Layered films for transparent substrates

CA 02315917 2000-06-20 WO 00/24686 PCT / FR99 / 02548 STACK OF LAYERS FOR TRANSPARENT SUBSTRATES The invention relates to a stack of layers for transparent substrates, in particular for glass substrates, with at least one composite layer metal oxides, and in particular produced by reactive cathode sputtering from a metal alloy target containing Zn and Sn.

The substrates carrying the stack can also be based on a transparent material made of organic polymer, and be rigid or flexible.

Rigid polymer substrates are, for example, polycarbonate substrates or certain polyurethanes. It may be polymethyl methacrylate (PMMA).

Flexible substrates are, for example, of the polyethylene tetephthalate (PET) type, a film which is then laminated using two sheets of thermoplastic polymer (of the polyvinyl butyral PVB type) with two glasses.

Patent applications EP 0183 052 and EP 0226 993 disclose stacks of layers with high transparency / low emissivity, in which a functional metallic layer, in particular a thin layer of silver, is placed between two anti-reflection layers of material. dielectric which are the oxidation product of a zinc / tin alloy.

These oxide dielectric layers are deposited by reactive sputtering assisted by magnetic field, using a reactive gas containing oxygen, from a metal target which consists of a Zn / Sn alloy. .

Depending on the Zn: Sn ratio, the composite oxide layer produced in this way will contain a greater or lesser amount of zinc stannate Zn2Sn04, which gives the layer particularly favorable properties, especially in terms of mechanical stability and chemical.

SUBSTITUTE SHEET (RULE 26) CA 02315917 2000-06-20 wo oon4ss6 rcr ~ 'R ~ io2s4s -2 Zn: Sn with a Zn: Sn ratio of 46:54 to 50: 50% by weight are preferably used as a target.

In the sputtering process with industrial coating stacks, sputtering Zn2Sn04 layers from Zn / Sn alloy targets is more difficult than sputtering pure Zn0 or SnOz layers.

This is due to the fact that,: especially at the start of the sputtering process, the material on the target and on the parts of the sputtering chamber leads to insulation effects, the consequences of which are defective products and by therefore products to be rejected.

In addition, alloy targets of this type should be used at reduced sputtering speeds, i.e. reduced electrical power, because the target alloy has a melting point below melting temperatures. of the components, especially in the region of the eutectic composition.

The cooling of such targets must therefore be particularly intensive.

This, in turn, can only be achieved with targets of a particular design, the production of which is comparatively expensive.

The object of the invention is, on the one hand, to further improve the mechanical and chemical properties of the dielectric layers containing the zinc stannate, and, on the other hand, to alleviate the difficulties which occur during the deposition by cathodic sputtering of Zn / Sn alloy oxide layers.

According to the invention, this object is achieved in that the composite layer of metal oxides contains one or more of the elements AI, Ga, In, B, Y, La, Ge, Si, P, As, Sb, Bi, Ce, Ti, Zr, Nb and Ta.

It has been shown that, by the addition according to the invention of said elements, which, without exception, are among the elements in main and subsidiary groups III, IV and V of the Periodic Table, a considerable improvement in the coating properties is obtained. which is important (that is to say in particular the chemical and mechanical durability, the optical quality), combined with an improvement in the efficiency of the sputtering process.

The mixed oxides created by the elements added according to the invention, for example by the addition of Al and Sb, have in particular the composition SUBSTITUTE SHEET (RULE 26) CA 02315917 2000-06-20 WO 00/24686 PCT / FR99 / 02548 -3qualitative ZnO ~ ZnSn03 ~ ZnZSn04 ~ ZnA1z04 ~ ZnSb206, depending on the choice of the quantities of the metals Zn and Sn.

Upon crystallization, some of these oxides form spinel structures, which in themselves crystallize in a particularly dense atomic order.

The improvements in layer properties can probably be explained by the particularly high packing density obtained for the spinel structures obtained by the incorporation of said added elements, while the favorable effect during the deposition by sputtering;: probably had be attributed to the increase in the electrical conductivity of mixed oxides which is obtained by the incorporation of the added elements.

Due to this dense crystal structure, the layers not only have particularly high mechanical and chemical stability, but also prevent diffusion processes in this layer or through this layer.

This reduces the risk of the initiation of modifications of the layer itself or of the other layers of the stack, modifications which are attributed for example to the diffusion of water and oxygen molecules and of Naet, there where applicable when the stack contains Ag), Agy thin layers, especially during heat treatments and storage.

2C For a maximum density spinel structure, it is particularly favorable to have an ionic radius of the added element not differing too much from the ionic radius of Zn2 ~ 'and Sn4 +, which have ionic radii of 0.83 angstrom (Zn2 +) and 0.74 angstrem (Sn4 +), respectively.

This condition is satisfied, in particular, for the elements AI and Sb, with the ionic radii of A13 + = 0.57 ~, and of Sb5 + = 0.62 / ~. On the other hand, as already mentioned, the incorporation of said added elements in the at least partially crystallized layer increases the electrical conductivity of the oxide deposits on the surface of the anodes and on the walls of the deposition chambers, as well as on the surface. of the target itself.

Therefore, the operating times of the target during the sputtering process are, in turn, considerably lengthened, so that not only an improvement in the properties of the layer can be observed, but also an improvement in the coating. sputtering process.

SUBSTITUTE SHEET (RULE 26) CA 02315917 2000-06-20 WO 00/24686 PCT / P'R99 / 02548 -4 The quantity of elements added according to the invention in the composite layer of metal oxides is preferably 0 , 5 to 6.5% by weight, based on the total amount of metal.

The compositions of the composite layer of metal oxides which have been found to be particularly advantageous are those in which, in each case with respect to the total amount of metal, the amount of Zn is from 35 to 70% by weight and the amount of Sn ranges from 29 to 64.5% by weight.

For the production of this composite layer of metal oxides, preferably used alloy targets having from 50 to 70%, in particular 66 to 69% by weight of Zn, from 29 to 50%, in particular 29 to 32% by weight. of Sn, and from 1 to 4% by weight of Al or Sb (in particular 1.5 to 3%).

The composite layers of metals according to the invention can be used particularly successfully in stacks of partially reflective layers with a functional metallic silver layer.

In such layer stacks, they can be used both as an adhesion layer or an astireflection layer, as a wetting / nucleation layer for silver layers deposited on top of it, as a wetting / nucleating layer. as a blocking layer below or above the silver layers and as an underlayer in the region of the top and / or bottom layer of the stack of layers.

Embodiments given by way of indication, relating to stacks of layers according to the invention, will be described below, the properties obtained respectively being compared with the properties of a corresponding stack of layers according to the prior art.

In order to evaluate the properties of the layers, ten different tests were carried out on all the samples, namely A.

Cracking hardness In this case, a needle loaded with a weight is pulled over the layer at a determined speed.

The weight under which traces of cracking become visible is used as a measure of your cracking hardness.

B.

Apparatus cracking hardness when stored in water Same test procedure as for A, but after storing the samples in water at 20 ° C for 30 minutes.

SUBSTITUTE SHEET (RULE 26) CA 02315917 2000-06-20 WO 00/24686 PCT / FR99 / 02548 -5 C.

Erichsen wash test according to ASTM 2486_ Visual evaluation D.

Water condensation test (WCTI The samples are exposed for a period of 140 hours at a temperature of 60 ° C under a relative humidity of 100%.

Visual evaluation.

E.

Znz + leaching The measurement is performed using the plate method according to Kimmel et al., Z.

Glastechnische Berichte 59 (1986) p. 252 and following.

The test provides information on the hydrolytic resistance of Zn-containing layer stacks.

F.

Leaching of Aa The measurement is carried out again using the plate method according to Kimmel et al., Used for the determination of the leaching of Zn2-.

The result of the measurement provides an analytical gauge of the density of the dielectric layers on the Ag layer.

G.

Chlorhydric acid test In this case, the glass sample is immersed for 8 minutes in a solution of 0.01 n HCl at 38 ° C and the percentage loss of emissivity is established.

H.

Hydrochloric acid test Visual evaluation The glass sample is immersed as for G in hydrochloric acid.

The evaluation criterion used is what can be seen on the edge which is submerged.

!.

EMK test This test is described in Z.

Silikattechnik 32 (1981) p. 216 "Untersuchungen zur elektrochemischen Prüfung dünner Metallschichten" (Studies on the electrochemical testing of thin metallic films).

It provides information on the quality of passivation of the cover layer above the silver layer, and on the corrosion resistance of the Ag layer.

The quality of the layer is all the better as the potential difference (in mV) between the stack of layers and the reference electrode is lower.

K.

Water film test SUBSTITUTE SHEET (RULE 26) CA 02315917 2000-06-20 WO 00/24686 PCT / FR99 / 02548 -6 The layer side of the samples is brought into contact for 24 hours with a thin film of water .

The test provides information on the storage stability of coated glass panes stacked in a stack if traces of water enter between the glass panes. The evaluation is carried out visually.

COMPARATIVE EXAMPLE i In an industrial continuous magnetron stack, a stack of layers according to the prior art, with the following sequence of layers, was deposited under usual coating conditions on float glasses of 1 C 6 mm thickness. glass - 40 nm Sn02 - 2 nm CrNi - 10 nm Ag - 4 nm CrNi 37 nm Sn02 - 3 nm Zn2Sn0 ~.

The CrNi layers were deposited by sputtering from a target made of a CrNi alloy, with 20 wt% Cr and 80 wt% Ni in an Ar atmosphere, while the Zn2SnOa layer was deposited by reactive sputtering in an Ar / O atmosphere, from a target made of a Zn / Sn alloy, with 52.4 wt% Zn and 47.6 wt% Sn.

During deposition of the ZnZSnO, ~ layer, unwanted 2C electric arcs occurred at the start of the sputtering process, and these led to coating defects.

In addition, the imprints of the suction cups used in the devices for stacking glass panes were visible on the coated glasses.

The tests referred to under A to K were carried out on the corresponding samples of the coated glasses.

The results of the tests are listed in Table 1, together with the results of the tests carried out in the corresponding embodiment 1 given by way of indication.

Embodiment 1 In the same coating stack, and under the same coating conditions, a stack of layers according to the invention, with the following sequence of layers, was deposited on float glass 6 mm thick. REPLACEMENT (RULE 26) CA 02315917 2000-06-20 WO OO / Z4686 PCT / FR99 / 02548 -7_ glass - 40 nm Sn02 - 2 nm CrNi - 10 nm Ag - 4 nm CrNi 37 nm Sn02 - 3 nm ZnxSn ~ AIZO ~ .

The only difference from Comparative Example 1 was that the top cover layer of the layer stack was applied by reactive sputtering from a target which consisted of an alloy having 68%. by weight of Zn, 30% by weight of Sn and 2% by weight of Al.

During sputtering of this top cover layer, no unwanted electric arcs were observed.

In addition, it was unexpectedly found that no unwanted suction cup imprints were visible with this stack of layers.

The results of the tests obtained with this stack of layers are shown in Table 1 below TABLE 1 Test Comparative example Reaction mode 1 1 A (g) 33 35 B (g) 35 55 C (1000 passes 1 average crack, 1 small round-trip crack) several small cracks D pronounced reddening very slight redness E (mg / 25 ml) 0.19 0.19 F (mg / 25 ml) 0.47 0.03 G (0E in%) 1 0 tranes red no faults I (mV) 95.5 86 no faults no faults r, -. _ ~ .. './V4~ W IIv7LGi ~ GI, Q Na, u, uu ~ dfW water 1, that nempnement layers according to the invention provides better results in almost all the tests than the stack of layers according to the comparative example.

COMPARATIVE EXAMPLE 2 In the same coating stack, under comparable conditions, the following stack of layers according to the prior art has, again, been applied to float glasses 6 mm thick SUBSTITUTE SHEET (RULE 26) CA 02315917 2000-06-20 WO 00/24686 PCT / FR99 / 02548 _ $ glass pane - 40 nm Sn02 - 2 nm CrNi - 10 nm Ag - 4 nm CrNi 34 nm Sn02 - 4 nm ZnZSn04 - 4.5 nm TiOz .

The Zn2SnO4 layer was again deposited by reactive sputtering from a metal alloy target which consisted of 52.4 wt% Zn and 47.6 wt% Sn.

During sputtering of the ZnZSnO4 layer, unwanted arcs were again observed, and these led to coating defects.

The TiO 2 layer was applied by reactive sputtering from a titanium metal target with a DMS cathode and a working gas composed of an Ar / OZ / N mixture.

The tests referred to under A to K were again performed on coated glass samples.

The results are listed in Table 2, together with the results of the tests determined with the samples produced in accordance with the indicative embodiment 2.

Embodiment 2 Under the same coating conditions, with the same coating stack, a stack of layers according to the invention with the following sequence of layers was deposited with the same coating stack on 6 mm float glass. glass thickness - 40 nm SnO2 - 2 nm CrNi - 10 nm Ag - 4 nm CrNi - 34 nm SnO., 4 nm ZnxSnYSbZO "- 4.5 nm TiO2.

The only difference from the comparative example was that, in order to produce the sublayer containing the Zn / Sn mixed oxide, 1a.

The target used was made of an alloy consisting of 68 wt% Zn, 30 wt% Sn and 2 wt% Sb.

No unwanted arcing was observed during sputtering of this alloy.

The samples of coated glass panes were subjected to the tests referred to under A to K.

The results are listed in Table 2 below, together with the results obtained with the samples of Comparative Example 2.

SUBSTITUTE SHEET (RULE 26) CA 02315917 2000-06-20 WO 00/24686 PCT / FR99 / 02548 _g_ TABLE 2 Test Comparative example Implementation mode 2 2 A (g) 30 45-50 B (g) 35 55 C ( 1000 passes 1 medium crack 1 small round-trip crack) D 140 hours weak reddening still lacking after 400 hours E (mg / 25 ml) 0.19 0.15 F (mg / 25 ml) 0.35 0.01 G ( DE in%) 1 0 red tranes no fault I (mV) 80 30 no fault no fault. has better compatibility with the composition layer according to the invention than with the zinc stannate layer of the comparative example.

This manifests itself in a further improvement in the test results, in particular in the substantially better results in the D test (water condensation test) and in a significant improvement in the result of the EMF test.

The result of the leaching of Ag '"is also substantially better, and this stack of layers has, therefore, a remarkable quality as a whole.

COMPARATIVE EXAMPLE 3 In the same coating stack, the following layer stack was once again deposited, under comparable coating conditions, on 6mm thick float glass as comparative samples:

glass - 20 nm Sn02 - 17 nm Zn0 - 1 1 nm Ag - 4 nm Ti02 - 40 nm Sn02.

This stack of layers is a stack of layers which has proven itself in accordance with the prior art.

SUBSTITUTE SHEET (RULE 26) CA 02315917 2000-06-20 WO 00 / Z4686 PCT / FR99 / 02548 - 10 The tests referred to under A to K were also carried out on samples of glass panes coated with this stacking layers.

The test results were, once again, listed in Table 3, together with the test results determined using the samples produced in accordance with Embodiment 3 given as a guide.

Embodiment 3 Under coating conditions comparable to c ~: lles of Comparative Example 3, a stack of layers according to the invention, with the following sequence of layers, was deposited using the same stack of coating on float glasses 6 mm thick glass - 20 nm Sn02 - 17 nm Zn0 - 1 1 nm Ag - 1 nm Ti 3 nm ZnxSn "AIZO ~ - 40 nm SnOZ.

In this case, the composite layer of metal oxides according to the invention serves as a blocking layer together with the very thin layer of Ti placed directly on the silver layer.

The results of the tests carried out on the corresponding samples are also shown in Table 3.

TABLE 3 Test Comparative example Realization mode 3 given as an indication 3 A (g) 4.5 7.5 B (g) 4.5 8 C (350 passes 2 small scratches no back and forth scratches) D 70 hours red spots none fault E (mg / 25 ml) 0.80 0.30 F (mg / 25 ml) 0.60 0.20 G (DE in%? 8 red trans no fault I (mV) 210 130 K no fault no fault SHEET REPLACEMENT (RULE 26) CA 02315917 2000-06-20 WO 00/24686 PCT / FR99 / 02548 - 11 The comparison of the test results shows that improvements Considerable are also observed both in the chemical and mechanical properties in the case where the couc + ~ e according to the invention is used as a blocking layer.

In conclusion, the mixed oxide layers according to the invention make it possible both to facilitate the deposition of the layers and to increase the chemical and mechanical durability of the stacks which incorporate it, especially when they constitute the last or the front. - last layer of the stack.

This type of layer thus makes it possible to make stacks of ZO layers using oxide dielectric layers more resistant, thus bringing them closer to the durability of stacks using nitride dielectrics of the Si3N4 type. It seems that the durability is even better if one chooses to add Sb rather than Al in the mixed oxide.

The invention applies equally well to carrier substrates made of glass and to a transparent material of organic polymer type as mentioned in the preamble.

The layers of the invention can be used as a thin protective overcoat or a thin “blocking” layer (this term designates the fact that the layer in question protects the functional metal layer, for example made of Ag, from deterioration due to the deposition of the substance. upper oxide layer deposited by reactive sputtering in the presence of oxygen), for example in thickness ranges from 2 to 6 nm, or in more significant thickness ranges to serve as a dielectric layer having a significant optical role (for example in a thickness range of 7 to 50 nm.

They can be incorporated in many stacks of thin layers, for example in stacks with an anti-solar or low-emissive functional layer such as silver layers. The stack can contain one or more layers of Ag as described in fes patents EP 638 528, EP 718 250, EP 844 219, EP 847 965, FR 98/13249 and FR98 / 13250.

The stack may contain another type of functional layer, for example made of metal such as an Ni-Cr alloy, or of steel as described in patent EP 511 901 or of nitride such as TiN or ZrN.

SUBSTITUTE SHEET (RULE 26) CA 02315917 2000-06-20 WO 00/24686 PCT / FR99 / 02548 -12 The dielectric layer according to the invention can also form part of an antireflection stack, as described in the patent. EP 728 712 or WO 97/43224, or any other stack 'of layers with an optical, thermal, electrical function using oxide / dielectric layers having refractive indices around 2.

The substrates carrying the stack can be used to make monolithic glazing (single rigid substrate, laminated or multiple with thermal insulation and / or acoustic function of the double-glazing type.

They can be used in the building industry, to equip vehicles (windshields), for display screens ...

By way of illustration, below are stacks that can incorporate the layers of the invention - transparent substrate / SnO 2 / Zn0 / Ag / optional NiCr type blocking layer / SnO 2 / ZnSnO: Al or Sb according to the invention, - transparent substrate / SnOZ / Zn0 / Ag / optional NiCr or Ti type blocking layer / Sn02 / Si02 / Sn02 / ZnSnO: Al or Sb according to the invention.

Sequences can contain two Ag layers as well.

Note further that the levels of added metal relative to Sn and Zn in the target are about the same in the layer obtained from the target in question.

The stacks can of course contain several layers according to the invention, in particular one for its function as a blocking layer and one for its function as a protective overlay.

SUBSTITUTE SHEET (RULE 26)