An infrared thermopile detector and a method of manufacturing the same

Abstract

The application discloses an infrared thermoelectric detector and a manufacturing method thereof, and belongs to the technical field of temperature sensing. The infrared thermoelectric detector comprises a substrate, a first thermocouple layer, a sacrifice layer and a second thermocouple layer are sequentially arranged on the substrate, and a vacuum heat insulation cavity is arranged in the sacrifice layer. The manufacturing method of the infrared thermoelectric detector comprises the following steps: preparing the vacuum heat insulation cavity in the sacrifice layer; etching the sacrifice layer to form a plurality of standby groove structures and a plurality of micropore arrays, the micropore array is a plurality of holes arranged on the top surface or the bottom surface of each standby groove structure, and the micropore array and the standby groove structure form a communication structure; and in a vacuum environment, a filling layer is deposited in the sacrifice layer, the communication structure is not completely filled, and at least one vacuum cavity is formed. Through the infrared thermoelectric detector with the vacuum heat insulation cavity, the response rate and the detection rate of the thermoelectric detector are effectively improved, and the resolution and the sensitivity of the detection result in the laser power measurement application are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of temperature sensing, in particular to an infrared thermopile detector and a manufacturing method thereof. BACKGROUND

[0002] Laser technology has been widely used in various industries. The characteristic measurement and metrology of laser light source / beam are key technologies that affect application and safety. Laser radiation characteristic metrology technology belongs to optical metrology technology, which mainly uses laser energy radiation parameter and performance parameter test equipment for testing. Power and energy are commonly used as measurement parameters and are considered as the key to laser characteristic evaluation. Laser power meters used for laser power detection are widely used in fields including laser communication, laser medical treatment, industrial processing, and scientific research. According to the measurement principle, laser power meters can be divided into three types: the first type is a photoelectric type, which uses a photoelectric sensor to convert light energy into an electrical signal to represent the size of the received laser power; the second type is a pyroelectric type, which uses a pyroelectric sensor. The surface of the receiving surface of the crystal generates an electric charge due to temperature change, and then converts it into an electrical signal output. The strength of the electrical signal represents the size of the laser power; the third type is a thermoelectric type, which uses a thermoelectric sensor. Light energy is converted into heat, and then the heat is converted into an electrical signal to represent the size of the laser power.

[0003] Compared with other types of laser power meters, laser power meters using thermoelectric devices have the advantages of flat response spectrum, high saturation point, and insensitivity to the incident position and angle of the measured laser beam. However, they also have the disadvantages of long response time and large volume of power meters using ordinary thermoelectric devices.

[0004] Currently, infrared thermopile sensors based on MEMS technology are widely used in medical treatment, industrial control, environmental monitoring, military, and other fields due to their small size, light weight, low power consumption, and low price. Laser power meters using MEMS thermoelectric sensors have also attracted great attention from the industry. It is particularly emphasized that the use of MEMS thermoelectric devices can significantly improve the shortcomings of laser power meter devices in response time and volume caused by the use of ordinary thermoelectric devices.

[0005] An infrared thermopile detector is a non-cooled infrared detector based on the Seebeck effect. Response rate, detection rate, and response time are three main parameters for evaluating the performance of an infrared thermopile detector.

[0006] The expression of the response rate of an infrared thermopile detector is as follows:

[0007]

[0008] wherein, is the response rate, is the total thermal response output voltage, is the infrared light source radiation power. From the expression of the response rate, it can be seen that the total thermal response output voltage is greater, the response rate is greater.

[0009] The expression of the detection rate of the infrared thermoelectric detector is as follows:

[0010]

[0011] wherein, is the response rate, is the area of the infrared layer absorption region, is the test bandwidth, is the noise voltage, which can be expressed as:

[0012]

[0013] wherein, k is the Boltzmann constant, ; is the ambient temperature, is the test bandwidth, is the thermoelectric resistance.

[0014] As deduced above, the response rate and the detection rate of the infrared thermoelectric detector can be improved by increasing the total thermal response output voltage of the infrared thermoelectric detector.

[0015] The response time expression of the infrared thermoelectric detector is as follows:

[0016]

[0017] wherein, is the total heat capacity of the infrared thermoelectric detector, is the total thermal conductance of the infrared thermoelectric detector.

[0018] As described above, compared with other technical routes of laser power meters, the laser power meter based on the MEMS thermoelectric device has obvious advantages, so designing and developing a MEMS thermoelectric device with high detection rate, high response rate, high sensitivity and low noise is the key to realizing high-performance laser power measurement.

[0019] The working principle of the infrared thermoelectric detector is based on the Seebeck effect. When two materials that constitute a thermocouple form a closed loop, a temperature difference between two nodes will generate a voltage in the loop. The greater the temperature difference between the two nodes, the higher the voltage generated in the loop, the better the performance of the device, such as sensitivity, and the higher the response rate and detection rate. ​

[0020] In actual MEMS thermoelectric device design, the temperature difference between hot junction and cold junction can be increased by increasing the number of thermocouples, increasing the area of the infrared absorption layer absorption region, using an absorption material with high infrared absorption rate, a thermocouple material with low thermal conductivity and a dielectric layer material, and selecting a thermocouple material with a large difference in Seebeck coefficient to achieve the purpose of increasing the thermal response output voltage, thereby improving the performance of the infrared thermoelectric device.

[0021] The infrared thermoelectric detector with a single-plane (coplanar) thermocouple structure can increase the temperature difference by lengthening the length of a single thermocouple in the horizontal direction and increasing the number of thermocouple pairs, thereby obtaining a higher thermoelectric conversion voltage. However, by increasing the number and length of the thermocouple pairs in the plane, the area occupied by the MEMS infrared detection device will inevitably increase, and the cost performance of the device will decrease sharply.

[0022] Changing the single-layer coplanar thermocouple structure of the infrared thermoelectric detector to a double-layer thermocouple structure doubles the number of thermocouples without significantly changing the device area, which is an effective method to improve the performance of the infrared thermoelectric detector.

[0023] However, in the double-layer thermocouple structure, a composite dielectric layer is needed to separate the two layers of thermocouple materials. The composite dielectric layer mainly serves as support, insulation and thermal insulation. In existing technical solutions, the composite dielectric layer is usually composed of silicon nitride, silicon oxide or a mixed film layer of silicon nitride and silicon oxide. However, due to the high thermal conductivity of silicon nitride, silicon oxide or a mixed film layer of silicon nitride and silicon oxide, heat will still be transferred between the two layers of thermocouples, resulting in a decrease in the temperature difference between the hot junction and the cold junction, a decrease in the sensitivity of the device and a decrease in the resolution of the device.

[0024] It should be noted that the information disclosed in the background section of the present application is only intended to deepen the understanding of the general background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. SUMMARY

[0025] The present application aims to provide an infrared thermoelectric detector and a manufacturing method thereof, which solves the problem of heat transfer between the two layers of thermocouples by setting a vacuum thermal insulation cavity between the double-layer thermocouples, thereby improving the thermoelectric conversion efficiency. Further, to prepare the vacuum thermal insulation cavity, a spare groove structure with different apertures and a micropore array are introduced, and the vacuum thermal insulation cavity is formed by not completely filling the spare groove structure or the micropore array. This manufacturing method has lower cost and is compatible with the CMOS process.

[0026] To solve the above technical problems, the present application provides a manufacturing method of an infrared thermoelectric detector, which comprises:

[0027] A substrate is provided, and a first support layer, a first thermocouple layer and a sacrificial layer are sequentially formed on the substrate;

[0028] A vacuum insulation cavity is prepared in the sacrificial layer;

[0029] The sacrificial layer is etched to form a plurality of standby groove structures;

[0030] The sacrificial layer is etched to form a plurality of micropore arrays, which are a plurality of holes opened on the top surface or the bottom surface of each standby groove structure, and the micropore array and the standby groove structure form a communication structure;

[0031] In a vacuum environment, a filling layer is deposited in the sacrificial layer, and the communication structure is incompletely filled by using the difference in aperture between the micropore array and the standby groove structure, to form at least one vacuum cavity;

[0032] After the vacuum insulation cavity is formed, a second thermocouple layer is deposited on the top of the sacrificial layer.

[0033] Preferably, the micropore array is a plurality of holes opened on the bottom surface of each standby groove structure, and the process of forming the micropore array and the standby groove structure comprises:

[0034] The sacrificial layer is etched to form the standby groove structure;

[0035] The bottom of the standby groove structure is continuously etched to form the micropore array.

[0036] Preferably, after the micropore array is formed:

[0037] The filling layer is deposited in the standby groove structure by using a low-temperature chemical vapor deposition process, the top of the micropore array is blocked, and a vacuum cavity is formed in the micropore array;

[0038] A second support layer is deposited on the filling layer by using a plasma-enhanced chemical vapor deposition process;

[0039] Annealing treatment is performed to make the filling layer in a flow state, fill into the micropore array at the bottom, and form a vacuum cavity in the standby groove structure.

[0040] Preferably, after the filling layer is formed, a thin film layer is deposited on the filling layer before the second support layer is deposited, to accelerate the separation between the second support layer and the filling layer when the filling layer is annealed.

[0041] Preferably, the hole depth of the micropore array satisfies the following relationship:

[0042]

[0043] wherein, for the depth of the hole, for the depth of the spare groove structure, for the thickness of the sacrificial layer.

[0044] Preferably, the diameter of the holes of the micro-hole array satisfies the following relationship:

[0045]

[0046] wherein, is the diameter of the hole, is the depth of the hole.

[0047] Preferably, the volume between each of the spare groove structures and the micro-hole array of the bottom surface thereof satisfies:

[0048]

[0049] wherein, represents the total volume of the micro-hole array, represents the volume of the spare groove structure.

[0050] Preferably, the micro-hole array is a plurality of holes opened on the top surface of each of the spare groove structures, and the process of forming the micro-hole array and the spare groove structure comprises:

[0051] first etching the sacrificial layer to form a plurality of the micro-hole arrays;

[0052] then wet-etching the bottom of the micro-hole array until the sacrificial layer between adjacent holes is removed to form the spare groove structure.

[0053] Preferably, the filling layer is deposited to block the micro-hole array in a vacuum environment, and a vacuum cavity is formed in the spare groove structure.

[0054] Preferably, the height of the vacuum thermal insulation cavity is calculated in the following manner:

[0055] Total thermal conductance of the device structure :

[0056]

[0057] wherein, is the infrared radiation thermal conductance of the device absorption region, is the gas thermal conductance of the device, is the structural thermal conductance of the device, and is a function related to the height of the vacuum thermal insulation cavity:

[0058]

[0059] , , , These are the thermal conductivities of the first support layer, the first thermocouple layer, the second thermocouple layer, and the vacuum insulation cavity structure of the device's thermocouple region, respectively.

[0060] in:

[0061]

[0062] in The thermal conductivity of materials manufactured for each region. , and These represent the thickness, width, and length of each region, respectively.

[0063] responsivity of infrared thermopile detectors To match the overall thermal conductivity of the device structure The relevant convex function will affect the total thermal conductivity of the device structure. Substitute the responsivity of the infrared thermopile detector The expression is solved to obtain the response rate. The height of the vacuum insulation cavity at its maximum value.

[0064] An infrared thermopile detector is prepared using the manufacturing method of an infrared thermopile detector as described above.

[0065] An infrared thermopile detector includes a substrate, on which a first support layer, a first thermocouple layer, a sacrificial layer and a second thermocouple layer are sequentially disposed, and a vacuum insulation cavity is disposed in the sacrificial layer.

[0066] Preferably, the vacuum insulation cavity includes a filling layer, multiple spare slot structures, and multiple micropore arrays. The micropore array consists of several holes formed on the top or bottom surface of each spare slot structure. The micropore array and the spare slot structures form a connected structure. The filling layer does not completely fill the connected structure, forming at least one vacuum cavity.

[0067] Preferably, the micropore array consists of a plurality of holes formed on the bottom surface of each spare slot structure, and a second support layer is provided on the top of the spare slot structure for sealing the spare slot structure. The filling layer blocks the top of the micropore array and forms a vacuum cavity within the micropore array. The filling layer flows into the micropore array during annealing to form a vacuum cavity in the spare slot structure.

[0068] Preferably, the micropore array consists of a plurality of holes formed on the top surface of each spare slot structure, and the filling layer fills the micropore array to seal the spare slot structure and form a vacuum cavity within the spare slot structure.

[0069] The manufacturing method of the infrared thermoelectric detector provided by the application adds a vacuum heat insulation cavity structure compared with the prior art, and the infrared thermoelectric detector device structure with the vacuum heat insulation cavity is more excellent in heat insulation effect between the two thermocouple layers, can effectively improve the response rate and detection rate of the thermoelectric detector device, and further improve the resolution and sensitivity of the detection result in the laser power measurement application. Further, the aperture difference between the standby groove structure and the micropore array is fully utilized, and the existing mature process and material characteristics are utilized, so that the standby groove structure and the micropore array form a vacuum area for heat insulation due to incomplete filling, and other structures such as the second thermocouple layer are formed, the whole process production flow is optimized, compared with the process used for heat insulation by using a plurality of reflection films, the scheme is more simple, the process precision requirement of the equipment is low, the cost is lower, and the CMOS flow is compatible.

[0070] The infrared thermoelectric detector provided by the application belongs to the same inventive concept as the manufacturing method of the infrared thermoelectric detector provided by the application, so the infrared thermoelectric detector provided by the application at least has all the advantages of the manufacturing method of the infrared thermoelectric detector provided by the application, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0071] Those skilled in the art will understand that the provided drawings are used to better understand the application, and do not constitute any limitation on the scope of the application. Among them:

[0072] Figure 1 is a cross-sectional view of the infrared thermoelectric detector device with a vacuum heat insulation cavity between the double-layer thermocouple structures of the application;

[0073] Figure 2 is a top view of the infrared thermoelectric detector device with a vacuum heat insulation cavity between the double-layer thermocouple structures of the application;

[0074] Figure 3 is a partial top view of the vacuum heat insulation cavity structure between the double-layer thermocouple structures of the application;

[0075] Figure 4 is a partial top view of the standby groove and micropore array between the double-layer thermocouple structures of the application;

[0076] Figure 5 is a cross-sectional view of the substrate and the film layers such as the sacrificial layer thereon of an embodiment of the application;

[0077] Figure 6 is a partial cross-sectional view of the standby groove structure and the micropore array for preparing the vacuum heat insulation cavity of an embodiment of the application;

[0078] Figure 7is a partial perspective view of a spare groove structure and a micropore array of a vacuum insulation cavity prepared by an embodiment of the present application;

[0079] Figure 8 is a sectional view of a spare groove structure, a micropore array and an inner film layer between a double thermocouple structure of an embodiment of the present application;

[0080] Figure 9 is a sectional view of a vacuum insulation cavity and an inner film layer between a double thermocouple structure after annealing of an embodiment of the present application;

[0081] Figure 10 is a sectional view after forming a vacuum insulation cavity of an embodiment of the present application;

[0082] Figure 11 is a partial sectional view of a dry etching hole structure of a vacuum insulation cavity prepared between a double thermocouple structure of another embodiment of the present application;

[0083] Figure 12 is a partial top view of a dry etching hole structure of a vacuum insulation cavity prepared between a double thermocouple structure of another embodiment of the present application;

[0084] Figure 13 is a partial sectional view of a cavity after wet etching of a vacuum insulation cavity between a double thermocouple structure of another embodiment of the present application;

[0085] Figure 14 is a partial sectional view of a cavity after polycrystalline silicon deposition hole sealing of a vacuum insulation cavity prepared between a double thermocouple structure of another embodiment of the present application;

[0086] Figure 15 is a process flow chart of an embodiment of the present application.

[0087] In the drawings:

[0088] 100, substrate; 101, back cavity; 102, first support layer; 103, first thermocouple layer; 104, sacrificial layer; 105, vacuum insulation cavity; 1051, micropore array; 1052, spare groove structure; 1053, filling layer; 1054, film layer; 106, second support layer; 107, lead hole; 108, second thermocouple layer; 109, infrared absorption layer. DETAILED DESCRIPTION

[0089] To make the objectives, advantages and features of the present application clearer, the following further describes the present application in detail with reference to the drawings and specific embodiments. It should be noted that the drawings are very simplified and not drawn to scale, and are only used to facilitate and clarify the purpose of assisting the description of the embodiments of the present application. In addition, the structures shown in the drawings are often a part of the actual structures. In particular, the emphasis of each drawing is different, and sometimes different scales are used.

[0090] As used in the present application, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. The term "or" is generally employed in its sense of "and / or" unless the context clearly dictates otherwise. The term "plurality" is generally employed in its sense of "two or more" unless the context clearly dictates otherwise. The terms "first," "second," "third," etc. are used only to describe a particular one of the features and do not imply or suggest relative importance or imply a number of the features indicated. Thus, features defined with "first," "second," "third," etc. can explicitly or implicitly include one or at least two of the features. The term "proximal" generally refers to the end closer to the operator, and the term "distal" generally refers to the end closer to the patient. The terms "one end" and "the other end" and "proximal" and "distal" generally refer to two parts corresponding to each other, which include not only the end points, and the terms "mounting," "connecting," and "connection" should be interpreted broadly, for example, can be fixedly connected, or detachably connected, or integrated; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium; can be the internal communication or interaction relationship between two elements. In addition, as used in the present application, a component disposed in another component generally only indicates that there is a connection, coupling, cooperation or transmission relationship between the two components, and the two components can be directly or indirectly connected, coupled, cooperated or transmitted through an intermediate component, and cannot be understood as indicating or suggesting the spatial positional relationship between the two components, i.e. one component can be in any orientation inside, outside, above, below or one side of the other component, unless the context clearly indicates otherwise. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0091] The existing double-layer thermocouple structure technical scheme needs to separate two layers of thermoelectric material with a composite dielectric layer, which is composed of silicon nitride, silicon oxide or a mixed film layer of silicon nitride and silicon oxide. Due to the advantages of easy manufacturing and low cost, it is widely used in actual production. However, due to the high thermal conductivity of silicon nitride, silicon oxide or a mixed film layer of silicon nitride and silicon oxide, there is still a large amount of heat transfer between the two layers of thermocouples, which reduces the temperature difference between the hot junction and the cold junction, and further reduces the total voltage generated by the thermoelectric effect, resulting in insufficient sensitivity of the device.

[0092] In addition to the commonly used silicon nitride in production, the composite dielectric layer is composed of silicon oxide or a mixed film layer of silicon nitride and silicon oxide, and the skilled person will also alternately deposit metal (such as Al, Au) and dielectric layer (such as SiO2, Si3N4) between the two layers of thermocouples to form an infrared reflector (Bragg reflector), thereby reducing heat transfer by reflecting infrared radiation. The heat insulation of such a multilayer reflective film can significantly reduce the heat transfer by radiation in a high-temperature environment. However, this technical solution has a complex process, high precision requirements for the plating equipment, high angle dependence (the reflection efficiency is affected by the incident angle, and the film layer design needs to be optimized), low yield of batch production, and high cost.

[0093] Another common method in the production of infrared thermopile detectors is to fill low-thermal-conductivity solid materials between the thermocouple materials to reduce heat transfer. For example, aerogel, silica aerogel, or other low-thermal-conductivity composite materials are filled in the gap between the two layers of thermocouple materials by spin coating, spraying, or chemical vapor deposition to reduce heat transfer. However, this method has high requirements for the COMS process compatibility of the filling material. Moreover, the filling material such as aerogel is prone to aging, and after long-term use, it may shrink or crack, resulting in a decrease in heat insulation performance. In addition, the filling of solid materials increases the heat capacity of the device, reducing the response speed of the sensor.

[0094] To solve the problem of heat transfer between the double-layer thermocouple structure in the existing technical solutions, the structure of the infrared thermopile detector can be optimized to reduce the thermal conductivity and block the heat transfer between the double-layer thermocouple structure. Considering that vacuum environment can almost completely block heat conduction and eliminate the effect of gas molecules on heat conduction and convection, the present application proposes a structure that generates a vacuum insulation cavity between the double-layer thermocouple materials to replace the original composite dielectric layer. By optimizing the structure in the vertical direction, the heat conduction between the double-layer thermocouple structure is suppressed, and the thermoelectric conversion performance of the device is significantly improved.

[0095] Based on this, the core idea of the present application is to propose an infrared thermopile detector for laser power measurement and a manufacturing method thereof. The present application mainly aims at the problem of heat coupling between the double-layer thermocouple materials in the traditional double-layer thermocouple thermopile structure. A micro-mechanical vacuum insulation cavity structure is innovatively integrated between the two layers of thermocouple materials to maximize the suppression of heat transfer between the first thermocouple layer and the second thermocouple layer, improve the thermoelectric conversion efficiency, and further improve the sensitivity and other performances of the device. At the same time, the present application provides a manufacturing process step for integrating a micro-mechanical vacuum insulation cavity structure between the double-layer thermocouple structure in an infrared thermopile device, combining with the mature semiconductor manufacturing process, thereby providing a low-cost and mass-production manufacturing solution for infrared detectors and other applications.

[0096] Specifically, please refer to Figures 1-15 , which is a schematic diagram of an embodiment of the present application. As shown inFigure 15 As shown in the drawings, a manufacturing method of an infrared thermopile detector comprises:

[0097] Firstly, a substrate 100 is provided, and a first support layer 102, a first thermocouple layer 103 and a sacrificial layer 104 are sequentially formed on the substrate 100.

[0098] Secondly, a vacuum heat insulation cavity 105 is prepared in the sacrificial layer 104:

[0099] The sacrificial layer 104 is etched to form a plurality of standby groove structures 1052;

[0100] The sacrificial layer 104 is etched to form a plurality of micropore arrays 1051, which are a plurality of holes opened on the top surface or the bottom surface of each standby groove structure 1052, and the micropore array 1051 and the standby groove structure 1052 form a communication structure.

[0101] In a vacuum environment, a filling layer 1053 is deposited in the sacrificial layer 104, and the communication structure is not completely filled by utilizing the difference in aperture between the micropore array 1051 and the standby groove structure 1052, so as to form at least one vacuum cavity.

[0102] Finally, after the vacuum heat insulation cavity 105 is formed, a second thermocouple layer 108 is deposited on the top of the sacrificial layer 104.

[0103] The present application provides a technical solution which can reduce the heat transfer between the two layers of thermocouple materials, mainly by setting a vacuum cavity structure with excellent heat insulation performance between the double-layer thermocouple materials, to maximize the reduction of heat transfer between the double-layer thermocouple materials, increase the temperature difference between the hot junction and the cold junction, increase the thermal response output voltage, and improve the detection rate and response rate of the infrared thermopile detector.

[0104] To achieve the above technical effects, in addition to the conventional manufacturing steps of the infrared thermopile device, the technical solution of the present application constructs a vacuum heat insulation cavity 105 structure between the first thermocouple layer 103 and the second thermocouple layer 108. By fully utilizing the aperture difference between the standby groove structure 1052 and the micropore array 1051, and the existing mature process and material characteristics, the standby groove structure 1052 and the micropore array 1051 form a vacuum area for heat insulation due to incomplete filling, and then form the second thermocouple layer 108 and other structures, which optimizes the entire process production flow. Compared with the process used by the multilayer reflective film heat insulation, the scheme of the present application is more simplified, has low requirements on the process precision of the equipment, has lower cost and is compatible with the CMOS process.

[0105] In one embodiment, the first support layer 102 and the first thermocouple layer 103 are first formed on the substrate 100, and the first thermocouple layer 103 is etched to form a desired pattern. The vacuum insulation cavity 105 structure is then constructed above the etched first thermocouple layer 103. A layer of silicon dioxide is first deposited as a sacrificial layer 104 by chemical vapor deposition (CVD) or atomic layer deposition (ALD). The thickness of the sacrificial layer 104 determines the height of the final vacuum insulation cavity 105, which needs to match the depth of the spare groove structure 1052. Figure 5 The film layer structure is shown in FIG. 2.

[0106] In addition, considering that the thickness of the sacrificial layer 104 is large, there may be a case where the lead hole 107 is etched for a long time or is not etched. The preparation of the sacrificial layer 104 can be performed in steps. The thickness of the sacrificial layer 104 is monitored during the preparation process. When the thickness of the sacrificial layer 104 reaches 1 um, the lead hole 107 is generated at a specific position of the sacrificial layer 104 by photolithography or etching. Metal is deposited in the lead hole 107 as a lead. After the metal is deposited, the sacrificial layer 104 is then deposited. When the thickness of the sacrificial layer 104 reaches 1 um, the lead hole 107 is etched again, and metal leads are deposited in the lead hole 107. This process is repeated until the thickness of the sacrificial layer 104 reaches the target thickness.

[0107] In the preparation of the spare groove structure 1052 and the micropore array 1051 that are in communication with each other, the order of formation of the two is not specifically limited. The spare groove structure 1052 can be etched first, and then the micropore array 1051 can be etched at the bottom of the spare groove structure 1052 to form a structure in which the spare groove structure 1052 is on top and the micropore array 1051 is on the bottom. The structure can be referred to as the structure shown in FIG. 3. Figure 6 Conversely, the micropore array 1051 can be on top, and the spare groove structure 1052 can be on the bottom. The structure can be referred to as the structure shown in FIG. 4. Figure 7 Figure 12 Figure 13

[0108] It can be understood that, for the structure in which the micropore array 1051 is on top and the spare groove structure 1052 is on the bottom, the micropore array 1051 can be directly sealed in the spare groove structure 1052 to form a vacuum cavity. For the structure in which the spare groove structure 1052 is on top and the micropore array 1051 is on the bottom, the spare groove structure 1052 can be directly filled to form a vacuum cavity in the micropore array 1051. The filling layer 1053 is processed to become a flowable state and flows into the micropore array 1051 to form a vacuum cavity in the spare groove structure 1052.

[0109] ​​​It can be understood that the preparation of the standby groove structure 1052 needs to pay attention to the following technical points: first, under the premise of ensuring the miniaturization of the device, the vertical dimension of the vacuum heat insulation cavity 105 between the first and second thermocouple layers should be kept at a reasonable threshold, and a shallow structure is recommended to maintain the adiabatic effect while avoiding the incremental effect on the overall volume of the device. Second, the geometric configuration design of the top view projection can adopt rectangular, elliptical, trapezoidal and other basic forms, which can be adaptively adjusted and optimized according to the actual application scenario. The structure design strategy of the vacuum heat insulation cavity 105 ensures the heat insulation performance while providing sufficient structural design freedom for different packaging schemes.

[0110] wherein the depth of the vacuum heat insulation cavity 105 can be determined using the following mathematical model. In the design of an infrared MEMS thermopile device, the key design goal is to obtain a MEMS thermopile device with an optimal voltage response rate, i.e.:

[0111]

[0112] In the above formula, N is the number of thermocouple pairs of the thermopile device, is the difference between the Seebeck coefficients of the two materials, is the infrared absorption rate of the device's infrared absorption area, is the radiation power density of the infrared light source, is the area of the absorption area, is the total thermal conductance of the MEMS thermopile device.

[0113] The infrared radiation power density can be expressed as:

[0114]

[0115] wherein is the emission area of the infrared radiation source, is the distance between the radiation source and the surface of the thermopile device, is the root mean square conversion factor of the chopper, is the Stefan-Boltzmann constant (its value is ), is the emissivity of the black body; is the ambient temperature of the device; is the black body temperature.

[0116] The total thermal conductance of the thermopile device is composed of three parts: the structural thermal conductance of the device, the gas thermal conductance, and the infrared radiation thermal conductance of the absorption area, i.e.:

[0117]

[0118] wherein Thermal conductance of the structure of the device, Thermal conductance of the infrared radiation of the absorption region of the device, Thermal conductance of the gas of the device.

[0119] In particular, is calculated by the following formula:

[0120]

[0121] , , , Thermal conductance of the structure of the first support layer 102, the first thermocouple layer 103, the second thermocouple layer 108 and the vacuum insulation cavity 105 of the device, respectively,

[0122]

[0123] wherein is the thermal conductivity of the material of each region, , and are the thickness, width and length of each region, respectively. It should be noted that the calculation expression of the thermal conductance of the structure of the thermal isolation cavity contains the thickness parameter of the vacuum insulation cavity 105 .

[0124] Thermal conductance of the gas of the device is

[0125]

[0126] wherein is the thermal conductance coefficient of the gas, is the distance from the surface of the first support layer 102 of the device to the bottom of the back cavity of the device, is the distance from the surface of the thermocouple region of the device to the filter of the device.

[0127] Thermal conductance of the radiation of the absorption region of the device is

[0128]

[0129] is the infrared emissivity of the absorption region of the device.

[0130] In addition, the minimum process height limit must also be met, that is,

[0131]

[0132] wherein is the minimum thickness determined by the manufacturing process when manufacturing the vacuum insulation cavity 105.

[0133] Of course, the device size parameters should also meet the basic mechanical and mechanical strength constraints, the formula is not listed.

[0134] In summary, for a given size range of MEMS thermoelectric device, the determination of parameters including The optimization problem (objective function is the aforementioned The formula can be proved mathematically that the objective function is a convex function, so there is an optimal solution), through the above formula and additional design and process constraints, by using certain computer numerical and planning algorithm, the best parameters can be obtained.

[0135] In the following description of the embodiments, the target thickness of the vacuum insulation cavity 105 has been solved by using the optimization model proposed in this application, and is represented by .

[0136] In order to more clearly and clearly describe the infrared thermoelectric detector and manufacturing method for laser power measurement of the present application, the implementation method of the present application is further described in detail below in combination with the drawings and embodiments one and two. In addition, it should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present application in a schematic manner, and the drawings only show the components related to the present application, not the number, shape and size of the components when actually implemented. The actual implementation of each component type, number and proportion can be arbitrarily changed, and the component layout type can be more complex.

[0137]

Embodiment one

[0138] The following four-terminal beam double-layer thermocouple structure infrared thermoelectric detector is used to introduce a process implementation method of an infrared thermoelectric detector for laser power measurement. Here, the micro-hole array 1051 is taken as an example to illustrate a plurality of holes opened in the bottom surface of each standby groove structure 1052. The process of forming the micro-hole array 1051 and the standby groove structure 1052 includes: etching the sacrificial layer 104 to form the standby groove structure 1052, and continuing to etch the bottom of the standby groove structure 1052 to form the micro-hole array 1051, as shown in Figure 6 The thermocouple material is selected as N-type polysilicon and P-type polysilicon.

[0139] Step one: deposit the required base film layer structure on the substrate 100, as shown in Figure 5 . This step specifically includes:

[0140] A thin film of silicon oxide is deposited on the front side of the polished silicon substrate 100 as the first support layer 102, which can be prepared by PECVD or LPVCD technology. The thickness of the thin film of silicon oxide is controlled between 200 nm and 500 nm. In addition to silicon oxide, a thin mixture of silicon oxide and silicon nitride can also be used as the material of the first support layer 102. The first thermoelectric layer 103 is then deposited on the thin film of silicon oxide support layer, and the thickness can be controlled between 300 nm and 2 um. The optional processes include, but are not limited to, LPCVD, APCVD, RTCVD or PECVD, etc. In the present embodiment, the material of the first thermoelectric layer 103 is N-type polysilicon, but in addition to N-type polysilicon, other thermoelectric materials with high Seebeck coefficient and high figure of merit and compatible with CMOS process can also be selected. The polysilicon thin film is doped by ion implantation to make it conductive, and then the first thermoelectric layer 103 is etched to form a specific shape. At the same time, a window is etched in the first thermoelectric layer 103 as a metal lead hole 107.

[0141] Then, a layer of silicon dioxide is deposited on the first thermoelectric layer 103 which has completed etching of the first thermoelectric layer 103 and etching of the lead hole 107 by chemical vapor deposition (CVD) or atomic layer deposition (ALD) as a sacrificial layer 104. The thickness of the sacrificial layer 104 needs to be controlled between 2 um and 5 um. The material of the sacrificial layer 104 can be selected from silicon dioxide (SiO2), silicon nitride (Si3N4) or other low thermal conductivity insulating materials as the sacrificial layer 104 of the vacuum thermal insulation cavity 105.

[0142] Then, the metal lead hole 107 connecting the first thermoelectric layer 103 and the second thermoelectric layer 108 is etched on the sacrificial layer 104. When the sacrificial layer 104 is thick, the preparation and etching of the lead hole 107 can be performed in steps to prevent the time of etching the lead hole 107 from being too long or the lead hole 107 from not being etched.

[0143] Step two, forming a connected micro-hole array 1051 and a standby groove structure 1052 in the sacrificial layer 104, the cross section is as shown in Figure 6 and Figure 7 , and the top view is as shown in Figure 4 The present step specifically includes:

[0144] The standby groove structure 1052 is prepared on the surface of the sacrificial layer 104 by etching or photolithography process. The height of the standby groove structure 1052 is controlled between 0.5 um and 1.5 um. The etching of the standby groove structure 1052 can be selected by wet etching (using HF solution). Wet etching is suitable for shallow grooves, and the etching time needs to be controlled to prevent over-etching. After the preparation of the standby groove structure 1052 is completed, the micro-hole array 1051 is integrated and densely arranged at the bottom of the standby groove structure 1052 by photolithography or etching process. The spin coating method can be used for the photoresist coating process, which is suitable for photoresist coating of low aspect ratio structures.

[0145] The key parameters are controlled as follows: the lateral aperture of the micropore array 1051 is controlled in the range of 0.3um~1um, and the longitudinal pore depth is controlled in the range of 1um~3um. The pore depth of the micropore array 1051 satisfies the following constraint relationship:

[0146]

[0147] wherein, is the pore depth, is the backup groove structure depth, is the thickness of the sacrificial layer 104, the pore depth and the backup groove depth The ratio of the pore depth and the backup groove structure 1052 depth is preferably greater than 2:1, and if a larger cavity height after the annealing operation is desired, the ratio of the pore depth and the backup groove structure 1052 depth can be appropriately increased.

[0148] The lateral aperture of the micropore array 1051 satisfies the following constraint relationship:

[0149]

[0150] wherein, is the aperture, is the pore depth. According to the above constraint relationship, the ratio of the pore depth and the aperture in the technical solution of the present application is preferably not less than 3:1, and the ratio of the pore depth and the aperture can be appropriately adjusted according to actual needs in application.

[0151] The depth of the vacuum thermal insulation cavity 105 generated after the annealing operation is related to the density of the holes in the micropore array 1051 in addition to the depth of the backup groove structure 1052, the pore depth of the micropore array 1051, the ratio of the depth of the backup groove structure 1052 and the pore depth, the micropore aperture, the ratio of the micropore aperture and the micropore depth. The following adds a constraint condition of the volume sum of the micropore array 1051 and the volume of the backup groove structure 1052 to help technicians design the backup groove structure 1052 and the micropore array 1051 structure, and the volume between each backup groove structure 1052 and the micropore array 1051 on the bottom surface thereof satisfies:

[0152]

[0153] Herein represents the total volume of the micropore array 1051, The volume of the standby groove structure 1052. The total volume of the micropore array 1051 must be less than the volume of the standby groove structure 1052 and greater than half the volume of the standby groove, so as to ensure that the vacuum insulation cavity 105 formed is available, and the longitudinal volume of the device is not too large. In application, the ratio of the volume of the standby groove structure 1052 and the total volume of the micropore array 1051 can be adjusted according to actual conditions.

[0154] At the same time, it is necessary to ensure that the effective safety distance between the bottom of the micropore and the lower interface of the sacrificial layer 104 is reserved, which is about 200 nm. This process scheme realizes the reliable preparation of the high-precision micropore array 1051 by optimizing the matching of the photoresist coating mode and the structure parameters.

[0155] Step three: taking advantage of the characteristics of the filling layer 1053, which is solid at low temperature and liquid at high temperature, depositing the filling layer 1053 at low temperature, and forming a covering second support layer 106 on the filling layer 1053. By high-temperature annealing, the state of the filling layer 1053 changes, so as to fill into the micropore array 1051, and form a slightly larger and stable vacuum cavity in the standby groove structure 1052. Specifically, as shown in Figure 8 and Figure 9 After forming the micropore array 1051:

[0156] A low-temperature chemical vapor deposition process is used to deposit the filling layer 1053 in the standby groove structure 1052, block the top of the micropore array 1051, and form a vacuum cavity in the micropore array 1051;

[0157] A plasma-enhanced chemical vapor deposition process is used to deposit a second support layer 106 on the filling layer 1053;

[0158] Annealing treatment is performed to make the filling layer 1053 flow into the micropore array 1051 at the bottom, and form a vacuum cavity in the standby groove structure 1052.

[0159] In this step, the filling layer 1053 of the standby groove structure 1052 is grown by a low-temperature chemical vapor deposition (LTCVD) process. The thickness control of the filling layer 1053 of the standby groove structure 1052 follows the following constraint conditions:

[0160]

[0161] The depth of the standby groove structure 1052 is, The thickness of the filler layer is 1053. Recommended materials for the filler layer 1053 include borosilicate glass (BPSG), polyimide (PI), and benzocyclobutene (BCB). Other suitable materials can also be selected. The selected materials must meet the following conditions: 1) compatibility with CMOS process; 2) high pore filling efficiency (>95%); 3) low thermal conductivity (k≤1.0 W / m·K); 4) low curing temperature (<500℃).

[0162] More preferably, after the filling layer 1053 is formed and before the second support layer 106 is deposited, the spare trench structure 1052 completes gradient filling, and a thin film layer 1054 is deposited on the filling layer 1053. This film layer accelerates the separation between the second support layer 106 and the filling layer 1053 during annealing of the filling layer 1053. It should be noted that the thin film layer 1054 is generated using a low-temperature chemical vapor deposition (LTCVD) process, achieving a high-temperature peeling mechanism through the difference in material shrinkage rates. The main function of the thin film layer 1054 is to shrink and split during high-temperature annealing, allowing the filling layer 1053 to separate quickly from the support layer. The filling effect is mainly achieved by the filling layer 1053. The recommended thickness of the thin film layer 1054 is... That's fine. Recommended materials for thin film layer 1054 include polyimide (PI), benzocyclobutene (BCB), low-k dielectric materials (such as porous SiCOH), parylene, and polysiloxane. Other suitable materials can also be selected, but they must meet the following requirements: 1) compatibility with CMOS processes; 2) low thermal conductivity (k≤1.0 W / m·K); 3) low curing temperature (<500℃); 4) ability to shrink and split during high-temperature processing, with stress concentration during shrinkage. Thin film layer 1054 and filler layer 1053 can be made of two different materials, or the same material can be selected. For example, polyimide has excellent pore-filling ability and can shrink and split at high temperatures, making it easy to separate quickly from the subsequently generated support film at high temperatures. When polyimide is used as the filler material for the spare groove structure 1052, there is no need to generate an additional thin film layer 1054.

[0163] Next, as Figure 8 As shown, the previously generated filler layer 1053 and thin film layer 1054 are planarized by chemical mechanical polishing (CMP). Then, a low-stress dielectric support layer is constructed by plasma-enhanced chemical vapor deposition (PECVD). To distinguish it from the support layer below the first thermocouple layer 103, this dielectric support layer is called the second support layer 106, and the support layer below the first thermocouple material layer is called the first support layer 102.

[0164] The second support layer 106 serves a dual function of support and thermal insulation, and its thickness needs to be controlled between 200nm and 300nm. The material of the second support layer 106 can be silicon nitride or silicon oxide, or other materials with good insulation, high mechanical strength, low thermal conductivity, and compatibility with subsequent high-temperature processes. Windows are etched into the second support layer 106 to serve as lead holes 107 connecting the first thermocouple layer 103 and the second thermocouple layer 108.

[0165] Next, as Figure 9 As shown, a high-temperature annealing process is performed under specific atmospheric conditions. When the annealing temperature rises to a level where the filler layer 1053 can enter a flowable state, the thin film layer 1054 and the second support layer 106 are peeled off. During this process, a gap is formed between the thin film layer 1054 and the second support layer 106. This gap gradually increases during the annealing process. The filler layer 1053 achieves submicron-level pore structure filling through surface tension, finally forming the vacuum insulation cavity 105 described in this application. The distribution area of ​​the vacuum insulation cavity 105 is as follows: Figure 3 As shown.

[0166] To ensure that the thin film layer 1054 and the filling layer 1053 fully fill the pores and form a usable vacuum insulation cavity 105, there are certain requirements for the annealing time and annealing temperature. Generally, it needs to be done under specific atmospheric conditions ( A high-temperature annealing process is performed. When the annealing temperature rises to 1200℃±10℃, the filler material in the spare tank (with a melting temperature window of approximately 200℃-800℃) enters a fluid dynamic state, achieving submicron-level pore structure filling through surface tension. The special thin film layer 1054 shrinks and separates from the second support layer 106, creating a 0.5µm~1.5µm closed cavity structure. The annealing time is controlled at approximately 1.5±0.5 hours to ensure that the N+ / P+ doped polycrystalline silicon thermocouple material maintains lattice stability. In actual operation, the annealing time and annealing temperature can be slightly adjusted according to the depth of the pores and the depth of the vacuum insulation cavity 105.

[0167] The sealed cavity structure formed here is the key structure for solving the problem of interlayer thermal coupling in double-layer thermocouple materials. To optimize the responsivity and other performance characteristics of infrared thermopile devices, its cavity height is... The optimal parameters can be obtained through optimization design using the mathematical model described in the invention. The cavity height in this embodiment... The following expression should be satisfied:

[0168]

[0169] When using other processes to generate the vacuum insulation cavity 105 structure, as long as the calculated cavity height is obtained... It can ensure that the device performance is optimal and within the range of the process technology.

[0170] Step four, then in the vacuum insulation cavity 105 of the second support layer 106 above in turn deposited second thermocouple layer 108, metal layer (not shown), passivation layer (not shown), infrared absorption layer 109, and through lithography or etching process for the second thermocouple layer 108, metal layer, passivation layer, infrared absorption layer 109 patterning, namely.

[0171] In this step, continue to form a lead hole 107 in the deposition of the contact hole metal as the first thermocouple layer 103 and the second thermocouple layer 108 between the lead. The deposition of the second thermocouple layer 108, the second thermocouple layer 108 in the embodiment is selected P polysilicon, but also can select other thermocouple material. The deposition thickness of the second thermocouple layer 108 needs to be controlled in 100 nm ~ 1 um, can use PCD or CVD process. Lithography of the second thermocouple layer 108, and the N type polysilicon strip etched out before form a thermocouple pair structure. Continue to etch the window as the lead hole 107 connecting the first thermocouple layer 103 and the second thermocouple layer 108 on the second thermocouple layer 108.

[0172] Then, depositing metal lead, connecting the first thermocouple layer 103 and the second thermocouple layer 108, the second thermocouple layer 108 and the first thermocouple layer 103 together constitute a thermocouple. After the whole wafer is deposited on the passivation layer (not shown), the thickness of the passivation layer can be controlled between 400 nm ~ 1 um.

[0173] Then, depositing infrared absorption layer 109, the material of the infrared absorption layer 109 can be selected from silicon oxide or silicon oxide and silicon nitride composite film, the thickness of the infrared absorption layer 109 needs to be greater than 1 um; windowing on the passivation layer, leaving the wire bonding pad. Deposition of the mask layer (optional material silicon oxide, etc.) on the back of the substrate 100, and patterning, then etching the substrate 100, forming a back cavity 101, can be selected by wet or dry process. Finally form the infrared thermopile detector as shown in Figure 1 and Figure 2 .

[0174]

Example two

[0175] The following provides another method to prepare the vacuum insulation cavity 105 structure between the double layer thermocouple structure, the process steps are different from the steps two and three in example one, in the preparation of the vacuum insulation cavity 105 structure between the double layer thermocouple structure can also be used in the following steps two and three instead of the steps two and three in example one.

[0176] Step two, etching the sacrificial layer 104 to form a plurality of the micro hole array 1051, such as Figure 11 and Figure 12As shown, the back wet etching of the bottom of the micropore array 1051 is performed until the sacrificial layer 104 between adjacent pores is removed, forming the spare groove structure 1052, as shown. Figure 13

[0177] The micropore array 1051 is formed on the surface of the sacrificial layer 104 by dry etching, and the etching depth of the pore structure needs to be controlled. The depth of the pore structure must comply with the following constraints:

[0178]

[0179]

[0180] Herein, is the depth of the pore structure, is the thickness of the sacrificial layer 104, is the safety distance from the bottom of the pore structure to the lower surface of the sacrificial layer 104.

[0181] Herein, the pore diameter of the micropore array 1051 formed on the upper surface of the sacrificial layer 104 needs to meet the following conditions:

[0182]

[0183] wherein, is the pore diameter, is the pore depth.

[0184] In a vacuum environment, a poly-silicon layer is deposited by an LPCVD process to seal the through-hole, forming a hermetic cavity. The height of the final cavity is , and the height of the cavity complies with the following constraints:

[0185]

[0186] Herein, is the depth of the pore structure, is the thickness of the sacrificial layer 104, is the distance from the top of the formed vacuum cavity to the upper surface of the sacrificial layer 104.

[0187] The sacrificial layer 104 is selectively etched by using an anisotropic etchant (such as a diluted HF solution), and the lateral etching is achieved through the bottom of the hole until the sacrificial layer 104 between adjacent pores is completely removed, forming a continuous cavity structure. It should be noted that in this embodiment, Figure 13 and Figure 14 are only schematic diagrams and do not represent the effect of the non-90° vertical sidewall formed when etching a wafer with different crystal orientations.

[0188] ​Step three, the material of the filling layer 1053 is polysilicon, in a vacuum environment, the filling layer 1053 is deposited to seal the micro-hole array 1051, and a vacuum cavity is formed in the standby groove structure 1052, as shown in Figure 14 .

[0189] Specifically, in a vacuum environment, the polysilicon is deposited by the LPCVD process to seal the through hole and form the air-tight cavity.

[0190] Different from the embodiment one, in which the filling layer 1053 is deposited and then the high-temperature flowable property of the filling layer 1053 is used to form the vacuum cavity in the standby groove structure 1052, in the embodiment two, the positional relationship between the standby groove structure 1052 and the micro-hole array 1051 is changed, the polysilicon is deposited by the LPCVD process to seal the micro-hole array 1051 on the upper part, and the polysilicon after sealing the through hole and the sacrificial layer 104 above the vacuum cavity jointly serve as the second support layer 106 above the cavity, the scheme of the embodiment two does not need to separately deposit the second support layer 106 for sealing, compared with the infrared thermopile detector of the prior art and the scheme of the embodiment one, the structure and the process steps are simplified.

[0191] In addition, based on the same technical concept, as Figures 1 to 2 , the application also provides an infrared thermopile detector prepared by the manufacturing method of the infrared thermopile detector of the above-mentioned embodiments.

[0192] More preferably, the application provides an infrared thermopile detector, which comprises a substrate 100, wherein the substrate 100 is sequentially provided with a first support layer 102, a first thermocouple layer 103, a sacrificial layer 104, and a second thermocouple layer 108, and the sacrificial layer 104 is provided with a vacuum heat-insulating cavity 105.

[0193] The vacuum heat-insulating cavity 105 comprises a filling layer 1053, a plurality of standby groove structures 1052, and a plurality of micro-hole arrays 1051, the micro-hole array 1051 is a plurality of holes arranged on the top surface or the bottom surface of each standby groove structure 1052, the micro-hole array 1051 and the standby groove structure 1052 form a communication structure, and the filling layer 1053 does not completely fill the communication structure to form at least one vacuum cavity.

[0194] The vacuum part of the vacuum heat-insulating cavity 105 is realized by the incomplete filling of the filling layer 1053, and it can be understood that the structure in which the standby groove structure 1052 is on the upper part and the micro-hole array 1051 is on the lower part can be referred to as Figure 6 and Figure 7 , and vice versa, the structure in which the micro-hole array 1051 is on the upper part and the standby groove structure 1052 is on the lower part can be referred to as Figure 12 and Figure 13It can be understood that, for the structure of the micropore array 1051 on the top and the spare groove structure 1052 on the bottom, the micropore array 1051 can be directly sealed in the spare groove structure 1052 to form a vacuum cavity when filling; and for the structure of the spare groove structure 1052 on the top and the micropore array 1051 on the bottom, the filling layer 1053 is formed and the spare groove structure 1052 is sealed, and the filling layer 1053 is further processed to form a vacuum cavity in the spare groove structure 1052.

[0195] Specifically, the micropore array 1051 is a plurality of holes opened on the top surface of each spare groove structure 1052, and the second support layer 106 is arranged on the top of the spare groove structure 1052 to seal the spare groove structure 1052, wherein the filling layer 1053 seals the top of the micropore array 1051 and forms a vacuum cavity in the micropore array 1051, and the filling layer 1053 flows into the micropore array 1051 when annealing to form a vacuum cavity in the spare groove structure 1052.

[0196] Through the above embodiment one, the micropore array 1051 on the bottom and the spare groove structure 1052 on the top can be realized, and the filling layer 1053 flows into the micropore array 1051 when annealing to form a vacuum cavity with a relatively uniform height in the spare groove structure 1052, because the filling layer 1053 is in a solid state at a low temperature and in a flowing state at a high temperature.

[0197] The first support layer 102 is further arranged between the substrate 100 and the sacrificial layer 104 to support and insulate heat, and the lead hole 107 is further arranged in the sacrificial layer 104 to deposit metal to connect the upper and lower thermocouple layers, and the second thermocouple layer 108 and the infrared absorption layer 109 are further arranged above the second support layer 106, and other size relationships and implementation processes of the spare groove structure 1052 and the micropore array 1051 are the same as those in the embodiment one, which will not be described here.

[0198] Specifically, the micropore array 1051 is a plurality of holes opened on the top surface of each spare groove structure 1052, and the filling layer 1053 is filled in the micropore array 1051 to seal the spare groove structure 1052 and form a vacuum cavity in the spare groove structure 1052.

[0199] Through the above embodiment two, the micropore array 1051 on the top and the spare groove structure 1052 on the bottom can be realized, the bottom of the micropore array 1051 is etched to form the spare groove structure 1052 after the micropore array 1051 is formed, the filling layer 1053 is filled into the micropore array 1051 on the top, the spare groove structure 1052 is sealed, and a vacuum cavity with a relatively uniform height is formed.

[0200] The top of the sacrifice layer 104 does not need to be blocked by the second support layer 106, and the second thermocouple layer 108 can be directly arranged on the sacrifice layer 104, and then the lead hole 107, the infrared absorption layer 109 and other conventional structures are arranged. For the size relationship of the standby groove structure 1052 and the micropore array 1051, the implementation process is described in Embodiment 2, and will not be repeated here.

[0201] As shown in Figure 1 , an infrared thermopile detector for laser power measurement of the application includes a single crystal silicon substrate 100, a back cavity 101, a first support layer 102, a first thermocouple layer 103, a vacuum insulation cavity 105, a second support layer 106, a lead hole 107, a second thermocouple layer 108 and an infrared absorption layer 109. Figure 1 As shown in Figure 2 , the cross-sectional structure diagram along the A-A' direction is shown in Figure 2 , the infrared absorption layer 109 is located in the center area of the substrate 100, and the vacuum insulation cavity 105 is distributed below the infrared absorption layer 109 and the second thermocouple layer 108, as shown in Figure 3 , the second thermocouple layer 108 and the lead hole 107 are arranged below the infrared absorption layer 109, the infrared absorption layer 109 is arranged above the hot end of the second thermocouple layer 108, and a plurality of second thermocouple layers 108 are arranged circumferentially along the edge of the infrared absorption layer 109. The application mainly aims at the problem of thermal coupling between the double-layer thermocouple material layers in the traditional double-layer thermocouple thermopile structure, and innovatively integrates a micromechanical vacuum insulation cavity structure between the two thermocouple material layers. To maximize the heat transfer between the first thermocouple layer 103 and the second thermocouple layer 108, reduce heat loss, improve thermoelectric conversion efficiency, and improve the sensitivity and other performance of the device.

[0202] The above description is only a description of the preferred embodiments of the application, and does not limit the scope of the application. Any modification or modification made by a person skilled in the art based on the above disclosure is within the protection scope of the technical solution of the application.

Claims

1. A method for manufacturing an infrared thermopile detector, characterized in that, include: A substrate is provided, on which a first support layer, a first thermocouple layer and a sacrificial layer are sequentially formed; A vacuum insulation cavity is prepared within the sacrificial layer: The sacrificial layer is etched to form multiple spare trench structures; The sacrificial layer is etched to form a plurality of micropore arrays, wherein the micropore array consists of several holes formed on the top or bottom surface of each spare slot structure, and the micropore array and the spare slot structure form a connected structure. In a vacuum environment, a filling layer is deposited into the sacrificial layer, and the interconnected structure is not completely filled by utilizing the pore size difference between the micropore array and the spare groove structure to form at least one vacuum cavity. After the vacuum insulation cavity is formed, a second thermocouple layer is deposited on top of the sacrificial layer.

2. The method for manufacturing an infrared thermopile detector according to claim 1, characterized in that, The micropore array consists of several holes formed on the bottom surface of each spare slot structure. The process for forming the micropore array and the spare slot structure includes: First, the sacrificial layer is etched to form the spare trench structure; Continue etching the bottom of the spare groove structure to form the micropore array.

3. The method for manufacturing an infrared thermopile detector according to claim 2, characterized in that, After the micropore array is formed: The filling layer is deposited into the spare tank structure using a low-temperature chemical vapor deposition process to seal the top of the micropore array and form a vacuum cavity within the micropore array; A second support layer is deposited on the filler layer using a plasma-enhanced chemical vapor deposition process. Annealing is performed to make the filling layer flowable, filling the micropore array at the bottom and forming a vacuum cavity in the spare slot structure.

4. The method for manufacturing an infrared thermopile detector according to claim 3, characterized in that, After the filling layer is formed and before the second support layer is deposited, a thin film layer is also deposited on the filling layer to accelerate the separation between the second support layer and the filling layer during the annealing of the filling layer.

5. The method for manufacturing an infrared thermopile detector according to claim 2, characterized in that, The pore depth of the micropore array satisfies the following relationship: in, For hole depth, For the depth of the spare slot structure, For the thickness of the sacrificial layer.

6. The method for manufacturing an infrared thermopile detector according to claim 2, characterized in that, The pore sizes of the micropore array satisfy the following relationship: in, For aperture, The depth of the hole.

7. The method for manufacturing an infrared thermopile detector according to claim 2, characterized in that, The volume between each of the aforementioned spare slot structures and the micropore array on its bottom surface satisfies: in, Represents the total volume of the micropore array. This represents the volume of the spare slot structure.

8. The method for manufacturing an infrared thermopile detector according to claim 1, characterized in that, The micropore array consists of several holes formed on the top surface of each spare slot structure. The process for forming the micropore array and the spare slot structure includes: First, the sacrificial layer is etched to form a plurality of the micropore array; The bottom of the micro-hole array is then wet-etched until the sacrificial layer between adjacent holes is removed, forming the spare trench structure.

9. The method for manufacturing an infrared thermopile detector according to claim 8, characterized in that, In a vacuum environment, the filling layer is deposited to seal the micropore array, forming a vacuum cavity in the spare tank structure.

10. A method for manufacturing an infrared thermopile detector according to any one of claims 1-9, characterized in that, The height of the vacuum insulation cavity is calculated using the following method: Total thermal conductivity of computing device structure : in, For infrared radiation thermal conductivity in the absorption region of the device, For the gas thermal conductivity of the device, The structural thermal conductivity of the device is a function of the height of the vacuum insulation cavity. , , , These are the thermal conductivities of the first support layer, the first thermocouple layer, the second thermocouple layer, and the vacuum insulation cavity structure of the device's thermocouple region, respectively. in: in The thermal conductivity of materials manufactured for each region. , and These represent the thickness, width, and length of each region, respectively. responsivity of infrared thermopile detectors To match the overall thermal conductivity of the device structure The relevant convex function will affect the total thermal conductivity of the device structure. Substitute the responsivity of the infrared thermopile detector The expression is solved to obtain the response rate. The height of the vacuum insulation cavity at its maximum value.

11. An infrared thermopile detector, characterized in that, It is prepared using the manufacturing method of the infrared thermopile detector as described in any one of claims 1-10.

12. An infrared thermopile detector, characterized in that, The device includes a substrate on which a first support layer, a first thermocouple layer, a sacrificial layer, and a second thermocouple layer are sequentially disposed. A vacuum insulation cavity is disposed in the sacrificial layer. The vacuum insulation cavity includes a filling layer, multiple spare slot structures, and multiple micropore arrays. The micropore array consists of several holes formed on the top or bottom surface of each spare slot structure. The micropore array and the spare slot structures form a connected structure. The filling layer does not completely fill the connected structure, forming at least one vacuum cavity.

13. The infrared thermopile detector according to claim 12, characterized in that, The micropore array consists of several holes formed on the bottom surface of each spare slot structure. A second support layer is provided on the top of the spare slot structure to seal the spare slot structure. The filling layer blocks the top of the micropore array and forms a vacuum cavity within the micropore array. The filling layer flows into the micropore array during annealing to form a vacuum cavity in the spare slot structure.

14. The infrared thermopile detector according to claim 12, characterized in that, The micropore array consists of several holes formed on the top surface of each spare slot structure. The filling layer fills the micropore array to seal the spare slot structure and form a vacuum cavity within the spare slot structure.

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