SUBSTRATE PROVIDED WITH A STACK HAVING THERMAL PROPERTIES AND A SUPERSTOICHIOMETRIC INTERMEDIATE LAYER

Abstract

A substrate is coated on one face with a thin-films stack having reflection properties in the infrared and/or in solar radiation including a single metallic functional layer, based on silver or on a metal alloy containing silver, and two antireflection coatings. The coatings each include at least one dielectric layer. The functional layer is positioned between the two antireflection coatings. At least one of the antireflection coatings includes an intermediate layer including zinc oxide Zn.sub.1O.sub.1+x with 0.05<x<0.3 and having a physical thickness of between 0.5 nm and 20 nm, or between 2.5 nm and 10 nm.

Claims

1. A substrate coated on one face with a thin-films stack having reflection properties in the infrared and/or in solar radiation comprising a single metallic functional layer and two antireflection coatings, said coatings each comprising at least one dielectric layer, said functional layer being positioned between the two antireflection coatings, wherein at least one of said antireflection coatings comprises an intermediate layer comprising zinc oxide Z.sub.n1O.sub.1+x with 0.05<x<0.3 and having a physical thickness of between 0.5 nm and 20 nm.

2. The substrate as claimed in claim 1, wherein said intermediate layer comprises zinc oxide Zn.sub.1O.sub.1+x with 0.1<x<0.3.

3. The substrate as claimed in claim 1, wherein said intermediate layer is located in the antireflection coating superjacent to the functional layer.

4. The substrate as claimed in claim 1, wherein said intermediate layer is located in said dielectric coating positioned beneath said metallic functional layer.

5. The substrate as claimed in claim 3, wherein said intermediate layer is located, on another face, directly in contact with a nitride-based dielectric layer having a physical thickness of between 10 and 50 nm.

6. The substrate as claimed in claim 1, wherein said antireflection coating positioned beneath said metallic functional layer comprises a high-index layer made of a material having a refractive index between 2.3 and 2.7.

7. The substrate as claimed in claim 6, wherein said high-index layer has a physical thickness of between 5 and 25 nm.

8. A multiple glazing comprising: at least two substrates which are held together by a frame structure, said glazing providing a separation between an external space and an internal space, wherein at least one intermediate gas-filled space is positioned between the two substrates, one of the two substrates being the substrate as claimed in claim 1.

9. A process for obtaining a substrate coated on one face with a thin-films stack having reflection properties in the infrared and/or in solar radiation comprising a single metallic functional layer and two antireflection coatings, comprising the following steps, in order: the deposition depositing on one face of said substrate the thin-films stack having reflection properties in the infrared and/or in solar radiation comprising the single metallic functional layer and the two antireflection coatings, to form the substrate as claimed in claim 1, treating said thin-films stack using a source that produces radiation.

10. The substrate as claimed in claim 1, wherein the single metallic functional layer is based on silver or on a metal alloy containing silver.

11. The substrate as claimed in claim 1, wherein the physical thickness is between 2.5 nm and 10 nm.

12. The substrate as claimed in claim 1, wherein said intermediate layer comprises zinc oxide Zn.sub.1O.sub.1+x with 0.15<x<0.25.

13. The substrate as claimed in claim 3, wherein said intermediate layer is located directly on an overblocker coating located directly on said functional layer.

14. The substrate as claimed in claim 4, wherein said intermediate layer is located in said dielectric coating positioned directly underneath said metallic functional layer.

15. The substrate as claimed in claim 4, wherein said intermediate layer is located, on another face, directly in contact with a nitride-based dielectric layer having a physical thickness of between 10 and 50 nm.

16. The substrate as claimed in claim 15, wherein the nitride-based dielectric layer is based on silicon nitride Si.sub.3N.sub.4.

17. The substrate as claimed in claim 5, wherein the nitride-based dielectric layer is based on silicon nitride Si.sub.3N.sub.4.

18. The substrate as claimed in claim 6, wherein the high-index layer is based on oxide.

19. The process as claimed in claim 9, wherein the single metallic functional layer is based on silver or on a metal alloy containing silver.

20. The process as claimed in claim 9, wherein the radiation produced in the treating is infrared radiation.

Description

[0040] The details and advantageous features of the invention will emerge from the following nonlimiting examples, illustrated by means of the appended figures that illustrate:

[0041] in FIG. 1, a stack with a single functional layer according to the invention, the functional layer being deposited directly on an underblocker coating and directly beneath an overblocker coating, the stack being illustrated during the treatment using a source that produces radiation; and

[0042] in FIG. 2, a double glazing solution incorporating a stack with a single functional layer.

[0043] In these figures, the proportions between the thicknesses of the various layers or of the various elements are not rigorously respected in order to make them easier to examine.

[0044] FIG. 1 illustrates a structure of a stack with a single functional layer of the prior art deposited on a transparent glass substrate 10, in which the single functional layer 140, in particular based on silver or on a metal alloy containing silver, is positioned between two dielectric coatings, the subjacent dielectric coating 120 located underneath the functional layer 140 in the direction of the substrate 10 and the superjacent dielectric coating 160 positioned on top of the functional layer 140 on the opposite side from the substrate 10.

[0045] These two dielectric coatings 120, 160, each comprise at least two dielectric layers 122, 126, 128; 162, 164.

[0046] Optionally, on the one hand the functional layer 140 may be deposited directly on an underblocker coating 130 positioned between the subjacent dielectric coating 120 and the functional layer 140 and, on the other hand, the functional layer 140 may be deposited directly beneath an overblocker coating 150 positioned between the functional layer 140 and the superjacent dielectric coating 160.

[0047] The underblocker and/or overblocker layers, although deposited in metallic form and presented as being metallic layers, are sometimes in practice oxidized layers since one of their functions, (in particular for the overblocker layer) is to oxidize during the deposition of the stack in order to protect the functional layer.

[0048] This dielectric coating 160 may be terminated by an optional protective layer 168, in particular based on oxide, especially substoichiometric in oxygen.

[0049] When a stack with a single functional layer is used in a multiple glazing 100 of double glazing structure, as illustrated in FIG. 2, this glazing comprises two substrates 10, 30 which are held together by a frame structure 90 and which are separated from one another by an intermediate gas-filled space 15.

[0050] The glazing thus provides a separation between an external space ES and an internal space IS.

[0051] The stack may be positioned on face 2 (on the sheet furthest to the outside of the building when considering the incident direction of the sunlight entering the building and on its face turned toward the gas-filled space).

[0052] FIG. 2 illustrates this positioning (the incident direction of the sunlight entering the building being illustrated by the double arrow) on face 2 of a thin-film stack 14 positioned on an inner face 11 of the substrate 10 in contact with the intermediate gas-filled space 15, the other face 9 of the substrate 10 being in contact with the external space ES.

[0053] However, it may also be envisaged that in this double glazing structure, one of the substrates has a laminated structure.

[0054] Three examples were carried out numbered 1 to 3.

[0055] For these three examples, the antireflection coating 120 subjacent to the functional layer 140 comprises three antireflection layers 122, 124, 128, the layer 122, first layer of the stack and in contact with the face 11, is a layer having an average refractive index; it is made of the nitride Si.sub.3N.sub.4:Al and is deposited from a metallic target doped with 8% by weight of aluminum. The first antireflection layer 122 has an average index; It has a refractive index of between 1.9 and 2.1, and which here is precisely 2.0.

[0056] The second antireflection layer of the antireflection coating 120, the layer 124 has a high refractive index. It is based on titanium oxide; it has a refractive index of between 2.3 and 2.7, and which here is precisely 2.46.

[0057] The third antireflection layer of the antireflection coating 120 is a wetting layer 128 positioned just beneath the metallic functional layer 140.

[0058] In the examples, there is no underblocker coating 130.

[0059] For these examples, the antireflection layer 128 is referred to as a “wetting layer” since it makes it possible to improve the crystallization of the metallic functional layer 140 which here is made of silver, which improves its conductivity. This antireflection layer 128 is made of aluminum-doped zinc oxide ZnO:Al (deposited from a metallic target consisting of zinc doped with 2% by weight of aluminum).

[0060] The superjacent antireflection coating 160 comprises:

[0061] a dielectric layer 162 made of aluminum-doped zinc oxide ZnO:Al (deposited from a metallic target consisting of zinc doped with 2% by weight of aluminum),

[0062] a layer made of silicon nitride Si.sub.3N.sub.4:Al, the layer 164, deposited from a metallic target doped with 8% by weight of aluminum, and

[0063] an oxide-based protective layer 168.

[0064] For all the examples below, the conditions for depositing the layers are:

TABLE-US-00001 Layer Target used Deposition pressure Gas Si.sub.3N.sub.4:Al Si:Al at 92:8 wt % 1.5 × 10.sup.−3 mbar.sup.  Ar/(Ar + N.sub.2) at 45% TiO.sub.z TiO.sub.x 2 × 10.sup.−3 mbar Ar/(Ar + O.sub.2) at 90% Ti Ti 7 × 10.sup.−3 mbar Ar at 100% ZnO:Al Zn:Al at 98:2 wt % 2 × 10.sup.−3 mbar Ar/(Ar + O.sub.2) at 52% except for layer 162 of ex. 2 and 3 NiCr NiCr at 80:20 wt 2 × 10.sup.−3 mbar Ar at 100% Ag Ag 2 × 10.sup.−3 mbar Ar at 100%

[0065] The layers deposited may thus be classed into three categories:

[0066] i—layers made of dielectric material, having an n/k ratio over the entire visible wavelength range of greater than 5: Si.sub.3N.sub.4:Al, TiO.sub.2, ZnO:Al

[0067] ii—metallic functional layers made of material having reflection properties in the infrared and/or in solar radiation: Ag

[0068] iii—overblocker and underblocker layers intended to protect the functional layer against a modification of its nature during the deposition of the stack; their influence on the optical and energy properties is in general ignored.

[0069] It was observed that the silver also has a ratio 0<n/k<5 over the entire visible wavelength range, but its bulk electrical resistivity is less than 10.sup.−6 Ω.Math.cm.

[0070] In all the examples below, the thin-films stack is deposited on a substrate made of clear soda-lime glass having a thickness of 4 mm of the Planilux brand, distributed by SAINT-GOBAIN.

[0071] For these stacks, R indicates the sheet resistance of the stack, measured in ohms per square.

[0072] For these examples, moreover, when the substrate bearing the stack is integrated into a double glazing, it has the structure: 4-16-4 (Ar—90%), that is to say that two glass substrates, each having a thickness of 4 mm, are separated by a gas-filled space consisting of 90% argon and 10% air having a thickness of 16 mm.

[0073] All these examples made it possible to achieve, in this double glazing configuration, a U value, or K value, calculated according to the EN 673 standard, of the order of 1.0 W.Math.m.sup.−2.Math.° K.sup.−1 (this is the thermal transmittance through the glazing; it indicates the amount of heat passing through the substrate in steady state, per unit area and for a unit temperature difference between the face of the glazing in contact with the outside space and the face of the glazing in contact with the inside space).

[0074] The three examples were carried out according to the stack structure illustrated in FIG. 1, but without underblocker coating 130.

[0075] Table 1 below illustrates the geometric or physical thicknesses (and not the optical thicknesses) in nanometers of each of the layers of the series of examples:

TABLE-US-00002 TABLE 1 Layer Material Thicknesses 168 TiO.sub.2 2 164 Si.sub.3N.sub.4:Al 37 162 ZnO:Al 5 150 Ti 1.5 140 Ag 10 128 ZnO:Al 3 126 TiO.sub.2 16 122 Si.sub.3N.sub.4:Al 23

[0076] For example 1, the flow of oxygen for depositing the layer 162 is 400 sccm; this is the flow that makes it possible, under the conditions for depositing this layer, to deposit a layer having a stable stoichiometry of Zn.sub.1O.sub.1. This is the ratio of O/Zn=1 standard for this layer; example 1 therefore constitutes a counterexample of the invention.

[0077] For example 2, the flow of oxygen for depositing the layer 162 is 450 sccm; this flow makes it possible to deposit a layer having the stoichiometry of Zn.sub.1O.sub.1.125. The O/Zn ratio is greater than the standard ratio; the layer deposited is therefore superstoichiometric in oxygen.

[0078] For example 3, the flow of oxygen for depositing the layer 162 is 500 sccm; this flow makes it possible to deposit a layer having the stable stoichiometry of Zn.sub.1O.sub.1.25. The layer deposited is therefore even more superstoichiometric in oxygen than that of example 2.

[0079] Table 2 below states the sheet resistance R, in ohms/square measured for these examples 1 to 3 after the treatment of the stack.

TABLE-US-00003 TABLE 2 Ex. 1 Ex. 2 Ex. 3 R 2.91 2.85 2.79

[0080] Thus, with additional oxidation in the intermediate layer 162 of 12.5% (ex. 2) and of 25% (ex. 3), the sheet resistance of the stack is improved after the treatment of the stack in the sense that it decreases.

[0081] The treatment of the stack consists in passing the stack, after the deposition of all the layers, under a curtain of laser diodes, the diodes being positioned above the stack with reference to FIG. 1 and emitting in the direction of the stack. The diodes emit at the wavelength of 980 nm, each diode emitting over a length of 12 mm and a width of 50 μm. The run speed of the substrate coated with the complete stack is 7 m/minute.

[0082] It is important to note that the intermediate layer according to the invention may be deposited from a ceramic target that comprises the oxygen necessary for achieving the targeted superstoichiometry and in an oxygen-free atmosphere, or may be deposited from a ceramic target that does not comprise all the oxygen necessary for achieving the targeted superstoichiometry and in an oxygen-containing atmosphere.

[0083] The present invention is described in the preceding text by way of example. It will be understood that a person skilled in the art will be able to realize different variants of the invention without otherwise departing from the scope of the patent as defined by the claims.