U.S. patent application number 10/854785 was filed with the patent office on 2004-12-09 for metal polishing composition.
This patent application is currently assigned to SUMITOMO CHEMICAL COMPANY, LIMITED. Invention is credited to Ichiki, Naoki, Katsuda, Nobuyuki, Matsumi, Yasuo, Takashima, Masayuki.
Application Number | 20040244300 10/854785 |
Document ID | / |
Family ID | 33487331 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040244300 |
Kind Code |
A1 |
Ichiki, Naoki ; et
al. |
December 9, 2004 |
Metal polishing composition
Abstract
An object of the present invention is to provide a metal
polishing composition which can polish a metal such as Cu and Ta at
a high speed, has a higher efficiency of washing for a hydrophobic
low dielectric constant film, and is excellent stability without
precipitation of a polishing particle during storage (excellent in
stability for storing). The object is achieved by a metal polishing
composition comprising an anionic surfactant having 2 or more
anionic functional groups in a molecule, a polishing abrasive, an
inorganic salt, and water.
Inventors: |
Ichiki, Naoki; (Tokyo,
JP) ; Matsumi, Yasuo; (Tsukuba-shi, JP) ;
Takashima, Masayuki; (Sodegaura-shi, JP) ; Katsuda,
Nobuyuki; (Chiba-shi, JP) |
Correspondence
Address: |
FOLEY AND LARDNER
SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
SUMITOMO CHEMICAL COMPANY,
LIMITED
|
Family ID: |
33487331 |
Appl. No.: |
10/854785 |
Filed: |
May 27, 2004 |
Current U.S.
Class: |
51/307 ; 106/3;
257/E21.304; 51/308; 51/309 |
Current CPC
Class: |
C09G 1/02 20130101; H01L
21/3212 20130101; H01L 21/02074 20130101; C09K 3/1463 20130101 |
Class at
Publication: |
051/307 ;
106/003; 051/309; 051/308 |
International
Class: |
B24D 003/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 2003 |
JP |
2003-154754 |
Claims
1. A metal polishing composition comprising an anionic surfactant
having 2 or more anionic functional groups in a molecule, a
polishing abrasive, an inorganic salt and water.
2. The metal polishing composition according to claim 1, wherein
the anionic surfactant is an anionic surfactant having further an
ether linkage in a molecule.
3. The metal polishing composition according to claim 1, wherein
the anionic functional group is a functional group selected from
the group consisting of a sulfonic acid group, a phosphonic acid
group, a phosphoric acid group and a carboxylic acid group.
4. The metal polishing composition according to claim 1, wherein
the composition further contains a nonionic surfactant represented
by the formula
(I):Y--O--(C.sub.aH.sub.2aO).sub.b--(C.sub.xH.sub.2xO).sub.yZ
(I)(wherein a, b, x and y are independently a positive integer, and
Y and Z are independently a hydrogen atom or a hydrocarbon group
having a carbon number of 9 to 19).
5. The metal polishing composition according to claim 4, wherein a
is equal to x in the formula (I).
6. The metal polishing composition according to claim 4, wherein
the composition contains at least two nonionic surfactants
represented by the formula (I).
7. The metal polishing composition according to claim 6, wherein a
is equal to x in at least one nonionic surfactant represented by
the formula (I).
8. The metal polishing composition according to claim 1, wherein
the polishing abrasive is an inorganic particle.
9. The metal polishing composition according to claim 8, wherein
the inorganic particle is metal oxide.
10. The metal polishing composition according to claim 9, wherein
the metal oxide is silicon dioxide.
11. The metal polishing composition according to claim 1, wherein
the inorganic salt is a salt of an inorganic acid, and one selected
from the group consisting of alkylammonium hydroxide, ammonia,
alkylamine, alkanolamine and hydroxylamines.
12. The metal polishing composition according to claim 11, wherein
the inorganic acid is one selected from the group consisting of
nitric acid, phosphoric acid, hydrochloric acid and sulfuric
acid.
13. The metal polishing composition according to claim 1, wherein
the composition further contains an organic acid or a salt
thereof.
14. The metal polishing composition according to claim 9, wherein
the organic acid or a salt thereof is at least one selected from
the group consisting of acetic acid, citric acid, lactic acid,
malonic acid, tartaric acid, succinic acid, oxalic acid, amino
acid, and a salt thereof.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a metal polishing
composition.
BACKGROUND OF THE INVENTION
[0002] Recently, for polishing the surface of a semiconductor
substrate, chemical mechanical polishing (hereinafter, abbreviated
as CMP in some cases) has been mainly used.
[0003] On the other hand, currently, from the viewpoint of high
performance of LSI, a wiring material is changed from Al to Cu
having a low electric resistance, and an insulating film between
wirings is changed from a silicon oxide film to a low dielectric
constant film having a lower dielectric constant. Further, it is
being studied to form a wiring structure in which a barrier film
composed of Ta or TaN for preventing Cu from diffusing into a low
dielectric constant film is formed between Cu and a low dielectric
constant film. With change in such the wiring material, low
dielectric constant film and barrier film material, there is
desired a metal polishing composition which can polish these wiring
at a high speed, and can be used in CMP having high efficiency of
washing on the surface of a substrate after polishing.
[0004] For example, there are proposed a metal polishing
composition containing metal oxide such as silicon dioxide or
silicon nitride as a polishing abrasive, and an ammonium compound
such as ammonium nitrate as an inorganic salt (JP-No.10-310766A),
and a metal polishing composition containing a silicon dioxide
particle as a polishing abrasive, a first surfactant, and a second
surfactant (JP-A No.2002-155268). The efficiency of washing for a
low dielectric constant film of metal polishing agent described in
JP-A No.10-310766 is insufficient and, a rate of polishing a metal
such as Ta of the metal polishing agent described in JP-A
No.2002-155268 is insufficient, and its stability for storing is
insufficient.
SUMMARY OF THE INVENTION
[0005] An object of the present invention is to provide a metal
polishing composition which can polish a metal such as Cu and Ta at
a high speed, has a higher efficiency of washing for a hydrophobic
low dielectric constant film, and is excellent stability without
precipitation of a polishing abrasive during storage (excellent in
stability for storing).
[0006] The present inventors intensively studied and, as a result,
found that a metal polishing composition comprising an anionic
surfactant having 2 or more anionic functional groups in a
molecule, a polishing abrasive and an inorganic salt can polish a
metal such as Ta at a high speed, and is excellent in stability for
storing and efficiency of washing. Further, the present inventors
found that polishing rate or stability for storing is further
improved by further inclusion of a nonionic surfactant, and
completed the present invention.
[0007] That is, the present invention provides a metal polishing
composition comprising an anionic surfactant having 2 or more
anionic functional groups in a molecule, a polishing abrasive, an
inorganic salt, and water.
THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION
[0008] The present invention will be illustrated in detail
below.
[0009] The anionic surfactant used in the present invention
contains 2 or more anionic functional groups in a molecule.
[0010] As used herein, the anionic functional group is a group
which is dissociated in water and exhibits anionic property, and
examples include a sulfonic acid group, a phosphonic acid group, a
phosphoric acid group, a carboxylic acid group, and salts of these
functional groups.
[0011] The anionic surfactant used in the present invention is a
surfactant containing 2 or more of the aforementioned anionic
functional groups in a molecule, and may contain a functional group
other than the anionic functional group, provided that the
surfactant has negative charge in water, as a whole.
[0012] Examples of the anionic surfactant having 2 or more anionic
functional groups in a molecular structure include alkylene
disulfonic acid or alkylene disulfonate such as alkylene
disulfonate disodium salt, arylene disulfonic acid or arylene
disulfonate such as arylene disulfonate disodium salt, naphthalene
disulfonic acid formalin condensate or naphthalene disulfonic acid
formalin condensate salt such as naphtalene disulfonic acid
formalin condensate disodium salt, phenol disulfonic acid formalin
condensate in which X is hydrogen in the following formula (A) and
phenol disulfonic acid formalin condensate salt such as phenol
disulfonic acid formalin condensate disodium salt in which X is
sodium in the following formula (A), and phenylphenol disulfonic
acid formalin condensate in which X is hydrogen in the following
formula (B) and phenylphenol disulfonic acid formalin condensate
salt such as phenylphenol disulfonic acid formalin condensate
disodium salt in which X is sodium in the following formula (B).
1
[0013] (X is hydrogen or alkali metal) 2
[0014] (X is hydrogen or alkali metal)
[0015] From the viewpoint of stability for storing of the resulting
polishing composition, a preferable anionic surfactant used in the
present invention is an anionic surfactant further having an ether
linkage in a molecule. Examples of the anionic surfactant
containing an ether linkage together with 2 or more anionic
functional groups in a molecular structure include alkyl diphenyl
ether disulfonic acid, alkyl diphenyl ether diphosphonic acid,
alkyl diphenyl ether dicarboxylic aicd and salts thereof.
[0016] Among them, alkyl diphenyl ether disulfonic acid or a salt
thereof is preferable. For example, dodecyl diphenyl ether
disulfonic acid disodium salt, dodecyl dipheny ether disulfonic
acid diammonium salt, and dodecyl diphenyl ether disulfonic acid
ditriethanolamine salt are preferable.
[0017] These anionic surfactants may be used alone or in
combination of 2 or more.
[0018] The polishing abrasive used in the present invention may be
any of an inorganic particle and an organic particle. Examples of
the inorganic particle include particles containing, as a main
component, metal oxide such as silicon dioxide, zirconium oxide,
titanium oxide, silicon nitride, silicon carbide and manganese
dioxide. Among them, silicon dioxide is preferable, and fumed
silica and colloidal silica are more preferable. From the viewpoint
that during storage of the resulting metal polishing composition,
precipitation is suppressed, particle diameters are uniform, and
scratch on the surface of Cu or a low dielectric constant film is
suppressed, colloidal silica is further preferable.
[0019] The organic particle is a particle containing an organic
polymer compound as a main component, and examples include an
organic polymer compound such as a methacrylic resin such as PMMA,
a phenol resin, a melamine resin, a polystyrene resin and a
polycarbonate resin, a vinyl compound polymer obtained by emulsion
polymerization, and an ion exchange resin and a chelate resin
having ability to adsorb a particular metal. Among them, from the
viewpoint that polishing speed for a wiring, a low dielectric
constant film and a barrier film can be controlled, an ion exchange
resin and a chelate resin which adsorbs a metal such as Cu and Ta
are preferable.
[0020] From the viewpoint of suppression of occurrence of scratch
on the surface after polishing, an average particle diameter of a
polishing particle is preferably 10 .mu.m or smaller, more
preferably 1.0 .mu.m or smaller.
[0021] In addition, from the viewpoint of a polishing rate, an
average particle diameter is more preferably 0.005 .mu.m or
larger.
[0022] Polishing abrasive having a uniform particle diameter may be
used, or polishing particles having different average particle
diameters may be used by mixing them. For example, a mixture of
polishing particle having an average particle diameter of 0.1 .mu.m
and polishing particle having an average particle diameter of 0.1
.mu.m may be used.
[0023] As the inorganic salt used in the present invention, a salt
of an inorganic acid such as nitric acid, phosphoric aicd,
hydrochloric acid and sulfuric acid, with any one of alkylammonium
hydroxide, ammonia, alkylamine, alkanolamine and hydroxylamine is
preferable.
[0024] Examples of alkylammonium hydroxide include
tetramethylammonium hydroxide and tetraethyl ammonium hydroxide,
examples of alkylamine include methylamine, ethylamine, propylamine
and butylamine, examples of alkanolamine include monoethanolamine,
diethanolamine, triethanolamine, and 2-(2-aminoethoxy) ethanol, and
examples of hydroxylamine include hydroxylamine, and N,N-diethyl
hydroxylamine.
[0025] Among these inorganic salts, nitrate is preferable. Examples
of nitrate include tetramethylammonium hydroxide nitrate, ammonium
nitrate, monoethanolamine nitrate, and hydroxylamine nitrate. Among
them, ammonium nitrate is preferable.
[0026] These inorganic salts may be used alone or in combination of
2 or more. The inorganic salt may be prepared by mixing the
aforementioned inorganic acid with any one of alkylammonium
hydroxide, ammonia, alkylamine, alkanolamine and hydroxylamine, or
a commercially available inorganic salt may be used as it is.
[0027] From the viewpoint of improvement in a polishing speed to a
metal film such as a barrier metal film of Ta or the like, ammonium
nitrate is preferable.
[0028] The metal polishing composition of the present invention may
contain an organic acid or a salt thereof in addition to the
aforementioned inorganic acid. Examples of the organic acid include
carboxylic acid such as acetic acid, citric acid, lactic acid,
malonic acid, tartaric acid, succinic acid, oxalic acid, amino
acid, n-nonanoic acid, n-decanoic acid, n-octanoic acid,
2-ethylhexanoic acid, 2-methylheptanoic acid, 2-n-propyl-n-valeric
acid, 2,2-dimethyl-n-valeric acid, n-heptanoic acid,
2-methylhexanoic acid, 5-methylhexanoic acid, t-butylacetic acid,
n-hexanoic acid, 2,2-dimethyl-n-butyric acid, 3,3-n-butyric acid,
2-methyl-n-valeric acid, 3-methyl-n-valeric acid,
4-methyl-n-valeric acid, 2-methyl-n-butyric acid, 2-ethyl-n-butyric
acid, isovaleric acid, DL-2-methylbutyric acid, pivalic acid,
n-valeric acid, and n-butyric acid. Organic acids which are
generally commercially available may be used.
[0029] Among these organic acids, from the viewpoint of improvement
in efficiency of washing to a metal film, lactic acid,
tartaricacid, succinic acid, oxalic acid, n-octanoic acid,
2,2-dimethyl-n-valeric acid, n-heptanoic acid, 5-methylhexanoic
acid, t-butylacetic acid, n-hexanoic acid, 2,2-dimethyl-n-butyric
acid, and 2-methyl-n-butyric acid and salts thereof are preferable.
Examples of the salt include tetramethylammonium hydroxide salt,
ammonium salt, monoethanolamine salt, and hydroxylamine salt. Among
them, ammonium salt is particularly preferable. Most preferable is
ammonium oxalate.
[0030] These organic acids may be used alone or in combination of 2
or more.
[0031] The metal polishing composition of the present invention may
contain a nonionic surfactant.
[0032] Examples of the nonionic surfactant used include nonionic
surfactants which are contained in a conventional metal polishing
agent. For example, a nonionic surfactant represented by the
following formula (I) is preferable:
Y--O--(C.sub.aH.sub.2aO).sub.b--(C.sub.xH.sub.2xO).sub.y--Z (I)
[0033] (wherein a, b, x and y are independently a positive integer,
and Y and Z are independently a hydrogen atom or a hydrocarbon
group having a carbon number of from 9 to 19).
[0034] When one or both of Y and Z is (are) represented by a
hydrocarbon group, the hydrocarbon group is preferably a saturated
hydrocarbon group. The number of carbons in the hydrocarbon group
is from 9 to 19, preferably from 9 to 12, more preferably from 10
or 12.
[0035] In the formula (I), x and y represent a positive integer,
and x and a may be different or the same. From the viewpoint of
solubility in water, x is preferably 10 or smaller, more preferably
5 or smaller. And, x is preferably 3 or larger, more preferably 3.
From the viewpoint of wettability between a low dielectric constant
insulating film described below, y is preferably 10 or smaller,
more preferably 5or smaller. Usually, y is 1 or larger.
[0036] a is from 2 to 5, preferably from 2 or 3, more preferably 2.
From the viewpoint of solubility in an aqueous solution, b is
preferably 4 or larger, more preferably 5 or larger. From the
viewpoint of wettability between a low dielectric films having the
hydrophobic surface, 20 or smaller is preferable, 10 or smaller is
more preferable.
[0037] Examples of these nonionic surfactants include
polyoxyethylene polyoxypropylene decyl ether, polyoxyethylene
polyoxypropylene lauryl ether, polyoxyethylene polyoxypropylene
cetyl ether, polyoxyethylene polyoxypropylene stearyl ether, and
polyoxyethylene polyoxypropylene oleyl ether. Among them,
polyoxyethylene polyoxypropylene decyl ether, and polyoxyethylene
polyoxypropylene lauryl ether are preferable.
[0038] The case where a is equal to x (a=x) in the aforementioned
formula (I) is represented by the following formula (II):
Y--O--(C.sub.mH.sub.2mO).sub.n-Z (II)
[0039] (wherein m and n are the same or different and are a
positive integer, and Y and Z are as defined above)
[0040] In the formula (II), m is 2 to 5, preferably 2 or 3, more
preferably 2. From the viewpoint of solubility in an aqueous
solution, n is preferably 4 or larger, more preferably 5 or larger.
From the viewpoint of wettability between a hydrophobic film, 20 or
smaller is preferable, 10 or smaller is more preferable.
[0041] As the nonionic surfactant represented by the formula (II),
for example, polyoxyethylene decyl ether, polyoxyethylene lauryl
ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether,
and polyoxyethylene oleyl ether are better. Among them,
polyoxyethylene decyl ether, and polyoxyethylene lauryl ether are
preferable.
[0042] One or two or more of the aforementioned nonionic
surfactants may be used. When two or more kinds are used, it is
preferable that at least one kind is the nonionic surfactant
represented by the aforementioned formula (II).
[0043] The metal polishing composition of the present invention may
contain other components such as a corrosion inhibitor, an
oxidizing agent, and an antifoaming agent.
[0044] Examples of the corrosion inhibitor include corrosion
inhibitors which are generally used, such as azoles such as
1,2,3-benzotriazole, o-tolyltriazole, m-tolyltriazole,
p-tolyltriazole, carboxybenzotriazole, 1-hydroxybenzotriazole,
nitrobenzotriazole, and dihydroxypropylbenzotriaz- ole; mercapto
compounds such as thioglycolic acid, thiodiglycol, thioglycerol,
2-mercaptoimidazoline, 2-mercaptoethanol, and mercaptopropionic
acid; and aromatic hydroxy compounds such as sugar alcohols such as
mannitol and glucose, catechol, and pyrogallol. Among them,
preferable are 1,2,3-benzotriazole and benzotriazole
derivatives.
[0045] These corrosion inhibitors may be used alone or in
combination of two or more. By inclusion of these corrosion
inhibitors, there is a tendency that scratch and dishing are
prevented from occurring on the surface after polishing.
[0046] From the viewpoint of further improvement in a polishing
rate, the metal polishing composition of the present invention may
contain an oxidizing agent.
[0047] Examples of the oxidizing agent include hydrogen peroxide,
iodic acid, and iodate. Hydrogen peroxide is particularly
preferable.
[0048] These oxidizing agents maybe used alone or in combination of
two or more.
[0049] Examples of the antifoaming agent include an emulsifying
agent and a water-soluble alcohol, such as various emulsifying
agents such as polyether-type, special ester-type of trade name
Adecanol LG-135 (manufactured by ASAHI DENKA Co., Ltd.),
emulsion-type, silicon-based emulsion-type, special nonion-type of
trade name Adecanol LG-674 (manufactured by ASAHI DENKA Co., Ltd.),
and silicone-type, as well as water-soluble alcohols which are
generally known to suppress foamability, such as methanol, ethanol,
1-propanol, 2-propanol, 2-methyl-l-propanol, and
2-methoxyethanol.
[0050] The metal polishing composition of the present invention
comprises the aforementioned polishing abrasive, inorganic salt,
anionic surfactant and water. Further, an oxidizing agent, a
corrosion inhibitor, and an antifoaming agent are added thereto as
necessary.
[0051] A total amount of the polishing abrasive, the inorganic salt
and the anionic surfactant in the metal polishing composition is
usually from 0.1% by weight to 40% by weight, and water is from 60%
by weight to 99.9% by weight. When other components such as the
oxidizing agent, the corrosion inhibitor and the antifoaming agent
are added, a total amount thereof is usually from 0.001% by weight
to 15% by weight in the metal polishing composition.
[0052] Among a total amount of the polishing abrasive, inorganic
salt and the anionic surfactant, a content of the polishing
abrasive is from 0.05% by weight to 50% by weight, preferably from
0.12% by weight to 50% by weight. A content of the inorganic salt
is from 0.01% by weight to 25% by weight, preferably from 0.25% by
weight to 25% by weight, and a content of the anionic surfactant is
from 0.001% by weight to25% by weight, preferably from 0.25% by
weight to 25% by weight.
[0053] When the metal polishing composition contains the
aforementioned nonionic surfactant, a total amount of the anionic
surfactant and the nonionic surfactant is preferably in the same
range as that of the aforementioned content of the anionic
surfactant. It is preferable that, among a total amount of the
anionic surfactant and the nonionic surfactant, at least 50% by
weight or larger is the anionic surfactant. A ratio of the anionic
surfactant and the nonionic surfactant is preferably in a range of
1:0.01 to 1:1.
[0054] When the metal polishing agent of the present invention
contains an organic acid, content thereof is usually from 0.001 to
10% by weight in the metal polishing composition.
[0055] When other components such as the oxidizing agent, the
corrosion inhibitor and the antifoarming agent are contained, a
content of these components is such that the oxidizing agent is
usually from 0.1 to 15% by weight, and the corrosion inhibitor is
usually from 0.01 to 5.0% by weight in the metal polishing
composition.
[0056] When the aforementioned polishing abrasive, inorganic salt,
anionic surfactant and water and, further, other components such as
the oxidizing agent, the corrosion inhibitor and the antifoaming
agent are added, the order of adding them is not particularly
limited. For dispersing them, a homogenizer, an ultrasound, a wet
medium mill or the like are used.
[0057] A pH of the metal polishing composition of the present
invention is preferably 3 to 12, more preferably 3 to 9, further
preferably 7 to 9. A pH of the metal polishing composition is
adjusted by adding an inorganic acid or an organic acid, an
inorganic base such as alkali and ammonium, or an organic base such
as organic amine after the aforementioned respective components are
mixed. Examples of the inorganic acid include nitric acid,
phosphoric acid and sulfuric acid, examples of the inorganic base
include ammonium hydroxide, and examples of the organic base
includes amines. It is preferable that these are free from a metal
ion.
[0058] In addition, when the metal polishing composition of the
present invention contains an oxidizing agent, an oxidizing agent
is preferably mixed into the composition when polishing is
conducted.
[0059] It is suggested that a solution having the aforementioned
each component with the high concentration may be prepared, and
this may be used by diluting with water when polishing is
conducted.
[0060] The metal polishing composition of the present invention is
suitably used for polishing the surface of a semiconductor
substrate on which any one of a low dielectric constant film, a Cap
layer film which is a protecting film for a low dielectric constant
film, an insulating film utilized as an interlayer insulating film
between wirings, or the like is exposed. Further, the composition
is also suitably used for polishing the surface of a semiconductor
substrate on which a low dielectric constant film, a Cap layer
film, an interlayer insulating film, a Cu wiring film, a barrier Ta
or TaN film and the like are exposed.
[0061] Examples of the low dielectric constant film and the
protecting film for the low dielectric constant film include
inorganic films such as FSG (F-containing SiO.sub.2), SiOC
(carbon-containing SiO.sub.2), SiON (N-containing SiO.sub.2), SiC,
SiN and SiCN which are formed by a CVD method, polyorganosiloxane
films such as MSQ (methylsylsesquioxane), HSQ
(hydrogensylsesquioxane) and MHSQ (methylated
hydrogensylsesquioxane) which are formed on a substrate by coating
and firing, aromatic films such as PAE (polyaryl ether) and BCB
(divinylsiloxane-bis-benzocyclobuten- e), and organic films such as
Silk and porous Silk.
[0062] Examples of the interlayer insulating film between wirings
to be polished by the metal polishing composition of the present
invention include a CVD series SiO.sub.2 film which is formed using
tetraethoxysilane (TEOS) or silane gas, aHDP-SiO.sub.2 film
utilizing high density plasma, and a BPSG film in which a SiO.sub.2
film is doped with B or P, and the like.
[0063] The composition of the present invention is suitable for
polishing a surface having Cu as a wiring material for a
semiconductor device such as LSI, Ta or TaN as a metal used in a
barrier film, and a low dielectric constant film having the
hydrophobic surface having deteriorated wettability with water as
an insulating film between wirings, or a Cap layer film having the
hydrophobic surface formed on a low dielectric constant film for
protecting the low dielectric constant film, or a surface on which
the above films is exposed during polishing treatment.
EXAMPLES
[0064] The present invention will be explained below by way of
Examples, but the present invention is not limited by them.
Example 1
Preparation of Composition
[0065] To 0.3% by weight of silica, 1.0% by weight of ammonium
nitrate, 1.0% by weight of diammonium
dodecyldiphenyletherdisulfonate, 4% by weight of hydrogen peroxide
and 0.2% by weight of benzotriazole was added water to a total of
100% by weight, and the materials were mixed. Nitric acid was added
to the mixture to adjust to pH 4 (hereinafter, this was referred to
as composition 1).
Example 2
[0066] A composition was prepared according to the same manner as
that of Example 1 except that 0.1% by weight of polyoxyethylene
lauryl ether was further added to the composition 1 to a total of
100% by weight, and the materials were mixed (hereinafter, this was
referred to as composition 2).
Example 3
[0067] A composition was prepared according to the same manner as
that of Example 1 except that 0.1% by weight of polyoxyethylene
polyoxypropylene lauryl ether was added to the composition 1 to a
total of 100% by weight, the materials were mixed, and then,
ammonium hydroxide was added to the mixture so as to give pH 8.5
(hereinafter, this was referred to as composition 3).
Example 4
[0068] A composition was prepared according to the same manner as
that of Example 2 except that 0.04% by weight of ammonium oxalate
was further added to the composition 2, the materials were mixed to
a total of 100% by weight, and then, ammonium hydroxide was added
to the mixture so as to give pH 8.5 (hereinafter, this was referred
to as composition 4).
Comparative Example 1
[0069] A composition was prepared according to the same manner as
that of Example 1 except that dibutylnaphthalene sulfonate having
only one anionic functional group was used as an anionic surfactant
in place of diammonium dodecyl diphenyl ether disulfonate
(hereinafter, this was referred to as comparative composition
1).
Comparative Example 2
[0070] A composition was prepared according to the same manner as
that of Comparative Example 1 except that polyoxyethylene
.beta.-naphthyl ether sulfate ester sodium salt was used in place
of dibutylnaphthalene sulfonate salt (hereinafter, this was
referred to as comparative composition 2).
Comparative Example 3
[0071] A composition was prepared according to the same manner as
that of Comparative Example 1 except that polyoxyethylene tridecyl
ether sulfate ester sodium salt was used in place of
dibutylnaphthalene sulfate (hereinafter, this was referred to as
comparative composition 3).
Comparative Example 4
[0072] A composition was prepared according to the same manner as
that of Example 1 except that a surfactant was not added
(hereinafter, this was referred to as comparative composition
4).
Comparative Example 5
[0073] A composition was prepared according to the same manner as
that of Example 1 except that a surfactant and ammonium nitrate
were not added (hereinafter, this was referred to as comparative
composition 5).
Experimental Example 1
[0074] Using the compositions 1, 2, 3 and 4, and the comparative
compositions 1, 2, 3, 4 and 5, stability for storing, polishing
rate, and efficiency for removing polishing particle adhered to a
low dielectric constant film, a Cu film and a Ta film after
completion of polishing were estimated.
[0075] [Polishing Conditions]
[0076] Polishing machine: Leaf-type CMP apparatus CMS-200M
(manufactured by NuFlare Technology Inc.)
[0077] Pad:-polyurethane type
[0078] Rotation number of pad surface plate: 78 rpm
[0079] Rotation number of stage for holding wafer to be polished:
75 rpm
[0080] Polishing pressure: 15 KPa
[0081] Polishing slurry flow rate: 150 ml/min
[0082] Washing step: Roll brush washing, pencil brush washing,
megasonic washing, and spin drying were performed in this order
using ultrapure water.
[0083] [Measurement of Ta Film Polishing Rate]
[0084] A Ta film was made on a Si wafer using a sputtering method,
and this film was used as a wafer to be polished to perform
polishing according to the aforementioned polishing conditions.
Before and after polishing, a thickness of a film was measured with
an electron microscope. A polishing rate was obtained by dividing a
difference in film thickness before and after polishing by a
polishing time.
[0085] [Calculation of Particle Removal Rate]
[0086] Using a low dielectric constant film (SiOC film) made on a
Si wafer by a CVD (Chemical Vapor Deposition) method, a Cu film
made on a Si wafer by a plating method, and a Ta film made on a Si
wafer by a sputtering method as a wafer to be polished, polishing
was performed according to the aforementioned polishing conditions,
to adhere a polishing particle onto the film. Before and after
washing, the number of adhered particles having a particle diameter
of 0.2 micron or more was measured with a particle measuring
apparatus (WM-1500 (manufactured by TOPCON CORPORATION)) on a
wafer. From the numbers of adhered particles before and after
washing, a rate of particles removed by washing was calculated
according to the following equation.
[0087] Method of calculating rate of removed particles 1 Rate of
removed particles ( % ) = ( 1 - ( number of adhered particles after
washing ) / ( number of adhered particles before washing ) )
.times. 100
[0088] The number of particles derived from the metal polishing
agent on a low dielectric constant film before washing was about
10000 to 12000.
[0089] [Estimation of Stability for Storing]
[0090] In the compositions 1, 2, 3 and 4, and comparative
compositions 1, 2, 3, 4 and 5, an average particle diameter of a
polishing particle was measured immediately after preparation and
after allowing to stand overnight (about 8 hours) to estimate
stability of a particle of each composition. Micro Track UPA
manufactured by NIKKISO Co., Ltd. was used for measuring an average
particle diameter.
1 TABLE 1 Comparative Comparative Comparative Comparative
Comparative Composition Composition Composition Composition
composition composition composition composition composition 1 2 3 4
1 2 3 4 5 Silica *.sup.1 (% by 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3
weight) Ammonium nitrate 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 (% by
weight) Ammonium oxalate 0.04 (% by weight) Surfactant A *.sup.2
1.0 1.0 1.0 1.0 Surfactant B *.sup.3 0.1 0.1 Surfactant C *.sup.4
0.1 Surfactant D *.sup.5 1.0 Surfactant E *.sup.6 1.0 Surfactant F
*.sup.7 1.0 Ta film 520 640 520 580 520 -- -- 563 32 polishing rate
(.ANG. min) Film SiOC 99.5 99.4 99.4 99.4 99.3 -- -- 90.7 88.1
particle Cu 99.5 99.5 99.5 99.9 99.5 -- -- 92.1 90.5 removing Ta
99.5 99.5 99.5 99.9 99.5 -- -- 92.3 92.3 rate (%) Average particle
8 12 12 12 15 Not Not 8 8 diameter of determined determined
polishing particle immediately after compounding (nm) Average
particle 12 16 16 16 Not Not Not 12 8 diameter of determined
determined determined polishing particle after allowing to stand
overnight (nm) *.sup.1Colloidal silica available as trade name
"Ludox SM-30" manufactured by W. R. Grace & Co., average
particle diameter: 7 nm *.sup.2Anionic surfactant which is
available as diammonium dodecyldiphenyletherdisulfonate and has an
ether linkage and two anionic functional groups. *.sup.3Nonionic
surfactant which is available as polyoxyethylene lauryl ether and
in which Y is a lauryl group as a hydrocarbon group having a carbon
number of 12, m is 2, n is 8, and Z is hydrogen in the
aforementioned formula (II). *.sup.4Nonionic surfactant which is
available as polyoxyethylene polyoxypropylene lauryl ether and in
which Y is a lauryl group as a hydrocarbon group having a carbon
number of 12, a is 2, b is 8, x is 3, y is 2, and Z is hydrogen in
the formula (I). *.sup.5Anionic surfactant which is available as
dibutylnaphthalenesulfonic acid and has one anionic functional
group. *.sup.6Anionic surfactant which is available as
polyoxyethylene .beta.-naphthyl ether sulfate ester sodium salt and
has one anionic functional group. *.sup.7Anionic surfactant which
is available as polyoxyethylene tridecylether sulfate ester sodium
salt and has one anionic functional group.
[0091] All of the compositions 1 to 4 were able of polishing Ta at
a high speed, have high particle removability on a low dielectric
film after polishing, and hardly had adhered polishing abrasive. In
addition, after preparation, precipitation did not occur, and
stability for storing was excellent.
[0092] In addition, the composition 4 had extremely better particle
removability on a metal film after polishing.
[0093] On the other hand, even in the case of using an anionic
surfactant, in the composition using an anionic surfactant having
only one anionic functional group as in the comparative composition
1, whereas a polishing rate and efficiency of washing were similar
to the compositions 1 to 4, after preparation, polishing particles
were aggregated, and an aggregate was precipitated, and thus, there
was a problem on stability for storing. Also in the comparative
compositions 2 and 3 using an anionic surfactant having one anionic
functional group, polishing abrasive were aggregated, an aggregate
was precipitated, and thus, the stability for storing is
insufficient. In addition, in the comparative composition 4
containing no surfactant, since wettability between a low
dielectric constant film is deteriorated, and the surface is
immediately dried, efficiency of washing thereafter is
insufficient, and in the comparative composition 5 containing no
nitrate, a rate of polishing Ta was low.
[0094] According to the present invention, there can be provided a
metal polishing composition which can polish a metal such as Cu and
Ta at a high speed, has high efficiency of washing to a hydrophobic
low dielectric constant film, and is excellent in stability for
storing, and in which a polishing abrasive is not precipitated
during storage.
* * * * *