CN117147635A - A silicon-based MEMS gas sensor, array and preparation method - Google Patents

Abstract

The application discloses a silicon-based MEMS gas sensor, an array and a preparation method. The silicon-based MEMS gas sensor comprises: a silicon wafer substrate, a detection region and a control electrode region; the detection area comprises 4 gas-sensitive detection areas; the control electrode area comprises 4 independent heating electrode pins, 4 independent test electrode pins, 2 common heating electrode pins and 2 common test electrode pins; one end of the heating electrode of the gas-sensitive detection area is connected with the pin of the independent heating electrode, and the other end of the heating electrode of the gas-sensitive detection area adjacent to the heating electrode in the vertical direction is connected with the pin of the common heating electrode; the test electrode of the gas-sensitive detection area comprises an independent test electrode and a common test sub-electrode, and the independent test electrode is connected with an independent test electrode pin; each gas-sensitive detection area is used for carrying out independent temperature control and independent gas-sensitive detection through an independent heating electrode pin and a test electrode pin. The whole area and structure of the sensor array chip are optimized, the integration level is highest, and the area is minimum.

Description

Silicon-based MEMS gas sensor, array and preparation method

Technical Field

The application belongs to the field of gas detection sensors, and particularly relates to a silicon-based MEMS gas sensor, an array and a preparation method.

Background

MEMS metal oxide semiconductor sensors have been widely used in various fields of gas detection in recent years due to their high detection sensitivity, easiness in detection, low power consumption, and low cost. With the rapid development of internet of things (IoT) and Artificial Intelligence (AI), gas identification is an important application field of gas sensors, and intelligent identification of gas types requires multiple types of MEMS metal oxide semiconductor sensors to acquire sensing information at the same time.

Most of the current intelligent gas detection realizes the acquisition of diversified sensing information through the board-level array of the sensor, and the MEMS metal oxide semiconductor sensor array chip can realize the simultaneous detection of various gas-sensitive materials on target gas by integrating a plurality of sensor detection film areas on a single micro heating plate.

However, in the existing MEMS gas sensor, after the heating electrode and the detecting electrode of each gas detecting component are connected in series, the heating electrode and the detecting electrode are controlled by a pair of heating electrodes and detecting electrodes, so that independent temperature control and test cannot be performed; if each gas detection component is configured with an independent heating electrode and a test electrode, the number of the integrated gas detection components is limited due to the limitation of the chip size, so that the information acquisition amount of a single gas sensor is limited, and the requirement of diversified information acquisition cannot be met.

Disclosure of Invention

Aiming at the defects of the related technology, the application aims to provide a silicon-based MEMS gas sensor, an array and a preparation method, and aims to solve the problems that intelligent gas identification in the gas detection field cannot be independently tested and the requirement for acquiring diversified information is difficult to meet.

To achieve the above object, in a first aspect, the present application provides a silicon-based MEMS gas sensor, comprising: a silicon wafer substrate, a detection area arranged above the corrosion cavity of the silicon wafer substrate, and a control electrode area arranged around the corrosion cavity;

the detection areas comprise 4 gas-sensitive detection areas which are arranged in a shape of Chinese character 'tian'; the control electrode area comprises 4 independent heating electrode pins, 4 independent test electrode pins, 2 common heating electrode pins and 2 common test electrode pins;

the heating electrode layer of the gas-sensitive detection area comprises a heating electrode, and the testing electrode layer comprises two testing electrodes; one end of the heating electrode is connected with the independent heating electrode pin, and the other end of the heating electrode is connected with the heating electrode of the gas-sensitive detection area adjacent to the vertical direction and is commonly connected with a common heating electrode pin;

the gas sensitive material film of the gas sensitive detection area is laid on the two test electrodes in a flat way; the test electrode comprises an independent test electrode and a common test sub-electrode, and forms an interdigital electrode; the four common test sub-electrodes form a complete common test electrode; the independent test electrode is connected with the independent test electrode pin, and two ends of the common test electrode are connected with the common test electrode pin;

and independently controlling the temperature of each gas-sensitive detection area through an independent heating electrode pin, and independently detecting the gas-sensitive detection areas through independent testing electrode pins.

Optionally, the heating electrode is strip-shaped and uniformly meanders in the heating electrode layer of the gas-sensitive detection area.

Optionally, the corrosion cavity is located at the center of the silicon wafer substrate, the cantilever supporting layer of the gas-sensitive detection area comprises cantilever beams, cantilever beams are respectively arranged on symmetry axes of the gas-sensitive detection area in the horizontal direction and the vertical direction, and 4 cantilever beams of the detection area are supported above the cavity of the silicon wafer substrate together to form a suspended structure.

In a second aspect, the present application also provides a silicon-based MEMS gas sensor array comprising a plurality of silicon-based MEMS gas sensors as claimed in any one of the first aspects.

In a third aspect, the present application also provides a method for preparing a silicon-based MEMS gas sensor as described in any of the first aspects, comprising the steps of: the method comprises the following steps:

s1, depositing an insulating material on the surface of a silicon wafer substrate at a wafer level to form a cantilever supporting layer covered on the silicon wafer substrate;

s2, depositing metal on the cantilever support layer at the wafer level, forming a heating electrode in the detection area, and forming a heating electrode pin in the control electrode area; the detection areas comprise 4 gas-sensitive detection areas which are arranged in a shape of Chinese character 'tian'; the control electrode zone comprises 4 independent heating electrode pins and 2 common heating electrode pins; one end of the heating electrode of the gas-sensitive detection area is connected with an independent heating electrode pin, and the other end of the heating electrode of the gas-sensitive detection area adjacent to the heating electrode in the vertical direction is connected with the heating electrode pin and is commonly connected with a common heating electrode pin;

s3, depositing an insulating material on the surface of the heating electrode at a wafer level to form an insulating layer covering the cantilever supporting layer and the heating electrode;

s4, depositing metal on the insulating layer at the wafer level, forming a test electrode in the detection area, and forming a test electrode in the control electrode area; the control electrode region comprises 4 independent test electrode pins and 2 common test electrode pins; the test electrode comprises an independent test electrode and a common test sub-electrode, and forms an interdigital electrode; the four common test sub-electrodes form a complete common test electrode; the method comprises the steps of carrying out a first treatment on the surface of the The independent test electrode is connected with the independent test electrode pin, and two ends of the common test electrode are connected with the common test electrode pin;

s5, forming etching windows above each independent heating electrode pin and each common heating electrode pin, wherein the etching windows penetrate through the insulating layer to expose the upper surfaces of the independent heating electrode pins and the common heating electrode pins;

s6, forming corrosion windows around the gas-sensitive detection area, wherein the corrosion windows penetrate through the insulating layer and the cantilever support layer;

s7, forming a gas-sensitive material film on each gas-sensitive detection area through deposition and sputtering; the gas-sensitive material film is laid on the two test electrodes in a flat way;

and S8, carrying out a dicing process on the silicon-based MEMS gas sensor array prepared at the wafer level to obtain a single silicon-based MEMS gas sensor.

Optionally, the cantilever support layer is made of an ONO composite material; wherein the thickness of the first layer of silicon oxide ranges from 100nm to 200nm, the thickness of the second layer of silicon nitride ranges from 300nm to 700nm, and the thickness of the third layer of silicon oxide ranges from 500nm to 1100nm.

Optionally, the heating electrode is a uniformly meandering metal electrode;

the insulating layer material is silicon oxide or silicon nitride or a mixed material of the silicon oxide and the silicon nitride;

the test electrode comprises an independent test electrode and a common test sub-electrode to form an interdigital electrode; the four common test sub-electrodes form a complete common test electrode;

the etching solution adopted by the etching window is tetramethyl ammonium hydroxide, so that an etching cavity is formed below the gas-sensitive material film, and only the gas-sensitive detection area and the cantilever beam carrying the electrode are reserved;

the gas-sensitive material film is made of metal oxide semiconductor material, and the thickness range is 100nm-800nm.

Compared with the prior art, the technical scheme of the application has the following beneficial effects:

1. the application provides a silicon-based MEMS gas sensor, which comprises a plurality of gas-sensitive detection areas, wherein the gas-sensitive detection areas are integrated on one corrosion pit, and the plurality of gas-sensitive detection areas are fixed by a plurality of cantilever beams, so that the silicon-based MEMS gas sensor has high space utilization rate. Because the size of the electrode pin pad often limits the whole area of the sensor array chip, the test electrodes on all the gas-sensitive detection areas comprise an independent test electrode and a common test sub-electrode to form an interdigital electrode, four common test sub-electrodes form a complete common test electrode, and the common test electrode is connected with two common test electrode pins. The reconstruction electrode connection mode for reference is provided, the integration level of the sensing unit is highest, the area is minimized, the optimization of the whole area and the structure of the sensor array chip is facilitated, the maximization convenience is provided for the subsequent wire bonding process, and the control of the manufacturing cost is remarkably improved.

2. The application provides a silicon-based MEMS gas sensor, a plurality of gas-sensitive detection areas are compactly distributed and are positioned on the same pit after wet corrosion is released, gas detection points of the sensor are more concentrated than those of the sensor integrated on a plate, gas components tend to be more consistent during detection, the reliability of a gas detection result can be improved, and guarantee is provided for reusability of a subsequent gas identification algorithm.

3. The application provides a silicon-based MEMS gas sensor, wherein a plurality of gas-sensitive detection areas are connected with serpentine heating electrodes to form independent loops, so that independent voltage input control can be realized, different working temperatures can be provided for metal oxide semiconductor gas-sensitive materials on each gas detection area, gas-sensitive detection data of the same gas-sensitive material at different temperatures can be obtained, gas-sensitive detection data of a plurality of gas-sensitive materials at the same time at the optimal working temperature can be ensured, the data quantity is enriched, and a diversified solution is provided for intelligent gas identification.

Drawings

FIG. 1 is a schematic diagram of a silicon-based MEMS gas sensor according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a test electrode for preparing a MEMS gas sensor according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a heating electrode for preparing a MEMS gas sensor according to an embodiment of the present application.

The same reference numbers are used throughout the drawings to reference like elements or structures, wherein: 1 is a silicon wafer substrate, 2 is a corrosion cavity, 3 is a detection area, 4 is a gas-sensitive detection area, 41 is a heating electrode, 42 is a test electrode, 421 is an independent test electrode, 422 is a common test sub-electrode, pad1 is an independent heating electrode pin, pad2 is a common heating electrode pin, pad3 is a common test electrode pin, and pad4 is an independent test electrode pin.

Detailed Description

The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application. In addition, the technical features of the embodiments of the present application described below may be combined with each other as long as they do not collide with each other.

The description of the contents of the above embodiment will be given below in connection with a preferred embodiment.

Example 1

As shown in fig. 1, a structure of a silicon-based MEMS gas sensor is as follows from bottom to top: the silicon wafer comprises a silicon wafer substrate, a cantilever supporting layer, a heating electrode, an insulating layer, a test electrode and a gas-sensitive film, wherein a corrosion cavity 2 is formed in the center of the silicon wafer substrate 1 to form a three-dimensional structure, a detection area 3 positioned in the center above the cavity is supported by a plurality of cantilever beams around to form a suspension structure, and a control electrode area is arranged around the corrosion cavity 2. The detection zone 3 comprises 4 gas sensitive detection zones 4, each gas sensitive detection zone 4 being provided with a uniformly meandering heating electrode 41 and a test electrode 42. The control electrode region includes 4 independent heating electrode pins, 4 independent test electrode pins, 2 common heating electrode pins pad2, and 2 common test electrode pins pad3.

As shown in fig. 3, the first end of the heating electrode 41 of each gas-sensitive detection area 4 is connected to the independent heating electrode pin pad1, and the other end is connected to the heating electrode 41 'of the gas-sensitive detection area 4' adjacent in the vertical direction and is commonly connected to one common heating electrode pin pad2;

the gas-sensitive material film is laid on the two test electrodes (421 and 422) in a flat way; the test electrodes comprise an independent test electrode 421 and a common test sub-electrode 422, the common test sub-electrode 422 of the four gas-sensitive detection areas forms a complete common test electrode, the common test electrode is fishbone-shaped, and the common test electrode and the independent test electrodes of the four gas-sensitive detection areas form interdigital electrodes respectively; the independent test electrode is connected with an independent test electrode pin pad4, and two ends of the common test electrode are connected with a common test electrode pin pad 3;

and independently controlling the temperature of each gas-sensitive detection area 4 through an independent heating electrode pin pad1, and independently detecting the gas-sensitive detection areas 4 through independent testing electrode pins pad 4.

In this embodiment, the silicon-based MEMS gas sensor includes 4 gas-sensitive detection areas, each gas-sensitive detection area 4 is rectangular, and is arranged in a shape of a Chinese character 'tian', so that a large rectangle is formed together, and the whole width of the cantilever beam can be widened by adopting a rectangular structure, so that the mechanical strength of the cantilever is improved, and the fracture risk of the cantilever is reduced. In one embodiment, as shown in fig. 1, the electrode width of the heating electrode 41 and the test electrode 42 is about 10um, and the area of the whole area of the single gas-sensitive detection area is about 110um by 110um. The silicon-based MEMS gas sensor has 4 heating electrodes 41, wherein one end of each heating electrode 41 is individually connected to an independent heating electrode pin pad1 (the area is about 150um x 150um-200um x 200 um), and the other end is connected to a heating electrode of a gas-sensitive detection area adjacent to the vertical direction and is commonly connected to a common heating electrode pin pad2.

The 4 gas-sensitive detection areas comprise a common test electrode and 4 independent test electrodes; each gas-sensitive detection zone comprises two test electrodes, wherein the test electrodes comprise an independent test electrode and a common test sub-electrode to form interdigital electrodes; the four common test sub-electrodes form a complete common test electrode, the common test electrode (the area is 240um x 20 um) is in a fishbone shape, the common test electrode horizontally passes through the centers of the four gas-sensitive detection areas and forms interdigital electrodes with the independent test electrodes of the four gas-sensitive detection areas respectively; each independent test electrode is connected with an independent test electrode pin pad4, and two ends of the common test electrode are respectively connected with two common test electrode pins. The design mode ensures that the grounding ends or the power supply ends of the heating or testing electrodes are connected together on the chip, and the connection mode can ensure that the whole structure is simplified under the condition that the independent temperature control and the independent test of each gas detection area can be realized, the integration level of the sensing unit is highest, the area is minimized, convenience is provided for the subsequent bonding process, and meanwhile, the process consistency is also improved.

The brownian motion of the gas molecules can cause uncontrollable changes of the gas components in a certain space, so that a plurality of gas sensitive detection areas are intensively arranged in the embodiment, and the high-density integration of the gas detection points is beneficial to reducing detection errors caused by the changes of the gas components.

In this embodiment, the common test electrode is a strip-shaped fishbone electrode, and the electrode width is obviously wider than the widths of the heating electrode and the test electrode, so that the resistance can be reduced, the power consumption can be reduced, and the energy efficiency of the total power consumption can be improved.

Further, as shown in fig. 2, the openings between the independent test electrode 421 and the common test sub-electrode 422 of each gas-sensitive detection area are separated to form an interdigital electrode, and the gas-sensitive material film is laid on the interdigital electrode in a flat manner.

The gas-sensitive film is prepared on the interdigital electrode, so that the surface of the gas-sensitive film is fully contacted with the electrode, the electrode can rapidly detect the resistance change of the gas-sensitive film, and the accuracy and the sensitivity of gas-sensitive detection are improved.

Optionally, the corrosion cavity is located at the center of the silicon wafer substrate, the cantilever supporting layer of the gas-sensitive detection area comprises cantilever beams, cantilever beams are respectively arranged on symmetry axes of the gas-sensitive detection area in the horizontal direction and the vertical direction, and the detection area is supported above the cavity of the silicon wafer substrate by 4 cantilever beams together to form a suspended structure.

The scheme is characterized in that a plurality of gas-sensitive detection areas are intensively designed on one corrosion cavity, 4 gas-sensitive detection areas are distributed in a limited space to form a silicon-based MEMS gas sensor array, compared with the simple arrangement of a plurality of traditional MEMS gas sensors, the scheme realizes the sensor array, has higher integration level, reduces the whole area of the gas sensor array, and in gas-sensitive detection, due to the uncertain movement of gas molecules, the gas components contacted during detection of the gas-sensitive detection areas with a shorter distance are more similar, and the gas detection result has higher reliability.

Further, on the basis of the above embodiment, the embodiment of the present application further provides a silicon-based MEMS gas sensor array, where the silicon-based MEMS gas sensor array includes a plurality of the gas sensors described in the above embodiment.

In the embodiment of the application, the heating electrodes on all the gas-sensitive detection areas are connected in pairs and are commonly connected to one common heating electrode pin, so that the number of the heating electrode pins is reduced; the test electrodes on all the gas-sensitive detection areas comprise an independent test electrode and a common test sub-electrode to form an interdigital electrode, the four common test sub-electrodes form a complete common test electrode, the common test electrode is connected with two common test electrode pins, the electrode connection mode is reconstructed, and the whole area and structure of the sensor array chip are optimized. The integration level of the sensing unit is highest, the area is minimized, and the control method has remarkable advantages in control of manufacturing cost; each gas-sensitive detection area is provided with an independent test electrode and an independent heating electrode, so that each gas-sensitive detection area can be controlled to independently detect gas; the gas sensitive detection regions are positioned on the same pit after being released by wet corrosion, are compactly distributed, and gas components tend to be more consistent during detection, so that the reliability of gas detection results can be improved, and the guarantee is provided for the reusability of a subsequent gas identification algorithm.

Example 2

A preparation method of a silicon-based MEMS gas sensor comprises the following steps:

s1, depositing an insulating material on the surface of a silicon wafer substrate at a wafer level to form a cantilever supporting layer covered on the silicon wafer substrate;

specifically, an ONO composite film is deposited on a silicon wafer substrate, firstly a silicon oxide layer is prepared through thermal oxidation, secondly a silicon nitride layer is prepared through LPCVD, the silicon oxide layer is prepared through LPCVD, and through the advantages of high mechanical strength of silicon nitride and low heat conductivity coefficient of silicon oxide, three layers of materials can be combined and matched according to a proper thickness proportion, so that good effects of low stress and strain of a cantilever structure and high peak temperature of heating resistance can be achieved, and the thicknesses of the three layers of materials are preferably 200nm, 500nm and 1100nm.

S2, depositing metal on the cantilever support layer at the wafer level, forming a heating electrode in the detection area, and forming a heating electrode pin in the control electrode area; the detection zone 2 comprises 4 gas-sensitive detection zones 4, and the control electrode zone comprises 4 independent heating electrode pins pad1 and 2 common heating electrode pins pad2; one end of the heating electrode 41 of the gas-sensitive detection area 4 is connected with the independent heating electrode pin pad1, and the other end is connected with the heating electrode 41 'of the gas-sensitive detection area 4' adjacent to the heating electrode pin pad1 in the vertical direction and is commonly connected with one common heating electrode pin pad2. As shown in fig. 3.

Specifically, sputtering of the titanium-platinum metal of the heating electrode is performed on the cantilever support layer using a lift-off process or a metal etching process in combination with a photolithography process, and the thickness is about 150nm.

S3, depositing an insulating material on the surface of the heating electrode at the wafer level to form an insulating layer covering the cantilever supporting layer and the heating electrode.

Specifically, silicon oxide or silicon nitride or a mixture of both insulating materials are deposited over the heater electrode using a PECVD or LPCVD process to a thickness of about 500nm.

S4, depositing metal on the insulating layer at the wafer level, forming a test electrode in the detection area, and forming a test electrode in the control electrode area; the control electrode region comprises 4 independent test electrode pins and 2 common test electrode pins; the test electrode comprises an independent test electrode and a common test sub-electrode, the common test sub-electrode of the four gas-sensitive detection areas forms a complete common test electrode, the common test electrode is fishbone-shaped, and the common test electrode and the independent test electrodes of the four gas-sensitive detection areas form interdigital electrodes respectively; the independent test electrode is connected with the independent test electrode pin, and two ends of the common test electrode are connected with the common test electrode pin.

Specifically, sputtering of test electrode titanium-platinum metal is performed on the insulating layer using a lift-off process or metal etching in combination with a photolithography process, to a thickness of about 150nm.

S5, forming etching windows above each independent heating electrode pin and each common heating electrode pin, wherein the etching windows penetrate through the insulating layer to expose the upper surfaces of the independent heating electrode pins and the common heating electrode pins.

Specifically, as shown in fig. 3, by combining positive photoresist lithography with RIE and ICP etching processes, insulating layer materials above the heating electrode pin pad1 and the heating electrode pin pad2 are etched and penetrated, so that the upper parts of the heating electrode pin pad1 and the heating electrode pin pad2 are exposed, and subsequent bonding is facilitated.

S6, forming corrosion windows around the gas-sensitive detection area, wherein the corrosion windows penetrate through the insulating layer and the cantilever supporting layer.

Specifically, through the combination of positive photoresist photoetching, RIE and ICP etching processes, the insulating layer, the supporting layer silicon oxide and the silicon nitride material in the corrosion area are etched and removed, the upper part of the silicon of the wafer substrate is exposed, the whole wafer is placed into the corrosion liquid, and the silicon of the wafer substrate is etched in a directional manner, so that a corrosion cavity is formed, and a cantilever and a gas detection area with a three-dimensional suspended structure are formed above the corrosion cavity.

S7, forming a gas-sensitive material film on each gas-sensitive detection area through deposition and sputtering; the gas-sensitive material film is laid on the two test electrodes in a flat way.

The metal oxide semiconductor gas-sensitive film is formed on the gas-sensitive detection area by means of deposition, sputtering and the like. Specifically, the deposition of the gas-sensitive film is carried out by means of magnetron sputtering, ALD and the like, and the deposition material can be IGO, cuO, tiO ₂ And the thickness is about 500nm, and the gas-sensitive films are deposited on different gas detection areas on the same sensor array by using a hard mask, so that the sensing function is realized, and the film formation of the gas-sensitive films can be realized by using the hard mask.

And S8, carrying out a dicing process on the silicon-based MEMS gas sensor array prepared at the wafer level to obtain a single silicon-based MEMS gas sensor.

Specifically, after the wafer-level preparation of the MEMS sensor array chips is completed, the MEMS sensor array chips are independently cut into single chips from the wafer by a dicing cutter, and the complete wafer-level process can ensure the process consistency among different sensor array chips and provide a guarantee for the reusability of an algorithm.

Example 3

A silicon-based MEMS gas sensor array chip adopts the silicon-based MEMS gas sensor array chip structure described in the embodiment 1, and the preparation method adopts the preparation method of the silicon-based MEMS gas sensor array chip structure described in the embodiment 2.

The method comprises the steps of preparing different gas-sensitive material films in 4 gas detection areas, wherein the detection capability of a metal oxide semiconductor on gas is directly related to the working temperature, different response trends can be shown when the same metal oxide semiconductor is detected at different working temperatures, and response waveforms can be obviously different. Illustratively, snO2 and catalyst Pd are prepared in the gas detection zone 1 for realizing high-sensitivity hydrogen detection; preparing WO3 in a gas detection zone 2 for high-sensitivity detection of ethanol; preparing an IGO material in a gas detection zone 3 for high-sensitivity detection of formaldehyde; ce-doped NiO was prepared in the gas detection zone 4 for highly sensitive detection of NO 2.

The silicon-based MEMS gas sensor array chip prepared in the embodiment is used for carrying out multi-group experimental detection on the four target gases with different concentrations, and four voltages of V1, V2, V3 and V4 (which can provide the optimal working temperature for a metal oxide semiconductor on the gas detection area or provide other working temperatures which can present special gas-sensitive response trends) are applied to 4 gas detection areas, so that the detection data can be identified and classified by using a pattern recognition algorithm, such as PCA, LDA and other algorithms, and the intelligent detection of the MEMS gas sensor array chip can be realized.

Furthermore, when detecting one gas, different voltages can be applied to different gas-sensitive detection areas, so that different working temperatures are provided, and the target gas is subjected to gas-sensitive detection, so that the rapid screening of the optimal working temperature of the gas-sensitive material can be realized.

In another embodiment, different voltages are applied to different gas sensitive detection areas so as to provide different working temperatures, and different response trends of the same metal oxide semiconductor at different working temperatures can be utilized to realize the distinction of multiple target gases.

Based on the above embodiments, the gas-sensitive detection is performed on 4 gas-sensitive detection areas by using any gas-sensitive detection material and providing any working temperature, wherein the gas-sensitive materials on different gas-sensitive detection areas can be the same or different, and the working temperatures provided by different gas-sensitive detection areas can be the same or different.

When the silicon-based MEMS gas sensor provided by the embodiment of the application is used for gas detection, the serpentine heating electrode in the gas-sensitive detection area is connected with the heating electrode pin pad to form an independent loop, so that independent voltage input control can be realized, different working temperatures can be provided for the metal oxide semiconductor gas-sensitive materials on each gas detection film area, gas-sensitive detection data of the same gas-sensitive material at different temperatures can be obtained, the gas-sensitive detection data of a plurality of gas-sensitive materials at the same time and at the optimal working temperature can be ensured, the data quantity is enriched, and a diversified solution is provided for intelligent gas identification.

It should be noted that the connection manner of the electrode and the pad provided in this embodiment is only a typical representation, and is not limited to the present application, and other connection manners with the same concept can be explained by the present application.

It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the application and is not intended to limit the application, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the application are intended to be included within the scope of the application.

Claims (7)

1. A silicon-based MEMS gas sensor, comprising: a silicon wafer substrate, a detection area arranged above the corrosion cavity of the silicon wafer substrate, and a control electrode area arranged around the corrosion cavity;

the detection areas comprise 4 gas-sensitive detection areas which are arranged in a shape of Chinese character 'tian'; the control electrode area comprises 4 independent heating electrode pins, 4 independent test electrode pins, 2 common heating electrode pins and 2 common test electrode pins;

the heating electrode layer of the gas-sensitive detection area comprises a heating electrode, and the testing electrode layer comprises two testing electrodes; one end of the heating electrode is connected with the independent heating electrode pin, and the other end of the heating electrode is connected with the heating electrode of the gas-sensitive detection area adjacent to the vertical direction and is commonly connected with a common heating electrode pin;

the gas sensitive material film of the gas sensitive detection area is laid on the two test electrodes in a flat way; the test electrode comprises an independent test electrode and a common test sub-electrode, and forms an interdigital electrode; the four common test sub-electrodes form a complete common test electrode; the independent test electrode is connected with the independent test electrode pin, and two ends of the common test electrode are connected with the common test electrode pin;

and independently controlling the temperature of each gas-sensitive detection area through an independent heating electrode pin, and independently detecting the gas-sensitive detection areas through independent testing electrode pins.

2. The silicon-based MEMS gas sensor of claim 1, wherein the heater electrode is strip-shaped and uniformly meanders in the heater electrode layer of the gas sensitive detection zone.

3. The silicon-based MEMS gas sensor of claim 1, wherein the etched cavity is located at the center of the silicon wafer substrate, the cantilever support layer of the gas-sensitive detection zone comprises cantilever beams, cantilever beams are respectively arranged at symmetry axes of the gas-sensitive detection zone in a horizontal direction and a vertical direction, and the 4 cantilever beams of the detection zone are jointly supported above the cavity of the silicon wafer substrate to form a suspended structure.

4. A silicon-based MEMS gas sensor array comprising a plurality of silicon-based MEMS gas sensors as claimed in any one of claims 1-4.

5. A method for manufacturing a silicon-based MEMS gas sensor according to any of claims 1-4, comprising the steps of:

s1, depositing an insulating material on the surface of a silicon wafer substrate at a wafer level to form a cantilever supporting layer covered on the silicon wafer substrate;

s2, depositing metal on the cantilever support layer at the wafer level, forming a heating electrode in the detection area, and forming a heating electrode pin in the control electrode area; the detection areas comprise 4 gas-sensitive detection areas which are arranged in a shape of Chinese character 'tian'; the control electrode zone comprises 4 independent heating electrode pins and 2 common heating electrode pins; one end of the heating electrode of the gas-sensitive detection area is connected with an independent heating electrode pin, and the other end of the heating electrode of the gas-sensitive detection area adjacent to the heating electrode in the vertical direction is connected with the heating electrode pin and is commonly connected with a common heating electrode pin;

s3, depositing an insulating material on the surface of the heating electrode at a wafer level to form an insulating layer covering the cantilever supporting layer and the heating electrode;

s4, depositing metal on the insulating layer at the wafer level, forming a test electrode in the detection area, and forming a test electrode in the control electrode area; the control electrode region comprises 4 independent test electrode pins and 2 common test electrode pins; the test electrode comprises an independent test electrode and a common test sub-electrode, and forms an interdigital electrode; the four common test sub-electrodes form a complete common test electrode; the independent test electrode is connected with the independent test electrode pin, and two ends of the common test electrode are connected with the common test electrode pin;

s5, forming etching windows above each independent heating electrode pin and each common heating electrode pin, wherein the etching windows penetrate through the insulating layer to expose the upper surfaces of the independent heating electrode pins and the common heating electrode pins;

s6, forming corrosion windows around the gas-sensitive detection area, wherein the corrosion windows penetrate through the insulating layer and the cantilever support layer;

s7, forming a gas-sensitive material film on each gas-sensitive detection area through deposition and sputtering; the gas-sensitive material film is laid on the two test electrodes in a flat way;

and S8, carrying out a dicing process on the silicon-based MEMS gas sensor array prepared at the wafer level to obtain a single silicon-based MEMS gas sensor.

6. The method of fabricating a silicon-based MEMS gas sensor as defined in claim 5, wherein the cantilever support layer material is an ONO composite material; wherein the thickness of the first layer of silicon oxide ranges from 100nm to 200nm, the thickness of the second layer of silicon nitride ranges from 300nm to 700nm, and the thickness of the third layer of silicon oxide ranges from 500nm to 1100nm.

7. The method of fabricating a silicon-based MEMS gas sensor as defined in claim 5 wherein the heater electrode is a uniformly serpentine metal electrode;

the insulating layer material is silicon oxide or silicon nitride or a mixed material of the silicon oxide and the silicon nitride;

the test electrode comprises an independent test electrode and a common test sub-electrode to form an interdigital electrode; the four common test sub-electrodes form a complete common test electrode;

the etching solution adopted by the etching window is tetramethyl ammonium hydroxide, so that an etching cavity is formed below the gas-sensitive material film, and only the gas-sensitive detection area and the cantilever beam carrying the electrode are reserved;

the gas-sensitive material film is made of metal oxide semiconductor material, and the thickness range is 100nm-800nm.