MEMS ultrasonic sensor and ultrasonic detection device
By designing the inner wall surface of the base of the arc-surface structure in the MEMS ultrasonic sensor, the problem of reduced mechanical properties after thinning of the film is solved, and the reliability and stability of the sensor are improved.
Patent Information
- Application Number
- CN202421539667.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-01
- Publication Date
- 2025-03-28
- Estimated Expiration
- 2034-07-01
AI Technical Summary
When existing MEMS ultrasonic sensors reduce the film to improve sensitivity, the mechanical properties of the film are reduced, resulting in poor sensor reliability.
By designing the intersection of the inner wall surface of the base and the first surface of the sensitive film as an arc surface, the sensitive film can disperse the pressure in the angular region when it is under pressure, and avoid stress concentration.
The reliability of the MEMS ultrasonic sensor is improved, and stress concentration is avoided, thereby enhancing the stability and performance of the sensor.
Smart Images
Figure CN222684290U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of sensor technology, and in particular to a MEMS ultrasonic sensor and an ultrasonic detection device. Background Art
[0002] MEMS ultrasonic sensors usually use Si thin films as diaphragms for transmitting and receiving ultrasonic signals.
[0003] In existing MEMS ultrasonic sensors, the thinner the film, the higher the sensitivity. However, although thinning the film can improve the sensitivity, the mechanical properties of the film will also decrease, which will lead to poor reliability of the sensor. Utility Model Content
[0004] The embodiments of the present application at least provide a MEMS ultrasonic sensor and an ultrasonic detection device, which can avoid stress concentration in the corner area, thereby helping to improve the reliability of the sensor.
[0005] In a first aspect, an embodiment of the present application provides a MEMS ultrasonic sensor, comprising: a sensitive film having a first surface and a second surface along a thickness direction; a base, arranged on the first surface and arranged along an edge of the pressure sensitive film; a piezoelectric film, arranged on the second surface and configured to be able to convert the deformation of the sensitive film into an electrical signal; wherein the intersection of the inner wall surface of the base and the first surface of the sensitive film is an arc surface.
[0006] In the above scheme, since the intersection of the inner wall surface of the base and the first surface of the sensitive film is an arc surface, the sensitive film can disperse the pressure in the corner area when subjected to pressure, thereby avoiding stress concentration in the corner area, which is beneficial to improving the reliability of the sensor.
[0007] In an optional embodiment, a portion of the inner wall surface of the base is a curved surface.
[0008] In an optional embodiment, the entire inner wall surface of the base is a curved surface.
[0009] In an optional implementation, the arc surface is a spherical surface or an ellipsoidal surface.
[0010] In an optional embodiment, the sensitive film and the base are an integral structure.
[0011] In an optional implementation, the piezoelectric film is a sandwich piezoelectric film.
[0012] In an optional embodiment, the piezoelectric film includes a first electrode layer, a piezoelectric material layer and a second electrode layer in sequence along the thickness direction, wherein the first electrode layer is Al, the piezoelectric material layer is AlN, and the second electrode layer is Mo.
[0013] In a second aspect, an embodiment of the present application further provides an ultrasonic detection device, comprising the MEMS ultrasonic sensor described in any one of the first aspects.
[0014] In the above scheme, since the intersection of the inner wall surface of the base of the MEMS ultrasonic sensor and the first surface of the sensitive film is an arc surface, the sensitive film can disperse the pressure in the corner area when subjected to pressure, thereby avoiding stress concentration in the corner area, which is beneficial to improving the reliability of the sensor.
[0015] In an optional implementation, a processor is further included, and the processor is electrically connected to the MEMS ultrasonic sensor.
[0016] In an optional implementation, a communication module is further included, and the communication module is electrically connected to the MEMS ultrasonic sensor.
[0017] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present application and are used together with the specification to illustrate the technical solutions of the present application. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can also be obtained based on these drawings without creative work.
[0019] Figure 1 A schematic diagram of the structure of a MEMS ultrasonic sensor provided in an embodiment of the present application is shown;
[0020] Figures 2 to 6 The present invention shows a preparation process of a MEMS ultrasonic sensor provided in an embodiment of the present application;
[0021] Figure numerals: 10, sensitive film; 20, base; 30, piezoelectric film; 31, first electrode layer; 32, piezoelectric material layer; 33, second electrode layer; 40, substrate; 50, cavity; 60, cavity. DETAILED DESCRIPTION
[0022] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application.
[0023] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.
[0024] The term "first" or "second" in the specification and claims of this application may include one or more of the features explicitly or implicitly. In the description of this application, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects connected before and after are in an "or" relationship.
[0025] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.
[0026] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0027] The embodiment of the present application provides a MEMS ultrasonic sensor, which can avoid stress concentration in the corner area, thereby helping to improve the reliability of the sensor.
[0028] refer to Figure 1The MEMS ultrasonic sensor provided in the embodiment of the present application includes: a sensitive film 10, a base 20 and a piezoelectric film 30. The sensitive film 10 has a first surface and a second surface along the thickness direction. The base 20 is arranged on the first surface and is arranged along the edge of the pressure sensitive film. The piezoelectric film 30 is arranged on the second surface and is configured to be able to convert the deformation of the sensitive film 10 into an electrical signal. Among them, the intersection of the inner wall surface of the base 20 and the first surface of the sensitive film 10 is an arc surface.
[0029] In the above scheme, since the intersection of the inner wall surface of the base 20 and the first surface of the sensitive film 10 is an arc surface, the sensitive film 10 can disperse the pressure in the corner area when subjected to pressure, thereby avoiding stress concentration in the corner area, which is beneficial to improving the reliability of the sensor.
[0030] In some embodiments, part or the entire inner wall of the base 20 is a curved surface. That is, the inner wall of the base 20 may be set as a curved surface only at a position close to the sensitive film 10, or the entire inner wall of the base 20 may be set as a curved surface. Figure 1 As shown, in this embodiment, the entire inner wall surface of the base 20 is set to be a curved surface.
[0031] In some embodiments, the arc surface may be a spherical surface or an ellipsoidal surface. That is, the arc surface may be a part of a spherical surface or an ellipsoidal surface. Figure 1 As shown, in this embodiment, the entire inner wall surface of the base 20 is set as a part of an ellipsoidal surface.
[0032] In some embodiments, the sensitive film 10 and the base 20 are an integrated structure. That is, the film and the base 20 are different parts of the same structure. For example, the sensitive film 10 and the base 20 supporting the film can be formed by opening a cavity 60 on the surface of the substrate 40, that is, the base 20 is formed at the position surrounding the cavity 60 of the substrate 40, and the remaining part forms the sensitive film 10 disposed on the base 20.
[0033] In some embodiments, the piezoelectric film 30 is a sandwich piezoelectric film 30. That is, the piezoelectric film 30 includes a first electrode layer 31, a piezoelectric material layer 32, and a second electrode layer 33 in sequence along the thickness direction. Figure 1 In the specific configuration, the materials of the first electrode layer 31, the piezoelectric material layer 32 and the second electrode layer 33 can be Al, AlN and Mo respectively. It should be understood that the materials of the first electrode layer 31, the piezoelectric material layer 32 and the second electrode layer 33 can be selected according to actual conditions and are not limited to the above-mentioned methods.
[0034] The embodiment of the present application also provides a method for preparing a MEMS ultrasonic sensor, which is used to prepare the MEMS ultrasonic sensor mentioned above.
[0035] refer to Figures 2 to 6 The method for preparing the MEMS ultrasonic sensor of the embodiment of the present application comprises:
[0036] Step S100: providing a substrate 40, such as Figure 2 shown.
[0037] Step S200: forming a piezoelectric film 30 on the upper surface of the substrate 40, such as Figure 4 shown.
[0038] Step S300, a cavity 60 is etched on the lower surface of the substrate 40, so that the substrate 40 forms a sensitive film 10 and a base 20 surrounding the cavity 60 and supporting the sensitive film 10, wherein the intersection of the inner wall surface of the base 20 and the sensitive film 10 is an arc surface, such as Figure 6 shown.
[0039] In the MEMS ultrasonic sensor prepared according to the above method, the intersection of the inner wall surface of the base 20 and the first surface of the sensitive film 10 is an arc surface, so that the sensitive film 10 can disperse the pressure in the corner area when subjected to pressure, thereby avoiding stress concentration in the corner area, which is beneficial to improving the reliability of the sensor.
[0040] In the above step S100, the substrate 40 may be a silicon wafer. It should be understood that the material and structure of the substrate 40 may be selected according to actual conditions and are not limited to the above-discussed methods.
[0041] In the above step S200, the piezoelectric film 30 may be a sandwich piezoelectric film 30. Figure 3 and Figure 4 As shown, the method for forming a piezoelectric film 30 on the upper surface of a substrate 40 includes: forming a first electrode layer 31 on the upper surface of the substrate 40; forming a piezoelectric material layer 32 on the upper surface of the first electrode layer 31; forming a second electrode layer 33 on the upper surface of the piezoelectric material layer 32; etching and removing a portion of the first electrode layer 31, the piezoelectric material layer 32 and the second electrode layer 33, so that the remaining first electrode layer 31, the piezoelectric material layer 32 and the second electrode layer 33 form a piezoelectric film 30 on the upper surface of the substrate 40.
[0042] In specific configuration, the materials of the first electrode layer 31, the piezoelectric material layer 32 and the second electrode layer 33 can be respectively Al, AlN and Mo. It should be understood that the materials of the first electrode layer 31, the piezoelectric material layer 32 and the second electrode layer 33 can be selected according to actual conditions and are not limited to the above-discussed methods.
[0043] In the above step S300, if Figure 5 and Figure 6As shown, a method for forming a sensitive film 10 on a substrate 40 and a base 20 surrounding a cavity 60 and supporting the sensitive film 10 includes: etching the lower surface of the substrate 40 by deep reactive ion etching (DRIE) to form a cavity 50; etching the inner wall of the cavity 50 by isotropic etching to form a cavity 60, wherein a portion of the substrate 40 surrounding the cavity 60 forms the base 20, and the remaining portion forms the sensitive film 10.
[0044] In a specific configuration, the etchant for isotropic etching may be xenon difluoride (XeF2). It should be understood that the etchant for isotropic etching may be selected according to actual conditions and is not limited to the above-discussed method.
[0045] In some embodiments, part or the entire inner wall of the base 20 is a curved surface. That is, the inner wall of the base 20 may be set as a curved surface only at a position close to the sensitive film 10, or the entire inner wall of the base 20 may be set as a curved surface. Figure 1 As shown, in this embodiment, the entire inner wall surface of the base 20 is set to be a curved surface.
[0046] In some embodiments, the arc surface may be a spherical surface or an ellipsoidal surface. Figure 1 As shown, in this embodiment, the entire inner wall surface of the base 20 is set to be an ellipsoidal surface.
[0047] An embodiment of the present application also provides an ultrasonic detection device, including the MEMS ultrasonic sensor described above.
[0048] The ultrasonic detection device of the embodiment of the present application includes a MEMS ultrasonic sensor. Since the intersection of the inner wall surface of the base 20 of the MEMS ultrasonic sensor and the first surface of the sensitive film 10 is an arc surface, the sensitive film 10 can disperse the pressure in the corner area when subjected to pressure, thereby avoiding stress concentration in the corner area, which is beneficial to improving the reliability of the sensor.
[0049] In some embodiments, the ultrasonic detection device further includes a processor, and the processor is electrically connected to the MEMS ultrasonic sensor. In practical applications, the processor can process the electrical signal to obtain the pressure on the sensitive film 10 .
[0050] In some embodiments, the ultrasonic detection device further includes a communication module, which is electrically connected to the MEMS ultrasonic sensor. In practical applications, the communication module can send an electrical signal to a terminal so that the terminal processes the electrical signal and obtains the pressure on the sensitive film 10 .
[0051] 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 should be included in the scope of protection of this application.
[0052] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.
Claims
1. A MEMS ultrasonic sensor, characterized in that: include: A sensitive film having a first surface and a second surface along a thickness direction; A base, disposed on the first surface and arranged along an edge of the pressure sensitive film; A piezoelectric film, disposed on the second surface and configured to convert the deformation of the sensitive film into an electrical signal; Wherein, the intersection of the inner wall surface of the base and the first surface of the sensitive film is an arc surface.
2. The MEMS ultrasonic sensor according to claim 1, characterized in that: A part of the inner wall surface of the base is a curved surface.
3. The MEMS ultrasonic sensor according to claim 1, characterized in that: The inner wall surface of the base is an entire arc surface.
4. The MEMS ultrasonic sensor according to claim 1, characterized in that: The arc surface is a spherical surface or an ellipsoidal surface.
5. The MEMS ultrasonic sensor according to claim 1, characterized in that: The sensitive film and the base are an integrated structure.
6. The MEMS ultrasonic sensor according to claim 1, characterized in that: The piezoelectric film is a sandwich piezoelectric film.
7. The MEMS ultrasonic sensor according to claim 6, characterized in that: The piezoelectric film includes a first electrode layer, a piezoelectric material layer and a second electrode layer in sequence along the thickness direction, wherein the first electrode layer is Al, the piezoelectric material layer is AlN, and the second electrode layer is Mo.
8. An ultrasonic detection device, characterized in that: The MEMS ultrasonic sensor comprises any one of claims 1-7.
9. The ultrasonic detection device according to claim 8, characterized in that: The device also includes a processor, which is electrically connected to the MEMS ultrasonic sensor.
10. The ultrasonic detection device according to claim 8, characterized in that: It also includes a communication module, which is electrically connected to the MEMS ultrasonic sensor.