MEMS absolute pressure sensor

Abstract

An MEMS absolute pressure sensor comprises a substrate, a middle insulation isolation layer, a through hole layer, an insulation packaging layer, a sensor film layer used for sensing pressure and a conductive material assembly used for being connected with the sensor film layer. The substrate is provided with a groove; the sensor film layer is a substrate of the groove and is supported by the middle insulation isolation layer; the sensor film layer is connected between the substrate and the middle insulation isolation layer; the sensor film layer is provided with a piezoresistive resistor, and the sensor film layer is connected with the conductive material assembly through the piezoresistive resistor. The middle insulation isolation layer is connected with the through hole layer, and the through hole layer is connected with the insulation packaging layer; an opening of the sensor film layer is formed in the middle insulation isolation layer through photoetching; a vacuum cavity communicated with the opening is formed in the through hole layer; and the vacuum cavity is positioned between the sensor film layer and the through hole layer. The MEMS absolute pressure sensor provided by the utility model has the advantages of larger measurement range, higher sensitivity and corrosion resistance.

Description

Technical Field

[0001] The utility model relates to a sensor, in particular to a MEMS absolute pressure sensor. Background Art

[0002] Pressure sensors are widely used in fields such as automobiles, medical treatment, and aerospace. Its basic principle is to convert the change in pressure or the change value during deformation into an electrical signal. There are mainly two types of MEMS pressure sensors: piezoresistive and capacitive. Currently, the mainstream MEMS pressure sensor is based on the principle of piezoresistive resistors, that is, a piezoresistive pressure sensor, which is widely used in automotive systems to measure airbag pressure, fuel pressure, engine oil pressure, intake pipe pressure, etc. However, traditional pressure sensors have problems and defects such as a small measurement range, low sensitivity, and easy corrosion, which limit their applications. With the development of science and technology and the expansion of the market demand for MEMS, it is imperative to solve the existing problems. Summary of the Utility Model

[0003] The utility model aims to solve the technical problem of providing a MEMS absolute pressure sensor with a larger measurement range, higher sensitivity, and corrosion resistance.

[0004] To solve the above technical problems, a technical solution for a MEMS absolute pressure sensor of the utility model is as follows:

[0005] It includes a substrate, and also includes an intermediate insulating isolation layer, a via layer, an insulating encapsulation layer, a sensor film layer for sensing pressure, and a conductive material component for connecting the sensor film layer. The substrate is provided with a groove. The sensor film layer is the base of the groove and is supported by the intermediate insulating isolation layer. The sensor film layer is connected between the substrate and the intermediate insulating isolation layer. The sensor film layer is provided with piezoresistive resistors, and the sensor film layer is connected to the conductive material component through the piezoresistive resistors. The intermediate insulating isolation layer is connected to the via layer, and the via layer is connected to the insulating encapsulation layer. The intermediate insulating isolation layer is etched by photolithography to form an opening for the sensor film layer. A vacuum cavity communicating with the opening is formed on the via layer. The vacuum cavity is located between the sensor film layer and the via layer.

[0006] The size of the vacuum cavity is larger than the size of the bottom of the groove.

[0007] The substrate adopts an SO1 silicon substrate, and the thickness of the top silicon is 20 - 80 um.

[0008] The length of the piezoresistive resistor is 150 - 250 um, the width is 10 - 20 um, and the depth is 2 - 5 um.

[0009] The sensor film layer is square, with a side length of 600 - 900 um and a thickness of 20 - 80 um.

[0010] The vacuum cavity is formed by bonding with the substrate through a via layer.

[0011] The intermediate insulating isolation layer is composed of one or more combinations of S102 or SIN thin films, with a thickness of 1 - 5 μm.

[0012] The insulating encapsulation layer is filled with an organic epoxy organic substance.

[0013] The via layer is made of silicon material, with a thickness of 200 - 600 μm and a vacuum cavity depth of 30 - 100 μm.

[0014] The technical effects that the present utility model can achieve are as follows: In a MEMS absolute pressure sensor of the present utility model, by setting a vacuum cavity between the sensor film layer and the via layer, the sensor film layer is more likely to deform due to the setting of the vacuum cavity, and the sensitivity of the pressure sensor is higher. Also, due to the setting of the vacuum cavity, when the sensor film layer is pressurized, the vacuum cavity can play a certain buffering role, and the sensor film layer can withstand a relatively greater pressure, and the measurement range of the pressure sensor is also relatively larger. The present utility model also has an intermediate insulating isolation layer, a via layer, and an insulating encapsulation layer to protect the sensor, making it more corrosion-resistant. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following further elaborates on the present utility model in conjunction with the drawings and specific embodiments:

[0016] Figure 1 It is a schematic structural diagram of a MEMS absolute pressure sensor of the present utility model. SPECIFIC EMBODIMENTS

[0017] The following further elaborates on the present utility model in conjunction with the drawings.

[0018] Refer to Figure 1 .

[0019] A MEMS absolute pressure sensor includes a substrate 1, and also includes an intermediate insulating isolation layer 2, a via layer 7, an insulating encapsulation layer 9, a sensor film layer 3 for sensing pressure, and a conductive material assembly 4 for connecting the sensor film layer 3. Preferably, the substrate uses a SO1 silicon substrate, and the thickness of the top silicon is 20 - 80 μm. The sensor film layer 3 is square, with a side length of 600 - 900 μm and a thickness of 20 - 80 μm. The intermediate insulating isolation layer 2 is composed of one or more combinations of S102 or SIN thin films, with a thickness of 1 - 5 μm. The insulating encapsulation layer 9 is filled with an organic epoxy organic substance. The via layer 7 is made of silicon material, with a thickness of 200 - 600 μm and a vacuum cavity 10 depth of 30 - 100 μm.

[0020] The substrate 1 is provided with a groove 5. The sensor film layer 3 serves as the base of the groove 5 and is supported by the intermediate insulating isolation layer 2. The sensor film layer 3 is connected between the substrate 1 and the intermediate insulating isolation layer 2. The sensor film layer 3 is provided with piezoresistive resistors 6, and the sensor film layer 3 is connected to the conductive material component 4 through the piezoresistive resistors 6. Preferably, the length of the piezoresistive resistor 6 is 150 - 250 um, the width is 10 - 20 um, and the depth is 2 - 5 um. The intermediate insulating isolation layer 2 is connected to the via hole layer 7, and the via hole layer 7 is connected to the insulating encapsulation layer 9. The intermediate insulating isolation layer 2 is etched by photolithography to form an opening 8 of the sensor film layer 3. A vacuum cavity 10 communicating with the opening 8 is formed on the via hole layer 7, and the vacuum cavity 10 is located between the sensor film layer 3 and the via hole layer 7. Specifically, the size of the vacuum cavity 10 is larger than the size of the bottom of the groove 5, and the vacuum cavity 10 is formed by bonding the via hole layer 7 and the substrate 1. By setting the vacuum cavity 10 between the sensor film layer 3 and the via hole layer 7 in the present utility model, the sensor film layer 3 is more likely to deform due to the setting of the vacuum cavity 10, and the sensitivity of the pressure sensor is higher. Moreover, due to the setting of the vacuum cavity 10, when the sensor film layer 3 is pressed, a certain buffering effect can be achieved through the vacuum cavity 10, the sensor film layer 3 can withstand a relatively greater pressure, and the measurement range of the pressure sensor is also relatively large. The present utility model is also provided with an intermediate insulating isolation layer 2, a via hole layer 7, and an insulating encapsulation layer 9 to protect the sensor through the intermediate insulating isolation layer 2, the via hole layer 7, and the insulating encapsulation layer 9, making it more corrosion-resistant.

Claims

1. A MEMS absolute pressure sensor, comprising a substrate (1), characterized in that: It also includes an intermediate insulating isolation layer (2), a via layer (7), an insulating encapsulation layer (9), a sensor film layer (3) for sensing pressure, and a conductive material assembly (4) for connecting the sensor film layer (3); the substrate (1) is provided with a groove (5); the sensor film layer (3) is the base of the groove (5) and is supported by the intermediate insulating isolation layer (2); the sensor film layer (3) is connected between the substrate (1) and the intermediate insulating isolation layer (2); the sensor film layer (3) is provided with piezoresistive resistors (6), and the sensor film layer (3) is connected to the conductive material assembly (4) through the piezoresistive resistors (6); the intermediate insulating isolation layer (2) is connected to the via layer (7), and the via layer (7) is connected to the insulating encapsulation layer (9); the intermediate insulating isolation layer (2) is etched by photolithography to form an opening (8) for the sensor film layer (3); a vacuum chamber (10) communicating with the opening (8) is formed on the via layer (7); the vacuum chamber (10) is located between the sensor film layer (3) and the via layer (7).

2. The MEMS absolute pressure sensor according to claim 1, wherein: The size of the vacuum chamber (10) is larger than the size of the bottom of the groove (5).

3. The MEMS absolute pressure sensor according to claim 1, characterized in that: The substrate uses an SOI silicon substrate, and the thickness of the top silicon is 20 - 80 um.

4. The MEMS absolute pressure sensor according to claim 1, wherein: The length of the piezoresistive resistor (6) is 150 - 250 um, the width is 10 - 20 um, and the depth is 2 - 5 um.

5. A MEMS absolute pressure sensor according to claim 1, characterized in that: The sensor film layer (3) is square, with a side length of 600 - 900 um and a thickness of 20 - 80 um.

6. The MEMS absolute pressure sensor according to claim 1, wherein: The vacuum chamber (10) is formed by bonding the via layer (7) and the substrate (1).

7. A MEMS absolute pressure sensor according to claim 1, characterized in that: The intermediate insulating isolation layer (2) is composed of one or a combination of SiO2 or SiN thin films, with a thickness of 1 - 5 um.

8. A MEMS absolute pressure sensor according to claim 1, characterized in that: The insulating encapsulation layer (9) is filled with an organic epoxy organic substance.

9. The MEMS absolute pressure sensor according to claim 1, characterized in that: The via layer (7) uses a silicon material, with a thickness of 200 - 600 um, and the depth of the vacuum chamber (10) is 30 - 100 um.

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