A sensitive structure of differential pressure sensor

Abstract

The present invention relates to the technical field of pressure sensors, and provides a differential pressure sensor sensitive structure, which includes an ASIC conditioning chip, an upper substrate, a lower substrate and a pressure-sensitive film, wherein the upper substrate and the lower substrate are arranged oppositely and at intervals, the ASIC conditioning chip is arranged on the side of the upper substrate away from the lower substrate, the pressure-sensitive film is arranged between the upper substrate and the lower substrate, the upper substrate, the pressure-sensitive film and the lower substrate are bonded, a first chamber is formed between the upper substrate and the pressure-sensitive film, and a second chamber is formed between the pressure-sensitive film and the lower substrate; an upper capacitor Ct is formed between the lower electrode of the upper substrate in the first chamber and the first electrode of the pressure-sensitive film; a lower capacitor Cb is formed between the upper electrode of the lower substrate in the second chamber and the second electrode of the pressure-sensitive film; wherein an isolation groove is provided on the pressure-sensitive film. The present application can effectively isolate packaging stress and temperature stress, thereby suppressing mechanical common mode errors and improving the consistency of sensitive structures.

Description

Technical Field

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

[0002] As a high-precision MEMS pressure sensor, quartz pressure sensor has the advantages of small size, low power consumption, high precision and small temperature drift coefficient.

[0003] The quartz capacitance differential pressure sensor is based on the differential capacitance principle. The quartz base film is used as the pressure sensing element. The two sides of the quartz base film sense the two-way pressure input from the outside world. When the two-way pressure changes, the pressure sensing film is strained, which causes the differential capacitance formed by the pressure sensing film and the upper and lower electrodes to change, thereby realizing pressure measurement. The quartz capacitance differential pressure meter head is integrated with the ASIC conditioning chip at the chip level, directly outputs digital signals, is compatible with high-speed digital circuits, and can effectively suppress common mode errors. In view of the urgent need for high-precision differential pressure sensors in the field of high-precision atmospheric data systems and industrial flow control, a quartz capacitance pressure sensor based on the differential capacitance principle is proposed. Compared with metal capacitors, ceramic capacitors and silicon capacitors, it has the advantages of small size and high integration. By designing the pressure sensitive structure of the differential capacitance structure, high-precision differential pressure measurement is realized. The differential capacitance gap is accurately controlled by the anchor point limit boss, thereby realizing accurate control of the nominal capacitance. It has the advantages of low power consumption and strong anti-interference ability, and has become the development trend of high-precision differential pressure sensors in the future. The quartz capacitance differential pressure sensor has a range of +-1kPa~+-50MPa, and a comprehensive accuracy of 0.075%FS at full temperature, which can measure gas and liquid pressure.

[0004] The existing metal pressure-sensitive membrane and ceramic pressure-sensitive membrane use laser welding or eutectic welding process to achieve three-layer structure sealing, which cannot solve the problems of thermal expansion coefficient matching and thermal stress removal, and can easily lead to a relatively large temperature drift coefficient in the full temperature range. Summary of the invention

[0005] The present invention provides a differential pressure sensor sensitive structure, which is used to solve the defect that when the three-layer structure is sealed by laser welding or eutectic welding process in the prior art, the thermal expansion coefficient matching and thermal stress cannot be effectively removed, which easily leads to a relatively large temperature drift coefficient in the whole temperature range. The packaging stress and temperature stress can be effectively isolated, thereby suppressing the mechanical common mode error and improving the consistency of the sensitive structure.

[0006] The present invention provides a differential pressure sensor sensitive structure, comprising an ASIC conditioning chip, an upper substrate, a lower substrate and a pressure-sensitive film, wherein the upper substrate and the lower substrate are arranged opposite to each other and spaced apart, the ASIC conditioning chip is arranged on a side of the upper substrate away from the lower substrate, the pressure-sensitive film is arranged between the upper substrate and the lower substrate, the upper substrate, the pressure-sensitive film and the lower substrate are bonded and connected, a first chamber is formed between the upper substrate and the pressure-sensitive film, and a second chamber is formed between the pressure-sensitive film and the lower substrate; an upper capacitor Ct is formed between a lower electrode of the upper substrate located in the first chamber and a first electrode of the pressure-sensitive film; a lower capacitor Cb is formed between an upper electrode of the lower substrate located in the second chamber and a second electrode of the pressure-sensitive film; wherein an isolation groove is provided on the pressure-sensitive film.

[0007] According to a differential pressure sensor sensitive structure provided by the present invention, the pressure-sensitive membrane is provided with a first isolation groove and a second isolation groove which are symmetrical along its midline plane, the first isolation groove is provided on the side of the pressure-sensitive membrane facing the upper substrate and is located in the first chamber; the second isolation groove is provided on the side of the pressure-sensitive membrane facing the lower substrate and is located in the second chamber.

[0008] According to a differential pressure sensor sensitive structure provided by the present invention, the first isolation groove and the second isolation groove are arranged in a ring shape, the first isolation groove is arranged at intervals on the outer peripheral side of the first electrode, and the second isolation groove is arranged at intervals on the outer peripheral side of the two electrodes.

[0009] According to a differential pressure sensor sensitive structure provided by the present invention, the angle between the side wall of the first isolation groove or the second isolation groove and the horizontal plane is α, wherein 52°≤α≤90°.

[0010] According to a differential pressure sensor sensitive structure provided by the present invention, the upper substrate, the pressure-sensitive film and the lower substrate are bonded and connected by glass paste.

[0011] According to a differential pressure sensor sensitive structure provided by the present invention, the glass paste includes an upper glass paste layer and a lower glass paste layer, an upper material ring is provided on the side of the upper substrate facing the pressure-sensitive membrane, and the upper glass paste layer is arranged around the upper material ring to bond the upper substrate and the pressure-sensitive membrane; a lower material ring is provided on the side of the lower substrate facing the pressure-sensitive membrane, and the lower glass paste layer is arranged around the lower material ring to bond the lower substrate and the pressure-sensitive membrane.

[0012] According to a differential pressure sensor sensitive structure provided by the present invention, the outer peripheral edge of the upper substrate facing the pressure-sensitive film is protruded with a plurality of upper limit bosses, and the plurality of upper limit bosses are evenly arranged along the peripheral side of the pressure-sensitive film; And / or, a plurality of lower limit bosses are protruding from an outer peripheral edge of the lower substrate on one side facing the pressure-sensitive film, and the plurality of lower limit bosses are evenly arranged along the peripheral side of the pressure-sensitive film.

[0013] According to a differential pressure sensor sensitive structure provided by the present invention, the upper substrate is provided with an upper air guide hole penetrating the upper substrate along the thickness direction, and the upper air guide hole is connected to the first chamber; and / or, The lower substrate is provided with a lower air guide hole penetrating the lower substrate along the thickness direction, and the lower air guide hole is communicated with the second chamber.

[0014] According to a differential pressure sensor sensitive structure provided by the present invention, a first electrode pad is arranged on the side of the pressure-sensitive film facing the upper substrate, and the first electrode pad is electrically connected to the first electrode; a second electrode pad is arranged on the side of the pressure-sensitive film facing the lower substrate, and the second electrode pad is electrically connected to the second electrode; the first electrode pad and the second electrode pad are electrically connected through the side edges of the coating.

[0015] According to a differential pressure sensor sensitive structure provided by the present invention, the differential pressure sensor sensitive structure further comprises bonding gold wires, and the ASIC conditioning chip is electrically connected to the first electrode, the second electrode, the upper electrode and the lower electrode respectively through the bonding gold wires.

[0016] The sensitive structure of the differential pressure sensor provided by the present invention has an isolation groove on the pressure-sensitive membrane. The isolation groove can form a stress isolation beam on the pressure-sensitive membrane to effectively isolate the packaging stress and temperature stress, thereby suppressing the mechanical common mode error; at the same time, compared with the pressure-sensitive membrane design of the flat membrane structure, the pressure-sensitive membrane with the isolation groove in the present application can transform the pressure deformation input from the outside from tensile and compressive deformation into bending deformation, thereby improving the sensitivity of the pressure-sensitive membrane; and through the bending deformation with lower rigidity, the assembly stress and thermal stress can be transformed into the deformation of the concave cavity folded beam, thereby ensuring the zero-bias stability of the vibration beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is an assembly cross-sectional view of the sensitive structure of the differential pressure sensor provided by the present invention.

[0019] Figure 2 yes Figure 1 Schematic diagram of the structure of the middle and lower basement.

[0020] Figure 3 yes Figure 2 Cross-sectional view of the middle and lower basement.

[0021] Figure 4 yes Figure 1 Schematic diagram of the structure of the medium pressure-sensitive membrane.

[0022] Figure 5 yes Figure 4 Cross-sectional view of the medium pressure-sensitive membrane.

[0023] Figure 6 yes Figure 1 Schematic diagram of the structure of the middle and upper base.

[0024] Figure 7 yes Figure 6 Cross-sectional view of the middle and upper base.

[0025] Figure 8 yes Figure 6 Top view of the middle and upper basement.

[0026] Reference numerals: 10. Sensitive structure of differential pressure sensor; 100. ASIC conditioning chip; 200, upper substrate; 210, feeding ring; 220, upper limit boss; 230, upper air guide hole; 240, upper electrode; 250, gold wire bonding window; 260, upper electrode pad; 300, first chamber; 310, upper capacitor Ct; 400, pressure-sensitive film; 410, first isolation groove; 420, second isolation groove; 430, first electrode pad; 440, second electrode pad; 450, coating side edge; 460, first electrode; 470, second electrode; 480, gold wire bonding window; 500, second chamber; 510, lower capacitor Cb; 600, lower substrate; 610, blanking ring; 620, lower limit boss; 630, lower air guide hole; 640, lower electrode; 650, lower electrode pad; 700, applying a glass slurry layer; 800, lower glass slurry layer; 900, Bonding gold wire. DETAILED DESCRIPTION

[0027] The following embodiments of the present invention are described in further detail in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0028] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0029] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0030] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0031] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0032] Combine the following Figures 1 to 8 , the sensitive structure of the differential pressure sensor provided by the embodiment of the present invention is described in detail through specific embodiments and their application scenarios.

[0033] The differential pressure sensor sensitive structure 10 provided by the present invention is described below. Figures 1 to 7 The differential pressure sensor sensitive structure 10 includes an ASIC conditioning chip 100, an upper substrate 200, a lower substrate 600 and a pressure-sensitive film 400. The upper substrate 200 and the lower substrate 600 are arranged opposite to each other and spaced apart. The ASIC conditioning chip 100 is arranged on a side of the upper substrate 200 away from the lower substrate 600. The pressure-sensitive film 400 is arranged between the upper substrate 200 and the lower substrate 600. The upper substrate 200, the pressure-sensitive film 400 and the lower substrate 600 are bonded and connected. 00, and a second chamber 500 is formed between the pressure-sensitive film 400 and the lower substrate 600; an upper capacitor Ct310 is formed between the lower electrode 640 of the upper substrate 200 located in the first chamber 300 and the first electrode 460 of the pressure-sensitive film 400; a lower capacitor Cb510 is formed between the upper electrode 240 of the lower substrate 600 located in the second chamber 500 and the second electrode 470 of the pressure-sensitive film 400; wherein an isolation groove is opened on the pressure-sensitive film 400.

[0034] The ASIC (Application-Specific Integrated Circuit) conditioning chip is located on the side of the upper substrate 200 away from the lower substrate 600, and is responsible for processing and outputting differential capacitance signals. It calculates the differential capacitance value by detecting the changes in the upper capacitance Ct310 and the lower capacitance Cb510, thereby realizing pressure measurement. The ASIC conditioning chip 100 can convert analog signals into digital signals, is compatible with high-speed digital circuits, and facilitates subsequent data processing and transmission.

[0035] The upper substrate 200 is opposite to the lower substrate 600 and is spaced apart. A lower electrode 640 is provided on the upper substrate 200. The main function of the upper substrate 200 is to provide a supporting platform for mounting the ASIC conditioning chip 100 and forming the first chamber 300. An upper capacitor Ct310 is formed between the lower electrode 640 of the upper substrate 200 and the first electrode 460 of the pressure-sensitive film 400 for detecting pressure changes.

[0036] The lower substrate 600 is opposite to the upper substrate 200 and is spaced apart. An upper electrode 240 is disposed on the lower substrate 600. The main function of the lower substrate 600 is to provide another supporting platform for forming the second chamber 500. A lower capacitor Cb510 is formed between the upper electrode 240 of the lower substrate 600 and the second electrode 470 of the pressure-sensitive film 400 for detecting pressure changes.

[0037] The pressure-sensitive film 400 is disposed between the upper substrate 200 and the lower substrate 600 and is a core component that is sensitive to pressure. The pressure-sensitive film 400 is provided with a first electrode 460 and a second electrode 470, which respectively form an upper capacitor Ct310 and a lower capacitor Cb510 with the lower electrode 640 of the upper substrate 200 and the upper electrode 240 of the lower substrate 600. When the external pressure changes, the pressure-sensitive film 400 will deform, causing the capacitance values ​​of the upper capacitor Ct310 and the lower capacitor Cb510 to change, thereby achieving pressure measurement.

[0038] The upper substrate 200, the pressure-sensitive film 400 and the lower substrate 600 are bonded together to form an integral structure. The bonding connection ensures the stability and airtightness of the structure and prevents the external environment from affecting the internal chamber. The glass paste sealing that matches the thermal expansion coefficient of the quartz crystal improves the bonding strength, airtightness and electrical insulation of the components.

[0039] The first chamber 300 is located between the upper substrate 200 and the pressure-sensitive film 400. The upper capacitor Ct310 is formed between the lower electrode 640 of the upper substrate 200 and the first electrode 460 of the pressure-sensitive film 400. The pressure change in the first chamber 300 causes the pressure-sensitive film 400 to deform, thereby changing the value of the upper capacitor Ct310.

[0040] The second chamber 500 is located between the pressure-sensitive film 400 and the lower substrate 600. A lower capacitor Cb510 is formed between the upper electrode 240 of the lower substrate 600 and the second electrode 470 of the pressure-sensitive film 400. Pressure changes in the second chamber 500 cause deformation of the pressure-sensitive film 400, thereby changing the value of the lower capacitor Cb510.

[0041] The isolation grooves opened on the pressure-sensitive film 400 form stress isolation beams, which can effectively isolate packaging stress and temperature stress, reduce the influence of these stresses on the deformation of the pressure-sensitive film 400, thereby suppressing mechanical common mode errors and improving the stability and accuracy of the sensor.

[0042] Compared with the flat membrane structure of the pressure-sensitive membrane 400, the pressure-sensitive membrane 400 with the isolation groove can change the external pressure deformation from tensile and compressive deformation to bending deformation. The bending deformation has a lower stiffness, so the sensitivity of the pressure-sensitive membrane 400 is significantly improved, and it can more accurately reflect the changes in external pressure.

[0043] Through the bending deformation with lower stiffness, the assembly stress and thermal stress can be converted into the deformation of the concave cavity folded beam, which ensures the zero bias stability of the vibration beam and improves the zero bias stability of the sensor under different temperatures and assembly conditions.

[0044] The present invention provides an isolation groove on the pressure-sensitive membrane 400. The isolation groove can form a stress isolation beam on the pressure-sensitive membrane 400 to effectively isolate the packaging stress and temperature stress, thereby suppressing the mechanical common mode error. At the same time, compared with the design of the pressure-sensitive membrane 400 with a flat membrane structure, the pressure-sensitive membrane 400 with an isolation groove in the present application can transform the pressure deformation input from the outside from tensile and compressive deformation into bending deformation, thereby improving the sensitivity of the pressure-sensitive membrane 400. Moreover, through the bending deformation with lower stiffness, the assembly stress and thermal stress can be transformed into the deformation of the concave cavity folded beam, thereby ensuring the zero-bias stability of the vibration beam.

[0045] Reference Figure 1 According to a differential pressure sensor sensitive structure 10 provided by the present invention, the pressure-sensitive membrane 400 is provided with a first isolation groove 410 and a second isolation groove 420 which are symmetrical along its midline plane, the first isolation groove 410 is provided on the side of the pressure-sensitive membrane 400 facing the upper substrate 200, and is located in the first chamber 300; the second isolation groove 420 is provided on the side of the pressure-sensitive membrane 400 facing the lower substrate 600, and is located in the second chamber 500.

[0046] It is understandable that the first isolation groove 410 and the second isolation groove 420 form a stress isolation beam on the pressure-sensitive film 400. The isolation beam can effectively isolate the packaging stress and temperature stress, and reduce the influence of these stresses on the deformation of the pressure-sensitive film 400. During the packaging process, packaging stress may be generated due to the different thermal expansion coefficients of different materials. The design of the isolation groove can disperse these stresses to avoid adverse effects on the pressure-sensitive film 400. When the temperature changes, different materials have different degrees of thermal expansion, which may generate temperature stress. The design of the isolation groove can effectively absorb and disperse these temperature stresses and reduce their influence on the pressure-sensitive film 400.

[0047] The first isolation groove 410 and the second isolation groove 420 are symmetrically arranged along the midline plane of the pressure-sensitive film 400. This symmetrical design ensures that the deformation of the pressure-sensitive film 400 when under pressure is symmetrical, reducing the error caused by asymmetrical deformation. In addition, the symmetrical design helps to suppress mechanical common mode errors and improve the stability and accuracy of the sensor. At the same time, the symmetrical design makes the response of the pressure-sensitive film 400 in different directions more uniform, improving the reliability and consistency of the sensor.

[0048] Reference Figure 1 According to a differential pressure sensor sensitive structure 10 provided by the present invention, the first isolation groove 410 and the second isolation groove 420 are arranged in a ring shape, the first isolation groove 410 is arranged at intervals on the outer peripheral side of the first electrode 460, and the second isolation groove 420 is arranged at intervals on the outer peripheral side of the two electrodes.

[0049] It is understandable that the design of the annular isolation groove enables the pressure-sensitive film 400 to more effectively isolate and disperse the stress to the edge area of ​​the pressure-sensitive film 400 when it is subjected to external pressure. This not only reduces the direct impact of stress on the capacitance measurement area, but also improves the fatigue resistance of the pressure-sensitive film 400. Through the stress isolation and dispersion effect of the annular isolation groove, the stability and durability of the sensor are significantly improved. Even under long-term high-load working conditions, the sensor can maintain accurate measurement results.

[0050] The annular isolation groove separates the outer peripheral side of the first electrode 460 and the second electrode 470 from other areas of the pressure-sensitive film 400, forming a relatively independent capacitance measurement area, reducing the interference of the external environment on the capacitance measurement area, and improving the accuracy of the measurement. By protecting the capacitance measurement area, the sensor can respond more accurately to changes in external pressure and output more stable and reliable measurement results.

[0051] Reference Figure 5 According to a differential pressure sensor sensitive structure 10 provided by the present invention, the angle between the side wall of the first isolation groove 410 or the second isolation groove 420 and the horizontal plane is α, wherein 52°≤α≤90°.

[0052] It is understandable that the angle α between the sidewall of the isolation groove and the horizontal plane directly affects the distribution and transmission of stress on the pressure-sensitive film 400. When α is in the range of 52° to 90°, the isolation groove can better disperse the stress to the edge area of ​​the pressure-sensitive film 400, while reducing the direct impact of stress on the capacitance measurement area. By optimizing the angle α, the stress dispersion and isolation effect of the isolation groove is significantly improved, thereby improving the stability and measurement accuracy of the sensor.

[0053] Optionally, the angle α between the side wall of the first isolation groove 410 or the second isolation groove 420 and the horizontal plane can be 52°, 53°, 54°, 55°, 56°, 57°, 58°, 59°, 60°, 61°, 62°, 63°, 64°, 65°, 66°, 67°, 68°, 69°, 70°, 71°, 72°, 73°, 74°, 75°, 76°, 77°, 78°, 79°, 80°, 81°, 82°, 83°, 84°, 85°, 86°, 87°, 88°, 89° or 90°, and the specific angle can be selected according to specific needs and is not particularly limited here.

[0054] Reference Figure 1 According to a differential pressure sensor sensitive structure 10 provided by the present invention, the upper substrate 200, the pressure-sensitive film 400 and the lower substrate 600 are bonded and connected by glass paste.

[0055] It is understandable that the present embodiment realizes the bonding connection of the upper substrate 200, the pressure-sensitive film 400 and the lower substrate 600 through glass paste. After curing, the glass paste can form a hard and dense connection layer, which tightly combines the upper substrate 200, the pressure-sensitive film 400 and the lower substrate 600. It can effectively prevent the external environment (such as moisture, dust, etc.) from interfering with the inside of the sensor, and ensure the stability and reliability of the sensor in high-precision measurement. Through the bonding connection of the glass paste, a high-precision sealed chamber is formed inside the sensor, providing a stable environment for capacitance measurement. The thermal expansion coefficient of the glass paste after curing is similar to that of materials such as quartz, so that the sensor can maintain the stability of the internal structure when the temperature changes. In this way, the glass paste sealing that matches the thermal expansion coefficient of the quartz crystal is used to improve the bonding strength, air tightness, and electrical insulation of the parts, the wafer-level alignment sintering is used to improve the packaging efficiency, and the alignment assembly vibration beam is used to improve the assembly accuracy.

[0056] Reference Figure 2 and Figure 6 According to a differential pressure sensor sensitive structure 10 provided by the present invention, the glass paste includes an upper glass paste layer 700 and a lower glass paste layer 800, an upper material ring 210 is provided on the side of the upper substrate 200 facing the pressure-sensitive film 400, and the upper glass paste layer 700 is arranged around the upper material ring 210 to bond the upper substrate 200 and the pressure-sensitive film 400; a lower material ring 610 is provided on the side of the lower substrate 600 facing the pressure-sensitive film 400, and the lower glass paste layer 800 is arranged around the lower material ring 610 to bond the lower substrate 600 and the pressure-sensitive film 400.

[0057] It is understandable that, in this embodiment, by respectively providing an upper glass paste layer 700 and a lower glass paste layer 800 on the upper substrate 200 and the lower substrate 600, it is possible to ensure a more uniform bonding connection between the pressure-sensitive film 400 and the upper and lower substrates 600. Uniform bonding connection helps to reduce stress concentration and deformation caused by uneven connection, thereby improving the stability and measurement accuracy of the sensor.

[0058] The opening of the upper material ring 210 and the lower material ring 610 enables the glass paste to be more accurately positioned in the connection area between the pressure-sensitive film 400 and the upper and lower substrates 600. This not only helps to reduce the waste of paste, but also ensures that the connection area is fully filled, thereby enhancing the sealing effect and preventing the external environment from interfering with the inside of the sensor.

[0059] The double-layer glass paste design enables the sensor to better maintain the stability of its internal structure when the temperature changes. At the same time, since the connection layer formed after the glass paste solidifies has high strength and toughness, it can enhance the structural strength of the sensor and enable it to withstand greater external pressure and vibration.

[0060] Reference Figure 2 , Figure 3 , Figure 6 and Figure 7 According to a differential pressure sensor sensitive structure 10 provided by the present invention, the upper substrate 200 is provided with a plurality of upper limit bosses 220 protruding from the outer peripheral edge of one side of the pressure-sensitive membrane 400, and the plurality of upper limit bosses 220 are evenly arranged along the peripheral side of the pressure-sensitive membrane 400; the lower substrate 600 is provided with a plurality of lower limit bosses 620 protruding from the outer peripheral edge of one side of the pressure-sensitive membrane 400, and the plurality of lower limit bosses 620 are evenly arranged along the peripheral side of the pressure-sensitive membrane 400.

[0061] It is understandable that the upper limit boss 220 and the lower limit boss 620 can accurately control the bonding thickness between the upper substrate 200 and the pressure-sensitive film 400, and between the lower substrate 600 and the pressure-sensitive film 400. Through the limiting effect of the limiting boss, it can be ensured that the glass paste is evenly distributed during the sintering process to form a consistent bonding thickness, thereby ensuring the consistency of the capacitance gap between the upper capacitor Ct310 and the lower capacitor Cb510. Accurately controlling the bonding thickness helps to improve the measurement accuracy of the capacitance value and ensure the high sensitivity and stability of the sensor.

[0062] Reference Figure 1 According to a differential pressure sensor sensitive structure 10 provided by the present invention, the upper substrate 200 is provided with an upper air guide hole 230 penetrating itself along the thickness direction, and the upper air guide hole 230 is connected to the first chamber 300; the lower substrate 600 is provided with a lower air guide hole 630 penetrating itself along the thickness direction, and the lower air guide hole 630 is connected to the second chamber.

[0063] It is understandable that the upper air holes 230 and the lower air holes 630 provide an air channel for the sensor, so that the differential pressure can be transmitted to the chambers on both sides of the pressure-sensitive membrane 400. This is the basic principle of the operation of the differential pressure sensor, that is, detecting pressure changes by measuring the pressure difference between the two chambers. When the differential pressure acts on the sensor, the upper air holes 230 allow the pressure to be transmitted to the first chamber 300, and the lower air holes 630 allow the pressure to be transmitted to the second chamber 500. In this way, a pressure difference will be generated on both sides of the pressure-sensitive membrane 400, causing the pressure-sensitive membrane 400 to deform. Through the air holes, the pressure changes can be quickly transmitted to the pressure-sensitive membrane 400, thereby improving the response speed of the sensor.

[0064] Reference Figure 1According to a differential pressure sensor sensitive structure 10 provided by the present invention, a first electrode pad 430 is arranged on the side of the pressure-sensitive film 400 facing the upper substrate 200, and the first electrode pad 430 is electrically connected to the first electrode 460. A second electrode pad 440 is arranged on the side of the pressure-sensitive film 400 facing the lower substrate 600, and the second electrode pad 440 is electrically connected to the second electrode 470. The first electrode pad 430 and the second electrode pad 440 are electrically connected through the plated side edge 450.

[0065] It can be understood that in this embodiment, electrode pads are arranged on both sides of the pressure-sensitive film 400. The first electrode pad 430 and the second electrode pad 440 provide an electrical connection interface for the first electrode 460 and the second electrode 470, and are electrically connected through the coated side edges 450, thereby ensuring a reliable connection between the electrodes, improving the integrity and transmission quality of the signal, and ensuring the high precision and stability of the sensor.

[0066] Reference Figure 1 According to a differential pressure sensor sensitive structure 10 provided by the present invention, the differential pressure sensor sensitive structure 10 also includes a bonding gold wire 900, and the ASIC conditioning chip 100 is electrically connected to the first electrode 460, the second electrode 470, the upper electrode 240 and the lower electrode 640 respectively through the bonding gold wire 900.

[0067] It can be understood that the bonding gold wire 900 is a bridge connecting the ASIC conditioning chip 100 and the various electrodes (first electrode 460, second electrode 470, upper electrode 240 and lower electrode 640) in the differential pressure sensor sensitive structure 10. The high conductivity and good mechanical properties of the gold wire ensure a stable and reliable electrical connection between the electrode and the ASIC chip. At the same time, the bonding gold wire 900 is also responsible for transmitting electrical signals in the differential pressure sensor sensitive structure 10. The signals include capacitance changes caused by pressure changes, temperature compensation signals, etc. Through the bonding gold wire 900, these signals can be efficiently transmitted to the ASIC conditioning chip 100 for processing and analysis.

[0068] Reference Figures 1 to 8 In a specific embodiment, a stress-isolated differential pressure sensor sensitive structure 10 is used, and the overall structure is as follows Figure 1As shown, the entire differential pressure sensor sensitive structure 10 includes a lower substrate 600, a pressure-sensitive film 400, an upper substrate 200 and an ASIC conditioning chip 100. The gap between the lower substrate 600 and the pressure-sensitive film 400 is defined as d1, and the recommended value is 10um. By defining a metal electrode between the gap, a lower capacitor Cb510 is formed; the gap between the upper substrate 200 and the pressure-sensitive film 400 is defined as d2, and the recommended value is 10um. By defining a metal electrode between the gap, an upper capacitor Ct310 is formed. When the differential mode pressure input from the outside changes, the gap between the upper and lower capacitors changes, and the differential capacitance change is detected by the ASIC conditioning chip 100 to achieve digital output. The three layers of the lower substrate 600, the pressure-sensitive film 400 and the upper substrate 200 are rigidly connected by wafer-level glass paste bonding. A laser scriber or a grinding wheel scriber is used to cut the three-layer combined wafer into bare DIEs. After screening and testing, the bare DIEs with normal functions are bonded to the ASIC conditioning chip 100, and then the lower electrode 640 pad, the first electrode pad 430, the second electrode pad 440 and the upper electrode 240 pad are electrically interconnected with the ASIC chip through gold wire bonding.

[0069] like Figure 2 and Figure 3 As shown, the lower substrate 600 includes a quartz base layer, a lower limiting boss 620, a lower air guide hole 630, a lower electrode 640, a lower electrode 640 pad and a lower material ring 610, and the specific dimensions are shown in Table 1. The quartz base layer adopts Z-cut quartz crystal with a thickness of 1500um~3300um. The lower limit boss 620 is mainly used to limit the thickness of the glass slurry during bonding. The quartz boss can be processed by wet etching, sandblasting or laser etching, and the processing error is plus or minus 1um; the photolithography process or the baffle process is used to realize the graphic definition of the metal electrode, and the metal coating is realized by magnetron sputtering or electron beam evaporation. Cr is used as the seed layer with a thickness of 20 angstroms~200 angstroms, and the Au layer is used as the metal layer with a thickness of 2000 angstroms~5000 angstroms; the feeding ring 210 adopts a high-precision screen printing process to realize the slurry graphic definition, and the bare DIE is processed through debinding, pre-firing, alignment, normal firing and cutting processes. The slurry thickness is accurately controlled by the boss, and the thickness error of the sintered glass slurry is plus or minus 1um.

[0070] Table 1 Structural dimension parameters of the lower substrate (unit: um) like Figure 4 and Figure 5As shown, the pressure-sensitive film 400 includes a first isolation groove 410, a second isolation groove 420, a first electrode 460, a second electrode 470, a coating side edge 450, a first electrode pad 430, a second electrode pad 440 and a gold wire bonding window 480. The specific dimensions are shown in Table 2. The substrate of the pressure-sensitive film 400 adopts a Z-cut quartz crystal with a thickness of 80um~1800um. The isolation groove is an upper and lower double-sided annular cavity. The pattern is defined by double-sided photolithography or double-sided shielding plate process, and wet etching, sandblasting and laser engraving are adopted. The process realizes cavity processing, and targets different cavity processing processes; the first electrode pad 430 and the second electrode pad 440 adopt double-sided photolithography process or double-sided shielding plate process to define metal electrodes, metal pads and metal routing patterns, and metal coating is realized by magnetron sputtering or electron beam evaporation, Cr is used as seed layer with a thickness of 20 angstroms to 200 angstroms, and Au layer is used as metal layer with a thickness of 2000 angstroms to 5000 angstroms; three-dimensional photolithography or shielding plate process is used to realize side edge coating, and electrical connection between the upper and lower pads of the pressure-sensitive film 400 is realized.

[0071] Table 2 Structural dimension parameters of pressure-sensitive membrane (unit: um) This is achieved by ultrasonic drilling or wet etching. When the three-layer structure glass paste is bonded, the stress isolation groove acts as an overflow groove, squeezing the excess paste into the outer edge wall of the stress isolation groove. The relationship between the quartz pressure-sensitive film 400 and the range is shown in Table 3.

[0072] Table 3 Correspondence between pressure-sensitive film and measuring range (unit: um) like Figure 6 , Figure 7 and Figure 8As shown, the upper substrate 200 includes a quartz base layer, an upper limit boss 220, an upper air guide hole 230, an upper electrode 240, an upper electrode 240 pad, a feed ring 210, a gold wire bonding window 250 and an ASIC core, and the specific dimensions are shown in Table 1. The quartz substrate layer uses Z-cut quartz crystal with a thickness of 1000um~2800um. The upper limit boss 220 mainly limits the thickness of the glass paste during bonding. The quartz boss can be processed by wet etching, sandblasting or laser etching, and the processing error is plus or minus 1um. The metal electrode pattern definition is achieved by photolithography or baffle process. The metal coating is achieved by magnetron sputtering or electron beam evaporation. Cr is used as the seed layer with a thickness of 20 angstroms~200 angstroms, and the Au layer is used as the metal layer with a thickness of 2000 angstroms~5000 angstroms. The glass paste ring uses high-precision screen printing process to achieve paste pattern definition, and the bare DIE is processed through debonding, pre-firing, alignment, normal firing and slicing processes. The slurry thickness is accurately controlled by the boss, and the thickness error of the sintered glass paste is plus or minus 1um. The upper air guide hole 230 and the gold wire bonding window 250 are realized by ultrasonic drilling or wet etching process. The ASIC core on the front side of the upper substrate 200 is bonded with epoxy adhesive to realize the patch, and the pressure-sensitive layer electrode and the lower base layer electrode are reserved on the front side, and the electrical connection is realized by gold wire bonding. The structural parameters are shown in Table 4.

[0073] Table 4 Structural dimension parameters of upper substrate (unit: um) Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A differential pressure sensor sensitive structure, characterized in that: The invention comprises an ASIC conditioning chip, an upper substrate, a lower substrate and a pressure-sensitive film, wherein the upper substrate and the lower substrate are arranged opposite to each other and spaced apart, the ASIC conditioning chip is arranged on a side of the upper substrate away from the lower substrate, the pressure-sensitive film is arranged between the upper substrate and the lower substrate, the upper substrate, the pressure-sensitive film and the lower substrate are bonded and connected, a first chamber is formed between the upper substrate and the pressure-sensitive film, and a second chamber is formed between the pressure-sensitive film and the lower substrate; an upper capacitor Ct is formed between the lower electrode of the upper substrate located in the first chamber and the first electrode of the pressure-sensitive film; a lower capacitor Cb is formed between the upper electrode of the lower substrate located in the second chamber and the second electrode of the pressure-sensitive film; wherein an isolation groove is provided on the pressure-sensitive film.

2. The differential pressure sensor sensitive structure according to claim 1, characterized in that: The pressure-sensitive film is provided with a first isolation groove and a second isolation groove symmetrical along its midline plane. The first isolation groove is provided on the side of the pressure-sensitive film facing the upper substrate and is located in the first cavity; the second isolation groove is provided on the side of the pressure-sensitive film facing the lower substrate and is located in the second cavity.

3. The differential pressure sensor sensitive structure according to claim 2, characterized in that: The first isolation groove and the second isolation groove are arranged in a ring shape. The first isolation groove is arranged at intervals on the outer peripheral side of the first electrode, and the second isolation groove is arranged at intervals on the outer peripheral side of the two electrodes.

4. The differential pressure sensor sensitive structure according to claim 2, characterized in that: The angle between the side wall of the first isolation trench or the second isolation trench and the horizontal plane is α, wherein 52°≤α≤90°.

5. The differential pressure sensor sensitive structure according to any one of claims 1 to 4, characterized in that: The upper substrate, the pressure-sensitive film and the lower substrate are bonded and connected by glass paste.

6. The differential pressure sensor sensitive structure according to claim 5, characterized in that: The glass paste includes an upper glass paste layer and a lower glass paste layer. An upper material ring is provided on the side of the upper substrate facing the pressure-sensitive film, and the upper glass paste layer is arranged around the upper material ring to bond the upper substrate and the pressure-sensitive film; a lower material ring is provided on the side of the lower substrate facing the pressure-sensitive film, and the lower glass paste layer is arranged around the lower material ring to bond the lower substrate and the pressure-sensitive film.

7. The differential pressure sensor sensitive structure according to claim 5, characterized in that: The outer peripheral edge of the upper substrate facing the pressure-sensitive film is protruded with a plurality of upper limit bosses, and the plurality of upper limit bosses are evenly arranged along the peripheral side of the pressure-sensitive film; And / or, a plurality of lower limit bosses are protruding from an outer peripheral edge of the lower substrate on one side facing the pressure-sensitive film, and the plurality of lower limit bosses are evenly arranged along the peripheral side of the pressure-sensitive film.

8. The differential pressure sensor sensitive structure according to any one of claims 1 to 4, characterized in that: The upper substrate is provided with an upper air guide hole penetrating the upper substrate along the thickness direction, and the upper air guide hole is connected with the first chamber; and / or, The lower substrate is provided with a lower air guide hole penetrating the lower substrate along the thickness direction, and the lower air guide hole is communicated with the second chamber.

9. The differential pressure sensor sensitive structure according to any one of claims 1 to 4, characterized in that: A first electrode pad is arranged on the side of the pressure-sensitive film facing the upper substrate, and the first electrode pad is electrically connected to the first electrode. A second electrode pad is arranged on the side of the pressure-sensitive film facing the lower substrate, and the second electrode pad is electrically connected to the second electrode. The first electrode pad and the second electrode pad are electrically connected through the side edges of the coating.

10. The differential pressure sensor sensitive structure according to any one of claims 1 to 4, characterized in that: The differential pressure sensor sensitive structure further includes bonding gold wires, and the ASIC conditioning chip is electrically connected to the first electrode, the second electrode, the upper electrode and the lower electrode respectively through the bonding gold wires.

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