MEMS pressure sensor chip and manufacturing method thereof

Abstract

The invention relates to the technical field of micro electro mechanical systems, in particular to an MEMS pressure sensor chip capable of working in an extreme environment and a manufacturing method of the MEMS pressure sensor chip. The pressure sensor comprises an SOI silicon-on-insulator substrate, a piezoresistive resistor, a middle silicon nitride insulation isolation layer, a through hole layer, an organic epoxy insulation packaging layer, a sensor film layer and a conductive material assembly used for connection. Four piezoresistive resistors are formed by ion implantation and are symmetrically distributed on the thin film layer to form a Wheatstone bridge structure. The sensor film layer is square, the size of the sensor film layer is smaller than that of the substrate, the sensor film layer is I-shaped, the thermal stress concentration effect is reduced, cracks or deformation is avoided, the sensor film layer and the substrate jointly form a vacuum cavity, and high structural stability is kept. The insulating packaging layer is connected with the through hole layer, and the through holes are connected with the insulating layer through the conductive material of the opening of the insulating layer. The sensor provided by the invention can keep higher measurement precision and sensitivity in an extreme temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-electromechanical systems (MEMS), and in particular to a MEMS pressure sensor chip that can be used in extreme environments and a manufacturing method thereof. Background Art

[0002] Pressure sensors are widely used in the automotive, medical and aerospace fields. Their basic principle is to convert the pressure change or deformation change into an electrical signal. Among them, MEMS pressure sensors are mainly piezoresistive and capacitive. The current mainstream MEMS pressure sensor is based on the principle of piezoresistance, that is, piezoresistive pressure sensor, which is widely used in automotive systems to test key parameters such as airbag pressure, fuel pressure, engine oil pressure, and intake pipe pressure.

[0003] In view of the improvement of MEMS sensor technology, existing patent documents have given methods to improve the sensitivity and measurement range of MEMS pressure sensors. For example, the MEMS pressure sensor disclosed in patent document CN107144378A has a core principle that the film is deformed by pressure, causing the inductance value of the inductor coil located above the film to change. The inductance value of the inductor coil is measured by a fixed capacitor and an LC loop composed of an inductor coil, thereby obtaining the corresponding pressure value. This method can effectively convert the pressure signal into an electrical signal, realize accurate pressure measurement, and improve the measurement accuracy to a certain extent. However, there are still problems and defects such as limited measurement range, low sensitivity, and easy corrosion, which limit its wider application. In addition, some existing sensors are not sensitive enough to subtle pressure changes, which affects the measurement accuracy. In some harsh environments, such as high humidity or environments containing corrosive substances, the sensor is also easily damaged. With the development of science and technology, the market demand for MEMS is expanding, and it is imperative to solve the current problems.

[0004] Therefore, the present invention designs and provides a novel structure and manufacturing method of a MEMS absolute pressure sensor, which realizes accurate, sensitive and stable pressure measurement through special process treatment. Summary of the invention

[0005] The purpose of the present invention is to provide a new type of MEMS absolute pressure sensor with optimized structure and enhanced performance, as well as a method for manufacturing the sensor, to solve the problems existing in the prior art. Through material selection, new materials with excellent mechanical properties and corrosion resistance are used to ensure that the sensor can work stably and long-term under extreme conditions. Combined with the fine design of the inductor coil and film structure, the sensitivity and dynamic response range of the sensor are enhanced. Then, advanced packaging processes and technologies are used to improve the reliability and service life of the product. A set of efficient micromachining processes are developed to ensure consistency and cost-effectiveness during mass production.

[0006] To achieve the above-mentioned purpose, the present invention proposes the following technical solution: a MEMS pressure sensor chip and a manufacturing method, characterized in that the pressure sensor includes an SOI silicon substrate, four piezoresistive resistors on the top silicon, a SiO2 or SiN insulating isolation layer, a Ti or TiN barrier layer, a metal tungsten contact layer, an organic epoxy insulating packaging layer, and a conductive connecting through hole.

[0007] With respect to claim 1, the present invention adopts an SOI silicon substrate, a piezoresistive resistor design of a specific size, and a special process for the insulating isolation layer and the metal contact layer. The four piezoresistive resistors on the top silicon form a Wheatstone bridge structure, and accurate pressure measurement is achieved through components such as an intermediate silicon nitride insulating isolation layer, a through-hole layer, and an organic epoxy insulating packaging layer, thereby improving the stability and reliability of the sensor under extreme conditions.

[0008] In accordance with claim 2, the sensor thin film layer is provided with a metal contact layer that connects the piezoresistive resistor to form a Wheatstone bridge. The metal contact layer is usually made of a highly conductive metal material such as tungsten or aluminum. The metal contact layer is used to connect the piezoresistive resistor to an external circuit to ensure that the signal can be effectively transmitted to the subsequent signal processing circuit. The metal contact layer is deposited on the sensor thin film layer and patterned by photolithography and etching techniques to form the required metal wiring.

[0009] Preferably, with respect to claim 3, the SOI (silicon on insulator) silicon substrate is a special semiconductor material structure in which a thin layer of single-crystal silicon (top silicon) is located on a layer of insulator (usually silicon dioxide SiO2), and the insulating layer is located on a thicker silicon substrate. The structure has many advantages in MEMS and integrated circuits, especially in the manufacture of high-performance pressure sensors.

[0010] Furthermore, especially when the thickness of the top silicon is 20-80um, it has electrical isolation. Since there is an insulator between the top silicon and the substrate, the parasitic capacitance and resistance can be effectively reduced, the electrical performance of the circuit can be improved, the signal interference can be reduced, and the signal-to-noise ratio of the sensor can be improved.

[0011] The silicon substrate has thermal stability, and the presence of the insulating layer reduces heat conduction, thereby reducing the impact of temperature on device performance. The top silicon layer is relatively thin (20-80um), but still provides sufficient mechanical strength to support the deformation of the sensor diaphragm. The appropriate thickness ensures that the diaphragm can produce detectable deformation when subjected to pressure, and will not break due to being too thin. In addition, the SOI silicon substrate is compatible with standard CMOS processes, which is convenient for large-scale production and integration.

[0012] According to claim 4, four piezoresistive resistors are formed on the sensor thin film layer by ion implantation or the like. The four piezoresistive resistors are symmetrically distributed on the thin film layer to form a Wheatstone bridge structure. Furthermore, the four piezoresistive resistors are formed by ion implantation, which can accurately control the formation position and resistance value of the resistors.

[0013] Furthermore, the dimensions of the piezoresistive resistor are 150-250 um in length, 10-20 um in width, and 2-5 um in depth. The dimensions are designed to ensure that the piezoresistive resistor has sufficient sensitivity and reliability to produce a detectable resistance change when the sensor film layer is subjected to pressure.

[0014] Preferably, with respect to claim 5, the sensor membrane layer is smaller than the substrate and has an I-shaped structure. The I-shaped structure, i.e., wider in the center and narrower at both ends, can evenly disperse stress distribution when the sensor membrane is subjected to external mechanical stress, reduce the thermal stress concentration effect, and avoid local deformation or cracks caused by stress concentration at a certain point. This allows the sensor to maintain high mechanical strength and stability under high temperature and high pressure environments.

[0015] The vacuum cavity is formed by bonding the through-hole isolation layer to the substrate, so that the sensor can maintain high structural stability under high pressure and vacuum environment. By bonding the through-hole isolation layer to the substrate, a closed vacuum environment is formed to ensure the reliability and accuracy of the sensor under extreme conditions.

[0016] The intermediate insulating layer is made of one or more combinations of silicon dioxide (SiO2) or silicon nitride (SiN) films, with a thickness of 1-5um. Further, the intermediate insulating layer is used to protect the sensor film layer and provide necessary electrical isolation. Furthermore, the use of high-quality SiO2 or SiN films can effectively reduce parasitic capacitance and resistance and improve the electrical performance of the circuit. Appropriate thickness ensures good insulation performance and mechanical strength.

[0017] Preferably, with respect to claim 8, the insulating encapsulation layer is filled with organic epoxy. The insulating encapsulation layer is used to protect the entire sensor structure and prevent the sensor from being affected by the external environment.

[0018] Furthermore, organic epoxy materials have good insulation properties, corrosion resistance and mechanical strength, and can effectively shield electromagnetic interference and protect the internal structure, ensuring that the pressure sensor chip in special environments will not be deformed due to the fragility of the support frame and oxidation.

[0019] The through hole isolation layer is made of silicon material with a thickness of 200-600um, and the through hole isolation layer groove depth is 30-100um. Further, the through hole isolation layer is made of silicon material, which has good mechanical strength and processing performance. The thickness of the through hole isolation layer is 200-600um, ensuring sufficient mechanical support and structural stability. The through hole isolation layer groove depth is 30-100um, providing sufficient space to form a vacuum cavity.

[0020] Preferably, the wear resistance and hardness of the support frame are effectively increased, and the support frame has a certain toughness to the high temperature and high pressure environment during application, ensuring that the pressure sensor chip in a special environment will not fail due to the fragility of the support frame.

[0021] The output voltage of the Wheatstone bridge will also change as the resistance of the piezoresistive resistor changes. The voltage change reflects the pressure on the sensor film layer. Furthermore, the voltage change is usually small and needs to be amplified by an amplifier circuit for subsequent processing and reading. The output voltage change is amplified by an amplifier circuit to increase the amplitude of the signal, making it easier to detect and process.

[0022] Furthermore, the amplified signal passes through a filtering circuit to remove high-frequency noise and other interfering signals to ensure the purity of the signal. The filtered analog signal is converted into a digital signal through an analog-to-digital converter (ADC), which converts the continuous analog signal into a discrete digital signal for subsequent digital processing.

[0023] Furthermore, the processed digital signal is converted to a corresponding pressure value through a preset algorithm or calibration curve. This process usually involves comparing and calibrating the digital signal with a known pressure standard to obtain an accurate pressure reading.

[0024] The manufacturing steps of the pressure sensor are a total of fourteen steps, among which step one is to select the first substrate through graphics, and use ion implantation to implant boron ions into the front of the top silicon to form four piezoresistive resistors on the top silicon. Step two, use CVD to form a SIO2 or SIN film to protect the device layer and form an insulating isolation layer. Step three, expose the piezoresistive resistors of the lower device layer connected to the insulating layer by etching. Step four, form Ti and TiN barrier layers by PVD or CVD, and then anneal at high temperature to form an ohmic contact. Step five, form a layer of metal tungsten by CVD, grind off the metal tungsten on the surface by mechanical grinding, leave tungsten columns at the opening position of the insulating isolation layer, and form a metal contact layer of the sensor film layer. Step six, pattern the substrate silicon of the through hole and the sensor film layer substrate, and form two grooves of the vacuum cavity by etching, with a depth of 30-100um.

[0025] Furthermore, in step seven, the sensor membrane substrate and the through-hole substrate are bonded to form an integral silicon wafer. Step eight, the first substrate is ground to 300-500um by grinding, and the second substrate is ground to 300-500um by grinding, and the through-hole layer is formed. Step nine, a layer of S102 film with a thickness of 1-3um is formed on the surface of the first substrate by CVD method, and the supporting protective layer is formed, and it can also be used as a hard mask layer to complete the etching of the back opening groove. Step ten, a hole is opened in the through-hole isolation layer by photolithography and etching process, and the metal contact layer position of the sensor membrane layer involved in step five is opened. Step eleven, a metal conductive material is formed at the through-hole by PVD, CVD or electroplating to form a metal connection. After patterning, the excess part is etched away to form a metal contact point.

[0026] Furthermore, in step 12, after filling the through hole with organic epoxy or other insulating material, it is leveled to form an insulating encapsulation layer. In step 13, the metal contact points connected by opening the through hole in the insulating encapsulation layer are connected by photolithography and etching processes, and metal contacts are formed by PVD or electroplating processes. In step 14, the first substrate is patterned, and the hard mask layer described in step 9 is etched into a pattern, and then a substrate groove is etched by a dry etching process until the sensor film layer stops.

[0027] The above technical solution can achieve the following beneficial effects: Compared with the prior art, the present invention has the following advantages and positive effects: (1) The pressure sensor provided by the present invention adopts an SOI silicon substrate and integrates four piezoresistive resistors in the top silicon to form a Wheatstone bridge structure. Since the SOI structure has good electrical isolation and thermal stability, it can effectively eliminate parasitic effects and temperature drift, thereby significantly improving the measurement accuracy and sensitivity of the sensor in extreme temperature environments.

[0028] (2) The present invention designs a vacuum cavity between the sensor film layer and the through-hole layer and adopts a multi-layer film packaging process, so that the sensor can maintain a high structural stability under high pressure and vacuum environment, thereby avoiding failure of traditional sensors due to film fatigue or deformation in severe pressure fluctuations.

[0029] (3) The present invention adopts a combination of a Ti / TiN barrier layer and a metal tungsten column contact layer in the design, and realizes metal interconnection with low contact resistance and high conductivity by optimizing the ohmic contact interface. In addition, the introduction of the insulating packaging layer can effectively shield external electromagnetic interference and improve the signal transmission stability of the overall device.

[0030] (4) The sensor membrane layer of the present invention adopts an I-shaped structure design, which can evenly disperse the stress distribution when the sensor membrane is subjected to external mechanical stress, reduce the thermal stress concentration effect, and thus avoid the phenomenon that traditional rectangular or circular membrane layers are prone to cracks or deformation under pressure.

[0031] (5) The present invention provides a structural model of a pressure sensor, which can effectively increase the wear resistance and hardness of the support frame, and has a certain toughness in the high temperature and high pressure environment during the application process, ensuring that the pressure sensor chip in a special environment will not be deformed due to the fragility and oxidation of the support frame, thereby causing the chip function to fail. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0033] Figure 1 It is a schematic diagram of the structural model of the MEMS pressure sensor provided by the present invention.

[0034] Figure 2 It is a flow chart of the working principle of the MEMS pressure sensor provided by the present invention.

[0035] Figure 3 It is a process flow chart of steps 1 to 4 in the pressure sensor manufacturing method adopted by the present invention.

[0036] Figure 4 It is a process flow chart of steps 7 to 8 in the pressure sensor manufacturing method adopted by the present invention.

[0037] Figure 5 It is a process flow chart of steps 9 to 10 in the pressure sensor manufacturing method adopted by the present invention.

[0038] Figure 6 It is a process flow chart of steps ten to eleven in the pressure sensor manufacturing method adopted by the present invention.

[0039] Figure 7 It is a process flow chart of steps twelfth to fourteenth in the pressure sensor manufacturing method adopted by the present invention.

[0040] In the figure: (1) SOI silicon substrate, (2) sensor membrane layer, (3) piezoresistance, (4) SiO2 insulating isolation layer, (5) through-hole substrate, (6) electrical contact metal tungsten column, (7) membrane layer conductive material component, (8) intermediate silicon nitride insulating isolation layer, and (9) organic epoxy insulating packaging layer. DETAILED DESCRIPTION

[0041] The present invention is further explained below with reference to the accompanying drawings and specific embodiments.

[0042] The embodiments of the present invention relate to a MEMS pressure sensor chip and a manufacturing method thereof. Figure 1 As shown, the MEMS pressure sensor structure includes the following components: a silicon-on-insulator (SOI) substrate, a piezoresistive resistor, an intermediate silicon nitride insulating isolation layer, a through-hole layer, an organic epoxy insulating packaging layer, a sensor membrane layer, and a conductive material component for connection.

[0043] like Figure 2 As shown, the working principle of the MEMS pressure sensor includes key steps such as the formation of the Wheatstone bridge structure, the change of the piezoresistive resistance, signal amplification and processing, and finally converts the pressure into an electrical signal. The process is that the external pressure is sensed to the sensor, and the pressure causes the sensor diaphragm to deform. The deformation of the diaphragm transmits the stress to the piezoresistive element. Further, the piezoresistive element changes its resistance value due to the stress. The change in resistance is converted into a voltage signal through the Wheatstone bridge circuit. Further, the signal is amplified and filtered, the voltage signal is amplified, and unnecessary noise is filtered out. Perform a signal range check, if it is within the normal working range, proceed to the next step; if the signal exceeds the normal working range, trigger an alarm or perform a calibration procedure, and then return to step 6. Convert the processed analog voltage signal into a digital signal. The digital signal is further processed to display the pressure value.

[0044] like Figure 3 As shown, in step 1, boron ions are implanted into the front side of the top silicon by pattern selection on the first substrate using ion implantation to form four piezoresistive resistors. Four piezoresistive resistors are formed on the sensor thin film layer by ion implantation and the like. The four piezoresistive resistors are symmetrically distributed on the thin film layer to form a Wheatstone bridge structure. When the sensor thin film layer is deformed by external pressure, the resistance value of the piezoresistive resistor will change. The length of the piezoresistive resistor is 150-250um, the width is 10-20um, and the depth is 2-5um.

[0045] Step 2 uses chemical vapor deposition (CVD) to form a SiO2 or SiN film to protect the device layer and form an insulating isolation layer. CVD deposition forms a layer of SiO2 or SiN film, which not only protects the piezoresistive resistor, but also provides electrical isolation, reduces parasitic capacitance and resistance, and improves the electrical performance of the circuit.

[0046] Step 3: The piezoresistance resistor of the device layer connected to the ground by etching is exposed. The etching process needs to be precisely controlled to ensure that the piezoresistance resistor is completely exposed and not damaged. Step 4: Form Ti and TiN barrier layers by physical vapor deposition (PVD) or chemical vapor deposition (CVD), and then perform high temperature annealing to form ohmic contacts to ensure good electrical contact performance.

[0047] Furthermore, in step 5, a layer of metal tungsten is formed by CVD, and the metal tungsten on the surface is ground off by mechanical grinding, leaving tungsten columns at the opening positions of the insulating isolation layer to form a metal contact layer of the sensor film layer. In step 6, the substrate silicon of the through hole and the sensor film layer substrate are patterned, and two grooves of the vacuum cavity are formed by etching, with a depth of 30-100um. The sensor film layer is provided with a metal contact layer connected to a Wheatstone bridge by a piezoresistive resistor.

[0048] The metal contact layer is used to connect the piezoresistive resistor to the external circuit to ensure that the signal can be effectively transmitted to the subsequent signal processing circuit. The metal contact layer is deposited on the sensor film layer and patterned by photolithography and etching technology to form the required metal connection.

[0049] like Figure 4 As shown, step seven uses bonding to form the sensor film substrate and the through-hole substrate into an integral silicon wafer. Prepare the sensor film substrate and the through-hole substrate. Structures such as piezoresistive resistors, insulating isolation layers, and metal contact layers have been formed on the sensor film substrate. The through-hole substrate is used to form a vacuum cavity and a through-hole. Bonding technology, including but not limited to anodic bonding and direct bonding, is used to tightly bond the sensor film substrate and the through-hole substrate together. During the bonding process, it is necessary to ensure that the interface between the two substrates is clean and flat to achieve a good bonding effect. After bonding, the two substrates form an integral silicon wafer, laying the foundation for the subsequent formation of the vacuum cavity and through-hole.

[0050] Furthermore, in step eight, the first substrate is ground to 300-500um by grinding, and the second substrate is ground to 300-500um by grinding to form a through-hole layer. The second substrate (through-hole substrate) is also ground to a thickness of 300-500um by mechanical grinding or chemical mechanical polishing (CMP). The thickness of the substrate after grinding is moderate, which is convenient for subsequent processing and treatment.

[0051] like Figure 5 As shown, in step nine, a SiO2 film layer with a thickness of 1-3 um is formed on the surface of the first substrate by a CVD method to form a support protection layer, which can also be used as a hard mask layer to complete the back opening groove etching. A SiO2 film layer is deposited on the surface of the first substrate, i.e., the sensor film layer substrate, by a chemical vapor deposition method.

[0052] Furthermore, the SiO2 film layer plays a supporting and protective role, preventing damage to the sensor film layer during subsequent processing. The film layer can also be used as a hard mask layer for subsequent back opening groove etching. The hard mask layer can provide higher etching selectivity and better protection effect, ensuring the accuracy and controllability of the etching process.

[0053] Step 10: Open holes in the through-hole isolation layer by photolithography and etching process to open up the metal contact layer position of the sensor film layer involved in step 5.

[0054] Furthermore, the etching process includes but is not limited to dry etching and wet etching techniques, and etching is performed on the through-hole isolation layer to open up the position connected to the metal contact layer of the sensor membrane layer formed in step 5. After the etching is completed, the opening on the through-hole isolation layer exposes the metal contact layer of the sensor membrane layer, providing a channel for subsequent metal filling and connection.

[0055] Furthermore, Figure 6 As shown, in step 10, a hole is opened in the through-hole isolation layer by a photolithography process to open the metal contact layer position of the sensor film layer involved in step 5. The through-hole isolation layer is made of silicon material, which has good mechanical strength and processing performance. The thickness of the through-hole isolation layer is 200-600um, ensuring sufficient mechanical support and structural stability. The depth of the through-hole isolation layer groove is 30-100um, providing enough space to form a vacuum cavity.

[0056] Preferably, the wear resistance and hardness of the support frame are effectively increased, and the support frame has a certain toughness to the high temperature and high pressure environment during application, ensuring that the pressure sensor chip in a special environment will not fail due to the fragility of the support frame.

[0057] Step 11: Form a metal conductive material at the through hole by PVD, CVD or electroplating to form a metal connection. After patterning, the excess part is etched away to form a metal contact point.

[0058] like Figure 7 As shown, further, in step 12, after the through hole is filled with organic epoxy or other insulating material, it is leveled to ensure the flatness of the entire chip surface. This not only improves the overall aesthetics of the chip, but also provides a level foundation for subsequent processes to form an insulating packaging layer.

[0059] The insulating packaging layer is filled with organic epoxy organic matter. The insulating packaging layer is used to protect the entire sensor structure and prevent the external environment from affecting the sensor.

[0060] Furthermore, organic epoxy materials have good insulation properties, corrosion resistance and mechanical strength, and can effectively shield electromagnetic interference and protect the internal structure, ensuring that the pressure sensor chip in special environments will not be deformed due to the fragility of the support frame and oxidation.

[0061] Step 13: Use photolithography and etching processes to open the metal contact points of the insulating packaging layer through the through hole, and use PVD or electroplating processes to form metal contact connections. Through these metal connections, the metal contact points in the through hole are connected to the external circuit to ensure effective signal transmission. Step 14: The first substrate is patterned, and the hard mask layer described in step 9 is etched into a pattern, and then a substrate groove is etched using a dry etching process until the sensor film layer stops. The present invention provides a high-precision, high-reliability MEMS pressure sensor and a manufacturing method thereof, which ensures the performance of the sensor in various applications.

[0062] The above-mentioned configuration can also be set in other embodiments, and the scope of protection of the present invention includes but is not limited to the situations listed in this embodiment. Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, so the scope of protection of the present invention shall be subject to the scope defined by the claims.

[0063] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. The present invention provides a MEMS pressure sensor chip and a manufacturing method. The MEMS pressure sensor is composed of a silicon substrate on an SOI insulator, four piezoresistive resistors on the top silicon, an intermediate silicon nitride insulating isolation layer, a through-hole layer, an organic epoxy insulating packaging layer, a sensor membrane layer for sensing pressure, and a conductive material component for connection.

2. The sensor film layer transmits the signal through multiple metal interconnections; the substrate is provided with a groove, the base of the groove is the sensor film layer, and the base at the other end of the groove is supported by an insulating oxide layer; the intermediate insulating isolation layer is photoetched to form an opening with the sensor film layer, and a metal conductive material is used to lead out the metal contact layer; the through-hole layer is provided with through holes respectively connected to the Wheatstone bridge on the metal contact layer, the through holes are filled with conductive materials, and the through holes connect the metal contact layer of the sensor film and the metal connection end of the packaging layer; The insulating packaging layer is connected to the through-hole layer, and the through-holes are connected to the insulating layer through the conductive material opened in the insulating layer; a vacuum cavity is provided in the pressure sensor, one end of the vacuum cavity is the sensor film layer, and the vacuum cavity is larger than the bottom size of the substrate groove.

3. The pressure sensor according to claim 1, characterized in that: The sensor film layer is provided with a metal contact layer which is connected by piezoresistors to form a Wheatstone bridge.

4. The MEMS pressure sensor according to claim 1, characterized in that The SO1 silicon substrate is a special semiconductor material structure, in which a thin layer of single crystal silicon is located on a layer of insulator, and the insulating layer is located on a thicker silicon substrate, and the thickness of the top silicon is 20-80um.

5. There is an insulator between the top silicon and the substrate to reduce parasitic capacitance and resistance, improve the electrical performance of the circuit, reduce signal interference, and improve the signal-to-noise ratio of the sensor. At the same time, it has thermal stability. The presence of the insulating layer reduces heat conduction and reduces the impact of temperature on device performance. The top silicon layer is relatively thin, but it can still provide sufficient mechanical strength to support the deformation of the sensor diaphragm. Ensure that the diaphragm can produce detectable deformation when under pressure and will not break due to being too thin. The SOI silicon substrate is compatible with standard CMOS processes.

6. The MEMS pressure sensor according to claim 2, characterized in that: Four piezoresistive resistors are formed on the sensor film layer by ion implantation or other methods. The four piezoresistive resistors are symmetrically distributed on the film layer to form a Wheatstone bridge structure. When the sensor film layer is deformed by external pressure, the resistance value of the piezoresistive resistor will change. The length of the piezoresistive resistor is 150-250um, the width is 10-20um, and the depth is 2-5um.

7. The MEMS pressure sensor according to claim 2, characterized in that: The pressure sensor film layer is square, with a side length of 600-900um and a thickness of 20-80um. The size of the sensor film layer is smaller than that of the substrate and is in an I-shape, which can evenly disperse stress and reduce the thermal stress concentration effect.

8. The pressure sensor according to claim 1, characterized in that: The vacuum chamber of the pressure sensor is formed by bonding the through-hole isolation layer to the substrate.

9. The MEMS pressure sensor according to claim 1, characterized in that: The intermediate insulating layer is made of one or more combinations of silicon dioxide or silicon nitride films, with a thickness of 1-5 um.

10. The MEMS pressure sensor according to claim 1, characterized in that: The insulating packaging layer is filled with organic epoxy organic matter.

11. The MEMS pressure sensor according to claim 1, characterized in that: The through hole isolation layer is made of silicon material with a thickness of 200-600um, and a groove depth of 30-100um.

12. The MEMS pressure sensor according to claim 4, characterized in that: The output voltage of the Wheatstone bridge changes, and the signal that can be further amplified is filtered, analog-to-digital converted, noise is removed and converted into a digital signal, and finally converted into a corresponding pressure value.

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