`
`(cid:44)(cid:49)(cid:55)(cid:40)(cid:47) EXHIBIT 10(cid:22)(cid:23)
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`Patent Application Publication Nov. 15, 2001 Sheet 1 0f 3
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`US 2001/0041252 A1
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`Page 2 of 8
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`Patent Application Publication Nov. 15, 2001 Sheet 2 0f 3
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`US 2001/0041252 A1
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`Patent Application Publication Nov. 15, 2001 Sheet 3 0f 3
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`US 2001/0041252 A1
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`Nov. 15, 2001
`
`LOW-EMISSIVITY GLASS COATINGS HAVING A
`LAYER OF NITRIDED NICHROME AND
`METHODS OF MAKING SAME
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`
`[0001] This application is based on, and claims domestic
`priority benefits under 35 USC §119(e) from, US. Provi—
`sional Application No. 60/187,039 filed on Mar. 6, 2000, the
`entire content of which is expressly incorporated hereinto by
`reference.
`
`FIELD OF THE INVENTION
`
`[0002] The present invention relates generally to coatings
`for glass substrates. More specifically, the present invention
`relates to glass substrate coatings which exhibit low emis-
`sivity (so-called “low-E” coatings) and substantially no
`color characteristics.
`
`BACKGROUND AND SUMMARY OF THE
`INVENTION
`
`[0003] Low-E coatings for glass are well known. In this
`regard, commonly owned US. Pat. Nos, 5,344,718, 5,425,
`861, 5,770,321, 5,800,933 (the entire content of each being
`incorporated expressly herein by reference) disclose coat—
`ings formed of a multiple layer coating “system”. Generally,
`such conventional multiple layer low-E glass coatings have
`a layer of a transparent dielectric material (e.g., TiOz, Bi203,
`PbO or mixtures thereof) adjacent the glass substrate and a
`sequence of multiple layers of, for example, Si3N4, nickel
`(Ni), nichrome (NizCr), nitrided nichrome (NiCrN) and/or
`silver (Ag). These conventional low—E coatings are, more—
`over, heat—treatableithat is, the coating is capable of being
`subjected to the elevated temperatures associated with con-
`ventional tempering, bending, heat-strengthening or heat-
`sealing processes without significantly adversely affecting
`its desirable characteristics.
`
`low-E coating systems
`[0004] While the conventional
`disclosed in the above-cited US. patents are satisfactory,
`there exists a continual need to improve various properties
`of low—E coating systems generally. For example, continued
`improvements in the durability and/or color (or more accu-
`rately, lack of color) characteristics in low-E glass coatings
`are desired. Improvements in such characteristics are impor-
`tant to ensure that the coatings retain their low—E property
`for prolonged periods of time (even after being subjected to
`potentially abrasive environment encountered during the
`manufacturing process—e.g.,
`the washing and cutting of
`glass articles having such low-E coatings) and have the
`desired light transmission properties. It is toward fulfilling
`such needs that the present invention is directed.
`
`invention is embodied in
`the present
`[0005] Broadly,
`low—E glass coated glass articles comprised of a glass
`substrate and a multiple layer coating on a surface of the
`glass substrate, wherein the coating includes a layer of a
`transparent dielectric material adjacent the surface of the
`glass substrate, a layer of nitrided nichrome, and a layer of
`silver which is sputter coated onto the glass substrate in a
`nitrogen-containing atmosphere. Most preferably, the coat-
`ing further includes a layer of silicon oxynitride interposed
`between the layer of dielectric material and the layer of
`nitrided nichrome.
`
`[0006] These and other aspects and advantages will
`become more apparent after careful consideration is given to
`the following detailed description of the preferred exem—
`plary embodiments thereof.
`
`BRIEF DESCRIPTION OF THE
`ACCOMPANYING DRAWINGS
`
`[0007] Reference will hereinafter be made to the accom—
`panying drawings, wherein like reference numerals through-
`out the various FIGURES denote like structural elements,
`and wherein;
`
`[0008] FIG. 1 is a is a greatly enlarged cross—sectional
`schematic representation of a surface-coated glass article of
`this invention which includes a glass substrate and a mul—
`tiple layer low-E coating system coated on a surface of the
`glass substrate;
`
`[0009] FIG. 2 is a graph of % Transmission and transmit-
`ted a*, b* Values for glass articles containing a low—E
`coating of this invention compared against other coatings
`not within the scope of this invention, and
`
`[0010] FIG. 3 is a gaph showing the concentration, in
`atomic percent
`(at. %), of constituents of a SiAlOXNy
`coating on a Si substrate according to Example III, Test
`Sample 3 below versus the depth of the coating in Ang—
`stroms (A).
`
`|)L"l‘All.L“|) DESCRIPTION ()l" THE
`INVENTION
`
`[0011] Accompanying FIG. 1 depicts in a schematic fash-
`ion one particularly preferred embodiment of the present
`invention. In this regard, the multiple layer low-E coating of
`the present invention will necessarily be applied onto a glass
`substrate 10 which is, in and of itself, highly conventional.
`Specifically, the glass substrate 10 is most preferably made
`by a conventional float process and is thus colloquially
`known as “float glass”. Typical thicknesses of such float
`glass may be from about 2 mm to about 6 mm, but other
`glass thicknesses may be employed for purposes of the
`present invention. The composition of the glass forming the
`substrate 10 is not critical, but typically the glass substrate
`will be formed of one of the soda-lime-silica types of glass
`well known to those in this art.
`
`[0012] The process and apparatus used to form the various
`layers comprising the low—E coating of the present invention
`may be a conventional multi-chamber (multi-target) sputter-
`coating system such as that disclosed generally in US. Pat.
`No. 5,344,718 (the entire content of which is incorporated
`expressly herein by reference). One particularly preferred
`sputter-coating system is commercially available from
`Airco, Inc. As is well known,
`the glass substrate 10 is
`advanced sequentially through the contiguous chambers or
`zones which have respective atmospheres to form sputter-
`coating layers of desired constituency and thickness.
`
`[0013] As depicted in FIG. 1, one particularly preferred
`low-E coating may be formed of the following layers and
`layer thicknesses (identified sequentially from adjacent the
`glass substrate 10 toward the outside):
`
`layer Constituent
`(u)
`transparent dielectric
`(a)
`silicon nitride (Si3N4)
`(by)
`nitrided nichrome (NiCrN)
`(c)
`silver (Ag)1
`
`Thickness
`Range (A)
`
`about 100—200
`about 25—200
`about 2740
`about 100—200
`
`Thickness
`Preferred (A)
`about 125
`about 125
`about 10
`about 145
`
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`US 2001/0041252 A1
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`Nov. 15, 2001
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`—continued
`
`Layer Constituent
`
`Thickness
`Range (A)
`
`Thickness“
`Preferred (A)
`
`(d)
`(e)
`
`nitrided nichrome (NiCrN)
`silicon nitride (Si3N4)
`
`about 2—40
`about 350—600
`
`about 20
`about 480
`
`1Silver is sputter-coated onto the glass substrate surface in a nitrogen-con-
`taining atmosphere.
`
`[0014] The undercoat layer (u) in FIG. 1 is selected so it
`has an index of refraction at 550 nm wavelength of about 2.5
`to about 2.6, and preferably about 2.52. Preferably,
`the
`undercoat layer (u) includes at least one transparent dielec—
`tric selected from TiOz, BiO3, PbO and mixtures thereof.
`TiOZ is especially preferred.
`[0015] The low-E coated glass article embodying the
`present invention will exhibit a relatively high light trans—
`missivity (i.e., greater than about 72%) and will have
`acceptable a* and b* transmission of between about —2.0 to
`—4.0 (preferably about —3.0)
`for
`a* transmission, and
`between about —0.5 to about 1.5 (preferably about 0.5) for
`b* transmission.
`
`[0016] According to the present invention, nitrogen gas is
`used in the sputtering zone to form the NiCr layer and the Ag
`layer. Most preferably, the gas will be a mixture of nitrogen
`and argon, wherein less than about 25% of the gas is
`nitrogen and greater than about 75% of the gas is argon.
`Most preferably, nitrogen is present in the sputter zones
`using nichrome (i.e., 80% Ni/20% Cr) and silver targets to
`form the nitrided nichrome and silver layers, respectively, in
`an amount between about 5% to about 25%. A ratio of argon
`to nitrogen of 85:15 is especially preferred in each such
`sputtering zone.
`[0017] Advantageously, oxygen is employed in the sput-
`tering zone during the formation of layer (a) so as to form
`a silicon oxynitride. Most preferably, the silicon oxynitride
`layer (a) is sputter—coated in a gaseous atmosphere com—
`prised of nitrogen, oxygen and argon, wherein at
`least
`between about 5% to about 50%, most preferably about
`10%, of the gas is oxygen. A particularly preferred atmo-
`sphere for sputter—coating the silicon oxynitride layer (a) is
`about 30% N2, about 10% ()2 and about 60% Ar2.
`[0018] According to the present invention,
`the rate at
`which oxygen gas is incorporated into a silicon nitride layer
`(a) during formation can be varied so as to obtain a silicon
`oxynitride layer having an oxygen gradient. By the term
`“oxygen gradient” is meant that the concentration of oxygen
`(atomic percent (at. %)) decreases from one location in a
`silicon oxynitride layer to another location at a different
`depth in that same layer. If present, the oxygen gradient is
`most preferably such that the greater amount of oxygen
`concentration is nearer the bottom of the layer (i.e., towards
`the glass substrate) with the lesser amount of oxygen con-
`centration being nearer the top of the layer (i.e., away from
`the glass substrate). In terms of the decrease in oxygen
`concentration, the oxygen gradient layer may throughout the
`layer depth be substantially linear or non—linear. Alterna—
`tively (or additionally), the layer may include decreasing
`oxygen concentrations that are both linear and non—linear at
`selected regions thereof throughout the layer depth.
`[0019] The oxygen gradient layer may be obtained by
`introducing a portion of oxygen gas at the leading section of
`
`the coater zone where the deposition of silicon nitride
`occurs. While not wishing to be bound by any particular
`theory, it is believed that the oxygen gradient layer is in part
`responsible for improved mechanical durability in sputter
`coated glass products which are subsequently heat treated.
`
`[0020] The oxygen gradient that may be present in the
`coatings of the present invention is most typically embodied
`in a decrease in the oxygen concentration, expressed in
`atomic percent (at. ’70), which is present in the layer per unit
`depth of the layer, expressed in Angstroms (A), of about 0.6
`at. %/A or less. Oxygen gradients of between about 0.1 to
`about 0.6 at. %/A are thus embodied in the present inven-
`tion. According to some especially preferred embodiments,
`an oxygen gradient of between about 0.15 to about 0.25 at.
`%/A is obtained.
`
`[0021] As one specific example, a plot of atomic percent
`vs. depth was generated for Test Sample 3 of Example III
`below and is presented as accompanying FIG. 3. As shown
`therein, the oxygen concentration decreases from between
`about 35 to about 40 at. % at a depth of about 375 A in the
`coating, to a relatively constant value of about 5 at. % at a
`layer depth of about 200 A.
`[0022] Those skilled in this art will recognize that a wide
`variety of oxygen gradient layers may be produced depend-
`ing on the particular process techniques employed. For
`example, variations in the line speed of the glass substrate
`through the sputter coater and/or variations in the quantity of
`oxygen introduced at the leading edge of the coater zone
`may be employed so as to produce a silicon oxynitride layer
`having the desired oxygen gradient.
`
`[0023] A greater understanding of this invention will be
`achieved by careful consideration of the following non—
`limiting Examples.
`
`EXAMPLES
`
`[0024] Example I
`
`[0025] A low emissivity coating comprised of layers (11)
`through (e) as identified generally in FIG. 1 was applied
`onto a float glass substrate using a multi-chamber sputter-
`coater (Airco, Inc.) at a line speed of 175 in/min under the
`following conditions:
`
`Layer (u):
`
`Layer (a):
`
`Layer (b):
`
`TiOZ - 6 Dual C-MAG cathodes (12 Ti metal targets)
`Three cathodes are in the first coat /.one ((771) and three
`are in the second Coat Zone (CZ2).
`Each coat zone is run identically , DC Reactive sputtering
`Pressure = 3.5 rnTorr
`Gas Ratio (60% 02/40% Ar)
`Total gas flow = 1850 (seem)
`Power , ~80 kW per target
`SixNy - 3 Dual C-MAG cathodes (6 Plasma Sprayed Si/Al
`targets ~8% Al)
`Bi-Polar Pulsed DC power
`Pressure = 2.5 rnTorr
`Gas Ratio (30% N2, 70% Ar)
`Total gas [low = 1425 sccm
`Power - ~5 kW per target
`NiCrN , 1 Planar cathode (80% Ni,’20% Cr)
`DC Sputtered
`Pressure = 2.5 mTorr
`Gas Ratio (85% Ar, 15% N2)
`Total gas flow = 1125 seem
`Power - ~4.0 kW per target (Range 3 to 5 kW)
`
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`US 2001/0041252 A1
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`Nov. 15, 2001
`
`What is claimed is:
`1. A surface-coated glass article comprised of a glass
`substrate and a multiple layer coating on a surface of the
`glass substrate, wherein said coating includes a layer of a
`transparent dielectric material adjacent the surface of the
`glass substrate, respective layers nichrome and silver each
`sputter—coated onto the glass substrate in a nitrogen—contain—
`ing atmosphere.
`2. The surface-coated glass article of claim 1, wherein the
`coating further includes a layer of silicon oxynitridc inter-
`posed between said layer of dielectric material and said layer
`of nichrome.
`3. The surface-coated glass article of claim 2, wherein
`said silicon oxynitride layer includes an oxygen gradient
`layer.
`4. The surface-coated glass article of claim 3, wherein
`said oxygen gradient layer has an oxygen concentration
`which decreases between about 0.1 to about 0.6 at. %/A
`from one location in the layer to another location at a
`dilIerent depth in the layer.
`5. The surface—coated glass article of claim 4, wherein
`said oxygen gradient layer has an oxygen concentration
`which decreases between about 0.15 to about 0.25 at. %/A.
`6. The surface-coated glass article of claim 3, 4 or 5,
`wherein said oxygen gradient layer has an oxygen concen-
`tration which is greater at a location nearer to the glass
`substrate.
`7. The surface-coated glass article of claim 1, wherein the
`dielectric material is at least one selected from the group
`consisting of TiOZ, BiO3, PbO and mixtures thereof.
`8. The surface-coated glass article as in claim 1, wherein
`the coating further includes, from the layer of silver out—
`wardly, a second layer of nitrided nichrome, and an outer
`layer of Si3N4.
`9. The surface-coated glass article as in claim 1, wherein
`the coating further includes a layer of Si3N4 interposed
`between said dielectric material and said layer of nichrome.
`10. A surface-coated glass article comprised of a glass
`substrate and a multiple layer coating comprising the fol—
`lowing layers formed on a surface of the glass substrate,
`from the surface outwardly:
`
`(1) a layer of transparent dielectric material;
`(2) an inner layer of Si3N4 or a layer of silicon oxynitride;
`(3) a first layer of nitrided nichrome;
`
`(4) a layer of silver which is sputter—coated onto the glass
`substrate in a nitrogen-containing atmosphere;
`
`(5) a second layer of nitrided nichrome; and
`
`(6) an outer layer of Si3N4.
`11. The surface-coated glass article of claim 10, wherein
`the dielectric material is at least one selected from the group
`consisting of TiOz, Bi03, PbO and mixtures thereof.
`12. The surface—coated glass article of claim 1 or 10,
`having a light transmission of at least about 72%.
`13. The surface—coated glass article of claim 12, having
`transmitted a*, b* Values of between about —2.0 to —4.0, and
`between about —0.5 to about 1.5, respectively.
`14. The surface-coated glass article of claim 1 or 10,
`wherein the layers have the following thicknesses in Ang-
`stroms:
`
`(1) between about 100-200;
`
`(2) between about 25-200;
`
`Layer (e):
`
`Layer (d)
`
`Layer (e):
`
`—continued
`
`Ag - 1 Planar Cathode (100% Silver)
`3C Sputtered
`’ressure = 2.5 m"orr
`Gas Ratio (85% Ar, 15% N2)
`Total gas flow = 125 sccm
`3ower 7 ~7.75 kW per target (Range 5 to 9 kW,
`{s = 3 to 10 Ohm per square)
`NiCrN - l Planar cathode (80% Ni/20% Cr)
`)C Sputtered
`’ressure = 2.5 mTorr
`Gas Ratio (85% Ar, 15% N2)
`Total gas flow = 125 seem
`)ower - ~4.0 kW per target (Range 3 to 5 kW)
`SixNy 7 3 Dual CAMAG cathodes (6 Plasma Sprayed Si/Al
`targets ~8% Al)
`3i-Polar Pulsed DC power
`)ressure = 2.5 mTorr
`Gas Ratio (60% N2, 40% Ar)
`Total gas flow = -050 seem
`’ower - ~28 kW 3er target
`
`
`
`
`
`[0026] Example 11
`
`[0027] Example I was repeated except that layer (a) was
`sputter-coated using the following conditions to form a
`silicon oxynitridc:
`
`Layer (a):
`
`SiOxNy - 3 Dual C-MAG cathodes (6 Plasma Sprayed
`Si/AI targets ~8% Al)
`Bi-Polar Pulsed DC power
`Pressure = 2.5 mTorr
`Gas Ratio (30% N2, 10% 02, 60% Ar)
`Total gas [low = 1425 sccm
`Power - ~7 kW per target
`
`[0028] Example 111
`
`[0029] Test Samples obtained from Example I (identified
`as Sample Nos. 4 and 5) and Example II (identified as
`Sample Nos. 6 and 7) were tested for light transmissivity and
`transmitted a*, b* Values. In comparison, 'l‘est Sample Nos.
`1-2 and 8-9 having non-nitrided NiCr and Ag layers (all
`other layers in the stack being substantially the same as
`Sample Nos. 4-7) were also tested for light transmissivity
`and a*, b* Values. Comparative Test Sample No. 3 was
`identical to Test Sample Nos. 1-2, except that a layer of
`silicon oxynitride was interposed between the TiO2 and NiCr
`layers. The data appear in accompanying FIG. 2.
`
`[0030] As will be observed, the transmissivity of Samples
`4-7 was acceptably high (i.e., greater than about 72%) with
`low a* transmission Values. In this regard, it was noted that,
`even though the b* Value of Sample Nos. 4-7 increased as
`compared to Test Sample Nos. 1-3 and 8-9,
`the greater
`transmissivity of the former made the b* Value less critical.
`Thus, it was noted that when the transmission is high, the
`“blue” color hue is less sensitive.
`
`[0031] While the invention has been described in connec-
`tion with what
`is presently considered to be the most
`practical and preferred embodiment, it is to be understood
`that
`the invention is not
`to be limited to the disclosed
`embodiment, but on the contrary,
`is intended to cover
`various modifications and equivalent arrangements included
`within the spirit and scope of the appended claims.
`
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`US 2001/0041252 A1
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`NOV. 15, 2001
`
`(3) between about 2-40;
`
`(4) between about 100-200;
`
`(5) between about 2-40; and
`
`(6) between about 350-600.
`15. A method of making a surface-coated glass article
`comprising sputter-coating on a surface of a glass substrate
`a multiple layer coating comprised of a layer of a transparent
`dielectric material adjacent the surface of the glass substrate,
`and respective layers of nichrome and silver which are
`sputter-coated onto the glass substrate in a nitrogen-contain-
`ing atmosphere.
`16. The method of claim 15, wherein said layers of
`nichrome and silver are each formed by sputter-coating in a
`gaseous atmosphere comprised of nitrogen and argon,
`wherein the nitrogen is present in the atmosphere in an
`amount less than about 25%.
`17. The method of claim 16, wherein nitrogen is present
`in an amount between about 15% to about 25%.
`18. The method of claim 16, wherein the ratio of argon to
`nitrogen is about 85:15.
`19. The method of claim 16, which further comprises
`forming a silicon oxynitride layer between said layer of
`dielectric material and said layer of nichrome.
`20. The method of claim 15, wherein said layer of silicon
`oxynitride is formed by sputter—coating in a gaseous atmo—
`sphere comprised of nitrogen, oxygen and argon, wherein
`
`in the atmosphere in an amount
`the oxygen is present
`between about 5 to about 50%.
`21. The method of claim 20, wherein oxygen is present in
`the atmosphere in an amount of about 10%.
`22. The method of claim 21, wherein the atmosphere
`comprises about 30% nitrogen, about 10% oxygen and about
`60% argon.
`23. The method of any one of claims 15-22, wherein the
`sputter-coating of the silicon oxynitride layer includes using
`an aluminum-containing silicon target.
`24. The method of claim 23, wherein the target includes
`about 8% by weight aluminum.
`25. The method of claim 19 or 20, comprising forming the
`silicon oxynitride layer so as to include an oxygen gradient
`layer therein.
`26. The method of claim 25, wherein said oxygen gradient
`layer is formed so as to exhibit an oxygen concentration
`which decreases between about 0.1 to about 0.6 at. %/10A
`from one location in the layer to another location at a
`dilIerent depth in the layer.
`27. The method of claim 26, wherein said oxygen gradient
`layer has an oxygen concentration which decreases between
`about 0.15 to about 0.25 at. %/io\.
`28. The surface-coated glass article of claim 25, wherein
`said oxygen gradient layer has an oxygen concentration
`which is greater at a location nearer to the glass substrate.
`*
`*
`=1:
`*
`*
`
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