阅读说明：本技术 共片加热阵列式气体检测微芯片及制备方法 (Common-chip heating array type gas detection microchip and preparation method thereof ) 是由 李娜 安飞 徐伟 孙冰 赵辰阳 冯俊杰 于 2020-04-10 设计创作，主要内容包括：本发明涉及气体传感器技术领域,公开一种共片加热阵列式气体检测微芯片及其制备方法,所述微芯片包括微加热结构和传感结构,所述微加热结构包括硅基衬底以及设置于硅基衬底的加热层,所述加热层包括加热电极；所述传感结构包括测量电极阵列以及生长于所述测量电极阵列上的至少一种气体敏感膜；所述测量电极阵列设置于所述加热层,所述测量电极阵列与所述加热电极位于同一平面,通过所述加热电极进行共片加热。本发明的测量电极阵列和加热电极设置于同一平面,通过加热电极对测量电极阵列进行共片加热,即传感结构的多个气体敏感膜均由同一加热电极进行一体化加热,实现复杂气氛检测功能,同时缩小微芯片整体的体积,降低功耗。(The invention relates to the technical field of gas sensors and discloses a common-plate heating array type gas detection microchip and a preparation method thereof, wherein the microchip comprises a micro-heating structure and a sensing structure, the micro-heating structure comprises a silicon-based substrate and a heating layer arranged on the silicon-based substrate, and the heating layer comprises a heating electrode; the sensing structure comprises a measuring electrode array and at least one gas sensitive film grown on the measuring electrode array; the measuring electrode array is arranged on the heating layer, the measuring electrode array and the heating electrode are located on the same plane, and the heating electrode is used for heating the heating layer in a sheet-sharing mode. The measuring electrode array and the heating electrode are arranged on the same plane, and the measuring electrode array is heated in a co-sheet mode through the heating electrode, namely a plurality of gas sensitive films of the sensing structure are integrally heated through the same heating electrode, so that a complex atmosphere detection function is realized, the integral volume of the microchip is reduced, and the power consumption is reduced.)

1. A common-chip heating array type gas detection microchip comprises a micro-heating structure and a sensing structure, and is characterized in that the micro-heating structure comprises a silicon-based substrate and a heating layer arranged on the silicon-based substrate, and the heating layer comprises a heating electrode;

the sensing structure comprises a measuring electrode array and at least one gas sensitive film grown on the measuring electrode array;

the measuring electrode array is arranged on the heating layer, the measuring electrode array and the heating electrode are located on the same plane, and the heating electrode is used for heating the heating layer in a sheet-sharing mode.

2. The co-planar heating array gas detection microchip of claim 1, wherein the heating electrode is distributed in the center of the heating layer and the array of measuring electrodes is distributed around the heating electrode.

3. The co-planar heating array type gas detection microchip according to claim 2, wherein the geometric length of the heating layer is preferably 1 to 6 times the geometric length of the region where the heating electrodes are distributed, and the geometric length of the heating layer is preferably 500 to 3000 μm.

4. The microchip heating array gas detection microchip according to claim 3, wherein the geometric length of the area where the heating electrodes are distributed is preferably 85 μm to 3000 μm.

5. The co-chip heating array type gas detection microchip according to claim 2, wherein the heating electrode is formed by being surrounded by a heating resistance wire, the thickness of the heating resistance wire is preferably 300nm-500nm, and the width of the heating resistance wire is preferably 10 μm-100 μm.

6. The co-chip heating array gas detection microchip as defined by claim 5, wherein the spacing between the heating resistance wires is less than twice its width.

7. The co-chip heating array type gas detection microchip according to claim 6, wherein the length of the heating resistance wire is preferably 1.5mm to 13 mm.

8. The co-chip heating array type gas detection microchip according to claim 5, wherein the measuring electrodes are of an interdigital structure, the interdigital pitch of the measuring electrodes is 1 μm to 10 μm, and the interdigital thickness of the measuring electrodes is preferably 0.2 times the interdigital pitch.

9. The co-chip heating array gas detection microchip according to claim 3, wherein the silicon-based substrate is provided at a bottom thereof with a cavity having a geometric length not greater than twice the geometric length of an area where the heating electrodes are distributed.

10. The microchip heating array gas detection microchip of claim 1, wherein the material of the heating electrode is any one of Pt, Au, Ag, W.

11. The microchip heating array gas detection microchip of claim 1, wherein the gas sensitive film is made of a gas sensitive sensing material, and the gas sensitive sensing material is WO₃、SnO₂、CuO、In₂O₃、NiO、MoO₃One or more of (a).

12. A method for preparing a co-chip heating array type gas detection microchip, comprising the steps of:

s1) providing a silicon-based substrate;

s2) manufacturing a heating electrode and a measuring electrode array on the same plane of the silicon-based substrate;

s3) growing at least one gas-sensitive film on the array of measuring electrodes.

13. The method for preparing a co-chip heating array type gas detection microchip according to claim 12, wherein the step S2) of manufacturing the heating electrode and the measuring electrode array on the same plane of the silicon-based substrate comprises:

and manufacturing a sacrificial layer on the surface of the silicon-based substrate, forming images of the heating electrode and the measuring electrode array on the surface of the silicon-based substrate through a photoetching process, and etching the heating electrode and the measuring electrode array to the sacrificial layer through an etching process.

14. The method of preparing a co-chip heating array gas detection microchip according to claim 12, further comprising:

etching a cavity at the bottom of the silicon-based substrate before step S3).

15. The method for preparing a co-chip heating array type gas detection microchip according to claim 12, wherein the step S3) of growing a gas sensitive film on the measuring electrode array comprises:

and growing a gas sensitive film on the measuring electrode array by adopting a drip integration method, a gas spray integration method, a lifting film integration method or a micro-spray lattice integration method.

16. A gas sensor comprising the co-chip heating array type gas detection microchip according to any one of claims 1 to 11.

Technical Field

The invention relates to the technical field of gas sensors, in particular to a chip-sharing heating array type gas detection microchip, a preparation method of the chip-sharing heating array type gas detection microchip and a gas sensor.

Background

With the increasing demand of people for monitoring the production process, the market demand of sensors as information acquisition terminal elements is increasing day by day. Among them, gas sensors are closely related to people's lives, and in recent years, the vigorous development of the micro-electro-mechanical processing technology provides powerful technical support for the miniaturization of sensor devices. MEMS (Micro-Electro-Mechanical System) devices use silicon as a main material, and hundreds of microelectromechanical devices can be simultaneously manufactured on one silicon wafer by micromachining, so that the production cost can be greatly reduced by mass production. The MEMS device has high integration degree, and can integrate a plurality of sensors or actuators with different functions, different sensitive directions or actuating directions into a whole, or form a micro sensor array and a micro actuator array, even integrate devices with multiple functions together to form a complex micro system. The MEMS device has the advantages of small volume, light weight, low energy consumption, short response time and the like, promotes the development of miniaturization, intellectualization, low power consumption and integration of the gas sensor, and the microstructure gas sensor is produced on the basis.

The principle of the MEMS gas-sensitive micro-heating chip is that a micro planar multi-layer heater is manufactured on a substrate material by adopting an MEMS technology, so that a semiconductor oxide sensitive material is heated to a certain temperature, the chemical activity of the semiconductor oxide sensitive material is effectively excited and reacts with target gas molecules to be detected, and the change of the conductivity of the gas-sensitive material is caused to realize the detection purpose. In the prior art, a single chip for gas-sensitive detection has single performance, a used micro-heating device mostly takes a single heating structure unit as a main part, and actually, the response of a single gas-sensitive sensor to different gases in a complex gas environment has the defect of false alarm. Because there is often more than one target object for field detection, simultaneous detection of multiple parameters and multiple targets becomes a great demand. At present, a gas sensor for detecting mixed gas generally adopts a plurality of identical micro-heating chip units to be independently arranged to form a sensor array, and the plurality of micro-heating chip units respectively heat corresponding gas-sensitive sensing materials so as to realize the detection of the mixed gas. Because each micro heating chip of the sensor array needs to be heated independently, and a plurality of micro heating chips need to be heated in a plurality of heating structures, the whole device has larger volume and higher power consumption, and the advantages of small volume and low energy consumption of the MEMS device cannot be embodied.

Disclosure of Invention

The invention aims to provide a chip-heating array type gas detection microchip and a preparation method thereof, and aims to solve the problems of large size and high power consumption of a mixed gas detection sensor.

In order to achieve the above objects, an aspect of the present invention provides a co-chip heating array type gas detection microchip comprising a micro-heating structure and a sensing structure, wherein the micro-heating structure comprises a silicon-based substrate and a heating layer disposed on the silicon-based substrate, the heating layer comprises a heating electrode;

the sensing structure comprises a measuring electrode array and at least one gas sensitive film grown on the measuring electrode array;

the measuring electrode array is arranged on the heating layer, the measuring electrode array and the heating electrode are located on the same plane, and the heating electrode is used for heating the heating layer in a sheet-sharing mode.

Furthermore, the heating electrodes are distributed in the center of the heating layer, and the measuring electrode array is distributed around the heating electrodes.

Further, the geometric length of the heating layer is preferably 1 to 6 times of the geometric length of the region where the heating electrode is distributed, and the geometric length of the heating layer is preferably 500 to 3000 μm.

Further, the geometric length of the region where the heating electrode is distributed is preferably 85 μm to 3000 μm.

Further, the heating electrode is formed by winding a heating resistance wire, the thickness of the heating resistance wire is preferably 300nm-500nm, and the width of the heating resistance wire is preferably 10 μm-100 μm.

Further, the spacing between the heating resistance wires is less than twice its width.

Further, the length of the heating resistance wire is preferably 1.5mm-13 mm.

Further, the measuring electrode is of an interdigital structure, the interdigital distance of the measuring electrode is 1-10 μm, and the interdigital thickness of the measuring electrode is preferably 0.2 times of the interdigital distance.

Further, a cavity is arranged at the bottom of the silicon-based substrate, and the geometric length of the cavity is not more than twice of the geometric length of the region where the heating electrode is distributed.

Further, the material of the heating electrode is any one of Pt, Au, Ag and W.

Further, the gas sensitive film is made of a gas sensitive sensing material, and the gas sensitive sensing material is WO₃、SnO₂、CuO、In₂O₃、NiO、MoO₃One or more of (a).

According to the common-chip heating array type gas detection microchip provided by the invention, the measuring electrode array and the heating electrode are arranged on the same plane, and the measuring electrode array is heated in a common-chip manner through the heating electrode, namely, a plurality of gas sensitive films of the sensing structure are integrally heated by the same heating electrode, so that the mixed gas detection function is realized, the integral volume of the microchip is reduced, and the power consumption is reduced.

In another aspect, the present invention provides a method for preparing a co-chip heating array type gas detection microchip, comprising the steps of:

s1) providing a silicon-based substrate;

s2) manufacturing a heating electrode and a measuring electrode array on the same plane of the silicon-based substrate;

s3) growing at least one gas-sensitive film on the array of measuring electrodes.

Further, step S2) of fabricating the heating electrode and the measuring electrode array on the same plane of the silicon-based substrate includes:

and manufacturing a sacrificial layer on the surface of the silicon-based substrate, forming images of the heating electrode and the measuring electrode array on the surface of the silicon-based substrate through a photoetching process, and etching the heating electrode and the measuring electrode array to the sacrificial layer through an etching process.

Further, before the step S3) growing the gas sensitive film on the measuring electrode array, the method further includes:

s21) etching the bottom of the silicon-based substrate to form a cavity.

Further, step S3) of growing a gas sensitive film on the measuring electrode array includes:

and growing a gas sensitive film on the measuring electrode array by adopting a drip integration method, a gas spray integration method, a lifting film integration method or a micro-spray lattice integration method.

The invention also provides a gas sensor which comprises the common-chip heating array type gas detection microchip.

According to the preparation method of the co-chip heating array type gas detection microchip, the heating electrode and the measuring electrode array are deposited on the same plane of the same silicon-based substrate, so that integrated heating of various gas-sensitive sensing materials is realized, the space utilization rate of the microchip is improved, the size is reduced, and the power consumption is reduced. On the other hand, the heating electrode and the measuring electrode array are positioned at the same plane height, and are single-layer metal systems, an insulating layer does not need to be manufactured between the heating electrode and the measuring electrode, the production process is simplified, and the manufacturing cost is reduced.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the embodiments of the invention without limiting the embodiments of the invention. In the drawings:

FIG. 1 is a schematic diagram of a microchip heating array gas detection array according to an embodiment of the present invention;

FIG. 2 is a schematic view of a heating layer of a co-chip heating array type gas detection microchip according to an embodiment of the present invention;

FIG. 3 is a schematic view of the geometric parameters of a micro-heating structure according to an embodiment of the present invention;

FIG. 4 is a graph of the ratio m/h of the geometric length of the heating layer to the geometric length of the region where the heating electrode is disposed, as a function of power, according to an embodiment of the present invention;

FIG. 5 is a graph of the ratio m/h of the geometric length of the heating layer to the geometric length of the region where the heating electrodes are disposed, as a function of thermal uniformity, according to an embodiment of the present invention;

FIGS. 6 and 7 are schematic views showing the layout of the heater layer of the co-chip heating array type gas detection microchip according to the second embodiment of the present invention;

FIG. 8 is a schematic view showing the layout of a heater layer of the co-chip heating array type gas detection microchip provided in the third embodiment of the present invention;

FIG. 9 is a flowchart of a method for manufacturing a co-chip heating array type gas detection microchip according to the fourth embodiment of the present invention;

fig. 10 and 11 are graphs showing temperature field simulations of a co-chip heating array type gas detection microchip according to an embodiment of the present invention.

Description of the reference numerals

10-silicon substrate, 11-supporting layer, 12-film layer, 13-cavity,

20-a heating layer, 21-a heating electrode, 22-a measuring electrode,

23-heating electrode pads, 24-measuring electrode pads, 30-sensing structures.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

FIG. 1 is a schematic diagram of a microchip for gas detection in a co-chip heating array according to an embodiment of the present invention. As shown in fig. 1, the common plate heating array type gas detection microchip provided by the embodiment of the present invention comprises a micro heating structure and a sensing structure 30, wherein the micro heating structure comprises a silicon-based substrate 10 and a heating layer 20 arranged on the silicon-based substrate, and the heating layer 20 comprises a heating electrode; the sensing structure 30 comprises an array of measuring electrodes and at least one gas sensitive membrane grown on the array of measuring electrodes; the measuring electrode array is arranged on the heating layer 20, and the measuring electrode array and the heating electrode are located on the same plane and are heated in a sheet-by-sheet mode through the heating electrode. Optionally, the material of the heating electrode is any one of Pt, Au, Ag and W; the gas sensitive film is made of a gas sensitive sensing material, and the gas sensitive sensing material is one or more of WO3, SnO2, CuO, In2O3, NiO and MoO 3.

When a sufficient voltage is applied across the heating electrodes, the sensing structure 30 is heated due to the high temperature reached by the joule heat. In order to realize the geometric optimization of the heating electrode and the measuring electrode array, a central heating type or cladding type geometric layout can be designed. A cavity 13 is provided at the bottom of the silicon-based substrate 10, and the cavity is designed to facilitate temperature maintenance of the micro-heating structure.

Example one

FIG. 2 is a schematic structural diagram of a heating layer of a co-chip heating array type gas detection microchip according to an embodiment of the present invention. As shown in fig. 2, in the microchip heating array gas detection provided by the first embodiment of the present invention, the heating electrode 21 is distributed at the center of the heating layer 20, and the measuring electrode array is distributed around the heating electrode 21. The measuring electrode array comprises 4 pairs of measuring electrodes 22, the heating electrodes 21 and the measuring electrodes 22 are arranged on the same plane of the silicon-based substrate 10, the 4 pairs of measuring electrodes 22 are all adjacent to the heating electrodes 21, and the 4 pairs of measuring electrodes 22 are heated in a co-sheet mode through the heating electrodes 21. The surface of the silicon substrate 10 is provided with a pair of heating electrode pads 23 and 4 pairs of measuring electrode pads 24, two ends of the heating electrode 21 are led out to the heating electrode pads 23, and the measuring electrodes 22 are respectively led out to the corresponding measuring electrode pads 24.

As shown in fig. 3, m denotes a geometric length of the heating layer, h denotes a geometric length of a region where the heating electrode is distributed, and C denotes a geometric length of the cavity of the silicon-based substrate. As shown in fig. 4, the geometric length m of the heating layer is 1 to 6 times the geometric length h of the region where the heating electrode is distributed. The geometric length m of the heating layer is 500-3000 μm, and the geometric length h of the distribution region of the heating electrode 21 is 85-3000 μm. The relationship between m/h and power consumption is shown in FIG. 4. The layout of the heating electrodes and the measuring electrodes is related to the thermal uniformity, as shown in fig. 5, as m/h increases, the temperature gradient per micron from the temperature center (heating electrode) to the edge of the heating layer changes less, although the power and uniformity are better with a larger ratio, it is not advisable to increase the range of m/h any more from the viewpoint of processing and economic efficiency.

The cavity 13 of the silicon-based substrate 10 is beneficial to the heating layer 20 with the heating electrode 21 arranged at the center to reach higher working temperature, the geometric length C of the cavity 13 is not more than twice of the geometric length h of the area where the heating electrode 21 is distributed, namely C/h is more than or equal to 0 and less than or equal to 2, and when the ratio of C/h is maximum, the temperature of the heating layer 20 can reach stable 700 ℃. The geometric length h of the distribution area of the heating electrode 21 is 85-3000 μm, and the geometric length C of the cavity 13 is preferably 50-6000 μm. The measuring electrode 22 is an interdigital structure (e.g., a finger-shaped or comb-shaped electrode structure), and the distance between the fingers of the measuring electrode is 1 μm to 10 μm. The layout of the measuring electrodes 22 is related to the thermal uniformity, the temperature gradient change per micron from the temperature center to the edge of the heating layer is smaller as the m/h is increased, the number of the measuring electrodes, the interdigital length, the interdigital thickness, the interdigital distance (or the distance between the interdigital electrodes on the same side) of the measuring electrodes and the thickness of the gas sensitive film are designed according to the number of the adopted gas sensitive sensing materials. The length of the interdigital of the measuring electrode depends on the length m of the geometric shape of the heating layer and the number of the measuring electrodes, and the effect of heating by a plurality of measuring electrodes in a common plate is best when the thickness of the interdigital of the measuring electrode is 0.2 times of the interdigital distance.

The heating electrode 21 is formed by winding a heating resistance wire, the thickness t of the heating resistance wire is 300nm-500nm, and the width w of the heating resistance wire is 10 mu m-100 mu m. The distance d between the heating resistance wires is less than twice of the width w of the heating resistance wires, namely d is less than 2 w. Since the required heating temperature of the gas-sensitive sensing material can reach 700 ℃, the resistance R of the micro-heating structure is usually between 90 Ω -200 Ω, and the resistance formula R ═ ρ · L/S ═ ρ · L/(w · t), where ρ denotes the resistivity (known) of the heating resistance wire, L denotes the length of the heating resistance wire, S denotes the cross-sectional area of the heating resistance wire (S ═ w · t), w denotes the width of the heating resistance wire, and t denotes the thickness of the heating resistance wire. The length range of the heating resistance wire L is 1.5mm-13mm according to the resistance formula. The heating resistance wire encircles and forms the heating electrode, and the round-off corner of the heating resistance wire is set to be the internal fillet shape. Because the corner is the right angle or acute angle structure, its local electric current gathers, can lead to the effective resistance increase of heating electrode to arouse the temperature rise phenomenon, makes the temperature of heating electrode inhomogeneous, consequently, when the corner of heating resistor silk is fillet shape, its electron gathers the phenomenon weak, can avoid local high temperature.

The micro-heating structure provided by the embodiment is suitable for gas-sensitive sensing materials with the working temperature range of 100-700 ℃, such as WO3, SnO2, CuO, In2O3, NiO and MoO 3; when the sensing structure is coated with one gas-sensitive sensing material or a plurality of gas-sensitive sensing materials with smaller working temperature difference (within 30 ℃), the micro-heating structure has the best heating effect on the sensing structure, the sensing structure generates good response, and the detection result is more accurate. For example, the optimum operating temperature for detecting hydrogen sulfide gas by using the WO3 nanowire is 350 ℃, the optimum operating temperature for detecting CO by using the flower-shaped SnO2 is also 350 ℃, and if the single power consumption of the conventional micro heating plate is 50mW to 200mW, the power consumption of the micro heating structure and the sensing structure provided by the embodiment is 22mW to 100mW (refer to fig. 4), which is much lower than that of the conventional micro heating plate. For example, when the sensing structure is provided with 4 sets of measuring electrodes (for detecting 4 gases), the geometric length m of the heating layer is 500 μm to 3000 μm, while the geometric length of the conventional micro-heating plate is 1000 μm to 3000 μm, the length of the 4 micro-heating plates is 4000 μm at the minimum, and the size of the micro-heating structure of the embodiment is 500 μm at the minimum, which is much smaller than that of the conventional micro-heating plate array.

Example two

Fig. 6 and 7 are schematic views showing the layout of the heating layer of the co-chip heating array type gas detection microchip according to the second embodiment of the present invention. Different from the first embodiment, in the second embodiment, a pair of heating electrodes 21 and six pairs of measuring electrodes 22 (which may correspond to six different gas sensitive sensing materials) are arranged in the heating layer, two ends of the heating electrodes 21 are led out to the heating electrode pads 23, and the six pairs of measuring electrodes 22 are arranged in an array. As shown in fig. 6, the heating electrodes 21 are distributed at the outer edge of the array of measuring electrodes 22. As shown in fig. 7, the heating electrodes 21 are distributed in the central region of the array of measuring electrodes 22. In this embodiment, the heating electrodes 21 are symmetrically distributed in the central area or the outer edge of the measuring electrode 22, so as to ensure that the planar measuring area is heated uniformly, thereby achieving the effect of stable and uniform temperature control of the device.

EXAMPLE III

FIG. 8 is a schematic view of the layout of the heating layer of the co-chip heating array type gas detection microchip according to the third embodiment of the present invention. Different from the first embodiment, in the third embodiment, a pair of heating electrodes 21 and three pairs of measuring electrodes 22 (which may correspond to three different gas sensitive sensing materials) are arranged in the heating layer, two ends of the heating electrodes 21 are led out to the heating electrode pads 23, the three pairs of measuring electrodes 22 are arranged in a T shape, and the heating electrodes 21 are distributed at the outer edges of the three pairs of measuring electrodes 22. In addition, according to different types of gases to be detected, the number of the measuring electrode arrays can be correspondingly increased or decreased, and in order to keep the temperature caused by the heating electrodes constant and keep the external potential constant, the geometric layout coordinates of the heating wires forming the heating electrodes can be correspondingly adjusted according to the number of the measuring electrodes.

The heating layer of the common-plate heating array type gas detection microchip provided by the first embodiment to the third embodiment of the invention comprises a measuring electrode array consisting of a pair of heating electrodes and a plurality of pairs of measuring electrodes 22, the measuring electrode array is heated in a common-plate mode through the pair of heating electrodes 21, the measuring electrode array and the heating electrodes 21 are arranged on the same plane, and the measuring electrode array is heated in a common-plate mode through the heating electrodes 21, namely, a plurality of gas sensitive films of the sensing structure 30 are integrally heated through the same heating electrode 21, so that the mixed gas detection function is realized, the integral volume of the microchip is reduced, and the power consumption is reduced.

In addition, since the heating electrode pads 23 and the measuring electrode pads 24 need to be welded to the integrated circuit leads in the microchip packaging process, the microchip needs to be connected to the housing through manual bonding wires in the housing packaging process, and if there are n micro-heating structures, 2n × n heating electrode wires need to be bonded manually. The microchip of the embodiment of the invention adopts the common-chip heating, only one group of heating current needs to be provided, and only 2 heating electrode leads need to be bonded manually during packaging, thereby greatly reducing the manual operation difficulty and simplifying the packaging process.

Example four

FIG. 9 is a flowchart of a method for manufacturing a microchip for heating array gas detection according to the fourth embodiment of the present invention. Referring to fig. 1 and 9, in an embodiment of the present invention, a method of manufacturing a co-chip heating array type gas detection microchip includes:

s1) providing a silicon-based substrate.

The Silicon-based substrate 10 adopts an SOI wafer layer with p-type boron-doped Silicon (Si), and an SOI (Silicon-On-Insulator, i.e. Silicon On an insulating substrate) Silicon wafer means that a buried oxide layer (BOX) is introduced between top Silicon and a backing substrate to be used as a supporting layer 11, and a Silicon oxide or Silicon nitride film layer 12 with the thickness of not more than 1 μm is coated On the front surface and the back surface of the Silicon wafer by adopting a plasma enhanced chemical vapor deposition method.

S2) manufacturing a heating electrode and a measuring electrode array on the same plane of the silicon-based substrate.

And manufacturing a sacrificial layer on the surface of the silicon-based substrate, forming images of the heating electrode and the measuring electrode array on the surface of the silicon-based substrate through a photoetching process, and etching the heating electrode and the measuring electrode array to the sacrificial layer through an etching process.

In this step, a heater wire as a heating electrode, a measuring electrode, a lead wire, and an electrode pad are formed by a method of photolithography followed by evaporation. The method specifically comprises the following steps: rotationally coating a thin photoresist film on the surface of a silicon wafer, partially evaporating a photoresist solvent by heating, and accurately aligning by using a pre-customized mask plate; and exposing a specified area on the photoresist by adopting an ultraviolet lithography technology, and performing heating layer metal evaporation with the thickness of 100-500nm on the exposed surface of the photoresist in a vacuum evaporation way, and ensuring that the heating electrode is provided with a positive electrode lead bonding pad and a negative electrode lead bonding pad. And putting the evaporated silicon wafer into an acetone solution to be soaked for 4-5 hours to dissolve the photoresist and wash away the redundant evaporated metal to form a heating layer structure. And finally, taking the silicon wafer out of the acetone solution, washing the silicon wafer clean by deionized water, and drying the silicon wafer by high-purity nitrogen.

And after the heating electrode and the measuring electrode are manufactured, etching the bottom of the silicon-based substrate to form a cavity 13 structure, so that the heating electrode and the measuring electrode form a suspension structure. The method specifically comprises the following steps: the backside structuring using photolithography is used in conjunction with Reactive Ion Etching (RIE) to remove the exposed silicon nitride layer on the backside of the silicon wafer and etch deep into the silicon wafer, with potassium hydroxide (KOH) for crystal orientation by anisotropic electrochemical wet etching down to the support layer embedded in the silicon-based substrate. After the back surface of the silicon wafer is coated with photoresist, a specific mask plate is selected and used for exposing the areas corresponding to the heating electrode and the measuring electrode on the back surface and the front surface of the silicon wafer by using an ultraviolet photoetching machine, then the areas are developed and fixed, the substrate silicon in the window is etched, and the heating electrode and the measuring electrode are partially suspended to form a cavity 13 structure shown in figure 1.

S3) growing at least one gas-sensitive film on the array of measuring electrodes.

Wherein, a gas sensitive film is grown on the measuring electrode array by adopting a drip integration method, a gas spray integration method, a lifting film integration method or a micro-spray lattice integration method. In order to detect more than two gases simultaneously, a gas sensitive film is made of a nano gas sensitive sensing material which responds to gas signals specifically or In a broad spectrum manner, the nano gas sensitive sensing material is one or a combination of more of WO3, SnO2, CuO, In2O3, NiO and MoO3 metal oxide materials, and the thickness of the gas sensitive film is 10nm-2 mu m. Different gas sensitive films grow on different measuring electrodes, and mixed gas detection can be realized.

For example, since the optimal working temperature of WO3 and flower-shaped SnO2 is 350 ℃, WO3 nanowire gas sensitive films are grown on one pair of measuring electrodes, and flower-shaped SnO2 gas sensitive films are grown on the other pair of measuring electrodes, so that hydrogen sulfide and carbon monoxide can be detected and identified respectively. The heating resistance wire is a Pt resistance wire, the wire width w is 35 mu m, the thickness t is 300nm, the length L of the heating resistance wire is 2.5mm, the resistance is 114.3 omega, the geometric length h of a distributed area of the heating electrode is 250 mu m, and the geometric length m of the heating layer ranges from 500 mu m to 3000 mu m. The position of the measuring electrode can be designed according to the detection requirement in the area not covered by the heating electrode, and the gas sensor is prepared by depositing the gas-sensitive sensing material on the measuring electrode.

For example, when the gas-sensitive sensing material adopts a molybdenum trioxide MoO3 nano material with a core-shell structure and an optimal working temperature of 650-700 ℃, a Pt resistance wire is adopted as the heating resistance wire, the wire width w is 70 μm, the thickness t is 300nm, the length L of the heating resistance wire is 8mm, the resistance is 181.5 Ω, the geometric length h of a distributed area of the heating electrode is 950 μm, the geometric length m of the heating layer can be selected within a range of 950 μm-3000 μm, and the geometric length C of the cavity is 1900 μm, so as to meet the high temperature requirement. And designing the position of the measuring electrode in the area not covered by the heating electrode according to the detection requirement, and depositing the gas-sensitive material on the measuring electrode to finish the preparation of the gas sensor. For example, the resistance value of the heating electrode is calculated according to a specific temperature, and the length, thickness or width of the heating resistance wire is calculated according to a resistance formula, which is specifically referred to in the first embodiment.

Fig. 10 and 11 are simulation diagrams of temperature fields of the co-chip heating array type gas detection microchip according to the embodiment of the present invention. The simulation conditions of the temperature field simulation diagram shown in fig. 10 are as follows: the geometric length m of the heating layer is 500 mu m, the geometric length h of the region where the heating electrodes are distributed is 245 mu m, the m/h of the heating electrode is 500 mu m/245 mu m of the heating electrode is 2, the line width w of the heating resistance wire is 20 mu m, the distance d of the heating resistance wire is 50 mu m, and the thickness t of the heating resistance wire is 300 nm. The simulation results are: the maximum heating temperature is 610.72 ℃, and the power is 48 mW. The simulation conditions of the temperature field simulation diagram shown in fig. 11 are as follows: the geometric length m of the heating layer is 1000 μm, the geometric length C of the cavity is 660 μm, m/C is 1000 μm/660 μm is 1.51, the line width w of the heating resistance wire is 10 μm, the distance d of the heating resistance wire is 40 μm, and the thickness t of the heating resistance wire is 300 nm. The simulation results are: the maximum heating temperature is 741.5 ℃, and the power is 20 mW.

According to the preparation method of the co-chip heating array type gas detection microchip, the heating electrode and the measuring electrode array are deposited on the same plane of the same silicon-based substrate, so that integrated heating of various gas-sensitive sensing materials is realized, the space utilization rate of the microchip is improved, the size is reduced, and the power consumption is reduced. On the other hand, the heating electrode and the measuring electrode array are positioned at the same plane height, and are single-layer metal systems, an insulating layer does not need to be manufactured between the heating electrode and the measuring electrode, the production process is simplified, and the manufacturing cost is reduced.

The embodiment of the invention also provides a gas sensor which comprises the common-chip heating array type gas detection microchip or a microchip manufactured by adopting the preparation method of the common-chip heating array type gas detection microchip.

While the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the embodiments of the present invention are not limited to the details of the above embodiments, and various simple modifications can be made to the technical solution of the embodiments of the present invention within the technical idea of the embodiments of the present invention, and the simple modifications are within the scope of the embodiments of the present invention. The various features described in the foregoing detailed description may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, the embodiments of the present invention will not be described separately for the various possible combinations.