Gas sensor and preparation method thereof

Abstract

The invention provides a gas sensor and a preparation method thereof, which are applied to the field of semiconductors. The gas sensor includes a transistor. The transistor comprises a channel layer, a barrier layer and a grid electrode which are sequentially arranged in a stacked mode. The barrier layer comprises a first groove structure, and the first groove structure is recessed in the direction from the barrier layer to the channel layer. At least part of the grid electrode is located in the first groove structure, and the material of the grid electrode comprises a gas sensitive material. The part of the barrier layer of the transistor of the gas sensor is thinned, so that the grid electrode is closer to two-dimensional electron gas between the barrier layer and the channel layer. Therefore, the charge change of the gas sensitive material of the grid affects the sensitivity of the change of the two-dimensional electron gas, so that the gas detection concentration range, the sensitivity and the response time of the whole gas sensor are improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the semiconductor field, and in particular, to a gas sensor and a method for preparing the gas sensor. Background Art

[0002] A gas sensor is a converter that converts the volume fraction of a certain gas into a corresponding electrical signal. Semiconductor gas sensors are the most common gas sensors that use semiconductor gas sensors as sensitive elements. Among them, the working principle of traditional semiconductor gas sensors is to use the oxidation-reduction reaction of gas on the surface of the semiconductor, which ultimately causes the resistance value of the sensitive element to change. Although this type of resistive gas sensor has high sensitivity, it does not have the ability to amplify signals, and its stability and accuracy are often affected by weak output signals. Field effect transistor (FET) gas sensors have signal amplification capabilities and can achieve high integration and miniaturization, so they have attracted much attention in the industry.

[0003] Gallium nitride (GaN) is a wide bandgap semiconductor with ultra-high stability in corrosive and high-temperature environments. Therefore, FET gas sensors using GaN as a substrate can detect toxic and harmful gases in extremely harsh environments such as high temperature and high corrosion. Specifically, GaN and gallium nitride compound AlGaN can form a heterojunction to form a high electron mobility transistor (HEMT). In the HEMT structure, there is a two-dimensional electron gas in the heterojunction. When a gas sensor including HEMT detects gas, gas molecules or atoms react with the gas-sensitive material of the HEMT gate, causing changes in the surface charge of the gas-sensitive material. The change in the surface charge of the gas-sensitive material directly affects the change in the surface density of the two-dimensional electron gas in the transistor heterojunction, and ultimately affects the output electrical properties of the transistor. In this way, by analyzing the output electrical properties of the transistor, the type and concentration of the gas molecules or atoms can be determined.

[0004] In order to improve the sensitivity, responsiveness and detection range of gas sensors, it is necessary to improve the sensitivity of changes in the two-dimensional electron gas in the transistor. Currently, the industry usually improves the structure of gas-sensitive materials to improve the ability of the gate to adsorb gas molecules or atoms, so that the gas molecules or atoms react more fully with the gas-sensitive materials, thereby better affecting the changes in the surface density of the two-dimensional electron gas. However, the process for preparing gas-sensitive materials is complicated, the preparation time is long and it is not suitable for mass production. Therefore, how to more efficiently and conveniently prepare gas sensors with a wider gas detection concentration range, higher sensitivity and faster response time is a problem that needs to be solved urgently. Summary of the invention

[0005] The embodiments of the present application provide a gas sensor and a method for preparing the gas sensor. The thickness of the barrier layer is thinned by locally etching the transistor in the gas sensor. In this way, the gate disposed on the thinned region of the barrier layer is closer to the two-dimensional electron gas in the heterojunction, thereby improving the sensitivity of the change of the two-dimensional electron gas in the transistor, so as to obtain a gas sensor with a wider gas detection concentration range, higher sensitivity, and faster response time.

[0006] In a first aspect, an embodiment of the present application provides a gas sensor, the gas sensor comprising:

[0007] The gas sensor includes a transistor, the structure of which includes a channel layer, a barrier layer and a gate which are stacked in sequence from bottom to top. The channel layer and the barrier layer are two different semiconductor materials, which contact each other to form a heterojunction. A two-dimensional electron gas exists in the heterojunction. The barrier layer includes a first groove structure, which is recessed in the direction from the barrier layer to the channel layer. The first groove structure is obtained by thinning the barrier layer. The gate is partially or completely located in the first groove structure, and the material of the gate includes a gas-sensitive material.

[0008] Specifically, when the gas sensor detects gas, the gas reacts with the gas-sensitive material of the gate, causing the charge on the surface of the gas-sensitive material to change. Next, the charge change will affect the surface density of the two-dimensional electron gas, and then the change in the surface density of the two-dimensional electron gas will be reflected in the output electrical properties of the transistor. In this way, the type and concentration of the detected gas can be inferred from the output electrical properties of the transistor and the type of gas-sensitive material. Local etching of the barrier layer can bring the gate (gas-sensitive material) closer to the two-dimensional electron gas. In this way, the charge change on the surface of the gas-sensitive material can better affect the change of the two-dimensional electron gas. The enhanced sensitivity of the change of the two-dimensional electron gas can obtain better transistor output characteristics, thereby improving the performance of the gas sensor.

[0009] In an optional embodiment, when the barrier layer is thinned, it can be partially thinned or completely removed. That is, the first groove structure in the barrier layer, along the direction from the barrier layer to the channel layer, can have a depth less than the thickness of the barrier layer or equal to the thickness of the barrier layer. Taking the direction from the barrier layer to the channel layer as the longitudinal direction, when the depth of the first groove structure is less than the thickness of the barrier layer, the gate located in the first groove structure will be closer to the two-dimensional electron gas in the longitudinal direction, and when the depth of the first groove structure is equal to the thickness of the barrier layer, the gate located in the first groove structure will be closer to the two-dimensional electron gas in the transverse direction, wherein the transverse direction is perpendicular to the longitudinal direction. The closer the gas-sensitive material of the gate is to the two-dimensional electron gas, the higher the sensitivity to the change of the two-dimensional electron gas in the transistor, so better transistor output characteristics can be obtained. In this way, even if the concentration of the gas to be detected is low, it can be reflected in the output characteristics of the transistor faster and more sensitively. Therefore, the gas sensor has a wider gas detection concentration range, higher sensitivity, and faster response time.

[0010] In an optional embodiment, when the barrier layer is thinned, the channel layer may also be slightly thinned. In this way, there is a first trench structure penetrating the barrier layer in the barrier layer of the transistor, and there is also a second trench structure in the channel layer. The first trench structure and the second trench structure are arranged opposite to each other, and the depth of the second trench structure in the channel layer in the direction from the barrier layer to the channel layer is less than the thickness of the channel layer.

[0011] In an optional embodiment, when the channel layer has a second trench structure, part of the gate structure will also be arranged in the second trench structure. In this way, the gate is laterally closer to the two-dimensional electron gas outside the second trench, thereby improving the sensitivity of the change of the two-dimensional electron gas to obtain better transistor output characteristics. In this way, even if the concentration of the gas to be detected is low, it can be reflected in the output characteristics of the transistor more quickly and sensitively. Therefore, the gas sensor has a wider gas detection concentration range, higher sensitivity, and faster response time.

[0012] In an optional embodiment, when only the barrier layer is thinned, the bottom of the first groove structure in the barrier layer may be a planar structure or may include at least one protruding structure. For example, a honeycomb columnar protrusion or a sawtooth protrusion may be provided at the bottom of the first groove structure. In this way, when the surface of the first groove structure is covered with a gas-sensitive material to form a gate, the presence of the protruding structure may increase the area of ​​the gas-sensitive material. In this way, the detected gas and the gas-sensitive material may react more fully, thereby expanding the gas detection concentration range of the gas sensor.

[0013] In an optional embodiment, when the channel layer is also thinned, the first trench structure of the barrier layer has no bottom, while the second trench structure of the channel layer has a bottom. The bottom of the second trench structure may also be a planar structure or include a protruding structure.

[0014] In a second aspect, an embodiment of the present application provides a method for preparing a gas sensor, the method comprising:

[0015] First, a channel layer and a barrier film layer are formed on the substrate structure from bottom to top. Then, the surface of the barrier film layer is partitioned, and a first groove structure is formed in the area where the gate is to be prepared to obtain the barrier layer. Specifically, the first groove structure is recessed along the direction from the barrier layer to the channel layer. Next, a gate is formed on the side of the barrier layer away from the channel layer, so that all or part of the gate falls within the first groove structure. At the same time, the material used to prepare the gate includes a gas-sensitive material.

[0016] The gas sensor made by this preparation method forms a groove structure in the area where the gate is to be set on the surface of the barrier film layer to reduce the thickness of the barrier layer in the area. In this way, the gate that falls entirely or partially in the first groove structure will be closer to the two-dimensional electron gas in the heterojunction. In this way, the charge change on the surface of the gas-sensitive material can better affect the change of the two-dimensional electron gas to enhance the sensitivity of the change of the two-dimensional electron gas. In this way, even if the concentration of the gas to be detected is low, it can be reflected in the output characteristics of the transistor more quickly and sensitively. Therefore, the prepared gas sensor has a wider gas detection concentration range, higher sensitivity, and faster response time.

[0017] In an optional embodiment, the barrier layer can be formed by etching the barrier film layer. Specifically, a protective layer can be formed on the barrier film layer, and the protective layer can be a photoresist or a hard mask. Then, the barrier film layer is etched under the protection of the protective layer to form a first trench structure to obtain the final barrier layer.

[0018] In an optional embodiment, when etching the barrier film layer, the barrier film layer can be partially etched or completely etched along the direction from the barrier layer to the channel layer, that is, the depth of the etched portion can be less than the thickness of the barrier film layer or equal to the thickness of the barrier film layer. Taking the direction from the barrier layer to the channel layer as the longitudinal direction, when the depth of the first trench structure of the barrier layer is less than the thickness of the barrier layer, the gate located in the first trench structure will be closer to the two-dimensional electron gas in the longitudinal direction, and when the depth of the first trench structure is equal to the thickness of the barrier layer, the gate located in the first trench structure will be closer to the two-dimensional electron gas in the transverse direction, wherein the transverse direction is perpendicular to the longitudinal direction. The closer the gas-sensitive material of the gate is to the two-dimensional electron gas, the higher the sensitivity of the change of the two-dimensional electron gas in the transistor, so that better transistor output characteristics can be obtained. In this way, even if the concentration of the gas to be detected is low, it can be reflected in the output characteristics of the transistor faster and more sensitively. Therefore, the gas sensor has a wider gas detection concentration range, higher sensitivity, and faster response time.

[0019] In an optional embodiment, under the protection of the protective layer, over-etching may occur during the etching of the barrier film layer, that is, part of the channel layer is also etched. At this time, the channel layer will form a second groove structure, which is directly opposite to the first groove structure of the barrier layer, and the depth of the second groove structure is smaller than the thickness of the channel layer.

[0020] In an optional embodiment, an etching pattern can be formed using photolithography technology, and then etching is performed based on the etching pattern. Specifically, after the protective layer is exposed and developed, a hollow portion will be formed on the protective layer. The pattern of the hollow portion is the same as the pattern of the first groove structure to be formed. Then, the barrier film layer is etched under the protection of the protective layer, so that the barrier film layer in the hollow portion area will be etched, and the barrier film layer in other areas will be retained. For a transistor structure, if the number of hollow portions of the protective layer is one, the bottom of the formed groove structure will be a planar structure. When the number of hollow portions of the protective layer is multiple and the hollow portions are spaced apart, the bottom of the formed groove structure will include a protruding structure.

[0021] In an optional embodiment, after the groove structure is set, a gate film layer needs to be deposited on the side of the barrier layer away from the channel layer, and the material of the gate film layer is a gas-sensitive material. This preparation method is simpler, controllable and time-saving. Next, the gate film layer needs to be bombarded with a preset plasma to pre-treat it, which can increase the adsorption sites of reactive ions on the surface of the gas-sensitive material, so that the reaction between the gas-sensitive material and the detection gas is more sufficient, further expanding the gas detection concentration range of the gas sensor.

[0022] In a third aspect, an embodiment of the present application provides a chip, which includes any one of the gas sensors provided in the first aspect above.

[0023] In a fourth aspect, an embodiment of the present application provides an electronic device, the electronic device comprising a chip and a circuit board as provided in the third aspect above, wherein the chip is arranged on the circuit board.

[0024] In an embodiment of the present application, the barrier layer of the transistor of the gas sensor is locally thinned to form a first trench structure. Then part or all of the gate is arranged in the first trench structure, and the material of the gate includes a gas-sensitive material. In this way, the gate will be closer to the two-dimensional electron gas in the heterojunction. When the gas sensor is detecting gas, the charge change on the surface of the gas-sensitive material can better affect the change of the two-dimensional electron gas, and the sensitivity of the change of the two-dimensional electron gas will be greatly enhanced. Since the change of the surface density of the two-dimensional electron gas will be reflected in the output electrical properties of the transistor, the enhancement of the sensitivity of the change of the two-dimensional electron gas will obtain better transistor output characteristics. In this way, even if the concentration of the gas to be detected is low, it can be reflected in the output characteristics of the transistor faster and more sensitively. Therefore, the gas sensor has a wider gas detection concentration range, higher sensitivity, and faster response time. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure of a GaN-based HEMT gas sensor shown in an embodiment of the present application;

[0026] Figure 2A A schematic structural diagram of a new GaN-based HEMT gas sensor provided in an embodiment of the present application;

[0027] Figure 2B A schematic structural diagram of a new GaN-based HEMT gas sensor provided in an embodiment of the present application;

[0028] Figure 2C A schematic structural diagram of a new GaN-based HEMT gas sensor provided in an embodiment of the present application;

[0029] Figure 3A A schematic structural diagram of a new GaN-based HEMT gas sensor provided in an embodiment of the present application;

[0030] Figure 3B A schematic structural diagram of a new GaN-based HEMT gas sensor provided in an embodiment of the present application;

[0031] Figure 4A A schematic structural diagram of a new GaN-based HEMT gas sensor provided in an embodiment of the present application;

[0032] Figure 4BA schematic structural diagram of a new GaN-based HEMT gas sensor provided in an embodiment of the present application;

[0033] Figure 4C A schematic structural diagram of a new GaN-based HEMT gas sensor provided in an embodiment of the present application;

[0034] Figure 5 A schematic structural diagram of a new GaN-based HEMT gas sensor provided in an embodiment of the present application;

[0035] Figure 6 A schematic diagram of a process for preparing a gas sensor provided in an embodiment of the present application;

[0036] Fig. 7A A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0037] Figure 7B A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0038] Figure 7C A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0039] Fig.7D A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0040] Fig. 7E A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0041] Figure 7F A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0042] Fig. 8A A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0043] Figure 8B A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0044] Fig. 9A A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0045] Fig. 9B A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0046] Fig. 9C A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0047] Fig. 10A A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0048] Fig. 10B A schematic diagram of a gas sensor manufacturing process provided in an embodiment of the present application;

[0049] Fig. 10C A schematic diagram of the preparation process of a gas sensor provided in an embodiment of the present application. DETAILED DESCRIPTION

[0050] The embodiment of the present application provides a gas sensor and a method for preparing the gas sensor. The thickness of the barrier layer is thinned by locally etching the transistor in the gas sensor. In this way, the gate disposed on the thinned region of the barrier layer is closer to the two-dimensional electron gas between the barrier layer and the channel layer, thereby improving the sensitivity of the change of the two-dimensional electron gas in the transistor, so as to obtain a gas sensor with a wider gas detection concentration range, higher sensitivity, and faster response time.

[0051] In the description of this application, unless otherwise specified, " / " indicates that the objects associated with each other are in an "or" relationship, for example, A / B can represent A or B; "and / or" in this application is merely a description of the association relationship between associated objects, indicating that three relationships may exist, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural.

[0052] In the description of this application, unless otherwise specified, "plurality" means two or more than two. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0053] In addition, in order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, words such as "first" and "second" are used to distinguish the same items or similar items with substantially the same functions and effects. Those skilled in the art can understand that words such as "first" and "second" do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit the difference.

[0054] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way for easy understanding.

[0055] It is understood that the "embodiment" mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, the various embodiments in the entire specification do not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It is understood that in various embodiments of the present application, the size of the sequence number of each process does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0056] It can be understood that some optional features in the embodiments of the present application may be implemented independently in certain scenarios without relying on other features, such as the solution on which they are currently based, to solve corresponding technical problems and achieve corresponding effects, or may be combined with other features according to needs in certain scenarios. Accordingly, the devices provided in the embodiments of the present application may also realize these features or functions accordingly, which will not be elaborated here.

[0057] In this application, unless otherwise specified, the same or similar parts between the various embodiments can refer to each other. In this application, if there is no special description or logical conflict between the various embodiments, the terms and / or descriptions between different embodiments are consistent and can be referenced to each other, and different embodiments can be combined to form new embodiments according to their inherent logical relationships. The following implementation methods of this application do not constitute a limitation on the scope of protection of this application.

[0058] In order to facilitate understanding of the technical solutions of the embodiments of the present application, a brief introduction to the relevant technologies of the embodiments of the present application is given below:

[0059] Semiconductor gas sensors are gas sensors that use semiconductor gas sensors as sensitive elements. As the most common gas sensor currently, they are widely used in various fields. For example, semiconductor gas sensors can be used in combustible gas leak detection devices in homes or factories to detect methane, liquefied gas, hydrogen, etc.

[0060] According to the physical properties of semiconductor changes, semiconductor gas sensors can be divided into resistance-type gas sensors and non-resistance-type gas sensors. Traditional resistance-type gas sensors use the change in the resistance of semiconductors when they come into contact with gas to determine the composition and concentration of the gas. That is, the gas undergoes an oxidation-reduction reaction on the surface of the semiconductor, causing the resistance value of the component to change. Specifically, the semiconductor device is heated to a stable state. When the gas contacts the semiconductor surface and is adsorbed, the adsorbed gas molecules first diffuse freely on the semiconductor surface. Then, after losing the kinetic energy, a part of it is evaporated, and the other part is thermally decomposed and adsorbed on the semiconductor surface. At this time, if the work function of the semiconductor is less than the affinity of the adsorbed molecule (such as oxidizing gases such as oxygen), the adsorbed molecule will take electrons from the semiconductor device and become negative ions adsorbed on the semiconductor surface. At this time, the semiconductor surface will present a charge layer. If the work function of the semiconductor is greater than the dissociation energy of the adsorbed molecule (such as reducing gases such as hydrogen and carbon monoxide), the adsorbed molecule will release electrons to the semiconductor device, forming positive ion adsorption. At this time, if negative ions are adsorbed on n-type semiconductors or positive ions are adsorbed on p-type semiconductors, the semiconductor carriers will decrease and the resistance of the semiconductor will increase. When positive ions are adsorbed onto n-type semiconductors or negative ions are adsorbed onto p-type semiconductors, the number of carriers in the semiconductor increases and its resistance decreases. In this way, by detecting the resistance of the semiconductor, the composition and concentration of the gas in contact with it can be determined.

[0061] The above-mentioned resistance type gas sensor is low-cost, simple to manufacture, and has high sensitivity and fast response speed. However, it does not have the ability to amplify signals. The input signal is weak, and its stability and accuracy are often affected by the weak output signal. Moreover, the resistance type gas sensor must work in a high temperature environment and has poor selectivity for gas. Therefore, non-resistance type semiconductor gas sensors are becoming more and more popular in the industry.

[0062] Non-resistance semiconductor gas sensors are gas sensors made by utilizing the changes in the capacitance-voltage characteristics of metal-oxide-semiconductor MOS diodes or the changes in the threshold voltage of MOS field-effect transistors. The manufacturing process of this type of sensor is mature, which facilitates high integration and miniaturization of devices, and has stable performance and low cost. At the same time, if specific gas-sensitive materials are used, the sensor can be made particularly sensitive to certain gases. Field effect transistor (FET) gas sensors are typical representatives of non-resistance semiconductor gas sensors.

[0063] Among them, the substrate material of FET gas sensors is usually silicon Si. Due to the narrow bandgap width of Si material, the operating temperature of FET gas sensors with Si as substrate is usually limited to below 200°C. In order to improve the selectivity, sensitivity and response / recovery time of gas detection of FET gas sensors, a higher operating temperature is usually required. Therefore, Si-FET gas sensors cannot meet the above requirements. GaN, as a wide bandgap semiconductor, is highly stable in corrosive and high temperature environments. With its own superior characteristics, gas sensors with GaN as substrate material are widely used in high temperature, high pressure, and high frequency applications, and can complete the detection of toxic and harmful gases in extremely harsh environments such as high temperature, high pressure, and high corrosion.

[0064] Figure 1 FIG. 1 is a schematic diagram of the structure of a GaN-based gas sensor shown in an embodiment of the present application. Figure 1 As shown, the gas sensor includes a transistor, and the transistor is a high electron mobility transistor (HEMT) composed of GaN and aluminum gallium nitride AlGaN, and specifically includes a source / drain 11, a gate 12, a buffer layer 13, a channel layer 14, and a barrier layer 15.

[0065] Among them, the barrier layer 15 and the channel layer 14 form a heterojunction. A heterojunction is a special PN junction formed by two semiconductors with similar crystal structures, similar atomic spacing and thermal expansion coefficients, and usually has excellent photoelectric properties that cannot be achieved by the PN junctions of the two semiconductors. Specifically, due to the low energy level between the two semiconductor layers, the electrons in the semiconductor are easily confined in the middle, and the middle layer is only a few dozen angstroms thick. In such a small space, the characteristics of the electrons will be affected by quantum effects and change. For example, the mobility of the electrons in the middle layer will increase. This is because, in general semiconductor materials, the free electrons therein are mainly formed by impurities, and the free electrons will be collided by impurities and their mobility will be reduced. However, in a heterojunction structure, impurities will be added to the interlayers on both sides, and the electrons contributed by the impurities will fall into the middle layer because of their lower energy. Therefore, in space, electrons and impurities are separated, so the movement of electrons will not be restricted by the collision of impurities, so their mobility is greatly increased. This HEMT structure formed by heterojunction will form a high electron concentration channel near the surface of the channel layer in contact with the barrier layer, which is very sensitive to adsorbed gas molecules or atoms. At the same time, because the electrons are confined in the middle, they cannot move freely along the direction of the interlayer. Therefore, the electrons only have two degrees of freedom, that is, a two-dimensional electron gas is formed. The surface density of the two-dimensional electron gas directly affects the output electrical properties of the HEMT.

[0066] Exemplarily, the material of the barrier layer 15 may be AlGaN or indium aluminum nitride InAlN, and the material of the channel layer 14 may be a GaN layer. Based on the above description, the working principle of the HEMT gas sensor is that the gas-sensitive material of the gate 12 reacts with the gas to be measured, thereby causing a charge change on the surface of the gas-sensitive material, and the charge change of the gate 12 causes the flow of carriers between the drain and the source, thereby affecting the surface density of the two-dimensional electron gas in the heterojunction structure. The surface density change of the two-dimensional electron gas will be reflected in the output electrical properties of the HEMT. Therefore, the type and concentration of the detected gas can be inferred from the output electrical properties of the HEMT gas sensor and the type of gas-sensitive material. In a specific example, if the gas to be measured is carbon monoxide CO, at this time, oxygen anions O2-, O2-, O- will be adsorbed on the surface of the gas-sensitive material. When the detection gas is introduced, the CO gas will react with the oxygen anions on the surface of the gas-sensitive material to release carbon dioxide gas, and at the same time release the surface electrons e- back to the gas-sensitive material. Next, the change in the surface charge of the gas-sensitive material directly affects the surface density of the two-dimensional electron gas generated by polarization in the heterojunction structure, which is then reflected in the electrical output properties of the HEMT.

[0067] It is understandable that the industry's common goal is to prepare gas sensors with a wider gas detection concentration range, higher sensitivity, and faster response time. To improve the performance of HEMT gas sensors, it is necessary to improve the sensitivity of changes in the surface density of the two-dimensional electron gas. In other words, even if the concentration of the measured gas is very low, it can cause rapid and sensitive changes in the two-dimensional electron gas, so that the measured gas can be detected in a timely, efficient and sensitive manner through the output electrical properties of the HEMT gas sensor.

[0068] At present, the industry usually improves the performance of HEMT gas sensors by improving gas-sensitive materials. Specifically, the surface area of ​​the gas-sensitive material is increased to increase the gas attachment sites, so that the measured gas and the gas-sensitive material react more fully, and the charge change on the surface of the gate gas-sensitive material is increased to increase the sensitivity of the change in the surface density of the two-dimensional electron gas, so as to achieve a wider detection limit of the HEMT gas sensor. For example, nanostructured gas-sensitive materials such as nanoporous Pt, nanocolumns, nanowires, and nanospherical metal oxides are usually used. However, the preparation process of nanostructured gas-sensitive materials is complicated, the process time is long, and it is not suitable for mass production. Therefore, how to more efficiently and conveniently prepare gas sensors with a wider gas detection concentration range, higher sensitivity, and faster response time is a problem that needs to be solved urgently.

[0069] Based on the above description of GaN-based HEMT gas sensors, Figure 2A A schematic diagram of the structure of a new GaN-based HEMT gas sensor provided in an embodiment of the present application. Figure 2AAs shown, the embodiment of the present application adopts a solution of locally thinning the barrier layer to improve the performance of the HEMT gas sensor.

[0070] Specifically, the HEMT gas sensor includes a source / drain 11, a gate 12, a buffer layer 13, a channel layer 14, and a barrier layer 15. The barrier layer 15 and the channel layer 14 form a heterojunction, and two-dimensional electron gas exists near the surface where the channel layer 14 contacts the barrier layer 15.

[0071] In the embodiment of the present application, a first groove structure 210 is formed on the barrier layer 15, and the first groove structure 210 is recessed toward the channel layer 14, and the gate 12 is completely or partially located in the first groove structure 210, and the material of the gate 12 includes a gas-sensitive material. Specifically, the barrier layer 15 is partially etched to reduce the thickness of the barrier layer 15, so that the gate 15 (gas-sensitive material) located in the first groove structure 210 is closer to the two-dimensional electron gas, so that the charge change on the surface of the gas-sensitive material can better affect the change of the two-dimensional electron gas, and the sensitivity of the change of the two-dimensional electron gas is enhanced. In this way, the HEMT gas sensor can capture the current response signal under the weak gas concentration change, even if the concentration of the measured gas is very low, it can be detected, and the gas detection concentration range of the HEMT gas sensor will be wider, the sensitivity will be higher, and the response time will be faster.

[0072] For example, when the barrier layer 15 is thinned, it can be partially thinned or completely removed. That is, the first trench structure 210 in the barrier layer 15, along the direction from the barrier layer 15 to the channel layer 14, can have a depth less than the thickness of the barrier layer 15 or equal to the thickness of the barrier layer 15. It is understandable that Figure 2A In the structure shown, the barrier layer 15 is only partially thinned, that is, the depth of the first trench structure 210 is less than the thickness of the barrier layer 15, and the first trench structure 210 does not penetrate the barrier layer 15. Figure 2B In the structure shown, the barrier layer 15 at the first trench structure 210 is completely removed, that is, the depth of the first trench structure 210 is just equal to the thickness of the barrier layer 15. The direction from the barrier layer to the channel layer is the longitudinal direction. Figure 2A When the depth of the first trench structure 210 is less than the thickness of the barrier layer 15, the gate 12 located in the first trench structure 210 will be closer to the two-dimensional electron gas in the vertical direction. Figure 2BWhen the depth of the first trench structure 210 shown is equal to the thickness of the barrier layer 15, the gate 12 located in the first trench structure 210 will be closer to the two-dimensional electron gas in the horizontal direction, where the horizontal direction is perpendicular to the vertical direction. The closer the gas-sensitive material of the gate 12 is to the two-dimensional electron gas, the higher the sensitivity to the change of the two-dimensional electron gas in the transistor, so that better transistor output characteristics can be obtained. In this way, even if the concentration of the gas to be detected is low, it can be reflected in the output characteristics of the transistor more quickly and sensitively. Therefore, the gas sensor has a wider gas detection concentration range, higher sensitivity, and faster response time.

[0073] For example, when the barrier layer 15 is thinned, the channel layer 14 may also be slightly thinned. Figure 2C As shown, after both the barrier layer 15 and the channel layer 14 are thinned, a first trench structure 210 penetrating the barrier layer 15 exists in the barrier layer 15 of the transistor, and a second trench structure 220 also exists in the channel layer 14. The first trench structure 210 in the barrier layer 15 and the second trench structure 220 in the channel layer 14 are arranged opposite to each other, and the depth of the second trench structure 220 in the direction from the barrier layer 15 to the channel layer 14 can be less than the thickness of the channel layer 14. It can be understood that if the first trench structure 210 is formed by etching, the second trench structure 220 is formed by over-etching the barrier layer 15. When the channel layer 14 also has a trench, part of the gate 12 also needs to be located in the second trench structure 220. In this way, the gate 12 is laterally closer to the two-dimensional electron gas outside the second trench structure 220, and the sensitivity of changes in the two-dimensional electron gas in the transistor becomes higher, so that better transistor output characteristics can be obtained. In this way, even if the concentration of the gas to be detected is low, it can be reflected in the output characteristics of the transistor more quickly and sensitively. Therefore, the gas sensor has a wider gas detection concentration range, higher sensitivity, and faster response time.

[0074] It can be understood that the gate 12 is disposed on the side of the barrier layer 15 away from the channel layer 14, and at least a portion of the gate 12 needs to fall into the first trench structure 210 or the second trench structure 220. Then, taking the structure in which the barrier layer 15 is only thinned as an example, Figure 2A As shown, the barrier layer 15 is partially thinned to form a first trench structure 210, and the first trench structure 210 does not penetrate the barrier layer 15, and the gate 12 is just embedded in the first trench structure 210, and its size is the same as that of the first trench structure 210. Figure 3A As shown, the barrier layer 15 is partially thinned to form a first trench structure 210, and the gate 12 is larger than the first trench structure 210. At this time, the gate 12 extends from the inside of the first trench structure 210 to the outside of the first trench structure 210, and a portion of the gate 12 is flat on the surface of the barrier layer 15 without a trench. Figure 3BAs shown, the barrier layer 15 is partially thinned to form a first trench structure 210, and the size of the gate 12 is smaller than the size of the first trench structure 210, and the gate 12 is completely within the first trench structure 210. It can be understood that the embodiment of the present application does not limit the size of the gate 12, and it only requires that at least a portion of the gate 12 is located within the trench structure.

[0075] The shape of the trench structure may also include various shapes. For example, taking the structure in which the barrier layer 15 is only thinned as an example, Figure 2A As shown, the bottom of the first trench structure 210 is a planar structure. Figure 4A As shown, the bottom of the first groove structure 210 includes a protruding structure 2101. For example, the protruding structure 2101 can be a triangular prism, a circular column or a square column, which is not specifically limited. Figure 5 As shown, the cross section of the first trench structure 210 can also be sawtooth-shaped, that is, the trench structure only needs to thin the thickness of the barrier layer below the gate, and the specific shape is not limited. If the depth of the first trench structure 210 is just equal to the thickness of the barrier layer 15, as shown in FIG. Figure 2B As shown, the first trench structure 210 may be a through cavity that penetrates the entire barrier layer 15. Figure 4B As shown, the first groove structure 210 may further include a protrusion structure 2101 inside.

[0076] When the channel layer 14 also has the second trench structure 220, the first trench structure 210 of the barrier layer is a through cavity, and the first trench structure 210 has no bottom. Figure 2C As shown, the bottom of the second trench structure 220 of the channel layer 14 may be a planar structure. Figure 4C As shown, the bottom of the second groove structure 220 may also have a protruding structure 2201. It is understandable that, whether the bottom of the first groove structure 210 has a protrusion or the second groove structure 220 has a protrusion, when the gas-sensitive material is covered to form a gate, the presence of the protruding structure can increase the area of ​​the gas-sensitive material. In this way, the detected gas and the gas-sensitive material can react more fully, thereby expanding the gas detection concentration range of the gas sensor. Exemplarily, the gas-sensitive material can adopt a gas-sensitive material with a structure such as nanoporous Pt, nanocolumns, nanowires, and nanospherical metal oxides to further increase the gas attachment site. A gas-sensitive material film can also be formed by deposition. Compared with the nanostructured gas-sensitive material prepared by methods such as hydrothermal synthesis, this material has the advantages of simple preparation method, controllable, time-saving, etc., and the cost is further reduced.

[0077] In the embodiment of the present application, either only the barrier layer 15 of the transistor has the first trench structure 210, and the first trench structure 210 is recessed in the direction from the barrier layer 15 to the channel layer 14. Since part or all of the gate 12 is disposed in the first trench structure 210, the gate 12 will be closer to the two-dimensional electron gas in the vertical direction. Alternatively, the transistor not only has the first trench structure 210 in the barrier layer 15, but also has a second trench structure 220 with a shallower depth in the channel layer 14. Since part of the gate 12 is also present in the second trench structure 220, at this time, in the horizontal direction, the gate 12 will be closer to the two-dimensional electron gas outside the second trench structure 220. Since the material of the gate 12 includes a gas-sensitive material, the charge change on the surface of the gas-sensitive material closer to the two-dimensional electron gas can better affect the change of the two-dimensional electron gas. In this way, the sensitivity of the change of the two-dimensional electron gas in the transistor will be greatly enhanced. The change of the surface density of the two-dimensional electron gas will be reflected in the output electrical properties of the transistor. Therefore, the enhancement of the sensitivity of the change of the two-dimensional electron gas will obtain better transistor output characteristics. In this way, even if the concentration of the gas to be detected is low, it can be reflected in the output characteristics of the transistor more quickly and sensitively. Therefore, the gas sensor has a wider gas detection concentration range, higher sensitivity, and faster response time.

[0078] Based on the HEMT gas sensor described in the above embodiment, the preparation process of the gas sensor is described in detail below: Figure 2A Take the gas sensor shown as an example, Figure 6 The following is a flow chart of a method for preparing a gas sensor provided in an embodiment of the present application. Figure 6 As shown, the preparation process includes the following steps:

[0079] 601. A channel layer 14 and a barrier film layer 151 are sequentially formed on a substrate structure.

[0080] First, a buffer layer 13, a channel layer 14 and a barrier film layer 151 need to be formed on the substrate in sequence. Fig. 7A As shown, from bottom to top, the substrate, buffer layer 13, channel layer 14 and barrier film layer 151 may be sequentially provided. Among them, the channel layer 14 and the barrier film layer 151 form a heterojunction, and a two-dimensional electron gas exists in the heterojunction. Exemplarily, the barrier film layer 151 may be an AlGaN layer, or may be replaced by an indium aluminum nitride InAlN layer, and the channel layer 14 may be a GaN layer. Of course, the materials of the barrier film layer 151 and the channel layer 14 may also include other materials, which are not limited in the embodiments of the present application.

[0081] Then the surface of the entire structure is cleaned, for example, it can be firstly cleaned with acetone ultrasound for several minutes, then cleaned with isopropyl alcohol for several minutes, finally rinsed with deionized water for several minutes, and then blown dry with nitrogen. This step is to remove organic matter, particles, impurities, etc. on the surface of the substrate structure.

[0082] 602, such as Figure 7B As shown, source / drain electrodes 11 are formed on the barrier film layer 151 .

[0083] Exemplarily, the preparation process of the source / drain 11 can be: first, evenly apply photoresist on the barrier film layer 151, take the photoresist as a positive photoresist as an example, use ultraviolet rays to irradiate its surface through a mask, cause the photoresist in the exposed area to undergo a chemical reaction (exposure), and then dissolve and remove the exposed part of the photoresist through a developing technology, leaving the unexposed part of the photoresist, so as to define the pattern of the source / drain 11 on the barrier film layer 151, and deposit metal electrodes respectively. Then, under the protection of the photoresist, remove the area of ​​the photoresist. Then, through an annealing process, each metal electrode is formed into an ohmic contact with the barrier film layer 151, and finally the source / drain 11 is formed.

[0084] Of course, other processes can also be used to prepare the source and drain, and the present embodiment does not limit the preparation method of the source and drain. At the same time, the present embodiment does not limit the material of the source and drain, as long as the source and drain include conductive materials.

[0085] 603 . Form a first trench structure 210 in the barrier film layer 151 to obtain a barrier layer 15 .

[0086] Exemplarily, the first trench structure 210 can be formed in the barrier film layer 151 by photolithography and etching. The first trench structure 210 needs to be recessed in the direction from the barrier layer to the channel layer. The etching process is described in detail below:

[0087] First, a protective layer needs to be deposited on the barrier film layer 151 so that the barrier film layer 151 is etched under the protection of the protective layer. The protective layer can be a hard mask, a photoresist, or a hard mask plus a photoresist. The structure of a hard mask plus a photoresist is used as an example for explanation.

[0088] like Figure 7C As shown, a hard mask 16 is formed on a side of the barrier film layer 151 away from the channel layer 14 , and the material of the hard mask 16 may include a silicon nitride SiNx dielectric layer.

[0089] Then, if Fig.7DAs shown, it is necessary to evenly apply photoresist 17 on the surface of the hard mask 16, and then use photolithography technology to form a first hollow portion 1701 on the photoresist 17. Specifically, taking the photoresist 17 as a positive photoresist as an example, ultraviolet rays are irradiated on the surface of the photoresist 17 through the mask, causing the photoresist 17 in the exposed area to undergo a chemical reaction (exposure), and then the photoresist in the exposed area is dissolved and removed by the development technology, and the first hollow portion 1701 appears on the photoresist 17.

[0090] Then, if Fig. 7E As shown, under the protection of the photoresist 17 , the hard mask 16 is etched to form a second hollow portion 1602 in the hard mask 16 .

[0091] Then, if Figure 7F As shown, the remaining photoresist on the hard mask 16 is removed, leaving the hard mask including the second hollow portion 1602. The pattern of the second hollow portion 1602 can be in various shapes.

[0092] It can be understood that the patterns of the first hollow portion 1701 and the second hollow portion 1602 are consistent, and the pattern of the second hollow portion 1602 is also consistent with the pattern of the first trench structure 210 to be formed. Figure 7F There is only one second hollow portion 1602 on the hard mask 16. Fig. 8A As shown in FIG. 1 , after the photoresist 17 is exposed and developed, a plurality of first hollow portions 1701 appear on the photoresist 17. Then, Figure 8B As shown, after the hard mask 16 is etched with the photoresist 17 shown in FIG8A , a plurality of second hollow portions 1602 are formed on the hard mask 16 .

[0093] Next, under the protection of the hard mask 16 having the second hollow portion 1602, the barrier film layer 151 is etched to obtain the barrier layer 15. When etching the barrier film layer 151, the etching depth may be less than the thickness of the barrier film layer 151, or may be equal to the thickness of the barrier film layer 151, or may be over-etched, that is, a portion of the channel layer 14 is etched away. After the etching is completed, the hard mask 16 needs to be removed.

[0094] First Figure 7F The structure shown is used as an example to illustrate. Figure 7F There is only one second hollow portion 1602 on the hard mask 16 shown in FIG. Figure 7F After the barrier film layer 151 is etched, the bottom of the obtained first trench structure 210 is a planar structure.

[0095] like Fig. 9A As shown, the etching depth of the barrier film layer 151 is less than the thickness of the barrier film layer 151. Specifically, Figure 7FAfter the barrier film layer 151 is etched, a barrier layer 15 including a first trench structure 210 is formed. The depth of the first trench structure 210 in the direction from the barrier layer 15 to the channel layer 14 is less than the thickness of the barrier layer 15 .

[0096] Another example Fig. 9B As shown, the etching depth of the barrier film layer 151 is equal to the thickness of the barrier film layer 151. Specifically, Figure 7F After the barrier film layer 151 is etched, a barrier layer 15 including a first trench structure 210 is formed. The first trench structure 210 has a depth equal to the thickness of the barrier layer 15 in a direction from the barrier layer 15 to the channel layer 14 .

[0097] Another example Fig. 9C As shown, the etching depth of the barrier film layer 151 is greater than the thickness of the barrier film layer 151 (over-etching), and part of the channel layer 14 will also be etched. Specifically, Figure 7F After the barrier film layer 151 is etched, a barrier layer 15 including a first trench structure 210 is formed, and a second trench structure 220 also exists on the channel layer 14. The first trench structure 210 and the second trench structure 220 are arranged opposite to each other, and the depth of the second trench structure 220 needs to be less than the thickness of the channel layer 14.

[0098] Then with Figure 8B Taking the structure shown as an example, due to Figure 8B There are a plurality of second hollow portions 1602 on the hard mask 16 shown in FIG. Figure 8B After the barrier film layer 151 is etched, the bottom of the obtained first trench structure 210 will include a protruding structure.

[0099] like Fig. 10A As shown, the etching depth of the barrier film layer 151 is less than the thickness of the barrier film layer 151. Specifically, Figure 8B After the barrier film layer 151 is etched, a barrier layer 15 including a first trench structure 210 is formed, and the depth of the first trench structure 210 in the direction from the barrier layer 15 to the channel layer 14 is less than the thickness of the barrier layer 15. In addition, the bottom of the first trench structure 210 includes a protrusion structure 2101.

[0100] Another example Fig. 10B As shown, the etching depth of the barrier film layer 151 is equal to the thickness of the barrier film layer 151. Specifically, Figure 8B After the barrier film layer 151 is etched, a barrier layer 15 including a first trench structure 210 is formed, and the first trench structure 210 has a depth equal to the thickness of the barrier layer 15 in the direction from the barrier layer 15 to the channel layer 14. In addition, the bottom of the first trench structure 210 includes a protrusion structure 2101.

[0101] Another example Fig. 10C As shown, the etching depth of the barrier film layer 151 is greater than the thickness of the barrier film layer 151 (over-etching), and part of the channel layer 14 will also be etched. Specifically, Figure 8B After the barrier film layer 151 is etched, a barrier layer 15 including a first trench structure 210 is formed, and a second trench structure 220 also exists on the channel layer 14. The first trench structure 210 and the second trench structure 220 are arranged opposite to each other, and the depth of the second trench structure 220 needs to be less than the thickness of the channel layer 14. In addition, the bottom of the second trench structure 220 includes a protruding structure 2201.

[0102] 604 . Form a gate 12 on a side of the barrier layer 15 facing away from the channel layer 14 .

[0103] At least part of the gate 12 is located in the trench structure, and the material of the gate 12 includes a gas-sensitive material. Exemplarily, it is necessary to deposit a gate film layer, because the preparation of the gas-sensitive thin film material is simpler, controllable and time-saving. Then, it is necessary to define the pattern of the gate 12 on the protective layer using a photolithography process, and then etch the gate film layer under the protection of the protective layer to finally form the gate 12.

[0104] Exemplarily, after forming the gate film layer and before photolithography, the gate film layer can be bombarded with a preset plasma for pretreatment. Exemplarily, a preset plasma that reacts with the detection gas can be used to bombard the gas-sensitive material, which can increase the adsorption sites of reactive ions on the surface of the gas-sensitive material, making the reaction between the gas-sensitive material and the detection gas more complete, and further expanding the gas detection concentration range of the gas sensor. For example, in the scenario of detecting carbon monoxide CO, oxygen negative ion O2 plasma can be used to bombard the gas-sensitive film material for pretreatment to increase the oxygen negative ion adsorption sites on the surface of the gas-sensitive material.

[0105] like Figure 2A As shown, Fig. 9A After the gate 12 is formed in the structure shown, the gate 12 is located in the first trench structure 210 of the barrier layer 15. Taking the direction from the barrier layer 15 to the channel layer 14 as the longitudinal direction, when the depth of the first trench structure 210 is less than the thickness of the barrier layer 15, the gate 12 located in the first trench structure 210 will be closer to the two-dimensional electron gas in the longitudinal direction.

[0106] Another example Figure 2B As shown, Fig. 9A After the gate 12 is formed in the structure shown, the gate 12 is located in the first trench structure 210 of the barrier layer 15, wherein the depth of the first trench structure 210 is equal to the thickness of the barrier layer 15, and the gate 12 located in the first trench structure 210 will be closer to the two-dimensional electron gas in the lateral direction, wherein the lateral direction is perpendicular to the longitudinal direction.

[0107] Another example Figure 2C As shown, Fig. 9A After the gate 12 is formed in the structure shown, a portion of the gate 12 is located in the first trench structure 210 of the barrier layer 15, and another portion is located in the second trench structure 220. At this time, the gate 12 will be closer to the two-dimensional electron gas in the lateral direction.

[0108] The closer the gas-sensitive material of the gate 12 is to the two-dimensional electron gas, the higher the sensitivity of the change of the two-dimensional electron gas in the transistor, so that better transistor output characteristics can be obtained. In this way, even if the concentration of the gas to be detected is low, it can be reflected in the output characteristics of the transistor more quickly and sensitively. In this way, the gas sensor will have a wider gas detection concentration range, higher sensitivity, and faster response time.

[0109] Similarly, if Figure 4A As shown, Fig. 10A After the gate 12 is formed in the structure shown, the gate 12 is located in the first trench structure 210 of the barrier layer 15. Fig. 10B As shown, Fig. 9A After the gate 12 is formed in the structure shown, the gate 12 is located in the first trench structure 210 of the barrier layer 15. Figure 4C As shown, Fig. 10A After the gate 12 is formed in the structure shown, a portion of the gate 12 is located in the first trench structure 210 of the barrier layer 15, and another portion is located in the second trench structure 220. It can be understood that the structures shown in 4A, 4B, and 4C have a larger surface area of ​​the gas-sensitive thin film material than the structures shown in 2A, 2B, and 2C, so that the detected gas and the gas-sensitive material react more fully, further expanding the gas detection concentration range of the gas sensor.

[0110] The gas sensor made by the above preparation method reduces the thickness of the barrier film layer 151 in the area where the gate 12 is to be set by forming a groove structure in the barrier film layer 151. In this way, the gate 12 that falls entirely or partially in the groove structure will be closer to the two-dimensional electron gas in the heterojunction. In this way, the charge change on the surface of the gas-sensitive material can better affect the change of the two-dimensional electron gas, so as to enhance the sensitivity of the change of the two-dimensional electron gas. In this way, even if the concentration of the gas to be detected is low, it can be reflected in the output characteristics of the transistor more quickly and sensitively. Therefore, the prepared gas sensor has a wider gas detection concentration range, higher sensitivity, and faster response time.

[0111] An embodiment of the present application also provides a chip, which includes any one of the gas sensors in the above embodiments.

[0112] The embodiment of the present application also provides an electronic device, which includes the chip and the circuit board provided in the above embodiment, wherein the chip is arranged on the circuit board.

[0113] It is understandable that in the embodiments of the present application, the execution subject may execute some or all of the steps in the embodiments of the present application, and these steps or operations are only examples. The embodiments of the present application may also execute other operations or variations of various operations. In addition, the various steps may be executed in different orders presented in the embodiments of the present application, and it is possible that not all operations in the embodiments of the present application need to be executed.

[0114] It should be noted that the message names between the devices or the names of the parameters in the messages in the following embodiments of the present application are only examples, and other names may be used in the specific implementation, and the embodiments of the present application do not specifically limit this.

[0115] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using a software program, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loading and executing computer program instructions on a computer, all or part of the processes (or functions) described in the embodiments of the present application are implemented. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or may contain one or more servers, data centers and other data storage devices that can be integrated with the medium. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (eg, a solid state disk (SSD)), etc. In the embodiment of the present application, the computer may include the aforementioned device.

[0116] Although the present application is described herein in conjunction with various embodiments, in the process of implementing the claimed application, those skilled in the art may understand and implement other variations of the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "one" or "an" does not exclude multiple situations. A single processor or other unit may implement several functions listed in a claim. Certain measures are recorded in different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

Claims

1. A gas sensor, characterized in that: The gas sensor includes a transistor, wherein the transistor includes a channel layer, a barrier layer, and a gate which are stacked in sequence; The barrier layer includes a first trench structure; the first trench structure is recessed along a direction from the barrier layer to the channel layer; at least a portion of the gate is located in the first trench structure, and a material of the gate includes a gas-sensitive material.

2. The gas sensor according to claim 1, characterized in that Along the direction from the barrier layer to the channel layer, the depth of the first trench structure is less than or equal to the thickness of the barrier layer.

3. The gas sensor according to claim 2, characterized in that: In a case where the depth of the first trench structure is equal to the thickness of the barrier layer, the channel layer includes a second trench structure; The second trench structure is arranged opposite to the first trench structure, and the depth of the second trench structure is less than the thickness of the channel layer.

4. The gas sensor according to claim 3, characterized in that: The gate is also located in the second trench structure.

5. The gas sensor according to claim 2, characterized in that: The bottom of the first trench structure is a planar structure; or, The bottom of the first trench structure includes at least one protruding structure.

6. The gas sensor according to claim 3 or 4, characterized in that: The bottom of the second groove structure is a planar structure, or the bottom of the second groove structure includes at least one protruding structure.

7. A method for preparing a gas sensor, characterized in that: The method comprises: forming a channel layer and a barrier film layer in sequence; forming a first trench structure in the barrier film layer to obtain a barrier layer; the first trench structure is recessed along a direction from the barrier layer to the channel layer; A gate is formed on a side of the barrier layer facing away from the channel layer; wherein at least a portion of the gate is located in the first trench structure, and a material of the gate includes a gas-sensitive material.

8. The preparation method according to claim 7, characterized in that: The step of forming a first trench structure in the barrier film layer to obtain a barrier layer comprises: forming a protective layer on the barrier layer; Under the protection of the protection layer, the barrier film layer is etched to obtain the barrier layer including the first trench structure.

9. The preparation method according to claim 8, characterized in that: Along the direction from the barrier layer to the channel layer, the depth of the etched portion of the barrier film layer is less than or equal to the thickness of the barrier film layer.

10. The preparation method according to claim 8, characterized in that: In the process of etching the barrier film layer under the protection of the protective layer, the preparation method further comprises: The channel layer is partially etched to form a second trench structure; wherein the second trench structure is arranged opposite to the first trench structure, and the depth of the second trench structure is less than the thickness of the channel layer.

11. The preparation method according to any one of claims 8 to 10, characterized in that: The protective layer includes a hollow portion, and a pattern of the hollow portion is the same as a pattern of the first groove structure to be formed; The number of the hollow parts is one; or, the number of the hollow parts is multiple, and the multiple hollow parts are arranged at intervals.

12. The preparation method according to any one of claims 7 to 11, characterized in that: The forming of a gate on a side of the barrier layer away from the channel layer comprises: Depositing a gate film layer on a side of the barrier layer away from the channel layer; The gate film layer is bombarded and pre-treated by using a preset plasma.

13. A chip, characterized in that: The chip includes at least one gas sensor according to any one of claims 1 to 6.

14. An electronic device, characterized in that: The electronic device comprises a circuit board and the chip as claimed in claim 13; the chip is arranged on the circuit board.

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