A semiconductor gas sensor chip and its preparation method and application

Abstract

The present application provides a semiconductor gas sensor chip and its preparation method and application. The chip includes: a substrate layer, a sensitive material layer, a filter layer and foam ceramics; the sensitive material layer includes Pd-SnO2, Pd-In2O3 and Pd-WO3; the filter layer includes the following preparation raw materials: Pd source, nonafluorohexyltrimethoxysilane and HZSM-5 molecular sieve. The present application obtains a sensor chip with excellent performance by regulating the sensitive material layer and the filter layer.

Description

Technical Field

[0001] The present application relates to the technical field of gas sensors, and in particular to a semiconductor gas sensor chip and a preparation method and application thereof. Background Art

[0002] Methane is the main component of coal mine gas, natural gas, shale gas and biogas, but it is colorless, odorless, flammable and explosive, posing a potential threat during use. In order to better detect the methane content in the environment, it is necessary to develop a high-performance methane gas sensor.

[0003] Among the many types of gas sensors, the resistive gas sensor with semiconductor metal oxide as the sensitive material has the advantages of low cost, simple preparation process, good stability and high sensitivity, and is currently one of the most widely used gas sensors. Metal oxide semiconductor (MOS) sensors have many advantages over other types of sensors, such as small size, low cost, easy integration and stability.

[0004] Among MOS materials, SnO2 is the first MOS material that can be used for methane detection and is also the material with the best response to methane, and is considered to be one of the most promising gas sensing materials. Pure tin oxide sensors still have some disadvantages, such as low sensitivity, long recovery time, poor stability and poor selectivity. Summary of the invention

[0005] The present application is made in view of the above-mentioned problems, and its object is to provide a semiconductor gas sensor chip having high sensitivity.

[0006] The first aspect of the present application provides a semiconductor gas sensor chip, comprising:

[0007] Substrate layer, sensitive material layer, filter layer and foam ceramic;

[0008] The sensitive material layer includes Pd-SnO2, Pd-In2O3 and Pd-WO3;

[0009] The filter layer comprises the following preparation materials:

[0010] Pd source, nonafluorohexyltrimethoxysilane and HZSM-5 molecular sieve.

[0011] According to one of the technical solutions of the sensor chip in this application, at least the following beneficial effects are achieved:

[0012] In the present application, modified HZSM-5 molecular sieve and foam ceramic are used for gas filtration; wherein, the foam ceramic performs preliminary filtration on the gas, and the modified HZSM-5 molecular sieve performs secondary filtration on the gas, thereby greatly reducing the influence of other gases on methane detection.

[0013] At the same time, the specific surface area of ​​the modified HZSM-5 molecular sieve is higher than that of the material in the sensitive material layer. The loose porosity of the modified HZSM-5 molecular sieve is conducive to the filtration and diffusion of the gas. At the same time, the contact part of the modified HZSM-5 molecular sieve in the filtration layer and the sensitive material layer penetrate each other, which is more conducive to the diffusion of methane gas and allows the gas to more fully contact the material surface, thereby improving the response to methane gas.

[0014] The surface of HZSM-5 molecular sieve contains Si(Al)-OH. The hydroxyl groups produced by the hydrolysis of organic silicon compounds undergo condensation reaction with the hydroxyl groups on the surface of HZSM-5 molecular sieve, thereby being deposited on the surface of HZSM-5 molecular sieve. After high-temperature calcination, a silica film is formed, which covers the acidic sites on the surface of HZSM-5 molecular sieve. At the same time, the silicon-aluminum ratio of HZSM-5 molecular sieve is also increased, thereby improving the hydrophobicity of the molecular sieve; it is beneficial to the transmission of non-polar gases, thereby improving the response to methane gas.

[0015] Pd-modified HZSM-5 molecular sieve achieves high sensitivity and selectivity to methanol gas.

[0016] The present application also increases the specific surface area of ​​the sensitive material layer by loading Pd on the surface of SnO2, In2O3 and WO3, thereby increasing the ability of the surface to adsorb reducing gas, thereby increasing the sensitivity to CH4.

[0017] The present application greatly improves the sensitivity of the sensor chip to methane by reasonably matching the sensitive material layer and the filter layer.

[0018] According to some embodiments of the present application, the filter layer includes the following preparation raw materials in parts by weight:

[0019] 10 parts of HZSM-5 molecular sieve, 0.1 to 0.5 parts of Pd source and 0.5 to 1 parts of nonafluorohexyltrimethoxysilane.

[0020] According to some embodiments of the present application, the Pd source includes PdN4H 12 Cl2.

[0021] According to some embodiments of the present application, the mass ratio of Pd-SnO2, Pd-In2O3 and Pd-WO3 in the sensitive material layer is 1:0.2~0.4:0.3~0.5.

[0022] According to some embodiments of the present application, the foam ceramic includes the following preparation raw materials:

[0023] Alumina, magnesium oxide, starch and kaolin.

[0024] According to some embodiments of the present application, the foam ceramic includes the following preparation raw materials in parts by weight:

[0025] 50 parts of aluminum oxide, 4 to 5 parts of magnesium oxide, 35 to 45 parts of starch and 5 to 10 parts of kaolin.

[0026] According to some embodiments of the present application, an electrode layer is further provided between the substrate layer and the sensitive material layer.

[0027] According to some embodiments of the present application, the electrode layer includes a gold electrode.

[0028] The second solution of the present application provides a method for preparing the semiconductor gas sensor chip of the first aspect of the present application, comprising the following steps:

[0029] A sensitive material layer, a filter layer and foam ceramics are formed on the surface of the substrate layer.

[0030] According to some embodiments of the present application, the method for preparing the filter layer comprises the following steps:

[0031] The HZSM-5 molecular sieve, Pd source and water are mixed and dried at 70°C to 90°C, and then calcined at 500°C to 600°C for 1h to 3h in a hydrogen atmosphere to obtain the calcined HZSM-5 molecular sieve;

[0032] Mixing the calcined HZSM-5 molecular sieve and aqueous ammonia to prepare a first mixture;

[0033] The mass volume ratio of the calcined HZSM-5 molecular sieve and ammonia water is 1g:40mL~60mL;

[0034] Nonafluorohexyltrimethoxysilane is added to the first mixture, and the mixture is reacted at 120° C. to 140° C. for 20 h to 30 h. After the reaction is completed, the solid and liquid are separated, and the solid phase is collected.

[0035] According to some embodiments of the present application, the method for preparing Pd-SnO2 comprises the following steps:

[0036] The tin dioxide, ammonium vanadate and aqueous ammonia are mixed to prepare a tin source mixture;

[0037] The dichlorotetraamminepalladium solution and the tin source mixture are then mixed, concentrated to dryness, and annealed.

[0038] According to some embodiments of the present application, the mass ratio of tin dioxide to ammonium vanadate is 10:1~2.

[0039] According to some embodiments of the present application, the mass ratio of tin dioxide to tetraamminepalladium dichloride is 100:1-2.

[0040] According to some embodiments of the present application, the annealing temperature is 500°C to 600°C.

[0041] According to some embodiments of the present application, the annealing atmosphere is an oxidizing atmosphere.

[0042] According to some embodiments of the present application, the annealing time is 2h~3h.

[0043] According to some embodiments of the present application, the method for preparing Pd-In2O3 comprises the following steps:

[0044] Indium oxide, dichlorotetraamminepalladium, propylene glycol and water are mixed and then ball-milled. After the ball-milling is completed, the mixture is dried and sintered.

[0045] According to some embodiments of the present application, the sintering temperature is 500°C to 600°C.

[0046] According to some embodiments of the present application, the sintering time is 1 h to 2 h.

[0047] According to some embodiments of the present application, the mass ratio of indium oxide to dichlorotetraamminepalladium is 100:1-2.

[0048] According to some embodiments of the present application, the method for preparing Pd-WO3 comprises the following steps:

[0049] S1. Mix sodium tungstate, oxalic acid, acetic acid and hydrochloric acid, perform hydrothermal reaction, and collect the solid phase by solid-liquid separation;

[0050] S2, mixing the solid phase, ascorbic acid and palladium chloride solution and reacting them, and calcining them after the reaction is completed.

[0051] According to some embodiments of the present application, the temperature of the hydrothermal reaction is 170°C to 180°C.

[0052] According to some embodiments of the present application, the hydrothermal reaction time is 12h~14h.

[0053] According to some embodiments of the present application, the temperature of the reaction in step S2 is 60°C~70°C.

[0054] According to some embodiments of the present application, the reaction time in step S2 is 6h~8h.

[0055] According to some embodiments of the present application, the calcination temperature in step S2 is 300°C to 400°C.

[0056] According to some embodiments of the present application, the calcination time in step S2 is 1 h to 2 h.

[0057] According to some embodiments of the present application, the mass ratio of sodium tungstate to oxalic acid is 10:3~4.

[0058] According to some embodiments of the present application, the mass ratio of sodium tungstate to palladium chloride is 100:2~4.

[0059] According to some embodiments of the present application, the method for preparing the foam ceramic comprises the following steps:

[0060] Alumina, magnesia, starch, kaolin and water are mixed, pressed, dried and sintered.

[0061] According to some embodiments of the present application, the pressing pressure is 15 MPa~25 MPa.

[0062] According to some embodiments of the present application, the drying temperature is 70°C to 90°C.

[0063] According to some embodiments of the present application, the sintering temperature is 1200°C to 1400°C.

[0064] According to some embodiments of the present application, the sintering time is 1 h to 3 h.

[0065] The third aspect of the present application provides the use of the above-mentioned semiconductor gas sensor chip in the preparation of a gas sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the embodiments of the present drawings or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present drawings. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0067] Figure 1 This is a schematic diagram of the gas sensor performance test structure for this application.

[0068] The purpose, features and advantages of this figure will be further described in conjunction with the embodiments with reference to the accompanying drawings. DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0070] Obviously, the following descriptions are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in the field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0071] However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of substantially the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the following description is provided for those skilled in the art to fully understand the present application and is not intended to limit the subject matter described in the claims.

[0072] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0073] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0074] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0075] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0076] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0077] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0078] The preparation method of SnO2 in the examples and comparative examples of the present application consists of the following steps:

[0079] Stannous oxalate and hydrogen peroxide (molar ratio of 2:1) were mixed and reacted at 80°C. After the reaction was completed, the solid and liquid were separated and the solid phase was collected. The solid phase was placed in an air atmosphere (the air flow rate was 100 cm 3 / min) sintering (heating rate of 5℃ / min, holding temperature of 800℃, holding time of 2h); and naturally cool after sintering.

[0080] The preparation method of Pd-In2O3 in the examples and comparative examples of the present application consists of the following steps:

[0081] S1. Preparation of indium oxide:

[0082] Indium nitrate was oxidized in an air atmosphere (the air flow rate was 100 cm 3 / min), the oxidation temperature is 800℃, the heating rate is 5℃ / min, it is kept at 800℃ for 2h, cooled naturally, and the indium trioxide powder is collected.

[0083] S2, preparing a suspension containing metallic Pd by tetraamminedichloropalladium, glycerol and water (the mass volume ratio of tetraamminedichloropalladium to glycerol is 1 g:1 mL; the volume ratio of glycerol to water is 1:1), and ultrasonically oscillating (40 kHz, 120 W) for 30 min to obtain a Pd-containing mixture;

[0084] Then, indium trioxide is added to the Pd-containing mixture and ball-milled (the ball-milling time is 2 hours, and the mass ratio of dichlorotetraamminepalladium to indium trioxide is 1.5:100). After the ball-milling is completed, it is dried (dried at 60°C). After drying, the temperature is increased to 500°C at 5°C / min and kept at this temperature for 2 hours to obtain Pd-In2O3.

[0085] The preparation method of Pd-WO3 in the examples and comparative examples of the present application consists of the following steps:

[0086] Sodium tungstate dihydrate, oxalic acid dihydrate (the mass ratio of sodium tungstate to oxalic acid is 100:3.2), acetic acid (the mass volume ratio of sodium tungstate dihydrate to acetic acid is 1g:60mL) and hydrochloric acid (mass fraction is 35%, the volume ratio of acetic acid to hydrochloric acid is 30:1) are stirred evenly, and hydrothermally reacted at 180℃ for 12h. After the reaction is completed, the solid-liquid separation is carried out, and the solid phase is dried to obtain the solid phase;

[0087] The solid phase, palladium chloride solution (10 mM, 100:2.8) and ascorbic acid solution (20 mM, the volume ratio of palladium chloride solution to ascorbic acid solution is 1.5:1) were mixed and reacted at 60°C for 6 hours. After the reaction was completed, the solid and liquid were separated, and the solid phase was collected and calcined at 300°C for 1 hour.

[0088] Example 1

[0089] This embodiment is a semiconductor sensor chip, which is composed of a heating electrode, a substrate layer (aluminum oxide layer, with a thickness of 0.25 mm, a length and a width of 4 mm), an electrode layer, a sensitive material layer, a filter layer and foam ceramics from bottom to top;

[0090] A ceramic frame is arranged around the foam ceramic.

[0091] The heating electrode is a platinum heating electrode;

[0092] The electrode layer is a gold electrode;

[0093] The mass ratio of Pd-SnO2, Pd-In2O3 and Pd-WO3 in the sensitive material layer is 1:0.3:0.4.

[0094] The filter layer includes the following raw materials in parts by weight:

[0095] HZSM-5 molecular sieve 10 parts, Pd source (PdN4H 12 Cl2) 0.4 parts and nonafluorohexyltrimethoxysilane 0.8 parts.

[0096] The foam ceramic comprises the following raw materials in parts by weight:

[0097] 50 parts of aluminum oxide, 5 parts of magnesium oxide, 40 parts of starch and 8 parts of kaolin.

[0098] The preparation method of Pd-SnO2 in this embodiment consists of the following steps:

[0099] SnO2, ammonium vanadate (the mass ratio of SnO2 to ammonium vanadate is 10:1.8), ammonia water (mass fraction is 5%) and water are mixed, and stirred for 30 minutes at a temperature of 40°C, a pH of 9 (adjusted by ammonia water) and a stirring speed of 250 r / min to prepare a tin source mixture;

[0100] Dichlorotetraamminepalladium (the mass ratio of SnO2 to dichlorotetraamminepalladium is 10:1.2) and water are mixed, and stirred at a temperature of 40°C and a stirring speed of 250 r / min for 30 minutes to prepare a palladium source mixture;

[0101] The palladium source mixture was added dropwise to the tin source mixture, and stirred for 4 hours at a temperature of 40°C and a stirring speed of 250 r / min. After the stirring was completed, the solid and liquid were separated, and the solid phase was collected and dried;

[0102] After drying, the air flow rate is 100cm 3 / min, then heat to 500°C at 2°C / min, treat at 500°C for 2h, and cool in the furnace.

[0103] The preparation method of the filter layer in this embodiment consists of the following steps:

[0104] HZSM-5 molecular sieve, Pd source and water (the mass volume ratio of HZSM-5 molecular sieve to water is 1 g: 10 mL) were mixed, dried at 80 °C, and then calcined at 550 °C in a hydrogen atmosphere for 2 h;

[0105] Then, the calcined HZSM-5 molecular sieve and ammonia water (mass fraction is 5%, and the mass volume ratio of the calcined HZSM-5 molecular sieve and ammonia water is 1g:50mL) are mixed to prepare a first mixture;

[0106] Nonafluorohexyltrimethoxysilane was then mixed with the first mixture and reacted at 130° C. for 25 hours. After the reaction was completed, the solid and liquid were separated, and the solid phase was collected and dried at 80° C. for 12 hours.

[0107] The preparation method of the foam ceramic in this embodiment consists of the following steps:

[0108] Alumina (α-Al2O3, D50 is 5 μm), magnesium oxide (MgO, D50 is 5 μm), starch, kaolin (300 mesh) and water are mixed and ground, and then pressed (pressing pressure is 20 MPa) to obtain a disc with a diameter of 25 mm and a thickness of 1 mm;

[0109] The pressed discs were dried at 80°C for 24 hours, and then calcined at 1300°C in air atmosphere for 2 hours, and then naturally cooled after calcination.

[0110] In this embodiment, the semiconductor chip is used in the preparation of a methane gas sensor, and the specific preparation process is as follows:

[0111] (1) Preparation of planar electrodes

[0112] The platinum slurry is printed on the substrate layer using screen printing technology, leveled in the air for 10 minutes, dried for 30 minutes, and then placed in a box-type sintering furnace for annealing at 850°C for 10 minutes to obtain a stable platinum heating electrode; the same method is used to obtain a stable gold electrode layer; finally, the platinum wire is bonded to the heating electrode and the measuring electrode layer with gold slurry, and the temperature is raised to 850°C at 5°C / min in a box-type sintering furnace and maintained for 10 minutes to obtain the required planar electrode.

[0113] (2) Preparation of gas sensitive sensing membrane

[0114] Glycerol was added dropwise to the powder of the sensitive material layer (the mass volume ratio of the powder of the sensitive material layer to glycerol was 1 g: 1 mL), and ground in an agate mortar for 20 min to fully mix it to form a slurry that can be used for screen printing; then the slurry was printed on one side of the electrode layer using a desktop screen printer, dried at a constant temperature of 90°C for 30 min, and heated to 500°C at 5°C / min in a box-type sintering furnace under air conditions and maintained for 2 h to obtain a planar electrode with a sensitive material.

[0115] (3) Assembling devices

[0116] The ceramic support frame, filter layer and foam ceramic were bonded to the planar electrode with sensitive material in sequence using glass slurry, and the temperature was raised to 500°C at 5°C / min in a box furnace and maintained for 10 min to obtain a methane sensor chip.

[0117] The four leads of the sensor chip were welded to the corresponding base pins respectively and aged at 400°C for 24h to obtain a methane gas sensitive sensor.

[0118] Example 2

[0119] This embodiment is a semiconductor sensor chip, which is different from the first embodiment in that:

[0120] The mass ratio of Pd-SnO2, Pd-In2O3 and Pd-WO3 in the sensitive material layer is 1:0.4:0.3.

[0121] The filter layer includes the following raw materials in parts by weight:

[0122] HZSM-5 molecular sieve 10 parts, Pd source (PdN4H 12 Cl2) 0.5 parts and nonafluorohexyltrimethoxysilane 0.5 parts.

[0123] Example 3

[0124] This embodiment is a semiconductor sensor chip, which is different from the first embodiment in that:

[0125] The mass ratio of Pd-SnO2, Pd-In2O3 and Pd-WO3 in the sensitive material layer is 1:0.2:0.5.

[0126] The filter layer includes the following raw materials in parts by weight:

[0127] HZSM-5 molecular sieve 10 parts, Pd source (PdN4H 12 Cl2) 0.1 part and nonafluorohexyltrimethoxysilane 1 part.

[0128] Example 4

[0129] This embodiment is a semiconductor sensor chip, which is different from the first embodiment in that:

[0130] The mass ratio of Pd-SnO2, Pd-In2O3 and Pd-WO3 in the sensitive material layer is 1:0.2:0.3.

[0131] The filter layer includes the following raw materials in parts by weight:

[0132] HZSM-5 molecular sieve 10 parts, Pd source (PdN4H 12 Cl2) 0.5 parts and nonafluorohexyltrimethoxysilane 1 parts.

[0133] Example 5

[0134] This embodiment is a semiconductor sensor chip, which is different from the first embodiment in that:

[0135] The mass ratio of Pd-SnO2, Pd-In2O3 and Pd-WO3 in the sensitive material layer is 1:0.4:0.5.

[0136] The filter layer includes the following raw materials in parts by weight:

[0137] HZSM-5 molecular sieve 10 parts, Pd source (PdN4H 12 Cl2) 0.1 parts and nonafluorohexyltrimethoxysilane 0.5 parts.

[0138] Comparative Example 1

[0139] This comparative example is a semiconductor sensor chip, which differs from Example 5 in that:

[0140] The preparation method of Pd-SnO2 in this comparative example consists of the following steps:

[0141] SnO2, ammonia water (5% by mass) and water were mixed, and stirred for 30 minutes at a temperature of 40°C, a pH of 9 (adjusted by ammonia water) and a stirring speed of 250 r / min to prepare a tin source mixture;

[0142] Dichlorotetraamminepalladium (the mass ratio of SnO2 to dichlorotetraamminepalladium is 10:1.2) and water are mixed, and stirred at a temperature of 40°C and a stirring speed of 250 r / min for 30 minutes to prepare a palladium source mixture;

[0143] The palladium source mixture was added dropwise to the tin source mixture, and stirred for 4 hours at a temperature of 40°C and a stirring speed of 250 r / min. After the stirring was completed, the solid and liquid were separated, and the solid phase was collected and dried;

[0144] After drying, the air flow rate is 100cm 3 / min, then heat to 500°C at 2°C / min, treat at 500°C for 2h, and cool in the furnace.

[0145] Comparative Example 2

[0146] This comparative example is a semiconductor sensor chip, which differs from Example 5 in that:

[0147] The sensitive material layer is composed of Pd-SnO2 and Pd-In2O3 in a mass ratio of 1:0.3.

[0148] Comparative Example 3

[0149] This comparative example is a semiconductor sensor chip, which differs from Example 5 in that:

[0150] The sensitive material layer is composed of Pd-SnO2 and Pd-WO3 in a mass ratio of 1:0.4.

[0151] Comparative Example 4

[0152] This comparative example is a semiconductor sensor chip, which is different from Example 5 in that the filter layer includes the following raw materials in parts by weight:

[0153] HZSM-5 molecular sieve 10 parts and Pd source (PdN4H 12 Cl2) 0.1 part.

[0154] The preparation method of the filter layer in this comparative example consists of the following steps:

[0155] After mixing HZSM-5 molecular sieve, Pd source and water (the mass volume ratio of HZSM-5 molecular sieve to water is 1 g:10 mL), the solvent is dried at 80°C and then calcined at 550°C in a hydrogen atmosphere for 2 h.

[0156] Comparative Example 5

[0157] This comparative example is a semiconductor sensor chip, which is different from Example 5 in that no filter layer is added.

[0158] Gas Sensitive Performance Test Method

[0159] The gas sensor dynamic test system used in this application is as follows Figure 1 As shown in the figure, it mainly includes gas distribution system, sensor heating part, temperature and humidity control part and data acquisition part. The gas distribution part refers to the gas from the gas cylinder through the pressure reducing valve and gas mass flow controller (MFCs) to the mixing chamber, test chamber and temperature and humidity chamber. Different gases can be controlled by MFCs to control the proportion of gas flow (the total gas flow is set to 100mL / min) to obtain methane gas, interference gas and mixed gas of different concentrations.

[0160] The response value of the sensor is defined as Ra / Rg, where Ra and Rg represent the resistance of the sensor in air and in the test gas environment (the volume fraction of CO is 5*10 -4 , the volume fraction of CH4 is 5*10 -4 ) in the figure; the test results are shown in Table 1.

[0161] Table 1

[0162]

[0163] The difference between Comparative Example 1 and Example 5 is that ammonium vanadate is not added to Pd-SnO2, so Pd-SnO2 is not subjected to V modification treatment, while V modification treatment can adjust and optimize the performance of SnO2 intrinsic material, resulting in poor performance in Comparative Example 1.

[0164] The difference between Comparative Examples 2~3 and Example 5 is that Pd-WO3 is not added in Comparative Example 2, and Pd-In2O3 is not added in Comparative Example 3; the synergistic effect between Pd-SnO2, Pd-In2O3 and Pd-WO3 disappears, resulting in poor performance in Comparative Examples 2 and 3.

[0165] The difference between Comparative Example 4 and Example 5 is that the filter layer in Comparative Example 4 is not subjected to fluorine modification treatment, resulting in poor gas filtering ability and poor performance.

[0166] The difference between Comparative Example 5 and Example 5 is that no filter layer is provided in Comparative Example 5, resulting in poor gas filtering capability and poor performance.

[0167] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A semiconductor gas sensor chip, characterized in that: include: Substrate layer, sensitive material layer, filter layer and foam ceramic; The sensitive material layer includes Pd-SnO2, Pd-In2O3 and Pd-WO3; The mass ratio of Pd-SnO2, Pd-In2O3 and Pd-WO3 in the sensitive material layer is 1:0.2~0.4:0.3~0.5; The filter layer comprises the following raw materials in parts by weight: 10 parts of HZSM-5 molecular sieve, 0.1 to 0.5 parts of Pd source and 0.5 to 1 parts of nonafluorohexyltrimethoxysilane; The Pd source includes PdN4H 12 Cl2; The foam ceramic comprises the following raw materials in parts by weight: 50 parts of aluminum oxide, 4 to 5 parts of magnesium oxide, 35 to 45 parts of starch and 5 to 10 parts of kaolin; The substrate layer is an aluminum oxide layer; The preparation method of Pd-SnO2 comprises the following steps: The tin dioxide, ammonium vanadate and aqueous ammonia are mixed to prepare a tin source mixture; The dichlorotetraamminepalladium solution and the tin source mixture are then mixed, concentrated to dryness, and annealed; The annealing temperature is 500°C to 600°C; The mass ratio of tin dioxide to ammonium vanadate is 10:1-2; The mass ratio of tin dioxide to dichlorotetraamminepalladium is 100:1-2; The preparation method of the filter layer comprises the following steps: The HZSM-5 molecular sieve, Pd source and water are mixed and dried at 70°C to 90°C, and then calcined at 500°C to 600°C for 1h to 3h in a hydrogen atmosphere to obtain the calcined HZSM-5 molecular sieve; Mixing the calcined HZSM-5 molecular sieve and aqueous ammonia to prepare a first mixture; The mass volume ratio of the calcined HZSM-5 molecular sieve and ammonia water is 1g:40mL~60mL; Add nonafluorohexyltrimethoxysilane to the first mixture, react at 120° C. to 140° C. for 20 h to 30 h, separate the solid and liquid after the reaction is completed, and collect the solid phase; The method for preparing the foam ceramic comprises the following steps: Alumina, magnesia, starch, kaolin and water are mixed, pressed, dried and sintered; The pressing pressure is 15MPa~25MPa; The drying temperature is 70°C to 90°C; The sintering temperature is 1200°C to 1400°C; The sintering time is 1h~3h.

2. The semiconductor gas sensor chip according to claim 1, characterized in that: An electrode layer is also arranged between the substrate layer and the sensitive material layer.

3. The semiconductor gas sensor chip according to claim 2, characterized in that: The electrode layer includes a gold electrode.

4. The semiconductor gas sensor chip according to claim 1, characterized in that: The annealing atmosphere is an oxidizing atmosphere.

5. The semiconductor gas sensor chip according to claim 1, characterized in that: The annealing time is 2h~3h.

6. Use of the semiconductor gas sensor chip according to any one of claims 1 to 5 in preparing a gas sensor.

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