U.S. patent application number 15/774783 was filed with the patent office on 2019-11-28 for method and apparatus for producing flexible oled device.
The applicant listed for this patent is Sakai Display Products Corporation. Invention is credited to Katsuhiko KISHIMOTO, Kazunobu MAMENO, Kohichi TANAKA.
Application Number | 20190363264 15/774783 |
Document ID | / |
Family ID | 62236423 |
Filed Date | 2019-11-28 |
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United States Patent
Application |
20190363264 |
Kind Code |
A1 |
KISHIMOTO; Katsuhiko ; et
al. |
November 28, 2019 |
METHOD AND APPARATUS FOR PRODUCING FLEXIBLE OLED DEVICE
Abstract
According to a flexible OLED device production method of the
present disclosure, after an intermediate region (30i) and flexible
substrate regions (30d) of a plastic film (30) of a multilayer
stack (100) are divided from one another, the interface between the
flexible substrate regions (30d) and a glass base (10) is
irradiated with laser light. The multilayer stack (100) is
separated into a first portion (110) and a second portion (120)
while the multilayer stack (100) is in contact with a stage (210).
The first portion (110) includes a plurality of OLED devices (1000)
which are in contact with the stage (210). The OLED devices (1000)
include a plurality of functional layer regions (20) and the
flexible substrate regions (30d). The second portion (120) includes
the glass base (10) and the intermediate region (30i). The step of
irradiating with the laser light includes the first laser light
scanning for scanning the interface in a first direction with the
laser light in the form of a line beam, and the second laser light
scanning for scanning the interface in a second direction with the
laser light. In each of the first and second laser light scanning,
the irradiation intensity is modulated such that the irradiation
intensity for at least part of the interface between the
intermediate region (30i) and the glass base (10) is lower than the
irradiation intensity for the interface between the flexible
substrate regions (30d) and the glass base (10).
Inventors: |
KISHIMOTO; Katsuhiko;
(Osaka, JP) ; TANAKA; Kohichi; (Osaka, JP)
; MAMENO; Kazunobu; (Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sakai Display Products Corporation |
Sakai-shi, Osaka |
|
JP |
|
|
Family ID: |
62236423 |
Appl. No.: |
15/774783 |
Filed: |
October 26, 2017 |
PCT Filed: |
October 26, 2017 |
PCT NO: |
PCT/JP2017/038787 |
371 Date: |
May 9, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 27/3244 20130101;
H05B 33/10 20130101; G09F 9/30 20130101; H01L 2251/5338 20130101;
H01L 51/5253 20130101; H01L 51/003 20130101; H01L 51/56 20130101;
H01L 51/0097 20130101; H01L 2227/326 20130101; H01L 2251/566
20130101; H05B 33/02 20130101 |
International
Class: |
H01L 51/00 20060101
H01L051/00; H01L 27/32 20060101 H01L027/32; H01L 51/52 20060101
H01L051/52; H01L 51/56 20060101 H01L051/56 |
Claims
1. A method for producing a flexible OLED device, comprising:
providing a multilayer stack which has a first surface and a second
surface, the multilayer stack including a glass base which defines
the first surface, a plurality of functional layer regions each
including a TFT layer and an OLED layer, a synthetic resin film
provided between the glass base and the plurality of functional
layer regions and bound to the glass base, the synthetic resin film
including a plurality of flexible substrate regions respectively
supporting the plurality of functional layer regions and an
intermediate region surrounding the plurality of flexible substrate
regions, and a protection sheet which covers the plurality of
functional layer regions and which defines the second surface;
dividing the intermediate region and respective ones of the
plurality of flexible substrate regions of the synthetic resin film
from one another; irradiating an interface between the synthetic
resin film and the glass base with laser light; and separating the
multilayer stack into a first portion and a second portion by
increasing a distance from a stage to the glass base while the
second surface of the multilayer stack is kept in contact with the
stage, wherein the first portion of the multilayer stack includes a
plurality of OLED devices which are in contact with the stage, and
the plurality of OLED devices respectively include the plurality of
functional layer regions and include the plurality of flexible
substrate regions of the synthetic resin film, the second portion
of the multilayer stack includes the glass base and the
intermediate region of the synthetic resin film, irradiating the
interface between the plurality of flexible substrate regions of
the synthetic resin film and the glass base with the laser light
includes first laser light scanning for scanning the interface in a
first direction parallel to the interface with the laser light in
the form of a line beam which is transverse to the first direction,
and second laser light scanning for scanning the interface in a
second direction which is parallel to the interface and different
from the first direction with the laser light in the form of a line
beam which is transverse to the second direction, and in each of
the first and second laser light scanning, an irradiation intensity
of the laser light is modulated such that an irradiation intensity
of the laser light for at least part of an interface between the
intermediate region of the synthetic resin film and the glass base
is lower than an irradiation intensity of the laser light for the
interface between the plurality of flexible substrate regions of
the synthetic resin film and the glass base.
2. The method of claim 1, wherein in each of the first and second
laser light scanning, an irradiation intensity of the laser light
is lower than a threshold level which is necessary for delaminating
the plurality of flexible substrate regions of the synthetic resin
film from the glass base through a single scanning cycle, and a sum
of irradiation intensities of the laser light in the first and
second laser light scanning is higher than the threshold level.
3. The method of claim 1, wherein providing the multilayer stack
includes providing a delamination layer between the glass base and
the synthetic resin film.
4. The method of claim 3, wherein the delamination layer is made of
a metal or a semiconductor.
5. The method of claim 1, wherein the laser light is a line beam
extending in a direction parallel to a peripheral edge of the glass
base, and irradiating the interface between the synthetic resin
film and the glass base with the laser light includes moving an
irradiation region on the interface which is to be irradiated with
the laser light in another direction which is transverse to an
extending direction of the line beam.
6. The method of claim 5, wherein the at least part of the
interface between the intermediate region of the synthetic resin
film and the glass base includes two parallel stripe regions
extending along the peripheral edge of the glass base.
7. The method of claim 2, wherein the at least part of the
interface between the intermediate region of the synthetic resin
film and the glass base includes at least one middle stripe region
which is parallel to the stripe regions.
8. The method of claim 1, wherein the at least part of the
interface between the intermediate region of the synthetic resin
film and the glass base has a width which is not less than 50% of a
width of the intermediate region.
9. The method of claim 1, wherein the at least part of the
interface between the intermediate region of the synthetic resin
film and the glass base has a width which is not less than 1
mm.
10. The method of claim 1 further comprising, after separating the
multilayer stack into the first portion and the second portion,
sequentially or concurrently performing a process on the plurality
of OLED devices which are in contact with the stage.
11. The method of claim 10, wherein the process includes any of
attaching a dielectric and/or electrically-conductive film to each
of the plurality of OLED devices, cleaning or etching each of the
plurality of OLED devices, and mounting an optical part and/or an
electronic part to each of the plurality of OLED devices.
12. An apparatus for producing a flexible OLED device, comprising:
a stage for supporting a multilayer stack which has a first surface
and a second surface, the multilayer stack including a glass base
which defines the first surface, a plurality of functional layer
regions each including a TFT layer and an OLED layer, a synthetic
resin film provided between the glass base and the plurality of
functional layer regions and bound to the glass base, the synthetic
resin film including a plurality of flexible substrate regions
respectively supporting the plurality of functional layer regions
and an intermediate region surrounding the plurality of flexible
substrate regions, and a protection sheet which covers the
plurality of functional layer regions and which defines the second
surface, the intermediate region and respective ones of the
plurality of flexible substrate regions of the synthetic resin film
being divided from one another; and a lift-off light irradiation
unit for irradiating with laser light an interface between the
synthetic resin film and the glass base in the multilayer stack
supported by the stage, wherein the lift-off light irradiation unit
includes first laser light scanning for scanning the interface in a
first direction parallel to the interface with the laser light in
the form of a line beam which is transverse to the first direction,
and second laser light scanning for scanning the interface in a
second direction which is parallel to the interface and different
from the first direction with the laser light in the form of a line
beam which is transverse to the second direction, and in each of
the first and second laser light scanning, an irradiation intensity
of the laser light is modulated such that an irradiation intensity
of the laser light for at least part of an interface between the
intermediate region of the synthetic resin film and the glass base
is lower than an irradiation intensity of the laser light for the
interface between the plurality of flexible substrate regions of
the synthetic resin film and the glass base.
13. The apparatus of claim 12, wherein in each of the first and
second laser light scanning, an irradiation intensity of the laser
light is lower than a threshold level which is necessary for
delaminating the plurality of flexible substrate regions of the
synthetic resin film from the glass base through a single scanning
cycle, and a sum of irradiation intensities of the laser light in
the first and second laser light scanning is higher than the
threshold level.
14. The apparatus of claim 12, further comprising an actuator for
increasing a distance from the stage to the glass base while the
stage is kept in contact with the second surface of the multilayer
stack, thereby separating the multilayer stack into a first portion
and a second portion, wherein the first portion of the multilayer
stack includes a plurality of OLED devices which are in contact
with the stage, and the plurality of OLED devices respectively
include the plurality of functional layer regions and include the
plurality of flexible substrate regions of the synthetic resin
film, and the second portion of the multilayer stack includes the
glass base and the intermediate region of the synthetic resin film.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a method and apparatus for
producing a flexible OLED device.
BACKGROUND ART
[0002] A typical example of the flexible display includes a film
which is made of a synthetic resin such as polyimide (hereinafter,
referred to as "plastic film"), and elements supported by the
plastic film, such as TFTs (Thin Film Transistors) and OLEDs
(Organic Light Emitting Diodes). The plastic film functions as a
flexible substrate. The flexible display is encapsulated with a gas
barrier film (encapsulation film) because an organic semiconductor
layer which is a constituent of the OLED is likely to deteriorate
due to water vapor.
[0003] Production of the above-described flexible display is
carried out using a glass base on which a plastic film is formed
over the upper surface. The glass base functions as a support
(carrier) for keeping the shape of the plastic film flat during the
production process. Elements such as TFTs and OLEDs, a gas barrier
film, and the other constituents are formed on the plastic film,
whereby the structure of a flexible OLED device is realized while
it is supported by the glass base. Thereafter, the flexible OLED
device is delaminated from the glass base and gains flexibility.
The entirety of a portion in which elements such as TFTs and OLEDs
are arrayed can be referred to as "functional layer region".
[0004] According to the prior art, a sheet-like structure including
a plurality of flexible OLED devices is delaminated from a glass
base, and thereafter, optical parts and other constituents are
mounted to this sheet-like structure. Thereafter, the sheet-like
structure is divided into a plurality of flexible devices. This
dividing is realized by, for example, laser beam irradiation.
[0005] Patent Document No. 1 discloses the method of irradiating
the interface between each flexible OLED device and the glass base
with laser light (lift-off light) in order to delaminate each
flexible OLED device from the glass base (supporting substrate).
According to the method disclosed in Patent Document No. 1, after
irradiation with the lift-off light, respective flexible OLED
devices are divided from one another, and each of the flexible OLED
devices is delaminated from the glass base.
CITATION LIST
Patent Literature
[0006] Patent Document No. 1: Japanese Laid-Open Patent Publication
No. 2014-48619
SUMMARY OF INVENTION
Technical Problem
[0007] According to the conventional production method, the
dividing by means of laser beam irradiation is carried out after
expensive parts, for example, encapsulation film, polarizer, and/or
heat radiation sheet, are mounted to a sheet-like structure
including a plurality of flexible OLED devices. Therefore,
unnecessary portions divided by laser beam irradiation, i.e.,
portions which are not to be constituents of a final OLED device,
are quite useless. Also, there is a problem that, after being
delaminated from the glass base, it is difficult to handle a
plurality of flexible OLED devices which have no rigidity.
[0008] The present disclosure provides a method and apparatus for
producing a flexible OLED device which are capable of solving the
above-described problems.
Solution to Problem
[0009] A flexible OLED device production method of the present
disclosure includes, in an exemplary embodiment, providing a
multilayer stack which has a first surface and a second surface,
the multilayer stack including a glass base which defines the first
surface, a plurality of functional layer regions each including a
TFT layer and an OLED layer, a synthetic resin film provided
between the glass base and the plurality of functional layer
regions and bound to the glass base, the synthetic resin film
including a plurality of flexible substrate regions respectively
supporting the plurality of functional layer regions and an
intermediate region surrounding the plurality of flexible substrate
regions, and a protection sheet which covers the plurality of
functional layer regions and which defines the second surface;
dividing the intermediate region and respective ones of the
plurality of flexible substrate regions of the synthetic resin film
from one another; irradiating an interface between the synthetic
resin film and the glass base with laser light; and separating the
multilayer stack into a first portion and a second portion by
increasing a distance from a stage to the glass base while the
second surface of the multilayer stack is kept in contact with the
stage, wherein the first portion of the multilayer stack includes a
plurality of OLED devices which are in contact with the stage, and
the plurality of OLED devices respectively include the plurality of
functional layer regions and include the plurality of flexible
substrate regions of the synthetic resin film, the second portion
of the multilayer stack includes the glass base and the
intermediate region of the synthetic resin film, irradiating the
interface between the plurality of flexible substrate regions of
the synthetic resin film and the glass base with the laser light
includes first laser light scanning for scanning the interface in a
first direction parallel to the interface with the laser light in
the form of a line beam which is transverse to the first direction,
and second laser light scanning for scanning the interface in a
second direction which is parallel to the interface and different
from the first direction with the laser light in the form of a line
beam which is transverse to the second direction, and in each of
the first and second laser light scanning, an irradiation intensity
of the laser light is modulated such that an irradiation intensity
of the laser light for at least part of an interface between the
intermediate region of the synthetic resin film and the glass base
is lower than an irradiation intensity of the laser light for the
interface between the plurality of flexible substrate regions of
the synthetic resin film and the glass base.
[0010] In one embodiment, in each of the first and second laser
light scanning, an irradiation intensity of the laser light is
lower than a threshold level which is necessary for delaminating
the plurality of flexible substrate regions of the synthetic resin
film from the glass base through a single scanning cycle, and a sum
of irradiation intensities of the laser light in the first and
second laser light scanning is higher than the threshold level.
[0011] In one embodiment, providing the multilayer stack includes
providing a delamination layer between the glass base and the
synthetic resin film.
[0012] In one embodiment, the delamination layer is made of a metal
or a semiconductor.
[0013] In one embodiment, the laser light is a line beam extending
in a direction parallel to a peripheral edge of the glass base, and
irradiating the interface between the synthetic resin film and the
glass base with the laser light includes moving an irradiation
region on the interface which is to be irradiated with the laser
light in another direction which is transverse to an extending
direction of the line beam.
[0014] In one embodiment, the at least part of the interface
between the intermediate region of the synthetic resin film and the
glass base includes two parallel stripe regions extending along the
peripheral edge of the glass base.
[0015] In one embodiment, the at least part of the interface
between the intermediate region of the synthetic resin film and the
glass base includes at least one middle stripe region which is
parallel to the stripe regions.
[0016] In one embodiment, the at least part of the interface
between the intermediate region of the synthetic resin film and the
glass base has a width which is not less than 50% of a width of the
intermediate region.
[0017] In one embodiment, the at least part of the interface
between the intermediate region of the synthetic resin film and the
glass base has a width which is not less than 1 mm.
[0018] In one embodiment, the method further includes, after
separating the multilayer stack into the first portion and the
second portion, sequentially or concurrently performing a process
on the plurality of OLED devices which are in contact with the
stage.
[0019] In one embodiment, the process includes any of attaching a
dielectric and/or electrically-conductive film to each of the
plurality of OLED devices, cleaning or etching each of the
plurality of OLED devices, and mounting an optical part and/or an
electronic part to each of the plurality of OLED devices.
[0020] A flexible OLED device production apparatus of the present
disclosure includes, in an exemplary embodiment, a stage for
supporting a multilayer stack which has a first surface and a
second surface, the multilayer stack including a glass base which
defines the first surface, a plurality of functional layer regions
each including a TFT layer and an OLED layer, a synthetic resin
film provided between the glass base and the plurality of
functional layer regions and bound to the glass base, the synthetic
resin film including a plurality of flexible substrate regions
respectively supporting the plurality of functional layer regions
and an intermediate region surrounding the plurality of flexible
substrate regions, and a protection sheet which covers the
plurality of functional layer regions and which defines the second
surface, the intermediate region and respective ones of the
plurality of flexible substrate regions of the synthetic resin film
being divided from one another; and a lift-off light irradiation
unit for irradiating with laser light an interface between the
synthetic resin film and the glass base in the multilayer stack
supported by the stage, wherein the lift-off light irradiation unit
includes first laser light scanning for scanning the interface in a
first direction parallel to the interface with the laser light in
the form of a line beam which is transverse to the first direction,
and second laser light scanning for scanning the interface in a
second direction which is parallel to the interface and different
from the first direction with the laser light in the form of a line
beam which is transverse to the second direction, and in each of
the first and second laser light scanning, an irradiation intensity
of the laser light is modulated such that an irradiation intensity
of the laser light for at least part of an interface between the
intermediate region of the synthetic resin film and the glass base
is lower than an irradiation intensity of the laser light for the
interface between the plurality of flexible substrate regions of
the synthetic resin film and the glass base.
[0021] In one embodiment, in each of the first and second laser
light scanning, an irradiation intensity of the laser light is
lower than a threshold level which is necessary for delaminating
the plurality of flexible substrate regions of the synthetic resin
film from the glass base through a single scanning cycle, and a sum
of irradiation intensities of the laser light in the first and
second laser light scanning is higher than the threshold level.
[0022] In one embodiment, the apparatus further includes an
actuator for increasing a distance from the stage to the glass base
while the stage is kept in contact with the second surface of the
multilayer stack, thereby separating the multilayer stack into a
first portion and a second portion, wherein the first portion of
the multilayer stack includes a plurality of OLED devices which are
in contact with the stage, and the plurality of OLED devices
respectively include the plurality of functional layer regions and
include the plurality of flexible substrate regions of the
synthetic resin film, and the second portion of the multilayer
stack includes the glass base and the intermediate region of the
synthetic resin film.
Advantageous Effects of Invention
[0023] According to an embodiment of the present invention, a novel
method for producing a flexible OLED device which is capable of
solving the above-described problems is provided.
BRIEF DESCRIPTION OF DRAWINGS
[0024] FIG. 1A is a plan view showing a configuration example of a
multilayer stack used in a flexible OLED device production method
of the present disclosure.
[0025] FIG. 1B is a cross-sectional view of the multilayer stack
taken along line B-B of FIG. 1A.
[0026] FIG. 1C is a cross-sectional view showing another example of
the multilayer stack.
[0027] FIG. 1D is a cross-sectional view showing still another
example of the multilayer stack.
[0028] FIG. 2 is a cross-sectional view schematically showing the
dividing positions in the multilayer stack.
[0029] FIG. 3A is a diagram schematically showing a state
immediately before a stage supports a multilayer stack.
[0030] FIG. 3B is a diagram schematically showing a state where the
stage supports the multilayer stack.
[0031] FIG. 3C is a diagram schematically showing that the
interface between a glass base and a plastic film of the multilayer
stack with laser light (lift-off light).
[0032] FIG. 4A is a perspective view schematically showing
irradiation of the multilayer stack with a line beam emitted from a
line beam source of an LLO unit.
[0033] FIG. 4B is a perspective view schematically showing the
position of the stage at the start of the first laser light
scanning.
[0034] FIG. 4C is a perspective view schematically showing the
position of the stage at the end of the first laser light
scanning.
[0035] FIG. 4D is a perspective view schematically showing a
multilayer stack with its orientation being rotated by 90.degree.
on an axis parallel to the Z-axis.
[0036] FIG. 4E is a perspective view schematically showing the
position of the stage at the end of the second laser light
scanning.
[0037] FIG. 5A is a perspective view schematically showing the
first laser light scanning.
[0038] FIG. 5B is a perspective view schematically showing the
first laser light scanning.
[0039] FIG. 5C is a perspective view schematically showing the
first laser light scanning.
[0040] FIG. 5D is a perspective view schematically showing the
second laser light scanning.
[0041] FIG. 6 is a diagram schematically showing an example of the
distribution in the Y-axis direction of the irradiation intensity
of the lift-off light in the first laser light scanning.
[0042] FIG. 7 is a diagram schematically showing another example of
the distribution in the Y-axis direction of the irradiation
intensity of the lift-off light in the first laser light
scanning.
[0043] FIG. 8 is a diagram schematically showing an example of the
distribution in the X-axis direction (scanning direction) of the
irradiation intensity of the lift-off light in the first laser
light scanning.
[0044] FIG. 9 is a diagram schematically showing another example of
the distribution in the X-axis direction of the irradiation
intensity of the lift-off light in the first laser light
scanning.
[0045] FIG. 10A is a diagram schematically showing still another
example of the distribution in the X-axis direction of the
irradiation intensity of the lift-off light.
[0046] FIG. 10B is a diagram schematically showing still another
example of the distribution in the X-axis direction of the
irradiation intensity of the lift-off light.
[0047] FIG. 11 is a diagram schematically showing an example of the
distribution in the Y-axis direction of the irradiation intensity
of the lift-off light in the second laser light scanning.
[0048] FIG. 12 is a diagram schematically showing another example
of the distribution in the Y-axis direction of the irradiation
intensity of the lift-off light in the second laser light
scanning.
[0049] FIG. 13 is a diagram schematically showing an example of the
distribution in the X-axis direction (scanning direction) of the
irradiation intensity of the lift-off light in the second laser
light scanning.
[0050] FIG. 14 is a diagram schematically showing another example
of the distribution in the X-axis direction of the irradiation
intensity of the lift-off light in the second laser light
scanning.
[0051] FIG. 15A is a plan view schematically showing low
irradiation regions by the first laser light scanning.
[0052] FIG. 15B is a plan view schematically showing low
irradiation regions by the second laser light scanning.
[0053] FIG. 15C is a plan view schematically showing the entire
shape of a low irradiation region after the first and second laser
light scanning.
[0054] FIG. 16A is a cross-sectional view schematically showing the
multilayer stack before the multilayer stack is separated into the
first portion and the second portion after irradiation with
lift-off light.
[0055] FIG. 16B is a cross-sectional view schematically showing the
multilayer stack separated into the first portion and the second
portion.
[0056] FIG. 17 is a perspective view showing the glass base
separated from the multilayer stack by an LLO unit.
[0057] FIG. 18 is a perspective view showing removal of the glass
base from the stage.
[0058] FIG. 19 is a perspective view showing the stage from which
the glass base has been removed.
[0059] FIG. 20 is a cross-sectional view showing the stage from
which the glass base has been removed.
[0060] FIG. 21 is a cross-sectional view showing flexible OLED
devices detached from the stage.
[0061] FIG. 22 is a cross-sectional view showing another protection
sheet bound to a plurality of OLED devices which are in contact
with the stage.
[0062] FIG. 23 is a cross-sectional view showing a carrier sheet
carrying a plurality of parts which are to be mounted to the
plurality of OLED devices.
[0063] FIG. 24A is a cross-sectional view illustrating a step of
the flexible OLED device production method in an embodiment of the
present disclosure.
[0064] FIG. 24B is a cross-sectional view illustrating a step of
the flexible OLED device production method in an embodiment of the
present disclosure.
[0065] FIG. 24C is a cross-sectional view illustrating a step of
the flexible OLED device production method in an embodiment of the
present disclosure.
[0066] FIG. 24D is a cross-sectional view illustrating a step of
the flexible OLED device production method in an embodiment of the
present disclosure.
[0067] FIG. 25 is an equivalent circuit diagram of a single
sub-pixel in a flexible OLED device.
[0068] FIG. 26 is a perspective view of the multilayer stack in the
middle of the production process.
DESCRIPTION OF EMBODIMENTS
[0069] An embodiment of a method and apparatus for producing a
flexible OLED device of the present disclosure is described with
reference to the drawings. In the following description,
unnecessarily detailed description will be omitted. For example,
detailed description of well-known matter and repetitive
description of substantially identical elements will be omitted.
This is for the purpose of avoiding the following description from
being unnecessarily redundant and assisting those skilled in the
art to easily understand the description. The present inventors
provide the attached drawings and the following description for the
purpose of assisting those skilled in the art to fully understand
the present disclosure. Providing these drawings and description
does not intend to limit the subject matter recited in the
claims.
[0070] <Multilayer Stack>
[0071] See FIG. 1A and FIG. 1B. In a flexible OLED device
production method of the present embodiment, firstly, a multilayer
stack 100 illustrated in FIG. 1A and FIG. 1B is provided. FIG. 1A
is a plan view of the multilayer stack 100. FIG. 1B is a
cross-sectional view of the multilayer stack 100 taken along line
B-B of FIG. 1A. In FIG. 1A and FIG. 1B, an XYZ coordinate system
with X-axis, Y-axis and Z-axis, which are perpendicular to one
another, is shown for reference.
[0072] The multilayer stack 100 includes a glass base (motherboard
or carrier) 10, a plurality of functional layer regions 20 each
including a TFT layer 20A and an OLED layer 20B, a synthetic resin
film (hereinafter, simply referred to as "plastic film") 30
provided between the glass base 10 and the plurality of functional
layer regions 20 and bound to the glass base 10, and a protection
sheet 50 covering the plurality of functional layer regions 20. The
multilayer stack 100 further includes a gas barrier film 40
provided between the plurality of functional layer regions 20 and
the protection sheet 50 so as to cover the entirety of the
functional layer regions 20. The multilayer stack 100 may include
another unshown layer, such as a buffer layer.
[0073] The first surface 100a of the multilayer stack 100 is
defined by the glass base 10. The second surface 100b of the
multilayer stack 100 is defined by the protection sheet 50. The
glass base 10 and the protection sheet 50 are materials temporarily
used in the production process but are not constituents of a final
flexible OLED device.
[0074] The plastic film 30 shown in the drawings includes a
plurality of flexible substrate regions 30d respectively supporting
the plurality of functional layer regions 20, and an intermediate
region 30i surrounding each of the flexible substrate regions 30d.
The flexible substrate regions 30d and the intermediate region 30i
are merely different portions of a single continuous plastic film
30 and do not need to be physically distinguished. In other words,
regions of the plastic film 30 lying immediately under respective
ones of the functional layer regions 20 are the flexible substrate
regions 30d, and the other region of the plastic film 30 is the
intermediate region 30i.
[0075] Each of the plurality of functional layer regions is a
constituent of a final flexible OLED device. In other words, the
multilayer stack 100 has such a structure that a plurality of
flexible OLED devices which are not yet divided from one another
are supported by a single glass base 10. Each of the functional
layer regions 20 has such a shape that, for example, the thickness
(size in Z-axis direction) is several tens of micrometers, the
length (size in X-axis direction) is about 12 cm, and the width
(size in Y-axis direction) is about 7 cm. These sizes can be set to
arbitrary values according to the required largeness of the display
screen. The shape in the XY plane of each of the functional layer
regions 20 is rectangular in the example illustrated in the
drawings but is not limited to this example. The shape in the XY
plane of each of the functional layer regions 20 may include a
square, a polygon, or a shape which includes a curve in the
contour.
[0076] As shown in FIG. 1A, the flexible substrate regions 30d are
two-dimensionally arrayed in rows and columns according to the
arrangement of the flexible OLED devices. The intermediate region
30i consists of a plurality of stripes perpendicular to one another
and forms a grid pattern. The width of the stripes is, for example,
about 1-4 mm. The flexible substrate region 30d of the plastic film
30 functions as the "flexible substrate" in each flexible OLED
device which is in the form of a final product. Meanwhile, the
intermediate region 30i of the plastic film 30 is not a constituent
of the final product.
[0077] In an embodiment of the present disclosure, the
configuration of the multilayer stack 100 is not limited to the
example illustrated in the drawings. The number of functional layer
regions 20 supported by a single glass base 10 is arbitrary.
[0078] The size or proportion of each component illustrated in
respective drawings is determined from the viewpoint of
understandability. The actual size or proportion is not necessarily
reflected in the drawings.
[0079] The multilayer stack 100 which can be used in the production
method of the present disclosure is not limited to the example
illustrated in FIG. 1A and FIG. 1B. FIG. 1C and FIG. 1D are
cross-sectional views showing other examples of the multilayer
stack 100. In the example illustrated FIG. 1C, the protection sheet
50 covers the entirety of the plastic film 30 and extends outward
beyond the plastic film 30. In the example illustrated FIG. 1D, the
protection sheet 50 covers the entirety of the plastic film 30 and
extends outward beyond the glass base 10. As will be described
later, after the glass base 10 is separated from the multilayer
stack 100, the multilayer stack 100 is a thin flexible sheet-like
structure which has no rigidity. The protection sheet 50 serves to
protect the functional layer regions 20 from impact and abrasion
when the functional layer regions 20 collide with or come into
contact with external apparatuses or instruments in the step of
delaminating the glass base 10 and the steps after the
delaminating. Since the protection sheet 50 is peeled off from the
multilayer stack 100 in the end, a typical example of the
protection sheet 50 has a laminate structure which includes an
adhesive layer of a relatively small adhesive force (a layer of an
applied mold-releasing agent) over its surface. The more detailed
description of the multilayer stack 100 will be described
later.
[0080] <Dividing of OLED Devices>
[0081] According to the flexible OLED device production method of
the present embodiment, after the step of providing the
above-described multilayer stack 100, the step of dividing an
intermediate region 30i and respective ones of a plurality of
flexible substrate regions 30d of the plastic film 30 from one
another is carried out.
[0082] FIG. 2 is a cross-sectional view schematically showing the
positions for dividing the intermediate region 30i and respective
ones of the plurality of flexible substrate regions 30d of the
plastic film 30 from one another. The positions of irradiation
extend along the periphery of each of the flexible substrate
regions 30d. In FIG. 2, the positions indicated by arrows are
irradiated with a laser beam for cutting. Part of the multilayer
stack 100 exclusive of the glass base 10 is cut into a plurality of
OLED devices 1000 and the remaining unnecessary portions. By
cutting, a gap of several tens of micrometers to several hundreds
of micrometers is formed between each of the OLED devices 1000 and
a portion surrounding the OLED device 1000. The cutting can also be
realized by a dicing saw instead of the laser beam irradiation.
After the cutting, the OLED devices 1000 and the remaining
unnecessary portions are still bound to the glass base 10.
[0083] When the cutting is realized by a laser beam, the wavelength
of the laser beam may be in any of the infrared, visible and
ultraviolet bands. From the viewpoint of reducing the effect of the
cutting on the glass base 10, the laser beam desirably has a
wavelength in the range of green to ultraviolet. For example, when
a Nd:YAG laser device is used, the cutting can be carried out using
a second harmonic wave (wavelength: 532 nm) or a third harmonic
wave (wavelength: 343 nm or 355 nm). In such a case, the laser
power is adjusted to 1 to 3 watts, and the scanning rate is set to
about 500 mm per second, so that the multilayer structure supported
by the glass base 10 can be cut (divided) into OLED devices and
unnecessary portions without damaging the glass base 10.
[0084] According to the embodiment of the present disclosure, the
timing of the above-described cutting is earlier than in the prior
art. Since the cutting is carried out while the plastic film 30 is
bound to the glass base 10, alignment for the cutting can be made
with high precision and accuracy even if the gap between adjoining
OLED devices 1000 is narrow. Thus, the gap between adjoining OLED
devices 1000 can be shortened, and accordingly, useless portions
which are unnecessary for a final product can be reduced. In the
prior art, after the delaminating from the glass base 10, a
polarizer, a heat radiation sheet, and/or an electromagnetic shield
can be adhered to the plastic film 30 so as to cover the entirety
of the surface (delaminated surface) of the plastic film 30. In
such a case, the polarizer, the heat radiation sheet, and/or the
electromagnetic shield are also divided by cutting into portions
covering the OLED devices 1000 and the remaining unnecessary
portions. The unnecessary portions are disposed of as waste. On the
other hand, according to the production method of the present
disclosure, production of such waste can be suppressed as will be
described later.
[0085] <Lift-Off Light Irradiation>
[0086] After the intermediate region 30i and respective ones of the
plurality of flexible substrate regions 30d of the plastic film 30
are divided from one another, the step of irradiating the interface
between the flexible substrate regions 30d of the plastic film 30
and the glass base 10 with laser light is carried out using a
lift-off light irradiation unit.
[0087] FIG. 3A schematically shows a state immediately before the
stage 210 supports the multilayer stack 100. In the present
embodiment, the stage 210 is a chuck stage which has a large number
of pores in the surface for suction. The multilayer stack 100 is
arranged such that the second surface 100b of the multilayer stack
100 faces the surface 210S of the stage 210, and is supported by
the stage 210.
[0088] FIG. 3B schematically shows a state where the stage 210
supports the multilayer stack 100. The arrangement of the stage 210
and the multilayer stack 100 is not limited to the example
illustrated in the drawing. For example, the multilayer stack 100
may be placed upside down such that the stage 210 is present under
the multilayer stack 100.
[0089] In the example illustrated in FIG. 3B, the multilayer stack
100 is in contact with the surface 210S of the stage 210, and the
stage 210 holds the multilayer stack 100 by suction.
[0090] Then, as shown in FIG. 3C, the interface between the plastic
film 30 and the glass base 10 is irradiated with laser light
(lift-off light) 216. FIG. 3C schematically illustrates irradiation
of the interface between the glass base 10 and the plastic film 30
of the multilayer stack 100 with the lift-off light 216 in the
shape of a line extending in a direction vertical to the sheet of
the drawing. A part of the plastic film 30 at the interface between
the glass base 10 and the plastic film 30 absorbs the lift-off
light 216 and decomposes (disappears). By scanning the
above-described interface with the lift-off light 216, the degree
of binding of the plastic film 30 to the glass base 10 is reduced.
The wavelength of the lift-off light 216 is typically in the
ultraviolet band. The wavelength of the lift-off light 216 is
selected such that the lift-off light 216 is hardly absorbed by the
glass base 10 but is absorbed by the plastic film 30 as much as
possible. The light absorption by the glass base 10 is, for
example, about 10% in the wavelength range of 343-355 nm but can
increase to 30-60% at 308 nm.
[0091] Hereinafter, lift-off light irradiation according to the
present embodiment is described in detail.
[0092] In the present embodiment, the LLO unit includes a line beam
source for emitting the lift-off light 216. The line beam source
includes a laser device and an optical system for shaping laser
light emitted from the laser device into a line beam. In the
present disclosure, the lift-off light irradiation unit is referred
to as "laser lift-off (LLO) unit".
[0093] FIG. 4A is a perspective view schematically showing
irradiation of the multilayer stack 100 with a line beam (lift-off
light 216) emitted from a line beam source 214 of an LLO unit 220.
For the sake of understandability, the stage 210, the multilayer
stack 100 and the line beam source 214 are shown as being spaced
away from one another in the Z-axis direction of the drawing.
During irradiation with the lift-off light 216, the second surface
100b of the multilayer stack 100 is in contact with the stage
210.
[0094] The LLO unit 220 includes a controller 300 for controlling
the operation of the line beam source 214 and the stage 210. The
controller 300 changes the irradiation intensity of lift-off light
emitted from the line beam source 214 according to the position of
the stage 210. The controller 300 can be a general-purpose computer
which has a known configuration. The controller 300 includes, for
example, a microprocessor and a nonvolatile memory. In the
nonvolatile memory, a program is stored which includes instructions
to the microprocessor.
[0095] FIG. 4B schematically shows the position of the stage 210
during irradiation with the lift-off light 216 (at the start of the
first laser light scanning). Although not shown in FIG. 4B, the
multilayer stack 100 is supported by the stage 210.
[0096] Examples of the laser device that emits the lift-off light
216 include gas laser devices such as excimer laser, solid laser
devices such as YAG laser, semiconductor laser devices, and other
types of laser devices. A XeCl excimer laser device can generate
laser light at the wavelength of 308 nm. When yttrium orthovanadate
(YVO.sub.4) doped with neodymium (Nd) or YVO.sub.4 doped with
ytterbium (Yb) is used as a lasing medium, the wavelength of laser
light (fundamental wave) emitted from the lasing medium is about
1000 nm.
Therefore, the fundamental wave can be converted by a wavelength
converter to laser light at the wavelength of 340-360 nm (third
harmonic wave) before it is used.
[0097] In the embodiment of the present disclosure, as will be
described later, laser light scanning is carried out multiple times
in different directions (first direction and second direction)
relative to the multilayer stack 100. A sacrificial layer or
delamination layer (a thin layer of a metal or amorphous silicon)
may be provided at the interface between the plastic film 30 and
the glass base 10. From the viewpoint of suppressing generation of
ashes, using laser light at the wavelength of 308 nm from the
excimer laser device, rather than laser light at the wavelength of
340-360 nm, is more effective. Providing the sacrificial layer is
highly effective in suppressing generation of ashes.
[0098] The position of irradiation with the lift-off light 216
moves relative to the glass base 10 for scanning with the lift-off
light 216. In the LLO unit 220, the multilayer stack 100 may be
movable while the light source 214 from which the lift-off light is
to be emitted and an optical unit (not shown) are stationary.
Alternatively, the light source 214 may be movable while the
multilayer stack 100 is stationary. In the present embodiment,
irradiation with the lift-off light 216 is carried out during a
period where the stage 210 moves from the position shown in FIG. 4B
to the position shown in FIG. 4C. That is, scanning with the
lift-off light 216 is carried out by movement of the stage 210 in
the X-axis direction (first laser light scanning).
[0099] Then, as illustrated in FIG. 4D, the stage 210 rotates by
90.degree. on an axis parallel to the Z-axis. Thereafter, as shown
in FIG. 4E, the stage 210 is irradiated with the lift-off light 216
while moving in the negative direction of the X-axis (second laser
light scanning). In each of the first and second laser light
scanning, the irradiation intensity of laser light is modulated
such that the irradiation intensity of laser light for at least
part of the interface between the intermediate region 30i of the
plastic film 30 and the glass base 10 is lower than the irradiation
intensity of laser light for the interface between the plurality of
flexible substrate regions 30d of the plastic film 30 and the glass
base 10. In each of the first and second laser light scanning, the
irradiation intensity of laser light is lower than a threshold
level which is necessary for delamination at the interface between
the plurality of flexible substrate regions 30d of the plastic film
30 and the glass base 10 through a single scanning cycle. However,
the sum of the irradiation intensities of laser light in the first
and second laser light scanning is higher than the threshold level.
Hereinafter, details of these two laser light scanning cycles are
described.
[0100] First, see FIG. 5A to FIG. 5D. FIG. 5A to FIG. 5D are
perspective views schematically showing the scanning with the
lift-off light 216. In these drawings, the direction of the Z-axis
is opposite to the direction of the Z-axis of FIG. 4A to FIG.
4C.
[0101] In FIG. 5A, the rays of the lift-off light 216 are
represented by broken line arrows. In FIG. 5B to FIG. 5D, the rays
of the lift-off light 216 are represented by solid line arrows. The
broken line arrows represent rays whose irradiation intensity is
relatively low as compared with the solid line arrows. The state of
FIG. 5D corresponds to the state of FIG. 4D. The stage 210 of FIG.
5D results from rotation of the stage 210 of FIG. 5C by 90.degree.
on an axis parallel to the Z-axis. In the present embodiment,
scanning with the lift-off light 216 is first carried out along the
longer side of the multilayer stack 100 and then carried out along
the shorter side of the multilayer stack 100. Such an order is
arbitrary.
[0102] In the present embodiment, the lift-off light 216 is a line
beam extending in a direction parallel to the peripheral edge of
the glass base 10 (in this example, the Y-axis direction). This
line beam is emitted from the line beam source 214 shown in FIG. 4A
and other drawings. The irradiation position of the lift-off light
216 on the multilayer stack 100 can be moved not only in the
positive direction of the X-axis but also in the negative direction
of the X-axis with the passage of time as shown in FIG. 5A, FIG.
5B, FIG. 5C and FIG. 5D.
[0103] Next, see FIG. 6. FIG. 6 is a diagram schematically showing
an example of the distribution in the Y-axis direction of the
irradiation intensity of the lift-off light 216. In the graph of
FIG. 6, the horizontal axis represents the Y-axis coordinate of the
irradiation region, and the vertical axis represents the
irradiation intensity. The irradiation intensity is expressed by
the energy density per unit area (e.g., [mJ/cm.sup.2]). In the
graph of FIG. 6, specific values of the irradiation intensity are
not shown. The irradiation intensity refers to a value in the range
of, for example, not less than 0 mJ/cm.sup.2 and not more than 500
mJ/cm.sup.2. In the graph of FIG. 6, a solid line represents the
Y-axis direction distribution I(Y) of the irradiation intensity,
and a dot-chain line represents threshold level Th of the
irradiation intensity which is necessary for delamination. In the
present disclosure, the "threshold level" means a level at which
the plastic film 30 sufficiently delaminates from the glass base
10. Threshold level Th is, for example, 250-300 mJ/cm.sup.2. When a
sacrificial layer is provided between the plastic film 30 and the
glass base 10, threshold level Th can be increased to, for example,
300-600 mJ/cm.sup.2. Finally, in a region irradiated with lift-off
light at an irradiation intensity lower than this threshold level
Th, the amount of lift-off light absorbed by the plastic film 30 is
insufficient. Therefore, the plastic film 30 in that region remains
bound, without being delaminated from the glass base 10.
[0104] According to the present embodiment, the irradiation
intensity does not exceed threshold level Th at any position
through a single laser light scanning cycle.
[0105] In FIG. 6, a cross section of the multilayer stack 100 which
is parallel to the YZ plane is shown above the graph for reference.
The glass base 10 extends from position Y0 to position Y5. The OLED
device 1000 on the left-hand side resides in the region extending
from position Y1 to position Y2. The OLED device 1000 on the
right-hand side resides in the region extending from position Y3 to
position Y4. In other words, the flexible substrate regions 30d of
the plastic film 30 correspond to the region extending from
position Y1 to position Y2 and the region extending from position
Y3 to position Y4. Meanwhile, the intermediate region 30i of the
plastic film 30 corresponds to the region extending from position
Y0 to position Y1, the region extending from position Y2 to
position Y3, and the region extending from position Y4 to position
Y5.
[0106] In the example of FIG. 6, the irradiation intensity
distribution I(Y) of the lift-off light is, for example, in a range
of 50% to 98% of threshold level Th in a region larger than the
region extending from position Y0 to position Y5. In the present
embodiment, the lift-off light is a line beam which is longer than
the size in the Y-axis direction of the glass base 10. The
irradiation intensity of the line beam achieved through a single
scanning cycle is insufficient for delamination. The smallest value
of the irradiation intensity distribution I(Y) of the lift-off
light during the scanning is, for example, 0 mJ/cm.sup.2 but may be
greater than 0 mJ/cm.sup.2 (e.g., 20-130 mJ/cm.sup.2). It is only
required that the sum of the irradiation intensities achieved
through two lift-off light irradiation cycles does not reach a
level which is necessary for delaminating the intermediate region
30i of the plastic film 30 from the glass base 10.
[0107] In the example of FIG. 6, the irradiation intensity
distribution I(Y) of the lift-off light is linear although the
embodiment of the present disclosure is not limited to such an
example. For example, as in the example illustrated in FIG. 7, a
part or the entirety of the irradiation intensity distribution I(Y)
of the lift-off light may be curved. When an amorphous
semiconductor is heated and crystallized by irradiation with laser
light in the shape of a line beam, the irradiation intensity
distribution is desired to be uniform in order to achieve uniform
crystallinity. On the other hand, when the delamination in the
present embodiment is carried out, the line beam does not need to
be uniform so long as the irradiation intensity of the lift-off
light at the interface which needs delamination exceeds threshold
level Th after two scanning cycles.
[0108] Next, see FIG. 8. FIG. 8 is a diagram schematically showing
an example of the distribution in the X-axis direction (scanning
direction) of the irradiation intensity of the lift-off light 216.
In the graph of FIG. 8, the horizontal axis represents the X-axis
coordinate of the irradiation position, and the vertical axis
represents the irradiation intensity. In the graph of FIG. 8, a
solid line represents the X-axis direction distribution I(X) of the
irradiation intensity, and a dot-chain line represents threshold
level Th of the irradiation intensity which is necessary for
delamination.
[0109] In FIG. 8, a cross section of the multilayer stack 100 which
is parallel to the XZ plane is shown above the graph for reference.
This cross section is perpendicular to the cross section of FIG. 6.
The glass base 10 extends from position X0 to position X5. The OLED
device 1000 on the left-hand side in the drawing resides in the
region extending from position X1 to position X2. The OLED device
1000 on the right-hand side resides in the region extending from
position X3 to position X4. In other words, the flexible substrate
regions 30d of the plastic film 30 correspond to the region
extending from position X1 to position X2 and the region extending
from position X3 to position X4. Meanwhile, the intermediate region
30i of the plastic film 30 corresponds to the region extending from
position X0 to position X1 (width: W1), the region extending from
position X2 to position X3 (width: W3), and the region extending
from position X4 to position X5 (width: W3). The intermediate
region 30i at the left edge of the plastic film 30 in FIG. 8
(width: W1) includes a region in which the irradiation intensity is
sufficiently lower than threshold level Th (width: S1). Meanwhile,
the intermediate region 30i at the right edge of the plastic film
30 in FIG. 8 (width: W2) includes another region in which the
irradiation intensity is sufficiently lower than threshold level Th
(width: S2). Here, W1>S1 and W2>S2 hold. It is preferred that
width S1 is not less than 50% of width W1 and width S2 is not less
than 50% of width W2.
[0110] The X-axis direction distribution I(X) of the irradiation
intensity represents the whole (total or integral value) of a
single scanning cycle with the lift-off light. For example, while
the irradiation position of the lift-off light (the position of the
center line of the line beam) moves from position X0 to position
X1, the region extending from position X1 to position X5 is not
irradiated with the lift-off light. In this period, the irradiation
intensity of the lift-off light in the region extending from
position X1 to position X5 is, as a matter of course, zero.
[0111] The line width (the short axis dimension, the size in the
X-axis direction) of the lift-off light 216 can be, for example,
about 0.2 mm (=200 .mu.m). This dimension defines the largeness of
the irradiation region at the interface between the plastic film 30
and the glass base 10 at a certain time. The lift-off light 216 can
be emitted in the form of a pulsed or continuous wave. Irradiation
with the pulsed wave can be carried out at the frequency (the
number of shots in one second) of, for example, about 200 times per
second. When the lift-off light 216 is a pulsed wave, the scanning
speed is determined such that two consecutive shots form
partially-overlapping irradiation regions. If, for example, the
line width (the short axis dimension, the size in the X-axis
direction) of the lift-off light 216 is 0.2 mm and the irradiation
position moves at 20 mm per second in the X-axis direction, a gap
can occur between neighboring shots so long as the number of shots
per second is less than 100. Therefore, the number of shots per
second needs to exceed 100.
[0112] The positioning accuracy of the irradiation position depends
on the mechanical forwarding accuracy of the stage 210. When a YAG
laser device is used, the line width (the short axis dimension, the
size in the X-axis direction) of the lift-off light 216 can be set
to, for example, 40 .mu.m. When the stage 210 is moved stepwise at
intervals of 20 .mu.m, the overlap of irradiation regions formed by
two consecutive shots can be 50%. When the stage 210 is moved
stepwise at intervals of 30 .mu.m, the overlap of irradiation
regions formed by two consecutive shots can be 75%. Although, in
general, the line width (the short axis dimension, the size in the
X-axis direction) of the lift-off light 216 depends on the type of
the laser light source and the optical system, the irradiation
intensity can be changed without modulating the power of the laser
light source by controlling the overlap of irradiation regions.
[0113] When the irradiation position of the lift-off light is
forwarded stepwise, "stepwise movement of the line beam source 214"
and "pulsed irradiation with the lift-off light" can be repeated.
In this case, irradiation with the lift-off light can be carried
out while movement of the line beam source 214 relative to the
stage 210 is stopped. In irradiation of a stationary object with
laser light, adjustment of the irradiation intensity to a target
value is easier than in irradiation of a moving object with laser
light. For example, the irradiation intensity can be adjusted by
increasing or decreasing the number of irradiation pulses or the
irradiation duration at a stationary position.
[0114] When the moving speed (scanning speed) of the irradiation
position is fixed to a predetermined value, the irradiation
intensity can be modulated by increasing or decreasing the number
of shots per second. On the contrary, when the number of shots per
second is fixed, the irradiation intensity can be modulated by
increasing or decreasing the moving speed (scanning speed) of the
irradiation position. The irradiation intensity can be modulated by
changing the other parameters, e.g., the power of the line beam
source 214 or the optical distance from the line beam source 214 to
the multilayer stack 100. Also, a low irradiation region can be
formed by providing a mechanical shutter between the line beam
source 214 and the glass base 10 such that this shutter blocks the
optical path of the lift-off light.
[0115] As seen from FIG. 8, in this example, the irradiation
intensity of lift-off light for at least part of the interface
between the intermediate region 30i of the plastic film 30 and the
glass base 10 is lower than the irradiation intensity of lift-off
light for the interface between the flexible substrate regions 30d
of the plastic film 30 and the glass base 10. The region of this
"at least part" may be referred to as "low irradiation region". In
the example of FIG. 8, the low irradiation region includes two
parallel stripe regions extending along the peripheral edge of the
glass base 10 (a region of width S1 and a region of width S2). The
two stripe regions can be formed by irradiation with weak lift-off
light 216 shown in FIG. 5A.
[0116] FIG. 9 shows an example where the irradiation intensity is
temporarily lower than threshold level Th in the middle of the
scanning with the lift-off light 216. Specifically, the irradiation
intensity is lower than threshold level Th in part of the region
extending from position X2 to position X3 (width: S3). In this
example, the "low irradiation region" at the interface between the
intermediate region 30i of the plastic film 30 and the glass base
10 includes not only the two stripe regions but also a single
middle stripe region (width: S3) which is parallel to the two
stripe regions. Each of widths S1, S2, S3 of these stripe regions
is, for example, not less than 1 mm and, in a certain example, not
less than 3 mm.
[0117] In the examples of FIG. 8 and FIG. 9, two OLED devices 1000
are arranged in the direction of the X-axis. When N is an integer
not less than 3 and N OLED devices 1000 are arranged in the
direction of the X-axis, the total number of stripes formed by the
intermediate region 30i lying between two adjoining OLED devices
1000 is N-1. It is not necessary to provide a low irradiation
region in all of the N-1 stripes. Alternatively, a plurality of low
irradiation regions may be provided for an intermediate region 30i
which forms a single stripe.
[0118] In the examples of FIG. 8 and FIG. 9, the low irradiation
region of width S1 and the low irradiation region of width S2 each
reach the peripheral edge of the plastic film 30, although the
embodiment of the present disclosure is not limited to this
example. For example, the low irradiation region can be in various
forms as shown in FIG. 10A and FIG. 10B. FIG. 10A and FIG. 10B are
diagrams schematically showing still other examples of the
distribution in the X-axis direction of the irradiation intensity
of the lift-off light. In these drawings, examples of the
modulation pattern of the irradiation intensity at the interface
between the intermediate region 30i surrounding the OLED device
1000 on the left-hand side of FIG. 8 and the glass base 10 are
shown.
[0119] In the example shown in FIG. 10A, the striped low
irradiation regions (width: S1) extending along the peripheral edge
of the plastic film 30 do not reach the peripheral edge of the
plastic film 30. The irradiation intensity of the lift-off light
may exceed threshold level Th before the glass base 10 is
irradiated with the lift-off light. As in the region extending from
position X1 to position X3 shown in FIG. 10A, the irradiation
intensity may gradually change. When the irradiation intensity
gradually changes, the width (the size in the scanning direction)
of the "low irradiation region" can be defined as the width of a
region in which the irradiation intensity in a single laser light
scanning cycle is lower than threshold level Th.
[0120] In the example shown in FIG. 10B, the low irradiation region
consists of a plurality of stripes which have a relatively narrow
width. When the lift-off light is, for example, pulsed light, such
a low irradiation region can be realized by applying consecutive
shots such that irradiation regions do not overlap each other.
[0121] Next, the second laser light scanning is described with
reference to FIG. 11 to FIG. 14. The second laser light scanning is
carried out in a direction different from the direction of the
first laser light scanning.
[0122] FIG. 11 and FIG. 12 correspond to FIG. 6 and FIG. 7. A
difference in the drawings resides in the difference in the cross
section of the multilayer stack 100. To meet the cross section of
the multilayer stack 100, position Y1 to position Y5 of FIG. 6 and
FIG. 7 are shifted to position Y1' to position Y5',
respectively.
[0123] FIG. 13 and FIG. 14 correspond to FIG. 8 and FIG. 9 and show
the irradiation intensity in the second laser light scanning. The
first difference in the drawings resides in the difference in the
cross section of the multilayer stack 100. To meet the cross
section of the multilayer stack 100, position X1 to position X5 of
FIG. 8 and FIG. 9 are shifted to position X1' to position X5',
respectively. Widths W1, W2, W3 are represented by widths W1', W2',
W3'. The waveform of the X-axis direction distribution I(X) of the
irradiation intensity of the lift-off light in the second laser
light scanning does not need to be identical with the X-axis
direction distribution I(X) of the irradiation intensity of the
lift-off light in the second laser light scanning. The highest
value and/or the lowest value of the irradiation intensity also do
not need to be identical between the first and second laser light
scanning.
[0124] FIG. 15A is a plan view showing the outline of the first
laser light scanning and an example of the shape and arrangement of
low irradiation regions S1, S2, S3 to be formed. The low
irradiation regions S1, S2, S3 are formed at positions not
overlapping the functional layer regions 20. Also in the other
regions than the low irradiation regions S1, S2, S3, the
irradiation intensity of the lift-off light in the first laser
light scanning does not reach threshold level Th.
[0125] FIG. 15B is a plan view showing the outline of the second
laser light scanning and an example of the shape and arrangement of
low irradiation regions S1', S2', S3' to be formed. The low
irradiation regions S1', S2', S3' are also formed at positions not
overlapping the functional layer regions 20. In the other regions
than the low irradiation regions S1', S2', S3', the irradiation
intensity of the lift-off light in the second laser light scanning
does not reach threshold level Th, but the accumulated value of the
irradiation intensity of the lift-off light in the first and second
laser light scanning exceeds threshold level Th.
[0126] FIG. 15C is a plan view showing an example of the entire
shape of a low irradiation region S after the two laser light
scanning cycles. In the example illustrated in FIG. 15C, the four
rectangular regions represent regions in which the total
irradiation intensity of the lift-off light sufficiently exceeds
threshold level Th through the two laser light scanning cycles. In
the hatched region S, the total irradiation intensity of the
lift-off light is lower than threshold level Th even through the
two laser light scanning cycles. In a region which is a low
irradiation region at least once in the two laser light scanning
cycles, the irradiation intensity of the lift-off light is
determined such that the irradiation intensity does not finally
reach threshold level Th.
[0127] According to the present embodiment, laser light scanning
which is carried out while modulating the irradiation intensity is
performed twice in different directions (directions transverse to
each other, typically directions perpendicular to each other),
whereby a low irradiation region S of a shape such as shown in FIG.
15C can be formed. Therefore, the intermediate region 30i of the
plastic film 30 can be selectively kept bound to the glass base
10.
[0128] In the present embodiment, the moving direction of the stage
210 in the second laser light scanning is opposite to the moving
direction of the stage 210 in the first laser light scanning,
although these moving directions may be identical.
[0129] <Lift-Off>
[0130] FIG. 16A illustrates a state where the multilayer stack 100
is in contact with the stage 210 after irradiation with the
lift-off light. While this state is maintained, the distance from
the stage 210 to the glass base 10 is increased. At this point in
time, the stage 210 of the present embodiment holds an OLED device
portion of the multilayer stack 100.
[0131] An unshown actuator holds the glass base 10 and moves the
entirety of the glass base 10 in the direction of arrow L, thereby
carrying out delaminating (lift-off). The glass base 10 can be
moved together with an unshown chuck stage while being adhered by
suction to the chuck stage. The direction of movement of the glass
base 10 does not need to be vertical, but may be diagonal, to the
first surface 100a of the multilayer stack 100. The movement of the
glass base does not need to be linear but may be rotational.
Alternatively, the stage 210 may be moved upward in the drawing
while the glass base 10 is secured by an unshown holder or another
stage.
[0132] FIG. 16B is a cross-sectional view showing the
thus-separated first portion 110 and second portion 120 of the
multilayer stack 100. FIG. 17 is a perspective view showing the
second portion 120 of the multilayer stack 100. The first portion
110 of the multilayer stack 100 includes a plurality of OLED
devices 1000 which are in contact with the stage 210. The
respective OLED devices 1000 include the functional layer regions
20 and the plurality of flexible substrate regions 30d of the
plastic film 30. Meanwhile, the second portion 120 of the
multilayer stack 100 includes the glass base 10 and the
intermediate region 30i of the plastic film 30. The intermediate
region 30i of the plastic film 30 is bound to the glass base 10 in
at least some low-irradiation regions. Thus, the entirety of the
intermediate region 30i of the plastic film 30 separates from the
stage 210 while the entirety of the intermediate region 30i is kept
adhered to the glass base 10.
[0133] In the example of FIG. 17, both the irradiation process with
the lift-off light and the delaminating process are carried out
using the LLO unit 220 that includes the stage 210. The embodiment
of the present disclosure is not limited to this example. The
irradiation process with the lift-off light may be carried out
using a lift-off light irradiation unit (LLO unit) which includes
the stage 210, while the delaminating process is carried out using
a different apparatus that includes another stage which is
different from the stage 210. In this case, after irradiation with
the lift-off light, it is necessary to transfer the multilayer
stack 100 from the stage 210 to another unshown stage. When the
same stage is used for carrying out both the irradiation process
with the lift-off light and the delaminating process, the step of
transferring the multilayer stack between the stages can be
omitted.
[0134] As described above, in the present embodiment, the step of
separating the multilayer stack 100 into the first portion 110 and
the second portion 120 is carried out while the stage 210 holds the
second surface 100b of the multilayer stack 100 by suction. The
essence of this separation step resides in that an unnecessary part
of the multilayer stack 100 which is not a constituent of the OLED
device 1000 separates together with the glass base 10 from the
stage 210. In the present embodiment, the cutting step illustrated
in FIG. 2, i.e., the step of cutting a part of the multilayer stack
100 exclusive of the glass base 10 into the plurality of OLED
devices 1000 and the remaining unnecessary portions, is carried out
before irradiation with the lift-off light. Carrying out the
cutting step before the lift-off light irradiation step is
effective in realizing the separation illustrated in FIG. 16B and
FIG. 17. In order that an unnecessary portion which is not a
constituent of the OLED device 1000 remains on the glass base 10,
the irradiation intensity of the lift-off light is modulated such
that part of that unnecessary portion is kept bound to the glass
base 10.
[0135] <Steps after Delaminating>
[0136] FIG. 18 is a perspective view showing the first portion 110
(OLED devices 1000) of the multilayer stack 100 adhered by suction
to the stage 210 and the second portion 120 (the glass base 10 and
objects bound thereto) at a position distant from the stage 210.
Unnecessary portions of the multilayer stack 100 which are not
constituents of the OLED devices 1000 are bound to the glass base
10.
[0137] FIG. 19 is a perspective view showing the first portion 110
of the multilayer stack 100 adhered by suction to the stage 210.
The first portion 110 of the multilayer stack 100 supported by the
stage 210 includes a plurality of OLED devices 1000 arrayed in rows
and columns. In the example of FIG. 19, a part of the plastic film
30, specifically the surface (delaminated surface) 30s of the
flexible substrate regions 30d, is exposed.
[0138] FIG. 20 is a cross-sectional view showing that the stage 210
holds the OLED devices 1000 by suction. This cross section is
parallel to the ZX plane. The direction of the Z-axis of FIG. 20 is
opposite to the direction of the Z-axis of FIG. 18 and FIG. 19.
[0139] Various processes can be sequentially or concurrently
performed on the plurality of OLED devices 1000 which are in
contact with the stage 210.
[0140] The "processes" to be performed on the OLED devices 1000 can
include attaching a dielectric and/or electrically-conductive film
to each of the plurality of OLED devices 1000, cleaning or etching
each of the plurality of OLED devices 1000, and mounting an optical
part and/or an electronic part to each of the plurality of OLED
devices 1000. Specifically, a part such as, for example, a
polarizer, encapsulation film, touchscreen, heat radiation sheet,
electromagnetic shield, driver integrated circuit, or the like, can
be mounted to the flexible substrate region 30d of each of the OLED
devices 1000. The sheet-like part includes a functional film which
can add an optical, electrical or magnetic function to the OLED
devices 1000.
[0141] The plurality of OLED devices 1000 are supported by the
stage 210 such that the OLED devices 1000 are adhered by suction to
the stage 210. The various processes which are to be performed on
each of the OLED devices 1000 can be efficiently carried out.
[0142] The surface 30s of the plastic film 30 delaminated from the
glass base 10 is active. Therefore, the surface 30s may be covered
with a protection film or subjected to a surface treatment for
conversion to a hydrophobic surface before various parts are
mounted to the surface 30s.
[0143] FIG. 21 is a cross-sectional view schematically showing the
OLED devices 1000 detached from the stage 210 after the sheet-like
part (functional film) 60 is mounted to the OLED devices 1000.
[0144] According to the prior art, the plastic film is delaminated
from the glass base before the OLED devices 1000 are divided from
one another. Therefore, when a subsequent process is carried out, a
large number of OLED devices 1000 are bound to a single plastic
film. Thus, it is difficult to carry out an efficient process on
each of the OLED devices 1000. When the OLED devices 1000 are
divided from one another after the sheet-like part is attached, a
portion of the sheet-like part which is present in an intermediate
region between adjoining two of the OLED devices 1000 is
useless.
[0145] On the other hand, according to the embodiment of the
present disclosure, a large number of OLED devices 1000 are still
orderly arrayed on the stage 210 after being delaminated from the
glass base 10. Therefore, various processes can be efficiently
performed on the OLED devices 1000 sequentially or
concurrently.
[0146] After the step of separating the multilayer stack 100 into
the first portion 110 and the second portion 120, the step of
adhering another protection sheet (second protection sheet) 70 to
the plurality of OLED devices 1000 which are in contact with the
stage 210 may be further performed as shown in FIG. 22. The second
protection sheet can perform the function of temporarily protecting
the surface of the flexible substrate regions 30d of the plastic
film 30 delaminated from the glass base 10. The second protection
sheet 70 can have the same laminate structure as that of the
previously-described protection sheet 50. The protection sheet 50
can be referred to as "first protection sheet 50".
[0147] The second protection sheet 70 may be adhered to the
plurality of OLED devices 1000 after various processes which have
previously been described are performed on the plurality of OLED
devices 1000 which are in contact with the stage 210.
[0148] When suction of the OLED devices 1000 by the stage 210 is
stopped after the second protection sheet 70 is adhered, the
plurality of OLED devices 1000 which are bound to the second
protection sheet 70 can be detached from the stage 210. Thereafter,
the second protection sheet 70 can function as a carrier for the
plurality of OLED devices 1000. This is transfer of the OLED
devices 1000 from the stage 210 to the second protection sheet 70.
Various processes may be sequentially or concurrently performed on
the plurality of OLED devices 1000 which are bound to the second
protection sheet 70.
[0149] FIG. 23 is a cross-sectional view showing a carrier sheet 90
carrying a plurality of parts (functional films) 80 which are to be
mounted to the plurality of OLED devices 1000. By moving this
carrier sheet 90 in the direction of arrow U, the respective parts
80 can be attached to the OLED devices 1000. The upper surface of
the parts 80 has an adhesive layer which is capable of strongly
adhering to the OLED devices 1000. Meanwhile, the adhesion between
the carrier sheet 90 and the parts 80 is relatively weak. Using
such a carrier sheet 90 enables a simultaneous "transfer" of the
parts 80. Such a transfer is readily realized because the plurality
of OLED devices 1000 are regularly arrayed on the stage 210 while
the OLED devices 1000 are supported by the stage 210.
[0150] Multilayer Stack
[0151] Hereinafter, the configuration of the multilayer stack 100
before the cutting of FIG. 2 is described in more detail.
[0152] First, see FIG. 24A. FIG. 24A is a cross-sectional view
showing the glass base 10 with the plastic film 30 provided on the
surface of the glass base 10. The glass base 10 is a supporting
substrate for processes. The thickness of the glass base 10 can be,
for example, about 0.3-0.7 mm.
[0153] In the present embodiment, the plastic film 30 is a
polyimide film having a thickness of, for example, not less than 5
.mu.m and not more than 100 .mu.m. The polyimide film can be formed
from a polyamide acid, which is a precursor of polyimide, or a
polyimide solution. The polyimide film may be formed by forming a
polyamide acid film on the surface of the glass base 10 and then
thermally imidizing the polyamide acid film. Alternatively, the
polyimide film may be formed by forming, on the surface of the
glass base 10, a film from a polyimide solution which is prepared
by melting a polyimide or dissolving a polyimide in an organic
solvent. The polyimide solution can be obtained by dissolving a
known polyimide in an arbitrary organic solvent. The polyimide
solution is applied to the surface 10s of the glass base 10 and
then dried, whereby a polyimide film can be formed.
[0154] In the case of a bottom emission type flexible display, it
is preferred that the polyimide film realizes high transmittance
over the entire range of visible light. The transparency of the
polyimide film can be represented by, for example, the total light
transmittance in accordance with JIS K7105-1981. The total light
transmittance can be set to not less than 80% or not less than 85%.
On the other hand, in the case of a top emission type flexible
display, it is not affected by the transmittance.
[0155] The plastic film 30 may be a film which is made of a
synthetic resin other than polyimide. Note that, however, in the
embodiment of the present disclosure, the process of forming a thin
film transistor includes a heat treatment at, for example, not less
than 350.degree. C., and therefore, the plastic film 30 is made of
a material which will not be deteriorated by this heat
treatment.
[0156] The plastic film 30 may be a multilayer structure including
a plurality of synthetic resin layers. In one form of the present
embodiment, in delaminating a flexible display structure from the
glass base 10, laser lift-off is carried out such that the plastic
film 30 is irradiated with ultraviolet laser light transmitted
through the glass base 10. A part of the plastic film 30 at the
interface with the glass base 10 needs to absorb the ultraviolet
laser light and decompose (disappear). Alternatively, for example,
a sacrificial layer which is to absorb laser light of a certain
wavelength band and produce a gas may be provided between the glass
base 10 and the plastic film 30. In this case, the plastic film 30
can be easily delaminated from the glass base 10 by irradiating the
sacrificial layer with the laser light. Providing the sacrificial
layer also achieves the effect of suppressing generation of
ashes.
[0157] <Polishing>
[0158] When there is an object (target) which is to be polished
away, such as particles or protuberances, on the surface 30x of the
plastic film 30, the target may be polished away using a polisher
such that the surface becomes flat. Detection of a foreign object,
such as particles, can be realized by, for example, processing of
an image obtained by an image sensor. After the polishing process,
a planarization process may be performed on the surface 30x of the
plastic film 30. The planarization process includes the step of
forming a film which improves the flatness (planarization film) on
the surface 30x of the plastic film 30. The planarization film does
not need to be made of a resin.
[0159] <Lower Gas Barrier Film>
[0160] Then, a gas barrier film may be formed on the plastic film
30. The gas barrier film can have various structures. Examples of
the gas barrier film include a silicon oxide film and a silicon
nitride film. Other examples of the gas barrier film can include a
multilayer film including an organic material layer and an
inorganic material layer. This gas barrier film may be referred to
as "lower gas barrier film" so as to be distinguishable from a gas
barrier film covering the functional layer regions 20, which will
be described later. The gas barrier film covering the functional
layer regions 20 can be referred to as "upper gas barrier
film".
[0161] <Functional Layer Region>
[0162] Hereinafter, the process of forming the functional layer
regions 20, including the TFT layer 20A and the OLED layer 20B, and
the upper gas barrier film 40 is described.
[0163] First, as shown in FIG. 24B, a plurality of functional layer
regions 20 are formed on a glass base 10. There is a plastic film
30 between the glass base 10 and the functional layer regions 20.
The plastic film 30 is bound to the glass base 10.
[0164] More specifically, the functional layer regions 20 include a
TFT layer 20A (lower layer) and an OLED layer 20B (upper layer).
The TFT layer 20A and the OLED layer 20B are sequentially formed by
a known method. The TFT layer 20A includes a circuit of a TFT array
which realizes an active matrix. The OLED layer 20B includes an
array of OLED elements, each of which can be driven independently.
The thickness of the TFT layer 20A is, for example, 4 .mu.m. The
thickness of the OLED layer 20B is, for example, 1 .mu.m.
[0165] FIG. 25 is a basic equivalent circuit diagram of a sub-pixel
in an organic EL (Electro Luminescence) display. A single pixel of
the display can consist of sub-pixels of different colors such as,
for example, R (red), G (green), and B (blue). The example
illustrated in FIG. 25 includes a selection TFT element Tr1, a
driving TFT element Tr2, a storage capacitor CH, and an OLED
element EL. The selection TFT element Tr1 is connected with a data
line DL and a selection line SL. The data line DL is a line for
transmitting data signals which define an image to be displayed.
The data line DL is electrically coupled with the gate of the
driving TFT element Tr2 via the selection TFT element Tr1. The
selection line SL is a line for transmitting signals for
controlling the ON/OFF state of the selection TFT element Tr1. The
driving TFT element Tr2 controls the state of the electrical
connection between a power line PL and the OLED element EL. When
the driving TFT element Tr2 is ON, an electric current flows from
the power line PL to a ground line GL via the OLED element EL. This
electric current allows the OLED element EL to emit light. Even
when the selection TFT element Tr1 is OFF, the storage capacitor CH
maintains the ON state of the driving TFT element Tr2.
[0166] The TFT layer 20A includes a selection TFT element Tr1, a
driving TFT element Tr2, a data line DL, and a selection line SL.
The OLED layer 20B includes an OLED element EL. Before formation of
the OLED layer 20B, the upper surface of the TFT layer 20A is
planarized by an interlayer insulating film that covers the TFT
array and various wires. A structure which supports the OLED layer
20B and which realizes active matrix driving of the OLED layer 20B
is referred to as "backplane".
[0167] The circuit elements and part of the lines shown in FIG. 25
can be included in any of the TFT layer 20A and the OLED layer 20B.
The lines shown in FIG. 25 are connected with an unshown driver
circuit.
[0168] In the embodiment of the present disclosure, the TFT layer
20A and the OLED layer 20B can have various specific
configurations. These configurations do not limit the present
disclosure. The TFT element included in the TFT layer 20A may have
a bottom gate type configuration or may have a top gate type
configuration. Emission by the OLED element included in the OLED
layer 20B may be of a bottom emission type or may be of a top
emission type. The specific configuration of the OLED element is
also arbitrary.
[0169] The material of a semiconductor layer which is a constituent
of the TFT element includes, for example, crystalline silicon,
amorphous silicon, and oxide semiconductor. In the embodiment of
the present disclosure, part of the process of forming the TFT
layer 20A includes a heat treatment step at 350.degree. C. or
higher for the purpose of improving the performance of the TFT
element.
[0170] <Upper Gas Barrier Film>
[0171] After formation of the above-described functional layer, the
entirety of the functional layer regions 20 is covered with a gas
barrier film (upper gas barrier film) 40 as shown in FIG. 24C. A
typical example of the upper gas barrier film 40 is a multilayer
film including an inorganic material layer and an organic material
layer. Elements such as an adhesive film, another functional layer
which is a constituent of a touchscreen, polarizers, etc., may be
provided between the upper gas barrier film 40 and the functional
layer regions 20 or in a layer overlying the upper gas barrier film
40. Formation of the upper gas barrier film 40 can be realized by a
Thin Film Encapsulation (TFE) technique. From the viewpoint of
encapsulation reliability, the WVTR (Water Vapor Transmission Rate)
of a thin film encapsulation structure is typically required to be
not more than 1.times.10.sup.-4 g/m.sup.2/day. According to the
embodiment of the present disclosure, this criterion is met. The
thickness of the upper gas barrier film 40 is, for example, not
more than 1.5 .mu.m.
[0172] FIG. 26 is a perspective view schematically showing the
upper surface side of the multilayer stack 100 at a point in time
when the upper gas barrier film 40 is formed. A single multilayer
stack 100 includes a plurality of OLED devices 1000 supported by
the glass base 10. In the example illustrated in FIG. 26, a single
multilayer stack 100 includes a larger number of functional layer
regions 20 than in the example illustrated in FIG. 1A. As
previously described, the number of functional layer regions 20
supported by a single glass base 10 is arbitrary.
[0173] <Protection Sheet>
[0174] Next, refer to FIG. 24D. As shown in FIG. 24D, a protection
sheet 50 is adhered to the upper surface of the multilayer stack
100. The protection sheet 50 can be made of a material such as, for
example, polyethylene terephthalate (PET), polyvinyl chloride
(PVC), or the like. As previously described, a typical example of
the protection sheet 50 has a laminate structure which includes a
layer of an applied mold-releasing agent at the surface. The
thickness of the protection sheet 50 can be, for example, not less
than 50 .mu.m and not more than 200 .mu.m.
[0175] After the thus-formed multilayer stack 100 is provided, the
production method of the present disclosure can be carried out
using the above-described production apparatus (LLO unit 220).
INDUSTRIAL APPLICABILITY
[0176] An embodiment of the present invention provides a novel
flexible OLED device production method. A flexible OLED device is
broadly applicable to smartphones, tablet computers, on-board
displays, and small-, medium- and large-sized television sets.
REFERENCE SIGNS LIST
[0177] 10 . . . glass base, 20 . . . functional layer region, 20A .
. . TFT layer, 20B . . . LED layer, 30 . . . plastic film, 30d . .
. flexible substrate region of plastic film, 30i . . . intermediate
region of plastic film, 40 . . . gas barrier film, 50 . . .
protection sheet, 100 . . . multilayer stack, 210 . . . stage, 220
. . . LLO unit, 1000 . . . OLED device
* * * * *