Method for producing 3D printed objects using solidified organic matter and a focused electron beam

Abstract

The present invention relates to a method for 3D printing a digital representation of a 3D structure. The method includes the steps of: solidifying vapor on the surface of a cooled substrate to form a first solidified organic layer; exposing at least a portion of the first solidified organic layer with at least one electron beam to form one or more voxels within the first solidified organic layer; solidifying vapor on the surface of the first solidified organic layer to form a second solidified organic layer; exposing at least a portion of the second solidified organic layer with at least one electron beam to form one or more voxels within the second solidified organic layer; and transferring the first and second solidified organic layers to ambient conditions to evaporate the unexposed areas of the first and second solidified organic layers. In the voxel formation step in the first solidified organic layer, one or more voxels are arranged according to a predetermined first pattern and remain substantially undamaged under ambient conditions. In the step in the second solidified organic layer, one or more voxels are arranged according to a predetermined second pattern and remain substantially undamaged under ambient conditions. The predetermined first and second patterns are defined by first and second G codes obtained from the digital representation of the 3D structure to be 3D printed, respectively. Furthermore, the present invention relates to a method of 3D printing at room temperature and a 3D printer.

Description

[Technical Field]

[0001] This invention relates to a layer-by-layer digital process using a thin film of solidified organic vapor as the starting material. In this process, a focused electron beam is used to chemically crosslink the solidified organic material (organic ice) and convert it into a solid structure. Furthermore, this process shares the same software and CAD database as industrial 3D printing. Based on simulations of electron-matter interactions, the crosslinking thickness can be controlled in the range of 250 nm to 2 μm. The fabricated 3D printed structure consists of up to 500 layers of thin films of organic vapor, with a minimum structural dimension of 550 nm in width. The digital process of this invention complements two-photon lithography in three respects: (i) it is applicable to chemical substances other than photopolymers; (ii) because it does not involve immersion in liquid resin, it is possible to print delicate suspended structures and tube structures without being destroyed by interfacial forces of resin remaining in the cavity; and (iii) it is possible to print hanging structures without using a sacrificial support. [Background technology]

[0002] Additive manufacturing (AM), or 3D printing, is a foundational technology that has revolutionized mechanical engineering and production by providing digital methods for creating products that were previously impossible to manufacture. Recent research has had a significant impact on our fundamental understanding of production speed, photochemistry, advanced alloys, and the science and processes of AM.

[0003] In submicrometer-range AM, two-photon lithography (TPL) has achieved great success due to the inherent characteristics of photon-based AM processes and advancements in photopolymerization chemistry. TPL printing speeds have been significantly improved by advancements in multibeam technology. The photopolymerization process is an amplified chemical reaction, where each photon initiates a local polymerization reaction. This polymerization reaction is terminated by a chemical inhibitor.

[0004] One of the drawbacks of polymerization-based TPL and AM is that they rely on extremely delicate photoinitiation, polymerization, and termination reaction chemistry that must take place within sub-micrometer-sized voxels. Focused electron beam-induced deposition (FEBID) takes full advantage of the benefits of organic chemistry and makes it possible to 3D print metals, magnetic materials, and superconductors at the nanoscale.

[0005] FEBID is an electron-gas-surface interaction-based process that allows for control at the monolayer level, but comes with the trade-off of being slow. While FEBID enables 3D nanostructures, powder-based electron beam additive manufacturing (EBAM) technology is the gold standard for metal AM. The resolution of EBAM is 20 μm.

[0006] Ice lithography (IL) is a fundamentally different technique from FEBID and EBAM. In IL, water vapor is condensed on a cooled substrate to form a patterned ice thin film using an electron beam, and metal nanostructures are fabricated by lift-off. Multiple ice layers are used to fabricate metal suspension structures.

[0007] Previous studies have shown that solidified organic materials such as alcohols, aromatic compounds, and alkanes, as well as solidified organometallic materials, can be patterned by electron beam crosslinking reactions. This makes IL applicable to chemistry beyond the photopolymers required in TPL and stereolithography, for example. IL is more than four orders of magnitude faster than FEBID because electrons interact with the entire thin film of the solidified material. Patterns with a linewidth of 4 nm, accompanied by angstrom-level line-edge roughness and a surface roughness of 1 nm, have been reported. The ultimate resolution of IL is limited by molecular size and the probabilistic nature of electron-solidified material interactions. The thickness of the solidified organic material can be controlled with an accuracy of 10 nm. IL can also be used for patterning on 3D objects. A drawback of conventional IL processes is the limited number of solidified organic material layers.

[0008] Our research demonstrates an example of manually printing a 2.5-dimensional structure consisting of three layers of solidified organic material using the EBL process. Another research group 3D printed four layers of solidified material to show a hanging structure. Both studies utilize the EBL process and its framework, which are designed for 2D and grayscale patterning.

[0009] However, TPL photopolymers are toxic, and IL chemicals, while harmless, are based on petrochemicals. Therefore, there is a need for nanoscale 3D printing methods that move away from toxic substances and petrochemicals, and instead use low-toxicity, renewable, and sustainable materials. [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] An object of the embodiments of the present invention is to provide a method for producing a 3D printed object in a solidified organic material using multiple solidified organic layers.

[0011] A further object of the embodiments of the present invention is to provide a method for producing complex 3D printed objects in a solidified organic material.

[0012] A further objective is to provide a scanning electron beam configuration that has a low carbon footprint, is inexpensive, and offers improved sustainability compared to current methods. [Means for solving the problem]

[0013] The above objective is achieved, in the first embodiment, by providing a method for 3D printing a digital representation of a 3D structure.

[0014] This method is (a) A step in which vapor is solidified on the surface of the cooled substrate to form a first solidified organic layer, (b) a step of exposing at least a portion of the first solidified organic layer with at least one electron beam to form one or more voxels in the first solidified organic layer, (c) a step in which vapor is solidified on the surface of the first solidified organic layer to form a second solidified organic layer, (d) a step of exposing at least a portion of the second solidified organic layer with at least one electron beam to form one or more voxels in the second solidified organic layer, (e) a step of transferring the first solidified organic layer and the second solidified organic layer to ambient conditions in order to evaporate the unexposed areas of the first solidified organic layer and the second solidified organic layer, Includes. In step (b), the one or more voxels are arranged according to a predetermined first pattern and remain substantially undamaged under ambient conditions. In step (d), the one or more voxels are arranged according to a predetermined second pattern and remain substantially undamaged under ambient conditions. The predetermined first and second patterns are defined by a first G code and a second G code, respectively, obtained from a digital representation of the 3D structure to be 3D printed.

[0015] Thus, the present invention relates to a method of 3D printing a digital representation or model of a 3D structure. The present invention is advantageous in that the use of G-code enables the use of a very large number of layers of solidified organic matter, for example, hundreds of layers of solidified organic matter.

[0016] As used herein, "condensing" should be understood to mean changing a compound from a fluid phase to a solid phase. Also, "essentially intact" should be understood to mean substantially no change. Thus, "one or more voxels remain essentially intact" means that when exposed to room temperature conditions, for example, room temperature in the range of 15 to 25 °C, the one or more voxels do not change in both chemical properties and physical state.

[0017] As used herein, G-code should be understood as (x,y) coordinates that define a predetermined pattern that at least one electron beam should follow in a given z-plane. The entire G-code file is generated by slicing the 3D structure to be 3D printed into a stacked arrangement of layers consisting of (x,y) coordinates. As used herein, Hewlett Packard Graphics Language (HPGL) or a similar approach is also treated as G-code because it is a vector-based graphics tool suitable for printers, plotters, other output devices, and further for the control of electron beams.

[0018] As described above, the present invention is advantageous in that the use of G-code enables the use of a very large number of layers of solidified organic matter, for example, hundreds of layers of solidified organic matter.

[0019] Therefore, the method includes forming an additional layer of solidified organic matter by the step (a); exposing each of the additional layers of solidified organic matter by the step (b); evaporating the unexposed regions of the additional layers of solidified organic matter by the step (e); It may also include the following.

[0020] In practice, the above method is The process of forming at least 10 additional solidified organic layers, for example, at least 50 additional solidified organic layers, for example, at least 75 additional solidified organic layers, for example, at least 100 additional solidified organic layers, for example, at least 150 additional solidified organic layers, for example, at least 200 additional solidified organic layers, for example, at least 300 additional solidified organic layers, for example, at least 400 additional solidified organic layers, for example, at least 500 additional solidified organic layers by the process of (a) above, The above step (b) involves exposing each of the additional solidified organic layers, The above step (e) involves evaporating the unexposed region of the additional solidified organic material layer, It may also include the following.

[0021] In general, the solidified organic layer may contain different chemical compositions.

[0022] Therefore, as an example, the first solidified organic layer may have a first chemical composition, the second solidified organic layer may have a second chemical composition, and the first chemical composition and the second chemical composition may be different.

[0023] The one or more voxels may have dimensions between 10 nm and 10,000 nm in the plane of the first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer, for example, dimensions between 10 nm and 1,000 nm, for example, dimensions between 100 nm and 500 nm.

[0024] In this specification, “plane” should be understood as the extent of the solidified organic layer that extends substantially perpendicular to the direction of growth during vapor solidification.

[0025] Candidate vapor materials must be able to solidify under specified conditions. Typically, vapors contain molecules with a molecular weight of less than 1000 daltons. Vapors can be generated from one or more compounds described in the following literature: Landolt-Bornstein: New Series, Neue Serie Group 4 Vol. 20a: Vapor Pressure of Chemicals, Landolt-Bornstein: New Series, Neue Serie Group 4 Vol. 20b: Vapor Pressure of Chemicals, Landolt-Bornstein: New Series, Neue Serie Group 4 Vol. 20c: Vapor Pressure of Chemicals and National Institute of Standards, and Technology NIST WebBook.

[0026] Of the compounds listed in the above literature, those used as potential vapor candidates must satisfy several conditions. These conditions may include appropriate vapor pressures at 10K, 80K, or 150K, appropriate vapor pressures at room temperature, and appropriate vapor pressures at, for example, 100°C. These vapor pressures can be calculated using the Antoine formula. Water may serve as a baseline for all three pressure values. The vapor pressure at 150K should be low, preferably the same as or lower than the vapor pressure of water at 150K, which is 4.7e-10 Torr. Furthermore, this vapor pressure must be lower than the vacuum pressure (5e-6 Torr) in the chamber where the compound is frozen. The vapor pressure of the candidate compound at room temperature (298K) should be close to the vapor pressure of water, which is 23 Torr, preferably in the range between 1 Torr and 760 Torr. If the vapor pressure of the compound at room temperature is too low, it may become impossible to heat the compound to a higher temperature (e.g., 100°C) to increase the vapor pressure and inject it into the chamber.

[0027] Furthermore, potential vapor candidates may belong to specific chemical classes. These classes include hydrocarbons (C6-C6). 16 The compounds may also include sulfur-containing compounds, halogen-containing compounds, oxygen-containing compounds, nitrogen-containing compounds, monomers, and ALD and CVD precursors for metal layers. Table 1 below shows some compounds selected from these classes.

[0028] [Table 1]

[0029] Important vapor parameters related to the formation of the solidified organic layer include: 1) vapor pressure at 150 K, 2) vapor pressure at 298 K, 3) triple point, 4) ionization cross-section at 10 keV, and 5) ionization cross-section at 50 keV. Parameters such as vapor pressure at 150 K, vapor pressure at room temperature (298 K), and vapor pressure at 100 °C are shown in Table 1 above. The vapor pressure value is estimated by the Antoine equation. The reaction product between vapor and electron beam may be solid.

[0030] Typically, vapor can be introduced into a high-vacuum chamber via a gas injection system. This gas injection system may include nozzles designed to control the vapor flow rate so that the vapor enters the vacuum chamber. Upon contact with a cooled substrate, the vapor solidifies to form a solidified organic layer.

[0031] The substrate may have a flat surface or a non-flat surface. Even if the substrate surface is non-flat, the solidified organic layer adheres to the surface due to good adhesion between the substrate surface and the attached vapor. Typically, the substrate may include a wafer. The wafer may be, for example, a standard 100 mm diameter wafer. The wafer material may be silicon or another material.

[0032] The substrate may be cooled to a temperature below 200K, for example below 170K, for example below 150K, for example below 130K, for example below 110K, for example below 90K, for example around 80K.

[0033] Please note that the substrate can be cooled down to, for example, 10K, while it can also be heated up to 350K.

[0034] For cooling the substrate, a cryogenic system placed inside a high-vacuum chamber may be used. Typically, a high-vacuum chamber is approximately 10 -6 It operates at a pressure of Torr. The steam preferably has a pressure of about 0.1 to 10 Torr at room temperature so that it can be introduced into the vacuum chamber via a gas injection system.

[0035] The cryogenic system may include a copper base that is cooled by thermal contact through an oxygen-free copper braid. The copper braid may be fixed to the cryogenic stage by soldering or clamping. The other end of the copper blade may be fixed to a copper rod by soldering or clamping. The copper rod may be immersed in liquid nitrogen stored in an external liquid nitrogen (LN2) dewar.

[0036] After solidification, the solidified organic layer preferably has a vapor pressure lower than the pressure in the high-vacuum chamber to prevent sublimation. The thickness of the solidified organic layer can be adjusted by both temperature control of the low-temperature stage and control of the amount of vapor introduced into the vacuum chamber.

[0037] The first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer are composed of solidified diesel (C9H 20 It may have a layer of )

[0038] Alternatively, or in combination therewith, the first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer may have a renewable chemical, a layer of solidified ethanol, a layer of solidified nonane, and / or a layer of solidified fatty acids derived from vegetable oil.

[0039] An electron beam is understood to be a stable and well-focused beam of electrons with high current and high energy. The electron beam can alter the chemical structure and composition of the solidified organic layer in the exposure region. According to the present invention, the solidified organic layer interacts with high-energy electrons. The resulting product, i.e., one or more voxels, remains substantially undamaged and stable even when returned to room temperature conditions, for example. The electron energy may be between 1 keV and 30 keV, for example between 1 keV and 20 keV, for example between 2 keV and 15 keV, for example between 3 keV and 10 keV. Generally, the electron energy can vary between 10 eV and 300 keV. Furthermore, secondary electrons can be generated by inelastic electron-matter interactions. These secondary electrons may have energies of up to approximately 50 eV. Both energies must exceed the several eV required to ionize the outer shell electrons in most of the atoms constituting the solidified organic layer.

[0040] With respect to pore size in digital representations, the pore size may be in the submicrometer range, for example, between 10 nm and 1000 nm, for example between 100 nm and 800 nm, for example between 200 nm and 600 nm.

[0041] As described above, one or more voxels remain substantially undamaged even when exposed to room temperature conditions due to the strong chemical bonds formed between the atoms constituting the solidified organic layer. On the other hand, the unexposed portions of the solidified organic layer sublimate. Room temperature conditions typically refer to uncontrolled atmospheric pressure, room temperature, and normal humidity. These conditions are usually met when the sample is removed from the vacuum chamber, i.e., transported outside the chamber.

[0042] In a second aspect, the present invention relates to a 3D printer for printing digital representations of 3D structures as a stacked arrangement of solidified organic layers.

[0043] This 3D printer is A cryosystem placed inside a high-vacuum chamber, A gas injection system for introducing steam into the high-vacuum chamber in order to continuously form a solidified organic layer, A scanning electron microscope that generates an electron beam, A temperature control system that controls the temperature of the cryosystem and the gas injection system, A 3D ice lithography control system that controls the scanning electron microscope and the temperature control system according to the G code obtained from the digital representation of the 3D structure to be 3D printed, Includes.

[0044] Thus, a second aspect of the present invention relates to a 3D printer for carrying out the method according to the first aspect. For this reason, the configuration of the cryosystem, high vacuum chamber, gas injection system, etc., can be implemented based on the content disclosed in relation to the first aspect.

[0045] The implementation of a temperature control system that controls the temperature of the cryo system and the gas injection system, and a 3D ice lithography control system that controls the scanning electron microscope and the gas injection system according to the G code derived from the digital representation of the 3D structure to be 3D printed, are based on modified commercially available temperature control systems and 3D printer control systems, respectively.

[0046] In a third embodiment, the present invention relates to a method for 3D printing a digital representation of a 3D structure.

[0047] This method is (a) A step of providing a first organic layer on the surface of the substrate, (b) Exposing at least a portion of the first organic layer with at least one electron beam to form one or more voxels within the first organic layer, (c) a step of providing a second organic layer on the surface of the first organic layer, (d) a step of exposing at least a portion of the second organic layer with at least one electron beam to form one or more voxels in the second organic layer, (e) a step of raising the temperature of the first organic layer and the second organic layer in order to evaporate the unexposed areas of the first organic layer and the second organic layer, Includes. In step (b), the one or more voxels are arranged according to a predetermined first pattern. In step (d), the one or more voxels are arranged according to a predetermined second pattern. The predetermined first and second patterns are defined by a first G code and a second G code obtained from a digital representation of the 3D structure to be 3D printed, respectively.

[0048] Thus, a third aspect of the present invention also relates to a method for 3D printing a digital representation of a 3D structure. The present invention is advantageous in that the use of G-code makes it possible to use a very large number of organic layers, for example, hundreds of organic layers. Furthermore, the method according to the third aspect has the advantage of being able to be carried out at room temperature.

[0049] In this embodiment as well, "condensing" should be understood as changing the compound from a fluid phase to a solid phase, similar to the first embodiment.

[0050] Furthermore, in this embodiment of the present invention, G-code should be understood as (x,y) coordinates that define a predetermined pattern in a given z-plane that at least one electron beam should follow. The entire G-code file is generated by slicing the 3D structure to be 3D printed into a stacked arrangement of layers consisting of (x,y) coordinates. Similarly, HPGL or a similar method is treated as G-code.

[0051] The present invention is advantageous in that the use of G-code allows for the use of a very large number of organic layers, for example, several hundred organic layers.

[0052] Therefore, the above method is The process involves forming an additional organic layer by the aforementioned (a) step, The above step (b) involves exposing each of the additional organic layers, The above step (e) involves evaporating the unexposed region of the additional organic layer, It may also include the following.

[0053] In practice, the above method is The process of forming at least 10 additional organic layers, for example, at least 50 additional organic layers, for example, at least 75 additional organic layers, for example, at least 100 additional organic layers, for example, at least 150 additional organic layers, for example, at least 200 additional organic layers, for example, at least 300 additional organic layers, for example, at least 400 additional organic layers, for example, at least 500 additional organic layers, by the process of (a) described above, The above step (b) involves exposing each of the additional organic layers, The above step (e) involves evaporating the unexposed region of the additional organic layer, It may also include the following.

[0054] In general, the solidified organic layer may contain different chemical compositions.

[0055] Therefore, as an example, the first solidified organic layer may have a first chemical composition, the second solidified organic layer may have a second chemical composition, and the first chemical composition and the second chemical composition may be different.

[0056] The one or more voxels may have dimensions between 10 nm and 10,000 nm in the plane of the first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer, for example, dimensions between 10 nm and 1,000 nm, for example, dimensions between 100 nm and 500 nm.

[0057] In this specification, “plane” should be understood as the extent of the solidified organic layer that extends substantially perpendicular to the direction of growth during vapor solidification.

[0058] In a third aspect, the first organic layer, the second organic layer, and / or the additional organic layer are made of wax (C 30 H 62 It may have a layer of )

[0059] Alternatively, or in combination therewith, the first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer may have a renewable chemical, a layer of solidified ethanol, a layer of solidified nonane, and / or a layer of solidified fatty acids derived from vegetable oil.

[0060] Typically, steam can be introduced into a high-vacuum chamber via a gas injection system. This gas injection system may include nozzles designed to control the steam flow rate so that the steam enters the vacuum chamber. Upon contact with the substrate, the steam solidifies to form an organic layer.

[0061] The substrate may have a flat surface or a non-flat surface. Even if the substrate surface is non-flat, the organic layer adheres to the surface due to good adhesion between the substrate surface and the attached vapor. Typically, the substrate may include a wafer. The wafer may be, for example, a standard 100 mm diameter wafer. The wafer material may be silicon or other materials.

[0062] After solidification, the organic layer preferably has a vapor pressure lower than the pressure in the high-vacuum chamber to prevent sublimation. The thickness of the organic layer can be adjusted by both controlling the temperature of the substrate and controlling the amount of vapor introduced into the vacuum chamber.

[0063] The first organic layer, the second organic layer, and / or additional organic layers are wax (C 30 H 62If a layer is included, the substrate temperature during the formation of the organic layer and exposure with at least one electron beam may be about 300K. (e) In step, when the organic layer moves to higher temperature conditions to evaporate the unexposed areas of the organic layer, the substrate may be heated up to about 350K.

[0064] An electron beam is understood to be a stable and well-focused beam of electrons with high current and high energy. The electron beam can alter the chemical structure and composition of the solidified organic layer in the exposure region. According to the present invention, the solidified organic layer interacts with high-energy electrons. The resulting product, i.e., one or more voxels, remains substantially undamaged and stable even when returned to room temperature conditions, for example, room temperature. The electron energy may be between 1 keV and 30 keV, for example between 1 keV and 20 keV, for example between 2 keV and 15 keV, for example between 3 keV and 10 keV. Similarly, the electron energy can generally vary between 10 eV and 300 keV. Furthermore, secondary electrons can be generated by inelastic electron-matter interactions. These secondary electrons may have energies of up to approximately 50 eV. Both energies must exceed the several eV required to ionize the outer shell electrons in most of the atoms constituting the organic layer.

[0065] With respect to pore size in digital representations, the pore size may be in the submicrometer range, for example, between 10 nm and 1000 nm, for example between 100 nm and 800 nm, for example between 200 nm and 600 nm.

[0066] A fourth embodiment relates to a 3D printer for printing digital representations of 3D structures using a stacked arrangement of organic layers.

[0067] This 3D printer is A substrate supporting the stacked arrangement of the aforementioned organic layers, A gas injection system is used to introduce steam in order to continuously form an organic layer. A scanning electron microscope that generates an electron beam, A temperature control system that controls the temperature of the substrate and the gas injection system, A 3D lithography control system that controls the scanning electron microscope and the temperature control system according to the G code obtained from the digital representation of the 3D structure to be 3D printed, Includes.

[0068] Accordingly, a fourth aspect of the present invention relates to a 3D printer for carrying out the method according to the third aspect. For this purpose, possible configurations such as a high vacuum chamber and a gas injection system can be implemented based on what was disclosed in relation to the second aspect.

[0069] The implementation of a temperature control system that controls the substrate temperature and the gas injection system, and a 3D lithography control system that controls a scanning electron microscope and the gas injection system according to G-code derived from a digital representation of a 3D-printed 3D structure, are based on modified versions of commercially available temperature control systems and 3D printer control systems, respectively.

[0070] In general, each aspect of the present invention can be combined and coupled with each other in any way possible within the scope of the invention. These and other aspects, features, and / or advantages of the present invention will become apparent and understandable by referring to the embodiments described below. [Brief explanation of the drawing]

[0071] The present invention will be described in further detail with reference to the accompanying drawings.

[0072] [Figure 1] A diagram showing steps 1 to 6 of 3D printing in a solidified organic layer using an electron beam according to the present invention. [Figure 2]Figures showing electron-coagulation interaction simulations for determining voxel size and their experimental verification. (A): Monte Carlo simulation of electrons injected into nonane CO2 coagulation. 90% of the electron energy is deposited within the garlic-shaped green curve. (B) and (C): AFM images of single-layer cuboids prepared under conditions of 3 keV, 50 nm pitch (B) or 600 nm pitch (C), and area dose of 1–45 mC / cm2. (D): Plot showing the relationship between the thickness of the crosslinked nonane coagulation and the irradiated area dose under conditions of 50–600 nm pitch. (E): Plot showing the relationship between the thickness of the crosslinked nonane coagulation and the exposed area dose using electron energies in the range of 3–10 keV. [Figure 3] Diagram illustrating a 3DIL process model. (A): Coagulated organic material is cross-linked into garlic-shaped voxels, and layers are formed by the overlapping of voxels. (B): Thinner layers are formed by the use of lower doses. (C): A 3DIL model illustrating its unique capabilities, namely (i) freely suspended structures that do not require support structures, (ii) hanging structures, and (iii) closed cavities such as tubes. [Figure 4] A schematic diagram of a nanoscale 3D printing system according to one embodiment of the present invention. (A) shows the configuration diagram of the 3DIL system. (B) shows the configuration diagram of the 3DIL print control program (PCP). (C) shows the electron beam movement, residence time, pitch, and line width. Eleven line segments correspond to eleven G-code instructions. [Figure 5]Figures showing the results of 3DIL. (A): SEM image of a 3D printed test structure with a suspended beam. (B): Inclined cuboid showing layer-by-layer processing. (C): High aspect ratio cuboid and void structure. (D): Tower structure with 500 layers and a height of 28 μm. (E): Distortion-free print result in a 150 × 150 μm² area. Unit cells are automatically positioned and rotated by slicing freeware for optimization of the print area. (F): Freely suspended and fully extended "hanging" wingtip structure without support structure. (G): Evaporation of a microchannel filled with ethanol. (H): 2.5 μm thick layer printed at 10 keV. [Figure 6] Figure showing a wood pile structure using 3DIL. (a): Lattice unit and layer structure in two types of wood pile designs (#1 and #2). (b) and (c): Optical image (left) and SEM image (right) of the wood pile structure before (b) and after (c) thermal annealing. (d): Comparison of reflectance spectra of the wood pile structure. [Figure 7] A diagram showing a 3D structure according to the present invention, prepared using an ethanol solidified material. [Figure 8] This figure shows an inversely designed, axially symmetric, integrated metalens fabricated as a 3D structure according to the present invention. This lens exhibits an numerical aperture (NA) of 0.9, an absolute transmission efficiency (TA) of >0.8, and diffraction-limited focusing characteristics. [Modes for carrying out the invention]

[0073] According to the present invention, a 3D i-lithography (3DIL) process is provided that performs printing in the TPL scale region and bridges the scale gap between FEBID and EBAM.

[0074] The present invention is advantageous in that it facilitates the application of different types of chemical systems associated with temperature. Furthermore, the size of the voxels induced in the organic layer and the thickness of the organic layer can be controlled. Generally, the size of the voxels (body dimensions) can be 10 nm to 10,000 nm, for example, 10 nm to 1,000 nm, or for example, 100 nm to 500 nm. The body dimensions of the voxels extend in the plane of the solidified organic layer, i.e., in a direction perpendicular to the growth direction of the solidified organic layer. The height of the voxels, i.e., the height in the growth direction of the solidified organic layer, preferably matches the thickness of the exposed organic layer. The thickness of the organic layer can be up to a few μm, and the thickness of each organic layer can be controlled with an accuracy of 10 nm.

[0075] Figure 1 shows a six-step 3DIL digital process for printing a "benchy boat" with a length of 54 μm, a height of 38 μm, and 150 layers. The first three steps are common to fused deposition modeling (FDM), but the last three steps are unique to 3DIL. This process required five research challenges and technological innovations: (i) Monte Carlo simulation (MCS) and exposure electron dose testing for electron-solidified material interactions to determine voxel size, (ii) establishment of a 3DIL process model, (iii) application of an affordable and compact scanning electron microscope (SEM) to the 3DIL printer (25), (iv) a communication system for connecting 3DIL printer components, and (v) dedicated firmware for reading G-code from sliced ​​3D CAD drawings and controlling the 3DIL printer. Steps (i), (ii), and (v) are disclosed in detail below, and steps (iii) and (iv) are disclosed briefly.

[0076] Electron-coagulation interaction simulation and voxel size determination 3DIL voxels need to be determined in all 3D printing processes. In this invention, referring to Figure 2, predictive MCS and experimental verification of electron-solidified material interactions are combined. The energy loss (-dE) along the path (ds) of primary electrons (PE) originating from the electron beam in the solidified material is given by Bethe's equation.

[0077]

number

[0078] Based on Bethe's equation, the orbitals of the primary electrons (PE) and their energy losses are visualized by Monte Carlo simulation (MCS) as shown in Figure 2A.

[0079] In the simulation, the electron beam diameter was set to 50 nm, and the energies of the primary irradiated electrons (PE) were set to 3, 5, 7, and 10 keV (see Table 1 below). These energy levels are suitable for a compact thermionic emission SEM.

[0080] In the case of solidified nonane, the interaction volume exhibits a garlic shape. From the 3keV simulation (see Figure 2A), it can be seen that 50% of the initial PE energy is deposited within a cylinder with a height of 150 nm and a diameter of 80 nm, and 95% of the energy is contained within the top 500 nm of the solidified material. Therefore, the simulated 3keV PE voxel has a garlic shape with a body diameter of 500 nm and a height of 500 nm.

[0081] The following very important essential differences should be noted. That is, in the study of electron beam lithography (EBL) and solidified organic resists, it is known that only a very small part of the energy of the electron beam is deposited in the resist or the solidified organic matter, and most of the energy is deposited in the underlying substrate. On the other hand, in 3DIL, all of the primary electron energy is deposited in the solidified organic matter.

[0082] The pitch is changed between 50 nm and 600 nm, and the curing depth at 3 keV is measured (see Figs. 2B and 2C). The dose test is performed using an array of the same square patterns exposed with different area doses, and the thickness of the solidified matter (1 μm) is twice the assumed electron beam penetration depth. In the case of a 50 nm pitch, at a dose less than 3 mC / cm 2 the square is deformed and shifted from the intended position, which will be described later. The thickness of the cross-linked nonane (CLN: cross-linked nonane), that is, the curing depth (Cd), is between 150 nm and 430 nm, and the surface is smooth. At a dose exceeding 10 mC / cm 2 the shape and design of the printed structure match, and the shift in the position of the square is slight. The maximum CLN thickness (d max ) is 430 nm, which is the same as the result of MCS. At a 600 nm pitch, a shape corresponding to the "top of the garlic" and a rougher surface are observed. By the digital process, a missing portion occurs at the left end edge.

[0083] The measurement results of the dose test are used to create the dose curve shown in Fig. 2D. The thickness of the CLN increases with the dose, saturates at 430 nm, and decreases slightly when exceeding 100 mC / cm 2 Therefore, at 3 kV and 10 mC / cm 2When printing, the 3DIL process is very robust because dose fluctuations do not significantly affect the final print. Pitch has only a slight effect on the dose and CLN thickness. In 3DIL, Cd saturates and becomes dose-independent, whereas in the photopolymerization process, Cd increases exponentially with dose due to the amplification effect of polymerization and does not saturate. Therefore, with respect to Cd, 3DIL is more robust than photopolymerization in that small dose fluctuations do not affect print quality. The dose curves for PE electrons at 3, 5, 7, and 10 keV are shown in Figure 2E. At 3 keV and 5 keV, the plots and simulation results agreed well. At 7 keV and 10 keV, the CLN thickness saturated at 1400 nm and 2500 nm, respectively. Each plot shows one abrupt change, which is due to bleeding in low-dose prints.

[0084] Therefore, by adjusting the MCS and electron energy, it is possible to predict and select the voxel size. For example, 3 keV and 10 mC / cm. 2 When nonane is exposed using this method, the vertical voxel size is 430 nm and the lateral size is 450 nm (see Figure 2A). When processing solidified nonane using a small SEM, a voxel size of 500 to 2500 nm can be selected by changing the electron energy in the range of 3 to 10 keV. A wider voxel size range is expected to be obtained with advanced SEMs. Compared to TPL, TPL voxels are ellipsoidal in shape, with a minimum vertical size of 1000 nm and a minimum lateral size of 300 nm. The voxel size of 3DIL can be increased by changing the exposure conditions.

[0085] Table 1.3 shows the print parameters for electron energies of 10 keV. The critical area dose (CDA) is the maximum thickness d at a given electron beam energy. maxThis is the area dose required to bridge a solidified material with a thickness equivalent to 80% of the critical thickness (i.e., dc). The critical volume dose (CDV) is 2CDA / d max It is defined as follows. [Table 2]

[0086] 3D ice lithography process model (ii): Based on Monte Carlo simulations (MCS) of electron-solidified material interactions and their experimental verification, a 3DIL process model is presented with reference to Figure 3. High dose (3 keV, 10 mC / cm²) 2 When exposed to a low dose (5 mC / cm²), the voxel corresponds to the entire electron-coagulation interaction volume, exhibiting a garlic shape. 2 When exposed to ) (see Figure 3B), the interaction volume itself is the same, but only the central part reaches the CDA required for crosslinking, resulting in the formation of a thinner crosslinked nonane (CLN) layer. Because the CLN layer is not fixed to the substrate, its position may be slightly shifted. This phenomenon has been observed in dose tests (see Figure 2B). A small pitch results in a smooth surface. Approximately half the thickness of the CLN (250 nm) is set as d, and each layer receives approximately twice the cumulative applied dose.

[0087] Another approach is to print using CDA and dc. For example, at 3keV, 5mC / cm 2 Using this method, set d to 200 nm. In this case, the total dose for each layer is 5 mC / cm 2Slightly exceeding this, the printing speed improves by approximately four times. However, the reproducibility of the print may be compromised because the shape becomes very sensitive to dose fluctuations. Interestingly, the critical volume dose (CDV) at 10 keV is twice that at 3 keV (see Table 1). Therefore, it appears that the fastest prints are made at the lowest primary electron (PE) energy, but since many SEMs provide larger electron beam currents at higher PE energies, the fastest prints are actually achieved at the highest PE energy.

[0088] In addition to 3DIL's ability to handle chemical systems other than photopolymers, this process model demonstrates that 3DIL complements TPL in three ways. Firstly, because the gas-liquid interface is avoided, fragile suspended structures can be printed without the microstructure being destroyed by strong capillary forces. Secondly, 3DIL enables "hanging" structures, which is not possible with TPL because unfixed structures move freely in the liquid. Thirdly, because uncrosslinked organic molecules sublimate easily from narrow, partially closed structures, it is possible to fabricate tubular and capillary structures.

[0089] In TPL, the fabrication of tube structures is extremely difficult because it is challenging to remove the high-viscosity liquid photopolymer from the inside of high-aspect-ratio tubes. Furthermore, because TPL uses highly viscous liquid photopolymer resins, post-processing such as critical point drying and meticulous care are required when drying delicate devices. These advantages will be demonstrated in the examples described later.

[0090] Firmware for 3DIL process control (iii) The 3DIL printer is based on a small scanning electron microscope (SEM) to provide the necessary electron beam and vacuum chamber (see Figure 4A). A cryostage is installed inside the SEM to cool the process substrate to 80K. The precursor gas is controlled via a special automated gas injection system (GIS) module connected to a nozzle inside the SEM.

[0091] (iv) The SEM, GIS, and stage temperature control system are connected to the 3DIL control system (CS). The CS controls the scanning coil of the SEM and acquires input from the electron detector, enabling SEM image acquisition and electron beam position control. Furthermore, the CS reads and controls the GIS, enabling automatic injection of the precursor and control of the solidified layer thickness.

[0092] (v): CS is controlled by a 3DIL print control program (PCP), which automates the gas injection and electron beam exposure sequences in 3DIL (see Figure 4B). The PCP is compatible with most industrial 3D printing and AM digital manufacturing and can leverage advanced AM digital software toolboxes and 3DCAD databases. Therefore, the PCP is fundamentally different from electron beam lithography which uses electronic design automation data formats (e.g., GDSII, CIF, and GERBER) or FEBID which uses proprietary software that requires electron-gas-surface interaction simulations for each voxel. In 3DIL printing, the user must first calibrate the GIS and precursor solidification thickness. After initial calibration, the user uses a G-code file and area exposure dose (Q a ), electron beam current (I e Five inputs are provided: (a), pitch size (p), and layer thickness (d).

[0093] G-code files are generated by slicing 3D CAD files using freeware (e.g., Ultimaker CURA). The user needs to input d and line width lw. In this study, p = lw. Q a , p, and I e This is used to calculate the residence time (Δtd) and writing time of the electron beam.

[0094] The PCP reads the G-code and extracts the commands necessary to print each layer. Each line of G-code instruction includes an operation code and target coordinates, which the PCP uses to guide the electron beam to the specified position and bridge the solidified material. The PCP consists of two loops. The "layer loop" prints one layer and begins with injection control to activate the GIS and solidify the solidified layer on the sample. Subsequently, the "command loop" is executed, iterating through each line of G-code instruction within the layer and extracting all target coordinates. For each G-code target coordinate, the PCP generates an exposure path consisting of exposure points corresponding to voxels.

[0095] All voxel coordinates within a single layer are encoded as an (x,y) coordinate array (see Figure 4C). The length and pitch p of the G-code vector determine the size of this array. The (x,y) array is then converted into a (U,V) voltage array. Thus, each layer generates an array of (U,V) signals. These voltage signals and Δtd control the scanning coil of the SEM via CS, enabling precise positioning, dwell, and crosslinking of the solidified material with high accuracy.

[0096] As mentioned above, HPGL (and similar methods) are vector-based graphic tools suitable for controlling printers, plotters, other output devices, and even electron beams, and are therefore treated as G-code.

[0097] 3D printing results After establishing the 3DIL model, printer, control system, and software, a 3D test structure was printed under the conditions of 3keV, d=250nm, p=50nm, and a total of 43 layers (see Figure 5A). High-magnification images (see Figure 5B) show that a maximum tilt angle of 45° was observed, and that an end-supported horizontal beam with a width of 1.5μm, a thickness of 2μm, and a length of 7μm was successfully printed.

[0098] Figure 5C shows a high aspect ratio cuboid with a width of 1.1 μm and a height of 11 μm. Cuboids with a width greater than 1.5 μm showed good integrity, but thinner cuboids leaned on other structures or collapsed. When the design width was 1.5 μm, the actual printed structure width was 1.7 μm, and the voids between structures were 1.1 μm. These errors are attributed to the electron-solidification interaction volume and digital slicing. The surface quality of the first three layers is very smooth (see Figure 2B), but a small number of hemispherical protrusions are also observed, as shown in Figure 5B. These are likely microbubbles resulting from impurities from the vacuum chamber, impurities in the nonane, or gases generated during the crosslinking process.

[0099] Gases are generated during the photopolymerization process, and gas diffusion is necessary to avoid bubble formation. While bubble accumulation results in a rough surface, this can potentially be improved by an optimized printing process that allows for controlled gas diffusion. Furthermore, using organic molecules that generate less gas during crosslinking can also help avoid bubbles.

[0100] Interlayer misalignment is occasionally observed (see Figure 5B). This misalignment has been measured at less than 200 nm and is attributed to cryostage drift. By leveraging the imaging capabilities of the SEM, it may be possible to compensate for this drift through automated image processing and alignment algorithms. Since the depth of focus of the SEM is approximately 10 μm, blurring due to electron beam defocusing is expected for structures exceeding 10 μm in height. To verify this, an Eiffel Tower structure with a height of 28 μm and a minimum structural width of 550 nm was printed (see Figure 5D). As expected, the first 10 μm was printed with good quality, but blurring occurred in the remaining 20 μm, the tower tilted slightly, and thin beams fused. Therefore, focus correction is necessary when printing tall structures or fine features.

[0101] Figure 5E shows a 150 × 150 μm unit cell consisting of nine units for evaluating strain. 2 The print results are shown, and no distortion is observed. The 3DIL model and 3D printing tests demonstrate that it is possible to print fragile, suspended "hanging" structures. As proof, a dragon structure with wings 16 μm away from the main body and a thickness of 900 nm was printed (see Figure 5F). In TPL, due to the destructive interfacial forces during drying, a support is required for fine structures, making such suspended structures difficult.

[0102] The wingtips have a "hanging" structure, which is impossible with photopolymer 3D printing. Furthermore, to demonstrate that 3DIL can print hollow structures, we printed microchannels with important applications such as in-situ diagnostics and organ-on-a-chip. Mimicking vascular capillaries, we printed microchannels with inner diameters between 3.5 μm and 6.4 μm and filled them with ethanol (see Figure 5G). As the ethanol began to evaporate from the free openings, the gas-liquid interface moved towards the center of the channel, and eventually all the ethanol dried out.

[0103] Furthermore, to demonstrate the flexibility in selecting and adjusting voxel size, 3D structures were printed under conditions of 10 keV and a layer thickness of 2.5 μm (see Figure 5H). Finally, to show that the 3DIL process is suitable for metal-organic chemistry, printing was also performed using gold-containing organic compounds.

[0104] Based on the above, the present invention provides the first AM electronic process for solidified organic materials, which applies a digital manufacturing paradigm and integrates physical modeling, 3D CAD modeling, slicing, and layer-by-layer printing.

[0105] To demonstrate size-dependent nanophotonic effects, we printed stacked wood structures, commonly used in photonic crystals (PhCs) and mechanical metamaterials. These stacked structures are typically fabricated using two-photon lithography (TPL) or complex iterative lithography and plasma etching. This study aimed to demonstrate lattice size-dependent scattering differences in the UV region.

[0106] The lattice unit sizes in designs #1 and #2 were 1.5 μm and 2.5 μm, respectively (see Figure 6A). Design #2 was expected to exhibit different effects than design #1. Using 3DIL and diesel as a precursor, two stacked structures consisting of 70 layers were printed (see Figures 6B and 6C). The thickness of each layer was 200 nm. The stacked structures were annealed at 300°C for 10 minutes in an argon atmosphere (1 bar) to reduce the lattice size. As expected, after annealing, the color of the stacked structures changed from white to a reddish color (see Figure 6C). SEM analysis (right panel of Figures 6B and 6C) showed that the lateral shrinkage was 31% for design #1 and 33% for design #2, and the longitudinal shrinkage was 42%.

[0107] The reflectance spectrum was measured using a micro-spectrophotometer (see Figure 6D). Immediately after printing, the structure exhibits uniform reflection in the visible light region and is observed as "white." Interference fringes are due to thin-film interference. After annealing, the lattice size decreases, and the reflectance in the UV region decreases (absorption increases), resulting in an observed "reddish" color. In design #2 with a larger unit size, absorption in the UV region is small, and the spectrum shifts slightly towards shorter wavelengths. This size-dependent structural color is based on a different mechanism than that of 3D photonic crystals.

[0108] The inventors performed 3DIL using nonane as the starting material and printed 3D structures up to 150 μm wide and 28 μm high. Layer thicknesses ranged from 250 nm to 2.5 μm, with the narrowest line width being 550 nm. 3DIL bridges the scale gap between FEBID and EBAM, both of which are electron beam 3D printing methods. With minor modifications, 3DIL equipment can be made compatible with FEBID, and by combining FEBID and 3DIL, 3D structures in the range of 1 nm to 100 μm can be printed. Furthermore, 3DIL can be scaled up using higher-power EBAM equipment (16).

[0109] Because 3DIL is based on a crosslinking process rather than polymerization, its throughput is inherently lower than stereolithography, TPL, and other photopolymerization AM processes. However, 3DIL is extremely useful as a complementary technology to photon polymerization processes and has potential for chemical reactions in other organic chemistry fields such as metal-organic chemistry, organic semiconductor chemistry, and medicinal chemistry, as well as for 3D printing using these reactions.

[0110] Furthermore, the inventors printed 3D structures using ethanol, a renewable chemical substance, based on the present invention (see Figure 7). When high-energy electrons in the range of 3-20 keV interact with solidified ethanol, radicals are generated, which react with other ethanol molecules to form crosslinked molecules that become solid at room temperature. The electron energy required to crosslink ethanol is approximately 10 times that required for nonanes. It is thought that approximately 10 times more crosslinking is necessary for ethanol, which has a smaller molecular size, to exist stably at room temperature. Compared to nonanes, the crosslinked ethanol structures were highly porous. This is likely due to gases and volatile ethanol fragments generated during the crosslinking process. The pore size is submicrometer, for example, in the range between 10 nm and 1000 nm, for example between 100 nm and 800 nm, for example between 200 nm and 600 nm. These structures can be used as biofilters in lab-on-a-chip and organ-on-a-chip applications.

[0111] Figure 7a shows the chemical reaction that occurs when electrons interact with solidified ethanol during production according to the present invention. High-energy electrons cause bond cleavage, generating hydrocarbon radicals. These radicals can recombine, react with other molecules (crosslinking) to form a solid network, or generate volatile gases. In solidified ethanol, solidification, crosslinking, and volatile gas generation proceed simultaneously. Figure 7b shows an SEM image of a "benchy boat" made of crosslinked solidified ethanol with numerous pores.

[0112] Furthermore, Figure 8 shows an integrated axially symmetric metalens that can be manufactured according to the present invention. Numerical evaluations show that this metalens exhibits high transmittance (T>0.8), diffraction-limited focusing, and high numerical aperture (NA≒0.9). Fabricating this metasurface as a 3D-generated structure is a significant advance for the field of flat optics. The integrated axially symmetric metalens reproduced here has a thickness of 9 μm and a diameter of 140 μm, and can be composed of 180 layers of solidified organic material with a thickness of 50 nm. Different chemical substances have different dielectric properties, and consequently different refractive indices; therefore, it is possible to adjust the refractive index by selecting the appropriate chemical substance. For example, cross-linked nonanes are similar to poly(ethylene), and cross-linked aromatic compounds exhibit properties similar to poly(styrene).

[0113] The inventors believe that this invention makes it possible to reduce the voxel size, for example, from 500 nm to 100 nm. If a voxel size of around 100 nm is achieved, it may be possible to sustainably manufacture photonic crystals in the visible wavelength range and completely avoid energy-intensive high-temperature post-processing.

[0114] Furthermore, this invention has the potential to have a significant impact on the prototyping and manufacturing of MEMS devices by reducing the barriers to entry for small-scale, economical, and sustainable production. The invention also has the potential to pave the way for the realization of medium-scale production machines by integrating and adapting multi-electron beam lithography with 250,000 beams, which is used in the production of EUV lithography masks. Overall, the inventors believe this invention has the potential to become a sustainable manufacturing process in small- and medium-scale MEMS sensor production.

[0115] The inventors believe that further research is needed to investigate which renewable chemical systems could serve as suitable vapor precursors, potentially providing long-term durable and stable 3D structures. The results for solidified ethanol shown in Figure 7 are promising. Furthermore, research has been proposed to print non-porous structures, which can be achieved by using larger molecules in the vapor, such as fatty acids derived from plant-based edible oils. However, unlike ethanol, these biochemicals have very low vapor pressures at room temperature, so heating is required to increase the vapor pressure when using fatty acids as precursors. Even when heating is required, the temperature should not exceed the boiling point of approximately 200°C, and the vapor pressure should preferably not exceed 100 mbar.

[0116] Currently available GIS (Geographic Insulation System) tends to accommodate only one type of material, making it difficult to add other chemicals at present. Therefore, the inventors propose to provide a GIS that can internally mix two or more chemicals.

[0117] To enable the use of fatty acids in 3DIL, a redesign of the GIS (Geographic Information System) is desired to allow the material to be heated up to 100°C.

[0118] Furthermore, advanced control and software development are required. For example, for printing with multiple materials, the GIS needs to control different gases. Also, the GIS must mix the gases to obtain the desired stoichiometric ratio required for direct electron injection chemical reactions.

[0119] The inventors plan to optimize the process to improve the device and achieve KPIs. Process parameters include electron energy, solidification thickness, dose, and electron beam current.

[0120] Although the present invention has been described above with reference to examples, the present invention is not limited to these specific examples, and various modifications are possible without departing from the spirit of the invention. Therefore, the aforementioned examples are not intended to strictly limit the appended claims to them. Rather, these examples are intended solely to illustrate the language of the claims and are not intended to limit the claims to these examples. The scope of protection of the present invention should be interpreted based on the appended claims alone, and if there is any ambiguity in the language of the claims, these examples should be used for interpretation.

Claims

1. A method for 3D printing a digital representation of a 3D structure, (a) A step in which vapor is solidified on the surface of the cooled substrate to form a first solidified organic layer, (b) A step of exposing at least a portion of the first solidified organic layer with at least one electron beam to form one or more voxels within the first solidified organic layer, (c) A step in which vapor is solidified on the surface of the first solidified organic layer to form a second solidified organic layer, (d) A step of exposing at least a portion of the second solidified organic layer with at least one electron beam to form one or more voxels in the second solidified organic layer, (e) A step of transferring the first solidified organic layer and the second solidified organic layer to ambient conditions in order to evaporate the unexposed areas of the first solidified organic layer and the second solidified organic layer, Includes, In step (b) above, the one or more voxels are arranged according to a predetermined first pattern and remain substantially undamaged under ambient conditions. In step (d) above, the one or more voxels are arranged according to a predetermined second pattern and remain substantially undamaged under ambient conditions. The predetermined first and second patterns are defined by a first G-code and a second G-code obtained from a digital representation of a 3D structure to be 3D printed, respectively. method.

2. The above step (a) is a step of forming an additional solidified organic layer, The above step (b) involves exposing each of the additional solidified organic layers, The above step (e) involves evaporating the unexposed region of the additional solidified organic layer, This also includes, The method according to claim 1.

3. The process of forming at least 10 additional solidified organic layers, for example, at least 50 additional solidified organic layers, for example, at least 75 additional solidified organic layers, for example, at least 100 additional solidified organic layers, for example, at least 150 additional solidified organic layers, for example, at least 200 additional solidified organic layers, for example, at least 300 additional solidified organic layers, for example, at least 400 additional solidified organic layers, for example, at least 500 additional solidified organic layers, by the process of (a) described above, The above step (b) involves exposing each of the additional solidified organic layers, The above step (e) involves evaporating the unexposed region of the additional solidified organic layer, This also includes, The method according to claim 2.

4. The method according to claim 3, wherein the one or more voxels have dimensions between 10 nm and 10,000 nm, for example between 10 nm and 1,000 nm, or for example between 100 nm and 500 nm, in the plane of the first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer.

5. The first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer are solidified diesel (C ９ H ２０ The method according to claim 3 or 4, having a layer of ).

6. The method according to claim 3 or 4, wherein the first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer comprises a renewable chemical substance.

7. The method according to claim 3 or 4, wherein the first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer have layers of solidified ethanol.

8. The method according to claim 3 or 4, wherein the first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer have layers of solidified nonane.

9. The first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer each include a layer of solidified fatty acids. The aforementioned fatty acids are derived from vegetable oils. The method according to claim 3 or 4.

10. The first solidified organic layer has a first chemical composition, The second solidified organic layer has a second chemical composition, The first chemical composition and the second chemical composition are different. The method according to any one of claims 1 to 9.

11. The method according to any one of claims 1 to 10, wherein the energy of the at least one electron beam is in the range between 2 keV and 15 keV, for example, in the range between 3 keV and 10 keV.

12. The method according to any one of claims 1 to 11, wherein the pore size in the digital representation is in the submicrometer range, for example, between 50 nm and 1000 nm, for example between 100 nm and 800 nm, for example between 200 nm and 600 nm.

13. The method according to any one of claims 1 to 12, wherein the temperature of the cooled substrate is less than 200K, for example less than 170K, for example less than 150K, for example less than 130K, for example less than 110K, for example less than 90K, for example about 80K.

14. The method according to any one of claims 1 to 13, wherein the cooled substrate is placed in a cryosystem located in a high vacuum chamber.

15. The method according to claim 14, wherein the steam is introduced into the high vacuum chamber via a gas injection system.

16. A 3D printer for printing digital representations of 3D structures using a layered arrangement of solidified organic material, A cryosystem placed inside a high-vacuum chamber, A gas injection system for introducing steam into the high-vacuum chamber in order to continuously form a solidified organic layer, A scanning electron microscope that generates an electron beam, A temperature control system that controls the temperature of the cryosystem and the gas injection system, A 3D ice lithography control system controls the scanning electron microscope and the temperature control system according to the G code obtained from the digital representation of the 3D structure that is 3D printed, including, 3D printer.

17. A method for 3D printing a digital representation of a 3D structure, (a) A step of providing a first organic layer on the surface of the substrate, (b) Exposing at least a portion of the first organic layer with at least one electron beam to form one or more voxels within the first organic layer, (c) a step of providing a second organic layer on the surface of the first organic layer, (d) A step of exposing at least a portion of the second organic layer with at least one electron beam to form one or more voxels in the second organic layer, (e) A step of raising the temperature of the first organic layer and the second organic layer in order to evaporate the unexposed areas of the first organic layer and the second organic layer, Includes, In step (b) above, the one or more voxels are arranged according to a predetermined first pattern, In step (d) above, the one or more voxels are arranged according to a predetermined second pattern, The predetermined first and second patterns are defined by a first G-code and a second G-code obtained from a digital representation of a 3D structure to be 3D printed, respectively. method.

18. The process involves forming an additional organic layer by the above (a) step, The above step (b) involves exposing each of the additional organic layers, The above step (e) involves evaporating the unexposed region of the additional organic layer, This also includes, The method according to claim 17.

19. The process of forming at least 10 additional organic layers, for example, at least 50 additional organic layers, for example, at least 75 additional organic layers, for example, at least 100 additional organic layers, for example, at least 150 additional organic layers, for example, at least 200 additional organic layers, for example, at least 300 additional organic layers, for example, at least 400 additional organic layers, for example, at least 500 additional organic layers, by the process of (a) described above, The above step (b) involves exposing each of the additional organic layers, The above step (e) involves evaporating the unexposed region of the additional organic layer, This also includes, The method according to claim 18.

20. The method according to claim 20, wherein the one or more voxels have dimensions between 10 nm and 10,000 nm, for example between 10 nm and 1,000 nm, or for example between 100 nm and 500 nm, in the plane of the first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer.

21. The first organic layer, the second organic layer, and / or the additional organic layer are made of wax (C ３０ H ６２ The method according to claim 19 or 20, having a layer of ).

22. The method according to claim 19 or 20, wherein the first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer comprises a renewable chemical substance.

23. The method according to claim 19 or 20, wherein the first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer have layers of solidified ethanol.

24. The method according to claim 19 or 20, wherein the first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer have layers of solidified nonane.

25. The first solidified organic layer, the second solidified organic layer, and / or the additional solidified organic layer each include a layer of solidified fatty acids. The aforementioned fatty acids are derived from vegetable oils. The method according to claim 19 or 20.

26. The first solidified organic layer has a first chemical composition, The second solidified organic layer has a second chemical composition, The first chemical composition and the second chemical composition are different. The method according to any one of claims 17 to 25.

27. The method according to any one of claims 17 to 26, wherein the energy of the at least one electron beam is in the range between 2 keV and 15 keV, for example, in the range between 3 keV and 10 keV.

28. The method according to any one of claims 17 to 27, wherein the pore size in the digital representation is in the submicrometer range, for example, between 50 nm and 1000 nm, for example between 100 nm and 800 nm, or for example between 200 nm and 600 nm.

29. The method according to any one of claims 17 to 29, wherein the temperature of the cooled substrate is less than 200K, for example less than 170K, for example less than 150K, for example less than 130K, for example less than 110K, for example less than 90K, for example about 80K.

30. The method according to any one of claims 17 to 30, wherein the cooled substrate is placed in a cryosystem located in a high vacuum chamber.

31. The method according to claim 14, wherein the steam is introduced into the high vacuum chamber via a gas injection system.

32. A 3D printer for printing digital representations of 3D structures using a layered arrangement of organic materials, A substrate supporting the stacked arrangement of the aforementioned organic layers, A gas injection system is used to introduce steam in order to continuously form an organic layer. A scanning electron microscope that generates an electron beam, A temperature control system that controls the temperature of the substrate and the gas injection system, A 3D lithography control system that controls the scanning electron microscope and the temperature control system according to the G code obtained from the digital representation of the 3D structure to be 3D printed, including, 3D printer.

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