Method for manufacturing three-dimensional nanostructures with large aspect ratios

Abstract

The present invention relates to a method for producing a three-dimensional nanostructure, the method comprising the steps of: - oscillating an injector (100) between a low position in contact with the substrate (20) and a high position out of contact with the substrate (20), the injector (100) having a discharge orifice (108) with a diameter larger than 0.1; - depositing ink onto the substrate (20) by the injector (100), while the outlet orifice (108) of the injector (100) is in contact with the substrate (20), the ink comprising a volume % of the total volume of the ink; - less than 15% nanoparticles selected from metal nanoparticles, metal oxide nanoparticles, graphene oxide nanoparticles, or a combination thereof; - 0.5% to 5% dispersant, - at least 80% of a solvent in which the metal nanoparticles can be dispersed to form the infused ink and which is sufficiently volatile to allow solidification of the ink once it is deposited; and - Withdrawing the injector (100) from the substrate (20) in a direction substantially perpendicular to the substrate at a rate of 10 while maintaining a flow of ink from the injector. The invention also relates to the nanostructures obtained by this method.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to the fabrication of three-dimensional nanostructures, in particular nanostructures with a large aspect ratio greater than 1, such as nanostructure pillars, which may in particular have the shape of a cylinder with a substantially constant upward diameter or a rounded conical pin with an upward decreasing diameter. The three-dimensional nanostructures can be used in the fields of microelectronics, optoelectronics, energy conversion, and the fabrication of nanodevices and nanosensors, in particular for integration into screens, processors (especially quantum processors), and in vitro diagnostic devices.

[0002] Various techniques exist for fabricating three-dimensional nanostructures with aspect ratios greater than one. The aspect ratio of a structure is understood here as the ratio of two dimensions of this structure. In particular, if the structure extends in the direction of extension and forms, for example, a pillar or a pin, the aspect ratio is the ratio of the length of the structure in the direction of extension to the width of the structure in a direction transverse or perpendicular to this direction of extension. The larger the aspect ratio, the more elongated the structure appears in the direction of extension, and in the case of a pillar, the smaller the diameter relative to its height.

[0003] Three-dimensional nanostructures with aspect ratios greater than 10:1 can be fabricated by direct 3D printing using fast-drying silver Newtonian ink (see Lee et al. ACS Appl. Mater. Interfaces 2017, 9, 22, 18918-18924 for a review of this topic). However, this technique results in structures with very rough surfaces.

[0004] There are also techniques based on the polymerization of photosensitive solutions. These techniques require the use of a mixture of a metal colloid suspension and a photosensitive monomer (a monomer that polymerizes during production). However, the resulting structures are porous and have poor electrical conductivity. These techniques can also be used to fabricate molds for nanoimprint lithography (NIL). Therefore, one mold is needed for each size and arrangement of nanostructures, making the manufacturing process more expensive.

[0005] Other techniques exist, such as electrodeposition and the redox electrohydrodynamic technique described by Reiser et al. (Nature Communications, vol. 10, 1, 2019), which relies on applying an electric field between a conductive substrate and a conductive suspension. These require the use of conductive inks and supports, particularly due to the limitations of zinc plating. The production speed is slow, limited by the kinetics of the chemical reactions occurring at the tip of the capillary or AFM used. Furthermore, electrohydrodynamic techniques require drop-by-drop (and therefore discontinuous) deposition, generating satellite droplets that create undesirable surface irregularities.

[0006] Finally, there are techniques based on application by direct printing, where the deposition of the metal ink is monitored by a camera. Therefore, there is a need for a method for manufacturing three-dimensional nanostructures with improved surface conditions that can shorten and simplify manufacturing time by eliminating the need for a system that monitors film formation with a camera. Summary of the Invention

[0007] The object of the present invention is to propose a method for producing three-dimensional nanostructures, in particular nanostructures with an aspect ratio greater than 1, which makes it possible to produce nanostructures with surfaces that can be smoothed or layered at a faster rate than in the prior art.

[0008] The above object is achieved in the context of the present invention by a method for producing a polymerizable compound according to the claims, in other words a method comprising the following steps: - oscillating an injector (100) between a low position in contact with the substrate (20) and a high position out of contact with the substrate (20), the injector (100) having an outlet orifice (108) with a diameter greater than 0.1 μm; - depositing ink onto the substrate (20) by the injector (100) while the outlet orifice (108) of the injector (100) is in contact with the substrate (20), the ink comprising, in volume % relative to the total volume of the ink: less than 15% nanoparticles selected from metal nanoparticles, metal oxide nanoparticles, graphene oxide nanoparticles, quantum dots, or combinations thereof; -0.5% to 5% dispersant, At least 80% solvent in which the metal nanoparticles can be dispersed to form the ink to be infused and which has sufficient volatility to allow the ink to solidify once deposited a process comprising: - Removing the injector (100) from the substrate (20) in a direction substantially perpendicular to the substrate at a speed of 10 μm / s or less while maintaining the flow of ink from the injector.

[0009] The expression "substantially perpendicular" means that the direction forms an angle of 90°±10° with the base substrate.

[0010] The method step, which consists of withdrawing the injector from the substrate in a direction non-parallel to the substrate while maintaining the flow of ink from the injector, makes it possible to produce nanostructured pillars with an aspect ratio greater than 1, e.g., pillars 1 μm in diameter and 30 m in length. These pillars also have an advantageously low surface roughness. Furthermore, the method can produce pillars as fast as a few seconds per pillar and can be performed on any substrate without zinc plating limitations.

[0011] Such a method is advantageously further characterized by the following various features, taken alone or in combination:

[0012] the ink comprises 0.05% to 15% by volume, advantageously 0.2% to 10% by volume, more advantageously 4% to 8% by volume of nanoparticles relative to the total volume of the ink;

[0013] The diameter of the discharge orifice (108) is between 0.1 μm and 50 μm, advantageously between 0.5 μm and 30 μm.

[0014] The volatile solvent is selected from the group consisting of water, alcohols, glycols, glycol ethers, and mixtures thereof. The ink contains 80% to 99.45% by volume of the solvent relative to the total volume of the ink.

[0015] The volatile solvent further comprises a second solvent, said second solvent being glycerol, advantageously in a content such that the ink comprises between 0% and 25% by volume of glycerol relative to the total volume of the ink.

[0016] The metal of the metal nanoparticles is selected from silver, copper, gold, platinum, nickel, aluminum, cobalt, combinations thereof, or alloys thereof.

[0017] - the metal oxide of the metal oxide nanoparticles is selected from ZnO, TiO2 or V2O5; The ink further comprises a dispersant, advantageously chosen from polyvinylpyrrolidone (PVP), gum arabic, polyvinyl alcohol (PVA), polyacrylic acid (PAA) polyallylamine (PAAm), polysodium styrenesulfonate (PSS), 3-(aminopropyl)trimethylsilane (APS), fatty acids, cetyltrimethylammonium bromide (CTAB), tetraoctylammonium bromide (TOAB), sodium citrate, laurylamine, dodecanethiol, mercaptopolyethylene glycol, mercaptopolypropylene glycol, or combinations thereof.

[0018] During the step of separating the injector from the substrate, the injector is separated at a speed ranging from 1 μm / s to 10 μm / s; The method includes a step of disrupting the gap between the three-dimensional nanostructures formed and the ink deposited by withdrawing the injector (100) from the substrate (20), advantageously at a speed greater than 10 μm / s.

[0019] the method comprising the steps of: - moving the injector relative to the substrate (20) in a direction (x, y) parallel to the substrate; - carrying out the steps described above, and The method further comprises performing the cycle of at least one of the steps.

[0020] - the method includes a step of curing the substrate containing the formed nanostructures; The invention also relates to a product comprising a three-dimensional nanostructure obtained by the method as described above. Such products are advantageously further characterized in that the nanostructures have a length at least 10 times greater than the width of the nanostructures. In another alternative, such products are advantageously further characterized in that the nanostructures have diameters that decrease in height.

[0021] Other features and advantages of the present invention will become apparent from the following description, which is given purely by way of example and should not be construed as limiting. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic diagram of pillar formation. [Figure 2] 1 is a schematic diagram of a system for fabricating three-dimensional nanostructures according to one embodiment of the present invention. [Figure 3] 4 shows a photograph of the shape of the pillars obtained with the method according to the invention. [Figure 4]Photographs of the pillar shapes obtained in Test 3 (4A), Test 4 (4B), or the flattened dome from Test 8 (4C). [Figure 5] 10 is a photograph showing the results of carrying out Comparative Example 1. [Figure 6] Photographs of the pillar shapes obtained in Example 6 (6A: D=5, 6B: D=10 μm); [Figure 7] Photograph of the pillar obtained in Test 33. [Figure 8] 2 shows two photographs of the results of carrying out Comparative Example 2. NP concentration (volume %) [Figure 9] Figure 3 shows a photograph of the pillar obtained in test 35. Pull-off speed (μms-1) [Figure 10] FIG. 10A is a graphical representation reporting the maximum pipette pull-off velocity V (μm / s) as a function of the diameter of the pipette used when the volume concentration of metal particles in the ink is 5.8%, and FIG. 10B is a graphical representation reporting the maximum pipette pull-off velocity V (μm / s) for a pipette with a diameter of 5±1 μm as a function of the volume concentration of metal particles in the ink. [Figure 11] Photograph of the pillar obtained in Test 37. [Figure 12] 1 is a photograph of the pillars obtained in Example 9. Specific Description of the Invention

[0023] A system for the controlled deposition of ink on any substrate has already been described in application WO 2020 / 128310. The system described therein allows the deposition of ink with defined features with lengths of 1 μm or more. The system consists of a mechanical resonator attached to an injector. Under these conditions, it has now been discovered that it is possible to deposit ink and stretch it in an elongation direction to form nanostructures such as pillars or pins.

[0024] To do this, the method described in application WO2020 / 128310 consists of withdrawing the injector from the substrate in a direction not parallel to the substrate, in particular in a direction substantially perpendicular to the substrate, at a speed of less than or equal to 10 μm / s, and the ink to be deposited consists of metal nanoparticles and / or metal oxide nanoparticles and / or graphene oxide particles and a sufficiently volatile solvent.

[0025] In the present invention, the term "stretching" means that the deposition is continuous, as opposed to, for example, drop-by-drop deposition.

[0026] The three-dimensional nanostructures are formed by evaporation of the solvent contained in the ink at the exit of the ejection orifice, as shown in Figure 1. - the substrate and the injector outlet come into contact. Upon contact, a liquid meniscus of the ink contained in the injector appears between the outlet of the outlet orifice and the substrate (1A); -We believe that when the injector outlet orifice and the substrate are pulled away from each other at a speed of 10 μm / s or less, the solvent evaporates, inducing a concentration and / or local accumulation of nanoparticles at the liquid-gas interface of the meniscus, forming a solid phase consisting of dense agglomerates of nanoparticles (1B and 1C); -To move the injector nozzle away from the formed three-dimensional nanostructure (1D), the injector nozzle and the substrate are pulled away from each other at a speed of 10 μm / s or more.

[0027] The ink used consists of metal nanoparticles, metal oxide nanoparticles, graphene nanoparticles, or optionally quantum dots (hereinafter also referred to as nanoparticles), and a volatile solvent.

[0028] Advantageously, the ink comprises 0.05% to 15% by volume of nanoparticles relative to the total volume of the ink, advantageously 0.2% to 10% by volume, more advantageously 4% to 8% by volume.

[0029] The nanoparticles advantageously have an average particle size D50 ranging from 1 nm to 300 nm, advantageously from 30 nm to 200 nm. The particle size can be determined by high resolution scanning electron microscopy (HRSEM) or light transmission analysis (Lumisizer (商標) etc.) can be determined by the device.

[0030] The nanoparticles are preferably conductive or semiconductive nanoparticles. They are preferably metal nanoparticles, the metal of which is selected from silver, copper, gold, platinum, nickel, aluminum, cobalt, zinc, indium, palladium, combinations thereof or alloys thereof. In particular, the nanoparticles are metal nanoparticles, the metal of which is selected from silver, copper, gold, platinum, nickel, aluminum, cobalt, combinations thereof or alloys thereof.

[0031] The metal oxide of the metal oxide nanoparticles is advantageously chosen from ZnO, TiO2, ITO (indium tin oxide) or V2O5.

[0032] The quantum dots may advantageously be as described, for example, in EP2820108, US2014353579 or WO2023274486. In other words, it is an additive that promotes the dispersion of metal particles in the ink and particularly enhances the stability of the ink.

[0033] Advantageously, the ink comprises 0.5% to 5% by volume of dispersant relative to the total volume of the ink, advantageously 1% to 2% by volume.

[0034] The dispersing agent is advantageously selected from polyvinylpyrrolidone (PVP), gum arabic, polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyallylamine (PAAm), polysodium styrene sulfonate (PSS), 3-(aminopropyl)trimethylsilane (APS), fatty acids, cetyltrimethylammonium bromide (CTAB), tetraoctylammonium bromide (TOAB), sodium citrate, laurylamine, dodecanethiol, mercaptopolyethylene glycol, mercaptopolypropylene glycol, or combinations thereof.

[0035] The dispersant may be a polymer having a number average molecular weight Mw of 5,000 g / mol to 2,000,000 g / mol. The dispersant is preferably PVP. The molecular weight Mw of the PVP is advantageously at least 8,000 g / mol, more advantageously 10,000 g / mol to 1,600,000 g / mol, and even more advantageously 10,000 g / mol to 200,000 g / mol. When the nanoparticles are silver or copper nanoparticles, the dispersant is advantageously selected from polyvinylpyrrolidone (PVP), gum arabic, polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyallylamine (PAAm), polysodium styrenesulfonate (PSS), 3-(aminopropyl)trimethylsilane (APS), fatty acids, cetyltrimethylammonium bromide (CTAB), tetraoctylammonium bromide (TOAB), sodium citrate, laurylamine, or a combination thereof.

[0036] When the nanoparticles are gold nanoparticles, the dispersing agent is advantageously selected from mercapto-polyethylene glycol, mercapto-polypropylene glycol, dodecanethiol, sodium citrate, polyvinylpyrrolidone (PVP), or a combination thereof. The dispersing agent is preferably mercapto-polyethylene glycol. The molecular weight Mw of the mercapto-polyethylene glycol is advantageously at least 100 g / mol, more advantageously between 400 g / mol and 2000 g / mol.

[0037] The solvent must first allow dispersion of the nanoparticles without significant aggregation in the ink. The inks are often commercially available, and the solvents used already allow good dispersion of the nanoparticles. In some cases, miscible solvents are added to these commercially available inks to adjust their volatility.

[0038] If the metal particles are silver or copper, examples of solvents that allow their good dispersion and that are suitable for the method according to the invention are, in particular, alcohols, glycols, glycol ethers, and mixtures thereof. Of course, mixtures of miscible solvents can also be chosen.

[0039] If the metal particles are gold, examples of solvents which allow their good dispersion and which are suitable for the method according to the invention are in particular water, alcohol, toluene and mixtures thereof. Of course, it is also possible to choose mixtures of miscible solvents.

[0040] In addition to its ability to disperse nanoparticles, the solvent must be sufficiently volatile to allow the formation of a solid phase. Indeed, upon contact between the injector nozzle and the substrate, the solvent should evaporate quickly enough to allow localized concentration / accumulation of nanoparticles, while limiting or preventing the ink from spreading on the substrate.

[0041] On the other hand, the solvent must not evaporate too quickly to avoid clogging of the outlet of the injector discharge orifice.

[0042] The solvent or solvent mixture is therefore advantageously suitable to allow the formation of a solid phase while avoiding, on the one hand, the formation of plugs or breakage of the deposit, and, on the other hand, to avoid or limit the spreading of the ink on the substrate.

[0043] The evaporation rate of the solvent depends of course on the volatility of the solvent, which itself depends on the conditions of use (temperature, pressure, ambient humidity, withdrawal speed of the substrate and the ejection orifice, diameter of the ejection orifice), but also on the volume fraction of nanoparticles in the ink.

[0044] Thus, depending on the conditions of use, the ink may consist of a solvent or solvents, where the solvents are miscible with each other.

[0045] In particular, the addition of a second solvent with low volatility allows for sufficient handling time between the formation of the two structures.

[0046] The inventors believe, without intending to be limiting, that the characteristic time τ for evaporation of the solvent corresponds to the following equation:

number

[0047] Alternatively, without intending to be bound by theory, based on the work of Davis and Ray (J. Chem. Phys. 67, 414 (1977)), the inventors hypothesize that the evaporation rate of the solvent in the ink droplet follows the equation:

[0048]

number

[0049] Integration leads to the conclusion that the evaporation time τ of the solvent is proportional to:

[0050]

number

[0051] If the solvent is a mixed solvent, p vap , ρ liq , D 12 The value of is of course an average value weighted as a function of the volume fraction of each solvent. These relationships have been verified by experimental measurements and are believed to show that the proportionality coefficient is substantially equal to unity.

[0052] Advantageously, the conditions of the diameter of the exit orifice, the saturated vapor pressure of the solvent or solvent mixture, the density of the solvent or solvent mixture, and the volume fraction of the nanoparticles are such that the characteristic time τ for evaporation of the solvent varies from 0.1 to 1000 seconds, in particular from 0.1 to 300 seconds, advantageously from 1 to 30 seconds, more advantageously from 2 to 10 seconds. Preferably, the conditions of the radius of the exit orifice, the saturated vapor pressure of the solvent or solvent mixture, the density of the solvent or solvent mixture, and the volume fraction of the nanoparticles are such that the characteristic time τ for evaporation of the solvent varies from 10 to 300 seconds, in particular from 30 to 300 seconds, advantageously as determined according to equation 4.

[0053] The two equations, Equation 2 and Equation 4, confirm that as the volume fraction of nanoparticles in the ink increases, the volatility of the solvent must decrease.

[0054] It was also confirmed that when the evaporation rate of the solvent is low, the extraction speed needs to be reduced. Advantageously, the volume fraction of nanoparticles in the ink, the radius of the exit orifice (108) and the solvent are selected such that the characteristic time τ for evaporation of the solvent (advantageously determined according to equation 4) varies between 10 and 300 seconds, in particular between 30 and 300 seconds (temperature and gas are generally fixed as 300 Kelvin and air, respectively).

[0055] Advantageously, the volatile solvent is selected from the group consisting of water, alcohols, glycols, glycol ethers and mixtures thereof. In the case of a mixed solvent, the solvents must be miscible and the mixture must be continuous to ensure the function of dispersing the nanoparticles.

[0056] Examples of alcohols include methanol, ethanol, isopropanol, 1-propanol, benzyl alcohol, terpineol, among others. Examples of glycols include ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, diethylene glycol and triethylene glycol, among others.

[0057] Examples of glycol ethers include, in particular: - ethylene glycol ether, propylene glycol ether; - propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol mono-t-butyl ether, propylene glycol monophenyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, propylene glycol mono-t-butyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether; Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol mono-t-butyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether. In particular, the solvent is selected from water, ethanol, ethylene glycol (EG), diethylene glycol methyl ether (DGME), diethylene glycol ethyl ether (DGEE), diethylene glycol butyl ether (DGBE), triethylene glycol methyl ether (TGME), propylene glycol ethyl ether (PGME), tripropylene glycol methyl ether (TPME), and mixtures thereof.

[0058] Advantageously, the ink consists of 80% to 99.45% by volume of said solvent relative to the total volume of the ink, this content corresponding to the contents of the first and second solvents, if present, as defined below.

[0059] This solvent, also called the first solvent, can be used alone or in combination with a less volatile solvent, called the second solvent. As mentioned above, the ink may contain a second solvent that is much less volatile than the first solvent. This second solvent is advantageously hygroscopic. Advantageously, the volatile solvent therefore consists of a second solvent selected from glycerol, advantageously with a content such that the ink consists of 0% to 25% by volume of glycerol relative to the total volume of the ink.

[0060] The purpose of having the second solvent present is to prevent rapid drying and clogging of the exit orifice. Depending on the humidity of the air and the volume fraction of the second solvent, the exit orifice can be left in air for 1 to 30 minutes before resuming nanostructure formation. Thus, for example, it is possible to create nanostructures one after the other with a time interval of 30 seconds to 30 minutes between each one without clogging the exit orifice between the two nanostructures.

[0061] Advantageously, the ink consists of four components, more advantageously: - the aforementioned nanoparticles in a volume concentration ranging from 0.05 vol% to 15 vol%, preferably from 4 vol% to 8 vol%; - the aforementioned dispersant in a volume concentration ranging from 0.5% to 5% by volume, preferably from 1% to 2% by volume; a first solvent selected from water, ethanol, ethylene glycol (EG), diethylene glycol methyl ether (DGME), diethylene glycol ethyl ether (DGEE), diethylene glycol butyl ether (DGBE), triethylene glycol methyl ether (TGME), propylene glycol ethyl ether (PGME), tripropylene glycol methyl ether (TPME), and mixtures thereof; -0 to 25 vol% glycerol The percentages are expressed by volume relative to the total amount of ink. When the ink is made up of these four components, it is made up of 55% to 99.45 vol% of the first solvent.

[0062] Three-dimensional nanostructure manufacturing system FIG. 2 illustrates one embodiment of a system 10 for fabricating three-dimensional nanostructures on a substrate 20 . In this case, the system 10 comprises all the functions of a system for controlled deposition of ink on a substrate as presented in application WO2012 / 078590, which is incorporated by reference, and to which reference may be made for details regarding known aspects of the implemented technology.

[0063] The system 10 for fabricating three-dimensional nanostructures on a substrate 20 consists of a nanometer-sized injector 100 .

[0064] The injector 100 comprises a reservoir 102 for storing ink and a non-deformable protrusion 104. The injector 100 has an exit orifice 108 for extracting ink from the reservoir 102.

[0065] The diameter of the discharge orifice 108 is between 0.1 and 50 μm, advantageously between 0.5 and 30 μm.

[0066] The system 10 also comprises a conveyor or movement means 160 suitable for moving the substrate 20 relative to the injector 100. This movement can be in directions x and y parallel to the substrate, as well as in a direction z not parallel to the substrate. The movement means 160 can be a piezo scanner on which the substrate 20 is deposited, in particular a three-axis piezo scanner with sub-nanometric movement resolution.

[0067] The system 10 further comprises a mechanical resonator attached to the injector 100 . The mechanical resonator may be in the form of a diapason, the body of which is screwed to a base on a block that moves along three spatial axes via a system of micrometric screws.

[0068] The system 10 further comprises a mechanical resonator controller or control means 148. The controller 148 consists of a first PID controller 1 connected to an excitation device or excitation means 142 suitable for exciting the mechanical resonator.

[0069] The system 10 comprises an excitation means 142, which may be a piezoelectric exciter, which is glued onto a mechanical resonator.

[0070] The control means 148 is further connected to a detector or detection means 144 suitable for detecting vibrations of the mechanical resonator so as to read the response of the mechanical resonator to the excitation of the excitation means 142. The system 10 comprises a detector 144, which may be an accelerometer, attached to the mechanical resonator. The detector 144 is capable of detecting oscillation variations, in particular variations of the oscillation frequency of the injector below 1 Hz, advantageously between 10 mHz and 200 mHz.

[0071] The control means 148 is further connected to an adjuster or adjusting means 146 suitable for adjusting the contact between the protrusions 104 and the substrate 20 by controlling the vibration of the mechanical resonator.

[0072] The system 10 comprises a second PID controller 2, the regulator 146, which allows for the regulation of the contact points with the conveyor or moving means 160 to which it is connected.

[0073] Regarding the excitation of the resonator, it should be noted that the piezoelectric exciter can be powered by an electrical signal whose frequency corresponds to its mechanical excitation frequency. The frequency of this electrical signal is adjusted by a first PID controller 1 to control the vibration of the diapason so that the response of the diapason detected by the accelerometer is in phase with the signal of the piezoelectric exciter. Therefore, the setpoint of this feedback loop is to achieve zero phase shift between the oscillation of the piezoelectric exciter and the oscillation of the diapason. Thus, the diapason is in phase with the piezoelectric exciter. The diapason is thus excited at a resonant frequency that depends not only on its mechanical properties but also on its interaction with the environment.

[0074] The control means 148 is adapted to cause the injector 100 to deposit the ink as described above onto the substrate 20 while the injector is in contact with the substrate 20. The control means 148 is connected to the conveyor 160 and is adapted to withdraw the injector from the substrate 20 in a z-direction that is not parallel to the substrate while maintaining a flow of ink out of the injector. The z-direction may be perpendicular to the plane of the substrate 20.

[0075] Manufacturing method for three-dimensional nanostructures The manufacturing system is capable of carrying out the method according to the present invention for manufacturing three-dimensional nanostructures.

[0076] One embodiment of this method is as follows. The first step in the method is to oscillate the injector 100 between a low position where it contacts the substrate 20 and a high position where it does not contact the substrate 20 . Typically, the injector oscillates during this step with an amplitude in the range of 0.5 to 100 nm, advantageously 1 to 20 nm.

[0077] For this purpose, the control means 148 can control the excitation means 142 to excite a mechanical resonator which itself causes the injector 100 to vibrate. The protrusions 104 therefore oscillate between a low position in which the protrusions 104 are in contact with the substrate 20 and a high position in which the protrusions 104 are not in contact with the substrate 20.

[0078] The resonance of a system consisting of a diapason, a piezoelectric exciter, and an acceleration sensor can be measured to determine the resonant frequency of the diapason and its quality factor.

[0079] It is also possible to predefine a setpoint oscillation phase shift of the second PID controller 2, which corresponds to a phase shift induced by a predefined contact between the protrusion and the substrate 20. For example, this phase shift may be less than 1 Hz and may advantageously be in the range of 10 mHz to 200 mHz (millihertz).

[0080] The substrate 20 is approached by the protrusions 104 using the conveyor 160 so that the protrusions 104 oscillate between a low position where they are in contact with the substrate 20 and a high position where they are not in contact with the substrate 20. This particular configuration of the protrusions 104 and the substrate 20 changes the force applied to the assembly formed by the diapason and the injector 100. This changes the resonant frequency and therefore the excitation frequency of the piezoelectric exciter which is held at the resonant frequency of the diapason.

[0081] It is possible to choose to define this configuration by a specific modification of the resonant frequency of the assembly formed by the diapason and the injector 100, for example a modification of less than 1 Hz, advantageously in the range of 10 mHz to 200 mHz. This modification is the induced phase shift mentioned above.

[0082] The system 10 is suitable for identifying, via the detector 144, a particular configuration between the injector and the substrate with vibration fluctuations below 1 Hz, advantageously in the range of 10 mHz to 200 mHz.

[0083] A second PID controller 2 can be used to adjust the configuration for forming an ink meniscus between the protrusion 104 and the substrate 20 as a function of the vibration variations. The regulator or second PID controller 2 controls the fine proximity between the substrate 20 and the injector 100 via a feedback loop until the correction of the resonant frequency is less than 1 Hz, advantageously in the range of 10 mHz to 200 mHz.

[0084] The second step of the method is to deposit the ink onto the substrate 20 by the injector 100 while the injector is in contact with the substrate 20 .

[0085] When contact is made, a meniscus of the liquid contained in the pipette (ink as previously described) appears between the exit orifice 108 and the substrate 20 (see Figure 1).

[0086] Contact is maintained by constraining the frequency shift of the resonance, which shift is due to the interaction between the discharge orifice 108 and the substrate 20. The value of the "frequency shift" used is advantageously between 40 mHz and 500 mHz. As previously indicated, the amplitude of vibration of the diapason, and therefore of the protrusions 104, is fixed between 0.5 nm and 100 nm.

[0087] The ink thus deposited on the substrate becomes the basis for the three-dimensional nanostructures that are fabricated. The method may include a subsequent third step, followed by a step of maintaining contact without withdrawing from the injector 100. This step, corresponding to the initiation time, allows the meniscus formed by the nanoparticles to be concentrated. Therefore, the more diluted the ink, the more advantageous it is to observe the initiation time. This initiation time advantageously varies from 1 second to 180 seconds.

[0088] The third step in the method is to withdraw the injector 100 from the substrate 20 in a non-parallel direction, preferably substantially perpendicular, while maintaining the flow of ink from the injector.

[0089] In this process, the ink emerging from the injector is deposited on top of the previously deposited ink, gradually forming three-dimensional nanostructures, the nanostructures thus produced consisting of portions extending in a direction non-parallel to the substrate, preferably substantially perpendicular to the substrate.

[0090] As indicated above, the suction speed of the injector is adjusted so that the ejected ink solidifies fairly quickly to act as a base for the precipitation of subsequently ejected ink.

[0091] For example, the system can be adjusted so that during this step the injector is withdrawn at a predetermined speed of less than 10, advantageously in the range of 1 μm / s to 10. Advantageously, once contact is established, the substrate 20 is withdrawn from the protrusions 104 according to one of the following two manners:

[0092] 1) The feedback control loop of the moving means 160 via the regulator 146 (PID controller 2) is kept active: The appearance of the solid phase induces localized irregularities on the substrate, resulting in a frequency shift that is detected by the phase-locked loop. The moving means 160 responds to this increase in frequency shift by retracting the substrate 20 sufficiently to find a fixed frequency shift setpoint, between 40 mHz and 500 mHz. This initiates pillar formation. This routine continues autonomously as long as the operator leaves the feedback control loop active and pillars are continuously retracted from the tip of the discharge orifice 108. Deactivating the feedback control loop of the moving means 160 interrupts pillar formation. The pillars obtained according to this variant have an advantageously smooth appearance (FIGS. 3A, 3C). If the settings are varied, the pillars can be given an undulating shape (FIG. 3E).

[0093] 2) The feedback control loop of the moving means 160 is released via the regulator 146 (PID controller 2): Immediately after the meniscus is formed, the operator waits 1 to 60 seconds in contact to initiate pillar formation before using the control software to manually pull the substrate 20 from the protrusion 104. The distance increments are 0.01 to 10 μm, and the pull-off speed is 0.01 μm / s to 10 μm / s. Advantageously, there can be a start time between each distance increment of 0.1 to 60 seconds. The pillars obtained according to this modification have an advantageously layered appearance (Fig. 3B, 3D).Varying the drawing speed can give the pillars an undulating shape.

[0094] In either case, to peel the protrusions 104 from the pillars, in the fourth step (also called the breaking step), the substrate is pulled at a speed of at least 10 μm / s. It is known that the faster the pulling speed (>500 μm / s), the flatter the top of the pillars will be (Figures 3C and 3D). In contrast, if the pulling speed is too slow (<20 μm / s), the top of the pillars will be conical, and the slower the pulling speed, the more elongated the cone will be (Figures 3A and 3B).

[0095] This method reduces the strut manufacturing time to approximately a few seconds. This method can be done without using a camera to monitor and control the deposition, and it makes it possible to overcome the pressure forces on the ink being deposited. It is therefore possible to fabricate nanostructured pillars with aspect ratios greater than 1, advantageously in the range of 10:1 to 50:1, such as pillars with a diameter of 1 μm and a length of 30 μm. Such pillars are obtained in particular using injectors whose exit orifices 108 have a diameter ranging from 0.1 μm to 50 μm, advantageously from 0.5 μm to 30 μm, and more advantageously from 1 μm to 15 μm.

[0096] The shape of the pillars varies depending on the conditions of use. As shown in Example 1 and Figure 3, the pillars can be formed to have the following characteristic shapes: - a smooth column of substantially constant diameter, terminating in a conical apex (Fig. 3A); - a stratified column of substantially constant diameter, terminating in a conical apex (Fig. 3B); -smooth cylinder with a substantially constant diameter ending in a flat top (Fig. 3C); - stratified columns of substantially constant diameter, terminating in a flat top (Fig. 3D); - smooth cylinder with variable diameter and undulating shape (Fig. 3E); -The columns have alternating smooth and stratified zones (Fig. 3F); - Rounded conical pin-shaped pillars, with a decreasing diameter along their height (Fig. 3G).

[0097] The method advantageously further comprises relatively moving the injector in a direction (x, y) parallel to the substrate (20) to deposit ink to form at least one line, according to the method described in WO2020 / 128310.

[0098] The method can be adapted for continuously producing a plurality of nanostructures, and to this end, the method can further comprise performing at least one cycle of the following steps to form at least one second three-dimensional nanostructure: - moving the injector relative to the substrate 20 in a direction (x, y) parallel to the substrate; - Carrying out the steps of the method indicated above.

[0099] The relative movement is ensured by a movement means 160. During the relative movement of the injector with respect to the substrate (20) in a direction (x, y) parallel to the substrate, ink can be deposited to form at least one line according to the method described in WO 2020 / 128310. Each time a cycle of the process is performed, a new nanostructure is produced.

[0100] Once the posts or pillars have been formed, the method advantageously includes a curing step, the conditions of which can be adjusted as a function of the metal or oxide nature of the nanoparticles. For example, pillars made of gold or silver are heated to a temperature ranging from 130°C to 200°C for a time that can vary from 10 minutes to 2 hours. For copper posts, the temperature and time conditions are the same, and it is only necessary to operate under a non-oxidizing atmosphere, such as argon, nitrogen, or hydrogen. Photocuring can also be performed, even for copper posts, under ambient atmosphere. Advantageously, all steps of the method are carried out at ambient temperature (18-22°C) and atmospheric pressure.

[0101] Furthermore, the present invention relates to a product comprising a substrate on which three-dimensional nanostructures are deposited, obtained by a method such as described above.

[0102] According to another embodiment, such nanostructures are columns as previously described, preferably having an aspect ratio greater than 10:1, more preferably greater than 15:1, and even more preferably in the range of up to 50:1, and extending in an elongation direction at least 10 times greater than the width of the nanostructure in a direction perpendicular to the elongation direction. The extension direction corresponds to a z-direction non-parallel, advantageously substantially perpendicular, to the substrate, in which z-direction the injector is withdrawn from the substrate during the method.

[0103] The base diameter of the column, which corresponds to its maximum width, is advantageously less than 10 μm, more advantageously less than 5 μm, even more advantageously less than 2 μm, for example 1 μm.

[0104] According to another option, such nanostructures are pins as previously mentioned. Controllable parameters include the diameters of the base and top of the pin, and the angle of the slope formed between the vertical wall of the pin and the axis perpendicular to the substrate. The diameter of the base is preferably 0.5 μm to 50 μm, more preferably 1 to 30 μm. The diameter of the apex is preferably 0.2 μm to 30 μm, more preferably 0.5 μm to 10 μm. The angle of the slope formed between the vertical wall and the axis perpendicular to the substrate preferably varies from 0.1° to 70°, more preferably 10° to 45°.

[0105] This shape is of interest when manufacturing solder bumps in the packaging process for electronic chips. Conical pins are more mechanically stable than cylindrical pins when subjected to shear stress. This typically occurs during wafer bonding, where pins deposited on a silicon wafer are compressed vertically by the pressure of the silicon wafer. Small movements in the x and y directions of the silicon wafer during compression can misalign the columns and impair proper bonding of the two silicon wafers. Due to their morphology, conical pins are less susceptible to this phenomenon. Advantageously, in any one of the variants, the substrate is non-conductive. [Example]

[0106] The following examples illustrate the invention.

[0107] Characteristic times required for evaporation of several solvents Using Equation 4 with the following parameters: x NP is set to 0.06. 2a (pipette diameter) = 1.5 * 10 -5 m R=8.3JK -1 .mol -1 T=300K D 12represents the diffusion coefficient of solvent (1) in air (gas (2)). It is calculated using the Chapman-Enskog equation:

[0108]

number

[0109] In the above formula, [Table A] p vap represents the saturated vapor pressure of the solvent at a temperature of 300K. ρ liq represents the density of the ink solvent at a temperature of 300K.

[0110] [Table B]

[0111] The characteristic time required for evaporation of the solvent was measured using the experimental apparatus described in Examples 1 to 10. The experimental values were in excellent agreement with the theoretical values obtained according to Equation 4. In particular, when the pipette diameter was 1.5*10 -5 In the case of m, TEG alone or glycerol alone are solvents that are not volatile enough to solidify the ink once it has been deposited.

[0112] Example 1: Silver nanoparticles - commercial ink Commercially available ink PVnanocell ref (Sycris (商標) I40DM-106), consisting of the composition indicated by the supplier: -Silver nanoparticles (d50=70nm, d90=152nm, Lumisizer (商標) (measured by vol. 1) is coated with a layer of polyvinylpyrrolidone, the mass concentration of which is 38% to 42% or approximately 5.8 vol.%.

[0113] -Solvent DGME The liquid is injected into a drawn glass capillary (=pipette) with a tip diameter shown in Table 1, taking care to ensure that the liquid reaches the tip of the pipette. Following the method described in Figure 2 of WO2020 / 128310, the pipette is fixed to one of the two tines of the diapason and its tip is brought close. In the first step, the pipette tip is mechanically brought within 300° of the substrate (in this case, a silicon wafer) using a micrometric vernier. Next, the approach to contact with the substrate is controlled using a loop (phase-locked loop (PLL)) that maintains the diapason's resonance and a feedback control loop of the piezo scanner to ensure contact between the pipette tip and the substrate. The substrate is placed on the piezo scanner, the pipette is fixed, and the substrate is brought close to the pipette. Contact is maintained by constraining the frequency shift (FS) of the resonance, which arises from the interaction between the pipette and the substrate. The value of FS used is 150 mHz (millihertz).

[0114] The vibration amplitude of the diapason (and therefore the pipette) is fixed at 10 nm. Upon contact, a meniscus of the liquid (ink) contained in the pipette appears between the tip of the pipette and the substrate.

[0115] Once contact is established, the substrate is withdrawn from the pipette according to one of two modes: 1) Keep the feedback control loop of the piezo scanner active: The appearance of the solid phase creates localized irregularities on the substrate, which are detected by the PLL. The piezo scanner responds to this increase in FS by pulling away from the substrate sufficiently to return the FS to its fixed setting of 150 mHz, thus initiating pillar generation. This routine continues autonomously as long as the operator keeps the feedback control loop active and pillars are continuously drawn from the tip of the pipette. Pillar generation is aborted when the piezo scanner feedback control loop is stopped. To detach the pipette from the pillar, withdraw it at a speed of at least 10 μm / s. 2) Stop the feedback control loop of the piezo scanner: Immediately after the meniscus is formed, the operator waits 1 to 60 seconds to initiate pillar formation, then manually pulls the substrate away from the pipette using the control software, in increments of 0.01 to 10 μm, at speeds of 0.01 to 10 μm. To detach the pipette from the pillar, proceed as above. All steps of this method are carried out at room temperature (18-22°C) and atmospheric pressure. The results obtained are summarized in the following table:

[0116] [Table 1]

[0117] D = pipette diameter (μm) Ve = separation velocity (μm / s) Vr=Rupture velocity (μm / s) The following figures are shown: - Figure 4A: Pillar obtained according to test 3; - Figure 4B: Pillars obtained in test 4; Figure 4C: Flattened dome from test 8

[0118] The 30 mm diameter pipette provides a higher ratio of deposition area to volume of the deposited ink. A more volatile solvent than DGME is required to solidify the nanoparticles more quickly and obtain pillars with a consistent diameter along their height. In test 8, the drawing speed was too fast to form pillars. In test 9, the pillars were pulled but did not form a column of substantially constant diameter. Then, cure it on a hot plate at 150°C for 30 minutes.

[0119] Example 2: Silver nanoparticles - diluted commercial ink The ink of Example 1 is diluted with the same solvent DGEE so that the volume concentration of nanoparticles is 5 vol% (=35 wt%). Pipettes with tip diameters of 1.5 μm or 8 μm are used to perform approach and contact as in Example 1. No feedback control loop is activated. The results obtained are summarized in the following table:

[0120] [Table 2]

[0121] D = pipette diameter (μm) Ve = separation velocity (μm / s) Vr=Rupture velocity (μm / s) The high dilution of the ink and the large amount of liquid that must be evaporated to obtain a solid phase of nanoparticles result in a slower withdrawal speed. Then, cure it on a hot plate at 150°C for 30 minutes.

[0122] Example 3: Silver nanoparticle-enriched commercial ink The ink of Example 1 is centrifuged at 7000 rpm for 30 minutes to remove the solvent DGME and increase the concentration of nanoparticles. Glycerol was added as a second solvent to give the following formulation: - nanoparticles: 10 vol%; -DGME: 65 vol%; -Glycerol: 25 vol%. Pipettes with tip diameters of 1.5 or 8 μm are used to perform approach and contact as in Example 1. The feedback control loop is stopped. The results obtained are summarized in the following table:

[0123] [Table 3]

[0124] D = pipette diameter (μm) Ve = separation velocity (μm / s) Vr=Rupture velocity (μm / s)

[0125] The ink is allowed to settle and drawn to form a column without clogging the pipette. The low volatility of glycerol results in a high volume fraction of nanoparticles. Then, cure it on a hot plate at 150°C for 30 minutes.

[0126] Example 4: Silver nanoparticles - commercial ink The ink used was PVnanocellref (Sycris (商標) P75DB-1) is a commercially available ink, and the supplier's formulation is as follows: -Silver nanoparticles coated with a polyvinylpyrrolidone layer (d50=70nm, d90=130nm, Lumisizer (商標) (measured by ); the mass concentration is 72-78 wt%, i.e., approximately 10 vol%. -Solvent DGBE. Approach and contact are performed using a pipette with tip diameters as shown in the table below, as described in Example 1. The feedback control loop is turned off. The results obtained are summarized in the following table:

[0127] [Table 4]

[0128] D = pipette diameter (μm) Ve = separation velocity (μm / s) Vr=Rupture velocity (μm / s)

[0129] The solvent DGBE is less volatile than DGME and therefore evaporates slower than DGME under the same temperature and pressure conditions, resulting in a slower extraction rate. Then, cure it on a hot plate at 150°C for 30 minutes.

[0130] Comparison Test 1 : The ink of Example 1 is centrifuged at 7000 rpm for 30 minutes to remove the solvent DGME and increase the concentration of nanoparticles. - nanoparticles: 16 vol%; -DGME: 84 vol%; Approach and contact were performed using a pipette with an 8 μm tip diameter, as described in Example 1. The pipette was inserted too quickly to form pillars. No matter how fast the pipette was withdrawn, only a small number of particles were deposited on the substrate (see Figure 5).

[0131] Example 5: Copper nanoparticles - diluted commercial ink Commercially available ink PV nanocellref (Sycris TM IC50DM-7) consists of the composition indicated by the supplier: Copper nanoparticles coated with a polyvinylpyrrolidone layer (d50=50 nm, d90=120 nm, measured with Lumisizer™); mass concentration between 48% and 52%, i.e., approximately 9.8 vol%. -solvent DGME, Dilute the ink with DGME or DGEE and glycerol in a volume ratio of 70:15:15 (ink:DGEE / DGME:glycerol). The resulting volume fraction is 6.5 vol% of copper nanoparticles. Approach and contact are performed using a pipette with a tip diameter of 5 or 10 μm as described in Example 1. The feedback control loop is stopped. Thereafter, the resin is cured on a hot plate at 150°C for 30 minutes in a nitrogen atmosphere.

[0132] The results obtained are summarized in the following table:

[0133] [Table 5]

[0134] D = pipette diameter (μm) Ve = separation velocity (μm / s) Vr=Rupture velocity (μm / s) Examples of photographs are shown in Figure 6. Figure 6A: D=5, Figure 6B: D=10.

[0135] Example 6: Copper nanoparticles - diluted commercial ink Commercially available ink PV nanocellref (Sycris (商標) IC50DM-7) consists of the composition indicated by the supplier:

[0136] - Copper nanoparticles coated with a polyvinylpyrrolidone layer (d50=50nm, d90=120nm, Multisizer (商標) (measured at 48%-52%), or approximately 9.8 vol%. -Solvent DGME The ink was diluted with DGME or DGEE and glycerol to a volume ratio of 50:40:10 - ink:DGEE / DGME:glycerol, resulting in a volume fraction of 4.9 vol% copper nanoparticles.

[0137] Approach and contact are performed using a pipette with a tip diameter of 5 μm as described in Example 1. The feedback control loop is turned off. Thereafter, the resin is cured on a hot plate at 150°C for 30 minutes in a nitrogen atmosphere. The results obtained are summarized in the following table:

[0138] [Table 6]

[0139] Ve = separation velocity (μm / s) Vr=Rupture velocity (μm / s) Figure 7 shows the photograph corresponding to test 32.

[0140] Comparative Example 2 The commercially available ink PVnanocellref (Sycris IC50DM-7) has the composition indicated by the supplier: copper nanoparticles coated with a polyvinylpyrrolidone layer (d50=50 nm, d90=120 nm, measured with a Multisizer™); their mass concentration is between 48% and 52%, i.e., about 9.8 vol%. -solvent DGME, Dilute with glycerol in a 50:50 volume ratio. The volume fraction thus obtained was 4.9 vol% copper nanoparticles.

[0141] To form pillars, we used a pipette to deposit lines and dots of nanoparticle-containing ink, following the same routine as before (see Figures 8A and 8B), but we were unable to form pillars even at a pull-off speed 0.01 times slower. Even after the DGME has completely evaporated, there is still enough glycerol remaining to keep the ink liquid and prevent the nanoparticles from solidifying.

[0142] Example 7: Gold nanoparticles - commercial ink Lab-grown gold ink: - Gold nanoparticles coated with a dispersant layer (d50 = 6 nm and d90 = 10 nm, determined by dynamic light scattering (DLS)); volume concentration 0.4 vol%. - Use of ethanol as component 1 of the first solvent at a level of 59.6 vol%; - using water as component 2 of the first solvent at a level of 30 vol.%; - Glycerol was used as the second solvent at a level of 10 vol%, is injected using a pipette with a diameter of 1.5 or 8 μm. The feedback control loop is stopped. The rupture speed is 100 μm / s. Then, the resin is cured on a hot plate at 200°C for 30 minutes. The results obtained are summarized in the following table:

[0143] [Table 7]

[0144] D = pipette diameter (μm) Ve = separation velocity (μm / s) Figure 9 is a photograph corresponding to test 35.

[0145] Example 8: Variation of pull-off speed with pipette diameter The ink of Example 1 was used to form pillars according to the protocol detailed in Example 1. The maximum speed at which pillars could be formed without rupturing the meniscus is reported as a function of the diameter of the pipette used in the graph of Figure 10A and as a function of the volume fraction of nanoparticles in the graph of Figure 10B.

[0146] The diameter of the pipette ranges from 1 to 30 μm. It is observed that the larger the pipette diameter, the slower the withdrawal speed must be to form pillars. The surface area / volume ratio increases, and the time required to evaporate the solvent increases with the size of the meniscus, i.e., the diameter of the pipette.

[0147] The volume fraction varies between 0 and 6 vol%. The higher the volume fraction occupied by nanoparticles, the faster the pull-out speed to form the pillars. With a higher volume fraction of nanoparticles, less solvent is evaporated, and solidification of the ink in the meniscus is achieved more quickly.

[0148] Example 9: Conductive lines connected to silver or copper pillars Here, the inks of Examples 4 (for silver) and 6 (for copper) were used to deposit conductive lines and then pillars; Runs 36 and 37, respectively.

[0149] Approach and contact are performed as described in Example 1 using a pipette with a 5 μm tip diameter. Once the pipette makes contact, the PLL loop is kept active to keep the pipette in close contact with the surface and avoid meniscus rupture. The substrate is moved horizontally at a speed of 1-1000 μm / s, depositing ink along the path traced by the pipette on the substrate. Once a line of nanoparticles is formed, the pipette remains stationary in contact for 1-30 seconds, after which the substrate is withdrawn from the pipette (the feedback control loop is deactivated) as described in Example 1. This results in a pillar. Then, the resin is cured on a hot plate at 150°C for 30 minutes (in a nitrogen atmosphere in the case of copper). The results obtained are summarized in the table below.

[0150] [Table 8]

[0151] Ve = separation velocity (μm / s) Vr=Rupture velocity (μm / s) Figure 11 is a photograph corresponding to test 37.

[0152] Example 10: Silver nanoparticles - commercial ink In this example, the ink of Example 1 was used. A 4 diameter pipette is used for injection according to the protocol detailed in Example 1. A feedback control loop is activated. The break rate is 100 μm / s. Then, the resin is cured on a hot plate at 200°C for 30 minutes. A pillar with a diameter of 4 mm and a height of 280 mm was obtained (aspect ratio 70). Figure 12 shows an SEM image of this pillar.

Claims

1. A method for manufacturing a three-dimensional nanostructure, comprising the following steps: - A step of oscillating an injector (100) between a lower position in contact with a substrate (20) and a higher position not in contact with the substrate (20), wherein the injector (100) is equipped with an evacuation orifice (108) having a diameter greater than 0.1 μm; - A step of depositing ink onto a substrate (20) by an injector while the discharge orifice (108) of the injector (100) is in contact with the substrate (20), wherein the ink is in a volume % of the total volume of the ink. - Less than 15% nanoparticles selected from metal nanoparticles, metal oxide nanoparticles, graphene oxide nanoparticles, quantum dots, or combinations thereof. A method comprising: - 0.5% to 5% dispersant; - at least 8% solvent (at least 80% solvent, based on the English text) that is volatile enough to disperse metal nanoparticles to form an ink to be injected and to allow the ink to solidify once deposited; and - pulling the injector (100) away from the substrate (20) at a speed of 10 μm / s or less in a direction substantially perpendicular to the substrate, while maintaining the flow of ink coming out of the injector.

2. The method according to claim 1, wherein the ink contains 0.05% to 15% by volume of nanoparticles relative to the total volume of the ink.

3. The method according to claim 2, wherein the ink contains 4% to 8% by volume of nanoparticles relative to the total volume of the ink.

4. The method according to claim 1 or 2, wherein the diameter of the discharge orifice (108) is in the range of 0.1 μm to 50 μm.

5. The method according to claim 1 or 2, wherein the diameter of the discharge orifice (108) is in the range of 0.5 μm to 30 μm.

6. The method according to claim 1, wherein the volatile solvent comprises a solvent selected from water, alcohol, glycol, glycol ether and mixtures thereof.

7. The method according to claim 6, wherein the ink contains 80% to 99.45% by volume of the solvent relative to the total volume of the ink.

8. The method according to claim 6 or 7, wherein the volatile solvent further comprises a second solvent, the second solvent being glycerol.

9. The method according to claim 8, wherein the ink has a glycerol content such that it contains 0% to 25% by volume of glycerol relative to the total volume of the ink.

10. The method according to claim 1 or 2, wherein the metal of the metal nanoparticles is selected from silver, copper, gold, platinum, nickel, aluminum, cobalt, zinc, indium, palladium, and combinations or alloys thereof.

11. The metal oxide of the aforementioned metal oxide nanoparticles is ZnO, TiO ２ , ITO (indium tin oxide) or V ２ O ５ The method according to claim 1 or 2, selected from the above.

12. The method according to claim 1 or 2, wherein the ink further comprises a dispersant.

13. The method according to claim 12, wherein the dispersant is selected from polyvinylpyrrolidone (PPV), gum arabic, polyvinyl alcohol (PVA), polyacrylic acid (PAA), polyallylamine (PAAm), polysodium styrenesulfonate (PSS), 3-(aminopropyl)trimethylsilane (APS), fatty acids, cetyltrimethylammonium bromide (CTAB), tetraoctylammonium bromide (TOAB), sodium citrate, laurylamine, dodecanethiol, mercaptopolyethylene glycol, mercaptopolypropylene glycol, or a combination thereof.

14. The method according to claim 1 or 2, wherein during the step of separating the injector from the substrate, the injector is separated at a speed in the range of 1 μm / s to 10 μm / s.

15. The method according to claim 1 or 2, comprising the step of disrupting the bond between the formed three-dimensional nanostructure and the deposited ink.

16. The method according to claim 15, wherein the destruction step is performed by pulling the injector (100) away from the substrate (20) at a speed greater than 10 μm / s.

17. The method according to claim 1 or 2, further comprising performing at least one cycle of the following steps to form at least one second three-dimensional nanostructure: - moving an injector with respect to a substrate (20) in a direction parallel to the substrate (x, y), and - performing the steps according to claim 1 or 2.

18. The method according to claim 1 or 2, comprising the step of curing a substrate containing the formed nanostructure.

19. A product comprising a substrate on which at least one three-dimensional nanostructure obtained by the method of either Claim 1 or 2 is deposited, wherein the nanostructure is in the form of a conical pin having a diameter decreasing upward and having at least one of the following features: - The diameter of the base is 0.5 μm to 50 μm; - The diameter of the vertex is between 0.2 μm and 30 μm; - The angle of slope relative to the vertical is between 0.1° and 70°.

20. A product comprising a substrate on which at least one three-dimensional nanostructure obtained by the method of claim 1 or 2 is deposited, wherein the nanostructure is in the form of a column having a height of at least 15 times the diameter of its base.

21. The product according to claim 20, wherein the diameter of the base is less than 1 μm.

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