A MEMS device and a method of manufacturing the same

Abstract

The application provides a MEMS device and a preparation method thereof, which comprises the following steps: providing a substrate, the substrate having opposite first and second surfaces; forming at least one blocking structure on the second surface of the substrate; forming a first mask layer on the second surface of the substrate exposed outside the blocking structure, and forming an opening exposing part of the second surface in the first mask layer, the size of the opening in the first direction being smaller than the size of the blocking structure in the first direction; performing an etching process with the first mask layer as a mask to etch and remove the blocking structure and part of the substrate below the blocking structure to form a blocking area groove, and etch and remove part of the substrate exposed by the opening to form an opening area groove, wherein the remaining substrate between the blocking area groove and the opening area groove forms a comb structure, and the depths of the blocking area groove and the opening area groove are substantially equal.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more specifically to a MEMS device and its fabrication method. Background Technology

[0002] With the rapid development of fields such as the Internet of Things, 5G communication, smart wearables, and automotive electronics, Micro-Electro-Mechanical Systems (MEMS) devices have been widely used in key applications such as radio frequency filters (e.g., thin-film bulk acoustic resonators), inertial sensors, microphones, and pressure sensors due to their advantages of small size, low power consumption, high integration, and excellent performance. In MEMS manufacturing processes, deep silicon etching is a crucial step in forming silicon-based microstructures (e.g., cavities, trenches, open regions), and the consistency of its etching depth directly determines the core indicators of the device, such as resonant frequency, sensitivity, and signal transmission efficiency.

[0003] In related technologies, deep silicon etching is typically performed on the bonded substrate to form the final functional structure during the MEMS device manufacturing process. However, due to the loading effect in deep silicon etching, when multiple opening regions with significantly different pattern sizes exist on the substrate, the actual etching rates of different regions vary considerably. Smaller opening regions are etched more slowly, while larger opening regions are etched more quickly, resulting in severely inconsistent etching depths across regions. This directly affects the structural integrity and performance consistency of the device, reducing its reliability. A common solution to this uneven etching depth problem is to modify the device pattern layout to reduce the impact of the loading effect. However, the pattern layout is designed based on the core functions of the device, and modifications inevitably sacrifice the rationality of some functional areas. This not only fails to fundamentally solve the problem of uneven etching depth but also further weakens the original performance of the device, while increasing R&D cycles and production costs, hindering industrial mass production.

[0004] Therefore, improvements are needed to at least partially address the aforementioned problems. Summary of the Invention

[0005] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. This summary section is not intended to limit the key and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0006] To address the existing problems, this application provides a method for fabricating a MEMS device, comprising: providing a substrate having opposing first and second surfaces; forming at least one barrier structure on the second surface of the substrate; forming a first mask layer on the second surface of the substrate exposed outside the barrier structure, wherein the first mask layer further forms an opening exposing a portion of the second surface, the size of the opening in a first direction being smaller than the size of the barrier structure in the first direction; and performing an etching process using the first mask layer as a mask to etch away the barrier structure and a portion of the substrate below it to form a barrier region groove, and to etch away the portion of the substrate exposed by the opening to form an opening region groove, wherein the remaining substrate between the barrier region groove and the opening region groove constitutes a comb-like structure, and the depths of the barrier region groove and the opening region groove are substantially equal.

[0007] For example, the step of using the first mask layer as a mask to perform an etching process to etch away the blocking structure and a portion of the substrate below it to form a blocking region groove, and to etch away the portion of the substrate exposed by the opening to form an opening region groove, includes: using the first mask layer as a mask to perform a first etching process to etch away the blocking structure and a portion of the substrate below it to form an initial blocking region groove, and to etch away the portion of the substrate exposed by the opening to form an initial opening region groove, wherein the depth of the initial blocking region groove is less than the depth of the initial opening region groove; and continuing to use the first mask layer as a mask to perform a second etching process to increase the depth of the initial blocking region groove and the depth of the initial opening region groove, forming the blocking region groove and the opening region groove extending from the second surface of the substrate into its interior, respectively.

[0008] Exemplarily, the at least one blocking structure includes a first blocking structure and a second blocking structure spaced apart in the first direction. The opening is located on the side of the first blocking structure away from the second blocking structure. The first blocking structure has a larger dimension in the first direction than the second blocking structure in the first direction, the opening has a smaller dimension in the first direction than the second blocking structure in the first direction, the thickness of the first blocking structure is greater than the thickness of the second blocking structure, and the first direction is perpendicular to the thickness direction of the substrate. The etching process forms a first blocking area groove, a second blocking area groove, and an opening area groove. The remaining substrate between the first blocking area groove and the second blocking area groove, and the remaining substrate between the first blocking area groove and the opening area groove, constitute the comb-like structure. The depths of the first blocking area groove, the second blocking area groove, and the opening area groove are substantially equal. For example, forming the first barrier structure and the second barrier structure includes the following steps: forming a first barrier material layer on the second surface of the substrate, and etching away a portion of the first barrier material layer to form a sub-barrier structure on the second surface of the substrate; forming a second barrier material layer covering the sub-barrier structure and covering the exposed second surface of the substrate; etching away a portion of the second barrier material layer outside the sub-barrier structure, the remaining second barrier material layer on the second surface of the substrate constituting the second barrier structure, and the remaining second barrier material layer on the sub-barrier structure and the sub-barrier structure together constituting the first barrier structure.

[0009] For example, the etching process has a higher etching rate for the substrate than for the first barrier structure and the second barrier structure.

[0010] For example, the first barrier material layer and the second barrier material layer have the same material, the first barrier material layer is made of oxide, the second barrier material layer is made of oxide, and the substrate is a silicon substrate.

[0011] For example, the substrate includes a first substrate and a second substrate, wherein a cavity is formed in the first substrate extending from the surface of the first substrate into its interior; the second substrate has opposing first and second surfaces, and the side of the first substrate in which the cavity is formed is joined to the first surface of the second substrate to form the substrate, wherein the second surface of the substrate is the second surface of the second substrate.

[0012] For example, the step of forming the cavity includes: forming a patterned second mask layer on the surface of the first substrate; etching the first substrate with the patterned second mask layer as a mask to form the cavity in the first substrate; and removing the patterned second mask layer.

[0013] For example, the distance between the cavity and the second surface of the substrate is greater than the distance between the cavity and the first surface of the substrate, and the comb structure is located above the cavity.

[0014] This application also provides a MEMS device, which is prepared by the aforementioned MEMS device preparation method.

[0015] The MEMS device and its fabrication method disclosed in this application, by setting a barrier structure on the second surface of the substrate and cooperating with a smaller opening, effectively overcomes the load effect by using the barrier structure to differentiate the etching process during the etching process. This ensures that the depth of the formed barrier area groove and the opening area groove are basically equal, effectively guaranteeing the dimensional consistency of the device structure, reducing costs, and improving the performance and reliability of the device. Attached Figure Description

[0016] The following drawings, which are incorporated herein by reference and are used to understand this application, illustrate embodiments of the invention and their descriptions to explain the principles of the invention.

[0017] In the attached image: Figures 1A to 1F A cross-sectional schematic diagram of the device structure obtained by sequentially implementing the fabrication method of the related technology for MEMS devices is shown. Figure 2 A flowchart illustrating a method for fabricating a MEMS device according to a specific embodiment of this application is shown; Figures 3A to 3K This diagram shows a cross-sectional view of the device structure obtained by sequentially implementing a method for fabricating a MEMS device according to a specific embodiment of this application. Detailed Implementation

[0018] The following description provides numerous specific details to offer a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with this application.

[0019] It should be understood that this application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of this application to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.

[0020] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.

[0021] Spatial relation terms such as “below,” “under,” “below,” “below,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0023] In related technologies, such as Figures 1A to 1FAs shown, the specific steps for forming a MEMS device are as follows: First, a first substrate 10 is provided, and a patterned first mask layer 11 is formed on the first substrate 10. Using the patterned first mask layer 11 as a mask, the first substrate 10 is etched to form a cavity 12 extending from the surface of the first substrate 10 into its interior. Next, a second substrate 13 is provided, the second substrate 13 including a first surface and a second surface. The side of the first substrate 10 where the cavity 12 is formed is bonded to the first surface of the second substrate 13. After bonding, a [missing information - likely a typo, should be inserted here] is formed on the second surface of the second substrate 13. A patterned second mask layer 14 is formed. Using the patterned second mask layer 14 as a mask, the second surface of the second substrate 13 is etched to form a first groove 15, a second groove 16, and a third groove 17 extending from the surface of the second substrate 13 into its interior. However, during the etching process, due to the load effect, the etching rate of each region is inconsistent, causing the actual etching depth to deviate from the design value. Therefore, the depths of the first groove 15, the second groove 16, and the third groove 17 formed differ significantly, resulting in a mismatch with device requirements and affecting the performance and reliability of the device.

[0024] The existing solution is mainly to modify the device pattern layout to reduce the impact of the load effect. However, the pattern layout is based on the core function design of the device. Modification will inevitably sacrifice the rationality of some functional areas. Not only will it fail to fundamentally solve the problem of uneven etching depth, but it will also further weaken the original performance of the device, while increasing the R&D cycle and production costs, which is not conducive to industrial mass production.

[0025] Therefore, in view of the aforementioned technical problems, this application proposes a method for fabricating a MEMS device, such as... Figure 2 As shown, it mainly includes the following steps: Step S1, providing a substrate having opposing first and second surfaces; Step S2: Form at least one barrier structure on the second surface of the substrate; Step S3: A first mask layer is formed on the second surface of the substrate exposed outside the barrier structure. An opening is also formed in the first mask layer to expose part of the second surface. The size of the opening in the first direction is smaller than the size of the barrier structure in the first direction. Step S4: Using the first mask layer as a mask, perform an etching process to etch away the blocking structure and part of the substrate below it to form a blocking area groove, and etch away the part of the substrate exposed by the opening to form an opening area groove. The remaining substrate between the blocking area groove and the opening area groove forms a comb structure, and the depths of the blocking area groove and the opening area groove are basically equal.

[0026] The method for fabricating MEMS devices disclosed in this application, by setting a barrier structure on the second surface of the substrate and using a smaller opening, effectively overcomes the load effect by using the barrier structure to differentiate the etching process during the etching process. This ensures that the depth of the formed barrier area groove and the opening area groove are essentially equal, effectively guaranteeing the dimensional consistency of the device structure, reducing costs, and improving the performance and reliability of the device.

[0027] To fully understand this application, detailed steps and structures will be presented in the following description to illustrate the technical solutions proposed in this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0028] Example 1 Below, for reference Figure 2 , Figures 3A to 3K The fabrication method of the MEMS device of this application is described in detail, wherein, Figure 2 A flowchart illustrating a method for fabricating a MEMS device according to a specific embodiment of this application is shown; Figures 3A to 3K This diagram shows a cross-sectional view of the device structure obtained by sequentially implementing a method for fabricating a MEMS device according to a specific embodiment of this application.

[0029] For example, the method for fabricating the semiconductor device of this application includes the following steps: First, step S1 is performed, providing a substrate having a first surface and a second surface opposite each other.

[0030] In one example, such as Figures 3A to 3DAs shown, a substrate 20 is provided, comprising a first substrate 21 and a second substrate 22. The materials of the first substrate 21 and the second substrate 22 include, but are not limited to, at least one of the following: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon germanium carbon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), sapphire, or other III / V compound semiconductors; or silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-on-insulator (S-SiGeOI), silicon-on-insulator (SiGeOI), and germanium-on-insulator (GeOI); or they may be double-side polished wafers (DSP), ceramic substrates such as alumina, quartz, or glass substrates, etc. Although several examples of materials that can form the substrate have been described herein, any material that can serve as a substrate falls within the spirit and scope of the invention. The materials of the first substrate 21 and the second substrate 22 may be the same or different, and no specific limitation is made thereto. In this embodiment, the substrate 20 is a silicon substrate, that is, the materials of the first substrate 21 and the second substrate 22 are silicon.

[0031] In one example, such as Figures 3A to 3D As shown, the substrate 20 is formed by bonding a first substrate 21 and a second substrate 22. A cavity 210 extending from the surface of the first substrate 21 into its interior is formed therein. The steps for forming the cavity 210 include: first, forming a second mask layer 211 on the surface of the first substrate 21, which can be formed using methods including but not limited to thermal oxidation or plasma-enhanced chemical vapor deposition (PECVD). The material of the second mask layer 211 includes, but is not limited to, silicon dioxide or silicon nitride. Second, patterning the second mask layer 211 to expose the area where the cavity is to be formed, for example, using an electron beam lithography system to form a patterned second mask layer 211, which defines the shape and location of the cavity 210. Next, using the patterned second mask layer 211 as a mask, etching the first substrate 21 to form the cavity 210, which extends from the surface of the first substrate 21 into its interior. Finally, removing the patterned second mask layer 211. The etching of the first substrate 21 can be performed using dry etching, which can be conventional etching processes such as reactive ion etching (RIE), ion beam etching, or plasma etching.

[0032] In one example, the second substrate 22 has opposing first and second surfaces. The side of the first substrate 21 with the cavity 210 formed is bonded to the first surface of the second substrate 22 to form a substrate 20. Specifically, a second substrate 22 is provided, and the side of the first substrate 21 with the cavity 210 formed is aligned and bonded to the first surface of the second substrate 22, such that the cavity 210 is enclosed between the first substrate 21 and the second substrate 22, thereby forming a complete substrate 20. The bonding method can employ processes including, but not limited to, direct bonding or eutectic bonding to ensure that the cavity 210 remains sealed in subsequent processes. After bonding, the formed substrate 20 has opposing first and second surfaces. The first surface of the substrate 20 is the back surface of the first substrate 21 away from the cavity 210, and the second surface of the substrate 20 is the second surface of the second substrate 22, which is used for subsequent processes such as forming barrier structures, mask layers, and performing etching. The distance between the cavity 210 and the second surface of the substrate 20 is greater than the distance between the cavity 210 and the first surface of the substrate 20. The comb structure is located above the cavity 210 and is arranged opposite to the cavity 210 along the thickness direction of the substrate.

[0033] Next, step S2 is performed to form at least one barrier structure on the second surface of the substrate.

[0034] In one example, at least one barrier structure is formed on the second surface of the substrate 20. Specifically, firstly, a barrier material layer is deposited on the second surface of the substrate. The deposition process includes, but is not limited to, low-pressure chemical vapor deposition (LPCVD), plasma-enhanced chemical vapor deposition (PECVD), or thermal oxidation. The barrier material layer is selected as a dielectric material with a high etch selectivity to the substrate. The material of the barrier material layer can be an oxide, such as silicon dioxide. Subsequently, a patterned photoresist layer is formed on the barrier material layer using a photolithography process. The patterned photoresist layer defines the shape and position of the barrier structure. Using the patterned photoresist layer as a mask, a portion of the barrier material layer is etched away, thereby forming at least one barrier structure on the second surface of the substrate 20. Finally, the photoresist layer is removed. The etching of the barrier material layer can be performed using dry etching, which can be a conventional etching process such as reactive ion etching (RIE), ion beam etching, or plasma etching. Exemplarily, the number of barrier structures can be one, two, three, four, or more, without specific limitation.

[0035] In one example, at least one blocking structure includes a first blocking structure 233 and a second blocking structure 242 spaced apart in a first direction. Specifically, the first blocking structure 233 and the second blocking structure 242 are formed on the second surface of the substrate 20, wherein the dimension of the first blocking structure 233 in the first direction is larger than the dimension of the second blocking structure 242 in the first direction, the thickness of the first blocking structure 233 is greater than the thickness of the second blocking structure 242, and the first direction is perpendicular to the thickness direction of the substrate.

[0036] Specifically, such as Figures 3E to 3H As shown, a first blocking structure 233 and a second blocking structure 242 are formed on the second surface of the substrate 20 at intervals in a first direction, including the following steps: First, a first barrier material layer 231 is formed on the second surface of the substrate 20 (i.e., the second surface of the second substrate 22), and a portion of the first barrier material layer 231 is etched away to form a sub-barrier structure 232 on the second surface of the substrate 20. Specifically, first, the first barrier material layer 231 can be formed using processes including but not limited to thermal oxidation, low-pressure chemical vapor deposition (LPCVD), or plasma-enhanced chemical vapor deposition (PECVD). The first barrier material layer is selected as a dielectric material with a high etch selectivity to the substrate, and the material of the first barrier material layer 231 can be an oxide, such as silicon dioxide. Next, a patterned first photoresist layer is formed on the first barrier material layer 231. The patterned first photoresist layer defines the shape and position of the sub-barrier structure. Using the patterned first photoresist layer as a mask, a portion of the first barrier material layer 231 is etched away to form the sub-barrier structure 232 on the second surface of the substrate 20. Finally, the patterned first photoresist layer is removed. The etching of the first barrier material layer can be performed using dry etching, which can be conventional etching processes such as reactive ion etching (RIE), ion beam etching, or plasma etching.

[0037] Next, a second barrier material layer 241 is formed covering the sub-barrier structure 232 and the second surface of the exposed substrate 20 (i.e., the second surface of the second substrate 22). Specifically, the second barrier material layer 241 is formed on the sub-barrier structure 232 and the exposed second surface of the substrate 20. This can be achieved using processes including, but not limited to, thermal oxidation, low-pressure chemical vapor deposition (LPCVD), and ion-enhanced chemical vapor deposition (PECVD). The material of the second barrier material layer 241 is selected as a dielectric material with a high etching selectivity to the substrate. The material of the second barrier material layer 241 can be an oxide, such as silicon dioxide. The material of the second barrier material layer 241 can be the same as or different from the material of the first barrier material layer 231. For example, the material of the first barrier material layer 231 and the material of the second barrier material layer 241 can be the same, such as silicon dioxide, to ensure good interface compatibility and consistency in subsequent etching.

[0038] Finally, the portion of the second barrier material layer 241 outside the sub-barrier structure 232 is etched away. The remaining second barrier material layer 241 on the second surface of the substrate 20 constitutes the second barrier structure 242. The remaining second barrier material layer 241 on the sub-barrier structure 232 and the sub-barrier structure 232 together constitute the first barrier structure 233. Specifically, firstly, a patterned second photoresist layer is formed on the second barrier material layer 241. This patterned second photoresist layer defines the shape and position of the first barrier structure 233 and the second barrier structure 242. Using the patterned second photoresist layer as a mask, the portion of the second barrier material layer 241 outside the sub-barrier structure 232 is etched away. The remaining second barrier material layer 241 on the second surface serves as the second barrier structure 242. The remaining second barrier material layer 241 on the sub-barrier structure 232 and the sub-barrier structure 232 together serve as the first barrier structure 233. Finally, the patterned photoresist layer is removed. The etching of the second barrier material layer can be performed using dry etching, which can be conventional etching processes such as reactive ion etching (RIE), ion beam etching, or plasma etching.

[0039] For example, a first barrier structure 233 and a second barrier structure 242 are spaced apart on the second surface of the substrate 20 (i.e., the second surface of the second substrate 22) in a first direction. The dimension of the first barrier structure 233 in the first direction is larger than that of the second barrier structure 242 in the first direction, and the thickness of the first barrier structure 233 is greater than that of the second barrier structure 242. The first direction is perpendicular to the thickness direction of the substrate 20, i.e., parallel to the surface of the substrate 20. Because the subsequent etching process has a high selectivity for the substrate and the barrier structures, the substrate region beneath the thicker first barrier structure is more protected during etching, resulting in a relatively slower etching rate. The second barrier structure, being thinner, provides weaker protection to the substrate beneath it, resulting in a faster etching rate. The substrate exposed by the opening is unprotected by any barrier structure, resulting in the fastest etching rate. By rationally designing the thickness and position of each barrier structure, the load effect can be actively compensated during etching, allowing multiple grooves of varying depths to ultimately reach approximately equal depths, improving device stability and reducing process costs.

[0040] In one example, the etching rate of the substrate 20 is higher than that of the first barrier structure 233 and the second barrier structure 242. Specifically, the etching rate of the second substrate 22 is higher than that of the first barrier structure 233 and the second barrier structure 242. Therefore, during the etching process, the areas without barrier structures (the subsequently formed opening regions) or the areas with the second barrier structure 242 are etched rapidly, while the areas with the first barrier structure 233 are etched more slowly due to effective protection. This difference in the thickness of the barrier structures allows for the control of the depth of each groove, ultimately ensuring that the depths of the subsequently formed grooves are approximately equal.

[0041] It is worth mentioning that when it is necessary to form three or more barrier structures with different sizes and / or thicknesses on the second surface of the substrate, the fabrication process can be analogous to the methods described above for forming the first and second barrier structures. Regardless of the number of barrier structures, the core idea is to use barrier structures with different thicknesses and lateral dimensions (i.e., the dimensions of the barrier structures in the first direction) to control the etching of the underlying substrate, thereby achieving a basic consistency in the depth of multiple grooves in subsequent etching processes.

[0042] Then, step S3 is performed to form a first mask layer on the second surface of the substrate exposed outside the barrier structure. An opening is also formed in the first mask layer to expose part of the second surface. The size of the opening in the first direction is smaller than the size of the barrier structure in the first direction.

[0043] In one example, after the barrier structure is fabricated, a first mask layer 25 is formed on the second surface of the substrate 20 exposed outside the barrier structure (i.e., the second surface of the second substrate). The first mask layer 25 does not cover the top surface of the barrier structure, but only covers the second surface of the substrate 20 exposed outside the barrier structure. Subsequently, a pattern is defined on the first mask layer 25 by photolithography, and etching or development is performed to form at least one opening 26. The opening 26 is located in the area outside the barrier structure 242 and exposes the second surface of the substrate 20 below it. The size of the opening 26 in the first direction is smaller than the size of the barrier structure in the first direction.

[0044] In another example, when a first blocking structure 233 and a second blocking structure 242 spaced apart in a first direction are formed on the second surface of the substrate 20, a first mask layer 25 is formed on the second surface of the substrate 20 exposed outside the first blocking structure 233 and the second blocking structure 242. An opening 26 is also formed in the first mask layer 25 to expose a portion of the second surface. The opening 26 is located on the side of the first blocking structure 233 away from the second blocking structure 242. The size of the opening 25 in the first direction is smaller than the size of the second blocking structure 242 in the first direction.

[0045] Specifically, such as Figure 3I As shown, after the fabrication of the first barrier structure 233 and the second barrier structure 242 is completed, a first mask layer 25 is formed on the second surface of the substrate 20 exposed on the outside of the two barriers (i.e., the second surface of the second substrate 22). The first mask layer 25 does not cover the top surfaces of the first barrier structure 233 and the second barrier structure 242, but only covers the second surface of the substrate 20 exposed on the outside of the two barriers. Subsequently, a pattern is defined on the first mask layer 25 by photolithography, and etching or development is performed to form at least one opening 26. The opening 26 is located in the area outside the first barrier structure 233 and the second barrier structure 242. For example, the opening 26 is located on the side of the first barrier structure 233 away from the second barrier structure 242, and exposes the second surface of the substrate 20 below it. The size of the opening 26 in the first direction is smaller than the size of the second barrier structure 242 in the first direction.

[0046] Finally, step S4 is performed, using the first mask layer as a mask, to perform an etching process to etch away the blocking structure and part of the substrate below it to form a blocking area groove, and to etch away the part of the substrate exposed by the opening to form an opening area groove. The remaining substrate between the blocking area groove and the opening area groove forms a comb structure, and the depths of the blocking area groove and the opening area groove are basically equal.

[0047] In one example, the barrier region groove and the opening region groove can be formed by performing two etching processes, with both etching processes using the first mask layer 25. The steps for forming the barrier region groove and the opening region groove include: First, using the first mask layer 25 as a mask, a first etching process is performed to etch away the blocking structure and a portion of the substrate 20 below it (i.e., the blocking structure and a portion of the second substrate 22 below it) to form an initial groove in the blocking region. When multiple blocking structures exist, each blocking structure forms an initial groove in the blocking region. The etching process also removes a portion of the substrate 20 exposed by the opening 26 (i.e., the portion of the second substrate 22 exposed by the opening 26) to form an initial groove 291 in the opening region. Since there is no blocking structure at the opening 26, and the etching rate of the substrate is higher than the etching rate of the blocking material (i.e., the blocking structure), the depth of the initial groove in the blocking region is less than the depth of the initial groove 291 in the opening region at the end of the first etching process.

[0048] Subsequently, using the first mask layer 25 as a mask, a second etching process is performed to further etch the initial grooves 291 of the blocking region and the opening region, thereby increasing their depth. During this stage, the groove areas are all exposed substrate 20, and the etching rate gradually approaches uniformity. However, due to the difference in depth between the initial grooves 291 of the blocking region and the opening region, the depth difference can be gradually reduced by precisely controlling the time and rate of the second etching process, ultimately forming blocking and opening grooves 29 of approximately equal depth. After etching, the unetched substrate portion (i.e., the remaining substrate) between adjacent blocking and opening grooves 29 forms a comb structure. This comb structure has highly consistent tooth height, significantly improving the performance and reliability of the MEMS device. Dry etching can be used to etch the blocking structure and the substrate. Dry etching can be conventional etching processes such as reactive ion etching (RIE), ion beam etching, or plasma etching.

[0049] In another example, when a first blocking structure 233 and a second blocking structure 242 spaced apart in a first direction are formed on the second surface of the substrate 20, an etching process is performed using the first mask layer 25 as a mask to etch away the first blocking structure 233 and a portion of the substrate below it to form a first blocking area groove 27, to etch away the second blocking structure 242 and a portion of the substrate below it to form a second blocking area groove 28, and to etch away the portion of the substrate exposed by the opening to form an opening area groove 29. The remaining substrate between adjacent first blocking area grooves 27 and second blocking area grooves 28, and the remaining substrate between adjacent first blocking area grooves 27 and opening area grooves 29 constitute a comb structure. The depths of the first blocking area groove 27, the second blocking area groove 28, and the opening area groove 29 are substantially equal.

[0050] Specifically, such as Figure 3J and Figure 3K As shown, the first barrier region groove 27, the second barrier region groove 28, and the opening region groove 29 can be formed by performing two etching processes, and the mask for both etching processes is the first mask layer 25. The steps for forming the first barrier region groove 27, the second barrier region groove 28, and the opening region groove 29 include: First, using the first mask layer 25 as a mask, a first etching process is performed to etch away the first blocking structure 233 and a portion of the substrate 20 below it (i.e., the first blocking structure 233 and a portion of the second substrate 22 below it) to form an initial groove 271 for the first blocking region. Then, the second blocking structure 242 and a portion of the substrate 20 below it (i.e., the second blocking structure 242 and a portion of the second substrate 22 below it) are etched away to form an initial groove 281 for the second blocking region. Finally, the portion of the substrate 20 exposed by the opening 26 (i.e., the portion of the second substrate 22 exposed by the opening 26) is etched away to form an initial groove 291 for the opening region. Since the thickness of the first blocking structure 233 is greater than the thickness of the second blocking structure 242, there is no blocking structure at the opening 26, and the etching rate of the substrate is higher than the etching rate of the blocking material (i.e., the first blocking structure and the second blocking structure), at the end of the first etching process, the initial groove 271 of the first blocking region is the shallowest, the initial groove 281 of the second blocking region is the next deepest, and the initial groove 291 of the opening region is the deepest.

[0051] Subsequently, using the first mask layer 25 as a mask, a second etching process is performed to further etch the initial groove 271 of the first blocking region, the initial groove 281 of the second blocking region, and the initial groove 291 of the opening region, thereby increasing their depth. At this stage, all three groove areas are exposed substrates 20, and the etching rates gradually become more consistent. However, because the initial grooves 271, 281, and 291 of the first blocking region have different depths, the depth difference between the three grooves can be gradually reduced by precisely controlling the time and rate of the second etching process, ultimately forming grooves 27, 28, and 29 of the first blocking region with essentially equal depths. After etching, the remaining substrate between the first blocking region groove 27 and the second blocking region groove 28, and the remaining substrate between the first blocking region groove 27 and the opening region groove 29, form a comb-like structure. This comb-like structure has a highly consistent tooth height, significantly improving the performance and reliability of the MEMS device. The etching of the first blocking structure, the second blocking structure, and the substrate can be performed using dry etching, which can be conventional etching processes such as reactive ion etching (RIE), ion beam etching, or plasma etching.

[0052] In other examples, single-step or multi-step etching processes can be selected based on process requirements. With single-step etching, the etching time is precisely controlled, and the etching process is regulated by barrier structures of varying thicknesses, ensuring that the grooves in each region ultimately reach a substantially uniform depth. With multi-step etching, while maintaining the same mask layer, etching is performed in stages. By creating differentiated depths in the initial stage and gradually converging in subsequent stages, the groove depths in each region are made substantially equal.

[0053] It is worth mentioning that when three or more barrier structures are spaced apart in the first direction on the second surface of the substrate, the fabrication process is similar to that of the case with two barrier structures. By reasonably designing the lateral dimensions and thickness of each barrier structure and using single-step or multi-step etching processes, it is still possible to achieve that the final depths of all barrier area grooves and opening area grooves are essentially equal. Those skilled in the art can reasonably set the number, arrangement, and size of the barrier structures according to the actual device requirements.

[0054] In one example, after forming the blocking area groove and the opening area groove 29, the process also includes removing the first mask layer 25. For example, the first mask layer 25 can be removed by ashing or wet process to provide good interface conditions for subsequent processes.

[0055] This concludes the description of the key steps in the fabrication method of the MEMS device of this application. The complete fabrication method of the MEMS device may include other steps, which will not be elaborated here. It is worth mentioning that the order of the above steps can be adjusted without conflict.

[0056] In summary, the MEMS device fabrication method of this application, by setting a barrier structure on the second surface of the substrate and using a smaller opening, effectively overcomes the load effect by utilizing the barrier structure to differentiate the etching process during the etching process. This ensures that the formed barrier area groove and the opening area groove ultimately reach essentially equal depths, effectively guaranteeing the dimensional consistency of the device structure, reducing costs, and improving the performance and reliability of the device.

[0057] This application also provides a MEMS device, which can be prepared by the method described in Embodiment 1 above, or by other suitable preparation methods.

[0058] This application has been described through the above embodiments. However, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit this application to the scope of the described embodiments. Furthermore, those skilled in the art will understand that this application is not limited to the above embodiments, and many more variations and modifications can be made based on the teachings of this application, all of which fall within the scope of protection claimed in this application. The scope of protection of this application is defined by the appended claims and their equivalents.

Claims

1. A method for fabricating a MEMS device, characterized in that, include: A substrate is provided, the substrate having opposing first and second surfaces; At least one barrier structure is formed on the second surface of the substrate; A first mask layer is formed on the second surface of the substrate exposed outside the barrier structure. An opening is also formed in the first mask layer to expose a portion of the second surface. The size of the opening in the first direction is smaller than the size of the barrier structure in the first direction. Using the first mask layer as a mask, an etching process is performed to etch away the blocking structure and a portion of the substrate below it to form a blocking area groove, and to etch away the portion of the substrate exposed by the opening to form an opening area groove. The remaining substrate between the blocking area groove and the opening area groove forms a comb-like structure, and the depths of the blocking area groove and the opening area groove are substantially equal.

2. The preparation method according to claim 1, characterized in that, The process of using the first mask layer as a mask to perform an etching process to etch away the blocking structure and a portion of the substrate below it to form a blocking region groove, and to etch away the portion of the substrate exposed by the opening to form an opening region groove, includes: Using the first mask layer as a mask, a first etching process is performed to etch away the blocking structure and a portion of the substrate below it to form an initial groove in the blocking region, and to etch away the portion of the substrate exposed by the opening to form an initial groove in the opening region, wherein the depth of the initial groove in the blocking region is less than the depth of the initial groove in the opening region. Continuing with the first mask layer as a mask, a second etching process is performed to increase the depth of the initial groove of the blocking region and the initial groove of the opening region, forming the blocking region groove and the opening region groove that extend from the second surface of the substrate into its interior, respectively.

3. The preparation method according to claim 1, characterized in that, The at least one blocking structure includes a first blocking structure and a second blocking structure spaced apart in the first direction. The opening is located on the side of the first blocking structure away from the second blocking structure. The first blocking structure has a larger dimension in the first direction than the second blocking structure in the first direction. The opening has a smaller dimension in the first direction than the second blocking structure in the first direction. The thickness of the first blocking structure is greater than the thickness of the second blocking structure. The first direction is perpendicular to the thickness direction of the substrate. The etching process forms a first blocking area groove, a second blocking area groove, and an opening area groove. The remaining substrate between the first blocking area groove and the second blocking area groove, and the remaining substrate between the first blocking area groove and the opening area groove, constitute the comb tooth structure. The depths of the first blocking area groove, the second blocking area groove, and the opening area groove are substantially equal.

4. The preparation method according to claim 3, characterized in that, Forming the first blocking structure and the second blocking structure includes the following steps: A first barrier material layer is formed on the second surface of the substrate, and a portion of the first barrier material layer is etched away to form a sub-barrier structure on the second surface of the substrate; A second barrier material layer is formed that covers the sub-barrier structure and the second surface of the exposed substrate; The portion of the second barrier material layer outside the sub-barrier structure is etched away. The remaining second barrier material layer on the second surface of the substrate constitutes the second barrier structure. The remaining second barrier material layer on the sub-barrier structure and the sub-barrier structure together constitute the first barrier structure.

5. The preparation method according to claim 3, characterized in that, The etching process has a higher etching rate for the substrate than for the first barrier structure and the second barrier structure.

6. The preparation method according to claim 4, characterized in that, The first barrier material layer and the second barrier material layer have the same material, the first barrier material layer is made of oxide, the second barrier material layer is made of oxide, and the substrate is a silicon substrate.

7. The preparation method according to claim 1, characterized in that, The substrate includes a first substrate and a second substrate, wherein a cavity is formed in the first substrate extending from the surface of the first substrate into its interior. The second substrate has a first surface and a second surface opposite to each other. The first surface of the first substrate, on which the cavity is formed, is joined to the first surface of the second substrate to form the substrate, wherein the second surface of the substrate is the second surface of the second substrate.

8. The preparation method according to claim 7, characterized in that, The steps for forming the cavity include: A patterned second mask layer is formed on the surface of the first substrate; The first substrate is etched using the patterned second mask layer as a mask to form the cavity in the first substrate; Remove the patterned second mask layer.

9. The preparation method according to claim 7, characterized in that, The distance between the cavity and the second surface of the substrate is greater than the distance between the cavity and the first surface of the substrate, and the comb structure is located above the cavity.

10. A MEMS device, characterized in that, The MEMS device is fabricated using the MEMS device fabrication method described in any one of claims 1-9.

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