A method for preparing a gas-sensitive ceramic material

Abstract

The application discloses a kind of preparation methods of gas-sensitive ceramic material, the present application relates to gas-sensitive sensor manufacturing technical field, for solving the problem of organic matter residue, grain excessive growth and substrate thermal stress damage in the preparation process of gas-sensitive ceramic sensitive layer, the method is prepared inorganic polar gas-sensitive ceramic nanocrystalline ink with water-based deep eutectic solvent, preheat after cantilever heating area using micro-hot plate heating electrode joule heat, using electro-hydraulic dynamics to print ink is deposited on the surface of heating area, then local irradiation sintering is carried out to deposition pattern using focused nanosecond near-infrared pulse laser, realize nanocrystalline particle fusion necking interconnection and retain oxygen vacancy defects, after sintering, sensitive layer relies on suspended film rapid cooling, the present application avoids organic matter residue and grain excessive growth, relieves substrate thermal stress damage, and is suitable for wafer-level in-situ rapid preparation of gas-sensitive ceramic sensitive layer.

Description

Technical Field

[0001] This invention relates to the field of gas sensor manufacturing technology, specifically a method for preparing a gas-sensitive ceramic material. Background Technology

[0002] In recent years, with the rapid development of IoT devices and wearable devices, semiconductor metal oxide gas-sensitive ceramic sensors based on MEMS microelectromechanical system hot plates have attracted widespread attention due to their small size and low power consumption. MEMS hot plates are usually composed of a suspended thin film of silicon nitride or silicon oxide with a submicron thickness, an embedded heating electrode, and a temperature measuring electrode. The gas-sensitive ceramic sensing layer needs to be firmly attached and sintered into a film on the cantilever heating area. The adsorption and resistance response of the target gas are achieved by relying on the working temperature provided by the heating electrode.

[0003] Currently, the most common method for preparing gas-sensitive ceramic sensitive layers in the industry is to mix and grind gas-sensitive ceramic powder with various organic solvents, thickeners, and anti-settling agents to form a paste. The specific process usually involves mixing gas-sensitive ceramic nanopowder with organic binders, thickeners, and dispersants in a certain solid content ratio, and then repeatedly grinding it with a three-roll mill to form a uniform paste.

[0004] Then, screen printing or micro-droplet coating processes are used to deposit the paste onto the surface of the cantilever heating area of ​​the MEMS device to form a wet film of a certain thickness.

[0005] The entire MEMS wafer or single device with the deposited wet film is then placed in a high-temperature muffle furnace and subjected to overall annealing and calcination for several hours according to the preset heating curve. The solvent is first evaporated at low temperature, then organic matter is burned off at medium and high temperature, and finally high temperature is maintained to achieve sintering densification and grain boundary bonding between ceramic powder particles.

[0006] The above scheme has the following shortcomings: First, the slurry contains a variety of organic fluid binders such as terpineol and ethyl cellulose. During the muffle furnace overall annealing process, the organic matter inside the thick film is difficult to completely volatilize and be discharged. The residual carbon elements at high temperature will destroy the intrinsic microstructure of the sensitive material, resulting in poor batch consistency of device response signals, accompanied by long-term baseline aging drift and cross-sensitivity problems.

[0007] Secondly, since it is necessary to completely burn off organic matter and form a strong ceramic layer, the existing process must use a high annealing temperature and a long holding time. It is generally believed in the field that a stable mechanical and electrical connection between gas-sensitive ceramic particles (sintered necking interconnection) must rely on overall high temperature and long-term annealing to achieve this. Instantaneous local heating and cooling methods are difficult to form effective interparticle connections. This is a long-standing technical bias in the field.

[0008] This application overcomes the aforementioned technical bias by using a dual-mode coupling method of MEMS Joule heating preheating and focused nanosecond pulsed laser local sintering. It achieves interparticle fusion necking interconnection within millisecond to microsecond time, which prevents microcracks, signal interruption, or even direct peeling from the MEMS substrate in the sensitive layer.

[0009] Therefore, how to achieve in-situ, localized, and rapid sintering of gas-sensitive ceramic materials on the wafer-level cantilever heating zone of MEMS micro-hotplates without using organic binders or relying on overall high-temperature furnace annealing, while taking into account batch consistency, long-term stability, and compatibility with wafer-level semiconductor back-end processes, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0010] The technical problem to be solved by the present invention is that the existing gas-sensitive ceramic sensing layer preparation method relies on a slurry system containing organic binders and an overall high-temperature furnace annealing process. This method has defects such as organic residue leading to contamination of the sensitive material, excessive growth of gas-sensitive nanocrystals due to high-temperature and long-term annealing, and thermal stress damage to the MEMS thin film structure due to global thermal cycling. It is difficult to meet the preparation requirements of good batch consistency, high long-term stability and compatibility with wafer-level semiconductor back-end processes for gas-sensitive ceramic sensing layers.

[0011] To address the aforementioned technical problems, this invention provides a method for preparing a gas-sensitive ceramic material, comprising the following:

[0012] Preparation of inorganic polar gas-sensitive ceramic nanocrystal ink: Using a water-based deep eutectic solvent as the dispersion medium, the doped metal oxide gas-sensitive ceramic nanocrystal powder is dispersed in the water-based deep eutectic solvent according to a preset solid content ratio. After ultrasonic dispersion and stirring, an inorganic polar gas-sensitive ceramic nanocrystal ink without organic binders, thickeners and anti-settling agents is obtained.

[0013] Joule heating preheating of the cantilever heating area of ​​the MEMS micro hot plate: By applying a constant current to the heating electrode of the MEMS micro hot plate, the cantilever heating area is preheated to a preheating temperature using the Joule heat generated by the heating electrode itself. The preheating temperature ranges from 150 degrees Celsius to 200 degrees Celsius, forming a basic hot bed.

[0014] Printing deposition while maintaining preheating: While maintaining the preheating temperature, an electro-hydraulic dynamics printing method is used. A bias voltage higher than the critical voltage is applied between the nozzle and the grounding electrode corresponding to the MEMS micro-hot plate. Under the action of the electric field, the inorganic polar gas-sensitive ceramic nanocrystalline ink forms a Taylor cone and stretches out microdroplets. The microdroplets are deposited on the surface of the cantilever heating area according to a preset pattern to form a wet film pattern of the gas-sensitive ceramic sensitive layer.

[0015] Local sintering of the wet film pattern: While maintaining the preheating temperature, the wet film pattern is irradiated with a focused nanosecond-level near-infrared pulsed laser along a preset scanning path, causing the wet film pattern to be locally and instantaneously heated to the sintering peak temperature, realizing the molten necking interconnection between gas-sensitive ceramic nanocrystal particles, while retaining the oxygen vacancy defects generated during the sintering process in the ceramic lattice.

[0016] Cooling: After the laser pulse irradiation ends, the gas-sensitive ceramic sensing layer is cooled to the preheating temperature by relying on the suspended thin film structure of the MEMS micro-hot plate. Then, the current applied to the heating electrode is stopped, and the gas-sensitive ceramic sensing layer is cooled to room temperature, thus completing the preparation of the gas-sensitive ceramic material.

[0017] Compared with the prior art, the beneficial effects of the present invention by adopting the above technical solution are as follows:

[0018] 1. This invention uses inorganic polar gas-sensitive ceramic nanocrystalline ink that does not contain organic binders, thickeners, or anti-settling agents. No organic additives are introduced throughout the entire process, which avoids the residue of carbonaceous substances on the surface and inside of the sensitive layer, and is conducive to improving the selectivity and long-term stability of the gas-sensitive ceramic sensitive layer for target gases.

[0019] 2. This invention utilizes the instantaneous local heating and cooling characteristics of nanosecond-level pulsed lasers to perform millisecond- to microsecond-level local sintering of the deposited layer. The action time is much shorter than that of overall furnace annealing. This can achieve sintering necking interconnection between gas-sensitive ceramic nanocrystal particles while suppressing the long-term thermal diffusion and coarsening process of the grains. This is beneficial to retaining the original size and high specific surface area of ​​the nanocrystals, thereby helping to maintain the sensitivity of the gas-sensitive material.

[0020] 3. This invention adopts a dual-mode sintering method that combines the self-Joule heating of the MEMS micro hot plate with local irradiation by focused pulsed laser. The laser energy is concentrated on the surface area of ​​the ceramic layer, and the suspended thin film substrate of the MEMS micro hot plate does not need to undergo overall high-temperature cold and hot cycle. This helps to alleviate the thermal stress problem caused by the difference in thermal expansion coefficient between heterogeneous materials and improves the bonding reliability between the sensitive layer and the MEMS substrate.

[0021] 4. Due to the rapid heating and cooling rates during the sintering process, active defects such as oxygen vacancies generated in the high-temperature stage of the sensitive layer do not have time to recombine and annihilate during the cooling process and are retained in the ceramic lattice. At the same time, the time required for interparticle sintering necking interconnection is shorter than the time required for grain coarsening. Therefore, this invention can achieve mechanical and electrical connections between particles while inhibiting excessive grain growth and retaining a high concentration of oxygen vacancy active sites, which is beneficial to improving the gas sensitivity of gas-sensitive ceramic materials.

[0022] 5. The fabrication process of this invention can continuously complete ink deposition and local sintering on a MEMS micro-hot plate wafer carrier without transferring to an overall high-temperature furnace for processing. It has the processing characteristics of being compatible with wafer-level semiconductor back-end processes, which is conducive to achieving large-scale low-cost mass production. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the main process flow in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the wafer mass production process with online inspection in an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the working logic of the integrated preparation system in an embodiment of the present invention. Detailed Implementation

[0026] The following is in conjunction with the appendix Figure 1-3 The specific embodiments of the present invention will be further described below. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0027] The technical solution of the present invention will be further described below with reference to specific embodiments. The following embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0028] The gas-sensitive ceramic material preparation method provided in this embodiment relies on an integrated system of inorganic ink electro-hydraulic dynamics printing and dual-modal local sintering. This system includes a vacuum adsorption-type mobile stage for carrying the MEMS micro-hotplate wafer to be processed, an electro-hydraulic dynamics high-precision printing unit located on one side above the stage, a focused nanosecond pulse near-infrared laser scanning sintering unit located on the other side above the stage, an online temperature and resistance feedback monitoring unit, and a central controller for coordinating the work of each unit. The mobile stage integrates a heating power interface for energizing the heating electrodes of the MEMS micro-hotplate and applying Joule heating preheating. The electro-hydraulic dynamics printing unit includes... The system includes an inorganic gas-sensitive slurry storage tank, a precision micro-pump, and a metal nozzle that applies a high-voltage bias. The metal nozzle is positioned directly over the MEMS cantilever heating area on the wafer surface. The pulsed laser sintering unit includes a nanosecond-level near-infrared pulsed laser, a beam expander and shaper optical path, a focusing objective, and a two-dimensional galvanometer scanning system. The laser spot is focused and then vertically illuminates the sensitive layer area after printing. The online temperature and resistance feedback monitoring unit includes an infrared temperature probe and a real-time device resistance acquisition circuit. Both are connected to a central controller. The central controller coordinates the stage movement, heating power supply, printing sequence, laser pulse parameters, and scanning path to achieve continuous automated operation of material deposition and dual-mode sintering.

[0029] In the preparation of inorganic polar gas-sensitive ceramic nanocrystal ink, a low-surface-tension water-based deep eutectic solvent is used as the dispersion medium. Tin dioxide-doped nanocrystal powder or zinc oxide-doped nanocrystal powder is added to the inorganic solvent according to a preset solid content ratio. In this embodiment, the solid content is 10% to 30% by mass fraction. After ultrasonic dispersion and high-speed stirring, an inorganic polar gas-sensitive slurry ink without any organic polymer binder, thickener, or anti-settling agent is obtained. This ink has both viscosity and conductivity characteristics suitable for electro-hydraulic dynamics printing, and also has the characteristic of rapid solvent evaporation and removal under normal atmospheric temperature.

[0030] After loading and aligning the MEMS micro-hotplate wafer, the wafer is first fixed on the moving stage of the fabrication system by vacuum adsorption. The positions of the cantilever heating areas of each MEMS micro-hotplate on the wafer are aligned with the processing coordinate system of the electro-hydraulic dynamics inkjet printing unit and the laser scanning unit. Then, a constant current is applied to the heating electrodes of the MEMS micro-hotplate by the stage heating power supply. The Joule heat generated by the plate itself is used to preheat the cantilever heating areas to the range of 150 to 200 degrees Celsius, forming a uniform basic hot bed for evaporating residual solvents and initially activating nanocrystalline particles.

[0031] While maintaining the above preheating state, the electro-hydraulic dynamics inkjet printing unit is started. A pulsed high-voltage bias voltage is applied between the metal nozzle and the ground electrode below the MEMS micro-hot plate, so that the inorganic ink at the nozzle tip overcomes its own surface tension under the action of electric field force, forming a Taylor cone and stretching out a micro-nano-scale jet. The micro-droplets formed by the jet breakup are precisely deposited on the predetermined patterned area of ​​the MEMS cantilever heating area under the guidance of the electric field. The printing accuracy can reach the sub-micron level, realizing precise patterned coverage of the tiny cantilever heating area without overflowing to the surrounding support structure.

[0032] The critical voltage required for the Taylor cone to become unstable and form a jet during electro-hydraulic inkjet printing can be described by the following relationship:

[0033] ;

[0034] In the formula, The critical bias voltage required to form a stable Taylor cone and stretch the jet;

[0035] These are empirical coefficients related to the geometry of the inkjet printing unit;

[0036] The surface tension coefficient of inorganic ink;

[0037] This refers to the working distance between the nozzle and the grounding electrode.

[0038] The nozzle outlet inner diameter is [value missing]. When the actual bias voltage applied between the nozzle and the ground electrode is higher than [value missing], [value missing]. At this time, the ink forms a stable Taylor cone at the tip of the nozzle and is continuously stretched into a microjets, thereby achieving continuous and controllable patterned deposition.

[0039] After the sensitive layer patterning deposition is completed, there is no need to transfer the entire device to a high-temperature furnace. Instead, subsequent sintering is completed directly on the original wafer stage. While maintaining the preheated state, a focused and shaped nanosecond-level near-infrared pulsed laser is introduced directly above the cantilever heating area. In this embodiment, the center wavelength of the laser is in the near-infrared band, and the pulse width is on the order of nanoseconds. The deposited sensitive layer pattern is subjected to millisecond-level rapid photothermal irradiation point by point or row by row according to the preset scanning path, so that the sensitive layer is locally and instantaneously heated to a sintering peak temperature much higher than the preheating temperature, realizing the molten necking interconnection between nano-ceramic particles. After the laser pulse ends, the sensitive layer is rapidly cooled to the preheating temperature due to the low heat capacity characteristics of the micro-hot plate suspended thin film structure.

[0040] The instantaneous heating rate during the localized laser irradiation phase can be expressed as:

[0041] ;

[0042] In the formula, The instantaneous heating rate generated by laser irradiation;

[0043] This refers to the peak sintering temperature reached by the sensitive layer during the laser sintering stage.

[0044] This is the base preheating temperature for the Joule heating preheating stage;

[0045] This represents the effective duration of a single laser pulse on the sensitive layer.

[0046] The cooling rate of the sensitive layer after the laser pulse ends can be expressed as:

[0047] ;

[0048] In the formula, The cooling rate at which the sensitive layer falls from its peak temperature back to its preheating temperature;

[0049] In this embodiment, the time taken for the pullback process is... and All can be achieved The heating and cooling rates are significantly higher than those of traditional in-furnace annealing.

[0050] Because the heating and cooling rates during the sintering process are relatively fast, the high concentration of oxygen vacancies and other active defects generated in the high-temperature stage of the sensitive layer do not have time to recombine and annihilate through thermal diffusion during the cooling process, and are thus retained in situ in the ceramic lattice. At the same time, the time required for interparticle sintering necking interconnection is much shorter than the characteristic time required for grain coarsening. Therefore, while achieving mechanical and electrical connections between particles, excessive grain growth is well suppressed.

[0051] The relationship between the oxygen vacancy concentration in the sensitive layer after sintering and the peak sintering temperature can be approximated as follows:

[0052] ;

[0053] In the formula, The concentration of oxygen vacancies in the gas-sensitive ceramic layer after sintering;

[0054] This is a pre-exponential factor constant related to the probability of intrinsic defects in the material.

[0055] The energy for the formation of oxygen vacancies;

[0056] Boltzmann's constant;

[0057] This is the peak temperature of laser sintering, due to the fact that in this embodiment... The high concentration of oxygen vacancies generated at high temperatures according to the above formula does not have time to undergo reverse recombination during the cooling stage, and therefore are ultimately retained in the crystal lattice, becoming active sites that enhance the gas sensor's sensitivity.

[0058] After the laser pulse scan is completed, the sensitive layer rapidly cools to the preheating temperature due to the low heat capacity of the suspended thin film structure. Then the heating power is turned off, allowing the device to cool naturally to room temperature, thus completing the in-situ sintering of the gas-sensitive ceramic sensitive layer on the cantilever heating area of ​​the MEMS micro-hot plate.

[0059] The morphology and electrical parameters of the sintered sensitive layer are detected by an online infrared temperature probe and a real-time resistance acquisition circuit. In this embodiment, the preset threshold is determined based on the target resistance range of the gas-sensitive ceramic sensitive layer under room temperature calibration conditions. For example, the room temperature resistance value of the sensitive layer is taken as 10 kΩ to 100 kΩ as the qualification criterion. If the detection result does not reach the preset threshold, the corresponding area is subjected to supplementary laser scanning sintering.

[0060] If the test is successful, the stage is moved to the position corresponding to the MEMS micro-hot plate to be processed on the upper and lower parts of the wafer, and the above preheating, inkjet deposition and local sintering processes are repeated until the sensitive layer of the cantilever heating area of ​​all MEMS micro-hot plates on the whole wafer is prepared.

[0061] Regarding the structure of MEMS micro hot plate, its bottom layer is a silicon substrate support frame, and the middle part is a suspended area formed by back cavity etching;

[0062] Above the suspended area is a silicon nitride or silicon oxide composite insulating cantilever film. The film contains a serpentine heating electrode and a temperature measuring electrode. The two ends of the electrodes are led out to the metal pads at the edge of the substrate via the cantilever beam.

[0063] Above the cantilever film is a gas-sensitive ceramic sensitive layer deposited and sintered by the method of the present invention. A pair of measuring electrodes are attached to both ends of the sensitive layer to extract the resistance signal of the sensitive layer. The heating electrode, the temperature measuring electrode and the measuring electrode are electrically insulated from each other. The heating electrode is used to provide the working temperature, the temperature measuring electrode is used to monitor the actual temperature of the cantilever heating zone in real time, and the measuring electrode is used to extract the resistance signal generated by the gas-sensitive ceramic sensitive layer as the concentration of the target gas changes.

[0064] As an alternative embodiment of the present invention, in application scenarios where it is inconvenient to apply a high-voltage electric field, a piezoelectric microdroplet jet nozzle can be used instead of an electrohydraulic dynamic nozzle. The nozzle cavity is driven by piezoelectric ceramic to generate instantaneous pressure pulses, which spray inorganic gas-sensitive ink in the form of microdroplets and deposit it in a pattern on the MEMS cantilever heating area. The subsequent Joule heating preheating and pulsed laser local sintering steps remain unchanged, and the same in-situ deposition and ultra-fast sintering effect without organic additives can be achieved. However, the deposition accuracy is slightly lower than that of the electrohydraulic dynamic inkjet printing method.

[0065] As another alternative embodiment of the present invention, when the sensitive material has a high absorption coefficient in the ultraviolet band, a continuous wave ultraviolet laser can be used in conjunction with a high-speed galvanometer to perform rapid point scanning. By controlling the dwell time of a single point, an instantaneous local heating and rapid cooling effect similar to pulse irradiation can be achieved. Similarly, based on the Joule heating preheating of MEMS, the in-situ retention of interparticle melting and necking interconnection and oxygen vacancy defects can be achieved, which is an effective supplement to the nanosecond pulse near-infrared laser scheme.

[0066] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a gas-sensitive ceramic material, characterized in that, Includes the following steps: Preparation of inorganic polar gas-sensitive ceramic nanocrystal ink: Using a water-based deep eutectic solvent as the dispersion medium, the doped metal oxide gas-sensitive ceramic nanocrystal powder is dispersed in the water-based deep eutectic solvent according to a preset solid content ratio. After ultrasonic dispersion and stirring, an inorganic polar gas-sensitive ceramic nanocrystal ink without organic binders, thickeners and anti-settling agents is obtained. Joule heating preheating of the cantilever heating area of ​​the MEMS micro hot plate: By applying a constant current to the heating electrode of the MEMS micro hot plate, the cantilever heating area is preheated to a preheating temperature using the Joule heat generated by the heating electrode itself. The preheating temperature ranges from 150 degrees Celsius to 200 degrees Celsius, forming a basic hot bed. Printing deposition while maintaining preheating: While maintaining the preheating temperature, an electro-hydraulic dynamics printing method is used. A bias voltage higher than the critical voltage is applied between the nozzle and the grounding electrode corresponding to the MEMS micro-hot plate. Under the action of the electric field, the inorganic polar gas-sensitive ceramic nanocrystalline ink forms a Taylor cone and stretches out microdroplets. The microdroplets are deposited on the surface of the cantilever heating area according to a preset pattern to form a wet film pattern of the gas-sensitive ceramic sensitive layer. Local sintering of the wet film pattern: While maintaining the preheating temperature, the wet film pattern is irradiated with a focused nanosecond-level near-infrared pulsed laser along a preset scanning path, causing the wet film pattern to be locally and instantaneously heated to the sintering peak temperature, realizing the molten necking interconnection between gas-sensitive ceramic nanocrystal particles, while retaining the oxygen vacancy defects generated during the sintering process in the ceramic lattice. Cooling: After the laser pulse irradiation ends, the gas-sensitive ceramic sensing layer is cooled to the preheating temperature by relying on the suspended thin film structure of the MEMS micro-hot plate. Then, the current applied to the heating electrode is stopped, and the gas-sensitive ceramic sensing layer is cooled to room temperature, thus completing the preparation of the gas-sensitive ceramic material.

2. The method for preparing gas-sensitive ceramic material according to claim 1, characterized in that, In the inkjet deposition step, the critical voltage satisfies the following relationship: ； in, The critical bias voltage required to form a stable Taylor cone and stretch the jet. These are empirical coefficients related to the geometry of the inkjet printing unit. The surface tension coefficient of the inorganic polar gas-sensitive ceramic nanocrystalline ink is [missing information]. The working distance between the nozzle and the grounding electrode. The nozzle's outlet inner diameter is given, and the bias voltage applied between the nozzle and the grounding electrode is higher than the critical voltage. .

3. The method for preparing gas-sensitive ceramic material according to claim 1, characterized in that, The gas-sensitive ceramic nanocrystal powder is one of tin dioxide-doped nanocrystals or zinc oxide-doped nanocrystals.

4. The method for preparing gas-sensitive ceramic material according to claim 1, characterized in that, In the local sintering step, the instantaneous heating rate of the gas-sensitive ceramic sensing layer and cooling rate They are respectively: ； ； in, The sintering peak temperature is... The preheating temperature is... The effective duration of a single laser pulse on the gas-sensitive ceramic sensing layer. The heating rate is the time it takes for the gas-sensitive ceramic sensing layer to drop from the peak sintering temperature back to the preheating temperature. and the cooling rate All are not less than And the preheating temperature With the sintering peak temperature The difference is set such that the time required for the sintering and necking interconnection between the gas-sensitive ceramic nanocrystal particles is shorter than the grain coarsening characteristic time, while being longer than the time required for the recombination and annihilation of oxygen vacancy defects.

5. The method for preparing gas-sensitive ceramic material according to claim 1, characterized in that, In the local sintering step, the oxygen vacancy concentration retained within the gas-sensitive ceramic sensing layer With the sintering peak temperature The following relationship must be satisfied: ； in, This is a pre-exponential factor constant related to the probability of intrinsic defect generation in the gas-sensitive ceramic nanocrystals. The energy for the formation of oxygen vacancies. is the Boltzmann constant.

6. The method for preparing gas-sensitive ceramic material according to claim 1, characterized in that, In the inkjet deposition step, the pattern formed by the microdroplets deposited on the surface of the cantilever heating zone has a precision of submicron level.

7. The method for preparing gas-sensitive ceramic material according to claim 1, characterized in that, Also includes: The resistance parameter of the cooled gas-sensitive ceramic layer is detected. If the detection result does not reach the preset threshold, the local sintering step is repeated on the gas-sensitive ceramic layer. If the detection result reaches the preset threshold, the stage is moved to the corresponding position of the adjacent MEMS hot plate, and the Joule heating preheating step, the inkjet deposition step, and the local sintering step are repeated on the cantilever heating area of ​​the adjacent MEMS hot plate until the gas-sensitive ceramic layer of all cantilever heating areas of the MEMS hot plate on the MEMS hot plate wafer is fabricated.

8. A gas-sensitive ceramic material preparation system, characterized in that, include: A mobile stage is used to carry MEMS micro-hot plate wafers. The mobile stage is equipped with a vacuum adsorption structure and a heating power interface. The heating power interface is used to apply a constant current to the heating electrodes on the MEMS micro-hot plate wafer. An electro-hydraulic dynamics inkjet printing unit is disposed on one side above the movable stage. The electro-hydraulic dynamics inkjet printing unit includes a liquid storage tank for containing inorganic polar gas-sensitive ceramic nanocrystal ink, a micro-pump connected to the liquid storage tank, and a metal nozzle connected to the micro-pump and applying a high-voltage bias voltage. The metal nozzle is directly facing the cantilever heating area of ​​the MEMS micro-hotplate on the MEMS micro-hotplate wafer. A pulsed laser sintering unit is disposed above the movable stage and on the opposite side of the electro-hydraulic dynamic inkjet printing unit. The pulsed laser sintering unit includes a nanosecond-level near-infrared pulsed laser, a beam expanding and shaping optical path connected to the optical path of the nanosecond-level near-infrared pulsed laser, a focusing objective connected to the optical path of the beam expanding and shaping optical path, and a two-dimensional galvanometer scanning system that cooperates with the focusing objective. The online detection unit includes an infrared temperature probe and a real-time resistance acquisition circuit, both of which are positioned facing the cantilever heating area. The central controller is electrically connected to the moving stage, the heating power interface, the electro-hydraulic dynamics inkjet printing unit, the pulsed laser sintering unit, and the online detection unit, respectively, and is used to control the movement of the moving stage, the power-on sequence of the heating power interface, the inkjet printing sequence of the electro-hydraulic dynamics inkjet printing unit, and the laser pulse parameters and scanning path of the pulsed laser sintering unit.

9. The gas-sensitive ceramic material preparation system according to claim 8, characterized in that, The MEMS micro hot plate includes a silicon substrate support frame, an insulating cantilever film disposed on the silicon substrate support frame and suspended above the back cavity, and a heating electrode and a temperature measuring electrode embedded inside the insulating cantilever film. The heating electrode and the temperature measuring electrode are both led out to metal pads at the edge of the silicon substrate support frame through cantilever beams.

10. The gas-sensitive ceramic material preparation system according to claim 8, characterized in that, The central controller is also used to determine whether the gas-sensitive ceramic sensitive layer has reached a preset threshold based on the resistance parameters collected by the online detection unit, and to control the pulsed laser sintering unit to perform supplementary sintering on the corresponding area if the preset threshold has not been reached.

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