A pressure sensor

Abstract

The present invention discloses a pressure sensor, comprising a substrate, on which a first sensitive film, a first vacuum cavity, a second sensitive film, and a second vacuum cavity are sequentially arranged. The area of the first sensitive film is larger than that of the second sensitive film, and a protrusion structure located in the first vacuum cavity is arranged on the first sensitive film or the second sensitive film; a first piezoresistor connected to the first sensitive film is arranged around the first sensitive film; and a second piezoresistor connected to the second sensitive film is arranged around the second sensitive film. When operating in a low range, the first sensitive film deforms, the first sensitive film and the second sensitive film do not contact each other, and the second sensitive film does not deform. There is an output in the low range and no output in the high range. When operating in a high range, after the first sensitive film deforms, the first sensitive film and the second sensitive film contact each other under the action of the protrusion structure, the second sensitive film deforms, and the sensor has an output in the high range. It can be seen that the sensor of the present invention can measure dual ranges, thereby reducing the cost and space of the applied equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a pressure sensor. Background Art

[0002] A barometric pressure sensor is a device used to measure ambient air pressure and is currently widely used in consumer electronics. Depending on the application scenario, a barometric pressure sensor can be used to detect ambient atmospheric pressure (used to calculate altitude) or water pressure (used to calculate diving depth). However, ambient atmospheric pressure and water pressure have two completely different measurement ranges. The ambient air pressure range is typically 30kPa to 110kPa, while the water pressure range is generally 110kPa to 700kPa, depending on the water depth.

[0003] If current terminal devices want to support two measurement ranges at the same time, they must use two pressure sensors, namely an atmospheric pressure sensor and a water depth sensor. However, the cost of setting up terminal devices with two sensors is high, and the two sensors occupy a large space, which is not conducive to the application of terminal devices in small-volume scenarios. Summary of the Invention

[0004] In view of the above-mentioned deficiencies, the technical problem to be solved by the present invention is to provide a pressure sensor capable of measuring dual ranges, thereby reducing the cost and space of the applied equipment.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A pressure sensor includes a substrate, on which a first sensitive film, a first vacuum cavity, a second sensitive film, and a second vacuum cavity are sequentially arranged, wherein the area of the first sensitive film is larger than the area of the second sensitive film, and a protrusion structure located in the first vacuum cavity is provided on the first sensitive film or the second sensitive film; a first piezoresistor connected to the first sensitive film is provided around the first sensitive film; and a second piezoresistor connected to the second sensitive film is provided around the second sensitive film.

[0007] Preferably, the protruding structure is provided on a side of the first sensitive film facing the first vacuum chamber.

[0008] Preferably, the center lines of the first sensitive film and the second sensitive film are arranged to coincide with each other.

[0009] Preferably, the center lines of the first sensitive film, the first vacuum chamber, the second sensitive film and the second vacuum chamber are arranged to coincide with each other.

[0010] Preferably, there are four first varistors, and the four first varistors are evenly distributed.

[0011] Preferably, each of the first piezoresistors is located directly above the edge of the first vacuum chamber.

[0012] Preferably, there are four second varistors, and the four second varistors are evenly distributed.

[0013] Preferably, each of the second piezoresistors is located directly above the edge of the second vacuum chamber.

[0014] A preferred embodiment is that the substrate includes a first silicon wafer, a bonding layer, and a second silicon wafer fixed together by an SOI wafer bonding process; the second vacuum cavity is formed on the second silicon wafer by an etching process, and then the second sensitive film is formed on the second vacuum cavity by an SOI wafer bonding process, and a varistor is doped on the second sensitive film to form the second varistor; the first vacuum cavity is formed on the first silicon wafer by an etching process, and then the first sensitive film is formed on the first vacuum cavity by an SOI wafer bonding process, and a varistor is doped on the first sensitive film to form the first varistor.

[0015] Preferably, pads are further provided on the surface of the substrate, and the pads are respectively connected to the first varistor and the second varistor.

[0016] After adopting the above technical solution, the beneficial effects of the present invention are:

[0017] The pressure sensor of the present invention includes a substrate, on which a first sensitive film, a first vacuum cavity, a second sensitive film, and a second vacuum cavity are sequentially arranged. The area of the first sensitive film is larger than that of the second sensitive film. A protrusion structure located in the first vacuum cavity is arranged on the first sensitive film or the second sensitive film. A first piezoresistor connected to the first sensitive film is arranged around the first sensitive film; and a second piezoresistor connected to the second sensitive film is arranged around the second sensitive film. When the sensor operates in a low range, the first sensitive film deforms, and the protrusion structure does not allow the first and second sensitive films to contact each other. At this time, the second sensitive film does not deform, and the sensor has no output in the high range but has output in the low range. When the sensor operates in a high range, after the first sensitive film deforms, the first and second sensitive films come into contact under the action of the protrusion structure and deform due to pressure. At this time, the sensor has output in the high range. It can be seen that the sensor of the present invention can measure dual ranges, thereby reducing the cost and space of the applied equipment.

[0018] Since the protruding structure is provided on the side of the first sensitive film facing the first vacuum chamber, processing and manufacturing are facilitated.

[0019] Since the center lines of the first sensitive film and the second sensitive film are arranged to coincide, data of both ranges can be accurately detected.

[0020] Since the center lines of the first sensitive film, the first vacuum cavity, the second sensitive film and the second vacuum cavity are arranged to coincide with each other, processing and manufacturing are facilitated, and the accuracy of data detection is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 1 is a schematic diagram of the pressure sensor of the present invention when it is working;

[0022] Figure 2 This is a circuit diagram of the pressure sensor of the present invention;

[0023] Figure 3 Schematic diagram of the processing flow of the pressure sensor of the present invention;

[0024] In the figure: 1-substrate, 10-first silicon wafer, 11-second silicon wafer, 2-Bonding layer, 3-first sensitive film, 4-second sensitive film, 5-first piezoresistor, 6-second piezoresistor, 7-first vacuum chamber, 8-second vacuum chamber. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0026] like Figure 1 and Figure 2 As shown, a pressure sensor includes a substrate 1, on which are sequentially arranged a first sensitive film 3, a first vacuum cavity 7, a second sensitive film 4, and a second vacuum cavity 8. The area of the first sensitive film 3 is larger than that of the second sensitive film 4, and a protrusion structure located in the first vacuum cavity 7 is provided on the first sensitive film 3 or the second sensitive film 4. A first piezoresistor 5 connected thereto is provided around the first sensitive film 3, and a second piezoresistor 6 connected thereto is provided around the second sensitive film 4. The piezoresistors of the two layers of sensitive films are connected to form a Wheatstone resistance bridge. In this embodiment, solder pads are also provided on the surface of the substrate 1, which are respectively connected to the first piezoresistor 5 and the second piezoresistor 6. The solder pads may include an output terminal OUT1 and an output terminal OUT2.

[0027] When the sensor operates in a low range, such as 30-110 kPa, under the action of external pressure, the first sensitive film 3 is deformed. Since the external pressure is small, the deformation of the first sensitive film 3 is not enough to contact the second sensitive film 4 through the protruding structure. At this time, the second sensitive film 4 does not deform. The output terminal OUT1 corresponding to the low range of the sensor outputs a voltage signal, and the output terminal OUT2 corresponding to the high range does not output a voltage signal. For circuit principle, see Figure 2One end of the first piezoresistors R1 and R2 is connected to the positive electrode of the power supply V, and one end of the first piezoresistors R3 and R4 is connected to the negative electrode of the power supply V. After the first sensitive film 3 is deformed, the voltage signal output by the output terminal OUT1 corresponds to the magnitude of the external pressure. That is, by reading the voltage signal output by the output terminal OUT1, the ambient air pressure can be detected.

[0028] When the sensor is working in the high range, such as 110~700kPa, the first sensitive film 3 is deformed due to the large external pressure, which drives the protrusion structure to contact the second sensitive film 4. The second sensitive film 4 is deformed due to the pressure, so that the output terminal OUT2 corresponding to the high range has a voltage signal output. Figure 2 One end of the second piezoresistors R5 and R6 is connected to the positive electrode of the power supply V, and one end of the second piezoresistors R7 and R8 is connected to the negative electrode of the power supply V. After the second sensitive film 4 is deformed, the voltage signal output by the output terminal OUT2 corresponds to the water pressure. That is, by reading the voltage signal output by the output terminal OUT2, the water pressure can be detected.

[0029] In summary, the pressure sensor of the present invention can measure dual ranges, thereby reducing the cost and space of the applied equipment.

[0030] like Figure 1 As shown, a protruding structure is provided on the side of the first sensitive film 3 facing the first vacuum chamber 7. Of course, the protruding structure can be provided on the side of the second sensitive film 4 located on the first vacuum chamber 7. The protruding structure provided on the first sensitive film 3 facilitates processing and manufacturing, further reducing costs.

[0031] like Figure 1 As shown, the centerlines of the first sensitive film 3 and the second sensitive film 4 coincide with each other. In a preferred embodiment, the centerlines of the first sensitive film 3, the first vacuum chamber 7, the second sensitive film 4, and the second vacuum chamber 8 coincide with each other, and the raised structures are symmetrically arranged about the first sensitive film 3. With this structure, the first and second sensitive films 3, 4 deform evenly under external forces, improving data acquisition accuracy while also facilitating manufacturing and reducing costs.

[0032] like Figure 2 As shown, there are four first piezoresistors 5, which are evenly distributed. In a preferred embodiment, each first piezoresistors 5 is located directly above the edge of the first vacuum chamber 7. Simultaneously, there are four second piezoresistors 6, which are evenly distributed. In a preferred embodiment, each second piezoresistors 6 is located directly above the edge of the second vacuum chamber 8. The evenly distributed piezoresistors enable accurate data acquisition, facilitate manufacturing, and reduce processing costs.

[0033] like Figure 3As shown, the pressure sensor in this embodiment can adopt the following process:

[0034] The first step is to form a second vacuum chamber 8 on the second silicon wafer 11 by an etching process;

[0035] In the second step, the first silicon wafer 10, the bonding layer 2 and the second silicon wafer 11 are fixed together using the SOI wafer bonding process;

[0036] Step 3: After bonding, a second sensitive film 4 is formed on the second vacuum chamber 8;

[0037] Step 4: doping the second sensitive film 4 with a varistor to form a second varistor 6;

[0038] Step 5: forming a first vacuum chamber 7 on the first silicon wafer 10 by etching;

[0039] Step 6: Using the SOI wafer bonding process, a first sensitive film 3 is formed on the first vacuum chamber 7;

[0040] In the seventh step, the first sensitive film 3 is doped with a varistor to form a first varistor 5 .

[0041] The above-mentioned preferred embodiments of the present invention are only intended to limit the present invention. Any modifications made within the spirit and principles of the present invention, improvements to the same pressure sensor, etc., should be included in the scope of protection of the present invention.

Claims

1. A pressure sensor comprising a substrate, characterized in that: A first sensitive film, a first vacuum cavity, a second sensitive film, and a second vacuum cavity are sequentially provided on the substrate, wherein the area of the first sensitive film is larger than that of the second sensitive film, and a protrusion structure located in the first vacuum cavity is provided on the first sensitive film or the second sensitive film; A first piezoresistor connected to the first sensitive film is provided around the first sensitive film; A second piezoresistor connected to the second sensitive film is provided around the second sensitive film; The first piezoresistor and the second piezoresistor are connected to form a Wheatstone resistance bridge; A pad is further provided on the surface of the substrate, and the pad includes an output terminal OUT1 and an output terminal OUT2, wherein the output terminal OUT1 is electrically connected to the first varistor, and the output terminal OUT2 is electrically connected to the second varistor; When the range is low, the output terminal OUT1 outputs a voltage signal corresponding to the external pressure, and when the range is high, the output terminal OUT2 outputs a voltage signal corresponding to the external pressure.

2. The pressure sensor according to claim 1, wherein The protruding structure is provided on a side of the first sensitive film facing the first vacuum chamber.

3. The pressure sensor according to claim 1, wherein The center lines of the first sensitive film and the second sensitive film are arranged to coincide with each other.

4. The pressure sensor according to claim 3, characterized in that The center lines of the first sensitive film, the first vacuum chamber, the second sensitive film and the second vacuum chamber are arranged to coincide with each other.

5. The pressure sensor according to claim 1, wherein There are four first varistors, and the four first varistors are evenly distributed.

6. The pressure sensor according to claim 5, characterized in that Each of the first piezoresistors is located directly above the edge of the first vacuum chamber.

7. The pressure sensor according to claim 1, wherein There are four second varistors, and the four second varistors are evenly distributed.

8. The pressure sensor according to claim 7, characterized in that Each of the second piezoresistors is located directly above the edge of the second vacuum cavity.

9. The pressure sensor according to any one of claims 1 to 8, characterized in that: The substrate comprises a first silicon wafer, a bonding layer and a second silicon wafer fixed together by an SOI wafer bonding process; forming the second vacuum cavity on the second silicon wafer by an etching process, forming the second sensitive film on the second vacuum cavity by an SOI wafer bonding process, and doping a varistor on the second sensitive film to form the second varistor; The first vacuum cavity is formed on the first silicon wafer by using an etching process, and the first sensitive film is formed on the first vacuum cavity by using an SOI wafer bonding process. A varistor is doped on the first sensitive film to form the first varistor.

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