A MEMS piezoresistive differential pressure sensor

Abstract

The application provides a MEMS piezoresistive differential pressure sensor, comprising a silicon substrate, a first glass, a second glass, a first fishbone unit, a second fishbone unit and a pressure-sensitive resistor; the silicon substrate has an anchoring area and a sensitive area; the first glass is fixed to the anchoring area on the first side of the silicon substrate; the second glass is fixed to the anchoring area on the second side of the silicon substrate; four first fishbone units are arranged at intervals on four side walls in the first regular octagonal groove; four second fishbone units are arranged at intervals on four side walls in the second regular octagonal groove; the first fishbone unit and the second fishbone unit each comprise a plurality of groups of fishbone subunits connected in sequence; each group of fishbone subunits comprises a pressure-sensitive area, a connecting area and a supporting area. One technical effect of the application is to improve the sensitivity and precision of the MEMS piezoresistive differential pressure sensor, and the reliability and a large range of the MEMS piezoresistive differential pressure sensor under high sensitivity design are also considered.

Description

Technical Field

[0001] This invention belongs to the field of differential pressure sensor technology, specifically relating to a MEMS piezoresistive differential pressure sensor. Background Technology

[0002] MEMS (Micro-Electro-Mechanical System) piezoresistive differential pressure sensors utilize the piezoresistive effect of semiconductor materials. By interconnecting piezoresistors to form a Wheatstone bridge, they convert ambient pressure into an electrical signal, thereby achieving pressure measurement. Compared to capacitive and piezoelectric differential pressure sensors, MEMS piezoresistive differential pressure sensors offer superior linearity and reliability, and are therefore widely used in aerospace, industrial control, and medical electronics.

[0003] Currently, most common MEMS piezoresistive differential pressure sensors use square-shaped sensitive films, with piezoresistors distributed on the film surface. High sensitivity is typically achieved by increasing the area and decreasing the thickness of the sensitive film. However, this design approach reduces the sensor's usable measurement range, lifespan, and reliability, while offering only limited sensitivity improvement. Furthermore, issues related to manufacturing processes, packaging, uneven temperature distribution, and impurities introduced during use can lead to suboptimal stress distribution on the sensitive film, resulting in poor actual detection accuracy.

[0004] In addition, temperature affects the zero-point drift of MEMS piezoresistive differential pressure sensors, leading to a decrease in measurement accuracy. Typically, additional stress is generated during the packaging process of MEMS piezoresistive differential pressure chips, causing zero-point drift of the sensor and affecting the batch calibration of products. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art and provide a new technical solution for MEMS piezoresistive differential pressure sensor.

[0006] According to one aspect of the present invention, a MEMS piezoresistive differential pressure sensor is provided, comprising:

[0007] A silicon substrate having an anchoring region and a sensitive region, wherein the anchoring region is arranged around the outside of the sensitive region; a first regular octagonal groove is provided on the sensitive region on a first side of the silicon substrate, and a second regular octagonal groove is provided on the sensitive region on a second side of the silicon substrate corresponding to the first regular octagonal groove.

[0008] A first glass and a second glass, wherein the first glass is fixed to an anchoring area on a first side of the silicon substrate and forms a first cavity with a sensitive area on the first side of the silicon substrate, and a first through hole is provided on the first glass at a position corresponding to the center of the first regular octagonal groove; the second glass is fixed to an anchoring area on a second side of the silicon substrate and forms a second cavity with a sensitive area on the second side of the silicon substrate, and a second through hole is provided on the second glass at a position corresponding to the center of the second regular octagonal groove.

[0009] First fishbone unit and second fishbone unit: four first fishbone units are spaced apart on the four side walls of the first regular octagonal groove and extend from the bottom of the first regular octagonal groove toward the center of the first regular octagonal groove; four second fishbone units are spaced apart on the four side walls of the second regular octagonal groove and extend from the bottom of the second regular octagonal groove toward the center of the second regular octagonal groove; and the first fishbone units and the second fishbone units are staggered.

[0010] The varistor comprises multiple sets of sequentially connected fishbone sub-units in both the first and second fishbone units. Each set of fishbone sub-units includes a varistor region, a connecting region, and a supporting region. One side of the connecting region is connected to the varistor region, and the other side is connected to the supporting region. Adjacent fishbone sub-units are connected to the varistor region of another fishbone unit through the supporting region of one fishbone sub-unit. The fishbone units located at the ends are connected to the sidewall of the first or second regular octagonal groove through the varistor region. Each varistor region is provided with a varistor.

[0011] Optionally, the adjacent side walls of the first regular octagonal groove and the second regular octagonal groove are transitioned by rounded corners.

[0012] Optionally, the projection of the pressure-sensitive area onto the bottom of the first or second regular octagonal groove is rectangular.

[0013] Optionally, the silicon substrate is made of monocrystalline silicon with a thickness of 200-1000 μm.

[0014] Optionally, the projection of the connecting area onto the bottom of the first regular octagonal groove or the bottom of the second regular octagonal groove is a rectangle or multiple spaced rectangles.

[0015] Optionally, the length of the connection area is less than the length of the pressure-sensitive area.

[0016] Optionally, the projection of the support area onto the bottom of the first or second regular octagonal groove is an isosceles trapezoid, and the upper and lower bases of the isosceles trapezoid are parallel to one side wall of the first or second regular octagonal groove, respectively; the angle between the waist and lower base of the isosceles trapezoid is half the interior angle of the first or second regular octagonal groove.

[0017] The lower base of a plurality of isosceles trapezoids in the first or second fishbone unit gradually decreases along the direction from near the anchorage area to away from the anchorage area.

[0018] Optionally, the thickness of both the first and second fishbone units is 10-100 μm.

[0019] Optionally, both the first through hole and the second through hole are circular holes.

[0020] One technical advantage of this invention is that:

[0021] In this embodiment, the MEMS piezoresistive differential pressure sensor utilizes a designed octagonal sensitive film, combined with four first fishbone units and four second fishbone units to form a wave-like layout design, thereby achieving stress concentration in the pressure-sensitive area. In addition, taking advantage of the characteristics of the fishbone's multiple appendages, multiple sets of Wheatstone bridges are designed for amplification, and combined with the Wheatstone bridges on both sides of the sensitive area for two-stage differential amplification, thereby improving the sensitivity of the MEMS piezoresistive differential pressure sensor.

[0022] Moreover, the MEMS piezoresistive differential pressure sensor employs a design with four first fishbone units and four second fishbone units. The appendage bones are evenly and widely distributed, which serves as a reinforcing rib and greatly enhances the strength of the sensitive area. This design balances the reliability and range of the MEMS piezoresistive differential pressure sensor under high sensitivity.

[0023] Furthermore, the MEMS piezoresistive differential pressure sensor employs a design with four first fishbone units and four second fishbone units. The appendage bones are evenly and widely distributed, allowing for the acquisition of more and more accurate stress data. This can mitigate the impact of non-ideal thin-film stress distribution in the sensitive area caused by processing technology, packaging, uneven temperature, and impurities during use, thereby improving the accuracy of actual detection.

[0024] In addition, the MEMS piezoresistive differential pressure sensor forms two Wheatstone bridge outputs above and below the pressure-sensitive region, which improves the sensitivity of the MEMS piezoresistive differential pressure sensor. Furthermore, through the differential amplification circuit, it achieves self-compensation for the additional zero-point drift caused by temperature stress and packaging stress, which is beneficial to improving the accuracy of subsequent batch calibration and conditioning of the sensor. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of a MEMS piezoresistive differential pressure sensor according to an embodiment of the present invention;

[0026] Figure 2 This is a top view of a MEMS piezoresistive differential pressure sensor according to an embodiment of the present invention;

[0027] Figure 3 This is a bottom view of a MEMS piezoresistive differential pressure sensor according to an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the fishbone subunit of the first fishbone unit of a MEMS piezoresistive differential pressure sensor according to an embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram of the fishbone subunit of the second fishbone unit of a MEMS piezoresistive differential pressure sensor according to an embodiment of the present invention.

[0030] Figure 6 This is a cross-sectional schematic diagram of a MEMS piezoresistive differential pressure sensor according to an embodiment of the present invention.

[0031] In the figure: 1. Silicon substrate; 11. Anchoring area; 12. Sensitive area; 21. First fishbone unit; 22. Second fishbone unit; 201. Pressure-sensitive area; 202. Connection area; 203. Support area; 31. First glass; 32. Second glass; 41. First through hole; 42. Second through hole. Detailed Implementation

[0032] Various exemplary embodiments of this application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this application.

[0033] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0034] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0035] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0036] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0037] According to a first aspect of the present invention, a MEMS piezoresistive differential pressure sensor is provided, which can solve the problem that the sensitivity, range, and reliability of existing MEMS piezoresistive differential pressure sensors cannot be simultaneously balanced. Furthermore, it reduces the zero-point drift of MEMS piezoresistive differential pressure sensors caused by temperature and packaging stress, and mitigates the accuracy degradation caused by non-ideal stress distribution of the sensitive thin film during processing, temperature non-uniformity, packaging, and use, thereby improving the accuracy and reliability of MEMS piezoresistive differential pressure sensors.

[0038] See Figure 1 and Figure 6 The first direction is defined as the X-axis, the second direction as the Y-axis, and the third direction as the Z-axis. The X-axis, Y-axis, and Z-axis are perpendicular to each other.

[0039] Specifically, see Figures 1 to 6 The MEMS piezoresistive differential pressure sensor includes:

[0040] A silicon substrate 1 has an anchoring region 11 and a sensitive region 12, with the anchoring region 11 surrounding the outside of the sensitive region 12. The sensitive region 12 on the first side of the silicon substrate 1 is provided with a first regular octagonal groove, and the sensitive region 12 on the second side of the silicon substrate 1 is provided with a second regular octagonal groove corresponding to the first regular octagonal groove. It should be noted that the bottom of the first or second regular octagonal groove is the bottom surface, and the sidewall is the side surface.

[0041] A first glass 31 and a second glass 32 are provided. The first glass 31 is fixed to the anchoring area 11 on the first side of the silicon substrate 1 and forms a first cavity with the sensitive area 12 on the first side of the silicon substrate 1. A first through hole 41 is provided on the first glass 31 at a position corresponding to the center of the first regular octagonal groove. The second glass 32 is fixed to the anchoring area 11 on the second side of the silicon substrate 1 and forms a second cavity with the sensitive area 12 on the second side of the silicon substrate 1. A second through hole 42 is provided on the second glass 32 at a position corresponding to the center of the second regular octagonal groove. The first through hole 41 communicates with the first cavity, and the second through hole 42 communicates with the second cavity.

[0042] First fishbone units 21 and second fishbone units 22: Four first fishbone units 21 are spaced apart and disposed on the four sidewalls of the first regular octagonal groove, extending towards the center of the first regular octagonal groove from the bottom of the groove, i.e., the side of each of the four first fishbone units 21 facing the bottom of the first regular octagonal groove is fixedly connected to the bottom of the first regular octagonal groove; four second fishbone units 22 are spaced apart and disposed on the four sidewalls of the second regular octagonal groove, extending towards the center of the first regular octagonal groove from the bottom of the groove. The bottom of the groove extends towards the center of the second regular octagonal groove, that is, the side of the four second fishbone units 22 facing the bottom of the second regular octagonal groove is fixedly connected to the bottom of the second regular octagonal groove; and the first fishbone units 21 and the second fishbone units 22 are staggered; wherein, each first fishbone unit 21 corresponds to a fishbone area on the first side of the silicon substrate 1, and each second fishbone unit 22 corresponds to a fishbone area on the second side of the silicon substrate 1, and the four first fishbone units 21 and the four second fishbone units 22 together constitute eight fishbone areas;

[0043] The varistor, the first fishbone unit 21 and the second fishbone unit 22, each include multiple sets of fishbone sub-units connected in sequence; each set of fishbone sub-units includes a varistor region 201, a connecting region 202 and a supporting region 203, and one side of the connecting region 202 is connected to the varistor region 201, and the other side is connected to the supporting region 203; adjacent fishbone sub-units are connected to the varistor region 201 of another fishbone sub-unit through the supporting region 203 of one fishbone sub-unit, and the fishbone sub-units located at the ends are connected to the sidewall of the first regular octagonal groove or the sidewall of the second regular octagonal groove through the varistor region; wherein, each varistor region 201 is provided with a varistor. The main purpose of the supporting region 203 is to reduce the stress in the non-varistor region and improve the actual strength of the sensitive region 12.

[0044] It should be noted that the working principle of the MEMS piezoresistive differential pressure sensor of the present invention is as follows:

[0045] Firstly, in practical application environments, different pressure media contact the silicon substrate 1 through the first through hole 41 and the second through hole 42, causing deformation of the sensitive area 12 and generating corresponding stress. Tensile stress or tension stress is generated in eight fishbone areas, namely the four first fishbone units 21 and the four second fishbone units 22, causing the corresponding sensitive resistor on the pressure-sensitive area 201 to generate a corresponding resistance change, and the current pressure difference or pressure is characterized by electrical output.

[0046] Secondly, in practical applications, MEMS differential pressure sensors typically have a small measurement range, thus requiring high sensitivity. In this embodiment, multiple sets of pressure-sensitive regions 201 exist on the fishbone region of each side of the sensitive region 12, forming a corresponding number of Wheatstone bridges, which greatly improves the sensitivity of the MEMS piezoresistive differential pressure sensor. Simultaneously, the Wheatstone bridges on the first and second sides of the sensitive region 12 form a second-stage differential amplifier circuit, multiplying the sensitivity of the MEMS piezoresistive differential pressure sensor. Furthermore, the fishbone-shaped structure design composed of the pressure-sensitive region 201, the connecting region 202, and the supporting region 203 in this embodiment achieves better thin-film stress concentration, further enhancing the sensitivity of the MEMS differential pressure sensor.

[0047] Thirdly, the special structural design of the eight fishbone areas, using the pressure-sensitive area 201 and the connecting area 202 as the appendages of the fishbone, acts like reinforcing ribs. While ensuring the sensitivity of the MEMS differential pressure sensor, it also considers the strength of the sensitive area 12 itself, improving the reliability and actual measurement range of the MEMS differential pressure sensor. Simultaneously, the pressure-sensitive area 201 is more widely and uniformly distributed, which on the one hand improves the sensitivity of the MEMS differential pressure sensor, and on the other hand acquires more accurate pressure values, weakening the influence of processing technology, temperature, packaging, and usage on the sensitive area 12, and reducing measurement errors.

[0048] Fourthly, in this embodiment, eight fishbone regions are evenly and alternately distributed on opposite sides of the sensitive area 12 (i.e., the first side and the second side), each corresponding to one side of a regular octagon. This wavy distribution reduces stress concentration at the edges of the fishbone region, increases stress at the pressure-sensitive area 201 to improve sensitivity, and reduces stress at weak points to improve device reliability. Simultaneously, this design achieves a more precise stress distribution in the sensitive area 12. Through the differential output of the Wheatstone bridge on the first and second sides of the sensitive area 12, the additional zero drift caused by temperature and stress in the MEMS piezoresistive differential pressure sensor can be reduced, improving sensor accuracy. Furthermore, the differential output of the Wheatstone bridge on the first and second sides of the sensitive area 12 reduces output drift and nonlinearity caused by thermal stress, achieving self-compensation for temperature drift.

[0049] In this embodiment, the MEMS piezoresistive differential pressure sensor utilizes a designed octagonal sensitive film, combined with four first fishbone units 21 and four second fishbone units 22 to form a wave-like layout design, thereby achieving stress concentration in the pressure-sensitive area 201. In addition, taking advantage of the characteristics of the fishbone's multiple appendages, multiple sets of Wheatstone bridges are designed for amplification, and combined with the Wheatstone bridges on both sides of the sensitive area 12 for two-stage differential amplification, thereby improving the sensitivity of the MEMS piezoresistive differential pressure sensor.

[0050] Moreover, the MEMS piezoresistive differential pressure sensor employs a design with four first fishbone units 21 and four second fishbone units 22. The appendage bones are evenly and widely distributed, which serves as a reinforcing rib and greatly enhances the strength of the sensitive area 12. This design balances the reliability and range of the MEMS piezoresistive differential pressure sensor under high sensitivity design.

[0051] Furthermore, the MEMS piezoresistive differential pressure sensor employs a design with four first fishbone units 21 and four second fishbone units 22. The appendage bones are evenly and widely distributed, allowing for the acquisition of more and more accurate stress data. This can mitigate the impact of non-ideal thin-film stress distribution in the sensitive area 12 caused by processing technology, packaging, uneven temperature, and impurities during use, thereby improving the accuracy of actual detection.

[0052] In addition, the MEMS piezoresistive differential pressure sensor forms two Wheatstone bridge outputs above and below the pressure-sensitive region 201, which improves the sensitivity of the MEMS piezoresistive differential pressure sensor. Furthermore, through the differential amplification circuit, it achieves self-compensation for the additional zero-point drift caused by temperature stress and packaging stress, which is beneficial to improving the accuracy of subsequent batch calibration and conditioning of the sensor.

[0053] In one specific embodiment, the silicon substrate 1 is made of monocrystalline silicon and has a thickness of 200-1000 μm. The anchoring region 11 has the same thickness as the silicon substrate 1, and the sensitive region 12 has a thickness of 10-100 μm.

[0054] For example, the projection shape of the sensitive area 12 along a third direction is a regular octagon.

[0055] In this embodiment, eight fishbone regions are staggered on one side of the octagon on both sides of the sensitive area 12. This arrangement ensures that the projection of the sensitive area 12 onto a cylindrical cross-section parallel to a third direction results in an undulating wave shape. This allows for a smaller thickness design while maintaining the strength of the sensitive area 12, thus improving the sensitivity of the MEMS piezoresistive differential pressure sensor. Furthermore, the staggered distribution of the eight fishbone regions on one side of the octagon of the sensitive area 12, and their even distribution on both sides of the sensitive area 12, forms a wave-like up-and-down distribution structure. Compared to arranging fishbone regions on both sides of the same location on the sensitive area 12, this arrangement has the advantage of a smaller and gentler thickness difference between the fishbone regions and the sensitive area 12. Stress is less likely to concentrate at the boundary between the fishbone regions and the sensitive area 12, thereby improving the sensitivity of the MEMS piezoresistive differential pressure sensor and enhancing the reliability of the device.

[0056] In addition, the eight fishbone areas are staggered on one side of the octagon of the sensitive area 12 and are evenly distributed on both sides of the sensitive area 12, forming a wave-like upper and lower distribution structure. The purpose is to collect the stress at different positions on the sensitive area 12 more evenly, so as to reduce the additional effects of uneven load, thereby better realizing the zero-point drift compensation of the MEMS piezoresistive differential pressure sensor.

[0057] Optionally, the adjacent side walls of the first regular octagonal groove and the second regular octagonal groove are transitioned by rounded corners.

[0058] In the above embodiment, the sensitive area 12 adopts an optimized rounded octagonal groove structure, which has a better stress concentration effect than the traditional rectangular film, and can reduce the stress concentration in the area where the non-sensitive film is located, increase the sensitivity of the MEMS piezoresistive differential pressure sensor, and improve its reliability.

[0059] For example, the first glass 31 is located above the silicon substrate 1 along a third direction, and the second glass 32 is located below the silicon substrate 1 along a third direction. Both the first glass 31 and the second glass 32 are made of 7740 glass and have a thickness of 500 μm. In other embodiments, other glass types and thicknesses may be used as needed.

[0060] Furthermore, the first glass 31 and the second glass 32 serve to protect the silicon substrate 1, ensuring the normal operation of the MEMS piezoresistive differential pressure sensor; and simultaneously reducing drift errors caused by direct contact between impurities and the sensitive area 12 during packaging or use. Additionally, the symmetrical distribution of the first glass 31 and the second glass 32 allows for significantly reduced thermal and packaging stress on the zero bias of the MEMS piezoresistive differential pressure sensor through differential output.

[0061] For example, both the first fishbone unit 21 and the second fishbone unit 22 have six sets of fishbone sub-units. In other embodiments, other distribution groups can be designed according to actual conditions.

[0062] Optionally, the projection of the pressure-sensitive area 201 onto the bottom of the first or second regular octagonal groove is rectangular. This projection onto the bottom of the first or second regular octagonal groove is also the projection along a third direction. For example, the projection of the pressure-sensitive area 201 along the third direction is a rectangle of 200μm * 20μm.

[0063] In one embodiment, the purpose of the varistor region 201 is for subsequent processing of the varistor. The specific size of the varistor region 201 is consistent with the actual size of the varistor. Through structural self-limiting, the accuracy of the length and width of the actual processed varistor is ensured, thereby improving the processing accuracy of the resistance and piezoresistive coefficient of the processed varistor and ensuring the actual accuracy of the MEMS piezoresistive differential pressure sensor.

[0064] Optionally, the projection of the connecting area 202 onto the bottom of the first regular octagonal groove or the bottom of the second regular octagonal groove is a rectangle or multiple spaced rectangles.

[0065] In the above embodiment, the connection area 202 is a rectangular block, and the connection strength between the connection area 202 and the pressure-sensitive area 201 can also be increased by increasing the number of rectangular blocks. For example, multiple connection areas 202 are distributed in an array.

[0066] Optionally, the length of the connection region 202 is less than the length of the varistor region 201. This helps to more accurately position the varistor region 201 during the fabrication of the varistor, thereby ensuring the dimensional accuracy of the varistor.

[0067] Optionally, the projection of the support area 203 onto the bottom of the first regular octagonal groove or the bottom of the second regular octagonal groove is an isosceles trapezoid, and the upper and lower bases of the isosceles trapezoid are parallel to one side wall of the first regular octagonal groove or one side wall of the second regular octagonal groove, respectively; the angle between the waist side and the lower base of the isosceles trapezoid is half of the interior angle of the first regular octagonal groove or the interior angle of the second regular octagonal groove;

[0068] The lower base of a plurality of isosceles trapezoids in the first fishbone unit 21 or the second fishbone unit 22 gradually decreases in the direction from near the anchoring area 11 to away from the anchoring area 11.

[0069] In the above embodiments, the multiple support areas 203 of the same fishbone sub-unit are similar but not identical, and the size of the support area 203 closer to the center of the sensitive area 12 is smaller, so as to ensure that each fishbone area (i.e. the first fishbone unit 21 and the second fishbone unit 22) is located only in one-eighth of the area of ​​the sensitive area 12, thereby better ensuring the accuracy and sensitivity of the differential pressure sensor.

[0070] Optionally, the thickness of both the first fishbone unit 21 and the second fishbone unit 22 is 10-100 μm. This helps to improve the sensitivity of the sensitive area 12.

[0071] Optionally, both the first through hole 41 and the second through hole 42 are circular holes. This helps to reduce concentrated stress during glass processing and improve the strength of the first glass 31 and the second glass 32.

[0072] In other embodiments, one of the first through hole 41 and the second through hole 42 may be left unprocessed to serve as an absolute pressure sensor.

[0073] In this embodiment, the first through-hole 41 is located at the center of the first glass 31, exposing the sensitive area 12. The second through-hole 42 is located at the center of the second glass 32, exposing the sensitive area 12.

[0074] For example, the diameters of the first through hole 41 and the second through hole 42 are both 100-2000 μm. In other embodiments, other through hole sizes and shapes may be used as needed.

[0075] In one embodiment, the thicknesses of the first fishbone unit 21 and the second fishbone unit 22 are 10-100 μm, respectively.

[0076] For example, there is a height difference between the eight fishbone regions and the sensitive region 12, which aims to increase local stress and improve the sensitivity of the MEMS piezoresistive differential pressure sensor. In addition, subsequent processes such as doping, thin film deposition, and etching are completed based on the thicker eight fishbone regions. Compared with processing directly on the sensitive region 12, this avoids damage to the sensitive film caused by subsequent processing processes and ensures the accuracy of processing.

[0077] In this embodiment, each fishbone subunit is sequentially grouped from the pressure-sensitive area 201, the connecting area 202, and the supporting area 203. Its overall projection along a third direction resembles a fishbone, with the pressure-sensitive area 201 and the connecting area 202 representing the appendages of the fishbone. The more groups of pressure-sensitive areas 201, connecting areas 202, and supporting areas 203 are arrayed, the more appendages the fishbone contains, the more Wheatstone bridges are formed, resulting in a higher actual output and higher sensitivity for the MEMS piezoresistive differential pressure sensor. Furthermore, the more appendages the fishbone contains, the more robust the actual fish body, meaning a higher strength in the sensitive area 12, ensuring the reliability of the MEMS piezoresistive differential pressure sensor and improving its actual range. This solves the incompatibility issues of traditional piezoresistive pressure sensors in terms of sensitivity, strength, and range. Moreover, the varistor 201 has a wider distribution than traditional varistors, which can obtain a more uniform and accurate stress distribution at each point of the sensitive area 12. This not only reduces the accuracy error caused by process errors such as uneven thickness of the sensitive area 12, but also eliminates the accuracy error caused by impurities in the sensitive area 12 during packaging or use. It also helps to reduce the accuracy error caused by uneven temperature distribution in the sensitive area 12 leading to uneven local stress. Compared with the distribution of traditional varistors, it has more accurate pressure detection.

[0078] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A MEMS piezoresistive differential pressure sensor, characterized in that, include: A silicon substrate having an anchoring region and a sensitive region, wherein the anchoring region is arranged around the outside of the sensitive region; a first regular octagonal groove is provided on the sensitive region on a first side of the silicon substrate, and a second regular octagonal groove is provided on the sensitive region on a second side of the silicon substrate corresponding to the first regular octagonal groove. A first glass and a second glass, wherein the first glass is fixed to an anchoring area on a first side of the silicon substrate and forms a first cavity with a sensitive area on the first side of the silicon substrate, and a first through hole is provided on the first glass at a position corresponding to the center of the first regular octagonal groove; the second glass is fixed to an anchoring area on a second side of the silicon substrate and forms a second cavity with a sensitive area on the second side of the silicon substrate, and a second through hole is provided on the second glass at a position corresponding to the center of the second regular octagonal groove. First fishbone unit and second fishbone unit, four first fishbone units are spaced apart and disposed on the four side walls of the first regular octagonal groove; four second fishbone units are spaced apart and disposed on the four side walls of the second regular octagonal groove; and the first fishbone units and the second fishbone units are staggered. The varistor comprises multiple sets of sequentially connected fishbone sub-units in both the first and second fishbone units. Each set of fishbone sub-units includes a varistor region, a connecting region, and a supporting region. One side of the connecting region is connected to the varistor region, and the other side is connected to the supporting region. Adjacent fishbone sub-units are connected to the varistor region of another fishbone unit through the supporting region of one fishbone sub-unit. The fishbone units located at the ends are connected to the sidewall of the first or second regular octagonal groove through the varistor region. Each varistor region is provided with a varistor.

2. The MEMS piezoresistive differential pressure sensor according to claim 1, characterized in that, The adjacent side walls of the first regular octagonal groove and the second regular octagonal groove are transitioned by rounded corners.

3. The MEMS piezoresistive differential pressure sensor according to claim 1, characterized in that, The projection of the pressure-sensitive area onto the bottom of the first or second regular octagonal groove is rectangular.

4. The MEMS piezoresistive differential pressure sensor according to claim 1, characterized in that, The silicon substrate is made of single-crystal silicon and has a thickness of 200-1000μm.

5. The MEMS piezoresistive differential pressure sensor according to claim 1, characterized in that, The projection of the connecting area onto the bottom of the first regular octagonal groove or the bottom of the second regular octagonal groove is a rectangle or multiple rectangles spaced apart.

6. The MEMS piezoresistive differential pressure sensor according to claim 1, characterized in that, The length of the connection area is less than the length of the pressure-sensitive area.

7. The MEMS piezoresistive differential pressure sensor according to claim 1, characterized in that, The projection of the support area onto the bottom of the first or second regular octagonal groove is an isosceles trapezoid, and the upper and lower bases of the isosceles trapezoid are parallel to one side wall of the first or second regular octagonal groove, respectively; the angle between the waist and lower base of the isosceles trapezoid is half the interior angle of the first or second regular octagonal groove. The lower base of a plurality of isosceles trapezoids in the first or second fishbone unit gradually decreases along the direction from near the anchorage area to away from the anchorage area.

8. The MEMS piezoresistive differential pressure sensor according to claim 1, characterized in that, The thickness of both the first and second fishbone units is 10-100 μm.

9. The MEMS piezoresistive differential pressure sensor according to claim 1, characterized in that, Both the first through hole and the second through hole are circular holes.

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