SUBSTRATE PROVIDED WITH A STACK HAVING THERMAL PROPERTIES, HAVING A METALLIC TERMINAL LAYER AND HAVING AN OXIDIZED PRETERMINAL LAYER

Abstract

An substrate is coated on one face with a stack of thin layers including at least one metallic functional layer. The stack includes a terminal layer that is the layer of the stack furthest from the face, which comprises at least one metal M.sub.2 that is a reducing agent in an oxide/metal pair exhibiting an oxidation/reduction potential .sub.2 and the terminal layer is in the metallic state. The stack also includes a preterminal layer that is the layer of the stack located immediately under and in contact with the terminal layer in the direction of the face, which comprises at least one metal M.sub.1 that is an oxidizing agent in an oxide/metal pair exhibiting an oxidation/reduction potential .sub.1 and the preterminal layer is in the at least partially oxidized state. The oxdiation/reduction potential .sub.1 is greater than the oxidation/reduction potential .sub.2.

Claims

1-10. (canceled)

11. A substrate coated on one face with a stack of thin layers having reflection properties in the infrared region and/or in solar radiation comprising at least one metallic functional layer and at least two antireflective coatings, said coatings each comprising at least one dielectric layer, said functional layer being positioned between the two antireflective coatings, said stack comprising: a terminal layer that is the layer of the stack furthest from said face, which comprises at least one metal M.sub.2, said metal being a reducing agent in an oxide/metal pair exhibiting an xidation/reduction potential .sub.2 and said terminal layer being in the metallic state, and a preterminal layer that is the layer of the stack located immediately under and in contact with said terminal layer in the direction of said face, which comprises at least one metal M.sub.1, said metal being a reducing agent in an oxide/metal pair exhibiting an oxidation/reduction potential .sub.1 and said prete iinal layer being in the at least partially oxidized state, wherein said oxidation; eduction potential .sub.1 is greater than said oxidation/reduction potential .sub.2, said oxidation/reduction potentials being measured by a standard hydrogen electrode.

12. The substrate as claimed in claim 11, wherein the at least one metallic functional layer is based on silver or on silver-containing metal alloy.

13. The substrate as claimed in claim 11, wherein said metallic terminal layer exhibits a thickness of between 0.5 nm and 5.0 nm.

14. The substrate as claimed in claim 11, wherein said metallic terminal layer exhibits a thickness of between 1.0 nm and 4.0 nm.

15. The substrate as claimed in claim 11, wherein said preterminal layer exhibits a thickness of between 5.0 and 20.0 nm.

16. The substrate as claimed in claim 11, wherein said preterminal layer exhibits a thickness of between 10.0 nm and 15.0 nm.

17. The substrate as claimed in claim 11, wherein said metallic terminal layer is made of titanium or is a mixture of zinc and tin Sn.sub.iZn.sub.j with an atomic content of tin of 0.1i0.5 and i+j=1.

18. The substrate as claimed in claim 11. wherein said metallic terminal layer is made of titanium or is a mixture of zinc and tin Sn.sub.iZn.sub.j with an atomic content of tin of 0.15i0.45 and i+j=1.

19. The substrate as claimed in claim 11, wherein said preterminal layer is a tin oxide or an oxide of a mixture of metal elements comprising tin.

20. The substrate as claimed in claim 11, wherein said preterminal layer is a tin oxide or an oxide of a mixture of metal elements comprising tin and zinc.

21. The substrate as claimed in claim 20, wherein said preterminal layer is an oxide of a mixture of zinc and tin Sn.sub.xZn.sub.y with an atomic content of tin of 0.3x<1.0 and x+y=1.

22. The substrate as claimed in claim 20, wherein said preterminal layer is an, oxide of a mixture of zinc and tin Sn.sub.xZn.sub.y with an atomic content of tin of 0.5<x<1.0 and x+y=1.

23. The substrate as claimed in claim 11, wherein said preterminal layer is located, starting from the substrate, on a dielectric layer based on silicon nitride that exhibits a physical thickness of between 5.0 and 50.0 nm.

24. The substrate as claimed in claim 11, wherein said preterminal layer is located, starting from the substrate, on, a dielectric layer based on silicon nitride that exhibits a physical thickness of between 8.0 and 20.0 nm.

25. A multiple glazing comprising: at least two substrates which are held together by a frame structure, said glazing producing a separation between an external space and an internal space, in which at least one inserted gas-filled cavity is positioned between the two substrates, and one of the two substrates being the substrate as claimed in claim 11.

26. A process for obtaining a substrate coated on one face of a stack of thin layers having reflection properties in the infrared region and/or in solar radiation comprising at least one metallic functional layer and two antireflective coatings, the, process comprising the following, in order: depositing, on one face of said substrate, a stack of thin layers having reflection properties in the infrared region and/or in solar radiation comprising at least one metallic functional layer and at least two antireflective coatings, said substrate being the substrate as claimed in claim 11; and treating said.stack of thin layers using a source producing radiation, said terminal layer being at least partially oxidized after said treatment.

27. The process as claimed in claim 26, wherein the at least one metallic functional layer is based on silver or n silver-containing metal alloy.

28. The process as claimed in claim 26, wherein the source produces infrared radiation.

29. The process as claimed in claim 26, wherein said treatment is carried out in an atmosphere not comprising oxygen.

Description

[0043] The advantageous characteristics and details of the invention emerge from the following nonlimiting examples, illustrated using the appended figures, which illustrate:

[0044] in FIG. 1, a functional monolayer stack according to the invention, the functional layer being deposited directly on a blocking undercoating and directly under a blocking overcoating, the stack being illustrated during the treatment using a source producing radiation;

[0045] in FIG. 2, a double glazing solution incorporating a functional monolayer stack; and

[0046] in FIG. 3, the light absorption A.sub.L, as percent, of the three series of examples 1, 440 and 5, as a function of the rate r of treatment, in meters per minute.

[0047] In FIGS. 1 and 2, the proportions between the thicknesses of the different layers or of the different elements are not rigorously observed, in order to facilitate the reading thereof.

[0048] FIG. 1 illustrates a structure of a functional monolayer stack 14 according to the invention deposited on a face 29 of a transparent glass substrate 30, in which the single functional layer 140, in particular based on silver or on silver-containing metal alloy, is positioned between two antireflective coatings, the underlying antireflective coating 120 located below the functional layer 140 in the direction of the substrate 30 and the overlying antireflective coating 160 positioned above the functional layer 140 on the opposite side from the substrate 30.

[0049] These two antireflective coatings 120, 160 each comprise at least one dielectric layer 122, 128; 162, 164, 166.

[0050] Optionally, on the one hand, the functional layer 140 can be deposited directly on a blocking undercoating 130 positioned between the underlying antireflective coating 120 and the functional layer 140 and, on the other hand, the functional layer 140 can be deposited directly under a blocking overcoating 150 positioned between the functional layer 140 and the overlying antireflective coating 160.

[0051] The underblocker and/or overblocker layers, although deposited in the metallic form and presented as being metallic layers, are sometimes in practice oxidized layers as 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.

[0052] The antireflective coating 160 located above the metallic functional layer (or which would be located above the metallic functional layer furthest from the substrate if there were several metallic functional layers) terminates in a terminal layer 168, which is the layer of the stack which is furthest from the face 29.

[0053] In addition, a preterminal layer 167 is provided immediately under this terminal layer 168, in the direction of the face 29, this preterminal layer 167 being in contact with the terminal layer located above.

[0054] When a stack 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 inserted gas-filled cavity 15.

[0055] The glazing thus produces a separation between an external space ES and an internal space IS.

[0056] The stack can be positioned as face 3 (on the innermost sheet of the building on considering the incident direction of the sunlight entering the building and on its face directed towards the gas-filled cavity).

[0057] FIG. 2 illustrates this positioning (the incident direction of the sunlight entering the building being illustrated by the double arrow) as face 3 of a stack of thin layers 14 positioned on an internal face 29 of the substrate 30 in contact with the inserted gas-filled cavity 15, the other face 31 of the substrate 30 being in contact with the internal space IS.

[0058] However, it can also be envisaged, in this double glazing structure, for one of the substrates to exhibit a laminated structure.

[0059] Six examples were carried out on the basis of the stack structure illustrated in FIG. 1 and were numbered from 1 to 6.

[0060] For these examples 1 to 6, the antireflective coating 120 comprises two dielectric layers 122, 128; the dielectric layer 122, in contact with the face 29, is a layer having a high refractive index and it is in contact with a dielectric wetting layer 128 positioned immediately under the metallic functional layer 140.

[0061] In examples 1 to 6, there is no blocking undercoating 130.

[0062] The dielectric layer 122 having a high refractive index is based on titanium oxide; it exhibits a refractive index of between 2.3 and 2.7 and which is in this instance precisely 2.46.

[0063] For examples 1 to 6, the dielectric layer 128 is known as wetting layer as it makes it possible to improve the crystallization of the metallic functional

[0064] Layer 140, which is in this instance made of silver, which improves its conductivity. This dielectric layer 128 is made of zinc oxide ZnO (deposited from a ceramic target consisting of 50 atom % of zinc and 50 atom % of oxygen).

[0065] The overlying antireflective coating 160 comprises a dielectric layer 162 made of zinc oxide (deposited from a ceramic target consisting of 50 atom % of doped zinc and 50 atom % of oxygen) and then a dielectric layer 164 having a high index, made of the same material as the dielectric layer 122.

[0066] The following dielectric layer 166 is made of nitride, of Si.sub.3N.sub.4:Al, and is deposited from a metal target made of Si doped to 8% by weight with aluminum.

[0067] For all the examples below, the conditions for deposition of the layers are:

TABLE-US-00001 Deposition Layer Target employed pressure Gas Si.sub.3N.sub.4:Al Si:Al at 92:8 wt % 1.5 10.sup.3 mbar 45% Ar/(Ar + N.sub.2) TiO.sub.2 TiO.sub.2 2 10.sup.3 mbar 90% Ar/(Ar + O.sub.2) Ti Ti 7 10.sup.3 mbar 100% Ar ZnO Zn:O at 50:50 2 10.sup.3 mbar 90% Ar/(Ar + O.sub.2) atom % SnO.sub.2 Sn 2 10.sup.3 mbar 90% Ar/(Ar + O.sub.2) Sn.sub.iZn.sub.j Sn:Zn at 19:81 7 10.sup.3 mbar 100% Ar atom % Sn.sub.xZn.sub.yO.sub.z Sn:Zn at 45:55 2 10.sup.3 mbar 90% Ar/(Ar + O.sub.2) atom % Ag Ag 2 10.sup.3 mbar 100% Ar

[0068] The layers deposited can thus be classified into four categories:

[0069] ilayers made of antireflective/dielectric material, exhibiting an n/k ratio over the entire visible wavelength range of greater than 5: Si.sub.3N.sub.4, TiO.sub.2, ZnO, SnO.sub.2, Sn.sub.xZn.sub.yO.sub.z,

[0070] iimetallic layer made of absorbent material, exhibiting a mean coefficient k, over the entire visible wavelength range, of greater than 0.5 and a bulk electrical resistivity which is greater than 10.sup.6 .Math.cm: Sn.sub.iZn.sub.j, Ti,

[0071] iiimetallic functional layers made of material having properties of reflection in the infrared region and/or in solar radiation; Ag,

[0072] ivunderblocker and overblocker layers intended to protect the functional layer from modification of its nature during the deposition of the stack; their influence on the optical and energy properties is generally not known.

[0073] It has been found that silver exhibits a ratio 0<n/k <5 over the entire visible wavelength range but its bulk electrical resistivity is less than 10.sup.6 .Math.cm.

[0074] In all the examples below, the stack of thin layers is deposited on a substrate made of clear soda-lime glass with a thickness of 4 mm on the Planiclear brand, distributed by Saint-Gobain.

[0075] For these substrates:

[0076] R indicates the sheet resistance of the stack, in ohms per square;

[0077] A.sub.L indicates the light absorption in the visible region in %, measured according to the D65 illuminant;

[0078] I.sub.T indicates the optical inhomogeneities in transmittance; it involves a grade of 1, 2, 3 or 4, assigned by an operator: the grade 1 when no inhomogeneity is perceptible to the eye, the grade 2 when localized inhomogeneities, limited to certain regions of the sample, are perceptible to the eye under intense diffuse illumination (>800 lux), the grade 3 when localized inhomogeneities, limited to certain regions of the sample, are perceptible to the eye under standard illumination (<500 lux) and the grade 4 when inhomogeneities spread over the entire surface of the sample are perceptible to the eye under standard illumination (<500 lux).

[0079] I.sub.R indicates the optical inhomogeneities in reflection; it involves a grade of 1, 2, 3 or 4, assigned by an operator: the grade 1 when no inhomogeneity is perceptible to the eye, the grade 2 when localized inhomogeneities, limited to certain regions of the sample, are perceptible to the eye under intense diffuse illumination (>800 lux), the grade 3 when localized inhomogeneities, limited to certain regions of the sample, are perceptible to the eye under standard illumination (<500 lux) and the grade 4 when inhomogeneities spread over the entire surface of the sample are perceptible to the eye under standard illumination (<500 lux).

[0080] All these examples make it possible to achieve a low emissivity, of the order of 1%, and a high g factor, of the order of 60%.

[0081] The geometric or physical thicknesses (and not the optical thicknesses) in nanometers, with reference to FIG. 1, of each of the layers of examples 1 to 6 are illustrated in table 1 below:

TABLE-US-00002 TABLE 1 Layer Material Ex. 1, 3 Ex. 2, 4-6 168 variable variable 167 variable variable 166 Si.sub.3N.sub.4:Al 25 15 164 TiO.sub.2 12 12 162 ZnO 1 4 150 Ti 0.4 0.4 140 Ag 13.5 13.5 128 ZnO 4 4 122 TiO.sub.2 24 24

[0082] The materials tested for the terminal layers 168 and optionally the preterminal layers 167 of examples 1 to 6, and also their respective thicknesses (in nm), are presented in table 2 below:

TABLE-US-00003 TABLE 2 Layer Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 168 Sn.sub.iZn.sub.j Sn.sub.iZn.sub.j Ti Sn.sub.iZn.sub.j Sn.sub.iZn.sub.j Ti Thickness 4.5 4.5 3 4.5 4.5 3 167 TiO.sub.2 Sn.sub.xZn.sub.yO.sub.z SnO.sub.2 Sn.sub.xZn.sub.yO.sub.z Thickness 15 15 15 15

[0083] It should be remembered that the oxidation/reduction potentials, measured by a standard hydrogen electrode: [0084] for the Ti/TiO.sub.2 pair: 1.63 V [0085] for the Zn/ZnO pair: 0.76 V [0086] for the Sn/SnO.sub.2 pair: 0.13 V.

[0087] For examples 4 to 6, on the one hand, the terminal layer 168 in the metallic state before the treatment comprises at least one metal M.sub.2 (Zn, Ti) which is a reducing agent in an oxide/metal pair exhibiting an oxidation/reduction potential .sub.2 and, on the other hand, the preterminal layer 167 comprises at least one metal M.sub.1 (Sn) which is an oxidizing agent in an oxide/metal pair exhibiting an oxidation/reduction potential .sub.i, and the oxidation/reduction potential .sub.1 is thus greater than the oxidation/reduction potential .sub.2.

[0088] The preterminal layer 167 of examples 4 and 6 is an oxide of a mixture of zinc and tin Sn.sub.xZn.sub.y with an atomic content of tin of 0.3x1.0 and x+y=1, and specifically x=0.45 and y=0.55.

[0089] The preterminal layer 167 of example 5 is a tin oxide deposited in its stable stoichiometric form SnO.sub.2.

[0090] The preterminal layer 167 of example 2 is a titanium oxide deposited in its stable stoichiometric form TiO.sub.2.

[0091] The terminal layer 168 of examples 1, 2, 4 and 5 is a metallic layer consisting of zinc and tin, as Sn.sub.iZn.sub.j, with an atomic content of tin of 0.1i0.5 and i+j=1, and specifically i=0.19 and j=0.81.

[0092] The terminal layer 168 of examples 3 and 6 is a metallic layer consisting of titanium.

[0093] The main optical and energy characteristics of these examples 1 to 6, respectively before treatment (BT) and after treatment (AT), are summarized in table 3 below;

TABLE-US-00004 TABLE 3 A.sub.L R I.sub.T I.sub.R Ex. 1 BT 41.6 2.62 AT 16.5 2.06 3 2 Ex. 2 BT 41.0 2.61 AT 16.0 2.05 3 3 Ex. 3 BT 28.3 2.68 AT 18.3 2.17 2 2 Ex. 4 BT 40.5 2.66 AT 6.4 2.06 1 1 Ex. 5 BT 34.0 2.65 AT 6.8 2.16 1 1 Ex. 6 BT 31.5 2.24 AT 12.3 2.14 1 1

[0094] For examples 1 to 6, the presence of the terminal layer 168, which is metallic before treatment, results in a relatively high absorption A.sub.L at 980 nm (of the order of 30 to 40%), due to the metallic state of these terminal layers before the treatment.

[0095] The treatment consists in this instance of a forward progression of the substrate 30 at a rate of 10 m/min under a laser line 20 with a width of 60 m and a power of 25 W/mm with the laser line oriented perpendicularly to the face 29 and in the direction of the terminal layer 168, that is to say by positioning the laser line (illustrated by the straight black arrow) above the stack and by orienting the laser in the direction of the stack, as visible in FIG. 1.

[0096] The decrease in sheet resistance in the treatment of examples 1 to 3 is of the order of 20%, which is a good result.

[0097] The decrease in sheet resistance in the treatment of example 4 is excellent: 22.5%; the decrease in sheet resistance in the treatment of examples 5 and 6 is not quite so good (respectively 18.4% and 15.7%), while being satisfactory; the emissivity obtained after treatment is low, as desired.

[0098] After treatment and oxidation of the terminal layer 168, examples 1 to 3 exhibit an excessively high light absorption A.sub.L (greater than 15%) and are not optically sufficiently homogeneous, both in transmittance and in reflection, with I.sub.T and I.sub.R values equal to or greater than 2.

[0099] After treatment and oxidation of the terminal layer 168, examples 4 and 5 exhibit an excellent light absorption A.sub.L (of the order of 6.5%) and are optically very homogeneous, both in transmittance and in reflection, with I.sub.T and I.sub.R values equal to 1.

[0100] After treatment and oxidation of the terminal layer 168, example 6 exhibits a light absorption A.sub.L which is a little bit high but is optically very homogeneous, both in transmittance and in reflection, with I.sub.T and I.sub.R values equal to 1.

[0101] Surprisingly, by choosing the preterminal layer according to the invention, despite the presence of oxygen in this layer, the preterminal layer promotes optical stability, both in transmittance and in reflection.

[0102] On the basis of examples 1, 4 and 5, a series of tests was carried out using the same stacks (same materials for layers, same thicknesses) as for examples 1, 4 and 5 but treating them at different treatment rates r; these series are respectively denoted examples 1, examples 4 and examples 5 in FIG. 3.

[0103] This FIG. 3 shows that the absorption A.sub.L after treatment is lower for examples 4 and 5 with a preterminal layer according to the invention under the terminal layer than for examples 1 without a preterminal layer according to the invention under the terminal layer, whatever the treatment rate r.

[0104] In addition, FIG. 3 shows that it is possible to increase the treatment rate by 20% to 50% for examples 4 and 5, up to values of approximately 15 m/minute, without this actually influencing the low absorption after treatment.

[0105] The present invention can also be used for a stack of thin layers having several functional layers. The terminal layer according to the invention is the layer of the stack which is furthest from the face of the substrate on which the stack is deposited and the preterminal layer is the layer located immediately under the terminal layer in the direction of the face of the substrate on which the stack of thin layers is deposited and in contact with the terminal layer.

[0106] The present invention is described in that which precedes by way of example, It is understood that the person skilled in the art is in a position to produce different alternative forms of the invention without, however, departing from the scope of the patent as defined by the claims.