Method for depositing a stack of thin layers by means of an ion beam, use of an ion beam and substrate obtained

Abstract

The invention relates to a method for depositing a stack of thin layers (14) on a face (11) of a glass substrate (10) by cathode sputtering, the stack of thin layers (14) including a silver-based metal functional layer (140, 180) deposited directly on a zinc oxide-based bottom layer (129, 169), the method including the use of an ion source, characterised in that the bottom layer (129, 169) is bombarded with ions during all or part of its deposition and has a biaxial texture: - an out-of-plane texture with an out-of-plane mosaicity of less than 15°; and - an in-plane texture with an in-plane mosaicity of less than 50°.

Description

METHOD FOR DEPOSITTING A STACK OF THIN LAYERS USING AN ION BEAM, USE OF AN ION BEAM AND SUBSTRATE OBTAINED

[0001] The invention relates to a method of depositing a stack of thin films on one face of a glass substrate by sputtering, said stack of thin films comprising a silver-based metallic functional layer deposited directly on a zinc oxide-based ground layer, said method comprising the use of an ion source.

[0002] The invention relates to the use of an ionic source for the deposition of this stack of thin films, the use of an ionic source and a glass substrate coated with this stack of thin films.

[0003] In the following description, the term "functional" qualifying "functional stacking" or "functional layer" means "able to act on solar radiation and infrared radiation".

[0004] Glazing incorporating such a substrate can be intended to equip both buildings and vehicles, with the aim of simultaneously: - reducing the effort of air conditioning and / or preventing excessive overheating, by producing a so-called "solar control" effect and - reducing the amount of energy dissipated to the outside while maximizing the entry of solar energy, by producing a so-called "low emissivity" effect.

[0005] Known selective glazing systems consist of transparent substrates coated with a functional stack comprising one or more metallic functional layers, each sandwiched between two dielectric or antireflective layers. Such glazing systems improve solar protection while maintaining high light transmission. These functional coatings are typically obtained through a series of depositions applied by sputtering, possibly assisted by a magnetic field.

[0006] The invention is particularly interested in substrates coated with a functional stack comprising one or more silver-based functional layer(s).

[0007] It is known, for example, from international patent applications No. WO 2005 / 00758, WO 2005 / 00759 and WO 2007 / 048963 to provide for the deposition of a stack of thin films on a substrate, said deposition process of the layers involving the use of an ion source.

[0008] The inventors discovered that it is possible to obtain a reduction in resistance per square of a silver-based functional layer of at least 10% and on the order of 12%, whether or not the stack undergoes heat treatment.

[0009] Indeed, the inventors discovered that a particular configuration of background layer, under a functional layer, made it possible to achieve this.

[0010] One aim of the invention is therefore to develop a new type of thin film stacking with one or more improved metallic functional layer(s).

[0011] The invention thus relates, in its broadest sense, to a method of depositing a stack of thin films onto a face of a glass substrate by sputtering, said face having a plane and said stack of thin films comprising a silver-based metallic functional layer deposited directly onto a zinc oxide-based ground layer, said method comprising the use of an ion source, said method being remarkable in that said ground layer is bombarded by ions during part or all of its deposition, and preferably only it, and exhibits a biaxial texture:

[0012] - an off-plane texture with an off-plane mosaic pattern that is less than 15°, and

[0013] - a texture in the plane with a mosaicism in the plane which is less than 50°, preferably less than 26°, or even less than 25°.

[0014] Mosaicity is the standard deviation of the distribution of grains; it expresses the alignment of the grains with each other.

[0015] Thus, thanks to this particular ground layer configuration, the metallic functional layer is textured in the plane by an epitaxial effect and therefore exhibits an improved crystallographic state. Advantageously, the present invention can lead to grains that are single crystals.

[0016] The said stack comprises one or more metallic functional layers and may comprise a single metallic functional layer, or two metallic functional layers, or three metallic functional layers, or four metallic functional layers; the metallic functional layers referred to here are preferably continuous layers.

[0017] A metallic functional layer preferably consists predominantly, at least 50% by atomic percentage: Ag; one, several, or each metallic functional layer is preferably silver.

[0018] For the purposes of this invention, "metallic layer" means a layer that does not contain oxygen or nitrogen.

[0019] As is customary, the term "dielectric layer" in the context of this invention means that, from the perspective of its nature, the layer is "non-metallic," that is, it contains oxygen or nitrogen, or both. In the context of this invention, this term means that the material of this layer has an n / k ratio over the entire visible wavelength range (from 380 nm to 780 nm) equal to or greater than 5.

[0020] It is recalled that n denotes the real refractive index of the material at a given wavelength and the coefficient k represents the imaginary part of the refractive index at a given wavelength, or absorption coefficient; the ratio n / k being calculated at a given wavelength identical for n and for k.

[0021] By "directly on" is meant, in the context of the invention, that no layer is interposed between the two layers considered.

[0022] For the purposes of this invention, "based on" means that, for the composition of this layer, the reactive elements oxygen, or nitrogen, or both if present, are not considered, and the non-reactive element (for example, silicon or zinc) indicated as constituting the base is present at more than 85% atomic percentage of the total non-reactive elements in the layer. This expression thus includes what is commonly referred to in this technique as "doping," whereas the doping element, or each doping element, may be present in quantities up to 10% atomic percentage, but without the total dopant exceeding 15% atomic percentage of the non-reactive elements.

[0023] By "biaxial texturing" in the sense of the invention, we mean that the texturing is observed along two axes: an axis, called "out of plane" which is perpendicular to the plane of the face on which the stack of thin layers is deposited and an axis which is located in the plane of the face on which the stack of thin layers is deposited.

[0024] In this document, the terminals are included within the indicated ranges.

[0025] In one particular variant, said ion bombardment is a bombardment of argon, xenon, helium, neon or krypton ions, or even dioxygen.

[0026] In one particular variant, said base layer is bombarded for 1 / 15 e at 3 / 4 of the deposition time of said base layer, in particular during 1 / 10 e at 1 / 2 of the deposition time of said base layer.

[0027] This partial-duration bombardment relative to the spraying is preferably carried out at the beginning of the spraying (discontinuous or continuous spraying).

[0028] The said bombardment is carried out, preferably, with an energy between 100 and 2,000 eV, in particular between 400 and 2,000 eV.

[0029] The said ion bombardment is carried out, preferably, at an angle of 45° plus or minus 30°, preferably plus or minus 15°, relative to the plane of said face of the substrate.

[0030] The said base layer can be deposited by reactive sputtering using a zinc metallic target or from a ZnO ceramic target, said target being pure but preferably doped with aluminium and / or tin, said doping by a single element or by all elements preferably being between 0.5 and 15.0 atomic % of the total metallic elements.

[0031] The said base layer preferably has a thickness between 1.0 and 80.0 nm, or even between 2.0 and 50.0 nm.

[0032] The said stack of thin films may comprise several functional metallic silver-based layers each deposited directly on a zinc oxide-based ground layer, and each ground layer is then preferably bombarded by ions during part or all of its deposition, and preferably only them, and they each exhibit a biaxial texturing: - an out-of-plane texturing with an out-of-plane mosaicity that is less than 15°; and - an in-plane texturing, with an in-plane mosaicity that is less than 50°, preferably less than 26°, or even less than 25°.

[0033] Preferably, said silver-based metallic functional layer(s), deposited directly onto a background layer exhibiting biaxial texturing, shall have biaxial texturing: - an out-of-plane texture with an out-of-plane mosaic pattern of less than 15°; and - an in-plane texture with an in-plane mosaic pattern of less than 50°, preferably less than 26°, or even less than 25°. Thus, the quality, and in particular the crystallinity, of said metallic functional layer(s) thus textured is improved.

[0034] The present invention also relates to the use of an ionic source for the deposition of a stack of thin films on one face of a substrate, glass, according to the invention, said base layer being bombarded by ions during part or all of its deposition, and preferably only it, and exhibits a biaxial texturing: - an out-of-plane texturing with an out-of-plane mosaicity which is less than 15°; and - an in-plane texturing with an in-plane mosaicity which is less than 50°, preferably less than 26°, or even less than 25°.

[0035] The present invention also relates to a glass substrate, coated on one face with a stack of thin films located on one face of a glass substrate, said face having a plane and said stack of thin films comprising a silver-based metallic functional layer deposited directly on a zinc oxide-based ground layer, said stack of thin films being manufactured in particular by the process according to the invention, said ground layer having a biaxial texture: - an out-of-plane texture with an out-of-plane mosaicity which is less than 15°; and - an in-plane texture with an in-plane mosaicity which is less than 50°, preferably less than 26°, or even less than 25°.

[0036] Preferably, said base layer is made of zinc oxide doped with aluminum and / or tin, said doping by a single element or by all elements being preferably between 0.5 and 15.0 atomic percent of the total metallic elements.

[0037] The advantageous details and features of the invention will become apparent from the following non-limiting examples, illustrated with the aid of the accompanying figures: - illustrates an example of a functional single-layer stack ending with a terminal protective layer, the functional layer being deposited directly on a base layer and directly under a blocking overlayer; - illustrates a structure of a functional two-layer stack ending with a terminal protective layer, each functional layer being deposited directly on a base layer and directly under a blocking overlayer; - shows the difference, from left to right, between an untextured silver functional layer, a silver functional layer textured only out of plane and a biaxially textured silver functional layer, with grains oriented out of plane and in plane;-illustrates the texturing in the plane (peak intensity indicated in arbitrary units, as usual), measured by grazing incidence X-ray diffractions (GIXRD), on the left for ZnO according to (100) without beam (center) and with an ion beam (periphery) having an etch / deposition ratio of 20% (400 eV) and on the right, the two resultants, respectively for silver according to (220), without ion beam (center) and with an ion beam (periphery) with an etch / deposition ratio of 20% (400 eV);and illustrates at the top four in-plane textures, measured at grazing incidence (peak intensity shown in arbitrary units), from left to right for silver according to (220), without ion beam, with a 20% (400 eV) ion beam without background layer thickness compensation, with a 20% (400 eV) etch / deposition ratio with background layer thickness compensation to obtain a thickness identical to the first configuration and with a 50% (1000 eV) etch / deposition ratio; and at the bottom four resistance ranges per square without heat treatment, measured for the four top configurations, respectively.

[0038] In leset, the proportions between the thicknesses of the different layers or elements are not strictly respected in order to facilitate their reading.

[0039] The diagram illustrates a single-layer functional stacking structure 14 according to the invention deposited on a face 11 of a transparent glass substrate 10. This diagram illustrates the relative positions of the different layers when these layers are present. The face 11 forms a plane.

[0040] In this structure, the functional layer 140 is silver-based or made of a silver-containing metallic alloy, and is arranged between two antireflective modules: the underlying antireflective module 120 located below the functional layer 140 in the direction of the substrate 10, and the upper antireflective module 160 arranged above the functional layer 140 on the opposite side of the substrate 10.

[0041] These anti-reflective modules 120, 160 each include at least one dielectric layer 125, 128, 129; 162, 165.

[0042] A terminal protective layer 300, furthest from face 11, can complete the stacking.

[0043] For the illustrated single functional layer stacking structure, the functional layer 140 is located directly on the underlying antireflective module 120 which terminates with a background layer 129 as the layer of the first antireflective module furthest from face 11 and is located indirectly under the upper antireflective module 160: there is no subblocking layer located between the underlying antireflective module 120 and the functional layer 140 and there is an overblocking layer 150 located between the functional layer 140 and the upper antireflective module 160.

[0044] The unique metallic functional layer 140 is designed to reflect infrared radiation and / or a portion of solar radiation. The thickness of the metallic functional layer 140 typically ranges from 6 nm to 25 nm, preferably between 10 nm and 20 nm.

[0045] The diagram illustrates a multi-layered functional stacking structure 14 according to the invention deposited on a face 11 of a transparent glass substrate 10. This diagram illustrates the relative positions of the different layers when these layers are present. The face 11 forms a plane.

[0046] In this structure at least one, and preferably each, functional layer 140, 180, is based on silver or a silver-containing metallic alloy, and they are each disposed between two antireflective modules: the underlying antireflective module 120 located below the first functional layer 140 in the direction of the substrate 10 and the intermediate antireflective module 160 disposed above the first functional layer 140 opposite the substrate 10 and below the second functional layer 180. An overlying antireflective module 200 is disposed above the second functional layer 180 opposite the substrate 10.

[0047] These anti-reflective modules 120, 160, 200 each include at least one dielectric layer 125, 128, 129; 162, 165, 168, 169, 202, 205.

[0048] A terminal protective layer 300, furthest from face 11, can complete the stacking.

[0049] For the illustrated two-functional-layer stacking structure, the first functional layer 140 is located directly on the underlying antireflective module 120 which terminates with a background layer 129 as the layer of the first antireflective module furthest from face 11 and is located indirectly under the intermediate antireflective module 160: there is no subblocking layer located between the underlying antireflective module 120 and the first functional layer 140 and there is an overblocking layer 150 located between the first functional layer 140 and the intermediate antireflective module 160.

[0050] For the illustrated two-functional-layer stacking structure, the second functional layer 180 is located directly on the underlying intermediate antireflective module 160 which terminates with a background layer 169 as the layer of the intermediate antireflective module 160 furthest from face 11 and is located indirectly under the antireflective module 200: there is no subblocking layer located between the underlying antireflective module 160 and the second functional layer 180 and there is an overblocking layer 190 located between the second functional layer 180 and the last antireflective module 200.

[0051] Each metallic functional layer 140, 180 is designed to reflect infrared radiation and / or a portion of solar radiation. The thickness of each metallic functional layer 140, 180 can typically be between 6 nm and 25 nm, preferably between 10 nm and 20 nm.

[0052] According to preferred embodiments, each metallic functional layer 140, 180, of a multi-layer functional stack is a silver-based layer.

[0053] The anti-reflective modules of stacks with one or more functional layers may comprise one or more layers of oxides and / or nitrides of metallic elements and / or metallic alloys, such as, for example, zinc oxide, mixed zinc and tin oxide, silicon nitride, silicon oxide, zirconium nitride, titanium oxide, tin oxide, and silicon oxynitride.

[0054] The underlying 120 anti-reflective module may include an absorbent layer. The overlying 200 anti-reflective module may include an absorbent layer.

[0055] The substrate 10 also has another face 9, which may have a stack of thin layers or be without a stack of thin layers.

[0056] Thin-film deposition processes on substrates, particularly glass substrates, are well-known in industry. For example, the deposition of a stack of thin films on a glass substrate is achieved by successively depositing each thin film of the stack by passing the glass substrate through a series of deposition cells adapted to deposit a given thin film.

[0057] Deposition cells can use deposition methods such as magnetic field-assisted sputtering (also called magnetron sputtering), ion beam-assisted deposition (IBAS), evaporation, chemical vapor deposition (CVD), plasma-assisted chemical vapor deposition (PECVD), low-pressure chemical vapor deposition (LPCVD), etc. These methods can be combined: part of a stack (one or more layers) can be produced by one method and one or more other parts (one or more layers) can be produced by one or more other methods.

[0058] Magnetic field-assisted sputtering deposition is a particularly popular process. The deposition conditions for these layers are extensively documented in the literature, for example in patent applications WO2012 / 093238 A1 and WO2017 / 00602 A1.

[0059] In these stacks with one or more functional metallic layers, a balance must be struck between maximizing reflection in the far-infrared range to minimize heat loss to the outside, maintaining transparency in the visible spectrum for interior comfort, and harnessing solar energy for passive interior heating. Achieving this balance typically involves thin-film stacks with one or more silver-based or silver-clad layers, approximately 10 nm thick (ranging from about 6 to 18 nm), serving as the active element for infrared reflection. According to the Hagens-Rubens relationship, a metal's infrared reflectivity is closely linked to its conductivity, making silver an ideal choice due to its low resistivity. Since the nanometer-scale thickness is the result of an infrared / visible trade-off, minimizing the film's resistivity is crucial for controlling the stack's performance.

[0060] The three parts schematically illustrate three different states of a continuous silver metallic layer which is polycrystalline and whose set of crystalline planes is represented by parallel lines at the level of each single crystal (grain), with for each part, at the bottom the visualization of the orientation of the grains in the most favorable XY plane (for example the plane of a main face of a substrate) and at the top, the orientation of the grains outside this plane, along the Z axis.

[0061] The left side illustrates the state of a continuous metallic silver layer deposited on an amorphous (non-crystallised) background layer.

[0062] To improve the crystalline properties of Ag, and thus reduce its resistivity, a polycrystalline zinc oxide ground layer is regularly used beneath the Ag layer. Indeed, it is known that ZnO plays a beneficial role in improving the texture of a silver-based layer deposited on top. The central part of the image illustrates this: silver grains are roughly aligned with each other along the Z direction, and some atomic planes (mainly oriented along (111)) are aligned in the same direction, but this texturing of Ag by ZnO only occurs in the out-of-plane orientation. In the plane, all the grains are misoriented, creating a polycrystalline structure without a preferred orientation.

[0063] The right-hand side of the illustration shows the generation of a biaxial texture, that is to say both out of plane and in plane, thanks to the invention, thus causing an improvement in the crystallinity of the Ag layers.

[0064] To achieve this, it is proposed to use ion beam assisted sputtering (IBAS) technology.

[0065] The principle of this technology consists of simultaneously performing a reactive sputtering deposition of a Zn-based target or a non-reactive target using a ZnO-based target (or a weakly reactive target using a ZnO-based target), and at the same time bombarding the growing ZnO layer with an ion beam.

[0066] For the initial tests, an ion beam gun (Tectra Gen II model) was mounted on a flange in a sputtering coating deposition system, at a 45° angle to the substrate. The distance between the gun and the sample plane was 217 mm, while the distance between the target and the substrate was 149 mm. The bombardment energy ranged from a few eV to 2 keV. The etching rate of the gun was previously calibrated by measuring ion currents collected by a Ta plate or on Si wafers.

[0067] ZnO deposition is performed reactively with a pure Zn metallic target (DC mode, P=50W applied to the target, deposition rate: 0.4 nm / s) with an Ar / O2 gas ratio of 7.5. The chamber base pressure is a maximum of 10 -7 mbar, and the working pressure is 3.4 x 10 -3 mbar.

[0068] The first phase of the study focused on the growth of ZnO films on glass substrates (4 cm x 4 cm) encapsulated by layers of silicon nitride (Si3N4:Al). Different ZnO growth rates (3 minutes deposition time, approximately 70 nm) were obtained for different gun bombardment energies. The effect of the bombardment can be quantified by calculating the ratio between the ablation velocity of the gun and the ZnO deposition rate. When an energy of 1 keV is generated, the resulting ratio is 50%, corresponding to a thickness half that of the film not bombarded by the gun (35 nm instead of 70 nm).

[0069] The two dielectric layers (Si3N4:Al) for the lower and upper layers were deposited in a separate deposition frame under the following conditions: 2000 W, 2 μbar, Ar flow rate 18 sccm, N2 flow rate 20 sccm, working pressure 2.10 -3mbar, frequency: 50 kHz.

[0070] All these ZnO films were structurally characterized by X-ray diffraction (XRD) measurements, initially focusing on out-of-plane configurations via θ / 2θ measurements. Furthermore, the gun bombardment effect, simultaneous with growth, promotes out-of-plane texturing of the ZnO films and increases the size of Scherrer crystallites along the growth axis perpendicular to the surface, to a value greater than 3.9 nm (value obtained without IBAS).

[0071] This improvement in the crystalline properties of ZnO films, thanks to the invention, is also manifested by a reduction in the mosaicity of out-of-plane films to a value below 15° (a value above 15° was obtained without IBAS). Furthermore, the grain misorientation tends to decrease inversely with the bombardment energy and the ionic flux used, reaching an average misorientation of around 8° for a bombardment energy of 1 keV.

[0072] This increase in out-of-plane texturing is also accompanied by in-plane texturing as the bombardment energy increases. Grazing incidence X-ray diffraction (GIXRD) measurements revealed a 6-symmetry diffraction anisotropy, corresponding to the wurtzite structure of ZnO for films deposited by IBAS. This anisotropy manifests as an improvement in the texture coefficient, or Lotgering factor, of the ZnO(100) peak, ranging from 16.3% without IBAS to 64.8% for a 1 keV bombardment.

[0073] Table 1 below summarizes the data observed for ZnO.

[0074] Without IBASIBAS (10%)IBAS (20%)IBAS (40%)IBAS (50%)Scherrer vertical grain size (nm)3,94,66,07,47.8Out-of-plane mosaicity (°)>1513,59,59,38.1In-plane mosaicity (°)>10025,125,723,021.5RMS roughness (nm)0.891,551.81--Texture coefficient for ZnO (100) (%)16,334,235,458,564.8

[0075] However, the atomic force microscopy (AFM) study indicates an increase in the surface roughness of the ZnO films when using the ion gun, a result contrary to what is observed in the literature where the effect of IBAS deposition presents the opposite effect of reducing the roughness of the films.

[0076] The second phase of the study focused on stacks with a single 12 nm Ag layer deposited on textured ZnO, with both layers encapsulated in silicon nitride (Si3N4:Al) films. Ion beam-assisted deposition is performed solely on the ZnO film, and the Ag is deposited without the use of an ion-beam gun.

[0077] The diffraction spectra of the ZnO / Ag stacks without and with the use of the ion beam gun were compared: an increase in the combined diffraction peaks of ZnO(002) and Ag(111) using ion bombardment is observed, indicating improved out-of-plane texturing of ZnO and Ag.

[0078] Lamontre observed that by performing grazing incidence measurements (GIXRD) on these two films targeting the peaks of ZnO(100) and Ag(220), the in-plane texturing generated in the ZnO film using ion bombardment induces in-plane texturing of the Ag deposited on top, with a pronounced anisotropy. This epitaxy occurs in a hexagon / hexagon stacking pattern without rotation in real space (60° rotation in reciprocal space) and without lattice shift effects of -11.5%.

[0079] These GIXRD measurements are confirmed by low-energy electronic diffraction (LEED) measurements. On a relatively thick Ag film (25 nm) deposited on a textured ZnO film: the diffraction patterns (obtained at the surface of the silver layer with a device present in the deposition frame) confirmed the epitaxy of Ag on the ZnO, and therefore the in-plane texturing of the Ag.

[0080] Next, the evolution of the electrical resistance of biaxially and non-biaxially textured Ag films was studied. Four samples were prepared, each with an Ag layer 12 nm thick and a ZnO layer thicker. In the first sample, the ZnO film was not subjected to ion bombardment and was 70 nm thick. In the second sample, the ZnO layer grew under an ion bombardment energy of 0.4 keV (20% ratio), resulting in a final thickness of 55 nm. The third sample was identical to the previous one, except that the ZnO thickness was compensated to obtain exactly 70 nm. Finally, the last sample used an energy of 1 keV (50% etching / deposition ratio), resulting in a ZnO layer thickness of 35 nm.

[0081] The upper part of the illustration shows the in-plane texturing, measured by grazing incidence X-ray diffractions (GIXRD), for the silver layer of the four samples, in this order, from left to right, and the lower part of the illustration shows the resistance per square, Rs, of the four samples, in the same order and without any heat treatment.

[0082] Each time, - an improvement in in-plane texture was observed, that is, an increase in the in-plane crystalline quality of a silver layer deposited on a ZnO layer deposited with the IBAS process compared to the same silver layer deposited on the same ZnO layer deposited under standard conditions without simultaneous ion bombardment (without IBAS); - an improvement in out-of-plane texture was observed, that is, an increase in the out-of-plane crystalline quality of a silver layer deposited on a ZnO layer deposited with the IBAS process compared to the same silver layer deposited on the same ZnO layer deposited under standard conditions without simultaneous ion bombardment (without IBAS); and - a reduction in strength per square of between 10% and 12% was observed for the three samples treated by IBAS.

[0083] To complete the study, a short anneal at 650°C for 2 min was carried out on each sample and a gain (a decrease in resistance per square) of between 10% and 13% was observed for the three samples treated by IBAS compared to the untreated sample.

[0084] Thinner ZnO thicknesses were also tested: with thicknesses of 5 nm, a gain of 12% is still obtained between the samples treated by IBAS and those not treated, whether before or after annealing at 650°C for 2 min.

[0085] The optical properties of textured films using an Ar ion beam gun were also investigated. Table 2 below summarizes the observed data for resistance per square and defined energy absorption, measured and calculated in accordance with EN 410.

[0086] Without IBAS With IBAS (20%) (400 eV) ZnO thickness (nm) 570 570 Resistance per square without heat treatment (Ω / Δ) 3.9 33.9 33.4 33.55 Resistance per square after annealing (Ω / Δ) 3.4 8 3.6 3.0 2 3.26 Visible absorption without heat treatment (%) 8.9-7.9- Visible absorption after annealing (%) 8.2-7.0-

[0087] It has been observed that the visible light absorption rate is reduced by approximately 1% for textured films compared to a film that has not been bombarded with the Ar flux. This 1% absorption reduction is also observed when the films are annealed at 650°C for 2 minutes, regardless of the thickness of the ZnO base layers.

[0088] It has also been observed that these ion beam assisted deposition effects can be optimized by varying the treatment sequence during the deposition of the ground layer. Furthermore, a ZnO deposition in which the ion treatment is stopped after 1 / 9 of the deposition time leads to the observation that the crystallinity of the Ag film improves for a given thickness (normalized thickness). Indeed, the size of the out-of-plane crystallites ranges from 7.8 nm for simultaneous etching (full IBAS) to 16.2 nm for a deposition where the etching is stopped after 1 / 9 of the deposition time.

[0089] Furthermore, ion treatment was tested during the deposition of an AZO film: the deposition is performed reactively with a 2% Al-doped Zn target. Two samples were compared, both exhibiting the same structure: a 70 nm thick AZO layer encapsulated by silicon nitride (Si3N4:Al) layers. One AZO layer was deposited without the IBAS process, and the other with it. Theta / 2theta measurements showed an improvement in the size of the out-of-plane crystallites, increasing from 5.9 nm to 6.9 nm with the IBAS-deposited film. Thanks to grazing incidence measurements (GIXRD), a texturing effect in the plane is also observed for the layer deposited by IBAS, with in addition a Lotgering texture coefficient on the ZnO(100) increasing from 26% without IBAS to 71% with IBAS.

[0090] In the examples, the functional metallic layers 140 and 180 are silver (Ag) layers. The overblocking layers 150 and 190 are nickel-chromium alloy (NiCr) metallic layers. The antireflective modules 120, 160, and 200 comprise barrier layers, smoothing layers, and base layers. The barrier layers 125, 165, and 205 are silicon nitride-based, such as aluminum-doped silicon nitride (Si3N4:Al) or zirconium-silicon nitride. The smoothing layers 128 and 168 are zinc-tin oxide (SnZnOx). The base layers 129 and 169 are zinc oxide (ZnO) or aluminum-doped zinc oxide (AZO).

[0091] Name Content Stoichiometry Index (at 550 nm) Si3N4:Al Aluminum-doped silicon nitride Si3N4:Al2.05SiZrN27 Zirconium-silicon nitride Si x’ Zr y’ N z’with y / (y + x) = 0.272.40 ZnO₂ zinc oxide ZnO₂ 1.90 A₂O₂ aluminum-doped zinc oxide ZnO:Al 1.90 Sn ZnO₂ zinc-tin oxide Sn e Zn f O2.00NiCrNickel-Chromium AlloyNi 0,8 Cr 0,2 -AgAg-

[0092] The conditions for the deposition of the layers, which were deposited by sputtering (so-called "magnetron cathode sputtering"), are summarized in Table 4.

[0093] Target layer used Deposition pressure Gas Si3N4Si:Al at 92:8 wt% 3.2-6.10 -3 mbarAr / (Ar + N2) at 55%SiZrN27Si:Zr:Al at 68:27:5% at.2.10 -3 mbarAr / (Ar + N2) at 45%ZnOZn2.10 -3 mbarAr / (Ar + O2) at 25% AZOZn:Al at 98:2% by weight 1.8 x 10 -3 mbarAr / (Ar + O2) at 65%SnZnOZn:Sn at 64:36% at.2.10 -3 mbarAr / (Ar + O2) at 50% NiCrNi:Cr at 80:20% at.2-3.10 -3 mbarAr at 100% AgAg8.10 -3 mbarAr at 100%

[0094] at. = atomic

[0095] It has been observed that the quality, and in particular the crystallinity, of said textured metallic functional layer(s) deposited directly on a background layer with biaxial texturing is improved.

[0096] The present invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different variations of the invention without departing from the scope of the patent as defined by the claims.

Claims

Method for depositing a stack of thin films (14) on a face (11) of a glass substrate (10) by sputtering, said face (11) having a plane and said stack of thin films (14) comprising a metallic functional layer (140, 180) based on silver deposited directly on a ground layer (129, 169) based on zinc oxide, said method comprising the use of an ion source, characterized in that said ground layer (129, 169) is bombarded by ions during part or all of its deposition, and preferably only it, and exhibits a biaxial texturing: - an out-of-plane texturing with an out-of-plane mosaicity which is less than 15°; and - an in-plane texturing with an in-plane mosaicity which is less than 50°, preferably less than 26°, or even less than 25°. A method according to claim 1, wherein said ion bombardment is a bombardment of argon, xenon, helium, neon or krypton ions, or even dioxygen. A method according to claim 1 or 2, wherein said ground layer (129, 169) is bombarded for 1 / 15 e at 3 / 4 of the deposition time of said background layer (129, 169). A method according to any one of claims 1 to 3, wherein said bombardment is carried out with an energy between 100 and 2,000 eV, in particular between 400 and 2,000 eV. A method according to any one of claims 1 to 4, wherein said base layer (129, 169) is deposited by reactive spraying using a zinc metallic target or a ZnO ceramic target, said target preferably being doped with aluminum and / or tin, said doping with a single element or with all elements preferably being between 0.5 and 15.0 atomic % of the total metallic elements. A method according to any one of claims 1 to 5, wherein said ion bombardment is carried out at an angle of 45° plus or minus 30°, preferably plus or minus 15°, with respect to said face (11) of the substrate (10). A method according to any one of claims 1 to 6, wherein said stack of thin films (14) comprises several metallic functional layers (140, 180) based on silver, each deposited directly on a ground layer (129, 169) based on zinc oxide, and wherein each ground layer (129, 169) is bombarded by ions during part or all of its deposition, and preferably only them, and each exhibits a biaxial texturing: - an out-of-plane texturing with an out-of-plane mosaicity that is less than 15°; and - an in-plane texturing with an in-plane mosaicity that is less than 50°, preferably less than 26°, or even less than 25°. A method according to any one of claims 1 to 7, wherein said or said metallic functional layer(s) (140, 180) based on silver, itself deposited directly on a ground layer (129, 169) having a biaxial texture, exhibits a biaxial texture: - an out-of-plane texture with an out-of-plane mosaicity that is less than 15°; and - an in-plane texture with an in-plane mosaicity that is less than 50°, preferably less than 26°, or even less than 25°. Use of an ionic source for the deposition of a stack of thin films (14) on a face (11) of a glass substrate (10), according to any one of claims 1 to 8, characterized in that said background layer (129, 169) is bombarded by ions during part or all of its deposition, and preferably only it, and exhibits a biaxial texturing: - an out-of-plane texturing with an out-of-plane mosaicity which is less than 15°; and - an in-plane texturing with an in-plane mosaicity which is less than 50°, preferably less than 26°, or even less than 25°. Glass substrate (10), coated on one face (11) with a stack of thin films (14) located on one face of a glass substrate (10), said face (11) having a plane and said stack of thin films (14) comprising a metallic functional layer (140, 180) based on silver deposited directly on a ground layer (129, 169) based on zinc oxide, said stack of thin films (14) being in particular manufactured by the process according to any one of claims 1 to 8, characterized in that said ground layer (129, 169) has a biaxial texture: - an out-of-plane texture with an out-of-plane mosaicity which is less than 15°; and - an in-plane texture with an in-plane mosaicity which is less than 50°, preferably less than 26°, or even less than 25°. Substrate (10) according to claim 10, wherein said base layer (129, 169) is made of zinc oxide doped with aluminum and / or tin, said doping by a single element or by all elements being preferably between 0.5 and 15.0 atomic % of the total metallic elements.

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