U.S. patent application number 14/748927 was filed with the patent office on 2015-11-05 for composition, laminate, method of manufacturing laminate, transistor, and method of manufacturing transistor.
This patent application is currently assigned to NIKON CORPORATION. The applicant listed for this patent is NIKON CORPORATION. Invention is credited to Yusuke KAWAKAMI, Shohei KOIZUMI, Kenji MIYAMOTO, Takashi SUGIZAKI.
Application Number | 20150318077 14/748927 |
Document ID | / |
Family ID | 51062273 |
Filed Date | 2015-11-05 |
United States Patent
Application |
20150318077 |
Kind Code |
A1 |
KOIZUMI; Shohei ; et
al. |
November 5, 2015 |
COMPOSITION, LAMINATE, METHOD OF MANUFACTURING LAMINATE,
TRANSISTOR, AND METHOD OF MANUFACTURING TRANSISTOR
Abstract
A composition includes the following (a) to (c). (a) an organic
compound having a hydroxy group; (b) a first cross-linking agent
that is at least one organic silicon compound selected from the
group including (b-1) an organic silicon compound including a
siloxane bond in the molecule and having three or more cyclic ether
groups in the molecule, (b-2) a chain organic silicon compound
including two or more siloxane bonds in the molecule and having two
or more cyclic ether groups in the molecule, (b-3) a cyclic organic
silicon compound including D unit in the molecule and having four
or more cyclic ether groups bonded to a silicon atom of the D unit
in the molecule, and (b-4) a cyclic organic silicon compound
including a T unit in the molecule and having two or more cyclic
ether groups in the molecule; and (c) a photocationic
polymerization initiator.
Inventors: |
KOIZUMI; Shohei; (Atsugi,
JP) ; SUGIZAKI; Takashi; (Yokohama, JP) ;
MIYAMOTO; Kenji; (Yokohama, JP) ; KAWAKAMI;
Yusuke; (Yokohama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NIKON CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
NIKON CORPORATION
Tokyo
JP
|
Family ID: |
51062273 |
Appl. No.: |
14/748927 |
Filed: |
June 24, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2014/050058 |
Jan 7, 2014 |
|
|
|
14748927 |
|
|
|
|
Current U.S.
Class: |
257/40 ; 428/447;
430/285.1; 430/325; 438/99 |
Current CPC
Class: |
G03F 7/004 20130101;
G03F 7/20 20130101; H01L 51/052 20130101; C08L 63/00 20130101; C08G
59/687 20130101; H01L 51/0023 20130101; G03F 7/0755 20130101; C08G
59/3254 20130101; H01L 51/0545 20130101; G03F 7/40 20130101; H01B
3/46 20130101; H01L 51/0015 20130101; G03F 7/038 20130101; Y10T
428/31663 20150401; G03F 7/0752 20130101; C08G 59/621 20130101;
H01L 51/0002 20130101; H01L 21/02126 20130101 |
International
Class: |
H01B 3/46 20060101
H01B003/46; G03F 7/20 20060101 G03F007/20; G03F 7/004 20060101
G03F007/004; H01L 51/05 20060101 H01L051/05; H01L 51/00 20060101
H01L051/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 7, 2013 |
JP |
2013-000631 |
Claims
1. A composition comprising: (a) an organic compound having a
hydroxy group; (b) a first cross-linking agent that is at least one
organic silicon compound selected from the group including (b-1) an
organic silicon compound including a siloxane bond in the molecule
and having three or more cyclic ether groups in the molecule, (b-2)
a chain organic silicon compound including two or more siloxane
bonds in the molecule and having two or more cyclic ether groups in
the molecule, (b-3) a cyclic organic silicon compound including a
siloxane unit (D unit) represented by R.sup.1R.sup.2SiO.sub.2/2 in
the molecule, any one of or both of R.sup.1 and R.sup.2 being a
cyclic ether group, and having four or more cyclic ether groups
bonded to a silicon atom of the D unit in the molecule, and (b-4) a
cyclic organic silicon compound including a siloxane unit (T unit)
represented by R.sup.3SiO.sub.3/2 in the molecule, R.sup.3 being a
cyclic ether group, and having two or more cyclic ether groups in
the molecule; and (c) a photocationic polymerization initiator.
2. The composition according to claim 1, wherein the two or more
cyclic ether groups included in the first cross-linking agent are
any one of or both of a group including an epoxy ring and a group
including an oxetanyl ring.
3. The composition according to claim 1, further comprising: (d) a
second cross-linking agent that is an organic compound having two
or more cyclic ether groups.
4. The composition according to claim 3, wherein a ratio of a sum
of mass of the first cross-linking agent and the second
cross-linking agent to a total sum of mass of the organic compound
having a hydroxy group, the first cross-linking agent, and the
second cross-linking agent is 40 mass % to 90 mass %, and a ratio
of mass of the second cross-linking agent to the total sum is 5
mass % to 30 mass %.
5. The composition according to claim 3, wherein the second
cross-linking agent is a compound having an aromatic ring.
6. The composition according to claim 5, wherein the second
cross-linking agent is a compound represented by Formula (d1)
below. ##STR00006## (R.sup.2 and R.sup.3 are each a cyclic ether
group. R.sup.2 and R.sup.3 may be identical to each other or may be
different from each other.)
7. The composition according to claim 6, wherein the cyclic ether
group included in the second cross-linking agent is any one of or
both of a group including an epoxy ring and a group including an
oxetanyl ring.
8. The composition according to claim 1, wherein the organic
compound having a hydroxy group includes a phenolic hydroxy
group.
9. A method of manufacturing a laminate, comprising: applying a
solution containing the composition according to claim 1 over a
conductive layer to form a coating film; selectively irradiating
the coating film with light including light having an absorption
wavelength of the photocationic polymerization initiator included
in the coating film to form a latent image in the light-irradiated
region of the coating film; and developing the coating film with an
alkaline solution to form an insulator layer.
10. The method of manufacturing a laminate according to claim 9,
further comprising: prior to forming the coating film, applying a
surface treatment on at least a region to be provided with the
coating film by using a silane coupling agent having a cyclic ether
group.
11. A laminate, comprising: a conductive layer; and an insulator
layer formed by cationic-polymerization of the composition
according to claim 1.
12. The laminate according to claim 11, wherein the conductive
layer is covered with the insulator layer.
13. A method of manufacturing a transistor, comprising: forming a
gate electrode on a substrate; applying a solution including the
composition according to claim 1 over the gate electrode to form a
coating film; selectively irradiating the coating film with light
including light having an absorption wavelength of a photocationic
polymerization initiator included in the coating film to form a
latent image in the light-irradiated region of the coating film;
developing the coating film with an alkaline solution to form an
insulator layer; and forming a source electrode and a drain
electrode on the surface of a layer including the insulator
layer.
14. The method of manufacturing a transistor according to claim 13,
further comprising: prior to forming the coating film, applying a
surface treatment on at least a region to be provided with the
coating film by using a first silane coupling agent having a cyclic
ether group.
15. The method of manufacturing a transistor according to claim 13,
wherein at least one of the gate electrode, the source electrode,
and the drain electrode is formed by: applying a formation material
containing a second silane coupling agent having a group capable of
capturing a metal, which is an electroless plating catalyst, to
form a base film; and capturing the metal on the surface of the
base film and then performing electroless plating.
16. The method of manufacturing a transistor according to claim 15,
wherein the source electrode and the drain electrode are formed by:
forming a source base film and a drain base film, each being the
base film; and then capturing the metal on the surface of each of
the source base film and the drain base film to perform electroless
plating.
17. The method of manufacturing a transistor according to claim 16,
wherein the source base film and the drain base film are formed as
a continuous film.
18. The method of manufacturing a transistor according to claim 15,
wherein the gate electrode is formed by: forming a gate base film,
which is the base film; and then capturing the metal on the surface
of the gate base film to perform electroless plating.
19. The method of manufacturing a transistor according to claim 15,
wherein the second silane coupling agent has an amino group.
20. The method of manufacturing a transistor according to claim 19,
wherein the second silane coupling agent is a primary amine or a
secondary amine.
21. The method of manufacturing a transistor according to claim 15,
wherein the layer including the insulator layer includes: the
insulator layer; and an organic semiconductor layer disposed on the
insulator layer and having a surface on which the source electrode
and the drain electrode are formed.
22. The method of manufacturing a transistor according to claim 15,
comprising: forming the source electrode and the drain electrode;
and then forming an organic semiconductor layer that is in contact
with surfaces of the source electrode and the drain electrode that
face each other.
23. The method of manufacturing a transistor according to claim 21,
comprising, prior to forming the source electrode and the drain
electrode: forming a resist layer having an opening corresponding
to the source electrode and the drain electrode and capturing the
metal on the surface of the base film formed on the surface exposed
at least in the opening; performing first electroless plating and
then removing the resist layer; and performing second electroless
plating on the surface of an electrode formed by the first
electroless plating to form the source electrode and the drain
electrode, wherein the energy level difference between the work
function of a metal material used in the second electroless plating
and the energy level of a molecular orbital used for electron
transfer in a formation material of the organic semiconductor layer
is smaller than the energy level difference between the work
function of a metal material used in the first electroless plating
and the energy level of the molecular orbital.
24. The method of manufacturing a transistor according to claim 13,
wherein the substrate is made of a non-metallic material.
25. The method of manufacturing a transistor according to claim 24,
wherein the substrate is made of a resin material.
26. The method of manufacturing a transistor according to claim 25,
wherein the substrate has flexibility.
27. A transistor, comprising: a source electrode and a drain
electrode; a gate electrode provided corresponding to a channel
between the source electrode and the drain electrode; a
semiconductor layer provided in contact with the source electrode
and the drain electrode; and an insulator layer disposed between
the source electrode and the gate electrode and between the drain
electrode and the gate electrode, wherein the insulator layer is
formed by cationic polymerization of the composition according to
claim 1.
28. The transistor according to claim 27, wherein at least one of
the gate electrode, the source electrode, and the drain electrode
is laminated on a base film containing a silane coupling agent
having a group capable of capturing a metal, which is an
electroless plating catalyst.
29. The transistor according to claim 27, wherein the semiconductor
layer is an organic semiconductor layer.
30. The transistor according to claim 29, wherein the source
electrode has a first electrode and a second electrode formed to
cover the first electrode; the drain electrode has a third
electrode and a fourth electrode formed to cover the third
electrode; the energy level difference between the work function of
a formation material of the second electrode and the energy level
of a molecular orbital used for electron transfer in a formation
material of the organic semiconductor layer is smaller than the
energy level difference between the work function of a formation
material of the first electrode and the energy level of the
molecular orbital; and the energy level difference between the work
function of a formation material of the fourth electrode and the
energy level of the molecular orbital used for electron transfer in
the formation material of the organic semiconductor layer is
smaller than the energy level difference between the work function
of a formation material of the third electrode and the energy level
of the molecular orbital.
31. The transistor according to claim 27, which is formed on a
substrate made of a non-metallic material.
32. The transistor according to claim 31, wherein the substrate is
made of a resin material.
33. The transistor according to claim 32, wherein the substrate has
flexibility.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This is a Continuation Application of International
Application No. PCT/JP2014/050058, filed on Jan. 7, 2014, which
claims priority on Japanese Patent Application No. 2013-000631,
filed on Jan. 7, 2013. The contents of the aforementioned
applications are incorporated herein by reference.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention relates to a composition, a laminate,
a method of manufacturing a laminate, a transistor, and a method of
manufacturing a transistor.
[0004] 2. Background
[0005] In the related art, a laminate of a conductive layer and an
insulator layer has been used in various electronic circuits.
[0006] The laminate having such a laminated structure is used, for
example, to achieve the miniaturization and high integration of
electronic circuits. Specifically, this laminate is used for a
printed circuit board, a condenser, a transistor, and the like,
each having a multilayer wiring structure.
[0007] When forming the above laminate, wirings (conductive layers)
to be laminated are insulated from each other by an insulator
layer. As the insulator layer, any of an inorganic insulator and an
organic insulator may be used (for example, refer to U.S. Pat. No.
5,946,551 and U.S. Pat. No. 6,232,157). Among these, the laminate
using an organic insulator is advantageous, compared to a laminate
using a conventional insulator layer using SiO.sub.2 as a formation
material, in that an insulator layer can be formed in a liquid
phase and in that a laminated structure can be formed at a lower
temperature without requiring a vacuum process.
[0008] In the laminate in which an organic insulator is used in an
insulator layer, there is proposed a technology of patterning an
insulator layer through a photoresist-free simple method by the
combination of polyvinyl phenol (PVP) and an epoxy group-containing
compound with a photopolymerization initiator (for example, refer
to Japanese Unexamined Patent Application, First Publication No.
2006-28497).
SUMMARY
[0009] However, when a laminate is formed using a resin substrate,
a developer used for patterning an insulator layer may dissolve or
swell the resin substrate. When an alkaline solution is used as a
developer, it is known that it is possible to prevent the resin
substrate from being dissolved or swelled, but a material in use
for an insulator layer developable by an alkaline solution has been
limited.
[0010] An object of an aspect of the present invention is to
provide a composition developable by an alkaline solution and
capable of forming an insulator layer.
[0011] Another object of an aspect of the present invention is to
provide a method of manufacturing a laminate using the composition,
a manufactured laminate, a method of manufacturing a transistor,
and a manufactured transistor.
[0012] A composition according to an aspect of the present
invention includes:
[0013] (a) an organic compound having a hydroxy group;
[0014] (b) a first cross-linking agent that is at least one organic
silicon compound selected from the group including [0015] (b-1) an
organic silicon compound including a siloxane bond in the molecule
and having three or more cyclic ether groups in the molecule,
[0016] (b-2) a chain organic silicon compound including two or more
siloxane bonds in the molecule and having two or more cyclic ether
groups in the molecule, [0017] (b-3) a cyclic organic silicon
compound including a siloxane unit (D unit) represented by
R.sup.1R.sup.2SiO.sub.2/2 in the molecule, any one of or both of
R.sup.1 and R.sup.2 being a cyclic ether group, and having four or
more cyclic ether groups bonded to a silicon atom of the D unit in
the molecule, and [0018] (b-4) a cyclic organic silicon compound
including a siloxane unit (T unit) represented by
R.sup.3SiO.sub.3/2 in the molecule, R.sup.3 being a cyclic ether
group, and having two or more cyclic ether groups in the molecule;
and
[0019] (c) a photocationic polymerization initiator.
[0020] A method of manufacturing a laminate according to another
aspect of the present invention includes: applying a solution
containing the above-described composition over a conductive layer
to form a coating film; selectively irradiating the coating film
with light including light having an absorption wavelength of the
photocationic polymerization initiator included in the coating film
to form a latent image in the light-irradiated region of the
coating film; and developing the coating film with an alkaline
solution to form an insulator layer.
[0021] A laminate according to another aspect of the present
invention includes: a conductive layer; and an insulator layer
formed by cationic-polymerization of the above-described
composition.
[0022] A method of manufacturing a transistor according to another
aspect of the present invention includes: forming a gate electrode
on a substrate; applying a solution including the above-described
composition over the gate electrode to form a coating film;
selectively irradiating the coating film with light including light
having an absorption wavelength of a photocationic polymerization
initiator included in the coating film to form a latent image in
the light-irradiated region of the coating film; developing the
coating film with an alkaline solution to form an insulator layer;
and forming a source electrode and a drain electrode on the surface
of a layer including the insulator layer.
[0023] A transistor according to another aspect of the present
invention includes: a source electrode and a drain electrode; a
gate electrode provided corresponding to a channel between the
source electrode and the drain electrode; a semiconductor layer
provided in contact with the source electrode and the drain
electrode; and an insulator layer disposed between the source
electrode and the gate electrode and between the drain electrode
and the gate electrode, wherein the insulator layer is formed by
cationic polymerization of the above-described composition.
[0024] According to an aspect of the present invention, it is
possible to provide a composition developable by an alkaline
solution and capable of forming an insulator layer. According to
another aspect of the present invention, it is possible to provide
a method of manufacturing a laminate using the composition, a
manufactured laminate, a method of manufacturing a transistor, and
a manufactured transistor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1A is a process view showing a method of manufacturing
a laminate according to a first embodiment.
[0026] FIG. 1B is a process view showing the method of
manufacturing a laminate according to the first embodiment.
[0027] FIG. 1C is a process view showing the method of
manufacturing a laminate according to the first embodiment.
[0028] FIG. 2 is a schematic cross-sectional view showing a
transistor of a second embodiment.
[0029] FIG. 3A is a process view showing a manufacturing method of
the second embodiment.
[0030] FIG. 3B is a process view showing the manufacturing method
of the second embodiment.
[0031] FIG. 3C is a process view showing the manufacturing method
of the second embodiment.
[0032] FIG. 3D is a process view showing the manufacturing method
of the second embodiment.
[0033] FIG. 3E is a process view showing the manufacturing method
of the second embodiment.
[0034] FIG. 3F is a process view showing the manufacturing method
of the second embodiment.
[0035] FIG. 3G is a process view showing the manufacturing method
of the second embodiment.
[0036] FIG. 3H is a process view showing the manufacturing method
of the second embodiment.
[0037] FIG. 3I is a process view showing the manufacturing method
of the second embodiment.
[0038] FIG. 3J is a process view showing the manufacturing method
of the second embodiment.
[0039] FIG. 3K is a process view showing the manufacturing method
of the second embodiment.
[0040] FIG. 3L is a process view showing the manufacturing method
of the second embodiment.
[0041] FIG. 3M is a process view showing the manufacturing method
of the second embodiment.
[0042] FIG. 3N is a process view showing the manufacturing method
of the second embodiment.
[0043] FIG. 3O is a process view showing the manufacturing method
of the second embodiment.
[0044] FIG. 3P is a process view showing the manufacturing method
of the second embodiment.
[0045] FIG. 3Q is a process view showing the manufacturing method
of the second embodiment.
[0046] FIG. 4A is a view showing a drive status of the transistor
of the second embodiment.
[0047] FIG. 4B is a view showing a drive status of the transistor
of the second embodiment.
[0048] FIG. 5 is a schematic cross-sectional view of a transistor
of a third embodiment.
[0049] FIG. 6A is a process view showing a manufacturing method of
the third embodiment.
[0050] FIG. 6B is a process view showing the manufacturing method
of the third embodiment.
[0051] FIG. 6C is a process view showing the manufacturing method
of the third embodiment.
[0052] FIG. 6D is a process view showing the manufacturing method
of the third embodiment.
[0053] FIG. 6E is a process view showing the manufacturing method
of the third embodiment.
[0054] FIG. 6F is a process view showing the manufacturing method
of the third embodiment.
[0055] FIG. 6G is a process view showing the manufacturing method
of the third embodiment.
[0056] FIG. 7 shows photographs showing the results of Example
1.
[0057] FIG. 8A is a view showing a manufacturing process of a
sandwich cell evaluated in Example 2.
[0058] FIG. 8B is a view showing the manufacturing process of the
sandwich cell evaluated in Example 2.
[0059] FIG. 8C is a view showing the manufacturing process of the
sandwich cell evaluated in Example 2.
[0060] FIG. 9 is a graph showing the frequency dependence of
dielectric constant of an insulator layer of Example 2.
[0061] FIG. 10 is a graph showing an evaluation result of
insulating property of the insulator layer of Example 2.
[0062] FIG. 11 shows photographs showing the results of Example
3.
[0063] FIG. 12 shows photographs showing the results of Example
3.
[0064] FIG. 13 shows photographs showing the results of Example
3.
[0065] FIG. 14 shows a photograph showing the result of Example
3.
[0066] FIG. 15 shows a graph showing the result of Example 3.
DESCRIPTION OF THE EMBODIMENTS
First Embodiment
[0067] Hereinafter, a first embodiment of the present invention
will be described.
[0068] (Composition)
[0069] A composition of the present embodiment includes the
following (a) to (c):
[0070] (a) an organic compound having a hydroxy group;
[0071] (b) a first cross-linking agent that is at least one organic
silicon compound selected from the group including [0072] (b-1) an
organic silicon compound including a siloxane bond in the molecule
and having three or more cyclic ether groups in the molecule,
[0073] (b-2) a chain organic silicon compound including two or more
siloxane bonds in the molecule and having two or more cyclic ether
groups in the molecule, [0074] (b-3) a cyclic organic silicon
compound including a siloxane unit (D unit) represented by
R.sup.1R.sup.2SiO.sub.2/2 in the molecule, any one of or both of
R.sup.1 and R.sup.2 being a cyclic ether group, and having four or
more cyclic ether groups bonded to a silicon atom of the D unit in
the molecule, and [0075] (b-4) a cyclic organic silicon compound
including a siloxane unit (T unit) represented by
R.sup.3SiO.sub.3/2 in the molecule, R.sup.3 being a cyclic ether
group, and having two or more cyclic ether groups in the molecule;
and
[0076] (c) a photocationic polymerization initiator.
[0077] Hereinafter, there will be described a case that the
composition is a curable composition, but the composition of the
present invention is not limited to the curable composition.
[0078] The curable composition of the present embodiment is soluble
in an alkaline solution. As an alkaline solution, an alkaline
developer which is commonly used in a field such as
photolithography can be used. Examples of materials of the
developer include an aqueous TMAH (tetramethylammonium hydroxide)
solution and an aqueous NaOH (sodium hydroxide) solution.
[0079] Note that, the term "soluble in an alkaline solution" refers
to that when a coating film formed in a film thickness of 1 .mu.m
is immersed in 2.38 mass % of an aqueous TMAH (tetramethylammonium
hydroxide) at 25.degree. C. for 2 minutes, the immersed portion of
the coating film is completely dissolved and removed.
[0080] Further, the term "coating film completely dissolved" refers
to that when the aqueous TMAH solution after the test is filtered
by a membrane filter (pore size 0.1 .mu.m), a solid form of the
coating film is not visually confirmed on the membrane filter.
[0081] Further, the "cyclic ether group" refers to a group obtained
by removing one hydrogen atom included in the cyclic ether. The one
hydrogen atom to be removed may be an atom connected directly to
the ring structure of the cyclic ether or may be an atom included
in a substituent connected to the ring structure.
[0082] Further, the "siloxane bond" refers to a Si--O--Si bond, and
the number of siloxane bonds refers to the number of oxygen atoms
that constitute the siloxane bond. For example, in the case of the
structure of Si--O--Si--O--Si, the number of siloxane bonds is
2.
[0083] Further, the "chain organic silicon compound" refers to an
organic silicon compound in which the skeleton having the siloxane
bond is chainlike.
[0084] Further, the "cyclic organic silicon compound" refers to an
organic silicon compound in which the skeleton having a siloxane
unit (D unit) represented by R.sup.1R.sup.2SiO.sub.2/2 or a
siloxane unit (T unit) represented by R.sup.3SiO.sub.3/2
constitutes the ring structure. The term "cyclic" includes
"monocyclic", "polycyclic", "cross-linked structure", and
"spirocyclic structure".
[0085] Hereinafter, a compound that constitutes a curable
composition used in the method of manufacturing a laminate of the
present embodiment will be described. It is determined whether the
compound that constitutes the curable composition in the present
specification is usable or unusable, not based on whether or not an
individual compound is "soluble in an alkaline solution", but based
on whether or not a curable composition constituted by the
individual compound is "soluble in an alkaline solution".
[0086] As the organic compound (a), a commonly known organic
compound can be used as long as the organic compound has an
insulation property. When a high dielectric property in addition to
the insulation property is required, for example, in a case where
an insulator layer formed by using the curable composition is used
for a gate insulator film of a transistor or a condenser, the
organic compound (a) can include a phenolic hydroxy group. Examples
of such an organic compound include polyvinyl phenol (PVP), and
poly(2-hydroxyethyl methacrylate). Specifically, polyvinyl phenol
(436224, manufactured by Sigma-Aldrich Corporation), and
poly(2-hydroxyethyl methacrylate) (529265, manufactured by
Sigma-Aldrich Corporation) can be used.
[0087] The cyclic ether group included in the first cross-linking
agent (b) may be a group that has a ring opened by a cation under a
cationic polymerization environment and that is bondable to the
organic compound (a). Examples of such a group include a 3 to
4-membered oxa cycloalkyl group, or a group having such an oxa
cycloalkyl group. The oxa cycloalkyl group may include a condensed
ring structure.
[0088] Such an oxa cycloalkyl group can be a group having an epoxy
ring as a three-membered ring or a group having an oxetanyl ring as
a four-membered ring. Since the epoxy ring and the oxetanyl ring
have strain in the ring structure, the epoxy ring and the oxetanyl
ring have a high reactivity, and the ring is easily opened.
Therefore, the epoxy ring and the oxetanyl ring are capable of
forming a bond to the organic compound (a).
[0089] Examples of the cyclic ether group included in the first
cross-linking agent (b) include: (1) a 3 to 4-membered oxa
cycloalkyl group; (2) a group formed by substituting a 3 to
4-membered oxa cycloalkyl group for a hydrogen atom included in one
group selected from the group including: a straight-chain,
branched, or cyclic alkyl group of 1 to 20 carbon atoms; an
alkoxyalkyl group formed by substituting a straight-chain,
branched, or cyclic alkoxy group of 1 to 10 carbon atoms for a
hydrogen atom included in a straight-chain, branched, or cyclic
alkyl group of 1 to 10 carbon atoms; and an aromatic group; and (3)
a condensed ring group of a 3 to 4-membered oxa cycloalkyl group
and one selected from the group including: a straight-chain,
branched, or cyclic alkyl group of 1 to 20 carbon atoms; an
alkoxyalkyl group formed by substituting a straight-chain,
branched, or cyclic alkoxy group of 1 to 10 carbon atoms for a
hydrogen atom included in a straight-chain, branched, or cyclic
alkyl group of 1 to 10 carbon atoms; and an aromatic group.
[0090] In the organic silicon compound (b-1) including a siloxane
bond in the molecule and having three or more cyclic ether groups
in the molecule, the cyclic ether groups may be identical to each
other or may be different from each other.
[0091] In the chain organic silicon compound (b-2) including two or
more siloxane bonds in the molecule and having two or more cyclic
ether groups in the molecule, the cyclic ether groups may be
identical to each other or may be different from each other.
Further, in the chain organic silicon compound (b-2), the two or
more siloxane bonds may be in a straight chain form or may have a
branched structure.
[0092] Specific examples of such a chain organic silicon compound
(b-2) can include a compound represented by Formula (B21) below,
and a compound (Tris(glycidoxypropyldimethylsiloxy)phenylsilane
(SIT8715.6, manufactured by Gelest Inc.) represented by Formula
(B22) below.
##STR00001##
[0093] In the cyclic organic silicon compound (b-3) including a
siloxane unit (D unit) represented by R.sup.1R.sup.2SiO.sub.2/2 in
the molecule, any one of or both of R.sup.1 and R.sup.2 being a
cyclic ether group, and having four or more cyclic ether groups
bonded to a silicon atom of the D unit in the molecule, the cyclic
ether groups may be identical to each other or may be different
from each other. Further, in a case where a plurality of D units
are included, R.sup.1s included in the D units may be identical to
each other or may be different from each other, and R.sup.2s
included in the D units may be identical to each other or may be
different from each other.
[0094] In the cyclic organic silicon compound (b-3), the D units
may be bonded to each other to form a monocyclic structure
surrounded by a Si--O--Si bond, or may further include a siloxane
unit of a T unit that does not have a cyclic ether group to thereby
form a cage-shaped structure surrounded by a Si--O--Si bond.
Further, in a case where the T unit is included, the cyclic organic
silicon compound (b-3) may have a structure in which a silicon atom
is not bonded to the other end of an oxygen atom that constitutes a
Si--O bond and part of the cage-shaped structure is not surrounded
by a Si--O--Si bond.
[0095] In the cyclic organic silicon compound (b-4) including a
siloxane unit (T unit) represented by R.sup.3SiO.sub.3/2 in the
molecule, R.sup.3 being a cyclic ether group, and having two or
more cyclic ether groups in the molecule, the cyclic ether groups
may be identical to each other or may be different from each other.
Further, in a case where a plurality of T units are included,
R.sup.3s included in the T units may be identical to each other or
may be different from each other.
[0096] In the cyclic organic silicon compound (b-4), the T units
may be bonded to each other to form a cage-shaped structure
surrounded by a Si--O--Si bond, or in an unit structure of part of
T units, a structure may be formed in which a silicon atom is not
bonded to the other end of an oxygen atom that constitutes a Si--O
bond and part of the cage-shaped structure is not surrounded by a
Si--O--Si bond. Further, the cyclic organic silicon compound (b-4)
may include a siloxane unit of a D unit.
[0097] A specific example of such a cyclic organic silicon compound
(b-4) can include a compound
(PSS-Octa[(3-glycidyloxypropyl)dimethylsiloxy]substituted (593869,
manufactured by Sigma-Aldrich Corporation)) represented by Formula
(B41) below.
##STR00002##
[0098] As the first cross-linking agent (b), a cyclic organic
silicon compound (b-3) or (b-4) in which Si--O bonds are aggregated
is preferably used.
[0099] The photocationic polymerization initiator (c) is a compound
that initiates the cationic polymerization reaction of a curable
composition using the cationic species or Lewis acid generated by
the absorption of light (for example, ultraviolet light) energy. As
the photocationic polymerization initiator, known photocationic
polymerization initiators, such as aromatic diazonium salts,
aromatic sulfonium salts, aromatic iodonium salts, metallocene
compounds, phosphonium salts, and silanol-aluminum complexes, can
be used. These compounds may be used alone or in a mixture of two
or more.
[0100] A specific example of the photocationic polymerization
initiator (c) may include OMPH076 manufactured by Glest Inc., which
is an aromatic sulfonium salt.
[0101] Here, in order to increase the reactivity of the
photocationic polymerization initiator (c), a photosensitizer that
accelerates the reaction of the photocationic polymerization
initiator (c) by absorbing light and transferring the absorbed
energy to the photocationic polymerization initiator (c) may be
added to the curable composition.
[0102] The curable composition of the present embodiment may
further include a second cross-linking agent (d) that is an organic
compound having two or more cyclic ether groups. When the curable
composition further includes the second cross-linking agent, it is
possible to add physical properties due to the second cross-linking
agent to an insulator, which will be formed, and the degree of
freedom of design is enhanced.
[0103] For example, in order to improve insulation properties of
the insulator to be formed and additionally improve the dielectric
constant, the second cross-linking agent can be a compound having
an aromatic ring and is preferably a compound represented by
Formula (d1) below.
##STR00003##
[0104] (R.sup.2 and R.sup.3 are each a cyclic ether group. R.sup.2
and R.sup.3 may be identical to each other or may be different from
each other.)
[0105] The cyclic ether group represented as R.sup.2 and R.sup.3
can be a group formed by substituting a 3 to 4-membered oxa
cycloalkyl group for a hydrogen atom included in one selected from
the group including: a straight-chain, branched, or cyclic alkyl
group of 1 to 20 carbon atoms; an alkoxyalkyl group formed by
substituting a straight-chain, branched, or cyclic alkoxy group of
1 to 10 carbon atoms for a hydrogen atom included in a
straight-chain, branched, or cyclic alkyl group of 1 to 10 carbon
atoms; and an aromatic group.
[0106] The oxa cycloalkyl group included in the group represented
as R.sup.2 and R.sup.3 can be a group having an epoxy ring that is
a three-membered ring or a group having an oxetanyl ring that is a
four-membered ring. Since the epoxy ring and the oxetanyl ring have
strain in the ring structure, the epoxy ring and the oxetanyl ring
have a high reactivity, and the ring is easily opened such that a
cationic polymerization reaction occurs.
[0107] A specific example of the second cross-linking agent (d) can
include a bisphenol A epoxy monomer (RE310S, manufactured by Nippon
Kayaku Co., Ltd.) represented by Formula (d2) below.
##STR00004##
[0108] In the curable composition of the present embodiment, the
ratio of the sum of the mass of the first cross-linking agent (b)
and the second cross-linking agent (d) to the total sum of the mass
of the organic compound (a) having a hydroxy group, the first
cross-linking agent (b), and the second cross-linking agent (d) can
be 40 mass % to 90 mass %, and the ratio of the mass of the second
cross-linking agent (d) to the total sum of (a), (b) and (d) can be
5 mass % to 30 mass %. Although most of second cross-linking agents
(d) are insoluble in an alkaline solution, when such a combination
is used, it is possible to add physical properties due to the
second cross-linking agent to the insulator in a state where the
entire curable composition is soluble in an alkaline solution.
[0109] The curable composition of the present embodiment may be
used in combination with various fillers within a range that does
not impair the advantages of the present invention. When the
curable composition is used in combination with a filler, the
curable composition functions as the binder of the filler, and
physical properties due to the filler can be further imparted to an
insulator, which will be formed.
[0110] Although most of such fillers are insoluble in an alkaline
solution, when a coating film of a curable composition including a
filler is immersed in an alkaline solution, the curable composition
is dissolved in the alkaline solution. Thereby, the support of the
filler is lost, and the filler is dispersed in the alkaline
solution. Accordingly, it is possible to remove even a composition
using a curable composition with a filler by the alkaline
solution.
[0111] The curable composition as described above is developable by
an alkaline solution and is capable of forming an insulator layer.
Therefore, it is possible to reduce a manufacturing load.
[0112] (Manufacturing Method of Laminate, Laminate)
[0113] Hereinafter, a method of manufacturing a laminate according
to the present embodiment and a laminate will be described with
reference to FIGS. 1A to 1C. In all the following drawings, for
ease of understanding the drawings, dimensions, proportions, and
the like of each component are appropriately varied.
[0114] FIGS. 1A to 1C are process views showing a method of
manufacturing a laminate according to the present embodiment.
[0115] First, as shown in FIG. 1A, a solution in which the
aforementioned curable composition is dissolved in an organic
solvent (hereinafter, referred to as "a raw material solution") is
applied over a conductive layer 200 formed on a substrate 100, and
the solvent is removed. Thereby, a coating film 300 is formed.
[0116] Examples of the formation material of the substrate 100 may
include: inorganic materials, such as glass, quartz glass, and
silicon nitride; and organic materials (resin materials), such as
acrylic resins, polycarbonate resins, polyester resins such as
polyethylene terephthalate (PET) and polybutylene terephthalate
(PBT).
[0117] As the conductive layer 200, wirings and electrodes can be
exemplified. Examples of the formation material of the conductive
layer 200 may include conductive polymers, metals such as Al, Ag
and Au, and alloys. Generally known formation materials can be used
in addition to these formation materials.
[0118] The coating film 300 is formed by applying the raw material
solution and then removing the solvent. As the method of applying
the raw material solution, generally known methods, such as spin
coating, dip coating, spray coating, roll coating, brushing,
flexographic printing, inkjet printing, and screen printing, may be
exemplified.
[0119] In addition, as the solvent dissolving the curable
composition, various organic solvents can be used. Examples of the
organic solvent may include: alcohols, such as methanol, ethanol,
1-propanol, and 2-propanol (isopropyl alcohol (IPA)); ethers, such
as propylene glycol monomethyl ether acetate (PGMEA); aromatic
hydrocarbons, such as toluene and xylene; nitriles such as
acetonitrile; esters such as acetic acid ester; ketones, such as
acetone, methyl ethyl ketone, methyl isobutyl ketone, and
cyclohexanone. These organic solvents may be used alone or in a
mixture of two or more.
[0120] In order to remove a solvent from the applied raw material
solution, a method of volatilizing the solvent using generally
known operations such as heating, air blow and depressurization can
be used. These operations may be used in a combination of two or
more. In addition, the film obtained by removing a solvent from the
raw material solution is prebaked. Thereby, the non-patterned
coating film 300 is formed. The prebaking is performed, for
example, by heating the film obtained by removing a solvent from
the raw material solution at 105.degree. C. for 5 minutes.
[0121] Next, as shown in FIG. 1B, the coating film 300 is
irradiated with ultraviolet L (light) through a mask M provided
with an opening Ma in a region overlapping the conductive layer 200
in a plan view and having a light shielding portion Mb around the
opening Ma, so as to allow the coating film 300 to be exposed to
light. The ultraviolet L is light having an absorption wavelength
of the photocationic polymerization initiator included in the
curable composition. For example, in the mask exposure of the
present embodiment, ultraviolet of i-line ray (365 nm) is
irradiated at an irradiation intensity of 500 mJ/cm.sup.2.
Accordingly, a photocationic polymerization reaction proceeds in
the coating film 300, and the latent image of an insulator layer
310 is formed on the coating film 300.
[0122] Here, in order to accelerate a curing reaction by
photocationic polymerization, a heat treatment may be performed in
a temperature range of 100.degree. C. to 120.degree. C. for 10
minutes. This heat treatment may be performed simultaneously with
the irradiation of ultraviolet L and may also be performed after
the irradiation of ultraviolet L.
[0123] Next, as shown in FIG. 1C, the coating film 300 subjected to
mask exposure as shown in FIG. 1B is developed using an alkaline
solution as a developer S. As the developer S, for example, 2.38
mass % of an aqueous TMAH solution can be used, and the developing
time, for example, may be set to 1 minute.
[0124] The solubility of the exposed region (insulator layer 310)
of the coating film 300 in the developer S relatively decreases
compared to that of the non-exposed region in the coating film 300,
because photocationic polymerization proceeds and the molecular
weight increases. Therefore, the non-exposed region of the coating
film 300 is dissolved and developed by the developer S, and thereby
it is possible to form a laminate 1000 having the insulator layer
310 covering the conductive layer 200.
[0125] Prior to applying a raw material solution shown in FIG. 1A,
a surface treatment may be applied on at least a region in which
the insulator layer 310 will be formed by using a silane coupling
agent (first silane coupling agent) having a cyclic ether group. A
specific example of such a silane coupling agent includes
3-glycidoxypropyl triethoxysilane (KBM-403, manufactured by
Shin-Etsu Silicone Co., Ltd.). When such a silane coupling agent is
applied in advance and a surface treatment is performed, the cyclic
ether group included in the silane coupling agent reacts and bonds
to an organic compound included in the curable composition during a
photocationic polymerization reaction. Therefore, an adhesion power
between the insulator layer 310 to be formed and the substrate 100
and an adhesion power between the insulator layer 310 to be formed
and the conductive layer 200 are enhanced, and it is possible to
suppress damage to the laminate 1000.
[0126] The method of manufacturing a laminate as described above
uses a curable composition that is developable by an alkaline
solution and is capable of forming an insulator layer. Therefore,
it is possible to provide a manufacturing process in which a
manufacturing load is reduced.
[0127] The laminate as described above uses a curable composition
that is developable by an alkaline solution and is capable of
forming an insulator layer. Therefore, even when a resin substrate
is used, it is possible to preventing the substrate from being
dissolved or swelled.
[0128] As the laminate 1000 having a laminated structure
manufactured in this way, a wiring board, a condenser, and the
like, each having a multi-layer interconnect structure, are
exemplified.
Second embodiment
Manufacturing Method of Transistor, Transistor
[0129] Next, a method of manufacturing a transistor according to a
second embodiment of the present invention and a transistor will be
described with reference to FIGS. 2 to 4B.
[0130] FIG. 2 is a schematic cross-sectional view showing a
transistor manufactured by the method of manufacturing a transistor
according to the present embodiment, and a transistor according to
the present embodiment. A transistor 1A is a so-called
bottom-contact type transistor. In the following description, there
will be described an organic transistor using an organic
semiconductor as the formation material of a semiconductor layer,
but the present invention is also applicable to an inorganic
transistor using an inorganic semiconductor as the formation
material of a semiconductor layer.
[0131] The transistor 1A includes a substrate 2, base films 3 and
13, electroless plating catalysts 5 and 15, a gate electrode 6, an
insulator layer 7, a source electrode 16, a drain electrode 17, and
an organic semiconductor layer (semiconductor layer) 20. In the
transistor 1A, the layer of a combination of the insulator layer 7
and the base film 13 refers to "a layer containing an insulator
layer".
[0132] As the substrate 2, any of a substrate having optical
transparency and a substrate not having optical transparency can be
used. For example, the substrate 2 can be made of any one of:
inorganic materials such as glass, quartz glass, and silicon
nitride; and organic polymers (resins), such as acrylic resins,
polycarbonate resins, and polyester resins (for example,
polyethylene terephthalate (PET), polybutylene terephthalate (PBT),
and the like).
[0133] The formation material of these substrates 2 does not form a
metallic bond together with a metal-made plating film formed as a
result of electroless plating. For this reason, in the present
embodiment, the formation material of these substrates 2 is treated
as a poor plating material on which a plating film is not easily
formed directly, and the formed plating film is easily stripped.
Due to the similar reason, if the plating film is made of an
easily-strippable material, for example, a composite material of
the above-mentioned material and the like can also be similarly
used as the formation material of the substrate 2.
[0134] The base film 3 is a gate base film in the present
invention. The base film 3 is formed over the entire surface of the
main side of the substrate 2, and part of the surface of the base
film 3 is selectively provided with a catalyst (electroless plating
catalyst) 5. The catalyst 5 is a catalyst for reducing metal ions
contained in a plating solution for electroless plating. As the
catalyst, silver, metal palladium, and the like are exemplified. In
the present embodiment, metal palladium is used.
[0135] The base film 3 is a film capable of capturing a metal that
is the above-mentioned catalyst 5, and a silane coupling agent
(second silane coupling agent) having a group capable of capturing
the metal is used as the formation material of the base film 3. The
base film 3 is formed by applying a liquid product containing such
a silane coupling agent onto the main side of the substrate 2.
[0136] The "silane coupling agent", which is the formational
material of the base film 3, is a compound in which a group capable
of capturing the metal (catalyst 5) and a group capable of being
bonded to the substrate 2 are bonded to a silicon atom.
[0137] Here, the "group capable of capturing the metal" refers to a
group that can capture the metal (catalyst 5) or ions of this
metal, for example, by an ion bond or a coordinate bond. As this
group, a group having a nitrogen atom or a sulfur atom is
exemplified. Examples of the group having a nitrogen atom or a
sulfur atom may include an amino group, a urea group, a thiol group
(or a mercapto group), a thiocarbonyl group, a thiourea group, and
a group obtained by removing one or more hydrogen atoms bonded to a
heterocyclic compound containing a nitrogen atom or a sulfur atom.
Examples of the "heterocyclic compound containing a nitrogen atom
or a sulfur atom" include: monocyclic aromatic heterocyclic
compounds, such as pyrrole, imidazole, pyridine, pyrimidine, and
thiophene; polycyclic aromatic heterocyclic compounds, such as
indole and benzothiophene; and non-aromatic heterocyclic compounds
in which two or more carbon atoms in an aromatic ring of each of
these aromatic compounds are hydrogenated.
[0138] As the "group capable of being bonded to the substrate 2", a
hydroxyl group and an alkoxy group of 1 to 6 carbon atoms are
exemplified.
[0139] Specific examples of the compound that can be used as the
formation material of the base film 3 may include
N-cyclohexyl-aminopropyltrimethoxysilane,
bis(3-(trimethoxysilyl)propyl)ethylenediamine,
1-(3-(trimethoxysilylpropyl))urea,
bis(3-trimethoxysilylpropyl))urea,
2,2-dimethoxy-1,6-diaza-2-silacyclooctane, N-(3-(trimethoxysilyl
propyl))-4,5-dihydroimidazole,
bis(3-(trimethoxysilyl)propyl)thiourea,
3-trimethoxysilylpropanethiol, and polyethyleneimine modified with
a trimethoxysilylpropyl group.
[0140] Among these, as the silane coupling agent, a silane coupling
agent having an amino group as the "group capable of capturing
metal" is preferable, and a silane coupling agent, which is a
primary amine or a secondary amine ("group capable of capturing
metal" is a group represented by --NH.sub.2 or --NH--), is more
preferable. In the following description, as the base film 3, a
base film formed by using a silane coupling agent as a primary
amine will be described.
[0141] The gate electrode 6 is a metal electrode formed on the
surface of the catalyst 5, and, as described later, is formed of a
metal deposited on the surface of the catalyst 5 by electroless
plating. As the material of the gate electrode 6, nickel phosphorus
(NiP) or copper (Cu) is exemplified.
[0142] The insulator layer 7 electrically insulates the gate
electrode 6 having insulating properties from the source electrode
16 and the drain electrode 17. In the insulator layer 7 of the
present embodiment, the above-mentioned curable composition in the
first embodiment is used as a formation material.
[0143] The base film 13 is formed on the entire upper surface of
the insulator layer 7. The base film 13 is a source base film and
is a drain base film in the present invention, and the source base
film and the drain base film are formed as a continuous film. The
base film 13 is formed over the entire surface of the main side of
the substrate 2, and part of the surface of the base film 13 is
selectively provided with a catalyst (catalyst for electroless
catalyst) 15. The formation material of the catalyst 15 may be the
same as that of the above-mentioned catalyst 5.
[0144] The formation material of the base film 13 is the same as
that of the above-mentioned base film 3, but the formation
materials of the base film 3 and the base film 13 may be different
from each other. In the following description, a case where the
base film 13 is formed by using a silane coupling agent as a
primary amine which is the same as that used for the base film 3
will be described.
[0145] In the drawing, it is shown that the base film 13 is formed
on the entire upper surface of the insulator layer 7, but the base
film 13 may be selectively formed on only a location where the
catalyst 15 is provided. In this case, a silane coupling agent,
which is a formation material of the base film 13, is selectively
applied to the upper surface of the insulator layer 7 using a
generally known method, and thereby it is possible to selectively
form the base film 13. Further, in the upper surface of the
insulator layer 7, first, the silane coupling agent may be applied
to a region larger than the region forming the base film 13, and
then a film formed at a portion protruding from the region forming
the base film 13 may be irradiated with ultraviolet to thereby
decompose and remove the silane coupling agent to selectively form
the base film 13.
[0146] The source electrode 16 and the drain electrode 17 are metal
electrodes formed on the surface of the catalyst 15. The source
electrode 16 has a first electrode 161 and a second electrode 162
covering the surface of the first electrode 161. Similarly, the
drain electrode 17 has a third electrode 171 and a fourth electrode
172 covering the surface of the third electrode 171.
[0147] The first electrode 161 and the third electrode 171,
similarly to the above-mentioned gate electrode 6, are formed by
electroless plating. As the material of each of the first electrode
161 and the third electrode 171, nickel phosphorus (NiP) or copper
(Cu) is exemplified. In the present embodiment, it is described
that nickel phosphorus (work function: 5.5 eV) is used as the
formation material of each of the first electrode 161 and the third
electrode 171. Here, the first electrode 161 and the third
electrode 171 may each be formed using a different material.
[0148] The second electrode 162 and the fourth electrode 172 are
metal plating layers, each being formed over the entire surface of
each of the first electrode 161 and the third electrode 171, the
surface not being in contact with the catalyst 15. That is, the
second electrode 162 is provided to cover a lateral side 16a in the
source electrode 16. The fourth electrode 172 is provided to cover
a lateral side 17a in the drain electrode 17. The lateral sides 16a
and 17a (opposing surfaces) face each other.
[0149] As the formation material of each of the second electrode
162 and the fourth electrode 172, a metal material having a work
function in which electron transfer (or hole transfer) is easy in
relation to the HOMO/LUMO level of the formation material of a
semiconductor layer 20 to be described later is used. In the
present embodiment, it is described that gold (work function: 5.4
eV) is used as the formation material of each of the second
electrode 162 and the fourth electrode 172. Here, the second
electrode 162 and the fourth electrode 172 may each be formed using
a different material.
[0150] The semiconductor layer 20 is provided on the surface of the
base film 13 between the source electrode 16 and the drain
electrode 17, and is formed in contact with the source electrode 16
and the drain electrode 17. Specifically, the semiconductor layer
20 is provided in contact with the lateral side 16a of the source
electrode 16 and the lateral side 17a of the drain electrode 17,
and is in contact with the second electrode 162 and the fourth
electrode 172.
[0151] As the formation material of the semiconductor layer 20,
generally known organic semiconductor materials can be used.
Examples of the semiconductor materials may include: p-type
semiconductors, such as copper phthalocyanine (CuPc), pentacene,
rubrene, tetracene, and P3HT (poly(3-hexylthiophene-2,5-diyl)); and
n-type semiconductors, such as fullerenes such as C.sub.60 and
perylene derivatives such as PTCDI-C8H
(N,N'-dioctyl-3,4,9,10-perylene tetracarboxylic diimide). Among
these, soluble pentacene such as TIPS pentacene
(6,13-bis(triisopropylsilylethynyl)pentacene) or an organic
semiconductor polymer such as P3HT is soluble in an organic solvent
such as toluene and can be used in forming the semiconductor layer
20 by a wet process, which is preferable. In the present
embodiment, it will be described that TIPS pentacene (HOMO level:
5.2 eV), which is a p-type semiconductor, is used as the formation
material of the semiconductor layer 20.
[0152] Further, the formation material of the semiconductor layer
20 is not limited to organic semiconductor materials, and generally
known inorganic semiconductor materials can also be used as the
formation material of the semiconductor layer 20.
[0153] In this transistor 1A, the gate electrode 6, the source
electrode 16, and the drain electrode 17, which are formed by
electroless plating, are formed on the base films 3 and 13 (gate
base film, source base film, and drain base film), which are formed
by using a silane coupling agent as a formation material. For
example, when these electrodes are formed in the region having an
uneven shape, an uneven shape is imparted to each of these
electrodes in response to unevenness of a base. In this case, the
distance between the electrodes laminated through an insulator
layer is not constant, and there is a possibility that the
insulation is damaged and leak current is generated at the position
where the distance between the gate electrode and the source
electrode or the distance between the gate electrode and the drain
electrode becomes closer to each other. Further, if the base has an
uneven shape, there is a possibility that an uneven shape is
imparted even to the channel region (represented by AR in FIG. 2)
of the semiconductor layer overlapping the gate electrode in a plan
view, and the migration distance of a carrier in the channel region
becomes longer, thereby deteriorating the performance of the
transistor 1A.
[0154] However, in the transistor 1A of the present embodiment,
since the base films 3 and 13 are formed by using a silane coupling
agent as a formation material and a base film containing a filler
component capable of roughening the surface of the substrate is not
used, these base films become smooth films. Therefore, uneven
shapes are not formed by forming the base films 3 and 13, and the
problems caused by the uneven shapes do not occur, and therefore
the transistor 1A becomes a high-performance transistor.
[0155] Hereinafter, the method of manufacturing the above-mentioned
transistor 1A will be described with reference to FIGS. 3A to
3Q.
[0156] First, as shown in FIG. 3A, a liquid product, which is
obtained, if necessary, by diluting the above-mentioned silane
coupling agent with an organic solvent, is applied onto the surface
of a substrate 2 to form a coating film 3A. As the method of
applying the liquid product, generally known methods, such as spin
coating, dip coating, spray coating, roll coating, brushing,
flexographic printing, and screen printing, may be exemplified.
[0157] Here, it will be described that
3-aminopropyltriethoxysilane, which is a primary amine, is used as
the silane coupling agent.
[0158] As the organic solvent, various organic solvents can be used
as long as the solvents are capable of dissolving the silane
coupling agent. Among these organic solvents, a polar solvent can
be preferably used. Examples of the solvent that can be used may
include: alcohols, such as methanol, ethanol, 1-propanol, and
2-propanol (isopropyl alcohol (IPA)); ethers, such as propylene
glycol monomethyl ether acetate (PGMEA); aromatic hydrocarbons,
such as toluene; nitriles such as acetonitrile; esters such as
acetic acid ester; and ketones, such as acetone, methyl ethyl
ketone, and methyl isobutyl ketone.
[0159] Next, as shown in FIG. 3B, the organic solvent is
volatilized and removed by a heat treatment to form a base film 3.
The base film 3 formed in this manner is a silane coupling agent
layer having an extremely thin film thickness, and therefore
becomes a transparent film in which light scattering does not
easily occur. Therefore, for example, if the transistor
manufactured by the method of the present embodiment is provided on
a substrate having optical transparency, it is possible to maintain
the optical transparency as a combination of the substrate 2 and
the base film 3 even when the base film 3 is formed on the entire
surface of the substrate 2, and it is possible to easily form the
film.
[0160] Next, as shown in FIG. 3C, a resist material is applied onto
the base film 3, and is then prebaked to thereby form a resist
layer 4A that is not patterned. Here, as the resist material, a
positive photoresist is used.
[0161] Thereafter, the resist layer 4A is irradiated with
ultraviolet L through a mask M1 including an opening Ma provided at
the position corresponding to the region forming a metal electrode
and including a light shielding portion Mb provided in the region
not forming the metal electrode, so as to expose the resist layer
4A to light.
[0162] Next, as shown in FIG. 3D, the resist layer irradiated with
ultraviolet is developed by a developer that dissolves the resist
layer to thereby form a resist layer 4 provided with an opening
4a.
[0163] Next, as shown in FIG. 3E, a catalyst 5 used in electroless
plating is captured on the surface of the base film 3 exposed
through the opening 4a formed in the resist layer 4. Specifically,
a metal, which is the catalyst 5, is captured on the base film 3 by
contacting a colloidal solution of a divalent palladium salt.
[0164] A general electroless plating process of a resin proceeds in
the order of washing, etching, catalyst imparting, and then
electroless plating. Here, the "catalyst imparting" is a process of
attaching a metal such as palladium (Pd), serving as an electroless
plating reaction initiator (catalyst), to the surface of the region
for carrying out plating. Generally, the "catalyst imparting"
includes a process of bringing a colloidal solution of a divalent
palladium salt and a divalent tin (Sn) salt into contact with a
substrate to be attached by palladium and then immersing the
substrate coated with the colloidal solution into an acid or alkali
solution, called an accelerator. Thereby, the divalent palladium is
reduced to zero-valent palladium, and the catalyst is
activated.
[0165] In contrast, as described in the present embodiment, it was
confirmed by the inventors that, if the silane coupling agent,
which is a formation material of a base film, is a primary amine or
a secondary amine, the reduction treatment using the
above-mentioned accelerator is not required (which will be
described later). Therefore, when a primary amine or a secondary
amine is used as the silane coupling agent, the operation of
electroless plating is simplified.
[0166] In the present embodiment, since
3-aminopropyltriethoxysilane, which is a primary amine, is used as
the formation material of the base film 3, a reduction treatment is
not required, and the operation is simplified.
[0167] On the other hand, when the silane coupling agent is a
tertiary amine or a silicon compound having another "group capable
of capturing a metal", a colloidal solution of a divalent palladium
salt is applied, and then a normal treatment (activating process)
using the above-mentioned accelerator is performed. Thereby, it is
possible to capture a catalyst 5 for electroless plating on the
base film 3.
[0168] Next, as shown in FIG. 3F, an electroless plating solution
is brought into contact with the catalyst 5. Thereby, metal ions
dissolved in the electroless plating solution is reduced and
deposited on the surface of the catalyst 5, and a gate electrode 6
containing nickel phosphorus as a formation material is selectively
formed in the opening 4a. When the silane coupling agent is a
primary amine or a secondary amine, the catalyst 5 is immersed in
the electroless plating solution without performing the activation
using the accelerator, and thereby the surface of the catalyst 5 is
plated. Therefore, it can be indirectly confirmed that metal
palladium is captured on the surface of the base film 3.
[0169] Next, as shown in FIG. 3G, the entire surface of the
remaining resist layer is exposed to ultraviolet, and then the
resist layer is removed by a generally known developer. In this
way, the gate electrode 6 is formed.
[0170] Next, as shown in FIG. 3H, a solution (raw material
solution), in which the curable composition of the first embodiment
is dissolved in an organic solvent, is applied to the surface of
the base film 3 to cover the gate electrode 6. As the application
method, the above-mentioned method can be used.
[0171] As the organic solvent, a material which is the same as that
described in the first embodiment can be used.
[0172] Further, in the raw material solution, when concentration
and the kind of an organic solvent are changed, the viscosity of
the entire raw material solution can be adjusted, and the thickness
of the coating film 7A of the raw material solution can be
controlled.
[0173] In the process shown in FIG. 3H, in order to control the
leak between the gate electrode 6 and the source electrode to be
formed above and the leak between the gate electrode 6 and the
drain electrode to be formed above, the photoresist is thickly
applied such that the thickness of the coating film 7A is about
several hundreds of nanometers. Here, the thickness of the coating
film 7A is not limited thereto.
[0174] Next, as shown in FIG. 3I, the coating film 7A is irradiated
with ultraviolet L through a mask M2 provided with an opening
corresponding to the region forming an insulator layer 7 to cure
the curable composition, thereby forming the insulator layer 7. In
this case, in order to accelerate the curing reaction of the
curable composition, a heat treatment can be performed
simultaneously with the ultraviolet irradiation or after the
ultraviolet irradiation.
[0175] Next, as shown in FIG. 3J, the coating film 7A is developed
by an alkaline solution (developer S) that dissolves the coating
film 7A to thereby remove the uncured coating film and form an
insulator layer 7 that is patterned.
[0176] Here, in order to improve the adhesiveness between the
insulator layer 7 and the gate electrode 6, the silane coupling
agent may be applied to cover the surface including the gate
electrode 6 before the application of the raw material
solution.
[0177] Next, as shown in FIG. 3K, a liquid product, which is
obtained, if necessary, by diluting the above-mentioned silane
coupling agent with an organic solvent, is applied onto the entire
upper surface of the insulator layer 7, and then a heat treatment
is performed to volatilize and remove the organic solvent, so as to
form a base film 13. The silane coupling agent and the organic
solvent may be the same as those used in the formation of the base
film 3 described above.
[0178] Next, as shown in FIG. 3L, a resist material is applied over
the insulator layer 7 and the base film 13 and is then prebaked.
Thereby, a resist layer 14A that is not patterned is formed. Here,
as the resist material, a positive photoresist is used.
[0179] Thereafter, the resist layer 14A is irradiated with
ultraviolet L through a mask M3 provided with an opening
corresponding to the region forming a source electrode and a drain
electrode, so as to expose the resist layer 14A to light.
[0180] Next, as shown in FIG. 3M, the resist layer irradiated with
ultraviolet is developed by a developer that dissolves the resist
layer to thereby form a resist layer 14 provided with an opening
14a.
[0181] Next, as shown in FIG. 3N, a colloidal solution of a
divalent palladium salt is made to come into contact with the base
film 13 exposed through the opening 14a. Thereby, the catalyst 15
used in electroless plating is captured to the surface of the base
film 13. Thereafter, an electroless plating solution is made to
come into contact with the catalyst 15. Thereby, metal ions
dissolved in the electroless plating solution are reduced and
deposited on the surface of the catalyst 15, and a first electrode
161 and a third electrode 171 made of nickel phosphorus are
selectively formed in the opening 14a.
[0182] Next, as shown in FIG. 3O, the entire surface of the
remaining resist layer is exposed to ultraviolet, and then the
resist layer is removed by a generally known developer. In this
way, the first electrode 161 and the third electrode 171 are
formed.
[0183] Next, as shown in FIG. 3P, the entire body is immersed into
a gold plating bath for substitution to allow the surface of the
first electrode 161 and the third electrode 171 to be substituted
and deposited with gold, and is further immersed into a gold
plating bath for reduction to thereby form a second electrode 162
and a fourth electrode 172, which are plated with gold, on the
surface of the first electrode 161 and the third electrode 171. In
this way, a source electrode 16 and a drain electrode 17 are
formed.
[0184] Next, as shown in FIG. 3Q, a solution S1, in which an
organic semiconductor material soluble in an organic solvent, such
as TIPS pentacene, is dissolved in the organic solvent, is applied
between the source electrode 16 and the drain electrode 17, and is
dried to thereby form a semiconductor layer 20. Here, the
semiconductor layer 20 is formed by a wet method, but can also be
formed by a sublimation method, a transfer method, or the like.
[0185] In this way, it is possible to manufacture the transistor
1A.
[0186] Prior to applying a raw material solution shown in FIG. 3H,
a surface treatment may be applied on at least a region in which
the insulator layer 7 will be formed by using a silane coupling
agent having a cyclic ether group.
[0187] A specific example of such a silane coupling agent includes
3-glycidoxypropyl triethoxysilane (KBM-403, manufactured by
Shin-Etsu Silicone Co., Ltd.). When such a silane coupling agent is
applied in advance and a surface treatment is performed, the cyclic
ether group included in the silane coupling agent reacts and bonds
to an organic compound included in the curable composition during a
photocationic polymerization reaction. Therefore, an adhesion power
between the insulator layer 7 to be formed and the substrate 2
(base film 3) and an adhesion power between the insulator layer 7
to be formed and the gate electrode 6 are enhanced, and it is
possible to suppress damage to the transistor 1A.
[0188] In the method of manufacturing a transistor of the
configuration as described above, a curable composition that is
developable by an alkaline solution and is capable of forming an
insulator layer is used. Therefore, it is possible to provide a
manufacturing process in which a manufacturing load is reduced.
[0189] In the transistor as described above, the insulator layer 7
is formed by using a curable composition that is developable by an
alkaline solution. Therefore, even when a resin substrate is used,
it is possible to prevent the substrate from being dissolved or
swelled by a developer, and it is possible to form a transistor
with reduced degradation during manufacturing.
[0190] Further, since the base films 3 and 13 are formed by using a
silane coupling agent as a formation material and are smooth films,
problems caused by the uneven shapes of the base films do not
occur, and a high-performance transistor can be obtained.
[0191] Further, since the resist layer 14 is previously removed
before the formation of the second electrode 162 and the fourth
electrode 172, the second electrode 162 and the fourth electrode
172 can be surely formed even on the lateral side 16a of the source
electrode 16 and the lateral side 17a of the drain electrode 17.
Therefore, in the manufactured transistor 1A, electric current
easily flows between the semiconductor layer 20 and the source
electrode 16 (or between the semiconductor layer 20 and the drain
electrode 17) at the time of driving, and the transistor 1A can be
well driven.
[0192] Further, the first electrode 161 is covered with the second
electrode 162, and the third electrode 171 is covered with the
fourth electrode 172. Thereby, the temporal corrosion of the first
electrode 161 and the third electrode 171 is suppressed, and there
is also an advantage in that the performance of the transistor can
be stably maintained.
[0193] FIGS. 4A and 4B are schematic views showing the drive status
of a transistor. FIG. 4A is a view showing a transistor 1x which
has the same configuration as the transistor 1A except that the
transistor 1x does not have the second electrode. FIG. 4B is a view
showing the transistor 1A manufactured by the method of the present
embodiment.
[0194] Here, in the present embodiment, the phrase "energy level of
molecular orbital used in electron transfer in the formation
material of an organic semiconductor layer" refers to the energy
level of HOMO in the case where the organic semiconductor layer is
made of a p-type semiconductor, and refers to the energy level of
LUMO in the case where the organic semiconductor layer is made of
an n-type semiconductor.
[0195] First, as in the transistor 1x shown in FIG. 4A, when the
transistor 1x has a configuration which does not include the second
electrode, since the gap (energy level difference) between the
energy level of HOMO of the semiconductor layer 20 and the work
function of the first electrode 161 becomes large, Schottky barrier
occurs, and electric current hardly flows. Therefore, for example,
as shown by an arrow A in FIG. 4A, it is easy to form the flow of
electric current through the highly-resistant semiconductor layer
20, and it is difficult to secure a good conduction.
[0196] In contrast, as shown in FIG. 4B, in the transistor 1A, when
a voltage is applied to the gate electrode (not shown), a channel
region AR having a thickness of several nanometers (nm) is formed
in the semiconductor layer 20 around the interface between the
semiconductor layer 20 and the base film 13, enabling the
conduction between the source electrode 16 and the drain electrode
(not shown). In this case, the surface of the source electrode 16
is provided with the second electrode 162, which is formed using a
metal material having a work function (energy level difference with
HOMO of the semiconductor layer 20 is small) at which electron
transfer is easier between the second electrode 162 and the
formation material of the semiconductor layer 20 compared to
between the second electrode 162 and the first electrode 161, and
the Shottky barrier is reduced, so that electric current easily
flows into the channel region AR through the first electrode 161
and the second electrode 162. FIG. 4B shows the flow of electric
current using an arrow B. Therefore, it is possible to realize a
high-performance transistor 1A.
Third Embodiment
[0197] FIG. 5 is a schematic cross-sectional view of a transistor
1B, which is manufactured by the manufacturing method of a
transistor according to a third embodiment of the present
invention.
[0198] The transistor 1B of the present embodiment is partially in
common with the transistor 1A of the second embodiment. The
difference between the transistor 1A and the transistor 1B is that
the transistor of the second embodiment is a bottom contact
transistor, and the transistor 1B of the present embodiment is a
top contact transistor. Accordingly, in the present embodiment, the
same reference numerals for the components in common with the
second embodiment are used, and detailed description of the
components will be omitted.
[0199] The transistor 1B includes a semiconductor layer 20 disposed
on an insulator layer 7 and having a surface on which a source
electrode 16 and a drain electrode 17 are formed.
[0200] That is, a semiconductor layer 20 is formed on the entire
upper surface of an insulator layer 7, and a base film 13 is formed
on the entire upper surface of the semiconductor layer 20. In the
transistor 1B, the layer of a combination of the insulator layer 7,
the semiconductor layer 20, and the base film 13 refers to a "layer
containing an insulator layer".
[0201] A catalyst 15 is selectively provided on the upper surface
of the base film 13, and a source electrode 16 including a first
electrode 161 and a second electrode 162, and a drain electrode 17
including a third electrode 171 and a fourth electrode 172 are
formed on the upper surface. In the semiconductor layer 20, the
region located in the vicinity of the upper surface of the
semiconductor layer and sandwiched between the source electrode 16
and the drain electrode 17 becomes a channel region AR.
[0202] Hereinafter, the method of manufacturing the above-mentioned
transistor 1B will be described with reference to FIGS. 6A to
6G
[0203] In the manufacture of the transistor 1B, first, similarly to
the second embodiment, a base film 3, a catalyst 5, a gate
electrode 6, and an insulator layer 7 are laminated on the upper
surface of a substrate 2. Next, as shown in FIG. 6A, a solution S1
in which an organic semiconductor soluble in an organic solvent is
dissolved in the organic solvent is applied onto the insulator
layer 7, and then dried to thereby form the semiconductor layer
20.
[0204] Next, as shown in FIG. 6B, a liquid product, which is
obtained, if necessary, by diluting the above-mentioned silane
coupling agent with an organic solvent, is applied onto the entire
upper surface of the semiconductor layer 20, and then is
heat-treated to volatilize and remove the organic solvent, thereby
forming a base film 13.
[0205] Next, as shown in FIG. 6C, a resist material is applied over
the insulator layer 7, the semiconductor layer 20, and the base
film 13, and is then prebaked to thereby form a resist layer 14A
that is not patterned. Thereafter, the resist layer 14A is
irradiated with ultraviolet L through a mask M3 provided with an
opening corresponding to the region forming a source electrode and
a drain electrode, so as to expose the resist layer 14A to
light.
[0206] Next, as shown in FIG. 6D, the resist layer irradiated with
ultraviolet is developed by a developer dissolving the resist layer
to thereby form a resist layer 14 provided with an opening 14a.
[0207] Next, as shown in FIG. 6E, a colloidal solution of a
divalent palladium salt is made to come into contact with the base
film 13 exposed through the opening 14a, thereby capturing the
catalyst 15 used in electroless plating to the surface of the base
film 13. Thereafter, an electroless plating solution is made to
come into contact with the catalyst 15. Thereby, metal ions
dissolved in the electroless plating solution is reduced and
deposited on the surface of the catalyst 15, and a first electrode
161 and a third electrode 171 made of nickel phosphorus are formed
selectively in the opening 14a (first electroless plating).
[0208] Next, as shown in FIG. 6F, the entire surface of the
remaining resist layer is exposed to ultraviolet, and then the
resist layer is removed by a generally known developer. In this
way, the first electrode 161 and the third electrode 171 are
formed.
[0209] Next, as shown in FIG. 6G, the entire body is immersed into
a gold plating bath for substitution to allow the surface of the
first electrode 161 and the third electrode 171 to be substituted
and deposited with gold, and is further immersed into a gold
plating bath for reduction to thereby form a second electrode 162
and a fourth electrode 172, which are plated with gold, on the
surface of the first electrode 161 and the third electrode 171
(second electroless plating). In this way, a source electrode 16
and a drain electrode 17 are formed.
[0210] In this way, it is possible to manufacture the transistor
1B.
[0211] Also in the transistor 1B as described above, the insulator
layer 7 is formed by using a curable composition that is
developable by an alkaline solution. Therefore, even when a resin
substrate is used, it is possible to prevent the substrate from
being dissolved or swelled by a developer, and it is possible to
form a transistor with reduced degradation during
manufacturing.
[0212] Further, the base films 3 and 13 are formed by using a
silane coupling agent as a formation material, and are smooth
films. Therefore, problems caused by the uneven shapes of the base
films do not occur, and it is possible to easily manufacture a
high-performance transistor.
[0213] Further, in the source electrode 16 of the transistor 1B,
the second electrode 162 is formed using a metal material having a
work function (energy level difference with HOMO of the
semiconductor layer 20 is small) at which electron transfer is
easier between the formation material of the semiconductor layer 20
and the second electrode 162 compared to between the first
electrode 161 and the second electrode 162. In the drain electrode
17 of the transistor 1B, the fourth electrode 172 is formed using a
metal material having a work function (energy level difference with
HOMO of the semiconductor layer 20 is small) at which electron
transfer is easier between the formation material of the
semiconductor layer 20 and the fourth electrode 172 compared to
between the third electrode 171 and the fourth electrode 172. In
the enclosed position shown by a reference numeral a, electric
current easily flows into the channel region AR from the second
electrode 162 and the fourth electrode 172, and therefore it is
possible to realize a high-performance transistor 1B.
[0214] Further, since the first electrode 161 is covered with the
second electrode 162 and the third electrode 171 is covered with
the fourth electrode 172, the temporal corrosion of the first
electrode 161 and the third electrode 171 is suppressed, and there
is also an advantage in that the performance of the transistor can
be stably maintained.
[0215] The transistor of the present embodiment is configured such
that the semiconductor layer 20 is not in contact directly with the
source electrode 16 and the drain electrode 17 but is in contact
with the source electrode 16 and the drain electrode 17 through the
base film 13, but the base film 13 is formed in a very thin layer
having a thickness of several nanometers (nm). Therefore, the
effect of the base film 13 influencing transistor characteristics
is small, and electric current flows well between the semiconductor
layer 20 and the source electrode 16 and between the semiconductor
layer 20 and the drain electrode 17.
[0216] Heretofore, examples of embodiments of the present invention
have been described with reference to the accompanying drawing, but
the present invention is not limited to the examples. The shapes,
combination, and the like of the components described in the
above-mentioned examples are merely examples, and can be variously
modified based on design requirements and the like without
departing from the scope of the present invention.
[0217] For example, a substrate can be made of a non-metallic
material. A plurality of plating members in each of which a base
film is formed on a PET substrate (non-metallic substrate) are
prepared. The plating members are conveyed, and simultaneously a
transistor is manufactured using the above-mentioned manufacturing
method in the conveying process. Thereby, it is possible to form a
high-performance transistor on the PET substrate.
[0218] Moreover, in a roll to roll process, in which a plating
member in which a base film is formed on a long PET film having
flexibility, as a substrate, is rolled, the rolled plating member
is conveyed while unrolling, transistors are continuously
manufactured using the above-mentioned manufacturing method, and
then the manufactured transistors are rolled, it is possible to
form a transistor on the PET film.
[0219] Further, in the present embodiment, a base film is formed
using a silane coupling agent as a formation material, a catalyst
for electroless plating is captured on the base film, and then
electroless plating is performed, so as to form a gate electrode, a
source electrode and a drain electrode. However, these electrodes
may also be formed by forming any one or two electrodes of these
electrodes using the above-mentioned method and forming the
remaining electrodes using another method. For example, the gate
electrode may be formed using a generally known patterning method,
and the source electrode and drain electrode, which are formed in
the same layer, may be formed using the above-mentioned
manufacturing method.
EXAMPLES
[0220] Hereinafter, the present invention will be described in more
detail with reference to the following Examples, but the scope of
the present invention is not limited to these Examples.
Example 1
[0221] In Example 1, a solution of the following combination was
used for a raw material solution in which a curable composition is
dissolved.
[0222] (Raw Material Solution 1)
[0223] (a) organic compound having a hydroxy group: 4 mass % of
polyvinyl phenol (PVP) (436224, manufactured by Sigma-Aldrich
Corporation)
[0224] (b) first cross-linking agent: 5 mass % of
(Tris(glycidoxypropyldimethylsiloxy)phenylsilane (SIT8715.6,
manufactured by Gelest Inc.)
[0225] (c) second cross-linking agent: 1 mass % of bisphenol A
epoxy monomer (RE-310s, manufactured by Nippon Kayaku Co.,
Ltd.)
[0226] (d) photocationic polymerization initiator: 0.5 mass % of
(thiophenoxyphenyl)diphenylsulfonium
hexafluorophosphate-bis(diphenylsulfonium)diphenylthioether
hexafluorophosphate blend, 50% in propylene carbonate (OMPH076,
manufactured by Gelest Inc.)
[0227] (e) solvent: 89.5 mass % of cyclohexanone
[0228] (Raw Material Solution 2)
[0229] Raw material solution 2 was prepared in the same manner as
raw material solution 1, except that
PSS-Octa[(3-glycidyloxypropyl)dimethylsiloxy]substituted (593869,
manufactured by Sigma-Aldrich Corporation) was used as the first
cross-linking agent (b).
[0230] (Raw Material Solution 3) Raw material solution 3 was
prepared in the same manner as raw material solution 1, except that
tetraphenylol ethane glycidyl ether (412961, manufactured by
Sigma-Aldrich Corporation) represented by Formula (100) below was
used as the first cross-linking agent (b).
##STR00005##
[0231] (Raw Material Solution 4)
[0232] Raw material solution 4 was prepared in the same manner as
raw material solution 1, except that poly(2-hydroxyethyl
methacrylate) (529265, manufactured by Sigma-Aldrich Corporation)
was used as the organic compound (a) having a hydroxy group.
[0233] The raw material solution was applied on a PET substrate
(Model number: A-4100 (no coat), manufactured by Toyobo Co., Ltd.)
by spin coating (1500 rpm.times.30 seconds). Then, the substrate
was heated at 105.degree. C. for 5 minutes to volatilize
cyclohexanone as a solvent to form a coating film of a curable
composition on the PET substrate.
[0234] Next, the coating film was irradiated with i-line ray (365
nm) at an irradiation intensity of 500 mJ/cm.sup.2 through a
photomask having a pattern of L/S=30 .mu.m/30 .mu.m and was further
heated (post-baked) at 105.degree. C. for 10 minutes. Then, the
substrate was immersed into 2.38 mass % of an aqueous TMAH solution
for 1 minute to be developed.
[0235] FIG. 7 shows optical microscope images of insulator layers
after the development. FIG. 7(a) shows a result when raw material
solution 1 was used. FIG. 7(b) shows a result when raw material
solution 2 was used. FIG. 7(c) shows a result when raw material
solution 3 was used. FIG. 7(d) shows a result when raw material
solution 4 was used.
[0236] As shown in FIG. 7, in a case where raw material solution 1
was used, in a case where raw material solution 2 was used, and in
a case where raw material solution 4 was used, it was possible to
obtain a good pattern having a width of 30 .mu.m for all cases. On
the other hand, in a case where raw material solution 3 using
tetraphenylol ethane glycidyl ether as the first cross-linking
agent, it was impossible to perform the development by the aqueous
TMAH solution at all, and it was impossible to obtain a
pattern.
Example 2
[0237] FIGS. 8A to 8C are views showing a process of manufacturing
the sandwich cell evaluated in Example 2.
[0238] First, an insulator layer and a base film were laminated
(refer to FIG. 8B) on a silicon substrate (n-type abrasive product,
.ltoreq.0.003.OMEGA. cm, manufactured by Nakayama Semiconductor
Co., Ltd.) (refer to FIG. 8A) by the following method.
[0239] Specifically, raw material solution 2 of Example 1 described
above was applied onto the silicon substrate by spin coating (1000
rpm.times.30 seconds). Then, the substrate was heated at
105.degree. C. for 5 minutes to volatilize cyclohexanone (solvent),
and a coating film of a curable composition was formed on the
silicon substrate.
[0240] Next, the coating film was irradiated with i-line ray (365
nm) at an irradiation intensity of 700 mJ/cm.sup.2 through a
photomask, was further heated (post-baked) at 120.degree. C. for 10
minutes, and then immersed in 2.38 mass % of an aqueous TMAH
solution for 1 minute to be developed, so as to form an insulator
layer.
[0241] The surface of the formed insulator layer was cleaned with
atmospheric-pressure oxygen plasma, and then a silane coupling
agent, which is a formation material of a base film for electroless
plating, was formed into a film. In the present Example, as the
silane coupling agent, 3-aminopropyltriethoxysilane having a
primary amino group (KBE-903, manufactured by Shin-Etsu Silicone
Co., Ltd.) was used. The silane coupling agent was dissolved in
methyl isobutyl ketone to have a content of 0.2 mass % to obtain a
liquid product, and then the liquid product was applied onto the
substrate by spin coating (4000 rpm.times.30 seconds). Thereafter,
the substrate coated with the liquid product was heated at
120.degree. C. for 5 minutes to volatilize methyl isobutyl ketone
(solvent), so as to form a base film.
[0242] Then, hexamethyldisiloxane (hereinafter, sometimes referred
to as "HMDS") was applied onto the surface of the base film by spin
coating (2000 rpm.times.30 seconds) and was heated at 120.degree.
C. for 5 minutes.
[0243] Next, as shown in FIG. 8C, an upper electrode was formed on
the base film, and a sandwich cell was fabricated.
[0244] Specifically, a photoresist (SUMIRESIST PFI-34A,
manufactured by Sumitomo Chemical Co., Ltd.) was applied to the
surface of the base film coated with HMDS by spin coating (1000
rpm.times.30 seconds), and heated at 90.degree. C. for 5 minutes,
so as to form a resist layer.
[0245] Next, the resist layer was irradiated with light emitted
from a low-pressure mercury lamp through a quartz photomask for 5
minutes, heated (post-baked) at 110.degree. C. for 5 minutes, and
then immersed into 2.38 mass % of an aqueous TMAH solution for 90
seconds to thereby develop the resist layer, so as to form an
opening in the resist layer.
[0246] Next, the substrate provided with the resist layer having
the opening was washed with water at room temperature for 30
seconds, and then immersed into a catalyst colloid solution for
electroless plating (Melplate activator 7331, manufactured by
Meltex Corporation) at room temperature for 60 seconds, so as to
adhere a catalyst to the base film exposed through the opening of
the resist layer.
[0247] Next, the surface of the base film was washed with water,
and then immersed into an electroless plating solution (Melplate
NI-867, manufactured by Meltex Corporation) at 70.degree. C. for
180 seconds to deposit nickel phosphorus on the catalyst adhered to
the opening of the resist layer, so as to perform nickel-phosphorus
plating.
[0248] Next, the surface of the nickel-phosphorus plated portion
(NiP electrode) was washed with water, and then immersed into a
gold plating bath for substitution for 1 minute and further
immersed into a plating bath for reduction for 3 minutes to thereby
perform electroless gold plating on the upper surface of the NiP
electrode and coat the upper surface of the NiP electrode with
gold, so as to fabricate an upper electrode.
[0249] Next, the surface of the upper electrode was water-washed
and then dried. Then, the entire surface including the remaining
resist layer was irradiated with i-line ray at an irradiation
intensity of 300 mJ/cm.sup.2, and then immersed into 2.38 mass % of
an aqueous TMAH solution to remove the resist layer. The resulting
product was water-washed and dried to thereby fabricate a sandwich
cell.
[0250] The dielectric constant and insulation characteristics of
the insulator layer were measured using the fabricated sandwich
cell by the following method.
[0251] (Dielectric Constant)
[0252] The measurement of capacitance of the fabricated insulator
layer was performed in a frequency range of 100 Hz to 1 MHz using
an LCR meter (4284A, manufactured by Agilent Technologies).
[0253] FIG. 9 is a graph showing the frequency dependency of
dielectric constant calculated from capacitance of the insulator
layer of the fabricated sandwich cell. In the graph of FIG. 9, the
horizontal axis indicates the measurement frequency (unit: Hz), and
the vertical axis indicates the measured dielectric constant.
[0254] It was found that the insulator layer fabricated in Example
2 had a high dielectric constant greater than .di-elect cons.=3.9,
which is a dielectric constant of a SiO.sub.2 thermal oxide film
(generally known inorganic insulator), with respect to any
measurement frequency.
[0255] (Insulating Characteristics)
[0256] In the evaluation of insulating characteristics of the
fabricated insulator layer, current density was measured using the
Semiconductor Characterization System (4200-SCS, manufactured by
KEITHLEY Co., Ltd.) when a voltage of 0 MV/cm to 2 MV/cm was
applied.
[0257] FIG. 10 is a graph showing the evaluation result of
insulating characteristics of the insulator layer of the fabricated
sandwich cell. In the graph of FIG. 10, the horizontal axis
indicates the measurement voltage (unit: MV/cm), and the vertical
axis indicates the measured current density (A/cm.sup.2).
[0258] Most of general resin-based insulators have a current
density on the order of 1.times.10.sup.-7 A/cm.sup.2. On the other
hand, it was found that the current density of the insulator layer
fabricated in Example 2 was a value on the order of
1.times.10.sup.-8 A/cm.sup.2 with respect to any measurement
voltage and the insulator layer had improved insulation
properties.
Example 3
Fabrication of Gate Electrode
[0259] In Example 3, 3-aminopropyltriethoxysilane (KBE903,
manufactured by Shin-Etsu Silicone Co., Ltd.), which is an
amine-based silane coupling agent, was dissolved in methyl isobutyl
ketone (hereinafter, sometimes referred to as MIBK) to have 0.2
mass % to prepare a liquid product, and this liquid product was
used in forming a base film.
[0260] The surface of a PET substrate (Model number: A-4100 (no
coat), manufactured by Toyobo Co., Ltd.) was cleaned with
atmospheric-pressure oxygen plasma, and then the above liquid
product was applied onto the PET substrate by spin coating (4000
rpm.times.30 seconds). Thereafter, the PET substrate coated with
the liquid product was heated at 120.degree. C. for 10 minutes, so
as to form a base film.
[0261] Next, a resist material (SUMIRESIST PFI-34A6, manufactured
by Sumitomo Chemical Co., Ltd.) was applied to the surface of the
substrate provided with the base film by spin coating, and then
heated (prebaked) at 90.degree. C. for 5 minutes, so as to form a
resist layer. The spin coating was performed under a condition of
1000 rpm and 30 seconds, and a resist layer having a thickness of
about 1 .mu.m was formed.
[0262] Next, the resist layer was exposed with ultraviolet having
an intensity of 25 mW/cm.sup.2 through a photomask for 5 seconds,
heated (post-baked) at 110.degree. C. for 5 minutes, and then
immersed into 2.38 mass % of an aqueous TMAH solution for 2 minutes
to thereby develop a mask pattern on the resist layer, so as to
form an opening.
[0263] Next, the substrate provided with the resist layer having
the opening was ultrasonically water-washed at room temperature for
30 seconds, and then immersed into a catalyst colloid solution for
electroless plating (Melplate activator 7331, manufactured by
Meltex Corporation) at room temperature for 60 seconds, so as to
adhere a catalyst (Pd metal) to the base film exposed through the
opening of the resist layer.
[0264] Next, the surface of the base film was washed with water,
and then immersed into an electroless plating solution (Melplate
NI-867, manufactured by Meltex Corporation) at 73.degree. C. for 60
seconds to deposit nickel phosphorus on the catalyst adhered to the
opening of the resist layer, so as to perform nickel-phosphorus
plating.
[0265] Next, the surface of the resulting product was water-washed
and then dried. Then, the entire surface including the remaining
resist layer was exposed to ultraviolet having an intensity of 25
mW/cm.sup.2 for 1 minute, and then immersed into ethanol for 1
minute to thereby remove the resist layer, so as to fabricate a
gate electrode.
[0266] FIG. 11 shows photographs of the gate electrode. FIG. 11 (a)
is an overall photograph of the substrate provided with the gate
electrode. FIG. 11 (b) is an enlarged photograph of the gate
electrode using an optical microscope. From FIG. 11, it is found
that a slightly uneven flat gate electrode is formed.
[0267] (Fabrication of Insulator Layer)
[0268] In order to improve the adhesiveness between the gate
electrode and the insulator layer to be formed, the substrate
provided with the gate electrode was immersed into an aqueous NaOH
solution of 50 g/L, and a degreasing process of the surface was
performed.
[0269] Next, an aqueous solution of a silane coupling agent
(3-glycidoxypropyl triethoxysilane, KBM-403, manufactured by
Shin-Etsu Silicone Co., Ltd.) was applied to the whole surface, on
which the gate electrode was formed, of the PET substrate by spin
coating, and the substrate was heated at 120.degree. C. for 10
minutes. Thereafter, the raw material solution 2 of Example 1 was
applied onto the surface by spin coating (1000 rpm.times.30
seconds). Then, the resulting product was heated at 105.degree. C.
for 5 minutes to volatilize cyclohexanone (solvent), so as to form
a coating film of a curable composition.
[0270] Next, the coating film was irradiated with ultraviolet for
25 seconds through a mask having an opening in the portion forming
an insulator layer. In order to accelerate curing, the
ultraviolet-irradiated coating film was heated at 120.degree. C.
for 10 minutes, and then immersed into 2.38 mass % of an aqueous
TMAH solution for 1 minute to form a patterned film. Then, the
patterned film was heat-treated at 120.degree. C. for 30 minutes to
form an insulator layer.
[0271] FIG. 12 is a photograph of the insulator layer. FIG. 12 (a)
is an overall photograph of the substrate provided with the
insulator layer. FIG. 12 (b) is an enlarged photograph of the
insulator layer of the region surrounded by the dash line of FIG.
12 (a). As a result of the observation, it was confirmed that the
insulator layer was formed without unevenness and a slightly uneven
flat insulator layer was formed by development with an alkaline
solution.
[0272] (Fabrication of Source and Drain Electrodes)
[0273] Next, the fabrication and electroless plating of the base
film and the resist layer were performed on the entire surface of
the side where the insulator layer was formed on the PET substrate
in the same manner as the above-mentioned process (fabrication of
the gate electrode), so as to form a patterned NiP electrode on the
insulator layer. The NiP electrode corresponds to the first
electrode and the third electrode described in the embodiment.
[0274] In addition, after stripping the resist, the NiP electrode
was immersed into a gold plating bath for substitution for 1 minute
and further immersed into a plating bath for reduction for 3
minutes to thereby perform electroless gold plating to coat the
surface of the NiP electrode with gold, so as to fabricate a source
electrode and a drain electrode. The gold film coating the surface
of the NiP electrode corresponds to the second electrode and the
fourth electrode described in the embodiment.
[0275] FIG. 13 shows the photographs of the source electrode and
the drain electrode.
[0276] FIG. 13 (a) is an overall photograph of the substrate
provided with the source electrode and the drain electrode. FIG. 13
(b) is an enlarged photograph of the source electrode and the drain
electrode. As a result of the observation, in the surface of the
insulator layer of the present invention, it was confirmed that a
good source electrode and a good drain electrode were formed.
Further, damage to the insulator layer in the electroless plating
process was not confirmed.
[0277] (Fabrication of Organic Semiconductor Layer)
[0278] A toluene solution of
6,13-bis(triisopropylsilylethynyl)pentacene (TIPS pentacene)
(716006, manufactured by Sigma-Aldrich, Inc.) was dropped between
the source electrode and the drain electrode under a nitrogen
atmosphere, and naturally dried to thereby form a semiconductor
layer, so as to fabricate a transistor. Here, the adjustment of the
TIPS pentacene/toluene solution used was also performed under a
nitrogen atmosphere.
[0279] FIG. 14 shows an enlarged photograph of the source electrode
and the drain electrode having the surface provided with the
organic semiconductor layer. It was observed that crystals of TIPS
pentacene were formed between the source electrode and the drain
electrode.
[0280] (Evaluation of Transistor)
[0281] The transistor characteristics of the fabricated transistor
were evaluated using the Semiconductor Characterization System
(4200-SCS, manufactured by KEITHLEY Co., Ltd.).
[0282] FIG. 15 shows a graph showing the transistor characteristics
of the transistor fabricated by a wet process using the
above-mentioned method. In the graph of FIG. 15, the horizontal
axis indicates a voltage applied between the source electrode and
the drain electrode, and the vertical axis indicates a current
value detected by the drain electrode. One of the plurality of
results shown in FIG. 15 corresponds to each of the gate voltages
applied to a gate electrode.
[0283] A gate voltage of 0 V to -40 V was applied to the gate
electrode of the obtained organic thin film transistor, and a
voltage of 0 V to -50 V was applied between source and drain to
flow electric current. As a result, as shown in FIG. 15, holes are
induced in the channel region (between source and drain) of a
semiconductor layer, and the fabricated transistor was operated as
a p-type transistor.
[0284] From the above results, it was found that, when a
composition according to the aspect of the present invention was
used to form an insulator layer by development with an alkaline
solution, it was possible to fabricate a transistor (organic thin
film transistor) in an all wet process. Further, it was found that,
when the base film was formed using a silane coupling agent
(primary amine), the treatment using an accelerator was not
required, and the operation of electroless plating was simplified.
Further, it was found that, since the base film formed using a
silane coupling agent was a flat film having very small unevenness,
at the time of forming a laminated structure, uneven shape was not
imparted to the configuration of the upper layer of the base film,
and it was possible to fabricate a high-performance transistor.
Moreover, it was found that, since it was possible to coat the
entire surface of source and drain electrodes with a metal material
having a work function that provides a small energy gap with HOMO
of the formation material of the organic semiconductor layer by
using an electroless plating method, it was possible to provide a
transistor having small electrical contact resistance between the
organic semiconductor layer and the source and drain
electrodes.
[0285] From the above results, the usefulness of the present
invention has been confirmed.
* * * * *