WO2020215654A1

WO2020215654A1 - Hot wire-type gas sensor chip, sensor and preparation method for sensor

Info

Publication number: WO2020215654A1
Application number: PCT/CN2019/115282
Authority: WO
Inventors: 崔铮; 张克栋; 刘福星; 余飞; 陈晓跃; 袁伟; 李亚邦
Original assignee: 苏州纳格光电科技有限公司
Priority date: 2019-04-23
Filing date: 2019-11-04
Publication date: 2020-10-29
Also published as: CN109932402A; JP2022530944A

Abstract

A hot wire-type gas sensor chip, comprising: a silicon substrate (11), which comprises a first surface (111) and a second surface (112) that are arranged opposite to each other, wherein the silicon substrate (11) comprises a central heating region (A) and a peripheral support region (B), and the central heating region (A) comprises an air insulation cavity (13) that penetrates the first surface (111) and the second surface (112); a heating resistance film (14), which is provided on the first surface (111); a heating electrode (12) which is provided on the first surface (111) and partially covers the heating resistance film (14); and a functional layer (15) which is provided above the heating resistance film (14) and located at the central heating region (A), wherein the functional layer (15) is a gas sensitive layer (151, 211) or an environmental compensation layer (152, 221).

Description

Hot wire type gas sensor chip, sensor and preparation method of sensor

Technical field

The invention relates to the technical field of electronic device manufacturing, in particular to a hot wire gas sensor chip, a sensor and a preparation method thereof.

Background technique

At present, there are many types of gas sensors and a wide range of applications. Among them, hot-wire gas sensors are composed of detection elements and compensation elements. They use semiconductor metal oxides as sensitive materials to retain the advantages of traditional semiconductor metal oxides with high sensitivity. The environmental temperature and humidity changes are compensated, so that the gas sensor has better environmental temperature and humidity stability.

Hot-wire semiconductor gas sensors are basically prepared by hand at present. The main process is: manually winding the platinum wire into a micro-coil with a specific length, and then manually applying the gas-sensitive material and the gas-insensitive material on the platinum wire coil and drying and sintering. Then, a gas-sensitive detection element and a gas-insensitive compensation element are obtained. The two elements form a hot-wire semiconductor gas sensor. The platinum wire coil is used as both a heating coil and a detection signal electrode in this type of sensor. This is also the origin of the name of the hot wire type. However, the hot-wire semiconductor gas sensor is basically prepared by hand, and the degree of automation is not high, resulting in low product yield, poor consistency, and high power consumption of the sensor, which limit the development and popularization of this type of sensor.

Summary of the invention

The purpose of the present invention is to provide a hot-wire type gas sensor chip, a sensor and a preparation method thereof.

In order to achieve the above-mentioned object of the invention, an embodiment of the present invention provides a hot-wire gas sensor chip, including: a silicon substrate, including a first surface and a second surface disposed oppositely; the silicon substrate including a central heating zone and a peripheral support zone, The central heating zone includes an air insulation cavity penetrating through the first surface and the second surface; a heating resistor film is provided on the first surface; a heating electrode is provided on the first surface and partially covers the A heating resistor film; a functional layer, arranged above the heating resistor film and located in the central heating zone, the functional layer being a gas sensitive layer or an environmental compensation layer.

As a further improvement of the present invention, the functional layer is a gas sensitive layer, and the gas sensitive layer is formed by sintering a gas sensitive slurry provided on the surface of the heating resistor film.

As a further improvement of the present invention, the material of the gas-sensitive slurry includes one or more of tin dioxide, zinc oxide, indium oxide or tungsten oxide, as well as precious metal catalysts and catalytic promoters.

As a further improvement of the present invention, the functional layer is an environmental compensation layer, and the environmental compensation layer is formed by sintering an environmental compensation slurry provided on the surface of the heating resistor film.

As a further improvement of the present invention, the material of the environmental compensation slurry includes tin dioxide, thorium dioxide, titanium dioxide, zirconium dioxide, ceria, indium oxide, lanthanum oxide, calcium oxide, barium oxide, aluminum oxide, two One or more of silicon oxide, magnesium oxide, hafnium dioxide, copper oxide, zinc oxide, and tungsten oxide.

As a further improvement of the present invention, the resistance value of the environmental compensation layer is not less than 10MΩ.

As a further improvement of the present invention, the thickness of the functional layer is 0.001um-20um.

As a further improvement of the present invention, the resistance value of the heating resistor film is 10Ω˜500Ω.

As a further improvement of the present invention, the heating electrode is formed by sintering a set metal conductive paste provided on the first surface.

As a further improvement of the present invention, the heating resistor film includes at least one first support portion, the heating electrode includes at least one second support portion covering the first support portion, and the first support portion and the first support portion The shape of the two supporting parts is the same. The first supporting part is formed by extending the part of the heating resistance film in the central heating zone to the peripheral supporting zone. The part of the peripheral support zone extends toward the central heating zone.

As a further improvement of the present invention, the width of the second supporting portion is less than or equal to the width of the first supporting portion.

Another aspect of the present invention provides a hot-wire gas sensor, including a packaging shell and at least two hot-wire gas sensor chips according to any one of the above arranged in the packaging shell; the packaging shell includes a base, and An opening above the base and an electrical connector arranged in the base; each of the hot-wire gas sensor chips is electrically connected to the base through the electrical connector.

As a further improvement of the present invention, the hot-wire gas sensor includes two hot-wire gas sensor chips, which are a detection element chip and a compensation element chip. The functional layer of the detection element chip is a gas sensitive layer, and the compensation element chip The functional layer is the environmental compensation layer.

As a further improvement of the present invention, the hot wire gas sensor further includes an explosion-proof, dust-proof and breathable membrane covering the opening, and the explosion-proof, dust-proof and breathable membrane is also provided with a waterproof and breathable membrane.

Another aspect of the present invention provides a method for preparing a hot wire gas sensor. The method includes the following steps: preparing a conductive metal oxide powder and an organic carrier into a ceramic paste, and printing or coating it on a silicon substrate to form Heating resistance film; printing or coating the heating electrode paste on the silicon substrate to form heating electrodes; forming an insulating air cavity on the silicon substrate by etching technology to obtain a micro hot plate; repeat the above steps to make another micro Hot plate; printing or coating a gas sensitive paste on one of the micro hot plates to form a gas sensitive layer; printing or coating an environment compensation paste on the other micro hot plate to form an environment Compensation layer; the two micro hot plates are respectively dried, sintered and cut to obtain the detection element chip and the compensation element chip; the detection element chip and the supplementary element chip are packaged in the shell, and the explosion-proof and anti-explosion protection are mounted on the opening of the shell Dust breathable membrane and waterproof breathable membrane.

Compared with the prior art, the hot wire gas sensor chip, sensor and sensor manufacturing method disclosed in the present invention are achieved by arranging a heating electrode, heating resistance film and functional layer on a silicon substrate, and setting the functional layer as a gas sensitive layer or The environmental compensation layer can make two hot-wire sensor chips with different functional layers, and package the two chips, so that the hot-wire gas sensor chip and sensor can be manufactured industrially; and the prepared hot-wire gas sensor adopts gas The chip of the sensitive layer is used as the detection element, and the chip with the environmental compensation layer is used as the compensation element, which can offset the influence of environmental temperature and humidity changes, and make the signal value of the sensor more stable.

Description of the drawings

1 is a schematic diagram of a cross-sectional structure of a hot wire gas sensor chip in an embodiment of the present invention;

2a is a schematic diagram of a cross-sectional structure of a detection element chip in an embodiment of the present invention;

2b is a schematic cross-sectional structure diagram of a compensation element chip in an embodiment of the present invention;

3 is a schematic diagram of a top view structure of a hot wire gas sensor chip in an embodiment of the present invention;

FIG. 4a is a schematic top view of the structure of a detection element chip in an embodiment of the present invention;

4b is a schematic top view of the structure of the compensation element chip in an embodiment of the present invention;

5 is a schematic diagram of a cross-sectional structure of a hot wire gas sensor in an embodiment of the present invention;

6 is a schematic diagram of a cross-sectional structure of a hot wire gas sensor in another embodiment of the present invention;

FIG. 7 is a schematic flowchart of a method for preparing a hot wire gas sensor in an embodiment of the present invention;

Fig. 8 is a graph showing the response curve of a hot wire gas sensor to methane in an embodiment of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the specific embodiments shown in the drawings. However, these embodiments do not limit the present invention, and the structural, method, or functional changes made by those skilled in the art based on these embodiments are all included in the protection scope of the present invention.

It should be understood that terms such as "upper", "above", "below", "below" and the like used herein to indicate a relative position in space are for the purpose of facilitating explanation to describe a unit or feature as shown in the accompanying drawings. Relationship to another unit or feature. The term of the relative position in space may be intended to include different orientations of the device in use or operation other than those shown in the figures.

As shown in FIGS. 1-4, an embodiment of the present invention discloses a hot wire gas sensor chip, which includes a silicon substrate 11, a heating electrode 12, a heating resistance film 14 and a functional layer 15. The silicon substrate 11 includes a first surface 111 and a second surface 112 opposite to each other. The silicon substrate 11 includes a central heating area A and a peripheral support area B. The central heating area A includes an air insulation cavity 13 penetrating through the first surface 111 and the second surface 112. The heating resistor film 14 is disposed on the first surface 111, and the heating electrode 12 is disposed on the first surface 111 and partially covers the heating resistor film 14. The functional layer is arranged above the heating resistor film 14 and located in the central heating zone, and the functional layer 15 is a gas sensitive layer or an environmental compensation layer.

The hot wire type gas sensor chip, sensor and sensor manufacturing method disclosed in the present invention can be fabricated by arranging heating electrodes, heating resistance films and functional layers on a silicon substrate, and setting the functional layers as a gas sensitive layer or an environmental compensation layer. A hot-wire sensor chip with different functional layers, and the two chips are encapsulated, so that a hot-wire gas sensor chip and sensor can be manufactured industrially; and the prepared hot-wire gas sensor uses a chip with a gas sensitive layer as the detection element , Using a chip with an environmental compensation layer as a compensation element can offset the impact of environmental temperature and humidity changes, making the signal value of the sensor more stable.

Preferably, the silicon substrate 11 is selected from double-sided oxidized, single-sided oxidized or unoxidized single crystal silicon wafers or polycrystalline silicon wafers, the crystal orientation of the single crystal silicon wafers is 100 or 111, and the thickness of the silicon substrate 11 is 100 um to 700 um, including Endpoint value.

Further, the heating resistor film 14 includes at least one first supporting portion 141, and the heating electrode 12 includes at least one second supporting portion 121 covering the first supporting portion 141, and the first supporting portion is connected to the The second supporting portion 121 has the same shape. The first supporting portion 141 extends from the portion of the heating resistor film 14 in the central heating area A to the peripheral supporting area B. The second supporting portion 121 is formed by The portion of the heating electrode located in the peripheral support area B extends toward the central heating area A.

Further, the width of the second supporting portion 121 is less than or equal to the width of the first supporting portion 141. Specifically, in the embodiment of the present invention, the shape and size of the second supporting portion 121 are completely the same as the shape and size of the first supporting portion.

Specifically, the functional layer 15 covers the surface of the heating resistor film 14. The second support portion 121 of the heating electrode 12 covers the first support portion 141 of the heating resistance film 14, thereby connecting the heating resistance film 14 and the silicon substrate 11. The heating resistor film 14 provides support for the functional layer 15 while conducting electricity. The air insulation cavity 13 penetrates the silicon substrate 11 and surrounds the heating electrode 12, the heating resistance film 14, the functional layer 15, and the first supporting portion 141 and the second supporting portion 121.

Specifically, the thickness of the functional layer 15 may be 0.001 um to 20 um, including the endpoint value.

Furthermore, as shown in FIG. 2a, the functional layer 15 is a gas sensitive layer 151, which is formed by sintering a gas sensitive paste provided on the surface of the heating resistor film 14. The gas-sensitive slurry is made of materials that are sensitive to the target gas. Specifically, the material of the gas-sensitive slurry includes one or more of tin dioxide, zinc oxide, indium oxide, or tungsten oxide, as well as precious metal catalysts and catalytic promoters.

Specifically, noble metal catalysts are the main participants in the catalytic reaction, including silver, gold, platinum, palladium, ruthenium, iridium, rhodium, europium, etc., including but not limited to these. Catalytic promoters are rare earth oxides and other metal oxides that can improve catalytic activity, such as thorium dioxide (ThO2), titanium dioxide (TiO2), zirconium dioxide (ZrO2), ceria (CeO2), antimony oxide (Sb2O3) , Lanthanum oxide (La2O3), calcium oxide (CaO), barium oxide (BaO), aluminum oxide (Al2O3), silicon dioxide (SiO2), magnesium oxide (MgO), hafnium dioxide (HfO2), copper oxide (CuO) Etc., including but not limited to this. By adjusting the doping ratio of the catalytic promoter, the resistance of the gas sensitive layer 151 at a specific working temperature is a specific resistance value from 5KΩ to 500KΩ.

Furthermore, as shown in FIG. 2b, the functional layer is an environmental compensation layer 152, and the environmental compensation layer 152 is formed by sintering the environmental compensation paste provided on the surface of the heating resistor film 14. The environmental compensation slurry is made of materials that are not sensitive to the target gas. Specifically, the material of the environment compensation slurry includes tin dioxide, thorium dioxide, titanium dioxide, zirconium dioxide, ceria, indium oxide, lanthanum oxide, calcium oxide, barium oxide, aluminum oxide, silicon dioxide, oxide One or more of magnesium, hafnium dioxide, copper oxide, zinc oxide, and tungsten oxide.

In the embodiment of the present invention, the resistance value of the environmental compensation layer 152 is not less than 10 MΩ.

Further, the heating resistance film 14 is made of antimony tin oxide, indium tin oxide, fluorine-doped tin dioxide, fluorine-phosphorus co-doped tin dioxide, aluminum-doped zinc oxide, ruthenium dioxide, two Any one of ruthenium oxide/silver composite material and ruthenium dioxide/silver palladium composite material. Preferably, the shape of the heating resistor film 14 is one or a combination of a rectangle, a square or a circle. Preferably, the resistance value of the heating resistor film 14 may be 10Ω˜500Ω, including the endpoint value. The thickness of the heating resistor film 14 may be 1um-50um, including the endpoint value.

Specifically, the heating resistor film 14 is prepared by screen printing conductive metal oxide paste and high temperature sintering, and the heating electrode is prepared by screen printing electrode paste and high temperature sintering. Preferably, the heating electrode 12 is formed by sintering a set metal conductive paste provided on the first surface. At this time, the heating electrode 12 is a conductive pad with a certain area, and the external circuit can be electrically connected to the heating electrode 12 through welding methods such as pressure welding, ball welding, spot welding, etc. The heating electrode 12 mainly provides external application for the micro hot plate. The heating resistor film 14 is made of conductive metal oxide paste. By adjusting different ratios, the heating resistor film 14 has a specific resistance. The heating resistor film 14 is the main heating element of the gas sensor. When the external current passes When the heating electrode 12 is transferred to the heating resistance film 14, the heating resistance film 14 generates Joule heat, which in turn provides a heat source for the hot wire gas sensor.

In order to make the hot wire gas sensor have a smaller heat capacity and a faster thermal response, the heating resistor film 14 is arranged as a suspension film, and is connected to the second support portion 121 of the heating electrode 12 through the first support portion 141. A supporting portion 141 and a second supporting portion 121 function to support and fix the heating resistor film 14 and form an electrical connection with the heating resistor film 14. Through the etching technology, the silicon in the central heating zone on the silicon substrate 11 is etched away to form an air insulation cavity 13. Since air has a low thermal conductivity, it has good thermal insulation. The deep silicon etching technology is used to form the air insulation cavity 13, and the silicon substrate 11 corresponding to the central heating zone A can be etched by physical or chemical methods to form the air insulation cavity. The shape of the heating resistor film 14 is appropriately adjusted according to the requirements of the heating layer, but no matter what shape it is, the heating electrode 12 and the heating resistor film 14 are electrically connected, and the heating resistor film 14 is set into a specific shape as required, and it becomes a gas after heating. The sensor works to provide a specific temperature.

Preferably, the thickness of the heating electrode 12 is 1um-50um, including the endpoint value, and the heating electrode 12 is selected from any of Pt, Au, Ag, Cu, Al, Ni, W, Ag/Pd, Pt/Au One kind.

As shown in FIG. 5, an embodiment of the present invention also discloses a hot wire gas sensor 20, which includes a packaging shell 200 and at least two hot wire gas sensor chips as described above arranged in the packaging shell 200. The packaging housing 200 includes a base 203, an opening 204 provided above the base 203, an explosion-proof, dust-proof and breathable membrane 201 covering the opening 204, and an electrical connector 27 provided in the base 203. Each of the hot-wire gas sensor chips is electrically connected to the base 203 through the electrical connector 27.

Further, the hot wire gas sensor 20 includes two hot wire gas sensor chips, which are a detection element chip 210 and a compensation element chip 220, respectively. The functional layer of the detection element chip 210 is a gas sensitive layer 211, and the compensation element The functional layer of the chip 220 is the environment compensation layer 221.

The packaging shell 200 not only plays a role in placing, fixing, protecting the chip and enhancing the thermal conductivity, but also serves as a bridge between the internal world of the chip and the external circuit. The heating electrodes on the detection element chip 210 and the compensation element chip 220 are respectively connected to the pins 28 of the package housing 200 by wires 27, and these pins 28 are connected to other devices through wires on the printed circuit board. Preferably, the package housing 200 may be any one of a ceramic package package, a plastic package package, and a PCB package package. The explosion-proof, dust-proof and gas-permeable membrane 201 provided on the packaging shell 200 facilitates the smooth entry of outside air into the hot wire gas sensor 20. Specifically, the explosion-proof and dust-proof breathable membrane 201 is composed of porous stainless steel powder sintered body or porous metal sheet, and has the functions of dustproof, explosion-proof and breathable. Preferably, the explosion-proof, dust-proof and breathable membrane 201 is further provided with a waterproof and breathable membrane 202. The waterproof and breathable membrane can prevent water vapor from entering the hot wire gas sensor, so as not to affect the accuracy of the sensor.

As shown in FIG. 6, it is a schematic structural diagram of a hot wire gas sensor in another embodiment of the present invention. In this embodiment, the hot-wire gas sensor 30 also includes a package housing 300, a detection element chip 36 and a compensation element chip 37. The detection chip 36 includes a silicon substrate 31 a, a heating electrode 32 a and a heating resistance film 34, and the compensation element chip includes a silicon substrate 31 b, a heating electrode 32 b and a heating resistance film 35. In this embodiment, since the thickness of the functional layer is much smaller than the thickness of the heating resistance film 34 (or heating resistance film 35), the heating resistance film 34 (or heating resistance film 35) is similar in structure to a single heating film, but in terms of function The above is still different. Specifically, the heating resistor film 34 simultaneously bears heating and gas detection functions. When there is a target gas around, the resistance value of the heating resistor film 34 will change, so that the heating resistor film 34 and the heating electrode 32a constitute a detection element. In addition, the heating resistor film 35 bears both heating and environmental compensation functions. When the target gas is around, the resistance value of the heating resistor film 35 will not change, so the heating resistor film 35 and the heating electrode 32b constitute a compensation element.

With reference to Figures 1-6, in the embodiment of the present invention, the detection principle of the hot wire gas sensor is: set the resistance of the heating resistance film of the detection element chip and the compensation element chip to R ₀ , and set the gas sensitivity of the detection element chip The resistance of the layer is set to R ₁ , and the resistance of the environmental compensation layer of the compensation element chip is set to R ₂ . According to the principle of series-parallel circuit, since the two heating resistor films and the two functional films are in parallel, the total resistance of the heating resistor film and the gas sensitive layer in the detection element chip is

The total resistance of the heating resistor film and the environmental compensation layer in the compensation element chip

The resistance value of the resistance R ₂ of the environmental compensation layer is greater than 10 MΩ, the resistance value is very large, and when there is a target gas in the environment, the resistance R _{2 of the} environmental compensation layer will not change, so the resistance R _C ≈R ₀ in the compensation element chip. The resistance R _D of the detection element chip is obtained by connecting the heating resistor R ₀ and the resistance R _{1 of the} gas-sensitive functional layer in parallel. When the target gas exists in the surrounding environment, the resistance R _{1 of the} gas-sensitive layer changes, making the resistance in the detection element chip R _D changes. Connecting the detection element chip and the compensation element chip in series to the Wheatstone bridge can detect the concentration of the target gas, and when the ambient temperature and humidity changes, the resistance of the compensation element chip and the detection element chip will change synchronously, making the electricity The bridge output signal remains stable. The hot-wire gas sensor according to the embodiment of the present invention uses a detection element chip and a compensation element chip to offset the influence of environmental temperature and humidity, and at the same time uses the parallel relationship between the gas sensitive layer and the heating resistance layer to achieve the purpose of detecting the target gas concentration. A new type of hot wire gas sensor.

In the technical solution described in the embodiment of the present invention, a predetermined metal oxide heating resistor paste is used to form a film on the surface of a silicon substrate by thick film printing technology, and then a heating resistor film with set target characteristics can be formed through high temperature sintering at a set temperature. In the same way, the set heating electrode is formed by thick film printing technology, and the heating resistance film becomes a suspension film by forming the first support portion and the second support portion. The heating electrode and heating resistor suspension film are made by high temperature sintering, and adopt thick film technology, which has good stability and reliability, and has excellent thermal insulation performance and good mechanical properties. The heating resistor film not only bears the heating function of the sensor, but also bears the support layer of the functional layer, and provides a supporting role for the functional layer. Compared with the prior art in the field, the hot-wire gas sensor in the embodiment of the present invention has no redundant heat insulation layer or support layer to support the heating resistance film, which simplifies the structure and the manufacturing process. The heating resistor film is formed by a low-cost thick film printing process, which can realize continuous automated mass production, and does not need to use expensive physical vapor deposition or chemical weather deposition equipment, which is more conducive to reducing product costs.

As shown in FIG. 7, the present invention also discloses a method for manufacturing a hot wire gas sensor, the method including:

In S1, the conductive metal oxide powder and the organic carrier are prepared into ceramic paste, which is printed or coated on the silicon substrate 11 to form the heating resistance film 14.

First, the silicon substrate 11 is a double-sided oxidized single crystal silicon substrate with 100 crystal orientations. The silicon substrate 11 needs to be ultrasonically cleaned with acetone for 10 minutes, then with isopropanol for 5 minutes, and then with deionized water for 5 minutes, and used Blow dry with nitrogen. Next, select conductive metal oxide powder of appropriate specifications, add an organic carrier, and prepare a ceramic paste, which is prepared on the silicon substrate 11 by printing or coating, and dried and sintered at a certain temperature to form a heating resistor膜14。 Film 14. Specifically, the heating resistance film with a specific pattern can be formed by any one of film forming methods such as screen printing, lithography, gravure printing, relief printing, casting, blade coating, and spray coating.

S2, printing or coating the heating electrode paste on the silicon substrate 11 to form the heating electrode 12 respectively.

The heating electrode paste is prepared on the silicon substrate 11 by printing or coating, and dried and sintered to obtain the heating electrode 12. Specifically, a heating electrode with a specific pattern can be formed by any one of film forming methods such as screen printing, lithography, gravure printing, relief printing, casting, doctor coating, and spray coating.

S3, forming an adiabatic air cavity on the silicon substrate by etching technology to obtain a micro hot plate.

The photoresist is spin-coated on the front and back of the substrate, dried on a hot stage, and the photoresist on the back of the substrate is patterned exposed and patterned. The silicon dioxide on the back is removed by reactive ion etching technology. Then, through the deep silicon etching technology, the unprotected silicon of the photoresist is etched away to form an adiabatic air cavity 13 to obtain the micro hot plate of the gas sensor.

S4, repeat the above steps S1 to S3 to make another micro hot plate.

Two micro hot plates are made to carry two different functional layers respectively.

S5, printing or coating the gas sensitive paste on one of the micro hot plates to form a gas sensitive layer.

A gas-sensitive paste is prepared and prepared on the above-mentioned micro hot plate by printing or coating to form a gas-sensitive layer. The gas sensitive layer can be formed by any one of film forming methods such as screen printing, offset printing, gravure printing, relief printing, casting, squeegee coating, and spray coating.

S6, printing or coating the environmental compensation paste on the other micro hot plate to form an environmental compensation layer.

An environment compensation paste is prepared and printed or coated on the above-mentioned another micro hot plate to form an environment compensation layer. The environmental compensation layer can be formed by any one of film forming methods such as screen printing, offset printing, gravure printing, relief printing, casting, squeegee coating, and spray coating.

S7, drying, sintering and cutting the two micro hot plates respectively to obtain the detection element chip and the compensation element chip.

In the preparation method described in the embodiment of the present invention, multiple hot-wire gas sensor chips can be prepared at the same time from a large-size wafer, and then divided into multiple single detection element chips and compensation element chips through a cutting process. Each chip has a silicon substrate 11, a heating electrode 12, a heating resistance film 14, and a functional layer 15.

S8, the detection element chip and the supplementary element chip are packaged in a packaging shell, and an explosion-proof, dust-proof and breathable membrane and a waterproof and breathable membrane are attached to the opening of the packaging shell.

Specifically, the above-mentioned drying temperature is a certain temperature between 40-200°C, and the sintering temperature is a certain temperature between 400-1200°C.

In order to better illustrate the present invention, some specific examples of the preparation method of the hot wire gas sensor are provided below.

Example 1: Provide a 4-inch monocrystalline silicon wafer with 100 crystal orientations with double-sided polishing and double-sided oxidation, and then ultrasonic cleaning with acetone for 15 minutes, then ultrasonic cleaning with isopropanol for 5 minutes, and then cleaning with deionized water for 5 minutes , And blow dry with nitrogen; select appropriate specifications of conductive metal oxide powder, add organic carrier, and prepare heating resistor film paste, and use screen printing to print a square heating resistor with a length of 300um×300um on the wafer Film and dry at 120℃ for 10min; then print the conductive paste on the wafer and dry it at 120℃ for 10min; put the dried wafer in a muffle furnace and sinter at 1000℃ 30min, get 10um thick heating resistance film and electrode electrode, and the resistance value of heating resistance film is 100Ω; spin-coated positive photoresist on the front and back of the substrate, bake it at 100℃ for 5min to cure, and pattern the photoresist on the back Chemical exposure and pattern development to obtain the unprotected area of the photoresist with a thickness of 10um and a length and width of 500um×500um. The silicon dioxide in the unprotected area is removed by reactive ion etching technology, and then deep silicon etching technology , The unprotected silicon of the photoresist is etched away to form an adiabatic air cavity to obtain a heating resistance suspension film with a first support part; the functional layer paste is prepared, and the screen printing process is used to prepare the functional layer in On the heating resistor film, bake at 150°C for 10 minutes, and sinter at 800°C for 60 minutes to obtain a gas-sensitive layer and an environmental compensation layer with a thickness of 10um, and then use laser cutting technology to obtain a detection element chip of 1.0mm×1.0mm in length and width. And the compensation component chip; the detection component chip and the compensation component chip are packaged in a ceramic tube shell, and the ceramic tube shell is mounted with an explosion-proof, dust-proof, breathable membrane and a waterproof breathable membrane to obtain a hot wire gas sensor. The obtained hot wire gas sensor The response curve is shown in Figure 8.

Example 2: Provide a double-sided polished single-product oxidized 6-inch single crystal silicon wafer with 100 crystal orientation, then ultrasonically cleaned with acetone for 10 minutes, then ultrasonically cleaned with isopropanol for 10 minutes, and then cleaned with deionized water for 5 minutes , And blow dry with nitrogen; select appropriate specifications of conductive metal oxide powder, add organic carrier, prepare heating resistance film paste, and use screen printing on the single-sided oxide layer of the wafer to print the length and width of 300um×400um Rectangular heating resistor film, and dried at 100℃ for 10min; then the conductive paste is printed on the wafer and dried at 100℃ for 10min; put the dried wafer into the muffle furnace, After sintering at 1200℃ for 20 minutes, a 20um thick heating resistor film and electrode electrodes are obtained, and the resistance value of the heating resistor film is 80Ω; the positive photoresist is spin-coated on the front and back of the substrate, and dried at 110℃ for 5 minutes to cure, and the light on the back The resist is subjected to patterned exposure and patterned development to obtain an unprotected area of the photoresist with a thickness of 8um and a length and width of 500um×500um. The silicon dioxide in the unprotected area is removed by reactive ion etching technology, and then the The silicon etching technology etches away the unprotected silicon of the photoresist to form an adiabatic air cavity to obtain a heating resistance film with a first support part, which is a suspension film structure; prepare the functional layer slurry and use them separately Screen printing process, the functional layer is prepared on the heating resistor film, dried at 120°C for 10 minutes, and sintered at 900°C for 40 minutes to obtain a gas sensitive layer and an environmental compensation layer with a thickness of 5um, and then use laser cutting technology to obtain the length and width Both are 1.0mm×1.0mm detection element chip and compensation element chip; the detection element chip and compensation element chip are packaged in a ceramic shell, and the ceramic shell is mounted with an explosion-proof, dust-proof and breathable membrane to obtain a hot wire gas sensor .

Example 3: Provide a 2-inch monocrystalline silicon wafer with 100 crystal orientations that is polished on both sides and oxidized on both sides, then ultrasonically cleaned with acetone for 10 minutes, then ultrasonically cleaned with isopropanol for 10 minutes, and then cleaned with deionized water for 5 minutes , And blow dry with nitrogen; select the appropriate specifications of conductive metal oxide powder, add organic carrier, prepare heating resistance film paste, and print a square heating resistance film with a length and width of 400um×400um on the wafer , And dry it at 150℃ for 10min; then print the conductive paste on the wafer and dry it at 150℃ for 10min; put the dried wafer in the muffle furnace and sinter it at 1100℃ for 30min , Get 15um thick heating resistor film and electrode electrode, and the resistance value of the heating resistor film is 60Ω; spin-coated positive photoresist on the front and back of the substrate, bake it at 100℃ for 5min to cure, and pattern the photoresist on the back Exposure and pattern development, to obtain the unprotected area of the photoresist with a thickness of 7um and a length and width of 600um×600um. The silicon dioxide in the unprotected area is removed by the reactive ion etching technology, and then the deep silicon etching technology is used. The unprotected silicon of the photoresist is etched away to form an adiabatic air cavity to obtain a heating resistance film with a first support part, which is a suspension film structure; the functional layer slurry is prepared and the dip coating process is used to The functional layer is prepared on the heating resistor film, baked at 150°C for 10 minutes, and sintered at 1000°C for 60 minutes to obtain a gas-sensitive layer and an environmental compensation layer with a thickness of 0.05um, and then use laser cutting technology to obtain a length and width of 1.0mm× 1.0mm detection element chip and compensation element chip; the detection element chip and the compensation element chip are packaged in a ceramic tube shell, and the ceramic tube shell is mounted with an explosion-proof, dust-proof and breathable membrane to obtain a hot wire gas sensor.

Example 4: Provide a double-sided polished and double-sided oxidized 8-inch single crystal silicon wafer with 100 crystal orientation, then ultrasonically cleaned with acetone for 10 minutes, then ultrasonically cleaned with isopropanol for 5 minutes, and then cleaned with deionized water for 5 minutes , And blow dry with nitrogen; select the appropriate specifications of conductive metal oxide powder, add organic carrier, prepare heating resistance film paste, use gravure printing to print a circular heating resistance film with a diameter of 500um on the wafer, and Dry at 120℃ for 10min; then print the conductive paste on the wafer and dry it at 120℃ for 10min; put the dried wafer in a muffle furnace and sinter it at 900℃ for 30min to obtain 25um thick heating resistor film and electrode electrodes, and the resistance value of the heating resistor film is 40Ω; spin-coated positive photoresist on the front and back of the substrate, bake it at 100°C for 5 minutes, and perform patterning exposure and patterning of the photoresist on the back Graphically developed to obtain the unprotected area of the photoresist with a thickness of 10um and a length and width of 700um×700um. The silicon dioxide in the unprotected area is removed by reactive ion etching technology, and then the light is removed by deep silicon etching technology. The unprotected silicon of the resist is etched away to form an adiabatic air cavity to obtain a heating resistance film with a first support part, which is a suspension film structure; prepare functional layer slurry, and respectively use a spraying process to prepare the functional layer On the heating resistor film, bake at 150°C for 10 minutes, and sinter at 1100°C for 15 minutes to obtain a gas-sensitive layer and an environmental compensation layer with a thickness of 1um, and then use laser cutting technology to obtain a detection element of 1.2mm×1.2mm in length and width. Chips and compensation element chips; the detection element chip and the compensation element chip are packaged in a ceramic tube shell, and the ceramic tube shell is mounted with an explosion-proof, dust-proof, breathable membrane and a waterproof breathable membrane to obtain a hot-wire gas sensor.

It should be understood that although this specification is described in accordance with the implementation manners, not each implementation manner only includes an independent technical solution. This narration in the specification is only for clarity, and those skilled in the art should regard the specification as a whole. The technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

The series of detailed descriptions listed above are only specific descriptions of feasible implementations of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementations or implementations made without departing from the technical spirit of the present invention All changes shall be included in the protection scope of the present invention.

Claims

A hot wire gas sensor chip, which is characterized in that it comprises: a silicon substrate comprising a first surface and a second surface which are arranged oppositely; the silicon substrate comprises a central heating area and a peripheral support area, and the central heating area includes a through hole The air insulation cavities on the first surface and the second surface; a heating resistor film arranged on the first surface; a heating electrode arranged on the first surface and partially covering the heating resistor film; a functional layer, provided Above the heating resistor film and located in the central heating zone, the functional layer is a gas sensitive layer or an environmental compensation layer.
4. The hot wire gas sensor chip of claim 1, wherein the functional layer is a gas sensitive layer, and the gas sensitive layer is formed by sintering a gas sensitive slurry provided on the surface of the heating resistor film.
The hot wire gas sensor chip according to claim 2, wherein the material of the gas sensitive slurry includes one or more of tin dioxide, zinc oxide, indium oxide or tungsten oxide, and a precious metal catalyst and Catalytic promoter.
The hot wire gas sensor chip according to claim 1, wherein the functional layer is an environment compensation layer, and the environment compensation layer is formed by sintering an environment compensation paste provided on the surface of the heating resistor film.
The hot wire gas sensor chip according to claim 4, wherein the material of the environmental compensation slurry includes tin dioxide, thorium dioxide, titanium dioxide, zirconium dioxide, ceria, indium oxide, lanthanum oxide, One or more of calcium oxide, barium oxide, aluminum oxide, silicon dioxide, magnesium oxide, hafnium dioxide, copper oxide, zinc oxide, and tungsten oxide.
The hot wire gas sensor chip according to claim 1, wherein the resistance of the environmental compensation layer is not less than 10MΩ.
The hot wire gas sensor chip according to claim 1, wherein the thickness of the functional layer is 0.001um to 20um.
The hot wire gas sensor chip according to claim 1, wherein the resistance value of the heating resistor film is 10Ω˜500Ω.
The hot wire gas sensor chip according to claim 1, wherein the heating electrode is formed by sintering a set metal conductive paste provided on the first surface.
The hot wire gas sensor chip according to claim 1, wherein the heating resistor film comprises at least one first supporting part, and the heating electrode comprises at least one second supporting part covering the first supporting part, The first supporting portion and the second supporting portion have the same shape, and the first supporting portion is formed by extending the portion of the heating resistor film located in the central heating area toward the peripheral supporting area, and The two supporting parts extend from the part of the heating electrode in the peripheral supporting area to the central heating area.
The hot wire gas sensor chip according to claim 10, wherein the width of the second supporting portion is less than or equal to the width of the first supporting portion.
A hot-wire gas sensor, characterized in that it comprises a packaging shell and at least two hot-wire gas sensor chips according to claim 1 arranged in the packaging shell; the packaging shell includes a base and is arranged on the base An opening above the base and an electrical connection piece arranged in the base; each of the hot-wire gas sensor chips is electrically connected to the base through the electrical connection piece.
The hot-wire gas sensor according to claim 12, wherein the hot-wire gas sensor comprises two hot-wire gas sensor chips, namely a detection element chip and a compensation element chip, and the functional layer of the detection element chip is The gas sensitive layer, the functional layer of the compensation element chip is an environmental compensation layer.
The hot-wire gas sensor according to claim 12, wherein the hot-wire gas sensor further comprises an explosion-proof, dust-proof and breathable membrane covering the opening, and the explosion-proof, dust-proof and breathable membrane is also provided with a waterproof and breathable membrane.
A method for manufacturing a hot wire gas sensor, characterized in that:

The conductive metal oxide powder and organic carrier are prepared into ceramic paste, printed or coated on the silicon substrate to form a heating resistance film;

Printing or coating the heating electrode paste on the silicon substrate to form the heating electrode;

Form an adiabatic air cavity on the silicon substrate by etching technology to obtain a micro hot plate;

Repeat the above steps to make another micro hot plate;

Printing or coating a gas sensitive paste on one of the micro hot plates to form a gas sensitive layer;

Printing or coating the environmental compensation paste on another said micro hot plate to form an environmental compensation layer;

Dry, sinter and cut the two micro hot plates respectively to obtain the detection element chip and the compensation element chip;

The detection element chip and the supplementary element chip are packaged in a tube case, and an explosion-proof, dust-proof and breathable membrane and a waterproof and breathable membrane are attached to the opening of the tube case.