U.S. patent application number 11/594988 was filed with the patent office on 2007-08-02 for polishing slurry for silicon oxide, additive liquid and polishing method.
This patent application is currently assigned to HITACHI CHEMICAL CO., LTD.. Invention is credited to Toshiaki Akutsu, Toranosuke Ashizawa, Kazuhiro Enomoto, Masato Fukasawa, Masaya Nishiyama, Yuuto Otsuki.
Application Number | 20070175104 11/594988 |
Document ID | / |
Family ID | 38023279 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070175104 |
Kind Code |
A1 |
Nishiyama; Masaya ; et
al. |
August 2, 2007 |
Polishing slurry for silicon oxide, additive liquid and polishing
method
Abstract
The polishing slurry of the invention is a polishing slurry for
polishing a silicon oxide film on polysilicon, which contains an
abrasive, polysilicon polishing inhibitor, and water. As the
polishing inhibitor, it is preferable to use (1) a water-soluble
polymer having a N-monosubstituted or N,N-disubstituted skeleton
substituted by any member selected from the group consisting of
acrylamide, methacrylamide, and .alpha.-substituted derivatives
thereof, (2) polyethylene glycol, (3) an oxyethylene adduct of an
acetylene-based diol, (4) a water-soluble organic compound having
an acetylene bond, (5) an alkoxylated linear aliphatic alcohol, or
(6) a copolymer containing polyvinyl pyrrolidone or vinyl
pyrrolidone. There is provided a polishing method which is capable
of polishing a silicon oxide film on a polysilicon film at a high
speed, and inhibiting the progress of polishing of a polysilicon
film in exposed parts in the manufacturing method for a
semiconductor.
Inventors: |
Nishiyama; Masaya;
(Hitachi-shi, JP) ; Enomoto; Kazuhiro; (Mito-shi,
JP) ; Fukasawa; Masato; (Hitachi-shi, JP) ;
Akutsu; Toshiaki; (Tokai-shi, JP) ; Otsuki;
Yuuto; (Hitachi-shi, JP) ; Ashizawa; Toranosuke;
(Hitachi-shi, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW
SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
HITACHI CHEMICAL CO., LTD.
Tokyo
JP
|
Family ID: |
38023279 |
Appl. No.: |
11/594988 |
Filed: |
November 9, 2006 |
Current U.S.
Class: |
51/307 ;
257/E21.244; 51/298; 51/308; 51/309 |
Current CPC
Class: |
H01L 21/31053 20130101;
C09K 3/1463 20130101; C09K 3/1409 20130101; C09G 1/02 20130101 |
Class at
Publication: |
051/307 ;
051/298; 051/308; 051/309 |
International
Class: |
B24D 3/02 20060101
B24D003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 11, 2005 |
JP |
2005-327422 |
Claims
1. A polishing slurry for silicon oxide for polishing a silicon
oxide film on polysilicon, which contains an abrasive, a
polysilicon polishing inhibitor, and water.
2. The polishing slurry for silicon oxide according to claim 1,
wherein the ratio of the polishing rate for silicon oxide to that
for polysilicon is 10 or more.
3. The polishing slurry for silicon oxide according to claim 1 or
2, wherein the polysilicon polishing inhibitor is a water-soluble
polymer having a N-monosubstituted or N,N-disubstituted skeleton
substituted by any member selected from the group consisting of
acrylamide, methacrylamide, and .alpha.-substituted derivatives
thereof.
4. The polishing slurry for silicon oxide according to claim 3,
wherein the water-soluble polymer is a polymer or copolymer
containing at least one selected from the group consisting of a
polymerizable monomer represented by the following general formula
(I) and a polymerizable monomer represented by the following
general formula (II). ##STR9## (In the general formula (I), R.sub.1
represents a hydrogen atom, methyl group, phenyl group, benzyl
group, chloro group, difluoromethyl group, trifluoromethyl group,
or cyano group, and R.sub.2 and R.sub.3 each independently
represents a hydrogen atom, alkyl chain of C.sub.1 to C.sub.18,
methylol group, or acetyl group with the proviso that the case
where both of them simultaneously represent a hydrogen atom is
excluded.) ##STR10## (In the general formula (II), R.sub.1
represents a hydrogen atom, methyl group, phenyl group, benzyl
group, chloro group, difluoromethyl group, trifluoromethyl group,
or cyano group, R.sub.4 represents a morpholino group,
thiomorpholino group, pyrrolidino group, or piperidino group.)
5. The polishing slurry for silicon oxide according to claim 1 or
2, wherein the polysilicon polishing inhibitor is polyethylene
glycol.
6. The polishing slurry for silicon oxide according to claim 1 or
2, wherein the polysilicon polishing inhibitor is an oxyethylene
adduct of a acetylene-based diol.
7. The polishing slurry for silicon oxide according to claim 1 or
2, wherein the polysilicon polishing inhibitor is at least either
of the compound represented by the following general formula (III)
and the compound and represented by the following general formula
(IV). [Formula 3] R.sup.1--C.ident.C--R.sup.2 (III) (In the general
formula (III), R.sup.1 represents a hydrogen atom or substituted or
unsubstituted alkyl group having 1 to 5 carbon atoms, R.sup.2
represents a substituted or unsubstituted alkyl group having 4 to
10 carbon atoms.) ##STR11## (In the general formula (IV), R.sup.3
to R.sup.6 each independently represent a hydrogen atom or
substituted or unsubstituted alkyl group having 1 to 5 carbon
atoms, R.sup.7 and R.sup.8 each independently represent a
substituted or unsubstituted alkylene group having 1 to 5 carbon
atoms, and m and n each independently represents 0 or a positive
number.)
8. The polishing slurry for silicon oxide according to claim 1 or
2, wherein the polysilicon polishing inhibitor is an alkoxylated
linear aliphatic alcohol.
9. The polishing slurry for silicon oxide according to any of
claims 1 or 2, which contains two or more types of the polysilicon
polishing inhibitor.
10. The polishing slurry for silicon oxide according to claim 9,
wherein the polysilicon polishing inhibitor includes two or more
compounds selected from a water-soluble polymer having a
N-monosubstituted or N,N-disubstituted skeleton substituted by any
member selected from the group consisiting of acrylamide,
methacrylamide, and .alpha.-substituted derivatives thereof,
polyethylene glycol, an oxyethylene adduct of an acetylene-based
diol, a compound represented by the following general formula
(III), a compound represented by the following general formula
(IV), and an alkoxylated linear aliphatic alcohol. [Formula 9]
R.sup.1--C.ident.C--R.sup.2 (III) (In the general formula (III),
R.sup.1 represents a hydrogen atom or substituted or unsubstituted
alkyl group having 1 to 5 carbon atoms, R.sup.2 represents a
substituted or unsubstituted alkyl group having 4 to 10 carbon
atoms.) ##STR12## (In the general formula (IV), R.sup.3 to R.sup.6
each independently represent a hydrogen atom or substituted or
unsubstituted alkyl group having 1 to 5 carbon atoms, R.sup.7 and
R.sup.8 each independently represent a substituted or unsubstituted
alkylene group having 1 to 5 carbon atoms, and m and n each
independently represents 0 or a positive number.)
11. The polishing slurry for silicon oxide according to claim 3,
wherein the content of the polysilicon polishing inhibitor is
0.005% by mass or more and 2% by mass or less.
12. The polishing slurry for silicon oxide according to claim 3,
wherein the pH is 5.0 to 8.0.
13. The polishing slurry for silicon oxide according to any of
claims 1 or 2, which contains at least one selected from
polyacrylic acid, polyacrylate, and a copolymer containing
acrylate.
14. The polishing slurry for silicon oxide according to any of
claims 1 or 2, wherein the abrasive contains cerium oxide.
15. The polishing slurry for silicon oxide according to claim 1 or
2, wherein the polysilicon polishing inhibitor contains polyvinyl
pyrrolidone or a copolymer containing vinyl pyrrolidone.
16. The polishing slurry for silicon oxide according to claim 15,
wherein the content of the polysilicon polishing inhibitor is 0.005
to 5% by mass.
17. The polishing slurry for silicon oxide according to claim 15,
wherein the pH is 5.0 to 12.0.
18. The polishing slurry for silicon oxide according to claim 15,
which contains at least one selected from polyacrylic acid,
polyacrylate, or a copolymer containing acrylate.
19. The polishing slurry for silicon oxide according to claim 15,
wherein the abrasive contains cerium oxide.
20. The polishing slurry for silicon oxide according to claim 13,
wherein the content of at least one selected from polyacrylic acid,
polyacrylate, and a copolymer containing acrylate is 0.01 to 5% by
mass.
21. The polishing slurry for silicon oxide according to any of
claims 1 or 2, wherein the abrasive contains silicon oxide.
22. A method for polishing a semiconductor substrate using the
polishing slurry for silicon oxide according to claim 1.
23. An additive liquid for polishing slurry used in a polishing
slurry for polishing a silicon oxide film on polysilicon, which
contains a polysilicon polishing inhibitor and water.
24. The additive liquid for polishing slurry according to claim 23,
wherein the polysilicon polishing inhibitor is a water-soluble
polymer having a N-monosubstituted or N,N-disubstituted skeleton
substituted by any member selected from the group consisting of
acrylamide, methacrylamide, and .alpha.-substituted derivatives
thereof.
25. The additive liquid for polishing slurry according to claim 24,
wherein the water-soluble polymer is a polymer or copolymer
containing at least one selected from the group consisting of a
polymerizable monomer represented by the following general formula
(I) and a polymerizable monomer represented by the following
general formula (II). ##STR13## (In the general formula (I),
R.sub.1 represents a hydrogen atom, methyl group, phenyl group,
benzyl group, chloro group, difluoromethyl group, trifluoromethyl
group, or cyano group, and R.sub.2 and R.sub.3 each independently
represents a hydrogen atom, alkyl chain of C.sub.1 to C.sub.18,
methylol group, or acetyl group with the proviso that the case
where both of them simultaneously represent a hydrogen atom is
excluded.) ##STR14## (In the general formula (II), R.sub.1
represents a hydrogen atom, methyl group, phenyl group, benzyl
group, chloro group, difluoromethyl group, trifluoromethyl group,
or cyano group, R.sub.4 represents a morpholino group,
thiomorpholino group, pyrrolidino group, or piperidino group.)
26. The additive liquid for polishing slurry according to claim 23,
wherein the polysilicon polishing inhibitor is polyethylene
glycol.
27. The additive liquid for polishing slurry according to claim 23,
wherein the polysilicon polishing inhibitor is an oxyethylene
adduct of an acetylene-based diol.
28. The additive liquid for polishing slurry according to claim 23,
wherein the polysilicon polishing inhibitor is at least either of
the compound represented by the following general formula (III) and
the compound and represented by the following general formula (IV).
[Formula 7] R.sup.1--C.ident.C--R.sup.2 (III) (In the general
formula (III), R.sup.1 represents a hydrogen atom or substituted or
unsubstituted alkyl group having 1 to 5 carbon atoms, R.sup.2
represents a substituted or unsubstituted alkyl group having 4 to
10 carbon atoms.) ##STR15## (In the general formula (IV), R.sup.3
to R.sup.6 each independently represent a hydrogen atom or
substituted or unsubstituted alkyl group having 1 to 5 carbon
atoms, R.sup.7 and R.sup.8 each independently represent a
substituted or unsubstituted alkylene group having 1 to 5 carbon
atoms, and m and n each independently represents 0 or a positive
number.)
29. The additive liquid for polishing slurry according to claim 23,
wherein the polysilicon polishing inhibitor is an alkoxylated
linear aliphatic alcohol.
30. The additive liquid for polishing slurry according to any of
claims 23 through 29, which contains two or more types of the
polysilicon polishing inhibitor.
31. The additive liquid for polishing slurry according to claim 30,
wherein the polysilicon polishing inhibitor includes two or more
compounds selected from a water-soluble polymer having a
N-monosubstituted or N,N-disubstituted skeleton substituted bv any
member selected from the group, consisting of acrylamide,
methacrylamide, and .alpha.-substituted derivatives thereof,
polyethylene glycol, an oxyethylene adduct of an acetylene-based
diol, a compound represented by the following general formula
(III), a compound represented by the following general formula
(IV), and an alkoxylated linear aliphatic alcohol. [Formula 11]
R.sup.1--C.ident.C--R.sup.2 (III) (In the general formula (III),
R.sup.1 represents a hydrogen atom or substituted or unsubstituted
alkyl group having 1 to 5 carbon atoms R.sup.2 represents a
substituted or unsubstituted alkyl group having 4 to 10 carbon
atoms.) ##STR16## (In the general formula (IV), R.sup.3 to R.sup.6
each independently represent a hydrogen atom or substituted or
unsubstituted alkyl group having 1 to 5 carbon atoms, R.sup.7 and
R.sup.8 each independently represent a substituted or unsubstituted
alkylene group having 1 to 5 carbon atoms, and m and n each
independently represents 0 or a positive number.)
32. The additive liquid for polishing slurry according to any of
claims 23 through 29, which further contains at least one selected
from polyacrylic acid, polyacrylate, and a copolymer containing
acrylate.
33. A polishing method using the polishing slurry for silicon oxide
according to claim 1, wherein the object to be polished is held
against a polishing pad with the surface thereof to be polished
facing the polishing pad, and polished by being slid relative to
the polishing pad while the polishing slurry is supplied between
the polishing pad and the surface to be polished.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a polishing slurry preferably used
in the planarization process for dielectrics on substrate surfaces,
which is a manufacturing technique for semiconductor devices, and
particularly relates to a polishing slurry for silicon oxide on
polysilicon, an additive liquid used in the polishing slurry, and a
polishing method using the polishing slurry.
[0003] 2. Description of the Related Art
[0004] In the present ULSI semiconductor device manufacturing
processes, processing techniques for achieving higher density and
fineness have been developed. Among them, CMP (Chemical Mechanical
Polishing) technique is becoming an essential technique in the
manufacturing process for semiconductor devices, for planarization
of interlayer dielectrics, shallow trench isolation, formation of
plugs or buried metal wiring, and other purposes.
[0005] In the manufacturing process for semiconductor devices, as
chemical mechanical polishing slurries for the planarization of
inorganic dielectric layers, a fumed silica polishing slurry,
colloidal silica polishing slurry, and cerium oxide polishing
slurry have been generally studied. Examples of inorganic
dielectric layers include a silicon oxide dielectric formed by a
plasma-CVD method, a low-pressure-CVD method, or other method.
Fumed silica is produced from silicon tetrachloride by heat
decomposition or other method, and the particles are grown to be
used as an abrasive in a polishing slurry. Colloidal silica used to
be made from water glass, but alkali components derived from water
glass remains in colloidal silica, thus it contains too much metal
impurities for semiconductor applications. Afterward, a method for
manufacturing colloidal silica from alkoxide was established, which
has allowed the manufacture of high purity products, and
commercialization of colloidal silica which can be used as an
abrasive for semiconductors. In order to use such a silica
polishing slurry for polishing silicon oxide for a semiconductor,
such as silicon oxide or borosilicate, the pH of the slurry is
often adjusted to alkaline for increasing the polishing rate.
[0006] On the other hand, cerium oxide particles have lower
hardness and are less prone to give scratches on the polishing
surface in comparison with silica particles or alumina particles.
Further, since cerium oxide polishes silicon oxide at a high
polishing rate, the applicable pH range is not particularly
limited. In recent years, a CMP polishing slurry using a high
purity cerium oxide abrasive is used for semiconductor
applications. The technique is, for example, disclosed in Japanese
Patent Application Laid-Open No. 10-106994. Another known technique
is to add an additive to a cerium oxide polishing slurry for
controlling the polishing rate thereof to increase global flatness.
The technique is disclosed, for example, in Japanese Patent
Application Laid-Open No. 8-22970.
[0007] Along with the progress of semiconductor device structures,
CMP processes are diversified. After the generation of design rule
0.25 .mu.m, shallow trench isolation is used for isolating devices
in an integrated circuit. In shallow trench isolation, CMP is used
for removing the surplus parts of a silicon oxide film formed on
the substrate. In order to stop polishing by CMP, a stopper film
which is polished at a low rate is formed under the silicon oxide
film. The stopper film is typically made of silicon nitride, and
the polishing rate ratio between the silicon oxide film and the
stopper film is preferably large. Such a technique of using a
stopper for stopping polishing is used in other applications as
well as shallow trench isolation. Besides shallow trench isolation,
a stopper may be used, for example, in formation of a plug or the
like wherein the surplus parts of a film must be removed by CMP for
planarization.
SUMMARY OF THE INVENTION
[0008] Silicon nitride has been commercialized as a stopper for
shallow trench isolation because it has high hardness and is
readily controllable in polishing rate. Stoppers other than silicon
nitride may be possible as long as they are films controllable in
their polishing rate. For example, a barrier metal for Cu wiring
also serves as a stopper in CMP. In addition, polysilicon
(polycrystalline silicon) will be usable as a stopper if the
polishing rate thereof is sufficiently controllable.
[0009] Polysilicon, which is used as a conductive material for a
transistor gate or the like, can be used in different applications
from silicon nitride if a CMP technique for using polysilicon as a
stopper is established. However, it has been difficult to control
polysilicon to a degree where it can be used as a stopper, or to
achieve a sufficiently large polishing rate ratio between a film to
be polished and polysilicon either with a silica polishing slurry
or a cerium oxide polishing slurry.
[0010] The object of the invention is to provide a polishing slurry
for silicon oxide on polysilicon which achieves a sufficiently
large polishing rate ratio between silicon oxide and polysilicon
for making polysilicon applicable as a stopper, and a polishing
method using the same for polishing a semiconductor substrate or
the like.
[0011] The invention relates to [1] a polishing slurry for silicon
oxide for polishing a silicon oxide film on polysilicon, which
contains an abrasive, a polysilicon polishing inhibitor, and
water.
[0012] Further, the invention relates to [2] the polishing slurry
for silicon oxide according to [1], wherein the ratio of the
polishing rate for silicon oxide to that for polysilicon is 10 or
more.
[0013] Further, the invention relates to [3] the polishing slurry
for silicon oxide according to [1] or [2], wherein the polysilicon
polishing inhibitor is a water-soluble polymer having a
N-monosubstituted or N,N-disubstituted skeleton substituted by any
member selected from the group consisting of acrylamide,
methacrylamide, and .alpha.-substituted derivatives thereof.
[0014] Further, the invention relates to [4] the polishing slurry
for silicon oxide according to [3], wherein the water-soluble
polymer is a polymer or copolymer containing at least one selected
from the group consisting of a polymerizable monomer represented by
the following formula (I) and a polymerizable monomer represented
by the following general formula (II). ##STR1##
[0015] (In the general formula (I), R.sub.1 represents a hydrogen
atom, methyl group, phenyl group, benzyl group, chloro group,
difluoromethyl group, trifluoromethyl group, or cyano group, and
R.sub.2 and R.sub.3 each independently represents a hydrogen atom,
alkyl chain of C.sub.1 to C.sub.18, methylol group, or acetyl group
with the proviso that the case where both of them simultaneously
represent a hydrogen atom is excluded.) ##STR2##
[0016] (In the general formula (II), R.sub.1 represents a hydrogen
atom, methyl group, phenyl group, benzyl group, chloro group,
difluoromethyl group, trifluoromethyl group, or cyano group,
R.sub.4 represents a morpholino group, thiomorpholino group,
pyrrolidino group, or piperidino group.)
[0017] Further, the invention relates to [5] the polishing slurry
for silicon oxide according to [1] or [2], wherein the polysilicon
polishing inhibitor is polyethylene glycol.
[0018] Further, the invention relates to [6] the polishing slurry
for silicon oxide according to [1] or [2], wherein the polysilicon
polishing inhibitor is an oxyethylene adduct of a acetylene-based
diol.
[0019] Further, the invention relates to [7] the polishing slurry
for silicon oxide according to [1] or [2], wherein the polysilicon
polishing inhibitor is at least either of the compound represented
by the following general formula (III) and the compound and
represented by the following general formula (IV).
[0020] [Formula 3] R.sup.1--C.ident.C--R.sup.2 (III)
[0021] (In the general formula (III), R.sup.1 represents a hydrogen
atom or substituted or unsubstituted alkyl group having 1 to 5
carbon atoms, R.sup.2 represents a substituted or unsubstituted
alkyl group having 4 to 10 carbon atoms.) ##STR3## (In the general
formula (IV), R.sup.3to R.sup.6 each independently represent a
hydrogen atom or substituted or unsubstituted alkyl group having 1
to 5 carbon atoms, R.sup.7 and R.sup.8 each independently represent
a substituted or unsubstituted alkylene group having 1 to 5 carbon
atoms, and m and n each independently represents 0 or a positive
number.)
[0022] Further, the invention relates to [8] the polishing slurry
for silicon oxide according to [1] or [2], wherein the polysilicon
polishing inhibitor is an alkoxylated linear aliphatic alcohol.
[0023] Further, the invention relates to [9] the polishing slurry
for silicon oxide according to any of [1] through [7], which
contains two or more types of the polysilicon polishing
inhibitor.
[0024] Further, the invention relates to [10] the polishing slurry
for silicon oxide according to [9], wherein the polysilicon
polishing inhibitor includes two or more compounds selected from
the [0025] water-soluble polymer, [0026] polyethylene glycol,
[0027] an oxyethylene adduct of an acetylene-based diol, [0028] a
compound represented by the general formula (III), [0029] a
compound represented by the general formula (IV), and [0030] an
alkoxylated linear aliphatic alcohol.
[0031] Further, the invention relates to [11] the polishing slurry
for silicon oxide according to any of [3] through [10], wherein the
content of the polysilicon polishing inhibitor is 0.005% by mass or
more and 2% by mass or less.
Further, the invention relates to [12] the polishing slurry for
silicon oxide according to any of [3] through [11], wherein the pH
is 5.0 to 8.0.
[0032] Further, the invention relates to [13] the polishing slurry
for silicon oxide according to any of [1] through [12], which
contains at least one selected from polyacrylic acid, polyacrylate,
and a copolymer containing acrylate.
[0033] Further, the invention relates to [14] the polishing slurry
for silicon oxide according to any of [1] through [13], wherein the
abrasive contains cerium oxide.
[0034] Further, the invention relates to [15] the polishing slurry
for silicon oxide according to [1] or [2], wherein the polysilicon
polishing inhibitor contains polyvinyl pyrrolidone or a copolymer
containing vinyl pyrrolidone.
[0035] Further, the invention relates to [16] the polishing slurry
for silicon oxide according to [15], wherein the content of the
polysilicon polishing inhibitor is 0.005 to 5% by mass.
[0036] Further, the invention relates to [17] the polishing slurry
for silicon oxide according to [15] or [16], wherein the pH is 5.0
to 12.0.
[0037] Further, the invention relates to [18] the polishing slurry
for silicon oxide according to any of [15] through [17], which
contains at least one selected from polyacrylic acid, polyacrylate,
and a copolymer containing acrylate.
[0038] Further, the invention relates to [19] the polishing slurry
for silicon oxide according to any of [15] through [18], wherein
the abrasive contains cerium oxide.
[0039] Further, the invention relates to [20] the polishing slurry
for silicon oxide according to any of [1] through [19], wherein the
content of at least one selected from polyacrylic acid,
polyacrylate, and a copolymer containing acrylate is 0.01 to 5% by
mass.
[0040] Further, the invention relates to [21] the polishing slurry
for silicon oxide according to any of [1] through [20], wherein the
abrasive contains silicon oxide.
Further, the invention relates to [22] a method for polishing a
semiconductor substrate using the polishing slurry for silicon
oxide according to any of [1] through [21].
Further, the invention relates to [23] an additive liquid for
polishing slurry used in a polishing slurry for polishing a silicon
oxide film on polysilicon, which contains a polysilicon polishing
inhibitor and water.
[0041] Further, the invention relates to [24] the additive liquid
for polishing slurry according to [23], wherein the polysilicon
polishing inhibitor is a water-soluble polymer having a
N-monosubstituted or N,N-disubstituted skeleton substituted by any
member selected from the group consisting of acrylamide,
methacrylamide, and .alpha.-substituted derivatives thereof.
Further, the invention relates to [25] the additive liquid for
polishing slurry according to [24], wherein the water-soluble
polymer is a polymer or copolymer containing at least one selected
from the group consisting of a polymerizable monomer represented by
the following formula (I) and apolymerizable monomer represented by
the following general formula (II). ##STR4##
[0042] (In the general formula (I), R.sub.1 represents a hydrogen
atom, methyl group, phenyl group, benzyl group, chloro group,
difluoromethyl group, trifluoromethyl group, or cyano group, and
R.sub.2 and R.sub.3 each independently represents a hydrogen atom,
alkyl chain of C.sub.1 to C.sub.18, methylol group, or acetyl group
with the proviso that the case where both of them simultaneously
represent a hydrogen atom is excluded.) ##STR5##
[0043] (In the general formula (II), R.sub.1 represents a hydrogen
atom, methyl group, phenyl group, benzyl group, chloro group,
difluoromethyl group, trifluoromethyl group, or cyano group,
R.sub.4 represents a morpholino group, thiomorpholino group,
pyrrolidino group, or piperidino group.)
[0044] Further, the invention relates to [26] the additive liquid
for polishing slurry according to [23], wherein the polysilicon
polishing inhibitor is polyethylene glycol.
[0045] Further, the invention relates to [27] the additive liquid
for polishing slurry according to [23], wherein the polysilicon
polishing inhibitor is an oxyethylene adduct of an acetylene-based
diol.
[0046] Further, the invention relates to [28] the additive liquid
for polishing slurry according to [23], wherein the polysilicon
polishing inhibitor is at least either of the compound represented
by the following general formula (III) and the compound and
represented by the following general formula (IV).
[0047] [Formula 7] R.sup.1--C.ident.C--R.sup.2 (III)
[0048] (In the general formula (III), R.sup.1 represents a hydrogen
atom or substituted or unsubstituted alkyl group having 1 to 5
carbon atoms, R.sup.2 represents a substituted or unsubstituted
alkyl group having 4 to 10 carbon atoms.) ##STR6##
[0049] (In the general formula (IV), R.sup.3 to R.sup.6 each
independently represent a hydrogen atom or substituted or
unsubstituted alkyl group having 1 to 5 carbon atoms, R.sup.7 and
R.sup.8 each independently represent a substituted or unsubstituted
alkylene group having 1 to 5 carbon atoms, and m and n each
independently represents 0 or a positive number.)
[0050] Further, the invention relates to [29] the additive liquid
for polishing slurry according to [23], wherein the polysilicon
polishing inhibitor is an alkoxylated linear aliphatic alcohol.
Further, the invention relates to [30] the additive liquid for
polishing slurry according to [23], which contains two or more
types of the polysilicon polishing inhibitor.
[0051] Further, the invention relates to [31] the additive liquid
for polishing slurry according to [30], wherein the polysilicon
polishing inhibitor includes two or more compounds selected from
the water-soluble polymer, polyethylene glycol, an oxyethylene
adduct of an acetylene-based diol, a compound represented by the
general formula (III), a compound represented by the general
formula (IV), and an alkoxylated linear aliphatic alcohol.
[0052] Further, the invention relates to [32] the additive liquid
for polishing slurry according to any of [23] through [31], which
further contains at least one selected from polyacrylic acid,
polyacrylate, and a copolymer containing acrylate.
[0053] Further, the invention relates to [33] a polishing method
using the polishing slurry for silicon oxide according to any of
[1] through [21], wherein the object to be polished is held against
a polishing pad with the surface thereof to be polished facing the
polishing pad, and polished by being slid relative to the polishing
pad while the polishing slurry is supplied between the polishing
pad and the surface to be polished.
[0054] The invention provides a polishing slurry and a polishing
method which are capable of polishing a silicon oxide film on a
polysilicon film at a high speed, and inhibiting the progress of
polishing of a polysilicon film in exposed parts in a CMP technique
in the manufacturing process of a semiconductor in which a silicon
oxide film is polished.
[0055] Disclosure of the invention is related to the subject
described in Japanese Patent Application No. 2005-327422 which was
filed on Nov. 11, 2005, and the disclosure of which is incorporated
herein by reference.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0056] The embodiment of the invention is described in detail
below.
[0057] As a result of the eager investigation by the inventors of
the present invention concerning the polishing of a silicon oxide
film on a polysilicon film in the planarization process of a
semiconductor, it has been found that a polishing slurry comprising
an abrasive, water, and a inhibitor for inhibiting polishing of a
polysilicon film is capable of keeping a high polishing rate for a
silicon oxide film and a low polishing rate for a polysilicon film,
and thereby achieving a high polishing rate ratio (selective ratio)
between them. Thus the present invention has been accomplished. It
has been also found that the selective ratio is increased by
adjusting the pH of the polishing slurry.
[0058] The abrasive used in the invention may be cerium oxide,
silicon oxide, or the like, and is preferably cerium oxide. Cerium
oxide particles are not limited as to their manufacturing method,
but the average primary particle diameter of cerium oxide is
preferable 5 nm or more and 300 nm or less. This is because,
regarding a cerium oxide polishing slurry used for polishing of a
silicon oxide film formed by a TEOS-CVD method or the like, cerium
oxide having a larger primary particle diameter and less crystal
distortion or higher crystallinity allows faster polishing, but
tends to give polishing scratches. The term primary particles
refers to particles corresponding to crystallites surrounded by
grain boundaries which are measured and observed with a SEM
(scanning electron microscope).
[0059] In the invention, the method for preparing cerium oxide
powder may be sintering of a cerium compound such as carbonate,
nitrate, sulfate, or oxalate, or oxidation with hydrogen peroxide
or the like. The sintering temperature is preferably 350.degree. C.
or higher and 900.degree. C. or lower. Since cerium oxide particles
prepared by the above-described methods tend to cause aggregation,
they are preferably pulverized by a mechanical means. As a
pulverizing method, a dry milling method by a jet mill or the like,
or a wet milling method with a planet bead mill or the like is
preferable.
[0060] The median value of the secondary particle diameter of the
abrasive is preferably 0.03 to 0.5 .mu.m, and more preferably 0.05
to 0.3 .mu.m. This is because that if the median value of the
secondary particle diameter is less than 0.03 .mu.m, the polishing
rate tends to be low, and if more than 0.5 .mu.m, the abrasive
tends to give polishing scratches on the film surface to be
polished.
[0061] The abrasive is dispersed in water to obtain a slurry. The
method for dispersion may be dispersion with an ordinary stirrer,
or may use a homogenizer, ultrasonic disperser, wet ball mill or
the like.
[0062] The concentration of the abrasive in the polishing slurry is
not limited, but preferably in the range of 0.1% by mass or more
and 20% by mass or less, more preferably in the range of 0.2% by
mass or more and 10% by mass or less, and particularly preferably
in the range of 0.5% by mass or more and 5% by mass or less from
the viewpoint of manageability of the dispersion liquid
(slurry).
[0063] The slurry may contain a dispersant for the abrasive. Since
the dispersant for the abrasive is used for polishing of a
semiconductor device, the content of alkali metals such as sodium
and potassium ions, halogens, and sulfur in the dispersant is
preferably 10 ppm or less. A preferable example is a polymer
dispersant containing an acrylic acid ammonium salt as a
copolymerization component.
[0064] The addition amount of the dispersant is preferably in the
range of 0.01 parts by mass or more and 5.0 parts by mass or less
relative to 100 parts by mass of the abrasive particles in
consideration of the relationship between the dispersibility of the
particles in the polishing slurry and prevention of settling, and
the relationship between polishing scratches and the addition
amount of the dispersant. The weight average molecular weight of
the dispersant is preferably 100 to 50,000, and more preferably
1,000 to 10,000. This is because if the molecular weight of the
dispersant is less than 100, a sufficient polishing rate is hard to
be achieved during polishing of a silicon oxide film, and if the
molecular weight of the dispersant is more than 50,000, the
viscosity tends to be high, and the preservation stability of the
polishing slurry tends to decrease. The weight average molecular
weight is a value determined by gel permeation chromatography, and
converted to standard polystyrene.
[0065] Since the abrasive in the thus prepared polishing slurry for
silicon oxide of the invention (hereinafter also referred to as
polishing slurry) has a particle diameter distribution, 99% by
volume (D99) of the whole particles is preferably 1.0 .mu.m or
less. If D99 is more than 1.0 .mu.m, many scratches (polishing
scratches) may occur.
[0066] The median value of the secondary particle diameter of the
abrasive in the polishing slurry) may be determined by a light
scattering method using, for example, a particle size analyzer
(e.g., Mastersizer Micro Plus, manufactured by Malvern
Instruments).
[0067] The content of coarse particles of 3 .mu.m or more in the
total solid content in the polishing slurry is preferably lower.
When the content of particles of 3 .mu.m or more is 500 ppm or less
relative to the total solid content, it is preferable because the
scratch reduction effect is evident. When the content of particles
of 3 .mu.m or more is 200 ppm or less relative to the total solid
content, it is more preferable because the scratch reduction effect
is higher. When the content of particles of 3 .mu.m or more is 100
ppm or less relative to the total solid content, it is further
preferable because the scratch reduction effect is highest.
[0068] The content of large particles of 3 .mu.m or more is
determined by mass determination of particles captured by a filter
having pore diameter of 3 .mu.m. The means for reducing the content
of large particles may be filtration or classification, but is not
limited to them.
[0069] The polysilicon film polishing inhibitor of the invention is
preferably a nonionic water-soluble polymer. The reason is as
follows: in a measurement of zeta potential on the surface of a
silicon oxide film, which is to be polished by the polishing slurry
of the invention, a negative zeta potential of about -20 mV or less
is indicated in a large pH range, while a polysilicon
(polycrystalline silicon) film, which is to be hindered from being
polished, has a pH of 8 or less and a zeta potential of about -10
mV or less, which is relatively close to 0. A nonionic
water-soluble polymer is considered to more readily adhere to the
surface of a polysilicon film than the surface of a silicon oxide
film.
[0070] The weight average molecular weight of the water-soluble
polymer is preferably 500 or more and 3,000,000 or less, and more
preferably 1,000 or more and 1,000,000 or less. This is based on
the assumption that those having a higher weight average molecular
weight are more effective in inhibiting polishing upon adhesion to
the surface of a polysilicon film. However, if the weight average
molecular weight is excessive, the viscosity of the polishing
slurry increases, which causes defects such as sedimentation of the
abrasive. Accordingly, the lower limit is preferably 500 or more,
more preferably 1,000 or more, and particularly preferably 2,000 or
more. The upper limit is preferably 50,000 or less, more preferably
20,000 or less, and particularly preferably 10,000 or less.
[0071] Typical examples of the polysilicon film polishing inhibitor
include water-soluble polymers group having a N-monosubstituted or
N,N-disubstituted skeleton substituted by any member selected from
the group consisting of acrylamide, methacrylamide, and
.alpha.-substituted derivatives thereof.
[0072] Among the water-soluble polymers, a polymer or copolymer
using at least one selected from the polymerizable monomer
represented by the following general formulae (I) and (II) is
preferable. Also preferable is a copolymer using both of the
polymerizable monomers represented by the general formulae (I) and
(II). The polymerizable monomers represented by the general
formulae (I) and (II) may be copolymerized with other polymerizable
monomers such as acrylic acid, acrylic esters of C.sub.1 to
C.sub.18, methacrylic acid, methacrylic acid esters of C.sub.1 to
C.sub.18, acrylamide, vinyl alcohol, acrylonitrile, vinyl
pyrrolidone, vinyl pyridine, vinyl acetate, maleic acid, fumaric
acid, itaconic acid, and p-styrenecarboxylic acid. The polymer or
copolymer preferably has a weight average molecular weight of 500
or more, and is preferably prepared by radical polymerization or
the like. ##STR7##
[0073] In the general formula (I), R.sub.1 represents a hydrogen
atom, methyl group, phenyl group, benzyl group, chloro group,
difluoromethyl group, trifluoromethyl group, or cyano group, and
R.sub.2 and R.sub.3 each independently represents a hydrogen atom,
alkyl chain of C.sub.1 to C.sub.18, methylol group, or acetyl group
with the proviso that the case where both of them simultaneously
represent a hydrogen atomis excluded. In the general formula (II),
R.sub.1 represents a hydrogen atom, methyl group, phenyl group,
benzyl group, chloro group, difluoromethyl group, trifluoromethyl
group, or cyano group, R.sub.4 represents a morpholino group,
thiomorpholino group, pyrrolidino group, or piperidino group.
[0074] Examples of the water-soluble polymer having a
N-monosubstituted or N,N-disubstituted skeleton include: compounds
having a N-monosubstituted skeleton such as N-methylacrylamide,
N-ethylacrylamide, N-propylacrylamide, N-isopropylacrylamide,
N-butylacrylamide, N-isobutylacrylamide, N-tertiarybutylacrylamide,
N-heptylacrylamide, N-octylacrylamide, N-tertiaryoctylacrylamide,
N-dodecylacrylamide, N-octadecylacrylamide, N-methylolacrylamide,
N-acetylacrylamide, N-diacetone acrylamide, N-methylmethacrylamide,
N-ethylmethacrylamide, N-propylmethacrylamide,
N-isopropylmethacrylamide, N-butylmethacrylamide,
N-isobutylmethacrylamide, N-tertiarybutylmethacrylamide,
N-heptylmethacrylamide, N-octylmethacrylamide,
N-tertiaryoctylmethacrylamide, N-dodecylmethacrylamide,
N-octadecylmethacrylamide, N-methylolmethacrylamide,
N-acetylmethacrylamide, and N-diacetone methacrylamide; and
compounds having a N,N-disubstituted skeleton such as
N,N-dimethylacrylamide, N,N-diethylacrylamide,
N,N-dipropylacrylamide, N,N-diisopropylacrylamide,
N,N-dibutylacrylamide, N,N-diisobutylacrylamide,
N,N-ditertiarybutylacrylamide, N,N-diheptylacrylamide,
N,N-dioctylacrylamide, N,N-ditertiaryoctylacrylamide,
N,N-didodecylacrylamide, N,N-dioctadecylacrylamide,
N,N-dimethylolacrylamide, N,N-diacetylacrylamide, N,N-diacetone
acrylamide, N,N-dimethylmethacrylamide, N,N-diethylmethacrylamide,
N,N-dipropylmethacrylamide, N,N-diisopropylmethacrylamide,
N,N-dibutylmethacrylamide, N,N-diisobutylmethacrylamide,
N,N-ditertiarybutylmethacrylamide, N,N-diheptylmethacrylamide,
N,N-dioctylmethacrylamide, N,N-ditertiaryoctylmethacrylamide,
N,N-didodecylmethacrylamide, N,N-dioctadecylmethacrylamide,
N,N-dimethylolmethacrylamide, N,N-diacetylmethacrylamide,
N,N-diacetone methacrylamide, acryloylpiperidine,
acryloylmorpholine, acryloylthiomorpholine, and
acryloylpyrrolidine. These compounds may be used alone or in
combination of two or more of them.
[0075] Other examples of the polysilicon film polishing inhibitor
of the invention include polyethylene glycol which is a
water-soluble polymer.
[0076] Other examples of the polysilicon film polishing inhibitor
of the invention also include an oxyethylene adduct of an
acetylene-based diol which is a water-soluble polymer. Examples of
the oxyethylene adduct of an acetylene-based diol include compounds
such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol,
2,4,7,9-tetramethyl-5-decyne-4,7-diol-dipolyoxyethylene ether, and
2,4,7,9-tetramethyl-5-decyne-4,7-diol-monopolyoxyethylene ether.
Among them, 2,4,7,9-tetra methyl-5-decyne-4,
7-diol-dipolyoxyethylene ether is particularly preferable from the
view point of both of water solubility and decrease of surface
tension.
[0077] Other examples of the polysilicon film polishing inhibitor
of the invention also include a compound represented by the
following general formula (III) and/or an organic compound having
an acetylene bond represented by the following general formula
(IV).
[0078] [Formula 11] R.sup.1--C.ident.C--R.sup.2 (III)
[0079] (In the general formula (III), R.sup.1 represents a hydrogen
atom or substituted or unsubstituted alkyl group having 1 to 5
carbon atoms, R.sup.2 represents a substituted or unsubstituted
alkyl group having 4 to 10 carbon atoms.) ##STR8##
[0080] (In the general formula (IV), R.sup.3 to R.sup.6 each
independently represent a hydrogen atom or substituted or
unsubstituted alkyl group having 1 to 5 carbon atoms, R.sup.7 and
R.sup.8 each independently represent a substituted or unsubstituted
alkylene group having 1 to 5 carbon atoms, and m and n each
independently represents 0 or a positive number.)
[0081] Other examples of the polysilicon film polishing inhibitor
of the invention also include an alkoxylated linear aliphatic
alcohol.
[0082] The pH of the polishing slurry using the polysilicon film
polishing inhibitor is preferably 5.0 or more and 8.0 or less, and
more preferably 6.0 or more and 7.0 or less. If the pH is less than
5, the polishing rate for a polysilicon film tends to increase, and
if the pH is more than 8, the polishing rate for a silicon oxide
film tends to decrease.
[0083] In the invention, the pH of the polishing slurry is measured
as follows: two-point calibration is performed using standard
buffer solutions (phthalate pH buffer solution having a pH of 4.21
(25.degree. C.) and a neutral phosphate pH buffer solution having a
pH of 6.86 (25.degree. C.)) with a pH meter (e.g., model number
PH81 manufactured by Yokogawa Electric Corporation), subsequently
the electrode is immersed in the polishing slurry, and the pH is
measured after it becomes stable after a lapse of at least two
minutes. The pH may be adjusted with an alkaline component or acid
such as ammonia or tetramethyl ammonium hydroxide (TMAH).
[0084] The polysilicon film polishing inhibitor may be used alone,
but preferably in combination of two or more of them, and
particularly preferably contains two or more members selected from
the water-soluble polymer compound having a N-monosubstituted or
N,N-disubstituted skeleton substituted by any member selected from
the group consisting of acrylamide, methacrylamide, and
.alpha.-substituted derivatives thereof, polyethylene glycol, an
oxyethylene adduct of an acetylene-based diol, a compound
represented by the general formula (III), a compound represented by
the general formula (IV), and an alkoxylated linear aliphatic
alcohol.
[0085] The addition amount of the polysilicon film polishing
inhibitor is preferably in the range of 0.005% by mass or more and
2% by mass or less relative to 100 parts by mass of the polishing
slurry, or 0.005 to 2% by mass in the polishing slurry. If the
amount is less than 0.005% by mass, the inhibitory effect on
polishing of a polysilicon film is low, and if more than 2% by
mass, the polishing rate for a silicon oxide film may decrease, and
flowability may deteriorate due to gelation.
[0086] Examples of other polysilicon film polishing inhibitors
which may be used in the invention include polyvinyl pyrrolidone or
copolymers containing vinyl pyrrolidone (hereinafter they are
collectively referred to as polyvinyl pyrrolidones). The addition
amount of polyvinyl pyrrolidones is preferably in the range of
0.005% by mass or more and 5% by mass or less relative to the
polishing slurry. The weight average molecular weight of polyvinyl
pyrrolidones is preferably 10,000 to 1,200,000. If the molecular
weight is less than 10,000, planarization property tends to be
insufficient, and if more than 1,200,000, the abrasive tends to
cause aggregation. The pH of the polishing slurry using a polyvinyl
pyrrolidone is preferably 5.0 or more and 12.0 or less, and more
preferably 6.0 or more and 7.0 or less. If the pH is less than 5.0,
the polishing rate for a polysilicon film tends to be excessive,
and if the pH is more than 12, the polishing rate for a polysilicon
film tends to decrease. The polyvinyl pyrrolidones may be combined
with the above-described polysilicon film polishing inhibitor.
[0087] The polishing slurry of the invention may be combined with
other water-soluble polymers. Examples of the other water-soluble
polymers are not particularly limited, and include polysaccharides
such as alginic acid, pectin acid, carboxy methyl cellulose, agar,
curdlan and pullulan; polycarboxylic acids and salts thereof such
as polyasparatic acid, polyglutamic acid, polylysine, polymalic
acid, polymethacrylic acid, polymethacrylic acid ammonium salt,
polymethacrylic acid sodium:salt, polyamide acid, polymaleic acid,
polyitaconic acid, polyfumaric acid, poly(p-styrene carboxylic
acid), polyacrylic acid, polyacrylamide, amino polyacrylamide,
polyacrylic acid ammonium salt, sodium polyacrylate salt, polyamide
acid, polyamide acid ammonium salt, polyamide acid sodium salt, and
polyglyoxalic acid; and vinyl polymers such as polyvinyl alcohol
and polyacrolein. The weight average molecular weight is preferably
500 or more, and preferably 50,000 or less for avoiding the
occurrence of excessive viscosity and deterioration of the
preservation stability of the polishing slurry.
[0088] In particular, it is preferable to use at least one selected
from polyacrylic acid, polyacrylate, and copolymer containing
acrylate as an additive for improving the flatness of the oxide
film surface. The addition amount of the polyacrylic acid,
polyacrylate, and copolymer containing acrylate is preferably in
the range of 0.01% by mass or more and 5% by mass or less relative
to 100 parts by mass of the polishing slurry. This is because that
if the amount is less than 0.01% by mass, the effect of improving
the flatness is low, and if more than 5% by mass, the abrasive
tends to cause aggregation.
[0089] Further, the polysilicon film polishing inhibitor may be
combined with the additive for improving global flatness. More
specifically, the water-soluble polysilicon film polishing
inhibitor will not cause any problem even if it is combined with an
additive for improving flatness containing a copolymer containing
polyacrylic acid, polyacrylate, or acrylate.
[0090] The additive liquid for polishing slurry of the invention is
an additive liquid for polishing slurry used in a polishing slurry
for polishing a silicon oxide film on polysilicon, and contains a
polysilicon polishing inhibitor and water.
[0091] The polishing slurry for silicon oxide of the invention may
be preserved as a two-liquid polishing slurry in which a slurry
containing an abrasive and water is separated from an additive
liquid containing a polysilicon polishing inhibitor and water, or
may be preserved as a one-liquid polishing slurry containing an
additive liquid or a polysilicon polishing inhibitor. When the
polishing slurry is preserved as a two-liquid polishing slurry, its
planarization property and polishing rate can be adjusted by
arbitrarily changing the formulation of the two-liquids. When a
substrate is polished with the two-liquid polishing slurry, the
additive liquid and the slurry are sent in different lines, and the
lines are merged into one to mix the liquids immediately before the
outlet of the feeding line, and the mixture is supplied onto the
polishing platen, or the additive is mixed with the slurry
immediately before polishing. For two-liquid polishing slurries,
the additive for improving flatness is preferably contained in the
additive liquid.
[0092] Examples of the method for preparing a silicon oxide film
which can be polished with the polishing slurry of the invention
include a low-pressure CVD method and a plasma CVD method.
Formation of a silicon oxide film by the low-pressure CVD method is
achieved by an oxidation reaction of SiH.sub.4--O.sub.2 system at a
low temperature of 400.degree. C. or lower using monosilane
(SiH.sub.4) as an Si source, and oxygen (O.sub.2) as an oxygen
source. According to circumstances, CVD may be followed by heat
treatment at a temperature of 1000.degree. C. or lower. When
phosphorus (P) is doped in order to planarize the surface by
high-temperature reflowing, it is preferable to use a reaction gas
of SiH.sub.4--O.sub.2--PH.sub.3 system. The plasma CVD method has
an advantage that any chemical reaction which requires a high
temperature under normal heat equilibrium can be carried out at a
low temperature. There are two types of methods for generating
plasma: capacitive coupling type and inductive coupling type.
Examples of the reaction gas include a gas of SiH.sub.4--N.sub.2O
system using SiH.sub.4 as an Si source and N.sub.2O as an oxygen
source, and a gas of TEOS--O.sub.2 system using tetraethoxysilane
(TEOS) as an Si source (TEOS-plasma CVD method). The substrate
temperature is preferably in the range of 250 to 400.degree. C.,
and the reaction pressure is preferably in the range of 67 to 400
Pa. Thus, the silicon oxide film may be doped with an element such
as phosphorus or boron.
[0093] In the same manner, formation of a polysilicon film by the
CVD method is performed using SiH.sub.4 as an Si source at a
substrate temperature of 600 to 1000.degree. C.
[0094] The polishing method of the invention is a method for
polishing an object to be polished, wherein the object to be
polished is held against a polishing pad with its surface to be
polished facing the polishing pad, and polished by being slid
relative to the polishing pad while a polishing slurry is supplied
between the polishing pad and the surface to be polished, and the
polishing slurry for silicon oxide of the invention is used as the
polishing slurry. Examples of the object to be polished include a
substrate involved in the manufacture of a semiconductor device,
for example a substrate comprising a polysilicon film having formed
thereon a silicon oxide film.
[0095] The ratio of the polishing rate for a silicon oxide film to
the polishing rate for a polysilicon film (selective ratio) is
preferably 10 or more from the viewpoint of easy stop control of
polishing. The polishing rate for a silicon oxide film is
preferably 50 nm/min or more, and more preferably 100 nm/min or
more. The polishing rate for polysilicon is preferably 10 nm/min or
less, and more preferably 5 nm/min or less. The polishing apparatus
may be a common polishing apparatus comprising a holder for holding
a substrate and a platen equipped with a motor or the like with
variable rotation number, to which a polishing cloth (pad) can be
attached. The polishing cloth may be a common nonwoven fabric,
foamed polyurethane, or porous fluorocarbon resin, and is not
particularly limited. The polishing cloth is preferably
groove-processed for retaining the polishing slurry.
[0096] The polishing conditions are not limited, but the rotation
rate of the platen is preferably as lows as 200 min.sup.-1 or less
for preventing the substrate from jumping out, and the pressure to
be applied to the substrate is preferably 9.8.times.10.sup.4 Pa or
less in order to prevent the development of scratches. During
polishing, the polishing slurry is continuously supplied to the
polishing cloth with a pump or the like. The amount of the
polishing slurry to be supplied is not particularly limited, but is
preferably in an amount so that the surface of the polishing cloth
is constantly covered with the polishing slurry. The substrate
after completion of polishing is preferably thoroughly washed in
running water, and dried after water droplets adhering to the
substrate are knocked off with a spin dryer or the like.
EXAMPLES
[0097] The invention is further illustrated by following Examples.
The invention is not limited to these Examples.
[0098] (Preparation of Cerium Oxide Particles)
[0099] 2 kg of cerium carbonate hydrate was placed in a container
made of platinum, followed by sintering at 800.degree. C. for 2
hours in air to obtain about 1 kg of a yellowish white powder.
Phase identification of this powder was made by X-ray
diffractometry to confirm that it was cerium oxide. The sintered
powder had particle diameters of 30 to 100 .mu.m. The surface of
the sintered particles was observed with a scanning electron
microscope, where grain boundaries of cerium oxide were seen.
Diameters of cerium oxide primary particles surrounded by the grain
boundaries were measured to find that the median diameter and
maximum diameter in their particle size distribution were 190 nm
and 500 nm, respectively. 1 kg of the cerium oxide powder was
pulverized by a dry process with a jet mill. The pulverized
particles were observed with a scanning electron microscope to find
that large pulverization residue particles of 1 .mu.m to 3 .mu.m
and pulverization residue particles of 0.5 .mu.m to 1 .mu.m were
present in a mixed state in addition to small particles having the
same size as the primary particle diameter.
[0100] (Preparation of Cerium Oxide Slurry)
[0101] 1 kg of the cerium oxide particles prepared above was mixed
with 23 g of an aqueous solution of polyacrylic acid ammonium salt
(40% by mass) and 8977 g of deionized water, followed by ultrasonic
dispersion for 10 minutes while being stirred. The obtained slurry
was filtered through a 1-micron filter, and followed by further
addition of deionized water to obtain a 5% by mass slurry. The
slurry had a pH of 8.3. The slurry was diluted to an appropriate
concentration in order to examine the slurry particles with a laser
diffraction particle size analyzer to find that the median value of
the particle diameter was 190 nm.
[0102] (Procurement of Water-Soluble Polymer)
[0103] Water-Soluble Polymer 1
[0104] Polyvinyl pyrrolidone manufactured by Wako Pure Chemical
Industries, Ltd. (reagent, K-30) was procured.
[0105] Water-Soluble Polymer 2
[0106] Polyvinyl pyrrolidone manufactured by Wako Pure Chemical
Industries, Ltd. (reagent, K-90) was procured.
[0107] Water-Soluble Polymer 3-1 [Synthesis Example 1]
[0108] 280 g of deionized water and 20 g of 2-propanol were placed
in a 1-L flask, heated to 90.degree. C. while being stirred in a
nitrogen gas atmosphere, followed by injection of a solution of 1 g
of a polymerization initiator (trade name: V-601, manufactured by
Wako Pure Chemical Industries, Ltd.) in 100 g acryloyl morpholine
over a period of 2 hours. Subsequently the flask was incubated at
90.degree. C. for 5 hours, cooled, and taken out to obtain a
water-soluble polymer solution. The concentration of the
water-soluble polymer in the solution was 25.3%.
[0109] Water-Soluble Polymer 3-2 [Synthesis Example 2]
[0110] Synthesis was carried out using 50 g of
N,N-diethylacrylamide and 50 g of acryloyl morpholine by the method
of Synthesis example 1 to obtain a water-soluble polymer solution.
The concentration of the water-soluble polymer in the solution was
25.1%.
[0111] Water-Soluble Polymer 3-3 [Synthesis Example 3]
[0112] Synthesis was carried out using 50 g of
N,N-diethylacrylamide and 50 g of N,N-dimethylacrylamide by the
method of Synthesis example 1 to obtain a water-soluble polymer
solution. The concentration of the water-soluble polymer in the
solution was 25.0%.
[0113] Water-Soluble Polymer 3-4 [Synthesis Example 4]
[0114] Synthesis was carried out using 100 g of
N,N-dimethylacrylamide by the method of Synthesis example 1 to
obtain a water-soluble polymer solution. The concentration of the
water-soluble polymer in the solution was 25.1%.
[0115] Water-Soluble Polymer 4
[0116] Polyethylene glycol manufactured by Dai-Ichi Kogyo Seiyaku
Co., Ltd. (reagent, PEG-4000) was procured.
[0117] Water-Soluble Polymer 5
[0118] As an oxyethylene adduct of an acetylene-based diol,
2,4,7,9-tetramethyl-5-decyne-4,7-diol was procured.
[0119] Water-Soluble Polymer 6
[0120] As an alkoxylated linear aliphatic alcohol, a reagent
manufactured by BASF (LF-401) was procured.
[0121] Water-Soluble Polymer 7
[0122] Polyacrylic acid (trade name: JULIMER AC-10S, manufactured
by Nihonjunyaku Co., Ltd.) was procured.
[0123] (Preparation of Polishing Slurry)
[0124] Polishing Slurry 1
[0125] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 1 g of polyvinyl pyrrolidone of
the water-soluble polymer 1 as a polysilicon film polishing
inhibitor and 2399 g of deionized water to obtain a polishing
slurry (cerium oxide: 1% by mass). The polishing slurry was
adjusted to pH 6.5 with a trace amount of nitric acid.
[0126] Polishing Slurry 2
[0127] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 2 g of polyvinyl pyrrolidone of
the water-soluble polymer 2 as a polysilicon film polishing
inhibitor and 2398 g of deionized water to obtain a polishing
slurry (cerium oxide: 1% by mass). The polishing slurry was
adjusted to pH 6.5 with a trace amount of nitric acid.
[0128] Polishing Slurry 3
[0129] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 0.5 g of polyvinyl pyrrolidone
of the water-soluble polymer 1 as a polysilicon film polishing
inhibitor, 70 g of a solution of the water-soluble polymer 7 as a
highly planarizing agent for oxide film, and 2329.5 g of deionized
water to obtain a polishing slurry (cerium oxide: 1% by mass). The
polishing slurry was adjusted to pH 6.5 with a trace amount of
ammonia.
[0130] Polishing Slurry 4
[0131] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 20 g of a solution of the
water-soluble polymer 3-1 (synthesis example 1) as a polysilicon
polishing inhibitor and 2380 g of deionized water to obtain a
polishing slurry (cerium oxide: 1% by mass). The polishing slurry
was adjusted to pH 6.5 with a trace amount of nitric acid.
[0132] Polishing Slurry 5
[0133] A polishing slurry was prepared in the same manner as
polishing slurry 4 except that a solution of the water-soluble
polymer 3-2 (synthesis example 2) was used as a polysilicon
polishing inhibitor in place of the water-soluble polymer 3-1
(synthesis example 1).
[0134] Polishing Slurry 6
[0135] A polishing slurry was prepared in the same manner as
polishing slurry 4 except that a solution of the water-soluble
polymer 3-3 (synthesis example 3) was used as a polysilicon
polishing inhibitor in place of the water-soluble polymer 3-1
(synthesis example 1).
[0136] Polishing Slurry 7
[0137] A polishing slurry was prepared in the same manner as
polishing slurry 4 except that a solution of the water-soluble
polymer 3-4 (synthesis example 4) was used as a polysilicon
polishing inhibitor in place of the water-soluble polymer 3-1
(synthesis example 1).
[0138] Polishing Slurry 8
[0139] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 10 g of a solution of the
water-soluble polymer 3-1 (synthesis example 1) as a polysilicon
film polishing inhibitor, 70 g of a solution of the water-soluble
polymer 7 as a highly planarizing agent for oxide film, and 2320 g
of deionized water to obtain a polishing slurry (cerium oxide: 1%
by mass). The polishing slurry was adjusted to pH 6.5 with a trace
amount of ammonia.
[0140] Polishing Slurry 9
[0141] A polishing slurry was prepared in the same manner as
polishing slurry 8 except that a solution of the water-soluble
polymer 3-4 (synthesis example 4) was used as a polysilicon
polishing inhibitor in place of the water-soluble polymer 3-1
(synthesis example 1).
[0142] Polishing Slurry 10
[0143] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 5 g of a solution of the
water-soluble polymer 4 as a polysilicon film polishing inhibitor,
70 g of a solution of the water-soluble polymer 7 as a highly
planarizing agent for oxide film, and 2325 g of deionized water to
obtain a polishing slurry (cerium oxide: 1% by mass). The polishing
slurry was adjusted to pH 6.5 with a trace amount of ammonia.
[0144] Polishing Slurry 11
[0145] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 5 g of a solution of the
water-soluble polymer 5 as a polysilicon film polishing inhibitor,
70 g of a solution of the water-soluble polymer 7 as a highly
planarizing agent for oxide film, and 2325 g of deionized water to
obtain a polishing slurry (cerium oxide: 1% by mass). The polishing
slurry was adjusted to pH 6.5 with a trace amount of ammonia.
[0146] Polishing Slurry 12
[0147] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 5 g of a solution of the
water-soluble polymer 6 as a polysilicon film polishing inhibitor,
70 g of a solution of the water-soluble polymer 7 as a highly
planarizing agent for oxide film, and 2325 g of deionized water to
obtain a polishing slurry (cerium oxide: 1% by mass). The polishing
slurry was adjusted to pH 6.5 with a trace amount of ammonia.
[0148] Polishing Slurry 13
[0149] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 2400 g of deionized water to
obtain a polishing slurry (cerium oxide: 1% by mass). The polishing
slurry was adjusted to pH 6.5 with a trace amount of ammonia.
[0150] Polishing Slurry 14
[0151] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 70 g of a solution of the
water-soluble polymer 7 as a highly planarizing agent for oxide
film and 2320 g of deionized water to obtain a polishing slurry
(cerium oxide: 1% by mass). The polishing slurry was adjusted to pH
6.5 with a trace amount of ammonia.
[0152] Polishing Slurry 15
[0153] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 12 g of a solution of the
water-soluble polymer 3-1 (synthesis example 1) as a polysilicon
polishing inhibitor and 2388 g of deionized water to obtain a
polishing slurry (cerium oxide: 1% by mass). The polishing slurry
was adjusted to pH 4.5 with a trace amount of nitric acid.
[0154] Polishing Slurry 16
[0155] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 60 g of a solution of the
water-soluble polymer 3-1 (synthesis example 1) as a polysilicon
polishing inhibitor and 2340 g of deionized water to obtain a
polishing slurry (cerium oxide: 1% by mass). The polishing slurry
was adjusted to pH 9.0 with a trace amount of ammonia.
[0156] Polishing Slurry 17
[0157] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 2400 g of deionized water to
obtain a polishing slurry (cerium oxide: 1% by mass). The polishing
slurry was adjusted to pH 4.5 with a trace amount of nitric
acid.
[0158] Polishing Slurry 18
[0159] 600 g of the cerium oxide slurry prepared above (solid
content: 5% by mass) was mixed with 2400 g of deionized water to
obtain a polishing slurry (cerium oxide: 1% by mass). The polishing
slurry was adjusted to pH 9.0 with a trace amount of ammonia.
Tables 1 through 3 show the composition and pH of the polishing
slurries.
[0160] (Evaluation of Polishing)
Example 1
[0161] The substrate below was subjected to CMP polishing under
following conditions while a polishing slurry of the polishing
slurry 1 was dropped on the pad attached to the platen, and
evaluated as described below.
[0162] <Substrates for Evaluation>
[0163] Substrate 1: A blanket substrate of 8 inch diameter
comprising a Si substrate having formed thereon a silicon oxide
film (P--TEOS) of 0.8 .mu.m thickness.
[0164] Substrate 2: A blanket substrate of 8 inch diameter
comprising a Si substrate having formed thereon a silicon oxide
film of 0.1 .mu.m thickness and a polysilicon film of 0.4 .mu.m
thickness in this order.
[0165] <Evaluation Conditions>
[0166] Polishing apparatus: MIRRA polishing machine, manufactured
by AMAT, platen diameter 600 mm, rotary type
[0167] Polishing pad: IC-1000/Suba 400 manufactured by Nitta Haas
Incorporated, foamed double layer pad with a concentric groove
[0168] Polishing pressure: 25 kPa
[0169] Platen rotation number: 98 min.sup.-1
[0170] Polishing slurry flow rate: 200 ml/min
[0171] Polishing time: 1 min
[0172] <Evaluation Item and Evaluation Method>
[0173] Silicon oxide polishing rate by CMP: Difference in the film
thickness of the substrate 1 before and after CMP was determined
with an optical film thickness measuring device.
[0174] Polysilicon polishing rate by CMP: Difference in the film
thickness of the substrate 2 before and after CMP was determined
with an optical film thickness measuring device.
[0175] The results of the evaluation indicate that the polishing
rate for a silicon oxide film was 160 nm/min, the polishing rate
for a polysilicon was 0.7 nm/min, and the ratio of the polishing
rate for a silicon oxide film to the polishing rate for a
polysilicon film was 228.
Example 2
[0176] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 2 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 250 nm/min, the polishing rate for a
polysilicon was 1.5 nm/min, and the ratio of the polishing rate for
a silicon oxide film to the polishing rate for a polysilicon film
was 167.
Example 3
[0177] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 3 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 90 nm/min, the polishing rate for a
polysilicon was 3.5 nm/min, and the ratio of the polishing rate for
a silicon oxide film to the polishing rate for a polysilicon film
was 26.
Example 4
[0178] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 4 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 270 nm/min, the polishing rate for a
polysilicon was 1.2 nm/min, and the ratio of the polishing rate for
a silicon oxide film to the polishing rate for a polysilicon film
was 225.
Example 5
[0179] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 5 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 250 nm/min, the polishing rate for a
polysilicon was 1 nm/min, and the ratio of the polishing rate for a
silicon oxide film to the polishing rate for a polysilicon film was
250.
Example 6
[0180] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 6 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 200 nm/min, the polishing rate for a
polysilicon was 1.5 nm/min, and the ratio of the polishing rate for
a silicon oxide film to the polishing rate for a polysilicon film
was 133.
Example 7
[0181] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 7 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 190 nm/min, the polishing rate for a
polysilicon was 1.1 nm/min, and the ratio of the polishing rate for
a silicon oxide film to the polishing rate for a polysilicon film
was 173.
Example 8
[0182] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 8 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 160 nm/min, the polishing rate for a
polysilicon was 0.8 nm/min, and the ratio of the polishing rate for
a silicon oxide film to the polishing rate for a polysilicon film
was 200.
Example 9
[0183] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 3 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 170 nm/min, the polishing rate for a
polysilicon was 1 nm/min, and the ratio of the polishing rate for a
silicon oxide film to the polishing rate for a polysilicon film was
170.
Example 10
[0184] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 10 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 180 nm/min, the polishing rate for a
polysilicon was 1 nm/min, and the ratio of the polishing rate for a
silicon oxide film to the polishing rate for a polysilicon film was
180.
Example 11
[0185] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 11 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 180 nm/min, the polishing rate for a
polysilicon was 2 nm/min, and the ratio of the polishing rate for a
silicon oxide film to the polishing rate for a polysilicon film was
90.
Example 12
[0186] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 12 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 150 nm/min, the polishing rate for a
polysilicon was 1 nm/min, and the ratio of the polishing rate for a
silicon oxide film to the polishing rate for a polysilicon film was
150.
Comparative Example 1
[0187] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 13 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 410 nm/min, the polishing rate for a
polysilicon was 90 nm/min, and the ratio of the polishing rate for
a silicon oxide film to the polishing rate for a polysilicon film
was 4.6.
Comparative Example 2
[0188] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 14 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 260 nm/min, the polishing rate for a
polysilicon was 60 nm/min, and the ratio of the polishing rate for
a silicon oxide film to the polishing rate for a polysilicon film
was 4.3.
Example 13
[0189] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 15 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 22 nm/min, the polishing rate for a
polysilicon was 0.8 nm/min, and the ratio of the polishing rate for
a silicon oxide film to the polishing rate for a polysilicon film
was 27.5.
Example 14
[0190] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 16 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 280 nm/min, the polishing rate for a
polysilicon was 35 nm/min, and the ratio of the polishing rate for
a silicon oxide film to the polishing rate for a polysilicon film
was 8.0.
Comparative Example 3
[0191] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 17 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 435 nm/min, the polishing rate for a
polysilicon was 75 nm/min, and the ratio of the polishing rate for
a silicon oxide film to the polishing rate for a polysilicon film
was 5.8.
Comparative Example 4
[0192] The polishing rates for a silicon oxide film and a
polysilicon film were evaluated using a polishing slurry of the
polishing slurry 18 under the same conditions as Example 1. The
results of the evaluation indicate that the polishing rate for a
silicon oxide film was 432 nm/min, the polishing rate for a
polysilicon was 110 nm/min, and the ratio of the polishing rate for
a silicon oxide film to the polishing rate for a polysilicon film
was 3.9. Tables 1 through 3 show the polishing rate and polishing
rate ratio of Examples and Comparative Examples. TABLE-US-00001
TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Polishing slurry
1 2 3 4 5 6 7 Cerium oxide (5 wt %) 600 600 600 600 600 600 600
Water-soluble polymer 1 1 -- 0.5 -- -- -- -- Water-soluble polymer
2 -- 2 -- -- -- -- -- Water-soluble polymer 3-1 -- -- -- 20 -- --
-- Water-soluble polymer 3-2 -- -- -- -- 20 -- -- Water-soluble
polymer 3-3 -- -- -- -- -- 20 -- Water-soluble polymer 3-4 -- -- --
-- -- -- 20 Water-soluble polymer 7 -- -- 70 -- -- -- -- Deionized
water 2399 2398 2329.5 2380 2380 2380 2380 pH 6.5 6.5 6.5 6.5 6.5
6.5 6.5 Polishing rate for silicon oxide (nm/minute) 160 250 90 270
250 200 190 Polishing rate for polysilicon (nm/minute) 0.7 1.5 3.5
1.2 1 1.5 1.1 Polishing rate ratio of silicon oxide to polysilicon
228 167 26 225 250 133 173
[0193] TABLE-US-00002 TABLE 2 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12
Polishing slurry 8 9 10 11 12 Cerium oxide (5 wt %) 600 600 600 600
600 Water-soluble polymer 1 -- -- -- -- -- Water-soluble polymer 2
-- -- -- -- -- Water-soluble polymer 3-1 10 -- -- -- --
Water-soluble polymer 3-2 -- -- -- -- -- Water-soluble polymer 3-3
-- -- -- -- -- Water-soluble polymer 3-4 -- 10 -- -- --
Water-soluble polymer 4 -- -- 5 -- -- Water-soluble polymer 5 -- --
-- 5 -- Water-soluble polymer 6 -- -- -- -- 5 Water-soluble polymer
7 70 70 70 70 70 Deionized water 2320 2320 2325 2325 2325 pH 6.5
6.5 6.5 6.5 6.5 Polishing rate for silicon oxide (nm/minute) 160
170 180 180 150 Polishing rate for polysilicon (nm/minute) 0.8 1 1
2 1 Polishing rate ratio of silicon oxide to polysilicon 200 170
180 90 150
[0194] TABLE-US-00003 TABLE 3 Comp. Comp. Comp. Comp. Ex. 1 Ex. 2
Ex. 13 Ex. 14 Ex. 3 Ex. 4 Polishing slurry 13 14 15 16 17 18 Cerium
oxide (5 wt %) 600 600 600 600 600 600 Water-soluble polymer 1 --
-- -- -- -- -- Water-soluble polymer 2 -- -- -- -- -- --
Water-soluble polymer 3-1 -- -- 12 60 -- -- Water-soluble polymer
3-2 -- -- -- -- -- -- Water-soluble polymer 3-3 -- -- -- -- -- --
Water-soluble polymer 3-4 -- -- -- -- -- -- Water-soluble polymer 7
-- 70 -- -- -- -- Deionized water 2400 2330 2388 2340 2400 2400 pH
6.5 6.5 4.5 9.0 4.5 9.0 Polishing rate for silicon oxide
(nm/minute) 410 260 22 280 435 432 Polishing rate for polysilicon
(nm/minute) 90 60 0.8 35 75 110 Polishing rate ratio of silicon
oxide to polysilicon 4.6 4.3 27.5 8.0 5.8 3.9
[0195] Examples 1 through 14 of the invention exhibited a high
polishing rate for a silicon oxide film and a low polishing rate
for polysilicon, and achieved a sufficiently large polishing rate
ratio between a silicon oxide film and polysilicon, wherein
polysilicon is applicable as a stopper. The polishing rate for an
oxide film was rather low at pH 4.5 in Example 13, and the
polishing rate for a polysilicon film was rather high at pH 9 in
Example 14, indicating that higher practicality is achieved in the
range of pH 5 to 8. On the other hand, in Comparative Examples 1,
3, and 4 in which no polysilicon polishing inhibitor was used, the
polishing rate for a silicon oxide film was high, but the polishing
rate for polysilicon was also high, wherein polysilicon is
inapplicable as a stopper. In Comparative Example 2 in which no
polysilicon polishing inhibitor was used but an additive was used,
the polishing rate for polysilicon was so high that the polishing
rate ratio between a silicon oxide film and polysilicon was not
large.
[0196] As described above, the invention provides a polishing
slurry and a polishing method which are capable of polishing a
silicon oxide film on a polysilicon film at a high speed, and
inhibiting the progress of polishing of a polysilicon film in
exposed parts in a CMP technique in the manufacturing process of a
semiconductor in which a silicon oxide film is polished.
* * * * *