Hydrogen sensor and preparation method thereof

Abstract

The invention provides a hydrogen sensor and a preparation method thereof.The hydrogen sensor comprises a substrate layer, a functional layer and at least one isolation groove, the substrate layer comprises a supporting area and a functional area, the functional area is provided with a cavity and a beam island structure, and the cavity is located below the beam island structure; the functional layer comprises a working area with a temperature control structure and a gas sensitive structure, and the beam island structure is used for supporting the working area; the at least one isolation groove is located on the peripheral side of the working area, the isolation groove penetrates through the functional layer and extends to the substrate layer to be communicated with the cavity, and the isolation groove and the cavity can isolate heat loss of the working area. According to the hydrogen sensor, by arranging the beam island structure, the cavity and the isolation groove, heat exchange between the working area and the external environment can be effectively isolated, the temperature around the working area can be adjusted through the temperature control structure, and the situation that the sensitivity of the hydrogen sensor is affected by environment temperature fluctuation is avoided; the thermal response speed of the hydrogen sensor is favorably improved.

Description

Technical Field

[0001] The present application relates to the technical field of hydrogen sensors, and in particular to a hydrogen sensor and a method for preparing the same. Background Art

[0002] In the construction of ultra-high voltage (UHV) transmission lines, oil-filled voltage and current transformer bushings are widely used at the junctions between transformers and transmission lines. During operation, the temperature of these bushings rises rapidly within 3-5 minutes due to the dynamic fluctuations of the grid load. This causes the insulating oil to decompose and produce characteristic gases, particularly hydrogen. Excessive hydrogen content in the insulating oil within the bushings accelerates oil aging, shortens the service life of the insulation material, and can even cause accidents. Therefore, measuring the hydrogen content in insulating oil is a crucial indicator for evaluating the performance of insulating oil in power grids and is crucial to grid safety.

[0003] At present, the measurement of hydrogen in the insulating oil of the power grid mainly adopts the method of extracting insulating oil samples and bringing them back for analysis to determine the quality of the insulating oil. The main drawbacks of this method are long detection cycle, discontinuous and delayed detection data, and loss and pollution of the insulating oil.

[0004] Hydrogen sensors can be used to address the problem of inability to continuously detect gases. However, these sensors have very strict requirements for the operating temperature of the ambient environment. They must heat up and maintain the set operating temperature during operation. In scenarios like the aforementioned rapid temperature increase within 3 to 5 minutes, the hydrogen sensor's response to the rapidly changing ambient temperature is delayed. This results in the hydrogen concentration detected by the hydrogen sensor not corresponding to the ambient temperature at the time, but instead being based on the hydrogen concentration monitored at the previous moment, resulting in inaccurate hydrogen concentration detection by the hydrogen sensor. Therefore, a hydrogen sensor with fast thermal response and high sensitivity is needed. Summary of the Invention

[0005] To address the above-mentioned problems in the prior art, this application provides a hydrogen sensor and a method for manufacturing the same. The specific technical solution is as follows: In one aspect, the present application provides a hydrogen sensor, comprising: A substrate layer includes a support area and a functional area, wherein the functional area is provided with a cavity and a beam-island structure, and the cavity is located below the beam-island structure; The functional layer includes a working area having a temperature control structure and an air-sensing structure, and the beam island structure is used to support the working area; At least one isolation trench is located on a peripheral side of the working area, and the isolation trench penetrates the functional layer and extends to the substrate layer to communicate with the cavity.

[0006] In a possible implementation manner, the working area is located directly above the beam island structure.

[0007] In a possible implementation manner, the orthographic projection of the beam island structure on the functional layer can cover the working area.

[0008] In a possible implementation manner, the beam-island structure includes a connected island structure and at least two beam structures, the beam structure is connected to the support area, the beam structures are spaced apart in the circumferential direction of the island structure, and the island structure is suspended above the cavity.

[0009] In a possible implementation manner, the isolation grooves are located on the peripheral side of the island structure, and the beam structure is located between adjacent isolation grooves.

[0010] In a possible implementation manner, the beam island structure satisfies at least one of the following characteristics: The width of the beam structure is 50-200 μm; The radial size of the island structure is 500-2000 μm; The thickness of the island structure is 1-50 μm In a possible implementation manner, the width of the isolation trench is 10-500 μm.

[0011] In a possible implementation manner, the substrate layer further includes a shielding layer located at the periphery of the beam-island structure, and the shielding layer is used to form a depletion layer between the beam-island structure and the supporting region.

[0012] In a possible implementation manner, the shielding layer includes at least one shielding structure, the shielding structure is located in a connection area between the beam structure and the support area, and the shielding structure isolates the beam structure from the support area.

[0013] In a possible implementation, the beam structure includes a connected supporting segment and a connecting segment, the connecting segment is connected to the island structure at one end facing away from the supporting segment, the supporting segment is embedded in the supporting area, and the shielding structure is arranged around the supporting segment.

[0014] In a possible implementation manner, an insulating layer is further included, wherein the insulating layer is located between the functional layer and the substrate layer, and the isolation trench passes through the insulating layer.

[0015] In a possible implementation manner, the insulating layer satisfies at least one of the following characteristics: The thickness of the insulating layer is 50-500 nm; The insulating layer is made of at least one of silicon dioxide, silicon nitride and a silicon dioxide / silicon nitride composite material.

[0016] In a possible implementation manner, the gas-sensing structure includes a capacitor component and a resistor, and the resistor is located in the middle of the capacitor component.

[0017] In a possible implementation manner, the capacitor assembly includes a hydrogen-sensitive capacitor and a reference capacitor, and the hydrogen-sensitive capacitor and the reference capacitor are symmetrically arranged relative to the resistor.

[0018] In a possible implementation manner, the temperature control structure includes a heating coil and a temperature measuring coil, the heating coil is arranged on the outside of the capacitor assembly, and the temperature measuring coil is located in the middle of the heating coil.

[0019] In a possible implementation manner, a passivation layer is further formed above the functional layer, the passivation layer covers the working area, and a window structure capable of at least partially exposing the gas-sensitive structure is provided on the passivation layer.

[0020] On the other hand, the present application also provides a method for preparing a hydrogen sensor, the preparation method comprising: Providing a substrate layer, the substrate layer comprising a support area and a functional area; forming a functional layer on one side of the substrate layer, wherein the functional layer includes a working area having a gas-sensing structure and a temperature-controlling structure; Based on the etching process, a cavity, a beam-island structure and at least one isolation groove on the peripheral side of the working area are formed in the functional area. The beam-island structure is located above the cavity and is used to support the working area. The isolation groove penetrates the functional layer and extends to the substrate layer to communicate with the cavity.

[0021] In a possible implementation manner, forming the cavity, the beam island structure, and the at least one isolation trench located on the periphery of the working area in the functional area based on an etching process includes: forming the cavity and the substrate thin layer in the functional area based on an etching process, wherein the substrate thin layer is located between the cavity and the working area; The functional layer and the substrate thin layer are etched based on an etching process to form at least one isolation groove and the beam island structure penetrating the functional layer and the substrate thin layer, wherein the isolation groove penetrates the substrate thin layer and communicates with the cavity.

[0022] In a possible implementation manner, the process of forming the beam-island structure includes: Forming the beam-island structure having a connected island structure and at least two beam structures based on an etching process; The beam island structure and the isolation groove are formed integrally. The beam structure is located between adjacent isolation grooves. The isolation grooves are located on the periphery of the island structure. The island structure is suspended above the cavity.

[0023] In a possible implementation manner, before forming the functional layer, the preparation method includes: The substrate layer is locally ion-implanted based on a patterning process to form a shielding layer located at the periphery of the beam-island structure. The shielding layer can form a depletion layer between the beam-island structure and the supporting area.

[0024] In a possible implementation manner, before forming the functional layer, the preparation method further includes: An insulating layer is formed on one side of the substrate layer, and the isolation trench can penetrate the insulating layer.

[0025] In a possible implementation manner, the preparation method further comprises: forming a passivation layer on the functional layer, wherein the passivation layer covers the working area; A window structure is formed on the passivation layer, wherein the window structure can at least partially expose the gas-sensing structure.

[0026] Based on the above technical solution, this application has the following beneficial effects: The present application provides a hydrogen sensor comprising a substrate layer, a functional layer, and at least one isolation groove. The substrate layer comprises a support area and a functional area, wherein the functional area is provided with a cavity and a beam island structure, with the cavity being located below the beam island structure. The functional layer comprises a working area having a temperature control structure and a gas-sensing structure, with the beam island structure being used to support the working area. At least one isolation groove is located around the working area, the isolation groove penetrates the functional layer, extends to the substrate layer, and connects to the cavity. The isolation groove and the cavity can isolate heat loss from the working area. Thus, the beam island structure, the cavity, and the isolation groove can effectively isolate heat exchange between the working area and the external environment, and the temperature control structure can regulate the temperature around the working area, thereby maintaining the temperature around the hydrogen sensor at a preset operating temperature, preventing ambient temperature fluctuations from affecting the sensitivity of the hydrogen sensor and facilitating improved thermal response speed of the hydrogen sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] Figure 1 : A top view of a hydrogen sensor provided in an embodiment of the present application; Figure 2 : A side view of a hydrogen sensor provided in an embodiment of the present application; Figure 3 : A top view of a substrate layer of a hydrogen sensor provided in an embodiment of the present application; Figure numerals: 1-substrate layer, 11-cavity, 12-beam-island structure, 121-island structure, 122-beam structure, 13-shielding layer, 2-functional layer, 21-resistance, 22-hydrogen-sensitive capacitor, 23-reference capacitor, 24-heating coil, 25-temperature measuring coil, 3-isolation groove, 4-insulating layer, 5-flexible circuit board. DETAILED DESCRIPTION

[0029] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] It should be noted that in the description of this application, for the following defined terms, these definitions should be applied unless a different definition is given in the claims or elsewhere in this specification. All numerical values, whether or not explicitly indicated, are defined herein as being modified by the term "about". The term "about" generally refers to a numerical range that a person of ordinary skill in the art would consider to be equivalent to the stated value to produce substantially the same properties, functions, results, etc. A numerical range indicated by a low value and a high value is defined to include all numerical values ​​included in the numerical range and all subranges included in the numerical range.

[0031] It should be noted that, in the description of this application, the terms "first," "second," etc. are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions.

[0032] It should be noted that, in the description of this application, the meaning of the terms "on...", "above...", "above...", and "above..." should be interpreted in the broadest sense, meaning that the description containing these terms is interpreted as "the component can be set on another component in a direct contact manner, or there can be an intermediate component or layer between the components". In addition, for the convenience of description, this application may also use spatially relative terms such as "under...", "under...", "under...", "on...", "above...", "above...", "lower", "upper", etc. to describe the relationship between one element or component and another element or component shown in the drawings. In addition to the orientations described in the figures, the spatially relative terms are also intended to cover different orientations of the device in use or operation. The device can be oriented in other ways (rotated 90° or in other orientations), and the spatially relative descriptors used in this application can be interpreted accordingly.

[0033] As used herein, the term "layer" refers to a portion of a material comprising an area having a certain thickness. A layer may extend over the entire underlying or superstructure, or may extend over a localized area of ​​the underlying or superstructure. Furthermore, a layer may be a region of a homogeneous or heterogeneous continuous structure whose thickness is less than the thickness of the continuous structure. For example, a layer may be located between the top and bottom surfaces of a continuous structure or between any pair of horizontal planes therebetween. A layer may extend horizontally, vertically, and / or along a tapered surface. A layer may comprise multiple layers.

[0034] It should be understood that the "surface" used in this application, such as "first surface", "second surface", etc., refers to the XY plane of the substrate layer 1, etc., and the "thickness direction" refers to the Z direction perpendicular to the XY plane. The "thickness" or "height" involved in this application refers to the Z-direction thickness or Z-direction height.

[0035] Hydrogen sensors require small temperature fluctuations in their operating environment. When the operating temperature of a hydrogen sensor fluctuates greatly, most existing hydrogen sensors have a thermal response hysteresis problem, causing their detection results to deviate from the actual value and failing to accurately and timely sense whether the hydrogen concentration in the measured environment has reached a dangerous threshold. Based on the consideration of improving the detection accuracy and sensitivity of hydrogen sensors, the embodiments of the present application provide a hydrogen sensor that can greatly improve the thermal response speed, has excellent thermal insulation effect, and ensures sufficiently accurate detection accuracy.

[0036] The following references Figure 1 and Figure 2The present invention provides a hydrogen sensor comprising a substrate layer 1, a functional layer 2, and at least one isolation slot 3. The substrate layer 1 comprises a support region and a functional region, wherein the functional region is provided with a cavity 11 and a beam island structure 12, with the cavity 11 located below the beam island structure 12. The functional layer 2 comprises a working region having a temperature control structure and a gas-sensing structure, wherein the beam island structure 12 is used to support the working region and isolate heat loss from the functional region. At least one isolation slot 3 is located around the working region, and the isolation slot 3 penetrates the functional layer 2 and extends to the substrate layer 1, where it connects to the cavity 11. The isolation slot 3 and the cavity 11 can be used to isolate heat loss. Thus, the beam island structure 12, the cavity 11, and the isolation slot 3 can effectively isolate heat exchange between the working region and the external environment, and the temperature control structure can regulate the temperature around the working region, thereby maintaining the temperature around the hydrogen sensor at a preset operating temperature and preventing ambient temperature fluctuations from affecting the response speed and sensitivity of the hydrogen sensor.

[0037] Specifically, substrate layer 1 may be a semiconductor or a silicon-on-insulator (SOI) substrate. An SOI substrate is a semiconductor material layer formed on an insulator layer. The insulator layer may be, for example, a buried oxide layer or a silicon oxide layer, and the insulator layer is disposed on a silicon substrate or a glass substrate. In a specific implementation, the semiconductor material of substrate layer 1 may include one or more of silicon, germanium, a compound semiconductor, and an alloy semiconductor. Compound semiconductors may include one or more of silicon carbide, gallium arsenide, gallium phosphide, indium phosphide, indium arsenide, and indium antimonide. Alloy semiconductors may include one or more of silicon germanium, gallium arsenic phosphide, aluminum indium arsenide, aluminum gallium arsenide, gallium arsenide, gallium indium phosphide, and gallium indium arsenic phosphide.

[0038] Specifically, the working area is located directly above the beam-island structure 12 , which can provide support for the working area and isolate heat loss from the working area.

[0039] Specifically, the orthographic projection of the beam-island structure 12 on the functional layer 2 can cover the working area. It can be understood that the total area of ​​the opening position of the beam-island structure 12 is larger than the area of ​​the working area to ensure that the beam-island structure 12 can isolate heat transfer, thereby reducing temperature fluctuations in the working area and effectively avoiding the influence of ambient temperature changes on the sensing accuracy of the hydrogen sensor.

[0040] Specifically, the edges of the working area do not exceed the edges of the isolation groove 3, so that the isolation groove 3 and the cavity 11 can isolate heat loss and prevent the occurrence of a situation where trace heat is quickly dissipated and cannot be detected.

[0041] In some embodiments, the beam-island structure 12 includes a connected island structure 121 and at least two beam structures 122. The beam structures 122 are connected to the support area and are spaced apart circumferentially around the island structure 121. The island structure 121 is suspended above the cavity 11. In this way, the beam structures 122 can provide support for the island structure 121, thereby supporting the working area. Furthermore, by providing at least two beam structures 122 circumferentially around the island structure 121, the core of the hydrogen sensor can be effectively prevented from deflecting, thereby improving the stability and reliability of the hydrogen sensor.

[0042] Specifically, the island structure 121 has a smaller thickness than the supporting area, and the working area located directly above the island structure 121 can have a larger deformation when absorbing hydrogen, which is beneficial to expanding the sensing range of hydrogen concentration and improving the sensitivity of the hydrogen sensor.

[0043] refer to Figure 3 , Figure 3 A top view of a substrate layer 1 of a hydrogen sensor provided in an embodiment of the present application is shown. Preferably, the beam-island structure 12 includes four beam structures 122 spaced apart circumferentially around the island structure 121, with a first predetermined distance between adjacent beam structures 122. This allows the four beam structures 122 to support the island structure 121 in different directions, thereby improving the stability of the beam-island structure 12.

[0044] Specifically, the outline shape of the island structure 121 may include but is not limited to a circle, a square, or other shapes that can meet application requirements. In one embodiment, the outline shape of the island structure 121 is a circle.

[0045] Specifically, the width of the beam structure 122 is 50-200μm; it can be understood that the width of the beam structure 122 can be any point value in the range of 50-200μm; for example, the width of the beam structure 122 can be 50μm, 90μm, 100μm, 150μm, 200μm, etc. If the width of the beam structure 122 is less than 50μm, it cannot provide sufficient mechanical support for the island structure 121; if the width of the beam structure 122 is greater than 200μm, it may cause heat to be transferred through the beam structure 122, which is not conducive to improving the thermal insulation effect. In this way, controlling the width of the beam structure 122 within the above range can provide good support while allowing the beam island structure 12 to effectively isolate the working area from the outside world. In one example, the width of the beam structure 122 can be understood as: the distance between adjacent isolation grooves 3 in the circumferential direction of the island structure 121. Preferably, the width of the beam structure 122 is 100-150μm.

[0046] Specifically, the radial dimension of the island structure 121 is 500-2000 μm. It is understood that the radial dimension of the island structure 121 can be any value within the range; for example, the radial dimension of the island structure 121 can be 500 μm, 700 μm, 1000 μm, 1500 μm, 2000 μm, etc. By controlling the radial dimension of the island structure 121 within the above range, stable mechanical support can be provided for the working area, and the area of ​​the working area can be expanded within an appropriate range, facilitating the integration of more working components and improving the performance of the hydrogen sensor. Specifically, the size of the island structure 121 can be adjusted as needed.

[0047] Specifically, the thickness of island structure 121 is 1-50 μm. It is understood that the thickness of island structure 121 can be any value within this range. For example, the thickness of island structure 121 can be 1 μm, 10 μm, 15 μm, 30 μm, 50 μm, etc. Controlling the thickness of island structure 121 within this range provides good mechanical support for the work area, improves thermal insulation, and avoids excessive thickness that would increase the thermal conductivity of island structure 121. Preferably, the thickness of island structure 121 is 15-30 μm.

[0048] In some embodiments, the isolation groove 3 is located on the peripheral side of the island structure 121. The isolation groove 3 can effectively isolate the heat transfer between the island structure 121 and the support area, and isolate external signal interference, thereby improving the measurement accuracy of the hydrogen sensor for trace hydrogen; the beam structure 122 is located between adjacent isolation grooves 3, connecting the island structure 121 and the support area, and providing mechanical support for the island structure 121.

[0049] Specifically, the width of the isolation trench 3 is 10-500μm, where the width of the isolation trench 3 can be understood as the distance between its sidewall close to the island structure 121 and its sidewall away from the island structure 121. It is understood that the width of the isolation trench 3 can be any value between 10-500μm; illustratively, the width of the isolation trench 3 can be 10μm, 50μm, 100μm, 200μm, 350μm, 500μm, etc. Thus, controlling the width of the isolation trench 3 within the above range can effectively reduce external interference signals and effectively block heat loss, which is conducive to improving the sensing accuracy of the hydrogen sensor for trace hydrogen sensing signals. Preferably, the width of the isolation trench 3 is 200-300μm.

[0050] In some embodiments, the substrate layer 1 also includes a shielding layer 13 located outside the beam-island structure 12. The shielding layer 13 is used to form a depletion layer between the beam-island structure 12 and the supporting area to prevent interference from external carriers and free electrons of the beam-island structure 12, which is beneficial to reducing the impact of free electrons on the working area.

[0051] Specifically, shielding layer 13 includes at least one shielding structure located at the connection between beam structure 122 and the support region. The shielding structure isolates beam structure 122 from the support region. This shielding structure isolates electron interference between beam structure 122 and the support region, thereby preventing free electrons in the support region from affecting beam island structure 12 and the working area.

[0052] In some embodiments, the beam structure 122 includes a connected support segment and a connecting segment. The connecting segment's end, facing away from the support segment, is connected to the island structure 121. The support segment is embedded in the support area, and the shielding structure is disposed around the support segment. In this manner, the number of shielding structures is the same as the number of beam structures 122, with each shielding structure disposed around a corresponding support segment of the beam structure 122. This ensures the support strength of the beam structure 122 while isolating external interference electrons.

[0053] Specifically, the shielding layer 13 and the isolation groove 3 are arranged around the circumference of the beam-island structure 12 to isolate the carriers and free electrons between the beam-island structure 12 and the supporting area.

[0054] In some embodiments, the hydrogen sensor further includes an insulating layer 4, which is located between the functional layer 2 and the substrate layer 1. The isolation trench 3 extends through the insulating layer 4. The insulating layer 4 isolates the functional layer 2 from the substrate layer 1, preventing electrical signals between the functional layer 2 and the substrate layer 1 from interfering with each other, thereby improving the hydrogen absorption rate of the gas-sensing structure.

[0055] Specifically, the material of the insulating layer 4 includes at least one of silicon dioxide, silicon nitride and a silicon dioxide / silicon nitride composite material.

[0056] The thickness of the insulating layer 4 is 50-500nm; it is understandable that the thickness of the insulating layer 4 can be any value between 50-500nm; illustratively, the thickness of the insulating layer 4 can be 50nm, 100nm, 200nm, 300nm, 400nm, 500nm, etc. In this way, by controlling the thickness of the insulating layer 4 within the above range, the insulating layer 4 can play a good role in thermal insulation, while taking lightweight into account to the greatest extent, and effectively blocking the signal crosstalk between the functional area and the substrate layer 1, and is conducive to improving the absorption rate of hydrogen by the capacitor and resistor. Preferably, the thickness of the insulating layer 4 is 200-250nm, which can effectively prevent signal interference while having good economic benefits.

[0057] In some embodiments, the gas-sensing structure includes a capacitor assembly and a resistor 21, with the resistor 21 located in the middle of the capacitor assembly. The capacitor assembly and resistor 21 can be used to sense hydrogen gas and form a signal conditioning circuit to amplify and condition the weak signal output by the hydrogen sensor to ensure the accuracy of the output signal.

[0058] In some embodiments, the capacitor assembly includes a hydrogen-sensitive capacitor 22 and a reference capacitor 23, and the hydrogen-sensitive capacitor 22 and the reference capacitor 23 are symmetrically arranged relative to the resistor 21. Exemplarily, the resistor 21 is located on the central axis of the working area, and the hydrogen-sensitive capacitor 22 and the reference capacitor 23 are symmetrically arranged relative to the resistor 21, so that the hydrogen-sensitive capacitor 22 and the reference capacitor 23 form a contrast, which is conducive to reducing the impact of external interference factors on the detection results of the hydrogen sensor.

[0059] In some embodiments, there is a single variable between the hydrogen-sensitive capacitor 22 and the reference capacitor 23; specifically, the single variable between the hydrogen-sensitive capacitor 22 and the reference capacitor 23 is: the hydrogen-sensitive capacitor 22 can adsorb hydrogen, while the reference capacitor 23 is completely isolated from hydrogen. In this way, the hydrogen-sensitive capacitor 22 and the reference capacitor 23 are symmetrically arranged, so that there are no other interference factors when the hydrogen-sensitive capacitor 22 and the reference capacitor 23 are working, which is conducive to improving the accuracy of the detection results.

[0060] Specifically, the hydrogen-sensitive capacitor 22 may include a first palladium alloy film, which is used to deform its structure after absorbing hydrogen. The material of the first palladium alloy film includes at least one of palladium nickel gold, palladium silver gold, palladium titanium gold and palladium chromium gold, which can react with hydrogen in the environment, so that the structure of the first palladium alloy film is deformed after absorbing hydrogen, thereby enabling the detection of hydrogen.

[0061] Specifically, the palladium content in the first palladium alloy film is 50-80%, the nickel, silver, titanium or chromium content is 2-25%, and the gold content is 0-25%; it can be understood that the palladium content in the first palladium alloy film is any point value between 50-80%, the nickel, silver, titanium or chromium content is any point value between 2-25%, and the gold content is any point value between 0-25%.

[0062] Preferably, the hydrogen-sensitive capacitor 22 is a metal-oxide-semiconductor structure. In this structure, hydrogen is adsorbed onto the surface of the first palladium alloy film and decomposed into two hydrogen atoms. The hydrogen atoms diffuse through the first palladium alloy film to the interface in contact with the oxide, where a bonding reaction occurs. This bonding process causes the capacitance-voltage characteristic curve of the hydrogen-sensitive capacitor 22 to change, resulting in a voltage offset. The voltage offset is related to the hydrogen concentration, and the hydrogen concentration can be measured based on this characteristic of the hydrogen-sensitive capacitor 22.

[0063] In some embodiments, the resistor 21 is powered by a constant current source, which can greatly improve the detection accuracy of the hydrogen sensor. When the resistor 21 adsorbs hydrogen, its resistance value will increase. When powered by a constant current source, the current remains unchanged. Therefore, the heat generated by the resistor 21 is proportional to the resistance value. When the resistance value of the resistor 21 increases, a small amount of thermal effect will be generated, causing the temperature around the working area to increase, thereby increasing the resistance value of the resistor 21 and improving the sensitivity of the hydrogen sensor.

[0064] In some embodiments, resistor 21 includes a hydrogen-sensing resistor, which can be a continuously bent S-shaped resistor. This ensures that more hydrogen-sensing resistors can be exposed to hydrogen within the limited space of the window structure, thereby ensuring that even trace amounts of hydrogen can be detected, improving the detection sensitivity of hydrogen, and also increasing the maximum detection range of hydrogen, thereby bidirectionally expanding the detection range of hydrogen by the hydrogen sensor of the present invention; this is conducive to improving space utilization and reducing the overall volume of the hydrogen sensor. It can be understood that the shape of the hydrogen-sensing resistor can be set according to actual application requirements.

[0065] In some embodiments, the temperature control structure includes a heating coil 24 and a temperature measuring coil 25. The heating coil 24 is disposed outside the capacitor assembly, and the temperature measuring coil 25 is located in the middle of the heating coil 24. The heating coil 24 is used to heat the temperature around the gas-sensing structure, and the temperature measuring coil 25 is used to detect the temperature in the middle of the working area. The heating coil 24 and the temperature measuring coil 25 together constitute a closed-loop temperature control system, maintaining the dynamic stability of the temperature around the working area, thereby stabilizing the operating temperature of the hydrogen sensor.

[0066] Specifically, there is a preset interval between the heating coil 24 and the gas-sensing structure therein to avoid cross-interference between the heating coil 24 and the gas-sensing structure during operation.

[0067] Specifically, the material of the heating coil 24 includes at least one of nickel, nickel-chromium alloy, platinum, platinum-rhodium alloy and doped silicon, which has high resistivity, high temperature resistance and corrosion resistance, which is conducive to improving heating efficiency, achieving rapid thermal response and precise temperature control, and thus improving the working performance of the hydrogen sensor.

[0068] Specifically, the temperature measuring coil 25 can be a continuously bent S-shape, which is beneficial to increase the contact area between the temperature measuring coil 25 and the surrounding environment, thereby improving the sensitivity and response speed of temperature measurement; and the design of the S-shaped coil can increase the mechanical strength of the coil, making it durable.

[0069] Specifically, the material of the temperature measuring coil 25 includes at least one of nickel, platinum and doped silicon, which has high heat conduction efficiency, making it easier for heat to be conducted into the temperature measuring coil 25, thereby improving the accuracy of temperature measurement.

[0070] In some embodiments, the hydrogen sensor includes a flexible circuit board 5, located on the functional layer 2, to provide mechanical support and electrical connections for the hydrogen sensor's operating area. The flexible circuit board 5 can adapt to volume changes in the gas-sensing structure, effectively suppressing stress accumulation and improving the stability and service life of the hydrogen sensor. Specifically, the flexible circuit board 5 includes a hollow structure located directly above the beam island structure 12, which reduces the static pressure difference between the functional area and the supporting area, thereby improving the reliability of the hydrogen sensor.

[0071] In some embodiments, the flexible circuit board 5 includes a solder pad and a lead. The solder pad is located directly above the support area. The solder pad is electrically connected to the gas-sensing structure and the temperature-control structure through the lead. The solder pad and the lead can be used to fix the gas-sensing structure and the temperature-control structure, and can also be used to connect the hydrogen sensor to an external circuit. In one example, the external control circuit is connected to the gas-sensing structure and the temperature-control structure through the solder pad and the lead to provide a constant current source or a constant voltage source. In another example, the electrical signal generated by the hydrogen sensor is transmitted to an external device through the solder pad and the lead for processing and analysis.

[0072] In some embodiments, the hydrogen sensor also includes a passivation layer formed above the functional layer 2, and the passivation layer covers the working area. The passivation layer is used to protect the working area of ​​the hydrogen sensor, prevent components in the working area from being oxidized or contaminated, and is beneficial to improving the durability of the hydrogen sensor; a window structure is provided on the passivation layer, which can at least partially expose the gas-sensitive structure, so that the gas-sensitive structure can contact and sense hydrogen through the window structure.

[0073] Specifically, the window structure can expose the hydrogen-sensitive capacitor 22 and the hydrogen-detecting resistor, so that the hydrogen-sensitive capacitor 22 and the hydrogen-detecting resistor can be in contact with hydrogen gas for detecting the concentration of hydrogen gas.

[0074] The following describes the preparation method of the hydrogen sensor provided in the embodiment of the present application. This specification provides the method operation steps as shown in the embodiment, but based on routine or non-creative work, more or fewer operation steps may be included. The order of steps listed in the embodiment is only one way of executing the steps among many steps and does not represent the only execution order. When the preparation method is actually executed, it can be executed in the order shown in the embodiment or the accompanying drawings or in parallel. The preparation method of the hydrogen sensor may include S1-S3: S1: Provide a substrate layer 1, which includes a support area and a functional area.

[0075] In some embodiments, the substrate layer 1 is locally ion implanted based on a patterning process to form a shielding layer 13 located outside the beam-island structure 12. The shielding layer 13 can form a depletion layer between the beam-island structure 12 and the supporting area, which is used to prevent interference from external carriers and free electrons of the beam-island structure 12, thereby reducing the impact of free electrons on the working area.

[0076] Specifically, performing a local ion implantation process on the substrate layer 1 based on a patterning process to form the shielding layer 13 located around the beam-island structure 12 includes: forming one or more mask layers on the substrate layer 1, wherein the mask layers can be formed on the substrate layer 1 by any suitable process such as deposition; forming a patterned mask layer using, for example, an etching process; performing a local ion implantation process on the substrate layer 1 based on the patterned mask layer; and removing the patterned mask layer to form the shielding layer 13 located around the beam-island structure 12. Exemplarily, the mask layer can be made of any suitable mask material, including, but not limited to, silicon oxide, silicon nitride, silicon carbonitride, and the like.

[0077] Specifically, the material for forming the shielding layer 13 by ion implantation includes at least one of nickel, nickel-chromium alloy, platinum, platinum-rhodium alloy and doped silicon. In this way, implanting high-energy ions into the semiconductor material can change the electrical properties of the material to form the shielding layer 13.

[0078] In some embodiments, an insulating layer 4 can be formed on at least one side of the substrate layer 1 by a thermal oxidation process, and the isolation groove 3 can penetrate the insulating layer 4. In this way, the insulating layer 4 can isolate the functional layer 2 from the substrate layer 1, avoiding mutual influence of electrical signals between the functional layer 2 and the substrate layer 1, which is beneficial to improving the absorption rate of hydrogen by the gas-sensitive structure. For example, a thermal oxidation process is performed on the surface of the SOI substrate to obtain a silicon dioxide insulating layer 4. The silicon dioxide prepared by the thermal oxidation process has high chemical stability and process repeatability, and its physical and chemical properties are less affected by fluctuations in process conditions.

[0079] In some embodiments, an insulating layer 4 can be formed on at least one side of the substrate layer 1 through a deposition process. For example, an insulating material is deposited on the surface of one side of the substrate layer 1 through a physical vapor deposition process, a chemical vapor deposition process, etc., wherein the insulating material may include but is not limited to silicon dioxide, silicon nitride, and a silicon dioxide / silicon nitride composite material, etc.

[0080] S2: forming a functional layer 2 on one side of the substrate layer 1, wherein the functional layer 2 includes a working area having a gas-sensing structure and a temperature-controlling structure.

[0081] Specifically, forming the functional layer 2 on one side of the substrate layer 1 includes: forming at least one metal thin film on one side of the substrate layer 1 through at least one deposition process; and patterning the metal thin film to form the functional layer 2. The deposition process may include, but is not limited to, electron beam evaporation, magnetron sputtering, and atomic layer deposition, as well as other methods for depositing metal thin films, which are not listed here.

[0082] Specifically, the material of the metal film is a palladium alloy, including at least one of palladium nickel gold, palladium silver gold, palladium titanium gold and palladium chromium gold. The palladium alloy material itself has a high adsorption capacity for hydrogen, which is beneficial to improving the sensitivity of the hydrogen sensor.

[0083] Specifically, a working area can be formed on the functional layer 2 at least through a patterned etching process, and the working area includes at least a gas-sensing structure and a temperature-control structure. Specifically, a hydrogen-sensitive capacitor 22, a reference capacitor 23, a resistor 21, a heating coil 24, and a temperature-measuring coil 25 can be formed at a predetermined position in the working area at least through a patterned etching process, for sensing hydrogen and maintaining the temperature of the working area at a predetermined working temperature.

[0084] S3: Based on the etching process, a cavity 11, a beam island structure 12, and at least one isolation groove 3 located on the peripheral side of the working area are formed in the functional area. The beam island structure 12 is located above the cavity 11 and is used to support the working area. The isolation groove 3 passes through the functional layer 2 and extends to the substrate layer 1 to be connected to the cavity 11.

[0085] In some embodiments, a cavity 11 and a thin substrate layer are formed in the functional area based on an etching process, and the thin substrate layer is located between the cavity 11 and the working area. The functional layer 2 and the thin substrate layer are etched based on the etching process to form at least one isolation trench 3 and a beam island structure 12 that penetrate the functional layer 2 and the thin substrate layer. The isolation trench 3 penetrates the thin substrate layer and is connected to the cavity 11. Preferably, a reactive ion etching process is used to form the cavity 11, the beam island structure 12, and the at least one isolation trench 3 on the substrate. In this way, the formation of the cavity 11, the beam island structure 12, and the isolation trench 3 can be achieved through the etching process, and the cavity 11 and the thin substrate layer are formed preferentially, which is conducive to positioning the beam island structure 12 and the isolation trench 3, reducing process complexity and cost.

[0086] In other embodiments, the functional layer 2 is etched based on an etching process to form at least one isolation groove 3 that penetrates the functional layer 2 and extends to the substrate layer 1; a cavity 11 and a beam island structure 12 are formed in the functional area based on the etching process, and the cavity 11 is connected to the isolation groove 3.

[0087] In some embodiments, the process of forming the beam-island structure 12 includes: forming the beam-island structure 12 having a connected island structure 121 and at least two beam structures 122 using an etching process; integrally forming the beam-island structure 12 and the isolation trenches 3, with the beam structures 122 located between adjacent isolation trenches 3, the isolation trenches 3 being located around the island structure 121, and the island structure 121 being suspended above the cavity 11. In this way, the beam structures 122 can provide support for the island structure 121, and the island structure 121, the cavity 11, and the isolation trenches 3 can be used to isolate heat transfer.

[0088] In some embodiments, a passivation layer is formed on the functional layer 2 , and the passivation layer covers the working area; a window structure is formed on the passivation layer, and the window structure can at least partially expose the gas-sensitive structure.

[0089] Specifically, the passivation layer can be formed on the surface of the functional layer 2 by any suitable process, such as deposition, to protect the surface of the functional layer 2 from damage during subsequent processes. Exemplarily, the passivation layer can include, but is not limited to, one or more of silicon oxide, silicon nitride, and silicon carbide.

[0090] Specifically, a window structure can be formed on the passivation layer at least by an etching process; preferably, the window structure can at least partially expose the gas-sensitive structure, so that the gas-sensitive structure can sense hydrogen and can be connected to external equipment through leads.

[0091] Based on the above preparation method, a hydrogen sensor having a substrate layer 1, a functional layer 2 and at least one isolation groove 3 can be prepared, wherein a cavity 11, a beam-island structure 12 and at least one isolation groove 3 located on the peripheral side of the working area are formed in the substrate layer 1 based on an etching process, the beam-island structure 12 is located above the cavity 11, and the cavity 11 is connected to the isolation groove 3. In this way, the beam-island structure 12, the cavity 11 and the isolation groove 3 can effectively isolate the heat exchange between the working area and the external environment, and the temperature around the working area can be adjusted through the temperature control structure in the working area, thereby maintaining the temperature around the hydrogen sensor at a preset working temperature, avoiding the influence of ambient temperature fluctuations on the sensitivity of the hydrogen sensor, and helping to improve the thermal response speed of the hydrogen sensor.

[0092] The above description has fully disclosed the specific embodiments of this application. It should be noted that any changes made by those skilled in the art to the specific embodiments of this application do not depart from the scope of the claims of this application. Accordingly, the scope of the claims of this application is not limited to the above specific embodiments.

Claims

1. A hydrogen sensor, characterized in that: include: A substrate layer includes a support area and a functional area, wherein the functional area is provided with a cavity and a beam-island structure, and the cavity is located below the beam-island structure; The functional layer includes a working area having a temperature control structure and an air-sensing structure, and the beam island structure is used to support the working area; At least one isolation trench is located on a peripheral side of the working area, and the isolation trench penetrates the functional layer and extends to the substrate layer to communicate with the cavity.

2. The hydrogen sensor according to claim 1, characterized in that The working area is located directly above the beam island structure.

3. The hydrogen sensor according to claim 1, characterized in that The orthographic projection of the beam island structure on the functional layer can cover the working area.

4. The hydrogen sensor according to claim 1, characterized in that The beam-island structure includes a connected island structure and at least two beam structures, the beam structure is connected to the support area, the beam structures are spaced apart in the circumferential direction of the island structure, and the island structure is suspended above the cavity.

5. The hydrogen sensor according to claim 4, characterized in that The isolation grooves are located on the peripheral side of the island structure, and the beam structure is located between adjacent isolation grooves.

6. The hydrogen sensor according to claim 4, characterized in that The beam island structure satisfies at least one of the following characteristics: The width of the beam structure is 50-200 μm; The radial size of the island structure is 500-2000 μm; The thickness of the island structure is 1-50 μm.

7. The hydrogen sensor according to any one of claims 1 to 6, characterized in that: The width of the isolation groove is 10-500 μm.

8. The hydrogen sensor according to any one of claims 1 to 6, characterized in that: The substrate layer further includes a shielding layer located at the periphery of the beam-island structure, and the shielding layer is used to form a depletion layer between the beam-island structure and the supporting region.

9. The hydrogen sensor according to claim 8, characterized in that The shielding layer includes at least one shielding structure, which is located in a connection area between the beam structure and the support area. The shielding structure isolates the beam structure from the support area.

10. The hydrogen sensor according to claim 9, characterized in that The beam structure includes a connected supporting section and a connecting section. One end of the connecting section facing away from the supporting section is connected to the island structure. The supporting section is embedded in the supporting area, and the shielding structure is arranged around the supporting section.

11. The hydrogen sensor according to any one of claims 1 to 6, characterized in that: The device further includes an insulating layer, wherein the insulating layer is located between the functional layer and the substrate layer, and the isolation trench penetrates the insulating layer.

12. The hydrogen sensor according to claim 11, characterized in that The insulating layer satisfies at least one of the following characteristics: The thickness of the insulating layer is 50-500 nm; The insulating layer is made of at least one of silicon dioxide, silicon nitride and a silicon dioxide / silicon nitride composite material.

13. The hydrogen sensor according to any one of claims 1 to 6, characterized in that: The gas-sensing structure includes a capacitor component and a resistor, and the resistor is located in the middle of the capacitor component.

14. The hydrogen sensor according to claim 13, characterized in that The capacitor assembly includes a hydrogen-sensitive capacitor and a reference capacitor, and the hydrogen-sensitive capacitor and the reference capacitor are symmetrically arranged relative to the resistor.

15. The hydrogen sensor according to claim 13, characterized in that The temperature control structure includes a heating coil and a temperature measuring coil. The heating coil is arranged on the outside of the capacitor component, and the temperature measuring coil is located in the middle of the heating coil.

16. The hydrogen sensor according to any one of claims 1 to 6, characterized in that: It also includes a passivation layer formed above the functional layer, the passivation layer covers the working area, and a window structure capable of at least partially exposing the gas-sensitive structure is provided on the passivation layer.

17. A method for preparing a hydrogen sensor, characterized in that: The preparation method comprises: Providing a substrate layer, the substrate layer comprising a support area and a functional area; forming a functional layer on one side of the substrate layer, wherein the functional layer includes a working area having a gas-sensing structure and a temperature-controlling structure; Based on the etching process, a cavity, a beam-island structure and at least one isolation groove on the peripheral side of the working area are formed in the functional area. The beam-island structure is located above the cavity and is used to support the working area. The isolation groove penetrates the functional layer and extends to the substrate layer to communicate with the cavity.

18. The preparation method according to claim 17, characterized in that: The step of forming the cavity, the beam island structure, and the at least one isolation trench located on the periphery of the working area in the functional area based on an etching process includes: forming the cavity and the substrate thin layer in the functional area based on an etching process, wherein the substrate thin layer is located between the cavity and the working area; The functional layer and the substrate thin layer are etched based on an etching process to form at least one isolation groove and the beam island structure penetrating the functional layer and the substrate thin layer, wherein the isolation groove penetrates the substrate thin layer and communicates with the cavity.

19. The preparation method according to claim 18, characterized in that: The formation process of the beam island structure includes: Forming the beam-island structure having a connected island structure and at least two beam structures based on an etching process; The beam island structure and the isolation groove are formed integrally. The beam structure is located between adjacent isolation grooves. The isolation grooves are located on the periphery of the island structure. The island structure is suspended above the cavity.

20. The preparation method according to claim 17, characterized in that: Before forming the functional layer, the preparation method includes: The substrate layer is locally ion-implanted based on a patterning process to form a shielding layer located at the periphery of the beam-island structure. The shielding layer can form a depletion layer between the beam-island structure and the supporting area.

21. The preparation method according to claim 17, characterized in that: Before forming the functional layer, the preparation method further comprises: An insulating layer is formed on one side of the substrate layer, and the isolation trench can penetrate the insulating layer.

22. The preparation method according to claim 17, characterized in that: The preparation method further comprises: forming a passivation layer on the functional layer, wherein the passivation layer covers the working area; A window structure is formed on the passivation layer, wherein the window structure can at least partially expose the gas-sensing structure.

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