Miniature integrated infrared gas sensor chip

Abstract

The invention discloses a miniature integrated infrared gas sensor chip, which belongs to the technical field of sensors, and comprises a first wafer and a second wafer, and the first wafer and the second wafer are connected in a combination manner and form an optical gas chamber; a vent hole is formed above the first wafer, and a reflective film layer is plated on the inner wall of the optical gas chamber and is arranged to only allow infrared light emitted by the infrared light source to pass through; a periodic micro-nano structure is arranged in the optical gas chamber; the surface of the second wafer is covered with an insulating film layer, and an infrared light source and an infrared detector are arranged above the insulating film layer. An optical gas chamber is formed through double-wafer bonding, a periodic micro-nano structure is integrated to enhance interaction between infrared light and gas, environmental interference is suppressed in combination with a double-channel differential detector, and meanwhile stability and selectivity are improved through multi-layer structures such as a reflective film layer, a protective film layer and a composite insulating film layer. And finally, a miniaturized and high-sensitivity gas detection function is realized.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology, specifically relating to a miniature integrated infrared gas sensor chip. Background Technology

[0002] Infrared gas sensors detect the concentration of specific gas molecules based on spectral absorption. Infrared light emitted from a light source is reflected multiple times by a gas cell and then passes through a filter to reach the infrared detector. Gas molecules in the gas cell absorb infrared light of specific wavelengths due to molecular vibrations, causing attenuation of the infrared light at that wavelength. The concentration of gas molecules can be obtained by measuring the attenuation of the infrared light intensity before and after the light is emitted.

[0003] Infrared gas sensors have significant advantages such as high accuracy, high stability, good selectivity, non-toxicity, long lifespan, and wide measurement range. They are currently widely used in fields such as medical and health care, smart agriculture, mining, and air pollution control for real-time concentration monitoring of gases such as CO2, CO, and CH4.

[0004] Traditional infrared gas sensors consist of discrete components such as a light source, gas chamber, and detector, resulting in excessively large package sizes (as illustrated in Chinese patent CN104122223B). Miniaturization and integration are difficult to achieve, and costs are high. Silicon-based integration methods based on MEMS can significantly reduce the size of infrared gas sensors. For example, Chinese patent CN 115060682A discloses a chip-level packaged miniature infrared gas sensor where a miniature optics cover, infrared detection chip, and signal processing chip are integrated using MEMS fabrication technology, thereby effectively reducing the size of the infrared gas sensor.

[0005] However, according to the Lambert-Beer law, the intensity of infrared light absorbed by a gas follows this law: (1) in, The intensity of the light received by the detector. The intensity of light emitted by the light source. The absorption coefficient is... The concentration of the gas to be measured. Let be the optical path length. It can be seen that increasing the optical path length improves the sensitivity of the infrared gas sensor, while decreasing the optical path length reduces the sensitivity.

[0006] Because the optical chambers of miniature infrared gas sensors are small, their optical path lengths are often very short, resulting in low sensitivity. To address the difficulty of achieving high sensitivity in miniature sensors, the mainstream solution is to extend the optical path length by modifying the optical cavity structure. Chinese patent CN 103822893 B discloses an infrared gas sensor that extends the optical path length through multiple reflections of light. Compared to traditional linear optical cavities, the cylindrical optical cavity of this invention can improve sensor sensitivity while reducing size and cost. However, to ensure high sensitivity, existing methods for extending the optical path length struggle to achieve a small optical chamber size. Therefore, the sensor remains relatively large, limiting its widespread application in portable consumer electronics, implantable devices, and other fields. Summary of the Invention

[0007] This invention provides a miniature integrated infrared gas sensor chip, which improves the sensitivity of infrared gas sensors with a tiny optical gas cell, thereby solving the technical problems of large size and high cost of existing discrete infrared sensors, and insufficient sensitivity of integrated sensors.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a miniature integrated infrared gas sensor chip, comprising a first wafer and a second wafer, the first wafer and the second wafer being connected by bonding to form an optical gas cell; the surface of the second wafer is covered with an insulating film layer, and an infrared light source and an infrared detector are disposed above the insulating film layer; a vent hole is opened above the first wafer; the inner wall of the optical gas cell is coated with a reflective film layer to reflect the light beam emitted by the infrared light source; The optical chamber is provided with a periodic micro / nano structure; the periodic micro / nano structure includes multiple micro / nano units arranged in an array.

[0009] Furthermore, the micro-nano units are cylinders, cones, prisms, or pyramids, and the arrangement pattern of the periodic micro-nano structures is one or more combinations of rectangles, rhombuses, hexagons, ellipses, circles, and crosses; the upper end of the periodic micro-nano structures is connected to the reflective film layer, and the height of the periodic micro-nano structures is 60%-80% of the height of the optical air cell.

[0010] Furthermore, the infrared detector includes a first infrared detector and a second infrared detector. A first filter film is disposed above the first infrared detector, and a second filter film is disposed above the second infrared detector. The first filter film and the second filter film transmit infrared light with different wavelengths.

[0011] Furthermore, a protective film layer is provided on the infrared light source, and the protective film layer is a SiO2 film layer. Furthermore, the infrared light source is a broadband or narrow-spectrum light source based on a MEMS micro heater, and the micro heater is provided with a radiation layer, which is platinum black, carbon black or polycrystalline silicon.

[0012] Furthermore, the infrared detector can be a MEMS thermopile chip, pyroelectric chip, photodiode, or photoconductive detector.

[0013] Furthermore, the surface of the periodic micro / nano structure is coated with a coating material that is one or a combination of Au, Ag, Cu and Al.

[0014] Furthermore, a TSV via is provided inside the second wafer, through which the infrared light source and infrared detector are electrically connected to the electrodes on the lower surface of the second wafer.

[0015] Furthermore, a metal pad is provided on the insulating film layer. The metal pad is located outside the first wafer and is electrically connected to the infrared light source, the first infrared detector, and the second infrared detector through metal wires on the insulating film layer.

[0016] Furthermore, the insulating film layer is a composite film layer of SiO2-SiNx.

[0017] Compared with the prior art, the present invention has at least the following beneficial technical effects: This invention innovatively proposes an optical cavity with a periodic micro / nano structure. When infrared light is incident on the periodic micro / nano structure, it excites surface plasmon resonance, enhancing the vibrational signal of the target gas molecules and thus significantly strengthening the interaction between infrared light and the target gas, effectively improving the absorption coefficient. Simultaneously, this periodic micro / nano structure can excite photon coupling modes, causing the incident light to be reflected / scattered multiple times near the periodic micro / nano structure-air interface, resulting in a synergistic increase in optical path length. This allows the miniature integrated infrared gas sensor to achieve high-sensitivity gas detection performance even with a small optical cell size. Furthermore, the monolithic integrated infrared light source and infrared detector structure effectively achieves process and material reuse, further reducing the integrated chip size and facilitating miniaturization and cost reduction. This invention fabricates a periodic micro / nano structure within the optical cavity, resulting in a larger aspect ratio, reduced fabrication difficulty, cost savings, and improved yield, demonstrating significant design and manufacturing convenience.

[0018] Furthermore, a protective film and a filter film are respectively covering the infrared light source and the infrared detector, preventing air pollution and mechanical shock from affecting the device performance and enhancing the stability of the sensor during long-term operation. In addition, the filter film effectively improves the sensor's response selectivity to the target gas by selectively transmitting infrared light of specific wavelengths.

[0019] Furthermore, a differential structure consisting of two infrared detectors is set up, which can reduce reading errors caused by changes in air humidity and ambient temperature, and significantly reduce sensor performance drift caused by changes in infrared light source temperature. Attached Figure Description

[0020] Figure 1 This is a top view of the MEMS-based miniature integrated infrared gas sensor chip provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of a stepped cross-section of a MEMS-based miniature integrated infrared gas sensor chip provided in Embodiment 1 of the present invention; the stepped cross-section is located at... Figure 1 As shown in the image; Figure 3 A three-dimensional structural schematic diagram of the MEMS-based miniature integrated infrared gas sensor provided in Embodiment 1 of the present invention;

[0021] Figure 4 This is a first wafer bottom view of the MEMS-based miniature integrated infrared gas sensor provided in one embodiment of the present invention; Figure 5 This is a top view of the second wafer of the MEMS-based miniature integrated infrared gas sensor provided in Embodiment 1 of the present invention, after the protective film and filter film have been removed. Figure 6 This is a schematic diagram of the stepped cross-section of the miniature integrated infrared gas sensor chip provided in Embodiment 2 of the present invention.

[0022] Figure label: 1. Vent hole; 2. First wafer; 3. Reflective film layer; 4. First filter film layer; 5. First infrared detector; 6. TSV via; 7. Electrode; 8. Second wafer; 9. Insulating film layer; 10. Protective film layer; 11. Infrared light source; 12. Periodic micro / nano structure; 13. Optical gas cell; 14. Second infrared detector; 15. Second filter film layer; 16. Metal pad. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0024] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0025] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or may be interposed with another element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or may be interposed with another element. The terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., used herein to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] Example 1 Reference Figures 1 to 4 The present invention provides a miniature integrated infrared gas sensor chip, the sensor comprising: a vent 1, a first wafer 2, a reflective film layer 3, a first filter film layer 4, a first infrared detector 5, a TSV via 6, an electrode 7, a second wafer 8, an insulating film layer 9, a protective film layer 10, an infrared light source 11, a periodic micro / nano structure 12, an optical gas cell 13, a second infrared detector 14, and a second filter film layer 15.

[0028] The first wafer 2 has a groove at its lower part. The first wafer 2 and the second wafer 8 are bonded together to form an optical gas chamber 13. Multiple ventilation holes 1 are formed above the first wafer 2, allowing the gas inside the optical gas chamber 13 to flow with the external gas, ensuring that the gas composition of the optical gas chamber 13 is the same as that of the outside. The inner wall of the optical gas chamber 13 is coated with a reflective film layer 3, which reflects the light beam emitted by the infrared light source 11, allowing it to reach the first infrared detector 5 and the second infrared detector 14. The periodic micro / nano structure 12 is fabricated on the upper part of the optical gas chamber 13, with its upper end connected to the inner surface of the top wall of the optical gas chamber 13. When the infrared light beam passes through, it can enhance the interaction intensity between the infrared light and the gas through resonance. Simultaneously, this periodic micro / nano structure can excite photon coupling modes, causing the incident light to be reflected / scattered multiple times near the periodic micro / nano structure-air interface, thus synergistically increasing the optical path length l.

[0029] An insulating film layer 9 is disposed on the upper surface of the second wafer 8. An infrared light source 11, a first infrared detector 5, and a second infrared detector 14 are disposed above the insulating film layer 9. A protective film layer 10 covers the infrared light source 11, a first filter film layer 4 covers the first infrared detector 5, and a first filter film layer 15 covers the second infrared detector 14. The infrared light source 11 emits infrared light into the optical chamber 13. The light is first reflected by the reflective film layer 3, then passes through the periodic micro / nano structure 12, and is then reflected again by the reflective film layer 3 to the first filter film layer 4 and the second filter film layer 15, finally entering the first infrared detector 5 and the second infrared detector 14. The first infrared detector 5 and the second infrared detector 14 absorb light beams within a specific wavelength range and convert them into electrical signals. The first infrared detector 5 has a first filter film layer 4, and the second infrared detector 14 has a second filter film layer 15. The first filter film layer 4 and the second filter film layer 15 are made of different materials and can selectively transmit infrared light of different wavelengths, allowing two types of filtered infrared light to reach the first infrared detector 5 and the second infrared detector 14. The first infrared detector 5 is used to detect the characteristic infrared absorption of the target gas in the gas mixture being tested, and the second infrared detector 14 is used to detect the characteristic infrared absorption of water contained in the gas mixture being tested. The first infrared detector 5 and the second infrared detector 14 can form a dual-channel differential structure, which can reduce reading errors caused by changes in air humidity and ambient temperature, and suppress sensor performance drift caused by changes in the temperature of the infrared light source.

[0030] In one specific embodiment, the dimensions of the wafer-level infrared gas sensor are: 7-9 mm in length, 6-10 mm in width, and 3-5 mm in height. The dimensions of the first infrared detector 5 and the second infrared detector 14 are 2×2 mm, and the dimensions of the infrared light source 11 are 1×1 mm.

[0031] The periodic micro / nano structure 12 is a metamaterial composed of multiple arrayed micro / nano units. A metamaterial is an artificial material with a designed subwavelength periodic cell structure. The micro / nano units are one or more combinations of cylinders, cones, prisms, and pyramids. The periodic micro / nano structure 12 is a symmetrical pattern, which is one or more combinations of rectangles, rhombuses, hexagons, ellipses, circles, and crosses.

[0032] Reference Figure 4 In one alternative embodiment, the periodic micro / nano structure 12 is composed of multiple cylindrical micro / nano units arranged in a 10×11 array; In one optional embodiment, the periodic micro / nano structure 12 is formed by a plurality of cylindrical, conical, prismatic or pyramidal micro / nano units arranged periodically in a regular hexagonal lattice; in another optional embodiment, the periodic micro / nano structure 12 includes conical micro / nano units and quadrangular pyramidal micro / nano units, which are mixed and arranged alternately to form a rhombic array.

[0033] In one alternative embodiment, the periodic micro / nano structure 12 includes cylindrical micro / nano units and conical micro / nano units, which are mixed and arranged alternately to form a rhomboid or circular array.

[0034] In one alternative embodiment, the periodic micro / nano structure 12 includes cylindrical micro / nano units, conical micro / nano units, and triangular prism micro / nano units, which are mixed and arranged alternately to form a rhomboid or cross-shaped array.

[0035] The periodic micro / nanostructure is formed by etching on a Si substrate. In the near-infrared band, silicon-based metamaterials can achieve polarization-insensitive absorption. The period of the periodic micro / nanostructure refers to the center-to-center distance between two adjacent micro / nano units, and the period is proportional to the characteristic infrared absorption wavelength of the target gas. The height of the periodic micro / nanostructure 12 is set between 60% and 80% of the height of the optical chamber 13. This ensures that as much light beam as possible passes through the periodic micro / nanostructure 12 while preventing it from contacting the second wafer 8, thus avoiding damage to it.

[0036] The surface of the micro / nano unit is coated with a coating that can enhance the surface plasmon resonance effect near the periodic micro / nano structure 12, thereby further enhancing the interaction between infrared light and gas. At the same time, the coating can reflect infrared light, thereby extending the optical path and improving the detection sensitivity.

[0037] Preferably, the coating material is one or a combination of Au, Ag, Cu, and Al.

[0038] Reference Figure 2 and Figure 5 In one optional embodiment, the second wafer 8 has a TSV via 6 inside, which can supply power and transmit signals to the infrared light source 11, the first infrared detector 5, and the second infrared detector 14. A TSV, or through-silicon via, is a vertical interconnect technology that penetrates a silicon wafer; by drilling holes in the silicon wafer and filling them with conductive material, electrical connections between different chip layers are achieved, significantly shortening the signal transmission path and improving integration and performance. The infrared light source 11, the first infrared detector 5, and the second infrared detector 14 are electrically connected to the electrodes 7 on the lower surface of the second wafer 8 through the conductive layer and the TSV via 6.

[0039] In one optional embodiment, the infrared light source 11 is a broadband or narrowband light source based on a MEMS microheater. It includes a MEMS microheater and a radiating layer disposed thereon, the radiating layer being one of platinum black, carbon black, and polycrystalline silicon. The infrared detector is one of a MEMS thermopile chip, pyroelectric chip, photodiode, and photoconductive detector. There are two infrared detectors, forming a differential structure, one serving as a reference channel and the other as a measurement channel.

[0040] In one alternative embodiment, the vent 1 is positioned optimally using fluid dynamics simulation to maximize the air exchange rate between the optical chamber and the outside environment.

[0041] In one optional embodiment, the left, right, front, and rear surfaces of the inner wall of the optical chamber 13 are coated with a reflective film layer 3. The advantage of this design is that the reflective film layer 3 can reflect the light emitted by the infrared light source 11 onto the periodic micro / nano structure 12, and then reflect it again to the first filter film layer 4 and the second filter film layer 15, ultimately reaching the first infrared detector 5 and the second infrared detector 14. The reflective film layer 3 is made of one or a combination of Au, Al, Ag, and Cu. The left and right inner walls of the optical chamber 13 are planar or curved. Preferably, they are parabolic. The two parabolic inner walls of the optical chamber 13 coated with reflective film layers can form a composite parabolic concentrator to focus the diverging light beam and guide it to the first infrared detector 5 and the second infrared detector 14, achieving a high focusing ratio.

[0042] In an optional embodiment, the insulating film layer 9 is SiO2-SiN. x The composite film layer. The advantage of this design is that the film layer has low thermal conductivity, which reduces the impact of heat generated by the microheater on the temperature of the first infrared detector 5 and the second infrared detector 14; furthermore, the SiO2-SiN composite film layer... x The composite film layer can achieve stress compensation, thus ensuring uniform stress distribution on the film layer. The protective film layer 10 is made of SiO2, which can isolate it from contact with the gas inside the optical gas chamber 13, thereby avoiding gas impact and contamination from affecting the long-term stability of the sensor.

[0043] In an optional embodiment, the first filter layer 4 and the second filter layer 15 can be selected from two or more of Ge, Si, SiO, MgF2, ZnS, ZnSe, CaF2, GaAs, and sapphire as high and low refractive index film materials, respectively. The first filter layer 4 and the second filter layer 15 are made of different materials; the first filter layer 4 selectively transmits infrared light of the wavelength corresponding to the absorption wavelength of the target gas, while the second filter layer 15 selectively transmits infrared light of the wavelength corresponding to the absorption wavelength of moisture in the air. Besides extracting the characteristic absorption wavelength of the target gas and filtering other wavelengths of light, the first filter layer 4 and the second filter layer 15 also protect the first infrared detector 5 and the second infrared detector 14.

[0044] In an optional embodiment, the radiating layer of the infrared light source 11 can also be made of metamaterial, and the upper surfaces of the first infrared detector 5 and the second infrared detector 14 can also be made of metamaterial. For the infrared light source 11, the metamaterial can effectively improve the emissivity of infrared light, and at the same time achieve narrowband emission so that the infrared light source 11 only emits infrared light within a specific wavelength range; for the first infrared detector 5 and the second infrared detector 14, the metamaterial can enhance the absorption of infrared light by the detector, and at the same time achieve narrowband absorption so that the first infrared detector 5 and the second infrared detector 14 only absorb infrared light within a specific wavelength range, thus playing the role of replacing the filter film layer.

[0045] Example 2 refer to Figure 6 This embodiment proposes an infrared gas sensor structure with the same working principle as Embodiment 1. The difference between this embodiment and Embodiment 1 lies in the conductivity of the infrared light source 11, the first infrared detector 5, and the second infrared detector 14. In this embodiment, the infrared light source 11, the first infrared detector 5, and the second infrared detector 14 are not connected to the electrode 7 through TSV vias. Instead, they are connected to the external circuit via metal pads 16 and leads. The metal pads 16 are disposed on the insulating film layer 9, located outside the first wafer 2, and electrically connected to the infrared light source 11, the first infrared detector 5, and the second infrared detector 14 through metal wires on the insulating film layer. Compared to Embodiment 1, this embodiment uses a lead-to-pad bonding method, reducing the manufacturing cost and processing difficulty of the infrared gas sensor.

[0046] The principle of this invention is as follows: The gas molecules in the optical chamber selectively absorb infrared light. Infrared light emitted from the infrared light source 11 is reflected by the periodic micro / nano structure 12 and then through the reflective film layer 3 before entering the infrared detector through the filter layer. When the infrared detector receives the absorbed infrared light, it converts it into a corresponding electrical signal output, thereby measuring the concentration of the gas. The purpose of this invention is to provide a wafer-level integrated micro-infrared gas sensor that utilizes the method of generating surface plasmon polaritons using periodic micro / nano structures to enhance the interaction between infrared light and gas, thereby improving the detection sensitivity of the infrared gas sensor within a small optical chamber.

[0047] In summary, unlike traditional discrete and integrated infrared gas sensors, this invention further reduces the sensor size through wafer-level integration while improving the sensor's sensitivity using surface-enhanced infrared absorption technology, thus achieving miniaturization and high sensitivity of the infrared gas sensor.

[0048] The term "constituting of" in describing a combination should include the identified elements, components, parts, or steps, as well as other elements, components, parts, or steps that do not substantially affect the essential novel features of the combination. The use of the terms "comprising" or "including" to describe combinations of elements, components, parts, or steps herein also contemplates embodiments that are essentially composed of such elements, components, parts, or steps. The use of the term "may" herein is intended to indicate that any described attribute included by "may" is optional.

[0049] Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The use of "a" or "an" to describe an element, component, part, or step does not imply the exclusion of other elements, components, parts, or steps.

[0050] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A miniature integrated infrared gas sensor chip, characterized in that, The device includes a first wafer (2) and a second wafer (8), which are connected by bonding to form an optical chamber (13); the surface of the second wafer (8) is covered with an insulating film layer (9), and an infrared light source (11) and an infrared detector are disposed above the insulating film layer (9); a vent hole (1) is opened above the first wafer (2); the inner wall of the optical chamber (13) is coated with a reflective film layer (3) to reflect the light beam emitted by the infrared light source (11); The optical air chamber (13) is provided with a periodic micro-nano structure (12); the periodic micro-nano structure (12) includes multiple micro-nano units arranged in an array.

2. The miniature integrated infrared gas sensor chip according to claim 1, characterized in that, The micro-nano unit is a cylinder, cone, prism or pyramid, and the arrangement pattern of the periodic micro-nano structure (12) is one or more combinations of rectangle, rhombus, hexagon, ellipse, circle or cross; the upper end of the periodic micro-nano structure (12) is connected to the reflective film layer (3), and the height of the periodic micro-nano structure (12) is 60%-80% of the height of the optical air cell (13).

3. The miniature integrated infrared gas sensor chip according to claim 1, characterized in that, The infrared detector includes a first infrared detector (5) and a second infrared detector (14). A first filter film (4) is disposed above the first infrared detector (5), and a second filter film (15) is disposed above the second infrared detector (14). The first filter film (4) and the second filter film (15) transmit infrared light with different wavelengths.

4. The miniature integrated infrared gas sensor chip according to claim 1, characterized in that, The infrared light source (11) is provided with a protective film layer (10), which is a SiO2 film layer.

5. A miniature integrated infrared gas sensor chip according to claim 1, characterized in that, The infrared light source (11) is a broadband or narrow-spectrum light source based on a MEMS micro heater. The micro heater is provided with a radiation layer, which is platinum black, carbon black or polycrystalline silicon.

6. A miniature integrated infrared gas sensor chip according to claim 1 or 5, characterized in that, The infrared detector is a MEMS thermopile chip, pyroelectric chip, photodiode, or light guide detector.

7. A miniature integrated infrared gas sensor chip according to claim 1, characterized in that, The periodic micro / nano structure (12) has a coating on its surface, and the coating material is one or a combination of Au, Ag, Cu and Al.

8. A miniature integrated infrared gas sensor chip according to claim 1, characterized in that, The second wafer (8) has a TSV via (6) inside, and the infrared light source (11) and the infrared detector are electrically connected to the electrode (7) on the lower surface of the second wafer (8) through the TSV via (6).

9. A miniature integrated infrared gas sensor chip according to claim 1, characterized in that, The insulating film layer (9) is provided with metal pads (16), which are located outside the first wafer (2) and are electrically connected to the infrared light source (11), the first infrared detector (5) and the second infrared detector (14) through metal wires on the insulating film layer.

10. A miniature integrated infrared gas sensor chip according to claim 1, characterized in that, The insulating film layer (9) is a composite film layer of SiO2-SiNx.

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