Patent Description:
A variety of transparent electrically conductive oxide (TCO) coatings are known in the art. Commonly, these coatings include an indium tin oxide film. In some cases, the indium tin oxide film is located beneath one or more overcoat films of silicon nitride, silicon oxynitride, or silicon dioxide. It would be desirable to provide an overcoat film that: (i) has a composition different from that of the TCO film, and yet (ii) contains one or more metals also found in the TCO film. It would be particularly desirable to provide an overcoat film of this nature that provides the coating with good durability and adheres well to indium tin oxide film and/or any other overcoat films, such as one or more overcoat films of silicon nitride, silicon oxynitride, or silicon dioxide. In such cases, it would be desirable for the coating and its films to have compositions and thicknesses that simultaneously achieve low sheet resistance and high visible transmission, preferably together with neutral color properties. <CIT> concerns low-e panels with high gain value, comprising an overcoat layer, which is divided into three sub-layers, wherein one of the sub-layers includes aluminium-tin oxide, with a low extinction coefficient. <CIT> describes multi-pane anti-solar insulating glazing units designed to reduce condensation water, wherein several examples comprise ITO.

The features of the claimed invention are provided in the independent claims, to which reference should now be made. Additional, optional features are provided in the dependent claims.

The following detailed description is to be read with reference to the drawings, in which like elements in different drawings have like reference numerals. Skilled artisans will recognize that the examples provided herein have many useful alternatives that fall within the scope of the invention.

Many embodiments of the invention involve a coated substrate. A wide variety of substrate types are suitable for use in the invention. In some embodiments, the substrate is a sheet-like substrate having generally opposed first and second major surfaces. For example, the substrate can be a sheet of transparent material (i.e., a transparent sheet). The substrate, however, is not required to be a sheet, nor is it required to be transparent.

For many applications, the substrate will comprise a transparent (or at least translucent) material, such as glass or clear plastic. For example, the substrate is a glass sheet (e.g., a window pane) in certain embodiments. A variety of known glass types can be used, such as soda-lime glass. In some cases, it may be desirable to use "white glass," a low iron glass, etc. In certain embodiments, the substrate is part of a window, door, skylight, or other glazing. Depending on the level of solar control desired, the present coating may be applied to tinted glass. Thus, the coating of any embodiment disclosed herein can optionally be provided on a sheet of tinted glass. This may provide particularly good selectivity.

Substrates of various sizes can be used in the present invention. Commonly, large-area substrates are used. Certain embodiments involve a substrate having a major dimension (e.g., a length or width) of at least about. <NUM> meter, preferably at least about <NUM> meter, perhaps more preferably at least about <NUM> meters (e.g., between about <NUM> meters and about <NUM> meters), and in some cases at least about <NUM> meters. In some embodiments, the substrate is a jumbo glass sheet having a length and/or width that is between about <NUM> meters and about <NUM> meters, e.g., a glass sheet having a width of about <NUM> meters and a length of about <NUM> meters. Substrates having a length and/or width of greater than about <NUM> meters are also anticipated.

Substrates of various thicknesses can be used in the present invention. In some embodiments, the substrate (which can optionally be a glass sheet) has a thickness of about <NUM>-<NUM>. Certain embodiments involve a substrate with a thickness of between about <NUM> and about <NUM>, and perhaps more preferably between about <NUM> and about <NUM>. In one particular embodiment, a sheet of glass (e.g., soda-lime glass) with a thickness of about <NUM> is used.

The substrate <NUM>' has opposed surfaces <NUM> and <NUM>, which preferably are opposed major surfaces. In some cases, surface <NUM> is destined to be an internal surface exposed to a between- pane space of an insulating glazing unit, while surface <NUM> is destined to be an external surface exposed to an interior of a building. This, however, will not be the case in all embodiments.

As shown in <FIG> and <FIG>, the substrate <NUM>' bears a transparent electrically conductive coating <NUM>. In <FIG>, the coating <NUM> includes, in sequence from surface <NUM> outwardly, an indium tin oxide film <NUM> and a tin oxide film <NUM>. In <FIG>, the coating <NUM> includes, from surface <NUM> outwardly, an optional base film <NUM>, the indium tin oxide film <NUM>, and the tin oxide film <NUM>. The films <NUM>, <NUM>, and <NUM> can be provided in the form of discrete layers, thicknesses of graded film, or a combination of both including at least one discrete layer and at least one thickness of graded film. While the base film <NUM> is shown as a single layer, it can alternatively be a plurality of layers. Preferably, all the films in the coating <NUM> are oxide, nitride, or oxynitride films. In some cases, all the films in the coating <NUM> are sputtered films.

The coating <NUM> preferably is formed of materials, and made by a process (as detailed herein), that allows the coated substrate to have a haze level of less than <NUM> or less than <NUM> (e.g., less than <NUM>, less than <NUM>, or even less than <NUM>), a roughness Ra of less than about <NUM>, less than about <NUM>, or less than about <NUM> (e.g., less than about <NUM>), and a monolithic visible transmission of greater than <NUM>% (preferably greater than <NUM>%).

Haze can be measured in well-known fashion, e.g., using a BYK Haze-Gard plus instrument. Reference is made to ASTM D <NUM>-<NUM>: Standard Test method for Haze and Luminous Transmittance of Transparent Plastics.

In certain embodiments, the coated substrate has a haze of less than <NUM> and a surface roughness of about less than <NUM>, together with a monolithic visible transmission of greater than <NUM>% (e.g., before and after heat treatment), greater than <NUM>% (e.g., before and after heat treatment), greater than <NUM>% (e.g., after heat treatment), greater than <NUM>% (e.g., after heat treatment), or even greater than <NUM>% in some cases (e.g., after heat treatment), in combination with a post-heat Rsheet of less than <NUM> ohms/square, less than <NUM> ohms/square, less than <NUM> ohms/square, less than <NUM> ohms/square, or in some cases even less than <NUM> ohms/square, such as about <NUM> to <NUM> ohms/square.

The coating <NUM> also has a low surface roughness. Preferably, the coating <NUM> has a surface roughness Ra of less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, less than <NUM>, or even less than <NUM>, such as about <NUM>. The deposition method and conditions preferably are chosen so as to provide the coating with such a roughness. Alternatively, the coating could be polished after deposition to reduce its surface roughness. Preferably, though, the coating exhibits the preferred surface roughness without requiring any polishing or the like (e.g., as-deposited).

Surface roughness is defined in terms deviations from the mean surface level. The surface roughness Ra is the arithmetical mean surface roughness. This is the arithmetic average of the absolute deviations from the mean surface level. The arithmetical mean surface roughness of a coating is commonly represented by the equation: Ra= <NUM>/L ∫<NUM>L | f(x) | dx. " The surface roughness Ra can be measured in conventional fashion, e.g., using an Atomic Force Microscope (AFM) equipped with conventional software that gives Ra.

When provided, the optional base film <NUM> can comprise, consist essentially of, or consist of silica, alumina, or a mixture of both. In other embodiments, the base film <NUM> comprises titanium dioxide. In still other embodiments, the base film <NUM> comprises tin oxide (e.g., SnO<NUM>). In such embodiments, the base film <NUM> may be devoid of indium. For example, a base film <NUM> consisting of (or at least consisting essentially of) tin oxide is provided in some cases. Combinations of two or more of silica, alumina, titanium dioxide, and tin oxide may be used as well. Alternatively, other dielectric films may be used.

Thus, in certain embodiments, in addition to the indium tin oxide film <NUM>, the coating <NUM> includes a film <NUM> comprising tin oxide located under the indium tin oxide film <NUM> in combination with a tin oxide film <NUM> located over the indium tin oxide film <NUM>.

The indium tin oxide film <NUM> comprises indium tin oxide optionally together with one or more other materials. If desired, zinc, aluminum, antimony, fluorine, carbon nanotubes, or other additives can be included in the film. Preferably, the indium tin oxide film <NUM> consists essentially of, or consists of, indium tin oxide. The indium tin oxide film <NUM> can contain various relative percentages of indium oxide and tin oxide. Indium oxide is the major constituent. That is, it accounts for more than <NUM>% of the film's total weight. Preferably, the composition of the film ranges from about <NUM>% indium oxide/<NUM>% tin oxide to about <NUM>% indium oxide/<NUM>% tin oxide, such as about <NUM>% indium oxide/<NUM>% tin oxide.

In embodiments where the tin oxide film <NUM> is provided, it is located over the indium tin oxide film <NUM>. In some cases, the tin oxide film <NUM> comprises fluorine. Preferably, the tin oxide film <NUM> is devoid of indium oxide. For example, the tin oxide film <NUM> may consist of (or at least consist essentially of) tin oxide (e.g., SnO<NUM>). In certain embodiments, film <NUM> contains at least <NUM>% tin oxide, at least <NUM>% tin oxide, or at least <NUM>% tin oxide (based on the total weight of the film), while also being devoid of indium oxide.

In some embodiments, the coating <NUM> includes a nitride film between the indium tin oxide film <NUM> and the tin oxide film <NUM>. The nitride film may comprise one or more of silicon nitride, aluminum nitride, and titanium nitride. For example, a thin film of silicon nitride can optionally be positioned directly between (i.e., so as to contact both) the indium tin oxide film and the tin oxide film. When provided, this silicon nitride film (which can optionally include a small amount of aluminum) may have a thickness of less than 250Å, or even less than 200Å, e.g., about 150Å.

In other embodiments, the tin oxide film <NUM> is in contact with the indium tin oxide film <NUM>. Providing the tin oxide film <NUM> directly over (i.e., so as to be in contact with) the underlying indium tin oxide film <NUM> can be advantageous in that, while these two films have different compositions, both contain tin oxide and may provide exceptional adhesion to each other. This film combination may also make the coating particularly smooth, thus creating a coated surface that is easier to clean, remove label residue, etc..

When provided, the optional base film <NUM> has a thickness of 50Å or more, such as about <NUM>-300Å. In certain embodiments, the coating includes a base film of silica (optionally including some aluminum), alumina, titanium dioxide, or tin oxide at a thickness of <NUM>-150Å.

In other embodiments, the indium tin oxide film <NUM> is directly on (i.e., in contact with) the substrate surface <NUM>. In these embodiments, there is of course no base film <NUM>. Applicant has found that good results can be achieved in cases where indium tin oxide film is directly on soda- lime float glass.

Preferably, the indium tin oxide film <NUM> has a thickness of between 100Å and <NUM>,000Å. In certain embodiments, the indium tin oxide film <NUM> has a thickness of less than <NUM>,750Å, such as between <NUM>,000Å and <NUM>,600Å, or even less than <NUM>,500Å, such as about <NUM>,<NUM>-<NUM>,400Å. The thicknesses recited herein are physical thicknesses unless otherwise specified to be optical thicknesses.

The indium tin oxide film <NUM> preferably has a sheet resistance of less than <NUM> ohms/square. In certain embodiments, the sheet resistance is less than <NUM> ohms/square, or even less than <NUM> ohms/square, such as about <NUM>-<NUM> ohms/square.

When provided, the tin oxide film <NUM> can have a thickness of between 90Å and <NUM>,200Å. In certain embodiments, the film <NUM> has a thickness of between <NUM>Å and <NUM>Å, such as between <NUM>Å and <NUM>Å, e.g., about <NUM>Å.

Some embodiments provide the thickness of the indium tin oxide film <NUM> in the range of about <NUM>,<NUM>-<NUM>,500Å in combination with the thickness of the tin oxide film <NUM> being about <NUM>- 700Å. This combination of thicknesses, however, is not required for all embodiments. Rather, this combination of thicknesses is merely used in one group of embodiments. This combination of thicknesses, however, can optionally be provided in any embodiment hereof that includes both film <NUM> and film <NUM> (i.e., in any embodiment having any of the noted combinations of other features and properties described herein).

Table <NUM> below shows four exemplary film stacks that can be used as coating <NUM> (here, it will be appreciated that the tin oxide film is the outermost film of the coating):.

These film stacks represent a broader group of embodiments wherein the coating <NUM> has a total thickness of less than <NUM>,400Å. A base film (e.g., silica at about 100Å) can optionally be added. Additionally or alternatively, a nitride film (e.g., silicon nitride at about 150Å) may be added between the ITO and SnO<NUM> films.

The coating <NUM> can optionally further include an oxynitride film <NUM> located over the tin oxide film <NUM>. Reference is made to <FIG>. When provided, the oxynitride film <NUM> can have a thickness of between 100Å and <NUM>,300Å, such as between <NUM> angstroms and <NUM> angstroms. The oxynitride film <NUM> can optionally be directly over (i.e., so as to contact) the tin oxide film <NUM>. The oxynitride film <NUM> may comprise aluminum, oxygen, and nitrogen. In certain embodiments, the oxynitride film <NUM> is an exposed outermost film of the coating <NUM>.

In some cases, the oxynitride film <NUM> comprises silicon oxynitride at a thickness of between 400Å and 900Å. The silicon oxynitride may, for example, be sputter deposited from one or more silicon-aluminum targets, such as elemental targets comprising a sputterable material consisting of about <NUM>% silicon and <NUM>% aluminum.

In certain embodiments, the coating <NUM> includes a film comprising titanium oxide <NUM>. When provided, the film comprising titanium oxide <NUM> can be located over the tin oxide film <NUM>. Furthermore, when both the optional oxynitride film <NUM> and the optional film comprising titanium oxide <NUM> are provided, the film comprising titanium oxide is located over the oxynitride film. In preferred embodiments, the film comprising titanium oxide <NUM> has a thickness of less than 200Å, such as from <NUM>-75Å, e.g., about 50Å.

Preferably, the film comprising titanium oxide <NUM> is photocatalytic, hydrophilic, or both. Suitable films are described in <CIT> and<CIT> and <CIT>and <CIT> and <CIT> and <CIT> and <CIT>and <CIT>.

In some embodiments, the coated substrate <NUM>' is part of a monolithic glazing. In other embodiments, the coated substrate <NUM>' is part of a multi-pane insulating glazing unit ("IG unit") <NUM>.

In one group of embodiments, the coating <NUM> is on a #<NUM> surface, a #<NUM> surface, or another external surface of the inboard pane of an IG unit <NUM>. By providing the transparent electrically conductive coating <NUM> on this surface, the temperature of this indoor pane under certain conditions can be decreased. In such cases, by providing a photocatalytic and/or hydrophilic film comprising titanium oxide <NUM> over the rest of the coating <NUM>, any condensation that may occur on the room-side surface may be more readily formed into a sheet and evaporated.

Thus, certain embodiments provide a coated substrate (e.g., a glass pane) having the following films in sequence moving outwardly from the substrate (though, not necessarily in contiguous sequence): indium tin oxide film/tin oxide film/film comprising titanium oxide, or: indium tin oxide film/tin oxide film/oxynitride film/film comprising titanium oxide. The film comprising titanium oxide can be, for example, a TiO<NUM> film or a film comprising both titanium oxide and tungsten oxide (e.g., about <NUM>% W). The film comprising titanium oxide can have a physical thickness of less than 200Å, or even less than 75Å, such as about 50Å. In the present embodiments, the film comprising titanium oxide <NUM> can be the outermost (i.e., exposed) film of the coating <NUM>.

Referring to the embodiments of <FIG>, the "first" (or "#<NUM>") surface is exposed to an outdoor environment. Accordingly, it is the #<NUM> surface that radiation from the sun first strikes. The external surface of the outboard pane is the so-called first surface. Moving from the #<NUM> surface toward the interior of the building, the next surface is the "second" (or "#<NUM>") surface. Thus, the internal surface of the outboard pane is the so-called second surface. Moving further toward the interior of the building, the next surface is the "third" (or "#<NUM>") surface, followed by the "fourth" (or "#<NUM>") surface. This convention is carried forward for IG units having more than four major pane surfaces. Thus, for a triple-pane IG unit, the #<NUM> surface would be the external surface of the inboard pane.

One group of embodiments provides a triple glazing (e.g., an IG unit having three panes), and coating <NUM> is provided on the #<NUM> surface of the glazing. In embodiments of this nature, the #<NUM> and/or #<NUM> surfaces may have other functional coatings. The #<NUM> surface, for example, may also have a transparent electrically conductive coating <NUM>', and/or the #<NUM> surface may have a silver- based low-emissivity coating.

In some cases, the substrate <NUM>' is heated prior to film deposition, during deposition, or both. Additionally or alternatively, the coated substrate <NUM>' can be heat treated after being coated. If desired, the post-deposition heat treatment (such as glass tempering) can be performed in air. When the coated substrate <NUM>' is heat treated, defects in the film can be healed and improvement of crystalline structure can occur in the indium tin oxide film <NUM> without an uncontrollable change in the chemistry of this transparent conductive film. When provided, the tin oxide film <NUM>, optionally together with one or more overlying films of the nature described above, may provide resistance to oxygen reaching and reacting with the indium tin oxide film <NUM> so as to cause uncontrollable change in its chemistry during heat treatment. The film materials and thicknesses described herein are believed to be suitable for accomplishing this object.

In certain embodiments, the coating <NUM> is on a glass pane, and this coated glass pane is heat treated through a process that leaves the coated glass cut-able by conventional glass cutting techniques. The heat treatment, for example, can involve using lower temperature for conversion so as to maintain the stress in the glass such that the coated glass remains cut-able even after the heat treatment.

In <FIG>, the substrate <NUM>' is a transparent pane that is part of an IG unit <NUM>. Commonly, the IG unit <NUM> has an exterior pane <NUM> and an interior pane <NUM>' separated by at least one between-pane space <NUM>. A spacer <NUM> (which can optionally be part of a sash) is provided to separate the panes <NUM> and <NUM>'. The spacer <NUM> can be secured to the internal surfaces of each pane using an adhesive or seal <NUM>. In some cases, an end sealant <NUM> is also provided. In the illustrated embodiments, the exterior pane <NUM> has an external surface <NUM> (the #<NUM> surface) and an internal surface <NUM> (the #<NUM> surface). The interior pane <NUM>' has an internal surface <NUM> (the #<NUM> surface) and, in some cases (i.e., when the IG unit is a double-pane unit), an external surface <NUM> (the #<NUM> surface). In other embodiments, the IG unit <NUM> has three panes, such that the external surface <NUM> of the interior pane <NUM>' is the #<NUM> surface.

The IG unit <NUM> can optionally be mounted in a frame (e.g., a window sash or frame) such that the external surface <NUM> of the exterior pane <NUM> is exposed to an outdoor environment <NUM> while the external surface <NUM> of the interior pane <NUM>' is exposed to a room-side interior environment. Each internal surface of the unit is exposed to a between-pane space <NUM> of the IG unit. In some embodiments, the IG unit <NUM> is a vacuum IG unit. If desired, the IG unit <NUM> may have a between-pane <NUM> filled with an aerogel.

The IG unit <NUM> includes a transparent electrically conductive coating <NUM> in accordance with any embodiment described herein. In the embodiment of <FIG>, the external surface <NUM> of pane <NUM>' bears a transparent electrically conductive coating <NUM>. Here, the illustrated coating <NUM> is exposed to an environment (in some cases, a temperature-controlled living space) inside a home or another building.

The IG unit <NUM> can further include one or more films comprising titanium oxide <NUM>, such as a hydrophilic and/or photocatalytic film. In the embodiment of <FIG>, for example, a film comprising titanium oxide <NUM> is provided on the external surface <NUM> of pane <NUM>, so as to be exposed to an outdoor environment <NUM> (and thus in periodic contact with rain). The film comprising titanium oxide <NUM> can be part of a photocatalytic and/or hydrophilic coating. If desired, the IG unit <NUM> can bear two films comprising titanium oxide, e.g., one such film <NUM> on the external surface <NUM> of pane <NUM> and another such film <NUM> over the rest of the coating <NUM> on the external surface <NUM> of pane <NUM>'.

Thus, in some cases, there are two films comprising titanium oxide <NUM> on the IG unit. When provided, these two coatings may be different. For example, the external surface of the outboard pane and the external surface of the inboard pane can both have photocatalytic films, but they can be different (e.g., in terms of thickness or composition). For example, a photocatalytic film on the external surface of the inboard pane can be adapted for activation by indoor light, while a photocatalytic film on the external surface of the outboard pane may require direct sunlight for activation. More generally, the indoor photocatalytic film may have a higher level of photoactivity (e.g., it may be thicker or have a more highly photoactive composition) than the outside photocatalytic film. When provided, the films comprising titanium may, of course, be applied over one or more other films.

The IG unit <NUM> may also include one or more low-emissivity coatings <NUM>. In the embodiment of <FIG>, the IG unit includes a low-emissivity coating <NUM> on the internal surface <NUM> of pane <NUM>. When provided, the low-emissivity coating <NUM> preferably includes at least one silver-inclusive film, which preferably contains more than <NUM>% silver by weight (e.g., a metallic silver film). If desired, a low-emissivity coating <NUM> can alternatively be on the internal surface <NUM> of pane <NUM>'. In some embodiments, the coating <NUM> includes three or more infrared-reflective films (e.g., silver-containing films). Low-emissivity coatings with three or more infrared-reflective films are described in <CIT> and<CIT>and <CIT> and <CIT> and <CIT> and <CIT> and<CIT>. In other cases, the low-emissivity coating can be a "single silver" or "double silver" low-emissivity coating, which are well-known to skilled artisans. Thus, certain embodiments provide the IG unit <NUM> with a single silver low-emissivity coating, e.g., on the #<NUM> surface in combination with coating <NUM> on an external pane surface of the IG unit.

If desired, the embodiment of <FIG> can have a low-emissivity coating on surface <NUM> or on surface <NUM>. Similarly, the embodiment of <FIG> can optionally have a low-emissivity coating on surface <NUM> or on surface <NUM>.

While the embodiment of <FIG> shows the transparent electrically conductive coating <NUM> being on the #<NUM> surface of an IG unit <NUM>, the #<NUM> surface of the IG unit can alternatively be provided with a transparent electrically conductive coating. In such cases, there can optionally be a low-emissivity coating on surface <NUM> or on surface <NUM>.

<FIG> shows an IG unit <NUM> having a first transparent electrically conductive coating <NUM> on the #<NUM> surface of the IG unit, while a second transparent electrically conductive coating <NUM>' is on the #<NUM> surface of the IG unit. For triple glazed IG units, a first transparent electrically conductive coating can be provided on the #<NUM> surface of the IG unit, while a second transparent electrically conductive coating is provided on the #<NUM> surface of the IG unit. Or, there can simply be a single transparent electrically conductive coating on the #<NUM> surface.

Thus, it can be appreciated that the transparent electrically conductive coating <NUM> may be provided on one or more of the following IG unit surfaces: the #<NUM> surface, the #<NUM> surface (for a double glazing), and the #<NUM> surface (for a triple glazing). When applied on the #<NUM> surface, the pane will stay warmer and have less condensation. When applied on a #<NUM> or #<NUM> surface, the inboard pane will stay cooler and save energy, but it may catch condensation. In such cases, a hydrophilic and/or photocatalytic coating may be provided over coating <NUM> so as to encourage rapid evaporation of any condensation that may occur. The transparent electrically conductive coating <NUM> can also be beneficial for a monolithic glazing, a laminated glass glazing, etc..

The present coating <NUM> has a number of beneficial properties. The ensuing discussion reports several of these properties. In some cases, properties are reported herein for a single (i.e., monolithic) pane <NUM>' bearing the present coating <NUM> on one surface <NUM> ("the present pane"). In other cases, these properties are reported for a double-pane IG unit <NUM> having the transparent electrically conductive coating <NUM> on the #<NUM> surface <NUM> and a triple silver low-emissivity coating on the #<NUM> surface. The triple silver low-emissivity coating is known commercially as the LoE<NUM>- <NUM>™product from Cardinal CG Company. In such cases, the reported properties are for an IG unit wherein both panes are clear <NUM> soda lime float glass with a ½ inch between-pane space filled with an insulative gas mix of <NUM>% argon and <NUM>% air ("the present IG unit"). Of course, these specifics are by no means limiting to the invention. For example, the transparent electrically conductive coating can alternatively be provided on the #<NUM> surface of the IG unit, the low-emissivity coating can alternatively be on the #<NUM> surface, the low-emissivity coating can alternatively be a single or double silver low-emissivity coating, etc. Absent an express statement to the contrary, the present discussion reports determinations made using the well-known WINDOW <NUM> computer program (e.g., calculating center of glass data) under NFRC100-<NUM> conditions.

As already explained, the indium tin oxide film <NUM> is electrically conductive and imparts low sheet resistance in the coating <NUM>. The sheet resistance of the present coating <NUM> is less than <NUM>Ω/square. Preferably, the sheet resistance of this coating <NUM> is <NUM>Ω/square or less, such as less than <NUM>Ω/square (e.g., less than <NUM>Ω/square, less than <NUM>Ω/square, or even less than <NUM>Ω/square). The sheet resistance of the coating can be measured in standard fashion using a non-contact sheet resistance meter.

The coating <NUM> also has low emissivity. The emissivity of the coating <NUM> is less than <NUM>. Preferably, the emissivity is <NUM> or less, such as less than <NUM>, less than <NUM>, less than <NUM>, or even less than <NUM>, such as about <NUM>. In contrast, an uncoated pane of clear glass would typically have an emissivity of about <NUM>.

The term "emissivity" is well known in the present art. This term is used herein in accordance with its well-known meaning to refer to the ratio of radiation emitted by a surface to the radiation emitted by a blackbody at the same temperature. Emissivity is a characteristic of both absorption and reflectance. It is usually represented by the formula:
E = <NUM> - Reflectance. The present emissivity values can be determined as specified in "Standard Test Method for Emittance of Specular Surfaces Using Spectrometric Measurements," NFRC <NUM>-<NUM>.

In addition to low sheet resistance and low emissivity, the U Value of the present IG unit <NUM> is very low. As is well known, the U Value of an IG unit is a measure of the thermal insulating property of the unit. The smaller the U value, the better the insulating property of the unit. The U Value of the present IG unit is less than <NUM> (i.e., center of glass U value), preferably less than <NUM>, more preferably less than <NUM>, and perhaps optimally less than <NUM>, such as from <NUM>-<NUM>.

The term U Value is well known in the present art. It is used herein in accordance with its well-known meaning to express the amount of heat that passes through one unit of area in one unit of time for each unit of temperature difference between a hot side of the IG unit and a cold side of the IG unit. The U Value can be determined in accordance with the standard specified for Uwinter in NFRC <NUM>-<NUM>.

A tradeoff is sometimes made in low U value coatings whereby the film(s) selected to achieve a low U value have the effect of decreasing the visible transmittance to a lower level than is desired and/or increasing the visible reflectance to a higher level than is ideal. As a consequence, windows bearing these coatings may have unacceptably low visible transmission, a somewhat mirror-like appearance, or suboptimal color properties.

In combination with the beneficial properties discussed above, the present coating <NUM> has good optical properties. As noted above, a tradeoff is sometimes made in low U value coatings whereby the films selected to achieve a low U value have the effect of restricting the visible transmission to a level that is lower than ideal.

To the contrary, the present coating <NUM> provides a good combination of these properties. For example, the present IG unit <NUM> (and the present pane <NUM>', whether monolithic or as part of the IG unit <NUM>) has a visible transmittance Tv of greater than <NUM> (i.e., greater than <NUM>%). Preferably, the present IG unit <NUM> (and the present pane <NUM>', whether monolithic or insulated) achieves a visible transmittance Tv of greater than <NUM> (i.e., greater than <NUM>%), or greater than <NUM> (i.e., greater than <NUM>%), such as about <NUM>.

Further, if the triple silver low-emissivity coating is replaced with a double silver low- emissivity coating like the LoE<NUM>-<NUM>™ or LoE<NUM>-<NUM>™ coatings from Cardinal CG Company, then the present IG unit <NUM> (and the present pane <NUM>', whether monolithic or insulated) can exhibit a visible transmittance Tv of greater than <NUM> (i.e., greater than <NUM>%), or even greater than <NUM>.

Moreover, if the triple silver low-emissivity coating is replaced with a single silver low-emissivity coating like the LoE-<NUM>™ coating from Cardinal CG Company, then the present IG unit <NUM> (and the present pane <NUM>', whether monolithic or insulated) can exhibit a visible transmittance Tv of greater than <NUM> (i.e., greater than <NUM>%), or even greater than <NUM>.

While the desired level of visible transmittance can be selected and varied to accommodate different applications, certain preferred embodiments provide a coated pane <NUM>' having a post-heat-treatment monolithic visible transmission of greater than <NUM>%, greater than <NUM>%, or even greater than <NUM>%.

The term "visible transmittance" is well known in the art and is used herein in accordance with its well-known meaning to refer to the percentage of all incident visible radiation that is transmitted through the IG unit <NUM>. Visible radiation constitutes the wavelength range of between about <NUM> and about <NUM>. Visible transmittance, as well as visible reflectance, can be determined in accordance with NFRC <NUM>-<NUM>, Standard Test Method for Determining the Solar and Infrared Optical Properties of Glazing Materials and Fading Resistance of Systems. The well-known WINDOW <NUM> computer program can be used in calculating these and other reported optical properties.

The present coating <NUM> can provide a visible absorption of less than <NUM>%. Preferably, the visible absorption is less than <NUM>% (e.g., after heat treatment).

The present coating <NUM> can achieve desirable reflected color properties in combination with excellent thermal insulating properties. For example, the present IG unit <NUM> preferably exhibits an exterior reflected color characterized by an "a" color coordinate of between -<NUM> and <NUM> (e.g., between -<NUM> and <NUM>, such as about -<NUM>) and a "b" color coordinate of between -<NUM> and <NUM> (e.g., between -<NUM> and -<NUM>, such as about -<NUM>).

The present discussion of color properties is reported using the well-known color coordinates of "a" and "b. " In more detail, these color coordinates result from conventional use of the well-known Hunter Lab Color System (Hunter methods/units, Ill. D65, <NUM> degree observer). The present color properties can be determined as specified in ASTM Method E <NUM>.

In certain embodiments, the foregoing color properties are provided in combination with the sheet resistance, emissivity, U value, and visible transmission properties reported above. For example, the following chart depicts preferred combinations of properties in accordance with certain embodiments (the tabulated properties are after heat treatment).

In one embodiment, a multiple-pane insulating glazing unit includes an internal pane surface bearing a low-emissivity coating that has only one film comprising silver. The film comprising silver preferably contains at least <NUM>% silver by weight. The low-emissivity coating is exposed to a between-pane space of the IG unit. A desired one of the two external pane surfaces bears a coating <NUM> comprising both an indium tin oxide film <NUM> and a tin oxide film <NUM>. The tin oxide film <NUM> is located over the indium tin oxide film <NUM>. In the present embodiments, the indium tin oxide film <NUM> has a sheet resistance of less than <NUM> ohms/square and a thickness of between <NUM>,000Å and <NUM>,600Å, while the tin oxide film <NUM> has a thickness of between 90Å and <NUM>,200Å, and preferably is devoid of indium oxide. In the present embodiments, the IG unit has a U value of less than <NUM> together with a visible transmission of greater than <NUM>%. In addition, the IG unit exhibits an exterior reflected color characterized by an "ah" color coordinate of between -<NUM> and <NUM> and a "bh" color coordinate of between -<NUM> and -<NUM>.

In another embodiment, an IG unit includes an internal pane surface bearing a low-emissivity coating that has only two films comprising silver. Preferably, each film comprising silver contains at least <NUM>% silver by weight. The low-emissivity coating is exposed to a between-pane space of the IG unit. A desired one of the two external pane surfaces bears a coating <NUM> comprising both an indium tin oxide film <NUM> and a tin oxide film <NUM>. The tin oxide film <NUM> is located over the indium tin oxide film <NUM>. In the present embodiments, the indium tin oxide film <NUM> has a sheet resistance of less than <NUM> ohms/square and a thickness of between <NUM>,000Å and <NUM>,600Å, while the tin oxide film <NUM> has a thickness of between 90Å and <NUM>,200Å, and preferably is devoid of indium oxide. In the present embodiments, the IG unit has a U value of less than <NUM> together with a visible transmission of greater than <NUM>%. In addition, the IG unit exhibits an exterior reflected color characterized by an "ah" color coordinate of between -<NUM> and <NUM> and a "bh" color coordinate of between -<NUM> and -<NUM>.

In still another embodiment, an IG unit includes an internal pane surface bearing a low-emissivity coating that includes three films comprising silver. Preferably, each film comprising silver contains at least <NUM>% silver by weight. The low-emissivity coating is exposed to a between-pane space of the IG unit. A desired one of the two external pane surfaces bears a coating <NUM> comprising both an indium tin oxide film <NUM> and a tin oxide film <NUM>. The tin oxide film <NUM> is located over the indium tin oxide film <NUM>. In the present embodiments, the indium tin oxide film <NUM> has a sheet resistance of less than <NUM> ohms/square and a thickness of between <NUM>,000Å and <NUM>,600Å, while the tin oxide film <NUM> has a thickness of between 90Å and <NUM>,200Å, and preferably is devoid of indium oxide. In the present embodiments, the IG unit has a U value of less than <NUM> together with a visible transmission of greater than <NUM>%. In addition, the IG unit exhibits an exterior reflected color characterized by an "ah" color coordinate of between -<NUM> and 1and a "bh" color coordinate of between -<NUM> and -<NUM>.

In the foregoing three embodiments, the IG unit can, for example, be a double-pane unit with coating <NUM> on the #<NUM> surface and the low-emissivity coating on the #<NUM> surface. Coating <NUM> can consist of the following layers: silicon dioxide at about 100Å/ITO (<NUM>% In/<NUM>% Sn) at about <NUM>,<NUM>-<NUM>,400Å/tin oxide at about 150Å/SiON at about 900Å. The low-emissivity coating in the first of the foregoing three embodiments can, for example, be a single-silver low-emissivity coating like the commercially available LoE-<NUM>™ coating from Cardinal CG Company of Eden Prairie, Minnesota, USA. The low-emissivity coating in the second of the foregoing three embodiments can, for example, be a double-silver low-emissivity coating like the commercially available LoE<NUM>-<NUM>™ or LoE<NUM>-<NUM>™ coatings from Cardinal CG Company. The low-emissivity coating in the third of the foregoing three embodiments can, for example, be a triple-silver low-emissivity coating like the commercially available LoE<NUM>-<NUM>™ coating from Cardinal CG Company.

The invention provides one particular group of embodiments wherein the coating <NUM> has an intermediate level of electrical conductivity. In this particular group of embodiments, the tin oxide overcoat layer <NUM>, while preferred, need not always be present. The sheet resistance and emissivity are higher than the preferred and more preferred ranges tabulated above. Specifically, the emissivity ranges from <NUM> to <NUM>. The monolithic visible transmission (Tvis monolithic) preferably is greater than <NUM>%, more preferably is greater than <NUM>%, and perhaps optimally is greater than <NUM>% (e.g., after heat treatment). The visible absorption preferably is less than <NUM>%, and more preferably is less than <NUM>% (e.g., after heat treatment). In the present embodiments, the indium tin oxide film preferably has a thickness of between 100Å and <NUM>,000Å, such as between 100Å and <NUM>,200Å. In some of the present embodiments, the thickness of the indium tin oxide film is greater than 100Å but less than <NUM>,100Å, less than 750Å, less than 500Å, or even less than 300Å. One exemplary non-heat-treated coating that may be useful for the present embodiments has a layer of ITO on a glass substrate, where the ITO layer has a thickness of about <NUM>,060Å. In this case, the emissivity is about <NUM>. In another example, a heat-treated coating has the following layer stack: glass/ITO at about 170Å/SnO<NUM> at about <NUM>,135Å/SiON at about 560Å. In this case, the post-heat-treatment emissivity is about <NUM>. In still another example, a heat-treated coating has the following layer stack: glass/ITO at about 520Å/SnO<NUM> at about 785Å/SiON at about 560Å. In this case, the post-heat-treatment emissivity is about <NUM>. If desired, a base coat <NUM> of the nature described previously may be added to any of these film stacks. Additionally or alternatively, a layer comprising titanium oxide may be added.

The invention also provides methods for producing the present coating <NUM>. In preferred embodiments, the films are deposited by sputtering. Sputtering is well known in the present art.

In accordance with the present methods, a substrate <NUM>' having a surface <NUM> is provided. If desired, this surface <NUM> can be prepared by suitable washing or chemical preparation. The present coating <NUM> is deposited on the surface <NUM> of the substrate <NUM>', e.g., as a series of discrete layers, as a thickness of graded film, or as a combination including at least one discrete layer and at least one thickness of graded film. The coating can be deposited using any thin film deposition technique that is suitable for depositing the desired film materials at the desired low haze and roughness levels. Thus, the present invention includes method embodiments wherein, using any one or more appropriate thin film deposition techniques, the films of any embodiment disclosed herein are deposited sequentially upon a substrate (e.g., a sheet of glass or plastic). One preferred method utilizes DC magnetron sputtering, which is commonly used in industry. Reference is made to Chapin's <CIT>. In some cases, the present coatings are sputtered by AC or pulsed DC from a pair of cathodes. HiPIMS and other modern sputtering methods can be used as well.

Briefly, magnetron sputtering involves transporting a substrate <NUM>' through a series of low-pressure zones (or "chambers" or "bays") in which the various film regions that make up the coating are sequentially applied. To deposit oxide film, the target may be formed of an oxide itself, and the sputtering may proceed in an inert or oxidizing atmosphere. To deposit indium tin oxide, for example, a ceramic indium tin oxide target can be sputtered in an inert or oxidizing atmosphere. Alternatively, the oxide film can be deposited by sputtering one or more metallic targets (e.g., of metallic indium tin material) in a reactive atmosphere. Tin oxide can be deposited by sputtering one or more tin targets in a reactive atmosphere containing oxygen gas. Silicon nitride can be deposited by sputtering one or more silicon targets (which may be doped with aluminum or the like to improve conductivity) in a reactive atmosphere containing nitrogen gas. Silicon oxynitride can be deposited by sputtering one or more silicon targets (which may be doped with aluminum or the like) in a reactive atmosphere containing oxygen and nitrogen gas. Titanium dioxide can be deposited by sputtering one or more titanium targets (which may be doped with tungsten or the like) in a reactive atmosphere containing oxygen gas. The thickness of the deposited films can be controlled by varying the speed of the substrate, by varying the power on the targets, or by varying the ratio of power to partial pressure of the reactive gas.

Following is a non-limiting method for depositing one embodiment of the present coating <NUM> onto a glass substrate. A pair of rotatable metallic indium-tin targets is sputtered while an uncoated glass substrate is conveyed past the activated targets at a rate of about <NUM> inches per minute when depositing the ITO film. In this example, the relative weight amounts of the two metals in the sputterable material of the target is: indium <NUM>%, tin <NUM>%. Here, a power of <NUM> kW is used for the pair of rotary targets. The sputtering atmosphere is <NUM> mTorr with a gas flow of <NUM> sccm of argon and <NUM> sccm of oxygen. The resulting indium tin oxide film has a thickness of about 520Å. Directly over this ITO film, a tin oxide film is applied. Here, the tin oxide is applied at a thickness of about 785Å by conveying the glass sheet at about <NUM> inches per minute past a pair of rotary tin targets sputtered at <NUM> kW in a <NUM> mTorr atmosphere with a gas flow of <NUM> sccm of oxygen and <NUM> sccm of argon. Directly over the tin oxide film, a silicon oxynitride film is applied at a thickness of about 560Å by conveying the glass sheet at about <NUM> inches per minute past a pair of rotary silicon targets (<NUM>% Si, <NUM>% Al, by weight) sputtered at <NUM> kW in a <NUM> mTorr atmosphere with a gas flow of <NUM> sccm of oxygen and <NUM> sccm of nitrogen.

The coated substrate is then heat treated. Various heat treatment processes can be used. For example, the coated substrate can be heat treated on a conventional production tempering line. In tempering, glass is placed in a furnace maintained at about <NUM>-<NUM> (preferably controlled to <NUM>-<NUM>). The glass is typically held in the furnace for <NUM>-<NUM> seconds with constant movement to better ensure temperature uniformity of the product. This is intended to raise the glass temperature to about <NUM>. The glass is then removed from the furnace and placed in a stream of air for about <NUM> seconds such that the glass is cool enough for an operator to handle. Moreover, as already explained, the substrate can alternatively be heated prior to film deposition, during deposition, or both.

In certain embodiments, the tin oxide film <NUM> is omitted from the coating <NUM> and is replaced with an alloy oxide overcoat film <NUM>'. Reference is made to <FIG>. In such embodiments, the alloy oxide overcoat film <NUM>' is located over the indium tin oxide film <NUM>. In the present embodiments, the indium tin oxide film <NUM> can be of the nature (e.g., can have a thickness and conductivity) described above. By saying "alloy" in referring to the alloy oxide overcoat film, we simply mean the oxide overcoat film includes two or more elements selected from metals and metalloids. The alloy oxide overcoat film <NUM>' includes both tin and at least one other metal or metalloid. In any such embodiment, the alloy oxide overcoat film <NUM>' can optionally be an exposed outermost film of the coating <NUM>. Additionally or alternatively, the alloy oxide overcoat film <NUM>' can optionally be in contact with the indium tin oxide film <NUM>.

For any of the present embodiments, the alloy oxide overcoat film <NUM>' can have a thickness of between <NUM> angstroms and <NUM>,<NUM> angstroms, in combination with indium tin oxide film <NUM> having a thickness of between <NUM> angstroms and <NUM>,<NUM> angstroms. For example, the alloy oxide overcoat film <NUM>' can have a thickness of from <NUM> angstroms to <NUM>,<NUM> angstroms, or from <NUM> angstroms to <NUM>,<NUM> angstroms, or from <NUM> angstroms to <NUM> angstroms, or from <NUM> angstroms to <NUM> angstroms, or from <NUM> angstroms to <NUM>,<NUM> angstroms. On the other hand, indium tin oxide film <NUM> can have a thickness of from <NUM> angstroms to <NUM>,<NUM> angstroms, or from <NUM>,<NUM> angstroms to <NUM>,<NUM> angstroms, or from <NUM>,<NUM> angstroms to <NUM>,<NUM> angstroms, or even from <NUM>,<NUM> angstroms to <NUM>,<NUM> angstroms. Any thickness range mentioned in this paragraph or elsewhere in this disclosure for indium tin oxide film <NUM> can be provided in combination with any thickness ranges mentioned in this paragraph or elsewhere in this disclosure for the alloy oxide overcoat film <NUM>'.

In any embodiment that includes the alloy oxide overcoat film <NUM>', the coating <NUM> can optionally be devoid of a metal layer, or at least devoid of a silver layer. This, however, is not required in all cases. In embodiments where the coating <NUM> is devoid of a metal layer, skilled artisans will appreciate that a coating having a metal layer (e.g., any of the low-emissivity coatings described above) can optionally be provided on a different surface of the IG unit (i.e., on a surface that does not bear coating <NUM>).

Further, in any embodiment that includes the alloy oxide overcoat film <NUM>', the coating <NUM> can optionally include one or more films between film <NUM> and the substrate <NUM>'. Such additional film(s) can comprise, for example, silicon dioxide, silicon oxynitride, silicon nitride, or tin oxide. Reference is made to <FIG>, with the idea that film <NUM> shown in <FIG> would be replaced with film <NUM>' but that the discussion of optional film <NUM> still applies. Furthermore, the coating <NUM> in the present embodiments can optionally include one or more films between film <NUM> and the alloy oxide overcoat film <NUM>'. Such additional film(s) can comprise, for example, silicon nitride or tin oxide. Additionally or alternatively, one or more films can be provided over the alloy oxide overcoat film <NUM>'. As non-limiting examples, such films can comprise silicon nitride, silicon oxynitride, silicon oxide, or titanium dioxide. Reference is made to <FIG>, with the idea that film <NUM> shown in <FIG> would be replaced with film <NUM>' but that the discussion of optional film <NUM> still applies. Similarly, reference is made to <FIG>, with the idea that film <NUM> shown in <FIG> would be replaced with film <NUM>' but that the discussion of optional films <NUM> and <NUM> still applies.

In some of the present embodiments, the coating <NUM> has a total thickness of less than <NUM>,400Å. This can optionally be the case in any embodiment involving the alloy oxide overcoat film <NUM>'. A base film (e.g., silica at about 100Å) can optionally be added. Additionally or alternatively, a nitride film (e.g., silicon nitride at about 150Å) may be added between the ITO and alloy oxide overcoat films. More will be said of this later.

In one group of embodiments, the alloy oxide overcoat film <NUM>' comprises indium tin oxide. In such cases, the alloy oxide overcoat film <NUM>' can comprise any indium tin oxide film composition described above for indium tin oxide film <NUM>. Thus, in the present embodiment group, the coating <NUM> can include both a first indium tin oxide film (film <NUM>) and a second indium tin oxide film (film <NUM>'). When provided, the second indium tin oxide film is located over, and preferably is in contact with, the first indium tin oxide film. In the present embodiment group, the coating <NUM> preferably includes two, but not more than two, indium tin oxide films.

In the present group of embodiments, the first indium tin oxide film (film <NUM>) preferably is more electrically conductive than the second indium tin oxide film (film <NUM>'). In other words, the second indium tin oxide film preferably has a higher sheet resistance than the first indium tin oxide film. For example, the sheet resistance of the first indium tin oxide film preferably is less than <NUM> ohms per square, more preferably less than <NUM> ohms per square, or even less than <NUM> ohms per square, such as between <NUM> and <NUM> ohms per square. In some cases, it is even less than <NUM> ohms per square, such as about <NUM> ohms per square. In contrast, the sheet resistance of the second indium tin oxide film preferably is greater than <NUM> ohms per square, or greater than <NUM> ohms per square, e.g., between <NUM> and <NUM> ohms per square, such as about <NUM> ohms per square.

When provided, the second indium tin oxide film preferably has a thickness that is different from a thickness of the first indium tin oxide film. This can optionally be the case together with the first ITO film having a lower sheet resistance than the second ITO film, as described and exemplified in the immediately preceding paragraph. In some cases, the second indium tin oxide film is thinner than the first indium tin oxide film. For example, the second indium tin oxide film can optionally have a thickness of less than <NUM>,<NUM>Å, or even less than <NUM>Å, such as about <NUM>Å, while the first indium tin oxide film <NUM> has a thickness of greater than <NUM>,<NUM>Å, such as about <NUM>,<NUM>Å.

In preferred embodiments, the first indium tin oxide film is a suboxide (i.e., is substoichiometric), whereas the second indium tin oxide film is fully oxidized (i.e., stoichiometric). This can optionally be the case in any embodiment of the present group. However, it is not always required. For example, in some cases, both the first and second indium tin oxide films are suboxides, and the second indium tin oxide film is more oxidized than the first indium tin oxide film.

The first and second indium tin oxide films can optionally be devoid of metals other than indium and tin. In some cases, the first and second indium tin oxide films each consist of, or consist essentially of, indium tin oxide.

If desired, the second indium tin oxide film can have the same amounts (or substantially the same amounts) of indium and tin as the first indium tin oxide film. This can optionally be the case in any embodiment of the present group. For example, this can be the case in combination with the first indium tin oxide film being a suboxide and the second indium tin oxide film being fully oxidized, and/or in combination with the first ITO film having lower sheet resistance than the second ITO film, as exemplified herein.

In some cases, the two ITO films of the present embodiment group will have thicknesses and sheet resistances in the following ranges:.

In such cases, the coating <NUM> preferably is devoid of a metal film, or at least does not include a silver film, as noted above. In addition, the first indium tin oxide film can optionally be a suboxide while the second indium tin oxide film is fully oxidized. Furthermore, the second indium tin oxide film can optionally have the same amounts (or substantially the same amounts) of indium and tin as the first indium tin oxide film.

In another group of embodiments, the alloy oxide overcoat film <NUM>' comprises aluminum tin oxide (e.g., is an aluminum tin oxide film). In such cases, the alloy oxide overcoat film <NUM>' can comprise any aluminum tin oxide composition. Thus, in the present embodiment group, the coating <NUM> can include both an indium tin oxide film <NUM> and an aluminum tin oxide film. The aluminum tin oxide film is located over, and preferably is in contact with, the indium tin oxide film <NUM>. Preferably, the aluminum tin oxide film contains both oxidized aluminum and oxidized tin. In some embodiments, the aluminum tin oxide film is devoid of metals other than aluminum and tin. For example, the aluminum tin oxide film can optionally consist of, or consist essentially of, aluminum tin oxide.

In some embodiments of the present group, the aluminum tin oxide film will contain tin at a weight percent (on a metal-only basis) of from <NUM> to <NUM> percent.

In some cases, the indium tin oxide film and the aluminum tin oxide film of the present embodiment group will have thicknesses in the following ranges:.

In such cases, the coating <NUM> preferably is devoid of a metal film, or at least does not include a silver film, as noted above. In addition, the indium tin oxide film preferably is a suboxide while the aluminum tin oxide film is fully oxidized. Furthermore, the aluminum tin oxide film can optionally contain tin at a weight percent (on a metal-only basis) of from <NUM> to <NUM> percent.

In still another group of embodiments, the alloy oxide overcoat film <NUM>' comprises silicon tin oxide (e.g., is a silicon tin oxide film). In such cases, the alloy oxide overcoat film <NUM>' can comprise any silicon tin oxide composition. Thus, the coating <NUM> can include both an indium tin oxide film <NUM> and a silicon tin oxide film. The silicon tin oxide film is located over, and preferably is in contact with, the indium tin oxide film <NUM>. Preferably, the silicon tin oxide film contains both oxidized silicon and oxidized tin. The silicon tin oxide film can optionally be devoid of metals and metalloids other than tin and silicon. For example, the silicon tin oxide film can optionally consist of, or consist essentially of, silicon tin oxide.

In some embodiments of the present group, the silicon tin oxide film will contain tin at a weight percent (on a metal/metalloid-only basis) of from <NUM> to <NUM> percent. In such embodiments, there preferably will be less silicon than tin in the silicon tin oxide film.

In some cases, the indium tin oxide film and the silicon tin oxide film of the present embodiment group will have thicknesses in the following ranges:.

In such cases, the coating <NUM> preferably is devoid of a metal film, or at least does not include any silver film, as noted above. In addition, the indium tin oxide film preferably is a suboxide while the silicon tin oxide film is fully oxidized. Furthermore, the silicon tin oxide film can optionally contain tin at a weight percent (on a metal/metalloid-only basis) of from <NUM> to <NUM> percent.

In yet another group of embodiments, the alloy oxide overcoat film <NUM>' comprises zinc tin oxide (e.g., is a zinc tin oxide film). In such cases, the alloy oxide overcoat film <NUM>' can comprise any zinc tin oxide composition. Thus, the coating <NUM> can include both an indium tin oxide film <NUM> and a zinc tin oxide film. The zinc tin oxide film is located over, and preferably is in contact with, the indium tin oxide film <NUM>. Preferably, the zinc tin oxide film contains both oxidized zinc and oxidized tin. In some such embodiments, the zinc tin oxide film is devoid of metals other than zinc and tin. For example, the zinc tin oxide film can optionally consist of, or consist essentially of, zinc tin oxide.

In some embodiments of the present group, the zinc tin oxide film will contain tin at a weight percent (on a metal-only basis) of from <NUM> to <NUM> percent. In such embodiments, there preferably will be less tin than zinc in the zinc tin oxide film.

In some cases, the indium tin oxide film and the zinc tin oxide film of the present embodiment group will have thicknesses in the following ranges:.

In such cases, the coating <NUM> preferably is devoid of a metal film, or at least does not include any silver film, as noted above. In addition, the indium tin oxide film preferably is a suboxide while the zinc tin oxide film is fully oxidized. Furthermore, the zinc tin oxide film can optionally contain tin at a weight percent (on a metal-only basis) of from <NUM> to <NUM> percent.

Following are descriptions of methods for depositing various embodiments of the present coating <NUM>. These methods do not reflect working examples that have been made and tested, but rather are provided as examples of methods which Applicant predicts can be used to make various embodiments of coating <NUM>.

Following is a non-limiting method for depositing one embodiment of the present coating <NUM> onto a glass substrate. A pair of rotatable ceramic ITO targets, sub-oxide ceramic ITO targets, or metallic indium-tin targets is sputtered in an atmosphere of argon and oxygen while an uncoated glass substrate is conveyed past the activated targets. In this example, the relative weight amounts of the two metals in the sputterable target material is: indium <NUM>%, tin <NUM>%. The resulting indium tin oxide film is deposited so as to have a thickness of about <NUM>,300Å and a sheet resistance of about <NUM> ohms per square. Directly over this first ITO film, a second ITO film is applied by sputtering targets of the same composition (i.e., the same composition as those described above for the first ITO film) in an atmosphere of argon and oxygen. However, the targets used to deposit the second ITO film are sputtered in an atmosphere having a different amount of oxygen (e.g., more oxygen) than the atmosphere used to deposit the first ITO film. The resulting second ITO film is deposited so as to have a thickness of about 800Å and a sheet resistance of about <NUM> ohms per square. A desired heat treatment selected from a variety of known, conventional TCO heat treatment processes is then performed so as to bring the sheet resistance of the first ITO film to about <NUM> ohms per square.

Following is another non-limiting method for depositing certain embodiments of the present coating <NUM> onto a glass substrate. A pair of rotatable ceramic ITO targets, sub-oxide ceramic ITO targets, or metallic indium-tin targets is sputtered in an atmosphere of argon and oxygen while an uncoated glass substrate is conveyed past the activated targets. In this example, the relative weight amounts of the two metals in the sputterable target material is: indium <NUM>%, tin <NUM>%. The resulting indium tin oxide film is deposited so as to have a thickness of about <NUM>,300Å and a sheet resistance of about <NUM> ohms per square. Directly over this ITO film, an aluminum tin oxide film is applied by sputtering metallic aluminum tin targets in an atmosphere of argon and oxygen. In this example, the relative weight amounts of the two metals in the sputterable target material is: <NUM>% tin; <NUM>% aluminum. Useful aluminum tin targets can be obtained commercially from Soleras Advanced Coatings of Deinze, Belgium, or from Materion Advanced Material Group of Buffalo, New York, USA, or from other well-known commercial target suppliers. The resulting aluminum tin oxide film is deposited so as to have a thickness of about 500Å. A desired heat treatment selected from a variety of known, conventional TCO heat treatment processes is then performed so as to bring the sheet resistance of the ITO film to about <NUM> ohms per square.

Following is still another non-limiting method for depositing certain embodiments of the present coating <NUM> onto a glass substrate. A pair of rotatable ceramic ITO targets, or sub-oxide ceramic ITO targets, or metallic indium-tin targets is sputtered in an atmosphere of argon and oxygen while an uncoated glass substrate is conveyed past the activated targets. In this example, the relative weight amounts of the two metals in the sputterable target material is: indium <NUM>%, tin <NUM>%. The resulting indium tin oxide film is deposited so as to have a thickness of about <NUM>,300Å and a sheet resistance of about <NUM> ohms per square. Directly over this ITO film, a silicon tin oxide film is applied by sputtering elemental/metallic silicon tin targets in an atmosphere of argon and oxygen. In this example, the relative weight amounts of the tin and silicon in the sputterable target material is: <NUM>-<NUM>% tin; <NUM>-<NUM>% silicon. Useful silicon tin targets can be obtained commercially from Soleras Advanced Coatings of Deinze, Belgium, or from Materion Advanced Material Group of Buffalo, New York, USA, or from other well-known commercial target suppliers. The resulting silicon tin oxide film is deposited so as to have a thickness of about 500Å. A desired heat treatment selected from a variety of known, conventional TCO heat treatment processes is then performed so as to bring the sheet resistance of the ITO film to about <NUM> ohms per square.

Following is yet another non-limiting method for depositing certain embodiments of the present coating <NUM> onto a glass substrate. A pair of rotatable ceramic ITO targets, or sub-oxide ceramic ITO targets, or metallic indium-tin targets is sputtered in an atmosphere of argon and oxygen while an uncoated glass substrate is conveyed past the activated targets. In this example, the relative weight amounts of the two metals in the sputterable target material is: indium <NUM>%, tin <NUM>%. The resulting indium tin oxide film is deposited so as to have a thickness of about <NUM>,300Å and a sheet resistance of about <NUM> ohms per square. Directly over this ITO film, a zinc tin oxide film is applied by sputtering a pair of targets comprising a compound of zinc and tin in an oxidizing atmosphere while an uncoated glass substrate is conveyed past the activated targets. The oxidizing atmosphere can consist essentially of oxygen (e.g., about <NUM>% O<NUM>) at a pressure of about <NUM>×<NUM>-<NUM> mbar. Alternatively, this atmosphere may comprise argon and oxygen. In this example, the relative weight amounts of the two metals in the sputterable material of the targets is: zinc <NUM>%; tin <NUM>%. The resulting zinc tin oxide film is deposited so as to have a thickness of about 500Å. A desired heat treatment selected from a variety of known, conventional TCO heat treatment processes is then performed so as to bring the sheet resistance of the ITO film to about <NUM> ohms per square.

Claim 1:
A multiple-pane insulating glazing unit having a between-pane space and two opposed external pane surfaces, a desired one of the two external pane surfaces bearing a coating comprising both an indium tin oxide film and an aluminum tin oxide film, the aluminum tin oxide film being located over the indium tin oxide film, the aluminum tin oxide film being in contact with the indium tin oxide film.