SUBSTRATE PROVIDED WITH A STACK HAVING THERMAL PROPERTIES AND A SUBSTOICHIOMETRIC 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 tin oxide Sn.sub.xZn.sub.yO.sub.z with a ratio of 0.1≦x/y≦2.4, with 0.75(2x+y)≦z≦0.95(2x+y) and having a physical thickness of between 2 nm and 25 nm, or even between 2 nm and 12 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 tin oxide Sn.sub.xZn.sub.yO.sub.z with a ratio of 0.1≦x/y≦2.4, with 0.75(2x+y)≦z≦0.95(2x+y) and having a physical thickness of between 2 nm and 25 nm.

2. The substrate as claimed in claim 1, wherein said intermediate layer comprises zinc tin oxide Sn.sub.xZn.sub.yO.sub.z with a ratio of 0.55≦x/y≦0.83.

3. The substrate as claimed in claim 1, wherein said intermediate layer is located in said dielectric coating positioned beneath said metallic functional layer, directly on a nitride-based dielectric layer and directly under a wetting layer comprising zinc oxide.

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

5. 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.

6. 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, the process comprising the following steps, in order: 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 in an atmosphere.

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

8. The substrate as claimed in claim 1, wherein the physical thickness is between 2 nm and 12 nm.

9. The substrate as claimed in claim 3, wherein said nitride-based dielectric layer having a physical thickness of between 10 and 50 nm.

10. The substrate as claimed in claim 9, wherein said nitride-based dielectric layer is based on silicon nitride Si.sub.3N.sub.4.

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

12. The substrate as claimed in claim 4, wherein said intermediate layer is located directly on an overblocker coating located directly on said functional layer.

13. 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 2.

14. 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 3.

15. 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 4.

16. The process as claimed in claim 6, wherein the single metallic functional layer is based on silver or on a metal alloy containing silver.

17. The process as claimed in claim 6, wherein the radiation produced in the treating is infrared radiation.

18. The process as claimed in claim 17, wherein the atmosphere in the treating comprises oxygen.

19. The process as claimed in claim 6, wherein the atmosphere in the treating comprises oxygen.

Description

[0047] The details and advantageous features of the invention will emerge from the following nonlimiting examples, illustrated by means of the appended figures that illustrate:

[0048] 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

[0049] in FIG. 2, a double glazing solution incorporating a stack with a single functional layer.

[0050] 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.

[0051] FIG. 1 illustrates a structure of a stack 14 with a single functional layer according to the invention deposited on one face 11 of 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 deposited between two antireflection coatings, the subjacent antireflection coating 120 located underneath the functional layer 140 in the direction of the substrate 10 and the superjacent antireflection coating 160 positioned on top of the functional layer 140 on the opposite side from the substrate 10. These two antireflection coatings 120, 160, each comprise at least one dielectric layer 122, 124, 128; 162, 164.

[0052] Optionally, on the one hand the functional layer 140 may be deposited directly on an underblocker coating 130 positioned between the subjacent antireflection 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 antireflection coating 160.

[0053] 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.

[0054] The antireflection coating 160 located on top of the metallic functional layer is terminated by a terminal layer 168, which is the layer of the stack furthest from the face 11.

[0055] 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.

[0056] The glazing thus provides a separation between an external space ES and an internal space IS.

[0057] 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).

[0058] 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-films 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.

[0059] However, it may also be envisaged that in this double glazing structure, one of the substrates has a laminated structure.

[0060] Two examples were carried out on the basis of the stack structure illustrated in FIG. 1.

[0061] For these two examples, the antireflection coating 120 subjacent to the functional layer 140 comprises three dielectric 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. It has a refractive index of between 1.9 and 2.1, and which here is precisely 2.0.

[0062] The second dielectric layer 126 is an intermediate layer which will be described in greater detail below.

[0063] The third dielectric layer of the antireflection coating 120 is a wetting layer 128 positioned just beneath the metallic functional layer 140.

[0064] In the examples, there is no underblocker coating 130.

[0065] 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).

[0066] In the examples, there is an overblocker coating 150.

[0067] The superjacent antireflection coating 160 comprises a dielectric layer 162 made of aluminum-doped zinc oxide ZnO:Al (deposited from a target identical to that used for the wetting layer 128 and under the same conditions), then a dielectric layer 164 having an average index, made of the same material as the dielectric layer 122.

[0068] This dielectric coating 160 may be terminated with an optional protective layer 168, in particular based on oxide, especially that is substoichiometric in oxygen.

[0069] 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 1.5 × 10.sup.−3 mbar   Ar/(Ar + N.sub.2) at 45% wt % TiO.sub.x TiO.sub.x 2 × 10.sup.−3 mbar Ar/(Ar + O.sub.2) at 90% TiO.sub.2 Ti 2 × 10.sup.−3 mbar Ar/(Ar + O.sub.2) at 35% Ti Ti 7 × 10.sup.−3 mbar Ar at 100% ZnO:Al Zn:Al at 98:2 2 × 10.sup.−3 mbar Ar/(Ar + O.sub.2) at 52% wt % Sn.sub.xZn.sub.yO.sub.z Sn:Zn:Sb at 3 × 10.sup.−3 mbar Ar/(Ar + O.sub.2) at 64% 30:68:2 wt % Ag Ag 2 × 10.sup.−3 mbar Ar at 100%

[0070] The layers deposited may thus be classed into four categories:

[0071] i—layers made of antireflection/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

[0072] ii—intermediate layer made of absorbent material, having a mean k coefficient, over the entire visible wavelength range, of greater than 0.5 and a bulk electrical resistivity which is greater than 10.sup.—6 Ω.cm: TiO.sub.x and Sn.sub.xZn.sub.yO.sub.z

[0073] iii—metallic functional layers made of material having reflection properties in the infrared and/or in solar radiation: Ag

[0074] iv—underblocker and overblocker 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.

[0075] It was observed that the silver 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.cm.

[0076] For both of the examples, 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.

[0077] For both of these examples, [0078] ε indicates the normal emissivity, calculated from the sheet resistance R of the stack which is measured in ohms per square, according to the formula: ε=0.0106 R [0079] A.sub.L indicates the light absorption in the visible in %, measured at 2° under the D65 illuminant; [0080] A.sub.980 indicates the absorption measured specifically at the wavelength of 980 nm, in %, measured at 2° under the D65 illuminant; [0081] T.sub.L indicates the light transmission in the visible in %, measured at 2° under the D65 illuminant; [0082] SF indicates the solar factor, i.e. the ratio, in percent, of the total solar energy entering the room through the glazing to the total incident solar energy; this factor is calculated by considering that the substrate bearing the stack is integrated into a double glazing that 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.

[0083] The two examples were carried out according to the stack structure illustrated in FIG. 1, but without underblocker coating 130.

[0084] Table 1 below illustrates the geometric or physical thicknesses (and not the optical thicknesses) in nanometers of each of the layers of the two examples:

TABLE-US-00002 TABLE 1 Layer Material Ex. 1 Ex. 2 168 TiO.sub.2 2 2 164 Si.sub.3N.sub.4:Al 38 38 162 ZnO:Al 5 5 150 Ti 0.2 0.2 140 Ag 8.5 8.5 128 ZnO:Al 5 5 126 TiO.sub.x SnZnO.sub.x 5 6 122 Si.sub.3N.sub.4:Al 18 18

[0085] Table 2 below summarizes the main optical and energy features of these two examples, respectively when only the substrate 10 alone is considered for the emissivity, the two absorptions and the light transmission and when it is assembled as double glazing, on face 2, F2 as in FIG. 2 for the solar factor SF, respectively before treatment (BT) and after treatment (AT).

TABLE-US-00003 TABLE 2 A.sub.l (%) A.sub.980 (%) ε (%) T.sub.L (%) SF (%) Ex. 1 BT 6.3 13.3 4.9 88.3 64.6 AT 4.6 12.4 3.9 90 64.4 Ex. 2 BT 9.6 19 4.8 85.4 65.7 AT 4.7 12.9 4 90 64.8

[0086] Thus, the optical and energy properties of example 2 according to the invention are substantially identical to that of the reference example 1.

[0087] The treatment of the stack consists, for both examples, in passing the stack, after the deposition of all the layers, under a curtain 20 of laser diodes, the diodes being positioned above the stack with reference to FIG. 1 and emitting in the direction of the stack (emission illustrated by the straight black arrow). The diodes emit at the wavelength of 980 nm, each diode emitting over a length of 12 mm and a width of 45 μm. However, for example 1, the run speed of the substrate coated with the complete stack is 11 m/minute whereas for example 2 it is 22 m/minute.

[0088] It is particularly surprising that an intermediate layer located in said dielectric coating 120positioned underneath said metallic functional layer 140 can be “re-oxidized” by the subsequent treatment of the complete stack using a source that produces radiation and in particular infrared radiation.

[0089] When this intermediate layer is, as in the case of the example above, directly on a nitride-based dielectric layer having a physical thickness of between 10 and 50 nm and directly beneath a wetting layer comprising zinc oxide, then this intermediate layer may also have a smoothing effect, such as that disclosed in international patent application WO 2007/101964.

[0090] An intermediate layer deposited from a target made of Sn:Zn at 56.5:43.5 wt % was also tested and gave similar results.

[0091] 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 oxygen stoichiometry and in an oxygen-free atmosphere, or may be deposited from a metallic target that does not comprise all the oxygen necessary for achieving the targeted oxygen stoichiometry and in an oxygen-containing atmosphere.

[0092] 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.