EP4018012A1

EP4018012A1 - Temperable coatings having diamond-like carbon and deposition by means of high-power impulse magnetron sputtering

Info

Publication number: EP4018012A1
Application number: EP20750282.4A
Authority: EP
Inventors: Jan Hagen; Viktor SCHEERMANN; Lorenzo MANCINI; Vincent Reymond
Original assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Current assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Priority date: 2019-08-21
Filing date: 2020-08-06
Publication date: 2022-06-29
Also published as: CO2022001806A2; BR112022001599A2; WO2021032493A1; MX2022002251A

Abstract

The invention relates to a method for producing a substrate having a coating comprising a layer of diamond-like carbon (DLC), the method comprising the application of the following layers to the substrate in this order: a) a layer of DLC, b) optionally a release layer composed of one or more plies, each ply being, independently, a metal ply or a nitride ply, and c) optionally an oxidation protection layer, the layer of DLC being deposited by magnetron PECVD by means of high-power impulse magnetron sputtering (HiPIMS).

Description

Temperable coatings with diamond-like carbon and deposition through

High performance pulsed magnetron sputtering

The invention relates to temperable diamond-like carbon coatings and a method for their production with the aid of high-power pulsed magnetron sputtering (HiPIMS).

A solution to improve the scratch resistance of a glass surface is urgently required, particularly for indoor applications. Diamond-like carbon (DLC) thin films are generally well suited for improving the scratch resistance of a surface, since they have a low coefficient of friction and a sufficiently high hardness.

Methods for producing DLC coatings are known. For example, WO 2004/071981 A1 describes a method for depositing DLC layers by means of ion beam technology. CN 104962914 A describes a vapor deposition device for the industrial production of DLC layers. CN 105441871 A relates to a device for physical vapor deposition and high-performance pulse magnetron sputtering for the production of thick DLC coatings. WO 2016/171627 A1 relates to the coating of a substrate, the coating comprising a carbon layer such as DLC, which can be applied by means of physical vapor deposition, e.g. by means of high-power pulse magnetron sputtering. Further methods and devices for DLC coating are mentioned, for example, in CN 20383434012 and JP 2011-068940.

WO 2019/020481 A1 describes a method for depositing DLC layers using a PECVD magnetron method.

A problem with DLC coatings is their temperature sensitivity. At high temperatures the DLC graphitizes (shift from sp ³ to sp ² coordination of the carbon atoms) and simply burns to CO2 at temperatures of> 400 ° C. Since glass hardening processes (tempering) require temperatures of up to 700 ° C, pure DLC coatings on glass simply disappear if they are not protected from oxidation.

One approach to providing temperable DLC coatings is based on Si doping of the DLC layer itself in order to improve the temperature resistance. Another approach, which is described, for example, in WO 2004/071981, US 7060322 B2, US 8443627 or US 8580336 B2, uses protective and release layers to prevent the DLC layer from burning off during tempering.

To protect the DLC coating during tempering, a coating concept is proposed in which the following layer sequence is applied to the substrate: substrate (e.g. glass) / base layer / DLC / release layer / anti-oxidation layer.

A substrate with such a coating can be tempered, the DLC layer being adequately protected. The release and anti-oxidation layers must, however, be quite thick (> 100 nm) in order to achieve adequate protection of the functional DLC layer. Removal of the release and protective layers after tempering is also very laborious and usually requires washing in acetic acid solution.

Different materials are proposed for the release and anti-oxidation layers. WO 2004/071981 A1 describes, for example, release layers based on substoichiometric ZnO. EP 2146937 describes anti-oxidation layers which contain aluminum nitride.

WO 2019/020485 A1 describes layer systems in which release layers containing Mg or Sn are used. The deposition takes place by means of plasma-assisted chemical vapor deposition (PECVD). However, a problem with the deposition of these layer systems using classic PECVD is that after tempering the glass substrate and removing the release and protective layers, a very cloudy appearance is often obtained, which is undesirable for indoor applications on glass. In addition, the mechanical resistance of the DLC worsens after tempering in comparison to the DLC after deposition and is not significantly better than with uncoated tempered float glass, as the Erichsen scratch tests (EST) and m-scratch tests show (Fig. 1a and Fig. 1 b).

US 2012/015196 A1 discloses a method for producing a coated substrate, wherein a glass substrate with at least one DLC layer and an overlying protective layer is subjected to a heat treatment. The protective layer can include a barrier layer that blocks oxygen. The protective layer can be removed again during or after the heat treatment. US 2018/051368 A1 describes an amorphous carbon film which comprises at least 95% carbon, the proportion of sp ³ -hybridized carbon being at least 30% and the hydrogen content being at most 5%. The carbon film is deposited using HiPIMS.

Methods for the deposition of DLC films have also been investigated in scientific studies. For example, Ganesan et. al. under the title "Synthesis of highly tetrahedral amorphous carbon by mixed-mode HiPIMS sputtering" (Journal of physics D: Applied Physics, Institute of Physics Publishing Ltd. GB, BD, 48, No. 44, October 9, 2015) a tetrahedral amorphous Carbon film with a proportion of sp ³ hybridized carbon of 80%, the film being deposited using HiPIMS. In "A review comparing cathodic arcs and high power impulse magnetron sputtering (HiPIMS)" by Andre Anders (Surface and coating technology, Vol. 257. September 2, 2014) an overview of HiPIMS technology is given. In both of the publications mentioned, depositions using HiPIMS are described, although no PECVD magnetron process is used.

The invention is based on the object of overcoming the above-described disadvantages in the prior art. The object is, in particular, to provide a method for producing a temperable coating system containing a DLC layer on a substrate, in which the DLC coating has no haze and maintains the good mechanical properties with regard to scratch resistance, in particular compared to uncoated tempered float glass

According to the invention, this object is achieved by a method according to claim 1. According to the further independent claim, the invention also relates to a coated substrate which can be obtained by the method according to the invention. Preferred refinements of the invention are given in the dependent claims.

The invention thus relates to a method for producing a substrate with a coating comprising a layer of diamond-like carbon (DLC), comprising the application of a layer of diamond-like carbon (DLC), the layer of diamond-like carbon (DLC) being produced by a plasma-enhanced chemical vapor deposition (PECVD) ) - Method with plasma generation via a magnetron target (magnetron PECVD) with at least one Carbon-containing reactant gas is deposited in a vacuum chamber by means of high-power pulsed magnetron sputtering (HiPIMS).

In the PECVD process, chemical deposition takes place from the gas phase, which is supported by the generation of a plasma. In a pure CVD process, the molecules of the reaction gas are split by the supply of heat, while this process is started by the accelerated electrons and ions of the plasma when using a plasma-assisted CVD (PECVD). In addition, ions are also generated in the plasma which, together with the radicals formed from the reaction gas and electrons of the plasma, result in the layer deposited on the substrate. The plasma is generated in the vacuum chamber in the presence of a reactant gas which according to the invention must contain at least carbon in order to obtain the desired layer of diamond-like carbon. The inventors have established that the decisive factor for the quality of the DLC layer obtained is the manner in which the plasma used to support the PECVD process was generated. The generation of a plasma in the PECVD method usually takes place, for example, by applying an alternating voltage or direct voltage between two electrodes or alternatively by inductive irradiation of an electromagnetic alternating field. Depending on the method used, the proportion of ionized molecules in the plasma can vary greatly, resulting in different product properties of the deposited layers. According to the invention, high-power pulse magnetron sputtering (HiPIMS) is used as the method for generating the plasma. With HiPIMS, a higher plasma density and thus a significantly higher ionization capacity of the sputtered target atoms can be achieved. When using HiPIMS to generate plasma, the inventors were able to determine an improved scratch resistance of the resulting DLC layer compared to DLC layers deposited by other methods, for example plasmas generated using bipolar or medium-frequency power supply. This improvement in the layer quality is accompanied by the higher degree of ionization achieved by HiPIMS.

Optionally, further layers can be applied to the DLC layer, the following layers being applied to the layer of diamond-like carbon (DLC) in this order: a release layer composed of one or more layers, each layer independently of one another being a metallic or nitridic layer, and

- an anti-oxidation layer.

Surprisingly, it was found that the use of this DLC deposition process gives DLC coatings of excellent mechanical quality (high scratch resistance). If heat treatment of the substrate is desired, at least one release layer and at least one oxidation protection layer are applied to the surface of the DLC layer facing away from the substrate. The release layer and the anti-oxidation layer can easily be removed by dipping in water and gently wiping or brushing. In addition, the DLC coatings showed good optical quality (no haze) after the heat treatment. With regard to the high optical quality, it is particularly noteworthy that this high optical quality can also be achieved for known layer structures, such as those described in WO 2019/020485, using HiPIMS as the DLC deposition method according to the invention, and cloudiness is avoided. The method can be implemented for existing magnetron deposition machines using high power pulse magnetron sputtering.

The invention is explained below and with reference to the attached figures. In this shows:

Fig. 1a photos of Erichsen Scratch Test (EST) traces, (0-10 N), for a DLC layer, produced by PECVD magnetron process using a bipolar power supply and a release layer containing tin according to Example 2 of WO 2019/020485 A1, left : DLC layer as deposited (wa), right: after heat treatment at 650 ° C and subsequent separation of the release layer and the anti-oxidation layer

1b shows a diagram of the coefficients of friction for a DLC layer produced by the PECVD magnetron process using a bipolar power supply and a release layer containing tin according to Example 2 of WO 2019/020485 A1, PLC (650 ° C.): uncoated tempered float glass from Saint-Gobain "Planiclear" (PLC), PECVD (wa): DLC layer as deposited; PECVD (650 ° C): DLC layer after heat treatment at 650 ° C and subsequent separation of the release layer and the anti-oxidation layer Fig. 2a is a photo of the Erichsen Scratch Test (EST) traces (0 - 10 N) for an uncoated tempered float glass from Saint-Gobain "Planiclear" (PLC 650 ° C)

2b is a photo of the Erichsen Scratch Test (EST) traces (0-10 N) for a DLC layer produced according to an example according to the invention after heat treatment at 650 ° C and subsequent separation of the release layer and anti-oxidation layer (tempered HiPIMS DLC)

3 shows a Raman spectrum of the DLC layer produced according to example 2 of WO 2019/020485 A1.

4 shows a Raman spectrum of the DLC layer produced according to inventive example 1 in Table 1 after heat treatment at 650 ° C. and subsequent separation of the release layer and the anti-oxidation layer.

5 shows a diagram of the dependence of the graphitization temperature on the proportion of sp ³ -C in DLC

In the method according to the invention, a substrate is provided with a coating which comprises a DLC layer. The substrate can be any substrate. The substrate is preferably made of ceramic, plastic, glass ceramic or glass, a glass substrate being particularly preferred, in particular a glass pane. Examples of glass are soda-lime glass, float glass, borosilicate glass or aluminosilicate glass. Substrates made of plastic can in particular be used if no heat treatment (tempering) is provided in the process. Examples of plastic substrates are substrates made of polymethyl methacrylate (PMMA) or polycarbonate (PC). The thickness of the substrate, in particular the glass substrate, can for example be in the range from 0.1 to 20 mm.

The method according to the invention preferably comprises the application of the following layers to the substrate in this order: a. a layer of DLC, b. a single or multilayer release layer and c. an anti-oxidation layer. Of the three layers, the DLC layer is therefore closest to the substrate. The release layer is arranged over the DLC layer and the oxidation layer is arranged over the release layer. The layer sequence with increasing distance to the substrate is thus: DLC layer, release layer, oxidation layer. In this preferred embodiment of the method according to the invention, after the deposition DLC layer, a release layer and an oxidation layer are applied as additional layers. These additional layers make the heat treatment of the substrate with DLC layer possible. If no heat treatment is desired, the release layer and the oxidation layer can be dispensed with. The following information relates to the coated substrate before a heat treatment, unless expressly stated otherwise.

Layers of diamond-like carbon are well known. As usual, diamond-like carbon is abbreviated as DLC ("diamond-like carbon"). The layers of DLC are also referred to as DLC layers. In DLC layers, hydrogen-free or hydrogen-containing amorphous carbon is the predominant component, and the carbon can consist of a mixture of sp ³ and sp ² -hybridized carbon; if necessary, sp ³ -hybridized carbon or sp ² -hybridized carbon can predominate. Examples of DLC are those with the designation ta-C and a: CH. The DLC layer can be doped or undoped. Doping elements are, for example, silicon, metals, oxygen, nitrogen or fluorine.

The DLC layer is deposited by a PECVD process with plasma generation via a magnetron target (magnetron PECVD) with at least one carbon-containing reactant gas in a vacuum chamber by means of high-power pulse magnetron sputtering (HiPIMS). PECVD stands for plasma-enhanced chemical vapor deposition. The plasma is generated using a magnetron target (magnetron PECVD).

The magnetron PECVD method is a PECVD method in which the plasma is generated by a magnetron or a magnetron target. The substrate, which is optionally precoated with one or more ion diffusion barrier layers, is coated in a vacuum chamber in which a magnetron provided with the target and the substrate are arranged and the plasma generated by the magnetron target is formed. At least one carbon-containing reactant gas is introduced into the vacuum chamber under vacuum, whereby fragments of the reactant gas are formed which are deposited on the substrate with the formation of the DLC layer. In addition to the at least one carbon-containing reactant gas, further reactant gases can be present which optionally contain carbon. The carbon-containing reactant gas can, for example, be one or more hydrocarbons, in particular alkanes and alkynes, such as, for example, C ₂ H ₂ or CH ₄ , or organosilicon compounds, for example tetramethylsilane. If necessary, inert gases such as argon can also be introduced into the vacuum chamber to support the plasma. The magnetron target can, for example, be made of silicon, which is optionally doped with one or more elements, such as Al and / or boron, or titanium or carbon.

An essential feature of the method according to the invention is the use of magnetron PECVD by means of high-power pulse magnetron sputtering, here abbreviated as HiPIMS as usual. HiPIMS is a magnetron sputtering technique known to those skilled in the art with a pulse-modulated power supply for the magnetron target. With HiPIMS, high-power pulses of up to a few hundreds of microseconds are applied to the magnetron target at frequencies in the range from a few Hz to several kHz.

The deposition of DLC using HiPIMS requires a special pulse-modulated power supply that offers a variety of options for influencing the plasma (pulse length, frequency, maximum voltage and current). The HiPIMS parameters and also other parameters such as deposition pressure and the ratio of inert gas, such as Ar, to reactant gas, such as hydrocarbons, e.g. C2H2, can be varied to optimize the quality of the deposited DLC layers and their sp ³ / sp ² content.

An inert gas is also preferably added. In this case, the ratio of inert gas, such as Ar, to carbon-containing reactant gas, such as hydrocarbons, for example C2H2, in the vacuum chamber is, for example, in the range from 1:10 to 20:10, preferably from 2:10 to 10:10, based on the reactive gas flow, measured in sccm.

The process parameters can be scaled to larger coating systems such as coating systems for coating jumbo glass panes in the format approx. 3x6 m ^2. Apart from the use of special HiPIMS power supplies, the method according to the invention is compatible with the existing coating systems.

The HiPIMS is preferably operated with a pulse in the range from 50 to 250 me, more preferably from 100 to 200 me. The frequency used in the HiPIMS is preferably in the range from 300 to 2000 Hz, more preferably from 500 to 1500 Hz. These parameters have proven to be particularly advantageous for good mechanical properties (in particular a high scratch resistance) of the DLC layers and a high sp ³ proportion.

In the investigations carried out it was found that the following HiPIMS process conditions with regard to deposition pressure and peak current are particularly favorable in order to achieve good mechanical properties of the DLC layers obtained:

Low deposition pressure, preferably <4 pbar, more preferably -2 pbar. The layer made of DLC is therefore deposited in the vacuum chamber preferably at a pressure of less than 4 mbar, more preferably less than 3 mbar, even more preferably less than 2.5 mbar. The pressure is expediently more than 1 mbar, preferably more than 1.5 mbar. The pressure data in this application relate to absolute values.

Low peak current, preferably <500 A, better -150 A. The HiPIMS is therefore preferably operated with a peak current of 500 A to 50 A, more preferably 300 to 60 A, even more preferably 200 to 100 A. The mentioned peak current relates to a length of the magnetron target of approx. 1 m and scales linearly with its length.

When setting the peak current, make sure that it scales with the length of the target used. The HiPIMS is therefore preferably operated with a peak current in the range from 500 to 50 A per 1 m magnetron target length, more preferably 300 to 60 A per 1 m magnetron target length, even more preferably 200 to 100 A per 1 m magnetron target length. In order to enable a comparison of the parameters used, a normalization can be carried out on the total surface of the target. With a typical target diameter for a rotary target of 15 cm, for example, a total target area of 4712 cm ² per meter of target length results. This results in a peak ^{current density of 0.1 A / cm 2} to 0.01 A / cm ² with the peak currents mentioned in the range of 500 to 50 A per 1 m of magnetron target length. For the preferred peak currents mentioned, preferred peak ^{current densities of 0.06 A / cm 2} to 0.012 A / cm ² , particularly preferably 0.04 A / cm ² to 0.02 A / cm ² per meter of target length result. In practice, it should be noted that the effective area of the target on which the plasma ignites is significantly less than the total target area. Thus, in practice, significantly higher peak current densities are to be expected. It is further preferred that the HiPIMS is operated at a cathode power of 1 to 15 kW per 1 m magnetron target length, preferably 5 to 10 kW per 1 m magnetron target length. The cathode outputs can also be normalized to the total target surface, with output densities of 0.2 W / cm ² to 3.2 W / cm ² , preferably 1.06 W / cm ² to 2.12 W / cm ² per meter of target length being achieved . In practice, this results in a higher power density due to the effective area of the target, which differs from the total target area.

The peak currents, peak current densities, powers and power densities mentioned are advantageously low, so that the risk of target damage due to excessive current densities and power densities is avoided.

The method according to the invention further comprises the application of a release layer composed of one or more layers, each layer independently of one another being a metallic or a nitridic layer. The release layer is applied to a substrate which has a coating which comprises or consists of the DLC layer and optionally and preferably at least ion diffusion barrier layers between the substrate and the layer of DLC.

In a preferred embodiment, the metallic layers and / or the nitridic layers contain at least one metal selected from tin and magnesium or alloys thereof, or at least one transition metal selected from Mo, W, Ta, Nb, Ti, Zr, Hf, Ni and Cr or an alloy thereof, more preferably a combination of Ni and Cr. In the case of two or more transition metals and two or more layers, the transition metals can, for example, be present jointly or separately in different layers in each layer, or a combination thereof, as is understood by the person skilled in the art.

In one embodiment, the release layer is formed from one or more metallic layers, preferably from one metallic layer. The metallic layer or layers preferably contain at least one metal selected from tin and magnesium or alloys thereof, or at least one transition metal selected from Mo, W, Ta, Nb, Ti, Zr, Hf, Ni and Cr or an alloy of tin or Magnesium or two or more of these transition metals mentioned, more preferably a combination of nickel and chromium, or are formed therefrom. A nickel-chromium alloy is particularly preferred. The release layer preferably contains at least 80 atomic %, more preferably at least 90 atom%, particularly preferably at least 95 atom%, of the transition metal or metals mentioned, preferably of Ni and Cr.

In a preferred embodiment, the release layer is formed from one or more metallic layers which contain or consist of nickel and chromium. In the case of several layers, nickel and chromium can be present together in each layer or separately in different layers or in a combination thereof. It is preferred that the proportion of nickel in the release layer is in the range from 60 atom% to 95 atom%, preferably from 70 atom% to 90 atom%, and the proportion of chromium in the release layer is in the range from 5 atom% to 40 atom%, preferably from 10 atom% to 30 atom%. A nickel-chromium alloy made of 80 Ni / 20 Cr is particularly suitable.

In a further preferred embodiment, the release layer is formed from one or more metallic layers which contain or consist of tin or magnesium or an alloy of one of these metals. Tin and magnesium are beneficial from a health and environmental perspective.

In one embodiment, the release layer is formed from one or more nitridic layers, preferably from one nitridic layer. The nitridic layer or layers preferably contain at least one transition metal selected from Mo, W, Ta, Nb, Ti, Zr, Hf, Ni and Cr or an alloy of two or more of these transition metals, the or at least one of the transition metals being a nitride forms, more preferably a combination of nickel and chromium, with nickel and / or chromium forming a nitride, or are formed therefrom. In the case of several layers, nickel and chromium can be present together in each layer or separately in different layers or in a combination thereof.

The nitride of the transition metal or metals, such as the nitride of nickel and / or chromium, can be present as stoichiometric or substoichiometric nitride.

In a preferred embodiment, the release layer is formed from one or more nitridic layers which contain nickel and chromium, with nickel and / or chromium forming a nitride or consisting thereof.

In a further embodiment, the release layer is formed from one or more metallic layers and one or more nitridic layers. The metallic and nitridic layers are each as described above with regard to this the release layer containing only metallic or nitridic layers, also with regard to the preferred embodiments. In the preferred embodiment, the release layer contains nickel and chromium, with nickel and / or chromium forming or consisting of a nitride in the nitridic layer (s).

The release layer is most preferably composed of one or more metallic layers that contain or consist of Ni and Cr, or of one or more nitridic layers that contain Ni and Cr, with Ni and / or Cr being present as nitrides, or consist thereof, or of one or more metallic layers and one or more nitridic layers that contain Ni and Cr, with Ni and / or Cr forming a nitride in the nitridic layer or layers, since with these materials the release layer could most easily be washed away and after heat treatment and removal of the release layer and anti-oxidation layer, the best optical properties (no blister-related haze) were observed on the substrates coated with DLC.

The release layer comprising one or more layers can be deposited on the substrate provided with the DLC layer by means of well known methods or vapor deposition methods, preferably by sputtering, e.g. magnetron sputtering, co-sputtering or ion beam evaporation.

After a heat treatment or tempering of the coated substrate, the release layer enables the oxidation protection layer together with the release layer to be easily detached by a simple washing process, as explained below.

The method according to the invention further comprises the application of an anti-oxidation layer to the substrate provided with the release layer. The oxidation protection layer protects the DLC layer, in particular from the oxygen in the environment. The oxidation protection layer makes it possible to subject the substrate with the DLC layer located thereon to a heat treatment or to tempering, without the DLC layer being partially or completely degraded. Such anti-oxidation layers and their formation are well known in the art and they can, for example, contain or consist of a material selected from silicon carbide, silicon nitride, silicon oxynitride, metal nitride, metal carbide, in each case in undoped or doped form, or a combination thereof. Alternatively, anti-oxidation layers comprising aluminum are also suitable for use in the method according to the invention. In the method according to the invention, an oxidation protection layer is preferably applied which contains or consists of silicon nitride or doped silicon nitride, in particular S1 ₃ N ₄ or doped S1 ₃ N ₄ , silicon nitride doped with Zr, Ti, Hf and / or B being particularly preferred and with boron doped silicon nitride is most preferred. The proportion of B as a doping element can be, for example, in the range from 0.1 to 100 ppm.

The combination of the above-explained release layer with an oxidation protection layer containing silicon nitride or doped silicon nitride enables particularly good protection of the DLC layer, in particular when silicon nitride doped with boron is used for the oxidation protection layer. This is advantageous because in this way a relatively thin anti-oxidation layer, e.g. with a thickness of no more than 100 nm or even significantly less, offers sufficient protection. This reduces the production costs and is also advantageous with regard to a simplified detachment of the layers after the heat treatment.

The proportion of silicon nitride or doped silicon nitride, in particular boron-doped silicon nitride, in the oxidation protection layer is preferably at least 90% by weight, preferably at least 95% by weight, more preferably at least 98% by weight, of the oxidation protection layer.

The usual methods or gas phase deposition methods can be used to apply the oxidation protection layer, e.g. PVD, in particular sputtering, preferably magnetron sputtering, CVD and atomic layer deposition (ALD).

The layer made of DLC preferably has a layer thickness of 1 to 20 nm, more preferably 2 to 10 nm, particularly preferably 3 to 8 nm. These layer thicknesses are particularly advantageous in order to achieve a good visual appearance and high transparency. The layer thickness range from 3 nm to 8 nm offers an optimal compromise between mechanical resistance and the highest possible transparency. The release layer preferably has a layer thickness of 1 to 15 nm, more preferably 2 to 10 nm, particularly preferably 3 to 10 nm. The oxidation protection layer preferably has a layer thickness of 10 to 100 nm, preferably 20 to 75 nm.

In an optional and preferred embodiment, the method according to the invention further comprises the application of one or more ion diffusion barrier layers between the substrate and the DLC layer. The ion diffusion barrier layer prevents, in particular, an undesired migration of ions, in particular sodium ions, from the substrate into the coating and the degradation of the DLC, in particular during the heat treatment.

Such ion diffusion barriers and their formation are well known in the art. The usual materials can be used for this. The usual methods or gas phase deposition methods can be used to apply ion diffusion barrier layers, e.g. PVD, in particular sputtering, preferably magnetron sputtering, CVD or ALD.

The ion diffusion barrier layer contains, for example, a material selected from silicon carbide, silicon oxide, silicon nitride, silicon oxynitride, metal oxide, metal nitride, metal carbide, in each case in doped or undoped form, or a combination thereof or consists essentially thereof. The ion diffusion barrier layer preferably contains or consists of a material selected from silicon nitride, silicon oxynitride, doped silicon nitride or doped silicon oxynitride.

In a more preferred embodiment, the ion diffusion barrier layer contains silicon nitride, in particular S1 ₃ N ₄ , or doped silicon nitride, for example silicon nitride doped with Al, Zr, Ti, Hf and / or B, silicon nitride doped with aluminum nitride or aluminum being particularly preferred.

The one or more ion diffusion barrier layers preferably contain the material mentioned, in particular silicon nitride or doped silicon nitride, e.g. silicon nitride doped with aluminum nitride or aluminum, in a proportion of at least 90% by weight, preferably at least 95% by weight, more preferably at least 98% by weight. -%. The one or more ion diffusion barrier layers have, for example, a layer thickness of 1 to 50 nm, preferably 5 to 30 nm.

More complex layer systems, such as, for example, so-called low-E layer systems, also act as ion diffusion barrier layers in the context of the invention. In principle, any layer systems can assume the function of an ion diffusion barrier layer, provided that there is only a corresponding barrier effect.

In a preferred embodiment, the method according to the invention comprises the further processing of the coated substrate produced, comprising the DLC layer, the release layer, the anti-oxidation layer and optionally the one or more ion diffusion barrier layers applied between substrate and DLC layer, comprising: a. Heat treatment of the substrate with the coating, comprising the DLC layer, the release layer, the oxidation protection layer and, if appropriate, the one or more ion diffusion barrier layers applied between the substrate and the DLC layer, and b. Removal of the anti-oxidation layer and the release layer from the heat-treated, coated substrate by a washing process.

The heat treatment can also be an annealing. The heat treatment, for example for a glass substrate, can be carried out at a temperature of 300 to 800 ° C, preferably 500 to 700 ° C, more preferably 600 to 700 ° C, for example. The duration of the heat treatment or tempering varies depending on the treated system and the temperature used, but can be, for example, 1 to 10 minutes.

For the washing process, water, acids, alkalis and organic solvents, for example, can be used as washing medium, with water being preferred. The washing process can be carried out, for example, by rinsing with the washing medium, by washing with the action of brushes or fleeces, or preferably by dipping into the washing medium. The washing process can be carried out at ambient temperature (e.g. in the range of 15 to 30 ° C). The washing medium can optionally also be heated. The anti-oxidation layer and the release layer can usually be easily removed by simply immersing them in a water bath.

The invention also relates to the coated substrate which can be obtained by the method according to the invention. This can be the coated substrate, which comprises the following layers in this order on the substrate: the DLC layer, the release layer, the anti-oxidation layer and optionally the one or more ion diffusion barrier layers applied between the substrate and the DLC layer. The coated substrate can also be the coated substrate, comprising the DLC layer and optionally the one or more ion diffusion barrier layers applied between the substrate and the DLC layer. This is obtained after heat treatment of the substrate with the coating, comprising the DLC layer, the release layer, the oxidation protection layer and optionally the one or more ion diffusion barrier layers applied between the substrate and the DLC layer, and after subsequent removal of the anti-oxidation layer and the release layer from the heat-treated, coated substrate by the washing process.

The coated substrate which can be obtained by the method according to the invention comprises a DLC layer whose carbon is a mixture of sp ³ - and sp ² - hybridized carbon and a proportion of at least 40%, preferably at least 50%, sp ³ -hybridized Has carbon. A proportion of at least 60% is particularly preferred. This is advantageous with regard to a high graphitization temperature and the resulting high temperature resistance of the coating.

In the following, the invention is explained in greater detail on the basis of non-limiting exemplary embodiments with reference to the accompanying drawings.

Examples

Examples 1 to 3 The following layers were applied to glass substrates in this order:

1) Ion diffusion barrier layer made of silicon nitride doped with aluminum nitride (S N ^ AI) with a thickness of 20 nm, deposition method: medium-frequency magnetron sputtering.

2) Layer of diamond-like carbon (DLC) with a thickness of 5.0 nm, deposition method: magnetron PECVD (target: silicon doped with aluminum) in

Vacuum chamber using HiPIMS, pulse 150 me

3) Release layer made of a metallic layer made of Ni-Cr alloy (NiCr, atomic ratio Ni / Cr: 80/20) with a thickness of 5 nm, deposition process: direct current magnetron sputtering 4) Anti-oxidation layer made of boron-doped silicon nitride (SN ^ B) with a

Thickness of 50 nm, deposition method: medium frequency magnetron sputtering

3 samples were produced, the process and deposition parameters each being set as indicated in Table 1. Rate is the deposition rate, max is maximum, I is current (max of I is the peak current), U is voltage, f is frequency, Ar is used as an inert gas, C2H2 and N2 are reactant gases (N2 for the production of silicon nitrides for ion diffusion barrier layer and anti-oxidation layer). Current, voltage, frequency relate to the parameters of the pulse-modulated power supply of the magnetron target. Table 1

The anti-oxidation layer and release layer can usually be easily removed after heat treatment by simply immersing them in a water bath. Erichsen scratch test (EST)

The Erichsen scratch test is a device with a turntable on which the sample is fixed and a variable load is applied via a metal tip. By turning the plate, an annular scratch is created.

The mechanical scratch resistance of the DLC coating obtained according to Example 1 according to the invention after heat treatment at 650 ° C. and subsequent separation of the release layer and anti-oxidation layer in the Erichsen scratch test, traces (0-10 N) is shown in Fig. 2b, which is a photo of the DLC coating sample after the test shows.

Figure 2a is a photograph of uncoated float glass (Planiclear (PLC) from Saint-Gobain after annealing which has been subjected to EST.

1 a shows photos of the EST, tracks (0-10 N), for a DLC layer that was produced by the PECVD magnetron process using a bipolar power supply and a release layer containing tin according to Example 2 of WO 2019/020485 A1, left : DLC layer as deposited (wa), right: after heat treatment at 650 ° C and subsequent separation of the release layer and the anti-oxidation layer.

The improvement in terms of low cloudiness and good mechanical resistance of the DLC layer produced according to the invention (FIG. 2b) compared with the DLC layer produced with a bipolar power supply according to FIG. 1a can be clearly seen.

The turbidity can be clearly seen in FIG. 1 a on the right. It is the bright wreath of light that is created by the clouding (scattering). There is no such wreath of light in the other figures.

The circular EST scratch at 10 N can hardly be seen on the tempered DLC layer according to the invention (FIG. 2b), while it is clearly visible on the uncoated float glass (FIG. 2a). Compared to Fig. 1a, right photo, you can see a drastic improvement, since compared to Fig. 2b in Fig. 1a, almost all scratch marks are visible.

Raman Spectroscopy Analysis

3 shows a Raman spectrum of the DLC layer produced according to Example 2 of WO 2019/020485 A1. 4 shows a Raman spectrum of the DLC layer produced according to example 1 according to the invention after heat treatment at 650 ° C. and subsequent separation of the release layer and the anti-oxidation layer.

A comparison of FIGS. 3 and 4 shows a clear difference. A Raman spectroscopy analysis (Gauss fit) of the spectra shows that HiPIMS deposition according to the present invention (FIG. 4) results in a higher degree of sp ³ coordination than with the DLC layer not according to the invention according to FIG. 3. The proportion of sp ³ -hybridized carbon can be seen in the present Raman spectra from the ratio of the two peaks occurring within a spectrum to one another. ^{The higher sp 3} fraction that can be determined in the spectrum in FIG. 4 leads to a higher temperature stability and to reduced graphitization of the DLC. The relationship between the degree of sp ³ coordination and temperature stability is known from the literature. 5 shows a diagram of the dependence of the graphitization temperature on the proportion of sp ³ -C in DLC. The relationship shown in Figure 5 was for example in the publication "60 years of DLC coatings: Historical highlights and technical review of cathodic arc processes to synthesize various DLC types, and their evolution for industrial applications, Surf. Coat. Tech. 257, 213-240, 2014 ”.

The deposition of DLC in a PECVD magnetron process with a bipolar power supply did not show a sufficiently high sp ³ content and the DLC layers obtained were therefore susceptible to DLC graphitization during temperature control. According to the invention, this disadvantage can be overcome by DLC deposition with the aid of HiPIMS power supply.

Comparative example 1

An ion diffusion barrier layer, DLC layer, release layer and anti-oxidation layer were applied to a glass substrate in the same way as in Examples 1 to 3, the process and deposition parameters being set as indicated in Table 2 d is the layer thickness.

In contrast to Examples 1 to 3 according to the invention, the DLC layer was not applied by a magnetron PECVD with HiPIMS power supply, but rather by a magnetron PECVD with a bipolar power supply. Table 2

Examples 4 to 7 The deposition of DLC by means of HiPIMS enables a multitude of possibilities for influencing the plasma (pulse length, frequency, maximum voltage and current) due to the special power supply. A suitable setting of these HiPIMS parameters and also other parameters such as deposition pressure and the ratio of inert gas such as Ar to reactant gas such as hydrocarbon can be used to optimize the quality of the deposited DLC layers and the sp ³ / sp ² ratio.

The influence of HiPIMS parameters on the properties of the DLC coatings obtained was examined. Table 3 shows the respective parameters used in the examples. For this purpose, ion diffusion barrier layer, DLC layer, release layer and anti-oxidation layer were applied to four glass substrates in the same way as in Examples 1 to 3, unless the process and deposition parameters were set as indicated in Table 3. Table 3 The DLC layers produced according to Examples 4 to 7 according to the invention after heat treatment at 650 ° C. and subsequent separation of the release layer and the anti-oxidation layer were examined for their scratch resistance by the Erichsen scratch test. The results are shown in Table 4. The quality of the scratch resistance is best with "1 + 5", then "2 + 5", then "3 + 7" and finally "4 + 8" with the lowest scratch resistance.

Table 4.

The data show that the following settings are particularly favorable in order to achieve good mechanical properties of the DLC layers obtained:

Low deposition pressure, preferably <4 pbar, more preferably ~ 2 pbar. The layer made of DLC is therefore deposited in the vacuum chamber preferably at a pressure of less than 4 mbar, more preferably less than 3 mbar, even more preferably less than 2.5 mbar. The pressure is expediently more than 1 mbar, preferably more than 1.5 mbar.

Low peak current, preferably <500 A, better -150 A, based on a magnetron target length of 1 m. The HiPIMS is therefore preferred with a peak current per m magnetron target length of 500 A to 50 A, more preferably 300 to 60 A, even more preferably 200 to 100 A, operated.

Claims

1. A method for producing a substrate with a coating comprising a layer of diamond-like carbon (DLC), comprising applying the following layers to the substrate in this order: a. a layer of diamond-like carbon (DLC), b. optionally a release layer composed of one or more layers, each layer independently of one another being a metallic or a nitridic layer, and c. optionally an anti-oxidation layer, the layer of diamond-like carbon (DLC) being deposited by a plasma-assisted chemical vapor deposition (PECVD) process, the supporting plasma in a vacuum chamber via a magnetron target (magnetron PECVD) in the presence of at least one reactant gas containing at least one carbon

High-power pulsed magnetron sputtering (HiPIMS) is generated.

2. The method of claim 1, further comprising:

Application of a release layer of one or more layers, each layer independently of one another being a metallic or a nitridic layer, on the DLC layer

Application of an anti-oxidation layer on the release layer, heat treatment of the substrate with the coating comprising the layer of DLC, the release layer and the anti-oxidation layer, preferably at a temperature of 300 to 800 ° C, and

Removal of the anti-oxidation layer and the release layer from the heat-treated, coated substrate by a washing process.

3. The method according to claim 1 or 2, further comprising applying one or more ion diffusion barrier layers between the substrate and the layer of DLC, wherein the one or more ion diffusion barrier layers preferably contain or consist of silicon nitride, silicon oxynitride, doped silicon nitride or doped silicon oxynitride, with Al, Zr, Ti, Hf and / or B doped silicon nitride and in particular silicon nitride doped with aluminum nitride or aluminum is particularly preferred.

4. The method according to any one of claims 1 to 3, wherein the metallic layer or layers of at least magnesium or tin or at least one transition metal selected from Mo, W, Ta, Nb, Ti, Zr, Hf, Ni and Cr or an alloy of two or more of these metals, preferably nickel and chromium, contain or are formed therefrom and / or the nitridic layer or layers at least one transition metal selected from Mo, W, Ta, Nb, Ti, Zr, Hf, Ni and Cr or a Alloy of two or more of these transition metals, preferably Ni and Cr, wherein the or at least one of the transition metals forms, contains or is formed from a nitride.

5. The method according to any one of claims 1 to 4, wherein the release layer is formed from one or more metallic layers which contain or consist of nickel and chromium, the proportion of nickel in the release layer preferably in the range from 60 atom% to 95 Atom%, preferably from 70 atom% to 90 atom%, and the proportion of chromium in the release layer is preferably in the range from 5 atom% to 40 atom%, preferably from 10 atom% to 30 atom% %, or where the release layer is formed from one or more nitridic layers containing nickel and chromium, with nickel and / or chromium forming a nitride, or consisting of it, or where the release layer consists of one or more metallic layers and one or a plurality of nitridic layers is formed, the release layer containing nickel and chromium, with nickel and / or chromium forming a nitride in or consisting of the nitridic layer or layers.

6. The method according to any one of claims 1 to 5, wherein the anti-oxidation layer contains or consists of silicon nitride or doped silicon nitride, in particular S1 ₃ N ₄ _{or S1 3} N ₄ doped with Zr, Hf, Ti and / or B, with boron doped silicon nitride is preferred.

7. The method according to any one of claims 1 to 6, wherein the layer of DLC has a layer thickness of 1 to 20 nm, preferably from 2 to 10 nm, particularly preferably from 3 to 8 nm, and / or the release layer has a layer thickness of 1 to 15 nm, preferably from 2 to 10 nm, particularly preferably from 3 to 10 nm, and / or the anti-oxidation layer has a layer thickness of 10 to 100 nm, preferably 20 to 75 nm.

8. The method according to any one of claims 1 to 7, wherein the substrate is ceramic, glass ceramic or glass, glass, in particular float glass, being preferred.

9. The method according to any one of claims 1 to 8, wherein the layer of DLC at a

Pressure of less than 4 mbar, preferably less than 3 mbar, more preferably less than 2.5 mbar, is deposited in the vacuum chamber.

10. The method according to any one of claims 1 to 9, wherein the HiPIMS has a peak ^{current density of 0.1 A / cm 2} to 0.01 A / cm ² per 1 m magnetron target length, preferably 0.06 A / cm ² to 0.012 A / cm ² per 1 m magnetron target length, particularly preferably 0.04 A / cm ² to 0.02 A / cm ² per 1 m magnetron target length.

11. The method according to any one of claims 1 to 10, wherein the HiPIMS is operated with a pulse in the range from 50 to 250 me, preferably from 100 to 200 me, and / or a frequency from 300 to 2000 Hz, preferably from 500 to 1500 Hz becomes.

12. The method according to any one of claims 1 to 11, wherein the HiPIMS with a

Peak power density from 0.2 W / cm ² to 3.2 W / cm ² per 1 m of magnetron

Target length, preferably 1.06 W / cm ² to 2.12 W / cm ² per 1 m magnetron target length, is operated.

13. The method according to any one of claims 1 to 12, wherein the release layer, the oxidation protection layer and, if used, the at least one ion diffusion barrier layer are applied by gas phase deposition processes, the release layer preferably being applied by sputtering, co-sputtering or ion beam evaporation.

14. Coated substrate obtainable according to a method of claims 1 to 13, wherein the carbon of the DLC layer is a mixture of sp ³ - and sp ² - hybridized carbon with a proportion of at least 40% sp ³ hybridized Includes carbon and the DLC layer means

High-power pulsed magnetron sputtering (HiPIMS) is deposited.

15. Coated substrate according to claim 14, wherein on the substrate are applied in this order a. a layer of diamond-like carbon (DLC), b. a release layer composed of one or more layers, each layer independently of one another being a metallic or a nitridic layer, and c. an anti-oxidation layer.