WO2014006322A1

WO2014006322A1 - Insulating glass panel

Info

Publication number: WO2014006322A1
Application number: PCT/FR2013/051555
Authority: WO
Inventors: Augustin PALACIOS-LALOY; Bertrand Kuhn
Original assignee: Saint-Gobain Glass France
Priority date: 2012-07-06
Filing date: 2013-07-02
Publication date: 2014-01-09
Also published as: CN104395257A; IN2014DN10830A; CN104395257B

Abstract

The invention relates to transparent glass panel, consisting of at least one glass sheet provided, on at least one of the surfaces thereof, with a coating consisting of a stack of thin films of which at least one functional film imparts solar control properties to said glass panel, said glass panel including, from the surface of the substrate: at least one underlayer of a dielectric material; at least one functional niobium layer having a physical thickness of 5 nm to 35 nm; at least one overlayer made of a dielectric material for protecting said functional layer(s) from the external environment, said glass panel being characterised in that at least one of said functional layers also includes oxygen, the ratio of NbO/Nb signals in said layer, according to SIMS analysis, being between 1.8 and 2.8.

Description

INSULATING GLAZING

The invention relates to so-called solar control insulating glazings, provided with stacks of thin layers, at least one of which is functional, that is to say that it acts on solar radiation and / or heat essentially by reflection. and / or absorption of near-infrared (solar) or far-infrared (thermal) radiation. The present invention relates more particularly to glazing with layer (s) in particular those intended primarily for the thermal insulation of buildings.

For the purposes of the present application, the term "functional" or "active" layer is understood to mean the layer (or layers) of the stack which confers on the stack the bulk of its thermal properties. Most often the thin-film stacks equipping the glazing give it substantially improved properties of solar control essentially by the intrinsic properties of this active layer. Said layer acts on the flow of solar radiation passing through said glazing, as opposed to the other layers, generally made of dielectric material and having the function of a chemical or mechanical protection of said functional layer.

Such glazings provided with stacks of thin layers act on the incident solar radiation either essentially by the absorption of the incident radiation by the functional layer, or essentially by reflection by this same layer.

They are grouped under the designation of solar control glazing. They are marketed and used mainly:

or to essentially protect the dwelling from solar radiation and prevent overheating thereof, such glazings being qualified in the antisolar trade,

- Or mainly to ensure thermal insulation of the home and prevent heat loss, these windows being called insulating glass.

For the purposes of the present invention, sunscreen means the faculty of glazing to limit the energy flow, in particular the radiation Solar infrared (1RS) crossing from the outside to the interior of the house or the cabin.

By thermal insulation is meant a glazing unit provided with at least one functional layer giving it a reduced energy loss, said layer having IR reflection properties of between 5 and 50 microns.

In some countries, the standards imply that glazing has both solar control and thermal insulation properties, even for single glazing, that is, incorporating only one sheet of glass.

In a well-known manner, for example described in the reference publication "Engineering techniques, Glass with reinforced thermal insulation, C3635 (2004)", the reflection property of the IR is proportional to the resistance per square R _D measured on the stack in which is included said functional layer, also called surface resistance.

Good thermal insulation properties thus require in the first place a low resistivity of the functional layer. Such a property however also results in a greater light absorption, which tends to significantly reduce the light transmission within the glazing. The object of the present invention is to provide a window with a stack having a good compromise between its light transmission and its thermal insulation properties, as measured by the square resistance of the stack.

In general, all the luminous characteristics presented in the present description, in particular the light transmission T _L , are obtained according to the principles and methods described in the international standards ISO 9050 (2003) relating to the determination of the luminous characteristics. glazing used in glass for construction.

Ideally, these windows provided with functional stacks must be capable of undergoing heat treatment of the quenching, annealing or bending type, without significant variation, or at least without degradation, in their initial optical and / or energetic properties. In particular, after the heat treatment, the glazings provided with layers according to the invention must maintain an acceptable light transmission and have a preferably improved, or at least substantially unchanged, square strength.

The best performing stacks marketed at present incorporate at least one silver-like metal layer operating essentially in the reflection mode of a major part of the incident IR (infrared) radiation. These stacks are thus used mainly as glazing type low emissive (or low-e in English) for the thermal insulation of buildings. These layers, however, are very sensitive to moisture and are therefore exclusively used in double glazing, on the face 2 or 3 of it, to be protected from moisture. It is thus not possible to deposit such layers on single glazing (also called monolithic). The stacks according to the invention do not include such layers of the Silver type, or of the Gold or Platinum type or else in very negligible quantities, especially in the form of unavoidable impurities.

Other metal layers with an antisolar function have also been reported in the field, comprising functional layers of the Nb type metal or nitride, as described for example in the application WO01 / 21540 or in the application WO2009 / 1 12759. Within of such layers, the solar radiation is this time mainly absorbed non-selectively by the functional layer comprising niobium, the IR radiation (that is to say whose wavelength is between about 780 nm and 2500 nm ) and the visible radiation (whose wavelength is between about 380 and 780 nm) being absorbed without distinction by the active layer.

These coatings are conventionally deposited by magnetic field-assisted vacuum sputtering techniques of a cathode of the material or a precursor of the material to be deposited, often referred to as the magnetron sputtering technique in the field. Such a technique is today conventionally used in particular when the coating to be deposited consists of a more complex stack of successive layers of thicknesses of a few nanometers or a few tens of nanometers. As indicated above, another constraint is also necessary when developing a glazing: especially when it consists of a single glass substrate, it must most often undergo one or more heat treatments which may be a bending if we want to give them a curve (showcase) but which is mostly a temper, especially in the building sector, where we want it to be more resistant and less dangerous in case of shocks. The fact that layers are deposited on the glass before its heat treatment can lead to their deterioration and a significant change in their properties, including optical. On the other hand, depositing the layers after the heat treatment of the glass proves to be complex and expensive. As described above, it is therefore imperative that such glazings provided with such layers can undergo such heat treatments without significant variation in their initial properties, thermal as optical.

The object of the present invention is to provide a glazing having both reinforced thermal insulation properties and a strong light transmission, for example a light transmission factor T _{L of} greater than 45%, preferably close to less 50% or even more than 50%, and which has no or almost no change in its solar control properties after a heat treatment, including quench type.

The object of the invention thus consists first and foremost of a transparent glazing consisting of at least one glass sheet provided on at least one of its faces with a coating constituted by a stack of thin layers, of which at least one layer functional unit conferring on said glazing solar control properties, said glazing comprising, from the surface of the substrate: at least one underlayer of a dielectric material,

at least one niobium functional layer, of physical thickness greater than 5 nm and less than 35 nm,

at least one protective layer of the at least one functional layer vis-à-vis the external environment, made of a dielectric material, said glazing being characterized in that said functional layer further comprises oxygen, the ratio of NbO / Nb signals in said layer, in SIMS analysis, being between 1, 8 and 2.8.

According to the invention, the measurement corresponds to the ratio of the integrated areas of the NbO and Nb signals on the portion of the SIMS profiles for which the signal intensity Nb is significant (non-zero).

Preferably, all the functional layers in the stack are made of niobium.

By functional layer in (or of) niobium is meant that the functional layer (s) consist (apart from oxygen) of niobium, and possibly unavoidable impurities.

The functional layer according to the invention thus consists solely of niobium, oxygen and possibly unavoidable impurities, such as those resulting especially from a magnetron sputtering deposition process.

According to one possible embodiment, the stack comprises only a functional niobium layer.

Preferred embodiments of the present invention are described in the appended claims.

In particular :

The ratio of the NbO / Nb signals in said layer is between 2.0 and 2.8, and very preferably between 2.1 and 2.5.

The functional layer has a thickness of between 5 and 20 nm.

The stack comprises a single functional layer made of niobium.

Said stack comprises two layers of a material selected from the group consisting of Ti, Mo, Al or an alloy comprising at least one of these elements, preferably Ti, disposed above and below each functional layer and in contact therewith, said layer having a physical thickness of between about 0.2 nm and about 2 nm.

The stack comprises a single sub-layer consisting essentially of a nitride or an oxynitride of aluminum and / or silicon, with a physical thickness of between 30 and 60 nm, preferably of a layer constituted by essentially silicon nitride, optionally further comprising aluminum.

- The stack comprises a single layer consisting essentially of a nitride or an oxynitride of aluminum and / or silicon, with a physical thickness of between 30 and 60 nm, preferably a layer consisting essentially of nitride silicon, optionally further comprising aluminum.

The stack comprises, above the functional layer, a succession of a layer essentially of a nitride or an oxynitride of aluminum and / or of silicon and of a layer of an oxide chosen from oxide; of silicon and titanium oxide, the total optical thickness of said overlayer being between 80 and 1 10 nm. The succession consists in particular of a layer consisting essentially of silicon nitride and a layer of silicon oxide, the physical thickness of the silicon nitride layer being between 40 and 50 nm and the physical thickness of the silicon oxide layer being between 3 and 10 nm.

- The overlay is constituted by the succession of a layer consisting essentially of silicon nitride and a titanium oxide layer, the physical thickness of the silicon nitride layer being between 30 and 45 nm and the physical thickness of the titanium oxide layer being between 5 and 15 nm.

The total optical thickness of said overlayer is between 90 and 105 nm, in particular between 90 and 100 nm.

- The glazing is thermally tempered and / or curved.

According to a particular embodiment of the glazing according to the invention, said coating is constituted by a stack of thin layers, at least two niobium functional layers further comprising oxygen so that the ratio of signals NbO / Nb in said layers, in SIMS analysis, between 1, 8 and 2.8.

Such a coating comprises in particular at least, from the surface of the substrate:

at least one underlayer of a dielectric material, a first functional layer made of niobium, in particular of physical thickness greater than 10 nm and less than 25 nm,

at least one intermediate layer made of a dielectric material,

a second functional layer made of niobium, in particular of physical thickness greater than 5 nm and less than 20 nm,

at least one overlayer of a dielectric material.

According to preferred embodiments of this particular mode comprising two functional layers, which can be optionally combined with one another:

the ratio of the NbO / Nb signals in said layers is between 2.0 and 2.8 and very preferably between 2.1 and 2.5,

the first functional layer has a thickness of between 12 and 25 nm and in which the second functional layer has a thickness of at least 5 nanometers less than the first, in particular between 6 and 20 nm,

said coating further comprises at least one layer of physical thickness between about 1 nm and about 3 nm of a material selected from the group consisting of Ti, Mo, Al or an alloy comprising at least one of these elements preferably Ti, arranged with respect to the glass substrate above and below the two functional layers and in contact therewith,

said glazing comprises a single sub-layer consisting essentially of a nitride or an oxynitride of aluminum and / or silicon, with a physical thickness of between 30 and 60 nm, preferably of a layer consisting essentially of nitride silicon, optionally further comprising aluminum,

said glazing comprises a single overlayer consisting essentially of a nitride or an oxynitride of aluminum and / or silicon, with a physical thickness of between 30 and 60 nm, preferably of a layer consisting essentially of nitride silicon, optionally further comprising aluminum,

said glazing comprises, above the functional layer, a succession a layer essentially of a nitride or an oxynitride of aluminum and / or silicon and a layer of an oxide chosen from silicon oxide and titanium oxide, the total optical thickness said overlayer being between 80 and 1 10 nm, said succession consisting for example of a layer consisting essentially of silicon nitride and a silicon oxide layer, the physical thickness of the silicon nitride layer being between 40 and 50 nm and the physical thickness of the silicon oxide layer being between 3 and 10 nm,

the overlayer is formed by the succession of a layer consisting essentially of silicon nitride and a titanium oxide layer, the physical thickness of the silicon nitride layer being between 30 and 45 nm and the physical thickness of the titanium oxide layer being between 5 and 15 nm,

the total optical thickness of said overlayer is between 90 and 105 nm, in particular between 90 and 100 nm,

the intermediate layer between two functional layers is a layer consisting essentially of a nitride or an oxynitride of aluminum and / or silicon, with a physical thickness of between 30 and 60 nm, preferably of a layer consisting essentially of silicon nitride, optionally further comprising aluminum,

the intermediate layer between two functional layers is a layer consisting of an oxide, in particular a mixed oxide of zinc and tin, preferably with a physical thickness of between 30 and 60 nm,

the stack of thin layers is arranged on the face 2 of a single glazing unit (a single sheet of glass) by numbering the faces of the substrate from the outside to the inside of the building or cabin that it equips,

the glazing is thermally tempered and / or curved.

The invention also relates to a facade facing facade type panel incorporating at least one glazing as previously described.

The present invention also relates to the stack of layers as described above, this stack comprising at least one sub-layer. layer of a dielectric material, at least one niobium functional layer, with a physical thickness greater than 5 nm and less than 35 nm, at least one protective overcoat of the functional layer or layers with respect to the external environment , in a dielectric material. In the sense previously described, in the stack according to the invention, said niobium functional layer further comprises oxygen in a proportion such that the ratio of NbO / Nb signals in said layer, in SIMS analysis, is between 1 , 8 and 2.8, preferably between 2.0 and 2.8 and most preferably between 2.1 and 2.5.

The invention finally relates to a method of manufacturing a glazing unit as previously described, comprising at least the following steps:

a glass substrate is introduced into a sputtering device,

in an earlier compartment, an underlayer of a dielectric material is deposited,

in a subsequent compartment, a metal niobium target is sprayed with a plasma generated from a mixture consisting of a neutral gas such as argon and oxygen, the volume proportion of O 2 in the gaseous mixture being between 2 and 5% by volume of O 2,

in a posterior compartment, an overlay of a dielectric material is deposited.

In such a manufacturing method, it is further possible to provide deposition steps, in intermediate compartments of the device, of metallic titanium between the dielectric material layers and the niobium functional layers.

The present invention also relates to a facade cladding facade type panel incorporating at least one glazing as described above or a side window, a rear window or a roof for automobile or other vehicle constituted by or incorporating said glazing.

According to the invention, the functional layers according to the invention make it possible to obtain a value of the light transmission of the substrate relatively high, while maintaining a significant insulating effect, despite the very low thickness of the functional layer, after a heat treatment.

By the terms "under layer" and "on-layer", reference is made in the present description to the respective position of said layers relative to the functional layer or layers in the stack, said stack being supported by the glass substrate.

In particular, the sub-layer is generally the layer in contact with the glass substrate and the overlayer is the outermost layer of the stack, turned away from the substrate,

Without departing from the scope of the invention, it is possible according to the invention to substitute the silicon of the preceding layers consisting essentially of silicon nitride, by elements of the Al, Zr, B, etc. type, so as to modify the color transmission and / or reflection of the glazing, according to techniques well known in the art and in proportions of up to 10 atomic%.

If the application more particularly targeted by the invention is glazing for the building, it is clear that other applications are possible, especially in the windows of vehicles (apart from the windshield where a very demanding high light transmission), such as side glasses, roof-car, rear window.

The invention and its advantages are described in more detail, below, by means of the nonlimiting examples below, according to the invention and comparative. In all the examples and the description, the given thicknesses are physical.

All the substrates are 6 mm thick clear glass of Planilux type marketed by Saint-Gobain Glass France.

All layers are deposited in a known manner by magnetic field assisted sputtering (often called magnetron).

In a well-known manner, the different successive layers are deposited in the successive compartments of the spraying device cathode, each compartment being provided with a specific metal target Si, Ti or Nb, chosen for the deposition of a specific layer of the stack.

More specifically, the silicon nitride layers are deposited in a first compartment of the device from a metal silicon target (doped with 8% by weight of aluminum), in a reactive atmosphere containing nitrogen (40% Ar and 60% N ₂ ). The Si3N layers therefore contain a little aluminum. These layers are subsequently designated according to the general formulation Si ₃ N ₄ , even if the deposited layer does not necessarily respond to this supposed stoichiometry.

The metallic Ti layers are obtained by sputtering a metal titanium target.

The metallic Niobium layers are deposited from the sputtering of Nb targets in an inert atmosphere (i.e. using a plasma obtained from Argon gas alone) or in a plasma generated essentially from Argon gas but comprising a minimum and variable amount of oxygen according to different embodiments, in the proportions given in Table 1 below.

In all the examples which follow, the glass substrate has thus been successively covered with a stack of layers comprising a functional layer made of Nb, titanium blockers arranged on either side of said functional layer, and undercoats and overcoated layers. Si3N.

The deposition conditions were adjusted according to conventional techniques to obtain a stack corresponding to the following sequence:

Glass / Si ₃ N ₄ (46 nm) / Ti (1 nm) / Nb (6 nm) / Ti (1 nm) / Si ₃ N ₄ (46 nm)

The total gas pressure is set at 2.5 mTorr in all deposition compartments, with the exception of the compartments in which the two layers of Ti blockers are deposited where the total pressure is set at 3.5 mTorr.

The samples of the following examples were obtained by varying the amount of oxygen gas introduced into the plasma between 0 and 5.7% by volume. A- Measurement of glazing characteristics before and after heat treatment Square resistance is measured by a SRM12 device (Sheet

Resistivity Meter) marketed by the company Nagy. The device produces a primary magnetic field which in response generates a secondary magnetic field in the sample. This secondary field is measured by the device, the comparison of the primary and secondary magnetic fields allowing the "non-contact" determination of the corresponding value of R / square.

The values of light transmission T _L (according to the illuminant D ₆ s) and of R _D are measured for the glazing provided with the stack first at the output of the magnetron line and then after a heat treatment consisting of heating at 620.degree. ° C for 10 minutes followed by quenching.

The results obtained are summarized in Table 1 which follows:

Optical properties

O2 and energy rates

Treatment

EXAMPLE in plasma

thermal

(% volume) T _L R _n

Before 51, 3 76

Example 1 0

After 45.9 174

Before 51, 1 80

Example 2 0.6

After 46.0 185

Before 51, 0 87

Example 3 1, 5

After 47.2

Before 50.9 92

Example 4 1, 8

After 47.3 160

Before 51, 2 95

Example 5 2.2

After 47.6 160

Before 51, 2,105

Example 6 2.6

After 48.9 135

Before 50.9 1 10

Example 7 2.9

After 49.0 130

Before 51, 0 125

Example 8 3.3

After 49.5 140

Before 50.6 130

Example 9 3.6

After 49.7 130

Before 48.8 200

Example 10 4.3

After 48.7 170

Before 49.0 215

Example 1 1 5.7

After 49.0 185

Table 1 The data reported in Table 1 show that the glazing according to Example 1 according to the prior art initially has very good initial properties and a very good compromise between the light transmission T _L and the resistance by square. However, it is clear from the data reported in Table 1 that its very good initial properties are greatly degraded when the glazing is subjected to heat treatment.

The addition of a small amount of oxygen in the argon plasma used for deposition of the niobium layer, in particular of a proportion of between 2 and 4% of the total gaseous volume, makes it possible to obtain stability or even an improvement in the characteristics of the glazing before and after the heat treatment. The insulating glass units obtained according to Examples 8 or 9 thus have a remarkable stability of the optical and conductivity characteristics before and after the heat treatment.

On the contrary, the addition in the argon plasma of an excessively large amount of oxygen, in particular greater than 5%, results on the contrary in a very significant degradation of the resistance per square of the stack and therefore of the properties insulating glazing.

B- Measurement of the oxygen content present in the functional layer

The functional layers of the previous stacks were analyzed using the SIMS technique (Secondary Ionization Mass Spectrometry).

Secondary ion mass spectrometry is a process that involves bombarding the surface of the stack to be analyzed with an ion beam. The sample is pulverized, and some of the pulverized material is ionized. The so-called secondary ions are accelerated to a mass spectrometer that will measure the elemental, isotopic or molecular composition of the surface of the sample.

More precisely, the experimental conditions of the measurement carried out are defined below: The depth profiles of the stacks according to examples 1, 6, 9 and 10 above were obtained using TOF SIMS 5 equipment from IONTF. The profile of the secondary ions is obtained by using as a source of primary ions the Bi ₃ ²⁺ ions at 60 keV with a pulsed current of 0.3 pA (with a 7 ns tap and a cycle time of 100 microseconds) and as abrasive species of Cs ⁺ ions at 1 keV, with a pulsed current of 50 nA. The sprayed surface is a square of 200 micrometers apart. The analyzed region is a square of 50 microns side centered on the bottom of the crater. An electron gun is used to neutralize the surface in order to reduce charging effects.

The results of the SIMS analysis obtained for Examples 1, 6, 9 and 10 above are reported in Table 2 below. Measuring the ratio of NbO / Nb signals allows accurate quantification of the amount of oxygen present in the layer. According to the invention and as reported in Table 1, the measurement corresponds to the ratio of the integrated areas of the NbO and Nb signals on the portion of the SIMS profiles for which the signal intensity Nb is significant (non-zero). The oxygen concentration obtained for the sample according to Example 1, in which the functional layer has been deposited in a plasma exclusively of neutral gas, is very low, or even zero. In contrast, the analysis of the NbO / Nb signal ratio in the case of Examples 6, 9 and 10 shows that a significant amount of bound oxygen is present in the metallic niobium network constituting the functional layer.

FIG. 1 shows, by way of information, the NbO and Nb signals obtained for the sample according to Example 9.

In order to determine the corresponding oxygen percentages in the niobium layers of the samples according to Examples 6, 9 and 10, the depth profiles of the stacks were also measured by the XPS method (photoelectron spectrometry X, or photoelectron spectrometry induced by X-rays or X-Ray photoelectron spectrometry according to the English term). Although less precise than the previous SIMS method, such an analysis allows a semi-quantitative analysis of the elements present, in Particularly allows the approximate determination of the atomic ratio O / Nb, by integration of the respective peaks of each of the detected elements, according to well known techniques specific to this method of analysis. The measurement is made at the maximum intensity of the niobium signal, corresponding to the center of the functional layer.

More precisely, the experimental conditions of the measurement carried out are defined below:

The XPS depth profiles of the stacks according to examples 6, 9 and 10 above were acquired using a NOVA® spectrometer distributed by Kratos. XPS spectra are collected using the K _a i _P ha excitation of aluminum (hv = 1486.6eV) of 225W. The binding energy scale is corrected for charge effects by imposing the binding energy of C1 s electrons (CH - aliphatic carbons) at 285 eV. The abrasion source is an Ar + ion gun operating at 2keV with an intensity of 1.15 microA sweeping a weft of 3 x 3mm ² (these operating conditions leading to a corresponding abrasion rate at 3.4 nm / mm in silica). The analysis zone (collection of photoelectrons) is a rectangle of dimensions 300 x 700 microm ² . The take-off angle is 90 ° to the sample surface.

Figure 2 shows the corresponding XPS signals of the elements O and

Nb obtained for the sample according to Example 9.

The results of the analysis of XPS profiles obtained for Examples 6, 9 and 10 are reported in Table 2 which follows.

Table 2 The results show that the layers of niobium deposited in an atmosphere comprising a little oxygen comprise a small amount of oxygen atoms.

It can be seen in the table that the best results in terms of stability of the optical characteristics and conductivity of the glazing before and after the heat treatment are obtained when the niobium layer comprises a limited quantity of oxygen atoms at the core of the layer. niobium, in a manner not yet described to date.

In particular, according to the present invention, the functional layer or layers are characterized by a ratio of the NbO / Nb signal, as measured by a SIMS analysis, of between 1.8 and 2.8, in particular between 2.1 and 2, 8.

The measured data of XPS profiles indicates that the corresponding atomic ratios O / Nb in said functional layers are in the latter case between about 0.14 and about 0.30.

Claims

1. Transparent glazing, constituted by at least one glass sheet provided on at least one of its faces with a coating consisting of a stack of thin layers, including at least one functional layer conferring on said glazing solar control properties, said coating comprising, from the surface of the substrate:

at least one underlayer of a dielectric material,

at least one protective layer of the at least one functional layer vis-à-vis the external environment, made of a dielectric material,

said glazing being characterized in that said functional layer further comprises oxygen, the ratio of NbO / Nb signals in said layer, in SIMS analysis, being between 1, 8 and 2.8.

2. Glazing according to claim 1, wherein the ratio of NbO / Nb signals in said layer is between 2.1 and 2.5.

3. Glazing according to one of the preceding claims, wherein the functional layer has a thickness between 5 and 20 nm.

4. Glazing according to one of the preceding claims, comprising a single functional layer of niobium.

5. Glazing according to one of claims 1 to 3, wherein said coating is constituted by a thin film stack, of which at least two niobium functional layers further comprising oxygen, the ratio of signals NbO / Nb in said layers, in SIMS analysis, being between 1, 8 and 2.8, said coating comprising at least, from the surface of the substrate: at least one underlayer of a dielectric material, a first niobium functional layer, of physical thickness greater than 10 nm and less than 25 nm,

at least one intermediate layer made of a dielectric material; a second functional niobium layer with a physical thickness greater than 5 nm and less than 20 nm;

at least one overlayer of a dielectric material.

6. Glazing according to the preceding claim, wherein the first functional layer has a thickness of between 12 and 25 nm and wherein the second functional layer has a thickness of at least 5 nanometers less than the first, in particular between 6 and 20 nm.

7. Glazing according to one of claims 5 or 6, wherein the intermediate layer between two functional layers is a layer consisting essentially of a nitride or oxynitride aluminum and / or silicon or a mixed oxide zinc and tin, preferably of physical thickness between 30 and 60 nm.

8. Glazing according to one of the preceding claims, wherein said coating comprises two layers of a material selected from the group consisting of Ti, Mo, Al or an alloy comprising at least one of these elements, preferably Ti, disposed with respect to the glass substrate above and below the functional layer and in contact therewith, said layer having a physical thickness of between about 0.2 nm and about 2 nm.

9. Glazing according to one of the preceding claims, comprising a single sub-layer consisting essentially of a nitride or an oxynitride of aluminum and / or silicon, with a physical thickness of between 30 and 60 nm, preferably a layer consisting essentially of silicon nitride, optionally further comprising aluminum.

10. Glazing according to one of the preceding claims, comprising a single overcoat consisting essentially of a nitride or an oxynitride of aluminum and / or silicon, with a physical thickness of between 30 and 60 nm, preferably a layer consisting essentially of silicon nitride, optionally further comprising aluminum.

1 1. Glazing according to one of claims 1 to 9, comprising above the functional layer a succession of a layer essentially of a nitride or an oxynitride of aluminum and / or silicon and a layer of a oxide selected from silicon oxide and titanium oxide, the total optical thickness of said overlayer being between 80 and 1 10 nm.

12. Glazing according to the preceding claim, wherein the succession consists of a layer consisting essentially of silicon nitride and a silicon oxide layer, the physical thickness of the silicon nitride layer being between 40. and 50 nm and the physical thickness of the silicon oxide layer being between 3 and 10 nm.

13. Glazing according to one of claims 1 to 9, wherein the overlayer is constituted by the succession of a layer consisting essentially of silicon nitride and a titanium oxide layer, the physical thickness of the layer. silicon nitride being between 30 and 45 nm and the physical thickness of the titanium oxide layer being between 5 and 15 nm.

14. Glazing according to one of the preceding claims, wherein the total optical thickness of said overlayer is between 90 and 105 nm, in particular between 90 and 100 nm.

15. Glazing according to one of the preceding claims characterized in that it is thermally tempered and / or curved.

16. A stack of layers as described in one of the preceding claims comprising:

at least one underlayer of a dielectric material,

wherein said functional layer further comprises oxygen, the ratio of NbO / Nb signals in said layer, in SIMS analysis, being between 1, 8 and 2.8.