Gas sensitive element preparation method, gas sensitive element, sensor chip, electronic equipment and vehicle

Abstract

The invention discloses a preparation method of a gas sensitive element, the gas sensitive element, a sensor chip, electronic equipment and a vehicle wherein the preparation method of the gas sensitive element comprises the following steps: providing a substrate, and preparing a plurality of photoresist protrusions on the base surface of the substrate to obtain the substrate with the plurality of photoresist protrusions; preparing a gas-sensitive film on the base surface of the substrate to obtain a semi-finished gas-sensitive element; and carrying out heat treatment on the semi-finished gas-sensitive element to remove the photoresist lug boss, thereby obtaining the primary gas-sensitive element with the porous gas-sensitive film. According to the preparation method of the gas sensitive element, the photoresist lug boss is removed in a heat treatment manner, so that the sensitivity of the gas sensitive element can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to a method for preparing a gas sensing element, a gas sensing element, a sensor chip, an electronic device and a vehicle. Background Art

[0002] Cars emit a large amount of toxic and harmful exhaust gas, such as CO, NO2, SO2, etc., while driving. When these gases reach a certain concentration and are inhaled by people in the car, they will cause great harm to human health. Therefore, it is urgent to develop a gas sensor to monitor the concentration of these toxic gases, so as to automatically control the internal and external circulation of the car air conditioner. MEMS gas sensor chips are widely used in vehicle air quality monitoring systems due to their small size, low power consumption and high integration.

[0003] In a MEMS gas sensor chip, the most important part is the sensitive material layer. To improve the sensitivity of the sensor, researchers usually use gas-sensitive films deposited by magnetron sputtering. The films deposited by magnetron sputtering have high consistency and strong controllability, which can significantly improve the consistency of the gas-sensitive performance of the sensor. However, since the sensitive film obtained by magnetron sputtering is very dense, the gas to be measured cannot enter the interior of the gas-sensitive film, resulting in poor sensitivity. Summary of the invention

[0004] The first object of the present invention is to provide a new technical solution for a method for preparing a gas sensor, which can at least solve the technical problem of poor sensitivity of existing gas sensors.

[0005] The second object of the present invention is to provide a gas sensor prepared by the above method.

[0006] The third object of the present invention is to provide a sensor chip comprising the above-mentioned gas sensing element.

[0007] A fourth object of the present invention is to provide an electronic device comprising the above-mentioned sensor chip.

[0008] A fifth object of the present invention is to provide a vehicle comprising a gas sensitive element or a sensor chip prepared by the above method.

[0009] According to a first aspect of the present invention, a method for preparing a gas sensitive element is provided, comprising the following steps: providing a substrate, preparing a plurality of photoresist protrusions on a base surface of the substrate, to obtain a substrate having a plurality of photoresist protrusions; preparing a gas sensitive film on the base surface of the substrate, to obtain a semi-finished gas sensitive element; and heat-treating the semi-finished gas sensitive element to remove the photoresist protrusions, to obtain a primary gas sensitive element having a porous gas sensitive film.

[0010] Optionally, a plurality of photoresist protrusions are prepared on the base surface of the base, and the steps of obtaining the base having the plurality of photoresist protrusions include: providing a mask having a plurality of through holes, and placing the mask on the base surface of the base; preparing a photoresist layer matching the through holes on the base surface through the through holes; exposing and developing the photoresist layer so that the photoresist layer forms the photoresist protrusions; and removing the mask to obtain a base having the plurality of photoresist protrusions.

[0011] Optionally, the step of preparing a plurality of photoresist protrusions on the base surface of the substrate includes: preparing a photoresist layer on the base surface of the substrate to obtain a substrate having a photoresist layer; providing a mask having a plurality of through holes, and placing the mask on the surface of the photoresist layer; exposing and developing the photoresist layer through the mask to obtain a primary photoresist protrusion.

[0012] Optionally, the step of preparing a plurality of photoresist protrusions on the base surface of the substrate further comprises: baking the developed photoresist layer to obtain secondary photoresist protrusions.

[0013] Optionally, a photoresist layer is prepared on the base surface of the substrate to obtain a substrate having a photoresist layer, the step comprising: spin coating the photoresist on the base surface of the substrate; baking the photoresist at a baking temperature of 50°C to 100°C for a baking time of 1h to 2h to obtain a substrate having a photoresist layer.

[0014] Optionally, the photoresist layer has a thickness of 500nm to 1000nm.

[0015] Optionally, the thickness of the gas-sensitive film is 100 nm to 500 nm.

[0016] Optionally, the substrate is a micro hot plate.

[0017] Optionally, the temperature of the heat treatment of the semi-finished gas sensing element is the temperature at which the gas sensing film recrystallizes.

[0018] Optionally, the semi-finished gas sensor is heat treated at a temperature of 450° C. to 550° C. for a time of 1 h to 3 h.

[0019] Optionally, the step of preparing the gas-sensitive film on the base surface of the substrate includes: depositing a gas-sensitive target material on the base surface of the substrate to obtain the gas-sensitive film.

[0020] Optionally, the first end of the photoresist protrusion is arranged on the substrate, the second end of the photoresist protrusion is away from the substrate, and the projection of the second end of the photoresist protrusion on the substrate at least partially does not overlap with the projection of the first end of the photoresist protrusion on the substrate.

[0021] Optionally, the first end of the photoresist protrusion is arranged on the substrate, the second end of the photoresist protrusion is away from the substrate, and the radial dimension of the first end of the photoresist protrusion is smaller than the radial dimension of the second end of the photoresist protrusion.

[0022] Optionally, the photoresist protrusion is a straight cylinder, an oblique cylinder or an inverted cone.

[0023] Optionally, a diameter of one end of the photoresist protrusion close to the base surface is 500nm-1000nm, and a height of the photoresist protrusion is 500nm-1000nm.

[0024] Optionally, the method further comprises the following step: cleaning and drying the primary gas sensor to obtain a secondary gas sensor.

[0025] According to a second aspect of the present invention, a gas sensor is provided. The gas sensor is obtained by using the above-mentioned gas sensor preparation method.

[0026] Optionally, the first end of the pores of the porous gas-sensitive film is close to the substrate, the second end of the pores is far from the substrate, and the radial dimension of the first end of the pores is smaller than the radial dimension of the second end of the pores.

[0027] According to a third aspect of the present invention, a sensor chip is provided, comprising the above-mentioned gas sensing element.

[0028] According to a fourth aspect of the present invention, there is provided an electronic device comprising the above-mentioned sensor chip.

[0029] According to a fifth aspect of the present invention, a vehicle is provided, comprising the above-mentioned sensor chip or electronic device.

[0030] According to the method for preparing a gas-sensitive element of the present invention, a plurality of photoresist protrusions are used as sacrificial structures, and the photoresist protrusions are removed by heat treatment, so that a primary gas-sensitive element with a porous gas-sensitive film can be obtained. The porous structure facilitates gas to enter the interior of the gas-sensitive film, thereby improving the sensitivity of the gas-sensitive element. Moreover, the performance of the gas-sensitive film will be optimized during the heat treatment process, which can further improve the sensitivity of the gas-sensitive element, thereby improving the reliability of the gas-sensitive element.

[0031] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0033] Figure 1 is a flow chart of a method for preparing a gas sensor according to an embodiment of the present invention;

[0034] Figure 2 is a schematic diagram of spin coating photoresist on a substrate according to a method for preparing a gas sensor provided by an embodiment of the present invention;

[0035] Figure 3 is a schematic diagram of placing a mask on the surface of a photoresist layer according to an embodiment provided by the present invention;

[0036] Figure 4 is a schematic diagram of a substrate having a plurality of photoresist protrusions according to an embodiment of the present invention;

[0037] Figure 4a yes Figure 4 The enlarged schematic diagram of the middle circle A;

[0038] Figure 5 is a schematic diagram of a semi-finished gas sensor according to an embodiment of the present invention;

[0039] Figure 6 is a schematic structural diagram of a gas sensor according to an embodiment of the present invention;

[0040] Figure 7 Schematic diagram of the structure of a sensor chip according to an embodiment of the present invention.

[0041] Reference numerals:

[0042] Sensor chip 100;

[0043] Base 10;

[0044] Photoresist layer 20; Photoresist protrusion 21;

[0045] Gas sensitive film 30; porous gas sensitive film 31;

[0046] Mask plate 40; test electrode 50; heating electrode 60. DETAILED DESCRIPTION

[0047] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0048] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0049] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0050] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0051] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0052] The following first describes in detail the method for preparing a gas sensor according to an embodiment of the present invention with reference to the accompanying drawings.

[0053] like Figures 1 to 6 As shown, the method for preparing a gas sensor according to an embodiment of the present invention includes: steps 100 to 300.

[0054] Step 100 : providing a substrate 10 , preparing a plurality of photoresist protrusions 21 on a base surface of the substrate 10 , and obtaining a substrate 10 having a plurality of photoresist protrusions 21 .

[0055] Specifically, a required substrate 10 is provided, and a central local surface on one side of the substrate 10 can be used as a base surface. A plurality of photoresist protrusions 21 as sacrificial structures are prepared on the base surface of the substrate 10. The photoresist protrusions 21 can be cylindrical structures. The plurality of photoresist protrusions 21 can be equidistantly arranged on the base surface, for example, in the form of a matrix, thereby obtaining a substrate 10 having a plurality of photoresist protrusions 21.

[0056] Step 200: Prepare a gas-sensitive film 30 on the base surface of the substrate 10 to obtain a semi-finished gas-sensitive element.

[0057] That is to say, on the base surface of the substrate 10 having multiple photoresist protrusions 21, a magnetron sputtering device or other equipment is used to cover the gas-sensitive material on the portion of the substrate 10 not covered by the photoresist protrusions 21, thereby forming a gas-sensitive film 30 on the portion of the base surface not covered by the photoresist protrusions 21, thereby obtaining a substrate 10 with a gas-sensitive film 30, that is, a semi-finished gas-sensitive element.

[0058] Step 300 , heat-treating the semi-finished gas sensor to remove the photoresist protrusion 21 , thereby obtaining a primary gas sensor having a porous gas-sensitive film 31 .

[0059] Specifically, the semi-finished gas sensor is placed in a muffle furnace for heat treatment. The temperature and time of the heat treatment can be determined according to the specific material and melting point of the photoresist. When the semi-finished gas sensor is heat treated, the photoresist protrusion 21 on the base surface will melt to form a liquid. The base surface can face downward, so that the liquid formed after the photoresist protrusion 21 melts will fall from the substrate 10 and the gas-sensitive film 30, thereby obtaining a primary gas sensor with a porous gas-sensitive film 31, and the performance of the gas-sensitive film 30 will be optimized during the heat treatment.

[0060] Therefore, according to the method for preparing a gas-sensitive element according to an embodiment of the present invention, a plurality of photoresist protrusions 21 are used as sacrificial structures, and the photoresist protrusions 21 are removed by heat treatment, so that a primary gas-sensitive element having a porous gas-sensitive film 31 can be obtained. The porous structure facilitates gas to enter the interior of the gas-sensitive film 30, thereby improving the sensitivity of the gas-sensitive element. Moreover, the performance of the gas-sensitive film 30 will be optimized during the heat treatment process, which can further improve the sensitivity of the gas-sensitive element, thereby improving the reliability of the gas-sensitive element.

[0061] In some examples of the present invention, the gas-sensitive material is a metal oxide, such as SnO2, WO3, In2O3.

[0062] In some specific embodiments of the present invention, the photoresist protrusion 21 is made of negative photoresist, and the negative photoresist may be, but is not limited to, SU-8, AZ5214, or S1805.

[0063] According to one embodiment of the present invention, the steps of preparing a plurality of photoresist protrusions 21 on the base surface of the base 10 to obtain the base 10 having the plurality of photoresist protrusions 21 include: steps 110 to 140 .

[0064] Step 110 , providing a mask plate 40 having a plurality of through holes, and placing the mask plate 40 on the base surface of the substrate 10 .

[0065] Specifically, a required mask plate 40 is provided, the mask plate 40 has a plurality of through holes extending through the mask plate 40 along its thickness direction, and the shape and arrangement of the through holes can be determined according to the shape and distribution of the required photoresist protrusions 21; the mask plate 40 is disposed on the base surface of the substrate 10 so that the mask plate 40 covers the base surface of the substrate 10, thereby exposing only the portions of the base surface corresponding to the plurality of through holes.

[0066] In this embodiment, the thickness of the mask plate 40 can be selected according to the required height of the photoresist protrusion 21 .

[0067] Step 120 , preparing a photoresist layer 20 on the base surface through the through hole and matching the through hole.

[0068] That is to say, photoresist can be spin-coated on the side of the mask 40 away from the substrate 10. During the spin-coating process, the portion of the base surface corresponding to the through hole will form a photoresist layer 20 that matches the through hole. After the photoresist is spin-coated, the substrate 10 is placed in a forced air drying oven for baking to remove most of the solution in the photoresist and fix the exposure characteristics of the photoresist.

[0069] Step 130 , exposing the photoresist layer 20 to form a photoresist protrusion 21 on the photoresist layer 20 .

[0070] Specifically, the photoresist layer 20 is exposed using high-energy radiation, and the high-energy radiation source may be, but is not limited to, ultraviolet rays, electron beams, and X-rays. After exposure, the chemical and mechanical properties of the photoresist layer 20 are changed, and the exposed photoresist layer 20 undergoes cross-linking and polymerization, thereby forming the desired photoresist protrusions 21 on the base surface.

[0071] Step 140 , removing the mask 40 to obtain a substrate 10 having a plurality of photoresist protrusions 21 .

[0072] In detail, after the photoresist layer 20 is cross-linked and polymerized, the mask 40 is removed from the base surface to obtain the base 10 having a plurality of photoresist protrusions 21 .

[0073] In this embodiment, there will be no problem of residual photoresist after the photoresist protrusion 21 is removed from the base surface, thereby ensuring the subsequent connection strength between the gas sensitive film 30 and the base 10 .

[0074] like Figures 1 to 6 As shown, in some specific embodiments of the present invention, a plurality of photoresist protrusions 21 are prepared on the base surface of the substrate 10 , and the steps of obtaining the substrate 10 having the plurality of photoresist protrusions 21 include: steps 150 to 170 .

[0075] Step 150, preparing a photoresist layer 20 on the base surface of the substrate 10 to obtain the substrate 10 having the photoresist layer 20;

[0076] The thickness of the photoresist layer 20 can be adjusted independently, and can be specifically determined according to the required height of the photoresist protrusion 21 .

[0077] Step 160 , providing a mask plate 40 having a plurality of through holes, and placing the mask plate 40 on the surface of the photoresist layer 20 .

[0078] Specifically, a required mask template 40 is provided, and the mask template 40 has a plurality of through holes penetrating along its thickness direction, and the shape and arrangement of the through holes can be determined according to the shape and distribution of the required photoresist protrusions 21; the mask template 40 is set on the surface of the photoresist layer 20, so that the mask template 40 covers the photoresist layer 20, so that only the portions of the photoresist layer 20 corresponding to the plurality of through holes are exposed.

[0079] Step 170 , exposing and developing the photoresist layer 20 through the mask plate 40 to obtain a primary photoresist protrusion 21 .

[0080] In detail, first, the photoresist layer 20 is exposed using high-energy radiation. The high-energy radiation source may be, but is not limited to, ultraviolet rays, electron beams, and X-rays. After exposure, the chemical and mechanical properties of the photoresist layer 20 are changed, and the exposed photoresist layer 20 undergoes cross-linking polymerization to form a photoresist protrusion 21 that is insoluble in a developer. Then, the substrate 10 is placed in a developer, and the unexposed portion of the photoresist layer 20 is dissolved, so that the unexposed portion of the photoresist layer 20 is separated from the substrate 10 and the photoresist protrusion 21, thereby exposing the desired primary photoresist protrusion 21.

[0081] In this embodiment, the mask plate 40 and the photoresist layer 20 are not connected, which is convenient for subsequent reuse and can effectively reduce production costs.

[0082] According to one embodiment of the present invention, the step of preparing a plurality of photoresist protrusions 21 on the base surface of the substrate 10 further includes: step 180 .

[0083] Step 180 , baking the developed photoresist layer 20 to obtain a secondary photoresist protrusion 21 .

[0084] That is to say, the substrate 10 with the primary photoresist protrusion 21 can be placed in an oven for baking. The baking temperature can be 100°C to 150°C, and the baking time can be 2h to 4h. In this way, the remaining solution on the substrate 10 and the primary photoresist protrusion 21 can be removed more quickly, and the secondary photoresist protrusion 21 with a more firmly bonded substrate 10 can be obtained.

[0085] In this embodiment, the photoresist protrusion 21 can be effectively prevented from falling off from the substrate 10 during the subsequent production process, thereby improving the yield of the gas sensor.

[0086] In some specific embodiments of the present invention, the step of preparing the photoresist layer 20 on the base surface of the substrate 10 to obtain the substrate 10 having the photoresist layer 20 includes: step 151 and step 152 .

[0087] Step 151, spin coating photoresist on the base surface of the substrate 10;

[0088] Among them, the material and thickness of the photoresist can be determined according to actual needs, and will not be repeated in this embodiment.

[0089] Step 152 , baking the photoresist at a temperature of 50° C. to 100° C. for a time of 1 h to 2 h, to obtain a substrate 10 having a photoresist layer 20 .

[0090] That is to say, the substrate 10 spin-coated with photoresist can be placed in a forced air drying oven for baking, so that most of the solution in the photoresist can be quickly removed and the exposure characteristics of the photoresist can be fixed, and the substrate 10 with the photoresist layer 20 can be obtained more quickly. The connection strength between the photoresist layer 20 and the substrate 10 can be effectively improved, and the photoresist protrusion 21 can be effectively prevented from falling off from the substrate 10 during the subsequent production process, which can improve the yield of preparing gas-sensitive elements.

[0091] According to an embodiment of the present invention, the thickness of the photoresist layer 20 is 500 nm to 1000 nm, thereby preparing a photoresist protrusion 21 with a height of 500 nm to 1000 nm.

[0092] In some specific embodiments of the present invention, the thickness of the gas-sensitive film 30 is 100 nm to 500 nm, thereby preparing a porous gas-sensitive film 31 with a thickness of 100 nm to 500 nm.

[0093] In some examples of the present invention, the height of the photoresist protrusion 21 is greater than the thickness of the deposited gas-sensitive target material, and the difference may be no less than 400 nm, thereby further preventing the deposited gas-sensitive target material from being connected into pieces and failing to form a porous structure.

[0094] In some optional examples of the present invention, the substrate 10 is a micro-hotplate, thereby a gas-sensitive element having a micro-hotplate can be prepared, so that the porous gas-sensitive film 31 can be heated to a suitable temperature by the micro-hotplate, thereby improving the gas-sensitive properties.

[0095] According to one embodiment of the present invention, the temperature of the heat treatment of the semi-finished gas sensor is the temperature at which the gas sensing film 30 recrystallizes.

[0096] That is, the heat treatment temperature of the semi-finished gas sensor can be determined according to the recrystallization temperature of the gas sensor film 30, so that the gas sensor film 30 can be recrystallized during the heat treatment of the semi-finished gas sensor, thereby effectively improving the gas sensing performance of the gas sensor.

[0097] In some specific embodiments of the present invention, the semi-finished gas sensor is heat treated at a temperature of 450° C. to 550° C. for a time of 1 h to 3 h.

[0098] Specifically, the semi-finished gas sensor is placed in a muffle furnace and heated at a temperature of 450° C. to 550° C. for a heating time of 1 h to 3 h. After the heating is completed, it is cooled at room temperature to obtain a first-class gas sensor with good gas-sensing properties.

[0099] In some examples of the present invention, the step of preparing a gas-sensitive film on the base surface of the substrate 10 includes: step 210 .

[0100] Step 210 , depositing a gas-sensitive target material on the base surface of the substrate 10 to obtain a gas-sensitive film 30 .

[0101] Specifically, a magnetron sputtering device is used to deposit a gas-sensitive target material on the base surface of the substrate 10 having multiple photoresist protrusions 21. The gas-sensitive target material can be a powder with gas-sensitive properties. The gas-sensitive target material is sputtered and deposited onto the base surface of the substrate 10, so that the required gas-sensitive film 30 can be obtained on the portion of the base surface not covered by the photoresist protrusions 21.

[0102] According to one embodiment of the present invention, the first end of the photoresist protrusion 21 is disposed on the substrate 10, the second end of the photoresist protrusion 21 is away from the substrate 10, and the projection of the second end of the photoresist protrusion 21 on the substrate 10 does not overlap at least partially with the projection of the first end of the photoresist protrusion 21 on the substrate 10. For example, the photoresist protrusion 21 can be formed as a column and inclined to the base surface of the substrate 10, thereby effectively preventing the deposited gas-sensitive target material from being connected into pieces and failing to form a porous gas-sensitive film 30, thereby improving the production yield of the gas-sensitive element.

[0103] In some specific embodiments of the present invention, the first end of the photoresist protrusion 21 is disposed on the substrate 10 , the second end of the photoresist protrusion 21 is away from the substrate 10 , and the radial dimension of the first end of the photoresist protrusion 21 is smaller than the radial dimension of the second end of the photoresist protrusion 21 .

[0104] That is to say, the photoresist protrusion 21 can be formed into a protruding structure with one end large and the other end small, the smaller end of the photoresist protrusion 21 is arranged on the substrate 10, and the larger end of the photoresist protrusion 21 is far away from the substrate 10, so that when the gas-sensitive target material is deposited, the side wall of the photoresist protrusion 21 can be stopped by the larger end of the photoresist protrusion 21, thereby effectively preventing the gas-sensitive target material from being deposited on the side wall of the photoresist protrusion 21, and further effectively preventing the deposited gas-sensitive target material from being connected into pieces and unable to form a gas-sensitive film 30 with a porous structure, thereby effectively improving the production yield of the gas-sensitive element.

[0105] In some examples of the present invention, the photoresist protrusion 21 is a straight cylinder, an oblique cylinder or an inverted truncated cone, which can be formed by adjusting the photolithography process, such as adjusting the angle and intensity of the high-energy radiation source. When the photoresist protrusion 21 is an oblique cylinder or an inverted truncated cone, it can effectively prevent the gas-sensitive film 30 from being connected into a piece and failing to form a porous gas-sensitive film 30, thereby improving the production yield of the gas-sensitive element.

[0106] According to one embodiment of the present invention, the diameter of the end of the photoresist protrusion 21 close to the base surface is 500nm-1000nm, and the height of the photoresist protrusion 21 is 500nm-1000nm. The photoresist protrusion 21 with the above structural size can ensure the pore-forming effect of the gas-sensitive film 30, ensure that the gas-sensitive active sites of the gas-sensitive film 30 can be more exposed, and can effectively avoid the deposited gas-sensitive target material from being connected into pieces, thereby improving the production yield of the gas-sensitive element.

[0107] In some specific embodiments of the present invention, the method for preparing a gas sensor further includes: step 400.

[0108] Step 400: Clean and dry the primary gas sensor to obtain a secondary gas sensor.

[0109] Specifically, the first-level gas sensor is placed in an ultrasonic cleaning machine for ultrasonic cleaning for 10 minutes to 30 minutes. During this process, waste materials remaining on the first-level gas sensor can be removed, thereby effectively improving the sensitivity of the gas sensor and improving the reliability of the gas sensor.

[0110] In summary, according to the method for preparing a gas-sensitive element according to an embodiment of the present invention, a plurality of photoresist protrusions 21 are used as sacrificial structures, and the photoresist protrusions 21 are removed by heat treatment, so that a primary gas-sensitive element having a porous gas-sensitive film 31 can be obtained. The porous structure facilitates the entry of gas into the interior of the gas-sensitive film 30, thereby improving the sensitivity of the gas-sensitive element. Moreover, the performance of the gas-sensitive film 30 will be optimized during the heat treatment process, which can further improve the sensitivity of the gas-sensitive element, thereby improving the reliability of the gas-sensitive element.

[0111] The embodiment of the present invention further provides a gas sensor, which is obtained by using the gas sensor preparation method described in any of the above embodiments. Since the gas sensor preparation method according to the embodiment of the present invention has the above technical effects, the gas sensor according to the embodiment of the present invention also has the corresponding technical effects, that is, it has the advantages of high sensitivity, fast response speed and high reliability.

[0112] According to one embodiment of the present invention, the first end of the pores of the porous gas-sensitive film 31 is close to the substrate 10 , the second end of the pores is far from the substrate 10 , and the radial dimension of the first end of the pores is smaller than the radial dimension to the second end of the pores.

[0113] That is to say, the pores of the porous gas-sensitive film 31 of the gas-sensitive element of the embodiment of the present invention can be prepared into a pore body roughly in a trumpet structure by the above method. The porous gas-sensitive film 31 with such a structure has a high preparation yield. When preparing the porous gas-sensitive film 31 with such a structure, the photoresist protrusion 21 can be set as an inverted cone.

[0114] In this embodiment, the pores of the porous gas-sensitive film 31 are arranged in such a structure. Under the premise that the thickness of the porous gas-sensitive film 31 is constant, the contact area between the gas and the porous gas-sensitive film 31 can be increased, thereby improving the sensitivity of the gas-sensitive element.

[0115] like Figure 7 As shown, an embodiment of the present invention further provides a sensor chip 100, which can be a MEMS gas sensor chip 100, and the sensor chip 100 includes the gas-sensitive element described in any of the above embodiments. The sensor chip 100 is provided with a pair of test electrodes 50 on the surface of the substrate 10, and the test electrodes 50 can be electrically connected to the gas-sensitive film 30, so as to facilitate the connection of the sensor chip 100 and the test circuit; the sensor chip 100 is also provided with a pair of heating electrodes 60 on the surface of the substrate 10, and the heating electrodes 60 are electrically connected to the micro-hot plate, so as to facilitate the connection of the sensor chip 100 and the heating circuit.

[0116] Since the gas sensor according to the embodiment of the present invention has the above technical effects, the sensor chip 100 according to the embodiment of the present invention also has corresponding technical effects, that is, it has the advantages of high sensitivity, fast response speed and high reliability.

[0117] The embodiment of the present invention further provides an electronic device, comprising the sensor chip 100 described in the above embodiment. Since the sensor chip 100 according to the embodiment of the present invention has the above technical effects, the electronic device according to the embodiment of the present invention also has the corresponding technical effects, that is, it has the advantages of high sensitivity, fast response speed and high reliability.

[0118] The embodiment of the present invention further provides a vehicle, including the sensor chip 100 or the electronic device described in the above embodiment. Therefore, the electronic device according to the embodiment of the present invention also has the corresponding technical effect, that is, the air quality inside the vehicle can be detected in time, the detection effect is good, and the health of the driver and passengers can be effectively protected.

[0119] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A method for preparing a gas sensor, characterized in that: The following steps are involved: Providing a substrate, preparing a plurality of photoresist protrusions on a base surface of the substrate, to obtain a substrate having a plurality of photoresist protrusions; Prepare a gas-sensitive film on the base surface of the substrate to obtain a semi-finished gas-sensitive element; The semi-finished gas-sensitive element is subjected to heat treatment to remove the protruding portion of the photoresist, thereby obtaining a primary gas-sensitive element having a porous gas-sensitive film.

2. The method for preparing a gas sensor according to claim 1, characterized in that: The step of preparing a plurality of photoresist protrusions on the base surface of the base to obtain a base having a plurality of photoresist protrusions comprises: Providing a mask having a plurality of through holes, and placing the mask on a base surface of the substrate; Preparing a photoresist layer on the base surface through the through hole and matching the through hole; exposing and developing the photoresist layer so that the photoresist layer forms the photoresist protrusion; The mask is removed to obtain a substrate having a plurality of photoresist protrusions.

3. The method for preparing a gas sensor according to claim 1, characterized in that: The step of preparing a plurality of photoresist protrusions on the base surface of the base body comprises: Preparing a photoresist layer on the base surface of the substrate to obtain a substrate having the photoresist layer; Providing a mask having a plurality of through holes, and placing the mask on the surface of the photoresist layer; The photoresist layer is exposed and developed through the mask to obtain a primary photoresist protrusion.

4. The method for preparing a gas sensor according to claim 3, characterized in that: The step of preparing a plurality of photoresist protrusions on the base surface of the base body also includes: The developed photoresist layer is baked to obtain a secondary photoresist protrusion.

5. The method for preparing a gas sensor according to claim 3, characterized in that: The step of preparing a photoresist layer on the base surface of the base to obtain the base having the photoresist layer comprises: Spin coating photoresist on the base surface of the substrate; The photoresist is baked at a temperature of 50° C. to 100° C. for a time of 1 h to 2 h to obtain a substrate having a photoresist layer.

6. The method for preparing a gas sensor according to claim 3, characterized in that: The thickness of the photoresist layer is 500nm-1000nm.

7. The method for preparing a gas sensor according to claim 1, characterized in that: The thickness of the gas-sensitive film is 100nm-500nm.

8. The method for preparing a gas sensor according to claim 1, characterized in that: The substrate is a micro hot plate.

9. The method for preparing a gas sensor according to claim 1, characterized in that: The temperature of heat treatment on the semi-finished gas sensing element is the temperature at which the gas sensing film is recrystallized.

10. The method for preparing a gas sensor according to claim 9, characterized in that: The semi-finished gas sensor is heat treated at a temperature of 450° C. to 550° C. for a time of 1 hour to 3 hours.

11. The method for preparing a gas sensor according to claim 1, characterized in that: The step of preparing a gas-sensitive film on the base surface of the substrate comprises: A gas-sensitive target material is deposited on the base surface of the substrate to obtain a gas-sensitive film.

12. The method for preparing a gas sensor according to claim 1, characterized in that: The first end of the photoresist protrusion is arranged on the substrate, the second end of the photoresist protrusion is far away from the substrate, and the projection of the second end of the photoresist protrusion on the substrate does not overlap with the projection of the first end of the photoresist protrusion on the substrate at least in part.

13. The method for preparing a gas sensor according to claim 1, characterized in that: The first end of the photoresist protrusion is arranged on the substrate, the second end of the photoresist protrusion is away from the substrate, and the radial dimension of the first end of the photoresist protrusion is smaller than the radial dimension of the second end of the photoresist protrusion.

14. The method for preparing a gas sensor according to claim 1, characterized in that: The photoresist protrusion is a straight cylinder, an oblique cylinder or an inverted truncated cone.

15. The method for preparing a gas sensor according to claim 14, characterized in that: The diameter of one end of the photoresist protrusion close to the base surface is 500nm-1000nm, and the height of the photoresist protrusion is 500nm-1000nm.

16. The method for preparing a gas sensor according to any one of claims 1 to 15, characterized in that: The following steps are also included: The first-level gas sensor is cleaned and dried to obtain a second-level gas sensor.

17. A gas sensor, characterized in that: The gas sensor is obtained by the gas sensor preparation method according to any one of claims 1 to 16.

18. The gas sensor according to claim 17, characterized in that: The first end of the pores of the porous gas-sensitive film is close to the substrate, the second end of the pores is far away from the substrate, and the radial dimension of the first end of the pores is smaller than the radial dimension of the second end of the pores.

19. A sensor chip, characterized in that: Comprising the gas sensing element according to claim 17 or 18.

20. An electronic device, characterized in that: Comprising the sensor chip according to claim 19.

21. A vehicle, characterized in that: Includes the sensor chip according to claim 19, or the electronic device according to claim 20.

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