U.S. patent application number 10/503413 was filed with the patent office on 2005-07-14 for polishing pad, polishing apparatus, and polishing method.
Invention is credited to Shibuki, Shunichi.
Application Number | 20050153633 10/503413 |
Document ID | / |
Family ID | 27736451 |
Filed Date | 2005-07-14 |
United States Patent
Application |
20050153633 |
Kind Code |
A1 |
Shibuki, Shunichi |
July 14, 2005 |
POLISHING PAD, POLISHING APPARATUS, AND POLISHING METHOD
Abstract
A polishing pad which ensures that a work can be easily removed
from the polishing pad surface after polishing, the amount of a
polishing liquid used for polishing can be reduced, and the
production cost of the polishing pad can be lowered. A first
polishing pad (1) for polishing a work is provided with a plurality
of slots (11) piercing the first polishing pad (1) in a sa
direction, the length in the longitudinal direction of the slots
(11) being preferably not less than 20 mm, the pitch in the width
direction of the slots (11) being preferably less than 100 mm, and
small holes (not shown) may be provided in addition to the slots
(11).
Inventors: |
Shibuki, Shunichi;
(Kanagawa, JP) |
Correspondence
Address: |
ROBERT J. DEPKE LEWIS T. STEADMAN
TREXLER, BUSHNELL, GLANGLORGI, BLACKSTONE & MARR,
105 WEST ADAMS STREET
SUITE 3600
CHICAGO
IL
60603-6299
US
|
Family ID: |
27736451 |
Appl. No.: |
10/503413 |
Filed: |
March 7, 2005 |
PCT Filed: |
February 7, 2003 |
PCT NO: |
PCT/JP03/01305 |
Current U.S.
Class: |
451/41 ;
451/527 |
Current CPC
Class: |
B24B 37/26 20130101 |
Class at
Publication: |
451/041 ;
451/527 |
International
Class: |
B24B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 7, 2002 |
JP |
2002-30322 |
Nov 12, 2002 |
JP |
2002-327853 |
Claims
1. A polishing pad for polishing a work, which is provided with a
plurality of slots piercing through said polishing pad in the
thickness direction.
2. A polishing pad as set forth in claim 1, wherein said slots are
so formed as to be included in said polishing pad, and the length
in the longitudinal direction of said slots is not less than 20
mm.
3. A polishing pad as set forth in claim 1, wherein the pitch in
the transverse direction of said slots is not less than twice the
length in the transverse direction of said slots and is less than
100 mm.
4. A polishing pad for polishing a work, which is provided with a
plurality of holes piercing through said polishing pad in the
thickness direction, part of said plurality of holes being composed
of slots.
5. A polishing pad as set forth in claim 4, wherein said slots are
so formed as to be included in said polishing pad, and the length
in the longitudinal direction of said slots is not less than 20
mm.
6. A polishing pad as set forth in claim 4, wherein the pitch in
the transverse direction of said slots is not less than twice the
length in the transverse direction of said slots and less than 100
mm.
7. A polishing apparatus for polishing a surface to be polished of
a material to be polished, by bringing a polishing pad into contact
with said surface and into a frictional motion relative to said
surface, wherein said polishing pad is provided with a plurality of
slots piercing through said polishing pad in the thickness
direction.
8. A polishing apparatus as set forth in claim 7, wherein said
slots are so formed as to be included in said polishing pad, and
the length in the longitudinal direction of said slots is not less
than 20 mm.
9. A polishing apparatus as set forth in claim 7, wherein the pitch
in the transverse direction of said slots is not less than twice
the length in the transverse direction of said slots and is less
than 100 mm.
10. A polishing apparatus for polishing a surface to be polished of
a material to be polished, by bringing a polishing pad into contact
with said surface, and into a frictional motion relative to said
surface, wherein said polishing pad is provided with a plurality of
holes piercing through said polishing pad in the thickness
direction, part of said plurality of holes being composed of
slots.
11. A polishing apparatus as set forth in claim 10, wherein said
slots are so formed as to be included in said polishing pad, and
the length in the longitudinal direction of said slots is not less
than 20 mm.
12. A polishing apparatus as set forth in claim 10, wherein the
pitch in the transverse direction of said slots is not less than
twice the length in the transverse direction of said slots and is
less than 100 mm.
13. A polishing method for polishing a surface to be polished of a
material to be polished, by bringing a polishing pad into contact
with said surface, and bringing said surface and said polishing pad
into a frictional motion relative to each other, wherein said
polishing pad is provided with a plurality of slots piercing
through said polishing pad in the thickness direction.
14. A polishing method as set forth in claim 13, wherein said slots
are so formed as to be included in said polishing pad, and the
length in the longitudinal direction of said slots is not less than
20 mm.
15. A polishing method as set forth in claim 13, wherein the pitch
in the transverse direction of said slots is not less than twice
the length in the transverse direction of said slots and is less
than 100 mm.
16. A polishing method for polishing a surface to be polished of a
material to be polished, by bringing a polishing pad into contact
with said surface, and bringing said surface and said polishing pad
into a frictional motion relative to each other, wherein said
polishing pad is provided with a plurality of holes piercing
through said polishing pad in the thickness direction, part of said
plurality of holes being composed of slots.
17. A polishing method as set forth in claim 16, wherein said slots
are so formed as to be included in said polishing pad, and the
length in the longitudinal direction of said slots is not less than
20 mm.
18. A polishing method as set forth in claim 16, wherein the pitch
in the transverse direction of said slots is not less than twice
the length in the transverse direction of said slots and is less
than 100 mm.
Description
TECHNICAL FIELD
[0001] The present invention relates to a polishing pad, a
polishing apparatus and a polishing method, and particularly to a
polishing pad provided with a plurality of slots, a polishing
apparatus using the polishing pad, and a polishing method using the
polishing pad.
BACKGROUND ART
[0002] As Related Art 1, there have been commercialized polishing
pads which are provided grooves in the surface thereof. For
example, there is available the polishing pad IC1000-A22 produced
by Rodel Nitta Company. As shown in FIG. 9, this polishing pad 61
is provided in its polishing pad surface 61S with grooves 62, 2 mm
in width, in a lattice pattern at a pitch of about 2 cm.
Incidentally, the grooves 62 are omitted in the plan view.
[0003] As Related Art 2, there have been commercialized polishing
pads provided with a plurality of small holes (for example, small
holes of 1.8 mm in diameter) in the surface thereof. One example
known of this type of polishing pads is the polishing pad IC1000
(p) produced by Rodel Nitta Company.
[0004] As Related Art 3, there has been disclosed, as shown in FIG.
10, a polishing pad 71 which is provided with a plurality of holes
72 and with a plurality of grooves 73 in its surface 71S.
Incidentally, the holes 72 and the grooves 73 are omitted in the
plan view. No description is given about the diameter of the holes
in Japanese Patent No. 3042593. Generally, however, the polishing
pads provided with holes of 1.8 mm in diameter in a density of
about 3 to 5 pieces/cm.sup.2 are often used. Incidentally, it is
described in Japanese Patent No. 3042593 that the width of the
grooves may be not more than the diameter of the holes, that the
depth of the grooves may be about 0.3 mm, and that the groove depth
may be up to 0.5 mm (see, for example, Patent Document 1).
[0005] In the polishing pad according to Related Art 3, provision
of the holes restrains the polishing resistance from increasing. In
addition, with the grooves formed in the polishing pad surface, the
hermetic seal property between the polishing pad surface and a
semiconductor wafer is lowered, so that a negative pressure is less
liable to be generated there. Therefore, it is easy to remove the
semiconductor wafer from the polishing pad surface after completion
of the polishing. Besides, the polishing pad according to Related
Art 3 has the characteristic features that the strength of the hard
layer is restrained from being lowered, the load on the soft layer
is reduced, and deterioration thereof with time is suppressed, as
compared to the polishing pads provided with ordinary grooves.
[0006] In addition, chemical mechanical polishing (hereinafter
referred to as CMP) has been used, for example, at the time of
planarizing the surface of an insulation film in the manufacturing
process of a semiconductor device, and at the time of removing
surplus materials in the formation of copper wirings, tungsten
plugs or the like.
[0007] A CMP apparatus which has been widely used has a structure
in which the polishing surface of the polishing pad is planar, the
surface to be polished of a wafer and the polishing surface of the
polishing pad are disposed parallel to each other, and they make
contact while being rotated respectively, whereby polishing is
performed (see, for example, Patent Document 2).
[0008] Furthermore, there have been known a belt-type CMP apparatus
(see, for example, Patent Document 3), (see, for example Patent
Document 4), a rectilinear oscillation type CMP apparatus (see, for
example, Patent Document 5), a CMP apparatus comprising a
ring-shaped polishing pad (see, for example, Patent Document 6),
and a roller-type CMP apparatus (see, for example, Patent Document
7). In every one of the above-mentioned polishing apparatuses, the
polishing surface of the polishing pad brought into contact with
the surface to be polished is planar.
[0009] Patent Document 1: Japanese Patent Laid-open No. Hei
9-117855 (p. 4, FIG. 1, FIG. 5)
[0010] Patent Document 2: Japanese Patent Laid-open No. 2000-218514
(p. 4, FIG. 5)
[0011] Patent Document 3: Japanese Patent Laid-open No. 2000-218514
(p. 4, FIG. 6)
[0012] Patent Document 4: Japanese Patent Laid-open No. Hei 8-52652
(pp. 5-6, FIG. 1)
[0013] Patent Document 5:. Japanese Patent Laid-open No. Hei
8-52652 (p. 8, FIG. 10)
[0014] Patent Document 6: Japanese Patent Laid-open No. Hei
11-31671 (p. 5, FIG. 1)
[0015] Patent Document 7: Japanese Patent Laid-open No. Hei
2-139172 (pp. 3-5, FIGS. 1 to 3)
[0016] However, the polishing pad according to the above-mentioned
Related Art 1 has the problem that the polishing liquid would flow
out through the grooves during polishing, and a large amount of the
polishing liquid is needed. Besides, since the grooves are formed
by cutting, the production cost of the polishing pad is higher, as
compared with polishing pads which are provided with holes by
punching.
[0017] The polishing pad according to the Related Art 2 has the
disadvantage that the polishing resistance is raised because a
negative pressure is generated between the polishing pad and the
work in the areas of the holes. Furthermore, it is difficult to
remove the work from the polishing pad after completion of the
polishing. A detailed description of this phenomenon is given also
in Japanese Patent Laid-open No. Hei 9-117855.
[0018] The polishing pad according to the Related Art 3 has the
drawback that the production cost thereof is high, since the
grooves must be formed by cutting after the formation of the holes
by punching.
[0019] The problems involved in the polishing pads as
above-mentioned cannot be solved by the polishing apparatuses and
polishing methods using the polishing pads described in the
above-mentioned Related Arts.
DISCLOSURE OF INVENTION
[0020] The present invention pertains to a polishing pad, a
polishing apparatus, and a polishing method invented for solving
the above-mentioned problems.
[0021] The first polishing pad according to the present invention
is a polishing pad for polishing a work, which is provided with a
plurality of slots piercing through the polishing pad in the
thickness direction.
[0022] In the first polishing pad, since the plurality of slots
piercing through the polishing pad in the thickness direction are
provided, the hermetic seal property between the surface to be
polished and the polishing pad surface is lowered, so that a
negative pressure is less liable to be generated there.
Accordingly, it is easy to remove the work from the polishing pad
surface after completion of polishing. In addition, since the slots
formed in the polishing pad according to the present invention can
be formed by punching, the polishing pad is lower in production
cost than a polishing pad provided with grooves formed by
cutting.
[0023] The second polishing pad according to the present invention
is a polishing pad for polishing a work, which is provided with a
plurality of holes piercing through the polishing pad in the
thickness direction, part of the plurality of holes being composed
of slots.
[0024] In the second polishing pad, since the plurality of holes
piercing through the polishing pad in the thickness direction are
provided and part of the plurality of holes are composed of clots,
the hermetic seal property of between the surface to be polished
and the polishing pad surface is lowered due to the presence of the
slots and a negative pressure is less liable to be generated there,
in the same manner as in the case of the first polishing pad.
Therefore, it is easy to remove the work from the polishing pad
surface after completion of polishing. Further, since a plurality
of holes other than the slots are provided, the polishing
resistance is restrained from increasing. Furthermore, since
grooves are not provided in the present polishing pad, unlike the
related-art polishing pads, there is no possibility that a
polishing liquid might flow out through grooves to the exterior of
the polishing pad. The slots formed in the polishing pad according
to the present invention reserve the polishing liquid therein,
which makes it possible to reduce the amount of the polishing
liquid used. In addition, since the plurality of holes inclusive of
the slots which are formed in the polishing pad according to the
present invention can be formed by a single punching operation, the
polishing pad is lower in production cost than the polishing pads
provided with grooves which are formed by cutting. Further, since
the slots are so formed as to pierce through the polishing pad in
the thickness direction, the slots are not lost even when the
polishing pad is worn as polishing proceeds. Accordingly, the
polishing pad according to the present invention can show a longer
pad life, as compared with the polishing pads provided with
grooves.
[0025] A polishing apparatus according to the present invention is
a polishing apparatus which uses a polishing pad according to the
present invention, whereby the production cost of the polishing pad
can be lowered. Since a polishing pad according to the present
invention is thus used, the operating cost of the polishing
apparatus is lowered. Furthermore, since the polishing pad
according to the present invention has a longer pad life than that
of a related-art polishing pad provided with grooves, the frequency
of replacement of the polishing pad is reduced.
[0026] A polishing method according to the present invention is a
polishing method in which a polishing pad according to the present
invention is used, whereby the production cost of the polishing pad
can be lowered. Since a polishing pad according to the present
invention is thus used, polishing cost is lowered. Furthermore,
since the polishing pad according to the present invention has a
longer pad life than that of a related-art polishing pad provided
with grooves, the frequency of replacement of the polishing pad is
reduced.
BRIEF DESCRIPTION OF DRAWINGS
[0027] FIG. 1 shows a plan view and a partly enlarged view
illustrating a first embodiment of the first polishing pad
according to the present invention.
[0028] FIG. 2 shows a plan view and a partly enlarged view
illustrating a first embodiment of the second polishing pad
according to the present invention.
[0029] FIG. 3 is a plan view showing an embodiment of slots formed
in the first and second polishing pads according to the present
invention.
[0030] FIG. 4 is a plan view showing another embodiment of slots
formed in the first and second polishing pads according to the
present invention.
[0031] FIG. 5 is a plan view illustrating a second embodiment of
the first polishing pad according to the present invention.
[0032] FIG. 6 shows a plan view illustrating a second embodiment of
the second polishing pad according to the present invention.
[0033] FIG. 7 is a schematic configurational perspective view
illustrating an embodiment of the first polishing apparatus
according to the present invention.
[0034] FIG. 8 is a schematic configurational perspective view
illustrating an embodiment of the second polishing apparatus
according to the present invention.
[0035] FIG. 9 shows a plan view, a partly enlarged view and a
sectional view along line A-A' illustrating a polishing pad
according to Related Art 1.
[0036] FIG. 10 shows a plan view, a partly enlarged view and a
sectional view along line B-B' illustrating a polishing pad
according to Related Art 3.
BEST MODE FOR CARRYING OUT THE INVENTION
[0037] A first embodiment of the first polishing pad according to
the present invention will be described referring the plan view and
the partly enlarged view shown in FIG. 1.
[0038] As shown in FIG. 1, the first polishing pad 1 is provided
with a plurality of slots 11 piercing through the polishing pad 1
in the thickness direction, the slots 11 being aligned in the row
direction and the column direction. The polishing pad 1 is formed
of a resin, for example, foamed polyurethane or urethane. Its
thickness is comparable to those of ordinary polishing pads, and
is, for example, about 0.5 to 3.0 mm. The slots 11 are so formed as
to be included in the polishing pad 1, and their length L in the
longitudinal direction is not less than 20 mm. In addition, the
slots 11 are formed at a pitch p which is not less than twice the
length in the transverse direction (hereinafter referred to as the
width) W thereof and is less than 100 mm. Incidentally, the spacing
d in the longitudinal direction of the slots 11 is appropriately
set; here, as an example, the spacing d is 10 mm. Besides, the
slots 11 may be formed to be staggered from each other in either
one or both of the row direction and the column direction.
[0039] Since the first polishing pad is provided with the plurality
of slots 11 piercing through the first polishing pad 1 in the
thickness direction, the hermetic seal property between the surface
to be polished and the surface of the polishing pad 1 is lowered
and a negative pressure is less liable to be generated there, so
that it is easy to remove the work from the surface of the
polishing pad 1 after completion of polishing. In addition, the
slots 11 formed in the first polishing pad 1 according to the
present invention can be formed by punching, the polishing pad 1 is
lower in production cost than a polishing pad provided with grooves
by cutting. Further, since the slots 11 are so formed as to piece
through the first polishing pad 1 in the thickness direction, the
slots 11 are not lost even when the first polishing pad 1 is worn.
Therefore, the first polishing pad 1 can show a prolonged pad life,
as compared with the related-art polishing pads provided with
grooves.
[0040] Next, a first embodiment of the second polishing pad
according to the present invention will be described referring to
the plan view and the partly enlarged view shown in FIG. 2.
Incidentally, small holes are omitted in the plan view.
[0041] As shown in FIG. 2, the second polishing pad 2, like the
first polishing pad 1, is provided with slots 11 piercing through
the second polishing pad 2 in the thickness direction in the state
of being aligned, for example, in the row direction and the column
direction, and is provided with a plurality of holes (hereinafter
referred to as small holes) 21 piercing through the second
polishing pad 2 in the thickness direction and having a diameter D
of 10 mm or below, preferably, 5 mm or below. Specifically, the
slots 11 are included in the polishing pad 1, and have a length L
of not less than 20 mm. In addition, the slots 11 are formed at a
pitch p1 of not less than twice the width W thereof and less than
100 mm. Incidentally, the spacing d in the longitudinal direction
of the slots 11 is appropriately set; here, as an example, the
pitch p1 is 10 mm. In addition, the slots 11 may be formed to be
staggered from each other in either one or both of the row
direction and the column direction.
[0042] Further, the small holes 21 are composed of holes having a
diameter D=1.8 mm, for example, and are uniformly arranged in a
lattice point pattern at pitches p2x=p2y=5 mm. Incidentally, the
small holes 21 are preferably so formed as not to overlap with the
slots 11. Besides, the arrangement of the small holes 21 is not
limited to the lattice point pattern, inasmuch as the small holes
21 are formed at predetermined pitches over the entire surface area
of the polishing pad.
[0043] In the second polishing pad 2, since there are provided the
pluralities of slots 11 and small holes 21 piercing through the
second polishing pad 2 in the thickness direction, the hermetic
seal property between the surface to be polished and the surface of
the second polishing pad 2 is lowered due to the presence of the
slots 11, so that a negative pressure is less liable to be
generated there, like in the case of the first polishing pad 1.
Therefore, it is easy to remove the work from the surface of the
second polishing pad 2 after completion of polishing. In addition,
since the slots 11 reserve the polishing liquid therein, it is
possible to reduce the amount of the polishing liquid used.
[0044] Further, since the plurality of small holes 21 other than
the slots 11 are provided, the polishing resistance can be
prevented from increasing. Furthermore, since grooves are not
provided, unlike the related-art polishing pads, there is no
possibility that the polishing liquid might flow out through
grooves to the exterior of the polishing pad.
[0045] In addition, since the slots 11 and the small holes 21
formed in the second polishing pad 2 according to the present
invention can be formed by a single punching operation, the
production cost is lower than that of a polishing pad provided with
grooves by cutting.
[0046] Further, since the slots 11 and the small holes 21 are so
formed as to pierce through the second polishing pad 2 in the
thickness direction, the slots 11 and the small holes 21 are not
lost even when the second polishing pad 2 is worn as polishing
proceeds. As a result, the second polishing pad 2 can show a
prolonged pad life, as compared with polishing pads provided with
grooves.
[0047] Next, the possibility of generation of troubles during
conveying of polishing pads was investigated by using the first and
second polishing pads 1 and 2 and varying the length of the slots,
the width of the slots, and the pitch in the width direction of the
slots. The spacing d in the longitudinal direction of the slots 11
shown in FIGS. 1 and 2 was fixed at 10 mm. In each polishing, a
silicon wafer provided on its surface with a solid film of silicon
oxide was used as a work, the silicon oxide film as a surface to be
polished was polished once, and it was checked 10 times if the
silicon wafer could conveyed. The results are summarized in Table 1
below.
1TABLE 1 IC1000/SUBA400 IC1000/SUBA400 laminate laminate
IC1000/SUBA400 IC1000/SUBA400 Without With small IC1000 IC1000
laminate laminate small holes holes Width Pitch monolayer monolayer
Without small With small holes Slots Both slots and Length of of
Without With holes Both slots and piercing small holes of slots
slots slots small small Slots in IC1000 small holes in through
piercing through (mm) (mm) (mm) holes holes only IC1000 only
IC1000/SUBA400 IC1000/SUBA400 10 2 40 0.3 0.8 0.4 1 0.4 1 20 0.5 10
0 0 0 0 0 0 1 20 0 0 0 0 0 0 2 100 0 0.2 0 0.3 0 0.4 40 0 0 0 0 0 0
25 0 0 0 0 0 0 20 0 0 0 0 0 0 10 0 0 0 0 0 0 30 2 40 0 0 0 0 0 0 40
2 0 0 0 0 0 0 50 2 0 0 0 0 0 0 Without slots 0.2 0.7 0.2 1 0.1
1
[0048] In the above investigation, a foamed polyurethane-made
polishing pad (for example, the IC1000 monolayer product, 1.2 mm
thick, produced by Rodel Inc.) and a laminated polishing pad
comprising a foamed polyurethane-made upper layer and a PET
(polyethylene terephthalate)-made lower layer (for example, a
laminated polishing pad comprising a 1.2 mm-thick upper layer
formed of IC1000 produced by Rodel Inc. and a 1.2 mm-thick lower
layer formed of SUBA400 produced by Rodel Inc.) were used as the
first and second polishing pads 1 and 2.
[0049] The first and second polishing pads 1 and 2 were each
adhered to a polishing surface plate (not shown) by use of a
double-faced pressure sensitive adhesive tape in the case where the
polishing pad was a monolayer product. In the above investigation,
in order that a slurry does not make direct contact with the
polishing surface plate, the first and second polishing pads 1 and
2 were provided with slots 11, small holes 21 or the like by
punching, and then were each adhered to the polishing surface plate
by use of a double-faced pressure sensitive adhesive tape.
Incidentally, when the double-faced pressure sensitive adhesive
tape is adhered to the first and second polishing pads 1 and 2 and
then they are provided with the slots 11, the small holes 21 or the
like by punching, combinations of the polishing pad and the
pressure sensitive adhesive tape with the holes formed also in the
pressure sensitive adhesive tape are obtained. Even where the
double-faced pressure sensitive adhesive tape is thus also provided
with the slots 11 and/or the small holes 21, the effects of the
present invention are not thereby influenced at all.
[0050] On the other hand, the laminated products (laminates)
prepared included those provided with holes piercing through IC1000
only and those with holes piercing through both IC1000 and SUBA400.
Since IC1000 and SUBA400 are adhered by use of the double-faced
pressure sensitive adhesive tape, the laminated product with holes
piercing through IC1000 only can be obtained when IC1000 is
provided with the holes by punching before adhesion, whereas the
laminate product with holes piercing through both IC1000 and
SUBA400 can be easily obtained when formation of the holes by
punching is conducted after adhesion.
[0051] IC1000 was adhered to SUBA400 by use of a double-faced
pressure sensitive adhesive tape. In this case, of the laminate
products with holes piercing through IC1000 only, those with the
double-faced pressure sensitive adhesive tape being not provided
with holes can be obtained when punching is conducted before
adhesion of the double-faced pressure sensitive adhesive tape to
IC1000, whereas those with the double-faced pressure sensitive
adhesive tape being provided with holes can be obtained when
punching is conducted after adhesion of the double-faced pressure
sensitive adhesive tape. The effects of the present invention are
not affected by whether or not the double-faced pressure sensitive
adhesive is provided with holes. In the investigation, the
laminated products with the double-faced pressure sensitive
adhesive tape being free of holes were prepared and used, in view
of that such laminated products are free of penetration of the
slurry to the lower layer formed of SUBA400.
[0052] The laminated products with holes piercing through both
IC1000 and SUBA400 were each adhered to the polishing surface plate
by use of a double-faced pressure sensitive adhesive tape. Of the
laminated products, those with the double-faced pressure sensitive
adhesive tape being not provided with holes can be obtained when
punching is conducted before adhesion of the double-faced pressure
sensitive adhesive tape, whereas those with the double-faced
pressure sensitive adhesive tape being provided with holes can be
obtained when punching is conducted after adhesion of the
double-faced pressure sensitive adhesive tape. The effects of the
present invention are not influenced by whether or not the
double-faced pressure sensitive adhesive tape is provided with
holes. In the investigation, the laminated products with the
double-faced pressure sensitive adhesive tape being free of holes
were prepared and used, in view of that such laminated products are
free of direct contact of the slurry with the polishing surface
plate.
[0053] From Table 1 it is seen that, in the case where the first
polishing pad 1 composed of an IC1000 monolayer had been provided
with slots 11 having a length of not less than 20 mm, no error was
generated in conveying the wafer. However, it should be noted here
that, in the case of the second polishing pad 2 provided with both
small holes 21 as well as slots 11, a conveying error was generated
when the pitch p of the slots 11 reached or exceeded 100 mm.
[0054] In addition, in the case of the first polishing pad 1
composed of an IC1000-SUBA400 laminate and provided with slots 11
piercing through only IC1000, no error was generated in conveying
the wafer when the length of the slots 11 was not less than 20 mm.
In the case of the second polishing pad 2 provided with small holes
21 as well as slots 11, however, a conveying error was generated
when the pitch p of the slots 11 reached or exceeded 100 mm.
[0055] In addition, in the case of the first polishing pad 1
composed of an IC1000-SUBA400 laminate and provided with slots 11
piercing through both IC1000 and SUBA400, no error was generated in
conveying the wafer when the length of the slots 11 was not less
than 20 mm. In the case of the second polishing pad 2 provided with
small holes 21 as well as slots 11, however, a conveying error was
generated when the pitch p of the slots 11 reached or exceeded 100
mm.
[0056] Besides, in the lowermost row of Table 1, the results
obtained with the polishing pads not provided with slots 11 are
shown as a comparative example. As a result, a wafer conveying
error was generated, irrespectively of whether the polishing pad
was a monolayer product or a laminate and whether or not the
polishing pad was provided with small holes. This shows that the
presence of the slots 11 is effective for preventing the wafer
conveying errors from being generated.
[0057] Accordingly, it has been found out that the length of the
slots 11 should be not less than 20 mm. Further, it was also found
that the pitch p in the width direction of the slots should be less
than 100 mm. Besides, the lower limit of the width of the slots 11
was set to be twice the width of the slots 11, taking into account
the rigidity of the polishing pad in the areas between the slots
11.
[0058] Next, an embodiment of slots formed in the first and second
polishing pads according to the present invention will be described
referring to the plan view shown in FIG. 3.
[0059] As shown in FIG. 3, the first polishing pad 1 (the second
polishing pad 2) may be provided with slots 11 which are arranged
radially. While the polishing pad provided with one slot 11 in a
radial direction is shown in the figure, the polishing pad may be
provided with a plurality of slots in a radial direction. Besides,
while small holes 21 are omitted in FIG. 3, the polishing pad may
be provided with small holes 21, as has been described referring to
FIG. 2. Incidentally, the arrangement of the small holes 21 is not
limited to the lattice point pattern, inasmuch as the small holes
21 are formed at predetermined pitches over the entire surface area
of the polishing pad.
[0060] In the polishing pad configured as above-described, by
providing the slots 11 with a sufficient length, for example, a
length greater than the radius of the work (e.g., wafer) and
arranging the slots 11 radially, it is possible to obtain a
structure which ensures that a negative pressure is less liable to
be generated on the wafer. With such slots 11 formed by punching,
the slots 11 can be formed in a comparatively freer shape, as
compared with grooves. This is one of the advantages of the present
configuration.
[0061] Next, another embodiment of the slots formed in the first
and second polishing pads according to the present invention will
be described referring to the plan view shown in FIG. 4.
[0062] As shown in FIG. 4, the first polishing pad 1 (the second
polishing pad 2) may be provided with circular arc-shaped slots 11
which are arranged concentrically, for example. While the case
where two rows of the slots 11 are formed concentrically is shown
in the figure, the slots 11 may be formed in three or more rows.
Besides, while small holes 21 are omitted in FIG. 4, the polishing
pad may be provided with small holes 21, as has been described
referring to FIG. 2. Incidentally, the arrangement of the small
holes 21 is not limited to the lattice point pattern, inasmuch as
the small holes 21 are formed at predetermined pitches over the
entire surface area of the polishing pad.
[0063] In the polishing pad configured as above, by setting the
length of the slots 11 to be, for example, sufficiently greater
than the radius of the work (e.g., wafer) and forming the slots 11
in an arcuate shape, it is possible to obtain a structure which
ensures that a negative pressure is less liable to be generated on
the wafer and that the slurry holding property is enhanced, as
compared with the cases of a parallel or radial arrangement,
whereby the amount of the slurry used can be reduced. With the
slots 11 and the small holes 21 thus formed by punching, they can
be formed in comparatively freer shape, as compared with grooves.
This is one of the advantages of the present configuration.
[0064] Next, a second embodiment of the first polishing pad
according to the present invention will be described referring to
the plan view shown in FIG. 5. In FIG. 5, there is shown a
rectangular polishing pad, as used on a belt-type polishing
apparatus. Incidentally, small holes are omitted in the plan
view.
[0065] As shown in FIG. 5, the polishing pad 5 is provided with a
plurality of slots 11 piercing through the polishing pad 5 in the
thickness direction, the slots 11 being aligned in the row
direction and the column direction. The polishing pad 5 is formed,
for example, of a resin such as foamed urethane and urethane. The
thickness of the polishing pad 5 is comparable to those of ordinary
polishing pads, and is about 0.5 to 3.0 mm, for example. The slots
11 are included in the polishing pad 5, and the length L in the
longitudinal direction thereof is not less than 20 mm. Besides, the
slots 11 are formed at a pitch p which is not less than twice the
length W in the transverse direction thereof (hereinafter referred
to as width) and is less than 100 mm. Incidentally, the spacing d
in the longitudinal direction of the slots 11 is appropriately set;
here, the spacing d is set to be 10 mm, as an example. In addition,
the slots 11 may be formed to be staggered from each other in
either one or both of the row direction and the column
direction.
[0066] Next, a second embodiment of the second polishing pad
according to the present invention will be described referring to
the plan view and the partly enlarged view shown in FIG. 6.
Incidentally, small holes are omitted in the plan view. The symbols
to be used in the following description are the same as those used
in FIGS. 2 and 5.
[0067] As shown in FIG. 6, the polishing pad 6 according to this
second embodiment is the polishing pad 5 as described referring to
FIG. 5 which is provided with the same small holes 21 as described
referring to FIG. 2. Namely, the polishing pad 6 is provided with
slots 11 piercing through the polishing pad 6 in the thickness
direction in the state of being aligned, for example, in the row
direction and the column direction, and is provided also with a
plurality of small holes 21 piercing through the polishing pad 6 in
the thickness direction and having a diameter D of not more than 10
mm, preferably not more than 5 mm. Specifically, the slots 11 are
included in the polishing pad 6, have a length L of not less than
20 mm, and are formed at a pitch p1 which is not less than twice
the width W thereof and is less than 100 mm. Incidentally, the
spacing d in the longitudinal direction of the slots 11 is
appropriately set; here, the spacing d is set to 10 mm, as an
example. Besides, the slots 11 may be formed to be staggered from
each other in either one or both of the row direction and the
column direction.
[0068] Furthermore, the small holes 21 are composed of holes having
a diameter D=1.8 mm, for example, and are uniformly arranged in a
lattice point pattern with pitches p2x=p2y=5 mm. Incidentally, it
is preferable that the small holes 21 are so formed as not to
overlap with the slots 11. In addition, the arrangement of the
small holes 21 is not limited to the lattice point pattern,
inasmuch as the small holes 21 are formed at predetermined pitches
over the entire surface area of the polishing pad.
[0069] While the slots 11 are formed in parallel to the driving
direction of the belt in the above configuration, the direction in
which the slots 11 are arranged may be slant relative to the belt
driving direction or perpendicular to the belt driving
direction.
[0070] While the case where the slots 11 and the small holes 21 are
formed by a single punching operation has been described in the
above-described embodiments, the slots 11 and the small holes 21
may be formed by punching independently from each other. Such a
method promises easier production of the polishing pad in the cases
where it is desired, for example, to enlarge the width of the slots
11 as compared with the pitch of the small holes 21. Specific
examples of such cases include a case where it is desired to form
the small holes 21 at a pitch of 5 mm and to form slots 11 having a
width of 7 mm. Another example is a case where the slots 11 and the
small holes 21 overlap with each other in an area or areas.
Specific example of this is a case where the small holes 21 are
arranged in a lattice point pattern and the slots 11 are arranged
radially or in a circular arc-shaped pattern.
[0071] In addition, where the polishing pad is provided with a
window for optical detection of an end point, it is preferable to
form no hole in the window portion, for ensuring that the light
incident on the wafer is not intercepted. However, provision of the
window with holes would not change the effectiveness of the present
invention.
[0072] While IC1000 has been used as an example of the polishing
pad in the above-described embodiments, the same effects as
above-mentioned can be obtained irrespectively of the material of
the polishing pad, namely, by using a nonwoven fabric-made
polishing pad, sueded polishing pad, or other resin-made polishing
pad or the like which is commercially available. In addition, even
where a polishing pad comprising fixed abrasive grains is used, the
effectiveness of the present invention remains unchanged, and the
same effects as above-mentioned can be obtained.
[0073] Next, the polishing apparatuses according to the present
invention will be described referring to the schematic
configurational perspective views shown in FIGS. 7 and 8.
[0074] The first polishing apparatus is a polishing apparatus for
polishing a surface to be polished of a material to be polished, by
bringing a polishing pad into contact with the surface and into a
frictional motion relative to the surface, wherein the polishing
apparatus comprises one of the above-described polishing pads 1 to
4.
[0075] Specifically, as shown in FIG. 7, the first polishing
apparatus 101 comprises a polishing surface plate 111 which can be
turned in the direction of arrow a, for example. The polishing
surface plate 111 is turned through a rotary shaft 112 connected to
a turning drive which is not shown. In addition, one of the
polishing pads 1 to 4 described above referring to FIGS. 1 to 4 is
mounted on the polishing surface plate 111. Here, the polishing pad
1 was mounted. Now, description will be made referring to the
polishing pad 1. The polishing pad 1 is mounted by a general
polishing pad mounting method, for example, a method using a
pressure sensitive adhesive sheet (inclusive of pressure sensitive
adhesive tape) or a pressure sensitive adhesive. Specifically, the
above-described method is adopted.
[0076] A polishing head 115 is provided at a position opposed to
the polishing surface plate 111 on which the polishing pad 1 is
mounted, generally in opposition to a position deviated from the
center of rotation of the polishing surface plate 111. The
polishing head 115 can be freely raised and lowered. Further, the
polishing pad 115 is turned, for example, in the direction of arrow
b, through a rotary shaft 116 connected to a turning drive which is
not shown. In addition, the surface opposed to the polishing
surface plate 111, of the polishing head 115 is so designed as to
mount a work 301 thereon. As the method for mounting the work,
various methods can be adopted, such as vacuum suction,
electrostatic attraction, adhesion by use of an adhesive, adhesion
by use of a pressure sensitive adhesive sheet, etc. Furthermore, a
nozzle 121 for supplying a polishing slurry 131 (indicated by an
arrow, for convenience) onto the polishing pad 1 is provided on the
upper side of the polishing surface plate 111 and in the vicinity
of the polishing head 115. The polishing slurry 131 is so supplied
as to come between the polishing pad 1 and the work 301 as the
polishing surface plate 111 is turned.
[0077] The first polishing method according to the present
invention will be described below. As an example, the method of
polishing by use of the above-described first polishing apparatus
101 will be described. First, a desired one of the polishing pads 1
to 4 is mounted on the polishing surface plate 111. In addition,
the work 301 is mounted on the polishing head 115. Thereafter, the
polishing slurry 131 is supplied from the nozzle 121 onto the
polishing pad 1, and the polishing surface plate 111 is turned.
Besides, the polishing head 115 is also turned. Then, the work 301
is brought into contact with the polishing pad 1 so as to obtain a
desired processing pressure, whereby the surface to be polished of
the work 301 is polished. As an example of the polishing
conditions, a potassium hydroxide (KOH)-based fumed silica slurry
was used as the polishing slurry 131, the processing pressure was
set at 300 g/cm.sup.2, and the rotating speeds were so set that the
circumferential speed of the polishing pad relative to the work
(e.g., wafer) was 60 m/min. After the polishing is finished, the
work 301 is separated from the polishing pad 1, the supply of the
polishing slurry 131 is stopped, and the turnings of the polishing
surface plate 111 and the polishing head 115 are stopped.
Thereafter, the work 301 may be detached from the polishing head
115. Incidentally, the polished surface of the work 301 may be
washed before the detachment.
[0078] The second polishing apparatus is a belt-type polishing
apparatus for polishing a surface to be polished of a material to
be polished, by bringing a polishing pad into contact with the
surface and into a frictional motion relative to the surface,
wherein the polishing apparatus comprises one of the
above-described polishing pads 5 and 6.
[0079] Specifically, as shown in FIG. 8, the second polishing
apparatus 201 comprises turnable rollers 211 and 212 disposed in
parallel to each other, and the polishing pad 5 or 6 described
above referring to FIG. 5 or 6 of the belt type which is wrapped
around the rollers 211 and 212. Here, as an example, the polishing
pad 5 is used. Description will be made below referring to the
polishing pad 5. The polishing pad 5 is stretched in a
deflection-free state by the rollers 211 and 212. In addition, it
is preferable to provide, between the rollers 211 and 212, a guide
(not shown) which is for preventing the polishing pad from
deflecting toward the inside, i.e., for internally supporting the
polishing pad toward the polishing head 215 and on which the
polishing pad can be freely slid. Besides, at least either one of
the rollers 211 and 212 turned by a turning drive in the direction
of arrow c, for example. This turns the polishing pad 4 in the
direction of arrow d.
[0080] A polishing head 215 is provided opposite to the polishing
surface of the polishing pad 5. The polishing head 215 is designed
to be freely raised and lowered. Further, the polishing head 215 is
turned through a rotary shaft 216 connected to a turning drive
which is not shown. In addition, the surface opposed to the
polishing pad 5, of the polishing head 215 is so designed as to
mount a work 301 thereon. As the method for mounting the work 301,
a variety of methods can be adopted, such as vacuum suction,
electrostatic attraction, adhesion by use of an adhesive, adhesion
by use of a pressure sensitive adhesive sheet, etc. Furthermore, a
nozzle 221 for supplying a polishing slurry 231 (indicated by an
arrow, for convenience) onto the polishing pad 5 is provided on the
upper side of the polishing pad 5 and in the vicinity of the
polishing head 215. The polishing slurry 231 is so supplied as to
come between the polishing pad 5 and the work 301 as the rollers
211 and 212 are turned.
[0081] The second polishing method according to the present
invention will be described below. As an example, the method of
polishing by use of the above-described second polishing apparatus
201 will be described. First, a desired one of the polishing pads 5
and 6 is selected. Here, the polishing pad 5 is used. Therefore,
description will be made below referring to the polishing pad 5. In
addition, a work 301 is mounted on the polishing head 215.
Thereafter, the polishing slurry 231 is supplied from the nozzle
221 onto the polishing pad 5, and the rollers 211 and 212 are
turned to turn the polishing pad 5. Besides, the polishing head 215
is also turned. Then, the work 301 is brought into contact with the
polishing pad 5 so as to obtain a desired processing pressure,
whereby the surface to be polished of the work 301 is polished. As
an example of polishing conditions, a potassium hydroxide
(KOH)-based fumed silica slurry was used as the polishing slurry
231, the processing pressure was set at 300 g/cm.sup.2, and the
rotating speeds were so set that the circumferential speed of the
polishing pad relative to the work (e.g., wafer) was 60 m/min.
After the polishing is over, the work 301 is separated from the
polishing pad 5, the supply of the polishing slurry 231 is stopped,
and the turnings of the polishing pad 5 (the rollers 211 and 212)
and the polishing head 215 are stopped. Thereafter, the work 301
may be detached from the polishing head 215. Incidentally, the
polished surface of the work 301 may be washed before the
detachment.
[0082] The above-described polishing methods are mere examples, and
the polishing conditions can be appropriately modified according to
the object of polishing. In addition, conventionally used polishing
conditions may also be used.
[0083] As has been described above, according to the first
polishing pad of the present invention, the polishing pad is
provided with a plurality of slots piercing through the polishing
pad in the thickness direction, so that it is possible to lower the
hermetic seal property between the surface to be polished and the
polishing pad surface, thereby ensuring that a negative pressure is
less liable to be generated there. Therefore, the work can be
easily removed from the polishing pad surface after completion of
polishing. In addition, since the slots can be formed by punching,
the polishing pad is lower in production cost than a related-art
polishing pad provided with grooves formed by a related-art cutting
operation. Further, since the slots are so formed as to pierce
through the polishing pad in the thickness direction, the slots are
not lost even when the polishing pad is worn, so that the polishing
pad can show a prolonged pad life, as compared with the polishing
pads provided with grooves.
[0084] According to the second polishing pad of the present
invention, the polishing pad is provided with a plurality of holes
piercing through the polishing pad in the thickness direction, and
part of the plurality of holes are composed of slots, so that the
same effects as those of the first polishing pad can be obtained.
Further, since a plurality of holes other than the slots are
present, it is possible to prevent the polishing resistance from
increasing. Furthermore, since the slots can reserve the polishing
liquid therein, the amount of the polishing liquid used can be
reduced, as compared to the cases of the grooved polishing pads
according to the Related Art. In addition, since the plurality of
holes inclusive of the slots can be formed by a single punching
operation, the production cost of the polishing pad is lowered, as
compared with the cases of the related-art polishing pads provided
with grooves by cutting. Furthermore, since the slots are so formed
as to pierce through the polishing pad in the thickness direction,
the slots are not lost even when the polishing pad is worn, so that
the polishing pad can show a prolonged pad life, as compared with
the polishing pads provided with grooves.
[0085] According to the polishing apparatuses of the present
invention, the operating cost of the polishing apparatus can be
lowered, since the polishing pad according to the present invention
which can be produced at a lower cost is mounted thereon. Further,
since the polishing pad according to the present invention is
longer in pad life than the grooved polishing pads according to the
Related Art, it is possible to lower the frequency of replacement
of the polishing pad. As a result, the operating cost of the
polishing apparatus can be lowered. In addition, it is possible to
obtain the functions and effects of the polishing pads according to
the present invention.
[0086] The polishing method according to the present invention
promises a reduction in polishing cost, since the polishing pad
according to the present invention which can be produced at a lower
cost is used in the method. Furthermore, since the polishing pad
according to the present invention is longer in pad life than the
related-art polishing pads provided with grooves, it is possible to
reduce the frequency of replacement of the polishing pad. As a
result, polishing cost can be reduced. In addition, the functions
and effects of the polishing pads according to the present
invention can be obtained.
* * * * *