Pressure sensor and preparation method thereof

Abstract

The invention relates to the technical field of pressure sensors, and provides a pressure sensor and a preparation method thereof. The pressure sensor comprises an upper pole plate, a pressure sensing film and a metal base. The upper pole plate is made of an aluminum oxide crystal material; the pressure sensing film is made of an aluminum oxide crystal material and is arranged on one side of the upper polar plate, and the pressure sensing film and the upper polar plate form a capacitor structure; the metal base is arranged on one side, deviating from the upper polar plate, of the pressure-sensitive film and used for supporting the upper polar plate and the pressure-sensitive film; wherein the upper pole plate is provided with a pole plate gap, the upper pole plate is in direct bonding connection with the pressure sensing film, and the pressure sensing film is in direct bonding connection with the metal base. The high-temperature-resistant corrosion-resistant pressure sensor overcomes the defects that in the prior art, a pressure sensor is prone to generating stress in a high-temperature environment, so that the zero-bias stability of the sensor is poor, and the precision is reduced after long-term use, and the high-temperature-resistant corrosion-resistant pressure sensor is achieved.

Description

Technical Field

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

[0002] Pressure sensors are widely used in semiconductor, chemical, energy and other fields, especially in high temperature and corrosive gas environments, which place higher requirements on the stability, corrosion resistance and accuracy of sensors.

[0003] Currently, pressure sensors for high-temperature, corrosive environments primarily use metal thin films or ceramic materials as pressure-sensing membranes. While metal thin-film sensors offer high sensitivity, they are susceptible to mechanical fatigue and corrosion under long-term exposure to high temperatures and corrosive gases, leading to performance degradation. Ceramic sensors, while corrosion-resistant, have lower sensitivity due to the high hardness and low strain characteristics of ceramics. Furthermore, during the manufacturing process, thermal expansion coefficient mismatches can easily generate stress, affecting sensor stability and accuracy.

[0004] Prior art pressure sensors used in high-temperature, corrosive environments commonly suffer from the following technical issues: Due to the mismatch in thermal expansion coefficients between the pressure-sensing membrane and the electrode plate materials, stress is easily generated in high-temperature environments, resulting in poor sensor bias stability and decreased accuracy over long-term use. Therefore, a high-stability pressure sensor and its fabrication method that can address these issues are urgently needed. Summary of the Invention

[0005] The present invention provides a pressure sensor and a preparation method thereof, which are used to solve the defects of the pressure sensor in the prior art that stress is easily generated in a high temperature environment, resulting in poor zero bias stability of the sensor and decreased accuracy after long-term use, thereby realizing a high-temperature and corrosion-resistant pressure sensor.

[0006] The present invention provides a pressure sensor, comprising: The upper plate is made of aluminum oxide crystal material; A pressure-sensitive film is made of aluminum oxide crystal material, and is provided on one side of the upper plate and forms a capacitor structure with the upper plate; A metal base is provided on a side of the pressure-sensitive film away from the upper electrode plate, and is used to support the upper electrode plate and the pressure-sensitive film; Wherein, the upper electrode plate is provided with an electrode gap, the upper electrode plate is directly bonded to the pressure-sensitive film, and the pressure-sensitive film is directly bonded to the metal base.

[0007] According to a pressure sensor provided by the present invention, the upper plate includes an upper plate body, a pressure-sensitive cavity is provided on a side of the upper plate body facing the pressure-sensitive film, and the pressure-sensitive cavity constitutes the plate gap; The pressure-sensitive film includes a pressure-sensitive film body, and the pressure-sensitive film body is arranged on one side of the upper electrode body; The metal base includes a metal base body, which is arranged on the side of the pressure-sensitive membrane body away from the upper plate body. A process hole is provided in the middle of the metal base body, and the diameter of the process hole is larger than the diameter of the pressure-sensitive cavity.

[0008] According to a pressure sensor provided by the present invention, a groove is provided on a side of the metal base body facing the pressure-sensitive membrane body, a boss is provided between the groove and the process hole, and the pressure-sensitive membrane body is provided on the boss.

[0009] According to a pressure sensor provided by the present invention, the capacitor structure includes: A pressure-sensitive capacitor structure, used to convert the deformation of the pressure-sensitive film into an electrical signal; The differential capacitor structure is coaxially arranged with the pressure-sensing capacitor structure and located on the periphery of the pressure-sensing capacitor structure, and is used to purify the effective electrical signal.

[0010] According to a pressure sensor provided by the present invention, the pressure-sensing capacitor structure includes: A pressure-sensitive electrode of the pressure-sensitive film is provided at the center of the side of the pressure-sensitive film body facing the upper electrode plate body; The upper plate pressure-sensitive electrode is arranged at the center of the bottom of the pressure-sensitive cavity and is corresponding to the pressure-sensitive electrode of the pressure-sensitive film.

[0011] According to a pressure sensor provided by the present invention, the differential capacitance structure includes: a pressure-sensitive film differential electrode, provided on the side of the pressure-sensitive film body facing the upper plate body, and electrically connected to the pressure-sensitive film pressure-sensitive electrode through the first pressure-sensitive film common electrode conductive area; The upper plate differential electrode is disposed at the bottom of the pressure-sensing cavity and is corresponding to the pressure-sensing film differential electrode.

[0012] A pressure sensor provided according to the present invention further includes: A pressure-sensitive film common electrode lead pin, electrically connected to the first pressure-sensitive film common electrode conductive area; An upper plate differential electrode lead pin, electrically connected to the upper plate differential electrode; The upper plate pressure-sensitive electrode lead pin is electrically connected to the upper plate pressure-sensitive electrode.

[0013] A pressure sensor provided according to the present invention further includes: The upper cover is sealed and connected to one side of the metal base. The common electrode lead pin of the pressure-sensitive film, the differential electrode lead pin of the upper plate, and the pressure-sensitive electrode lead pin of the upper plate all pass through the upper cover. The upper cover includes: A cover cavity is provided inside the upper cover, wherein the upper electrode plate and the pressure-sensitive film are both sealed inside the cover cavity; A suction needle is inserted through the top of the upper cover and is used to draw a vacuum into the interior of the cover cavity; Structural regulation, said structural regulation including: A catheter having an airway inside for communicating with the outside; The gauge seat is arranged at one end of the conduit and is sealed with the metal base body. A ventilation cavity is provided inside the gauge seat. One end of the ventilation cavity is connected to the air duct, and the other end is connected to the process hole.

[0014] A pressure sensor provided according to the present invention further includes: A second pressure-sensitive film common electrode conductive area is provided on a side of the upper plate body away from the pressure-sensitive film, one end of the second pressure-sensitive film common electrode conductive area is electrically connected to the first pressure-sensitive film common electrode conductive area via a pressure-sensitive film common electrode lead-out hole provided on the upper plate body, and the other end is electrically connected to the pressure-sensitive film common electrode lead-out pin; An upper plate differential electrode conductive area is provided on one side of the second pressure-sensitive film common electrode conductive area, one end of the upper plate differential electrode conductive area is electrically connected to the upper plate differential electrode through an upper plate differential electrode lead-out hole provided on the upper plate body, and the other end is electrically connected to the upper plate differential electrode lead-in pin; The upper plate pressure-sensitive electrode conductive area is arranged on the other side of the second pressure-sensitive film common electrode conductive area, one end of the upper plate pressure-sensitive electrode conductive area is electrically connected to the upper plate pressure-sensitive electrode through the upper plate pressure-sensitive electrode lead-out hole arranged on the upper plate body, and the other end is electrically connected to the upper plate pressure-sensitive electrode lead pin.

[0015] The present invention also provides a method for preparing a pressure sensor, comprising: The upper electrode plate and the pressure-sensitive film are prepared using aluminum oxide crystal material; A plate gap is formed on the upper plate by a layer-by-layer peeling process; Electrodes are plated on the upper plate and the pressure-sensitive film; preparing a metal base; Connect the upper plate, the pressure-sensitive film and the metal base through a direct bonding process; Complete the rest of the pressure sensor assembly.

[0016] The pressure sensor and preparation method provided by the present invention adopt aluminum oxide crystal as the unified material of the pressure-sensitive membrane and the electrode plate. This method avoids the problem of thermal expansion coefficient mismatch caused by the introduction of other materials through the subsequent sealing process, ensures stress matching in the full temperature range, and improves the zero-bias stability of the product. The excellent high-temperature resistance and corrosion resistance of aluminum oxide crystal enable it to work stably for a long time in a high-temperature environment above 150°C and in corrosive gases such as chlorine and fluorine. Secondly, the pressure-sensitive membrane, the electrode plate and the metal base are connected through a direct bonding process. This direct bonding method can achieve high-strength sealing without introducing new sealing materials, avoiding the risk of corrosion penetration of traditional glass paste in a corrosive environment, and achieving the purpose of corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to 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 any creative work.

[0018] Figure 1 This is a first-direction exploded view of the pressure sensor and its preparation method provided by the present invention.

[0019] Figure 2 This is a second-direction exploded view of the pressure sensor and the preparation method thereof provided by the present invention.

[0020] Figure 3 It is a cross-sectional view of the pressure sensor and the preparation method thereof provided by the present invention.

[0021] Figure 4 It is an assembly diagram of the pressure sensor provided by the present invention and its preparation method.

[0022] Figure 5 It is a bottom view of the upper electrode plate of the pressure sensor and the preparation method thereof provided by the present invention.

[0023] Figure 6 It is a top view of the upper electrode plate of the pressure sensor and the preparation method thereof provided by the present invention.

[0024] Figure 7 It is a top view of the pressure-sensitive film of the pressure sensor and the preparation method thereof provided by the present invention.

[0025] Figure 8 It is a schematic diagram of the internal structure of the pressure sensor and its preparation method provided by the present invention.

[0026] Reference numerals: 100: Upper plate; 110: Upper plate body; 111: Pressure-sensing cavity; 112: Upper plate differential electrode; 113: Upper plate pressure-sensing electrode; 114: Upper plate pressure-sensing electrode lead-out hole; 115: Upper plate differential electrode lead-out hole; 116: Pressure-sensing film common electrode lead-out hole; 120: Upper plate differential electrode conductive area; 130: Second pressure-sensing film common electrode conductive area; 140: Upper plate pressure-sensing electrode conductive area; 200: pressure-sensitive film; 210: pressure-sensitive film body; 220: pressure-sensitive film differential electrode; 230: pressure-sensitive film pressure-sensitive electrode; 240: first pressure-sensitive film common electrode conductive area; 300: metal base; 310: metal base body; 320: groove; 330: boss; 340: process hole; 400: Structural regulation; 410: Catheter; 420: Regulation seat; 430: Ventilation channel; 440: Ventilation cavity; 500: upper cover; 520: suction needle; 510: cover cavity; 610: Common electrode lead pin of pressure-sensitive film; 620: Upper plate differential electrode lead pin; 630: Upper plate pressure-sensitive electrode lead pin. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0028] The following combination Figures 1-8 The structure and working principle of the present invention are described.

[0029] Reference Figure 1 The present invention provides a pressure sensor comprising an upper plate 100, a pressure-sensitive film 200, and a metal base 300. The upper plate 100 is made of aluminum oxide crystal material; the pressure-sensitive film 200 is made of aluminum oxide crystal material, is disposed on one side of the upper plate 100, and forms a capacitor structure with the upper plate 100; the metal base 300 is disposed on the side of the pressure-sensitive film 200 facing away from the upper plate 100, and is used to support the upper plate 100 and the pressure-sensitive film 200; wherein, the upper plate 100 is provided with a plate gap, the upper plate 100 and the pressure-sensitive film 200 are directly bonded, and the pressure-sensitive film 200 is directly bonded to the metal base 300.

[0030] Specifically, the upper plate 100 and the pressure-sensitive film 200, as well as the pressure-sensitive film 200 and the metal base 300, are all directly bonded to form a capacitor structure, such as laser bonding. The bonding process is carried out at room temperature, using a laser beam focused on the contact interface of the two components. The photothermal effect causes instantaneous local melting of the contact surface material, forming a plasma for fusion, and then rapidly cooling and solidifying to achieve atomic-level bonding. Before bonding, the contact surfaces of the upper plate 100, the pressure-sensitive film 200 and the metal base 300 must be precisely polished to a mirror-grade finish, and plasma cleaning and activation must be performed to ensure a clean surface. Laser direct bonding does not require intermediate materials, and by precisely controlling the laser energy and scanning path, high-strength, high-tightness connections can be achieved at room temperature.

[0031] The present invention adopts aluminum oxide crystals as a unified material for the pressure-sensitive membrane and the electrode plate. This method avoids the problem of thermal expansion coefficient mismatch caused by the introduction of other materials through the subsequent sealing process, ensures stress matching in the full temperature range, and improves the zero-bias stability of the product. The excellent high-temperature resistance and corrosion resistance of aluminum oxide crystals enable it to work stably for a long time in high-temperature environments above 150°C and in corrosive gases such as chlorine and fluorine. Secondly, the pressure-sensitive membrane, the electrode plate and the metal base are connected through a direct bonding process. This direct bonding method can achieve high-strength sealing without introducing new sealing materials, avoiding the risk of corrosion penetration of traditional glass pastes in corrosive environments, and achieving the purpose of corrosion resistance.

[0032] Reference Figure 1 and Figure 2 In some embodiments of the present invention, the upper plate 100 includes an upper plate body 110, and a pressure-sensitive cavity 111 is provided on the side of the upper plate body 110 facing the pressure-sensitive film 200, and the pressure-sensitive cavity 111 constitutes a plate gap; the pressure-sensitive film 200 includes a pressure-sensitive film body 210, and the pressure-sensitive film body 210 is provided on one side of the upper plate body 110; the metal base 300 includes a metal base body 310, and the metal base body 310 is provided on the side of the pressure-sensitive film body 210 facing away from the upper plate body 110, and a process hole 340 is provided in the middle of the metal base body 310, and the diameter of the process hole 340 is larger than the diameter of the pressure-sensitive cavity 111.

[0033] Specifically, the upper plate body 110 and the pressure-sensing membrane body 210 are fixedly connected via direct laser bonding. The bonding surface is an annular planar area surrounding the pressure-sensing cavity 111. The pressure-sensing membrane body 210 and the metal base body 310 are also connected via direct laser bonding. The bonding surface is located in the annular contact area between the lower surface of the pressure-sensing membrane body 210 and the upper surface of the metal base body 310. During the laser bonding process, each contact surface is precision-polished to a mirror finish. A focused laser beam is then used to scan the contact surface material, causing it to melt instantaneously and form an atomic-level bond. The metal base body 310 is made of Kovar alloy, whose thermal expansion coefficient matches that of aluminum oxide crystals. The process hole 340 is coaxial with the pressure-sensing cavity 111. The difference in diameter between the two ensures that the pressure-sensing membrane body 210 is not affected by deformation. The pressure-sensing cavity 111 of the upper plate body 110 is formed using a layer-by-layer laser peeling process. The cavity sidewalls have a slight taper to facilitate demolding.

[0034] This embodiment provides the necessary space for the deformation of the pressure-sensitive film body 210 by setting a pressure-sensitive cavity 111 on the upper electrode body 110. When external pressure acts, the pressure-sensitive film body 210 produces elastic deformation in the direction of the pressure-sensitive cavity 111, changing the capacitance value between it and the upper electrode body 110. The change is converted into an electrical signal output by the detection circuit. Laser direct bonding technology realizes high-strength connection between the upper electrode body 110 and the pressure-sensitive film body 210, and the pressure-sensitive film body 210 and the metal base body 310, avoiding the failure problem of traditional connection methods in high temperature environments. The pressure-sensitive cavity 111 is processed and formed by a laser layer-by-layer peeling process to achieve controllable plate gap between the upper electrode body 110 and the pressure-sensitive film body 210.

[0035] Reference Figure 2 In some embodiments of the present invention, a groove 320 is provided on the side of the metal base body 310 facing the pressure-sensitive membrane body 210 , a boss 330 is provided between the groove 320 and the process hole 340 , and the pressure-sensitive membrane body 210 is provided on the boss 330 .

[0036] Specifically, the groove 320 and the boss 330 of the metal base body 310 are integrally formed through precision machining, and the pressure-sensitive membrane body 210 is fixed to the upper surface of the boss 330 by direct laser bonding. During the laser bonding process, the contact surface between the pressure-sensitive membrane body 210 and the boss 330 is precisely polished to a mirror finish, and then a focused laser beam is used to scan the contact surface material to cause instantaneous melting and form an atomic-level bond. The groove 320 is arranged around the boss 330 and is connected to the pressure-sensitive cavity 111. The process hole 340 is located in the center area of ​​the boss 330, and its diameter is larger than the diameter of the pressure-sensitive cavity 111 to ensure deformation space for the pressure-sensitive membrane body 210.

[0037] This embodiment utilizes the design of boss 330 to provide a precise positioning and support platform for the pressure-sensing membrane body 210. When external pressure is applied, the pressure-sensing membrane body 210 elastically deforms toward the pressure-sensing cavity 111, using boss 330 as a fulcrum. This changes the capacitance between the membrane body 210 and the upper plate body 110, which is converted into an electrical signal by the detection circuit. The groove 320 effectively reduces stress concentration in the bonding area, improving connection reliability.

[0038] Reference Figures 1 to 3 In some embodiments of the present invention, the capacitor structure includes a pressure-sensing capacitor structure and a differential capacitor structure. The pressure-sensing capacitor structure is used to convert the deformation of the pressure-sensing film 200 into an electrical signal. The differential capacitor structure is coaxially arranged with the pressure-sensing capacitor structure and located on the periphery of the pressure-sensing capacitor structure to purify the effective electrical signal.

[0039] Specifically, the pressure-sensitive capacitor structure is composed of the central electrode area of ​​the upper plate body 110 and the corresponding area of ​​the pressure-sensitive film body 210, and the two are maintained in a parallel and opposing relationship through precise assembly. The central electrode area is formed on the lower surface of the upper plate body 110 through a metallization process, and its diameter matches the pressure-sensitive cavity 111. The differential capacitor structure is composed of the peripheral annular electrode of the upper plate body 110 and the peripheral area of ​​the pressure-sensitive film body 210, and the annular electrodes are spaced apart from the center electrodes. In the above structure, the initial plate spacing of the pressure-sensitive capacitor structure and the differential capacitor structure is determined by the depth of the pressure-sensitive cavity 111.

[0040] This embodiment achieves high-precision pressure measurement through a coaxially integrated pressure-sensitive capacitor structure and a differential capacitor structure. When pressure acts on the pressure-sensitive membrane body 210, the change in the plate spacing of the pressure-sensitive capacitor structure causes the capacitance value to change, while the differential capacitor structure synchronously detects the environmental interference signal. The signal processing circuit eliminates common-mode interference through differential amplification technology and extracts the effective pressure signal. The precision assembly process ensures the parallelism and spacing accuracy of the capacitor plates, and the mechanical fixing method provides reliable connection strength. The dual-capacitor structure design enables the sensor to maintain high sensitivity while reducing the influence of other factors such as temperature. The actual capacitance is the capacitance of the pressure-sensitive capacitor structure minus the capacitance of the differential capacitor structure.

[0041] Reference Figures 1 to 3 In some embodiments of the present invention, the pressure-sensitive capacitor structure includes a pressure-sensitive film pressure-sensitive electrode 230 and a top plate pressure-sensitive electrode 113. The pressure-sensitive film pressure-sensitive electrode 230 is located in the center of the pressure-sensitive film body 210 on the side facing the top plate body 110; the top plate pressure-sensitive electrode 113 is located in the center of the bottom of the pressure-sensitive cavity 111 and corresponds to the pressure-sensitive film pressure-sensitive electrode 230.

[0042] The differential capacitor structure includes a pressure-sensitive film differential electrode 220 and a top plate differential electrode 112. The pressure-sensitive film differential electrode 220 is located on the side of the pressure-sensitive film body 210 facing the top plate body 110 and is electrically connected to the pressure-sensitive film pressure-sensitive electrode 230 via the first pressure-sensitive film common electrode conductive area 240. The top plate differential electrode 112 is located at the bottom of the pressure-sensitive cavity 111 and corresponds to the pressure-sensitive film differential electrode 220.

[0043] Specifically, the pressure-sensitive film pressure-sensitive electrode 230 is fixedly arranged in the central area of ​​the upper surface of the pressure-sensitive film body 210 through a vacuum coating process, and its edge is electrically connected to the pressure-sensitive film differential electrode 220 through the first pressure-sensitive film common electrode conductive area 240. The upper plate pressure-sensitive electrode 113 is fixedly arranged in the central position of the bottom of the pressure-sensitive cavity 111 by a sputtering coating process, and maintains a parallel opposing relationship with the pressure-sensitive film pressure-sensitive electrode 230. The upper plate differential electrode 112 is formed by a photolithography process and is fixedly arranged in the peripheral area of ​​the bottom of the pressure-sensitive cavity 111, and an insulating isolation zone is provided between the upper plate pressure-sensitive electrode 113. The pressure-sensitive film differential electrode 220 is fixedly arranged in the peripheral area of ​​the upper surface of the pressure-sensitive film body 210 by a mask evaporation process, and its shape corresponds to the upper plate differential electrode 112. In the above structure, all electrodes are connected to the base material by metallurgical bonding to ensure reliable electrical connection performance in a high temperature environment.

[0044] This embodiment achieves high-precision pressure detection by separately arranged pressure-sensitive electrodes and differential electrodes. When external pressure acts, the pressure-sensitive film body 210 is deformed, resulting in a change in the plate spacing between the pressure-sensitive film pressure-sensitive electrode 230 and the upper plate pressure-sensitive electrode 113, causing the pressure-sensitive capacitance value to change. At the same time, the differential capacitance structure formed by the pressure-sensitive film differential electrode 220 and the upper plate differential electrode 112 detects environmental interference signals. By using the first pressure-sensitive film common electrode conductive area 240 as a common connection end, the synchronous acquisition of the pressure-sensitive signal and the differential signal on the pressure-sensitive film body 210 can be achieved. The spacing between the upper plate pressure-sensitive electrode 112 and the upper plate pressure-sensitive electrode 113 can achieve independent signal acquisition of the two.

[0045] Reference Figure 1 、 Figure 2 and Figure 4 In some embodiments of the present invention, the pressure sensor further includes a pressure-sensitive film common electrode lead pin 610, a top plate differential electrode lead pin 620, and a top plate pressure-sensitive electrode lead pin 630. The pressure-sensitive film common electrode lead pin 610 is electrically connected to the first pressure-sensitive film common electrode conductive region 240; the top plate differential electrode lead pin 620 is electrically connected to the top plate differential electrode 112; and the top plate pressure-sensitive electrode lead pin 630 is electrically connected to the top plate pressure-sensitive electrode 113.

[0046] Specifically, the pressure-sensitive film common electrode lead pin 610 is fixedly connected to the lead-out end of the first pressure-sensitive film common electrode conductive area 240 by conductive silver paste, and the connection part adopts a thermal curing process to enhance the bonding strength. The upper plate differential electrode lead pin 620 is fixedly connected to the extended conductive band of the upper plate differential electrode 112 by a micro-spot welding process, and the welding point is located in the edge area of ​​the upper plate body 110. The upper plate pressure-sensitive electrode lead pin 630 is connected to the lead-out end of the upper plate pressure-sensitive electrode 113 by a gold wire ball welding process, and the welding point is formed in the dedicated pad area outside the pressure-sensitive cavity 111. In the above structure, the connection part between each lead pin and the electrode is provided with an insulating protective layer to avoid short circuit between adjacent lead pins. The lead pin is made of nickel-based alloy material, and its thermal expansion coefficient matches that of the ceramic substrate to ensure connection reliability when the temperature changes.

[0047] This embodiment achieves reliable signal transmission through an optimized electrode pin layout. The pressure-sensitive film common electrode pin 610 serves as a common reference end and provides electrical connection for the pressure-sensitive film pressure-sensitive electrode 230 and the pressure-sensitive film differential electrode 220. The upper plate differential electrode pin 620 and the upper plate pressure-sensitive electrode pin 630 transmit differential signals and pressure-sensitive signals respectively. When it is necessary to measure the pressure-sensitive capacitance, it is only necessary to measure the pressure-sensitive film common electrode pin 610 and the upper plate pressure-sensitive electrode pin 630. Similarly, when it is necessary to measure the differential capacitance, it is only necessary to measure the pressure-sensitive film common electrode pin 610 and the upper plate differential electrode pin 620.

[0048] Reference Figure 1 and Figure 2 In some embodiments of the present invention, the pressure sensor further includes an upper cover 500 and a structural regulator 400. The upper cover 500 is sealed and connected to one side of the metal base 300. The pressure-sensing film common electrode lead pin 610, the upper plate differential electrode lead pin 620, and the upper plate pressure-sensing electrode lead pin 630 all pass through the upper cover 500. The upper cover 500 includes a cover cavity 510 and an air suction lead pin 520. The cover cavity 510 is disposed inside the upper cover 500. The upper plate 100 and the pressure-sensing film 200 are both sealed inside the cover cavity 510. The air suction lead pin 520 passes through the top of the upper cover 500 and is used to evacuate the interior of the cover cavity 510. Structural gauge 400 includes a conduit 410 and a gauge base 420. Conduit 410 has an internal vent 430 for communication with the outside. Gauge base 420 is located at one end of conduit 410 and is sealed to metal base body 310. Gauge base 420 has a vent cavity 440 within it, one end of which communicates with vent 430 and the other end with process hole 340.

[0049] Specifically, the upper cover 500 is laser-welded to the open end of the metal base 300 to form an annular seal. The weld is located between the upper edge of the metal base 300 and the lower end surface of the upper cover 500. The cover cavity 510 is precision-machined to form an open-bottomed cavity within the upper cover 500. Its inner wall surface is polished to reduce gas adsorption. The suction pin 520 is made of Kovar alloy and is fixed through the top of the upper cover 500 using a glass-sealed process, forming an airtight insulating structure at the seal. The conduit 410 of the structural gauge 400 is laser-welded to the gauge base 420. The gauge base 420 is electron-beam-welded to form an annular seal with the metal base body 310. The weld is located between the end surface of the gauge base 420 and the sidewall of the metal base body 310. A vent cavity 440 is drilled into the gauge base 420, its axis coaxially aligned with the vent channel 430 of the conduit 410. In the above structure, all sealed connection parts are leak tested by helium mass spectrometry to ensure that the leakage rate meets the high vacuum requirements.

[0050] This embodiment achieves long-term maintenance of a high vacuum environment through a sealing structure. Laser welding of the upper cover 500 and the metal base 300 forms a primary sealing barrier, sealing the upper electrode 100 and the pressure-sensitive membrane 200 inside the cover cavity 510. The interior of the cover cavity 510 and the pressure-sensitive cavity 111 is evacuated to a vacuum through the suction needle 520 (and it is ensured that in this state, the pressure-sensitive membrane body 210 is in a flat state). The vent 430 and the vent cavity 440 of the structural regulator 400 constitute a pressure transmission channel, which balances the pressure of the process hole 340 with that of the external environment. When measurement is required, it is necessary to pass the gas through the vent 430 and the vent cavity 440 into the process hole 340, and then act on the lower side of the pressure-sensitive membrane body 210, thereby changing the capacitance.

[0051] Reference Figures 1 to 8In some embodiments of the present invention, the pressure sensor further includes an upper plate differential electrode conductive area 120, a second pressure-sensitive film common electrode conductive area 130, and an upper plate pressure-sensitive electrode conductive area 140. The second pressure-sensitive film common electrode conductive area 130 is provided on the side of the upper plate body 110 away from the pressure-sensitive film 200. One end of the second pressure-sensitive film common electrode conductive area 130 is electrically connected to the first pressure-sensitive film common electrode conductive area 240 through the pressure-sensitive film common electrode lead-out hole 116 provided on the upper plate body 110, and the other end is electrically connected to the pressure-sensitive film common electrode lead-out pin 610. The upper plate differential electrode conductive area 120 is provided on one side of the second pressure-sensitive film common electrode conductive area 130. One end of the upper plate differential electrode conductive area 120 is electrically connected to the first pressure-sensitive film common electrode conductive area 240 through the pressure-sensitive film common electrode lead-out hole 116 provided on the upper plate body 110. The upper plate differential electrode lead-out hole 115 provided on the upper plate body 110 is electrically connected to the upper plate differential electrode 112, and the other end is electrically connected to the upper plate differential electrode lead pin 620; the upper plate pressure-sensitive electrode conductive area 140 is provided on the other side of the second pressure-sensitive film common electrode conductive area 130, and one end of the upper plate pressure-sensitive electrode conductive area 140 is electrically connected to the upper plate pressure-sensitive electrode 113 through the upper plate pressure-sensitive electrode lead-out hole 114 provided on the upper plate body 110, and the other end is electrically connected to the upper plate pressure-sensitive electrode lead pin 630.

[0052] Specifically, the second pressure-sensitive film common electrode conductive area 130, the upper plate differential electrode conductive area 120 and the upper plate pressure-sensitive electrode conductive area 140 are all provided on the upper surface of the upper plate body 110 using the same thick film process, and the process is not limited to printing, hard mask evaporation or photolithography. The pressure-sensitive film common electrode lead-out hole 116, the upper plate differential electrode lead-out hole 115 and the upper plate pressure-sensitive electrode lead-out hole 114 are all processed and formed using a precision drilling process, and the inner wall of the hole is metallized and connected by side evaporation. The connection between each conductive area and the corresponding electrode is achieved by filling with conductive silver paste to ensure the reliability of the electrical connection. The surface of the conductive area is covered with the same insulating protective layer, and only the pad area connected to the lead pin is exposed. In the above structure, the width and spacing of each conductive area remain consistent, forming a symmetrical layout to ensure the consistency of signal transmission characteristics.

[0053] This embodiment achieves stable signal transmission performance through a standardized conductive area design. The second pressure-sensitive film common electrode conductive area 130 serves as a common reference end and forms a vertical interconnection with the first pressure-sensitive film common electrode conductive area 240 through the pressure-sensitive film common electrode lead-out hole 116. The upper plate differential electrode conductive area 120 and the upper plate pressure-sensitive electrode conductive area 140 transmit differential signals and pressure-sensitive signals respectively, and the three are manufactured using the same process parameters. The unified thick film process ensures that each conductive area has consistent conductivity and temperature characteristics. The precision drilling and evaporation metallization processes ensure the connection reliability between each lead-out hole and the electrode.

[0054] The present invention also provides a method for preparing a pressure sensor, comprising the following steps: S1, preparing the upper electrode plate 100 and the pressure-sensitive film 200 using aluminum oxide crystal material; S2, forming a plate gap on the upper plate 100 by a layer-by-layer peeling process; S3, plating electrodes on the upper electrode plate 100 and the pressure-sensitive film 200; S4, preparing a metal base 300; S5, connecting the upper plate 100, the pressure-sensitive film 200 and the metal base 300 through a direct bonding process; S6. Complete the rest of the assembly of the pressure sensor.

[0055] Specifically, in step S1, the upper electrode plate 100 and the pressure-sensitive film 200 are prepared using a laser cutting process using single-crystal aluminum oxide material, and the cut surface is mechanically ground and polished to achieve optical-grade flatness. The layer-by-layer peeling process in step S2 uses a laser focused on the surface of the upper electrode body 110, and by controlling the laser energy density, the material is vaporized point by point, forming a pressure-sensitive cavity 111 with precise depth control. The electrode plating in step S3 adopts a magnetron sputtering process, first depositing a chromium-nickel alloy transition layer on the surface of the substrate, and then plating a gold electrode layer. The electrode pattern is formed by laser etching. The metal base 300 in step S4 is processed using a CNC machine tool to make a Kovar alloy billet, and the surface is electrolytically polished after processing. The direct bonding process in step S5 is carried out in a room temperature atmospheric environment. After the bonding surface is treated with plasma activation, uniform pressure is applied to achieve atomic-level bonding. The assembly in step S6 includes processes such as lead pin welding, vacuum packaging, and performance testing.

[0056] In other possible embodiments, the layer-by-layer peeling process of step S2 can be replaced by a laser-induced chemical etching method. In this embodiment, precise material removal is achieved through a laser-activated chemical etching reaction. The laser beam is focused on the surface of the upper electrode body 110 and cooperates with the etching gas to achieve higher-precision cavity processing. This method reduces the side wall roughness to the nanometer level, thereby improving the dimensional accuracy of the pressure-sensing cavity 111. The heat-affected zone generated by the chemical etching process is smaller, thereby avoiding damage to the microstructure of the material. While maintaining processing efficiency, this embodiment improves the cavity depth uniformity by 30%, further improving the sensitivity and linearity of the sensor. This method is particularly suitable for the processing of ultra-thin pressure-sensitive films, and provides a new process option for the manufacture of miniaturized sensors.

[0057] 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 various embodiments of the present invention.

Claims

1. A pressure sensor, characterized in that: include: The upper electrode plate (100) is made of aluminum oxide crystal material; A pressure-sensitive film (200) is made of aluminum oxide crystal material, the pressure-sensitive film (200) is provided on one side of the upper electrode plate (100), and forms a capacitor structure with the upper electrode plate (100); a metal base (300), provided on a side of the pressure-sensitive film (200) facing away from the upper electrode plate (100), and used for supporting the upper electrode plate (100) and the pressure-sensitive film (200); The upper electrode plate (100) is provided with an electrode gap, the upper electrode plate (100) is directly bonded to the pressure-sensitive film (200), and the pressure-sensitive film (200) is directly bonded to the metal base (300).

2. The pressure sensor according to claim 1, wherein The upper electrode plate (100) comprises an upper electrode plate body (110), a pressure-sensitive cavity (111) is provided on a side of the upper electrode plate body (110) facing the pressure-sensitive film (200), and the pressure-sensitive cavity (111) constitutes the electrode gap; The pressure-sensitive film (200) comprises a pressure-sensitive film body (210), and the pressure-sensitive film body (210) is arranged on one side of the upper electrode plate body (110); The metal base (300) comprises a metal base body (310), the metal base body (310) being arranged on a side of the pressure-sensing membrane body (210) facing away from the upper plate body (110), a process hole (340) being provided in the middle of the metal base body (310), and the diameter of the process hole (340) being larger than the diameter of the pressure-sensing cavity (111).

3. The pressure sensor according to claim 2, wherein: A groove (320) is provided on one side of the metal base body (310) facing the pressure-sensitive membrane body (210), a boss (330) is provided between the groove (320) and the process hole (340), and the pressure-sensitive membrane body (210) is provided on the boss (330).

4. The pressure sensor according to claim 2, wherein: The capacitor structure includes: A pressure-sensitive capacitor structure, used for converting the deformation of the pressure-sensitive film (200) into an electrical signal; The differential capacitor structure is coaxially arranged with the pressure-sensing capacitor structure and located on the periphery of the pressure-sensing capacitor structure, and is used to purify the effective electrical signal.

5. The pressure sensor according to claim 4, characterized in that The pressure-sensitive capacitor structure includes: A pressure-sensitive film pressure-sensitive electrode (230) is provided at the center of the pressure-sensitive film body (210) on a side facing the upper electrode plate body (110); The upper plate pressure-sensitive electrode (113) is arranged at the center of the bottom of the pressure-sensitive cavity (111) and is arranged corresponding to the pressure-sensitive film pressure-sensitive electrode (230).

6. The pressure sensor according to claim 5, characterized in that The differential capacitor structure includes: A pressure-sensitive film differential electrode (220) is provided on the side of the pressure-sensitive film body (210) facing the upper electrode body (110), and is electrically connected to the pressure-sensitive film pressure-sensitive electrode (230) via a first pressure-sensitive film common electrode conductive area (240); The upper plate differential electrode (112) is provided at the bottom of the pressure-sensing cavity (111) and is arranged corresponding to the pressure-sensing film differential electrode (220).

7. The pressure sensor according to claim 6, characterized in that Also includes: A pressure-sensitive film common electrode lead pin (610) electrically connected to the first pressure-sensitive film common electrode conductive area (240); An upper plate differential electrode lead pin (620) electrically connected to the upper plate differential electrode (112); The upper plate pressure-sensitive electrode lead pin (630) is electrically connected to the upper plate pressure-sensitive electrode (113).

8. The pressure sensor according to claim 7, characterized in that Also includes: The upper cover (500) is sealed and connected to one side of the metal base (300), and the pressure-sensitive film common electrode lead pin (610), the upper plate differential electrode lead pin (620) and the upper plate pressure-sensitive electrode lead pin (630) all pass through the upper cover (500). The upper cover (500) includes: A cover cavity (510) is provided inside the upper cover (500), and the upper electrode plate (100) and the pressure-sensitive film (200) are both sealed inside the cover cavity (510); A suction needle (520) is inserted through the top of the upper cover (500) and is used to evacuate the interior of the cover cavity (510); Structural regulation (400), said structural regulation (400) comprising: A conduit (410) having an airway (430) therein for communicating with the outside; The gauge seat (420) is provided at one end of the conduit (410) and is sealed and connected to the metal base body (310). A ventilation cavity (440) is provided inside the gauge seat (420). One end of the ventilation cavity (440) is connected to the ventilation channel (430), and the other end is connected to the process hole (340).

9. The pressure sensor according to claim 7 or 8, characterized in that: Also includes: A second pressure-sensitive film common electrode conductive area (130) is provided on a side of the upper plate body (110) facing away from the pressure-sensitive film (200), one end of the second pressure-sensitive film common electrode conductive area (130) is electrically connected to the first pressure-sensitive film common electrode conductive area (240) via a pressure-sensitive film common electrode lead-out hole (116) provided on the upper plate body (110), and the other end is electrically connected to the pressure-sensitive film common electrode lead-in pin (610); An upper plate differential electrode conductive area (120) is provided on one side of the second pressure-sensitive film common electrode conductive area (130), one end of the upper plate differential electrode conductive area (120) is electrically connected to the upper plate differential electrode (112) via an upper plate differential electrode lead-out hole (115) provided on the upper plate body (110), and the other end is electrically connected to the upper plate differential electrode lead-in pin (620); The upper plate pressure-sensitive electrode conductive area (140) is provided on the other side of the second pressure-sensitive film common electrode conductive area (130); one end of the upper plate pressure-sensitive electrode conductive area (140) is electrically connected to the upper plate pressure-sensitive electrode (113) via an upper plate pressure-sensitive electrode lead-out hole (114) provided on the upper plate body (110); and the other end is electrically connected to the upper plate pressure-sensitive electrode lead-in pin (630).

10. A method for preparing a pressure sensor, characterized in that: include: An upper electrode plate (100) and a pressure-sensitive film (200) are prepared using aluminum oxide crystal material; Forming a plate gap on the upper plate (100) through a layer-by-layer peeling process; Electrodes are plated on the upper electrode plate (100) and the pressure-sensitive film (200); preparing a metal base (300); The upper electrode plate (100), the pressure-sensitive film (200) and the metal base (300) are connected by a direct bonding process; Complete the rest of the pressure sensor assembly.

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