An infrared detector based on nano-tip structure and a preparation method thereof

Abstract

This invention discloses an infrared detector based on a nano-tip structure, including a camera test box and a lens bracket, as well as an imaging objective, a nano-tip assembly, and a photosensitive array. The photosensitive array consists of multiple photosensitive elements. The nano-tip assembly includes a substrate and a nano-tip array, which includes multiple nano-tip structures. Each nano-tip structure includes a pointed structure and a metal film layer. The metal film layers of any two adjacent nano-tip structures are electrically connected through conductive lines. Each metal film layer of a row of nano-tip structures located at the edge of the nano-tip array is connected to an outgoing wire. Each photosensitive element corresponds to a sub-nano-tip array. The tip of each nano-tip structure points towards a photosensitive element. The nano-tip array and the photosensitive array generate near-field coupling. This invention features high imaging light wave collection efficiency, amplification of incident light through strong electron accumulation at the nano-tip, significantly improved photoelectric sensitivity of conventional visible light detection arrays, and the ability to achieve real-time, in-situ, high-sensitivity detection of weak radiation targets.

Description

Technical Field

[0001] This invention belongs to the field of optical imaging and detection technology, and more specifically, relates to an infrared detector based on a nano-tip structure and its fabrication method. Background Technology

[0002] Infrared detectors are devices that sense infrared radiation from a target and convert it into electrical signals. They are characterized by all-weather operation, high resolution, and strong resistance to electromagnetic interference, and are widely used in military equipment, medical diagnostics, and aerospace remote sensing. Typical infrared photosensitive imaging detectors, such as HgCdTe infrared focal plane arrays, adjust the bandgap by modifying the composition of the HgCdTe alloy. Their operating wavelength can cover a spectral range extending to 1–20 μm, with a quantum efficiency of 70%–80%, and they offer the advantage of fast photoelectric response. Photonic infrared detector arrays, such as FPAs, have reduced the minimum structural size of their photosensitive elements to the micrometer scale, achieving maximum imaging scales exceeding tens of millions of pixels and sensitivity reaching the nanowatt level. However, commonly used infrared photosensitive imaging arrays have significant drawbacks, specifically in the following aspects: (i) They exhibit large differences in photosensitive response across different infrared bands, thus requiring different infrared detector materials for different operating bands. For example, InGaAs, InSb, and HgCdTe detector materials are used for short, medium, and long-wave infrared bands, respectively; (ii) They have low photoelectric response sensitivity; (iii) When the operating temperature is too high, the inherent thermal excitation of the material rapidly increases, and the imaging quality is significantly affected by noise and dark current; (iv) They have low integration, making it difficult to simplify the system structure of infrared detectors; (v) They are costly, have low yield, and are difficult to achieve large-scale infrared photosensitive imaging. The existence of these drawbacks largely hinders the development of photosensitive imaging technology, urgently requiring new technological breakthroughs.

[0003] In recent years, nanostructures made from functional materials such as semiconductor materials like silicon and germanium, fabricated using micro-nano techniques, have attracted widespread attention due to their wide operating bandwidth, high stability, and easily tunable surface light waves. Strong accumulation of surface "roaming" electrons at the tip can be achieved through visible or infrared radiation excitation. Due to the relatively strong response and highly localized resonance enhancement, surface waves with characteristic frequencies can be effectively excited and propagated along the tip surface towards the apex. Through continuous refraction and reflection, the surface electromagnetic wave field resonantly condenses at the tip, achieving resonant super-diffraction limit enhancement of the tip's light field, with intensity jumps exceeding five orders of magnitude. However, when the contours and parameters of a micro-nano structure are determined, its optical properties and functions are generally also determined, making it difficult to meet the dynamically tunable functional requirements of micro-nano devices in complex and variable scenarios. The optical properties of nano-scale surfaces are greatly influenced by their structural parameters and the refractive index of the surrounding medium. Coupled with variable materials or structures, and by altering the dielectric constant of the variable material or the dimensional parameters of the variable structure through an external signal, the optical properties of the coupled device can be quantitatively controlled, enabling intelligently tunable infrared imaging detection. To significantly improve the photoelectric sensitivity of low-cost infrared detectors, CMOS photosensitive cameras are used for photoelectric detection, expanding the light intensity response range to handle both strong and weak light, reducing the size of photosensitive elements, increasing array scale, and improving spatial resolution, providing solutions and approaches.

[0004] Patent application number 201910082563.2 discloses a photosensitive imaging detection chip based on tip electron fluorescence excitation, including a parallel optical antenna, a fluorescent film layer, and a photosensitive array. The optical antenna is an array structure composed of multiple spaced and electrically connected antenna elements, the fluorescent film layer is an array structure composed of multiple spaced and electrically connected fluorescent film elements, and the photosensitive array is an array structure composed of multiple spaced and electrically connected photosensitive elements. The optical antenna, the fluorescent film layer, and the photosensitive array have the same shape and array size. The antenna elements of the optical antenna, the fluorescent film elements at corresponding positions in the fluorescent film layer, and the photosensitive elements at corresponding positions in the photosensitive array are aligned with each other in the vertical direction. The antenna element of the optical antenna includes at least one nano-tip that is electrically connected to each other on its top surface. The nano-tip adopts a conical structure with a curved top surface, and the tip of the nano-tip points towards the fluorescent film element. One end of the optical antenna and one end of the fluorescent film layer are respectively connected to an external control signal through metal connecting wires. The aforementioned photosensitive imaging detector chip uses nanoimprinting to fabricate its nano-tip. This process is difficult to align, has a low yield, and results in a relatively small tip sharpness, which leads to an unsatisfactory electron accumulation effect at the tip. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides an infrared detector and its preparation method, which has the characteristics of high imaging light wave collection efficiency, strong accumulation of nano-electrons to amplify incident light, significantly improving the photoelectric sensitivity of conventional visible light detection arrays, and enabling real-time in-situ high-sensitivity detection of weak radiation targets.

[0006] To achieve the above objectives, according to one aspect of the present invention, an infrared detector based on a nano-structure is provided, comprising a camera test box and a lens holder mounted on the camera test box, characterized in that:

[0007] It also includes an imaging objective, a nano-tip assembly, and a photosensitive array arranged sequentially along the optical path. The imaging objective is mounted on the lens holder, and the nano-tip assembly and the photosensitive array are respectively mounted on the camera test box. The photosensitive array is composed of multiple photosensitive elements arranged in an array.

[0008] The nano-tip assembly includes a substrate and a nano-tip array disposed on the substrate. The nano-tip array includes multiple nano-tip structures arranged in an array. Each nano-tip structure includes a pointed structure and a metal film layer covering the pointed structure. Any two adjacent nano-tip structures in each row are electrically connected through conductive lines. Any two adjacent nano-tip structures in each column are electrically connected through conductive lines. Each metal film layer of a row of nano-tip structures located at the edge of the nano-tip array is connected to an outgoing wire for connecting drive and control signals.

[0009] For each photosensitive element, there is a corresponding sub-nano-top array, the sub-nano-top array includes at least one nano-top structure, and the projection area of ​​the sub-nano-top array corresponding to the photosensitive element on the substrate does not exceed the projection area of ​​the photosensitive element on the substrate.

[0010] The tip of each of the aforementioned pointed structures points towards the photosensitive element;

[0011] The nano-tip array and the photosensitive array generate near-field coupling.

[0012] Preferably, for the nano-tip array, the lateral period is 500nm-2000nm with a duty cycle of 50%-70%, and the longitudinal period is 500nm-2000nm with a duty cycle of 50%-70%. The nano-tip structure is conical or pyramidal. The duty cycle is equal to the structure size / period size. The structure size is the bottom feature size of the nano-tip structure. If the nano-tip structure is conical, it is the bottom diameter; if the nano-tip structure is pyramidal, it is the bottom side length. The lateral period is the distance between the center lines of two nano-tip structures in the lateral direction, and the longitudinal period is the distance between the center lines of two nano-tip structures in the longitudinal direction. The lateral direction is the direction of a row, and the longitudinal direction is the direction of a column.

[0013] Preferably, the spacing between the nano-tip assembly and the photosensitive array is 40nm to 300nm to enable near-field coupling between the two.

[0014] Preferably, the tip of the nano-tip structure is dot-shaped, spherical, mushroom-shaped, or linear.

[0015] Preferably, the material of the metal film layer is selected from aluminum, chromium, copper, silver, and gold.

[0016] Preferably, each of the pointed structures is a conical structure or a regular pyramidal structure.

[0017] According to another aspect of the present invention, a method for fabricating an infrared detector based on a nano-tip structure is also provided, characterized by comprising the following steps:

[0018] 1) The process of creating a nano-assembly mainly includes the following sub-steps:

[0019] 1.1) Cleaning process I: The substrate is ultrasonically cleaned sequentially with acetone, alcohol and deionized water, and then dried. The substrate is made of silicon wafer.

[0020] 1.2) Coating process: A silicon dioxide film is deposited on one surface of a cleaned substrate using plasma-enhanced chemical vapor deposition, followed by cleaning and drying.

[0021] 1.3) Coating process: Apply photoresist to the side of the silicon dioxide film away from the substrate using a spin coater, and then dry it;

[0022] 1.4) Electron beam lithography process: The electron beam is scanned along a circular or rectangular path to expose the photoresist to light;

[0023] 1.5) Development process: The photoresist is developed and dried using a developing solution to dissolve the photoresist whose molecular weight has decreased after photosensitive denaturation, while retaining the portion of the photoresist that needs to be preserved.

[0024] 1.6) Etching process I: The magnetic neutral loop discharge plasma etching process is used to etch away the silicon dioxide film that is not covered by photoresist, so that the pattern on the silicon dioxide covered by photoresist is consistent with the pattern of the retained photoresist, thereby forming a silicon dioxide mask.

[0025] 1.7) Cleaning process II: The substrate was sequentially cleaned with NMP solution and isopropyl ketone solvent using a water bath with heating, and then dried;

[0026] 1.8) Resin Removal Process: A resist removal machine is used to remove the resist to ensure that all photoresist residue on the surface of the obtained silicon dioxide mask is removed;

[0027] 1.9) Etching process II: Inductively coupled plasma etching process is adopted, and planar ion beam is used to etch the substrate: the area on the substrate not covered by silicon dioxide mask is etched, and the etching parameters are adjusted according to the sidewall tilt angle of the required pointed structure. The area on the substrate covered by silicon dioxide mask is etched to obtain the pointed structure.

[0028] 1.10) Cleaning process III: The structure obtained in step 1.9) is ultrasonically cleaned sequentially with hydrofluoric acid, acetone, alcohol and deionized water solvent, and then dried. Hydrofluoric acid is used to remove the silicon dioxide mask.

[0029] 1.11) Magnetron sputtering process: Metal is magnetron sputtered on each pointed structure to form a metal film. During magnetron sputtering, a mask is used to ensure that no metal film is formed on the substrate between any adjacent pointed structures. Then the substrate is cleaned and dried.

[0030] 2) Integrating nano-scale components with photosensitive arrays mainly includes the following sub-steps:

[0031] 2.1) Fabrication process of electrical control leads for nano-tip array: Using a combination of 3D, photolithography and wire bonding technology, conductive wires are soldered to each metal film layer, and a conductive wire is led out from each metal film layer of a row of nano-tip structures at the edge of the nano-tip array to apply voltage to the nano-tip array;

[0032] 2.2) Optical alignment process between nano-tip assembly and photosensitive array: Align each sub-nano-tip array in the nano-tip array with a photosensitive element in the photosensitive array, and make the nano-tip assembly and the photosensitive array near-field coupled, wherein each sub-nano-tip array includes at least one nano-tip structure.

[0033] 2.3) Packaging process: A row of conductive wires of nano-tip structures at the edge of the nano-tip array are led out from the outer shell of the camera test box to connect the drive control signal. The photosensitive array is then installed into the camera test box, and the nano-tip array and the photosensitive array are made to generate near-field coupling.

[0034] Preferably, the thickness of the substrate is 100nm-300nm.

[0035] Preferably, the pointed structure is conical, with a base circle diameter of 100nm-1000nm, a cone angle of 30°-50°, and a metal film thickness of 30nm-50nm.

[0036] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0037] 1) Near-field coupling is required between the nano-tip array and the photosensitive array to allow the surface "roaming" electrons to accumulate in a controlled manner at the tip of the nano-tip and form a local strong electric field at the tip of the nano-tip structure. This electric field is an evanescent field, that is, the field strength decreases with the -2 power of the distance, thereby realizing high gain amplification of the incident light of the nano-tip structure.

[0038] 2) Due to the tip effect, a large number of surface states filled with free electrons are generated at the tip of the nano-tip structure, resulting in a high surface electron density at the tip. Simultaneously, when the excited surface wave propagates to the tip, the tip boundary guides the surface wave towards the tip, ultimately achieving nano-focusing of the incident electromagnetic radiation. For electromagnetic waves like light, the nano-tip structure can effectively perform optical wave modulation, amplifying the incident light, which is then received by the photosensitive array. Furthermore, by forming a localized focused light field on the tip surface of the nano-tip array optical antenna, a grating electric field is induced, enabling pixel-level in-situ high-sensitivity measurement and output control and dynamic adjustment of the photoinduced electrical signal, thus implementing sub-noise weak light detection.

[0039] 3) High-gain amplification of incident light by nano-tip structure: The infrared detector based on nano-tip array of the present invention has the characteristics of controlling the strong accumulation of tip electrons of nano-tip structure by visible or infrared light, and controlling the excitation and nano-convergence of surface waves on the surface of nano-tip structure to realize the intensity amplification of incident light wave.

[0040] 4) Electrically adjustable nano-tip light wave collection gain: By leveraging the electromagnetic wave convergence on the surface of the nano-tip structure and the enhanced coupling correlation of surface plasmons, the electron distribution density of the surface "roaming state" is controlled, thereby adjusting the nano-convergence intensity of the surface electromagnetic wave beam.

[0041] 5) Improved photoelectric sensitivity based on the local field enhancement effect at the tip of the nano-tip: By collecting the imaging beam with high gain through the nano-tip structure, while basically maintaining the noise level of the photosensitive structure, the photosensitive modulation mechanism is coupled based on the local field enhancement effect at the tip of the nano-tip structure, thereby improving the photoelectric sensitivity of the visible light detection array with high gain.

[0042] 6) Intelligent drive and control: The surface wave excitation and nano-convergence of the nano-structure are easily constrained, enhanced or guided by external drive and control signals such as bias electric fields, and have intelligent characteristics.

[0043] 7) Low cost: The main body of the infrared detector based on nano-tip array of the present invention is a nano-tip array and a photosensitive array encapsulated in a shell, which is easy to process and has a high yield.

[0044] 8) Improved photoelectric sensitivity: The nano-tip structure of the present invention has a metal film, which can effectively realize plasmon excitation, confine the electromagnetic field to a very small area on the surface of the metal film and cause resonance enhancement, so as to significantly improve the photoelectric sensitivity of the visible light detection array. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of an infrared detector based on a nano-scale array;

[0046] Figure 2 This is a schematic diagram of the invention for detecting visible light or infrared radiation;

[0047] Figure 3 This is a schematic diagram illustrating the electrical control of the strong accumulation of nano-electrons excited by the imaging beam and the induced grating electric field.

[0048] Figure 4 This is a schematic diagram showing the distribution of a photosensitive element corresponding to a nano-tip structure;

[0049] Figure 5 This is a schematic diagram showing a photosensitive element corresponding to the distribution of multiple nano-tip structures;

[0050] Figures 6a to 6d These are schematic diagrams showing the tips of nano-tipped structures as dot-shaped, spherical, mushroom-shaped, and linear, respectively.

[0051] Figures 7a to 7f These are schematic diagrams of the structures obtained by combining nano-tipped components in steps 1.3), 1.4), 1.6), 1.9), 1.10), and 1.11) of the molding process. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0053] Referring to the accompanying drawings, an infrared detector 6 based on a nano-tip structure includes a camera test box 4 and a lens bracket 2 mounted on the camera test box 4.

[0054] It also includes an imaging objective lens 1, a nano-aperture assembly 3, and a photosensitive array 5 arranged sequentially along the optical path. The imaging objective lens 1 is mounted on the lens holder 2. The nano-aperture assembly 3 and the photosensitive array 5 are respectively mounted on the camera test box 4. The photosensitive array 5 is composed of a plurality of photosensitive elements 51 arranged in an array. In the photosensitive array 5, there are preferably 1920 photosensitive elements 51 in one column and 1080 photosensitive elements 51 in one row (or preferably 1080 photosensitive elements 51 in one column and 1920 photosensitive elements 51 in one row).

[0055] The camera test box 4 can convert the electrical signal generated by the light received by the photosensitive array 5 into an image signal and upload it to the PC. The photosensitive element 51 is preferably a CCD photosensitive element or a CMOS photosensitive element.

[0056] The nano-tip assembly 3 includes a substrate 31 and a nano-tip array disposed on the substrate 31. The nano-tip array includes multiple nano-tip structures arranged in an array. Each nano-tip structure includes a pointed structure 32 and a metal film layer 34 surrounding the pointed structure 32. Any two adjacent metal film layers 34 of each row of nano-tip structures are electrically connected through conductive lines 33. Any two adjacent metal film layers 34 of each column of nano-tip structures are electrically connected through conductive lines 33. Each metal film layer 34 of a row of nano-tip structures located at the edge of the nano-tip array is connected to a lead wire for connecting a drive control signal 35. The drive control signal 35 can be an AC signal or a square wave signal, etc., used to change the dielectric constant of the nano-tip structure material to achieve a strong accumulation of "roaming" electrons at the tips of the nano-tip structure surface.

[0057] For each photosensitive element 51, there is a corresponding sub-nano-tip array, which includes at least one nano-tip structure. The projection area of ​​the sub-nano-tip array corresponding to the photosensitive element 51 on the substrate 31 does not exceed the projection area of ​​the photosensitive element 51 on the substrate 31. If it does exceed the projection area, it will cause different light intensities detected by different areas of the photosensitive element 51, resulting in uneven brightness of the final infrared image and affecting the imaging quality.

[0058] The tip of each of the pointed structures 32 points towards the photosensitive element 51.

[0059] The nano-tip array and the photosensitive array 5 generate near-field coupling. The nano-tip array and the photosensitive array 5 are preferably located in an inert gas, with an inert gas separating them to ensure that the distance between them allows for near-field coupling.

[0060] The nano-spin combination 3 can achieve optical amplification through nano-focusing of surface "roaming" electrons.

[0061] The imaging objective lens 1 of this invention functions as a focusing element. The photosensitive element 51 and the nano-tip structure can be configured in a one-to-one or one-to-many manner, both achieving high-gain amplification of the incident light intensity 10. The photosensitive array 5 and the camera test box 4 work together to receive optical signals and upload them to a PC. See also... Figure 2 This is a schematic diagram of the present invention for detecting visible light or infrared radiation. The light emitted by the light source 7 shines on the imaging model 9 after passing through the beam expander 8, and is detected by the infrared detector 6 of the present invention.

[0062] Furthermore, for the aforementioned nano-tip array, the lateral period is 500nm-2000nm with a duty cycle of 50%-70%, and the longitudinal period is 500nm-2000nm with a duty cycle of 50%-70%. The nano-tip structure is conical or pyramidal in shape. The duty cycle is calculated as the structure size divided by the period size. The structure size refers to the bottom characteristic dimension of the nano-tip structure; for a conical structure, it is the bottom diameter, and for a pyramidal structure, it is the bottom side length. The lateral period is the distance between the center lines of two nano-tip structures in the lateral direction, and the longitudinal period is the distance between the center lines of two nano-tip structures in the longitudinal direction. The lateral direction represents a row, and the longitudinal direction represents a column. This structural characteristic dimension falls within the subwavelength range, achieving optimal modulation of the incident light and resulting in a high electron density at the tip of the nano-tip structure, thereby forming a significant localized strong electric field.

[0063] Furthermore, the spacing between the nano-aperture assembly 3 and the photosensitive array 5 is limited to 40nm–300nm to achieve optimal near-field coupling. This spacing dimension, at the subwavelength scale, enables the interaction between surface plasmons and incident light 10, thereby amplifying the intensity of the incident light 10.

[0064] Furthermore, the tip of the nano-tip structure can be dot-shaped, spherical, mushroom-shaped, or linear. These shapes all enable the tip of the nano-tip structure to have a high surface distribution density, with the mushroom shape being the most effective, achieving the maximum electron distribution density at the tip of the nano-tip structure.

[0065] Furthermore, the material of the metal film layer 34 is selected from aluminum, chromium, copper, silver, and gold. These materials can all give the tip of the nanostructure a high surface distribution density, with gold being the most effective, achieving the largest electron distribution density at the tip of the nanostructure.

[0066] Furthermore, each of the photosensitive elements 51 has a cuboid structure, which facilitates alignment with the tip of the nano-tip structure.

[0067] Furthermore, each of the pointed structures 32 is a conical structure or a regular pyramidal structure, which has a relatively regular shape, facilitating electron transfer and concentration.

[0068] According to another aspect of the present invention, a method for fabricating an infrared detector 6 based on a nano-tip structure is also provided, comprising the following steps:

[0069] 1) The process of creating Nano-Assembly 3 mainly includes the following sub-steps:

[0070] 1.1) Cleaning process I: The substrate 31 is ultrasonically cleaned sequentially with acetone, alcohol and deionized water, and then dried; wherein, the ultrasonic cleaning with acetone, alcohol and deionized water is 5-10 minutes each; the substrate 31 is made of silicon wafer with a thickness of 100nm-300nm.

[0071] 1.2) Coating process: A silicon dioxide film 36 is deposited on one surface of a cleaned substrate 31 using plasma-enhanced chemical vapor deposition, followed by cleaning and drying.

[0072] 1.3) Coating process: Apply photoresist 37 to the side of silicon dioxide film 36 away from substrate 31 using a spin coater, and then dry it;

[0073] 1.4) Electron beam lithography process: The electron beam is scanned along a circular or rectangular path to expose the photoresist 37 to light;

[0074] 1.5) Development process: The photoresist 37 is developed and dried using a developer to dissolve the photoresist 37 whose molecular weight has decreased after photosensitive denaturation, and to retain the portion of photoresist 37 that needs to be retained.

[0075] 1.6) Etching process I: The silicon dioxide film 36 without photoresist 37 is etched away using a magnetic neutral loop discharge plasma etching process, so that the pattern on the silicon dioxide covered by photoresist 37 is consistent with the pattern of the retained photoresist 37, thereby forming a silicon dioxide mask 361.

[0076] 1.7) Cleaning process II: The substrate 31 was sequentially cleaned with NMP solution (N-methylpyrrolidone) and isopropanone solvent in a water bath for 15 min to 20 min and 10 min to 15 min respectively, and then dried.

[0077] 1.8) Resin Removal Process: A resist removal machine is used to remove the resist to ensure that all residual photoresist 37 on the surface of the silicon dioxide mask 361 is removed;

[0078] 1.9) Etching process II: Inductively coupled plasma etching process is adopted, and planar ion beam is used to etch the substrate 31: the area on the substrate 31 not covered by silicon dioxide mask 361 is etched, and the etching parameters are adjusted according to the sidewall tilt angle of the required pointed structure 32. The area of ​​the substrate 31 covered by silicon dioxide mask 361 is etched to obtain the pointed structure 32.

[0079] 1.10) Cleaning process III: The structure obtained in step 1.9) is ultrasonically cleaned sequentially with hydrofluoric acid, acetone, alcohol and deionized water solvent. Each ultrasonic cleaning step lasts for 15 min to 20 min, and then dried. Hydrofluoric acid is used to remove the silicon dioxide mask 361.

[0080] 1.11) Magnetron sputtering process: Metal is magnetron sputtered on each pointed structure 32 to form a metal film layer 34. During magnetron sputtering, a mask is used to ensure that no metal film layer is formed on the substrate between any adjacent pointed structures. Then, the substrate is cleaned and dried. The thickness of the metal film layer 34 is preferably 30nm-50nm.

[0081] 2) Integrating the nano-aperture combination 3 with the photosensitive array 5 mainly includes the following sub-steps:

[0082] 2.1) Fabrication process of electrical control wires for nano-tip array: Using a combination of 3D, photolithography and wire bonding technology, conductive wires 33 are soldered to each metal film layer 34, and a conductive wire 33 is led out from each metal film layer 34 of a row of nano-tip structures at the edge of the nano-tip array so as to apply voltage to the nano-tip array.

[0083] 2.2) Optical alignment process between nano-tip assembly 3 and photosensitive array 5: Align each sub-nano-tip array in the nano-tip array with a photosensitive element 51 in the photosensitive array 5, and make the nano-tip assembly 3 and the photosensitive array 5 generate near-field coupling, wherein each sub-nano-tip array includes at least one nano-tip structure.

[0084] 2.3) Packaging process: A row of conductive wires 33 of nano-tip structure at the edge of the nano-tip array is led out from the outer shell of the camera test box 4 to connect the drive signal 35. The photosensitive array 5 is installed into the camera test box 4 and the nano-tip array and the photosensitive array 5 are near-field coupled.

[0085] The determination of whether the finished infrared detector 6 based on the nano-tip array meets the parameter requirements can be summarized in the following two points: (1) Observe the uniformity of the nano-tip array and the integrity of the unit structure under a scanning electron microscope. (2) Test the electrical properties. The main operation is to apply voltage to the metal surface and the back of the substrate 31. When the resistance between them reaches the level of hundreds of ohms or even lower, it can be determined that the chip meets the parameter requirements. The above are the points that need to be noted in the preparation process of this invention.

[0086] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An infrared detector based on a nano-tip structure, comprising a camera test box and a lens holder mounted on the camera test box, characterized in that: It also includes an imaging objective, a nano-tip assembly, and a photosensitive array arranged sequentially along the optical path. The imaging objective is mounted on the lens holder, and the nano-tip assembly and the photosensitive array are respectively mounted on the camera test box. The photosensitive array is composed of multiple photosensitive elements arranged in an array. The nano-tip assembly includes a substrate and a nano-tip array disposed on the substrate. The nano-tip array includes multiple nano-tip structures arranged in an array. Each nano-tip structure includes a pointed structure and a metal film layer covering the pointed structure. Any two adjacent nano-tip structures in each row are electrically connected through conductive lines. Any two adjacent nano-tip structures in each column are electrically connected through conductive lines. Each metal film layer of a row of nano-tip structures located at the edge of the nano-tip array is connected to an outgoing wire for connecting drive and control signals. For each photosensitive element, there is a corresponding sub-nano-top array, the sub-nano-top array includes at least one nano-top structure, and the projection area of ​​the sub-nano-top array corresponding to the photosensitive element on the substrate does not exceed the projection area of ​​the photosensitive element on the substrate. The tip of each of the aforementioned pointed structures points towards the photosensitive element; The nano-tip array and the photosensitive array generate near-field coupling; For the aforementioned nano-tip array, the lateral period is 500nm-2000nm with a duty cycle of 50%-70%, and the longitudinal period is 500nm-2000nm with a duty cycle of 50%-70%. The nano-tip structure is conical or pyramidal. The duty cycle = structure size / period size. The structure size is the bottom feature size of the nano-tip structure. If the nano-tip structure is conical, it is the bottom diameter; if the nano-tip structure is pyramidal, it is the bottom side length. The lateral period is the distance between the center lines of two nano-tip structures in the lateral direction, and the longitudinal period is the distance between the center lines of two nano-tip structures in the longitudinal direction. The lateral direction is the direction of a row, and the longitudinal direction is the direction of a column.

2. The infrared detector based on a nano-tip structure according to claim 1, characterized in that, The spacing between the nano-aperture assembly and the photosensitive array is 40 nm to 300 nm to enable near-field coupling between them.

3. The infrared detector based on a nano-tip structure according to claim 1, characterized in that, The tip of the nano-tip structure is dot-shaped, spherical, mushroom-shaped, or linear.

4. The infrared detector based on a nano-tip structure according to claim 1, characterized in that, The material of the metal film layer is selected from one of aluminum, chromium, copper, silver, and gold.

5. An infrared detector based on a nano-tip structure according to claim 1, characterized in that, Each of the aforementioned pointed structures is either a conical structure or a regular pyramidal structure.

6. A method for fabricating an infrared detector based on a nano-tip structure according to any one of claims 1 to 5, characterized in that, Includes the following steps: 1) The process of creating a nano-assembly mainly includes the following sub-steps: 1.1) Cleaning process I: The substrate is ultrasonically cleaned sequentially with acetone, alcohol and deionized water, and then dried. The substrate is a silicon wafer. 1.2) Coating process: A silicon dioxide film is deposited on one surface of a cleaned substrate using plasma-enhanced chemical vapor deposition, followed by cleaning and drying. 1.3) Coating process: Apply photoresist to the side of the silicon dioxide film away from the substrate using a spin coater, and then dry it; 1.4) Electron beam lithography process: The electron beam is scanned along a circular or rectangular path to expose the photoresist to light; 1.5) Development process: The photoresist is developed and dried using a developing solution to dissolve the photoresist whose molecular weight has decreased after photosensitive denaturation, and to retain the portion of the photoresist that needs to be preserved. 1.6) Etching process I: The magnetic neutral loop discharge plasma etching process is used to etch away the silicon dioxide film without photoresist coverage, so that the pattern on the silicon dioxide covered with photoresist is consistent with the pattern of the retained photoresist, thereby forming a silicon dioxide mask. 1.7) Cleaning process II: The substrate was sequentially cleaned with NMP solution and isopropyl ketone solvent using a water bath under heating, and then dried; 1.8) Resin Removal Process: A resist removal machine is used to remove the resist to ensure that all photoresist residue on the surface of the obtained silicon dioxide mask is removed; 1.9) Etching process II: Inductively coupled plasma etching process is adopted, and planar ion beam is used to etch the substrate: the area on the substrate not covered by silicon dioxide mask is etched, and the etching parameters are adjusted according to the sidewall tilt angle of the required pointed structure. The area on the substrate covered by silicon dioxide mask is etched to obtain the pointed structure. 1.10) Cleaning process III: The structure obtained in step 1.9) is ultrasonically cleaned sequentially with hydrofluoric acid, acetone, alcohol and deionized water solvent, and then dried. Hydrofluoric acid is used to remove the silicon dioxide mask. 1.11) Magnetron sputtering process: Metal is magnetron sputtered on each pointed structure to form a metal film. During magnetron sputtering, a mask is used to ensure that no metal film is formed on the substrate between any adjacent pointed structures. Then the substrate is cleaned and dried. 2) Integrating nano-scale components with photosensitive arrays mainly includes the following sub-steps: 2.1) Fabrication process of electrical control leads for nano-tip array: Using a combination of 3D, photolithography and wire bonding technology, conductive wires are soldered to each metal film layer, and a conductive wire is led out from each metal film layer of a row of nano-tip structures at the edge of the nano-tip array to apply voltage to the nano-tip array; 2.2) Optical alignment process between nano-tip assembly and photosensitive array: Align each sub-nano-tip array in the nano-tip array with a photosensitive element in the photosensitive array, and make the nano-tip assembly and the photosensitive array near-field coupled, wherein each sub-nano-tip array includes at least one nano-tip structure. 2.3) Packaging process: A row of conductive wires of nano-tip structure at the edge of the nano-tip array is led out from the outer shell of the camera test box to connect the drive control signal. The photosensitive array is installed into the camera test box, and the nano-tip array and the photosensitive array are near-field coupled.

7. The preparation method according to claim 6, characterized in that, The thickness of the substrate is 100 nm - 300 nm.

8. The preparation method according to claim 6, characterized in that, The pointed structure is conical, with a base circle diameter of 100 nm - 1000 nm and a cone angle of 30° - 50°. The thickness of the metal film is 30 nm - 50 nm.

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