U.S. patent application number 13/795131 was filed with the patent office on 2014-01-23 for etching paste, method of preparing the same, and method of forming pattern using the same.
The applicant listed for this patent is Jae Joon SHIM. Invention is credited to Jae Joon SHIM.
Application Number | 20140023827 13/795131 |
Document ID | / |
Family ID | 49946768 |
Filed Date | 2014-01-23 |
United States Patent
Application |
20140023827 |
Kind Code |
A1 |
SHIM; Jae Joon |
January 23, 2014 |
ETCHING PASTE, METHOD OF PREPARING THE SAME, AND METHOD OF FORMING
PATTERN USING THE SAME
Abstract
An etching paste includes an acid compound, an organic binder, a
nitrogen-containing component, the nitrogen-containing component
including one or more of an amine compound or an ammonium compound,
a cobalt aluminum oxide, and a solvent.
Inventors: |
SHIM; Jae Joon; (Uiwang-si,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHIM; Jae Joon |
Uiwang-si |
|
KR |
|
|
Family ID: |
49946768 |
Appl. No.: |
13/795131 |
Filed: |
March 12, 2013 |
Current U.S.
Class: |
428/156 ;
216/101; 216/103; 216/83; 252/79.1; 252/79.4 |
Current CPC
Class: |
C23F 1/20 20130101; C09K
13/08 20130101; Y10T 428/24479 20150115; C23F 1/10 20130101; H01L
31/02363 20130101; Y02E 10/50 20130101 |
Class at
Publication: |
428/156 ;
252/79.1; 252/79.4; 216/83; 216/103; 216/101 |
International
Class: |
C23F 1/10 20060101
C23F001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 17, 2012 |
KR |
10-2012-0077882 |
Claims
1. An etching paste, comprising: an acid compound; an organic
binder; a nitrogen-containing component, the nitrogen-containing
component including one or more of an amine compound or an ammonium
compound; a cobalt aluminum oxide; and a solvent.
2. The etching paste as claimed in claim 1, wherein the cobalt
aluminum oxide is present in an amount of about 1 wt % to about 20
wt % in the etching paste.
3. The etching paste as claimed in claim 1, wherein the cobalt
aluminum oxide has an average particle diameter (D50) of about
0.001 .mu.m to about 5 .mu.m
4. The etching paste as claimed in claim 1, wherein a mole ratio of
the nitrogen-containing component to the acid compound is about 1
to about 1.5.
5. The etching paste as claimed in claim 1, wherein the
nitrogen-containing component includes the amine compound, and the
amine compound is represented by Formula 1: (R).sub.n--N--H.sub.m
[Formula 1] wherein, in Formula 1, R is a substituted or
unsubstituted C1 to C12 alkyl group, a substituted or unsubstituted
C6 to C12 aryl group, or a substituted or unsubstituted C7 to C15
arylalkyl group, n is an integer from 1 to 3, m is an integer from
0 to 2, and n+m is 3.
6. The etching paste as claimed in claim 1, wherein the
nitrogen-containing component includes the ammonium compound, and
the ammonium compound is represented by Formula 2:
(NH.sub.4).sub.kX [Formula 2] wherein, in Formula 2, X is CO.sub.3,
OH, or CO.sub.2NH.sub.2, and k is 1 or 2.
7. The etching paste as claimed in claim 1, wherein the acid
compound includes one or more of phosphoric acid, hydrogen
fluoride, ammonium fluoride, or ammonium hydrogen fluoride.
8. The etching paste as claimed in claim 1, wherein the organic
binder includes one or more of methyl cellulose, ethyl cellulose,
hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl
cellulose, sodium carboxymethyl cellulose, sodium carboxymethyl
hydroxyethyl cellulose, nitrocellulose, xanthan gum, starch,
gelatin, polyvinyl butyral, a polyamide resin, thixotron,
polyvinylpyrrolidone, polyvinyl alcohol, an acrylic polymer
obtained by copolymerization of acrylic monomers having a hydroxyl
group or a carboxylic acid group, a water-soluble (meth)acrylic
resin, a polyether-polyol, or a poly(ether urea)-polyurethane.
9. The etching paste according to claim 1, wherein the etching
paste comprises: about 15 wt % to about 50 wt % of the acid
compound, about 3 wt % to about 20 wt % of the organic binder,
about 0.1 wt % to about 10 wt % of the nitrogen-containing
component, about 1 wt % to about 20 wt % of the cobalt aluminum
oxide, and a balance of the solvent.
10. The etching paste as claimed in claim 1, further comprising one
or more of an organic acid, inorganic particles, a foaming agent, a
leveling agent, an antifoaming agent, a thickener, a thixotropic
agent, a plasticizer, a dispersant, a viscosity stabilizer, a UV
stabilizer, an antioxidant, or a coupling agent.
11. The etching paste as claimed in claim 1, further comprising
inorganic particles, wherein a weight ratio of the cobalt aluminum
oxide to the inorganic particles is about 0.1 to about 7.
12. The etching paste as claimed in claim 1, wherein the acid
compound includes phosphoric acid, the organic binder includes
hydroxypropyl cellulose, the nitrogen-containing component includes
one or more of ammonium hydroxide 35% or methylamine, the cobalt
aluminum oxide includes CoAl.sub.2O.sub.4, and the solvent includes
water and n-methylpyrrolidone, the etching paste further comprises
acetic acid and silica particles, a weight ratio of the
CoAl.sub.2O.sub.4 to the silica particles is about 0.4 to about
6.5, a mole ratio of the phosphoric acid to the nitrogen-containing
component is about 1:1.1 to about 1:1.3, and the etching paste
comprises: about 25 wt % to about 30 wt % of the phosphoric acid,
about 5 wt % to about 10 wt % of the hydroxypropyl cellulose, about
0.1 wt % to about 0.5 wt % of the nitrogen-containing component,
about 1 wt % to about 15 wt % of the CoAl.sub.2O.sub.4, about 1 wt
% to about 5 wt % of the acetic acid, about 1 wt % to about 5 wt %
of the silica particles, and a balance of the solvent.
13. A method of forming a pattern, the method comprising: printing
the etching paste as claimed in claim 1 on a substrate on which an
etching target is deposited; drying the etching paste; and washing
the etching paste to form a pattern in the etching target.
14. The method as claimed in claim 13, wherein the etching target
is aluminum or indium tin oxide.
15. A device comprising a pattern formed by the method as claimed
in claim 13.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The application claims the benefit of and priority to Korean
Patent Application No. 10-2012-0077882, filed on Jul. 17, 2012, in
the Korean Intellectual Property Office, and entitled: "ETCHING
PASTE, METHOD OF PREPARING THE SAME, AND METHOD OF FORMING PATTERN
USING THE SAME," which is incorporated by reference herein in its
entirety.
BACKGROUND
[0002] 1. Field
[0003] Embodiments relate to an etching paste, a method of
preparing the same, and a method of forming a pattern using the
same.
[0004] 2. Description of the Related Art
[0005] A pattern forming process may be used for semiconductor
devices and flat panel displays such as LCDs, OLEDs, and PDPs. A
typical pattern forming process is performed using a photosensitive
material such as photoresist, in which a photoresist layer is
formed by depositing the photoresist on a metal layer formed on a
substrate of an insulating material, such as glass, or a
semiconductor material, followed by exposure and development
through a photo mask. Then, the metal layer it etched using an
etching solution and the photoresist pattern is removed using a
stripper, leaving a metal pattern on the substrate.
[0006] Such a metal pattern formation process using photoresist may
involve a complicated manufacturing process since a pattern is
formed via photoresist application, baking, exposure, and
development. Particularly, a soft baking process at a particular
temperature and a hard baking process at a higher temperature than
the soft baking temperature may be needed to bake the photoresist,
thereby making the process complicated. As a result, the typical
pattern forming process may have undesirable characteristics such
as increase in manufacturing costs, environmental contamination due
to waste photoresist contaminates, and device defects caused by
remaining photoresist.
SUMMARY
[0007] Embodiments are directed to an etching paste, including an
acid compound, an organic binder, a nitrogen-containing component,
the nitrogen-containing component including one or more of an amine
compound or an ammonium compound, a cobalt aluminum oxide, and a
solvent.
[0008] The cobalt aluminum oxide may be present in an amount of
about 1 wt % to about 20 wt % in the etching paste.
[0009] The cobalt aluminum oxide may have an average particle
diameter (D50) of about 0.001 .mu.m to about 5 .mu.m
[0010] A mole ratio of the nitrogen-containing component to the
acid compound may be about 1 to about 1.5.
[0011] The nitrogen-containing component may include the amine
compound, and the amine compound may be represented by Formula
1:
(R).sub.n--N--H.sub.m [Formula 1]
[0012] wherein, in Formula 1, R may be a substituted or
unsubstituted C1 to C12 alkyl group, a substituted or unsubstituted
C6 to C 12 aryl group, or a substituted or unsubstituted C7 to C15
arylalkyl group, n may be an integer from 1 to 3, m may be an
integer from 0 to 2, and n+m may be 3.
[0013] The nitrogen-containing component may include the ammonium
compound, and the ammonium compound may be represented by Formula
2:
(NH.sub.4).sub.kX [Formula 2]
[0014] wherein, in Formula 2, X may be CO.sub.3, OH, or
CO.sub.2NH.sub.2, and k may be 1 or 2.
[0015] The acid compound may include one or more of phosphoric
acid, hydrogen fluoride, ammonium fluoride, or ammonium hydrogen
fluoride.
[0016] The organic binder may include one or more of methyl
cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl
cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose,
sodium carboxymethyl hydroxyethyl cellulose, nitrocellulose,
xanthan gum, starch, gelatin, polyvinyl butyral, a polyamide resin,
thixoton, polyvinylpyrrolidone, polyvinyl alcohol, an acrylic
polymer obtained by copolymerization of acrylic monomers having a
hydroxyl group or a carboxylic acid group, a water-soluble
(meth)acrylic resin, a polyether-polyol, or a poly(ether
urea)-polyurethane.
[0017] The etching paste may include about 15 wt % to about 50 wt %
of the acid compound, about 3 wt % to about 20 wt % of the organic
binder, about 0.1 wt % to about 10 wt % of the nitrogen-containing
component, about 1 wt % to about 20 wt % of the cobalt aluminum
oxide, and a balance of the solvent.
[0018] The etching paste may further include one or more of an
organic acid, inorganic particles, a foaming agent, a leveling
agent, an antifoaming agent, a thickener, a thixotropic agent, a
plasticizer, a dispersant, a viscosity stabilizer, a UV stabilizer,
an antioxidant, or a coupling agent.
[0019] The etching paste may further include inorganic particles. A
weight ratio of the cobalt aluminum oxide to the inorganic
particles may be about 0.1 to about 7.
[0020] The acid compound may include phosphoric acid, the organic
binder may include hydroxypropyl cellulose, the nitrogen-containing
component may include one or more of ammonium hydroxide 35% or
methylamine, the cobalt aluminum oxide may include
CoAl.sub.2O.sub.4, and the solvent may include water and
n-methylpyrrolidone, the etching paste may further include acetic
acid and silica particles, a weight ratio of the CoAl.sub.2O.sub.4
to the silica particles may be about 0.4 to about 6.5, a mole ratio
of the phosphoric acid to the nitrogen-containing component may be
about 1:1.1 to about 1:1.3, and the etching paste may include:
about 25 wt % to about 30 wt % of the phosphoric acid, about 5 wt %
to about 10 wt % of the hydroxypropyl cellulose, about 0.1 wt % to
about 0.5 wt % of the nitrogen-containing component, about 1 wt %
to about 15 wt % of the CoAl.sub.2O.sub.4, about 1 wt % to about 5
wt % of the acetic acid, about 1 wt % to about 5 wt % of the silica
particles, and a balance of the solvent.
[0021] Embodiments are also directed to a method of forming a
pattern, the method including printing the etching paste according
to an embodiment on a substrate on which an etching target is
deposited, drying the etching paste, and washing the etching paste
to form a pattern in the etching target.
[0022] The etching target may be aluminum or indium tin oxide.
[0023] Embodiments are also directed to a device including a
pattern formed by the method according to an embodiment.
BRIEF DESCRIPTION OF DRAWINGS
[0024] Features will become apparent to those of skill in the art
by describing in detail example embodiments with reference to the
attached drawings in which:
[0025] FIG. 1 illustrates stages in a method of forming a pattern
according to an embodiment.
[0026] FIG. 2 illustrates a flowchart of the method of forming a
pattern according to an embodiment.
[0027] FIG. 3 illustrates a distal end of a pattern after etching
in Example 1.
[0028] FIG. 4 illustrates a distal end of a pattern after etching
in Comparative Example 1.
DETAILED DESCRIPTION
[0029] Example embodiments will now be described more fully
hereinafter with reference to the accompanying drawings; however,
they may be embodied in different forms and should not be construed
as limited to the embodiments set forth herein. Rather, these
embodiments are provided so that this disclosure will be thorough
and complete, and will fully convey example implementations to
those skilled in the art.
[0030] In the drawing figures, the dimensions of layers and regions
may be exaggerated for clarity of illustration. It will also be
understood that when a layer or element is referred to as being
"on" another layer or substrate, it can be directly on the other
layer or substrate, or intervening layers may also be present.
Further, it will be understood that when a layer is referred to as
being "under" another layer, it can be directly under, and one or
more intervening layers may also be present. In addition, it will
also be understood that when a layer is referred to as being
"between" two layers, it can be the only layer between the two
layers, or one or more intervening layers may also be present. Like
reference numerals refer to like elements throughout.
[0031] An embodiment provides an etching paste including: an acid
compound; an organic binder; nitrogen-containing component
including one or more of an amine compound or an ammonium compound;
a cobalt aluminum oxide; and a solvent.
[0032] Acid Compound
[0033] The acid compound may include a suitable compound capable of
etching an etching target (for example, metal, or indium tin oxide
(ITO)) on which the etching paste acts. For example, the acid
compound may include inorganic acid, for example one or more of
phosphoric acid, hydrogen fluoride, ammonium fluoride, or ammonium
hydrogen fluoride. In an implementation, phosphoric acid may be
used.
[0034] The acid compound may be used as an acid solution having a
concentration of about 80% or higher, e.g., about 85% to 90% (based
on weight). In an implementation, a phosphoric acid aqueous
solution may be used.
[0035] The acid compound or a solution containing the acid compound
may be present in an amount of about 15 wt % to about 50 wt % in
the etching paste. Within this range, the etching paste may exhibit
excellent etching performance while reducing effects on equipment.
The acid compound or the solution containing the acid compound may
be present in an amount of, e.g., about 20 wt % to about 35 wt %,
or about 25 wt % to about 30 wt %, in the etching paste.
[0036] Organic Binder
[0037] The organic binder may enhance viscosity and printability of
the etching paste, so as to enable printing of the etching
paste.
[0038] The organic binder may include, e.g., cellulose derivatives
including methyl cellulose, ethyl cellulose, hydroxyethyl
cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, sodium
carboxymethyl cellulose, sodium carboxymethyl hydroxyethyl
cellulose and nitrocellulose, xanthan gum, starch, gelatin,
polyvinyl butyral, a polyamide resin, thixotron,
polyvinylpyrrolidone, polyvinyl alcohol, water-soluble
(meth)acrylic resins including acrylic polymers obtained by
copolymerization of acrylic monomers having a hydrophilic group,
such as a hydroxyl group and a carboxylic acid group,
polyether-polyol, and poly(ether urea)-polyurethane, etc. The
organic binder may be used alone or in combination of two or more
thereof.
[0039] The organic binder may be present in an amount of about 3 wt
% to about 20 wt % in the etching paste. Within this range, the
etching paste may have a suitable viscosity and printability may be
enhanced. The organic binder may be present in an amount of about 5
wt % to about 15 wt %, or about 5 wt % to about 10 wt %.
[0040] Nitrogen-containing component including one or more of an
amine compound or an ammonium compound
[0041] The amine compound and/or the ammonium compound may react
with the acid compound to form a complex, which is separated at
about 100 to 250.degree. C. to have an etching function.
[0042] The amine compound may be represented by Formula 1:
(R).sub.n--N--H.sub.m, [Formula 1]
[0043] where, in Formula 1, R may be a substituted or unsubstituted
C1 to C12 alkyl group, a substituted or unsubstituted C6 to C12
aryl group, or a substituted or unsubstituted C7 to C 15 arylalkyl
group, n may be an integer from 1 to 3, m may be an integer from 0
to 2, and n+m may equal 3. When R is substituted, a substituent may
be, e.g., a C1 to C5 alkyl group or a C6 to 10 aryl group.
[0044] In an implementation, R may be a C1 to C10 alkyl group or a
C7 to C10 arylalkyl group.
[0045] In an implementation, n may be 1 or 2, and m may be 1 or
2.
[0046] Examples of the amine compound may include methyl amine,
ethyl amine, propyl amine, butyl amine, dodecyl amine, benzyl
amine, etc. The amine compound may be used alone or in combination
of two or more thereof.
[0047] The ammonium compound may be represented by Formula 2:
(NH.sub.4).sub.kX, [Formula 2]
[0048] where, in Formula 2, X may be OH, CO.sub.3, or
CO.sub.2NH.sub.2, and k may be 1 or 2.
[0049] Examples of the ammonium compound may include an ammonia
solution (ammonia water), ammonium carbonate, ammonium carbamate,
etc. The ammonium compound may be used alone or in combination of
two or more thereof.
[0050] In an implementation, the ammonium compound may be an
ammonia solution (ammonia water).
[0051] The amine compound and the ammonium compound may be used as
a combination thereof.
[0052] A mole ratio of the amine compound and/or the ammonium
compound to the acid compound may range from about 1 to about 1.5.
Within this range, the etching paste may be neutralized while
reducing or avoiding decreases in printability. In an
implementation, a mole ratio between the acid compound and the
amine compound, the ammonium compound, or a mixture thereof may be
about 1:1.1 to about 1:1.3.
[0053] The nitrogen-containing component may be present in an
amount of about 0.1 wt % to about 10 wt % in the etching paste.
Within this range, the etching paste may exhibit excellent etching
performance while reducing effects on equipment. In an
implementation, the amount may be about 0.1 wt % to about 1 wt %,
or about 0.1 wt % to about 0.5 wt %, in the etching paste.
[0054] Cobalt Aluminum Oxide
[0055] The etching paste may form a metal pattern through screen
printing. The etching paste may be printed on an etching target,
dried through heat treatment or the like, and washed, thereby
forming the metal pattern.
[0056] In forming the metal pattern, etching proceeds faster as
heat treatment temperature rises. The color of the cobalt aluminum
oxide changes from blue into black depending on the extent of
etching. This color change may help make it possible to identify
the extent of etching, an etched position on a substrate, and/or a
substrate state before and after heat treatment with the naked
eye.
[0057] Further, the cobalt aluminum oxide may allows etching at low
temperature, for example, at a heat treatment temperature of about
100.degree. C. to about 150.degree. C., thereby securing a pattern
in a predetermined range of line width, for example, a fine line
width of about 50 .mu.m to about 200 .mu.m. The pattern may become
finer with increasing heat treatment temperature.
[0058] In addition, the cobalt aluminum oxide may itself be etched
to prevent expansion of etching at the distal end of the etched
metal, thereby reducing or preventing resistance increase due to
expansion of etching, which may otherwise occur.
[0059] In some embodiments, the cobalt aluminum oxide may include
CoAl.sub.2O.sub.4.
[0060] The cobalt aluminum oxide may be a nano-scaling powder. The
powder may have an average particle diameter (D50) of, e.g., about
0.001 .mu.m to about 5 .mu.m, or about 0.1 .mu.m to about 2 .mu.m,
or about 0.1 .mu.m to about 1.0 .mu.m.
[0061] The cobalt aluminum oxide may be present in an amount of
about 1 wt % to about 20 wt % in the etching paste. Within this
range, the etching paste may have excellent printability, superior
resolution after printing, and excellent visibility. The cobalt
aluminum oxide may be present in an amount of about 1 wt % to about
15 wt %.
[0062] Solvent
[0063] As the solvent, a suitable solvent that does not
significantly reduce water-solubility of the etching paste may be
used. Examples of the solvent may include water (including
distilled water), n-methylpyrrolidone (NMP), ethylene glycol butyl
ether, propylene carbonate, ethylene glycol, N-methyl-2-pyridone,
ethylene glycol monoacetate, diethylene glycol, diethylene glycol
acetate, tetraethylene glycol, propylene glycol, propylene glycol
monomethyl ether, trimethylene glycol, glyceryl diacetate, hexylene
glycol, dipropyl glycol, oxylene glycol, 1,2,6-hexanetriol,
glycerin, etc. These solvents may be used alone or in combination
of two or more thereof.
[0064] The solvent may be added to the etching paste as a remaining
amount (i.e., a balance)--excluding the acid compound, the organic
binder, the nitrogen-containing component including one or more of
the amine compound or the ammonium compound, the cobalt aluminum
oxide, and additive(s) (if included). In an embodiment, the solvent
may be present in an amount of about 25 wt % to about 60 wt %, or
about 35 wt % to about 55 wt %, in the etching paste.
[0065] The etching paste may include one or more additives, e.g.,
to improve fluidity, processibility, stability, etc. The
additive(s) may include, e.g., an organic acid, inorganic
particles, a foaming agent, a leveling agent, an antifoaming agent,
a thickener, a thixotropic agent, a plasticizer, a dispersant, a
viscosity stabilizer, a UV stabilizer, an antioxidant, a coupling
agent, etc. The additive may be used alone or in combination of two
or more thereof.
[0066] The organic acid may include, e.g., acetic acid, lactic
acid, malonic acid, citric acid, etc. The organic acid may be
present in an amount of about 0.1 wt % to about 10 wt %, e.g.,
about 1 wt % to about 5 wt %, in the etching paste.
[0067] The inorganic particles may include silica, carbon black,
iron pigments, titanium dioxide, etc. A weight ratio of the cobalt
aluminum oxide to the inorganic particles may be about 0.1 to 7,
e.g., about 0.4 to about 6.5. The inorganic particles may be
present in an amount of about 1 wt % to about 15 wt %, e.g., about
1 wt % to about 5 wt %, in the etching paste.
[0068] A method of preparing the etching paste according to an
embodiment may include preparing a binder solution by dissolving
the organic binder in the solvent, adding the cobalt aluminum oxide
to the binder solution, adding any additive(s) to the binder
solution, and reacting the solution with the acid compound and the
nitrogen-containing component that includes one or more of the
amine compound represented by Formula 1 or the ammonium compound
represented by Formula 2.
[0069] Another embodiment provides a method of forming a pattern
using the paste according to an embodiment. FIG. 1 schematically
illustrates a method of forming a pattern according to the present
example embodiment, and FIG. 2 is a flowchart of the method of
forming the pattern according to the present example
embodiment.
[0070] In the example embodiment shown in FIG. 1, an etching target
20 is deposited on a substrate 30, thereby preparing the substrate
30 on which the etching target 20 is deposited (Operation a). In
some embodiments, the etching target may be metal such as aluminum,
indium tin oxide (ITO), antimony tin oxide (ATO), etc. The
deposition may be carried out by vacuum deposition using a metal
target to deposit the object in several angstroms (.ANG.) to
several nanometers (nm).
[0071] Then, the etching paste 10 is printed on the etching target
20 (Operation b). The etching paste 10 may be printed by screen
printing, offset printing, ink-jet printing, coating, etc.
[0072] Then, the printed etching paste 10 may be dried. Drying may
be carried out in a belt type dry oven or a box type dry oven at a
temperature of, e.g., about 100.degree. C. to about 250.degree. C.
Within this temperature range, the paste may allow an etching
function to be exhibited while an acid and a complex are separated.
In an implementation, the drying temperature may range from about
160.degree. C. to about 230.degree. C. After drying, the paste 10
may be left at room temperature for about 5 to about 60
minutes.
[0073] Then, the dried paste may be washed so that the paste is
removed from the substrate and an area where the paste has been
placed is etched, thereby forming a pattern (Operation c). In an
implementation, the paste may be removed by washing with water. In
an implementation, the paste may be removed by a developer using a
developing agent.
[0074] Another embodiment provides a patterned element which
includes a pattern formed using the etching paste. The patterned
element may include a solar cell, an LCD, an OLED, a PDP, etc.
[0075] The following Examples and Comparative Examples are provided
in order to highlight characteristics of one or more embodiments,
but it will be understood that the Examples and Comparative
Examples are not to be construed as limiting the scope of the
embodiments, nor are the Comparative Examples to be construed as
being outside the scope of the embodiments. Further, it will be
understood that the embodiments are not limited to the particular
details described in the Examples and Comparative Examples.
[0076] Etching pastes were prepared using components according to
compositions (unit: % by weight) listed in Table 1.
[0077] Hydroxypropyl cellulose (L-IND, Ashland, Inc.) was dissolved
in distilled water at 0.degree. C. to 5.degree. C. for 2 hours
while stirring at 2,000 rpm and heated to room temperature, and NMP
(Aldrich Co.) was added thereto, thereby preparing an organic
binder solution. Then, silica (A200, Degussa Co.), acetic acid
(Aldrich Co.), and cobalt aluminum oxide (Grade: 5462,
CoAl.sub.2O.sub.4, Average diameter (D50): 0.8 .mu.m, TomaTech
Ltd.) were added to the prepared solution, and a paste was prepared
using a bead-mill or a 3-roll mill. Phosphoric acid (Phosphoric
acid aqueous solution, Concentration: 85%, Aldrich Co.) was added
dropwise to the paste while stirring the paste, followed by
dropwise addition of an ammonia water solution (Concentration: 35%,
Aldrich Co.) or methylamine (Aldrich Co.) and stirring for 3 hours,
thereby producing an etching paste.
[0078] In Comparative Example 2, carbon black (Grade: L600, Ketjen
Black, Mitsubishi Chemical Corp.) was used instead of the cobalt
aluminum oxide.
TABLE-US-00001 TABLE 1 Comparative Example Example 1 2 3 4 1 2 Acid
compound (phosphoric 29.1 27.8 29.1 29.1 29.1 29.1 acid) Organic
binder 9.0 8.6 9.0 9.0 9.0 9.0 Amine or Ammonia 0.4 0.4 -- 0.4 0.4
0.4 ammonium water solution compound Methylamine -- -- 0.4 -- -- --
Cobalt aluminum oxide 10.1 13.9 10.1 1.0 -- -- Additives Silica 2.2
2.2 2.2 2.2 2.2 2.2 Acetic acid 4.5 4.3 4.5 4.5 4.5 4.5 Solvent
Distilled water 33.5 32.1 33.5 42.6 43.6 33.5 NMP 11.2 10.7 11.2
11.2 11.2 11.2 Carbon black -- -- -- -- -- 10.1 Total 100 100 100
100 100 100
[0079] Metal patterns were formed using the etching pastes obtained
in the Examples and Comparative Examples as follows.
[0080] Formation of Metal Pattern
[0081] Each etching paste was printed on an ITO-deposited glass
substrate (PD200, Asahi Glass Co.) using a SUS 400 mesh screen mask
having a pattern of 30 to 150 .mu.m. The substrate was dried in a
belt type dry oven or a box type dry oven while changing
temperature to 100.degree. C., 150.degree. C., or 200.degree. C.
and then left at room temperature for 20 minutes. The applied
etching paste was removed using a developer with a developing agent
of 0.1% sodium carbonate, thereby forming a pattern.
[0082] The formed pattern was evaluated as to printing resolution,
visibility of etching extent, and resistance after etching
(including a picture of the pattern), and results thereof are shown
in FIGS. 3 and 4 and Tables 2 and 3.
[0083] (1) Printing resolution: Each etching paste was printed on
an ITO-deposited glass substrate (PD200, Asahi Glass Co., Ltd.)
through a screen mask having a line width of 30 .mu.m to 200 .mu.m.
Then, disconnection of a pattern or a pattern not intruding into a
non-etched region was expressed by a resolution limit.
[0084] (2) Visibility of etching extent: Each of the etching pastes
was printed using an SUS 400 mesh screen mask having a 50 .mu.m
line-width pattern. The etching pastes were dried for the same
duration in a belt type dry oven or a box type dry oven while
changing temperature to 100.degree. C., 150.degree. C., or
200.degree. C. The substrate was left at room temperature for 20
minutes, followed by photographing an image of the wiring pattern
using a stereoscopic microscope (at a magnification of 1.5 times)
and calculating a ratio of a black area to a blue area using an
image analyzer (Image-Pro). A higher heated area ratio shows a
higher degree of etching.
[0085] (3) Resistance after etching: Resistance of the etched
wiring pattern was measured in a length of 50 mm using a 2-probe
resistance tester (Keyence Co.)
TABLE-US-00002 TABLE 2 Comparative Example Example 1 2 3 4 1 2
Printing resolution 200 200 Not Not Not Not after heat treatment
etched etched etched etched at 100.degree. C. Printing resolution
100 100 200 200 200 200 after heat treatment at 150.degree. C.
Printing resolution 60 50 100 80 150 60 after heat treatment at
200.degree. C.
TABLE-US-00003 TABLE 3 Comparative Example Example 1 2 3 4 1 2 Area
ratio after heat 50 50 20 30 0 100 treatment at 100.degree. C. Area
ratio after heat 75 75 40 70 0 100 treatment at 150.degree. C. Area
ratio after heat 100 100 80 95 0 100 treatment at 200.degree. C.
Resistance (.OMEGA.) after 5,000 .infin. 160 400 200 3,800 etching
@ 200.degree. C., 50 .mu.m
[0086] As shown in Table 2, the etching pastes according to
embodiments may etch with low-temperature heat treatment at
100.degree. C. or 150.degree. C., thereby realizing a fine line
width of 100 .mu.m or greater. On the other hand, the pastes not
including the cobalt aluminum oxide or including the carbon black
provided relatively poor etching properties in the same
low-temperature heat treatment.
[0087] Further, as shown in Table 3, as the temperature of heat
treatment increased, the etching pastes according embodiments had a
gradually increasing ratio of the black area to the blue area,
which was identified with the naked eye, and thus the extent of
etching could be determined based on color change. On the other
hand, the pastes not including the cobalt aluminum oxide or
including the carbon black did not provide comparable effects. In
addition, the etching pastes according to embodiments had a uniform
cross section without etching expansion at a distal end of the
pattern, as shown in FIG. 3. On the other hand, as shown in FIG. 4,
the pastes not including the cobalt aluminum oxide or including the
carbon black did not provide comparable effects.
[0088] By way of summation and review, an etching paste may use an
acid compound. In a pattern forming process using an etching paste
that includes an acid compound, an etching target may be deposited
on a substrate and then the etching paste may be printed thereon
through a mask, dried by heat treatment, and washed, thereby
forming a pattern. When the object is etched through heat
treatment, the extent of etching may not be uniform and may vary
depending on the thickness of the object. Further, a general
etching paste may spread at a distal end of the target object
during heat treatment, which may cause an increase in resistance of
a final pattern. Further, it may be difficult to identify whether
etching is finished by heat treatment. For example, a method of
manufacturing an electrode may include forming a semiconductor unit
having an opposite conductive type to a semiconductor substrate on
the semiconductor substrate, forming a protective film on the
semiconductor unit, printing an etching paste on the protective
film, etching the semiconductor unit, and applying a conductive
metal material. In this method, it may be difficult to recognize
the extent of etching.
[0089] As described above, embodiments may provide an etching paste
that enables an etching extent to be visually perceived. Further,
the etching paste may allow etching at a low drying temperature,
may prevent resistance increase by preventing expansion of etching
at a distal end of a pattern during or after etching, an may
increase etching selectivity (resolution). Further, the etching
paste may help realize a fine line width, may exhibit good etching
performance, and may reduce effects on equipment. Embodiments also
provide a method of preparing the etching paste and a method of
forming a pattern using the etching paste. According to
embodiments, it may be possible to identify whether etching is
finished by heat treatment, and thus pattern formation may be
completed without excess heat treatment. Thus, embodiments may
enable determination of the extent of etching based on temperature
and duration of heat treatment.
[0090] Example embodiments have been disclosed herein, and although
specific terms are employed, they are used and are to be
interpreted in a generic and descriptive sense only and not for
purpose of limitation. In some instances, as would be apparent to
one of ordinary skill in the art as of the filing of the present
application, features, characteristics, and/or elements described
in connection with a particular embodiment may be used singly or in
combination with features, characteristics, and/or elements
described in connection with other embodiments unless otherwise
specifically indicated. Accordingly, it will be understood by those
of skill in the art that various changes in form and details may be
made without departing from the spirit and scope of the present
invention as set forth in the following claims.
* * * * *