U.S. patent application number 10/617765 was filed with the patent office on 2004-03-04 for manufacturing apparatus.
This patent application is currently assigned to Semiconductor Energy Laboratory Co., Ltd.. Invention is credited to Murakami, Masakazu, Yamazaki, Shunpei.
Application Number | 20040040504 10/617765 |
Document ID | / |
Family ID | 31972372 |
Filed Date | 2004-03-04 |
United States Patent
Application |
20040040504 |
Kind Code |
A1 |
Yamazaki, Shunpei ; et
al. |
March 4, 2004 |
Manufacturing apparatus
Abstract
The present invention provides an evaporation apparatus, which
is one type of film formation apparatus and provides superior
uniformity in EL layer film thickness, superior throughput, and
improved utilization efficiency of EL materials and an evaporation
method. The present invention is characterized in that an
evaporation source holder, in which a container that encloses an
evaporation material is disposed, is moved at a certain pitch with
respect to a substrate during evaporation. Further, a film
thickness monitor is integrated with the evaporation source holder
for the movement. Furthermore, film thickness can be made uniform
by adjusting the moving speed of the evaporation source holder in
accordance with values measured by the film thickness monitor.
Inventors: |
Yamazaki, Shunpei; (Tokyo,
JP) ; Murakami, Masakazu; (Atsugi, JP) |
Correspondence
Address: |
NIXON PEABODY, LLP
401 9TH STREET, NW
SUITE 900
WASINGTON
DC
20004-2128
US
|
Assignee: |
Semiconductor Energy Laboratory
Co., Ltd.
Atsugi-shi
JP
|
Family ID: |
31972372 |
Appl. No.: |
10/617765 |
Filed: |
July 14, 2003 |
Current U.S.
Class: |
118/715 ;
156/345.32 |
Current CPC
Class: |
H01L 21/67184 20130101;
H01L 51/0004 20130101; H01L 51/56 20130101; C23C 14/568 20130101;
H01L 51/001 20130101; C23C 14/042 20130101; H01L 21/67253 20130101;
H01L 21/67236 20130101; H01L 21/67167 20130101; H01L 21/67745
20130101; H01L 21/67161 20130101; C23C 14/243 20130101 |
Class at
Publication: |
118/715 ;
156/345.32 |
International
Class: |
H01L 021/306 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 1, 2002 |
JP |
2002-224760 |
Claims
What is claimed is:
1. A manufacturing apparatus comprising: a loading chamber; a
transporting chamber coupled to the loading chamber; a plurality of
film formation chambers coupled to the transporting chamber; a
processing chamber coupled to the transporting chamber; wherein
each of the plurality of film formation chambers is coupled to a
vacuum evacuation processing chamber for making the inside of the
film formation chamber vacuum; wherein each of the plurality of
film formation chambers comprises: an alignment means for
performing a position alignment of a mask and a substrate; a
substrate holding means; an evaporation source holder; and a means
for moving the evaporation source holder; wherein the evaporation
source holder comprises: a container that seals an evaporation
material; a means for heating the container; and a shutter formed
over the container; wherein the processing chamber is coupled to a
vacuum evacuation processing chamber for providing a vacuum state,
wherein a plurality of plate heaters are disposed within the
processing chamber so as to overlap and open gaps therebetween, and
wherein the processing chamber can perform vacuum heating on a
plurality of substrates.
2. A manufacturing apparatus according to claim 1, wherein a means
for moving the evaporation source holder functions to move the
evaporation source holder in an x-axis direction at a certain
pitch, and functions to move the evaporation source holder in a
y-axis direction at a certain pitch.
3. A manufacturing apparatus according to claim 1, wherein the
evaporation source holder is rotated when switching between the
x-axis direction and the y-axis direction.
4. A manufacturing apparatus according to claim 1, wherein a hole
of an opening surface area S2, which is smaller than an opening
surface area S1 of the container, is opened in the shutter.
5. A manufacturing apparatus according to claim 1, wherein a film
thickness monitor is formed adjacent to the evaporation source
holder.
6. A manufacturing apparatus according to claim 1, wherein the
inert gas element comprises at least one selected from the group
consisting of He, Ne, Ar, Kr, and Xe.
7. A manufacturing apparatus comprising: a loading chamber; a
transporting chamber coupled to the loading chamber; a plurality of
film formation chambers coupled to the transporting chamber; a
processing chamber coupled to the transporting chamber; wherein
each of the plurality of film formation chambers is coupled to a
vacuum evacuation processing chamber for making the inside of the
film formation chamber vacuum; wherein each of the plurality of
film formation chambers comprises: an alignment means for
performing position alignment of a mask and a substrate; a
substrate holding means; an evaporation source holder; and a means
for moving the evaporation source holder; wherein the evaporation
source holder comprises: a container that seals an evaporation
material; a means for heating the container; and a shutter formed
over the container; wherein the processing chamber is coupled to a
vacuum evacuation processing chamber for providing a vacuum state,
and wherein at least one of a hydrogen gas, an oxygen gas, and an
inert gas is introduced in the processing chamber to generate a
plasma.
8. A manufacturing apparatus according to claim 7, wherein a
plurality of plate heaters are disposed in the transporting chamber
so as to overlap and open gaps therebetween and a processing
chamber capable of performing vacuum heating on a plurality of
substrates is coupled to the transporting chamber.
9. A manufacturing apparatus according to claim 7, wherein a means
for moving the evaporation source holder functions to move the
evaporation source holder in an x-axis direction at a certain
pitch, and functions to move the evaporation source holder in a
y-axis direction at a certain pitch.
10. A manufacturing apparatus according to claim 7, wherein the
evaporation source holder is rotated when switching between the
x-axis direction and the y-axis direction.
11. A manufacturing apparatus according to claim 7, wherein a hole
of an opening surface area S2, which is smaller than an opening
surface area S1 of the container, is opened in the shutter.
12. A manufacturing apparatus according to claim 7, wherein a film
thickness monitor is formed adjacent to the evaporation source
holder.
13. A manufacturing apparatus according to claim 7, wherein the
inert gas element comprises at least one selected from the group
consisting of He, Ne, Ar, Kr, and Xe.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a manufacturing method
provided with a deposition device for depositing materials which
can be deposited by evaporation (hereinafter, an evaporation
material), and a manufacturing method of a light emitting device
that has a layer containing an organic compound as a light emitting
layer with the manufacturing apparatus. Specifically, the present
invention relates to a vacuum-evaporation method and an evaporation
apparatus that conducts deposition by evaporating an evaporation
material from a plurality of evaporation sources provided to face a
substrate.
[0003] 2. Description of the Related Arts
[0004] In recent years, a research related to a light emitting
device having an EL element as a self-luminous light emitting
element has been activated. The light emitting device is referred
to as EL display or light emitting diode (LED). Since these light
emitting devices have characteristics such as rapid speed of
response that is suitable for movie display, low voltage, low power
consumption driving, or the like, they attracts an attention for a
next generation display including new generation's cellular phones
and portable information terminals (PDA).
[0005] An EL element that has a layer containing an organic
compound as a light emitting layer has a structure that an organic
compound-containing layer (hereinafter, an EL layer) is sandwiched
between an anode and a cathode. Electro luminescence is generated
in the EL layer by applying an electronic field to the anode and
the cathode. Luminescence obtained from the EL element includes
light emission in returning to a base state from singlet excitation
(fluorescence) and light emission in returning to a base state from
triplet excitation (phosphorescence).
[0006] Above EL layer has a laminated structure typified by "a hole
transporting layer, a light emitting layer, an electron
transporting layer". An EL material for forming an EL layer is
classified broadly into a low-molecular (monomer) material and
high-molecular (polymer) material. The low-molecular material is
deposited using the evaporation apparatus.
[0007] The evaporation apparatus has a substrate holder installed
on a substrate, a melting pot encapsulated an EL material, an
evaporation material, a shutter for prevention of rising an EL
material that will be sublimed, and a heater for heating an EL
material in a melting pot. Then, an EL material heated by the
heater is sublimed and deposited on a rolling substrate. At this
time, in order to deposit uniformly, the substrate and the melting
pot is necessary to have a distance therebetween at least 1 m.
[0008] According to the above-described evaporation apparatus and
the above-described vacuum evaporation method, when the EL layer is
formed by vacuum evaporation, almost all of the sublimated EL
material is adhered to an inner wall, a shutter or an adherence
preventive shield (protective plate for preventing a vacuum
evaporation material from adhering to an inner wall of a deposition
chamber) at inside of the deposition chamber of the evaporation
apparatus. Therefore, in forming the EL layer, an efficiency of
utilizing the expensive EL material is as extremely low as about 1%
or smaller and fabricating cost of a light emitting device becomes
very expensive.
[0009] Further, according to the evaporation apparatus of the
related art, in order to provide a uniform film, it is necessary to
separate a substrate from an evaporation source by an interval
equal to or larger than 1 m. Therefore, the evaporation apparatus
per se becomes large-sized, a time period required for emptying gas
from each deposition chamber of the evaporation apparatus is
prolonged and therefore, a deposition rate is retarded and
throughput is lowered. Moreover, when the substrate becomes larger,
there is the problem that the film thickness of the center part and
the margin of the substrate easily become different. Further, the
evaporation apparatus is of a structure of rotating the substrate
and therefore, there is a limit in the evaporation apparatus aiming
at a large area substrate.
[0010] Further, the EL material poses a problem of being
deteriorated by being easily oxidized by presence of oxygen or
water. However, in forming a film by an evaporation method, a
predetermined amount of an evaporation material put into a vessel
(glass bottle) is taken out and transferred to a vessel
(representatively, crucible, or evaporation boat) installed at a
position opposed to an object to be formed with a film at inside of
an evaporation apparatus stem and there is a concern that the
evaporation material is mixed with oxygen or water or an impurity
in the transferring operation.
[0011] Further, when the evaporation material is transferred from
the glass bottle to the vessel, the evaporation material is
transferred by the human hand at inside of a pretreatment chamber
of a deposition chamber provided with a glove or the like. However,
when the glove is provided at the pretreatment chamber, vacuum
cannot be constituted, the operation is carried out under
atmospheric pressure and there is a high possibility of mixing an
impurity. For example, even when the transferring operation is
carried out at inside of the pretreatment chamber subjected under a
nitrogen atmosphere, it is difficult to reduce moisture or oxygen
as less as possible. Further, although it is conceivable to use a
robot, since the evaporation material is in a powder-like shape, it
is very difficult to fabricate the robot for carrying out the
transferring operation. Therefore, it is difficult to constitute
steps of forming an EL element, that is, from a step of forming an
EL layer above a lower electrode to a step of forming an upper
electrode by an integrated closed system enabling to avoid mixing
of an impurity.
SUMMARY OF THE INVENTION
[0012] Hence, the present invention provides an evaporation
apparatus which is a manufacturing device promoting an efficiency
of utilizing an EL material and forming film excellent in
uniformity or throughput of forming an EL layer and an evaporation
method therefor. Further, the invention provides a light emitting
device fabricated by the evaporation apparatus and the evaporation
method according to the invention and a method of fabricating the
light emitting device.
[0013] Further, the invention provides a manufacturing device of
subjecting an EL material to evaporation efficiently to a large
area substrate having a substrate size of, for example, 320
mm.times.400 mm, 370 mm.times.470 mm, 550 mm.times.650 mm, 600
mm.times.720 mm, 680 mm.times.880 mm, 1000 mm.times.1200 mm, 1100
mm.times.1250 mm or 1150 mm.times.1300 mm. The present invention
also provides an evaporation apparatus that can obtain uniform film
thickness for a large area substrate in its whole surface.
[0014] Further, the invention provides a fabricating device capable
of avoiding an impurity from mixing to an EL material.
[0015] The present invention provides an evaporation apparatus
having such a feature that a substrate and an evaporation source
move relative to each other in order to attain the aforementioned
objectives. That is, the present invention has a feature in that an
evaporation source holder, on which a container 501 that encloses
an evaporation material is disposed, moves at a pitch with respect
to the substrate in the evaporation apparatus. Further, a film
thickness monitor is integrated with the evaporation source holder
to be moved. Further, the moving speed of the evaporation source
holder is controlled in accordance with values measured by the film
thickness monitor to obtain uniform film thickness.
[0016] Further, as shown by an example thereof in FIG. 3,
evaporation speed can always be measured, even in a state in which
a shutter 503 is closed, by opening a minute hole in the shutter
503, thus making an evaporation material emitted obliquely from the
hole (opening portion S2) strike the film thickness monitor. Note
that there are no limitations placed on the method used for opening
and closing the shutter. A sliding shutter may also be used. The
container 501 that encloses the evaporation material is heated and
left in a heated state during evaporation. Even if there is no
substrate above the evaporation source holder 502 after the
movement thereof, heating is still performed. Therefore, by using
the shutter 503, waste of the evaporation material can be
eliminated. Further, the minute hole is formed in the shutter, so a
leak can be formed in the container so that the pressure within the
container may be prevented from becoming high pressure. Note that
an opening surface area S2 of the hole is made smaller than an
opening portion surface area S1 of the container.
[0017] Further, it is preferable that the evaporation source holder
be rotated at a substrate circumferential portion in order to make
the film thickness uniform. An example of the evaporation source
holder rotating is shown in FIG. 2C. Further, half-rotation may
also be repeatedly performed as shown in FIG. 2D. It is preferable
to move the evaporation source holder at a certain pitch so that
sublimated edges (hems) of the evaporation material are made to
overlap.
[0018] Further, the main cause of shrinkage, whereby a non-light
emitting region expands, is that a minute amount of moisture, which
includes adsorbed moisture, reaches a layer that contains an
organic compound. It is therefore desirable to remove the moisture
(including adsorbed moisture) residing within an active matrix
substrate provided with a TFT immediately before forming the layer
that contains the organic compound on the active matrix
substrate.
[0019] The present invention can prevent or reduce the development
of shrinkage by providing a heat treatment chamber for uniformly
heating a plurality of substrates, and performing vacuum heating at
temperature of 100.degree. C. to 250.degree. C. before forming the
organic compound containing layer using a plurality of plate
heaters (typically, sheath heater). In particular, moisture is
easily adsorbed by organic resin materials when such materials are
used as an interlayer insulating film or partition material, and in
addition, there is a fear in that degassing will develop.
Therefore, it is effective to perform vacuum heating at the
temperature of 100.degree. C. to 250.degree. C. before forming the
organic compound containing layer.
[0020] In addition, according to the present invention, it is
preferable that steps from forming the organic compound containing
layer through sealing be performed without exposure to the ambient
atmosphere in order to prevent moisture from penetrating to the
organic compound containing layer.
[0021] According to an aspect of the invention disclosed in this
specification, it is characterized in that a manufacturing
apparatus includes:
[0022] a loading chamber;
[0023] a transporting chamber coupled to the loading chamber;
[0024] a plurality of film formation chambers coupled to the
transporting chamber;
[0025] a processing chamber coupled to the transporting
chamber;
[0026] wherein each of the plurality of film formation chambers is
coupled to a vacuum evacuation processing chamber for making the
inside of the film formation chamber vacuum;
[0027] wherein each of the plurality of film formation chambers
includes:
[0028] alignment means for performing position alignment of a mask
and a substrate;
[0029] substrate holding means;
[0030] an evaporation source holder; and
[0031] means for moving the evaporation source holder;
[0032] wherein the evaporation source holder includes:
[0033] a container that seals an evaporation material;
[0034] means for heating the container; and
[0035] a shutter formed over the container;
[0036] wherein the processing chamber is coupled to a vacuum
evacuation processing chamber for providing a vacuum state;
[0037] wherein a plurality of plate heaters are disposed in the
processing chamber so as to overlap and open gaps therebetween;
and
[0038] wherein the processing chamber can perform vacuum heating on
a plurality of substrates.
[0039] Further, it is preferable to perform plasma processing
before evaporation of a layer that contains an organic compound in
order to remove organic substances and moisture.
[0040] According to another aspect of the present invention, it is
characterized in that a manufacturing apparatus includes:
[0041] a loading chamber;
[0042] a transporting chamber coupled to the loading chamber;
[0043] a plurality of film formation chambers coupled to the
transporting chamber;
[0044] a processing chamber coupled to the transporting
chamber;
[0045] wherein each of the plurality of film formation chambers is
coupled to a vacuum evacuation processing chamber for making the
inside of the film formation chamber vacuum;
[0046] wherein each of the plurality of film formation chambers
includes:
[0047] alignment means for performing position alignment of a mask
and a substrate;
[0048] substrate holding means;
[0049] an evaporation source holder; and
[0050] means for moving the evaporation source holder;
[0051] wherein the evaporation source holder includes:
[0052] a container that seals an evaporation material;
[0053] means for heating the container; and
[0054] a shutter formed over the container;
[0055] wherein the processing chamber is coupled to a vacuum
evacuation processing chamber for providing a vacuum state; and
[0056] wherein hydrogen gas, oxygen gas, or an inert gas is
introduced in the processing chamber to generate a plasma.
[0057] In the structure described above, the apparatus is
characterized in that a plurality of plate heaters are disposed in
the transporting chamber so as to overlap and open gaps
therebetween and a processing chamber capable of performing vacuum
heating on a plurality of substrates is coupled to the transporting
chamber. Uniformly performing vacuum heating on the substrates and
removing adsorbed moisture from the substrates using the plate
heaters can prevent or reduce the development of shrinkage.
[0058] Further, the means for moving the evaporation source holder
in each of the structures described above functions to move the
evaporation source holder in an x-axis direction at a certain
pitch, and functions to move the evaporation source holder in a
y-axis direction at a certain pitch. Substrate rotation is not
necessary in an evaporation method of the present invention, and
therefore an evaporation apparatus capable of handling large
surface area substrates can be provided. Further, it becomes
possible to form evaporated films uniformly in accordance with the
present invention, in which the evaporation source holder moves
with respect to the substrates in the x-axis direction and in the
y-axis direction.
[0059] In the evaporation apparatus of the present invention, a gap
distance d between the substrates and the evaporation source holder
during evaporation is shortened to, typically equal to or less than
30 cm, preferably equal to or less than 20 cm, more preferably from
5 cm to 15 cm. The utilization efficiency of the evaporation
material as well as throughput is thus markedly improved.
[0060] The evaporation source holder in the evaporation apparatus
described above includes: a container (typically a crucible); a
heater provided on the outside of the container, through a soaking
member; a heat insulating layer formed on the outside of the
heater; an outer casing in which the aforementioned elements are
received; a cooling pipe wound around the outside of the outer
casing; an evaporation shutter that opens and closes an opening
portion of the outer casing including an opening portion of a
crucible; and a film thickness sensor. Note that a container
capable of being transported in a state with the heater fixed to
the container may also be used. Further, the container is one
capable of withstanding high temperature, high pressure, and low
pressure, and is made by using a material such as sintered boron
nitride (BN), a sintered compound of boron nitride (BN) and
aluminum nitride (AIN), quartz, or graphite.
[0061] Further, a mechanism capable of moving the evaporation
source holder within the film formation chamber in the x-direction
and in the y-direction, with the evaporation source holder
maintained in a horizontal attitude, is provided. The evaporation
source holder is moved in a zigzag manner here, as shown in the
planar plane of the evaporation source holder in FIG. 2A and FIG.
2B. Further, the movement pitch used for the evaporation source
holder may be suitably adjusted to the partition spacing.
[0062] Note that the timing at which evaporation source holders A,
B, C, and D begin to move may be after movement of the previous
evaporation source holder has stopped, and may also be before
movement of the previous evaporation source holder has stopped, in
FIG. 2A and FIG. 2B. For example, if an organic material having
hole transporting characteristics is set into the evaporation
source holder A, an organic material that becomes a light emitting
layer is set in the evaporation source holder B, an organic
material having electron transporting characteristics is set in the
evaporation source holder C, and a material that becomes a cathodic
buffer is set in the evaporation source holder D, then layers of
these materials can be laminated in succession in the same chamber.
Further, regions in interfaces between each film, in which the
evaporation materials are mixed (mixing region), can be formed in
an EL layer having a laminate structure provided that movement of
the next evaporation source holder begins before the current
evaporated film has solidified.
[0063] In accordance with the present invention, in which the
substrates and the evaporation source holders A, B, C, and D move
relative to each other, it is not necessary to make the distance
between the substrates and the evaporation source holders long, and
apparatus miniaturization can thus be achieved. Further, the
evaporation apparatus becomes small, and therefore the adhesion of
sublimated evaporation materials on interior walls within the film
formation chambers, or on evaporation preventing shields can be
reduced. The evaporation materials can thus be utilized without
waste. In addition, it is not necessary to rotate the substrates in
the evaporation method of the present invention, and therefore an
evaporation apparatus capable of handling large surface area
substrates can be provided. Further, it becomes possible to form
evaporated films uniformly in accordance with the present
invention, in which the evaporation source holders are moved to the
substrates in the x-direction and in the y-direction.
[0064] Further, it is not always necessary that one organic
compound or one type of organic compound be provided in the
evaporation source holders. A plurality of materials or types may
also be used. For example, in addition to one type of material
provided as a light emitting organic compound in an evaporation
source holder, a different organic compound capable of serving as a
dopant (dopant material) may also be provided. It is preferable
that an organic compound layer for evaporation be structured by a
host material, and by a light emitting material (dopant material)
having a lower excitation energy than the host material. It is also
preferable that the excitation energy of the dopant be lower than
the excitation energy of a hole transporting region and lower than
the excitation energy of an electron transporting layer. The dopant
can thus be made to effectively emit light while diffusion of the
molecular excitons of the dopant is prevented. Further, the carrier
recombination efficiency can also be increased, provided that the
dopant is a carrier trapping material. Furthermore, the addition of
a material, into a mixing region as a dopant, which is capable of
converting triplet excitation energy into luminescence, also falls
under the scope of the present invention. A concentration gradient
may also be provided in the mixing region.
[0065] In addition, it is desirable that the directions used during
evaporation be diagonal so as to intersect at the locations of the
evaporation materials if a plurality of organic compounds are
provided in one evaporation source holder, so that the organic
compounds mix with each other. Further, four evaporation materials
(for example, two types of host materials as evaporation materials
a, and two types of dopant materials as evaporation materials b)
may be provided to the evaporation source holder in order to
perform co-evaporation. Further, when pixel size is small (or when
the gap between each insulator is small), film formation can be
performed precisely by dividing an inside portion of the container
into four divisions, and performing co-evaporation by suitably
evaporating from each of the divisions.
[0066] Furthermore, the gap distance d between the substrate and
the evaporation source holder is shortened to, typically equal to
or less than 30 cm, and preferably from 5 cm to 15 cm, and
therefore there is a fear in that an evaporation mask will also be
heated. It is therefore desirable to form the evaporation mask by
using a metallic material having a low thermal expansion
coefficient, which does not tend to deform due to heat (the
following materials, for example: tungsten, tantalum, chromium,
nickel, or molybdenum, which are high melting point metals; an
alloy metal containing one of these metals; stainless steel;
Inconel; or Hastelloy). A low thermal expansion alloy of 42% nickel
and 58% iron or the like can be used, for example. Further, a
mechanism for circulating a cooling medium (cooling water or a
cooling gas) to the evaporation mask may also be provided in order
to cool the heated evaporation mask.
[0067] It is preferable to generate a plasma within the film
formation chamber by using a plasma generating means, gasify
evaporants adhering to the mask, and evacuate the gasified
evaporants to the outside of the film formation chamber in order to
clean off the evaporants adhering to the mask. A separate electrode
is therefore formed on the mask, and a high frequency electric
power source is connected to one of the electrodes. It is thus
preferable to form the mask by using a conductive material.
[0068] Note that the evaporation mask is used when selectively
forming an evaporated film on a first electrode (cathode or anode),
and is not particularly necessary if forming the evaporated film
over the entire surface.
[0069] Further, the film formation chamber has a gas introducing
means for introducing one gas, or a plurality of gasses selected
from the group consisting of Ar, H, F, NF.sub.3, and O, and a means
for evacuating the gasified evaporants. It thus becomes possible to
clean the inside of the evaporation chamber during maintenance,
without exposing it to the ambient atmosphere, in accordance with
the structure discussed above.
[0070] Further, the apparatus is characterized in that the
evaporation source holder is rotated when switching between the
x-axis direction and the y-axis direction in each of the structures
described above. The film thickness can be made uniform by rotating
the evaporation source holder.
[0071] Further, the apparatus is characterized in that the hole of
the opening surface area S2, which is smaller than the opening
surface area S1 of the container, is opened in the shutter in each
of the structures described above. Pressure within the container is
made to leak out so as not to become high pressure by forming the
minute hole in the shutter.
[0072] Further, the apparatus is characterized in that a film
thickness monitor is formed in the evaporation source holder in
each of the structures described above. The film thickness can also
be made uniform by adjusting the moving speed of the evaporation
source holder in accordance with values measured by the film
thickness monitor.
[0073] Further, the inert gas element in each of the structures
described above is one element or a plurality of elements selected
from the group consisting of He, Ne, Ar, Kr, and Xe. Of those, Ar
is inexpensive, which is therefore preferable.
[0074] Further, a process for setting an EL material into the film
formation chamber before evaporation, an evaporation process, and
the like can be considered as the main processes during which there
is a fear in that impurities such as oxygen and moisture will
contaminate the evaporated EL materials or metallic materials.
[0075] It is therefore preferable to provide a glove in a
preprocessing chamber coupled to the film formation chamber, move
the glove from the film formation chamber to the preprocessing
chamber for each evaporation source, and set the evaporation
material into the evaporation source in the preprocessing chamber.
That is, a manufacturing apparatus in which the evaporation source
is moved to the preprocessing chamber is provided. The evaporation
source can thus be set while maintaining the cleanliness level of
the film formation chamber.
[0076] Further, a brown colored glass bottle is normally used for
storing the EL material, and the bottle is closed by using a
plastic cap. The sealing level of the container in which the EL
material is stored can also be considered to be insufficient.
[0077] A predetermined amount of the evaporation material placed in
the container (glass bottle) is taken out when performing film
formation by evaporation, and transferred to a container
(typically, a crucible or evaporation boat) disposed in a position
within the evaporation apparatus that opposes an object on which a
film is to be formed. However, there is a fear in that impurities
will mix in during transfer operation. That is, there is a
possibility of contamination by an impurity such as oxygen or
moisture, which is one cause of EL element deterioration.
[0078] Performing the transfer operation from the glass bottle to
the container manually can be considered, for example, within the
preprocessing chamber, which is provided with a glove or the like.
However, a vacuum cannot be provided if the preprocessing chamber
is provided with a glove, and the operation is performed at ambient
pressure. It is therefore difficult to remove as much moisture and
oxygen within the preprocessing chamber as possible, even if the
operation is performed in a nitrogen atmosphere, for example. The
use of a robot can be considered, but the evaporation materials are
powdery, and therefore it is difficult to manufacture a robot for
transfer operation. Accordingly, it is difficult to make a
continuous closed system capable of avoiding impurity
contamination, in which complete automation is made from a step of
forming an EL layer on a lower portion electrode through a step of
forming an upper portion electrode.
[0079] The present invention is one in which the prevention of
impurity contamination into a high purity evaporation material is
achieved in a manufacturing system that stores EL materials and
metallic materials directly in prearranged containers disposed in
an evaporation apparatus, without using conventional containers,
which are typically brown color glass bottles or the like, as
containers for storing the EL materials. Further, sublimation
purification may also be performed directly in the prearranged
containers disposed in the evaporation apparatus, without dividing
and receiving the evaporation materials obtained, when the EL
material evaporation materials are received directly. The present
invention makes it possible to handle even more very highly
purified evaporation materials, which are expected in the future.
Further, the metallic materials may be received directly in the
prearranged containers disposed in the evaporation apparatus, and
evaporation may be performed by resistance heating.
[0080] Furthermore, it is also preferable to similarly transport
other components, such as the film thickness monitors (liquid
crystal oscillators or the like) and shutters, and dispose them
within the evaporation apparatus without exposure to the ambient
atmosphere.
[0081] It is desirable that a light emitting device manufacturer
who uses the evaporation apparatus entrust the work for receiving
the evaporation materials directly in the containers, which are
disposed in the evaporation apparatus, to a materials manufacturer
that manufactures and/or sells the evaporation materials.
[0082] Further, a fear of impurity contamination depends upon the
conventional transferring operation by the light emitting device
manufacturer, no matter how highly pure the EL materials supplied
by the material manufacturer are. The purity of the EL materials
cannot be maintained, and there is a limit to their purity. In
accordance with the present invention, extremely high purity EL
materials obtained by the material manufacturer can be maintained
by the light emitting device manufacturer and the material
manufacturer cooperating in an endeavor to reduce impurity
contamination. The light emitting device manufacturer can thus
perform evaporation without a reduction in the material purity.
[0083] An embodiment of a transportation container is explained in
detail using FIG. 6. A second container used for transportation and
divided into an upper portion 621a and a lower portion 621b
includes: a fixing means 706 for fixing a first container provided
in the upper portion of the second container; a spring 705 for
applying pressure to the fixing means; a gas introduction port 708
that is provided in the lower portion of the second container, and
which becomes a gas pathway for maintaining a reduced pressure in
the second container; an O-ring 707 that fixes the upper portion
container 621a and the lower portion container 621b; and a fastener
702. A first container 701, in which a purified evaporation
material is enclosed, is disposed within the second container. Note
that the second container may be formed by a material that contains
stainless steel, and the first container may be formed by a
material containing titanium.
[0084] The purified evaporation material is enclosed in the first
container 701 by the material manufacturer. The upper portion 621a
and the lower portion 621b of the second container are joined
through the O-ring 707, and the upper portion container 621a and
the lower portion container 621b are fixed by the fastener 702. The
first container 701 is thus enclosed within the second container.
The inside of the second container is then reduced in pressure
through the gas introduction portion 708, and in addition, its
atmosphere is replaced by a nitrogen atmosphere. The spring 705 is
then adjusted, and the first container 701 is fixed by the fixing
means 706. Note that a drying agent may also be disposed within the
second container. Even tiny amounts of oxygen and moisture can be
prevented from adhering to the evaporation material if the inside
of the second container is made vacuum, is reduced in pressure, or
is maintained at a nitrogen atmosphere.
[0085] The containers are transported to the light emitting device
manufacturer in this state, and the first container 701 is directly
installed into a processing chamber. Thereafter, the evaporation
material is sublimated next by heat treatment, and the formation of
an evaporated film is performed.
[0086] A mechanism for installing the first container in the film
formation chamber, which is sealed and transported in the second
container, is explained next using FIGS. 4A and 4B, and FIGS. 5A
and 5B. Note that FIGS. 4A and 4B, and FIGS. 5A and 5B are diagrams
that show the first container during transportation.
[0087] FIG. 4A shows a top view of an installation chamber 805. The
installation chamber 805 includes a table 804 on which the first
container 701 or the second container is set, an evaporation source
holder 803, and a transporting means 802 for transporting the first
container. FIG. 4B shows a perspective view of the installation
chamber. Further, the installation chamber 805 is disposed so as to
be adjacent to a film formation chamber 806. It is possible to
control the atmosphere of the installation chamber through the gas
introduction port by using a means for controlling the atmosphere.
Note that the transporting means of the present invention is not
limited to structures like the one shown in FIGS. 4A and 4B, in
which sides of the first container are sandwiched. Structures in
which the first container is sandwiched (picked up) from above the
first container may also be employed.
[0088] The second container is disposed on the table 804 in the
installation chamber 805 in a state where the fastener 702 is
released. The inside of the installation chamber 805 is then placed
into a reduced pressure state by the means for controlling the
atmosphere. The second container reaches a state at which it can be
opened when the pressure within the installation apparatus becomes
equal to the pressure within the second container. The upper
portion 621a of the second container is then removed by using the
transporting means 802, and the first container 701 is disposed on
the evaporation source holder 803. Note that, although not shown in
the figures, a location for disposing the removed upper portion
621a may be suitably provided. The evaporation source holder 803 is
then moved from the installation chamber 805 to the film formation
chamber 806.
[0089] Thereafter, the evaporation material is then sublimated by a
heating means provided in the evaporation source holder 803, and
film formation begins. When a shutter (not shown) formed in the
evaporation source holder 803 is opened during film formation, the
sublimated evaporation material will scatter toward the substrate
and deposit thereupon, thus forming a light emitting layer
(including hole transporting layers, hole injecting layers,
electron transporting layers, and electron injecting layers).
[0090] The evaporation source holder 803 is then returned to the
installation chamber 805 after evaporation is complete. The first
container 701, which is disposed in the evaporation source holder
803, is then moved to a lower portion container (not shown) of the
second container, which is disposed on the table 804, by the
transporting means 802, and is sealed by the upper portion
container 621a. It is preferable to seal the first container, the
upper portion container 621a, and the lower portion container at
this point by combining them during transportation. In this state,
the installation chamber 805 is set to ambient atmospheric
pressure, the second container is taken out from the installation
chamber, the fastener 702 is fixed, and this assembly is sent to
the material manufacturer.
[0091] A mechanism for disposing a plurality of the first
containers, which are sealed in the second container and
transported, into a plurality of the evaporation source holders is
explained next using FIGS. 5A and 5B. This mechanism differs from
that of FIGS. 4A and 4B.
[0092] FIG. 5A shows a top view of an installation chamber 905. The
installation chamber 905 includes a table 904 on which a first
container or a second container is set, a plurality of evaporation
source holders 903, a plurality of transporting means 902 for
transporting the first containers, and a rotating table 907. FIG.
5B shows a perspective view of the installation chamber 905.
Further, the installation chamber 905 is disposed so as to be
adjacent to a film formation chamber 906. It is possible to control
the atmosphere in the installation chamber through a gas
introduction port by using a means for controlling the
atmosphere.
[0093] The plurality of first containers 701 can be disposed in the
plurality of evaporation source holders 903 by using the rotating
table 907 and the plurality of transporting means 902, and the
operation for moving the plurality of first containers from the
plurality of evaporation source holders to the table 904 can be
performed with good efficiency after film formation is complete. It
is preferable to dispose the first containers in the transported
second containers at this point.
[0094] Note that the rotating table 907 may have a rotating
function in order to increase the efficiency of transporting the
evaporation source holders when evaporation is started, and the
evaporation source holders when evaporation is completed. The
rotating table 907 is not limited to the structure discussed above.
The rotating table 907 may have a function for moving horizontally,
and the plurality of first containers may be disposed in the
evaporation source holders by using a moving means 902 at the stage
when the evaporation source holders, which are disposed in the film
formation chamber 906, are approached.
[0095] Impurities can be reduced to a minimum in evaporated films
formed by an evaporation apparatus like that discussed above. High
reliability and brightness can be achieved if light emitting
elements are completed by using these types of evaporated films.
Further, containers sealed by a material manufacturer can be
installed directly into the evaporation apparatus in accordance
with this type of manufacturing system, and therefore the adherence
of oxygen and moisture on evaporation materials can be prevented.
The present invention makes it possible to handle even more very
highly purified light emitting layers in the future. Further,
material waste can be eliminated by once again purifying the
containers in which residual evaporation materials remain. In
addition, the first containers and the second containers can be
reutilized, thus lowering costs.
[0096] Further, the present invention may reduce the processing
time per single substrate. As shown in FIG. 10, a multi-chamber
manufacturing apparatus provided with a plurality of film formation
chambers has a first film formation chamber for depositing onto a
first substrate, and a second film formation chamber for depositing
onto a second substrate. A plurality of organic compound layers are
laminated concurrently (in parallel) in each of the film formation
chambers, thus reducing the processing time per single substrate.
That is, the first substrate is taken out from a transporting
chamber and placed in the first film formation chamber, and vapor
deposition on the first substrate is performed. During this time,
the second substrate is taken out from the transporting chamber and
placed in the second film formation chamber, and vapor deposition
is also performed on the second substrate.
[0097] Six film formation chambers are provided in a transporting
chamber 1004a in FIG. 10, and it is therefore possible to place six
substrates into the respective film formation chambers and perform
evaporation in order and concurrently. Further, evaporation can
also be performed during maintenance of one film formation chamber
by using the other film formation chambers, without temporarily
stopping the production line.
[0098] Further, hole transporting layers, light emitting layers,
and electron transporting layers corresponding to the colors R, G,
and B may be laminated in succession in different film formation
chambers if a full color light emitting device is being
manufactured in FIG. 10. Furthermore, the hole transporting layers,
the light emitting layers, and the electron transporting layers
corresponding to R, G, and B may also be laminated in succession in
the same film formation chamber. A film formation apparatus like
that shown in FIGS. 2A and 2B may be used if the hole transporting
layers, the light emitting layers, and the electron transporting
layers corresponding to R, G, and B are laminated in succession in
the same film formation chamber. That is, an evaporation apparatus,
in which a plurality of evaporation source holders (evaporation
source holders that move in the x-direction or the y-direction), at
least three or more, are provided in one film formation chamber,
may be employed. Note that it is preferable to use different
evaporation masks corresponding to R, G, and B in order to avoid
color mixing. It is also preferable to perform mask alignment
before vapor deposition, thus forming films only in desired
regions. The same evaporation mask may be used for R, G, and B in
order to reduce the number of masks. Mask alignment may be
performed before vapor deposition by shifting the mask position for
each color, thus forming films only in desired regions.
[0099] Further, the present invention is not limited to a structure
in which the hole transporting layer, the light emitting layer, and
the electron transporting layer are laminated in succession in the
same chamber. The hole transporting layer, the light emitting
layer, and the electron transporting layer may also be laminated in
succession in a plurality of coupled chambers.
[0100] Further, although a structure is discussed as a typical
example in the above explanation, in which three layers, a hole
transporting layer, a light emitting layer, and an electron
transporting layer, are laminated as an organic compound containing
layer and disposed between a cathode and an anode, the present
invention is not limited to this particular structure. Structures
in which a hole injecting layer, a hole transporting layer, a light
emitting layer, and an electron transporting layer are laminated in
order on an anode may also be used. In addition, structures in
which a hole injecting layer, a hole transporting layer, a light
emitting layer, an electron transporting layer, and an electron
injecting layer are laminated in order on an anode may also be
used. Further, two layer structures and single layer structures may
also be used. A fluorescent pigment or the like may also be doped
into the light emitting layer. Further, light emitting layers
having hole transporting characteristics, and light emitting layers
having electron transporting characteristics may also be used as
light emitting layers. Furthermore, the layers may all be formed by
using low molecular weight materials, and in addition, one or more
layers may be formed by using high molecular weight materials. Note
that all layers formed between a cathode and an anode are referred
to generically as an organic compound containing layer (EL layer)
in this specification. The hole injecting layers, the hole
transporting layers, the light emitting layers, the electron
transporting layers, and the electron injecting layers discussed
above are therefore all included in the category of EL layers.
Further, the organic compound containing layer (EL layer) may also
contain inorganic materials such as silicon.
[0101] Note that a light emitting layer (EL element) includes an
organic compound containing layer (hereinafter referred to as an EL
layer) in which luminescence (electroluminescence) can be obtained
by the application of an electric field, an anode, and a cathode.
As for luminescence in organic compounds, there are a light
emission when returning to a base state from a singlet excitation
state (fluorescence), and a light emission when returning to a base
state from a triplet excitation state (phosphorescence). Light
emitting devices manufactured in the present invention can apply to
both types of light emission.
[0102] Further, there are no limitations placed on a method of
driving a screen display in the light emitting device of the
present invention. For example, a dot sequential driving method, a
line sequential driving method, a screen sequential driving method,
or the like may be used. Typically, a time gray scale driving
method or an area gray scale method may be suitably applied as a
line sequential driving method. Further, image signals input to
source lines of the light emitting device may be analog signals or
digital signals. Driving circuits and the like may be suitably
designed in accordance with the image signal type.
[0103] Furthermore, light emitting elements formed by a cathode, an
EL layer, and an anode are referred to as EL elements within this
specification. There are two methods of forming the EL elements, a
method of forming EL layers between two types of stripe shape
electrodes that are formed so that they mutually intersect (simple
matrix method), and a method of forming EL layers between pixel
electrodes and opposing electrodes that are disposed in a matrix
shape and are connected to TFTs (active matrix method).
BRIEF DESCRIPTION OF THE DRAWINGS
[0104] In the accompanying drawings:
[0105] FIG. 1 is a diagram showing a manufacturing apparatus of the
present invention;
[0106] FIGS. 2A and 2B are diagrams showing movement pathways of an
evaporation source holder of the present invention, and FIGS. 2C
and 2D are diagrams of movement of evaporation source holder at
substrate circumstantial portion;
[0107] FIG. 3 is a diagram showing an evaporation source holder
(having a hole in its shutter) of the present invention;
[0108] FIGS. 4A and 4B are diagrams showing crucible transportation
to an evaporation source holder in an installation chamber;
[0109] FIGS. 5A and 5B are diagrams showing crucible transportation
to an evaporation source holder in an installation chamber;
[0110] FIG. 6 is a diagram showing a transportation container of
the present invention;
[0111] FIGS. 7A and 7B are diagrams showing the opening and closing
of a shutter on an evaporation source holder (one container);
[0112] FIGS. 8A and 8B are diagrams showing the opening and closing
of shutters on evaporation source holders (a plurality of
containers);
[0113] FIG. 9 is a diagram showing a sequence for a manufacturing
apparatus of the present invention;
[0114] FIG. 10 is a diagram showing a manufacturing apparatus of
the present invention (Embodiment 2);
[0115] FIG. 11 is a diagram showing an example of a sequence
(Embodiment 2);
[0116] FIGS. 12A and 12B are diagrams showing an example of a
sequence (Embodiment 2); and
[0117] FIG. 13 is a diagram showing a multiple-stage vacuum heating
chamber.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0118] An embodiment mode of the present invention is explained
below.
[0119] An evaporation source holder that is made to move in an
x-direction or a y-direction within a film formation chamber is
explained here using FIGS. 7A and 7B.
[0120] FIG. 7A is a diagram that shows a state in which heat
treatment is performed by a heating means 303 connected to an
electric power source 307 with a sliding shutter 306 in an open
state and an evaporation material 302 in a container 301 is made to
evaporate. Note that a film thickness monitor 305 is attached to
the evaporation source holder 304. Film thickness can be controlled
with the shutter in the open state by adjusting the heat treatment
temperature and the moving speed of the evaporation source holder
304 by the electric power source 307.
[0121] On the other hand, FIG. 7B shows the sliding shutter 306 in
a closed state. A hole is opened in the shutter 306, and a material
emitted obliquely from the hole moves in a direction toward the
film thickness monitor 305. Note that, although a gap is opened
between the container 301 and the shutter 306a in the example shown
in FIGS. 7A and 7B, the gap may be narrow, or there may be no gap
at all. That is, the container 301 and the shutter 306 may be in
intimate contact. Pressure inside the container can leak out even
if they are in intimate contact because the minute hole is
opened.
[0122] Further, although an example of the evaporation source
holder provided with one of the containers 301 is shown in FIGS. 7A
and 7B, an evaporation source holder provided with a plurality of
containers 202 in order to perform co-evaporation or the like is
shown in FIGS. 8A and 8B.
[0123] Film thickness monitors 201 are provided in each of the two
containers 202, and one of the containers is disposed with inclined
with respect to a fixed substrate 200, as shown in FIGS. 8A and 8B.
A heater is used as a heating means, and evaporation is performed
by a resistive heating method. Note that the evaporation source
holder is moved below the substrate with the shutter in an open
state during evaporation, as shown in FIG. 8A. Further, evaporation
is stopped by closing the shutter 204 having the minute hole if
there is no evaporation source holder below the substrate 200.
[0124] The evaporation source holder as described above is moved in
a zigzag manner in the film formation chamber on a planar plane, as
shown in FIG. 2A and 2B.
[0125] The incursion of moisture into layers that contain organic
compounds is prevented in a multi-chamber manufacturing apparatus
(one example is shown in FIG. 1) provided with the film formation
chamber. It is therefore possible to perform processing from the
formation of the organic compound containing layers up through
sealing operations without exposure to the ambient atmosphere.
[0126] A further detailed explanation of the present invention
having the structure described above is provided by using the
embodiments shown below.
[0127] Embodiments
[0128] [Embodiment 1]
[0129] An example of a multi-chamber manufacturing apparatus in
which manufacturing processes from a first electrode up through
sealing are automated is shown in FIG. 1 in this embodiment.
[0130] FIG. 1 is a multi-chamber manufacturing apparatus that
includes gates 100a to 100y; an extraction chamber 119;
transporting chambers 102, 104a, 108, 114, and 118; delivery
chambers 105, 107, and 111; a stocking chamber (loading chamber)
101; a first film formation chamber 106H; a second film formation
chamber 106B; a third film formation chamber 106G; a fourth film
formation chamber 106R; a fifth film formation chamber 106E; other
film formation chambers 109 (ITO or IZO film), 110 (a metal film),
112 (spin coat or ink jet), 113 (SiN film or SiOx film), 131
(sputtering chamber), and 132 (sputtering chamber); installation
chambers 126R, 126G, 126B, 126E, and 126H for disposing evaporation
sources; preprocessing chambers 103a (bake or O.sub.2 plasma,
H.sub.2 plasma, Ar plasma) and 103b (vacuum bake); a sealing
chamber 116; a mask stocking chamber 124; a sealing substrate
stocking chamber 130; cassette chambers 120a and 120b; and a tray
loading stage 121.
[0131] Procedures are shown below for placing a substrate, on which
a thin film transistor, an anode (first electrode), and an
insulator that covers edge portions of the anode are formed in
advance, in the manufacturing apparatus shown in FIG. 1 and then
manufacturing a light emitting device.
[0132] The substrate is first set in the cassette chamber 120a or
the cassette chamber 120b. Large size substrates (for example, 300
mm.times.360 mm) are set into the cassette chamber 120a or 120b,
while normal size substrates (for example, 127 mm.times.127 mm) are
transported to the tray loading stage 121, and a plurality of
substrates are set in the tray (for example, 300 mm.times.360
mm).
[0133] The substrate, on which a plurality of the thin film
transistors, the anode, and the insulator that covers the edge
portions of the anode are formed, is then transported to the
transporting chamber 118.
[0134] Further, it is preferable to perform annealing for degassing
within a vacuum before forming films that contain organic compounds
in order to remove moisture and other gasses contained in the
substrate. The substrate may be transported to the preprocessing
chamber 128 that is coupled to the transporting chamber 118, and
annealing may be performed there.
[0135] Further, the film formation chamber 112 may form a hole
injecting layer made from a polymeric material by using an inkjet
method, a spin coating method, or the like. An aqueous solution of
poly(ethylene dioxythiophene)/poly(styrene sulfonic acid)
(PEDOT/PSS), an aqueous solution of polyaniline/camphor sulfonic
acid (PANI/CSA), PTPDES, Et-PTPDEK, PPBA, or the like, which acts
as a hole injecting layer (anode buffer layer) may be applied over
the entire surface of the first electrode (anode), and fired. It is
preferable to perform firing in a baking chamber 123. Levelness can
be improved for cases in which a hole injecting layer made from a
polymeric material formed by an application method using a spin
coater or the like. The coverage and uniformity in film thickness
are made satisfactory for films formed thereupon. In particular,
uniform light emission can be obtained because the film thickness
of light emitting layers becomes uniform. In this case, it is
preferable to perform vacuum heating (at 100 to 200.degree. C.)
after forming the hole injecting layer by application, and
immediately before film formation by evaporation. Note that light
emitting layer formation may be performed by evaporation, without
exposure to the ambient atmosphere, if: the surface of the first
electrode (anode) is cleaned by using a sponge; a film of an
aqueous solution of poly(ethylene dioxythiophene)/poly(styrene
sulfonic acid) (PEDOT/PSS), which is formed on the entire surface
by spin coating and has a film thickness of 60 nm, is provisionally
fired at 80.degree. C. for 10 minutes, and then fired at
200.degree. C. for one hour; and in addition, vacuum heating
(heating for 30 minutes at 170.degree. C., then cooling for 30
minutes) is performed immediately before evaporation, for example.
In particular, the influence of unevenness or minute particles
existing on the surface of an ITO film can be reduced by making the
PEDOT/PSS film thick.
[0136] Further, PEDOT/OSS does not have good wettability if applied
on top of an ITO film. It is therefore preferable to increase the
wettability by washing with purified water once after performing a
first application of PEDOT/PSS solution by spin coating. A second
application of PEDOT/PSS solution may be performed by spin coating,
and firing may be performed, thus forming a film having good
uniformity. Note that washing the substrate with purified water
once after performing the first application is effective in
improving surface quality, and is also effective in removing minute
particles and the like.
[0137] Further, film formation is performed over the entire surface
if forming PEDOT/PSS by spin coating, and therefore it is
preferable to selectively remove the PEDOT/PSS from edge surfaces
and circumferential portions of the substrate, and regions that
connect to terminal portions, cathodes, or lower portion wirings,
and the like. It is preferable to perform removal by employing
O.sub.2 ashing or the like in the preprocessing chamber 103a.
[0138] The substrate is next transported from the transporting
chamber 118, which is provided with a substrate transporting
mechanism, to the stocking chamber 101. A substrate inverting
mechanism is provided in the stocking chamber 101 in the
manufacturing apparatus of this embodiment, and the substrate can
be suitably inverted. It is preferable that the stocking chamber
101 be coupled to a vacuum evacuation processing chamber, and that
the stocking chamber 101 be set to ambient atmospheric pressure by
introducing an inert gas after vacuum evaporation.
[0139] The substrate is then transported to the transporting
chamber 102, which is coupled to the stocking chamber 101. It is
preferable to perform vacuum evacuation of the inside of the
transporting chamber 102 in advance, and maintain a vacuum there,
so that as little moisture and oxygen as possible will exist
there.
[0140] Further, a magnetic levitation turbomolecular pump, a cryo
pump, or a dry pump is provided as the vacuum evacuation processing
chamber. It is thus possible to achieve an ultimate pressure of
10.sup.-5 to 10.sup.-6 Pa in the transporting chamber that is
coupled to the stocking chamber. In addition, back diffusion of
impurities from the pump side and from the evacuation system can be
controlled. An inert gas such as nitrogen or a noble gas is used as
the gas introduced in order to prevent the introduction of
impurities within the apparatus. A gas that has been highly
purified by a gas purifier before being introduced within the
apparatus is used. It is therefore necessary to provide a gas
purifier so that the gas is introduced into the evaporation
apparatus after being highly purified. Oxygen, moisture, and other
impurities contained in the gas can thus be removed in advance, and
therefore these impurities can be prevented from being introduced
to the inside of the apparatus.
[0141] Further, the substrate may be transported to the
preprocessing chamber 103a, and a laminate of organic compound
films may be selectively removed if it is intended to remove the
organic compound containing film formed in an unnecessary portion.
The preprocessing chamber 103a has a plasma generating means, and
performs dry etching by exciting one gas, or a plurality of gases
selected from the group consisting of Ar, H, F, and O, thus
generating a plasma.
[0142] Further, it is preferable to perform vacuum heating
immediately before evaporation of the organic compound containing
film in order to eliminate shrinkage. The substrate is transported
to the preprocessing chamber 103a, and annealing for degassing is
performed in a vacuum (pressure equal to or less than
5.times.10.sup.-3 Torr (0.665 Pa), preferably from 10.sup.-6 to
10.sup.-4 Pa) in order to thoroughly remove moisture and other
gasses contained in the substrate. If an organic resin film is used
as an interlayer insulating film material or barrier material, in
particular, organic resin materials tend to easily adsorb moisture
in some cases, and in addition, there is a fear of degassing. It is
therefore effective to perform 30 minutes of natural cooling after
heating at a temperature of 100 to 250.degree. C., preferably of
150.degree. C. to 200.degree. C., for a period equal to or greater
than 30 minutes, for example, and then perform vacuum heating for
removing adsorbed moisture before forming the organic compound
containing layer.
[0143] Further, it is preferable that the preprocessing chamber
103b should be a multiple-stage vacuum heating chamber as shown in
FIG. 13. In FIG. 13, C denotes a vacuum chamber, 1 denotes a
constant temperature bath, 2 denotes a panel heater, 3 denotes a
uniform temperature board (a plate heater), 4 denotes a slot for
heating substrates, 5 denotes a substrate holder. Heat is
transmitted to the uniform temperature board 3 by a thermal
conduction from the panel heater 2, and the uniform temperature
board 3 is heated. Substrates to be processed, which are held in
each slot 4, are uniformly heated by a thermal radiation of an
infrared light, etc. It is possible to place one substrate in one
slot 4, that is, seven substrates in total in the constant
temperature bath 1.
[0144] The substrate is then transported from the transporting
chamber 102 to the film formation chamber 106H (EL layer for HTL
and HIL) after the aforementioned vacuum heating, and evaporation
is performed. The substrate is next transported from the
transporting chamber 102 to the delivery chamber 105, and in
addition, is transported from the delivery chamber 105 to the
transporting chamber 104a without being exposed to the ambient
atmosphere.
[0145] The substrate is then suitably transported to the film
formation chambers 106R (EL layer for red), 106G (EL layer for
green), 106B (EL layer for blue), and 106E (EL layer for ETL and
EIL) that is coupled to the transporting chamber 104a, and low
molecular weight organic compound layers that become hole injecting
layers, hole transporting layers, and light emitting layers are
formed. The film formation chambers 106R, 106G, 106B, 106E, and
106H are explained here.
[0146] A moveable evaporation source holder is installed in each of
the film formation chambers 106R, 106G, 106B, 106E, and 106H. A
plurality of the evaporation source holders are prepared, and they
are provided with a plurality of containers (crucibles) in which EL
materials are enclosed. The evaporation source holders are
installed in the film formation chambers in this state.
[0147] It is preferable that the installation of the EL materials
to the film formation chambers be performed using the manufacturing
system shown below. That is, it is preferable that film formation
be performed using containers (typically crucibles) within which
the EL materials are received in advance by a material
manufacturer. In addition, it is preferable to perform installation
without exposure to the ambient atmosphere. At the time of
transportation from the material manufacturer, it is preferable
that the crucibles be introduced to the film formation chambers in
a state where they are sealed in second containers. It is desirable
that the installation chambers 126R, 126G, 126B, 126H, and 126E,
which have vacuum evacuation means coupled to the film formation
chambers 106R, 106G, 106B, 106H, and 106E, respectively, be placed
under a vacuum, or under an inert gas atmosphere, and that the
crucibles be removed from the second containers within the vacuum,
or within the inert gas atmosphere, and then be set in film
formation chambers. The crucibles and the EL materials received in
the crucibles can thus be prevented from being contaminated. Note
that it is also possible to stock metal masks in the installation
chambers 126R, 126G, 126B, 126H, and 126E.
[0148] Light emitting elements that display single color
(specifically, white) or full color (specifically, red, green, and
blue) light emission overall can be formed by suitably selecting
the EL materials installed in the film formation chambers 106R,
106G, 106B, 106H, and 106E.
[0149] Note that organic compound layers that emit white color
light can be roughly divided into two types for cases where the
light emitting layer has different colors of light emission for
lamination. One is a three wavelength type containing three primary
colors, i.e., red, green, and blue, while the other is a two
wavelength type that utilizes a complementary color relationship
between blue and yellow, or between cyan and orange. A plurality of
evaporation source holders are prepared in one film formation
chamber if white color light emitting elements that use the three
wavelength type of light emission are obtained. An aromatic diamine
(TPD) is enclosed in a first evaporation source holder for forming
a white color light emitting layer, p-EtTAZ is enclosed in a second
evaporation source holder for forming a white color light emitting
layer, and Alq.sub.3 is enclosed in a third evaporation source
holder for forming a white color light emitting layer. An EL
material in which Nile Red, a red color light emitting pigment, is
added to Alq.sub.3 is enclosed in a fourth evaporation source
holder for forming a white color light emitting layer, and
Alq.sub.3 is enclosed in a fifth evaporation source holder. The
evaporation source holders are installed in each of the film
formation chambers in this state. Movement of the first through the
fifth evaporation source holders is then started in order, and
evaporation and lamination are performed on the substrate.
Specifically, TPD is sublimated from the first evaporation source
holder due to heating, and is evaporated on the entire substrate
surface. P-EtTAZ is sublimated next 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, and Alq.sub.3 is sublimated from the
fifth evaporation source holder. The sublimated materials are
evaporated over the entire substrate surface. A white color light
emitting element can be obtained if a cathode is formed
thereafter.
[0150] After suitably laminating the organic compound containing
layers, and after transporting the substrate from the transporting
chamber 104a to the delivery chamber 107, the substrate is next
moved from the delivery chamber 107 to the transporting chamber
108, all without exposure to the ambient atmosphere.
[0151] The substrate is next transported to the film formation
chamber 110 by a transporting mechanism installed within the
transporting chamber 108, and a cathode is formed. The cathode is a
metallic film (a film made from an alloy such as MgAg, MgIn, AlLi,
CaN, or the like, or an element that resides in group 1 or group 2
of the periodic table and aluminum by co-evaporation) formed by an
evaporation method using resistive heating. The cathode may also be
formed in the film formation chamber 132 by using sputtering.
Further, a film made from a transparent conductive film (ITO
(indium tin oxide alloy), indium oxide zinc oxide alloy
(In.sub.2O.sub.3--ZnO), zinc oxide (ZnO) or the like) may also be
formed in the film formation chamber 109 by using sputtering.
[0152] Furthermore, the substrate may also be transported to the
film formation chamber 113 that is coupled to the transporting
chamber 108, and a protective film made from a silicon nitride film
or a silicon oxynitride film may be formed. A target made from
silicon, a target made from silicon oxide, or a target made from
silicon nitride is provided here within the film formation chamber
113. For example, a silicon nitride film can be formed by using the
target made from silicon and by making the atmosphere within the
film formation chamber into a nitrogen atmosphere, or into an
atmosphere that contains nitrogen and argon.
[0153] Light emitting elements having a laminate structure can be
formed by the processes described above.
[0154] The substrate, upon which the light emitting elements are
formed, is then transported from the transporting chamber 108 to
the delivery chamber 111 without exposing to the ambient
atmosphere, and in addition, the substrate is transported form the
delivery chamber 111 to the transporting chamber 114. The
substrate, upon which the light emitting elements are formed, is
transported next from the transporting chamber 114 to the sealing
chamber 116.
[0155] A sealing substrate is prepared and set into the loading
chamber 117 from the outside. Note that it is preferable to perform
annealing in advance within a vacuum in order to remove impurities
such as moisture. A sealing material is then formed in which the
sealing substrate is bonded to the substrate upon which the light
emitting element is formed. At this time, the sealing material is
formed in the sealing chamber. Then, the sealing substrate with the
formed sealing material is transported to the sealing substrate
stocking chamber 130. Note that a drying agent may also be formed
on the sealing substrate in the sealing chamber. Note also that,
although an example of forming a sealing material on the sealing
substrate is shown here, the present invention is not limited to
this structure. A sealing material may also be formed on the
substrate having the light emitting elements formed thereon.
[0156] The substrate and the sealing substrate are then bonded in
the sealing chamber 116, and UV light is then irradiated to the
pair of bonded substrates by an ultraviolet light irradiation
mechanism provided in the sealing chamber 116, thus setting the
sealing material. Note that, although an ultraviolet light setting
resin is used as the sealing material here, the present invention
is not limited to the use of this material. Other materials may
also be employed, provided that they are adhesive materials.
[0157] The pair of bonded substrates is next transported from the
sealing chamber 116 to the transporting chamber 114, and then from
the transporting chamber 114 to the extraction chamber 119, and
removed. The pathways described above are shown by arrows in FIG.
9.
[0158] Processing thus takes place up through completely sealing
the light emitting elements into a sealed space, without exposure
to the ambient atmosphere, by using the manufacturing apparatus
shown in FIG. 1. It therefore becomes possible to manufacture a
light emitting device having high reliability. Note that, although
the atmosphere inside the transporting chambers 114 and 118 is
repeatedly changed from a vacuum to a nitrogen atmosphere at
ambient pressure, it is preferable that a vacuum always be
maintained inside the transporting chambers 102, 104a, and 108.
[0159] Note that, although not shown here, a control apparatus is
provided for controlling the pathways in which the substrate is
moved to each of the processing chambers, thus achieving complete
automation.
[0160] Further, it is also possible to form upward emission (double
sided emission) light emitting elements in the manufacturing
apparatus shown in FIG. 1. An organic compound containing layer is
formed on a substrate having a transparent conductive film (or a
metallic film (TiN)) as an anode, and thereafter a transparent or a
translucent cathode (for example, a laminate of a thin metallic
film (Al, Ag) and a transparent conductive film) is formed.
[0161] Further, it is also possible to form bottom emission light
emitting elements in the manufacturing apparatus shown in FIG. 1.
An organic compound containing layer is formed on a substrate
having a transparent conductive film as an anode, and thereafter a
cathode made from a metallic film (Al, Ag) is formed.
[0162] Further, this embodiment can be freely combined with the
embodiment mode.
[0163] [Embodiment 2]
[0164] An example having one portion that differs from the
manufacturing apparatus of Embodiment 1 is disclosed in this
embodiment. Specifically, an example of a manufacturing apparatus
including a transporting chamber 1004a provided with six film
formation chambers 1006R (EL layer for red), 1006G (EL layer for
green), 1006B (EL layer for blue), 1006R' (EL layer for red),
1006G' (EL layer for green), and 1006B' (EL layer for blue) is
shown in FIG. 10.
[0165] Note that portions identical to those of FIG. 1 are shown by
using the same reference numerals in FIG. 10. Further, explanations
of portions identical to those of FIG. 1 are omitted here for
brevity.
[0166] An example of an apparatus capable of manufacturing full
color light emitting elements in parallel is shown in FIG. 10.
[0167] Similarly to Embodiment 1, vacuum heating is performed on
substrates in the preprocessing chamber 103b, and the substrates
are then transported from the transporting chamber 102 to the
transporting chamber 1004a via the delivery chamber 105. Films are
laminated on a first substrate through a pathway via the film
formation chambers 1006R, 1006G, and 1006B, and films are laminated
on a second substrate through a pathway via the film formation
chambers 1006R', 1006G', and 1006B'. Throughput can thus be
increased by performing evaporation on a plurality of substrates in
parallel. Subsequent processes may be performed in accordance with
Embodiment 1. A light emitting device can be completed by
performing sealing after cathode formation.
[0168] Further, R, G, and B color hole transporting layers, light
emitting layers, and electron transporting layers may also be
laminated in three different film formation chambers, as shown in
FIG. 11 showing the sequence from substrate insertion to substrate
extraction. Note that mask alignment is performed before each
evaporation in FIG. 11, so that the films are only formed in
predetermined regions. It is preferable to use different masks for
each of the different colors in order to prevent color mixing, and
three masks are necessary in this case. The following procedures
may be performed, for example, if a plurality of substrates are
processed. The first substrate is placed in the first film
formation chamber, and a layer that contains a red color light
emitting organic compound is formed. The first substrate is then
removed, and placed next in the second film formation chamber. The
second substrate is placed in the first film formation chamber
while a layer that contains a green color light emitting organic
compound is formed on the first substrate, and a layer that
contains the red color light emitting organic compound is formed on
the second substrate. The first substrate is lastly placed in the
third film formation chamber. The second substrate is placed in the
second film formation chamber, and then the third substrate is
placed in the first film formation chamber, while a layer that
contains a blue color light emitting organic compound is formed on
the first substrate. Laminations may thus be performed
sequentially.
[0169] Further, the R, G, and B color hole transporting layers,
light emitting layers, and electron transporting layers may also be
laminated in the same film formation chamber, as shown in FIGS. 12A
and 12B showing the sequence from substrate insertion to substrate
extraction. Three type of material layers, corresponding to R, G,
and B, may be formed selectively by performing mask positioning
through shifting during mask alignment, as shown in FIG. 12B, if
the R, G, and B color hole transporting layers, light emitting
layers, and electron transporting layers are laminated
consecutively in the same film formation chamber. Note that
reference numeral 10 denotes a substrate in FIG. 12B, reference
numeral 15 denotes shutters, reference numeral 17 denotes
evaporation source holders, reference numeral 18 denotes
evaporation materials, and reference numeral 19 denotes vaporized
evaporation materials. States of shifting an evaporation mask 14
for each of the organic compound containing layers is shown. The
mask is shared in this case, and only one mask is used.
[0170] Further, the substrate 10 and the evaporation mask 14 are
disposed in a film formation chamber (not shown). Furthermore, the
alignment of the evaporation mask 14 may be confirmed by using a
CCD camera (not shown). Containers in which the evaporation
materials 18 are enclosed are disposed in the evaporation source
holders 17. The film formation chamber 11 is vacuum-evacuated to a
degree of vacuum equal to or less than 5.times.10.sup.-3 Torr
(0.665 Pa), preferably from 10.sup.-6 to 10.sup.-4 Pa. Further, the
evaporation materials are sublimated (gasified) in advance by
resistive heating during evaporation, and scatter in the direction
of the substrate 10 by opening the shutter 15 during evaporation.
The sublimated evaporation material 19 scatters upward, and is
selectively evaporated on the substrate 10 through an opening
portion formed in the evaporation mask. Note that it is desirable
that the film formation speed, the moving speed of the evaporation
source holder, and the opening and closing of the shutter be made
controllable by a microcomputer. It thus becomes possible to
control the evaporation speed by the speed at which the evaporation
source holder moves. Further, evaporation can be performed while
measuring the film thickness of the evaporation film by using a
liquid crystal oscillator provided in the film formation chamber.
Changes in the mass of the film evaporated on the liquid crystal
oscillator can be measured as changes in resonance frequency for
cases where the film thickness of the evaporation film is measured
by using the liquid crystal oscillator. In the evaporation
apparatus, the gap distance d between the substrate 10 and the
evaporation source holder 17 during evaporation is shortened to,
typically equal to or less than 30 cm, preferably equal to or less
than 20 cm, more preferably from 5 cm to 15 cm. The utilization
efficiency and throughput of the evaporation materials is therefore
markedly improved. Further, a mechanism capable of moving the
evaporation source holder 17 in the x-direction and in the
y-direction in the film formation chamber, with the evaporation
source holder maintained in a horizontal orientation, is provided.
The evaporation source holder 17 is moved here in a zigzag manner
in a planar plane, as shown in FIG. 2A and FIG. 2B.
[0171] Further, if a hole transporting layer and an electron
transporting layer are commonly used, the hole transporting layer
is formed first, after which a light emitting layer made from a
different material is selectively laminated by using a different
mask, and then the electron transporting layer is laminated. Three
masks are thus used in this case.
[0172] Furthermore, this embodiment can be freely combined with the
embodiment mode or Embodiment 1.
[0173] In accordance with the present invention, substrate rotation
is not necessary, and therefore an evaporation apparatus capable of
handling large surface area substrates can be provided. Further, an
evaporation apparatus capable of obtaining a uniform film
thickness, even if large surface area substrates are used, can be
provided.
[0174] Furthermore, the distance between the substrate and an
evaporation source holder can be shortened in accordance with the
present invention, and miniaturization of the evaporation apparatus
can be achieved. The evaporation apparatus becomes smaller, and
therefore the amount of sublimated evaporation materials that
adhere to internal walls or protective shields in film formation
chambers is reduced, and the evaporation materials can be
effectively utilized.
[0175] Further, the present invention can provide a manufacturing
apparatus in which a plurality of film formation chambers for
performing evaporation processing are disposed in succession.
Throughput of the light emitting device can be enhanced if parallel
processing is performed in the plurality of film formation
chambers.
[0176] In addition, the present invention can provide a
manufacturing system that makes it possible to directly install
containers that enclose evaporation materials, film thickness
monitors, and the like in the evaporation apparatus, without
exposure to the atmosphere. Handling of the evaporation materials
is facilitated in accordance with the present invention, and the
mixing in of impurities into the evaporation materials can be
avoided. Containers sealed by a material manufacturer can be
directly installed in the evaporation apparatus in accordance with
this type of manufacturing system, and therefore oxygen and
moisture can be prevented from adhering to the evaporation
materials, and it becomes possible to handle even more very highly
purified light emitting elements in the future.
* * * * *