WO2021069620A1

WO2021069620A1 - Cvd reactor for manufacturing synthetic films and methods of fabrication

Info

Publication number: WO2021069620A1
Application number: PCT/EP2020/078330
Authority: WO
Inventors: David Rats; Christophe Provent
Original assignee: Neocoat Sa
Priority date: 2019-10-11
Filing date: 2020-10-08
Publication date: 2021-04-15

Abstract

The invention provides a microwave plasma reactor (1) for manufacturing synthetic material via chemical vapor deposition, comprising: - a plasma enclosure (2) comprising a base plate (102), a top plate (108) and a side wall (104, 106) extending from said base plate (102); - one or several plasma sources (100) comprising at least one microwave generator (100') configured to generate microwaves in said plasma enclosure (2); - an array (10) of plasma applicators (100'''), which extremities are positioned in the plasma enclosure (2) according to a predetermined pattern, The invention is also achieved by methods of fabrication of coatings and to the use of the reactor (1) of the invention so as to provide coated samples. Such coated samples are also covered by the invention.

Description

CVD REACTOR FOR MANUFACTURING SYNTHETIC FILMS AND METHODS OF FABRICATION

Field of invention

The present invention relates to a method to manufacture thin film hard materials and also to a reactor for manufacturing thin films of hard materials, such as synthetic diamond and related materials.

Background of invention

Synthesis of thin films of hard materials such as diamond using chemical vapor deposition (CVD) techniques is well known and described in for example the Journal of Physics: Condensed matter, 21, 36 (2009) which gives an overview of diamond related technologies. An overview of CVD diamond deposition techniques and materials may be found in: R.S. Balmer et al. “Chemical vapor deposition synthetic diamond: materials, technology and applications”, J. Phys.; Condensed Matter, Vol.21, nr.36, 36422, (2009). In particular, diamond films possess a number of outstanding physical properties including extreme hardness, high thermal conductivity and wide-band optical transmission. This makes diamond in particular attractive for a number of applications.

The deposition of polycrystalline diamond obtained with CVD technique is based on the principle of decomposing a gas mixture comprising a carbon and a hydrogen precursor. The activation in the gas phase is performed either by Hot Filament Chemical Vapor Deposition (HFCVD) or by means of a microwave plasma (Microwave Plasma Chemical Vapor Deposition, or MPCVD) or DC Arc Plasma.

For industrial applications, it is important to have a large deposition area (>0.1m²) in order to achieve cost-effective diamond deposition.

The pieces which are able to be coated with polycrystalline diamond have not exclusively simple shapes such as a full disk or a full rectangle with a relatively small thickness ( lOmm), but they could exhibit more complex shapes such as rings, prisms, polyhedrons, tori or ellipsoids.

Furthermore in some applications the substrate may have a simple shape such as a disc but the deposition of the diamond layer must be made in a form such as rings, or polyhedrons, ellipses, that must have at least one through-hole or any other shape such a for example a cross.

HFCVD techniques allow depositing on various large size substrates but the surface deposition is limited to rectangle shaped depositions because of the arrays of filaments.

It is also possible to use FIFCVD technique to deposit on complex shaped parts, but it is not possible to limit the depositions to the selected area to be coated. It would impose an unacceptable huge consumption of energy for filament heating which is not compatible with cost-effective production.

Microwave plasma chemical vapor deposition (MPCVD) techniques present several advantages such as: no potential contamination from filaments, high atomic hydrogen concentration that allows obtaining well controlled microstructures and a high quality of the deposited diamond films.

In the last 20 years several types of MPCVD reactors have been proposed such as ones based on a quartz tube, a quartz bell jar and having a cylindrical, or ellipsoidal or non-cylindrical shaped cavity of the reactor.

Recent MPCVD reactors are designed by choosing at least a resonance mode, a coupling system, a dielectric element and the 3D-dimension of the cavity. Reactors of prior art are all designed to coat disc shaped surfaces. For example, document US 20140230729 A1 describes a microwave plasma reactor for manufacturing synthetic diamond. The reactor described in US 20140230729 A1 uses a TM011 resonant mode and provides a spherical shaped plasma which allows coating the full surface of a disc with a thin film diamond layer. As the plasma in the reactor described in US 20140230729 A1 has a spherical shape it does not allow to deposit other shapes than a disc like shape deposition.

All plasma reactors based on a resonant cavity are limited to depositions on a surface of 2D disks or rectangles placed in a disk, or a ring with limited dimensions. It is not possible to deposit on 3D shape parts or to realize non- uniform coatings with current plasma reactors.

There is a growing demand for processes and reactors that would allow realizing thick diamond films on surfaces such as silicon or silicon carbide that have annular, toroidal or ellipsoidal shape or other 3D or particular 2D shaped

One application is for example for rotary seals for circulation pumps in industrial machines or oil industry. But there are also many other potential applications.

None of the available reactors or methods allows realizing in a cost-effective way films of diamond having a thickness of about 1 to more than 100 pm on a complex shaped substrate that may have an outside diameter of more than 400mm or annular parts that have a large difference between their outer diameter (OD) and inner diameter (ID). Also, none of the available reactors or methods allows realizing in a cost-effective way complex shaped films of diamond having a thickness of about 1 to more than 100 pm on a flat substrate, that may have outside diameter of more than 400mm or that may be annular parts that have a large difference between their outer diameter (OD) and inner diameter (ID). Existing MPCVD reactors are limited to diameters of about 100-200mm for a disk or 300-400mm for a ring, and the deposition by HFCVD reactors are too energy voracious or not allow to deposit on a selective area. On the other side none of the available reactors allow to perform deposition layers on preselected specific areas or surfaced of small 3D shaped pieces such as watch components .

None of the methods or devices of prior art are capable of realizing a complex shaped synthetic hard films or layers in a cost-effective industrial way.

So there is a need for new reactors that provide a largely improved deposition freedom of the layers and the choice of substrate that may have a complex 3D shape of its outer or inner surfaces. Summary of the invention

It is the object of the invention to provide a reactor and methods that are capable of realizing a complex shaped synthetic hard films or layers in a cost- effective industrial way.

The reactor of the invention provides a largely improved deposition freedom of the layers and the choice of substrate that may have a complex 3D shape of its outer or inner surfaces. Furthermore, the reactor of the invention allows to provide an improved energy and gas consumption efficiency, compared to prior art reactors, because the coatings may be deposited only on predetermined areas that need to be coated.

In a first aspect the invention is achieved by a microwave plasma reactor for manufacturing components comprising a synthetic layer made of a hard material via chemical vapor deposition, and comprises:

- a plasma enclosure comprising a base plate, a top plate and a side wall extending from said base plate;

- one or several plasma sources comprising at least one microwave generator configured to generate microwaves in said plasma enclosure

- an array of plasma applicators, each associated to at least one of said microwave generators , having an output dielectric window to the side of said plasma enclosure and suitable to generate each a localized plasma in the plasma enclosure, said dielectric windows being positioned in the plasma enclosure according to a predetermined pattern defined by a border described by a predetermined polygon.

- a gas flow system, comprising at least one gas inlet , for feeding process gases into the plasma enclosure and removing them therefrom; a substrate holder defining an area to adapt a substrate ;

The reactor is configured to operate preferably at a temperature higher than 400° C and achieve localized deposition of diamond coatings on a substrate. A big advantage of the reactor is that it allows depositing a hard material in a focused way on complex and not continuous shapes without wasting consumables and energy by tentatively deposit the material where it is not required (i.e. in the center of a ring where there is a hole and no substrate to cover).

The reactor of the invention also allows to realized deposited patterns of diamond and related materials (i.e. SiC, BCN, amorphous carbon) having not only simple areas, but having predetermined shapes, such as for example a star, a cross, an hexagon, a ring, the border of which is very precisely determined.

The reactor of the invention allows to reduce power consumption when depositing on complex shaped parts, in comparison to other CVD techniques such as HFCVD with which it is not possible to limit the depositions to the selected area to be coated. As a consequence the reactor avoid the unacceptable huge consumption of energy required for filament heating of HFCVD which is not compatible with cost-effective production.

Thanks to the arrangement of the plasma sources in accordance with the shape of the substrate, the reactor of the invention allows a quick deposition compared to another type of reactor which would have a fixed small localized plasma source and a moving substrate holder that would allow to expose successively all parts of the substrate top the plasma. In the case of such other type of reactor the deposition would only occur on the part of the substrate which is below the plasma source and not on the rest of the substrate with the consequence that much more time would be required to cover the entire substrate, and also a gradient of diamond film properties as grain size or non-diamond carbon codeposition content.

The reactor of the invention is not a reactor that has a resonating cavity because a reactor based on a resonating cavity can generate only one type of plasma shape and localization. The reactor is not a CVD reactor for low temperature deposition of diamond or related materials, but a reactor that requires high operating temperatures, typically higher than 400° C.

In an embodiment at least one of said plasma sources is configured to be activated or deactivated during the operation of the reactor.

In an embodiment said predetermined pattern is a fixed defined pattern, which means that the shape of the arrangement is defined during the reactor construction and cannot be simply change during the operation of the reactor.

In an embodiment at least one channel, having a predetermined shape, is configured to move at least one applicator along said channel. The advantage of such channel is that the position of the applicator can be thinly tuned to perfectly fit the substrate shape, or also that the position of the applicator can be changed during the process to progressively cover other areas of the substrate along the shape of the channel.

In an embodiment the microwave plasma reactor comprises a central cylindrical wall. In the case of annular or annular-like (polygons with a central hole) substrates, this central cylindrical wall allows optimizing the deposition on the annular shape by reducing the volume of the cavity to useful area focused on the substrate. Advantages of such focusing are that gas and energy consumption are optimized and also the activated gas phase is focused on the substrate and not dispersed in a large reactor chamber.

In an embodiment the microwave plasma reactor comprises at least one channel having a predetermined shape, for moving at least one applicator along said channel. This allows to provide the possibility to deposit layers that have non uniform thicknesses, for example for realizing local bulges. It allows also to provide multiple layers having different widths or composition, or overlapping layers.

In an embodiment the microwave plasma reactor at least one of said applicators can be moved and/or reoriented in 3D inside the plasma enclosure. By adapting the speed according to a predetermined speed pattern in function of time, non uniform layers may be realized. For example it is possible to realized steps on a deposited layer, or to fill apertures in a first deposited layer with other materials than the first deposited layer. In variants at least one applicator that is configured to move during the deposition process may undergo a movement in a direction orthogonal to surface defined by the displacement movement of the applicator. This provides also means to modulate local thicknesses of deposited layers.

In an embodiment the microwave plasma reactor is configured to operate at temperatures higher than 400° C.

In an embodiment the microwave plasma reactor is configured to deposited layers on substrate, the materials of the layers being chosen among Diamond (C), SiC, CN, B4C, Si3N4, amorphous carbon or a combination of them.

In an embodiment at least one of said applicators can be moved and/or reoriented inside the plasma enclosure.

In an advantageous embodiment the microwave plasma reactor comprises at least two of the output dielectric windows have a different distance relative to the wall in which the plasma applicators are arranged. This allows to adapt the shape of the generated plasma and so the 3D shape of the deposited layers.

In a second aspect the invention is achieved by method of fabrication of coated samples comprising the steps of :

- providing a reactor, as described, comprising an array of plasma applicators;

- activating a predetermined number of plasma applicators so as to provide a predetermined shape of a plasma inside said enclosure;

- realizing a coating having a predetermined shape and predetermined properties on a sample present in said plasma enclosure.

In an embodiment a translatable plasma applicator is movable according to a predetermined speed time scheme.

In an embodiment the method of fabrication of coated samples comprises the steps of: providing a reactor as described and comprising at least one translatable plasma applicator arranged in a channel of a plate of the reactor ; - activating said translatable plasma applicator;

- moving said translatable plasma applicator along said channel;

- realizing a coating having a predetermined shape and predetermined properties on a sample present in said plasma enclosure (2).

The invention is also achieved by the use of a microwave plasma reactor as described to realize coated samples comprising a hard coating layer, the coating layer being applied on a substrate that has a predetermined shape by using an arrangement of plasma sources that has a similar predetermined shape.

Brief description of the drawings

Figure 1 shows a vertical cross section of a reactor of the invention, comprising an array of microwaves source arranged in a top plate of the reactor;

Figure 2 shows a vertical cross section of a reactor of the invention, having a cylindrical inner wall;

Figure 3 shows a top view of a horizontal cross section of a reactor of the invention, illustrating the formation of an annular plasma provided by a plurality of localized plasma sources arranged on an ellipse;

Figure 4 shows a top view of a horizontal cross section of another reactor of the invention, illustrating the formation of an annular plasma provided by a plurality of non-identical localized plasma sources arranged around a cylindrical wall;

Figure 5 shows a vertical cross section of a reactor of the invention, comprising microwave sources arranged in a top plate and in a lateral wall of the reactor; the figure illustrates pairs of plasma applicators that are connected to a single plasma generator. The figure illustrates also a toroidal sample present in the reactor chamber;

Figure 6 illustrates a 2D array arrangement of plasma sources of a reactor of the invention in operation. In the figure 6 full discs illustrate activated plasma sources and blanc discs that represent non activated plasma sources, providing an L-shaped plasma source and so an L-shaped film deposition; Figure 7 illustrates a top plate of a reactor of the invention, in which a portion of a plasma source may be moved in a channel provided in the top plate;

Figure 8 illustrates a vertical section of a reactor of the invention, comprising plasma applicators of which at least one is configured so that its extremity in the plasma chamber is spatially orientable;

Figure 9 illustrates a reactor of the invention comprising two chambers that are in connection, each chamber comprising a different number of different types or different oriented plasma applicators. The figure illustrates a translation stage to move a to be coated substrate from one chamber to the other chamber;

Figure 10 illustrates a reactor of the invention comprising a deformable or orientable plate in which plasma applicators are positioned;

Figure 11 illustrates a typical plasma source comprising a generator, a power transmission coaxial cable , an microwave coaxial applicator and a dielectric window.;

Figure 12 shows a coating or a cross section of a plasma being a substantially circular ring defined by an inner radius and an outer radius;

Figure 13 shows a coating or a cross section of a plasma being an elliptical ring;

Figure 14 shows a coating or a cross section of a plasma being a polygonal ring;

Figure 15 shows a sample having the shape of a hollow ellipsoid;

Figure 16 shows a sample having the shape of a hollow polyhedron;

Description of the invention

The present invention will be described with respect to particular embodiments and with reference to certain drawings, but the invention is not limited thereto. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to the practice of the invention.

It is to be noticed that the term “comprising” in the description and the claims should not be interpreted as being restricted to the means listed thereafter, i.e. it does not exclude other elements.

Reference throughout the specification to “an embodiment” means that a particular feature, structure or characteristic described in relation with the embodiment is included in at least one embodiment of the invention. Thus, appearances of the wording “in an embodiment" or, “in a variant”, in various places throughout the description are not necessarily all referring to the same embodiment, but several. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a skilled person from this disclosure, in one or more embodiments. Similarly, various features of the invention are sometimes grouped together in a single embodiment, figure or description, for the purpose of making the disclosure easier to read and improving the understanding of one or more of the various inventive aspects. Furthermore, while some embodiments described hereafter include some but not other features included in other embodiments, combinations of features if different embodiments are meant to be within the scope of the invention, and from different embodiments. For example, any of the claimed embodiments can be used in any combination. It is also understood that the invention may be practiced without some of the numerous specific details set forth. In other instances, not all structures are shown in detail in order not to obscure an understanding of the description and/or the figures.

The wording “horizontal cross section of the reactor " in the document is defined as a cross section in an X-Y plane which is defined as a plane parallel to the bottom plate of the reactor , which is preferably parallel to the substrate holder of the reactor. The wording “vertical” means here perpendicular to said bottom plate. A vertical cross section of the reactor is a cross section in a plane that comprises the vertical axis Z that is defined orthogonal to said bottom plate . X-Z and Y-Z planes define vertical planes that are orthogonal to the bottom plate. Horizontal planes are X-Y plane that are parallel to the bottom plate . A radial direction in the reactor means a direction defined in a horizontal cross section, so defined also in a horizontal plane.

The wording “movable” herein means to provide ways to translate in three dimensions as described in the C,U,Z referential, and/or to rotate relative to the three axes C,U,Z .

Thicknesses in the reactor are defined herein as thicknesses in the vertical direction, i.e. in the direction of the Z-axis.

It is understood that the reactor provides in operation at least one localized plasmas are provided by plasma sources. The localized plasmas may be arranged in a fixed arrangement or may be mobile as described in detail further.

A plasma source, also defined as microwave source, is illustrated in Fig.11 and is a generic term meaning the system that provides a localized plasma 30, 31- 35.

A plasma source 100 of the invention comprises at least:

- a microwave generator 100';

- microwave transmission means 100";

- a microwave applicator 100'" defined also as applicator body, having an output element 100^iv at its extremity arranged into the reactor. The output element 100^iv is for example a dielectric window 100^iv. This window or output surface is part of the applicator that is preferably a coaxial applicator but not necessarily so. It is understood that other means may be provided to generate localized plasmas 30, 31-35.

In the reactor of the invention at least one plasma applicator 100’” is present, associated to at least one of said microwave generators 100’. Each plasma applicator 100”’, defined also as “applicator”, is configured to provide in operation, a local plasma 30, 31-34 that is localized in proximity to the end part of the applicator, in principle close to said dielectric window. In embodiments a small volume without plasma may be present, in operation of the reactor, between said dielectric window and a local plasma. Said small volume may be defined by a layer having a width of typically l-2mm, possibly smaller than 1mm. In the figures, only a portion of the plasma sources 100 are shown and are for reasons of simplicity of the Figures, indicated by the number 100, i.e. only the extremity of the plasma sources 100 are shown. The dielectric windows 100^iv are not shown everywhere in the drawings for reasons of clarity. Dielectric windows or other types of output structures or windows are not necessarily in contact with said microwave applicators 100'". Output windows may have any form such as a curved form. In variants, the form of the output windows such as dielectric windows may be chosen to optimize the form of the localized plasmas 30-34.

The localized plasmas 30, 31-35 that are provided by the plasma sources 100 are defined as localized plasma sources or point-like plasma sources in the sense that the plasma volumes are created, in operation close to or in contact with the output elements 100^iv (e.g. dielectric window) of the plasma applicators, as illustrated in the schematic drawing of Figure 11. Localized plasma (or defined also as plasma balls) 30, 31-35 have typical diameters D’ of the order of the diameter of the extremities, for example the dielectric windows 100^iv. Localized plasma volumes, also defined as plasma balls, have typically a diameter of 0.1 to 10 times the diameter of the extremities, e.g. dielectric windows, and have not necessarily a spherical shape, rather typically a flattened spherical or ellipsoidal shape. By placing plasma applicators in proximity a plasma volume may be created that has typically the volume of two adjacent localized plasmas but having another shape than just the geometrical addition joining of the two localized plasmas as illustrated in Figs 3 and 4 wherein a plurality of localized plasma balls 30 join to form a continuous ring like plasma 3.

A substrate 1000 is also defined as a component on which a coating has to be applied by the reactor, on at least one portion of its inside or outside surface. Coatings may be multilayer coatings and/or non-homogenous coatings and may be coatings having different compositions. For example, a hybrid coating may be deposited comprising for example at least one diamond layer and/or at least one layer made of another material such as SiC.

In a first aspect the invention proposes a microwave plasma reactor 1 for manufacturing synthetic material via chemical vapor deposition, and having a largely improved deposition flexibility and deposition quality than existing reactors of prior art. The reactor of the invention comprises:

- a plasma enclosure comprising a base plate, a top plate and a side wall extending from said base plate to said top plate, said plates and wall may comprise curved portions;

- one or several microwave plasma sources 100 (a detailed example is illustrated in Fig.11) arranged in said plasma enclosure 2 and configured to provide microwaves and generate localized plasmas 30, 31-34 in said enclosure;

- an array 10 of plasma applicators 100’” (i.e. the extremity of the plasma sources 100), each associated to at least one of said microwave generators 100’, having each preferably a dielectric window 100^IV to the side of said plasma enclosure 2 and suitable to generate each a localized plasma in the plasma enclosure 2, said plasma applicators 100”’ being configured to be positioned in the plasma enclosure according to a predetermined pattern; This predetermined pattern may be fixed or adaptive, or may be movable in operation, as illustrated in Figs. 6 and 7. Fig. 6 shows a top view in a plane comprising a predetermined fixed and addressable arrangement of output windows 100a-100n, that are preferably dielectric windows. Addressable meaning that the applicator may provide a localized plasma when put into operation.

- a gas flow system, comprising at least one gas inlet 131, for feeding process gases into the resonance cavity and removing them therefrom, and at least one gas outlet 133; a substrate holder defining an area to adapt a substrate;

The plasma reactor is operable at high temperatures, preferably temperatures higher than 400° C, preferably higher than 500° and even more preferably higher than 600° .

The reason to use high temperatures is that it allows to achieve a higher deposition rate of the coating and makes the method a cost-effective process. H igh temperature in operation of the reactor is also necessary to achieve diamond films with large grain microstructure, i.e. having a grain size greater than lpm for a lOpm thick coating, and thus obtain higher values of thermal or electrical conductivities. However, the reactor can also be used to produce coatings with small grains of less than lpm.

Some reactors of prior art, such as HFCVD or MWCVD resonant cavity reactors, have been adapted to be able to deposit thick and homogeneous hard layers, particularly layers such as diamond or SiC.

There exists no reactor of prior art that may achieve the performances as the reactor of the invention. Limitations of reactors of prior art reside in the following reasons.

- HFCVD reactors cannot be used to deposit selectively on particular shape and can only be used to treat continuous surfaces

- The ratio energy for filament heating on useful surfaces for HFCVD reactor is not compatible with cost-effective production.

- MWCVD reactors with resonant cavity have limited deposition area to a diameter of 75mm at 2.45GHz and 200mm at 915MHz.

- Large HFCVD and MWCVD reactors with resonant cavity allow only to deposit on 2D substrates

In an advantageous embodiment, the extremity 100’^vof the applicator bodies 100’”, that may be or may comprise dielectric windows 100^IV, are positioned in the plasma enclosure 2 according to a predetermined pattern. This predetermined pattern may be fixed or adaptive, or may be movable in operation, as illustrated in Figs. 6 and 7. Fig. 6 shows a top view of the reactor comprising a predetermined fixed and addressable arrangement of dielectric windows lOOa-lOOn. The wording “addressable” meaning that the applicator may provide a localized plasma when put into operation.

The preferable shape of the applicator body 100’” is a cylinder defined by its diameter, D and its length L. The length L is preferable a multiple of a quarter of the microwave wavelength (31mm for 2.45GHz or 82mm for 915MHz) generated by the microwave applicators . The ratio between L and D depends on the impedance of the applicator and is typically 50 Ohms. For a microwave frequency of 2.45GHz, L can vary from 60 to 250mm with typical values from 90mm to 160mm The diameter D can vary from 15 to 60mm with typical value from 25 to 40mm. The plasma 30 generated by the applicator 100 at the end of dielectric window 100^IV has preferably a ball-like shape with a diameter D’ and a thickness T. The local plasma diameter D’ (Figure 1) is typically greater than the diameter D of an applicator (Figure 11) and strongly depends on the pressure inside the reactor, higher is the pressure lower D’ is. A typical value of T is 1 to 10mm.

The distance between each applicator D” is the optimal distance to obtain a good homogeneity of coating. D” can vary from 10 to 100mm with typical values from 20 to 40mm

The number of applicators is thus depending both of the surface deposition and the optimal distance between each applicator D”.

In embodiments, as illustrated in Fig.5, pairs 10a, 10b of plasma applicators 10 may be arranged in at least one of the walls of the reactor.

In an advantageous embodiment said predetermined pattern is a fixed geometrical pattern as illustrated in Fig. 3, 4. In operation all applicators may be active or only a portion of the applicators s may be active such as illustrated in Fig 6 wherein a form “L" is provided allowing to deposit a coating having substantially an “L-Shaped” form. For example, in a variant, the array of applicators may be arranged according to an L-shape without other applicators present. In variants the applicator bodies 100’” may be arranged in a non- homogenous arrangement.

In an advantageous embodiment illustrated schematically in Fig.7 said predetermined pattern is realized by at least one moving and addressable applicator. The movement is performed according to a predetermined path.

In embodiments that least one channel 112 has a predetermined shape to move at least one applicator along said channel 112.

In an advantageous configuration the channel may present bifurcations, for example a channel in the shape of the letter Y. The channel may also have a spiral shape.

In embodiments the reactor may be configured to program a predetermined speed pattern of the applicator that moves into a channel. For example, in a configuration the system may be configured to program a halt during a predetermined time lag in order to create locally a denser coating, for example to realize a bulge in the coated layer, or to realize an array of dots or a wall.

In variants more than 1 applicator may be arranged in a single channel 112. In variants the reactor may comprise a wall into which crossing channels are provided..

It is understood that the above describes embodiments implying a channel may also be realized without channels in a plate. For example, a motorized system may be used to move the applicators. In variants movable aplicators may also be guided onto guiding rails.

In embodiments movable applicators may be arranged so that different types of layers may be realized on top of each other. For example a coating may have the form of a ring and may comprise a first ring made of a first material and on top of the first ring a second ring, made of another material, may be deposited.

This may also be realized with a variant of the configuration of Fig.6 wherein different applicators address different geometries. For example a first array of applicators may be operated to deposit a coating in a first form, for example a cross shaped coating, and a second array of applicators, providing different shaped local plasmas, may deposit a second shaped second coating, for example a ring, over the first shaped coating. Such overlapping coating layers may also be realized by a combination of a fixed array of plasma sources 100 and at least one movable plasma source 100.

In an embodiment the applicator may move forward and backward along a guide and may also have movement in a direction orthogonal to the guide, allowing to modulate local thicknesses of the deposited layer.

In an embodiment a portion of the applicators may have a different position in the direction orthogonal to their support. For example, a plurality of applicators may be arranged according to a ring and so that they their ends are closer to the substrate than a second plurality of applicators which end have a greater distance to the substrate. This allows to provide layers having different thicknesses in a plane and realizing for example a cross shaped layer inside a ring layer that has a smaller thickness than the cross-shaped layer. It is generally understood that the applicators may be arranged as well in the top plate 108 , the bottom plate 102 or the walls 104, 106 or to any surface of the plasma enclosure, including the support 120, i.e. the sample holder. Several sample holders may be provided in the plasma chamber and may comprise means to move or orient them during the operation of the reactor.

In an advantageous embodiment, applicators are arranged according to a ring- type distribution having no applicators inside the area defined inside the ring-type arrangement. It is understood that a ring-type distribution as defined here means any distribution of applicators which extremity are arranged so that a central area has no applicator ends, said central area being surrounded by applicators, that may have different locations of their ends in the reactor chamber. The applicators inside a ring distribution may be arranged according to a non-homogeneous arrangement.

In advantageous embodiments more than 5 applicators are arranged into the reactor, possibly more than 10, or even more than 20 or more than 50 applicators. Not all applicators have to be of the same type or the same dimension or the same operating conditions.

In an advantageous embodiment the reactor 1 may be configured so that different plates comprising predefined patterns of holes or holder may be inserted and exchanged in the reactor 1. This is explained further in the method section. For example, for a first coating an annular coating has to be provided and a plate comprises apertures and applicators arranged on a circle. In a second coating step a triangular shaped coating has to be provided. In that case the first plate configured to provide an annular coating is removed from the reactor and a plate configured to provide a triangular coating is inserted in the reactor li variants such a first and second coating step may be provided onto the same substrate 1000.

In an embodiment, as illustrated schematically in Fig.9, the reactor 1 may comprise two plasma chambers la, lb that are in gaseous connection, by for example a load-lock or without load-lock. The at least two plasma chambers la, lb may have different types or sized or numbers of plasma applicators 100, 10’ or arrays 10 of applicators 10. Such a variant of the reactor of the invention 1 may be interesting to perform a first treatment in a first chamber and a second treatment in a second chamber, one of said treatments consists in the deposition of a hard layer. Said first treatment may be for example a treatment to clean and/or roughen the surface. In a variant, translating means t are provided inside the reactor so as to enable to transport a sample from said first chamber to said second chamber or vice -versa. Several treatment steps may be performed in succession for example a process comprising a first treatment in the first chamber, a hard coating in the second chamber and a subsequent treatment again in said first chamber.

In an embodiment, illustrated also in Fig.9 a reactor may comprise at least one applicator 101 that may comprise means so that it can be extended according to different lengths in the plasma enclosure 2. Said means may comprise an articulation so that the extremity of the applicator 101 may be oriented in the enclosure 2.

As illustrated in Fig.8 means may be provided so that the extremity of an applicator can be moved and/or oscillated over an angle Q according to at least one direction in the XYZ referential and/or may be put into vibration during the operation of the reactor 1.

In an advantageous embodiment means are provided between the extremities of different applicators 10’” so as to confine or direct or modify the shape of the localized plasmas 30-34. Such means may be electrical or mechanical means and may be addressable. For example, in order to fine-tune the deposition process, addressable mechanical walls may be present between adjacent dielectric windows. Such walls may be configured to be rotatable or to be flipped or to be changed in position, i.e. may be advanced or retracted in the plasma enclosure.

In variants such as illustrated in Fig.2 the plasma reactor 1 may comprise a central cylindrical wall 140 having a diameter W.

A shaped sample support 21 adapted to the form and size of a sample to be coated may be provided in the reactor 1. Also, the applicators 100 may provide different shaped localized plasma sources 31, 32, 33, 34 that may have different volumes or different physical properties. In variants, the ends 100’^v may have different distances relative to the plate or support in which the array of applicators are arranged. For example, an applicator plate may be flat, and the virtual surface defined by the ends 100’^vof the applicators may define a spherical or parabolic surface. Such arrangement allows to achieve a predetermined shape of the collective plasma defined by the different plasma sources 100 and so the local plasmas 30.

In an embodiment illustrated in Fig.10 the array 10 of plasma applicators and their windows may be arranged on a plate or support which form may be adapted by mechanical and/or electrical means. Fig.10 illustrates a change of a radius of curvature of the support plate of the applicators.

In an embodiment illustrated in Fig. 1 the substrate holder 120 is able to move in all directions in the referential X-Y-Z.

In embodiments the applicators/plasma sources of the reactor are preferably configured to operate at a microwave frequency f in the range of 300 MFIz to 6000MFIz. It is understood that different applicators may be operated at different frequencies.

The invention is also achieved by a method to fabricate synthetic films, preferably thick films of hard materials, more precisely diamond films. The films provided by the invention may have a complex shape and/or having at least one through aperture that may have another shape than the outer shape of the deposited film. Methods of the invention allow also to realize at least one hard layer, such as a diamond layer, on at least a portion of at least one complex shaped substrate.

The thickness range of diamond film is from 0.1 to 500pm, but typically 1 to 100pm

More precisely the method of the invention comprises the following steps.

In embodiments the method for producing synthetic material on a substrate by microwave plasma activated chemical vapor deposition comprises the steps of:

- providing a CVD reactor as described above, comprising a chamber with a substrate holder therein, said chamber and substrate holder being, a multitude of elementary microwave plasma sources configured to produce a coating on a substrate having a 2D or a 3D shape; the coating may be a homogenous or non-homogenous coating, or may be a composite hybrid coating as described above

- introducing a substrate having a specific geometrical shape into the chamber of the reactor and adapting said substrate on said substrate holder; In function of the geometrical shape the substrate may be positioned in a predetermined position or orientation.

- introducing process gases into said chamber, the process gases comprising at least hydrogen and a carbon precursor;

- realizing a film preferably of diamond on at least a portion of said substrate.

In an embodiment of the method the sample may be rotated. Such a rotation may be made continuously or in steps, or the orientation may be performed between different coating steps. For example, in a first position a ring-shaped coating may be applied on the sample. The sample is then repositioned or reoriented or turned according to a predefined angle and then in a second step a second coating is applied on a second portion of the sample. Such a variant allows to provide coatings on all surfaces of a sample, or provide different coatings on different surfaces of a sample. For example, a watch component may be completely coated with a SiC or diamond layer and is then subsequently repositioned so as to provide a second coating on one of its surfaces so as to provide a color effect on at least a portion of that surface. The color effect is given by an interferential effect which depends both on refractive index and thickness of each layer.

In an embodiment of the method the radius of curvature of the support plate of the applicators may be modified before, during or after the deposition process. For example, at a first stage of the process the radius may be R and it may be changed to another radius R’, by steps or in a continuous way.

In an embodiment said substrate is a flat substrate that may comprise holes or mesas.

In a preferred embodiment said substrate has a 3D form. Advantageously said substrate is a hollow ellipsoid or a hollow polyhedron.

In an embodiment the shape of the substrate is an elliptical ring. The shape of the substrate may also be a polygonal ring.

In an embodiment the shape of the substrate is a hollow ellipsoid (elliptical torus). The shape of the substrate may also be a hollow polyhedron.

In an embodiment of the method the material is chosen among Diamond (C), SiC, CN, B4C or a combination of them. In an embodiment of the method the material of the substrate is chosen among Si, SiC, Si3N4, silicon derivatives, diamond, CB, CN, refractory metals and their derivatives, titanium and titanium-based alloys, cemented carbides, ceramics, oxides such as fused silica or alumina or a combination of them.

In an embodiment of the method the material of the substrate is made of any material covered with a thin layer of another material chosen among Si, SiC, Si3N4, silicon derivatives, diamond, CB, CN, refractory metals and their derivatives, titanium and titanium-based alloys, cemented carbides, ceramics, oxides such as fused silica or alumina or a combination of them.

In an embodiment of the method the applicators of the reactor operate at a microwave frequency f in the range of 300 MHz to 6000MHz.

In embodiments the combination of the predetermined arrangement of plasma applicators and/or their sizes and/or their movements and/or their frequencies allows to obtain coating effects and properties that may not be realized by any of prior art reactors and/or or deposition methods or uses.

In other embodiment, the material of coating can be changed in the deposition process by changing the inlet gas composition. A multilayer or a graded layer is thus formed.

In other embodiment, the composition of the coating can be changed on the substrate by a multistep process in which, in a first step, an arrangement of plasma sources is switched on with a first gas composition and a second step a different arrangement of plasma sources is switched while the first one is switched off, a second gas composition is inlet in the reactor.

In other embodiment, the thickness of the coating is locally varied on the substrate by adjusting the distance of the plasma source from the substrate surface and/or by adjusting the microwave power on each individual plasma source.

In an advantageous embodiment the reactor of the invention 1 may be configured so that different plates (defined as applicator holders or frames) comprising predefined patterns of holes or holder may be inserted and exchanged in the reactor. This is explained further in the method section. For example, for a first coating an annular coating has to be provided and a plate comprises apertures and applicators arranged on a circle. In a second coating step a triangular shaped coating has to be provided. In that case the first plate configured to provide an annular coating is removed from the reactor and a plate configured to provide a triangular coating is inserted in the reactor. In variants such a first and second coating step may be provided onto the same substrate.

The invention is also achieved by the use of the reactor of the invention as described above, for realizing a diamond film having a complex shape and /or depositing diamond film on at least a portion of an substrate or object having a 2D or a 3D shape, said shapes of the film and/or substrate being described above.

The invention is also realized by coated components by the reactor and the method of coating as described above. Some typical examples of coated components are:

- horology components;

- medical components;

- industrial parts such as parts of a machine;

- mechanical components;

- optical components;

- mems samples

It is understood here that there are no limitations on the 2D and/or 3D shapes and sizes of the samples to be coated samples. Also, a mini table-top reactor of the reactor may be provided to realize very small parts such as medical tips or watch components. On the other hand, the reactor may have a great volume to coat samples having large diameters and/or thicknesses such as a diameter of more than 50cm. The reactor may be a hybrid reactor that is suitable to coat large dimensional pieces and at the same time or in sequence suitable to coat small parts, may be a small part on said piece having a large dimension.

Examples of realization methods and coated samples 1000-5000

Samples 1000-5000 may be realized that present a central hole In a first example,

1. A substrate 2000 (Fig.13) is an elliptical ring made in silicon nitride having dimensions R21 = 50mm, R22 = 200mm, R23 = 90mm and R24 = 300mm (Figure 2). Its thickness is 5mm; The substrate has a central aperture 2002 2. The substrate 1000 is placed in a CVD reactor of the invention wherein 56 coaxial applicators are placed to follow the elliptical shape of the substrate to achieve a good coating uniformity;

3. A gas mixture composed of methane and hydrogen is introduced in the chamber and a pressure of 1 mbar is regulated;

4. Each coaxial applicator is supplied at 250 W of microwave power at a frequency of 2.45GHz. The total power is 14 kW in the chamber.

5. A nanocrystalline diamond coating of lpm on the elliptical shape substrate is obtained after 10 hours of deposition.

In a second example,

1. A substrate 1000 being a circular ring made in silicon is provided, having dimensions R1 = 400mm and R2 = 600mm Its thickness is 2mm.

2. The substrate 1000 is placed in CVD reactor wherein 60 coaxial applicators are placed in several concentric circles to follow the annular shape of the substrate to achieve a good coating uniformity;

3. A gas mixture composed of methane, oxygen and hydrogen is introduced in the chamber and a pressure of 5 mbar is regulated

4. Each coaxial applicator is supplied at 600 W of microwave power at a frequency of 915MHz. The total power is 36 kW in the chamber.

5. A microcrystalline diamond coating of 30pm is obtained after 75 hours of deposition.

In a third example (illustrated in Fig.15) ,

1. A substrate 4000 being an elliptical torus made in titanium alloy is provided, and having dimensions R41 = 350mm, R22 = 500mm, R43 = 400mm and R44 = 550mm (Figure 15). Its thickness T4 is 75mm.

2. The substrate 4000 is placed in CVD reactor 1 where 50 coaxial applicators are placed on the top base of reactor to follow the ellipsoid shape of the substrate. A series of 24 coaxial applicators are places in each side of the tore. This three dimensional matrix allows us to achieve a good coating uniformity.

3. A gas mixture composed of methane, oxygen and hydrogen is introduced in the chamber and a pressure of 2 mbar is regulated

4. Each coaxial applicator is supplied at 400 W of microwave power at a frequency of 915MHz. The total power is 39 kW in the chamber. 5. A microcrystalline diamond coating of 9pm is obtained after 30 hours of deposition.

Fig.16 illustrates another coated sample 5000 having hexagonal cross-sections and a central aperture 5002.

Claims

1. A microwave plasma reactor (1) for manufacturing components comprising a synthetic layer made of a hard material via chemical vapor deposition, comprising:

- a plasma enclosure (2) comprising a base plate (102), a top plate (108) and a side wall (104, 106) extending from said base plate (102);

- one or several plasma sources (100) comprising at least one microwave generator (100’) configured to generate microwaves in said plasma enclosure (2) ;

- an array (10) of plasma applicators (100’”), each associated to at least one of said microwave generators (100’) , having an output dielectric window (100^IV, 100a-100n) to the side of said plasma enclosure (2) and suitable to generate each a localized plasma in the plasma enclosure, said dielectric windows being positioned in the plasma enclosure according to a pattern defined by a border described by a predetermined polygon.

- a gas flow system (130), comprising at least one gas inlet (131), for feeding process gases into the plasma enclosure (2) and removing them therefrom; a substrate holder (120) defining an area to adapt a substrate (1000, 2000, 3000, 4000, 5000) ;

2. The microwave plasma reactor '(1) according to claim 1 wherein at least one of said plasma sources (100) are configured to be activated or deactivated during the operation of the reactor (1).

3. The microwave plasma reactor (1) according to claim 1 or claim 2 wherein said predetermined pattern is a fixed pattern.

4. The microwave plasma reactor (1) according to any one of claims 1 or claim 3 comprising at least one channel (112) , having a predetermined shape, for moving at least one applicator along said channel (112).

5. The microwave plasma reactor (1) according to any one of claims 1 to 4, comprising at least two plasma chambers (la, lb) that are in gaseous communication.

6. The microwave plasma reactor (1) according to any one of claims 1 to

5, comprising a central cylindrical wall (140) .

7. The microwave plasma reactor (1) according to any one of claims 1 to

6, wherein at least one of said applicators (100) can be moved and/or reoriented in 3D inside the plasma enclosure (2).

8. The microwave plasma reactor (1) according to any one of claims 1 to

7, wherein the reactor may be operated at temperatures higher than 400° C.

9. The microwave plasma reactor (1) according to any one of claims 1 to

8, wherein material deposited on the substrate is chosen among Diamond (C), SiC, CN, B4C, Si3N4, amorphous carbon or a combination of them.

10. The microwave plasma reactor (1) according to any one of claims 1 to

9, wherein at least two of the output dielectric windows (100^IV, 100a-100n) have a different distance relative to the wall (102, 104, 106, 108) in which the plasma applicators (100’) are arranged.

11. A method of fabrication of coated samples comprising the steps of :

- providing a reactor (1) according to any of claims 1 to 10 and comprising an array of plasma applicators (100’”);

- activating a predetermined number n of plasma applicators so as to provide a predetermined shape of a plasma inside said enclosure (2);

- realizing a coating having a predetermined shape and predetermined properties on a sample (1000) present in said plasma enclosure (2).

12. The method of fabrication according to claim 11 comprising the steps of:

- providing a reactor (1) comprising at least one translatable plasma applicator (100”’) arranged into or onto a channel (121) of a plate of the reactor (1); - activating said translatable plasma applicator (100’”);

- moving said translatable plasma applicator (100’”) along said channel

(121) ;

- realizing a coating having a predetermined shape and predetermined properties on a sample(1000-5000) present in said plasma enclosure

(2).

13. The method of fabrication according to claim 12 wherein the translatable plasma applicator (100”’) is moved according to a predetermined speed time scheme. 14. The method of fabrication according to any one of claims 11 to 13 comprising the steps of:

- providing a reactor (1) according to any one of claims 5 to 10 and comprising at least two plasma chambers (la, lb);

- realizing surface treatments on a sample (1000-5000) successively in said at least two plasma chambers (la, lb), at least one of said surface treatments being the deposition of a hard coating, preferably a diamond coating.

15. Method of fabrication according to any one of claims 11 to 14, wherein the deposition process is done at temperatures higher than 400° C. 16. Method of fabrication according to any one of claims 11 to 15, wherein material deposited on the substrate is chosen among Diamond (C), SiC, CN, B4C, Si3N4, amorphous carbon or a combination of them.

17. Use of the microwave plasma reactor (1) according to any one of claims 1 to 10 to realize coated samples comprising a hard coating layer.

18. A sample comprising a hard coating layer realized in a microwave plasma reactor (1) according to any one of claims 1 to 10 and with the method according to claims 11 to 16.