Single-pass porous substrate of semiconductor gas sensor

Abstract

The invention relates to a single-pass porous substrate of a semiconductor gas sensor. The single-pass porous substrate comprises a functional region for detecting a sensing reaction of target detection gas based on a first temperature and a non-functional region for filtering at least part of impurity gas except the target detection gas based on the sensing reaction lower than the first temperature; the non-functional area is used for corner compensation when the functional area deforms in a high-temperature environment; the functional area and the non-functional area are connected through a plurality of suspensions to reduce heat loss of the functional area; the suspension can conduct heat on the functional area to the non-functional area in a heat conduction mode. The displacement trend of the functional area when the functional area expands under the heated condition can be limited under the tensile stress of the non-functional area connected with the functional area through the suspension, so that the functional area can be kept matched with a heating area for providing a heat source for the functional area. According to the invention, the proportion of impurity gas in the mixed gas entering the functional area can be reduced, so that the sensing efficiency is improved.

Description

[0001] The original basis of this divisional application is a patent application with the application number 202310383610.3, the application date of April 10, 2023, and the invention name of "a semiconductor gas sensor based on single-pass porous substrate", which claims the priority of a patent application with the application number 202310158176.9, the priority date of February 23, 2023. TECHNICAL FIELD

[0002] The present application relates to the field of sensor devices, in particular to a single-pass porous substrate of a semiconductor gas sensor. BACKGROUND

[0003] In recent years, the media frequently report sudden toxic gas leakage events, and people are paying more and more attention to detecting toxic gas leakage. Toxic gases such as carbon monoxide, hydrogen sulfide, carbon dioxide, and sulfur dioxide can cause significant harm to the human body. However, due to the long testing time of traditional toxic gas detection methods, the need for professional personnel to operate the testing instrument, the complicated operation, and the difficulty in on-site use, etc., it cannot be effectively promoted. Generally, non-professional personnel need to use toxic gas detection devices. In order to be able to quickly detect toxic gases in a larger area, it is required that the toxic gas detection device must have the characteristics of fast response speed, simple operation, miniaturization, and portability.

[0004] Gas sensors, especially metal oxide semiconductor (MOX) based resistive gas sensors, are widely used in environmental pollution monitoring, hazardous gas leakage, chemical detection, and other production and life fields. With the development of Internet of Things technology and the promotion of precision medical strategy, traditional MOX gas sensors have great application potential in emerging fields such as wearable portable devices, point-of-care testing devices (POCT), smart cities, and smart homes, but also face many challenges.

[0005] CN105900236A discloses a semiconductor sensor device comprising: a substrate; a non-conformal seed layer located above the substrate; at least one electrode located above the non-conformal seed layer; and a porous sensing layer directly supported by the non-conformal seed layer and in electrical communication with the at least one electrode, the porous sensing layer defining a plurality of grain boundaries formed using atomic layer deposition by spaced apart nucleation on the non-conformal seed layer.

[0006] CN113092542A discloses a planar nanometer gas sensor, array and preparation method thereof, and relates to the technical field of gas sensors. The gas sensor comprises, from top to bottom, a planar sensing electrode, a sensing layer, an electrically insulating layer and a micro-heater. The sensing layer is formed after depositing a nanometer sensing material in a double-hole type substrate. The double-hole type substrate is composed of a plurality of double-hole type nanotubes. The double-hole type nanotube is a nanotube with openings at both ends and a communication between the two ends. The nanometer sensing material is deposited on the wall of the double-hole type nanotube. The heating area of the micro-heater overlaps the sensing area of the planar sensing electrode in the vertical direction.

[0007] Most of the MOX gas sensors on the market have the disadvantages of high power consumption and poor selectivity. Gas sensors are mostly planar two-dimensional thin film structures and need to operate at high temperatures (300-400℃). The adsorption capacity between the sensor and the target gas is activated by heating to improve the response sensitivity to the gas. This makes these gas sensors unsuitable for low-power application scenarios and also faces challenges in long-term stability and service life. In addition, with the rapid development of today's society, wireless connection technology, network technology and electronic technology are increasingly combined, and the requirements for intelligence and humanization are also increasing. Combining gas sensors with wireless connection technology and network technology greatly facilitates the simultaneous detection and real-time monitoring of toxic gases, making it easier for people to detect toxic gases in a timely manner. Therefore, it is of great significance to manufacture a miniature, reliable, portable, high-sensitivity detection system that can monitor different toxic gases in real time.

[0008] In addition, on the one hand, there are differences in understanding of those skilled in the art; on the other hand, the inventors have studied a large number of literatures and patents when making the invention, but due to space limitations, all details and contents are not listed in detail. However, this does not mean that the present invention does not have these prior art characteristics. On the contrary, the present invention already has all the characteristics of the prior art, and the applicant reserves the right to add relevant prior art in the background art. SUMMARY

[0009] To solve at least one of the above problems in the prior art, the application provides a semiconductor gas sensor based on a single-pass porous substrate, which at least includes a sensing layer. The sensing layer can be divided into a functional area for detecting the sensing reaction of the target detection gas at a first temperature and a non-functional area for filtering at least part of the impurity gas other than the target detection gas based on the sensing reaction at a temperature lower than the first temperature. The functional area and the non-functional area are connected by a plurality of suspensions, wherein the suspensions can conduct heat from the functional area to the non-functional area by heat conduction. Studies have shown that even if the heat generated by the heating electrode is mostly concentrated and radiated to the functional area, the non-functional area forms a temperature field with a higher temperature the closer it is to the suspension connection and the heating electrode under the combined action of the remaining heat radiated by the heating electrode and the heat conducted by the suspensions. The second temperature at the highest point of the temperature field is lower than the first temperature due to heat loss during heat transfer. Therefore, the non-functional area can also form a sensing reaction for some gas molecules that do not require high temperature conditions (such as hydrogen and carbon monoxide). When the target molecule to be detected requires a high temperature, some impurity gases that do not require high temperature conditions will also enter the functional area and affect the sensing result. By applying different temperatures to the non-functional area and the functional area, the impurity gas can be removed when it enters the non-functional area and the proportion of impurity gas in the mixed gas entering the functional area is reduced, thereby improving the sensing efficiency.

[0010] Preferably, the sensing layer can adjust the number of suspensions based on the relationship between the first temperature at which the target detection gas occurs sensing reaction and the second temperature at which the impurity gas occurs sensing reaction, wherein the number of suspensions decreases as the difference between the second temperature and the first temperature increases, and the minimum number of suspensions is 1. The more suspensions there are, the more heat they can conduct to the non-functional area, and the higher the overall temperature of the non-functional area, and the higher the maximum temperature it can reach. When the impurity gas requires a high temperature for sensing reaction, even close to the first temperature at which the target detection gas occurs sensing reaction, in order to ensure that the impurity gas can be sensed and filtered in the non-functional area, the temperature of the non-functional area can be increased by increasing the number of suspensions. When the second temperature at which the impurity gas occurs sensing reaction is higher than the first temperature, the maximum temperature that the sensor can reach is not enough for the impurity gas to occur sensing reaction, so it will not affect the sensing result. In addition, the area of the non-functional area is larger than the area of the functional area in the application, which makes it easier for the non-functional area to filter and exclude the impurity gas.

[0011] Preferably, the suspension is connected to one end of the functional area at a corner away from the geometric center of the functional area, so that the heat conducted to the non-functional area by the suspension is mostly from the edge position away from the core position of the functional area, and the two connecting angles formed by the suspension and the functional area are obtuse, so that the deformation degree of the connecting angle is consistent when the connecting angle is heated and expanded. The connecting angle with an obtuse angle can be deformed without limitation when the connecting angle is heated and expanded, thereby reducing the fracture of the connecting part due to the large thermal stress. In the present application, the two connecting angles of the connecting part are set to the same size, which further avoids the problem that the left and right connecting parts are broken due to the different angles and the unbalanced thermal stress.

[0012] Preferably, the displacement trend of the functional area when it is expanded under the condition of being heated can be limited by the tensile stress of the non-functional area connected to the functional area by the suspension, so that the functional area can match the heating area providing the heat source for the functional area. The expansion effect of the functional area when it is heated causes the displacement of the functional area, and the higher the temperature, the greater the displacement. After the displacement of the functional area, it no longer matches the heating area, which easily causes the non-uniform heating of the functional area and poor sensing effect. In order to avoid this problem, the functional area is connected to the non-functional area by the suspension, and the displacement of the functional area is limited by the non-functional area being fixed or by the friction of the non-functional area, so that the functional area always stays in the heating area and ensures the normal sensing reaction of the functional area.

[0013] Preferably, the sensing layer can be formed by a single-pass porous substrate with sensing particles deposited on the surface. In particular, one specific example of the single-pass porous substrate can be a single-pass porous aluminum oxide substrate. Specifically, the single-pass porous aluminum oxide substrate can be formed by arranging a plurality of single-hole nanotubes, the nanotubes having one opening communicating with the outside, the other end of the nanotube relative to the opening being connected to the aluminum base through a blocking layer, and the sensing particles being deposited in the nanotube and near the opening side of the nanotube.

[0014] Preferably, the semiconductor sensor further comprises a sensing electrode, the sensing electrode being arranged on the side of the functional area with the opening, the sensing electrode comprising at least a pair of interdigital electrodes, the interdigital electrodes being electrically connected to the sensing particles deposited on the functional area, and the electrical change of the sensing particles when they have a sensing reaction being transmitted based on the sensing electrode under the condition of an external voltage source.

[0015] Preferably, the semiconductor sensor further comprises a heating layer and an isolation layer, the isolation layer being arranged between the heating layer and the sensing layer, the isolation layer being capable of uniformly transmitting the heat generated by the heating layer to the non-functional area, and the isolation layer being pre-provided with a heating electrode hole position for leading the heating layer to an external heating power source.

[0016] Preferably, the heating layer comprises a heating electrode and a heat resistance wire, the heating electrode is electrically connected with the heat resistance wire through a connecting wire, the shape of the heating electrode matches the heating electrode hole site, so that the heating electrode can be arranged in the heating electrode hole site in a nested manner and maintain electrical connection with the external heating power supply, wherein the shape of the heating area formed by the meandering heat resistance wire matches the functional area, so that the heat resistance wire can heat the functional area as a whole.

[0017] Preferably, the sensor further comprises a support layer, the support layer is arranged on the other side of the heat resistance wire relative to the sensing layer, the support layer is provided with a bearing area for preventing heat generated by the heat resistance wire from dissipating from the side of the support layer, and the bearing area is arranged to match the heating area formed by the heat resistance wire.

[0018] Preferably, the sensor further comprises a substrate, the substrate is arranged on the other side of the support layer, and the substrate is provided with a notched hole penetrating through the substrate, the notched hole can improve the bending resistance of the substrate. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a schematic diagram of the overall structure of the present application;

[0020] Figure 2 is a schematic diagram of the sensing electrode of the present application;

[0021] Figure 3 is a schematic diagram of the heating layer of the present application;

[0022] Figure 4 is a schematic diagram of the sensing layer partition of the present application;

[0023] Figure 5 is a sectional view of the sensing layer of the present application.

[0024] LIST OF REFERENCE NUMBERS

[0025] 1: sensing electrode; 11: interdigital electrode; 12: interdigital interval; 13: interdigital end; 14: interdigital panel; 2: sensing layer; 21: functional area; 22: non-functional area; 23: suspension; 24: hole; 25: aluminum base; 26: oxide layer; 27: barrier layer; 3: sensing particle; 4: isolation layer; 41: first overlapping area; 42: heating electrode hole site; 5: heating layer; 51: heating electrode; 52: connecting wire; 53: heat resistance wire; 6: support layer; 61: second overlapping area; 7: substrate; 71: notched hole. DETAILED DESCRIPTION

[0026] The present application will be described in detail below with reference to the accompanying drawings.

[0027] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0028] The present application provides a single-pass porous substrate-based semiconductor gas sensor, which can include the following parts stacked from top to bottom as shown in the figure: Figure 1

[0029] A sensing electrode 1 is arranged at the top of the whole sensor, for transmitting the electrical signal when the sensor generates a sensing reaction.

[0030] A sensing layer 2 is arranged under the sensing electrode 1 in a way that it at least partially vertically overlaps the sensing electrode 1, and has sensing particles 3 for generating a sensing reaction with the gas to be detected.

[0031] An isolation layer 4 is arranged on the side of the sensing layer 2 opposite to the sensing electrode 1, for uniformly and stably transmitting the heat required for the sensing reaction of the sensing particles 3 to the sensing layer 2.

[0032] A heating layer 5 is arranged under the isolation layer 4, for providing heat to the sensing layer 2, which can be uniformly conducted to the sensing layer 2 after being blocked by the isolation layer 4.

[0033] A support layer 6 is arranged on the side of the heating layer 5 opposite to the isolation layer 4, for preventing the heat generated by the heating layer 5 from being lost on the side of the support layer 6.

[0034] A substrate 7 is arranged at the bottom of the whole sensor structure, as a carrier structure, for carrying all the above layers. According to a preferred embodiment, in combination with Figure 1 and Figure 5 The sensing electrode 1 is arranged on the surface of the sensing layer 2, and the sensing electrode 1 is in contact with and electrically connected to the sensing particles 3 on the sensing layer 2. When the sensing particles 3 are in contact with the gas to be detected that can generate a sensing reaction with the sensing particles 3, the sensing particles 3 can generate a sensing reaction under the premise that the voltage across the sensing electrode 1 is constant, so that the resistance of the sensing particles 3 changes, and further changes the current size of the circuit. By monitoring the current change in the circuit, it can be determined whether there is a gas in the scene of the sensor that can generate a sensing reaction. Preferably, as shown in Figure 2 ​As shown, the sensing electrode 1 is composed of a pair of interdigital electrodes 11 which match the functional area 21 of the sensing layer 2 in combined shape. The interdigital electrodes 11 are symmetrically arranged without contact, and the interdigital area 12 between the two interdigital electrodes 11 is electrically connected to the interdigital end 13 of the interdigital electrodes 11 through the sensing particles 3 on the sensing layer 2, so that a closed loop is formed between the two interdigital electrodes 11. Specifically, the interdigital electrodes 11 are configured to extend two branch wires from the two parallel wires at the proximal end position. Optionally, the number of branch wires can be any value greater than two.

[0035] According to a preferred embodiment, the sensing electrode 1 is deposited on the surface of the sensing layer 2. In particular, one specific example of the sensing layer 2 can be a single-pass porous alumina substrate. Specifically, the single-pass porous alumina substrate has its pore direction towards the sensing electrode 1, and the interdigital area 12 formed by the two interdigital electrodes 11 symmetrically embedded with each other is deposited at the pore position of the single-pass porous alumina substrate. The two interdigital electrodes 11 are electrically connected by contacting the sensing particles 3 in the interdigital area 12 after being deposited on the surface of the sensing layer 2. The sensing particles 3 in the interdigital area 12 include sensing particles 3 on the surface outside the pore and sensing particles 3 deposited on the inner wall of the single-pass porous alumina substrate inside the pore. Preferably, the interdigital area 12 can be a region of any shape that can be thought of by those skilled in the art, and the interdigital electrodes 11 matched therewith enclose a contour matching the interdigital area 12. Here, it is set to be triangular. The two interdigital electrodes 11 are led out through respective interdigital panels 14, which are used to connect to an external voltage source.

[0036] According to a preferred embodiment, the sensing layer 2 can be formed by a single-pass porous alumina substrate with sensing particles 3 deposited on the surface. It should be understood that the single-pass porous alumina substrate described in the present application is only a preferred specific example of the sensing layer 2. In some alternative embodiments, the single-pass porous substrate or the sensing layer 2 described in the present application can also be formed by one or more of titanium oxide, silicon oxide, tantalum oxide, zirconium oxide or gallium nitride.

[0037] According to a preferred embodiment, taking the single-pass porous alumina substrate as an example, the single-pass porous alumina substrate can be composed of a plurality of single-hole nanotubes, which have an opening communicating with the outside. In particular, in addition to the single-pass porous structure, the alumina substrate can also be a porous double-pass structure, i.e. a double-pass alumina substrate composed of a plurality of two openings communicating with each other. The common structure of the single-pass porous alumina substrate is honeycomb, which is composed of hundreds, thousands or even tens of thousands of hexagonal columnar oxide units. Figure 5As shown, each regular hexagon has a circular channel 24 in the middle. The size of the channel 24 is generally in nanometer level, and the channel 24 is generally perpendicular to the surface, with uniform and relatively adjustable aperture size, simple structure and ordered array. There is a barrier layer 27 between the aluminum base 25 and the oxide layer 26, in the shape of a hemisphere. This special structure makes the single-through multi-hole aluminum oxide substrate simple in the preparation process of the nano-ordered array, low in price, and suitable for the assembly of various materials. The ratio between the morphology of the deposited substance and particles in the single-through multi-hole aluminum oxide substrate and the performance of the nano-materials is closely related. The single-through multi-hole aluminum oxide substrate can be prepared by two-part anodization. Due to the characteristics of high temperature resistance, high strength, and single-dispersion of the aperture, the substrate becomes an ideal preparation method of nano-aluminum oxide materials.

[0038] According to a preferred embodiment, the sensing particles 3 are nano-zinc oxide materials. Preferably, the sensing particles 3 can also be gas-sensitive materials such as tin dioxide or tungsten trioxide (a gas can cause the electrical properties of the gas-sensitive material to change, such as an increase or decrease in resistance, when the gas-sensitive material is in contact with the gas). The sensing particles 3 are deposited by adsorption in the inner wall of the nanotube and the surface layer of the nanotube aperture of the single-through multi-hole substrate. The single-through multi-hole substrate has a high specific surface area, can contact and adsorb as many sensing particles 3 as possible, and greatly increases the spreading area of the sensing particles 3, so that the to-be-detected gas molecules can more easily contact the sensing particles 3 and react with them.

[0039] According to a preferred embodiment, when the sensing particles 3 contact the to-be-detected gas molecules that can have a sensing reaction, the to-be-detected gas can gain or lose electrons based on its oxidizing and reducing properties, at which time the electrical properties of the sensing particles 3, such as resistance, will change, the current passing through will also change, and the current size on the sensing electrode 1 electrically connected to the sensing particles 3 will also change. Therefore, by monitoring the degree of change in the current, it can be determined whether the sensing particles 3 contact the to-be-detected gas molecules that can have a sensing reaction with them, and by controlling the temperature environment, it can be controlled that the sensing particles 3 only have a sensing reaction with the target molecules that need to be detected.

[0040] As Figure 4The single-pass porous substrate of the sensing layer 2 can be divided into a functional area 21 and a non-functional area 22. The functional area 21 and the non-functional area 22 are connected by a suspension 23. The sensing particles 3 are deposited on both the functional area 21 and the non-functional area 22. The shape of the functional area 21 is adapted to the shape of the sensing electrode 1, so that the shape of the functional area 21 can match the interdigital area 12. Here, the shape of the functional area 21 is set as a triangle matching the profile of the sensing electrode 1. The non-functional area 22 is used for corner compensation of the functional area 21 when deformation occurs in a high-temperature environment. Only one suspension 23 is connected to the functional area 21, which can reduce the heat loss of the functional area 21. The functional area 21 needs to be at a relatively high temperature, referred to as the first temperature, when a sensing reaction occurs. Due to the differences in Young's modulus and thermal expansion coefficient of the materials constituting the functional area 21, the sensing electrode 1 and the isolation layer 4 stacked on both sides, the surface stress of the functional area 21 will become larger and larger under high-temperature conditions. The stress at the position connected to the suspension 23 is relatively large, which is prone to rupture and damage. The corner compensation can be used to improve it. The non-functional area 22, the suspension 23 and the functional area 21 are integrally formed. Preferably, the non-functional area 22, the suspension 23 and the functional area 21 can be cut and separated from the complete single-pass porous substrate by cutting.

[0041] According to a preferred embodiment, the sensing current mainly distributes on the sensing particles 3 when the sensing reaction occurs, including the sensing particles 3 on the surface of the substrate pore and in the substrate nanopore. In the present application, the contact surface of the sensing electrode 1 and the sensing layer 2 is the overlapping area of the interdigital area 12 of the sensing electrode 1 and the functional area 21 of the sensing layer 2, that is, the area where the sensing reaction occurs is mostly concentrated on the nanopore wall with a higher developed area, and a small part is located in the interdigital area of the sensing electrode 1.

[0042] According to a preferred embodiment, the isolation layer 4 is arranged at the bottom layer of the sensing layer 2, and is used to isolate the sensing layer 2 from the heating layer 5. The isolation layer 4 is used to prevent the sensing particles 3 from being disabled due to the rapid temperature change of the heating layer 5, and the rapid temperature change will cause the large change in thermal stress and the large change in thermal expansion of the device, which is prone to cause deformation and rupture of the material. The isolation layer 4 can not only conduct heat, but also keep the sensing layer 2 and the heating layer 5 electrically isolated. The isolation layer 4 can be formed by processing a silicon oxide layer structure.

[0043] According to a preferred embodiment, the isolation layer 4 is provided with a first overlapping area 41 matched with the functional area 21, the suspension 23 and the interdigital electrode 11 for connecting the wires of the interdigital panel 14 part. As shown in FIG. 1, the first overlapping area 41 is arranged on the isolation layer 4, and is connected to the functional area 21 and the suspension 23. The first overlapping area 41 is used to connect the wires of the interdigital panel 14 part. The wires of the interdigital panel 14 part are connected to the wires of the interdigital electrode 11 through the first overlapping area 41. The wires of the interdigital panel 14 part are connected to the wires of the interdigital electrode 11 through the first overlapping area 41. Figure 1As shown, the first overlapping area 41 is formed by cutting away several trapezoids from the isolation layer, which are intersected at a point and have their short sides facing each other. In the present application, three trapezoids are cut away to form the first overlapping area 41. The triangle area enclosed by the trapezoids matches the shape of the functional area 21, and the area of the triangle area is slightly larger than that of the functional area 21, so as to ensure that the functional area 21 is completely within the triangle area. The reserved area between adjacent trapezoids is reserved for matching and overlapping with the partial wires of the suspension 23 and the interdigital electrode 11.

[0044] According to a preferred embodiment, the heating layer 5 is arranged on one side of the isolation layer 4 relative to the sensing layer 2. As shown, Figure 3 As shown, the heating layer 5 includes a heating electrode 51 and a heat resistance wire 53. The heat resistance wire 53 is connected to the heating electrode 51 through a connecting wire 52. The present application mainly provides the heat source required for the sensing reaction of the entire sensor by the heat resistance wire 53. The heat resistance wire 53 is formed by a material with relatively high electrical resistivity and is coiled to match the triangle area of the first overlapping area 41, so that the heat resistance wire 53 can have a relatively long length to concentrate the heat on the functional area 21 of the sensing layer 2 under the premise of a certain overall shape. The material of the connecting wire 52 can be the same as that of the heat resistance wire 53, that is, the connecting wire 52 will also generate heat when the current passes through, but since the heat resistance wire 53 has a relatively long heat generation length, the heat is relatively concentrated, and therefore the heat generated by the connecting wire 52 has little effect on the sensing reaction of the functional area 21. The heat resistance wire 53 and the connecting wire 52 can be integrally formed, which brings the highest economic benefit without the need to select other wires to be electrically connected to the heat resistance wire 53, and saves material loss in the manufacturing process. The connecting wire 52 is led out to the heating electrode 51 by overlapping into the reserved area. The heating electrode 51 is preferably in a rectangular structure, and the heating electrode 51 has a relatively large area so as to be easily connected to the voltage source. The heating electrode 51 is nested on the isolation layer 4 through the heating electrode hole 42 reserved on the isolation layer 4, so that one side of the heating electrode 51 is in an exposed environment, facilitating the connection of the heating voltage source.

[0045] According to a preferred embodiment, the heating area formed by the coiled heat resistance wire 53 matches the shape of the functional area 21, so that the heat resistance wire 53 can heat the functional area 21 as a whole. The heat generated by the heat resistance wire 53 can be collected in the isolation layer 4 and uniformly conducted to the functional area 21 on the side of the isolation layer 4 when passing through the isolation layer 4, so that the heat generated by the heat resistance wire 53 will not directly act on the functional area 21, avoiding the imbalance of thermal stress caused by the uneven heating of the functional area 21, which leads to the deformation of the functional area 21 or the shedding of the sensing particles 3 on the functional area 21.

[0046] According to a preferred embodiment, the support layer 6 is arranged at the bottom of the heating layer 5. The support layer 6 is provided with a second overlapping area 61 corresponding to the position of the first overlapping area 41. The second overlapping area 61 is sized and shaped to match the first overlapping area 41. The second overlapping area 61 is used as a bearing area for the heat resistance wire 53 when the heating layer 5 is deposited on the support layer 6. The second overlapping area 61 includes three cantilever beams for connecting to the remaining area of the support layer 6. When the heat generated by the heating layer 5 is transferred to the bearing area, the bearing area is only connected by the three cantilever beams, and the heat on the bearing area is slowly dissipated through the cantilever beams, so that the bearing area can concentrate the heat radiated by the heating layer 5 to the support layer 6, and the temperature of the functional area 21 adapted to the first overlapping area 41 and the second overlapping area 61 can reach the first sensing temperature. The support layer 6 can be formed by grooving a silicon nitride or silicon oxide layer structure.

[0047] According to a preferred embodiment, the substrate 7 is located at the bottom of the entire sensor device to improve the overall physical strength of the sensor. As shown in Figure 1 , the substrate 7 is a cubic structure with a relatively high thickness. The substrate 7 is provided with a through-slot hole 71 extending vertically through the entire substrate 7. In the present application, the through-slot hole 71 is shaped as a triangular structure with high stability. Preferably, the shape of the through-slot hole 71 can also be square, trapezoidal, or any other shape that can be thought of by those skilled in the art. By grooving the substrate 7, the bending resistance of the substrate 7 can be increased, further avoiding the risk of bending of the sensor device when it falls, thereby further improving the use reliability of the sensor device.

[0048] The shape of the through-slot hole 71 matches the first overlapping area 41 and the second overlapping area 61, and the size of the triangular through-slot hole 71 is larger than the first overlapping area 41, so that the sensor device passes through the through-slot hole 71, the second overlapping area 61, the heat resistance wire 53, the first overlapping area 41, and the sensing layer 2 in turn from bottom to top. The to-be-detected gas can enter from one side of the sensor device and pass out from the other side, and the gas flowability of the device is strong, making it easier for the to-be-detected gas to enter for detection. Preferably, in order to provide higher physical strength, the substrate 7 can preferably be a silicon substrate. In particular, when the substrate 7 of the present application is prepared from silicon material, as shown in Figure 1 , the support layer 6 can not be necessary. When the substrate 7 is selected from one or more of sapphire, gallium nitride, or silicon carbide, Figure 1 , the support layer 6 is generally necessary, considering the electrical insulation between the substrate 7 and other layer structures.

[0049] According to a preferred embodiment, the non-functional area 22 of the sensing layer 2 is connected to the functional area 21 by a suspension 23. When the functional area 21 is heated by the heating of the thermal resistance wire 53, due to the difference in the Young's modulus and the thermal expansion coefficient of the materials of each layer, the functional area 21 of the sensor will have a large thermal stress and deformation at high temperature. When the thermal stress is too large, it will affect the stability of the sensor, and even cause the suspension 23 to break at the connection, the film structure formed by the sensing particles 3 to crack, and other problems, directly affecting the reliability and life of the sensor. Due to the existence of thermal stress when the functional area 21 is heated, the functional area 21 will deform and displace during thermal expansion, and the higher the temperature, the greater the deformation and displacement. When the highest temperature is 500 degrees Celsius, the displacement of the functional area 21 can reach 1.5 um. Under the condition of long-term thermal deformation, the position of the functional area 21 will inevitably change to not overlap with the first overlap area 41 where the heating electrode 51 is located, and the heat generated by the heating electrode 51 can only heat part or a small part of the functional area 21, making the temperature distribution on the functional area 21 uneven, further causing the film structure on the functional area 21 to fall off and fail. The present application fixes the position of the functional area 21 by connecting the functional area to the non-functional area 22 using a suspension 23 and connecting the non-functional area 22 to the isolation layer 4. When the functional area 21 is heated and expands and deforms, its displacement trend is limited by the non-functional area 22 through the suspension 23, so that it always remains in the position matched with the heating electrode 51.

[0050] The non-functional area 22 can receive heat radiated from the heating electrode 51 through the trapezoidal slot portion on the isolation layer 4 to the non-functional area 22 and heat transferred from the functional area 21 to the non-functional area 22 through the suspension 23, so that a second temperature required for the sensing reaction to occur on the upper part of the non-functional area 22 can be reached. The highest temperature that the second temperature can reach is lower than the first temperature at which the sensing reaction occurs in the functional area 21. The sensing particles 3 can have sensing reactions with different types of gas molecules to be detected at different temperatures. For example, the catalytic ignition temperature of methane is usually higher than 400 degrees Celsius, while the catalytic ignition temperature of hydrogen, carbon monoxide or other alkanes is usually lower than 260 degrees Celsius. Studies have shown that even if most of the heat generated by the heating electrode 51 is concentrated and radiated to the functional area 21, the non-functional area 22 forms a temperature field with a higher temperature closer to the connection of the suspension 23 and the heating electrode 51 under the combined action of the remaining heat radiated by the heating electrode 51 and the heat transferred from the functional area 21 through the suspension 23. The second temperature at the highest point of the temperature field is lower than the first temperature due to heat loss during heat transfer, and the overall temperature reaches 300 degrees Celsius. Therefore, the non-functional area 22 can also form a sensing reaction for some gas molecules that do not require high temperature conditions (such as hydrogen and carbon monoxide). When the target molecules to be detected require a higher temperature, some impurity gases that do not require high temperature conditions will also enter the functional area 21 and have a sensing reaction, affecting the sensing result. By applying different temperatures to the non-functional area 22 and the functional area 21, the impurity gases can enter the non-functional area 22 and have a sensing reaction to be removed, reducing the proportion of impurity gases in the mixed gas entering the functional area 21, thereby improving the sensing efficiency. Further, the area of the non-functional area 22 is much larger than that of the functional area 21, so that the non-functional area 22 can more easily contact the impurity gases in the mixed gas and remove the impurity gases based on the sensing reaction. Some impurity gases that can have a sensing reaction on the non-functional area 22 are adsorbed on the non-functional area 22 in the form of a sensing reaction when they enter the sensor, so that the proportion of the gas to be detected in the mixed gas entering the sensor increases, thereby increasing the probability of the functional area 21 having a sensing reaction with the gas to be detected, and the sensitivity of the sensor is improved.

[0051] Specifically, when there is a mixed gas of methane, hydrogen and carbon monoxide in the environment where the sensor is arranged, but only the presence of methane needs to be detected. In this case, in order to ensure that the sensing particles 3 in the sensor can react with methane, the functional area 21 needs to be heated to 400 degrees Celsius, but hydrogen and carbon monoxide will also react with the sensing particles 3, thereby affecting the measurement of the sensing current. In the present application, the non-functional area 22 is added, which is heated only by using the dissipated heat to reach the temperature required for the sensing reaction of hydrogen or carbon monoxide, so as to filter hydrogen and carbon monoxide, and the sensing area of the non-functional area 22 that can react with hydrogen and carbon monoxide is much larger than that of the functional area 21, so the non-functional area 22 can more easily contact hydrogen and carbon monoxide and react with them. The non-functional area 22 does not need to be heated by adding an additional heat source, and the non-functional area 22 also does not need to add an additional electrode plate to detect the sensing current, further improving the utilization rate of heat.

[0052] Preferably, when the sensing current of hydrogen and carbon monoxide needs to be detected under certain specific factors, an electrode can be deposited in the non-functional area 22 for detection, so that the non-functional area 22 serves as another form of functional area 21. Preferably, different areas can be divided into functional areas 21 based on the temperature distribution of the temperature field on the non-functional area 22, so as to realize the detection of different gas species at different temperatures on the same sensing layer 2. The core area functional area 21 measures the gas with a high temperature required for sensing reaction, and the non-functional area 22 sets the functional area 21 with decreasing temperature required for sensing reaction from inside to outside.

[0053] According to a preferred embodiment, when the sensor is packaged, the channel through which the mixed gas enters the inside of the sensor can be arranged around the non-functional area 22, so that the mixed gas flows over the non-functional area 22 from around the non-functional area 22 to the functional area 21, encouraging the mixed gas to enter the functional area 21 with some impurity gases removed in the non-functional area 22.

[0054] According to a preferred embodiment, since the heat radiation rate of heat conduction through air is much smaller than the heat conduction rate through the suspension 23, the overall temperature change of the temperature field on the non-functional area 22 mainly depends on the heat directly transferred to the non-functional area 22 by the suspension 23 in the form of heat conduction. In a conventional suspension design, in order to reduce the loss of heat on the functional area 21, the number of suspensions 23 is usually reduced as much as possible to reduce the heat conduction loss of the functional area 21 along the suspension 23. Further, when the number of suspensions 23 cannot be reduced, the suspension 23 is improved to be designed as a slender support beam structure. In the present application, the heat transferred to the non-functional area 22 along the suspension 23 provides the sensing particles 3 of the non-functional area 22 with the required heat for sensing to reach the sensing temperature, so it is not necessary to reduce the number of suspensions 23 or adjust the suspension 23 to a slender structure, further reducing the workload when the width of the suspension 23 needs to be refined and reducing material loss.

[0055] According to a preferred embodiment, referring to Figure 4 , in order to ensure that the heat transferred to the non-functional area 22 through the suspension 23 can meet the heat required by the non-functional area 22 during the filtering process of impurity gas, as many suspensions 23 as possible should be provided on the functional area 21 to connect to the non-functional area 22, but setting more suspensions 23 will make the heat on the functional area 21 conduct out too fast, so that the functional area 21 cannot reach the first temperature or requires a higher power heating electrode 51 to reach the first temperature. Therefore, while increasing the number of suspensions 23, the temperature change trend of the functional area 21 should also be considered.

[0056] Preferably, the suspension 23 is provided to connect to the non-functional area 22 at each corner of the functional area 21 farthest from the core position (geometric center) of the functional area 21, which can increase the heat conducted from the functional area 21 to the non-functional area 22 while as much as possible reducing the impact on the temperature of the functional area 21, to expand the overall temperature gradient of the temperature field on the non-functional area 22 and the radiation range of the temperature field, so that the non-functional area 22 can filter impurity gas in the environment, further improving the sensing sensitivity of the functional area 21.

[0057] Further, the minimum temperature required by the temperature field on the non-functional area 22 can be determined based on the nature of the impurity gas, and the number of the suspensions 23 can be adjusted according to the range of the first temperature on the functional area 21 determined based on the nature of the target detection gas. When the sensing temperature of the impurity gas is much lower than the sensing temperature of the target detection gas, i.e. the minimum temperature required by the temperature field is much lower than the first temperature, the non-functional area 22 does not need the functional area 21 to conduct too much heat to reach the temperature required by the impurity gas filtration, and at this time, the number of the suspensions 23 is reduced to reduce the heat loss on the functional area 21 to achieve the purpose of energy saving. When the minimum temperature required by the temperature field is close to the first temperature, the non-functional area 22 needs to transfer a large amount of heat from the functional area 21 via the suspensions 23, and therefore the number of the suspensions 23 needs to be increased so that each corner of the functional area 21 is provided with a suspension 23 connected to the non-functional area 22, especially when the number of the corners of the functional area 21 is more, the maximum temperature on the temperature field can be infinitely close to the first temperature on the functional area 21.

[0058] According to a preferred embodiment, the suspensions 23 are connected to one end of the functional area 21 to divide the corners of the functional area 21 in an equal manner, which can make the connection angles formed between the suspensions 23 and the two edges of the functional area 21 at the connection position the same, and reduce the risk of thermal stress unevenness and fracture due to the different connection angles of the connection position. Further, the connection angles formed between the suspensions 23 and the two edges of the functional area 21 at the connection position are obtuse angles, which further avoids the risk of fracture of the acute angle side due to the limitation of the thermal expansion trend when the connection angle is acute.

[0059] It should be noted that the above specific embodiments are exemplary, and those skilled in the art can think of various solutions under the inspiration of the disclosure of the present application, and these solutions also belong to the disclosed range of the present application and fall within the protection scope of the present application. Those skilled in the art should understand that the specification and drawings of the present application are illustrative and do not constitute a limitation on the claims. The protection scope of the present application is defined by the claims and their equivalents.

Claims

1. A single-pass porous substrate for a semiconductor gas sensor, characterized by, The single-pass porous substrate includes a functional area (21) for detecting the sensing reaction of the target detection gas at a first temperature and a non-functional area (22) for filtering at least part of the impurity gas other than the target detection gas based on the sensing reaction at a temperature lower than the first temperature, and the non-functional area (22) is used for corner compensation of the functional area (21) when the functional area (21) is deformed in a high-temperature environment; The functional area (21) and the non-functional area (22) are connected by a plurality of suspensions (23) to reduce heat loss of the functional area (21); the suspensions (23) can conduct heat on the functional area (21) to the non-functional area (22) by heat conduction; The displacement trend of the functional area (21) when it expands under the heated condition can be limited under the tensile stress of the non-functional area (22) connected to the functional area (21) through the suspensions (23), so that the functional area (21) can remain matched with the heating area providing the heat source of the functional area (21).

2. The one-pass porous substrate of claim 1, wherein, The end of the suspension (23) connected to the functional area (21) is arranged at an edge away from the geometric center of the functional area (21), so that the heat conducted by the suspension (23) to the non-functional area (22) is mostly from the edge position away from the core position of the functional area (21).

3. The one-pass porous substrate according to claim 1 or 2, wherein The number of the suspensions (23) is continuously reduced as the difference between the second temperature at which the sensing reaction of the impurity gas occurs and the first temperature at which the sensing reaction of the target detection gas occurs increases, and the minimum number of the suspensions (23) is 1.

4. The one-pass porous substrate according to any one of claims 1 to 3, wherein, The included angle between the two connection angles formed by the suspensions (23) and the functional area (21) is obtuse, so that the deformation degree of the connection angles when they are heated and expanded is consistent.

5. The one-pass porous substrate according to any one of claims 1 to 4, wherein, The end of the suspension (23) connected to the functional area (21) is connected to the functional area (21) in a way that equally divides the edges of the functional area (21), so that the connection angles formed between the suspension (23) and the two edges of the functional area (21) at the connection position are the same, reducing the probability of uneven thermal stress and fracture caused by different connection angle.

6. The one-pass porous substrate according to any one of claims 1 to 5, wherein, The single-pass porous substrate is formed by arranging a plurality of single-hole nanotubes, the nanotubes have an opening communicating with the outside, and sensing particles (3) are deposited in the nanotube and on the opening side of the nanotube; The sensing electrode (1) is arranged on the side of the functional area (21) opening of the channel (24); The functional area (21) is matched with the shape of the heating area formed by the serpentine of the heat-resistant wire (53) of the heating layer (5), so that the heat-resistant wire (53) can heat the functional area (21) as a whole.

7. The one-pass porous substrate according to any one of claims 1 to 6, wherein The sensing electrode (1) is arranged on the side of the functional area (21) with the opening; The sensing electrode (1) includes a pair of interdigital electrodes (11), the interdigital electrodes (11) are electrically connected with the sensing particles (3) deposited on the functional area (21), and the electrical change of the sensing particles (3) when they occur sensing reaction can be transmitted based on the sensing electrode (1) under the condition of an external voltage source.

8. The one-pass porous substrate according to any one of claims 1 to 7, wherein, The single-pass porous substrate is provided with an isolation layer (4) between the single-pass porous substrate and the heating layer (5), The isolation layer (4) transmits the heat generated by the heating layer (5) to the non-functional area (22) in a uniform conduction manner, and the isolation layer (4) is provided with a heating electrode hole position (42) for leading out the heating electrode of the heating layer (5) to an external heating power supply.

9. The one-pass porous substrate according to any one of claims 1 to 8, wherein, The heating electrode (51) of the heating layer (5) is nested and arranged on the isolation layer (4) through the heating electrode hole position (42) reserved on the isolation layer (4), so that one side of the heating electrode (51) is in an exposed environment, facilitating the connection of a heating voltage source. The heat resistance wire (53) is connected with the heating electrode (51) through the connecting wire (52).

10. The single-pass porous substrate according to any one of claims 1 to 9, wherein, The non-functional area (22) can receive the heat radiated by the heating electrode (51) to the non-functional area (22) through the trapezoidal slot portion on the isolation layer (4) and the heat conducted to the non-functional area (22) by the functional area (21) through the suspension (23), so that the second temperature required for the sensing reaction of the partial area on the non-functional area (22) is achieved.

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