DE4117257B4 - Optically effective coating system with high antireflection effect for transparent substrates - Google Patents

Abstract

Optically effective layer system for substrates, wherein the layer system has a high antireflection effect, characterized in that on the observer facing a front side of a substrate (1) in the local order from the substrate (1) to the viewer a first on the substrate (1) fitting , a dielectric-forming, metal oxide-containing layer (4) is arranged with a layer thickness of 80 Å +/- 20%, on which a second nitride-containing layer (5) is arranged with a layer thickness of 130 Å +/- 20%, on the back of the substrate (1) a TiN _x layer (8) is arranged with a layer thickness of 40 to 150 Å and the substrate (1) is transparent and has a refractive index of 1.5 to 1.65.

Description

The The invention relates to an optically active layer system for transparent Substrates, the Schichtsytem in particular a high anti-reflection effect having.

It gives a wide range of coating systems for substrates, especially for glass, which fulfill certain optical functions. The present invention relates to the genre of antireflection coatings or antireflective coating systems.

The publication DE 39 42 797 A1 describes a 5-layer system with high anti-reflection effect with a layer sequence of dielectric layer with metal oxide (A) and nitride layer (B) in a layer sequence, viewed from substrate: ABABA.

The US patent specification US 4,690,871 (Gordon) describes a tin oxide of 300-800 Å thick which protects an underlying titanium nitride layer during the annealing process. The titanium nitride layer functions as a heat shielding layer on a glass substrate.

By the German patent application 36 29 996 A1 is a header unit for the CRT of monitors, televisions and the like, consisting of a Glass pane, in particular a gray glass pane, a front side Antireflective equipment and a back From sorption coating, wherein the absorption coating metal atoms has become known.

In This German Offenlegungsschrift is proposed that the absorption coating single layer of chromium, a chromium / nickel alloy or silicides built and antistatic furnished and grounded and with a Thickness is provided, which is the light transmission over the uncoated glass panel lowers by about a third.

In US Pat. No. US 38 54 796 Furthermore, a coating is proposed which is intended to reduce the reflection. The coating is to be applied to a substrate having a plurality of layers. In the order beginning with the substrate, the following arrangement is described in the US patent specification: three groups of at least two lambda / 4 layers, the successive layers of the first group having a refractive index which is below the refractive index of the substrate. The layers of the second group have an increasing refractive index and the layers of the third group have a refractive index below the refractive index of the substrate. Further details can be found in the cited US patent.

The prior art still includes the US patent US 37 61 160 , There, a broadband reflection coating and substrates coated therewith are proposed. They have at least four layers for high index glass and at least six layers for low index glass. Further details can be found in the cited US patent.

Furthermore, in US Patent US 36 95 910 a method of applying an antireflection coating on a substrate is described. This coating consists of several individual layers. The method of applying the antireflection layers is done under vacuum using electron beams. Further details can be found in the aforementioned US patent.

The prior art still includes the Swiss patent CH 223344 , This document is concerned with a coating for reducing surface reflection. The coating consists of at least three layers with different refractive indices. The reduction of the surface reflection is to be achieved according to this document by a specific selection of the refractive indices of the individual layers.

Furthermore, in US Patent US 54 07 733 A a method for applying anti-reflection layers on substrates by reactive sputtering received. In particular, the optical properties of the TiN layer and other layers as well as their layer thickness dependency are described.

The invention is based on the following object:
It will create conditions for the economic production of anti-reflection coatings for transparent substrates.

transparent Substrates are needed in a variety of modern equipment and devices. The manufacturer of these facilities and equipment make high demands in terms of optical and other Properties of these substrates.

The Invention is intended to meet these stringent requirements in particular on the anti-reflective coating, the increase in contrast and the increase in Fulfill antistatic effect.

Farther should be prerequisites for this be created that one only a small number of layers is needed. At the same time the thicknesses of the individual layers are small. The invention is made continue to the task, conditions for the use of cheaper To create materials.

With The invention is a concept to be proposed, in the DC-reactive can be sputtered from the metal target with magnetron.

The small number of layers of the layer system, the small thickness the individual layers of the layer system, the choice of cheaper Feedstock and the ability to Sputtering DC reactive with magnetron from the metal target results a very economical one Production of the Antireflective Layer Systems According to the Invention

At the use of metal layers for antireflection systems is in principle known. However, it has been found that the known metal layers for the Everyday operation are too soft.

It belongs Therefore, with the task of the present invention, a Replacement for to find the known soft metal layers (Ag, Ni, ...). This Replacement should be hard and scratch resistant. He should on the one hand a ceramic Have hardness, on the other hand, however, the effect of a metal-like Own optics.

The objects are achieved according to the invention with the features of claim 1, characterized in that on the viewer side facing the substrate (front) in the local order from the front to the viewer a first on the substrate adjacent, forming a dielectric, metal oxide layer is disposed, hereinafter a second nitride, preferably TiN _x , having layer is arranged and subsequently a third layer forming a dielectric metal oxide layer is arranged.

It can be provided that the first layer of oxides from the group: SnO ₂ , ZrO ₂ , ZnO, Ta ₂ O ₅ , NiCr oxide, TiO ₂ , Sb ₂ O ₃ , In ₂ O ₃ or mixed oxides of oxides from this group includes.

Farther It is suggested that the second layer of nitrides from the group TiN, ZrN comprises.

It has proven to be advantageous for the third layer to comprise low-index materials, in particular having a refractive index n equal to or smaller than 1.7, and oxides from the group SiO ₂ , Al ₂ O ₃ , AlSi oxide, NiSi oxide, MgO or Oxide fluorides from the same group includes.

Alternatively, it may be provided that the third layer comprises MgF ₂ .

In a group of embodiments It is suggested that between the first and the second layer, a bonding agent layer arranged is.

Farther It is suggested that the Substrate in particular is transparent and preferably a refractive index from 1.5 to 1.65.

For at least one TiN _x layer is further proposed that over-stoichiometric for the described system layer TiN _x is used with x in the range 1 to 1.16.

In one embodiment, it can be provided that all TiN _x layers described.

Layer systems have TiN _x with x in the range of 1 to 1.16.

Further Details of the invention, the task and achieved Advantages are the following description of several embodiments to remove the invention.

These embodiments be based on five Figures explained.

The 1 . 2 and 5 each show a layer system.

The 3 and 4 show transmission and reflection curves in percent over the wavelengths in nm.

In the following, five exemplary embodiments are described below:
The substrate 1 is made of glass. The front 2 of the substrate is the side of the substrate facing the viewer. The backside 9 of the substrate is the side facing away from the viewer.

The layer applied to the front side of the substrate is called a "first" layer 4 designated. It follows in the direction of the viewer, the "second" layer 5 and the "third" layer 6 ,

• – auf der Rückseite des Substrats Glas ist eine optisch wirksame TiN_x-Schicht 8 angebracht,
• – in Richtung auf den Betrachter folgt das Substrat Glas 1,
• – die erste optisch wirksame Schicht 4, die am Substrat anliegt, besteht aus SnO₂,
• – die zweite optisch wirksame Schicht 5, die in Richtung auf den Betrachter der ersten optisch wirksamen Schicht folgt, besteht aus TiN_x,
• – die dritte optisch wirksame Schicht 6, die in Richtung auf den Betrachter der zweiten optisch wirksamen Schicht folgt, besteht aus Al₂O₃.

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

• - on the back of the substrate glass is an optically effective TiN _x layer 8th appropriate,
• - In the direction of the viewer follows the substrate glass 1 .
• The first optically active layer 4 , which bears against the substrate, consists of SnO ₂ ,
• - The second optically active layer 5 which follows the first optically active layer in the direction of the observer, consists of TiN _x ,
• The third optically active layer 6 , which follows in the direction of the viewer of the second optically active layer, consists of Al ₂ O ₃ .

• – auf der Rückseite des Substrats Glas ist eine optisch wirksame TiN_x-Schicht 8 angebracht,
• – in Richtung auf den Betrachter folgt das Substrat Glas,
• – die erste optisch wirksame Schicht 4, die am Substrat anliegt, besteht aus SnO₂,
• – es folgt in Richtung auf den Betrachter eine Haftvermittlerschicht 7, bestehend aus NiCrO_x,
• – die zweite optisch wirksame Schicht 5, die in Richtung auf den Betrachter folgt, besteht aus TiN_x,
• – die dritte optisch wirksame Schicht 6, die in Richtung auf den Betrachter der zweiten optisch wirksamen Schicht folgt, besteht aus Al₂O₃.

The layer system of the second embodiment is constructed as follows (see 2 ):

• - on the back of the substrate glass is an optically effective TiN _x layer 8th appropriate,
• In the direction of the observer, the substrate follows glass,
• The first optically active layer 4 , which bears against the substrate, consists of SnO ₂ ,
• - It follows in the direction of the viewer a bonding agent layer 7 consisting of NiCrO _x ,
• - The second optically active layer 5 that follows in the direction of the viewer consists of TiN _x ,
• The third optically active layer 6 , which follows in the direction of the viewer of the second optically active layer, consists of Al ₂ O ₃ .

• – auf der Rückseite des Substrats Glas ist eine optisch wirksame TiN_x-Schicht 8 angebracht,
• – in Richtung auf den Betrachter folgt das Substrat Glas 1,
• – die erste optisch wirksame Schicht 4, die am Substrat anliegt, besteht aus SnO₂,
• – es folgt in Richtung auf den Betrachter eine Haftvermittlerschicht 7, bestehend aus NiCr-Suboxid,
• – die zweite optisch wirksame Schicht 5, die in Richtung auf den Betrachter folgt, besteht aus TiN_x-Schicht,
• – die dritte optisch wirksame Schicht 6, die in Richtung auf den Betrachter der zweiten optisch wirksamen Schicht folgt, besteht aus SiO₂.

The layer system of the third embodiment is constructed as follows (see 2 ):

• - on the back of the substrate glass is an optically effective TiN _x layer 8th appropriate,
• - In the direction of the viewer follows the substrate glass 1 .
• The first optically active layer 4 , which bears against the substrate, consists of SnO ₂ ,
• - It follows in the direction of the viewer a bonding agent layer 7 consisting of NiCr suboxide,
• - The second optically active layer 5 , which follows in the direction of the observer, consists of TiN _x -layer,
• The third optically active layer 6 which follows in the direction of the viewer of the second optically active layer consists of SiO ₂ .

• – auf der Rückseite des Substrats Glas ist eine optisch wirksame TiN_x-Schicht 8 angebracht,
• – in Richtung auf den Betrachter folgt das Substrat Glas 1,
• – die erste optisch wirksame Schicht 4, die am Substrat anliegt, besteht aus NiCrO_x; diese Schicht 4 wirkt gleichzeitig als Haftvermittlerschicht,
• – die zweite optisch wirksame Schicht 5, die in Richtung auf den Betrachter folgt, besteht aus TiN_x,
• – die dritte optisch wirksame Schicht 6, die in Richtung auf den Betrachter der zweiten optisch wirksamen Schicht folgt, besteht aus SiO₂.

The layer system of the fourth embodiment is constructed as follows (see 1 ):

• - on the back of the substrate glass is an optically effective TiN _x layer 8th appropriate,
• - In the direction of the viewer follows the substrate glass 1 .
• The first optically active layer 4 , which bears against the substrate, consists of NiCrO _x ; this layer 4 acts simultaneously as a primer layer,
• - The second optically active layer 5 that follows in the direction of the viewer consists of TiN _x ,
• The third optically active layer 6 which follows the viewer toward the second optically active layer consists of SiO ₂ .

• – auf der Rückseite des Substrats Glas ist eine optisch wirksame TiN_x-Schicht 8 angebracht,
• – in Richtung auf den Betrachter folgt das Substrat Glas 1,
• – die erste optisch wirksame Schicht 4, die am Substrat anliegt, besteht aus NiCrO_x; diese Schicht 4 wirkt gleichzeitig als Haftvermittlerschicht,
• – die zweite optisch wirksame Schicht 5, die in Richtung auf den Betrachter folgt, besteht aus TiN_x,
• – die dritte optisch wirksame Schicht 6, die in Richtung auf den Betrachter der zweiten optisch wirksamen Schicht folgt, besteht aus Al₂O₃.

The layer system of the fifth embodiment is constructed as follows (see 1 ):

• - on the back of the substrate glass is an optically effective TiN _x layer 8th appropriate,
• - In the direction of the viewer follows the substrate glass 1 .
• The first optically active layer 4 , which bears against the substrate, consists of NiCrO _x ; this layer 4 acts simultaneously as a primer layer,
• - The second optically active layer 5 that follows in the direction of the viewer consists of TiN _x ,
• The third optically active layer 6 , which follows in the direction of the viewer of the second optically active layer, consists of Al ₂ O ₃ .

When Substrate can except Mineral glass, float glass also Plexiglas, transparent plastic layers, foils etc. are used.

In addition to the Vorderseitenentspiegelung by described, arranged in front of the front layer systems, a further surprisingly low total reflection is achieved by the arranged on the back side TiN _x layer. The basic idea of the invention allows for a multiplicity of exemplary embodiments or layer systems which are characterized by the materials and layer thicknesses mentioned below.

"First" layer (reference number 4 ), a dielectric:
Metal oxide (SnO ₂ , ZrO ₂ , ZnO, Ta ₂ O ₅ , NiCrO _x , TiO ₂ , Sb ₂ O ₃ , In ₂ O ₃ ,
Layer thickness: 80 angstroms ± 20

"Second" layer (reference numeral 5 ):
Nitride (TiN, ZrN)
Layer thickness: 130 angstroms ± 20

"Third" layer (reference number 6 ) Dielectric:
low-refraction materials, n less than 1.7 (SiO ₂ , Al ₂ O ₃ , AlSi oxide, NiSi oxide, MgO, MgF ₂ )
Optical thickness: 5550/4 Angstrom ± 10

"Primer layer" (reference numeral 7 ):
Ni, Cr, NiCr (80 wt% Ni, 20 wt% Cr)
Layer thickness: 10 Angstroms ± 10

On the back side 9 of the substrate is the "backside layer" (reference numeral 8th ) consisting of TiN _x , arranged,
Layer thickness: 40 to 150 angstroms.

It is self-evident, that such Values for the respective layer thickness within said layer thickness tolerance chosen be the interdependence of the individual layer thicknesses and the consider used materials to each other.

The following is the description of two examples of layer systems in which the reflection and the transmission in the visible wavelength range of the light were measured. The measurement results are graphically based on curves in the 3 and 4 shown.

In the description of the layer systems, the reference numbers of the description of the 1 used. The layer system of the first example is constructed as follows:
Substrate: glass ( 1 ), Thickness 2 mm, refractive index n = 1.52
Layer ( 4 ) Material: SnO ₂ thickness 90 angstroms, refractive index n = 2.05
Layer ( 5 ) Material: TiN _x , thickness 130 angstroms
Layer ( 6 ) Material: Al ₂ O ₃ , thickness 730 angstroms,
Refractive index n = 1.6
Layer ( 8th ) Material: TiN _x , thickness 70 angstroms

The in 2 7 designated adhesion promoter is not present in this embodiment.

For this Layer system were the reflection in percent and the transmission measured in percent, for a wavelength range from 400 nm to 700 nm.

In the following, the measurement results for the reflection and the transmission in a table are compared with specific wavelengths:

The results of the measurements are, as shown, as curves in 3 shown graphically. On the abscissa 10 of the coordinate system in 3 the wavelengths are entered in nm. On the left ordinate 11 of the coordinate system, the percentages for the reflection are entered. On the right ordinate 12 of the coordinate system, the percentage values for the transmission are entered.

It can clearly be seen from the curves that the reflection curve 14 is extremely low in the core wavelength region of visible light. It is well below 1%. Thus, the desired high antireflection effect has been achieved in a surprisingly clear manner. In the same nuclear wavelength range has the transmission curve 13 relatively high values. The layer system of the second example is characterized as follows:
Substrate: glass, thickness 2 mm, refractive index n = 1, 52
Layer ( 4 ) Material: NiCr oxide, thickness 70 angstroms, refractive index n = 2.1
Layer ( 5 ) Material: TiN _x , thickness 130 angstroms
Layer ( 6 ) Material: SiO ₂ thickness 790 angstroms,
Refractive index n = 1.5
Layer ( 8th ) Material: TiN _x , thickness 70 angstroms

A separate bonding agent, see reference number 7 , is absent in this embodiment.

For this Layer system were the reflection in percent and the transmission measured in percent, for a wavelength range from 400 nm to 700 nm.

In the following, the measurement results for the reflection and the transmission in a table are compared with specific wavelengths:

The results of the measurements are, as shown, as curves in 4 shown graphically. The abscissa and the ordinate are related to 3 described units of measure.

From the reflection curve 16 is clearly visible that the reflection in the range of about 560 nm wavelength has a pronounced low point. Thus, the desired high antireflection effect has been achieved convincingly by this example. The transmission curve 15 has its maximum in the core area of visible light.

To the transmission curve 13 ( 3 ) and to the transmission curve 15 ( 4 ) is basically to say the following:
Low transmission values of an auxiliary lens can be easily achieved by amplifying the. Light source, z. B. by turning the potentiometer on an LCD, be compensated.

The layer systems with which the above-commented transmission and reflection values were obtained were prepared by the method described below:
It was sputtered with magnetron in a reactive gas atmosphere.

Subsequently, the sputtering material is indicated in the left column and the reactive sputtering mixture in the right column: SnO ₂ Ar + O ₂ SiO ₂ Ar + O ₂ Al ₂ O ₃ Ar + O ₂ TiN Ar + O ₂ NiCr Ar + O ₂

Pressure during the sputtering process: approx. 5 × 10 ^-3 mb.

Target material: Sn, Si, Ti, NiCr (80 wt% Ni, 20 wt% Cr), Al.

On the front of the layer systems was a sheet resistance of 150 ohms measured per square, on the back became a sheet resistance measured from 240 ohms per square. These are relatively low surface resistances.

By Grounding of the surfaces Therefore, the static charge can be reduced or even canceled become.

In order to will be the desired Antistatic effect achieved.

5 shows an embodiment of the system discussed above in the introduction, consisting of two layers on the front 2 of the substrate 1 , The "first" applied to the substrate layer replaces the two-layer system 5 the reference number 17 ,

This is followed by the viewer to the "second" layer 18 ,

For the "first" shift 17 and the "second" layer 18 of the two-layer system 5 those data on the chemical compositions, the layer thicknesses, the refractive indices and those combinations of these data are used, which for the layers 5 and 6 of the 1 and 2 described above and in the introduction to the description.

The for the layers 5 and 6 in the introduction to the description and in connection with the 1 and 2 described alternative embodiments also apply to the two-layer system, as for example in 5 with the "first" layer 17 and the "second" layer 18 is pictured.

The "first" layer corresponds to this 17 of the two-layer system of 5 the layer 5 the layer systems of 1 and 2 ,

The "second" layer 18 of the two-layer system of 5 equivalent. the layer 6 the layer systems of 1 and 2 ,

The surface resistances of the two-layer system correspond to those of the systems according to 1 and 2 ,

1

substrate Glass

2

front

3

Arrow, line of sight

4

"first" layer of the 1 and 2

5

"second" layer of 1 and 2

6

"third" layer of the 1 and 2

7

Bonding layer

8th

Back layer

9

back

10

abscissa

11

left ordinate

12

right ordinate

13

transmission curve

14

reflection curve

15

transmission curve

16

reflection curve

17

"first" layer of the 5

18

"second" layer of 5

Claims (3)

Optically effective layer system for substrates, wherein the layer system has a high antireflection effect, characterized in that on the front side facing a viewer of a substrate ( 1 ) in the local order from the substrate ( 1 ) to the viewer a first on the substrate ( 1 ), forming a dielectric, metal oxide-containing layer ( 4 ) with a layer thickness of 80 Å +/- 20%, thereon a second nitride-containing layer ( 5 ) is arranged with a layer thickness of 130 Å +/- 20%, on the rear side of the substrate (1) a TiN _x layer ( 8th ) is arranged with a layer thickness of 40 to 150 Å and the substrate ( 1 ) is transparent and has a refractive index of 1.5 to 1.65. An optically acting layer system for substrates according to claim 1, characterized in that for at least one of the nitride-containing layers ( 5 . 8th ) Stoichiometric TiN _x with x in the range of 1 to 1.16 is used. An optically acting layer system for substrates according to claim 1, characterized in that for all the nitride-containing layers ( 5 . 8th ) Stoichiometric TiN _x with x in the range of 1 to 1.16 is used.