Coil structure and MEMS device

Abstract

The utility model provides a coil structure and an MEMS device. The coil structure comprises a substrate and a coil arranged on the substrate. The surface of one side of the substrate is provided with a groove which is recessed inwards, the track of the groove spirally extends from the center of the surface of the substrate to the periphery of the substrate, the surface of the side, provided with the groove, of the substrate is provided with a thin film layer, the coil is arranged in the groove, and the thin film layer is arranged on the surface of the side, provided with the coil, of the substrate. The coil or the side wall of the groove is provided with a stress release hole. According to the coil structure and the MEMS device provided by the invention, the extrusion force of the coil on the substrate in stress deformation can be effectively reduced, the deformation or cracking problem of the substrate caused by stress is reduced, the product quality and the product yield are improved, and the rejection rate and the production cost are reduced.

Description

Technical Field

[0001] The present application relates to the field of semiconductor equipment technology, and in particular to a coil structure and a MEMS device. Background Art

[0002] In recent years, micro-electro-mechanical systems (MEMS), or micro-electro-mechanical systems, have been widely used in intelligent systems, consumer electronics, wearable devices, smart home systems, biotechnology, and microfluidics. Common products include MEMS accelerometers, MEMS microphones, micromotors, micropumps, microvibrators, MEMS pressure sensors, MEMS gyroscopes, MEMS humidity sensors, and their integrated products.

[0003] Compared to microelectronics, MEMS adds mechanical structures at the micro-nano scale, and achieves sensing and execution functions by driving these mechanical structures. Currently, the driving principles of MEMS chips mainly include electrostatic, piezoelectric, electromagnetic, and thermoelectric methods. Among them, electromagnetic drive is more widely used when large driving force is required. A common method of MEMS electromagnetic drive is to use semiconductor technology to manufacture integrated copper coils on the chip structure, combined with an external magnetic field, to achieve drive using the Lorentz force.

[0004] The preparation of the coil usually involves forming a groove structure on the substrate wafer through a dry or wet etching process, then using a wet electroplating process to fill the groove structure with copper, and finally through a flattening process such as CMP (chemical mechanical polishing) to form the final copper coil structure.

[0005] During the development of this application, the inventors discovered the following problem with the prior art: Due to the significant difference in thermal expansion coefficients between the copper material and the substrate material, conventional manufacturing processes often result in significant stress during subsequent manufacturing processes due to thermal mismatches caused by process temperatures. This can lead to wafer warping or structural cracking, resulting in product rejection. The prior art solution to this problem involves adding an annealing step to the subsequent process temperature after copper coil electroplating to preemptively release the copper coil stress. However, this still carries a significant risk of wafer deformation or structural cracking, resulting in high scrap rates.

[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 and 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 and a MEMS device to improve the problem of deformation and cracking of substrate materials caused by high stress in the prior art.

[0008] To achieve the above objectives, 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, the coil structure comprising a substrate and a coil provided on the substrate;

[0010] A groove concave inward is provided on one side surface of the substrate, and the trajectory of the groove extends spirally 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 where the groove is provided, and the coil is provided in the groove. A stress relief hole is provided on the coil or on the side wall of the groove.

[0011] In one embodiment, 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.

[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 embodiment, 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 embodiment, 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] 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 relief hole on the coil or in a groove on the surface of the substrate. The stress relief hole can release the stress of the coil, thereby reducing the impact 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. 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, also has the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the cross-sectional structure of the coil structure made by traditional technology.

[0018] Figure 2 for Figure 1 Schematic diagram of the locations where cracking is prone to occur in the coil structure.

[0019] Figure 3 This is a schematic cross-sectional view of a coil structure according to an embodiment of the present application (stress relief holes are provided in the coil).

[0020] Figure 4 This is a schematic cross-sectional view of a coil structure according to another embodiment of the present application (stress relief holes are provided on the side walls of the groove).

[0021] 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.

[0022] 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.

[0023] 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).

[0024] Figure 8 for Figure 3 Schematic diagram of the structure after the copper layer is electroplated in the groove of the coil structure.

[0025] Figure 9 for Figure 4 Schematic diagram of the structure after the copper layer is electroplated in the groove of the coil structure.

[0026] The meanings of the reference numerals in the accompanying drawings are as follows:

[0027] 1. Substrate; 12. Groove; 11. Crack; 2. Coil; 3. Thin film layer; 4. Stress relief hole. DETAILED DESCRIPTION

[0028] The technical solution of this application is further elaborated in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are intended only to describe specific embodiments and are not intended to limit the implementation of this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] In the description of this application, it should be understood that the terms "center," "up," "down," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting this application. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0031] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0032] 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 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.

[0033] See also Figure 3 and Figure 4 The coil structure of the embodiment of the present application is used in a MEMS device. The coil structure includes a substrate 1 and a coil 2 disposed on substrate 1. The substrate wafer is generally made of a semiconductor material such as silicon, glass, or quartz. The coil 2 can be made of a conductive metal. In this embodiment, the coil 2 is made of copper.

[0034] like Figure 5 and Figure 6 As shown, one side surface (upper surface) of the substrate 1 is provided with an inwardly recessed groove 12, as shown in FIG. 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, and 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.

[0035] 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 7The coil 12 may be formed as a circular spiral or a snail coil, as long as it forms a continuous, extended structure from the inside out. The number of turns in the coil is not limited. The grooves 12 can be patterned using photolithography, and the concave structure formed using dry or wet etching. To meet the requirements of high coil density and depth, grooves 12 may be wider, deeper, and have a greater number of turns.

[0036] 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. The thin film layer 3 is provided on the surface of the substrate 1 on the side where the groove 12 is provided. The thin film layer 3 can be formed by sputtering, spin coating, atomic layer deposition, or chemical vapor deposition. The thin 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 thin film layer 3 of this embodiment has a low Young's modulus, which can provide electrical isolation while also providing a certain buffering effect on the stress expansion and deformation of the coil 2.

[0037] like Figure 3 As shown, when the coil 2 is provided with a stress relief hole 4, the stress relief hole 4 is located inside the coil 2. The stress relief hole 4 is a sealed cavity structure formed inside the coil 2, and the coil 2 completely fills the groove 12. When the coil 2 expands and deforms under stress, it can deform and grow toward the stress relief hole 4, thereby reducing the squeezing force on the substrate 1.

[0038] like Figure 4 As shown, when a stress relief hole 4 is provided on the sidewall of the groove 12, the stress relief hole 4 is formed by the sidewall of the groove 12 being recessed into the substrate 1, and the stress relief hole 4 is located in the middle of the sidewall of the groove 12. The rest of the area in the groove 12, except for the stress relief hole 4, is filled with the coil 2. The bottom of the stress relief hole 4 is an arc-shaped surface, and the connection between the stress relief hole 4 and the sidewall of the groove 12 is a smooth transition. The arc-shaped bottom surface of the stress relief hole 4 and the smooth transition between the stress relief hole 4 and the sidewall of the groove 12 can reduce stress concentration caused by sharp corners. At the same time, it can make it easier for the coil 2 to enter the stress relief hole 4 when it expands and deforms due to stress. At this time, the coil 2 fills the entire groove 12, except for the stress relief hole 4. The space in the stress relief hole 4 is used to provide accommodation space for the coil 2 after deformation. The stress relief hole 4 can provide sufficient space for the coil 2 to grow and expand, preventing the coil 2 from squeezing the sidewall of the groove 12, thereby reducing the risk of deformation or cracking of the substrate 1.

[0039] This embodiment also provides a method for preparing a coil structure, which is used to prepare the coil structure of the above embodiment.

[0040] The method for preparing the coil structure with the stress relief hole 4 provided on the coil 2 is as follows:

[0041] S1. Provide a substrate 1 having an inwardly recessed groove 12 on one side surface. The groove 12 extends spirally from the center of the substrate 1 surface toward the periphery of the side surface of the substrate 1.

[0042] 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.

[0043] 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 by an electroplating process to form a coil 2. At the same time, a closed cavity is formed inside the coil 2, which is the stress relief hole 4 (as shown). Figure 8 shown).

[0044] 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.

[0045] S22. Deposit a layer of 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 process, 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 sidewalls of the groove 12, so that the copper fills the entire area of ​​the groove 12 and forms a closed cavity inside the coil 2. 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 sidewalls of the groove 12, that is, the growth rate at the corner of the groove 12 close to the upper surface of the substrate 1 is the largest, and the growth rate at the bottom of the groove 12 and the sidewalls of the groove 12 is relatively small. By controlling the growth rate, a closed cavity is formed inside the coil 2.

[0046] S3, remove the copper layer and thin film layer 3 protruding from the upper surface of the substrate 1 through a flattening process to form a coil structure (such as Figure 3 shown).

[0047] 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, which is convenient for subsequent processes.

[0048] The preparation method of the coil structure with the stress relief 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. The difference is:

[0049] S1. Provide a substrate 1 having an inwardly recessed groove 12 on one side of the surface. The groove 12 extends spirally from the center of the surface of the substrate 1 toward the periphery of the substrate 1 .

[0050] 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. By adjusting the etching process parameters, an inwardly recessed stress relief hole 4 is formed on the sidewall of the groove 12.

[0051] 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). Figure 9 shown).

[0052] 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.

[0053] 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.

[0054] The present application also provides a MEMS device including the coil structure of 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, or an integrated product thereof.

[0055] The coil structure provided in the embodiments of the present application is provided with stress relief holes. The provision of the stress relief holes provides space for the coil stress to expand and deform, thereby reducing the coil's compression on the substrate and preventing the substrate from deforming or cracking. The preparation method of the coil structure in the embodiments of the present application is simple and ingeniously designed. By regulating the growth rate of the copper electroplating in the substrate groove, the stress relief holes can be generated within the coil, or by regulating the growth direction of the copper electroplating, the copper growth can be avoided in the location of the stress relief holes. The ingenious generation and placement of the stress relief holes greatly reduces the risk of substrate deformation or cracking.

[0056] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0057] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection 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) provided on the substrate (1); A groove (12) recessed inward is provided on one side surface of the substrate (1), and the trajectory of the groove (12) spirally extends 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, and the coil (2) is provided in the groove (12). 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, 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.

3. The coil structure according to claim 1, wherein: 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, wherein: 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 areas in the groove (12) except the release hole are filled with the coil (2).

5. The coil structure according to claim 4, wherein: 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.

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