Capacitive pressure sensor and method of manufacturing the same

Abstract

The application relates to the technical field of pressure sensors, in particular to a polymer precursor-derived ceramic capacitive pressure sensor and a preparation method thereof. The capacitive pressure sensor comprises an upper electrode plate and a lower electrode plate, the lower surface of the upper electrode plate and the upper surface of the lower electrode plate are respectively provided with corresponding micron-level array column structures, the micron-level array column structures form a microarray composite electrode, and the micron-level array column structures are connected with wires. The capacitive pressure sensor combines the corrosion resistance, high temperature resistance, high strength and other characteristics of ceramics with the high sensitivity, long service life and other characteristics of capacitors, has the advantages of ceramic and capacitor structures, and is widely applied in high-temperature extreme environments.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pressure sensors, in particular to a polymer precursor-derived ceramic capacitive pressure sensor and a preparation method thereof. BACKGROUND

[0002] As a kind of sensor most commonly used in instrument control and industrial production, pressure sensor is not only widely used in various industrial automation environments, biomedical, electronic products, Internet of Things and artificial intelligence fields, but also plays an irreplaceable role in accurately measuring pressure information in high-temperature extreme environments such as aircraft engines and nuclear reactors. It is a big problem to ensure the stability of the structure and function of the sensing material in extreme environments, so it is crucial to prepare a new type of pressure sensor material that can be used in high-temperature extreme environments.

[0003] At present, Chinese patent CN109678519A discloses a high-temperature pressure sensor based on polymer precursor ceramic, which uses the piezoresistive property of polymer precursor ceramic to prepare a piezoresistive pressure sensor. The sensor has high service temperature and long service life, but the polymer precursor ceramic resistance is also very sensitive to temperature changes. In high-temperature use, it is difficult to effectively separate the temperature signal and the pressure signal, and the measurement accuracy cannot be guaranteed. Chinese patents CN109406038A and CN109406040A respectively disclose a flat film structure SiAlCN and SiBCN wireless passive pressure sensor. The sensor uses wireless sensing technology to measure the change of pressure. The test end and the sensor end are separated. The pressure is converted into a frequency shift output. The frequency shift signal can be detected remotely. The sensor is suitable for pressure measurement in high-temperature environments, but the preparation process and subsequent processing circuit of the resonant sensor are complex.

[0004] Chinese patent CN109781312B discloses a preparation method of a capacitive pressure sensor, which improves the sensitivity of the sensor by designing an ionic gel nano-microstructure array dielectric layer. A capacitive pressure sensor with a double-sided ionic gel medium layer structure is prepared. The sensitivity of the sensor has been significantly improved, but the ionic gel used in this sensor is a high molecular material, which cannot be applied in high-temperature extreme environments, and the application temperature range is narrow, which has limitations. Chinese patent CN112362199A discloses a preparation method of a capacitive pressure sensor, which uses deposition, etching, lithography, polishing and other processes to prepare a poly-silicon elastic film and a pressure-sensing array of silicon nitride material, and a phosphorus-doped poly-silicon comb-shaped electrode on a silicon nitride substrate. By designing the electrode microstructure, the relative dielectric constant between the electrodes is changed to improve the sensitivity of the sensor. However, the sensor works in a large deflection deformation region, the linearity is limited, and the preparation process of the sensor microarray structure is complex and the cost is high, which limits its wide application.

[0005] From the current research progress, many researchers are committed to designing the micro-nano structure of the dielectric layer to improve the sensitivity of the capacitive pressure sensor, and there are few reports about designing the micro-nano structure of the electrode to improve the sensitivity of the capacitive pressure sensor. The application of micro-structure electrode to ceramic capacitive pressure sensor is less, and the regular microstructure is usually applied by photolithography, chemical etching, plasma treatment and other methods, which is complex in process and high in cost, and it is difficult to realize large-area preparation. However, a simple and low-cost preparation method cannot make the device achieve ideal performance, thereby limiting its application in practice. Therefore, the preparation of microarray electrode is a big problem in the preparation of high-sensitivity pressure sensor at present. SUMMARY

[0006] Therefore, the purpose of the present application is to provide a capacitive pressure sensor which can improve the sensitivity and linearity of the sensor while ensuring stable and efficient operation of the sensor in high-temperature extreme environment, thereby solving the technical problems of poor pressure stability, serious temperature drift effect, mutual restriction of linearity and sensitivity, and inability to consider of the existing polymer precursor ceramic pressure.

[0007] The technical scheme adopted by the present application is:

[0008] A capacitive pressure sensor comprises:

[0009] A lower plate is connected with a support fixing frame on the upper surface;

[0010] An upper plate is arranged on the support fixing frame;

[0011] An enclosed cavity is formed around the upper plate, the support fixing frame and the lower plate;

[0012] A micron-level array column structure corresponding in position is arranged on the lower surface of the upper plate and the upper surface of the lower plate, respectively, the micron-level array column structure forms a microarray composite electrode, and the micron-level array column structure is connected with a wire;

[0013] The upper plate and the lower plate are ceramic diaphragms plated with metal, and a pressure head is arranged on the upper surface of the upper plate.

[0014] The metal is one of Au and Ag or a combination of the two, and the wire is a platinum wire.

[0015] The ceramic diaphragm is one of polymer precursor converted SiBCN, SiAlCN, SiAlBCN, SiCN and SiOC ceramic or a combination thereof, the ceramic diaphragm has a side length of 3.5-8.5mm and a thickness of 0.2-1.0mm.

[0016] The single array column of the micrometer array column structure is one of a circle, a square or a combination of both, the diameter or side length of the single array column is 0.1-15 μm, the height is 0.6-75 μm, and the array column spacing is 0.1-12 μm.

[0017] The lower plate is connected with the support fixed frame to form a rectangular frame, the height of the rectangular frame is 0.1-0.6 mm, the inner side length of the rectangular frame is 1-7 mm, and the outer side length is 3.5-8.5 mm.

[0018] The micrometer array column structure is prepared by a template method, and a silicon template or a photoresist template is used.

[0019] The method for preparing a capacitive pressure sensor comprises the following steps:

[0020] 1) The liquid polymer ceramic precursor is vacuumed to remove gas and most small molecules, then a doping element precursor, a photo initiator (3-5%) is added and heated to dissolve into a precursor solution;

[0021] 2) The precursor solution obtained in 1) is poured into a silicone rubber flexible template with a microarray structure, and after light curing, the upper plate and the lower plate with a microarray structure are obtained by demolding;

[0022] 3) The upper plate and the lower plate after demolding in 2) are directly pyrolyzed to obtain a ceramic diaphragm, or soaked in a doping element precursor solution and dried, and then pyrolyzed to obtain a ceramic diaphragm containing a doping element;

[0023] 4) A metal is vacuumed and evaporated on one side of the microarray structure of the ceramic diaphragm, so that the surface of the ceramic diaphragm and the side surface of the array structure are completely covered with the metal, forming a complete and continuous upper plate composite electrode and a lower plate composite electrode;

[0024] 5) The upper plate composite electrode and the lower plate composite electrode obtained in 4) are bonded with wires, and then the upper plate composite electrode, the support fixed frame and the lower plate composite electrode are packaged together. The side plated with Au or Ag is opposite to the packaging.

[0025] In the step 1):

[0026] When the precursor is a SiCN ceramic precursor, the liquid polymer ceramic precursor is polysilazane, 3-5%wt of the initiator phenyl bis (2, 4, 6-trimethyl benzoyl) phosphine oxide is added, and stirred at 70-100 ℃ for 1-2 h to obtain a SiCN ceramic precursor solution;

[0027] When the precursor is SiAlCN ceramic, 9-11wt% aluminum sec-butyl solution is added to polysilazane, 3-5wt% initiator 819 is added, and stirring is performed at 50-90°C for 1-2h to obtain a SiAlCN ceramic precursor solution;

[0028] When the precursor is SiBCN ceramic precursor, 8-10wt% boron trichloride hexane solution is added to polysilazane, 3-5wt% initiator 819 is added, and stirring is performed at 70-100°C for 1-2h to obtain a SiBCN ceramic precursor solution;

[0029] When the precursor is SiAlBCN ceramic precursor, 8-11wt% aluminum sec-butyl solution and 6-8wt% boron trichloride hexane solution are added to polysilazane, 3-5wt% initiator 819 is added, and stirring is performed at 50-70°C for 1-2h to obtain a SiAlBCN ceramic precursor solution;

[0030] When the precursor is SiOC ceramic precursor, the liquid polymeric ceramic precursor is polysiloxane, 3-5wt% initiator 819 is added, and stirring is performed at 60-80°C for 1-2h to obtain a SiOC ceramic precursor solution.

[0031] The upper and lower plates can be directly pyrolyzed to obtain ceramic diaphragms. In specific operations, the light curing time in step 2) is 10-20min for SiCN ceramic precursor, 8-15min for SiAlCN ceramic precursor, 10-15min for SiBCN ceramic precursor, 5-15min for SiAlBCN ceramic precursor, and 5-10min for SiOC ceramic precursor.

[0032] In step (3), SiCN ceramic precursor is pyrolyzed at 800-1000°C for 3-5h to obtain SiCN ceramic diaphragm, SiAlCN ceramic precursor is pyrolyzed at 1000-1400°C for 2-4h to obtain SiAlCN ceramic diaphragm, SiBCN ceramic precursor is pyrolyzed at 1000-1200°C for 2-4h to obtain SiBCN ceramic diaphragm, SiAlBCN ceramic precursor is pyrolyzed at 900-1200°C for 3-4h to obtain SiAlBCN ceramic diaphragm, and SiOC ceramic precursor is pyrolyzed at 1000-1300°C for 2-4h to obtain SiOC ceramic diaphragm.

[0033] The upper and lower pole plates can also be soaked in a doped element precursor solution, dried, and then pyrolyzed at high temperature, for example: after photopolymerization, the SiCN ceramic precursor is soaked in a toluene solution of borane dimethyl sulfide, dried at 70-100 DEG C for 4-6h, and then pyrolyzed at 1000-1200 DEG C for 2-4h to obtain a SiBCN ceramic membrane.

[0034] The photopolymerized SiAlCN ceramic precursor is soaked in a toluene solution of borane dimethyl sulfide, dried at 70-100 DEG C for 4-6h, and then pyrolyzed at 1000-1200 DEG C for 2-4h to obtain a SiBCN ceramic membrane.

[0035] In the application: a special form of micron array column structure is designed on the surface of the composite electrode plate, the surface area of the electrode plate is increased without changing the original macro size of the electrode plate, and the effective area of the electrode is increased, so that the prepared sensor has high sensitivity and does not reduce the linearity.

[0036] The diameter or side length, height and spacing of the micron array column structure arranged on the composite electrode plate of the application have special requirements, and under specific conditions, excellent sensor sensitivity and linearity can be achieved.

[0037] The application selects polymer precursor ceramic as the sensor electrode substrate, fully utilizes the easy forming property of polymer precursor ceramic, uses a low viscosity and good fluidity liquid precursor to prepare the micron array column structure by the method of mold casting and photopolymerization, realizes the integrated forming of the micron array column structure and the substrate, and plays the excellent oxidation resistance, thermal shock resistance and creep resistance of the polymer precursor ceramic, so that the polymer precursor ceramic can work in a high temperature extreme environment.

[0038] Compared with the prior art, the application has the beneficial technical effects that:

[0039] 1. The capacitive pressure sensor can work in various temperature environments, has the advantages of stable structure, small hysteresis effect, small temperature drift effect, etc., and has higher sensitivity and shorter response time in parameter adjustment and performance control. The capacitive pressure sensor of the application combines the corrosion resistance, high temperature resistance, high strength and other characteristics of ceramics with the high sensitivity, long service life and other characteristics of capacitors, and has the advantages of ceramic and capacitor structure, and is widely used in high temperature extreme environment.

[0040] 2. Meanwhile, the application uses trichloro(1H, 1H, 2H, 2H-tridecafluoro-n-octyl) silane to coat the surface of the mold, solves the technical problem of sample adhesion to the mold, obtains a complete microarray structure, and provides a simple and low-cost preparation method.

[0041] 3. When the upper and lower electrode plates are SiBCN ceramic diaphragms, detection shows that the nonlinearity of the prepared capacitive pressure sensor is only 0.28%, the sensitivity reaches 0.147fF / kPa below 300kPa, and reaches 0.182fF / kPa in the range of 0-600kPa; in the range of 0-600kPa pressure, 200 cycles of test are carried out, the maximum and minimum output capacitances of the sensor remain basically unchanged, and the sensor has good cycle stability. Finite element simulation results show that the deflection and stress of the SiBCN ceramic electrode plate can maintain a good linear relationship in the stress range of 0-1.8MPa, and then the output capacitance value of the sensor presents a good linear relationship, thereby ensuring the linearity of the output signal of the prepared sensor. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a structure schematic diagram of the capacitive pressure sensor prepared by the application;

[0043] Figure 2 is a structure schematic diagram of the upper and lower electrode plates of the application;

[0044] Figure 3 is an SEM image of the upper and lower electrode plates with microarray structure of the application;

[0045] Figure 4 is an SEM image of the composite electrode prepared in Example 2.

[0046] Figure 5 is a pressure-capacitance curve of the SiBCN precursor ceramic pressure sensor prepared in Example 2.

[0047] Figure 6 is a linear fitting curve of the output capacitance of the SiBCN precursor ceramic pressure sensor prepared in Example 2.

[0048] Figure 7Cyclic stability of SiBCN precursor ceramic pressure sensor prepared in Example 2.

[0049] Figure 8 SEM image of SiCN precursor ceramic diaphragm with microarray structure prepared in Example 3;

[0050] Figure 9 Pressure-capacitance curve of SiCN precursor ceramic pressure sensor prepared in Example 3.

[0051] Figure 10 Linear fitting curve of output capacitance of SiCN precursor ceramic pressure sensor prepared in Example 3. DETAILED DESCRIPTION

[0052] The specific embodiments of the present application will be described below in conjunction with examples, but the following examples are only used to illustrate the present application in detail, and do not limit the scope of the present application in any way.

[0053] Example 1

[0054] The structure of the capacitive pressure sensor in the present application is shown in Figure 1 The specific structure is as follows: including an upper plate 1, a lower plate 2, and a support fixing frame 3, the support fixing frame 3 is arranged between the lower plate 2 and the upper plate 1, so that a closed cavity is formed around the upper plate 1, the support fixing frame 3 and the lower plate 2. The upper plate 1 and the lower plate 2 are ceramic diaphragms plated with metal, and the metal layers of the upper plate 1 and the lower plate 2 are arranged opposite to each other. A pressure head 4 is arranged on the upper surface of the upper plate 1.

[0055] A micron-level array column structure 6 corresponding in position is arranged on the lower surface of the upper plate 1 and the upper surface of the lower plate 2 respectively, the micron-level array column structure 6 forms a microarray composite electrode, and the micron-level array column structure 6 is connected with a lead wire 5, and the lead wire 5 is connected with an external circuit. The single array column of the micron-level array column structure is one of a circle, a square or a combination of the two, the diameter or the side length of the single array column is 0.1-15 μm, the height is 0.6-75 μm, and the array column spacing is 0.1-12 μm.

[0056] The ceramic diaphragm used to make the upper plate 1 and the lower plate 2 is one of or a combination of polymer precursor converted SiBCN, SiAlCN, SiAlBCN, SiCN, SiOC ceramic, the edge length of the ceramic diaphragm is 3.5-8.5 mm, and the thickness is 0.2-1.0 mm.

[0057] The lower plate and the support fixing frame are connected together to form a rectangular frame, the height of the support fixing frame is 0.1-0.6 mm, the inner edge length of the rectangular frame is 1-7 mm, and the outer edge length is 3.5-8.5 mm.

[0058] Example 2: Taking SiBCN precursor ceramic capacitive pressure sensor as an example, the following steps are included in the production: (1) configure photosensitive ceramic precursor: take 3 ml of polysilazane (PSN) in a round-bottom flask, under the protection of high-purity nitrogen, magnetically stir and vacuum for 30 min, then add 4 wt.% of phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (Irgacure 819), heat to 90°C and magnetically stir for 2 h to completely dissolve 819 into a precursor solution.

[0059] (2) Pour the precursor solution into a silicone rubber flexible template with a microarray structure, and cross-link and cure for 10 min, then demold to obtain an upper plate and a lower plate with complete microarray structure, with a single array column diameter of 10 μm, a height of 10 μm, and a spacing between each column of 10 μm, as shown in Figure 3 、 4 .

[0060] (3) Put the cured upper plate and lower plate in (2) into a sample bottle, add 4 ml of 2.5 mol / L borane dimethyl sulfide complex toluene solution, soak for 20 min, then take out and blow dry the surface residual borane solution with a nitrogen stream, and finally dry the sample in a vacuum drying oven at 60°C for 5 h.

[0061] (4) Put the sample reacted with borane dimethyl sulfide complex in (3) into an alumina ceramic boat and place it in a tube furnace, pyrolyze at 1000°C for 4 h under nitrogen protection to obtain a SiBCN precursor ceramic membrane.

[0062] (5) Vacuum evaporate Au on one side of the ceramic membrane microarray structure obtained in (4) to completely cover the surface of the ceramic membrane and the side surface of the array column, forming a complete and continuous upper plate composite electrode and lower plate composite electrode, as shown in Figure 5 . The size of the membrane is 5.5 x 5.5 x 0.6 mm 3 , with a total of 66049 array columns, a total electrode surface area of 42.51 mm 2 , and a total surface area without array column structure of 30.25 mm 2 , with an electrode surface area increase of 12.26 mm 2 .

[0063] (6) Connect the upper plate composite electrode and the lower plate composite electrode obtained in (5) to the external circuit using high-temperature platinum paste to bond platinum gold wires, then package the electrode-coated side opposite to each other, and use high-temperature sealing glue to bond the two electrodes supported by the alumina support frame as one, to obtain a SiBCN precursor ceramic capacitive pressure sensor, as shown in Figure 1 、 2 , 3.

[0064] The SiBCN ceramic pressure sensor in the embodiment was tested for linearity, sensitivity, and cycle stability, and the results are shown in Figs. Figure 4 , 5 , 6, 7.

[0065] It can be seen from Figs. Figure 4 that the gold electrode not only covers the surface of the ceramic substrate, but also has a complete electrode layer on the side surface of the array column, and the gold particles are in close contact and uniformly continuous, indicating that the prepared electrode layer is uniform and continuous and can provide good electrical conductivity. It can be seen from Figs. Figure 6 , 7 that the test results show that the non-linearity of the SiBCN precursor ceramic capacitive pressure sensor is only 0.28%, the sensitivity reaches 1.47 fF / kPa below 300 kPa, and reaches 1.82 fF / kPa in the range of 0-600 kPa, and on the premise of high sensitivity, the linearity is not reduced; the maximum and minimum output capacitances of the sensor remain basically unchanged in the 200-cycle test in the range of 0-600 kPa, indicating that the SiBCN precursor ceramic pressure sensor has good cycle stability.

[0066] Example 3: Taking the SiCN precursor ceramic capacitive pressure sensor as an example, the following steps are included in the production:

[0067] (1) Prepare a photosensitive ceramic precursor: take 4 ml of polysilazane (PSN) in a round-bottom flask, magnetically stir under high-purity nitrogen protection, and vacuum for 20 min, then add 4.5 wt.% of phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (Irgacure 819), heat to 95°C and magnetically stir for 2 h until 819 is completely dissolved into the precursor solution.

[0068] (2) Pour the precursor solution into a silicone rubber flexible template with a microarray structure, and cross-link and cure by light solidification for 10 min to obtain an upper electrode plate and a lower electrode plate with complete microarray structure, with a single array column diameter of 1 μm and a height of 3 μm, and a spacing of 4 μm between each cylinder.

[0069] (3) Put the cured upper electrode plate and lower electrode plate in (2) into an alumina ceramic boat and place it in a tube furnace, and pyrolyze at 1000°C for 4 h under nitrogen protection to obtain a SiCN precursor ceramic microarray film.

[0070] (4) Vacuum evaporate Au on one side of the ceramic film microarray structure obtained in (3) to completely cover the surface of the ceramic film and the side surface of the array column, forming a complete and continuous upper electrode plate composite electrode and a lower electrode plate composite electrode.

[0071] (5) The upper and lower electrode plate composite electrodes obtained in (4) are connected to the external circuit by high-temperature platinum paste and platinum gold wire, respectively, and then the electrodes are opposite to each other and encapsulated, and the two electrodes are separated by a silicon nitride support fixed frame and integrated by high-temperature sealing glue, to obtain a SiCN precursor ceramic capacitor pressure sensor.

[0072] The SEM image of the upper electrode plate composite electrode in the embodiment is shown in FIG. 8, and it can be seen from the image that the SiCN precursor ceramic micro-column array structure with a diameter of 1 μm and a height of 3 μm is prepared by demolding, and the minimum molding size of the polymer precursor ceramic reaches 1 μm. Figure 8 The pressure-capacitance curve and the linear fitting curve of the output capacitance of the obtained SiCN precursor ceramic capacitor pressure sensor are shown in FIG. 9, and it can be seen from the figure that the capacitance monotonically increases with the increase of the pressure and maintains a good linear relationship. Figure 9 、 10 The linear fitting result of FIG. 9 shows that the sensitivity of the sensor is 0.194 pF / MPa, and the full-scale nonlinear error is 0.53%, which has good sensitivity but large nonlinear error. Figure 9 Figure 10

[0073] Embodiment 4: Taking a SiAlCN precursor ceramic capacitor pressure sensor as an example, the following steps are included in the production:

[0074] (1) Prepare a photosensitive ceramic precursor: take 3 ml of polysilazane (PSN) in a round-bottom flask, add 9% wt aluminum sec-butoxide solution, and under the protection of high-purity nitrogen, 80°C magnetic stirring for 20 min, add 3.5 wt.% of phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (Irgacure 819), heat to 90°C and magnetic stirring for 1.5 h to completely dissolve 819 into a precursor solution.

[0075] (2) Pour the precursor solution into a silicone rubber flexible mold with a microarray structure, and photocure for 10 min to complete crosslinking and curing. The upper and lower electrode plates with complete microarray structure are obtained by demolding, and the single array column has a diameter of 0.1 μm and a height of 0.6 μm, and the distance between each cylinder is 0.1 μm.

[0076] (3) Put the upper and lower electrode plates obtained in (2) into an alumina ceramic boat and place it in a tube furnace, and pyrolyze at 1200°C for 3.5 h under nitrogen protection to obtain a SiAlCN ceramic diaphragm.

[0077] (4) Vacuum evaporate Au on one side of the ceramic diaphragm microarray structure obtained in (3) to completely cover the surface of the ceramic diaphragm and the side surface of the array column with Au, forming complete and continuous upper and lower electrode plate composite electrodes. The size of the diaphragm is 6.5×6.5×0.8 mm​​3 , with a total electrode surface area of 157.62 mm 2 , with a total electrode surface area of 157.62 mm 2 , with a total electrode surface area of 157.62 mm 2 .

[0078] (5) The upper and lower electrode plate composite electrodes obtained in (4) are connected to the external circuit using high-temperature platinum paste to adhere platinum gold wires, then the electrodes are packaged with the electrode-plated side opposite each other, the two electrodes are separated by a silicon nitride support fixed frame, and the high-temperature sealing glue is used to adhere them together, obtaining a SiAlCN precursor ceramic capacitive pressure sensor.

[0079] Example 5: Taking the SiAlBCN precursor ceramic capacitive pressure sensor as an example, the following steps are included in the production:

[0080] (1) Configure a photosensitive ceramic precursor: take 5 ml of polysilazane (PSN) in a round-bottom flask, add 8% wt of sec-butyl aluminum solution and 7.5% wt of boron trichloride hexane solution, under the protection of high-purity nitrogen, 60°C magnetic stirring for 30 min, add 4 wt.% of phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (Irgacure 819), heat to 70°C and magnetic stirring for 2h to completely dissolve 819 into a precursor solution.

[0081] (2) Pour the precursor solution of (1) into a silicone rubber flexible mold with a microarray structure, photocure for 10 min, complete crosslinking and curing, and demold to obtain an upper electrode plate and a lower electrode plate with complete microarray structure, with a single array column diameter of 15 μm, a height of 75 μm, and a distance between each column of 12 μm.

[0082] (3) Put the cured upper and lower electrode plates in (2) into an alumina ceramic boat and place it in a tube furnace, pyrolyze at 1100°C for 4h under nitrogen protection to obtain a SiAlBCN precursor ceramic microarray film.

[0083] (4) Vacuum evaporate Au on one side of the ceramic film microarray structure obtained in (3) to completely cover the surface of the ceramic film and the side surface of the array column, forming complete and continuous upper and lower electrode plate composite electrodes. The size of the film is 8.5x8.5x1.0mm 3 , with a total electrode surface area of 157.62 mm 2 , with a total electrode surface area of 157.62 mm 2 , with a total electrode surface area of 157.62 mm 2 .

[0084] (5) The upper and lower plate composite electrodes obtained in (4) are connected to the external circuit by high-temperature platinum paste, and then the electrodes are packaged opposite to each other, and the two electrodes are separated by a silicon nitride support fixed frame and integrated by high-temperature sealing glue, to obtain a SiAlBCN precursor ceramic capacitive pressure sensor.

[0085] Example 6: Taking a SiOC precursor ceramic capacitive pressure sensor as an example, the following steps are included in the production: (1) configuring a photosensitive ceramic precursor: taking 3 ml of polysiloxane in a round-bottom flask, under the protection of high-purity nitrogen, magnetically stirring and vacuuming for 20 min, then adding 5 wt.% of phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide (Irgacure 819), heating to 80°C and magnetically stirring for 1.5 h to completely dissolve 819 into a precursor solution.

[0086] (2) Pour the precursor solution into a silicone rubber flexible template with a microarray structure, and crosslink and cure by light solidification for 10 min to obtain an upper plate and a lower plate with complete microarray structure, with a single array column diameter of 0.2 μm, a height of 0.9 μm, and a spacing between each column of 0.3 μm.

[0087] (3) Put the upper and lower plates obtained in (2) into an alumina ceramic boat and place it in a tube furnace, and pyrolyze at 1000°C for 4 h under nitrogen protection to obtain a SiOC precursor ceramic microarray film.

[0088] (4) Vacuum evaporate Au on one side of the ceramic film microarray structure obtained in (3) to completely cover the Au on the surface of the ceramic film and the side surface of the array column, forming complete and continuous upper and lower plate composite electrodes. The size of the film is 3.5 x 3.5 x 0.2 mm 3 , with a total of 26604964 array columns, and the total electrode surface area is 20.9 mm 2 , and the total surface area without array column structure is 12.25 mm 2 , and the electrode surface area is increased by 8.65 mm 2 .

[0089] (5) The upper and lower plate composite electrodes obtained in (4) are connected to the external circuit by high-temperature platinum paste, and then the electrodes are packaged opposite to each other, and the two electrodes are separated by a silicon nitride support fixed frame and integrated by high-temperature sealing glue, to obtain a SiOC precursor ceramic capacitive pressure sensor.

[0090] In the research of the present application, the inventors found that the system of polymer precursor and the doping of different elements have different influences on the structure and performance of the pressure sensor; the array shape and spacing of the microarray also have direct influences on the performance of the pressure sensor.

[0091] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application but not to limit the present application, and other modifications or equivalent replacements made by those skilled in the art to the technical solutions of the present application should be covered in the scope of the claims of the present application as long as they do not deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A capacitive pressure sensor, characterized by The application relates to a microarray composite electrode, which comprises the following parts: a lower plate, wherein a supporting fixed frame is connected to the upper surface of the lower plate; an upper plate, wherein the upper plate is arranged on the supporting fixed frame; an enclosed cavity is formed around the upper plate, the supporting fixed frame and the lower plate; micron-level array column structures are arranged on the lower surface of the upper plate and the upper surface of the lower plate respectively, the micron-level array column structures form a microarray composite electrode, and the micron-level array column structures are connected with wires; the upper plate and the lower plate are ceramic diaphragms plated with metal, a pressure head is arranged on the upper surface of the upper plate, the ceramic diaphragm is one of SiBCN, SiAlCN, SiAlBCN, SiCN and SiOC ceramics or a combination thereof prepared through polymer precursor transformation.

2. The capacitive pressure sensor of claim 1, wherein: The ceramic diaphragm has a side length of 3.5-8.5 mm and a thickness of 0.2-1.0 mm.

3. The capacitive pressure sensor of claim 1, wherein: The single array column of the micron-level array column structure is one of a circle and a square or a combination of the two, the diameter or side length of the single array column is 0.1-15 mu m, the height of the single array column is 0.6-75 mu m, and the array column spacing is 0.1-12 mu m.

4. The capacitive pressure sensor of claim 1, wherein: The lower plate and the supporting fixed frame are connected together to form a rectangular frame, the height of the rectangular frame is 0.1-0.6 mm, the inner side length of the rectangular frame is 1-7 mm, and the outer side length of the rectangular frame is 3.5-8.5 mm.

5. The capacitive pressure sensor of claim 1, wherein: The micron-level array column structure is prepared through a template method, and a silicon template or a photoresist template is adopted.

6. A method of manufacturing the capacitive pressure sensor of claim 1, characterized in that, The application further discloses a preparation method of the microarray composite electrode, which comprises the following steps: 1) vacuumizing a liquid polymer ceramic precursor, then adding a doping element precursor and a photoinitiator, and dissolving the liquid polymer ceramic precursor to obtain a precursor solution by heating; 2) pouring the precursor solution obtained in the step 1) into a silicone rubber flexible template with a microarray structure, carrying out light solidification, and then demolding to obtain an upper plate and a lower plate with a microarray structure; 3) directly pyrolyzing the upper plate and the lower plate after demolding in the step 2) to obtain a ceramic diaphragm, or soaking the upper plate and the lower plate after demolding in the step 2) in a doping element precursor solution, drying, and then pyrolyzing to obtain a ceramic diaphragm containing a doping element; 4) vacuum depositing metal on one side of the microarray structure of the ceramic diaphragm in the step 3) so that the surface of the ceramic diaphragm and the side surface of the array structure are completely covered with metal, and complete and continuous upper plate composite electrodes and lower plate composite electrodes are formed; 5) bonding wires to the upper plate composite electrodes and the lower plate composite electrodes obtained in the step 4), and then packaging the upper plate composite electrodes, the supporting fixed frame and the lower plate composite electrodes together.

7. The method of claim 6, wherein: In the step 1), when the precursor is a SiCN ceramic precursor, the liquid polymer ceramic precursor is polysilazane, 3-5 wt% of an initiator phenyl bis (2, 4, 6-trimethylbenzoyl) phosphine oxide is added, and stirring is carried out at 70-100 DEG C for 1-2 h to obtain a SiCN ceramic precursor solution; when the precursor is a SiAlCN ceramic, 9-11 wt% of an aluminum sec-butoxide solution is added to polysilazane, 3-5 wt% of an initiator 819 is added, and stirring is carried out at 50-90 DEG C for 1-2 h to obtain a SiAlCN ceramic precursor solution; when the precursor is a SiBCN ceramic precursor, 8-10 wt% of a boron trichloride hexane solution is added to polysilazane, 3-5 wt% of an initiator 819 is added, and stirring is carried out at 70-100 DEG C for 1-2 h to obtain a SiBCN ceramic precursor solution. When the precursor is SiAlBCN ceramic precursor, 8-11wt% aluminum sec-butyl alcohol solution and 6-8wt% boron trichloride hexane solution are added to the polysilazane, 3-5wt% initiator 819 is added, and stirring is carried out at 50-70℃ for 1-2h to obtain a SiAlBCN ceramic precursor solution; When the precursor is SiOC ceramic precursor, the liquid polymer ceramic precursor is polysiloxane, 3-5wt% initiator 819 is added, and stirring is carried out at 60-80℃ for 1-2h to obtain a SiOC ceramic precursor solution.

8. The method of claim 6, wherein: The light curing time in the step 2) is 10-20min for SiCN ceramic precursor, 8-15min for SiAlCN ceramic precursor, 10-15min for SiBCN ceramic precursor, 5-15min for SiAlBCN ceramic precursor, and 5-10min for SiOC ceramic precursor.

9. The method of claim 6, wherein: In the step (3), the SiCN ceramic precursor is pyrolyzed at 800-1000℃ for 3-5h to obtain a SiCN ceramic membrane; the SiAlCN ceramic precursor is pyrolyzed at 1000-1400℃ for 2-4h to obtain a SiAlCN ceramic membrane; the SiBCN ceramic precursor is pyrolyzed at 1000-1200℃ for 2-4h to obtain a SiBCN ceramic membrane; the SiAlBCN ceramic precursor is pyrolyzed at 900-1200℃ for 3-4h to obtain a SiAlBCN ceramic membrane; and the SiOC ceramic precursor is pyrolyzed at 1000-1300℃ for 2-4h to obtain a SiOC ceramic membrane.

10. The method of claim 6, wherein: The SiCN ceramic precursor after light curing is soaked in a toluene solution of borane dimethyl sulfide, and a SiBCN ceramic membrane is obtained after drying and pyrolysis at 1000-1200℃ for 2-4h; The SiAlCN ceramic precursor after light curing is soaked in a toluene solution of borane dimethyl sulfide, and a SiAlBCN ceramic membrane is obtained after drying and pyrolysis at 900-1200℃ for 3-4h.

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