Miniaturized MEMS pressure sensor
By setting grooves on the substrate of the MEMS pressure sensor and using a dry etching process, the angle between the strain film and the base is ensured, and the problem of large size of the MEMS pressure sensor in the prior art is solved, and a miniaturized design is realized.
Patent Information
- Application Number
- CN202421985956.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-15
- Publication Date
- 2025-05-27
- Estimated Expiration
- 2034-08-15
AI Technical Summary
The existing MEMS pressure sensors have increased the size of the chip due to the anisotropy and bevel etching caused by the wet etching process, making it difficult to achieve a miniaturized design.
By providing grooves on the substrate, a strain film and a base are formed, ensuring that the angle between the strain film and the inner side surface of the base is 90°, and a dry etching process is used to reduce the size of the substrate.
While ensuring the size of the strain film, the structural size of the substrate and the MEMS pressure sensor is reduced, and the sensor is miniaturized.
Smart Images
Figure CN222912941U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of MEMS sensors, and more particularly, to a miniaturized MEMS pressure sensor. Background Art
[0002] MEMS pressure sensors typically use a thin film of Si as the diaphragm for sensing pressure. Piezoresistive strips are implanted on the diaphragm under stress, and their resistance values change with the magnitude of the stress. Then, the change in the piezoresistive strip resistance is reflected in the magnitude of the output voltage through the structure of a Wheatstone bridge. Generally, the back cavity is obtained through a wet microfabrication etching process. The wet processing technology is anisotropic and usually etches into an inclined surface, which will increase the size of the chip. A particularly typical application is the MEMS island pressure sensor. Summary of the Invention
[0003] This application aims to overcome at least one deficiency in the prior art by providing a miniaturized MEMS pressure sensor.
[0004] An embodiment of this application provides a miniaturized MEMS pressure sensor, including:
[0005] A substrate, including a strain film and a base disposed along the edge of the strain film to support the strain film;
[0006] A piezoresistor disposed on the strain film;
[0007] Wherein, the included angle between the inner side surface of the strain film and the base is 90°.
[0008] In the above technical solution, the included angle between the inner side surface of the strain film and the base is 90°, that is, the inner side surface of the base is a straight surface. Compared with the setting method where the inner side surface of the base is an inclined surface, this can minimize the size of the substrate as much as possible while ensuring the size of the strain film, thereby reducing the structural size of the MEMS pressure sensor and facilitating the miniaturized design of the sensor.
[0009] In an alternative embodiment, a groove is provided on one side of the substrate, and the groove forms the strain film and the base of the substrate.
[0010] In an alternative embodiment, the inner surface of the groove is an etched surface.
[0011] In an alternative embodiment, the groove and the piezoresistor are respectively located on opposite sides of the strain film.
[0012] In an alternative embodiment, the substrate is a single-crystalline silicon substrate, a polycrystalline silicon substrate, or an SOI substrate.
[0013] In an alternative embodiment, the number of varistors is plural, and the plural varistors are connected to form a Wheatstone bridge.
[0014] In an alternative embodiment, an island beam is disposed on the back surface of the strain film, and the included angle between the side surface of the island beam and the strain film is 90°.
[0015] In an alternative embodiment, the island beam is a single island or a double island.
[0016] In an alternative embodiment, the island beam is a cross beam structure or a peninsula beam film structure.
[0017] To make the above objects, features, and advantages of the present application more obvious and understandable, the following specific preferred embodiments are given, and in conjunction with the accompanying drawings, the detailed description is as follows. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] To more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the accompanying drawings required for the embodiments. The accompanying drawings are incorporated into the specification and form a part of the specification. These drawings show the embodiments in line with the present application and are used together with the specification to explain the technical solutions of the present application. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.
[0019] Figure 1 Shows a schematic structural diagram of the miniaturized MEMS pressure sensor provided by the embodiment of the present application;
[0020] Figure 2 Shows a schematic structural diagram of the substrate after dry etching provided by the embodiment of the present application;
[0021] Figure 3 Shows a schematic structural diagram of the substrate after wet etching provided by the embodiment of the present application;
[0022] Figure 4 Shows a schematic structural diagram of the substrate after dry etching provided by the embodiment of the present application (including a single island);
[0023] Figure 5 Shows a schematic structural diagram of the substrate after wet etching provided by the embodiment of the present application (including a single island);
[0024] Figure 6 Shows a schematic structural diagram of the substrate after dry etching provided by the embodiment of the present application (including a double island);
[0025] Figure 7Shows a schematic structural diagram of the substrate after wet etching provided by the embodiments of the present application (including double islands);
[0026] Reference numerals:
[0027] 1. Substrate; 11. Groove; 12. Strain film; 13. Base; 14. Island beam; 2. Piezoresistor. Detailed implementation manners
[0028] Now, various exemplary embodiments of the present application will be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present application.
[0029] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary only for explaining the present application and should not be construed as limiting the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.
[0030] The terms "first" and "second" in the description and claims of the present application may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise specified, the meaning of "a plurality" is two or more. In addition, "and / or" in the description and claims means at least one of the connected objects. The character " / " generally indicates an "or" relationship between the associated objects before and after.
[0031] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is 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 orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present application.
[0032] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" 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 mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.
[0033] As Figure 1 shown, the miniaturized MEMS pressure sensor provided by the embodiment of the present application includes: a substrate 1, a detection element, and a groove 11. The substrate 1 has a first surface and a second surface. The detection element is disposed on the first surface. The detection element can be a piezoresistor 2, and the number of piezoresistors 2 can be multiple. The multiple piezoresistors 2 are connected to form a Wheatstone bridge. The groove 11 is disposed on the second surface to form a strain film 12 and a base 13 that is disposed along the edge of the strain film 12 and supports the strain film 12. Wherein, the included angle between the inner side surfaces of the strain film 12 and the base 13 is 90°.
[0034] The actual setting of the groove 11 on the substrate 1 is actually a local thinning design of the substrate 1. This local thinning design enables the substrate 1 to form a strain film 12 and a base 13 that supports the strain film 12. Specifically, the part of the substrate 1 corresponding to the bottom surface of the groove 11 is the strain film 12, and the part of the substrate 1 surrounding the outer periphery of the strain film 12 and the groove 11 is the base 13.
[0035] In the above technical solution, the included angle between the inner side surfaces of the strain film 12 and the base 13 is 90°. That is to say, the inner side surface of the base 13 is a straight surface. Compared with the setting method in which the inner side surface of the base 13 is an inclined surface, this can minimize the size of the substrate 1 as much as possible while ensuring the size of the strain film 12, thereby reducing the structural size of the MEMS pressure sensor and facilitating the realization of the miniaturized design of the sensor.
[0036] In some embodiments, the substrate 1 is made of a single-crystalline silicon substrate, a polycrystalline silicon substrate, or a SOI substrate, etc. Preferably, in this embodiment, the substrate 1 is made of a single-crystalline silicon substrate.
[0037] In some embodiments, the groove 11 is formed by a dry etching process. That is to say, the inner surface of the groove 11 is an etched surface. When specifically setting, the substrate 1 can be etched by deep reactive ion etching (DRIE) to form the groove 11. Among them, the etchant for deep reactive ion etching can use xenon difluoride (XeF2). However, this embodiment does not make any limitation in this regard.
[0038] As Figures 4 - 7As shown, in some embodiments, an island beam 14 is provided on the back surface of the strain film 12. That is to say, the miniaturized MEMS pressure sensor can be a MEMS island-type pressure sensor. However, this embodiment does not make any limitation thereto.
[0039] In some embodiments, the island beam 14 is a single island or a double island. However, this embodiment does not make any limitation thereto.
[0040] In some embodiments, the island beam 14 is a cross beam structure or a peninsula beam 14 film structure. However, this embodiment does not make any limitation thereto.
[0041] In some embodiments, the included angle between the side surface of the island beam 14 and the strain film 12 is 90°. With such a setting, it is also possible to reduce the size of the substrate 1 as much as possible while ensuring the size of the strain film 12, thereby reducing the structural size of the MEMS pressure sensor and facilitating the realization of the miniaturized design of the sensor.
[0042] As Figure 1 shown, on the other hand, the embodiment of the present application also provides a method for manufacturing a miniaturized MEMS pressure sensor, including the following steps:
[0043] Step S100: Provide a substrate 1, and the substrate 1 has a first surface and a second surface;
[0044] Step S200: Form a piezoresistor 2 on the first surface of the substrate 1;
[0045] Step S300: Form an etching window on the second surface of the substrate 1;
[0046] Step S400: Form a groove 11 on the second surface of the substrate 1 to form a strain film 12 and a pedestal 13 for supporting the strain film 12, wherein the included angle between the inner side surfaces of the strain film 12 and the pedestal 13 is 90°.
[0047] The actual setting of the groove 11 on the substrate 1 is a local thinning design of the substrate 1, and this local thinning design enables the substrate 1 to form a strain film 12 and a pedestal 13 for supporting the strain film 12. Specifically, the part of the substrate 1 corresponding to the bottom surface of the groove 11 is the strain film 12, and the part of the substrate 1 surrounding the outer periphery of the strain film 12 and the groove 11 is the pedestal 13.
[0048] In the above technical solution, the included angle between the inner side surfaces of the strain film 12 and the pedestal 13 is 90°, that is to say, the inner side surface of the pedestal 13 is a straight surface. Compared with the setting method in which the inner side surface of the pedestal 13 is an inclined surface, it is possible to reduce the size of the substrate 1 as much as possible while ensuring the size of the strain film 12, thereby reducing the structural size of the MEMS pressure sensor and facilitating the realization of the miniaturized design of the sensor.
[0049] In some embodiments, the substrate 1 is a single-crystalline silicon substrate, a polycrystalline silicon substrate, or an SOI substrate, etc. Preferably, in this embodiment, the substrate 1 is a single-crystalline silicon substrate.
[0050] In some embodiments, the groove 11 is formed by a dry etching process. Specifically, the substrate 1 is etched by deep reactive ion etching (DRIE) to form the groove 11. Among them, the etchant for deep reactive ion etching can use xenon difluoride (XeF2). However, this embodiment does not make any limitation in this regard.
[0051] As Figures 4 - 7 shown, in some embodiments, when the groove 11 is formed on the second surface of the substrate 1, the island beam 14 is also formed on the back surface of the strain film 12. That is to say, the miniaturized MEMS pressure sensor can be a MEMS island-type pressure sensor. However, this embodiment does not make any limitation in this regard.
[0052] In some embodiments, the island beam 14 is a single island or a double island. However, this embodiment does not make any limitation in this regard.
[0053] In some embodiments, the island beam 14 is a cross beam structure or a peninsula beam 14 film structure. However, this embodiment does not make any limitation in this regard.
[0054] In some embodiments, the included angle between the side surface of the island beam 14 and the strain film 12 is 90°. With such a setting, it is also possible to reduce the size of the substrate 1 as much as possible while ensuring the size of the strain film 12, thereby being able to reduce the structural size of the MEMS pressure sensor and being beneficial to realizing the miniaturized design of the sensor.
[0055] For the convenience of understanding, the above-mentioned miniaturized MEMS pressure sensor will be described below by means of experiments. In this experiment, the substrate 1 is etched by two etching methods, dry etching and wet etching, respectively, and the sizes of the obtained strain films 12 are compared.
[0056] The experimental process is as follows:
[0057] 1. Two substrates 1 with equal sizes are respectively defined as the first substrate and the second substrate.
[0058] 2. The first substrate is etched by a dry etching process to obtain a strain film 12 with a length of a and a width of b. As Figure 2 shown, the first substrate after dry etching is shown.
[0059] 3. The second substrate is etched by a wet etching process to obtain a strain film 12 with a length of a and a width of b. As Figure 3 shown, the second substrate after wet etching is shown.
[0060] When etching the substrate 1 using a dry etching process, the side surface of the groove 11 is a straight surface, and the angle between this straight surface and the bottom surface of the groove 11 is approximately 90°. That is to say, the length of the etching window for dry etching is a, and the width is b.
[0061] When etching the substrate 1 using a wet etching process, the side surface of the groove 11 is an inclined surface, and the angle between this inclined surface and the bottom surface of the groove 11 is approximately 54.7°. Define the length of its etching window as c and the width as d. And through calculation, the relationships between c and a, as well as b and d, can be obtained:
[0062]
[0063] t = h 1 -h 2
[0064] where t is the thickness of the strain film, h 1 is the thickness of the substrate, h 2 is the etching depth.
[0065] It can be seen that compared with the etching window required for dry etching, if a strain film of the same size is to be formed, the length of the etching window required for wet etching is and the width is The length and width are increased by
[0066] It can be imagined that when the maximum size of the strain film that can be formed on the first substrate is a×b, if a strain film of the same size is to be formed on the second substrate, it is necessary to increase the size of the second substrate. That is to say, the length and width of the second substrate are increased by
[0067] It can also be imagined that if a strain film 12 of the same size is to be formed on the first substrate and the second substrate, and an island beam 14 is formed on the back surface of the strain film 12, the size of the second substrate will be further increased. For example, as Figure 4 and Figure 5 shown, when forming a single island on the strain film, the length and width of the second substrate are increased by As Figure 6 and Figure 7 shown, when forming a double island on the strain film, the length and width of the second substrate are increased by
[0068] Generally speaking, when ensuring that the size of the strain film 12 is the same, the etching window required for wet etching is larger than that required for dry etching, and the size of the substrate required for wet etching is larger than that required for dry etching. Therefore, making the angle between the inner side surface of the pedestal 13 and the strain film 12 90°, or using dry etching to form the strain film 12, makes the size of the substrate 1 smaller, which is beneficial to realizing the miniaturized design of the sensor.
[0069] On the other hand, an embodiment of the present application further provides a pressure detection device, including the miniaturized MEMS pressure detection sensor described above.
[0070] The ultrasonic detection device according to the embodiment of the present application includes a miniaturized MEMS pressure detection sensor, and the included angle between the strain film and the inner side surface of the base is 90°. That is to say, the inner side surface of the base is a straight surface. Compared with the setting method in which the inner side surface of the base is an inclined surface, this can minimize the size of the base as much as possible while ensuring the size of the strain film, thereby reducing the structural size of the MEMS pressure sensor and facilitating the miniaturized design of the sensor.
[0071] One or more embodiments of this specification are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification shall be included in the protection scope of the present application.
[0072] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present application, and all of them should be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims
1. A miniaturized MEMS pressure sensor, characterized in that: include: A substrate, comprising a strain film and a base arranged along an edge of the strain film and supporting the strain film; A varistor, disposed on the strain film; Wherein, the included angle between the strain film and the inner side surface of the base is 90°.
2. The miniaturized MEMS pressure sensor according to claim 1, characterized in that: A groove is disposed on one side of the substrate, and the groove enables the substrate to form the strain film and the base.
3. The miniaturized MEMS pressure sensor according to claim 2, characterized in that: The inner surface of the groove is an etched surface.
4. The miniaturized MEMS pressure sensor according to claim 2, characterized in that: The groove and the piezoresistor are respectively located on two opposite sides of the strain film.
5. The miniaturized MEMS pressure sensor according to claim 1, characterized in that: The substrate is a single crystal silicon substrate, a polycrystalline silicon substrate or an SOI substrate.
6. The miniaturized MEMS pressure sensor according to claim 1, characterized in that: There are multiple varistors, and the multiple varistors are connected to form a Wheatstone bridge.
7. The miniaturized MEMS pressure sensor according to claim 1, characterized in that: An island beam is arranged on the back of the strain membrane, and the angle between the side surface of the island beam and the strain membrane is 90°.
8. The miniaturized MEMS pressure sensor according to claim 7, characterized in that: The island beam is a single island or a double island.
9. The miniaturized MEMS pressure sensor according to claim 7, characterized in that: The island beam is a cross beam structure or a peninsula beam membrane structure.