Silicon-based mems gas sensor, array and method of fabrication

Abstract

The application discloses a silicon-based MEMS gas sensor, an array and a preparation method. The silicon-based MEMS gas sensor comprises a silicon wafer base, a detection area and a control electrode area. The detection area comprises four gas-sensitive detection areas. The control electrode area comprises four independent heating electrode pins, four independent test electrode pins, two shared heating electrode pins and two shared test electrode pins. One end of a heating electrode of the gas-sensitive detection area is connected with the independent heating electrode pin, the other end of the heating electrode is connected with a heating electrode of a gas-sensitive detection area adjacent in the vertical direction, and the heating electrodes are commonly connected with one shared heating electrode pin. A test electrode of the gas-sensitive detection area comprises one independent test electrode and one shared test sub-electrode, and the independent test electrode is connected with the independent test electrode pin. Each gas-sensitive detection area is independently controlled in temperature and independently detected in gas sensitivity through the independent heating electrode pin and the test electrode pin. The overall area and structure of the sensor array chip are optimized, the integration degree is the highest, and the area is the smallest.

Description

Technical Field

[0001] This invention belongs to the field of gas detection sensors, and more specifically, relates to a silicon-based MEMS gas sensor, array, and fabrication method. Background Technology

[0002] Due to their high detection sensitivity, ease of detection, low power consumption, and low cost, MEMS (Metal-Oxide-Semiconductor) sensors have been widely used in various gas detection scenarios in recent years. With the rapid development of the Internet of Things (IoT) and Artificial Intelligence (AI), gas identification has become an important application area for gas sensors. Intelligent gas type identification requires the simultaneous acquisition of sensing information by multiple types of MEMS sensors.

[0003] Most current smart gas detection systems acquire diverse sensing information through board-level arraying of sensors. MEMS metal-oxide-semiconductor sensor array chips integrate multiple sensor detection membranes onto a single micro-heating plate, enabling simultaneous detection of target gases by various gas-sensitive materials.

[0004] However, in existing MEMS gas sensors, the heating electrode and detection electrode of each gas detection component are connected in series and controlled by a pair of heating electrodes and test electrodes, making independent temperature control and testing impossible. If each gas detection component is configured with an independent heating electrode and test electrode, it will be limited by the chip size, which limits the number of integrated gas detection components, thereby limiting the amount of information acquired by a single gas sensor and failing to meet the needs of diversified information acquisition. Summary of the Invention

[0005] In view of the shortcomings of related technologies, the present invention aims to provide a silicon-based MEMS gas sensor, array and preparation method, which aims to solve the problems in the field of gas detection where intelligent gas identification cannot independently control temperature and test, and the demand for diversified information acquisition is difficult to meet.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a silicon-based MEMS gas sensor, comprising: a silicon wafer substrate, a detection area disposed above an etched cavity on the silicon wafer substrate, and a control electrode area disposed around the etched cavity;

[0007] The detection area includes four gas-sensitive detection areas arranged in a grid pattern; the control electrode area includes four independent heating electrode pins, four independent test electrode pins, two shared heating electrode pins, and two shared test electrode pins.

[0008] The heating electrode layer of the gas-sensitive detection area includes one heating electrode, and the test electrode layer includes two test electrodes; one end of the heating electrode is connected to an independent heating electrode pin, and the other end is connected to the heating electrode of the gas-sensitive detection area adjacent in the vertical direction, and they are all connected to a common heating electrode pin.

[0009] The gas-sensitive material film of the gas-sensitive detection area is laid flat on two test electrodes; wherein, the test electrode includes an independent test electrode and a common test sub-electrode, forming an interdigitated electrode; four common test sub-electrodes form a complete common test electrode; the independent test electrode is connected to the independent test electrode pin, and the two ends of the common test electrode are connected to the common test electrode pin.

[0010] Each gas-sensitive detection area is independently temperature-controlled via an independent heating electrode pin, and each gas-sensitive detection area is independently gas-sensitive via an independent testing electrode pin.

[0011] Optionally, the heating electrode is strip-shaped and uniformly meanders within the heating electrode layer of the gas-sensitive detection area.

[0012] Optionally, the etched cavity is located at the center of the silicon wafer substrate, and the cantilever support layer of the gas-sensitive detection area includes cantilever beams. Cantilever beams are respectively arranged at the horizontal and vertical axes of symmetry of the gas-sensitive detection area, and the four cantilever beams of the detection area together support the cavity above the silicon wafer substrate to form a suspended structure.

[0013] In a second aspect, the present invention also provides a silicon-based MEMS gas sensor array, the sensor array comprising a plurality of silicon-based MEMS gas sensors as described in any one of the first aspects.

[0014] Thirdly, the present invention also provides a method for fabricating a silicon-based MEMS gas sensor, used to fabricate a silicon-based MEMS gas sensor as described in any of the first aspects, comprising the following steps:

[0015] S1. Deposit insulating material at the wafer level on the surface of a silicon wafer substrate to form a cantilever support layer covering the silicon wafer substrate;

[0016] S2. Deposit metal at the wafer level on the cantilever support layer to form a heating electrode in the detection area and a heating electrode pin in the control electrode area; the detection area includes four gas-sensitive detection areas arranged in a grid pattern; the control electrode area includes four independent heating electrode pins and two shared heating electrode pins; one end of the heating electrode of the gas-sensitive detection area is connected to the independent heating electrode pin, and the other end is connected to the heating electrode of the vertically adjacent gas-sensitive detection area, and they are all connected to a shared heating electrode pin;

[0017] S3. Deposit insulating material at the wafer level on the surface of the heating electrode to form an insulating layer covering the cantilever support layer and the heating electrode;

[0018] S4. Deposit metal at the wafer level on the insulating layer to form test electrodes in the detection area and control electrode area; the control electrode area includes 4 independent test electrode pins and 2 shared test electrode pins; the test electrode includes one independent test electrode and one shared test sub-electrode, forming an interdigitated electrode; the four shared test sub-electrodes form a complete shared test electrode; the independent test electrode is connected to the independent test electrode pin, and the two ends of the shared test electrode are connected to the shared test electrode pin;

[0019] S5. An etching window is formed above each independent heating electrode pin and the common heating electrode pin, the etching window penetrating the insulating layer and exposing the upper surface of the independent heating electrode pin and the common heating electrode pin;

[0020] S6. A corrosion window is formed around the gas-sensitive detection area, and the corrosion window penetrates the insulating layer and the cantilever support layer.

[0021] S7. A gas-sensitive material film is formed for each gas-sensitive detection area by deposition and sputtering; the gas-sensitive material film is laid flat on two test electrodes;

[0022] S8. Perform a dicing process on the silicon-based MEMS gas sensor array fabricated at the wafer level to obtain a single silicon-based MEMS gas sensor.

[0023] Optionally, the cantilever support layer material is an ONO composite material; wherein the thickness of the first silicon oxide layer ranges from 100-200nm, the thickness of the second silicon nitride layer ranges from 300nm-700nm, and the thickness of the third silicon oxide layer ranges from 500nm-1100nm.

[0024] Optionally, the heating electrode is a uniformly meandering metal electrode;

[0025] The insulating layer material is silicon oxide or silicon nitride or a mixture of the two;

[0026] The test electrode package includes an independent test electrode and a shared test sub-electrode, forming an interdigitated electrode; four shared test sub-electrodes constitute a complete shared test electrode.

[0027] The etching solution used in the etching window is tetramethylammonium hydroxide, which forms an etching cavity under the gas-sensitive material film, leaving only the gas-sensitive detection area and the cantilever beam carrying the electrode intact.

[0028] The gas-sensitive material film is a metal oxide semiconductor material with a thickness ranging from 100nm to 800nm.

[0029] The beneficial effects that can be achieved by the above-described technical solutions conceived in this invention compared with the prior art include:

[0030] 1. This invention provides a silicon-based MEMS gas sensor, comprising multiple gas-sensitive detection areas integrated onto an etched pit. Multiple cantilever beams are used to fix these gas-sensitive detection areas, resulting in high space utilization. Since the size of the electrode pin pads often limits the overall area of ​​the sensor array chip, in this invention, the test electrodes on all gas-sensitive detection areas include an independent test electrode and a shared test sub-electrode, forming interdigitated electrodes. Four shared test sub-electrodes constitute a complete shared test electrode, which connects to two shared test electrode pins. This provides a reconfigurable electrode connection method for reference, maximizing the integration of the sensing unit while minimizing its area. This facilitates the optimization of the overall area and structure of the sensor array chip and provides maximum convenience for subsequent wire bonding processes, offering significant advantages in controlling manufacturing costs.

[0031] 2. This invention provides a silicon-based MEMS gas sensor with multiple gas-sensitive detection areas arranged compactly and located on the same pit after wet etching release. This makes the gas detection points more concentrated than those of sensors integrated on the board, resulting in more consistent gas composition during detection. This improves the reliability of gas detection results and ensures the reusability of subsequent gas identification algorithms.

[0032] 3. This invention provides a silicon-based MEMS gas sensor. The serpentine heating electrodes in multiple gas-sensitive detection areas are connected to form independent circuits, which can be controlled by independent voltage input. Different operating temperatures can be provided for the metal oxide semiconductor gas-sensitive materials in each gas detection area. This allows for obtaining gas-sensitive detection data of the same gas-sensitive material at different temperatures, and also ensures that multiple gas-sensitive materials operate at their optimal operating temperatures simultaneously, thus enriching the data volume and providing diversified solutions for intelligent gas identification. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of a silicon-based MEMS gas sensor provided in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the test electrode for fabricating a MEMS gas sensor provided in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the heating electrode for fabricating a MEMS gas sensor provided in an embodiment of the present invention.

[0036] In all the figures, the same reference numerals are used to denote the same elements or structures, wherein: 1 is the silicon wafer substrate, 2 is the etched cavity, 3 is the detection area, 4 is the gas-sensitive detection area, 41 is the heating electrode, 42 is the test electrode, 421 is the independent test electrode, 422 is the common test sub-electrode, pad1 is the independent heating electrode pin, pad2 is the common heating electrode pin, pad3 is the common test electrode pin, and pad4 is the independent test electrode pin. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0038] The following description, in conjunction with a preferred embodiment, illustrates the content involved in the above embodiments.

[0039] Example 1

[0040] like Figure 1 As shown, the structure of a silicon-based MEMS gas sensor, from bottom to top, comprises: a silicon wafer substrate, a cantilever support layer, a heating electrode, an insulating layer, a test electrode, and a gas-sensitive thin film. The silicon wafer substrate 1 has a centrally etched cavity 2, forming a three-dimensional structure. A detection area 3 located above the cavity is supported by multiple cantilever beams, forming a suspended structure. A control electrode area is positioned around the etched cavity 2. The detection area 3 includes four gas-sensitive detection areas 4, each equipped with a uniformly meandering heating electrode 41 and a test electrode 42. The control electrode area includes four independent heating electrode pins, four independent test electrode pins, two shared heating electrode pins (pad 2), and two shared test electrode pins (pad 3).

[0041] like Figure 3 As shown, the first end of the heating electrode 41 of each gas-sensitive detection area 4 is connected to the independent heating electrode pin pad1, and the other end is connected to the heating electrode 41' of the gas-sensitive detection area 4' adjacent in the vertical direction, and they are all connected to a common heating electrode pin pad2.

[0042] A gas-sensitive material film is laid flat on two test electrodes (421 and 422); wherein, the test electrode includes an independent test electrode 421 and a common test sub-electrode 422, and the common test sub-electrode 422 of the four gas-sensitive detection areas constitutes a complete common test electrode. The common test electrode is fishbone shaped and forms interdigitated electrodes with the independent test electrodes of the four gas-sensitive detection areas respectively; the independent test electrodes are connected to the independent test electrode pin pad4, and the two ends of the common test electrode are connected to the common test electrode pin pad3;

[0043] Each gas-sensitive detection area 4 is independently temperature-controlled via an independent heating electrode pin pad1, and each gas-sensitive detection area 4 is independently gas-sensitive via an independent test electrode pin pad4.

[0044] In this embodiment, the silicon-based MEMS gas sensor includes four gas-sensitive detection areas, each rectangular, arranged in a grid pattern to form a large rectangle. This rectangular structure widens the overall width of the cantilever beam, increasing its mechanical strength and reducing the risk of breakage. In one embodiment, such as... Figure 1 As shown, the electrode widths of the heating electrode 41 and the test electrode 42 are approximately 10 μm, and the overall area of ​​the single gas-sensitive detection region formed is approximately 110 μm * 110 μm. The silicon-based MEMS gas sensor has a total of four heating electrodes 41. One end of each heating electrode 41 is individually connected to an independent heating electrode pin pad1 (approximately 150 μm * 150 μm – 200 μm * 200 μm), and the other end is connected to the heating electrode of the vertically adjacent gas-sensitive detection region, and they are all connected to a common heating electrode pin pad2.

[0045] The four gas-sensitive detection zones comprise one common test electrode and four independent test electrodes. Each gas-sensitive detection zone includes two test electrodes: one independent test electrode and one common test sub-electrode, forming an interdigitated electrode. The four common test sub-electrodes constitute a complete common test electrode. The common test electrode (approximately 240µm x 20µm) is fishbone shaped and passes horizontally through the center of each of the four gas-sensitive detection zones, forming interdigitated electrodes with the independent test electrodes of each zone. Each independent test electrode is connected to its independent test electrode pin pad4, and the two ends of the common test electrode are connected to the two common test electrode pins. This design allows the grounding or power supply terminals of multiple heating or test electrodes to be connected on-chip first. This connection method ensures that each gas detection zone can be independently temperature-controlled and independently tested while simplifying the overall structure, maximizing the integration of the sensing unit, minimizing its area, facilitating subsequent bonding processes, and improving process consistency.

[0046] Brownian motion of gas molecules can cause uncontrollable changes in gas composition within a certain space. Therefore, in this embodiment, multiple gas-sensitive detection zones are centrally located, and the high-density integration of gas detection points helps to reduce detection errors caused by changes in gas composition.

[0047] In this embodiment, the shared test electrode is a long, strip-shaped fishbone electrode. Its electrode width is significantly wider than that of the heating electrode and the test electrode, which can reduce resistance, thereby reducing power consumption and improving the energy efficiency of the total power consumption.

[0048] Furthermore, such as Figure 2 As shown, the independent test electrode 421 and the shared test sub-electrode 422 of each gas-sensitive detection area are separated by an opening to form an interdigital electrode, and the gas-sensitive material film is laid flat on the interdigital electrode.

[0049] By fabricating a gas-sensitive thin film on an interdigitated electrode, the surface of the gas-sensitive thin film is in full contact with the electrode, enabling the electrode to quickly detect the resistance change of the gas-sensitive thin film and improving the accuracy and sensitivity of gas detection.

[0050] Optionally, the etched cavity is located at the center of the silicon wafer substrate, and the cantilever support layer of the gas-sensitive detection area includes cantilever beams. Cantilever beams are respectively provided at the horizontal and vertical axes of symmetry of the gas-sensitive detection area, and the detection area is supported by four cantilever beams above the cavity of the silicon wafer substrate to form a suspended structure.

[0051] By integrating multiple gas-sensitive detection areas into a single etching chamber, and arranging four gas-sensitive detection areas within a limited space to form a silicon-based MEMS gas sensor array, this approach achieves higher integration compared to the simple arrangement of multiple traditional MEMS gas sensors to realize the sensor array. It also reduces the overall area of ​​the gas sensor array. Furthermore, in gas sensing, due to the uncertain movement of gas molecules, gas-sensitive detection areas that are closer together will come into contact with gas components more closely, resulting in more reliable gas detection results.

[0052] Furthermore, based on the above embodiments, this application also provides a silicon-based MEMS gas sensor array, which includes multiple gas sensors as described in the above embodiments.

[0053] In the embodiments of this invention, the heating electrodes on all gas-sensitive detection areas are connected in pairs and jointly connected to a common heating electrode pin, reducing the number of heating electrode pins. The test electrodes on all gas-sensitive detection areas include an independent test electrode and a common test sub-electrode, forming interdigitated electrodes. Four common test sub-electrodes constitute a complete common test electrode. The common test electrode connects to two common test electrode pins, reconstructing the electrode connection method and optimizing the overall area and structure of the sensor array chip. This maximizes the integration of the sensing unit while minimizing its area, offering significant advantages in controlling manufacturing costs. Furthermore, each gas-sensitive detection area is equipped with an independent test electrode and heating electrode, allowing each gas-sensitive detection area to perform gas detection independently. Multiple gas-sensitive detection areas, after being released through wet corrosion, are located on the same pit and compactly arranged, resulting in more consistent gas composition during detection, improving the reliability of gas measurement results, and ensuring the reusability of subsequent gas identification algorithms.

[0054] Example 2

[0055] A method for fabricating a silicon-based MEMS gas sensor includes the following steps:

[0056] S1. Deposit insulating material at the wafer level on the surface of a silicon wafer substrate to form a cantilever support layer covering the silicon wafer substrate;

[0057] Specifically, an ONO composite film is deposited on a silicon wafer substrate. First, a silicon oxide layer is prepared by thermal oxidation. Then, a silicon nitride layer is prepared by LPCVD. Finally, a silicon oxide layer is prepared by LPCVD. By taking advantage of the high mechanical strength of silicon nitride and the low thermal conductivity of silicon oxide, the three layers can be combined in a suitable thickness ratio to achieve the good effect of low stress and strain and high peak temperature of heating resistance in a cantilever beam structure. The preferred thicknesses of the three layers are 200 nm, 500 nm, and 1100 nm.

[0058] S2. Metal is deposited at the wafer level on the cantilever support layer, forming a heating electrode in the detection area and a heating electrode pin in the control electrode area. The detection area 3 includes four gas-sensitive detection areas 4, and the control electrode area includes four independent heating electrode pins pad1 and two shared heating electrode pins pad2. One end of the heating electrode 41 of each gas-sensitive detection area 4 is connected to the independent heating electrode pin pad1, and the other end is connected to the heating electrode 41' of the vertically adjacent gas-sensitive detection area 4', and both are connected to a shared heating electrode pin pad2. Figure 3 As shown.

[0059] Specifically, using a lift-off process or a combination of metal etching and photolithography, a heated titanium-platinum metal electrode is sputtered onto the cantilever support layer, with a thickness of approximately 150 nm.

[0060] S3. Deposit insulating material at the wafer level on the surface of the heating electrode to form an insulating layer covering the cantilever support layer and the heating electrode.

[0061] Specifically, an insulating material of silicon oxide or silicon nitride, or a mixture of both, is deposited above the heating electrode using PECVD or LPCVD processes, with a thickness of approximately 500 nm.

[0062] S4. Deposit metal at the wafer level on the insulating layer to form test electrodes in the detection area and control electrode area; the control electrode area includes 4 independent test electrode pins and 2 shared test electrode pins; the test electrode includes one independent test electrode and one shared test sub-electrode, and the shared test sub-electrodes of the four gas-sensitive detection areas constitute a complete shared test electrode. The shared test electrode is fishbone shaped and forms interdigitated electrodes with the independent test electrodes of the four gas-sensitive detection areas respectively; the independent test electrodes are connected to the independent test electrode pins, and the two ends of the shared test electrode are connected to the shared test electrode pins.

[0063] Specifically, a lift-off process or a combination of metal etching and photolithography is used to sputter titanium-platinum metal for test electrodes onto an insulating layer, with a thickness of approximately 150 nm.

[0064] S5. An etching window is formed above each independent heating electrode pin and the common heating electrode pin, the etching window penetrating the insulating layer and exposing the upper surface of the independent heating electrode pin and the common heating electrode pin.

[0065] Specifically, such as Figure 3 As shown, by combining positive photoresist lithography with RIE and ICP etching processes, the insulating layer material above the heating electrode pins pad1 and pad2 is etched through, exposing the heating electrode pins pad1 and pad2, which facilitates subsequent bonding.

[0066] S6. A corrosion window is formed around the gas-sensitive detection area, and the corrosion window penetrates the insulation layer and the cantilever support layer.

[0067] Specifically, by combining positive photoresist lithography with RIE and ICP etching processes, the insulating layer and support layer silicon oxide and silicon nitride materials of the etched area are etched away, exposing the silicon on the wafer substrate. The entire wafer is then placed in the etching solution, and the silicon on the wafer substrate is etched in a directional manner to form an etched cavity, thereby forming a three-dimensional suspended structure cantilever and gas detection area on top.

[0068] S7. A gas-sensitive material film is formed for each gas-sensitive detection area by deposition and sputtering; the gas-sensitive material film is laid flat on the two test electrodes.

[0069] Metal oxide semiconductor gas-sensitive thin films are formed in the gas-sensitive detection area through deposition, sputtering, or other methods. Specifically, magnetron sputtering and ALD are used to deposit the gas-sensitive thin films. The deposition materials can be IGO, CuO, TiO2, etc., with a thickness of approximately 500 nm. A hard mask is used to deposit gas-sensitive thin films on different gas detection areas of the same sensor array, thereby realizing the sensing function. Using a hard mask for gas-sensitive film deposition can...

[0070] S8. Perform a dicing process on the silicon-based MEMS gas sensor array fabricated at the wafer level to obtain a single silicon-based MEMS gas sensor.

[0071] Specifically, after the wafer-level fabrication of the MEMS sensor array chip is completed, a dicing machine is used to independently cut the MEMS sensor array chip from the wafer into individual chips. The complete wafer-level process can ensure the process consistency between different sensor array chips, thus ensuring the reusability of the algorithm.

[0072] Example 3

[0073] A silicon-based MEMS gas sensor array chip is provided, which adopts the silicon-based MEMS gas sensor array chip structure described in Example 1, and its fabrication method adopts the fabrication method of the silicon-based MEMS gas sensor array chip structure described in Example 2.

[0074] In this study, different gas-sensitive material thin films were prepared in four gas detection zones. The gas detection capability of metal oxide semiconductors is directly related to the operating temperature. At different operating temperatures, the same metal oxide semiconductor will exhibit different response trends, resulting in significantly different response waveforms. For example, SnO2 and the catalyst Pd were prepared in gas detection zone 1 for highly sensitive hydrogen detection; WO3 was prepared in gas detection zone 2 for highly sensitive ethanol detection; IGO material was prepared in gas detection zone 3 for highly sensitive formaldehyde detection; and Ce-doped NiO was prepared in gas detection zone 4 for highly sensitive NO2 detection.

[0075] The silicon-based MEMS gas sensor array chip prepared in this embodiment is used to conduct multiple sets of experiments to detect the four target gases at different concentrations. Four voltages, V1, V2, V3, and V4 (which can provide the optimal operating temperature for the metal oxide semiconductor on the gas detection area or other operating temperatures that can produce special gas-sensitive response trends), are applied to the four gas detection areas. Pattern recognition algorithms, such as PCA and LDA, are used to identify and classify the detection data, thereby realizing intelligent detection of the MEMS gas sensor array chip.

[0076] Furthermore, when detecting a gas, different voltages can be applied to different gas-sensitive detection zones to provide different operating temperatures, enabling rapid screening of the optimal operating temperature for gas-sensitive materials.

[0077] In another embodiment, different voltages are applied to different gas-sensitive detection zones to provide different operating temperatures, which can be used to distinguish multiple target gases by utilizing the different response trends of the same metal oxide semiconductor at different operating temperatures.

[0078] Based on the above embodiments, gas sensing detection is performed using any gas sensing material and at any operating temperature in four gas sensing detection zones. The gas sensing materials in different gas sensing detection zones can be the same or different, and the operating temperatures provided in different gas sensing detection zones can be the same or different.

[0079] When the silicon-based MEMS gas sensor provided in this embodiment of the invention detects gas, the serpentine heating electrode in the gas-sensitive detection area and the heating electrode pin pad are connected to form an independent circuit, which can be controlled by independent voltage input. Different operating temperatures can be provided for the metal oxide semiconductor gas-sensitive material on each gas detection membrane area. This allows for obtaining gas-sensitive detection data of the same gas-sensitive material at different temperatures, and also ensures that multiple gas-sensitive materials operate at their optimal operating temperatures simultaneously, thus enriching the data volume and providing diversified solutions for intelligent gas identification.

[0080] It should be noted that the connection method between the electrode and the pad provided in this embodiment is only a typical example and does not limit the present invention. Other connection methods with the same idea can be explained by the present invention.

[0081] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A silicon-based MEMS gas sensor, characterized in that, include: A silicon wafer substrate, a detection area disposed above an etching cavity on the silicon wafer substrate, and a control electrode area disposed around the etching cavity; The detection area includes four gas-sensitive detection areas arranged in a grid pattern; the control electrode area includes four independent heating electrode pins, four independent test electrode pins, two shared heating electrode pins, and two shared test electrode pins. The heating electrode layer of the gas-sensitive detection area includes one heating electrode, and the test electrode layer includes two test electrodes; one end of the heating electrode is connected to an independent heating electrode pin, and the other end is connected to the heating electrode of the gas-sensitive detection area adjacent in the vertical direction, and they are all connected to a common heating electrode pin. The gas-sensitive material film of the gas-sensitive detection area is laid flat on two test electrodes; wherein, the test electrode includes an independent test electrode and a common test sub-electrode, forming an interdigitated electrode; four common test sub-electrodes form a complete common test electrode; the independent test electrode is connected to the independent test electrode pin, and the two ends of the common test electrode are connected to the common test electrode pin. Each gas-sensitive detection zone is independently temperature-controlled via an independent heating electrode pin, and each gas-sensitive detection zone is independently gas-sensitive via an independent test electrode pin; the common test electrode is fishbone shaped and passes horizontally through the center of the four gas-sensitive detection zones, forming interdigitated electrodes with the independent test electrodes of the four gas-sensitive detection zones respectively. The heating electrode is strip-shaped and is uniformly and meanderingly arranged in the heating electrode layer of the gas-sensitive detection area; The etched cavity is located at the center of the silicon wafer substrate. The cantilever support layer of the gas-sensitive detection area includes cantilever beams. Cantilever beams are respectively set at the horizontal and vertical axes of symmetry of the gas-sensitive detection area. The four cantilever beams of the detection area together support the cavity above the silicon wafer substrate to form a suspended structure.

2. A silicon-based MEMS gas sensor array, characterized in that, The sensor array includes multiple silicon-based MEMS gas sensors as described in claim 1.

3. A method for fabricating a silicon-based MEMS gas sensor, used to fabricate the silicon-based MEMS gas sensor as described in claim 1, characterized in that, Includes the following steps: S1. Deposit insulating material at the wafer level on the surface of a silicon wafer substrate to form a cantilever support layer covering the silicon wafer substrate; S2. Deposit metal at the wafer level on the cantilever support layer to form a heating electrode in the detection area and a heating electrode pin in the control electrode area; the detection area includes four gas-sensitive detection areas arranged in a grid pattern; the control electrode area includes four independent heating electrode pins and two shared heating electrode pins; one end of the heating electrode of the gas-sensitive detection area is connected to the independent heating electrode pin, and the other end is connected to the heating electrode of the vertically adjacent gas-sensitive detection area, and they are all connected to a shared heating electrode pin; S3. Deposit insulating material at the wafer level on the surface of the heating electrode to form an insulating layer covering the cantilever support layer and the heating electrode; S4. Deposit metal at the wafer level on the insulating layer to form a test electrode in the detection area and a test electrode in the control electrode area; the control electrode area includes 4 independent test electrode pins and 2 shared test electrode pins; the test electrode includes one independent test electrode and one shared test sub-electrode, forming an interdigitated electrode; the four shared test sub-electrodes form a complete shared test electrode. The independent test electrode is connected to the independent test electrode pin, and the two ends of the common test electrode are connected to the common test electrode pin; S5. An etching window is formed above each independent heating electrode pin and the common heating electrode pin, the etching window penetrating the insulating layer and exposing the upper surface of the independent heating electrode pin and the common heating electrode pin; S6. A corrosion window is formed around the gas-sensitive detection area, and the corrosion window penetrates the insulating layer and the cantilever support layer. S7. A gas-sensitive material film is formed for each gas-sensitive detection area by deposition and sputtering; the gas-sensitive material film is laid flat on two test electrodes; S8. Perform a dicing process on the silicon-based MEMS gas sensor array fabricated at the wafer level to obtain a single silicon-based MEMS gas sensor. The common test electrode is fishbone shaped and passes horizontally through the center of the four gas-sensitive detection areas, forming interdigitated electrodes with the independent test electrodes of the four gas-sensitive detection areas respectively. The heating electrode is strip-shaped and is uniformly and meanderingly arranged in the heating electrode layer of the gas-sensitive detection area; The cantilever support layer of the gas-sensitive detection area includes cantilever beams. Cantilever beams are respectively set at the horizontal and vertical axes of symmetry of the gas-sensitive detection area. The four cantilever beams of the detection area together support the cavity above the silicon wafer substrate to form a suspended structure.

4. The method for fabricating a silicon-based MEMS gas sensor as described in claim 3, characterized in that, The cantilever support layer material is an ONO composite material; wherein, the thickness of the first silicon oxide layer ranges from 100-200nm, the thickness of the second silicon nitride layer ranges from 300nm-700nm, and the thickness of the third silicon oxide layer ranges from 500nm-1100nm.

5. The method for fabricating a silicon-based MEMS gas sensor as described in claim 4, characterized in that, The heating electrode is a uniformly meandering metal electrode; The insulating layer material is silicon oxide or silicon nitride or a mixture of the two; The test electrode consists of an independent test electrode and a shared test sub-electrode, forming an interdigitated electrode; four shared test sub-electrodes constitute a complete shared test electrode. The etching solution used in the etching window is tetramethylammonium hydroxide, which forms an etching cavity under the gas-sensitive material film, retaining only the gas-sensitive detection area and the cantilever beam supporting the electrode; the etching cavity is located at the center of the silicon wafer substrate; The gas-sensitive material film is a metal oxide semiconductor material with a thickness ranging from 100nm to 800nm.

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