U.S. patent application number 14/111503 was filed with the patent office on 2014-03-06 for laminated polishing pad.
This patent application is currently assigned to TOYO TIRE & RUBBER CO., LTD.. The applicant listed for this patent is Atsushi Kazuno, Kenji Nakamura. Invention is credited to Atsushi Kazuno, Kenji Nakamura.
Application Number | 20140065932 14/111503 |
Document ID | / |
Family ID | 47041499 |
Filed Date | 2014-03-06 |
United States Patent
Application |
20140065932 |
Kind Code |
A1 |
Kazuno; Atsushi ; et
al. |
March 6, 2014 |
LAMINATED POLISHING PAD
Abstract
The purpose of the present invention is to provide a long-lived
laminated polishing pad wherein a polishing layer is resistant to
detachment from a support layer even when high temperatures are
produced by long periods of polishing. This laminated polishing pad
is characterized that: a polishing layer and a support layer are
laminated together with an adhesive member interposed therebetween;
said adhesive member is either an adhesive layer containing a
polyester-based hot-melt adhesive or double-sided tape that has one
of such adhesive layers on each side of a substrate; and for each
100 weight parts of a polyester-resin base polymer, said
polyester-based hot-melt adhesive contains 2 to 10 weight parts of
an epoxy resin that has at least two glycidyl groups per
molecule.
Inventors: |
Kazuno; Atsushi; (Osaka-shi,
JP) ; Nakamura; Kenji; (Osaka-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kazuno; Atsushi
Nakamura; Kenji |
Osaka-shi
Osaka-shi |
|
JP
JP |
|
|
Assignee: |
TOYO TIRE & RUBBER CO.,
LTD.
Osaka-shi, Osaka
JP
|
Family ID: |
47041499 |
Appl. No.: |
14/111503 |
Filed: |
April 11, 2012 |
PCT Filed: |
April 11, 2012 |
PCT NO: |
PCT/JP2012/059910 |
371 Date: |
October 11, 2013 |
Current U.S.
Class: |
451/59 ; 451/527;
451/539; 51/297 |
Current CPC
Class: |
C09J 163/00 20130101;
B24B 37/22 20130101; C09J 163/00 20130101; C09J 167/00 20130101;
C09J 167/00 20130101; C08L 67/00 20130101; C08L 63/00 20130101;
C08L 63/00 20130101; C08L 67/00 20130101 |
Class at
Publication: |
451/59 ; 451/539;
451/527; 51/297 |
International
Class: |
B24B 37/22 20060101
B24B037/22 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 21, 2011 |
JP |
2011-095270 |
Sep 9, 2011 |
JP |
2011-197277 |
Apr 2, 2012 |
JP |
2012-084023 |
Claims
1. A laminated polishing pad, comprising a support layer, an
adhesive member, and a polishing layer placed on the support layer
with the adhesive member interposed therebetween, wherein the
adhesive member is an adhesive layer containing a polyester-based
hot-melt adhesive or a double-sided tape comprising a backing and
the adhesive layer provided on each of both sides of the backing,
wherein the polyester-based hot-melt adhesive contains 100 parts by
weight of a polyester resin as a base polymer and 2 to 10 parts by
weight of an epoxy resin having two or more glycidyl groups per
molecule.
2. The laminated polishing pad according to claim 1, wherein the
polyester resin is a crystalline polyester resin.
3. The laminated polishing pad according to claim 1, wherein the
polishing layer and the support layer each have an opening, the
laminated polishing pad further comprising a transparent member
placed in the opening of the polishing layer and bonded to the
adhesive member.
4. The laminated polishing pad according to claim 1, wherein the
adhesive layer has a thickness of 10 .mu.m to 200 .mu.m.
5. The laminated polishing pad according to claim 1, wherein the
backing is a resin film having a rate of dimensional change of 1.2%
or less between before and after it is heated at 150.degree. C. for
30 minutes.
6. The laminated polishing pad according to claim 1, wherein the
support layer is a high modulus layer made of a resin film having a
rate of dimensional change of 1.2% or less between before and after
it is heated at 150.degree. C. for 30 minutes.
7. The laminated polishing pad according to claim 1, wherein the
support layer is a cushion layer, the laminated polishing pad
further comprising a resin film provided on one side of the cushion
layer and having a rate of dimensional change of 1.2% or less
between before and after it is heated at 150.degree. C. for 30
minutes.
8. The laminated polishing pad according to claim 1, wherein the
polishing layer has a surface with an arithmetic mean roughness
(Ra) of 1 .mu.m to 15 .mu.m on which the adhesive member is
placed.
9. The laminated polishing pad according to claim 1, having a
shearing stress of 200 N/25 mm square or more at 80.degree. C.
between the polishing layer and the support layer.
10. A laminated polishing pad, comprising a polishing layer, an
adhesive member, a support layer, and a double-sided adhesive sheet
stacked in this order, and further comprising a transparent member
placed in a hole through the polishing layer, the adhesive member,
and the support layer and placed on the double-sided adhesive
sheet, wherein the adhesive member is an adhesive layer containing
a polyester-based hot-melt adhesive or a double-sided tape
comprising a backing and the adhesive layer provided on each of
both sides of the backing, Wherein the polyester-based hot-melt
adhesive contains 100 parts by weight of a polyester resin as a
base polymer and 2 to 10 parts by weight of an epoxy resin having
two or more glycidyl groups per molecule.
11. A method for manufacturing a laminated, polishing pad,
comprising the steps of: stacking, a polishing layer and a support
layer with an adhesive member interposed therebetween to form a
laminated polishing sheet; forming, a through hole in the laminated
polishing sheet; bonding a double-sided adhesive sheet to the
support layer of the laminated polishing sheet having the through
hole; and placing a transparent member in the through hole and on
the double-sided adhesive sheet, wherein the adhesive member is an
adhesive layer containing a polyester-based hot-melt adhesive or a
double-sided tape comprising a backing and the adhesive layer
provided on each of both sides of the backing, wherein the
polyester-based hot-melt adhesive contains 100 parts by weight of a
polyester resin as a base polymer and 2 to 10 parts by weight of an
epoxy resin having two or more glycidyl groups per molecule.
12. A method for manufacturing a semiconductor device, comprising
the step of polishing a surface of a semiconductor wafer using the
laminated polishing pad according to claim 1.
Description
TECHNICAL FIELD
[0001] The present invention relates to a laminated polishing pad
by which the planarizing processing of optical materials such as
lenses, reflecting mirrors and the like, silicon wafers, glass
substrates for hard disks, aluminum substrates, and materials
requiring a high degree of surface planarity such as those in
general metal polishing processing can be carried out stably with
high polishing efficiency. The laminated polishing pad of the
present invention is used particularly preferably in a process of
planarizing a silicone wafer, and a device having an oxide layer, a
metal layer or the like formed on a silicon wafer, before
lamination and formation of the oxide layer, the metal layer or the
like.
BACKGROUND ART
[0002] Production of a semiconductor device involves a step of
forming an electroconductive film on the surface of a wafer to form
a wiring layer by photolithography, etching etc., a step of forming
an interlaminar insulating film on the wiring layer, etc., and an
uneven surface made of an electroconductive material such as metal
and an insulating material is generated on the surface of a wafer
by these steps. In recent years, processing for fine wiring and
multilayer wiring is advancing for the purpose of higher
integration of semiconductor integrated circuits, and accordingly
techniques of planarizing an uneven surface of a wafer have become
important.
[0003] As the method of planarizing an uneven surface of a wafer, a
CMP method is generally used. CMP is a technique wherein while the
surface of a wafer to be polished is pressed against a polishing
surface of a polishing pad, the surface of the wafer is polished
with slurry having abrasive grains dispersed therein. As shown in
FIG. 1, a polishing apparatus used generally in CMP is provided for
example with a polishing platen 2 for supporting a polishing pad 1,
a supporting stand (polishing head) 5 for supporting a polished
material (wafer) 4, a backing material for uniformly pressurizing a
wafer, and a mechanism of feeding an abrasive. The polishing pad 1
is fitted with the polishing platen 2 for example via a
double-sided tape. The polishing platen 2 and the supporting stand
5 are provided with rotating shafts 6 and 7 respectively and are
arranged such that the polishing pad 1 and the polished material 4,
both of which are supported by them, are opposed to each other. The
supporting stand 5 is provided with a pressurizing mechanism for
pushing the polished material 4 against the polishing pad 1.
[0004] Conventional polishing pads for use in high-precision
polishing are generally produced using a polyurethane resin foam
sheet. Unfortunately, such a polyurethane resin foam sheet has
insufficient cushioning properties and therefore can hardly apply
uniform pressure to the entire surface of a wafer, though it has
high local-planarization performance. In general, therefore, a soft
cushion layer is additionally provided on the back side of such a
polyurethane resin foam sheet, and the resulting laminated
polishing pad is used for polishing.
[0005] For example, Patent Document 1 discloses that the polishing
pad wherein a polishing region, a cushion layer and a transparent
support film are laminated in this sequence, and a light
transmission region is provided in an opening penetrating the
polishing region and the cushion layer and on the transparent
support film.
[0006] However, conventional laminated polishing pads, which
usually have a polishing layer and a cushion layer bonded together
with a double-sided tape, have a problem in that a slurry can enter
between the polishing layer and the cushion layer during polishing,
so that the durability of the double-sided tape can decrease and
delamination can easily occur between the polishing layer and the
cushion layer.
[0007] Examples of proposed methods to solve this problem include
the techniques described below.
[0008] Patent Document 2 discloses that a plastic film and a
polishing pad are bonded together with a reactive hot-melt
adhesive.
[0009] Patent Document 3 discloses a polishing pad including a base
layer and a polishing layer bonded together with a hot-melt
adhesive layer.
[0010] Patent Document 4 discloses a technique for forming a
polishing pad including a polishing layer and a base layer bonded
together with a double-sided tape, wherein a water blocking layer
including a hot-melt adhesive is provided between the back side of
the polishing layer and the double-sided tape to block a polishing
slurry.
[0011] Patent Document 5 discloses a polishing pad for
chemical-mechanical polishing comprising: a polishing layer, a
bottom layer, wherein the bottom layer is substantially coextensive
with the polishing layer, and a hot-melt adhesive, wherein the
hot-melt adhesive joins together the polishing layer and the bottom
layer, and the hot-melt adhesive comprises 2 to 18 wt % of EVA and
is substantially resistant to delamination when the polishing layer
attains a temperature of 40.degree. C.
[0012] Unfortunately, the hot-melt adhesives disclosed in Patent
Documents 2 to 5 have a problem in that their heat resistance is
low, and at high temperature caused by polishing for a long period
of time, their tackiness decreases so that delamination can easily
occur between the polishing layer and the cushion layer or the
like.
PRIOR ART DOCUMENTS
Patent Documents
[0013] Patent Document 1: JP-A-2009-172727 [0014] Patent Document
2: JP-A-2002-224944 [0015] Patent Document 3: JP-A-2005-167200
[0016] Patent Document 4: JP-A-2009-95945 [0017] Patent Document 5:
JP-A-2010-525956
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0018] An object of the invention is to provide a long-life
laminated polishing pad that resists delamination between a
polishing layer and a support layer even at high temperature caused
by polishing for a long period of time. In addition to the object,
another object of the invention is to provide a warp-free laminated
polishing pad. A further object of the invention is to provide a
method for manufacturing a semiconductor device using such a
laminated polishing pad.
Means for Solving the Problems
[0019] As a result of earnest investigations to solve the problems,
the inventors have accomplished the invention based on the finding
that the object can be achieved by the laminated polishing pad
shown below.
[0020] Specifically, the invention is directed to a laminated
polishing pad, comprising a support layer, an adhesive member, and
a polishing layer placed on the support layer with the adhesive
member interposed therebetween, wherein the adhesive member is an
adhesive layer containing a polyester-based hot-melt adhesive or a
double-sided tape comprising a backing and the adhesive layer
provided on each of both sides of the backing, wherein the
polyester-based hot-melt adhesive contains 100 parts by weight of a
polyester resin as a base polymer and 2 to 10 parts by weight of an
epoxy resin having two or more glycidyl groups per molecule.
[0021] The inventors have found that when the polyester resin of a
polyester-based hot-melt adhesive used as a material to form an
adhesive layer is crosslinked by addition of 2 to 10 parts by
weight of an epoxy resin having two or more glycidyl groups per
molecule based on 100 parts by weight of the polyester resin as a
base polymer, it is possible to obtain a laminated polishing pad
that has higher adhesive-member durability against "shearing"
during polishing and resists delamination between a polishing layer
and a support layer even at high temperature caused by polishing
for a long period of time.
[0022] If the added amount of the epoxy resin is less than 2 parts
by weight, the adhesive member can have insufficient durability
against "shearing," which occurs during polishing when high
temperature is produced by long-time polishing, so that
delamination can easily occur between the polishing layer and the
support layer. On the other hand, if it is more than 10 parts by
weight, the adhesive layer can have too high hardness and thus
lower tackiness, so that delamination can easily occur between the
polishing layer and the support layer.
[0023] The polyester resin as a base polymer is preferably a
crystalline polyester resin. When a crystalline polyester resin is
used, the adhesive layer will have higher chemical resistance to a
slurry and will be less likely to decrease in adhesive
strength.
[0024] In the laminated polishing pad of the invention, the
polishing layer and the support layer may each have an opening, and
the laminated polishing pad of the invention may further include a
transparent member placed in the opening of the polishing layer and
bonded to the adhesive member.
[0025] The adhesive layer preferably has a thickness of 10 to 200
.mu.m. If the adhesive layer has a thickness of less than 10 .mu.m,
the adhesive member may have insufficient durability against
"shearing" during polishing when high temperature is produced by
polishing for a long period of time, so that delamination may
easily occur between the polishing layer and the support layer. If
the adhesive layer has a thickness of more than 200 .mu.m,
transparency may decrease, so that the polishing pad may have
degraded detection accuracy when it has a transparent member for
use in optically detecting an end point.
[0026] The backing of the double-sided tape is preferably a resin
film having a rate of dimensional change of 1.2% or less between
before and after it is heated at 150.degree. C. for 30 minutes. The
support layer may be a high modulus layer. In this case, the high
modulus layer is preferably made of a resin film having a rate of
dimensional change of 1.2% or less between before and after it is
heated at 150.degree. C. for 30 minutes. The support layer may also
be a cushion layer. In this case, the laminated polishing pad
preferably further includes a resin film provided on one side of
the cushion layer and having a rate of dimensional change of 1.2%
or less between before and after it is heated at 150.degree. C. for
30 minutes.
[0027] The process of bonding a polishing layer and a support layer
together with a hot-melt adhesive involves melting the hot-melt
adhesive by heating. However, this process has a problem in that
heat is also applied to other components such as the support layer
and the backing of a double-sided tape, so that they can be
deformed (thermally shrunk) and a polishing pad as a final product
can be easily warped. Such a warped polishing pad can not only
degrade the appearance of the work but also tend to provide lower
polishing rate uniformity.
[0028] As mentioned above, a resin film having a rate of
dimensional change of 1.2% or less between before and after it is
heated at 150.degree. C. for 30 minutes may be used as the backing
of the double-sided tape, as the high modulus layer, or as the
resin film provided on one side of the cushion layer. In this case,
the polishing pad as a final product can be effectively prevented
from being warped.
[0029] The polishing layer preferably has a surface with an
arithmetic mean roughness (Ra) of 1 to 15 .mu.m, more preferably 3
to 12 .mu.m, on which the adhesive member is placed. When the
surface roughness Ra is adjusted to 1 to 15 .mu.m, a higher
adhesive strength can be provided between the polishing layer and
the adhesive member. If the Ra is less than 1 .mu.m, it may be
difficult to provide sufficiently high adhesive strength between
the polishing layer and the adhesive member. If the Ra exceeds 15
.mu.m, the adhesion between the polishing layer and the adhesive
member may decrease, so that the adhesive strength between them may
tend to decrease.
[0030] The laminated polishing pad preferably has a shearing stress
of 200 N/25 mm square or more, more preferably 250 N/25 mm square
or more, at 80.degree. C. between the polishing layer and the
support layer. During polishing, the temperature of the laminated
polishing pad can rise to about 80.degree. C. When the shearing
stress at 80.degree. C. is 200 N/25 mm square or more, delamination
between the polishing layer and the support layer can be
effectively prevented.
[0031] The laminated polishing pad of the invention may include a
polishing layer, an adhesive member, a support layer, and a
double-sided adhesive sheet stacked in this order, and may further
include a transparent member placed in a hole through the polishing
layer, the adhesive member, and the support layer and placed on the
double-sided adhesive sheet, wherein the adhesive member may be an
adhesive layer containing a polyester-based hot-melt adhesive or
may be a double-sided tape including a backing and the adhesive
layer provided on each of both sides of the backing, wherein the
polyester-based hot-melt adhesive may contain 100 parts by weight
of a polyester resin as a base polymer and 2 to 10 parts by weight
of an epoxy resin having two or more glycidyl groups per
molecule.
[0032] The invention is also directed to a method for manufacturing
a laminated polishing pad, including the steps of: stacking a
polishing layer and a support layer with an adhesive member
interposed therebetween to form a laminated polishing sheet;
forming a through hole in the laminated polishing sheet; bonding a
double-sided adhesive sheet to the support layer of the laminated
polishing sheet having the through hole; and placing a transparent
member in the through hole and on the double-sided adhesive sheet,
wherein the adhesive member is an adhesive layer containing a
polyester-based hot-melt adhesive or a double-sided tape including
a backing and the adhesive layer provided on each of both sides of
the backing, wherein the polyester-based hot-melt adhesive contains
100 parts by weight of a polyester resin as a base polymer and 2 to
10 parts by weight of an epoxy resin having two or more glycidyl
groups per molecule.
[0033] Also, the invention relates to a method for manufacturing a
semiconductor device, comprising a step of polishing a surface of a
semiconductor wafer using the aforementioned laminated polishing
pad.
Effect of the Invention
[0034] The laminated polishing pad of the invention resists
delamination between the polishing layer and the support layer even
at high temperature caused by polishing for a long period of time
because the adhesive member interposed between the polishing layer
and the support layer stacked together contains the specified
polyester-based hot-melt adhesive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 is a schematic diagram showing an example of a
polishing apparatus used in CMP.
[0036] FIG. 2 is a schematic cross-sectional view showing an
example of the laminated polishing pad of the invention.
[0037] FIG. 3 is a schematic cross-sectional view showing another
example of the laminated polishing pad of the invention.
MODE FOR CARRYING OUT THE INVENTION
[0038] In the invention, the polishing layer is not restricted as
long as it is a foam containing fine cells. For example, the
material for the foam may be one of or a blend of two or more of
polyurethane resin, polyester resin, polyamide resin, acrylic
resin, polycarbonate resin, halogen-containing resin (such as
polyvinyl chloride, polytetrafluoroethylene and polyvinylidene
fluoride etc.), polystyrene, olefin resin (such as polyethylene and
polypropylene etc.), epoxy resin, and photosensitive resin.
Polyurethane resin is particularly preferred as a material for
forming the polishing layer because polyurethane resin has good
wear resistance and because urethane polymers having desired
physical properties can be easily obtained through changing the
composition of raw materials in various manners. Hereinafter,
polyurethane resin will be described as a typical example of the
material for the foam.
[0039] The polyurethane resin contains an isocyanate component, a
polyol component (high-molecular-weight polyol,
low-molecular-weight polyol etc.) and a chain extender.
[0040] As the isocyanate component, a compound known in the field
of polyurethane can be used without particular limitation. The
isocyanate component includes, for example, aromatic diisocyanates
such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate,
2,2'-diphenyl methane diisocyanate, 2,4'-diphenyl methane
diisocyanate, 4,4'-diphenyl methane diisocyanate, 1,5-naphthalene
diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate,
p-xylylene diisocyanate and m-xylylene diisocyanate, aliphatic
diisocyanates such as ethylene diisocyanate, 2,2,4-trimethyl
hexamethylene diisocyanate and 1,6-hexamethylene diisocyanate, and
cycloaliphatic diisocyanates such as 1,4-cyclohexane diisocyanate,
4,4'-dicyclohexyl methane diisocyanate, isophorone diisocyanate and
norbornane diisocyanate. These may be used alone or as a mixture of
two or more thereof.
[0041] As the high-molecular-weight polyol, a compound known in the
field of polyurethane can be used without particular limitation.
The high-molecular-weight polyol includes, for example, polyether
polyols represented by polytetramethylene ether glycol and
polyethylene glycol, polyester polyols represented by polybutylene
adipate, polyester polycarbonate polyols exemplified by reaction
products of polyester glycols such as polycaprolactone polyol and
polycaprolactone with alkylene carbonate, polyester polycarbonate
polyols obtained by reacting ethylene carbonate with a multivalent
alcohol and reacting the resulting reaction mixture with an organic
dicarboxylic acid, and polycarbonate polyols obtained by ester
exchange reaction of a polyhydroxyl compound with aryl carbonate.
These may be used singly or as a mixture of two or more
thereof.
[0042] Besides the above high-molecular-weight polyol described in
the above as a polyol component, it is preferred to concomitantly
use a low-molecular-weight polyol such as ethyleneglycol,
1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol,
1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,6-hexanediol,
neopentylglyol, 1,4-cyclohexanedimethanol,
3-methyl-1,5-pentanediol, diethyleneglycol, triethyleneglycol,
1,4-bis(2-hydroxyethoxy)benzene, trimethylolpropane, glycerin,
1,2,6-hexanetriol, pentaerythritol, tetramethylol cyclohexane,
methylglucoside, sorbitol, mannitol, dulcitol, sucrose,
2,2,6,6-tetrakis(hydroxymethyl)cyclohexanol, diethanolamine,
N-methyldiethanolamine and triethanol amine. Low-molecular-weight
polyamine such as ethylenediamine, tolylenediamine,
diphenylmethanediamine, and diethylenetriamine may be used. Alcohol
amine such as monoethanol amine, 2-(2-aminoethylamino) ethanol and
monopropanol amine may be used. These may be used singly or in
combination of two or more kinds. The content of the
low-molecular-weight polyol, the low-molecular-weight polyamine, or
other materials is not particularly limited, and may be
appropriately determined depending on the properties required of
the polishing pad (polishing layer) to be manufactured.
[0043] In the case where a polyurethane resin foam is produced by
means of a prepolymer method, a chain extender is used in curing of
a prepolymer. A chain extender is an organic compound having at
least two active hydrogen groups and examples of the active
hydrogen group include: a hydroxyl group, a primary or secondary
amino group, a thiol group (SH) and the like. Concrete examples of
the chain extender include: polyamines such as
4,4'-methylenebis(o-chloroaniline) (MOCA),
2,6-dichloro-p-phenylenediamine,
4,4'-methylenebis(2,3-dichloroaniline),
3,5-bis(methylthio)-2,4-toluenediamine,
3,5-bis(methylthio)-2,6-toluenediamine,
3,5-diethyltoluene-2,4-diamine, 3,5-diethyltoluene-2,6-diamine,
trimethylene glycol-di-p-aminobenzoate, polytetramethylene
oxide-di-p-aminobenzoate,
4,4'-diamino-3,3',5,5'-tetraethyldiphenylmethane,
4,4'-diamino-3,3'-diisopropyl-5,5'-dimethyldiphenylmethane,
4,4'-diamino-3,3',5,5'-tetraisopropyldiphenylmethane,
1,2-bis(2-aminophenylthio)ethane,
4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane,
N,N'-di-sec-butyl-4,4'-diaminophenylmethane,
3,3'-diethyl-4,4'-diaminodiphenylmethane, m-xylylenediamine,
N,N'-di-sec-butyl-p-phenylenediamine, m-phenylenediamine and
p-xylylenediamine; the low-molecules-weight polyol; and the
low-molecular-weight polyamine. The chain extenders described above
may be used either alone or in mixture of two kinds or more.
[0044] A ratio between an isocyanate component, a polyol component
and a chain extender in the invention can be altered in various
ways according to molecular weights thereof, desired physical
properties of a polishing pad and the like. In order to obtain a
polishing pad with desired polishing characteristics, a ratio of
the number of isocyanate groups in an isocyanate component relative
to a total number of active hydrogen groups (hydroxyl
groups-1-amino groups) in a polyol component and a chain extender
is preferably in the range of from 0.80 to 1.20 and more preferably
in the range of from 0.99 to 1.15. When the number of isocyanate
groups is outside the aforementioned range, there is a tendency
that curing deficiency is caused, required specific gravity and
hardness are not obtained, and polishing property is
deteriorated.
[0045] A polyurethane resin foam can be produced by applying a
melting method, a solution method or a known polymerization
technique, among which preferable is a melting method,
consideration being given to a cost, a working environment and the
like.
[0046] Manufacture of a polyurethane resin foam is enabled by means
of either a prepolymer method or a one shot method, of which
preferable is a prepolymer method in which an isocyanate-terminated
prepolymer is synthesized from an isocyanate component and a polyol
component in advance, with which a chain extender is reacted since
physical properties of an obtained polyurethane resin is
excellent.
[0047] Manufacturing methods of a polyurethane resin foam include:
a method in which hollow beads are added, a mechanical foaming
method, a chemical foaming method and the like.
[0048] Particularly, preferred is a mechanical foaming method using
a silicone-based surfactant which is a copolymer of
polyalkylsiloxane and polyether and has no an active hydrogen
group.
[0049] A stabilizer such as antioxidant, a lubricant, a pigment, a
filler, an antistatic agent and other additives may be added, as
needed.
[0050] The polyurethane resin foam may be of a closed cell type or
an open cell type.
[0051] Production of the polyurethane resin foam may be in a batch
system where each component is weighed out, introduced into a
vessel and mixed or in a continuous production system where each
component and a non-reactive gas are continuously supplied to, and
stirred in, a stirring apparatus and the resulting forming reaction
liquid is transferred to produce molded articles.
[0052] A manufacturing method of a polyurethane resin foam may be
performed in ways: in one of which a prepolymer which is a raw
material from which a polyurethane foam is made is put into a
reactor, thereafter a chain extender is mixed into the prepolymer,
the mixture is agitated, thereafter the mixture is cast into a mold
with a predetermined size to thereby prepare a block and the block
is sliced with a slicer like a planer or a band saw; and in another
of which in the step of casting into the mold, a thin sheet may be
directly produced. Besides, a still another way may be adopted in
which a resin of raw material is melted, the melt is extruded
through a T die to thereby mold a polyurethane resin foam directly
in the shape of a sheet.
[0053] An average cell diameter of a polyurethane resin foam is
preferably in the range of from 30 to 80 .mu.m and more preferably
in the range of from 30 to 60 .mu.m. If an average cell diameter
falls outside the range, a tendency arises that a polishing rate is
decreased and a planarity of an object to be polished (a wafer)
after polishing is reduced.
[0054] Preferably, the polyurethane resin foam has a specific
gravity ranging from 0.5 to 1.3. When the specific gravity is less
than 0.5, the surface strength of the polishing layer decreases, so
that the planarity of the object to be polished tends to decrease.
When the specific gravity is larger than 1.3, the cell number on
the surface of the polishing layer decreases, so that the polishing
rate tends to decrease despite excellent planarity.
[0055] Preferably, the polyurethane resin foam has a hardness
measured by ASKER D hardness meter, ranging from 40 to 75 degrees.
When the ASKER D hardness is less than 40 degrees, the planarity of
the object to be polished decreases, while when the hardness is
more than 75 degrees, the uniformity of the object to be polished
tends to decrease despite excellent planarity.
[0056] Preferably, a polishing surface of the polishing layer,
which comes into contact with an object to be polished have an
asperity structure provided for retaining and refreshing a slurry.
A polishing layer made of a foam has a number of openings in the
polishing surface, and has a function of retaining and refreshing a
slurry. By forming an asperity structure on the polishing surface,
it is possible to conduct retention and refreshment of the slurry
more efficiently, and to prevent the object to be polished from
breaking due to adsorption of the material to be polished. The
shape of the asperity structure is not particularly limited insofar
as it is able to retain and refresh a slurry, and for example, XY
grating groove, concentric ring groove, through-hole,
non-through-hole, polygonal column, circular cylinder, spiral
groove, eccentric ring groove, radial groove, and combination
thereof can be recited. These asperity structures generally have
regularity, however, groove pitch, groove width, groove depth and
the like may be varied by a certain range for achieving desired
retention and refreshment of slurry.
[0057] The polishing layer may have any shape such as a circular
shape or an elongated shape. The size of the polishing layer may be
appropriately adjusted depending on the polishing apparatus to be
used. When the polishing layer is circular, it may have a diameter
of about 30 to about 150 cm, and when the polishing layer has an
elongated shape, it may have a length of about 5 to about 15 m and
a width of about 60 to about 250 cm.
[0058] The thickness of the polishing layer is generally, but is
not limited to, about 0.8 to 4 mm, and preferably 1.2 to 2.5
mm.
[0059] The laminated polishing pad of the invention is made by
bonding the polishing layer and the support layer together with the
adhesive member.
[0060] The support layer is provided to supplement the
characteristics of the polishing layer. The support layer to be
used may be a layer (cushion layer) having an elastic modulus lower
than that of the polishing layer or may be a layer (high modulus
layer) having an elastic modulus higher than that of the polishing
layer. The cushion layer is necessary for CMP to achieve both good
planarity and good uniformity, which are usually in a trade-off
relationship. The term "planarity" refers to the flatness of a
patterned part formed by polishing an object to be polished having
fine irregularities, which are produced in a patterning process.
The term "uniformity" refers to the entire uniformity of an object
to be polished. The characteristics of the polishing layer
contribute to an improvement in planarity, and the characteristics
of the cushion layer contribute to an improvement in uniformity.
The high modulus layer is used to improve the planarizing
characteristics of the polishing pad when a relatively soft
polishing layer is used in order to suppress scratching in CMP. The
use of the high modulus layer makes it possible to suppress
excessive polishing of the edge of an object to be polished.
[0061] Examples of the cushion layer include nonwoven fiber fabrics
such as polyester nonwoven fabrics, nylon nonwoven fabrics, and
acrylic nonwoven fabrics; resin impregnated nonwoven fabrics such
as polyurethane impregnated polyester nonwoven fabrics; polymeric
resin foams such as polyurethane foams and polyethylene foams;
rubber resins such butadiene rubber and isoprene rubber; and
photosensitive resins, etc.
[0062] The thickness of the cushion layer is preferably, but not
limited to, 300 to 1,800 .mu.m, more preferably 700 to 1,400
.mu.m.
[0063] When the support layer is the cushion layer, a resin film
having a rate of dimensional change of 1.2% or less between before
and after it is heated at 150.degree. C. for 30 minutes is
preferably provided on one side of the cushion layer (on the
polishing platen side). The resin film more preferably has a rate
of dimensional change of 0.8% or less, even more preferably 0.4% or
less. Examples of the resin film having such properties include a
polyethylene terephthalate film, a polyethylene naphthalate film,
and a polyimide film each having undergone thermal shrinkage
treatment.
[0064] The thickness of the resin film is preferably, but not
limited to, 10 to 200 .mu.m, more preferably 15 to 55 .mu.m, in
view of stiffness, dimensional stability during heating, and other
properties.
[0065] Examples of the high modulus layer include a metal sheet, a
resin film, and the like. Examples of the resin film include
polyester films such as polyethylene terephthalate films and
polyethylene naphthalate films; polyolefin films such as
polyethylene films and polypropylene films; nylon films; and
polyimide films, etc.
[0066] A resin film having a rate of dimensional change of 1.2% or
less between before and after it is heated at 150.degree. C. for 30
minutes is preferably used as the high modulus layer. The resin
film more preferably has a rate of dimensional change of 0.8% or
less, even more preferably 0.4% or less. Examples of the resin film
having such properties include a polyethylene terephthalate film, a
polyethylene naphthalate film, and a polyimide film each having
undergone thermal shrinkage treatment.
[0067] The thickness of the high modulus film is preferably, but
not limited to, 10 to 200 .mu.m, more preferably 15 to 55 .mu.m, in
view of stiffness, dimensional stability during heating, and other
properties.
[0068] The adhesive member to be used is an adhesive layer
containing a polyester-based hot-melt adhesive or a double-sided
tape including a backing and such an adhesive layer provided on
each of both sides of the backing.
[0069] The polyester-based hot-melt adhesive contains at least a
polyester resin as a base polymer and an epoxy resin having two or
more glycidyl groups per molecule, in which the epoxy resin is a
crosslinking component.
[0070] The polyester resin may be any known polyester resin which
is obtained by condensation polymerization of an acid and a polyol
or other polymerization processes. In particular, the polyester
resin is preferably a crystalline polyester resin.
[0071] Examples of the acid include aromatic dicarboxylic acids,
aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids,
etc. These may be used alone or in combination of two or more.
[0072] Examples of aromatic dicarboxylic acids include terephthalic
acid, isophthalic acid, phthalic anhydride, .alpha.-naphthalene
dicarboxylic acid, .beta.-naphthalene dicarboxylic acid, and their
ester forms, etc.
[0073] Examples of aliphatic dicarboxylic acids include succinic
acid, glutaric acid, adipic acid, pimelic acid, suberic acid,
azelaic acid, sebacic acid, undecylenic acid, dodecanedioic acid,
and their ester forms, etc.
[0074] Examples of alicyclic dicarboxylic acids include
1,4-cyclohexane dicarboxylic acid, tetrahydrophthalic anhydride,
hexahydrophthalic anhydride, etc.
[0075] An unsaturated acid such as maleic acid, fumaric acid, or
dimer acid, a polycarboxylic acid such as trimellitic acid or
pyromellitic acid, or other acids may also be used as the acid in
combination with any of the above acids.
[0076] Examples of the polyol include dihydric alcohols such as
aliphatic glycols and alicyclic glycols, and polyhydric alcohols.
These may be used alone or in combination of two or more.
[0077] Examples of aliphatic glycols include ethylene glycol,
1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol,
1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol,
1,9-nonanediol, neopentyl glycol, 3-methylpentanediol,
2,2,3-trimethylpentanediol, diethylene glycol, triethylene glycol,
dipropylene glycol, etc.
[0078] Examples of alicyclic glycols include
1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.
[0079] Examples of polyhydric alcohols include glycerin,
trimethylolethane, trimethylolpropane, pentaerythritol, etc.
[0080] The crystalline polyester resin can be synthesized by known
methods. Examples include melt polymerization methods including
adding raw materials and a catalyst and heating the mixture at a
temperature equal to or higher than the melting point of the
desired product, solid-phase polymerization methods including
performing polymerization at a temperature equal to or lower than
the melting point of the desired product, and solution
polymerization methods using a solvent, etc. Any of these methods
may be used.
[0081] The crystalline polyester resin preferably has a melting
point of 100 to 200.degree. C. If the melting point is lower than
100.degree. C., the adhesive strength of the hot-melt adhesive can
be lowered by heat generated during polishing. If the melting point
is higher than 200.degree. C., a higher temperature will be needed
to melt the hot-melt adhesive, which may warp the laminated
polishing pad and tend to have an adverse effect on the polishing
characteristics.
[0082] The crystalline polyester resin preferably has a number
average molecular weight of 5,000 to 50,000. If the number average
molecular weight is less than 5,000, the hot-melt adhesive may have
lower mechanical characteristics, so that a sufficient level of
tackiness and durability may fail to be obtained. If the number
average molecular weight is more than 50,000, a production failure
such as gelation may occur in the process of synthesizing the
crystalline polyester resin, or the hot-melt adhesive may tend to
have lower performance.
[0083] Examples of the epoxy resin include aromatic epoxy resins
such as bisphenol A type epoxy resins, brominated bisphenol A type
epoxy resins, bisphenol type epoxy resins, bisphenol AD type epoxy
resins, stilbene type epoxy resins, biphenyl type epoxy resins,
bisphenol A novolac type epoxy resins, cresol novolac type epoxy
resins, diaminodiphenylmethane type epoxy resins, and
polyphenyl-based epoxy resins such as
tetrakis(hydroxyphenyl)ethane-based epoxy resins,
fluorene-containing epoxy resins, and epoxy resins containing a
triglycidyl isocyanurate moiety or a heteroaromatic ring (such as a
triazine ring); and non-aromatic epoxy resins such as aliphatic
glycidyl ether type epoxy resins, aliphatic glycidyl ester type
epoxy resins, alicyclic glycidyl ether type epoxy resins, and
alicyclic glycidyl ester type epoxy resins. These may be used alone
or in combination of two or more.
[0084] Among them, cresol novolac type epoxy resins are preferably
used in view of tackiness to the polishing layer during
polishing.
[0085] The epoxy resin is necessarily added in an amount of 2 to 10
parts by weight, preferably in an amount of 3 to 7 parts by weight,
to 100 parts by weight of the polyester resin as a base
polymer.
[0086] The polyester-based hot-melt adhesive may also contain known
additives such as a softener such as an olefin resin, a tackifier,
a filler, a stabilizer, and a coupling agent. The adhesive may also
contain a known inorganic filler such as talc and other
materials.
[0087] The polyester-based hot-melt adhesive can be prepared by
mixing at least the polyester resin and the epoxy resin and
optional materials by any method. For example, the polyester-based
hot-melt adhesive can be prepared by mixing the respective raw
materials using an extruder such as a mono-screw extruder, a
co-rotating intermeshing parallel twin screw extruder, a
counter-rotating intermeshing parallel twin screw extruder, a
counter-rotating intermeshing inclined twin screw extruder, a
non-intermeshing twin screw extruder, an incompletely intermeshing
twin screw extruder, a co-kneader extruder, a planetary gear
extruder, a transfer mixing extruder, a ram extruder, or a roller
extruder, or a kneader, etc.
[0088] The polyester-based hot-melt adhesive preferably has a
melting point of 100 to 200.degree. C.
[0089] The polyester-based hot-melt adhesive preferably has a
specific gravity of 1.1 to 1.3.
[0090] The polyester-based hot-melt adhesive preferably has a melt
flow index of 16 to 26 g/10 minutes under the conditions of
150.degree. C. and a load of 2.16 kg.
[0091] The polyester-based hot-melt adhesive may be used in any
form, such as in the form of a pellet, a powder, a sheet, a film,
or a solvent solution. In the invention, however, the
polyester-based hot-melt adhesive is preferably used in the form of
a sheet or a film.
[0092] The polishing layer and the support layer may be bonded
together by any method. For example, the polishing layer and the
support layer may be bonded together by a method including using
the polyester-based hot-melt adhesive to form an adhesive layer on
the support layer, melting the adhesive layer by heat from a
heater, and then press-laminating the polishing layer onto the
molten adhesive layer.
[0093] The adhesive layer preferably has a thickness of 10 to 200
.mu.m, more preferably 25 to 125 .mu.m.
[0094] A double-sided tape including a backing and the adhesive
layers provided on both sides of the backing may also be used
instead of the adhesive layer. The backing can prevent a slurry
from permeating to the support layer side, so that delamination
between the support layer and the adhesive layer can be
prevented.
[0095] The backing may be a resin film or the like. Examples of the
resin film include polyester films such as polyethylene
terephthalate films and polyethylene naphthalate films; polyolefin
films such as polyethylene films and polypropylene films; nylon
films; and polyimide films, etc. Among them, polyester films are
preferably used, which have high ability to prevent water
permeation.
[0096] The backing to be used is preferably a resin film having a
rate of dimensional change of 1.2% or less between before and after
it is heated at 150.degree. C. for 30 minutes. The resin film more
preferably has a rate of dimensional change of 0.8% or less, even
more preferably 0.4% or less. Examples of the resin film having
such properties include a polyethylene terephthalate film, a
polyethylene naphthalate film, and a polyimide film each having
undergone thermal shrinkage treatment.
[0097] The surface of the backing may be subjected to an
adhesion-facilitating treatment such as a corona treatment or a
plasma treatment.
[0098] The thickness of the backing is preferably, but not limited
to, 10 to 200 .mu.m, more preferably 15 to 55 .mu.m, in view of
transparency, flexibility, stiffness, dimensional stability during
heating, and other properties.
[0099] When the double-sided tape is used, the thickness of the
adhesive layer is preferably from 10 to 200 .mu.m, more preferably
from 25 to 125 .mu.m.
[0100] The laminated polishing pad of the invention may also be
provided with a double-sided tape on its side to be attached to a
platen.
[0101] FIG. 2 is a schematic cross-sectional view showing an
example of the laminated polishing pad of the invention. A
polishing layer 8 is provided with a transparent member 9 for use
in optically detecting an end point during polishing. The
transparent member 9 is fixed by being fit in an opening 10 formed
in the polishing layer 8 and being bonded to an adhesive member 11
under the polishing layer 8. When the transparent member 9 is
placed in the polishing layer 8, an opening 13 for transmitting
light is preferably formed in the support layer 12.
[0102] The adhesive member 11 of the invention has the function of
preventing a slurry from leaking to the support layer 12 side
(water-blocking function) when the slurry enters between the
polishing layer 8 and the transparent member 9. In addition, when
the slurry enters between the polishing layer 8 and the transparent
member 9, the adhesive strength of the adhesive member 11 of the
invention will not reduced by the slurry, and thus the adhesive
member 11 of the invention can effectively prevent delamination
between the polishing layer 8 and the support layer 12.
[0103] FIG. 3 is a schematic cross-sectional view showing another
example of the laminated polishing pad of the invention. The
laminated polishing pad 1 includes a polishing layer 8, an adhesive
member 11, a support layer 12, and a double-sided adhesive sheet
14, which are stacked in this order, and further includes a
transparent member 9 that is provided on the double-sided adhesive
sheet 14 and inserted in a through hole 15 formed through the
polishing layer 8, the adhesive member 11, and the support layer
12.
[0104] The double-sided adhesive sheet 14 is generally what is
called a double-sided tape, which includes a backing and adhesive
layers provided on both sides of the backing. The double-sided
adhesive sheet 14 is used to bond the laminated polishing pad 1 to
a polishing platen 2.
[0105] For example, the laminated polishing pad 1 can be
manufactured by the following process. First, the polishing layer 8
and the support layer 12 are stacked with the adhesive member 11
interposed therebetween to form a laminated polishing sheet. The
through hole 15 is formed in the resulting laminated polishing
sheet. The double-sided adhesive sheet 14 is bonded to the support
layer 12 of the laminated polishing sheet having the through hole
15. Subsequently, the transparent member 9 is inserted into the
through hole 15 and placed on the double-sided adhesive sheet 14.
Alternatively, the double-sided adhesive sheet 14 may be bonded to
the support layer 12 and the transparent member 9 after the
transparent member 9 is inserted into the through hole 15.
[0106] The surface level of the transparent member 9 is preferably
equal to that of the polishing layer 8 or preferably lower than
that of the polishing layer 8. If the surface level of the
transparent member 9 is higher than that of the polishing layer 8,
the projection part may scratch the material being polished. In
addition, the transparent member 9 may be deformed by stress
applied during polishing, so that large optical distortion may
occur and reduce the accuracy of the optical detection of a
polishing end point.
[0107] A semiconductor device is fabricated after operation in a
step of polishing a surface of a semiconductor wafer with a
laminated polishing pad. The term, a semiconductor wafer, generally
means a silicon wafer on which a wiring metal and an oxide layer
are stacked. No specific limitation is imposed on a polishing
method of a semiconductor wafer or a polishing apparatus, and
polishing is performed with a polishing apparatus equipped, as
shown in FIG. 1, with a polishing platen 2 supporting a laminated
polishing pad 1, a polishing head 5 holding a semiconductor wafer
4, a backing material for applying a uniform pressure against the
wafer and a supply mechanism of a polishing agent 3. The laminated
polishing pad 1 is mounted on the polishing platen 2 by adhering
the pad to the platen with a double-sided adhesive tape. The
polishing platen 2 and the polishing head 5 are disposed so that
the laminated polishing pad 1 and the semiconductor wafer 4
supported or held by them oppositely face each other and provided
with respective rotary shafts 6 and 7. A pressure mechanism for
pressing the semiconductor wafer 4 to the laminated polishing pad 1
is installed on the polishing head 5 side. During polishing, the
semiconductor wafer 4 is polished by being pressed against the
laminated polishing pad 1 while the polishing platen 2 and the
polishing head 5 are rotated and a slurry is fed. No specific
limitation is placed on a flow rate of the slurry, a polishing
load, a polishing platen rotation number and a wafer rotation
number, which are properly adjusted.
[0108] Protrusions on the surface of the semiconductor wafer 4 are
thereby removed and polished flatly. Thereafter, a semiconductor
device is produced therefrom through dicing, bonding, packaging
etc. The semiconductor device is used in an arithmetic processor, a
memory etc.
EXAMPLES
[0109] Description will be given of the invention with examples,
while the invention is not limited to description in the
examples.
[0110] [Methods for Measurement and Evaluation]
[0111] (Measurement of Number Average Molecular Weight)
[0112] The number average molecular weight was measured as a
polystyrene-equivalent value by GPC (gel permeation chromatography)
with standard polystyrene.
GPC system: LC-10A manufactured by Shimadzu Corporation Columns:
three columns PLgel (5 .mu.m, 500 .ANG.), PLgel (5 .mu.m, 100
.ANG.) and PLgel (5 .mu.m, 50 .ANG.) each manufactured by Polymer
Laboratories were coupled and used. Flow rate: 1.0 ml/minute
Concentration: 1.0 g/l
[0113] Injection volume: 40 .mu.l Column temperature: 40.degree. C.
Eluent: tetrahydrofuran
[0114] (Measurement of Melting Point)
[0115] The melting point of the polyester-based hot-melt adhesive
was measured at a rate of temperature rise of 20.degree. C./minute
using TOLEDO DSC822 (manufactured by Mettler-Toledo International
Inc.).
[0116] (Measurement of Specific Gravity)
[0117] The measurement was performed according to JIS Z 8807-1976.
A 4 cm.times.8.5 cm adhesive layer strip (of arbitrary thickness)
was cut from the polyester-based hot-melt adhesive and used as a
sample for the specific gravity measurement. The sample was allowed
to stand in an environment at a temperature of 23.degree.
C..+-.2.degree. C. and a humidity of 50%.+-.5% for 16 hours. The
sample was measured for specific gravity using a specific gravity
meter (manufactured by Sartorius AG).
[0118] (Measurement of Melt Flow Index (MI))
[0119] The melt flow index of the polyester-based hot-melt adhesive
was measured according to ASTM-D-1238 under the conditions of
150.degree. C. and 2.16 kg.
[0120] (Measurement of Shearing Stress)
[0121] Three 25 mm.times.25 mm sample pieces were cut from the
resulting laminated polishing pad. The polishing layer and the
support layer of each sample were pulled from each other at a
pulling rate of 300 mm/minute when the shearing stress (N/25 mm
square) was measured. Table 1 shows the average of the measurements
for the three samples. In the measurement, the samples were also
observed for the state of peeling. Also after polishing was
performed for 60 hours using the resulting laminated polishing pad
under the conditions shown below, the shearing stress was measured
using the same method, and the state of peeling was observed.
[0122] (Evaluation of uniformity of polishing rate)
[0123] The resulting laminated polishing pad was used in a
polishing apparatus SPP600S (manufactured by Okamoto Machine Tool
Works, Ltd.) when polishing rate uniformity was evaluated. An 8
inch silicon wafer having a 10,000 .ANG. tungsten film formed
thereon was polished for 60 seconds per wafer, and the polishing
rate was calculated from the resulting amount of polishing. The
polishing was performed for 60 hours while the wafer was replaced
by new ones. The thickness of the tungsten film was measured using
a non-contact resistivity measurement system (Model-NC-80M
manufactured by NAPSON CORPORATION). The initial polishing rate
uniformity (%) was calculated from the formula below using the
maximum polishing rate, the minimum polishing rate, and the average
polishing rate each obtained for the surface (121 points) of the
fifth wafer from the start of polishing. After 60 hours, the wafer
polishing rate uniformity (%) was also calculated in the same
way.
Uniformity(%)={(the maximum polishing rate-the minimum polishing
rate)/2}.times.the average polishing rate.times.100
[0124] The polishing conditions were as follows. W2000
(manufactured by Cabot Corporation) was diluted twice with
ultrapure water. Two % by weight of hydrogen peroxide water was
added to the resulting dilution. The resulting slurry was added at
a flow rate of 150 ml/minute during the polishing, in which the
polishing load, the polishing platen rotation speed, and the wafer
rotation speed were 5 psi, 120 rpm, and 120 rpm, respectively.
Before the polishing, the surface of the polishing pad was dressed
for 20 seconds using a dresser (Type M100 manufactured by Asahi.
Diamond Industrial Co., Ltd.). The dressing conditions were as
follows: a dressing load of 10 g/cm.sup.2, a polishing platen
rotation speed of 30 rpm, and a dresser rotation speed of 15
rpm.
[0125] (Measurement of Rate of Dimensional Change)
[0126] The rate of dimensional change between before and after the
resin film was heated at 150.degree. C. for 30 minutes was measured
according to JIS C 2318.
[0127] (Measurement of Warpage of Laminated Polishing Pad)
[0128] The resulting laminated polishing pad was placed on a
horizontal table, and the height (the amount of lifting) of the
most warped end part of the pad was measured from the table.
[0129] (Measurement of Shearing Stress)
[0130] Three 25 mm.times.25 mm sample pieces were cut from the
resulting laminated polishing pad. In a thermostatic chamber
adjusted to 80.degree. C., the polishing layer and the support
layer of each sample were pulled from each other at a pulling rate
of 300 mm/minute when the shearing stress (N/25 mm square) was
measured. Table 3 shows the average of the measurements for the
three samples. In the measurement, the samples were also observed
for the state of peeling.
Production Example 1
[0131] (Preparation of Polishing Layer)
[0132] To a vessel were added 1,229 parts by weight of toluene
diisocyanate (a mixture of
2,4-diisocyanate/2,6-diisocyanate=80/20), 272 parts by weight of
4,4'-dicyclohexylmethane diisocyanate, 1,901 parts by weight of
polytetramethylene ether glycol with a number average molecular
weight of 1,018, and 198 parts by weight of diethylene glycol, and
allowed to react at 70.degree. C. for 4 hours, so that an
isocyanate-terminated prepolymer was obtained.
[0133] To a polymerization vessel were added 100 parts by weight of
the prepolymer and 3 parts by weight of a silicone surfactant
(SH-192 manufactured by Dow Corning Toray Co., Ltd.) and mixed. The
mixture was adjusted to 80.degree. C. and degassed under reduced
pressure. Subsequently, the reaction system was vigorously stirred
for about 4 minutes with a stirring blade at a rotational speed of
900 rpm so that air bubbles were incorporated into the reaction
system. Thereto was added 26 parts by weight of MOCA (CUAMINE-MT,
manufactured by IHARA CHEMICAL INDUSTRY CO., LTD.), whose
temperature was adjusted to 120.degree. C. in advance. The liquid
mixture was stirred for about 1 minute and then poured into a
pan-shaped open mold (casting vessel). At the point when the liquid
mixture lost its fluidity, it was placed in an oven, and subjected
to post curing at 100.degree. C. for 16 hours, so that a
polyurethane resin foam block was obtained.
[0134] While heated at about 80.degree. C., the polyurethane resin
foam block was sliced using a slicer (VGW-125 manufactured by
AMITEC Corporation), so that a polyurethane resin foam sheet (50
.mu.m in average cell diameter, 0.86 in specific gravity, and 52
degrees in hardness) was obtained. In a buffing machine
(manufactured by AMITEC Corporation), the surface of the sheet was
then buffed subsequently using #120, #240, and #400 sandpaper,
until its thickness reached 2 mm, so that a sheet with regulated
thickness accuracy was obtained. The buffed sheet was stamped into
a piece with a diameter of 61 cm. Concentric circular grooves with
a width 0.25 mm, a pitch of 1.5 mm, and a depth of 0.6 mm were
formed on the surface of the piece using a grooving machine
(manufactured by Techno Corporation), so that a polishing layer was
obtained.
Example 1
[0135] An adhesive layer (50 .mu.m in thickness) was formed on a
support layer made of a urethane foam (NIPPALAY EXT manufactured by
NHK SPRING Co., Ltd.). The adhesive layer was made of a
polyester-based hot-melt adhesive containing 100 parts by weight of
a crystalline polyester resin (VYLON GM420 manufactured by TOYOBO
CO., LTD.) and 5 parts by weight of an o-cresol novolac type epoxy
resin (EOCN 4400 manufactured by Nippon Kayaku Co., Ltd.) having at
least two glycidyl groups per molecule. The surface of the adhesive
layer was heated to 150.degree. C. using an infrared heater so that
the adhesive layer was molten. Subsequently, using a laminator, the
polishing layer prepared in Production Example 1 was laminated and
pressure-bonded onto the molten adhesive layer, and the resulting
laminate was cut into the size of the polishing layer. Using a
laminator, a double-sided pressure-sensitive adhesive tape (442JA
manufactured by 3M Company) was further bonded to the other side of
the support layer, so that a laminated polishing pad was obtained.
The polyester-based hot-melt adhesive had a melting point of
142.degree. C., a specific gravity of 1.22, and a melt flow index
of 21 g/10 minutes.
Example 2
[0136] The same adhesive layer (50 .mu.m in thickness) as in
Example 1 was formed on a 50 .mu.m thick PET film (E5200
manufactured by TOYOBO CO., LTD.) whose both sides had been
corona-treated. The surface of the adhesive layer was heated to
150.degree. C. using an infrared heater so that the adhesive layer
was molten. Subsequently, using a laminator, the polishing layer
prepared in Production Example 1 was laminated and pressure-bonded
onto the molten adhesive layer, and the resulting laminate was cut
into the size of the polishing layer, so that a laminated polishing
layer was obtained.
[0137] The same adhesive layer (50 .mu.m in thickness) as in
Example 1 was formed on a support layer made of a urethane foam
(NIPPALAY EXT manufactured by NHK SPRING Co., Ltd.), and the
surface of the adhesive layer was heated to 150.degree. C. using an
infrared heater, so that the adhesive layer was molten.
Subsequently, using a laminator, the laminated polishing layer was
laminated and pressure-bonded onto the molten adhesive layer, and
the resulting laminate was cut into the size of the laminated
polishing layer. Using a laminator, a double-sided
pressure-sensitive adhesive tape (442JA manufactured by 3M Company)
was further bonded to the other side of the support layer, so that
a laminated polishing pad was obtained.
Example 3
[0138] An opening (56 mm.times.20 mm) was formed through the
polishing layer prepared in Production Example 1 so that a
transparent member could be fit into the opening.
[0139] The same adhesive layer (50 .mu.m in thickness) as in
Example 1 was formed on a 50 .mu.m thick PET film (E5200
manufactured by TOYOBO CO., LTD.) whose both sides had been
corona-treated. The surface of the adhesive layer was heated to
150.degree. C. using an infrared heater so that the adhesive layer
was molten. Subsequently, using a laminator, the polishing layer
was laminated and pressure-bonded onto the molten adhesive layer,
and a transparent member (55 mm.times.19 mm, 1.98 mm in thickness)
was fit into the opening of the polishing layer and pressure-bonded
to the adhesive layer. The resulting laminate was cut into the size
of the polishing layer, so that a laminated polishing layer was
obtained.
[0140] The same adhesive layer (50 .mu.m in thickness) as in
Example 1 was formed on a support layer made of a urethane foam
(NIPPALAY EXT manufactured by NHK SPRING Co., Ltd.), and the
surface of the adhesive layer was heated to 150.degree. C. using an
infrared heater, so that the adhesive layer was molten.
Subsequently, using a laminator, the laminated polishing layer was
laminated and pressure-bonded onto the molten adhesive layer, and
the resulting laminate was cut into the size of the laminated
polishing layer. Using a laminator, a double-sided
pressure-sensitive adhesive tape (442JA manufactured by 3M Company)
was further bonded to the other side of the support layer, and the
support layer and the double-sided pressure-sensitive adhesive tape
located corresponding to the transparent member were shaped into a
size of 50 mm.times.14 mm by punching, so that a laminated
polishing pad was obtained.
Example 4
[0141] A laminated polishing pad was prepared using the same
process as in Example 1, except that a polyester-based hot-melt
adhesive containing 100 parts by weight of a crystalline polyester
resin (VYLON GM420 manufactured by TOYOBO CO., LTD.) and 2 parts by
weight of an o-cresol novolac type epoxy resin (EOCN 4400
manufactured by Nippon Kayaku Co., Ltd.) having at least two
glycidyl groups per molecule was used instead. The polyester-based
hot-melt adhesive had a melting point of 140.degree. C., a specific
gravity of 1.24, and a melt flow index of 26 g/10 minutes.
Example 5
[0142] A laminated polishing pad was prepared using the same
process as in Example 1, except that a polyester-based hot-melt
adhesive containing 100 parts by weight of a crystalline polyester
resin (VYLON GM420 manufactured by TOYOBO CO., LTD.) and 10 parts
by weight of an o-cresol novolac type epoxy resin (EOCN 4400
manufactured by Nippon Kayaku Co., Ltd.) having at least two
glycidyl groups per molecule was used instead. The polyester-based
hot-melt adhesive had a melting point of 145.degree. C., a specific
gravity of 1.19, and a melt flow index of 16 g/10 minutes.
Comparative Example 1
[0143] A laminated polishing pad was prepared using the same
process as in Example 1, except that a polyester-based hot-melt
adhesive containing 100 parts by weight of a crystalline polyester
resin (VYLON GM420 manufactured by TOYOBO CO., LTD.) and 1 parts by
weight of an o-cresol novolac type epoxy resin (EOCN 4400
manufactured by Nippon Kayaku Co., Ltd.) having at least two
glycidyl groups per molecule was used instead. The polyester-based
hot-melt adhesive had a melting point of 139.degree. C., a specific
gravity of 1.25, and a melt flow index of 29 g/10 minutes.
Comparative Example 2
[0144] A laminated polishing pad was prepared using the same
process as in Example 1, except that a polyester-based hot-melt
adhesive containing 100 parts by weight of a crystalline polyester
resin (VYLON GM420 manufactured by TOYOBO CO., LTD.) and 18 parts
by weight of an o-cresol novolac type epoxy resin (EOCN 4400
manufactured by Nippon Kayaku Co., Ltd.) having at least two
glycidyl groups per molecule was used instead. The polyester-based
hot-melt adhesive had a melting point of 147.degree. C., a specific
gravity of 1.18, and a melt flow index of 15 g/10 minutes.
TABLE-US-00001 TABLE 1 Comparative Comparative Example 1 Example 2
Example 3 Example 4 Example 5 Example 1 Example 2 Added amount of
epoxy 5 5 5 2 10 1 18 resin (parts by weight) State of polishing
pad after No lifting No lifting No lifting No lifting No lifting
Lifting Lifting polishing for 60 hours Shearing stress Initial 1070
1102 1150 980 1020 530 230 (N/25 mm square) Material Material
Material Material Material Interfacial Interfacial breaking
breaking breaking breaking breaking peeling peeling After 60 1005
1032 1082 910 970 227 35 (After hours 30 hours) Material Material
Material Material Material Interfacial Interfacial breaking
breaking breaking breaking breaking peeling peeling Polishing rate
Initial 10 12 11 11 11 15 18 uniformity (%) After 60 15 13 12 15 14
43 -- hours
[0145] In each of the laminated polishing pads of Examples 1 to 5,
lifting did not occur even after polishing for 60 hours. Each of
the laminated polishing pads of Examples 1 to 5 also had a high
shearing strength of at least 800 N, and did not underwent
interfacial peeling at the adhesive layer. Each of the laminated
polishing pads of Examples 1 to 5 maintained a polishing rate
uniformity of 20% or less after 60 hours, and showed a stable
polishing rate even after polishing for a long period of time. In
contrast, lifting occurred in the pad of Comparative Example 1
after polishing for 5 hours. The pad of Comparative Example 1 had a
low initial shearing stress, and its shearing stress significantly
decreased after polishing for 60 hours. The pad of Comparative
Example 1 also had a very bad polishing rate uniformity after 60
hours. In the pad of Comparative Example 2, lifting occurred after
polishing for 1 hour. The polishing was aborted after polishing for
3 hours because cracking occurred in the wafer due to the influence
of the lifting in the pad. The pad of Comparative Example 2 also
had a considerably low initial shearing stress, and its shearing
stress significantly decreased after polishing for 3 hours.
Example 6
[0146] A urethane foam composition was applied onto a 50 .mu.m
thick polyethylene naphthalate (PEN) film (Teonex Q83 manufactured
by Teijin DuPont Films Japan Limited, 0% in rate of dimensional
change) and cured to form a cushion layer (0.5 in specific gravity,
50 degrees in Asker C hardness, 800 .mu.m in thickness). The same
adhesive layer (50 .mu.m in thickness) as in Example 1 was formed
on the cushion layer, and the surface of the adhesive layer was
heated to 150.degree. C. using an infrared heater, so that the
adhesive layer was molten. Subsequently, using a laminator, the
polishing layer prepared in Production Example 1 was laminated and
pressure-bonded onto the molten adhesive layer, and the resulting
laminate was cut into the size of the polishing layer. Using a
laminator, a double-sided pressure-sensitive adhesive tape (442JA
manufactured by 3M Company) was further bonded to the other side of
the PEN film, so that a laminated polishing pad was obtained.
Example 7
[0147] A laminated polishing pad was prepared using the same
process as in Example 6, except that a 38 .mu.m thick PEN film
(Teonex Q81 manufactured by Teijin DuPont Films Japan Limited, 0.2%
in rate of dimensional change) was used instead.
Example 8
[0148] A laminated polishing pad was prepared using the same
process as in Example 6, except that a 50 .mu.m thick PET film
having undergone thermal shrinkage treatment (Tetoron SL
manufactured by Teijin DuPont Films Japan Limited, 0.4% in rate of
dimensional change) was used instead.
Example 9
[0149] A laminated polishing pad was prepared using the same
process as in Example 6, except that a 50 .mu.m thick PEN film
(Teonex Q51 manufactured by Teijin DuPont Films Japan Limited, 0.6.
% in rate of dimensional change) was used instead.
Example 10
[0150] A laminated polishing pad was prepared using the same
process as in Example 6, except that a 16 .mu.m thick PEN film
(Teonex Q51 manufactured by Teijin DuPont Films Japan Limited, 1.0%
in rate of dimensional change) was used instead.
Example 11
[0151] A laminated polishing pad was prepared using the same
process as in Example 6, except that a 50 .mu.m thick polyimide
film (AURUM FILM PL450C manufactured by Mitsui Chemicals, Inc, 0%
in rate of dimensional change) was used instead.
Comparative Example 3
[0152] A laminated polishing pad was prepared using the same
process as in Example 6, except that a 50 .mu.m thick PET film
(Tetoron G2 manufactured by Teijin DuPont Films Japan Limited, 1.7%
in rate of dimensional change) was used instead.
TABLE-US-00002 TABLE 2 Comparative Example 6 Example 7 Example 8
Example 9 Example 10 Example 11 Example 3 Rate (%) of 0 0.2 0.4 0.6
1.0 0 1.7 dimensional change of resin film Warpage (mm) of pad 0 2
4 5 8 0 18 Polishing rate Initial 8 9 11 13 17 7 25 uniformity
(%)
Production Example 2
[0153] (Preparation of Transparent Member)
[0154] A mixture of 128 parts by weight of polyester polyol (2,400
in number average molecular weight) obtained by polymerization of
adipic acid, hexanediol, and ethylene glycol, and 30 parts by
weight of 1,4-butanediol was prepared. The temperature of the
resulting first liquid mixture was adjusted to 70.degree. C. To the
first liquid mixture was added 100 parts by weight of
4,4'-diphenylmethane diisocyanate, whose temperature had been
adjusted to 70.degree. C. in advance, and stirred for 1 minute to
form a second liquid mixture. The second liquid mixture was poured
into a vessel kept at 100.degree. C., and subjected to post-curing
at 100.degree. C. for 8 hours, so that a polyurethane resin was
obtained. The resulting polyurethane resin was injection molded
into a transparent member (56 mm.times.20 mm, 2.75 mm in
thickness).
Production Example 3
[0155] (Preparation of Polyurethane Resin Foam Sheet)
[0156] To a vessel were added 100 parts by weight of a
polyether-based prepolymer (ADIPRENE L-325 manufactured by Uniroyal
Chemical Company, NCO concentration: 2.22 meq/g) and 3 parts by
weight of a silicone surfactant (SH-192 manufactured by Dow Corning
Toray Silicone Co., Ltd.) and mixed. The mixture was adjusted to
80.degree. C. and degassed under reduced pressure. Subsequently,
the mixture was vigorously stirred with a stirring blade at a
rotational speed of 900 rpm for about 4 minutes in such a manner
that air bubbles were incorporated into the reaction system. To the
resulting mixture was added 26 parts by weight of MOCA (CUAMINE-MT
manufactured by IHARA CHEMICAL INDUSTRY CO., LTD.) whose
temperature had been adjusted to 120.degree. C. in advance. The
liquid mixture was stirred for about 1 minute and then poured into
a pan-shaped open mold (casting vessel). At the point when the
liquid mixture lost its fluidity, it was placed in an oven, and
subjected to post-curing at 100.degree. C. for 16 hours, so that a
polyurethane resin foam block was obtained. The polyurethane resin
foam block was sliced using a slicer (manufactured by Fecken-Kirfel
GbmH), so that a polyurethane resin foam sheet was obtained (0.86
in specific gravity, 52 degrees in D hardness).
Example 12
[0157] The surface of the polyurethane resin foam sheet prepared in
Production Example 3 was buffed using a buffing machine
(manufactured by AMITEC Corporation) so that its thickness accuracy
was controlled. After the buffing, the polyurethane resin foam
sheet had a thickness of 2 mm and an arithmetic mean roughness (Ra)
of non-polishing surface of 7 .mu.m. Concentric circular grooves
with a width 0.4 mm, a pitch of 3.1 mm, and a depth of 0.76 mm were
formed on the polishing-side surface of the sheet using a grooving
machine (manufactured by TOHO KOKI CO., LTD.). A piece with a
diameter of 77 cm was then punched from the resulting sheet, so
that a polishing layer was obtained. The arithmetic mean roughness
(Ra) of the non-polishing surface was measured according to JIS B
0601-1994.
[0158] An adhesive layer (50 .mu.m in thickness) was formed on a
support layer made of a urethane foam (NIPPALAY EXT manufactured by
NHK SPRING Co., Ltd., 0.8 mm in thickness). The adhesive layer was
made of a polyester-based hot-melt adhesive containing 100 parts by
weight of a crystalline polyester resin (VYLON GM420 manufactured
by TOYOBO CO., LTD.) and 5 parts by weight of an o-cresol novolac
type epoxy resin (EOCN 4400 manufactured by Nippon Kayaku Co.,
Ltd.) having at least two glycidyl groups per molecule. The surface
of the adhesive layer was heated to 150.degree. C. using an
infrared heater so that the adhesive layer was molten.
Subsequently, using a laminator, the resulting polishing layer was
laminated and pressure-bonded onto the molten adhesive layer, and
the hot-melt adhesive was cured, so that a laminated polishing
sheet was obtained. The laminated polishing sheet was then cut into
the size of the polishing layer. A through hole (56 mm.times.20 mm)
was formed in the resulting circular laminated polishing sheet so
as to be located 12 cm from the center of the sheet. Subsequently,
using a laminator, a double-sided pressure-sensitive adhesive tape
(442JA manufactured by 3M Company) was bonded to the other side of
the support layer. The transparent member prepared in Production
Example 2 was inserted into the through hole and bonded to the
double-sided pressure-sensitive adhesive tape, so that a laminated
polishing pad was obtained.
Example 13
[0159] A laminated polishing pad was prepared using the same
process as in Example 12, except that the thickness of the adhesive
layer made of the polyester-based hot-melt adhesive was changed to
25 .mu.m.
Example 14
[0160] A laminated polishing pad was prepared using the same
process as in Example 12, except that the arithmetic mean roughness
(Ra) of the non-polishing surface was changed to 3 .mu.m and the
thickness of the adhesive layer made of the polyester-based
hot-melt adhesive was changed to 25 .mu.m.
Example 15
[0161] A laminated polishing pad was prepared using the same
process as in Example 12, except that the arithmetic mean roughness
(Ra) of the non-polishing surface was changed to 12 .mu.m and the
thickness of the adhesive layer made of the polyester-based
hot-melt adhesive was changed to 25 .mu.m.
Example 16
[0162] A laminated polishing pad was prepared using the same
process as in Example 12, except that the thickness of the adhesive
layer made of the polyester-based hot-melt adhesive was changed to
125 .mu.m.
Example 17
[0163] A laminated polishing pad was prepared using the same
process as in Example 12, except that the thickness of the adhesive
layer made of the polyester-based hot-melt adhesive was changed to
200 .mu.m.
Example 18
[0164] A laminated polishing pad was prepared using the same
process as in Example 12, except that the arithmetic mean roughness
(Ra) of the non-polishing surface was changed to 3 .mu.m and the
thickness of the adhesive layer made of the polyester-based
hot-melt adhesive was changed to 200 .mu.m.
Example 19
[0165] A laminated polishing pad was prepared using the same
process as in Example 12, except that the arithmetic mean roughness
(Ra) of the non-polishing surface was changed to 12 .mu.m and the
thickness of the adhesive layer made of the polyester-based
hot-melt adhesive was changed to 200 .mu.m.
Comparative Example 4
[0166] A laminated polishing pad was prepared using the same
process as in Example 12, except that the arithmetic mean roughness
(Ra) of the non-polishing surface was changed to 0.5 .mu.m.
Comparative Example 5
[0167] A laminated polishing pad was prepared using the same
process as in Example 12, except that the arithmetic mean roughness
(Ra) of the non-polishing surface was changed to 16 .mu.m.
Comparative Example 6
[0168] A laminated polishing pad was prepared using the same
process as in Example 12, except that the thickness of the adhesive
layer made of the polyester-based hot-melt adhesive was changed to
225 .mu.m.
Comparative Example 7
[0169] A laminated polishing pad was prepared using the same
process as in Example 12, except that a double-sided
pressure-sensitive adhesive tape (#5782W manufactured by SEKISUI
CHEMICAL CO., LTD., 130 .mu.m in thickness) was used instead of the
adhesive layer made of the polyester-based hot-melt adhesive.
TABLE-US-00003 TABLE 3 Example Example Example Example Example
Example Example 12 13 14 15 16 17 18 Adhesive layer 50 25 25 25 125
200 200 thickness (.mu.m) Ra (.mu.m) 7 7 3 12 7 7 3 Shearing 290
270 260 280 300 255 260 stress Material Material Material Material
Material Material Material (N/25 mm breaking breaking breaking
breaking breaking breaking breaking square) at 80.degree. C.
Example Comparative Comparative Comparative Comparative 19 Example
4 Example 5 Example 6 Example 7 Adhesive layer 200 50 50 225 --
thickness (.mu.m) Ra (.mu.m) 12 0.5 16 7 7 Shearing 270 180 190 160
150 stress Material Material Material Material Interfacial (N/25 mm
breaking breaking + breaking + breaking + peeling square) partial
partial partial at 80.degree. C. interfacial interfacial
interfacial peeling peeling peeling
INDUSTRIAL APPLICABILITY
[0170] A laminated polishing pad of the invention is capable of
performing planarization materials requiring a high surface
planarity such as optical materials including a lens and a
reflective mirror, a silicon wafer, a glass substrate or an
aluminum substrate for a hard disk and a product of general metal
polishing with stability and a high polishing efficiency. A
laminated polishing pad of the invention is preferably employed,
especially, in a planarization step of a silicon wafer or a device
on which an oxide layer or a metal layer has been formed prior to
further stacking an oxide layer or a metal layer thereon.
DESCRIPTION OF REFERENCE SIGNS
[0171] In the drawings, reference numeral 1 represents a laminated
polishing pad, 2 a polishing platen, 3 a polishing agent (slurry),
4 an object to be polished (semiconductor wafer), 5 a support
(polishing head), 6 and 7 each a rotating shaft, 8 a polishing
layer, 9 a transparent member, 10 and 13 an opening, 11 an adhesive
member, 12 a support layer, 14 a double-sided adhesive sheet, 15 a
through hole.
* * * * *