U.S. patent application number 15/041764 was filed with the patent office on 2016-06-09 for method for producing mold for minute pattern transfer, method for producing diffraction grating using the same, and method for producing organic el element including the diffraction grating.
This patent application is currently assigned to JX NIPPON OIL & ENERGY CORPORATION. The applicant listed for this patent is JX NIPPON OIL & ENERGY CORPORATION, TOKYO INSTITUTE OF TECHNOLOGY. Invention is credited to Maki FUKUDA, Satoshi MASUYAMA, Suzushi NISHIMURA, Takashi SEKI, Madoka TAKAHASHI.
Application Number | 20160161647 15/041764 |
Document ID | / |
Family ID | 46507259 |
Filed Date | 2016-06-09 |
United States Patent
Application |
20160161647 |
Kind Code |
A1 |
MASUYAMA; Satoshi ; et
al. |
June 9, 2016 |
METHOD FOR PRODUCING MOLD FOR MINUTE PATTERN TRANSFER, METHOD FOR
PRODUCING DIFFRACTION GRATING USING THE SAME, AND METHOD FOR
PRODUCING ORGANIC EL ELEMENT INCLUDING THE DIFFRACTION GRATING
Abstract
A method for producing a mold includes: applying a block
copolymer solution made of first and second polymers on a base
member; performing a first annealing process at a temperature
higher than Tg of the block copolymer after drying the coating
film; forming a concavity and convexity structure on the base
member by removing the second polymer by an etching process;
performing a second annealing process of the concavity and
convexity structure at a temperature higher than Tg of the first
polymer; forming a seed layer on the structure; laminating or
stacking a metal layer on the seed layer by an electroforming; and
peeling off the metal layer from the base member. The second
annealing process enables satisfactory transfer of a concavity and
convexity structure on the base member onto the metal layer.
Inventors: |
MASUYAMA; Satoshi;
(Yokohama-shi, JP) ; TAKAHASHI; Madoka; (Tokyo,
JP) ; NISHIMURA; Suzushi; (Yokohama-shi, JP) ;
FUKUDA; Maki; (Yokohama-shi, JP) ; SEKI; Takashi;
(Yokohama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JX NIPPON OIL & ENERGY CORPORATION
TOKYO INSTITUTE OF TECHNOLOGY |
Tokyo
Tokyo |
|
JP
JP |
|
|
Assignee: |
JX NIPPON OIL & ENERGY
CORPORATION
Tokyo
JP
TOKYO INSTITUTE OF TECHNOLOGY
Tokyo
JP
|
Family ID: |
46507259 |
Appl. No.: |
15/041764 |
Filed: |
February 11, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13938597 |
Jul 10, 2013 |
9291754 |
|
|
15041764 |
|
|
|
|
PCT/JP2012/050564 |
Jan 13, 2012 |
|
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13938597 |
|
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Current U.S.
Class: |
257/40 ; 205/70;
264/2.5; 359/574; 425/406 |
Current CPC
Class: |
H01L 51/52 20130101;
B29C 33/424 20130101; B29K 2105/0061 20130101; B29C 35/0805
20130101; B29C 43/36 20130101; G02B 27/4266 20130101; B29C 33/3857
20130101; B82Y 20/00 20130101; B81C 1/00031 20130101; B82Y 10/00
20130101; B29C 2035/0827 20130101; B82Y 40/00 20130101; G02B 5/1809
20130101; B29D 11/00769 20130101; G03F 7/0002 20130101; H01L 51/56
20130101; G02B 5/1852 20130101; B82Y 30/00 20130101; H01L 51/5275
20130101; B81C 2201/0149 20130101; G02B 5/1847 20130101; C25D 1/10
20130101; B29C 2043/023 20130101; B29C 43/021 20130101 |
International
Class: |
G02B 5/18 20060101
G02B005/18; B29C 43/36 20060101 B29C043/36; B29C 35/08 20060101
B29C035/08; H01L 51/56 20060101 H01L051/56; C25D 1/10 20060101
C25D001/10; G02B 27/42 20060101 G02B027/42; H01L 51/52 20060101
H01L051/52; B29C 43/02 20060101 B29C043/02; B29D 11/00 20060101
B29D011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 2011 |
JP |
2011-006487 |
Claims
1. A mold for minute pattern transfer produced by a producing
method, the producing method comprising a step of applying a block
copolymer solution made of at least a first polymer and a second
polymer on a surface of a base member; a step of drying a coating
film on the base member; a first heating step for heating the
coating film after the drying at a temperature higher than a glass
transition temperature of a block copolymer of the block copolymer
solution; an etching step for etching the coating film after the
first heating step to remove the second polymer so that a concavity
and convexity structure is formed on the base member; a second
heating step for heating the concavity and convexity structure at a
temperature higher than a glass transition temperature of the first
polymer; a step of forming a seed layer on the concavity and
convexity structure after the second heating step; a step of or
stacking a metal layer on the seed layer by an electroforming; and
a step of peeling off the base member having the concavity and
convexity structure from the metal layer and the seed layer.
2. A diffraction grating comprising a concavity and convexity
structure on a surface thereof, wherein the diffraction grating is
produced by a method comprising: pressing the mold obtained by the
method for producing the mold as defined in claim 1 to a
transparent substrate to which a curable resin has been applied;
curing the curable resin; and detaching the mold from the
transparent substrate to obtain a structure having a concavity and
convexity structure on the transparent substrate.
3. The diffraction grating of claim 2, wherein the diffraction
grating is produced by pressing the structure to a substrate to
which a sol-gel material has been applied; curing the sol-gel
material; and detaching the structure from the substrate to obtain
the diffraction grating having a concavity and convexity structure
made of the sol-gel material.
4. The diffraction grating according to claim 2, wherein a
cross-section shape of the concavity and convexity structure has a
chevron shape; and in a case that a Fourier-transformed image is
obtained by performing a two-dimensional fast Fourier-transform
processing on an concavity and convexity analysis image obtained by
an analyzing a planar shape of the concavity and convexity
structure with an atomic force microscope, the Fourier-transformed
image shows an annular pattern substantially centered at an origin
at which an absolute value of wavenumber is 0 .mu.m.sup.-1, and the
annular pattern is present within a region where the absolute value
of wavenumber is within a range of 10 .mu.m.sup.-1 or less.
5. The diffraction grating according to claim 3, wherein a
cross-section shape of the concavity and convexity structure has a
chevron shape; and in a case that a Fourier-transformed image is
obtained by performing a two-dimensional fast Fourier-transform
processing on an concavity and convexity analysis image obtained by
an analyzing a planar shape of the concavity and convexity
structure with an atomic force microscope, the Fourier-transformed
image shows an annular pattern substantially centered at an origin
at which an absolute value of wavenumber is 0 .mu.m.sup.-1, and the
annular pattern is present within a region where the absolute value
of wavenumber is within a range of 10 .mu.m.sup.-1 or less.
6. The diffraction grating according to claim 2, wherein a kurtosis
of the cross-section shape of the concavity and convexity structure
is -1.2 or more.
7. The diffraction grating according to claim 6, wherein the
kurtosis of the cross-section shape of the concavity and convexity
structure is -1.2 to 1.2.
8. The diffraction grating according to claim 2, wherein an average
pitch of a cross-section of the concavity and convexity structure
is 10 to 600 nm.
9. An organic EL element produced by stacking a transparent
electrode, an organic layer, a metal electrode in this order on the
concavity and convexity structure of the diffraction grating
produced by the method for producing the diffraction grating as
defined in claim 2.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. patent
application Ser. No. 13/938,597 filed on Jul. 10, 2013, which in
turn is a continuation application of International Patent
Application No. PCT/JP2012/050564 filed on Jan. 13, 2012 claiming
the benefit of priority of Japanese Patent Application No.
2011-6487 filed on Jan. 14, 2011. The disclosure of the prior
applications is hereby incorporated by reference herein in their
entireties.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method for producing a
mold for minute or fine pattern transfer used for nanoimprint and
the like, a method for producing a diffraction grating using the
same, and a method for producing an organic EL element an organic
EL element (Organic Electro-Luminescence element or organic light
emitting diode) including the diffraction grating as well as the
mold for the minute pattern transfer, the diffraction grating, and
the organic EL element, those of which are obtained by using the
methods described above.
[0004] 2. Description of the Related Art
[0005] There has been known a lithography method as a method for
forming a minute pattern such as a semiconductor integrated
circuit. The resolution of the pattern formed by the lithography
method is dependent on the wavelength of a light source and/or the
numerical aperture of an optical system, and a light source having
shorter wavelength is expected in order to meet demand for
miniaturized devices in recent years. However, the light source
having the short wavelength is expensive, development thereof is
not easy, and development of an optical material transmitting such
a short-wavelength light is also needed. Further, manufacture of a
large-area pattern by a conventional lithography method requires a
large-size optical element, thereby having difficulties in
technical and economic aspects. Thus, a novel method for forming a
desired pattern having a large area has been considered.
[0006] There has been known a nanoimprint method as the method for
forming the minute pattern without using a conventional lithography
apparatus. The nanoimprint method is a technique such that a
pattern of an order of nanometer can be transferred by sandwiching
resin between a mold and a substrate. The nanoimprint method
basically includes four steps of: i) application of a resin layer;
ii) press of the mold; iii) pattern transfer; and iv)
mold-releasing. The nanoimprint method is excellent in that
processing on a nanoscale can be realized by the simple process as
described above. Further, an apparatus used in the nanoimprint
method is simple or easy, is capable of performing a large-area
processing, and promises a high throughput. Thus, the nanoimprint
method is expected to come into practical use in many fields such
as a storage medium, an optical member, and a biochip, in addition
to a semiconductor device.
[0007] However, even in the nanoimprint method, a mold for
transferring a pattern having a line width of tens of nanometers
basically requires that the pattern of a resist (resist pattern) on
a silicon substrate is exposed and then is developed with using the
lithography apparatus. A current seed layer made of metal is formed
on the resist pattern to perform electroforming of the mold with
using the obtained resist pattern. However, in a case that
definition of the pattern is not more than 100 nm, coatability or
coverage of the current seed layer formed on the resist pattern by
a sputtering is decreased, and the film thickness of the current
seed layer obtained varies among the upper portion, the sidewall,
and the bottom portion (substrate exposed portion in a concave
portion of the pattern, that is a trench) of the resist pattern.
Especially, a problem arises such that formation of the current
seed layer preferentially proceeds at the upper portion of the
resist pattern to cause a narrowing of a trench opening. Thus, in a
case that a hole or trench and a ridge are formed on the substrate
by using a resist layer, there is a problem such that metal is less
likely to be deposited on the bottom portion of the hole or trench
during the formation of the current seed layer; and overhang is
caused at the upper portion of the ridge of the resist layer. In a
case that the electroforming process of a stacked body is performed
by using such a current seed layer, an electroformed layer is
joined to the upper part of the hole or trench due to the overhang
and a void is left inside the trench. As a result, the mold
obtained by the electroforming has a problem such that the mold has
low mechanical strength and therefore defects such as deformation
of the mold and pattern defect are caused.
[0008] In order to solve the problem(s) as described above,
Japanese Patent Application Laid-open No. 2010-017865 discloses a
method for manufacturing a mold for nanoimprint including the steps
of: forming a resist layer which includes a concavity and convexity
pattern on a substrate having a conductive surface and then
exposing the conductive surface at a concave portion of the
concavity and convexity pattern of the resist layer; performing
electroforming on the conductive surface exposed at the concave
portion of the concavity and convexity pattern of the resist layer
and then forming an electroformed layer having a film thickness
greater than that of the resist layer; and removing the substrate
having the conductive surface and the resist layer. According to
this method, it is possible to grow the electroformed layer in one
direction, that is, in an upward direction from the conductive
surface of the bottom portion of the resist pattern, without using
the current seed layer, and thus it is considered that no void
exists inside the mold for nanoimprint. However, even this method
has still been forced to depend on the lithography method to make
the mold used for the nanoimprint method.
[0009] The inventors of the present invention disclose, in
International Application No. PCT/JP2010/62110, a method for
obtaining a mold having a minute and irregular concavity and
convexity pattern formed therein by applying a block copolymer
solution including a block copolymer and a solvent, satisfying a
predetermined condition, onto a base member; and performing drying
to form a micro phase separation structure of the block copolymer.
According to this method, it is possible to obtain the mold used
for the nanoimprint and the like by using a self-organizing
phenomenon of the block copolymer without using the lithography
method. A mixture of a silicone-based polymer and a curing agent is
dripped onto the obtained mold and then cured to obtain the
transferred pattern. Then, a glass substrate to which a curable
resin has been applied is pressed against the transferred pattern
and the curable resin is cured by irradiation with ultraviolet
rays. In this way, a diffraction grating in which a transferred
pattern is duplicated is manufactured. It has been confirmed that
an organic EL element obtained by stacking a transparent electrode,
an organic layer, and a metal electrode on the diffraction grating
has sufficiently high light emission efficiency, sufficiently high
level of external extraction efficiency, sufficiently low
wavelength-dependence of light emission, sufficiently low
directivity of light emission, and sufficiently high power
efficiency.
[0010] It is desired to take the method for producing the
diffraction grating achieved in International Application No.
PCT/JP2010/62110 by the inventor(s) of the present invention one
step further, so as to improve the method to be suitable for mass
production of a product including the organic EL element and the
like.
[0011] In view of the above, an object of the present invention is
to provide a method for producing a mold for minute pattern
transfer, which is suitable for production of an optical component
such as a diffraction grating used for general products including
an organic EL element and the like, a method for producing a
diffraction grating using the obtained mold, and a method for
producing an organic EL element using such diffraction grating.
Another object of the present invention is to provide the mold for
the minute pattern transfer, the diffraction grating, and the
organic EL element, using the producing methods as described
above.
SUMMARY OF THE INVENTION
[0012] According to the present invention, there is provided a
method for producing a mold for minute or fine pattern transfer,
including: a step of applying a block copolymer solution made of at
least a first polymer (segment) and a second polymer (segment) on a
surface of a base member; a step of drying a coating film on the
base member; a first heating step for heating the coating film
after the drying at a temperature higher than a glass transition
temperature of a block copolymer of the block copolymer solution;
an etching step for etching the coating film after the first
heating step to remove the second polymer so that a concavity and
convexity structure is formed on the base member; a second heating
step for heating the concavity and convexity structure at a
temperature higher than a glass transition temperature of the first
polymer (segment); a step of forming a seed layer on the concavity
and convexity structure after the second heating step; a step of
laminating or stacking a metal layer on the seed layer by an
electroforming; and a step of peeling off the base member having
the concavity and convexity structure from the metal layer and the
seed layer.
[0013] In the method for producing the mold according to the
present invention, a micro phase separation structure of the block
copolymer may be generated during the drying step or the first
heating step, and the micro phase separation structure preferably
has a lamellar form.
[0014] In the method for producing the mold according to the
present invention, the concavity and convexity structure may be
heated, for 10 minutes to 100 hours, at a temperature ranging from
the glass transition temperature of the first polymer to a
temperature higher than the glass transition temperature of the
first polymer by 70 degrees Celsius during the second heating step.
Further, the concavity and convexity structure can be deformed to
have a chevron-shaped structure during the second heating step.
[0015] In the method for producing the mold according to the
present invention, a number average molecular weight (Mn) of the
block copolymer is preferably 500,000 or more and a molecular
weight distribution (Mw/Mn) of the block copolymer is preferably
1.5 or less. Further, a volume ratio between the first polymer and
the second polymer in the block copolymer is preferably 3:7 to 7:3
and a difference between solubility parameters of the first and
second polymers is preferably 0.1 to 10 (cal/cm.sup.3).sup.1/2 for
forming the micro phase separation structure.
[0016] In the method for producing the mold according to the
present invention, the first polymer forming the block copolymer is
preferably polystyrene and the second polymer forming the block
copolymer is preferably polymethyl methacrylate. In the block
copolymer solution, polyalkylene oxide may be contained as a
different homopolymer.
[0017] In the method for producing the mold according to the
present invention, the seed layer may be formed by one of a
non-electrolytic plating method, a sputtering method, and a vapor
deposition method. Further, the method for producing the mold
according to the present invention may include cleaning the mold
obtained by peeling off the base member having the concavity and
convexity structure from the metal layer and the seed layer; and
performing a mold-release treatment on a surface of the mold.
[0018] According to the second aspect of the present invention,
there are provided a method for producing a diffraction grating,
including: pressing the mold obtained by the method for producing
the mold to a transparent substrate to which a curable resin has
been applied; curing the curable resin; and detaching the mold from
the transparent substrate to obtain a structure having a concavity
and convexity structure on the transparent substrate.
[0019] In the method for producing a diffraction grating according
to the present invention, the structure may be the diffraction
grating.
[0020] Further, the method for producing a diffraction grating
according to the present invention may include: pressing the
structure to a substrate to which a sol-gel material has been
applied; curing the sol-gel material; and detaching the structure
from the substrate to obtain the diffraction grating having a
concavity and convexity structure made of the sol-gel material.
[0021] According to the third aspect of the present invention,
there is provided a method for producing an organic EL element,
wherein a transparent electrode, an organic layer, and a metal
electrode is stacked in this order on the concavity and convexity
structure of the diffraction grating produced by the method for
producing the diffraction grating, thereby producing the organic EL
element.
[0022] According to the fourth aspect of the present invention,
there is provided the mold for minute pattern transfer produced by
the producing method as defined in the first aspect.
[0023] According to the fifth aspect of the present invention,
there is provided the diffraction grating produced by the producing
method as defined in the second aspect. A cross-section shape of
the concavity and convexity structure of the surface of the
diffraction grating preferably has a chevron shape. Further, in a
case that a Fourier-transformed image is obtained by performing a
two-dimensional fast Fourier-transform processing on an concavity
and convexity analysis image obtained by an analyzing a planar
shape of the concavity and convexity structure with an atomic force
microscope, it is preferable that the Fourier-transformed image
shows an annular pattern substantially centered at an origin at
which an absolute value of wavenumber is 0 .mu.m.sup.-1 and that
the annular or circular pattern is present within a region where
the absolute value of wavenumber is 10 .mu.m.sup.-1, especially
within a range of from 1.25 to 5 .mu.m.sup.-1. A kurtosis of the
cross-section shape of the concavity and convexity structure of the
diffraction grating is preferably -1.2 or more, especially
preferably -1.2 to 1.2. An average pitch of the cross-section of
the concavity and convexity structure of the diffraction grating is
preferably 10 to 600 nm.
[0024] According to the sixth aspect of the present invention,
there is provided an organic EL element produced by the producing
method as defined in the third aspect.
[0025] According to a method for producing a mold of the present
invention, by performing a second heating process to a block
copolymer after an etching, a cross-section of a concavity and
convexity structure of the block copolymer has a smooth chevron
shape. Accordingly, the concavity and convexity structure of the
block copolymer can be completely covered with a seed layer having
a uniform film thickness and it is possible to manufacture an
electroformed mold having high mechanical strength without causing
a pattern defect or the like. With respect to surface texture of a
metal layer of the obtained mold, since concavities and convexities
are distributed substantially uniformly, residue of resin on the
side of the mold is suppressed when the block copolymer and a base
member are peeled off from the mold, and thus contamination of the
mold is reduced and peeling property of the mold is improved.
Accordingly, it is possible to obtain the mold having the high
mechanical strength without causing the pattern defect. Cleaning of
the mold is also performed easily. Even when the molecular weight
of the block copolymer is increased, it is possible to reliably
form the mold having a desired concavity and convexity pattern. By
performing the second heating step after the etching, it is
possible to remove impurities including, for example, a solvent
remained in the step before the second heating step such as the
etching. By using a method for producing a diffraction grating
according to the present invention, it is possible to produce, with
relative ease, the diffraction grating which diffracts light in a
visible region with low directivity and without
wavelength-dependence.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIGS. 1A-1H are schematic illustration showing each step of
a method for producing a mold of the present invention.
[0027] FIGS. 2A-2E are schematic illustration showing each step for
producing a diffraction grating using the mold obtained by the
method for producing the mold of the present invention.
[0028] FIG. 3 is a flowchart showing each step for the method for
producing the mold of the present invention.
[0029] FIG. 4 is a schematic illustration showing a stacked
structure of an organic EL element, in which the diffraction
grating obtained by the method for producing the diffraction
grating of the present invention is used.
[0030] FIG. 5A is a transmission electron micrograph of a
cross-section of a coating film after a first annealing process
obtained in Example 1.
[0031] FIG. 5B is a scanning electron micrograph of a cross-section
of a nickel mold from which a polymer component has been removed in
Example 1.
[0032] FIG. 5C is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by an
etching process in Example 1 by use of a scanning probe microscope
is displayed on a display.
[0033] FIG. 5D is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold, which has been formed by electroforming in Example 1, by use
of the scanning probe microscope is displayed on a display.
[0034] FIG. 5E is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
diffraction grating obtained in Example 1 by use of the scanning
probe microscope is displayed on a display.
[0035] FIG. 5F is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex
cross-section of the diffraction grating obtained in Example 1 by
use of the scanning probe microscope is displayed on a display.
[0036] FIG. 5G is a photograph showing a Fourier-transformed image,
in which a result of two-dimensional fast Fourier transform
processing conducted on a concavity and convexity analysis image,
which was obtained by use of an atomic force microscope, of the
surface of the diffraction grating obtained in Example 1, is
displayed on a display.
[0037] FIG. 6A is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by the
etching process in Example 2 by use of the scanning probe
microscope is displayed on a display.
[0038] FIG. 6B is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer treated to have a shape of chevrons by a second
annealing process after the etching process in Example 2 by use of
the scanning probe microscope is displayed on a display.
[0039] FIG. 6C is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold formed by the electroforming in Example 2 by use of the
scanning probe microscope is displayed on a display.
[0040] FIG. 6D is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
diffraction grating obtained in Example 2 by use of the scanning
probe microscope is displayed on a display.
[0041] FIG. 6E is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex
cross-section of the diffraction grating obtained in Example 2 by
use of the scanning probe microscope is displayed on a display.
[0042] FIG. 6F is a photograph showing a Fourier-transformed image,
in which a result of two-dimensional fast Fourier transform
processing conducted on a concavity and convexity analysis image,
which was obtained by use of the atomic force microscope, of the
surface of the diffraction grating obtained in Example 2, is
displayed on a display.
[0043] FIG. 6G is a graph showing a relation between a current
efficiency and a luminance L' of an organic EL element obtained in
Example 2.
[0044] FIG. 6H is a graph showing a relation between a power
efficiency and the luminance L' of the organic EL element obtained
in Example 2.
[0045] FIG. 7A is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by the
etching process in Example 3 by use of the scanning probe
microscope is displayed on a display.
[0046] FIG. 7B is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer treated to have the shape of chevrons by the second
annealing process after the etching process in Example 3 by use of
the scanning probe microscope is displayed on a display.
[0047] FIG. 7C is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
diffraction grating obtained in Example 3 by use of the scanning
probe microscope is displayed on a display.
[0048] FIG. 7D is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex
cross-section of the diffraction grating obtained in Example 3 by
use of the scanning probe microscope is displayed on a display.
[0049] FIG. 7E is a photograph showing a Fourier-transformed image,
in which a result of two-dimensional fast Fourier transform
processing conducted on a concavity and convexity analysis image,
which was obtained by use of the atomic force microscope, of the
surface of the diffraction grating obtained in Example 3, is
displayed on a display.
[0050] FIG. 8A is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by the
etching process in Example 4 by use of the scanning probe
microscope is displayed on a display.
[0051] FIG. 8B is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer treated to have the shape of chevrons by the second
annealing process after the etching process in Example 4 by use of
the scanning probe microscope is displayed on a display.
[0052] FIG. 8C is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
diffraction grating obtained in Example 4 by use of the scanning
probe microscope is displayed on a display.
[0053] FIG. 8D is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex
cross-section of the diffraction grating obtained in Example 4 by
use of the scanning probe microscope is displayed on a display.
[0054] FIG. 8E is a photograph showing a Fourier-transformed image,
in which a result of two-dimensional fast Fourier transform
processing conducted on a concavity and convexity analysis image,
which was obtained by use of the atomic force microscope, of the
surface of the diffraction grating obtained in Example 4, is
displayed on a display.
[0055] FIG. 8F is a graph showing a relation between a current
efficiency and a luminance L' of an organic EL element obtained in
Example 4.
[0056] FIG. 8G is a graph showing a relation between a power
efficiency and the luminance L' of the organic EL element obtained
in Example 4.
[0057] FIG. 9A is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
diffraction grating obtained in Example 5 by use of the scanning
probe microscope is displayed on a display.
[0058] FIG. 9B is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex
cross-section of the diffraction grating obtained in Example 5 by
use of the scanning probe microscope is displayed on a display.
[0059] FIG. 9C is a photograph showing a Fourier-transformed image,
in which a result of two-dimensional fast Fourier transform
processing conducted on a concavity and convexity analysis image,
which was obtained by use of the atomic force microscope, of the
surface of the diffraction grating obtained in Example 5, is
displayed on a display.
[0060] FIG. 10A is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by the
etching process in Example 6 by use of the scanning probe
microscope is displayed on a display.
[0061] FIG. 10B is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold formed by the electroforming in Example 6 by use of the
scanning probe microscope is displayed on a display.
[0062] FIG. 10C is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
diffraction grating obtained in Example 6 by use of the scanning
probe microscope is displayed on a display.
[0063] FIG. 10D is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex
cross-section of the diffraction grating obtained in Example 6 by
use of the scanning probe microscope is displayed on a display.
[0064] FIG. 10E is a photograph showing a Fourier-transformed
image, in which a result of two-dimensional fast Fourier transform
processing conducted on a concavity and convexity analysis image,
which was obtained by use of the atomic force microscope, of the
surface of the diffraction grating obtained in Example 6, is
displayed on a display.
[0065] FIG. 11A is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by the
etching process in Example 7, by use of the scanning probe
microscope is displayed on a display.
[0066] FIG. 11B is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
diffraction grating obtained in Example 7, by use of the scanning
probe microscope is displayed on a display.
[0067] FIG. 11C is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex
cross-section of the diffraction grating obtained in Example 7, by
use of the scanning probe microscope is displayed on a display.
[0068] FIG. 11D is a photograph showing a Fourier-transformed
image, in which a result of two-dimensional fast Fourier transform
processing conducted on a concavity and convexity analysis image,
which was obtained by use of the atomic force microscope, of the
surface of the diffraction grating obtained in Example 7, is
displayed on a display.
[0069] FIG. 12A is a transmission electron micrograph of a
cross-section of a coating film after the first annealing process
obtained in Example 8.
[0070] FIG. 12B is a scanning electron micrograph, of a
cross-section of a nickel mold from which a polymer component has
been removed in Example 8.
[0071] FIG. 12C is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by the
etching process in Example 8 by use of the scanning probe
microscope is displayed on a display.
[0072] FIG. 12D is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold formed by the electroforming in Example 8 by use of the
scanning probe microscope is displayed on a display.
[0073] FIG. 12E is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of
the diffraction grating obtained in Example 8 by use of the
scanning probe microscope is displayed on a display.
[0074] FIG. 12F is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex
cross-section of the diffraction grating obtained in Example 8 by
use of the scanning probe microscope is displayed on a display.
[0075] FIG. 12G is a photograph showing a Fourier-transformed
image, in which a result of two-dimensional fast Fourier transform
processing conducted on a concavity and convexity analysis image,
which was obtained by use of the atomic force microscope, of the
surface of the diffraction grating obtained in Example 8, is
displayed on a display.
[0076] FIG. 13A is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by the
etching process in Example 9 by use of the scanning probe
microscope is displayed on a display.
[0077] FIG. 13B is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer treated to have the shape of chevrons by the second
annealing process after the etching process in Example 9 by use of
the scanning probe microscope is displayed on a display.
[0078] FIG. 13C is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold formed by the electroforming in Example 9 by use of the
scanning probe microscope is displayed on a display.
[0079] FIG. 13D is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
diffraction grating obtained in Example 9 by use of the scanning
probe microscope is displayed on a display.
[0080] FIG. 13E is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex
cross-section of the diffraction grating obtained in Example 9 by
use of the scanning probe microscope is displayed on a display.
[0081] FIG. 13F is a photograph showing a Fourier-transformed
image, in which a result of two-dimensional fast Fourier transform
processing conducted on a concavity and convexity analysis image,
which was obtained by use of the atomic force microscope, of the
surface of the diffraction grating obtained in Example 9, is
displayed on a display.
[0082] FIG. 14A is a scanning electron micrograph of a
cross-section of a nickel mold obtained in Comparative Example
1.
[0083] FIG. 14B is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by the
etching process in Comparative Example 1 by use of the scanning
probe microscope is displayed on a display.
[0084] FIG. 14C is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold formed by the electroforming in Comparative Example 1 by use
of the scanning probe microscope is displayed on a display.
[0085] FIG. 15A is a scanning electron micrograph of a
cross-section of a nickel mold obtained in Comparative Example
2.
[0086] FIG. 15B is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by the
etching process in Comparative Example 2 by use of the scanning
probe microscope is displayed on a display.
[0087] FIG. 15C is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold formed by the electroforming in Comparative Example 2 by use
of the scanning probe microscope is displayed on a display.
[0088] FIG. 16A is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by the
etching process in Comparative Example 3 by use of the scanning
probe microscope is displayed on a display.
[0089] FIG. 16B is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold formed by the electroforming in Comparative Example 3 by use
of the scanning probe microscope is displayed on a display.
[0090] FIG. 17A is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by the
etching process in Comparative Example 4 by use of the scanning
probe microscope is displayed on a display.
[0091] FIG. 17B is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold formed by the electroforming in Comparative Example 4 by use
of the scanning probe microscope is displayed on a display.
[0092] FIG. 18 is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold formed by the electroforming in Comparative Example 5 by use
of the scanning probe microscope is displayed on a display.
[0093] FIG. 19 is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold formed by the electroforming in Comparative Example 6 by use
of the scanning probe microscope is displayed on a display.
[0094] FIG. 20 is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold formed by the electroforming in Comparative Example 7 by use
of the scanning probe microscope is displayed on a display.
[0095] FIG. 21A is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
block copolymer from which PMMA has been selectively removed by the
etching process in Comparative Example 8 by use of the scanning
probe microscope is displayed on a display.
[0096] FIG. 21B is a photograph showing an analysis image, in which
a result of analysis conducted on a concave and convex surface of a
mold formed by the electroforming in Comparative Example 8 by use
of the scanning probe microscope is displayed on a display.
[0097] FIG. 22 is a schematic illustration showing a stacked
structure of an organic EL element, in which a diffraction grating
obtained by the producing method of Example 10 is used.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0098] Hereinbelow, preferred embodiments of the present invention
will be described in detail with reference to the drawings.
[0099] At first, an explanation will be made about a method for
producing a mold suitable for producing a diffraction grating used
for an organic EL element and the like. As shown in the flowchart
of FIG. 3, the method for producing the mold mainly includes a step
(processing) of preparing a block copolymer solution, a step for
applying the block copolymer solution, a drying step, a first
heating step, an etching step, a second heating step, a seed layer
forming step, an electroforming step, and a releasing or peeling
step. Hereinafter, an explanation will be made about each step and
each subsequent step of the method for producing the mold with
reference to schematic illustrations of FIGS. 1 and 2 as
appropriate.
<Preparation Step of Block Copolymer Solution>
[0100] The block copolymer used for the present invention includes
at least a first polymer segment made of a first homopolymer and a
second polymer segment made of a second homopolymer different from
the first homopolymer. The second homopolymer desirably has a
solubility parameter which is higher than a solubility parameter of
the first homopolymer by 0.1 to 10 (cal/cm.sup.3).sup.1/2. In a
case that the difference between the solubility parameters of the
first and second homopolymers is less than 0.1
(cal/cm.sup.3).sup.1/2, it is difficult to form a regular micro
phase separation structure of the block copolymer. In a case that
the difference exceeds 10 (cal/cm.sup.3).sup.1/2, it is difficult
to prepare a uniform solution of the block copolymer.
[0101] Examples of monomers serving as raw materials of
homopolymers usable as the first homopolymer and second homopolymer
include styrene, methylstyrene, propylstyrene, butylstyrene,
hexylstyrene, octylstyrene, methoxystyrene, ethylene, propylene,
butene, hexene, acrylonitrile, acrylamide, methyl methacrylate,
ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl
methacrylate, octyl methacrylate, methyl acrylate, ethyl acrylate,
propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate,
methacrylic acid, acrylic acid, hydroxyethyl methacrylate,
hydroxyethyl acrylate, ethylene oxide, propylene oxide,
dimethylsiloxane, lactic acid, vinylpyridine, hydroxystyrene,
styrenesulfonate, isoprene, butadiene, .epsilon.-caprolactone,
isopropylacrylamide, vinyl chloride, ethylene terephthalate,
tetrafluoroethylene, and vinyl alcohol. Of these monomers, styrene,
methyl methacrylate, ethylene oxide, butadiene, isoprene,
vinylpyridine, and lactic acid are preferably used from the
viewpoints that the formation of phase separation easily occurs,
and that the concavities and convexities are easily formed by an
etching.
[0102] In addition, examples of a combination of the first
homopolymer and the second homopolymer include combinations of two
selected from the group consisting of a styrene-based polymer (more
preferably polystyrene), polyalkyl methacrylate (more preferably
polymethyl methacrylate), polyethylene oxide, polybutadiene,
polyisoprene, polyvinylpyridine, and polylactic acid. Of these
combinations, a combination of the styrene-based polymer and
polyalkyl methacrylate, a combination of the styrene-based polymer
and polyethylene oxide, a combination of the styrene-based polymer
and polyisoprene, a combination of the styrene-based polymer and
polybutadiene are more preferable, and the combination of the
styrene-based polymer and polymethyl methacrylate, the combination
of the styrene-based polymer and polyisoprene, the combination of
the styrene-based polymer and polybutadiene are particularly
preferable, from the viewpoint that the depths of the concavities
and convexities formed in the block copolymer can be further
increased by preferentially removing one of the homopolymers by the
etching process. A combination of polystyrene (PS) and polymethyl
methacrylate (PMMA) is further preferable.
[0103] The number average molecular weight (Mn) of the block
copolymer is preferably 500,000 or more, and is more preferably
1,000,000 or more, and particularly preferably 1,000,000 to
5,000,000. In a case that the number average molecular weight is
less than 500,000, the average pitch of the concavities and
convexities formed by the micro phase separation structure of the
block copolymer is so small that the average pitch of the
concavities and convexities of the obtained diffraction grating
becomes insufficient. Especially, in a case of the diffraction
grating used for the organic EL element, since the diffraction
grating needs to diffract illumination light over a range of
wavelength of a visible region, the average pitch is desirably 100
to 600 nm, and thus the number average molecular weight (Mn) of the
block copolymer is preferably 500,000 or more. Further, according
to experiments conducted by the inventors of the present invention,
it has been appreciated that, in a case that the number average
molecular weight (Mn) of the block copolymer is 500,000 or more, a
desired concavity and convexity pattern can not be obtained by an
electroforming, unless the second heating step is performed after
the etching step, as it will be described later.
[0104] The molecular weight distribution (Mw/Mn) of the block
copolymer is preferably 1.5 or less, and is more preferably 1.0 to
1.35. In a case that the molecular weight distribution exceeds 1.5,
it is difficult to form the regular micro phase separation
structure of the block copolymer.
[0105] Note that the number average molecular weight (Mn) and the
weight average molecular weight (Mw) of the block copolymer are
values measured by gel permeation chromatography (GPC) and
converted to molecular weights of standard polystyrene.
[0106] In the block copolymer, a volume ratio between the first
polymer segment and the second polymer segment (the first polymer
segment: the second polymer segment) is desirably 3:7 to 7:3 in
order to create a lamellar structure by self-organization or
assembly, and is more preferably 4:6 to 6:4. In a case that the
volume ratio is out of the above-described range, a concavity and
convexity pattern owing to the lamellar structure is difficult to
form.
[0107] The block copolymer solution used in the present invention
is prepared by dissolving the block copolymer in a solvent.
Examples of the solvent include aliphatic hydrocarbons such as
hexane, heptane, octane, decane, and cyclohexane; aromatic
hydrocarbons such as benzene, toluene, xylene, and mesitylene;
ethers such as diethyl ether, tetrahydrofuran, and dioxane; ketones
such as acetone, methyl ethyl ketone, isophorone, and
cyclohexanone; ether alcohols such as butoxyethyl ether,
hexyloxyethyl alcohol, methoxy-2-propanol, and benzyloxyethanol;
glycol ethers such as ethylene glycol dimethyl ether, diethylene
glycol dimethyl ether, triglyme, propylene glycol monomethyl ether,
and propylene glycol monomethyl ether acetate; esters such as ethyl
acetate, ethyl lactate, and .gamma.-butyrolactone; phenols such as
phenol and chlorophenol; amides such as N,N-dimethylformamide,
N,N-dimethylacetamide, and N-methylpyrrolidone; halogen-containing
solvents such as chloroform, methylene chloride, tetrachloroethane,
monochlorobenzene, and dichlorobenzene; hetero-element containing
compounds such as carbon disulfide; and mixture solvents thereof. A
percentage content of the block copolymer in the block copolymer
solution is preferably 0.1 to 15% by mass, and more preferably 0.3
to 5% by mass, relative to 100% by mass of the block copolymer
solution.
[0108] In addition, the block copolymer solution may further
include a different homopolymer (a homopolymer other than the first
homopolymer and the second homopolymer in the block copolymer
contained in the solution: for example, when the combination of the
first homopolymer and the second homopolymer in the block copolymer
is the combination of polystyrene and polymethyl methacrylate, the
different homopolymer may be any kind of homopolymer other than
polystyrene and polymethyl methacrylate), a surfactant, an ionic
compound, an anti-foaming agent, a leveling agent, and the
like.
[0109] By containing the different homopolymer, the micro phase
separation structure of the block copolymer can be improved. For
example, polyalkylene oxide can be used to increase the depths of
the concavities and convexities formed by the micro phase
separation structure. As the polyalkylene oxide, polyethylene oxide
or polypropylene oxide is more preferable, and polyethylene oxide
is particularly preferable. In addition, as the polyethylene oxide,
one represented by the following formula is preferable:
HO--(CH.sub.2--CH.sub.2--O).sub.n--H
[in the formula, n represents an integer of 10 to 5000 (more
preferably an integer of 50 to 1000, and further preferably an
integer of 50 to 500)]. In a case that the value of n is less than
the lower limit, the molecular weight is so low that the effect
obtained by containing the different homopolymer becomes
insufficient, because the polyethylene oxide is lost due to
volatilization, vaporization, or the like during a heating process
at a high-temperature. In a case that the value exceeds the upper
limit, the molecular weight is so high that the molecular mobility
is low. Hence, the speed of the phase separation is lowered, and
the formation of the micro phase separation structure is adversely
affected.
[0110] In addition, the number average molecular weight (Mn) of the
different homopolymer is preferably 460 to 220,000, and is more
preferably 2,200 to 46,000. In a case that the number average
molecular weight is less than the lower limit, the molecular weight
is so low that the effect obtained by containing the different
homopolymer becomes insufficient, because the different homopolymer
is lost due to volatilization, vaporization, or the like during the
heating process at the high-temperature. In a case that the number
average molecular weight exceeds the upper limit, the molecular
weight is so high that the molecular mobility is low. Hence, the
speed of the phase separation is lowered, and the formation of the
micro phase separation structure is adversely affected.
[0111] The molecular weight distribution (Mw/Mn) of the different
homopolymer is preferably 1.5 or less, and more preferably 1.0 to
1.3. In a case that the molecular weight distribution exceeds the
upper limit, uniformity of the shape of the micro phase separation
is less likely to be maintained. Note that the number average
molecular weight (Mn) and the weight average molecular weight (Mw)
are values measured by gel permeation chromatography (GPC) and
converted to molecular weights of standard polystyrene.
[0112] In addition, when the different homopolymer is used in the
present invention, it is preferable that the combination of the
first homopolymer and the second homopolymer in the block copolymer
be the combination of polystyrene and polymethyl methacrylate
(polystyrene-polymethyl methacrylate), and that the different
homopolymer be a polyalkylene oxide. By using a
polystyrene-polymethyl methacrylate block copolymer and
polyalkylene oxide in combination as described above, the
orientation in the vertical direction is further improved, thereby
making it possible to further increase the depths of the
concavities and convexities on the surface, and to shorten the
heating process time during the manufacture.
[0113] In a case that the different homopolymer is used, the
content thereof is preferably 100 parts by mass or less, and more
preferably 5 parts by mass to 100 parts by mass, relative to 100
parts by mass of the block copolymer. In a case that the content of
the different homopolymer is less than the lower limit, the effect
obtained by containing the different homopolymer becomes
insufficient.
[0114] In a case that the surfactant is used, the content thereof
is preferably 10 parts by mass or less relative to 100 parts by
mass of the block copolymer. Moreover, in a case that the ionic
compound is used, the content thereof is preferably 10 parts by
mass or less relative to 100 parts by mass of the block
copolymer.
[0115] In a case that the block copolymer solution contains the
different homopolymer, the total percentage content of the block
copolymer and the different homopolymer is preferably 0.1 to 15% by
mass, and more preferably 0.3 to 5% by mass, in the block copolymer
solution. In a case that the total percentage content is less than
the lower limit, it is difficult to uniformly apply the solution to
attain a film thickness sufficient to obtain a necessary film
thickness. In a case that the total percentage content exceeds the
upper limit, it is relatively difficult to prepare a solution in
which the block copolymer and the different homopolymer are
uniformly dissolved in the solvent.
<Application Step of Block Copolymer Solution>
[0116] According to the method for producing the mold of the
present invention, as shown in FIG. 1A, the block copolymer
solution prepared as described above is applied on a base member 10
to form a thin film 30. The base member 10 is not especially
limited, and is exemplified, for example, by substrates of resins
such as polyimide, polyphenylene sulfide (PPS), polyphenylene
oxide, polyether ketone, polyethylene naphthalate, polyethylene
terephthalate, polyarylate, triacetyl cellulose, and
polycycloolefin; inorganic substrates such as glass,
octadecyldimethyl chlorosilane (ODS) treated glass, octadecyl
trichlorosilane (OTS) treated glass, organo silicate treated glass,
and silicon substrates; and substrates of metals such as aluminum,
iron, and copper. In addition, the base member 10 may be subjected
to surface treatments such as an orientation treatment. By
performing treatment on the surface of the substrate such as the
glass with ODS, organo silicate or the like, the micro phase
separation structure such as the lamellar structure, a cylinder
structure, and a globular or spherical structure is more likely to
be arranged perpendicular to the surface in a heating step as will
be described later on. The reason thereof is that domain of each
block forming the block copolymer is more likely to be
perpendicularly-oriented by decreasing the difference in interface
energy between each block copolymer component and the surface of
the substrate.
[0117] The method for applying the block copolymer solution is not
particularly limited, and, for example, a spin coating method, a
spray coating method, a dip coating method, a dropping method, a
gravure printing method, a screen printing method, a relief
printing method, a die coating method, a curtain coating method, or
an ink jet method can be employed as the method.
[0118] The thickness of the thin film 30 of the block copolymer is
preferably within a range which allows the thickness of a dried
coating film, as will be described later, to be 10 to 3000 nm, and
more preferably within a range which allows the thickness of the
dried coating film to be 50 to 500 nm.
<Drying Step>
[0119] After the block copolymer solution is applied on the base
member 10 to form the thin film 30, the thin film 30 on the base
member 10 is dried. The drying can be performed in the ambient
atmosphere. The temperature for drying the thin film 30 is not
particularly limited, provided that the solvent can be removed from
the thin film 30. For example, the temperature is preferably 30
degrees Celsius to 200 degrees Celsius, and more preferably 40
degrees Celsius to 100 degrees Celsius. It is noted that
concavities and convexities are found, in some cases, on the
surface of the thin film 30 when the formation of the micro phase
separation structure of the block copolymer is started during the
drying step.
<First Heating Step>
[0120] After the drying step, the thin film 30 is heated at a
temperature of not less than a glass transition temperature (Tg) of
the block copolymer (first heating step or annealing process). The
heating step promotes the self-organization or assembly of the
block copolymer, and the micro phase separation of the block
copolymer into portions of a first polymer segment 32 and second
polymer segment 34 occurs as shown in FIG. 1B. In a case that the
heating temperature is less than the glass transition temperature
of the block copolymer, the molecular mobility of the polymer is so
low that the self-organization or assembly of the block copolymer
does not make progress adequately and thus the micro phase
separation structure can not be formed enough or the heating time
required for sufficiently generating the micro phase separation
structure is long. In addition, the upper limit of the heating
temperature is not particularly limited, unless the block copolymer
is pyrolyzed at the temperature. The first heating step can be
performed in the ambient atmosphere using an oven or the like. The
drying step and the heating step can be performed continuously by
gradually increasing the heating temperature. Accordingly, the
drying step is included in the heating step.
<Etching Step>
[0121] After the first heating step, the etching process of the
thin film 30 is performed. Since the molecular structure of the
first polymer segment 32 is different from the molecular structure
of the second polymer segment 34, etchability of the first polymer
segment 32 is also different from that of the second polymer
segment 34. Therefore, by performing the etching process depending
on each type of the polymer segments, that is, depending on each
type of homopolymer, it is possible to selectively remove one of
the polymer segments (second polymer segment 34) forming the block
copolymer. A remarkable concavity and convexity structure appears
on the coating film by removing each second polymer segment 34 from
the micro phase separation structure in the etching process, as
shown in FIG. 1C schematically. As the etching process, an etching
method using, for example, a reactive ion etching method, an ozone
oxidation method, a hydrolysis method, a metal ion staining method,
an ultraviolet-ray etching method, or the like can be employed.
Moreover, as the etching process, a method may be employed in which
covalent bonds in the block copolymer are cleaved by treating the
covalent bonds with at least one selected from the group consisting
of acids, bases, and reducing agents, and then the coating film in
which the micro phase separation structure is formed is cleaned
with a solvent which dissolves only one of the polymer segments, or
the like, thereby removing only the one of the polymer segments,
while keeping the micro phase separation structure. In the
embodiment(s) which will be described later, the ultraviolet-ray
etching is used in view of operability and the like.
<Second Heating Step>
[0122] The second heating process or the annealing process is
performed to a concavity and convexity structure 36 of the thin
film 30 obtained by the etching step. The heating temperature in
the second heating process is desirably not less than the glass
transition temperature of the first polymer segment 32 remaining
after the etching, that is, not less than the glass transition
temperature of the first homopolymer. For example, the heating
temperature in the second heating process is desirably not less
than the glass transition temperature of the first homopolymer and
not more than a temperature higher than the glass transition
temperature of the first homopolymer by 70 degrees Celsius. In a
case that the heating temperature is less than the glass transition
temperature of the first homopolymer, it is not possible to obtain
a desired concavity and convexity structure (that is, a smooth
chevron structure) after the electroforming, or a long time is
required to perform the heating. In a case that the heating
temperature is much higher than the glass transition temperature of
the first homopolymer, the first polymer segment 32 is melted
and/or the shape of the first polymer segment 32 is collapsed
severely. Thus, it is not preferable. In view of the above, the
heating is desirably performed within a range from the glass
transition temperature to the temperature higher than the glass
transition temperature by about 70 degrees Celsius. Similar to the
first heating process, the second heating process can be performed
in the ambient atmosphere using the oven or the like.
[0123] According to experiments of the inventors of the present
invention, it has been found out that a desired transfer pattern
can not be obtained in case that the concavity and convexity
structure 36 of the coating film obtained by the etching step is
used as a master (master block) to transfer the concavity and
convexity structure to a metallic mold by the electroforming which
will be described later. Especially, this problem becomes
conspicuous as the molecular weight of the block copolymer is
higher. As described above, the molecular weight of the block
copolymer is deeply linked with the micro phase separation
structure, and thus the pitch of the diffraction grating obtained
therefrom. Therefore, in a case that the diffraction grating is
used for a purpose such as the organic EL element, a distribution
of the pitch is required to be such that diffraction occurs in a
wavelength region such as the visible region including a wavelength
range which is wide and includes relatively long wavelength. In
order to realize this, even when a block copolymer having a
relatively high molecular weight is used, it is necessary to
reliably obtain, by the electroforming, a concavity and convexity
structure having the desired pitch distribution. In the present
invention, by performing the heating process for the concavity and
convexity structure obtained by the etching, a metallic mold, in
which the concavity and convexity structure is also reflected
enough, is successfully obtained in the subsequent electroforming
step.
[0124] The reason thereof is considered by the inventors as
follows. As shown in FIG. 1C conceptually, the concavity and
convexity structure 36 after the etching is considered to have a
complicated cross-section structure, in which the side surfaces of
grooves defined by the concavity and convexity structure are coarse
and the concavities and convexities (including the overhang) are
generated in a direction perpendicular to a thickness direction.
The following three problems are arisen by the complicated
cross-section structure.
i) In the complicated cross-section structure, a portion at which a
seed layer for the electroforming is not attached is generated, and
thereby making it difficult to uniformly accumulate the metal layer
by the electroforming. As a result, it is considered that the
obtained mold has low mechanical strength and that defects such as
deformation of the mold and pattern defect are caused. ii) In the
electroforming (electroplating), a thickness of plating varies
depending on shapes of respective parts of an object to be
subjected to the plating. In particular, a plated metal is more
likely to be attracted to convex portions and projecting or
prominent corners of the object, and is less likely to be attracted
to concave portions and hollow portions of the object. Also for
these reasons, it is difficult to obtain an electroformed film
having a uniform film thickness on the complicated concave and
convex cross-section structure after the etching. iii) Even when
the complicated cross-section structure as described above can be
transferred to the mold by the electroforming, in a case that the
concavity and convexity shape is tried to be transferred by
pressing the mold against a curable resin, the curable resin enters
gaps in the complicated cross-section structure of the mold. Hence,
the mold can not be released from the cured resin, or the pattern
defect occurs by fracture of the portion of the mold having the low
strength. Conventionally, the transfer has been repeated using
polydimethylsiloxane (PDMS) to prevent the above problem.
[0125] In the present invention, the first polymer segment 32
constructing the side surfaces of the grooves is subjected to the
annealing process by heating the concavity and convexity structure
after the etching. Thereby, as shown in FIG. 1D conceptually, each
cross-section shape defined by the first polymer segment 32 is
formed of a relatively smooth and sloped surface to have a shape of
chevron narrowing upward from the base member (referred to as
"chevron-shaped structure" in this invention). The overhang does
not appear in such chevron-shaped structure, and the chevron-shaped
structure is duplicated into the inverted pattern in a metal layer
accumulated on the first polymer segment 32, thereby the metal
layer can be released easily. It has become clear that the three
problems can be solved by such effects of the second heating step
as described above. FIG. 5B is a micrograph, taken by a scanning
electron microscope (SEM), showing the cross-section structure of
the mold, which is formed, by Ni-electroforming using the concavity
and convexity structure obtained by the heating process after the
etching process of the block copolymer, in Example 1 which will be
described later. The concavities and convexities are smooth, each
convex portion has the gentle chevron shape, and no overhang is
observed. On the other hand, FIG. 14B is a SEM micrograph showing
the cross-section structure of the mold, which is formed by the
Ni-electroforming (nickel electroforming) using the concavity and
convexity structure obtained without the second heating process
after the etching process of the block copolymer, in Comparative
Example 1 which will be described later. It has been appreciated
that Ni portions corresponding to white portions in FIG. 14B form
grooves each having a complicated shape including an overhang
structure; and that the resins (black portions in FIG. 14B) are
penetrated or entered into the grooves.
[0126] The base member 10, which has a chevron-shaped structure 38
obtained in the second heating step, is used as a master for
transfer in subsequent steps. The average pitch of the concavities
and convexities representing the chevron-shaped structure 38 is
preferably within a range from 100 to 600 nm, and more preferably
200 to 600 nm. In a case that the average pitch of the concavities
and convexities is less than the lower limit, the pitches are so
small relative to wavelengths of the visible light that required
diffraction of the visible light is less likely to occur by using
the diffraction grating obtained by use of such a master. In a case
that the average pitch exceeds the upper limit, the diffraction
angle of the diffraction grating obtained by use of such a master
is so low that functions as the diffraction grating can not be
fulfilled sufficiently. Note that the average pitch of the
concavities and convexities refers to an average value of pitches
of the concavities and convexities obtained when pitches of the
concavities and convexities on the surface of the cured resin layer
(distances between adjacent concave portions or between adjacent
convex portions) are measured. In addition, a value which can be
calculated as follows is employed as such average value of the
pitches of the concavities and convexities. A concavity and
convexity analysis image is obtained by measuring the shape of the
concavities and convexities on the surface by use of a scanning
probe microscope (for example, one manufactured by SII Nano
Technology Inc., under the product name of "E-sweep", or the like),
then the distances between randomly selected adjacent convex
portions or the distances between randomly selected adjacent
concave portions are measured at 100 points or more in the
concavity and convexity analysis image, and then an average of
these distances is determined as the average value of the pitches
of concavities and convexities.
[0127] In addition, the average height of the concavities and
convexities representing the chevron-shaped structure 38 is
preferably within a range from 5 to 200 nm, more preferably within
a range from 20 to 200 nm, and further preferably within a range
from 50 to 150 nm. In a case that the average height of the
concavities and convexities is less than the lower limit, the
height is so small relative to the wavelengths of the visible light
that the diffraction is insufficient. In a case that the average
height exceeds the upper limit, the following tendency is found.
When the obtained diffraction grating is used as an optical element
on the light extraction port side of the organic EL element, the
element tends to be easily destructed and the life thereof tends to
be shortened because of heat generation which occurs when the
electric field distribution in the EL layer becomes non-uniform,
and hence electric fields concentrate on a certain position or
area. Note that the average height of the concavities and
convexities refers to an average value of the heights of the
concavities and convexities obtained when heights of the
concavities and convexities (the distances between concave portions
and convex portions in the depth direction) on the surface of the
cured resin layer are measured. In addition, a value calculated as
follows is employed as the average value of the heights of the
concavities and convexities. That is, a concavity and convexity
analysis image is obtained by measuring the shape of the
concavities and convexities on the surface by use of the scanning
probe microscope (for example, one manufactured by SII
NanoTechnology Inc., under the product name of "E-sweep", or the
like), then the distances between randomly selected concave
portions and convex portions in the depth direction are measured at
100 points or more in the concavity and convexity analysis image,
and then the average of the distances is determined as the average
value of heights of concavities and convexities.
<Seed Layer Forming Step and Electroforming Step>
[0128] As shown in FIG. 1E, a seed layer 40 functioning as an
electroconductive layer for a subsequent electroforming process is
formed on the surface of the chevron-shaped structure 38 of the
master obtained as described above. The seed layer 40 can be formed
by non-electrolytic plating, sputtering, or vapor deposition. The
thickness of the seed layer 40 is preferably not less than 10 nm
and more preferably not less than 100 nm to uniformalize current
density during the subsequent electroforming process, and thereby
making the thickness of the metal layer accumulated by the
subsequent electroforming process to be constant. As a material of
the seed layer, it is possible to use, for example, nickel, copper,
gold, silver, platinum, titanium, cobalt, tin, zinc, chrome,
gold-cobalt alloy, gold-nickel alloy, boron-nickel alloy, solder,
copper-nickel-chromium alloy, tin-nickel alloy, nickel-palladium
alloy, nickel-cobalt-phosphorus alloy, or alloy thereof. It is
considered that the relatively smooth chevron-shaped structure as
shown in FIG. 1D is more likely to be attached to by the seed layer
completely and with a uniform thickness, compared with the
complicated cross-section structure as shown in FIG. 1C.
[0129] Subsequently, the metal layer is accumulated on the seed
layer 40 by the electroforming (electroplating). The entire
thickness of a metal layer 50 including the thickness of the seed
layer 40 can be, for example, 10 to 3000 .mu.m. As a material of
the metal layer 50 accumulated by the electroforming, it is
possible to use any of metal species as described above which can
be used as the seed layer 40. In view of wear resistance as the
mold and peeling property, nickel is preferable. In this case,
nickel is also preferably used for the seed layer 40. The current
density during the electroforming may be, for example, 0.03 to 10
A/cm.sup.2 for suppressing bridge to form a uniform metal layer and
in view of shortening of an electroforming time. Considering ease
of the subsequent processes such as pressing to the resin layer,
peeling, and cleaning, the formed metal layer 50 desirably has
appropriate hardness and thickness. A diamond like carbon (DLC)
process or a Cr plating processing treatment can be performed on
the surface of the metal layer in order to improve the hardness of
the metal layer formed by the electroforming. Alternatively, the
hardness of the surface may be improved by further performing the
heating process of the metal layer.
<Peeling Step>
[0130] The metal layer 50 including the seed layer obtained as
described above is peeled off from the base member having the
concavity and convexity structure to obtain a mold as a father die.
As a peeling method, the metal layer 50 may be peeled off
physically, or the first homopolymer and the remained block
copolymer may be dissolved to be removed by using an organic
solvent dissolving them, such as toluene, tetrahydrofuran (THF),
and chloroform.
<Cleaning Step>
[0131] In a case that the mold is peeled off from the base member
10 having the chevron-shaped structure 38 as above-described, a
part of the polymer 60, like the first polymer segment, remains in
the mold in some cases as shown in FIG. 1G. In such a case, each
part 60 remained in the mold can be removed by a cleaning. As a
cleaning method, a wet cleaning or a dry cleaning can be used. As
the wet cleaning, the remained parts can be removed by performing
the cleaning with the organic solvent such as toluene and
tetrahydrofuran, the surfactant, or an alkaline solution. In a case
that the organic solvent is used, an ultrasonic cleaning may be
carried out. Alternatively, the remained parts may be removed by
performing an electrolytic cleaning. As the dry cleaning, the
remained parts can be removed by an ashing using ultraviolet rays
and/or plasma. The wet cleaning and the dry cleaning may be used in
combination. After the cleaning as described above, a rinse process
with pure water or purified water may be performed, and then ozone
irradiation may be carried out after a drying. Accordingly, a mold
70 having a desired concavity and convexity structure is
obtained.
[0132] Next, an explanation will be made about a method for
producing the diffraction grating used for the organic EL element
and the like using the obtained mold 70 with reference to FIG. 2A
to FIG. 2E.
<Mold-Release Treatment Step>
[0133] In a case that the concavity and convexity structure is
transferred to the resin using the mold 70, a mold-release
treatment of the mold 70 may be performed to improve the mold
releasability from the resin. As the mold-release treatment, a
manner to decrease surface energy is commonly used, and the
mold-release treatment is not particularly limited and includes,
for example, a method in which a concave and convex surface 70a of
the mold 70 is coated with a mold-release agent such as a
fluorine-based material and a silicon resin as shown in FIG. 2A, a
method in which the surface is subjected to a treatment using a
fluorine-based silane coupling agent, and a method in which a film
of a diamond like carbon is formed on the surface.
<Step for Transferring Mold to Resin Layer>
[0134] By using the obtained mold 70, a mother die is produced by
transferring the concavity and convexity structure (pattern) of the
mold to a layer formed of an organic material such as resin or an
inorganic material such as a sol-gel material. In the following
description, an explanation will be made by citing a resin layer 80
as a layer to which the concavity and convexity pattern is
transferred, as an example. In the method of the transfer process,
for example, the curable resin is applied on a transparent
supporting substrate 90, and then the resin layer 80 is cured while
pressing the concavity and convexity structure of the mold 70
against the resin layer 80, as shown in FIG. 2B. The transparent
supporting substrate 90 is exemplified, for example, by base
members made of a transparent inorganic substance such as glass;
base members made of a resin such as polyethylene terephthalate
(PET), polyethylene terenaphthalate (PEN), polycarbonate (PC),
cycloolefin polymer (COP), polymethyl methacrylate (PMMA), or
polystyrene (PS); stacked base members having a gas barrier layer
made of an inorganic substance such as SiN, SiO.sub.2, SiC,
SiO.sub.xN.sub.y, TiO.sub.2, or Al.sub.2O.sub.3 formed on the
surface of the base member made of any of the above-described
resins; and stacked base members having base members made of any of
the above-described resins and gas barrier layers made of any of
the above-described inorganic substances stacked alternately on
each other. In addition, the thickness of the transparent
supporting substrate may be within a range from 1 to 500 .mu.m.
[0135] Examples of the curable resin include epoxy resin, acrylic
resin, urethane resin, melamine resin, urea resin, polyester resin,
phenol resin, and cross-linking type liquid crystal resin. The
thickness of the cured resin is preferably within a range from 0.5
to 500 .mu.m. In a case that the thickness is less than the lower
limit, heights of the concavities and convexities formed on the
surface of the cured resin layer are more likely to be
insufficient. In a case that the thickness exceeds the upper limit,
an effect of volume change of the resin which occurs during upon
curing is likely to be so large that the formation of the shape of
the concavities and convexities tends to be insufficient.
[0136] As a method for applying the curable resin, it is possible
to adopt various coating methods such as a spin coating method, a
spray coating method, a dip coating method, a dropping method, a
gravure printing method, a screen printing method, a relief
printing method, a die coating method, a curtain coating method, an
ink-jet method, and a sputtering method. Moreover, the condition
for curing the curable resin varies depending on the kind of the
resin used. For example, a curing temperature is preferably within
a range from room temperature to 250 degrees Celsius, and a curing
time is preferably within a range from 0.5 minutes to 3 hours.
Alternatively, a method may be employed in which the curable resin
is cured by irradiation with energy rays such as ultraviolet rays
or electron beams. In such a case, the amount of the irradiation is
preferably within a range from 20 mJ/cm.sup.2 to 5 J/cm.sup.2.
[0137] Subsequently, the mold 70 is detached from the cured rein
layer 80 in a cured state. A method for detaching the mold 70 is
not limited to a mechanical peeling method, and can adopt any known
method. Then, as shown in FIG. 2C, it is possible to obtain a resin
film structure 100 in which the cured rein layer 80 having the
concavities and convexities is formed on the transparent supporting
substrate 90. The resin film structure 100 may be used, as it is,
as the diffraction grating. Alternatively, as will be described
later on, the resin film structure 100 is further used as the mold
to make a diffraction grating made of the organic material such as
the resin or a structure made of the inorganic material such as the
sol-gel material, and the structure made of the organic material or
the structure made of the inorganic material can be used as the
diffraction grating.
[0138] The method for producing the mold of the present invention
can be used not only in production of the diffraction grating
provided on the light extraction port side of the organic EL
element but also in production of an optical component having a
minute or fine pattern used for various devices. For example, the
method for producing the mold of the present invention can be used
to produce a wire grid polarizer, an antireflection film, or an
optical element for providing a light confinement effect in a solar
cell by being placed on the photoelectric conversion surface side
of the solar cell.
[0139] As described above, the resin film structure 100 having a
desired pattern can be obtained. In a case that the inverted
pattern of the resin film structure 100 is used as the diffraction
grating, the resin film structure 100 obtained through the transfer
process of the mold as described above is used as the mother die; a
curable resin layer 82 is applied on another transparent supporting
substrate 92 as shown in FIG. 2D; and the curable resin layer 82 is
cured while pressing the resin film structure 100 against the
curable resin layer 82, similar to a case in which the resin film
structure 100 is formed. Subsequently, the resin film structure 100
is peeled off from the curable resin layer 82 in a cured state.
Accordingly, a replica 110 as another resin film structure as shown
in FIG. 2E can be obtained. Further, it is allowable to produce a
replica having the inverted pattern of the replica 110 by
performing the above transfer step using the replica 110 as a
master and/or to produce a sub-replica by repeating the above
transfer step again using the replica having the inverted pattern
as the master.
[0140] Next, an explanation will be made about a method for
manufacturing a structure having concavities and convexities made
of the sol-gel material (hereinafter referred to as "sol-gel
structure" as appropriate) by further using the obtained resin film
structure 100 as the master. A method for forming a substrate
having a concavity and convexity pattern using the sol-gel material
mainly includes: a solution preparation step for preparing a sol
solution; an application step for applying the prepared sol
solution on the substrate; a drying step for drying the coating
film of the sol solution applied on the substrate; a pressing step
for pressing a mold with a transfer pattern; a pre-sintering step
during which the coating film to which the mold is pressed is
subjected to the pre-sintering; a peeling step for peeling off the
mold from the coating film; and a main sintering step during which
the coating film is subjected to the main sintering. Hereinbelow,
an explanation will be made about each of the steps
sequentially.
<Sol-Gel Solution Preparation Step>
[0141] At first, a sol-gel solution is prepared to form a coating
film to which a pattern is transferred by a sol-gel method. For
example, in a case that silica is synthesized by the sol-gel method
on the substrate, the sol solution of metal alkoxide (silica
precursor) is prepared. The silica precursor is exemplified by
metal alkoxides including, for example, tetraalkoxide monomers such
as tetramethoxysilane (TMOS), tetraethoxysilane (TEOS),
tetra-i-propoxysilane, tetra-n-propoxysilane, tetra-i-butoxysilane,
tetra-n-butoxysilane, tetra-sec-butoxysilane, and
tetra-t-butoxysilane; trialkoxide monomers such as methyl
trimethoxysilane, ethyl trimethoxysilane, propyl trimethoxysilane,
isopropyl trimethoxysilane, phenyl trimethoxysilane, methyl
triethoxysilane, ethyl triethoxysilane, propyl triethoxysilane,
isopropyl triethoxysilane, phenyl triethoxysilane, methyl
tripropoxysilane, ethyl tripropoxysilane, propyl tripropoxysilane,
isopropyl tripropoxysilane, phenyl tripropoxysilane, methyl
triisopropoxysilane, ethyl triisopropoxysilane, propyl
triisopropoxysilane, isopropyl triisopropoxysilane, phenyl
triisopropoxysilane; a polymer obtained by polymerizing the above
monomers in small amounts; and a composite material characterized
in that functional group and/or polymer is introduced into a part
of the material. Further, the silica precursor is exemplified, for
example, by metal acetylacetonate, metal carboxylate, oxychloride,
chloride, and mixtures thereof. The silica precursor, however, is
not limited thereto. Examples of metal species include, in addition
to Si, Ti, Sn, Al, Zn, Zr, In, and mixtures thereof, but are not
limited thereto. It is also possible to use any appropriate mixture
of precursors of the above oxidized metals.
[0142] In a case that a mixture of TEOS and MTES is used, the
mixture ratio thereof can be 1:1, for example, in a molar ratio.
The sol solution produces amorphous silica by performing hydrolysis
and polycondensation reaction. An acid such as hydrochloric acid or
an alkali such as ammonia is added in order to adjust pH of the
solution as a synthesis condition. The pH is preferably not more
than 4 or not less than 10. Water may be added to perform the
hydrolysis. An amount of water to be added can be 1.5 times or more
with respect to metal alkoxide species in the molar ratio.
[0143] Examples of the solvent include alcohols such as methanol,
ethanol, isopropyl alcohol (IPA), and butanol; aliphatic
hydrocarbons such as hexane, heptane, octane, decane, and
cyclohexane; aromatic hydrocarbons such as benzene, toluene,
xylene, and mesitylene; ethers such as diethyl ether,
tetrahydrofuran, and dioxane; ketones such as acetone, methyl ethyl
ketone, isophorone, and cyclohexanone; ether alcohols such as
butoxyethyl ether, hexyloxyethyl alcohol, methoxy-2-propanol, and
benzyloxyethanol; glycols such as ethylene glycol and propylene
glycol; glycol ethers such as ethylene glycol dimethyl ether,
diethylene glycol dimethyl ether, and propylene glycol monomethyl
ether acetate; esters such as ethyl acetate, ethyl lactate, and
.gamma.-butyrolactone; phenols such as phenol and chlorophenol;
amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and
N-methylpyrrolidone; halogen-containing solvents such as
chloroform, methylene chloride, tetrachloroethane,
monochlorobenzene, and dichlorobenzene; hetero-element containing
compounds such as carbon disulfide; water; and mixture solvents
thereof. Especially, ethanol and isopropyl alcohol are preferable.
Further, a mixture of water and ethanol and a mixture of water and
isopropyl alcohol are also preferable.
[0144] As an additive, it is possible to use, for example,
polyethylene glycol, polyethylene oxide, hydroxypropylcellulose,
and polyvinyl alcohol for viscosity adjustment; alkanolamine such
as triethanolamine as a solution stabilizer; .beta.-diketone such
as acetylacetone; .beta.-ketoester; formamid; dimetylformamide; and
dioxane.
[0145] The sol solution prepared as described above is applied on
the substrate. As the substrate, substrates made of inorganic
materials such as glass, silica glass, and silicon substrates or
substrates of resins such as polyethylene terephthalate (PET),
polyethylene terenaphthalate (PEN), polycarbonate (PC), cycloolefin
polymer (COP), polymethyl methacrylate (PMMA), polystyrene (PS),
polyimide (PI), and polyarylate may be used. The substrate may be
transparent or opaque. In a case that a substrate having a
concavity and convexity pattern obtained from the substrate is used
for production of the organic EL element as will be described
later, the substrate desirably has resistance to heat and
ultraviolet (UV) light etc. In view of this, the substrates made of
the inorganic materials such as the glass, the silica glass, and
the silicon substrates are more preferable. It is allowable to
perform a surface treatment or provide an easy-adhesion layer on
the substrate in order to improve adhesion property and to provide
a gas barrier layer in order to keep out moisture and/or gas such
as oxygen. As a method for applying the sol solution, it is
possible to use any application method such as a bar coating
method, a spin coating method, a spray coating method, a dip
coating method, a die coating method, and an ink-jet method. Among
the methods as described above, the bar coating method, the die
coating method, and the spin coating method are preferable, because
the sol solution can be uniformly applied on the substrate having a
relatively large area and the application can be quickly completed
prior to gelation of the sol solution. It is noted that, since a
desired concavity and convexity pattern by a sol-gel material layer
is formed in subsequent steps, the surface of the substrate
(including the surface treatment or the easy-adhesion layer in case
that the surface treatment or the easy-adhesion layer is present)
may be flat, and the substrate itself does not have the desired
concavity and convexity pattern.
[0146] After the application step, the substrate is kept in the
atmosphere or under reduced pressure to evaporate the solution in
the applied coating film (hereinafter referred to also as "sol-gel
material layer" as appropriate). Subsequently, the resin film
structure 100 (mold) is pressed against the coating film. In this
situation, the resin film structure 100 may be pressed by using a
pressing roll. A period of time during which the mold and the
coating film are brought in contact with each other in a roll
process is shorter than that in a pressing system, and thus there
are advantages such that it is possible to prevent deformation of
pattern due to difference among coefficients of thermal expansion
of the mold, the substrate, a stage on which the substrate is
provided, and the like; it is possible to prevent generation of
bubbles of gas in the pattern due to bumping of the solvent in the
gel solution or to prevent trace or mark of gas from being left; it
is possible to reduce transfer pressure and peeling force due to
line contact with the substrate (coating film), and thereby making
it possible to deal with a larger substrate readily; no bubble is
included during the pressing; and the like. Further, the heating
may be performed while pressing the resin film structure 100.
[0147] After the resin film structure 100 as the mold is pressed
against the coating film (sol-gel material layer), the coating film
may be subjected to the pre-sintering. The pre-sintering promotes
gelation of the coating film to solidify the pattern, and thereby
the pattern is less likely to be collapsed during the peeling. In a
case that the pre-sintering is performed, the heating is preferably
performed at a temperature from 40 degrees Celsius to 150 degrees
Celsius in the atmosphere. It is not indispensable to perform the
pre-sintering.
[0148] The resin film structure 100 is peeled off from the coating
film (sol-gel material layer) after the pressing step or the
pre-sintering step. In a case that the roll is used during the
pressing, the peeling force may be smaller than that in a case that
a plate-shaped mold is used, and it is possible to easily peel off
the mold from the coating film without remaining the coating film
in the mold.
[0149] After the resin film structure 100 is peeled off from the
coating film (sol-gel material layer) on the substrate, the coating
film is subjected to the main sintering. Hydroxyl group and the
like contained in silica (amorphous silica) forming the coating
film is desorbed or eliminated by the main sintering to further
strengthen the coating film. The main sintering may be performed at
a temperature from 200 degrees Celsius to 1200 degrees Celsius for
about 5 minutes to 6 hours. Accordingly, the coating film is cured,
and thereby obtaining a sol-gel structure (diffraction grating)
with a concavity and convexity pattern film which corresponds to
the concavity and convexity pattern of the resin film structure
100, that is, a sol-gel structure (diffraction grating) in which
the sol-gel material layer having the concavity and convexity
pattern is directly formed on the flat substrate. In this
situation, depending on a sintering temperature and a sintering
time, the silica as the sol-gel material layer is amorphous,
crystalline, or in a mixture state of the amorphous and the
crystalline.
[0150] In a case that the replica 110 (or sol-gel structure) is
duplicated using the resin film structure 100, or in a case that
another replica is duplicated using the obtained replica 110 (or
sol-gel structure), a film may be laminated or stacked, on the
surface of the resin film structure 100 or the replica 110 (or
sol-gel structure) having the concavity and convexity pattern, by a
gas phase method such as an evaporation method or a sputtering
method. By stacking the film as described above, in a case that
transfer etc. is performed with, for example, applying the resin
onto the surface of the film, the adhesion between the substrate
and the resin (for example, a UV curable resin) can be lowered, so
that the master block is more likely to be easily peeled. Examples
of the vapor-deposited film include metals such as aluminum, gold,
silver, platinum, and nickel; and metal oxides such as aluminum
oxide. In addition, the thickness of the vapor-deposited film is
preferably 5 to 500 nm. In a case that the thickness is less than
the lower limit, a uniform film is difficult to obtain, so that
sufficient effect of lowering the adhesion is decreased. In a case
that the thickness exceeds the upper limit, the shape of the master
block is more likely to be dull. In a case that the cured resin
layer of the resin film structure 100 or the replica 110 is made of
a UV curable resin, postcure may be conducted as appropriate by,
for example, ultraviolet light irradiation, after curing of the
resin.
[0151] In the steps shown in FIGS. 2B and 2D, the curable resins
80, 82 are applied on the transparent supporting substrates 90, 92,
respectively. In addition, it is allowable to use one obtained as
follows as the master block. The curable resin is applied directly
on the surface of the mold 70 which is the master block or the
surface of the cured resin layer 80, and then the cured resin is
detached. Alternatively, instead of applying the resin onto the
surface of the master block, it is allowable to employ, as the
master block, a concavity and convexity film of the cured resin
obtained as follows. That is, the master block is pressed onto the
coating film of the resin, and the resin is cured.
<Method for Producing Organic EL Element>
[0152] Next, an explanation will be made about a method for
producing an organic EL element using the resin film obtained as
described above or the diffraction grating which is the sol-gel
structure. Here, an explanation will be made by taking a method for
producing an organic EL element using a diffraction grating made of
a resin film 100 as an example, with reference to FIG. 4.
At first, as shown in FIG. 4, a transparent electrode denoted by a
reference numeral 3 is stacked on a resin layer 80 of the resin
film 100 to maintain a concavity and convexity structure formed on
the surface of the resin 80. As a material for the transparent
electrode 3, for example, indium oxide, zinc oxide, tin oxide,
indium-tin oxide (ITO), which is a composite material thereof,
gold, platinum, silver, or copper is used. Of these materials, ITO
is preferable from the viewpoint of the transparency and the
electrical conductivity. The thickness of the transparent electrode
3 is preferably within a range from 20 to 500 nm. In a case that
the thickness is less than the lower limit, the electrical
conductivity is more likely to be insufficient. In a case that the
thickness exceeds the upper limit, there is possibility that the
transparency is so insufficient that the emitted EL light cannot be
extracted to the outside sufficiently. As a method for stacking the
transparent electrode 3, any known method such as a vapor
deposition method or a sputtering method can be employed as
appropriate. Of these methods, the vapor deposition method is
preferably employed from the viewpoint of maintaining the shape of
the concavities and convexities formed on the surface of the cured
resin layer; and the sputtering method is preferably employed from
the viewpoint of improving adhesion property. It is allowable to
put a glass substrate on a side opposite to the resin layer 80 of
the resin film 100 before the transparent electrode 3 is provided
on the resin layer 80.
[0153] Next, an organic layer denoted by a reference numeral 4 as
shown in FIG. 4 is stacked on the transparent electrode 3 to
maintain the shape of the concavities and convexities formed on the
surface of the resin 80. The organic layer 4 is not particularly
limited, provided that the organic layer 4 is one usable as an
organic layer of the organic EL element. As the organic layer 4,
any known organic layer can be used as appropriate. The organic
layer 4 may be a stacked body of various organic thin films, and,
for example, may be a stacked body of an anode buffer layer 11, a
hole transporting layer 12, and an electron transporting layer 13
as shown in FIG. 4. Here, examples of materials for the anode
buffer layer 11 include copper phthalocyanine, PEDOT, and the like.
Examples of materials for the hole transporting layer 12 include
derivatives of triphenylamine, triphenyldiamine derivatives (TPD),
benzidine, pyrazoline, styrylamine, hydrazone, triphenylmethane,
carbazole, and the like. Examples of materials for the electron
transporting layer 13 include aluminum-quinolinol complex (Alq),
phenanthroline derivatives, oxadiazole derivatives, triazole
derivatives, phenylquinoxaline derivatives, silole derivatives, and
the like. The organic layer 4 may be, for example, a stacked body
of a hole injecting layer made of a triphenylamine derivative or
the like, and a light emitting layer made of a fluorescent organic
solid such as anthracene, a stacked body of the light emitting
layer and an electron injecting layer made of a perylene derivative
or the like, or a stacked body of these hole injecting layer, light
emitting layer, and electron injecting layer.
[0154] The organic layer 4 may be a stacked body of the hole
transporting layer, the light emitting layer, and the electron
transporting layer as exemplified in Example 22 as will be
described later on. In this case, examples of materials of the hole
transporting layer include aromatic diamine compounds such as
phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin
derivatives, N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine
(TPD), and
4,4'-bis[N-(naphthyl)-N-phenyl-amino]biphenyl(.alpha.-NPD);
oxazole; oxadiazole; triazole; imidazole; imidazolone; stilbene
derivatives; pyrazoline derivatives; tetrahydroimidazole;
polyarylalkane; butadiene; and
4,4',4''-tris(N-(3-methylphenyl)N-phenylamino)triphenylamine
(m-MTDATA). The materials of the hole transporting layer, however,
are not limited thereto. By providing the light emitting layer, a
hole injected from the transparent electrode and electron injected
from a metal electrode are recombined to occur light emission.
Examples of materials of the light emitting layer include
metallo-organic complex such as anthracene, naphthalene, pyrene,
tetracene, coronene, perylene, phthaloperylene, naphthaloperylene,
diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole,
bisbenzoxazoline, bisstyryl, cyclopentadiene, and
aluminum-quinolinol complex (Alq3); tri-(p-terphenyl-4-yl)amine;
1-aryl-2,5-di(2-thienyl) pyrrole derivatives; pyran; quinacridone;
rubren; distyrylbenzene derivatives; distyryl arylene derivatives;
distyryl amine derivatives; and various fluorescent pigments or
dyes. Further, it is preferable that light-emitting materials
selected from the above compounds are mixed as appropriate and then
are used. Furthermore, it is possible to preferably use a material
system generating emission of light from a spin multiplet, such as
a phosphorescence emitting material generating emission of
phosphorescence and a compound including, in a part of the
molecules, a constituent portion formed by the above materials. The
phosphorescence emitting material preferably includes heavy metal
such as iridium. A host material having high carrier mobility may
be doped with each of the light-emitting materials as a guest
material to generate the light emission using dipole-dipole
interaction (Forster mechanism), electron exchange interaction
(Dexer mechanism). Examples of materials of the electron
transporting layer include heterocyclic tetracarboxylic anhydrides
such as nitro-substituted fluorene derivatives, diphenylquinone
derivatives, thiopyran dioxide derivatives, and
naphthaleneperylene; and metallo-organic complex such as
carbodiimide, fluorenylidene methane derivatives, anthraquino
dimethane and anthrone derivarives, oxadiazole derivatives, and
aluminum-quinolinol complex (Alq3). Further, in the oxadiazole
derivatives mentioned above, it is also possible to use, as an
electron transporting material, thiadiazole derivatives in which
oxygen atoms of oxadiazole rings are substituted by sulfur atoms
and quinoxaline derivatives having quinoxaline rings known as
electron attractive group. Furthermore, it is also possible to use
a polymeric material in which the above materials are introduced
into a macromolecular chain or the above materials are made to be a
main chain of the macromolecular chain. It is noted that the hole
transporting layer or the electron transporting layer may also
function as the light-emitting layer. In this case, there are two
organic layers between the transparent electrode and the metal
electrode which will be described later.
[0155] From the viewpoint of facilitating charge injection or hole
injection into any organic layer 4, a layer made of a metal
fluoride such as lithium fluoride (LiF) or Li.sub.2O.sub.3, a
highly active alkaline earth metal such as Ca, Ba, or Cs, an
organic insulating material, or the like may be provided on the
transparent electrode 3 or the organic layer 4. In addition, from
the viewpoint of facilitating the hole injection from the
transparent electrode, a layer made of triazole derivatives;
oxadiazole derivatives; imidazole derivatives; polyarylalkane
derivatives; pyrazoline derivatives and pyrazolone derivatives;
phenylenediamine derivatives; arylamine derivatives;
amino-substituted chalcone derivatives; oxazole derivatives;
styrylanthracene derivatives; fluorenon derivatives; hydrazone
derivatives; stilbene derivatives; silazane derivatives; aniline
copolymer; or a conductive polymer oligomer, in particular,
thiophene oligomer, may be provided between the organic layer and
the transparent electrode as the hole injecting layer.
[0156] In a case that the organic layer 4 is a stacked body formed
of the anode buffer layer 11, the hole transporting layer 12, and
the electron transporting layer 13, the thicknesses of the anode
buffer layer 11, the hole transporting layer 12, and the electron
transporting layer 13 are preferably within a range from 1 to 50
nm, a range from 5 to 200 nm, and a range from 5 to 200 nm,
respectively, from the viewpoint of maintaining the shape of the
concavities and convexities formed on the surface of the cured
resin layer. In a case that the organic layer 4 is a stacked body
formed of the hole transporting layer, the light-emitting layer,
and the electron transporting layer, the thicknesses of the hole
transporting layer, the light-emitting layer, and the electron
transporting layer are preferably within a range from 1 to 200 nm,
a range from 5 to 100 nm, and a range from 5 to 200 nm,
respectively. As a method for stacking any organic layer 4, any
known method such as a vapor deposition method, a sputtering
method, and a die coating method can be employed as appropriate. Of
these methods, the vapor deposition method is preferably employed
from the viewpoint of maintaining the shape of the concavities and
convexities formed on the surface of the resin 80.
[0157] Subsequently, as shown in FIG. 4, a metal electrode denoted
by a reference numeral 5 is stacked on the organic layer 4 so as to
maintain the shape of the concavities and convexities formed on the
surface of the resin 80 in the step for forming the organic EL
element. Materials of the metal electrode 5 are not particularly
limited, and a substance having a small work function can be used
as appropriate. Examples of the materials include aluminum, MgAg,
MgIn, and AlLi. The thickness of the metal electrode 5 is
preferably within a range from 50 to 500 nm. In a case that the
thickness is less than the lower limit, the electrical conductivity
is more likely to be decreased. In a case that the thickness
exceeds the upper limit, there is possibility that the shape of the
concavities and convexities is difficult to maintain. Any known
method such as a vapor deposition method and a sputtering method
can be adopted to stack the metal electrode 5. Of these methods,
the vapor deposition method is preferably employed from the
viewpoint of maintaining the concavity and convexity structure
formed on the surface of the resin 80. Accordingly, an organic EL
element 200 having a structure as shown in FIG. 4 can be
obtained.
[0158] In the method for producing the organic EL element of the
present invention, the resin 80 on the base member 10 has the
chevron-shaped structure. Thus, each of the transparent electrode
3, the organic layer 4, and the metal electrode 5 is readily
stacked to maintain the chevron-shaped structure of the resin 80.
Hence, it is possible to sufficiently suppress repetition of
multiple reflection of light generated in the organic layer 4 in
the element due to total reflection at each interface. Further, it
is also possible to re-emit light which has been totally reflected
at an interface between the transparent supporting substrate and
the air by diffraction effect. Furthermore, since each of the
transparent electrode 3, the organic layer 4, and the metal
electrode 5 is more likely to have the same structure as the
chevron-shaped structure formed on the surface of the resin layer
80, an inter-electrode distance between the transparent electrode 3
and the metal electrode 5 is partially short. For this reason, in
comparison with those in which the inter-electrode distance between
the transparent electrode 3 and the metal electrode 5 is uniform,
an increase in electric field intensity can be expected in
application of voltage, and also light emission efficiency of the
organic EL element can be improved.
[0159] In the diffraction grating produced according to the present
invention and the organic EL element including the diffraction
grating, the average height of the concavities and convexities
formed on the surface (the cured surface of curable resin) of the
diffraction grating is preferably within the range from 5 to 200
nm, more preferably within the range from 20 to 200 nm, and further
preferably within the range from 50 to 150 nm as described
above.
[0160] In the diffraction grating produced according to the present
invention and the organic EL element including the diffraction
grating, the average pitch of the concavities and convexities
forming on the surface (the cured surface of curable resin) of the
diffraction grating is preferably within the range from 100 to 600
nm, and more preferably within the range from 200 to 600 nm as
described above.
[0161] In the diffraction grating produced according to the present
invention and the organic EL element including the diffraction
grating, according to the inventors' knowledge and perceptions, for
the cross-section shape of the concavity and convexity structure
formed on the surface (the cured surface of curable resin) of the
diffraction grating, an average value m and a median M of a depth
distribution of the concavities and convexities on the
cross-section obtained by a method which will be described later
preferably satisfy the following expression:
(1.062m-2.2533).times.0.95.ltoreq.M.ltoreq.(1.062m-2.2533).times.1.05
In a case that the median (M) and the average value (m) satisfy the
above expression, it is considered that generation of leakage
current can be suppressed sufficiently when the diffraction grating
is used for the organic EL element etc.
[0162] In the diffraction grating produced according to the present
invention and the organic EL element including the diffraction
grating, a kurtosis of the cross-section shape of the concavity and
convexity structure formed on the surface (the surface of cured
curable resin) of the diffraction grating is preferably -1.2 or
more, and more preferably -1.2 to 1.2. In a case that the kurtosis
is less than the lower limit, the leakage current is more likely to
be generated when the diffraction grating is used for the organic
EL element. In a case that the kurtosis exceeds the upper limit,
the concavities and convexities on the surface (resin layer) of the
diffraction grating are decreased. As a result, it is considered to
cause the following situation. That is, not only the diffraction
effect cannot be obtained sufficiently, but also the electric field
is more likely to be concentrated on the portions of the
projections, so that leakage currents are more likely to be
generated. The kurtosis and a method for measuring the kurtosis
will be described later on.
EXAMPLES
[0163] Hereinafter, the present invention will be described in
detail by Examples and Comparative Examples. However, the present
invention is not limited to Examples below.
[0164] At first, an explanation will be made about five block
copolymers used in Examples and Comparative examples described
below. Regarding any of five block copolymers, polystyrene
(hereinafter referred to as "PS" in an abbreviated manner as
appropriate) was used as the first polymer segment, and polymethyl
methacrylate (hereinafter referred to as "PMMA" in an abbreviated
manner as appropriate) was used as the second polymer segment. The
volume ratio of the first polymer segment and second polymer
segment (the first polymer segment: the second polymer segment) in
each block copolymer was calculated on the assumption that the
density of polystyrene was 1.05 g/cm.sup.3, the density of
polymethyl methacrylate was 1.19 g/cm.sup.3. The number average
molecular weights (Mn) and the weight average molecular weights
(Mw) of polymer segments or polymers were measured by using gel
permeation chromatography (Model No: "GPC-8020" manufactured by
Tosoh Corporation, in which TSK-GEL SuperH1000, SuperH2000,
SuperH3000, and SuperH4000 were connected in series). The glass
transition temperatures (Tg) of polymer segments were measured by
use of a differential scanning calorimeter (manufactured by
Perkin-Elmer under the product name of "DSC7"), while the
temperature was raised at a rate of temperature rise of 20 degrees
Celsius/min over a temperature range from 0 to 200 degrees Celsius.
The solubility parameters of polystyrene and polymethyl
methacrylate were 9.0 and 9.3, respectively (see Kagaku Binran
Ouyou Hen (Handbook of Chemistry, Applied Chemistry), 2nd
edition).
Block copolymer 1 (hereinafter referred to as "BCP-1" in an
abbreviated manner as appropriate) A block copolymer of PS and PMMA
(manufactured by Polymer Source Inc.) Mn of PS segment=868,000 Mn
of PMMA segment=857,000 Mn of block copolymer=1,725,000 Volume
ratio between PS segment and PMMA segment (PS:PMMA)=53:47 Molecular
weight distribution (Mw/Mn)=1.30 Tg of PS segment=96 degrees
Celsius Tg of PMMA segment=110 degrees Celsius Block copolymer 2
(hereinafter referred to as "BCP-2" in an abbreviated manner as
appropriate) A block copolymer of PS and PMMA (manufactured by
Polymer Source Inc.) Mn of PS segment=750,000 Mn of PMMA
segment=720,000 Mn of block copolymer=1,470,000 Volume ratio
between PS segment and PMMA segment (PS:PMMA)=54:46 Molecular
weight distribution (Mw/Mn)=1.21 Tg of PS segment=107 degrees
Celsius Tg of PMMA segment=134 degrees Celsius Block copolymer 3
(hereinafter referred to as "BCP-3" in an abbreviated manner as
appropriate) A block copolymer of PS and PMMA (manufactured by
Polymer Source Inc.) Mn of PS segment=500,000, Mn of PMMA
segment=480,000 Mn of block copolymer=980,000 Volume ratio between
PS segment and PMMA segment (PS:PMMA)=54:46 Molecular weight
distribution (Mw/Mn)=1.18 Tg of PS segment=107 degrees Celsius Tg
of PMMA segment=134 degrees Celsius Block copolymer 4 (hereinafter
referred to as "BCP-4" in an abbreviated manner as appropriate) A
block copolymer of PS and PMMA (manufactured by Polymer Source
Inc.) Mn of PS segment=270,000 Mn of PMMA segment=289,000 Mn of
block copolymer=559,000 Volume ratio between PS segment and PMMA
segment (PS:PMMA)=51:49 Molecular weight distribution (Mw/Mn)=1.18
Tg of PS segment=110 degrees Celsius Tg of PMMA segment=124 degrees
Celsius Block copolymer 5 (hereinafter referred to as "BCP-5" in an
abbreviated manner as appropriate) A block copolymer of PS and PMMA
(manufactured by Polymer Source Inc.) Mn of PS segment=133,000 Mn
of PMMA segment=130,000 Mn of block copolymer=263,000 Volume ratio
between PS segment and PMMA segment (PS:PMMA)=54:46 Molecular
weight distribution (Mw/Mn)=1.15 Tg of PS segment=110 degrees
Celsius Tg of PMMA segment=124 degrees Celsius
Example 1
[0165] Toluene was added to 150 mg of the block copolymer 1 and 38
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. (Mw=3000, Mw/Mn=1.10) as polyethylene oxide so
that the total amount thereof was 10 g, followed by dissolving
them. Then, the solution was filtrated or filtered through a
membrane filter having a pore diameter of 0.5 .mu.m to obtain a
block copolymer solution. The obtained block copolymer solution was
applied, on a polyphenylene sulfide film (TORELINA manufactured by
TORAY INDUSTRIES, INC.) as a base member, in a film thickness of
200 to 250 nm, by a spin coating. The spin coating was performed at
a spin speed of 500 rpm for 10 seconds, and then performed at a
spin speed of 800 rpm for 30 seconds. The thin film applied by the
spin coating was left at a room temperature for 10 minutes until
the thin film was dried.
[0166] Subsequently, the base member on which the thin film was
formed was heated for 5 hours in an oven of 170 degrees Celsius
(first annealing process). Concavities and convexities were
observed on the surface of the heated thin film, and it was found
out that micro phase separation of the block copolymer forming the
thin film was caused. The cross-section of the thin film was
observed with a transmission electron microscope (TEM) (H-7100FA
manufactured by Hitachi, Ltd.). As shown in the micrograph, of FIG.
5A, obtained by the transmission electron microscope, as a result
of RuO4 staining, PS portions look black and PMMA portions look
white.
[0167] The heated thin film as described above was subjected to an
etching process as described below to selectively decompose and
remove PMMA on the base member. The thin film was irradiated with
ultraviolet rays at an irradiation intensity of 30 J/cm.sup.2 by
use of a high pressure mercury lamp. Then, the thin film was
immersed in acetic acid, and was subjected to cleaning with
ion-exchanged water, followed by being dried. As a result, there
was formed, on the base member, a concavity and convexity pattern
clearly deeper than the concavities and convexities which appeared
on the surface of the thin film by the heating process.
[0168] Next, the base member was subjected to a heating process
(second annealing process) for 1 hour in an oven of 140 degrees
Celsius so that the concavity and convexity pattern formed by the
etching process was deformed to have a chevron-shaped structure
(process for forming a shape of chevrons).
[0169] About 10 nm of a thin nickel layer was formed as a current
seed layer by a sputtering on the surface of the thin film, for
which the process for forming the shape of chevrons had been
performed. Subsequently, the base member with the thin film was
subjected to an electroforming process (maximum current density:
0.05 A/cm.sup.2) in a nickel sulfamate bath at a temperature of 50
degrees Celsius to precipitate nickel until the thickness of nickel
became 250 .mu.m. The base member Chemisol with the thin film was
mechanically peeled off from the nickel electroforming body
obtained as described above. Subsequently, the nickel
electroforming body was immersed in Chemisol 2303 manufactured by
The Japan Cee-Bee Chemical Co., Ltd., followed by being cleaned
while being stirred for 2 hours at 50 degrees Celsius. Thereafter,
polymer component(s) adhered to a part of the surface of the
electroforming body was(were) removed by repeating the following
process three times. That is, an acrylic-based UV curable resin was
applied on the nickel electroforming body; and the applied
acrylic-based UV curable resin was cured; and then the cured resin
was peeled off.
[0170] The cross-section of the nickel electroforming body from
which the polymer component was removed was observed with a
scanning electron microscope (FE-SEM: S4800 manufactured by
Hitachi, Ltd.). The observation is shown in FIG. 5B (magnifying
magnification: 100-thousand times). It was understood from FIG. 5B
that concavities and convexities of the nickel electroforming body
were smooth and the cross-section of each convex portion had a
smooth chevron shape having no overhang.
[0171] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which mold-release treatment had
been performed was obtained.
[0172] Subsequently, a fluorine-based UV curable resin was applied
on a PET substrate (COSMOSHINE A-4100 manufactured by Toyobo Co.,
Ltd.). Then, the fluorine-based UV curable resin was cured by
irradiation with ultraviolet rays at 600 mJ/cm.sup.2, with the
obtained nickel mold being pressed thereto. After curing of the
resin, the nickel mold was peeled off from the cured resin.
Accordingly, a diffraction grating made of the PET substrate with
the resin film to which the surface profile of the nickel mold was
transferred was obtained.
[0173] An analysis image of the concavity and convexity shape on
the surface of the resin in the diffraction grating was obtained by
using an atomic force microscope (a scanning probe microscope
equipped with an environment control unit "Nanonavi II
Station/E-sweep" manufactured by SII NanoTechnology Inc.). Analysis
conditions of the atomic force microscope were as follows.
Measurement mode: dynamic force mode
Cantilever: SI-DF40 (material: Si, lever width: 40 diameter of tip
of chip: 10 nm) Measurement atmosphere: in air Measurement
temperature: 25 degrees Celsius
[0174] FIG. 5E shows a concavity and convexity analysis image of
the surface of the resin of the obtained diffraction grating. For
comparison, FIG. 5C shows a concavity and convexity analysis image
of the concavity and convexity pattern of the block copolymer from
which PMMA was selectively removed by the etching process, and FIG.
5D shows a concavity and convexity analysis image of the concavity
and convexity pattern of the mold formed by the electroforming. The
pattern shown in FIG. 5D was a pattern transferred from the pattern
shown in FIG. 5C, and thus the pattern shown in FIG. 5D was the
inverted pattern of the pattern shown in FIG. 5C. It was found out
that patterns of FIGS. 5C, 5D, and 5E had a common pattern
regularity and/or common pattern pitch, and that the concavity and
convexity pattern of the block copolymer from which PMMA was
selectively removed by the etching process was satisfactorily
reflected by the electroforming and the transfer to the resin to be
thereafter performed.
[0175] FIG. 5F shows a concavity and convexity analysis image of
the cross-section in the vicinity of the surface of the resin of
the obtained diffraction grating. From the concavity and convexity
analysis images of the diffraction grating as shown in FIGS. 5E and
5F, Each of an average height of the concavities and convexities,
an average pitch of the concavities and convexities, a
Fourier-transformed image, an average value and a median of a depth
distribution of the concavities and convexities, and a kurtosis of
the concavities and convexities was obtained by the following
methods.
<Average Height of Concavities and Convexities>
[0176] A concavity and convexity analysis image was obtained as
described above by performing a measurement in a randomly selected
measuring region of 3 .mu.m square (length: 3 .mu.m, width: 3
.mu.m) in the diffraction grating. Distances between randomly
selected concave portions and convex portions in the depth
direction were measured at 100 points or more in the concavity and
convexity analysis image, and the average of the distances was
calculated as the average height (depth) of the concavities and
convexities. The average height of the concavity and convexity
pattern in the analysis image obtained in this example was 62
nm.
<Average Pitch of Concavities and Convexities>
[0177] A concavity and convexity analysis image was obtained as
described above by performing a measurement in a randomly selected
measuring region of 3 .mu.m square (length: 3 .mu.m, width: 3
.mu.m) in the diffraction grating. Distances between randomly
selected adjacent convex portions or between randomly selected
adjacent concave portions were measured at 100 points or more in
the concavity and convexity analysis image, and the average of the
distances was calculated as the average pitch of the concavities
and convexities. The average pitch of the concavity and convexity
pattern in the analysis image obtained in this example was 480
nm.
<Fourier-Transformed Image>
[0178] A concavity and convexity analysis image was obtained as
described above by performing a measurement in a randomly selected
measuring region of 3 .mu.m square (length: 3 .mu.m, width: 3
.mu.m) in the diffraction grating. The obtained concavity and
convexity analysis image was subjected to a flattening process
including primary inclination correction, and then to
two-dimensional fast Fourier transform processing. Thus, a
Fourier-transformed image was obtained. FIG. 5G shows the obtained
Fourier-transformed image. As is clear from the result shown in
FIG. 5G, it was confirmed that the Fourier-transformed image showed
a circular pattern substantially centered at an origin at which an
absolute value of wavenumber was 0 .mu.m.sup.-, and that the
circular pattern was present within a region where the absolute
value of wavenumber was within a range of 10 .mu.m.sup.-1 or
less.
[0179] The circular pattern of the Fourier-transformed image is a
pattern observed due to gathering of bright spots in the
Fourier-transformed image. The term "circular" herein means that
the pattern of the gathering of the bright spots looks like a
substantially circular shape, and is a concept further including a
case where a part of a contour looks like a convex shape or a
concave shape. The gathering of the bright spots may look like a
substantially annular shape, and this case is expressed as the term
"annular". It is noted that the term "annular" is a concept further
including a case where a shape of an outer circle or inner circle
of the ring looks like a substantially circular shape and further
including a case where a part of the contours of the outer circle
and/or the inner circle of the ring looks like a convex shape or a
concave shape. Further, the phrase "the circular or annular pattern
is present within a region where an absolute value of wavenumber is
within a range of 10 .mu.m.sup.-1 or less (more preferably from
1.25 to 10 .mu.m.sup.-1, further preferably from 1.25 to 5
.mu.m.sup.-1)" means that 30% or more (more preferably 50% or more,
further more preferably 80% or more, and particularly preferably
90% or more) of bright spots forming the Fourier-transformed image
are present within a region where the absolute value of wavenumber
is within a range of 10 .mu.m.sup.-1 or less (more preferably from
1.25 to 10 .mu.m.sup.-1, and further preferably from 1.25 to 5
.mu.m.sup.-1).
[0180] The two-dimensional fast Fourier transform processing on the
concavity and convexity analysis image can be easily performed by
electronic image processing using a computer equipped with software
for two-dimensional fast Fourier transform processing.
<Average Value and Median of Depth Distribution of Concavities
and Convexities>
[0181] A concavity and convexity analysis image was obtained by
performing a measurement in a randomly selected measuring region of
3 .mu.m square (length: 3 .mu.m, width: 3 .mu.m) in the diffraction
grating. Here, data of each of the heights of the concavities and
convexities was determined at 16384 (128 columns.times.128 rows) or
more measuring points in the measuring region on the nanometer
scale. By using E-sweep in this example, a measurement at 65536
points (256 columns.times.256 rows) (a measurement with a
resolution of 256 pixels.times.256 pixels) was conducted in a
measuring region of 3 .mu.m square. Regarding the thus measured
heights (unit: nm) of the concavities and convexities, first, a
measuring point P which had the largest height from the surface of
the substrate among all the measuring points was determined. Then,
while a plane which included the measuring point P and was parallel
to the surface of the substrate was taken as a reference plane
(horizontal plane), values of depths from the reference plane (the
differences each obtained by subtracting the height from the
substrate at one of the measuring points from the value of the
height from the substrate at the measuring point P) were determined
as concavity and convexity depth data. The concavity and convexity
depth data could be determined by automatic calculation with
software provided in E-sweep. The values determined by automatic
calculation could be used as the concavity and convexity depth
data. After the concavity and convexity depth data was determined
at each measuring point as described above, the average value (m)
of the depth distribution of the concavities and convexities could
be determined by calculation according to the following formula
(I):
m = 1 N i = 1 N x i ( I ) ##EQU00001##
[0182] In the formula (I), N represents a total number of measuring
points (the number of all the pixels), i represents any integer of
1 to N, x.sub.i represents the concavity and convexity depth data
at the i-th measuring point, and m represents the average value of
the depth distribution of the concavities and convexities. Further,
the median (M) of the depth distribution of the concavities and
convexities could be determined as follows. The concavity and
convexity depth data x.sub.i at all the 1 to N-th measuring points
were rearranged in ascending order, and expressed as x.sub.(i) (in
this case, the order of the heights was as follows:
x.sub.(1)<x.sub.(2)<x.sub.(3)< . . . <x.sub.(N)). Then,
the median (M) could be determined by calculation according to one
of the following formulae (II) depending on whether N was an odd
number or an even number:
( In a case where N was odd number ) M = x ( ( N + 1 ) / 2 ) ( In a
case where N was even number ) M = x ( N / 2 ) + x ( ( N / 2 ) + 1
) 2 } ( II ) ##EQU00002##
[0183] In the formulae (II), N represents the total number of
measuring points (the number of all the pixels), and M represents
the median of the depth distribution of the concavities and
convexities. The average value (m) of the depth distribution of the
concavities and convexities in the diffraction grating obtained in
this example was 52.21 nm and the median (M) of the depth
distribution of the concavities and convexities was 57.00 nm.
<Kurtosis of Concavities and Convexities>
[0184] Similar to the method for measuring the median (M) of the
depth distribution and the average value (m) of the depth
distribution, data of each of the heights of the concavities and
convexities was determined at 16384 (128 columns.times.128 rows) or
more measuring points in the measuring region of 3 .mu.m square. In
this example, a measurement was performed adopting 65536 measuring
points (256 columns.times.256 rows). Thereafter, the average value
(m) of the depth distribution of the concavities and convexities
and the standard deviation (.sigma.) of the depth distribution of
the concavities and convexities were calculated on the basis of the
concavity and convexity depth data of the measuring points. Note
that, the average value (m) could be determined by calculation
according to the above-described formula (I) as described above.
Meanwhile, the standard deviation (.sigma.) of the depth
distribution could be determined by calculation according to the
following formula (III):
.sigma. = 1 N i = 1 N ( x i - m ) 2 ( III ) ##EQU00003##
[0185] In the formula (III), N represents a total number of
measuring points (the number of all the pixels), x.sub.i represents
the concavity and convexity depth data at the i-th measuring point,
and m represents the average value of the depth distribution of the
concavities and convexities. Subsequently, on the basis of the thus
determined values of the average value (m) and the standard
deviation (.sigma.), the kurtosis (k) could be determined by
calculation according to the following formula (IV):
k = 1 N i = 1 N ( x i - m ) 4 .sigma. 4 - 3 ( IV ) ##EQU00004##
[0186] In formula (IV), N represents the total number of measuring
points (the number of all the pixels), x.sub.i represents the
concavity and convexity depth data at the i-th measuring point, m
represents the average value of the depth distribution of the
concavities and convexities, and a represents a value of the
standard deviation. The Kurtosis of concavities and convexities in
the diffraction grating obtained in this example was -0.546.
<Manufacture of Organic EL Element>
[0187] On the UV curable resin film as the diffraction grating
obtained as described above, a transparent electrode (ITO,
thickness: 120 nm), a hole transporting layer
(N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine,
thickness: 40 nm), an electron transporting layer
(8-hydroxyquinoline aluminum, thickness: 30 nm), a lithium fluoride
layer (thickness: 1.5 nm), and a metal electrode (aluminum,
thickness: 100 nm) were each stacked by a vapor deposition method
to maintain the shape of the concavities and convexities formed on
the surface of the cured resin layer. Accordingly, the organic EL
element having a structure as shown in FIG. 4 was obtained.
Example 2
[0188] Toluene was added to 120 mg of the block copolymer 2 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution.
[0189] Subsequently, 0.7 g of octadecyldimethylchlorosilane (ODS)
was added to 500 ml of heptane, followed by being stirred to
prepare 2.0 mM of ODS solution. A glass substrate after cleaning
having a thickness of 1.1 mm was immersed in the solution and
stationarily placed for 24 hours. This processed substrate was
subjected to ultrasonic cleaning with chloroform for 10 minutes and
then subjected to ultrasonic cleaning with pure water for 10
minutes, followed by being dried. Accordingly, an ODS-processed
glass substrate was obtained.
[0190] The obtained block copolymer solution was applied, on the
ODS-processed glass substrate, in a film thickness of 200 to 250
nm, by a spin coating to form a thin film. The spin coating was
performed at a spin speed of 500 rpm for 10 seconds, and then
performed at a spin speed of 800 rpm for 30 seconds. After the spin
coating, the thin film was left at a room temperature for 10
minutes until the thin film was dried.
[0191] Subsequently, the substrate was heated for 3 hours in an
oven of 160 degrees Celsius (first annealing process). It was
observed that concavities and convexities were formed on the thin
film on the surface of the heated base member and that micro phase
separation of the block copolymer was caused.
[0192] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetone,
and was subjected to cleaning with ion-exchanged water, followed by
being dried. By performing the etching process, PMMA on the
substrate was selectively removed to obtain a thin film with a
minute concavity and convexity pattern.
[0193] The base member was subjected to a heating process (second
annealing process) for 3 hours in an oven of 125 degrees Celsius so
that the thin film was subjected to a process for forming a shape
of chevrons.
[0194] Subsequently, about 10 nm of a thin nickel layer was formed
on the surface of the thin film by a sputtering. Then, the base
member was subjected to an electroforming process under the same
condition as Example 1 in a nickel sulfamate bath to precipitate
nickel until the thickness of nickel became 250 .mu.m. The base
member on which the nickel was deposited as described above was
mechanically peeled off from the nickel electroforming body. The
nickel electroforming body from which the base member was peeled
off was immersed in Chemisol 2303 manufactured by The Japan Cee-Bee
Chemical Co., Ltd., followed by being cleaned while being stirred
for 2 hours at 50 degrees Celsius. Thereafter, the nickel
electroforming body was immersed in a tetrahydrofuran solution and
an ultrasonic cleaning process was carried out for 30 minutes.
Polymer component(s), adhered to a part of the surface of the
electroforming body, which was(were) visually confirmed was(were)
removed.
[0195] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained.
[0196] Subsequently, a fluorine-based UV curable resin was applied
on a PET substrate (COSMOSHINE A-4100 manufactured by Toyobo Co.,
Ltd.). After the nickel mold was pressed against the fluorine-based
UV curable resin, the fluorine-based UV curable resin was cured by
irradiation with ultraviolet rays at 600 mJ/cm.sup.2 and then the
nickel mold was peeled off. Accordingly, a UV curable resin film to
which the surface profile of the nickel mold was transferred was
obtained. Again, the fluorine-based UV curable resin was applied on
a PET substrate (COSMOSHINE A-4100 manufactured by Toyobo Co.,
Ltd.). After the UV curable resin film was pressed against the
fluorine-based UV curable resin, the fluorine-based UV curable
resin was cured by irradiation with ultraviolet rays at 600
mJ/cm.sup.2 and then the UV curable resin film was peeled off.
Accordingly, a second UV curable resin film was obtained. Further,
the fluorine-based UV curable resin was applied on a glass for
which a silane coupling process had been performed. After the
second UV curable resin film was pressed against the fluorine-based
UV curable resin, the fluorine-based UV curable resin was cured by
irradiation with ultraviolet rays at 600 mJ/cm.sup.2 and then the
second UV curable resin film was peeled off. Accordingly, a
diffraction grating in which a pattern was formed on the glass
substrate was obtained. For the concavity and convexity pattern of
the diffraction grating, the concavity and convexity shape on the
surface was analyzed by using the atomic force microscope in the
same manner as Example 1 to obtain an analysis image. Analysis
conditions of the atomic force microscope were the same as those in
Example 1.
[0197] FIG. 6D shows the obtained concavity and convexity analysis
image. For comparison, FIG. 6A shows a concavity and convexity
analysis image of the concavity and convexity pattern of the block
copolymer from which PMMA was selectively removed by the etching
process; FIG. 6B shows a concavity and convexity analysis image of
the concavity and convexity pattern for which the process for
forming the shape of chevrons was performed in the second anneal
step after the etching process; and FIG. 6C shows a concavity and
convexity analysis image of the concavity and convexity pattern of
the mold formed by the electroforming. The pattern shown in FIG. 6C
was the inverted pattern of those shown in FIGS. 6A, 6B, and 6D. It
was found out that patterns of FIGS. 6A, 6B, 6C, and 6D had a
common pattern regularity and/or common pattern pitch, and that the
planar shape of the concavity and convexity pattern of the block
copolymer from which PMMA was selectively removed by the etching
process was satisfactorily reflected by the second heating, the
electroforming, and the transfer to the resin to be thereafter
performed.
[0198] FIG. 6E shows a concavity and convexity analysis image of
the cross-section in the vicinity of the surface of the obtained
diffraction grating. From the analysis images (FIGS. 6D and 6E) of
the surfaces of the diffraction grating, an average height of the
concavities and convexities, an average pitch of the concavities
and convexities, an average value (m) and a median (M) of a depth
distribution of the concavities and convexities, and a kurtosis of
the concavities and convexities of the diffraction grating were
each obtained in the same manner as Example 1. The results thereof
are described as follows.
Average height: 55 nm Average pitch: 320 nm Average value (m) of
depth distribution: 44.93 nm Median (M) of depth distribution: 45.7
nm
Kurtosis: -1.13
[0199] FIG. 6F shows a Fourier-transformed image obtained from the
analysis images. As is apparent from the result shown in FIG. 6F,
it was observed that the Fourier-transformed image showed a
circular pattern substantially centered at an origin at which an
absolute value of wavenumber was 0 .mu.m.sup.-1, and that the
circular pattern was present within a region where the absolute
value of wavenumber was within a range of 10 .mu.m.sup.-1 or
less.
<Manufacture of Organic EL Element>
[0200] On the glass substrate with the pattern made of the
fluorine-based UV curable resin as the diffraction grating obtained
as described above, a transparent electrode (ITO, thickness: 120
nm), a hole transporting layer
(N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine,
thickness: 40 nm), an electron transporting layer
(8-hydroxyquinoline aluminum, thickness: 30 nm), a lithium fluoride
layer (thickness: 1.5 nm), and a metal electrode (aluminum,
thickness: 100 nm) were each stacked by a vapor deposition method
to maintain the shape of the concavities and convexities formed on
the surface of the cured resin layer. Accordingly, the organic EL
element was obtained.
<Evaluation of Light Emission Efficiency of Organic EL
Element>
[0201] A light emission efficiency of the organic EL element
obtained in this example was measured by the following method. That
is, voltage was applied to the obtained organic EL element, and
then the applied voltage V and current I flowing through the
organic EL element were measured with a source measurement
instrument (manufactured by ADC CORPORATION, R6244), and a total
luminous flux amount L was measured with a total flux measurement
apparatus manufactured by Spectra Co-op. From the thus obtained
measured value of the applied voltage V, the current I, and the
total luminous flux amount L, a luminance value L' was calculated.
Here, for the current efficiency, the following calculation formula
(F1) was used:
Current efficiency=(L'/I).times.S (F1)
and, for the power efficiency, the following calculation formula
(F2) was used:
Power efficiency=(L'/I/V).times.S (F2)
Accordingly, the current efficiency and the power efficiency of the
organic EL element were calculated. In the above formulae, S is a
light-emitting or luminescent area of the organic EL element. FIG.
6G shows a graph showing change of the current efficiency of the
organic EL element obtained by using the above formula with respect
to the luminance L'. Further, FIG. 6H shows a graph showing change
of the power efficiency of the organic EL element calculated by
using the above formula with respect to the luminance L'. In each
of FIG. 6G and FIG. 6H, square marks indicate results of this
example and circular dots indicate results of the organic EL
element produced by stacking each layer on a glass substrate in
which no concavity and convexity pattern of the diffraction grating
is formed, in the same manner as described above. Noted that the
value of the luminance L' was calculated on the assumption that
light distribution characteristic of the organic EL element
followed Lambert's law. The following calculation formula (F3) was
used:
L'=L/.pi./S (F3)
[0202] From the result shown in FIG. 6G, it was found that the
current efficiency of the organic EL element of this example at a
luminance of 500 to 2000 cd/m.sup.2 was about 2.5 times that of the
organic EL element having no concavity and convexity on the glass
substrate. Further, from the result shown in FIG. 6H, it was found
that the current efficiency of the organic EL element of this
example at the luminance of 500 to 2000 cd/m.sup.2 was about 3
times that of the organic EL element having no concavity and
convexity on the glass substrate. Therefore, the organic EL element
of the present invention had an external extraction efficiency
sufficiently.
<Evaluation of Light Emission Directivity of Organic EL
Element>
[0203] The directivity of light emission of the organic EL element
obtained in this example was evaluated by the following method.
That is, the organic EL element in a luminescent state was visually
observed in all the directions (directions of all around
360.degree.). Neither particularly bright sites nor particularly
dark sites were observed when the organic EL element obtained in
Example 2 was observed in any of the directions of all around
360.degree., and the brightness was uniform in all the directions.
In this way, it was shown that the directivity of light emission of
the organic EL element of the present invention was sufficiently
low.
Example 3
[0204] Toluene was added to 120 mg of the block copolymer 2 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution.
[0205] Subsequently, 170 mg of methyltrimethoxysilane (MTMS) and 89
mg of 1,2-bis(trimethoxysilyl)ethane (BTMSE) were added to 4.75 g
of methylisobutylketone, followed by being stirred to prepare
methyltrimethoxysilane/1,2-bis(trimethoxysilyl)ethane solution.
This solution was applied on a glass substrate after cleaning
having a thickness of 1.1 mm by a spin coating to obtain a glass
substrate with a coating film made of
methyltrimethoxysilane/1,2-bis(trimethoxysilyl)ethane. The spin
coating was performed at a spin speed of 500 rpm for 10 seconds,
and then performed at a spin speed of 800 rpm for 30 seconds. The
glass substrate with the coating film was sintered for 6 hours in a
nitrogen atmosphere at a temperature of 280 degrees Celsius to
obtain an organo silicate processed glass substrate.
[0206] The obtained block copolymer solution was applied, on the
organo silicate processed glass substrate, in a film thickness of
200 to 250 nm, by a spin coating, to form a thin film. The spin
coating was performed at a spin speed of 500 rpm for 10 seconds,
and then performed at a spin speed of 800 rpm for 30 seconds. After
the spin coating, the thin film was left at a room temperature for
10 minutes until the thin film was dried.
[0207] Subsequently, the base member was heated for 6 hours in an
oven of 160 degrees Celsius (first annealing process). It was
observed that concavities and convexities were formed on the thin
film on the surface of the heated base member and that micro phase
separation of the block copolymer was caused.
[0208] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetone,
and was subjected to cleaning with ion-exchanged water, followed by
being dried. By performing the etching process, PMMA on the
substrate was selectively removed to obtain a thin film with a
minute concavity and convexity pattern.
[0209] The base member was subjected to a heating process (second
annealing process) for 1 hour in an oven of 125 degrees Celsius so
that the thin film was subjected to a process for forming a shape
of chevrons.
[0210] Subsequently, about 10 nm of a thin nickel layer was formed
on the surface of the thin film by a sputtering. Then, the base
member was subjected to an electroforming process under the same
condition as Example 1 in a nickel sulfamate bath to precipitate
nickel until the thickness of nickel became 250 .mu.m. The base
member on which the nickel was deposited as described above was
immersed in a tetrahydrofuran solution, and then the base member
was peeled off from the nickel electroforming body. The nickel
electroforming body from which the base member was peeled off was
immersed in the tetrahydrofuran solution and an ultrasonic cleaning
process was carried out for 30 minutes. Polymer component(s),
adhered to a part of the surface of the electroforming body, which
was(were) visually confirmed was(were) removed.
[0211] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained. Subsequently, a fluorine-based UV
curable resin was applied on a PET substrate (COSMOSHINE A-4100
manufactured by Toyobo Co., Ltd.). After the nickel mold was
pressed against the fluorine-based UV curable resin, the
fluorine-based UV curable resin was cured by irradiation with
ultraviolet rays at 600 mJ/cm.sup.2 and then the nickel mold was
peeled off. Accordingly, a UV curable resin film to which the
surface profile of the nickel mold was transferred was obtained.
Further, the fluorine-based UV curable resin was applied on a glass
for which a silane coupling process had been performed. After the
UV curable resin film was pressed against the fluorine-based UV
curable resin, the fluorine-based UV curable resin was cured by
irradiation with ultraviolet rays at 600 mJ/cm.sup.2 and then the
UV curable resin film was peeled off. Accordingly, a diffraction
grating formed of the glass substrate was obtained. For the
concavity and convexity pattern of the diffraction grating, the
concavity and convexity shape on the surface was analyzed by using
the atomic force microscope used in Example 1 to obtain an analysis
image. Analysis conditions of the atomic force microscope were the
same as those in Example 1.
[0212] FIG. 7C shows the obtained concavity and convexity analysis
image. For comparison, FIG. 7A shows a concavity and convexity
analysis image of the concavity and convexity pattern of the block
copolymer from which PMMA was selectively removed by the etching
process; and FIG. 7B shows a concavity and convexity analysis image
of the concavity and convexity pattern for which the process for
forming the shape of chevrons was performed in the second anneal
step after the etching process. It was found out that the patterns
shown in FIGS. 7A, 7B, and 7C had a common pattern regularity
and/or common pattern pitch and that the planar shape of the
concavity and convexity pattern of the block copolymer from which
PMMA was selectively removed by the etching process was
satisfactorily reflected by the second heating process and the
transfer of the mold to the resin.
[0213] FIG. 7D shows a concavity and convexity analysis image of
the cross-section in the vicinity of the surface of the obtained
diffraction grating. From the analysis images of the surfaces of
the diffraction grating, an average height of the concavities and
convexities, an average pitch of the concavities and convexities,
an average value (m) and a median (M) of a depth distribution of
the concavities and convexities, and a kurtosis of the concavities
and convexities of the diffraction grating were each obtained in
the same manner as Example 1. The results thereof are described as
follows.
Average height: 61 nm Average pitch: 310 nm Average value (m) of
depth distribution: 48.69 nm Median (M) of depth distribution:
50.41 nm
Kurtosis: -1.17
[0214] FIG. 7E shows a Fourier-transformed image obtained from the
analysis images. As is apparent from the result shown in FIG. 7E,
it was observed that the Fourier-transformed image showed a
circular pattern substantially centered at an origin at which an
absolute value of wavenumber was 0 .mu.m.sup.-1, and that the
circular pattern was present within a region where the absolute
value of wavenumber was within a range of 10 .mu.m.sup.-1 or
less.
[0215] On the glass substrate with the concavities and convexities
as the diffraction grating obtained as described above, a
transparent electrode (ITO, thickness: 120 nm), a hole transporting
layer
(N,N'-diphenyl-N,N-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine,
thickness: 40 nm), an electron transporting layer
(8-hydroxyquinoline aluminum, thickness: 30 nm), a lithium fluoride
layer (thickness: 1.5 nm), and a metal electrode (aluminum,
thickness: 100 nm) were each stacked by a vapor deposition method
to maintain the shape of the concavities and convexities formed on
the surface of the cured resin layer. Accordingly, the organic EL
element was obtained.
Example 4
[0216] Toluene was added to 120 mg of the block copolymer 3 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution.
[0217] 170 mg of methyltrimethoxysilane (MTMS) and 89 mg of
1,2-bis(trimethoxysilyl)ethane (BTMSE) were added to 4.75 g of
methylisobutylketone, followed by being stirred to prepare
methyltrimethoxysilane/1,2-bis(trimethoxysilyl)ethane solution.
This solution was applied on a glass substrate after cleaning
having a thickness of 1.1 mm by a spin coating to obtain a glass
substrate with a coating film made of
methyltrimethoxysilane/1,2-bis(trimethoxysilyl)ethane. The spin
coating was performed at a spin speed of 500 rpm for 10 seconds,
and then performed at a spin speed of 800 rpm for 30 seconds.
Subsequently, the glass substrate with the coating film was
sintered for 6 hours in a nitrogen atmosphere at a temperature of
300 degrees Celsius to obtain an organo silicate processed glass
substrate.
[0218] The obtained block copolymer solution was applied, on the
organo silicate processed glass substrate, in a film thickness of
200 to 250 nm, by a spin coating. The spin coating was performed at
a spin speed of 500 rpm for 10 seconds, and then performed at a
spin speed of 800 rpm for 30 seconds. After the spin coating, the
thin film was left at a room temperature for 10 minutes until the
thin film was dried.
[0219] Subsequently, the substrate was heated for 6 hours in an
oven of 160 degrees Celsius (first annealing process). It was
observed that concavities and convexities were formed on the thin
film on the surface of the heated base member and that micro phase
separation of the block copolymer was caused.
[0220] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetone,
and was subjected to cleaning with ion-exchanged water, followed by
being dried. By performing the etching process, PMMA on the
substrate was selectively removed to obtain a thin film with a
minute concavity and convexity pattern.
[0221] The base member was subjected to a heating process (second
annealing process) for 1 hour in an oven of 125 degrees Celsius so
that the thin film was subjected to a process for forming a shape
of chevrons.
[0222] Subsequently, about 10 nm of a thin nickel layer was formed
on the surface of the thin film by a sputtering. Then, the base
member was subjected to an electroforming process under the same
condition as Example 1 in a nickel sulfamate bath to precipitate
nickel until the thickness of nickel became 250 .mu.m. The base
member on which the nickel was deposited as described above was
mechanically peeled off from the nickel electroforming body. Then,
the following process was repeated three times. An acrylic-based UV
curable resin was applied on the nickel electroforming body from
which the base member was peeled off; the applied acrylic-based UV
curable resin was cured; and then the cured resin was peeled off.
Further, the nickel electroforming body was immersed in Chemizol
2303 manufactured by The Japan Cee-Bee Chemical Co., Ltd., followed
by being cleaned while being stirred for 2 hours at a temperature
of 50 degrees Celsius. Accordingly, polymer component(s), adhered
to a part of the surface of the electroforming body, which
was(were) visually confirmed was(were) removed.
[0223] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained. Subsequently, a silicone-based polymer
[a resin composition of a mixture of 90% by mass of a silicone
rubber (manufactured by Wacker Chemie AG under the product name of
"Elastosil RT601") and 10% by mass of a curing agent] was applied
onto the nickel mold by a dropping method, then cured by being
heated at 50 degrees Celsius for 1 hour, and thereafter detached
from the nickel mold. Thus, a silicone rubber to which the surface
profile of the nickel mold was transferred was obtained. Further, a
fluorine-based UV curable resin was applied on a glass for which a
silane coupling process had been performed. After the silicone
rubber was pressed against the fluorine-based UV curable resin, the
fluorine-based UV curable resin was cured by irradiation with
ultraviolet rays at 600 mJ/cm.sup.2 and then the silicone rubber
was peeled off. Accordingly, a diffraction grating formed of the
glass substrate, in which the concavity and convexity pattern of a
fluorine-based resin was formed, was obtained.
[0224] For the concavity and convexity pattern of the diffraction
grating, the concavity and convexity shape on the surface was
analyzed by using the atomic force microscope used in Example 1 to
obtain an analysis image. Analysis conditions of the atomic force
microscope were the same as those in Example 1.
[0225] FIG. 8C shows the obtained concavity and convexity analysis
image. For comparison, FIG. 8A shows a concavity and convexity
analysis image of the concavity and convexity pattern of the block
copolymer from which PMMA was selectively removed by the etching
process; and FIG. 8B shows a concavity and convexity analysis image
of the concavity and convexity pattern for which the process for
forming the shape of chevrons was performed in the second anneal
step after the etching process. It was found out that the patterns
shown in FIGS. 8A, 8B, and 8C had a common pattern regularity
and/or common pattern pitch and that the planar shape of the
concavity and convexity pattern of the block copolymer from which
PMMA was selectively removed by the etching process was
satisfactorily reflected by the second annealing process and the
transfer of the mold to the resin.
[0226] FIG. 8D shows a concavity and convexity analysis image of
the cross-section in the vicinity of the surface of the obtained
diffraction grating. From the analysis images of the surfaces of
the diffraction grating, an average height of the concavities and
convexities, an average pitch of the concavities and convexities,
an average value (m) and a median (M) of a depth distribution of
the concavities and convexities, and a kurtosis of the concavities
and convexities of the diffraction grating were each obtained in
the same manner as Example 1. The results thereof are described as
follows.
Average height: 58 nm Average pitch: 300 nm Average value (m) of
depth distribution: 51.96 nm Median (M) of depth distribution:
55.56 nm
Kurtosis: -1.142
[0227] FIG. 8E shows a Fourier-transformed image obtained from the
analysis images. As is apparent from the result shown in FIG. 8E,
it was observed that the Fourier-transformed image showed a
circular pattern substantially centered at an origin at which an
absolute value of wavenumber was 0 .mu.m.sup.-1, and that the
circular pattern was present within a region where the absolute
value of wavenumber was within a range of 10 .mu.m.sup.-1 or
less.
[0228] On the UV curable resin film as the diffraction grating
obtained as described above, a transparent electrode (ITO,
thickness: 120 nm), a hole transporting layer
(N,N-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine,
thickness: 40 nm), an electron transporting layer
(8-hydroxyquinoline aluminum, thickness: 30 nm), a lithium fluoride
layer (thickness: 1.5 nm), and a metal electrode (aluminum,
thickness: 100 nm) were each stacked by a vapor deposition method
to maintain the shape of the concavities and convexities formed on
the surface of the cured resin layer. Accordingly, the organic EL
element was obtained.
<Evaluation of Light Emission Efficiency of Organic EL
Element>
[0229] A light emission efficiency of the organic EL element
obtained in this example was measured in the same manner as Example
2. FIG. 8F shows a relation between a current efficiency and a
luminance L' of the organic EL element; FIG. 8G shows a relation
between a power efficiency and the luminance L' of the organic EL
element. In each of FIG. 8F and FIG. 8G, square marks indicate
results of this example and circular dots indicate results of the
organic EL element produced by stacking each layer on a glass
substrate in which the concavity and convexity pattern of the
diffraction grating is not formed, in the same manner as described
above. From the result shown in FIG. 8F, it was found that the
current efficiency of the organic EL element of this example at a
luminance of 500 to 2000 cd/m.sup.2 was more than twice that of the
organic EL element having no concavity and convexity on the glass
substrate. Further, from the result shown in FIG. 8G, it was found
that the current efficiency of the organic EL element of this
example at the luminance of 500 to 2000 cd/m.sup.2 was about 3
times that of the organic EL element having no concavity and
convexity on the glass substrate. Therefore, the organic EL element
of the present invention had an external extraction efficiency
sufficiently.
<Evaluation of Light Emission Directivity of Organic EL
Element>
[0230] The directivity of light emission of the organic EL element
obtained in this example was evaluated in the similar manner as
Example 2. That is, the organic EL element in a luminescent state
was visually observed in all the directions (directions of all
around 360.degree.). Neither particularly bright sites nor
particularly dark sites were observed when the organic EL element
obtained in Example 4 was observed in any of the directions of all
around 360.degree., and the brightness was uniform in all the
directions. In this way, it was shown that the directivity of light
emission of the organic EL element of the present invention was
sufficiently low.
Example 5
[0231] Toluene was added to 150 mg of the block copolymer 4 and 23
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution.
[0232] Subsequently, 0.7 g of octadecyl trichlorosilane (OTS) was
added to 500 ml of heptane, followed by being stirred to prepare
2.0 mM of OTS solution. A glass substrate after cleaning having a
thickness of 1.1 mm was immersed in the solution and stationarily
placed for 24 hours. This processed substrate was subjected to
ultrasonic cleaning with chloroform for 10 minutes and then
subjected to ultrasonic cleaning with pure water for 10 minutes,
followed by being dried. Accordingly, an OTS-processed glass
substrate was obtained.
[0233] The obtained block copolymer solution was applied, on the
OTS-processed glass substrate, in a film thickness of 200 to 250
nm, by a spin coating. The spin coating was performed at a spin
speed of 500 rpm for 10 seconds, and then performed at a spin speed
of 800 rpm for 30 seconds. After the spin coating, the thin film
was left at a room temperature for 10 minutes until the thin film
was dried.
[0234] Subsequently, the base member was heated for 8 hours in an
oven of 150 degrees Celsius (first annealing process). It was
observed that concavities and convexities were formed on the thin
film on the surface of the heated base member and that micro phase
separation of the block copolymer was caused.
[0235] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetone,
and was subjected to cleaning with ion-exchanged water, followed by
being dried. By performing the etching process, PMMA on the base
member was selectively removed to obtain a thin film with a minute
concavity and convexity pattern.
[0236] The base member was subjected to a heating process (second
annealing process) for 1 hour in an oven of 125 degrees Celsius so
that the thin film was subjected to a process for forming a shape
of chevrons.
[0237] Subsequently, about 30 nm of a thin nickel layer was formed
on the surface of the thin film by a vapor deposition method. Then,
the base member was subjected to an electroforming process under
the same condition as Example 1 in a nickel sulfamate bath to
precipitate nickel until the thickness of nickel became 250 .mu.m.
The base member on which the nickel was deposited as described
above was mechanically peeled off from the nickel electroforming
body. Then, the following process was repeated three times. An
acrylic-based UV curable resin was applied on the nickel
electroforming body from which the base member was peeled off; the
applied acrylic-based UV curable resin was cured; and then the
cured resin was peeled off. Further, the nickel electroforming body
was immersed in Chemisol 2303 manufactured by The Japan Cee-Bee
Chemical Co., Ltd., followed by being cleaned while being stirred
for 2 hours at 50 degrees Celsius. Accordingly, polymer
component(s), adhered to a part of the surface of the
electroforming body, which was(were) visually confirmed was(were)
removed.
[0238] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained. Subsequently, a fluorine-based UV
curable resin was applied on a PET substrate (COSMOSHINE A-4100
manufactured by Toyobo Co., Ltd.). After the nickel mold was
pressed against the fluorine-based UV curable resin, the
fluorine-based UV curable resin was cured by irradiation with
ultraviolet rays at 600 mJ/cm.sup.2 and then the nickel mold was
peeled off. Accordingly, a diffraction grating made of a UV curable
resin film to which the surface profile of the nickel mold was
transferred was obtained. For the concavity and convexity pattern
of the diffraction grating, the concavity and convexity shape on
the surface was analyzed by using the atomic force microscope used
in Example 1 to obtain an analysis image. Analysis conditions of
the atomic force microscope were the same as those in Example
1.
[0239] FIG. 9A shows the obtained concavity and convexity analysis
image. Further, FIG. 9B shows the obtained concavity and convexity
analysis image of the cross-section. From the analysis images, an
average height of the concavities and convexities, an average pitch
of the concavities and convexities, an average value (m) and a
median (M) of a depth distribution of the concavities and
convexities, and a kurtosis of the concavities and convexities were
each obtained in the same manner as Example 1.
The results thereof are described as follows. Average height: 40 nm
Average pitch: 110 nm Average value (m) of depth distribution:
59.84 nm Median (M) of depth distribution: 61.06 nm
Kurtosis: 0.729
[0240] FIG. 9C shows a Fourier-transformed image obtained from the
analysis images. As is apparent from the result shown in FIG. 9C,
it was observed that the Fourier-transformed image showed a
circular pattern substantially centered at an origin at which an
absolute value of wavenumber was 0 .mu.m.sup.-1, and that the
circular pattern was present within a region where the absolute
value of wavenumber was within a range of 10 .mu.m.sup.-1 or
less.
[0241] On the UV curable resin film as the diffraction grating
obtained as described above, a transparent electrode (ITO,
thickness: 120 nm), a hole transporting layer
(N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine,
thickness: 40 nm), an electron transporting layer
(8-hydroxyquinoline aluminum, thickness: 30 nm), a lithium fluoride
layer (thickness: 1.5 nm), and a metal electrode (aluminum,
thickness: 100 nm) were each stacked by a vapor deposition method
to maintain the shape of the concavities and convexities formed on
the surface of the cured resin layer. Accordingly, the organic EL
element was obtained.
Example 6
[0242] Toluene was added to 120 mg of the block copolymer 2 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution.
[0243] Subsequently, 170 mg of methyltrimethoxysilane (MTMS) and 89
mg of 1,2-bis(trimethoxysilyl)ethane (BTMSE) were added to 4.75 g
of methylisobutylketone, followed by being stirred to prepare
methyltrimethoxysilane/1,2-bis(trimethoxysilyl)ethane solution.
This solution was applied on a glass substrate after cleaning
having a thickness of 1.1 mm by a spin coating to obtain a glass
substrate with a coating film made of
methyltrimethoxysilane/1,2-bis(trimethoxysilyl)ethane. The spin
coating was performed at a spin speed of 500 rpm for 10 seconds,
and then performed at a spin speed of 800 rpm for 30 seconds.
Thereafter, the glass substrate with the coating film was sintered
for 6 hours in a nitrogen atmosphere at a temperature of 280
degrees Celsius to obtain an organo silicate processed glass
substrate.
[0244] The obtained block copolymer solution was applied, on the
organo silicate processed glass substrate, in a film thickness of
200 to 250 nm, by a spin coating. The spin coating was performed at
a spin speed of 500 rpm for 10 seconds, and then performed at a
spin speed of 800 rpm for 30 seconds. After the spin coating, the
thin film was left at a room temperature for 10 minutes until the
thin film was dried.
[0245] Subsequently, the base member was heated for 5 hours in an
oven of 160 degrees Celsius (first annealing process). It was
observed that concavities and convexities were formed on the thin
film on the surface of the heated base member and that micro phase
separation of the block copolymer was caused.
[0246] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetone,
and was subjected to cleaning with ion-exchanged water, followed by
being dried. By performing the etching process, PMMA on the base
member was selectively removed to obtain a thin film with a minute
concavity and convexity pattern.
[0247] The base member was subjected to a heating process (second
annealing process) for 85 hours in an oven of 110 degrees Celsius
so that the thin film was subjected to a process for forming a
shape of chevrons.
[0248] Subsequently, about 10 nm of a thin nickel layer was formed
on the surface of the thin film by a sputtering. Then, the base
member was subjected to an electroforming process under the same
condition as Example 1 in a nickel sulfamate bath to precipitate
nickel until the thickness of nickel became 250 .mu.m. The base
member on which the nickel was deposited as described above was
mechanically peeled off from the nickel electroforming body. The
nickel electroforming body from which the base member was peeled
off was immersed in Chemisol 2303 manufactured by The Japan Cee-Bee
Chemical Co., Ltd., followed by being cleaned while being stirred
for 2 hours at 50 degrees Celsius. Thereafter, the nickel
electroforming body was immersed in a tetrahydrofuran solution and
an ultrasonic cleaning process was carried out for 30 minutes.
Accordingly, polymer component(s), adhered to a part of the surface
of the electroforming body, which was(were) visually confirmed
was(were) removed.
[0249] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained. Subsequently, a fluorine-based UV
curable resin was applied on a PET substrate (COSMOSHINE A-4100
manufactured by Toyobo Co., Ltd.). After the nickel mold was
pressed against the fluorine-based UV curable resin, the
fluorine-based UV curable resin was cured by irradiation with
ultraviolet rays at 600 mJ/cm.sup.2 and then the nickel mold was
peeled off. Accordingly, a diffraction grating made of the UV
curable resin film to which the surface profile of the nickel mold
was transferred was obtained. For the concavity and convexity
pattern of the diffraction grating, the concavity and convexity
shape on the surface was analyzed by using the atomic force
microscope used in Example 1 to obtain an analysis image. Analysis
conditions of the atomic force microscope were the same as those in
Example 1.
[0250] FIG. 10C shows the obtained concavity and convexity analysis
image. For comparison, FIG. 10A shows a concavity and convexity
analysis image of the concavity and convexity pattern of the block
copolymer from which PMMA was selectively removed by the etching
process; and FIG. 10B shows a concavity and convexity analysis
image of the concavity and convexity pattern of the mold formed by
the electroforming. The pattern shown in FIG. 10B showed the
inverted pattern, of the pattern shown in FIG. 10A, which was
transferred from the pattern shown in FIG. 10A. From FIGS. 10A,
10B, and 10C, it was found out that the patterns of FIGS. 10A, 10B,
and 10C had a common pattern regularity and/or common pattern pitch
and that the planar shape of the concavity and convexity pattern of
the block copolymer from which PMMA was selectively removed by the
etching process was satisfactorily reflected by the electroforming
and the transfer of the mold to the resin.
[0251] FIG. 10D shows a concavity and convexity analysis image of
the cross-section in the vicinity of the surface of the obtained
diffraction grating. From the analysis images of the surfaces of
the diffraction grating, an average height of the concavities and
convexities, an average pitch of the concavities and convexities,
an average value (m) and a median (M) of a depth distribution of
the concavities and convexities, and a kurtosis of the concavities
and convexities of the diffraction grating were each obtained in
the same manner as Example 1. The results thereof are described as
follows.
Average height: 72 nm Average pitch: 380 nm Average value (m) of
depth distribution: 61.43 nm Median (M) of depth distribution:
63.69 nm
Kurtosis: -1.091
[0252] FIG. 10E shows a Fourier-transformed image obtained from the
analysis images. As is apparent from the result shown in FIG. 10E,
it was observed that the Fourier-transformed image showed a
circular pattern substantially centered at an origin at which an
absolute value of wavenumber was 0 .mu.m.sup.-1, and that the
circular pattern was present within a region where the absolute
value of wavenumber was within a range of 10 .mu.m.sup.-1 or
less.
[0253] On the UV curable resin film as the diffraction grating
obtained as described above, a transparent electrode (ITO,
thickness: 120 nm), a hole transporting layer
(N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine,
thickness: 40 nm), an electron transporting layer
(8-hydroxyquinoline aluminum, thickness: 30 nm), a lithium fluoride
layer (thickness: 1.5 nm), and a metal electrode (aluminum,
thickness: 100 nm) were each stacked by a vapor deposition method
to maintain the shape of the concavities and convexities formed on
the surface of the cured resin layer. Accordingly, the organic EL
element was obtained.
Example 7
[0254] Toluene was added to 120 mg of the block copolymer 2 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution.
[0255] Subsequently, 170 mg of methyltrimethoxysilane (MTMS) and 89
mg of 1,2-bis(trimethoxysilyl)ethane (BTMSE) were added to 4.75 g
of methylisobutylketone, followed by being stirred to prepare
methyltrimethoxysilane/1,2-bis(trimethoxysilyl)ethane solution.
This solution was applied on a glass substrate after cleaning
having a thickness of 1.1 mm by a spin coating to obtain a glass
substrate with a coating film made of
methyltrimethoxysilane/1,2-bis(trimethoxysilyl)ethane. The spin
coating was performed at a spin speed of 500 rpm for 10 seconds,
and then performed at a spin speed of 800 rpm for 30 seconds.
Thereafter, the glass substrate with the coating film was sintered
for 6 hours in a nitrogen atmosphere at a temperature of 280
degrees Celsius to obtain an organo silicate processed glass
substrate.
[0256] The obtained block copolymer solution was applied, on the
organo silicate processed glass substrate, in a film thickness of
200 to 250 nm, by a spin coating. The spin coating was performed at
a spin speed of 500 rpm for 10 seconds, and then performed at a
spin speed of 800 rpm for 30 seconds. After the spin coating, the
thin film was left at a room temperature for 10 minutes until the
thin film was dried.
[0257] Subsequently, the substrate was heated for 5 hours in an
oven of 160 degrees Celsius (annealing process). It was observed
that concavities and convexities were formed on the thin film on
the surface of the heated base member and that micro phase
separation of the block copolymer was caused.
[0258] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetone,
and was subjected to cleaning with ion-exchanged water, followed by
being dried. By performing the etching process, PMMA on the base
member was selectively removed to obtain a thin film with a minute
concavity and convexity pattern.
[0259] The base member was subjected to a heating process (second
annealing process) for 20 minutes in an oven of 170 degrees Celsius
so that the thin film was subjected to a process for forming a
shape of chevrons.
[0260] Subsequently, about 10 nm of a thin nickel layer was formed
on the surface of the thin film by a sputtering. Then, the base
member was subjected to an electroforming process under the same
condition as Example 1 in a nickel sulfamate bath to precipitate
nickel until the thickness of nickel became 250 .mu.m. The base
member on which the nickel was deposited as described above was
mechanically peeled off from the nickel electroforming body. The
nickel electroforming body from which the base member was peeled
off was immersed in Chemisol 2303 manufactured by The Japan Cee-Bee
Chemical Co., Ltd., followed by being cleaned while being stirred
for 2 hours at 50 degrees Celsius. Thereafter, the nickel
electroforming body was immersed in a tetrahydrofuran solution and
an ultrasonic cleaning process was carried out for 30 minutes.
Accordingly, polymer component(s), adhered to a part of the surface
of the electroforming body, which was(were) visually confirmed
was(were) removed.
[0261] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained. Subsequently, a fluorine-based UV
curable resin was applied on the nickel mold. After a glass, for
which a silane coupling process had been performed, was pressed
against the fluorine-based UV curable resin, the fluorine-based UV
curable resin was cured by irradiation with ultraviolet rays at 600
mJ/cm.sup.2 and then the nickel mold was peeled off. Accordingly, a
diffraction grating made of the glass substrate on which the
concavity and convexity pattern of the fluorine-based resin, to
which the surface profile of the nickel mold was transferred, was
formed was obtained. For the concavity and convexity pattern of the
diffraction grating, the concavity and convexity shape on the
surface was analyzed by using the atomic force microscope used in
Example 1 to obtain an analysis image. Analysis conditions of the
atomic force microscope were the same as those in Example 1.
[0262] FIG. 11B shows the obtained concavity and convexity analysis
image. For comparison, FIG. 11A shows a concavity and convexity
analysis image of the concavity and convexity pattern of the block
copolymer from which PMMA was selectively removed by the etching
process. From FIGS. 11A and 11B, it was found out that the patterns
shown in FIGS. 11A and 11B had a common pattern regularity and/or
common pattern pitch and that the planar shape of the concavity and
convexity pattern of the block copolymer from which PMMA was
selectively removed by the etching process was satisfactorily
reflected by the transfer of the mold to the resin.
[0263] FIG. 11C shows a concavity and convexity analysis image of
the cross-section in the vicinity of the surface of the obtained
diffraction grating. From the analysis images of the surfaces of
the diffraction grating, an average height of the concavities and
convexities, an average pitch of the concavities and convexities,
an average value (m) and a median (M) of a depth distribution of
the concavities and convexities, and a kurtosis of the concavities
and convexities of the diffraction grating were each obtained in
the same manner as Example 1. The results thereof are described as
follows.
Average height: 68 nm Average pitch: 420 nm Average value (m) of
depth distribution: 49.88 nm Median (M) of depth distribution:
54.27 nm
Kurtosis: -0.518
[0264] FIG. 11D shows a Fourier-transformed image obtained from the
analysis images. As is apparent from the result shown in FIG. 11D,
it was observed that the Fourier-transformed image showed a
circular pattern substantially centered at an origin at which an
absolute value of wavenumber was 0 .mu.m.sup.-1, and that the
circular pattern was present within a region where the absolute
value of wavenumber was within a range of 10 .mu.m.sup.-1 or
less.
[0265] On the UV curable resin film as the diffraction grating
obtained as described above, a transparent electrode (ITO,
thickness: 120 nm), a hole transporting layer
(N,N'-diphenyl-N,N-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine,
thickness: 40 nm), an electron transporting layer
(8-hydroxyquinoline aluminum, thickness: 30 nm), a lithium fluoride
layer (thickness: 1.5 nm), and a metal electrode (aluminum,
thickness: 100 nm) were each stacked by a vapor deposition method
to maintain the shape of the concavities and convexities formed on
the surface of the cured resin layer. Accordingly, the organic EL
element was obtained.
Example 8
[0266] Toluene was added to 120 mg of the block copolymer 1 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution. The obtained block copolymer
solution was applied, on a polyphenylene sulfide film (TORELINA
manufactured by TORAY INDUSTRIES, INC.), in a film thickness of 200
to 250 nm, by a spin coating. The spin coating was performed at a
spin speed of 500 rpm for 10 seconds, and then performed at a spin
speed of 800 rpm for 30 seconds. The thin film applied by the spin
coating was left at a room temperature for 10 minutes until the
thin film was dried.
[0267] Subsequently, the base member was heated for 3 hours in an
oven of 170 degrees Celsius (first annealing process). It was
observed that concavities and convexities were formed on the thin
film on the surface of the heated base member and that micro phase
separation of the block copolymer was caused. The cross-section of
the thin film was observed with the transmission electron
microscope used in Example 1. As shown in the micrograph of FIG.
12A, which is obtained by the transmission electron microscope, PS
portions correspond to black portions and PMMA portions correspond
to white portions as a result of RuO.sub.4 staining.
[0268] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetic
acid, and was subjected to cleaning with ion-exchanged water,
followed by being dried. By performing the etching process, PMMA on
the base member was selectively removed to obtain a thin film with
a minute concavity and convexity pattern.
[0269] The base member was subjected to a heating process (second
annealing process) for 1 hour in an oven of 140 degrees Celsius so
that the thin film was subjected to a process for forming a shape
of chevrons.
[0270] Subsequently, about 10 nm of a thin nickel layer was formed
on the surface of the thin film by a sputtering. Then, the base
member was subjected to an electroforming process under the same
condition as Example 1 in a nickel sulfamate bath to precipitate
nickel until the thickness of nickel became 250 .mu.m. The base
member on which the nickel was deposited as described above was
mechanically peeled off from the nickel electroforming body. The
nickel electroforming body from which the base member was peeled
off was immersed in Chemisol 2303 manufactured by The Japan Cee-Bee
Chemical Co., Ltd., followed by being cleaned while being stirred
for 2 hours at 50 degrees Celsius. Thereafter, the nickel
electroforming body was immersed in a tetrahydrofuran solution and
an ultrasonic cleaning process was carried out for 30 minutes.
Then, the following process was repeated three times. An
acrylic-based UV curable resin was applied on the nickel
electroforming body; the applied acrylic-based UV curable resin was
cured; and then the cured resin was peeled off. Accordingly,
polymer component(s) adhered to a part of the surface of the
electroforming body was(were) removed. FIG. 12B shows a measurement
result of the cross-section of the nickel electroforming body using
the SEM. It is understood from FIG. 12B that concavities and
convexities of the nickel electroforming body were smooth and the
cross-section of each convex portion had a chevron shape.
[0271] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained. Subsequently, a fluorine-based UV
curable resin was applied on a PET substrate (COSMOSHINE A-4100
manufactured by Toyobo Co., Ltd.). After the nickel mold was
pressed against the fluorine-based UV curable resin, the
fluorine-based UV curable resin was cured by irradiation with
ultraviolet rays at 600 mJ/cm.sup.2 and then the nickel mold was
peeled off. Accordingly, a diffraction grating made of the UV
curable resin film to which the surface profile of the nickel mold
was transferred was obtained. For the concavity and convexity
pattern of the diffraction grating, the concavity and convexity
shape on the surface was analyzed by using the atomic force
microscope used in Example 1 to obtain an analysis image. Analysis
conditions of the atomic force microscope were the same as those in
Example 1.
[0272] FIG. 12E shows a concavity and convexity analysis image of
the surface of the resin of the obtained diffraction grating. For
comparison, FIG. 12C shows a concavity and convexity analysis image
of the concavity and convexity pattern of the block copolymer from
which PMMA was selectively removed by the etching process and FIG.
5D shows a concavity and convexity analysis image of the concavity
and convexity pattern of the mold formed by the electroforming. The
pattern shown in FIG. 12D was a pattern transferred from the
pattern shown in FIG. 12C, and thus the pattern shown in FIG. 12D
was the inverted pattern of the pattern shown in FIG. 12C. It was
found out that patterns of FIGS. 12C, 12D, and 12E had a common
pattern regularity and/or common pattern pitch and that the
concavity and convexity pattern of the block copolymer from which
PMMA was selectively removed by the etching process was
satisfactorily reflected by the electroforming and the transfer to
the resin to be thereafter performed.
[0273] FIG. 12F shows a concavity and convexity analysis image of
the cross-section in the vicinity of the resin surface of the
obtained diffraction grating. From the analysis images of the
concavities and convexities of the diffraction grating shown in
FIGS. 12E and 12F, an average height of the concavities and
convexities, an average pitch of the concavities and convexities, a
Fourier-transformed image, an average value and a median of a depth
distribution of the concavities and convexities, and a kurtosis of
the concavities and convexities were each obtained in the same
manner as Example 1. The results thereof are described as
follows.
Average height: 51 nm Average pitch: 290 nm Average value (m) of
depth distribution: 45.67 nm Median (M) of depth distribution:
46.69 nm
Kurtosis: -0.054
[0274] FIG. 12G shows a Fourier-transformed image obtained from the
analysis images. As is apparent from the result shown in FIG. 12G,
it was observed that the Fourier-transformed image showed a
circular pattern substantially centered at an origin at which an
absolute value of wavenumber was 0 .mu.m.sup.-1, and that the
circular pattern was present within a region where the absolute
value of wavenumber was within a range of 10 .mu.m.sup.-1 or
less.
[0275] On the UV curable resin film as the diffraction grating
obtained as described above, a transparent electrode (ITO,
thickness: 120 nm), a hole transporting layer
(N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine,
thickness: 40 nm), an electron transporting layer
(8-hydroxyquinoline aluminum, thickness: 30 nm), a lithium fluoride
layer (thickness: 1.5 nm), and a metal electrode (aluminum,
thickness: 100 nm) were each stacked by a vapor deposition method
to maintain the shape of the concavities and convexities formed on
the surface of the cured resin layer. Accordingly, the organic EL
element was obtained.
Example 9
[0276] Toluene was added to 120 mg of the block copolymer 2 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution.
[0277] Subsequently, 170 mg of methyltrimethoxysilane (MTMS) and 89
mg of 1,2-bis(trimethoxysilyl)ethane (BTMSE) were added to 4.75 g
of methylisobutylketone, followed by being stirred to prepare
methyltrimethoxysilane/1,2-bis(trimethoxysilyl)ethane solution.
This solution was applied on a glass substrate after cleaning
having a thickness of 1.1 mm by a spin coating to obtain a glass
substrate with a coating film made of
methyltrimethoxysilane/1,2-bis(trimethoxysilyl)ethane. The spin
coating was performed at a spin speed of 500 rpm for 10 seconds,
and then performed at a spin speed of 800 rpm for 30 seconds. The
glass substrate with the coating film was sintered for 6 hours in a
nitrogen atmosphere at a temperature of 320 degrees Celsius to
obtain an organo silicate processed glass substrate.
[0278] The obtained block copolymer solution was applied, on the
organo silicate processed glass substrate, in a film thickness of
200 to 250 nm, by a spin coating. The spin coating was performed at
a spin speed of 500 rpm for 10 seconds, and then performed at a
spin speed of 800 rpm for 30 seconds. After the spin coating, the
thin film was left at a room temperature for 10 minutes until the
thin film was dried.
[0279] Subsequently, the base member was heated for 24 hours in an
oven of 160 degrees Celsius (first annealing process). It was
observed that concavities and convexities were formed on the thin
film on the surface of the heated base member and that micro phase
separation of the block copolymer was caused.
[0280] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetone,
and was subjected to cleaning with ion-exchanged water, followed by
being dried. By performing the etching process, PMMA on the
substrate was selectively removed to obtain a thin film with a
minute concavity and convexity pattern.
[0281] The base member was subjected to a heating process (second
annealing process) for 1 hour in an oven of 125 degrees Celsius so
that the thin film was subjected to a process for forming a shape
of chevrons.
[0282] Subsequently, about 10 nm of a thin nickel layer was formed
on the surface of the thin film by a sputtering. Then, the base
member was subjected to an electroforming process under the same
condition as Example 1 in a nickel sulfamate bath to precipitate
nickel until the thickness of nickel became 250 .mu.m. The base
member on which the nickel was deposited as described above was
mechanically peeled off from the nickel electroforming body. The
nickel electroforming body from which the base member was peeled
off was immersed in Chemisol 2303 manufactured by The Japan Cee-Bee
Chemical Co., Ltd., followed by being cleaned while being stirred
for 2 hours at 50 degrees Celsius. Thereafter, the following
process was repeated three times. An acrylic-based UV curable resin
was applied on the nickel electroforming body; the applied
acrylic-based UV curable resin was cured; and then the cured resin
was peeled off. Accordingly, polymer component(s) adhered to a part
of the surface of the electroforming body was(were) removed.
[0283] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained. Subsequently, a fluorine-based UV
curable resin was applied on a PET substrate (COSMOSHINE A-4100
manufactured by Toyobo Co., Ltd.). After the nickel mold was
pressed against the fluorine-based UV curable resin, the
fluorine-based UV curable resin was cured by irradiation with
ultraviolet rays at 600 mJ/cm.sup.2 and then the nickel mold was
peeled off. Accordingly, a diffraction grating made of the UV
curable resin film to which the surface profile of the nickel mold
was transferred was obtained. For the concavity and convexity
pattern of the diffraction grating, the concavity and convexity
shape on the surface was analyzed by using the atomic force
microscope used in Example 1 to obtain an analysis image. Analysis
conditions of the atomic force microscope were the same as those in
Example 1.
[0284] FIG. 13D shows the obtained concavity and convexity analysis
image. For comparison, FIG. 13A shows a concavity and convexity
analysis image of the concavity and convexity pattern of the block
copolymer from which PMMA was selectively removed by the etching
process; FIG. 13B shows a concavity and convexity analysis image of
the concavity and convexity pattern for which the process for
forming the shape of chevrons was performed in the second anneal
step after the etching process; and FIG. 13C shows a concavity and
convexity analysis image of the concavity and convexity pattern of
the mold formed by the electroforming. The pattern shown in FIG.
13C was a pattern transferred from the pattern shown in FIG. 13A,
and thus the pattern shown in FIG. 13C was the inverted pattern of
those shown in FIGS. 13A, 13B, and 13D. It was found out that
patterns of FIGS. 13A, 13B, 13C, and 13D had a common pattern
regularity and/or common pattern pitch and that the planar shape of
the concavity and convexity pattern of the block copolymer from
which PMMA was selectively removed by the etching process was
satisfactorily reflected by the second annealing process, the
electroforming, and the transfer to the resin to be thereafter
performed.
[0285] FIG. 13E shows a concavity and convexity analysis image of
the cross-section in the vicinity of the surface of the obtained
diffraction grating. From the concavity and convexity analysis
images (FIGS. 13D and 13E) of the surfaces of the diffraction
grating, an average height of the concavities and convexities, an
average pitch of the concavities and convexities, an average value
(m) and a median (M) of a depth distribution of the concavities and
convexities, and a kurtosis of the concavities and convexities of
the diffraction grating were each obtained in the same manner as
Example 1. The results thereof are described as follows.
Average height: 110 nm Average pitch: 290 nm Average value (m) of
depth distribution: 91.22 nm Median (M) of depth distribution: 95.9
nm
Kurtosis: -0.348
[0286] FIG. 13F shows a Fourier-transformed image obtained from the
analysis images. As is apparent from the result shown in FIG. 13F,
it was observed that the Fourier-transformed image showed a
circular pattern substantially centered at an origin at which an
absolute value of wavenumber was 0 .mu.m.sup.-1, and that the
circular pattern was present within a region where the absolute
value of wavenumber was within a range of 10 .mu.m.sup.-1 or
less.
[0287] On the UV curable resin film as the diffraction grating
obtained as described above, a transparent electrode (ITO,
thickness: 120 nm), a hole transporting layer
(N,N-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-diphenyl-4,4'-diamine,
thickness: 40 nm), an electron transporting layer
(8-hydroxyquinoline aluminum, thickness: 30 nm), a lithium fluoride
layer (thickness: 1.5 nm), and a metal electrode (aluminum,
thickness: 100 nm) were each stacked by a vapor deposition method
to maintain the shape of the concavities and convexities formed on
the surface of the cured resin layer. Accordingly, the organic EL
element was obtained.
Comparative Example 1
[0288] A nickel electroforming body was obtained in the similar
manner as Example 1, except that the heating process (second
annealing process) for 1 hour in the oven of 140 degrees Celsius
was not performed. FIG. 14A shows a SEM measurement result of the
cross-section of the nickel electroforming body. The concavity and
convexity shape on the surface of the nickel electroforming body
was measured by using the atomic force microscope used in Example 1
to obtain an analysis image. Analysis conditions of the atomic
force microscope were the same as those in Example 1. The obtained
analysis image is shown in FIG. 14C. For comparison, FIG. 14B shows
a concavity and convexity analysis image of the concavity and
convexity pattern of the block copolymer from which PMMA was
selectively removed by the etching process.
[0289] As is clear from FIG. 14A, regarding the nickel
electroforming body obtained in this example, the concavities and
convexities on the surface were ununiform and coarse as compared
with those obtained in Example 1, and further portions like
overhangs were observed. Furthermore, it was found that polystyrene
(portions look black) was remained at each concave portion of the
nickel surface. In FIG. 14C, the periodic concavity and convexity
pattern which appeared in FIG. 14B was not observed. Therefore, it
is considered that the concavity and convexity pattern of the block
copolymer from which PMMA was selectively removed by the etching
process had a cross-section structure (see FIG. 1C) which was not
suitable for the transfer even by the electroforming.
Comparative Example 2
[0290] A nickel electroforming body was obtained in the similar
manner as Example 8, except that the heating process (second
annealing process) for 1 hour in the oven of 140 degrees Celsius
was not performed. FIG. 15A shows a SEM measurement result of the
cross-section of the nickel electroforming body. The concavity and
convexity shape of the nickel electroforming body was measured by
using the atomic force microscope used in Example 1 to obtain an
analysis image. Analysis conditions of the atomic force microscope
were the same as those in Example 1. The obtained analysis image is
shown in FIG. 15C. For comparison, FIG. 15B shows a concavity and
convexity analysis image of the concavity and convexity pattern of
the block copolymer from which PMMA was selectively removed by the
etching process.
[0291] As is clear from FIG. 15A, regarding the nickel
electroforming body obtained in this example, the concavities and
convexities on the surface were ununiform and coarse as compared
with those obtained in Example 8, and further portions like
overhangs were observed. Furthermore, it was found that polystyrene
(portions look black) was remained at each concave portion of the
nickel. In FIG. 15C, the periodic concavity and convexity pattern
which appeared in FIG. 15B was not observed. Therefore, it is
considered that the concavity and convexity pattern of the block
copolymer from which PMMA was selectively removed by the etching
process had a cross-section structure which was not suitable for
the transfer by the electroforming.
Comparative Example 3
[0292] Toluene was added to 120 mg of the block copolymer 1 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution.
[0293] Subsequently, 0.7 g of octadecyldimethylchlorosilane (ODS)
was added to 500 ml of heptane, followed by being stirred to
prepare 2.0 mM of ODS solution. A glass substrate after cleaning
having a thickness of 1.1 mm was immersed in the solution and
stationarily placed for 24 hours. This processed substrate was
subjected to ultrasonic cleaning with chloroform for 10 minutes and
then subjected to ultrasonic cleaning with pure water for 10
minutes, followed by being dried. Accordingly, an ODS-processed
glass substrate was obtained.
[0294] The obtained block copolymer solution was applied, on the
ODS-processed glass substrate, in a film thickness of 200 to 250
nm, by a spin coating. The spin coating was performed at a spin
speed of 500 rpm for 10 seconds, and then performed at a spin speed
of 800 rpm for 30 seconds. After the spin coating, the thin film
was left at a room temperature for 10 minutes until the thin film
was dried.
[0295] Subsequently, the base member was heated for 3 hours in an
oven of 160 degrees Celsius (annealing process). It was observed
that concavities and convexities were formed on the thin film on
the surface of the heated base member and that micro phase
separation of the block copolymer was caused.
[0296] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetone,
and was subjected to cleaning with ion-exchanged water, followed by
being dried. By performing the etching process, PMMA on the base
member was selectively removed to obtain a thin film with a minute
concavity and convexity pattern.
[0297] Subsequently, about 10 nm of a thin nickel layer was formed
on the surface of the thin film by a sputtering. Then, the base
member was subjected to an electroforming process under the same
condition as Example 1 in a nickel sulfamate bath to precipitate
nickel until the thickness of nickel became 250 .mu.m. The base
member on which the nickel was deposited as described above was
mechanically peeled off from the nickel electroforming body. The
nickel electroforming body from which the base member was peeled
off was immersed in Chemisol 2303 manufactured by The Japan Cee-Bee
Chemical Co., Ltd., followed by being cleaned while being stirred
for 2 hours at 50 degrees Celsius. Thereafter, the nickel
electroforming body was immersed in a tetrahydrofuran solution and
an ultrasonic cleaning process was carried out for 30 minutes.
[0298] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained. Then, a fluorine-based UV curable
resin was applied on a PET substrate (COSMOSHINE A-4100
manufactured by Toyobo Co., Ltd.). After the nickel mold was
pressed against the fluorine-based UV curable resin, the
fluorine-based UV curable resin was cured by irradiation with
ultraviolet rays at 600 mJ/cm.sup.2 and then the nickel mold was
peeled off. Accordingly, a diffraction grating made of the UV
curable resin film to which the surface profile of the nickel mold
was transferred was obtained. For the concavity and convexity
pattern of the diffraction grating, the concavity and convexity
shape on the surface was analyzed by using the atomic force
microscope used in Example 1 to obtain an analysis image. However,
the shape representing the concavity and convexity on the surface
was not observed in the analysis image. For reference, the analysis
image of the concavity and convexity pattern of the block copolymer
from which PMMA was selectively removed by the etching process and
the analysis image of concavity and convexity pattern of the
surface of the nickel electroforming body were each obtained by
performing measurement using the atomic force microscope used in
Example 1. Analysis conditions of the atomic force microscope were
the same as those in Example 1. Respective analysis images are
shown in FIGS. 16A and 16B.
[0299] It was found out that the periodic concavity and convexity
pattern which appeared in FIG. 16A did not appear at all in FIG.
16B. Therefore, it is considered that the concavity and convexity
pattern of the block copolymer from which PMMA was selectively
removed by the etching process had a cross-section structure which
was not suitable for the transfer by the electroforming.
Comparative Example 4
[0300] Toluene was added to 120 mg of the block copolymer 1 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution. The obtained block copolymer
solution was applied, on a polyphenylene sulfide film (TORELINA
manufactured by TORAY INDUSTRIES, INC.), in a film thickness of 200
to 250 nm, by a spin coating. The spin coating was performed at a
spin speed of 500 rpm for 10 seconds, and then performed at a spin
speed of 800 rpm for 30 seconds. The thin film applied by the spin
coating was left at a room temperature for 10 minutes until the
thin film was dried.
[0301] Subsequently, the base member was heated for 5 hours in an
oven of 170 degrees Celsius (first annealing process). It was
observed that concavities and convexities were formed on the thin
film on the surface of the heated base member and that micro phase
separation of the block copolymer was caused.
[0302] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetic
acid, and was subjected to cleaning with ion-exchanged water,
followed by being dried. By performing the etching process, PMMA on
the base member was selectively removed to obtain a thin film with
a minute concavity and convexity pattern.
[0303] Subsequently, about 10 nm of a thin nickel layer was formed
on the surface of the thin film by a sputtering without performing
the second annealing process. Then, the base member was subjected
to an electroforming process under the same condition as Example 1
in a nickel sulfamate bath to precipitate nickel until the
thickness of nickel became 250 .mu.m. The base member on which the
nickel was deposited as described above was mechanically peeled off
from the nickel electroforming body. The nickel electroforming body
from which the base member was peeled off was immersed in Chemisol
2303 manufactured by The Japan Cee-Bee Chemical Co., Ltd., followed
by being cleaned while being stirred for 2 hours at 50 degrees
Celsius. Thereafter, the nickel electroforming body was immersed in
a tetrahydrofuran solution and an ultrasonic cleaning process was
carried out for 30 minutes.
[0304] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained. Subsequently, a fluorine-based UV
curable resin was applied on a PET substrate (COSMOSHINE A-4100
manufactured by Toyobo Co., Ltd.). The fluorine-based UV curable
resin was cured by irradiation with ultraviolet rays at 600
mJ/cm.sup.2 while the nickel mold was pressed against the
fluorine-based UV curable resin. Then, the nickel mold was peeled
off from the cured resin. Accordingly, a diffraction grating made
of the UV curable resin film to which the surface profile of the
nickel mold was transferred was obtained. For the concavity and
convexity pattern of the diffraction grating, the concavity and
convexity shape on the surface was analyzed by using the atomic
force microscope used in Example 1. However, the shape representing
the concavity and convexity on the surface was not observed in the
analysis image. For reference, the analysis image of the concavity
and convexity pattern of the block copolymer from which PMMA was
selectively removed by the etching process and the analysis image
of the concavity and convexity pattern on the surface of the nickel
electroforming body were each obtained by performing measurement
using the atomic force microscope used in Example 1. Analysis
conditions of the atomic force microscope were the same as those in
Example 1. Respective analysis images are shown in FIGS. 17A and
17B.
[0305] It was found out that the periodic concavity and convexity
pattern which appeared in FIG. 17A did not appear in FIG. 17B.
Therefore, it is considered that the concavity and convexity
pattern of the block copolymer from which PMMA was selectively
removed by the etching process had a cross-section structure which
was not suitable for the transfer by the electroforming.
Comparative Example 5
[0306] Toluene was added to 120 mg of the block copolymer 5 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution.
[0307] Subsequently, 0.7 g of octadecyl trichlorosilane (OTS) was
added to 500 ml of heptane, followed by being stirred to prepare
2.0 mM of OTS solution. A glass substrate after cleaning having a
thickness of 1.1 mm was immersed in the solution and stationarily
placed for 24 hours. This processed substrate was subjected to
ultrasonic cleaning with chloroform for 10 minutes and then
subjected to ultrasonic cleaning with pure water for 10 minutes,
followed by being dried. Accordingly, an OTS-processed glass
substrate was obtained.
[0308] The obtained block copolymer solution was applied, on the
OTS-processed glass substrate, in a film thickness of 200 to 250
nm, by a spin coating. The spin coating was performed at a spin
speed of 500 rpm for 10 seconds, and then performed at a spin speed
of 800 rpm for 30 seconds. After the spin coating, the thin film
was left at a room temperature for 10 minutes until the thin film
was dried.
[0309] Subsequently, the base member was heated for 8 hours in an
oven of 190 degrees Celsius (first annealing process). It was
observed that concavities and convexities were formed on the thin
film on the surface of the heated base member and that micro phase
separation of the block copolymer was caused.
[0310] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetone,
and was subjected to cleaning with ion-exchanged water, followed by
being dried. By performing the etching process, PMMA on the base
member was selectively removed to obtain a thin film with a minute
concavity and convexity pattern.
[0311] Subsequently, about 30 nm of a thin nickel layer was formed
on the surface of the thin film by a vapor deposition method
without performing the second annealing process. Then, the base
member was subjected to an electroforming process under the same
condition as Example 1 in a nickel sulfamate bath to precipitate
nickel until the thickness of nickel became 250 .mu.m. The base
member on which the nickel was deposited as described above was
mechanically peeled off from the nickel electroforming body. Then,
the following process was repeated three times. An acrylic-based UV
curable resin was applied on the nickel electroforming body from
which the base member was peeled off; the applied acrylic-based UV
curable resin was cured; and then the cured resin was peeled off.
Further, the nickel electroforming body was immersed in Chemisol
2303 manufactured by The Japan Cee-Bee Chemical Co., Ltd., followed
by being cleaned while being stirred for 2 hours at 50 degrees
Celsius. Accordingly, polymer component(s), adhered to a part of
the surface of the electroforming body, which was(were) visually
confirmed was(were) removed.
[0312] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained. Subsequently, a fluorine-based UV
curable resin was applied on a PET substrate (COSMOSHINE A-4100
manufactured by Toyobo Co., Ltd.). After the nickel mold was
pressed against the fluorine-based UV curable resin, the
fluorine-based UV curable resin was cured by irradiation with
ultraviolet rays at 600 mJ/cm.sup.2 and then the nickel mold was
peeled off. Accordingly, a diffraction grating made of the UV
curable resin film to which the surface profile of the nickel mold
was transferred was obtained.
[0313] For the concavity and convexity pattern of the surface of
the nickel electroforming body, the analysis image was obtained by
performing measurement using the atomic force microscope used in
Example 1. Analysis conditions of the atomic force microscope were
the same as those in Example 1. The analysis image is shown in FIG.
18. Although the second annealing process was not performed in this
example, it was found out from FIG. 18 that the periodic concavity
and convexity pattern appeared on the surface of the diffraction
grating while it was unclear (the pattern was not as clear as that
of Example 1). The reason thereof is considered that the molecular
weight of the block copolymer 5 was relatively low.
Comparative Example 6
[0314] Toluene was added to 120 mg of the block copolymer 2 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution. The obtained block copolymer
solution was applied, on a polyphenylene sulfide film (TORELINA
manufactured by TORAY INDUSTRIES, INC.), in a film thickness of 200
to 250 nm, by a spin coating to form a thin film. The spin coating
was performed at a spin speed of 500 rpm for 10 seconds, and then
performed at a spin speed of 800 rpm for 30 seconds. The thin film
applied by the spin coating was left at a room temperature for 10
minutes until the thin film was dried.
[0315] Subsequently, the base member was heated for 5 hours in an
oven of 170 degrees Celsius (first annealing process).
[0316] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetic
acid, and was subjected to cleaning with ion-exchanged water,
followed by being dried. By performing the etching process, PMMA on
the base member was selectively removed to obtain a thin film with
a minute concavity and convexity pattern.
[0317] Subsequently, about 30 nm of a thin nickel layer was formed
on the surface of the thin film by a vapor deposition method. Then,
the base member was subjected to an electroforming process under
the same condition as Example 1 in a nickel sulfamate bath to
precipitate nickel until the thickness of nickel became 250 .mu.m.
The base member on which the nickel was deposited as described
above was mechanically peeled off from the nickel electroforming
body. Then, the following process was repeated three times. An
acrylic-based UV curable resin was applied on the nickel
electroforming body from which the base member was peeled off; the
applied acrylic-based UV curable resin was cured; and then the
cured resin was peeled off. Further, the nickel electroforming body
was immersed in Chemisol 2303 manufactured by The Japan Cee-Bee
Chemical Co., Ltd., followed by being cleaned while being stirred
for 2 hours at 50 degrees Celsius. Accordingly, polymer
component(s), adhered to a part of the surface of the
electroforming body, which was(were) visually confirmed was(were)
removed.
[0318] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained.
[0319] Subsequently, a fluorine-based UV curable resin was applied
on a PET substrate (COSMOSHINE A-4100 manufactured by Toyobo Co.,
Ltd.). After the nickel electroforming body was pressed against the
fluorine-based UV curable resin, the fluorine-based UV curable
resin was cured by irradiation with ultraviolet rays at 600
mJ/cm.sup.2 and then the nickel mold was peeled off. Accordingly, a
diffraction grating made of the UV curable resin film to which the
surface profile of the nickel mold was transferred was obtained.
For the concavity and convexity pattern of the diffraction grating,
the concavity and convexity shape on the surface was measured by
using the atomic force microscope used in Example 1. However, the
concavity and convexity shape on the surface was not observed. For
reference, the analysis image of the concavity and convexity
pattern of the surface of the nickel electroforming body was
obtained by performing measurement using the atomic force
microscope used in Example 1. Analysis conditions of the atomic
force microscope were the same as those in Example 1. The obtained
analysis image is shown in FIG. 19. It was found out that the
periodic concavity and convexity pattern did not appear at all in
FIG. 19.
Comparative Example 7
[0320] Toluene was added to 120 mg of the block copolymer 1 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution. The obtained block copolymer
solution was applied, on a polyphenylene sulfide film (TORELINA
manufactured by TORAY INDUSTRIES, INC.), in a film thickness of 200
to 250 nm, by a spin coating. The spin coating was performed at a
spin speed of 500 rpm for 10 seconds, and then performed at a spin
speed of 800 rpm for 30 seconds. The thin film applied by the spin
coating was left at a room temperature for 10 minutes until the
thin film was dried.
[0321] Subsequently, the base member was heated for 6 hours in an
oven of 160 degrees Celsius (first annealing process).
[0322] The heated thin film was subjected to an etching process as
described below. The thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the thin film was immersed in acetic
acid, and was subjected to cleaning with ion-exchanged water,
followed by being dried. By performing the etching process, PMMA on
the base member was selectively removed to obtain a thin film with
a minute concavity and convexity pattern.
[0323] Subsequently, about 30 nm of a thin nickel layer was formed
on the surface of the thin film by a vapor deposition method. Then,
the base member was subjected to an electroforming process under
the same condition as Example 1 in a nickel sulfamate bath to
precipitate nickel until the thickness of nickel became 250 .mu.m.
The base member on which the nickel was deposited as described
above was mechanically peeled off from the nickel electroforming
body. Then, the following process was repeated three times. An
acrylic-based UV curable resin was applied on the nickel
electroforming body from which the base member was peeled off; the
applied acrylic-based UV curable resin was cured; and then the
cured resin was peeled off. Further, the nickel electroforming body
was immersed in Chemisol 2303 manufactured by The Japan Cee-Bee
Chemical Co., Ltd., followed by being cleaned while being stirred
for 2 hours at 50 degrees Celsius. Accordingly, polymer
component(s), adhered to a part of the surface of the
electroforming body, which was(were) visually confirmed was(were)
removed.
[0324] Subsequently, the nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained. Subsequently, a fluorine-based UV
curable resin was applied on a PET substrate (COSMOSHINE A-4100
manufactured by Toyobo Co., Ltd.). After the nickel mold was
pressed against the fluorine-based UV curable resin, the
fluorine-based UV curable resin was cured by irradiation with
ultraviolet rays at 600 mJ/cm.sup.2 and then the nickel mold was
peeled off. Accordingly, a diffraction grating made of the UV
curable resin film to which the surface profile of the nickel mold
was transferred was obtained. For the concavity and convexity
pattern of the diffraction grating, the concavity and convexity
shape on the surface was measured by using the atomic force
microscope used in Example 1. However, the concavity and convexity
shape on the surface was not observed. For reference, the analysis
image of the concavity and convexity pattern of the surface of the
nickel electroforming body was obtained by performing measurement
using the atomic force microscope used in Example 1. Analysis
conditions of the atomic force microscope were the same as those in
Example 1. The obtained analysis image is shown in FIG. 20. It was
found out that the periodic concavity and convexity pattern did not
appear at all in FIG. 20.
Comparative Example 8
[0325] Toluene was added to 120 mg of the block copolymer 2 and 30
mg of Polyethylene Glycol 4000 manufactured by Tokyo Chemical
Industry Co., Ltd. so that the total amount thereof was 10 g,
followed by dissolving them. Then, it was filtrated or filtered
through a membrane filter having a pore diameter of 0.5 .mu.m to
obtain a block copolymer solution. Subsequently, 170 mg of
methyltrimethoxysilane (MTMS) and 89 mg of
1,2-bis(trimethoxysilyl)ethane (BTMSE) were added to 4.75 g of
methylisobutylketone, followed by being stirred to prepare
methylisobutylketone/1,2-bis(trimethoxysilyl)ethane solution. This
solution was applied on a glass substrate after cleaning having a
thickness of 1.1 mm by a spin coating to obtain a glass substrate
with a coating film made of
methylisobutylketone/1,2-bis(trimethoxysilyl)ethane. The spin
coating was performed at a spin speed of 500 rpm for 10 seconds,
and then performed at a spin speed of 800 rpm for 30 seconds.
[0326] The glass substrate with the coating film was sintered for 6
hours in a nitrogen atmosphere at a temperature of 280 degrees
Celsius to obtain an organo silicate processed glass substrate. The
prepared block copolymer solution was applied on the organo
silicate processed glass substrate by a spin coating to form a thin
film. The spin coating was performed at a spin speed of 500 rpm for
10 seconds, and then performed at a spin speed of 800 rpm for 30
seconds. After the spin coating, the thin film was left at a room
temperature for 10 minutes.
[0327] Subsequently, the glass substrate with the thin film was
subjected to an annealing process for 5 hours in an oven of 160
degrees Celsius (first annealing process). In order to selectively
remove PMMA from the obtained thin film by an etching, the glass
substrate with the thin film was irradiated with ultraviolet rays
at an irradiation intensity of 30 J/cm.sup.2 by use of a high
pressure mercury lamp. Then, the glass substrate with the thin film
was immersed in acetone, and was subjected to cleaning with
ion-exchanged water, followed by being dried. By removing PMMA as
described above, a concavity and convexity thin film which was
substantially made of PS was obtained.
[0328] The glass substrate with the thin film was subjected to a
heating process for 80 hours in an oven of 95 degrees Celsius which
was lower than the glass transition temperature of PS. After the
heating process, about 10 nm of a thin nickel layer was formed on
the surface of the concavity and convexity thin film by a
sputtering. Then, the substrate was subjected to an electroforming
process under the same condition as Example 1 in a nickel sulfamate
bath to precipitate nickel until the thickness of nickel became 250
.mu.m. The glass substrate with the thin film was mechanically
peeled off from the obtained nickel electroforming body. The
surface of the nickel electroforming body from which the substrate
was peeled off was immersed in Chemisol 2303 manufactured by The
Japan Cee-Bee Chemical Co., Ltd., followed by being cleaned while
being stirred for 2 hours at 50 degrees Celsius. Thereafter,
transfer was performed three times using an acrylic-based UV
curable resin. The nickel electroforming body was immersed in
HD-2101TH manufactured by Daikin Chemicals Sales, Co., Ltd. for
about 1 minute and was dried, and then stationarily placed
overnight. The next day, the nickel electroforming body was
immersed in HDTH manufactured by Daikin Chemicals Sales, Co., Ltd.
to perform an ultrasonic cleaning process for about 1 minute.
Accordingly, a nickel mold for which a mold-release treatment had
been performed was obtained.
[0329] Subsequently, a fluorine-based UV curable resin was applied
on a PET substrate (COSMOSHINE A-4100 manufactured by Toyobo Co.,
Ltd.). Then, the fluorine-based UV curable resin was cured by
irradiation with ultraviolet rays at 600 mJ/cm.sup.2 while pressing
the nickel mold against the fluorine-based UV curable resin.
Accordingly, a PET substrate with the resin to which the surface
profile of the nickel mold was transferred was obtained. For the
PET substrate with the resin obtained as described above, the
concavity and convexity shape on the resin surface was analyzed by
using the atomic force microscope used in Example 1. However, the
shape representing the concavity and convexity on the surface was
not observed in the analysis image. For reference, the analysis
image of the concavity and convexity pattern of the block copolymer
from which PMMA was selectively removed by the etching process and
the analysis image of the concavity and convexity pattern of the
surface of the nickel electroforming body were each obtained by
performing measurement using the atomic force microscope used in
Example 1. Analysis conditions of the atomic force microscope were
the same as those in Example 1. Respective analysis images are
shown in FIGS. 21A and 21B.
[0330] It was found out that the periodic concavity and convexity
pattern which appeared in FIG. 21A did not appear at all in FIG.
21B. Therefore, it is considered that the concavity and convexity
pattern of the block copolymer from which PMMA was selectively
removed by the etching process had a cross-section structure which
was not suitable for the transfer by the electroforming.
[0331] From the results of Examples 1 to 9 and Comparative Examples
1 to 4 and 6 to 8 as described above, it is found out that the
concavity and convexity pattern of the thin film in which the micro
phase separation was caused was not satisfactorily transferred to
the nickel layer, in a case that the nickel layer was deposited by
the electroforming without the second annealing process of the thin
film for which the etching process was performed. In Comparative
Example 5, since the molecular weight of the block copolymer was
relatively low (not more than 500,000), the concavity and convexity
pattern was transferred to the nickel electroforming body without
the second annealing process. However, as understood from
Comparative Examples 6 and 7, in a case that the molecular weight
of the block copolymer exceeded 500,000, the concavity and
convexity pattern could not be transferred to the nickel
electroforming body at all without the second annealing process.
Therefore, it is found out that, regardless of the molecular weight
of the block copolymer, the second annealing process is required to
obtain a mold having a desired minute pattern. In particular, in a
case that a device such as the diffraction grating to be produced
by the mold is used in a wide visible region, a pitch such that
diffraction is generated in such a wavelength region is required.
Thus, the molecular weight of the block copolymer in which the
micro phase separation is caused desirably exceeds 500,000.
[0332] As understood from the results of the current efficiency and
the power efficiency in Examples 2 and 4, the organic EL element of
the present invention has superior light-extraction efficiency.
Further, as is apparent from the measurement results of directivity
of light emission of the organic EL element in these Examples, the
directivity of light emission of the organic EL element of the
present invention is sufficiently low.
[0333] In the above Example(s), the diffraction grating, of which
the average height of the concavities and convexities was within a
range from 40 to 110 nm, and the average pitch was within a range
from 110 to 480 nm, was obtained. It was confirmed that the
satisfactory diffraction was generated, provided that the average
height and the average pitch of the concavities and convexities of
the diffraction grating were at least within the above ranges.
Further, in the above Example(s), the diffraction grating, of which
the kurtosis of the concavities and convexities was within a range
from -1.2 to 0.729, was obtained. It was found out that, if the
kurtosis was at least within the above range, the satisfactory
diffracted light was generated and no leak current was generated.
Regarding the cross-section shape of the concavity and convexity
structure formed in the diffraction grating obtained in the above
Example(s), it was found that the average value m and the median M
of the depth distribution of the concavities and convexities on the
cross-section satisfied the following empiric formula:
(1.062m-2.2533).times.0.95.ltoreq.M.ltoreq.(1.062m-2.2533).times.1.05
Example 10
[0334] In this example, a nickel mold (nickel substrate), for which
a mold-release treatment was performed, was obtained by using a BCP
method similar to Example 1. Subsequently, a fluorine-based UV
curable resin was applied on a PET substrate (easily-adhesion PET
film manufactured by Toyobo Co., Ltd., product name: COSMOSHINE
A-4100). Then, the fluorine-based UV curable resin was cured by
irradiation with ultraviolet rays at 600 mJ/cm.sup.2, with the
nickel mold being pressed thereto. After curing of the resin, the
nickel mold was peeled off from the cured resin. Accordingly, a
diffraction grating mold made of the PET substrate with the resin
film to which the surface profile of the nickel mold was
transferred was obtained. 2.5 g of tetraethoxysilane (TEOS) and 2.1
g of methyltriethoxysilane (MTES) were added by drops to a mixture
of 24.3 g of ethanol, 2.16 g of water, and 0.0094 g of concentrated
hydrochloric acid, followed by being stirred for 2 hours at a
temperature of 23 degrees Celsius and humidity of 45% to obtain a
sol solution. The sol solution was applied on a soda-lime glass
plate of 15.times.15.times.0.11 cm by a bar coating. Doctor Blade
(manufactured by Yoshimitsu Seiki Co., Ltd.) was used as a bar
coater. The doctor blade was designed so that the film thickness of
the coating film was 5 However, the doctor blade was adjusted so
that the film thickness of the coating film was 40 by sticking an
imide tape having the thickness of 35 .mu.m to the doctor blade.
When 60 seconds have elapsed after the application of the sol
solution, the diffraction grating mold, made of the PET substrate
with the resin film to which the surface profile of the nickel mold
was transferred, which was prepared similar to Example 1, was
pressed against the coating film on the glass plate by a pressing
roll using a method described below.
[0335] At first, the surface on which the pattern of the mold has
been formed was pressed against the coating film on the glass
substrate while rotating the pressing roll of which temperature was
23 degrees Celsius from one end to the other end of the glass
substrate. Immediately after completion of the pressing, the
substrate was moved on a hot plate and then heated at a temperature
of 100 degrees Celsius (pre-sintering). After continuing the
heating for 5 minutes, the substrate was removed from the hot plate
and the mold was manually peeled off from the substrate from the
edge. The mold was peeled off such that an angle (peel angle) of
the mold with respect to the substrate was about 30.degree..
[0336] Subsequently, a main sintering was performed by heating the
substrate for 60 minutes in an oven of 300 degrees Celsius, and
then the pattern transferred to the coating film was evaluated.
[0337] For the diffraction grating, the analysis image of the
concavity and convexity shape on the resin surface was obtained by
using the atomic force microscope used in Example 1. Analysis
conditions of the atomic force microscope were the same as those in
Example 1.
<Average Height of Concavities and Convexities>
[0338] A concavity and convexity analysis image was obtained as
described above by performing a measurement in a randomly selected
measuring region of 3 .mu.m square (length: 3 .mu.m, width: 3
.mu.m) in the diffraction grating. Distances between randomly
selected concave portions and convex portions in the depth
direction were measured at 100 points or more in the concavity and
convexity analysis image, and the average of the distances was
calculated as the average height (depth) of the concavities and
convexities. The average height of the concavity and convexity
pattern obtained by the analysis image in this example was 56
nm.
<Fourier-Transformed Image>
[0339] A concavity and convexity analysis image was obtained by
performing a measurement in a randomly selected measuring region of
3 .mu.m square (length: 3 .mu.m, width: 3 .mu.m) in the diffraction
grating similar to Example 1. It was confirmed that the
Fourier-transformed image showed a circular pattern substantially
centered at an origin at which an absolute value of wavenumber was
0 .mu.m.sup.-1, and that the circular pattern was present within a
region where the absolute value of wavenumber was within a range of
10 .mu.m.sup.-1 or less.
[0340] As a result of the image analysis of the obtained
Fourier-transformed image, the wavenumber 2.38 .mu.m.sup.-1 was the
most intensive. That is, the average pitch was 420 nm. The average
pitch could be obtained as follows. For each of the points of
Fourier-transformed image, intensity and distance (unit:
.mu.m.sup.-1) from the origin of Fourier-transformed image were
obtained. Then, the average value of the intensity was obtained for
the points each having the same distance from the origin. As
described above, a relation between the distance from the origin of
the Fourier-transformed image and the average value of the
intensity was plotted, a fitting with a spline function was carried
out, and the wavenumber of peak intensity was regarded as the
average wavenumber (.mu.m.sup.-1). For the average pitch, it is
allowable to make a calculation by another method, for example, a
method for obtaining the average pitch of the concavities and
convexities as follows. That is, a concavity and convexity analysis
image is obtained by performing a measurement in a randomly
selected measuring region of 3 .mu.m square (length: 3 .mu.m,
width: 3 .mu.m) in the diffraction grating, then the distances
between randomly selected adjacent convex portions or between
randomly selected adjacent concave portions are measured at 100
points or more in the concavity and convexity analysis image, and
then an average of these distances is determined.
<Manufacture of Organic EL Element>
[0341] A glass substrate with a pattern made of a sol-gel material
layer as the diffraction grating obtained as described above was
cleaned with a brush to remove foreign matter and the like adhered
thereto, then organic matter and the like was removed by an
alkaline cleaner and an organic solvent. On the substrate cleaned
as described above, a film of ITO having the thickness of 120 nm
was formed at a temperature of 300 degrees Celsius by a sputtering
method. A photoresist was applied and an exposure was performed
with an electrode mask pattern, and then an etching was performed
by a developer. Accordingly, a transparent electrode having a
predetermined pattern was obtained. The obtained transparent
electrode was cleaned with a brush, and organic matter and the like
was removed by an alkaline cleaner and an organic solvent. Then,
transparent electrode was subjected to a UV-ozone process. On the
transparent electrode processed as described above, a hole
transporting layer (4,4',4'' tris(9-carbazole)triphenylamine,
thickness: 35 nm), a light emitting layer
(tris(2-phenylpyridinato)iridium(III) complex-doped
4,4',4''tris(9-carbazole)triphenylamine, thickness: 15 nm;
tris(2-phenylpyridinato)iridium(III) complex-doped
1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene, thickness: 15 nm),
an electron transporting layer
(1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene, thickness: 65 nm),
and a lithium fluoride layer (thickness: 1.5 nm) were each stacked
by a vapor deposition method, and further a metal electrode
(aluminum, thickness: 50 nm) was formed by the vapor deposition
method. Accordingly, as shown in FIG. 22, the organic EL element
200, which has a coating film (sol-gel material layer) 42, a
transparent electrode 92, an organic layer 94 (a hole transporting
layer 95, a light-emitting layer 96, and an electron transporting
layer 97), and a metal electrode 98 on a substrate 40 in this
order, was obtained.
[0342] In the process as described above, the substrate was formed
of the sol-gel material and had the superior mechanical strength.
Thus, even when the cleaning with the brush was performed for the
substrate and the surface of the concavity and convexity pattern
after formation of the transparent electrode as described above,
damage, adhesion of the foreign matter, projection on the
transparent electrode and the like were less likely to occur, and
thereby element failure therefrom could be suppressed. Therefore,
the obtained organic EL element was superior, as compared with a
case in which a curable resin substrate was used, in terms of the
mechanical strength of the substrate having the concavity and
convexity pattern. Further, the substrate made of the sol-gel
material produced in accordance with the method of this example had
satisfactory chemical resistance, and had alkali resistance
superior to the substrate formed of a curable resin material.
Therefore, the substrate of this example had a certain corrosion
resistance to alkaline fluid and the organic solvent used for the
cleaning step of the substrate and the transparent electrode, and
thus it is possible to use various cleaning liquids. Further, an
alkaline developer is used at the time of the patterning of the
transparent substrate in some cases. The substrate in this example
also has the corrosion resistance to such a developer. In this
respect, the substrate in this example has an advantage over the
curable resin substrate having generally low resistance in the
alkaline fluid. Further, the substrate formed of the sol-gel
material has superior UV resistance and superior weather resistance
as compared with the curable resin substrate. Therefore, the
substrate in this example also has resistance to a UV-ozone
cleaning process after the formation of the transparent electrode.
Further, in a case that the organic EL element produced by the
method of this example is used outside or outdoors, it is possible
to suppress deterioration due to sunlight as compared with the case
in which the curable resin substrate is used.
<Evaluation of Light Emission Efficiency of Organic EL
Element>
[0343] A light emission efficiency of the organic EL element
obtained in this example was measured by the following method. That
is, a voltage was applied to the obtained organic EL element, and
then the applied voltage V and a current I flowing through the
organic EL element were measured with a source measurement
instrument (manufactured by ADC CORPORATION, R6244), and a total
luminous flux amount L was measured with a total flux measurement
apparatus manufactured by Spectra Co-op. From the thus obtained
measured value of the applied voltage V, the current I, and the
total luminous flux amount L, a luminance value L' was calculated.
Here, for the current efficiency, the following calculation formula
(F1) was used:
Current efficiency=(L'/I).times.S (F1)
and, for the power efficiency, the following calculation formula
(F2) was used:
Power efficiency=(L'/I/V).times.S (F2)
Accordingly, the current efficiency and the power efficiency of the
organic EL element were calculated. In the above formulae, S is a
light-emitting or luminescent area of the element. Noted that the
value of the luminance L' was calculated on the assumption that
light distribution characteristic of the organic EL element
followed Lambert's law, and the following calculation formula (F3)
was used:
L'=L/.pi./S (F3)
[0344] The current efficiency of the organic EL element of this
example at a luminance of 1000 cd/m.sup.2 was about 1.4 times that
of the organic EL element having no concavity and convexity on the
glass substrate. Further, the current efficiency of the organic EL
element of this example at the luminance of 1000 cd/m.sup.2 was
about 1.6 times that of the organic EL element having no concavity
and convexity on the glass substrate. Therefore, the organic EL
element of the present invention had a sufficient external
extraction efficiency.
<Evaluation of Light Emission Directivity of Organic EL
Element>
[0345] The directivity of light emission of the organic EL element
obtained in this example was evaluated by the following method.
That is, the organic EL element in a luminescent state was visually
observed in all the directions (directions of all around)
360.degree.. Neither particularly bright sites nor particularly
dark sites were observed when the organic EL element obtained in
Example 3 was observed in any of the directions of all around
360.degree., and the brightness was uniform in all the directions.
In this way, it was shown that the directivity of light emission of
the organic EL element of the present invention was sufficiently
low.
[0346] As described above, a temperature at the time of forming the
film of the transparent electrode (ITO) of the organic EL element
in this example was 300 degrees Celsius. It is allowable that the
temperature at the time of forming the film of the transparent
electrode is lower than 300 degrees Celsius, but the transparent
electrode is desired to have low resistivity and the film formation
is preferably performed at a high temperature to increase
crystallinity. In a case that the temperature during the film
formation is low (about 100 degrees Celsius), an ITO film formed on
the substrate is relatively amorphous, has inferior specific
resistance, has inferior adhesion property between the substrate
and the ITO thin film. Although the concavity and convexity pattern
formed of a general UV curable resin and the like had difficulty in
withstanding a film formation step at a high temperature, the
concavity and convexity pattern can be applied even in the film
formation step at the high temperature by using the sol-gel
material which is an example of ceramic. Therefore, the method in
this example is also suitable for producing the substrate
(diffraction grating) for the organic EL element.
[0347] According to the present invention, it is possible to
produce a mold for nanoimprint, which is suitable for manufacturing
a diffraction grating used for a device such as an organic EL
element and has excellent mass producibility, easily and with high
accuracy. The diffraction grating obtained by using this mold and
the organic EL in which the diffracting grating is used have low
light directivity and superior light-extraction efficiency.
* * * * *