DE19541014A1 - Coating used on glass panes to protect e.g. paintings - Google Patents

Abstract

Coating comprises an optically active layer system (1) comprising at least two individual layers (6,8) each consisting of a nitride or a mixed nitride, where at least one of the nitride layers consists of a (mixed) metal nitride. Production of the coating is also claimed, in which the individual-layers are produced by cathode sputtering, especially reactive sputtering using a double magnetron operated by an average frequency current consumption.

Description

The invention relates to an optically acting Layer covering, consisting of one on substrates arranged multilayer system, the Layer system a high anti-reflective effect and has a high light transmission or a high he anti-reflective effect with a given light transmission sion.

Such anti-reflective layers are preferred on transparent in the visible light spectrum Substrates, in particular glass panes brings which z. B. for protection from paintings or for use in showcases or as a shop rear windows can be used.

A layer system is known from DE 41 17 257, which is placed on a transparent substrate  is brought up and a high anti-reflective effect points. This is based on DE 39 42 990 Layer system consists essentially of on the Substrate applied in alternating sequence layers of tall oxide and nitride. According to the DE 41 17 257 produced layer systems are sufficient high transmittance required today and the Demands for an inexpensive manufacturer no longer. Especially those there proposed layers consisting of TiO₂ can only be built in at high manufacturing costs according to expensive manufacturing process produ grace because the sputtering rate of TiO₂ at the there coating process used about 5 times is smaller than that for low refractive index SiO₂.

The object of the present invention is a Generic layer system and its manufacture specify the disadvantages avoids the layer systems mentioned at the beginning and the requirements that are required today look at the anti-reflective effect, the Kon increase in scan and increase in antistatic effect today's layers met.

At the same time, the requirements for this should be met created that only a small number of Single layers are needed.

This object is achieved by a Features of the main claim layer system fulfilled. A method of making egg  Nes layer system according to the invention is with the specified in claim 10 features.

A layer system according to the invention consists of several individual layers forming a coating, which are successively applied to a light-transparent substrate by means of a vacuum-assisted coating process, at least two individual layers consisting of a nitride or a mixed nitride and at least one of the nitride layers made of a metal nitride or a metal mixed nitride consists. Metal nitrides from the group consisting of titanium nitride (TiN) and / or zirconium nitride (ZrN) (see claim 2) are preferably provided for this purpose, which advantageously form both chemically and mechanically stable and hard layers. These metal nitride layers thus form an advantageous replacement for the high-refractive oxide layers previously used in classic antireflection filter layers. As substrate material is, as mentioned in claim 8, for. B. seen before glass that has a refractive index n _G of 1.46 n _G 1.6.

It is also contemplated that the very thin, he according to the invention as specified in claim 8, round 70 nm to 90 nm thick metal nitride layers each because embedded between two nitride layers are. This embedding ensures schender way that a destruction of a z. B. consisting of zirconium nitride or titanium nitride Layer by oxidation due to a direct on these layers deposited oxide layer avoided  becomes. This ensures high optical stability and quality of the overall layer system also about guaranteed for a long period.

Another advantage is that metal nitride layer layer systems a good antista tic effect, which is a significant reduction tion or prevention of electrostatic charging conditions such as this B. in television cathode ray tubes could otherwise occur.

As specified in subclaims 3 and 6, respectively summarizes an inventive layer system z. B. four or five individual layers, successively on egg nem substrate by means of cathode sputtering method according to claim 10 are applied. According to claim 7 it is provided that for improvement tion of the adhesive strength of the nitride layers an underlying oxide layer is the nitride layer on the oxide layer using an adhesion promoter layer is attached, which is preferably made of Nickel-chromium-nitride (NiCrN) exists and a Layer thickness of preferably 1 nm to 25 nm points.

To produce a layer system according to the invention by means of a sputtering method, it is provided that a double magnetron operated electrically with a medium-frequency power supply in the frequency range from 20 kHz to 70 kHz is used, which enables advantageous, cost-effective and qualitatively high-quality layer production. Typical process chamber pressures for layer production are in a pressure range from 1 × 10 ^-3 mbar to 8 × 10 ^-3 mbar. Depending on the type of layer to be applied, the process gas consists of an inert gas, preferably argon, and a reactive gas, preferably nitrogen or oxygen.

Another advantage of a herge according to the invention posed layer consists in the compared to conventionally produced layer systems low Total thickness of only approx. 100 nm. In comparison here classic anti-reflective coating systems Total thicknesses of approx. 240 nm to 350 nm layer thickness, which are only more expensive to manufacture len because the sputtering rate is of high refractive index Material like TiO₂ is very small compared to SiO₂. ZrN and TiN assign comparable rates TiO₂, however, is required according to the invention layer thickness very much with the same effect less; e.g. B. has a conventionally used one TiO₂ layer has a thickness of about 100 nm, where against a ZrN or TiN layer only one Has a thickness of 10 nm.

Further advantageous features of the invention are specified in the subclaims.

Below are particularly advantageous designs Rungsbeispiele described in the figures.

Show it:  

Fig. 1 shows a cross section of a four-A zelschichten existing applied on a substrate layer system,

Fig. 2 shows a cross section through a stem consisting of four monolayers Schichtsy,

Figure 3 is a cross-sectional view of an existing stems of five individual layers Schichtsy.,

Fig. 4 is a cross-sectional view of an existing stems of five individual layers Schichtsy,

Fig. 5 is a Transmissionsgrad- or reflection efficiency curve as a function of Lichtwel lenlänge for a ten four Einzelschich existing layer system according ei nem first embodiment,

Fig. 6 is a transmittance or reflectance curve depending on the einfal Lenden wavelength of a layer consisting of four individual layers system according to a second embodiment and example

Fig. 7 is a transmittance or reflectivity curve depending on the light wavelength of a layer system consisting of five individual layers.

The layer systems shown in Figs. 1 to 4 consist of four, as shown in Figs. 1 and 2, or five (see Fig. 3) or six (see Fig. 4) on a substrate 2 by means of a vacuum-assisted Coating method applied individual layers 4 , 6 , 8 , 10 , 12 , 14th

The layer system 1 of the first exemplary embodiment (see FIG. 1) is constructed as follows:

• - On the front 16 of the substrate 2 , a first, absorption-free layer 4 is applied, which consists of Si₃N₄ or AlN and has a layer thickness of 20 nm to 24 nm,
• the second optically active layer 6 consists of a 7 nm to 9 nm thick ZrN or TiN layer,
• - The third optically active layer 8 be consists of an absorption-free Si₃N₄ or AlN layer, which has a layer thickness of 1.5 nm to 2.5 nm,
• - The fourth optically active layer 10 be consists of an absorption-free layer made of SiO₂ or MgF₂ or Al₂O₃ and has a layer thickness of 60 nm to 100 nm.

The layer system of the second embodiment shown in FIG. 2 is constructed as follows:

• The first layer 12 applied directly on the front side 16 of the substrate 2 consists of TiO₂ or Ta₂O₅ and has a layer thickness of 20 nm to 24 nm.
• the second optically active layer 6 consists of ZrN or TiN and has a layer thickness of 7 nm to 9 nm,
• - The third optically active layer 8 be made of Si₃N₄ or AlN and has a layer thickness of 1.5 nm to 2.5 nm,
• - The fourth optically active layer 10 be made of SiO₂ or MgF₂ or Al₂O₃ and has a layer thickness of 60 nm to 100 nm.

The layer system of the third embodiment shown in FIG. 3 is constructed as follows:

• - The brought up directly on the substrate 2 first layer 12 consists of an absorption-free, consisting of TiO₂ or Ta₂O₅ be existing oxide layer with a layer thickness of 20 nm to 24 nm,
• - The second layer 4 applied to the first layer 12 consists of Si₃N₄ or AlN and has a layer thickness of 20 nm to 24 nm,
• the third optically active layer 6 consists of ZrN or TiN and has a layer thickness of 7 nm to 9 nm,
• - The fourth optically effective layer is egg ne absorption-free, from Si₃N₄ or AlN be standing nitride layer provided that a Layer thickness from 1.5 nm to 2.5 nm points out
• - As the fifth layer, an absorption-free layer consisting of SiO₂ or MgF₂ or Al₂O₃ be provided 10 , which has a layer thickness of 60 nm to 100 nm.

The layer system of the fourth exemplary embodiment shown in FIG. 4 has a total of six layers and is constructed as follows:

• - As the first layer 12 is an absorption-free oxide layer consisting of TiO₂ or Ta₂O₅, with a layer thickness of 20 nm to 24 nm, on which one
• - second, made of nickel-chromium nitride Adhesion layer is applied, wel surface thickness from 1 nm to 3 nm having,  
• - As a second optically active layer, egg ne ne absorption-free, Si₃N₄ or AlN be available nitride layer 4 is provided, which has a layer thickness of 20 nm to 24 nm, on which
• - A third optically effective and absorbing nitride layer 6 is applied, which consists of ZrN or TiN and has a layer thickness of 7 nm to 9 nm, on which
• - A fourth optically effective, absorption-free nitride layer 8 , consisting of Si₃N₄ or AlN, is applied in a layer thickness of 1.5 nm to 2.5 nm and from
• - A fifth optically active layer 10 , which is made of SiO₂ or MgF₂ or Al₂O₃ and has a layer thickness of 60 nm to 100 nm.

The substrate 2 in the aforementioned four exemplary embodiments consists of glass, in particular float glass, mineral glass or plexiglass, and has a refractive index n _G of 1.46 n _G 1.6, preferably of n _G = 1.52. The essential, optically effective properties of the parameters defined by the layer sequence and the respective layer thickness form the reflectance or transmittance depending on the incident light wavelength. The basic idea of the invention thus allows a large number of exemplary embodiments or layer systems, which are characterized in the three examples described below by the choice of the layer materials and layer thicknesses mentioned. Layer systems are presented in which the degree of reflection and the transmittance in the visible wavelength range of light have been measured.

The measurement results are shown graphically on the basis of curves in FIGS. 5, 6 and 7. In the description of the layer system on which FIG. 6 is based, the reference numerals of the description of FIG. 1 are used and in the description of the layer system shown in FIG. 7, the reference numbers of the description of FIG. 3 are used.

The layer system of the first example is like constructed as follows:

Substrate 2 : material glass, thickness: 2 mm;
Layer 4 : material Si₃N₄, layer thickness 22 nm;
Layer 6 : material ZrN, layer thickness 8 nm;
Layer 8 : material Si₃N₄, layer thickness 6 nm;
Layer 10 : material SiO₂, layer thickness 76 nm.

The layer 14 labeled in FIG. 4 is not present in this embodiment.

For this layer system, the reflection or Transmittance in percent over a wavelength gene range from 400 nm to about 700 nm specified.  

The measurement results for the Re Determine flexion and the transmission in Table 1 juxtaposed th wavelengths:

Table 1

The measurement results are shown graphically as curves in FIG. 5. The individual measuring points are connected to each other for guiding the eye. The wavelengths are entered in µm on the abscissa of the coordinate system in FIG. 5. The measured values for the reflectance are on the left ordinate of the curve diagram and the percentages for the transmittance are entered on the right ordinate of the coordinate system.

It can be seen from the course of the reflection curve Lich that in the core wavelength range of 420 nm  up to 680 nm the reflectance is far less than Is 0.5%. This desired high antire flex action corresponds to the course of the high values in the mentioned wavelength range Transmittance curve. So that points Layer system in the specified wavelength range ho he transmittance values between 80% and 90% on.

The layer system of the second example shown in FIG. 2 is constructed as follows:

Substrate 2 : material glass, thickness 2 mm;
Layer 12 : material TiO₂, layer thickness 12 nm;
Layer 6 : material ZrN, layer thickness 10 nm;
Layer 8 : material Si₃N₄, layer thickness 10 nm;
Layer 10 : material SiO₂, layer thickness 74 nm.

The reflection and transmission behavior of this layer system is plotted for the wavelength range from 400 nm to 688 nm in FIG. 6 as a function of the light wavelength. The reflection and transmission values on which FIG. 6 is based are compared in Table 2:

Table 2

From the light-wavelength-dependent behavior of the reflection curve shown in FIG. 6, it is clear that this has very low reflection values of less than 0.2% in the interval from 420 nm to 660 nm in the optically visible range. The reflectance is greater than 0.5% only for light wavelengths less than 400 nm or for light wavelengths greater than 700 nm. The transmission behavior of the last-mentioned layer system is determined by a high transmittance of over 90% at 400 nm and drops to higher wavelengths to approximately 75% at 688 nm essentially linearly.

The third exemplary layer system shown in FIG. 3 shows a light-wavelength-dependent transmission and reflection behavior similar to the second example. This latter layer system consists of the following layer structure:

Substrate 2 : material glass, thickness 2 mm;
Layer 12 : material TiO₂, layer thickness 10 nm;
Layer 6 : material Si₃O₄, layer thickness 2 nm;
Layer 6 : material ZrN, layer thickness 10 nm;
Layer 8 : material Si₃N₄, layer thickness 10 nm;
Layer 10 : material SiO₂, layer thickness 75 nm.

In comparison to the layer system described in the second example, this layer covering has a further layer consisting of Si₃N₄. The transmission and reflectivity of the layer system according to Example 3 is shown as a function of the light wavelength in Fig. 7. A comparison of the functional curves with those in FIG. 6 shows that the reflection and transmission behavior is similar to that of the layer system presented in Example 2. In the layer system according to Example 3, as desired, a very low degree of reflection and high transmittance is achieved over the optically visible light wavelength range. The reflection and transmission values on which FIG. 7 is based are listed in Table 3 below.

Table 3

The layer systems with which the transmission and reflection values mentioned in games 1 to 3 above were achieved were produced by the method described below. In a reactive gas atmosphere of approx. 5 × 10 ^-3 mbar, depending on the optical layer to be deposited, titanium, zirconium, silicon, aluminum, tantalum or nickel chrome was selected as the target material. Un using noble gas with the addition of a reactive gas such. B. an Ar / N gas mixture, was sputtered from the target surface under the action of sputtering target substance material, wel ches on the substrate 2 to be coated as a chemical compound, such as. B. ZrN or Si₃N₄, never strikes and forms as a closed single layer. Due to the temporal sequence of the sputtering process on different target materials, individual layers composed of different chemical elements are successively built up into individual layers to form a layer system which has the aforementioned optically acting properties.

On the coated side of the layer systems the surface resistance R  to R   5 kΩ / measured. The static charge of the  coated surfaces is by grounding them reduced or even completely canceled. In order to the desired antistatic effect is achieved.

Reference list

1 covering, layer system
2 substrate, glass
4 first layer
6 second layer
8 third layer
10 fourth layer, top layer
12 oxide layer
14 adhesion promoter layer
15 back
16 front

Claims (16)

1. covering consisting of an optically acting layer system for substrates, the layer system in particular having a high anti-flex effect and a high light transmission or having a high anti-reflective effect for a given light transmission, characterized in that the layer system ( 1 ) at least two, each made of a nitride or a mixed nitride consisting of individual layers ( 6 , 8 ), at least one of the nitride layers consisting of a metal nitride or a metal mixed nitride. 2. Rubber according to claim 1, characterized net that the existing of metal nitride cell layer consists of ZrN and / or TiN. 3. Covering according to claim 1 and / or 2, characterized in that the layer system ( 1 ) comprises at least four individual layers ( 4 , 6 , 8 , 10 , 12 ), wherein he ste, absorption-free on the substrate ( 2 ) Layer ( 4 , 12 ) is arranged, then a second, absorbing nitride layer ( 6 ), preferably ZrN or TiN, is arranged, then a third, absorption-free nitride layer ( 8 ), preferably consisting of SiN or AlN, is arranged is, then a fourth, from sorption-free layer ( 10 ) is arranged, which has a low refractive index and preferably consists of SiO₂ or MgF₂ or Al₂O₃ or their mixed oxides. 4. Covering according to at least one of claims 1 to 3, characterized in that the first, on the substrate ( 2 ) arranged layer ( 4 ) is a preferably made of Si₃N₄ or AlN de nitride layer ( 4 ). 5. Covering according to at least one of claims 1 to 3, characterized in that the first, arranged on the substrate ( 2 ) layer ( 12 ) is a preferably made of TiO₂ or Ta₂O₅ best existing oxide layer. 6. Covering according to claim 1 and / or 2, characterized in that the layer system ( 1 ) comprises at least five individual layers ( 4 , 6 , 8 , 10 , 12 ), wherein he ste, absorption-free on the substrate ( 2 ) Oxide layer ( 12 ), preferably consisting of TiO₂ or Ta₂O₅, is arranged, then a second, from sorption-free nitride layer ( 4 ), preferably consisting of Si₃N₄ or AlN, is arranged, followed by a third, absorbing de nitride layer ( 6 ), preferably consisting of ZrN or TiN, followed by a fourth, absorption-free nitride layer ( 8 ), preferably consisting of Si₃N₄ or AlN, followed by a fifth, absorption-free layer ( 10 ), which is a low one Has calculation coefficients and which vorzugwei se consists of SiO₂ or MgF₂ or Al₂O₃ or its mixed oxides. 7. Covering according to one of claims 1 to 6, characterized in that between the oxide layer ( 12 ) and the nitride layer ( 6 ) an adhesion promoter layer ( 14 ) is arranged, which preferably consists of nickel-chromium-nitride (NiCrN) and which has a layer thickness of preferably 1 nm to 2.5 nm. 8. covering, consisting of an optically acting, single-layer layer system for substrates, the layer system in particular having a high anti-reflective effect and high light transmission or having a high anti-reflective effect for a given light transmission, in particular according to at least one of claims 1 to 7 , characterized in that the substrate ( 2 ) consists of glass which has a refractive index n _G with 1.46 n _G 1.60, preferably with n _G = 1.52, and the first applied to the substrate ( 2 ) Layer ( 4 ) preferably consists of Si₃N₄ and has a layer thickness of 200 nm to 240 nm, that the second layer ( 6 ) preferably consists of ZrN and has a layer thickness of 70 nm to 90 nm, and that the third layer ( 8 ) preferably consists of Si₃N₄ and has a layer thickness of 1.5 nm to 2.5 nm and where the fourth layer ( 10 ) preferably consists of SiO₂ and a layer thickness of 70 nm to 80 nm. 9. Covering according to at least one of claims 1 to 8, characterized in that the Layer system (1) a sheet resistance R  from R   5 kΩ /. 10. A method for producing a covering according to at least one of claims 1 to 9, characterized in that the individual layers ( 4 , 6 , 8 , 10 , 12 ) by means of a cathode sputtering method, in particular by means of a reactive sputtering method using a medium frequency - Power supply operated double magnetrons are manufactured. 11. The method according to claim 10, characterized in that for coating glass ( 2 ), in particular float glass, by reactive sputtering of a silicon target using a layer of Si₃N₄ in the presence of a double magnetron electrically operated with a medium frequency generator a Sput tergasgemisches, which has argon gas and nitrogen gas, at a process chamber pressure p of 1 × 10 ^-3 mbar p 8 × 10 ^-3 mbar is deposited on the glass substrate ( 2 ). 12. The method according to claim 10 and / or 11, characterized in that by reactive sputtering of a silicon target with an electrically supplied by a medium frequency generator at a current frequency of 30 kHz to 60 kHz double magnetron a layer of SiO₂ in the presence of a sputter gas mixture comprising Ar and O₂, ge is formed, the process chamber pressure p being in a range of 1 × 10 ^-3 mbar p 8 × 10 ^-3 mbar. 13. The method according to any one of claims 9 to 12, characterized in that by reactive sputtering of an aluminum target using in particular a medium frequency generator electrically supplied Dop pelmagnetrons a layer of Al₂O₃ in the presence of a sputtering gas mixture, which Ar and O₂ comprises, at a process chamber pressure p of 1 × 10 ^-3 mbar p 8 × 10 ^-3 mbar is formed on the substrate ( 2 ). 14. The method according to at least one of the claims 9 to 12, characterized in that the Double magnetron at a current frequency of 30 kHz to 60 kHz is operated.   15. The method according to any one of claims 9 to 14, characterized in that the substrate ( 2 ) consists of glass, preferably of float glass. 16. The method according to at least one of claims 1 to 15, characterized in that a known coating method is used to apply the individual layers ( 4 , 6 , 8 , 10 , 12 ).