U.S. patent application number 09/983271 was filed with the patent office on 2002-06-27 for polishing composition.
Invention is credited to Hagihara, Toshiya, Hashimoto, Ryoichi, Yoneda, Yasuhiro, Yoshida, Hiroyuki.
Application Number | 20020081949 09/983271 |
Document ID | / |
Family ID | 18800050 |
Filed Date | 2002-06-27 |
United States Patent
Application |
20020081949 |
Kind Code |
A1 |
Yoshida, Hiroyuki ; et
al. |
June 27, 2002 |
Polishing composition
Abstract
A polishing composition comprising an improver of a ratio of a
polishing rate of an insulating film to that of a stopper film,
wherein the polishing rate of the stopper film is selectively
decreased, comprising one or more compounds selected from the group
consisting of a monoamine or diamine compound; a polyamine having
three or more amino groups in its molecule; an ether
group-containing amine; and a heterocyclic compound having nitrogen
atom. The polishing composition can be used for removing an
insulating film which has been embedded for isolation into a trench
formed on a silicon substrate and sedimented outside the trench,
thereby planing a surface of the silicon substrate.
Inventors: |
Yoshida, Hiroyuki;
(Wakayama-shi, JP) ; Hagihara, Toshiya;
(Wakayama-shi, JP) ; Hashimoto, Ryoichi;
(Wakayama-shi, JP) ; Yoneda, Yasuhiro;
(Wakayama-shi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
18800050 |
Appl. No.: |
09/983271 |
Filed: |
October 23, 2001 |
Current U.S.
Class: |
451/41 ;
257/E21.244 |
Current CPC
Class: |
C09G 1/02 20130101; C09K
3/1463 20130101; H01L 21/31053 20130101 |
Class at
Publication: |
451/41 |
International
Class: |
B24B 007/22 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 23, 2000 |
JP |
2000-322123 |
Claims
What is claimed is:
1. An improver of a ratio of a polishing rate of an insulating film
to that of a stopper film, wherein the polishing rate of the
stopper film is selectively decreased, comprising one or more
compounds selected from the group consisting of: (A) a monoamine
compound represented by Formula (I): 12 wherein each of R.sup.1,
R.sup.2 and R.sup.3 is independently hydrogen atom, an alkyl group
having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon
atoms, with proviso that a total number of carbon atoms in R.sup.1,
R.sup.2 and R.sup.3 is from 1 to 8; (B) a diamine compound
represented by Formula (II): 13 wherein each of R.sup.4, R.sup.5,
R.sup.7 and R.sup.8 is independently hydrogen atom, an alkyl group
having 1 to 6 carbon atoms or an alkanol group having 1 to 6 carbon
atoms; and R.sup.6 is a linear, branched or cyclic alkylene group
having 1 to 18 carbon atoms, or a group represented by Formula
(III): 14 wherein each of R.sup.9 and R.sup.10 is independently
hydrogen atom or an alkyl group having 1 to 6 carbon atoms; and
each of a and b is an integer of from 0 to 9, with proviso that a
total number of carbon atoms in Formula (III) is from 2 to 18; (C)
a monoamine compound represented by Formula (IV): 15 wherein each
of R.sup.11, R.sup.12 and R.sup.13 is independently hydrogen atom,
an alkyl group having 1 to 8 carbon atoms, an alkanol group having
1 to 8 carbon atoms, an alkanediol group having 1 to 8 carbon
atoms, an alkanetriol group having 1 to 8 carbon atoms or a group
represented by --(R.sup.14O).sub.cR.sup.15; R.sup.14 is an alkylene
group having 1 to 4 carbon atoms; R.sup.15 is hydrogen atom, an
alkyl group having 1 to 18 carbon atoms or an acyl group having 1
to 18 carbon atoms; and c is an integer of from 1 to 20, with
proviso that: (i) at least one of R.sup.11, R.sup.12 and R.sup.13
is an alkanediol group having 1 to 8 carbon atoms, an alkanetriol
group having 1 to 8 carbon atoms or a group represented by
--(R.sup.14O).sub.cR.sup.35, wherein R.sup.35 is an alkyl group
having 1 to 18 carbon atoms or an acyl group having 1 to 18 carbon
atoms; or (ii) in a case where at least one of R.sup.11, R.sup.12
and R.sup.13 is an alkanol group having 1 to 8 carbon atoms or a
group represented by --(R.sup.14O).sub.cH, at least one of the
other groups is an alkyl group having 1 to 8 carbon atoms; (D) a
polyamine having three or more amino groups in its molecule; (E) an
ether group-containing amine; and (F) a heterocyclic compound
having nitrogen atom.
2. A polishing composition comprising the improver of claim 1.
3. The polishing composition according to claim 2, further
comprising an abrasive, a pH adjusting agent, or a mixture
thereof.
4. The polishing composition according to claim 2 or 3, which is
used for removing an insulating film which has been embedded for
isolation into a trench formed on a silicon substrate and
sedimented outside the trench, thereby planing a surface of the
silicon substrate.
5. A process for selectively increasing a ratio of a polishing rate
of an insulating film to that of a stopper film, comprising
applying the improver of claim 1.
6. A process for producing a substrate to be polished, comprising
applying the polishing composition of claim 2.
7. A process for producing a substrate to be polished, comprising
applying the polishing composition of claim 3.
8. A process for producing a substrate to be polished, comprising
applying the polishing composition of claim 4.
9. A polishing process comprising removing an insulating film which
has been embedded for isolation into a trench formed on a silicon
substrate and sedimented outside the trench with the polishing
composition of claim 2, thereby planing a surface of the silicon
substrate.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an improver of a ratio of a
polishing rate of an insulating film to that of a stopper film.
Further, the present invention relates to a polishing composition
comprising the improver, a process for selectively increasing a
ratio of a polishing rate of an insulating film to that of a
stopper film using the improver, and a process for producing a
substrate to be polished using the above-mentioned polishing
composition.
[0003] 2. Discussion of the Related Art
[0004] Conventionally, isolation region has been formed by a
technique so-called LOCOS (Local Oxidation of Silicon) method.
However, the LOCOS method does not meet the requirement for
high-integration of the semiconductor of the recent year because an
effective isolation region is narrowed in the LOCOS method.
Therefore, recently, there has been employed a so-called STI
(Shallow Trench Isolation) method comprising depositing a stopper
film such as a silicon nitride film on a silicon substrate,
embedding an insulating film such as a silicon oxide film in a
trench part, planing an excessive insulating film in the external
part of the trench by using chemical-mechanical polishing (CMP) to
expose the stopper film, and thereafter removing the stopper film
by etching. In the STI method, it is desired that a ratio of the
polishing rate of the insulating film to that of the stopper film
is increased in order to prevent dishing or thinning generated
during polishing of the insulating film on a substrate to be
polished, thereby achieving planarization of the insulating
film.
[0005] Presently, a ceria polishing agent used as a polishing agent
for STI-CMP exhibits a high polishing rate of an insulating film,
and selectively controls a polishing rate of a stopper film,
thereby achieving efficient planarization. However, as compared to
a silica polishing agent, there arise some problems such that the
ceria polishing agent is high in costs, and abrasive grains are not
easily dispersed therein. On the other hand, a commercially
available polishing agent has a low ratio of a polishing rate of an
insulating film to that of a stopper film. Therefore, there arise a
problem such that polishing is undesirably progressed at parts
where trench portions are closely arranged, as compared to parts
where there are fewer trench portions, so that thinning is likely
to be generated. In addition, when a stopper film is made thicker
in order to prevent thinning, there arise a problem such that an
insulating film in the trench part remains in a large amount by
removal of the stopper film after CMP, so that there is still yet a
great difference in the levels (step height) between a silicon
substrate surface and an insulating film surface.
[0006] There have been reported that a ratio of polishing rates can
be increased by adding triethanolamine as disclosed in Japanese
Patent Laid-Open No. Hei 11-330025, or adding tetramethylammonium
hydroxide and hydrogen peroxide as disclosed in Japanese Patent
Laid-Open No. Hei 10-270401. However, in the former method, there
arise some problems such that addition of a large amount of
triethanolamine so as to have a concentration of 10% by weight or
more is needed in order to exhibit its effects, thereby increasing
its costs including costs for waste water treatment. In the latter
method, hydrogen peroxide is likely to be decomposed, so that its
effects, including stability, are not sufficient.
[0007] An object of the present invention is to provide an improver
of a ratio of a polishing rate of an insulating film to that of a
stopper film for stably and selectively increasing the ratio of a
polishing rate of an insulating film to that of a stopper film.
[0008] Another object of the present invention is to provide a
polishing composition comprising the improver, a process for
selectively increasing a ratio of a polishing rate of an insulating
film to that of a stopper film, and a process for producing a
substrate to be polished using the above-mentioned polishing
composition.
[0009] These and other objects of the present invention will be
apparent from the following description.
SUMMARY OF THE INVENTION
[0010] According to the present invention, there are provided:
[0011] [1] an improver of a ratio of a polishing rate of an
insulating film to that of a stopper film, wherein the polishing
rate of the stopper film is selectively decreased, comprising one
or more compounds selected from the group consisting of:
[0012] (A) a monoamine compound represented by Formula (I): 1
[0013] wherein each of R.sup.1, R.sup.2 and R.sup.3 is
independently hydrogen atom, an alkyl group having 1 to 6 carbon
atoms or an alkenyl group having 2 to 6 carbon atoms, with proviso
that a total number of carbon atoms in R.sup.1, R.sup.2 and R.sup.3
is from 1 to 8;
[0014] (B) a diamine compound represented by Formula (II): 2
[0015] wherein each of R.sup.4, R.sup.5, R.sup.7 and, R.sup.8 is
independently hydrogen atom, an alkyl group having 1 to 6 carbon
atoms or an alkanol group having 1 to 6 carbon atoms; and R.sup.6
is a linear, branched or cyclic alkylene group having 1 to 18
carbon atoms, or a group represented by Formula (III): 3
[0016] wherein each of R.sup.9 and R.sup.10 is independently
hydrogen atom or an alkyl group having 1 to 6 carbon atoms; and
each of a and b is an integer of from 0 to 9, with proviso that a
total number of carbon atoms in Formula (III) is from 2 to 18;
[0017] (C) a monoamine compound represented by Formula (IV): 4
[0018] wherein each of R.sup.11, R.sup.12 and R.sup.13 is
independently hydrogen atom, an alkyl group having 1 to 8 carbon
atoms, an alkanol group having 1 to 8 carbon atoms, an alkanediol
group having 1 to 8 carbon atoms, an alkanetriol group having 1 to
8 carbon atoms or a group represented by
--(R.sup.14O).sub.cR.sup.15; R.sup.14 is an alkylene group having 1
to 4 carbon atoms; R.sup.15 is hydrogen atom, an alkyl group having
1 to 18 carbon atoms or an acyl group having 1 to 18 carbon atoms;
and c is an integer of from 1 to 20, with proviso that:
[0019] (i) at least one of R.sup.11, R.sup.12 and R.sup.13 is an
alkanediol group having 1 to 8 carbon atoms, an alkanetriol group
having 1 to 8 carbon atoms or a group represented by
--(R.sup.14O).sub.cR.sup.35- , wherein R.sup.35 is an alkyl group
having 1 to 18 carbon atoms or an acyl group having 1 to 18 carbon
atoms; or
[0020] (ii) in a case where at least one of R.sup.11, R.sup.12 and
R.sup.13 is an alkanol group having 1 to 8 carbon atoms or a group
represented by --(R.sup.14O).sub.cH, at least one of the other
groups is an alkyl group having 1 to 8 carbon atoms;
[0021] (D) a polyamine having three or more amino groups in its
molecule;
[0022] (E) an ether group-containing amine; and
[0023] (F) a heterocyclic compound having nitrogen atom;
[0024] [2] a polishing composition comprising the improver of item
[1] above;
[0025] [3] a process for selectively increasing a ratio of a
polishing rate of an insulating film to that of a stopper film,
comprising applying the improver of item [1] above;
[0026] [4] a process for producing a substrate to be polished,
comprising applying the polishing composition of item [2] above;
and
[0027] [5] a polishing process comprising removing an insulating
film which has been embedded for isolation into a trench formed on
a silicon substrate and sedimented outside the trench with the
polishing composition of item [2] above, thereby planing a surface
of the silicon substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1 is a schematic view showing a carrier surface used in
Examples.
DETAILED DESCRIPTION OF THE INVENTION
[0029] In the present invention, the phrase "a ratio of a polishing
rate of an insulating film to that of a stopper film, wherein the
polishing rate of the stopper film is selectively decreased" is
hereinafter also referred to as `selective ratio.` Therefore, the
term "improver of a ratio of a polishing rate of an insulating film
to that of a stopper film" (hereinafter also referred to as
"improver of a selective ratio") refers to an agent having an
action of increasing a ratio of a polishing rate of an insulating
film to that of a stopper film in STI method by containing the
improver of a selective ratio in the polishing composition,
concretely, having an action of reducing the polishing rate of a
stopper film without remarkably lowering the polishing rate of the
insulating film. Here, as to the ratio of polishing rates to be
increased by the improver of a selective ratio, i.e. (polishing
rate of insulating film)/(polishing rate of stopper film), the
improver of a selective ratio preferably has a selective ratio
exceeding 3 to 4 that of the commercially available silica
polishing agent, from the viewpoint of facilitating the detection
of the end point of polishing (viewpoint of being capable of easily
stopping polishing at a given position), and the viewpoint of
planing a substrate to be polished after polishing. The selective
ratio is preferably 6 or more, more preferably 8 or more, still
more preferably 10 or more, especially preferably 15 or more. The
polishing rate of each film is that determined by the method
described in Examples set forth below.
[0030] The improver of a selective ratio of the present invention
comprises, as described above, one or more compounds selected from
the group consisting of:
[0031] (A) a monoamine compound represented by Formula (I): 5
[0032] wherein each of R.sup.1, R.sup.2 and R.sup.3 is
independently hydrogen atom, an alkyl group having 1 to 6 carbon
atoms or an alkenyl group having 2 to 6 carbon atoms, with proviso
that a total number of carbon atoms in R.sup.1, R.sup.2 and R.sup.3
is from 1 to 8;
[0033] (B) a diamine compound represented by Formula (II): 6
[0034] wherein each of R.sup.4, R.sup.5, R.sup.7 and R.sup.8 is
independently hydrogen atom, an alkyl group having 1 to 6 carbon
atoms or an alkanol group having 1 to 6 carbon atoms; and R.sup.6
is a linear, branched or cyclic alkylene group having 1 to 18
carbon atoms, or a group represented by Formula (III): 7
[0035] wherein each of R.sup.9 and R.sup.10 is independently
hydrogen atom or an alkyl group having 1 to 6 carbon atoms; and
each of a and b is an integer of from 0 to 9, with proviso that a
total number of carbon atoms in Formula (III) is from 2 to 18;
[0036] (C) a monoamine compound represented by Formula (IV): 8
[0037] wherein each of R.sup.11, R.sup.12 and R.sup.13 is
independently hydrogen atom, an alkyl group having 1 to 8 carbon
atoms, an alkanol group having 1 to 8 carbon atoms, an alkanediol
group having 1 to 8 carbon atoms, an alkanetriol group having 1 to
8 carbon atoms or a group represented by
--(R.sup.14O).sub.cR.sup.15; R.sup.14 is an alkylene group having 1
to 4 carbon atoms; R.sup.15 is hydrogen atom, an alkyl group having
1 to 18 carbon atoms or an acyl group having 1 to 18 carbon atoms;
and c is an integer of from 1 to 20, with proviso that:
[0038] (i) at least one of R.sup.11, R.sup.12 and R.sup.13 is an
alkanediol group having 1 to 8 carbon atoms, an alkanetriol group
having 1 to 8 carbon atoms or a group represented by
--(R.sup.14O).sub.cR.sup.35- , wherein R.sup.35 is an alkyl group
having 1 to 18 carbon atoms or an acyl group having 1 to 18 carbon
atoms; or
[0039] (ii) in a case where at least one of R.sup.11, R.sup.12 and
R.sup.13 is an alkanol group having 1 to 8 carbon atoms or a group
represented by --(R.sup.14O).sub.cH, at least one of the other
groups is an alkyl group having 1 to 8 carbon atoms;
[0040] (D) a polyamine having three or more amino groups in its
molecule;
[0041] (E) an ether group-containing amine; and
[0042] (F) a heterocyclic compound having nitrogen atom.
[0043] In Formula (I), each of R.sup.1, R.sup.2 and R.sup.3 is
hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an
alkenyl group having 2 to 6 carbon atoms. Each of R.sup.1, R.sup.2
and R.sup.3 is an alkyl group having preferably 1 to 4 carbon
atoms, more preferably 1 to 3 carbon atoms, from the viewpoint of
increase in the selective ratio. In addition, the total number of
carbon atoms in R.sup.1, R.sup.2 and R.sup.3 is preferably from 1
to 6, more preferably from 1 to 4, still more preferably from 1 to
3, from the viewpoint of the increase in the selective ratio. In
addition, primary amines and secondary amines are preferable, and
the primary amines are more preferable, from the viewpoint of the
increase in the selective ratio. Further, the alkyl groups may have
a linear structure, a branched structure or a cyclic structure, and
a linear structure or a branched structure is preferable.
[0044] Concrete examples of the monoamine compound represented by
Formula (1) include methylamine, ethylamine, propylamine,
isopropylamine, butylamine, isobutylamine, sec-butylamine,
pentylamine, hexylamine, dimethylamine, diethylamine,
dipropylamine, diisopropylamine, methylethylamine, trimethylamine,
triethylamine, allylamine, diallylamine, N,N-dimethylallylamine,
N-methyldiallylamine, cyclopropylamine, cyclobutylamine,
cyclopentylamine, cyclohexylamine, and the like. Methylamine,
ethylamine, propylamine, isopropylamine, dimethylamine,
diethylamine, dipropylamine and diisopropylamine are preferable,
from the viewpoint of the increase in the selective ratio.
Particularly preferable are propylamine and isopropylamine. These
amine compounds may be used alone or in admixture of two or more
kinds.
[0045] In Formula (II), each of R.sup.4, R.sup.5, R.sup.7 and
R.sup.8 is hydrogen atom, an alkyl group having 1 to 6 carbon atoms
or an alkanol group having 1 to 6 carbon atoms. Each of R.sup.4,
R.sup.5, R.sup.7 and R.sup.8 is preferably hydrogen atom, an alkyl
group having 1 to 4 carbon atoms or an alkanol group having 1 to 4
carbon atoms, more preferably hydrogen atom, an alkyl group having
1 to 3 carbon atoms or an alkanol group having 1 to 3 carbon atoms,
wherein the alkyl group or the alkanol group may have a linear
structure or a branched structure, from the viewpoint of the
solubility in water and the viewpoint of the increase in the
selective ratio, in addition, R.sup.6 is a linear, branched or
cyclic alkylene group having 1 to 18 carbon atoms, or a group
represented by Formula (III). Among them, the group represented by
Formula (III) is preferable, from the viewpoint of the increase in
the selective ratio.
[0046] Each of R.sup.9 and R.sup.10 is hydrogen atom or an alkyl
group having 1 to 6 carbon atoms. Each of R.sup.9 and R.sup.10 is
preferably hydrogen atom or an alkyl group having 1 to 4 carbon
atoms, more preferably hydrogen atom or an alkyl group having 1 to
3 carbon atoms, from the viewpoint of the solubility in water and
the viewpoint of the increase in the selective ratio,. In addition,
each of a and b is an integer of from 0 to 9. Each of a and b is an
integer of preferably from 0 to 8, more preferably from 0 to 5,
especially preferably from 0 to 3, from the viewpoint of the
solubility in water and the viewpoint of the increase in the
selective ratio. In addition, a +b is preferably from 1 to 11, more
preferably from 1 to 9, still more preferably from 1 to 7,
especially preferably from 1 to 5. Further, the total number of
carbon atoms in Formula (III) is from 2 to 18, preferably from 2 to
16, more preferably from 2 to 12, especially preferably from 2 to
10, from the viewpoint of the increase in the selective ratio.
[0047] Concrete examples of the diamine compound represented by
Formula (II) include ethylenediamine, 1,2-diaminopropane,
1,3-propanediamine, 1,4-butanediamine, N,N-dimethylethylenediamine,
N,N'-dimethylethylenediam- ine, N-ethylethylenediamine,
N-methyl-1,3-propanediamine, pentamethylenediamine,
1,3-diaminopentane, N-isopropylethylenediamine,
hexamethylenediamine, N-isopropyl-1,3-propanediamine,
N,N,N',N'-tetramethylethylenediamine, heptamethylenediamine,
N,N,N',N'-tetramethyl-1,2-propanediamine,
N,N,N',N'-tetramethyl-1,3-propa- nediamine,
N,N,2,2-tetramethyl-1,3-propanediamine, octamethylenediamine,
N,N'-dimethyl-1,6-diaminohexane,
N,N,N',N'-tetramethyl-1,4-butanediamine, nonamethylenediamine,
N,N,N',N'-tetramethyl-2,2-dimethyl-1,3-propanediami- ne,
decamethylenediamine, N,N,N',N'-tetramethyl-1,6-diaminohexane,
undecamethylenediamine, 3-(dibutylamino)propylamine,
dodecamethylenediamine, cyclohexanediamine,
2-hydroxyethylaminopropylamin- e, diethanolaminopropylamine, and
the like.
[0048] Among them, ethylenediamine, 1,2-diaminopropane,
1,3-propanediamine, 1,4-butanediamine, hexamethylenediamine and
N,N,N',N'-tetramethyl-1,6-diaminohexane are preferable, from the
viewpoint of the solubility in water and the viewpoint of the
increase in the selective ratio.
N,N,N',N'-tetramethyl-1,6-diaminohexane are especially preferable.
These amine compounds may be used alone or in admixture of two or
more kinds.
[0049] In Formula (IV), each of R.sup.11, R.sup.12 and R.sup.13 is
hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an
alkanol group having 1 to 8 carbon atoms, an alkanediol group
having 1 to 8 carbon atoms, an alkanetriol group having 1 to 8
carbon atoms or a group represented by
.about.(R.sup.14O).sub.cR.sup.15. Here, R.sup.14 is an alkylene
group having 1 to 4 carbon atoms. R.sup.14 is an alkylene group
having preferably 2 or 3 carbon atoms, from the viewpoint of the
solubility in water. R.sup.15 is hydrogen atom, an alkyl group
having 1 to 18 carbon atoms or an acyl group having 1 to 18 carbon
atoms. R.sup.15 is preferably hydrogen atom or an alkyl group
having 1 to 12 carbon atoms, more preferably hydrogen atom or an
alkyl group having 1 to 6 carbon atoms, still more preferably
hydrogen atom or an alkyl group having 1 to 4 carbon atoms, from
the viewpoints of the increase in the selective ratio and the
stability. In addition, c is an integer of from 1 to 20. c is an
integer of preferably from 1 to 10, more preferably from 1 to 8,
especially preferably from 1 to 5, from the viewpoint of the
increase in the selective ratio. In addition, as to the number of
carbon atoms in the alkyl group, the alkanol group, the alkanediol
group or the alkanetriol group for R.sup.11 to R.sup.13, the number
of carbon atoms in the alkyl group is preferably from 1 to 6, more
preferably from 1 to 4, especially preferably from 1 to 3, from the
viewpoint of the increase in the selective ratio. The alkyl chain
may have a linear structure or a branched structure. In addition,
the number of carbon atoms in each of the alkanol group, the
alkanediol group or the alkanetriol group is preferably from 2 to
8, more preferably from 3 to 6. Here, at least one of R.sup.11,
R.sup.12 and R.sup.13 is an alkanediol group having 1 to 8 carbon
atoms, an alkanetriol group having 1 to 8 carbon atoms or a group
represented by .about.(R.sup.14O).sub.cR.sup.35, wherein R.sup.35
is an alkyl group having 1 to 18 carbon atoms or an acyl group
having 1 to 18 carbon atoms. Alternatively, in a case where at
least one of R.sup.11, R.sup.12 and R.sup.13 is an alkanol group
having 1 to 8 carbon atoms or a group represented by
--(R.sup.14O).sub.cH, at least one of the other groups is an alkyl
group having 1 to 8 carbon atoms. In the case where two of
R.sup.11, R.sup.12 and R.sup.13 are a group represented by
--(R.sup.14O).sub.cR.sup.15, each of R.sup.14, R.sup.15 and c in
each group may be identical or different.
[0050] Concrete examples of the monoamine compound represented by
Formula (IV) include 2-(methylamino)ethanol, N-ethyldiethanolamine,
3-(methylamino)propanol, N-methyldipropanolamine,
2-(ethylamino)ethanol, 2-(dimethylamino)ethanol,
4-(methylamino)dibutanol, 2-(isopropylamino)ethanol,
1-(dimethylamino)-2-propanol, 4-(dimethylamino)-1-butanol,
4-(ethylamino)-1-butanol, 3-(diethylamino)-1-propanol,
1-(diethylamino)-2-propanol, 6-(dimethylamino)-1-hexanol,
2-(diisopropylamino)ethanol, 2-(dibutylamino)ethanol,
N,N-dimethylethoxyethanolamine,
N,N-dimethylethoxyethoxyethanolamine,
N,N-diethylethoxyethanolamine, N,N-diethylethoxyethoxyethanolamine,
2-amino-1,3-propanediol, 3-amino-1,2-propanediol,
2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol,
3-diethylamino-1,2-propanediol, 3-dimethylamino-1,2-propanediol,
3-methylamino-1,2-propanediol, tris(hydroxymethyl)aminomethane,
ethoxypropylamine, 3-methoxypropylamine, 2-methoxyethylamine,
3-propoxypropylamine, 3-isobutoxypropylamine,
bis(2-methoxyethyl)amine, and the like. Among them,
6-(dimethylamino)-1-hexanol is especially preferable, from the
viewpoint of the increase in the selective ratio. These amine
compounds may be used alone or in admixture of two or more
kinds.
[0051] The polyamine having three or more amino groups in its
molecule includes a compound represented by Formula (V): 9
[0052] wherein each of R.sup.16, R.sup.17, R.sup.21, R.sup.23 and
R.sup.24 is independently hydrogen atom or an alkyl group having 1
to 6 carbon atoms; each of R.sup.18, R.sup.20 and R.sup.22 is
independently an alkylene group having 1 to 18 carbon atoms; and
R.sup.19 is hydrogen atom, an alkyl group having 1 to 6 carbon
atoms or a group represented by Formula (VI): 10
[0053] wherein R.sup.25 is an alkylene group having 1 to 18 carbon
atoms; and each of R.sup.26 and R.sup.27 is independently hydrogen
atom or an alkyl group having 1 to 6 carbon atoms; and
[0054] d is an integer of from 0 to 20, and
[0055] an amino group-containing polymer compound.
[0056] Here, each of R.sup.16, R.sup.17, R.sup.21, R.sup.23,
R.sup.24, R.sup.26 and R.sup.27 is hydrogen atom or an alkyl group
having 1 to 6 carbon atoms. Each of R.sup.16, R.sup.17, R.sup.21,
R.sup.23, R.sup.24, R.sup.26 and R.sup.27 is preferably hydrogen
atom or an alkyl group having 1 to 3 carbon atoms, from the
viewpoint of the increase in the selective ratio. In addition, each
of R.sup.18, R.sup.20, R.sup.22 and R.sup.25 is an alkylene group
having 1 to 18 carbon atoms. Each of R.sup.18, R.sup.20, R.sup.22
and R.sup.25 is an alkylene group having preferably 2 to 12 carbon
atoms, more preferably 2 to 6 carbon atoms, from the viewpoint of
the increase in the selective ratio. In addition, d is an integer
of from 0 to 20. d is preferably from 0 to 6, more preferably from
0 to 4, still more preferably from 0 to 1, from the viewpoint of
the increase in the selective ratio. Incidentally, in a case where
d is 2 or more, plural R.sup.20 and plural R.sup.21 groups may
respectively be identical to or different from each other.
[0057] Concrete examples of the polyamine having three or more
amino groups in its molecule include diethylenetriamine,
bis(3-aminopropyl)amine, N-methyl-3,3'-iminobis(propylamine),
bis(hexamethylene)triamine, spermidine, spermine,
triethylenetetramine, N,N'-bis(2-aminopropyl)ethylenediamine,
N,N'-bis(2-aminoethyl)-1,3-propan- ediamine,
N,N'-bis(3-aminopropyl)-1,3-propanediamine,
tris(2-aminoethyl)amine,
N,N,N',N',N"-pentamethyldiethylenetriamine, tetraethylenepentamine,
polyethyleneimine, polyvinylamine, and the like. Among them,
bis(3-aminopropyl)amine and triethylenetetramine are preferable,
from the viewpoint of the increase in the selective ratio. These
polyamines having three or more amino groups in their molecules may
be used alone or in admixture of two or more kinds.
[0058] The ether group-containing amine includes a compound
represented by 11
[0059] wherein each of R.sup.28, R.sup.29, R.sup.33 and R.sup.34 is
independently hydrogen atom or an alkyl group having 1 to 6 carbon
atoms; each of R.sup.30 and R.sup.32 is independently an alkylene
group having 1 to 18 carbon atoms; R.sup.31 is an alkylene group
having 1 to 4 carbon atoms; and e is an integer of from 0 to
20.
[0060] Here, each of R.sup.28, R.sup.29, R.sup.33 and R.sup.34 is
hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Each of
R.sup.28, R.sup.29, R.sup.33 and R.sup.34 is preferably hydrogen
atom or an alkyl group having 1 to 3 carbon atoms, from the
viewpoint of the increase in the selective ratio. Each of R.sup.30
and R.sup.32 is an alkylene group having 1 to 18 carbon atoms. Each
of R.sup.30 and R.sup.32 is an alkylene group having preferably 2
to 12 carbon atoms, more preferably 2 to 6 carbon atoms, from the
viewpoint of the increase in the selective ratio. In addition, e is
an integer of from 0 to 20. e is preferably from 0 to 10, more
preferably from 0 to 8, still more preferably from 0 to 5, from the
viewpoint of the increase in the selective ratio. In the case where
e is 2 or more, plural R.sup.30 may be identical to or different
with each other.
[0061] Concrete examples of the ether group-containing amine
include bis(3-aminopropyl) ether, dimethylaminoethoxypropylamine,
1,2-bis(2-aminoethoxy)ethane, 1,2-bis(3-aminopropoxy)ethane,
4,9-dioxa-1,12-dodecanediamine, diethylene glycol
bis(3-aminopropyl) ether, and the like. Among them, diethylene
glycol bis(3-aminopropyl) ether is preferable, from the viewpoint
of the increase in the selective ratio. These ether
group-containing amines may be used alone or in admixture of two or
more kinds.
[0062] Various compounds may be used as the heterocyclic compound
having nitrogen atom, and heterocyclic compounds in which one or
more nitrogen atoms constituting the heterocyclic ring are
secondary amines are preferable, from the viewpoint of the increase
in the selective ratio.
[0063] Concrete examples of the heterocyclic compound having
nitrogen atom include piperidine, piperazine, homopiperazine,
pyrrolidine, pyridine, pyrazine, pyrrole, triethylenediamine,
morpholine, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine,
3-amino-1,2,4-triazole, N-(3-aminopropyl)morpholine,
N-(2-aminoethyl)morpholine, N-aminoethylpiperidine,
N-aminopropylpiperidine, 1-amino-4-methylpiperazi- ne,
2-methylimidazole, 4-methylimidazole, 1,3-di(4-piperidyl)propane,
2,6-dimethylpiperazine, 2,5-dimethylpiperazine,
3,5-dimethylpyrazole, bis(3-aminopropyl)piperazine,
aminoethylpiperazine, hydroxyethylpiperazine, pipecoline,
2-(1-piperazinyl)pyrimidine, 4-piperidinopyridine,
pyridinemethanol, N-methylpiperazine, 2-methylpiperazine,
N-methylpiperidine, 3-piperidinemethanol, 4-hydroxypiperidine, and
the like. Among them, piperazine and piperidine are preferable,
from the viewpoint of the increase in the selective ratio. These
heterocyclic compounds having nitrogen atom may be used alone or in
admixture of two or more kinds.
[0064] Further, the monoamine compound represented by Formula (I),
the diamine compound represented by Formula (II), the monoamine
compound represented by Formula (IV), the polyamine having three or
more amino groups in its molecule, the ether group-containing amine
and the heterocyclic compounds having nitrogen atom may be used in
admixture of two or more kinds.
[0065] In the present invention, by using the above-mentioned
improver of a selective ratio in a polishing composition, there is
exhibited an excellent effect that the selective ratio of a
polishing rate of an insulating film to that of a stopper film can
be increased stably and in a low cost in the polishing according to
the STI method. The reason why the above-mentioned effect is
exhibited is presumably due to the fact that the above-mentioned
improver of a selective ratio is selectively adsorbed on the
stopper film surface, thereby controlling the polishing rate of the
stopper film.
[0066] Accordingly, the present invention provides a process for
selectively increasing a selective ratio of a polishing rate of an
insulating film to that of a stopper film using the above-mentioned
improver of a selective ratio.
[0067] The polishing composition of the present invention comprises
the above-mentioned improver of a selective ratio. The amount of
the improver of a selective ratio is preferably from 0.01 to 20% by
weight, more preferably from 0.1 to 15% by weight, still more
preferably from 0.3 to 10% by weight, most preferably from 0.5 to
5% by weight, of the entire amount of the polishing composition,
from the viewpoint of selectively controlling the polishing rate of
the stopper film without drastically reducing the polishing rate of
the insulating film and the viewpoint of the surface properties of
the substrate after polishing.
[0068] It is preferable that the polishing composition of the
present invention further comprises a pH adjusting agent and/or an
abrasive.
[0069] The pH of the polishing composition is preferably from 8 to
13, more preferably from 10 to 13, from the viewpoint of showing a
high polishing rate of the insulating film. A pH adjusting agent is
used in order to adjust the pH in such a manner.
[0070] As the pH adjusting agent, an alkaline source such as
ammonia (concretely an aqueous ammonia), potassium hydroxide or an
amine can be appropriately used. Incidentally, since the
above-mentioned improver of a selective ratio has a pH adjusting
ability, when this improver of a selective ratio is used, the use
of the above-mentioned alkali source can be omitted, or the amount
of the alkali source used can be reduced. In addition, the content
of the pH adjusting agent is preferably from 0.001 to 5% by weight,
more preferably from 0.01 to 3% by weight, still more preferably
from 0.1 to 1% by weight, of the entire amount of the polishing
composition, from the viewpoint of the increase in the selective
ratio.
[0071] As the abrasive used in the present invention, any abrasives
generally employed for polishing can be used. Examples of the
abrasive include metals: carbides of metals or metalloids, nitrides
of metals or metalloids, oxides of metals or metalloids, borides of
metals or metalloids; diamond, and the like. The metals or
metalloids include those elements belonging to the Groups 2A, 2B,
3A, 3B, 4A, 4B, 5A, 6A, 7A or 8 of the Periodic Table (long period
form). Concrete examples of the abrasive include a-alumina
particles, silicon carbide particles, diamond particles, magnesium
oxide particles, zinc oxide particles, cerium oxide particles,
zirconium oxide particles, colloidal silica particles, fumed silica
particles, and the like. Among them, silica is preferable, from the
viewpoints of giving excellent dispersibility of the abrasive and
surface properties of the substrate after polishing. More
preferable are the colloidal silica prepared by a process using an
alkali silicate or an alkoxysilane as a starting raw material; and
fumed silica prepared by high-temperature hydrolysis of a volatile
silicon compound such as silicon tetrachloride in oxyhydrogen
flame. The average particle size of the abrasive, as calculated
from the specific surface area determined by the BET method, is
preferably from 1 to 1000 nm, more preferably from 5 to 500 nm,
still more preferably from 10 to 300 nm, from the viewpoint of
increasing the polishing rate. The amount of the abrasive is
preferably from 0.5 to 30% by weight, more preferably from 1 to 25%
by weight, still more preferably from 3 to 15% by weight, of the
entire amount of the polishing composition, from the viewpoint of
increasing the polishing rate.
[0072] The polishing composition of the present invention, which
comprises the improver of a selective ratio, or the improver of a
selective ratio and a pH adjusting agent, is effective for a
polishing process using a fixed grinding wheel, a polishing pad in
which the abrasive grains are fixed in the pad, and the like.
Further, the polishing composition comprising the above-mentioned
abrasive is effective for a polishing process employing loose
abrasives using a polishing pad made of polyurethane, and the
polishing composition is also effective for a polishing process
using a fixed grinding wheel, a polishing pad in which the abrasive
grains are fixed in the pad, and the like.
[0073] The balance of the polishing composition of the present
invention is water. The water content is preferably from 45 to
99.49% by weight, more preferably from 55 to 99% by weight, still
more preferably from 65 to 95% by weight, of the entire amount of
the polishing composition, from the viewpoint of the increase in
the selective ratio.
[0074] In addition, the polishing composition of the present
invention can optionally comprise other component including a
disinfectant and an antibacterial agent, such as
tetramethylammonium chloride, tetraethylammonium chloride,
tetramethylammonium hydroxide, tetraethylammonium hydroxide,
benzalkonium chloride, and benzethonium chloride.
[0075] The concentration of each of the components in the
above-mentioned polishing composition is a preferable concentration
during polishing, and the concentration may be that at the time the
composition is prepared. The polishing composition may be prepared
as a concentrate, and used by dilution upon use.
[0076] By using the polishing composition of the present invention
having the above-mentioned constitution, there is exhibited an
excellent effect that a substrate to be polished having an
extremely small difference between the level of a silicon substrate
surface after removing the stopper film and the level of the
insulating film surface on the trench part can be obtained stably
and at a low cost, in the polishing according to the STI
method.
[0077] The polishing composition of the present invention is
suitably used in, for instance, the STI method comprising removing
an insulating film which has been embedded for isolation into a
trench formed on a silicon substrate and sedimented outside the
trench, thereby planing a surface of the silicon substrate.
[0078] In addition, the process for producing a substrate to be
polished of the present invention is carried out by using the
polishing composition of the present invention. Here, by polishing
with the polishing composition comprising the improver of a
selective ratio of the present invention, the selective ratio of a
polishing rate of an insulating film to that of a stopper film is
increased, so that an excellent planarization can be carried out.
In addition, the thickness of the stopper film such as a silicon
nitride film can be reduced without causing a defect such as
thinning in a substrate to be polished due to the planarization, so
that high integration of semiconductors can be attained.
[0079] The substrate to be polished used in the present invention
is a substrate which is obtained by an isolation step comprising
embedding an insulating film in a trench formed on a silicon
substrate, such as the STI method. The substrate to be polished
comprises an insulating film, which is an object to be polished,
and a stopper film for controlling the progress of polishing.
[0080] The insulating film used in the present invention is
preferably a silicon oxide film, among which a plasma TEOS film, an
atmospheric CVD film, a thermal oxidation film and the like can be
used. On the other hand, the stopper film is preferably a silicon
nitride film, among which a low pressure CVD film, an atmospheric
CVD film and the like can be used. The properties, such as
thickness, of the insulating film and the stopper film are not
particularly limited.
[0081] In the process for producing a substrate to be polished of
the present invention, in order to remove an excess insulating film
formed on the silicon substrate during an isolation step comprising
embedding an insulating film in a trench formed on a silicon
substrate, such as the STI method, a planed, substrate to be
polished can be efficiently prepared by polishing with the
polishing composition comprising the improver of a selective
ratio.
EXAMPLES
[0082] The expression "% by weight" in Examples is made on the
basis of the entire weight of the polishing composition. As the
polishing device, a single-sided polishing machine (product number:
MA-300, manufactured by Engis Corporation) was used. The polishing
conditions are given below.
[0083] 1) Polishing Conditions
[0084] In Examples, as a substrate to be polished, there were used
a silicon substrate (4 cm in length.times.4 cm in width) obtained
by vapor deposition of a silicon oxide film (oxide film serving as
an insulating film) on the substrate surface in a thickness of
10000.ANG. (1000 nm) by means of plasma TEOS, and a silicon
substrate (4 cm in length .times.4 cm in width) obtained by vapor
deposition of a silicon nitride film (nitride film serving as a
stopper film) on the substrate surface in a thickness of 3000.ANG.
(300 nm) by means of low pressure CVD.
[0085] As the polishing pad, there was used IC 1400(P) having an
outer diameter of 30 cm.PHI., manufactured by Rodel Nitta K. K.
Also, the polishing pressure was 2.5.times.10.sup.4 Pa, the flow
rate of the polishing agent was 50 mL/min. The disc rotational
speed was 80 rpm, and the number of rotations for polishing head
was 60 rpm, wherein the disc and the head were rotated in the same
rotation. The polishing time was 3 minutes. Further, a
water-sticking backing film was pasted on a supporting platform
made of a ceramic used for a polishing head, and a carrier 1 made
of a glass epoxy resin was pasted thereon. A substrate to be
polished 2 was adhered to the carrier 1 (see FIG. 1).
[0086] 2) Calculation of Polishing Rate
[0087] The polishing rate was determined by carrying out polishing
under the conditions mentioned above, determining an average value
of the change in the polishing film thickness of each substrate to
be polished before and after polishing, and dividing the resulting
average value by the polishing time. The amount of change in the
film thickness was calculated by obtaining a film thickness from an
ellipsometer (MARY-102LD, manufactured by Five Lab K. K.).
[0088] 3) Calculation of Selective Ratio of Polishing Rate
[0089] The selective ratio of a polishing rate was calculated by
dividing the polishing rate of the oxide film by the polishing rate
of the nitride film.
EXAMPLES 1 to 11 AND COMPARATIVE EXAMPLES 1 to 5
[0090] A commercially available silica polishing agent (trade name
"Semi Sperse 25," manufactured by Cabot Corporation, containing
potassium hydroxide as a pH adjusting agent) was well shaken before
use. After having confirmed that there was no sedimentation of the
abrasive, 15 g of propylamine was added to 260 g of the polishing
agent, and ion-exchanged water was added to the mixture to make up
a total volume of 500 g (propylamine concentration: 3% by weight),
to give a polishing composition of Example 1. After stirring the
polishing composition, each of the oxide film and the nitride film
was polished under the above-mentioned polishing conditions The
polishing compositions of Examples 3 to 11 and Comparative Examples
1 to 5 were obtained by the same procedures as in Example 1, except
for using the improver of a selection ratio and the pH adjusting
agent shown in Table 1. Then, the same polishing procedures as in
Example 1 were carried out for Examples 3 to 11 and Comparative
Examples 1 to 5. As to Example 2, a commercially available silica
polishing agent ILD1300 (trade name, manufactured by Rodel Nitta K.
K.) was well shaken before use; having confining that there was no
sedimentation of silica therein, 5 g (concentration: 1% by weight)
of ethylenediamine was added to 495 g of the polishing agent, to
give a polishing composition. After stirring, each of the oxide
film and the nitride film was polished under the above-mentioned
polishing conditions. The results are shown in Table 1.
1TABLE 1 Polishing Rate Selective Improver of Selective Ratio
Classification (nm/minute) Ratio of Content of Improver of Oxide
Nitride Polishing pH Adjusting No. Kind (% by wt) Selective Ratio
Film Film Rates Agent pH Ex. 1 Propylamine 3.0 Formula (I) 204 13
16.0 Potassium Hydroxide 12.0 Ex. 2 Ethylenediamine 1.0 Formula
(II) 420 60 7.0 Ammonia 12.0 Ex. 3 Isopropylamine 3.0 Formula (I)
206 12 17.2 Potassium Hydroxide 12.0 Ex. 4 Diethylamine 3.0 Formula
(I) 160 30 5.3 Potassium Hydroxide 12.0 Ex. 5 Dipropylamine 3.0
Formula (I) 208 30 6.9 Potassium Hydroxide 12.0 Ex. 6 KL-1.sup.1)
1.0 Formula (II) 120 2 60.0 Potassium Hydroxide 12.0 Ex. 7
KL-25.sup.2) 5.0 Formula (IV) 196 8 24.5 Potassium Hydroxide 12.0
Ex. 8 Bis(3-aminopropyl)- 2.0 Formula (V) 154 18 8.4 Potassium
Hydroxide 12.0 amine Ex. 9 Triethylenetetramine 2.0 Formula (V) 163
13 13.0 Potassium Hydroxide 12.0 Ex. 10 Diethylene glycol 3.0
Formula (VII) 178 6 32.0 Potassium Hydroxide 12.0
bis(3-aminopropyl) Ether Ex. 11 Piperazine 5.0 Heterocyclic 199 7
29.6 Potassium Hydroxide 12.0 Compound Comp. -- -- -- 200 50 4.0
Potassium Hydroxide 11.0 Ex. 1 Comp. Triethanolamine 1.0 -- 140 46
3.0 Potassium Hydroxide 12.0 Ex. 2 Comp. Triethanolamine 3.0 -- 124
45 2.8 Potassium Hydroxide 12.0 Ex. 3 Comp. Triethanolamine 5.0 --
110 46 2.4 Potassium Hydroxide 12.0 Ex. 4 Comp. TMAH.sup.3) 3.0 --
40 10 4.0 Potassium Hydroxide 12.0 Ex. 5 .sup.1.sup.)Kaolizer No. 1
(trade name, manufactured by Kao Corporation,
N,N,N',N'-tetramethyl-l,6-diaminohexane) .sup.2.sup.)Kaolizer No.
25 (trade name, manufactured by Kao Corporation,
6-(dimethylamino)-l-hexanol) .sup.3.sup.)TMAH: tetramethylammonium
hydroxide
[0091] It can be seen from the results shown in Table 1 that the
polishing compositions of Examples 1 to 11 each comprising the
improver of a selective ratio of the present invention have
markedly increased selective ratios of polishing rates, as compared
to the polishing compositions of Comparative Examples 1 to 5.
[0092] By using the polishing composition comprising the improver
of a selective ratio of a polishing rate of an insulating film to
that of a stopper film of the present invention, the ratio of a
polishing rate of an insulating film to that of a stopper film can
be increased.
[0093] The present invention being thus described, it will be
obvious that the same may be varied in many ways. Such variations
are not to be regarded as a departure from the spirit and scope of
the invention, and all such modifications as would be obvious to
one skilled in the art are intended to be included within t the
scope of the following claims.
* * * * *