U.S. patent application number 16/463459 was filed with the patent office on 2019-11-28 for film formation method and method of manufacturing display device using the same.
The applicant listed for this patent is Sharp Kabushiki Kaisha. Invention is credited to Takeshi HIRASE.
Application Number | 20190363308 16/463459 |
Document ID | / |
Family ID | 65900941 |
Filed Date | 2019-11-28 |
![](/patent/app/20190363308/US20190363308A1-20191128-D00000.png)
![](/patent/app/20190363308/US20190363308A1-20191128-D00001.png)
![](/patent/app/20190363308/US20190363308A1-20191128-D00002.png)
![](/patent/app/20190363308/US20190363308A1-20191128-D00003.png)
![](/patent/app/20190363308/US20190363308A1-20191128-D00004.png)
![](/patent/app/20190363308/US20190363308A1-20191128-D00005.png)
![](/patent/app/20190363308/US20190363308A1-20191128-D00006.png)
United States Patent
Application |
20190363308 |
Kind Code |
A1 |
HIRASE; Takeshi |
November 28, 2019 |
FILM FORMATION METHOD AND METHOD OF MANUFACTURING DISPLAY DEVICE
USING THE SAME
Abstract
A film formation method of introducing, into a film formation
chamber, a vaporized material obtained by vaporizing a liquid-form
organic material in a vaporizing chamber and forming a vapor
deposition film composed of the vaporized material on a surface of
a film formed substrate placed within the film formation chamber.
The method includes: holding an internal temperature of the
vaporizing chamber at a lower temperature than a reaction
temperature at which the organic material polymerizes; holding an
internal pressure of the vaporizing chamber at a saturated vapor
pressure of the organic material; setting an internal temperature
of the film formation chamber to the same temperature as the
internal temperature of the vaporizing chamber; and forming the
film in a state where the film formed substrate is held at a
temperature lower than the internal temperature of the film
formation chamber.
Inventors: |
HIRASE; Takeshi; (Sakai
City, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sharp Kabushiki Kaisha |
Sakai City, Osaka |
|
JP |
|
|
Family ID: |
65900941 |
Appl. No.: |
16/463459 |
Filed: |
September 28, 2017 |
PCT Filed: |
September 28, 2017 |
PCT NO: |
PCT/JP2017/035187 |
371 Date: |
May 23, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 14/24 20130101;
H01L 51/0097 20130101; H01L 2251/556 20130101; H01L 51/5256
20130101; B05D 1/60 20130101; H05B 33/10 20130101; H01L 51/5253
20130101; C23C 14/5806 20130101; G09F 9/30 20130101; H05B 33/04
20130101; H01L 51/50 20130101; H01L 51/56 20130101; H01L 2251/5338
20130101; C23C 14/12 20130101; H01L 27/3244 20130101; C23C 14/584
20130101; H01L 27/32 20130101 |
International
Class: |
H01L 51/56 20060101
H01L051/56; H01L 27/32 20060101 H01L027/32; H01L 51/00 20060101
H01L051/00; H01L 51/52 20060101 H01L051/52; B05D 1/00 20060101
B05D001/00 |
Claims
1. A film formation method of introducing, into a film formation
chamber, a vaporized material obtained by vaporizing a liquid-form
organic material in a vaporizing chamber and forming a vapor
deposition film composed of the vaporized material on a surface of
a film formed substrate placed within the film formation chamber,
the method comprising: holding an internal temperature of the
vaporizing chamber at a lower temperature than a reaction
temperature at which the organic material polymerizes; holding an
internal pressure of the vaporizing chamber at a saturated vapor
pressure of the organic material; setting an internal temperature
of the film formation chamber to the same temperature as the
internal temperature of the vaporizing chamber; and forming the
film in a state where the film formed substrate is held at a
temperature lower than the internal temperature of the film
formation chamber.
2. The film formation method according to claim 1, wherein the
reaction temperature is determined through differential scanning
calorimetry on the organic material.
3. A method of manufacturing a display device, the method
comprising: a light emitting element formation step of forming a
light emitting element on a base substrate; and a sealing film
formation step of forming a sealing film covering the light
emitting element, wherein the sealing film formation step includes
an organic film formation step of forming an organic film covering
the light emitting element, the organic film being formed by
forming a vapor deposition film through the film formation method
according to claim 1.
4. The method of manufacturing a display device according to claim
3, wherein the sealing film formation step includes: a first
inorganic layer formation step of forming a first inorganic layer
covering the light emitting element, before the organic film
formation step; forming the organic film covering the first
inorganic layer in the organic film formation step; a second
inorganic layer formation step of forming a second inorganic layer,
overlapping with the first inorganic layer, on the organic film,
after the organic film formation step; an organic layer formation
step of forming an organic layer by removing the organic film
exposed from the second inorganic layer through ashing; and a third
inorganic layer formation step of forming a third inorganic layer
covering a perimeter edge surface of the organic layer and the
second inorganic layer.
5. The method of manufacturing a display device according to claim
4, wherein the sealing film formation step includes a
polymerization step of forming the organic film by irradiating the
vapor deposition film with ultraviolet light and causing the vapor
deposition film to polymerize, the polymerization step being
carried out between the organic film formation step and the second
inorganic layer formation step.
6. The method of manufacturing a display device according to claim
4, wherein in the organic layer formation step, the organic film is
removed using the second inorganic layer as a mask.
7. The method of manufacturing a display device according to claim
3, wherein the light emitting element is an organic EL element.
Description
TECHNICAL FIELD
[0001] The disclosure relates to a film formation method and a
method of manufacturing a display device using the same.
BACKGROUND ART
[0002] In recent years, organic EL display devices, which use
organic electroluminescence (EL) elements and are of the
self-luminous type, have attracted attention as display devices
that can replace liquid crystal display devices.
[0003] For example, PTL 1 discloses a method of manufacturing an
organic EL element, in which an organic light emitting element is
formed by ejecting a vaporized material composed of an organic
luminescent material toward a substrate from a nozzle located at a
distance of 15 mm or less from the substrate.
CITATION LIST
Patent Literature
[0004] PTL 1: JP 2008-287996 A
SUMMARY
Technical Problem
[0005] However, with a vacuum vapor deposition method such as that
disclosed in the above-described PTL 1, the film formed substrate
and the nozzle are close to each other, and it is therefore
difficult to ensure a uniform distribution in the flow of the
vaporized material from the nozzle toward the film formed
substrate. It is thus difficult to form a vapor deposition film
having a uniform film thickness, particularly when depositing a
material having a low saturated vapor pressure such as an acrylic
resin.
[0006] Having been conceived in light of this point, an object of
the disclosure is to form a vapor deposition film having a uniform
film thickness.
Solution to Problem
[0007] To achieve the above-described object, a film formation
method according to the disclosure is a film formation method of
introducing, into a film formation chamber, a vaporized material
obtained by vaporizing a liquid-form organic material in a
vaporizing chamber and forming a vapor deposition film composed of
the vaporized material on a surface of a film formed substrate
placed within the film formation chamber. The method includes:
holding an internal temperature of the vaporizing chamber at a
lower temperature than a reaction temperature at which the organic
material polymerizes; holding an internal pressure of the
vaporizing chamber at a saturated vapor pressure of the organic
material; setting an internal temperature of the film formation
chamber to the same temperature as the internal temperature of the
vaporizing chamber; and forming the film in a state where the film
formed substrate is held at a temperature lower than the internal
temperature of the film formation chamber.
Advantageous Effects of Disclosure
[0008] According to the disclosure, the internal temperature of the
vaporizing chamber is held at a lower temperature than the reaction
temperature at which the organic material polymerizes; the internal
pressure of the vaporizing chamber is held at the saturated vapor
pressure of the organic material; the internal temperature of the
film formation chamber is set to the same temperature as the
internal temperature of the vaporizing chamber; and the film is
formed in a state where the film formed substrate is held at a
temperature lower than the internal temperature of the film
formation chamber. Accordingly, the vapor deposition film can be
formed at a uniform thickness.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a schematic diagram illustrating an overview of a
film formation apparatus used in a film formation method according
to a first embodiment of the disclosure.
[0010] FIG. 2 is a schematic diagram primarily illustrating a
vaporizing chamber constituting the film formation apparatus used
in the film formation method according to the first embodiment of
the disclosure.
[0011] FIG. 3 is a graph showing a vapor pressure curve of an
organic material used in the film formation method according to the
first embodiment of the disclosure.
[0012] FIG. 4 is a cross-sectional view of an organic EL display
device according to a second embodiment of the disclosure,
schematically illustrating the configuration of the device.
[0013] FIG. 5 is a cross-sectional view of the organic EL display
device according to the second embodiment of the disclosure,
illustrating the internal configuration of the device.
[0014] FIG. 6 is a cross-sectional view of an organic EL layer
included in an organic EL display device according to the first
embodiment of the disclosure.
[0015] FIG. 7 is a cross-sectional view illustrating a method of
manufacturing the organic EL display device according to the first
embodiment of the disclosure.
[0016] FIG. 8 is a cross-sectional view illustrating the method of
manufacturing the organic EL display device according to the first
embodiment of the disclosure, continuing from FIG. 7.
[0017] FIG. 9 is a cross-sectional view illustrating the method of
manufacturing the organic EL display device according to the first
embodiment of the disclosure, continuing from FIG. 8.
[0018] FIG. 10 is a cross-sectional view illustrating the method of
manufacturing the organic EL display device according to the first
embodiment of the disclosure, continuing from FIG. 9.
[0019] FIG. 11 is a cross-sectional view illustrating the method of
manufacturing the organic EL display device according to the first
embodiment of the disclosure, continuing from FIG. 10.
DESCRIPTION OF EMBODIMENTS
[0020] Embodiments of the disclosure will be described in detail
below with reference to the drawings. The disclosure is not limited
to the embodiments described below.
First Embodiment
[0021] FIGS. 1 to 3 illustrate an embodiment of a film formation
method according to the disclosure. Here, FIG. 1 is a schematic
diagram illustrating an overview of a film formation apparatus 100
used in the film formation method according to the present
embodiment. FIG. 2 is a schematic diagram primarily illustrating a
vaporizing chamber 50 constituting the film formation apparatus
100. FIG. 3 is a graph showing a vapor pressure curve of an organic
material M used in the film formation method according to the
present embodiment.
[0022] As illustrated in FIGS. 1 and 2, the film formation
apparatus 100 includes the vaporizing chamber 50, a film formation
chamber 60, and a connection pipe 55 that connects the vaporizing
chamber 50 with the film formation chamber 60.
[0023] As illustrated in FIGS. 1 and 2, a vapor deposition source
51 is provided within the vaporizing chamber 50. The organic
material M is supplied to the vapor deposition source 51 in a
liquid state via a material pipe 45 from a material tank 40. The
organic material M is vaporized by the vapor deposition source 51,
and a vaporized material G produced by vaporizing the organic
material M is discharged to the connection pipe 55. Here, as
illustrated in FIG. 2, an inert gas such as helium or nitrogen is
introduced to valves provided in the channels formed by the
material pipe 45 and the connection pipe 55 disposed within the
vaporizing chamber 50. The valves replace the atmosphere within
those channels with the inert gas. As illustrated in FIG. 2, the
inert gas such as helium or nitrogen is introduced while
controlling the flow rate of that gas using a mass flow controller
52 provided in the channel formed by the connection pipe 55. As a
result, the atmosphere in the channel formed by the connection pipe
55 is replaced with the inert gas. The vaporizing chamber 50 is
configured to hold an internal temperature and an internal pressure
within a predetermined range.
[0024] As illustrated in FIGS. 1 and 2, the film formation chamber
60 contains a film formed substrate S and is configured to form a
vapor deposition film F by depositing the vaporized material G
supplied from the connection pipe 55 onto a surface of the film
formed substrate S. A stage is provided within the film formation
chamber 60. The film formed substrate S is placed on the stage, and
the temperature of the film formed substrate S placed on the stage
is thus held within the predetermined range. The film formation
chamber 60 is also configured to hold an internal temperature and
an internal pressure within a predetermined range.
[0025] The film formation apparatus 100 is configured so that when
forming the vapor deposition film F on the surface of the film
formed substrate S, the internal temperature of the vaporizing
chamber 50 is held lower than the reaction temperature of the
organic material M, the internal pressure of the vaporizing chamber
50 is held at the saturated vapor pressure of the organic material
M, the internal temperatures of the film formation chamber 60 and
the connection pipe 55 are set to be the same as the internal
temperature of the vaporizing chamber 50, and the film formed
substrate S is held lower than the internal temperature of the film
formation chamber.
[0026] A film formation method using the film formation apparatus
100 according to the present embodiment will be described next.
[0027] First, the organic material M is subjected to differential
scanning calorimetry (DSC) to consider the internal temperature of
the vaporizing chamber 50, the film formation chamber 60, and the
connection pipe 55; and the reaction temperature of the organic
material M is measured. An acrylic monomer, a polyurea monomer, a
polyamide monomer, a polysiloxane monomer, a polyurethane monomer,
and the like can be given as examples of the organic material M,
for example. Note that the internal temperature of the vaporizing
chamber 50, the film formation chamber 60, and the connection pipe
55 is set to be lower than the reaction temperature at which the
organic material M polymerizes. Specifically, if the organic
material M is an acrylic monomer having a molecular weight of 1000,
the reaction temperature is approximately 70.degree. C.
Accordingly, the internal temperature of the vaporizing chamber 50,
the film formation chamber 60, and the connection pipe 55 is set to
be lower than approximately 70.degree. C., namely, to approximately
60.degree. C.
[0028] Next, after a vapor pressure curve of the organic material M
(see FIG. 3) has been found, the temperature and pressure at two
points, for example, are read from the vapor pressure curve.
Specifically, at 40.degree. C. (T.sub.1=313 K), for example, the
pressure is 3 Pa (P.sub.1=3 Pa), and at 140.degree. C. (T.sub.2=413
K), the pressure is 500 Pa (P.sub.2=500 Pa).
[0029] Furthermore, a latent heat of vaporization L is calculated
by substituting the values of the above-described temperatures,
pressures, and R (gas constant=8.31441 J/(molK)) into the formula
log.sub.10 (P.sub.2/P.sub.1)=-L/2.303R(1/T.sub.2-1/T.sub.1). Here,
the specific latent heat of vaporization L is 54.965 kJ/mol.
[0030] Next, assuming that .tau..sub.0=1.0.times.10.sup.-13, an
average adsorption time ti is calculated by substituting the values
of L, R, and T in the formula .tau.=.tau..sub.0e.sup.L/RT. Here,
the specific average adsorption time .tau. is 2.23.times.10.sup.-2
s at -20.degree. C. (253 K), 1.49.times.10.sup.-4 s at 40.degree.
C. (313 K), 4.19.times.10.sup.-5 s at 60.degree. C. (333 K),
1.36.times.10.sup.-5 s at 80.degree. C. (353 K), and
8.95.times.10.sup.-7 s at 140.degree. C. (413 K).
[0031] Next, assuming that .eta.=1000 (the molecular weight of the
acrylic monomer), a molecular velocity v is calculated by
substituting R and T into the formula
v=(3RT/.eta..times.10.sup.-3).sup.1/2. Here, the specific molecular
velocity v is 88 m/s when the temperature is 40.degree. C. (313 K),
91 m/s when the temperature is 60.degree. C. (333 K), and 94 m/s
when the temperature is 80.degree. C. (353 K). Calculating a time t
for a flight of 2.5 cm from the exit end of the connection pipe 55
results in 2.83.times.10.sup.-4 s at 40.degree. C. (313 K),
2.74.times.10.sup.-4 s at 60.degree. C. (333 K), and
2.66.times.10.sup.-4 s at 80.degree. C. (353 K).
[0032] The average adsorption time .tau., velocity v, and flight
time t of the acrylic monomer molecules can be calculated in this
manner, which makes it possible to determine the acceptability of
the film formation (deposition) process conditions.
[0033] The specific film formation method is as follows. First, the
film formed substrate S is placed within the film formation chamber
60. The internal temperature of the vaporizing chamber 50, the film
formation chamber 60, and the connection pipe 55 are held at
60.degree. C. The internal pressure of the vaporizing chamber 50 is
held at the saturated vapor pressure of the organic material M at
60.degree. C., which is 10 Pa. Furthermore, the temperature of the
film formed substrate S is held at -20.degree. C. The surface
temperature of the film formed substrate S is therefore lower than
the internal temperature of the film formation chamber 60, and thus
the vapor pressure of the vaporized material G drops at the surface
of the film formed substrate S. As a result, it becomes easy to
deposit particles of the vaporized material G onto the surface of
the film formed substrate S. The vapor deposition film F, which is
composed of the vaporized material G, can therefore be formed on
the surface of the film formed substrate S at a uniform thickness.
By then irradiating the formed vapor deposition film F with
ultraviolet light or baking the vapor deposition film F, the vapor
deposition film F can be polymerized, and an organic film having a
uniform thickness can be formed (a polymerization process). Here,
the speed at which the vapor deposition film F is formed is
determined by the internal temperature of the vaporizing chamber
50, the temperature of the film formed substrate S, and the
vaporized surface area of the organic material M in the vapor
deposition source 51. Accordingly, the internal temperature of the
vaporizing chamber 50 is set to a desired temperature, and once the
saturated vapor pressure is attained, the organic material is
deposited onto a dummy substrate to find the film formation speed
before forming the film on a substrate that will be used as a
product. According to the method of the present embodiment, the
vaporized material G of the organic material M is introduced into
the film formation chamber 60, and the vaporized material G of the
organic material M is deposited onto the film formed substrate S to
form the film, once the vaporizing chamber 50 has reached a state
of vapor-liquid equilibrium. As such, the film can be formed at a
highly uniform speed. Accordingly, the film formation time can be
found from the desired thickness of the vapor deposition film F, on
the basis of the film formation speed found using the dummy
substrate. That film formation time can then be used as the process
conditions for forming a film on a substrate to be used as a
product.
[0034] As described thus far, according to the film formation
method of the present embodiment, the internal temperature of the
vaporizing chamber 50 is held lower than the reaction temperature
of the organic material M, the internal pressure of the vaporizing
chamber 50 is held at the saturated vapor pressure of the organic
material M, the internal temperature of the film formation chamber
60 is set to be the same as the internal temperature of the
vaporizing chamber 50, and the film formed substrate S is held at a
temperature lower than the internal temperature of the film
formation chamber 60. Accordingly, the vapor pressure of the
vaporized material G drops at the surface of the film formed
substrate S. Here, unlike a typical vacuum vapor deposition method
that uses a carrier gas to deposit a material having a relatively
high saturated vapor pressure, it is conceivable that the molecules
of the vaporized material G obtained by vaporizing the organic
material M, which has a relatively low saturated vapor pressure,
will move isotropically in a non-flowing atmosphere. As a result,
it becomes easy to deposit particles of the vaporized material G
onto the surface of the film formed substrate S, even with the
organic material M having a low saturated vapor pressure. The vapor
deposition film F, which is composed of the vaporized material G,
can therefore be formed on the surface of the film formed substrate
S at a uniform thickness. Furthermore, an organic film having a
uniform thickness can be formed by polymerizing the vapor
deposition film F that has been formed at a uniform thickness.
Second Embodiment
[0035] FIGS. 4 to 11 illustrate an embodiment of a method of
manufacturing a display device according to the disclosure. In the
present embodiment, an organic EL display device including an
organic EL element will be described as an example of a display
device including a light emitting element. Here, FIG. 4 is a
cross-sectional view of an organic EL display device 30 according
to the present embodiment, schematically illustrating the
configuration of the device. FIG. 5 is a cross-sectional view of
the organic EL display device 30, illustrating the internal
configuration of the device. FIG. 6 is a cross-sectional view of an
organic EL layer 16 included in the organic EL display device
30.
[0036] As illustrated in FIGS. 4 and 5, the organic EL display
device 30 includes a base substrate 10, an organic EL element 18,
and a sealing film 23. The organic EL element 18 is provided, as a
light emitting element, upon the base substrate 10 with a base
coating film 11 interposed therebetween, and the sealing film 23 is
provided covering the organic EL element 18. Here, in the organic
EL display device 30, a display region D in which images are
displayed is provided as a rectangular shape by the organic EL
element 18, and in the display region D, a plurality of pixels are
arranged in a matrix. Each of the pixels includes a subpixel for
displaying a red tone, a subpixel for displaying a green tone, and
a subpixel for displaying a blue tone, for example. These subpixels
are disposed adjacent to one another. Note that in the organic EL
display device 30, a frame-shaped frame region is defined in the
periphery of the rectangular display region D.
[0037] The base substrate 10 is a flexible plastic substrate formed
from a polyimide resin or the like, for example.
[0038] The base coating film 11 is an inorganic insulating film
such as a silicon oxide film, a silicon nitride film, or a silicon
oxynitride film, for example.
[0039] As illustrated in FIG. 5, the organic EL element 18 includes
a plurality of TFTs 12, a flattening film 13, a plurality of first
electrodes 14, an edge cover 15, a plurality of organic EL layers
16, and a second electrode 17, provided in that order on the base
coating film 11.
[0040] The TFT 12 is a switching element provided for each of the
subpixels in the display region D. Here, the TFTs 12 each include,
for example, semiconductor layer, a gate insulating film, a gate
electrode, an interlayer insulating film, and source and drain
electrodes. The semiconductor layer is provided on the base coating
film 11 in an island shape. The gate insulating film is provided
covering the semiconductor layer. The gate electrode is provided on
the gate insulating film so as to overlap with a part of the
semiconductor layer. The interlayer insulating film is provided
covering the gate electrode. The source and drain electrodes are
arranged separated from each other. In the present embodiment, the
top-gate type is described as an example of the TFT 12, but the TFT
12 may be of the bottom-gate type.
[0041] As illustrated in FIG. 5, the flattening film 13 is provided
to cover the TFTs 12 except for a portion of each of the drain
electrodes. Here, the flattening film 13 is composed of a colorless
transparent organic resin material such as an acrylic resin, for
example.
[0042] As illustrated in FIG. 5, the plurality of first electrodes
14 are provided in a matrix over the flattening film 13,
corresponding to a plurality of subpixels. Here, as illustrated in
FIG. 5, the first electrodes 14 are connected to the respective
drain electrodes of the TFTs 12 via respective contact holes formed
in the flattening film 13. The first electrode 14 functions to
inject holes into the organic EL layer 16. It is more preferable
that the first electrodes 14 include a material having a large work
function to improve the efficiency of hole injection into the
organic EL layer 16. Examples of materials that may be included in
the first electrode 14 include metal materials, such as silver
(Ag), aluminum (Al), vanadium (V), cobalt (Co), nickel (Ni),
tungsten (W), gold (Au), calcium (Ca), titanium (Ti), yttrium (Y),
sodium (Na), ruthenium (Ru), manganese (Mn), indium (In), magnesium
(Mg), lithium (Li), ytterbium (Yb), and lithium fluoride (LiF).
Further examples of materials that may be included in the first
electrode 14 include alloys, the examples of which include
magnesium (Mg)-copper (Cu), magnesium (Mg)-silver (Ag), sodium
(Na)-potassium (K), astatine (At)-astatine oxide (AtO.sub.2),
lithium (Li)-aluminum (Al), lithium (Li)-calcium (Ca)-aluminum
(Al), and lithium fluoride (LiF)-calcium (Ca)-aluminum (Al).
Further examples of materials that may be included in the first
electrode 14 include electrically conductive oxides, the examples
of which include tin oxide (SnO), zinc oxide (ZnO), indium tin
oxide (ITO), and indium zinc oxide (IZO). The first electrode 14
may include a stack of two or more layers of any of the
above-mentioned materials. Examples of materials having a large
work function include indium tin oxide (ITO) and indium zinc oxide
(IZO).
[0043] As illustrated in FIG. 5, the edge cover 15 is provided in a
lattice pattern so as to cover the peripheral portions of each of
the first electrodes 14. Examples of materials that may constitute
the edge cover 15 include inorganic films such as silicon oxide
(SiO.sub.2), silicon nitride (SiNx (x is a positive number)) such
as trisilicon tetranitride (Si.sub.3N.sub.4), and silicon
oxynitride (SiON), or organic films such as polyimide resins,
acrylic resins, polysiloxane resins, and novolac resins.
[0044] As illustrated in FIG. 5, the plurality of organic EL layers
16 are arranged in a matrix on the respective first electrodes 14,
and correspond to the respective subpixels. Here, as illustrated in
FIG. 6, the organic EL layers 16 each include a hole injection
layer 1, a hole transport layer 2, a light-emitting layer 3, an
electron transport layer 4, and an electron injection layer 5,
which are arranged in that order over the first electrode 14.
[0045] The hole injection layer 1 is also referred to as an anode
buffer layer, and functions to reduce the energy level difference
between the first electrode 14 and the organic EL layer 16 so as to
improve the efficiency of hole injection into the organic EL layer
16 from the first electrode 14. Examples of materials that may
constitute the hole injection layer 1 include triazole derivatives,
oxadiazole derivatives, imidazole derivatives, polyarylalkane
derivatives, pyrazoline derivatives, phenylenediamine derivatives,
oxazole derivatives, styrylanthracene derivatives, fluorenone
derivatives, hydrazone derivatives, and stilbene derivatives.
[0046] The hole transport layer 2 functions to improve the
efficiency of hole transport from the first electrode 14 to the
organic EL layer 16. Examples of materials that may constitute the
hole transport layer 2 include porphyrin derivatives, aromatic
tertiary amine compounds, styrylamine derivatives,
polyvinylcarbazole, poly-p-phenylenevinylene, polysilane, triazole
derivatives, oxadiazole derivatives, imidazole derivatives,
polyarylalkane derivatives, pyrazoline derivatives, pyrazolone
derivatives, phenylenediamine derivatives, arylamine derivatives,
amine-substituted chalcone derivatives, oxazole derivatives,
styrylanthracene derivatives, fluorenone derivatives, hydrazone
derivatives, stilbene derivatives, hydrogenated amorphous silicon,
hydrogenated amorphous silicon carbide, zinc sulfide, and zinc
selenide.
[0047] The light-emitting layer 3 is a region where, when a voltage
is applied via the first electrode 14 and the second electrode 17,
holes and electrons are injected from the first electrode 14 and
the second electrode 17, respectively, and the holes and the
electrons recombine. Here, the light-emitting layer 3 is formed
from a material having a high light emitting efficiency. Examples
of materials that may constitute the light-emitting layer 3 include
metal oxinoid compounds (8-hydroxyquinoline metal complexes),
naphthalene derivatives, anthracene derivatives, diphenyl ethylene
derivatives, vinyl acetone derivatives, triphenylamine derivatives,
butadiene derivatives, coumarin derivatives, benzoxazole
derivatives, oxadiazole derivatives, oxazole derivatives,
benzimidazole derivatives, thiadiazole derivatives, benzothiazole
derivatives, styryl derivatives, styrylamine deriatives,
bisstyrylbenzene derivatives, trisstyrylbenzene derivatives,
perylene derivatives, perinone derivatives, aminopyrene
derivatives, pyridine derivatives, rhodamine derivatives, aquidine
derivatives, phenoxazone, quinacridone derivatives, rubrene,
poly-p-phenylenevinylene, and polysilane.
[0048] The electron transport layer 4 functions to facilitate the
efficient migration of the electrons to the light-emitting layer 3.
Examples of materials that may constitute the electron transport
layer 4 include organic compounds, the examples of which include
oxadiazole derivatives, triazole derivatives, benzoquinone
derivatives, naphthoquinone derivatives, anthraquinone derivatives,
tetracyanoanthraquinodimethane derivatives, diphenoquinone
derivatives, fluorenone derivatives, silole derivatives, and metal
oxinoid compounds.
[0049] The electron injection layer 5 functions to reduce the
energy level difference between the second electrode 17 and the
organic EL layer 16, to improve the efficiency of electron
injection into the organic EL layer 16 from the second electrode
17. Because of this function, the driving voltage for the organic
EL element 18 can be reduced. The electron injection layer 5 is
also referred to as a cathode buffer layer. Examples of materials
that may constitute the electron injection layer 5 include
inorganic alkaline compounds, such as lithium fluoride (LiF),
magnesium fluoride (MgF.sub.2), calcium fluoride (CaF.sub.2),
strontium fluoride (SrF.sub.2), and barium fluoride (BaF.sub.2);
aluminum oxide (Al.sub.2O.sub.3); and strontium oxide (SrO).
[0050] As illustrated in FIG. 5, the second electrode 17 is
provided so as to cover the organic EL layers 16 and the edge cover
15, and is provided in common for the plurality of subpixels. The
second electrode 17 functions to inject electrons into the organic
EL layer 16. It is more preferable that the second electrode 17
includes a material having a small work function to improve the
efficiency of electron injection into the organic EL layer 16.
Examples of materials that may constitute the second electrode 17
include silver (Ag), aluminum (Al), vanadium (V), cobalt (Co),
nickel (Ni), tungsten (W), gold (Au), calcium (Ca), titanium (Ti),
yttrium (Y), sodium (Na), ruthenium (Ru), manganese (Mn), indium
(In), magnesium (Mg), lithium (Li), ytterbium (Yb), and lithium
fluoride (LiF). Further examples of materials that may be included
in the second electrode 17 include alloys, the examples of which
include magnesium (Mg)-copper (Cu), magnesium (Mg)-silver (Ag),
sodium (Na)-potassium (K), astatine (At)-astatine oxide
(AtO.sub.2), lithium (Li)-aluminum (Al), lithium (Li)-calcium
(Ca)-aluminum (Al), and lithium fluoride (LiF)-calcium
(Ca)-aluminum (Al). Further examples of materials that may be
included in the second electrode 17 include electrically conductive
oxides, the examples of which include tin oxide (SnO), zinc oxide
(ZnO), indium tin oxide (ITO), and indium zinc oxide (IZO). The
second electrode 17 may include a stack of two or more layers of
any of the above-mentioned materials. Examples of materials having
a small work function include magnesium (Mg), lithium (Li), lithium
fluoride (LiF), magnesium (Mg)-copper (Cu), magnesium (Mg)-silver
(Ag), sodium (Na)-potassium (K), lithium (Li)-aluminum (Al),
lithium (Li)-calcium (Ca)-aluminum (Al), and lithium fluoride
(LiF)-calcium (Ca)-aluminum (Al).
[0051] As illustrated in FIG. 4, the sealing film 23 includes a
first inorganic layer 19, an organic layer 20, a second inorganic
layer 21, and a third inorganic layer 22. The first inorganic layer
19 is provided so as to cover the organic EL element 18. The
organic layer 20 and the second inorganic layer 21 are layered in
that order on the first inorganic layer 19. The third inorganic
layer 22 is provided so as to cover a perimeter edge surface of the
organic layer 20 and the second inorganic layer 21.
[0052] The first inorganic layer 19, the second inorganic layer 21,
and the third inorganic layer 22 are composed of an inorganic
insulating film such as a silicon nitride film, a silicon oxide
film, a silicon oxynitride film, or the like, for example.
Preferably, the second inorganic layer 21 is composed of a silicon
nitride film, which has high barrier properties, for example.
[0053] As illustrated in FIG. 4, the perimeter edge surfaces of the
first inorganic layer 19 are located further outward than the
perimeter edge surfaces of the organic layer 20 and the second
inorganic layer 21.
[0054] The organic layer 20 is composed of an organic resin
material such as an acrylate, polyurea, parylene, polyimide,
polyamide, or the like, for example. As illustrated in FIG. 4, the
locations of the perimeter edge surfaces of the organic layer 20
match the locations of the perimeter edge surfaces of the second
inorganic layer 21, as a result of the manufacturing method
described later.
[0055] The above-described organic EL display device 30 is
flexible. In each of the subpixels, the light-emitting layer 3 of
the organic EL layer 16 is caused, via the TFT 12, to emit light as
appropriate so as to display images.
[0056] A method of manufacturing the organic EL display device 30
according to the present embodiment will be described next using
FIGS. 7 to 11. FIGS. 7 to 11 are cross-sectional views illustrating
the method of manufacturing the organic EL display device 30. The
method of manufacturing the organic EL display device 30 according
to the present embodiment includes forming an organic EL element
and forming a sealing film. Forming the sealing film includes
forming a first inorganic layer, forming an organic film, forming a
second inorganic layer, forming an organic layer, and forming a
third inorganic layer.
Forming Organic EL Element
[0057] Using a known method, the base coating film 11 and the
organic EL element 18 (the TFTs 12, the flattening film 13, the
first electrodes 14, the edge cover 15, the organic EL layers 16
(the hole injection layer 1, the hole transport layer 2, the
light-emitting layer 3, the electron transport layer 4, and the
electron injection layer 5), and the second electrode 17) are
formed on the surface of the base substrate 10, which is made from
a polyimide resin, for example.
Forming Sealing Film
[0058] First, as illustrated in FIG. 7, the first inorganic layer
19 is formed by using a mask Ma to form an inorganic insulating
film, such as a silicon nitride film, through plasma CVD at a
thickness of approximately 500 nm so as to cover the organic EL
element 18 formed in the above-described formation of the organic
EL element (forming a first inorganic layer).
[0059] Next, as illustrated in FIG. 8, an organic film 20a composed
of the organic material M, such as an acrylate, is formed at a
thickness of from approximately 100 nm to 300 nm over the entire
surface of the substrate on which the first inorganic layer 19 has
been formed, using the film formation method described above in the
first embodiment (forming an organic film).
[0060] Then, as illustrated in FIG. 9, the second inorganic layer
21 is formed so as to overlap with the first inorganic layer 19 by
using a mask Mb to form an inorganic insulating film, such as a
silicon nitride film, through plasma CVD at a thickness of
approximately 200 nm, onto the substrate on which the organic film
20a has been formed (forming a second inorganic film). Here, the
area of the opening in the mask Mb is smaller than the area of the
opening in the mask Ma (see FIGS. 7 and 9).
[0061] Furthermore, as illustrated in FIG. 10, the organic layer 20
is formed by using the second inorganic layer 21 as a mask and
ashing (using plasma P, for example) the organic film 20a exposed
from the second inorganic layer 21 (forming an organic layer). In
this manner, ashing the organic film 20a using the second inorganic
layer 21 as a mask results in the locations of the perimeter edge
surfaces of the organic layer 20 coinciding with the locations of
the perimeter edge surfaces of the second inorganic layer 21. In
this specification, the (locations of the) perimeter edge surfaces
coinciding refers to a state in which skew between the perimeter
edge surfaces is within from 1 .mu.m to 2 .mu.m.
[0062] Finally, as illustrated in FIG. 11, the third inorganic
layer 22 is formed by using the mask Ma to form an inorganic
insulating film, such as a silicon nitride film, through plasma CVD
at a thickness of approximately from 400 nm to 500 nm on the
substrate on which the organic layer 20 has been formed so as to
cover the perimeter edge surfaces of the organic layer 20 and the
second inorganic layer 21 (forming a third inorganic layer). Here,
the mask Ma, which was used when forming the first inorganic layer
19, is used to form the third inorganic layer 22, and thus the
perimeter edge surfaces of the third inorganic layer 22 conform to
(match) the perimeter edge surfaces of the first inorganic layer
19. In the present specification, "conform to" refers to the
perimeter edge surfaces of a thin film formed later matching, to a
certain degree, the perimeter edge surfaces of a thin film formed
earlier, due to the films being formed using the same mask. The
perimeter edge surfaces do not strictly match each other due to the
alignment precision of the mask, flowing of the CVD film formation
material, and the like.
[0063] The organic EL display device 30 of the present embodiment
can be manufactured in this manner.
[0064] As described thus far, according to the method of
manufacturing the organic EL display device 30 of the present
embodiment, the organic film 20a can be formed having a uniform
thickness. In the formation of the organic layer, the organic layer
20 is formed having removed the organic film 20a exposed from the
second inorganic layer 21, and the perimeter edge surfaces of the
second inorganic layer 21 coincide with the perimeter edge surfaces
of the organic layer 20 as a result. This makes it possible to form
circumferential end parts of the organic layer 20 in a precise
manner. Additionally, the third inorganic layer 22 is provided so
as to cover the perimeter edge surfaces of the second inorganic
layer 21, and thus the sealing film 23, in which the first
inorganic layer 19, the organic layer 20, the second inorganic
layer 21, and the third inorganic layer 22 are layered in that
order, can be formed. The sealing properties of the sealing film 23
can therefore be ensured. Thus, the circumferential end parts of
the organic layer 20 can be formed with precision to achieve a
narrower frame while at the same time ensuring the sealing
properties of the sealing film 23.
[0065] Furthermore, according to the method of manufacturing the
organic EL display device 30 of the present embodiment, in the
formation of the organic layer, the organic film 20a exposed from
the second inorganic layer 21 is removed using the second inorganic
layer 21 as a mask. It is therefore not necessary to prepare a
separate mask, and the locations of the perimeter edge surfaces of
the second inorganic layer 21 can be caused to coincide with the
locations of the perimeter edge surfaces of the organic layer
20.
[0066] In the present embodiment, the example of the organic EL
layer including the five-layer structure including the hole
injection layer, the hole transport layer, the light-emitting
layer, the electron transport layer, and the electron injection
layer is given. It is also possible that, for example, the organic
EL layer may include a three-layer structure including a hole
injection-cum-transport layer, a light-emitting layer, and an
electron transport-cum-injection layer.
[0067] In the present embodiment, the example of the organic EL
display device including the first electrode as an anode and the
second electrode as a cathode is given. However, the disclosure is
also applicable to an organic EL display device, in which the
layers of the structure of the organic EL layer are in reverse
order, with the first electrode being a cathode and the second
electrode being an anode.
[0068] In the present embodiment, the example of the organic EL
display device including the element substrate in which, the
electrode of the TFT connected to the first electrode is the drain
electrode is given. However, the disclosure is also applicable to
an organic EL display device including an element substrate, in
which the electrode of the TFT connected to the first electrode is
referred to as the source electrode.
[0069] Although the present embodiment describes an organic EL
display device as an example of a display device, the disclosure
can be applied in display devices including a plurality of
electro-optical elements that are driven by an electrical current.
For example, the disclosure is applicable to display devices
including quantum dot light emitting diodes (QLEDs), which are
light emitting elements using a quantum dot-containing layer.
INDUSTRIAL APPLICABILITY
[0070] As described above, the disclosure is applicable in flexible
display devices.
REFERENCE SIGNS LIST
[0071] F Vapor deposition film [0072] G Vaporized material [0073] M
Organic material [0074] S Film formed substrate [0075] 10 Base
substrate [0076] 18 Organic EL element (light emitting element)
[0077] 19 First inorganic layer [0078] 20 Organic layer [0079] 20a
Organic film [0080] 21 Second inorganic layer [0081] 22 Third
inorganic layer [0082] 23 Sealing film [0083] 30 Organic EL display
device [0084] 50 Vaporizing chamber [0085] 60 Film formation
chamber
* * * * *