Preparation Method and Application of a Silicon-Based MEMS Gas Sensor Chip

Abstract

The present invention discloses a preparation method and application of a silicon-based MEMS gas sensor chip, including: S1, depositing an insulating material on the upper surface of a silicon wafer substrate to obtain a cantilever support layer; S2, depositing a metal at the wafer level on the surface of the cantilever support layer to form a heating electrode; S3, depositing an insulating layer at the wafer level on the surface of the heating electrode; S4, fabricating an etching window and a test electrode at the wafer level on the surface of the insulating layer; S5, depositing an adhesive layer at the wafer level on the surface of the test electrode; S6, fabricating a gas-sensitive thin film integrally on the surface of the adhesive layer; S7, introducing an etching solution at the etching window, and performing wet etching on the silicon wafer substrate below the region where the gas-sensitive thin film is located to obtain a gas sensor wafer; S8, performing dicing on the gas sensor wafer to obtain a silicon-based MEMS gas sensor chip; wherein, the adhesive layer and the gas-sensitive thin film are made of the same material. The gas sensor chip obtained by the present invention has excellent gas-sensing properties such as high stability and high sensitivity, and realizes the compatible manufacturing of a silicon-based gas-sensitive thin film.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas detection, and more specifically, relates to a preparation method and application of a silicon-based MEMS gas sensor chip. Background Art

[0002] Metal oxide semiconductor thin film gas sensors have the advantages of high sensitivity and fast response speed, and have been widely used in the fields of industrial safety, biomedicine, smart cities, etc. With the advent of the post-Moore era and the proposal of the "More than Moore" concept, new intelligent sensors for all-round intelligent sensing have become an important development direction. As an important part of intelligent sensors, gas sensors will further develop towards miniaturization, low power consumption, and integration.

[0003] In the traditional preparation method of silicon-based MEMS gas sensor chips, the prepared gas-sensitive material is usually transferred to the surface of the silicon-based device by brushing or drop coating. This step requires single-device operation, with high cost, low efficiency, and inability to perform photolithographic patterning, so it is difficult to achieve batch production of sensors. In addition, due to the uneven thickness and density of the thin film, the specific surface area of the material varies greatly in different regions of the same device and between different devices, affecting the stability and consistency of the sensor. Summary of the Invention

[0004] Aiming at the above defects or improvement requirements of the prior art, the present invention provides a preparation method and application of a silicon-based MEMS gas sensor chip to solve the technical problem of poor stability of the silicon-based MEMS gas sensor chip prepared by the prior art.

[0005] To achieve the above object, in the first aspect, the present invention provides a preparation method of a silicon-based MEMS gas sensor chip, including the following steps:

[0006] S1. Deposit an insulating material on the upper surface of the silicon wafer substrate to form a cantilever support layer covering the silicon wafer substrate;

[0007] S2. Deposit a metal at the wafer level on the surface of the above cantilever support layer to form a heating electrode;

[0008] S3. Deposit an insulating layer at the wafer level on the surface of the above heating electrode to cover the cantilever support layer and the heating electrode with the insulating layer;

[0009] S4. Prepare a corrosion window and a test electrode at the wafer level on the surface of the above insulating layer; wherein, the corrosion window is located around the heating electrode and penetrates through the insulating layer and the cantilever support layer; the test electrode is located directly above the heating electrode;

[0010] S5. Deposit an adhesive layer at the wafer level on the surface of the above test electrode;

[0011] S6. Integrally prepare a gas-sensitive thin film on the surface of the above-mentioned bonding layer;

[0012] S7. Introduce an etching solution at the above-mentioned etching window, and perform wet etching on the silicon wafer substrate below the area where the gas-sensitive thin film is located to obtain a gas sensor wafer;

[0013] S8. Perform dicing on the gas sensor wafer to obtain a silicon-based MEMS gas sensor chip;

[0014] Among them, the material of the bonding layer is the same as that of the gas-sensitive thin film.

[0015] Further preferably, the insulating material is an oxide or a nitride or a mixture of the two.

[0016] Further preferably, the insulating material is an ONO composite film.

[0017] Further preferably, the material of the heating electrode is titanium-platinum metal.

[0018] Further preferably, the test electrode is an interdigital electrode or a comb-shaped electrode.

[0019] Further preferably, step S7 includes: performing wet etching at the above-mentioned etching window so that the silicon wafer substrate below the area where the gas-sensitive thin film is located is completely etched, thereby releasing the cantilever.

[0020] In a second aspect, the present invention provides a silicon-based MEMS gas sensor chip, which is prepared by using the preparation method of the silicon-based MEMS gas sensor chip provided in the first aspect of the present invention.

[0021] In a third aspect, a silicon-based MEMS gas sensor chip includes gas sensors arranged in an array; the gas sensor includes a silicon wafer substrate unit, a cantilever support unit, a heating electrode, an insulating layer, a test electrode, a bonding layer, and a gas-sensitive thin film that are sequentially distributed from bottom to top;

[0022] Among them, the material of the bonding layer is the same as that of the gas-sensitive thin film; there are pits in the area of the silicon wafer substrate unit below the area where the gas-sensitive thin film is located; the cantilever support unit is a cantilever structure and is fixed above the pit through a cantilever beam.

[0023] Generally speaking, through the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

[0024] 1. The present invention provides a method for fabricating a silicon-based MEMS gas sensor chip. After patterning and integrally fabricating a gas-sensitive thin film, a cantilever is then released by wet etching to complete the wafer-level integration of the gas-sensitive thin film and the device. Preparing the gas-sensitive thin film on a complete wafer can ensure uniform particle distribution, consistent film thickness, and specific surface area among different devices, significantly improving the consistency and working stability of the sensor.

[0025] 2. In the method for fabricating a silicon-based MEMS gas sensor chip provided by the present invention, a bonding layer made of the same material as the gas-sensitive thin film is prepared between the test electrode and the gas-sensitive thin film. The strong intermolecular interaction force of the same material is used to replace the traditional weak physical contact, and the corrosion resistance of the gas-sensitive thin film is improved by strengthening the interfacial bonding force, avoiding film peeling caused by subsequent chemical corrosion. This enables the gas-sensitive thin film to be prepared before the release of the cantilever structure and remain unaffected by subsequent processes, maintaining its highly sensitive gas-sensing performance.

[0026] 3. Compared with the traditional method of transferring materials for individual devices, the method for fabricating a silicon-based MEMS gas sensor chip provided by the present invention has the advantages of high efficiency and batch production in wafer-level preparation of the gas-sensitive thin film. In addition, the sensor prepared by this method has the potential for wafer-level packaging, and the device size can be further reduced in the future to lower the manufacturing cost.

[0027] 4. In the method for fabricating a silicon-based MEMS gas sensor chip provided by the present invention, the thin film preparation processes used in each step are all mature semiconductor processes, providing a development direction for the future process integration of MEMS gas sensors and integrated circuits, such as signal processing circuits, temperature modulation circuits, measurement, and data, and expanding the research ideas of intelligent sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flowchart of a method for fabricating a silicon-based MEMS gas sensor chip provided in Embodiment 1 of the present invention;

[0029] Figure 2 It is a schematic diagram of depositing a cantilever support layer on a silicon wafer provided in Embodiment 1 of the present invention;

[0030] Figure 3 It is a schematic diagram of fabricating a heating electrode provided in Embodiment 1 of the present invention;

[0031] Figure 4 It is a schematic diagram of depositing an insulating layer provided in Embodiment 1 of the present invention;

[0032] Figure 5 It is a schematic diagram of etching a corrosion window provided in Embodiment 1 of the present invention;

[0033] Figure 6Schematic diagram of the deposition test electrode provided in Embodiment 1 of the present invention;

[0034] Figure 7 Schematic diagram of the deposition bonding layer provided in Embodiment 1 of the present invention;

[0035] Figure 8 Schematic diagram of the preparation of the gas-sensitive thin film provided in Embodiment 1 of the present invention;

[0036] Figure 9 Schematic diagram of the formation of a cantilever beam structure by wet etching of bulk silicon provided in Embodiment 1 of the present invention;

[0037] Figure 10 Schematic diagram of the structure of a silicon-based MEMS gas sensor chip provided in Embodiment 3 of the present invention;

[0038] Figure 11 Schematic diagram of the structure of the gas sensor provided in Embodiment 3 of the present invention;

[0039] Figure 12 Schematic diagram of the silicon wafer substrate provided in Embodiment 3 of the present invention;

[0040] Figure 13 Schematic diagram of the cantilever support layer provided in Embodiment 3 of the present invention;

[0041] Figure 14 Schematic diagram of the heating electrode provided in Embodiment 3 of the present invention;

[0042] Figure 15 Schematic diagram of the insulating layer provided in Embodiment 3 of the present invention;

[0043] Figure 16 Schematic diagram of the test electrode provided in Embodiment 3 of the present invention. Detailed implementation manners

[0044] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] Embodiment 1

[0046] A method for preparing a silicon-based MEMS gas sensor chip, as Figure 1 shown, includes the following steps:

[0047] S1. Deposit an insulating material on the upper surface of the silicon wafer substrate to form a cantilever support layer covering the silicon wafer substrate;

[0048] Specifically, as Figure 2 shown, a cantilever support layer 2 is prepared on the surface of a substrate silicon wafer 1. The insulating material can be an oxide, a nitride, or a mixture of the two, preferably an ONO composite film. In this embodiment, a 4-12 inch silicon wafer is used as the substrate, and a silicon oxide, silicon nitride, or composite film support layer (with a total thickness of 300 nm to 2 μm) is prepared on the substrate by thermal oxidation growth, PECVD, or LPCVD processes.

[0049] S2. Perform wafer-level lithography and deposit metal on the surface of the above-mentioned cantilever support layer to form a heating electrode; wherein, the material of the heating electrode can be a material with good Joule heat efficiency, such as titanium-platinum metal, polysilicon, etc.; in this embodiment, titanium-platinum metal is preferably used;

[0050] Specifically, as Figure 3 shown, a heating electrode 3 (with a central heating area of 10 μm to 300 μm) is prepared on the surface of the cantilever support layer 2. In this embodiment, the lift-off process or the metal etching process is used to deposit titanium / platinum metal (with a thickness of 100 nm to 500 nm), which is used as the heating electrode 3.

[0051] S3. Deposit an insulating layer at the wafer level on the surface of the above-mentioned heating electrode, so that the insulating layer covers the cantilever support layer and the heating electrode;

[0052] Specifically, the preparation process of the insulating layer is as Figure 4 shown, an insulating layer 4 (with a thickness of 200 nm to 600 nm) is prepared above the heating electrode 3. In this embodiment, a silicon nitride or silicon oxide insulating layer is deposited by the PECVD or LPCVD process, and the surface is planarized by a CMP device.

[0053] S4. Prepare an etching window and a test electrode at the wafer level on the surface of the above-mentioned insulating layer; wherein, the etching window is located around the heating electrode and penetrates through the insulating layer and the cantilever support layer; the test electrode is located directly above the heating electrode;

[0054] Specifically, as Figure 5 shown, a lithography and dry etching process is used to prepare an etching window (with an etching window size of 100 μm to 500 μm) on the surface of the insulating layer 4. In this embodiment, first, the lithography process is used to define the size, shape, and formation position of the cantilever structure etching window, and then the dry etching process such as RIE or ICP is used to remove the insulating layer 4 and the cantilever support layer 2 at the corresponding position of the cantilever structure etching window, so that the silicon at the cantilever structure etching window position is exposed on the upper surface, facilitating the subsequent wet etching to complete the release of the cantilever structure. Among them, there are no restrictions on the opening size, the number of windows, and the shape of the etching window.

[0055] As Figure 6As shown, a test electrode 5 (the area of the test electrode region is 10 um to 300 um) is formed by photolithography and depositing metal on the surface of the insulating layer 4. In this embodiment, the lift-off process or the metal etching process is used to deposit metals such as titanium / platinum, titanium / gold, chromium / gold, etc. (the thickness is 100 nm to 500 nm) to be used as the test electrode 5. The test electrode in this embodiment is an electrode with high detection sensitivity, such as an interdigital electrode or a comb-shaped electrode.

[0056] S5. Deposit a bonding layer on the surface of the above test electrode at the wafer level;

[0057] Specifically, as Figure 7 shown, a bonding layer 6 (the area of the bonding layer is 10 um to 300 um, and the thickness is 6 nm to 200 nm) is prepared on the surface of the test electrode 5. In this embodiment, the lift-off process is used for the deposition and patterning of the bonding layer as the base material for subsequent deposition of the gas-sensitive film 7.

[0058] S6. Prepare a gas-sensitive film integrally on the surface of the above bonding layer; the area of the gas-sensitive film is the same as that of the bonding layer.

[0059] Specifically, as Figure 8 shown, a gas-sensitive film 7 (the area of the gas-sensitive film is 10 um to 300 um, and the thickness is 20 nm to 500 nm) is prepared on the surface of the bonding layer 6. In this embodiment, photolithographic patterning, combined with magnetron sputtering and high-temperature sintering processes, is used for the deposition and patterning of the gas-sensitive film 7 to achieve the sensing function of the gas sensor.

[0060] It should be noted that by preparing a bonding layer made of the same material as the gas-sensitive film between the test electrode and the gas-sensitive film, the interfacial bonding force between the two is improved, the performance of the base of the gas-sensitive film is strengthened, so that the gas-sensitive film can be prepared before releasing the cantilever structure and is not affected by subsequent processes, maintaining its high-sensitivity gas-sensitive performance. The material of the bonding layer is the same as that of the gas-sensitive film (it can be materials such as indium oxide, tin oxide, etc.), which has a better interfacial bonding force with the gas-sensitive film and does not affect the semiconductor properties of the gas-sensitive film.

[0061] S7. After introducing an etching solution at the above corrosion window and wet-etching the silicon wafer substrate below the region where the gas-sensitive film is located, the gas-sensitive film, the bonding layer, the test electrode, the insulating layer, the heating electrode, the cantilever support layer, and the silicon wafer substrate together form a gas sensor wafer;

[0062] Specifically, as Figure 9As shown, a cantilever structure is prepared by wet etching in the corresponding area of the etching window. Optionally, wet etching is performed at the above-mentioned etching window so that the silicon wafer substrate below the area where the gas-sensitive film is located is completely etched, thereby releasing the cantilever. In this embodiment, an etching solution such as KOH or TMAH is immersed in the corresponding area of the etching window of the cantilever structure, and anisotropic wet etching is performed on the bulk silicon in the central area of the substrate silicon wafer 1, and the upper cantilever support layer 2, heating electrode 3, insulating layer 4, test electrode 5, bonding layer 6, and gas-sensitive film 7 structures are completely released to form a suspended structure supported by four cantilever beams.

[0063] It should be noted that the above Figures 2 - 9 are all illustrated by taking one gas sensor on a silicon-based MEMS gas sensor chip as an example (the preparation of each gas sensor is carried out simultaneously and the processes are the same). During the preparation process, multiple silicon-based MEMS gas sensor chips can be prepared on one silicon wafer substrate at the same time.

[0064] S8. The gas sensor wafer is sliced to obtain a silicon-based MEMS gas sensor chip;

[0065] Specifically, after the gas sensor wafer is prepared, a silicon-based MEMS gas sensor chip is formed by using processes such as slicing and packaging. The gas sensor wafer can be first divided and cut, and then the obtained gas sensor array is packaged to obtain a silicon-based MEMS gas sensor chip; or the gas sensor wafer can be first packaged as a whole and then sliced and divided to obtain a silicon-based MEMS gas sensor chip; this method of packaging first and then cutting can obtain a smaller size, greatly improve the quality of the silicon-based MEMS gas sensor chip, and the chips have good consistency.

[0066] Traditional gas sensors such as thick film sensors often have high stability, but their structures are too dense and the sensitivity is insufficient; while thin film sensors are often porous and have high sensitivity, but the interfacial bonding force is insufficient, the preparation process is not mature, and they cannot be mass-produced, resulting in poor stability. The present invention can realize the preparation of a high-stability and high-sensitivity sensor chip by depositing a bonding layer and a gas-sensitive film, realize the effective integration of a semiconductor gas-sensitive film and a silicon-based MEMS device, and at the same time maintain the excellent gas-sensing performance of the semiconductor gas-sensitive film with high sensitivity and fast response, as well as the excellent advantages of the silicon-based MEMS device such as small size, easy integration, low power consumption, low cost, and high stability. The obtained gas sensor chip has excellent gas-sensing performances such as high stability and high sensitivity, and realizes the compatible manufacturing of a silicon-based gas-sensitive film.

[0067] Embodiment 2

[0068] A silicon-based MEMS gas sensor chip is prepared by using the preparation method of the silicon-based MEMS gas sensor chip provided in Embodiment 1.

[0069] The related technical solutions are the same as those in Embodiment 1 and will not be elaborated here.

[0070] Embodiment 3

[0071] As Figure 10 shown, a silicon-based MEMS gas sensor chip includes gas sensors arranged in an array; the gas sensor includes a silicon wafer substrate unit, a cantilever support unit, a heating electrode, an insulating layer, a test electrode, a bonding layer, and a gas-sensitive thin film distributed in sequence from bottom to top;

[0072] Among them, the topmost layer is the gas-sensitive thin film; the redox reaction that occurs on the surface of the gas-sensitive thin film before and after gas adsorption causes a change in its conductivity; based on this semiconductor property, the gas-sensitive thin film is used to convert the change in target gas information into a change in its own conductivity; among them, the target gas information includes the type and / or concentration of the target gas. Specifically, the material of the gas-sensitive thin film can be an N-type semiconductor, a P-type semiconductor, etc.

[0073] The material of the bonding layer is the same as that of the gas-sensitive thin film, which is used to improve the interfacial bonding force of the gas-sensitive thin film and prevent the gas-sensitive thin film from falling off during subsequent processes. In addition, since the material selection of the bonding layer is the same as that of the gas-sensitive thin film, it does not affect the semiconductor properties of the gas-sensitive thin film.

[0074] The test electrode is used to read the change in the conductivity of the gas-sensitive thin film before and after the adsorption of the target gas by using two electrodes, so as to obtain the target gas information; preferably, the test electrode can be an interdigital electrode.

[0075] The material of the heating electrode is preferably titanium-platinum metal, which is used to provide the working temperature required by the gas sensor by using the Joule heat effect of the metal electrode.

[0076] The insulating layer is located between the test electrode and the heating electrode, which is used to isolate the electrical connection between the heating electrode and the test electrode, avoid signal crosstalk between the heating voltage and the positive and negative poles of the test electrode, and affect the transmission of the heating and detection signals of the sensor.

[0077] There are pits in the area of the silicon wafer substrate unit below the area where the gas-sensitive thin film is located; the cantilever support unit is a cantilever structure, which is fixed above the pits through a cantilever beam, and is used to support the upper heating electrode, insulating layer, test electrode, bonding layer, and gas-sensitive thin film to prevent structural collapse and cantilever fracture. By forming a cantilever structure, the heat conduction loss can be greatly reduced, and the measurement accuracy of the gas sensor can be improved. The material of the cantilever support unit is an insulating material, specifically it can be an oxide or a nitride or a mixture of the two, preferably an ONO composite film.

[0078] It should be noted that the silicon-based MEMS gas sensor chip in this embodiment can be prepared by the preparation method of the silicon-based MEMS gas sensor chip described in Embodiment 1. The silicon wafer substrate described in Embodiment 1 includes multiple silicon wafer substrate units, and the silicon wafer substrate unit is the smallest unit of the silicon wafer substrate. Similarly, the cantilever support layer described in Embodiment 1 includes multiple cantilever support units, and the cantilever support unit is the smallest unit of the cantilever support layer. Multiple silicon-based MEMS gas sensor chips are batch-prepared by the preparation method of the silicon-based MEMS gas sensor chip described in Embodiment 1. Each silicon wafer substrate unit in each silicon-based MEMS gas sensor chip jointly constitutes the silicon wafer substrate described in Embodiment 1. Each cantilever support unit in each silicon-based MEMS gas sensor chip jointly constitutes the cantilever support layer described in Embodiment 1.

[0079] Specifically, as Figure 11 shown, in an alternative embodiment, the gas sensor includes: a silicon wafer substrate unit 1', a cantilever support unit 2', a heating electrode 3, an insulating layer 4, a test electrode 5, an adhesive layer 6, and a gas-sensitive film 7.

[0080] The silicon wafer substrate unit 1' is a silicon-based MEMS gas sensor substrate compatible with the semiconductor gas-sensitive film, which is a part of the silicon wafer substrate and its smallest unit, and its material is silicon. As Figure 12 shown, the pit in the central area of the silicon wafer substrate unit 1' is a suspended area formed by wet etching. Above the suspended area is a cantilever beam structure etched from the cantilever support unit 2'.

[0081] The cantilever support unit 2' is disposed above the substrate silicon wafer 1. It should be noted that there are no restrictions on the opening size, number, and shape of the corrosion windows. The formation position of the central support area formed by the corrosion windows corresponds to the suspended area of the substrate silicon wafer 1. In this embodiment, as Figure 13 shown, there are four corrosion windows evenly surrounded around the outside of the central position, serving as the windows for wet etching of the four-cantilever structure. The cantilever structure formed by the four corrosion windows is used to support the heating electrode 3, insulating layer 4, test electrode 5, adhesive layer 6, and gas-sensitive film 7 above.

[0082] The heating electrode 3 is disposed above the cantilever support unit 2'. As Figure 14 shown, the heating electrode 3 includes a central heating area 31; a rectangular lead area 32 is respectively disposed at the diagonal corners of the central heating area (there are two rectangular lead areas in total); by applying a voltage to both ends of the heating electrode 3, a certain working temperature is provided for the gas-sensitive film 7 above the central heating area. There are no restrictions on the shapes of the central heating area and the lead area, and the size and formation position correspond to the central support area formed by the corrosion windows of the cantilever support unit 2'.

[0083] The insulating layer 4 is disposed above the cantilever support layer 2 and the heating electrode 3 and is in direct contact with both of them. As Figure 15 shown, in this embodiment, there are four windows in the central insulating region, which also serve as the windows for wet etching of the four-cantilever structure. The enclosed central insulating region is used to isolate the heating electrode 3 below and the test electrode 5 above. The opening size, shape, and formation position of the central insulating region of the insulating layer 4 are the same as those of the cantilever support unit 2'.

[0084] The test electrode 5 is disposed above the insulating layer 4. As Figure 16 shown, the test electrode 5 includes a central test region 51; a rectangular lead region 52 is respectively disposed at the diagonal corners of the central test region (there are two rectangular lead regions in total); the central test region is in contact with the upper bonding layer 6 for transmitting the resistance signal of the gas-sensitive film 7. There are no restrictions on the size and shape of the central test region and the lead region, and the formation position corresponds to the cantilever structure formed by the insulating layer 4 and the cantilever support unit 2'.

[0085] The bonding layer 6 is disposed between the test electrode 5 and the gas-sensitive film 7. The bonding layer 6 is prepared on the central test region of the test electrode 5 and is directly connected to the test electrode. As the base material of the gas-sensitive film 7, it prevents it from falling off due to the wet etching process. The material selection of the bonding layer 6 is consistent with that of the gas-sensitive film 7, and the size and formation position correspond to the central test region of the test electrode 5.

[0086] The gas-sensitive film 7 is disposed above the bonding layer 6. The gas-sensitive film 7 is prepared on the bonding layer 6 and uses the change in conductivity to identify the type and concentration of gases. There are no restrictions on the gas-sensitive characteristics of the gas-sensitive film 7, and the size and formation position correspond to the bonding layer 6.

[0087] Furthermore, in this embodiment, the silicon-based MEMS gas sensor chip includes the above gas sensor and can be composed of an array arrangement of multiple gas sensors, where at least one is a gas sensor compatible with the semiconductor gas-sensitive film provided by the present invention.

[0088] It should be noted that there are no restrictions on the array quantity, arrangement method, and distribution position of the gas sensors in the silicon-based MEMS gas sensor chip. There are no restrictions on the subsequent electrode lead-out method of the gas sensor described in the embodiments of the present invention included in the silicon-based MEMS gas sensor chip compatible with the semiconductor gas-sensitive film, and it can be TSV packaging, wire bonding packaging, etc.

[0089] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation method of a silicon-based MEMS gas sensor chip, characterized in that It includes the following steps: S1. Deposit an insulating material on the upper surface of the silicon wafer substrate to form a cantilever support layer covering the silicon wafer substrate; S2. Deposit a metal on the surface of the cantilever support layer at the wafer level to form a heating electrode; S3. Deposit an insulating layer on the surface of the heating electrode at the wafer level so that the insulating layer covers the cantilever support layer and the heating electrode; S4. Prepare a corrosion window and a test electrode on the surface of the insulating layer at the wafer level; The corrosion window is located around the heating electrode and penetrates through the insulating layer and the cantilever support layer; the test electrode is located directly above the heating electrode; S5. Deposit an adhesive layer on the surface of the test electrode at the wafer level; S6. Photolithographically prepare a gas-sensitive thin film integrally on the surface of the adhesive layer; S7. Introduce a corrosion liquid at the corrosion window to perform wet etching on the silicon wafer substrate below the area where the gas-sensitive thin film is located, so that the silicon wafer substrate below the area where the gas-sensitive thin film is located is completely etched, thereby releasing the cantilever to obtain a gas sensor wafer; S8. Perform dicing on the gas sensor wafer to obtain a silicon-based MEMS gas sensor chip, thereby realizing the simultaneous preparation of multiple silicon-based MEMS gas sensor chips on a single silicon wafer substrate; Among them, the material of the adhesive layer is the same as that of the gas-sensitive thin film.

2. The manufacturing method of the silicon-based MEMS gas sensor chip according to claim 1, characterized in that, The insulating material is an oxide or a nitride or a mixture of the two.

3. The manufacturing method of the silicon-based MEMS gas sensor chip according to claim 2, characterized in that, The insulating material is an ONO composite film.

4. The preparation method of the silicon-based MEMS gas sensor chip according to claim 1, wherein, The material of the heating electrode is titanium-platinum metal.

5. The preparation method of the silicon-based MEMS gas sensor chip according to claim 1, characterized in that, The test electrode is an interdigital electrode or a comb-shaped electrode.

6. A silicon-based MEMS gas sensor chip, characterized in that, Prepared by using the preparation method of the silicon-based MEMS gas sensor chip according to any one of claims 1-5.

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