A wideband infrared detector and a preparation method thereof

Abstract

The application discloses a wide-band infrared detector and a preparation method thereof. The application sequentially constructs a medium micro-bridge, a lanthanum nickelate conductive oxide bottom electrode, a manganese-cobalt-nickel-oxygen pyramid structure surface detection element, a manganese-cobalt-nickel-oxygen compensation element, a NiCr top electrode and a compensation element top electrode on a silicon substrate, and realizes wide-band infrared detection. The device design greatly reduces infrared reflection loss of the sensitive element and an air interface; in combination with a nickel-chromium absorption layer top electrode and a lanthanum nickelate absorption layer bottom electrode, the device photosensitive element realizes near-perfect absorption (more than 90%) to a wide band of 0.3-30 microns. The application effectively improves the wide-band light absorption efficiency of the manganese-cobalt-nickel-oxygen device, and can be applied to an array detector device.

Description

Technical Field

[0001] This invention relates to a wideband infrared detector and its fabrication method. More specifically, it relates to a wideband infrared detector with a pyramidal micro-roughened structure based on a manganese-cobalt-nickel-oxygen thermistor and its fabrication method. Background Technology

[0002] Manganese cobalt nickel oxide (MCNO) material is an important thermistor material with a broad absorption spectrum and a high negative temperature coefficient of resistance, making it well-suited for fabricating uncooled infrared detectors. [1]-[3] Furthermore, its performance is relatively stable, its manufacturing cost is low, and its resistivity is adjustable, making it widely used in both military and civilian infrared detection fields. However, this material also has its shortcomings: the manganese-cobalt-nickel oxide thin film has weak absorption in the 3-14μm mid-infrared window band, resulting in poor photothermal conversion efficiency. [4] While manganese cobalt nickel-oxygen (MCO) exhibits strong infrared absorption in the 15-30 μm band due to phonon absorption peaks, its high refractive index and extinction coefficient result in significant interfacial reflection losses. Considering only the thermistor layer of MCO devices, its absorption in most of the 0.3–30 μm band is approximately 10–50%, which greatly limits its application feasibility. [5] .

[0003] This patent designs a wide-band infrared detector with top and bottom electrodes of a pyramid-shaped micro-rough structure and applies it to infrared detectors. This will effectively solve the problem of limited absorption and photothermal conversion efficiency of the device and realize wide-band infrared thermal detection.

[0004] The references mentioned above are as follows:

[0005] [1]He Lin, Ling Zhi-Yuan. Studies of temperature dependent ac impedance of a negative temperature coefficient Mn-Co-Ni-O thin film thermistor[J]. Applied Physics Letters, 2011, 98(24): 242112.

[0006] [2]Huang, ZM, et al., High performance of Mn-Co-Ni-O spinel nanofilms sputtered from acetate precursors. Scientific Reports, 2015.5: p.10899.

[0007] [3] Zhang Leibo, Hou Yun, Zhou Wei, Huang Zhiming, Chu Junhao. Development of a manganese cobalt nickel oxide thin-film thermistor-type multi-element infrared detector [J]. Journal of Infrared and Millimeter Waves, 2014, 33(4):359-363.

[0008] [4]Dannenberg,R.,et al.,Infrared optical properties ofMn 1.56 Co 0.96 Ni 0.48 O4 spinel films sputter deposited in an oxygen partial pressureseries. Journal of Applied Physics, 1999.86(5):p.2590-2601.

[0009] [5] Zhang Zhibo, Wang Ding, Qiu Qinqian, Gao Yanqing, Zhou Wei, Wu Jing, Huang Zhiming. Ultraviolet-far-infrared broadband NiMn2O4 and Mn 1.56 Co 0.96 Ni 0.48 Study on optical properties of O4 [J]. Journal of Infrared and Millimeter Waves, 2020, 39(1):65-71. Summary of the Invention

[0010] The purpose of this invention is to propose a wide-band infrared detector with top and bottom electrodes of a pyramid-shaped micro-roughened structure and its fabrication method. This solves the problem of low light absorption efficiency in the important working wavelength range of 0.3-30 μm for manganese-cobalt-nickel-oxygen detectors, which prevents efficient wide-band thermal detection.

[0011] The structure of the pyramid surface micro-roughness broadband infrared detector of the present invention is described as follows: Figure 1 and Figure 2 These are schematic diagrams of the detector structure of the present invention. Figure 3 This is a flowchart of the preparation method of the present invention.

[0012] like Figure 1 , Figure 2As shown, the infrared detector structure includes: a silicon substrate, a hollow microcavity, a dielectric microbridge, a lanthanum nickel oxide conductive oxide bottom electrode, a signal electrode, a manganese cobalt nickel oxide pyramid structure surface detector element, a manganese cobalt nickel oxide compensation element, a NiCr top electrode, a power supply gold electrode, and electrical leads. The device structure can be specifically described as follows: a hollow microcavity (2) is fabricated on the silicon substrate (1), and a silicon nitride-silicon oxide-silicon nitride dielectric microbridge (3), a lanthanum nickel oxide conductive oxide bottom electrode (4) and a signal electrode (5), a manganese cobalt nickel oxide pyramid structure surface detector element (6), a manganese cobalt nickel oxide compensation element (7), a detector element NiCr top electrode (8) and a compensation element NiCr top electrode (9), a positive power supply gold electrode (10), a negative power supply gold electrode (11), and electrical leads (12).

[0013] The broadband infrared detector of this invention is fabricated as follows:

[0014] (1) Preparation of a porous silicon sacrificial layer: A low-doped, single-sided polished P-type (110) low-resistivity silicon substrate 1 with a resistivity of 0.1–1 Ω·cm was selected. A NiCr alloy thin film was sputtered at the bottom as the electrode layer, and then sealed and protected with paraffin wax. The mask material was a Si3N4 thin film deposited by PECVD with a mask thickness of 0.3 μm. The substrate was placed in a mixed solution of HF and ethanol with a ratio of HF:CH3CH2OH = 1:1. The initial anodic oxidation current density was 10 mA / cm. 2 After 2 minutes, the increase was only 50 mA / cm. 2 An oxidation time of 5 min was used to prepare a porous silicon sacrificial layer with a diameter of 100–200 μm. After preparation, the passivation layer Si3N4 film was removed in concentrated HF acid.

[0015] (2) The dielectric layer was prepared by plasma-enhanced chemical vapor deposition: 0.5 μm thick Si3N4, SiO2 and Si3N4 films were prepared sequentially on the silicon substrate and the porous silicon surface by PECVD, so as to obtain a composite structure silicon nitride / silicon oxide / silicon nitride dielectric microbridge layer 3.

[0016] (3) Preparation of lanthanum nickelate thin films using the sol-gel method: First, lanthanum nitrate hexahydrate and nickel acetate tetrahydrate were weighed at a molar ratio of 1:1. Ethanol was added at a concentration of 0.3M, and the mixture was stirred at room temperature until all lanthanum nitrate and nickel acetate were dissolved, resulting in a green and transparent solution. Then, the prepared solution was dropped onto a high-speed rotating silicon wafer at a speed of 4000 r / min for 30 s to obtain the raw material film. The raw material film was then placed in an annealing furnace for heat treatment. The annealing steps were as follows: holding at 220℃ for 2 minutes, thermally decomposing at 300℃ for 2 minutes, and finally annealing at 450℃ for 5 minutes. The above steps were repeated 60 times to obtain a lanthanum nickelate thin film material with a thickness of 1 μm.

[0017] (4) Fabrication of a patterned lanthanum nickelate common bottom electrode. A patterned lanthanum nickelate conductive oxide bottom electrode 4 was fabricated on the surface of the dielectric microbridge layer 3 using ultraviolet lithography and dry etching. This electrode layer can also serve as the bottom light-absorbing film layer of the device.

[0018] (5) Sputter deposition of manganese cobalt nickel oxide thermistor film: A manganese cobalt nickel oxide thermistor film was prepared using a LAB LineSPUTTER 5 RF magnetron sputtering system manufactured by Kurt J. Lesker, USA. Before sputtering, the substrate was ultrasonically cleaned for 5 minutes in sequence with acetone, anhydrous ethanol, and deionized water. After cleaning, the substrate was rapidly annealed in a rapid annealing furnace (350℃, 5min). The thin film was prepared by oxygen permeation using a manganese cobalt nickel oxide polycrystalline target. The preparation process parameters were: substrate temperature 200~450℃, sputtering power 50W, and base vacuum 9×10⁻⁶. -8 The sputtering pressure was 3 mTorr, the sputtering gas was Ar:O2 = 50:1, and the sputtering time was 160 h. The prepared manganese cobalt nickel oxide thin film was placed in an annealing furnace and annealed in air at 450 °C for 20 min before being removed.

[0019] (6) Fabrication of the MHC Nickel-Oxide Pyramid Micro-roughened Structure: An AZ 4330 photoresist block with a size of 3–5 μm, a period of 5–7 μm, and a thickness of 2.5 μm was fabricated using ultraviolet photolithography above a porous silicon region. After high-temperature baking, the MHC Nickel-Oxide thermistor film was etched for 20–30 s using a 1:1 diluted hydrochloric acid solution in a 35°C constant-temperature water bath. By precisely controlling the concentration, temperature, and duration of the wet etching solution, the pyramid micro-roughened structure layer was fabricated. The surface of the compensation element was not protected with photoresist, and its thickness was simultaneously reduced by the wet etching process.

[0020] (7) Dry etching was used to fabricate the micro-step structure of the probe element 6 on the surface of the manganese cobalt nickel oxide pyramid structure. Steps 1-2 μm deep were etched on the surface of the manganese cobalt nickel oxide probe element using inductively coupled plasma etching (ICP) to further reduce the reflection of incident light on the probe element surface. Cl2 was used as the reactive etching gas for ICP etching, and the thickness of the compensation element was simultaneously reduced by dry etching.

[0021] (8) NiCr absorption top electrodes for the detector and compensation elements are deposited separately. A 15-20 nm thick NiCr metal film is deposited on the detector element by dual ion beam sputtering to obtain the detector top electrode layer 8. After cleaning with resist remover, acetone, and alcohol to remove photoresist blocks and unnecessary NiCr metal layers, the compensation element NiCr top electrode layer (9) is prepared by photolithography and sputtering again. This layer also absorbs part of the infrared light. The cleaning process is repeated after the preparation of the NiCr top electrode layer 9 is completed.

[0022] (9) Fabrication of the detector element and compensation element of the device. The detector element and compensation element are protected by ultraviolet lithography and subjected to appropriate photoresist baking to achieve a side etching ratio of 1:1 in subsequent wet etching. The detector element 6 and manganese cobalt nickel oxide compensation element with appropriate size pyramid surface micro-roughness structure are prepared by hydrochloric acid wet etching for 20 to 30 seconds in a constant temperature water bath at 35℃.

[0023] (10) Cr / Au external electrode layer. The positive and negative power supply electrodes and signal terminals of the main complement structure manganese cobalt nickel oxide microbridge device are exposed by ultraviolet lithography. Positive and negative power supply gold electrodes 10-1 and 10-2 based on Cr / Au thin film and a common signal electrode layer 5 are deposited by dual ion beam sputtering. The thickness of the prepared Cr / Au film is set to Cr: 30nm and Au: 100nm, respectively.

[0024] (11) Etching the sacrificial layer to obtain the microbridge structure cavity. The porous silicon sacrificial layer was etched using a 1% (wt) KOH solution with a small amount of ethanol added for 3 min. After etching, the sample was rinsed several times with deionized water, and then immersed in a solution of ethanol and isopropanol with low surface tension to replace the deionized water remaining in the microbridge structure, so as to avoid excessive surface tension that would cause the microbridge structure to adhere and collapse.

[0025] (12) Encapsulation and spot welding to realize a wide-band infrared detector with a pyramid-shaped micro-roughened structure for top and bottom electrodes. After the device is dried, it is glued and encapsulated onto an electrical housing. The electrical signals of the device are extracted using an ultrasonic spot welder, followed by vacuum encapsulation to fabricate a wide-band infrared detector with a top and bottom electrode structure. Near-perfect absorption (over 90%) of the device's photosensitive element over a wide wavelength range of 0.3-30 μm is achieved. This invention effectively improves the wide-band light absorption efficiency of manganese cobalt nickel oxide devices and can be applied to array detector devices.

[0026] This patent has the following advantages:

[0027] 1. This invention reduces infrared reflection loss at the interface between the sensitive element and the air by designing the surface of the pyramid structure.

[0028] 2. The specially designed periodic pyramid micro-roughened structure with a bottom micro-step structure in the wideband detector of the present invention, combined with the absorption effect of the bottom lanthanum nickel oxide conductive oxide electrode, can significantly increase the absorption of manganese cobalt nickel oxide in the range of 0.3 to 30 μm to more than 90%.

[0029] 3. The invention has a simple manufacturing process and a clear structure, and has broad application prospects in uncooled infrared detection, thus possessing high utilization value. Attached image description:

[0030] Figure 1This is a side view of the pyramid-shaped micro-roughness structure top and bottom electrodes of the wideband infrared detector of the present invention.

[0031] Figure 2 This is a top view of the pyramid-shaped micro-roughness structure top and bottom electrodes of the wideband infrared detector of the present invention.

[0032] Figure 3 This is a partial schematic diagram of the pyramid micro-roughness structure of the detector of the present invention.

[0033] Figure 4 This is a flowchart illustrating the fabrication method of the wideband infrared detector for the top and bottom electrodes of the pyramid-shaped micro-roughened structure according to the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of exemplary embodiments of the present invention are described below in conjunction with the accompanying drawings.

[0035] Based on the above structure, three embodiment detectors were fabricated:

[0036] Example 1 Detector:

[0037] The device structure of a broadband infrared detector includes several parts: a low-resistivity silicon substrate, a microbridge structure, a pyramid-shaped surface detector element, a compensation element, and electrical leads. Specifically, the device structure can be described as follows: a hollow structure 2 is fabricated on the silicon substrate 1, on which a silicon nitride / silicon oxide / silicon nitride dielectric microbridge 3 is fabricated; a lanthanum nickel oxide conductive oxide bottom electrode 4 and a signal electrode layer 5 are also fabricated; a manganese cobalt nickel oxide pyramid-shaped surface detector element 6 is fabricated; a manganese cobalt nickel oxide compensation element 7 is fabricated; a NiCr top electrode for the detector element 8 and a NiCr top electrode layer for the compensation element 9 are fabricated; positive and negative power supply gold electrodes 10-1 and 10-2 are also fabricated; and leads 11 are also fabricated.

[0038] The detector should be fabricated using the following method:

[0039] (a) Preparation of a porous silicon sacrificial layer: A NiCr alloy thin film was sputtered onto a low-resistivity silicon substrate and then sealed and protected with paraffin wax. The mask material was a Si3N4 thin film deposited by PECVD. This film was then immersed in a mixed solution of HF and ethanol at a ratio of HF:CH3CH2OH = 1:1 to prepare a 100 μm square porous silicon sacrificial layer. After preparation, the passivation layer Si3N4 film was removed in concentrated HF acid. (b) Preparation of a dielectric layer using plasma-enhanced chemical vapor deposition. (c) Preparation of a lanthanum nickelate thin film using the sol-gel method: Lanthanum nitrate hexahydrate and nickel acetate tetrahydrate were weighed, and ethanol was added. The mixture was stirred at room temperature until all lanthanum nitrate and nickel acetate were completely dissolved. Then, the prepared solution was dropped onto a high-speed rotating silicon wafer to obtain a raw material film. The raw material film was then placed in an annealing furnace for heat treatment. The above steps were repeated 60 times to obtain a lanthanum nickelate thin film material with a thickness of 1 μm. (d) A patterned lanthanum nickelate conductive oxide bottom electrode 4 was fabricated on the surface of the dielectric microbridge layer 3 using ultraviolet lithography and dry etching. (e) Sputter deposition of a manganese cobalt nickel oxide thermistor film: The substrate was ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water. After cleaning, the substrate was subjected to rapid annealing (350℃, 5min); a thin film was prepared using a manganese cobalt nickel oxide polycrystalline target with oxygen permeation. The fabrication process parameters were: substrate temperature 200℃, sputtering power 50W, and base vacuum 9×10⁻⁶. -8The sputtering pressure was 3 mTorr, the sputtering gas was Ar:O2 = 50:1, and the sputtering time was 160 h. The prepared manganese cobalt nickel oxide thin film was annealed in an annealing furnace at 450 °C in air for 20 min and then removed. (f) Fabrication of the manganese cobalt nickel oxide pyramid micro-roughened structure: An AZ 4330 photoresist block with a size of 3 μm, a period of 5 μm, and a thickness of 2.5 μm was fabricated by ultraviolet photolithography above the porous silicon region. After high-temperature baking at 95 °C for 5 min, the manganese cobalt nickel oxide thermistor film was etched with pure hydrochloric acid solution for 20 s in a constant temperature water bath at 35 °C. (g) A 1 μm deep step was etched on the surface of the manganese cobalt nickel oxide material detector element using inductively coupled plasma etching (ICP). (h) The NiCr absorption layer top electrodes of the detector element and the compensation element were deposited respectively. A 15 nm thick NiCr metal film was deposited to obtain the top electrode layer 8 of the detector element. After stripping and cleaning, the compensation element was photolithographically plated again to prepare the NiCr top electrode layer 9 of the compensation element. (i) The detector sensing element and the compensation element were protected by ultraviolet lithography. The pyramid-structured surface detector element 6 and the manganese cobalt nickel oxide compensation element 7 were prepared by wet etching with an HCl water bath. (j) Cr / Au external electrode layer was deposited. The positive and negative power supply electrodes and signal terminals of the main compensation element structure manganese cobalt nickel oxide microbridge device were exposed by ultraviolet lithography. The positive and negative power supply gold electrodes 10-1 and 10-2 based on the Cr / Au thin film and the common signal electrode layer 5 were deposited by dual ion beam sputtering. (k) The porous silicon sacrificial layer was etched with a 1% (wt) KOH solution with a small amount of ethanol added for 3 min. After etching, the sample was rinsed multiple times with deionized water. Then, the sample was immersed in a solution of ethanol and isopropanol with low surface tension to replace the deionized water remaining in the microbridge structure.

[0040] Example 2 Detector:

[0041] The device structure of a broadband infrared detector includes several parts: a low-resistivity silicon substrate, a microbridge structure, a pyramid-shaped surface detector element, a compensation element, and electrical leads. Specifically, the device structure can be described as follows: a hollow structure 2 is fabricated on the silicon substrate 1, on which a silicon nitride / silicon oxide / silicon nitride dielectric microbridge 3 is fabricated; a lanthanum nickel oxide conductive oxide bottom electrode 4 and a signal electrode layer 5 are also fabricated; a manganese cobalt nickel oxide pyramid-shaped surface detector element 6 is fabricated; a manganese cobalt nickel oxide compensation element 7 is fabricated; a NiCr top electrode for the detector element 8 and a NiCr top electrode layer for the compensation element 9 are fabricated; positive and negative power supply gold electrodes 10-1 and 10-2 are also fabricated; and leads 11 are also fabricated.

[0042] The detector should be fabricated using the following method:

[0043] (a) Preparation of a porous silicon sacrificial layer: A NiCr alloy thin film was sputtered onto a low-resistivity silicon substrate and then sealed and protected with paraffin wax. The mask material was a Si3N4 thin film deposited by PECVD. This film was then immersed in a mixed solution of HF and ethanol at a ratio of HF:CH3CH2OH = 1:1 to prepare a 150 μm square porous silicon sacrificial layer. After preparation, the passivation layer Si3N4 film was removed in concentrated HF acid. (b) Preparation of a dielectric layer using plasma-enhanced chemical vapor deposition. (c) Preparation of a lanthanum nickelate thin film using the sol-gel method: Lanthanum nitrate hexahydrate and nickel acetate tetrahydrate were weighed, and ethanol was added. The mixture was stirred at room temperature until all lanthanum nitrate and nickel acetate were completely dissolved. Then, the prepared solution was dropped onto a high-speed rotating silicon wafer to obtain a raw material film. The raw material film was then placed in an annealing furnace for heat treatment. The above steps were repeated 60 times to obtain a lanthanum nickelate thin film material with a thickness of 1 μm. (d) A patterned lanthanum nickelate conductive oxide bottom electrode 4 was fabricated on the surface of the dielectric microbridge layer 3 using ultraviolet lithography and dry etching. (e) Sputter deposition of a manganese cobalt nickel oxide thermistor film: The substrate was ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water. After cleaning, the substrate was subjected to rapid annealing (350℃, 5min); a thin film was prepared using a manganese cobalt nickel oxide polycrystalline target with oxygen permeation. The fabrication process parameters were: substrate temperature 325℃, sputtering power 50W, and base vacuum 9×10⁻⁶. -8The sputtering pressure was 3 mTorr, the sputtering gas was Ar:O2 = 50:1, and the sputtering time was 160 h. The prepared manganese cobalt nickel oxide thin film was annealed in an annealing furnace at 450 °C in air for 20 min and then removed. (f) Fabrication of the manganese cobalt nickel oxide pyramid micro-rough structure: An AZ 4330 photoresist block with a size of 4 μm, a period of 6 μm, and a thickness of 2.5 μm was fabricated by ultraviolet photolithography above the porous silicon region. After high-temperature baking at 95 °C for 5 min, the manganese cobalt nickel oxide thermistor film was etched with pure hydrochloric acid solution for 25 s in a constant temperature water bath at 35 °C. (g) A step with a depth of 1.5 μm was etched on the surface of the manganese cobalt nickel oxide material detector element using inductively coupled plasma etching (ICP). (h) The NiCr absorption layer top electrodes of the detector element and the compensation element were deposited respectively. A 15 nm thick NiCr metal film was deposited to obtain the top electrode layer 8 of the detector element. After stripping and cleaning, the compensation element was photolithographically plated again to prepare the NiCr top electrode layer 9 of the compensation element. (i) The detector sensing element and the compensation element were protected by ultraviolet lithography. The pyramid-structured surface detector element 6 and the manganese cobalt nickel oxide compensation element 7 were prepared by wet etching with an HCl water bath. (j) Cr / Au external electrode layer was deposited. The positive and negative power supply electrodes and signal terminals of the main compensation element structure manganese cobalt nickel oxide microbridge device were exposed by ultraviolet lithography. The positive and negative power supply gold electrodes 10-1 and 10-2 based on the Cr / Au thin film and the common signal electrode layer 5 were deposited by dual ion beam sputtering. (k) The porous silicon sacrificial layer was etched with a 1% (wt) KOH solution with a small amount of ethanol added for 3 min. After etching, the sample was rinsed multiple times with deionized water. Then, the sample was immersed in a solution of ethanol and isopropanol with low surface tension to replace the deionized water remaining in the microbridge structure.

[0044] Example 3 Detector:

[0045] The device structure of a broadband infrared detector includes several parts: a low-resistivity silicon substrate, a microbridge structure, a pyramid-shaped surface detector element, a compensation element, and electrical leads. Specifically, the device structure can be described as follows: a hollow structure 2 is fabricated on the silicon substrate 1, on which a silicon nitride / silicon oxide / silicon nitride dielectric microbridge 3 is fabricated; a lanthanum nickel oxide conductive oxide bottom electrode 4 and a signal electrode layer 5 are also fabricated; a manganese cobalt nickel oxide pyramid-shaped surface detector element 6 is fabricated; a manganese cobalt nickel oxide compensation element 7 is fabricated; a NiCr top electrode for the detector element 8 and a NiCr top electrode layer for the compensation element 9 are fabricated; positive and negative power supply gold electrodes 10-1 and 10-2 are also fabricated; and leads 11 are also fabricated.

[0046] The detector should be fabricated using the following method:

[0047] (a) Preparation of a porous silicon sacrificial layer: A NiCr alloy thin film was sputtered onto a low-resistivity silicon substrate and then sealed and protected with paraffin wax. The mask material was a Si3N4 thin film deposited by PECVD. This film was then immersed in a mixed solution of HF and ethanol at a ratio of HF:CH3CH2OH = 1:1 to prepare a 200 μm square porous silicon sacrificial layer. After preparation, the passivation layer Si3N4 film was removed in concentrated HF acid. (b) Preparation of a dielectric layer using plasma-enhanced chemical vapor deposition. (c) Preparation of a lanthanum nickelate thin film using the sol-gel method: Lanthanum nitrate hexahydrate and nickel acetate tetrahydrate were weighed, and ethanol was added. The mixture was stirred at room temperature until all lanthanum nitrate and nickel acetate were completely dissolved. Then, the prepared solution was dropped onto a high-speed rotating silicon wafer to obtain a raw material film. The raw material film was then placed in an annealing furnace for heat treatment. The above steps were repeated 60 times to obtain a lanthanum nickelate thin film material with a thickness of 1 μm. (d) A patterned lanthanum nickelate conductive oxide bottom electrode 4 was fabricated on the surface of the dielectric microbridge layer 3 using ultraviolet lithography and dry etching. (e) Sputter deposition of a manganese cobalt nickel oxide thermistor film: The substrate was ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water. After cleaning, the substrate was rapidly annealed (350℃, 5min); a thin film was prepared using a manganese cobalt nickel oxide polycrystalline target with oxygen permeation. The fabrication process parameters were: substrate temperature 450℃, sputtering power 50W, and base vacuum 9×10⁻⁶. -8The sputtering pressure was 3 mTorr, the sputtering gas was Ar:O2 = 50:1, and the sputtering time was 160 h. The prepared manganese cobalt nickel oxide thin film was annealed in an annealing furnace at 450 °C in air for 20 min and then removed. (f) Fabrication of the manganese cobalt nickel oxide pyramid micro-rough structure: An AZ 4330 photoresist block with a size of 5 μm, a period of 7 μm, and a thickness of 2.5 μm was fabricated by ultraviolet photolithography above the porous silicon region. After high-temperature baking at 95 °C for 5 min, the manganese cobalt nickel oxide thermistor film was etched with pure hydrochloric acid solution for 30 s in a constant temperature water bath at 35 °C. (g) A 2 μm deep step was etched on the surface of the manganese cobalt nickel oxide material detector element using inductively coupled plasma etching (ICP). (h) The NiCr absorption layer top electrode of the detector element and the compensation element were deposited respectively. A 15 nm thick NiCr metal film was deposited to obtain the top electrode layer 8 of the detector element. After stripping and cleaning, the compensation element was photolithographically plated again to prepare the NiCr top electrode layer 9 of the compensation element. (i) The detector sensing element and the compensation element were protected by ultraviolet lithography. The pyramid-structured surface detector element 6 and the manganese cobalt nickel oxide compensation element 7 were prepared by wet etching with an HCl water bath. (j) Cr / Au external electrode layer was deposited. The positive and negative power supply electrodes and signal terminals of the main compensation element structure manganese cobalt nickel oxide microbridge device were exposed by ultraviolet lithography. The positive and negative power supply gold electrodes 10-1 and 10-2 based on the Cr / Au thin film and the common signal electrode layer 5 were deposited by dual ion beam sputtering. (k) The porous silicon sacrificial layer was etched with a 1% (wt) KOH solution with a small amount of ethanol added for 3 min. After etching, the sample was rinsed multiple times with deionized water. Then, the sample was immersed in a solution of ethanol and isopropanol with low surface tension to replace the deionized water remaining in the microbridge structure.

[0048] By encapsulating and spot-soldering the above-mentioned devices and leading out electrodes, a broadband manganese cobalt nickel-oxygen detector with high absorption can be obtained. Theoretical calculations show that the pyramidal micro-roughness structure of the present invention can increase the absorption of the original 10% to 50% of the manganese cobalt nickel-oxygen thermistor layer of the detector to more than 90%.

[0049] The above examples are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any modifications or changes made to the above embodiments without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A broadband infrared detector, comprising a silicon substrate (1), a hollowed-out microcavity (2), a dielectric microbridge (3), a lanthanum nickelate conductive oxide bottom electrode (4), a signal electrode (5), a manganese cobalt nickel oxide pyramidal surface detector element (6), a manganese cobalt nickel oxide compensation element (7), a NiCr top electrode (8) and a compensation element NiCr top electrode (9), a positive power supply electrode (10), and a negative power supply electrode (11); characterized in that: The structure of the broadband infrared detector device is as follows: A hollow microcavity (2) is fabricated on a silicon substrate (1); a dielectric microbridge (3) composed of silicon nitride-silicon oxide-silicon nitride material is fabricated above the hollow microcavity (2); a lanthanum nickelate conductive oxide bottom electrode (4) and a signal electrode (5) are fabricated on the dielectric microbridge (3); a manganese cobalt nickel oxide pyramid structure surface probe element (6) and a manganese cobalt nickel oxide compensation element (7) are respectively set on the lanthanum nickelate conductive oxide bottom electrode (4); a probe element NiCr top electrode (8) is set on the probe element (6), and a compensation element NiCr top electrode (9) is set on the compensation element (7); The aforementioned manganese cobalt nickel oxygen pyramid structure surface detector element (6) is a periodic pyramid micro-rough structure with a bottom micro-step structure. Combined with the absorption effect of the bottom lanthanum nickel oxide conductive oxide electrode, the absorption of manganese cobalt nickel oxygen in 0.3~30μm is greatly increased to more than 90%.

2. A method for fabricating a broadband infrared detector, characterized in that... The preparation method steps are as follows: Step 1: Fabricate rectangular porous silicon with dimensions of 100-200 μm square on a silicon substrate; Step 2: A silicon nitride-silicon dioxide-silicon nitride dielectric microbridge layer is prepared by plasma-enhanced chemical vapor deposition (PECVD). The thickness of each of the three thin films is 0.5 μm. Step 3: Prepare lanthanum nickelate oxide thin film material using the sol-gel method; Step 4: The lanthanum nickelate film is fabricated into a common bottom electrode by ultraviolet lithography and dry etching. Step 5: A 10 μm thick manganese cobalt nickel oxide film is deposited by magnetron sputtering at a temperature of 200–450 °C. Step 6: Fabricate the thermal detector element of the pyramid micro-roughness structure; fabricate a photoresist block with a size of 3-5 μm and a period of 5-7 μm on the porous silicon region using ultraviolet photolithography; after high-temperature baking, fabricate the pyramid micro-roughness structure layer by wet etching using the controllable wet side etching phenomenon of the manganese cobalt nickel oxide thermal thin film. Step 7, dry etching of micro-step structure; using inductively coupled plasma etching (ICP) method to etch a 1-2 μm deep step on the surface of manganese cobalt nickel oxide material detector element to further reduce incident light reflection; the prepared manganese cobalt nickel oxide pyramid structure surface detector element (6) is a periodic pyramid micro-rough structure with a bottom micro-step structure. Combined with the absorption effect of the bottom lanthanum nickel oxide conductive oxide bottom electrode, the absorption of manganese cobalt nickel oxide in 0.3-30 μm is greatly increased to more than 90%; Step 8: Deposit the NiCr top electrode layer for the detector and compensation elements, which also serves as the absorption layer. Step 9: Fabricate the detector and compensation elements of the device. Protect the detector and compensation elements using ultraviolet lithography and obtain the manganese cobalt nickel oxide detector and compensation elements using wet etching. Step 10: Deposit Cr / Au electrodes for the positive and negative power supply and signal terminals of the device, with a thickness of 30nm / 100nm; Step 11: Protect the device surface with photoresist and remove the cuboid porous silicon using a chemical method to obtain the detector microbridge structure; Step 12: Spot weld the detector.

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