EP3286584A1

EP3286584A1 - Coated optical object and method for producing a coated optical object

Info

Publication number: EP3286584A1
Application number: EP16717594.2A
Authority: EP
Inventors: Michael Vergöhl; Stefan Bruns; Hans-Ulrich Kricheldorf; Lothar SCHÄFER; Markus Höfer; Markus Armgardt
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 2015-04-24
Filing date: 2016-04-13
Publication date: 2018-02-28
Also published as: DE102015106368A1; DE102015106368B4; WO2016169825A1; CN108112266A; JP2018513423A; JP6713485B2; US20180136369A1

Abstract

The invention relates to a coated object (100) which comprises a substrate (1) and an optical coating (2) arranged on the substrate (1). The optical coating (2) has a reflection-reducing layer sequence (3) which comprises a cover layer (4) with a refractive index nA and at least one diamond layer (5) with a refractive index nD1> nA. The diamond layer (5) is arranged between the cover layer (4) and the substrate (1) and has diamond crystals or consists thereof, said diamond layer (4) having a thickness of less than 500 nm.

Description

description

COATED OPTICAL OBJECT AND METHOD FOR PRODUCING A COATED OPTICAL OBJECT

The invention relates to a coated article. Furthermore, the invention relates to a method for producing a coated article. Articles with a coating, in particular with a visible antireflection coating, are widely used industrially. It is therefore to this

coated high demands, since they are sometimes exposed to strong mechanical stresses. However, today's coatings show in apparently relatively undemanding tests, such as the

Sandrieseltest, after a short time heavy wear due to cloudiness or abrasion. Therefore, coatings are necessary which withstand durable abrasive stresses partly under extreme conditions and are insensitive to shocks.

One problem to be solved is to provide a stable and reflection-reducing or reflection-reduced

to provide coated article. In particular, the coating of the coated article should - in addition to a low reflection - have a high hardness and / or scratch resistance. This object is achieved by a coated article according to independent claim 1. advantageous

Embodiments and developments of the invention are

Subject of the dependent claims. Furthermore, this will Problem solved by a method for producing a coated article according to claim 9.

Advantageous embodiments and further developments of

Method are the subject of dependent claim 10.

In at least one embodiment, the coated article comprises a substrate. On the substrate, an optical coating is arranged. The optical coating has a reflection-reducing layer sequence. The

reflection-reducing layer sequence comprises or comprises a cover layer with a refractive index n ^ and at least one diamond layer with a refractive index np _] _> n ^. The diamond layer is between the cover layer and the

Substrate arranged. The diamond layer points

Diamond crystals on. In particular, the diamond layer consists of diamond crystals or diamond nanocrystals. The

Diamond layer has a layer thickness of <500 nm.

According to at least one embodiment, the

reflection-reducing layer sequence a reflectance of less than or equal to 3%, in particular of less than 1%, on. Alternatively or additionally, the diamond layer has a transmission of greater than 80%, in particular greater than 90%, for example more than 95%, at least in one

Wavelength range from 420 nm to 680 nm, ie in the visible wavelength range on.

According to at least one embodiment, the

reflection-reducing layer sequence on a reflectance of less than 1% in a wavelength range of 420 nm to 680 nm. In addition, the diamond layer between the cover layer and a second layer with a

Refractive index ri2 <np _] _ be arranged, the Covering layer and the diamond layer are mechanically directly in contact and / or wherein between the diamond layer and the cover layer, a first layer having a refractive index n] _ is arranged, where: np] _>ri2> ⁿ l.

According to at least one embodiment, the

coated object a substrate. The substrate may be any article suitable for coating.

In particular, the substrate is formed of glass such as quartz glass or sapphire. In particular, the substrate is made of a transparent material, such as glass, quartz glass or sapphire. The substrate may be an optical component. optical

Components are, for example, lenses, in particular for binoculars, endoscopes or optical sensors. The substrate can also be, for example, a consumer good, for example a watch, a smartphone, a smartwatch or fingerprint sensors or displays of mobile phones or watches. In particular, the substrate is a glass for a clock. The substrate can be an object from the field of

Photovoltaic, solar thermal, such as solar cells, architecture and / or the automotive industry.

For example, the substrate is a sunroof of a car. The substrate may be part of different products on the market.

The substrate can be an object from the field of

Be medical technology. For example, the substrate is the end glass of an endoscope. In particular, the coated article may also be new

Find applications where conventional coated

Items have not been used yet.

For example, the optical coating for the Coated article according to the invention in a harsh environment, for example in desert climates, or in oil drilling systems

Find application. The coating can also be used in areas where equipment is sterilized, which is carried out at high pressure, for example 5 bar and / or high temperature, for example 135 ° C. These pressures or temperatures can be used in steam sterilization in the

Autoclave present. The inventors have realized that by using an optical coating on an inventive

coated object, an article or a product can be provided which is insensitive to abrasive stresses, wear, abrasion, shock, scratches and / or environmental influences, such as corrosion. In addition, the optical coating has an anti-reflection, ie

especially a reflection of less than 1% in the visible range. In particular, the inventive

An article according to claim 1 in comparison to other already existing technical solutions an extreme

Scratch resistance on.

Heretofore, visible reflection-reducing optical coatings are known which do not have sufficient hardness. For example, these coatings have a maximum hardness of the material of about 10 GPa. The inventors have now recognized that by using an optical coating in a coated article according to claim 1, a coated article can be provided which is very hard and has a layer hardness of 60 to 100 GPa. Therefore, a superhard

Antireflection coating are provided on an object. In accordance with at least one embodiment, the coated article has an optical coating. The optical

Coating has a layer sequence, in particular a reflection-reducing layer sequence. With

In this context and in the following, it is meant that the layer sequence has a reflection or a degree of reflection of less than or equal to 3%, in particular less than 1% in the visible range, ie at least in one

Wavelength range from 420 nm to 680 nm.

The layer sequence comprises a cover layer. With

Covering layer is here and below the layer of

Layer sequence meant the furthest to the substrate

turned away. In other words, the capping layer is the outermost layer of the optical coating. The

Covering layer has a refractive index n ^.

In accordance with at least one embodiment, the cover layer comprises a material selected from the group consisting of alumina, silica, aluminum nitride,

Silicon nitride, crystalline alumina and a mixture of Al2O3 and S1O2 S1 ₃ N ₄ or A1N includes.

In accordance with at least one embodiment, the covering layer is formed from crystalline aluminum oxide and / or has a layer hardness of> 15 GPa, in particular> 20 GPa,

for example, 25 GPa or 30 GPa, on. The hardness can be determined with nanoindentation or nanoindentor.

Alternatively or additionally, the diamond layer has a layer hardness of> 60 GPa.

Not only the hardness alone is decisive for the suitability of the layer in an optical coating. Therefore, you can In addition to the established nanoindentation for determining the hardness, practical tests, for example TABER-ABRASER and / or the sand-pouring test, can also be used. In addition, further investigations, for example on autoclaving, can be carried out.

The crystalline alumina may be, for example, an alpha alumina (corundum). Alpha alumina has a refractive index of 1.77 at a wavelength of 550 nm. Alpha alumina is very hard and has a hardness of 20 to 35 GPa. Alternatively or additionally, gamma or beta alumina may be used instead of alpha alumina.

Aluminum oxide is only possible in crystalline aluminum oxide phases with high ion bombardment and at high temperatures. This is especially true for the alpha-alumina phase

(Sapphire). Alpha-alumina is formed thermodynamically only from 1000 ° C. For a crystallization of

Aluminum oxide layer, the ion bombardment must be as high as possible. Therefore, it is possible in particular to work with biases on the substrate as well as with highly ionized plasmas (HiPIMS). The bias must be especially at isolating

Substrates be high frequency. Here are enough depending on

Substrate thickness medium frequencies up to approx. 300 kHz. Alternatively, a radio frequency bias voltage can be used.

According to at least one embodiment, the cover layer has at most a refractive index n _A of 1.76. As a result, a reflection of less than or equal to 1% can be achieved.

In accordance with at least one embodiment, the covering layer comprises a mixture of aluminum oxide and silicon dioxide, that is to say one crystalline Al 2 O 3 -SiO 2 mixed layer, in particular a crystalline Al 2 O 3 -SiO 2 mixed layer on. Thus, the refractive index of the covering layer may vary depending on the mixing ratio between the refractive index of alumina (1,7) and

Silicon dioxide (1.5) can be adjusted individually.

However, the admixing of silicon dioxide makes crystallization more difficult and reduces hardness.

In particular, the mixed layer of aluminum oxide and silicon dioxide has the empirical formula a S1O2 * b Al2O3. The mixing ratios a: b and layer thicknesses are in the EP

2628818 AI stated. The disclosure of this application is hereby incorporated by reference.

In accordance with at least one embodiment, the covering layer has a layer thickness of from 10 nm to 300 nm, in particular from 50 nm to 150 nm, particularly preferably from 60 nm to 90 nm. In particular, individual layer thicknesses are very specific to the stack design or layer sequence used. In accordance with at least one embodiment, the coated article has at least one diamond layer. The

Diamond layer has a refractive index np _] _ on. Of the

Refractive index is in particular greater than the refractive index n ^ of the cover layer. The diamond layer is disposed between the cover layer and the substrate.

The fact that a layer is arranged between two other layers can, here and below, mean that the one

Layer is arranged directly in direct mechanical contact or in indirect contact with one of the two other layers and in direct mechanical contact or in indirect contact with the other of the two other layers. In this case, in indirect contact then more layers between one and at least one of the other two

Layers can be arranged.

The diamond layer may include diamond crystals.

In particular, the diamond crystals have one

polycrystalline and / or nanocrystalline layer structure. In particular, the diamond layer consists of

Diamond crystals. The diamond layer is by means of chemical

Vapor deposition (CVD)

available. In particular, the diamond layer is produced by means of HFCVD (hot filament CVD, hot-wire vapor deposition). In the HFCVD or in others

Diamond production processes are subject to high temperatures and extreme conditions because of the presence of atomic hydrogen.

According to at least one embodiment, the

Vapor deposition plasma CVD.

In this case, a gaseous hydrocarbon, such as methane, can be introduced into hydrogen in a reaction chamber, wherein the process gases are hydrogen and a gaseous

Hydrocarbon, usually methane, and optionally also admixtures of oxygen on a hot wire, such as tungsten, molybdenum or tantalum, at a temperature of 800 to 2500 ° C, for example 2000 to 2500 ° C, are decomposed. The decomposed process gas leads to

Deposition of diamond on the substrate.

Alternatively, it is also possible to produce diamond layers by means of plasma CVD. Radio frequency Waves, but preferably microwaves are used. Here, the free radicals are not like the HFCVD

catalytically generated by hot wires, but by the plasma.

To avoid optical scattering in the at least one diamond layer, the dimensions of the resulting

Crystal structures well below the wavelength of

visible light. This requires a lot

Defect-free and finely crystalline poly- and / or nanocrystalline layer. Compared to a diamond layer with coarsely crystalline layers, the at least one

Diamond layer on a higher grain boundary density. This reduces the hardness of the diamond layer and can too

Lead to absorption losses. Prerequisite for the production of at least one diamond layer is the attainment of very high and uniform nucleation densities of> 10-2 cm ^~ 2 in an adapted to the foregoing coatings

Pretreatment step.

Especially before the application of at least one

Layer of layers produced diamond layer must be stable to the prevailing in hot wire gas phase process high temperatures, for example, 600 to 900 ° C. Alternatively, you can work in a process with lower substrate temperatures up to 500 ° C. Furthermore, the layers of the layer sequence must be stable to the action of atomic hydrogen.

Hydrogen radicals may chemically reduce previous oxide layers, for example, first layers and / or second layers, resulting in substoichiometric

Boundary layers with altered optical properties could result. In particular, those before the at least one Diamond layer deposited layers of the layer sequence compatible and / or stable to high temperatures at least between 500 and 900 ° C, in particular between 600 ° C and 900 ° C.

In particular, the diamond layer has a low scattering, high transmission and / or good stoichiometry

In particular, a small influence of the seed layer is present. In particular, the seed layer is formed very thin.

According to at least one embodiment, the

Diamond layer on a layer thickness of <500 nm.

In particular, the diamond layer has a layer thickness of 50 to 200 nm, in particular 60 to 150 nm, for example 130 nm.

The diamond layer, which is produced in particular by hot-wire vapor deposition, has a high optical transparency. With transparent here and below a layer is called, which is permeable to visible light. In this case, the transparent layer can be transparent or at least partially light-scattering and / or partially light-absorbing, so that the transparent layer can also be translucent, for example, diffuse or milky. Particularly preferably, the layer designated here as transparent as possible is translucent, so that in particular the absorption and also the scattering of

visible light as low as possible. According to at least one embodiment, the diamond layer is homogeneous and / or uniformly shaped. By this is meant here and below that the diamond layer has a nearly uniform layer thickness, for example a uniform one Layer thickness, with a tolerance of less than or equal to 10 or 1%. This homogeneous layer thickness can be generated in particular by means of hot-wire vapor deposition. In particular, with regard to the layer uniformity, specifications must be met which far exceed those of other technology fields in which diamond layers are otherwise used. The exceptionally high

Thickness uniformity is due to special adjustments of the

Coating process achieved in the HFCVD process

for example, by extremely precise control of the distance of the activation wires to the substrate surface and the

Arrangement of the wires with each other, so as to achieve the most uniform activation of the gas phase. Another measure for the realization of particularly homogeneous

Layer thicknesses can be the translational or rotational movement of the substrate during the coating, with the remaining residual uniformities being averaged out. In particular, the HFCVD process offers particularly good preconditions compared to other processes which are suitable for diamond coating, because here there are no (high-frequency) electric fields at or in the vicinity of the substrate

needed. It can be used to achieve a particularly uniform diamond deposition, especially at the edges of the substrates to be coated special Umsetzungskörper and masks, with which edge overshoots are reduced. Another proven measure for

Control of the layer thickness distribution can be targeted

Be flow of the substrate surfaces with the process gases. According to at least one embodiment, the

Layer sequence at least four layers, in particular at least five or six or seven layers on. Of these, one or more layers may be diamond layers. Alternatively or additionally, the layer sequence has at most twelve layers, for example a total of five or seven layers. In principle, the number of layers is not limited to the top. In particular, at least one diamond layer and a covering layer are part of the

Layer sequence. For economic reasons, the optical coating should not exceed a number of layers of twelve. In particular, the diamond layer has a layer thickness of less than or equal to 300 nm.

The layer sequence is a composite, so that the complete stack is to be examined. The production of the diamond layer is the most expensive. Therefore, it is advantageous if possible only a diamond layer within the

Layer sequence to use. Apart from this practical reason, however, the method is also applicable to a layer stack having more than one diamond layer.

In accordance with at least one embodiment, the diamond layer is arranged between the cover layer and a second layer with a refractive index ri2 <np _] _. The cover layer and the diamond layer are in particular in direct mechanical contact with each other. Alternatively, a first layer is disposed having a refractive index _n] _ between the diamond layer and the cover layer. Where np _] _>ri2> n _] _. By "directly arranged" here and in the following means that the one layer is arranged directly in direct mechanical contact with the other layer, in other words, in particular a coated article is provided which comprises a diamond layer at least as the second uppermost or third uppermost layer of the optical coating The cover layer then forms the top layer of the optical coating. By incorporating a diamond layer in an optical coating,

especially for the visible spectral range (420 to 680 nm) can be a hard and stable optical coating

be provided because the diamond to be surpassed by no other material hardness of> 60 GPa

having .

In addition, the cover layer of crystalline

Alumina can be formed with a hardness of> 20 GPa. Thus, an optical coating can be provided for an article which is a superhard one

Broadband antireflective coating for any application provides. In particular, the combination of

crystalline diamond in combination with crystalline

Alumina (sapphire) an optical coating that has a high layer hardness, especially when properly matched layer thicknesses, and a high anti-reflection function. According to at least one embodiment, the

Diamond layer has a refractive index of 2.4 at 550 nm. By combining the materials of diamond and

Alumina can be realized, in particular by using further underlying layers necessary for the optics, a new super-hard antireflective coating for an article which far exceeds the stability of the hitherto known coatings.

In addition, a durable optical coating can be provided for any application.

According to at least one embodiment, the second

Layer a material selected from the group 1O2 (refractive index 2.45-2.65), b2Ü5 (refractive index 2.3), Al2O3 (refractive index 1.60-1.77), S13N4 (refractive index 1.9 to 2.1), Hf02 (refractive index 2, 08) and Zr02

(Refractive index 2.15). In particular, the refractive indices indicated in brackets are for 550 nm.

In particular, Al 2 O 3 is used for the second layer, since titanium dioxide has a high refractive index of 2.45

has, however, is very soft. Niobium oxide has a refractive index of 2.3, but is softer than

Titanium dioxide.

By using a diamond layer with a high refractive index and a high hardness, the entire

Layer sequence stabilized and supported. Thus, the cover layer is stabilized and supported, so that the optical coating has a higher overall stability. Thus, the optical coating is in particular very scratch resistant.

In accordance with at least one embodiment, the first layer comprises or consists of silicon dioxide. Silica has a refractive index of 1.45. According to at least one embodiment, the

Layer sequence additionally one or more pairs of layers. The pairs of layers are arranged directly downstream of the substrate, ie in direct mechanical contact. The

Layer pairs each have at least one first layer, in particular a first layer, with a refractive index n _] _ and at least one second layer, in particular a second layer, with a refractive index n2> n _] _. The

Diamond layer is between the first and second layers arranged a layer pair. Alternatively or additionally, the diamond layer is arranged directly downstream of one or more pairs of layers, ie in direct mechanical contact. Over the diamond layer, the cover layer is arranged. "Above" here and below means that one layer is disposed directly in direct mechanical and / or electrical contact on the other layer. Furthermore, it may also mean that the one layer is arranged indirectly above the other layer. It can then more layers between the one and the other layer

be arranged. In particular, the cover layer and the diamond layer are arranged in direct mechanical contact with each other. In particular, apply: np] _> r i2> n ^ and n] _ ^<n A - ⁿ 2 ^an d ⁿ Dl> Π2 + x * 0.6 0.1 S x S 1. In particular, apply to x : 0.7 <x <1. Alternatively, np] _ < ⁿ 2 ^{> n} l ^and dn] _ <Ώ.2 ^ n2.

In accordance with at least one embodiment, the layer sequence is for transmission of radiation having a dominant

Wavelength λ suitable. The following applies: for the thickness of the

Diamond layer 0.1 λ / 4 <np] _ * d _Q ] _ ^ 1.3 λ / 4 and / or for the thickness of the covering layer 0.1 λ / 4 <n _A * d ^ <1.3 λ / 4 and / or for the thickness of the first layer 0.1 λ / 4 <n ^ * d ^ <1.3 λ / 4 and / or for the thickness of the second layer 0.1 λ / 4 <n2 * d2 ^ 1, 3λ / 4. In particular: for the thickness of the diamond layer 0.3 λ / 4 <n _D ^ * d _D i <0.8 λ / 4 and / or for the thickness of

Cover layer 0.7 λ / 4 <n ^ * d ^ -S 1.3 λ / 4 and / or for the thickness of the first layer 0.7 λ / 4 <n] _ * d] _ ^ 1.3 λ / 4 and / or for the thickness of the second layer 0.7 λ / 4 <n2 * d2 ^ 1.3 λ / 4.

According to at least one embodiment, the

Layer sequence at least one additional diamond layer, hereinafter referred to as second diamond layer, with a Refractive index n ^ on. The second diamond layer is disposed between the cap layer and the substrate.

In particular, the second diamond layer is disposed between the first diamond layer and the substrate. The two diamond layers are separated by a first layer having a refractive index _n] _ and / or by a second layer having a refractive index RI2 each other. The

Covering layer is in particular directly downstream of one of the diamond layers, in particular the first diamond layer. Where: > n _] _ + 0.4 and / or n] _> r \ 2 + 0.2 and / or ^η ^ 2> ⁿ 2 ⁺ 0.2 and / or ^η ^] _ = ^η ^ 2

and / or n] _> n2 + = ⁿ D2

In particular, the first layer may be formed of silicon dioxide and / or the second layer may be formed of aluminum oxide. This can be a coated object

provided a hard and scratch-resistant and environmentally stable optical coating

having .

The invention further relates to a method for producing a coated article. The same explanations and definitions as described above for the article also apply to the method and vice versa. In accordance with at least one embodiment, the method has the

Method steps on: A) Providing a substrate and

B) applying a reflection-reducing layer sequence, wherein the at least one diamond layer by means of Vapor deposition, in particular chemical

Gas phase deposition, such as hot wire vapor deposition or microwave CVD is generated and then the cover layer is produced by magnetron sputtering.

The pretreatment and vapor deposition, in particular hot wire vapor deposition, are to be designed such that the most uniform and absorption-free

Diamond layer is grown and a stable interface between the diamond layer and the adjacent layers or the substrate arise. The

Absorbency of the diamond layer can by the

Use of low concentrations of the hydrocarbon, especially at concentrations greater than or equal to 1%. Methane diluted in up to 99% hydrogen, and / or

Activation of the gas phase by high wire temperatures in the HFCVD process and / or high power densities,

For example, in microwave activated CVD can be achieved.

In accordance with at least one embodiment, the diamond layer is directly followed by a silicon nitride layer. The

Silicon nitride layer has in particular a layer thickness of a few nanometers or some 10 nm to a few 100 nm, for example between 20 nm and 300 nm. As a result, the diamond surface can be protected from ion bombardment by the subsequent coatings, for example by means of magnetron sputtering, and the adhesion of the diamond layer to adjacent oxidic layers can be improved. The silicon nitride layer can be produced in particular by hot-wire vapor deposition and / or magnetron sputtering. Alternatively, the diamond layer of a

Silicon nitride layer directly downstream to the

To improve adhesion of the diamond layer and / or to

prevent the reduction of oxide layers by atomic hydrogen.

Among magnetron sputtering is in particular the pulsed

meant reactive magnetron sputtering. In particular, magnetron sputtering involves the high power impulse magnetron

Sputtering (HiPIMS). In particular, oxide-containing and / or nitride-containing layers are produced by means of magnetron sputtering.

Furthermore, the vapor deposition, in particular hot-wire vapor deposition, is used here for applying the at least one diamond layer. Through the use of hot-wire vapor deposition, diamond layers with a uniform layer thickness can be produced. In particular, diamond layers can be produced on surfaces of 500 × 1000 mm 2. In particular, the diamond layers are thin and defect-free. This can be achieved in particular by carrying out highly potent germination procedures.

According to at least one embodiment, the

Gas phase deposition, in particular hot wire vapor deposition and magnetron sputtering in one

Apparatus. It can thereby be made possible that both the application of oxide and / or nitridic layers by means of magnetron sputtering as well as the deposition of at least one diamond layer in an apparatus. This saves costs, material, time and space. In addition, a vacuum break between the individual coatings can be avoided, whereby the adhesion between the individual layers potentially can be improved. In addition, one can

Coating plant that combines both deposition processes, offering the possibility of economically producing layer systems with more than one diamond layer. The combination of hot wire vapor deposition for diamond layers and magnetron sputtering for oxide and / or nitridic layers ensures that a coated article is provided having a stable, scratch resistant and hard optical coating. Alternatively, instead of magnetron sputtering, too

Electron beam evaporation take place and instead of hot wire vapor deposition, other methods for

Diamond deposition can be used, for example

microwave-excited gas phase separation.

In particular, a coated article with an optical coating is provided, which in particular has a dielectric layer sequence with at least one

Diamond layer has. The diamond layer can take the position of a high refractive index layer. The diamond layer may be on a sputtered oxide layer and on the

Diamond layer in turn applied an oxide layer.

Compared to previously known coatings,

For example, from silicon dioxide and titanium dioxide, inventive optical coatings for an article have a high hardness, scratch resistance, high stability even against environmental influences and also a very low residual reflection.

Advantages, advantageous embodiments and developments will become apparent from the following in connection with the

Figures described embodiments. 1 is a schematic representation of a coated article according to an embodiment, a schematic illustration of a coated article according to an embodiment, the reflectance in percent as a function of the wavelength λ in nm of a comparative example and of two exemplary embodiments, and a schematic representation of a coated article according to FIG an embodiment.

In the exemplary embodiments and figures, identical, identical or identically acting elements can each be provided with the same reference numerals. The illustrated elements and their proportions with each other are not to be regarded as true to scale. Rather, individual elements, such as layers, for the better

Representability and / or for exaggerated understanding are exaggerated. In particular, the layers or the illustrated layer thicknesses are not to scale.

FIG. 1 shows a schematic side view of a coated article 100. The coated article 100 has a substrate 1. The substrate 1 can

for example, be made of glass or sapphire. Downstream of the substrate is a first layer 6 with a

Refractive index n _] _. The first layer 6 may comprise, for example, silicon oxide or silicon dioxide or from it consist. The first layer 6 is followed by a second layer 7 with a refractive index ri2. The second layer 7 may for example consist of aluminum oxide or

Include alumina. The second layer 7 is followed by a further first layer 6, which in turn

In particular, may comprise silicon oxide or silicon dioxide. This further first layer 6 is in turn subordinate to a further second layer 7, for example

May comprise alumina. The coated article 100 thus has as an optical coating 2 a

reflection-reducing layer sequence 3, the two

Having layer pairs, which are arranged downstream of the substrate 1 and each having a first layer 6 and a second layer 7. These two pairs of layers is one

Diamond layer 5 directly, ie in direct mechanical

Contact, downstream. In particular, the diamond layer 5 has a layer thickness of 50 nm to 150 nm, for example 130 nm. The diamond layer 5 is directly followed by a further first layer 6, which comprises, for example, silicon oxide or silicon dioxide. This further first layer 6, the cover layer 4 is arranged downstream of the uppermost layer. The cover layer 4 may be, for example, crystalline

Have alumina or a mixture of alumina and silica to reduce the refractive index. The coated article 100 according to FIG. 1 thus has a layer sequence 3 consisting of seven

Layers on. The layer sequence 3 may in particular have a layer thickness of 540 nm in total. Thus, a coated article 100 can be provided which has a scratch-resistant and hard antireflective coating 2 for at least the visible spectral range. FIG. 2 shows a coated article 100 according to an embodiment. The coated article 100 has a substrate 1. The substrate 1 is followed by a layer sequence 3 of an optical coating 2. The

Layer sequence 3 comprises two second layers 7 each having a refractive index of ri 2 · one of the two second ones

Layers 7 are arranged directly on the substrate 1. The second layer 7 is a first layer 6 with a

Refractive index n _] _ downstream. The first layer 6 is followed by a further second layer 7. The further second layer 7 is followed by a diamond layer 5. Of the

Diamond layer 5 is a cover layer 4 downstream. The cover layer 4 is the outermost layer of the optical

Coating 2. Thus, the diamond layer 5 is the penultimate layer 5 of the optical coating 2, which follows directly after the covering layer 4. The coated article 100 according to FIG. 2 thus has a layer sequence 3 consisting of five layers. The total thickness of the optical coating 2 may be about 540 nm. The cover layer 4 has

especially crystalline alumina and silica. In particular, silica is blended to reduce the refractive index of alumina (1.7).

FIG. 3 shows a graphical representation of the reflection or the degree of reflection R in percent (%) as a function of the wavelength in nanometers (nm).

Graph A shows the reflectance in percent of

Embodiment of Figure 1. In particular, the coated article 100 according to the figure 1 a

Reflectance R of <1%, in particular less than 0.8% in the visible range, ie between 420 nm and 680 nm, on. Graph B shows the reflectance or reflection in percent of the embodiment of FIG

Coated article 100 according to FIG. 2 shows a reflectance R between 1.8% and 3% in the visible

Spectral range between 420 and 520 nm. Between 520 nm and 580 nm, R is between 0.8% and 1.8%. In the wavelength range of 580 to 640 nm, the embodiment of Figure 2 has a reflectance R of less than 1%. Between 640 and 680 nm, the reflectance is less than 2%.

Figure C shows the percent reflectance of sapphire in a wavelength range of 360 nm to 800 nm. Sapphire shows a reflectance of about 8%. All reflection values

refer to a page, that is, without the inclusion of the back reflection. Reflection or reflectance refers here and below to the relationship between reflected and incident intensity.

FIG. 4 shows a schematic representation of a

coated article 100 according to one embodiment.

The coated article 100 shows a substrate 1. On the substrate 1 is an optical coating 2 with a

reflection-reducing layer sequence 3 is arranged. The layer sequence 3 has two diamond layers 5, 8. The first diamond layer 5 is arranged directly below the cover layer 4. The two diamond layers 5, 8 are each separated by a first layer having a refractive index n _] _ and / or a second layer having a refractive index ri2 6, 7. In particular: np _] _> n _] _ + 0.8 and n ^ 2> n] _ + 0.8 and / or n ^] _> r \ 2 + 0.4 and n ^ 2> ⁿ 2 ⁺ 0.4 and / or np] _ = np2 · In particular, the first layer 6 is formed of silicon dioxide. In particular, the second layer 7 is made

Shaped aluminum oxide. The cover layer 4 is formed in particular from crystalline aluminum oxide. Alternatively, more than two diamond layers 5, 8 in one

coated article 100 are introduced.

For example, three, four, five or six

Diamond layers in a coated article

be introduced. In particular, the production of the diamond layer by means of hot-wire vapor deposition is particularly complex. Therefore, it is preferable to have as few diamond layers as possible in a coated one

To bring in item 100. The ones described in connection with the figures

Embodiments and their features can also be combined with each other according to further embodiments, even if such combinations are not explicitly shown in the figures. Furthermore, the embodiments described in connection with the figures may have additional or alternative features as described in the general part.

The invention is not limited by the description based on the embodiments of these. Rather, the invention encompasses every new feature as well as every combination of features, which in particular includes any combination of features in the patent claims, even if this feature or combination itself is not explicitly described in the claims

Claims or embodiments is given.

Claims

claims

A coated article (100) comprising

a substrate (1),

- An on the substrate (1) arranged optical coating (2), wherein the optical coating (2) a

reflection-reducing layer sequence (3) comprising a cover layer (4) with a refractive index n ^ and at least one diamond layer (5) with a refractive index np _] _> n ^, wherein the diamond layer (5) between the

Cover layer (4) and the substrate (1) is arranged and has diamond crystals or consists thereof, wherein the diamond layer (4) has a layer thickness of less than 500 nm.

2. Coated article (100) according to claim 1,

wherein the reflection-reducing layer sequence (3) has a reflectance of less than 1% in a wavelength range of 420 nm to 680 nm,

wherein the diamond layer (5) is arranged between the cover layer (4) and a second layer (7) with a refractive index ri2 <crack_, the cover layer (4) and the

Diamond layer (5) are mechanically directly in contact and / or wherein between the diamond layer (5) and the

Covering layer (4) has a first layer (6) with a

Refractive index n _] _ is arranged, where: np _] _>ri2> n _] _.

3. Coated article (100) according to one of

previous claims,

wherein the layer sequence (3) additionally one or more

Having layer pairs, which are directly downstream of the substrate and in each case a first layer (6) with a Refractive index and a second layer (7) with a

Refractive index ri2> n _] _ have,

wherein the diamond layer (5) is arranged between the first and second layer (6, 7) of a pair of layers, or wherein the one or more pairs of layers

Diamond layer (5) is arranged directly downstream, wherein over the diamond layer (5) the cover layer (4) is arranged, where: np] _> ri2> n ^ and n] _ <n ^ <ri2 and np] _> ri2 + x * 0.6 with 0.1 x 1 or

where np _] _ <ri2> n ^ and n _] _ <n ^ <n ₂ .

4. Coated article (100) according to one of

previous claims,

wherein the layer sequence (3) has at least five layers and / or at most twelve layers, and wherein the diamond layer (5) has a homogeneous layer thickness with a

Layer thickness less than or equal to 300 nm.

5. Coated article (100) according to one of

previous claims,

wherein the cover layer (4) is formed of crystalline alumina and has a layer hardness measured with a

Nanoindentor, has greater than 20 GPa and / or the

Diamond layer (5) has a layer hardness of greater than 60 GPa.

6. Coated article (100) according to one of

previous claims,

wherein the cover layer (4) comprises a material selected from the group consisting of alumina,

Silicon dioxide, aluminum nitride, silicon nitride, crystalline alumina and a mixture of Al2O3 and S1O2, S1 ₃ N ₄ or AlN.

A coated article (100) according to any one of the preceding claims,

wherein the layer sequence (3) is suitable for the transmission of radiation having a dominant wavelength λ, wherein for the thickness of the diamond layer (5) 0.3 λ / 4 <n _D1 * d _D i ^ 0.8 λ / 4 and for the Thickness of the cover layer (4) 0.7 λ / 4 <n _A * d ^ <1.3 λ / 4 and for the thickness of the first layer (6) 0.7 λ / 4 <n _] _ * d _] _ ^ 1.3 λ / 4 and for the thickness of the second layer (7) 0.7 λ / 4 <n ₂ * d ₂ ^ 1.3 λ / 4 applies.

8. Coated article (100) according to one of

previous claims,

wherein the layer sequence (3) comprises at least one additional diamond layer (8) with a refractive index np2, which is arranged between cover layer (4) and substrate (2), wherein the at least two diamond layers (5, 8) of the

Layer sequence by a respective first layer (6) with a refractive index n _] _ and / or a second layer (7) with a refractive index n ₂ are separated from each other, wherein the covering layer (4) of one of the diamond layers (5, 8) is arranged directly downstream , where np _] _> n _] _ + 0.8 and np2> n] _ + 0.8 and / or > ⁿ 2 ⁺ 0.4 and / or ⁿ Dl = ⁿ D2

9. A method for producing a coated article (100) according to any one of claims 1 to 8, comprising

Process steps:

A) providing a substrate (1), and

B) applying a reflection-reducing layer sequence (2), wherein the at least one diamond layer (5) by means of

Gas phase deposition is generated and then the cover layer (4) is produced by magnetron sputtering.

10. The method according to claim 9,

wherein the vapor deposition and the magnetron sputtering are carried out in an apparatus.

11. The method according to claim 9,

wherein the vapor deposition is plasma CVD.