Temperable Low-e-coating system, method for fabrication and Low-e-glasproduct with layered coating

The invention relates to a temperable low-e layer system, which can be applied to a substrate and a layer structure of having at least one silver layer.

The invention further relates to a process for preparing a temperable low-e layer system and thus produced low-e glass product.

Coated substrates found in various Technology areas application. The used Layer systems serve the optical, chemical and / or mechanical properties of substrates to be improve.

The invention relates in particular to transparent Substrates with an at least partially translucent layer system are provided. Both transparent substrates may be, for example, Slices of plastic or glass act. The term glass is here to be considered in a general sense and includes also glassy materials such vitrokristalline substances.

In the coating of transparent substrates, it is known, by appropriate selection of multiple layers a Layer system with low emissivity and desired Transmission or reflection values ​​of the coated to achieve substrate. Such coating systems and Glass products are designated by the term "low-e" whereby the desired low emissivity of the product is expressed.

Will low-e coating systems, for example, Insulating glass used can thereby be the U-value reduce from coated glass such spaces. The light transmittance should be carried in both directions only little hampered, so that a high light transmission is sought. In addition to the reflection color of the Glazing set as possible in a large area, but preferably be color neutral.

To achieve the desired optical properties in a low-e layer system usually at least one Functional layer of a reflective material used. In particular, takes silver for use. The total coating system is designed so that the Permeability for most radiation in the visible Region of the spectrum is permitted while the largest Part of the infrared radiation is reflected.

A silver layer used in a low-e layer system is typically of at least two further layers enclosed, for example, as a blocker and Upper blockers can be referred. A transparent Upper blocker is required to the silver layer before chemical and / or mechanical influences during Production or in the use of low-e glass products to protect. The top blockers may also protect against UV radiation be used. In addition to other layers as For example, anti-reflection coatings is the Upper blocker over the silver layer on the said substrate opposite side. The sub-blockers is located at Silver layer on the substrate-facing side and improves the electrical properties of the above contained silver layer. Further, the sub-Blocker protects the silver, for example, prior to diffusion of impurities which can become embedded in the silver.

As the lower and upper blockers may different layers be used. Known examples are top blocker from NiCrO_x or ZnO. For example, describe the International patent application WO 00/37384 and US Patent US 6,398,925 B1 describes a method in which a Silver layer having an upper blocker from a ZnO ceramic is coated, and the ZnO ceramic layer coated silver layer on a glass sheet. The ZnO ceramic layer is assisted by a ceramic ZnO target sputtered. As a blocker is the use of ZnO also known as, for example, in US Patent US 5,962,115 is described.

Increasingly, it is necessary to low-e coating systems thermally treated. This bias increases gives flexural strength of the glass sheet and their specific Safety properties. In the manufacture and However, further processing of low-e glass products, there is a Problem that an educated layer structure by various physical and / or chemical processes changed, and a change in the optical thermal properties of the layer system leads. At the Annealing of low-e coating systems is the system in a certain atmosphere heated, wherein a diffusion of can be carried out oxygen in the layer structure, resulting in a Oxidation of the silver layer leads. The oxygen may for example, from the atmosphere above the surface of the Layer system or from other areas of the system in the and thus diffuse system in the silver layer. Further , sodium ions or other impurities from example the glass substrate into the layer structure and thus also in the silver layer penetrate.

Such diffusion processes result in a change of Reflection color of the layer structure, as this in particular, the optical and electrical properties of change layer of silver used. Furthermore also causes the change in the crystal structure of Silver layer, a color change, the so-called Color Shift. has a layer structure with a layer of silver Thus before a tempering a different color after Annealing, and this color shift is in the production to consider and further processing of low-e glasses.

It is known, the color shift occurring compensate by a layer system is designed so that before annealing a certain degree of coloration having. The degree of coloring is adjusted so that by the color shift during the subsequent tempering process a color neutral glass product yields. Such methods have However, the disadvantage that the annealing in kilns with must be carried out specific parameters, otherwise the solid color neutrality of the end product is not can be achieved reliably and reproducibly. Changes in the required parameters for example, on the surface of a glass product lead to deviations of the color neutrality, whereby a produced Layer structure for use in glass construction becomes useless.

The German patent DE 198 52 358 C1 proposes to Achieve the desired optical properties of low-e layer system in front, over the silver layer, an Al alloy, a metal oxide such as SnO₂, Bi₂O₃, TiO₂ or ZnO and a ZnO-containing mixed oxide with spinel structure as Upper blocker has. is below the silver layer also a metal oxide from the group mentioned, ZnO or Zn.

From the German patent DE 197 19 543 C1 is further a thermally resilient low-e layer system is known a lower and an upper antireflection coating of a or more metal or semiconductor compounds, a Functional layer of silver and immediately below the Silver layer a layer of doped with Al and Si comprising zinc oxide, which layer by reactive Sputtering of a metallic target of a was prepared Zn-Al-Si alloy.

The object of the invention is a temperable low-e layer system be applied to provide on a substrate, which after a tempering low emissivity and has a high light transmission, wherein the layer construction after the annealing process is neutral in color and a low Sheet resistance R comprises. In particular, the Layer system in a wide, for tempering glass relevant temperature range a high stability with respect include its properties. This is to be achieved, that even with different furnace parameters reproducible coating properties are achieved.

Object of the invention is a layered structure consisting of defining from different layers of material, the the diffusion of impurities from outside into the Layer system and the diffusion of the different materials the layer system with each other as far as possible prevented.

The object of the invention is also a process for the Production of such a layer system, and using provide for a low-e glass product.

According to the invention, this object is by the features of Claims 1, 5, 18, 20, 23, 26 and 27 dissolved. advantageous Developments of the invention are found in the Subclaims.

The invention temperable low-e layer system is on a substrate be applied and has a layered structure with at least one silver layer. Between the substrate and Silver layer are at least one diffusion barrier layer, a first anti-reflection layer and a sub-blockers disposed, and starting from the substrate over the Silver layer is at least one top blocker and a second Antireflection coating disposed. Here, the first Anti-reflection layer has a higher refractive index than the second anti-reflection layer. The main component of the Under blocker and the top blocker is ZnO_xWherein aluminum doped ZnO_x (ZnAlO_x) Is preferred. This means that the layer of more than 50% of ZnO_x consists.

The diffusion barrier layer consists at least 50% from SnO_x, It has proven particularly advantageous to use a Diffusion barrier layer of nearly 100% SnO_x use but Mixtures of at least 50% SnO also_x and a Remaining constituent of ZnO_x result in a layer system, which meets the object of the invention. In which Balance being ZnO_x it is preferably also by aluminum-doped ZnO_xSo that the layer in a particularly preferred embodiment of the invention from ZnSnAlO_x consists. Above the top of the second blocker and Antireflection coating, a protective layer of ZnSnAlO_xbe arranged. In a further advantageous Embodiment of the invention, both the Under blocker and the top blocker and the Diffusion barrier layer of ZnO_xWherein also ZnAlO_xis preferred.

The first anti-reflection layer between the substrate and Silver layer consists of TiO₂ and has a thickness of 5-55nm, preferably from 10-25nm. The refractive index of the first Antireflection coating is 2.5. Over the first Antireflection coating of TiO₂ There is a SnO_x-Layer, which acts as an inner diffusion barrier layer. The second anti-reflection layer over the silver layer is of SnO₂ and has a thickness of 20-60nm, preferably 25-45nm of. The refractive index of the second anti-reflection layer is in a preferred embodiment of the invention at about the second

encompassed by the invention are further Double silver layer systems in which above the Upper blocker and the second antireflection a second silver layer. Under the second Silver layer is preferably a second Under Blocker from ZnAlO_x, About the second silver layer are analogous to a second top blocker, a third Anti-reflection layer and a protective layer. The preferred Materials comply with the materials already described Simply the silver system.

The invention further comprises a process for preparing a temperable low-e layer system on a substrate, in which a substrate is provided, to which the various functional layers are applied. The The method includes providing a substrate, and Depositing a diffusion barrier layer that is at least 50% of SnO_x consists. Further, a first Anti-reflection layer, an inner diffusion barrier layer of SnO_x and a sub-blockers applied, the Main component of the sub-blocker ZnO_x is. The method further comprises applying a silver layer and a Upper blocker, whose main component is ZnO_x, Furthermore depositing a second anti-reflection layer, wherein the first anti-reflection layer has a higher refractive index than the second.

It has proved advantageous that the individual layers applied by sputtering of the system. especially the are diffusion barrier layer and / or the blocking layers preferably deposited by sputtering. If it is thereby to ZnAlO_xLayers, the sputtering from a Aluminum doped ZnO_x-target (ZAO target) advantageous. Are to further improve the high-temperature stability ZnSnO_x- Preferred but ZnSnAlO_xLayers employed, each layer metallic of aluminum doped ZnSn- or ZnSnAl target are sputtered. Also SnO_xLayers are preferably metallic from a Target sputtered.

The invention further includes a low-e glass product with the described layer system on a substrate. The Layer system can be annealed to a glass product, which identifies the desired properties. It can However also used unannealed, as well as the untreated layer structure already advantageous Properties. For example, can already be at the untempered layer structure at neutral reflection and Transmission over conventional low-e products a recognize increasing the transmittance by about 2% to ≥89%. The ε normal emissivity_n is this uncured products at about 4%.

After an annealing process leads to the invention Layer system to a color-neutral glass product with a low emissivity. The achieved normal emissivity lie, depending on the choice of the thicknesses of the Silver and antireflection coatings in the range of ε_n= 2-4%. At the same time, the tempered layer system has a high Transmission on of ≥90%. The production is a facilitates color neutral glass product characterized in that the Color shift during tempering is substantially reduced. The Layer system further has an advantage that to be carried out annealing not in ovens with very narrow must be made parameters to a reproducible product to accomplish. The properties of the layer system are rather in a relevant for the curing of glass Temperature range as far as possible constant, so that Variations of certain parameters not to cause serious deterioration of the product. The Production of tempered glass products is so much facilitated.

One of a ZAO target abgesputterter Under Blocker acts Further, below the silver layer as a seed layer comprising the crystalline growth of the silver layer promotes what is advantageous to the manufacturing process of the layer system effect. The doping of aluminum to a ZnO_x-target also brings with it the advantage that the Sputtering properties are improved, so that the material less prone to so-called arcing. Further, the thickness the silver layer can be reduced, whereby a Cost reduction in the production of low-e glazing can be achieved.

The embedding of the first anti-reflection layer of TiO₂between the diffusion barrier layer and a SnO₂-Layer serves to protect the TiO₂Layer upon annealing. Thus, the Titanium oxide protective coating and can not, for example, in the Silver layer diffuse. Also, the diffusion of zinc from the sub-blockers in the TiO_xLayer is thus prevented. This is necessary because of the lower by a blocker Transitioning from Zn in the TiO_xLayer would dissolve and thus under the silver layer no egg and protective layer more were available. The inventive Layer structure are thus not only sodium ions from prevented from the glass substrate into the layer system penetrate, but it also causes the preservative TiO_x-Layer. Only then can the high refractive index of the TiO_xLayer advantageously even after a tempering process be used.

Further advantages, special features and practical Further developments of the invention result from the Claims and the following description of preferred Embodiments with reference to the figures.

The figures show:<dl tsize="6"><dt>Fig. 1</dt><dd>A particularly preferred embodiment of the inventive low-e layer structure;</dd><dt>FIG. 2</dt><dd>the change in the surface resistance of the Layer system of the invention at a thermal treatment in comparison with other Layer systems;</dd><dt>Fig. 3</dt><dd>the opacity of the layer system of the invention during a thermal treatment in comparison to other layer systems; and</dd><dt>Fig. 4</dt><dd>the color shift of the layer system according to the invention during a thermal treatment in comparison to other coating systems.</dd></dl>

Fig. 1 shows a particularly preferred embodiment the low-e layer system according to the invention. shown is following particularly preferred layer sequence:<tables><table><tgroup cols="3"><tbody><row><entry align="center">10</entry><entry align="left">substratum</entry><entry align="left">(1,5-20mm)</entry></row><row><entry align="center">20</entry><entry align="left">SnO_x, ZnAlO_x or ZnSnAlO_x</entry><entry align="left">(5-15nm)</entry></row><row><entry align="center">30</entry><entry align="left">TiO₂</entry><entry align="left">(5-55nm)</entry></row><row><entry align="center">40</entry><entry align="left">SnO₂</entry><entry align="left">(5-15nm)</entry></row><row><entry align="center">50</entry><entry align="left">ZnAlO_x</entry><entry align="left">(5-10Nm)</entry></row><row><entry align="center">60</entry><entry align="left">ag</entry><entry align="left">(8-17nm)</entry></row><row><entry align="center">70</entry><entry align="left">ZnAlO_x</entry><entry align="left">(4-25nm)</entry></row><row><entry align="center">80</entry><entry align="left">SnO₂</entry><entry align="left">(20-60nm)</entry></row><row><entry align="center">90</entry><entry align="left">ZnSnAlO_x</entry><entry align="left">(5-15nm)</entry></row></tbody></tgroup></table></tables>

It is essential that it is asymmetric to a Layer structure is, in which between a substrate 10 and a silver layer 60, a first anti-reflection layer 30 having a relatively high refractive index, and over the silver a second anti-reflection layer 80 with a lower Refractive index is disposed. The substrate 10 is transparent, and it is preferably a Glass substrate. Typical thicknesses of the substrate are between 1,5-20mm.

In the first anti-reflection layer 30 is preferably a TiO₂-Layer. There may be other suitable materials such as Nb₂O₃ and their Mixed oxides such as TiNbO_x be used. Of the Refractive index of the first anti-reflection layer is in the Order of magnitude of 2.2 to 2.6, preferably is a Refractive index of about 2.5. Through this high-index Material in the base layer can be thicker entspiegeln silver layers so that the a * value in the L * a * b * system is negative and thus no undesired coloring in positive a * range is generated. The second Antireflection coating 80 is preferably made of SnO₂ and has a refractive index in the order of 1.9 to 2.1, where a refractive index of approximately 2 is preferred. The thickness of the second anti-reflection layer is preferably between 25-35nm.

The use of TiO₂ the first anti-reflection layer under the silver has the disadvantage that TiO₂ in the High-temperature behavior of the diffusion of Na ions into the Layer system only slightly suppressed. The diffusion of Na ions can not therefore sufficiently from the glass substrate be prevented. To the optical advantages of high Refractive index of TiO₂ still be able to use is, According to the invention from the substrate 10 starting between the Substrate and the TiO₂Layer 30 is a diffusion barrier layer 20. The diffusion barrier layer consists preferably from SnO_x, ZnSnO_x or ZnSnAlO_x, This layer is used primarily used as a diffusion barrier, while a Entspiegelungsfunktion not in the foreground.

Since the layer is less used for anti-reflection, but for this function serve other specially designed layers can be realized thinner layers than for example, conventional ZnO_x- Or ZnSnAlO_x-Layers beneath a layer of silver is the case. Typical thicknesses for ZnO_x- Or ZnSnAlO_xlayers below a silver layer are of the order of 25-50nm, while the thickness of the diffusion barrier layer 20 is preferably is of the order of 5-15nm.

It has proven to be especially effective, the Diffusion barrier layer 20 applied by sputtering, wherein depending on the layer material, metallic or ceramic targets be used. The sputtering method may vary according to Layer material can be varied. For the sputtering of a SnO_x-, ZnSnO_x- Or ZnSnAlO_xLayer is the reactive DC sputtering from a corresponding metallic target advantageous during a ZnAlO_xLayer sputtering of a ceramic target (ZAO target) non-reactive in the DC method is appropriate.

About the TiO_xLayer is a SnO_xLayer 40 and directly beneath the silver layer 60 is a lower blocker 50 arranged. The SnO_xLayer prevents the diffusion of TiO_x in ZnAlO_x and reverse diffusion processes and serves thereby obtaining the properties of the lower Antireflection coating, the sub-blocker and the Silver layer. The sub-blocker is preferably made of ZnAlO_x and is expediently likewise ceramic of a ZAO target sputtered.

If no diffusion barrier layer 20 directly on the substrate arranged sodium ions in the layer system penetrate, but are through the inner Diffusion barrier layer 40 from diffusing into the Under blocker 50 and prevented in the silver layer. However, According to the invention two barrier layers in the form of Diffusion barrier layer 20 and the inner Diffusion barrier layer 40 is used, so that both the Diffusion from the glass substrate and the out diffusion can be effectively prevented in the silver layer into it.

According to the invention over the silver layer a top blocker 70 arranged. This layer preferably also consists of ZnAlO_xWhich sputtered from a ceramic ZAO target was . The thickness of the upper blocker is of the order of 2-25nm. The use of a ZnAlO_xlayer as Upper blocker causes over conventional blockers for example NiCrO_x a substantial improvement in the Properties of the layer system, as they at annealing the diffusion of oxygen and other atoms in the silver effectively prevented.

Above the upper blocker 70 is the second anti-reflection layer 80 arranged and it can further functional layers be deposited. For this purpose at least one a hard Protective layer 90 to protect against the layer system mechanical and chemical influences. This cover layer can for example ZnSnAlO_x made that a metallic target was sputtered.

encompassed by the invention are further double silver systems with at least two silver layers. The layer sequence with a Double silver system is for example the following: Substrate / SnO_x/ TiO_x/ SnO_x/ ZnAlO_x/ Ag / ZnAlO_x/ SnO_x/ (ZnSnAlO_x) / ZnAlO_x/ Ag / ZnAlO_x/ SnO_x/ ZnSnAlO_x

The layer structure between the substrate and the first Silver layer corresponds to the layer structure of the Simply silver system, wherein the first diffusion barrier layer alternatively over the substrate on SnO_x also from ZnAlO_x. ZnSnO_x or ZnSnAlO_x may exist. Over the first Silver layer is the first top blocker from ZnAlO_xand this is followed by the second anti-reflection layer of SnO_x, On the ZnSnAlO_xProtective layer of silver Simple Systems This second anti-reflection layer may consist of technical View be dispensed with. In the second Antireflection coating is then followed by a second sub-blockers in Form a ZnAlO_x-Layer. In a second Silver layer, a second upper blocker from ZnAlO_x, Third Antireflection coating of SnO_x and finally a Protective layer of ZnSnAlO_x applied.

To apply the layers of the layer system can various known methods for deposition of material come on a substrate for application. In the methods it is, for example, CVD or PVD process. In a particularly preferred embodiment of the invention are represented by the individual layers of the structure Sputter deposited.

Thus, by the above-described layer structure on a substrate generates a low-e coating system for use in glass construction be that at an annealing a reproducible Color Shift passes. The production-related color shift, which caused among others by the crystallization of silver is, is defined as a neutral layer problems can be adjusted.

It was found that the Surface resistance of the glass product during annealing decreased, while he in known layer systems typically elevated. By reducing the surface resistance the U-value of the glass product is also reduced, which for the production of glazing units especially is advantageous. The particular advantage of the described herein The layer system is that due to the asymmetric Layer structure, the silver layer is not reduced and the Surface resistance must be increased in order according to the Annealing to obtain a color-neutral product. It can be even thicker layers of silver after Annealing color neutral entspiegeln, so that by the Annealing improved electrical conductivity of the Silver to improved product properties fully benefit comes. Depending on the application can be emissivity of ε_n= 2-4% achieve.

The following tables show the change in the Sheet resistance R [Ω], the turbidity and the color shifts dE below for various coating systems a), b) and c) various conditions. All examined coating systems reported ZnAlO_x-Oberblocker Over the silver layer, while the diffusion barrier layer was varied. The rest Layer structure corresponds to the structure described a Simple silver system as in Fig.1. The ZnAlO_x-Oberblocker was thereby sputtered from a ceramic ZAO target.

The Schichtaubau a) has a ZnAlO_x-Diffusionsperrschicht , which likewise ceramic of a ZAO target was sputtered. The composition of the layer in wt .-% is approximately 98% zinc and 2% aluminum. The layer structure in b) has an SnO_x-Diffusionssperrschicht On which of a metallic target is sputtered. Of the Layer structure in c) has a ZnSnAlO_x-Diffusionssperrschicht on, also by a metallic target was sputtered. The composition the layer in wt .-% is about 68% zinc, 30% tin and 1.2% aluminum.

Table 1 shows the values ​​obtained at a Annealing is in an ESG oven.<tables><table><tgroup cols="5"><tbody><row><entry align="left">sample</entry><entry align="left">Diffusion barrier layer</entry><entry align="left">R_{in front} [Ω]</entry><entry align="left">R_after [Ω]</entry><entry align="left">.DELTA.R [Ω]</entry></row><row><entry align="left">a)</entry><entry align="left">ZnAlO_x</entry><entry align="center">4.23</entry><entry align="center">2.60</entry><entry align="center">-1.63</entry></row><row><entry align="left">b)</entry><entry align="left">SnO_x</entry><entry align="center">4.11</entry><entry align="center">2.62</entry><entry align="center">-1.49</entry></row><row><entry align="left">c)</entry><entry align="left">ZnSnAlO_x</entry><entry align="center">4.14</entry><entry align="center">2.50</entry><entry align="center">-1.64</entry></row></tbody></tgroup></table></tables>

Table 2 shows the values ​​obtained at a Annealing at 620 ° C and a plateau time of 10 min in a muffle furnace. In addition, the haze and were Color shift dE determined.<tables><table><tgroup cols="7"><tbody><row><entry align="center">sample</entry><entry align="center">Diffusion barrier layer</entry><entry align="center">R_{in front} [Ω]</entry><entry align="center">R_after [Ω]</entry><entry align="center">.DELTA.R [Ω]</entry><entry align="center">Haze [%]</entry><entry align="center">dE </entry></row><row><entry align="center">a)</entry><entry align="center">ZnAlO_x</entry><entry align="center">4.09</entry><entry align="center">2.92</entry><entry align="center">-1.17</entry><entry align="center">0.11</entry><entry align="center">6.99</entry></row><row><entry align="center">b)</entry><entry align="center">SnO_x</entry><entry align="center">4.03</entry><entry align="center">2.87</entry><entry align="center">-1.16</entry><entry align="center">0.30</entry><entry align="center">5.19</entry></row><row><entry align="center">c)</entry><entry align="center">ZnSnAlO_x</entry><entry align="center">4.05</entry><entry align="center">2.80</entry><entry align="center">-1.25</entry><entry align="center">0.08</entry><entry align="center">7.22</entry></row></tbody></tgroup></table></tables>

Table 3 shows the values ​​obtained at a Annealing at 650 ° C and a plateau time of 10 min in a muffle furnace. In addition, also were the cloudiness and the color shift dE determined.<tables><table><tgroup cols="7"><tbody><row><entry align="center">sample</entry><entry align="center">Diffusion barrier layer</entry><entry align="center">R_{in front} [Ω]</entry><entry align="center">R_after [Ω]</entry><entry align="center">.DELTA.R [Ω]</entry><entry align="center">Haze [%]</entry><entry align="center">dE</entry></row><row><entry align="center">a)</entry><entry align="center">ZnAlO_x</entry><entry align="center">4.12</entry><entry align="center">3.57</entry><entry align="center">-0.55</entry><entry align="center">0.54</entry><entry align="center">9.05</entry></row><row><entry align="center">b)</entry><entry align="center">SnO_x</entry><entry align="center">3.99</entry><entry align="center">2.98</entry><entry align="center">-1.01</entry><entry align="center">0.73</entry><entry align="center">6.39</entry></row><row><entry align="center">c)</entry><entry align="center">ZnSnAlO_x</entry><entry align="center">4.13</entry><entry align="center">3.05</entry><entry align="center">-1.08</entry><entry align="center">0.31</entry><entry align="center">7.81</entry></row></tbody></tgroup></table></tables>

From the tables it can be seen that by all Combinations of diffusion barrier layers with a ZnAlO_x-Layer as a reduction in the upper blocker Sheet resistance R takes place during annealing, so that the inventively selected top blocker positive Influence on the desired properties of the layer system Has. A diffusion barrier layer between the substrate and Silver layer can reinforce this positive effect yet. It should be noted for all furnace conditions that the Color shift at a SnO_xLayer is the lowest. The Turbidity is in this layer on the other hand the highest.

In FIG. 2, the change in sheet resistance for .DELTA.R various low-e coating systems applied over the Temperature during annealing in two pictures shown. In the figure above is the Temperature range of 0-650 ° C, and in the figure below applied a restricted range of 600-650 ° C. there the curve a with filled circles measuring point Standard low-e layer system without diffusion barrier but with ZnAlO_x Upper represents Locker, wherein the sheet resistance as in all other coating systems in the process, first drops sharply and then from about 550 ° C again strongly increases, so that at the end of measurement, a magnification of the Resistance is noted. The second picture is to found that the increase in resistance very constant , and between 600 ° C and 650 ° C, a sharp change of about -1.2 to +0.2 done. This means that a slight Changing the temperature of a major change in the means surface resistance.

When layer system with a ZnAlO_x-Diffusionssperre (Solid line) increases the sheet resistance by the not anneal to, but he is after the process less than before. If the sheet resistance as a measure of the quality of the product to put the glass product, means its reduction an improvement of the glass product by using a ZnAlO_x-Diffusionssperre. The second Figure it can be seen that the change of Surface resistance in a range of 600 ° C to 640 ° C is largely constant before then increases from 640 ° C. Changes in temperature in this range change Sheet resistance thus only slightly, whereby good Reproducibility of layer systems with ZnAlO_x-Diffusionssperre is achieved.

A ZnSnAlO_x-Diffusionssperre As with by a line unfilled circles measuring point is illustrated, reduces the Surface resistance as far as an after annealing SnO_x-Diffusionssperre, Dotted with a line is shown. The reduction by these layers is compared to the other layer systems most, wherein determine is that both curves in the range between 600-650 ° C are largely constant.

In Fig. 3, the haze is in% for these low-e coating systems shown in two pictures. In the upper Figure in turn is the temperature range of 0-650 ° C and in the figure below, a limited range of 600-650 ° C applied. The standard low-E layer system without but diffusion barrier with ZnAlO_x-Oberlocker Leads to strong increase in the turbidity after the annealing process, while the other layer systems a much lower haze to cause. Since the turbidity, the quality of a glass product impaired, provide the specified Alternatively, layer systems represents a significant improvement. It should be noted that the turbidity in a only slightly the range between 600-650 ° C changed what turn good reproducibility of the glass product with brings. Conventional systems without diffusion barrier hand out during the annealing process a strong Increase in turbidity, so that a slight change in the can temperature cause a haze which the makes glass product unusable.

In FIG. 4, the color shift dE for the different Layer systems applied in two pictures. The standard low-e coating in turn undergoes the strongest color shift, during all coating systems with a diffusion barrier in particular in the temperature range 600-650 ° C lower Color shift through. Without strong increase are also those Curves over the temperature far more constant, which in turn the reproducibility supported. It should be noted, that the SnO_x-Diffusionssperrschicht By far the smallest brings color shift with it.

All figures make it clear that the inventive low-e layer system on a substrate in a for curing relevant of glass temperature range a high constancy with respect to its properties. It is thereby achieved, that even with different furnace parameters reproducible coating properties can be obtained.

LIST OF REFERENCE NUMBERS

<dl tsize="2" compact="compact"><dt>10</dt><dd>substratum</dd><dt>20</dt><dd>Diffusion barrier layer</dd><dt>30</dt><dd>first antireflection</dd><dt>40</dt><dd>Internal diffusion barrier layer, SnO₂-Layer</dd><dt>50</dt><dd>Under blocker</dd><dt>60</dt><dd>silver layer</dd><dt>70</dt><dd>upper blocker</dd><dt>80</dt><dd>Second antireflection</dd><dt>90</dt><dd>protective layer</dd></dl>