Patent ID: 12233577

The drawings are given as examples, and are not limiting of the invention. They constitute principle schematic representations intended to facilitate the understanding of the invention and are not necessarily to the scale of practical applications. In particular, the relative dimensions of the masks, layers, layer portions and patterns and openings are not representative of reality.

DETAILED DESCRIPTION OF THE INVENTION

Before starting a detailed review of embodiments of the invention, below optional features are stated, which can optionally be used in association or alternatively.

According to an example, the etching is configured to etch, in the first portion, a first set of patterns and to etch, in the second portion, a second set of patterns:the first set of patterns having a first pattern density D1and a first height H1,the second set of patterns having a second pattern density D2, and a second height H2, and D2>D1and/or H2>H1.

Thus, for a lower pattern density, the height H1is lower than the height of the patterns for a greater pattern density. The adaptation of the height according to the pattern density makes it possible to further improve the homogeneity of the residual resin layer during nanoprinting.

The heights of the etched patterns are measured from the upper face of the layer, and up to a bottom of the patterns. This measurement is preferably taken in a direction perpendicular to a plane, wherein the upper face main extends. Preferably, this direction is parallel to the favoured implantation direction.

According to an example, the etching is configured such that the etching speed at least of the second portion, preferably of the first and second portions, is greater than the etching speed of the third non-implanted portion. Thus, the non-implanted portion forms a braking layer, even a stop layer, of the etching, making it possible to control the height of the etched pattern from the implanted portions.

According to an example, prior to the ion implantation, and preferably before the production of the etching mask, the method comprises the production of a so-called implantation mask on at least one portion of the upper face of the layer, and the ion implantation is at least partially performed through the implantation mask, such that the first implanted portion has a first implantation depth P1and the second implanted portion has a second implantation depth P2, with P2strictly greater than P1and P1, zero or greater than 0.

The implantation mask makes it possible to create a difference of height on the surface of the layer. During the ion implantation, the penetration of the ions into the layer will be impacted by the presence or not of a mask, and the optional variation of thickness of the implantation mask above the layer. According to the implanted location, the ions will therefore progress up to different depths. The depth gradient makes it possible to modulate the etching speeds of the patterns along the normal to the main extension plane of the upper face. For a low implantation depth, the etched patterns have, for example, a lesser height. For a greater implantation depth, the etched patterns have, for example, a greater height.

The implanted depth is measured from the upper face of the layer and in a direction perpendicular to a plane, wherein the upper face mainly extends. Preferably, this direction is parallel to the favoured implantation direction.

According to an example, the mould is called flexible, i.e. that it is deformable under the action of their own weight and/or a pressing force in a resin layer. Typically, for thicknesses going up to a few hundred micrometres and to have a Young's modulus, for example, less than 10 GPa.

According to an example, the implantation mask is configured to only cover a portion of the upper face of the layer.

According to an example, P2is strictly greater than P1, and P1is non-zero. Thus, the entire upper face is implanted, at different depths.

According to an example, P2is strictly greater than P1, and P1is zero. Thus, a fraction of the upper face is not implanted.

According to an example, the implantation mask is configured, so as to have a thickness gradient between at least one first thickness E1and one second thickness E2, with E1strictly greater than E2and E2zero or greater than 0.

Preferably, E2is strictly greater than 0. Thus, the layer is covered by the mask on the surface of its first portion and of its second portion. This improves the quality of the interface between the implantation mask and the substrate after the ion implantation. Indeed, if E2is zero, then the surface of the layer is not protected during the ion implantation, at the surface of the second portion. According to the implantation conditions, it is possible that the properties of the second portion, not protected, are different from those of the first portion protected by the implantation mask. Consequently, different etching behaviours can be had. It is therefore advantageous that the first and second portions are covered by the implantation mask of non-zero thickness, to obtain a surface of homogenous property coming from the implantation.

According to an example, the thickness gradient of the mask between E1and E2is substantially equal to the depth difference between P1and P2.

According to an example, the first thickness E1is substantially between 50 nm and 100 μm. According to an example, the second thickness E2is substantially between 0 nm and E1.

According to an example, the method comprises a removal of the mask after implantation and before the etching step.

According to an example, the ion implantation is configured such that at least the second implantation depth P2, and preferably the first P1and second P2depths, is/are greater than or equal to 30 nm, preferably strictly greater than 30 nm. According to an example, the ion implantation is configured, such that at least one, and preferably each, from among the first and second implantation depths is less than or equal to 1 μm (10−6metres). Preferably, the ion implantation is configured such that at least one, and preferably each, from among the first and second implantation depths is between 30 nm and 1 μm.

The ion implantation can thus be done over a depth substantially equal to the height of the pattern, which will be obtained by etching. This is particularly advantageous to implement a selective etching of the implanted portion with respect to the non-implanted portion. The non-implanted portion under the implanted portion can thus serve as a stop layer during etching.

According to an example, the ion implantation is done by an implanter.

According to an example, the ion implantation is configured, such that the first P1and second P2implantation depths are less than or equal to 30 nm, preferably less than or equal to 10 nm. The ion implantation can thus be done on the surface of the layer. The implanted portions can serve as a braking, or preferably acceleration primer to the etching to manufacture the patterns.

According to an example, the ion implantation is done by a plasma.

According to an example, the implantation mask is configured, such that the first and second portions are spaced apart, in a direction parallel to a main extension plane of the upper face of the layer, of a distance less than or equal to the smallest distance separating two adjacent patterns of different heights. Thus, in a direction parallel to the main extension plane of the upper face, the distance over which the resin thickness varies during the pattern transfer by the mould, is less than or equal to the distance between the patterns of different heights. The resin thickness only varies between two zones where the resin thickness is constant.

According to an example, the thickness gradient of the implantation mask is configured, such that the first and second portions are spaced apart, in a direction parallel to the main extension plane of the upper face of the layer, of a distance less than or equal to the smallest distance separating two adjacent patterns of different heights.

According to an example, the implantation mask is configured such that the first and second portions are separated by an intermediate portion, wherein the implantation depth varies. The intermediate portion thus has a progressive depth gradient between the first and second portions.

According to an example, the thickness gradient of the implantation mask is configured, such that the first and second portions are separated by an intermediate portion, wherein the implantation depth varies.

According to an example, the implantation mask is configured, such that the first and second portions are directly adjacent. The first and second portions thus form a steep depth gradient between P1and P2.

According to an example, the thickness gradient of the implantation mask is configured, such that the first and second portions are directly adjacent.

According to an example, the ion implantation is configured, such that the first and second portions taken together extend over substantially the entire main extension plane of the upper face of the layer.

According to an example, prior to the etching, the method comprises several ion implantations, so as to implant a plurality of first portions and a plurality of second portions, the ion implantations being configured together, such that:the first portions differ from the second portions by at least one of the parameters taken from among: a nature of the implanted ions, a dose of implanted ions, and/orthe first and second portions have implantation depths P1, P2different between the first portions and the second portions.

Thus, the method makes it possible to implant first portions and second portions in the layer, preferably localised. According to the nature of the ion and/or the implantation depth, the etching speed is modulated to obtain patterns of different heights in each of the portions.

According to an example, each implanted portion has one single implantation depth.

According to an example, the implanted portions are separated from one another by the third non-implanted portion.

According to an example, at least one pattern extends into each of the implanted portions.

According to an example, at least one from among the first portion and the second portion, preferably the first portion and the second portion, is/are implanted with an implantation dose substantially between 1012and 1015at/cm2.

According to an example, the ion implantations are configured, such that each of the first and second implanted portions extends, in a direction parallel to the main extension direction of the upper face of the layer, over a distance substantially equal to a dimension of the pattern made during etching, in the same direction.

According to an example, the ion implantations are performed through the etching mask, such that each of the first and second implanted portions extends in line with the openings of the etching mask.

In this direction, the dimensions of an implanted portion coincide with those of the pattern to be etched. The implanted portion thus makes it possible to modulate the properties of the layer to define the contours of the pattern to be etched.

According to an example, the etching is configured to selectively etch each implanted portion, at least the second portion, and if necessary, the first and second portions, with respect to the third non-implanted portion. Thus, during etching, the non-implanted portion forms a stop layer of the etching. The etching step is made more reliable and reproducible, by depending less and preferably by no longer depending on the etching time.

According to an example, the etching is configured such that the etching speed of the implanted portion is at least 100 times greater than the etching speed of the non-implanted portion.

According to an example, the etching is configured so as to not etch the non-implanted portion.

According to an example, the etching is stopped after having consumed the entire thickness of the second portion located in line with the openings of the etching mask. The depth of the patterns is thus controlled with accuracy.

According to an example, the ion implantation is configured to implant at least one from among oxygen, hydrogen, helium, arsenic, phosphor and carbon ions, in the layer.

According to an example, the layer is with the basis or made of at least one from among silicon or a material transparent at a 365 nm wavelength.

According to an example, the method is such that D2>D1 and H2>H1.

According to an example, the method is such that D2>D1 and H2<H1.

According to an example, the layer is made of silicon.

According to an example, the layer is with the basis or made of silicon oxide of formula SiO2, of silicon carbide of formula SiC.

According to an example, the method comprises one single etching step.

According to an example, the mould is a so-called master mould, intended to serve for the production of secondary moulds for nanoprinting.

According to an example, the mould is such that D2>D1 and H2>H1.

According to an example, the mould is such that D2>D1 and H2<H1.

According to an example, the mould is a master mould and the total volume Vb of the hollow zones defined by the second set of patterns is greater than the total volume Va of the hollow zones defined by the first set of patterns.

According to another example, the mould is a “direct” mould, intended to be pressed in a resin without intermediate mould. In this case, the volume Vb of the hollow zones defined by the second set of patterns is less than the total volume Va of the hollow zones defined by the first set of patterns.

According to an example, the implantation is performed in a favoured implantation direction perpendicular to the upper face.

According to an example, in the mould, the first implanted portion has a first implantation depth P1and the second implanted portion has a second implantation depth P2, with P2strictly greater than P1and P1zero or greater than 0.

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According to an example, the layer has, in the first portion, a first set of patterns, and in the second portion, a second set of patterns, such that:the first set of patterns having a first pattern density D1and a first height H1,the second set of patterns having a second pattern density D2, and D2>D1and/or H2>H1.

According to an example, at least one, and preferably each, from among the first and second implantation depths is greater than or equal to 30 nm.

According to an example, at least one, and preferably each, from among the first and second implantation depths is less than or equal to 1 μm.

Preferably, at least one, and preferably each, from among the first and second implantation depths is between 30 nm and 1 μm.

According to an example, the first and second implantation depths are less than or equal to 30 nm, preferably less than or equal to 10 nm.

According to an example, the first and second portions are spaced apart, in a direction parallel to the main extension plane of the upper face of the layer, by a distance less than or equal to the smallest distance separating two adjacent patterns of different heights.

It is specified that in the scope of the present invention, by a substrate or a layer “with the basis” of a species A, this means a substrate or a layer comprising this species A only, or this species A and optionally other species.

A substrate comprising a layer can be:either, preferably, a stack wherein the substrate comprises the layer deposited on a support layer,or a substrate only comprising the layer. In this case, the layer can be self-supporting, i.e. that it supports its own weight.

In the scope of the present invention, a material which makes it possible to transmit at least 70% of a light flow of this given wavelength is qualified as a transparent material with a given wavelength.

Several examples of embodiments of the invention implementing successive steps of the manufacturing method are described below. Unless explicitly mentioned otherwise, the adjective “successive” does not necessarily imply, even if this is generally preferred, that the steps follow one another immediately, intermediate steps being able to separate them.

Moreover, the term “step” means the embodiment of a part of the method, and can reference a set of substeps.

Moreover, the term “step” does not compulsorily mean that the actions carried out during a step are simultaneous or immediately successive. Certain actions of a first step can, in particular, be followed by actions linked to a different step, and other actions of the first step can then be resumed. Thus, the term “step” does not necessarily mean single and inseparable actions over time and in the sequence of the phases of the method.

By microelectronic device, this means any type of device produced with the microelectronic means. These devices comprise, in particular in addition to devices with a purely electronic purpose, micromechanical or electromechanical devices (MEMS, NEMS, etc.) as well as optical or optoelectronic devices (MOEMS, LED, etc.).

This can be a device intended to ensure an electronic, optical, mechanical function, etc. This can also be an intermediate product only intended for the production of another microelectronic device.

It is specified that in the scope of the present invention, the thickness of a layer or of the substrate is measured in a direction perpendicular to the surface, according to which this layer or this substrate has its maximum extension. The thickness is thus taken in a direction perpendicular to the main faces of the layer, or of the substrate on which the different layers rest. In the figures, the thickness is taken along the vertical.

It is specified that, in the scope of the present invention, the terms “on”, “surmounts”, “covers”, “underlying”, “opposite” and their equivalents do not necessarily mean “in contact with”. Thus, for example, the deposition, the transfer, the assembly or the application of a first layer on a second layer, does not compulsorily mean that the two layers are directly in contact with one another, but means that the first layer covers at least partially the second layer, by being either directly in contact with it, or by being separated from it by at least one other layer or at least one other element.

By a parameter “substantially equal to/greater than/less than” a given value, this means that this parameter is equal to/greater than/less than the given value, plus or minus 10%, close to this value. By a parameter “substantially between” two given values, this means that this parameter is, as a minimum, equal to the smallest given value, plus or minus 10%, close to this value, and as a maximum, equal to the greatest given value, plus or minus 10%, close to this value.

In the scope of the present invention, an organic or organo-mineral material being able to be mechanically shaped by pressing by a mould comprising patterns is qualified as a printable resin. A cross-linking or polymerisable resin is a printable resin which has the faculty to cross-link or to polymerise by exposure to a photon beam, for example, in the ultraviolet range and/or by application of a temperature. This type of resin is conventionally used in UV-assisted or thermally-assisted nanometric printing methods.

In the scope of the invention, the energies are given in electronvolts, for which 1 eV=1.602.10−19J, in the international unit system.

Several non-limiting examples of the invention will now be described in detail, in reference toFIGS.2A to7B.

The method comprises the provision of a substrate10comprising a layer11having an upper face110and a lower face115opposite the upper face110. In the figures, it is considered, in a non-limiting manner, that the substrate10is a stack comprising a support layer10a, which can also be referenced support substrate, and the layer11surmounting the support layer10a. It can be provided that the substrate10only comprises the layer11.

The method further comprises an ion implantation, configured such that the layer11has at least one first portion111and at least one second portion112, each of these portions extending from the upper face110. The properties of these portions are different from one another, such that an etching of patterns114a,114bfrom each of these portions111,112gives patterns114a,114bof different heights.

) For this, the ion implantation is configured such that the first portion111is not implanted or has a first implantation different from the second implantation. The second portion112is implanted, and has the second implantation. According to an example, the first implantation and the second implantation differ by, as subsequently described in more detail in reference to the figures:an implantation depth, and/ora nature of the implanted ions, and/ora dose of implanted ions.

For this, the ion implantation parameters can be varied, and for example, the type of implanted ions, the implantation energy and/or the dose of implanted ions, in a known manner for a person skilled in the art. In practice, the ion implantation induced in the implanted material, a lateral extension of the implanted zone through the interactions (elastic and inelastic) between the ions and the implanted material, which is conveyed by the presence of a switch for diffusing the implanted ions, well-known to a person skilled in the art. The geometric shape of this switch, namely the implanted depth and the optional lateral extensions of the latter, depends in particular on:the implantation conditions: atomic number of the implanted ion and of the acceleration voltage in the equipment;the materials of the deposited layers and the substrate used, which will impact the intensities of the interactions between the ions and the implanted materials.

A skilled person can, for example, resort to known tools, such as SRIM (Stopping and Range of Ions in Matter) or TRIM (TRansport of Ions in Matter) which make it possible to simulate the interactions between ions and the material of the layer11.

The ion implantation further defines, in the layer11, a third non-implanted portion11extending at least from the first portion111, and preferably from the first111and second112portions up to the lower face115of the layer11. The third portion113extends more particularly in line with the first portion111only, or in line with of the first111and second112portions. According to an example, the second portion112extends up to the lower face150of the layer11.

Before or after implantation, an etching mask13is made on the upper face110. The etching mask13has a plurality of openings130a,130bfrom which the patterns of the mould1will be formed in the etching step.

After producing the etching mask13and after implantation, the method further comprises an etching of the layer11configured so as to have a different etching speed between at least the second portion112and the third portion113. The etching can be a wet etching or preferably a dry etching, for example a plasma etching or a reactive ion etching (RIE).

According to an example, the etching of the layer11is configured so as to have a different etching speed between the assembly formed by the first111and second112portions, and the third portion113. According to another example, the etching of the layer11is configured so as to have a different etching speed between each from among the first portion111, the second portion112and the third portion113.

The etching is configured to form at least one pattern114aextending into the first portion111and at least one pattern114bextending into the second portion112, from the upper face110. The patterns114a,114bcan extend only into the first portion111and/or second portion112. The patterns114a,114bcan extend respectively into the first111and second portion112, and into the third portion113extending between the first111and/or second portion112and the lower face150of the layer11. The patterns are hollow shapes extending preferably in line with the upper face110, from this face110, etched through the openings130a,130bof the etching mask13. The patterns are formed in line with the walls delimited by the openings130b,130bof the etching mask13.

The different etching speeds make it possible to etch different patterns between the first111and second112portions, and more specifically, patterns of different heights in the layer11, the height being taken from the upper face110, or equivalently from the tops of the patterns114a,114b, to the bottom of the patterns, in a direction perpendicular to the main extension plane of the upper face110. In the figures, the height of the patterns is taken along the vertical.

According to a preferred example, the etching speed of the second portion112is strictly greater than the etching speed of a non-implanted portion of the layer11, and in particular, the third portion113. A non-implanted portion thus forms a braking layer, even a stop layer, of the etching, making it possible to best control the height of the etched patterns114a,114b. According to an example, the etching speed of the assembly formed by the first111and second112portions is strictly greater than the etching speed of the third portion113. According to another example, the etching speed of each from among the first portion111and the second portion112is strictly greater than the etching speed of the third non-implanted portion13, the etching speeds between the first portion111and the second portion112being able to differ.

According to an example, it is sought to etch a first set of patterns114ahaving a first density, and a second set of patterns114bhaving a second density. In the scope of this invention, by the term “density”, this means the surface or the volume occupied by the hollow shapes that the patterns114a,114bconstitute in the layer11, on a given surface taken along a cross-section of the patterns parallel to the upper face110or the lower face of the layer11. A low density corresponds to a set of patterns having a low hollow volume on the given surface. A high density corresponds to a set of patterns having a large hollow volume on a surface of the same dimension. For example, as illustrated byFIGS.4C,5C and6D:compact patterns having a high density, and are therefore spaced apart by a smaller distance Lb,spaced apart patterns have a low density, and are therefore spaced apart by a greater distance La.

It is noted that the density, in this case, means an average density over a given surface. Variations between the distances Laand/or Lbcan be observed one same set of patterns. Ladoes not vary by more than 20% between the patterns114afor the first set. Lbdoes not vary by more than 20% between the patterns114bfor the second set.

During the transfer of the raised parts of the mould1in the layer to be printed to form the patterns, in order to obtain a more homogenous residual resin thickness between the sets of patterns of different densities, the height between the sets of patterns can be varied.

According to an example, the implantation of the first111and second112portions and the etching are configured, such that:the first set of patterns114ahas a first pattern density D1and a first height H1,the second set of patterns114bhas a second pattern density D2, and a second height H2, with D2>D1and/or H2>H1.

H1and H2each mean an average pattern height for the corresponding set. H1does not vary by more than 20% between the patterns114afor the first set. H2does not vary by more than 20% between the patterns114bfor the second set.

For this, the first set of patterns114acan be etched in the first portion(s)111, and the second set of patterns114bcan be etched in the second portion(s)112. The difference of etching speed described above, thus makes it possible to adapt the height of the patterns according to the density of the sets of patterns and thus to further improve the homogeneity of the residual resin layer during nanoprinting with the mould1.

As an example, in the case where the patterns114a,114bare line arrays, the residual resin thickness Hresidualafter printing by the mould, for example, the master mould or a secondary mould made from a master mould, can be expressed thus:

Hresidual=Hinitial-Hmould⁡(n)/(1+L/S)
With:L the width of the lines on the mould,S the width of the spaces on the mould,Hmould (n) the depth of the patterns n of the mould,Hinitial the initial resin thickness.

For two different pattern densities D1, D2, the L/S ratio is different. In order to obtain the same residual resin thickness Hresidualafter printing by the mould, the mould must have two different pattern heights Hmould(1), Hmould(2). The method is therefore implemented such that E1corresponds to Hmould(1), and E2corresponds to Hmould(2).

Each pattern114a,114bfurther has a pattern volume corresponding to the volume of the hollow zone defined by the patterns111a,114bin question in the layer11. Each set of patterns114a,114bhas a total volume Va, Vb respectively, corresponding to the sum of the hollow pattern volumes of the patterns114a,114bconstituting it. The total volume Va, Vb depends on the height H1, H2 and on the density D1, D2 of the patterns114a,114b. Increasing the height H1, H2 or the density D1, D2 of the patterns114a,114bhas the consequence of increasing the volume Va, Vb of the sets of patterns114a,114b.

During the nanoprinting step, the resin volume being able to be collected by a set of patterns114a,114bis equal to the total volume Va, Vb of the latter. Thus, such that the thickness of the residual layer is homogenous, it is necessary that the Va/Vb ratio between the total volumes Va, Vb is correctly defined, and in particular, that it is carefully chosen, if Va>Vb or if Va<Vb. The implantation of the first111and second112portions and the etching are configured such that the values of these total volumes Va, Vb are such that the resin is satisfactorily distributed between the different sets of patterns114a,114b. Naturally, the sizing of Va and of Vb must consider if the manufactured mould is intended to be used for manufacturing a secondary mould, or if it is intended to directly print a resin.

Following the etching, the method can comprise the removal of the etching mask13to obtain the mould1. The method can comprise, before the removal of the etching mask13, a preliminary thermal treatment step for the compatibility of the materials with the removal step.

It is therefore understood that the mould1comprises, in the layer11carrying the patterns114a,114bintended to be printed in a layer to be structured on a distinct substrate, at least one first non-implanted portion111or having a first implantation, and at least one second portion112having a second implantation different from the first implantation. The first111and second112portions each extending from said upper face110. The layer further comprises a third non-implanted portion113extending at least from the first portion111, and preferably from the first111and second112portions, to the lower face115of the layer10. The features relative to the mould manufacturing method are described. These features can absolutely be transposed to the mould1.

Preferably, the mould1is a master mould intended to perform a nanoprinting of patterns by indirect replication. However, it can be provided that the mould1is used for nanoprinting by direct replication.

The ion implantation can be configured to implant at least one from among oxygen, hydrogen, helium, arsenic, phosphor, zinc and carbon ions, in the layer11. The ion implantation of these ions, as well as the parameters for this, is known by a person skilled in the art. For example, reference can be made toFIGS.7A and7B, representing ion implantation diagrams respectively in silica SiO2and in a photo-resin, available in literature for numerous ions and different materials. These diagrams represent, in a solid line, the distance travelled5(in angstrom Å 10−10m) in the matter by the ions, according to the implantation energy6(in keV, that is 103eV), with, in a dotted line, the distribution range of the distance travelled by the ions during the implantation7(commonly referenced by the symbol σ), according to the implantation energy6(in keV, that is 103eV). InFIG.7A, the illustrated ions are boron B, phosphor P and arsenic As ions. InFIG.7B, the illustrated ions are boron B, silicon Si, hydrogen H and phosphor P ions. A person skilled in the art, upon reading such diagrams, will know which parameters, and in particular, which implantation energy to use to adapt the depths P1and P2.

According to an example, the layer11is with the basis of or made of silicon and/or a material transparent at a 365 nm wavelength. According to an example, the layer is made of silicon. Concerning materials transparent at a 365 nm wavelength, according to an example, the layer is with the basis of or made of silicon oxide of formula SiO2, silicon carbide of formula SiC, preferably the layer thus has a thickness less than or equal to 100 μm. According to another example, the layer is with the basis of or made of silicon nitride of formula Si3N4, preferably the layer thus has a thickness less than or equal to 10 nm.

The implantation mask12can be with the basis of or made of a lithography resin. The implantation mask can comprise a sublayer at the interface between the resin and the upper face110, called partial transmission mask with the basis of or made of titanium nitride of formula TiN or silicon nitride of formula Si3N4. The etching mask13can be with the basis of or made of the same materials as the implantation mask12.

Particular Examples of Embodiments of the Method

Particular examples of embodiments of the method are now described.

According to an example illustrated byFIGS.2A to5C, the method can comprise the production of an implantation mask12on at least one portion110aof the upper face10of the layer11. As illustrated, for example byFIGS.2A and2B, the production of the implantation mask12can be configured, such that the implantation mask12has a thickness gradient between at least one first thickness E1and one second thickness E2, with E1strictly greater than E2and E2zero or strictly greater than 0. The implantation mask12thus creates a thickness differential above the layer11. InFIGS.2A and2B, the example is illustrated in a non-limiting manner, according to which the thickness E2is non-zero.

The ion implantation can be performed through the implantation mask12. Thanks to the thickness differential of the implantation mask12, the first implanted portion111can have a first implantation depth P1and the second implanted portion112can have a second implantation depth P2, with P2strictly greater than P1and P1zero or greater than 0. The path of the ions is considered in a favoured direction perpendicular to the main extension plane of the upper face110of the layer11.

According to the example illustrated byFIGS.3A and3B, P2>P1>0. Thus, the first portion111is implanted up to the first depth P1, and the second portion112is implanted up to the second depth P2. The third portion113can extend from the first depth P1, and preferably from the first and second depths P1, P2, up to the lower face150of the layer11. According to an example, the entire upper face110of the layer11is implanted, at different depths.

For this, the ion implantation can be configured to implant the layer11through the implantation mask12such that the implanted ions pass through the implantation mask12and penetrate into the layer11, over a distance greater than E1and E2taken perpendicularly to the upper face110of the layer11.

The ion implantation can, for this, be configured such that at least one, and preferably each, from among the first P1and second P2implantation depths is greater than 30 nm, and preferably less than 1 μm. The distance travelled by the ions following their penetration into the implantation mask12can be greater than 30 nm, and preferably less than 1 μm. The ion implantation can more specifically be performed by an implanter device, in a known manner by a person skilled in the art.

According to the example illustrated byFIG.3C, P2>P1and P1=0 with respect to the upper face110of the layer11. Thus, the first portion111has a zero implantation depth P1at the layer11. The first portion111is therefore not implanted in the layer11and can be combined with the third non-implanted portion113. The second portion112is implanted up to the second non-zero depth P2in the layer11. The third portion113can extend from the second depth P2, to the lower face150of the layer11. Thus, a fraction of the upper face110is not implanted.

For this, the ion implantation can be configured to implant the layer11through the implantation mask12, such that the implanted ions pass through the implantation mask12over a distance less than E1and do not penetrate into the layer11at the first portion111. According to this example, the implanted ions pass through the implantation mask12over a distance greater than E2and penetrate into the layer11at the second portion112.

The ion implantation can, for this, be configured so as the first P1and second P2implantation depths are less than 30 nm, preferably less than 10 nm. The distance travelled by the ions following their penetration into the implantation mask12can be less than 30 nm, preferably less than 10 nm. The ion implantation can more specifically be performed by a plasma, and in particular by immersion of the substrate10in a plasma, in a known manner by a person skilled in the art.

According to an example, the first thickness E1is substantially between 50 nm and 100 μm. According to an example, the second thickness E2is substantially between 0 nm and E1. These dimensions are, in particular, chosen according to the design of the mould and to the targeted application. According to an example, the thickness gradient of the mask is substantially equal to the depth difference between P1and P2.

The implantation mask12, to have this thickness gradient, can, for example, be performed by greyscale lithography, or alternative methods, like near-field lithography, for example by NanoFrazor™ equipment, and the associated method. Choosing the suitable technology will depend on the tolerances over the distance L0which separates the sets of patterns of different heights, in a direction parallel to the main extension plane of the upper face110.

According to an example, the implantation mask12is configured, such that the first111and second112portions are spaced apart, in a direction parallel to the main extension plane of the upper face110, by a distance L0less than the smallest distance L1separating two adjacent patterns114a,114bof different heights, and more specifically, separating a first set of patterns114aand a second set of patterns114b, as illustrated inFIGS.3A to3C, compared withFIGS.4C and5C.

As illustrated byFIG.3B, the implantation mask12can have a progressive thickness gradient between E1and E2, over the length L0. It is noted that E2can be zero, the implantation mask12only covering a fraction110aof the upper face110, or be strictly greater than 0. Following the ion implantation, the first111and second112portions can thus be separated by an intermediate portion116, in a direction parallel to the main extension plane of the upper face110. In this intermediate portion116, the implantation depth can vary between P1and P2to form a progressive depth gradient. It is noted that it can be provided that P1is zero, or strictly greater than 0 as illustrated, according to the examples described above. Preferably, L0is substantially less than or equal to the smallest distance separating the first and second portions. As illustrated byFIGS.3A and3C, the implantation mask12can have a sharp thickness gradient between E1and E2, over a length L0for example, substantially less than or equal to the smallest distance separating the first and second portions. It is noted that, in this case also, E2can be zero or be strictly greater than 0. Following the ion implantation, the first111and second112portions can thus be directly adjacent in a direction parallel to the main extension plane of the upper face110.

According to an example, the method comprises a removal of the implantation mask12after implantation and before the etching step, preferably before the production of the etching mask13.

According to an example, the etching mask13is produced after the ion implantation, as illustrated, for example, by passing fromFIGS.3A and3CtoFIGS.4A and5A. During the etching, the implanted portions of the layer11preferably have a greater etching speed than the non-implanted portions.

As illustrated, for example, byFIGS.4A and5A, the etching mask13can have openings130aand130bdelimiting the openings corresponding to the patterns114aand114bto be etched in the layer11. A distance L1can separate the set of patterns114aand the set of patterns114b, of different pattern densities, for example symbolised by the lengths Laand Lb. The difference of etching speed between the implanted portions and the non-implanted portions leads to the etching of patterns114a,114bof different heights, as illustrated byFIGS.4B and5B. Following the etching, the method can comprise the removal of the etching mask13, to obtain the mould1illustrated byFIGS.4C and5C.

An example of etching is now described in reference toFIGS.4A to4C. The etching can be performed over an etching duration, chosen such that the entire thickness of the second portion112is consumed in line with the openings130bof the etching mask13, preferably without consuming the third portion113. The first portion111having a depth P1less than the depth P2of the second portion112, and the third portion113having a less etching speed, the height of the patterns114awill be less than the height of the patterns114bin the second portion112. The depth of the patterns is thus controlled with accuracy with the etching time.

According to an example, the etching is configured to selectively etch each implanted portion with respect to the third non-implanted portion113. The etching can be configured, such that the entire thickness of the first111and second112portions is consumed in line with the openings130bof the etching mask13. Thus, the non-implanted portion113forms a stop layer of the etching. Only the first111and second112portions are etched significantly, which enables a controlled stopping of the etching. Controlling the depth of the patterns114a,114bis thus also improved.

An example of etching is now described in reference toFIGS.5A to5C. The second portion112can have an etching speed greater than that of the third portion113. The etching can be performed over an etching duration, chosen such that the entire thickness of the second portion112is consumed in line with the openings130bof the etching mask13, as well as a part of the third portion113. The second portion112being consumed more rapidly, a height differential can be obtained between the patterns114aof height H1and the patterns114bof height H2for one same etching time, as illustrated byFIG.5B. It is noted that it can be provided that the second portion112has an etching speed less than that of the third portion113, the height differential thus being reversed.

Another example of an embodiment of the method is now described in reference toFIGS.6A to6D. The method can comprise several ion implantations, so as to implant a plurality of first portions111and a plurality of second portions112. Each implanted portion can be separated from the adjacent implanted portion by a third non-implanted portion113. The ion implantations are thus performed in a localised manner in the layer11.

For this, the method can comprise the production of the etching mask13, the etching mask having the openings130a,130bcorresponding to the patterns114a,114bto be etched. The ion implantation can be performed through the etching mask13and be configured, such that the implanted portions111,112extend into the layer11in line with the openings130a,130b. Each of the first and second implanted portions111,112can extend, in a direction parallel to the main extension direction of the upper face110, over a distance L3, L4substantially equal to a dimension L3, L4of the corresponding pattern114a,114bproduced during the etching, in the same direction. The lengths L3, L4are preferably substantially equal to the distance between the walls delimiting the openings130a,130b, in this direction.

The ion implantations can be configured together, such that the first portions111differ from the second portions112by:their implantation depths P1, P2, as for example illustrated byFIG.6A, and/ora nature of the implanted ions, and/or a dose of implanted ions, as for example illustrated byFIG.6B.

The first portions111can correspond to the first set of patterns114adescribed above. The second portions112can correspond to the second set of patterns114bdescribed above.

The ion implantations can be performed by an implanter. The implanter can comprise movable blades4, so as to mask a part of the etching mask13. During a first ion implantation, the blade4can mask the openings130bso as to only implant the first portions111. During a second ion implantation, the blade4can mask the openings130aso as to only implant the second portions112. Thus, the portions111,112can be successively implanted without requiring multiple steps of depositing an etching mask13and15implantations for each type of implanted portions.

As illustrated byFIG.6A, the first portions111can differ from the second portions112by their implantation depth, with P1<P2. The etching can be performed over an etching duration, such that the entire thickness of the second portions112is consumed in line with the openings130bof the etching mask13, preferably without consuming the third portion113. The first portions111having a depth P1 less than the depth P2 of the second portion112, the height of the patterns114awill be less than the height of the patterns114bin the second portions112. The depth of the patterns is thus controlled with accuracy with the etching time.

According to a preferred example, the etching is configured to selectively etch each implanted portion111,112with respect to the third non-implanted portion113. The etching can be configured, such that the entire thickness of the first111and second112portion11is consumed in line with the openings130bof the etching mask13. Thus, the non-implanted portion113forms a stop layer of the etching. Only the first111and second112portions are etched significantly, which enables a controlled stopping of the etching. This can, as an example, be illustrated in passing fromFIG.6AtoFIG.6C. Controlling the depth of the patterns114a,114bis thus further improved.

As illustrated byFIG.6B, the first portions111can differ from the second portions112by the nature of the implanted ions and/or the implanted dose, for one same depth P1 as illustrated or of different implantation depths. The etching can be performed over an etching duration chosen such that the entire thickness of the second portions112is consumed in line with the openings130bof the etching mask13, and consume at least one part of the third portion113. The first portions111can have an etching speed less than that of the second portions112. With the second portions112being consumed more rapidly, a height differential can be obtained between the patterns114aof height H1and the patterns114bof height H2for one same etching time, as illustrated by passing fromFIG.6BtoFIG.6C. It is noted that it can be provided that the second portions112have an etching speed less than that of the first portions111, the height differential thus being reversed.

As indicated above and illustrated by passing fromFIG.6CtoFIG.6D, the etching mask13can be removed after the production of the patterns114aand114b.

FIG.6Dquite specifically illustrates a mould1intended to serve as a master mould in a nanoprinting method. As illustrated inFIG.6E, it can indeed serve to make a secondary mould200having reversed patterns, which themselves will be printed in the resin to be structured. InFIG.6E, the master mould1is represented under the secondary mould200for clarity and homogeneity with the preceding figures. Naturally, in the scope of producing a secondary mould200, during the pressing step, the master mould1can be placed above a deformable layer, intended to form the secondary mould200and pressed in the latter. In this application, the dimensions of the openings130ain the etching mask and the implantation parameters, in particular, will be chosen such that the total volume Vb of the hollow zones defined by the second set of patterns114bis greater than the total volume Va of the hollow zones defined by the first set of patterns114a. Va being the surface occupied by the cavities of the patterns114aof the first set, surface taken in a horizontal plane inFIGS.6A to6E, and Vb being the surface occupied by the cavities of the patterns114bof the second set, surface taken in a horizontal plane inFIGS.6A to6E. Preferably, the density of the second set of patterns114bis such that D2>D1, with, as a condition on the height of the patterns, preferably H2>H1 or H2<H1 such that Vb>Va. It can also be provided that D2<D1 and H2>H1 as long as Vb>Va. The dimensions D1, D2, H1 and H2 being taken on the master mould1. In this way, as represented inFIG.6F, during the nanoprinting of the secondary mould200in a resin layer, the resin is distributed such that the residual layer30′ has a homogenous thickness. This makes it possible to preserve the critical dimensions of the patterns31a′,31b′ during their etching in the substrate3′, or at least limit their degradation (FIG.6G).

The manufacturing method can also be implemented with the aim of manufacturing a so-called direct mould, i.e. intended for a direct replication of the patterns, without passing through a master mould, then a secondary mould. In this scenario, the dimensions of the openings130ain the etching mask and the implantation parameters, in particular, will this time be chosen, such that the total volume Vb of the hollow zones defined by the second set of patterns114bis less than the total volume of the hollow zones Va defined by the first set of patterns114a. For this, D2<D1 can be had, with as a condition on the height of the patterns, H2<H1. D2<D1 and H2>H1 as long as Vb>Va can also be had. It can also be provided that D2>D1 and H2<H1 as long as Vb<Va. The dimensions D1, D2, H1 and H2 being taken on the “direct” single mould, as illustrated inFIG.8A. In this way, there again, a better distribution of the resin and therefore a residual layer30′ of homogenous thickness is obtained during nanoprinting (FIG.8B). As above, the critical dimensions of the patterns31a′,31b′ are preserved or, at least, less degraded than during methods of the prior art (FIG.8C).

Example of a particular implementation of the method by a user

Below, an example of an implementation of the method by a user, in a non-limiting manner, is described.the user chooses the material to be implanted,according to the material chosen, the user selects the ions to be implanted, which:modify the material to be implanted chosen beforehand, andmake it possible to identify an etching chemistry (dry or wet) to selectively etch the implanted portion(s) of the non-implanted material. Experimental tests on solid plates (plates without or with pattern) can be implemented to identify the optimal etching method(s),the implantation conditions are thus determined by simulation according to the desired geometries (for example, depths of the patterns),knowing the ions and the implantation conditions, materials can thus be identified which will serve as a mask and protection for the implantations, in particular materials with a sufficient stopping power,the deposition of the mask and the ion implantation are then performed,the mask can be removed or preserved for a subsequent removal,the selective etching is implemented to form the patterns,if the dimensions of the patterns differ from the targeted dimensions, then a correction on the patterns can be made to adjust these dimensions, for example, by optical proximity correction (OPC).

In view of the description above, it clearly appears that the invention proposes a manufacturing method, making it possible to improve the manufacture of a mould for nanoprinting to control the residual resin thickness, as well as a mould improving the control of the residual resin thickness.

The invention is not limited to the embodiments described above and extends to all the embodiments covered by the invention. The present invention is not limited to the examples described above. Plenty of other variants of embodiments are possible, for example, by combining features described above, without moving away from the scope of the invention. Furthermore, the features described relating to an aspect of the invention can be combined with another aspect of the invention. The mould can have any feature resulting from the implementation of a feature of the method and conversely, the method can comprise any step making it possible to obtain a feature of the mould.