Infrared thermosensitive detector and preparation method thereof

Abstract

The invention provides an infrared thermosensitive detector and a preparation method thereof. The infrared thermosensitive detector comprises a substrate, a first metal layer, a first manganese cobalt nickel oxide layer, a second metal layer, a second manganese cobalt nickel oxide layer and a third metal layer. Wherein the first metal layer is stacked on one surface of the substrate; the first nickel cobalt manganese oxide layer is arranged on one side, far away from the substrate, of the first metal layer; the second metal layer is stacked on one surface, far away from the substrate, of the first manganese cobalt nickel oxide layer; the second manganese cobalt nickel oxide layer is laminated on one surface, far away from the substrate, of the second metal layer; the third metal layer is stacked on one surface, far away from the substrate, of the second manganese cobalt nickel oxide layer; and an air layer or a vacuum layer is arranged between the first metal layer and the first manganese cobalt nickel oxide layer. The average absorptivity of the infrared thermosensitive detector in the range of 8-12 microns is 35-95%, and the infrared thermosensitive detector is low in thermal conductivity and high in device sensitivity.

Description

Technical Field

[0001] The present application relates to the field of infrared detection technology, and particularly, to an infrared thermosensitive detector and a preparation method thereof. Background Art

[0002] Manganese cobalt nickel oxide (Mn-Co-Ni-O, MCNO) thermosensitive material is a thermosensitive detection material with excellent negative temperature coefficient of resistance, and can be used to manufacture uncooled infrared detectors.

[0003] However, since the absorption coefficient of the spinel structure oxide material in the atmospheric infrared transparent window band is very small, the average absorption rate of the device in the 8-12 μm band is usually less than 30%. Therefore, traditional methods usually improve its absorption from two aspects to ensure the infrared light absorption efficiency and response sensitivity of the device: on the one hand, increasing the film thickness to improve the infrared absorption of the sensitive element; on the other hand, coating a black paint coating or a gold black film layer on the surface of the device to improve the absorption of the device. In addition, the preparation method of the chemical solution method of manganese cobalt nickel oxide material has a relatively high synthesis temperature, and a high-temperature resistant oxide substrate (for example, alumina) is required for the production of the film layer, resulting in a relatively large thermal conductivity of the device (about 10 -3 ~10 -4 W / K order of magnitude), thereby making the detection sensitivity level of the device relatively low (≤10 8 cm·Hz 0.5 / W). Summary of the Invention

[0004] An object of an embodiment of the present invention is to provide an infrared thermosensitive detector and a preparation method thereof.

[0005] In a first aspect, an embodiment of the present invention provides an infrared thermosensitive detector, which includes a substrate, a first metal layer, a first manganese cobalt nickel oxide layer, a second metal layer, a second manganese cobalt nickel oxide layer, and a third metal layer. Among them, the first metal layer is stacked on one surface of the substrate; the first nickel cobalt manganese oxide layer is disposed on a side of the first metal layer away from the substrate; the second metal layer is stacked on one surface of the first manganese cobalt nickel oxide layer away from the substrate; the second manganese cobalt nickel oxide layer is stacked on one surface of the second metal layer away from the substrate; the third metal layer is stacked on one surface of the second manganese cobalt nickel oxide layer away from the substrate; an air layer or a vacuum layer is provided between the first metal layer and the first manganese cobalt nickel oxide layer.

[0006] Optionally, the first manganese cobalt nickel oxide layer includes a first part and a second part, the first part is parallel to the substrate, and the second part is located on both sides of the first part for supporting the first part.

[0007] Optionally, calcium fluoride is coated on a surface of the first manganese cobalt nickel oxide layer close to the first metal layer.

[0008] Optionally, the second metal layer includes a plurality of first squares arranged in an array. Each first square has a side length dimension of 5 to 5.4 μm and a thickness of 0.05 to 0.1 μm. The interval between two adjacent first squares is 10 to 10.5 μm. The third metal layer includes a plurality of second squares arranged in an array. Each second square has a side length dimension of 2.5 to 4 μm and a thickness of 0.05 to 0.1 μm. Among them, the orthographic projection of the plurality of second squares on the surface of the substrate coincides with the orthographic projection of the plurality of first squares.

[0009] In a second aspect, an embodiment of the present invention provides a method for manufacturing the above infrared thermal detector. The method includes providing a substrate; preparing a first metal layer on one side of the substrate using a first preparation method; preparing a sacrificial layer on the side of the first metal layer away from the substrate using a second preparation method; preparing a first manganese cobalt nickel oxide layer on the side of the sacrificial layer away from the substrate using a third preparation method; preparing a second metal layer on the side of the first manganese cobalt nickel oxide layer away from the substrate using a first preparation method; preparing a second manganese cobalt nickel oxide layer on the side of the second metal layer away from the substrate using a third preparation method; preparing a third metal layer on the side of the second manganese cobalt nickel oxide layer away from the substrate using a first preparation method; and using wet etching to release the sacrificial layer to obtain the infrared thermal detector.

[0010] Optionally, the method further includes preparing a calcium fluoride thin film layer on the side of the sacrificial layer away from the substrate using a fourth preparation method before preparing the first manganese cobalt nickel oxide layer on the side of the sacrificial layer away from the substrate. The calcium fluoride thin film layer covers the first surface and the second side surface of the sacrificial layer.

[0011] Optionally, the fourth preparation method includes ultraviolet lithography and room-temperature magnetron sputtering deposition method. The thickness of the calcium fluoride thin film layer is 40 to 60 nm.

[0012] Optionally, the first preparation method includes ultraviolet lithography and dual ion beam sputtering method. The second preparation method includes room-temperature magnetron sputtering deposition method, ultraviolet lithography, and wet etching. The third preparation method includes high-temperature magnetron sputtering deposition method, and the high temperature is 300 to 450 °C.

[0013] Optionally, the side length dimension of the first metal layer is 50 to 150 μm, and the thickness is 0.15 to 0.4 μm. The side length dimension of the sacrificial layer is 56 to 162 μm, and the thickness is 1.5 to 2.5 μm. The thickness of the first manganese cobalt nickel oxide layer is 2.8 to 3.2 μm. The thickness of the second manganese cobalt nickel oxide layer is 1.4 to 1.6 μm.

[0014] Optionally, the method includes setting a protective layer on the surfaces of the first manganese cobalt nickel oxide layer and the second manganese cobalt nickel oxide layer using ultraviolet lithography before using wet etching to release the sacrificial layer to obtain the infrared thermal detector.

[0015] Through the above technical solutions, the present application provides an infrared thermosensitive detector and a preparation method thereof. The infrared thermosensitive detector in the present application has a strong magnetic resonance absorption structure of metal layer - air layer (or vacuum layer) - manganese cobalt nickel oxide layer - metal layer array - manganese cobalt nickel oxide layer - metal layer array, which can improve its infrared absorption in the range of 8 - 12 μm, and the average absorption rate is 35 - 95%; moreover, the presence of the air layer (or vacuum layer) reduces the thermal conductivity of the device and improves the sensitivity of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification, and are used to explain the present invention together with the following specific embodiments, but do not constitute a limitation to the present invention. In the drawings: Figure 1 is a front view structure diagram of an infrared thermosensitive detector provided by an exemplary embodiment of the present application; Figure 2 is a top view structure diagram of an infrared thermosensitive detector provided by an exemplary embodiment of the present application; Figure 3 is a schematic flow chart of a method for preparing an infrared thermosensitive detector provided by an exemplary embodiment of the present application; Figure 4 is a schematic diagram of the process for preparing an infrared thermosensitive detector provided by an exemplary embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0018] Manganese cobalt nickel oxide thermosensitive material is a thermosensitive detection material with excellent negative resistance temperature coefficient. In recent years, some progress has been made in the magnetron sputtering preparation of large-area uniform manganese cobalt nickel oxide thin films, the characterization of the infrared optical properties of the materials, and the development and characterization of wide-band infrared thermosensitive detectors. Manganese cobalt nickel oxide materials can be used to make infrared uncooled detectors. However, due to the small absorption coefficient of spinel structure oxide materials in the atmospheric infrared transparent window band, the average absorption rate of the device in the 8 - 12 μm band is usually less than 30%. Therefore, how to improve the infrared absorption of the device is very important. In addition, the preparation method of the chemical solution method of manganese cobalt nickel oxide materials has a relatively high synthesis temperature and requires a high-temperature resistant oxide substrate (for example, alumina) for film layer production, and a microbridge structure substrate based on silicon technology cannot be used, which makes the thermal conductivity of the device relatively large (about 10 -3 ~10-4 W / K magnitude), which is more than three orders of magnitude higher than the thermal conductivity of the microbridge structure device, resulting in a relatively low detection sensitivity level of the device (≤10 8 cm·Hz 0.5 / W). In some cases, when fabricating a manganese cobalt nickel oxide microbridge structure device, if a manganese cobalt nickel oxide material with a better spinel structure is to be prepared, its growth temperature needs to be set at 400 °C or higher. Therefore, it is difficult to use a polyimide sacrificial layer to fabricate a manganese cobalt nickel oxide microbridge structure device. Accordingly, the present application provides an infrared thermal detector and a preparation method thereof, which have a lower thermal conductivity and can improve the infrared absorption in the range of 8-12 μm.

[0019] Figure 1 is a front view structural diagram of an infrared thermal detector provided by an exemplary embodiment of the present application. Figure 2 is a top view structural diagram of an infrared thermal detector provided by an exemplary embodiment of the present application. As Figure 1 and Figure 2 shown, the infrared thermal detector includes a substrate 1, a first metal layer 2, a calcium fluoride thin film layer 4, a first manganese cobalt nickel oxide layer (first MCNO layer) 5, a second metal layer 6, a second manganese cobalt nickel oxide layer (second MCNO layer) 7, and a third metal layer 8.

[0020] The substrate 1 can be formed of at least one material selected from silicon, sapphire, silicon carbide, and gallium arsenide. In this embodiment, the substrate 1 is sapphire.

[0021] The first metal layer 2 is stacked on one surface of the substrate 1. The first metal layer 2 can be at least one of chromium gold (Cr / Au), platinum gold (Pt / Au), and titanium gold (Ti / Au). In this embodiment, the first metal layer 2 is Cr / Au. Among them, the role of chromium is to increase the adhesion between gold and the substrate. Gold has a good reflection effect on infrared. In some embodiments, the first metal layer 2 can be referred to as the first metal reflection layer.

[0022] The first manganese cobalt nickel oxide layer 5 is disposed on the side of the first metal layer 2 away from the substrate 1. An air layer or a vacuum layer is provided between the first manganese cobalt nickel oxide layer 5 and the first metal layer 2. The first manganese cobalt nickel oxide layer 5 includes a first portion 51 and a second portion 52. The first portion 51 is parallel to the substrate and is used for absorbing infrared light waves. The second portion 52 is located on both sides of the first portion 51 and is used for supporting the first portion 51. As Figure 1 can be seen, the first manganese cobalt nickel oxide layer 5 forms a microbridge structure. A calcium fluoride (i.e., the calcium fluoride thin film layer 4) is coated on the surface of the first manganese cobalt nickel oxide layer 5 close to the first metal layer 2. The calcium fluoride thin film layer 4 has strong corrosion resistance and is used to protect the first manganese cobalt nickel oxide layer 5 to prevent it from being corroded by hydrofluoric acid.

[0023] The second metal layer 6 is stacked on a surface of the first manganese cobalt nickel oxide layer 5 away from the substrate 1. The second metal layer 6 can be at least one of chromium gold (Cr / Au), platinum gold (Pt / Au), and titanium gold (Ti / Au). In this embodiment, the second metal layer 6 is Cr / Au. The second metal layer 6 includes a plurality of first squares arranged in an array. Among them, the side length dimension of each first square is 5-5.4 μm, the thickness is 0.05-0.1 μm, and the interval between two adjacent first squares is 10-10.5 μm. In this embodiment, the side length dimension of the first square is 5.2 μm, the thickness is 0.1 μm, and the interval between two adjacent first squares is 10 μm.

[0024] The second manganese cobalt nickel oxide layer 7 is stacked on a surface of the second metal layer 6 away from the substrate 1. The second nickel cobalt manganese oxide layer 7 is parallel to the substrate and is used to absorb infrared light waves.

[0025] The third metal layer 8 is stacked on a surface of the second manganese cobalt nickel oxide layer 7 away from the substrate 1. The third metal layer 8 is titanium gold (Ti / Au). The third metal layer 8 includes a plurality of second squares arranged in an array. The side length dimension of each second square is 2.5-4 μm, the thickness is 0.05-0.1 μm, and the orthographic projection of the plurality of second squares on the surface of the substrate 1 coincides with the orthographic projection of the plurality of first squares. In this embodiment, the side length dimension of the second square is 2.5 μm and the thickness is 0.1 μm.

[0026] As Figure 1 and Figure 2 shown, the infrared thermal detector further includes a cross alignment reticle 3, an external electrode 9, and an electrode lead 10. The cross alignment reticle 3 is used for alignment during the manufacturing process, and the cross alignment reticle 3 is formed on the substrate 1. The external electrode 9 is formed on the outer surface of the second part 51 of the first manganese cobalt nickel oxide layer 5. The electrode lead 10 is connected to the external electrode 9. The external electrode 9 is connected to an external readout circuit or an A / D converter through the electrode lead 10, and then the signal is output.

[0027] In some embodiments, the infrared thermal detector further includes a shielding tube shell, and the infrared thermal detector is placed on the copper sheet of the shielding tube shell.

[0028] The infrared thermal detector provided by the embodiment of the present application has a strong magnetic resonance absorption structure of metal layer-air layer (or vacuum layer)-manganese cobalt nickel oxide layer-metal layer array-manganese cobalt nickel oxide layer-metal layer array, which can improve its infrared absorption in the range of 8-12 μm, and the average absorption rate is 35-95%. Specifically, the absorption structure composed of the first metal layer 2, the first manganese cobalt nickel oxide layer 5 and the second metal layer 6 can provide magnetic resonance absorption peaks at 9-10.5 μm and 11-12 μm; the absorption structure composed of the second metal layer 6 and the third metal layer 7 can provide magnetic resonance absorption peaks at 8-9 μm and 10.5-11.5 μm. Through the longitudinal laminated structure design, the two groups of absorption peaks can be superimposed to cover the wide-band absorption peak of 8-12 μm. In addition, the presence of the air layer (or vacuum layer) reduces the thermal conductivity of the device and improves the sensitivity of the device.

[0029] Figure 3 is a schematic flowchart of a method for manufacturing an infrared thermal detector provided by an exemplary embodiment of the present application. Figure 4 is a schematic diagram of the process for manufacturing an infrared thermal detector provided by an exemplary embodiment of the present application. The following combines Figure 3 and Figure 4 to give an exemplary illustration of the method for manufacturing an infrared thermal detector.

[0030] S310, provide a substrate.

[0031] Select a sapphire substrate 1 with a thickness of 0.25-0.5 mm, clean it with an organic solvent (such as acetone, ethanol, etc.) to remove surface impurities, then rinse it with deionized water and dry it with high-purity nitrogen.

[0032] S320, prepare a first metal layer on one side of the substrate by using a first preparation method.

[0033] Prepare a first metal layer 2 on the substrate 1. Use ultraviolet lithography and dual ion beam sputtering methods to prepare a first metal layer with a side length dimension of 50-150 μm and a thickness of 0.15-0.4 μm. Specifically, use ultraviolet lithography to expose and remove the photoresist in the area where the metal layer needs to be plated (the area with a side length dimension of 50-150 μm), and then use the dual ion beam sputtering method to plate the first metal layer 1 in the exposed area. The first metal layer 1 is Cr / Au, and the thickness of Cr is 20-50 nm. As Figure 4 shown, a sapphire-Cr / Au layer is obtained. Ultraviolet lithography and dual ion beam sputtering methods are conventional preparation methods in the art and will not be elaborated here.

[0034] Optionally, a cross alignment reticle 3 is prepared on the substrate, and the cross alignment reticle 3 is used for alignment in the subsequent preparation process.

[0035] S330, a sacrificial layer is prepared on the side of the first metal layer away from the substrate by using a second preparation method.

[0036] On the side of the first metal layer 2 away from the substrate 1, a film layer is prepared by using a room-temperature magnetron sputtering deposition method. An ultraviolet lithography and wet etching are used to prepare a sacrificial layer on the film layer with a side length dimension of 56 - 162 μm and a thickness of 1.5 - 2.5 μm. In the embodiment of the present application, the sacrificial layer is a silicon dioxide sacrificial layer because a high-temperature environment of 300 - 450 °C is required when preparing the manganese cobalt nickel oxide material layer, and silicon dioxide has a good high-temperature resistance effect. In addition, silicon dioxide can be etched away by using a BOE etching solution (Buffered Oxide Etch, which is a mixture of 49% hydrofluoric acid aqueous solution and ammonium fluoride aqueous solution in proportion), while the manganese cobalt nickel oxide material is resistant to the BOE etching solution. It can be understood that the sacrificial layer can also be other materials as long as they can meet the requirements of high-temperature resistance and being easily etched by the BOE etching solution. In the embodiment of the present application, the thickness of the silicon dioxide sacrificial layer is 1.5 - 2.5 μm. If it is too thin, the effect of reducing heat conduction is not obvious; if it is too thick, it may affect the stability of the manganese cobalt nickel oxide microbridge structure.

[0037] Specifically, a silicon dioxide film layer is grown on the substrate by using a room-temperature magnetron sputtering deposition method. The thickness of the silicon dioxide film layer is 1.5 - 2.5 μm. With the aid of a cross alignment reticle 3, an ultraviolet lithography is used to define a photoresist window, and the size of the photoresist window is slightly larger than the size of the first metal layer 2. For example, the size of the photoresist window can be 56 - 162 μm. The silicon dioxide film layer within the photoresist window is protected, and then it is added to the BOE etching solution to etch away the silicon dioxide film layer outside the photoresist window to obtain a silicon dioxide sacrificial layer (as Figure 4 shown). After the silicon dioxide sacrificial layer is prepared, the photoresist is removed. The magnetron sputtering deposition method and the wet etching are conventional preparation methods in the art and will not be elaborated here.

[0038] S340, a first manganese cobalt nickel oxide layer is prepared on the side of the sacrificial layer away from the substrate by using a third preparation method.

[0039] On the side of the sacrificial layer away from the substrate 1, at a growth temperature of 300 - 450 °C, a first manganese cobalt nickel oxide layer 5 with a thickness of 2.8 - 3.2 μm is prepared by using a magnetron sputtering deposition method. Specifically, a mask plate is used to block the cross alignment reticle 3, and at a growth temperature of 300 - 450 °C, a first manganese cobalt nickel oxide layer 5 with a thickness of 2.8 - 3.2 μm is prepared by using a magnetron sputtering deposition method. As Figure 4As shown, the first manganese cobalt nickel oxide layer 5 includes a first portion 51 parallel to the substrate, and further includes second portions 52 located on both sides of the first portion. After the sacrificial layer is etched away, the second portions 52 are used to support the first portion 51, that is, a manganese cobalt nickel oxide microbridge is formed. The magnetron sputtering deposition method is a conventional preparation method in the art and will not be elaborated here.

[0040] Optionally, before this step, on the side of the sacrificial layer away from the substrate 1, a calcium fluoride thin film layer 4 with a thickness of 40 - 60 nm is prepared by using ultraviolet lithography and room-temperature magnetron sputtering deposition method. The calcium fluoride thin film layer 4 covers the first surface and the second surface of the sacrificial layer. Among them, the first surface is parallel to the substrate 1, that is, the calcium fluoride thin film layer 4 covers the upper surface of the sacrificial layer; the second surface is the surface in the thickness direction of the sacrificial layer, that is, the calcium fluoride thin film layer 4 covers the side surface in the thickness direction of the sacrificial layer. Specifically, with the help of the cross alignment reticle 3, an ultraviolet lithography is used to define a photoresist window, and the size of this photoresist window is the same as that of the sacrificial layer, which can be 56 - 162 μm. The calcium fluoride thin film layer 4 is prepared by using room-temperature magnetron sputtering deposition method within this photoresist window, and the thickness of the calcium fluoride thin film layer 4 is 40 - 60 nm. The magnetron sputtering deposition method is a conventional preparation method in the art and will not be elaborated here.

[0041] S350, on the side of the first manganese cobalt nickel oxide layer away from the substrate, the second metal layer is prepared by using the first preparation method.

[0042] On the side of the first manganese cobalt nickel oxide layer 5 away from the substrate 1, a second metal layer 6 is prepared by using ultraviolet lithography and dual ion beam sputtering method. The second metal layer 6 includes a plurality of first squares arranged periodically. The side length dimension of each first square is 5 - 5.4 μm, the thickness is 0.05 - 0.1 μm, and the interval between two adjacent first squares is 10 - 10.5 μm.

[0043] Specifically, with the help of the cross alignment reticle 3, a plurality of photoresist windows are defined by using ultraviolet lithography. The size of each photoresist window is 5 - 5.4 μm, and the interval between adjacent photoresist windows is 10 - 10.5 μm. The photoresist in the photoresist window is removed by exposure, and the second metal layer 6 is deposited on the exposed area by using dual ion beam sputtering method. The second metal layer 6 is Cr / Au. The side length dimension of each first square is 5 - 5.4 μm, the thickness is 0.05 - 0.1 μm, and the thickness of Cr is 20 - 50 nm. As Figure 4 shown, the second metal layer 6 forms a plurality of first squares arranged in an array on the surface of the first manganese cobalt nickel oxide layer 5. After the second metal layer 6 is prepared, the photoresist is removed. The ultraviolet lithography and dual ion beam sputtering methods are conventional preparation methods in the art and will not be elaborated here.

[0044] S360, on the side of the second metal layer away from the substrate, the second manganese cobalt nickel oxide layer is prepared by using the third preparation method.

[0045] On the side of the second metal layer 6 away from the substrate 1, at a growth temperature of 300 - 450 °C, a second manganese cobalt nickel oxide layer 7 with a thickness of 1.4 - 1.6 μm is prepared by magnetron sputtering deposition. Specifically, a mask is used to cover the cross alignment reticle 3, and at a growth temperature of 300 - 450 °C, a second manganese cobalt nickel oxide layer 7 with a thickness of 1.4 - 1.6 μm is prepared by magnetron sputtering deposition. As Figure 4 shown, the second manganese cobalt nickel oxide layer 7 covers the upper surface of the second metal layer 6. The magnetron sputtering deposition method is a conventional preparation method in the art and will not be elaborated here.

[0046] S370, a third metal layer is prepared on the side of the second manganese cobalt nickel oxide layer away from the substrate by the first preparation method.

[0047] On the side of the second manganese cobalt nickel oxide layer 7 away from the substrate 1, a third metal layer 8 is prepared by ultraviolet lithography and dual ion beam sputtering. The third metal layer 8 includes a plurality of second squares arranged periodically. The side length of each second square is 2.5 - 4 μm, and the thickness is 0.05 - 0.1 μm. The orthographic projection of the plurality of second squares on the surface of the substrate 1 coincides with the orthographic projection of the plurality of first squares.

[0048] Specifically, with the help of the cross alignment reticle 3, a plurality of photoresist windows are defined by ultraviolet lithography. The size of each photoresist window is 2.5 - 4 μm, and the orthographic projection of each photoresist window on the surface of the substrate 1 coincides with the orthographic projection of the corresponding first square. The photoresist in the photoresist window is removed by exposure, and the third metal layer 8 is deposited on the exposed area by dual ion beam sputtering. The third metal layer 8 is Ti / Au. The side length of each second square is 2.5 - 4 μm, and the thickness is 0.05 - 0.1 μm. As Figure 4 shown, the third metal layer 8 forms a plurality of second squares arranged in an array on the surface of the second manganese cobalt nickel oxide layer 7. After the third metal layer 8 is prepared, the photoresist is removed. The ultraviolet lithography and dual ion beam sputtering methods are conventional preparation methods in the art and will not be elaborated here.

[0049] S380, the sacrificial layer is released by wet etching to obtain an infrared thermal detector.

[0050] In some embodiments, before the sacrificial layer is released by wet etching, a protective layer (i.e., photoresist) is set on the surfaces of the first manganese cobalt nickel oxide layer 5 and the second manganese cobalt nickel oxide layer 7 by ultraviolet lithography. As Figure 4As shown, in order to obtain an infrared thermal detector that meets the structural requirements, part of the material of the first manganese cobalt nickel oxide layer 5 needs to be etched away. Exemplarily, a mixed etching solution of hydrochloric acid and water with a ratio of 1:1 is used to etch part of the manganese cobalt nickel oxide material. Specifically, before etching, the parts of the first manganese cobalt nickel oxide layer 5 and the second manganese cobalt nickel oxide layer 7 that need to be retained are protected with photoresist, and then it is placed in a mixed etching solution of hydrochloric acid and water with a ratio of 1:1 to etch part of the manganese cobalt nickel oxide material. Then, an external electrode 9 is plated on the outer surface of the second part 51 of the first manganese cobalt nickel oxide layer 5, and the external electrode 9 is connected to the electrode lead 10. Finally, the device is placed in a BOE etching solution for wet etching to release the silicon dioxide sacrificial layer. After etching away the silicon dioxide sacrificial layer, the photoresist on the device is removed to obtain a manganese cobalt nickel oxide microbridge structure.

[0051] Optionally, the external electrode 9 can be prepared simultaneously with the third metal layer 8 in step S370.

[0052] Optionally, the preparation method further includes cutting the device with a manganese cobalt nickel oxide microbridge structure from the substrate, bonding it to the copper sheet of an anti-static shielding package, and connecting the electrode lead 10 to an external electronic device (for example, a readout circuit or an A / D converter) by ultrasonic spot welding.

[0053] The embodiment of the present application provides a method for preparing an infrared thermal detector. This method forms a manganese cobalt nickel oxide microbridge structure by preparing a sacrificial layer and then etching away the sacrificial layer, so that the device has a lower thermal conductivity. In addition, an infrared thermal detector with a metal layer - air layer (or vacuum layer) - manganese cobalt nickel oxide layer - metal layer array - manganese cobalt nickel oxide layer - metal layer array is formed by this preparation method, which improves its infrared absorption in the range of 8 - 12 μm.

[0054] To explain the present application more clearly, the following is illustrated by specific embodiments. Embodiment 1

[0055] This embodiment provides a method for preparing an infrared thermal detector, which specifically includes the following steps: Step 1, prepare a Cr / Au metal reflection layer (i.e., the first metal layer) on a sapphire substrate. A Cr / Au metal reflection layer with a side length of 50 μm and a thickness of 150 nm is prepared above the sapphire substrate by ultraviolet lithography and dual ion beam sputtering method, where the thickness of the Cr layer is 30 nm and the thickness of the Au layer is 120 nm; Step 2, prepare a silicon dioxide sacrificial layer. Prepare a silicon dioxide film layer by magnetron sputtering deposition. For example, use a Si target for sputtering, the reaction gas is a mixed gas of oxygen and argon with a flow rate of 20 sccm, the oxygen-argon ratio is 20:80, and the sputtering rate is 3.5 nm / min. Use ultraviolet lithography and wet etching to prepare a silicon dioxide sacrificial layer with a side length slightly larger than the bottom metal reflective layer above the Cr / Au reflective layer. The mesa size of the silicon dioxide sacrificial layer is 56 μm and the thickness is 1.5 μm. After the silicon dioxide sacrificial layer is prepared, remove the photoresist; Step 3, prepare a calcium fluoride thin film. Make a photoresist window with a side length of 56 μm by ultraviolet lithography. Then, use magnetron sputtering deposition to make a calcium fluoride thin film covering the first surface and the second surface of the SiO2 sacrificial layer. The thickness of the calcium fluoride thin film is 50 nm. Among them, the first surface is parallel to the substrate, and the second surface is the surface in the thickness direction of the sacrificial layer. After the calcium fluoride thin film is prepared, remove the photoresist; Step 4, prepare the first manganese cobalt nickel oxide layer. Use a mask to cover the cross alignment crosshairs, and magnetron sputter deposit a manganese cobalt nickel oxide layer with a thickness of 3.0 μm at a growth temperature of 300 - 450 °C to prepare the first manganese cobalt nickel oxide layer; Step 5, prepare an intermediate layer of Cr / Au periodic metal structure squares (i.e., the second metal layer). By ultraviolet lithography, prepare multiple photoresist windows on the upper surface of the first manganese cobalt nickel oxide layer. The side length of each photoresist window is 5.2 μm, and the interval between adjacent two photoresist windows is 10 μm. Subsequently, use dual ion beam sputtering to prepare an intermediate layer of Cr / Au periodic metal structure with a thickness of 0.10 μm. After the second metal layer is prepared, remove the photoresist; Step 6, prepare the second manganese cobalt nickel oxide layer. Use a mask to cover the cross alignment crosshairs, and magnetron sputter deposit manganese cobalt nickel oxide with a thickness of 1.5 μm at a growth temperature of 300 - 450 °C to prepare the second manganese cobalt nickel oxide layer; Step 7, prepare a top layer of Ti / Au periodic metal structure squares (i.e., the third metal layer). By ultraviolet lithography, prepare multiple photoresist windows on the upper surface of the second manganese cobalt nickel oxide layer. The side length of each photoresist window is 2.5 μm, and the orthographic projection of each photoresist window on the surface of the substrate coincides with the orthographic projection of the corresponding structure square of the second metal layer. Subsequently, use dual ion beam sputtering to prepare a top layer of Ti / Au periodic metal structure with a thickness of 0.10 μm and an external metal electrode. After the preparation is completed, remove the photoresist; Step 8: Release the silica sacrificial layer to obtain a self-supporting manganese cobalt nickel oxide microbridge. First, apply photoresist on the surfaces of part of the first manganese cobalt nickel oxide layer and the second manganese cobalt nickel oxide layer through ultraviolet lithography. Use a mixed etching solution of hydrochloric acid and water with a ratio of 1:1 to etch the unnecessary manganese cobalt nickel oxide materials. Wet-etch the silica sacrificial layer with BOE etching solution. After removing the photoresist, an infrared thermal detector with a self-supporting manganese cobalt nickel oxide microbridge is obtained; Step 9: Complete the encapsulation spot welding of the infrared thermal detector. Divide and slice the substrate wafer, paste and encapsulate it onto the copper sheet of an anti-static shielding package. Connect the external electrodes to external electronic devices through electrode leads by ultrasonic spot welding.

[0056] When this infrared thermal detector is used for testing, the average absorption rate of this device in the range of 8 - 12 μm is 35% - 90%. Example 2

[0057] This example provides a method for fabricating an infrared thermal detector, which specifically includes the following steps: Step 1: Prepare a Cr / Au metal reflection layer (i.e., the first metal layer) on a sapphire substrate. Prepare a Cr / Au metal reflection layer with a side length of 100 μm and a thickness of 150 nm above the sapphire substrate through ultraviolet lithography and dual ion beam sputtering method, where the thickness of the Cr layer is 30 nm and the thickness of the Au layer is 120 nm; Step 2: Prepare the silica sacrificial layer. Prepare a silica film layer through magnetron sputtering deposition. For example, use an Si target for sputtering, the reaction gas is a mixed gas of oxygen and argon with a flow rate of 20 sccm, the oxygen-argon ratio is 20:80, and the sputtering rate is 3.5 nm / min. Use ultraviolet lithography and wet etching to prepare a silica sacrificial layer with a side length slightly larger than the bottom metal reflection layer above the Cr / Au reflection layer. The mesa size of the silica sacrificial layer is 110 μm and the thickness is 1.5 μm. After preparing the silica sacrificial layer, remove the photoresist; Step 3: Prepare a calcium fluoride thin film. Make a photoresist window with a side length of 110 μm through ultraviolet lithography method. Then, use magnetron sputtering deposition method to make a calcium fluoride thin film covering the first surface and the second surface of the SiO2 sacrificial layer. The thickness of the calcium fluoride thin film is 50 nm. Among them, the first surface is parallel to the substrate, and the second surface is the surface in the thickness direction of the sacrificial layer. After preparing the calcium fluoride thin film, remove the photoresist; Step 4: Prepare the first manganese cobalt nickel oxide layer. Use a mask to cover the cross alignment reticle, and magnetron sputter deposit a manganese cobalt nickel oxide layer with a thickness of 3.0 μm at a growth temperature of 300 - 450 °C to obtain the first manganese cobalt nickel oxide layer; Step 5, prepare an intermediate Cr / Au periodic metal structure square (i.e., the second metal layer). By means of ultraviolet lithography, a plurality of photoresist windows are prepared on the upper surface of the first manganese cobalt nickel oxide layer. The side length of each photoresist window is 5.2 μm, and the interval between two adjacent photoresist windows is 10 μm. Subsequently, an intermediate Cr / Au periodic metal structure with a thickness of 0.10 μm is prepared by dual ion beam sputtering. After the second metal layer is prepared, the photoresist is removed; Step 6, prepare the second manganese cobalt nickel oxide layer. Use a mask to block the cross alignment crosshairs, and magnetron sputter deposit manganese cobalt nickel oxide with a thickness of 1.5 μm at a growth temperature of 300 - 450 °C to prepare the second manganese cobalt nickel oxide layer; Step 7, prepare a top Ti / Au periodic metal structure square (i.e., the third metal layer). By means of ultraviolet lithography, a plurality of photoresist windows are prepared on the upper surface of the second manganese cobalt nickel oxide layer. The side length of each photoresist window is 3.5 μm, and the positive projection of each photoresist window on the surface of the substrate coincides with the positive projection of the corresponding structure square of the second metal layer. Subsequently, a top Ti / Au periodic metal structure with a thickness of 0.10 μm and an external metal electrode are prepared by dual ion beam sputtering. After the preparation is completed, the photoresist is removed; Step 8, release the silicon dioxide sacrificial layer to obtain a manganese cobalt nickel oxide self-supporting microbridge. First, photoresist is set on the surfaces of part of the first manganese cobalt nickel oxide layer and the second manganese cobalt nickel oxide layer by ultraviolet lithography. The unnecessary manganese cobalt nickel oxide material is etched with a mixed etching solution of hydrochloric acid and water with a ratio of 1:1. Wet etching is carried out with a BOE etching solution to release the silicon dioxide sacrificial layer. After removing the photoresist, an infrared thermal detector with a manganese cobalt nickel oxide self-supporting microbridge is obtained; Step 9, complete the encapsulation spot welding of the infrared thermal detector. The substrate wafer is segmented and sliced, and pasted and encapsulated onto the copper sheet of an anti-static shielded package. The external electrode is connected to an external electronic device through an electrode lead by ultrasonic spot welding.

[0058] When this infrared thermal detector is used for testing, the average absorption rate of this device in the range of 8 - 12 μm is 40 - 95%. Example 3

[0059] This example provides a method for preparing an infrared thermal detector, which specifically includes the following steps: Step 1, prepare a Cr / Au metal reflection layer (i.e., the first metal layer) on a sapphire substrate. By means of ultraviolet lithography and dual ion beam sputtering, a Cr / Au metal reflection layer with a side length of 150 μm and a thickness of 150 nm is prepared above the sapphire substrate, wherein the thickness of the Cr layer is 30 nm and the thickness of the Au layer is 120 nm; Step 2, prepare the silicon dioxide sacrificial layer. Prepare the silicon dioxide film layer by magnetron sputtering deposition method. For example, use a Si target for sputtering, the reaction gas is a mixed gas of oxygen and argon, the flow rate is 20 sccm, the oxygen-argon ratio is 20:80, and the sputtering rate is 3.5 nm / min. Use ultraviolet lithography and wet etching to prepare a silicon dioxide sacrificial layer with a side length slightly larger than the bottom metal reflective layer above the Cr / Au reflective layer. The mesa size of the silicon dioxide sacrificial layer is 162 μm and the thickness is 1.5 μm. After the silicon dioxide sacrificial layer is prepared, remove the photoresist; Step 3, prepare the calcium fluoride film. Use ultraviolet lithography method to make a photoresist window with a side length of 162 μm. Then, use magnetron sputtering deposition method to make a calcium fluoride film covering the first surface and the second surface of the SiO2 sacrificial layer. The thickness of the calcium fluoride film is 50 nm. Among them, the first surface is parallel to the substrate, and the second surface is the surface in the thickness direction of the sacrificial layer. After the calcium fluoride film is prepared, remove the photoresist; Step 4, prepare the first manganese cobalt nickel oxide layer. Use a mask to block the cross alignment crosshairs, and magnetron sputter deposit a manganese cobalt nickel oxide layer with a thickness of 3.0 μm at a growth temperature of 300 - 450 °C to obtain the first manganese cobalt nickel oxide layer; Step 5, prepare the intermediate layer Cr / Au periodic metal structure square (i.e., the second metal layer). By ultraviolet lithography method, prepare multiple photoresist windows on the upper surface of the first manganese cobalt nickel oxide layer. The side length of each photoresist window is 5.2 μm, and the interval between adjacent two photoresist windows is 10 μm. Then, use dual ion beam sputtering method to prepare an intermediate layer Cr / Au periodic metal structure with a thickness of 0.10 μm. After the second metal layer is prepared, remove the photoresist; Step 6, prepare the second manganese cobalt nickel oxide layer. Use a mask to block the cross alignment crosshairs, and magnetron sputter deposit manganese cobalt nickel oxide with a thickness of 1.5 μm at a growth temperature of 300 - 450 °C to obtain the second manganese cobalt nickel oxide layer; Step 7, prepare the top layer Ti / Au periodic metal structure square (i.e., the third metal layer). By ultraviolet lithography method, prepare multiple photoresist windows on the upper surface of the second manganese cobalt nickel oxide layer. The side length of each photoresist window is 4 μm, and the orthographic projection of each photoresist window on the surface of the substrate coincides with the orthographic projection of the corresponding structure square of the second metal layer. Then, use dual ion beam sputtering method to prepare a top layer Ti / Au periodic metal structure with a thickness of 0.10 μm and an external metal electrode. After the preparation is completed, remove the photoresist; Step 8: Release the silicon dioxide sacrificial layer to obtain a self-supporting manganese cobalt nickel oxide microbridge. First, apply photoresist on the surfaces of part of the first manganese cobalt nickel oxide layer and the second manganese cobalt nickel oxide layer through ultraviolet lithography. Use an etching solution of a 1:1 mixture of hydrochloric acid and water to etch the unnecessary manganese cobalt nickel oxide material. Wet-etch the silicon dioxide sacrificial layer with BOE etching solution, and after removing the photoresist, obtain an infrared thermal detector with a self-supporting manganese cobalt nickel oxide microbridge; Step 9: Complete the encapsulation spot welding of the infrared thermal detector. Divide and slice the substrate wafer, paste and encapsulate it onto the copper sheet of an anti-static shielding case, and connect the external electrodes to external electronic devices through electrode leads by ultrasonic spot welding.

[0060] Using this infrared thermal detector for testing, the average absorption rate of this device in the range of 8 - 12 μm is 45 - 95%. Comparative Example 1

[0061] This embodiment provides a method for preparing an infrared thermal detector without a microbridge structure, which specifically includes the following steps: Step 1: Prepare a cross-aligned reticle on a sapphire substrate. Prepare a Cr / Au metal cross-aligned reticle above the sapphire substrate through ultraviolet lithography and dual ion beam sputtering methods; Step 2: Prepare a manganese cobalt nickel oxide layer. Use a mask to cover the cross-aligned reticle, and magnetron sputter deposit a manganese cobalt nickel oxide layer with a thickness of 4.5 μm at a growth temperature of 300 - 450 °C to obtain a manganese cobalt nickel oxide layer; Step 3: Prepare a manganese cobalt nickel oxide sensitive element. Perform sensitive element overlay through ultraviolet lithography, prepare a photoresist protection layer with a side length of 56 μm on the upper surface of the manganese cobalt nickel oxide layer, and use an etching solution of a 1:1 mixture of hydrochloric acid and water to wet-etch the sensitive element, removing the unnecessary manganese cobalt nickel oxide material to obtain a sensitive element mesa; Step 4: Prepare a top Ti / Au metal layer. Through ultraviolet lithography, prepare photoresist windows matching the external electrodes on both sides of the upper surface of the manganese cobalt nickel oxide sensitive element, and then prepare a 0.10 μm thick top Ti / Au metal layer and external metal electrodes by dual ion beam sputtering method. After preparation, strip off the photoresist and the unnecessary Ti / Au film layer; Step 5: Complete the encapsulation spot welding of the infrared thermal detector. Divide and slice the substrate wafer, paste and encapsulate it onto the copper sheet of an anti-static shielding case, and connect the external electrodes to external electronic devices through electrode leads by ultrasonic spot welding.

[0062] Using this infrared thermal detector for testing, the average absorption rate of this device in the range of 8 - 12 μm is 16 - 20%.

[0063] By comparing Example 1 and Comparative Example 1, it can be seen that the infrared thermal detector prepared in the embodiment of the present application has good infrared absorption in the range of 8-12 μm due to the formation of a strong magnetic resonance absorption structure of metal layer-air layer (or vacuum layer)-manganese cobalt nickel oxide layer-metal layer array-manganese cobalt nickel oxide layer-metal layer array, and the average absorption rate is as high as 35-90%; while the infrared thermal detector in Comparative Example 1 lacks an air cavity, a microbridge structure and a metal layer array structure, and the average absorption rate in the range of 8-12 μm is only 16-20%. In addition, the thermal conductivity of the infrared thermal detector in Example 1 is about 10 -6 W / K, and the thermal conductivity of the infrared thermal detector in Comparative Example 1 is about 10 -3 W / K, and the difference between the two is about three orders of magnitude, that is, the infrared thermal detector in Example 1 has higher sensitivity.

[0064] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, advantages, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, advantages, effects, etc. are essential for each embodiment of the present application. In addition, the above-disclosed specific details are only for the purpose of illustration and easy understanding, rather than limitations. The above details do not limit the present application to necessarily adopt the above specific details to implement.

[0065] The block diagrams of the devices, apparatuses, equipment, and systems involved in the present application are only illustrative examples and do not intend to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open-ended words, meaning "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used herein refer to the word "and / or" and can be used interchangeably with it, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to" and can be used interchangeably with it.

[0066] It should also be noted that in the devices, equipment, and methods of the present application, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent solutions of the present application.

[0067] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be very apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

[0068] The foregoing description has been presented for purposes of illustration and description. In addition, the description is not intended to limit embodiments of the present application to the forms disclosed herein. Although several example aspects and embodiments have been discussed above, those skilled in the art will recognize some variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. An infrared thermal detector, characterized in that, Comprising: A substrate; A first metal layer, stacked on one surface of the substrate; A first manganese cobalt nickel oxide layer, disposed on a side of the first metal layer away from the substrate; A second metal layer, stacked on a surface of the first manganese cobalt nickel oxide layer away from the substrate; A second manganese cobalt nickel oxide layer, stacked on a surface of the second metal layer away from the substrate; A third metal layer, stacked on a surface of the second manganese cobalt nickel oxide layer away from the substrate; wherein, An air layer or a vacuum layer is provided between the first metal layer and the first manganese cobalt nickel oxide layer.

2. The infrared thermal detector according to claim 1, characterized in that, The first manganese cobalt nickel oxide layer includes: A first part, parallel to the substrate; A second part, located on both sides of the first part, for supporting the first part.

3. The infrared thermal detector according to claim 1 or 2, characterized in that, Calcium fluoride is coated on a surface of the first manganese cobalt nickel oxide layer close to the first metal layer.

4. The infrared thermal detector according to claim 1 or 2, wherein The second metal layer includes a plurality of first squares arranged in an array, each first square having a side length dimension of 5 - 5.4 μm and a thickness of 0.05 - 0.1 μm, and the interval between two adjacent first squares is 10 - 10.5 μm; The third metal layer includes a plurality of second squares arranged in an array, each second square having a side length dimension of 2.5 - 4.5 μm and a thickness of 0.05 - 0.1 μm; wherein, The orthographic projection of the plurality of second squares on the surface of the substrate coincides with the orthographic projection of the plurality of first squares.

5. A method for preparing an infrared thermal detector as described in any one of claims 1-4, characterized in that, Comprising: Providing a substrate; Preparing a first metal layer on one side of the substrate by a first preparation method; Preparing a sacrificial layer on a side of the first metal layer away from the substrate by a second preparation method; Preparing a first manganese cobalt nickel oxide layer on a side of the sacrificial layer away from the substrate by a third preparation method; Preparing a second metal layer on a side of the first manganese cobalt nickel oxide layer away from the substrate by the first preparation method; Preparing a second manganese cobalt nickel oxide layer on a side of the second metal layer away from the substrate by the third preparation method; Preparing a third metal layer on a side of the second manganese cobalt nickel oxide layer away from the substrate by the first preparation method; Using wet etching to release the sacrificial layer to obtain the infrared thermal detector.

6. The method according to claim 5, wherein Comprising: Before preparing the first manganese cobalt nickel oxide layer on a side of the sacrificial layer away from the substrate, preparing a calcium fluoride thin film layer on a side of the sacrificial layer away from the substrate by a fourth preparation method, and the calcium fluoride thin film layer covers a first surface and a second surface of the sacrificial layer.

7. The method according to claim 6, wherein The fourth preparation method includes ultraviolet lithography and room temperature magnetron sputtering deposition method; The thickness of the calcium fluoride thin film layer is 40 - 60 nm.

8. The method according to claim 5 or 6, wherein The first preparation method includes ultraviolet lithography and dual ion beam sputtering method; The second preparation method includes room temperature magnetron sputtering deposition method, ultraviolet lithography and wet etching; The third preparation method includes high temperature magnetron sputtering deposition method, and the high temperature is 300 - 450 °C.

9. The method according to claim 5 or 6, characterized in that the side length dimension of the first metal layer is 50 - 150 μm, and the thickness is 0.15 - 0.4 μm; the side length dimension of the sacrificial layer is 56 - 162 μm, and the thickness is 1.5 - 2.5 μm; the thickness of the first manganese cobalt nickel oxide layer is 2.8 - 3.2 μm; the thickness of the second manganese cobalt nickel oxide layer is 1.4 - 1.6 μm.

10. The method according to claim 5 or 6, characterized in that, Comprising: before using wet etching to release the sacrificial layer to obtain the infrared thermal detector, a protective layer is provided on the surfaces of the first manganese cobalt nickel oxide layer and the second manganese cobalt nickel oxide layer by using ultraviolet lithography.

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