DE2750500A1 - Panes with IR reflecting properties - obtd. by sputtering on first an indium oxide-tin oxide layer, then a gold, silver or copper layer - Google Patents

Abstract

Panes which are transparent to visible light while reflecting IR are obtd. by reactive cathode sputtering of an indium oxide layer onto a substrate followed by coating with Au, Ag or Cu. A target consisting of an In alloy contg. 10-35 wt.% of Sn is sputtered in a pure O2 atmos. until a mixed oxide layer of thickness 1/100 - 1/10 of a wavelength (based on a wavelength lambda = 550 nm) is produced. A layer of Au, or Cu is then sputtered on in an inert atmos. until a layer 5-20 nm thick is obtd. Opt. another mixed oxide layer of In2O3 and SnO2 can then be applied to improve the filter properties. IR-reflecting panes are produced economically with largely uniform coatings.

Description

"Process for the production of infrared reflecting,

Panes largely transparent to visible light and through the method manufactured disc The invention relates to a method for the production of infrared-reflecting, largely transparent for visible light Discs by coating a substrate with indium oxide by sputtering in an oxidizing or inert gas atmosphere and subsequent coating with a Metal from the group gold, silver and copper.

Windows for buildings and motor vehicles with infrared reflecting Properties have become known in large numbers.

In general, these are substrates made of transparent material, in addition to window glass, hard glass, laminated glass and plastics such as primarily Acrylic glass include those with a layer of a metal from the group gold, silver and copper are coated. In almost all cases it will be additional between the substrate and the metal layer still have a layer of one of the known adhesion promoters such as nickel and / or chromium and optionally also in addition one or more dielectric layers, which have the reflective properties and should have a favorable effect on the color appearance. After all, it is the same known to protect the layer or layer combination from a top layer a resistant dielectric or an attached glass pane.

A large number of Process has become known, which is partly based on the principles of vacuum evaporation, of cathode sputtering, but also to some extent of galvanic deposition do. Most of the disks made by the known methods have useful infrared reflective properties, i.e. they allow light to pass through the visible spectral range largely through, but reflect the largest part the infrared radiation. However, problems still exist in terms of an economic one Manufacture and durability of such discs.

GB-PS 769 697 describes a process for the production of transparent ones Discs known in particular for use in aircraft and motor vehicles, in which a layer of indium oxide is first applied to the transparent substrate will. The application can, among other things, by cathode sputtering of indium oxide or by vacuum evaporation and sputtering of indium, which subsequently by heating in air or by a glow charge is oxidized. A thin gold layer is then placed on top of the indium oxide layer Applied in a thickness between 25 and 32 R, either by vacuum deposition or by cathode sputtering. The optical transmission of the entire layer should between 69 and 75X. Apart from that the thickness of the gold layer is not sufficient for an effective reflection of the thermal radiation in the infrared range, the previously known layer is also essentially intended to produce a noticeable to have electrical conductivity with good transparency. However, it has shown that neither the known order of the layers, nor the intended Manufacturing process an economical manufacture of infrared reflecting panes if one were to transfer the known procedure to it.

Today the market demands window panes in the size 3 x 4, which should be coated uniformly.

The cathode sputtering process is generally used for such large panes preferred because it is difficult and cumbersome, using numerous, all in one so-called evaporator field arranged evaporator a sufficiently uniform To generate precipitation rate. The reason for this is in the need for one to see extremely precise charging and control of the individual evaporators.

The sputtering process is particularly suitable for Pollination of areas that are many times larger than the cathode or Target area. In this case there is a relative movement between the cathode and the substrate through so that the entire substrate surface is coated one after the other. You can either choose a relatively low speed of movement and coat the substrate in one pass, or multiple passes if For example, the substrate, which inevitably occurs during cathode sputtering Heat load not tolerated. The duration of a coating process under execution a relative movement is a multiple of the duration of a so-called static movement Coating in which the target and substrate are arranged in a fixed position opposite one another are. The multiple results from the quotient substrate length / target width, in each case seen in the direction of movement.

In other words, the substrate is 10 times wider than the target, this results in a coating tent that is about 10 times longer than one static coating.

In this case, however, very uniform coatings are obtained because of irregularities of the atomization process are compensated in the time average and there in particular the so-called edge effects cannot appear.

When reactively pollinating large areas in an atmosphere that does not consists exclusively of the reaction gas, one must local depletion of the gas mixture avoid with regard to the actual reaction gas. This requires large gas throughputs and thus very high pumping speeds required for the coating system Vacuum pumps. The theoretically required suction capacities of the vacuum pumps are partly outside of reasonable investment costs.

For the production of oxide layers by cathode sputtering will therefore either such metallic target materials are preferred which are tn a retnen oxygen atmosphere atomize, so that depletion of the reactive gas does not appear and relatively small vacuum pump sets are sufficient are, or corresponding oxidic targets that are in an inert gas atmosphere let it atomize effectively.

The invention is therefore based on the object of providing a method of Specify the type described at the beginning, with which an economical production of infrared reflecting panes possible with large glaciers is.

The problem is solved according to the invention by that one has a target made of an indium alloy with 10 to 35 percent by weight tin dusted in a pure oxygen atmosphere until a mixed oxide layer with a layer thickness from 1/100 to 1/10 wavelength, based on measuring light with a wavelength of h - 550 nu, and that the metal from group 601d, silver, Sputter copper under inert gas until a layer thickness of 5 to 20 nm is present is. An indium alloy with 20 percent by weight tin is preferably used.

Under the usual atomization conditions at 10 2 to 10 -1 mbar and the usual discharge currents and voltages can be used with such Target and with a required layer thickness of 1/20 wavelength static dusting times of about 15 seconds, being under "static" it is to be understood that there is no relative movement between target and substrate. Also the dusting times under inert gas for the relatively thin layer of gold, Silver or copper are only a few seconds. Static pollinations are used in the generally carried out for experimental purposes on substrates with a smaller area. As already explained above, the times found can be easily transferred to large-area substrates in which a relative movement is carried out between substrate and target. The substrate has a 10-fold linear expansion like the target (in the direction of movement) so is the one found by static experiments Time to multiply by a factor of 10. Dles means that with a 4 m long Substrate (window pane) and a 0.4 m wide target made of the indium alloy or the oxide mixture in question, about 150 seconds for the application of a mixed oxide layer with a layer thickness of jt / 20 are completely sufficient.

An alternative method for solving the problem is according to of the further invention, characterized in that a target is made from a mixture of In203 and SnO2 in a weight ratio of about 3: 1 to 9: 1, to a mixed oxide layer with a layer thickness of 1/100 to 1/10 wavelength on measuring light with a wavelength,) t = 550 nm, is present, and that one then the metal from the group of gold, silver and copper is sputtered under inert gas until a layer thickness of 5 to 20 nm is also present.

When atomizing an Oxtdt target in an inert gas atmosphere the pollination tents can be placed on about 1/3 to 1/4 of the pollination tents reduce that when using a metal target made of the specified alloy are needed. So if one strives for layers with a thickness of x f10, then arbettet one expediently with oxidic targets; if you want layers with a thickness of> / 100 work with metallic targets is sufficient.

The noticeable increase in the profitability of the two alternatives Process is specially designed to reduce the layer thickness of the individual layers to be returned; Nevertheless, layer properties were surprisingly achieved, with the teaching according to the invention in contrast to that regularly found in the literature It is stated that the thickness of the oxide or dielectric layer must be one The quarter wavelength of the measuring light used correspond to (Dt-AS 21 38 517).

Embodiments of the invention and an excerpt from one Windows manufactured according to the invention for a vehicle or a building are given below explained in more detail with reference to FIGS. 1 to 3.

The figures show: FIG. 1 a section of a window pane with a triple layer according to the invention, Figure 2 is a diagram of the spectral Dependency of the transmission behavior of one described in more detail below Double layer according to Example 1 and FIG. 3 shows a diagram of the spectral dependence of the transmission behavior of a triple layer of mixed oxide-metal-oxide according to Example 3 (upper curve) in comparison to the spectral transmission behavior of a pure metal layer of gold (lower curve) of the same thickness.

In Figure 1, a substrate S made of normal window glass is shown, on which first a first layer 1 made of the mixed oxide according to the invention was knocked down. This is followed by a second layer 2 from one of the specified metals gold, silver or copper, on which a third layer 3 in turn was applied from mixed oxide according to the invention. Have layers 1, 2 and 3 each have a thickness which lies within the ranges specified in the claims. The transmission behavior of such a layer combination is shown in FIG. 3, top Curve.

The other figures are explained in connection with the examples.

Example 1: In a cathode sputtering system with a cylindrical Vacuum chambers of 5.80 m in length and 3.70 m in diameter were provided with two panes of glass the dimensions 2.65 mx 4.0 m each other arranged opposite. Between The glass panes had a target that could be moved in the horizontal direction 2.90 m high and 0.40 m wide, which is made of an alloy of 80 percent by weight Indtum and 20 percent by weight tin.

After charging, the system was brought to a pressure of 10 5 mbar evacuated. Thereafter oxygen was let in until a pressure of 4 x 1012 mbar was reached. The cathode sputtering was then carried out by means of a direct voltage started from 1.9 to 2 kV. The target was moved at such a speed that the single pass was completed within 150 seconds, i.e., pollination lasted 150 seconds. With the specified ratio of substrate length to target board the result is a factor of 10, i.e. the static pollination of a corresponding smaller substrate would have taken 15 seconds. Those through the pollination process The indium-tin mixed oxide layer produced has a thickness of 1/100 wavelength. Thereafter the system was again evacuated to a pressure of 10 5 mbar and then Argon admitted up to a pressure of 4 × 10 2 mbar. After this pressure is reached was a gold target measuring 2.90 x 0.20 m under a DC voltage of 2 kV moves over the substrate at such a speed that the coating process completed after 180 seconds. The resulting gold layer had a Thickness of 8 nm.

The transmission behavior of a under the above conditions produced layer is shown in Figure 2, using a curve which the transmission in down dependence on the wavelength of the measuring light which was changed between 400 and 1,100 nm, It can be seen that the layer system has good filter properties despite the small thickness of all individual layers owns.

Example 2: In the system according to Example 1, the metallic target by an oxidic target of the same size made of 80 mol percent In203 and 20 mol percent Replaces SnO2. The number and dimensions of the substrates remained the same. Thereafter the system was evacuated to a pressure of 2 × 1016 mbar and then Argon let in until the pressure was 5 × 1012 mbar. Then there was the atomization Over a period of 280 seconds at a DC voltage of 2.5 to 2.6 kilovolts carried out with continuous relative movement of the target with respect to the substrate. The thickness of the oxide mixture layer was here 1/20 wavelength, i.e. although the Layer thickness was 5 times as great as in Example 1, the coating time was only 186 times, i.e. the atomization rate was approx. 2.7 times as high as when it was used of a metallic target in Example 1.

Subsequently, the system was again to a pressure of 2 x 10 mbar evacuated and then argon let in until a pressure of 5 x 10 2 mbar was reached. Then the gold target already used in Example 1 became for a period of 290 seconds at a DC voltage of 1.4 kilovolts atomized. The resulting beaten gold layer possessed a thickness of 13 nm.

Example 3: The products made by Example 2 were by applying the third layer of the mixed oxide to form a 3-layer system according to Figure 1 added. For this purpose, the system was again down to a pressure of 2 x 10-6 mbar evacuated and then argon let in until a pressure of 5 x 10 2 mbar was reached. This was followed by the atomization of the Oxtd target Uber a period of 280 seconds at a DC voltage of 2.5 to 2.6 kilovolts carried out. As a result of the consistency of the atomization conditions was also here the thickness of the oxide mixture layer 1/20 wavelength.

The transmission behavior of this triple layer is shown in FIG. 3 graphically represented (upper curve This shows that despite the relatively Thin individual layers could be achieved in terms of properties the requirements described above are fully satisfactory. The layer properties do not differ significantly from the layer properties of such layer systems, which have been produced with much more complex processes.

Example 4 (comparative example): The procedure of Example 1 was repeated, but with the difference that the precipitation of the oxide mixture layer was continued until a layer thickness of a quarter wavelength was reached. If this process is to be economically feasible, it must be through a high Discharge current a large atomization rate can be achieved. With a specific Discharge power of 4 watts / cm2 caused glass breakage due to excessive heat load. When the discharge power was reduced to 3.3 watts / cm2, the result was flawless Layers, however, a period of 60 minutes is required for each oxide layer required, so that the procedure is ruled out for practice.

Example 5 (comparative example): The experiment with an oxidic Target according to Example 2 was repeated, but also with the difference that the sputtering of this target was continued until a quarter wavelength layer was achieved.

Despite the high specific discharge power of 4 watts / cm2 15 minutes are required for each oxide layer, so that this procedure is also practical Application ruled out.

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Claims (5)

A N 5 P R 0 C H E: 1.1 Process for the production of infrared reflective, for panes that are largely transparent to visible light by coating a Substrate5 by reactive cathode sputtering with indium oxide and subsequent coating with a metal from the group gold, silver, copper, characterized in that a target made of an indium alloy with 10 to 35 percent by weight tin in pure oxygen atmosphere until a mixed oxide layer with a layer thickness from 1/100 to 1/10 wavelength, based on measuring light with a wavelength jk = 550 nm, and that the metal from the group gold, Silver, copper is sputtered under inert gas until a layer thickness of 5 to 20 nm is present is. 2. Process for the production of infrared reflective, for visible Light largely transparent panes by coating a substrate through Cathode sputtering with indium oxide and subsequent coating with a metal from the group gold, silver, copper, characterized in that one has a target from a mixture of Ion203 and SnO2 in a weight ratio of about 3: 1 to 9 : 1 dusting until a mixed oxide layer with a layer thickness of 1/100 to 1/10 Wavelength, based on measuring light with a wavelength of 22 = 550 nm, and that you then remove the metal the group gold, silver, Copper is sputtered under inert gas until a layer thickness of 5 to 20 nm is present is. 3. The method according to claim 1 or 2, characterized in that for Improvement of the filter properties on the layer made of a metal from the group Gold, silver, copper and another mixed oxide layer made of Ion203 and Sn02 a layer thickness of 1/100 to 1/10 wavelength is applied, with either a metallic target made of an indium alloy at 10 to 35 percent by weight Tin in an oxidizing atmosphere or an -oxidic target made of In203 and Sn02 im Ratio of 3: 1 to 9: 1 is atomized in an inert gas atmosphere. 4. Disc for vehicles and buildings, marked with a transparent one Substrate (S) with a first layer (1) made of a mixed oxide of In203 and SnO2 in a ratio of 3: 1 to 9: 1 with a layer thickness between / 100 and h / 10 on measuring light with a wavelength λ = 550 nm and through a second layer (2) from a metal from the group gold, silver, copper with a layer thickness of 5 to 20 nm. 5. Disc according to claim 4, characterized by a third layer (3) from a mixed oxide of In203 and Sn02 in a ratio of 3: 1 to 9: 1 with a Layer thickness between / 100 and A / 10, based on measuring light with one wavelength ; t = = 550 nm.