EP3181235A1 - Method for monitoring the divergence of a particle beam under vacuum with an aerodynamic lens and associated aerodynamic lens - Google Patents

Abstract

The invention relates to a method for controlling the divergence of a vacuum particle jet with an aerodynamic lens, said aerodynamic lens (100) comprising: at least one chamber (10 to 14); a diaphragm, referred to as an inlet diaphragm (20), for forming an aerodynamic lens inlet for a particle jet, said inlet diaphragm having a given diameter (d 1); and another diaphragm, called the output diaphragm (25), intended to form an aerodynamic lens output for this particle jet; said method comprising: a step of generating the jet of particles from the inlet to the outlet, under vacuum, of the aerodynamic lens (100); and a step of adjusting the diameter of the outlet diaphragm to control the divergence of the particle jet.

Description

The invention relates to the field of aerodynamic lenses.

An aerodynamic lens is used to generate a jet of particles, in particular nanoparticles, under vacuum.

The generation of this particle stream can be used to achieve the deposition of these particles, under vacuum, on a target surface. In this case, the aerodynamic lens is for example coupled to a physical deposition device under vacuum, comprising the target surface. For example, we can refer to documents FR 2 971 518 and FR 2,994,443 .

The main advantage of an aerodynamic lens is to obtain, at the output thereof, a particle jet, under vacuum, collimated. A collimated particle jet is a particularly narrow jet, so little divergent and dense and which, moreover, is able to maintain these properties over a long distance under vacuum. These properties are advantageous for depositing these particles, under vacuum, on a target surface.

The figure 1 represents a known aerodynamic lens ( Liu et al., "Generating particles Beams of Controlled Dimensions and Divergence: II. Experimental Evaluation of Particle Motion in Aerodynamic Lenses and Nozzle Expansions ", Aerosol. Sci. Technolg., 1995, vol. 22, pp. 314-324 ), particularly well suited to obtain a jet of particles, in particular nanoparticles, collimated at the output of this lens.

This aerodynamic lens LA has a cylindrical shape, whose external diameter is about 10 mm (internal diameter Di = 10 mm, to which the wall thicknesses of the aerodynamic lens must be added to be exact) and the total length L _T d about 300mm.

It comprises several chambers and several diaphragms, in this case five chambers CH1, CH2, CH3, CH4 and CH5 and six diaphragms DPH1 (entry E of the aerodynamic lens defined by the flow direction F of the particle jet, in use) , DPH2, DPH3, DPH4, DPH5 and DPH6 (S output of the aerodynamic lens).

Diaphragms DPH1, DPH2, DPH3, DPH4, DPH5 all have a passage orifice for the particle jet which has a regular cylinder shape, so a constant circular section. However, the diameter of each diaphragm (= diameter of each orifice) decreases from the inlet E to the outlet S of the aerodynamic lens. More precisely, the diameter of the diaphragm DPH1 is 5mm, that of the diaphragm DPH2 is 4.75mm, that of the diaphragm DPH3 is 4.5mm, that of the diaphragm DPH4 is 4.25mm and that of the diaphragm DPH5 is 4mm.

As for the diaphragm DPH6, it has a frustoconical orifice, so a circular section whose diameter evolves according to its thickness, its diameter being greater at its inlet than at its outlet (convergent shape in the direction flow F of the particle jet), which output merges with that of the aerodynamic lens. The diameter of the diaphragm DPH6 at the output S of the aerodynamic lens is smaller than that of the other diaphragms, and in particular that of the diaphragm DPH5, and is 3 mm.

The diaphragms DPH1, DPH5 and DPH6 have a thickness of 10mm (they can also be likened to tubes). The diaphragms DPH2, DPH3 and DPH4 have a thickness not exceeding one millimeter.

All rooms are cylindrical and have a diameter Di identical, 10mm each. Chambers CH1 to CH4 all have the same length L1, of 50mm, and the last chamber CH5 has a length L2, greater than the length L1, of 65mm.

In use, particles in a carrier gas are first provided with means, for example by an aerosol generator, known to those skilled in the art.

A pressure differential is maintained between the input E and the output S of the aerodynamic lens LA, the output S being under vacuum (0.1mbar, for example). Typically, the inlet pressure E of the aerodynamic lens is a few mbar. This pressure differential then makes it possible to generate the jet J of particles under vacuum from the particles in the carrier gas at the inlet of the aerodynamic lens. More specifically, under the effect of this pressure differential, the particles in the carrier gas are caused to form a stream of particles passing successively in the different chambers CH1 to CH5, through the different diaphragms DPH1 to DPH6. At each passage through a diaphragm, the jet of particles is a little more collimated.

It should be noted that the ability of an aerodynamic lens to achieve a collimated particle jet depends on the type of particles that are sought to collimate, and more precisely on their size and density.

In addition, obtaining a collimated jet is not the only design constraint.

Indeed, the aerodynamic lens must have a significant transmission. The transmission of an aerodynamic lens represents the ratio between the number of particles leaving the lens and the number of particles entering this lens. It is sometimes expressed as a percentage.

When the jet of particles passes through a diaphragm, some particles impact the walls of the diaphragm and are not transmitted to the next chamber.

For this reason, it is preferable to provide several rooms that allow collimation in stages. On the figure 1 the diaphragms have diameters smaller and smaller since the entry of the aerodynamic lens to the exit of this lens. However, this is not necessarily the case.

Moreover, the transmission, just like collimation, depends on the type of particles and more particularly on their diameter and their density (or density, which amounts to the same).

Thus, in the case of particles that are too large and / or too dense, the particles may have difficulty following changes in the direction of the flow of the carrier gas. This ability of the jet particles to follow the flow of the carrier gas is more generally defined by the number of Stokes (unsized number, theory of similarity).

Où:

• ρ_p est la masse volumique d'une particule,
• d_p est la taille d'une particule,
• v est la vitesse du gaz porteur,
• µ est la viscosité dynamique du gaz porteur, et
• L_c est une longueur caractéristique.

The number of Stokes is defined by the following relation: $$\mathit{St}=\frac{{\rho }_{p}v{d}_p^2}{\mu {\mathrm{The}}_{\mathrm{VS}}}$$

Or:

• ρ _p is the density of a particle,
• d _p is the size of a particle,
• v is the speed of the carrier gas,
• μ is the dynamic viscosity of the carrier gas, and
• L _c is a characteristic length.

This characteristic length L _c is to be adapted according to the case concerned. For example, if we consider the aerodynamic lens represented on the figure 1 this characteristic length can be chosen as being the difference between the internal radius Ri of the aerodynamic lens (Ri = Di / 2 = 5mm) at which the mean radius Rm of the different diaphragms is removed (Rm = (5 + 4.75 + 4 , 5 + 4.25 + 4 + 3) / (6 * 2) ≅ 2 mm), ie L _c = Ri - Rm ≅ 3mm. Another choice could be made to define this characteristic length.

Thus, if the number of Stokes is too high (particle size too large and / or too dense, for example), the particles can not follow the changes of direction of the carrier gas at the passage of a diaphragm (inertia) and come impact the wall of a diaphragm, which results in a loss of transmission.

Moreover, in the case of small particles and / or small sizes, and even if, consequently, the number of Stokes is small and that the particles can, aerodynamically, follow the changes of direction of the carrier gas in the passage of a diaphragm, the existence of a Brownian motion limits the transmission through a diaphragm.

Thus, the aerodynamic lens represented on the figure 1 , particularly powerful, allows to collimate particles by forming a jet whose diameter is less than 1 mm and a transmission close to unity (100%), for a particle size between 70nm and 500nm.

More generally, an aerodynamic lens generally makes it possible to obtain good collimation of the particles with an acceptable transmission, for particles whose size is between 50 nm and 1 micron.

Indeed, an aerodynamic lens is dimensioned to collimate as much as possible the particle jet at the output of the lens, so as to limit as much as possible the divergence of the particle jet at this output, with the highest transmission possible. This then implies, given the constraints mentioned above, to define a range for the particle size that achieves this goal.

For this purpose, it has already been proposed different aerodynamic lenses than the one shown on the figure 1 .

Thus, depending on the size of the targeted particles, while maintaining collimation and quality transmission, it can provide a number of chambers, and therefore diaphragms, different from that which is represented on the figure 1 .

We can still adapt the geometry of the different chambers (diameter, length of each chamber) and / or those of the different diaphragms.

The design of the aerodynamic lens is thus defined and fixed on this basis and this design makes it possible to implement a method of generating a collimated particle jet as much as possible, that is to say as little divergent as possible.

For the application to vacuum deposition of particles on a target surface, this allows to obtain a narrow deposit, with a Lorentzian profile, on a small surface area (typically less than 1 mm ² ).

An object of the invention is to provide a method for generating a particle jet, under vacuum, based on the use of an aerodynamic lens, according to a different approach of the prior art.

Indeed, the applicant realized that it was possible to control the divergence of the jet of particles at the exit of the aerodynamic lens.

• n chambres, avec n ≥ 2, lesdites chambres étant séparées l'une de l'autre par un diaphragme non amovible et présentant un diamètre donné, non réglable ;
• un diaphragme, dit diaphragme d'entrée, destiné à former une entrée de la lentille aérodynamique pour un jet de particules, ledit diaphragme d'entrée présentant un diamètre donné ; et
• un autre diaphragme, dit diaphragme de sortie, destiné à former une sortie de la lentille aérodynamique pour ce jet de particules, ledit diaphragme de sortie présentant un diamètre réglable ;

ledit procédé comportant :

• une étape de génération du jet de particules depuis l'entrée vers la sortie, sous vide, de la lentille aéradynamique ; et
• une étape de réglage du diamètre du diaphragme de sortie pour contrôler la divergence du jet de particules.

The invention therefore proposes a method for controlling the divergence of a vacuum particle jet with an aerodynamic lens, said aerodynamic lens comprising:

• n chambers, with n ≥ 2, said chambers being separated from each other by a non-removable diaphragm and having a given, non-adjustable diameter;
• a diaphragm, referred to as the inlet diaphragm, for forming an aerodynamic lens inlet for a particle jet, said inlet diaphragm having a given diameter; and
• another diaphragm, said output diaphragm, for forming an aerodynamic lens output for this particle jet, said output diaphragm having an adjustable diameter;

said method comprising:

• a step of generating the particle jet from the inlet to the outlet, under vacuum, of the aerodynamic lens; and
• a step of adjusting the diameter of the outlet diaphragm to control the divergence of the particle jet.

• on règle le diamètre du diaphragme de sortie dans une gamme de valeurs strictement inférieure au diamètre du diaphragme d'entrée ;
• la lentille aérodynamique comporte n chambres, avec n ≥ 3, et donc n diaphragmes autres que le diaphragme de sortie, deux chambres successives étant séparées l'une de l'autre par un diaphragme non amovible et présentant un diamètre donné, non réglable ;
• le diaphragme d'entrée est non amovible et présente un diamètre non réglable ;
• on règle le diamètre du diaphragme de sortie à une valeur strictement inférieure aux diamètres desdits n diaphragmes autres que le diaphragme de sortie ;
• la pression en entrée de la lentille aérodynamique est comprise entre 2mbar et 5mbar, de préférence entre 3mbar et 5mbar.

This method may also include the following features, taken alone or in combination:

• adjusting the diameter of the outlet diaphragm in a range of values strictly less than the diameter of the inlet diaphragm;
• the aerodynamic lens has n chambers, with n ≥ 3, and therefore n diaphragms other than the output diaphragm, two successive chambers being separated from each other by a non-removable diaphragm and having a given diameter, not adjustable;
• the inlet diaphragm is non-removable and has a non-adjustable diameter;
• the diameter of the outlet diaphragm is set to a value strictly smaller than the diameters of said n diaphragms other than the outlet diaphragm;
• the inlet pressure of the aerodynamic lens is between 2mbar and 5mbar, preferably between 3mbar and 5mbar.

The possibility of controlling the divergence of the jet of particles at the outlet of an aerodynamic lens has, according to the applicant, not been reported to date in the prior art. This is also consistent with the fact that aerodynamic lens designers have always sought to obtain a particle jet as collimated as possible, namely the least divergent possible.

• n chambres, avec n ≥ 2, lesdites chambres étant séparées l'une de l'autre par un diaphragme non amovible et présentant un diamètre donné, non réglable ;
• un diaphragme, dit diaphragme d'entrée, destiné à former une entrée de la lentille aérodynamique pour un jet de particules, ledit diaphragme d'entrée présentant un diamètre donné ; et
• un autre diaphragme, dit diaphragme de sortie, destiné à former une sortie de la lentille aérodynamique pour ce jet de particules ;

caractérisée en ce que le diaphragme de sortie présente un diamètre réglable.The invention therefore also proposes an aerodynamic lens for implementing a method according to the invention, comprising:

• n chambers, with n ≥ 2, said chambers being separated from each other by a non-removable diaphragm and having a given, non-adjustable diameter;
• a diaphragm, referred to as the inlet diaphragm, for forming an aerodynamic lens inlet for a particle jet, said inlet diaphragm having a given diameter; and
• another diaphragm, said output diaphragm, intended to form an output of the aerodynamic lens for this particle jet;

characterized in that the outlet diaphragm has an adjustable diameter.

• elle comporte n chambres, avec n ≥ 3, et donc n diaphragmes autres que le diaphragme de sortie, deux chambres successives étant séparées l'une de l'autre par un diaphragme non amovible et présentant un diamètre donné, non réglable ;
• le nombre n de chambres et donc de diaphragmes autres que le diaphragme de sortie est tel que n ≥ 5 et, par exemple, tel que n ≤ 15, deux chambres successives étant séparées l'une de l'autre par un diaphragme non amovible et présentant un diamètre donné, non réglable ;
• le diaphragme d'entrée est non amovible et présente un diamètre non réglable ;
• le diaphragme de sortie se présente sous la forme d'un iris dont le diamètre est réglable par une molette actionnable manuellement ;
• le diaphragme de sortie se présente sous la forme d'un iris dont le diamètre est réglable par un moteur commandé ;
• le diaphragme d'entrée de la chambre comportant ledit diaphragme de sortie de la lentille aérodynamique présente une épaisseur comprise entre 0,2mm et 5mm.

This aerodynamic lens may comprise at least one of the following features, taken alone or in combination:

• it comprises n chambers, with n ≥ 3, and therefore n diaphragms other than the output diaphragm, two successive chambers being separated from each other by a non-removable diaphragm and having a given diameter, not adjustable;
• the number n of chambers and therefore of diaphragms other than the exit diaphragm is such that n ≥ 5 and, for example, such that n ≤ 15, two successive chambers being separated from each other by a non-removable diaphragm and having a given diameter, not adjustable;
• the inlet diaphragm is non-removable and has a non-adjustable diameter;
• the output diaphragm is in the form of an iris whose diameter is adjustable by a hand-operated knob;
• the output diaphragm is in the form of an iris whose diameter is adjustable by a controlled motor;
• the inlet diaphragm of the chamber comprising said outlet diaphragm of the aerodynamic lens has a thickness between 0.2mm and 5mm.

• o n chambres, avec n ≥ 2, lesdites chambres étant séparées l'une de l'autre par un diaphragme non amovible et présentant un diamètre donné, non réglable ;
• o un diaphragme, dit diaphragme d'entrée, destiné à former une entrée de la lentille aérodynamique pour un jet de particules, ledit diaphragme d'entrée présentant un diamètre donné ; et
• ∘ un autre diaphragme, dit diaphragme de sortie, destiné à former une sortie de la lentille aérodynamique pour ce jet de particules, ledit diaphragme de sortie présentant un diamètre donné ;

caractérisé en ce que le diaphragme de sortie est monté de façon amovible au sein de la lentille aérodynamique et en ce que ledit ensemble comprend, en outre, au moins un diaphragme complémentaire présentant un diamètre différent de celui du diaphragme de sortie, ledit au moins un diaphragme complémentaire étant destiné à être monté de façon amovible dans la lentille aérodynamique en lieu et place dudit diaphragme de sortie.In a variant, the invention also proposes an assembly for implementing a method according to the invention, comprising an aerodynamic lens comprising:

• chambers, with n ≥ 2, said chambers being separated from each other by a non-removable diaphragm and having a given diameter, not adjustable;
• a diaphragm, referred to as an inlet diaphragm, for forming an aerodynamic lens inlet for a particle jet, said inlet diaphragm having a given diameter; and
• Diap another diaphragm, said output diaphragm, for forming an aerodynamic lens output for this particle jet, said output diaphragm having a given diameter;

characterized in that the outlet diaphragm is removably mounted within the aerodynamic lens and in that said assembly further comprises at least one complementary diaphragm having a diameter different from that of the exit diaphragm, said at least one complementary diaphragm being intended to be mounted removably in the aerodynamic lens instead of said outlet diaphragm.

• la lentille aérodynamique comporte n chambres, avec n ≥ 3, et donc n diaphragmes autres que le diaphragme de sortie, deux chambres successives étant séparées l'une de l'autre par un diaphragme non amovible et présentant un diamètre donné, non réglable ;
• le nombre n de chambres et donc de diaphragmes autres que le diaphragme de sortie est tel que n ≥ 5 et, par exemple, tel que n ≤ 15, deux chambres successives étant séparées l'une de l'autre par un diaphragme non amovible et présentant un diamètre donné, non réglable ;
• le diaphragme d'entrée est non amovible et présente un diamètre non réglable ;
• le diaphragme d'entrée de la chambre comportant ledit diaphragme de sortie de la lentille aérodynamique présente une épaisseur comprise entre 0,2mm et 5mm.

This set may comprise at least one of the following features, taken alone or in combination:

• the aerodynamic lens has n chambers, with n ≥ 3, and therefore n diaphragms other than the output diaphragm, two successive chambers being separated from each other by a non-removable diaphragm and having a given diameter, not adjustable;
• the number n of chambers and therefore of diaphragms other than the exit diaphragm is such that n ≥ 5 and, for example, such that n ≤ 15, two successive chambers being separated from each other by a non-removable diaphragm and having a given diameter, not adjustable;
• the inlet diaphragm is non-removable and has a non-adjustable diameter;
• the inlet diaphragm of the chamber comprising said outlet diaphragm of the aerodynamic lens has a thickness between 0.2mm and 5mm.

Incidentally, the fact of being able to control the divergence of the particle jet at the exit of the aerodynamic lens is particularly advantageous for the application to the vacuum deposition of the particles on a large target surface (for example greater than 1 cm ² ). Indeed, this control finally makes it possible to adjust the extent of the deposition surface of the particles on the target surface, while allowing homogeneous deposition on this target surface.

The invention therefore finally proposes the use of an aerodynamic lens as described above or of an assembly as described above for depositing, under vacuum, particles on a target surface.

The target surface may have a surface greater than or equal to cm ² .

• La figure 2 représente une lentille aérodynamique susceptible d'être employée pour mettre en oeuvre le procédé selon l'invention ;
• La figure 3 représente une réalisation possible d'un diaphragme utilisé en sortie de la lentille aérodynamique représentée sur la figure 2 ;
• La figure 4 est un schéma représentatif d'un montage complet pour mettre en oeuvre le procédé selon l'invention ;
• La figure 5, qui comprend les figures 5(a) à 5(c), représente les différentes formes du jet de particules susceptibles d'être obtenue en sortie de la lentille aérodynamique de la figure 2 ;
• La figure 6 fournit des résultats expérimentaux ;
• La figure 7, qui comprend les figures 7(a) à 7(c), fournit des résultats de simulation, pour des conditions de jet de particules collimaté ;
• La figure 8, qui comprend les figures 8(a) à 8(c), fournit des résultats de simulation, pour des conditions de jet de particules divergent ;
• La figure 9, qui comprend les figures 9(a) à 9(c), basé sur des résultats de simulation, fournit l'évolution de la divergence du jet de particules en fonction du diamètre du diaphragme utilisé en sortie de cette lentille ;
• La figure 10, qui comprend les figures 10(a) à 10(c), basé sur des résultats de simulation effectués dans les mêmes conditions que celles aboutissant aux résultats de simulation exposés sur la figure 9, fournit l'évolution de la transmission du jet de particules à travers la lentille aérodynamique en fonction du diamètre du diaphragme utilisé en sortie de cette lentille ;
• La figure 11 présente une autre lentille aérodynamique susceptible d'être utilisée pour mettre en oeuvre le procédé selon l'invention ;
• La figure 12 représente une autre lentille aérodynamique susceptible d'être utilisée pour mettre en oeuvre le procédé selon l'invention, et dans laquelle le diaphragme comporte un moteur commandable par un contrôleur ;
• La figure 13 représente un ensemble susceptible d'être utilisé pour mettre en oeuvre le procédé selon l'invention, comportant une lentille aérodynamique dont le diaphragme de sortie est amovible et un jeu de diaphragmes.

Other objects and advantages of the invention will be described below, in support of the appended figures in which:

• The figure 2 represents an aerodynamic lens that can be used to implement the method according to the invention;
• The figure 3 represents a possible embodiment of a diaphragm used at the output of the aerodynamic lens represented on the figure 2 ;
• The figure 4 is a representative diagram of a complete assembly for implementing the method according to the invention;
• The figure 5 , which includes Figures 5 (a) to 5 (c) , represents the different shapes of the jet of particles that can be obtained at the exit of the aerodynamic lens of the figure 2 ;
• The figure 6 provides experimental results;
• The figure 7 , which includes Figures 7 (a) to 7 (c) , provides simulation results for collimated particle jet conditions;
• The figure 8 , which includes Figures 8 (a) to 8 (c) , provides simulation results, for divergent particle jet conditions;
• The figure 9 , which includes Figures 9 (a) to 9 (c) , based on simulation results, provides the evolution of the divergence of the particle jet as a function of the diameter of the diaphragm used at the output of this lens;
• The figure 10 , which includes Figures 10 (a) to 10 (c) , based on simulation results performed under the same conditions as those resulting in the simulation results presented on the figure 9 , provides the evolution of the transmission of the particle jet through the aerodynamic lens as a function of the diameter of the diaphragm used at the output of this lens;
• The figure 11 has another aerodynamic lens that can be used to implement the method according to the invention;
• The figure 12 represents another aerodynamic lens that can be used to implement the method according to the invention, and wherein the diaphragm comprises a motor controllable by a controller;
• The figure 13 represents an assembly that can be used to implement the method according to the invention, comprising an aerodynamic lens whose output diaphragm is removable and a set of diaphragms.

• n chambres, avec n ≥ 2, lesdites chambres étant séparées l'une de l'autre par un diaphragme non amovible et présentant un diamètre donné, non réglable ;
• un diaphragme, dit diaphragme d'entrée, destiné à former une entrée de la lentille aérodynamique pour un jet de particules, ledit diaphragme d'entrée présentant un diamètre donné ; et
• un autre diaphragme, dit diaphragme de sortie, destiné à former une sortie de la lentille aérodynamique pour ce jet de particules, ledit diaphragme de sortie présentant un diamètre réglable ;

ledit procédé comportant

• une étape de génération du jet de particules depuis l'entrée vers la sortie, sous vide, de la lentille aérodynamique ; et
• une étape de réglage du diamètre du diaphragme de sortie pour contrôler la divergence du jet de particules.

The method according to the invention is a method for controlling the divergence of a vacuum particle jet with an aerodynamic lens, said aerodynamic lens comprising:

• n chambers, with n ≥ 2, said chambers being separated from each other by a non-removable diaphragm and having a given, non-adjustable diameter;
• a diaphragm, referred to as the inlet diaphragm, for forming an aerodynamic lens inlet for a particle jet, said inlet diaphragm having a given diameter; and
• another diaphragm, said output diaphragm, for forming an aerodynamic lens output for this particle jet, said output diaphragm having an adjustable diameter;

said method comprising

• a step of generating the particle jet from the inlet to the vacuum outlet of the aerodynamic lens; and
• a step of adjusting the diameter of the outlet diaphragm to control the divergence of the particle jet.

Note that it is usual in the field of aerodynamic lenses, to assimilate a diaphragm to a membrane or wall having an orifice. On the other hand, when speaking of the diameter of the diaphragm, reference is also customarily made to the diameter of the orifice and not to the diameter of the membrane or wall which comprises this orifice.

This applies to the entire description of the invention which follows, as for the prior art described in support of the figure 1 .

The figure 2 represents an aerodynamic lens 100 that can be used to implement this method.

This aerodynamic lens 100 comprises a plurality of chambers 10, 11, 12, 13, 14, a diaphragm, called the inlet diaphragm 20, intended to form an aerodynamic lens inlet for a particle jet, said inlet diaphragm having a given diameter d1 and another diaphragm, said output diaphragm 25, intended to form an output of the aerodynamic lens for this particle jet.

In this case, the inlet diaphragm is non-removable and has a non-adjustable diameter.

The aerodynamic lens also comprises other diaphragms 21, 22, 23, 24 separating two successive chambers. Each diaphragm 21, 22, 23, 24 (other than the outlet diaphragm 25) is a non-removable diaphragm having a given, non-adjustable diameter.

More generally, the aerodynamic lens 100 of the figure 2 is a lens consistent with that of the figure 1 , except the exit diaphragm 25.

However, in the context of the invention, the outlet diaphragm 25 has a diameter _ds adjustable, which is not the case in the prior art.

It is this adjustment, made at the outlet diaphragm 25, which makes it possible to control the divergence of the particle jet, under vacuum, at the outlet of the aerodynamic lens.

Moreover, the diameter of the outlet diaphragm 25 can be adjusted so that its diameter is smaller or smaller than the diameter of the diaphragms 20 to 24.

The figure 3 represents a concrete embodiment that can be envisaged to obtain an outlet diaphragm 25 whose diameter is adjustable.

In this case, it is an iris diaphragm 25 mounted on a MOL wheel, this wheel being manually operable. The rotation (angle β) of this MOL dial to set the diameter d _s of the output diaphragm 25. This setting of the diameter d _s which ultimately controls the divergence of the particle stream at the output of the aerodynamic lens 100 as will be shown later. In practice, the outlet diaphragm 25 is then mounted inside the aerodynamic lens 100 and the MOL wheel is located outside of this lens to be accessible by an operator. We understand that the object (MOL +25) of the figure 3 therefore belongs to the aerodynamic lens 100.

Of course, to implement the method according to the invention, it is necessary to provide a means 40 for generating the particles in a carrier gas, which will allow, by putting under differential pressure between the output S of the aerodynamic lens 100 and the input E of this aerodynamic lens 100, to generate the particle jet.

The figure 4 is a representative diagram of a possible montage for this purpose.

This means 40 comprises a reservoir 41 which contains a mixture of carrier gas and particles in gaseous suspension. The pressure and the temperature of the gas as well as the concentration of nanoparticles in this gas are adjustable. The reservoir 41 may be a synthesis reactor operating for example by laser pyrolysis, laser ablation, evaporation under vacuum, combustion or be a plasma particle generator. It can also be an aerosol generator formed from a suspension of particles in a liquid prepared in advance or from a dry nanometer powder. It is possible to adapt the pressure in the reservoir 41 to that of the entrance of the lens aerodynamic using a diaphragm or OC critical orifice. It is for example possible to have a reservoir 41 at atmospheric pressure and a pressure of a few millibars at the entrance of the aerodynamic lens by placing a diaphragm of a few hundred micrometers in diameter between the reservoir and the aerodynamic lens.

This means 40 also comprises an expansion chamber 42, under vacuum (0.1mbar for example), in which the carrier gas containing the particles is introduced from the tank 41. The pressure in the expansion chamber 42 is less than the pressure of the reservoir 41. The evacuation of the expansion chamber is ensured by a pumping means 43.

The passage of the tank 41 to the expansion chamber 42 is effected by means of the aerodynamic lens 100, shown in FIG. figure 2 .

On this figure 4 , there is also the presence of a target surface SC for the particles.

The figure 5 , which includes Figures 5 (a) to 5 (c) Represents three possible cases adjusting the diameter _s of the exit aperture 25.

On the Figure 5 (a) , the adjustment is made to have for example d = 3mm. This is a classic situation where the diameter of the output diaphragm is strictly less than that of all the other diaphragms 20 to 24 and the number of Stokes is close to unity, so the transmission is also close to unit. The particle jet is then collimated at the outlet of the aerodynamic lens.

On the Figure 5 (b) , the adjustment is made to have d = 2,4mm. Here again, it is a situation where the diameter of the outlet diaphragm 25 is strictly smaller than that of all the other diaphragms 20 to 24. However, the number of Stokes is forced to a value greater than unit, typically between 2.5 and 3 to force the jet of particles to focus quickly at the exit of the aerodynamic lens and obtain a divergent jet. In this case, this situation results in obtaining a half-angle, called α, of divergence said "negative" (the paths intersect on the axis of propagation AP of the aerodynamic lens, the crossover point being noted C on the Figure 5 (b) ). This situation is not classic.

The divergence half-angle α is defined by the angle formed between the propagation axis AP of the aerodynamic lens and the direction DIR given by the shape of the jet.

On the Figure 5 (c) , the setting is made to have d = 6mm. In this case, the diameter of the outlet diaphragm 25 is strictly greater than that of all the diameters of the diaphragms 20 to 24. Moreover, the number of Stokes is then forced to a value substantially less than unity, which has the consequence of not concentrating the jet of particles on the optical axis of the jet. The jet of particles is then divergent, but with a half-angle α of divergence which is "positive" (the trajectories do not intersect on the propagation axis AP of the aerodynamic lens). This situation is not classic.

The different situations have been highlighted with experimental tests using a vacuum chamber, comprising a target surface and coupled to the aerodynamic lens of the figure 2 .

Particles in a carrier gas (aerosol) are generated with a conventional device located upstream of the aerodynamic lens. In this case, the carrier gas is argon. The pressure is 4mbar at the entrance of the aerodynamic lens and under vacuum (0.1mbar, for example) at the exit of the aerodynamic lens.

The exit of the aerodynamic lens can lead directly into the vacuum chamber comprising the target surface (this is for example what is represented on the figure 4 ). The distance between the exit of the aerodynamic lens and the target surface is set at 200mm.

It should be noted that, alternatively, the exit of the aerodynamic lens could lead to an intermediate chamber, under vacuum, this intermediate chamber opening itself, for example by means of a debarker, in a vacuum deposition chamber having the target surface. This possibility is for example proposed in the document FR 2 971 518 .

At first, gold particles (Au) with an average diameter of 35 nm were considered. These particles are relatively dispersed and therefore do not form aggregates. The output diaphragm 25 was then adjusted ( Figure 2, Figure 3 ) to browse a wide range of values of its diameter.

A photograph of the deposits obtained on the target surface was then made. This is the subject of the figure 6 .

For the value of the diameter d = 3.2mm of the exit diaphragm 25, it can be considered that the particle jet is collimated and that one finds oneself in a conventional situation such that one obtains it with the aerodynamic lens of the prior art ( figure 1 ).

For values of the diaphragm diameter smaller than 3.2 mm, it is observed that the smaller the diameter d decreases, the more the impact surface of the gold particles on the target surface is spread. The jet of particles from the aerodynamic lens is therefore increasingly divergent. For the case where d = 2.6mm, the spread is maximum, the diameter of the zone of impact of gold on the target surface is about 1 cm and the half-angle of divergence is about α = 25mrad (This half angle is then negative).

For values of the diameter d of the diaphragm greater than 3.2 mm and up to 4 mm (last value tested experimentally), there is a progressively weaker spreading of the impact surface of the gold particles on the target surface. and therefore more and more collimation of the particle jet.

Furthermore, in all cases, it is observed that the deposition of the gold particles on the target surface is homogeneous. This is particularly advantageous for homogeneous deposition over large areas, for example to achieve a surface coating. Another test was carried out under the same conditions with silicon particles. These particles had an average diameter of 10 nm, but were in the form of aggregates whose size was between 50 nm and 150 nm.

The same type of observations as those of the figure 6 could be done.

These experimental tests therefore show the possibility of implementing the method of the invention.

• le type (densité) et la taille des particules ;
• le diamètre du diaphragme 25 de sortie de la lentille aérodynamique ; et
• la pression en entrée de la lentille aérodynamique.

Moreover, in addition to these experimental tests, a certain number of numerical simulations have been carried out, on the basis of the aerodynamic lens 100 represented on the figure 2 , in order to better define the various relevant parameters in the implementation of the process according to the invention, among which:

• type (density) and particle size;
• the diameter of the exit diaphragm 25 of the aerodynamic lens; and
• the inlet pressure of the aerodynamic lens.

For this purpose, the software used is Flow EFD V5 from Mentor Graphics. This software is indeed capable of treating two-phase flows (here, a particle / carrier gas aerosol) and compressible. It should be noted, however, that this software does not allow to take into account the random behavior due to the Brownian movement and which induces, in practice, a significant effect on particles smaller than 30nm. The Brownian movement has the effect of making a jet of particles more divergent. Also, in the simulation results presented below, it should be kept in mind that in reality, the jet of particles is then a little more divergent than the jet of particles simulated, and all the more so as the particle size is small.

All calculations were performed with argon (Ar) as the carrier gas for the particles.

First calculations were made with a diameter of the outlet diaphragm of _S = 3.2mm _S = 3.4mm or entered into a pressure of the aerodynamic lens 4mbars and an output of the aerodynamic lens vacuo.

The goal is then to determine the influence of particle type and size. For this purpose, gold particles (Au; density 19.3 g / cm ³ ) with a size of 10 nm, silicon particles (Si, density of 2.33 g / cm ³ ) of size 50 nm and particles of polystyrene (density 1.06 g / cm ³ ) of size 100 nm were simulated.

The results are represented on the figure 7 which includes Figure 7 (a) (Au, 10nm), the Figure 7 (b) (Si, 50nm) and the Figure 7 (c) (polystyrene, 100nm).

All of these figures show that the collimated jet conditions are obtained. As a result, the type and size of the particles do not appear to modify, qualitatively, what has been demonstrated with the experimental tests. Nevertheless, these figures represent the optimal collimation conditions (excellent collimation and number of Stokes close to unity). It is therefore found, quantitatively, that the optimum diameter of the exit diaphragm of the aerodynamic lens depends on the type and size of the particles considered (for gold in 10 nm, it is 3.4 mm, the value being slightly lower in other simulated cases).

This is of real interest because it highlights that with the invention, one can obtain collimation for a broad spectrum of the type and size of the particles considered.

Second calculations were made for the same particles (Au in 10nm, Si in 50nm and polystyrene in 100nm) and a same input pressure of the aerodynamic lens of 4mbars, compared to the conditions of the first calculations.

However, the diameter of the diaphragm 25 has been modified and set at d _S = 2.2 mm, ie at a lower value than for the first calculations.

The results are represented on the figure 8 which includes Figure 8 (a) (Au, 10nm), the figure 8 (b) (Si, 50nm) and the Figure 8 (c) (polystyrene, 100nm).

On all of these Figures 8 (a) to 8 (c) it is found that the jet conditions diverge with a negative half-angle of divergence are obtained. As a result, the type and size of the particles do not qualitatively change what has been demonstrated with the experimental tests.

Nevertheless, these second calculations show that, depending on the type and size of the particles, the half-divergence angle is between 45 mrad and 60 mrad. Thus, it is found, in quantitative terms, that the type and size of the particles considered have an influence on the half-angle of divergence of the particle jet.

It therefore means in return that it is possible with the invention to define a given half-angle of divergence regardless of the type and size of particles, by adjusting the diameter of the exit diaphragm of the aerodynamic lens. Thus, in the case of an application to a particle deposition on a target surface, it is possible to manage the extent of the zone of impact of the particles on the target surface without modifying the distance between the exit diaphragm. of the aerodynamic lens and the target surface. Of course, another option is to modify this distance between the exit diaphragm of the aerodynamic lens and the target surface.

Other simulations were performed to determine, more generally, the evolution of the divergence half-angle as a function of the diameter of the outlet diaphragm. In all cases, the inlet pressure of the aerodynamic lens is maintained at 4mbars, the output of the aerodynamic lens being under vacuum.

The results of these simulations are represented on the figure 9 which includes Figures 9 (a) to 9 (c) . More specifically, the Figure 9 (a) is interested in gold (Au), in sizes between 10nm and 2 microns. The Figure 9 (b) is interested in silicon (Si), according to sizes between 50nm and 2 microns. The Figure 9 (c) is interested in polystyrene, in sizes between 50nm and 2 microns.

Regardless of the type of particles considered, it should firstly be noted that the particles have been simulated over a very wide range of size, enlarged with respect to the size ranges targeted by a prior art aerodynamic lens (by example, figure 1 ) and that these simulations show that the adjustment of the output diaphragm actually makes it possible to control the divergence of the particle jet at the exit of the aerodynamic lens.

Moreover, and in general, the Figures 9 (a) to 9 (c) show that the best way to control the divergence of the particle jet at the exit of the aerodynamic lens is to reduce the value of the exit diaphragm diameter of this lens from the value to obtain an optimally collimated jet, so to favor a half-angle of negative divergence (configuration of the Figure 5 (b) ).

However, in some cases, for example for 50 nm polystyrene particles, an output diaphragm diameter value greater than the value to obtain an optimally collimated jet may be required to obtain a well controlled divergent jet. In this case, the half-angle of divergence is positive (configuration of the Figure 5 (c) ).

In the simulation conditions that led to the Figures 9 (a) to 9 (c) , particle jet transmission has also been evaluated.

So, the figure 10 provides the evolution of the transmission rate as a function of the diameter of the exit diaphragm of the aerodynamic lens. More specifically, the Figure 10 (a) is interested in gold (Au), according to sizes between 10nm and 2 microns. The Figure 10 (b) is interested in silicon (Si), in sizes between 50nm and 2 microns. The Figure 10 (c) is interested in polystyrene, in sizes between 50nm and 2 microns.

In the experimental tests and previous simulations, the inlet pressure of the aerodynamic lens was set at 4mbar.

The same simulation campaigns were therefore carried out for a pressure at the entrance of the aerodynamic lens of 3mbar on the one hand and 5mbar on the other hand. The applicant realized that this had an influence on the maximum value of the divergence half-angle that could be obtained. The applicant also realized that decreasing or increasing the aerodynamic lens inlet pressure, compared to a 4mbar reference, decreased this maximum value. In general, however, the results were of the same nature.

Also, to implement the method, it will be possible to envisage an inlet pressure of between 2mbar and 5mbar, preferably between 3mbar and 5mbar and more advantageously of 4mbar.

It should also be noted that the experimental tests and previous simulations demonstrate that the control of the divergence of the jet can be performed by adjusting only the diameter of the outlet diaphragm 25, since the other diaphragms remain with a fixed diameter.

In the above description, we have relied on an aerodynamic lens ( figure 2 ) including five chambers and therefore as many diaphragms other than the output diaphragm, with particular dimensions.

Nevertheless, the method according to the invention can be implemented with any type of aerodynamic lens existing, however providing an output diaphragm whose diameter is adjustable.

By reducing the number of diaphragms within the aerodynamic lens, the possibilities of obtaining a collimated jet are reduced to a certain type (density) of particles and to a certain size of particles.

Nevertheless, the possibilities of obtaining a highly divergent particle jet are increased for some types of particles and particle sizes. Thus, it is possible to obtain a greater half-angle of divergence than with an aerodynamic lens such as that represented on the figure 2 Furthermore, in a wider particle size range, particularly to large sizes and for equivalent particle densities or even for denser particles with similar sizes.

This may therefore be of interest for certain applications, for example when it is desired to perform a homogeneous deposition of particles over large areas.

The figure 11 presents such a possibility, where two chambers CH1, CH2 and three diaphragms 20 (inlet diaphragm), 25 (outlet diaphragm) and 24 (diaphragm separating the two chambers CH1, CH2) are observed. On this figure 11 , the outlet diaphragm 25 has an adjustable diameter, the diaphragm 24 is non-removable and has a given diameter, not adjustable.

Finally, the inlet diaphragm 20 has a given diameter and can in particular, as shown in FIG. figure 11 , be otherwise non-removable and have a non-adjustable diameter. In the latter case, the outlet diaphragm 25 is the only diaphragm of the aerodynamic lens which has an adjustable diameter.

Furthermore, and irrespective of the number of chambers provided within the aerodynamic lens, simulations have shown that, besides the adjustment of the diameter d _s of the exit aperture, the use of a diaphragm 24 ( figure 2 ) of a lower thickness than that considered in the prior art of the figure 1 (10mm) had a positive impact on the control of divergence of large particles, typically around the micron and / or high density.

It can therefore, under certain conditions, be beneficial to provide a thin diaphragm 24 e, for example between 0.2mm and 5mm, between 0.2mm and 3mm, between 0.2mm and 2mm or between 0.2mm and 1mm. , 5mm.

In fact, the Applicant has thus demonstrated that the thickness e of the inlet diaphragm of the chamber having said outlet diaphragm of the aerodynamic lens 100 could have a positive impact on the control of the divergence of the particle jet.

In the above description, we have relied on one realization ( figure 2 ) for which the diameters of figure 11 ) or each figure 2 ) diaphragm other than the exit diaphragm of the aerodynamic lens was becoming smaller since the entry of the aerodynamic lens to its output.

This is just an example.

There are indeed aerodynamic lenses where this characteristic is not respected.

The invention of being able to adjust the diameter of the exit diaphragm of the aerodynamic lens, therefore applies also in this case.

Furthermore, still in the foregoing description, we have presented a case where the outlet diaphragm 25 of the aerodynamic lens has an iris of diameter adjustable by a manually adjustable MOL wheel.

Alternatively, it is possible to automate the system, by connecting the iris diaphragm 25 to a MOT motor, on which the output diaphragm 25 is mounted, which MOT motor is controlled by an external controller C, that is to say not belonging to the diaphragm 25.

This possibility is schematized on the figure 12 .

• o n chambres 10 à 14, avec n ≥ 2, lesdites chambres étant séparées l'une de l'autre par un diaphragme non amovible et présentant un diamètre donné, non réglable;
• o un diaphragme, dit diaphragme d'entrée 20, destiné à former une entrée de la lentille aérodynamique pour un jet de particules, ledit diaphragme d'entrée présentant un diamètre donné ; et
• o un autre diaphragme, dit diaphragme de sortie 25, destiné à former une sortie de la lentille aérodynamique pour ce jet de particules, ledit diaphragme de sortie présentant un diamètre donné ;

et dans lequel le diaphragme de sortie 25 est monté de façon amovible au sein de la lentille aérodynamique 100' et en ce que ledit ensemble comprend, en outre, au moins un diaphragme complémentaire 25' présentant un diamètre différent de celui du diaphragme de sortie 25, ledit au moins un diaphragme complémentaire 25' étant destiné à être monté de façon amovible dans la lentille aérodynamique en lieu et place dudit diaphragme de sortie.According to another variant, much simpler to implement industrially, it is possible to provide, in place of the aerodynamic lens 100, an assembly comprising an aerodynamic lens 100 'comprising:

• chambers 10 to 14, with n ≥ 2, said chambers being separated from each other by a non-removable diaphragm and having a given diameter, not adjustable;
• a diaphragm, called the inlet diaphragm 20, intended to form an inlet of the aerodynamic lens for a particle jet, said inlet diaphragm having a given diameter; and
• o another diaphragm, said output diaphragm 25, intended to form an output of the aerodynamic lens for this particle jet, said output diaphragm having a given diameter;

and wherein the outlet diaphragm 25 is removably mounted within the aerodynamic lens 100 'and in that said assembly further comprises at least one complementary diaphragm 25' having a different diameter than the diaphragm 25, said at least one complementary diaphragm 25 'being intended to be mounted removably in the aerodynamic lens instead of said outlet diaphragm.

In this assembly, the output diaphragm is not in the form of an iris, controlled manually or not, whose diameter d _s is adjustable.

Indeed, the diameter of the output diaphragm is fixed. However, since this output diaphragm is removably mounted within the aerodynamic lens, it can be changed as desired from another set of diaphragms 25 ', 25 ", ..., 25 ⁿ having different diameters from each other.

It is thus possible to adjust the diameter d _S of the outlet diaphragm 25 by simply changing the diaphragm.

$d_S^{ʺ},\dots ,d_S^n$

différents entre eux et tous différents du diamètre de sortie d_s du diaphragme 25 monté sur la lentille aérodynamique 100'.The figure 13 is a representative diagram of such an assembly 200, comprising an aerodynamic lens 100 'in which is housed, at the output of the aerodynamic lens and removably, an outlet diaphragm 25 and a set of diaphragms 25', 25 ",. .., 25 ⁿ (complementary diaphragms) of diameters $d_S^{\text{'}},$

$d_S^{"},...,d_S^{\mathrm{not}}$

different from each other and all different from the outlet diameter d _s of the diaphragm 25 mounted on the aerodynamic lens 100 '.

To achieve a removable assembly, one can for example change the structure of the aerodynamic lens 100 'at its output. For example, it is possible to mount a diaphragm on the end of the aerodynamic lens 100 'by MM mounting means such as screws, bolts, glue on the peripheral wall of the aerodynamic lens.

According to another possibility (not shown), it is possible to provide, on the aerodynamic lens 100 ', and at its end, a wall provided with a notch adapted to receive any of the diaphragms 25, 25', 25 " , ..., 25 ".

Claims (20)

A method for controlling the divergence of a vacuum particle jet with an aerodynamic lens, said aerodynamic lens (100, 100 ') comprising: n chambers (10 to 14) with n ≥ 2, said chambers being separated from each other by a non-removable diaphragm and having a given, non-adjustable diameter; a diaphragm, referred to as an inlet diaphragm (20), for forming an aerodynamic lens inlet for a particle jet, said inlet diaphragm having a given diameter (d ₁ ); and - Another diaphragm, said output diaphragm (25), for forming an aerodynamic lens output for this particle jet, said output diaphragm having an adjustable diameter; said method comprising; a step of generating the particle jet from the inlet to the vacuum outlet of the aerodynamic lens (100, 100 '); and a step of adjusting the diameter (d _s ) of the output diaphragm to control the divergence of the particle jet, A method according to claim 1, wherein the diameter (d _s ) of the output diaphragm (25) is set in a range of values strictly smaller than the diameter (d ₁ ) of the input diaphragm. Method according to one of the preceding claims, wherein the aerodynamic lens (100, 100 ') has n chambers, with n ≥ 3, and therefore n diaphragms other than the output diaphragm, two successive chambers being separated from each other. another by a non-removable diaphragm and having a given diameter, not adjustable. Method according to one of the preceding claims, wherein the inlet diaphragm is non-removable and has a non-adjustable diameter. Method according to the preceding claim, wherein the diameter (d _s ) of the outlet diaphragm (25) is set to a value strictly smaller than the diameters of said n diaphragms other than the outlet diaphragm. Method according to one of the preceding claims, wherein the inlet pressure of the aerodynamic lens (100, 100 ') is between 2mbar and 5mbar, preferably between 3mbar and 5mbar. Aerodynamic lens (100) for carrying out a method according to one of the preceding claims, comprising: n chambers (10 to 14) with n ≥ 2, said chambers being separated from each other by a non-removable diaphragm and having a given, non-adjustable diameter; a diaphragm, referred to as an inlet diaphragm (20), for forming an aerodynamic lens inlet for a particle jet, said inlet diaphragm having a given diameter (d ₁ ); and another diaphragm, called the output diaphragm (25), intended to form an aerodynamic lens output for this particle jet; characterized in that the outlet diaphragm (25) has an adjustable diameter. Aerodynamic lens (100) according to the preceding claim, comprising n chambers, with n ≥ 3, and therefore n diaphragms other than the outlet diaphragm (25), two successive chambers being separated from each other by a non-removable diaphragm and having a given diameter, not adjustable. Aerodynamic lens (100) according to one of claims 7 or 8, wherein the number n of chambers and therefore of diaphragms other than the outlet diaphragm (25) is such that n ≥ 5 and, for example, such that n ≤ 15, two successive chambers being separated from one another by a non-removable diaphragm and having a given diameter, not adjustable. Aerodynamic lens (100) according to one of claims 7 to 9, wherein the inlet diaphragm is non-removable and has a non-adjustable diameter. Aerodynamic lens (100) according to one of claims 7 to 10, wherein the outlet diaphragm (25) is in the form of an iris whose diameter (d _S ) is adjustable by a manually operable wheel. Aerodynamic lens (100) according to one of claims 7 to 10, wherein the outlet diaphragm (25) is in the form of an iris whose diameter is adjustable by a controlled motor. Aerodynamic lens (100) according to one of claims 7 to 12, wherein the inlet diaphragm of the chamber comprising said outlet diaphragm (25) of the aerodynamic lens has a thickness (e) of between 0.2mm and 5mm . Assembly (200) for carrying out a method according to one of Claims 1 to 5, comprising an aerodynamic lens (100 ') comprising: chambers (10 to 14) with n ≥ 2, said chambers being separated from each other by a non-removable diaphragm and having a given, non-adjustable diameter; a diaphragm, referred to as an inlet diaphragm (25), for forming an aerodynamic lens inlet (100 ') for a particle jet, said inlet diaphragm (20) having a given diameter (d ₁ ); and o another diaphragm, said output diaphragm (25), for forming an aerodynamic lens output for this particle jet, said output diaphragm having a given diameter; characterized in that the outlet diaphragm (25) is removably mounted within the aerodynamic lens (100 ') and in that said assembly (200) further comprises at least one complementary diaphragm (25', 25 '). ^N ) having a diameter different from that of the exit diaphragm (25), said at least one complementary diaphragm being adapted to be removably mounted in the aerodynamic lens in place of said outlet diaphragm. Assembly (200) according to the preceding claim, wherein the aerodynamic lens (100 ') has n chambers, with n ≥ 3, and therefore n diaphragms other than the output diaphragm, two successive chambers being separated from one another by a non-removable diaphragm and having a given diameter, not adjustable. Assembly (200) according to one of claims 14 or 15, wherein the number n of chambers and therefore of diaphragms other than the exit diaphragm is such that n ≥ 5 and, for example, such that n ≤ 15, two chambers successive ones being separated from each other by a non-removable diaphragm having a given, non-adjustable diameter. Assembly according to one of claims 14 to 16, wherein the inlet diaphragm is non-removable and has a non-adjustable diameter. Assembly according to one of claims 14 to 17, wherein the inlet diaphragm of the chamber comprising said outlet diaphragm (25) of the aerodynamic lens has a thickness (e) between 0.2mm and 5mm. Use of an aerodynamic lens (100) according to one of Claims 6 to 11 or an assembly (200) according to one of Claims 12 to 15 for depositing, under vacuum, particles on a target surface (SC) . Use according to the preceding claim, wherein the target surface has a surface greater than or equal to cm ² .

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