U.S. patent application number 09/843688 was filed with the patent office on 2001-10-04 for method for manufacturing electrode plate having transparent type or reflective type multi-layered conductive film.
Invention is credited to Fukuyoshi, Kenzo, Imayoshi, Koji, Kimura, Yukihiro.
Application Number | 20010026120 09/843688 |
Document ID | / |
Family ID | 11591733 |
Filed Date | 2001-10-04 |
United States Patent
Application |
20010026120 |
Kind Code |
A1 |
Fukuyoshi, Kenzo ; et
al. |
October 4, 2001 |
Method for manufacturing electrode plate having transparent type or
reflective type multi-layered conductive film
Abstract
An electrode plate for display device includes a substrate and a
multi-layered conductive film. The multi-layered conductive film
includes a lower side amorphous oxide layer, a silver-based layer,
and an upper side amorphous oxide layer. The lower side amorphous
oxide layer and the upper side amorphous oxide layer are formed of
an amorphous and amorphous-like material. The film thickness of the
upper side amorphous oxide layer is not larger than 20 nm.
Inventors: |
Fukuyoshi, Kenzo; (Tokyo,
JP) ; Kimura, Yukihiro; (Tokyo, JP) ;
Imayoshi, Koji; (Tokyo, JP) |
Correspondence
Address: |
STAAS & HALSEY LLP
700 11TH STREET, NW
SUITE 500
WASHINGTON
DC
20001
US
|
Family ID: |
11591733 |
Appl. No.: |
09/843688 |
Filed: |
April 30, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09843688 |
Apr 30, 2001 |
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09228644 |
Jan 12, 1999 |
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6249082 |
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Current U.S.
Class: |
313/479 ;
349/139; 427/126.1; 427/272; 427/419.1 |
Current CPC
Class: |
Y10T 428/2991 20150115;
G02F 2203/02 20130101; Y10T 428/2958 20150115; G02F 1/13439
20130101; G02F 2203/01 20130101 |
Class at
Publication: |
313/479 ;
349/139; 427/126.1; 427/419.1; 427/272 |
International
Class: |
B05D 001/36; B05D
005/12; H01J 031/00; G02F 001/1343; B05D 001/32 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 13, 1998 |
JP |
10-004720 |
Claims
1. An electrode plate for display device comprising: a substrate;
and a multi-layered conductive film, wherein said multi-layered
conductive film includes a silver-based layer, a lower side
amorphous oxide layer formed of an amorphous or amorphous-like
material for suppressing movements of silver atoms at an interface
with said silver-based layer, and an upper side amorphous oxide
layer formed of an amorphous or amorphous-like material for
suppressing movements of silver atoms at an interface with said
silver-based layer and at least a film thickness of said upper side
amorphous oxide layer is not larger than 20 nm.
2. The electrode plate for display device according to claim 1,
wherein said upper side amorphous oxide layer comprises an oxide
layer of which optical film thickness defined as a product of a
film thickness and a refractive index is not larger than 20 nm.
3. The electrode plate for display device according to claim 1,
which further comprises a protection layer formed on said upper
side amorphous oxide layer and in which a sum of the optical film
thicknesses of said upper side amorphous oxide layer and said
protection layer is not less than 70 nm.
4. The electrode plate for display device according to claim 1,
further comprising a protection layer formed on said upper side
amorphous oxide layer, said protection layer being an oxide layer
having a refractive index not larger than that of said upper side
amorphous oxide layer.
5. The electrode plate for display device according to claim 1,
wherein said lower side amorphous oxide layer has an underlaid
layer formed of an oxide layer having a refractive index not larger
than that of the lower side amorphous oxide layer.
6. The electrode plate for display device according to claim 1,
wherein said lower side amorphous oxide layer is formed of a mixed
oxide material which contains cerium oxide as a main material and
additionally contains at least one oxide material selected from a
group of ytrium oxide, zirconium oxide, niobium oxide, hafnium
oxide, tantalum oxide and tungsten oxide.
7. The electrode plate for display device according to claim 6,
wherein at least niobium oxide is selected to be added to the
cerium oxide which is the main material of said lower side oxide
layer.
8. The electrode plate for display device according to claim 6,
wherein said lower side amorphous oxide layer formed of an
amorphous or amorphous-like material is formed of a mixed oxide
which contains at least niobium oxide mixed with cerium oxide.
9. An electrode plate for display device comprising: a substrate;
and a multi-layered conductive film; wherein said multi-layered
conductive film includes a lower side amorphous oxide layer formed
of an amorphous or amorphous-like material for suppressing a
movement of silver atom at an interface with said silver-based
layer, a silver-based layer, and an upper side oxide layer and said
upper side oxide layer includes an oxide layer and an amorphous
oxide layer formed of an amorphous or amorphous-like material for
suppressing a movements of silver atoms at an interface with said
silver-based layer and a film thickness of said upper side
amorphous oxide layer is not larger than 20 nm.
10. The electrode plate for display device according to claim 9,
wherein an optical film thickness defined as a product of the film
thickness and a refractive index of said amorphous oxide layer
included in said upper side oxide layer is not larger than 20
nm.
11. The electrode plate for display device according to claim 9,
which further comprises a protection layer formed on said upper
side oxide layer and in which a sum of the optical film thicknesses
of said upper side oxide layer and said protection layer is not
less than 70 nm.
12. The electrode plate for display device according to claim 9,
further comprising a protection layer formed on said upper side
oxide layer, said protection layer being an oxide layer having a
refractive index not larger than that of said amorphous oxide layer
included in said upper side oxide layer.
13. The electrode plate for display device according to claim 9,
wherein said lower side amorphous oxide layer has an underlaid
layer formed of an oxide material having a refractive index not
larger than that of the lower side amorphous oxide layer.
14. The electrode plate for display device according to claim 9,
wherein said lower side amorphous oxide layer is formed of a mixed
oxide material which contains cerium oxide as a main material and
additionally contains at least one oxide material selected from a
group of ytrium oxide, zirconium oxide, niobium oxide, hafnium
oxide, tantalum oxide and tungsten oxide.
15. The electrode plate for display device according to claim 14,
wherein at least niobium oxide is selected to be added to the
cerium oxide which is the main material of said lower side
amorphous oxide layer.
16. The electrode plate for display device according to claim 14,
wherein said lower side amorphous oxide layer formed of an
amorphous or amorphous-like materials is formed of a mixed oxide
which contains at least niobium oxide mixed with cerium oxide.
17. The electrode plate for display device according to any one of
claims 1, 6, 9 and 14, wherein said silver-based layer is a silver
alloy containing at least one metal selected from a group of
platinum, palladium, gold, copper and nickel added to silver by not
larger than 3 at % (atomic percentage).
18. A method for manufacturing an electrode plate for display
device comprising the following steps of: forming a multi-layered
conductive film on a substrate, the multi-layered conductive film
comprising a lower side amorphous oxide formed of amorphous or an
amorphous-like oxide, an upper side amorphous oxide formed of an
amorphous or amorphous-like oxide and a silver-based layer which
held between the lower side amorphous oxide layer and the upper
side amorphous oxide layer, a film thickness of the upper side
amorphous oxide layer being not larger than 20 nm; forming an
electrode by patterning the oxide layers together with the
silver-based layer; and forming a protection layer on the
electrode, a film thickness of the protection layer being adjusted
to attain an optimum optical characteristic as the electrode.
19. The method for manufacturing the electrode plate for display
device according to claim 18, wherein said step of forming the
protection layer comprises a step of forming the protection layer
formed of an electrically insulating material on the electrode with
a sufficiently large film thickness for protection in a portion
other than an electrical connection portion of the electrode.
20. The method for manufacturing the electrode plate for display
device according to claim 18, wherein said electrode forming step
uses a,photolithography method using a photoresist, the photoresist
of the electrode portion for electrical connection is left behind
when the photoresist is selectively removed after the electrode
pattern is formed by use of the process of the photolithography
method, the photoresist left behind is used as mask for forming the
protection layer, and then the photoresist is removed to expose the
electrode portion for electrical connection from the protection
layer.
21. The method for manufacturing the electrode plate for display
device according to claim 18, wherein said pattern processing step
of effecting the patterning process is a mask sputtering
method.
22. A method for manufacturing an electrode plate for display
device comprising the following steps: forming a lower amorphous
oxide layer formed of an amorphous or amorphous-like material;
forming a silver-based layer on the lower oxide layer; and forming
an upper amorphous oxide layer formed of an amorphous or
amorphous-like material and having a film thickness not larger than
20 nm on the silver-based layer.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to an electrode plate which has a
substrate and a multi-layered conductive film and which can be
applied to a reflection preventing film, electromagnetic wave
shielding film, transparent type or reflective type electrode for
solar battery or electrode plate for a display device such as a
liquid crystal display device or EL (electroluminescence) display
device and a method for manufacturing the electrode plate.
[0002] A transparent electrode formed by arranging a transparent
conductive film for permitting light of predetermined electrode
pattern to pass therethrough on a glass substrate, plastic
substrate or substrate on which semiconductor elements are formed
is widely used for display electrodes of various types of display
devices such as a liquid crystal display, an input/output electrode
which permits an input to be directly effected on the display
screen of the display device and the like.
[0003] As a liquid crystal display device using the transparent
electrode, it is generally to use a transmission type liquid
crystal display device containing a light source (lamp) as a back
light. In the transmission type liquid crystal display device,
since the power consumption by the back light lamp is large and
thus the service life is short in the case of battery driving, the
portability which the liquid crystal display device originally has
cannot be fully utilized. For this reason, at present, a reflective
type liquid crystal display device using ambient light (that is,
containing no back light lamp) is actively developed.
[0004] FIG. 5 shows a reflective type liquid crystal display device
50 which is formed of a reflective type electrode plate 51 and a
transparent electrode plate 52 with sandwiching LCD 509. The
reflective electrode plate 51 is adhered to the transparent
electrode plate 52 via a seal 510 such that the transparent
electrode 507 faces the transparent electrode 505.
[0005] In the reflective electrode plate 51, a reflection film 502
and color filter 503 are sequentially formed on the surface of a
back substrate 501 comprised of, for example, glass which faces a
liquid crystal 509. A protection layer 504 for protecting and the
leveling the surface of the color filter 503 and a transparent
electrode 505 are sequentially formed on the color filter 503.
[0006] On one surface of the transparent plate, such as a glass
plate 511, a polarizing film 508 is laminated. On the other surface
of the glass plate 511, an array of transparent electrode 507 with
TFT (thin film transistor)s 506 is formed. The color filter 503 is
formed of plural pixels of light transmission type (which are
hereinafter simply referred to as pixels) colored in R (red), G
(green) and B (blue) and arranged in a predetermined pattern. The
reflection film 502 is also used as a reflection electrode which
can be used as a liquid crystal driving electrode in some
cases.
[0007] In the conventional case, a thin aluminum film is widely
used as the reflection film 502 formed on the back substrate 501.
This is because aluminum is a metal having a large reflectance of
light in the visible region, but recently, it is proposed to use
silver as a material of the reflection film from the viewpoint of
enhancement of the reflectance and a problem that a lowering in the
reflectance of aluminum due to contact with the liquid crystal or
glass substrate occurs.
[0008] However, the reflectance of silver itself is larger than
aluminum by approx. 10%, but it has the following main defects when
it is used to form a thin film of the electrode plate.
[0009] First, the adhearability thereof to the substrate of a
material such as glass or plastic is low and it is easily separated
from the substrate when it is formed on the substrate as a thin
silver film. Particularly, when an electrode is formed on the
substrate such as a glass plate, an SiO.sub.2 film is previously
formed on the substrate and a silver-based layer is formed on the
SiO.sub.2 film in some cases in order to prevent nebula of silver
(or prevent the silver-based layer from becoming slightly opaque)
due to migration of alkali metal from the substrate. At this time,
since the adhesion between the SiO.sub.2 film and the silver-series
thin film is poor, it is necessary to form an adhesion layer formed
of a thin oxide film between the SiO.sub.2 film and the
silver-series thin film. Therefore, the manufacturing process
becomes complicated and the manufacturing cost is increased.
[0010] Secondly, a silver-series thin film formed of highly pure
silver on the substrate tends to aggregate and become opaque by the
influence of heat and oxygen and the reflectance of light tends to
be lowered.
[0011] Thirdly, in a case where the thin silver film is exposed and
made in direct contact with the outside air, silver sulfide or
silver oxide is formed on the surface of the thin silver film and
the thin silver film becomes discolored and the reflectance thereof
is lowered.
[0012] Therefore, as the technique for solving the above problem
and defects, the technique for forming a three-layered conductive
film having a thin silver film disposed between oxide layers is
proposed in U.S. Pat. No. 5,667,853 by the inventors of this
invention.
[0013] In the above proposal, in a case where the transparent
electrode for the transmission type liquid crystal display device
is formed by use of the three-layered conductive film, the upper
side oxide layer (oxide layer formed on the upper surface of the
thin silver film) is formed in an amorphous state and the upper and
lower oxide layers are formed with a slightly large film thickness
of approx. 40 nm in order to attain the optimum optical
characteristic. The reason why the upper side oxide layer is formed
in the amorphous state is to prevent that silver atoms move along
the grain boundary when crystals or grains are present in the oxide
layer and the silver-based layer is aggregated or becomes opaque
and the reflectance or transmissivity is lowered.
[0014] However, the above proposal has the following problem.
[0015] When the three-layered conductive film of the above proposal
is patterned by the photolithography process by use of an etching
solution, contact corrosion due to contact between different types
of metals occurs, damage due to the etching process (particularly,
damage to the interface between the thin silver film and the oxide
film) is large, and particularly, the upper side oxide layer may be
easily separated.
[0016] Further, in order to form a stable amorphous film as the
oxide film, a mixed oxide layer having different types of oxide
materials mixed together is used in some cases. But in this case,
the electrical connection resistance of the conductive film becomes
high and it is not desirable as the conductive film. Further, as
described before, since damage to the interface between the thin
silver film and the oxide film occurs, the reliability such as
humidity resistance is greatly lowered and it does not reach the
practical level.
BRIEF SUMMARY OF THE INVENTION
[0017] This-invention is made to solve the above problem and an
object of this invention is to provide an electrode plate including
a transmission type or reflective type conductive film and having
an excellent optical characteristic (transmittance, reflectance),
low electrical connection resistance, good patterning configuration
and high reliability.
[0018] In the following description, the lower side amorphous or
amorphous-like oxide layer is an oxide layer which is one of the
oxide layers holding the silver-based layer therebetween and is
formed on the substrate before formation of the silver-based layer
and the upper side amorphous or amorphous-like oxide layer and
upper side oxide layer are oxide layers laminated on the
silver-based layer after formation of the silver-based layer.
[0019] (1) According to this invention, there is provided an
electrode plate for display device which includes a substrate and a
multi-layered conductive film, the multi-layered conductive film
including a silver-based layer, a lower side amorphous oxide layer
formed of an amorphous or amorphous-like material for suppressing
the movements of silver atoms at the interface with the
silver-based layer, and an upper side amorphous oxide layer formed
of an amorphous or amorphous-like material for suppressing the
movements of silver atoms at the interface with the silver-based
layer, the film thickness of at least the upper side amorphous
oxide layer being not larger than 20 nm.
[0020] With the above configuration, the upper side amorphous oxide
layer has a function for suppressing the movements of silver atoms
at the interface with the silver-based layer (it practically plays
a role as an anchor for fixing the movements of silver atoms) and
can suppress occurrence of aggregation and slight opaqueness caused
by the movements of silver atoms at high temperatures and a
lowering in the transmissivity or reflectance due to the
aggregation and slight opaqueness.
[0021] It is preferable that the upper side amorphous oxide layer
is an oxide layer in which the value of an optical film thickness
defined as the product of the film thickness and the refractive
index is 20 nm or less.
[0022] With the above configuration, the refractive index of the
upper side amorphous oxide layer can be set to a smaller value and
the reflectance can be enhanced when the electrode plate is formed
as the reflective type.
[0023] The electrode plate for display device has a protection
layer formed on the upper side amorphous oxide layer and it is
preferable that the sum of the optical film thicknesses of the
upper side amorphous oxide layer and the protection layer is 70 nm
or more. With the above configuration, the transmissivitys of the
upper side amorphous oxide layer and the protection layer can be
enhanced when the electrode plate is formed as the transmission
type.
[0024] The electrode plate for display device has a protection
layer formed on the upper side amorphous oxide layer. It is
preferable that the protection layer is formed of an oxide layer
having the refractive index equal to or smaller than that of the
upper side amorphous oxide layer and it is preferable that the
lower side amorphous oxide layer has an underlaid layer formed of
an oxide layer having the refractive index equal to or smaller than
that of the lower side amorphous oxide layer.
[0025] With the above configuration, the refractive indexes of the
upper side amorphous oxide layer and the lower side amorphous oxide
layer can be enhanced. As a result, the transmissivity can be
further enhanced when the electrode plate for display device is
formed as the transmission type.
[0026] It is preferable that the lower side amorphous oxide layer
of the electrode plate for display device is a mixed oxide which
contains cerium oxide as a main material and additionally contains
one or more oxide materials selected from a group of ytrium oxide,
zirconium oxide, niobium oxide, hafnium oxide, tantalum oxide and
tungsten oxide.
[0027] With the above configuration, the lower side amorphous oxide
layer has high adhesion with the silver-based layer and has an
alkali barrier effect for preventing migration of alkali metal such
as Na from the substrate which is a supporting member into the
silver-series thin film.
[0028] The electrode plate for display device is characterized in
that at least niobium oxide is used as the mixed oxide mixed with
the cerium oxide which is the main material of the lower side
amorphous oxide layer. It is characterized in that the lower side
amorphous oxide layer is formed of an amorphous or amorphous-like
mixed oxide which contains at least niobium oxide mixed with cerium
oxide.
[0029] With the above configuration, the lower side amorphous oxide
layer sufficiently prevents migrations of alkali metal such as Na
from the substrate into the silver-based layer and of silver atoms
to the interface of silver-series thin film. As a result, the
reliability can be enhanced.
[0030] In the electrode plate for display device, the silver-based
layer may be a silver alloy containing at least one metal selected
from a group of platinum, palladium, gold, copper and nickel added
to silver by 3 at % (atomic percentage) or less.
[0031] A conventional multi-layered film is added to silver by
larger than 3 at % (atomic percentage). However, with the above
configuration, since the silver-based layer is held between the
upper side amorphous oxide layer and the lower side amorphous oxide
layer, the substrate can be stably carried in the manufacturing
process such as the photolithography process and a protection layer
can be formed after formation of the pattern. As a result, an
additive amount of an alloy element added to silver can be
suppressed to minimum and the performance of the conductive film
can be further enhanced.
[0032] (2) According to this invention, there is provided an
electrode plate for display device which includes a substrate and a
multi-layered conductive film, the multi-layered conductive film
including a lower side amorphous oxide layer formed of an amorphous
or amorphous-like material for suppressing the movements of silver
atoms at the interface with the silver-based layer, a silver-based
layer, and an upper side oxide layer, the upper side oxide layer
including an oxide layer and an amorphous oxide layer formed of an
amorphous or amorphous-like material for suppressing the movements
of silver atoms at the interface with the silver-based layer and
the film thickness of the upper side amorphous oxide layer being
not larger than 20 nm.
[0033] With the above configuration, the upper side oxide layer and
the lower side amorphous oxide layer have a function for
suppressing the movement of silver atoms at the interface with the
silver-based layer (it practically plays a role as an anchor for
fixing the movements of silver atoms) and can suppress occurrence
of aggregation and slight opaqueness caused by the movements of
silver atoms at high temperatures and a lowering in the
transmissivity or reflectance due to the aggregation and slight
opaqueness.
[0034] It is preferable that the value of an optical film thickness
defined as a product of the film thickness and a refractive index
of the amorphous oxide layer included in the upper side oxide layer
is not larger than 20 nm or less.
[0035] With the above configuration, the refractive index of the
amorphous oxide layer can be lowered and the reflectance can be
enhanced when the electrode plate is formed as the reflective
type.
[0036] It is preferable that the electrode plate for display device
has a protection layer formed on the upper side oxide layer and the
sum of the optical film thicknesses of the upper side oxide layer
and the protection layer is 70 nm or more.
[0037] With the above configuration, the transmissivitys of the
upper side oxide layer and the protection layer can be enhanced
when the electrode plate is formed as the transmission type.
[0038] The electrode plate for display device has a protection
layer formed on the upper side oxide layer and it is preferable
that the protection layer is an oxide layer having the refractive
index equal to or smaller than that of the amorphous oxide layer
and it is preferable that the lower side amorphous oxide layer has
an underlaid layer formed of an oxide layer having the refractive
index equal to or smaller than that of the lower amorphous oxide
layer.
[0039] With the above configuration, the refractive indexes of the
amorphous oxide layer and the lower side amorphous oxide layer can
be enhanced, and as a result, the transmissivity can be further
enhanced when the electrode plate for display device is formed as
the transmission type.
[0040] It is preferable that the lower side amorphous oxide layer
of the electrode plate for display device is formed of a mixed
oxide which contains cerium oxide as a main material and
additionally contains one or more oxide materials selected from a
group of ytrium oxide, zirconium oxide, niobium oxide, hafnium
oxide, tantalum oxide and tungsten oxide.
[0041] With the above configuration, the lower side oxide layer has
high adhesion with the silver-series thin film and has an alkali
barrier effect for preventing migration of an alkali metal such as
Na from the substrate which is a supporting member into the
silver-series thin film.
[0042] The electrode plate for display device is characterized in
that at least niobium oxide is used as the mixed oxide added to the
cerium oxide which is the main material of the lower side amorphous
oxide layer. It is characterized in that the lower side amorphous
oxide layer is formed of an amorphous or amorphous-like mixed oxide
which contains at least niobium oxide mixed with cerium oxide.
[0043] With the above configuration, the lower side oxide layer
sufficiently prevents migration of alkali metal such as Na from the
substrate and of silver to the interface of silver-series thin
film. As a result, the reliability can be enhanced.
[0044] The electrode plate for display device is characterized in
that the silver-based layer may be formed of a silver alloy
containing at least one metal selected from a group of platinum,
palladium, gold, copper and nickel added to silver by 3 at %
(atomic percentage) or less.
[0045] A conventional multi-layered conductive film has more than 3
at % materials added to silver to stabilize the movement of silver.
However with the above configuration, since the silver-based layer
is held between the lower side amorphous oxide layer and the upper
side amorphous oxide layer, the substrate is not affected by the
manufacturing process such as the photolithography process and thus
a protection layer can be formed after formation of the pattern. As
a result, an additive amount of an alloy element added to silver
can be suppressed to minimum and the performance of the conductive
film can be further enhanced.
[0046] (3) According to this invention, there is provided a method
for manufacturing an electrode plate for display device comprising
the following steps of forming a multi-layered conductive film on a
substrate, the multi-layered conductive film comprising a lower
side amorphous oxide formed of amorphous or an amorphous-like
oxide, an upper side amorphous oxide formed of an amorphous or
amorphous-like oxide and a silver-based layer which held between
the lower side amorphous oxide layer and the upper side amorphous
oxide layer, a film thickness of the upper side amorphous oxide
layer being not larger than 20 nm; forming an electrode by
patterning the oxide layers together with the silver-based layer
and forming a protection layer on the electrode, a film thickness
of the protection layer being adjusted to attain an optimum optical
characteristic as the electrode.
[0047] According to this invention, there is provided a method for
manufacturing an electrode plate for display device comprising the
following steps forming a lower amorphous oxide layer formed of an
amorphous or amorphous-like material forming a silver-based layer
on the lower amorphous oxide layer and forming an upper amorphous
oxide layer formed of an amorphous or amorphous-like material and
having a film thickness not larger than 20 nm on the silver-based
layer.
[0048] With the above configuration, since the photolithography
process can be effected when the conductive film is formed in a
predetermined electrode pattern, the etching process can be easily
effected, no damage to the interface portion between the amorphous
oxide layer and the silver-based layer due to the etching process
occurs and the patterning process can be effected with high
precision.
[0049] In the method for manufacturing the electrode plate for
display device, it is preferable that the step of forming the
protection layer is a step of forming the protection layer made of
an electrical insulating material on the electrode with a
sufficiently large film thickness for protection in a portion other
than the electrical connection portion of the electrode.
[0050] With the above configuration, since the protection layer has
an electrically insulating property, the electrical short circuit
between the facing substrates can be prevented. Therefore, the
abnormal operation due to the electrical short circuit can be
prevented.
[0051] In the method for manufacturing the electrode plate for
display device, it is preferable that the pattern processing step
of effecting the patterning process is a photolithography method
using a photoresist, the resist in the electrode portion for
electrical connection is left behind when the photoresist is
selectively removed after the electrode pattern is formed in the
process of the photolithography method, and the resist left behind
is used as a mask for forming the protection layer, then the resist
is removed to expose the electrode portion for electrical
connection from the protection layer. Further, it is preferable
that the pattern processing step of effecting the patterning
process is a mask sputtering method.
[0052] With the above configuration, if the photolithography method
using the photoresist is used as the method for selectively forming
the protection layer on the electrode plate, selection with the
high precision can be attained and a manufacturing method suitable
for a highly precise pattern of a liquid crystal display device or
the like can be attained, and if the mask sputtering method is
used, the protection layer can be easily formed with a precision
slightly lower than that of the photolithography method and a
manufacturing method suitable for a relatively rough pattern of a
solar battery or the like can be attained.
[0053] Additional objects and advantages of the present invention
will be set forth in the description which follows, and in part
will be obvious from the description, or may be learned by practice
of the present invention.
[0054] The objects and advantages of the present invention may be
realized and obtained by means of the instrumentalities and
combinations particularly pointed out hereinafter.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0055] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate presently
preferred embodiments of the present invention and, together with
the general description given above and the detailed description of
the preferred embodiments given below, serve to explain the
principles of the present invention in which:
[0056] FIG. 1 is a view showing the schematic structure of an
electrode plate according to a first embodiment of this
invention;
[0057] FIG. 2 is a view showing the schematic structure of an
electrode plate according to a second embodiment of this
invention;
[0058] FIG. 3 is a view showing the schematic structure of an
electrode plate according to a third embodiment of this
invention;
[0059] FIG. 4 is a view showing the schematic structure of an
electrode plate according to fourth and fifth embodiments of this
invention; and
[0060] FIG. 5 is a view showing the schematic structure of a
conventional reflective type liquid crystal display device.
DETAILED DESCRIPTION OF THE INVENTION
[0061] There will now be described first to fifth embodiments of
this invention with reference to the accompanying drawings.
[0062] In the electrode plate for display device according to this
invention, the silver-based layer included in a multi-layered
conductive film forms a preferable reflection electrode when the
film thickness of the silver-based layer is set to approx. 100 to
200 nm or more and forms a preferable transparent electrode when
the film thickness of the silver-based layer is set in a range of
approx. 7 to 25 nm.
First Embodiment
[0063] FIG. 1 is a view showing the schematic structure of an
electrode plate according to a first embodiment of this
invention.
[0064] In FIG. 1, the main portion of an electrode plate 9
according to the first embodiment is constructed by a glass
substrate 10 (made by Corning Co. 1737 material) with a thickness
of 0.7 mm and an underlaid layer 1 with a thickness of 29 nm, a
lower side amorphous oxide layer 2 with a thickness of 10 nm (as
will be seen later, the lower side amorphous oxide function as a
lower side anchoring layer), a silver-based layer 3 with a
thickness of 15 nm, an upper side amorphous oxide layer 4 with a
thickness of 10 nm (as will be seen later, the upper side amorphous
oxide function as an upper side anchoring layer) and a protection
layer 5 with a thickness of 29 nm which are sequentially laminated
on the glass substrate 10. The lower side amorphous oxide layer 2,
thin silver-based layer 3, and upper side amorphous oxide layer 4
form a multi-layered conductive film.
[0065] In the above configuration, if the glass substrate 10 is a
soda glass substrate, the underlaid layer 1 has a function of an
alkali barrier effect. Further, if an adherence between a substrate
and an oxide layer is weak, the underlaid layer 1 has also a
function of adherence layer for adhering between the substrate and
the oxide.
[0066] The electrode plate 9 according to the first embodiment is a
light transmission type electrode plate since the film thickness of
the silver-based layer 3 is 15 nm (which lies in a range of approx.
7 to 25 nm).
[0067] The electrode plate 9 according to the first embodiment is
formed by the following manufacturing process.
[0068] That is, first, the glass plate 10 which has been cleaned is
inserted into a vacuum chamber (sputtering chamber) and a vacuum is
drawn.
[0069] Next, the underlaid layer 1 is laminated and formed on the
glass plate 10 by the sputtering method.
[0070] Then, the glass plate 10 is taken out from the vacuum
chamber (sputtering chamber) and is heated at 300.degree. C. for
one hour to be subjected an anneal process. The glass plate 10 is
again inserted into the vacuum chamber (sputtering chamber) and a
vacuum is drawn. The lower side amorphous oxide layer 2,
silver-based layer 3, and upper side amorphous oxide layer 4 are
sequentially laminated and formed on the underlaid layer 1 by the
sputtering method.
[0071] Then, the resultant glass plate 10 is taken out from the
vacuum chamber (sputtering chamber) and a resist pattern (not
shown) having a predetermined pattern (for example, stripe pattern)
is formed on the upper side oxide layer 4 by the photolithography
process. Next, sulfuric acid-series etchant containing nitric acid
and iron nitrate by 1 weight % is used as an etching solution to
simultaneously remove portions of the three layers of the lower
side amorphous oxide layer 2, the silver-based layer 3 and the
upper side amorphous oxide layer 4 which lie in an exposed portion
from the resist pattern by etching.
[0072] Next, after a resist pattern portion corresponding to a
display plane 16 shown in FIG. 1 is exposed again (at this time, a
terminal portion 17 is not exposed), the resist pattern portion in
the portion of the display plane 16 is removed by use of an organic
alkali solution.
[0073] Next, the protection layer 5 is formed on the entire surface
of the glass substrate 10 by use of the sputtering chamber.
[0074] Then, after the substrate is exposed again, the resist
pattern lying on the terminal portion 17 is removed by use of the
organic alkali solution, and then, the anneal process (heat
treatment) for heating the substrate at the temperature of
200.degree. C. for one hour is effected to obtain the electrode
plate 9 of the first embodiment.
[0075] In the above manufacturing process, the underlaid layer 1
and protection layer 5 are each formed by use of a sputtering
target formed of a mixed oxide material containing tin oxide,
cerium oxide and gallium oxide. The composition of the sputtering
target included tin 80 at % (atomic percentage), cerium 10 at %
(atomic percentage) and gallium 10 at % (atomic percentage) in
terms of the atomic percentage of metal elements (an oxygen element
is not counted).
[0076] Next, the lower side amorphous oxide layer 2 and upper side
oxide layer 4 are each formed by use of a sputtering target formed
of a mixed oxide material containing indium oxide, cerium oxide,
tin oxide and titanium oxide and the composition of the sputtering
target included indium 88 at %, cerium 8.5 at %, tin 3 at % and
titanium 0.5 at % in terms of the atomic percentage of metal
elements (an oxygen element is not counted).
[0077] Further, the composition of an alloy target used for forming
the silver-series thin film 3 included silver 98.5 at %, gold 1 at
% and copper 0.5 at %.
[0078] The inventors of this invention formed films to a film
thickness of 100 nm by use of the same materials as the protection
layer 5 (or the underlaid layer 1) and the lower side amorphous
oxide layer 2 (or the upper side amorphous oxide layer 4) and
measured the refractive indexes of the films. As the result, it was
understood that the refractive index of the former film was 2.06
and the refractive index of the latter film was 2.10 at the
wavelength of 550 nm.
[0079] The sum of the optical film thickness (the product of the
film thickness and the refractive index) of the protection layer 5
(or the underlaid layer 1) with a film thickness of 29 nm and the
optical film thickness of the upper side oxide layer 4 (or the
lower side amorphous oxide layer 2) was
(29.times.2.06+10.times.2.17)=(59.74+21.0)=80.74 nm.
[0080] Under the above optical characteristics, it was confirmed
that the transmissivity of the electrode plate 9 at the wavelength
of 550 nm was set to 96% (the transmissivity of the single layer of
the glass substrate 10 was used as a reference) on the display
surface portion 16 on which the protection layer 5 was formed and
thus a relatively large transmissivity was obtained.
[0081] Therefore, if each of the protection layer 5, lower side
amorphous oxide layer 2 and upper side amorphous oxide layer 4 is
formed with the above-described materials, the composition of the
above materials and the film thicknesses, the refractive index and
optical film thicknesses described above can be attained and the
electrode plate with large transmissivity can be obtained.
[0082] Further, since the lower side amorphous oxide layer 2 and
upper side amorphous oxide layer 4 for holding the silver-based
layer 3 therebetween are both formed of amorphous, occurrence of
aggregation and slight opaqueness caused by the movement of silver
at the interface with the silver-based layer and a lowering in the
transmissivity due to the aggregation and slight opaqueness can be
suppressed.
[0083] The reason that each of the upper side amorphous oxide layer
and the lower side amorphous oxide layer has above function is the
following.
[0084] An atom of silver is easy to move on the surface with the
silver-based layer. If the silver-based layer under exposing in air
is heated at the temperature lied in range of approx. 200 to
300.degree. C., the atoms of the silver diffuses and moves to the
interface with the silver-based layer. The resulting atoms of the
silver re-crystallize, grow and finally become clods of the silver.
The clods of the silver causes aggregate and opaque at the
interface with the silver-based layer and the reflectance of the
silver-based layer is lowered. Note that if the interface with the
silver-based layer (the respective surfaces of minute silver
crystals before re-crystallization) is planted so-called cores of
some molecular of oxide by sputtering method and the like, the
cores act as anchors for suppressing the movement of the atoms of
silver, prevent the atoms of silver from diffusing to the interface
with the silver-based layer, suppress re-crystallization of the
atoms of silver at the interface with the silver-based layer and
prevent optical characteristic of the silver-based layer from
deteriorating.
[0085] Rows of the cores of the oxide planted at the interface with
the silver-based layer are the upper side amorphous oxide layer and
the lower side amorphous oxide layer. That is, the upper side
amorphous oxide layer and the lower side amorphous oxide layer can
be called "anchoring layer" for fixing the movement of the silver
at the interface with the silver-based layer like "anchor".
[0086] Therefore, the lower side amorphous oxide layer functions as
a lower side anchoring layer and the upper side amorphous oxide
layer functions as an upper side anchoring layer.
[0087] Note that viewing of the reliance, it is preferable that
electrochemical characteristic (for example, potential of corrode)
between the anchoring layer and the silver-based layer is close and
the anchoring layer is amorphous or amorphous-like to suppress the
diffusing of the silver at the interface with the silver-based
layer. Further, it is necessary that the adherence between the
anchoring layer and the silver-based layer is strong.
[0088] Further, it is preferable that the upper/lower side
amorphous oxide layer is transparent materials of high resistance
to alkali and at least the upper side amorphous oxide layer is
soluble in etchant which is acid and the like used by etching.
[0089] Note that if the electrode plate of present invention
applied for a display device used in a liquid crystal display
device is used an electrode plate for driving liquid crystal, it is
preferable that the anchoring layer is made of mixed oxide having
basic conductive oxide materials.
[0090] Further, as shown in FIG. 1, a multi-layered film including
the lower side amorphous oxide layer 2, the silver-based layer 3
and the upper side amorphous oxide layer 4 has three layered
structure including the silver-based layer held between the lower
side amorphous oxide layer 2 as the anchoring layer and the upper
side amorphous oxide layer 4 as the anchoring layer. However, as
will seen later in the third embodiment, from the viewing of
optical characteristic, it is possible that the lower side
amorphous oxide layer 2 or the upper side amorphous oxide layer 4
is a multi-layered film including transparent oxide film laid on an
anchoring layer. Further, it is possible to select the above
configurations of the multi-layered conductive film depending on an
application of the film.
[0091] Further, since the lower side amorphous oxide layer 2 and
upper side amorphous oxide layer 4 for holding the silver-based
layer 3 therebetween are both formed of amorphous, occurrence of
aggregation and slight opaqueness caused by the movement of silver
at the interface with the silver-based layer and a lowering in the
reflectance due to the aggregation and slight opaqueness can be
suppressed.
[0092] Further, in the terminal portion 17, it is possible to make
electrical connection with a low electrical resistance to the
silver-based layer 3 via the upper side amorphous oxide layer 4
with a thin film thickness. The protection layer 5 on the display
surface potion 16 can be used as a good insulating protection layer
(the protection layer 5 is used as a film for preventing the
electrical short circuit with respect to the facing substrate in a
liquid crystal display device such as an STN) and the electrode
plate with an electrically high reliability can be obtained.
[0093] In this case, the lower side amorphous oxide layer 2 and
upper side amorphous oxide layer 4 for holding the silver-based
layer 3 therebetween are both formed to a film thickness of 10 nm
and it is considered that the critical value of the film thickness
is not larger than 20 nm in order to attain the same effect. The
result is derived by checking the degree to damage at the interface
between the silver-based layer and the oxide layer caused by the
photolithography process (the time of etching) from the viewpoint
of a change in the connection resistance in the high temperature
and the high humidity and determining the film thickness.
[0094] That is, a variation in the connection resistance was
observed by variously changing the film thickness under the general
condition (it was left for 1000 hours in an atmosphere of
temperature 70.degree. C. and humidity 95%) set in the endurance
test. As the result, it is found that the stability of the
connection resistance could be obtained when the film thicknesses
of the upper side amorphous oxide layer 4 and the lower side
amorphous oxide layer 2 are set to 20 nm or less, and more
preferably, 10 nm or less.
[0095] Further, the total sum of the optical film thickness of the
protection layer 5 (or the underlaid layer 1) and the optical film
thickness of the upper side oxide layer 4 (or the lower side
amorphous oxide layer 2) with a film thickness of 10 nm was set to
80.74 nm, but the same effect can be attained if the total sum is
set to 70 nm or more. The reason is as follows.
[0096] When the film thicknesses of the upper side amorphous oxide
layer 4 and the lower side amorphous oxide layer 2 holding the
silver-based layer therebetween are set to 20 nm or less, the
reflected light component from the silver-based layer becomes
stronger and the sufficiently large transmissivity cannot be
attained. For example, in the three-layered conductive film having
the silver-based layer held between oxide layers with the
refractive index of approx. 2, it is difficult to attain a large
transmissivity unless the film thicknesses of the upper side
amorphous oxide layer 4 and the lower side amorphous oxide layer 2
are set to approx. 40 to 45 nm.
Second Embodiment
[0097] FIG. 2 is a view showing the schematic structure of an
electrode plate according to a second embodiment of this
invention.
[0098] In FIG. 2, the main portion of an electrode plate 19 is
formed by forming an underlaid layer 21 formed of SiO.sub.2 with a
film thickness of 40 nm on a glass substrate 20 (made by NIHON
ITAGARASU KABUSHIKI KAISHA, H coat product) with a film thickness
of 0.7 mm and then sequentially laminating a lower side amorphous
oxide layer 22 (a lower side anchoring layer) with a film thickness
of 20 nm, a silver-based layer 23 with a film thickness of 150 nm,
and an upper side amorphous oxide layer 24 (an upper side anchoring
layer) with a film thickness of 7 nm. The lower side amorphous
oxide layer 22, thin silver-series thin film 23, and upper side
amorphous oxide layer 24 form a multi-layered conductive film.
[0099] The electrode plate 19 according to the second embodiment is
a reflective type electrode plate since the film thickness of the
silver-based layer 23 is 150 nm (approx. 100 to 200 nm).
[0100] The electrode plate 19 according to the second embodiment is
formed by the following manufacturing process.
[0101] First, the glass plate 20 which is cleaned is inserted into
a vacuum chamber (sputtering chamber) and a vacuum is drawn.
[0102] Next, the underlaid layer 21 is laminated by the sputtering
method. Next, the grass substrate 20 is taken out from the vacuum
chamber (sputtering chamber), the anneal process (heat treatment)
for heating the grass substrate 20 at the temperature of
300.degree. C. for one hour is effected. Next, the grass substrate
is inserted into a vacuum chamber (sputtering chamber) and a vacuum
is drawn. Next, lower side amorphous oxide layer 22, silver-based
layer 23 and upper side amorphous oxide layer 24 are continuously
laminated by the sputtering method.
[0103] Then, the glass plate 20 is taken out from the vacuum
chamber and a resist pattern having a preset pattern is formed on
the upper side amorphous oxide layer 24 by the photolithography
process. Next, sulfuric acid-series etchant containing nitric acid
and iron nitrate by 1 weight % is used as an etching solution to
simultaneously remove portions of the three layers of the lower
side amorphous oxide layer 22, silver-based layer 23 and upper side
oxide layer 24 which lie in an exposed portion from the resist
pattern by etching.
[0104] Next, after the entire surface of the resist pattern is
exposed again, the resist pattern is removed by use of an organic
alkali solution. After this, the anneal process (heat treatment)
for heating the substrate at the temperature of 200.degree. C. for
one hour is effected to obtain the electrode plate 19 of the second
embodiment.
[0105] In the above manufacturing process, the underlaid layer 21
is formed by use of a sputtering target formed of silicon oxide
(SiO.sub.2) and has a function as the alkali barrier layer.
Further, the lower side amorphous oxide layer has a function of an
adhesive layer between underlaid layer 21 and the silver-based
layer 23.
[0106] The composition of the target used for formation of the
lower side amorphous oxide layer 22 and upper side oxide layer 24
includes indium oxide 77 at %, cerium oxide 20 at % and zinc oxide
3 at % in terms of the atomic percentage of metal elements (an
oxygen element is not counted). Further, the composition of the
alloy target used for forming the silver-based layer 23 includes
silver 98.5 at %, gold 1 at % and copper 0.5 at %.
[0107] The inventors of this invention measured the refractive
index of the upper-side amorphous oxide layer 24 by use of the same
material and composition and found that the refractive index was
1.447 at the wavelength of 550 nm and was 1.488 at the wavelength
of 430 nm. The upper side amorphous oxide layer 24 was formed thin
with a film thickness of 7 nm (no laminated layer of oxide is
formed thereon) and the refractive index thereof is smaller than
that of the bulk.
[0108] The reflectance of a multi-layered conductive film formed of
the silver-based layer 23 and the upper side amorphous oxide layer
24 was measured by use of the integrating sphere with barium
sulfate used as a reference and the result showed that the
refractive index was 96% at the wavelength of 550 nm and 88% at the
wavelength of 430 nm and was thus large. Further, the optical film
thickness of the upper side amorphous oxide layer 24 with the film
thickness of 7 nm and the refractive index of 1.447 (wavelength 550
nm) was 7.times.1.447=10.129 nm.
[0109] Depending on the materials of the silver-based layer and the
amorphous oxide layers and the surface condition of the ground
layer (for example, substrate or the like), the oxide is not formed
in the uniform film form but formed in the island form when the
film thickness of the upper side amorphous oxide layer 24 is set in
the range of 2 to 10 nm, and the film includes voids and the
refractive index of the film is smaller than that of the bulk from
the optical viewpoint. As a result, the reflectance and an optical
characteristic are heightened.
[0110] Further, the optical film thickness (the product of the film
thickness and the refractive index) of the upper side amorphous
oxide layer 24 was 10.129 nm, but it is considered that the
critical value of the film thickness is not larger than 20 nm in
order to attain the same effect. The result is derived by comparing
the reflectance of the reflective type electrode plate using the
silver-based layer with the reflectance of the reflective type
electrode plate using the aluminum thin film from the viewpoint of
optical characteristics and making a determination based on the
comparison result.
[0111] That is, the reflectance of silver is larger than that of
aluminum by approx. 10% and may be a good metal, but the
reflectance thereof on the short wavelength side tends to become
smaller depending on the additive amount of an alloy element to
silver or the film thickness of the upper side amorphous oxide
layer 24 or the lower side amorphous oxide layer 22.
[0112] For example, the reflectance of aluminum for light of 430 nm
(the wavelength of the blue range) is approx. 85%. Therefore, in
order to provide an electrode plate more excellent than the
conventional case, it is necessary to attain the reflectance of
approx. 85% or more at the wavelength of 430 nm in the electrode
plate of this invention using the silver-based layer. The inventors
of this invention derived from various studies that the reflectance
of approx. 85% or more could be obtained at the wavelength of 430
nm if the optical film thickness of the oxide layer was 20 nm or
less in terms of the value of the optical film thickness which is
the product of the film thickness (the unit is nm) and the
refractive index.
[0113] However, as described before, in the thin film region, the
refractive index of the oxide layer is smaller than that of the
bulk.
[0114] The upper side amorphous oxide layer 24 and the lower side
amorphous oxide layer 22 have a function as an anchor fixing the
movement of silver at the interface with the silver-based layer,
but when the film thickness is considered for the function from the
viewpoint of high temperature heat resistance, the function can be
fully attained even if the film thickness is approx. 1 nm.
[0115] If the above film thickness is set, the advantage that the
etching time is reduced and damage to the interface caused by the
etching can be reduced by the reduction in the etching time can be
attained, but it is preferable to set the lower limit of the film
thickness to 2 nm or more since the film is somewhat unstable from
the viewpoint of the manufacturing process when a variation in the
film thickness at the time of formation of the film and wash-away
at the time of cleaning using an alkali solution or the like are
taken into consideration.
[0116] In order to check the durability of the optical
characteristics of the electrode plate 19 with the above-described
materials, the composition of the materials and the thickness and
the electrode plate 9 according to the first embodiment, the
electrode plates were stored for 1000 hours in a high-temperature
and high-humidity chamber in which the temperature was set at
70.degree. C. and the humidity was set at 95% and variations in the
optical characteristics were checked. As the result, it was found
that variations in the optical characteristics (transmissivity or
reflectance) and the adhesive properties of the electrode patterns
were not observed and the reliability (durability) was extremely
preferable.
[0117] Therefore, according to the electrode plates 9 and 19, a
highly endurable electrode can be realized.
[0118] Further, in order to check the heat resistance of the
electrode plate 19 with the above-described materials, the
composition of the materials and the thickness and the electrode
plate 9 according to the first embodiment, the electrode plates 9
and 19 were heated for one hour at the temperature of 250.degree.C.
or heated for one hour at the temperature of 300.degree. C. and the
heat resistance of each of the electrode plates 9 and 19 was
checked. As the result, it was found that a variation in the heat
resistance was not observed as in the durability and the electrode
plates had the excellent heat resistance.
[0119] Therefore, according to the electrode plates 9 and 19, a
highly endurable electrode can be realized.
[0120] Further, in order to check the resistance to alkali of the
electrode plate 19 with the above-described materials, the
composition of the materials and the thickness and the electrode
plate 9 according to the first embodiment, the electrode plates 9
and 19 were dipped in an alkali solution (containing NaOH by 1
weight %) at the temperature of 40.degree. C. for 10 minutes and
the resistance to alkali was checked, but no variation was observed
and it was proved that the electrode plate 9 according to the first
embodiment and the electrode plate 19 had the sufficiently high
resistance to alkali in practice.
[0121] Therefore, according to the electrode plates 9 and 19, an
electrode which has the high resistance to alkali can be
realized.
[0122] Further, since the lower side amorphous oxide layer 22 and
upper side oxide layer 24 for holding the silver-based layer 23
therebetween are both formed of amorphous, occurrence of
aggregation and slight opaqueness caused by the movement of silver
at the interface with the silver-based layer and a lowering in the
reflectance of the silver-based layer 23 due to the aggregation and
slight opaqueness can be suppressed.
[0123] Further, the each connection resistance of the electrode
plate 19 according to the second embodiment and the electrode plate
9 according to the first embodiment was measure by taking the
electrical mounting on the liquid crystal display device such as
STN (the evaluation was made by applying a needle of
berylium-copper alloy) and it was found that the connection
resistance was approx. 0.5 to 1.OMEGA. and the connection
resistance was lower than that of the transparent electrode (ITO)
which was normally used.
[0124] Therefore, according to the electrode plate 19 and the
electrode 9 with the above-described materials, the composition of
the materials and the thickness, the electrodes which are also
excellent in the connection resistance can be obtained.
Third Embodiment
[0125] As shown in FIG. 3, an electrode plate 30 according to a
third embodiment of this invention has a laminated film 37 formed
on a glass substrate 31 having an SiO.sub.2 (silicon oxide) layer
coated on the surface thereof and having an alkali barrier
function. The laminated film 37 is formed of a lower side amorphous
oxide layer 32, silver-based layer 33 and upper side oxide layer 34
and the upper side oxide layer 34 is a multi-layered layer having a
first amorphous oxide layer 35 (anchoring layer) and a second
amorphous oxide layer 36 laminated on the first amorphous oxide
layer 35. The film thickness of the lower side amorphous oxide
layer 32 is set to 25 nm, the film thickness of the silver-based
layer 33 is set to 15 nm, the film thickness of the amorphous oxide
layer 35 is set to 10 nm, and the film thickness of the second
amorphous oxide layer 36 is set to 30 nm. The lower side amorphous
oxide layer 32, silver-based layer 33, and upper side oxide layer
34 form a multi-layered conductive film.
[0126] The electronic plate 30 according to the third embodiment is
a light transmission type electronic plate since the thin film of
the silver-based layer 33 is 15 nm.
[0127] In this case, the lower side amorphous oxide layer 32 is
formed of a mixed oxide material which contained cerium oxide as a
main material and additionally contained niobium oxide by 15 at %
in terms of the at % (atomic percentage) only of the metal atom
which did not include the oxygen atom. The amorphous oxide layer 35
is formed of a mixed oxide material containing indium oxide, cerium
oxide, tin oxide and titanium oxide and the composition thereof
contained indium oxide 88 at % (atomic percentage), cerium oxide
8.5 at % (atomic percentage),tin oxide 3.0 at % (atomic percentage)
and titanium oxide 0.5 at % 8 (atomic percentage) in terms of the
at % (atomic percentage), only of the metal atom which did not
include the oxygen atom. The second amorphous oxide layer 36 is
formed of a mixed oxide material which contained cerium oxide as a
main material and additionally contained niobium oxide by 15 at %
in terms of the at % (atomic percentage) only of the metal atom
which do not include the oxygen atom. The silver-based layer 33 is
formed of a silver alloy having gold and copper added to silver and
the composition thereof contained silver 98.5 at % (atomic
percentage), gold 1.0 at % (atomic percentage) and copper 0.5 at %
(atomic percentage).
[0128] The electrode plate 30 according to the third embodiment is
formed by the following manufacturing process.
[0129] First, the soda glass substrate 31 is subjected to the
degreasing, cleaning and drying process and then put into the
sputtering chamber, and a voltage is applied to a mixed oxide
(cerium oxide and niobium oxide) target having the above-described
composition to form a lower side amorphous oxide layer 32 on the
soda glass substrate 31 by RF (high frequency) sputtering.
[0130] The atmosphere set in the sputtering chamber is the same as
that set at the time of formation of the lower side oxide thin film
in the forth embodiment described later (that is, the gas pressure
of the mixed gas of Ar and O.sub.2 was set at 0.35 Pa and the
percentage of O.sub.2 was set at 10%).
[0131] When the step of forming the lower side amorphous oxide
layer 32 is completed, discharging and introduction of gas are
stopped and a vacuum is drawn to the vacuum degree
5.times.10.sup.-4 Pa in the sputtering chamber.
[0132] Next, Ar gas is introduced into the sputtering chamber to
adjust the gas pressure to 0.4 Pa and a voltage is applied to a
silver alloy (silver, gold, copper) target with the above
composition to form a silver-based layer 33 by DC (direct current)
sputtering.
[0133] When the step of forming the silver-based layer 33 is
completed, discharging and introduction of gas are stopped and a
vacuum are drawn to the vacuum degree 5.times.10.sup.-4 Pa in the
sputtering chamber.
[0134] Next, a voltage is applied to a mixed oxide (indium oxide
and cerium oxide) target with the above composition to form an
amorphous oxide layer 35 on the silver-based layer 33 by DC (direct
current) sputtering. At this time, the atmosphere set in the
sputtering chamber is the same as that set at the time of formation
of the upper side amorphous oxide thin film 44 in the forth
embodiment (that is, the mixed gas pressure of Ar and O.sub.2 is
set at 0.35 Pa and the percentage of O.sub.2 was set at 0.75%).
[0135] Next, the soda glass substrate 31 is taken out from the
sputtering chamber and a photolithography process from the step of
coating the photosensitive resin (positive resist) to the step of
separating the photosensitive resin pattern is effected for the
soda glass substrate 31 in the same manner as in the forth
embodiment to form the silver-based layer 33 and amorphous oxide
layer 35 in a preset electrode pattern.
[0136] At the time of etching, the lower side amorphous oxide layer
32 is not etched and remain in the same film form as it was
formed.
[0137] Next, the soda glass substrate 31 is put into the sputtering
chamber again and the sputtering chamber is evacuated, and then a
voltage is applied to a mixed oxide (cerium oxide and niobium
oxide) target having the above-described composition to form a
second amorphous oxide layer 36 on the substrate 31 by RF (high
frequency) sputtering. The RF sputtering is carried out by mask
sputtering the second amorphous oxide layer 36 is formed in a
predetermined area except the terminal portion of the electrode
pattern. Further, the atmosphere set in the sputtering chamber is
the same as that set at the time of formation of the lower side
oxide thin film 42 in the forth embodiment (that is, the mixed gas
pressure of Ar and O.sub.2 is set at 0.35 Pa and the percentage of
O.sub.2 was set at 10%).
[0138] Next, the substrate on which the second amorphous oxide
layer 36 is formed is subjected to the drying process at
180.degree. C. for one hour to obtain the electrode plate 30 as
shown in FIG. 3.
[0139] During the film formation by sputtering, the substrate is
not heated and film formation is continuously effected with the
vacuum condition kept.
[0140] In order to check the electrical stability of the electrode
plate 30 having the thin films with the above-described materials,
the composition of the materials and the thicknesses, the
electrical short circuit between the electrode patterns was checked
by use of a wiring tester, but the electrical short circuit between
the electrode patterns by the lower side amorphous oxide layer 32
which was not etched and remained was not observed.
[0141] Therefore, with the above structure, the electrode plate
with high electrical stability can be realized.
[0142] Further, the transmissivity of the electrode plate 30
obtained in the third embodiment was 70% or more at the wavelength
(400 to 700 nm) of the visible region and was sufficiently large
and the area resistance was a low resistance of 2.7
.OMEGA./.quadrature..
[0143] Therefore, according to the lower side amorphous oxide layer
32 and upper side oxide layer 34 with the above-described
materials, composition and thickness, the electrode plate with the
large transmissivity and low resistance can be realized.
[0144] Further, since the lower side amorphous oxide layer 32 and
the amorphous oxide layer 35 which hold the silver-based layer 33
therebetween are both formed of amorphous, occurrence of
aggregation and slight opaqueness caused by the movement of silver
at the interface with the silver-based layer and a lowering in the
transmissivity of the silver-based layer 33 due to the aggregation
and slight opaqueness can be suppressed.
[0145] Further, the amorphous oxide layer 36 according to the third
embodiment is an amorphous material. However, since the amorphous
oxide layer 36 functions as heightening a transmission by
adjustment of the refractive index and a protection layer of the
silver-based layer 33, the amorphous oxide layer 36 is not
necessarily limited to be amorphous.
[0146] The laminated film 37 obtained in the third embodiment is
formed as a transparent electrode, which makes the laminated film
37 to be suppressed the side etching at the time of etching to
minimum.
Fourth Embodiment
[0147] As shown in FIG. 4, an electrode plate 40 according to the
fourth embodiment of this invention has a laminated film 45 which
has a lower side amorphous oxide layer 42, silver-based layer 43
and upper side oxide layer 44 sequentially laminated by sputtering
on a soda glass substrate 41 having an SiO.sub.2 (silicon oxide)
layer coated on the surface thereof and having an alkali barrier
function and which is formed into a preset pattern.
[0148] In the fourth embodiment, the film thickness of the lower
side amorphous oxide layer 42 is set to 50 nm, the film thickness
of the silver-based layer 43 is set to 150 nm, and the film
thickness of the upper side amorphous oxide layer 44 is set to 8.5
nm.
[0149] Therefore, the electrode plate 40 of the fourth embodiment
is a reflective type.
[0150] In this case, the lower side amorphous oxide layer 42 is
formed of a mixed material which contained cerium oxide as a main
material and additionally contained niobium oxide by 15 at % in
terms of the at % (atomic percentage) only of the metal atom which
does not include the oxygen atom. The upper side amorphous oxide
layer 44 is formed of a mixed oxide material containing indium
oxide and cerium oxide and the composition thereof contained indium
oxide 66.7 at % (atomic percentage) and cerium oxide 33.3 at %
(atomic percentage) in terms of the at % (atomic percentage) only
of the metal atom which does not include the oxygen atom. The
silver-based layer 43 is formed of a silver alloy having gold and
copper added to silver and the composition of the silver alloy
contained silver 98.5 at % (atomic percentage), gold 1.0 at %
(atomic percentage) and copper 0.5 at % (atomic percentage).
[0151] The electrode plate 40 according to the fourth embodiment is
formed by the following manufacturing process. That is, the soda
glass substrate 41 is subjected to the degreasing, cleaning and
drying process and then put into the sputtering chamber, and the
sputtering chamber is evacuated.
[0152] When a vacuum is drawn to the vacuum degree
5.times.10.sup.-4 Pa in the sputtering chamber, Ar (argon) gas and
O.sub.2 (oxygen) gas are introduced into the sputtering chamber to
adjust the gas pressure in the sputtering chamber to 0.35 Pa. At
this time, O.sub.2 (oxygen) gas in the introduced gas is adjusted
to 10% (for example, at the rate of 10 SCCM of the introduced
O.sub.2 gas with respect to introduced Ar gas of 100 SCCM) in terms
of the percentage of O.sub.2 gas in the introduced gas.
[0153] Next, after the above gas is introduced into the sputtering
chamber, a voltage is applied to a mixed oxide (cerium oxide and
niobium oxide) target with the above composition to form a lower
side amorphous oxide layer 42 on the substrate 41 by RF (high
frequency) sputtering.
[0154] When the step of forming the lower side amorphous oxide
layer 42 is completed, discharging and introduction of gas are
stopped and a vacuum is drawn to adjust the gas pressure to the
vacuum degree 5.times.10.sup.-4 Pa in the sputtering chamber.
[0155] Next, Ar gas is introduced into the sputtering chamber to
adjust the gas pressure to 0.4 Pa and a voltage is applied to a
silver alloy (silver, gold, copper) target with the above
composition to form a silver-based layer 43 by DC (direct current)
sputtering.
[0156] When the step of forming the silver-based layer 43 is
completed, discharging and introduction of gas are stopped and a
vacuum is drawn to adjust the gas pressure to the vacuum degree
5.times.10.sup.-4 Pa in the sputtering chamber.
[0157] Next, Ar (argon) gas and O.sub.2 (oxygen) gas are introduced
into the sputtering chamber to adjust the gas pressure in the
sputtering chamber to 0.35 Pa. At this time, the amount of O.sub.2
(oxygen) gas in the introduced gas is adjusted to 0.75% (for
example, at the rate of 0.75 SCCM of the introduced O.sub.2 gas
with respect to introduced Ar gas of 100 SCCM) in terms of the
percentage of O.sub.2 gas in the introduced gas.
[0158] Next, after the above gas is introduced into the sputtering
chamber, a voltage was applied to a mixed oxide (indium oxide and
cerium oxide) target with the above composition to form an upper
side amorphous oxide layer 44 by DC (direct current) sputtering and
thus a three-layered laminated film 45 is formed.
[0159] During the film formation, the substrate 41 is not heated
and film formation is continuously effected with the vacuum
condition kept.
[0160] According to the above-described materials, composition and
thicknesses, the light reflectance of the laminated film 45 is 88%
or more at the wavelength (400 to 700 nm) of the visible region and
is sufficiently large. Further, the area resistance of the
laminated film 45 is 0.28 .OMEGA./.quadrature. and the electrode
plate of low resistance can be realized.
[0161] Next, the manufacturing method for subjecting the laminated
film 45 obtained in the above manufacturing process to the
following photolithography process to form a preset pattern is
explained.
[0162] First, photosensitive resin (positive resist) is coated to a
film thickness 1 .mu.m on the laminated film 45 obtained in the
above manufacturing process by use of a spinner and then a dry
process is effected at 90.degree. C. for 20 minutes in an oven.
[0163] Next, after patterning exposure is effected on the
photosensitive resin by use of an exposure device using an exposure
photomask having a preset pattern, the development is effected by
use of an alkali developing solution (potassium hydroxide 10 weight
%). As a result, a portion of the photosensitive resin subjected to
the patterning exposure is dissolved and removed and a
photosensitive resin pattern is formed in a preset reflection film
portion.
[0164] After the development, a dry process is effected again at
90.degree. C. for 20 minutes in the oven.
[0165] Next, an etching solution containing a mixture of sulfuric
acid, nitric acid and acetic acid is used for etching the laminated
film and the etching process is effected by dipping the laminated
film in the etching solution at the liquid temperature 40.degree.
C. for approx. 30 seconds (that is, the portion of the laminated
film exposed from the photosensitive resin pattern was dissolved
and removed by etching). At the time of etching, the lower side
amorphous oxide layer 42 is not etched out and remained in the same
film form as it was formed.
[0166] After light is applied to the whole portion of the substrate
after etching, the photosensitive resin pattern is separated by use
of an alkali separating solution (potassium hydroxide 1 weight
%).
[0167] Next, the substrate is subjected to the drying process at
180.degree. C. for one hour to obtain the electrode plate 45
(reflection electrode) of a preset pattern.
[0168] The side etching to the laminated film 45 obtained in the
photolithography process is suppressed to minimum at the time of
etching and a gap (a distance between the adjacent electrodes)
between the electrode patterns formed by etching could be set to
such a small value as approx. 6 .mu.m.
[0169] According to the above manufacturing method, the width of
the electrode pattern can be enlarged by an amount by which the
amount of the side etching can be reduced and light can be
effectively reflected.
[0170] Further, the electrode plate 40 obtained in the fourth
embodiment is tested by use of the wiring tester to check the
electrical short-circuit between the electrode patterns, but the
electrical short circuit between the electrode patterns by the
lower side amorphous oxide layer 42 which is not etched and
remained is not observed and the electrode plate 40 with high
electrical stability can be realized.
[0171] Further, since the lower side amorphous oxide layer 42 and
upper side oxide layer 44 for holding the silver-based layer 43
therebetween are both formed of amorphous, occurrence of
aggregation and slight opaqueness caused by the movement of silver
at the interface with the silver-based layer, and a lowering in the
reflectance of the silver-based layer 43 due to the aggregation and
slight opaqueness can be suppressed.
Fifth Embodiment
[0172] Like the fourth embodiment, an electrode plate 40 according
to the fifth embodiment of this invention has a laminated film 45
which has a lower side amorphous oxide layer 42, silver-based layer
43 and upper side amorphous oxide layer 44 sequentially laminated
by sputtering on a soda glass substrate 41 having an SiO.sub.2
(silicon oxide) layer coated on the surface thereof and which is
formed into a preset pattern.
[0173] The schematic view of the electrode plate of the fifth
embodiment is the same as that of FIG. 4, but the thicknesses of
the layers are different and the film thickness of the lower side
amorphous oxide layer 42 was set to 50 nm, the film thickness of
the silver-based layer 43 is set to 150 nm and the film thickness
of the upper side amorphous oxide layer 44 is set to 3.5 nm.
[0174] Also, the electrode plate 40 of the fifth embodiment is a
reflective type.
[0175] The lower side amorphous oxide layer 42 is formed of a mixed
oxide material which contains cerium oxide as a main material and
additionally contained niobium oxide by 15 at % in terms of the at
% (atomic percentage) only of the metal atom which does not include
the oxygen atom. The upper side oxide layer 44 is formed of a mixed
oxide material containing indium oxide, cerium oxide, tin oxide and
titanium oxide and the composition thereof contains indium oxide 88
at % (atomic percentage), cerium oxide 8.5 at % (atomic
percentage),tin oxide 3.0 at % (atomic percentage) and titanium
oxide 0.5 at % in terms of the at % (atomic percentage) only of the
metal atom which does not include the oxygen atom. Further, the
silver-based layer 43 is formed of a silver alloy having gold and
copper added to silver and the composition of the silver alloy
contained silver 98.5 at % (atomic percentage), gold 1.0 at %
(atomic percentage) and copper 0.5 at % (atomic percentage).
[0176] The electrode plate 40 according to the fifth embodiment is
formed by the following manufacturing process. That is, the soda
glass substrate 41 is subjected to the degreasing, cleaning and
drying process and then put into the sputtering chamber.
[0177] The internal portion of the sputtering chamber used in the
fifth embodiment is divided into three continuous chambers. In
order to prevent contaminations occurring during the film formation
from giving an influence on the process in the adjacent chamber,
the chambers are arranged with a preset space from one another and
a shielding and exhaust measure is taken. After the soda glass
substrate 41 is put into the sputtering chamber, a vacuum is drawn
in the sputtering chamber, and Ar gas is introduced when the vacuum
degree reached 5.times.10.sup.-4 Pa and the gas pressure in the
sputtering chamber is adjusted to 0.4 Pa.
[0178] The soda glass substrate 41 put into the sputtering chamber
is carried by a carriage tray (not shown) and moved at a constant
speed in each chamber of the sputtering chamber. At this time, the
lower side amorphous oxide layer 42, silver-based layer 43 and
upper side amorphous oxide layer 44 are sequentially formed in the
respective chambers.
[0179] When the substrate 41 passes through the first chamber of
the sputtering chamber, a voltage is applied to a mixed oxide
(cerium oxide and niobium oxide) target having the above-described
composition to form a lower side amorphous oxide layer 42 by RF
(high frequency) sputtering. Likewise, when the substrate 41 passes
through the second chamber, a voltage is applied to a silver alloy
(silver, gold and copper) target with the above composition to form
a silver-based layer 43 by DC (direct current) sputtering. Next,
when the substrate 41 passes through the third chamber, a voltage
is applied to a mixed oxide (indium oxide and cerium oxide) target
having the above-described composition to form an upper side
amorphous oxide layer 44 by DC (direct current) sputtering. At the
time of formation of the oxide layer, O.sub.2 gas is introduced
into the first and third chambers in addition to Ar gas and the
rate of O.sub.2 gas introduced into the first chamber is 7% (the
rate of 7 SCCM of introduced O.sub.2 gas with respect to introduced
Ar gas of 100 SCCM) and the rate of O.sub.2 gas introduced into the
third chamber is 0.75% (the rate of 0.75 SCCM of introduced O.sub.2
gas with respect to introduced Ar gas of 100 SCCM).
[0180] During formation of the film on the substrate 41, the glass
substrate 41 is not heated and the substrate 41 is subjected to the
baking process at 180.degree. C. for one hour after the laminated
film is formed.
[0181] The three-layered laminated film 45 obtained in the fifth
embodiment is formed as a reflection film, the light reflectance
thereof is 90% or more and sufficiently large at the wavelength
(400 to 700 nm) of the visible region, and the area resistance is
as low as 0.27 .OMEGA./.quadrature..
[0182] Therefore, according to the electrode plate 40 having the
thin films with the above-described materials, the composition of
the materials and the thicknesses, the electrode plate with the
large reflectance and low resistance can be realized.
[0183] Further, since the lower side amorphous oxide layer 42 and
the upper side amorphous oxide layer 44 which hold the silver-based
layer 43 therebetween are both formed of amorphous, occurrence of
aggregation and slight opaqueness caused by the movement of silver
at the interface with the silver-based layer and a lowering in the
reflectance of the silver-based layer 43 due to the aggregation and
slight opaqueness can be suppressed.
[0184] Further, since the lower side amorphous oxide according to
the third, forth, fifth embodiment is insulation, patterning to the
lower side amorphous oxide is needless, which makes easy to form
patterns.
[0185] Therefore, according to the electrode plate with the above
materials, the composition of the materials and the thickness, a
transparent electrode plate with the large transmissivity or the
reflectance and low resistance can be realized.
[0186] Further, in this invention, since the insulated film can be
laminated being adjusted to attain an optical characteristic, the
conventional process for forming a insulated film called overcoat
is needless, which can make the manufacturing process to be
simple.
[0187] As described above, this invention has been explained with
reference to the embodiments, but this invention is not limited to
the above embodiments and, for example, this invention can be
variously modified without departing from the technical scope
thereof as follows.
[0188] (1) The lower side amorphous oxide layers in the third,
fourth, fifth and sixth embodiments were each formed of a mixed
oxide material which contained cerium oxide as a main material and
additionally contained niobium oxide by 15% in terms of the at %
(atomic percentage) only of the metal atom which did not include
the oxygen atom. Oxide added to cerium oxide is not limited to
niobium, but oxides of metals in the groups 3A, 4A, 5A of the
periodic table may be used. Particularly, it is preferable to add
one or more types of oxides selected from a group of ytrium oxide,
zirconium oxide, niobium oxide, hafnium oxide, tantalum oxide and
tungsten oxide.
[0189] The lower side amorphous oxide layer with the above
configurations has good adherence for the silver-based layer and
alkali barrier effect. Further, the lower side amorphous oxide
layer is enough stable not to be etched by etching solution used in
photolithography process and at the time of patterning, and remains
in the same film form as it was formed. As a result, if there is no
under-laid layer between a substrate and multi-layered conductive
film, migration of alkali metal to the silver-based layer is
prevented. Further, if the lower side amorphous oxide layer remains
in the film form, the lower side amorphous oxide layer does not
cause the electrical short circuit to the electrode patterns due to
having no conductivity.
[0190] With the above configuration, the same effect can be
attained.
[0191] (2) When the electrode plate according to this invention is
used for a liquid crystal or the like, the materials of the upper
side amorphous oxide layer 4, upper side amorphous oxide layer 24,
upper side amorphous oxide layer 44, amorphous oxide layer 35,
lower side amorphous oxide layer 2 and lower side amorphous oxide
layer 22 may be changed to the following material from the
viewpoint of the refractive index and conductivity.
[0192] That is, if it is desired to obtain oxide of the small
refractive index, for example, SiO.sub.2, MgO, Al.sub.2O.sub.3,
GeO.sub.2, Bi.sub.2O.sub.3 may be used and if it is desired to
obtain oxide of the large refractive index, for example, TiO.sub.2,
CeO.sub.2, ZrO.sub.2, HfO.sub.2, Nb.sub.2O.sub.5, Ta.sub.2O.sub.5
may be used. Further, as the conductive oxide material,
In.sub.2O.sub.3, SnO.sub.2, ZnO may be used, for example.
[0193] Therefore, an oxide material other than the above oxide
materials or a mixed oxide material selectively and mixedly
containing two or more types of the above oxide materials or the
like in which the number of oxygen elements added thereto is
adjusted may be used to form the amorphous oxide layer, upper side
amorphous oxide layer or lower side amorphous oxide layer.
[0194] If a mixed oxide material having In.sub.2O.sub.3 or ZnO used
as the substrate material is used, the etching process can be
easily effected.
[0195] Further, the precision of the configuration of the electrode
pattern formed on the electrode plate and the reliability of the
electrode according to this invention can be further enhanced by
adding a small amount of oxide material such as ZnO or MgO which is
easily dissolved into acid to the above mixed oxide material so as
to set the oxidation-reduction potential of the mixed oxide
material closer to that of the silver-based layer.
[0196] Further, a layer with the large refractive index may be
inserted into the central portion in the thickness direction of the
silver-based layer used for the electrode plate according to this
invention from the viewpoint of the refractive index. In the case
of a transmission type conductive film, a conductive film with the
smaller reflectance can be obtained by inserting a layer with the
large refractive index between the silver-based layers. At this
time, the transmissivity may be improved in some cases.
[0197] (3) In all of the above embodiments, the transparent
substrate was used as the substrate used for the electrode plate
for display device according to this invention. However, the
substrate is not necessary transparent and may be a substrate which
is colored in white, black or other color according to the
application of the display device.
[0198] The substrate itself may be a substrate on which an electric
circuit is formed, a silicon wafer substrate on which a solar
battery is formed, or a heat-resistant organic film or a substrate
on which semiconductor elements of amorphous silicon, polysilicon
or MIM (diode elements) are formed.
[0199] Further, it is possible to directly or indirectly form a
polarization element, diffraction grating, hologram, light
scattering film, .lambda./4 wavelength plate, phase difference
film, micro-lens, color filter or the like on the substrate.
[0200] (4) The protection layer in the above embodiments is formed
of oxide which is highly resistant to chemical and has a high
insulating property from the viewpoint of reliability (durability).
However, nitride, organic resin, fluororesin, Teflon resin, silicon
resin or the like may be used other than the above oxide material,
or a coating film having a transparent pigment mixed in the above
materials may be used. Further, a reflection preventing film or
water repellent layer can be formed on the protection layer from
the viewpoint of reliability (durability).
[0201] In a case where the electrode plate of this invention is
used for solar battery (in this case, a semiconductor element of
amorphous silicon, for example, is formed on the substrate), the
protection layer may be formed sufficiently thick to attain high
reliability (high durability).
[0202] Further, the protection layer may be formed by use of the
sol-gel method which is used for means for forming a layer which is
generally called an "overcoat" on the liquid crystal substrate.
[0203] When the protection layer is required to have a large
dielectric factor for driving the crystal such as TFT,
ferroelectric crystal or antiferroelectric crystal, the protection
layer may be formed of a material with large dielectric factor.
[0204] (5) The silver-based layer included in the electrode plate
according to the first, second, third, forth and fifth embodiment
forms a preferable reflection electrode when the film thickness the
silver-based layer is set to approx. 100 to 200 nm or more and
forms a preferable transparent electrode when the film thickness
thereof is set in a range of approx. 7 to 25 nm. However, the film
thickness thereof is not limited in the above ranges. If the
silver-based layer forms a semi-reflection electrode or
semi-transparent electrode when the film thickness thereof is set
to approx. 5 to 100 nm. The each of the transparent component and
the reflection component has the same effect of the present
invention.
[0205] Note that, generally speaking, the electrode plate is a
preferable reflective electrode plate when the reflectance of the
electrode plate is more than 70% and is a preferable transparent
electrode when the transmissivity of the electrode plate is more
than 88% at the wavelength (400 to 700 nm) of the visible
region.
[0206] As described above, according to this invention, an
electrode plate having a transmission type or reflective type
conductive film and having an excellent optical characteristic
(transmissivity, reflectance), low electrical connection
resistance, good patterning configuration, and high stability can
be realized.
* * * * *