U.S. patent application number 11/369139 was filed with the patent office on 2006-11-30 for ultra fine fiber polishing pad and method for manufacturing 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, I-Peng Yao.
Application Number | 20060270329 11/369139 |
Document ID | / |
Family ID | 37464077 |
Filed Date | 2006-11-30 |
United States Patent
Application |
20060270329 |
Kind Code |
A1 |
Feng; Chung-Chih ; et
al. |
November 30, 2006 |
Ultra fine fiber polishing pad and method for manufacturing the
same
Abstract
A method is provided for making a polishing pad. In the method,
ultrafine fiber-generating fibers are made into a non-woven fabric
with two sides. At least one of the sides of the non-woven fabric
is made a dense layer. The non-woven fabric is coated with a
polymer. Because of the dense layer, the polymer cannot penetrate
the non-woven fabric. The ultrafine fiber-generating fibers are
converted to ultrafine fibers. Since the dense layer prevents the
polymer from penetrating the ultrafine fiber-generating fibers, the
ultrafine fibers remain a high concentration of fiber. The
ultrafine fibers are transformed into nap. Therefore, the polishing
pad is made with a polishing layer that includes the nap. The
concentration of fiber of the polishing layer is higher than
80%.
Inventors: |
Feng; Chung-Chih; (Sanmin,
TW) ; Chao; Chen-Hsiang; (Zuoying, TW) ; Yao;
I-Peng; (Sanmin, TW) |
Correspondence
Address: |
NIKOLAI & MERSEREAU, P.A.
900 SECOND AVENUE SOUTH
SUITE 820
MINNEAPOLIS
MN
55402
US
|
Assignee: |
SAN FANG CHEMICAL INDUSTRY CO.,
LTD.
Jenwu Shiang
TW
|
Family ID: |
37464077 |
Appl. No.: |
11/369139 |
Filed: |
March 6, 2006 |
Current U.S.
Class: |
451/536 |
Current CPC
Class: |
B24B 37/24 20130101;
Y10T 428/24612 20150115; B24D 11/003 20130101 |
Class at
Publication: |
451/536 |
International
Class: |
B24D 11/00 20060101
B24D011/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 27, 2005 |
TW |
094117355 |
Claims
1. A polishing pad comprising ultrafine fibers and a polymer that
binds the ultrafine fibers, the polishing pad comprising a
polishing layer that is made dense in order to include a
concentration of fiber higher that of the remaining portion of the
polishing pad.
2. The polishing pad according to claim 1 wherein the concentration
of fiber of the polishing layer is higher than 80%.
3. The polishing pad according to claim 1 wherein the fineness of
the ultrafine fibers is lower than 0.05 dtex.
4. A method for making a polishing pad, the method comprising the
following steps of: making ultrafine fiber-generating fibers into a
non-woven fabric with two sides; making at least one of the sides
into a dense layer; coating the non-woven fabric with a polymer
that forms a coating; converting the ultrafine fiber-generating
fibers to ultrafine fibers; and processing the coating on the dense
layer so that the fineness of the ultrafine fibers on the dense
layer is lower than 0.05 dtex.
5. The method according to claim 4 wherein the step of making the
dense layer includes the step of heating the side of the non-woven
fabric at a temperature higher than 100 degrees Celsius.
6. The method according to claim 5 wherein the step of making the
dense layer includes the step of pressing the side of the non-woven
fabric while heating the side of the non-woven fabric.
7. The method according to claim 4 wherein the step of processing
the coating comprises the step of grinding the coating.
8. A method for making a polishing pad, the method comprising the
following steps of: making ultrafine fiber-generating fibers into a
non-woven fabric with two sides; coating at least one of the sides
with a dissolvable substance; coating the non-woven fabric with a
polymer that forms a coating; washing away the dissolvable
substance; converting the ultrafine fiber-generating fibers to
ultrafine fibers; and processing the coating on the dense layer so
that the fineness of the ultrafine fibers on the dense layer is
lower than 0.05 dtex.
9. The method according to claim 8 wherein the dissolvable
substance is selected from a group consisting of polyvinyl alcohol,
methyl cellulose, sodium bicarbonate and amylase.
10. The method according to claim 8 wherein the step of processing
the coating comprises the step of grinding the coating.
11. The method according to claim 8 wherein the sequence of the
step of washing away the dissolvable substance and the step of
converting the ultrafine fiber-generating fibers to ultrafine
fibers is changeable.
Description
BACKGROUND OF INVENTION
[0001] 1. Field of Invention
[0002] The present invention relates to a polishing pad for
polishing the surfaces of objects such as semiconductors, storage
medium substrates, integrated circuits and electro-optical panels,
and relates to a method for making the polishing pad.
[0003] 2. Related Prior Art
[0004] In the semiconductor industry, there is a trend toward the
reduction of the semiconductor characteristics and the increasing
of the superficial planarity. In detail, it is preferred to provide
a surface with an even form by reducing the quantity and size of
superficial flaws.
[0005] Polishing is often used to turn a rough surface into a
smooth surface. Amid other polishing methods, there are fixed-type
polishing methods and suspension-type polishing methods.
[0006] In a fixed-type polishing method, used is a fixed-type
polishing pad with a polishing layer on a substrate. The substrate
is a PET foil for example. The polishing layer includes polishing
particles and an adhesive for fixing the polishing particles to the
substrate. Although providing a high polishing rate, the fixed-type
polishing pad causes grave impacts on the polished surface, and it
is difficult to clean the polished surface of debris. Hence, many
large and deep scratches are made in the polished surface, and this
is not desirable.
[0007] In a suspension-type polishing method, used is a
suspension-type polishing pad with a polishing solution on a
substrate. The polishing solution is a suspension with polishing
particles suspended in a solvent. For the use of the solvent, it is
easy to clean the polished surface of debris. As suspended in the
solvent, the polishing particles freely move. Hence, the impacts on
the polished surface by the suspended polishing particles can
readily be adjusted. Moreover, it is easy to control the result by
changing the suspension-type polishing pad. Various velvets and
fabrics are used in the suspension-type polishing pad to achieve
adequate effects according to different purposes.
[0008] In the suspension-type polishing method, the polishing
solution is provided between the substrate and the polished
surface, and the substrate is regularly rotated related to the
polished surface. The substrate of the suspension-type polishing
pad may include urethane or polyurethane plastics filled in a
blanket made of polyester. Alternatively, the blanket may be made
of natural fibers such as wool for instance.
[0009] Chemical mechanical polishing ("CMP") is often used in a
typical machine for polishing semiconductor devices. In a CMP
method, a polishing pad includes a polishing solution on a
substrate. The polishing pad is used to polish the surfaces of
semiconductor devices. The polishing solution is provided between a
wafer and the substrate, and the wafer is pressed on and rotated
relative to the polishing pad while chemical substances in the
polishing solution and the pressure and rate between the wafer and
the polishing pad and temperature are under control. The polishing
solution includes polishing particles capable of mechanically
polishing the surface of the wafer when mixed with the chemical
substances. Between the chemical substances and the surface of the
wafer, chemical reactions such as removal and oxidation happen. The
polishing pad often includes a continuous substrate. When the wafer
is rotated relative to the polishing pad, some redundant material
is mechanically removed from the surface of the wafer by the
polishing particles of the polishing liquid while some other
redundant material is chemically removed from the surface of the
wafer by the solvent of the polishing liquid.
[0010] Disclose in US Patent Application Publication 2002/0013984A1
is a sheet for texturing and a method of producing the same. The
method includes four steps among which the second and third steps
can be interchanged.
[0011] Firstly, a non-woven fabric is composed of ultrafine
fiber-generating fibers (a) and (b).
[0012] Secondly, an elastomer is filled in the non-woven fabric so
as to form a sheet.
[0013] Thirdly, the ultrafine fiber-generating fibers (a) are
converted to bundles of ultrafine fibers while the ultrafine
fiber-generating fibers (b) are converted to bundles of ultrafine
fibers not more than 0.03 dtex in fineness.
[0014] Fourthly, at least one side of the sheet is grinded so that
the ultrafine fibers under 0.03 dtex in fineness form nap.
[0015] A polishing layer is formed on the side of the sheet on
which the nap is formed. However, in the step of converting the
fibers (a) and (b) to the ultrafine fibers, since the polishing
layer includes the polymer and the fibers, the polishing layer
cannot adequately be opened so that the nap is not fine enough and
that the nap may get entangled. If the polishing layer contains too
much polymer, when it is used to polish an object, particles
(polishing synthetic materials, sheet materials, polishing
particles, particles of sheet materials and debris of the object)
will stick to the polymer of the polishing layer and cannot
smoothly be removed by a polishing solution. These redundant
particles will wear away the object and jeopardize the polishing of
the object.
[0016] The present invention is therefore intended to obviate or at
least alleviate the problems encountered in prior art.
SUMMARY OF INVENTION
[0017] It is the primary objective of the present invention to
provide a polishing pad with ultrafine fibers that are highly
opened and therefore do not cause damages to an object.
[0018] According to the present invention, a method is provided for
making a polishing pad. In the method, ultrafine fiber-generating
fibers are made into a non-woven fabric with two sides. At least
one of the sides of is made a dense layer. The dense layer may be
made by heating the side or coating the side with a dissolvable
substance. The non-woven fabric is coated with a polymer. Because
of the dense layer, the polymer cannot penetrate the non-woven
fabric. The ultrafine fiber-generating fibers are converted to
ultrafine fibers. Since the dense layer prevents the polymer from
penetrating the ultrafine fiber-generating fibers, the ultrafine
fibers includes a high concentration of fiber. The ultrafine fibers
are transformed into nap. A polishing pad is completed.
[0019] In use, the nap of a polishing layer of the polishing pad
will not get entangled and cause damages to an object polished by
the polishing pad.
[0020] The dense layer can be made by heating the surface of the
non-woven fabric higher than 100 degrees Celsius so that the
surfaces of the ultrafine fiber-generating fibers are transformed
and made dense.
[0021] Alternatively, the dense layer can be made by coating the
non-woven fabric with a dissolvable substance such as polyvinyl
alcohol, methyl cellulose, sodium bicarbonate and amylase. The
dissolvable substance can be washed away with water.
[0022] In an aspect of the present invention, a method is provided
making a polishing pad. The method includes the step of making
ultrafine fiber-generating fibers into a non-woven fabric with two
sides, the step of making at least one of the sides a dense layer,
the step of coating the non-woven fabric with a polymer that forms
a coating, the step of converting the ultrafine fiber-generating
fibers to ultrafine fibers and the step of processing the coating
on the dense layer so that the fineness of the ultrafine fibers on
the dense layer is lower than 0.05 dtex.
[0023] In an aspect of the present invention, a method is provided
making a polishing pad. The method includes the step of making
ultrafine fiber-generating fibers into a non-woven fabric with two
sides, the step of coating at least one of the sides with a
dissolvable substance, the step of coating the non-woven fabric
with a polymer that forms a coating, the step of washing away the
dissolvable substance, the step of converting the ultrafine
fiber-generating fibers to ultrafine fibers and step of processing
the coating on the dense layer so that the fineness of the
ultrafine fibers on the dense layer is lower than 0.05 dtex.
[0024] The sequence of the step of washing away the dissolvable
substance and the step of converting the ultrafine fiber-generating
fibers to ultrafine fibers is changeable.
[0025] In still another aspect of the present invention, a
polishing pad includes ultrafine fibers and a polymer that binds
the ultrafine fibers. The polishing pad includes a polishing layer
that is made dense in order to include a concentration of fiber
higher that of the remaining portion of the polishing pad.
[0026] The polishing pad can be used to polish any substrate made
of glass, metal, metal oxide, metal alloy or semi-conductor or any
combination thereof.
[0027] The substrate may include any proper metal such as copper,
aluminum, tantalum, titanium, tungsten, gold, platinum, iridium,
ruthenium and any combination thereof such as alloy and
mixture.
[0028] The substrate may include any proper metal oxide such as
aluminum oxide, silicon oxide, titanium oxide, cerium oxide,
zirconium oxide, germanium oxide, magnesium oxide and any
combination thereof.
[0029] The substrate may include any proper metal alloy such as
metal nitride (such as tantalum nitride, titanium nitride and
tungsten nitride), metal carbide (such as silicone carbide and
tungsten carbide), nickel-phosphorous, aluminum-silicone-boron,
silicone-boron glass, silicone-phosphorous glass,
silicone-phosphorous-boron glass, silicone-germanium alloy,
silicone-germanium-carbon alloy.
[0030] The substrate may include any proper semi-conductor such as
mono-crystalline silicone, multi-crystalline silicone, amorphous
silicone, silicon-on-insulator and gallium arsenide.
[0031] Other objectives, advantages and features of the present
invention will become apparent from the following description
referring to the drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0032] A polishing pad according to the preferred embodiment of the
present invention will be described referring to the drawings.
[0033] FIG. 1 is a SEM view of a conventional polishing pad.
[0034] FIG. 2 is a SEM view of the polishing pad according to the
preferred embodiment of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0035] In a method according to a general concept of the present
invention, ultrafine fiber-generating fibers are made into a
non-woven fabric with two sides. At least one of the sides of the
non-woven fabric is made a dense layer. The non-woven fabric is
coated with a polymer such as a polyurethane resin, a
polyvinylchloride resin, a polystyrene resin, a polyvinyl resin, a
polyamide resin, a propylene resin and a vinyl-vinylacetate resin.
Because of the dense layer, the polymer cannot penetrate the
non-woven fabric.
[0036] The dense layer can be made by heating the side of the
non-woven fabric at a temperature higher than 100 degrees Celsius
so that the surfaces of the ultrafine fiber-generating fibers are
transformed and made dense. While being heated, the side of the
non-woven fabric can be pressed.
[0037] Alternatively, the dense layer can be made by coating the
non-woven fabric with a dissolvable substance such as polyvinyl
alcohol, methyl cellulose, sodium bicarbonate and amylase. The
concentration of the dissolvable substance is 5% to 15% and
provided with a roller at 100 to 200 g/m.sup.2. Thus, when the
polymer is coated on the non-woven fabric, the polymer cannot
penetrate the non-woven fabric since the dissolvable substance has
occupied the superficial space. The dissolvable substance can be
washed away with water.
[0038] The ultrafine fiber-generating fibers are converted to
ultrafine fibers. Since the dense layer prevents the polymer from
penetrating the ultrafine fiber-generating fibers, the ultrafine
fibers includes a high concentration of fiber. The ultrafine fibers
are transformed into nap. A polishing pad is completed. In use, the
nap of a polishing layer of the polishing pad will not get
entangled and cause damages to an object polished by the polishing
pad.
[0039] According to a first embodiment of the present invention,
ultrafine fiber-generating fibers are made into a non-woven fabric.
The side of the non-woven fabric is heated at 120 degrees Celsius
and hence made dense. The non-woven fabric is coated with a
polyurethane resin that forms a coating. At least one of the sides
of the non-woven fabric is grinded so that a polishing pad is
formed with a polishing layer that includes nap less than 0.05
dtex. The dense layer remains a high concentration of fiber.
[0040] According to a second embodiment of the present invention,
ultrafine fiber-generating fibers are made into a non-woven fabric.
A gravure roll is used to coat the non-woven fabric with a 5% to
15% dissolvable solution of methyl cellulose at 100 to 200
g/m.sup.2. The side of the non-woven fabric is made dense in order
to prevent polymers from penetrating the non-woven fabric. The
non-woven fabric is coated with a polyurethane resin that forms a
coating. The non-woven fabric is washed in order to remove the
methyl cellulose. At least one of the sides of the non-woven fabric
is grinded so that a polishing pad is formed with a polishing layer
that includes nap less than 0.05 dtex. The dense layer still
includes a high concentration of fiber.
[0041] Referring to FIG. 2, there is shown a polishing pad made in
a method according to the present invention. The nap on the
polishing layer is even and dense. The concentration of fiber of
the dense layer is higher than 80%. On the contrary, referring to
FIG. 1, the concentration of polyurethane of a polishing pad made
in a conventional method is 45% to 50%. The concentration of
polyurethane of the polishing pad of the present invention is 30%
less than that of the conventional polishing pad. The polishing pad
of the present invention is more flexible and hangs better than the
conventional polishing pad. The polishing pad of the present
invention makes fewer scratches than the conventional polishing
pad. The scratches made by the polishing pad of the present
invention are lower than 1000/.mu.m.sup.2. The scratches made by
the conventional polishing pad are 2000/.mu.m.sup.2 to
25000/.mu.m.sup.2.
[0042] It is noted that the ultrafine fiber-generating fibers may
be conjugate fibers or composite fibers.
[0043] The present invention has been described by the detailed
description of the embodiments. Those skilled in the art can derive
variations from the embodiments without departing from the scope of
the present invention. Therefore, the embodiments shall not limit
the scope of the present invention defined in the claims.
* * * * *