U.S. patent application number 12/876625 was filed with the patent office on 2011-03-10 for dielectric-layer-coated substrate and installation for production thereof.
This patent application is currently assigned to SAINT-GOBAIN GLASS FRANCE. Invention is credited to Carole BAUBET, Klaus Fischer, Jean-Christophe Giron, Alfred Hofrichter, Manfred Jansen, Marcus Loergen, Eric Mattman, Nicolas Nadaud, Jean-Paul Rousseau.
Application Number | 20110056825 12/876625 |
Document ID | / |
Family ID | 33515495 |
Filed Date | 2011-03-10 |
United States Patent
Application |
20110056825 |
Kind Code |
A1 |
BAUBET; Carole ; et
al. |
March 10, 2011 |
DIELECTRIC-LAYER-COATED SUBSTRATE AND INSTALLATION FOR PRODUCTION
THEREOF
Abstract
The invention relates to a substrate (1), especially a glass
substrate, coated with at least one dielectric thin-film layer
deposited by sputtering, especially magnetically enhanced
sputtering and preferably reactive sputtering in the presence of
oxygen and/or nitrogen, with exposure to at least one ion beam (3)
coming from an ion source (4), characterized in that said
dielectric layer exposed to the ion beam is crystallized.
Inventors: |
BAUBET; Carole; (Aachen,
DE) ; Fischer; Klaus; (Alsdorf, DE) ; Loergen;
Marcus; (Herzogenrath, DE) ; Giron;
Jean-Christophe; (Aachen, DE) ; Nadaud; Nicolas;
(Gentilly, FR) ; Mattman; Eric; (Paris, FR)
; Rousseau; Jean-Paul; (Boulogne, FR) ;
Hofrichter; Alfred; (Aachen, DE) ; Jansen;
Manfred; (Geilenkirchen, DE) |
Assignee: |
SAINT-GOBAIN GLASS FRANCE
Courbevoie
FR
|
Family ID: |
33515495 |
Appl. No.: |
12/876625 |
Filed: |
September 7, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10562121 |
Jun 28, 2006 |
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PCT/FR04/01651 |
Jun 28, 2004 |
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12876625 |
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Current U.S.
Class: |
204/192.11 |
Current CPC
Class: |
H01J 2211/446 20130101;
C23C 14/086 20130101; C03C 17/36 20130101; C23C 14/0052 20130101;
C03C 17/2456 20130101; C03C 2217/78 20130101; B32B 17/10174
20130101; C03C 17/3618 20130101; C03C 17/3652 20130101; C03C
17/3644 20130101; C03C 17/366 20130101; C23C 14/5833 20130101; C03C
17/225 20130101; C03C 17/3626 20130101; C23C 14/08 20130101; C03C
17/3613 20130101; C03C 17/22 20130101; C03C 2218/155 20130101; C03C
17/245 20130101; C03C 2218/154 20130101; C03C 2217/21 20130101;
C23C 14/3442 20130101; C03C 2217/281 20130101 |
Class at
Publication: |
204/192.11 |
International
Class: |
C23C 14/34 20060101
C23C014/34 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 2003 |
FR |
03/07847 |
Claims
1. A process for depositing dielectric thin-film layer(s) on a
substrate comprising depositing at least one dielectric thin-film
layer on a substrate by sputtering in a sputtering chamber, wherein
at least one ion beam coming from an ion source is present in the
sputtering chamber and the at least one ion beam crystallizes the
dielectric thin-film layer(s).
2. The process as claimed in claim 1, wherein the ion beam is an
oxygen ion beam.
3. The process as claimed in claim 1, wherein the ion beam is
created with an energy of between 200 and 2000 eV.
4. The process as claimed in claim 1, wherein the dielectric
thin-film layer(s) has a very low roughness.
5. The process as claimed in claim 1, wherein the ion beam is
present in the sputtering chamber simultaneously with the
deposition of the dielectric thin-film layer(s).
6. The process as claimed in claim 1, wherein the ion beam is
present in the sputtering chamber after the dielectric thin-film
layer(s) has been deposited.
7. The process as claimed in claim 1, wherein the ion beam is
directed onto the substrate along a direction making a nonzero
angle with the surface of the substrate.
8. The process as claimed in claim 1, wherein the ion beam is
directed onto at least one cathode along a direction making a
nonzero angle with the surface of the cathode.
9. The process as claimed in claim 1, wherein the ion beam is
created from a linear source.
10. The process as claimed in claim 1, wherein at least one
functional layer is deposited on said dielectric thin-film layer
and said functional layer undergoes crystallization.
11. The process as claimed in claim 10, wherein the at least one
functional layer is based on silver and the size of the
crystallites of the functional layer is increased by 30 to 40%.
12. The process as claimed in claim 1, wherein the dielectric
thin-film layer is based on zinc oxide.
13. The process as claimed in claim 1, wherein the ion beam is
created in the sputtering chamber from a linear ion source
simultaneously with the deposition of the dielectric thin-film
layer.
14. The process as claimed in claim 13, further comprising the
dielectric thin-film layer undergoing an additional treatment with
at least one additional ion beam.
15. The process as claimed in claim 1, wherein the sputtering is
magnetically enhanced sputtering or reactive sputtering.
16. The process as claimed in claim 1, wherein the sputtering
occurs in the presence of oxygen and/or nitrogen.
17. The process as claimed in claim 7, wherein the ion beam is
directed onto the substrate along a direction making an angle of 10
to 80.degree. with the surface of the substrate.
18. The process as claimed in claim 8, wherein the ion beam is
directed onto the cathode along a direction making an angle of 10
to 80.degree. with the surface of this cathode.
19. The process as claimed in claim 10, wherein the at least one
functional layer is based on silver.
Description
[0001] The present invention relates to the field of
dielectric-based thin-film coatings, especially of the metal oxide,
nitride or oxynitride type, which are deposited on transparent
substrates, especially glass substrates, using a vacuum deposition
technique.
[0002] The invention relates to a coated substrate, to a
manufacturing process, to an installation for manufacturing and for
applying the substrate and/or the process for producing glazing
assemblies, especially double-glazing or laminated glazing
assemblies, comprising at least one substrate according to the
invention.
[0003] For the purpose of manufacturing what are called
"functional" glazing assemblies, the usual practice is to deposit,
on at least one of the substrates of which they are composed, a
thin-film layer or a thin-film multilayer, so as to give the
glazing assemblies optical (for example antireflection) properties,
properties in the infrared (low emissivity) and/or electrical
conduction properties. Layers based on an oxide and/or nitride
dielectric are frequently used, for example on either side of a
silver layer or a doped metal oxide layer, or as an interferential
layer in multilayers in which low- and high-refractive index
dielectrics alternate.
[0004] Layers deposited by sputtering are reputed to be somewhat
less chemically and mechanically resistant than layers deposited by
pyrolithic deposition. Thus, the experimental technique of
ion-beam-assisted deposition has been developed in which a layer is
bombarded with an ion beam, for example an oxygen or argon ion
beam, which makes it possible to increase the density of the layer
and its adhesion to the carrier substrate. This technique has for a
long time been applicable only to very small sized substrates,
owing to the problems posed in particular in terms of convergence
between, on the one hand, the ion beam coming from a very localized
source and, on the other hand, the particles resulting from the
evaporation or sputtering of the target.
[0005] Document EP 601 928 discloses a sequential treatment of the
deposited layer, by firstly depositing a layer in a sputtering
chamber and then bombarding this dielectric layer after it has been
deposited with a "low energy" ion beam coming from a point source,
with an energy allowing the sputtering of the layer under the
impact of the ions of the beam to be limited, typically of less
than 500 eV and around one hundred eV.
[0006] This treatment is aimed essentially at increasing the
physical and/or chemical durability of the layer, by densification
of the layer, and makes it possible to achieve a lower surface
roughness of the layer, favoring the subsequent "layering" of a
layer subsequently deposited on top of it.
[0007] However, this treatment has the drawback of only being able
to be carried out on a fully deposited layer.
[0008] Another drawback of this treatment is that it allows only
densification of the layer thus treated and this densification
causes an increase in the refractive index of the layer thus
treated. The layers thus treated therefore cannot replace the
untreated layers, because of their different optical properties,
and mean that the multilayer systems, in which the material must be
included, have to be completely redefined.
[0009] In addition, this treatment is not optimized for being
carried out on a large substrate, for example for the production of
an architectural glazing assembly.
[0010] Furthermore, this process is not at all compatible with the
sputtering process, especially magnetically enhanced sputtering and
preferably reactive sputtering in the presence of oxygen and/or
nitrogen, especially because of the very different working
pressures: at the time of this invention, the ion sources operated
at pressures 10 to 100 times lower than the pressures used in the
processes for sputtering, especially magnetically enhanced
sputtering and preferably reactive sputtering in the presence of
oxygen and/or nitrogen.
[0011] More recently, ion sources have been developed that are more
compatible with processes for depositing thin films by sputtering,
in particular by solving the problem of convergence of the particle
beams and by improving the matching between the size and the
geometry, on the one hand, of the cathode and, on the other hand,
of the ion source. These systems, known as "linear sources", are
described for example in documents U.S. Pat. No. 6,214,183 or U.S.
Pat. No. 6,454,910.
[0012] Document WO 02/46491 describes the use of a source of this
type for producing a functional silver oxide layer by sputtering
using a silver target with bombardment by an oxygen ion beam. The
ion beam is used to densify the silver material and convert it into
a layer containing silver oxide. As a result of the densification,
the silver oxide layer is capable of absorbing and/or reflecting a
significant amount of the UV.
[0013] The object of the present invention is to remedy the
drawbacks of the prior art and to provide novel thin-film materials
that can be used to coat transparent substrates of the glass type,
novel deposition processes and novel installations.
[0014] The invention relies on the fact that it is possible to
deposit thin-film layers made of a dielectric, especially an oxide
and/or nitride, with exposure to an ion beam by controlling the
conditions so that the material of the final layer has a better
degree of crystallization, much greater than the degree of
crystallization of the material deposited conventionally, that is
to say without subjecting the layer to at least one ion beam.
[0015] In this regard, the subject of the invention is a substrate,
especially a glass substrate, as claimed in claim 1. The substrate
according to the invention is coated with at least one dielectric
thin-film layer deposited by sputtering, especially magnetically
enhanced sputtering and preferably reactive sputtering in the
presence of oxygen and/or nitrogen, with exposure to at least one
ion beam coming from an ion source, and the deposited dielectric
layer exposed to the ion beam is crystallized.
[0016] The term "crystallized" is understood to mean that at least
30% of the constituent material of the dielectric layer exposed to
the ion beam is crystallized and that the size of the crystallites
can be detected by X-ray diffraction, i.e. they have a diameter of
greater than a few nanometers.
[0017] The ion beam used to implement the present invention is what
is called a "high-energy" beam, typically having an energy ranging
from around several hundred eV to several thousand eV.
[0018] Advantageously, the parameters are controlled in such a way
that the dielectric layer deposited on the substrate by sputtering
with exposure to the ion beam has a very low roughness.
[0019] The term "very low roughness" is understood to mean that the
dielectric layer exposed to the ion beam has a roughness at least
20%, and preferably at least 50%, less than that of the same
dielectric layer not exposed to the ion beam.
[0020] The dielectric layer exposed to the ion beam may thus have a
roughness of less than 0.1 nm for a thickness of 10 nm.
[0021] Advantageously, the parameters may also be controlled in
such a way that the layer has an index very much less or very much
greater than the index of a layer deposited without an ion beam,
but which may also be close to the index of a layer deposited
without an ion beam.
[0022] Within the meaning of the present description, the term
"close" implies an index that differs from the reference value by
at most around 5%.
[0023] The invention also makes it possible to create an index
gradient in the deposited layer.
[0024] In a variant, said layer thus has an index gradient adjusted
according to the parameters of the ion source.
[0025] Advantageously, for at least some of the dielectric
materials that can be deposited, whatever the index modification
produced, the density of the dielectric layer deposited on the
substrate by sputtering with exposure to the ion beam may be
maintained with a similar or identical value.
[0026] Within the meaning of the present description, a "similar"
density value differs from the reference value by at most around
10%.
[0027] The invention applies in particular to the production of a
dielectric layer made of a metal oxide or silicon oxide, whether
stoichiometric or nonstoichiometric, or made of a metal nitride or
oxynitride or silicon nitride or oxynitride.
[0028] In particular, the dielectric layer may be made of an oxide
of at least one element taken from silicon, zinc, tantalum,
titanium, tin, aluminum, zirconium, niobium, indium, cerium, and
tungsten. Among mixed oxides that can be envisioned, mention may in
particular be made of indium tin oxide (ITO).
[0029] The layer may be obtained from a cathode made of a doped
metal, that is to say one containing a minor element: as an
illustration, it is common practice to use cathodes made of zinc
containing a minor proportion of another metal, such as aluminum or
gallium. In the present description, the term "zinc oxide" is
understood to mean a zinc oxide possibly containing a minor
proportion of another metal. The same applies to the other oxides
mentioned.
[0030] For example, a zinc oxide layer deposited according to the
invention may have a degree of crystallinity of greater than 90%
and especially greater than 95% and an RMS roughness of less than
1.5 nm and especially around 1 nm.
[0031] This zinc oxide layer deposited according to the invention
may have a refractive index that can be adjusted to a value of less
than or equal to 1.95, especially around 1.35 to 1.95. Its density
may be maintained at a value close to 5.3 g/cm.sup.3 and especially
at a value of around 5.3.+-.0.2 g/cm.sup.3, identical to the
density of a ZnO layer deposited at low pressure, which is around
5.3 g/cm.sup.3.
[0032] Zinc oxide layers having a refractive index adjusted to a
value of less than 1.88 and similar to this value may be obtained
by setting the sputtering conditions (especially the oxygen content
of the atmosphere) so as to deviate slightly from the stoichiometry
of the intended oxide so as to compensate for the impact of the ion
bombardment.
[0033] The dielectric layer may also be made of silicon nitride or
oxynitride. Such nitride dielectric layers may be obtained by
setting the sputtering conditions (especially the nitrogen content
of the atmosphere) so as to deviate slightly from the stoichiometry
of the intended nitride, so as to compensate for the impact of the
ion bombardment.
[0034] In general, the ion beam has the effect of improving the
mechanical properties of the dielectric layer.
[0035] As a result of the ion bombardment, quantities of one or
more bombarded species are introduced into the layer, in a
proportion that depends on the nature of the gas mixture at the
source and on the source/cathode/substrate configuration. As an
illustration, a layer deposited under bombardment by an argon ion
beam may include argon with a content of around 0.2 to 0.6 at %,
especially about 0.45 at %.
[0036] Generating the ion beam via an ion source that uses soft
iron cathodes or cathodes of any other material, especially
paramagnetic material, which are eroded during the process, may be
responsible for the presence of traces of iron in the deposited
layer. It has been confirmed that iron present with a content of
less than 3 at % or less is acceptable as it does not degrade the
properties, especially optical or electrical properties, of the
layer. Advantageously, the deposition parameters (especially the
substrate transport speed) are adjusted so as to have an iron
content of less than 1 at %.
[0037] By preserving the usual optical properties, it is very easy
to incorporate the dielectric layers thus obtained into multilayers
known for manufacturing what are called "functional" glazing
assemblies, in particular using a silver-based metal functional
layer.
[0038] Specific multilayers may be designed that incorporate a
dielectric of index adjusted to a different value from the standard
value.
[0039] Thus, the subject of the invention is a substrate coated
with a multilayer in which a silver layer is deposited on top of
said dielectric layer exposed to the ion beam. Another dielectric
layer may then be deposited on top of this silver layer.
[0040] This configuration proves to be particularly advantageous
when the lower dielectric layer is based on zinc oxide and/or tin
oxide as they give rise to particularly well oriented growth of the
silver layer on the oxide layer, with improved final properties. It
is known that the presence of a zinc oxide layer beneath the silver
has an appreciable influence on the quality of said silver layer.
The formation of the silver layer on the zinc oxide layer deposited
according to the invention results in a quite remarkable
improvement.
[0041] In fact it is observed that the silver layer thus formed is
better crystallized with an increase of 15 to 40% in the
crystalline phase (diffraction from (111) planes) compared with the
amorphous phase.
[0042] In this regard, the subject of the invention is also a
process according to the invention for improving the
crystallization of a silver layer deposited on a dielectric layer,
especially on a dielectric layer based on zinc oxide, in which said
dielectric layer is deposited on the substrate by sputtering,
especially magnetically enhanced sputtering and preferably reactive
sputtering in the presence of oxygen and/or nitrogen, with exposure
to at least one ion beam, preferably coming from a linear source.
According to this process, at least one functional layer,
especially one based on silver, is deposited on said dielectric
layer and said functional layer undergoes a crystallization step.
The size of the crystallites of the silver layer can therefore be
increased by around 15 to 40%, especially 30 to 40% (diffraction
from (111) planes).
[0043] This is manifested by a reduction in the resistivity of the
silver (which is directly related to the energy emissivity
properties) or a reduction in the surface resistance
R.sub..quadrature. by at least 10%, for the same silver thickness,
with an R.sub..quadrature. value of less than
6.OMEGA./.quadrature., or even less than 2.1.OMEGA./.quadrature.,
especially around 1.9 .OMEGA./.quadrature..
[0044] These substrates are thus particularly advantageous for
producing low-emissivity or solar-controlled glazing assemblies, or
else translucent elements with a high electrical conductivity, such
as the screens for electromagnetic shielding of plasma display
devices.
[0045] In these substrates, another dielectric layer may be placed
on top of the silver layer. It may be chosen based on the
abovementioned oxides or nitrides or oxynitrides. The other layer
itself may or may not be deposited with exposure to an ion
beam.
[0046] The multilayer may include at least two silver layers or
even three or four silver layers.
[0047] Examples of multilayers that can be produced according to
the invention comprise the following sequences of layers: [0048]
ZnO/Ag.sup.(i)/oxide such as ZnO [0049]
Si.sub.3N.sub.4/ZnO.sup.(i)/Ag/oxide such as ZnO [0050]
Si.sub.3N.sub.4/ZnO.sup.(i)/Ag/Si.sub.3N.sub.4/(optionally an
oxide) [0051]
Si.sub.3N.sub.4/ZnO.sup.(i)/Ag/Si.sub.3N.sub.4/ZnO.sup.(i)/Ag/Si.s-
ub.3N.sub.4 [0052]
Si.sub.3N.sub.4/ZnO.sup.(i)/Ag/Si.sub.3N.sub.4/ZnO.sup.(i)/Ag/Si.sub.3N.s-
ub.4/(oxide) where .sup.(i) indicates that the layer is exposed to
the ion beam and where a blocking metal layer may be inserted above
and/or below at least one silver layer.
[0053] The substrate used could also be made of a plastic,
especially a transparent plastic.
[0054] The subject of the invention is also a process for
manufacturing a substrate as described above, i.e. a process for
depositing a multilayer, in which at least one dielectric layer is
deposited on the substrate by sputtering, especially magnetically
enhanced sputtering and preferably reactive sputtering in the
presence of oxygen and/or nitrogen, in a sputtering chamber, with
exposure to at least one ion beam coming from an ion source. In the
process according to the invention, the ion beam is created from a
linear source and the refractive index of said dielectric layer
exposed to the ion beam may be adjusted according to the parameters
of the ion source.
[0055] The refractive index of the dielectric layer exposed to the
ion beam may be decreased or increased relative to the index of
this layer deposited without an ion beam.
[0056] Advantageously, for at least some of the dielectric
materials to be deposited, whatever the index modification
produced, the density of the dielectric layer deposited on the
substrate by sputtering with exposure to the ion beam is
maintained.
[0057] Exposure to the ion beam takes place in the sputtering
chamber simultaneously with and/or sequentially after the
deposition of the layer by sputtering.
[0058] The expression "simultaneously with" is understood to mean
that the constituent material of the dielectric thin-film layer is
subjected to the effects of the ion beam while it is yet to be
completely deposited, that is to say that it has not yet reached
its final thickness.
[0059] The term "sequentially after" is understood to mean that the
constituent material of the dielectric thin-film layer is subjected
to the effects of the ion beam when the layer has been completely
deposited, that is to say after it has reached its final
thickness.
[0060] In the variant with exposure simultaneously with deposition,
the position of the ion source(s) is preferably optimized so that
the maximum density of sputtered particles coming from the target
is juxtaposed with the ion beam(s).
[0061] Preferably, to produce an oxide-based dielectric layer, an
oxygen ion beam is created with an atmosphere containing very
largely oxygen, especially 100% oxygen, at the ion source, whereas
the atmosphere at the sputtering cathode is preferably composed of
100% argon.
[0062] In this variant, exposure to the ion beam takes place
simultaneously with the deposition of the layer by sputtering. For
this purpose, it is unnecessary to limit the ion energy as in the
prior art; on the contrary, an ion beam with an energy between 200
and 2000 eV or even between 500 and 5000 eV, especially between 500
and 3000 eV, is advantageously created.
[0063] The ion beam may be directed onto the substrate and/or onto
the sputtering cathode, especially along a direction or at a
non-zero angle with the surface of the substrate and/or of the
cathode respectively, such that the ion beam juxtaposes with the
flux of neutral species ejected from the target by sputtering.
[0064] This angle may be around 10 to 80.degree. relative to the
normal to the substrate, measured for example vertically in line
with the center of the cathode, and vertically in line with the
axis of the cathode when it is cylindrical.
[0065] In the case of direct flux on the target, the ion beam
coming from the source juxtaposes with the "racetrack" of the
target created by the sputtering, that is to say the centers of the
two beams, coming from the cathode and from the ion source
respectively, meet at the surface of the substrate.
[0066] Advantageously, the ion beam may also be used outside the
racetrack and directed toward the cathode, in order to increase the
degree of use of the target (ablation). The ion beam can therefore
be directed onto the sputtering cathode at an angle of .+-.10 to
80.degree. relative to the normal to the substrate passing through
the center of the cathode, and especially through the axis of the
cathode when it is cylindrical.
[0067] The source/substrate distance, in a sequential or
simultaneous configuration, is from 5 to 25 cm, preferably 10.+-.5
cm.
[0068] The ion source may be positioned before or after the
sputtering cathode along the direction in which the substrate runs
(i.e. the angle between the ion source and the cathode or the
substrate is respectively negative or positive relative to the
normal to the substrate passing through the center of the
cathode).
[0069] In a variant of the invention, an ion beam is created in the
sputtering chamber using a linear ion source simultaneously with
the deposition of the layer by sputtering, and then the deposited
layer undergoes an additional treatment with at least one other ion
beam.
[0070] The present invention will be more clearly understood on
reading the detailed description below of illustrative but
non-limiting examples and from FIG. 1 appended hereto, which
illustrates a longitudinal sectional view of an installation
according to the invention.
[0071] To manufacture "functional" glazing assemblies
(solar-controlled glazing, low-emissivity glazing, heated windows,
etc.), it is usual practice to deposit a thin-film multilayer
comprising at least one functional layer on a substrate.
[0072] When this functional layer (or these functional layers) is
(or are) especially based on silver, it is necessary to deposit a
silver layer (thickness between 8 and 15 nm) whose normal
emissivity and/or electronic resistivity are minimal.
[0073] To do this, it is known that the silver layer must be
deposited on an oxide sublayer which is:
[0074] (i) made of perfectly crystallized zinc (wurtzite phase)
with a preferred orientation formed by the basal planes ((0002)
planes) parallel to the substrate; and
[0075] (ii) perfectly smooth (minimal roughness).
[0076] The current technical solutions for depositing the zinc
oxide do not allow both these characteristics to be obtained.
[0077] For example: [0078] the solutions for crystallizing zinc
oxide (by heating the substrate, increasing the cathode power,
increasing the thickness and increasing the oxygen content) result
in an increase in the roughness of the layer, which leads to an
appreciable degradation in the performance of the silver layer
deposited on top; and [0079] the solutions for depositing a zinc
oxide which is smooth or has a low roughness (low-pressure
deposition, deposition on a very small thickness) result in partial
amorphization of the silver layer, which impairs the quality of the
heteroepitaxial growth of the silver on the ZnO.
[0080] Within the context of the invention, it has been observed,
surprisingly, that the deposition in particular of zinc oxide, but
also of many other dielectrics, assisted by an ion beam coming from
a linear source makes it possible, under certain conditions, to
deposit a highly crystallized layer with an extremely low
roughness. This considerably improves the quality of the
epitaxially grown silver layer on the subjacent dielectric and
therefore both the optical and mechanical properties of the
multilayers.
CONTROL EXAMPLE 1
[0081] In this example, a zinc oxide layer 40 nm in thickness was
applied to a glass substrate using an installation (10) illustrated
in FIG. 1.
[0082] The deposition installation comprised a vacuum sputtering
chamber (2) through which the substrate (1) ran along conveying
means (not illustrated here), along the direction and in the sense
illustrated by the arrow F.
[0083] The installation (2) included a magnetically enhanced
sputtering system (5). This system comprised at least one
cylindrical rotating cathode (but it could also have been a flat
cathode), extending approximately over the entire width of the
substrate, the axis of the cathode being placed approximately
parallel to the substrate. This sputtering system (5) was placed at
a height H5 of 265 mm above the substrate.
[0084] The material extracted from the cathode of the sputtering
system was directed onto the substrate approximately as a beam
(6).
[0085] The installation (2) also included a linear ion source (4)
emitting an ion beam (3), which also extended approximately over
the entire width of the substrate. This linear ion source (4) was
positioned at a distance L4 of 170 mm from the cathode axis, in
front of the cathode with regard to the direction in which the
substrate runs, at a height H4 of 120 mm above the substrate.
[0086] The ion beam (3) was directed at an angle A relative to the
vertical to the substrate passing through the axis of the
cathode.
[0087] This deposition was carried out using a known sputtering
technique on the substrate (1) running through a sputtering chamber
(2) past a rotating cathode, based on Zn containing about 2% by
weight of aluminum in an atmosphere containing argon and oxygen.
The run speed was at least 1 m/min.
[0088] The deposition conditions given in Table 1 a below were
adapted so as to create a slightly substoichiometric zinc oxide
layer with an index of 1.88 (whereas a stoichiometric ZnO layer has
an index of 1.93-1.95).
[0089] This layer was analyzed by X-ray reflectometry in order to
determine its density and thickness, and by X-ray diffraction in
order to determine its crystallinity. The spectrum revealed a peak
at 2.theta.=34.degree. typical of (0002) ZnO. The size of the
crystallites was deduced from the diffraction spectrum using the
conventional Scherrer formula and using the fundamental
parameters.
[0090] The light transmission through the substrate, the light
reflection from the substrate and the resistance per square were
also measured. The measured values are given in Table 1b below.
EXAMPLE 1
[0091] In this example, a zinc oxide layer 40 nm in thickness was
applied according to the invention to a glass substrate.
[0092] This deposition was carried out by sputtering onto the
substrate, which ran through the same sputtering chamber as in
Control Example 1, in an atmosphere at the sputtering cathode
containing only argon. A linear ion source placed in the sputtering
chamber was used to create, simultaneously with the sputtering, an
ion beam using an atmosphere at the source composed of 100% oxygen.
The source was inclined so as to direct the beam onto the substrate
at an angle of 30.degree..
[0093] The modified deposition conditions made it possible to
produce a zinc oxide layer having an index of 1.88, the density of
which was identical to that of the control material.
[0094] The optical properties were barely affected by exposure to
the ion beam.
[0095] The X-ray diffraction spectrum revealed a very intense ZnO
(0002) peak showing, for constant ZnO thickness, an increase in the
amount of ZnO that crystallized and/or a more pronounced
orientation.
[0096] An iron constant of less than 1 at % was measured by
SIMS.
[0097] Rutherford backscattering spectroscopy measurements showed
that the ZnO layer contained 0.45 at % argon.
TABLE-US-00001 TABLE 1a Sputtering Ion Source Pressure Power Ar
O.sub.2 Energy Ar O.sub.2 Units .mu.bar kW sccm sccm eV sccm sccm
Cont. 0.8 3.0 80 70 -- -- -- Ex. 1 Ex. 1 0.9 3.0 100 0 2000 0
80
TABLE-US-00002 TABLE 1b Properties Density T.sub.L R.sub.L
R.sub..quadrature. ZnO Crystallite Size (nm) Units g/cm.sup.3 Index
% % .OMEGA./.quadrature. Scherrer Fund. Param. Cont. 5.30 1.88 83.8
16.1 .infin. 17 15 Ex. 1 Ex. 1 5.30 1.54 88.9 9.8 .infin. 12 12
EXAMPLE 2
[0098] In this example, a glass substrate was coated with the
following multilayer:
[0099] 10 nm ZnO/19.5 nm Ag/10 nm ZnO,
where the lower zinc oxide layer was obtained as in Example 1 with
exposure to an ion beam.
[0100] As in Example 1, the lower layer was produced by adapting
the residence time of the substrate in the chamber in order to
reduce the thickness of the oxide layer to 10 nm.
[0101] The substrate was then made to run past a silver cathode in
an atmosphere composed of 100% argon and then once again past a
zinc cathode in an argon/oxygen atmosphere under the conditions of
Control Example 1.
[0102] This multilayer was analyzed by X-ray diffraction in order
to determine its state of crystallization. The spectrum revealed a
peak at 2.theta.=34.degree. typical of ZnO, and a peak at
2.theta.=38.degree. typical of silver. The size of the silver
crystallites was determined from the diffraction spectrum using the
conventional Scherrer formula and using the fundamental
parameters.
[0103] The light transmission through the substrate, the light
reflection from the substrate and the surface resistance were also
measured.
[0104] The results are given in Table 2 below.
[0105] These properties are compared with those of a Control
Example 2 in which the lower zinc oxide layer was produced without
exposure to the ion beam.
[0106] The comparison reveals that the crystallization of the
silver layer is considerably improved when the subjacent zinc oxide
layer is produced with exposure to the ion beam, this being
manifested by a lower surface resistance, i.e. an improved
conductivity.
TABLE-US-00003 TABLE 2 Properties T.sub.L R.sub.L
R.sub..quadrature. Ag Crystallite Size (nm) Units % %
.OMEGA./.quadrature. Scherrer Fund. Param. Cont. 52.3 45.5 2.07
15.7 15.3 Ex. 2 Ex. 2 58.6 40.7 1.86 17.4 17.6
CONTROL EXAMPLE 3
[0107] In this example, the following multilayer was produced on a
glass substrate:
TABLE-US-00004 Substrate SnO.sub.2 TiO.sub.2 ZnO Ag NiCr SnO.sub.2
15 8 8 10 0.6 30
in which the lower zinc oxide layer was obtained as in Example 1
with exposure to an ion beam.
[0108] The zinc oxide layer was produced as in Example 1 by
adapting the residence time of the substrate in the chamber in
order to reduce the thickness of the oxide layer to 8 nm.
[0109] Next, the substrate was made to run past a silver cathode in
an atmosphere composed of 100% argon.
[0110] The optical and performance properties of Control Example 3
as single glazing (SG) and as double glazing (4/15/4 DG with the
internal cavity composed of 90% Ar) are given in Table 3 below.
EXAMPLE 3
[0111] The same deposition conditions as those of Control Example 3
were used, except that a linear ion source was placed in the
sputtering chamber and was used to create, simultaneously with the
sputtering, an ion beam during production of the zinc-oxide-based
layer, with an atmosphere at the source composed of 100% oxygen.
The source was inclined so as to direct the beam onto the substrate
at an angle of 30.degree. and was positioned at a distance of about
14 cm from the substrate.
[0112] These modified deposition conditions made it possible to
produce a zinc oxide layer having an index substantially identical
to that of the control layer.
[0113] The optical and performance properties of Example 3 as
single glazing (SG) and as double glazing (4/15/4 DG, the internal
cavity of which was composed of 90% Ar) are also given in Table 3
below.
TABLE-US-00005 TABLE 3 T.sub.L R.sub.L .epsilon..sub.n
R.sub..quadrature. (%) (%) a* b* (%) (.OMEGA./.quadrature.) Con. SG
86 4.4 3.7 -7.8 Ex. 3 Con. DG 77.4 11.6 0.7 -3.8 5.5 5 Ex. 3 Ex. 3
SG 86.5 4.2 3.2 -7.7 Ex. 3 DG 77.7 11.5 0.5 -3.8 5 4.5
[0114] As may be seen, the optical properties are barely affected
by exposure to the ion beam, but the thermal properties are
substantially improved, since a gain of 10% is obtained in terms of
resistance per square (R.sub..quadrature.) and in normal emissivity
(.di-elect cons..sub.n).
CONTROL EXAMPLE 4
[0115] A multilayer having the following layer thickness (in
nanometers) was produced on a glass substrate, corresponding to the
multilayer sold by Saint-Gobain Glass France under the brand name
PLANISTAR:
TABLE-US-00006 Substrate SnO.sub.2 ZnO Ag Ti ZnO Si.sub.3N.sub.4
ZnO Ag Ti ZnO Si.sub.3N.sub.4 25 15 9.0 1 15 56 15 13.5 1 15 21
[0116] The optical and performance properties of Control Example 4
as double glazing (4/15/4, with the internal cavity composed of 90%
Ar) are given in Table 4 below.
EXAMPLE 4
[0117] A multilayer having the same thicknesses as Control Example
4 was produced under the same conditions as those of Control
Example 4, except that a linear ion source was placed in the
sputtering chamber and used to create, simultaneously with the
sputtering, an ion beam during production of each zinc-oxide-based
layer directly subjacent to each silver-based functional layer.
[0118] The atmosphere at the source was composed of 100% oxygen.
The source was inclined so as to direct the beam onto the substrate
at an angle of 30.degree. and was positioned at a distance of about
14 cm from the substrate. The energy of the ion beam was, for each
pass, around 1000 eV. The pressure inside the chamber was 0.1
.mu.bar during the first pass and 4.3 .mu.bar during the second
pass, for a target power of 5.5 kW during the first pass and 10 kW
during the second pass.
[0119] These modified deposition conditions made it possible to
produce a zinc oxide layer having an index substantially identical
to that of the control layer.
[0120] The optical and performance properties of Example 4 as
double glazing (4/15/4 the internal cavity of which was composed of
90% Ar) are also given in Table 4 below.
[0121] As may be seen, the optical properties are barely affected
by exposure to the ion beam, but the thermal properties are greatly
improved, since again a gain of about 10% is obtained in terms of
resistance per square (R.sub..quadrature.).
TABLE-US-00007 TABLE 4 T.sub.L .lamda..sub.d p.sub.e R.sub.ext SF U
R.sub..quadrature. (%) (nm) (%) (%) L* a* b* (CEN) (W/m.sup.2 K)
(.OMEGA./.quadrature.) Con. 71.8 553 2.6 12.0 41.2 -2.3 -1.7 42
1.17 2.7 Ex. 4 Ex. 4 72.7 540 1.9 11.4 40.2 -2.7 -1.2 42 1.12
2.4
EXAMPLE 5
[0122] The following multilayer was deposited:
glass/Si.sub.3N.sub.4/ZnO (25 nm)/Ag (9 nm) and then the
crystallographic characteristics of the zinc oxide and the
electrical properties of the silver layer were measured. In
addition, the RMS roughness of a ZnO(25 nm) glass not coated with
silver and produced under the same conditions as previously was
evaluated. The angle of inclination A of the ion source relative to
the substrate was 30.degree.. The measured values are given in
Table 5 below.
TABLE-US-00008 TABLE 5 Area of the RMS roughness ZnO (0002) (nm)
Resistance per Bragg peak measured by AFM square of a 9 nm (a.u.)
(25 nm thickness) thick silver film ZnO without ion 0 1.8 8.2
assistance U = 1500 V 78 1.4 7.0 U = 3000 V 19 1.4 6.8
[0123] It may therefore be observed, surprisingly, that deposition
of ZnO assisted by an ion beam makes it possible in the above
multilayer to reduce the roughness of the layer thus deposited.
EXAMPLE 6
[0124] TiO.sub.2 monolayers were deposited on the glass with and
without assistance by an ion source and then the roughness was
measured by simulation of the optical properties (dispersion
relationship) and by X-ray reflectometry. The angle of inclination
A of the ion source relative to the substrate was 20.degree.. The
measured values are given in Table 6 below.
TABLE-US-00009 TABLE 6 Optical Roughness X-ray RMS Roughness (nm)
(nm) TiO.sub.2 without ion assistance 1.7 1.5 U = 1000 V 0 0.5 U =
2000 V 0 0.7
[0125] The present invention has been described in the foregoing by
way of example. Of course, a person skilled in the art would be
capable of producing various alternative embodiments of the
invention without thereby departing from the scope of the patent as
defined by the claims.
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