FR3073864A1 - LAYER DEPOSITION REACTOR AND ASSOCIATED DEPOSITION METHOD - Google Patents

Abstract

The present invention relates to a reactor (10) for depositing layers on a substrate (22) to be coated, the reactor (10) obtaining at least one layer of the spray deposition of a target (20) on the substrate, the reactor ( 10) comprising: - a first source (14) capable of emitting electromagnetic waves, the first source (14) being able to excite the plasma (P) between the target (20) and the substrate (22), and - a second source (16) adapted to emit electromagnetic waves, the second source (16) being adapted to excite the target (20).

Description

The present invention relates to a coating for a device and to a device comprising such a coating.

In thermal solar applications, solar radiation is used to heat a heat transfer fluid, such as water, air, oils or molten salts. For example, the hot fluid thus obtained is used directly as in the case of a water heater. As a variant, the hot fluid is used directly, or transmits its heat to a second fluid, to drive a steam or gas turbine which generates electricity as in the case of a concentrated solar power plant.

In each case, the heat transfer fluid circulates inside pipes or plates which must first be heated by solar radiation, to then transmit this heat to the fluid. These elements, pipes or plates, thus constitute the body of the solar receivers. These elements are generally made of metal.

However, metals reflect visible radiation and infrared radiation. To obtain high capture efficiency in solar thermal systems, metal surfaces must therefore be functionalized to make them absorbent in the range extending from 280 nanometers (nm) to 2500 nm of the solar spectrum.

To achieve such an objective, thin absorbent layers can currently be deposited on these metal surfaces, either by vacuum processes (physical vapor deposition designated by the acronym PVD, chemical vapor deposition assisted by plasma under the acronym PECVD) , from solid targets, precursors, or mixtures of precursors, gaseous or liquid, containing the constituent elements of the deposits, either by soft chemistry (sol-gel). The solar absorptivity of the a _s receptor can thus reach 95 to 96%.

In addition, solar receivers work in temperature, from 100 to 1000 ° C depending on the technologies and applications (heat or electricity). The solar receivers can thus lose thermal energy by radiative exchanges with the ambient medium, losses all the more important as the solar receiver is hot (law of StefanBoltzmann in σΤ ⁴ ). To limit these radiative losses, it is necessary to ensure that the infrared emissivity of the receivers is not too high, that is to say that the receivers have a high reflectivity in the infrared. This property, already intrinsic to metals, can be improved by surface treatments on the receptor by depositing, by the same techniques as those mentioned above, pure metals naturally less emissive than the alloy constituting the receptor and which have better surface condition. A thermal emissivity <T) of less than 10% at

400 ° C, or less than 15% at 600 ° C, is typically sought.

For this, the solar receivers are conventionally coated by stacks of thin layers of different nature, which give the receiver a spectral selectivity character, that is to say that their optical behavior is different depending on the wavelength received: solar receivers absorb strongly in the solar range (weak reflection) and emit little in the infrared (strong reflection), thus coupling the two properties mentioned above.

In thermal solar applications, these selective coatings have long been used. The coatings are generally composed of multilayers, comprising an infrared reflective metal (low emissivity), a tandem of metal / ceramic solar absorbent composites with different metal contents, where the ceramic is sometimes an oxide or a nitride of the metal, and an anti-reflective layer. of this same transparent ceramic. The following pairs are, for example, known: inox-AIN, (Mo, W) -Si0 ₂ , (Mo, W) -AI ₂ 0 ₃ .

However, the use of such selective coatings currently available is limited by their low resistance to oxidation at high temperature, which sometimes requires them to be used under vacuum, leading to high technological constraints, high production costs and low durability. Indeed, the coated metal absorber must be protected by a glass tube in which the vacuum is created during the manufacture of the receiver, and the very different thermal expansions of glass and metal must be accommodated by special technologically complex bellows and expensive, in order to effectively maintain the vacuum during operation in the sun. Indeed, the loss of vacuum leads to the destruction of the coating and the receiver is then to be replaced, which induces high maintenance and operating costs.

There is therefore a need for a coating for a device which makes it possible to obtain better properties than known coatings.

To this end, the description describes a coating for a device, the coating being a stack of layers, at least one first layer having a thickness less than or equal to 200 nanometers, the first layer being made of a first material, the first material comprising silicon carbide, the atomic ratio between silicon and carbon being strictly less than 1.

According to particular embodiments, the coating comprises one or more of the following characteristics, taken alone or according to any technically possible combination:

each layer has a thickness less than or equal to 200 nanometers.

- the first material comprises at least one additional element, the first material verifying at least one of the following properties:

- a first property according to which the additional element is nitrogen, the atomic nitrogen content being between 0 and 40%,

- a second property according to which the additional element is oxygen, the atomic oxygen content is between 0 and 40%,

a third property according to which the additional element is hydrogen, the atomic hydrogen content is between 10% and 30%, and

- a fourth property according to which the additional element is a metal.

- in the first material, the atomic ratio between silicon and carbon is strictly greater than 0.2.

- the stack of layers is a set of bilayers, each bilayer comprising a metal layer and a first layer.

- Each metal layer is made of the same metal, the metal preferably being a refractory metal, a transition metal or a noble metal.

the stack comprises a second layer, the second layer being made of a second material, the second material comprising silicon carbide and optionally one or more elements chosen from hydrogen, nitrogen, oxygen or a metal, an optical index being defined for each material, the optical index of the second material being strictly less than the optical index of the first material.

- The stack comprises a third layer, the third layer being a metallic layer.

A device is also proposed, in particular a heat engine or solar receiver, comprising a coating as previously mentioned.

According to a particular embodiment, each layer has a thickness and each layer is made of a respective material having an optical index, the device being a solar receiver having a set of parameters among which each thickness and each optical index and in which the receiver solar has a yield, the yield being defined as the ratio between the solar radiation actually absorbed by the solar receiver less thermal losses and the solar radiation received by the solar receiver, the yield depending on the set of parameters, the thicknesses and the optical indices being chosen so that the efficiency of the solar receiver is greater than or equal to 70% of the maximum efficiency obtained by varying only the thicknesses and the optical indices, preferably greater than or equal to 90% of the maximum efficiency obtained by varying only the thicknesses and indic es optics.

Furthermore, the description describes a reactor for depositing layers on a substrate to be coated, the reactor obtaining at least one layer of the deposit by spraying a target on the substrate, the reactor comprising a first source capable of emitting electromagnetic waves, the first source being suitable for exciting the plasma between the target and the substrate, and a second source suitable for emitting electromagnetic waves, the second source being suitable for exciting the target.

According to particular embodiments, the reactor comprises one or more of the following characteristics, taken alone or according to any technically possible combination:

the reactor is capable of operating according to two operating modes, a first operating mode in which the reactor is capable of obtaining at least one layer of the deposit by spraying a target on the substrate and a second operating mode in which the reactor is capable of obtaining at least one layer of the deposit by a chemical vapor deposition assisted by plasma from a gaseous or liquid precursor.

the reactor has a chamber, a chamber pressure controller in the reactor, the controller being able to decrease or increase the pressure in the chamber to switch from one operating mode to another operating mode.

- at least one of the following properties is verified:

a first property according to which the first source is capable of emitting electromagnetic waves having a frequency between 1 gigahertz and 100 gigahertz,

a second property according to which the second source is capable of emitting electromagnetic waves having a frequency between 1 megahertz and 400 megahertz, and

- a third property according to which each source is distinct.

- the first source comprises at least one pencil provided at one end with a magnet.

- The reactor further comprises a third source suitable for emitting electromagnetic waves, the third source being suitable for exciting the substrate to be coated.

- the third source is capable of emitting electromagnetic waves having a frequency between 30 kilohertz and 3 Megahertz.

A method of depositing layers on a substrate to be coated is also proposed, using a reactor comprising a first source capable of emitting electromagnetic waves, the first source being capable of exciting a plasma between the target and the substrate, and a second source suitable for emitting electromagnetic waves, the second source being suitable for exciting the target. The method comprises a phase of depositing a layer by spraying a target onto the substrate, the phase comprising at least the steps of generating a plasma between the target and the substrate by the generator, excitation by the first source of the plasma by emitted electromagnetic waves, and excitation by the second source of the target by emitted electromagnetic waves.

According to a particular embodiment, the method comprises a phase of depositing a layer by chemical vapor deposition assisted by plasma from a gaseous precursor or evaporated liquid, using the reactor.

Other characteristics and advantages of the invention will appear on reading the following description of embodiments of the invention, given by way of example only and with reference to the drawings which are:

- Figure 1, a schematic view of an example of coating;

- Figure 2, a schematic view of another example of coating;

- Figure 3, a schematic view of yet another example of coating, and

- Figure 4, a schematic representation of an example of a reactor for obtaining a coating according to Figures 1,2 or 3.

With reference to FIGS. 1, 2 and 3, examples of coating for devices are proposed.

The coatings have in common that they are a stack of layers. The number of layers varies between 2 and several hundred.

At least one first layer having a thickness less than or equal to 200 nanometers.

The first layer is made of a first material, the first material comprising silicon carbide. The crystalline silicon carbide SiC is a semiconductor, absorbing in the visible.

For the first material, the atomic ratio between silicon and carbon being strictly less than 1.

Preferably, the atomic ratio between silicon and carbon in the first material is strictly greater than 0.2.

Preferably, the atomic ratio between the silicon and the carbon of the first material is strictly less than 0.5.

Advantageously, each layer has a thickness less than or equal to 200 nanometers.

According to an example, the first material comprises at least one additional element, the additional element is nitrogen, the atomic content (stoichiometry) of nitrogen being between 0 and 40%.

According to another example or in addition, the first material comprises at least one additional element, the additional element is oxygen, the atomic oxygen content being between 0 and 40%.

According to yet another example or in addition, the first material comprises at least one additional element, the additional element is hydrogen, the atomic hydrogen content is between 10% and 30%.

According to a fourth example, the additional element is metal.

In particular, the metal is inserted in the form of inclusions having a nanometric size so as to form a nanocermet.

In one embodiment, the stack of layers is a set of bilayers, each bilayer comprising a metal layer and a first layer.

Each metal layer is made of the same metal.

For example, the metal is a refractory metal with a relatively high melting point, for example greater than 2000 ° C.

By way of illustration, the refractory metal is W or Mo.

Such a coating is particularly suitable for applications at high temperature, typically more than 400 ° C.

According to another example, the metal is a transition metal.

For example, the transition metal is Al, Ti or Ni.

Such a coating is particularly suitable for applications at a lower temperature, typically less than 300 ° C.

According to yet another example, the metal is a noble metal.

As an illustration, the noble metal is Au or Ag.

Such a coating is particularly suitable for applications involving high visible / solar absorption at low temperature (typically less than 100 ° C) or at room temperature.

In some cases, the stack comprises a second layer, the second layer being made of a second material, the second material comprising silicon carbide and optionally one or more elements chosen from hydrogen, nitrogen, oxygen or a metal, an optical index being defined for each material, the optical index of the second material being strictly lower than the optical index of the first material.

In addition, the stack has a third layer, the third layer being a metallic layer.

The examples of Figures 1 to 3 are specific examples of the previous cases.

The stack in FIG. 1 illustrates the case of a stack with a metal / ceramic multilayer absorber.

More precisely, the stack of FIG. 1 comprises a substrate S (metallic or other) then a thin functional layer C1 (for example a bonding layer, a diffusion barrier or an infrared reflector) then a thin metallic layer C2 ( for example W) then a ceramic thin layer C3 (for example SiC (N, O, H)) then again a metallic thin layer C4 and a ceramic thin layer C5 and a functional thin layer C6 (for example, an antireflective ceramic layer optical and / or low mechanical friction).

The stack in FIG. 2 illustrates the case of a stack with a metal / ceramic composite absorber.

More precisely, the stack of FIG. 2 comprises a substrate S (metallic or other) then a functional thin layer C1 (for example a bonding layer, a diffusion barrier or an infrared reflector) then a first thin metal composite layer -ceramic C7 having a first inclusion rate, then a second thin metal-ceramic composite layer C8 having a second inclusion rate distinct from the first inclusion rate and a functional thin layer C6 (for example, an optical anti-reflective ceramic layer and / or low mechanical friction).

The stack in FIG. 3 illustrates the case of a stack with a periodic metal / ceramic bilayer.

More specifically, the stack of FIG. 3 comprises a substrate S (metallic or other) then a functional thin layer C1 (for example a bonding layer, a diffusion barrier or an infrared reflector) then a series of stacked bilayers B , each bilayer B comprising a thin metallic layer C1 (for example

W) then a thin ceramic layer C2 (for example SiC (N, O, H)). The stack of FIG. 3 also includes a functional thin layer C6 (for example, an optical anti-reflective ceramic layer and / or of low mechanical friction).

The coating thus has a selective solar character: high solar absorptivities of around 90% and low thermal emissivities of around 20% at 500 ° C.

The coating can therefore be advantageously used for solar collection purposes and makes it possible to obtain a device coated with the coating having a very good collection efficiency at high temperature thanks to the high solar absorptivity of the coating and the low infrared emissivity of the coating.

The coating has good thermomechanical properties.

The coating is also designed to resist oxidation at high temperatures, and therefore has the enormous advantage of operating in air compared to existing coatings. Otherwise formulated, the coating does not imply maintenance under vacuum, which makes the coating simple to implement technologically. This results in easier maintenance since the durability of the coating is increased.

Because of its many properties, the coating can be used for many applications, namely for the mechanical, automotive, space industry (as hard coating, anti-wear or anti-friction), in military applications (for invisibility infrared), in the building sector (coating favoring radiative cooling), in the optical and photovoltaic industry (as anti-reflective, anti-scratch, reflective layers) or in the concentrated solar industry, as reflective layers resistant to abrasion for concentrating mirrors, or as selective layers for cooling.

The coating can thus be used for a device such as a heat engine or solar receiver.

In the latter case, it should be noted that the coating, and in particular the thicknesses of the layers, can be optimized by choosing an optimization target such as the highest possible solar absorption, or better, the conversion efficiency of solar radiation / highest possible heat. Such optimization can be done with optical simulation software, such as CODE® (COating DEsigner).

For example, each layer has a thickness and each layer is made of a respective material having an optical index, the device being a solar receiver having a set of parameters among which each thickness and each optical index and in which the solar receiver has an efficiency , the efficiency being defined as the ratio between the solar radiation actually absorbed by the solar receiver less thermal losses and the solar radiation received by the solar receiver, the efficiency depending on the set of parameters, the thicknesses and the optical indices being chosen so that the efficiency of the solar receiver is greater than or equal to 70% of the maximum efficiency obtained by varying only the thicknesses and the optical indices, preferably greater than or equal to 90% of the maximum efficiency obtained by varying only the thicknesses and indices optics.

To understand such a definition of the efficiency of the solar receiver, it is necessary to define spectral values of reflectivity R (/ L) and transmittivity T (A) of the surface of a material, measurable quantities to deduce its spectral absorptivity A ( A) - 1 R (X) - T (À), as well as two total values (independent of the wavelength) representative of the optical behavior of the material, used to determine the effectiveness of selective coatings:

- the solar absorbance as, a function of the solar spectrum G (2), given by the ratio between the flux density actually absorbed by the material and the incident solar flux density I. A high solar absorbance coefficient Os corresponds to a high solar absorption.

0.28 · G (Â) dÀ _ Density of flux absorbed by the material (W / m ² )

Incident solar flux density (W / m ² )

- the thermal emittance ¢ (7) at temperature T, a function of the emission spectrum of the black body P (Â, T) (Planck's law), given by the ratio between the flux density actually emitted by the material and the flux density that would be emitted by an ideal black body at the same temperature (maximum emission). ¢ (7) represents the overall capacity of the material to emit radiation when it is hot. Reducing radiative heat losses therefore amounts to reducing ¢ (7).

These two quantities make it possible to calculate the so-called “solar thermal” efficiency, that is to say the efficiency of conversion of concentrated solar radiation (with a concentration factor C) into heat, that is to say concentrated solar radiation that it actually absorbs (a _s .CI), minus the radiative losses (Stefan-Boltzmann ¢ law (7) .σΓ ¹ ), on the concentrated solar radiation it receives (C. /). It is this yield which must be optimized, by increasing a _s and by decreasing ¢ (7).

a _s C Ie (T) aT ⁴ ε (Τ) · σΤ ⁴ η Φζ ^l) ______________ ^v '________ ₌ / y • solar thermal ▼ S

THIS

However, such coatings, and in particular the case of composite metal-ceramic or two-layer coatings comprising a metal layer and a first layer, are difficult to obtain.

The reactor 10 illustrated in FIG. 4 is a reactor allowing a person skilled in the art specialized in the field to obtain such a coating.

The reactor 10 is a layer deposition reactor on a substrate 22 to be coated.

The reactor 10 is capable of operating according to two operating modes, a first operating mode in which the reactor 10 is capable of obtaining at least one layer of the deposit by spraying a target on the substrate 22 (PVD technique) and a second operating mode in which the reactor 10 is capable of obtaining at least one layer of the deposit by a chemical vapor deposition assisted by plasma from a gaseous precursor or evaporated liquid (PECVD technique).

A reactor 10 capable of operating according to two operating modes is advantageous insofar as the PVD and PECVD techniques are complementary.

The PVD technique is relatively simple to implement and well suited for depositing on large areas. The technique consists in bombarding a target 20 with the energetic ions of a plasma subjected to an excitation frequency, so as to extract atoms from it to deposit them on a substrate 22. The PVD technique makes it possible to act on the microstructure of the thin layer by applying a polarization on the substrate 22 to be coated, and thus densify the deposited material to increase in particular the resistance to oxidation (penetration of ambient oxygen more difficult in a dense material). The main shortcoming of this sputtering technique lies in obtaining low deposition rates, thus increasing the processing times and the manufacturing costs. In fact, the plasma excitation frequency used (direct current (DC), low frequency (BF 50-500 kHz) or radiofrequency (RF, a few MHz)), which is used to extract electrons from the gas atoms to generate the plasma , results in a low electronic density (less than 10 ¹ ° cm ' ³ ). Consequently, the concentration of ions sputtering the target is low, inducing a low deposition rate. In order to obtain denser plasmas causing greater sputtering of the target and higher deposition rates, the magnetron configuration is often used: the electrons from the ionization of the plasma gases are then confined around the sputtering target thanks magnets, locally increasing the density of the plasma and the associated sputtering. A disadvantage of this magnetron configuration is that the plasma, and therefore the wear of the target, are inhomogeneous because they follow the lines of magnetic fields of the magnets, and it is often not possible to spray more than a third of the target, which results in high operating costs (significant material cost). The PVD technique is however well suited for depositing conductive materials such as metals, from a metal target immersed in a plasma of neutral gas (such as argon). Indeed, the conductive nature of the target allows the application of a direct current on the target to generate the spray plasma.

The PECVD technique, based on the plasma activation of reactions between gaseous precursors or an evaporated liquid, from ambient to 500 ° C, makes it possible to synthesize ceramics. The PECVD technique also makes it possible to deposit ceramics with great mastery of the substrate-deposit interfaces and especially of the composition. The precursors comprising the elements to be deposited are diluted in a plasma gas such as argon. A plasma of this mixture is generated by excitation with an electromagnetic field. Only one excitation mode is most often used in PECVD. It is a field directly applied to the substrate 22 to be coated. Thus, the electrons of the generated plasma collide with the gaseous precursors to form reactive, energetic or neutral species which are deposited on the surface and form the film. Electrons also tend to accumulate on the surface to be coated because they are the only plasma species small enough to follow the rapid oscillations of the applied electric field. Positive plasma ions are attracted by this negative voltage (self-polarization) to the surface to be coated and bombard the deposit being grown. This ion bombardment can have a beneficial effect on the deposited layer, by making it possible to adjust the microstructure and the composition of the material (densification, selective spraying of chemical environments. But it also leads to a natural heating of the parts to be coated. it is not possible to independently control the temperature of the treated surface, nor to treat sensitive parts at low temperature (eg polymers). On the other hand, in this configuration where only one excitation mode is applied to the surface to be coated, the power densities necessary for maintaining the plasma are very high (of the order of 0.2 - 0.6 W / cm ² ). This is unacceptable for the transition to industrial scale because the powers required and the costs of associated manufacturing are considerable when one wants to coat large surfaces. Finally, to deposit organosilicon ceramics SiC (N, O, H) in PECVD, l he ceramic precursor is often a gaseous mixture based on silane SiH ₄ , associated with CH ₄ and / or NH ₃ and / or O ₂ , depending on the composition sought. Silane is however a toxic and extremely flammable gas, requiring high and costly safety levels.

The reactor 10 capable of operating according to two operating modes therefore makes it possible to produce metal and ceramic bilayers.

The reactor 10 comprises a first source 14, a second source 16 and a third source 18.

A plasma is generated by at least one source from the previous sources so that it (s) generally acts as a plasma generator 12. Preferably, the first source 14 is used.

The first source 14 is capable of emitting electromagnetic waves, the first source 14 being capable of exciting a plasma P between the target 20 and the substrate 22.

The first source 14 is capable of emitting electromagnetic waves having a frequency between 1 gigahertz and 100 gigahertz.

The first source 14 comprises a microwave generator 24, a power distributor 26 and a plurality of pencils 28 each provided at one end with a magnet 30.

In the example illustrated, four pencils 28 are shown in FIG. 4.

The second source 16 is distinct from the first source 14.

The second source 16 is capable of emitting electromagnetic waves, the second source 16 being capable of exciting the target 20.

The second source 16 is capable of emitting electromagnetic waves having a frequency between 1 megahertz and 400 megahertz.

The third source 18 is distinct from the first source 14 and the second source 16.

The third source 18 is capable of emitting electromagnetic waves, the third source 18 being adapted to excite the substrate 22 to be coated.

The third source 18 is capable of emitting electromagnetic waves having a frequency between 30 kilohertz and 3 Megahertz.

In FIG. 4, other elements of the reactor 10 are represented as a vacuum enclosure 32, a pumping system 34 of which only one pipe is shown for simplicity, a gas injector 36 controlled by flow regulator (s), a substrate carrier system 38, optionally heating (rear face) and / or rotary and / or polarizable by the third generator 18, a removable shutter 40, a cathode 42 (optional magnetron) cooled.

The operation of the reactor 10 is now described with reference to a process for depositing layers on a substrate 22 to be coated using the reactor 10.

The method includes a phase of depositing a layer by sputtering a target 20 on the substrate 22.

The spray deposition phase has three excitation steps.

An excitation step is the excitation by the first source 14 of the plasma P between the target 20 and the substrate 22 by electromagnetic waves.

More specifically, the rods from the first source 14, distributed over the walls of the reactor 10, are equipped with magnets which confine the most energetic electrons of the plasma P on their magnetic field lines. The P plasma is thus produced around the sources (by inelastic collisions of fast electrons on the atoms and molecules of the gas), then diffuses out of the production zone under the effect of the density gradients. The microwaves do not have to propagate in the reactor 10 and the diffusion plasma P is much more stable, homogeneous and dense, in particular around the target 20, than in a conventional magnetron configuration.

Another excitation step is the excitation by the second source 16 of the target 20 by electromagnetic waves.

The ions from the plasma P are then attracted by the negative polarization applied separately to the target 20. The coupling with the first source 14 makes it possible to ensure a much more homogeneous sputtering and wear of the target 22 than in a conventional magnetron configuration (and thus avoiding wasting the raw material and reducing manufacturing costs).

Yet another excitation step is the excitation by the third source 18 of the substrate 22.

Such an excitation step can lead, by ion bombardment, to the densification of the films or to the control of their chemical composition, having a direct impact on their properties, in particular optical, mechanical and thermal stability.

In other words, during the spray deposition phase, at least two parameters can thus be decoupled and managed separately, unlike conventional methods based on a single excitation mode: on the one hand, generation (around micro- waves) and the maintenance of electrons and ions in volume in the homogeneous phase of the discharge, are ensured by microwave excitation and on the other hand, the control of the impact energy of the ions on the target 20 , managing the spraying efficiency, is ensured by the other excitation. Since the plasma P is generated in volume and no longer only around the target 20, the wear on the target 20 is much more homogeneous and the material costs are reduced.

Optionally, the application of a third excitation on the substrate 22 to be coated can make it possible to more precisely adjust the optical, mechanical and thermal stability properties of the materials produced.

The PVD deposition phase is particularly suitable for the deposition of metal alone, the gas mixture injected by the injector 36 consisting of a pure plasma gas, the first and second sources 14 and 16 are switched on and the shutter 40 is open. .

As a variant, only the second source 16 is switched on instead of the two sources 14 and 16.

The method comprises a phase of depositing a layer by chemical vapor deposition assisted by plasma P from a gaseous precursor or evaporated liquid.

In this PECVD deposition phase, two separate excitation modes can be used. The first excitation mode comes from the first source 14 which generates and maintains the plasma P as well as the reactivity of the precursors in the plasma volume. The first source 14 thus gives access to much higher plasma densities P (»10 ¹ ° electrons / cm ³ ) than in the conventional PECVD configuration (<10 ¹ ° electrons / cm ³ ), making it possible to increase the speeds of filing and reduce production costs.

A second mode of excitation is also independently applied to the substrate 22 to be coated, to activate the surface reactivity and finely control the microstructure, the composition and the densification of the layers deposited by ion bombardment. The temperature of the surface to be coated is thus much better controlled due to the remote volume sources. In addition, the reactive plasma P being maintained in volume by the first source 14, and no longer on the substrate 22 to be coated, the power required for the deposition is no longer directly proportional to the size of the surface to be coated.

The transition from one phase to another is obtained by a chamber pressure controller in the reactor 10, the controller being able to decrease or increase the pressure in the chamber to switch from one operating mode to another. operating mode.

Indeed, in PVD the pressures are low (of the order of 10 ^-2 mbar to 10 ^-3 mbar) to increase the mean free path of the gaseous species, and thus facilitate the spraying of the target 20 and the diffusion of the evaporated species towards the part to be coated. In PECVD, the P plasma is reactive and the traditional production pressures are much higher (up to mbar) to favor chemical reactions and recombinations of species in plasma volume.

Alternatively, the method is implemented with a relatively small change in pressure between the two phases. In such a case, the rods 28 are suitable for low pressure, that is to say between 10 ^-2 mbar and 10 ^-3 mbar.

The PECVD deposition phase is particularly suitable for the deposition of ceramic only, the injected gas mixture consisting of a mixture of plasma gas and precursor (s), the first source 14 is switched on and the shutter 40 is closed.

Alternatively, the first source 14 and the third source 18 are turned on.

According to another variant, only the third source 18 is on.

The method makes it possible either to produce a stack of metal / ceramic multilayers by implementing the two PVD and PECVD phases successively or to deposit metal-ceramic composites, by implementing the two phases simultaneously.

The process makes it possible to obtain, in a controlled and efficient manner, the coatings 10 previously described.

The invention relates to the combination of all technically possible embodiments.

Claims (9)

1. - Reactor (10) for depositing layers on a substrate (22) to be coated, the reactor (10) obtaining at least one layer of the deposit by spraying a target (20) on the substrate, the reactor (10) comprising: a first source (14) capable of emitting electromagnetic waves, the first source (14) being capable of exciting a plasma (P) between the target (20) and the substrate (22), and - A second source (16) suitable for emitting electromagnetic waves, the second source (16) being suitable for exciting the target (20). 2, - Reactor according to claim 1, in which the reactor (10) is capable of operating according to two operating modes, a first operating mode in which the reactor (10) is capable of obtaining at least one layer of the spray deposit a target (20) on the substrate (22) and a second mode of operation in which the reactor (10) is capable of obtaining at least one layer of the deposit by a chemical vapor deposition assisted by plasma from an evaporated gaseous or liquid precursor. 3. - Reactor according to claim 2, in which the reactor (10) has a chamber, a controller of the pressure of the chamber in the reactor (10), the controller being able to decrease or increase the pressure in the chamber for tilting. from one operating mode to another operating mode. 4, - Reactor according to any one of claims 1 to 3, in which at least one of the following properties is verified: a first property according to which the first source (14) is capable of emitting electromagnetic waves having a frequency between 1 gigahertz and 100 gigahertz, a second property according to which the second source (16) is capable of emitting electromagnetic waves having a frequency between 1 megahertz and 400 megahertz, and - a third property according to which each source is distinct. 5. - Reactor according to any one of claims 1 to 4, wherein the first source (14) comprises at least one pencil (28) provided at one end with a magnet (30). 6. - Reactor according to any one of claims 1 to 5, in which the reactor (10) further comprises a third source (18) suitable for emitting electromagnetic waves, the third source (18) being suitable for exciting the substrate (22) to be coated. 7. - Reactor according to claim 6, wherein the third source (18) is adapted to emit electromagnetic waves having a frequency between 30 kilohertz and 3 Megahertz. 8. - Method for depositing layers on a substrate (22) to be coated using a reactor (10) comprising: a first source (14) capable of emitting electromagnetic waves, the first source (14) being capable of exciting a plasma (P) between the target (20) and the substrate (22), and - A second source (16) capable of emitting electromagnetic waves, the second source (16) being capable of exciting the target (20), the method comprising a phase of depositing a layer by spraying a target (20) on the substrate (22), the phase comprising at least the steps of: - excitation by the first source (14) of the plasma (P) between the target (20) and the substrate (22) by emitted electromagnetic waves, and - excitation by the second source (16) of the target (20) by emitted electromagnetic waves. 9. - Method according to claim 8, in which the method comprises a phase of depositing a layer by chemical vapor deposition assisted by plasma from a gaseous precursor or evaporated liquid, using the reactor ( 10).