Infrared thermopile sensor and manufacturing method therefor

Abstract

An infrared thermopile sensor and a manufacturing method therefor. The infrared thermopile sensor is provided with an annular first trench in a substrate, and a heat conduction enhancement layer is provided in the first trench, the heat conduction enhancement layer being made of a conductive material; all thermocouple assemblies are arranged on an insulating layer and a support layer at intervals, and all the thermocouple assemblies extend from above the heat conduction enhancement layer towards the inner side of an inner ring. Additionally arranging the heat conduction enhancement layer improves the temperature stability of cold ends of the thermocouple assemblies, and achieves the effect of reflecting infrared rays, thus allowing cold junctions to be kept consistent with the environment temperature easier, facilitating the establishment of temperature gradients between hot ends and cold ends, and helping to improve the performance; the selection of material for the heat conduction enhancement layer makes the structure easy to implement, and only the cost of the heat conduction enhancement layer is increased, thus facilitating commercial mass production; an insulating layer is provided between the heat conduction enhancement layer and the thermocouple assemblies, and the insulating layer reduces flickering and noise of output signals of the infrared thermopile sensor.

Description

Infrared thermopile sensor and manufacturing method thereof Technical Field

[0001] The present invention relates to the technical field of temperature sensing, in particular to an infrared thermopile sensor and a manufacturing method thereof. Background Art

[0002] Infrared thermopile sensors are infrared thermal sensors. Their principle is to convert received infrared radiation into heat, then use the Seebeck effect to generate a thermoelectric potential between the start and end of at least one thermocouple pair connected in series. The intensity of the infrared radiation can be calculated by measuring the voltage signals at the start and end of all thermocouple pairs. For example, when there is only one thermocouple, the voltage signal generated by the Seebeck effect can be expressed as:

[0003] Among them, SA and SB are the Seebeck coefficients of the materials used for the two thermocouple arms of the thermocouple. When SA and SB are assumed to be temperature-invariant, V = (SA-SB) ΔT, where ΔT is the temperature difference between the two ends of the thermocouple. The infrared thermopile sensor is manufactured based on the MEMS (Micro-Electro-Mechanical System) process, and can also be combined with the MEMS process and the CMOS process. It is widely used in non-contact temperature measurement, NDIR gas analysis, thermal imaging and other applications. As can be seen from the above, thermopile sensors have the advantages of simple principle, simple and convenient use (i.e., no need for refrigeration, no need for chopper, no need for bias voltage, wide operating spectrum range, non-contact measurement), low cost (process compatible with CMOS process). Therefore, it occupies a very large share in the infrared sensor market.

[0004] While infrared thermopile sensors are primarily popular in temperature measurement, low-cost gas analysis, and low-resolution thermal imaging, they face strong competition in other niche applications. For example, pyroelectric detectors in motion detection and high-end gas analysis offer faster response and higher sensitivity. Microbolometer arrays and cooled photon detectors in thermal imaging offer higher precision and resolution. Therefore, improving the performance of infrared thermopile sensors has long been a focus of the industry.

[0005] Currently, considerable research has been conducted both domestically and internationally on improving the performance of infrared thermopile sensors. However, these studies have focused on developing high-infrared absorptivity materials, film systems, or structural designs, or optimizing device size and structure. The high-performance infrared thermopile sensors developed in these studies often suffer from high costs, limited practicality, and difficulties in mass production, hindering market acceptance.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to provide an infrared thermopile sensor and a manufacturing method thereof, which can solve the problems of high cost, insufficient practicality and difficulty in mass production of current high-performance infrared thermopile sensors, thus making them difficult to be accepted by the market.

[0008] In order to solve the above problems, the present invention provides an infrared thermopile sensor, comprising: a substrate, wherein a first annular groove is provided in the substrate, and a thermal conductivity enhancement layer is provided in the first groove, wherein the material of the thermal conductivity enhancement layer is a conductive material; a support layer, wherein the support layer covers the substrate inside the inner ring of the first groove; an insulating layer, wherein the insulating layer covers the thermal conductivity enhancement layer; a plurality of thermocouple assemblies, wherein all the thermocouple assemblies are arranged at intervals on the insulating layer and the support layer, and all the thermocouple assemblies extend from above the thermal conductivity enhancement layer toward the inside of the inner ring; and an absorption assembly, wherein the absorption assembly covers the support layer and all the thermocouple assemblies.

[0009] Optionally, the material of the thermal conductivity enhancement layer is Al.

[0010] Optionally, the thickness of the thermal conductivity enhancement layer is greater than 2 μm, the width of the thermal conductivity enhancement layer is greater than 10 μm, or the width of the thermal conductivity enhancement layer is greater than the cold junction width of the thermocouple assembly.

[0011] Optionally, the insulating layer is made of silicon carbide or aluminum nitride, in which case the insulating layer only covers the thermal conductivity enhancing layer; or the insulating layer is made of silicon oxide or silicon nitride, in which case the insulating layer covers the thermal conductivity enhancing layer and the support layer.

[0012] Optionally, the thermocouple assembly includes: a first thermocouple arm, located on the insulating layer and the support layer, and the first thermocouple arm extends from above the thermal conductivity enhancement layer toward the inner side of the inner ring; an intermediate dielectric layer, located on the first thermocouple arm; a second thermocouple arm, located on the intermediate dielectric layer; a connecting column, passing through the intermediate dielectric layer, and the side close to the first thermocouple arm is in contact with the first thermocouple arm, and the side close to the second thermocouple arm is in contact with the second thermocouple arm.

[0013] Furthermore, the absorption component includes: a polysilicon layer, located on the supporting layer and located on the inner side of all the first thermocouple arms, the polysilicon layer and the first thermocouple arms are arranged in contact, and the intermediate dielectric layer covers the polysilicon layer; an optical interference thermal guide layer, located on the supporting layer and located on the inner side of all the first thermocouple arms, and the polysilicon layer is arranged around the optical interference thermal guide layer; an infrared absorption layer, covering the optical interference thermal guide layer, the second thermocouple arms and the intermediate dielectric layer covering the polysilicon layer; and an enhanced absorption layer, covering the polysilicon layer and the infrared absorption layer above the optical interference thermal guide layer.

[0014] Furthermore, the first groove is a circular ring, an elliptical ring or a polygonal ring; the optical interference thermal guide layer is composed of a plurality of petal structures centered on the center position of the first groove, and the width of each petal structure gradually increases from the center position to the direction away from the center position.

[0015] Furthermore, the distance between the optical interference thermal guide layer and the nearby thermocouple assembly is less than 10 μm, and the thickness of the optical interference thermal guide layer is 100 nm to 1 μm.

[0016] Furthermore, the optical interference heat guide layer is made of metal material or polysilicon material.

[0017] Optionally, the substrate includes a front side and a back side that are relatively arranged, and a cavity is provided in the substrate on the inner side of the inner ring of the first groove, and the cavity is a through hole, which passes through the substrate and exposes the support layer on the front side, and the opening size of the cavity on the back side is the same as the inner ring width of the thermal conductivity enhancement layer, and the opening size of the cavity on the front side is smaller than the inner ring width of the first groove; or, the cavity is a blind hole, the cavity and the first groove are both located on the front side, and the support layer closes the opening of the cavity, and the depth of the first groove is smaller than the depth of the cavity, and the opening size of the cavity is smaller than the inner ring width of the first groove.

[0018] Furthermore, the distance between the thermal conductivity enhancement layer and the cavity is greater than 5 μm.

[0019] Furthermore, when the cavity is a blind hole, the absorption component above the cavity has a plurality of evenly distributed through holes, and the through holes pass through the support layer, the insulating layer and the absorption component.

[0020] On the other hand, the present invention provides a method for manufacturing an infrared thermopile sensor. The preparation of the infrared thermopile sensor includes the following steps: providing a substrate, wherein a first annular groove is formed in the substrate, and a support layer is formed on the substrate on the inner side of the inner ring of the first groove; forming a thermal conductivity enhancement layer and an insulating layer, wherein the thermal conductivity enhancement layer fills the first groove, and the insulating layer is located on the thermal conductivity enhancement layer, wherein the material of the thermal conductivity enhancement layer is a conductive material; forming a plurality of thermocouple assemblies and an absorption assembly, wherein all the thermocouple assemblies are arranged at intervals on the insulating layer and the support layer, and all the thermocouple assemblies extend from above the thermal conductivity enhancement layer toward the inner side of the inner ring, and the absorption assembly covers the support layer and all the thermocouple assemblies.

[0021] Optionally, after forming a plurality of thermocouple assemblies and an absorption assembly, the method further includes: forming a cavity in the substrate, wherein the cavity exposes the support layer.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The addition of a thermal conductivity enhancement layer improves the temperature stability of the cold junction of the thermocouple assembly and also reflects infrared rays, making it easier for the cold junction to maintain consistency with the ambient temperature. This facilitates the establishment of a temperature gradient between the hot and cold junctions, improves the response rate, and thus enhances the performance of the infrared thermopile sensor. Since conventional conductive materials are common (such as aluminum), the structure of the infrared thermopile sensor of the present invention is easy to implement, and only the cost of the thermal conductivity enhancement layer (which can be ignored) is added. Therefore, while the performance is significantly improved, the cost is almost increased, which is conducive to commercial large-scale production.

[0024] 2. An insulating layer is provided between the thermal conductivity enhancement layer and the thermocouple assembly, which can reduce the flicker noise of the output signal of the infrared thermopile sensor;

[0025] 3. The interference heat-guiding layer in the absorption component causes the reflected light to interfere with and couple with the incident light, thereby improving the infrared absorption capacity. In addition, the specific pattern of the light interference and heat-guiding layer allows it to simultaneously guide the heat flow, helping heat to gather toward the hot end of the thermocouple, reducing heat loss outside the thermocouple arm when the absorption area has uniform heat conduction and heat radiation. This means that under the same radiation intensity, the hot junction can have a higher and faster temperature rise, which is conducive to improving the response rate and response time.

[0026] 4. The thermal conductivity enhancement layer and the interference heat guide layer are conducive to providing a good electromagnetic environment for the sensor and reducing environmental noise. Because the stability of the ambient temperature is improved, the thermal noise will also be reduced to a certain extent, which is conducive to reducing the equivalent noise power and improving the detection rate.

[0027] 5. The manufacturing method of the infrared thermopile sensor is based on the CMOS process and does not require the addition of a mask. Only the steps of forming the first trench and filling the first trench are added. Therefore, the manufacturing cost is almost unchanged while the performance is significantly improved. It can be seen that the present invention has a higher cost-effectiveness and is conducive to commercial large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a schematic top view of an infrared thermopile sensor provided in Embodiment 1 of the present invention.

[0029] FIG2 is a schematic cross-sectional view of FIG1 along line AA'.

[0030] FIG3 is a schematic flow chart of a method for manufacturing an infrared thermopile sensor provided in the first embodiment of the present invention.

[0031] FIG4 is a schematic structural diagram of a substrate provided in Embodiment 1 of the present invention.

[0032] FIG5 is a schematic structural diagram of the first embodiment of the present invention after forming a thermal conductivity enhancement layer.

[0033] FIG6 is a schematic diagram of the structure after the N-type ion implantation process according to the first embodiment of the present invention.

[0034] FIG7 is a schematic diagram of the structure after forming a polysilicon layer according to the first embodiment of the present invention.

[0035] FIG8 is a schematic structural diagram of the first embodiment of the present invention after forming an intermediate dielectric layer.

[0036] FIG9 is a schematic structural diagram of the first embodiment of the present invention after the second thermocouple arm is formed.

[0037] FIG10 is a schematic diagram of a first shape of an optical interference heat guide layer according to an embodiment of the present invention.

[0038] FIG. 11 is a schematic diagram of a second shape of an optical interference heat guide layer according to an embodiment of the present invention.

[0039] FIG12 is a schematic structural diagram of the first embodiment of the present invention after forming the infrared absorption layer.

[0040] FIG13 is a schematic structural diagram of the first embodiment of the present invention after forming a thermal conductivity enhancement layer.

[0041] FIG14 is a schematic top view of an infrared thermopile sensor provided in the second embodiment of the present invention.

[0042] FIG15 is a cross-sectional schematic diagram of the second embodiment of the present invention, which is FIG14 along line AA′.

[0043] Among them, 100-substrate; 101-cavity; 110-support layer; 120-thermal conductivity enhancement layer; 130-insulating layer; 200-thermocouple assembly; 210-first thermocouple arm; 211-first opening; 220-connecting column; 230-second thermocouple arm; 240-intermediate dielectric layer; 241-second opening; 300-absorption assembly; 310-polysilicon layer; 320-optical interference thermal guide layer; 330-infrared absorption layer; 340-enhanced absorption layer; 400-through hole. DETAILED DESCRIPTION

[0044] The following is a further detailed description of an infrared thermopile sensor and its manufacturing method according to the present invention. The present invention will be described in more detail below with reference to the accompanying drawings, which illustrate preferred embodiments of the present invention. It should be understood that those skilled in the art may modify the present invention described herein while still achieving the beneficial effects of the present invention. Therefore, the following description should be understood as a general guideline for those skilled in the art and is not intended to limit the present invention.

[0045] For the sake of clarity, not all features of actual embodiments are described. In the following description, well-known functions and structures are not described in detail because they would obscure the present invention with unnecessary detail. It should be understood that in the development of any actual embodiment, numerous implementation details must be made to achieve the developer's specific goals, such as adapting from one embodiment to another to accommodate system or business constraints. Furthermore, it should be understood that such development work may be complex and time-consuming, but is nevertheless a routine undertaking for those skilled in the art.

[0046] In order to make the purpose and features of the present invention more obvious and easy to understand, the specific embodiments of the present invention are further described below with reference to the accompanying drawings. It should be noted that the drawings are all in a very simplified form and use non-precise ratios, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0047] In current research, both domestically and internationally, a common approach to improving the performance of infrared thermopile sensors is to treat the absorption region's surface (for example, by "blackening" it) to enhance infrared absorption efficiency. This is achieved by adding materials such as black silicon or metal black to the surface. Black silicon, due to its wide bandgap, limits its absorption wavelength range. While metal black offers high absorptivity, it requires materials, equipment, and processes not commonly used in standard CMOS processes, resulting in demanding manufacturing conditions and high costs. Other improved approaches, such as nanoforest structures leveraging the surface plasmon effect, also face numerous challenges, including complex manufacturing processes (multiple steps), high difficulty, high equipment costs, and poor reliability. Considering that the original, unimproved performance of infrared thermopile sensors has resulted in extremely low unit prices after significant capacity expansion and market competition, these approaches have struggled to gain market acceptance due to the limited performance improvements and significant cost increases associated with new materials and processes. Therefore, a technical solution is needed that can significantly improve the performance of infrared thermopile sensors while effectively controlling costs.

[0048] It is important to understand that because metal materials have higher thermal conductivity than silicon semiconductor materials, for example, aluminum, a common metal material, has a greater heat capacity, this means that infrared thermopile sensors with the same structure and size have better thermal conductivity and temperature stability. Since thermal conductivity is also related to the size of the structure, in one-dimensional flat wall heat conduction, the thermal conductivity rate can be expressed as Q = kAT / L, or Q = T / R, where k is the thermal conductivity of the structure, A is the flat wall area, L is the flat wall thickness, T is the temperature difference perpendicular to the flat wall, and R is the thermal resistance, R = kA / L. This shows that the thermal conductivity rate is inversely proportional to the thickness of the structure in the heat transfer direction and directly proportional to the cross-sectional area of ​​the structure. Therefore, the insulating film between the thermal conductivity enhancement layer and the cold end needs to be as thin as possible (i.e., to reduce the longitudinal thermal resistance), and the film layer between the two thermocouple arms should also be as thin as possible (i.e., to increase the lateral thermal resistance).

[0049] The output voltage V_S of an infrared thermopile sensor can be expressed as V_S = N(S_A - S_B)T, where N is the logarithm of the thermocouple assembly, S_A is the Seebeck coefficient of the material used for the first thermocouple arm, S_B is the Seebeck coefficient of the material used for the second thermocouple arm, and T is the average temperature difference. This expression shows that increasing the average temperature difference T between the hot and cold ends of the thermocouple assembly can directly improve the output signal of the infrared thermopile sensor. The responsivity R_s of an infrared thermopile sensor is the ratio of the signal output voltage V_S to the incident radiation power P, that is, R_s = V_s / P. In other words, an increase in the output signal of an infrared thermopile sensor represents an increase in responsivity. Furthermore, the equivalent noise power (NEP) of an infrared thermopile sensor is the radiation power when the output voltage V_S generated by the incident power P is exactly equal to the noise voltage V_nosie of the infrared thermopile sensor. It is defined as NEP = V_nosie / R_s, meaning that a smaller noise voltage leads to a smaller equivalent noise power. The detection rate D of the infrared thermopile sensor is defined as the inverse of the equivalent noise power NEP, that is, D = 1 / NEP, which means that a smaller noise voltage will lead to a higher detection rate.

[0050] Based on this, the present invention provides an infrared thermopile sensor, which includes a substrate, a first annular groove is provided in the substrate, a thermal conductivity enhancement layer is provided in the first groove, and a support layer, an insulating layer, a plurality of thermocouple assemblies and an absorption component are provided on the substrate, the support layer covers the substrate inside the inner ring of the first groove, the insulating layer covers the thermal conductivity enhancement layer, all the thermocouple assemblies are arranged at intervals on the insulating layer and the support layer, and all the thermocouple assemblies extend from above the thermal conductivity enhancement layer toward the inside of the inner ring, the absorption component covers the support layer and all the thermocouple assemblies, wherein the material of the thermal conductivity enhancement layer is a conductive material.

[0051] The present invention improves the temperature stability of the cold end of the thermocouple assembly through the thermal conductivity enhancement layer, and also has the function of reflecting infrared rays. This makes it easier for the cold junction (cold end) of the thermocouple assembly to maintain consistency with the ambient temperature, which is beneficial to establishing a temperature gradient between the hot and cold ends of the thermocouple assembly and improving the response rate, thereby improving the performance of the infrared thermopile sensor. Since there are many conventional materials in the conductive material (such as aluminum), the structure of the infrared thermopile sensor of the present invention is easy to implement, and only the cost of the thermal conductivity enhancement layer is increased (which can be ignored). Therefore, while the performance is significantly improved, there is almost no increase in cost, which is conducive to commercial large-scale production.

[0052] Example 1

[0053] As shown in Figures 1 and 2, this embodiment provides an infrared thermopile sensor, which includes a substrate 100. A first annular groove is provided in the substrate 100. A cavity 101 is provided in the substrate 100 on the inner side of the inner ring of the first groove. The cavity 101 is a through hole located inside the first groove. A thermal conductivity enhancement layer 120 is provided in the first groove. A support layer 110, an insulating layer 130, a plurality of thermocouple assemblies 200 and an absorption assembly 300 are provided on the substrate 100. The support layer 110 is located at The substrate 100 is positioned above the cavity 101 and covers the outside of the cavity 101 and the inside of the inner ring. The insulating layer 130 covers the thermal conductivity enhancing layer 120. All of the thermocouple assemblies 200 are spaced apart on the insulating layer 130 and the support layer 110, and all of the thermocouple assemblies 200 extend from above the thermal conductivity enhancing layer 120 toward the inside of the inner ring. The absorption assembly 300 covers the support layer 110 and all of the thermocouple assemblies 200. The thermal conductivity enhancing layer 120 is made of a conductive material. The thermocouple assemblies 200 have a cold end and a hot end along their extension direction. The cold end is located above the thermal conductivity enhancing layer 120, and the hot end is located inside the inner ring and connected to the absorption assembly 300.

[0054] The thermal conductivity enhancement layer 120 of this embodiment has high thermal conductivity and specific heat capacity, which can improve the temperature stability of the cold end (cold junction) of the thermocouple assembly 200. It also reflects infrared light, making it easier for the cold end of the thermocouple assembly 200 to maintain consistency with the ambient temperature, which facilitates the establishment of a gradient between the hot and cold end temperatures. This improves the performance of the infrared thermopile sensor without significantly increasing costs, making it easier to mass-produce. Furthermore, an insulating layer 130 is provided between the thermal conductivity enhancement layer 120 and the thermocouple assembly 200 to reduce flicker noise in the infrared thermopile sensor's output signal.

[0055] Specifically, the material of the substrate 100 can be single crystal silicon. The shape of the substrate 100 can be selected according to actual needs and can be square, rectangular or circular. The material and shape of the substrate 100 are not specifically limited in this embodiment.

[0056] The substrate 100 includes a front side and a back side that are opposite to each other. The cavity 101 passes through the substrate 100 . The opening size of the cavity 101 on the back side is the same as the inner ring width of the thermal conductivity enhancement layer 120 , and the opening size of the cavity 101 on the front side is smaller than the inner ring width of the thermal conductivity enhancement layer 120 .

[0057] A support layer 110 is provided on the front surface of the substrate 100. This support layer 110 covers the opening of the cavity 101 on the front surface, as well as the outer surface of the cavity 101 and the inner surface of the inner ring. This support layer 110 is used to support structures located thereon, such as the insulating layer 130, the thermocouple assembly 200, and the absorption assembly 300. The support layer 110 can be a silicon oxide layer, or a silicon oxide layer and a silicon nitride layer, with the silicon oxide layer located between the silicon nitride layer and the front surface. The thickness of the support layer 110 is 200 nm to 500 nm.

[0058] A first groove is provided on the front surface of the substrate 100. The first groove extends through the support layer 110, with the bottom located in the substrate 100. The first groove is annular, such as a rectangular ring, a circular ring, an elliptical ring, or another polygonal ring. The depth of the first groove is greater than 2 μm, and the width of the first groove is greater than 10 μm, preferably greater than the cold junction width h of the thermocouple assembly 200.

[0059] A thermal conductivity enhancement layer 120 is provided in the first groove, and the thermal conductivity enhancement layer 120 fills the first groove. The material of the thermal conductivity enhancement layer 120 is a conductive material, such as a metal material, specifically a commonly used CMOS metal such as Al, Ti, W, etc., and can also be a compound with high thermal conductivity, such as silicon carbide. Preferably, the material of the thermal conductivity enhancement layer 120 is Al. Compared with other conductive materials, the thermal conductivity and specific heat capacity of Al are higher, which means that Al has better thermal conductivity and temperature stability under the same structure and size, so that the thermal conductivity enhancement layer 120 can improve the cold end (cold junction) temperature stability of the thermocouple assembly 200, and also has the function of reflecting infrared rays, which makes it easier for the cold end of the thermocouple assembly 200 to be consistent with the ambient temperature, which is conducive to the establishment of a gradient between the hot end temperature and the cold end temperature, so as to improve the infrared thermopile sensor without significantly increasing the cost, and at the same time, it is easy to mass produce.

[0060] The thickness of the thermal conductivity enhancement layer 120 is greater than 2 μm, and the width (i.e., the inner ring width of the first groove) is greater than 10 μm. Preferably, the width of the thermal conductivity enhancement layer 120 is greater than the cold junction width h. The distance between the thermal conductivity enhancement layer 120 and the cavity 101 is greater than 5 μm.

[0061] Optionally, an adhesion-promoting film layer is further formed between the thermal conductivity enhancing layer 120 and the insulating layer 130 , and the adhesion-promoting film layer covers the thermal conductivity enhancing layer 120 to increase adhesion between the thermal conductivity enhancing layer 120 and the insulating layer 130 .

[0062] The insulating layer 130 can be made of a highly thermally conductive insulating material, such as undoped silicon carbide (SiC) or aluminum nitride (AlN). In this case, the thickness of the insulating layer 130 is 50 nm to 500 nm. Alternatively, the insulating layer 130 can be made of a conventional insulating material, such as silicon oxide or silicon nitride. Because the insulating layer 130 between the thermally conductive enhancement layer and the cold end needs to be as thin as possible (i.e., to reduce longitudinal thermal resistance), the thickness of the insulating layer 130 is 20 nm to 200 nm.

[0063] When the material of the insulating layer 130 is a high thermal conductivity insulating material, due to its small lateral thermal resistance, the insulating layer 130 only covers the adhesion film layer on the thermal conductivity enhancing layer 120; when the material of the insulating layer 130 is silicon oxide or silicon nitride, due to its large lateral thermal resistance and small longitudinal thermal resistance, the insulating layer 130 can cover the adhesion film layer on the thermal conductivity enhancing layer 120 and the support layer 110 on the inner side of the inner ring.

[0064] The thermocouple assemblies 200 are in an elongated strip shape and are provided in an even number of pairs. In this embodiment, there are four pairs of thermocouple assemblies 200, and the cold ends of each pair of thermocouple assemblies 200 are located at the intersection of two adjacent sides of the rectangular ring. In other embodiments, the cold ends of each pair of thermocouple assemblies 200 may be located on each side of the rectangular ring.

[0065] The thermocouple assembly 200 includes a first thermocouple arm 210, an intermediate dielectric layer 240, a connecting post 220, and a second thermocouple arm 230. The first thermocouple arm 210 is located on the insulating layer and the support layer. The first thermocouple arm 210, the intermediate dielectric layer 240, and the second thermocouple arm 230 are all elongated and stacked sequentially on the insulating layer 130. The connecting post 220 passes through the intermediate dielectric layer 240, and contacts the first thermocouple arm 210 on the side closest to the first thermocouple arm 210, and contacts the second thermocouple arm 230 on the side closest to the second thermocouple arm 230. The end of the first thermocouple arm 210 located above the thermal conductivity enhancement layer 120 is the cold end of the thermocouple assembly 200, while the ends of the first thermocouple arm 210 and the second thermocouple arm 230 away from the thermal conductivity enhancement layer 120 are the hot ends of the thermocouple assembly 200.

[0066] When the insulating layer 130 is made of a high thermal conductivity insulating material, the first thermocouple arm 210 is located on the insulating layer 130 and the support layer 110 ; when the insulating layer 130 is made of silicon oxide or silicon nitride, the first thermocouple arm 210 is located only on the insulating layer 130 .

[0067] The material of the first thermocouple arm 210 is polysilicon doped with N-type ions. In this case, the insulating layer 130 can reduce the flicker noise of the output signal of the infrared thermopile sensor. The thickness of the first thermocouple arm 210 is 300nm to 5μm. The material of the intermediate dielectric layer 240 is a low thermal conductivity insulating material, such as silicon oxide. Because the film layer between the two thermocouple arms should be as thin as possible (i.e., to increase lateral thermal resistance), the thickness of the intermediate dielectric layer 240 is 20nm to 500nm. The connecting column 220 serves as the interconnection line between the first thermocouple arm 210 and the second thermocouple arm 230. It needs to have good ohmic contact and can be a composite film structure of materials such as TiN / Ti / W. The material of the second thermocouple arm 230 can be metal (such as Al, Ti, W, etc.) or polysilicon doped with N-type ions. The thickness of the second thermocouple arm 230 is 100nm to 1μm.

[0068] The absorption component 300 includes a polysilicon layer 310, an optical interference heat guide layer 320, an infrared absorption layer 330 and an enhanced absorption layer 340. The polysilicon layer 310 and the optical interference heat guide layer 320 are both located on the insulating layer 130 or the supporting layer 110 (that is, when the insulating layer 130 is a high thermal conductivity insulating material, the polysilicon layer 310 and the optical interference heat guide layer 320 are both located on the supporting layer 110; when the insulating layer 130 is a silicon oxide or When silicon nitride is used, the polysilicon layer 310 and the optical interference thermal guide layer 320 are both located on the insulating layer 130. The polysilicon layer 310 and the optical interference thermal guide layer 320 are located on the inner side of all the thermocouple assemblies 200, and the polysilicon layer 310 is arranged around the optical interference thermal guide layer 320. The polysilicon layer 310 is in contact with the other end of the first thermocouple arm 210. In this case, the intermediate dielectric layer 240 also covers the polysilicon layer 310. The infrared absorption layer 330 covers the optical interference thermal guide layer 320, the second thermocouple arm 230, and the intermediate dielectric layer 240 on the polysilicon layer 310. The enhanced absorption layer 340 covers the infrared absorption layer 330 above the polysilicon layer 310 and the optical interference thermal guide layer 320.

[0069] The polysilicon layer 310 and the optical interference heat guiding layer 320 are disposed on the same layer, and the polysilicon layer 310 is located between the optical interference heat guiding layer 320 and the first thermocouple arm 210. Because the optical interference heat guiding layer 320 is located above the support layer 110 and below the infrared absorption layer 330, the optical interference heat guiding layer 320 requires a specific shape to achieve the best effect. Due to its high thermal conductivity and specific heat capacity, it can both collect and guide heat flow, helping heat to converge toward the hot end of the thermocouple assembly 200, thereby reducing heat loss caused by uniform heat conduction and heat radiation from the absorption assembly 300. Therefore, the optical interference thermal guiding layer 320 is composed of a plurality of petal structures centered on the center position of the first groove, and the width of each petal structure gradually increases from the center position to the direction away from the center position, such as the fan-shaped shape with the vertex at the center position as shown in Figure 10, the triangle with the vertex at the center position as shown in Figure 11, and other shapes that are narrow inside and wide outside, and the optical interference thermal guiding layer 320 is adjacent to the first thermocouple arm 210, that is, the petals are as close to the first thermocouple arm 210 as possible.

[0070] Therefore, the distance between each petal structure of the optical interference thermal guide layer 320 and the nearby thermocouple assembly 200 is less than 10 μm. Preferably, the distance between the optical interference thermal guide layer 320 and the first thermocouple arm 210 is less than 5 μm, and the smaller the better. This ensures that the optical interference thermal guide layer 320 is in close proximity to the first thermocouple arm 210 to avoid directing heat flow outside the hot end. The thickness of the optical interference thermal guide layer 320 is between 100 nm and 1 μm to avoid affecting the reflection effect due to excessive thickness or thinness.

[0071] The material of the optical interference thermal guide layer 320 can be a metal material (such as Al, Ti, W and other commonly used CMOS metals) or a high reflectivity material or film system (such as polycrystalline silicon, silicon carbide, all-dielectric reflective film). When the material of the optical interference thermal guide layer 320 is a metal material, Al is preferably used so that the reflected light can be coupled with the incident light to achieve the effect of enhancing the infrared absorption rate of the infrared absorption layer 330; the thermal conductivity and specific heat capacity of the metal material are high (among which, Al has higher thermal conductivity and specific heat capacity than other metals), so it has the function of collecting and guiding heat flow, which can help heat to gather to the hot end of the thermocouple assembly 200, reducing the heat loss generated by heat conduction and heat radiation of the absorption assembly 300.

[0072] The polysilicon layer 310 is an undoped polysilicon layer 310, and the thickness of the polysilicon layer 310 is the same as the thickness of the first thermocouple arm 210. The infrared absorption layer 330 can be a silicon nitride layer, or a composite film layer of silicon oxide and silicon nitride. The thickness of the infrared absorption layer 330 is greater than 1 μm. In other embodiments, the infrared absorption layer 330 can also be an enhanced absorption layer such as a blackening treatment or a nano-forest structure. The enhanced absorption layer 340 is used to reduce reflection, and its material can be any one or more of TiN, TiO2, SiN, SiO, SiO2, SiC, and Al2O3. The thickness of the enhanced absorption layer 340 is 20 nm to 50 nm.

[0073] As shown in FIG3 , this embodiment also provides a method for manufacturing an infrared thermopile sensor, which is based on existing CMOS processes and materials and is compatible with existing infrared thermopile sensor processes. The method for manufacturing an infrared thermopile sensor includes the following steps:

[0074] Step S11: providing a substrate 100, wherein a first annular groove is formed in the substrate 100, and a support layer 110 is formed on the substrate 100 inside the inner ring of the first groove;

[0075] Step S12: forming a thermal conductivity enhancing layer 120 and an insulating layer 130 , wherein the thermal conductivity enhancing layer 120 fills the first groove, and the insulating layer 130 is located on the thermal conductivity enhancing layer 120 , wherein the thermal conductivity enhancing layer 120 is made of a conductive material;

[0076] Step S13: forming a plurality of thermocouple assemblies 200 and an absorption assembly 300, wherein all the thermocouple assemblies 200 are spaced apart on the insulating layer 130 and the support layer 110, and all the thermocouple assemblies 200 extend from above the thermal conductivity enhancement layer 120 toward the inner side of the inner ring, and the absorption assembly 300 covers the support layer 110 and all the thermocouple assemblies 200.

[0077] The following describes in detail a method for manufacturing an infrared thermopile sensor provided by this embodiment with reference to FIG. 1 to FIG. 13 .

[0078] First, step S11 is performed to provide a substrate 100 . A first annular groove is formed in the substrate 100 . A support layer 110 is formed on the substrate 100 inside the inner ring of the first groove.

[0079] This step specifically includes:

[0080] As shown in FIG4 , a substrate 100 is first provided. The substrate 100 has a front side and a back side facing each other. Next, a support layer 110 is deposited on the front side using a PECVD or LPCVD process. The support layer 110 is a silicon oxide layer, or a combination of the silicon oxide layer and a silicon nitride layer. The thickness of the support layer 110 is 200 nm to 500 nm.

[0081] As shown in FIG5 , a first trench is then formed by etching. The first trench is an annular trench that penetrates the support layer 110 and stops etching in the substrate 100. The first trench serves as a window for forming the thermal conductivity enhancement layer 120. The first trench has a width greater than 10 μm and a depth greater than 2 μm.

[0082] Then, step S12 is performed to form a thermal conductivity enhancing layer 120 and an insulating layer 130 . The thermal conductivity enhancing layer 120 fills the first trench, and the insulating layer 130 is located on the thermal conductivity enhancing layer 120 . The thermal conductivity enhancing layer 120 is made of a conductive material.

[0083] This step specifically includes:

[0084] First, referring to Figure 5 , a conductive material is deposited on the surface of the support layer 110 and in the first trench. The excess conductive material on the surface of the support layer 110 and in the first trench is removed through an etching process to form a thermal conductivity enhancement layer 120. The thermal conductivity enhancement layer 120 has a width greater than 10 μm and a thickness greater than 2 μm. The material of the thermal conductivity enhancement layer 120 is commonly used in CMOS, such as Al, Ti, or W. It can also be a high-thermal-conductivity compound, such as silicon carbide. In this embodiment, the material of the thermal conductivity enhancement layer 120 is Al.

[0085] Optionally, an adhesion-enhancing film layer (not shown in the figure) is deposited on the thermal conductivity enhancing layer 120 to increase adhesion. The material of the adhesion-enhancing film layer may be TiN.

[0086] As shown in Figure 6 , when the insulating layer 130 is made of a highly thermally conductive insulating material, the insulating layer 130 is deposited only on the adhesion-enhancing film layer. When the insulating layer 130 is made of silicon oxide or silicon nitride, the insulating layer 130 is deposited on both the adhesion-enhancing film layer and the support layer 110. The thickness of the insulating layer 130 is 20 nm to 200 nm. In this embodiment, the insulating layer 130 is made of silicon oxide, so the insulating layer 130 is deposited on the thermal conductivity-enhancing layer 120 and the support layer 110.

[0087] As shown in Figures 6 to 13, step S13 is then performed to form multiple thermocouple assemblies 200 and an absorption assembly 300. All of the thermocouple assemblies 200 are spaced apart on the insulating layer 130 and the support layer 110, and all of the thermocouple assemblies 200 extend from above the thermal conductivity enhancement layer 120 toward the inner side of the inner ring. The absorption assembly 300 covers the support layer 110 and all of the thermocouple assemblies 200.

[0088] This step specifically includes:

[0089] First, referring to FIG. 6 , a polysilicon thin layer is deposited on the insulating layer 130 by using LPCVD, APCVD, RTCVD or PECVD. The thickness of the polysilicon thin layer is 300 nm to 5 μm.

[0090] Next, an N-type ion implantation process is performed in the region where the first thermocouple arm 210 is to be formed, so as to form the first thermocouple arm 210 .

[0091] As shown in FIG7 , an etching process is then performed on the non-injected polysilicon region inside the first thermocouple arm 210 to form a first opening 211. The first opening 211 exposes the insulating layer 130, and the first opening 211 is formed into a plurality of petal structures that are narrow inside and wide outside. The non-injected polysilicon region outside the first opening 211 forms a polysilicon layer 310.

[0092] As shown in FIG8 , an intermediate dielectric layer 240 is then formed on the first thermocouple arm 210 using a PECVD, RTCVD, or LPCVD process. The intermediate dielectric layer 240 covers the first thermocouple arm 210, the insulating layer 130, and the polysilicon layer 310. The intermediate dielectric layer 240 is made of silicon oxide or other low-thermal-conductivity insulating material. The thickness of the intermediate dielectric layer 240 is between 20 nm and 500 nm.

[0093] Next, the intermediate dielectric layer 240 is etched to expose the insulating layer 130 at the first opening 211 , and a second opening 241 is formed above the first thermocouple arm 210 . The second opening 241 exposes the first thermocouple arm 210 .

[0094] Next, a conductive material is filled in the second opening 241 , and then an etching process is performed to retain the conductive material filled in the first opening 211 to form a connecting pillar 220 .

[0095] When the material of the connecting pillar 220 is the same as the material filling the first opening 211, the etching process retains the conductive material filled in the second opening 241 and the conductive material filled in the second opening 241, thereby simultaneously forming the connecting pillar 220 and the optical interference heat guide layer 320. When the material of the connecting pillar 220 is different from the material filling the first opening 211, only the conductive material filled in the second opening 241 is included to form the connecting pillar 220. The connecting pillar 220 is formed in the same manner as the process for forming a plug in a CMOS process, for example, a composite film layer of materials such as TiN / Ti / W is formed.

[0096] As shown in FIG. 9 , metal or polysilicon is deposited on the intermediate dielectric layer 240 using a PVD or CVD process, and then the second thermocouple arm 230 is formed through an etching process.

[0097] When the material deposited on the intermediate dielectric layer 240 is the same as the material filling the first opening 211, for example, Al, the etching process retains the deposited material on the intermediate dielectric layer 240 and the material filling the first opening 211, thereby simultaneously forming the second thermocouple arm 230 and the optical interference thermal guide layer 320. When the material deposited on the intermediate dielectric layer 240 is different from the material filling the first opening 211, only the second thermocouple arm 230 is formed.

[0098] It should be noted that the material filling the first opening 211 can be the same as the material of the second thermocouple arm 230, or the same as the material of the connecting pillar 220. Of course, in other embodiments, the material filling the first opening 211 can also be different from the materials of both the second thermocouple arm 230 and the connecting pillar 220. In this case, a special step is required to fill the first opening 211 with material to form the optical interference thermal guide layer 320, and this step can be performed before depositing the intermediate dielectric layer 240.

[0099] As shown in Figure 12, an infrared absorption layer 330 is then deposited on the optical interference heat guiding layer 320, the second thermocouple arm 230, and the intermediate dielectric layer 240 on the polysilicon layer 310 through a deposition process. The infrared absorption layer 330 may be a silicon nitride layer or a composite film layer of silicon oxide and silicon nitride, employing a passivation layer process commonly used in CMOS processes. The infrared absorption layer 330 has a thickness greater than 1 μm.

[0100] As shown in FIG13 , an enhanced absorption layer 340 is then formed on the infrared absorption layer 330. The enhanced absorption layer 340 covers the infrared absorption layer 330 above the polysilicon layer 310 and the optical interference thermal guidance layer 320. The enhanced absorption layer 340 is used to reduce reflection and can be made of any one or more of TiN, TiO2, SiN, SiO, SiO2, SiC, and Al2O3. The thickness of the enhanced absorption layer 340 is 20 nm to 50 nm.

[0101] As shown in Figure 2, a cavity 101 is then formed in the substrate 100, and the cavity 101 exposes the support layer 110. Specifically, a mask plate for etching to form the thermal conductivity enhancement layer 120 is used, a patterned mask layer is formed on the back side, and the substrate 100 is etched from the back side using the patterned mask layer as a mask to form a cavity 101. The cavity 101 passes through the substrate 100 and exposes the support layer 110. The cavity 101 is located inside the inner ring of the first groove. The opening size of the cavity 101 on the back side is the same as the inner ring width of the thermal conductivity enhancement layer 120, and the opening size of the cavity 101 on the front side is smaller than the inner ring width of the thermal conductivity enhancement layer 120.

[0102] Example 2

[0103] As shown in Figures 13 and 14, compared with Example 1, the cavity 101 of this embodiment is a blind hole located on the inner side of the first groove, and the cavity 101 is arranged on the same side as the first groove. The opening size of the cavity 101 is smaller than the inner ring width of the first groove, and the depth of the first groove is smaller than the depth of the cavity 101.

[0104] The specific structure of the infrared thermopile sensor is as follows: the infrared thermopile sensor includes a substrate 100, a first annular groove is provided in the substrate 100, a cavity 101 is provided in the substrate 100 on the inner side of the inner ring of the first groove, the cavity 101 is a blind hole located inside the first groove, a thermal conductivity enhancement layer 120 is provided in the first groove, a support layer 110, an insulating layer 130, a plurality of thermocouple assemblies 200 and an absorption assembly 300 are provided on the substrate 100, the support layer 110 is located above the cavity 101 and closes the opening of the cavity 101, and also covers the outside of the cavity 101 and the substrate inside the inner ring. 100, the insulating layer 130 covers the thermal conductivity enhancement layer 120, all the thermocouple assemblies 200 are arranged at intervals on the insulating layer 130 and the support layer 110, and all the thermocouple assemblies 200 extend from above the thermal conductivity enhancement layer 120 toward the inside of the inner ring, the absorption assembly 300 covers the thermocouple assemblies 200 and the support layer 110, and the thermocouple assemblies 200 have a cold end and a hot end in the extension direction thereof, the cold end is located above the thermal conductivity enhancement layer 120, and the hot end is located inside the inner ring and is connected to the absorption assembly 300, wherein the material of the thermal conductivity enhancement layer 120 is a conductive material.

[0105] In order to form the cavity 101, a plurality of evenly distributed through holes 400 are provided in the absorption component 300 above the cavity 101, and the through holes 400 pass through the support layer 110, the insulating layer 130 and the absorption component 300, wherein in the layer where the polysilicon layer 310 and the optical interference thermal guiding layer 320 are located, the through holes 400 pass through the optical interference thermal guiding layer 320.

[0106] In the method for preparing the infrared thermopile sensor of this embodiment, a step of forming a through hole 400 is added before forming the cavity 101. Specifically, due to the different material selections for each structural layer, a step of forming a through hole in the corresponding layer is required when forming each structural layer on the front surface of the substrate 100. This allows the through hole 400, which exposes the front surface of the substrate 100, to be formed in the support layer 110, the insulating layer 130, and the absorption component 300. Specifically, the additional steps are: when forming the first groove, a first through hole is simultaneously formed in the support layer 110; when forming the optical interference thermal guide layer 320, an etching step is added to form a second through hole in the optical interference thermal guide layer 320. The second through hole is located above the first through hole, and the first through hole and the second through hole are connected.

[0107] When forming the infrared absorption layer 330 , an etching step is added to form a third through hole in the infrared absorption layer 330 . The third through hole is located above the second through hole, and the first through hole, the second through hole and the third through hole are connected in sequence.

[0108] When forming the enhanced absorption layer 340, an etching step is added to form a fourth through hole in the enhanced absorption layer 340, wherein the fourth through hole is located above the third through hole, and the first through hole, the second through hole, the third through hole and the fourth through hole are connected in sequence, and the first through hole, the second through hole, the third through hole and the fourth through hole constitute a through hole to pass through the support layer, the insulating layer and the through hole 400 of the absorption component.

[0109] Finally, after the through hole 400 is formed, the front surface of the substrate 100 is etched at the through hole 400 by a dry etching process or a wet etching process to form a cavity 101 in the substrate 100 inside the inner ring of the first trench.

[0110] In summary, the present invention provides an infrared thermopile sensor and a method for manufacturing the same. The present invention improves the temperature stability of the cold end through the thermal conductivity enhancement layer, while also reflecting infrared rays. This makes it easier for the cold junction to maintain consistency with the ambient temperature, facilitates the establishment of a temperature gradient between the hot and cold ends, and improves the response rate. Furthermore, the interference heat guiding layer in the absorption component of the present invention causes the reflected light to interfere with and couple with the incident light, thereby improving the infrared absorption capability. Furthermore, the specific pattern of the light interference and heat guiding layer allows them to simultaneously guide heat flow, helping heat to converge toward the thermocouple hot end and reducing heat loss outside the thermocouple arms when the absorption region has uniform heat conduction and heat radiation. This means that under the same radiation intensity, the hot junction can have a higher and faster temperature rise, which is beneficial for improving the response rate and response time. The thermal conductivity enhancement layer and the interference heat guiding layer help provide a good electromagnetic environment for the sensor and reduce environmental noise. Furthermore, due to the improved ambient temperature stability, thermal noise is also reduced to a certain extent, which is beneficial for reducing equivalent noise power and improving detection rate. The manufacturing method of the infrared thermopile sensor of the present invention is based on the MEMS process and is compatible with the CMOS process. It does not require the addition of a mask plate, and only adds the steps of forming the first groove and filling the first groove. Therefore, the manufacturing cost is almost unchanged, while the performance is significantly improved. It can be seen that the present invention has a higher cost-effectiveness and is conducive to commercial large-scale production.

[0111] In addition, it should be noted that, unless otherwise specified or indicated, the terms "first" and "second" in the specification are only used to distinguish the various components, elements, steps, etc. in the specification, and are not used to indicate the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0112] It is understood that although the present invention has been disclosed above with reference to preferred embodiments, the above embodiments are not intended to limit the present invention. For any person skilled in the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or to modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. An infrared thermopile sensor, characterized in that: include: A substrate, wherein a first annular groove is provided in the substrate, and a thermal conductivity enhancement layer is provided in the first groove, wherein the thermal conductivity enhancement layer is made of a conductive material; a support layer, the support layer covering the substrate inside the inner ring of the first groove; an insulating layer, the insulating layer covering the thermal conductivity enhancing layer; a plurality of thermocouple assemblies, all of which are arranged at intervals on the insulating layer and the supporting layer, and all of which extend from above the thermal conductivity enhancement layer toward the inner side of the inner ring; An absorption assembly covers the support layer and all of the thermocouple assemblies.

2. The infrared thermopile sensor according to claim 1, characterized in that: The material of the thermal conductivity enhancing layer is Al.

3. The infrared thermopile sensor according to claim 1, characterized in that: The thickness of the thermal conductivity enhancement layer is greater than 2 μm, the width of the thermal conductivity enhancement layer is greater than 10 μm, or the width of the thermal conductivity enhancement layer is greater than the cold junction width of the thermocouple assembly.

4. The infrared thermopile sensor according to claim 1, characterized in that: The material of the insulating layer is silicon carbide or aluminum nitride. In this case, the insulating layer only covers the thermal conductivity enhancement layer; or, The material of the insulating layer is silicon oxide or silicon nitride. At this time, the insulating layer covers the thermal conductivity enhancing layer and the supporting layer.

5. The infrared thermopile sensor according to claim 1, characterized in that: The thermocouple assembly comprises: A first thermocouple arm is located on the insulating layer and the supporting layer, and the first thermocouple arm extends from above the thermal conductivity enhancement layer toward the inner side of the inner ring; An intermediate dielectric layer, located on the first thermocouple arm; A second thermocouple arm is located on the intermediate dielectric layer; The connecting column passes through the intermediate medium layer, and a side close to the first thermocouple arm contacts the first thermocouple arm, and a side close to the second thermocouple arm contacts the second thermocouple arm.

6. The infrared thermopile sensor according to claim 5, characterized in that: The absorbent assembly comprises: a polysilicon layer, located on the support layer and located inside all the first thermocouple arms, the polysilicon layer and the first thermocouple arms are arranged in contact, and the intermediate dielectric layer covers the polysilicon layer; An optical interference heat guiding layer is located on the supporting layer and inside all the first thermocouple arms, and the polysilicon layer is arranged around the optical interference heat guiding layer; an infrared absorption layer, covering the optical interference heat guiding layer, the second thermocouple arm and the intermediate dielectric layer covering the polysilicon layer; The enhanced absorption layer covers the polysilicon layer and the infrared absorption layer above the optical interference heat guide layer.

7. The infrared thermopile sensor according to claim 6, characterized in that: The first groove is a circular ring, an elliptical ring or a polygonal ring; The optical interference heat guiding layer is composed of a plurality of petal structures centered at the central position of the first groove, and the width of each petal structure gradually increases in a direction away from the central position.

8. The infrared thermopile sensor according to claim 7, characterized in that: The distance between the optical interference thermal guide layer and the nearby thermocouple assembly is less than 10 μm, and the thickness of the optical interference thermal guide layer is 100 nm to 1 μm.

9. The infrared thermopile sensor according to claim 6, characterized in that: The material of the optical interference heat guide layer is metal material or polysilicon material.

10. The infrared thermopile sensor according to claim 1, characterized in that: The substrate comprises a front side and a back side which are arranged opposite to each other, and a cavity is provided in the substrate inside the inner ring of the first groove. The cavity is a through hole, which passes through the substrate and exposes the support layer on the front side. The opening size of the cavity on the back side is the same as the inner ring width of the thermal conductivity enhancement layer, and the opening size of the cavity on the front side is smaller than the inner ring width of the first groove.

11. The infrared thermopile sensor according to claim 1, characterized in that: The substrate comprises a front side and a back side which are arranged opposite to each other, and a cavity is provided in the substrate inside the inner ring of the first groove. The cavity is a blind hole, the cavity and the first groove are both located on the front surface, the support layer closes the opening of the cavity, and the depth of the first groove is less than the depth of the cavity. The opening size of the cavity is smaller than the inner ring width of the first groove.

12. The infrared thermopile sensor according to claim 10, characterized in that: The distance between the thermal conductivity enhancing layer and the cavity is greater than 5 μm.

13. The infrared thermopile sensor according to claim 11, characterized in that: The absorption component above the cavity is provided with a plurality of evenly distributed through holes, and the through holes penetrate the support layer, the insulating layer and the absorption component.

14. A method for manufacturing an infrared thermopile sensor, comprising preparing the infrared thermopile sensor according to any one of claims 1 to 13, characterized in that: The following steps are involved: Providing a substrate, wherein a first annular groove is formed in the substrate, and a support layer is formed on the substrate inside an inner ring of the first groove; forming a thermal conductivity enhancing layer and an insulating layer, wherein the thermal conductivity enhancing layer fills the first groove, and the insulating layer is located on the thermal conductivity enhancing layer, wherein the material of the thermal conductivity enhancing layer is a conductive material; A plurality of thermocouple assemblies and an absorption assembly are formed, all of the thermocouple assemblies are arranged at intervals on the insulating layer and the supporting layer, and all of the thermocouple assemblies extend from above the thermal conductivity enhancement layer toward the inner side of the inner ring, and the absorption assembly covers the supporting layer and all of the thermocouple assemblies.

15. The method for manufacturing an infrared thermopile sensor according to claim 14, characterized in that: After forming a plurality of thermocouple assemblies and an absorber assembly, the method further comprises: A cavity is formed in the substrate, the cavity exposing the support layer.

Images