U.S. patent application number 13/761338 was filed with the patent office on 2013-08-22 for polishing pad and method of manufacturing the same.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The applicant listed for this patent is KPX CHEMICAL CO., LTD., SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Bong-Su AHN, Jeong-Seon CHOO, Hwi-Kuk CHUNG, Young-Jun JANG, Seung-Geun KIM, Sang-Mok LEE, Jang-Won SEO, Kee-Cheon SONG.
Application Number | 20130212951 13/761338 |
Document ID | / |
Family ID | 48957116 |
Filed Date | 2013-08-22 |
United States Patent
Application |
20130212951 |
Kind Code |
A1 |
AHN; Bong-Su ; et
al. |
August 22, 2013 |
POLISHING PAD AND METHOD OF MANUFACTURING THE SAME
Abstract
Polishing pad and method of manufacturing the same, the method
including: (a) mixing materials for forming a polishing layer; (b)
mixing at least two from among inert gas, a capsule type foaming
agent, a chemical foaming agent, and liquid microelements that are
capable of controlling sizes of pores, with the mixture in (a) so
as to form two or more types of pores; (c) performing gelling and
hardening of the mixture generated in (b) so as to form a polishing
layer including the two or more types of pores; and (d) processing
the polishing layer so as to distribute micropores defined by
opening the two or more types of pores on a surface of the
polishing layer.
Inventors: |
AHN; Bong-Su; (Seoul,
KR) ; JANG; Young-Jun; (Suwon-si, KR) ; LEE;
Sang-Mok; (Seoul, KR) ; CHUNG; Hwi-Kuk;
(Daegu, KR) ; SONG; Kee-Cheon; (Ulsan, KR)
; KIM; Seung-Geun; (Ulsan, KR) ; SEO;
Jang-Won; (Busan, KR) ; CHOO; Jeong-Seon;
(Busan, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KPX CHEMICAL CO., LTD.;
SAMSUNG ELECTRONICS CO., LTD.; |
|
|
US
US |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
KPX CHEMICAL CO., LTD.
Seoul
KR
|
Family ID: |
48957116 |
Appl. No.: |
13/761338 |
Filed: |
February 7, 2013 |
Current U.S.
Class: |
51/296 |
Current CPC
Class: |
B24D 3/34 20130101; B24D
3/32 20130101; B24D 11/003 20130101; B24B 37/24 20130101 |
Class at
Publication: |
51/296 |
International
Class: |
B24D 3/32 20060101
B24D003/32 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 20, 2012 |
KR |
10-2012-0016845 |
Claims
1. A method of manufacturing a polishing pad, the method
comprising: (a) mixing materials for forming a polishing layer; (b)
mixing at least two from among inert gas, a capsule type foaming
agent, a chemical foaming agent, and liquid microelements that are
capable of controlling sizes of pores, with the mixture in (a) so
as to form two or more types of pores; (c) performing gelling and
hardening of the mixture generated in (b) so as to form a polishing
layer comprising the two or more types of pores; and (d) processing
the polishing layer so as to distribute micropores defined by
opening the two or more types of pores on a surface of the
polishing layer.
2. The method of claim 1, wherein the inert gas is selected from
the group consisting of 8 group elements of a periodic table and
gas that does not react with the materials for forming the
polishing layer.
3. The method of claim 1, wherein a liquid material that
constitutes the liquid microelements comprises at least one
selected from the group consisting of aliphatic mineral oil,
aromatic mineral oil, a silicon oil which does not have a hydroxyl
group at the end of molecules, soybean oil, coconut oil, palm oil,
cotton seed oil, camellia oil, hardened oil, or a combination
thereof.
4. A polishing pad that performs a polishing process by moving in
contact with a surface of an object to be polished, the polishing
pad comprising a polishing layer, wherein the polishing layer
comprises two or more types of pores, of which sizes are controlled
by using at least two from among inert gas, a capsule type foaming
agent, a chemical agent, and liquid microelements, and micropores
that are defined by opening the two or more types of pores are
distributed on a surface of the polishing layer.
5. The polishing pad of claim 4, wherein the inert gas is selected
from the group consisting of 8 group elements of a periodic table
and gas that does not react with the materials for forming the
polishing layer.
6. The polishing pad of claim 4, wherein a liquid material that
constitutes the liquid microelements comprises at least one
selected from the group consisting of aliphatic mineral oil,
aromatic mineral oil, a silicon oil which does not have a hydroxyl
group at the end of molecules, soybean oil, coconut oil, palm oil,
cotton seed oil, camellia oil, hardened oil, or a combination
thereof.
7. The polishing pad of claim 4, wherein the polishing layer
comprises a plurality of first pores formed by the liquid
microelements and a plurality of second pores having a relatively
large size and formed by using at least one from among injecting
the inert gas, injecting the capsule type foaming agent, and
injecting the chemical foaming agent.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a polishing pad and a
method of manufacturing the same, and more particularly, to a
polishing pad that allows a polishing slurry to be effectively
collected and supplied and a method of manufacturing the same.
[0003] 2. Description of the Related Art
[0004] A chemical mechanical planarization/polishing (CMP) process
has been used for global planarization of semiconductor devices and
has become important with tendencies to an increase in the diameter
of a wafer, a high integration density, a micro line width, and a
multilayer wiring structure.
[0005] In a CMP process, a polishing speed and the flatness of a
wafer are important, and the performance of such a CMP process
depends on conditions of CMP equipment and performances of a
polishing slurry and a polishing pad that are consumable members.
In particular, the polishing pad allows the polishing slurry
supplied in a state where the polishing pad is in contact with the
surface of the wafer, to be uniformly dispersed onto the wafer so
that physical abrasion is provoked by abrasive particles contained
in the polishing slurry and protrusions of the polishing pad.
[0006] In this case, a polishing pad's surface directly contacting
the wafer needs to be saturated with the polishing slurry so that
the polishing slurry flows smoothly. To this end, techniques for
forming micro holes (for example, pores) in the polishing pad's
surface are disclosed in U.S. Pat. No. 5,578,362 and the like.
[0007] In this way, it is very important to maintain the polishing
pad's surface to be saturated with the polishing slurry so as to
increase the role and performance of the polishing pad in the CMP
process. Thus, grooves in various shapes are formed in the
polishing pad so as to form a large slurry flow, and micro holes
are formed in the polishing pad's surface by opening a microporous
material, as described above.
[0008] Among them, techniques for forming grooves in various
patterns have been developed; however, techniques relating to a
plurality of pores for forming micro holes are limited to
restrictively using methods of forming predetermined pores.
[0009] That is, there are advantages and disadvantages depending on
methods of forming a plurality of pores according to the related
art. In actuality, the CMP process is used by adjustment in
consideration of the advantages and disadvantages.
[0010] However, as a semiconductor process is required to be more
minute and more elaborate, the CMP process also requires an
improved technique for forming a plurality of pores so as to
satisfy the demand.
SUMMARY OF THE INVENTION
[0011] The present invention provides a polishing pad that may
maximize polishing performance and planarization performance by
collecting and using a polishing slurry when a chemical mechanical
planarization/polishing (CMP) process is performed and a method of
manufacturing the same.
[0012] According to an aspect of the present invention, there is
provided a polishing pad that performs a polishing process by
moving in contact with a surface of an object to be polished, the
polishing pad including a polishing layer, wherein the polishing
layer comprises two or more types of pores, of which sizes are
controlled by using at least two from among inert gas, a capsule
type foaming agent, a chemical agent, and liquid microelements, and
micropores that are defined by opening the two or more types of
pores are distributed on a surface of the polishing layer.
[0013] According to another aspect of the present invention, there
is provided a method of manufacturing a polishing pad, the method
including: (a) mixing materials for forming a polishing layer; (b)
mixing at least two from among inert gas, a capsule type foaming
agent, a chemical foaming agent, and liquid microelements that are
capable of controlling sizes of pores, with the mixture in (a) so
as to form two or more types of pores; (c) performing gelling and
hardening of the mixture generated in (b) so as to form a polishing
layer comprising the two or more types of pores; and (d) processing
the polishing layer so as to distribute micropores defined by
opening the two or more types of pores on a surface of the
polishing layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The above and other features and advantages of the present
invention will become more apparent by describing in detail
exemplary embodiments thereof with reference to the attached
drawings in which:
[0015] FIG. 1 is a cross-sectional view of a polishing pad
according to an embodiment of the present invention;
[0016] FIG. 2 is an enlarged scanning electron microscope (SEM)
photograph of a cross-section of a polishing layer of the polishing
pad illustrated in FIG. 1;
[0017] FIG. 3 is a schematic diagram of a polishing apparatus
employing the polishing pad of FIG. 1;
[0018] FIG. 4 is a flowchart illustrating a method of manufacturing
the polishing layer of the polishing pad according to an embodiment
of the present invention;
[0019] FIGS. 5 and 6 are SEM photographs of pores formed in the
surface of a polishing layer including pores formed by inert gas
and pores formed by liquid microelements, according to an
embodiment of the present invention; and
[0020] FIG. 7 illustrates comparison of the polishing efficiency of
a polishing pad formed by using methods (Experimental Examples 2
and 3) according to the present invention with the polishing
efficiency of a polishing pad formed according to the related
art.
DETAILED DESCRIPTION OF THE INVENTION
[0021] As used herein, the term "and/or" includes any and all
combinations of one or more of the associated listed items.
[0022] The present invention will now be described more fully with
reference to the accompanying drawings, in which exemplary
embodiments of the invention are shown.
[0023] FIG. 1 is a cross-sectional view of a polishing pad 100
according to an embodiment of the present invention, FIG. 2 is an
enlarged scanning electron microscope (SEM) photograph of a
cross-section of a polishing layer 120 of the polishing pad 100
illustrated in FIG. 1, and FIG. 3 is a schematic diagram of a
polishing apparatus 1 employing the polishing pad 100 of FIG.
1.
[0024] Referring to FIG. 1, the polishing pad 100 according to the
current embodiment of the present invention includes a support
layer and a polishing layer 120. The support layer is used to fix
the polishing pad 100 to a platen 3, as shown in FIG. 3. The
support layer is made of a material having stability in order to
correspond to a force pressing a silicon wafer 7, i.e., an object
to be polished, which is loaded at a head 5 facing the platen 3 so
that the support layer supports the polishing layer 120 formed on
the support layer with uniform elasticity with respect to the
silicon wafer 7. Accordingly, the support layer is made of a
nonporous, solid, and uniform elastic material mainly and has lower
hardness than the polishing layer 120 formed on the support
layer.
[0025] In addition, at least a part of the support layer is
transparent or semitransparent so that a light beam 170 used to
detect the flatness of a surface of the object to be polished can
be transmitted through the support layer. In FIG. 3, the object to
be polished is the silicon wafer 7 having a metal or insulation
layer as a layer to be polished. However, various types of
substrates such as a substrate, on which a thin film
transistor-liquid crystal display (TFT-LCD) is to be formed, a
glass substrate, a ceramic substrate, and a polymer plastic
substrate may be objects to be polished. In addition, the polishing
pad 100 can be manufactured without including the support
layer.
[0026] Also, although the polishing pad 100 has a circular shape so
as to be suitable for the rotation type polishing apparatus 1, as
shown in FIG. 3, the polishing pad 100 can be modified in various
shapes, such as a rectangular shape, a square shape, and the like,
according to the shape of the polishing apparatus 1.
[0027] As shown in FIG. 3, the polishing layer 120 directly
contacts the silicon wafer 7 as the object to be polished. The
polishing layer 120 can be formed by mixing or chemically combining
predetermined materials for forming a polishing layer. That is, a
polymeric matrix 130 that constitutes the polishing layer 120 is
composed of various well-known components, and descriptions of
well-known materials and forming materials will be omitted.
[0028] The polishing layer 120 may include two or more types of a
plurality of pores. The sizes of two or more types of the plurality
of pores are controlled by at least two selected from the group
consisting of inert gas, a capsule type foaming agent, a chemical
foaming agent, and liquid microelements.
[0029] That is, types of pores can be distinguished from each other
by a method of forming the pores. At least two types of pores
selected from the group consisting of pores formed by the inert
gas, pores formed by the capsule type foaming agent, pores formed
by the chemical foaming agent, and pores formed by the liquid
microelements are included in the polishing layer 120 according to
the present invention.
[0030] Here, pores according to their types may be formed so that
their sizes are distinguished from one another; however, aspects of
the present invention are not limited thereto.
[0031] Hereinafter, as an example of the present invention, it is
assumed that two types of a plurality of pores, i.e., a plurality
of first pores and a plurality of second pores are formed in the
polishing layer 120 and in particular, the plurality of first pores
therebetween are formed by the liquid microelements and the
plurality of second pores are formed by the inert gas.
[0032] In this way, when the plurality of first pores formed by the
liquid microelements are included in the polishing layer 120, a
material formed by mixing the materials for forming the polishing
layer as described above may correspond to a hydrophilic polymeric
matrix containing polyalkylene glycol (hereinafter, referred to as
a `polyalkylene glycol-containing hydrophilic polymeric matrix`)
130.
[0033] That is, the polishing layer 120 may include a plurality of
first pores 141 formed of embedded liquid microelements and a
plurality of second pores 142 that are gaseous pores including
embedded inert gas, which are uniformly distributed in
predetermined regions of the polyalkylene glycol-containing
hydrophilic polymeric matrix 130.
[0034] An actual example of the plurality of first pores (liquid
microelement pores) 141 and the plurality of second pores (gaseous
pores) 142 included in the polishing layer 120 in this manner is as
shown in FIG. 2.
[0035] A plurality of micropores 141' and 142', which have an open
microstructure and are defined by the plurality of first pores 141
and the plurality of second pores 142, are uniformly arranged in a
polishing layer surface 160, which directly contacts a silicon
wafer 7.
[0036] Here, the plurality of micropores 141' and 142', which have
an open microstructure and are defined by the plurality of first
pores 141 and the plurality of second pores 142, means that, as the
liquid microelements or inert gas embedded in the polishing layer
120 leak or leaks to the outside, regions in which the liquid
microelements or inert gas are or is included, remain from the
micropores 141' and 142' so that predetermined materials from the
outside can be collected in the regions.
[0037] The plurality of first and second pores 141 and 142 that are
embedded as the polishing pad 100 is abraded during a polishing
process, are continuously exposed to the polishing layer surface
160 and form the micropores 141' and 142', and the micropores 141'
and 142' are substituted by a polishing slurry 13. Thus, since only
the polymeric matrix 130 exists in the polishing layer surface 160,
non-uniform abrasion of the polishing pad 100 does not occur but
the silicon wafer 7 as an object to be polished can be uniformly
polished.
[0038] The polyalkylene glycol-containing hydrophilic polymeric
matrix 130 may be formed of a material that is not dissolved in the
polishing slurry 13 as a chemical solution used for planarization.
For example, as shown in FIG. 3, the polyalkylene glycol-containing
hydrophilic polymeric matrix 130 is formed of a material into which
the polishing slurry 13 supplied through a nozzle 11 of the
polishing apparatus 1 cannot infiltrate.
[0039] The polyalkylene glycol-containing hydrophilic polymeric
matrix 130 may be formed by chemically combining or physically
mixing a material for forming a polymeric matrix, a hydrophilic
material, and a polyalkylene glycol compound.
[0040] Here, the polymeric matrix 130 formed by the material for
forming a polymeric matrix may be formed of one material selected
from the group consisting of polyurethane, polyether, polyester,
polysulfone, polyacryl, polycarbonate, polyethylene,
polymethylmetacrylate, polyvinylacetate, polyvinylchloride,
polyethyleneimine, polyethersulfone, polyetherimide, polyketone,
melamine, nylon, hydrocarbon fluoride, or a combination
thereof.
[0041] The polyalkylene glycol-containing hydrophilic polymeric
matrix 130 is formed by chemically combining or physically mixing
the hydrophilic material and the polyalkylene glycol compound with
the polymeric matrix 130.
[0042] The hydrophilic material may be one selected from the group
consisting of polyethylene glycol, polyethylenepropylene glycol,
polyoxyethylene alkylphenolether, polyoxyethylene alkylether,
polyethylene glycol fatty acid ester, polyoxyethylene alkylamine
ether, glycerine fatty acid ester, sugar fatty acid ester, sorbitol
fatty acid ester, or a combination thereof.
[0043] The polyalkylene glycol compound may be one selected from
the group consisting of compounds in which alkylene oxide is added
to a compound including water or active hydrogen, or a combination
thereof.
[0044] The above-described materials for forming the polishing
layer 120 may include various materials apart from the materials
described above.
[0045] The embedded liquid microelements that form the first pores
141 are formed of a liquid material that is not compatible with the
polyalkylene glycol-containing hydrophilic polymeric matrix 130,
i.e., a material selected from the group consisting of aliphatic
mineral oil, aromatic mineral oil, a silicon oil which does not
have a hydroxyl group at the end of molecules, soybean oil, coconut
oil, palm oil, cotton seed oil, camellia oil, hardened oil, or a
combination thereof.
[0046] The first pores 141 formed by the embedded liquid
microelements may be dispersed into the polyalkylene
glycol-containing hydrophilic polymeric matrix 130 in a micro
spherical shape. The average diameter of spheres may be between 1
to 30 .mu.m, for example, between 2 to 10 .mu.m. The diameter of
spheres in the above range is most optimal to the collection and
supply of the polishing slurry 13. However, the diameter of spheres
can be changed depending on a type of the polishing slurry 13, and
the size of the embedded liquid microelements 141 can be also
changed.
[0047] The shape of the first pores 141 formed by the embedded
liquid microelements, i.e., the average diameter and concentration
of spheres, can be easily and variously adjusted by a change of a
degree of a hydrophilic property of the polyalkylene
glycol-containing hydrophilic polymeric matrix 130.
[0048] In addition, the shape of the first pores 141 formed by the
embedded liquid microelements can be easily and variously adjusted
by parts by weight of a liquid material based on 100 parts by
weight of a material for forming the polymeric matrix. For example,
20 to 50 parts by weight, more preferably, 30 to 40 parts by weight
based on 100 parts by weight of the material for forming the
polymeric matrix, i.e., based on 100 parts by weight of
polyurethane is used in order to form the first pores 141 by a
desired shape of the embedded liquid microelements.
[0049] The sizes and concentrations of the first pores 141 formed
by the embedded liquid microelements and the micropores 141'
defined by the first pores 141 can be variously adjusted by the
degree of the hydrophilic property of the polyalkylene
glycol-containing hydrophilic polymeric matrix 130 and/or the
amount of the liquid material. Thus, the polishing pad 100 having
various polishing performances can be manufactured according to a
type of an object to be polished and/or a type of the polishing
slurry 13.
[0050] The second pores 142 are formed by injecting inert gas, a
capsule type foaming agent, or a chemical foaming agent.
[0051] Here, the inert gas may be gas having a valence of 0 that is
chemically stable, i.e., helium (He), neon (Ne), argon (Ar),
krypton (Kr), xenon (Xe), or radon (Rn). Furthermore, the inert gas
may be any gas that does not react with a polymeric matrix, i.e.,
that does not participate in a urethane reaction, such as N.sub.2,
apart from 8 group elements of the periodic table.
[0052] The foaming agent that is mixed with a predetermined
material and generates a large amount of bubbles by evaporation or
reaction by heat, can be largely classified into a chemical foaming
agent and a physical foaming agent.
[0053] In the chemical foaming agent, foaming occurs in carbon
dioxide that is generated by a reaction with water by using
vitality of an isocyanate group, and thus water is used for a
foaming agent. In the physical foaming agent, bubbles are formed by
generating reaction heat by injecting gas or using a decomposable
or evaporative foaming agent, and thus, the physical foaming agent
does not participate in a polymer reaction. Types and features of
these foaming agents are already well-known and thus, detailed
descriptions thereof will be omitted.
[0054] The second pores 142 are formed on the polishing layer 120
by mixing the inert gas or various foaming agents (capsule type
foaming agent or chemical foaming agent). The second pores 142 may
have a larger radius than that of the first pores 141. Preferably,
the second pores 142 are formed to have a volume corresponding to
10 times a volume of the first pores 141.
[0055] Hereinafter, a method of manufacturing the polishing layer
120 of the polishing pad 100 according to an embodiment of the
present invention will be described with reference to FIG. 4.
[0056] First, materials for forming the polishing layer 120 are
mixed (S100). In detail, the above-described material for forming
the polyalkylene glycol-containing hydrophilic polymeric matrix 130
may be mixed with the materials for forming the polishing layer 120
(S100).
[0057] Here, the material for forming the polyalkylene
glycol-containing hydrophilic polymeric matrix 130 is generated by
mixing or reacting a hydrophilic material and a polyalkylene glycol
compound with a material for forming a polymeric matrix. The mixing
or reaction may be performed by stirring.
[0058] In the mixing process, a liquid material, such as mineral
oil, is together mixed with the material for forming the polymeric
matrix. In this case, inert gas (or a predetermined foaming agent
that replaces the inert gas), such as Ar, may be injected.
[0059] Amounts of the mixed liquid material and the insert gas can
be adjusted according to the sizes of pores to be formed depending
on types.
[0060] Subsequently, gelling and hardening are performed (S510).
That is, the mixture is injected into a cast having a predetermined
shape and then solidified through gelling and hardening. Gelling is
performed for 5 to 30 minutes at 80 to 90.degree. C., and hardening
is performed for 20 to 24 hours at 80 to 120.degree. C.. However,
processing temperature and time can be variously changed to provide
optimal conditions.
[0061] Last, the resultant structure of the hardening, having the
predetermined shape, is processed (S520). The resultant structure
is processed through taking off the cast, cutting, surface
treatment, and cleaning. First, the hardened resultant structure is
taken out of the cast and cut to have a predetermined thickness and
shape. It is apparent that the polishing layer 120 can be formed in
the shape of sheet using any method, such as casting or extrusion,
known in the field of polymer sheet manufacturing in order to
increase the productivity. Grooves in various shapes may be formed
in a surface of the polishing layer 120 so that the polishing
slurry 13 can be uniformly supplied across the working surface of
the polishing layer 120.
[0062] After a cleaning process is performed, the polishing layer
120 is completed. During the cleaning process, embedded liquid
microelements 141 exposed at the surface of the polishing layer 120
flow out, and thus open micropores 141' are distributed on the
polishing layer surface 160. Here, a liquid cleanser may be used to
remove the embedded liquid microelements 141 from the polishing
layer surface 160.
[0063] The polishing pad 100 can be constituted only by the
polishing layer 120. However, when necessary, the support layer can
be made using a method widely known in the field of manufacturing
the polishing pad 100 and is combined with the polishing layer 120
to complete the polishing pad 100.
[0064] More details of the present invention will be described by
explaining specific experimental examples. Details not described
below are omitted because they can be technically inferred by those
skilled in the art. It will be apparent that the scope of the
present invention is not limited to the following experimental
examples.
Experimental Example 1
[0065] 50 kg of polytetramethylene glycol (having a molecular
weight of 1000), 50 kg of polyethylene glycol (having a molecular
weight of 1000), and 52 kg of toluendiisocyanate were put into 200
kg of a reactor, were made to react with one another for 4 to 5
hours at 70 to 80.degree. C. so that the NCO content of a final
product was 11.0%. The viscosity of the manufactured isocyanate
prepolymer was 6,900 cPs (25.degree. C.).
Experimental Example 2
[0066] 100 kg of the isocyanate prepolymer manufactured in
Experimental Example 1, 46 kg of mineral oil (hereinafter, referred
to as KF-70)(manufactured by the Seojin Chemical Co., Ltd.), and 33
kg of MOCA were ejected using a casting machine after undergoing a
mixing head at 5000 rpm. In this case, inert gas, i.e., Ar gas was
put in the mixing head at 10% of a volumetric ratio.
[0067] Thereafter, the mixture was immediately injected into a
rectangular cast. Then, gelling was performed for 30 minutes, and
thereafter, hardening was performed in an oven for 20 hours at
100.degree. C.
[0068] The hardened mixture was taken out of the cast, and the
surface of the hardened mixture was cut to form a polishing layer
of a polishing pad.
[0069] A scanning electron microscope (SEM) photograph of pores
formed on a surface of the polishing layer is shown in FIG. 5.
[0070] Polishing performance and planarization performance of the
manufactured polishing pad are shown in FIG. 7 (the polishing pad
according to the present embodiment is referred to as "hybrid pore
1").
Experimental Example 3
[0071] 100 kg of the isocyanate prepolymer manufactured in
Experimental Example 1, 46 kg of mineral oil (hereinafter, referred
to as KF-70)(manufactured by the Seojin Chemical Co., Ltd.), and 33
kg of MOCA were ejected using a casting machine after undergoing a
mixing head at 5000 rpm. In this case, inert gas, i.e., Ar gas was
put in the mixing head at 20% of a volumetric ratio.
[0072] Thereafter, the mixture was immediately injected into a
rectangular cast. Then, gelling was performed for 30 minutes, and
thereafter, hardening was performed in an oven for 20 hours at
100.degree. C.
[0073] The hardened mixture was taken out of the cast, and the
surface of the hardened mixture was cut to form a polishing layer
of a polishing pad.
[0074] A scanning electron microscope (SEM) photograph of pores
formed on a surface of the polishing layer is shown in FIG. 6.
[0075] Polishing performance and planarization performance of the
manufactured polishing pad are shown in FIG. 7 (the polishing pad
according to the present embodiment is referred to as "hybrid pore
2"). "Solid-state capsule pore" in FIG. 7 represents a polishing
pad that does not use different types of composite pores (i.e.,
first pores and second pores) as in the present invention but uses
only a single solid-state capsule pore (here, the solid-state
capsule may represent hollow micropowder), and "liquid microelement
pore" in FIG. 7 also represents a polishing pad that does not use
different types of composite pores (i.e., first pores and second
pores) as in the present invention but includes only a single
liquid microelement.
[0076] When composite pores having different sizes are used, first
pores having a relatively small size collect a small amount of
polishing slurry particles so that precise polishing can be
performed, and second pores having a relatively large size collect
a large amount of polishing slurry particles at one time so that
processing at high polishing speed can be performed.
[0077] In this way, different types of pores are simultaneously
included in the polishing layer of the polishing pad so that a more
elaborate polishing work can be carried out.
[0078] In the above-described embodiments, two types of pores are
formed. However, aspects of the present invention are not limited
thereto, as described above.
[0079] That is, a polishing pad according to the present invention
may include three or more types of pores from among pores formed by
liquid microelements, pores formed by a solid-state capsule, pores
formed by injecting inert gas, and pores formed by a chemical
foaming agent. The sizes of pores depending on types may be as
described above or can be changed according to types of materials
for forming pores or in order to increase polishing efficiency.
[0080] In particular, in a method of forming pores, the sizes of
pores can be controlled by concentration or reaction temperature of
a mixed material, and pores according to types may not necessarily
have different sizes.
[0081] As described above, according to the present invention,
multiple (double) pores (not a single pore) are controlled so that
slurry collection and supply can be effectively performed and more
improved CMP polishing performance can be achieved. This enables an
elaborate CMP process required by a minute semiconductor
process.
[0082] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
* * * * *