U.S. patent application number 13/024984 was filed with the patent office on 2011-06-09 for manufacturing apparatus.
This patent application is currently assigned to SEMICONDUCTOR ENERGY LABORATORY CO., LTD.. Invention is credited to Masakazu MURAKAMI, Shunpei YAMAZAKI.
Application Number | 20110132260 13/024984 |
Document ID | / |
Family ID | 29545038 |
Filed Date | 2011-06-09 |
United States Patent
Application |
20110132260 |
Kind Code |
A1 |
YAMAZAKI; Shunpei ; et
al. |
June 9, 2011 |
MANUFACTURING APPARATUS
Abstract
A manufacturing apparatus is provided, which can improve a
utilization efficiency of an evaporation material, reduce
manufacturing costs of a light emitting device having an organic
light emitting element, and shorten manufacturing time necessary to
manufacture a light emitting device. According to the present
invention, a multi-chamber manufacturing apparatus having plural
film forming chambers includes a first film forming chamber for
subjecting a first substrate to evaporation and a second film
forming chamber for subjecting a second substrate to evaporation.
In each film forming chamber, plural organic compound layers are
laminated, thereby improving the throughput. Further, it is
possible that the respective substrates in the plural film forming
chambers are subjected to evaporation in the same manner in
parallel, while another film forming chamber undergoes
cleaning.
Inventors: |
YAMAZAKI; Shunpei; (Tokyo,
JP) ; MURAKAMI; Masakazu; (Atsugi, JP) |
Assignee: |
SEMICONDUCTOR ENERGY LABORATORY
CO., LTD.
Atsugi-shi
JP
|
Family ID: |
29545038 |
Appl. No.: |
13/024984 |
Filed: |
February 10, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12203802 |
Sep 3, 2008 |
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13024984 |
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10438194 |
May 15, 2003 |
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12203802 |
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Current U.S.
Class: |
118/719 |
Current CPC
Class: |
H01L 21/67745 20130101;
Y10S 414/135 20130101; H01L 21/67276 20130101; Y10S 438/908
20130101; C23C 14/12 20130101; C23C 14/568 20130101; C23C 14/243
20130101; H01L 51/001 20130101 |
Class at
Publication: |
118/719 |
International
Class: |
C23C 16/448 20060101
C23C016/448 |
Foreign Application Data
Date |
Code |
Application Number |
May 17, 2002 |
JP |
2002-143803 |
Claims
1. An evaporation apparatus comprising: a first film forming
chamber comprising: an evaporation source holder which is capable
of holding a first container; a shutter attached to the evaporation
source holder; a first setting chamber connected to the first film
forming chamber, the first setting chamber comprising: a base which
is capable of containing the first container; a transfer means for
transferring the first container between the base and the
evaporation source holder, wherein the evaporation source holder is
movable in the first film forming chamber.
2. The evaporation apparatus according to claim 1, wherein the base
is capable of holding a second container which is capable of
containing the first container.
3. The evaporation apparatus according to claim 1, further
comprising means for heating the first container provided in the
evaporation source holder.
4. The means for transferring evaporation apparatus according to
claim 1, further comprising a transfer chamber connected to the
first film forming chamber, the transfer chamber comprising a
substrate.
5. The evaporation apparatus according to claim 4, further
comprising: a second film forming chamber connected to the transfer
chamber, the second film forming chamber comprising the same
components as the first film forming chamber; and a second setting
chamber connected to the second film forming chamber, the second
setting chamber comprising the same components as the first film
forming chamber.
6. An evaporation apparatus comprising: a first film forming
chamber comprising: an evaporation source holder which is capable
of holding a plurality of first containers and arranged in a shape
of lattice; a plurality of shutters attached to the evaporation
source holder and arranged in the shape of lattice; a first setting
chamber connected to the first film forming chamber, the first
setting chamber comprising: a base which is capable of containing
the plurality of first containers; a transfer means for
transferring the plurality of first containers between the base and
the evaporation source holder, wherein the evaporation source
holder is movable in the first film forming chamber.
7. The evaporation apparatus according to claim 6, wherein the base
is capable of holding a second container which is capable of
containing one of the plurality of first containers.
8. The evaporation apparatus according to claim 6, further
comprising means for heating the plurality of first containers
provided in the evaporation source holder.
9. The evaporation apparatus according to claim 6, further
comprising a transfer chamber connected to the first film forming
chamber, the transfer chamber comprising means for transferring a
substrate.
10. The evaporation apparatus according to claim 9, further
comprising: a second film forming chamber connected to the transfer
chamber, the second film forming chamber comprising the same
components as the first film forming chamber; and a second setting
chamber connected to the second film forming chamber, the second
setting chamber comprising the same components as the first film
forming chamber.
11. An evaporation apparatus comprising: a first film forming
chamber comprising: an evaporation source holder which is capable
of holding a plurality of first containers and arranged in a linear
shape; a plurality of shutters attached to the evaporation source
holder and arranged in the linear shape; a first setting chamber
connected to the first film forming chamber, the first setting
chamber comprising: a base which is capable of containing the
plurality of first containers; a transfer means for transferring
the plurality of first containers between the base and the
evaporation source holder, wherein the evaporation source holder is
movable in the first film forming chamber.
12. The evaporation apparatus according to claim 11, wherein the
base is capable of holding a second container which is capable of
containing one of the plurality of first containers.
13. The evaporation apparatus according to claim 11, further
comprising means for heating the plurality of first containers
provided in the evaporation source holder.
14. The evaporation apparatus according to claim 11, further
comprising a transfer chamber connected to the first film forming
chamber, the transfer chamber comprising means for transferring a
substrate.
15. The evaporation apparatus according to claim 14, further
comprising: a second film forming chamber connected to the transfer
chamber, the second film forming chamber comprising the same
components as the first film forming chamber; and a second setting
chamber connected to the second film forming chamber, the second
setting chamber comprising the same components as the first film
forming chamber.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a manufacturing apparatus
used for film formation of a material that can be formed into a
film by evaporation (hereinafter referred to as evaporation
material) and a manufacturing method of a light emitting device
typified by an EL element. In particular, the present invention
relates to a technique using an organic material as the evaporation
material and being effective when manufacturing a light emitting
device. Note that the term "light emitting device" in this
specification refers to an image display device, a light emitting
device, or a light source (including illuminating devices). Also
included in the definition of the light emitting device are: a
module in which a connector such as an FPC (flexible printed
circuit), a TAB (tape automated bonding) tape, or a TCP (tape
carrier package) is attached to a light emitting device; a module
in which a printed wiring board is provided on the tip of a TAB
tape or a TCP; and a module in which an IC (integrated circuit) is
mounted directly to a light emitting element by a COG (chip on
glass) method.
[0003] 2. Description of the Related Art
[0004] In recent years, the research of light emitting devices
using an EL element as a self-luminous element has become active.
In particular, light emitting devices using an organic material as
an EL material are attracting more attention. The light emitting
devices are called organic EL displays (OELD) or organic light
emitting diodes (OLED).
[0005] Note that an EL element has a layer (hereinafter referred to
as EL layer) containing an organic compound in which luminescence
developed by applying an electric field (electroluminescence) is
obtained, an anode, and a cathode. The types of the organic
compound luminescence includes light emission when returning from a
singlet excitation state to a ground state (fluorescence) and light
emission when returning from a triplet excitation state to a ground
state (phosphorescence). Both types of light emission can be
applied to a light emitting device produced by a film forming
apparatus and a film formation method according to the present
invention.
[0006] Unlike liquid crystal display devices, light emitting
devices are of a self-luminous type, thereby causing no problem of
a view angle. More specifically, the light emitting devices are
more suitable as a display used outside than the liquid crystal
displays. Thus, the use of the light emitting devices in various
forms has been proposed.
[0007] An EL element has a structure in which an EL layer is
sandwiched between a pair of electrodes, and the EL layer normally
has a laminate structure. A typical example of the laminate
structure is one composed of "a hole transporting layer/a light
emitting layer/and an electron transporting layer". Most of the
light emitting devices currently under research and development
adopt the structure due to its extremely high light emitting
efficiency.
[0008] Alternatively, another laminate structure may be used in
which: a hole injecting layer, a hole transporting layer, a light
emitting layer, and an electron transporting layer are laminated
onto an anode in the stated order; or a hole injecting layer, a
hole transporting layer, a light emitting layer, an electron
transporting layer, and an electron injecting layer are laminated
onto an anode in the stated order. Fluorescent pigments and the
like may also be doped into the light emitting layers. Further, all
of the above layers may be formed using only low-molecular weight
materials, or may be formed using only high-molecular weight
materials.
[0009] Further, EL materials used to form an EL layer are broadly
divided into low-molecular weight (monomer-based) materials and
high-molecular weight (polymer-based) materials, while the
low-molecular weight materials are formed into films mainly by
evaporation.
[0010] The EL material is extremely likely to deteriorate, because
the EL material is easily oxidized due to presence of oxygen or
moisture. Thus, a photolithography step cannot be performed after
film formation. In order to form a pattern, it is necessary to use
a mask (hereinafter referred to as evaporation mask) having an
opening portion to separate out the pattern region at the same time
of the film formation. Therefore, most of the sublimated organic EL
materials are adhered to an inner wall of a film forming chamber or
an adhesion proof shield (protective plate for preventing an
evaporation material from adhering to the inner wall of the film
forming chamber). As a result, an evaporation apparatus needs
regular maintenance such as a cleaning process for removing adhered
substances from the inner wall of the film forming chamber and the
adhesion proof shield, thereby making it inevitable to temporarily
stop a manufacturing line for mass production during the
maintenance.
[0011] In order to improve uniformity of a film thickness,
conventional evaporation apparatuses have a larger interval between
a substrate and an evaporation source, so that the apparatuses per
se have a larger size. Also, the conventional evaporation
apparatuses have a structure, as shown in FIG. 22, in which the
interval between a substrate and an evaporation source is set to 1
m or more and the substrate is rotated to obtain a film having a
uniform thickness. Further, the evaporation apparatuses have such a
structure as to rotate the substrate, so that there is a limitation
on an evaporation apparatus for attaining a large-area substrate.
Also, the interval between a substrate and an evaporation source is
large, so that a speed of film formation is reduced and a longer
time is necessary to exhaust a film forming chamber, thereby
reducing the throughput.
[0012] In addition, in the conventional evaporation apparatuses,
the utilization efficiency of an expensive EL material is as
extremely low as approximately 1% or low. Thus, the manufacturing
costs of a light emitting device are extremely high.
[0013] An EL material is extremely expensive and costs higher per
gram than gold costs per gram. Therefore it is desired to use an EL
material as efficiently as possible. However, in the conventional
evaporation apparatuses, the utilization efficiency of the
expensive EL material is low.
SUMMARY OF THE INVENTION
[0014] The present invention has been made in view of the above,
and therefore has an object to provide an evaporation apparatus and
a manufacturing apparatus, which are capable of improving a
utilization efficiency of an EL material, excellent in uniformity,
and excellent in throughput.
[0015] Due to evaporation being performed in vacuum, it takes a
long time to set an inside of a film forming chamber to vacuum and
a time necessary for each step differs in every film forming
chamber. Thus, it is difficult to design manufacturing processes as
automated steps, thereby putting a limitation on improvement in
productivity. In particular, it takes a long time to deposit and
laminate layers containing an organic compound by evaporation, so
that there is a limitation on reduction in a processing time per
substrate. In view of the above, the present invention has another
object to reduce a processing time per substrate.
[0016] Further, another object of the present invention is to
provide a manufacturing apparatus capable of maintenance of a film
forming chamber without temporarily stopping a manufacturing
line.
[0017] Further, according to the present invention, there is
provided a method of depositing an EL material by evaporation
efficiently on a large-area substrate having a size such as 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.
[0018] Further, according to the present invention, there is
provided a manufacturing system capable of preventing impurities
from mixing into an EL material.
[0019] According to the present invention, there is provided a
multi-chamber manufacturing apparatus having plural film forming
chambers, including a first film forming chamber for subjecting a
first substrate to evaporation and a second film forming chamber
for subjecting a second substrate to evaporation, characterized in
that plural organic compound layers are laminated in respective
film forming chambers in parallel, thereby reducing a processing
time per substrate. More specifically, after the first substrate is
loaded from a transfer chamber into the first film forming chamber,
a surface of the first substrate is subjected to evaporation, while
after the second substrate is loaded from the transfer chamber into
the second film forming chamber, a surface of the second substrate
is also subjected to evaporation. In FIG. 1, four film forming
chambers are connected to a transfer chamber 102. Therefore, as
shown in FIG. 6A showing an example of a sequence from loading of
substrates to unloading of the substrates, it is possible that four
substrates are loaded into the respective film forming chambers and
sequentially subjected to evaporation in parallel.
[0020] According to the present invention, in order to maintain
uniform cycle times during mass production, plural chambers are
provided at least as evaporation chambers and heating chambers, and
a single chamber may be provided as another chamber having a
relatively short processing time. Accordingly, the present
invention allows efficient mass production.
[0021] According to a first structure of the present invention
disclosed in this specification, there is provided a manufacturing
apparatus, including:
[0022] a load chamber;
[0023] a transfer chamber that is connected to the load chamber;
and
[0024] plural film forming chambers that are connected to the
transfer chamber, wherein:
[0025] the plural film forming chambers are each connected to a
vacuum-exhaust process chamber for setting an inside of the film
forming chamber to vacuum, and each include: alignment means for
performing position alignment of a mask and a substrate; an
evaporation source; and means for heating the evaporation source;
and
[0026] in at least two of the plural film forming chambers,
surfaces of substrates loaded into the respective film forming
chambers are subjected to evaporation in parallel.
[0027] Further, not only the film forming chambers in which an
organic compound layer is formed but also the film forming
chambers, sealing chambers, and pretreatment chambers in which
electrodes (cathodes or anodes) are formed on the organic compound
layer may be provided in plural number, respectively, and the
respective forming processes may be performed in parallel
similarly. Therefore, according to a second structure of the
present invention disclosed in this specification, there is
provided a manufacturing apparatus, including:
[0028] a load chamber;
[0029] a transfer chamber that is connected to the load
chamber;
[0030] plural film forming chambers that are connected to the
transfer chamber, and
[0031] plural sealing chambers, wherein:
[0032] the plural film forming chambers are each connected to a
vacuum-exhaust process chamber for setting an inside of the film
forming chamber to vacuum, and each include: alignment means for
performing position alignment of a mask and a substrate; an
evaporation source; and means for heating the evaporation
source;
[0033] in at least two of the plural film forming chambers,
surfaces of substrates loaded into the respective film forming
chambers are subjected to evaporation in parallel; and
[0034] each substrate is assigned to one of the plural sealing
chambers to be sealed therein.
[0035] Further, according to the present invention, even though the
processing number of substrates is slightly reduced, the effective
evaporation process can be realized. For example, as shown in FIG.
6B showing an example of a sequence from loading of substrates to
unloading of the substrates, even when a fourth film forming
chamber is undergoing the maintenance, evaporation can be performed
in first to third film forming chambers sequentially without
temporarily stopping the production line. Therefore, according to a
third structure of the present invention disclosed in this
specification, there is provided a manufacturing apparatus,
including:
[0036] a load chamber;
[0037] a transfer chamber that is connected to the load chamber;
and
[0038] plural film forming chambers that are connected to the
transfer chamber, wherein:
[0039] the plural film forming chambers are each connected to a
vacuum-exhaust process chamber for setting an inside of the film
forming chamber to vacuum, and each include: alignment means for
performing position alignment of a mask and a substrate; an
evaporation source; and means for heating the evaporation source;
and
[0040] in at least two of the plural film forming chambers,
surfaces of substrates loaded into the respective film forming
chambers are subjected to evaporation in parallel, and in at least
one of the plural film forming chambers, the inside of the film
forming chamber undergoes cleaning.
[0041] Further, in the case of forming a single-color light
emitting device, as shown in FIG. 2A showing a sequence from
loading of substrates to unloading of the substrates, a hole
transporting layer (referred to as HTL), a light emitting layer,
and an electron transporting layer (referred to as ETL) are
continuously laminated in the same film forming chamber, thereby
improving the throughput. When the hole transporting layer, the
light emitting layer, and the electron transporting layer are
continuously laminated in the same film forming chamber, as shown
in FIGS. 9A and 9B, plural evaporation source holders (evaporation
source holders each moving in the direction X or in the direction
Y) may be provided in one film forming chamber. By using an
evaporation apparatus in FIGS. 9A and 9B, a utilization efficiency
of an evaporation material can be improved.
[0042] The respective structures described above are characterized
in that in at least two of the plural film forming chambers,
evaporation processes of layers containing the same organic
compound are performed in parallel.
[0043] Further, as shown in FIG. 6A showing an example of a
sequence from loading of substrates to unloading of the substrates,
a transfer path for a substrate is divided into the same number of
paths as that of the film forming chambers arranged in connection
to each transfer chamber, so that film formation can be efficiently
performed in order. Note that an example of the path for one
substrate from loading of substrates to unloading of the substrates
is shown by the arrows in FIG. 3. Therefore, according to a fourth
structure of the present invention disclosed in this specification,
there is provided a manufacturing apparatus, including:
[0044] a load chamber;
[0045] a transfer chamber that is connected to the load chamber;
and
[0046] plural film forming chambers that are connected to the
transfer chamber, wherein:
[0047] the plural film forming chambers are each connected to a
vacuum-exhaust process chamber for setting an inside of the film
forming chamber to vacuum, and each include: alignment means for
performing position alignment of a mask and a substrate; an
evaporation source; and means for heating the evaporation source;
and
[0048] plural substrates loaded into the load chamber are each
assigned to one of the plural film forming chambers in the transfer
chamber to be loaded thereinto, and each substrate undergoes
processes along one of different paths whose number is the same as
that of the film forming chambers.
[0049] Further, in the case of forming a full-color light emitting
device, as shown in FIG. 2B, a hole transporting layer, a light
emitting layer, and an electron transporting layer may preferably
be continuously laminated in the same film forming chamber. When
the hole transporting layer, the light emitting layer, and the
electron transporting layer are continuously laminated in the same
film forming chamber, there may be used such a film forming
apparatus as shown in FIGS. 9A and 9B, that is, an evaporation
apparatus provided with plural, at least three or more, evaporation
source holders (evaporation source holders each moving in the
direction X or in the direction Y) in one film forming chamber.
Note that as shown in FIG. 4 showing a sequence from loading of
substrates to unloading of the substrates, all the necessary
organic layers, for example, the hole transporting layer, the light
emitting layer, and the electron transporting layer may
continuously be laminated in different three film forming chambers
(a film forming chamber for a red light emitting element, a film
forming chamber for a blue light emitting element, and a film
forming chamber for a green light emitting element). For example,
the hole transporting layer, the light emitting layer, and the
electron transporting layer which are to compose a red light
emitting element are selectively laminated by using an evaporation
mask (R) in a first chamber; the hole transporting layer, the light
emitting layer, and the electron transporting layer which are to
compose a blue light emitting element are selectively laminated by
using an evaporation mask (B) in a second chamber; and the hole
transporting layer, the light emitting layer, and the electron
transporting layer which are to compose a green light emitting
element are selectively laminated by using an evaporation mask (G)
in a third chamber, thereby realizing full-color display. Note that
in FIG. 4, mask alignment is performed before evaporation in each
chamber to perform film formation in a predetermined region.
[0050] Further, in the case where the hole transporting layer, the
light emitting layer, and the electron transporting layer are
laminated in one chamber, in order to realize the full-color
display, for example, materials (organic materials to become the
hole transporting layer and the electron transporting layer)
optimum for a given color (R, G, or B) can be selected
appropriately. The feature of the present invention also resides in
that the film thicknesses of those layers can be changed in
accordance with colors. Therefore, different materials can be used
for all the nine types of layers in total: the hole transporting
layer, the light emitting layer, and the electron transporting
layer for R; the hole transporting layer, the light emitting layer,
and the electron transporting layer for G; and the hole
transporting layer, the light emitting layer, and the electron
transporting layer for B. Note that organic materials to become the
hole transporting layer or the electron transporting layer may be
used as the common materials.
[0051] Further, in the case where the hole transporting layers, the
light emitting layers, and the electron transporting layers for R,
G, and B are laminated in the different three film forming
chambers, an example of the path for one substrate is shown simply
by the arrows in FIG. 5. For example, after a first substrate is
loaded into a first film forming chamber, a layer containing an
organic compound for red light emission is formed into a laminate
film, and then the first substrate is unloaded. Subsequently, after
the first substrate is loaded into a second film forming chamber, a
layer containing an organic compound for green light emission is
formed into a laminate film, while after a second substrate is
loaded into the first film forming chamber, a layer containing an
organic compound for red light emission may be laminated to the
second substrate to form a film. Lastly, after the first substrate
is loaded into a third film forming chamber, a layer containing an
organic compound for blue light emission is formed into a laminate
film, while after the second substrate is loaded into the second
film forming chamber, a third substrate is loaded into the first
film forming chamber, and layers may sequentially be laminated to
the respective substrates.
[0052] Further, the present invention is not limited to the
structure in which the hole transporting layer, the light emitting
layer, and the electron transporting layer are continuously
laminated in the same chamber. However, the hole transporting
layer, the light emitting layer, and the electron transporting
layer may be laminated in plural chambers connected to each other.
For example, the hole transporting layer to compose a green light
emitting element is formed into a film in the first chamber, the
light emitting layer to compose the green light emitting element is
formed into a film in the second chamber, and the electron
transporting layer to compose the green light emitting element is
formed into a film in the third chamber. Accordingly, the layers
containing an organic compound for green light emission may be
formed into laminate films.
[0053] Further, in the above description, as the typical example of
layers containing an organic compound arranged in a position
between a cathode and an anode, the laminate structure of the three
layers consisting of the hole transporting layer, the light
emitting layer, and the electron transporting layer. However, there
is no particular limitation thereon. Another laminate structure may
be used in which: a hole injecting layer, a hole transporting
layer, a light emitting layer, and an electron transporting layer
are laminated onto an anode in the stated order; or a hole
injecting layer, a hole transporting layer, a light emitting layer,
an electron transporting layer, and an electron injecting layer are
laminated onto an anode in the stated order. Alternatively, a
double layer structure or a single layer structure may be used.
Fluorescent pigments and the like may also be doped into the light
emitting layers. Also, examples of the light emitting layers
include a light emitting layer having hole transportability and a
light emitting layer having electron transportability. Further, all
of the above layers may be formed using only low-molecular weight
materials, or one or several layers of the above layers may be
formed using high-molecular weight materials. Note that in this
specification, the layers provided between the cathode and the
anode are generically referred to as a layer (EL layer) containing
an organic compound. Therefore, the hole injecting layer, the hole
transporting layer, the light emitting layer, the electron
transporting layer, and the electron injecting layer which are
described above are all included in the EL layers. In addition, the
layer (EL layer) containing an organic compound may also contain an
inorganic material such as silicon.
[0054] Note that a light emitting element (EL element) has a layer
(hereinafter referred to as EL layer) containing an organic
compound in which luminescence developed by applying an electric
field (electroluminescence) is obtained, an anode, and a cathode.
The types of the organic compound luminescence includes light
emission when returning from a singlet excitation state to a ground
state (fluorescence) and light emission when returning from a
triplet excitation state to a ground state (phosphorescence). Both
types of light emission can be applied to a light emitting device
produced according to the present invention.
[0055] Further, in the light emitting device according to the
present invention, there is no particular limitation on a drive
method for screen display. For example, a dot-sequential drive
method, a line-sequential drive method, a plane-sequential drive
method, and the like are used. Typically, the line-sequential drive
method is used, and a time-division gray scale drive method and an
area gray scale drive method may also be used appropriately. Also,
a picture signal inputted to a source line of the light emitting
device may be an analog signal or may be a digital signal, so that
drive circuits and the like may be designed appropriately in
accordance with picture signals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0056] In the accompanying drawings:
[0057] FIG. 1 shows an example of a manufacturing apparatus
according to Embodiment 1 of the present invention;
[0058] FIGS. 2A and 2B each show an example of a sequence for the
manufacturing apparatus according to Embodiment 1;
[0059] FIG. 3 shows an example of a transfer path for a substrate
according to Embodiment 1;
[0060] FIG. 4 shows another example of the sequence for the
manufacturing apparatus according to Embodiment 1;
[0061] FIG. 5 shows an example of the transfer path for a substrate
according to Embodiment 1;
[0062] FIGS. 6A and 6B each show another example of the sequence
for the manufacturing apparatus according to Embodiment 1;
[0063] FIG. 7 shows an example of a transfer path for two
substrates according to Embodiment 1;
[0064] FIGS. 8A to 8C show an evaporation apparatus according to
Embodiment 2 of the present invention;
[0065] FIGS. 9A and 9B show the evaporation apparatus according to
Embodiment 2 of the present invention;
[0066] FIGS. 10A and 10B show examples of a container according to
Embodiment 3 of the present invention;
[0067] FIGS. 11A and 11B show other examples of the container
according to Embodiment 3 of the present invention;
[0068] FIGS. 12A and 12B show examples of an evaporation source
holder according to Embodiment 3 of the present invention;
[0069] FIG. 13 shows a manufacturing system according to Embodiment
4 of the present invention;
[0070] FIG. 14 shows a transfer container according to Embodiment 4
of the present invention;
[0071] FIGS. 15A and 15B show an evaporation apparatus according to
Embodiment 4 of the present invention;
[0072] FIGS. 16A and 16B show the evaporation apparatus according
to Embodiment 4 of the present invention;
[0073] FIGS. 17A and 17B show a light emitting device according to
Example 1 of the present invention;
[0074] FIGS. 18A and 18B show the light emitting device according
to Example 1 of the present invention;
[0075] FIGS. 19A to 19C show the light emitting device according to
Example 1 of the present invention;
[0076] FIGS. 20A to 20H each show an example of electronic
equipment using the present invention;
[0077] FIG. 21 shows another example of the manufacturing apparatus
according to Embodiment 1 of the present invention; and
[0078] FIG. 22 shows a conventional evaporation apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EXAMPLES
[0079] Hereinafter, embodiments of the present invention will be
described.
Embodiment 1
[0080] FIG. 1 shows an example of a manufacturing apparatus of a
multi-chamber system in which all production processes are
automated from a process of forming a first electrode to a sealing
process.
[0081] The multi-chamber manufacturing apparatus shown in FIG. 1
includes: gates 100a to 100s; a take-out chamber 119; transfer
chambers 104a, 102, 114, and 118; handing-over chambers 105 and
107; a preparation chamber 101; a first film forming chamber 106A;
a second film forming chamber 106B; a third film forming chamber
106C; a fourth film forming chamber 106D; other film forming
chambers 109a, 109b, 113a, and 113b; process chambers 120a and
120b; setting chambers 126A, 126B, 126C, and 126D for installing an
evaporation source; pre-treatment chambers 103a and 103b; a first
sealing chamber 116a; a second sealing chamber 116b; a first stock
chamber 130a; a second stock chamber 130b; cassette chambers 131a
and 131b; a tray putting stage 121; and a washing chamber 122.
[0082] Hereinafter, a description will be made of a procedure for
producing a light emitting device after a substrate to which a
thin-film transistor, an anode (first electrode), and an insulator
covering an end portion of the anode are formed in advance is
loaded into the manufacturing apparatus shown in FIG. 1.
[0083] First, the above-mentioned substrate is set in the cassette
chamber 131a or 131b.
[0084] If the substrate has a large size (for example, 300
mm.times.360 mm), the substrate is set in the cassette chamber 131a
and 131b. If the substrate has a normal size (for example, 127
mm.times.127 mm), the substrate is transferred to the tray putting
stage 121 and plural substrates are set in a tray (having a size
of, for example, 300 mm.times.360 mm).
[0085] Next, the plural substrates each formed with the thin-film
transistor, the anode, and the insulator covering an end portion of
the anode are transferred to the transfer chamber 118, and then
further transferred to the washing chamber 122 to remove impurities
(such as fine particles) from the substrate surfaces by using a
solution. If the substrates are washed in the washing chamber 122,
the substrates are set with the surfaces to be formed with a film
facing downward at the atmospheric pressure.
[0086] Also, before forming a film containing an organic compound,
in order to remove moisture and gas from within the substrates, it
is preferable to perform annealing for degasification in vacuum.
Therefore, the substrates may be transferred to the pretreatment
chambers 103a and 103b each connected to the transfer chamber 118,
to be subjected to annealing therein. Also, if a film containing an
organic compound formed to an unnecessary portion is to be removed,
the substrates are transferred to the pretreatment chambers 103a
and 103b to selectively remove a laminate of organic compound film
layers. The pretreatment chambers 103a and 103b each have plasma
generating means, and generate plasma by exciting one or plural
kinds of gas selected from the group consisting of Ar, H, F, and O,
to thereby perform dry etching. Here, it is shown as an example
that the two pretreatment chambers 103a and 103b are provided to
allow treatment on the two substrates substantially in parallel
with each other.
[0087] Next, the substrates are transferred from the transfer
chamber 118 provided with a substrate transferring mechanism to the
preparation chamber 101. In the manufacturing apparatus of this
embodiment, the preparation chamber 101 has a substrate inverting
mechanism and can invert the substrates appropriately. The
preparation chamber 101 is connected to a vacuum-exhaust process
chamber and preferably set to the atmospheric pressure by
introducing inert gas into the chamber after the chamber is
vacuum-exhausted.
[0088] Next, the substrates are transferred to the transfer chamber
102 connected to the preparation chamber 101. It is preferable that
the transfer chamber 102 be vacuum-exhausted in advance and
maintain vacuum so as to contain as little moisture and oxygen as
possible.
[0089] The above-mentioned vacuum-exhaust process chamber is
provided with a magnetic levitation turbomolecular pump, a
cryopump, or a dry pump. The pump makes it possible for the
transfer chamber connected to the preparation chamber to reach a
vacuum level of 10.sup.-5 to 10.sup.-6 Pa. In addition, reverse
diffusion of impurities from the pump side and the exhaust system
can be controlled. In order not to let impurities enter the
interior of the device, inert gas such as nitrogen or rare gas is
introduced. Used as the gas introduced into the device is one that
is refined to have a high purity by a gas refining machine prior to
introduction to the device interior. Thus, it is necessary to
provide a gas refining machine such that the gas is refined to have
a high purity and, after that, introduced into an evaporation
apparatus. Accordingly, oxygen, water, and other impurities are
removed from within the gas in advance, thereby making it possible
to prevent those impurities from entering the device interior.
[0090] Next, the substrates are transferred from the transfer
chamber 102 to the first forming chamber 106A, the second film
forming chamber 106B, the third film forming chamber 106C, and the
fourth film forming chamber 106D. Then, low-molecular weight
organic compound layers are formed which serve as hole injecting
layers, hole transporting layers, and light emitting layers.
[0091] As overall light emitting elements, organic compound layers
exhibiting single-color (specifically white) light emission or
full-color (specifically red, green, and blue) light emission can
be formed. Here, an example will be described in which the organic
compound layers exhibiting white light emission are formed in the
respective film forming chambers 106A, 106B, 106C, and 106D at the
same time (each film forming process is performed approximately in
parallel).
[0092] Note that in the case where the organic compound layers
exhibiting white light emission are a laminate of light emitting
layers having different light emission colors, the organic compound
layers are broadly divided into two types: a three wavelength type
that includes the primary colors of red, green, and blue and a two
wavelength type that utilizes the relationship between
complementary colors of blue and yellow or blue-green and orange.
Here, an example will be described in which a white light emitting
element is obtained using the three wavelength type.
[0093] First, the respective film forming chambers 106A, 106B,
106C, and 106D will be described. The film forming chambers 106A,
106B, 106C, and 106D each have movable evaporation source holders,
which are prepared in plural numbers. In each of the film forming
chambers, five evaporation source holders are set in the following
states: a first evaporation source holder has aromatic diamine
(referred to as TPD) for forming a white light emitting layer
sealed therein; a second evaporation source holder has p-EtTAZ for
forming a white light emitting layer sealed therein; a third
evaporation source holder has Alq.sub.3 for forming a white light
emitting layer sealed therein; a fourth evaporation source holder
has an EL material sealed therein which is obtained by doping
Alq.sub.3 for forming a white light emitting layer with Nile Red
that is a red light emitting pigment; and a fifth evaporation
source holder has Alq.sub.3 sealed therein.
[0094] It is preferable that EL materials be set in the above film
forming chambers by using the following manufacturing system. That
is, it is preferable that a container (typically a melting pot) in
which an EL material is stored in advance by a material
manufacturer be used to form a film. In addition, it is preferable
that the container be set without being exposed to the atmosphere.
Thus, it is preferable that the melting pot be sealed in a second
container when being shipped from the material manufacturer, and
then be loaded into a film forming chamber while maintaining the
sealed state. It is desirable that the setting chambers 126A, 126B,
126C, and 126D each having vacuum-exhaust means and connected to
the film forming chambers 106A, 106B, 106C, and 106D, respectively,
be set to vacuum or an inert gas atmosphere, and melting pots be
taken out of second containers in the setting chambers and then be
set in the film forming chambers. As a result, a melting pot and an
EL material stored in the melting pot can be protected from
contamination. Note that metal masks may be stocked in the setting
chambers 126A, 126B, 126C, and 126D.
[0095] Next, film forming steps will be described. In the film
forming chamber 106A, a mask is transferred from the setting
chamber described above and set as the need arises. Then, the first
to fifth evaporation source holders start to move sequentially to
perform evaporation to the substrate. More specifically, TPD from
the first evaporation source holder is sublimated by heating and is
deposited by evaporation on the entire surface of the substrate.
After that, p-EtTAZ from the second evaporation source holder is
sublimated, Alq.sub.3 from the third evaporation source holder is
sublimated, Alq.sub.3: Nile Red from the fourth evaporation source
holder is sublimated, and Alq.sub.3 from the fifth evaporation
source holder is sublimated, which are all deposited by evaporation
on the entire surface of the substrate.
[0096] In the case of using an evaporation method, it is preferable
to perform evaporation in the film forming chamber that is
vacuum-exhausted to reach a vacuum level of 5.times.10.sup.-3 Torr
(0.665 Pa) or lower, preferably, 10.sup.-4 to 10.sup.-6 Pa.
[0097] Note that the above-mentioned evaporation source holders
with the EL materials set therein are provided in the respective
film forming chambers, and also in the respective film forming
chambers 106B to 106D, evaporation is performed in the same manner.
In other words, the same film forming process can be performed to
four substrates approximately in parallel. FIG. 7 shows a simple
example of the path along which two of the four substrates are
processed. As a result, even if a given film forming chamber is
undergoing maintenance or cleaning, the film forming process is
possible in the rest of the film forming chambers, thereby reducing
the cycle time for the film formation. Accordingly, the throughput
of the light emitting device can be improved.
[0098] Next, the substrate is transferred from the transfer chamber
102 to the handing-over chamber 105, and further transferred from
the handing-over chamber 105 to the transfer chamber 104a without
being exposed to the atmosphere.
[0099] Next, a transfer mechanism set in the transfer chamber 104a
is used to transfer the substrate to the film forming chamber 109a
or the film forming chamber 109b, and then a cathode is formed to
the substrate. The cathode may be formed by laminating two cathodes
(lower layer and upper layer). The cathode (lower layer) is formed
of an extremely thin metal film (MgAg, MgIn, AlLi, CaN, or like
other alloy film, or a film formed by co-evaporation of aluminum
and an element that belongs to Group 1 or 2 in the periodic table)
formed by evaporation using resistance heating. The cathode (upper
layer) is formed of a transparent conductive film (an indium tin
oxide alloy (ITO) film, an indium oxide-zinc oxide alloy
(In.sub.2O.sub.3--ZnO) film a zinc oxide (ZnO) film, or the like)
formed by sputtering. Therefore, it is preferable that a film
forming chamber for forming a thin metal film be arranged in the
manufacturing apparatus.
[0100] Through the above steps, a light emitting element having a
laminate structure as shown in FIGS. 17A and 17B is formed.
[0101] Next, without being exposed to the atmosphere, the substrate
is transferred from the transfer chamber 104a to the film forming
chamber 113a or 113b, and then a protective film consisting of a
silicon nitride film or a silicon nitroxide film is formed to the
substrate. Here, the film forming chambers 113a and 113b each
include a silicon target, a silicon oxide target, or a silicon
nitride target. For example, a silicon nitride film can be formed
by using the silicon target and setting the atmosphere in the film
forming chamber to a nitrogen atmosphere or an atmosphere
containing nitrogen and argon. FIG. 1 shows an example system
provided with the two film forming chambers 113a and 113b such that
a protective film can be formed to two substrates approximately in
parallel.
[0102] Next, without being exposed to the atmosphere, the substrate
formed with a light emitting device is transferred from the
transfer chamber 104a to the handing-over chamber 107, and further
transferred from the handing-over chamber 107 to the transfer
chamber 114. Then, the substrate formed with a light emitting
device is transferred from the transfer chamber 114 to the first
sealing chamber 116a or the second sealing chamber 116b. Note that
in the first sealing chamber 116a and the second sealing chamber
116b, a sealing member for bonding substrates to each other later
or for sealing a substrate is formed. FIG. 1 shows an example
system provided with the two sealing chambers 116a and 116b such
that a bonding process can be performed to two substrates
approximately in parallel.
[0103] A sealing substrate is set in the first stock chamber 130a
or the second stock chamber 130b from the outside for preparation.
Note that in order to remove moisture and other impurities, it is
preferable that the sealing substrate be subjected to annealing in
vacuum in advance, for example, within the first stock chamber 130a
or the second stock chamber 130b. If the sealing member for bonding
the sealing substrate and the substrate on which the light emitting
element is formed is formed on the sealing substrate, the sealing
member is formed in the first stock chamber 130a or the second
stock chamber 130b, and the sealing substrate on which the sealing
member is formed is then transferred to the first sealing chamber
116a or the second sealing chamber 116b. Note that the sealing
substrate may be provided with a desiccant in the first sealing
chamber 116a or the second sealing chamber 116b. Also, the first
sealing chamber 130a and the second sealing chamber 130b may be
stocked with an evaporation mask to be used at the time of
evaporation.
[0104] Next, in order to perform degasification to the substrate
provided with the light emitting device, after performing annealing
in vacuum or in an inert gas atmosphere, the sealing substrate
provided with the sealing member and the substrate formed with the
light emitting device are bonded to each other. Also, an enclosed
space is filled with nitrogen or inert gas. Note that here, the
example of forming the sealing member on the sealing substrate is
shown. However, there is no particular limitation and the sealing
member may be formed on the substrate formed with the light
emitting element.
[0105] Next, the pair of bonded substrates are irradiated with UV
light by a UV ray irradiation mechanism provided in the sealing
chamber 116a, 116b to thereby cure the sealing member. Note that a
UV-curable and thermoset resin is used here as the sealing member.
However, there is no particular limitation as long as an adhesive
is used as the sealing member, and such a resin as one curable by
only a UV ray may be used.
[0106] Further, instead of filling the enclosed space with inert
gas, a resin may be filled therein. In the case of a downward
emission type, no light transmits through the cathode, so that the
material for the resin to be filled are not particularly limited
and the UV-curable resin or an opaque resin may be used. However,
in the case of an upward emission type, a UV ray transmits through
the cathode to cause damage to the EL layer, so that the UV-curable
resin cannot be used. Thus, in the case of an upward emission type,
it is preferable to use a transparent thermoset resin as the resin
to be filled.
[0107] Next, the pair of bonded substrates are transferred from the
sealing chamber 116a, 116b to the transfer chamber 114, and then
transferred from the transfer chamber 114 to the take-out chamber
119 to be taken out thereof.
[0108] Further, after being taken out of the take-out chamber 119,
the sealing member is cured by heat treatment. In the case of using
the upward emission type and filling the enclosed space with the
thermoset resin, the thermoset resin can be cured simultaneously
with the heat treatment for curing the sealing member.
[0109] As described above, the use of the manufacturing apparatus
shown in FIG. 1 prevents a light emitting element from being
exposed to the atmosphere before the light emitting element is
completely sealed in an enclosed space. As a result, a light
emitting device having high reliability can be produced. Note that
the transfer chamber 114 alternates between vacuum and a nitrogen
atmosphere at the atmospheric pressure. However, it is desirable
that the transfer chambers 102, 104a, and 108 maintain vacuum all
the time.
[0110] Note that, although not shown in the figures, a control
drive unit is provided which controls the path along which
substrates are moved to individual process chambers, to thereby
realize a fully automatic system.
[0111] Also, it is possible to load a substrate formed with a
transparent conductive film as the anode into the manufacturing
apparatus shown in FIG. 1, and form a light emitting element
(having a structure in which light emission caused in a layer
containing an organic compound is taken out from the transparent
anode toward a TFT; hereinafter referred to as downward emission
structure) that emits light in the direction opposite to that of
the laminate structure described above.
[0112] In the case where both the anode and the cathode are
composed of a transparent or translucent material, it is also
possible to form a structure in which light emission caused in the
layer containing the organic compound is taken out toward both the
upper surface and the lower surface (hereinafter referred to as
double-sided emission structure).
[0113] Further, FIG. 21 shows an example of a manufacturing
apparatus provided with two take-out chambers because plural
take-out chambers become necessary in the case where elements are
produced by simultaneously processing two substrates in different
sizes in parallel. A mask stock chamber and a coating chamber are
also provided in FIG. 21. Note that in FIG. 21, the same reference
numerals as those in FIG. 1 are used.
[0114] In FIG. 21, reference numeral 100t denotes a gate, 1003 the
coating chamber, 1013 the mask stock chamber, and reference
numerals 1019a and 1019b denote the take-out chambers.
[0115] Note that the mask stock chamber 1013 is stocked with
evaporation masks to be used at the time of evaporation. The
evaporation masks are appropriately transferred to each film
forming chamber when performing evaporation, and then set therein.
In particular, it is difficult to stock the mask having a large
area in the setting chamber, so that it is preferable to separately
provide the mask stock chamber as shown in FIG. 21. Also, the mask
stock chamber 1013 may be stocked with not only the evaporation
masks but also, for example, substrates.
[0116] Further, in the coating chamber 1003, a layer containing a
high-molecular weight material may be formed by an ink jet method
or a spin coating method. For example, an aqueous solution of
poly(ethylene dioxythiophene)/poly(styrene sulfonic acid)
(PEDOT/PSS) acting as a hole injecting layer (an anode buffer
layer), an aqueous solution of polyaniline/camphor sulfonic acid
(PANI/CSA), PTPDES, Et-PTPDEK, PPBA or the like may be coated over
the entire surface of the first electrode (anode) and then
subjected to baking.
[0117] Further, the PEDOT/PSS film formed by the spin coating
method covers the entire surface. Accordingly, it is preferable to
selectively remove portions of the film that cover end surfaces and
perimeter of the substrate, a terminal portion, a region where a
cathode and a lower wiring are connected to each other, and the
like. For example, it is preferable that the removal is performed
by O.sub.2 ashing or the like using a mask in the pretreatment
chamber 103a.
Embodiment 2
[0118] FIGS. 8A to 8C show a film forming system featured in moving
a substrate and an evaporation source relative to each other. FIG.
8A is a sectional view in X direction (a section taken along a
dotted line A-A'), FIG. 8B is a sectional view in Y direction (a
section taken along a dotted line B-B') and FIG. 8C is a top view.
Further, FIGS. 8A, 8B and 8C show the evaporation system in the
midst of evaporation.
[0119] The film forming system shown in FIGS. 8A to 8C is
characterized in that in an evaporation system, an evaporation
source holder installed with a container filled with an evaporation
material is moved by a certain pitch relative to a substrate or the
substrate is moved by a certain pitch relative to the evaporation
source. Further, it is preferable to move the evaporation source
holder by a certain pitch to overlap ends (skirts) of a sublimated
evaporation material.
[0120] Although a single or a plurality of the evaporation source
holders may be constituted, when the evaporation source holders are
provided for respective laminated films of EL layers, evaporation
can be carried out efficiently and continuously. Further, a single
or a plurality of containers may be installed at the evaporation
source holder and a plurality of containers filled with the same
evaporation material may be installed. Further, when containers
having different evaporation materials are arranged, a film can be
formed at a substrate in a state of mixing the sublimated
evaporation materials (this is referred to as common
evaporation).
[0121] In FIGS. 8A to 8C, a film forming chamber 11 includes a
substrate holder 12, an evaporation source holder 17 installed with
an evaporation shutter 15, means for moving the evaporation source
holder (not illustrated) and means for producing a low pressure
atmosphere. Further, the film forming chamber 11 is installed with
a substrate 13 and an evaporation mask 14. Further, alignment of
the evaporation mask may be confirmed by using a CCD camera (not
illustrated). The evaporation source holder 17 is installed with a
container filled with an evaporation material 18. The film forming
chamber 11 is vacuumed to a vacuum degree of 5.times.10.sup.-3 Torr
(0.665 Pa) or lower, preferably, 10.sup.-4 through 10.sup.-6 Pa by
the means for producing the low pressure atmosphere.
[0122] Further, in evaporation, the evaporation material is
previously sublimated (vaporized) by resistance heating and
scattered in a direction of the substrate 13 by opening the shutter
15 in evaporation. An evaporated evaporation material 19 is
scattered in an upward direction and is selectively vapor-deposited
on the substrate 13 by passing an opening portion provided at the
evaporation mask 14. Further, preferably, a speed of film
formation, a moving speed of the evaporation holder and opening and
closing of the shutter are controlled by a control unit such as a
personal computer. The evaporation rate of the evaporation source
holder can be controlled by the moving speed.
[0123] Further, although not illustrated, evaporation can be
carried out while measuring a film thickness of a deposited film by
a quartz oscillator provided at the film forming chamber 11. When
the film thickness of the deposited film is measured by using the
quartz oscillator, a change in mass of a film deposited to the
quartz oscillator can be measured as a change in the resonance
frequency.
[0124] In the evaporation system shown in FIGS. 8A to 8C, in
evaporation, a distance d of an interval between the substrate 13
and the evaporation source holder 17 can be reduced to,
representatively, 30 cm or smaller, preferably, 20 cm or smaller,
further preferably, 5 cm through 15 cm to thereby significantly
promote an efficiency of utilizing the evaporation material and
throughput.
[0125] In the evaporation system, the evaporation source holder 17
is constituted by a container (representatively, crucible), a
heater arranged on an outer side of the container via a uniformly
heating member, an insulating layer provided on an outer side of
the heater, an outer cylinder containing these, a cooling pipe
wound around an outer side of the outer cylinder and the
evaporation shutter 15 for opening and closing an opening portion
of the outer cylinder including an opening portion of a crucible.
Further, the evaporation source holder 17 may be a container
capable of being carried in a state of fixing the heater to the
container. Further, the container is formed by a material of a
sintered body of BN, a composite sintered body of BN and AlN,
quartz or a graphite capable of withstanding high temperature, high
pressure and low pressure.
[0126] Further, the evaporation source holder 17 is provided with a
mechanism movable in X direction or Y direction at inside of the
film forming chamber 11 while maintaining a horizontal state. In
this case, the evaporation source holder 17 is made to move in
zigzag on a two-dimensional plane as shown by FIG. 9A or FIG. 9B.
Further, a pitch of moving the evaporation source holder 17 may
pertinently be matched to an interval between insulators. Further,
insulators 10 are arranged in a stripe shape to cover end portions
of first electrodes 21.
[0127] Further, in FIGS. 9A and 9B, timings of starting to move the
evaporation source holders A, B, C and D may be after stopping or
before stopping preceding ones of the evaporation source holders.
For example, with setting an organic material capable of hole
transporting at the evaporation holder A, an organic material
serving as an light emitting layer at the evaporation holder B, an
organic material capable of electron transporting at the
evaporation holder C and a material serving as a cathode buffer at
the evaporation holder D, it is possible to continuously laminate
these material layers in a same chamber. Further, when a succeeding
one of the evaporation source holder starts moving before
solidifying a vapor-deposited film, in an EL layer having a
laminated layers structure, a region mixed with evaporation
materials (mixed region) may be formed at an interface of
respective films.
[0128] According to the invention of moving the substrate and the
evaporation source holders A, B, C and D relative to each other in
this way, small-sized formation of the device can be achieved
without needing to prolong a distance between the substrate and the
evaporation source holder. Further, since the evaporation system is
small-sized, adherence of the sublimated evaporation material to
the inner wall or the adherence preventive shield at inside of the
film forming chamber is reduced and the evaporation material can be
utilized without waste. Further, according to the evaporation
method of the invention, it is not necessary to rotate the
substrate and therefore, the evaporation system capable of dealing
with a large area substrate can be provided. Further, according to
the invention of moving the evaporation source holder in the X axis
direction and the Taxis direction relative to the substrate, the
vapor-deposited film can uniformly be formed.
[0129] Further, it is not necessarily needed that an organic
compound provided at the evaporation source holder is one or one
kind thereof but may be a plurality of kinds thereof. For example,
other than one kind of a material provided as a luminescent organic
compound at the evaporation source holder, other organic compound
which can be a dopant (dopant material) may be provided along
therewith. It is preferable to design an organic compound layer to
be vapor-deposited to constitute by a host material and a
luminescent material (dopant material) having excitation energy
lower than that of the host material such that the excitation
energy of the dopant becomes lower than excitation energy of a hole
transporting region and excitation energy of an electron
transporting layer. Thereby, diffusion of a molecular exciter of
the dopant can be prevented and the dopant can effectively be made
to emit light. Further, when the dopant is a material of a carrier
trap type, an efficiency of recombining carriers can also be
promoted. Further, the invention includes a case in which a
material capable of converting triplet excitation energy to
luminescence is added to a mixing region as a dopant. Further, in
forming the mixing region, a concentration gradient may be provided
to the mixing region.
[0130] Further, when a plurality of organic compounds are provided
at a single evaporation source holder, it is preferable for
evaporating directions to be skew to intersect at a position of an
object to be deposited such that the organic compounds are mixed
together. Further, in order to carry out common evaporation, the
evaporation source holder may be provided with four kinds of
evaporation materials (for example, two kinds of host materials as
evaporation material A, two kinds of dopant materials as
evaporation material b). Further, when a pixel size is small (or,
an interval between respective insulators is narrow), a film can
finely be formed by dividing inside of a container in four and
carrying out common evaporation for subjecting respective
pertinently to evaporation.
[0131] Further, since the interval distance d between the substrate
13 and the evaporation source holder 17 is narrowed to,
representatively, 30 cm or smaller, preferably, 5 cm through 15 cm,
there is a concern of heating also the evaporation mask 14.
Therefore, it is preferable for the evaporation mask 14 to use a
metal material having a low thermal expansion rate which is
difficult to deform by heat (for example, a high melting point
metal such as tungsten, tantalum, chromium, nickel or molybdenum or
an alloy including these elements, a material such as stainless
steel, inconel, Hastelloy). For example, a low thermal expansion
alloy having 42% of nickel and 58% of iron or the like is pointed
out. Further, in order to cool the evaporation mask to be heated,
the evaporation mask may be provided with a mechanism of
circulating a cooling medium (cooling water, cooling gas).
[0132] Further, in order to clean a deposited substance adhered to
the mask, it is preferable to generate a plasma at inside of the
film forming chamber by plasma generating means to vaporize the
deposited substance adhered to the mask to vent the vapor to
outside of the film forming chamber. For that purpose, a mask is
separately provided with an electrode and a high frequency power
source 20 is connected to either one of them.
[0133] Further, the film forming chamber includes gas introducing
means for introducing one kind or a plurality of kinds of gases
selected from the group consisting of Ar, H, F, NF.sub.3, and O and
venting means for venting the deposited substance vaporized. By the
above-described constitution, inside of the film forming chamber
can be cleaned without being in contact with the atmosphere in
maintenance.
[0134] Cleaning can be performed as follows, the atmosphere in a
chamber is substituted by nitrogen, and is vacuum exhausted, and a
high frequency power supply (13.56 MHz) can be connected with
either the mask or the electrode so that a plasma is generated the
mask and the electrode (a substrate shutter, not illustrated).
Then, argon and hydrogen are introduced to the chamber in
respective flow rate of 30 sccm, and the atmosphere in the chamber
are stabilized, an RF electric power of 800 W is applied to
generate a plasma, thereby the mask and inner wall of the chamber
can be cleaned.
[0135] Further, the film forming chamber 11 is connected with a
vacuuming chamber for vacuuming inside of the film forming chamber.
The vacuum processing chamber is provided with a turbo-molecular
pump of a magnetic levitation type, a cryopump or a dry pump.
Thereby, the ultimate vacuum degree of the film forming chamber 11
can be made to be 10.sup.-5 through 10.sup.-6 Pa and inverse
diffusion of an impurity from a pump side and an venting system can
be controlled. In order to prevent an impurity from being
introduced into the film forming chamber 11, as a gas to be
introduced, an inert gas of nitrogen or rare gas is used. There are
used the gases to be introduced which are highly purified by a gas
refiner before being introduced into the device. Therefore, it is
necessary to provide the gas refiner such that the gas is highly
purified and thereafter introduced into the film forming chamber
11. Thereby, an impurity of oxygen, water or the like included in
the gas can previously be removed and therefore, the impurities can
be prevented from being introduced into the film forming chamber
11.
[0136] Further, the substrate holder 12 is provided with a
permanent magnet for fixing the evaporation mask comprising a metal
with the magnetic force and also fixing the substrate 13 interposed
therebetween. Although an example of bringing the evaporation mask
into close contact with the substrate 13 is shown here, a substrate
holder or an evaporation mask holder fixed with an interval to some
degree therebetween may pertinently be provided.
[0137] According to the film forming chamber having the mechanism
of moving the evaporation source holder as described above, it is
not necessary to prolong the distance between the substrate and the
evaporation source holder and the evaporation film can uniformly be
formed.
Embodiment 3
[0138] Here, a detailed description will be given of constitutions
of a container for filling an evaporation material and an
evaporation source holder at a surrounding thereof in reference to
FIGS. 10A and 10B as follows. Further, FIGS. 10A and 10B show a
state of an open shutter.
[0139] FIG. 10A shows a sectional view of a surrounding of one
container installed at an evaporation source holder 304 illustrated
with heating means 303 provided at the evaporation source holder, a
power source 307 of the heating means, an evaporation material 302
of the container, a filter 305 provided at inside of the container
and a shutter 306 arranged above an opening portion provided at an
upper portion of the container. As the heating means 303,
resistance heating, high frequency or laser may be used,
specifically, an electric coil may be used.
[0140] Further, the evaporation material 302 heated by the heating
means 303 is sublimated and the sublimated material 302 rises
upwardly from the opening portion of the container. At this
occasion, the sublimated material having a size equal to or larger
than a certain constant amount (mesh of filter) cannot pass the
filter 305 provided at inside of the container, returns into the
container and is sublimated again. Further, the filter 305 may be
formed by a highly conductive material and heated by heating means
(not illustrated). By the heating, the evaporation material can be
prevented from being solidified and adhered to the filter.
[0141] By the container having the constitution provided with such
a filter, the evaporation material having an even size is
vapor-deposited and therefore, a speed of film formation can be
controlled and a uniform film thickness can be provided and uniform
evaporation without nonuniformity can be carried out. Naturally,
when uniform evaporation without nonuniformity can be carried out,
it is not necessarily needed to provide a filter. Further, a shape
of the container is not limited to that in FIG. 10A.
[0142] Next, an explanation will be given of a container filled
with an evaporation material having a constitution different from
that of FIG. 10A in reference to FIG. 10B.
[0143] FIG. 10B is illustrated with a container 311 installed at an
evaporation holder, an evaporation material 312 at inside of the
container, first heating means 313 provided at the evaporation
source holder, a power source 318 of the first heating means, a
shutter 317 arranged above an opening portion of the container, a
plate 316 provided above the opening portion, second heating means
314 provided to surround the filter and a power source 319 of
second heating means.
[0144] Further, the evaporation material 312 heated by the first
heating means 313 is sublimated and the sublimated evaporation
material rises upwardly from the opening portion of the container
311. At this occasion, the sublimated material having a size equal
to or larger than a certain constant amount cannot pass an interval
between the plate 316 provided above the opening portion of the
container and the second heating means 314, impinges on the plate
316 and returns to inside of the container. Further, since the
plate 316 is heated by the second heating means 314, the
evaporation material can be prevented from solidifying and adhering
to the plate 316. Further, it is preferable to form the plate 316
by a highly conductive material. Further, a filter may be provided
in place of the plate.
[0145] Further, as heating temperature (T.sub.1) by the first
heating means 313, a temperature higher than a sublimating
temperature (T.sub.A) of the evaporation material is applied, a
heating temperature (T.sub.2) by the second heating means 314 may
be lower than that of the first heating means. This is because once
sublimated evaporation material is easy to sublimate and therefore,
the evaporation material is sublimated without applying the actual
sublimating temperature. That is, respective heating temperatures
may establish T.sub.i>>T.sub.2>T.sub.A.
[0146] By such a container having a constitution of providing the
heating means around the plate, the evaporation material having an
even size is sublimated, further, the sublimated material passes a
vicinity of the heating means and therefore, adherence of the
evaporation material to the plate is reduced, further, the speed of
film formation can be controlled and therefore a uniform film
thickness can be provided and uniform evaporation without
nonuniformity can be carried out. Naturally, when the uniform
evaporation without nonuniformity can be carried out, it is not
necessarily needed to provide the plate. Further, the shape of the
container is not limited to those in FIGS. 10A and 10B but, for
example, the container may be provided with shapes as shown by
FIGS. 11A and 11B.
[0147] FIG. 11A shows an example of providing heating means 402 at
an evaporation source holder 404 illustrating sectional views of
examples of shapes of containers 403 and 405 in each of which an
opening portion of the container is narrowed toward an upper side
thereof. Further, after filling a refined evaporation material in a
container having a wide opening portion, the shapes of the
container 403 or 405 shown in FIG. 11A may be constituted by using
a lid or the like. Further, when a diameter of the opening portion
of the container narrowed toward the upper side is constituted by
the size of the evaporation material intended to form, an effect
similar to that of a filter can be achieved.
[0148] Further, FIG. 11B shows examples of providing heating means
412 at containers. Although shapes of the containers 413 and 415
are similar to those of FIG. 11A, the heating means 412 are
provided at the containers per se. Further, power sources of the
heating means may be designed to be brought into an ON state at a
stage of being installed to evaporation source holders. By such a
constitution of providing the heating means at the container per
se, heat can be applied sufficiently to an evaporation material
even in the case of a container having an opening portion in a
shape which is difficult to heat.
[0149] Next, a specific constitution of an evaporation source
holder will be explained in reference to FIGS. 12A and 12B. FIGS.
12A and 12B show enlarged views of evaporation source holders.
[0150] FIG. 12A shows a constitution example of providing four
containers 501 filled with an evaporation material to an
evaporation source holder 502 in a shape of a lattice and providing
shutters 503 above the respective containers and FIG. 12B shows a
constitution example of providing four containers 511 filled with
an evaporation material to an evaporation source holder 512 in a
linear shape and providing shutters 513 above the respective
containers.
[0151] A plurality of the containers 501 or 511 filled with the
same material may be installed at the evaporation source holder 502
or 512 illustrated in FIG. 12A or 12B or a single one of the
container may be installed at the evaporation source holder.
Further, common evaporation may be carried out by installing
containers filled with different evaporation materials (for
example, host material and guest material). Further, as described
above, the evaporation material is sublimated by heating the
container and a film is formed at the substrate.
[0152] Further, as shown by FIG. 12A or 12B, it may be controlled
whether the film is formed by the sublimated evaporation material
by providing the shutter 503 or 513 above each container. Further,
only a single one of the shutter may be provided above all of the
containers. Further, by the shutter, it can be reduced to sublimate
and scatter an unnecessary evaporation material without stopping to
heat the evaporation source holder which does not form the film,
that is, the evaporation source holder being at standby. Further,
the constitution of the evaporation source holder is not limited to
those of FIGS. 12A and 12B but may pertinently be designed by a
person for embodying the invention.
[0153] By the above-described evaporation source holder and
container, the evaporation material can efficiently be sublimated,
further, the film is formed in a state in which the size of the
evaporation material is even and therefore, a uniform evaporation
film without nonuniformity is formed. Further, a plurality of
evaporation materials can be installed at the evaporation source
holder and therefore, common evaporation can easily be carried out.
Further, an aimed EL layer can be formed in one operation without
moving the film forming chamber for each film of the EL layer.
Embodiment 4
[0154] An explanation will be given, with reference to FIG. 13, of
a system of a fabricating method of filling a refined evaporation
material in the above-described container, carrying the container
and thereafter installing the container directly at an evaporation
system which is a film forming device, to carry out
evaporation.
[0155] FIG. 13 illustrates a manufacturer, representatively, a
material manufacturer 618 (representatively, material manufacturer)
for producing and refining an organic compound material which is an
evaporation material and a manufacturer (representatively,
production factory) 619 of a luminescent device which is a
manufacturer of a luminescent device having an evaporation
system.
[0156] First, an order 610 is carried out from the luminescent
device manufacturer 619 to the material manufacturer 618. Based on
the order 610, the material manufacturer 618 refines to sublimate
an evaporation material and fills an evaporation material 612 in a
shape of a powder refined in high purity to a first container 611.
Thereafter, the material manufacturer 618 isolates the first
container from the atmosphere such that an extra impurity is not
adhered to inside or outside thereof, and contains the first
container 611 in second containers 621a and 621b to hermetically
seal for preventing the first container 611 from being contaminated
at inside of the clean environment chamber. In hermetically sealing
the second containers 621a and 621b, at inside of the containers it
is preferable to be vacuum or to be filled with an inert gas of
nitrogen or the like. Further, it is preferable to clean the first
container 611 and the second containers 621a and 621b before
refining or containing the evaporation material 612 with an ultra
high purity. Further, although the second containers 621a and 621b
may be package films having barrier performance for blocking oxygen
or moisture from mixing thereinto, in order to be able to take out
the containers automatically, it is preferable that the second
containers are constituted by stout containers having light
blocking performance in a shape of a cylinder or a shape of a
box.
[0157] Thereafter, the first container 611 is carried (617) from
the material manufacturer 618 to the luminescent device
manufacturer 619 in a state of being hermetically sealed by the
second containers 621a and 621b.
[0158] At the luminescent device manufacturer 619, the first
container 611 is directly introduced into a vacuumable processing
chamber 613 in a state of being hermetically sealed in the second
containers 621a and 621b. Further, the processing chamber 613 is an
evaporation system installed with heating means 614 and substrate
holding means (not illustrated) at inside thereof.
[0159] Thereafter, inside of the processing chamber 613 is vacuumed
to bring about a clean state in which oxygen or moisture is reduced
as less as possible, thereafter, without breaking the vacuum, the
first container 611 is taken out from the second containers 621a
and 621b, the first container 611 is installed in contact with the
heating means 614 and an evaporation source can be prepared.
Further, an object to be deposited (here, substrate) 615 is
installed at the processing chamber 613 to be opposed to the first
container 611.
[0160] Successively, an evaporation film 616 is formed on a surface
of the object to be deposited 615 by applying heat to the
evaporation material by the heating means 614. The evaporation film
616 provided in this way does not include an impurity and when a
luminescent element is finished by using the evaporation film 616,
high reliability and high brightness can be realized.
[0161] Further, after forming the film, the evaporation material
remaining at the first container 611 may be sublimated to refine at
the luminescent device manufacturer 619. After forming the film,
the first container 611 is installed at the second containers 621a
and 621b, taken out from the processing chamber 613 and carried to
a refining chamber for sublimating to refine the evaporation
material. There, the remaining evaporation material is sublimated
to refine and the evaporation material in a shape of a powder
refined at high purity is filled into a separate container.
Thereafter, in a state of being hermetically sealed in the second
container, the evaporation material is carried to the processing
chamber 613 to carry out evaporation processing. At this occasion,
it is preferable that a relationship among temperature (T3) for
refining the remaining evaporation material, temperature (T4)
elevated at a surrounding of the evaporation material and
temperature (T5) at a surrounding of the evaporation material which
is sublimated to refine satisfy T3>T4>T5. That is, in the
case of sublimating to refine the material, when temperature is
lowered toward a side of the container for filling the evaporation
material to be sublimated to refine, convection is brought about
and the material can be sublimated to refine efficiently. Further,
the refining chamber for sublimating to refine the evaporation
material may be provided in contact with the processing chamber 613
and the evaporation material which has been sublimated to refine
may be carried without using the second container for hermetically
sealing the evaporation material.
[0162] As described above, the first container 611 is installed in
the evaporation chamber which is the processing chamber 613 without
being brought into contact with the atmosphere at all to enable to
carry out evaporation while maintaining the purity at the stage of
containing the evaporation material 612 by the material
manufacturer. Therefore, according to the invention, a fully
automated fabricating system promoting the throughput can be
realized and an integrated closed system capable of avoiding the
impurity from mixing to the evaporation material 812 refined at the
material manufacturer 618 can be realized. Further, the evaporation
material 612 is directly contained in the first container 611 by
the material mater based on the order and therefore, only a
necessary amount thereof is provided to the luminescent device
manufacturer and the comparatively expensive evaporation material
can efficiently be used. Further, the first container and the
second container can be reutilized to amount to a reduction in
cost.
[0163] A specific explanation will be given of a mode of the
container to be carried in reference to FIG. 14 as follows. A
second container divided into an upper portion (621a) and a lower
portion (621b) used for transportation includes fixing means 706
provided at an upper portion of the second container for fixing a
first container, a spring 705 for pressing the fixing means, a gas
introducing port 708 provided at a lower portion of the second
container for constituting a gas path for maintaining the second
container being depressurized, an O ring 707 for fixing the upper
container 621a and the lower container 621b and a retaining piece
702. The first container 611 filled with the refined evaporation
material is installed in the second container. Further, the second
container may be formed by a material including stainless steel and
the first container may be formed by a material including
titanium.
[0164] At the material manufacturer, the refined evaporation
material is filled in the first container 611. Further, the upper
portion 621a and the lower portion 621b of the second container are
matched via the O ring 707, the upper container 621a and the lower
container 621b are fixed by the retaining piece 702, and the first
container 611 is hermetically sealed at inside of the second
container. Thereafter, inside of the second container is
depressurized via the gas introducing port 708 and is replaced by a
nitrogen atmosphere and the first container 611 is fixed by the
fixing means 706 by adjusting the spring 705. A desiccant may be
installed at inside of the second container. When inside of the
second container is maintained in vacuum, in a low pressure or in
nitrogen atmosphere in this way, even a small amount of oxygen or
water can be prevented from adhering to the evaporation
material.
[0165] The first container 611 is carried to the luminescent device
manufacturer 619 under the state and is directly installed to the
processing chamber 613. Thereafter, the evaporation material is
sublimated by heating and the evaporation film 616 is formed.
[0166] Next, an explanation will be given of a mechanism of
installing the first container 611 which is carried by being
hermetically sealed in the second container to a film forming
chamber 806 in reference to FIGS. 15A and 15B and FIGS. 16A and
16B. Further, FIGS. 15A and 15B and FIGS. 16A and 16B show the
first container in the midst of transportation.
[0167] FIG. 15A illustrates to a top view of an installing chamber
805 including a base 804 for mounting the first container or the
second container, an evaporation source holder 803, and carrying
means 802 for carrying the base 804, the evaporation source holder
803 and the first container, and FIG. 15B illustrates a perspective
view of the installing chamber. Further, the installing chamber 805
is arranged to be contiguous to the film forming chamber 806 and
the atmosphere of the installing chamber can be controlled by means
for controlling the atmosphere via a gas introducing port. Further,
the carrying means of the invention is not limited to a
constitution of pinching a side face of the first container to
carry as illustrated in FIGS. 15A and 15B but may be constructed by
a constitution of pinching (picking) the first container at upper
part thereof to carry.
[0168] The second container is arranged to such an installing
chamber 805 above the base 804 in a state of disengaging the
retaining piece 702. Successively, inside of the installing chamber
805 is brought into a decompressed state by means for controlling
the atmosphere. When pressure at inside of the installing chamber
and pressure at inside of the second container become equal to each
other, there is brought about a state of being capable of opening
the second container easily. Further, the upper portion 621a of the
second container is removed and the first container 611 is
installed in the evaporation source holder 803 by the carrying
means 802. Further, although not illustrated, a portion for
installing the removed upper portion 621a is pertinently provided.
Further, the evaporation source holder 803 is moved from the
installing chamber 805 to the film forming chamber 806.
[0169] Thereafter, by heating means provided at the evaporation
source holder 803, the evaporation material is sublimated and the
film starts to be formed. In forming the film, when a shutter (not
illustrated) provided at the evaporation source holder 803 is
opened, the sublimated evaporation material is scattered to the
direction of the substrate and the vapor-deposited onto the
substrate to form the luminescent layer (including hole
transporting layer, hole injecting layer, electron transporting
layer and electron injecting layer).
[0170] Further, after finishing evaporation, the evaporation source
holder 803 returns to the installing chamber 805 and the first
container 611 installed at the evaporation source holder 803 by the
carrying means 802 is transferred to the lower container (not
illustrated) of the second container installed at the base 804 and
is hermetically sealed by the upper container 621a. At this
occasion, it is preferable that the first container, the upper
container 621a and the lower container are hermetically sealed by a
combination by which the containers have been carried. Under the
state, the installing chamber 805 is brought under the atmospheric
pressure and the second container is taken out from the installing
chamber, fixed with the retaining piece 702 and is carried to the
material manufacturer 618.
[0171] Next, an explanation will be given of a mechanism of
installing a plurality of first containers carried by being
hermetically sealed by the second containers to a plurality of the
evaporation source holders, which is different from those of FIGS.
15A and 15B in reference to FIGS. 16A and 16B.
[0172] FIG. 16A illustrates a top view of an installing chamber 905
including a base 904 for mounting the first container or the second
container, a plurality of evaporation source holders 903, a
plurality of carrying means 902 for carrying the first containers
and a rotating base 907 and FIG. 16B illustrates a perspective view
of the installing chamber 905. Further, the installing chamber 905
is arranged to be contiguous to a film forming chamber 906 and the
atmosphere of the installing chamber can be controlled by means for
controlling the atmosphere via a gas introducing port.
[0173] By the rotating base 907 and the plurality of carrying means
902, operation of installing the plurality of first containers 611
to the plurality of evaporation source holders 903 and transferring
the plurality of first containers 611 from the plurality of
evaporation source holders finished with film formation to the base
904 can efficiently be carried out. At this occasion, it is
preferable to install the first container 611 to the second
container which has been carried.
[0174] Further, in order to carry the evaporation source holder for
starting evaporation and the evaporation source holder finished
with evaporation efficiently, the rotating base 907 may be provided
with a rotating function. In addition, the structure of the
rotating base 907 is not limited to the above one, as far as the
rotating base 907 has a function of moving to the right and lift
directions, when the rotating base approaches to the evaporation
holders arranged in the film forming chamber 906, a plurality of
the first containers may be provided at the evaporation holders by
the carrying means 902
[0175] According to an evaporation film formed by the
above-described evaporation system, an impurity can be reduced to
an extreme and when a luminescent element is finished by using the
evaporation film, high reliability and brightness can be realized.
Further, by such a fabricating system, the container filled by the
material manufacturer can be installed directly to the evaporation
system and therefore, oxygen or water can be prevented from
adhering to the evaporation material and further ultrahigh purity
formation of the luminescent element in the future can be dealt
with. Further, by refining the container having the remaining
evaporation material again, waste of the material can be
eliminated. Further, the first container and the second container
can be reutilized and the low cost formation can be realized.
[0176] The present invention constituted by the above structure
will be described in more detail with examples shown below.
EXAMPLES
[0177] Examples of the present invention are described thereinafter
based on the drawings. In addition, in all drawings used for the
description of the examples, same portions are given common
symbols, and the repetitive descriptions thereof are omitted.
Example 1
[0178] In this example, an example of forming TFT on a substrate
having an insulating surface and forming an EL element (light
emitting element) is shown in FIG. 17. A cross-sectional view of
one 1 that is connected to an EL element in a pixel portion is
shown in this example.
[0179] A base insulating film 201 is formed by a lamination of
insulating films such as a silicon oxide film, a silicon nitride
film or a silicon oxynitride film on a substrate 200 having an
insulating surface. Although the base insulating film 201 herein
uses a two-layer structure, it may use a structure having a single
layer or two layers or more of the insulating films. The first
layer of the base insulating film is a silicon oxynitride film
formed to have a thickness of 10 to 200 nm (preferably 50 to 100
nm) by plasma CVD using a reaction gas of SiH.sub.4, NH.sub.3 and
N.sub.2O. Herein, a silicon oxynitride film is formed (composition
ratio: Si=32%, O=27%, N=24% and H=17%) having a film thickness of
50 nm. The second layer of the base insulating film is a silicon
oxynitride film formed to have a thickness 50 to 200 nm (preferably
100 to 150 nm) by plasma CVD using a reaction gas of SiH.sub.4 and
N.sub.2O. Herein, a silicon oxynitride film is formed (composition
ratio: Si=32%, O=59%, N=7% and H=2%) having a film thickness of 100
nm.
[0180] Subsequently, a semiconductor layer is formed on the base
insulating film 201. The semiconductor layer is formed as follows:
an amorphous semiconductor film is formed by known means (a
sputtering, an LPCVD, a plasma CVD, or the like), then, the film is
crystallized by a known crystallization method (a laser
crystallization method, a thermal crystallization method or a
thermal crystallization method using a catalyst such as nickel),
and then, the crystalline semiconductor film is patterned into a
desired form. This semiconductor layer is formed in a thickness of
25 to 80 nm (preferably 30 to 60 nm). The material of the
crystalline semiconductor film, although not limited in material,
is preferably formed of silicon or a silicon-germanium alloy.
[0181] In the case of forming a crystalline semiconductor film by a
laser crystallizing process, it is possible to use an excimer laser
of a pulse-oscillation or continuous-oscillation type, a YAG laser,
or an YVO.sub.4 laser. In the case of using such laser, preferably
used is a method that the laser light emitted from a laser
oscillator is condensed by an optical system into a linear form to
be irradiated onto the semiconductor film. The condition of
crystallization is to be appropriately selected by those who
implement the invention. In the case of using an excimer laser,
pulse oscillation frequency is 30 Hz and laser energy density is
100 to 400 mJ/cm.sup.2 (typically 200 to 300 mJ/cm.sup.2).
Meanwhile, in the case of using a YAG laser, preferably its second
harmonic is used and pulse oscillation frequency is 1 to 10 kHz and
laser energy density is 300 to 600 mJ/cm.sup.2 (typically 350 to
500 mJ/cm.sup.2). The laser light focused linear to a width of 100
to 1000 .mu.m, e.g. 400 .mu.m, is irradiated throughout the
substrate entirety, whereupon the overlap ratio of linear laser
beam may be taken 50 to 98%.
[0182] Then, the surface of the semiconductor layer is cleaned by
an etchant containing a hydrogen fluoride, to form a gate
insulating film 202 covering the semiconductor layer. The gate
insulating film 202 is formed by an insulating film containing
silicon having a thickness of 40 to 150 nm by the use of plasma CVD
or sputtering. In this example, a silicon oxynitride film is formed
(composition ratio: Si=32%, O=59%, N=7% and H=2%) to have a
thickness of 115 nm by plasma CVD. Of course, the gate insulating
film 202 is not limited to a silicon oxynitride film but may be
made in a single layer or a lamination of layers of insulating
films containing other form of silicon.
[0183] After cleaning the surface of the gate insulating film 202,
a gate electrode 210 is formed.
[0184] Then, a p-type providing impurity element (such as B),
herein, adequate amounts of boron is added to the semiconductor to
form a source region 211 and a drain region 212. After the addition
of the impurity element, heating process, intense light radiation
or laser irradiation is made in order to activate the impurity
element. Simultaneously with activation, restoration is possible
from the plasma damage to the gate insulating film or from the
plasma damage at the interface between the gate insulating film and
the semiconductor layer. Particularly, it is extremely effective to
irradiate the second harmonic of a YAG laser at a main or back
surface thereby activating the impurity element in an atmosphere at
room temperature to 300.degree. C. YAG laser is preferable
activating means since it requires a few maintenances.
[0185] In the subsequent process, after hydrogenation is carried
out, an insulator 213a made from an organic or inorganic material
(for example, from a photosensitive organic resin) is formed, then,
an aluminum nitride film, an aluminum oxynitride film shown as
AlN.sub.xO.sub.y, or a first protection film 213b made from a
silicon nitride film are formed. The film shown as AlN.sub.xO.sub.y
is formed by introducing oxygen, nitrogen, or rear gas from the gas
inlet system by RF sputtering using a target made of AlN or Al. The
content of nitrogen in the AlN.sub.xO.sub.y film may be in the
range of at least several atom %, or 2.5 to 47.5 atom %, and the
content of oxygen may be in the range of at most 47.5 atom %,
preferably, less than 0.01 to 20 atom %. A contact hole is formed
therein reaching the source region 211 or drain region 212. Next, a
source electrode (wiring) 215 and a drain electrode 214 are formed
to complete a TFT (p-channel TFT). This TFT will control the
current that is supplied to OLED (Organic Light Emitting
Device).
[0186] Also, the present invention is not limited to the TFT
structure of this example, but, if required, may be in a lightly
doped drain (LDD) structure having an LDD region between the
channel region and the drain region (or source region). This
structure is formed with a region an impurity element is added with
light concentration between the channel formation region and the
source or drain region formed by adding an impurity element with
high concentration, which is called an LDD region. Furthermore, it
may be in, what is called, a GOLD (Gate-drain Overlapped LDD)
structure arranging an LDD region overlapped with a gate electrode
through a gate insulating film. It is preferable that the gate
electrode is formed in a lamination structure and etched to have a
different taper angle of an upper gate electrode and a lower gate
electrode to form an LDD region and a GOLD region in a
self-aligning manner using the gate electrode as a mask.
[0187] Meanwhile, although explanation herein was by using the
p-channel TFT, it is needless to say that an n-channel TFT can be
formed by using an n-type impurity element (P, As, etc.) in place
of the p-type impurity element.
[0188] Though a top gate TFT is described as an example in this
example, the present invention can be applied irrespective of TFT's
structure. For example, the present invention can be applied to a
bottom gate (reverse stagger) TFT and a forward stagger TFT.
[0189] Subsequently, in the pixel portion, a first electrode 217 in
contact with a connecting electrode in contact with the drain
region is arranged in matrix shape. This first electrode 217 serves
as an anode or a cathode of the light-emitting element. Then, an
insulator (generally referred to as a bank, a partition, a barrier,
a mound, or the like) 216 that covers the end portion of the first
electrode 217 is formed. For the insulator 216, a photosensitive
organic resin is used. In the case of using a negative type
photosensitive acrylic resin is used as a material of the insulator
216, for example, the insulator 216 may be preferably prepared such
that the upper end portion of the insulator 216 has a curved
surface having a first curvature radius and the lower end portion
of the insulator has a curved surface having a second curvature
radius. Each of the first and second curvature radiuses may be
preferably in the range of 0.2 .mu.m to 3 .mu.m. Furthermore, a
layer 218 containing an organic compound is formed in the pixel
portion, and a second electrode 219 is then formed thereon to
complete an EL element. This second electrode 219 serves as a
cathode or an anode of the EL element.
[0190] The insulator 216 that covers the end portion of the first
electrode 217 may be covered with a second protective film formed
of an aluminum nitride film, an aluminum nitride oxide film, or a
silicon nitride film.
[0191] For instance, an example of using a positive type
photosensitive acrylic resin as a material of the insulator 216 is
shown in FIG. 17B. The insulator 316a has a curved surface having a
curvature radius only the upper end thereof. Furthermore, the
insulator 316a is covered with a second protective film 316b formed
of an aluminum nitride film, an aluminum nitride oxide film, or a
silicon nitride film.
[0192] For instance, when the first electrode 217 is used as an
anode, the material of the first electrode 217 may be a metal
(i.e., Pt, Cr, W, Ni, Zn, Sn, or In) having a large work function.
The end portion of such an electrode 217 is covered with the
insulator (generally referred to as a bank, a partition, a barrier,
a mound, or the like) 216 or 316, then, a vacuum-evaporation is
carried out moving an evaporation source along with the insulator
216 or 316 by using the evaporation system shown in Embodiments 1
to 3. For example, a film forming chamber is vacuum-exhausted until
the degree of vacuum reaches 5.times.10.sup.-3 Torr (0.665 Pa) or
less, preferably 10.sup.-4 to 10.sup.-6 Pa, for vacuum-evaporation.
Prior to vacuum-evaporation, the organic compound is vaporized by
resistance heating. The vaporized organic compound is scattered on
the substrate as the shutter is opened for vacuum-evaporation. The
vaporized organic compound is scattered upward, then, deposited on
the substrate through an opening formed in a metal mask. A light
emitting layer (including a hole transporting layer, a hole
injection layer, an electron transporting layer, and an electron
injection layer) is formed.
[0193] In the case that a layer containing an organic compound is
formed that emits white luminescence in its entirety by
vacuum-evaporation, it can be formed by depositing each light
emitting layer. For instance, an Alq.sub.3 film, an Alq.sub.3 film
partially doped with Nile red which is a red light emitting
pigment, a p-EtTAZ film, and a TPD (aromatic diamine) film are
layered in this order to obtain white light.
[0194] In case of using vacuum-evaporation, as shown in Embodiment
3, a container (typically a melting pot) in which an EL material
that a vacuum-evaporation material is stored in advance by a
material manufacturer is set in a film forming chamber. Preferably,
the melting pot is set in the film forming chamber while avoiding
contact with the air. The melting pot shipped from a material
manufacturer is preferably sealed in a second container during
shipment and is introduced into a film forming chamber in that
state. Desirably, a chamber having vacuum exhaust means is
connected to the film forming chamber, the melting pot is taken out
of the second container in vacuum or in an inert gas atmosphere in
this chamber, and then the melting pot is set in the film forming
chamber. In this way, the melting pot and the EL material stored in
the melting pot are protected from contamination.
[0195] The second electrode 219 comprises a laminate structure of a
metal (e.g., Li, Mg, or Cs) having a small work function; and a
transparent conductive film (made of an indium tin oxide (ITO)
alloy, an indium zinc oxide alloy (In.sub.2O.sub.3--ZnO), zinc
oxide (ZnO), or the like) on the thin film. For attaining a
low-resistance cathode, an auxiliary electrode may be provided on
the insulator 216 or 316. The light-emitting element thus obtained
emits white luminescence. Here, the example in which the layer 218
containing the organic compound is formed by vacuum-evaporation has
been described. According to the present invention, however, it is
not limited to a specific method and the layer 218 may be formed
using a coating method (a spin coating method, an ink jet
method).
[0196] In this example, an example of depositing layers made from
low molecular material as an organic compound layer is described
though, both high molecular materials and low molecular materials
may also be deposited.
[0197] It can be thought that there are two types of structures of
an active matrix light emitting device having TFT in terms of
radiating direction of luminescence. One is a structure that
luminescence generated in a light emitting element can be observed
passing through the second electrode, and can be manufactured using
the above-mentioned steps.
[0198] Another structure is that luminescence generated in the
light emitting element is irradiated into the eyes of the observer
after passing through the first electrode, it is preferable that
the first electrode 217 may be prepared using a material having a
translucency. For instance, when the first electrode 217 is
provided as an anode, a transparent conductive film (made of an
indium tin oxide (ITO) alloy, an indium zinc oxide alloy
(In.sub.2O.sub.3--ZnO), zinc oxide (ZnO), or the like) is used for
a material of the first electrode 217 and the end portion thereof
is covered with the insulator (generally referred to as a bank, a
partition, a barrier, a mound, or the like) 216, followed by
forming the layer 218 containing an organic compound. On this
layer, furthermore, a second electrode 219 formed of a metal film
(i.e., an alloy of MgAg, MgIn, AlLi, CaF.sub.2, CaN, or the like,
or a film formed by a co-vacuum-evaporation of an element of Group
I and Group II in the periodic table and aluminum) is formed as a
cathode. Here, a resistive heating method using vacuum-evaporation
is used for the formation of a cathode, so that the cathode can be
selectively formed using a vacuum-evaporation mask.
[0199] After forming the second electrode 219 by the steps
described above, a seal substrate is laminated using a sealing
material to encapsulate the light-emitting element formed on the
substrate 200.
[0200] Here, an appearance view of an active matrix type
light-emitting device is described with reference to FIGS. 18A and
18B. Further, FIG. 18A is a top view showing the light emitting
apparatus and FIG. 18B is a sectional view constituted by cutting
FIG. 18A by a line A-A'. A source signal side driving circuit 1101,
a pixel portion 1102, and a gate signal line driving circuit 1103
are formed on a substrate 1110. An inner side surrounded by a seal
substrate 1104, the sealing material 1105, and the substrate 1110
constitutes a space 1107.
[0201] Further, a wiring 1108 for transmitting signals inputted to
the source signal side driving circuit 1101 and the gate signal
side driving circuit 1103 receives a video signal or a clock signal
from FPC (flexible printed circuit) 1109 for constituting an
external input terminal. Although only FPC is illustrated here, the
FPC may be attached with a printed wiring substrate (PWB). The
light emitting apparatus in the specification includes not only a
main body of the light emitting apparatus but also a state in which
FPC or PWB is attached thereto.
[0202] Next, a sectional structure will be explained in reference
to FIG. 18B. Driver circuits and the pixel portion are formed over
a substrate 1110 and here, the source signal line driving circuit
1101 as the driver circuit and the pixel portion 1102 are
shown.
[0203] Further, the source signal line driving circuit 1101 is
formed with a CMOS circuit combined with an n-channel type TFT 1123
and a p-channel type TFT 1124. Further, TFT for forming the driver
circuit may be formed by a publicly-known CMOS circuit, PMOS
circuit or NMOS circuit. Further, although according to this
example, a driver integrated type formed with the driver circuits
over the substrate is shown, the driver integrated type is not
necessarily be needed and the driver circuits can be formed not
over the substrate but at outside thereof.
[0204] Further, the pixel portion 1102 is formed of a plurality of
pixels each including a switching TFT 1111, a current controlling
TFT 1112, and a first electrode (anode) 1113 electrically connected
to a drain of the current controlling TFT 1112.
[0205] Further, an insulating layer 1114 is formed at both ends of
the first electrode (anode) 1113 and an organic compound layer 1115
is formed on the first electrode (anode) 1113. The organic compound
layer 1115 is formed by moving an evaporation source along with the
insulating film 1114 by using the device shown in Embodiments 1 and
2. Further, a second electrode (cathode) 1116 is formed over the
organic compound layer 1115. As a result, a light-emitting element
1118 comprising the first electrode (anode) 1112, the organic
compound layer 1115 and the second electrode (cathode) 1116 is
formed. Here, the light-emitting element 1118 shows an example of
white color luminescence and therefore, provided with the color
filter comprising a coloring layer 1131 and a light-shielding layer
1132 (for simplification, overcoat layer is not illustrated
here).
[0206] In FIGS. 19A to 19C, a color filter is formed at the side of
a seal substrate 1104 since it is the structure that light emitted
from a light emitting element is observed through the second
electrode, however, in case of the structure that light emitted
from a light emitting element is observed through the first
electrode, a color filter is formed at the side of the substrate
1110.
[0207] The second electrode (cathode) 1116 functions also as a
wiring common to all the pixels and electrically connected to FPC
1109 via the connection wiring 1108. The third electrode (auxiliary
electrode) 1117 is formed on the insulating layer 1114 to realize
to make the second electrode have a low resistance.
[0208] Further, in order to encapsulate the light-emitting element
1118 formed over the substrate 1110, the seal substrate 1104 is
pasted by the sealing material 1105. Further, a spacer comprising a
resin film may be provided for ensuring an interval between the
seal substrate 1104 and the light-emitting element 1118. Further,
the space 1107 on the inner side of the sealing material 1105 is
filled with an inert gas of nitrogen or the like. Further, it is
preferable to use epoxy species resin for the sealing material
1105. Further, it is preferable that the sealing material 1105 is a
material for permeating moisture or oxygen as less as possible.
Further, the inner portion of the space 1107 may be included with
the substance having an effect of absorbing oxygen or moisture.
[0209] Further, according to the example, as a material for
constituting the seal substrate 1104, other than glass substrate or
quartz substrate, a plastic substrate comprising FRP
(Fiberglass-Reinforced Plastics), PVF (polyvinyl fluoride), Mylar,
polyester or acrylic resin can be used. Further, it is possible to
adhere the seal substrate 1104 by using the sealing material 1105
and thereafter seal to cover a side face (exposed face) by a
sealing material.
[0210] By encapsulating the light-emitting element as described
above, the light-emitting element can completely be blocked from
outside and a substance for expediting to deteriorate the organic
compound layer such as moisture or oxygen can be prevented from
invading from outside. Therefore, the highly reliable
light-emitting device can be provided.
[0211] Further, this example can be freely combined with
Embodiments 1 to 4.
Example 2
[0212] Given as examples of electronic apparatuses that employ the
light emitting device manufactured in accordance with the present
invention are video cameras, digital cameras, goggle type displays
(head mounted displays), navigation systems, audio reproducing
devices (such as car audio and audio components), laptop computers,
game machines, portable information terminals (such as mobile
computers, cellular phones, portable game machines, and electronic
books), and image reproducing devices equipped with recording media
(specifically, devices with a display device that can reproduce
data in a recording medium such as a digital versatile disk (DVD)
to display an image of the data). A wide viewing angle is important
particularly for portable information terminals because their
screens are often slanted when they are looked at. Therefore it is
preferable for portable information terminals to employ the light
emitting device using the light emitting element. Specific examples
of these electronic apparatuses are shown in FIGS. 20A to 20H.
[0213] FIG. 20A shows a light emitting device including a case
2001, a support base 2002, a display unit 2003, speaker units 2004,
a video input terminal 2005, etc. The light emitting device
manufactured in accordance with the present invention can be
applied to the display unit 2003. In addition, the light emitting
device shown in FIG. 20A can be completed by the present invention.
Since the light emitting device having the light emitting element
is of self-luminous type, the device does not need a backlight and
can make a thinner display unit than that of a liquid crystal
display device. The light emitting device refers to all light
emitting devices for displaying information, including ones for
personal computers, for TV broadcasting reception, and for
advertisement.
[0214] FIG. 20B shows a digital still camera including a main body
2101, a display unit 2102, an image receiving unit 2103, operation
keys 2104, an external connection port 2105, a shutter 2106, etc.
The light emitting device manufactured in accordance with the
present invention can be applied to the display unit 2102. The
digital camera shown in FIG. 16B can be completed by the present
invention.
[0215] FIG. 20C shows a laptop computer including a main body 2201,
a case 2202, a display unit 2203, a keyboard 2204, an external
connection port 2205, a pointing mouse 2206, etc. The light
emitting device manufactured in accordance with the present
invention can be applied to the display unit 2203. The laptop
computer shown in FIG. 20C can be completed by the present
invention.
[0216] FIG. 20D shows a mobile computer including a main body 2301,
a display unit 2302, a switch 2303, operation keys 2304, an
infrared port 2305, etc. The light emitting device manufactured in
accordance with the present invention can be applied to the display
unit 2302. The mobile computer shown in FIG. 20D can be completed
by the present invention.
[0217] FIG. 20E shows a portable image reproducing device equipped
with a recording medium (a DVD player, to be specific). The device
includes a main body 2401, a case 2402, a display unit A 2403, a
display unit B 2404, a recording medium (DVD or the like) reading
unit 2405, operation keys 2406, speaker units 2407, etc. The
display unit A 2403 mainly displays image information whereas the
display unit B 2404 mainly displays text information. The light
emitting device manufactured in accordance with the present
invention can be applied to the display units A 2403 and B 2404.
The image reproducing device equipped with a recording medium also
includes home-video game machines. The DVD player shown in FIG. 20E
can be completed by the present invention.
[0218] FIG. 20F shows a goggle type display (head mounted display)
including a main body 2501, display units 2502, and arm units 2503.
The light emitting device manufactured in accordance with the
present invention can be applied to the display units 2502. The
goggle type display shown in FIG. 20F can be completed by the
present invention.
[0219] FIG. 20G shows a video camera including a main body 2601, a
display unit 2602, a case 2603, an external connection port 2604, a
remote control receiving unit 2605, an image receiving unit 2606, a
battery 2607, an audio input unit 2608, operation keys 2609 etc.
The light emitting device manufactured in accordance with the
present invention can be applied to the display unit 2602. The
video camera shown in FIG. 200 can be completed by the present
invention.
[0220] FIG. 20H shows a cellular phone including a main body 2701,
a case 2702, a display unit 2703, an audio input unit 2704, an
audio output unit 2705, operation keys 2706, an external connection
port 2707, an antenna 2708, etc. The light emitting device
manufactured in accordance with the present invention can be
applied to the display unit 2703. If the display unit 2703 displays
white letters on a black background, the cellular phone consumes
less power. The cellular phone shown in FIG. 20H can be completed
by the present invention.
[0221] If a brighter luminance of luminescence materials becomes
valuable in the future, the light emitting device can be used in
front or rear projectors by enlarging outputted light that contains
image information through a lens or the like and projecting the
light.
[0222] These electronic apparatuses now display with increasing
frequency information sent through electronic communication lines
such as the Internet and CATV (cable television), especially,
animation information. Since the luminescence materials have very
fast response speed, the light emitting device is suitable for
moving images.
[0223] According to the present invention, there can be provided a
manufacturing apparatus including the plural film forming chambers
for performing the evaporation process, which are arranged in a
row. Accordingly, the film forming processes are performed in the
plural film forming chambers approximately in parallel, thereby
improving the throughput of the light emitting device and allowing
the reduction of a processing time per substrate.
[0224] Further, according to the present invention, even though the
processing number of substrates is slightly reduced, the
maintenance of one or plural film forming chambers is possible
without temporarily stopping the production line.
* * * * *