Coil structure, MEMS device and preparation method of coil structure
The coil structure with stress release holes and thin film layers addresses thermal stress issues, enhancing MEMS coil density and depth by reducing substrate deformation and cracking, thus improving production efficiency.
Patent Information
- Application Number
- CN202411576377.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-06
- Publication Date
- 2024-12-24
AI Technical Summary
The traditional manufacturing process of MEMS electromagnetic coils faces issues with thermal stress between copper and substrate materials, leading to warping and cracking of the wafer, limiting the density and depth of copper coils and hindering the development of MEMS chips.
A coil structure with stress release holes on the coil or groove side walls, combined with a thin film layer to buffer stress, is introduced, allowing for controlled copper growth and reducing substrate deformation.
The stress release holes provide space for copper expansion, reducing substrate deformation and cracking, improving yield and reducing production costs while enabling higher coil density and depth.
Smart Images
Figure CN119181577A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor equipment technology, and in particular to a coil structure, a MEMS device, and a method for preparing the coil structure. Background Art
[0002] In recent years, Micro-Electro-Mechanical Systems (MEMS) have been widely used in intelligent systems, consumer electronics, wearable devices, smart home systems, biotechnology, microfluidics and other fields. Common products include MEMS accelerometers, MEMS microphones, micromotors, micropumps, microvibrators, MEMS pressure sensors, MEMS gyroscopes, MEMS humidity sensors, and their integrated products.
[0003] Compared with microelectronics, MEMS adds mechanical structures at the micro-nano scale, and achieves sensing and execution functions by driving these mechanical structures. At present, the driving principles of MEMS chips mainly include electrostatic, piezoelectric, electromagnetic, and thermoelectric methods. Among them, electromagnetic drive is widely used under the requirement of large driving force. A common method of MEMS electromagnetic drive is to manufacture an integrated copper coil on the chip structure through semiconductor technology, combined with an external magnetic field, and use the Lorentz force to achieve drive.
[0004] The preparation of the coil usually involves forming a groove structure on a substrate wafer through a dry or wet etching process, then using a wet electroplating process to fill the groove structure with copper, and finally using a planarization process such as CMP (chemical mechanical polishing) to form the final copper coil structure.
[0005] In the process of realizing this application, the inventor discovered that the prior art has the following problems: Due to the large difference in thermal expansion coefficients between copper materials and substrate materials, the traditional manufacturing process often generates large stresses due to the thermal mismatch between the two materials caused by the process temperature in the subsequent process, which leads to the warping of the wafer or structural cracking, making the product scrapped. The solution to this problem in the prior art is to add an annealing step based on the subsequent process temperature after the copper coil is electroplated to release the stress of the copper coil in advance, but the wafer still has a large risk of deformation or structural cracking, resulting in a high scrap rate.
[0006] With the increasing demand for miniaturization and low power consumption of MEMS chips, the density and depth of copper coils are constantly being required to increase, which makes the stress problem of copper coils more serious. That is, the stress problem of copper coils limits the increase in their density and depth, hindering the development of MEMS chips. Summary of the invention
[0007] Based on this, the present application provides a coil structure, a MEMS device and a method for preparing the coil structure, so as to improve the problem of deformation and cracking of substrate materials caused by high stress existing in the prior art.
[0008] To achieve the above purpose, the technical solution of the embodiment of the present application is implemented as follows:
[0009] In a first aspect, an embodiment of the present application provides a coil structure for a MEMS device, wherein the coil structure includes a substrate and a coil disposed on the substrate;
[0010] A groove recessed inwardly is provided on one surface of the substrate, and the trajectory of the groove spirally extends from the center of the substrate surface to the periphery of the substrate. A thin film layer is provided on the surface of the substrate on the side provided with the groove, the coil is provided in the groove, and a stress release hole is provided on the coil or on the side wall of the groove.
[0011] In one embodiment, the film layer includes one or more of a polyimide film layer, a photoresist film layer, an aluminum oxide film layer, a zirconium oxide film layer, a silicon oxide film layer or a silicon nitride film layer.
[0012] In one embodiment, when the stress relief hole is provided on the coil, the stress relief hole is located inside the coil, and the coil fills the groove.
[0013] In one of the embodiments, when the stress release hole is provided on the side wall of the groove, the stress release hole is formed by the side wall of the groove being recessed into the substrate, and the stress release hole is located in the middle of the side wall of the groove, and the other areas in the groove except the release hole are filled with the coil.
[0014] In one of the embodiments, the bottom of the stress release hole is an arc-shaped surface, and the connection between the stress release hole and the side wall of the groove is smoothly transitioned.
[0015] In a second aspect, the present application provides a MEMS device, comprising the coil structure as described above.
[0016] In a third aspect, an embodiment of the present application provides a method for preparing a coil structure, wherein the coil structure is used for a MEMS device, comprising the following steps:
[0017] Providing a substrate having a groove recessed inwardly formed on one side of the surface, wherein the track of the groove extends from the center of the substrate surface to the periphery of the substrate in a spiral shape;
[0018] If a stress relief hole is provided on the side wall of the groove, the following steps are performed:
[0019] Depositing a thin film layer on the surface of the substrate on one side of the groove, depositing an electroplating seed layer on the thin film layer, and plating conductive metal in other areas of the groove except the position of the stress release hole by electroplating to form a coil;
[0020] If the coil is provided with a stress relief hole, perform the following steps:
[0021] A thin film layer is deposited on the surface of the substrate on one side of which the groove is provided, and an electroplating seed layer is deposited on the thin film layer. A conductive metal is plated on the entire area within the groove through an electroplating process to form a coil. At the same time, a closed cavity is formed inside the coil, and the cavity is the stress release hole.
[0022] In one embodiment, the step of "providing a substrate having a groove recessed inwardly on one surface" specifically includes:
[0023] A silicon, glass or quartz semiconductor substrate material is provided, an extension track of the groove is defined by photolithography, and the groove is formed by an etching process; when a stress release hole is opened on the side wall of the groove, the stress release hole that is recessed inward is formed on the side wall of the groove by adjusting the etching process parameters.
[0024] In one embodiment, when a stress release hole is provided on the side wall of the groove, the steps specifically include:
[0025] Depositing a thin film layer on the surface of the substrate on the side where the groove is provided by sputtering, spin coating, atomic layer deposition or chemical vapor deposition, wherein the thin film layer includes one or more of a polyimide thin film layer, a photoresist thin film layer, an aluminum oxide thin film layer, a zirconium oxide thin film layer, a silicon oxide thin film layer or a silicon nitride thin film layer;
[0026] Depositing an electroplated copper seed layer on the thin film layer in the groove, and filling the groove by an electroplating process to form the coil in the groove; during the electroplating, regulating the growth direction of the copper, promoting the growth in a direction perpendicular to the bottom plane of the groove, and inhibiting the growth in a direction parallel to the bottom plane of the groove, so that the copper fills the area of the groove except the stress release hole;
[0027] The copper layer and the thin film layer protruding from the upper surface of the substrate are removed by a planarization process.
[0028] In one embodiment, when the coil is provided with a stress relief hole, the steps are specifically included:
[0029] Depositing a thin film layer on the surface of the substrate on the side where the groove is provided by sputtering, spin coating, atomic layer deposition or chemical vapor deposition, wherein the thin film layer includes one or more of a polyimide thin film layer, a photoresist thin film layer, an aluminum oxide thin film layer, a zirconium oxide thin film layer, a silicon oxide thin film layer or a silicon nitride thin film layer;
[0030] Depositing an electroplated copper seed layer on the thin film layer in the groove, and filling the groove by an electroplating process to form the coil in the groove; during the electroplating, regulating the growth rate of copper so that the growth rate at the top of the groove is greater than the growth rate at the bottom of the groove and the side wall of the groove, so that copper fills the entire area of the groove and forms a closed cavity inside the coil, and the closed cavity is the stress release hole;
[0031] The copper layer and the thin film layer protruding from the upper surface of the substrate are removed by a planarization process.
[0032] The present application has at least the following beneficial effects: the coil structure of the embodiment of the present application is provided with a stress release hole on the coil or in a groove on the surface of the substrate, and the stress release hole can release the stress of the coil, thereby reducing the influence of the stress on the substrate, avoiding deformation or cracking of the substrate, thereby improving the yield rate of the product and reducing production costs. A thin film layer is provided in the groove of the substrate, and the thin film layer has a certain buffering effect on the stress expansion and deformation of the coil, which can further reduce the risk of deformation or cracking of the substrate. The MEMS device of the embodiment of the present application includes the above-mentioned coil structure, and therefore, it also has the above-mentioned beneficial effects. The preparation method of the coil structure of the embodiment of the present application has simple steps, and the above-mentioned coil structure can be prepared by this method, and therefore, it also has the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 Schematic diagram of the cross-sectional structure of the coil structure made by traditional technology.
[0034] Figure 2 for Figure 1 Schematic diagram of the locations where cracks are prone to occur in the coil structure.
[0035] Figure 3 This is a schematic cross-sectional structural diagram of a coil structure according to an embodiment of the present application (a stress release hole is provided in the coil).
[0036] Figure 4 This is a schematic cross-sectional structural diagram of a coil structure according to another embodiment of the present application (stress release holes are provided on the side walls of the groove).
[0037] Figure 5 for Figure 3 Schematic diagram of the structure after a thin film layer is deposited on the substrate surface of the coil structure.
[0038] Figure 6 for Figure 4 Schematic diagram of the structure after a thin film layer is deposited on the substrate surface of the coil structure.
[0039] Figure 7 Schematic diagram of the top view of the coil structure of an embodiment of the present application (on one surface side of the substrate).
[0040] Figure 8 for Figure 3 Schematic diagram of the structure after the copper layer is electroplated in the groove of the coil structure.
[0041] Fig. 9 for Figure 4 Schematic diagram of the structure after the copper layer is electroplated in the groove of the coil structure.
[0042] The meanings of the symbols in the accompanying drawings are as follows:
[0043] 1. Substrate; 12. Groove; 11. Crack; 2. Coil; 3. Thin film layer; 4. Stress relief hole. DETAILED DESCRIPTION
[0044] The technical solution of the present application is further elaborated in detail below in conjunction with the accompanying drawings and specific embodiments of the specification.
[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit the implementation of this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.
[0046] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating positions or positional relationships, are based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present application. In the description of the present application, unless otherwise specified, "multiple" means two or more.
[0047] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0048] The coil structure made by traditional technology is as follows Figure 1 As shown, the stress of the coil 2 often causes the substrate 1 to crack. The location of the crack 11 is as shown in FIG. Figure 2 As shown, in order to improve the deformation or cracking of the substrate 1, the solution of the present application is developed to improve the overall quality of the coil structure.
[0049] See also Figure 3 and Figure 4 The coil structure of the embodiment of the present application is used for a MEMS device, and the coil structure includes a substrate 1 and a coil 2 disposed on the substrate 1. The material of the substrate wafer is generally a semiconductor material such as silicon, glass, quartz, etc. The material of the coil 2 can be a conductive metal, and the material of the coil 2 in this embodiment is copper.
[0050] like Figure 5 and Figure 6 As shown, a groove 12 is formed on one side surface (upper surface) of the substrate 1. Figure 7 As shown, the trajectory of the groove 12 extends spirally from the center of the surface of the substrate 1 to the periphery of the substrate 1, a thin film layer 3 is provided on the surface of the substrate 1 on the side where the groove 12 is provided, a coil 2 is provided in the groove 12, and a stress release hole 4 is provided on the coil 2 or on the side wall of the groove 12.
[0051] In this embodiment, the cross section of the groove 12 is square or rectangular, and the groove 12 gradually extends from the middle of the upper surface of the substrate 1 to the periphery in a spiral shape. The specific shape of the spiral here is not limited, for example, it can be a square spiral line (such as Figure 7 As shown in the figure, it can also be other circular spirals, snail lines, etc., as long as it can form an integral extended structure from the inside to the outside, and the number of turns of the coil spiral is not limited. The groove 12 can form a track pattern by photolithography, and form an inner concave structure by dry or wet etching. In order to meet the requirements of high density and deepness of the coil 2, a wider, deeper and more turns of the groove 12 can be set accordingly.
[0052] The film layer 3 includes one or more of a polyimide film layer, a photoresist film layer, an aluminum oxide film layer, a zirconium oxide film layer, a silicon oxide film layer or a silicon nitride film layer. The film layer 3 is provided on the surface of the substrate 1 on the side where the groove 12 is provided, and the film layer 3 can be formed by sputtering, spin coating, atomic layer deposition or chemical vapor deposition. The film layer 3 covers the entire surface of the substrate 1 on the side where the groove 12 is provided, including the upper surface of the substrate 1 and the bottom and sidewalls of the groove 12. The material of the film layer 3 of this embodiment has a low Young's modulus, which can provide electrical isolation while also playing a certain buffering role in the stress expansion deformation of the coil 2.
[0053] like Figure 3 As shown, when the coil 2 is provided with a stress release hole 4, the stress release hole 4 is located inside the coil 2, and the stress release hole 4 is a sealed cavity structure formed inside the coil 2, and the coil 2 fills the entire groove 12. When the coil 2 is deformed by stress expansion, it can deform and grow toward the stress release hole 4, thereby reducing the squeezing force on the substrate 1.
[0054] like Figure 4 As shown, when a stress release hole 4 is provided on the side wall of the groove 12, the stress release hole 4 is formed by the side wall of the groove 12 being recessed into the substrate 1, and the stress release hole 4 is located in the middle of the side wall of the groove 12, and the other areas in the groove 12 except the stress release hole 4 are filled with the coil 2. The bottom of the stress release hole 4 is an arc surface, and the connection between the stress release hole 4 and the side wall of the groove 12 is a smooth transition. The arc-shaped bottom surface of the stress release hole 4 and the smooth transition design of the connection between the stress release hole 4 and the side wall of the groove 12 can reduce the stress concentration caused by the sharp corners, and at the same time, it can make it easier for the coil 2 to enter the stress release hole 4 when the stress expands and deforms. At this time, the coil 2 fills the entire groove 12, except for the stress release hole 4. The space of the stress release hole 4 is used to provide a accommodating space for the coil 2 after deformation. The stress release hole 4 can provide sufficient growth and expansion space for the coil 2 to avoid the coil 2 from squeezing the side wall of the groove 12, thereby reducing the risk of deformation or cracking of the substrate 1.
[0055] This embodiment also provides a method for preparing a coil structure, which is used to prepare the coil structure of the above embodiment.
[0056] The preparation method of the coil structure with the stress release hole 4 provided on the coil 2 is as follows:
[0057] S1. Provide a substrate 1 having a groove 12 recessed inwardly formed on one side surface. The track of the groove 12 extends from the center of the surface of the substrate 1 to the periphery of the side surface of the substrate 1 in a spiral shape.
[0058] Specifically, a semiconductor substrate 1 material of silicon, glass or quartz is provided, an extension track of the groove 12 is defined by photolithography, and the groove 12 is formed by an etching process.
[0059] S2, depositing a thin film layer 3 (such as Figure 5 As shown), a plating seed layer is deposited on the film layer 3, and a conductive metal is plated in the entire area of the groove 12 through an electroplating process to form a coil 2. At the same time, a closed cavity is formed inside the coil 2, and the cavity is the stress release hole 4 (as shown Figure 8 shown).
[0060] S21. Deposit a thin film layer 3 on the surface of the substrate 1 on the side where the groove 12 is provided by sputtering, spin coating, atomic layer deposition or chemical vapor deposition. The thin film layer 3 includes one or more of a polyimide thin film layer, a photoresist thin film layer, an aluminum oxide thin film layer, a zirconium oxide thin film layer, a silicon oxide thin film layer or a silicon nitride thin film layer.
[0061] S22, depositing a layer of electroplated copper seed layer on the thin film layer 3 in the groove 12, and filling the groove 12 by electroplating process to form a coil 2 in the groove 12. During electroplating, the growth rate of copper is regulated so that the growth rate at the top of the groove 12 is greater than the growth rate at the bottom of the groove 12 and the side wall of the groove 12, so that copper fills the entire area of the groove 12 and forms a closed cavity inside the coil 2, and the closed cavity is the stress release hole 4. The growth rate at the top of the groove 12 is greater than the growth rate at the bottom of the groove 12 and the side wall of the groove 12, that is, the growth rate of the corner of the groove 12 close to the upper surface of the substrate 1 is the largest, and the growth rate of the bottom of the groove 12 and the side wall of the groove 12 is relatively small, and the closed cavity is formed inside the coil 2 by controlling the growth rate.
[0062] S3, removing the copper layer and the thin film layer 3 protruding from the upper surface of the substrate 1 through a planarization process to form a coil structure (such as Figure 3 shown).
[0063] The redundant copper layer and the thin film layer 3 on the upper surface of the substrate 1 are removed by grinding through a planarization process such as CMP, so that the upper surface of the substrate 1 is exposed and planarized, so as to facilitate subsequent processes.
[0064] The preparation method of the coil structure with the stress release hole 4 opened on the side wall of the groove 12 is similar to the above preparation method, and the same parts are not repeated here, except that:
[0065] S1. Provide a substrate 1 having a groove 12 recessed inwardly formed on one side surface. The track of the groove 12 extends from the center of the surface of the substrate 1 to the periphery of the substrate 1 in a spiral shape.
[0066] Specifically, a semiconductor substrate 1 of silicon, glass or quartz is provided, an extension track of the groove 12 is defined by photolithography, and an etching process is used to form the groove 12. An inwardly recessed stress release hole 4 is formed on the sidewall of the groove 12 by adjusting etching process parameters.
[0067] S2, depositing a thin film layer 3 (such as Figure 6 As shown), a plating seed layer is deposited on the film layer 3, and a conductive metal is plated in other areas of the groove 12 except the stress release hole 4 by an electroplating process to form a coil 2 (as shown in FIG. Fig. 9 shown).
[0068] S21. Deposit a thin film layer 3 on the surface of the substrate 1 on the side where the groove 12 is provided by sputtering, spin coating, atomic layer deposition or chemical vapor deposition. The thin film layer 3 includes one or more of a polyimide thin film layer, a photoresist thin film layer, an aluminum oxide thin film layer, a zirconium oxide thin film layer, a silicon oxide thin film layer or a silicon nitride thin film layer.
[0069] S22. Deposit an electroplated copper seed layer on the thin film layer 3 in the groove 12, and fill the groove 12 through an electroplating process to form a coil 2 in the groove 12; during the electroplating, regulate the growth direction of the copper to promote growth in a direction perpendicular to the bottom plane of the groove 12 and inhibit growth in a direction parallel to the bottom plane of the groove 12, so that the copper fills the area of the groove 12 except the stress release hole 4.
[0070] The present application also provides a MEMS device, including the coil structure in the above embodiment. The MEMS device may be, for example, a MEMS accelerometer, a MEMS microphone, a micromotor, a micropump, a microvibrator, a MEMS pressure sensor, a MEMS gyroscope, a MEMS humidity sensor, and their integrated products.
[0071] The coil structure provided in the embodiment of the present application is provided with stress release holes, and the setting of the stress release holes provides growth space for the stress expansion and deformation of the coil, thereby reducing the squeezing of the coil on the substrate and avoiding deformation or cracking of the substrate. The preparation method of the coil structure provided in the embodiment of the present application has simple steps and ingenious design. The stress release holes can be generated inside the coil by regulating the growth rate of copper electroplating at the groove of the substrate, or the growth direction of copper electroplating can be regulated to make the growth of copper avoid the position of the stress release holes. The ingenious generation and setting of the stress release holes greatly reduces the risk of deformation or cracking of the substrate.
[0072] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.
[0073] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.
Claims
1. A coil structure for a MEMS device, characterized in that: The coil structure comprises a substrate (1) and a coil (2) arranged on the substrate (1); A groove (12) recessed inwardly is provided on one side surface of the substrate (1), the track of the groove (12) extending in a spiral shape from the center of the surface of the substrate (1) to the periphery of the substrate (1), a thin film layer (3) is provided on the surface of the substrate (1) on the side where the groove (12) is provided, the coil (2) is provided in the groove (12), and a stress release hole (4) is provided on the coil (2) or on the side wall of the groove (12).
2. The coil structure according to claim 1, characterized in that: The thin film layer (3) comprises one or more of a polyimide thin film layer, a photoresist thin film layer, an aluminum oxide thin film layer, a zirconium oxide thin film layer, a silicon oxide thin film layer or a silicon nitride thin film layer.
3. The coil structure according to claim 1, characterized in that: When the stress release hole (4) is provided on the coil (2), the stress release hole (4) is located inside the coil (2), and the coil (2) fills the groove (12).
4. The coil structure according to claim 1, characterized in that: When the stress release hole (4) is provided on the side wall of the groove (12), the stress release hole (4) is formed by the side wall of the groove (12) being recessed into the substrate (1), and the stress release hole (4) is located in the middle of the side wall of the groove (12), and the other area in the groove (12) except the release hole is filled with the coil (2).
5. The coil structure according to claim 4, characterized in that: The bottom of the stress release hole (4) is an arc-shaped surface, and the connection between the stress release hole (4) and the side wall of the groove (12) is smoothly transitioned.
6. A MEMS device, characterized in that: Comprising the coil structure according to any one of claims 1 to 5.
7. A method for preparing a coil structure, wherein the coil structure is used for a MEMS device, characterized in that: The following steps are involved: A substrate (1) is provided with an inwardly recessed groove (12) on one side surface, wherein the track of the groove (12) extends in a spiral shape from the center of the surface of the substrate (1) to the periphery of the substrate (1); If a stress release hole (4) is provided on the side wall of the groove (12), the following steps are performed: Depositing a thin film layer (3) on the surface of the substrate (1) on the side where the groove (12) is provided, depositing an electroplating seed layer on the thin film layer (3), and plating conductive metal in other areas of the groove (12) except for the position of the stress release hole (4) through an electroplating process to form a coil (2); If the coil (2) is provided with a stress relief hole (4), the following steps are performed: A thin film layer (3) is deposited on the surface of the substrate (1) on the side where the groove (12) is provided, and an electroplating seed layer is deposited on the thin film layer (3). A conductive metal is plated on the entire area within the groove (12) through an electroplating process to form a coil (2). At the same time, a closed cavity is formed inside the coil (2), and the cavity is the stress release hole (4).
8. The method for preparing a coil structure according to claim 7, characterized in that: The step of "providing a substrate (1) having a groove (12) recessed inwardly formed on one side surface" specifically comprises: A semiconductor substrate (1) material of silicon, glass or quartz is provided, an extension track of the groove (12) is defined by photolithography, and the groove (12) is formed by an etching process; when a stress release hole (4) is provided on the side wall of the groove (12), the stress release hole (4) which is recessed inward is formed on the side wall of the groove (12) by adjusting etching process parameters.
9. The method for preparing a coil structure according to claim 8, characterized in that: When a stress release hole (4) is provided on the side wall of the groove (12), the method specifically comprises the following steps: Depositing a thin film layer (3) on the surface of the substrate (1) on the side where the groove (12) is provided by sputtering, spin coating, atomic layer deposition or chemical vapor deposition, wherein the thin film layer (3) comprises one or more of a polyimide thin film layer, a photoresist thin film layer, an aluminum oxide thin film layer, a zirconium oxide thin film layer, a silicon oxide thin film layer or a silicon nitride thin film layer; A layer of electroplated copper seed layer is deposited on the thin film layer (3) in the groove (12), and the groove (12) is filled by an electroplating process to form the coil (2) in the groove (12); when electroplating, the growth direction of copper is regulated to promote growth in a direction perpendicular to the bottom plane of the groove (12) and inhibit growth in a direction parallel to the bottom plane of the groove (12), so that copper fills the area of the groove (12) except the stress release hole (4); The copper layer and the thin film layer (3) protruding from the upper surface of the substrate (1) are removed through a planarization process.
10. The method for preparing a coil structure according to claim 8, characterized in that: When the coil (2) is provided with a stress release hole (4), the method specifically comprises the following steps: Depositing a thin film layer (3) on the surface of the substrate (1) on the side where the groove (12) is provided by sputtering, spin coating, atomic layer deposition or chemical vapor deposition, wherein the thin film layer (3) comprises one of a polyimide thin film layer (3), a photoresist thin film layer (3), a silicon oxide thin film layer (3) or a silicon nitride thin film layer (3); A copper electroplating seed layer is deposited on the thin film layer (3) in the groove (12), and the groove (12) is filled by an electroplating process to form the coil (2) in the groove (12); during the electroplating, the growth rate of copper is regulated so that the growth rate at the top of the groove (12) is greater than the growth rate at the bottom of the groove (12) and the side wall of the groove (12), so that copper fills the entire area of the groove (12) and forms a closed cavity inside the coil (2), and the closed cavity is the stress release hole (4); The copper layer and the thin film layer (3) protruding from the upper surface of the substrate (1) are removed through a planarization process.