Three-dimensional gray scale structure based on low-voltage ice glue electron beam exposure and three-dimensional micro-nano hollow structure manufacturing method

Abstract

The application discloses a kind of three-dimensional gray structure based on low-voltage ice glue electron beam exposure and the manufacturing method of three-dimensional micro-nano structure, comprising: depositing an ice layer on processing surface;Then using low-energy electron beam layer-by-layer exposure, remove the ice layer of each layer specific part, finally form three-dimensional gray ice sculpture structure with specific gray pattern;Optionally, three-dimensional ice sculpture structure is deposited material using physical vapor deposition, form three-dimensional micro-nano structure;The ice layer is water ice;The low-voltage electron beam energy is lower than 5keV.The application uses the characteristics of iEBL and low-energy exposure in water ice, not only can obtain three-dimensional ice sculpture structure without support structure, but also can successfully convert gray ice sculpture into high-purity three-dimensional metal structure.This breakthrough provides potential for using water ice resist to improve nanodevice manufacturing, and establishes the key technology position of iEBL in constructing fine, pollution-free three-dimensional metal nanostructure.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanostructure manufacturing or processing, and particularly relates to a three-dimensional gray structure based on low-voltage ice glue electron beam exposure and a three-dimensional micro-nano structure manufacturing method. BACKGROUND

[0002] Due to the advantages of reducing forward scattering and reducing beam spot, high-energy electrons (higher than 30 keV) are widely used in traditional electron beam lithography (EBL) to manufacture high-resolution dense patterns. However, high-voltage EBL also has some limitations, such as low throughput, obvious proximity effect and high cost. In addition, the depth and profile of the exposed pattern are not controlled, which may cause radiation damage and complicate the direct manufacturing of three-dimensional patterns. Compared with high-energy electron exposure process, low-energy electrons (lower than 3 keV) exhibit unique advantages in patterning, especially in three-dimensional structure manufacturing. Its characteristics include lower critical dose and shorter backscattering range. On the solidified electron resist, a stepped three-dimensional nanostructure is successfully manufactured by using 3 keV. However, the potential of low-voltage EBL is still very poor, and there are still some challenges to be solved in order to be more widely used. First, when applying very low initial beam energy, the depth of the electron interaction volume will be less than the thickness of the resist, resulting in incomplete exposure. Therefore, in order to achieve the required depth of the nano pattern, the subsequent deposition or etching step usually requires additional processes. In addition, with the decrease of acceleration voltage, the forward scattering of electrons increases significantly, which is widely considered as the main factor limiting the resolution. Therefore, solutions combining line width control and direct formation of gray pattern need further research.

[0003] Unlike traditional photoresists, ice layers / films exhibit greater applicability in low-energy electron exposure. Existing research has shown that using 1keV electron binding to protect ice layers can significantly reduce radiation damage to sensitive materials. Ice-assisted electron beam lithography (iEBL) has also achieved layered 3D printing using organic ice and water ice, offering advantages such as in-situ alignment, contamination-free processing, no development required, and time savings, making it more competitive than focused electron beam induced deposition (FEBID) and scanning probe lithography (SPL). Although water ice, as a positive photoresist, can fabricate nanostructures, its ability to fabricate 3D grayscale structures has not been fully explored. Furthermore, maintaining ice structures requires additional deposition processes, making the achievement of high-resolution, self-supporting 3D structures challenging. FEBID can fabricate small and delicate 3D metallic structures (typically 20 to 60 nm), but due to the inevitable incorporation of impurities such as carbon, FEBID faces difficulties in fabricating high-purity 3D metallic structures. These impurities may weaken or mask the properties of the target material. Since many applications are closely related to the performance of deposited materials, research on high-purity structures is crucial for ensuring device performance. Summary of the Invention

[0004] This invention provides a method for manufacturing three-dimensional grayscale structures and three-dimensional micro / nano hollow structures based on low-voltage ice gel electron beam exposure. This method changes the traditional approach of three-dimensional printing that requires supporting materials in the processing of three-dimensional nanostructures. Instead, it combines multiple exposures with low-energy electron beams to achieve the processing of three-dimensional grayscale structures on ice layers / ice films. This eliminates the need for additional support to maintain the structure, improves the resolution of the three-dimensional grayscale structure, and avoids the problem of impurity contamination.

[0005] A method for manufacturing a three-dimensional grayscale structure based on low-voltage ice gel electron beam exposure includes: depositing an ice layer on a processing surface; then using a low-energy electron beam for layer-by-layer exposure to remove the ice layer from specific parts of each layer, ultimately forming a three-dimensional ice sculpture structure with a specific grayscale pattern, i.e., a three-dimensional grayscale structure; wherein the ice layer is water ice; and the low-voltage electron beam energy is below 5keV.

[0006] Furthermore, the number of electron beam layers and the area to be exposed in each layer are determined by the grayscale value corresponding to the three-dimensional grayscale structure.

[0007] Furthermore, before processing, the grayscale image corresponding to the three-dimensional ice sculpture structure is divided into multiple black and white sub-images; when using low-energy electron beams for layered exposure, each layer corresponds to a black and white sub-image, with the black area corresponding to the exposure area, while the white area is not exposed.

[0008] A method for fabricating three-dimensional micro / nano hollow structures based on ice lithography using low-voltage electron beam exposure includes: fabricating a three-dimensional ice sculpture structure with a specific pattern using the aforementioned three-dimensional grayscale structure manufacturing method; depositing a thin film of material on the three-dimensional ice sculpture structure; and sublimating the three-dimensional ice sculpture structure by heating to obtain the corresponding three-dimensional micro / nano hollow structure.

[0009] It should be noted that the "grayscale" structure described in this article does not refer to a two-dimensional grayscale planar image, but rather a three-dimensional structure composed of "pixels" at different depths. This three-dimensional structure is a three-dimensional ice sculpture structure composed of ice points of varying heights (depths). Of course, there is an inherent correspondence between this three-dimensional ice sculpture structure and its corresponding two-dimensional image. Furthermore, before creating the three-dimensional grayscale structure, the corresponding two-dimensional grayscale image or depth image is divided into multiple black and white sub-images based on its grayscale values ​​(for example, using MATLAB software (or other software capable of recognizing image grayscale values) to perform a custom step division of the image's grayscale, exporting images from different grayscale ranges to form "sub-images"). The black areas in the sub-images correspond to the exposed areas, while the white areas are not exposed. The number of sub-images can be set according to the selected image; for images with high precision requirements or a wide grayscale value range, multiple sub-images can be set.

[0010] Furthermore, a method for fabricating three-dimensional grayscale structures / three-dimensional micro / nano hollow structures using low-voltage electron beam exposure based on ice lithography includes the following steps:

[0011] (1) Ice deposition: Depositing a layer of ice on the processing surface;

[0012] (2) Ice layer patterning: Using a low-voltage electron beam, specific parts of the ice layer are removed layer by layer multiple times to finally form a three-dimensional ice sculpture with a specific grayscale pattern.

[0013] (3) Material deposition (optional): Deposit a thin film of material on the surface of the sample to be processed, including the portion of the thin film deposited on the ice mask and the portion of the thin film deposited directly on the surface of the sample to be processed;

[0014] (4) Dry stripping (optional): Heating causes the ice mask to sublimate, and the remaining material film (i.e. the part of the material film directly deposited on the sample to be processed) forms the micro-nano structure corresponding to the ice sculpture on the sample to be processed.

[0015] Furthermore, in the step of removing a specific portion of the ice layer multiple times using a low-voltage electron beam, the number of layers (or the corresponding number of sub-images) can be selected as 2-50 sub-images, preferably 5-30. The number of sub-images corresponds to the number of electron beam exposure layers. The thickness of each layer is preferably less than 150 nm; more preferably 5-150 nm; even more preferably 5-100 nm; even more preferably 5-60 nm; and more specifically preferably 5-30 nm.

[0016] Using the method of the present invention, after each electron beam exposure process, the linewidth is less than 50 nm, further less than 30 nm; more preferably, the linewidth is 5-30 nm.

[0017] Furthermore, preferably, the total dose range of the electron beam exposure area is 0.1 C / cm². 2 -10C / cm 2 Between. For example, it could be 0.2C / cm. 2 0.5C / cm 2 1C / cm 2 2C / cm 2 3C / cm 2 4C / cm 2 5C / cm 2 6C / cm 2 7C / cm 2 8C / cm 2 9C / cm 2 10C / cm 2 And the specific point values ​​between the above values, due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range. Preferably, it is 1C / cm. 2 -4C / cm 2 The dose per layer can be determined by the total dose / number of layers, and is generally preferred to be 0.05–0.5 C / cm. 2 .

[0018] Furthermore, the low-voltage electron beam energy is below 4.5 keV; more preferably below 3.5 keV; specifically, the low-voltage electron beam energy is 0.3 keV-1 keV.

[0019] In this invention, the total thickness of the ice film is 20–500 nm, further limited to 25–500 nm. More preferably, it is 50–300 nm.

[0020] This invention can form an ice film on a planar substrate or the surface of a sample to be processed (planar or non-planar), without specifying the substrate material; it can be a conductive or non-conductive substrate. The main components of the planar substrate material are any one or more combinations of Au, Ag, Cu, Al, Pt, Pd, Mn, Fe, Co, Ni, Zn, Cd, Ge, Sn, Pb, Sb, Bi, Si, Ge, GaN, GaAs, GaP, ITO, InP, InAs, ZnS, ZnSe, CdS, CdSe, ZnO, TiO2, MgO, CdO, Al2O3, SiO2, or Si3N4. For example, Al2O3 substrates, Si wafer substrates, and Si substrates with a 200-300 nm thick SiO2 layer on the surface can be selected.

[0021] In step (3), the material is a metal, and the metal thickness can be selected from 20-500 nm, preferably 30-100 nm. The type of metal is selected from one or more of gold, silver, copper, chromium, etc., which can be physical vapor deposition.

[0022] This invention can be performed using a scanning electron microscope. The scanning electron microscope is selected from one of thermal field emission scanning electron microscopy, cold field emission scanning electron microscopy, and environmental scanning electron microscopy. In this invention, the electron beam exposure time can be determined according to the actual requirements of the pattern size to be etched or processed. The specific shape of the pattern to be processed is controlled by inputting data information from the scanning electron microscope.

[0023] In this invention, the ice layer is obtained at a low temperature, which is the sublimation temperature of water vapor in its amorphous crystalline state at the corresponding pressure or lower. Preferably, the low temperature range is 100K-140K. Examples include 100K, 110K, 120K, 130K, and 140K, as well as specific values ​​between these values. For space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range. Preferably, the low temperature range is 120K-140K.

[0024] This technology, based on low-voltage ice gel electron beam lithography (iEBL) using water ice as a resist, achieves the fabrication of high-resolution, pollution-free three-dimensional grayscale patterns and three-dimensional micro / nano hollow structures, demonstrating broad application prospects. It is applicable to fields such as nano-optical devices, quantum devices, and biosensors; it can generate complex grayscale patterns without support, which can be used in optical components such as microlens arrays; and its ability to transform ice sculptures into high-purity three-dimensional metal structures provides a new solution for the fabrication of micromechanical systems (MEMS) and advanced memory devices. Furthermore, this technology is environmentally friendly, energy-efficient, and aligns with the development trend of sustainable manufacturing, possessing significant research and industrialization value.

[0025] Compared to existing technologies, we propose an ultra-low energy electron beam nanofabrication strategy based on ice-assisted electron beam lithography (iEBL). This method focuses particularly on the fabrication of grayscale patterns and three-dimensional metallic nanostructures. By employing a low-energy electron beam, this strategy overcomes the limitations imposed by the electron interaction volume, enabling more precise control over pattern depth. Figure 1 Furthermore, low-energy electron beams based on ice-assisted electron beam lithography (iEBL) can be used to fabricate linear patterns with resolutions below 30 nm, as well as grayscale patterns with up to 30 layers and single-layer thicknesses as low as 10 nm, far exceeding the values ​​achievable by traditional techniques. More importantly, utilizing the properties of iEBL and low-energy exposure in water ice, we successfully transformed grayscale ice sculptures into high-purity three-dimensional metallic structures. This breakthrough provides potential for improving nanodevice fabrication using water ice resists and establishes iEBL's key technological position in constructing fine, pollution-free three-dimensional metallic nanostructures. Attached Figure Description

[0026] Figure 1 A comparison of the step exposure mechanism for high-voltage (10keV) and low-energy (1keV) electrons.

[0027] Figure 2 SEM images showing the results of the critical size study for electron beam exposure at different voltages (the inset in the circle is a magnified SEM image corresponding to 0.3 keV).

[0028] Figure 3 The image shows the SEM results of the study on the fabrication process of the grayscale koi carp structure and the influence of electron beam energy and exposure strategy on grayscale lithography.

[0029] Figure 4 This is a SEM image of the continuous grayscale and stepped ice structure based on a checkerboard pattern.

[0030] Figure 5 Continuous grayscale and stepped ice structure SEM images of different sloping structures.

[0031] Figure 6 A schematic diagram of the process of creating a three-dimensional hollow gold structure using continuous grayscale and stepped ice sculpture, where 1: ice layer; 2: metal layer. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings:

[0033] A method for fabricating three-dimensional grayscale structures or three-dimensional micro / nano hollow structures based on low-voltage gel electron beam exposure can be referenced. Figure 6 As shown, it includes the following steps:

[0034] (1) Deposit a layer of ice on the processing surface;

[0035] (2) Then, using low-voltage electron beam exposure, specific ice layers are removed layer by layer to ultimately form a three-dimensional ice sculpture structure with a specific pattern. Figure 3 (a) represents a three-dimensional grayscale structure; the ice layer is water ice.

[0036] (3) Material deposition (optional): Depositing a thin film of material on the surface of the sample to be processed, including the portion of the thin film deposited on the ice mask and the portion of the thin film deposited directly on the surface of the sample to be processed. Figure 3 (b)

[0037] (4) Dry stripping (optional): Heating causes the ice mask to sublimate, and the remaining material film (i.e., the part of the material film directly deposited on the sample surface to be processed) forms a micro-nano hollow structure corresponding to the ice sculpture on the sample surface to be processed. Figure 3 (c) and (d)).

[0038] For the fabrication of complex 3D patterns, before electron beam exposure, the image is divided into multiple black and white sub-images based on its grayscale values. Specifically, before processing in step (1), the image is first divided into multiple black and white sub-images based on the grayscale values ​​of the depth image or grayscale image of the target 3D structure (for example, the grayscale of the image can be customized using MATLAB to create a step-by-step division, and images of different grayscale ranges can be exported separately to form "sub-images"). The black areas in the sub-images correspond to the exposure areas, while the white areas are not exposed. The number of sub-images can be set according to the selected image, ranging from 2 to 50.

[0039] In actual processing, the number of sub-patterns is determined based on the characteristics of the pattern; considering the three-dimensional structural features and accuracy requirements, the total ice layer thickness and the total number of layers are determined, and then the layer thickness of each layer is determined. Each sub-pattern corresponds to one exposure operation. Layer thickness and other parameters can be determined according to actual accuracy requirements. Generally, a layer thickness of 5-30 nm is selected. The electron beam voltage is selected to be 1 keV or below. Other parameters follow conventional schemes.

[0040] The deposition of the ice layer in step (1) can be completed at low temperatures. That is, the ice layer is formed by water vapor deposition at low temperatures. In actual operation, the substrate is placed in a scanning electron microscope, and the sample stage temperature is lowered to 135K by a cooling device. Water vapor is deposited on the sample surface in the vapor phase to form a water ice film of the required thickness. The electronic book exposure operation can be performed using a scanning electron microscope, which is selected from thermal field emission scanning electron microscopes, cold field emission scanning electron microscopes, and environmental scanning electron microscopes. In this embodiment, we use a cold field emission scanning electron microscope for processing.

[0041] Figures 2 to 6 For practical research on the method of the present invention:

[0042] Figure 2 As shown, the overall thickness of the ice layer is approximately 250 nm. The three images correspond to beam energies of 300 eV, 600 eV, and 1 keV, respectively. In each image, the voltammetry gradually increases from left to right, with an increase step of 0.12 C / cm. 2 The total dose was 1.2 C / cm. 2 The circular inset corresponds to a magnified SEM image of the sample stage at 300 eV with the stage tilted. The scale bar is 2 μm.

[0043] Critical dimension and critical dose are important parameters in EBL nanofabrication. Figure 2 In the diagram, the critical dimensions are shown at different accelerating voltages, while ice thickness, electron beam current, and working distance remain consistent. Gradually increasing doses are applied to the linear array from left to right. The dose required to completely remove the ice is determined by tilting the sample stage by 15° and observing the depth of the cracks at the line ends. As shown in the inset, the lighter color at the bottom of the two lines on the left indicates the presence of residual ice. The line within the dashed circle on the far right is fully exposed; its width is defined as the critical dimension, and the corresponding dose is the critical dose. Figure 2 The results show that even in ice layers / films, 1keV electrons can still fabricate structures with linewidths less than 30nm, which is superior to other resists such as PMMA, HSQ, or ZEP-520, whose resolution at 1keV exceeds 50nm. The pattern resolution can be further improved by reducing the thickness of the ice resist.

[0044] Figure 3 (a) is a schematic diagram of the fabrication of the continuous grayscale koi carp structure, and (b)-(e) are the results of the influence of electron beam energy and exposure strategy on grayscale lithography. In (b), each small sector is exposed using 5keV electrons in a single exposure, with the dose varying according to the grayscale value (the dose for the sector with the higher grayscale value is 1.3 C / cm). 2 The lowest sector corresponds to a dose of 1.3 / 12 = 0.108 C / cm. 2 (c) A single exposure using 1keV electrons, with the dose remaining constant. (d) Twelve exposures using 5keV electrons for each sector, with the total dose for each sector remaining constant. The layer dose and number of exposures are determined based on the number of sub-images that are black at the corresponding positions. (e) Twelve exposures using 1keV electrons, as above. The scale bars in (b)-(e) are all 1μm. The ice layer thickness is 300nm, and the total dose at the position with the highest grayscale value is 1.3C / cm. 2 .

[0045] Before actual processing, MATLAB software was used to... Figure 3The koi image shown in (a) is divided into 15 sub-images to achieve a continuous grayscale structure in the ice, as... Figure 3 As shown in the right image of (a) in the middle section. During the actual processing, electron beam exposure was performed on different layers corresponding to the 15 black and white sub-images, with the black areas corresponding to the exposed areas and the white areas remaining unexposed. Ultimately, we obtained micrometer-scale ice koi carp, whose SEM image is shown in the lower left corner.

[0046] Meanwhile, to verify the advantages of our exposure strategy, we compared 12-layer grayscale fan-shaped patterns fabricated using different beam energies (voltage, i.e., 1 keV and 5 keV) and exposure times (1 and 12). Under a 5 keV electron beam ( Figure 3 In (b) and (d), regardless of the exposure method used, an inhomogeneous interface is observed in the partially exposed ice layer. Conversely, when using a 1keV electron beam ( Figure 3 In (c) and (e)), the two exposure methods perform similarly at low regional doses. However, as the dose increases (corresponding to an increase in pattern grayscale), the pattern produced by a single exposure ( Figure 3 c) The boundaries become blurred, affecting the fabrication of 3D multilayer nanostructures. In contrast, the multiple exposure strategy ( Figure 3 e) It can effectively alleviate charge accumulation and generate a stepped structure with clear boundaries.

[0047] Figure 4 (a)-(d) show the resolution limit of grayscale ice patterns. Figure 4 In the images, (a) and (b) are grid arrays. (a) shows a checkerboard pattern with a side length of 600 nm fabricated on a 300 nm thick ice layer, containing six different heights (six black and white sub-patterns, six exposures, using a 1 keV electron beam). (b) has the same structure as (a), but each square has a side length of 500 nm. (c) shows a 30-layer inverted pyramid structure fabricated on a 300 nm thick ice layer (30 black and white sub-patterns, 30 exposures, using a 1 keV electron beam). (d) shows a regular pyramid structure with the same dimensions as (c). The scale bar in (a) and (b) is 1 μm, and the scale bar in (c) and (d) is 2 μm. The total dose is 1.3 C / cm. 2 . Figure 4 Images (c)-(d) show a 30-layer multilayer structure with a step size of 300 nm. The boundaries of each layer are clearly visible under SEM.

[0048] Our exposure strategy also supports the fabrication of ramp nanostructures. Figure 5 (a) and (b) show stepped ramp structures with trapezoidal cross sections. Figure 5In the images, (a) is a grayscale SEM image of a trapezoidal cross-section with a lateral dimension of 500 nm. (b) is a slope with a width of 1 μm. (c) is a sloped grating with five periods, each slope being 1 μm wide. (d) is a structure consisting of two slopes, each with a lateral dimension of 500 nm. (e) is a double-slope structure with slopes of 1000 nm and 500 nm on the two sides, respectively. (f) is a tilted grating composed of elements from (e). The ice layer thickness is 300 nm, the electron beam energy is 1 keV, and the total dose is 1.3 C / cm. 2 When the step size is set to 100 nm or smaller, the boundary becomes indistinguishable under SEM observation, and the stepped structure gradually evolves into a tilted plane. Figure 5 (c) illustrates a grating structure including continuous slopes. Furthermore, Figure 5 Images (d)-(f) demonstrate double-sloping structures with lateral dimension ratios of 1:1 and 1:2. In particular... Figure 5 Figure (f) shows the fabrication of a 20-layer array of sloping structures with two sloping sides.

[0049] Utilizing the superior slope structure generated through low-energy iEBL, we successfully fabricated three-dimensional hollow gold structures, including hemispherical and roof structures. The fabrication process is as follows: Figure 6 As shown. Figure 6 A schematic diagram of the process for fabricating a three-dimensional hollow gold structure using continuous grayscale and stepped ice sculpting. (a) Continuous grayscale exposure is performed on an ice substrate with an ice layer thickness of 500 nm and a total dose of 1.6 C / cm. 2 (a) Evaporation of metallic gold (Au) onto the exposed ice structure; (c) Heating of the entire sample; (d) Structure fabrication via a one-step stripping process. Illustrations of each step show SEM micrographs of the hemispherical and roof structures. (e)–(f) Focused ion beam (FIB) cutting reveals the internal cavities of the hollow gold structure. (g)–(h) Atomic force microscopy (AFM) images and their corresponding height distribution maps of the hollow gold structure. Scale bar: 500 nm. After generating the structure via grayscale iEBL (… Figure 6 The sample underwent thermal evaporation, depositing a 40nm thick layer of gold (Au) onto the ice structure. Figure 6 (b)). Further extending this process, the metal thickness can be selected from 20-500 nm, preferably 30-100 nm. After metallization, the sample is restored to room temperature and then subjected to a simple one-step exfoliation process. Figure 6 d) The final three-dimensional hollow gold structure is easily obtained. Since the metal is directly vapor-deposited via physical vapor deposition, the purity of the structure is theoretically equal to that of the evaporation source. Furthermore, this strategy has no restrictions on the choice of metal. To demonstrate the hollow structure in detail, the hemisphere and roof structures were cut using focused ion beam technology. Figure 6(ef) revealed a clear outline of the internal cavity. Furthermore, the fabrication process was extended to generate an array of these hollow structures, and their morphology was analyzed using AFM. Figure 6 gh).

[0050] In summary, we propose a novel nanofabrication strategy based on ice-assisted electron beam lithography (iEBL), with a particular focus on the fabrication of grayscale patterns and three-dimensional metallic nanostructures. The application of low-energy electron beams in iEBL overcomes the limitation of electron interaction volume on pattern depth. Experimental results fully demonstrate that a 1keV electron beam exhibits higher exposure efficiency, despite a slight increase in the critical size. We present a revolutionary method for fabricating grayscale nanopatterns, successfully realizing continuous grayscale and stepped ice structures (e.g., koi fish, pyramids, and sloping ice sculptures), with a maximum layer count of up to 30 layers, exceeding the layer count achieved by PMMA-based grayscale patterns in the literature. Furthermore, through an optimized low-energy iEBL strategy, we successfully fabricated complex three-dimensional hollow metallic structures by converting grayscale ice sculptures. This highlights the potential of low-energy grayscale water ice iEBL in the field of complex three-dimensional nanofabrication.

Claims

1. A method for manufacturing a three-dimensional gray scale structure based on low voltage ice gel electron beam exposure, characterized by, The method comprises the following steps: Depositing an ice layer on a processing surface; then using a low-voltage electron beam to perform layer-by-layer exposure to remove the ice layer in specific parts of each layer, and finally form a three-dimensional ice sculpture structure with a specific gray pattern; the ice layer is water ice; the low-voltage electron beam has an energy lower than 5 keV.

2. The method of claim 1, wherein the low-voltage ice gel e-beam exposure based three-dimensional gray scale structure manufacturing method is characterized by, The number of layers of the layer-by-layer exposure and the area of each layer that needs to be exposed are determined by the gray values corresponding to the three-dimensional gray structure.

3. The method of claim 1, wherein the low-voltage ice gel e-beam exposure based three-dimensional gray scale structure manufacturing method is characterized by, Before processing, the gray pattern corresponding to the three-dimensional ice sculpture structure is divided into multiple black-and-white sub-patterns; during the layer-by-layer exposure using a low-voltage electron beam, each layer corresponds to a black-and-white sub-pattern, and the black area corresponds to the exposed area, while the white area is not exposed.

4. The method of claim 2, wherein the low-voltage ice gel e-beam exposure based three-dimensional gray scale structure manufacturing method is characterized by, The number of layers is 2-50.

5. The method of claim 1, wherein the low-voltage ice gel e-beam exposure based three-dimensional gray scale structure manufacturing method is characterized by, The thickness of each layer is 5-150 nm.

6. The method of claim 1, wherein the low-voltage ice gel e-beam exposure based three-dimensional gray scale structure manufacturing method is characterized by, The energy of the low-voltage electron beam is 0.3 keV-1 keV.

7. The method of claim 1, wherein the low-voltage ice gel e-beam exposure based three-dimensional gray scale structure manufacturing method is characterized by, When the low-voltage electron beam is used for layer-by-layer exposure, the single-layer exposure dose is 0.05-0.5 C / cm 2 .

8. A method for processing three-dimensional micro-nano hollow structure based on low-voltage electron beam exposure of ice carving, characterized in that, The method comprises the following steps: Using the method for manufacturing a three-dimensional gray structure according to any one of claims 1-7 to process a three-dimensional ice sculpture structure; Then depositing a material film on the three-dimensional ice sculpture structure; Raising the temperature of the three-dimensional ice sculpture structure to sublimate and obtain a three-dimensional micro-nano hollow structure corresponding to the deposited material.

9. The method according to claim 8, wherein, The material is selected from one or more of gold, silver, copper, and chromium, and the material film is obtained by physical vapor deposition.

10. The method of claim 8, wherein the method is a method of processing three-dimensional micro-nano hollow structure based on ice-etching and low-voltage electron beam exposure, characterized in that, The thickness of the material film is 20-500 nm.

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