WO2011071737A2

WO2011071737A2 - Solar control single low-e series with low visible reflectance

Info

Publication number: WO2011071737A2
Application number: PCT/US2010/058662
Authority: WO
Inventors: James G. Rietzel; Steven J. Nadel; Christoph Braatz
Original assignee: Applied Materials, Inc.
Priority date: 2009-12-10
Filing date: 2010-12-02
Publication date: 2011-06-16
Also published as: WO2011071737A3; TW201139313A

Abstract

Low emissivity structures and methods are provided for reducing solar or visible transmissions with reduced reflectivity, such as for architectural glass. Reflectivity may be less than about 20% when visible transmissions are between about 20-70%. An absorption layer may be provided on one and/or both sides of the silver layer, such that absorption may be increased without excessively thickening other layers. In one embodiment, a low-E structure with reduced reflectance may comprise a glass substrate, a bottom dielectric, an absorption layer of a metal or metal nitride, a silver layer, a protective layer of a metal or metal nitride, and a top dielectric. The bottom absorption layer may have a thickness between about 5-75 angstroms.

Description

SOLAR CONTROL SINGLE LOW-E SERIES

WITH LOW VISIBLE REFLECTANCE

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] Embodiments of the present invention generally relate to configurations of low-emissivity coatings, and methods and systems for making the same.

Description of the Related Art

[0002] In order to build energy efficient homes and offices, windows are needed that reduce energy losses and that control solar transmissions. Modern windows may be made with low emittance properties by coating a transparent substrate, such as architectural glass, with a series of thin films. Low-emissivity glass or coatings are referred to as "low-E."

[0003] The arrangement of thin film layers, along with their compositions and thicknesses, must be carefully selected to obtain the properties desired. For example, the coating stack may allow transmission of visible light (e.g., wavelengths of about 380-750 nm), while inhibiting transmission of infrared (IR) energy (e.g., wavelengths greater than about 700-750 nm). Further, the desired properties may change depending upon the intended use. In regions that receive lots of sunlight, windows are needed that control the transmission of sunlight. For some applications, it is desirable to control transmissions to ranges generally between about 20-60 percent of visible light.

[0004] Conventionally, low-E coating stacks reduce solar energy transmission by using a thin metallic layer with high reflectivity and low emissivity, such as silver (Ag). To reduce sunlight transmitted through the glass, the thickness of the silver layer may be increased. But a major disadvantage of this approach is that increasing the thickness of the silver layer increases the reflectance on the uncoated glass side that faces outside the building. High reflectivity results in an appearance like a semi-transparent mirror, which is very undesirable for buildings. Some regions, such as Singapore, have even passed legislation prohibiting the use of high reflecting products in commercial buildings.

[0005] One approach to reducing the transmission of sunlight with less reflectivity is to increase the thickness of a protective layer that is conventionally placed over the silver layer. Typically in low-E coating stacks, a protective layer is deposited over the silver layer, so that the silver does not react with deposition gases when a top dielectric layer is added. Dielectric materials, such as transparent oxides or nitrides, may be used for top layers to provide scratch resistance. For example, a conventional low-E coating stack deposited onto a glass substrate would include: a bottom dielectric layer, a silver layer, a protective layer, and a top dielectric layer.

[0006] Materials may be used in the protective layer that also have absorption properties in sunlight, such as a nickel chromium oxide or nickel chromium. Thus, conventional approaches to reducing the transmission of sunlight with less reflectivity employ an absorption material as the protective layer and increase the thickness of the protective layer to further reduce visible transmissions. But in order to achieve low visible transmission of sunlight, very thick absorption layers are required. For example, to reduce solar transmission below 50 percent, this approach would require a nickel chromium oxide layer with a thickness greater than about 100 angstroms. Depositing such a thick nickel chromium oxide layer requires either adding more deposition sources or slowing down the process speeds to allow a single deposition source to run at powers which do not damage the deposition target or the coating system. This adds significant costs and inefficiencies to the deposition process.

[0007] Further, the reflectance levels achieved by this approach are still too high for some applications. A conventional low-E stack that achieves 60 percent visible transmission has a glass-side reflectance level of about 10-20 percent. When the visible transmission is reduced to 50 percent, the reflectance level increases to over 35 percent. [0008] Accordingly, there is a need for improved low-E coating stacks and deposition methods and systems to produce windows that may reduce the transmission of sunlight with less reflectance. There is also a need for a coating stack that achieves these purposes with thinner layers. There is further a need for a coating stack that may achieve these purposes with a single series of layers. Moreover, there is a need for methods and systems to deposit such coating stacks more efficiently. There is also a need for a family of coating stack designs that achieves these purposes with the minimal addition of new materials or layers, to allow for the most efficient layout of a coating system.

SUMMARY OF THE INVENTION

[0009] Embodiments disclosed herein generally provide improved coating stacks and production methods and systems that allow for reducing solar / visible transmissions with reduced reflectivity. The inventors have discovered that adding a thin absorption layer below a reflective low-E metal layer, such as a silver layer, allows coating stacks to be developed with thinner layers that reduce visible transmissions with dramatically less reflectivity. Thus, multiple benefits are achieved by reducing reflectivity while employing thinner film layers and more efficient process systems. In one embodiment, visible transmissions may be reduced to ranges as low as about 20 percent, while reflectivity is reduced to about 20 percent or less.

[0010] In other embodiments, the thin absorption layer below the reflective layer can be combined with another thin absorption layer that splits the top, protective dielectric layer. The additional benefit of the second absorber layer is that by adjusting the thicknesses of the bottom and top dielectric layers, a variety of strong colored coatings (such as blue, green, gold) can made with low transmission and controlled reflectance. This provides an architect a wide range of design colors while achieving the required solar, and visible (glare) control with controlled external reflectance.

[0011 ] In one embodiment, a low-emissivity structure is provided for increased solar control comprising: a substrate, a bottom dielectric layer positioned above of the substrate, a bottom absorption layer positioned above the bottom dielectric layer, a reflective layer positioned above the bottom absorption layer, a protective layer positioned above the silver layer, and an upper dielectric layer positioned above the protective layer. Series of layers may also be stacked, such as in a double or triple low-emissivity coating stacks.

[0012] The low-E structure may have a reflectivity less than about 20%. The low-E structure may have a range of visible transmission less than or equal to about 70%, or 60%, or 50%, or 40%. The bottom absorption layer may comprise a metal or metal nitride. The metal component may be composed of Cr, Ti or various alloys containing these metals such as stainless steel or various alloys of nickel and chromium such as 80% nickel and 20% chromium. In one embodiment, the bottom absorption layer is Cr metal or Cr deposited in nitrogen to form chromium nitride. The bottom absorption layer may have a thickness between about 10 to 100 angstroms, or about 15 to 75 angstroms, or about 15 to 50 angstroms, or another desired range. The protective layer may also comprise at least one of the same types of metal as in the bottom absorption layer. The reflective layer may comprise silver, and may have a thickness of about 1 10 angstroms or less.

[0013] In another embodiment, a method is provided of depositing a low- emissivity structure for increased solar control comprising: providing a substrate, depositing a bottom dielectric layer above the substrate, depositing a bottom absorption layer above the bottom dielectric layer, depositing a silver layer above the absorption layer, depositing a protective layer above the silver layer, and depositing an upper dielectric layer above the protective layer. Series of layers may also be stacked, such as in a double or triple low-emissivity coating stack.

[0014] Methods may also produce a low emissivity structure with a reflectivity less than about 20%. The low-emissivity structure may also have a range of visible transmission less than or equal to about 70%, or 60%, or 50%, or 40%. The bottom absorption layer may comprise a metal or a metal nitride. The metal nitride may comprise nitrogen and chromium, or an alloy of 80% nickel and 20 % chromium. The bottom absorption layer may have a thickness between about 10 to 100 angstroms, or about 15 to 75 angstroms, or about 15 to 50 angstroms, or another desired range. The protective layer may also comprise at least one of the same types of metal as in the bottom absorption layer. The silver layer may have a thickness of about 1 10 angstroms or less. Further, the protective layer may comprise at least one of the same types of metal as in the bottom absorption layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended figure. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0016] Figure 1 depicts a low-emissivity structure according to one embodiment of the invention.

[0017] Figure 2 depicts a simplified version of a PVD system with a planar magnetron.

[0018] Figure 3 depicts an example of a color chart, with respective colors labeled, which may be used to describe reflected light measurements.

[0019] Figure 4 depicts a low-emissivity structure according to another embodiment of the invention.

[0020] Figure 5 depicts a stacked low-emissivity structure according to another embodiment of the invention.

DETAILED DESCRIPTION

[0021 ] Embodiments of the present invention discussed herein generally provide improved coating stacks and production methods and systems for producing low- emissivity structures with a series of thin layers that reduce solar and/or visible transmissions with less reflectivity than conventional coating stacks. Embodiments discussed herein achieve these results through use of an absorption layer beneath a reflective layer, either alone or in combination with a 2nd absorption layer splitting the top dielectric layer, as described more fully below.

[0022] Figure 1 depicts a low-emissivity structure 1 , according to one embodiment of the invention. In Figure 1 , a series of thin film layers are deposited on a substrate 2. The series of thin film layers comprise: a bottom dielectric layer 3, an absorption layer 4, a reflective layer 5, a protective layer 6, and a top dielectric layer 7. The absorption layer 4 may be alternatively located in the middle of the top dielectric layer 7. In other embodiments, at least two absorption layers 4 may alternatively may be utilized, for example, at least one absorption layer between the reflectively layer and bottom dielectric layer and at least one absorption layer splitting the top dielectric layer. Reflective layer 5 preferably comprises silver (Ag). Low-E structure 1 may comprise architectural glass, such as used to make windows in homes or commercial buildings. It is to be understood that the invention may be applied to other applications as well.

[0023] For window applications, substrate 2 may comprise a transparent material, such as soda lime glass. A bottom dielectric layer 3 may be deposited on the substrate 2. For example, when soda lime glass is used for substrate 2, the bottom dielectric layer 3 may provide a diffusion barrier to contain contaminants in the glass such as sodium. The dielectric material may be a transparent oxide or nitride, such as tin oxide, zinc oxide or silicon nitride. When nitrides are used, adding small amounts of oxygen has been found to reduce thin film stress and inhibit cracking upon heating, while maintaining deposition speeds. For example, oxygen may be used in the deposition mixture at about 20% or less by volume. The dielectric material may be selected to have a high index of refraction, to reduce reflection. In some embodiments, an index of refraction may be selected from a range of about 1 .8 - 2.5 based on the optical requirements for the stack. A good index of refraction may be about 2.0. Materials may also be mixed to optimize the desired properties. Materials may also be selected based on desired properties of adhesion, stress, chemical and mechanical durability, hardness, temperability, or other desired attributes.

[0024] Absorption layer may comprise a suitable metal, metal alloy or metal nitride that exhibits good light absorption and low reflectance. One suitable material is a chromium-containing metal nitride. Chromium, chromium nitride, nickel, nickel- chromium, titanium or stainless steel may also be used for the component metal or metal nitride. One embodiment utilizes a metal alloy of about 80% nickel and about 20% chromium by weight. Previous methods controlled absorption (and thus reflectivity) by using the protective layer (deposited over the reflective layer) to also serve as an absorption layer. However, this required increasing the thickness of the protective layer to be over about 100 angstroms. The inventors have discovered that absorption can be better controlled with less material by adding an absorption layer between the substrate 2 and the reflective layer 5. For example, absorption layer may be about 50 angstroms or less. In some embodiments, absorption layer may be deposited at a thickness ranging from about 5 - 15 angstroms. Additional examples are provided below.

[0025] Absorption layer may also be deposited by sputtering in nitrogen. Utilizing a nitride compound requires thicker layers to provide the desired absorption, but results in even lower reflectivities. Small amounts of oxygen may also be added to the bottom absorption layer, for example if the material is to be tempered.

[0026] A thin absorption layer of about 10-100 angstroms has been found to provide a range of visible transmissions between about 30-70%. For this range, reflectivity remains less than about 20%. In one embodiment, the thicknesses of additional absorption layer 4 may be between about 15-75 angstroms, or alternatively, between about 15-50 angstroms, depending on the desired transmission range.

[0027] In some embodiments, transmission levels may be adjusted by only altering the thickness of additional absorption layer 4. This allows for greater process control, flexibility and efficiency. Entire families of coating stacks may be deposited that control solar transmissions in a range of about 20-70%, by varying the thickness or composition of absorption layer. Multiple products may be made with the same target configuration. Such variation may also allow variation in the appearance or reflected color of the coating, further providing a variety of design options to architects and designers.

[0028] Reflective layer 5 determines the solar transmission. Silver is a suitable material that provides low emittance and high reflectivity in the solar and long wavelength region. Conventional approaches to reducing solar transmission by thickening a silver layer cause undesired levels of reflectance, for example over about 35%. One embodiment of the invention provides a reflective layer 5 of silver having a thickness of about 1 10 angstroms or below.

[0029] Above reflective layer 5, a protective layer 6 is deposited. Protective layer 6 provides a barrier to protect materials such as silver in reflective layer 5 during deposition of a top dielectric layer 7. Protective layer 6 may be very thin, such as a thickness from about 1 - 50 angstroms. It is advantageous for protective layer 6 to stick well to top dielectric layer 7. For example, nickel-chromium alloys may be used for dielectric materials of silicon nitride, silicon oxide or silicon oxynitride. One embodiment utilizes a metal alloy of about 80% nickel and about 20% chromium by weight. The metal used in protective layer 6 may react with deposition gases used to deposit top dielectric layer 7 and thus form metal oxides or nitrides in protective layer 6. Small amounts of oxygen may also be added if the material is to be tempered. Protective layer 6 also may absorb solar transmission. The protective layer 6 may be made from the same or similar materials as absorption layer 4, which provides further efficiencies to the process.

[0030] Top dielectric layer 7 may be a transparent oxide or nitride, such as tin oxide, zinc oxide or silicon nitride. Top dielectric layer 7 may also comprise two or more dielectric materials (or multiple layers) deposited on top of each other. Silicon nitride is a suitable material because it is mechanically and corrosively resistant. [0031 ] The series of layers provided herein may be repeated in multiple stacks, such as in double or triple low-emissivity coating stacks. Additionally, materials may be mixed or deposited in sequence for layers such as top dielectric layer 7. For example, a tin oxide may be deposited on top of protective layer 6, followed by a scratch resistant layer of silicon nitride. Further, adding small amounts of oxygen to a nitride, such as silicon nitride, has been found to reduce thin film stress and inhibit cracking, while maintaining deposition speeds.

[0032] In another embodiment, a suitable magnetron may be set up in a system to manufacture low emissivity coatings. The magnetron may be a planar or rotatable (cylindrical) magnetron. Each magnetron may have a target for sputter depositing a film layer. One target may be used for depositing absorption layer 4, one for depositing reflective layer 5, and one for depositing protective layer 6. This system may be provided by using individual chambers or an in-line system.

[0033] Figure 2 shows a simplified version of a PVD system 1 1 with a magnetron 12, for purposes of explanation. One or more magnetrons 12 may be used in PVD systems for depositing thin films on substrates. PVD systems may use various configurations, such as a chamber or an in-line arrangement. In Figure 2, a substrate 14 is positioned on a substrate support 15. A sputtering target 13 is provided, which may be substantially planar or cylindrical. The sputtering target 13 may be made of or coated by a material to be sputtered or deposited on substrate 14. For example, sputtering target 13 may be made from a ceramic material with an outer layer or coating of a metallic or semiconductor material to be sputtered during processing.

[0034] Planar magnetron 12 may be positioned above sputtering target 13. During the deposition process, a gas is introduced through gas inlet 16 into deposition enclosure 17. A plasma may be ignited, such as by an RF or DC electromagnetic field. The magnetron 12 produces a magnetic field for containing or increasing the density of a plasma (excited ions) near the sputtering target's 13 surface. Ions from the plasma may then bombard the sputtering target 13 and sputter atoms or particles from the sputtering target 13. Magnetic structures that comprise the magnetron may be moved, such as to maintain an even erosion profile. An exhaust outlet 18 is also provided.

[0035] Atoms or particles sputtered from the sputtering target 13 impact and deposit on the substrate 14. The gas may also be selected to react with the sputtered target material ions and/or atoms to form molecules of a desired compound on the substrate 14. Reactions may take place at the sputtering target 13, at the substrate 14 or in a plasma or vapor phase region. A non reactive gas, such as Argon, may also be used to slightly enhance deposition rates. For example, sputtering a silicon containing layer may be done with a silicon coated target in a mixture of 50% Ar / 50% N₂ to provide a slightly enhanced deposition rate of silicon nitride, relative to pure N₂ sputtering, while not risking depositing a layer that is more like the target material than the desired reacted compound. Silicon containing layers may also be deposited with cylindrical magnetrons, using a cylindrical target with a magnetic structure inside it.

[0036] When absorption layer 4 and protective layer 6 comprise the same material, the same type of planar targets 13 may be used. For example, a planar target comprising a nickel-chromium alloy may be used to sputter absorption layer 4. A planar target comprising silver may be used to sputter reflective layer 5. And another planar target comprising a nickel-chromium alloy may be used to sputter protective layer 6.

Examples

[0037] Example 1 . A transmission level of about 40% was obtained on a glass substrate with a bottom dielectric layer of 175 angstroms of tin oxide, an additional absorption layer of 50 angstroms of chromium, a silver layer of 105 angstroms, a protective layer of nickel chromium of a small amount referred to as a whisp, and top dielectric layers of 210 angstroms of tin oxide followed by 210 angstroms of silicon nitride. A whisp represents a thickness in a range of about 5 to about 15 angstroms.

[0038] Average cross coater measurements are provided in Table 1 below. Rf stands for the amount of reflection measured on the coating or "film" side of the glass. Rg stands for the amount of reflection measured on the uncoated or "glass" side of the glass. The symbols "a*" and "b*" are coordinates on an x-y axis that measures color. An example color chart is shown in Figure 3, with respective colors labeled. Colors are designated by the x-y coordinates on the chart. Yellow is designated with "+ b*." Red is designated as "+ a*." Blue is designated as "- b*." And green is designated as "- a*." By way of example, points A and B in Figure 3 illustrate colors with different hues.

Table 1

[0039] Example 2. A transmission level of about 52% was obtained on a glass substrate (5 mm) with a bottom dielectric layer of 400 angstroms of tin oxide, an additional absorption layer of 35 angstroms of chromium, a silver layer of 1 10 angstroms, a protective layer of a whisp of nickel chromium, and top dielectric layers of 250 angstroms of tin oxide followed by 150 angstroms of silicon nitride. Average cross coater measurements are provided in Table 2 below.

Table 2

[0040] Example 3. A transmission level of about 59% was obtained on a glass substrate with a bottom dielectric layer of 400 angstroms of tin oxide, an additional absorption layer of 25 angstroms of chromium, a silver layer of 105 angstroms, a protective layer of a whisp of nickel chromium, and top dielectric layers of 265 angstroms of tin oxide followed by 165 angstroms of silicon nitride. Average cross coater measurements are provided in Table 3 below. Table 3

[0041] Example 4. A transmission level of about 69% was obtained on a glass substrate with a bottom dielectric layer of 400 angstroms of tin oxide, an additional absorption layer of 15 angstroms of chromium, a silver layer of 105 angstroms, a protective layer of a whisp of nickel chromium, and top dielectric layers of 265 angstroms of tin oxide followed by 165 angstroms of silicon nitride. Average cross coater measurements are provided in Table 4 below.

Table 4

[0042] Figure 4 depicts a low-emissivity structure 400 according to another embodiment of the invention. The low-emissivity structure 400 comprises a series of thin film layers are deposited on a substrate 402. The substrate 402 may be the same or similar to the substrate 2 as described above. The low-emissivity structure 400 includes a bottom dielectric layer 404, an optional reflection reducing layer 406, a lower absorption layer 408, a reflective layer 410, a protective layer 412, a middle dielectric layer 414, an upper absorption layer 416 and a top dielectric layer 418. The optional reflection reducing layer 406 may be Ti0₂ or other suitable material that counteracts the reflection generated by the reflective layer 410. The use of the optional reflection reducing layer 406 allows for reduced sunlight transmittance by allowing the use of a thicker reflective layer 410 without a corresponding increase in reflectance as would be realized in conventional film stacks.

[0043] The bottom dielectric layer 404, reflective layer 410, protective layer 412 may be fabricated from materials as described above with reference to the embodiment of Figure 1 . The upper and lower absorption layers may comprise a suitable metal, metal alloy or metal nitride that exhibits good light absorption and low reflectance, such as the materials described above with reference to the absorption layer 4 of Figure 1 . Table 5 provides examples of thickness ranges in nm for the films of the structure 400. For the absorbing layer having a bottom value of "0" indicates that one or more of the absorbing layers may be used (i.e., either bottom absorbing layer 408 or top absorbing layer 416 alone, or with both absorbing layers together).

Table 5

[0044] The top absorption layer disposed between the middle and top dielectric layer produces the same advantageous low transmission and low reflectivity benefits of embodiments described above, and advantageously provides the ability to produce strong colors, such as gold, blue and green, which are desirable in Asian- Pacific markets, by tuning the relative thicknesses of the constituent layers of the structure 400. For example, a gold color may be obtained by utilizing about a 10nm lower dielectric layer 404, about a 10nm reflection reducing layer 406, about a 7nm lower absorption layer 408, about a 13nm reflective layer 410, about a 3nm protective layer 412, about a 67nm middle dielectric layer 414, about a 7nm upper absorption layer 416 and about a 10nm top dielectric layer 418. The strength of the gold color may be increased by increasing the thickness of the reflection reducing layer 406 and top dielectric layer 418, while reducing the thickness of the lower absorption layer 408, the reflective layer 410, the middle dielectric layer 414, and the upper absorption layer 416. In some embodiments, the thickness of the upper absorption layer 416 may be reduced to about zero or even eliminated to produce a strong gold color. [0045] In another example, a blue color may be obtained by utilizing about a 15nm lower dielectric layer 404, about a 35nm reflection reducing layer 406, about a 10.5nm lower absorption layer 408, about a 10nm reflective layer 410, about a 4nm protective layer 412, about a 40nm middle dielectric layer 414, about a 10.5nm upper absorption layer 416 and about a 30nm top dielectric layer 418. The strength of the blue color may be increased by reducing the thickness of the lower absorption layer 408 and the upper absorption layer 416.

[0046] In another example, a green color may be obtained by utilizing about a 15nm lower dielectric layer 404, about a 65nm reflection reducing layer 406, about a 9.5nm lower absorption layer 408, about a 10nm reflective layer 410, about a 4nm protective layer 412, about a 30nm middle dielectric layer 414, about a 9.5nm upper absorption layer 416 and about a 30nm top dielectric layer 418. The strength of the green color may be increased by reducing the thickness of the lower absorption layer 408 and the upper absorption layer 416.

[0047] Figure 5 depicts a stacked low-emissivity structure 500 according to another embodiment of the invention. The stacked low-emissivity structure 500 comprises a base film stack 502 deposited on a substrate 402, with one or more capping film stacks 504 deposited on the base film stack 502. The base film stack 502 maybe configured as any of the structures described above, for example as the structure 1 or structure 400. The capping film stack 504 includes an optional capping base dielectric layer 505, a capping reflective layer 506, a capping protective layer 508, and a capping dielectric layer 510. The optional capping base dielectric layer 505 is utilized to adjust the total thickness of the internal dielectric layers (414/418) of the structure 500. Generally, when utilizing multiple stacks, the inner dielectric layers are generally about 1 -1/2 to 2 times as thick as the bottom dielectric layer 404 (next to glass) and the top (protective) capping dielectric layer 510. Thus, in instances wherein the layers 414 and/or 418 are not 1 -1/2 to 2 times as thick as the bottom dielectric layer 404, an appropriate thickness of capping base dielectric layer 505 may be utilized to compensate of for the difference in the thickness. This base layer 505, when combined with the top layer (414 or 418) of the previous stack, provides a thick middle dielectric layer which is 1 -1 /2 to 2 times as thick as the bottom dielectric layer 404.

[0048] Optionally, the capping dielectric layer 510 may be configured as a middle dielectric layer and top dielectric layer sandwiching an absorption layer as described with reference to Figure 4. The capping reflective layer 506, capping protective layer 508, and the capping dielectric layer 510 may be fabricated from materials as described above with reference to the embodiment of Figure 1 . The capping reflective layer 506 is deposited in the top dielectric layer 418 of the base film stack 502, or on the capping dielectric layer 510 of the underlying capping film stack 504. Table 6 provides examples of thickness ranges in nm for the films of the capping film stack 504.

Table 6

[0049] The stacked low-emissivity structure 500 provides the ability to control solar transmission, resulting reduced heat load on buildings and lower air conditioning costs. The stacked low-emissivity structure 500 advantageously provides the ability to reach even lower transmission values with very low outside reflectance as compared to conventional coated glass. In all of the embodiments described above, the structures may be toughen by tempering. The tempering process may be or traditional low-emissivity tempering process as known or any other suitable tempering process.

[0050] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

Claims:

1 . A low-emissivity structure for increased solar control comprising:

a substrate;

a bottom dielectric layer positioned above of the substrate;

a bottom absorption layer positioned above the bottom dielectric layer; a reflective layer positioned above the bottom absorption layer;

a protective layer positioned above the silver layer; and

an upper dielectric layer positioned above the protective layer.

2. The low-emissivity structure of claim 1 , wherein the low emissivity structure has a reflectivity less than about 20%.

3. The low-emissivity structure of claim 2, wherein the bottom absorption layer comprises a metal or metal nitride.

4. The low-emissivity structure of claim 3, wherein the bottom absorption layer comprises a metal nitride comprising nitrogen and chromium or an alloy of nickel and chromium.

5. The low-emissivity structure of claim 3, wherein the bottom absorption layer has a thickness between about 5 to 100 angstroms.

6. The low-emissivity structure of claim 3, wherein the low-emissivity structure has a range of visible transmission less than or equal to about 70%.

7. The low-emissivity structure of claim 6, wherein the low-emissivity structure has a range of visible transmission less than or equal to about 50%.

8. The low-emissivity structure of claim 6, wherein the protective layer comprises at least one of the same type of metal as in the bottom absorption layer.

9. The low-emissivity structure of claim 6, wherein the reflective layer comprises silver, and wherein the reflective layer has a thickness of about 1 10 angstroms or less.

10. The low-emissivity structure of claim 1 , wherein the low emissivity structure is temperable.

1 1 . A method of depositing a low-emissivity structure for increased solar control comprising:

providing a substrate;

depositing a bottom dielectric layer above the substrate;

depositing a bottom absorption layer above the bottom dielectric layer;

depositing a silver layer above the absorption layer;

depositing a protective layer above the silver layer; and

depositing an upper dielectric layer above the protective layer.

12. The method of depositing a low-emissivity structure of claim 1 1 , wherein the low emissivity structure has a reflectivity less than about 70%.

13. The method of depositing a low-emissivity structure of claim 1 1 , wherein the bottom absorption layer comprises a metal or metal nitride.

14. The method of depositing a low-emissivity structure of claim 1 1 , wherein the bottom absorption layer comprises a metal nitride comprises nitrogen and chromium or an alloy of nickel and chromium.

15. The method of depositing a low-emissivity structure of claim 1 1 further comprising depositing a second absorption layer above the silver layer.

16. The method of depositing a low-emissivity structure of claim 1 1 further comprising:

depositing a middle dielectric layer above the silver layer; and depositing a second absorption between middle dielectric layer and the top dielectric layer.