U.S. patent application number 13/555868 was filed with the patent office on 2012-11-29 for polishing pad and method of producing the same.
This patent application is currently assigned to San Fang Chemical Industry Co., Ltd.. Invention is credited to CHEN-HSIANG CHAO, CHUNG-CHIH FENG, YUNG-CHANG HUNG, I-PENG YAO.
Application Number | 20120302142 13/555868 |
Document ID | / |
Family ID | 47219525 |
Filed Date | 2012-11-29 |
United States Patent
Application |
20120302142 |
Kind Code |
A1 |
FENG; CHUNG-CHIH ; et
al. |
November 29, 2012 |
POLISHING PAD AND METHOD OF PRODUCING THE SAME
Abstract
The present invention mainly relates to a polishing pad and
method of producing the same. The polishing pad comprises a base
material having a surface for polishing a substrate, wherein the
surface comprises a plurality of bundles of first long fibers and
an elastomer embedded into the bundles. The bundles of first long
fibers are entangled with each other.
Inventors: |
FENG; CHUNG-CHIH; (Kaohsiung
City, TW) ; YAO; I-PENG; (Kaohsiung City, TW)
; CHAO; CHEN-HSIANG; (Kaohsiung City, TW) ; HUNG;
YUNG-CHANG; (Kaohsiung City, TW) |
Assignee: |
San Fang Chemical Industry Co.,
Ltd.
Kaohsiung City
TW
|
Family ID: |
47219525 |
Appl. No.: |
13/555868 |
Filed: |
July 23, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12883509 |
Sep 16, 2010 |
|
|
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13555868 |
|
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Current U.S.
Class: |
451/59 ; 451/532;
51/298 |
Current CPC
Class: |
B24B 37/24 20130101;
B24D 3/22 20130101; B24D 11/02 20130101; D04H 3/12 20130101; D04H
3/011 20130101; D04H 3/105 20130101 |
Class at
Publication: |
451/59 ; 451/532;
51/298 |
International
Class: |
B24D 11/00 20060101
B24D011/00; B24D 3/28 20060101 B24D003/28; B24B 1/00 20060101
B24B001/00 |
Claims
1. A polishing pad comprising a base material having a surface for
polishing a substrate, wherein the surface comprises a plurality of
bundles of first long fibers and an elastomer embedded into the
bundles, and the bundles of first long fibers are entangled with
each other.
2. The polishing pad according to claim 1, wherein the bundles of
first long fibers are randomly entangled with each other.
3. The polishing pad according to claim 1, wherein the bundles of
first long fibers are oriented in a predetermined direction.
4. The polishing pad according to claim 1, wherein the bundles of
first long fibers are parallel to the surface for polishing a
substrate.
5. The polishing pad according to claim 1, wherein the bundles of
first long fibers comprise a first bundle and a second bundle, and
the first bundle is surrounded by the second bundle.
6. The polishing pad according to claim 5, wherein the first bundle
comprises a first part, and the first part is parallel to each
other; the second bundle comprises a second part placed between the
first parts; and the second part is vertical to the first
parts.
7. The polishing pad according to claim 1, wherein the first long
fiber is selected from the group consisting of a single fiber and
composite fibers.
8. The polishing pad according to claim 1, wherein the first long
fiber is made of at least one material selected from the group
consisting of polyamide, terephthalamide, polyester, polymethyl
methacrylate, polyethylene terephthalate, polyacrylonitrile, and
mixtures thereof.
9. The polishing pad according to claim 1, wherein the length of
the first long fiber is more than about 10 cm.
10. The polishing pad according to claim 1, wherein the first long
fiber is a sea-island fiber.
11. The polishing pad according to claim 1, wherein the base
material further comprises a fiber mat comprising meshes, and the
fiber mat comprises second long fibers, and the second long fibers
and the first long fibers are intertwined with each other.
12. The polishing pad according to claim 1, wherein the elastomer
is a foam resin.
13. A polishing system comprising: a polishing pad according to
claim 1; a substrate to be polished; a slurry, wherein the slurry
together with the polishing pad react chemically with the surface
of the substrate to be polished; wherein the first long fibers and
the elastomer have the functions of carrying the slurry and
removing the reacted surface of the substrate to be polished in a
polishing process.
14. A method of polishing a substrate, the method comprising a step
of using the polishing pad according to claim 1 to polish a surface
of the substrate.
15. A method of producing the polishing pad according to claim 1,
comprising steps of: (a) providing a base material having a surface
for polishing a substrate, wherein the surface comprises a
plurality of bundles of first long fibers, and the bundles of first
long fibers are entangled with each other; (b) impregnating the
surface of the base material with an elastomer solution; and (c)
curing the elastomer impregnated in the surface of the base
material.
16. The method according to claim 15, further comprising a step
(c1) of washing the surface of the base material after the step
(c).
17. The method according to claim 16, further comprising a step
(c2) of drying the surface of the base material after the step
(c1).
18. The method according to claim 15, further comprising a step
(c3) of mechanically polishing the surface of the base material and
the elastomer after the step (c).
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation-in-part of the pending
U.S. patent application Ser. No. 12/883,509 filed on Sep. 16, 2010,
all of which is hereby incorporated by reference in its
entirety.
[0002] Although incorporated by reference in its entirety, no
arguments or disclaimers made in the parent application apply to
this CIP application. Any disclaimer that may have occurred during
the prosecution of the above-referenced application(s) is hereby
expressly rescinded. Consequently, the Patent Office is asked to
review the new set of claims in view of the entire prior art of
record and any search that the Office deems appropriate.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates to a polishing pad for use in
a chemical mechanical polishing, and a method of producing the
polishing pad.
[0005] 2. Description of the Related Art
[0006] Chemical mechanical polishing (CMP) is a procedure for
planarizing the surface of a substrate with a polishing pad. CMP is
generally applied to polishing lens, mirrors, substrates of liquid
crystal displays, silicon wafers, and oxidation and/or metal layers
on silicon wafers.
[0007] Taking silicon wafers as an example, ingots of
monocrystalline silicon are sliced first. The wafers are usually
lapped to make them flat for subsequently chemical etching. A
polishing process is required after the etching process. During the
polishing process, a polishing pad together with slurry reacts
chemically with the silicon atoms on the surface of the wafer to
make the reacted surface softer than the underlying silicon.
Furthermore, the reacted surface is continually wiped away causing
fresh silicon to be exposed to the slurry and the polishing
pad.
[0008] As shown in FIG. 1, a conventional polishing pad comprises a
base material having a surface for polishing a substrate. The
surface comprises fabric and an elastomer embedded into the fabric.
Fibers of the fabric along with the elastomer have the functions of
carrying the slurry and removing the reacted surface from the wafer
in the polishing process. The nonwoven fabric is commonly used in
the base material. A conventional nonwoven fabric uses directional
or non-directional short fibers (usually having a length of less
than 10 cm) for forming fabric without weaving. According to the
manner of forming the fabric, the nonwoven fabric usually comprises
composite nonwoven fabric, needle-punched nonwoven fabric,
melt-blown nonwoven fabric, spunbonded nonwoven fabric, dry-laid
nonwoven fabric, wet-laid nonwoven fabric, stitch bonded nonwoven
fabric, and spunlace nonwoven fabric. However, the short fibers
should be made through a cording process, and a needle-punching
process is also needed when manufacturing needle-punched nonwoven
fabric. Such processes result in an uneven distribution of the
fibers, and aggregations of fibers are easily observed in a
nonwoven fabric. In addition, a breakage of the fibers also occurs
due to these processes. Furthermore, after embedding the elastomer
into the fabric, the uneven distribution of the elastomer due to
the uneven distribution of the fibers affects the cell size made of
the fibers and the elastomer, hardness, uniformity, density of the
elastomer, and thickness, and the slurry cannot flow smoothly and
polishing particles in the slurry cannot diffuse evenly. Balling is
commonly observed when polishing. Besides, the residues formed
during polishing tend to stay on the surface of the polishing pad
and their removal is difficult; as a result, the residues scrape
and damage the substrate to be polished.
SUMMARY OF THE INVENTION
[0009] One object of the present invention is to provide a
polishing pad comprising a base material having a surface for
polishing a substrate, wherein the surface comprises a plurality of
bundles of first long fibers and an elastomer embedded into the
bundles. The bundles of first long fibers are entangled with each
other.
[0010] Another object of the present invention is to provide a
polishing system comprising: [0011] a polishing pad as mentioned
above; [0012] a substrate to be polished; [0013] a slurry, wherein
the slurry together with the polishing pad react chemically with
the surface of the substrate to be polished; [0014] wherein the
first long fibers and the elastomer have the functions of carrying
the slurry and removing the reacted surface of the substrate to be
polished in a polishing process.
[0015] Another object of the present invention is to provide a
method of polishing a substrate. The method comprises a step of
using the polishing pad mentioned above to polish a surface of the
substrate.
[0016] Still another object of the present invention is to provide
a method of producing the polishing pad described above. The method
comprises steps of: (a) providing a base material having a surface
for polishing a substrate, wherein the surface comprises a
plurality of bundles of first long fibers and the bundles of first
long fibers are entangled with each other; (b) impregnating the
surface of the base material with an elastomer solution; and (c)
curing the elastomer impregnated in the surface of the base
material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 shows a view under a transmission electron microscope
of the conventional polishing pad.
[0018] FIG. 2 shows a view under a transmission electron microscope
of the polishing pad according to the second embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] The present invention provides a polishing pad comprising a
base material having a surface for polishing a substrate, wherein
the surface comprises a plurality of bundles of first long fibers
and an elastomer embedded into the bundles. The bundles of first
long fibers are entangled with each other.
[0020] In the first embodiment of the invention, the bundles of
first long fibers are randomly entangled with each other. Such base
material usually comprises non-woven fabric. As used herein,
"non-woven fabric" refers to a manufactured sheet, web or mat of
directionally or randomly orientated fibers, bonded by friction,
and/or cohesion and/or adhesion, excluding paper and products which
are woven, knitted, tufted, stitch-bonded incorporating binding
yarns or filaments, or felted by wet-milling, whether or not
additionally needled. The fibers may be of natural or man-made
origin. They may be staple or continuous filaments or be formed in
situ. According to the method of forming the web, the non-woven
fabric usually comprises composite nonwoven fabric, needle-punched
nonwoven fabric, melt-blown nonwoven fabric, spunbonded nonwoven
fabric, dry-laid nonwoven fabric, wet-laid nonwoven fabric, stitch
bonded nonwoven fabric, and spunlace nonwoven fabric. Compared with
woven fabric, the non-woven fabric has a better material
property.
[0021] In one embodiment of the invention, the bundle of first long
fibers according to the invention twist together, entwine into a
confusing mass and are snarled. On the contrary, the conventional
short fibers only distribute randomly without entangling with each
other and without twist together.
[0022] In the second embodiment of the invention, the bundles of
first long fibers are oriented in a predetermined direction as
shown in FIG. 2. As used herein, "a predetermined direction" refers
to any given orientation of the bundles of first long fibers.
Compared to the random distribution of the bundles of first long
fibers as described in the first embodiment, the predetermined
direction is planned in advance. Such base material usually
comprises woven fabric.
[0023] Preferably, the bundles of first long fibers are parallel to
the surface for polishing a substrate.
[0024] Preferably, the bundles of first long fibers comprise a
first bundle and a second bundle, and the first bundle is
surrounded by the second bundle. Moreover, the first bundle is
partially or totally surrounded by the second bundle.
[0025] More preferably, the first bundle comprises a first part,
and the first part is parallel to each other; the second bundle
comprises a second part placed between the first parts; and the
second part is vertical to the first parts.
[0026] In one preferred embodiment of the invention, the base
material is used in a roll-to-roll manner that improves batch
uniformity.
[0027] As used herein, the term "fiber" refers to a single fiber or
composite fibers, preferably composite fibers. The fiber is
selected in accordance with the substrate to be polished. The
fibers of the surface of the base material provide protrusions for
polishing and also provide a scaffold allowing the elastomers
deposed in the space defined by the scaffold. Artisans skilled in
this field can choose suitable kinds of fibers and coordinate the
elastomer polymer with the fibers according to the disclosure of
the specification. Preferably, the first long fiber is made of at
least one material selected from the group consisting of polyamide,
terephthalamide, polyester, polymethyl methacrylate, polyethylene
terephthalate, polyacrylonitrile, and mixtures thereof.
[0028] As defined in this field, the term "long fiber" refers to a
fiber having a length more than about 10 cm. The shape of the long
fiber is continuous and the length is unlimited in theory. The long
fiber is easily twisted for improving the strength and stress.
[0029] In one preferred embodiment of the invention, the fiber is a
sea-island fiber. As used herein, the term "sea-island fiber," also
known as "sea-island type composite fiber," refers to a fiber
comprising a sea component and an island component. For example,
the sea-island fiber is produced by conjugate-spinning or
blend-spinning two polymers in a sea-island manner In one preferred
embodiment of the invention, the sea-island fiber is treated by
weight reducing to reduce the proportion of the sea component. The
methods of weight reducing the sea component are well known to
artisans skilled in this field, such as those methods using sodium
hydroxide or toluene. Preferably, the long fiber after reducing the
sea component is divided into 0.05 to 0.0001 Deniers.
[0030] In one preferred embodiment of the invention, the base
material comprises a fiber mat. As used herein, the term "fiber
mat" refers to a thin and strengthened material designed for
improving the strength of the fibers according to the invention.
The material of the fiber mat is preferably polyamide, polyester,
or polyolefin. The fiber mat preferably comprises second long
fibers. The second long fibers can be woven or non-woven to form
the fiber mat. The fiber mat comprises meshes, and the second long
fibers of the fiber mat and the first long fibers are intertwined
with each other. Preferably, the fiber mat has a thickness of 0.01
to 1.0 mm. The fiber mat has a weight per area unit of 10 to 200
g/m.sup.2. In addition, the fiber mat has a mesh of 10 to 150.
[0031] As used herein, the term "elastomer," also known as "elastic
polymer," refers to a type of polymer that exhibits rubber-like
qualities. When polishing, the elastomer serves as a good buffer to
avoid scraping the surface of the substrate to be polished. In one
preferred embodiment of the invention, the elastomers are foam
resins. As used herein, the term "foam resin" refers to a material
containing a thermoplastic resin and a thermodecomposing foaming
agent. Preferably, the elastomers are at least one selected from
the group consisting of polyurethane, polyamide, polycarbonate,
polyaminonitrile, polymethacrylate, epoxyl resin, phenolic resins,
polymethyl methacrylate, polyaminoester, vinylbenzene polymer,
acrylic resin, and polyurethane.
[0032] The polishing pad according to the invention can avoid the
defects of the conventional polishing pad made of short fibers.
Because the bundle of first long fibers are able to form the base
mateiral without a cording process or a needle-punching process,
the uneven distribution of the fibers, aggregations of fibers and a
breakage of the fibers due to the processes are then avoided. As a
result, the elastomer according to the invention is evenly embedded
into the fibers. Furthermore, the cell size made of the fibers and
the elastomer, hardness, uniformity, density of the elastomer,
thickness, compression ratio, and recover rate after compression
are all improved. The slurry can flow smoothly and polishing
particles can diffuse evenly as well. The polishing pad according
to the invention does not damage the surface of the substrate to be
polished and balling is diminished dramatically. Furthermore, the
polishing efficiency is satisfied when the polishing pad according
to the invention is applied.
[0033] The present invention also provides a polishing system
comprising: [0034] a polishing pad as mentioned above; [0035] a
substrate to be polished; [0036] a slurry, wherein the slurry
together with the polishing pad react chemically with the surface
of the substrate to be polished; [0037] wherein the first long
fibers and the elastomer have the functions of carrying the slurry
and removing the reacted surface of the substrate to be polished in
a polishing process.
[0038] The present invention also provides a method of polishing a
substrate. The method comprises a step of using the polishing pad
as mentioned above to polish a surface of the substrate.
[0039] The present invention further provides a method of producing
the polishing pad as mentioned above. The method comprises steps
of: (a) providing a base material having a surface for polishing a
substrate, wherein the surface comprises a plurality of bundles of
first long fibers, and the bundles of first long fibers are
entangled with each other; (b) impregnating the surface of the base
material with an elastomer solution; and (c) curing the elastomer
impregnated in the surface of the base material.
[0040] In step (b) of the method, the manner of impregnating the
base material with an elastomer solution is the method of dipping
the fibers with the elastomer solution. The conditions for
impregnation are well known to artisans skilled in this field.
Suitable solvents used in the elastomer solution include
dimethylformamide (DMF). The elastomer solution optionally
comprises additives such as a detergent. Preferably, the elastomer
has a concentration ranging from 2 wt % to 60 wt % in the elastomer
solution.
[0041] Preferably, step (b) further comprises impregnating the
entire base material with the elastomer solution.
[0042] In step (c) of the method, the manner of curing the
elastomer impregnated in the base material is to cure the elastomer
in the base material. In one embodiment of the invention, the base
material is put into a curing solution for curing. Preferably, the
curing solution comprises 0 to 40 wt % dimethylformamide in water.
The conditions for curing are well known to artisans skilled in
this field. Preferably, the curing is carried out at room
temperature and pressure.
[0043] In one preferred embodiment of the invention, the method of
producing a polishing pad further comprises a step (c1) of washing
the base material after step (c). The purpose of washing is to
remove residues from the polishing pad. In one embodiment of the
invention, water is used in washing and extrusion wheels are
optionally used. The conditions for washing are well known to
artisans skilled in this field. Preferably, the base material is
washed in water at 50 to 90.degree. C. and then subjected to the
extrusion wheels several times.
[0044] In one more preferred embodiment of the invention, the
method of producing a polishing pad further comprises a step (c2)
of drying the base material after step (c1). The purpose of drying
is to remove the excess solvent from step (c1). The conditions for
drying are well known to artisans skilled in this field. In one
embodiment of the invention, the drying is air-drying, and the
drying temperature is in the range of 100.degree. C. to 160.degree.
C.
[0045] Preferably, the method of producing a polishing pad further
comprises a step (c3) of mechanically polishing the surface of the
base material and the elastomer. For example, the mechanical
polishing can be accomplished using a sand blast. The conditions
for mechanical polishing are well known to artisans skilled in this
field. More preferably, the fibers are exposed to the surface of
the base material after mechanical polishing.
[0046] In one preferred embodiment of the invention, steps (b) and
(c) are repeated several times. The kind of the elastomer used in
each time can be different or the same.
[0047] The following Examples are given for the purpose of
illustration only and are not intended to limit the scope of the
present invention.
EXAMPLE
[0048] Base Material: A polyethylene terephthalate chip was melt
spun at 260.degree. C. to 300.degree. C. and quenched at room
temperature. The chip was then subjected to a calender machine to
obtain a base material with 10 to 150 meshes and having a thickness
of 0.7 mm and a weight of 150 g/m.sup.2.
[0049] Fiber mat: A fabric was slivered for to obtain a mat.
Several sheets of the net were laid up and then woven with 70
Deniers of Nylon 6 yarn to obtain a 30-mesh sheet having a
thickness of 0.15 mm and a weight of 35 g/m.sup.2. The sheet was
then needle punched (700 times/m.sup.2) to obtain a fiber mat with
a weight of 475 g/m.sup.2.
[0050] Impregnating: The base material was impregnated in an
elastomer solution with a viscosity of 700 to 850 Cps. The
elastomer solution comprises 50 wt % of polyurethane, 49 wt % of
dimethylformamide and 1 wt % of detergent.
[0051] Curing: The base material, after impregnating, was put into
a curing solution comprising 25 wt % dimethylformamide in water to
mold the elastomer impregnated in the fibers.
[0052] Washing: The residues and the excess curing solution were
removed by extrusion wheels. The base material was then washed in
water at 80.degree. C. and then subjected to the extrusion wheels
several times.
[0053] Drying: The base material, after washing, was then dried at
140.degree. C.
[0054] Polishing: After drying, the base material was subjected to
mechanical polishing with #150 and #400 sand paper at 1200 and 1300
rpm, and a 1.28 mm product with a flat surface was obtained.
[0055] Assay: The polishing pad with a long fiber according to the
invention (long fiber) and a conventional polishing pad with a
short fiber (short fiber) was assayed and the results are shown in
Table 1. The compression ratio and recover rate after compression
of the polishing pad according to the invention are both improved
compared with the conventional polishing pad.
TABLE-US-00001 TABLE 1 Recover rate after Thickness (mm)
Compression ratio (%) compression (%) Long fiber 1.40 19.63 92.34
Short fiber 1.35 15.99 89.67
[0056] While embodiments of the present invention have been
illustrated and described, various modifications and improvements
can be made by persons skilled in the art. The embodiments of the
present invention are therefore described in an illustrative but
not restrictive sense. It is intended that the present invention is
not limited to the particular forms as illustrated, and that all
the modifications not departing from the spirit and scope of the
present invention are within the scope as defined in the appended
claims.
* * * * *