Micro- or nano-structuring process for the surface of a material

Abstract

TITLE: Process of micro- or nano-surface structuring of a material. The invention relates to a method for micro- or nano-structuring the surface of a material, characterized in that it comprises an irradiation step (a) consisting of irradiating a localized surface area of ​​said material with a focused gas ion beam, said beam being defined by: - ​​an ion kinetic energy of between 5 and 30 keV for hydrogen ions, between 10 and 60 keV for helium ions, or between 20 and 500 keV for ions with an atomic mass unit greater than or equal to 12, - a flux fixed at a value between 10¹³ and 10¹⁸ ions / cm² / s, and - a fluence whose value is derived from a database linking the nature of said material, the type of ions used and the associated kinetic energy, and the flux value required to obtain micro- or nano-structuring of the surface of the material. Figure for the abstract: Fig. 1

Description

Title of the invention: Process for micro- or nano-surface structuring of a material Technical field of the invention

[0001] The invention relates to the field of surface micro- or nano-structuring of a material and more particularly to techniques for obtaining hollow micro- or nano-structures on the surface of a material. Technical background

[0002] Lasers can be used to create hollow micro or nano structures on the surface of a material. Thus, document EP1707531A1 proposes the use of a focused laser beam to manufacture buried micro-channels. In this case, the method uses the laser-induced deterioration of a resin added to the surface of the material which will release gas locally to deform the structure by swelling. This technique makes it possible to obtain hollow structures obtained at a minimum depth. For a given material, the positioning in depth, but also the lateral dimensions of the hollow structure obtained are notably linked to the wavelength of the laser.

[0003] It has already been noted that ionic implantation of light elements such as hydrogen (H+) and / or helium (He+) combined with thermal annealing (e.g.: Smartcut™ process) makes it possible to obtain blisters on the surface of a silicon wafer. This technique makes it possible to coalesce these blisters over large surfaces in order to cut the wafers very finely. This technique therefore does not make it possible to obtain localized control of the blisters.

[0004] Generally speaking, the methods described above for micro and / or nano structuring the surface of the material do not make it possible to obtain hollow structures controlled both in depth (or even in protuberance of the surface), in position and / or lateral dimensions. These methods can be described as "direct" in the sense that the aim is to obtain the structuring from the material itself.

[0005] Improved control can however be obtained by "indirect" methods this time, involving successive and / or alternating steps of deposition, growth, lithography, revelation and stabilization. This may involve using hollow micro- or nanospheres deposited on the surface of the material, then carrying out the deposition of a thin layer on top, by techniques such as chemical vapor deposition (better known by the acronym CVD for "Chemical Vapor Deposition" according to English terminology) or atomic layer deposition (better known by the acronym ALD for "Atomic Layer Deposition" according to English terminology). The positioning, in particular on the surface, and the lateral dimensions of the hollow structure are in fact perfectly controlled, but the material forming the hollow sphere serving as support for the deposition of the thin layer remains trapped in the structure finally obtained.

[0006] An objective of the invention is to propose a method for surface micro- or nano-structuring of a material.

[0007] Another objective of the invention is to propose a method for surface micro- or nanostructuring of a material making it possible to obtain hollow micro- or nanostructures on the surface of a material.

[0008] Another objective of the invention is to further propose control of the positioning of the or each hollow micro- or nano-structure as well as its dimensions.

[0009] At least one of the aforementioned objectives is achieved by a method of surface micro- or nanostructuring of a material, characterized in that it comprises a step (a) of vacuum irradiation consisting of irradiating a localized surface area of ​​said material with a focused gas ion beam, said beam being defined by: - an ion kinetic energy of between 5 and 30 keV for hydrogen ions, between 10 and 60 keV for helium ions or between 20 and 500 keV for ions with an atomic mass unit greater than or equal to 12, - a flux fixed at a value between 1013 and 1018 ions / cm2 / s, and - a fluence whose value comes from a database linking the nature of the said material, the type of ions used and the associated kinetic energy, and the value of the flux to obtain a surface micro- or nano-structuring of the material.

[0010] The method according to the invention may comprise at least one of the following additional steps, taken alone or in combination:

[0011] - a step (b) consisting of providing heat to said surface area located, concomitantly or subsequently to step (a);

[0012] - during step (a), the surface of the material is scanned with the ion beam focused;

[0013] - before implementing step (a), a vacuum pre-implantation step consisting of irradiating said localized surface area of ​​the material with types of ions other than those used to implement step (a);

[0014] - during the pre-implantation step, the surface of the material is scanned with the focused ion beam, the scanning carried out during step (a) then being the same as that carried out during pre-implantation;

[0015] - the focused gas ion beam used to implement step (a) comprises at least two different types of ions so as to carry out simultaneous implantation;

[0016] - the micro- or nano-structured material is chosen from: a crystalline material or amorphous, a lamellar-like material such as highly oriented pyrolytic graphite, a thin-film material such as zinc oxide on silicon;

[0017] - the focused gas ion beam used to implement step (a) is generated with rare gases, for example argon or helium, or gases capable of reacting chemically with said material, for example hydrogen, nitrogen or oxygen;

[0018] - the flux is fixed at a value between 1013 and 5.1017 ions / cm2 / s, avanta preferably between 1013 and 1017 ions / cm2 / s, advantageously between 1013 and 5.1016 ions / cm2 / s, still advantageously between 1014 and 5.1016 ions / cm2 / s;

[0019] - the material being highly oriented pyrolytic graphite and the ion beam of focused gas used to implement step (a) being generated with helium, with a flux fixed at a value between 1014 and 6.1016 ions / cm2 / s, the fluence is between 1016 and 1020 ions / cm2, in particular between 2.1016 and 6.1019 ions / cm2;

[0020] - the material being highly oriented pyrolytic graphite and the ion beam of focused gas used to implement step (a) being generated with oxygen at a kinetic energy of between 20keV and 40keV, with a flux fixed at a value of between 1013 and 2.5.1015 ions / cm2 / s, the fluence is between 1015 and 5.1017 ions / cm2, in particular between 4.1015 and 1.5.1017 ions / cm2;

[0021] - the material being highly oriented pyrolytic graphite and the ion beam of focused gas used to implement step (a) being generated with nitrogen at a kinetic energy of 20keV, with a flux fixed at a value between 9.4.1014 and 1.6.1015 ions / cm2 / s, the fluence is between 6.4.1016 and 1017 ions / cm2;

[0022] - the material being highly oriented pyrolytic graphite and the ion beam of focused gas used to implement step (a) being generated with argon at a kinetic energy of 92keV, with a flux fixed at a value between 5.1.1014 and 1.16.1015 ions / cm2 / s, the fluence is between 2.1016 and 5.5.1016 ions / cm2, in particular between 2.3.1016 and 5.1.1016 ions / cm2;

[0023] - the surface micro- or nano-structuring of the material comprises or consists of one or more hollow micro- or nano-structure(s). Brief description of the figures

[0024] Other objects and characteristics of the invention will appear more clearly in the following description, given with reference to the appended figures, in which:

[0025] [Fig. 1] is a representative diagram of the part of the experimental installation named PELIICAEN allowing the implementation of the method according to the invention;

[0026] [Fig.2a] shows the result of implantation of helium at 20keV in crystalline silicon viewed with a scanning electron microscope;

[0027] [Fig.2b] is an enlarged sectional view of the large blister visible in [Fig.2a];

[0028] [Fig.3a] shows the result of implanting oxygen at 20keV into graphite high density pyrolytic, for a given flux, with a first fluence, visualized with a scanning electron microscope;

[0029] [Fig.3b] shows the result of the implantation of oxygen at 20keV in high density pyrolytic graphite, for this same flux given for [Fig.3a], but with a second fluence, visualized with a scanning electron microscope;

[0030] [Fig.3c] shows the result of the implantation of oxygen at 20keV in high density pyrolytic graphite, for this same flux given for [Fig.3a], but with a third fluence, visualized with a scanning electron microscope;

[0031] [Fig.4] shows the result of the implantation of oxygen at 10keV in high density pyrolytic graphite, for a given flux and for different fluences, visualized with a scanning electron microscope;

[0032] [Fig.5a] shows the result of the implantation of oxygen at 40keV in high density pyrolytic graphite, for a given first flux and for different fluences, visualized with a scanning electron microscope;

[0033] [Fig.5b] shows the result of the implantation of oxygen at 40keV in high density pyrolytic graphite, for a given flux lower than the flux given for [Fig.5a] and for different fluences all higher than the fluences of [Fig.5a], visualized with a scanning electron microscope;

[0034] [Fig.6a] shows the result of the implantation of helium at 10keV in crystalline silicon and under flow and fluence conditions adapted to structure the surface of the material, visualized with a scanning electron microscope;

[0035] [Fig.6b] shows the result of hydrogen implantation at 10keV in crystalline silicon and under flow and fluence conditions suitable for structuring the surface of the material, visualized with a scanning electron microscope;

[0036] [Fig.7a] shows the result of the implantation of helium at 10keV in crystalline silicon and under flow and fluence conditions adapted to structure the surface of the material, by carrying out different linear scans, visualized with a scanning electron microscope;

[0037] [Fig.7b] shows the result of the implantation of helium at 10keV in crystalline silicon and under flow and fluence conditions adapted to structure the surface of the material, by performing a circular scan, visualized with a scanning electron microscope

[0038] [Fig.8a] shows the result of helium implantation at 10keV in high density pyrolytic graphite with simultaneous oxygen implantation at 40keV and under flow and fluence conditions suitable for structuring the surface of the material, viewed under a scanning electron microscope;

[0039] [Fig.8b] shows the result of implantation of helium at 10 keV in high density pyrolytic graphite with pre-implantation of oxygen at 40 keV and under flow and fluence conditions adapted to structure the surface of the material, visualized under a scanning electron microscope. Detailed description of the invention

[0040] The invention relates to a method for micro- or nano-surface structuring of a material.

[0041] In the context of the invention, a nano-structure is a structure of which at least two dimensions are less than a micron. Similarly, in the context of the invention, a micro-structure is a structure of which at least two dimensions are less than a millimeter. Still in the context of the invention, the notion of "surface" or "on the surface" designates a structure located at most 1 micron deep.

[0042] The method according to the invention resides mainly in the fact of implementing a (a) vacuum irradiation step consisting of irradiating a localized surface area of ​​said material with a focused gas ion beam characterized, for a given type of ions, by a kinetic energy of these ions in a given range, characterized by a fixed flux in a given range (number of ions per unit of surface and unit of time) and characterized by a fluence (number of ions per unit of surface) judiciously chosen as a function of the other parameters previously cited including the nature of the implanted material.

[0043] By "vacuum" we mean a pressure less than or equal to 106 mbar (also called secondary vacuum). Typically, we can operate at around 108 mbar.

[0044] First of all, the beam ions should have a kinetic energy of between 5 and 30 keV for hydrogen (H), between 10 and 60 keV for helium (He) and between 20 and 500 keV for ions with an atomic mass unit greater than or equal to 12. This range of kinetic energy values ​​makes it possible to manage, depending on the type of ions considered (H, He or other) and as a first approximation, a depth of implantation of the ions in the irradiated material, therefore the positioning in depth of said localized zone. If the kinetic energy is too low, the ions diffuse towards the surface and then do not contribute to a localized accumulation of the gas likely to lead to a structuring of the surface of the material, and in particular to a hollow structure. On the contrary, if the kinetic energy is too great, the gas is accumulated too deep to allow deformation on the surface of the material.The level of kinetic energy also influences the temperature level reached in the localized area, and therefore also possibly the . pressure in this localized area.

[0045] Then, it should be noted that the beam is characterized by a flux fixed at a value between 1013 and 1018 ions / cm2 / s. Fixing the flux in this range makes it possible to manage, as a first approximation, the temperature level reached at the localized zone of irradiation by the ions. For flux values ​​lower than 1013 ions / cm2 / s, swelling of the material can be observed without obtaining a surface structuring, in particular a hollow structure. On the contrary, for flux values ​​higher than 1018 ions / cm2 / s, sputtering effects of the hollow structure can be observed mainly due to excessively high temperatures reached locally. It should also be noted that the temperature level will possibly have an effect on the pressure.

[0046] It should be noted that the flux can be more precisely set at a value between 1013 and 5.1017 ions / cm2 / s, advantageously between 1013 and 1017 ions / cm2 / s, more advantageously between 1013 and 5.1016 ions / cm2 / s, or even more advantageously between 1014 and 5.1016 ions / cm2 / s.

[0047] Finally, it should also be noted that the irradiation is characterized by a fluence (ions / cm2). The fluence makes it possible to manage, as a first approximation, the quantity of gas injected into the irradiated zone and therefore, where appropriate, the pressure within the hollow micro- or nano-structure likely to be generated by the process. For a fluence that is too low, no appearance of any surface structuring is observed, in particular of a hollow structure. On the contrary, for a fluence that is too high, the hollow structure is then of uncontrolled shape or is purely damaged.

[0048] As mentioned, since temperature and pressure are linked, the various parameters mentioned above all contribute, in combination, to defining the geometry of the hollow micro- or nano-structure thus obtained on the surface of the material. By geometry, we mean the shape and dimensions of the hollow micro- or nano-structure. Indeed, the geometry of the micro- or nano-structure depends on the quantity of ions (and therefore gas) implanted at a given energy and on the local rise in temperature so that the material can deform under the effect of the increase in pressure.

[0049] From a practical point of view, once the type of ions carried by the focused gas ion beam has been chosen (H, He or other), we then know in which range the kinetic energy must be located. We also know in which range of fluxes we must operate. On the other hand, the fluence remains to be adapted to obtain a surface micro- or nano-structuring of the material. However, the range of adequate values ​​for the fluence to obtain such a structuring of the surface of the material then depends on the type of ions used (H, He or other) and the associated kinetic energy, and the nature of said material (HOPG for "Highly Oriented Pyrolytic Graphite" according to the terminology Anglo-Saxon which translates as highly oriented pyrolytic graphite, silicon or other).

[0050] During step (a), with the aim of obtaining a surface micro- or nano-structuring of the material, the beam therefore has a fluence whose value comes from a database linking the nature of said material, the type of ions used and the associated kinetic energy, and the value of the flux.

[0051] We present below several examples to give an overview of such a database, in this case for HOPG as material to be implanted, with four types of ions (He, N, O and Ar) and the respective associated kinetic energies.

[0052] Thus and for example, if the material is highly oriented pyrolytic graphite (HOPG) and the focused gas ion beam used to implement step (a) is generated with helium (ion type = helium in this case) at a kinetic energy of 10keV (implantation depth = 82nm), and the flux fixed at a value between 1014 and 6.1016 ions / cm2 / s, then the adequate fluence to obtain a surface micro- or nano-structuring of the material is actually between 1016 and 1020 ions / cm2, in particular between 2.1016 and 6.1019 ions / cm2.

[0053] According to another example, if the material is highly oriented pyrolytic graphite and the focused gas ion beam used to implement step (a) is generated with oxygen (ion type = oxygen in this case) at a kinetic energy between 20 and 40keV (implantation depth of 40nm for 20keV and 75nm for 40keV), and the flux is set to a value between 1013 and 2.5.1015 ions / cm2 / s, then the adequate fluence to obtain a surface micro- or nano-structuring of the material is between 1015 and 5.1017 ions / cm2, in particular between 4.1015 and 1.5.1017 ions / cm2. In this case, it is found that the adequate range of fluence is more restricted than that mentioned for the previous example with helium.

[0054] According to yet another example, if the material is highly oriented pyrolytic graphite and the focused gas ion beam used to implement step (a) is generated with nitrogen (ion type = nitrogen in this case) at a kinetic energy of 20keV (implantation depth of 43nm), and the flux set at a value between 9.4.1014 and 1.6.1015 ions / cm2 / s, then the adequate fluence to obtain a surface micro- or nano-structuring of the material is between 6.4.1016 and 1017 ions / cm2.

[0055] According to a final example, if the material is highly oriented pyrolytic graphite and the focused gas ion beam used to implement step (a) is generated with argon (ion type = argon in this case) at a kinetic energy of 92keV (implantation depth of 77nm), and the flux set at a value between 5.1.1014 and 1.16.1015 ions / cm2 / s, then the adequate fluence to obtain a micro- or surface nano-structuring of the material is between 2.1016 and 5.5.1016 ions / cm2, in particular between 2.3.1016 and 5.1.1016 ions / cm2.

[0056] Taking into account all of the examples provided above, without consideration of the type of ions envisaged, taking into account the range of fluxes envisaged for the implementation of step (a), namely between 1013 and 1017 ions / cm2 / s, it is noted that the fluence will in all cases be between 1015 and 1020 ions / cm2 when the material is HOPG.

[0057] Furthermore, for all of the examples provided above, it has been observed that the lower the fixed flux, the more the range of adequate values ​​for the fluence moves towards high values, whether for the lower limit or for the upper limit. On the contrary, the higher the fixed flux, the more the range of adequate values ​​for the fluence will move towards low values, whether for the lower limit or for the upper limit.

[0058] This can be generalized to all types of implanted materials.

[0059] The material intended to be micro- or nano-structured can be chosen from: a crystalline or amorphous material (e.g. silicon), a lamellar type material such as highly oriented pyrolytic graphite (HOPG) which is made up of a stack of graphene planes, or a thin-layer material such as zinc oxide (ZnO) on silicon.

[0060] The focused gas ion beam used to perform step (a) is generated with rare gases such as argon or helium or gases capable of chemically reacting with the implanted material such as hydrogen, nitrogen or oxygen.

[0061] Specific examples of tests performed are provided later.

[0062] It is conceivable to provide a step (b) consisting of supplying heat to the level of said localized surface area, concomitantly or subsequently to the localized irradiation step. This supply of heat then aims to enable the material to deform (malleability) under the increase in the local pressure of the implanted gas. This additional energy can be supplied simultaneously or alternately with the ion implantation, it can be of a radiative nature by additional continuous or pulsed beams (ions, photons, electrons) or by localized or non-localized ohmic heating of the sample.

[0063] Furthermore, before implementing step (a), a vacuum pre-implantation step can be provided consisting of irradiating said localized surface area of ​​the material with types of ions other than those used to implement (a). For example, when the material is silicon, the pre-implantation can be carried out with oxygen. Such pre-implantation can in particular make it easier to manage the geometry of the hollow micro- or nano-structure, because this will make it possible to limit the diffusion of the ions subsequently implanted during step (a). Furthermore, this can make it possible to change the properties of the material and therefore its response to implantation during step (a). This can therefore be of interest for managing the geometry of the hollow micro- or nano-structure.

[0064] Alternatively, it may be envisaged that the focused gas ion beam used to implement step (a) comprises at least two different types of ions so as to carry out simultaneous implantation. It is thus possible, for example, to implant oxygen and helium simultaneously.

[0065] In the case of lamellar materials (such as HOPG), the method according to the invention makes it possible to control the exfoliation of the surface by the implantation of ions from the focused gas ion beam. This is also the case by ion pre-implantation combined with the implantation itself (step (a)).

[0066] Furthermore, during step (a), it is possible to scan the surface of the material with the focused gas ion beam. Indeed, as the ions are implanted in the material, a blister forms locally and initially, this blister swells to become the micro- or nano-structure of the desired geometry. By moving the beam relative to the sample or vice versa, it is possible to create micro- or nano-structures with much more varied geometries. Thus, localized implantation without scanning typically makes it possible to create a hollow micro- or nanostructure of spheroidal or hemispherical shape on the surface of the material, with diffusion taking place in the same way in all directions. The implementation of scanning will make it possible to generate other shapes, for example lines or others.

[0067] Such scanning may also take place during the pre-implantation step. In this case, the scanning carried out during step (a) is the same as that carried out during the pre-implantation step.

[0068] [Fig. 1] is a representative diagram of a device D, used to implement the method according to the invention.

[0069] This device D comprises a source of gaseous element ions 10 connected to a focused ion beam column 20 allowing the positioning and shaping of the focused gas ion beam. It is therefore the components 10, 20 which make it possible to obtain the ion beam.

[0070] The device D also comprises a positioning table 30, advantageously multi-axis. This makes it possible to position an ECH sample of the material that one seeks to structure on the surface. This positioning can be both in location according to the different directions X, YZ of the space of an orthogonal reference but also at an angle relative to the direction of propagation of the focused ion beam.

[0071] The device D may optionally provide a localized heating means 40 which may come from ions, electrons or photons (e.g. laser), supplied continuously or pulsed.

[0072] Finally, the device D may comprise display means. Thus, it is possible consider a scanning electron microscope SEM allowing the observation of the structures obtained on the surface of the material (sample). The device D may also include a secondary electron detector 50 in order to carry out ion and electron imaging if necessary.

[0073] All of the aforementioned means open into or are located in a vacuum chamber designated by the dotted lines. Examples

[0074] All the following examples were carried out “under vacuum” and more precisely at around 108 mbar.

[0075] A first test was carried out with device D (experimental installation) described previously in crystalline silicon with a localized implantation of helium at 20 keV.

[0076] [Fig.2a] shows the results of the implantation visualized with a scanning electron microscope (SEM). In this [Fig.2a], we note the presence of a small blister and a larger blister, in turn obtained from a small blister and a disk-shaped scan to enlarge the diameter of the small blister.

[0077] [Fig.2b] is an enlarged sectional view of the large blister of [Fig.2a]. It can be seen in this [Fig.2b] that the blister has a hollow structure.

[0078] From there, the conditions under which such a hollow structure can be obtained on the surface of a material have been specified.

[0079] The method according to the invention was carried out on HOPG under the following conditions: - oxygen implantation with a kinetic energy of 20keV, - constant flux of 9.1014 ions / cm2 / s, - for different values ​​of fluence.

[0080] Figures 3a, 3b and 3c show images obtained using a scanning electron microscope (SEM) for respective fluences of 2.6.1016 ions / cm2 ([Fig.3a]) where no structuring of the surface is observed (no blister), 3.3.1016 ions / cm2 ([Fig.3b]) where the presence of a blister (hollow structure in this case) is observed and 1017 ions / cm2 ([Fig.3c]) where it is observed that the blister has disappeared, the surface, degraded, is no longer structured.

[0081] Here, we therefore illustrate a value of the adequate fluence ([Fig.3b]) once the other parameters are given (type of ions and kinetic energy given, fixed flux, material = HOPG).

[0082] The method according to the invention was then carried out still in HOPG under the following conditions: - oxygen implantation at 10keV, - constant flux of 2.19.1014 ions / cm2 / s, and - variable influence.

[0083] [Fig.4] shows an image taken with a scanning electron microscope (SEM) for the following fluences (from left to right): 2.19.1014, 2.19.1015, 4.38.1015, 1.09.1016, 1.75.1016, 2.39.1016, 4.38.1016, 6.57.1016 and 1.09.1017 ions / cm2.

[0084] In all cases, [Fig. 4] shows that there is no appearance of blisters (in this case hollow structures). Each time, a surface defect is obtained which cannot be described as surface structuring (uncontrolled). Increasing the fluence beyond the highest fluence value tested would not allow controlled structuring of the surface of the material (in particular a hollow structure) to be obtained. This is to be compared with the results presented in support of [Fig. 3b] where the kinetic energy, fixed at 20keV, is sufficient to generate said blisters for certain flux and fluence conditions.

[0085] The method according to the invention was then carried out still in HOPG under the following conditions: - implantation of oxygen at 40keV, - constant flux fixed either at 7.8.1014 ions / cm2 / s ([Fig.5a]), or at 3.07.1014 ions / cm2 / s ([Fig.5b]), and - variable fluence for a given flux: from 4.68.1016 to 6.63.1016 ions / cm2 in steps of 0.325.1016 ions / cm2 in [Fig.5a] and 1.04.1017 and 1.23.1017 ions / cm2 in [Fig.5b].

[0086] In all the test conditions mentioned above, blisters (in this case hollow structures) are visualized. However, it can be seen in [Fig.5a] that the blisters begin to deteriorate from a fluence of approximately 6.1016ions / cm2. It can be seen in [Fig.5b] that the blisters have larger dimensions than those in [Fig.5a] (the scale is the same in both figures), which shows that it is possible with a lower flux to have higher fluences to make the blisters grow without them degrading.

[0087] Then, the method according to the invention was implemented on crystalline silicon under the following conditions: - helium implantation with a kinetic energy of 10 keV ([Fig.6a]), - implantation of hydrogen with a kinetic energy of 10 keV ([Fig.6b]),

[0088] in flow and fluence conditions capable of allowing the creation of blisters (in this case hollow structures).

[0089] [Fig.6a] represents the blisters obtained by implanting helium and [Fig.6b] represents the blisters obtained by implanting hydrogen. It is noted that the structures are reproducible in both cases and that the height of the outgrowth is greater in the case of helium compared to the case of hydrogen. This is principally- payment due to the fact that hydrogen is implanted more deeply than helium.

[0090] Further tests were then carried out to show the possibility of achieving different geometric shapes, by scanning the surface of the implanted material.

[0091] Thus, in Figures 7a and 7b, an implantation made in crystalline silicon with helium at 10 keV can be visualized using a scanning electron microscope, of course with the flow and fluence conditions adapted to define blisters (in this case hollow structures), by carrying out different types of scanning. In [Fig.7a], parallel lines are defined (by means of linear scans) whose width does not exceed one micron and about 40 microns in length. In [Fig.7b], a toroidal shape is defined (by means of a circular scan) with an internal “diameter” of approximately between 2.6 and 3 microns and an external diameter of the order of 5 microns.

[0092] Similarly, in Figures 8a and 8b, we can visualize under a scanning electron microscope (SEM) an implantation made with helium at 10 keV in HOPG with a simultaneous implantation ([Fig.8a]) and a pre-implantation ([Fig.8b]) of oxygen at 40 keV, of course with the flow and fluence conditions adapted to define blisters (in this case hollow structures). In [Fig.8a], we observe spheroid shapes of different diameters, some forming hollow nanostructures and others hollow microstructures (the largest spheroid shown has a diameter exceeding one micron). In [Fig.8b], we have a particular spheroid, forming a nanostructure with in this case a diameter of approximately 600nm.We therefore note that carrying out a simultaneous implantation of two different types of ions (in this case oxygen and helium) or a pre-implantation of one type of ion (in this case oxygen) followed by an implantation of another type of ion (in this case helium) all other things being equal results in a different structuring of the surface of the implanted material.

[0093] It should be noted that the structures obtained with the various tests carried out are stable to consider an effective application.

[0094] The invention can find various applications.

[0095] Thus, with HOPG (as a reminder, made up of stacking graphene planes) as implanted material, it is possible to envisage, thanks to the method according to the invention: - an increase in the specific surface area: the fact of controlling the localized exfoliation would make it possible, in the case of lamellar type samples such as HOPG, to increase the specific surface area of ​​the material considered compared to carbon nanospheres while retaining the advantages of a massive sample (no possible dispersion); - sensors and energy conversion: the hollow cells formed by the process according to the invention contain a gas inside which can act on the wall during energy absorption (photons or phonons for example). Since graphene is recognized as a material with piezoelectric properties, the forces induced by the gas on the walls could be measured by this effect.

[0096] Thus also, applications can be foreseen more generally for defining metamaterials, for example to improve the stealth of an aircraft whose external surface would be structured in this way.

Claims

Claims

1. Method for surface micro- or nano-structuring of a material, characterized in that it comprises a step (a) of vacuum irradiation consisting of irradiating a localized surface area of said material with a focused gas ion beam, said beam being defined by: - a kinetic energy of the ions between 5 and 30 keV for hydrogen ions, between 10 and 60 keV for helium ions or between 20 and 500 keV for ions with an atomic mass unit greater than or equal to 12, - a flux fixed at a value between 1013 and 1018 ions / cm2 / s, and - a fluence whose value comes from a database linking the nature of said material, the type of ions used and the associated kinetic energy, and the value of the flux to obtain surface micro- or nanostructuring of the material.

2. Method for surface micro- or nano-structuring of a material according to claim 1, characterized in that it comprises a step (b) consisting of supplying heat to the level of said localized surface zone, concomitantly or subsequently to step (a).

3. Method for surface micro- or nano-structuring of a material according to one of the preceding claims, characterized in that during step (a), the surface of the material is scanned with the focused ion beam.

4. Method for surface micro- or nano-structuring of a material according to one of the preceding claims, characterized in that it comprises, before implementing step (a), a vacuum pre-implantation step consisting of irradiating said localized surface area of the material with types of ions other than those used to implement step (a).

5. Method for surface micro- or nano-structuring of a material according to the preceding claim, characterized in that during the pre-implantation step, the surface of the material is scanned with the focused ion beam, the scanning carried out during step (a) then being the same as that carried out during the pre-implantation.

6. Method for surface micro- or nano-structuring of a material according to one of claims 1 to 3, characterized in that the focused gas ion beam used to implement step (a) comprises at least two different types of ions so as to carry out an implantation simultaneous.

7. Method for surface micro- or nano-structuring of a material according to one of the preceding claims, characterized in that the micro- or nano-structured material is chosen from: a crystalline or amorphous material, a lamellar type material such as highly oriented pyrolytic graphite (HOPG), a thin-layer material such as zinc oxide (ZnO) on silicon.

8. Method for surface micro- or nano-structuring of a material according to one of the preceding claims, characterized in that the focused gas ion beam used to implement step (a) is generated with rare gases, for example argon or helium, or gases capable of reacting chemically with said material, for example hydrogen, nitrogen or oxygen.

9. Method for surface micro- or nano-structuring of a material according to one of the preceding claims, characterized in that the flux is fixed at a value between 1013 and 5.1017 ions / cm2 / s, advantageously between 1013 and 1017 ions / cm2 / s, advantageously between 1013 and 5.1016 ions / cm2 / s, advantageously between 1014 and 5.1016 ions / cm2 / s.

10. Method for surface micro- or nano-structuring of a material according to one of the preceding claims, characterized in that the material being highly oriented pyrolytic graphite (HOPG) and the focused gas ion beam used to implement step (a) being generated with helium, with a flux fixed at a value between 1014 and 6.1016 ions / cm2 / s, the fluence is between 1016 and 1020 ions / cm2, in particular between 2.1016 and 6.1019 ions / cm2.

11. Method for surface micro- or nano-structuring of a material according to one of claims 1 to 9, characterized in that the material is highly oriented pyrolytic graphite (HOPG) and the focused gas ion beam used to implement step (a) is generated with oxygen at a kinetic energy of between 20keV and 40keV, with a flux fixed at a value of between 1013 and 2.5.1015 ions / cm2 / s, the fluence is between 1015 and 5.1017 ions / cm2, in particular between 4.1015 and 1.5.1017 ions / cm2.

12. Method for surface micro- or nano-structuring of a material according to one of claims 1 to 9, characterized in that the material is highly oriented pyrolytic graphite (HOPG) and the focused gas ion beam used to implement step (a) is generated with nitrogen at a kinetic energy of 20keV, with a flux fixed at a value between 9.4.1014 and 1.6.1015 ions / cm2 / s, the fluence is between 6.4.1016 and 1017 ions / cm2.

13. Method for surface micro- or nano-structuring of a material according to one of claims 1 to 9, characterized in that the material being highly oriented pyrolytic graphite (HOPG) and the focused gas ion beam used to implement step (a) being generated with argon at a kinetic energy of 92keV, with a flux fixed at a value between 5.1.1014 and 1.16.1015 ions / cm2 / s, the fluence is between 2.1016 and 5.5.1016 ions / cm2, in particular between 2.3.1016 and 5.1.1016 ions / cm2.

14. Method for surface micro- or nano-structuring of a material according to one of the preceding claims, characterized in that the surface micro- or nano-structuring of the material consists of one or more hollow micro- or nano-structure(s).

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