Corrosion-resistant high-reliability MEMS gas sensor and preparation method thereof

Abstract

The invention discloses a corrosion-resistant high-reliability MEMS gas sensor and a preparation method thereof, and relates to the field of new energy battery monitoring, and the corrosion-resistant high-reliability MEMS gas sensor comprises a shell mechanism which comprises a sensor shell, a bonding pad located on the inner wall of the sensor shell, a breathable area located at the top of the sensor shell and an anti-corrosion filter membrane located on the breathable area; and the micro hot plate mechanism comprises a sensor substrate arranged in the sensor shell, a first insulating medium layer located on the surface of the sensor substrate, and a Pt heating electrode located on the surface of the first insulating medium layer. The sensor disclosed by the invention can be arranged in a lithium battery cell, can quickly detect characteristic gas generated by decomposition of a battery electrolyte, and can perform early warning on out-of-control of the battery, so that the operation safety of the battery is guaranteed. And the sensor adopts a metal oxide semiconductor as a sensitive material and an MEMS micro hot plate as a sensor heating substrate, so that the cost is low, the power consumption is low, and batch preparation can be realized.

Description

Technical Field

[0001] The present invention relates to the field of new energy battery monitoring, and in particular to a corrosion-resistant and highly reliable MEMS gas sensor and a preparation method thereof. Background Art

[0002] In recent years, new energy vehicles, as new types of locomotives, have been highly valued by automobile manufacturers. The new energy vehicle industry has developed rapidly. At present, batteries are undoubtedly the most core and key components of new energy vehicles, which determine the service life and safety of the vehicle. At present, most new energy vehicles use lithium-ion batteries as energy carriers. Lithium-ion batteries have the advantages of long service life and high storage energy density. However, lithium primary batteries have poor safety problems and are at risk of explosion. Therefore, improving the safety of lithium-ion batteries is of great significance to promoting the development of new energy vehicles.

[0003] In addition to taking measures to improve battery safety in battery manufacturing and battery pack design, real-time and accurate detection of battery operating conditions during battery use is also the key to ensuring vehicle safety. Studies have shown that in the early stages of battery runaway, the BMS system cannot detect battery failures because characteristic identification parameters such as battery temperature, discharge voltage, and discharge current change very slowly. At this time, the electrochemical reaction inside the battery will produce gases such as hydrogen, carbon monoxide, and carbon dioxide. Therefore, early warning of battery thermal runaway can be achieved by detecting the concentration of these gases. However, since the electrolyte inside the battery has a certain corrosive effect on the sensitive materials and circuits of the sensor, most gas sensors are currently placed outside the battery, which to a certain extent causes a lag in detection. For this reason, a corrosion-resistant and highly reliable MEMS gas sensor and a preparation method thereof are proposed. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention is proposed.

[0005] Therefore, the present invention aims to solve the problem in the prior art that the sensor has poor corrosion resistance and is difficult to be arranged inside the battery, resulting in detection lag.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: a corrosion-resistant and highly reliable MEMS gas sensor, comprising: a housing structure, including a sensor housing, a pad located on the inner wall of the sensor housing, a gas permeable area located on the top of the sensor housing, and an anti-corrosion filter membrane located on the gas permeable area; and

[0007] The micro-hotplate mechanism comprises a sensor substrate arranged inside a sensor housing, a first insulating dielectric layer located on the surface of the sensor substrate, a Pt heating electrode located on the surface of the first insulating dielectric layer, a second insulating dielectric layer located on the surface of the Pt heating electrode, and an Au test electrode located on the surface of the second insulating dielectric layer;

[0008] The sensor substrate comprises a buried oxide layer and a Si substrate layer, wherein the Si substrate layer is arranged below the buried oxide layer;

[0009] A sensitive area is arranged on the Au test electrode.

[0010] Beneficial effects of the present invention:

[0011] (1) The silicone resin film is oleophobic, corrosion-resistant, and has high air permeability, ensuring that the sensor is not corroded by the electrolyte.

[0012] (2) The sensor is built into the lithium battery cell and can quickly detect the characteristic gas produced by the decomposition of the battery electrolyte, provide early warning of battery runaway, and ensure safe battery operation.

[0013] (3) The sensor uses metal oxide semiconductor as the sensitive material and MEMS micro-hotplate as the sensor heating substrate. It has low cost, low power consumption and can be mass-produced.

[0014] In view of the above problems existing in the prior art, the present invention is proposed.

[0015] Therefore, the present invention aims to solve the problem in the prior art that the sensor substrate is inconvenient to prepare and is large in size and difficult to be integrated into the battery.

[0016] As a preferred solution of the method for preparing the corrosion-resistant and highly reliable MEMS gas sensor of the present invention, the method comprises: stacking the buried oxide layer and the substrate layer as a base;

[0017] Pre-treating the substrate;

[0018] Placing the substrate in an LPCVD device, and introducing a mixed gas to decompose the mixed gas and deposit a first insulating dielectric layer on the surface of the substrate;

[0019] A layer of hexamethyldisilazane (HMDS) is covered on the surface of the first insulating dielectric layer;

[0020] performing photolithography on the substrate surface;

[0021] A Pt film is sputtered and grown on the surface of the silicon wafer, and the silicon wafer is immersed in an immersion mechanism containing an acetone solution, and finally a Pt heating electrode is retained on the surface of the silicon wafer;

[0022] Placing the substrate in a PECVD device and introducing a mixed gas to decompose the mixed gas and deposit a second insulating dielectric layer on the surface of the substrate;

[0023] Continue to perform transfer photolithography on the second insulating dielectric layer;

[0024] A layer of Au film is sputtered on the surface of a silicon wafer, and the silicon wafer is immersed in acetone, and finally an Au test electrode is retained on the surface of the silicon wafer;

[0025] The surface of the substrate layer is photolithographically processed, and then the substrate layer is deeply etched with bulk silicon to produce a MEMS gas sensor.

[0026] As a preferred solution of the method for preparing the corrosion-resistant and highly reliable MEMS gas sensor of the present invention, the immersion mechanism comprises a water tank, a drain outlet and a water inlet are sequentially arranged on one side of the bottom of the water tank, a water storage member is arranged inside the water tank, a buoyancy member is also arranged inside the water tank, the buoyancy member is arranged on one side of the water storage member, and a switch member is arranged on the outside of the water storage member.

[0027] As a preferred solution of the method for preparing the corrosion-resistant and highly reliable MEMS gas sensor of the present invention, the water storage component comprises a water tank, a connecting pipe is arranged at the bottom of the water tank, and a flushing pipe is also arranged on the outside of the water tank.

[0028] As a preferred solution of the method for preparing the corrosion-resistant and highly reliable MEMS gas sensor described in the present invention, the buoyancy member includes a float ball, and a first float rod and a second float rod are sequentially arranged on the outer side of the float ball, and the outer walls of the first float rod and the second float rod are both provided with push grooves, and one end of the push groove is connected to a straight groove.

[0029] As a preferred solution of the method for preparing the corrosion-resistant and high-reliability MEMS gas sensor described in the present invention, the switch component includes a fixed disk installed on the outside of the water tank, a rotating disk is rotatably provided on the surface of the fixed disk, a push column is fixedly provided on the inner wall of the rotating disk, a guide groove is also provided on the bottom surface of the rotating disk, guide balls are symmetrically embedded in the guide groove, the bottoms of the two guide balls are provided with splints, the bottoms of the splints are provided with positioning blocks, and positioning grooves are symmetrically provided on the fixed disk.

[0030] As a preferred solution of the method for preparing the corrosion-resistant and highly reliable MEMS gas sensor of the present invention, the push groove is arranged in an inclined spiral along the outer wall of the first floating rod, and the push groove and the push column are in sliding fit.

[0031] As a preferred solution of the method for preparing the corrosion-resistant and highly reliable MEMS gas sensor of the present invention, the clamping plate and the rotating disk form a linkage structure through a guide groove, and the guide groove is arranged in an elliptical ring shape.

[0032] As a preferred solution of the method for preparing the corrosion-resistant and highly reliable MEMS gas sensor of the present invention, wherein: the outer wall of the first floating rod is provided with a pushing surface, and a connecting groove is left on the pushing surface;

[0033] The pushing surface is arranged in a corrugated shape.

[0034] As a preferred solution of the method for preparing the corrosion-resistant and highly reliable MEMS gas sensor of the present invention, wherein: sieve holes are evenly provided on the outer wall of the cleaning tank;

[0035] The switch member is also connected to a swing member, which includes a swing rod, a positioning seat is arranged on the middle section of the swing rod, and a connecting block is arranged at the end of the swing rod.

[0036] The beneficial effects of the present invention are as follows: the sensor micro-hotplate substrate is prepared by adopting the MEMS process, and the substrate size is at the level of hundreds of microns, which facilitates the integration of the sensor into the battery.

[0037] Moreover, the preparation method uses metal oxide semiconductor materials as the sensitive materials of the sensor, which has high sensitivity and fast response characteristics. At the same time, the sensor cost is low and it is easy to prepare in batches. The sensor has the characteristics of high sensitivity and high stability in response to gas;

[0038] At the same time, the immersion mechanism in the preparation method can automatically rinse the sensor substrate according to the change in liquid level as the solution is discharged after the photoresist is dissolved in the acetone solution, so as to ensure the complete detachment of excess photoresist, avoid the photoresist remaining on the surface of the substrate and affect the user's subsequent removal and processing of the substrate, and cooperate with the swing part to screen the detached photoresist impurities out of the cleaning tank, so as to further eliminate the influence of excess photoresist on the subsequent processing of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0040] Figure 1 A schematic diagram of the assembly structure of a micro-hot plate mechanism and a shell mechanism in a corrosion-resistant and highly reliable MEMS gas sensor according to an embodiment of the present invention;

[0041] Figure 2 A schematic structural diagram of a micro-hot plate mechanism in a corrosion-resistant and highly reliable MEMS gas sensor according to an embodiment of the present invention;

[0042] Figure 3 A schematic diagram of the matching structure of a sensor housing and an anti-corrosion filter membrane in a corrosion-resistant and highly reliable MEMS gas sensor according to an embodiment of the present invention;

[0043] Figure 4 A schematic diagram of the response of a sensor to ethylene gas in a corrosion-resistant and highly reliable MEMS gas sensor according to an embodiment of the present invention;

[0044] Figure 5 A flow chart of the preparation of a micro-hot plate mechanism in a method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to an embodiment of the present invention;

[0045] Figure 6 A schematic diagram of the structure of an immersion mechanism in a method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to an embodiment of the present invention;

[0046] Figure 7 A schematic cross-sectional structure diagram of an immersion mechanism in a method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to an embodiment of the present invention;

[0047] Figure 8 A schematic diagram of the structure of a buoyancy member of an immersion mechanism in a method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to an embodiment of the present invention;

[0048] Fig. 9 A schematic diagram of the exploded structure of a switch component and a swing component of an immersion mechanism in a method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to an embodiment of the present invention.

[0049] In the figure: 100, housing mechanism; 101, sensor housing; 102, pad; T, air permeable area; 103, anti-corrosion filter membrane; 200, micro hot plate mechanism; 201, sensor substrate; 201a, buried oxide layer; 201b, Si substrate layer; 202, first insulating dielectric layer; 203, Pt heating electrode; 204, second insulating dielectric layer; 205, Au test electrode; M, sensitive area; 300, immersion mechanism; 301, water tank; 302, drain outlet; 303, water inlet; 304, water storage member; 304a, water tank; 304b, connecting pipe; 304c, Flushing pipe; 305, buoyancy member; 305a, float; 305b, first float rod; 305c, second float rod; 305d, push groove; 305e, straight groove; 305f, push surface; 305g, connecting groove; 306, switch member; 306a, fixed disk; 306b, rotating disk; 306c, push column; 306d, guide groove; 306e, guide ball; 306f, clamp; 306g, positioning block; 306h, positioning groove; 307, cleaning tank; 307a, sieve hole; 308, swing member; 308a, positioning seat; 308b, swing rod; 308c, connecting block. DETAILED DESCRIPTION

[0050] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0051] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0052] Secondly, the present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0053] Furthermore, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0054] Example 1

[0055] Reference Figure 1-4, this embodiment provides a corrosion-resistant and highly reliable MEMS gas sensor.

[0056] The corrosion-resistant and highly reliable MEMS gas sensor comprises a housing mechanism 100 and a micro-hotplate mechanism 200 .

[0057] Specifically, the shell mechanism 100 includes a sensor shell 101, a welding pad 102 is arranged on the inner wall of the sensor shell 101, and a breathable area T is also reserved on the top of the sensor shell 101, and an anti-corrosion filter membrane 103 is arranged on the breathable area T. The anti-corrosion filter membrane 103 is made of silicone resin material. The use of silicone resin material improves the sensor's resistance to battery electrolyte corrosion while ensuring the air permeability.

[0058] The micro-hotplate mechanism 200 includes a sensor substrate 201 disposed inside the sensor housing 101. The sensor substrate 201 includes a buried oxide layer 201a and a Si substrate layer 201b. The buried oxide layer 201a has a depth of 3.5 μm, a thickness of 1.5 μm, and a thickness of 400 μm. The Si substrate layer 201b has a thickness of 400 μm, and subsequent etching thereof is facilitated by using the 400 μm Si substrate layer 201b. The Si substrate layer 201b is disposed at the lower part of the buried oxide layer 201a. A first insulating dielectric layer 202 on the surface of 201, a Pt heating electrode 203 on the surface of the first insulating dielectric layer 202, a second insulating dielectric layer 204 on the surface of the Pt heating electrode 203, and an Au test electrode 205 on the surface of the second insulating dielectric layer 204, and the Au test electrode 205, the Pt heating electrode 203 and the pad 102 are all welded and connected by gold wire pressure welding, and a sensitive area M is set on the Au test electrode 205, and the sensitive area M is made by dripping the sensor sensitive material on the test electrode.

[0059] The first insulating dielectric layer 202 and the second insulating dielectric layer 204 are both made of Si3N4. Si3N4 has good corrosion resistance and can effectively protect the Pt heating electrode 203 to prevent the Pt heating electrode 203 from being corroded by corrosive gases.

[0060] The sensitive area M on the Au test electrode 205 is connected to the second insulating dielectric layer 204 by a beam, and the suspended structure reduces the voltage required for the material to reach the required operating temperature, which helps to reduce the power consumption of the sensor and reduce the cost. The cantilever beam structure greatly reduces the power consumption of the sensor.

[0061] The sensor's sensitive material is a metal oxide semiconductor material, which has high sensitivity and fast response characteristics. At the same time, the sensor has low cost and is easy to prepare in batches. The metal oxide sensor's response to 100ppm, 150ppm, 200ppm and 250ppm ethylene gas has been tested. Figure 4As shown, it has the characteristics of high sensitivity and high stability, and the response time is about 7s.

[0062] Example 2

[0063] Reference Figure 1-9 , which is the second embodiment of the present invention, provides a method for preparing a corrosion-resistant and highly reliable MEMS gas sensor, specifically:

[0064] 1) stacking the buried oxide layer 201a and the substrate layer as a base;

[0065] The buried oxide layer 201a has a depth of 3.5 μm, a thickness of 1.5 μm, and a thickness of 400 μm of the Si substrate layer 201b, so as to facilitate subsequent etching processes on the substrate.

[0066] 2) Pre-treat the substrate with acetone, concentrated sulfuric acid, etc.

[0067] 3) Place the substrate in an LPCVD device, evacuate to below 40 Pa, preheat to 600°C, introduce a mixed gas of NH3 and DCS (SiH2Cl2) to decompose it and deposit a first insulating dielectric layer 202 of Si3N4 on the surface of the substrate;

[0068] The LPCVD process temperature is 600℃ for 50min. Compared with the low-temperature PECVD process, the insulating layer grown by the LPCVD process is more dense and has a better bond with the substrate;

[0069] 4) Covering the surface of the first insulating dielectric layer 202 with a layer of hexamethyldisilazane (HMDS);

[0070] Hexamethyldisilazane coating enhances the adhesion of photoresists;

[0071] 5) Photolithography of the substrate surface;

[0072] The photoresist used was AZ5214, which has poor adhesion and is easy to peel off. The coating speed was 1500r / min and the coating time was 60s. After the photoresist was evenly spin-coated on the surface of the silicon wafer, it was pre-baked at 90°C for 120s. The UV lamp exposure power was 260W and the exposure time was 3.5s. After exposure, it can be developed using a self-prepared sodium hydroxide solution, which is convenient for development.

[0073] 6) Sputtering a Pt film on the surface of the silicon wafer, and immersing the silicon wafer in acetone, and finally retaining the Pt heating electrode 203 on the surface of the silicon wafer;

[0074] The thickness of the Pt film is The thickness of Pt determines the resistance of the heating resistor. If it is too thin, the resistance will be too large and the power consumption will be high. If it is too thick, it will affect the subsequent process. Therefore, the thickness of Pt is selected to be Soak the substrate in acetone for 36 hours. Since the photoresist will dissolve in acetone, the excess photoresist and the metal on its surface can be removed by soaking in acetone. Finally, a Pt heating layer corresponding to the mask pattern is retained on the silicon wafer surface.

[0075] 7) placing the substrate in a PECVD device, and introducing a mixed gas to decompose the mixed gas and deposit a second insulating dielectric layer 204 on the surface of the substrate;

[0076] The deposition method of the second insulating dielectric layer 204 is roughly the same as step three, except that the growth of the Si3N4 layer after photolithography adopts the PECVD process, that is, the substrate is placed in the PECVD equipment, and the process temperature is 90°C. It should be noted that in this step, the PECVD process temperature should be lower than 100°C. High temperature will cause AZ5214 to denature and make it difficult for the photoresist to fall off during stripping. That is, after the photoresist is soaked in acetone solution, it is still difficult to strip it by ultrasound or other methods. It needs to be wiped with a cotton swab many times, which will damage the surface pattern;

[0077] 8) Continue to perform conversion photolithography on the second insulating dielectric layer 204;

[0078] When the AZ5214 photoresist is used on the second insulating dielectric layer 204, it should be converted to a negative photoresist, which is conducive to metal stripping. The conversion process is as follows: after the first exposure, the silicon wafer is post-baked at 120°C for 3 minutes. If the temperature is too high, it will not be able to be reversed. If the temperature is too low, the photoresist will be very thin after development, resulting in the photoresist being etched through during etching. After the post-baking, the silicon wafer is quickly transferred to deionized water and cooled to room temperature. After drying, it is exposed at room temperature (260W) for 11 seconds, so that the properties of the AZ5214 photoresist during development are negative photoresist;

[0079] 9) Sputtering a layer of Au thin film on the surface of the silicon wafer, and immersing the silicon wafer in acetone, and finally retaining the Au test electrode 205 on the surface of the silicon wafer;

[0080] The substrate is immersed in acetone for 36 hours. Since the photoresist will dissolve in acetone, the excess photoresist and the metal on its surface can be removed by immersing in acetone. Finally, the Au test electrode 205 is retained. Since the interdigital spacing of the interdigital electrodes in the Au test electrode 205 layer is small (less than 10 μm), conversion treatment is required when applying the photoresist.

[0081] 10) Photolithography is performed on the surface of the substrate layer, and then the substrate layer is deeply etched by bulk silicon to obtain a MEMS gas sensor;

[0082] Before deep etching of bulk silicon, a layer of photoresist is spin-coated on the surface of the substrate layer as a soft etching mask. The thicker AZ4903 photoresist is used, the coating rate is 3000r / min, and the coating time is 60s. After the photoresist is evenly spin-coated on the surface of the silicon wafer, it is pre-baked at 120°C for 2.5min, exposed at room temperature (260W) for 15s and developed. Next, the substrate layer is subjected to deep etching of bulk silicon. Due to the presence of the buried oxide layer 201a as an etching stop layer, the etching will stop at about 5μm from the substrate surface, and a thin film with a thickness of less than 10μm is retained in the heating area.

[0083] Example 3

[0084] Reference Figure 1-9 , which is the third embodiment of the present invention,

[0085] The immersion mechanism 300 includes a water tank 301 with an acetone solution inside. The photoresist can be dissolved in acetone, so that the excess photoresist on the micro-hotplate during the preparation process and the metal on its surface can be removed by immersing in acetone. A drain port 302 and a water inlet 303 are sequentially arranged on one side of the bottom of the water tank 301, and the acetone solution can be discharged and poured through the drain port 302 and the water inlet 303. A water storage member 304 is installed inside the water tank 301. At the same time, a buoyancy member 305 is also arranged inside the water tank 301. The buoyancy member 305 is installed on one side of the water storage member 304, and a switch member 306 is also installed on the outside of the water storage member 304.

[0086] Furthermore, the water storage member 304 includes a water tank 304a for storing acetone solution, the bottom of the water tank 304a is connected to a connecting pipe 304b connected to the inside of the water tank 301, and the upper outer portion of the water tank 304a is also connected to a flushing pipe 304c. When the water tank 301 contains acetone solution, the flushing pipe 304c is completely immersed in the solution, and the inside is filled with acetone solution, and the pipe mouth of the flushing pipe 304c is lower than the liquid level of the water tank 304a. Therefore, when the solution in the water tank 301 is emptied and the flushing pipe 304c is opened, the solution in the water tank 304a can flow out from the flushing pipe 304c according to the siphon principle, and the residual photoresist attached to the micro-hotplate can be flushed, thereby solving the problem that the photoresist is still attached to the surface of the micro-hotplate after separation, and preventing the photoresist from remaining on the surface and affecting the normal removal and use of the micro-hotplate.

[0087] The buoyancy member 305 includes a float ball 305a which is hollow and filled with gas. The float ball 305a can always float on the liquid surface of the water tank 301 under the action of its own buoyancy, and the bottom of the float ball 305a is fixedly provided with a first float rod 305b and a second float rod 305c in sequence. The first float rod 305b is vertically downwardly arranged, while the second float rod 305c is bent and extends upwardly. In addition, a push groove 305d is left on the first float rod 305b and the second float rod 305c, and one end of the push groove 305d is connected to a straight groove 305e. At the same time, a switch member 306 is provided at the end of the first float rod 305b and the second float rod 305c.

[0088] The switch member 306 includes a fixed plate 306a installed on the outside of the water tank 304a, and the surface of the fixed plate 306a is rotatably coaxially matched with a rotating plate 306b, and a push column 306c is integrally arranged on the inner wall of the rotating plate 306b, and a guide groove 306d is also reserved on the bottom surface of the rotating plate 306b, and guide balls 306e are symmetrically embedded in the guide groove 306d. At the same time, the bottoms of the two guide balls 306e are fixedly connected with clamping plates 306f, and the other ends of the clamping plates 306f are fitted with the outer wall of the connecting pipe 304b, and the bottom surfaces of the two clamping plates 306f are also integrally provided with positioning blocks 306g, and positioning grooves 306h cooperating with the two positioning blocks 306g are symmetrically opened on the fixed plate 306a, and the positioning blocks 306g are movably embedded in the inside of the positioning grooves 306h, so that the movement trajectory of the clamping plates 306f can be guided by the positioning grooves 306h to ensure the subsequent normal use of the clamping plates 306f.

[0089] Preferably, the push groove 305d is arranged in an inclined spiral on the outer wall of the first float rod 305b and the second float rod 305c, and the push column 306c on the inner wall of the rotating disk 306b is movably embedded in the push groove 305d. Therefore, when the float 305a begins to move downward due to the buoyancy, the push block can be squeezed by the push groove 305d, so that the push block can quickly respond and slide inside the push groove 305d. Under the spiral setting of the push groove 305d, the rotating disk 306b can rotate synchronously with the downward movement of the float 305a, thereby realizing the subsequent control of the movement of the splint 306f.

[0090] The guide groove 306d is arranged in an elliptical ring shape, and the two guide balls 306e can slide inside it. It should be noted that the two guide balls 306e are initially located on both sides of the long axis end of the elliptical guide groove 306d, so that when the rotating disk 306b rotates 90°, the movement restriction of the two clamping plates 306f is achieved by the cooperation of the positioning groove 306h and the positioning block 306g. At this time, the two guide balls 306e can be pushed by the guide groove 306d and the relative position between them and the guide groove 306d changes, that is, the guide balls 306e move from the long axis end of the guide groove 306d to the guide groove 306d. 6d short axis end, thereby changing the distance between the guide ball 306e and the center of the guide groove 306d, realizing the synchronous movement of the two clamping plates 306f toward the direction of the connecting pipe 304b, and the connecting pipe 304b can be clamped off by the clamping plate 306f to achieve the purpose of sealing the bottom of the water tank 301. When the solution in the water tank 301 just starts to be emptied, the connecting pipe 304b at the bottom of the water tank 304a can be quickly shut off by the switch part 306, thereby minimizing the drop of the water level in the water tank 304a as the solution in the water tank 301 is discharged, thereby ensuring the normal use of the flushing pipe 304c.

[0091] It should be noted that the switch member 306 located at the end of the second float rod 305c is initially in a clamping state to close the flushing tube 304c, that is, the corresponding guide balls 306e on the second float rod 305c are located on both sides of the short axis end of the guide groove 306d, so that when the second float rod 305c descends with the float ball 305a, the guide balls 306e can move to both sides of the long axis end on the guide groove 306d as the rotating disk 306b rotates through the cooperation between the push groove 305d and the push column 306c, so that the two clamping plates 306f move outward toward each other, thereby releasing the clamping of the flushing tube 304c and opening the flushing tube 304c to flush the micro-hot plate.

[0092] The outer side of the fixed plate 306a is also connected to a swing member 308, and the swing member 308 includes a swing rod 308b with one end fixed to the outer wall of the cleaning tank 307, and a positioning seat 308a is movably connected to the middle section of the swing rod 308b, and the positioning seat 308a is fixed to the water tank 304a. At the same time, a connecting block 308c is fixedly provided at one end of the swing rod 308b close to the first float rod 305b.

[0093] The outer wall of the first floating rod 305b is provided with a pushing surface 305f, and the pushing surface 305f is arranged in a corrugated shape. At the same time, a connecting groove 305g is reserved on the pushing surface 305f. The connecting block 308c at the front end of the swing rod 308b is movably embedded in the connecting groove 305g and can slide inside the connecting groove 305g. Therefore, when the first floating rod 305b moves downward, the relative position between the swing rod 308b and the first floating rod 305b changes, and the pushing surface 305f on the outer side of the first floating rod 305b pushes the swing rod 308b to reciprocate on the horizontal plane, and under the positioning of the positioning seat 308a, the swing of the swing rod 308b is realized, thereby allowing the cleaning tank 307 to swing back and forth in the solution, enhancing the convection between the cleaning tank 307 and the solution, and the outer wall of the cleaning tank 307 is evenly provided with sieve holes 307a, thereby impurities such as fallen photoresist can be sieved out by the sieve holes 307a, so that the subsequent removal of the micro-hotplate is more convenient.

[0094] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to several modifications still falling within the scope of the appended claims.

[0095] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0096] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0097] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A corrosion-resistant and highly reliable MEMS gas sensor, characterized in that: include, A housing structure (100) comprising a sensor housing (101), a welding pad (102) located on the inner wall of the sensor housing (101), a gas permeable area (T) located on the top of the sensor housing (101), and an anti-corrosion filter membrane (103) located on the gas permeable area (T); and, A micro-hotplate mechanism (200) comprises a sensor substrate (201) arranged inside a sensor housing (101), a first insulating medium layer (202) located on the surface of the sensor substrate (201), a Pt heating electrode (203) located on the surface of the first insulating medium layer (202), a second insulating medium layer (204) located on the surface of the Pt heating electrode (203), and an Au test electrode (205) located on the surface of the second insulating medium layer (204); The sensor substrate (201) comprises a buried oxide layer (201a) and a Si substrate layer (201b), wherein the Si substrate layer (201b) is arranged at the bottom of the buried oxide layer (201a); A sensitive area (M) is provided on the Au test electrode (205).

2. The method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to claim 1, characterized in that: include, stacking the buried oxide layer (201a) and the substrate layer as a base; Pre-treating the substrate; Placing the substrate in an LPCVD device and introducing a mixed gas to decompose the mixed gas and deposit a first insulating dielectric layer (202) on the surface of the substrate; A layer of hexamethyldisilazane (HMDS) is covered on the surface of the first insulating dielectric layer (202); performing photolithography on the substrate surface; Sputtering a Pt film on the surface of the silicon wafer, and immersing the silicon wafer in an immersion mechanism (300) containing an acetone solution, and finally retaining a Pt heating electrode (203) on the surface of the silicon wafer; Placing the substrate in a PECVD device and introducing a mixed gas to decompose the mixed gas and deposit a second insulating dielectric layer (204) on the surface of the substrate; Continue to perform conversion photolithography on the second insulating dielectric layer (204); Sputtering a layer of Au thin film on the surface of the silicon wafer, immersing the silicon wafer in acetone, and finally retaining an Au test electrode (205) on the surface of the silicon wafer; The surface of the substrate layer is photolithographically processed, and then the substrate layer is deeply etched with bulk silicon to produce a MEMS gas sensor.

3. The method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to claim 1 or 2, characterized in that: The soaking mechanism (300) comprises a water tank (301), a water outlet (302) and a water inlet (303) are sequentially arranged on one side of the bottom of the water tank (301), a water storage component (304) is arranged inside the water tank (301), a buoyancy component (305) is also arranged inside the water tank (301), the buoyancy component (305) is arranged on one side of the water storage component (304), and a switch component (306) is arranged on the outside of the water storage component (304).

4. The method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to claim 3, characterized in that: The water storage member (304) comprises a water tank (304a), a connecting pipe (304b) is arranged at the bottom of the water tank (304a), and a flushing pipe (304c) is also arranged on the outside of the water tank (304a).

5. The method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to claim 4, characterized in that: The buoyancy member (305) comprises a floating ball (305a), and a first floating rod (305b) and a second floating rod (305c) are sequentially arranged on the outer side of the floating ball (305a), and a push groove (305d) is reserved on the outer wall of the first floating rod (305b) and the second floating rod (305c), and one end of the push groove (305d) is connected to a straight groove (305e).

6. The method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to claim 5, characterized in that: The switch component (306) comprises a fixed disk (306a) installed on the outside of the water tank (304a), a rotating disk (306b) is rotatably provided on the surface of the fixed disk (306a), a push column (306c) is fixedly provided on the inner wall of the rotating disk (306b), a guide groove (306d) is also reserved on the bottom surface of the rotating disk (306b), guide balls (306e) are symmetrically embedded in the guide groove (306d), the bottoms of the two guide balls (306e) are each provided with a clamping plate (306f), the bottom surfaces of the clamping plates (306f) are each provided with a positioning block (306g), and positioning grooves (306h) are symmetrically provided on the fixed disk (306a).

7. The method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to claim 6, characterized in that: The push groove (305d) is arranged in an inclined spiral along the outer wall of the first floating rod (305b), and the push groove (305d) and the push column (306c) are in sliding fit.

8. The method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to claim 7, characterized in that: The clamping plate (306f) and the rotating disk (306b) form a linkage structure through a guide groove (306d), and the guide groove (306d) is arranged in an elliptical ring shape.

9. The method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to claim 8, characterized in that: The outer wall of the first floating rod (305b) is provided with a pushing surface (305f), and a connecting groove (305g) is left on the pushing surface (305f); The pushing surface (305f) is arranged in a corrugated manner.

10. The method for preparing a corrosion-resistant and highly reliable MEMS gas sensor according to claim 9, characterized in that: The outer wall of the cleaning tank (307) is evenly provided with sieve holes (307a); The outer side of the switch member (306) is also connected to a swing member (308), and the swing member (308) includes a swing rod (308b), a positioning seat (308a) is arranged on the middle section of the swing rod (308b), and a connecting block (308c) is arranged at the end of the swing rod (308b).

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