Method and system for manufacturing chip product

Abstract

A method and system for manufacturing a chip product, which method and system relate to the technical field of micro-nano fabrication. The method comprises: applying a first photoresist onto a first chip product (701); removing the first photoresist from a first region, so as to obtain a bridge support structure used for constructing the bridge body of an air bridge, wherein the first region is a region occupied on the first chip product by a bridge pier of the air bridge (702); evaporating a first metal film layer (703); applying a second photoresist (704); removing the second photoresist and the first metal film layer from a second region, wherein the second region comprises the bridge support structure and the bridge pier (705); evaporating a second metal film layer on the first chip product (706); and dissolving the first photoresist on the first chip product, so as to obtain a second chip product, wherein the second chip product includes an air bridge formed by the second metal film layer, and the first metal film layer outside the second region is stripped as the first photoresist dissolves (707). The present application can improve the flexibility of manufacturing an air bridge.

Description

Chip product preparation method and system

[0001] This application claims priority to Chinese patent application number 202311249292.8, filed on September 25, 2023, entitled “Chip Product Preparation Method and System,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] 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

[0003] In the chip field, an air bridge is a circuit structure (device) that realizes planar circuit bridging in a three-dimensional bridge-like manner.

[0004] In related technologies, air bridge stripping techniques often use methods such as chemical etching or mechanical scraping to separate ineffective bridging wires from the chip product surface to create an air bridge. For example, a production machine spin-coats multiple layers of photoresist onto the chip substrate while using a mask to expose the photoresist to dissolve in a developer to create a bridge support structure. Tin is then evaporated to form the initial air bridge. Finally, exposure or other methods are used to dissolve the photoresist and strip away the ineffective bridging portion of the initial air bridge, thus creating the final air bridge.

[0005] However, in the above scheme, due to the principle of like dissolves like of photoresists, most photoresists cannot be used together, thereby limiting the flexibility of preparing the air bridge.

[0006] Summary of the Invention

[0007] The embodiments of the present application provide a chip product preparation method and system, and the technical solution may include the following contents.

[0008] In one aspect, a method for preparing a chip product is provided, the method comprising:

[0009] Applying a first photoresist on the first chip product;

[0010] Removing the first photoresist in a first area on the first chip product to obtain a bridge support structure for constructing a bridge body of an air bridge, wherein the first area is an area occupied by a bridge pier of the air bridge on the first chip product, and the bridge support structure is formed by the first photoresist;

[0011] vapor-depositing a first metal film layer on the first chip product;

[0012] Applying a second photoresist on the first chip product;

[0013] removing the second photoresist in a second area on the first chip product and the first metal film layer in the second area, wherein the second area includes the bridge structure and the bridge pier;

[0014] Vapor-depositing a second metal film layer on the first chip product;

[0015] The first photoresist on the first chip product is dissolved to obtain a second chip product, wherein the second chip product includes the air bridge formed by the second metal film layer, and the first metal film layer outside the second area is peeled off as the first photoresist is dissolved.

[0016] On the other hand, a chip product preparation system is provided, the system comprising: a resist engraving machine, a resist coating machine, a vapor deposition machine, an etching machine and a resist stripping machine, the resist engraving machine comprising a photoresist and a developer;

[0017] The coating machine is used to apply a first photoresist on the first chip product;

[0018] The photoresist is configured to remove the first photoresist in a first area on the first chip product to obtain a bridge support structure for constructing a bridge body of an air bridge, wherein the first area indicates an area occupied by a bridge pier of the air bridge on the first chip product, and the bridge support structure is formed by the first photoresist;

[0019] The evaporation machine is used to evaporate a first metal film layer on the first chip product;

[0020] The coating machine is used to apply a second photoresist on the first chip product;

[0021] The photoresist is configured to remove the second photoresist in a second area on the first chip product and the first metal film layer in the second area, wherein the second area includes the bridge structure and the bridge pier;

[0022] The evaporation machine is used to evaporate a second metal film layer on the first chip product;

[0023] The stripping machine is used to dissolve the first photoresist on the first chip product to obtain a second chip product. The second chip product includes the air bridge composed of the second metal film layer. The first metal film layer outside the second area is peeled off as the first photoresist is dissolved.

[0024] In a possible implementation, the photoresist is configured to expose and develop the first chip product after the second photoresist is applied, so as to remove the second photoresist in the second region to obtain a processed first chip product.

[0025] The etcher is used to etch the processed first chip product to remove the first metal film layer in the second area.

[0026] In a possible implementation, the etcher is configured to wet-etch the processed first chip product using an etching solution corresponding to the first metal film layer to remove the first metal film layer in the second region.

[0027] 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;

[0028] The coating machine is used to coat the first positive photoresist on the first chip product;

[0029] The coating machine is used to coat the second positive photoresist on the first chip product after the first positive photoresist is coated;

[0030] The photolithography machine is used to expose the second photoresist in the second area;

[0031] The developer is used to develop the first chip product using a developer corresponding to the second positive photoresist to remove the first positive photoresist and the second positive photoresist in the second area, and to form an undercut structure at the edge of the remaining first positive photoresist to obtain the processed first chip product.

[0032] In another possible implementation, the first metal film layer and the second metal film layer may be evaporated by different evaporation machines.

[0033] 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.

[0034] In a possible implementation, the second photoresist is a negative photoresist;

[0035] The photolithography machine is used to expose the second photoresist outside the second area;

[0036] The developer is used to develop the first chip product using a developer corresponding to the negative photoresist to remove the second photoresist in the second area, forming an undercut structure composed of the remaining second photoresist, and obtaining the processed first chip product.

[0037] In a possible implementation, the thickness of the negative photoresist is not less than the thickness of the second metal film layer.

[0038] In a possible implementation, after etching, the remaining first metal film layer forms an undercut structure.

[0039] In a possible implementation, the material of the first metal film layer includes any one of the following: metal aluminum and metal chromium.

[0040] In a possible implementation, the thickness of the first metal film layer is not less than 25 nm.

[0041] In a possible implementation, the evaporator is used to perform ion milling etching on the first chip product to remove the natural oxide layer in the first region.

[0042] In a possible implementation, the evaporation machine is used to in-situ evaporate the second metal film layer on the first chip product.

[0043] In a possible implementation, the debonding machine is used to debond the first chip product and peel off the second metal film layer.

[0044] In one possible implementation, the etcher is used to place the first chip product in an aluminum etching solution for immersion after the first chip product is placed in a degumming solution for cleaning when the material of the second metal film layer includes any one of the following: tantalum, niobium, and titanium nitride, and the first metal film layer is aluminum, so as to obtain the second chip product.

[0045] In a possible implementation, the air bridge includes any one of the following: an all-inclusive air bridge and a discrete air bridge.

[0046] In a possible implementation, the second chip product is used to prepare a superconducting quantum chip; or, the second chip product is a superconducting quantum chip.

[0047] The beneficial effects of the technical solutions provided in the embodiments of the present application include at least:

[0048] In the process of preparing the air bridge, after the bridge support structure is constructed by the first photoresist, the first metal film layer is first evaporated, and then the second photoresist is applied. On this basis, the second photoresist and the first metal film layer in the second area are removed, so that the second metal film layer can be directly distilled on the bridge support structure to construct the air bridge. Finally, the first photoresist is dissolved, and the second photoresist and the second metal film layer outside the second area can be peeled off to obtain a clean air bridge. In this way, isolation is formed between the first photoresist structure and the second photoresist by the first metal film layer, which can prevent the two layers of photoresist from producing a cross-linking reaction due to the principle of like dissolves like, breaking through the matching restrictions of the photoresist, allowing the preparation personnel to flexibly match the first photoresist and the second photoresist, thereby improving the flexibility of photoresist matching during the preparation of the air bridge, and thus improving the flexibility of air bridge preparation.

[0049] Furthermore, the first photoresist undergoes the exposure and development process again along with the second photoresist. However, protected by the first metal film layer, the resulting bridge structure is protected from the effects of subsequent exposure, preventing dissolution of the bridge structure by the developer during the second development process. This ensures the quality of the bridge structure, thereby improving the quality of the air bridge, which in turn contributes to improved chip product manufacturing quality and performance. Furthermore, the bridge structure, protected by the first metal film layer, allows the air bridge to be exposed to white light during fabrication, enabling unrestricted measurement of the air bridge (e.g., the bridge structure) during fabrication.

[0050] Furthermore, by dissolving the first photoresist, the useless second metal film layer can be stripped away, retaining the useful second metal film layer (i.e., the air bridge) within the second region without etching the second metal film layer. This effectively improves the ease and efficiency of stripping the useless second metal film layer, thereby facilitating improved air bridge fabrication efficiency. Furthermore, since there is no need to etch the second metal film layer, the material restrictions imposed by the etching process on the second metal film layer are avoided, making any metal material that can be used to fabricate an air bridge applicable. This increases the flexibility of the second metal film layer and, in turn, effectively improves the flexibility of air bridge fabrication.

[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] FIG1 is a side view of an air bridge provided by one embodiment of the present application;

[0053] FIG2 is a schematic diagram of a discrete air bridge and a fully enclosed air bridge provided in one embodiment of the present application;

[0054] FIG3 is a flow chart of preparing an aluminum air bridge by etching method provided by related art;

[0055] FIG4 is a schematic cross-sectional view of an air bridge prepared by an etching method before resist removal according to an embodiment of the present application;

[0056] FIG5 is a schematic diagram of an embodiment of the present application of an etching method for preparing an air bridge and a denatured photoresist residue;

[0057] FIG6 is a flow chart of preparing an aluminum air bridge by a stripping method provided in the related art;

[0058] FIG7 is a flow chart of a method for preparing a chip product according to an embodiment of the present application;

[0059] FIG8 is a schematic diagram of applying a first photoresist according to an embodiment of the present application;

[0060] FIG9 is a schematic diagram of a bridge support structure provided by one embodiment of the present application;

[0061] FIG10 is a schematic diagram of a first metal film layer evaporated according to an embodiment of the present application;

[0062] FIG11 is a schematic diagram of applying a second photoresist according to an embodiment of the present application;

[0063] FIG12 is a schematic diagram of applying a second photoresist according to another embodiment of the present application;

[0064] FIG13 is a schematic diagram of constructing an undercut structure provided by one embodiment of the present application;

[0065] FIG14 is a schematic diagram of constructing an undercut structure provided by another embodiment of the present application;

[0066] FIG15 is a schematic diagram of a second metal film layer evaporated according to an embodiment of the present application;

[0067] FIG16 is a schematic diagram of a second metal film layer evaporated according to another embodiment of the present application;

[0068] FIG17 is a schematic diagram of an air bridge obtained after peeling provided by one embodiment of the present application;

[0069] FIG18 is a flow chart of a method for preparing a chip product according to another embodiment of the present application;

[0070] FIG19 is a flow chart of a chip product manufacturing method provided by another embodiment of the present application;

[0071] FIG20 is a schematic diagram of a bridge support structure provided by another embodiment of the present application;

[0072] FIG21 is a schematic diagram of a first metal film layer evaporated according to another embodiment of the present application;

[0073] FIG22 is a schematic diagram of a damaged air bridge provided by one embodiment of the present application;

[0074] FIG23 is a schematic diagram of applying a second photoresist (positive photoresist combination) according to another embodiment of the present application;

[0075] FIG24 is a schematic diagram of applying a second photoresist (negative photoresist) according to another embodiment of the present application;

[0076] FIG25 is a schematic diagram of constructing an undercut structure (positive resist combination) provided by another embodiment of the present application;

[0077] FIG26 is a schematic diagram of constructing an undercut structure (negative resist) according to another embodiment of the present application;

[0078] FIG27 is a schematic diagram of ion milling (positive resist combination) provided by one embodiment of the present application;

[0079] FIG28 is a schematic diagram of ion milling (negative photoresist) provided by another embodiment of the present application;

[0080] FIG29 is a schematic diagram of evaporating a second metal film layer (positive resist combination) according to another embodiment of the present application;

[0081] FIG30 is a schematic diagram of evaporating a second metal film layer (negative photoresist) according to another embodiment of the present application;

[0082] FIG31 is a schematic diagram of an air bridge obtained after peeling provided by another embodiment of the present application;

[0083] FIG32 is a schematic diagram of preparing a bridge hole according to an embodiment of the present application;

[0084] FIG33 is a schematic diagram of a discrete air bridge provided by one embodiment of the present application;

[0085] FIG34 is a schematic diagram of an all-inclusive air bridge provided by one embodiment of the present application;

[0086] FIG35 is a schematic diagram of a chip product manufacturing system provided by one embodiment of the present application;

[0087] FIG36 is a schematic diagram of an application scenario of a solution provided by an embodiment of the present application. DETAILED DESCRIPTION

[0088] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0089] Superconductor: refers to a material with superconducting properties. Superconducting properties mean that below a certain temperature, the resistance of the material suddenly drops to 0 and it has complete anti-magnetic properties.

[0090] Superconducting Quantum Chip: A chip used for superconducting quantum computing. Superconducting quantum chips can be made from superconducting thin films deposited on substrates such as silicon or sapphire. They can include devices such as coplanar waveguides, air bridges, and superconducting qubits, all of which can be fabricated from superconducting thin films using processes such as photolithography.

[0091] 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.

[0092] Airbridge: A device in a superconducting quantum chip, similar to an arch bridge structure, spanning an infinite ground plane on either side of a coplanar waveguide. An airbridge consists of a bridge body and piers. Piers are areas on the underlying circuit structure reserved for contact between the airbridge and the underlying circuitry. The bridge body connects to the piers and can be constructed using an airbridge support structure. The support structure sits between the airbridge and the underlying circuitry, supporting the bridge body before the airbridge is formed. Once the airbridge is completed, the support structure is removed using a debonding solution.

[0093] Discrete Airbridge: A common airbridge structure, where the span and width of the bridge are of the same order of magnitude.

[0094] 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.

[0095] Lithography & Development: A micro-nanofabrication technology primarily involving ultraviolet lithography, which involves coating a photoresist on the surface of a substrate sample. Ultraviolet light is then directed through a mask onto the substrate surface, and a photochemical reaction is used to change the properties of the light-exposed portion of the photoresist. The light-reactive area is then dissolved in a specific solution to create a specific pattern on the substrate surface.

[0096] Photoresist: A colloid that, when exposed to ultraviolet light or electron beam bombardment (also known as photolithography), undergoes chemical changes in the exposed or bombarded areas, and its solubility is significantly different from that of the unexposed or unbombarded areas, allowing the desired pattern to be produced. Photoresists include positive photoresists (abbreviated as positive photoresists) and negative photoresists (abbreviated as negative photoresists). The areas of positive photoresists exposed to ultraviolet light are removed during development, while the areas of negative photoresists exposed to ultraviolet light remain after development.

[0097] Reflow: refers to the process of heating the substrate coated with photoresist to a specific temperature before the photoresist is exposed, so that the photoresist dissolves on the substrate to form a smooth coating.

[0098] Etching: A micromachining process that uses dry (other) and wet (liquid) methods to corrode metal or other materials to form the required structure.

[0099] Lift-off technology refers to a process in which a substrate is coated with photoresist (photoresist), exposed, and developed, and then the photoresist film with a certain pattern is used as a mask to deposit the required material, such as metal, through evaporation and other methods. Then, while removing the photoresist, the non-required materials on the film are stripped away, leaving only the material structure of the original pattern on the substrate.

[0100] Sacrificial Layer: A metal film used in micro-nano processing to prepare the desired structure on top of the film, and then remove the film to retain the prepared structure.

[0101] In Situ conditions: refers to the conditions where multiple steps of the process are carried out in a single vacuum chamber or multiple interconnected vacuum chambers without exposure to the atmospheric environment.

[0102] Ion milling: refers to the process of using an ion source to generate Ar (argon) ions to bombard the metal surface in a vacuum to remove the natural oxide layer on the metal surface.

[0103] Undercut: A structure where the top opening of the photoresist is smaller than the bottom opening after development. This occurs when the photoresist dissolves or erodes unevenly during development, creating an inward depression at the edge of the photoresist below the mask opening.

[0104] In some embodiments, superconducting quantum chips rely on coplanar waveguides on the substrate to transmit microwave signals. As the complexity of the chip increases, the number of coplanar waveguides also increases, and the coplanar waveguides become increasingly 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 signal crosstalk is to shield the microwave signals on the coplanar waveguide through an air bridge. Generally, the air bridge connects the infinite ground planes on both sides of the coplanar waveguide so that the infinite ground planes on both sides are at the same electric potential. In addition, the air bridge can also serve as a cross-line to connect the central conductors of two separate coplanar waveguides, so that microwaves are transmitted through the air bridge, making the wiring of the superconducting quantum chip more flexible.

[0105] The materials currently used to prepare air bridges on superconducting quantum chips include superconducting metals such as aluminum (Al), tantalum (Ta), niobium (Nb), and titanium nitride (TiN). Superconducting Al films prepared from Al are the most widely used air bridge materials because they are easy to etch. According to the ratio of the span and width of the air bridge body (the distance between the bridge 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: stand-alone air bridges and all-inclusive air bridges. Optionally, holes can be opened in the 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 photoresist is removed more cleanly, and the bridge holes also make the structure of the air bridge more stable.

[0106] Please refer to Figure 1, which is a side view of an air bridge provided by one embodiment of the present application. An air bridge 130 is fabricated on the substrate 101 of the superconducting quantum chip. Air bridge 130 connects the infinite ground planes on both sides of the coplanar waveguide 102. Air bridge 130 includes a bridge body 1301 and two bridge piers 1302. During the fabrication process of air bridge 130, before the final photoresist removal, the underside of bridge body 1301 is filled with photoresist to form a bridge support structure. The bridge support structure is used to construct bridge body 1301, and this photoresist is ultimately removed.

[0107] For another example, referring to FIG2 , a discrete air bridge 202 and a fully enclosed air bridge 203 are fabricated on the substrate 201 of a superconducting quantum chip. During the fabrication of the fully enclosed air bridge 203 , if there are no openings on the bridge body of the fully enclosed air bridge 203 , the photoresist can only flow out through the two ends of the bridge. If there are openings on the bridge body of the fully enclosed air bridge 203 (such as small rectangles on the bridge body of the fully enclosed air bridge 203 ), the debonding liquid can pass through these small holes and bring out the photoresist under the bridge body. If there are no openings on the bridge body of the fully enclosed air bridge 203 , the fully enclosed air bridge 203 can only circulate liquid through the openings at both ends of the bridge. This requires megasonic cleaning (high-speed liquid flow) during debonding. When the liquid impacts the bridge body, the pressure difference can easily cause the fully enclosed air bridge 203 to deform. If there are openings on the bridge body of the fully enclosed air bridge 203 , high-speed liquid can enter and exit the bridge body through the holes, thus alleviating the pressure difference on both sides of the bridge and making the bridge body less susceptible to damage.

[0108] In some embodiments, the air bridge fabrication process can be divided into two categories: etching and lift-off. Since Al is currently the most widely used air bridge material and is relatively easy to etch with an etchant, etching is the most widely used method.

[0109] Referring to Figure 3, in the relevant technology, the etching method can generally include the following contents: 1. Obtain a substrate with a coplanar waveguide; 2. Spin-coat a first photoresist; 3. Photoetch bridge piers; 4. High-temperature reflow to obtain a bridge support structure composed of the first photoresist; 5. Ion milling to remove a natural oxide layer on the upper surface of the coplanar waveguide; 6. Aluminum plating; 7. Spin-coat a second photoresist; 8. Photoetch the area outside the air bridge (i.e., the area except the bridge body and the bridge piers) to depict the air bridge structure; 9. Etch aluminum (i.e., etch the aluminum outside the air bridge structure) to obtain an air bridge composed of aluminum; 10. Stripping (i.e., removing the first photoresist and the second photoresist).

[0110] However, the etching method in the related art solution has the following disadvantages:

[0111] 1. There are many limitations on the materials used to prepare air bridges. For example, for wet etching, Al etching is relatively easy to achieve, and 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 for etching, and the etching solution often damages the photoresist, so Al is mostly used to prepare air bridges. For dry etching, dry etching requires additional etching equipment and special process gases, and the corresponding etching process needs to be explored, which greatly limits the use of superconducting metal materials other than Al. In addition, existing data show that superconducting quantum chips prepared by Ta have better performance than superconducting quantum chips prepared by Al, so the preparation of air bridges by Al etching method can no longer meet the needs of diversified air bridge preparation.

[0112] 2. Difficulty removing the air bridge. Before evaporating the superconducting metal material used to form the air bridge, ion milling is performed in situ to remove the native oxide layer on the coplanar waveguide, ensuring a good superconducting contact between the coplanar waveguide and the air bridge. However, during the ion milling process, the photoresist is bombarded by Ar ions and denatured. The denatured photoresist is insoluble in the stripping solution, making it difficult to remove. For example, referring to FIG4 , a cross-section before etching is shown in FIG4 . An air bridge 409 (such as a bridge-shaped superconducting film constructed of Al) is constructed for the coplanar waveguide 402 on the substrate 401. At this time, the bridge body is supported by the first photoresist 404 (such as SPR220 photoresist), and the second photoresist 410 (such as SPR220 photoresist) in the area outside the air bridge is removed by photolithography. During the process of removing the natural oxide layer 403 by ion milling, the surface of the first photoresist 404 is also bombarded by Ar ions and denatured, forming a denatured photoresist 408. In addition, during the process of 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. This will cause the bridge pier to adhere to the denatured photoresist 408 (such as the circled portion in FIG4 ). During stripping, this portion of the denatured photoresist 408 that adheres is not easy to remove. For example, referring to FIG. 5 , in region 501 , part of the denatured photoresist is adhered to the pier of the air bridge and cannot be removed.

[0113] Referring to Figure 6, in the related art, the stripping method can generally include the following: 1. Obtain a substrate with a coplanar waveguide; 2. Spin-coat a first photoresist (such as PMGI SF15) on the substrate; 3. Spin-coat a second photoresist (such as S1813); 4. Photolithography the area outside the air bridge, such as using a mask to expose the area outside the air bridge. For example, since S1813 is a positive photoresist, the S1813 outside the bridge will be developed away. At the same time, since PMGI SF15 is a non-photosensitive material and can be dissolved in the developer, the PMGI SF15 not covered by S1813 will also be dissolved by the developer. At the same time, since the dissolution rate of PMGI SF15 is higher than that of the unexposed S1813 photoresist, a hollow structure is formed under the S1813 photoresist; 5. Flood exposure: Expose the unexposed photoresist without using a mask; 6. Develop and remove the second photoresist. At this time, the S1813 on the bridge will dissolve in the developer due to exposure. At the same time, the PMGI SF15 corresponding to the bridge area will continue to be dissolved by the developer. This step requires special attention to the development time. Both S1813 and PMGI should not be dissolved too much. SF15, the underlying coplanar waveguide cannot be etched away, and the process is relatively difficult; 7. High-temperature reflow to form an arched bridge structure; 8. Spin-coating negative photoresist (such as SU-8); 9. Photolithography of the area outside the air bridge. Since SU-8 is a negative photoresist, the photoresist in the exposed area will be retained, and the unexposed photoresist will be developed away. Therefore, the SU-8 photoresist corresponding to the area outside the air bridge will be retained, and the SU-8 photoresist in the area where the air bridge is located will be developed away; 10. Ion milling; 11. Aluminum plating, evaporating Al to form an air bridge; 12. Stripping, while the photoresist is dissolved, the excess Al is taken away.

[0114] However, the stripping method in the related art solution has the following disadvantages:

[0115] 1. There are strong restrictions on photoresists. The idea of ​​preparing air bridges by the stripping method is to use positive photoresist to form the bridge support, and then use negative photoresist to define the shape of the air bridge. This requires that the positive photoresist and negative photoresist are immiscible. However, for most photoresists, due to their similar composition, according to the principle of like dissolves like, many photoresists cannot be used together. For example, PMGI SF15 (non-photosensitive photoresist) and SU-8 photoresist are immiscible, and PMGI SF15 can be formed into an arch shape through high-temperature reflow, which can prepare air bridges. 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 place strong restrictions on the process. This method also cannot use positive photoresist or negative photoresist at the same time to prepare air bridges.

[0116] 2. Inconvenient measurement of intermediate processes. After the bridge 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 positive photoresist is used to prepare the bridge, the shape of the bridge must be observed after negative photoresist exposure. Otherwise, the bridge part will be exposed prematurely. During the development process of negative photoresist, the bridge will also be developed, thus losing its shape and causing process failure. If the shape of the bridge is observed after the negative photoresist is developed, the intermediate process of the process cannot be observed.

[0117] To address the above issues, the present invention proposes an optimized air bridge fabrication method that not only avoids the limitations of air bridge materials (including photoresist and superconducting metal materials), but also addresses the difficulty of photoresist removal. Furthermore, it facilitates detection during the process, enabling timely measurement after the bridge is formed. The technical solutions provided in the present invention are described in detail below.

[0118] Please refer to Figure 7, which is a flow chart of a chip product manufacturing method provided by an embodiment of the present application. As shown in Figure 7, the method may include the following steps (steps 701-707):

[0119] Step 701: Apply a first photoresist on a first chip product.

[0120] The first chip product may refer to a chip product for which an air bridge is to be prepared, such as the superconducting quantum chip described above. Optionally, the first chip product includes a base (i.e., a substrate) and an underlying circuit prepared on the base. The underlying circuit may be composed of at least one of the following: a coplanar waveguide, a pickup line, a resonant cavity, a bit capacitor, a control line, an air bridge, a Josephson junction, an indium pillar solder joint, and a deep via. The air bridge to be prepared includes any of the following: a discrete air bridge and an all-inclusive air bridge.

[0121] Optionally, the first chip product may be a semi-finished product in the process of preparing a final finished chip. For example, the substrate of the first chip product includes at least one coplanar waveguide, and the air bridge to be prepared is used to connect the infinite ground planes on both sides of the coplanar waveguide or to connect two different coplanar waveguides, although this embodiment of the present application is not limited to this.

[0122] The substrate may be a sapphire substrate or a high-resistance silicon substrate, and the underlying circuit may be fabricated by photolithography-development-deposition. Alternatively, the underlying circuit may be fabricated by coating-photolithography-etching. Alternatively, the underlying circuit may be fabricated by nanoimprinting, which is not limited in the present embodiment.

[0123] In some embodiments, the etching method (i.e., the "coating-photolithography-etching" preparation method) has a more precise line width than the stripping method (i.e., the "photolithography-development-deposition" preparation method mentioned above), which is required by the underlying circuit, and the air bridge does not have high requirements on the line width.

[0124] In an embodiment of the present application, the first photoresist is used to construct a bridge structure. The first photoresist can be any photosensitive photoresist with a reflow property, and the reflow property can be used to form a bridge structure, such as an arched bridge structure. Optionally, the first photoresist can be a positive photoresist or a negative photoresist. For example, the first photoresist can be any one of the following positive photoresists: SPR220, S1813, PMMAA4, SU-8, PMGI SF15, or any one of the following negative photoresists: nLof2070, AZ5214, E3510, which is not limited in this embodiment of the present application.

[0125] Optionally, a first photoresist layer can be applied to the first chip product using a coating machine. The coating machine can evenly apply the first photoresist to the surface of the first chip product to evenly cover the preparation area where the air bridge is to be formed. The area of ​​the preparation area is larger than the area required to be occupied by the air bridge (hereinafter referred to as the air bridge area). For example, the preparation area can be determined based on the coplanar waveguide.

[0126] The present embodiment does not limit the coating thickness of the first photoresist, which can be set and adjusted according to actual use requirements (such as the height of the bridge body). For example, the coating thickness of the first photoresist ranges from 3 μm (micrometers) to 4 μm, and the coating thickness of the first photoresist can be set to 3.3 μm.

[0127] For example, referring to Figure 8, for the coplanar waveguide 802 on the substrate 801 of the first chip product, a natural oxide layer 803 is naturally formed in the air. During the preparation of the air bridge for the coplanar waveguide 802 on the substrate 801 of the first chip product, a first photoresist 804 is first coated on the first chip product, and the first photoresist 804 covers the preparation area corresponding to the coplanar waveguide 802.

[0128] Step 702 , remove the first photoresist in the first area on the first chip product to obtain a bridge support structure for constructing the bridge body of the air bridge. The first area is the area occupied by the bridge piers of the air bridge on the first chip product, and the bridge support structure is composed of the first photoresist.

[0129] The first area refers to the area of ​​the piers where the air bridge is to be constructed, which can be determined according to the size of the piers. For example, the first area can be determined according to the position and area of ​​the piers.

[0130] Optionally, the first photoresist in the first region is removed by adopting an exposure process and a development process to obtain a bridge structure. This process will be described in detail below and will not be repeated here.

[0131] The embodiment of the present application does not limit the size of the bridge support structure, which can be set and adjusted according to actual use requirements. Optionally, the bridge support structure is arched.

[0132] Among them, the position of the bridge support structure and the position of the above-mentioned bridge piers can be pre-defined by the designer and located at a specified position in the underlying circuit, which is not limited in the embodiment of the present application.

[0133] For example, referring to FIG9 , for a coplanar waveguide 802, the first photoresist 804 in the first region is removed to obtain a bridge support structure 805 for constructing the bridge body of the air bridge. The bridge support structure 805 is formed of the first photoresist 804. The bridge support structure 805 is arched and spans the infinite ground plane on both sides of the coplanar waveguide 802.

[0134] Optionally, the first region is part of the preparation region, and the first region is smaller than the preparation region. In step 702, the first photoresist outside the first region is retained (such as the first photoresist 804 retained at the left and rear ends in FIG9 ). If the second region is the area required to be occupied by the air bridge on the first chip product, the first photoresist outside the second region is retained, the second region is smaller than the preparation region, and the second region includes the first region.

[0135] Step 703: vapor-deposit a first metal film layer on the first chip product.

[0136] The first metal film layer is used to separate the first photoresist described above from the second photoresist described below, preventing them from intermixing. The first photoresist is used to construct the bridge structure, while the second photoresist is used to construct the undercut structure used to form the air bridge. Adding the first metal film layer between the first and second photoresists prevents the constructed bridge structure from being damaged by the second photoresist, thereby enabling the formation of the air bridge.

[0137] In an embodiment of the present application, the first metal film layer can be implemented as a sacrificial layer, and the first metal film layer can be constructed of a metal material that can be used to construct a sacrificial layer and the corresponding etching solution does not damage the photoresist. Optionally, the material of the first metal film layer includes any one of the following: metal aluminum, metal chromium. For example, the material of the above-mentioned first metal film layer can be metal aluminum or metal chromium, which has a specific etching solution. Since metal aluminum and metal chromium have specific etching solutions and the etching solution does not damage the photoresist, this is conducive to the subsequent etching of the first metal film layer without damaging the photoresist, thereby improving the convenience of constructing the air bridge.

[0138] In one example, the thickness of the first metal film layer is between a few nanometers and tens of nanometers. In some embodiments, the thickness of the first metal film layer is not less than 25 nm (nanometers). For example, the thickness of the first metal film layer can be 28 nanometers. The embodiments of the present application do not limit the thickness of the first metal film layer, which can be set and adjusted according to actual use requirements.

[0139] In an embodiment of the present application, since photoresist will be spin-coated on the first metal film layer later, the substrate will undergo high-speed rotation and baking again. The thinner metal film layer will tear under high-speed rotation. By setting the thickness of the first metal film layer to be no less than 25 nanometers, the first metal film layer can be prevented from tearing, thereby preventing the first photoresist and the second photoresist from dissolving. In addition, after spin-coating the photoresist, it will be baked 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 structure well and may also be deformed again. By setting the thickness of the first metal film layer to be no less than 25 nanometers, the first metal film layer can be prevented from being deformed again, thereby preventing the constructed bridge structure from being destroyed.

[0140] Optionally, the deposition area of ​​the first metal film layer can be the same as the preparation area. In an embodiment of the present application, the first metal film layer can be deposited on the first chip product using an evaporation machine. For example, the first chip product can be placed in a vacuum coating device to complete the evaporation of the first metal film.

[0141] For example, referring to FIG10 , for a coplanar waveguide 802 , a first metal film layer 806 is evaporated in its corresponding preparation area, and the first metal film layer 806 uniformly covers the preparation area, especially the area where the first photoresist 804 is located.

[0142] Step 704: Apply a second photoresist on the first chip product.

[0143] The second photoresist is used to construct an undercut structure for forming an air bridge. In the embodiment of the present application, the undercut structure is used to separate the second metal film layer in the second region from the second metal film layer in other regions, thereby forming an air bridge.

[0144] Optionally, the coating area of ​​the second photoresist is the same as the preparation area described above. The present embodiment does not limit the coating thickness of the second photoresist, which can be set and adjusted according to actual use requirements (such as bridge height). Exemplarily, the coating thickness of the second photoresist ranges from 4 μm to 4.5 μm, and the coating thickness of the second photoresist can be set to 4.3 μm.

[0145] In one example, since negative photoresist is easier to form an undercut structure, the second photoresist can be a negative photoresist, and the second photoresist can be any one of the following negative photoresists: nLof2070, AZ5214, E3510, which is not limited in this embodiment of the present application.

[0146] In one example, since positive photoresist is difficult to form an undercut structure after exposure, a combination of a positive photoresist and a non-photosensitive photoresist can also be used to form the undercut structure. For example, the second photoresist includes a first positive photoresist and a second positive photoresist, where the first positive photoresist is a non-photosensitive positive photoresist and the second positive photoresist is a photosensitive positive photoresist. The first positive photoresist and the second positive photoresist can be configured and adjusted according to actual use. For example, if the first positive photoresist is PMGI SF3, the second positive photoresist can be SPR220.

[0147] In the embodiment of the present application, a layer of second photoresist can be coated on the first chip product by a coating machine.

[0148] For example, referring to Figure 11 , a negative photoresist 807 may be directly spin-coated on the preparation area to achieve the application of the second photoresist. For another example, referring to Figure 12 , a first positive photoresist 8081 may be spin-coated on the preparation area first, followed by a second positive photoresist 8082, to achieve the application of the second photoresist.

[0149] Step 705 : removing the second photoresist and the first metal film layer in the second area on the first chip product, wherein the second area includes the bridge structure and the bridge pier.

[0150] The second area is the area that the air bridge needs to occupy on the first chip product.

[0151] Optionally, the second photoresist in the second area is removed by adopting an exposure process and a development process, and the first metal film layer in the second area is removed by an etching process, so as to retain the lower bridge support structure while forming a bottom cut structure at the edge of the second area. This process will be described in detail below and will not be repeated here.

[0152] The position of the bridge support structure and the position of the bridge pier may be pre-defined by a designer and located at a designated position in the bottom circuit.

[0153] For example, referring to FIG13 , when the second photoresist 807 is a negative photoresist, the bridging structure 805 is retained in the second region, undercut structures are formed on both sides of the preparation region, and both the second photoresist 807 and the first metal film layer 806 form undercut structures. For another example, referring to FIG14 , when the second photoresist includes a first positive photoresist 8081 and a second positive photoresist 8082, the bridging structure 805 is retained in the second region, undercut structures are formed on both sides of the preparation region, and both the first positive photoresist 8081, the second positive photoresist 8082, and the first metal film layer 806 form undercut structures.

[0154] Step 706: vapor-deposit a second metal film layer on the first chip product.

[0155] The second metal film layer is used to construct an air bridge, such as one based on the bridge support structure and undercut structure formed above. Because the embodiments of the present application can peel off the air bridge based on the undercut structure without etching the second metal layer, the limitations of the etching process on the material of the second metal film layer can be avoided. There is no need to consider the etching issues of specific materials, allowing for flexible selection of the material of the second metal film layer, thereby increasing the flexibility of air bridge preparation.

[0156] In one example, the material of the second metal film layer includes any one of the following: aluminum, tantalum, niobium, and titanium nitride.

[0157] In one example, the thickness of the second metal film layer is between 200 nm and 500 nm. For example, the thickness of the second metal film layer can be set to 400 nm, which is not limited in this embodiment of the present application. Optionally, the evaporation area of ​​the second metal film layer is the same as the preparation area.

[0158] Optionally, a second metal film layer can be deposited on the first chip product using an evaporation machine. For example, the first chip product can be placed in a vacuum coating machine to complete the evaporation of the second metal film. In some embodiments, the first metal film layer and the second metal film layer can be deposited using different evaporation machines.

[0159] Optionally, 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 in the first region, so that good superconducting contact is formed between the air bridge and the coplanar waveguide, thereby improving the performance of the chip product.

[0160] To perform ion milling, 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 to ensure its surface is clean. 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, ensuring that there is enough distance between it and the ion source. Use a sample holder or clamp to fix the sample in position. Finally, turn on the ion source and start releasing the ion beam. The ion beam will hit the sample surface, sputtering or evaporating the surface material, thereby realizing ion milling.

[0161] In some embodiments, a Kaufman ion source can be used to ionize and accelerate argon gas using thermally emitted electrons, and the argon ions bombard the sample surface to achieve an etching effect. In some embodiments, the first chip product can be placed in a coating device with an ion milling function, and the argon flow rate is set to 6 sccm (Standard Cubic Centimeter Per Minute), the ion beam voltage is set to 600 V (volts), the ion beam current is set to 35 mA (milliamperes), the acceleration voltage is set to 120 V, and the neutralization voltage is set to 40 V to perform ion milling etching on the first chip product.

[0162] In an embodiment 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 is better.

[0163] For example, referring to FIG15 , after ion milling and etching of the first chip product, the natural oxide layer 803 in the first region (i.e., the region where the bridge pier is located) is removed, and at the same time, the upper surface of the second photoresist 807 is denatured to generate a denatured photoresist 809. Then, a second metal film layer 810 is evaporated in the preparation region, and the second metal film layer 810 in the second region forms an air bridge, and the undercut structure automatically cuts off the second metal film layer 810 in the second region and the second metal film layer 810 outside the second region. In addition, this also makes the second metal film layer 810 naturally non-adhesive to the denatured photoresist 809, making it easy to remove the denatured photoresist 809, which is beneficial to improving the efficiency and quality of the debonding and obtaining a clean air bridge.

[0164] For another example, referring to FIG16 , after ion milling and etching of the first chip product, the natural oxide layer 803 in the first region (i.e., the region where the bridge pier is located) is removed, and simultaneously, the upper surface of the second positive photoresist 8082 is denatured to form a denatured photoresist 809. A second metal film layer 810 is then evaporated in the preparation region. The second metal film layer 810 in the second region forms an air bridge, and the undercut structure automatically separates the second metal film layer 810 in the second region from the second metal film layer 810 outside the second region. Furthermore, this also naturally prevents the second metal film layer 810 from adhering to the denatured photoresist 809, making the denatured photoresist 809 easier to remove.

[0165] Step 707 , dissolving the first photoresist on the first chip product to obtain a second chip product, wherein the second chip product includes an air bridge formed by a second metal film layer, and the first metal film layer outside the second area is peeled off as the first photoresist is dissolved.

[0166] The second chip product may be a chip product obtained by preparing the first chip product through an air bridge.

[0167] In one example, the first chip product can be placed in a degumming solution for cleaning to obtain a second chip product. For example, the first chip product is immersed in the degumming solution for a set period of time (e.g., 10 hours). The photoresist dissolves and separates from the substrate, while the first metal film layer and the second metal film layer outside the second region are removed from the substrate when the photoresist dissolves. The second metal film layer in the first region is connected to the coplanar waveguide and is not peeled off as the first photoresist dissolves. Therefore, only the second metal film layer in the shape of an air bridge is left, thereby forming an air bridge.

[0168] Optionally, the first photoresist and the second photoresist may be dissolved simultaneously, or the first photoresist may be dissolved alone, which is not limited in the embodiment of the present application.

[0169] In the embodiment of the present application, the first chip product can be cleaned by a degumming machine to obtain a second chip product.

[0170] In one possible implementation, when the material of the coplanar waveguide layer of the bottom circuit of the first chip product is not aluminum, if the material of the coplanar waveguide and the material of the second metal film layer are tantalum, niobium, or titanium nitride (non-aluminum), and the first metal film layer is aluminum, the first chip product can be placed in a degumming solution for cleaning and then immersed in an aluminum etching solution to ensure that the first metal film layer is completely removed (without damaging the coplanar waveguide and the second metal film layer) to obtain a second chip product.

[0171] For example, when the material of the second metal film layer includes any one of the following: tantalum, niobium, titanium nitride, and the first metal film layer is aluminum, after the first chip product is placed in a degumming solution for cleaning, the first chip product is placed in an aluminum etching solution for immersion to obtain a second chip product.

[0172] The first chip product is placed in a degumming solution to remove the photoresist on the substrate, and the metal film layer on it is also peeled off, 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 aluminum etching solution to obtain the second chip product.

[0173] In an embodiment of the present application, the aluminum etching solution may include any of the following: a mixture of phosphoric acid, nitric acid, and acetic acid. This allows for selective etching of metallic aluminum, effectively removing the first metal film layer without damaging metals such as tantalum, niobium, and titanium nitride, and exhibiting high selectivity. If the first metal film layer is aluminum, a small amount of aluminum shavings may remain during the stripping process. After debonding, soaking in the aluminum etching solution can effectively remove the remaining aluminum shavings without damaging other structures. In an embodiment of the present application, the air bridge is either a fully enclosed air bridge or a discrete air bridge.

[0174] 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.

[0175] For example, referring to FIG. 17 , after the first photoresist 804 on the first chip product is dissolved, only the second metal film layer 810 in the second region is left, and the second metal film layer 810 in the second region forms an air bridge.

[0176] To sum up, in the scheme shown in the embodiment of the present application, in the process of preparing the air bridge, after the bridge support structure is constructed by the first photoresist, the first metal film layer is first evaporated, and then the second photoresist is applied. On this basis, the second photoresist and the first metal film layer in the second area are removed, so that the second metal film layer can be directly distilled on the bridge support structure to construct the air bridge. Finally, the first photoresist is dissolved, and the second photoresist and the second metal film layer outside the second area can be peeled off to obtain a clean air bridge. In this way, isolation is formed between the first photoresist structure and the second photoresist by the first metal film layer, which can prevent the two layers of photoresist from producing a cross-linking reaction due to the principle of like dissolves like, breaks through the matching restrictions of the photoresists, and allows the preparation personnel to flexibly match the first photoresist and the second photoresist, thereby improving the flexibility of photoresist matching during the preparation of the air bridge, and further improving the flexibility of air bridge preparation.

[0177] Furthermore, the first photoresist undergoes the exposure and development process again along with the second photoresist. However, protected by the first metal film layer, the resulting bridge structure is protected from the effects of subsequent exposure, preventing dissolution of the bridge structure by the developer during the second development process. This ensures the quality of the bridge structure, thereby improving the quality of the air bridge, which in turn contributes to improved chip product manufacturing quality and performance. Furthermore, the bridge structure, protected by the first metal film layer, allows the air bridge to be exposed to white light during fabrication, enabling unrestricted measurement of the air bridge (e.g., the bridge structure) during fabrication.

[0178] Furthermore, by dissolving the first photoresist, the useless second metal film layer can be stripped away, retaining the useful second metal film layer (i.e., the air bridge) within the second region without etching the second metal film layer. This effectively improves the ease and efficiency of stripping the useless second metal film layer, thereby facilitating improved air bridge fabrication efficiency. Furthermore, since there is no need to etch the second metal film layer, the material restrictions imposed by the etching process on the second metal film layer are avoided, making any metal material that can be used to fabricate an air bridge applicable. This increases the flexibility of the second metal film layer and, in turn, effectively improves the flexibility of air bridge fabrication.

[0179] Based on the embodiment shown in FIG7 above, please refer to FIG18, which shows a flow chart of a chip product manufacturing method provided by another embodiment of the present application. As shown in FIG18, the chip product manufacturing method may include the following steps:

[0180] Step 701: Apply a first photoresist on a first chip product.

[0181] Step 702 , remove the first photoresist in the first area on the first chip product to obtain a bridge support structure for constructing the bridge body of the air bridge. The first area is the area occupied by the bridge piers of the air bridge on the first chip product, and the bridge support structure is composed of the first photoresist.

[0182] Step 703: vapor-deposit a first metal film layer on the first chip product.

[0183] Step 704: Apply a second photoresist on the first chip product.

[0184] Steps 701 to 704, and the following steps 706 to 707 are the same as those described in the above embodiment. For matters not described in the embodiment of this application, please refer to the above embodiment and will not be repeated here.

[0185] Step 705a: exposing and developing the first chip product after coating the second photoresist to remove the second photoresist in the second area to obtain a processed first chip product.

[0186] Optionally, an ultraviolet exposure machine or a laser direct writing device may be used to expose the first chip product to remove the second photoresist in the second area.

[0187] For example, the first chip product is first placed 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 exposed second photoresist in the second area, retaining the required pattern, such as an arch structure.

[0188] Step 705b: etching the first chip product to remove the first metal film layer in the second region.

[0189] Optionally, the first metal film layer in the second region may be etched to remove the first metal film layer in the second region.

[0190] For example, the etching liquid is added to the etcher, the equipment parameters are adjusted, and then the first chip product is placed in the etcher for etching operation. Common etching methods include wet etching liquid and dry etching liquid. Wet etching liquid refers to the use of liquid solutions, such as acidic or alkaline solutions, to dissolve or erode materials during the etching process. Dry etching liquid refers to the use of gas or plasma to erode materials during the etching process, rather than using liquid solutions.

[0191] After etching, the remaining first photoresist in the second region forms a bridge structure. Optionally, after etching, the remaining first metal film layer also forms an undercut structure. For example, after etching, the remaining first metal film layer outside the second region and the second photoresist form an undercut structure at the edge of the first region. This facilitates the peeling of the photoresist and the first metal layer, thereby facilitating the peeling effect and improving the quality of the air bridge.

[0192] 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.

[0193] In an embodiment of the present application, the first chip product can be wet-etched with an etchant corresponding to the first metal film layer to remove the first metal film layer in the second region. The etchant can be an etchant corresponding to the first metal film layer. For example, if the first metal film layer is aluminum, the etchant can be an aluminum etchant. Alternatively, if the first metal film layer is chromium (Cr), the etchant can be a chromium etchant. This allows the first metal film layer in the second region to be completely removed.

[0194] In one possible implementation, the first metal film layer can be etched by a developer. In some embodiments, if the first metal film layer is aluminum, during the development process, since aluminum also reacts with an alkaline developer (such as MF319 developer), the second photoresist and the first metal film layer can be removed simultaneously by controlling the development time. By appropriately controlling the process, the etching step of this solution can also be omitted. Alternatively, for aluminum, to ensure that the first metal film layer is completely removed, the developer can be used followed by an aluminum etchant for further removal.

[0195] In one example, when the second photoresist includes a first positive photoresist and a second positive photoresist, step 704 may further include the following:

[0196] 1. Apply a first positive photoresist on a first chip product.

[0197] The first positive photoresist is a non-photosensitive positive photoresist. The non-photosensitive positive photoresist is not affected by exposure, but dissolves in the developer. Its dissolution rate can be adjusted by the baking temperature. The higher the baking temperature, the slower the dissolution rate, which is conducive to constructing the undercut structure.

[0198] Optionally, the first positive photoresist may be any one of the following: PMGI SF3, LOR 10B.

[0199] The coating range of the first positive photoresist is the same as the preparation area. The thickness of the first positive photoresist can be set and adjusted according to actual use requirements, and this embodiment of the application does not limit this.

[0200] Exemplarily, the thickness of the first positive photoresist is not less than the thickness of the second metal film layer to facilitate stripping of the useless second metal film layer. For example, the thickness of the first positive photoresist is between 0.5 microns and 1.5 microns, such as 1 micron or 0.5 micron.

[0201] Optionally, after coating the first positive photoresist on the first chip product, baking can be performed to solidify the first positive photoresist, such as baking on a hot plate at 110 degrees Celsius for 60 seconds after coating the first positive photoresist on the first chip product.

[0202] 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.

[0203] 2. Apply a second positive photoresist on the first chip product after applying the first positive photoresist.

[0204] The second positive photoresist is a photosensitive positive photoresist. Optionally, the second positive photoresist can be any one of the following: nLof2070, AZ5214, and E3510.

[0205] The coating range of the second positive photoresist is the same as the preparation area. The thickness of the second positive photoresist can be set and adjusted according to actual use requirements, and this embodiment of the application does not limit this.

[0206] Optionally, the thickness of the second positive photoresist is not less than that of the first positive photoresist. This can prevent the second positive photoresist from being easily stripped by the first positive photoresist and facilitate stripping of the second metal film layer. For example, the thickness of the second positive photoresist is greater than 3 microns, such as 3.3 μm.

[0207] Optionally, after coating the second positive photoresist on the first chip product, baking may be performed to solidify the second positive photoresist, such as baking on a hot plate at 110 degrees Celsius for 60 seconds after coating the second positive photoresist on the first chip product.

[0208] Optionally, the above step 705a may further include the following content:

[0209] 1. Expose the second photoresist in the second area.

[0210] In the embodiment of the present application, since the second photoresist is a photosensitive positive photoresist, the second photoresist in the second area can be exposed using an ultraviolet exposure machine or a laser direct writing device, and the second photoresist in the exposed area will be removed after development.

[0211] 2. Develop the first chip product using a developer corresponding to the second positive photoresist to remove the first and second positive photoresists in the second region, and form an undercut structure at the edge of the remaining first positive photoresist to obtain a processed first chip product.

[0212] In an embodiment of the present application, after removing the first positive photoresist and the second positive photoresist in the second area, a large inverted trapezoidal structure will be formed, and a small undercut structure will be formed at the edge of the remaining first positive photoresist. The undercut structure makes it easier to strip the photoresist.

[0213] The first positive photoresist also dissolves in the developer corresponding to the second positive photoresist. In the embodiment of the present application, the first positive photoresist has a higher dissolution rate in the developer for the exposed second positive photoresist. Therefore, in the same amount of time, the first positive photoresist will dissolve more, which can be used to form a good undercut structure. In addition, the thickness of the first positive photoresist is greater than the thickness of the second metal film layer to facilitate stripping. At the same time, the thickness of the first positive photoresist is less than the thickness of the second positive photoresist to prevent stripping of the second positive photoresist. The second photoresist is usually thicker, which makes it less likely to be stripped by the first positive photoresist on the one hand, and can better strip the second metal film layer on the other hand.

[0214] In the embodiments of the present application, the use of first and second positive photoresists of different thicknesses facilitates alignment of the photolithographic pattern, thereby reducing alignment errors. Furthermore, a thinner first positive photoresist facilitates high-resolution exposure, resulting in a more detailed pattern and improved air bridge quality. Furthermore, by combining the positive photoresists, the photoresist in the exposed area is removed to form an inverted trapezoidal undercut structure, which facilitates the removal of air bridges (unwanted material), thereby improving the quality of the chip product.

[0215] In one example, when the second photoresist is a negative photoresist, step 705a may further include the following:

[0216] 1. Expose the second photoresist outside the second area.

[0217] Since the second photoresist is a negative photoresist, that is, the photoresist in the exposed area will be retained, a UV exposure machine can be used to expose the second photoresist outside the second area, and the second photoresist in the second area will be dissolved, thereby forming an air bridge shape with an undercut structure.

[0218] Alternatively, if the second photoresist is a negative photoresist, the negative photoresist can be directly applied to the first chip product, with the application area being the same as the fabrication area. The thickness of the negative photoresist should be no less than the thickness of the second metal film layer, which facilitates stripping of the unused second metal film layer. For example, if the second metal film layer is 3 microns thick, the thickness of the negative photoresist can be greater than 3 microns, such as 4 μm.

[0219] 2. Develop the first chip product using a developer corresponding to the negative photoresist to remove the second photoresist in the second area, forming an undercut structure composed of the remaining second photoresist, and obtaining the processed first chip product.

[0220] The second photoresist in the second region can be removed by a developer corresponding to the negative photoresist, and an undercut structure can be formed at the edge of the first region.

[0221] In an 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.

[0222] In an example, the above step 705b may further include the following: wet-etching the first chip product using an etching solution corresponding to the first metal film layer to remove the first metal film layer in the second region.

[0223] Alternatively, a chemical solution, i.e., an etchant, can be used to convert the first metal film layer into a liquid compound for removal. The etchant used is an etchant corresponding to the material of the first metal film layer. In some embodiments, the first metal film layer is made of aluminum or chromium. Therefore, the etchant must be able to dissolve aluminum or chromium.

[0224] The first metal layer can effectively isolate the first photoresist from the second photoresist and can be easily removed in subsequent processes. Metal aluminum and metal chromium are materials widely used in micromachining.

[0225] To sum up, the solution shown in the embodiment of the present application removes the first metal film layer and the second photoresist, which facilitates the subsequent evaporation of the second metal film layer, thereby directly completing the preparation of the air bridge without etching, which is beneficial to reducing the difficulty of preparing the air bridge.

[0226] Step 706: vapor-deposit a second metal film layer on the first chip product.

[0227] Step 707 , dissolving the first photoresist on the first chip product to obtain a second chip product, wherein the second chip product includes an air bridge formed by a second metal film layer, and the first metal film layer outside the second area is peeled off as the first photoresist is dissolved.

[0228] To sum up, in the embodiment of the present application, by performing etching treatment on the basis of removing the second photoresist in the second area, the first metal film layer is removed more cleanly, the first photoresist in the second area is better retained, and the structural forming of the subsequently produced air bridge is more perfect, thereby improving the overall stability of the air bridge, helping 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.

[0229] In some embodiments, the solutions shown in the above embodiments of the present application can be applied to the preparation of superconducting quantum chips. For example, taking the construction of the air bridge 130 shown in Figure 1 as an example, referring to Figure 19, the technical solutions provided in the embodiments of the present application can also include the following contents.

[0230] 1. Base.

[0231] Optionally, a substrate (i.e., a substrate) with a coplanar waveguide is prepared. The substrate can be a sapphire substrate or a high-resistance silicon substrate. The thickness of the superconducting film corresponding to the coplanar waveguide is between 100 nm and 200 nm. 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 photolithography and etching processes. Most superconducting materials naturally form an oxide layer in air. For example, referring to Figure 20, substrate 101 carries coplanar waveguide 102, and a natural oxide layer 103 is formed on coplanar waveguide 102.

[0232] 2. Spin-coat the first photoresist.

[0233] Alternatively, a first photoresist is spin-coated on the above-mentioned substrate. The photoresist can be a positive photoresist or a negative photoresist. Alternatively, the positive photoresist has SPR220 or S1813, requiring the first photoresist to have a reflow property to form an arched bridge structure. For example, with reference to Figure 20, an SPR220 type photoresist is used as an example, and a SPR220 type photoresist 104 with a thickness of 3.3 μm can be spin-coated on substrate 101 at a speed of 3000 rpm (Revolutions Per Minute).

[0234] 3. Photolithography bridge pier area.

[0235] The first photoresist can be exposed using a UV exposure machine or laser direct writing equipment. If the first photoresist is a positive-tone photoresist, the exposed area corresponds to the area where the bridge piers are located (i.e., the first area); if the first photoresist is a negative-tone photoresist, the exposed area corresponds to the area outside the bridge piers. After development, the photoresist in the area where the bridge piers are located is removed.

[0236] For example, referring to FIG20 , in the case of using 320 mJ (megajoule) / cm 2 After the SPR220 photoresist is exposed to a certain dose, it is developed with MF319 developer for 50 seconds to remove the SPR220 photoresist in the first area and to photolithography the bridge pier area.

[0237] 4. Reflux.

[0238] The substrate is placed on a hot plate and heated at high temperature. Due to the reflow properties of the first photoresist, the heated first photoresist naturally flows to form an arched bridge structure. For example, referring to FIG20 , the substrate completed in step 3 is placed on a hot plate at 140°C and heated for 3 minutes to form an arched bridge structure 105. The bridge structure 105 is composed of SPR220 photoresist 104.

[0239] 5. Evaporation of sacrificial layer.

[0240] The substrate is placed in a vacuum coating apparatus to deposit a sacrificial layer. Materials for the sacrificial layer include aluminum and chromium, as these materials have specific etchants, making subsequent removal of the sacrificial layer easier without damaging the photoresist. For example, referring to Figure 21 , after depositing 25 nm of aluminum on the substrate in an electron beam evaporation apparatus, a sacrificial layer 106 composed of aluminum (i.e., the first metal film layer) is obtained.

[0241] 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 undergo high-speed rotation and baking again. A thinner sacrificial layer can tear under high-speed rotation. This second baking also increases the fluidity of the first photoresist. A too thin sacrificial layer cannot properly wrap around the bridge structure and may deform again. For example, referring to Figure 22, sacrificial layer 2201 is torn during the subsequent high-speed spin process. Due to the heat from the bridge structure during subsequent spin coating, sacrificial layer 2201 cannot effectively maintain the bridge structure, causing deformation.

[0242] There are several reasons why a sacrificial layer needs to be evaporated before spin-coating the second photoresist. Firstly, due to the similar properties of photoresists, many are soluble in each other, according to the principle of like dissolves like. The purpose of the first photoresist is to form an arched bridge structure, while 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. However, after reflow, SPR220 photoresist is soluble in commonly used photoresists such as LOR10B, PMGI SF series, nLof2070, PMMAA4, and AZ5214. If the second photoresist is directly spin-coated on top, the bridge structure formed above will be destroyed. However, by adding a sacrificial layer between the first and second photoresists, they can be isolated and thus solve this problem.

[0243] On the other hand, since the first photoresist will undergo the exposure and development process again with the second photoresist, the bridge support structure formed 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, and the sacrificial layer can protect the bridge support structure from the influence of subsequent exposure. For example, if a positive photoresist is used in the first photoresist and a positive photoresist is also used in the second photoresist, in order 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, and the prepared bridge support structure is likely to be developed away. The added sacrificial layer can also play a light-shielding role, 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.

[0244] 6. Spin-coat the second photoresist.

[0245] The second photoresist can be a positive resist or a negative resist. The ultimate goal of the second photoresist is to form a good undercut structure.

[0246] Exemplarily, the spin coating process of the second photoresist may be as follows:

[0247] Step 6-1: The second photoresist to be spin-coated is a positive photoresist composition. First, a layer of non-photosensitive positive photoresist (i.e., the first positive photoresist) is spin-coated on the substrate. Optional photoresists include PMGI SF3, PMGI SF6, or LOR 10B. Non-photosensitive positive photoresists are unaffected by exposure but dissolve in the developer. Their dissolution rate can be adjusted by the baking temperature; generally, the higher the baking temperature, the slower the dissolution rate.

[0248] Then, a layer of photosensitive positive photoresist (i.e., the second positive photoresist) is spin-coated on the substrate. Many positive photoresists can be used in conjunction with PMGI or LOR series photoresists for positive photoresist stripping, such as SPR220, S1805, S1813, etc. For example, referring to FIG23 , a PMGI SF3 type photoresist 107 with a thickness of approximately 0.5 μm is first spin-coated on the substrate at a rotation speed of 1000 rpm multiple times, and then baked on a hot plate at 110° C. for 60 seconds. Then, a layer of SPR220 type photoresist 104 with a thickness of approximately 3.3 μm is spin-coated on the substrate at a rotation speed of 3000 rpm, and then baked on a hot plate at 110° C. for 60 seconds. Thus, a double-layer structure consisting of PMGI SF3 type photoresist 107 and SPR220 type photoresist 104 is obtained.

[0249] The spin coating process of the second photoresist can also be as follows:

[0250] In 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 (i.e., the second metal film layer). Optional photoresists include nLof2070, AZ5214 (negative photoresist), and E3510. For example, referring to FIG24 , after spin-coating nLof2070 negative photoresist 108 with a thickness of approximately 4 μm on the substrate at 5000 rpm, the substrate is then baked on a 110°C hotplate for 60 seconds to obtain a single-layer structure composed of nLof2070 negative photoresist 108.

[0251] 7. Photoetch the shape of the air bridge.

[0252] The air bridge shape refers to the shape of the air bridge, which is formed by the remaining first photoresist in the second area and the blank first area.

[0253] For example, when the second photoresist is a positive photoresist, the photolithography process of the air bridge shape may be as follows:

[0254] In step 7-1, the air bridge area (including the bridge body and pier area, i.e., the aforementioned second area) is exposed using a UV exposure machine or laser direct writing equipment. Since the second photoresist is a positive photoresist, the second photoresist in the exposed area will be removed after development, and thus the second photoresist above the air bridge area will be removed. For example, referring to FIG. 25 , since the PMGI SF3 photoresist 107 dissolves faster in the developer than the unexposed SPR220 photoresist 104, the PMGI SF3 photoresist 107 below the second layer of SPR220 photoresist at the edge of the air bridge area dissolves more, thereby forming a hollow structure, also known as an undercut structure. The second layer of SPR220 photoresist 104 forms a trapezoidal structure after development, rather than an inverted trapezoidal structure like an undercut structure. This structure, combined with the developed PMGI SF3 photoresist 107, forms an undercut structure.

[0255] In addition, the sacrificial layer 106 in the exposed area is also removed when forming this undercut structure. This is because the material Al of the sacrificial layer 106 itself can also be etched by the MF319 developer. If the development time is well controlled, the Al in the corresponding position can also be removed while the photoresist is being developed. In the case where the sacrificial layer 106 is made of Cr material, the developer cannot remove the sacrificial layer 106. The exposed sacrificial layer 106 can be etched away by the Cr etching solution after the development step. In the case where the sacrificial layer 106 is made of Al material, an etching process can also be added to further remove the sacrificial layer 106 exposed after development. Due to the influence of drilling, the sacrificial layer 106 also forms a hollow structure (i.e., an undercut structure), which is more conducive to the peeling of the air bridge. Optionally, first use 320mJ / cm 2 The second layer of SPR220 photoresist 104 is dose-exposed, and the substrate is then placed in MF319 developer for 60 seconds, and finally immersed in Al etching solution for 10 seconds (or immersed in Cr etching solution for 30 seconds) to form an undercut structure.

[0256] As for the air bridge region, since the second SPR220 photoresist layer 104, PMGI SF3 photoresist layer 107 and sacrificial layer 106 are removed, the bridge structure 105 formed by the first SPR220 photoresist layer 104 and the bridge pier region are exposed again.

[0257] For example, when the second photoresist is a negative photoresist, the air bridge lithography process may be as follows:

[0258] Step 7-2: Negative photoresist is easier to form undercut structure. Taking nLof2070 photoresist as an example, use UV exposure machine to expose the area outside the air bridge area. Since the second photoresist is negative photoresist, the second photoresist in the exposed area will be retained, and the photoresist in the area where the air bridge is located will be dissolved, thus forming an air bridge shape with undercut structure. For example, referring to Figure 26, when applying 200mJ / cm 2 After exposing the nLof2070 negative photoresist 108 to a dose of 100 nm, the substrate is baked on a 110°C hotplate for 60 seconds and then developed with MF319 developer for 2 minutes. This forms an undercut structure at the edge of the air bridge area. Similarly, the exposed Al sacrificial layer 106 is etched during the development process. An additional etching step with an Al etchant (or Cr etchant) can also be added to further remove the exposed sacrificial layer 106.

[0259] As for the air bridge region, since the nLof2070 negative photoresist 108 and the sacrificial layer 106 are removed, the bridge structure 105 formed by the first layer of SPR220 photoresist 104 and the bridge pier region are exposed again.

[0260] 8. Ion milling.

[0261] The purpose of ion milling is to remove the native oxide layer on the coplanar waveguide before evaporating the superconducting air bridge material. This allows for in-situ evaporation of the air bridge superconducting material, thereby achieving good superconducting contact between the air bridge and the coplanar waveguide. For example, referring to Figures 27 and 28 , the substrate 101 is placed in a coating apparatus equipped with ion milling capabilities. Ion milling is performed for 3 minutes using 7 sccm of argon gas at a voltage of 400 V and a beam current of 21 mA to remove the native oxide layer 103 in the bridge pier area.

[0262] As shown in Figures 27 and 28, the natural oxide layer 103 on the coplanar waveguide 102 that is not blocked by the photoresist is removed. Note that since ion milling indiscriminately bombards the surface of the substrate 101 with ions, the photoresist on the substrate 101 is also bombarded by argon ions, which causes the photoresist to denature, thereby forming a deformed photoresist 109 on the surface of the topmost photoresist layer.

[0263] 9. Vapor-depositing an air-bridge superconducting thin film (i.e., the second metal film layer).

[0264] Air bridge materials can be evaporated using electron beam evaporation, magnetron sputtering and other coating equipment to form air bridge superconducting films. The air bridge materials can be Al, Ta, Nb, TiN, etc. The thickness of the superconducting film is 200nm to 500nm.

[0265] For example, referring to Figures 29 and 30 , in this embodiment, aluminum is deposited as the first metal film layer (i.e., sacrificial layer 106) using an electron beam evaporation device, and the second metal film layer 110 is deposited using a magnetron sputtering machine. Due to the undercut structure, the superconducting metal film layer within the air bridge region is not adhered to the superconducting metal film layer outside the air bridge region, which is a necessary condition for successful debonding.

[0266] 10. Peel off.

[0267] The substrate is immersed in Remover PG stripping solution at 80°C for 10 hours. The photoresist (including the first and second photoresists) and the metal film layer above it are removed from the substrate as the photoresist dissolves. The superconducting film layer in the air bridge region, in contact with the coplanar waveguide, is not removed by the underlying first photoresist. Ultimately, only the superconducting metal in the shape of the air bridge remains, forming an air bridge.

[0268] Optionally, after soaking in the degumming solution, rinse the substrate with isopropyl alcohol and blow dry the substrate with dry nitrogen. Isopropyl alcohol dissolves in the degumming solution and can clean the degumming solution off the sample surface. Because the degumming solution is not easily volatile, while isopropyl alcohol is easily volatile, a nitrogen gun can be used to quickly dry the sample after cleaning. This prevents the sample from being left in a semi-wet state and absorbing some dirty particles, leaving traces, thereby maintaining the sample's cleanliness.

[0269] Alternatively, if both the coplanar waveguide material and the air bridge material are Ta, Nb, or TiN, and the sacrificial layer material is Al, the sacrificial layer can be immersed in an Al etchant after stripping to ensure complete removal of the sacrificial layer (without damaging the Ta, Nb, or TiN). For example, referring to FIG31 , after stripping, only the second metal film layer 110 connected to the coplanar waveguide 102 remains in the air bridge region. This second metal film layer 110 forms the air bridge 130 in FIG1 .

[0270] Alternatively, both discrete air bridges and fully enclosed air bridges can be prepared using the technical solutions provided in the embodiments of this application. For fully enclosed air bridges, small holes are typically designed on the bridge body, which facilitates debonding and stabilizes the air bridge structure. Taking a positive photoresist composition as an example, the preparation of a fully enclosed air bridge with holes in the bridge body is described. Referring to FIG. 32 , the embodiments of this application may further include the following:

[0271] The first six steps are the same as steps 1 to 6 above and will not be described here. Step 7 increases the bridge hole area (i.e., the area occupied by the bridge hole to be prepared), and in the process of photolithography of the air bridge shape, avoids the bridge hole area from being exposed, so that the unexposed second photoresist (i.e., the second layer of SPR220 type photoresist 104) is left on the bridge body, thereby forming a cylindrical structure for constructing the bridge hole (composed of the second layer of SPR220 type photoresist 104, the sacrificial layer 106 and the PMGI). SF3 type photoresist 107), after the air bridge material is evaporated, the air bridge material is evaporated on the cylindrical structure and is not connected to the bridge body and the bridge pier. After peeling, the cylindrical structure is peeled off, and the superconducting metal (i.e., the air bridge material) in the bridge hole area is also peeled off, and finally a bridge hole is formed. There is photoresist under the superconducting metal in the bridge hole area, and there is no other support. When immersed in the degumming liquid, the photoresist underneath is dissolved, and the superconducting metal loses its support and detaches. The bridge body is connected to the bridge pier, and the bridge pier is connected to the substrate, so the superconducting film in the middle bridge body part will not be taken away by the photoresist underneath.

[0272] For example, referring to FIG33 , by adopting the technical solutions provided in the embodiments of the present application, a plurality of clean discrete air bridges 3301 can be prepared on a substrate. For another example, referring to FIG34 , by adopting the technical solutions provided in the embodiments of the present application, a plurality of clean all-inclusive air bridges 3401 can also be prepared on a substrate, each of the all-inclusive air bridges 3401 having bridge holes on the bridge body.

[0273] The beneficial effects of this application are at least as follows:

[0274] 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 the method provided in this application without the need to develop an additional corresponding etching process.

[0275] 2. Compared with the etching method for preparing air bridges, this application can effectively avoid the problem of residual denatured photoresist during stripping.

[0276] 3. This application relaxes the restrictions on photoresist. By introducing a sacrificial layer, positive photoresist and negative photoresist can be flexibly used to prepare air bridges.

[0277] 4. By introducing a sacrificial layer, the process results can be monitored after each step without being affected by the white light environment.

[0278] Please refer to Figure 35, which is a schematic diagram of a chip product preparation system provided in one embodiment of the present application. The chip product preparation system can be implemented as a production line device, such as for preparing an air bridge on a first chip product after obtaining the first chip product. As shown in Figure 35, the chip product preparation system includes: a coating machine 3201, a photolithography machine 3202, a vapor deposition machine 3204, a developer 3205, and a degumming machine 3206; wherein the photolithography machine 3202 and the developer 3205 are collectively referred to as a photolithography machine, that is, the photolithography machine includes the photolithography machine 3202 and the developer 3205.

[0279] The coating machine 3201 is used to apply a first photoresist on the first chip product;

[0280] The photoresist is configured to remove the first photoresist in a first area on the first chip product to obtain a bridge support structure for constructing a bridge body of an air bridge, wherein the first area indicates an area occupied by a bridge pier of the air bridge on the first chip product, and the bridge support structure is formed by the first photoresist;

[0281] The evaporation machine 3204 is used to evaporate a first metal film layer on the first chip product;

[0282] The coating machine 3201 is used to apply a second photoresist on the first chip product;

[0283] The photoresist is configured to remove the second photoresist in a second area on the first chip product and the first metal film layer in the second area, wherein the second area includes the bridge structure and the bridge pier;

[0284] The evaporation machine 3204 is used to evaporate a second metal film layer on the first chip product;

[0285] The stripping machine 3206 is used to dissolve the first photoresist on the first chip product to obtain a second chip product. The second chip product includes the air bridge composed of the second metal film layer. The first metal film layer outside the second area is peeled off as the first photoresist is dissolved.

[0286] In a possible implementation, the chip product preparation system further includes: an etcher 3203 .

[0287] The photolithography machine 3202 and the developer 3205 are used to expose and develop the first chip product after the second photoresist is applied, so as to remove the second photoresist in the second area to obtain a processed first chip product;

[0288] The etcher 3203 is used to etch the processed first chip product to remove the first metal film layer in the second area.

[0289] In a possible implementation, the etcher 3203 is configured to wet-etch the processed first chip product using an etching solution corresponding to the first metal film layer to remove the first metal film layer in the second region.

[0290] 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;

[0291] The coating machine 3201 is used to coat the first positive photoresist on the first chip product;

[0292] The coating machine 3201 is used to coat the second positive photoresist on the first chip product after the first positive photoresist is coated;

[0293] The photolithography machine 3202 is used to expose the second photoresist in the second area;

[0294] The developing machine 3205 is used to develop the first chip product using a developer corresponding to the second positive photoresist to remove the first positive photoresist and the second positive photoresist in the second area, and to form an undercut structure at the edge position of the remaining first positive photoresist to obtain the processed first chip product.

[0295] In another possible implementation, the first metal film layer and the second metal film layer may be evaporated by different evaporation machines.

[0296] 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.

[0297] In a possible implementation, the second photoresist is a negative photoresist;

[0298] The photolithography machine 3202 is used to expose the second photoresist outside the second area;

[0299] The developer 3205 is used to develop the first chip product using a developer corresponding to the negative photoresist to remove the second photoresist in the second area, forming an undercut structure composed of the remaining second photoresist, and obtaining the processed first chip product.

[0300] In a possible implementation, the thickness of the negative photoresist is not less than the thickness of the second metal film layer.

[0301] In a possible implementation, after etching, the remaining first metal film layer forms an undercut structure.

[0302] In a possible implementation, the material of the first metal film layer includes any one of the following: metal aluminum and metal chromium.

[0303] In a possible implementation, the thickness of the first metal film layer is not less than 25 nm.

[0304] 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 in the first region.

[0305] In one possible implementation, the etcher 3203 is used to place the first chip product in an aluminum etching solution for immersion after the first chip product is placed in a degumming solution for cleaning when the material of the second metal film layer includes any one of the following: tantalum, niobium, and titanium nitride, and the first metal film layer is aluminum, so as to obtain the second chip product.

[0306] In a possible implementation, the air bridge includes any one of the following: an all-inclusive air bridge and a discrete air bridge.

[0307] In a possible implementation, the second chip product is used to prepare a superconducting quantum chip; or, the second chip product is a superconducting quantum chip.

[0308] Optionally, the chip product preparation 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, to control the coating machine 3201, photolithography machine 3202, etcher 3203, evaporation machine 3204, developer 3205 and degumming machine 3206, etc.

[0309] Optionally, the production line equipment also includes a power supply for supplying power to electrical equipment such as control chips, glue coating machine 3201, photolithography machine 3202, etcher 3203, evaporation machine 3204, developer 3205 and glue stripping machine 3206.

[0310] Optionally, the various devices corresponding to the chip product preparation system are spatially connected via a conveyor belt, or the movement of the prepared objects (such as the first chip product mentioned above) between the various devices is completed based on a robotic arm.

[0311] Optionally, the production line equipment further 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 chip product preparation method.

[0312] To sum up, in the solution shown in the embodiment of the present application, in the process of preparing the air bridge, the first photoresist is first coated on the first chip product by the coating machine 3201, and then the first photoresist is photolithographically operated by the photolithography machine 3202, and then reflowed to obtain a bridge support structure for constructing the bridge body of the air bridge. On this basis, the first chip product is evaporated by the evaporation machine 3204 to obtain a first metal film layer, and the second photoresist is continued to be 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 liquid, the subsequent etching operation of the etcher 3203 is facilitated without damaging the photoresist. Moreover, since the first metal film layer is between the two layers of photoresist, the two layers of photoresist are prevented from producing a cross-linking reaction due to the principle of like dissolves like. The cleaning action is completed by the developer 3205 and the stripper 3206. Moreover, when the first photoresist undergoes the exposure and development process again along with the second photoresist, the formed bridge structure is protected by the first metal film layer from the influence of subsequent exposure, thereby 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.

[0313] In addition, the solution shown in the embodiment of the present application also reduces the process steps and improves the yield and processing efficiency.

[0314] Please refer to Figure 36, which is a schematic diagram of an application scenario of a solution provided by an embodiment of the present application. As shown in Figure 36, this application scenario can be implemented as a superconducting quantum computing platform, which includes: a quantum computing device 361, a dilution refrigerator 362, a control device 363, and a computer 364.

[0315] Quantum computing device 361 is a circuit that operates on physical qubits. Quantum computing device 361 can be implemented as a quantum chip, such as a superconducting quantum chip operating near absolute zero. This quantum chip can be produced using the methods described in the aforementioned embodiments of this application. Dilution refrigerator 362 is used to provide an absolute zero temperature environment for the superconducting quantum chip.

[0316] Control device 363 controls quantum computing device 361, and computer 364 controls control device 363. For example, a pre-written quantum program is compiled into instructions by software in computer 364 and sent to control device 363 (e.g., an electronic / microwave control system). Control device 363 converts these instructions into electronic / microwave control signals and inputs them into dilution refrigerator 362, controlling the superconducting qubits at a temperature below 10 mK. The reading process is the opposite, with the read waveform being transmitted to quantum computing device 361.

[0317] In an exemplary embodiment, a computer-readable storage medium is also provided, which stores at least one computer instruction. The at least one computer instruction is executed by a processor in a chip product preparation system so that the chip product preparation system performs the above-mentioned chip product preparation method.

[0318] In one exemplary embodiment, a computer program product is also provided, comprising computer instructions stored in a computer-readable storage medium. A processor of a chip product manufacturing system reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the chip product manufacturing system to perform the aforementioned chip product manufacturing method.

[0319] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of the present application and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered merely as exemplary, and the true scope and spirit of the present application are indicated by the claims.

[0320] It should be understood that the present application is not limited to the exact structures 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, the method comprising: Applying a first photoresist on the first chip product; Removing the first photoresist in a first area on the first chip product to obtain a bridge support structure for constructing a bridge body of an air bridge, wherein the first area is an area occupied by a bridge pier of the air bridge on the first chip product, and 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 in a second area on the first chip product and the first metal film layer in the second area, wherein the second area includes the bridge support structure and the bridge pier; Vapor depositing a second metal film layer on the first chip product; The first photoresist on the first chip product is dissolved to obtain a second chip product, wherein the second chip product comprises the air bridge formed by the second metal film layer, and the first metal film layer outside the second area is peeled off as the first photoresist is dissolved.

2. The method according to claim 1, wherein: The removing the second photoresist in the second area on the first chip product and the first metal film layer in the second area includes: exposing and developing the first chip product after coating the second photoresist to remove the second photoresist in the second area to obtain a processed first chip product; The processed first chip product is etched to remove the first metal film layer in the second region.

3. The method according to claim 2, wherein: The etching of the processed first chip product to remove the first metal film layer in the second region includes: The processed first chip product is wet-etched using an etching solution corresponding to the first metal film layer to remove the first metal film layer in the second area.

4. The method according to any one of claims 2 to 3, wherein: 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; Applying the second positive photoresist on the first chip product after applying the first positive photoresist; The exposing and developing the first chip product after coating the second photoresist to remove the second photoresist in the second area to obtain a processed first chip product, comprising: exposing the second photoresist in the second region; 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 in the second area, and an undercut structure is formed at the edge position of the remaining first positive photoresist to obtain the processed first chip product.

5. The method according to claim 4, wherein: 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.

6. The method according to any one of claims 2 to 3, wherein: The second photoresist is a negative photoresist; The exposing and developing the first chip product after coating the second photoresist to remove the second photoresist in the second area to obtain a processed first chip product, comprising: exposing the second photoresist outside the second area; The first chip product is developed using a developer corresponding to the negative photoresist to remove the second photoresist in the second region, forming an undercut structure composed of the remaining second photoresist, and obtaining the processed first chip product.

7. The method according to claim 6, wherein: The thickness of the negative photoresist is not less than the thickness of the second metal film layer.

8. The method according to any one of claims 2 to 7, wherein: After etching, the remaining first metal film layer forms an undercut structure.

9. The method according to any one of claims 1 to 8, wherein: The material of the first metal film layer includes any one of the following: metal aluminum and metal chromium.

10. The method according to any one of claims 1 to 9, wherein: The thickness of the first metal film layer is not less than 25 nm.

11. The method according to any one of claims 1 to 10, wherein: 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 in the first region.

12. The method according to any one of claims 1 to 11, wherein: The step of dissolving the first photoresist on the first chip product to obtain a second chip product includes: When the material of the second metal film layer includes any one of the following: tantalum, niobium, titanium nitride, and the first metal film layer is aluminum, after the first chip product is placed in a degumming solution for cleaning, the first chip product is placed in an aluminum etching solution for immersion to obtain the second chip product.

13. The method according to any one of claims 1 to 12, wherein: The air bridge includes any one of the following: a fully enclosed air bridge and a discrete air bridge.

14. The method according to any one of claims 1 to 13, wherein: 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, the system comprising: Glue engraving machine, glue coating machine, evaporation machine and glue stripping machine, the glue engraving machine includes a photolithography machine and a developer; The coating machine is used to coat the first photoresist on the first chip product; The photoresist is used to remove the first photoresist in a first area on the first chip product to obtain a bridge support structure for constructing a bridge body of an air bridge, wherein the first area is used to indicate an area occupied by a bridge pier of the air bridge on the first chip product, and the bridge support structure is formed by the first photoresist; The evaporation machine is used to evaporate a first metal film layer on the first chip product; The coating machine is used to coat the second photoresist on the first chip product; The photoresist is used to remove the second photoresist in the second area on the first chip product and the first metal film layer in the second area, wherein the second area includes the bridge structure and the bridge pier; The evaporation machine is used to evaporate a second metal film layer on the first chip product; The stripping machine is used to dissolve the first photoresist on the first chip product to obtain a second chip product. The second chip product includes the air bridge formed by the second metal film layer. The first metal film layer outside the second area is peeled off as the first photoresist is dissolved.

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