Method for preparing microstructure by photoetching-electroplating-assembling process

Abstract

The invention provides a method for preparing a microstructure by a photoetching-electroplating-assembling process, and provides a new manufacturing method for realizing heterogeneous processing of various materials. The method comprises the following steps: designing a microstructure according to material selection of a process and a layer height processing rule; forming a main body part of the microstructure through a photoetching-electroplating process based on the designed microstructure; wherein in the process of forming the main body part of the microstructure, a reserved position of the assembly structure is formed, and the assembly structure is implanted into the reserved position; the thickness of the assembly structure is 90 to 100 [mu] m; and the cross sectional area of the assembly structure is 0.04 mm < 2 > to 400 mm < 2 >.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microstructure processing technology, and in particular to a method for preparing microstructure by lithography-plating-assembly process. BACKGROUND

[0002] Microstructure processing technology is a commonly used device manufacturing technology in the field of MEMS (Micro Electro Mechanical System), and often uses micro-nano processing technology method in the semiconductor industry. These processes include manufacturing processes such as thin film growth, lithography, etching, plating, laser processing, wet etching, and bonding. MEMS devices often have certain three-dimensional structural features, so the representative micro-processing technology includes LIGA, deep etching, wafer bonding, and other processes that have been the main way to form three-dimensional structural features.

[0003] After years of technical accumulation and development, MEMS technology has the process method of forming relatively high aspect ratio structural feature devices by combining various processing technologies, but no matter whether etching or additive growth technology method is used, the process method capable of forming devices with z-direction height greater than 1 mm is still relatively few. Among the many micro-nano processing technologies, plating is a kind of electrochemical cold processing method, which can form various metal structures, such as copper, nickel, gold, tin, silver, zinc and a series of metals that can be precipitated and formed in aqueous solution. However, these metals plated cannot be controlled at will on the shape of the substrate, and must be formed by non-conductive patterns to form the required pattern. SUMMARY

[0004] The embodiment of the present application provides a method for preparing microstructure by lithography-plating-assembly process, which provides a new manufacturing method for realizing heterogeneous processing of various materials.

[0005] The present application provides a method for preparing microstructure by lithography-plating-assembly process, comprising: designing a microstructure according to the material selection and layer height processing rules of the process; forming a main part of the microstructure by a lithography-plating process based on the designed microstructure; wherein the process of forming the main part of the microstructure also includes forming a reserved position of an assembly structure, and implanting the assembly structure into the reserved position.

[0006] In one embodiment, the assembly structure is a heterogeneous structure; and the assembly structure comprises at least one of metal, ceramic and polymer.

[0007] In one embodiment, the main part is a plated metal.

[0008] In one embodiment, the implanting of the assembly structure into the reserved position comprises: An automatic identification point glue machine is used to automatically identify the reserved position of the assembly structure, and move the glue nozzle of the point glue gun to the center of the reserved position of the assembly structure to perform point glue; An automatic identification point glue machine is used to automatically identify the reserved position of the assembly structure, and move the glue nozzle of the point glue gun to the center of the reserved position of the assembly structure to perform point glue;

[0009] In an embodiment, the main body part of the microstructure is formed based on the designed microstructure through a photo-etching and electroplating process, comprising: Step 01: Obtain a wafer as a substrate, sputter and grow an adhesion layer on the surface of the wafer based on the designed structure, and form a conductive seed layer on the adhesion layer; Step 02: Coating photoresist on the surface of the conductive seed layer, and performing photoetching based on the designed structure to obtain a photoetching pattern of the microstructure; Step 03: Electroplating a metal material on the wafer with the photoetching pattern; Step 04: After controlling the thickness of the metal material and photoresist on the surface of the wafer to the target thickness through a planarization process, a first layer structure of the microstructure is obtained; Step 05: Repeat steps 02-04 on the first layer structure until the main body part of the microstructure is obtained.

[0010] In an embodiment, after the main body part of the microstructure is formed based on the designed microstructure through a photo-etching and electroplating process, further comprising: removing the sacrificial layer of the main body part to obtain the final microstructure.

[0011] In an embodiment, the removal of the sacrificial layer of the main body part to obtain the final microstructure comprises: Soak the microstructure in a photoresist removal solvent to remove the photoresist sacrificial layer; After removing the sacrificial layer, use dilute nitric acid to etch and remove the seed layer inside the microstructure and the wafer; Use a hydrofluoric acid solution to etch and remove the adhesion layer of the microstructure.

[0012] In an embodiment, after the removal of the sacrificial layer of the main body part to obtain the final microstructure, further comprising: Remove the substrate; or Wafer dicing is performed on the substrate to form independent devices from the entire wafer device.

[0013] In one embodiment, the microstructure comprises a multi-layer structure, wherein the height of each layer structure is 100 μm or 50 μm.

[0014] In one embodiment, the forming of the reserved positions of the assembly structures and the implanting of the assembly structures into the reserved positions comprises: in the process of forming the main part of the microstructure, the reserved positions of the assembly structures of different levels are formed, and all the assembly structures are implanted into the corresponding reserved positions; the thickness of the assembly structure is 90-100 μm; the cross-sectional area of the assembly structure is 0.04 mm 2 -400 mm 2 .

[0015] From the above technical solutions, the present application has the following advantages: The present application provides a method for preparing a microstructure by using a photo-etching-plating-assembly process, which comprises: designing a microstructure according to the material selection and layer height processing rules of the process; forming a main part of the microstructure by using a photo-etching-plating process based on the designed microstructure; wherein, in the process of forming the main part of the microstructure, the reserved positions of the assembly structures are formed, and the assembly structures are implanted into the reserved positions. By using the auxiliary micro-processing process on the wafer substrate and the sequential combination of photo-etching, plating and assembly, the microstructure morphology of the combination of heterogeneous materials such as metal and metal, metal and ceramic, metal and polymer, metal and ceramic and polymer can be finally formed. The present method is a brand-new microstructure forming process, which can be processed in the wafer processing mode, and the plating metal is used as the main structure to realize the heterogeneous processing combination of metal and ceramic, polymer and other materials, and can provide a new manufacturing method for heterogeneous microstructures. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0017] Figure 1 is a flow chart of a microstructure manufacturing method provided by an embodiment of the present application; Figure 2 is a flow chart of a microstructure manufacturing method provided by another embodiment of the present application; Figure 3 is a first layer structure schematic diagram of a micro coaxial transmission line completed by using the microstructure manufacturing method provided by an embodiment of the present application; Figure 4It is the schematic diagram of the two-layer photoetching master and the heterogeneous structure reserved position of the micro coaxial transmission line prepared by the manufacturing method of the micro structure provided by an embodiment of the present application; Figure 5 It is the schematic diagram of the reserved assembly position point adhesive of the micro coaxial transmission line prepared by the manufacturing method of the micro structure provided by an embodiment of the present application; Figure 6 It is the schematic diagram of the reserved assembly ceramic structure and the adhesive curing of the micro coaxial transmission line prepared by the manufacturing method of the micro structure provided by an embodiment of the present application; Figure 7 It is the schematic diagram of the two-layer metal structure of the micro coaxial transmission line prepared by the manufacturing method of the micro structure provided by an embodiment of the present application; Figure 8 It is the schematic diagram of the two-layer metal structure after planarization of the micro coaxial transmission line prepared by the manufacturing method of the micro structure provided by an embodiment of the present application; Figure 9 It is the schematic diagram of the five-layer structure of the micro coaxial transmission line prepared by the manufacturing method of the micro structure provided by an embodiment of the present application; Figure 10 It is the schematic diagram of the complete structure of the micro coaxial transmission line after removing the sacrifice layer prepared by the manufacturing method of the micro structure provided by an embodiment of the present application; Figure 11 It is the schematic diagram of the whole three-dimensional structure of the micro coaxial transmission line prepared by the manufacturing method of the micro structure provided by an embodiment of the present application; Figure 12 It is the schematic diagram of the internal structure of the micro coaxial transmission line prepared by the manufacturing method of the micro structure provided by an embodiment of the present application; Figure 13 It is the first layer structure schematic diagram of the magnetic core micro inductor prepared by the manufacturing method of the micro structure provided by another embodiment of the present application; Figure 14 It is the schematic diagram of the two-layer photoetching master and the heterogeneous structure reserved position of the magnetic core micro inductor prepared by the manufacturing method of the micro structure provided by another embodiment of the present application; Figure 15 It is the schematic diagram of the reserved assembly position point adhesive of the magnetic core micro inductor prepared by the manufacturing method of the micro structure provided by another embodiment of the present application; Figure 16 It is the schematic diagram of the reserved assembly ceramic structure and the adhesive curing of the magnetic core micro inductor prepared by the manufacturing method of the micro structure provided by another embodiment of the present application; Figure 17 It is the schematic diagram of the two-layer metal structure of the magnetic core micro inductor prepared by the manufacturing method of the micro structure provided by another embodiment of the present application; Figure 18is a schematic view of a planarized magnetic core micro-inductor two-layer metal structure prepared by a manufacturing method using a microstructure according to another embodiment of the present application; Figure 19 is a schematic view of a magnetic core micro-inductor assembled magnetic core structure and three-layer planarization completed by a manufacturing method using a microstructure according to another embodiment of the present application; Figure 20 is a schematic view of a five-layer structure of a magnetic core micro-inductor prepared by a manufacturing method using a microstructure according to another embodiment of the present application; Figure 21 is a schematic view of a complete structure of a magnetic core micro-inductor after removing a sacrificial layer by a manufacturing method using a microstructure according to another embodiment of the present application; Figure 22 is a schematic view of a whole magnetic core micro-inductor three-dimensional structure prepared by a manufacturing method using a microstructure according to another embodiment of the present application.

[0018] Reference signs: 1, first electroplated metal layer; 2, photoresist; 3, support structure; 4, second layer structure; 5, third layer structure; 6, fourth layer structure; 7, fifth layer structure; 8, wafer; 9, sacrificial layer; 21, substrate; 22, first sacrificial layer; 23, first electroplated metal layer; 24, die-attaching adhesive; 25, ceramic structure; 26, second electroplated metal layer; 27, third electroplated metal layer; 28, magnetic core structure; 29, fourth electroplated metal layer; 30, fifth electroplated metal layer. DETAILED DESCRIPTION

[0019] The embodiment of the present application provides a method for preparing a microstructure by a photoetching-electroplating-assembly process, and provides a new manufacturing method for realizing heterogeneous processing of various materials.

[0020] To make the purposes, features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the embodiments described below are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0021] Those skilled in the art can clearly understand the specific working processes of the system, device and unit described above for the convenience and brevity of description, and the corresponding processes in the foregoing method embodiments can be referred to, which will not be described herein.

[0022] In several embodiments provided in the present application, it should be understood that the disclosed methods, devices, electronic devices and storage media can be implemented in other ways. For example, the above-described device embodiments are only illustrative, and the division of the units is only a logical function division. In actual implementation, another division manner can be used, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0023] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place or distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0024] In addition, the functional units in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0025] When the integrated unit is realized in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a readable storage medium, including a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in the various embodiments of the present application. The aforementioned readable storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0026] The above-described embodiments are merely used to illustrate the technical solutions of the present application, but not to limit the present application; even though the above-mentioned embodiments are described in detail, those skilled in the art should understand that they can still modify the technical solutions described in the above-mentioned embodiments, or make equivalent replacements to some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

[0027] Embodiment one: The embodiment provides a method for preparing a microstructure by using a photoetching-plating-assembly process, Figure 1 is a flow chart of a method for manufacturing a microstructure according to an embodiment of the present application; as shown in the figure, the method comprises the following steps: Figure 1 Step 01: designing a microstructure according to the material selection and layer height processing rules of the process.

[0028] According to the material selection and layer height processing rules of the process, a microstructure with a multi-layer mechanism is designed by using software.

[0029] During the design process, electromagnetic simulation software such as AnsysHFSS, CST, etc. can be used to design the structure and electromagnetic function of the required microstructure. During the design process, the size, position, and implantation quantity of the assembly structure piece that needs to be assembled in the designed structure are determined by using the electromagnetic simulation software.

[0030] Step 02: forming a main part of the microstructure by using a photoetching-plating process based on the designed microstructure; wherein the process of forming the main part of the microstructure also comprises forming a reserved position of the assembly structure and implanting the assembly structure into the reserved position.

[0031] It can be understood that, during the process of forming the main part of the microstructure by using the photoetching-plating process, the reserved position of the assembly structure can be formed at the target position according to the designed microstructure. Optionally, the microstructure comprises a multi-layer structure, and the reserved position can also be multiple, and different reserved positions can be formed in the same level or different level structures, and the present application does not limit this.

[0032] Optionally, the main part is a plated metal.

[0033] Optionally, the assembly structure is a heterogeneous structure; the heterogeneous structure can be at least one of a metal, a ceramic, and a polymer.

[0034] ​The method implants the heterogeneous structure into the main part of the microstructure by using the auxiliary micro-processing process and the sequential combination of photoetching, electroplating and assembly, and finally forms the microstructure morphology of the combination of heterogeneous materials such as electroplated metal and metal, electroplated metal and ceramic, electroplated metal and polymer, metal and ceramic and polymer. The method is a brand-new microstructure forming process. In the wafer processing mode, the electroplated metal is used as the main structure, and then the heterogeneous structure is implanted by using the assembly mode, the heterogeneous processing combination of metal and ceramic, polymer and other materials is realized, and thus a new manufacturing method for the heterogeneous microstructure is provided.

[0035] Embodiment two: The embodiment provides a method for preparing a microstructure by using a photoetching-electroplating-assembly process. The manufacturing method of the main structure comprises the following steps: (1) obtaining a wafer as a substrate, sputtering and growing an adhesion layer on the surface of the wafer based on a designed structure, and forming a conductive seed layer on the adhesion layer.

[0036] Optionally, the wafer can be a silicon wafer or a wafer made of other materials, for example, a compound semiconductor material such as aluminum oxide, silicon carbide (SiC) and gallium arsenide (GaN), etc. It can also be a silicon-on-insulator (SOI) material or other new materials. Specifically, the obtained wafer is a silicon wafer, generally with a resistivity of 1 Ω / cm-10 Ω / cm, a crystal direction of 100, 110, a thickness of 500 μm-700 μm, and an attached 1 μm oxide insulating layer.

[0037] It can be understood that the seed layer is usually prepared by using a magnetron sputtering method, an adhesion layer is sputtered and grown on the surface of the wafer, and a conductive seed layer is sputtered on the adhesion layer; the conductive seed layer provides a basis for the subsequent electroplating step; wherein the adhesion layer can be a 20 nm-30 nm thick metal titanium adhesion layer, and the conductive seed layer can be a 300 nm-2000 nm thick metal copper conductive seed layer.

[0038] (2) coating photoresist on the surface of the conductive seed layer, and performing photoetching based on the designed structure to obtain a photoetching pattern of the microstructure.

[0039] Optionally, the photoresist is coated on the surface of the conductive seed layer, and the first layer photoetching according to the designed structure of the microstructure is performed to form the bottom surface of the microstructure on the substrate; the photoresist is cured, exposed and developed to obtain the photoetching pattern of the microstructure.

[0040] (3) electroplating a metal material on the wafer on which the photoetching pattern is formed.

[0041] Optionally, copper is electroplated on the wafer on which the photoetching pattern of the microstructure is formed.

[0042] (4) After the thickness of the metal material and the photoresist on the wafer surface is controlled to the target thickness by using the planarization process, a first layer structure of the microstructure is obtained.

[0043] The wafer planarization as an auxiliary process is mainly used for forming a consistent plane between the metal structure and the photoresist or between the metal structure and the assembly structure. After the thickness of the metal copper and the photoresist on the wafer surface is controlled to the target thickness by using the wafer planarization process, a first layer structure of the microstructure is obtained. The wafer planarization is usually realized by using the wafer mechanical polishing or the chemical mechanical polishing technology.

[0044] (5) Steps (2) to (4) are repeatedly performed on the first layer structure until the main part of the microstructure is obtained.

[0045] It is necessary to explain in this step that the processes of the thick photoresist lithography, the electroplating and the wafer planarization in the repeating process are basically the same as those in the above steps. Only when the photoresist pattern changes, the corresponding process parameters are adjusted according to the change of the pattern area. For example, the change of the electroplating current caused by the change of the electroplating pattern size is easy to understand in the industry.

[0046] It is necessary to explain that the multi-layer structure of the microstructure can be prepared by continuously repeating steps (2) to (4). In the process of repeating steps (2) to (4) to form different structures of the main part of the microstructure, the reserved positions of the assembly structures of different levels can be formed at the same time, and all the assembly structures are implanted into the corresponding reserved positions. It can be understood that the reserved positions of the assembly structures are not limited to the layer of the main part, that is, they can be formed in any one of the repeating processes of steps (2) to (4). The present application does not limit the reserved positions of the assembly structures and the steps of forming the reserved positions of the assembly structures.

[0047] The method for implanting the assembly structure into the reserved position is as follows.

[0048] Alternatively, the assembly structure is a heterogeneous structure; the assembly structure comprises at least one of a metal, a ceramic and a polymer. Implanting the assembly structure into the reserved position of the assembly structure can realize a complex three-dimensional structure, heterogeneous material integration or a microstructure with a higher aspect ratio.

[0049] Specifically, the implanting of the assembly structure into the reserved position of the assembly structure comprises: An automatic identification dispensing machine is used to automatically identify the reserved position of the assembly structure, and the glue nozzle of the dispensing gun is moved to the center of the reserved position of the assembly structure to perform dispensing. The automatic recognition die bonding machine is used to align the center position of the assembly structure, to suck the assembly structure by the automatic suction nozzle, to move and align the center of the reserved position of the assembly structure on the wafer, to control the reserved position or the suction nozzle to move in the vertical direction to the horizontal direction by the die bonding machine, so that the assembly structure is placed in the reserved position of the assembly structure after the dispensing and contacts the die bonding glue, the suction nozzle stops sucking the die, and the assembly structure is implanted in the reserved position of the assembly structure.

[0050] The implanting of the assembly structure into the reserved position includes implanting all assembly structures into corresponding reserved positions based on the design structure. It can be understood that the microstructure includes multiple structures that need to be assembled, and the implanting process of the microstructure can be inserted in different hierarchical structures. It is not implanted only once in step (2), that is, in the preparation process of the microstructure, according to the design structure in step (1), the manufacturing can be repeatedly and alternately performed in the way of photoetching-plating-micro assembly, which is significantly different from the traditional process that is continuously completed on a single substrate. The present application does not limit the sequence of each step.

[0051] Optionally, the height of each layer structure is 100 μm or 50 μm.

[0052] Optionally, the thickness of the assembly structure is in the range of 90-100 μm; the shape and size can be completed by laser cutting, machining and the like; and the cross-sectional area size of the assembly structure is in the range of 0.04 mm 2 400 mm 2 .

[0053] After the main part of the microstructure is formed by the photoetching-plating process based on the designed microstructure, the method further includes removing the sacrificial layer of the main part to obtain the final microstructure.

[0054] The corresponding sacrificial layer removal method is used to remove the photoresist and the seed layer structure in the process, to retain the metal structure, the assembled ceramic, other metal, polymer and the like, to obtain the final functional microstructure.

[0055] The corresponding sacrificial layer removal method includes: soaking the microstructure in a photoresist remover to remove the photoresist sacrificial layer; after removing the sacrificial layer, using dilute nitric acid to etch and remove the seed layer inside the microstructure and the wafer; using a hydrofluoric acid solution to etch and remove the adhesion layer of the microstructure. In addition to the above methods, other sacrificial layer removal methods can also be included, which are not described herein.

[0056] It is to be noted that in this step, the photoresist and seed layer used for temporary support during the microstructure manufacturing process need to be removed using specific chemical solvents or physical methods. This step allows the metal microstructure and assembled structure to be retained, thereby forming a functional microstructure composed of different materials such as heterostructures and metals.

[0057] In one embodiment, Figure 3 is a flowchart of a microstructure manufacturing method according to another embodiment of the present application. As shown in Figure 3 , the microstructure manufacturing method comprises the following steps: Step 101: Using functional software, a microstructure is designed according to the layer-by-layer processing rules of the manufacturing process.

[0058] Step 102: A mask layout for layer-by-layer processing is formed according to the designed structure, including a multi-layer metal structure plating pattern and an assembly reserved pattern.

[0059] Step 103: A wafer substrate is obtained, a metal seed layer is prepared, and a microstructure pattern is obtained by photolithography on the wafer surface.

[0060] Step 104: Metal is electroplated within the photolithography pattern to form a metal microstructure, and a planarization process is used to control the thickness of the metal and photoresist to the target thickness, thereby obtaining the first layer of the microstructure.

[0061] Step 105: Other metal layers not containing heterostructures are obtained by sequentially using photolithography, electroplating, and planarization processes.

[0062] Step 106: A metal structure layer containing an assembly reserved position is formed by photolithography.

[0063] Step 107: An assembly process using visual recognition, automatic dispensing, and automatic die bonding is used to implant the required heterostructure pieces in the reserved positions.

[0064] Step 108: A metal structure layer containing assembled heterostructures is obtained by using electroplating and planarization processes.

[0065] Step 109: Subsequent other metal layers not containing heterostructures are obtained by using photolithography, electroplating, and planarization processes. After step 109, when forming other metal layers, at least one repetition of steps 106-109 can be included to complete the assembly of the assembled heterostructures in the subsequent layers. The reserved positions for the assembly of heterostructures can be prepared according to the mask layout.

[0066] Step 110: After completing the preparation of all metal layers and the assembly of the assembled structure, the photoresist is removed to obtain the final functional hetero-integrated microstructure.

[0067] Further, after the sacrificial layer of the main body part is removed to obtain the final microstructure, further comprising: removing the substrate; or wafer dicing the substrate to form independent devices.

[0068] Further, on the basis of the embodiment, between the preparation of the insulating layer and the preparation of the seed layer, further comprising: Wafer cleaning: the wafer with the grown oxide insulating layer is sequentially cleaned by 3:1 concentrated sulfuric acid hydrogen peroxide cleaning for 15 min, 65℃ hot deionized water cleaning, and 20℃ cold deionized water cleaning, and then dried in an oven at 110℃-120℃.

[0069] Further, in the thick photoresist process, a layer of 110μm-120μm thick photoresist is spin-coated on the wafer surface; during the spin-coating process, the uniformity and consistency of the photoresist layer are ensured by adjusting the spin-coating speed and spin-coating time. Commonly used photoresist materials include AZnxt125, N226-30000P type photoresist materials.

[0070] Further, in the electroplating process, direct current or pulse electroplating is used; during the electroplating process, the plating solution temperature is controlled within the range of 20-30℃, and any one of plating solution circulation, cathode oscillation, and rotary electroplating is used to make the electroplated copper thickness uniform; commonly used electroplating solutions include sulfuric acid and copper sulfate system electroplating solutions.

[0071] Further, in the assembly process, the assembly piece is designed and processed at the beginning, and the material can be selected in multiple ways. Ceramics include aluminum oxide, aluminum nitride, silicon carbide, zirconium oxide, etc., polymers include polytetrafluoroethylene, PP, polyimide, polycarbonate, etc., other metals include various steel materials, ferromagnetic materials, rare and precious metal materials, etc., which are suitable for mechanical support and functional contribution different from the electroplated metal itself, and the thickness is generally within the range of 90-100μm, the shape and size can be completed by laser cutting, machining, etc., and the area size is generally within the range of 0.04mm 2 400mm 2 According to different device structures; for the ceramic piece adhesive, a specific adhesive needs to be used, and the amount of adhesive is designed according to the properties of the adhesive and the properties of the sacrificial layer photoresist, generally within the range of 0.000125-0.2mL, the heat treatment curing temperature is generally within the range of 50-90℃, and the time is not more than 20min, and the thickness of the cured adhesive is within the range of 2-10μm. The assembly structure in this embodiment is an aluminum oxide ceramic piece.

[0072] Further, in the wafer planarization process, the mechanical polishing method is used to polish the copper and photoresist on the wafer surface; when the thickness difference between the copper and photoresist on the wafer surface and the target thickness is 3-8 μm, the chemical mechanical polishing method is used to further planarize the wafer until the thickness of the copper and photoresist on the wafer surface reaches the target thickness. The mechanical polishing method is used to primarily planarize the wafer surface, mainly to polish and remove the copper and photoresist on the wafer surface. During the polishing process, the material thickness on the wafer surface is monitored in real time, and when the thickness difference between the copper and photoresist and the target thickness is reduced to 3-8 μm, the chemical mechanical polishing method is switched to.

[0073] Further, the sacrificial layer is removed by immersing in a stripping solvent, and the commonly used is NMP organic solvent; wherein, during the immersion process, the temperature of the stripping solvent is greater than 70 DEG C, and the immersion time is greater than 3 hours; through this step, the sacrificial layer can be effectively dissolved and removed. After removing the sacrificial layer, the seed layer inside the micro coaxial structure and the wafer is removed by etching with dilute nitric acid with a volume fraction of 3%; the adhesion layer is removed by etching with a hydrofluoric acid solution with a volume fraction of 2%. The treatment time of dilute nitric acid should be adjusted according to the actual situation to ensure that the seed layer is completely removed. Similarly, the treatment time of the hydrofluoric acid solution should also be adjusted according to the actual needs until the adhesion layer is completely removed.

[0074] Example three: The application provides a preparation method of a micro coaxial transmission line. S1, according to the material selection and layer height processing rules of the process, a micro coaxial transmission line with a multi-layer structure is designed. Optionally, the micro coaxial transmission line includes a five-layer structure, which includes a first layer to a fifth layer of metal structure, and above and below the inner conductor of the micro coaxial line, a support structure 3 is designed by an assembly method. Optionally, the support structure 3 is a ceramic structure sheet of aluminum oxide. The height of the support structure 3 is 100 μm, the size is 1 mm*0.5 mm, and the placement position is in the cavity near the port of the coaxial line, which forms an upper and lower clamping relationship with the inner conductor.

[0075] Optionally, in the design process, electromagnetic simulation software such as AnsysHFSS, CST, etc. can be used to design the structure and electromagnetic function of the required micro coaxial transmission line. In the design process, the size, position, implantation quantity, etc. of the support structure 3 sheet to be assembled in the designed structure are determined by the electromagnetic simulation software.

[0076] S2, according to the structure designed in S1, a mask layout is formed, which mainly includes each layer of electroplated metal pattern of the micro coaxial transmission line, and an assembly reserved pattern position, and the device processing is completed through the sequential combination of the seed layer preparation, wafer planarization and other auxiliary micro processes, and the main process steps of photolithography, electroplating and assembly. The specific steps are as follows.

[0077] S21: Obtain the wafer 8, and sequentially perform the seed layer preparation, thick photoresist photolithography, electroplating, wafer planarization and other process processing to obtain the first layer of metal microstructure of the micro coaxial transmission line; refer to Figure 3 .

[0078] It needs to be explained in this step that: (1) The wafer 8 can be a silicon wafer or a wafer of other materials. For example, it can be a compound semiconductor material such as aluminum oxide, silicon carbide (SiC) and gallium arsenide (GaN); it can also be a silicon-on-insulator (SOI) material or other new materials. Specifically, if the obtained wafer 8 is a silicon wafer, it is generally preferred to have a resistivity of 1 Ω / cm-10 Ω / cm, a crystal direction of 100, 110, a thickness of 500 μm-700 μm, and an attached 1 μm oxide insulating layer.

[0079] (2) The seed layer preparation is an auxiliary process in the manufacturing method, and a magnetron sputtering method is usually used to sputter and grow an adhesion layer on the surface of the wafer 8, and a conductive seed layer is sputtered on the adhesion layer; the conductive seed layer provides a basis for the subsequent electroplating step; wherein the adhesion layer is a 20 nm-30 nm thick titanium adhesion layer, and the conductive seed layer is a 300 nm-2000 nm thick copper conductive seed layer.

[0080] (3) The photoresist 2 is coated on the surface of the conductive seed layer, and the first layer of photolithography of the designed structure of the micro coaxial transmission line is formed on the substrate to form the bottom surface of the micro coaxial outer conductor; the photoresist 2 is cured, exposed and developed to obtain the microstructure photolithography pattern.

[0081] (4) The electroplating process is a core process step in the manufacturing method: electroplating copper on the wafer 8 with the microstructure photolithography pattern formed.

[0082] (5) The wafer planarization is used as an auxiliary process to form a consistent plane between the metal structure and the photoresist 2 or the metal structure and the assembly structure, and the wafer planarization process is used to control the thickness of the copper on the wafer surface and the photoresist 2 to the target thickness to obtain the first layer of structure of the micro coaxial transmission line; the wafer planarization usually uses wafer mechanical polishing or chemical mechanical polishing technology to achieve.

[0083] S22: sequentially through the thick glue lithography, automatic identification point glue, automatic identification of die, electroplated copper, wafer planarization to get the second layer of metal microstructure of the ceramic structure micro coaxial transmission line attached to the assembly; reference Figures 4-6 as shown.

[0084] It needs to be explained in this step: (1) The thick glue lithography, electroplating, wafer planarization process used in this part is basically the same as that in S21 step, only when the lithography pattern changes, the corresponding process parameters are adjusted according to the change of the pattern area, for example, the change of the electroplating current caused by the change of the electroplating pattern size.

[0085] (2) Automatic identification of point glue machine can be achieved, which can automatically identify the reserved position of the ceramic structure on the wafer according to the setting, and move the glue nozzle of the point glue gun to the center of the reserved position of the ceramic structure. Through the control of the micro pump, automatic point glue is completed, the point glue amount is in the range of 0.000125~0.2mL, and the glue can use common chip structure die adhesive or similar materials.

[0086] (3) The die bonder with automatic recognition technology aligns the center position of the ceramic structure sheet, sucks up the ceramic sheet through the automatic suction nozzle, then moves and aligns the center of the reserved position of the ceramic sheet on the wafer, controls the vertical movement of the wafer or suction nozzle through the die bonder, so that the ceramic structure sheet is placed in the reserved position of the point glue and contacts the die adhesive. The suction nozzle stops sucking the sheet, the ceramic structure sheet is placed in the reserved position, and through repeated operation, the assembly of all ceramic structures on the wafer is completed, and the die adhesive curing is carried out at a temperature of 50-90℃.

[0087] S23: according to the design structure in S1, repeat and sequentially implement the seed layer deposition, thick glue lithography, copper electroplating, wafer planarization, automatic identification point glue, automatic identification die bonder and other processes in S21 and S22 to complete the third layer structure, fourth layer structure and fifth layer structure of the micro coaxial transmission line in the design; reference Figures 7-9 as shown.

[0088] It needs to be explained in this step: The processes in this step are repeated S21 and S22 process steps, only when the lithography pattern changes, the corresponding process parameters are adjusted according to the change of the pattern area, for example, the change of the electroplating current caused by the change of the electroplating pattern size, which is easy to understand in the industry.

[0089] S3: removing the photoresist sacrificial layer 9 of the micro coaxial transmission line structure, the metal copper structure body and the support structure 3 remain. The support structure 3 realized and remained by the assembly process can make the micro coaxial inner conductor obtain good suspended support, and form an internal air cavity micro coaxial structure. Refer to Figure 10

[0090] It needs to be explained in this step: This step needs to use specific chemical solvents or physical methods to remove the photoresist material and seed layer material used for temporary support structure 3 in the process of manufacturing the micro coaxial transmission line. This step makes the metal microstructure and the assembled support structure 3 remain, thereby forming a functional microstructure of the micro coaxial transmission line composed of ceramic and metal copper.

[0091] Refer to Figure 10 , Figure 11 and Figure 12 The structure of the micro coaxial transmission line includes: The transmission line body and a plurality of support structures 3; The transmission line body includes an inner conductor and an outer conductor; the outer conductor is arranged outside the inner conductor, and a cavity structure is formed between the inner conductor and the outer conductor; A plurality of support structures 3 are arranged in the cavity near the port of the micro coaxial transmission line, and a part is arranged above the inner conductor and another part is arranged below the inner conductor, and the plurality of support structures 3 and the inner conductor form an upper and lower clamping relationship to support the inner conductor.

[0092] In the preparation of the micro coaxial transmission line, a first layer structure is prepared first, and then a second layer structure is formed, wherein the first layer structure includes: A wafer 8; A metal material layer arranged on the upper surface of the wafer; A first photoresist layer arranged on the upper surface of the wafer and located on both sides of the metal material layer.

[0093] Refer to Figure 10 The outer conductor includes a first electroplated metal layer 1, and a second layer structure 4, a third layer structure 5, a fourth layer structure 6 and a fifth layer structure 7 formed in sequence on one side of the upper surface of the first electroplated metal layer 1.

[0094] Example four: The embodiment provides a preparation method of a magnetic core micro inductor, and the preparation method includes: (1) using HFSS software to design as Figure 22 ​The copper coil micro-inductor structure with a magnetic core is shown. The magnetic core in the middle of the copper coil is a Nd-Fe-B permanent magnet. The upper and lower layers of the permanent magnet are both alumina ceramic sheet structures. The magnetic core and the upper and lower ceramic sheet structures are located in the middle of the entire coil.

[0095] (2) According to the design structure in (1), a photolithography layout of the magnetic core micro-inductor is formed.

[0096] (3) A 6-inch silicon wafer with a thickness of 500 μm and a surface attached with a 1 μm oxide layer is selected. The wafer is cleaned by a mixture of concentrated sulfuric acid and hydrogen peroxide, hot deionized water, and cooled ionized water, and then dried. A 500 nm copper film is sputtered on the surface of the wafer as a seed layer.

[0097] (4) AZnXT125 photoresist is selected. The photoresist is spin-coated on the surface of the seed layer in (3) to a thickness of 115 μm, and exposed and developed according to a one-layer structure layout. A copper structure is electroplated, and a wafer planarization process is performed to form a first layer of metal microstructure of the magnetic micro-inductor, as shown in Figure 13 .

[0098] (5) AZnXT125 photoresist is selected. The photoresist is spin-coated on the surface of the first layer of metal microstructure of the magnetic core micro-inductor in (4) to a thickness of 115 μm. The photoresist is exposed and developed according to a two-layer structure layout, leaving a position for bonding the ceramic structure sheet. As shown in Figure 14 .

[0099] (6) LH-880 epoxy adhesive is selected. The adhesive is dispensed on the position for bonding the ceramic structure sheet in (5) using an automatic recognition dispensing machine, with an adhesive amount of 0.01 mL. Then, an automatic recognition adhesive bonding machine is used to pick up an alumina ceramic sheet with a size according to the design and a thickness of 100 μm, and place it on the position for dispensing the adhesive. The adhesive is cured under the conditions of 80°C and 15 min to form a 24-layer adhesive bonding structure, as shown in Figure 15 and Figure 16 .

[0100] (7) A two-layer copper structure of the magnetic core micro-inductor coil is electroplated to a thickness of 120 μm. A wafer planarization process is performed to complete the two-layer microstructure of the magnetic micro-inductor. The thickness of this layer is controlled to 100 μm by mechanical polishing, and then to 105 μm by chemical mechanical polishing. As shown in Figure 17 and Figure 18 .

[0101] (8) The process steps similar to (5), (6), and (7) are repeated to complete the third layer of metal (which can be a magnetic core structure sheet 10) structure processing of the Nd-Fe-B magnetic core and the inductor coil. As shown in Figure 19 .

[0102] (9) Repeat similar process steps (5), (6), (7), to complete the upper ceramic structure piece and the fourth layer of metal structure of the inductor coil.

[0103] (10) Repeat similar process step (4), to complete the entire five-layer structure of the magnetic core micro inductor. As shown in Figure 20 .

[0104] (11) Soak in 70℃ NMP solvent for 3.5 hours to remove the photoresist first sacrificial layer 22 of the magnetic core micro inductor device, and then use 3% by volume dilute nitric acid to etch and remove the seed layer inside the magnetic core micro inductor structure and the wafer; use 2% by volume hydrofluoric acid solution to etch and remove the adhesion layer.

[0105] (12) Obtain the final magnetic core micro inductor structure, as shown in Figure 21 .

[0106] Referring to Figure 21 and Figure 22 , in particular, the structure of the magnetic core micro inductor includes: a substrate 21; a first layer of electroplated metal layer 23 arranged on the upper surface of the substrate 21; a magnetic core structure 28, the upper and lower sides of the magnetic core structure are respectively provided with ceramic structures 25; the magnetic core structure 28 and the ceramic structure 25 are arranged in the central region of the upper surface of the first layer of electroplated metal layer 23; a plurality of electroplated metal layers are sequentially arranged on both sides of the upper surface of the first layer of electroplated metal layer 23; the plurality of electroplated metal layers surround the magnetic core structure and the ceramic structure.

[0107] Optionally, the plurality of electroplated metal layers include a second layer of electroplated metal layer 26, a third layer of electroplated metal layer 27, a fourth layer of electroplated metal layer 29, and a fifth layer of electroplated metal layer 30, which are sequentially arranged. It should be noted that the present application is a manufacturing method for forming functional devices by photoetching, electroplating, and assembling process. The manufacturing method is not limited to the functional devices of the five-layer structure of the micro coaxial transmission line and the magnetic core micro inductor mentioned in the embodiment, and can be flexibly changed according to different functions. These should be understood.

[0108] In addition, it should be noted that the use of "first", "second" and the like to define parts is only for the convenience of distinguishing the corresponding parts, and the above words have no special meaning unless otherwise stated, and therefore cannot be understood as limiting the scope of protection of the present application.

[0109] In the embodiments provided by the present disclosure, it should be understood that the disclosed apparatus and method can also be implemented in other manners. The embodiments described above are merely exemplary for describing the present disclosure. After the above description of the present disclosure, it will be apparent to those skilled in the art that the apparatus embodiments can be implemented by other ways, for example, the flowcharts and block diagrams in the accompanying drawings show the possible implementation architectures, functions and operation of the apparatus, method and computer program product according to the embodiments of the present disclosure. In this regard, each block in the flowcharts and block diagrams can represent a module, a segment or a portion of code which comprises one or more executable instructions for implementing the specified logic function. It should also be noted that in some alternative implementations, the functions shown in the blocks can be performed in a different order from that shown in the flowcharts and block diagrams. For example, the two consecutive blocks can actually be performed at the same time, or in reverse order, depending on the functions involved. It should also be noted that each block in the flowcharts and / or block diagrams and combinations of blocks in the flowcharts and / or block diagrams can be implemented by a dedicated hardware-based system, or a combination of a special-purpose hardware and computer instructions.

[0110] It should be noted that in the present disclosure, the terms "comprising", "containing" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that comprises a list of elements does not only include those elements, but also includes other elements not expressly listed or inherent to such process, method, article or apparatus. Without more limitations, the element limited by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising the element.

[0111] Although the embodiments of the present disclosure are as described above, the above description is merely for the purpose of facilitating the understanding of the present disclosure, and is not intended to limit the present disclosure. Any modification and change within the spirit and scope of the present disclosure can be made by those skilled in the art without departing from the spirit and scope of the present disclosure, and the patent protection scope of the present disclosure shall be subject to the scope defined by the appended claims.

Claims

1. A method of fabricating microstructures in a litho-electroplating-assembly process, characterized by, The application relates to a microstructure manufacturing method. The microstructure is designed according to material selection and layer height processing rules of the process; The main body part of the microstructure is formed through a photoetching-plating process based on the designed microstructure; in the process of forming the main body part of the microstructure, a reserved position of an assembled structure is also formed, and the assembled structure is implanted into the reserved position.

2. The method of claim 1, wherein the method is performed by a lithography- electroplating-assembly process. The assembled structure is a heterogeneous structure; the assembled structure comprises at least one of metal, ceramic and polymer.

3. The method of claim 1, wherein the method is characterized by, The main body part is a plating metal.

4. The method of claim 1, wherein the method is characterized by, The implantation of the assembled structure into the reserved position comprises: An automatic identification glue dispenser is used to automatically identify the reserved position of the assembled structure, and a glue nozzle of the glue dispenser is moved to the center of the reserved position of the assembled structure to perform glue dispensing; An automatic identification die bonder is used to align the center position of the assembled structure, and the assembled structure is sucked by an automatic suction nozzle, then the automatic suction nozzle is moved and aligned with the center of the reserved position of the assembled structure on a wafer, the reserved position or the suction nozzle is controlled to move in a direction perpendicular to a horizontal direction by the die bonder, so that the assembled structure is placed in the reserved position of the assembled structure after glue dispensing and contacts die adhesive, the suction nozzle stops sucking the die, and the assembled structure is implanted into the reserved position of the assembled structure.

5. The method of claim 1, wherein the method further comprises: The main body part of the microstructure is formed through a photoetching-plating process based on the designed microstructure, and comprises: Step 011: a wafer is taken as a substrate, an adhesion layer is sputtered and grown on a surface of the wafer based on a design structure, and a conductive seed layer is formed on the adhesion layer; Step 012: photoresist is coated on a surface of the conductive seed layer, and photoetching is performed based on a design structure to obtain a photoetched pattern of the microstructure; Step 013: a metal material is plated on the wafer on which the photoetched pattern is formed; Step 014: after the thickness of the metal material and the photoresist on the surface of the wafer is controlled to a target thickness through a planarization process, a first layer structure of the microstructure is obtained; Step 015: steps 012-014 are repeatedly repeated on the first layer structure until the main body part of the microstructure is obtained.

6. The method of claim 5, wherein the method further comprises: After the main body part of the microstructure is formed through the photoetching-plating process based on the designed microstructure, the sacrificial layer of the main body part is removed to obtain a final microstructure.

7. The method of manufacturing a microstructure according to claim 6, wherein The sacrificial layer of the main body part is removed to obtain the final microstructure, and comprises: The microstructure is soaked in a photoresist removing solvent to remove the photoresist sacrificial layer; After the sacrificial layer is removed, a seed layer of the microstructure and the wafer is removed through dilute nitric acid corrosion; The adhesion layer of the microstructure is removed through hydrogen fluoride solution corrosion.

8. The method of claim 6, wherein the method further comprises: After the sacrificial layer of the main body part is removed to obtain the final microstructure, the following steps are further included: The substrate is removed; or The substrate is wafer diced to form independent devices.

9. The method of claim 1, wherein the method is performed by a litho- electroplating- assembly process. The microstructure comprises a multilayer structure, and the height of each layer structure is 100 mu m or 50 mu m.

10. The method of claim 1, wherein the method is performed by a litho- electroplating- assembly process. The forming of the reserved positions of the assembled structures and implanting the assembled structures into the reserved positions include: in the process of forming the main part of the microstructure, the reserved positions of the assembled structures of different levels are formed, and all the assembled structures are implanted into the corresponding reserved positions; the thickness of the assembled structure is 90-100 μm; the cross-sectional area of the assembled structure is 0.04mm 2 -400mm 2 .

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