CN116519174A - A kind of capacitive pressure sensor and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of pressure sensors, in particular to a polymer precursor converted ceramic capacitive pressure sensor and a preparation method thereof. The capacitive pressure sensor includes an upper plate and a lower plate, the lower surface of the upper plate and the upper surface of the lower plate are respectively provided with corresponding micron-scale array column structures, and the micron-scale array column structure forms a microarray composite electrode , the micron-scale array column structure is connected with wires. The capacitive pressure sensor of the present invention combines the characteristics of corrosion resistance, high temperature resistance, and high strength of ceramics with the characteristics of high sensitivity and long life of capacitance, and has the advantages of both ceramic and capacitance structures, and is widely used in extreme high temperature environments. application.

Description

A kind of capacitive pressure sensor and preparation method thereof

technical field

The invention relates to the technical field of pressure sensors, in particular to a polymer precursor converted ceramic capacitive pressure sensor and a preparation method thereof.

Background technique

As the most commonly used sensor in instrumentation control and industrial production, pressure sensors are not only widely used in various industrial automation environments, biomedical, electronic products, Internet of Things, and artificial intelligence, but also accurately measure aeroengines, nuclear reactors, etc. It plays an irreplaceable role in the pressure information under high temperature extreme environment. Ensuring the stability of the structure and function of sensing materials in extreme environments is a big problem, so it is very important to prepare new pressure sensor materials that can be used in high temperature and extreme environments.

At present, Chinese patent CN109678519A discloses a high-temperature pressure sensor based on polymer precursor ceramics. The piezoresistive pressure sensor is prepared by using the piezoresistive properties of polymer precursor ceramics. The sensor has a high temperature and a long service life, but due to The polymer precursor ceramic resistance is also very sensitive to temperature changes. When used at high temperatures, 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 membrane structure SiAlCN and SiBCN wireless passive pressure sensor. The sensor uses wireless sensing technology to measure the change of pressure. The shift signal can be detected at a distance, and the sensor is suitable for pressure measurement in a high-temperature environment, but the preparation process and subsequent processing circuit of the resonant sensor are complicated.

Chinese patent CN109781312B discloses a preparation method of a capacitive pressure sensor. By designing the ion gel nano-microstructure array dielectric layer to improve the sensitivity of the sensor, a capacitive pressure sensor with a double-sided ion gel dielectric layer structure is prepared. The sensitivity of the sensor has been significantly improved, but the ion gel used in the sensor is a polymer material, which cannot be used 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 processes such as deposition, etching, photolithography, and polishing to prepare an elastic film made of polysilicon and a pressure-sensitive array made of silicon nitride, and Phosphorus-doped polysilicon comb-shaped electrodes were prepared on silicon substrates. The sensitivity of the sensor was improved by designing the electrode microstructure and changing the relative dielectric constant between the plates. The preparation process of the sensor microarray structure is complicated and the cost is high, which limits its wide application.

Judging from the current research progress, many researchers are committed to designing dielectric layer micro-nano structures to improve the sensitivity of capacitive pressure sensors, but there are few reports on designing electrode micro-nano structures to improve the sensitivity of capacitive pressure sensors. There are fewer studies on ceramic capacitive pressure sensors, and the regular microstructure is usually applied by photolithography, chemical etching, plasma treatment and other methods. The process is complicated and the cost is high, and it is difficult to achieve large-scale preparation. However, the low-cost preparation method cannot make the device achieve the ideal performance, thus limiting its practical application. Therefore, the preparation of microarray electrodes is a major problem in the preparation of high-sensitivity pressure sensors.

Contents of the invention

In view of this, the purpose of the present invention is to provide a capacitive pressure sensor, while improving the sensitivity and linearity of the sensor, it can ensure the stable and efficient operation of the sensor in the extreme environment of high temperature, so as to solve the pressure problem of the existing polymer precursor ceramics. Poor stability, serious temperature drift effect, mutual restriction of linearity and sensitivity, and technical problems that cannot be taken into account. At the same time, the invention also provides a preparation method of the capacitive pressure sensor.

The technical scheme adopted in the present invention is:

A capacitive pressure sensor comprising:

The lower plate is connected with a supporting and fixing frame on the upper surface;

The upper pole plate is arranged on the supporting fixed frame;

A closed cavity is formed around the upper pole plate, the supporting frame and the lower pole plate;

The lower surface of the upper plate and the upper surface of the lower plate are respectively provided with corresponding micron-scale array column structures, the micron-scale array column structure forms a micro-array composite electrode, and the micron-scale array column structure is connected with wires;

The upper pole plate and the lower pole plate are metal-plated ceramic diaphragms, and a pressure head is arranged on the upper surface of the upper pole plate.

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

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

The single array column of the micron-scale array column structure is one of circular and square or a combination of both, the diameter or side length of a single array column is 0.1-15 μm, the height is 0.6-75 μm, and the spacing between array columns is 0.1 -12 μm.

The lower pole plate is connected with the supporting 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.

The micron-scale array column structure is prepared by a template method, and the template used is a silicon template or a photoresist template. (The silicon template and photoresist template are silicon templates and photoresist templates utilizing polymer microsphere technology, or silicon templates prepared by wet silicon etching using polymer microsphere technology.)

A method for preparing a capacitive pressure sensor, comprising the following steps:

1) Vacuumize the liquid polymer ceramic precursor to remove gas and most of the small molecules, then add the doping element precursor and photoinitiator (3-5%) and heat up to dissolve to form a precursor solution;

2) Pouring the precursor solution obtained in 1) into a silicone rubber flexible template with a microarray structure, and demoulding after light curing to obtain an upper plate and a lower plate with a microarray structure;

3) Pyrolyzing the upper plate and the lower plate directly after demoulding to obtain a ceramic diaphragm, or soaking the dopant element precursor solution and drying it and then pyrolyzing it to obtain a ceramic diaphragm containing a dopant element;

4) Vacuum-evaporate metal on one side of the ceramic diaphragm microarray structure in 3), so that the surface of the ceramic diaphragm and the side surface of the array structure are completely covered with metal, forming a complete and continuous upper plate composite electrode and lower plate composite electrode ;

5) Bonding wires to the composite electrode on the upper plate and the composite electrode on the lower plate obtained in 4), and then packaging the composite electrode on the upper plate, the supporting frame and the composite electrode on the lower plate together. Keep the Au or Ag plated side facing the package.

In the step 1):

When the precursor is a SiCN ceramic precursor, the liquid polymer ceramic precursor is polysilazane, adding 3-5%wt initiator phenyl bis(2,4,6-trimethylbenzoyl) Phosphine oxide, stirred at 70-100°C for 1-2h to obtain SiCN ceramic precursor solution;

When the precursor is SiAlCN ceramics, add 9-11%wt aluminum sec-butoxide solution to polysilazane, add 3-5%wt initiator 819, and stir at 50-90°C for 1-2h to obtain a SiAlCN ceramic precursor body solution;

When the precursor is a SiBCN ceramic precursor, add 8-10%wt boron trichloride hexane solution to polysilazane, add 3-5%wt initiator 819, stir at 70-100°C for 1-2h, Obtain SiBCN ceramic precursor solution;

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

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

The upper plate and the lower plate can be directly pyrolyzed at high temperature to obtain a ceramic diaphragm. During the specific operation: the light curing time in the step 2) is 10-20min for the SiCN ceramic precursor; 8-15min for the SiAlCN ceramic precursor; 8-15min for the SiBCN ceramic The precursor is 10-15min; the SiAlBCN ceramic precursor is 5-15min; the SiOC ceramic precursor is 5-10min.

In the step (3), the SiCN ceramic precursor is cracked at 800-1000°C for 3-5h to obtain a SiCN ceramic diaphragm; the SiAlCN ceramic precursor is cracked at 1000-1400°C for 2-4h to obtain a SiAlCN ceramic diaphragm; the SiBCN ceramic precursor is 1000-1200 Cracking at ℃ for 2-4h to obtain SiBCN ceramic diaphragm; SiAlBCN ceramic precursor at 900-1200℃ for 3-4h to obtain SiAlBCN ceramic diaphragm; SiOC ceramic precursor at 1000-1300℃ for 2-4h to obtain SiOC ceramic diaphragm.

The upper plate and the lower plate can also be soaked in the dopant element precursor solution and then dried at high temperature. Cracking at ℃ for 2-4h to obtain a SiBCN ceramic diaphragm. The specific operation process is: the SiCN ceramic precursor after photocuring is placed in 2-10mL of 1-3mol/L borane dimethyl sulfide toluene solution for 20-60min, then dried at 70-100°C for 4-6h, and finally Crack at 1000-1200°C for 2-4 hours to obtain SiBCN ceramic diaphragm;

The photocured SiAlCN ceramic precursor is immersed in a toluene solution of borane dimethyl sulfide, and after drying, it is cracked at 900-1200° C. for 3-4 hours to obtain a SiAlBCN ceramic diaphragm. The specific operation process is: soak the SiAlCN ceramic precursor after photocuring in 5-10mL of 1-3mol/L borane dimethyl sulfide toluene solution for 20-60min, then dry at 70-100℃ for 1-2h, Finally, crack at 900-1200°C for 3-4 hours to obtain a SiAlBCN ceramic diaphragm.

In the present invention: a special micron-scale array column structure is designed on the surface of the composite electrode plate, and the surface area of the electrode plate is increased without changing the original macroscopic size of the electrode plate, thereby increasing the effective area of the electrode, so that the The prepared sensor has high sensitivity without reducing its linearity.

The present invention has special requirements on the diameter, side length, height and spacing of the micron-scale array column structure set on the composite electrode plate, and only under certain conditions can the excellent sensor sensitivity and linearity be brought into play.

The present invention selects the polymer precursor ceramics as the sensor electrode substrate, fully utilizes the easy formability of the polymer precursor ceramics, and uses a liquid precursor with low viscosity and good fluidity to perform template casting and photocuring to prepare micron-scale arrays The column structure realizes the integrated molding of the micron-scale array column structure and the substrate, and exerts the excellent oxidation resistance, thermal shock resistance and creep resistance of the polymer precursor ceramics, enabling it to work in extreme high temperature environments.

Compared with the prior art, the beneficial technical effect of the present invention is:

1. The capacitive pressure sensor can work in a variety of temperature environments. It has the advantages of stable structure, small hysteresis effect, and small temperature drift effect. It has more advantages in parameter adjustment and performance regulation, and has higher sensitivity and shorter time. Response time. The capacitive pressure sensor of the present invention combines the characteristics of corrosion resistance, high temperature resistance, and high strength of ceramics with the characteristics of high sensitivity and long life of capacitance, and has the advantages of both ceramic and capacitance structures, and is widely used in extreme high temperature environments. application.

2. At the same time, the present invention utilizes trichloro (1H, 1H, 2H, 2H-tridecafluoro-n-octyl) silane to coat the mold surface, solves the technical problem of sample and mold adhesion, obtains a complete microarray structure, and provides A simple and low-cost preparation method.

3. When the upper plate and the lower plate are SiBCN ceramic diaphragms, the test shows that the nonlinearity of the prepared capacitive pressure sensor is only 0.28%, and its sensitivity reaches 0.147fF/kPa below 300kPa. It reaches 0.182fF/kPa in the range of 600kPa; 200 cycle tests are carried out in the pressure range of 0-600kPa, the maximum and minimum output capacitance of the sensor basically remains unchanged, and it has good cycle stability. The finite element simulation results show that the deflection and stress of the SiBCN ceramic plate can maintain a good linear relationship within the stress range of 0-1.8MPa, and the output capacitance value of the sensor shows a good linear relationship, which ensures the linearity of the output signal of the prepared sensor Spend.

Description of drawings

Fig. 1 is the structural representation that the present invention makes capacitive pressure sensor;

Fig. 2 is the structural representation of upper pole plate and lower pole plate of the present invention;

Fig. 3 is the SEM figure of the upper pole plate and the lower pole plate of band microarray structure of the present invention;

FIG. 4 is a SEM image of the composite electrode prepared in Example 2.

5 is the pressure-capacitance curve of the SiBCN precursor ceramic pressure sensor prepared in Example 2.

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

Fig. 7 is the cycle stability performance of the SiBCN precursor ceramic pressure sensor prepared in Example 2.

Fig. 8 is the SEM picture of the SiCN precursor ceramic diaphragm with microarray structure prepared in embodiment 3;

9 is a pressure-capacitance curve of the SiCN precursor ceramic pressure sensor prepared in Example 3.

10 is a linear fitting curve of the output capacitance of the SiCN precursor ceramic pressure sensor prepared in Example 3.

Detailed ways

The specific implementation of the present invention will be described below in conjunction with the examples, but the following examples are only used to describe the present invention in detail, and do not limit the scope of the present invention in any way.

Example 1

The structure of the capacitive pressure sensor among the present invention is as shown in Figure 1, and concrete structure is such: comprise upper pole plate 1, lower pole plate 2, support fixed frame 3, support fixed frame 3 is arranged on lower pole plate 2 and upper pole plate Between the pole plates 1, a closed cavity is formed around the upper pole plate 1, the supporting and fixing frame 3 and the lower pole plate 2. The upper pole plate 1 and the lower pole plate 2 are metal-plated ceramic diaphragms, the metal layers of the upper pole plate 1 and the lower pole plate 2 are arranged oppositely, and a pressure head 4 is arranged on the upper surface of the upper pole plate 1 .

The lower surface of the upper plate 1 and the upper surface of the lower plate 2 are respectively provided with corresponding micron-scale array column structures 6, the micron-scale array column structures 6 form a micro-array composite electrode, and the micron-scale array column structures 6 are connected with The wire 5 is connected to the external circuit. The single array column of the micron-scale array column structure is one of circular and square or a combination of both. The diameter or side length of a 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 .

The ceramic diaphragm used to make the upper plate 1 and the lower plate 2 is one or a combination of polymer precursors transformed into SiBCN, SiAlCN, SiAlBCN, SiCN, and SiOC ceramics. The side length of the ceramic diaphragm is 3.5-8.5 mm, the thickness is 0.2-1.0mm.

The lower pole plate is connected with the support fixed frame to form a rectangular frame, the height of the support fixed 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.

Embodiment 2: Taking the SiBCN precursor ceramic capacitive pressure sensor as an example, the following steps are included in the production: (1) configure the photosensitive ceramic precursor: get 3ml polysilazane (PSN) in a round bottom flask, and place it in a high-purity Under nitrogen protection, stir magnetically and vacuumize for 30min, then add 4wt.% of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure819), raise the temperature to 90°C and stir magnetically for 2h to 819°C Dissolve completely to become a precursor solution.

(2) Pouring the precursor solution into the silicone rubber flexible template with the microarray structure, light-curing for 10 minutes, completing cross-linking and curing, demoulding to obtain the upper and lower plates with a complete microarray structure, and the diameter of a single array column 10μm, height 10μm, each cylinder spacing 10μm, as shown in Figure 3 and 4.

(3) Put the cured upper plate and lower plate in (2) into the sample bottle, add 4ml 2.5mol/L borane dimethyl sulfide complex toluene solution, take it out after soaking for 20min, and blow it with nitrogen The borane solution was blown dry on the surface, and finally the sample was dried in a vacuum oven at 60°C for 5 hours.

(4) Put the sample reacted with the borane dimethyl sulfide complex in (3) into an alumina porcelain boat, place it in a tubular atmosphere furnace, and crack it at 1000°C for 4 hours under the protection of nitrogen to obtain the SiBCN precursor body ceramic diaphragm.

(5) One side of the ceramic diaphragm microarray structure obtained in (4) is vacuum-evaporated Au, so that the surface of the ceramic diaphragm and the side surface of the array column are completely covered with Au, forming a complete and continuous composite electrode of the upper plate and the lower plate. Plate composite electrode, as shown in Figure 5. The size of the diaphragm is 5.5×5.5×0.6mm ³ , there are 66049 array columns in total, the total surface area of the electrodes is 42.51mm ² , the total surface area of the non-array column structure is 30.25mm ² , and the electrode surface area increases by 12.26mm ² .

(6) Connect the upper plate composite electrode and the lower plate composite electrode obtained in (5) to an external circuit by using high-temperature platinum paste to bond platinum wires, and then package the electrode-plated side oppositely, and the two electrodes are supported by alumina The fixed frames are separated, and the high-temperature sealant is used to bond them together to obtain a SiBCN precursor ceramic capacitive pressure sensor, as shown in Figures 1, 2, and 3.

The linearity, sensitivity and cycle stability of the SiBCN ceramic pressure sensor in the embodiment were tested, and the results are shown in Figures 4, 5, 6 and 7.

It can be seen from 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. The contact between the gold particles is close and continuous, which shows that the prepared electrode layer is uniform and continuous, which can provide good conductivity. As can be seen from Figures 6 and 7, the test results show that the nonlinearity of the SiBCN precursor ceramic capacitive pressure sensor is only 0.28%, and its sensitivity reaches 1.47fF/kPa below 300kPa, and 1.82fF/kPa in the range of 0-600kPa. kPa, under the premise of high sensitivity, without reducing its linearity; the pressure is tested 200 times in the range of 0-600kPa, and the maximum and minimum output capacitance of the sensor remain basically unchanged, indicating that the SiBCN precursor ceramic pressure sensor has Good cycle stability.

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

(1) Configure the photosensitive ceramic precursor: take 4ml polysilazane (PSN) in a round bottom flask, under the protection of high-purity nitrogen, magnetically stir and vacuumize for 20min, then add 4.5wt.% phenylbis(2 , 4,6-trimethylbenzoyl) phosphine oxide (Irgacure 819), heated to 95°C and magnetically stirred for 2h until 819 was completely dissolved to become a precursor solution.

(2) Pouring the precursor solution into the silicone rubber flexible template with the microarray structure, light-curing for 10 minutes, completing cross-linking and curing, demoulding to obtain the upper and lower plates with a complete microarray structure, and the diameter of a single array column 1μm, 3μm height, 4μm spacing between each column.

(3) Put the upper plate and the lower plate cured in (2) into an alumina ceramic boat, place them in a tubular atmosphere furnace, and crack them at 1000°C for 4 hours under the protection of nitrogen to obtain a SiCN precursor ceramic microarray Diaphragm.

(4) One side of the ceramic diaphragm microarray structure obtained in (3) is vacuum-evaporated Au, so that the surface of the ceramic diaphragm and the side surface of the array column are completely covered with Au, forming a complete and continuous composite electrode of the upper plate and the lower plate. Plate composite electrodes.

(5) The upper plate composite electrode and the lower plate composite electrode obtained in (4) are respectively connected to an external circuit by using high-temperature platinum paste to bond platinum wires, and then the electrode-plated side is relatively packaged, and the two electrodes are made of silicon nitride. The supporting and fixing frames are separated, and the spaces are bonded together with high-temperature sealant to obtain a SiCN precursor ceramic capacitive pressure sensor.

The SEM image of the composite electrode on the upper plate in this example is shown in Figure 8. It can be seen from Figure 8 that a SiCN precursor ceramic microcolumn array structure with a diameter of 1 μm and a height of 3 μm was prepared by demolding, and the polymer precursor ceramics had the smallest molding The size reaches 1 μm. The pressure-capacitance curve and the linear fitting curve of the output capacitance of the obtained SiCN precursor ceramic capacitive pressure sensor are shown in Figures 9 and 10. It can be seen from Figure 9 that the capacitance increases monotonously with the increase of pressure and maintains a relatively good linear relationship. The linear fitting results in Figure 10 show that the sensitivity of the sensor is 0.194pF/MPa, and the full-scale nonlinear error is 0.53%. The sensitivity is good but the nonlinear error is large.

Embodiment 4: Taking the SiAlCN precursor ceramic capacitive pressure sensor as an example, the following steps are included in the production:

(1) Configure the photosensitive ceramic precursor: take 3ml polysilazane (PSN) in a round bottom flask, add 9%wt aluminum sec-butoxide solution, under the protection of high-purity nitrogen, stir magnetically at 80°C for 20min, add 3.5wt .% of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819), heated to 90°C and magnetically stirred for 1.5h until 819 was completely dissolved to become a precursor solution.

(2) Pouring the precursor solution into the silicone rubber flexible template with the microarray structure, light-curing for 10 minutes, completing cross-linking and curing, demoulding to obtain the upper and lower plates with a complete microarray structure, and the diameter of a single array column 0.1μm, height 0.6μm, spacing between each column is 0.1μm.

(3) Put the upper plate and the lower plate obtained in (2) into an alumina ceramic boat, place them in a tubular atmosphere furnace, and crack them at 1200°C for 3.5 hours under the protection of nitrogen to obtain a SiAlCN precursor ceramic film piece.

(4) One side of the ceramic diaphragm microarray structure obtained in (3) is vacuum-evaporated Au, so that the surface of the ceramic diaphragm and the side surface of the array column are completely covered with Au, forming a complete and continuous composite electrode of the upper plate and the lower plate. Plate composite electrodes. The size of the diaphragm is 6.5×6.5×0.8mm ³ , there are 1037290849 array columns in total, the total surface area of the electrode is 157.62mm ² , the total surface area of the non-array column structure is 42.25mm ² , and the electrode surface area increases by 115.37mm ² .

(5) The upper plate composite electrode and the lower plate composite electrode obtained in (4) are respectively connected to an external circuit by using high-temperature platinum paste to bond platinum wires, and then the electrode-plated side is relatively packaged, and the two electrodes are made of silicon nitride. The supporting and fixing frames are separated, and the spaces are bonded together with high-temperature sealant to obtain a SiAlCN precursor ceramic capacitive pressure sensor.

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

(1) Configure the photosensitive ceramic precursor: take 5ml polysilazane (PSN) in a round bottom flask, add 8%wt aluminum sec-butoxide solution and 7.5%wt boron trichloride hexane solution, under the protection of high-purity nitrogen Stir magnetically at 60°C for 30min, add 4wt.% of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819), raise the temperature to 70°C and stir magnetically for 2h until 819 is completely dissolved and becomes precursor solution.

(2) The precursor solution of (1) was poured into the silicone rubber flexible template with the microarray structure, light-cured for 10 minutes, the cross-linking and curing were completed, and the upper and lower plates with the complete microarray structure were obtained by demoulding. The diameter of a single array column is 15 μm, the height is 75 μm, and the distance between each column is 12 μm.

(3) Put the upper plate and the lower plate cured in (2) into an alumina ceramic boat, place them in a tubular atmosphere furnace, and crack them at 1100°C for 4 hours under the protection of nitrogen to obtain a SiAlBCN precursor ceramic microarray Diaphragm.

(4) Vacuum-deposit Au on one side of the ceramic diaphragm microarray structure obtained in (3), so that the surface of the ceramic diaphragm and the side surface of the array column are completely covered with Au, forming a complete and continuous upper plate composite electrode and The lower plate composite electrode. The size of the diaphragm is 8.5×8.5×1.0mm ³ , there are 112225 array columns in total, the total electrode surface area is 306.85mm ² , the total surface area of the non-array column structure is 72.25mm ² , and the electrode surface area increases by 234.6mm ² .

(5) The upper plate composite electrode and the lower plate composite electrode obtained in (4) are respectively connected to an external circuit by using high-temperature platinum paste to bond platinum wires, and then the electrode-plated side is relatively packaged, and the two electrodes are made of silicon nitride. The supporting and fixing frames are separated, and the spaces are bonded together with high-temperature sealant to obtain a SiAlBCN precursor ceramic capacitive pressure sensor.

Embodiment 6: Taking the SiOC precursor ceramic capacitive pressure sensor as an example, the following steps are included in the production: (1) Configure the photosensitive ceramic precursor: take 3ml of polysiloxane in a round bottom flask, under the protection of high-purity nitrogen , magnetically stirred and vacuumed for 20min, then added 5wt.% of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819), heated to 80°C and magnetically stirred for 1.5h to 819 completely Dissolved into a precursor solution.

(2) Pouring the precursor solution into the silicone rubber flexible template with the microarray structure, light-curing for 10 minutes, completing cross-linking and curing, demoulding to obtain the upper and lower plates with a complete microarray structure, and the diameter of a single array column 0.2μm, height 0.9μm, spacing between each cylinder 0.3μm.

(3) Put the upper plate and the lower plate obtained in (2) into an alumina porcelain boat, place them in a tube-type atmosphere furnace, and crack them at 1000°C for 4 hours under the protection of nitrogen to obtain a SiOC precursor ceramic microarray film piece.

(4) Vacuum-deposit Au on one side of the ceramic diaphragm microarray structure obtained in (3), so that the surface of the ceramic diaphragm and the side surface of the array column are completely covered with Au, forming a complete and continuous upper plate composite electrode and The lower plate composite electrode. The size of the diaphragm is 3.5×3.5×0.2mm ³ , there are 26604964 array columns in total, the total electrode surface area is 20.9mm ² , the total surface area of the non-array column structure is 12.25mm ² , and the electrode surface area increases by 8.65mm ² .

(5) The upper plate composite electrode and the lower plate composite electrode obtained in (4) are respectively connected to an external circuit by using high-temperature platinum paste to bond platinum wires, and then the electrode-plated side is relatively packaged, and the two electrodes are made of silicon nitride. The supporting and fixing frames are separated, and the spaces are bonded together with high-temperature sealant to obtain a SiOC precursor ceramic capacitive pressure sensor.

In the research of the present invention, the inventors found that: the system of the polymer precursor and the doping of different elements have different effects on the structure and performance of the pressure sensor; the array shape and spacing of the microarray also have a direct impact on the performance of the pressure sensor. Impact.

Finally, it is noted that the above embodiments are only used to illustrate the technical solution of the present invention and not to limit it. Those of ordinary skill in the art may make other modifications or equivalent replacements to the technical solution of the present invention, as long as they do not depart from the spirit and spirit of the technical solution of the present invention. All should be included in the scope of the claims of the present invention.

Claims (10)

1. A capacitive pressure sensor, comprising:

the upper surface of the lower polar plate is connected with a supporting and fixing frame;

the upper polar plate is arranged on the supporting and fixing frame;

a closed cavity is formed among the upper polar plate, the supporting and fixing frame and the lower polar plate in a surrounding manner;

the lower surface of the upper polar plate and the upper surface of the lower polar plate are respectively provided with a micron-sized array column structure corresponding to the position, the micron-sized array column structure forms a micro-array composite electrode, and the micron-sized array column structure is connected with a wire;

the upper polar plate and the lower polar plate are ceramic membranes plated with metal, and a pressure head is arranged on the upper surface of the upper polar plate.

2. The capacitive pressure sensor of claim 1, wherein: the ceramic membrane is one or a combination of SiBCN, siAlCN, siAlBCN, siCN, siOC ceramic converted by a polymer precursor, the side length of the ceramic membrane is 3.5-8.5mm, and the thickness of the ceramic membrane is 0.2-1.0mm.

3. The capacitive pressure sensor of claim 1, wherein: the single array column of the micron-sized array column structure is one or the combination of a round column and a square column, the diameter or the side length of the single array column is 0.1-15 mu m, the height 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 polar plate and the supporting and fixing frame are connected together to form a rectangular frame, the height of the rectangular frame is 0.1-0.6mm, the inner side length of the rectangular frame is 1-7mm, and the outer side length of the rectangular frame is 3.5-8.5mm.

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

6. A method of making a capacitive pressure sensor according to claim 1, comprising the steps of:

1) Vacuumizing the liquid polymer ceramic precursor, adding the doping element precursor and the photoinitiator, and heating to dissolve the doping element precursor and the photoinitiator to form a precursor solution;

2) Pouring the precursor solution obtained in the step 1) into a silicon rubber flexible template with a microarray structure, and demoulding after light curing to obtain an upper polar plate and a lower polar plate with the microarray structure;

3) Directly high-temperature cracking the upper polar plate and the lower polar plate after demolding of the step 2) to obtain a ceramic membrane, or soaking the doping element precursor solution, drying and then high-temperature cracking to obtain the ceramic membrane containing the doping element;

4) Vacuum evaporating metal on one side of the ceramic membrane microarray structure to ensure that the surface of the ceramic membrane and the side surface of the array structure are completely covered with metal to form a complete and continuous upper polar plate composite electrode and a complete and continuous lower polar plate composite electrode;

5) Bonding wires with the upper and lower electrode plates obtained in the step 4), and packaging the upper electrode plate, the support fixing frame and the lower electrode plate.

7. The method of manufacturing according to claim 6, wherein: in the step 1), when the precursor is SiCN ceramic precursor, the liquid polymer ceramic precursor is polysilazane, 3-5 wt% of initiator phenyl bis (2, 4, 6-trimethylbenzoyl) phosphine oxide is added, and the mixture is stirred for 1-2 hours at 70-100 ℃ to obtain SiCN ceramic precursor solution;

when the precursor is SiAlCN ceramic, adding 9-11 wt% of aluminum sec-butoxide solution into polysilazane, adding 3-5 wt% of initiator 819, and stirring at 50-90 ℃ for 1-2h to obtain SiAlCN ceramic precursor solution; when the precursor is SiBCN ceramic precursor, 8-10 wt% of boron trichloride hexane solution is added into polysilazane, 3-5 wt% of initiator 819 is added, and stirring is carried out at 70-100 ℃ for 1-2h, so as to obtain SiBCN ceramic precursor solution;

when the precursor is SiAlBCN ceramic precursor, adding 8-11 wt% of sec-butyl alcohol aluminum solution and 6-8 wt% of boron trichloride hexane solution into polysilazane, adding 3-5 wt% of initiator 819, and stirring at 50-70 ℃ for 1-2 hours to obtain SiAlBCN ceramic precursor solution;

when the precursor is SiOC ceramic precursor, the liquid polymer ceramic precursor is polysiloxane, 3-5 wt% of initiator 819 is added, and stirring is carried out at 60-80 ℃ for 1-2h, so that SiOC ceramic precursor solution can be obtained.

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

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

10. The method of manufacturing according to claim 6, wherein: soaking the SiCN ceramic precursor after light fixation in toluene solution of borane dimethyl sulfide, drying, and then cracking for 2-4 hours at 1000-1200 ℃ to obtain SiBCN ceramic membrane;

the SiAlCN ceramic precursor after light fixation is soaked in toluene solution of borane dimethyl sulfide, and is cracked for 3-4 hours at 900-1200 ℃ after being dried, so as to obtain the SiAlBCN ceramic membrane.