal film layer on the first chip product;

[0011] Applying a second photoresist on the first chip product;

[0012] removing the second photoresist at a target position and the first metal film layer at the target position; the target position includes the bridge body position and the bridge pier position;

[0013] Vapor depositing a second metal film layer on the first chip product;

[0014] The first chip product is placed in a degumming solution for cleaning to obtain a second chip product, wherein the second chip product includes the bottom layer circuit and the air bridge formed by the second metal film layer.

[0015] On the other hand, a chip product preparation system is provided, the system comprising: a coating machine, a photolithography machine, a vapor deposition machine, an etching machine, a developing machine and a degumming machine:

[0016] By means of the coating machine, the photolithography machine, the evaporation machine, the etching machine, the developing machine and the degumming machine, a bottom layer circuit is prepared on a substrate to obtain a first chip product;

[0017] Applying a first photoresist on the first chip product by the coating machine;

[0018] Using the photolithography machine and the developer, removing the first photoresist at the bridge pier position corresponding to the air bridge on the first chip product, and obtaining a bridge support structure at the bridge body position of the air bridge, wherein the bridge support structure is composed of the first photoresist;

[0019] Using the evaporation machine, evaporating a first metal film layer on the first chip product;

[0020] Applying a second photoresist on the first chip product by the coating machine;

[0021] Using the photolithography machine and the developer, removing the second photoresist at the target position and the first metal film layer at the target position; the target position includes the bridge body position and the bridge pier position;

[0022] Using the evaporator, ion milling and etching are performed on the first chip product to remove the natural oxide layer at the bridge pier position;

[0023] In-situ evaporating a second metal film layer on the first chip product by the evaporation machine;

[0024] The first chip product is placed in a degumming liquid for cleaning by the degumming machine to obtain a second chip product, wherein the second chip product includes the bottom circuit and the air bridge formed by the second metal film layer.

[0025] In a possible implementation, the photolithography machine and the developer are used to perform exposure and development processing on the first chip product after the second photoresist is coated, so as to remove the second photoresist at the target position;

[0026] The etcher is used to perform etching processing on the first chip product after removing the second photoresist at the target position, so as to remove the first metal film layer at the target position.

[0027] In a possible implementation, the etcher is used to perform wet etching on the first chip product using an etching solution corresponding to the first metal film layer to remove the first metal film layer at the target position.

[0028] In a possible implementation manner, the first metal film layer is made of metal aluminum or metal chromium.

[0029] In a possible implementation, the coating machine is used to coat the second photoresist on the first chip product, including: coating the first positive photoresist on the first chip product and baking it;

[0030] The coating machine is used to coat the second positive photoresist on the first chip product after the first positive photoresist is coated and bake the first chip product;

[0031] The photolithography machine and the developer are used to perform exposure and development processing on the first chip product after the second photoresist is applied, so as to remove the second photoresist at the target position, and include:

[0032] The photolithography machine performs exposure processing on the second photoresist at the target position;

[0033] The developer develops the first chip product using a developer corresponding to the second positive photoresist to remove the first positive photoresist and the second positive photoresist at the target position and form an undercut structure at the edge of the remaining first positive photoresist.

[0034] In another possible implementation manner, the first metal film layer and the second metal film layer may be evaporated by different evaporators.

[0035] In a possible implementation, the thickness of the first positive photoresist is not less than the thickness of the second metal film layer, and the thickness of the second positive photoresist is not less than the thickness of the first positive photoresist.

[0036] In a possible implementation, the second photoresist is a negative photoresist;

[0037] The photolithography machine and the developer are used to perform exposure and development processing on the first chip product after the second photoresist is applied, so as to remove the second photoresist at the target position, and include:

[0038] The photolithography machine is used to perform exposure processing on the second photoresist outside the target position;

[0039] The developer is used to develop the first chip product using a developer corresponding to the negative photoresist to remove the second photoresist at the target position and form an undercut structure composed of the remaining second photoresist.

[0040] In a possible implementation manner, the thickness of the negative photoresist is not less than the thickness of the second metal film layer.

[0041] In a possible implementation manner, the first metal film layer remaining after the etching process forms an undercut structure at the target position.

[0042] In a possible implementation manner, the thickness of the first metal film layer is not less than 25 nm.

[0043] In a possible implementation, the evaporator is used to perform ion milling etching on the first chip product to remove the natural oxide layer at the bridge pier position.

[0044] In a possible implementation, the evaporator is used to perform in-situ evaporation of the second metal film layer on the first chip product.

[0045] In a possible implementation, the debonding machine is used to debond the first chip product and peel off the second metal film layer.

[0046] In a possible implementation, the etcher is used to immerse the first chip product in an aluminum etching solution to obtain the second chip product.

[0047] In a possible implementation, the air bridge is a fully-inclusive air bridge or a discrete air bridge.

[0048] In a possible implementation manner, the second chip product is used to prepare a superconducting quantum chip; or, the second chip product is a superconducting quantum chip.

[0049] The beneficial effects brought by the technical solution provided by the embodiment of the present application include at least:

[0050] When preparing the air bridge, firstly, the first photoresist is coated on the first chip product, and the first photoresist is subjected to a photolithography reflow operation to obtain a bridge support structure at the bridge body position of the air bridge. On this basis, the first chip product is evaporated to obtain a first metal film layer, and the second photoresist is continuously coated on the first metal film layer to form an undercut structure on the second photoresist so that the subsequent stripping of the second metal film layer is more convenient. Since the first metal film layer has a specific etching solution, the subsequent etching operation is convenient and does not damage the photoresist. Since the first metal film layer is between the two layers of photoresist, the cross-linking reaction of the two layers of photoresist due to the principle of similar dissolution is prevented. Since the first photoresist will undergo the exposure and development process again with the second photoresist, the formed bridge support structure is protected from the influence of subsequent exposure under the protection of the first metal film layer, and the bridge support is prevented from being dissolved by the developer during the second development, thereby improving the quality of chip product manufacturing and thus improving the performance of the chip product.

[0051] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0053] Figure 1 is a schematic diagram of an air bridge shown;

[0054] Figure 2 is a structural diagram of a discrete air bridge and a fully enclosed air bridge shown in an exemplary embodiment;

[0055] Figure 3 This is a process flow chart of preparing aluminum air bridge by etching method, which is shown as an exemplary embodiment;

[0056] Figure 4 is a process flow chart of preparing aluminum air bridge by stripping method, showing an exemplary embodiment;

[0057] Figure 5 It is a schematic cross-sectional view of an exemplary embodiment showing the preparation of an air bridge by etching method before debonding;

[0058] Figure 6 It is a schematic diagram showing an exemplary embodiment of preparing an air bridge by etching, in which the denatured photoresist at the edge of the bridge pier is difficult to remove;

[0059] Figure 7 is a method flow chart of a chip product preparation method shown in an exemplary embodiment of the present application;

[0060] Figure 8is a method flow chart of a chip product preparation method shown in an exemplary embodiment of the present application;

[0061] Fig. 9 is a method flow chart of a chip product preparation method shown in an exemplary embodiment of the present application;

[0062] Fig.10 is a method flow chart of a chip product preparation method shown in an exemplary embodiment of the present application;

[0063] Fig.11 is a method flow chart of a chip product preparation method shown in an exemplary embodiment of the present application;

[0064] Fig.12 is a method flow chart of a chip product preparation method shown in an exemplary embodiment of the present application;

[0065] Fig.13 yes Fig.12 A schematic diagram of a substrate with a coplanar waveguide according to the illustrated embodiment;

[0066] Fig.14 yes Fig.12 A schematic diagram of spin coating a first photoresist according to the embodiment shown;

[0067] Fig.15 yes Fig.12 A schematic diagram of a photolithography bridge pier area involved in the illustrated embodiment;

[0068] Fig.16 yes Fig.12 The schematic diagram of the reflux involved in the illustrated embodiment;

[0069] Fig.17 yes Fig.12 A schematic diagram of a vapor-deposited sacrificial layer according to the embodiment shown;

[0070] Fig.18 yes Fig.12 The sacrificial layer involved in the embodiment shown is torn during the subsequent high-speed rotation of the glue coating (left), and the bridge support is heated during the subsequent glue coating, so the sacrificial layer cannot effectively maintain the bridge support structure, and then deforms (right);

[0071] Fig.19 yes Fig.12 A schematic diagram of spin coating a second photoresist (positive photoresist combination) according to the embodiment shown;

[0072] Fig. 20 yes Fig.12 Schematic diagram of spin coating a second photoresist (negative photoresist) according to the embodiment shown;

[0073] Fig.21 yes Fig.12Schematic diagram of a photolithography air bridge (positive resist combination) involved in the illustrated embodiment;

[0074] Fig. 22 yes Fig.12 A schematic diagram of a photolithography air bridge (negative photoresist) according to the embodiment shown;

[0075] Fig.23 yes Fig.12 Schematic diagram of ion milling (positive resist combination) involved in the illustrated embodiment;

[0076] Fig.24 yes Fig.12 Schematic diagram of ion milling (negative photoresist) involved in the illustrated embodiment;

[0077] Fig.25 yes Fig.12 Schematic diagram of the evaporated air bridge superconducting film (positive resist combination) involved in the illustrated embodiment;

[0078] Fig.26 yes Fig.12 Schematic diagram of the evaporated air bridge superconducting film (negative resist) involved in the illustrated embodiment;

[0079] Fig. 27 yes Fig.12 The peeling schematic diagram of the embodiment shown;

[0080] Fig.28 yes Fig.12 A schematic diagram of the steps for preparing the all-inclusive air bridge apertures involved in the illustrated embodiment;

[0081] Fig.29 yes Fig.12 Schematic diagram of a discrete air bridge prepared in accordance with the illustrated embodiment;

[0082] Fig.30 yes Fig.12 A schematic diagram of a fully enclosed air bridge prepared in accordance with the embodiment shown;

[0083] Fig.31 yes Fig.12 The illustrated embodiment is a schematic diagram of the entire process of a process in which the second photoresist is a positive photoresist combination as an example;

[0084] Fig.32 is a schematic diagram of a chip product preparation system shown in an exemplary embodiment of the present application;

[0085] Fig.33 It is a schematic diagram of an application scenario of a solution provided by an embodiment of the present application. DETAILED DESCRIPTION

[0086] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0087] Airbridge pier: The area reserved on the underlying circuit structure for the air bridge to contact the underlying circuit.

[0088] Airbridge scaffold: It is located between the air bridge and the underlying circuit. It is used to support the bridge structure before the air bridge is formed. After the air bridge is completed, the airbridge scaffold is removed by the degumming liquid.

[0089] Lithography & development: A micro-nano processing technology that mainly involves ultraviolet lithography, which is to apply photoresist on the surface of the substrate sample, and then irradiate ultraviolet light through the mask to the substrate surface, use photochemical reaction to change the properties of the photoresist exposed to light, and then dissolve the area that reacts with light into a specific solution to achieve the purpose of making a specific pattern on the substrate.

[0090] Etching: A micromachining process that uses dry (other) and wet (liquid) methods to corrode metal or other materials to form the required structure.

[0091] Lift-off technology refers to the process in which, after a substrate is coated with photoresist (photoresist), exposed and developed, a photoresist film with a certain pattern is used as a mask to deposit the required materials, such as metals, through evaporation and other methods. Then, while removing the photoresist, the non-required materials on the film are stripped off, leaving only the material structure with the original pattern on the substrate.

[0092] Sacrificial layer: In micro-nano processing, the desired structure is prepared on top of a thin film, and then the film is removed to retain the prepared structure.

[0093] Airbridge: A device in a superconducting quantum chip, similar to an arch bridge structure, spanning an infinite ground plane on both sides of a coplanar waveguide.

[0094] Coplanar waveguide: A device in a superconducting quantum chip consisting of a central conductor and infinite ground planes on both sides, used to transmit microwave signals.

[0095] Discrete airbridge: A common airbridge structure in which the span and width of the bridge are of the same order of magnitude.

[0096] Full cap airbridge: The airbridge has a continuous bridge body, and the span of the bridge body is much smaller than the width of the airbridge.

[0097] Superconductor: Below a certain temperature, the resistance of the material suddenly drops to 0 and it has complete anti-magnetism.

[0098] Superconducting quantum chip: A chip used for superconducting quantum computing, including coplanar waveguides, air bridges, superconducting quantum bits and other devices.

[0099] In situ: Multi-step processes are performed in a single vacuum chamber or in multiple interconnected vacuum chambers without exposure to the atmospheric environment.

[0100] Ion milling: An ion source is used to generate Ar ions, which bombard the metal surface in a vacuum to remove the natural oxide layer on the metal surface.

[0101] Undercut: A structure in which the opening on the upper surface is smaller than the opening at the bottom of the photoresist after development.

[0102] Please refer to Figure 1 , Figure 1 A side view of an air bridge is shown.

[0103] Superconducting quantum chips rely on coplanar waveguides to transmit microwave signals. As the complexity of the chip increases, the coplanar waveguides become more and more dense. When the coplanar waveguides are dense to a certain extent, microwave signals will crosstalk with each other, that is, the microwave signal originally applied to one coplanar waveguide can be observed in another coplanar waveguide. This signal crosstalk is not conducive to the regulation of superconducting quantum chips. One way to solve the signal crosstalk is to shield the microwave signal on the coplanar waveguide through an air bridge structure. Generally, the air bridge structure connects the infinite ground planes on both sides of the coplanar waveguide so that the ground planes on both sides are at the same electric potential. In addition, the air bridge can also be used as a cross-line to connect the central conductor of two separate coplanar waveguides, so that microwaves are transmitted through the air bridge, making the wiring of superconducting quantum chips more flexible.

[0104] At present, the materials used for superconducting quantum chip air bridges include superconducting metals such as aluminum (Al), tantalum (Ta), niobium (Nb), and titanium nitride (TiN). Superconducting Al film is the most widely used air bridge material because it is easy to etch. According to the ratio of the span and width of the air bridge body (the distance between the piers is called the span, and the size of the bridge body in the perpendicular direction is called the width), the air bridge can be simply divided into two types: a stand-alone air bridge and a fully enclosed air bridge, such as Figure 2 Furthermore, holes can be opened on the bridge body of the all-inclusive air bridge. The small holes on the bridge body are conducive to the flow inside and outside the air bridge, so that the glue removal is cleaner, and the bridge holes also make the structure of the air bridge more stable.

[0105] Please refer to Figure 1 Before the air bridge is finally stripped, the bottom of the bridge is filled with photoresist, which will be removed in the end. If there are no openings on the bridge body of the fully enclosed air bridge, the photoresist can only flow out through the two ends of the bridge. If there are openings (like Figure 2 As shown in the figure), the degumming liquid can bring out the photoresist under the bridge through these small holes. If there are no holes in the bridge body, the fully covered bridge can only flow liquid through the openings at both ends of the bridge. Megasonic cleaning (high-speed flowing liquid) is required for degumming. The pressure difference caused by the liquid impacting the bridge body can easily cause the bridge to deform. If the bridge body has holes, high-speed liquid can enter and exit the bridge body through the holes, so that the pressure difference on both sides of the bridge can be alleviated and the bridge is not easily damaged.

[0106] The preparation process of air bridge can be divided into two categories, one is etching method and the other is stripping method. Since Al is the most widely used air bridge material, Al is easier to etch with etching solution, so etching method is the most widely used method to prepare air bridge.

[0107] The etching method for preparing air bridges in the related technical solutions has the following disadvantages:

[0108] 1. There are many restrictions on the materials of air bridges. Usually, the etching of Al is relatively easy to achieve, and it can be etched directly using Al etching solution. However, for other common superconducting quantum chip preparation materials, such as Ta, Nb, TiN, etc., special etching solutions are required to etch the metal, and the etching solution often damages the photoresist. Instead, dry etching is often used to etch these superconducting metal materials, but dry etching requires additional etching equipment and special process gases, and the corresponding etching process needs to be explored. Existing data show that superconducting quantum chips prepared by Ta have better performance than those prepared by Al, so the Al etching method for preparing air bridges can no longer meet the needs of diversified air bridge preparation.

[0109] 2. Air bridge debonding is difficult. Usually, before evaporating the air bridge superconducting metal, ion milling is performed in situ to remove the natural oxide layer on the coplanar waveguide, so that a good superconducting contact is formed between the coplanar waveguide and the air bridge. However, during the ion milling process, the photoresist will also be denatured by Ar ion bombardment, and the denatured photoresist is insoluble in the debonding solution. The cross-sectional schematic diagram before the last step of debonding in this scheme is shown in the figure. Figure 5 As shown in FIG. 1 , when etching the air bridge Al, in order to prevent the underlying coplanar waveguide where the bridge pier is located from being etched, a portion of the air bridge Al will be retained outside the bridge pier, which will cause the bridge pier to adhere to the denatured photoresist (such as Figure 5 The circled part) is not easy to remove during the stripping process. Figure 6 shown.

[0110] The air bridge preparation method of the stripping method in the related technical solution has the following disadvantages:

[0111] 1. There are strong restrictions on photoresists. The idea of ​​preparing air bridges by the stripping method is to use positive photoresists to form bridge supports, and then use negative photoresists to define the shape of the bridge. This requires that positive photoresists and negative photoresists are immiscible. However, for most photoresists, due to their similar compositions, many photoresists cannot be used together according to the principle of like dissolves like. In an existing scheme, PMGI SF15 (non-photosensitive photoresist) can be used to be immiscible with SU-8 photoresist, and PMGI SF15 can be formed into an arch shape through high-temperature reflow, so that an air bridge can be prepared. However, PMGI SF15 will continue to dissolve in the developer, and once the SU8 photoresist undergoes a cross-linking reaction, it is difficult to dissolve in the stripping solution. These all impose strong restrictions on the process. This method also cannot use positive photoresists or negative photoresists at the same time to prepare air bridges.

[0112] 2. It is inconvenient to measure the intermediate process. After the bridge support structure is formed, it is usually necessary to measure the structure with a step profiler and observe the morphology with a microscope. Usually, the light source of these devices does not have a yellow light function. If a positive photoresist is used to prepare the bridge support, the shape of the bridge support can only be observed after the negative photoresist is exposed. Otherwise, the bridge support part will be exposed in advance, and during the negative photoresist development process, the bridge support will also be developed, thereby losing the shape of the bridge support and causing process failure. If the shape of the bridge support is observed after the negative photoresist is developed, the intermediate process of the process cannot be observed.

[0113] In response to the above problems, the subsequent embodiments of the present application propose an optimized air bridge structure that can not only avoid the problem of air bridge material limitation, but also solve the problem of difficulty in degumming, and can also facilitate the detection of the intermediate process and facilitate timely measurement after the bridge support is formed.

[0114] Please refer to Figure 7, which shows a method flow chart of a chip product preparation method shown in an exemplary embodiment of the present application. Figure 7 As shown, the method may include the following steps:

[0115] Step 701, prepare the bottom layer circuit on the substrate to obtain the first chip product.

[0116] The first chip product may include a substrate and an underlying circuit, wherein the underlying circuit may be prepared by a photolithography-development-deposition method.

[0117] Alternatively, the bottom layer circuit may also be prepared by a coating-photolithography-etching method.

[0118] Alternatively, the above-mentioned bottom layer circuit can also be prepared by nanoimprinting.

[0119] The first chip product may be a semi-finished product in the process of preparing the final finished chip.

[0120] In some embodiments, the etching method (i.e., the preparation method of "coating-photolithography-etching") has a more precise line width compared to the stripping method (i.e., the preparation method of "photolithography-development-deposition" mentioned above), which is required by the underlying circuit, and the air bridge does not have high requirements on the line width.

[0121] Step 702: coating a first photoresist on a first chip product.

[0122] In the embodiment of the present application, a layer of first photoresist can be coated on the first chip product by a coating machine.

[0123] Step 703: remove the first photoresist at the bridge pier position corresponding to the air bridge on the first chip product to obtain the bridge support structure at the bridge body position of the air bridge, wherein the bridge support structure is formed by the first photoresist.

[0124] The pier positions of the above-mentioned air bridge structure may be pre-defined by the designer and located in a designated area in the underlying circuit.

[0125] Step 704: evaporate a first metal film layer on the first chip product.

[0126] The material of the first metal film layer may be aluminum or chromium, which is a material with a specific etching solution, and the thickness of the first metal film layer is generally between a few nanometers and tens of nanometers.

[0127] In some embodiments, the thickness of the first metal film layer is not less than 25 nm.

[0128] Optionally, the thickness of the first metal film layer may be 28 nanometers.

[0129] In an embodiment of the present application, the thickness of the first metal film layer is not less than 25 nanometers. Since photoresist will be spin-coated on the first metal film layer later, the substrate will undergo high-speed rotation and baking again, and the thinner metal film layer will be torn under high-speed rotation; after spin-coating the photoresist, it will be baked in order to solidify the photoresist. Baking again will also increase the fluidity of the first photoresist. A metal film that is too thin cannot wrap the bridge support structure well and may also deform again.

[0130] In the embodiment of the present application, the first metal film layer can be evaporated on the first chip product by using an evaporation machine.

[0131] Step 705: coating a second photoresist on the first chip product.

[0132] In the embodiment of the present application, a layer of second photoresist can be coated on the first chip product by a coating machine.

[0133] Step 706, removing the second photoresist at the target position and the first metal film layer at the target position; the target position includes the bridge body position and the bridge pier position.

[0134] The pier positions of the above-mentioned air bridge structure may be pre-defined by the designer and located in a designated area in the underlying circuit.

[0135] Step 707: evaporate a second metal film layer on the first chip product.

[0136] Before evaporating the second metal film layer on the first chip product, the first chip product is also ion-milled to remove the natural oxide layer at the bridge pier position.

[0137] To perform ion milling operations, you first need to select appropriate operating equipment and ion source, and ensure that the operating equipment and ion source are in good working condition. Then clean and prepare the chip product to be processed, ensure that its surface is clean, and then adjust the parameters of the ion source as needed, such as ion energy, beam density and processing time, etc. These parameters will affect the processing effect and speed. Place the chip product under the ion beam, ensure that there is enough distance between it and the ion source, use a sample holder or clamp to fix the sample in position, and finally turn on the ion source to start releasing the ion beam. The ion beam will hit the sample surface, sputter or evaporate the surface material, thereby achieving the processing effect.

[0138] In some embodiments, a Kaufman ion source can be used to ionize and accelerate argon gas using thermal emission electrons, and the argon ions bombard the sample surface to achieve an etching effect. In one embodiment, the argon gas flow rate is set to 6 sccm, the ion beam voltage is set to 600V, the ion beam current is set to 35mA, the acceleration voltage is set to 120V, and the neutralization voltage is set to 40V.

[0139] In the embodiments of the present application, the natural oxide layer of the chip product is removed by ion milling operation, forming a good superconducting contact surface on the underlying circuit and the air bridge, so that the performance of the chip product can be better exerted.

[0140] Step 708: Place the first chip product in a degumming solution for cleaning to obtain a second chip product, wherein the second chip product includes the bottom circuit and the air bridge formed by the second metal film layer.

[0141] In the embodiment of the present application, the first chip product can be cleaned by a degumming machine to obtain the second chip product.

[0142] In one possible implementation, when the material of the coplanar waveguide layer of the bottom circuit of the first chip product is not aluminum, the material of the first metal film layer is tantalum, niobium or titanium nitride (non-aluminum), the material of the second metal film layer is tantalum, niobium or titanium nitride, and the first metal film layer is aluminum. The first chip product is placed in a degumming solution for cleaning to obtain a second chip product. The first chip product can be placed in a degumming solution for cleaning and then immersed in an aluminum etching solution to obtain the second chip product.

[0143] The first chip product is placed in a degumming solution to remove the photoresist on the substrate, and the metal film layer thereon is also peeled off together, leaving only the second metal film layer in the shape of an air bridge. Since some residues may be left on the surface of the first chip product during the peeling process, these residues will affect the subsequent process steps. Therefore, it is necessary to clean the surface by immersing it in an aluminum etching solution to obtain the second chip product.

[0144] In the embodiment of the present application, the aluminum etching solution is a mixture of phosphoric acid, nitric acid and acetic acid, which can effectively select metal aluminum for etching without damaging metals such as tantalum, niobium or titanium nitride, and has high selectivity. In the case where the first metal film layer is aluminum, there may be a small amount of aluminum chips during the stripping process. After degumming, soaking in the aluminum etching solution can effectively remove the residual aluminum chips without damaging other structures. In the embodiment of the present application, the above-mentioned air bridge is a fully enclosed air bridge or a discrete air bridge.

[0145] In an embodiment of the present application, the second chip product is used to prepare a superconducting quantum chip; or, the second chip product is a superconducting quantum chip.

[0146] In summary, the scheme shown in the embodiment of the present application, when preparing the air bridge, firstly, the first photoresist is coated on the first chip product, and the first photoresist is subjected to a photolithography reflow operation to obtain a bridge support structure at the bridge body position of the air bridge, and on this basis, the first chip product is subjected to vapor deposition to obtain a first metal film layer, and the second photoresist is continuously coated on the first metal film layer, so that the subsequent stripping of the second metal film layer is more convenient. Since the first metal film layer has a specific etching solution, the subsequent etching operation is convenient and does not damage the photoresist. Since the first metal film layer is between the two layers of photoresist, the cross-linking reaction of the two layers of photoresist due to the principle of like dissolves like is prevented. Since the first photoresist will undergo the exposure and development process again with the second photoresist, the formed bridge support structure is protected from the influence of subsequent exposure under the protection of the first metal film layer, and the bridge support is prevented from being dissolved by the developer during the second development, thereby improving the quality of chip product manufacturing and thus improving the performance of the chip product.

[0147] Based on the above Figure 7 For the examples shown, please refer to Figure 8 , which shows a method flow chart of a chip product preparation method shown in an exemplary embodiment of the present application. Figure 8 As shown, the chip product preparation method may include the following steps:

[0148] Step 706a: performing exposure and development processing on the first chip product after coating the second photoresist to remove the second photoresist at the target position.

[0149] First, place the chip product on an exposure device, usually using an ultraviolet light source. The exposure device can project the required pattern of the second photoresist onto the first chip product through a mask or template, and then use a chemical solution, i.e., a developer, to dissolve the photoresist at the target position and retain the required pattern.

[0150] Step 706b: After removing the second photoresist at the target position, the first chip product is etched to remove the first metal film layer at the target position. Add etching liquid into the etcher, adjust the equipment parameters, and put the first chip product into the etcher for etching. Common etching liquids include wet etching liquid and dry etching liquid. Wet etching liquid refers to the use of liquid solution, such as acidic or alkaline solution, to dissolve or corrode materials during the etching process. Dry etching liquid refers to the use of gas or plasma to corrode materials during the etching process instead of using liquid solution.

[0151] The first metal film layer and the second photoresist remaining after the etching process form an undercut structure at the target position.

[0152] The above-mentioned undercut structure is more conducive to the stripping of the photoresist, thereby improving the quality of air bridge preparation and enhancing the performance of chip products.

[0153] In a possible implementation, the first metal film layer can be etched by a developer, where the etching solution can be a dedicated metal etching solution or a developer.

[0154] For example, for metallic aluminum, aluminum etching solution can be used.

[0155] In some embodiments, if the first metal film layer is aluminum, in the above-mentioned development process, by controlling the development time, since aluminum also reacts with the alkaline developer, the second photoresist and the first metal film layer can be removed simultaneously. By appropriately controlling the process operation, the etching step of this scheme can also be omitted.

[0156] To summarize, in the embodiment of the present application, etching is performed on the second photoresist at the target removal position, so that the first metal film layer is removed more cleanly, the first photoresist at the target position is better retained, the structural forming of the subsequently manufactured air bridge is more perfect, and the overall stability of the air bridge is improved, which helps to ensure that the air bridge will not deform or collapse during use, thereby improving safety and thus improving the performance of the chip product.

[0157] In a possible implementation, the second photoresist includes a first positive photoresist and a second positive photoresist; the first positive photoresist is a non-photosensitive positive photoresist, and the second positive photoresist is a photosensitive positive photoresist, please refer to Fig. 9 ,based on Figure 8 , which shows a method flow chart of a chip product preparation method shown in an exemplary embodiment of the present application. Step 705 of applying a second photoresist on the first chip product includes steps 705a and 705b, and step 706a of performing exposure and development treatment on the first chip product after applying the second photoresist to remove the second photoresist at the target position includes steps 706a1 and 706a2. Fig. 9 As shown, the chip product preparation method may include the following steps:

[0158] Step 705a: coating the first positive photoresist on the first chip product and baking it.

[0159] In some embodiments, the coating operation is performed by a glue coating machine, and the baking operation can be performed by baking equipment, such as a hot plate, a hot plate furnace, and a hot plate oven.

[0160] Step 705b: Apply a second positive photoresist on the first chip product after the first positive photoresist is applied and bake.

[0161] Step 706a1: Expose the second photoresist at the target position.

[0162] In the embodiment of the present application, since the second photoresist is a photosensitive positive photoresist, the second photoresist at the target position can be exposed using an ultraviolet exposure machine or a laser direct writing device, and the photoresist in the exposed area will be removed after development.

[0163] Step 706a2: Develop the first chip product with a developer corresponding to the second positive photoresist to remove the first positive photoresist and the second positive photoresist at the target position, and form an undercut structure at the edge position of the remaining first positive photoresist.

[0164] In an embodiment of the present application, after removing the first positive photoresist and the second positive photoresist at the target position, a large inverted trapezoidal structure is formed, and a small undercut structure is formed at the edge of the remaining first positive photoresist. The undercut structure makes it easier to strip the photoresist.

[0165] In an embodiment of the present application, the first positive photoresist has a relatively high dissolution rate in the developer and is mainly used to form a good undercut structure. Its thickness is greater than that of the second metal film layer to facilitate stripping, and at the same time, its thickness is less than that of the second positive photoresist to prevent stripping of the second positive photoresist. The second photoresist is usually thicker, which is not easily stripped by the first positive photoresist on the one hand, and can better strip the second metal film layer on the other hand.

[0166] Optionally, the thickness of the first positive photoresist is between 0.5 microns and 1.5 microns, the thickness of the second positive photoresist is above 3 microns, the thickness of the first positive photoresist is not less than the thickness of the second metal film layer, and the thickness of the second positive photoresist is not less than the thickness of the first positive photoresist. For example, the thickness of the first positive photoresist is 0.5um, and the thickness of the second positive photoresist is 3.3um.

[0167] In the embodiment of the present application, the use of photoresists of different thicknesses can make the photolithography pattern easier to align and reduce the alignment error. When the first positive photoresist is thinner, it is easier to achieve high-resolution exposure and obtain a more detailed pattern.

[0168] In summary, in the embodiment of the present application, the photoresist in the exposed area is removed through the positive photoresist combination to form an inverted trapezoidal bottom cut structure, which is more conducive to the stripping of the air bridge, thereby improving the quality of the chip product.

[0169] In another possible implementation, the second photoresist is a negative photoresist, and the first chip product is exposed and developed after the second photoresist is coated to remove the second photoresist at the target position. Fig.10 ,based on Figure 8 , which shows a method flow chart of a chip product preparation method shown in an exemplary embodiment of the present application. Fig.10 As shown, the chip product preparation method may include the following steps:

[0170] Step 706a3: performing exposure processing on the second photoresist outside the target position.

[0171] In some embodiments, the second photoresist is a negative photoresist, that is, the photoresist in the exposed area will be retained, and a UV exposure machine can be used to expose the area outside the bridge body. The photoresist in the area where the air bridge is located will be dissolved, thereby forming an air bridge shape with an undercut structure.

[0172] Step 706a4: Develop the first chip product with a developer corresponding to the negative photoresist to remove the second photoresist at the target position, thereby forming an undercut structure composed of the remaining second photoresist.

[0173] In an embodiment of the present application, the thickness of the negative photoresist is not less than the thickness of the second metal film layer. For example, the thickness of the second metal film layer is 3 microns, and the optional thickness of the negative photoresist can be more than 3 microns. The thickness of the negative photoresist can be 4um.

[0174] In summary, in the embodiment of the present application, a single layer of negative photoresist is used to remove the photoresist in the unexposed area to form an inverted trapezoidal undercut structure, which is more conducive to the stripping of the air bridge, thereby improving the quality of the chip product.

[0175] Based on the above Figure 8 For the examples shown, please refer to Fig.11 , which shows a method flow chart of a chip product preparation method shown in an exemplary embodiment of the present application. Fig.11 As shown, the chip product preparation method may include the following steps:

[0176] Step 706b1: wet-etching the first chip product using an etching solution corresponding to the first metal film layer to remove the first metal film layer at a target position.

[0177] The first metal film layer is converted into a liquid compound by using a chemical solution, namely an etching solution, and the first metal film layer is removed. The etching solution used must be an etching solution corresponding to the material of the first metal film layer.

[0178] In some embodiments, the material of the first metal film layer is metal aluminum or metal chromium, so the required etching solution must be able to dissolve metal aluminum or metal chromium.

[0179] The first metal layer can effectively isolate the photoresist and can be easily removed in subsequent processes. Metal aluminum and metal chromium are materials widely used in micro-machining.

[0180] In summary, the solution shown in the embodiment of the present application removes the first metal film layer, and the removal of the metal film layer facilitates the subsequent preparation of the air bridge.

[0181] In one embodiment, the solution shown in the above embodiment of the present application can be applied to the preparation of superconducting quantum chips.

[0182] From a technical perspective, the flow chart of this solution is as follows Fig.12 shown.

[0183] Step 1: Prepare a substrate with a coplanar waveguide.

[0184] The substrate material can be a sapphire substrate or a high-resistance silicon substrate. The thickness of the coplanar waveguide superconducting film is between 100nm and 200nm. The coplanar waveguide material can be a superconducting metal such as Al, Ta, Nb, TiN, etc. The shape of the coplanar waveguide is defined by the photolithography and etching process. Most superconducting materials will naturally form an oxide layer in the air, such as Fig.13 Shown is a substrate with a coplanar waveguide.

[0185] Step 2, spin coating a first photoresist on the substrate.

[0186] The photoresist can be a positive photoresist or a negative photoresist. The optional positive photoresists include SPR220 or S1813, which require the photoresist to have a reflow property to form an arch bridge structure. For SPR220 photoresist, a photoresist with a thickness of 3.3um can be spin-coated on the substrate at a speed of 3000rpm. The structure after spin coating is as follows Fig.14 A first photoresist is shown being spin coated.

[0187] Step 3, photolithography of the bridge pier area.

[0188] The first photoresist can be exposed using an ultraviolet exposure machine or a laser direct writing device. If the first photoresist is a positive photoresist, the exposure area corresponds to the area where the bridge pier is located; if the first photoresist is a negative photoresist, the exposure area corresponds to the area outside the bridge pier. After development, the photoresist at the location of the bridge pier is removed. Fig.15 Taking positive photoresist SPR220 as an example, the exposed bridge pier area and the structure after development are shown. 2 Dose exposure SPR220 photoresist, developed with MF319 developer for 50s Fig.15 structure.

[0189] Step 4, reflux.

[0190] The above substrate is placed on a heating plate and heated at high temperature. Since the first photoresist has a reflow property, the heated photoresist naturally flows to form an arched bridge structure. One embodiment is to place the substrate completed in step 3 on a 140°C hot plate and heat for 3 minutes to form a structure such as Fig.16 shown.

[0191] Step 5: evaporate a sacrificial layer.

[0192] The above substrate is placed in a vacuum coating device to evaporate the sacrificial layer. The sacrificial layer material can be selected from Al, Cr, etc., because Al and Cr have specific etching solutions, which facilitates the subsequent etching of the sacrificial layer without damaging the photoresist. The structure of the sacrificial layer after evaporation is as follows Fig.17 One embodiment is to place the above substrate in an electron beam evaporation coating device to evaporate 25nm Al.

[0193] The thickness of the sacrificial layer should not be too thin. Since the second photoresist will be spin-coated on the sacrificial layer later, the substrate will experience high-speed rotation and baking again. The thinner sacrificial layer will tear under high-speed rotation; baking again will also increase the fluidity of the first photoresist. A sacrificial layer that is too thin cannot wrap the bridge support structure well and may also deform again, such as Fig.18 The sacrificial layer shown is torn during the subsequent high-speed rotation of the glue coating (left). During the subsequent glue coating, the bridge support is heated and the sacrificial layer cannot effectively maintain the bridge support structure, thereby causing deformation (right).

[0194] There are several reasons why a sacrificial layer needs to be evaporated before the second photoresist is spin-coated. On the one hand, due to the similar properties of photoresists, many photoresists are mutually soluble according to the principle of like dissolves like. The purpose of the first photoresist is to form an arched bridge structure, and the purpose of the second photoresist is to form an undercut structure in the shape of an air bridge. The two should not interfere with each other. In the experiment, the author found that the reflowed SPR220 photoresist is mutually soluble with the commonly used LOR10B, PMGI SF series, nLof2070, PMMA A4, AZ5214 and other photoresists. If the second photoresist is directly spin-coated on it, the bridge structure formed above will be destroyed (in an existing stripping method, the process can be successfully carried out by using PMGI SF15 and SU-8 that are not miscible, but there are many restrictions on photoresists, and SU-8 itself also has problems with degumming and cracking). On the other hand, since the first photoresist will undergo the exposure and development process again with the second photoresist, the formed bridge support structure should be protected from the influence of subsequent exposure, otherwise the bridge support will continue to be dissolved by the developer during the second development. Consider the following situation: the first photoresist uses a positive photoresist, and the second photoresist also uses a positive photoresist. If you want to expose the air bridge structure on the second photoresist, the second exposure needs to expose the area where the bridge support is located again. In this way, the prepared bridge support structure will most likely be developed away during development. Adding a sacrificial layer can also play a role in shading, so that the prepared bridge support structure can be protected from the influence of the second exposure, and the prepared bridge support structure can also be exposed to a white light environment for process measurement, so that the process conditions of each step can be detected.

[0195] Step 6, spin-coat a second photoresist.

[0196] The second photoresist can be a positive resist combination or a negative resist. The ultimate goal is to form a good undercut structure. The following discusses the different situations.

[0197] Step 6-1, the second photoresist to be spin-coated is a positive photoresist combination. First, a layer of non-photosensitive photoresist is spin-coated on the above substrate. The optional photoresists include PMGI SF3, PMGI SF6 or LOR 10B. Non-photosensitive photoresists are not affected by exposure, but dissolve in developer. The dissolution rate can be adjusted by baking temperature. Generally, the higher the baking temperature, the slower the dissolution rate. Then, a layer of positive photoresist is spin-coated on it. Many positive photoresists can be used in conjunction with PMGI or LOR series photoresists for positive photoresist stripping processes, such as SPR220, S1805, S1813, etc. A set of embodiments is provided below. First, a PMGI SF3 photoresist with a thickness of about 0.5 μm is spin-coated on the above substrate multiple times at a rotation speed of 1000 rpm, and baked on a hot plate at 110° C. for 60 seconds. Then, a layer of SPR220 photoresist with a thickness of about 3.3 μm is spin-coated on the substrate at a rotation speed of 3000 rpm, and baked on a hot plate at 110° C. for 60 seconds to form a Fig.19 The double-layer glue structure shown.

[0198] Step 6-2, the second photoresist to be spin-coated is a negative photoresist. The thickness of the negative photoresist is required to be greater than the thickness of the evaporated air bridge material. The optional photoresists include nLof2070, AZ5214 (as negative photoresist), E3510, etc. One embodiment is to spin-coat the nLof2070 negative photoresist with a thickness of about 4um on the above substrate at a rotation speed of 5000rpm, and bake it on a hot plate at 110℃ for 60s to obtain the following Fig. 20 The structure shown.

[0199] Step 7: Photolithography to create the air bridge shape.

[0200] Based on the two situations in step 6, we discuss each case separately.

[0201] Step 7-1, when the second photoresist is a positive photoresist. Use a UV exposure machine or a laser direct writing device to expose the air bridge area (including the bridge body and the bridge pier area). Since it is a positive photoresist, the photoresist in the exposed area will be removed after development, so the second photoresist above the air bridge area will be removed. Fig.23 As shown. Note that a double-layer photoresist combination is used here. Since the dissolution rate of PMGI SF3 in the developer is faster than that of the unexposed SPR220 photoresist, the PMGI SF3 under the second layer of SPR220 photoresist is dissolved more, thus forming a hollow structure, also known as an undercut structure. The formation of an undercut structure is very important for good stripping. Because it is usually difficult for positive photoresists to form undercut structures after exposure (such as Fig.21As shown, the glue structure formed by the second layer SPR220 after development is a positive trapezoid, rather than an inverted trapezoid like an undercut structure), so a combination of positive photoresist and non-photosensitive photoresist is selected here to form the undercut structure. At the same time, it is noted that the sacrificial layer in the exposed area is also removed when this undercut structure is formed. This is because the sacrificial layer material Al itself can also be etched by the MF319 developer. By controlling the development time, the Al in the corresponding position can be removed while the photoresist is being developed. For the sacrificial layer made of Cr material, the developer cannot remove the sacrificial layer. After the development step, a step of Cr etching solution can be added to etch away the exposed Cr sacrificial layer, thus achieving the same effect. For the Al sacrificial layer, an additional step of Al etching solution can also be added to further remove the Al sacrificial layer exposed after development. Due to the influence of drilling, the sacrificial layer also forms a hollow structure, which is more conducive to the stripping of the air bridge. The following is a set of embodiments, using 320mJ / cm 2 The second layer of SPR220 photoresist is exposed with a dose, developed in MF319 developer for 60 seconds, and then immersed in Al etching solution for 10 seconds (or immersed in Cr etching solution for 30 seconds) to form the undercut structure.

[0202] Step 7-2, the second photoresist is a negative photoresist. Negative photoresist is easier to form an undercut structure. Taking nLof2070 photoresist as an example, a UV exposure machine is used to expose the area outside the bridge body. Since it is a negative photoresist, the photoresist in the exposed area will be retained, and the photoresist in the area where the air bridge is located will be dissolved, thereby forming an air bridge shape with an undercut structure. One embodiment is to apply 200mJ / cm 2 The second photoresist is exposed to a dose of 1000 nm, baked on a 110°C hot plate for 60 seconds, and developed with MF319 developer for 2 minutes to form a Fig. 22 The photoresist structure shown in FIG. 1 is shown in FIG. 1 . Similarly, the exposed Al sacrificial layer will be etched during the development process. An additional etching step using an Al etching solution (or a Cr etching solution) may be added to further remove the exposed sacrificial layer.

[0203] Step 8, ion milling.

[0204] The purpose of ion milling is to remove the natural oxide layer on the coplanar waveguide before evaporating the superconducting air bridge material, and then evaporate the air bridge superconducting material in situ, so as to form a good superconducting contact. One embodiment is to place the above substrate in a coating device with an ion milling function, and use 7sccm of argon gas at a voltage of 400V and a beam current of 21mA for ion milling for 3 minutes. According to the two situations in step 6 and step 7, the structure after ion milling is as follows Fig.23 and Fig.24As shown in the figure. It can be seen that the natural oxide layer on the coplanar waveguide that is not blocked by the photoresist is removed. Note that since the ion milling will indiscriminately bombard the substrate surface with ions, the photoresist on the substrate will also be bombarded by argon ions, which will cause the photoresist to denature. The denatured photoresist is insoluble in the stripping solution, and once it adheres to the desired structure, it will be difficult to remove. As mentioned earlier, the etching method to prepare the air bridge is difficult to remove because the denatured photoresist adheres to the bridge pier structure.

[0205] Step 9, evaporating an air bridge superconducting film.

[0206] The air bridge material can be evaporated by electron beam evaporation, magnetron sputtering and other coating equipment. The air bridge material can be Al, Ta, Nb, TiN, etc. The thickness of the superconducting film is 200 to 500 nm.

[0207] In this embodiment, an electron beam evaporation device is used to evaporate aluminum as the first metal film layer, and a magnetron sputtering machine is used to evaporate the second metal film layer. According to the two situations in step 6 and step 7, the structure after evaporation of the air bridge material is as follows Fig.25 and Fig.26 Note that since an undercut structure is formed here, the superconducting metal film layer on the photoresist surface and the formed air bridge metal film layer are not adhered to each other, which is a necessary condition for successful stripping.

[0208] Step 10, peel off.

[0209] Soak the above substrate in 80℃ Remover PG degumming solution for 10 hours. The photoresist and the film layer above it will be taken away from the substrate when the photoresist dissolves. The superconducting film layer at the air bridge will not be taken away by the photoresist underneath because it is in contact with the coplanar waveguide, so only the superconducting metal in the shape of the air bridge will be left in the end to form an empty bridge structure. After soaking in the degumming solution, rinse with isopropanol and blow dry with dry nitrogen. Isopropanol is soluble in the degumming solution. Isopropanol can clean the degumming solution on the surface of the sample, because the degumming solution is not easy to evaporate, while isopropanol is easy to evaporate. After cleaning, the sample can be quickly dried with a nitrogen gun, which can prevent the sample from being in a semi-wet and semi-dry state and easily absorbing some dirty particles to leave traces, resulting in poor cleanliness.

[0210] Optionally, when the coplanar waveguide material and the air bridge material are both Ta or Nb or TiN, and the sacrificial layer material is Al, the Al etching solution can be immersed after the stripping is completed to ensure that the sacrificial layer is completely removed (without damaging Ta, Nb, TiN). The prepared air bridge structure is shown in Figure 27.

[0211] For the fully enclosed air bridge, the preparation process is the same as above, except that some small holes are usually designed on the bridge body of the fully enclosed air bridge, which is conducive to debonding and stabilizing the air bridge structure. Taking the second photoresist as a positive photoresist combination as an example to prepare a fully enclosed air bridge with holes in the bridge body, steps 1 to 6 are exactly the same as above. Step 7 needs to avoid exposure where there are bridge holes, so that unexposed photoresist is left on the bridge body. Finally, after the air bridge material is evaporated, the superconducting metal at the location of the small hole will also be stripped away, eventually forming a small hole structure. Since there is photoresist under the metal at the location of the small hole (see Fig.28 Step 9), and there is no other support. When immersed in the degumming solution, the photoresist underneath is dissolved, and the metal loses its support and detaches. The bridge body is connected to the piers, and the piers are connected to the substrate, so the superconducting film in the middle of the bridge body will not be taken away by the photoresist underneath.

[0212] The process diagram of preparing the all-inclusive air bridge in steps 7-10 is as follows Fig.28 shown.

[0213] The actual picture of the air bridge prepared by the present invention is as follows Fig.29 , Fig.30 and Figure 2 shown.

[0214] The beneficial effects of the present invention are as follows:

[0215] 1. The air bridge is prepared by the stripping method, which relaxes the restrictions on the material of the air bridge. In principle, any superconducting thin film material can be used to prepare the air bridge using this method, without the need to develop the corresponding etching process;

[0216] 2. Compared with the preparation of air bridges by etching, the present invention can effectively avoid the problem of denatured photoresist residue during stripping;

[0217] 3. The present invention relaxes the restrictions on photoresists. By introducing a sacrificial layer, positive photoresists and negative photoresists can be flexibly used to prepare air bridge structures;

[0218] 4. The process results can be monitored after each step of the process without being affected by the white light environment.

[0219] Taking the second photoresist as a positive photoresist combination as an example, the schematic diagram of the entire process can be as follows: Fig.31 shown.

[0220] Fig.32 FIG. 1 shows a schematic diagram of a chip product preparation system according to an exemplary embodiment of the present application. The chip product preparation system can be implemented as a production line device; Fig.32 As shown, the chip product preparation system includes: a glue coating machine 3201, a photolithography machine 3202, an etching machine 3203, a vapor deposition machine 3204, a developer 3205 and a glue stripping machine 3206;

[0221] By means of the coating machine 3201, the photolithography machine 3202, the evaporation machine 3204, the etching machine 3203, the developing machine 3205 and the degumming machine 3206, a bottom layer circuit is prepared on the substrate to obtain a first chip product;

[0222] Applying a first photoresist on the first chip product by the coating machine 3201;

[0223] By using the photolithography machine 3202 and the developer 3205, the first photoresist at the bridge pier position corresponding to the air bridge on the first chip product is removed to obtain a bridge support structure at the bridge body position of the air bridge, wherein the bridge support structure is formed by the first photoresist;

[0224] Using the evaporation machine 3204, evaporating a first metal film layer on the first chip product;

[0225] Applying a second photoresist on the first chip product by the coating machine 3201;

[0226] By using the photolithography machine 3202 and the developer 3205, the second photoresist at the target position and the first metal film layer at the target position are removed; the target position includes the bridge body position and the bridge pier position;

[0227] Using the evaporation machine 3204, evaporating a second metal film layer on the first chip product;

[0228] The first chip product is placed in a degumming liquid for cleaning by the degumming machine 3206 to obtain a second chip product, wherein the second chip product includes the bottom circuit and the air bridge formed by the second metal film layer.

[0229] In a possible implementation, the photolithography machine 3202 and the developer 3205 are used to perform exposure and development processing on the first chip product after the second photoresist is applied, so as to remove the second photoresist at the target position;

[0230] The etcher 3203 is used to perform etching processing on the first chip product after removing the second photoresist at the target position, so as to remove the first metal film layer at the target position.

[0231] In a possible implementation, the etcher 3203 is used to perform wet etching on the first chip product using an etching solution corresponding to the first metal film layer to remove the first metal film layer at the target position.

[0232] In a possible implementation manner, the first metal film layer is made of metal aluminum or metal chromium.

[0233] In a possible implementation, the coating machine 3201 is used to coat the second photoresist on the first chip product, including: coating the first positive photoresist on the first chip product and baking it;

[0234] The coating machine 3201 is used to coat the second positive photoresist on the first chip product after the first positive photoresist is coated and bake it;

[0235] The photolithography machine 3202 and the developer 3205 are used to perform exposure and development processing on the first chip product after the second photoresist is applied, so as to remove the second photoresist at the target position, and include:

[0236] The photolithography machine 3202 performs exposure processing on the second photoresist at the target position;

[0237] The developer 3205 develops the first chip product using a developer corresponding to the second positive photoresist to remove the first positive photoresist and the second positive photoresist at the target position and form an undercut structure at the edge of the remaining first positive photoresist.

[0238] In another possible implementation manner, the first metal film layer and the second metal film layer may be evaporated by different evaporators.

[0239] In a possible implementation, the thickness of the first positive photoresist is not less than the thickness of the second metal film layer, the thickness of the second positive photoresist is not less than the thickness of the first positive photoresist, the thickness of the first positive photoresist is 0.5um, and the thickness of the second positive photoresist is 3.3um.

[0240] In a possible implementation, the second photoresist is a negative photoresist;

[0241] The photolithography machine 3202 and the developer 3205 are used to perform exposure and development processing on the first chip product after the second photoresist is applied, so as to remove the second photoresist at the target position, and include:

[0242] The photolithography machine 3202 is used to perform exposure processing on the second photoresist outside the target position;

[0243] The developer 3205 is used to develop the first chip product using a developer corresponding to the negative photoresist to remove the second photoresist at the target position and form an undercut structure composed of the remaining second photoresist.

[0244] In a possible implementation manner, the thickness of the negative photoresist is not less than the thickness of the second metal film layer.

[0245] In a possible implementation manner, the first metal film layer remaining after the etching process forms an undercut structure at the target position.

[0246] In a possible implementation manner, the thickness of the first metal film layer is not less than 25 nm.

[0247] In a possible implementation, the evaporator 3204 is used to perform ion milling etching on the first chip product to remove the natural oxide layer at the bridge pier position.

[0248] In a possible implementation, the etcher 3203 is used to immerse the first chip product in an aluminum etching solution to obtain the second chip product.

[0249] In a possible implementation, the air bridge is an all-inclusive air bridge or a discrete air bridge.

[0250] In a possible implementation manner, the second chip product is used to prepare a superconducting quantum chip; or, the second chip product is a superconducting quantum chip.

[0251] Optionally, the system also includes a control chip, which can be electrically connected to at least one of the above-mentioned coating machine 3201, photolithography machine 3202, etcher 3203, evaporation machine 3204, developer 3205 and degumming machine 3206, so as to control the coating machine 3201, photolithography machine 3202, etcher 3203, evaporation machine 3204, developer 3205 and degumming machine 3206, etc.

[0252] Optionally, the production line equipment also includes a power supply to supply power to electrical equipment such as control chips, glue coater 3201, photolithography machine 3202, etcher 3203, evaporation machine 3204, developer 3205 and glue stripper 3206.

[0253] Optionally, the machines are spatially connected via a conveyor belt, or the movement of the prepared products between the machines is accomplished by a robotic arm.

[0254] Optionally, the production line equipment also includes a memory, which can be used to store at least one computer instruction, and the processor executes the at least one computer instruction so that the production line equipment executes the above-mentioned quantum bit component preparation method.

[0255] To sum up, in the scheme shown in the embodiment of the present application, when preparing the air bridge, the first photoresist is first coated on the first chip product by the coating machine 3201, and the first photoresist is photolithographically processed by the photolithography machine 3202, and then reflowed to obtain the bridge support structure of the bridge body of the air bridge. On this basis, the first chip product is evaporated by the evaporation machine 3204 to obtain the first metal film layer, and the second photoresist is continuously coated on the first metal film layer, so that the subsequent peeling of the second metal film layer is more convenient. Since the first metal film layer has a specific etching solution, the subsequent etching operation of the etcher 3203 is convenient and does not damage the photoresist. Since the first metal film layer is between the two layers of photoresist, the cross-linking reaction of the two layers of photoresist due to the principle of like dissolves like is prevented. The cleaning action is completed by the developer 3205 and the stripper 3206. Since the first photoresist will undergo the exposure and development process again with the second photoresist, the formed bridge structure is protected by the first metal film layer from the influence of subsequent exposure, preventing the bridge from being dissolved by the developer during the second development, thereby improving the quality of chip product manufacturing and thus improving the performance of the chip product.

[0256] In addition, the solution shown in the embodiment of the present application also reduces the process steps and improves the yield and processing efficiency.

[0257] Please refer to Fig.33 , which shows a schematic diagram of an application scenario of a solution provided by an embodiment of the present application. Fig.33 As shown, the application scenario may be a superconducting quantum computing platform, which includes: a quantum computing device 331 , a dilution refrigerator 332 , a control device 333 and a computer 334 .

[0258] The quantum computing device 331 is a circuit that acts on a physical quantum bit. The quantum computing device 331 can be realized as a quantum chip, such as a superconducting quantum chip near absolute zero. The quantum chip can be prepared by the scheme shown in the above embodiment of the present application. The dilution refrigerator 332 is used to provide an absolute zero environment for the superconducting quantum chip.

[0259] The control device 333 is used to control the quantum computing device 331, and the computer 334 is used to control the control device 333. For example, the written quantum program is compiled into instructions by the software in the computer 334 and sent to the control device 333 (such as an electronic / microwave control system). The control device 333 converts the above instructions into electronic / microwave control signals and inputs them into the dilution refrigerator 332 to control the superconducting quantum bits at a temperature less than 10mK. The reading process is the opposite, and the reading waveform is transmitted to the quantum computing device 331.

[0260] In an exemplary embodiment, a computer-readable storage medium is also provided, in which at least one computer instruction is stored. The at least one computer instruction is executed by a processor in a chip product preparation system so that the chip product preparation system executes the above-mentioned chip product preparation method.

[0261] In an exemplary embodiment, a computer program product or a computer program is also provided, the computer program product or the computer program includes computer instructions, and the computer instructions are stored in a computer-readable storage medium. A processor of the chip product preparation reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the chip product preparation system performs the above-mentioned chip product preparation method.

[0262] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the claims.

[0263] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for preparing a chip product, characterized in that: The method comprises: Preparing a bottom layer circuit on a substrate to obtain a first chip product; Applying a first photoresist on the first chip product; Removing the first photoresist at the bridge pier position corresponding to the air bridge on the first chip product to obtain a bridge support structure at the bridge body position of the air bridge, wherein the bridge support structure is formed by the first photoresist; Vapor depositing a first metal film layer on the first chip product; Applying a second photoresist on the first chip product; removing the second photoresist at a target position and the first metal film layer at the target position, wherein the target position includes the bridge body position and the bridge pier position; Vapor depositing a second metal film layer on the first chip product; The first chip product is placed in a degumming solution for cleaning to obtain a second chip product, wherein the second chip product includes the bottom layer circuit and the air bridge formed by the second metal film layer.

2. The method according to claim 1, characterized in that The removing of the second photoresist at the target position and the first metal film layer at the target position comprises: performing exposure and development processing on the first chip product after coating the second photoresist, so as to remove the second photoresist at the target position; The first chip product is etched after the second photoresist at the target position is removed to remove the first metal film layer at the target position.

3. The method according to claim 2, characterized in that The etching process is performed on the first chip product after removing the second photoresist at the target position to remove the first metal film layer at the target position, comprising: The first chip product is wet-etched using an etching solution corresponding to the first metal film layer to remove the first metal film layer at the target position.

4. The method according to claim 3, characterized in that The first metal film layer is made of metal aluminum or metal chromium.

5. The method according to claim 2, characterized in that: The second photoresist includes a first positive photoresist and a second positive photoresist; The first positive photoresist is a non-photosensitive positive photoresist, and the second positive photoresist is a photosensitive positive photoresist; The step of applying a second photoresist on the first chip product comprises: Applying the first positive photoresist on the first chip product and baking it; Applying the second positive photoresist on the first chip product after applying the first positive photoresist and baking the product; The step of performing exposure and development processing on the first chip product after coating the second photoresist to remove the second photoresist at the target position includes: performing an exposure process on the second photoresist at the target position; The first chip product is developed using a developer corresponding to the second positive photoresist to remove the first positive photoresist and the second positive photoresist at the target position, and an undercut structure is formed at an edge position of the remaining first positive photoresist.

6. The method according to claim 5, characterized in that The thickness of the first positive photoresist is not less than the thickness of the second metal film layer, and the thickness of the second positive photoresist is not less than the thickness of the first positive photoresist.

7. The method according to claim 2, characterized in that: The second photoresist is a negative photoresist; The step of performing exposure and development processing on the first chip product after coating the second photoresist to remove the second photoresist at the target position includes: performing exposure processing on the second photoresist outside the target position; The first chip product is developed using a developer corresponding to the negative photoresist to remove the second photoresist at the target position, thereby forming an undercut structure composed of the remaining second photoresist.

8. The method according to claim 7, characterized in that The thickness of the negative photoresist is not less than the thickness of the second metal film layer.

9. The method according to claim 2, characterized in that: The first metal film layer remaining after the etching process forms an undercut structure at the target position.

10. The method according to claim 1, characterized in that The thickness of the first metal film layer is not less than 25 nm.

11. The method according to claim 1, characterized in that: Before the second metal film layer is evaporated on the first chip product, the method further includes: The first chip product is ion-milled and etched to remove the natural oxide layer at the bridge pier position.

12. The method according to claim 1, characterized in that When the material of the second metal film layer is tantalum, niobium or titanium nitride, and the first metal film layer is aluminum, the step of placing the first chip product in a degumming solution for cleaning to obtain a second chip product includes: The first chip product is placed in a degumming solution for cleaning, and then immersed in an aluminum etching solution to obtain the second chip product.

13. The method according to any one of claims 1 to 12, characterized in that: The air bridge is a fully-inclusive air bridge or a discrete air bridge.

14. The method according to any one of claims 1 to 12, characterized in that: The second chip product is used to prepare a superconducting quantum chip; or, the second chip product is a superconducting quantum chip.

15. A chip product preparation system, characterized in that: The system includes: a glue coating machine, a photolithography machine, a vapor deposition machine, an etching machine, a developer and a glue stripping machine; By means of the coating machine, the photolithography machine, the developing machine, the evaporation machine, the etching machine and the degumming machine, a bottom layer circuit is prepared on a substrate to obtain a first chip product; Applying a first photoresist on the first chip product by the coating machine; Using the photolithography machine and the developer, removing the first photoresist at the bridge pier position corresponding to the air bridge on the first chip product, and obtaining a bridge support structure at the bridge body position of the air bridge, wherein the bridge support structure is composed of the first photoresist; Using the evaporation machine, evaporating a first metal film layer on the first chip product; Applying a second photoresist on the first chip product by the coating machine; Using the photolithography machine and the developer, removing the second photoresist at the target position and the first metal film layer at the target position; the target position includes the bridge body position and the bridge pier position; Using the evaporation machine, evaporating a second metal film layer on the first chip product; The first chip product is placed in a degumming liquid for cleaning by the degumming machine to obtain a second chip product, wherein the second chip product includes the bottom circuit and the air bridge formed by the second metal film layer.

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