JPH0524987B2 - - Google Patents

Description

[Detailed description of the invention]

The invention relates to a transparent substrate of glass or plastic coated with a low emissivity coating, in particular a transparent substrate coated with a low emissivity silver coating having a silver layer and an anti-reflective oxide layer of a metal oxide thereon; The present invention relates to a method of manufacturing such a coated substrate by cathode sputtering. Low emissivity silver coatings are known and described in the prior art, for example in GB 1307642. This specification describes a conductive glass article consisting of a glass substrate and a conductive coating, each with a thickness of 70 mm, an anti-reflective layer to provide an electrical resistance of less than 3 ohms/sq.
A 200-300 Å thick interlayer of 50% or more silver placed between a pair of ~550 angstrom layers of non-absorbing dielectric material has been used to increase the optical transmission of the coated glass. This specification proposes incorporating up to 10% chromium, nickel, aluminum or titanium, or up to 50% copper into the silver layer; the use of copper is, according to this specification, substantially It is said that it gives a gray transparency that cannot be easily obtained with films made of silver. It is said that silver or metal oxide deposition can be carried out by cathodic sputtering. To form a silver layer incorporating additional metals, a silver alloy is deposited or multiple metal elements are deposited simultaneously under vacuum. U.S. Pat. No. 4,166,876 describes a coating having one metal layer, such as silver, gold, copper, platinum or tin, sandwiched between two titanium oxide layers on a plastic substrate. ing. This patent teaches that if the underlying titanium oxide layer is derived from an organotitanium compound and contains residual organic moieties, bonding to the resin substrate is significantly improved along with improved clarity of the laminate structure. are doing. This specification specifies that the copper-containing silver layer can be vacuum evaporated, although the silver layer can contain 1-30% copper which reduces the tendency of the coating to degrade and can cause it to gradually lose its light reflective properties with prolonged exposure. teaches that silver-copper alloys can be deposited by. European Patent No. 0035906 describes a coating in which one silver layer is sandwiched between two metal oxide layers. The metal oxide layer can be deposited by sputtering, ion plating, or vacuum evaporation, or from solution. The patent states that to improve the long-term durability of the coating, a thin layer of a material selected from the group consisting of titanium, zirconium, silicon, indium, carbon, cobalt and nickel is combined with a silver layer and an overlying metal oxide. It teaches that it is necessary to deposit between layers. This specification teaches that, as far as possible, the material should be deposited under conditions that do not convert it to oxides, and that when depositing the overlying metal oxide layer by sputtering, Sputtering is carried out using an oxide source under an argon atmosphere,
This avoids oxidation of the substance as much as possible. A silver coating consisting of a silver layer sandwiched between anti-reflective metal oxide layers as described above not only has high conductivity but also low emissivity. That is, such a silver coating reflects most of the incoming infrared radiation, but transmits shortwave infrared radiation and visible radiation. The use of such coatings on window glass (or plastics used in place of glass) reduces heat loss through the window, which is increasingly desirable to reduce heating costs as energy costs rise. I'm getting used to it. Unfortunately, when attempting to produce a coating consisting of a metal oxide layer on top of a silver layer by reactive sputtering in the presence of oxygen, the low emissivity nature of the silver layer is lost. , it was found that the light transmittance of the product was significantly lower than expected. This difficulty can be overcome by sputtering a small amount of a metal other than the silver before the metal oxide layer, such that the additional metal is preferentially on or in the top of the silver layer. This problem can be solved by invention. The present invention provides a method for producing a transparent substrate of glass or plastic coated with a low-emissivity coating by cathode sputtering, in which step: (i) a transparent substrate of glass or plastic is coated with a 5-30 nm thick layer of silver; (ii) sputtering on top of this silver layer one or more additional metals other than silver in an amount corresponding to a 0.5-10 nm thick layer; (iii) said additional metals; 1 in the presence of oxygen or an oxidizing gas over the layer of silver and the additional metal under conditions that would otherwise result in a significant loss of the low emissivity properties of the coating that would form on the substrate. A method for producing a transparent substrate coated with a low emissivity coating is provided, the method comprising reactively sputtering one or more anti-reflective metal oxide layers. Therefore, the use of additional metals in the present invention makes it possible to deposit one or more metals onto the silver layer under conditions where the high light transmission and low emissivity properties of the product would be significantly lost if the additional metals were not sputtered. Enables reactive sputtering of anti-reflective metal oxide layers. The method of the invention makes it possible to produce coatings with an emissivity of less than 0.2 and a light transmittance of more than 70% in an effective and economical manner. The present invention further provides a silver-coated glass or plastic product having an emissivity of less than 0.2 and a light transmittance of greater than 70% coated in accordance with the present invention. The substrate is conveniently a window glass, and the preferred product has an emissivity of less than 0.1 and a light transmittance of more than 75%, preferably
80% or more. Sputtering a small amount of one or more other metals after the silver prevents the dramatic increase in emissivity and decrease in light transmission, which would otherwise be resisted by reactive sputtering. It has been found that an increase in emissivity and a decrease in light transmittance occur when depositing a reflective metal oxide layer. Moreover, once sufficient additional metal is deposited to prevent an increase in emissivity and an associated substantial loss of optical transmission, the optical transmission of the coating is reduced by the deposition of such additional metal. do. It is generally desirable to keep the light transmittance of the coating as high as possible, and therefore one or more of just enough to obtain a coating with the maximum possible light transmittance while at the same time maintaining the emissivity of the coating at a value of 0.1. Preferably, additional metals are used. The exact amount of additional metal required to provide the desired optimum combination of emissivity and optical transmittance will vary with deposition conditions, but the amount of additional metal and the underlying silver layer or overlying oxide may vary with deposition conditions. 0.5~10n assuming no interdiffusion with layers
The quantity should be sufficient to provide a metal layer of m thickness, preferably 1 to 5 nm thick. In a particular case, the optimal amount of additional metal to be used can be determined by a simple test as described below. Of course, any additional metals must be suitable for sputtering, with a melting point of 50°C or higher,
It must be stable in air and conductive.
Preferred metals are generally transition metals and periodic table 3a
-Group 5a metals (described on page B-3 of the Handbook of Chemistry and Physics (Plate 50), published by The Chemical Rubber Company, Cleveland, Ohio, USA) (such as metals), but other metals that are stable in air, melt above 50°C, and conductive can be used if desired. In particular, as an additional metal, during the reactive sputtering of the overlying anti-reflective metal oxide layer, a metal oxide, preferably a colorless metal oxide (i.e. a metal that does not absorb light in the visible part of the spectrum) is oxidized. Good results are obtained with oxides such as aluminum, titanium and zirconium. When using a metal that oxidizes to a colorless metal oxide,
Even if the amount of this metal is increased, colored metal,
The light transmission of the product is less affected than, for example, with copper and gold, which are less easily oxidized. The tendency of metals to form oxides depends on the free energy of metal oxide formation. Apart from the surprisingly good results obtained using copper, which is not easily oxidized, the oxide is
-100,000 calories per gram mole (for values of the standard free energy of oxide formation, see, e.g., Addison-Wesley Publishing Company, Inc., John F.
``Thermochemistry for Stellmaking'' by Eliot and Mori Gleisser
The best results have been obtained using metals that are more negative (see Figure 3.3 of Volume 1, 1960). However, even when using metals such as titanium, which oxidizes to colorless metal oxides, metal layers less than 5 nm thick (including the silver layer and For the anti-reflective metal oxide layer, it is generally preferred to use a sufficient amount of metal to provide an anti-reflective metal oxide layer (assuming no oxidation and interdiffusion of the metal). Other examples of preferred metals include bismuth, indium, lead, manganese, iron, chromium, nickel, cobalt, molybdenum, tungsten, platinum, gold, vanadium and tantalum and alloys of these metals, such as stainless steel (Fe/Cr /
Ni) and brass (Cu/Zn). A sufficient amount of silver is deposited to give a layer thickness of 5-30 nm. Generally, the thicker the silver layer, the lower the emissivity, but also the lower the total light transmittance. 20nm
Larger thicknesses are generally only needed for conductive applications and low emissivity coatings, generally using silver layers less than 20 nm thick, preferably 8-15 nm thick. The anti-reflection metal oxide layer on the silver layer preferably consists of a metal oxide with low absorption of visible light, such as tin oxide, titanium oxide, zinc oxide, indium oxide, indium oxide (doped with tin oxide), It can be composed of bismuth oxide or zirconium oxide. Tin oxide, titanium oxide, indium oxide, indium oxide doped with tin oxide, bismuth oxide and zirconium oxide are preferred. The reason for this is that, besides the anti-reflective properties they provide, they serve to provide a silver layer with good durability and some protection from mechanical damage. The thickness of the anti-reflection layer used depends on the particular metal oxide used and the desired product color, but is usually in the range 10-80 nm, especially 20-60 nm. If desired, instead of using a single metal oxide layer, two or more layers of different metal oxides may be applied sequentially to achieve a similar overall thickness, i.e.
Usually it can be between 10 and 80 nm, especially between 20 and 60 nm. If desired, an anti-reflective layer can be sputtered onto the glass before the silver layer to increase the light transmission of the product. If the anti-reflective layer is deposited below the silver layer, this anti-reflective layer is advantageously a metal oxide layer, for example one of the metal oxides mentioned above for use as an anti-reflective layer on the silver layer. be. This underlayer acts not only as an anti-reflection layer but also as a primer layer to improve the adhesion of the silver layer to the glass. Usually the thickness is 10-80nm, especially 20-60n
m, but in the particular case the thickness used will depend on the metal oxide chosen and the color and other properties desired in the product. If desired, two or more anti-reflective layers may be sequentially provided under the silver layer so that the overall thickness of the anti-reflective layer is the same, i.e., typically 10 to 80 nm.
m, especially from 20 to 60 nm. In a preferred embodiment, the present invention provides a method of cathodic sputtering a glass transparent substrate coated with a low emissivity coating, the method comprising: (a) depositing an oxygen or oxidizing gas on the glass substrate; 30 by reactive sputtering of tin in the presence of
Depositing an anti-reflection layer of SnO ₂ ~50 nm thick; (b) sputtering a 8-12 nm thick silver layer on top of the anti-reflection layer; (c) sputtering a 1-5 nm thick layer on top of the silver layer. sputtering an amount of copper corresponding to one layer of copper; then (d) depositing on the coating thus formed;
A 30-50 nm thick anti-reflection layer of _SnO2 is deposited by reactive sputtering of tin in the presence of oxygen or oxidizing gas. It is not known how additional metal deposited after the silver layer prevents the properties of the coating from deteriorating. One possibility is that the additional metal has the effect of preventing oxidation of the silver when reactively sputtering the overlying anti-reflective metal oxide layer, or alternatively, Under the oxidizing conditions used for deposition, silver tends to agglomerate, resulting in a discontinuous silver layer, and it is believed that additional metals present at the surface of the silver layer counteract this tendency. However, it is not clear what corresponding measures need to be taken to prevent the silver from being attacked by oxygen in the underlying anti-reflective metal oxide layer. The sputtering process can be magnetically enhanced to increase production yields, and the method of the invention
It is particularly advantageous in processes in which metal and metal oxide layers are deposited by magnetically enhanced sputtering. Such magnetically enhanced sputters are generally more demanding and appear to cause degradation of the silver layer than in non-magnetically enhanced sputter processes. Auger electron spectroscopy testing of coatings produced by the method of the invention shows that the additional metal is concentrated on top of the silver layer, rather than being deposited as a separate layer on top of the silver layer. It has been found that it can be dispersed throughout the silver layer and spread over the top surface of the silver layer. In some cases this may be combined with additional oxygen, ie present, at least in part, as a metal oxide. Thus, according to yet another aspect of the invention, in a transparent substrate of glass or plastic coated with a low-emissivity coating, on the transparent substrate there is provided, in sequence: (a) a 5-30 nm thick layer of silver; b) The total amount corresponds to a metal layer with a thickness of 0.5 to 10 nm.
one or more additional metals that are non-uniformly dispersed in the silver layer, with the concentration of the additional metal in the silver layer being at a maximum in the upper half of the silver layer; (c) providing a transparent substrate coated with a low emissivity coating, characterized in that the low emissivity coating comprises an anti-reflective metal oxide layer; In a preferred embodiment, a glass substrate coated with a low emissivity coating of the present invention comprises:
Sequentially: (a) a 30-50 nm thick anti-reflection layer of SnO ₂ , (b) an 8-12 nm thick layer of silver, (c) a 1-5 nm thick copper layer with sufficient copper to give (d) anti-reflection of SnO ₂ with a thickness of 30-50 nm; It has a low emissivity coating consisting of layers. In products with particularly good emissivity and light transmission properties, the additional metal or metals are not completely dispersed in the silver layer, but are spread over the entire upper surface of the silver layer. It's stiff. In some cases, the one or more additional metals are present, at least in part, as metal oxides. The light transmittance values shown herein are the light transmittance values from the C.I.I. Illuminant Sea Source. The emissivity values shown here were obtained by applying the following equation. Emissivity ε=∫∽／ ₀ eλB(λ, T) dλ／∫∽／ ₀ B(λ
, T) dλ In the above equation, eλ=spectral radiation power B(λ, T)=energy distribution of black body spectrum at 300〓 Below, the present invention will be described with reference to embodiments. Example 1 A piece of float glass 4 mm thick was prepared for coating by cleaning and drying,
It was mounted on an in-line DC planar magnetron sputter device. Tin oxide (SnO ₂ ) was reactively sputtered onto the glass surface from a tin cathode in the presence of an oxygen atmosphere at 2.5×10 ⁻³ Torr (3.4×10 ⁻³ g/cm ² ) to form a 40 n
A tin oxide layer of m thickness was provided. Then 3.0×
10 nm thick from a silver cathode onto tin oxide in the presence of an argon atmosphere at 10 ^-3 torr (4.1 x 10 ^-3 g/cm ² ).
A silver layer of m was sputtered. Furthermore, 2.5×10 ^-3
A 40 nm thick layer of tin oxide was reactively sputtered onto the silver layer from a tin cathode in the presence of an oxygen atmosphere at Torr (3.4×10 ⁻³ g/cm ² ). The light transmittance of the product was 55% and the emissivity was 0.9. In accordance with the present invention, immediately after sputtering the silver layer, a 1.6 nm thick layer is deposited from a copper cathode onto the silver layer in the presence of argon at 3.0 x 10 ^-3 Torr (4.1 x 10 ^-3 g/cm ² ).
The above procedure was repeated, except that an amount of copper was sputtered corresponding to the copper layer. Then, immediately after the copper, 2.5×
A second tin oxide layer was reactively sputtered from a tin cathode in the presence of an oxygen atmosphere at 10 ^-3 Torr (3.4 x 10 ^-3 g/cm ² ). In this case, the light transmission of the product was 79%. The emissivity of the coated product is
It was 0.06. The influence of copper in producing low emissivity products with high light transmission is clear. The copper-contaminated product was analyzed by Auger electron spectroscopy, and the results are shown in FIG. In Auger analysis, an electron beam (main beam) is directed at the surface to be analyzed, and the energy spectrum of secondary electrons emitted from the surface is examined.
The characteristics of the elements present on the surface were determined and quantified. The surface atomic layer was then removed by argon ion etching to expose the sub-surface atoms, which were then characterized and quantified as described above. The etching and analysis steps were repeated to create the compositional distribution of the surface layer to the desired depth (in this case, the thickness of the coating). The sputter time or ion etch time, plotted along the There is no linear relationship with depth. The concentration of removed material, in atomic %, is plotted on the X-axis. At the surface of the coating (ie when etching removal begins), the composition of the coating corresponds substantially to SnO ₂ . The spectrum is
The central large peak indicates the silver layer, and the significantly lower peak within the silver peak indicates copper dispersed in the silver layer. It can also be seen that the maximum concentration of copper, about 20 at.%, occurs after 80 seconds and is within the top half of the silver layer. Moreover, a small amount of copper is clearly on top of the silver layer, ie, copper is detected after 55 seconds, but silver is not detected until after 65 seconds. It is desirable to have a small amount of copper on top of the silver layer, which improves properties. about 95
After seconds, the removed material is mainly _SnO2 .
After about 150 seconds, some silicon is detected, but
This is probably obtained from the glass surface. There is considerable overlap in the various materials used in the processes described above. This is likely a result of ion diffusion in the coating, but since the sample is prepared in an in-line sputtering device and adjacent cathodes are activated simultaneously, some overlap in deposition may occur. Example 2 The procedure described above including copper deposition was repeated using the same sputtering times and conditions as described above, but varying the amount of copper deposited. When sputtering an amount of copper equivalent to a 3.2 nm thick copper layer, the final product had a light transmission of 75% and an emissivity of 0.16.
When sputtering an amount of copper equivalent to a 1.0 nm thick copper layer, the light transmission of the product is 79%;
The emissivity was 0.12. Example 3 A piece of float glass 4 mm thick was prepared for coating by cleaning and drying,
It was mounted on an in-line DC planar magnetron sputter device. A 30 nm thick layer of tin oxide was deposited by reactively sputtering tin oxide onto the glass surface from a tin cathode in the presence of an oxygen atmosphere at 2.5×10 ⁻³ Torr (3.4×10 ⁻³ g/cm ² ). gave. Zinc oxide was then reactively sputtered onto the tin oxide layer in the presence of an oxygen atmosphere at 2.5 x 10 ^-3 Torr (3.4 x 10 ^-3 g/cm ² ) to form a 15 nm thick layer of zinc oxide. gave. Then,
from a silver cathode onto the zinc oxide layer in the presence of an argon atmosphere at 3.0×10 ⁻³ Torr (4.1×10 ⁻³ g/cm ² ).
A 10 nm thick silver layer was sputtered onto the 3.2 nm thick copper layer from a copper cathode in the presence of argon at 2.5 x 10 ^-3 Torr (3.4 x 10 ^-3 g/cm ² ). A corresponding amount of copper was sputtered. Finally, each 15nm
thick and 30 nm thick zinc oxide and tin oxide layers in that order at 2.5 × 10 ^-3 Torr (3.4 × 10 ^-3
g/cm ² ) from the metal cathode onto the copper in the presence of an oxygen atmosphere. The resulting coating product has an emissivity of 0.08 and a light transmittance of
It was 80%. Example 4 A piece of float glass 4 mm thick was prepared for coating by cleaning and drying,
It was mounted on an in-line DC planar magnetron sputter device. 90% by weight indium and 10% by weight in the presence of oxygen atmosphere at 2.5×10 ^-3 Torr (3.4×10 ^-3 g/cm ² )
By reactively sputtering tin and indium onto the glass surface from a cathode made of tin,
A thick tin oxide doped indium oxide layer was provided. Then 3.0×10 ^-3 torr (4.1×10 ^-3 g/cm ² )
A 10 nm thick layer of indium oxide doped with tin oxide was deposited from a silver cathode in the presence of an argon atmosphere at
m silver layer and 3.0×10 ^-3 Torr (4.1×
Copper was sputtered onto the silver layer from a copper cathode in the presence of argon at 10 ^-3 g/cm ² ) in an amount corresponding to a 3.2 nm thick copper layer. Finally, 30nm similar to the first layer
A second anti-reflective layer of a thickness of tin oxide doped indium oxide was reactively sputtered onto the copper. The resulting coated product has an emissivity of 0.1 and
The light transmittance was 74%. Example 5 A piece of float glass 4 mm thick was prepared for coating by washing and drying,
It was placed on an in-line DC planar magnetron sputter device. A 40 nm thick layer of tin oxide was deposited by reactively sputtering tin oxide onto the glass surface from a tin cathode in the presence of an oxygen atmosphere at 2.5 × 10 ^-3 Torr (3.4 × 10 ^-3 g/cm ² ). gave. Titanium oxide was then reactively sputtered onto the tin oxide layer in the presence of an oxidizing atmosphere at 2.5 x 10 ^-3 Torr (3.4 x 10 ^-3 g/cm ² ) to form a 10 nm thick layer of titanium oxide. Gave. A 10 nm thick layer of silver was then sputtered onto the titanium oxide layer from a silver cathode in the presence of an argon atmosphere at 3.0 x 10 ^-3 Torr (4.1 x 10 ^{-3 g} /cm ² ). An amount of copper corresponding to a 3.2 nm thick copper layer was sputtered from a copper cathode onto the silver layer in the presence of argon at Torr (4.1×10 ⁻³ g/cm ² ). Finally, each
10 nm thick and 40 nm thick titanium oxide and tin oxide layers at 2.5 x 10 ^-3 torr (3.4 x 10 ^-3 g/
cm ² ) in the presence of an oxygen atmosphere from the metal cathode onto the copper. The resulting coated product has an emissivity of 0.15 and a light transmission of 80%
It was hot. Example 6 A piece of float glass 4 mm thick was prepared for coating by washing and drying,
It was mounted on an in-line DC planar magnetron sputter device. from a titanium cathode onto a glass surface in the presence of an oxygen atmosphere at 2.5×10 ⁻³ Torr (3.4×10 ⁻³ g/cm ² ).
Titanium oxide was reactively sputtered to provide a 15 nm thick layer of titanium oxide. Then 2.5×10 ^-3
Tin oxide was reactively sputtered onto the titanium oxide layer in the presence of an oxygen atmosphere at Torr (3.4×10 ^-3 g/cm ² ). Then, a 10 nm thick silver layer was applied to 3.0×
Sputtering from a silver cathode onto the tin oxide layer in the presence of an argon atmosphere at 10 ^-3 Torr (4.1 x 10 ^-3 g/cm ² ) and 3.0 x 10 ^-3 Torr (4.1 x 10 ^-3 g/cm ^{2 )} ) on the silver layer from the tin cathode in the presence of argon.
An amount of tin corresponding to the thickness of the tin layer was sputtered. Finally, a tin oxide layer and a titanium oxide layer with a thickness of 40 nm and 15 nm, respectively, were deposited at 2.5×
The tin layer was sequentially reactively sputtered from a metal cathode in the presence of an oxidizing atmosphere at 10 ^-3 Torr (3.4 x 10 ^-3 g/cm ² ). The resulting coated product had an emissivity of 0.16 and a light transmittance of 76%. Examples 7-22 A piece of float glass 4 mm thick was prepared for coating by washing and drying,
It was mounted on an in-line DC planar magnetron sputter device. Tin oxide was reactively sputtered onto the glass surface from a tin cathode in the presence of an atmosphere of 20% argon/80% oxygen at a pressure of 6×10 ⁻³ Torr (8.16×10 ⁻³ g/cm ² ). , giving a 40 nm thick tin oxide layer.
A 10 nm thick layer of silver was then sputtered onto the tin oxide layer from a silver cathode in the presence of an argon atmosphere at 6 x 10 ^-3 Torr (8.16 x 10 ^{-3 g} /cm ² ).
An amount of stainless steel corresponding to a 3.5 nm thick layer was deposited on the silver layer from a cathode of 316 stainless steel (an alloy of chromium, nickel and iron) under an argon atmosphere at Torr (8.16 × 10 ^-3 g/cm ² ). Sputtered steel. Finally, a layer of tin oxide is reactively deposited onto the glass surface from a tin cathode in the presence of a 20%/80% oxygen atmosphere at a pressure of 6×10 ⁻³ Torr (8.16×10 ⁻³ g/cm ² ). I sputtered. The resulting coated product has an emissivity of 0.15
The light transmittance was 80%. The above procedure was repeated using the same conditions except that various metal cathodes were used in place of the stainless steel cathode. In both cases, the use of additional metals resulted in products that maintained low emissivity and light transmission. These results are shown in the table below.

[Table] Figures 2 and 3 are Example 8 and Figure 3, respectively.
Shows the Augier spectra obtained when analyzing 10 products. These were obtained similarly to the spectra shown in Figure 1, but using a more gradual etch to remove the coating. From FIG. 2, it was found that the composition substantially corresponded to SnO ₂ on the coating surface. The spectrum shows a main silver peak in the center and a significantly lower peak representing titanium to the left of the silver peak. However, although both titanium and silver are detected after the same etching or sputtering time of 200 seconds, the titanium peak rises faster than the silver peak, indicating that the mixture of silver, titanium, and tin initially reacts more with titanium than with silver. Rich, but exactly 250
This suggests that it becomes richer in silver than titanium after etching times exceeding seconds. Therefore, the titanium is distributed non-uniformly in the silver layer, and the titanium concentration in the silver layer is maximum at the top of the silver layer. Also, the oxygen concentration never drops below about 30%, suggesting that the titanium exists as titanium oxide (probably titanium dioxide). After approximately 320 seconds, nearly all of the titanium has been removed and the composition of the coating is primarily tin oxide, although a significant portion of silver (approximately 20 atomic percent) remains. If etching continues, the silver concentration will drop to zero in about 380 seconds. The remainder of the coating corresponds substantially to SnO ₂ until elements from the glass surface are detected after an etching time of approximately 500 seconds. Figure 3 is similar to Figure 2, but in Figure 3, additional metal (aluminum) is detected before the silver metal at an etch time of 120 seconds. Silver is 150
It is first detected after an etching time of seconds, shortly before the aluminum concentration reaches its peak. Both silver and aluminum are detected by an etch time of 270 seconds, but after about 230 seconds the coating consists primarily of tin oxide. The oxygen concentration shows a small peak corresponding to the peak of the aluminum concentration, dropping to a minimum value of about 15% in the middle of the silver layer. This suggests that at least some of the aluminum is present as aluminum oxide. The Auger spectrum obtained when analyzing the product of Example 7 was similar to that obtained in the previous example in that it showed an oxygen peak corresponding to the peak concentration of additional metals. This indicates that substantial oxidation of the stainless steel has occurred (the peak in iron concentration is observed at an etching time of 170 seconds; at the peak in iron concentration the coating concentration is 15 at.% iron, 7 % tin, 3 atomic % silver, 2 atomic % nickel and 73 atomic % nickel). Examples 12-15 demonstrate the effect of increasing the amount of titanium used as the additional metal. If the amount of titanium used is greater than the amount corresponding to a 5 nm thick titanium layer, the light transmittance of the product decreases to less than 80%. Similarly, the other metal used was 5n thick
When used in an amount corresponding to a metal layer of less than m,
generally gave the best results. The exceptions were lead and gold, which were most effective when used in amounts corresponding to a metal layer approximately 6-8 nm thick. As mentioned above, the amount of additional metal used depends on the corresponding layer thickness, i.e., the additional metal is not oxidized and there is no interdiffusion between the additional metal and the adjacent silver layer and anti-reflective metal oxide layer. The thickness of the additional layer that would be formed by sputtering the same amount of additional metal, assuming no additional metal.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the etching time and the concentration of the removed substance when an example of the product of the present invention containing copper as an additional metal is analyzed by Auger electron spectroscopy; FIG. 3 is a graph similar to FIG. 1 of another example of a product of the invention incorporating titanium as an additional metal; FIG. 3 is a further example of a product of the invention incorporating aluminum as an additional metal. This is a graph similar to Figure 1 of .

Claims (1)

[Scope of Claims] 1. In manufacturing a transparent substrate of glass or plastic coated with a low emissivity coating by cathode sputtering, sequentially: (i) a transparent substrate of glass or plastic coated with a 5-30 nm thick coating; (ii) sputtering on top of this silver layer one or more additional metals other than silver in an amount corresponding to a 0.5-10 nm thick layer; (iii) over the layer of silver and additional metal in the presence of oxygen or an oxidizing gas under conditions that would otherwise result in significant loss of the low emissivity properties of the coating that would form on the substrate. A method for producing a transparent substrate coated with a low emissivity coating, characterized in that the method comprises reactively sputtering one or more anti-reflective metal oxide layers. 2. When additional metal is later reactively sputtered onto the anti-reflective metal oxide layer or layers,
2. The method of claim 1, wherein the metal forms a colorless metal oxide. 3. The method of claim 1, wherein the additional metal is copper. 4. A method according to any one of claims 1 to 3, in which the additional metal is sputtered onto the silver layer in a total amount corresponding to a 1-5 nm thick layer. 5. A method according to any one of claims 1 to 4, wherein the sputtered silver layer is 8 to 15 nm thick. 6. Any one of claims 1 to 5, wherein the anti-reflective metal oxide layer is a layer of tin oxide, titanium oxide, indium oxide, tin oxide-doped indium oxide, bismuth oxide, or zirconium oxide. The method described in. 7. A method according to any one of claims 1 to 6, wherein the total thickness of the one or more anti-reflective metal oxide layers overlying the silver layer is between 20 and 60 nm. 8. In producing a transparent substrate of glass or plastic coated with a low emissivity coating by cathodic sputtering, the following steps are taken: (i) in the presence of oxygen or an oxidizing gas on the transparent substrate of glass or plastic; reactively sputtering one or more anti-reflective metal oxide layers; (ii) a 5-30 nm layer of anti-reflective metal oxide;
(iii) sputtering on top of this silver layer one or more additional metals other than silver in an amount corresponding to a 0.5-10 nm thick layer; (iv) ) the presence of oxygen or an oxidizing gas on the layer of silver and the additional metal under conditions that would otherwise result in a significant loss of the low emissivity properties of the coating that would form on the substrate; A method for producing a transparent substrate coated with a low emissivity coating, characterized in that the method comprises: reactively sputtering one or more anti-reflective metal oxide layers. 9. The anti-reflective metal oxide layer sputtered before the silver layer is a layer of tin oxide, titanium oxide, indium oxide, tin oxide doped indium oxide, bismuth oxide or zirconium oxide. Method. 10. The method of claim 8 or 9, wherein the total thickness of the anti-reflective metal oxide layer or layers sputtered before the silver layer is between 20 and 60 nm. 11. A method according to any one of claims 8 to 10, in which the sputtering process is facilitated by magnetic enhancement. 12 (a) Depositing a 30-50 nm thick anti-reflection layer of SnO ₂ by reactive sputtering of tin in the presence of oxygen or oxidizing gas on a glass substrate; (b) depositing the anti-reflection layer on the glass substrate; sputtering an 8-12 nm thick layer of silver on top of the layer; (c) sputtering an amount of copper equivalent to a 1-5 nm thick copper layer on top of said silver layer; then (d) thus on the coating formed by
9. A method as claimed in claim 8, in which an anti-reflection layer of SnO ₂ 30-50 nm thick is deposited by reactive sputtering of tin in the presence of oxygen or an oxidizing gas. 13. The method of claim 12, wherein the sputtering process is facilitated by magnetic enhancement. 14. A transparent substrate of glass or plastic coated with a low emissivity coating, on said transparent substrate, in sequence: (a) a silver layer with a thickness of 5-30 nm; (b) a metal layer with a total thickness of 0.5-10 nm. 1 corresponding to
one or more additional metals that are non-uniformly dispersed in the silver layer, with the concentration of the additional metal in the silver layer being at a maximum in the upper half of the silver layer; (c) A transparent substrate coated with a low emissivity coating, characterized in that it has a low emissivity coating consisting of one or more anti-reflective metal oxide layers. 15. The coated substrate of claim 14, wherein any additional metal is not completely dispersed in the silver layer, but extends over the top surface of the silver layer. 16. The coated substrate according to claim 14 or 15, wherein the additional metal is a metal that forms a colorless metal oxide. 17 Claim 14 in which the additional metal is copper
The coated substrate according to item 1 or item 15. 18. A coated substrate according to any one of claims 14 to 17, wherein the silver layer is 8 to 16 nm thick. 19. Coated substrate according to any one of claims 14 to 18, wherein the total amount of additional metal corresponds to a metal layer 1 to 5 nm thick. 20. A coated substrate according to any one of claims 14 to 18, wherein the total amount of additional metal corresponds to a metal layer with a thickness greater than 5 nm. 21. According to any one of claims 14 to 20, the anti-reflection metal oxide layer is tin oxide, titanium oxide, indium oxide, indium oxide doped with tin oxide, bismuth oxide, or zirconium oxide. coated substrate. 22. A coated substrate according to any one of claims 14 to 21, wherein the total thickness of the anti-reflective metal oxide layer or layers overlying the silver layer is between 20 and 60 nm. 23. The coated substrate according to any one of claims 14 to 22, having an emissivity of 0.2 or less and a light transmittance of at least 70%. 24. In a transparent substrate of glass or plastic coated with a low emissivity coating, on said transparent substrate, in sequence: (a) one or more anti-reflective metal oxide layers; (b) a 5-30 nm thick layer. silver layer, (c) 1 corresponding to a metal layer with a total thickness of 0.5 to 10 nm.
one or more additional metals that are non-uniformly dispersed in the silver layer, with the concentration of the additional metal in the silver layer being at a maximum in the upper half of the silver layer; (d) A transparent substrate coated with a low emissivity coating, characterized in that it has a low emissivity coating consisting of one or more anti-reflection metal oxide layers. 25. Claim 2, wherein the anti-reflective metal oxide layer below the silver layer is a layer of tin oxide, titanium oxide, indium oxide, tin oxide doped indium oxide, bismuth oxide or zirconium oxide.
The coated substrate according to item 4. 26. A coated substrate according to claim 24 or 25, wherein the total thickness of the anti-reflective metal oxide layer or layers below the silver layer is between 20 and 60 nm. 27. The coated substrate according to any one of claims 24 to 26, having an emissivity of 0.2 or less and a light transmittance of at least 70%. 28 Applying on a glass substrate sequentially (a) an anti-reflection layer of SnO ₂ 30-50 nm thick, (b) a silver layer 8-12 nm thick, and (c) a copper layer 1-5 nm thick. sufficient copper dispersed in the silver layer, such that the concentration of copper in the silver layer is maximum in the upper half of the silver layer; and (d) 30-50 nm thick. 25. The coated substrate of claim 24 having a low emissivity coating consisting of an anti-reflection layer of _SnO2 . 29. The coated substrate of claim 28, wherein the substrate has an emissivity of 0.2 or less and a light transmittance of at least 70%.