U.S. patent application number 10/370577 was filed with the patent office on 2003-08-28 for fabrication system and a fabrication method of light emitting device.
Invention is credited to Murakami, Masakazu, Ohtani, Hisashi, Yamazaki, Shunpei.
Application Number | 20030162314 10/370577 |
Document ID | / |
Family ID | 27655423 |
Filed Date | 2003-08-28 |
United States Patent
Application |
20030162314 |
Kind Code |
A1 |
Yamazaki, Shunpei ; et
al. |
August 28, 2003 |
Fabrication system and a fabrication method of light emitting
device
Abstract
An evaporation apparatus with high utilization efficiency for EL
materials and excellent film uniformity is provided. The invention
is an evaporation apparatus having a movable evaporation source and
a substrate rotating unit, in which the space between an
evaporation source holder and a workpiece (substrate) is narrowed
to 30 cm or below, preferably 20 cm, more preferably 5 to 15 cm, to
improve the utilization efficiency for EL materials. In
evaporation, the evaporation source holder is moved in the
X-direction or the Y-direction, and the workpiece (substrate) is
rotated for deposition. Therefore, film uniformity is improved.
Inventors: |
Yamazaki, Shunpei; (Tokyo,
JP) ; Murakami, Masakazu; (Atsugi, JP) ;
Ohtani, Hisashi; (Tochigi, JP) |
Correspondence
Address: |
FISH & RICHARDSON P.C.
1425 K STREET, N.W.
11TH FLOOR
WASHINGTON
DC
20005-3500
US
|
Family ID: |
27655423 |
Appl. No.: |
10/370577 |
Filed: |
February 24, 2003 |
Current U.S.
Class: |
438/46 ; 118/730;
438/503 |
Current CPC
Class: |
C23C 14/12 20130101;
C23C 14/505 20130101; C23C 14/24 20130101 |
Class at
Publication: |
438/46 ; 438/503;
118/730 |
International
Class: |
H01L 021/00; H01L
021/20; C23C 016/00; C30B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2002 |
JP |
2002-047508 |
Claims
What is claimed is:
1. A fabrication system having a deposition apparatus, in which an
evaporation material is evaporated from an evaporation source
disposed opposite to a substrate and deposited over the substrate,
said system comprising: a film-formation chamber where the
substrate is placed, said film-formation chamber comprising: the
evaporation source; means for moving the evaporation source; and
means for rotating the substrate, wherein the evaporation source is
moved and the substrate is rotated simultaneously for
deposition.
2. The fabrication system according to claim 1, wherein a space
between the evaporation source and the substrate is 30 cm or
below.
3. The fabrication system according to claim 1, wherein the
film-formation chamber is joined to a chamber for vacuuming the
film-formation chamber.
4. The fabrication system according to claim 1, wherein the
evaporation source is moved in at least of an X-direction and a
Y-direction.
5. The fabrication system according to claim 1, wherein the
evaporation material comprises an organic compound material.
6. The fabrication system according to claim 1, said means for
moving the evaporation source is an evaporation source holder.
7. The fabrication system according to claim 1, said means for
rotating the substrate is a substrate holder.
8. A fabrication system having a deposition apparatus, comprising:
a loading chamber; a transport chamber joined to the loading
chamber; and a film-formation chamber joined to the transport
chamber, wherein the film-formation chamber includes: an
evaporation source; means for moving the evaporation source; and
means for rotating the substrate, wherein the evaporation source is
moved and the substrate is rotated simultaneously for
deposition.
9. The fabrication system according to claim 8, wherein a space
between the evaporation source and the substrate is 30 cm or
below.
10. The fabrication system according to claim 8, wherein the
film-formation chamber is joined to a chamber for vacuuming the
film-formation chamber.
11. The fabrication system according to claim 8, wherein the
evaporation source is moved in at least of an X-direction and a
Y-direction.
12. The fabrication system according to claim 8, wherein the
evaporation material comprises an organic compound material.
13. The fabrication system according to claims 8, said means for
moving the evaporation source is an evaporation source holder.
14. The fabrication system according to claims 8, said means for
rotating the substrate is a substrate holder.
15. A fabrication system having a deposition apparatus, in which an
evaporation material is evaporated from an evaporation source
disposed opposite to a substrate and deposited over the substrate,
comprising: a film-formation chamber where the substrate is placed
comprising: the evaporation source; means for moving the
evaporation source; and wherein the evaporation source is moved
zigzag.
16. The fabrication system according to claim 15, wherein a space
between the evaporation source and the substrate is 30 cm or
below.
17. The fabrication system according to claim 15, wherein the
film-formation chamber is joined to a chamber for vacuuming the
film-formation chamber.
18. The fabrication system according to claim 15, wherein the
evaporation source is moved in at least of an X-direction and a
Y-direction.
19. The fabrication system according to claim 15, wherein the
evaporation material comprises an organic compound material.
20. The fabrication system according to claim 15, said means for
moving the evaporation source is an evaporation source holder.
21. A fabrication system having a deposition apparatus, the
fabrication system comprising: a loading chamber; a transport
chamber joined to the loading chamber; and a film-formation chamber
joined to the transport chamber, wherein the film-formation chamber
includes: an evaporation source; means for moving the evaporation
source; and wherein the evaporation source is moved zigzag.
22. The fabrication system according to claim 21, wherein a space
between the evaporation source and the substrate is 30 cm or
below.
23. The fabrication system according to claim 21, wherein the
film-formation chamber is joined to a chamber for vacuuming the
film-formation chamber.
24. The fabrication system according to claim 21, wherein the
evaporation source is moved in at least of an X-direction and a
Y-direction.
25. The fabrication system according to claim 21, wherein the
evaporation material comprises an organic compound material.
26. The fabrication system according to claim 21, said means for
moving the evaporation source is an evaporation source holder.
27. A fabrication method of a light emitting device, comprising:
rotating a substrate in a film-formation chamber; evaporating an
evaporation material comprising an organic compound from an
evaporation source in the film-formation chamber; changing a
relative position of the evaporation source with respect to the
substrate; and depositing a layer comprising said organic compound
over said substrate in the film-formation chamber.
28. A fabrication method of a light emitting device, comprising:
evaporating an evaporation material comprising an organic compound
from an evaporation source in a film-formation chamber; changing a
relative position of the evaporation source with respect to the
substrate zigzag; and depositing a layer comprising said organic
compound over said substrate in the film-formation chamber.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a fabrication apparatus
having a deposition apparatus for use in deposition of materials
allowed to be deposited by evaporation (hereafter, they are called
evaporation materials). Particularly, the invention is an effective
technique when organic materials are used as the evaporation
materials.
[0003] 2. Description of the Related Art
[0004] In recent years, the research of light emitting devices
having EL elements as self-luminous elements has been conducted
actively. In particular, a light emitting device using organic
materials as EL materials is receiving attention. The light
emitting device is also called an organic EL display or an organic
light emitting diode.
[0005] In addition, the EL element has an anode, a cathode, and a
layer containing organic compounds where an electric field is
applied to obtain electroluminescence (hereafter, it is denoted by
EL layer). Electroluminescence in the organic compounds has light
emission (fluorescence) in returning from the singlet excited state
to the ground state, and light emission (phosphorescence) in
returning from the triplet excited state to the ground state. The
light emitting devices fabricated by the deposition apparatus and a
deposition method of the invention can be adapted to in either case
of light emission.
[0006] As different from liquid crystal display devices, the light
emitting devices have characteristics in that they have no problem
about the viewing angle because they are a self-luminous type. More
specifically, they are more suitable as displays used in outdoors
than the liquid crystal displays. Various forms for use have been
proposed.
[0007] The EL element has a structure in which the EL layer is
sandwiched between a pair of electrodes. The EL layer generally has
a multilayer structure. Typically, the multilayer structure of
anode/hole transport layer/emissive layer/electron transport
layer/cathode is named, which was proposed by Tang, Eastman Kodak
Company. This structure has significantly high luminous efficiency,
which is adopted for most of light emitting devices now under
research and development.
[0008] Furthermore, other than this, these structures are fine to
be layered over the anode in these orders: the structure of hole
injection layer/hole transport layer/light emitting layer/electron
transport layer, and alternatively the structure of hole injection
layer/hole transport layer/light emitting layer/electron transport
layer/electron injection layer. Moreover, it is acceptable to dope
fluorescent dyes to the light emitting layer. Besides, it is fine
that these layers are all formed of low weight molecular materials
or all formed of polymeric materials.
[0009] In this specification, the entire layers disposed between
the anode and the cathode are collectively called the EL layer.
Accordingly, the hole injection layer, the hole transport layer,
the light emitting layer, the electron transport layer, and the
electron injection layer are all considered to be included in the
EL layer.
[0010] In the specification, the light emitting element formed of
the anode, the EL layer, and the cathode is called the EL element.
The EL element has two systems: the system in which the EL layer is
formed between two kinds of stripe electrodes disposed orthogonal
to each other (simple matrix system), and the system in which the
EL layer is formed between an opposite electrode and pixel
electrodes connected to TFTs and arranged in matrix (active matrix
system).
[0011] The EL materials forming the EL layer are generally
classified into low weight molecular (monomer based) materials and
polymeric (polymer based) materials. The low weight molecular
materials are mainly deposited by evaporation.
[0012] The EL materials tend to be deteriorated extremely, which
are easily oxidized and deteriorated by the existence of oxygen or
moisture. On this account, photolithography processes cannot be
performed after deposition. For patterning, deposition and
separation need to be conducted simultaneously with a mask having
opening parts (hereafter, it is called a mask). Therefore, almost
all the sublimed organic EL materials have been deposited over the
inner wall of a film-formation chamber or a wall-deposition shield
(a protection plate for preventing the evaporation materials from
being deposited over the inner wall of the film-formation
chamber).
[0013] In a traditional evaporation apparatus, the space between a
substrate and an evaporation source has been set wider in order to
improve the uniformity of the film thickness, which has caused the
apparatus itself to be large-sized. Moreover, because of the wide
space between the substrate and the evaporation source, the
deposition rate becomes slow, the time required to exhaust the
inside of the film-formation chamber takes long time, and
throughput drops.
[0014] In addition, in the traditional evaporation apparatus, the
utilization efficiency for expensive EL materials is about one
percent or below, which is extremely low to cause the fabrication
costs of the light emitting device to be extremely high.
SUMMARY OF THE INVENTION
[0015] The EL materials are very expensive, and the unit price per
gram is far more expensive than the unit price per gram for gold.
Thus, it is desired to use them efficiently as much as possible.
However, in the traditional evaporation apparatus, the utilization
efficiency for expensive EL materials is low.
[0016] An object of the invention is to provide an evaporation
apparatus enhancing the utilization efficiency for the EL materials
and excellent in uniformity and throughput.
[0017] In the invention, typically, the distance d between the
substrate and the evaporation source is narrowed to 30 cm or below
in evaporation, and the utilization efficiency for the evaporation
materials and throughput are improved significantly. The distance d
between the space between the substrate and the evaporation source
is narrowed, and thus the size of the film-formation chamber can be
small-sized. Downsizing reduces the capacity of the film-formation
chamber. Therefore, the time required for vacuuming can be
shortened, the total amount of impurities inside the film-formation
chamber can be decreased, and impurities (moisture and oxygen) can
be prevented from being mixed in the highly purified EL materials.
According to the invention, a response to the realization of
further highly purified evaporation materials in future is
feasible.
[0018] In addition to this, the invention is characterized in that
an evaporation source holder having a container sealed with an
evaporation material is moved to a substrate at a certain pitch in
a film-formation chamber. In this specification, a fabrication
system having the evaporation apparatus equipped with the movable
evaporation source holder is called a moving cell cluster system. A
single evaporation source holder can hold two or more crucibles,
preferably four or six crucibles. In the invention, the evaporation
source holder is moved. Thus, when the movement speed is fast, a
mask is barely heated. Therefore, deposition failure caused by a
thermally deformed mask can be suppressed as well.
[0019] A configuration of the invention to be disclosed in the
specification is a fabrication system having a deposition
apparatus, in which an evaporation material is evaporated from an
evaporation source disposed opposite to a substrate and deposited
over the substrate, said system comprising:
[0020] a film-formation chamber where the substrate is placed, said
has film-formation chamber comprising:
[0021] the evaporation source; and
[0022] means for moving (a unit adapted to move) the evaporation
source,
[0023] wherein the evaporation source is moved in the X-direction
or the Y-direction, or zigzag for deposition.
[0024] Moreover, it is acceptable that a mechanism for rotating the
substrate is disposed in the film-formation chamber, the substrate
is rotated and the evaporation source is moved simultaneously in
evaporation for deposition excellent in film thickness
uniformity.
[0025] A configuration of the invention to be disclosed in the
specification is a fabrication system having a deposition
apparatus, the deposition apparatus in which an evaporation
material is evaporated from an evaporation source disposed opposite
to a substrate and deposited over the substrate,
[0026] a film-formation chamber where the substrate is placed
has:
[0027] the evaporation source;
[0028] means for moving (a unit adapted to move) the evaporation
source; and
[0029] means for rotating (a unit adapted to rotate) the
substrate,
[0030] wherein the evaporation source is moved and the substrate is
rotated simultaneously for deposition.
[0031] It is possible to form a fabrication system of a
multi-chamber system. Another configuration of the invention is a
fabrication system having a deposition apparatus, the fabrication
system has:
[0032] a loading chamber;
[0033] a transport chamber joined to the loading chamber;
[0034] a film-formation chamber joined to the transport
chamber,
[0035] wherein the film-formation chamber includes:
[0036] an evaporation source;
[0037] means for moving (a unit adapted to move) the evaporation
source;
[0038] means for rotating (a unit adapted to rotate) the
substrate,
[0039] wherein the evaporation source is moved and the substrate is
rotated simultaneously for deposition.
[0040] In the configurations, the space between the evaporation
source and the substrate is characterized by being 30 cm or below,
preferably 5 to 15 cm.
[0041] In the configurations, the film-formation chamber is
characterized by being joined to a vacuum processing chamber for
vacuuming the film-formation chamber.
[0042] In the configurations, the evaporation source is
characterized by being moved in at least of the X-direction and the
Y-direction. In the configurations, a mask is disposed between the
substrate and the evaporation source, and the mask is characterized
by being a mask formed of a metal material having a low coefficient
of thermal expansion.
[0043] In the configurations, the evaporation material is
characterized by being an organic compound or a metal material.
[0044] When main processes, in which impurities such as oxygen and
moisture are mixed in EL materials or metal materials for
evaporation, are named, a process of setting the EL materials or
the metal materials in the evaporation apparatus before evaporation
and an evaporation process can be considered.
[0045] Generally, a container for storing an EL material is housed
in a brown glass bottle that is closed with a plastic cap. It is
also considered that the degree of sealing the container for
storing the EL material is not enough.
[0046] Traditionally, in deposition by evaporation methods, a
predetermined amount of an evaporation material contained in a
container (glass bottle) is taken out and transferred to a
container (typically, it is a crucible and an evaporation boat)
placed at the position facing to a workpiece in the evaporation
apparatus. In the transfer operation, impurities are likely to be
mixed. More specifically, oxygen, moisture and other impurities are
likely to be mixed, which are one cause of deteriorating the EL
element.
[0047] In transferring the material from the glass bottle to the
container, for example, it is considered that human hands transfer
the material in a pretreatment chamber equipped with gloves in the
evaporation apparatus. However, when the pretreatment chamber is
equipped with the gloves, the chamber cannot be vacuumed, and thus
the operation is done at an atmospheric pressure. Even though the
operation is done in a nitrogen atmosphere, it has been difficult
to reduce moisture and oxygen in the pretreatment chamber as much
as possible. It is also considered to use a robot. However, the
evaporation material is powder, and thus it is difficult to
manufacture a transfer robot. Therefore, it has been difficult to
manufacture a total closed system allowing that the process steps
from the step of forming the EL layer over a lower electrode to the
step of forming an upper electrode are all automated to avoid
impurities from being mixed.
[0048] Then, in the invention, a fabrication system is formed in
which EL materials and metal materials are directly housed in
containers to be placed in the evaporation apparatus and they are
deposited after transport, without using the traditional containers
typically the brown glass bottle as the container storing the EL
materials. The invention realizes preventing impurities from being
mixed in the highly purified evaporation materials. Alternatively,
it is acceptable that when the evaporation materials of the EL
materials are directly housed, the evaporation materials are
directly sublimed and purified in the container to be placed in the
evaporation apparatus, without separately housing the obtained
evaporation materials. According to the invention, a response to
the realization of further highly purified evaporation materials in
future is feasible. It is fine that metal materials are directly
housed in the container to be placed in the evaporation apparatus
and evaporated by resistance heating.
[0049] Desirably, a light emitting device manufacturer using the
evaporation apparatus requests a material manufacturer to directly
house the evaporation materials in the container to be placed in
the evaporation apparatus, the material manufacturer fabricates or
sells the evaporation materials.
[0050] Moreover, even though the highly purified EL materials are
provided by the material manufacturer, the traditional transfer
operation in the light emitting device manufacturer always has the
risk of mixing impurities not to keep the purity of EL materials,
which has given a limit in the purity. According to the invention,
the light emitting device manufacturer cooperates with the material
manufacturer to seek the reduction in mixed impurities, which
maintains the highly purified EL materials obtained by the material
manufacturer. Accordingly, the light emitting device manufacturer
can evaporate them without deteriorating the purity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] The teachings of the invention can be readily understood by
considering the following detailed description in conjunction with
the accompanying drawings, in which:
[0052] FIGS. 1A and 1B are diagrams illustrating Embodiment 1;
[0053] FIGS. 2A and 2B are cross sections illustrating Example
1;
[0054] FIG. 3 is a diagram illustrating the top view of a light
emitting device;
[0055] FIGS. 4A, 4B and 4C are cross sections illustrating Example
3;
[0056] FIG. 5 is a diagram illustrating a fabrication system of a
multi-chamber system (Example 4);
[0057] FIG. 6 is a diagram illustrating one example of moving an
evaporation source holder;
[0058] FIG. 7 is a diagram illustrating Example 5;
[0059] FIGS. 8A and 8B are diagrams illustrating crucible transport
in a setting chamber;
[0060] FIGS. 9A and 9B are diagrams illustrating the crucible
transport to the evaporation source holder in the setting chamber;
and
[0061] FIG. 10 is a diagram illustrating a fabrication system of a
multi-chamber system (Example 7).
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0062] The embodiment of the invention will be described below.
[0063] Embodiment
[0064] FIGS. 1A and 1B show a deposition apparatus of the
invention. FIG. 1A is a cross section, and FIG. 1B is a top
view.
[0065] In FIGS. 1A and 1B, reference numeral 11 denotes a
film-formation chamber, reference numeral 12 denotes a substrate
holder, reference numeral 13 denotes a substrate, reference numeral
14 denotes a mask, reference numeral 15 denotes a deposition shield
(deposition shutter), reference numeral 17 denotes an evaporation
source holder, reference numeral 18 denotes an evaporation
material, and reference numeral 19 denotes an evaporated
evaporation material.
[0066] Evaporation is conducted in the film-formation chamber 11
vacuumed at a vacuum degree of 5.times.10.sup.-3 Torrs (0.665 Pa)
or below, preferably vacuumed to 10.sup.-4 to 10.sup.-6 Pa. In
evaporation, the evaporation material is evaporated (vaporized) by
resistance heating beforehand. A shutter (not shown) is opened when
evaporation, which causes the material to fly in the direction of
the substrate 13. The evaporated evaporation material 19 is flown
upward, passed through opening parts disposed in the mask 14, and
selectively evaporated onto the substrate 13.
[0067] In the evaporation apparatus, the evaporation source holder
is configured of a crucible, a heater disposed outside the crucible
through a heat dissipating member, a heat insulating layer disposed
outside the heater, an outer casing for housing them, a cooling
pipe disposed around the outside of the outer casing, and a shutter
device for opening and closing the opening part of the outer casing
including the opening part of the crucible. In addition, in the
specification, the crucible is a cylindrical container having a
relatively large opening part, which is formed of a sintered
compact of BN, a compound sintered compact of BN and AIN, or
materials such as silica and graphite having resistance against
high temperatures, high pressures and reduced pressures.
[0068] It is fine that the deposition rate can be controlled by a
microcomputer.
[0069] In the evaporation apparatus shown in FIGS. 1A and 1B, the
distance d between the substrate 13 and the evaporation source
holder 17 is narrowed typically to 30 cm or below, preferably 20 cm
or below, more preferably 5 to 15 cm in evaporation. Thus, the
utilization efficiency for evaporation materials and throughput are
improved significantly.
[0070] The substrate holder 12 is provided with a mechanism for
rotating the substrate 13. The evaporation source holder 17 is
provided with a mechanism of moving the holder in the X-direction
or the Y-direction inside the film-formation chamber 11 as the
holder remains horizontal. Here, the example of moving the holder
in one direction was shown, which is not defined particularly. It
is acceptable that the evaporation source holder 17 is moved in the
X-direction or the Y-direction in a two-dimensional plane.
Alternatively, it is fine that an evaporation source holder 201 is
reciprocated in the X-direction or the Y-direction for several
times, moved slantly, or moved in an arc shape. The evaporation
source holder 201 may be moved with a constant acceleration. Also,
The evaporation source holder 201 source may be moved slowing down
or accelerating near an edge portion of a substrate. For example,
as one example shown in FIG. 6, it is fine to move the evaporation
source holder 201 zigzag. In FIG. 6, reference numeral 200 denotes
a substrate, reference numeral 201 denotes the evaporation source
holder, and reference numeral 202 denotes the direction of moving
the evaporation source holder. In FIG. 6, four crucibles can be
placed in the evaporation source holder 201. An evaporation
material 203a and an evaporation material 203b are filled in the
separate crucibles.
[0071] The evaporation apparatus shown in FIGS. 1A and 1B is
characterized in that the substrate 13 is rotated and the
evaporation source holder 17 is moved simultaneously in
evaporation, and thus deposition excellent in film thickness
uniformity is conducted.
[0072] It is acceptable that a deposition shutter is disposed in
the movable evaporation source holder 17. It is fine that an
organic compound provided in a single evaporation source holder is
not necessarily a single compound, which can be multiple compounds.
For example, it is acceptable that another organic compound (dopant
material) to be a dopant is provided in the evaporation source,
other than one kind of material provided as a luminous organic
compound. Preferably, an organic compound layer to be deposited is
configured of a host material and a luminescent material (dopant
material) having excitation energy lower than that of the host
material, and the excitation energy of dopant is designed to be
lower than the excitation energy in the hole transport region and
the excitation energy of the electron transport layer. Accordingly,
the molecular excitons of the dopant are prevented from being
diffused, and the dopant can emit light efficiently. When the
dopant is a carrier trap material, the recombination efficiency of
carrier can be enhanced as well. The case where a material capable
of converting triplet excitation energy into light emission is
mixed in the mixing region as a dopant is also included in the
invention. As the formation of the mixing region, it is fine that
the mixing region has a concentration gradient.
[0073] When a plurality of organic compounds is provided in a
single evaporation source holder, it is desirable that the
direction of the compounds evaporating is set slantly so as to
cross at the position of a workpiece for mixing the organic
compounds together. In order to conduct coevaporation, the
evaporation source holder 201 is acceptable to have four
evaporation materials (two kinds of host materials as the
evaporation materials a and two kinds of dopant materials as the
evaporation materials b) as shown in FIG. 6.
[0074] Because of narrowing the distance d between the substrate 13
and the evaporation source holder 17 to typically 30 cm or below,
preferably 5 to 15 cm, the mask 14 might be heated. Therefore, for
the mask 14, it is desirable to use metal materials having a low
coefficient of thermal expansion, which are hardly thermally
deformed, (for example, refractory metals such as tungsten,
tantalum, chromium, nickel and molybdenum or alloys containing
these elements, and materials such as stainless steel, inconel, and
hastelloy). For example, low thermal expansion alloys such as 42%
of nickel and 58% of iron are named. In order to cool the mask to
be heated, it is fine that the mask is provided with a mechanism
for circulating a cooling medium (cooling water and cooling
gas).
[0075] The mask 14 is used for selectively depositing a film, which
is not needed in depositing a film over throughout the surface
particularly.
[0076] The substrate holder 12 is provided with a permanent magnet,
which fixes the mask made of metal by magnetic force and the
substrate 13 sandwiched therebetween as well. The example of the
mask closely contacting the substrate 13 was shown here. However,
it is fine to properly provide a substrate holder for fixing the
substrate with some space or a mask holder.
[0077] The film-formation chamber 11 is joined to a vacuum
processing chamber for vacuuming the film-formation chamber. As the
vacuum processing chamber, a magnetic levitated turbo-molecular
pump, a cryopump, and a dry-sealed vacuum pump are provided.
Accordingly, the ultimate vacuum of the transport chamber can be
set at 10.sup.-5 to 10.sup.-6 Pa, and the back diffusion of
impurities from the pump side and an exhaust system can be
controlled. In order to prevent impurities from being introduced
into the apparatus, an inert gas such as nitrogen and a rare gas
are used for the gas to be introduced. The gases to be introduced
into the apparatus are highly purified by a gas purifier before
they are introduced into the apparatus. Therefore, the gas purifier
needs to be provided so that gases are highly purified and then
introduced into the evaporation apparatus. Accordingly, oxygen,
moisture and other impurities contained in the gases can be removed
beforehand. Thus, the impurities can be prevented from being
introduced into the apparatus.
[0078] It is fine that a plasma generating unit is provided in the
film-formation chamber 11, plasma (plasma generated by exciting one
or a plurality of kinds of gases selected from Ar, H, F, NF.sub.3
or O) is generated in the film-formation chamber in the state that
the substrate is not placed, deposited products deposited over the
inner wall of the film-formation chamber, the wall-deposition
shield, or the mask are vaporized and exhausted out of the
film-formation chamber for cleaning. In this manner, the inside of
the film-formation chamber can be cleaned without being exposed to
atmosphere at the time of maintenance. In addition, the vaporized
organic compounds in cleaning can be collected by the exhaust
system (vacuum pump) and recycled.
[0079] The invention formed of the configurations will be described
further in detail by examples below.
EXAMPLE
Example 1
[0080] Here, the process steps of fabricating an active matrix
light emitting device having a pixel part and a drive circuit on
the same substrate and including an EL element is exemplified and
described in FIGS. 2A and 2B.
[0081] First, as shown in FIG. 2A, a thin film transistor
(hereafter, it is called a TFT) 22 is formed over a substrate 21
having an insulated surface by publicly known fabrication process
steps. In a pixel part 20a, an n-channel TFT and a p-channel TFT
are formed. Here, the p-channel TFT for feeding current to an
organic light emitting element is illustrated in the drawing. It is
acceptable that the TFT for feeding current to the organic light
emitting element is the n-channel TFT or the p-channel TFT. In a
drive circuit 20b disposed around the pixel part, the n-channel
TFT, the p-channel TFT, and a CMOS circuit that complementally
combines them are formed. Here, an example is shown in which an
anode 23 formed of a transparent conductive oxide film (ITO (indium
tin oxide alloy), indium oxide-zinc oxide alloy
(In.sub.2O.sub.3--ZnO), and zinc oxide (ZnO)) is formed in matrix,
and then wiring lines to connect to an active layer of the TFTs are
formed. Subsequently, an insulating film 24 formed of an inorganic
material or an organic material for covering the end parts of the
anode 23 is formed.
[0082] Then, as shown in FIG. 2B, an organic compound layer (EL
layer) for forming the EL element is deposited.
[0083] First, the anode 23 is cleaned as pretreatment. As cleaning
of the anode surface, ultraviolet ray irradiation in a vacuum or
oxygen plasma processing is conducted to clean the anode surface.
As oxidation, it is fine that ultraviolet rays are irradiated in an
atmosphere containing oxygen as the substrate is heated at
temperatures of 100 to 120.degree. C., which is effective in the
case where the anode is an oxide such as ITO. As annealing, it is
acceptable that the substrate is annealed at a heating temperature
of 50.degree. C. or above where the substrate can resist in a
vacuum, preferably at temperatures of 65 to 150.degree. C., for
removing impurities such as oxygen and moisture attached in the
substrate and impurities such as oxygen and moisture in the thin
film deposited over the substrate. Particularly, the EL materials
tend to be deteriorated by impurities such as oxygen and moisture,
and thus annealing in a vacuum is effective before evaporation.
[0084] Subsequently, the substrate is transferred to a
film-formation chamber to be the deposition apparatus shown in
FIGS. 1A and 1B without being exposed to atmosphere, and a hole
transport layer, a hole injection layer, or a light emitting layer,
which are one of the organic compound layer, is properly layered
over the anode 23. Here, the evaporation source provided in the
film-formation chamber to be the deposition apparatus shown in
FIGS. 1A and 1B is heated for evaporation, and a hole injection
layer 25, a light emitting layer (R) 26, a light emitting layer (G)
27, and a light emitting layer (B) 28 are deposited. The light
emitting layer (R) is a light emitting layer emitting red light,
the light emitting layer (G) is a light emitting layer emitting
green light, and the light emitting layer (B) is a light emitting
layer emitting blue light. The deposition apparatus shown in FIGS.
1A and 1B is used for evaporation, which can significantly improve
the film thickness uniformity of the organic compound layer, the
utilization efficiency for evaporation materials, and
throughput.
[0085] Then, a cathode 29 is formed. It is acceptable that the
film-formation chamber shown in FIGS. 1A and 1B is used for forming
the cathode 29. The deposition apparatus shown in FIGS. 1A and 1B
is used for evaporation, which can significantly improve the film
thickness uniformity of the cathode, the utilization efficiency for
evaporation materials, and throughput.
[0086] As materials used for the cathode 29, it is considered
preferable to use metals having a small work function (typically,
metal elements in the Group 1 or the Group 2 of the periodic
table), or alloys containing them. The smaller the work function
is, the more enhanced luminous efficiency is. Thus, as the
materials used for the cathode, alloy materials containing Li
(lithium), which is one of alkali metals, are desirable among them.
The cathode also functions as the wiring line shared by the entire
pixels, which has a terminal electrode at an input terminal part
through the wiring lines.
[0087] Subsequently, it is preferable that the substrate is
encapsulated by a protection film, an encapsulation substrate, or
an encapsulation can, and the organic light emitting device is
fully blocked from the outside to prevent matters in the outside
from entering, the matters cause deterioration due to oxidation of
the EL layer by moisture and oxygen. It is acceptable to provide a
desiccant.
[0088] Then, an FPC (flexible printed circuit) is bonded to the
electrodes in an input and output terminal part with an anisotropic
conductive material. The anisotropic conductive material is formed
of a resin and conductive particles plated with Au having a
diameter of a few to a few hundreds micrometers in which the
conductive particles electrically connect the electrodes in the
input and output terminal part to the wiring lines formed in the
FPC.
[0089] It is fine to provide an optical film such as a circularly
polarizing plate configured of a polarizing plate and a retarder,
or to mount an IC chip, as required.
[0090] According to the process steps, a module type active matrix
light emitting device connected with the FPC is completed.
[0091] Moreover, the example that the anode is the transparent
conductive film to layer the anode, the organic compound layer, and
the cathode in this order was shown here. However, the invention is
not limited to this multilayer structure. It is acceptable that the
cathode, the organic compound layer, and the anode are sequentially
layered, or that the anode is a metal layer to layer the anode, the
organic compound layer, and a cathode having translucency in this
order.
[0092] The example of the top gate TFT was shown here as the
structure of the TFT. However, the invention can be adapted
regardless of the TFT structure. For example, it can be adapted to
a bottom gate (inversely staggered) TFT and a staggered TFT.
Example 2
[0093] FIG. 3 is a diagram illustrating the appearance of the top
view of an E1 module. In a substrate (it is also called a TFT
substrate) 35 where a countless number of TFTs are formed, a pixel
part 30 for display, drive circuits 31a and 31b for driving the
pixels in the pixel part, connecting parts for connecting a cathode
disposed over an EL layer to interconnect wiring lines, and
terminal parts 32 for bonding an FPC to connect external circuits
are disposed. The module is sealed with a substrate for
encapsulating the EL element and a sealing material 34.
[0094] In FIG. 3, the cross section of the pixel part is not
defined particularly. Here, the cross section shown in FIG. 2B is
exemplified. The module shown in FIG. 3 is a product after the
encapsulation process in which a protection film or an
encapsulation substrate was bonded to the product having the cross
sectional structure shown in FIG. 2B.
[0095] An insulating film is formed over the substrate, and the
pixel part and the drive circuits are formed in the upper part of
the insulating film. The pixel part is formed of a plurality of
pixels including a current controlling TFT and a pixel electrode
electrically connected to the drain. The drive circuits are formed
by using a CMOS circuit combining an n-channel TFT and a p-channel
TFT.
[0096] It is fine to form these TFTs by using publicly known
techniques.
[0097] The pixel electrode functions as the anode of the light
emitting element (organic light emitting element). An insulating
film called a bank is formed on both ends of the pixel electrode,
and an organic compound layer and the cathode of the light emitting
element are formed over the pixel electrode.
[0098] The cathode functions as the wiring line shared by the
entire pixels, which is electrically connected to the terminal part
connecting to the FPC through connection wiring lines. Devices
included in the pixel part and the drive circuits are all covered
with the cathode and a protection film. It is fine to bond the
substrate to a cover material (a substrate for encapsulation) with
an adhesive. It is acceptable that a recessed part is disposed in
the cover material to place a desiccant.
[0099] The example can be freely combined with the embodiment.
Example 3
[0100] The example 1 shows the example of fabricating the top gate
TFT (more specifically, it is a planar TFT) as the TFT 22. In this
example, a TFT 42 is used instead of the TFT 22. The TFT 42 used in
the example is a bottom gate TFT (more specifically, it is an
inversely staggered TFT), which is fine to be fabricated by
publicly known fabrication process steps.
[0101] First, as shown in FIG. 4A, the bottom gate TFT 42 is formed
over a substrate 41 having an insulated surface by publicly known
fabrication process steps. Here, the example is shown that the TFT
is formed and then an anode 43 is formed in matrix, the anode 43 is
formed of a metal layer (a conductive material containing one kind
or a plurality of elements selected from Pt, Cr, W, Ni, Zn, Sn and
In).
[0102] Subsequently, an insulating film 44 for covering the end
parts of the anode 43 is deposited, which is formed of an inorganic
material or an organic material.
[0103] Then, as shown in FIG. 4B, an organic compound layer for
forming an EL element (EL layer) is deposited. The substrate is
transferred to a film-formation chamber provided with an
evaporation source, and a hole transport layer, a hole injection
layer, or a light emitting layer, which are one of the organic
compound layer, is properly layered over the anode 43. Here,
evaporation is conducted in the deposition apparatus shown in FIGS.
1A and 1B, and a hole injection layer 45, a light emitting layer
(R) 46, a light emitting layer (G) 47, and a light emitting layer
(B) 48 are deposited. The deposition apparatus shown in FIGS. 1A
and 1B is used for evaporation, which can significantly improve the
film thickness uniformity of the organic compound layer, the
utilization efficiency for evaporation materials, and
throughput.
[0104] Subsequently, a cathode 49a to be an under layer is formed
by the deposition apparatus shown in FIGS. 1A and 1B. The
deposition apparatus shown in FIGS. 1A and 1B is used for
evaporation, which can significantly improve the film thickness
uniformity of the cathode 49a, the utilization efficiency for
evaporation materials, and throughput. For the cathode 49a to be
the under layer, it is preferable to use an extremely thin metal
film (a film deposited by coevaporation of aluminum and an alloy
such as MgAg, MgIn, AlLi and CaN or an element in the Group 1 or
the Group 2 of the periodic table) or a multilayer of these.
[0105] Then, an electrode 49b is formed over the cathode 49a (FIG.
4C. For the electrode 49b, it is fine to use a transparent
conductive oxide film (ITO (indium tin oxide alloy), indium
oxide-zinc oxide alloy (In.sub.2O.sub.3--ZnO), and zinc oxide
(ZnO)). The multilayer structure shown in FIG. 4C is the case where
light is emitted in the direction of arrows shown in the drawing
(light is passed through the cathode). Thus, preferably, conductive
materials having translucency are used as the electrode including
the cathode.
[0106] The process steps after this step are the same as those of
the module type active matrix light emitting device shown in the
example 1, thus omitting the description here.
[0107] The example can be freely combined with any of the
embodiment, the example 1 or 2.
Example 4
[0108] In this example, FIG. 5 shows a fabrication system of a
multi-chamber system in which the fabrication steps are fully
automated up to upper electrode fabrication.
[0109] In FIG. 5, 100a to 100k and 100m to 100u denote gates, 101
denotes a preparation chamber, 119 denotes a take-out chamber, 102,
104a, 108, 114 and 118 denote transport chambers, 105, 107 and 111
denote delivery chambers, 106R, 106B, 106G, 109, 110, 112 and 113
denote film-formation chambers, 103 denotes a pretreatment chamber,
117 denotes an encapsulation substrate loading chamber, 115 denotes
a dispenser chamber, 116 denotes an encapsulation chamber, 120a and
120b denote cassette chambers, and 121 denotes a tray mounting
stage.
[0110] Hereafter, the procedures will be shown that a substrate
formed with the TFT 22 and the anode 23 beforehand is transferred
in the fabrication system shown in FIG. 5 to form the multilayer
structure shown in FIG. 2B.
[0111] First, the substrate formed with the TFT and the anode 23 is
set in the cassette chamber 120a or the cassette chamber 120b. When
the substrate is a large-sized substrate (300 mm.times.360 mm, for
example), it is set in the cassette chamber 120b. When the
substrate is a general substrate (127 mm.times.127 mm, for
example), it is transferred to the tray mounting stage 121. Then,
several substrates are placed in a tray (300 mm.times.360 mm, for
example).
[0112] Then, the substrate is transferred from the transport
chamber 118 provided with a substrate transport mechanism to the
preparation chamber 101.
[0113] The preparation chamber 101 is joined to a vacuum processing
chamber. Preferably, the preparation chamber 101 is vacuumed and
then an inert gas is introduced to set at atmospheric pressure.
Subsequently, the substrate is transferred to the transport chamber
102 joined to the preparation chamber 101. The transport chamber is
vacuumed to keep a vacuum beforehand so as not to exist moisture
and oxygen.
[0114] The transport chamber 102 is joined to a vacuum processing
chamber for vacuuming the transport chamber. As the vacuum
processing chamber, a magnetic levitated turbo-molecular pump, a
cryopump or a dry-sealed vacuum pump is provided. Accordingly, the
ultimate vacuum in the transport chamber can be set at 10.sup.-5 to
10.sup.-6 Pa, and the back diffusion of impurities from the pump
side and an exhaust system can be controlled. In order to prevent
impurities from being introduced into the apparatus, an inert gas
such as nitrogen and a rare gas is used for the gas to be
introduced. The gases to be introduced into the apparatus are
highly purified by a gas purifier before introduced into the
apparatus. Therefore, the gas purifier needs to be equipped so that
gases are highly purified and then introduced into the evaporation
apparatus. Accordingly, oxygen, moisture and other impurities
contained in the gases can be removed beforehand. Thus, the
impurities can be prevented from being introduced into the
apparatus.
[0115] In order to remove moisture and other gases contained in the
substrate, the substrate is preferably annealed for deaeration in a
vacuum. It is fine that the substrate is transferred to the
pretreatment chamber 103 joined to the transport chamber 102 for
annealing. When the anode surface needs to be cleaned, it is fine
to carry the substrate to the pretreatment chamber 103 joined to
the transport chamber 102 for cleaning.
[0116] It is acceptable that an organic compound layer formed of
polymers is deposited over throughout the anode. The film-formation
chamber 112 is the film-formation chamber for depositing the
organic compound layer formed of polymers. In the example, the
example is shown that poly
(styrene-sulfonate)/poly(ethylenedioxythiophene) (PEDOT/PSS)
aqueous solution, which functions as the hole injection layer 25,
is deposited over throughout the surface. When the organic compound
layer is deposited in the film-formation chamber 112 by spin
coating, ink-jet deposition, or spraying, the surface of the
substrate for deposition is set upward under atmospheric pressure.
In the example, the delivery chamber 105 is provided with a
substrate reversing mechanism that properly reverses the substrate.
After deposition with aqueous solution, the substrate is preferably
transferred to the pretreatment chamber 103 and annealed in a
vacuum to vaporize moisture. In the example, the example of
depositing the hole injection layer 25 made of polymers was shown.
However, it is acceptable that the hole injection layer made of a
low weight molecular organic material is deposited by evaporation
based on resistance heating, or the hole injection layer 25 is not
provided in particular.
[0117] Subsequently, the substrate 104c is transferred from the
transport chamber 102 to the delivery chamber 105 without being
exposed to atmosphere. Then, the substrate 104c is transferred to
the transport chamber 104, and it is transferred to the
film-formation chamber 106R by a transport mechanism 104b to
properly deposit an EL layer 26 for emitting red light over the
anode 23. Here, it is deposited by evaporation based on resistance
heating. For the film-formation chamber 106R, the surface of the
substrate for deposition is set downward in the delivery chamber
105. Before the substrate is transferred, the film-formation
chamber is preferably vacuumed.
[0118] Evaporation is performed in the vacuumed film-formation
chamber 106R where the degree of vacuum is reduced to
5.times.10.sup.-3 Torrs (0.665 Pa) or below, for example,
preferably 10.sup.-4 to 10.sup.-6 Pa. In evaporation, the organic
compound is vaporized by resistance heating beforehand. A shutter
(not shown) is opened in evaporation, which causes the compound to
fly in the direction of the substrate. The vaporized organic
compound is flown upward, and deposited over the substrate through
the opening part (not shown) disposed in a metal mask (not
shown).
[0119] In the example, the deposition apparatus shown in FIGS. 1A
and 1B is used for deposition. The deposition apparatus shown in
FIGS. 1A and 1B is used for evaporation, which can significantly
improve the film thickness uniformity of the organic compound
layer, the utilization efficiency for evaporation materials, and
throughput.
[0120] Here, for the provision of full color, the substrate
undergoes deposition in the film-formation chamber 106R, and then
the substrate undergoes deposition sequentially in the
film-formation chambers 106G and 106B to properly form organic
compound layers 26 to 28 showing light emission of red, green and
blue.
[0121] The hole injection layer 25 and the desired EL layers 26 to
28 are formed over the anode 23, and then the substrate is
transferred from the transport chamber 104a to the delivery chamber
107 without being exposed to atmosphere. Subsequently, the
substrate is further transferred from the delivery chamber 107 to
the transport chamber 108 without being exposed to atmosphere.
[0122] After that, a transport mechanism provided in the transport
chamber 108 transfers the substrate to the film-formation chamber
110, and a cathode 29 formed of a metal layer is properly deposited
by an evaporation method based on resistance heating. Here, the
film-formation chamber 110 is an evaporation apparatus having Li
and Al in the evaporation source for evaporation by resistance
heating.
[0123] According to the process steps, the light emitting element
of the multilayer structure shown in FIG. 2B is fabricated.
[0124] Then, the substrate is transferred from the transport
chamber 108 to the film-formation chamber 113 without being exposed
to atmosphere, and a protection film formed of a silicon nitride
film or a silicon nitride oxide film is deposited. Here, the
film-formation chamber 113 is a sputtering apparatus provided with
a target made of silicon, a target made of silicon oxide, or a
target made of silicon nitride inside. For example, the target made
of silicon is used, and the atmosphere of the film-formation
chamber is set in a nitrogen atmosphere or an atmosphere containing
nitrogen and argon, which allows a silicon nitride film to be
deposited.
[0125] Subsequently, the substrate formed with the light emitting
element is transferred from the transport chamber 108 to the
delivery chamber 111 without being exposed to atmosphere, and it is
further transferred from the delivery chamber 111 to the transport
chamber 114.
[0126] After that, the substrate formed with the light emitting
element is transferred from the transport chamber 114 to the
encapsulation chamber 116. An encapsulation substrate with a
sealing material is preferably prepared in the encapsulation
chamber 116.
[0127] The encapsulation substrate is set in the encapsulation
substrate loading chamber 117 from outside. In order to remove
impurities such as moisture, annealing is preferably performed in a
vacuum beforehand. For example, the substrate is annealed in the
encapsulation substrate loading chamber 117. When the sealing
material is formed on the encapsulation substrate, the transport
chamber 114 is set at an atmospheric pressure, the encapsulation
substrate is transferred from the encapsulation substrate loading
chamber to the dispenser chamber 115 to form the sealing material
to be bonded to the substrate formed with the light emitting
element. Then, the encapsulation substrate formed with the sealing
material is transferred to the encapsulation chamber 116.
[0128] Subsequently, to degas the substrate formed with the light
emitting element, the substrate is annealed in a vacuum or an inert
atmosphere, and then the encapsulation substrate formed with the
sealing material is bonded to the substrate formed with the light
emitting element. Here, the example of forming the sealing material
on the encapsulation substrate was shown, which is not defined
particularly. It is fine that the sealing material is formed on the
substrate formed with the light emitting element.
[0129] Then, ultraviolet rays are irradiated onto a set of the
bonded substrates by an ultraviolet ray irradiation mechanism
provided in the encapsulation chamber 116 to cure the sealing
material. Here, a UV curable resin was used as the sealing
material, which is not limited particularly as long as it is an
adhesive.
[0130] Subsequently, the set of the bonded substrates is
transferred from the encapsulation chamber 116 to the transport
chamber 114, and from the transport chamber 114 to the take-out
chamber 119, for taking it out.
[0131] As described above, the fabrication system shown in FIG. 5
is used, which does not expose the light emitting element to
ambient air entirely until it is encapsulated in the enclosed
space. Thus, a highly reliable light emitting device can be
fabricated. A vacuum and a nitrogen atmosphere at an atmospheric
pressure are repeated in the transport chamber 114, but desirably,
the transport chambers 102, 104a and 108 are always kept in a
vacuum.
[0132] Alternatively, a deposition apparatus of an inline system is
feasible.
[0133] Hereafter, the procedures will be shown that the substrate
formed with a TFT and an anode beforehand is transferred to the
fabrication system shown in FIG. 5 and the multilayer structure
shown in FIG. 4C is formed.
[0134] First, a substrate formed with the TFT and the anode 43 is
set in the cassette chamber 120a or the cassette chamber 120b, as
similar to the case of forming the multilayer structure shown in
FIG. 2A.
[0135] Then, the substrate is transferred from the transport
chamber 118 provided with the substrate transport mechanism to the
preparation chamber 101. Subsequently, the substrate is transferred
to the transport chamber 102 joined to the preparation chamber
101.
[0136] In order to remove moisture and other gases contained in the
substrate, the substrate is preferably annealed for deaeration in a
vacuum. It is fine that the substrate is transferred to the
pretreatment chamber 103 joined to the transport chamber 102 for
annealing. When the anode surface needs to be cleaned, the
substrate is transferred to the pretreatment chamber 103 joined to
the transport chamber 102 for cleaning.
[0137] It is acceptable that an organic compound layer made of
polymers is formed over throughout the anode. The film-formation
chamber 112 is a film-formation chamber for depositing the organic
compound layer made of polymers. For example, it is fine that
poly(styrenesulfonate)/poly(ethyle- nedioxythiophene) (PEDOT/PSS)
aqueous solution, which functions as a hole injection layer 45, is
deposited over throughout the surface. When the organic compound
layer is deposited in the film-formation chamber 112 by spin
coating, ink-jet deposition, and spraying, the surface of the
substrate for deposition is set upward under atmospheric pressure.
The delivery chamber 105 is provided with the substrate reversing
mechanism that reverses the substrate properly. After deposition
with the aqueous solution, the substrate is preferably transferred
to the pretreatment chamber 103 for annealing in a vacuum to
vaporize moisture.
[0138] Subsequently, the substrate 104c is transferred from the
transport chamber 102 to the delivery chamber 105 without being
exposed to atmosphere, and then the substrate 104c is transferred
to the transport chamber 104. The substrate is transferred to the
film-formation chamber 106R by the transport mechanism 104b, and an
EL layer 46 for emitting red light is properly deposited over the
anode 43. Here, it is deposited by evaporation using the deposition
apparatus shown in FIGS. 1A and 1B. The deposition apparatus shown
in FIGS. 1A and 1B is used for evaporation, which can significantly
improve the film thickness uniformity of the organic compound
layer, the utilization efficiency for evaporation materials, and
throughput.
[0139] Here, for the provision of full color, the substrate
undergoes deposition in the film-formation chamber 106R, and then
the substrate undergoes deposition in the film-formation chambers
106G and 106B to properly deposit organic compound layers 46 to 48
showing light emission of red, green and blue.
[0140] The hole injection layer 45 and the desired EL layer 46 to
48 are formed over the anode 43, and then the substrate is
transferred from the transport chamber 104a to the delivery chamber
107 without being exposed to atmosphere. Then, the substrate is
further transferred from the delivery chamber 107 to the transport
chamber 108 without being exposed to atmosphere.
[0141] After that, the substrate is transferred to the
film-formation chamber 110 by the transport mechanism equipped in
the transport chamber 108, and a cathode (under layer) 49a formed
of an extremely thin metal film (a film deposited by codeposition
method of aluminum and an alloy such as MgAg, MgIn, AlLi and CaN or
an element in the Group 1 or the Group 2 of the periodic table) by
the deposition apparatus shown in FIGS. 1A and 1B. The cathode
(under layer) 49a formed of the thin metal layer is deposited.
Then, the substrate is transferred to the film-formation chamber
109 where an electrode (upper layer) 49b formed of a transparent
conductive film (ITO (indium tin oxide alloy), indium oxide-zinc
oxide alloy (In.sub.2O.sub.3--ZnO), and zinc oxide (ZnO)) is
deposited by sputtering to properly form the electrodes 49a and 49b
of the multilayer of the thin metal layer and the transparent
conductive film.
[0142] According to the process steps, the light emitting element
of the multilayer structure shown in FIG. 4C is fabricated. The
light emitting element of the multilayer structure shown in FIG. 4C
emits light in the direction indicated by arrows in the drawing,
which emits light inversely as the light emitting element shown in
FIG. 2B.
[0143] The process steps after this are the same as the procedures
of fabricating the light emitting device having the multilayer
structure shown in FIG. 2A, thus omitting the description.
[0144] As described above, when the fabrication system shown in
FIG. 5 is used, the multilayer structures shown in FIGS. 2B and 4C
can be fabricated separately. The deposition apparatus shown in
FIGS. 1A and 1B is used for evaporation, which can significantly
improve the film thickness uniformity of the organic compound
layer, the utilization efficiency for evaporation materials, and
throughput.
[0145] The example can be combined freely with any of the
embodiment, and the examples 1 to 3.
Example 5
[0146] FIG. 7 shows an explanatory view of a fabrication system of
this example.
[0147] In FIG. 7, reference numeral 61a denotes a first container
(crucible), and 61b denotes a second container for separating the
first container from atmosphere to prevent the first container from
being contaminated. Reference numeral 62 denotes a powder EL
material highly purified. Reference numeral 63 denotes a vacuumable
chamber, reference numeral 64 denotes a heating unit, reference
numeral 65 denotes a workpiece, and reference numeral 66 denotes a
film. Reference numeral 68 denotes a material manufacturer that is
a manufacturer (typically, a raw material handler) producing and
purifying organic compound materials to be the evaporation
materials, and reference numeral 69 denotes a light emitting device
manufacturer having an evaporation apparatus that is a manufacturer
(typically, a production plant) of light emitting devices.
[0148] The flow of the manufacturing system of the example will be
described below.
[0149] First, the light emitting device manufacturer 69 places an
order 60 to the material manufacturer 68. The material manufacturer
68 prepares the first container and the second container in
compliance with the order 60. Then, the material manufacturer
purifies or houses the highly purified EL material 62 in the first
container 61a in a clean room environment with sufficient attention
to impurities (oxygen and moisture) not to be mixed. After that,
the material manufacturer 68 preferably seals the first container
61a in the second container 61b so as not to attach unnecessary
impurities to the inside or outside of the first container in the
clean room environment. In sealing, the inside of the second
container 61b is preferably vacuumed or filled with an inert gas.
Preferably, the first container 61a and the second container 61b
are cleaned before the highly purified EL material 62 is purified
or housed.
[0150] In the example, the first container 61a is placed in a
chamber as it is in evaporation later. It is acceptable that the
second container 61b is a packaging film with a barrier property
for blocking oxygen and moisture from being mixed. However, the
second container is preferably a strong container in a cylindrical
shape or a box shape having a light shielding property for
automatic pickup.
[0151] Subsequently, as the first container 61a is sealed in the
second container 61b, the material manufacturer 68 makes transport
67 to the light emitting device manufacturer 69.
[0152] Then, as the first container 61a is sealed in the second
container 61b, they are placed in the vacuumable process chamber
63. The process chamber 63 is an evaporation chamber having the
heating unit 64 and a substrate holder (not shown) provided inside.
After that, the process chamber 63 is vacuumed and cleaned with
oxygen and moisture reduced as much as possible, the first
container 61a is taken out of the second container 61b, and then it
is placed in the heating unit 64 as a vacuum is maintained.
Accordingly, an evaporation source can be prepared. The workpiece
(substrate) 65 is placed so as to face to the first container
61a.
[0153] Subsequently, the heating unit 64 for resistance heating
heats the evaporation materials, and the film 66 can be deposited
over the surface of the workpiece 65 facing to the evaporation
source. The deposited film 66 thus obtained does not contain
impurities. When the deposited film 66 is used to complete a light
emitting element, high reliability and high brightness can be
realized.
[0154] In this manner, the first container 61a is placed in the
process chamber 63 with never exposed to atmosphere, and
evaporation can be conducted as the purity is kept at the level
that the evaporation material 62 has been housed by the material
manufacturer. The material manufacturer directly houses the EL
material 62 in the first container 61a, which can provide just a
necessary amount for the light emitting device manufacturer and
allows efficient use of relatively expensive EL materials.
[0155] In the traditional evaporation methods based on resistance
heating, the utilization ratio of materials is low. For example,
the following is a method of enhancing the utilization ratio. A new
EL material is housed in the crucible at the time of maintenance of
the evaporation apparatus, a first time evaporation is conducted in
this state, and then unevaporated residual materials remain. Then,
in the next time deposition, an EL material is newly replenished on
the residual materials for evaporation, and replenishing is
repeated in the subsequent evaporation until maintenance. This
method can enhance the utilization ratio, but the method can cause
the residual materials to be contamination. An operator replenishes
the materials, and thus there is the possibility that oxygen and
moisture are mixed into the evaporation materials in replenishing
to degrade the purity. The crucible is repeatedly used for
evaporation for several times, and discarded at the time of
maintenance. In order to prevent the contamination by impurities,
it can be considered that a new EL material is housed in a crucible
at every time of evaporation and the crucible is also discarded at
every time of evaporation, but fabrication costs become high.
[0156] The fabrication system can eliminate the traditional glass
bottles housing the evaporation materials and the operation to
transfer the materials from the glass bottle to the crucible, which
can prevent impurities from being mixed. In addition to this,
throughput is improved as well.
[0157] According to the example, the fabrication system can be
realized that allows full automation to enhance throughput, and a
total closed system can be realized that allows preventing
impurities from being mixed in the evaporation material 62 purified
by the material manufacturer 68.
[0158] The EL materials are exemplified for description. However,
in the example, the metal layers to be the cathode and the anode
can be deposited by evaporation based on resistance heating as
wells. When the cathode is formed by resistance heating, the EL
element can be fabricated without varying the electric
characteristics (on-state current, off-state current, Vth, and
S-value) of the TFT 22.
[0159] As for the metal materials, it is acceptable that the metal
materials are housed in the first container beforehand in the
similar manner, the first container is placed in the evaporation
apparatus as it is, and the materials are evaporated by resistance
heating to deposit a film.
[0160] The example can be combined feely with any of the
embodiment, and the examples 1 to 4.
Example 6
[0161] In this example, the form of the container for transport
will be described in detail with FIG. 8A. The second container for
transport has an upper part 721a and a lower part 721b. The second
container has a fixing unit 706 disposed in the upper part of the
second container for fixing the first container, a spring 705 for
applying pressure to the fixing unit, a gas inlet 708 disposed in
the lower part of the second container, which is a gas line for
reducing and keeping pressure in the second container, an O-ring
for fixing the upper container 721a to the lower container 721b,
and a fastener 702. In the second container, the first container
701 sealed with the purified evaporation material is placed. It is
fine that the second container is formed of a material containing
stainless steel, and the first container 701 is formed of a
material having titanium.
[0162] In the material manufacturer, the purified evaporation
material is sealed in the first container 701. Then, the upper part
721a of the second container is set on the lower part 721b of the
second container through the O-ring, the fastener 702 fixes the
upper container 721a to the lower container 721b, and then the
first container 701 is sealed in the second container. After that,
the inside of the second container is depressurized through the gas
inlet 708 and substituted by a nitrogen atmosphere, and the spring
705 is controlled to fix the first container 701 by the fixing unit
706. It is fine to place a desiccant in the second container. In
this manner, when the inside of the second container is kept in a
vacuum, a reduced pressure, or a nitrogen atmosphere, even slight
oxygen and moisture can be prevented from attaching to the
evaporation materials.
[0163] In this state, the containers are transported to the light
emitting device manufacturer, and the first container 701 is placed
in the film-formation chamber. After that, the evaporation material
is sublimated by heating to deposit a film.
[0164] Desirably, other components such as a film thickness monitor
(quartz resonator) and a shutter are transported and placed in the
evaporation apparatus without exposed to atmosphere in the similar
manner.
[0165] In the example, the film-formation chamber is joined to a
setting chamber in which a crucible (that is filled with the
evaporation material), which has been vacuum-sealed in the
container without being exposed to atmosphere, is taken out of the
container to set the crucible in the evaporation source holder. The
crucible is transferred from the setting chamber by a transport
robot without being exposed to atmosphere. Preferably, the setting
chamber is provided with a vacuuming unit and further with a
heating unit for heating the crucible.
[0166] A mechanism of placing the first container 701 in the
film-formation chamber will be described with FIGS. 8A and 8B, the
first container is sealed in the second containers 721a and 721b
for transport.
[0167] FIG. 8A illustrates a cross section of a setting chamber 713
having a rotating table 713 for holding the second containers 721a
and 721b housing the first container, a transport mechanism for
transport the first container, and a lift mechanism 711. The
setting chamber is disposed adjacent to the film-formation chamber,
and can control atmospheres in the setting chamber by an atmosphere
control unit through the gas inlet. The transport mechanism of the
example is not limited to the configuration in which the first
container is clamped (picked) above the first container 701 for
transport as shown in FIG. 8B. The configuration is acceptable that
the first container is clamped from the side faces for
transport.
[0168] In this setting chamber, the second container is placed on
the rotating table 713 with the fastener 702 removed. The inside is
in a vacuum state, and thus the second container is not off when
the fastener 702 is removed. Then, the atmosphere control unit
reduces the pressure in the setting chamber. When the pressure in
the setting chamber becomes equal to the pressure in the second
container, the second container is easily opened. The lift
mechanism 711 removes the upper part 721a of the second container,
and the rotating table 713 rotates about a rotating shaft 712 as an
axis, which moves the lower part of the second container and the
first container. Then, the transport mechanism transfers the first
container 701 to the film-formation chamber, and places the first
container 701 in the evaporation source holder (not shown).
[0169] After that, a heating unit disposed in the evaporation
source holder sublimates the evaporation material to start
deposition. In this deposition, when the shutter (not shown)
disposed in the evaporation source holder is opened, the sublimated
evaporation material flies in the direction of the substrate to be
deposited over the substrate, and a light emitting layer (including
a hole transport layer, a hole injection layer, an electron
transport layer and an electron injection layer) is deposited.
[0170] Subsequently, after completing evaporation, the first
container is picked up from the evaporation source holder,
transported to the setting chamber, placed on the lower container
of the second container (not shown) set on the rotating table 713,
and sealed with the upper container 721a. At this time, preferably,
the first container, the upper container and the lower container
are sealed in accordance with the transferred combinations. In this
state, the setting chamber 805 is set at an atmospheric pressure.
The second container is taken out of the setting chamber, fixed
with the fastener 702, and transported to the material
manufacturer.
[0171] FIGS. 9A and 9B show an example of the setting chamber that
can hold a plurality of first containers 911. In FIG. 9A, a setting
chamber 905 has a rotating table 907 capable of holding a plurality
of the first containers 911 or second containers 912, a transport
mechanism 902b for transferring the first container, and a lift
mechanism 902a. The film-formation chamber 906 has an evaporation
source holder 903 and a holder moving mechanism (not shown here).
FIG. 9A shows a top view, and FIG. 9B shows a perspective view
inside the setting chamber. The setting chamber 905 is provided
with a gate valve 900 adjacent to the film-formation chamber 906,
and atmospheres of the setting chamber can be controlled by an
atmosphere control unit through a gas inlet. Not shown in the
drawing, the places to arrange the removed upper part (second
container) 912 are disposed separately.
[0172] Alternatively, it is acceptable that a robot is equipped in
the pretreatment chamber (setting chamber) joined to the
film-formation chamber, moved from the film-formation chamber to
the pretreatment chamber at every evaporation source, and allowed
to set evaporation materials in the evaporation source in the
pretreatment chamber. More specifically, a fabrication system is
acceptable in which the evaporation source is moved to the
pretreatment chamber. Accordingly, the evaporation source can be
set with the cleanness of the film-formation chamber
maintained.
[0173] The example can be combined freely with any one of the
embodiment and the examples 1 to 5.
Example 7
[0174] In this example, FIG. 10 shows an example of a fabrication
system of a multi-chamber system with the fully automated process
steps from first electrode formation to encapsulation.
[0175] FIG. 10 is a multi-chamber fabrication system having gates
500a to 500y, transport chambers 502, 504a, 508, 514 and 518,
delivery chambers 505, 507 and 511, preparation chamber 501, a
first film-formation chamber 506H, a second film-formation chamber
506B, a third film-formation chamber 506G, a fourth film-formation
chamber 506R, a film-formation chamber 506E, other film-formation
chambers 509, 510, 512, 513, 531 and 532, setting chambers 526R,
526G, 526B, 526E and 526H for setting evaporation sources,
pretreatment chambers 503a and 503b, an encapsulation chamber 516,
a mask stock chamber 524, an encapsulation substrate stock chamber
530, cassette chambers 520a and 520b, a tray mounting stage 521,
and a take-out chamber 519. The transport chamber 504a is provided
with a transport mechanism 504b for transferring a substrate 504c,
and the other transport chambers are similarly provided with
separate transport mechanisms as well.
[0176] Hereafter, the procedures are shown that a substrate formed
with an anode (first electrode) and an insulator (barrier wall) for
covering the end parts of the anode beforehand is carried in the
fabrication system shown in FIG. 10 to fabricate a light emitting
device. In the case of fabricating an active matrix light emitting
device, the substrate is formed with a plurality of thin film
transistors (current controlling TFTs) connected to the anode and
other thin film transistors (such as switching TFTs) beforehand,
and formed with a drive circuit formed of thin film transistors as
well. Also in the case of fabricating a simple matrix light
emitting device, it can be fabricated by the fabrication system
shown in FIG. 10.
[0177] First, the substrate is set in the cassette chamber 520a or
the cassette chamber 520b. When the substrate is a large-sized
substrate (300 mm.times.360 mm, for example), it is set in the
cassette chamber 520b. When the substrate is a general substrate
(127 mm.times.127 mm, for example), it is set in the cassette
chamber 520a, and transferred to the tray mounting stage 521. A
plurality of the substrates is set on a tray (300 mm.times.360 mm,
for example).
[0178] The substrate (the substrate formed with the anode and the
insulator for covering the end parts of the anode) set in the
cassette chamber is transferred to the transport chamber 518.
[0179] Before the substrate is set in the cassette chamber, the
surface of the first electrode (anode) is preferably cleaned with a
porous sponge immersed with a surface active agent (alkalescence)
(typically, the sponge is made of PVA (poly-vinyl alcohol) and
nylon) to remove dust and dirt on the surface in order to reduce
dot defects. As a cleaning mechanism, it is acceptable to use a
cleaning apparatus having a rotating brush (made of PVA) that
rotates about the axis in parallel to the substrate surface to
contact the substrate surface, or a cleaning apparatus having a
disc brush (made of PVA) that rotates about the axis orthogonal to
the substrate surface to contact the substrate surface. Before a
film containing organic compounds is deposited, the substrate is
preferably annealed for deacration in a vacuum in order to remove
moisture and other gasses contained in the substrate. It is fine to
transfer the substrate to a baking chamber 523 joined to the
transport chamber 518 for annealing.
[0180] Subsequently, the substrate is transferred from the
transport chamber 518 provided with a substrate transport mechanism
to the preparation chamber 501. In the fabrication system of the
example, a robot equipped in the transport chamber 518 can reverse
the substrate, which can transfer the substrate in reverse to the
preparation chamber 501. In the example, the transport chamber 518
is always kept at an atmospheric pressure. The preparation chamber
501 is joined to a vacuum processing chamber, which is preferably
vacuumed, introduced with an inert gas, and kept at an atmospheric
pressure.
[0181] Subsequently, the substrate is transferred to the transport
chamber 502 joined to the preparation chamber 501. The transport
chamber 502 is preferably vacuumed to keep in a vacuum beforehand
so as not to exist moisture and oxygen as little as possible.
[0182] As the vacuum processing chamber, a magnetic levitated
turbo-molecular pump, a cryopump or a dry-sealed vacuum pump is
provided. Accordingly, the ultimate vacuum in the transport chamber
joined to the preparation chamber can be set at 10.sup.-5 to
10.sup.-6 Pa, and the back diffusion of impurities from the pump
side and an exhaust system can be controlled. In order to prevent
impurities from being mixed in the apparatus, an inert gas such as
nitrogen and a rare gas is used for the gas to be introduced. The
gases to be introduced into the apparatus are highly purified by a
gas purifier before introduced into the apparatus. Therefore, the
gas purifier needs to be provided so that gases are highly purified
and then introduced into the evaporation apparatus. Accordingly,
oxygen, moisture and other impurities contained in the gases can be
removed beforehand. Thus, these impurities can be prevented from
being introduced into the apparatus.
[0183] In the case of removing a film containing organic compounds
having been deposited in an unnecessary place, it is fine that the
substrate is transferred to the pretreatment chamber 503a to
selectively remove a multilayer of organic compound films. The
pretreatment chamber 503a has a plasma generating unit that excites
one kind or a plurality of kinds of gases selected from Ar, H, F
and O to generate plasma for dry etching. A mask is used to
selectively remove only an unnecessary portion. It is acceptable to
provide an ultraviolet ray irradiation mechanism in the
pretreatment chamber 503a in order to irradiate ultraviolet rays as
anode surface processing.
[0184] In order to eliminate shrinks, the substrate is preferably
heated under vacuum right before the film containing organic
compounds is deposited. In order to thoroughly remove moisture and
other gases contained in the substrate in the pretreatment chamber
503b, the substrate is annealed for deaeration in a vacuum
(5.times.10.sup.-3 Torrs (0.665 Pa) or below, preferably 10.sup.-4
to 10.sup.-6 Pa). In the pretreatment chamber 503b, a flat heater
(typically, it is a sheath heater) is used to heat a plurality of
substrates uniformly. A plurality of the flat heaters can be
disposed to heat the substrate from both sides as sandwiched by the
flat heaters. Of course, the flat heater can heat the substrate
from one side. Particularly, when an organic resin film is used as
a material for an interlayer dielectric or a barrier wall, some
organic resin materials tend to absorb moisture to likely to cause
further deaeration. Thus, it is effective to perform heating under
vacuum in which the substrate is annealed at temperatures of 100 to
250.degree. C., preferably 150 to 200.degree. C. for 30 minutes or
more, and then naturally cooled for 30 minutes, for example, to
remove absorbed moisture before the layer containing organic
compounds is deposited.
[0185] Then, after heating under vacuum, the substrate is
transferred from the transport chamber 502 to the delivery chamber
505, and the substrate is further transferred from the delivery
chamber 505 to the transport chamber 504a without being exposed to
atmosphere.
[0186] Subsequently, the substrate is properly transferred to the
film-formation chambers 506R, 506G, 506B and 506E joined to the
transport chamber 504a to appropriately deposit thereon an organic
compound layer made of low weight molecules to be a hole injection
layer, a hole transport layer, a light emitting layer, an electron
transport layer, or an electron injection layer. Alternatively, the
substrate can be transferred from the transport chamber 102 to the
film-formation chamber 506H for evaporation.
[0187] Alternatively, it is acceptable that a hole injection layer
made of polymer material is deposited in the film-formation chamber
512 under atmospheric pressure or reduced pressure by ink-jet
deposition or spin coating. Also, it is fine that the substrate is
placed vertically for deposition in a vacuum by ink-jet deposition.
It is acceptable to coat
poly(styrenesulfonate)/poly(ethylenedioxythiophene) (PEDOT/PSS)
aqueous solution, polyaniline/camphor sulfonic acid aqueous
solution (PANI/CSA), PTPDES, Et-PTPDEK, or PPBA, which function as
a hole injection layer (anode buffer layer), over throughout the
surface of the first electrode (anode) for baking. In baking, the
substrate is baked in the baking chamber 523. When the hole
injection layer made of a polymer material is deposited by a
coating method using spin coating, the flatness is enhanced and the
coverage and film thickness uniformity of the deposited film
thereon can be excellent. Particularly, the film thickness of the
light emitting layer becomes uniform, and thus uniform light
emission can be obtained. In this case, preferably, the hole
injection layer is deposited by the coating method, and then the
substrate is heated under vacuum (100 to 200.degree. C.) right
before deposition by the evaporation method. It is fine that the
substrate is heated under vacuum in the pretreatment chamber 503b.
For example, the surface of the first electrode (anode) is cleaned
with sponge, and the substrate is transferred to the cassette
chamber and the film-formation chamber 512 to coat
poly(styrenesulfonate)/poly (ethylenedioxythiophene) (PEDOT/PSS)
aqueous solution over throughout the surface in a film thickness 60
nm by spin coating. Then, the substrate is transferred to the
baking chamber 523 for pre-baking at a temperature of 80.degree. C.
for ten minutes, and for baking at a temperature of 200.degree. C.
for one hour. The substrate is further transferred to the
pretreatment chamber 503b to be heated under vacuum (at a
temperature of 170.degree. C. for 30 minutes in heating, and for 30
minutes in cooling) right before evaporation. Then, the substrate
is transferred to the film-formation chambers 506R, 506G and 506B
for depositing the light emitting layer by the evaporation method
without being exposed to atmosphere. Particularly, when an ITO film
is used as an anode material and dips and bumps or fine particles
exist on the surface, the film thickness of PEDOT/PSS is formed to
be 30 nm or greater. Consequently, the influences can be
reduced.
[0188] PEDOT/PSS does not have a good wetting property when it is
coated over the ITO film. Therefore, preferably, the PEDOT/PSS
solution is coated by spin coating for a fist time, the surface is
washed with pure water to enhance the wetting property, the
PEDOT/PSS solution is again coated by spin coating for a second
time, and the substrate is baked for deposition excellent in
uniformity. After first time coating, the surface is washed with
pure water to improve the surface, which can obtain an advantage to
remove fine particles as well.
[0189] When PEDOT/PSS is deposited by spin coating, it is deposited
over throughout the surface. Therefore, it is preferably removed
selectively in the end faces, the rim part and the terminal part of
the substrate and the connection areas of the cathode to lower
wiring lines. Preferably, it is selectively removed in the
pretreatment chamber 503a with a mask by O.sub.2 ashing.
[0190] Here, the film-formation chambers 506R, 506G, 506B, 506E and
506H will be described.
[0191] Each of the film-formation chambers 506R, 506G, 506B, 506E
and 506H is equipped with movable evaporation source holders. A
plurality of the evaporation source holders is prepared to have a
plurality of containers (crucibles) appropriately sealed with EL
materials, and the holders are placed in the film-formation chamber
in this state. In the film-formation chambers, the substrate is set
in face down, and a CCD is used to align the position of the mask
for evaporation by resistance heating, which allows selective
deposition. The mask is stored in the mask stock chamber 524, and
is properly transferred to the film-formation chamber in
evaporation. The mask stock chamber is empty in evaporation, and
thus the substrate after deposited or processed can be stored. The
film-formation chamber 532 is a spare film-formation chamber for
forming a layer containing organic compounds or a metal material
layer.
[0192] Preferably, a fabrication system shown below is used to
place EL materials in the film-formation chambers. More
specifically, a container (typically, a crucible) in which an EL
material is housed by a material manufacturer beforehand is
preferably used for deposition. More preferably, the crucible is
placed without being exposed to atmosphere. Preferably, the
crucible is brought into the film-formation chamber as it is sealed
in the second container when transported from the material
manufacturer. Desirably, the setting chambers 526R, 526G, 526B,
526H and 526E are set in a vacuum or an inert gas atmosphere, the
crucible is taken out of the second container in the setting
chamber, and the crucible is placed in the film-formation chamber.
The setting chambers have a vacuuming unit, which are joined to the
film-formation chambers 506R, 506G, 506B, 506H and 506E,
respectively. FIGS. 8A and 8B, or FIGS. 9A and 9B show one example
of the setting chamber. Accordingly, the crucible and the EL
material housed in the crucible can be prevented from
contamination. In the setting chambers 526R, 526G, 526B, 526H and
526E, metal masks can be stored.
[0193] The EL materials placed in the film-formation chambers 506R,
506G, 506B, 506H and 506E are properly selected, and thus a light
emitting element showing light emission in monochrome
(specifically, white color) or full color (specifically, red green
and blue) by the whole light emitting elements can be fabricated.
For example, when a green light emitting element is fabricated, a
hole transport layer or a hole injection layer is layered in the
film-formation chamber 506H, a light emitting layer (G) is layered
in the film-formation chamber 506G, an electron transport layer or
an electron injection layer is layered in the film-formation
chamber 506E, and then a cathode is formed. Consequently, the green
light emitting element can be obtained. For example, when a full
color light emitting element is fabricated, a mask for red color is
used in the film-formation chamber 506R to sequentially layer a
hole transport layer or a hole injection layer, a light emitting
layer (R), and an electron transport layer or an electron injection
layer. A mask for green color is used in the film-formation chamber
506G to sequentially layer a hole transport layer or a hole
injection layer, a light emitting layer (G), and an electron
transport layer or an electron injection layer. A mask for blue
color is used in the film-formation chamber 506B to sequentially
layer a hole transport layer or a hole injection layer, a light
emitting layer (B), and an electron transport layer or an electron
injection layer, and then a cathode is formed. Consequently, the
full color light emitting element can be obtained.
[0194] The organic compound layer showing light emission in white
color is mainly classified into a three band type having three
primary colors, red, green and blue, and a two band type using the
relationship of complementary colors, blue/yellow or cyan/orange in
the case of layering light emitting layers having different
emission colors. It is possible to fabricate the white light
emitting element in a single film-formation chamber. For example,
when the three band type is used to obtain the white light emitting
element, film-formation chambers provided with a plurality of
evaporation source holders mounted with a plurality of crucibles
are prepared. Aromatic diamine (TPD) is sealed in a first
evaporation source holder, p-EtTAZ is sealed in a second
evaporation source holder, Alq.sub.3 is sealed in a third
evaporation source holder, an EL material of Alq.sub.3 added with
Nile Red constituting red light emission dye is sealed in a fourth
evaporation source holder, and Alq.sub.3 is sealed in a fifth
evaporation source holder. In this state, the holders are placed in
the separate film-formation chambers. Then, the first to fifth
evaporation source holders sequentially start to move, and the
substrate undergoes evaporation for layering. More specifically,
TPD is sublimed from the first evaporation source holder by heating
and deposited over throughout the substrate surface. Then, p-EtTAZ
is sublimated from the second evaporation source holder, Alq.sub.3
is sublimated from the third evaporation source holder,
Alq.sub.3:Nile Red is sublimated from the fourth evaporation source
holder, Alq.sub.3 is sublimated from the fifth evaporation source
holder, and they are deposited over throughout the substrate
surface. After that, a cathode is formed, and then the white light
emitting element can be obtained.
[0195] According to the process steps, the layers containing
organic compounds are properly layered, and then the substrate is
transferred from the transport chamber 504a to the delivery chamber
507. The substrate is further transferred from the delivery chamber
507 to the transport chamber 508 without being exposed to
atmosphere.
[0196] Subsequently, a transport mechanism equipped in the
transport chamber 508 transfers the substrate to the film-formation
chamber 510, and a cathode is formed. The cathode is an inorganic
film formed by the evaporation method using resistance heating (a
film formed by coevaporation of aluminum and an alloy such as MgAg,
MgIn, CaF.sub.2, LiF and CaN or an element in the Group 1 or the
Group 2 of the periodic table, or a multilayer film of these).
Alternatively, it is acceptable to form the cathode by
sputtering.
[0197] When a top emission light emitting device is fabricated, the
cathode is preferably transparent or semitransparent. Preferably, a
thin film made of the metal films (1 to 10 nm), or a multilayer of
the thin film made of the metal films (1 to 10 nm) and a
transparent conductive film is formed to be the cathode. In this
case, it is fine to deposit a transparent conductive film (ITO
(indium tin oxide alloy), indium oxide-zinc oxide alloy
(In.sub.2O.sub.3--ZnO), and zinc oxide (ZnO)) in the film-formation
chamber 509 by sputtering.
[0198] According to the process steps, the light emitting element
of the multilayer structure is fabricated.
[0199] It is acceptable that the substrate is transferred to the
film-formation chamber 513 joined to the transport chamber 508 and
a protection film formed of a silicon nitride film or a silicon
nitride oxide film is formed for encapsulation. Here, inside the
film-formation chamber 513, a target made of silicon, a target made
of silicon oxide, or a target made of silicon nitride is provided.
For example, the target made of silicon is used, and the atmosphere
in the film-formation chamber is set in a nitrogen atmosphere or an
atmosphere containing nitrogen and argon. Thus, a silicon nitride
film can be deposited over the cathode. Alternatively, it is fine
to deposit a thin film having a main component of carbon (a DLC
film, a CN film, and an amorphous carbon film) as the protection
film. It is also acceptable to separately provide a film-formation
chamber by CVD. The diamond like carbon film (it is also called a
DLC film) can be deposited by plasma CVD (typically, RF plasma CVD,
microwave CVD, electron cyclotron resonance (ECR) CVD, and
hot-filament CVD), flame combustion techniques, sputtering, ion
beam evaporation, and laser evaporation. For reaction gases used
for deposition, hydrogen gas and hydrocarbon based gas (CH.sub.4,
C.sub.2H.sub.2 and C.sub.6H.sub.6, for example) are used, they are
ionized by glow discharge, and ions are accelerated and collided to
the cathode negatively self biased for deposition. For the CN film,
it is fine to use C.sub.2H.sub.4 gas and N.sub.2 gas as reaction
gases for deposition. The DLC film and the CN film are insulating
films transparent or semitransparent to visible lights. Being
transparent to visible lights is that the transmittance of visible
lights ranges from 80 to 100%, and being semitransparent to visible
lights is that the transmittance of visible lights ranges from 50
to 80%.
[0200] In the example, a protection layer formed of a multilayer of
a first inorganic insulating film, a stress relaxation film, and a
second inorganic insulating film is formed over the cathode. For
example, after the cathode is formed, the substrate is transferred
to the film-formation chamber 513 to deposit the first inorganic
insulating film, and the substrate is transferred to the
film-formation chamber 532 to deposit the stress relaxation film (a
layer containing organic compounds) having water absorption and
transparency by the evaporation method. The substrate is again
transferred to the film-formation chamber 513 to deposit the second
inorganic insulating film.
[0201] Subsequently, the substrate formed with the light emitting
element is transferred from the transport chamber 508 to the
delivery chamber 511, and from the delivery chamber 511 to the
transport chamber 514 without being exposed to atmosphere. Then,
the substrate formed with the light emitting element is transferred
from the transport chamber 514 to the encapsulation chamber
516.
[0202] An encapsulation substrate is set in the loading chamber 517
from outside for preparation. In order to remove impurities such as
moisture, the substrate is preferably annealed in a vacuum
beforehand. Then, when a sealing material for bonding the substrate
formed with the light emitting element is formed on the
encapsulation substrate, the sealing material is formed in the
sealing chamber 527, and the encapsulation substrate formed with
the sealing material is transferred to the encapsulation substrate
stock chamber 530. It is acceptable that a desiccant is disposed in
the encapsulation substrate in the sealing chamber 527. Here, the
example of forming the sealing material on the encapsulation
substrate was shown, which is not defined particularly. It is
acceptable to form the sealing material on the substrate formed
with the light emitting element.
[0203] After that, the substrate is bonded to the encapsulation
substrate in the encapsulation chamber 516, and ultraviolet rays
are irradiated onto a set of the bonded substrates by an
ultraviolet ray irradiation mechanism equipped in the encapsulation
chamber 516 to cure the sealing material. Here, a UV curable resin
is used as the sealing material, which is not limited particularly
as long as it is an adhesive.
[0204] Subsequently, the set of the bonded substrates is
transferred from the encapsulation chamber 516 to the transport
chamber 514, and from the transport chamber 514 to the take-out
chamber 519, and it is taken out.
[0205] As described above, the use of the fabrication system shown
in FIG. 10 completely avoids the light emitting element from being
exposed to atmosphere until it is sealed in a closed space.
Therefore, a highly reliable light emitting device can be
fabricated. In the transport chamber 514, the substrate is
transferred under atmospheric pressure, but a vacuum and a nitrogen
atmosphere at an atmospheric pressure can be repeated for removing
moisture. However, the transport chambers 502, 504a and 508 are
desirably kept in a vacuum all the time. The transport chamber 518
is always at an atmospheric pressure.
[0206] Not shown in the drawing here, a control system for
controlling operations in the separate processing chambers, a
control system for transporting the substrate among the separate
processing chambers, and a control system for controlling routes to
transfer the substrate to the separate processing chambers for
automation are equipped.
[0207] Alternatively, in the fabrication system shown in FIG. 10, a
top emission (or top and bottom emission) light emitting element
can be fabricated in which a substrate formed with a transparent
conductive film (or a metal film (TiN)) to be an anode is brought
in, a layer containing organic compounds is deposited, and a
transparent or semitransparent cathode (for example, a multilayer
of a thin metal film (Al, Ag) and a transparent conductive film) is
deposited. The top emission light emitting element is the element
that passes light through the cathode and emits light generated in
the organic compound layer.
[0208] Alternatively, in the fabrication system shown in FIG. 10, a
bottom emission light emitting element can be fabricated in which a
substrate formed with a transparent conductive film to be an anode
is brought in, a layer containing organic compounds is deposited,
and a cathode formed of a metal film (Al, Ag) is deposited. The
bottom emission light emitting element is the element that emits
light generated in the organic compound layer from the anode being
a transparent electrode toward the TFT and passes the light through
the substrate.
[0209] The example can be combined freely with the embodiment, the
example 1, 2, 3, 5, or 6.
[0210] The deposition apparatus of the invention is used for
evaporation, which can significantly improve the film thickness
uniformity, the utilization efficiency for evaporation materials,
and throughput.
* * * * *