Pressure sensor and preparation method thereof

Abstract

The invention provides a pressure sensor and a preparation method thereof, relates to the technical field of semiconductors, and aims to reduce the cost of a device. The pressure sensor comprises a first substrate, a second substrate, a first electrode and a second electrode, the first substrate comprises a first surface and a second surface which are opposite to each other, the first substrate further comprises a cavity, the cavity extends into the first substrate from the first surface, and the cavity comprises a bottom surface close to the second surface. The first electrode is arranged on the bottom surface of the cavity, the second electrode is arranged on the second surface, and the orthographic projection of the second electrode on the second surface is overlapped with the orthographic projection of the first electrode on the second surface. The second substrate is arranged on the first surface and covers the cavity. The pressure sensor can be used for detecting an environment pressure value.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a pressure sensor and a method for preparing the same. Background Art

[0002] Sensors have become indispensable in modern society. Although there are various sensors such as gyroscope sensors, pressure sensors, acceleration sensors, microphones, etc., ultra-small sensors using micro-electro-mechanical system (MEMS) technology are becoming mainstream.

[0003] In particular, pressure sensors are widely used in various fields, including automobiles (oil pressure, suspension pressure), medical (blood pressure), electrical appliances (water level measurement), drones (altitude measurement), etc. However, although pressure sensors are small-sized devices, their structure is relatively complex, making the cost of the device high. Summary of the invention

[0004] The present application proposes a pressure sensor and a method for preparing the same, aiming to reduce the cost of the device.

[0005] To achieve the above objectives, the embodiments of the present application provide the following technical solutions:

[0006] On the one hand, a pressure sensor is provided, the pressure sensor comprising a first substrate, a second substrate, a first electrode and a second electrode, the first substrate comprising a first surface and a second surface opposite to each other, the first substrate further comprising a cavity, the cavity extending from the first surface into the first substrate, the cavity comprising a bottom surface close to the second surface. The first electrode is arranged on the bottom surface of the cavity, the second electrode is arranged on the second surface, and the orthographic projection of the second electrode on the second surface overlaps with the orthographic projection of the first electrode on the second surface. The second substrate is arranged on the first surface and covers the cavity.

[0007] The pressure sensor provided in the embodiment of the present application includes a first substrate and a second substrate, wherein the first substrate has a cavity and the second substrate covers the cavity. The bottom of the cavity is relatively thin and can form a sensing film, and the pressure sensor can be obtained by arranging the first electrode and the second electrode on the upper and lower surfaces of the sensing film.

[0008] Compared with various current pressure sensors, for example, the diffused piezoresistive pressure sensor requires a Wheatstone bridge circuit and the fully enclosed electrostatic capacitance pressure sensor has a relatively complex structure. The pressure sensor in the present application has a simple structure, does not require a relatively complex peripheral circuit, and has a lower device cost.

[0009] In some embodiments, the cavity further includes an inclined side surface, the side surface of the cavity is connected to the bottom surface. The first substrate further includes an air passage, the air passage extends from the first surface into the first substrate, and the air passage is connected to the cavity through the side surface of the cavity.

[0010] In some embodiments, the shape of the orthographic projection of the bottom surface of the cavity on the second surface is a quadrilateral, the cavity includes four inclined side surfaces, the four inclined side surfaces of the cavity correspond one-to-one to and are connected to the four sides of the bottom surface, and the air duct is connected to the cavity through one side surface of the cavity.

[0011] In some embodiments, the pressure sensor further includes an electrode wire, wherein the electrode wire is disposed in the airway and is electrically connected to the first electrode.

[0012] In some embodiments, the air duct includes a bottom surface close to the second surface, the bottom surface of the air duct is connected to the bottom surface of the cavity, and the electrode wire is arranged on the bottom surface of the air duct.

[0013] In some embodiments, the electrode wire is integrally provided with the first electrode.

[0014] In some embodiments, the pressure sensor further includes a pad, which is disposed in the air passage and is electrically connected to the electrode wire.

[0015] In some embodiments, an orthographic projection of the second substrate on the first surface does not overlap with an orthographic projection of the pad on the first surface.

[0016] In some embodiments, the material of the first substrate includes at least one of semiconductor support glass, synthetic quartz glass, quartz glass, heat-resistant glass, crystallized glass, or soda lime glass.

[0017] On the other hand, a method for preparing a pressure sensor is provided, the method comprising: forming a second electrode on a first substrate, the first substrate comprising a first surface and a second surface opposite to each other, the second electrode being located on the second surface; forming a cavity, the cavity extending from the first surface into the first substrate, the cavity comprising a bottom surface close to the second surface; forming a first electrode on the bottom surface of the cavity, the orthographic projection of the first electrode on the second surface overlapping the orthographic projection of the second electrode on the second surface; and arranging a second substrate on the first surface, the second substrate covering the cavity.

[0018] The above-mentioned preparation method of the present application first forms the second electrode on the lower surface of the first substrate, then forms a cavity in the first substrate, and forms the first electrode on the bottom surface of the cavity. Finally, the second substrate is arranged on the first substrate, and the second substrate covers the cavity, so that the pressure sensor can be obtained.

[0019] The pressure sensor has a simple structure, which makes the preparation method simple and the manufacturing time short, which is beneficial to improving production efficiency and reducing production costs.

[0020] In some embodiments, forming the cavity includes: using a femtosecond laser etching process to etch the first surface to form the cavity.

[0021] In some embodiments, a femtosecond laser etching process is used to etch the first surface to form the cavity, and an air channel is also formed during the process. The air channel extends from the first surface into the first substrate, and the air channel is connected to the cavity.

[0022] In some embodiments, during the process of forming the first electrode on the bottom surface of the cavity, an electrode wire is also formed in the air channel, and the electrode wire is electrically connected to the first electrode.

[0023] In some embodiments, during the process of forming the first electrode on the bottom surface of the cavity, an electrode line and a pad are also formed in the air channel, and the first electrode, the electrode line and the pad are electrically connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solution in the present application, the following is a brief introduction to the drawings required for use in some embodiments of the present application. Obviously, the drawings described below are only drawings of some embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams, not the actual size of the product involved in the embodiments of the present application, or the actual process of the method.

[0025] Figure 1A A top view of a pressure sensor provided in an embodiment of the present application;

[0026] Figure 1B for Figure 1A A cross-sectional view of the pressure sensor along the section line AA';

[0027] Figure 1C for Figure 1B Right view of the pressure sensor in FIG.

[0028] Figure 2A to Figure 2C A diagram showing the steps of preparing a second electrode provided in an embodiment of the present application;

[0029] Figure 3A to Figure 3C A diagram showing the steps for preparing a cavity provided in an embodiment of the present application;

[0030] Figure 4A to Figure 4C A diagram showing the steps for preparing a first electrode provided in an embodiment of the present application;

[0031] Figure 5A to Figure 5C A diagram showing the steps of setting a second substrate provided in an embodiment of the present application;

[0032] Figure 6A to Figure 6C A diagram showing the steps of processing a second substrate and setting solder balls provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments provided by the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present application.

[0034] Unless the context requires otherwise, throughout the specification and claims, the term "comprising" is to be construed in an open, inclusive sense, ie, meaning "including, but not limited to."

[0035] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, unless otherwise specified, "plurality" means two or more.

[0036] When describing some embodiments, the term "connection" and its derivative expressions may be used. The term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For example, when describing some embodiments, the term "connection" may be used to indicate that two or more components are in direct physical or electrical contact with each other.

[0037] Additionally, the use of “based on” is meant to be open and inclusive, as a process, step, calculation, or other action “based on” one or more stated conditions or values ​​may, in practice, be based on additional conditions or values ​​beyond those stated.

[0038] It will be understood that when a layer or an element is referred to as being on another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may be present between the layer or element and the other layer or substrate.

[0039] Exemplary embodiments are described herein with reference to cross-sectional views that are idealized exemplary drawings. In the drawings, the thickness of layers and the area of ​​regions are exaggerated for clarity. Therefore, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are contemplated. Therefore, the exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but include deviations in shape due to, for example, manufacturing. For example, an etched region shown as a rectangle will typically have curved features. Therefore, the regions shown in the drawings are schematic in nature, and their shapes are not intended to illustrate the actual shape of regions of the device, and are not intended to limit the scope of the exemplary embodiments.

[0040] An embodiment of the present application provides a pressure sensor, Figure 1A A top view of a pressure sensor provided in an embodiment of the present application; Figure 1B for Figure 1A A cross-sectional view of the pressure sensor along the section line AA'; Figure 1C for Figure 1B Right side view of the pressure sensor in .

[0041] See also Figure 1A to Figure 1C The pressure sensor 1 includes a first substrate 2 and a second substrate 3. The first substrate 2 includes a first surface P1 and a second surface P2 opposite to each other. The first substrate 2 also includes a cavity 4. The cavity 4 extends from the first surface P1 into the first substrate 2. The cavity 4 includes a bottom surface 40 close to the second surface P2. The second substrate 3 is disposed on the first surface P1 of the first substrate 2, and the second substrate 3 covers the cavity 4.

[0042] Exemplarily, the material of the first substrate 2 includes one or more of semiconductor support glass, synthetic quartz glass, quartz glass, heat-resistant glass, crystallized glass or soda lime glass. The material of the second substrate 3 includes one or more of silicon, glass or quartz.

[0043] Exemplarily, the second substrate 3 and the first substrate 2 may be bonded, and the bonding method includes thermal bonding or non-thermal bonding. Alternatively, the second substrate 3 and the first substrate 2 may also be connected by gluing, and the adhesive used includes one or more of polycarbonate (PC), acrylic acid (Acrylic acid), polyvinylchloride (PVC), polyethylene terephthalate (PET), and polypropylene (PP).

[0044] Continue to see Figure 1A to Figure 1CThe pressure sensor 1 further includes a first electrode 5 and a second electrode 6. The first electrode 5 is disposed on the bottom surface 40 of the cavity 4, and the second electrode 6 is disposed on the second surface P2. The orthographic projection of the second electrode 6 on the second surface P2 overlaps with the orthographic projection of the first electrode 5 on the second surface P2.

[0045] It can be understood that, along the direction Z, the distance between the bottom surface 40 of the cavity 4 and the second surface P2 is small, and the portion of the first substrate 2 between the bottom surface 40 of the cavity 4 and the second surface P2 is thinner, and this portion forms a sensing film.

[0046] The first electrode 5 is disposed on the bottom surface 40 of the cavity 4, that is, the first electrode 5 is disposed on the upper surface of the sensing film. The second electrode 6 is disposed on the second surface P2, and the orthographic projection of the second electrode 6 overlaps with that of the first electrode 5, indicating that the second electrode 6 is disposed on the lower surface of the sensing film.

[0047] The external pressure is transmitted to the cavity 4 through the air, and can act on the sensing film to cause the sensing film to deform, which can cause the voltage signals on the first electrode 5 and the second electrode 6 to change. The pressure value to be detected can be obtained by calculating the change value of the voltage signal.

[0048] In the above embodiment of the present application, the pressure sensor 1 includes a first substrate 2 and a second substrate 3, the first substrate 2 has a cavity 4, and the second substrate 3 covers the cavity 4. The bottom of the cavity 4 is relatively thin and can form a sensing film, and the pressure sensor 1 can be obtained by arranging the first electrode 5 and the second electrode 6 on the upper and lower surfaces of the sensing film.

[0049] Compared with various current pressure sensors, for example, the diffused piezoresistive pressure sensor requires a Wheatstone bridge circuit and the fully enclosed electrostatic capacitance pressure sensor has a relatively complex structure. The pressure sensor 1 in the present application has a simple structure, does not require a relatively complex peripheral circuit, and has a lower device cost.

[0050] In some embodiments, see Figure 1A to Figure 1C The cavity 4 further includes an inclined side surface 41, and the side surface 41 of the cavity 4 is connected to the bottom surface 40. The first substrate 2 further includes an air passage 7, and the air passage 7 extends from the first surface P1 of the first substrate 2 to the inside of the first substrate 2, and the air passage 7 is connected to the cavity 4 through the side surface 41 of the cavity 4.

[0051] Exemplarily, one end of the vent 7 penetrates the side surface 41 of the cavity 4 and is connected to the cavity 4 through the side surface 41 of the cavity 4. The other end of the vent 7 can penetrate the side surface 20 of the first substrate 2 and be connected to the outside through the side surface 20 of the first substrate 2. The pressure of the outside world is transmitted to the cavity 4 through the vent 7 with air as the transmission medium, so that it can act on the sensing film.

[0052] Exemplarily, the shape of the positive projection of the bottom surface 40 of the cavity 4 on the second surface P2 is a quadrilateral, the cavity 4 includes four inclined side surfaces 41, the inclination directions of the four side surfaces 41 are different, the four inclined side surfaces 41 of the cavity 4 correspond one-to-one to and are connected to the four edges of the bottom surface 40, and the air duct 7 is connected to the cavity 4 through one side surface 41 of the cavity 4.

[0053] Compared with various current pressure sensors, for example, in the diffused piezoresistive pressure sensor, the air channel is arranged on the second substrate, and the second substrate needs to be etched. In the above-mentioned embodiment of the present application, in the process of etching the first substrate 2 to form the cavity 4, the air channel 7 can be formed simultaneously, and there is no need to etch the second substrate 3 to form the air channel 7, which saves working steps and helps to reduce process costs.

[0054] In some embodiments, see Figure 1A to Figure 1C The pressure sensor 1 also includes an electrode line 8 , which is disposed in the airway 7 and is electrically connected to the first electrode 5 .

[0055] As described above, in the process of etching the first substrate 2 to form the cavity 4, the air duct 7 can be formed simultaneously, and the air duct 7 is connected to the cavity 4. Based on this, in the process of forming the first electrode 5 on the bottom surface 40 of the cavity 4, the electrode line 8 can also be formed in the air duct 7 simultaneously, which can not only realize the electrical connection between the electrode line 8 and the first electrode 5, but also save working steps, which is conducive to reducing process costs.

[0056] Exemplarily, the air duct 7 includes a bottom surface 70 close to the second surface P2, the bottom surface 70 of the air duct 7 is connected to the bottom surface 40 of the cavity 4, and the bottom surface 70 of the air duct 7 and the bottom surface 40 of the cavity 4 have a smooth transition without a step, and the electrode wire 8 is arranged on the bottom surface 70 of the air duct 7, which is conducive to the stable connection between the electrode wire 8 and the first electrode 5.

[0057] Exemplarily, the electrode line 8 is integrally provided with the first electrode 5 , for example, a conductive material is deposited on the bottom surface 40 of the cavity 4 and the bottom surface 70 of the air channel 7 by the same film forming process to form an integrated first electrode 5 and electrode line 8 .

[0058] In some embodiments, see Figure 1A to Figure 1C The pressure sensor 1 also includes a pad 9 , which is disposed in the air passage 7 and is electrically connected to the electrode line 8 .

[0059] It is understandable that in the process of forming the first electrode 5 on the bottom surface 40 of the cavity 4, the electrode line 8 and the pad 9 can also be formed simultaneously in the air channel 7, which can not only realize the electrical connection of the first electrode 5, the electrode line 8 and the pad 9, but also save the working steps, which is conducive to reducing the process cost.

[0060] Exemplarily, the electrode wire 8 is disposed on the bottom surface 70 of the air duct 7 , and the pad 9 is also disposed on the bottom surface 70 of the air duct 7 , which is beneficial to the stable connection between the electrode wire 8 and the pad 9 .

[0061] Exemplarily, the first electrode 5, the electrode line 8 and the pad 9 are integrally arranged, for example, by using the same film forming process to deposit conductive material on the bottom surface 40 of the cavity 4 and the bottom surface 70 of the air channel 7 to form an integral first electrode 5, electrode line 8 and pad 9.

[0062] In some embodiments, see Figure 1A to Figure 1C The orthographic projection of the second substrate 3 on the first surface P1 does not overlap with the orthographic projection of the pad 9 on the first surface P1, that is, the second substrate 3 exposes the pad 9 so as to facilitate setting the solder ball 10 on the pad 9. In addition, the solder ball 10 is also set on the surface of the second electrode 6.

[0063] The embodiment of the present application also provides a method for preparing a pressure sensor. Figure 2A to Figure 2C A diagram showing the steps of preparing a second electrode provided in an embodiment of the present application; Figure 3A to Figure 3C A diagram showing the steps for preparing a cavity provided in an embodiment of the present application; Figure 4A to Figure 4C A diagram showing the steps for preparing a first electrode provided in an embodiment of the present application; Figure 5A to Figure 5C A diagram showing the steps of setting a second substrate provided in an embodiment of the present application; Figure 6A to Figure 6C A diagram showing the steps of processing a second substrate and setting solder balls provided in an embodiment of the present application.

[0064] The method for preparing the pressure sensor includes the following steps S1 to S4:

[0065] S1: See Figure 2A to Figure 2C A second electrode 6 is formed on the first substrate 2 . The first substrate 2 includes a first surface P1 and a second surface P2 that are opposite to each other. The second electrode 6 is located on the second surface P2 .

[0066] Exemplarily, before forming the second electrode 6 on the first substrate 2, synthetic quartz glass is used, and AT cutting is performed on the synthetic quartz glass to obtain the first substrate 2. Then, the first substrate 2 is rinsed with an alkoxy cleaning solution and running water in sequence, for example, the first substrate 2 is cleaned with a solution of sulfuric acid and hydrogen peroxide in a ratio of 1:1, and then the first substrate 2 is rinsed with running water, spin dried, and dried with a cleaning oven.

[0067] Then, the first substrate 2 is placed in a film forming device, and a first conductive layer and a second conductive layer are sequentially stacked on the second surface P2 of the first substrate 2, and the first conductive layer and the second conductive layer are patterned, and the patterned first conductive layer and the second conductive layer together form a second electrode 6, that is, the second electrode 6 has a stacked structure. The material of the first conductive layer may include titanium, and the thickness of the first conductive layer ranges from 10nm to 200nm. The material of the second conductive layer may include aluminum, and the thickness of the second conductive layer ranges from 200nm to 1000nm, or the material of the second conductive layer may also include gold, in which case the thickness of the second conductive layer ranges from 100nm to 800nm.

[0068] S2: See Figure 3A to Figure 3C , forming a cavity 4, the cavity 4 extends from the first surface P1 into the first substrate 2, and the cavity 4 includes a bottom surface 40 close to the second surface P2.

[0069] Exemplarily, a femtosecond laser (Femto Laser) etching process is adopted to etch the first surface P1 of the first substrate 2 to form the cavity 4 in the first surface P1.

[0070] For example, a mask layer is first formed on the first surface P1, and the mask layer exposes the area to be etched in the first surface P1. Then, a femtosecond laser is used to irradiate the area to be etched in the first surface P1, and the material of the first substrate 2 is modified after being irradiated by the femtosecond laser, and can be removed by the etching solution (such as ZE401), thereby forming a cavity 4 in the first surface P1.

[0071] Typically, using conventional etching processes, it takes 300 minutes to etch a substrate with a thickness of 100 μm. In the embodiment of the present application, femtosecond laser etching is used to etch the first substrate 2, and it takes only about 30 minutes to complete the etching to form the cavity 4. The etching rate is improved, the manufacturing process is simplified, the manufacturing time is shortened, and it is beneficial to improve production efficiency.

[0072] Furthermore, the cavity 4 etched by the femtosecond laser etching process has a bottom surface 40 and an inclined side surface 41. The portion of the first substrate 2 between the bottom surface 40 of the cavity 4 and the second surface P2 is relatively thin, and this portion forms a sensing film. When the material of the first substrate 2 includes quartz, since quartz is a d31 mode dielectric material, the electrodes of the pressure sensor need to be arranged on the upper and lower surfaces of the sensing film.

[0073] In some embodiments, see Figure 3A to Figure 3CIn the process of etching the first surface P1 to form the cavity 4 by using the femtosecond laser etching process, an air channel 7 is also formed, the air channel 7 extends from the first surface P1 to the first substrate 2, and the air channel 7 is connected to the cavity 4. The external pressure is transmitted to the cavity 4 through the air channel 7 with air as the transmission medium, so that it can act on the sensing film.

[0074] Exemplarily, one end of the air duct 7 penetrates a side surface 41 of the cavity 4 and is connected to the cavity 4 through the side surface 41 of the cavity 4. The slope of the bottom surface 70 of the air duct 7 is smaller than the slope of the side surface 41 of the cavity 4, which is conducive to forming a continuous electrode line on the bottom surface 70 of the air duct 7.

[0075] S3: See Figure 4A to Figure 4C , a first electrode 5 is formed on the bottom surface 40 of the cavity 4 , and an orthographic projection of the first electrode 5 on the second surface P2 overlaps with an orthographic projection of the second electrode 6 on the second surface P2 .

[0076] It can be understood that the first electrode 5 is formed on the bottom surface 40 of the cavity 4, that is, the first electrode 5 is formed on the upper surface of the sensing film. The second electrode 6 is formed on the second surface P2, and the orthographic projection of the second electrode 6 overlaps with that of the first electrode 5, indicating that the second electrode 6 is formed on the lower surface of the sensing film.

[0077] For example, a conductive layer may be first formed on the first substrate 2, and then a photoresist layer may be formed on the conductive layer, and the photoresist layer may be exposed and developed to form a through opening in the photoresist layer. The conductive layer may be etched through the opening of the photoresist layer, and the portion of the conductive layer remaining may be the first electrode 5. Finally, the remaining photoresist may be stripped off, and the first substrate 2 may be cleaned.

[0078] In some embodiments, see Figure 4A to Figure 4C In the process of forming the first electrode 5 on the bottom surface 40 of the cavity 4, the electrode line 8 is also formed in the air channel 7, which can not only realize the electrical connection between the first electrode 5 and the electrode line 8, but also save steps, which is conducive to reducing the process cost.

[0079] Exemplarily, the bottom surface 70 of the air duct 7 is connected to the bottom surface 40 of the cavity 4, and the slope of the bottom surface 70 of the air duct 7 is smaller than the slope of the side surface 41 of the cavity 4. The bottom surface 70 of the air duct 7 and the bottom surface 40 of the cavity 4 have a smooth transition without any discontinuity. The electrode wire 8 is arranged on the bottom surface 70 of the air duct 7, which is conducive to the stable connection between the electrode wire 8 and the first electrode 5.

[0080] For example, the electrode wire 8 is formed integrally with the first electrode 5 .

[0081] In some embodiments, see Figure 4A to Figure 4CIn the process of forming the first electrode 5 on the bottom surface 40 of the cavity 4, the electrode line 8 and the pad 9 are also formed in the air channel 7, which can not only realize the electrical connection of the first electrode 5, the electrode line 8 and the pad 9, but also save the process and help reduce the process cost.

[0082] Exemplarily, the first electrode 5 , the electrode line 8 and the pad 9 are integrally formed.

[0083] S4: See Figure 5A to Figure 5C A second substrate 3 is disposed on the first surface P1, and the second substrate 3 covers the cavity 4. In addition, the second substrate 3 also covers the top of the vent 7, and the end of the vent 7 can penetrate the side 20 of the first substrate 2 and communicate with the outside through the side 20 of the first substrate 2.

[0084] Exemplarily, the second substrate 3 and the first substrate 2 may be bonded to each other, or the second substrate 3 and the first substrate 2 may be bonded to each other.

[0085] In some embodiments, see Figure 6A to Figure 6C After the second substrate 3 is arranged on the first surface P1, the second substrate 3 is cut so that the orthographic projection of the second substrate 3 on the first surface P1 does not overlap with the orthographic projection of the pad 9 on the first surface P1, that is, the second substrate 3 exposes the pad 9.

[0086] Then, a solder ball 10 is disposed on the pad 9 , and a solder ball 10 is also disposed on the surface of the second electrode 6 , so that the pressure sensor 1 is completed.

[0087] In the above-mentioned preparation method of the present application, the second electrode 6 is first formed on the lower surface of the first substrate 2, and then the cavity 4 is formed in the first substrate 2, and the first electrode 5 is formed on the bottom surface 40 of the cavity 4. Finally, the second substrate 3 is arranged on the first substrate 2, and the second substrate 3 covers the cavity 4, and the pressure sensor 1 can be obtained.

[0088] The pressure sensor 1 has a simple structure, which makes the preparation method simple and the manufacturing time short, thus being beneficial to improving production efficiency and reducing production costs.

[0089] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that a person skilled in the art can think of within the technical scope disclosed in the present application 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 pressure sensor, characterized in that: include: A first substrate, comprising a first surface and a second surface opposite to each other; the first substrate further comprising a cavity, the cavity extending from the first surface into the first substrate, the cavity comprising a bottom surface close to the second surface; A first electrode and a second electrode, wherein the first electrode is disposed on the bottom surface of the cavity, the second electrode is disposed on the second surface, and an orthographic projection of the second electrode on the second surface overlaps with an orthographic projection of the first electrode on the second surface; The second substrate is disposed on the first surface and covers the cavity.

2. The pressure sensor according to claim 1, characterized in that: The cavity further comprises an inclined side surface, and the side surface of the cavity is connected to the bottom surface; The first substrate further includes an air passage extending from the first surface into the first substrate, and the air passage is connected with the cavity through a side surface of the cavity.

3. The pressure sensor according to claim 2, characterized in that: The shape of the orthographic projection of the bottom surface of the cavity on the second surface is a quadrilateral, and the cavity includes four inclined side surfaces, and the four inclined side surfaces of the cavity correspond to and are connected with the four sides of the bottom surface one by one; The airway is communicated with the cavity through a side surface of the cavity.

4. The pressure sensor according to claim 2, characterized in that: The pressure sensor further includes an electrode wire, which is disposed in the airway and is electrically connected to the first electrode.

5. The pressure sensor according to claim 4, characterized in that: The vent includes a bottom surface close to the second surface, and the bottom surface of the vent is connected to the bottom surface of the cavity; The electrode wire is arranged on the bottom surface of the airway.

6. The pressure sensor according to claim 4 or 5, characterized in that: The electrode wire is integrally arranged with the first electrode.

7. The pressure sensor according to claim 4, characterized in that: The pressure sensor further includes a pad, which is disposed in the air passage and is electrically connected to the electrode line.

8. The pressure sensor according to claim 7, characterized in that: The orthographic projection of the second substrate on the first surface does not overlap with the orthographic projection of the pad on the first surface.

9. The pressure sensor according to claim 1, characterized in that: The material of the first substrate includes at least one of semiconductor supporting glass, synthetic quartz glass, quartz glass, heat-resistant glass, crystallized glass, or soda lime glass.

10. A method for preparing a pressure sensor, characterized in that: include: forming a second electrode on a first substrate, wherein the first substrate comprises a first surface and a second surface opposite to each other, and the second electrode is located on the second surface; forming a cavity, the cavity extending from the first surface into the first substrate, the cavity including a bottom surface close to the second surface; forming a first electrode on the bottom surface of the cavity, wherein an orthographic projection of the first electrode on the second surface overlaps with an orthographic projection of the second electrode on the second surface; A second substrate is disposed on the first surface, and the second substrate covers the cavity.

11. The preparation method according to claim 10, characterized in that: Forming the cavity comprises: The first surface is etched using a femtosecond laser etching process to form the cavity.

12. The preparation method according to claim 11, characterized in that: Using a femtosecond laser etching process to etch the first surface, and in the process of forming the cavity, an air passage is also formed; The vent extends from the first surface into the first substrate, and the vent is communicated with the cavity.

13. The preparation method according to claim 12, characterized in that: In the process of forming the first electrode on the bottom surface of the cavity, an electrode wire is also formed in the air passage, and the electrode wire is electrically connected to the first electrode.

14. The preparation method according to claim 12, characterized in that: In the process of forming the first electrode on the bottom surface of the cavity, an electrode line and a pad are also formed in the air passage, and the first electrode, the electrode line and the pad are electrically connected.

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