A novel MEMS multi-dimensional gas sensor chip and a preparation process thereof

Abstract

The application relates to the technical field of sensing circuit, in particular to a novel MEMS multi-dimensional gas sensor chip and a preparation process thereof, which comprises a heating unit, a light excitation unit and a gas sensitive unit; the heating unit comprises a substrate layer, a passivation dielectric layer one, a polycrystalline silicon deposition layer, a heating resistor, an isolation channel and a passivation dielectric layer two; the top of the substrate layer is sequentially paved with the passivation dielectric layer one and the polycrystalline silicon deposition layer from bottom to top, the heating resistor is ion implanted on the polycrystalline silicon deposition layer, the isolation channel is etched on the polycrystalline silicon deposition layer, the top of the polycrystalline silicon deposition layer is paved with the passivation dielectric layer two, and the isolation channel is filled and the heating resistor is covered. Based on the principle that different concentrations and different components of gas produce different sensing electric signals under different temperature and light condition combinations, the multi-dimensional gas sensing data of a complex gas environment can be collected.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensing circuit, in particular to a novel MEMS multi-dimensional gas sensor chip and a preparation process thereof. BACKGROUND

[0002] Compared with traditional electrochemical sensors, MEMS gas sensor chips taking gas-sensitive resistance materials as the core have been widely applied in environmental safety, mine drilling, border defense, public health, food safety, explosion prevention and other industry fields. The detected gas objects are also various due to different application industries and scenes. The basic principle of the sensor chip taking gas-sensitive resistance materials as the core is relatively direct, that is, electric adsorption and electron exchange occur between the surface of the gas-sensitive material and the gas molecule group, thereby changing the overall conductivity of the gas-sensitive material film. Therefore, the chemical properties of the surface of the gas-sensitive film, the film surface ratio, the film thickness and other parameters directly affect the detection sensitivity of the gas sensor chip.

[0003] At present, the gas sensor chips taking gas-sensitive resistance materials as the sensing core mainly have two categories in terms of working form: thermal excitation and light excitation. Among them, the thermal excitation gas sensor has a long history, which is heated to a high temperature state (above 200℃) so that the surface of the gas-sensitive film material presents chemical sensitivity to specific gas components. For a long time, although the thermal excitation principle has been widely applied to MEMS gas sensors, due to its high-temperature working state exceeding the ignition point of many gases, its application scene is strictly controlled, especially in the fields of flammable and explosive gas detection such as mine, drilling, security and the like. Correspondingly, the working principle of the light excitation gas sensor is to use ultraviolet or visible light irradiation to make the electrons on the surface of the irradiated material in an excited state, thereby producing an oxidation-reduction reaction with the contact gas at room temperature. Therefore, the light excitation gas sensor can significantly reduce the possibility of explosion during the detection of flammable and explosive gases. However, the light excitation gas sensor mechanism has a higher requirement for the photoelectric response capability of the gas-sensitive material, which increases the difficulty of sensor processing. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application discloses a novel MEMS multi-dimensional gas sensor chip and device. The novel MEMS multi-dimensional gas sensor chip integrates a heating unit, a gas-sensitive unit and a light excitation unit on a single silicon substrate; the gas-sensitive unit prepared from a gas-sensitive material performs an oxidation-reduction reaction in an environmental gas; based on the principle that the gas-sensitive material produces different sensing electric signals under different combinations of temperature and light conditions for different concentrations and different components of the gas, the multi-dimensional gas sensing data of a complex gas environment is collected.

[0005] The present application is implemented by the following technical solutions:

[0006] A novel MEMS multi-dimensional gas sensor chip, comprising a heating unit, a light excitation unit and a gas sensitive unit; the heating unit comprises a substrate layer, a passivation medium layer one, a polysilicon deposition layer, a heating resistor, an isolation channel and a passivation medium layer two; the top of the substrate layer is sequentially laid with the passivation medium layer one and the polysilicon deposition layer from bottom to top, the heating resistor is ion implanted on the polysilicon deposition layer, at the same time, the isolation channel is etched on the polysilicon deposition layer, the top of the polysilicon deposition layer is laid with the passivation medium layer two, and the isolation channel is filled and the heating resistor is covered, the middle of the top of the passivation medium layer two is laid with the gas sensitive unit, and the light excitation unit is laid on both sides of the gas sensitive unit.

[0007] Preferably, the substrate layer adopts a thin film structure material with a bottom photoetching overhang, and the thin film structure material adopts silicon, silicon nitride or silicon carbide.

[0008] Preferably, the passivation medium layer one adopts a silicon nitride or silicon carbide thin film material.

[0009] Preferably, the polysilicon deposition layer comprises a seed layer PolySi and an epitaxial layer Epi-PolySi; the epitaxial layer Epi-PolySi is grown on the seed layer PolySi by epitaxy.

[0010] Preferably, the passivation medium layer two adopts an oxidation layer material.

[0011] Preferably, the gas sensitive unit comprises a metal electrode one and a gas sensitive resistor layer; two metal electrode ones are symmetrically arranged on both sides of the middle of the top of the passivation medium layer two, and the gas sensitive resistor layer is covered and laid on the two metal electrode ones.

[0012] Preferably, the metal electrode one adopts a gold, platinum gold or titanium material; and the gas sensitive resistor layer adopts a copper oxide, zinc oxide or tin oxide metal oxide material.

[0013] Preferably, the light excitation unit comprises a laser emission diode, a light waveguide and a light reflection layer; the laser emission diode comprises an n-type GaN layer, an InGaN / GaN quantum well layer, a p-type GaN layer, an ITO layer and a metal electrode two; the top of the n-type GaN layer close to one side of the gas sensitive unit is sequentially laid with the InGaN / GaN quantum well layer, the p-type GaN layer and the ITO layer from bottom to top, the top of the n-type GaN layer away from the gas sensitive unit side and the top of the ITO layer are sequentially laid with the light waveguide and the light reflection layer from bottom to top, and two metal electrode twos are arranged in each light waveguide, one of which is located on the top of the n-type GaN layer, and the other is located on the top of the ITO layer.

[0014] Preferably, the optical waveguide adopts a silicon dioxide medium layer material, and the light reflection layer adopts a metal aluminum material.

[0015] The application further provides a preparation process of the novel MEMS multi-dimensional gas sensor chip.

[0016] S1: first, backside first photoetching is performed on a wafer, a suspended silicon membrane is made through a TMAH or KOH deep silicon etching method, then a passivation medium layer one is deposited on the front side of the suspended silicon membrane;

[0017] S2: a seed layer PolySi of polysilicon is deposited on the passivation medium layer one through LPCVD, and an epitaxial layer Epi-PolySi of polysilicon is grown on the seed layer PolySi through epitaxial growth;

[0018] S3: second photoetching is performed, then a heating resistance wire and an interconnection circuit are made on the epitaxial layer Epi-PolySi material layer through ion implantation, a current path is defined on the surface of the polysilicon through the implantation process and a heating resistance is formed by adjusting the resistance value;

[0019] S4: third photoetching is performed, an isolation channel is made through DeepRIE dry etching technology, an oxide layer is grown as a passivation medium layer two, and the isolation channel is filled in the deposition process;

[0020] S5: a light excitation material layer is stacked on the passivation medium layer two, an n-type GaN layer is stacked through MOCVD technology (Metal Organic Chemical Vapor Desposition), fourth photoetching is performed, RIE etching is completed, metal evaporation is performed, fifth photoetching is performed, and the manufacturing of a metal electrode one on the passivation medium layer two is completed;

[0021] S6: a gas-sensitive resistance layer material is deposited, sixth photoetching is performed, and the manufacturing of a gas-sensitive unit is completed;

[0022] S7: InGaN / GaN quantum well layers and p-type GaN layers are deposited through MOCVD technology, seventh photoetching is performed, RIE etching is performed, eighth and ninth photoetching are performed, respectively, and the manufacturing of an ITO layer and circuit leads is completed through liftoff technology, respectively;

[0023] S8: a silicon dioxide medium layer is deposited through PECVD technology, an aluminum metal layer is deposited, and tenth photoetching is performed to complete the manufacturing of a key step.

[0024] The application has the following beneficial effects:

[0025] 1. Unlike the current way of forming multiple styles of arrays by arranging and combining multiple single-function gas sensors to output multi-dimensional gas sensing data in a whole way, the sensor chip of the present application allows multi-dimensional data collection of target gas on a single chip in design. The multi-dimensional data refers to the measurement data matrix of the gas sensitive material resistance generated by the complex environmental gas under the temperature dimension and the light excitation condition dimension. The chip of the present application has the advantages that the micro-nano heating unit is integrated directly below the light-sensitive sensing unit in the chip design, greatly shortening the heat conduction distance and improving the heating efficiency; at the same time, the micro-nano heating unit is designed on the suspended silicon nitride diaphragm to effectively prevent the rapid loss of heat from the light-sensitive unit in the opposite direction along the substrate, so that the micro-nano heating unit can maintain a relatively high local temperature while greatly saving energy consumption.

[0026] 2. The technical advantage of the present application also lies in that the excitation light source is integrated on the side of the gas sensitive unit to irradiate the surface of the gas sensitive material at a short distance. The traditional excitation light source irradiation scheme takes into account the flow of gas on the surface of the sensing chip, and generally uses a single light source to irradiate the sensor chip at a certain distance. The inverse relationship between the irradiation distance and the irradiation angle makes it necessary to use a larger light source area and energy consumption to ensure that the chips in the entire array can obtain relatively consistent excitation incident energy. The present application uses the standard process of integrated circuit to integrate the gas sensitive unit and the excitation light source at the chip level under the premise of controllable light source parameter error, greatly reducing the irradiation distance and significantly reducing the energy consumption requirement of the light source.

[0027] 3. In the preparation process, the standard process module of the modern integrated circuit production platform is fully utilized in combination with part of the special process, and the process flow is compatible with the current mainstream process platform through innovative design, so that mass production is realized to reduce the cost of a single chip. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0029] Figure 1 It is the overall structure section view of the present application.

[0030] Figure 2 It is the processing and manufacturing diagram of the substrate layer of the present application.

[0031] Figure 3 It is the manufacturing diagram of completing two layers of passivation medium layer of the present application.

[0032] Figure 4 This diagram illustrates the deposition of the gas-sensitive resistor material and the fabrication of the p-type GaN layer for this invention.

[0033] Figure 5 This is a diagram illustrating the fabrication of the second metal electrode according to the present invention.

[0034] Figure 6 This diagram illustrates the fabrication process of depositing silicon dioxide, evaporating aluminum, and performing photolithography on the RIE (Reinforced Interchange Electrode).

[0035] In the figure: 1-substrate layer, 2-passivation dielectric layer one, 3-polysilicon deposition layer, 4-passivation dielectric layer two, 5-thermal resistor, 6-n-type GaN layer, 7-InGaN / GaN quantum well layer, 8-p-type GaN layer, 9-ITO layer, 10-optical waveguide, 11-optical reflective layer, 12-metal electrode one, 13-gas-sensitive resistor layer, 14-metal electrode two;

[0036] 1-1: Wafer; 1-2: Photoresist; 1-3 Wet etching cross-section of silicon; 2-1: Silicon wafer; 2-2 Dielectric layer one; 2-3: Polysilicon (PolySi); 2-4: Ion implantation; 2-5: Isolation channel; 2-6: Dielectric layer two; 3-1: MOCVD deposition of n-type GaN; 3-2: Photolithography and RIE etching; 3-3: Metal evaporation, etching, and fabrication of bottom electrode; 3-4: Gas-sensitive resistor material deposition; 3-5: MOCVD deposition of InGaN / GaN quantum well layer; 3-6: MOCVD deposition of p-type GaN layer; 4-1: Photolithography and RIE etching; 4-2: Liftoff fabrication of ITO layer; 4-3: Liftoff fabrication of metal electrode; 5-1: PECVD deposition of SiO2; 5-2: Aluminum evaporation; 5-3: Photolithography and RIE. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1:

[0039] like Figures 1-6As shown, a novel MEMS multi-dimensional gas sensor chip includes a heating unit, a light excitation unit and a gas sensitive unit; the heating unit includes a substrate layer 1, a passivation dielectric layer one 2, a polycrystalline silicon deposition layer 3, a heating resistor 5, an isolation channel and a passivation dielectric layer two 4; the top of the substrate layer 1 is sequentially laid with the passivation dielectric layer one 2 and the polycrystalline silicon deposition layer 3 from bottom to top, the polycrystalline silicon deposition layer 3 is ion implanted with the heating resistor 5, and the polycrystalline silicon deposition layer 3 is etched with the isolation channel, the top of the polycrystalline silicon deposition layer 3 is laid with the passivation dielectric layer two 4, and the isolation channel is filled and the heating resistor 5 is covered, the middle of the top of the passivation dielectric layer two 4 is laid with the gas sensitive unit, and the light excitation unit is laid on both sides of the gas sensitive unit.

[0040] The substrate layer 1 adopts a thin film structure material suspended by bottom photolithography, and the thin film structure material adopts silicon, silicon nitride or silicon carbide.

[0041] The passivation dielectric layer one 2 adopts a silicon nitride or silicon carbide thin film material.

[0042] The polycrystalline silicon deposition layer 3 includes a seed layer PolySi and an epitaxial layer Epi-PolySi; the epitaxial layer Epi-PolySi is grown on the seed layer PolySi by epitaxy.

[0043] The passivation dielectric layer two 4 adopts an oxidation layer material.

[0044] The gas sensitive unit includes a metal electrode one 12 and a gas sensitive resistor layer 13; two metal electrode ones 12 are symmetrically arranged on the middle of the top of the passivation dielectric layer two 4, and the gas sensitive resistor layer 13 is laid on the two metal electrode ones 12.

[0045] The metal electrode one 12 adopts gold, platinum gold or titanium material; the gas sensitive resistor layer 13 adopts copper oxide, zinc oxide or tin oxide metal oxide material.

[0046] The light excitation unit includes a laser emission diode, a light waveguide 10 and a light reflection layer 11; the laser emission diode includes an n-type GaN layer 6, an InGaN / GaN quantum well layer 7, a p-type GaN layer 8, an ITO layer 9 and a metal electrode two 14; the top of the n-type GaN layer 6 close to one side of the gas sensitive unit is sequentially laid with the InGaN / GaN quantum well layer 7, the p-type GaN layer 8 and the ITO layer 9 from bottom to top, the top of the n-type GaN layer 6 far from one side of the gas sensitive unit and the top of the ITO layer 9 are sequentially laid with the light waveguide 10 and the light reflection layer 11 from bottom to top, and two metal electrode twos 14 are arranged in each light waveguide 10, one of which is located on the top of the n-type GaN layer 6, and the other is located on the top of the ITO layer 9.

[0047] The light waveguide 10 adopts a silicon dioxide dielectric layer material, and the light reflection layer 11 adopts a metal aluminum material.

[0048] The design principle of the present application is as follows: the heating unit adopts the mature resistance heating principle, and heats the whole chip device within a control range by consuming electric energy. The suspended thin film structure laid under the heating unit reduces the heat conduction cross section between the heating unit and the substrate material. The suspended thin film can be a single silicon material, or a composite material such as silicon nitride and silicon carbide which can significantly reduce the heat conduction coefficient of the bottom of the heating unit and the overall thermal expansion coefficient of the thin film, to ensure lower energy consumption and smaller thermal stress. The medium layer laid on the heating unit is used to physically isolate the electrical connection between the heating unit and the gas sensitive unit. The gas sensitive unit is composed of a metal electrode at the bottom and a gas sensitive resistance material attached thereto. The metal electrode can be gold, platinum gold, titanium, etc. in material. The gas sensitive resistance material can be metal oxide such as copper oxide, zinc oxide and tin oxide. The working principle of the gas sensitive unit is that when the target gas molecules adhere to the surface of the gas sensitive resistance material, the electron exchange process generated in the chemical process affects the conductivity of the material within a certain depth range. Therefore, the thickness of the gas sensitive unit will significantly affect the overall working efficiency of the gas sensor chip in the present application. On both sides of the gas sensitive unit are the light excitation units, which are composed of a laser emitting diode and a light guide 10. The function of the light excitation unit is to irradiate the gas sensitive resistance material according to the control, and adjust the chemical activity of the gas sensitive resistance material through light excitation. The light guide 10 is composed of silicon dioxide and a metal layer attached thereto, and finally guides and irradiates light to the surface of the gas sensitive resistance material by changing the light transmission path.

[0049] Embodiment 2:

[0050] The present application also provides a preparation process of a new type of MEMS multi-dimensional gas sensor chip as in Embodiment 1 above, comprising the following steps:

[0051] S1: First, backside first photoetching is performed on the wafer, and the suspended silicon film is made by TMAH or KOH deep silicon etching method, and then a passivation medium layer 2 is deposited on the front side of the suspended silicon film;

[0052] S2: A seed layer PolySi of polysilicon is deposited on the passivation medium layer 2 by LPCVD, and an epitaxial layer Epi-PolySi of polysilicon is grown on the seed layer PolySi by epitaxial growth;

[0053] S3: The second step of photoetching is performed, and then the heating resistor 5 and the interconnection circuit are made in the epitaxial layer Epi-PolySi material layer by ion implantation, and the current path is defined and the resistance value is adjusted on the surface of the polysilicon to form the heating resistor 5;

[0054] S4: Implementing the third step of photoetching, using DeepRIE dry etching technology to make the isolation channel, growing the oxide layer as the second passivation medium layer 4, and filling the isolation channel in the process of deposition;

[0055] S5: Starting to stack the photoexcitation material layer on the second passivation medium layer 4, using MOCVD technology (Metal Organic Chemical Vapor Desposition) to stack the n-type GaN layer 6 first, implementing the fourth step of photoetching, completing RIE etching, performing metal evaporation, and then implementing the fifth step of photoetching to complete the fabrication of the metal electrode 12 on the second passivation medium layer 4;

[0056] S6: Depositing the gas-sensitive resistance layer 13 material, implementing the sixth step of photoetching to complete the fabrication of the gas-sensitive unit;

[0057] S7: Continuing to deposit the InGaN / GaN quantum well layer 7 and the p-type GaN layer 8 using MOCVD technology, implementing the seventh step of photoetching using RIE technology for etching, respectively implementing the eighth and ninth steps of photoetching, and respectively completing the fabrication of the ITO layer 9 and the circuit lead through the liftoff technology;

[0058] S8: Depositing the silicon dioxide medium layer through PECVD technology, then depositing the aluminum metal layer, and implementing the tenth step of photoetching to complete the fabrication of the key step.

[0059] Example 3:

[0060] The working process of the present application is described as follows: As a multi-dimensional MEMS gas sensor chip, the working mode of the device disclosed in the present application provides the following description:

[0061] The chip realizes the following four working modes under room temperature conditions:

[0062] Working mode 1: The heating unit and the photoexcitation unit are turned off, and the impedance of the gas-sensitive unit electrode is measured.

[0063] Working mode 2: The chip is powered on with the heating unit turned on and the photoexcitation unit turned off. After the chip is in the self-heating process and self-heated to the target temperature and keeps the temperature stable, the impedance of the gas-sensitive unit electrode at different time points is detected.

[0064] Working mode 3: The chip heating unit is turned off, and the photoexcitation unit is powered on. During the irradiation of the surface of the gas-sensitive unit, the impedance of the gas-sensitive unit at different time points is detected.

[0065] Working mode 4: The chip heating unit is powered on, and the photoexcitation unit is powered on. The impedance of the gas-sensitive unit at different time points is detected.

[0066] In the above four working modes, the chip working mode switching sequence is not limited to the above described sequence. Meanwhile, the interval time during the mode switching of the chip does not limit the rights claimed in the patent. For example, in the implementation process of switching from working mode 2 to working mode 1 of the chip, insufficient switching interval time will cause the chip to start the detection of working mode 1 without returning to room temperature. Similarly, in the process of switching from working mode 2 to working mode 3, insufficient switching interval time will cause the starting detection temperature of mode 3 detection to not be strictly room temperature. Adjusting the working mode switching time interval can make the detection data have valuable information, thereby leading to new use methods of the sensor of the present application beyond the implementation cases.

[0067] In addition to the switching time interval, the synchronization or asynchronization of the opening and closing of the sub-units in the above four working modes is also the rights claimed in the present application. For example, after the working mode 4 is opened, the opening timing of the sub-units can be synchronous or asynchronous, and during the process of keeping one sub-unit open, another sub-unit can be continuously opened or intermittently opened and closed, and the intermittent time is not limited. In the same working mode, by adjusting the combination of the opening and closing states of the sub-units and the combination of the switching frequencies, valuable information can be obtained from the detection data, thereby leading to new use methods of the sensor of the present application beyond the implementation cases.

[0068] In the working state of fixed working mode and fixed sub-unit switching state, the multi-dimensional data collection function can still be realized by quantitatively adjusting the working parameters of the sub-units. For example, when the chip is in the state of working mode 2, the heating unit is opened, and the corresponding data output change on the time axis can be realized by linearly or nonlinearly adjusting the working temperature change of the heating unit. Similarly, when the chip is in the state of working mode 3, the light excitation unit is opened, and the corresponding data output on the time axis can be realized by linearly or nonlinearly adjusting the output light intensity of the light excitation unit. This detection method can also output valuable gas sensing information, thereby leading to new use methods of the sensor of the present application beyond the implementation cases.

[0069] The above examples are only used to illustrate the technical solutions of the present application, but not limit the same; during the manufacturing process of the heating unit, the adjustment and change of ion implantation concentration do not affect the claimed invention of the present patent. The change range, frequency and change rule of temperature of the heating unit during the working process do not constitute substantial difference from the present application. The gas sensitive material used during the manufacturing process of the gas sensitive unit does not hinder the change in the working mode required by the present application. The selection of the gas sensitive material and the correlation of the deposition process involved during the manufacturing process, i.e. different gas sensitive materials may require different deposition processes, do not constitute substantial difference from the description of the "gas sensitive resistance material" and "deposition" of the present application, and all are to manufacture the gas sensitive unit on the heating unit through the deposition process. The deposition process of the gas sensitive material can include evaporation, sputtering, wet oxidation, spin coating and other processing technologies. The light reflecting layer of the light excitation unit is made of aluminum in the examples, but the use of other metals does not constitute substantial difference from the description of the metal reflecting layer involved in the present application. During the processing flow, the angle of the deposition and etching part is shown as a right angle in the drawing, however, in the actual production and manufacturing process, due to the differences in equipment, materials and processing technology, the right angle part cannot be realized. Any attempt to describe the flow process claimed in the present application in the form of obtuse angle, chamfer, arc and the like during the flow drawing process does not constitute substantial difference from the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A novel MEMS multi-dimensional gas sensor chip, characterized by, The application relates to a gas sensor, which comprises a heating unit, a light excitation unit and a gas sensitive unit; the heating unit comprises a substrate layer, a passivation medium layer one, a polycrystalline silicon deposition layer, a heating resistor, an isolation channel and a passivation medium layer two; the top of the substrate layer is sequentially provided with the passivation medium layer one and the polycrystalline silicon deposition layer from bottom to top, the heating resistor is ion implanted on the polycrystalline silicon deposition layer, meanwhile, the isolation channel is etched on the polycrystalline silicon deposition layer, the top of the polycrystalline silicon deposition layer is provided with the passivation medium layer two, the isolation channel is filled and the heating resistor is covered, the middle of the top of the passivation medium layer two is provided with the gas sensitive unit, and the light excitation unit is provided on the two sides of the gas sensitive unit; The light excitation unit comprises a laser emission diode, an optical waveguide and an optical reflection layer; the laser emission diode comprises an n-type GaN layer, an InGaN / GaN quantum well layer, a p-type GaN layer, an ITO layer and a metal electrode two; the top of the n-type GaN layer close to one side of the gas sensitive unit is sequentially provided with the InGaN / GaN quantum well layer, the p-type GaN layer and the ITO layer from bottom to top, the top of the n-type GaN layer far away from one side of the gas sensitive unit and the top of the ITO layer are sequentially provided with the optical waveguide and the optical reflection layer from bottom to top, and two metal electrode twos are arranged in each optical waveguide, one of the metal electrode twos is located on the top of the n-type GaN layer, and the other metal electrode two is located on the top of the ITO layer; The optical waveguide adopts a silicon dioxide medium layer material, and the optical reflection layer adopts a metal aluminum material.

2. A novel MEMS multi-dimensional gas sensor chip as claimed in claim 1, wherein, The substrate layer adopts a bottom photoetching suspended thin film structure material, and the thin film structure material adopts silicon, silicon nitride or silicon carbide.

3. A novel MEMS multi-dimensional gas sensor chip as claimed in claim 1, wherein, The passivation medium layer one adopts a silicon nitride or silicon carbide thin film material.

4. A novel MEMS multi-dimensional gas sensor chip as claimed in claim 1, wherein, The polycrystalline silicon deposition layer comprises a seed layer PolySi and an epitaxial layer Epi-PolySi; the epitaxial layer Epi-PolySi is grown on the seed layer PolySi through epitaxy.

5. A novel MEMS multi-dimensional gas sensor chip as claimed in claim 1, wherein, The passivation medium layer two adopts an oxidation layer material.

6. A novel MEMS multi-dimensional gas sensor chip as claimed in claim 1, wherein, The gas sensitive unit comprises a metal electrode one and a gas sensitive resistor layer; two metal electrode ones are symmetrically arranged on the middle of the top of the passivation medium layer two, and the gas sensitive resistor layer is covered and arranged on the two metal electrode ones.

7. A novel MEMS multi-dimensional gas sensor chip as claimed in claim 6, wherein, The metal electrode one adopts a gold, platinum gold or titanium material; and the gas sensitive resistor layer adopts a copper oxide, zinc oxide or tin oxide metal oxide material.

8. A process for the preparation of a novel MEMS multi-dimensional gas sensor chip as claimed in any one of claims 1 to 7, wherein, The application further discloses a gas sensor manufacturing method, which comprises the following steps: S1: first, back surface first step photoetching is conducted on a wafer, a suspended silicon film is prepared through a TMAH or KOH deep silicon etching method, and then a passivation medium layer one is deposited on the front surface of the suspended silicon film; S2: a seed layer PolySi of polycrystalline silicon is deposited on the passivation medium layer one through LPCVD, and an epitaxial layer Epi-PolySi of polycrystalline silicon is grown on the seed layer PolySi through epitaxy; S3: second step photoetching is conducted, then a heating resistor wire and an interconnection circuit are prepared on the epitaxial layer Epi-PolySi material layer through ion implantation, and the heating resistor is formed; S4: Implement the third step of photoetching, use DeepRIE dry etching technology to make isolation channel, grow oxide layer as passivation medium layer two, and fill the isolation channel in the process of deposition; S5: Start to stack the photoexcitation material layer on the passivation medium layer two, use MOCVD technology to stack n-type GaN layer first, implement the fourth step of photoetching, complete RIE etching, perform metal evaporation, and then implement the fifth step of photoetching to complete the manufacture of the metal electrode one on the passivation medium layer two; S6: Deposit the gas-sensitive resistance layer material, implement the sixth step of photoetching to complete the manufacture of the gas-sensitive unit; S7: Continue to use MOCVD technology to deposit InGaN / GaN quantum well layer and p-type GaN layer, implement the seventh step of photoetching, use RIE technology for etching, respectively implement the eighth and ninth steps of photoetching, and complete the manufacture of ITO layer and circuit lead wire through liftoff technology; S8: Deposit silicon dioxide medium layer through PECVD technology, then deposit aluminum metal layer, and implement the tenth step of photoetching to complete the manufacture of the key step.

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