U.S. patent application number 14/007749 was filed with the patent office on 2014-01-16 for polishing composition and polishing method.
This patent application is currently assigned to FUJIMI INCORPORATED. The applicant listed for this patent is Yoshihihro Ezawa, Tatsuhiko Hirano, Shogo Onishi, Shuichi Tamada. Invention is credited to Yoshihihro Ezawa, Tatsuhiko Hirano, Shogo Onishi, Shuichi Tamada.
Application Number | 20140014872 14/007749 |
Document ID | / |
Family ID | 46931269 |
Filed Date | 2014-01-16 |
United States Patent
Application |
20140014872 |
Kind Code |
A1 |
Tamada; Shuichi ; et
al. |
January 16, 2014 |
POLISHING COMPOSITION AND POLISHING METHOD
Abstract
Disclosed is a polishing composition containing a pH-lowering
substance and a pH-buffering agent. The difference in absolute
value between the pH of the polishing composition immediately after
adding a 31% by weight hydrogen peroxide solution thereto at 5.16 g
per 100 g of the polishing composition and the pH of the polishing
composition after leaving to stand for eight days therefrom is 0.5
or less. Also disclosed is another polishing composition containing
a pH-lowering substance and a pH-controlling agent. In comparison
to the amount of a basic substance in the polishing composition
immediately after adding a 31% by weight hydrogen peroxide solution
thereto at 5.16 g per 100 ml of the polishing composition, the
amount of a basic substance in the polishing composition after
leaving to stand for eight days therefrom is increased by no less
than 0.1 mM.
Inventors: |
Tamada; Shuichi;
(Kiyosu-shi, JP) ; Hirano; Tatsuhiko; (Kiyosu-shi,
JP) ; Ezawa; Yoshihihro; (Kiyosu-shi, JP) ;
Onishi; Shogo; (Kiyosu-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tamada; Shuichi
Hirano; Tatsuhiko
Ezawa; Yoshihihro
Onishi; Shogo |
Kiyosu-shi
Kiyosu-shi
Kiyosu-shi
Kiyosu-shi |
|
JP
JP
JP
JP |
|
|
Assignee: |
FUJIMI INCORPORATED
Kiyosu-shi, Aichi
JP
|
Family ID: |
46931269 |
Appl. No.: |
14/007749 |
Filed: |
March 28, 2012 |
PCT Filed: |
March 28, 2012 |
PCT NO: |
PCT/JP2012/058195 |
371 Date: |
September 26, 2013 |
Current U.S.
Class: |
252/79.1 |
Current CPC
Class: |
C09K 3/1409 20130101;
C23F 3/06 20130101; H01L 21/3212 20130101; C09K 3/1463 20130101;
C09G 1/02 20130101 |
Class at
Publication: |
252/79.1 |
International
Class: |
C23F 3/06 20060101
C23F003/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2011 |
JP |
2011-076475 |
May 31, 2011 |
JP |
2011-122438 |
Claims
1. A polishing composition comprising: a substance that lowers the
pH of an aqueous solution in the presence of an oxidizing agent;
and a pH-buffering agent, wherein the difference in absolute value
between the pH of the polishing composition immediately after
adding a 31% by weight hydrogen peroxide solution thereto at 5.16 g
per 100 g of the polishing composition and the pH of the polishing
composition after leaving to stand for eight days from the addition
of the hydrogen peroxide solution is 0.5 or less.
2. The polishing composition according to claim 1, wherein the
pH-buffering agent is a compound having an amide group.
3. The polishing composition according to claim 1, wherein the
pH-buffering agent is an amphoteric amino acid having at least one
of a sulfo group and a carboxyl group.
4. The polishing composition according to claim 1, wherein the
pH-buffering agent is a compound represented by the following
general formula (1), in which R.sub.1 and R.sub.3 each
independently represent a non-substituted or substituted
straight-chain alkyl group with 1 to 4 carbon atoms, R.sub.2
represents a hydrogen atom, a hydroxyl group, a sulfo group, a
carboxyl group, an amino group, an amide group, a carbamoyl group,
a nitro group, a methoxy group, an ethoxy group, a halogen group, a
phenyl group, an acetyl group, or a non-substituted or substituted
alkyl group with 1 to 4 carbon atoms, and X represents a sulfo
group, a carboxyl group, or a salt thereof. ##STR00003##
5. The polishing composition according to claim 4, wherein in the
general formula (1), X is a sulfo group or a salt thereof.
6. A polishing composition comprising: a substance that lowers the
pH of an aqueous solution in the presence of an oxidizing agent;
and a pH-controlling agent, wherein in comparison to the amount of
a basic substance in the polishing composition immediately after
adding a 31% by weight hydrogen peroxide solution thereto at 5.16 g
per 100 ml of the polishing composition, the amount of a basic
substance in the polishing composition after leaving to stand for
eight days from the addition of the hydrogen peroxide solution is
increased by no less than 0.1 mM.
7. The polishing composition according to claim 6, wherein the
difference in absolute value between the pH of the polishing
composition immediately after adding a 31% by weight hydrogen
peroxide solution thereto at 5.16 g per 100 ml of the polishing
composition and the pH of the polishing composition after leaving
to stand for eight days from the addition of the hydrogen peroxide
solution is 0.5 or less.
8. The polishing composition according to claim 6, wherein the
basic compound is ammonia.
9. The polishing composition according to claim 6, wherein in
comparison to the amount of a basic substance in a 100 ml of
aqueous solution containing 5.0 mM of the pH-controlling agent
immediately after adding 10.32 g of a 31% by weight hydrogen
peroxide solution thereto, the amount of a basic substance in the
aqueous solution after leaving to stand for eight days from the
addition of the hydrogen peroxide solution is increased by no less
than 0.2 mM.
10. The polishing composition according to claim 6, wherein the
pH-controlling agent is a compound having an amide group.
11. The polishing composition according to claim 6, wherein the
pH-controlling agent is an amphoteric amino acid having at least
one of a sulfo group and a carboxyl group.
12. The polishing composition according to claim 6, wherein the
pH-controlling agent is a compound represented by the following
general formula (2), in which R.sub.1 and R.sub.3 each
independently represent a non-substituted or substituted
straight-chain alkyl group with 1 to 4 carbon atoms, R.sub.2
represents a hydrogen atom, a hydroxyl group, a sulfo group, a
phosphono group, a carboxyl group, an amino group, an amide group,
a carbamoyl group, a nitro group, a methoxy group, an ethoxy group,
a halogen group, a phenyl group, an acetyl group, an acyl group, or
a non-substituted or substituted alkyl group with 1 to 4 carbon
atoms, and X represents a sulfo group, a carboxyl group, or a salt
thereof ##STR00004##
13. The polishing composition according to claim 12 wherein in the
general formula (2), X is a sulfo group or a salt thereof.
14. A polishing method comprising: providing a metal to be
polished; and using a polishing composition to polish the metal,
wherein the polishing composition contains a substance that lowers
the pH of an aqueous solution in the presence of an oxidizing
agent, and a pH-buffering agent, and wherein the difference in
absolute value between the pH of the polishing composition
immediately after adding a 31% by weight hydrogen peroxide solution
thereto at 5.16 g per 100 g of the polishing composition and the pH
of the polishing composition after leaving to stand for eight days
from the addition of the hydrogen peroxide solution is no more than
0.5.
15. The polishing method according to claim 14, further comprising
adding an oxidizing agent to the polishing composition prior to
said using.
16. A method of producing a metal-containing substrate, comprising:
providing a metal to be polished; and polishing the metal with a
polishing composition containing a substance that lowers the pH of
an aqueous solution in the presence of an oxidizing agent, and a
pH-buffering agent, wherein the difference in absolute value
between the pH of the polishing composition immediately after
adding a 31% by weight hydrogen peroxide solution thereto at 5.16 g
per 100 g of the polishing composition and the pH of the polishing
composition after leaving to stand for eight days from the addition
of the hydrogen peroxide solution is no more than 0.5.
17. A polishing method comprising: providing a metal to be
polished; and using a polishing composition to polish the metal,
wherein the polishing composition contains a substance that lowers
the pH of an aqueous solution in the presence of an oxidizing
agent, and a pH-controlling agent, wherein in comparison to the
amount of a basic substance in the polishing composition
immediately after adding a 31% by weight hydrogen peroxide solution
thereto at 5.16 g per 100 ml of the polishing composition, the
amount of a basic substance in the polishing composition after
leaving to stand for eight days from the addition of the hydrogen
peroxide solution is increased by no less than 0.1 mM.
18. The polishing method according to claim 17, further comprising
adding an oxidizing agent to the polishing composition prior to
said using.
19. A method of producing a metal-containing substrate, comprising:
providing a metal to be polished; and polishing the metal with a
polishing composition containing a substance that lowers the pH of
an aqueous solution in the presence of an oxidizing agent, and a
pH-controlling agent, wherein in comparison to the amount of a
basic substance in the polishing composition immediately after
adding a 31% by weight hydrogen peroxide solution thereto at 5.16 g
per 100 ml of the polishing composition, the amount of a basic
substance in the polishing composition after leaving to stand for
eight days from the addition of the hydrogen peroxide solution is
increased by no less than 0.1 mM.
Description
TECHNICAL FIELD
[0001] The present invention relates to a polishing composition
used, for example, in polishing a metal-containing substrate
surface (hereinafter referred to as "object to be polished") in a
large-scale integration (hereinafter referred to as "LSI").
BACKGROUND ART
[0002] New microfabrication techniques are being developed with the
realization of higher integration degrees and higher operational
speeds of LSIs. A chemical mechanical polishing (hereinafter
referred to as "CMP") method is one such technique that is applied
to planarization of interlayer insulating films, formation of
contact plugs, and formation of embedded wiring in LSI
manufacturing processes, particularly in multilayer wiring forming
processes. This technique is disclosed, for example, in Patent
Document 1.
[0003] In forming contact plugs, tungsten is used as an embedding
material and as a material of an interdiffusion barrier for the
contact plugs. A method where excess portions, other than contact
plugs, are removed by CMP is used for forming the contact plugs. In
forming embedded wiring, to make an LSI high in performance, copper
or a copper alloy is recently being used as a conductive substance
that is to be a wiring material. With copper or a copper alloy, it
is difficult to perform microfabrication by a dry etching method
that is frequently used in forming conventional aluminum alloy
wiring, and therefore a so-called damascene method, with which a
thin film of copper or a copper alloy is deposited on and embedded
in an insulating film having a groove formed in advance and the
thin film is thereafter removed by CMP at portions other than in
the groove to form embedded wiring, is mainly used. Generally in a
metal polishing composition used in CMP, an acid or other polishing
accelerator and an oxidizing agent are contained and abrasive
grains are further contained as necessary. In order to improve
flatness of a polished object, it is also considered effective to
use a polishing composition to which a metal anticorrosive is
further added. For example, use of a polishing composition
containing either or both of aminoacetic acid and amidosulfuric
acid, an oxidizing agent, benzotriazole, and water is disclosed in
Patent Document 2.
[0004] However, when an oxidizing agent is added to a polishing
composition, there is a problem that the polishing performance
changes with time. Although various factors responsible for the
change of polishing performance have been confirmed, one of the
factors is a change in the pH of the polishing composition due to
interaction of chemical substances in the polishing composition,
such as a polishing accelerator and a metal anticorrosive, with the
oxidizing agent.
[0005] The pH is very important in designing a metal polishing
composition and generally, the pH of a polishing composition is set
based on a Pourbaix diagram. For example, Patent Document 3
discloses that it is important for a copper polishing composition
to have a pH of approximately 6.0 in order to form copper(I) oxide.
When the pH of the polishing composition decreases, it is difficult
for copper oxide to form on a copper surface and dissolution of
metallic copper increases. Also, when the pH of the polishing
composition increases, copper in the solution may precipitate,
adhere to the wafer surface, and thereby cause formation of
scratches. Therefore, in order to obtain a flat surface without
defects after CMP, it is required that the pH of a metal polishing
composition be constantly stable.
[0006] Although Patent Document 4 discloses a technique of
stabilizing the pH of a polishing composition during a copper
polishing process that lasts for a few minutes, there is no
specific disclosure of suppressing the change with time of the pH
over a longer period and the technique is technically difficult as
well.
PRIOR ART DOCUMENTS
[0007] Patent Document 1: Japanese Laid-Open Patent Publication No.
62-102543 [0008] Patent Document 2: Japanese Laid-Open Patent
Publication No. 8-83780 [0009] Patent Document 3: Japanese National
Phase Laid-Open Patent Publication No. 2000-501771 [0010] Patent
Document 4: Japanese National Phase Laid-Open Patent Publication
No. 2006-506809
SUMMARY OF THE INVENTION
Problems that the Invention is to Solve
[0011] An objective of the present invention is to provide a
polishing composition that is used in manufacturing LSIs and that
is capable of suppressing the change of pH with time after addition
of an oxidizing agent thereto, a polishing method using the
polishing composition, and a method of producing a substrate by the
polishing method.
Means for Solving the Problems
[0012] The present inventors have conducted diligent studies and
found out a polishing composition having stable characteristics not
only during polishing but also over a long period from the point of
addition of an oxidizing agent for the purpose of use in polishing
until the polishing composition is used up.
[0013] That is, a first aspect of the present invention provides a
polishing composition containing a substance that lowers the pH of
an aqueous solution in the presence of an oxidizing agent, and a
pH-buffering agent. The polishing composition is characterized in
that the difference in absolute value between the pH immediately
after adding a 31% by weight hydrogen peroxide solution thereto at
5.16 g, that is, adding hydrogen peroxide thereto at 1.6 g per 100
g of the polishing composition and the pH after leaving to stand
for eight days from the addition of the hydrogen peroxide solution
is 0.5 or less.
[0014] A second aspect of the present invention provides a
polishing composition containing a substance that lowers the pH of
an aqueous solution in the presence of an oxidizing agent, and a
pH-controlling agent. The polishing composition is characterized in
that in comparison to the amount of a basic substance in the
polishing composition immediately after adding a 31% by weight
hydrogen peroxide solution thereto at 5.16 g per 100 ml of the
polishing composition, the amount of a basic substance in the
polishing composition after leaving to stand for eight days from
the addition of the hydrogen peroxide solution is increased by no
less than 0.1 mM.
[0015] A third aspect of the present invention provides a method of
polishing a metal with the polishing composition according to the
first or second aspect. A fourth aspect of the present invention
provides a method of producing a metal-containing substrate, the
method including polishing a metal by the method according to the
third aspect.
Effects of the Invention
[0016] According to the present invention, a polishing composition
that is used in manufacturing LSIs and is low in change of pH with
time, a polishing method using the polishing composition, and a
method of producing a substrate by the polishing method are
provided.
MODE FOR CARRYING OUT THE INVENTION
[0017] A first embodiment of the present invention will now be
described below.
[0018] A polishing composition of the present embodiment contains a
substance that lowers the pH of an aqueous solution in the presence
of an oxidizing agent, and a pH-buffering agent and optionally
further contains abrasive grains and another additive. The
polishing composition is prepared by mixing these components in a
solvent, such as water.
[0019] The polishing composition of the present embodiment is
mainly used in polishing for manufacturing an LSI such as described
in the "BACKGROUND ART" section, particularly in a metal polishing
process. More specifically, the polishing composition is used in
polishing for forming metal wiring, contact holes, and via holes in
an LSI. Examples of the metal polished with the polishing
composition include copper, tungsten, tantalum, titanium, cobalt,
ruthenium, and oxides, alloys, and compounds thereof. Among these,
copper, tantalum, titanium, ruthenium, and oxides, alloys, and
compounds thereof are preferable, and copper and oxides, alloys,
and compounds thereof are more preferable.
(Oxidizing Agent)
[0020] The oxidizing agent has an action of oxidizing the surface
of an object to be polished and the addition of an oxidizing agent
to the polishing composition provides an advantage that the rate of
polishing with the polishing composition is improved.
[0021] The oxidizing agent that may be used is, for example, a
peroxide. Examples of a peroxide include hydrogen peroxide,
peracetic acid, percarbonates, urea peroxide, perchloric acid, and
persulfates, such as sodium persulfate, potassium persulfate, and
ammonium persulfate. Among these, persulfates and hydrogen peroxide
are preferable from the standpoint of the polishing rate and
hydrogen peroxide is especially preferable from the standpoints of
the stability in an aqueous solution and a reduction in the
environmental impact.
[0022] The content of the oxidizing agent in the polishing
composition is preferably no less than 0.1 g/L, more preferably no
less than 1 g/L, and even more preferably no less than 3 g/L. As
the oxidizing agent content increases, the rate of polishing with
the polishing composition is advantageously improved.
[0023] The content of the oxidizing agent in the polishing
composition is preferably 200 g/L or less, more preferably 100 g/L
or less, and even more preferably 40 g/L or less. A decrease in the
oxidizing agent content is advantageous in that the material cost
of the polishing composition is reduced and additionally, in that
the burden of treating the polishing composition after use in
polishing, that is, the burden of waste liquid treatment is
reduced. Further, there is an advantage that excessive oxidation of
the surface of an object to be polished by the oxidizing agent is
made less likely to occur.
(pH-Lowering Substance)
[0024] The pH-lowering substance that lowers the pH of an aqueous
solution in the presence of an oxidizing agent is a substance among
surfactants, water-soluble polymers, amine compounds, metal
anticorrosives, and organic solvents that satisfies the following
condition. That is, an aqueous solution containing 0.05% by weight
of a surfactant or a water-soluble polymer or 5 mmol/L of an amine
compound, a metal anticorrosive, or an organic solvent is prepared,
and the pH of the aqueous solution is adjusted to approximately 7.5
by adding potassium hydroxide or sulfuric acid as a pH adjusting
agent. Then, the pH of the aqueous solution immediately after
adding a 31% by weight hydrogen peroxide solution thereto at 10.32
g per 100 g of the aqueous solution, that is, adding hydrogen
peroxide thereto at 3.2 g per 100 g of the aqueous solution, and
the pH of the aqueous solution after leaving to stand for eight
days under ordinary temperature (23.degree. C. to 27.degree. C.)
from the addition of hydrogen peroxide are compared. The condition
is that the difference in absolute value between these pH values is
no less than 0.5.
[0025] Examples of a surfactant satisfying the condition for the
pH-lowering substance include a nonionic surfactant having a
polyoxyalkylene group. Examples of the nonionic surfactant include
polyoxyethylene alkyl ether.
[0026] Examples of a water-soluble polymer satisfying the condition
for the pH-lowering substance include a water-soluble polymer
having a nitrogen atom in its structure. Examples of a
water-soluble polymer having a nitrogen atom in its structure
include a reaction condensate of at least one raw material monomer
and a second raw material monomer, the at least one raw material
monomer being selected from among bases having two or more amino
groups, for example, diethylenetriamine, triethylenetetramine,
tetraethylenepentamine, iminobispropylamine,
dimethylaminoethylamine, dimethylaminopropylamine,
diethylaminoethylamine, diethylaminopropylamine,
dibutylaminopropylamine, ethylaminoethylamine, 1,2-diaminopropane,
1,3-diaminopropane, 1,4-diaminobutane, methylaminopropylamine,
diethylenetriamine, triethylenetetramine, tetraethylenepentamine,
pentaethylenehexamine, dipropylenetriamine, tripropylenetetramine,
2-hydroxyaminopropylamine, methylbis-(3-aminopropyl)amine,
dimethylaminoethoxypropylamine, 1,2-bis-(3-aminopropoxy)-ethane,
1,3-bis-(3-aminopropoxy)-2,2-dimethylpropane,
.alpha.,.omega.-bis-(3-aminopropoxy)-polyethylene glycol ether,
iminobispropylamine, methyliminobispropylamine,
laurylaminopropylamine, diethanolaminopropylamine,
N-aminoethylpiperidine, N-aminoethylpipecoline,
N-aminoethylmorpholine, N-aminopropylpiperidine,
N-aminopropyl-2-pipecoline, N-aminopropyl-4-pipecoline,
N-aminopropyl-4-morpholine, and N-aminopropylmorpholine, and the
second raw material monomer being composed of at least one
polybasic acid selected, for example, from among oxalic acid,
malonic acid, succinic acid, glutaric acid, adipic acid, and
pimelic acid. Another example of a water-soluble polymer having a
nitrogen atom in its structure is a product of reacting at least
one substance selected, for example, from among urea and
epihalohydrins with the reaction condensate of the first raw
material monomer and the second raw material monomer.
[0027] Examples of an amine compound satisfying the condition for
the pH-lowering substance include a compound having an amino group.
Examples of a compound having an amino group include
ethylenediaminetetraacetic acid (EDTA), N-methylethylenediamine,
N,N,N,N-tetrakis(2-hydroxypropyl)ethylenediamine,
1,4-diazabicyclo[2,2,2]octane, and
N,N-di-tert-butylethane-1,2-diamine.
[0028] Examples of a metal anticorrosive satisfying the condition
for the pH-lowering substance include 1H-benzotriazole,
5-methyl-1H-benzotriazole,
1-[N,N-bis(hydroxyethyl)aminomethyl]-4-methylbenzotriazole,
1-[N,N-bis(hydroxyethyl)aminomethyl]-5-methylbenzotriazole,
3-mercapto-1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole,
3-mercaptomethyl-4H-1,2,4-triazole, benzoylhydrazine,
salicylhydrazide, 4-hydroxybenzohydrazide, dihydrazide
isophthalate, dihydrazide terephthalate, benzohydroxamic acid,
salicylhydroxamic acid, 1H-benzotriazole-1-methanol, and
2,2-biphenol.
[0029] Examples of an organic solvent satisfying the condition for
the pH-lowering substance include a compound having an alcoholic
hydroxyl group. Examples of a compound having an alcoholic hydroxyl
group include methanol, ethanol, propanol, ethylene glycol, and
polyethylene glycol.
[0030] With regard to aqueous solutions containing any of the
substances described above as examples of the pH-lowering
substance, the changes in pH with time were examined in the
presence of and in the absence of hydrogen peroxide and the results
are shown in Table 1. Specifically, each aqueous solution
containing a predetermined amount of a pH-lowering substance was
adjusted to a pH of approximately 7.5 by addition of potassium
hydroxide or sulfuric acid and thereafter left to stand in storage
for eight days under ordinary temperature (23.degree. C. to
27.degree. C.) using a constant temperature bath. The pH value of
each aqueous solution measured immediately after the pH adjustment,
the pH value of each aqueous solution measured after being left to
stand for the eight days, and the amount of pH change that occurred
within the eight days are respectively indicated in the "pH
immediately after preparation" column, the "pH after eight days"
column, and the "pH change amount" column in the "Without hydrogen
peroxide" column. Also, a 31 by weight hydrogen peroxide solution
was added to each aqueous solution immediately after the pH
adjustment to approximately 7.5 at 10.32 g per 100 g of the aqueous
solution (that is, hydrogen peroxide was added at 3.2 g per 100 g
of the aqueous solution) and thereafter each aqueous solution was
left to stand in storage for eight days under ordinary temperature
(23.degree. C. to 27.degree. C.) using a constant temperature bath.
The pH value of each aqueous solution measured immediately after
the addition of hydrogen peroxide, the pH value of each aqueous
solution measured after being left to stand for the eight days, and
the amount of pH change that occurred within the eight days are
respectively indicated in the "pH immediately after preparation"
column, the "pH after eight days" column, and the "pH change
amount" column in the "With hydrogen peroxide" column. The pH of
each aqueous solution was measured under ordinary temperature
(23.degree. C. to 27.degree. C.) using a pH meter (F-52, from
Horiba, Ltd.).
TABLE-US-00001 TABLE 1 With hydrogen peroxide Without hydrogen
peroxide pH-lowering substance pH immediately pH after pH change pH
immediately pH after pH change Name Content after preparation eight
days amount after preparation eight days amount Example 1 none --
7.44 7.43 -0.01 7.48 7.47 -0.01 Example 2 1-[N,N- 5 mmol/L 7.50
5.24 -2.26 7.47 7.46 -0.01 bis(hydroxyethyl)aminomethyl]-
5-methylbenzotriazole Example 3 1-[N,N- 5 mmol/L 7.50 5.24 -2.26
7.47 7.46 -0.01 bis(hydroxyethyl)aminomethyl]-
4-methylbenzotriazole Example 4 1H-benzotriazole 5 mmol/L 7.46 4.78
-2.68 7.46 7.40 -0.06 Example 5 5-methyl-1H-benzotriazole 5 mmol/L
7.45 4.80 -2.65 7.45 6.32 -1.13 Example 6 trimethylamine 5 mmol/L
7.58 5.75 -1.83 7.55 7.48 -0.07 Example 7 2,2-methyliminodiethanol
5 mmol/L 7.45 5.21 -2.24 7.46 7.40 -0.06 Example 8
diethylenetriamine-adipic acid 0.05 wt. % 7.53 6.42 -1.11 7.55 7.44
-0.11 condensate Example 9 diethylenetriamine-succinic acid 0.05
wt. % 7.55 5.74 -1.81 7.55 7.44 -0.11 condensate Example 10
Polyoxyethylene lauryl ether 0.05 wt. % 7.44 6.70 -0.74 7.55 7.44
-0.11 Example 11 Ethanol 5 mmol/L 7.42 6.72 -0.70 7.55 7.51 -0.04
(pH-buffering agent)
[0031] The pH-buffering agent is blended in the polishing
composition so that the difference in absolute value between the pH
of the polishing composition immediately after adding a 31% by
weight hydrogen peroxide solution thereto at 5.16 g per 100 g of
the polishing composition, that is, adding hydrogen peroxide
thereto at 1.6 g per 100 g of the polishing composition and the pH
of the polishing composition after leaving to stand for eight days
after from the addition of the hydrogen peroxide solution is 0.5 or
less. If the difference in absolute value between these pH values
is 0.5 or less, the lowering of polishing performance with time of
the polishing composition can be suppressed to a level that does
not present a problem in terms of practical use and a polishing
composition of excellent stability can be provided.
[0032] The pH-buffering agent is preferably a compound having an
amide group and is more preferably an amphoteric amino acid further
having at least one of a sulfo group and a carboxyl group in
addition to the amide group. The pH-buffering agent may be a
compound represented by the following general formula (1).
##STR00001##
[0033] In the general formula (1), R.sub.1 and R.sub.3 each
independently represent a non-substituted or substituted
straight-chain alkyl group with 1 to 4 carbon atoms. R.sub.2
represents a hydrogen atom, a hydroxyl group, a sulfo group, a
carboxyl group, an amino group, an amide group, a carbamoyl group,
a nitro group, a methoxy group, an ethoxy group, a halogen group, a
phenyl group, an acetyl group, or a non-substituted or substituted
alkyl group with 1 to 4 carbon atoms. X represents a sulfo group, a
carboxyl group, or a salt thereof.
[0034] Preferable compounds represented by the general formula (1)
are N-(2-acetamido)iminodiacetic acid and
N-(2-acetamido)-2-aminoethanesulfonic acid, and
N-(2-acetamido)-2-aminoethanesulfonic acid is most preferable.
[0035] The mechanism by which the change of pH with time of the
polishing composition is suppressed by the addition of the
pH-buffering agent has not been clarified. However, when the
pH-buffering agent has a sulfo group or carboxyl group with a low
acid dissociation constant, an acid dissociation equilibrium
reaction is expected with a proton that is newly formed in the
presence of the oxidizing agent and the pH-lowering substance.
Also, it is considered that, when the pH-buffering agent is a
compound having an amide group, the ammonia that forms as a result
of hydrolysis by the oxidizing agent neutralizes the proton
mentioned above.
[0036] The content of the pH-buffering agent in the polishing
composition is preferably no less than 0.01 mmol/L, more preferably
no less than 0.1 mmol/L, even more preferably no less than 0.5
mmol/L, yet even more preferably no less than 3.0 mmol/L, and most
preferably no less than 5.0 mmol/L. An increase in the pH-buffering
agent content is desirable in that an effect of stabilizing the pH
of the polishing composition is improved.
[0037] The content of the pH-buffering agent in the polishing
composition is preferably 300 mmol/L or less, more preferably 150
mmol/L or less, even more preferably 100 mmol/L or less, and
especially preferably 50 mmol/L or less. A decrease in the
pH-buffering agent content is advantageous in that the material
cost of the polishing composition is reduced. In particular, when
the content is 50 mmol/L or less, a high polishing rate can be
maintained in addition to providing the effect of suppressing the
change of pH with time of the polishing composition.
(pH of the Polishing Composition)
[0038] The pH of the polishing composition is preferably no less
than 3, more preferably no less than 5, and even more preferably no
less than 6. As the pH increases, there is an advantage that
excessive etching of the surface of an object to be polished by the
polishing composition is made less likely to occur.
[0039] The pH of the polishing composition is preferably 9 or less
and more preferably 8 or less. As the pH decreases, there is an
advantage that scratching of the surface of an object to be
polished by the polishing composition can be suppressed.
(Polishing Accelerator)
[0040] In addition to the oxidizing agent, the pH-lowering
substance, and the pH-buffering agent, the polishing composition
may further contain a polishing accelerator that is not classified
under the above. The polishing accelerator provides an action of
chemically etching the surface of an object to be polished and
functions to improve the rate of polishing with the polishing
composition.
[0041] Examples of polishing accelerators that may be used include
inorganic acids, organic acids, and amino acids other than those
given above as examples of the pH-lowering substance and the
pH-buffering agent.
[0042] Examples of an inorganic acid include sulfuric acid, nitric
acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous
acid, and phosphoric acid.
[0043] Examples of an organic acid include formic acid, acetic
acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric
acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric
acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic
acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic
acid, salicylic acid, glyceric acid, oxalic acid, malonic acid,
succinic acid, glutaric acid, adipic acid, pimelic acid, maleic
acid, phthalic acid, malic acid, tartaric acid, citric acid, and
lactic acid. An organic sulfuric acid, such as methanesulfonic
acid, ethanesulfonic acid, and isethionic acid, may also be
used.
[0044] A salt, such as an ammonium salt and an alkali metal salt,
of an inorganic acid or an organic acid may be used, either instead
of an inorganic acid or organic acid or in combination with an
inorganic acid or organic acid. In cases where a weak acid is used
in combination with a strong base, a strong acid is used in
combination with a weak base, or a weak acid is used in combination
with a weak base, a pH-buffering action is expected.
[0045] Examples of an amino acid include glycine, .alpha.-alanine,
.beta.-alanine, N-methylglycine, N,N-dimethylglycine,
2-aminobutyric acid, norvaline, valine, leucine, norleucine,
isoleucine, phenylalanine, proline, sarcosine, ornithine, lysine,
taurine, serine, threonine, homoserine, tyrosine, bicine, tricine,
3,5-diiodo-tyrosine, .beta.-(3,4-dihydroxyphenyl)-alanine,
thyroxine, 4-hydroxy-proline, cysteine, methionine, ethionine,
lanthionine, cystathionine, cystine, cysteic acid, aspartic acid,
glutamic acid, S-(carboxymethyl)-cysteine, 4-aminobutyric acid,
asparagine, glutamine, azaserine, arginine, canavanine, citrulline,
.delta.-hydroxy-lysine, creatine, histidine, 1-methyl-histidine,
3-methyl-histidine, and tryptophan.
[0046] Among these, a polishing accelerator that is preferable from
the standpoint of a polishing rate improvement is glycine, alanine,
malic acid, tartaric acid, citric acid, glycolic acid, isethionic
acid, or an ammonium salt or alkali metal salt thereof.
[0047] The content of the polishing accelerator in the polishing
composition is preferably no less than 0.01 g/L, more preferably no
less than 0.1 g/L, and even more preferably no less than 1 g/L. As
the polishing accelerator content increases, the rate of polishing
with the polishing composition is advantageously improved.
[0048] The content of the polishing accelerator in the polishing
composition is preferably 50 g/L or less, more preferably 30 g/L or
less, and even more preferably 15 g/L or less. As the polishing
accelerator content decreases, there is an advantage that excessive
etching of the surface of an object to be polished by the oxidizing
agent is made less likely to occur.
(Surfactant)
[0049] In addition to the oxidizing agent, the pH-lowering
substance, and the pH-buffering agent, the polishing composition
may further contain a surfactant that is not classified under the
above. When the surfactant is added to the polishing composition,
in addition to recesses becoming unlikely to form at sides of a
wiring formed by polishing with the polishing composition, there is
an advantage that dishing becomes unlikely to occur on the surface
of an object after polishing with the polishing composition.
[0050] The surfactant used may be any of an anionic surfactant,
cationic surfactant, amphoteric surfactant, and nonionic
surfactant. A plurality of types of surfactants may be used in
combination and in particular, combined use of an anionic
surfactant and a nonionic surfactant is preferable from the
standpoint of suppressing recesses at sides of a wiring and
dishing.
[0051] Examples of an anionic surfactant include polyoxyethylene
alkyl sulfuric acid esters, polyoxyethylene alkyl acetic acid
esters, polyoxyethylene alkyl phosphoric acid esters, alkyl
sulfuric acid esters, polyoxyethylene alkyl sulfuric acids, alkyl
sulfuric acids, alkylbenzene sulfonic acids, alkyl phosphoric acid
esters, polyoxyethylene alkyl phosphoric acid esters,
polyoxyethylene sulfosuccinic acid, alkyl sulfosuccinic acids,
alkyl naphthalene sulfonic acids, alkyl ether sulfuric acids, and
salts thereof. These anionic surfactants are high in chemical or
physical adsorption ability to the surface of an object to be
polished and form stronger protective films on the surface of an
object to be polished. This is advantageous for improving the
flatness of the surface of an object after polishing with the
polishing composition.
[0052] Examples of a cationic surfactant include
alkyltrimethylammonium salts, alkyldimethylammonium salts,
alkylbenzyldimethylammonium salts, and alkylamine salts.
[0053] Examples of an amphoteric surfactant include alkylbetaines
and alkylamine oxides.
[0054] Examples of a nonionic surfactant include sorbitan fatty
acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid
esters, polyoxyethylene alkyl amines, and alkyl alkanol amides.
These nonionic surfactants are high in chemical or physical
adsorption ability to the surface of an object to be polished and
form stronger protective films on the surface of an object to be
polished. This is advantageous for improving the flatness of the
surface of an object after polishing with the polishing
composition.
[0055] The content of the surfactant in the polishing composition
is preferably no less than 0.001 g/L, more preferably no less than
0.005 g/L, and even more preferably no less than 0.01 g/L. As the
surfactant content increases, the flatness of the surface of an
object after polishing with the polishing composition is
advantageously improved.
[0056] the content of the surfactant in the polishing composition
is preferably 10 g/L or less, more preferably 5 g/L or less, and
even more preferably 1 g/L or less. As the surfactant content
decreases, the rate of polishing with the polishing composition is
advantageously improved.
(Metal Anticorrosive)
[0057] In addition to the oxidizing agent, the pH-lowering
substance, and the pH-buffering agent, the polishing composition
may further contain a metal anticorrosive that is not classified
under the above. As in the case where the surfactant is added, when
the metal anticorrosive is added to the polishing composition, in
addition to recesses becoming unlikely to form at sides of a wiring
formed by polishing with the polishing composition, there is an
advantage that dishing becomes unlikely to occur on the surface of
an object after polishing with the polishing composition. Also,
when an oxidizing agent is contained in the polishing composition,
the metal anticorrosive has functions of lessening the oxidation of
the surface of an object to be polished by the oxidizing agent and
of reacting with metal ions formed by oxidation of a metal at the
surface of an object to be polished to form an insoluble complex.
These functions of the metal anticorrosive improve flatness of the
surface of an object after polishing with the polishing
composition.
[0058] Although the type of metal anticorrosive used is not
restricted in particular, it is preferably a heterocyclic compound.
The number of heterocyclic rings in the heterocyclic ring is not
restricted in particular. The heterocyclic compound may be a
monocyclic compound or a polycyclic compound having a condensed
ring.
[0059] Examples of heterocyclic compounds useable as the metal
anticorrosive include nitrogen-containing heterocyclic compounds,
such as pyrrole compounds, pyrazole compounds, imidazole compounds,
triazole compounds, tetrazole compounds, pyridine compounds,
pyrazine compounds, pyridazine compounds, pyrindine compounds,
indolizine compounds, indole compounds, isoindole compounds,
indazole compounds, purine compounds, quinolizine compounds,
quinoline compounds, isoquinoline compounds, naphthyridine
compounds, phthalazine compounds, quinoxaline compounds,
quinazoline compounds, cinnoline compounds, buterizine compounds,
thiazole compounds, isothiazole compounds, oxazole compounds,
isoxazole compounds, and furazan compounds.
[0060] Examples of a pyrazole compound include 1H-pyrazole,
4-nitro-3-pyrazole carboxylic acid, and 3,5-pyrazole carboxylic
acid.
[0061] Examples of an imidazole compound include imidazole,
1-methylimidazole, 2-methylimidazole, 4-methylimidazole,
1,2-dimethylpyrazole, 2-ethyl-4-methylimidazole,
2-isopropylimidazole, benzimidazole, 5,6-dimethylbenzimidazole,
2-aminobenzimidazole, 2-chlorobenzimidazole, and
2-methylbenzimidazole.
[0062] Examples of a triazole compound include 1,2,3-triazole,
1,2,4-triazole, 1-methyl-1,2,4-triazole,
methyl-1H-1,2,4-triazole-3-carboxylate, 1,2,4-triazole-3-carboxylic
acid, methyl 1,2,4-triazole-3-carboxylate,
3-amino-1H-1,2,4-triazole, 3-amino-5-benzyl-4H-1,2,4-triazole,
3-amino-5-methyl-4H-1,2,4-triazole, 3-nitro-1,2,4-triazole,
3-bromo-5-nitro-1,2,4-triazole, 4-(1,2,4-triazole-1-yl)phenol,
4-amino-1,2,4-triazole, 4-amino-3,5-dipropyl-4H-1,2,4-triazole,
4-amino-3,5-dimethyl-4H-1,2,4-triazole,
4-amino-3,5-dipeptyl-4H-1,2,4-triazole,
5-methyl-1,2,4-triazole-3,4-diamine, 1-hydroxybenzotriazole,
1-aminobenzotriazole, 1-carboxybenzotriazole,
5-chloro-1H-benzotriazole, 5-nitro-1H-benzotriazole,
5-carboxy-1H-benzotriazole, 5,6-dimethyl-1H-benzotriazole, and
1-(1'',2'-dicarboxyethyl)benzotriazole.
[0063] Examples of a tetrazole compound include 1H-tetrazole,
5-methyltetrazole, 5-aminotetrazole, and 5-phenyltetrazole.
[0064] Examples of an indole compound include 1H-indole,
1-methyl-1H-indole, 2-methyl-1H-indole, 3-methyl-1H-indole,
4-methyl-1H-indole, 5-methyl-1H-indole, 6-methyl-1H-indole, and
7-methyl-1H-indole.
[0065] Examples of an indazole compound include 1H-indazole and
5-amino-1H-indazole.
[0066] Among these, a preferable heterocyclic compound is a
compound having a triazole skeleton and 1,2,3-triazole and
1,2,4-triazole are especially preferable. These heterocyclic
compounds are high in chemical or physical adsorption ability to
the surface of an object to be polished and form stronger
protective films on the surface of an object to be polished. This
is advantageous for improving the flatness of the surface of an
object after polishing with the polishing composition.
[0067] The content of the metal anticorrosive in the polishing
composition is preferably no less than 0.001 g/L, more preferably
no less than 0.005 g/L, and even more preferably no less than 0.01
g/L. As the metal anticorrosive content increases, the flatness of
the surface of an object after polishing with the polishing
composition is advantageously improved.
[0068] The content of the metal anticorrosive in the polishing
composition is preferably 10 g/L or less, more preferably 5 g/L or
less, and even more preferably 1 g/L or less. As the metal
anticorrosive content decreases, the rate of polishing with the
polishing composition is advantageously improved.
(Water-Soluble Polymer)
[0069] In addition to the oxidizing agent, the pH-lowering
substance, and the pH-buffering agent, the polishing composition
may further contain a water-soluble polymer that is not classified
under the above. When the water-soluble polymer is added to the
polishing composition, in addition to enabling control of the rate
of polishing with the polishing composition by adsorption of the
water-soluble polymer on the surfaces of abrasive grains or the
surface of an object to be polished, there is an advantage of
enabling stabilization of insoluble components in the polishing
composition that form during polishing.
[0070] Examples of a water-soluble polymer that may be used include
polysaccharides, such as alginic acid, pectic acid,
carboxymethylcellulose, curdlan, and pullulan; polycarboxylic acids
and salts thereof; vinyl polymers, such as polyvinyl alcohol and
polyacrolein; and polyglycerin and polyglycerin esters. Among
these, carboxymethylcellulose, pullulan, polycarboxylic acids and
salts thereof, and polyvinyl alcohol are preferable and pullulan
and polyvinyl alcohol are especially preferable.
(Abrasive Grains)
[0071] Abrasive grains have an action of mechanically polishing an
object to be polished and the addition of abrasive grains to the
polishing composition provides an advantage that the rate of
polishing with the polishing composition is improved.
[0072] The abrasive grains used may be any of inorganic particles,
organic particles, and organic/inorganic composite particles.
Examples of inorganic particles include particles made of a metal
oxide, such as silica, alumina, ceria, and titania, silicon nitride
particles, silicon carbide particles, and boron nitride particles.
Among these, silica is preferable and colloidal silica is
especially preferable. Examples of organic particles include
polymethyl methacrylate (PMMA) particles.
[0073] The abrasive grains used have an average primary particle
diameter of preferably no less than 5 nm, more preferably no less
than 7 nm, and even more preferably no less than 10 nm. As the
average primary particle diameter of the abrasive grains increases,
the rate of polishing with the polishing composition is
advantageously improved.
[0074] The abrasive grains used have an average primary particle
diameter of preferably 100 nm or less, more preferably 60 nm or
less, and even more preferably 40 nm or less. As the average
primary particle diameter of the abrasive grains decreases, there
is an advantage that dishing becomes unlikely to occur on the
surface of an object after polishing with the polishing
composition. The value of the average primary particle diameter of
the abrasive grains is calculated, for example, by the formula:
average primary particle diameter [nm]=constant/specific surface
area [m.sup.2/g] based on the specific surface area of the abrasive
grains measured by the BET method. If the abrasive grains are
silica or colloidal silica, the above constant is 2121.
[0075] The content of the abrasive grains in the polishing
composition is preferably no less than 0.005% by mass, more
preferably no less than 0.01% by mass, and even more preferably no
less than 0.05% by mass. As the abrasive grain content increases,
the rate of polishing with the polishing composition is
advantageously improved.
[0076] The content of the abrasive grains in the polishing
composition is preferably 5% by mass or less, more preferably 1% by
mass or less, and even more preferably 0.5% by mass or less. A
decrease in the abrasive grain content is advantageous in that the
material cost of the polishing composition is reduced and
additionally, in that dishing becomes unlikely to occur on the
surface of an object after polishing with the polishing
composition.
[0077] Next, a second embodiment of the present invention will now
be described.
[0078] A polishing composition of the second embodiment mainly
differs from the polishing composition of the first embodiment in
containing a pH-controlling agent in place of the pH-buffering
agent. The polishing composition of the second embodiment will now
be described below mainly in regard to this point of
difference.
(pH-Controlling Agent)
[0079] The pH-controlling agent is defined as a compound that forms
a basic substance in an aqueous solution in the presence of an
oxidizing agent. With the polishing composition of the second
embodiment, by containing the pH-lowering substance and the
pH-controlling agent, the change of pH of the polishing composition
with time can be suppressed. The lowering of polishing performance
with time of the polishing composition can thus be suppressed to a
level that does not present a problem in terms of practical use and
a polishing composition of excellent stability can be provided.
[0080] The basic substance that is formed in the presence of an
oxidizing agent may be any of ammonia, methylamine, dimethylamine,
trimethylamine, ethylamine, diethylamine, triethylamine,
ethylenediamine, diethylenetriamine, triethylenetetramine,
tetraethylenepentamine, iminobispropylamine,
dimethylaminoethylamine, dimethylaminopropylamine, and
diethylaminoethylamine, and ammonia is especially preferable since
it is low in molecular weight and rapid pH control is expected.
[0081] The pH-controlling agent is preferably a compound having an
amide group and is more preferably an amphoteric amino acid further
having at least one of a sulfo group and a carboxyl group in
addition to the amide group. The pH-controlling agent may be a
compound represented by the following general formula (2).
##STR00002##
[0082] In the general formula (2), R.sub.1 and R.sub.3 each
independently represent a non-substituted or substituted
straight-chain alkyl group with 1 to 4 carbon atoms. R.sub.2
represents a hydrogen atom, a hydroxyl group, a sulfo group, a
carboxyl group, a phosphono group, an amino group, an amide group,
a carbamoyl group, a nitro group, a methoxy group, an ethoxy group,
a halogen group, a phenyl group, an acetyl group, an acyl group, or
a non-substituted or substituted alkyl group with 1 to 4 carbon
atoms. X represents a sulfo group, a carboxyl group, or a salt
thereof.
[0083] Preferable compounds represented by the general formula (2)
are N-(2-acetamido)iminodiacetic acid and
N-(2-acetamido)-2-aminoethanesulfonic acid, and
N-(2-acetamido)-2-aminoethanesulfonic acid is most preferable.
[0084] With regard to aqueous solutions containing either of the
two compounds described above as examples of the pH-controlling
agent or an alternative compound, whether the basic substance is
formed or not was examined in the presence of and in the absence of
hydrogen peroxide and the results are shown in Table 2.
Specifically, each aqueous solution was prepared by mixing a
predetermined amount of a pH-controlling agent or an alternative
compound with water and thereafter left to stand in storage for
eight days under ordinary temperature (23.degree. C. to 27.degree.
C.) using a constant temperature bath. The results of qualitatively
and quantitatively analyzing the basic substance in each aqueous
solution immediately after preparation and the results of
qualitatively and quantitatively analyzing the basic substance in
each aqueous solution after being left to stand for eight days are
respectively indicated in the "Basic substance concentration
immediately after preparation" column and the "Basic substance
concentration after eight days" column in the "Without hydrogen
peroxide" column of Table 2. Also, 10.32 g of a 31% by weight
hydrogen peroxide solution, that is, 3.2 g of hydrogen peroxide
were added to 100 ml of each aqueous solution obtained by mixing a
predetermined amount of a pH-controlling agent or an alternative
compound with water and thereafter each aqueous solution was left
to stand in storage for eight days under ordinary temperature
(23.degree. C. to 27.degree. C.) using a constant temperature bath.
The results of qualitatively and quantitatively analyzing the basic
substance in each aqueous solution immediately after the addition
of hydrogen peroxide and the results of qualitatively and
quantitatively analyzing the basic substance in each aqueous
solution after being left to stand for the eight days are
respectively indicated in the "Basic substance concentration
immediately after preparation" column and the "Basic substance
concentration after eight days" column in the "With hydrogen
peroxide" column of Table 2. Qualitative and quantitative analyses
of the basic substance in each aqueous solution were performed by
an ion chromatography method.
TABLE-US-00002 TABLE 2 With Without hydrogen peroxide hydrogen
peroxide pH-controlling agent or alternative Basic substance Basic
substance compound concentration Basic substance concentration
Basic substance Content immediately after concentration after
immediately after concentration after Name [mM] preparation [mM]
eight days [mM] preparation [mM] eight days [mM] Example 1
N-(2-acetamido)-2- 5.0 not detected 1.54 not detected 0.03
(pH-controlling agent) aminoethanesulfonic acid (NH.sub.4)
(NH.sub.4) Example 2 N-(2-acetamido)iminodiacetic acid 5.0 not
detected 0.21 not detected 0.01 (pH-controlling agent) (NH.sub.4)
(NH.sub.4) Example 3 3-morpholinopropane sulfonic 5.0 not detected
0.02 not detected 0.01 acid (NH.sub.4) (NH.sub.4) Example 4
2-[4-(2-hydroxyethyl)-1- 5.0 not detected 0.02 not detected not
detected piperazinyl]ethanesulfonic acid (NH.sub.4) Example 5
acetamide 5.0 not detected 0.03 not detected not detected
(NH.sub.4) Example 6 taurine 5.0 not detected not detected not
detected not detected Example 7 phosphoric acid 5.0 not detected
not detected not detected not detected
[0085] The content of the pH-controlling agent in the polishing
composition is preferably no less than 0.01 mM, more preferably no
less than 0.1 mM, even more preferably no less than 0.5 mM, yet
even more preferably no less than 3.0 mM, and most preferably no
less than 5.0 mM. An increase in the pH-controlling agent content
is desirable in that the effect of stabilizing the pH of the
polishing composition is improved.
[0086] The content of the pH-controlling agent content in the
polishing composition is preferably 300 mM or less, more preferably
150 mM or less, even more preferably 100 mM or less, and especially
preferably 50 mM or less. A decrease in the pH-controlling agent
content is advantageous in that the material cost of the polishing
composition is reduced. In particular, when the content is 50 mM or
less, a high polishing rate can be maintained in addition to
providing the effect of suppressing the change of pH with time of
the polishing composition.
[0087] The first and second embodiments may be changed as follows.
[0088] The polishing composition according to each of the
embodiments may further contain a known additive such as a
preservative and a fungicide, as necessary. Examples of
preservatives and fungicides include isothiazoline-based
preservatives, such as 2-methyl-4-isothiazoline-3-one and
5-chloro-2-methyl-4-isothiazoline-3-one, and paraoxybenzoate
esters, and phenoxyethanol. [0089] The polishing composition
according to each of the embodiments may be a one-component
composition or may be a multi-component composition as a
two-component composition. [0090] The polishing composition
according to each of the embodiments may be prepared by diluting a
stock solution of the polishing composition, for example, ten-fold
or more with a diluent such as water. [0091] The polishing
composition according to each of the embodiments may be used in
applications other than polishing during LSI manufacture.
[0092] Next, working examples and comparative examples of the
present invention will be described.
Working Examples 1 to 9 and Comparative Examples 1 to 5
[0093] Polishing compositions of Working Examples 1 to 9 were
respectively prepared by mixing an oxidizing agent, a pH-lowering
substance, a pH-buffering agent, a polishing accelerator, a
surfactant, and abrasive grains in water. Polishing compositions of
Comparative Examples 1 to 5 were respectively prepared by mixing an
oxidizing agent, a pH-lowering substance, an alternative compound
to a pH-buffering agent, a polishing accelerator, a surfactant, and
abrasive grains in water. Details of the pH-buffering agent or
alternative compound to a pH-buffering agent in the polishing
composition of each of Working Examples 1 to 9 and Comparative
Examples 1 to 5 are as indicated in the "Name" column and "Content"
column in the "pH-buffering agent or alternative compound" column
of Table 3. Although not indicated in Table 3, the polishing
composition of each of Working Examples 1 to 9 and Comparative
Examples 1 to 5 contained 51.6 g/L of a 31% by weight hydrogen
peroxide solution (that is, 16 g/L of hydrogen peroxide) as the
oxidizing agent, 0.5 g/L of a polyoxyethylene alkyl ether and 0.15
g/L of a 1:1 mixture of
1-[N,N-bis(hydroxyethyl)aminomethyl]-5-methylbenzotriazole and
1-[N,N-bis(hydroxyethyl)aminomethyl]-4-methylbenzotriazole as the
pH-lowering substance, 10 g/L of glycine as the polishing
accelerator, 0.3 g/L of ammonium lauryl ether sulfate as the
surfactant, and 0.1% by mass of colloidal silica with an average
primary particle diameter of 30 nm as determined by the BET method
as the abrasive grains. All of the polishing compositions were
adjusted to a pH of approximately 7.5 using potassium
hydroxide.
TABLE-US-00003 TABLE 3 With hydrogen peroxide pH-buffering agent or
alternative pH compound immediately Without hydrogen peroxide
Content after pH after pH change pH immediately pH after pH change
Name [mmol/L] preparation eight days amount after preparation eight
days amount Working N-(2-acetamido)-2- 0.1 7.49 7.30 -0.19 7.48
7.47 -0.01 Example 1 aminoethanesulfonic acid Working
N-(2-acetamido)-2- 0.5 7.50 7.35 -0.15 7.48 7.47 -0.01 Example 2
aminoethanesulfonic acid Working N-(2-acetamido)-2- 1.0 7.49 7.40
-0.09 7.47 7.47 0.00 Example 3 aminoethanesulfonic acid Working
N-(2-acetamido)-2- 3.0 7.47 7.40 -0.07 7.48 7.47 -0.01 Example 4
aminoethanesulfonic acid Working N-(2-acetamido)-2- 5.0 7.47 7.47
0.00 7.46 7.45 -0.01 Example 5 aminoethanesulfonic acid Working
N-(2-acetamido)-2- 10 7.47 7.47 0.00 7.46 7.45 -0.01 Example 6
aminoethanesulfonic acid Working N-(2-acetamido)-2- 25 7.47 7.47
0.00 7.46 7.45 -0.01 Example 7 aminoethanesulfonic acid Working
N-(2-acetamido)-2- 50 7.47 7.47 0.00 7.46 7.45 -0.01 Example 8
aminoethanesulfonic acid Working N-(2-acetamido)iminodiacetic 5.0
7.41 6.95 -0.46 7.45 7.43 -0.02 Example 9 acid Comparative none 5.0
7.55 6.49 -1.06 7.44 7.41 -0.03 Example 1 Comparative
3-morpholinopropanesulfonic 5.0 7.47 5.85 -1.62 7.50 7.45 -0.05
Example 2 acid Comparative acetamide 5.0 7.50 6.47 -1.03 7.20 7.26
0.06 Example 3 Comparative taurine 5.0 7.55 6.53 -1.02 7.9 7.17
-0.02 Example 4 Comparative phosphoric acid 5.0 7.50 6.88 -0.62
7.50 7.47 -0.03 Example 5 High-pressure polishing conditions
Polishing Low-pressure polishing conditions rate immediately
Polishing rate Polishing rate Percentage after preparation
Polishing rate after Percentage change of immediately after after
eight change of [nm/min] eight days [nm/min] polishing rate [%]
preparation [nm/min] days [nm/min] polishing rate [%] Working 714
734 2.8 342 354 3.5 Example 1 Working 713 723 1.4 342 348 1.8
Example 2 Working 703 713 1.4 332 335 0.9 Example 3 Working 700 703
0.4 333 335 0.6 Example 4 Working 696 695 -0.1 333 334 0.3 Example
5 Working 695 696 0.1 333 334 0.3 Example 6 Working 687 688 0.1 341
341 0.0 Example 7 Working 515 516 0.2 256 256 0.0 Example 8 Working
453 474 4.6 189 195 3.2 Example 9 Comparative 679 740 9.0 320 396
23.8 Example 1 Comparative 705 804 14.0 329 391 18.8 Example 2
Comparative 560 725 29.5 286 404 41.3 Example 3 Comparative 628 757
20.5 329 407 23.7 Example 4 Comparative 432 522 20.8 256 336 31.3
Example 5
<pH>
[0094] The polishing compositions of Working Examples 1 to 9 and
Comparative Examples 1 to 5 were left to stand in storage for eight
days under ordinary temperature (23.degree. C. to 27.degree. C.)
using a constant temperature bath. The pH value of each polishing
composition measured immediately after preparation, the pH value of
each polishing composition measured after being left to stand for
eight days, and the amount of change of pH that occurred within
eight days are respectively indicated in the "pH immediately after
preparation" column, the "pH after eight days" column, and the "pH
change amount" column in the "With hydrogen peroxide" column of
Table 3.
[0095] Compositions each having a chemical makeup the same as the
chemical makeup of one of the polishing compositions of Working
Examples 1 to 9 and Comparative Examples 1 to 5 from which hydrogen
peroxide is omitted were left to stand in storage for eight days
under ordinary temperature (23.degree. C. to 27.degree. C.) using a
constant temperature bath. The pH value of each composition
measured immediately after preparation, the pH value of each
composition measured after being left to stand for eight days, and
the amount of change of pH that occurred within the eight days are
respectively indicated in the "pH immediately after preparation"
column, the "pH after eight days" column, and the "pH change
amount" column in the "Without hydrogen peroxide" column of Table
3.
[0096] All pH measurements were made under ordinary temperature
(23.degree. C. to 27.degree. C.) using a pH meter (F-52, from
Horiba, Ltd.).
<Polishing Rate>
[0097] Using the respective polishing compositions of Working
Examples 1 to 9 and Comparative Examples 1 to 5 immediately after
preparation or after leaving to stand for eight days, the surface
of a copper blanket wafer was polished for 60 seconds under the
first polishing conditions indicated in Table 4. The polishing rate
obtained with each polishing composition immediately after
preparation, the polishing rate obtained with each polishing
composition after leaving to stand for eight days, and the
percentage change of the polishing rate that occurred by eight days
of leaving to stand are respectively indicated in the "Polishing
rate immediately after preparation" column, the "Polishing rate
after eight days" column, and the "Percentage change of polishing
rate" column in the "High-pressure polishing conditions" column of
Table 3.
[0098] Using the respective polishing compositions of Working
Examples 1 to 9 and Comparative Examples 1 to 5 immediately after
preparation or after leaving to stand for eight days, the surface
of a copper blanket wafer was polished for 60 seconds under the
second polishing conditions indicated in Table 5. The polishing
rate obtained with each polishing composition immediately after
preparation, the polishing rate obtained with each polishing
composition after leaving to stand for eight days, and the
percentage change of the polishing rate that occurred by eight days
of leaving to stand are respectively indicated in the "Polishing
rate immediately after preparation" column, the "Polishing rate
after eight days" column, and the "Percentage change of polishing
rate" column in the "Low-pressure polishing conditions" column of
Table 3.
[0099] All polishing rate values were determined by dividing the
difference in thickness of the copper blanket wafer before and
after polishing as measured using the sheet resistance meter
VR-120/08SD (from Hitachi Kokusai Electric Inc.) by the polishing
time. The values of the percentage change of polishing rate were
determined according to the following formula.
Percentage change of polishing rate (%)=(Polishing rate after eight
days-Polishing rate immediately after preparation)/Polishing rate
immediately after preparation.times.100
TABLE-US-00004 TABLE 4 <First Polishing Conditions> Polishing
machine: Single-side CMP polishing machine (Reflexion LK, from
Applied Materials, Inc.) Polishing pad: Polyurethane foam pad
Polishing pressure: 2.7 psi (=approx. 18.6 kPa) Rotational speed of
surface plate: 90 rpm Feed rate of polishing composition: 300
mL/min Rotational speed of carrier: 90 rpm
TABLE-US-00005 TABLE 5 <Second Polishing Conditions>
Polishing machine: Single-side CMP polishing machine (Reflexion LK,
from Applied Materials, Inc.) Polishing pad: Polyurethane foam pad
Polishing pressure: 1.5 psi (=approx. 10.3 kPa) Rotational speed of
surface plate: 90 rpm Feed rate of polishing composition: 300
mL/min Rotational speed of carrier: 90 rpm
[0100] As shown in the "With hydrogen peroxide" column of Table 3,
with each of the polishing compositions of Comparative Examples 1
to 5, the amount of pH change upon leaving to stand for eight days
exceeded 0.5 in absolute value. On the other hand, with each of the
polishing compositions of Working Examples 1 to 9, the amount of pH
change upon leaving to stand for eight days was 0.5 or less in
absolute value. As shown in the "High-pressure polishing
conditions" column and the "Low-pressure polishing conditions"
column of Table 3, the percentage change of polishing rate of each
of the polishing compositions of Working Examples 1 to 9 was +5% or
less and satisfactory. These results suggest that the polishing
performance of a polishing composition is stabilized by preventing
the change with time of the pH of the polishing composition.
[0101] A comparison of the results of Working Example 5 and Working
Example 9 revealed that the amount of pH change and the percentage
change of polishing rate are smaller when
N-(2-acetamido)-2-aminoethanesulfonic acid is used than when
N-(2-acetamido)-iminodiacetic acid is used. Further, a comparison
of the results of Working Examples 1 to 7 revealed that by using
N-(2-acetamido)-2-aminoethanesulfonic acid at a content of no less
than 0.5 mmol/L, the percentage change of polishing rate is
suppressed to +2% or less and the polishing performance is
extremely stable.
Working Examples 11 to 21 and Comparative Examples 11 to 17
[0102] Polishing compositions of Working Examples 11 to 21 were
respectively prepared by mixing an oxidizing agent, a pH-lowering
substance, a pH-controlling agent, a polishing accelerator, a
surfactant, and abrasive grains in water. Polishing compositions of
Comparative Examples 11 to 17 were respectively prepared by mixing
an oxidizing agent, a pH-lowering substance, an alternative
compound to a pH-controlling agent, a polishing accelerator, a
surfactant, and abrasive grains in water. Details of the
pH-controlling agent or the alternative compound to a
pH-controlling agent in the polishing composition of each of
Working Examples 11 to 21 and Comparative Examples 11 to 17 are as
indicated in the "Name" columns and "Content" columns in the
"pH-controlling agent or alternative compound" columns of Tables 6
and 7. Although not indicated in Tables 6 and 7, the polishing
composition of each of Working Examples 11 to 21 and Comparative
Examples 11 to 17 contained 51.6 g/L of a 31% by weight hydrogen
peroxide solution (that is, 16 g/L of hydrogen peroxide) as the
oxidizing agent, 0.5 g/L of a polyoxyethylene alkyl ether and 0.15
g/L of a 1:1 mixture of
1-[N,N-bis(hydroxyethyl)aminomethyl]-5-methylbenzotriazole and
1-[N,N-bis(hydroxyethyl)aminomethyl]-4-methylbenzotriazole as the
pH-lowering substance, 10 g/L of glycine as the polishing
accelerator, 0.3 g/L of ammonium lauryl ether sulfate as the
surfactant, and 0.1% by mass of colloidal silica with an average
primary particle diameter of 30 nm as determined by the BET method
as the abrasive grains. All of the polishing compositions were
adjusted to a pH of approximately 7.5 using potassium
hydroxide.
TABLE-US-00006 TABLE 6 With hydrogen Without hydrogen peroxide
peroxide pH pH pH pH-controlling agent or immediately pH
immediately after pH alternative compound after pH after change
after eight change Name Content [mM] preparation eight days amount
preparation days amount Working N-(2-acetamido)-2- 0.5 7.50 7.25
-0.25 7.48 7.47 -0.01 Example 11 aminoethanesulfonic acid Working
N-(2-acetamido)-2- 1.0 7.49 7.38 -0.11 7.47 7.47 0.00 Example 12
aminoethanesulfonic acid Working N-(2-acetamido)-2- 3.0 7.47 7.40
-0.07 7.48 7.47 -0.01 Example 13 aminoethanesulfonic acid Working
N-(2-acetamido)-2- 5.0 7.47 7.46 0.01 7.46 7.45 -0.01 Example 14
aminoethanesulfonic acid Working N-(2-acetamido)-2- 10 7.47 7.47
0.00 7.46 7.45 -0.01 Example 15 aminoethanesulfonic acid Working
N-(2-acetamido)-2- 25 7.47 7.47 0.00 7.46 7.45 -0.01 Example 16
aminoethanesulfonic acid Working N-(2-acetamido)-2- 50 7.48 7.47
0.01 7.46 7.45 -0.01 Example 17 aminoethanesulfonic acid Working
N-(2-acetamido)iminodiacetic 5.0 7.41 6.95 -0.46 7.45 7.43 -0.02
Example 18 acid Working N-(2-acetamido)iminodiacetic 10 7.48 7.47
-0.01 7.49 7.48 -0.01 Example 19 acid Working
N-(2-acetamido)iminodiacetic 25 7.50 7.50 0.00 7.47 7.48 0.01
Example 20 acid Working N-(2-acetamido)iminodiacetic 50 7.49 7.48
-0.01 7.48 7.46 -0.02 Example 21 acid High-pressure Low-pressure
polishing polishing conditions conditions Polishing rate Polishing
rate immediately Polishing Percentage immediately Polishing after
rate after change of after rate after Percentage Amount of increase
in preparation eight days polishing preparation eight days change
of basic substance [nm/min] [nm/min] rate [%] [nm/min] [nm/min]
polishing rate [%] concentration [mM] Working 713 743 4.0 342 358
4.5 0.16 Example 11 (NH.sub.4) Working 703 713 1.4 332 335 0.9 0.31
Example 12 (NH.sub.4) Working 700 703 0.4 333 335 0.6 0.90 Example
13 (NH.sub.4) Working 696 695 -0.1 334 336 0.6 1.53 Example 14
(NH.sub.4) Working 695 696 0.1 333 334 0.3 2.54 Example 15
(NH.sub.4) Working 687 688 0.1 341 341 0.0 3.54 Example 16
(NH.sub.4) Working 515 516 0.2 256 256 0.0 4.54 Example 17
(NH.sub.4) Working 453 474 4.4 189 195 3.1 0.21 Example 18
(NH.sub.4) Working 453 454 0.2 189 190 0.5 0.43 Example 19
(NH.sub.4) Working 453 455 0.4 189 190 0.5 1.07 Example 20
(NH.sub.4) Working 453 452 -0.2 189 189 0.0 1.99 Example 21
(NH.sub.4)
TABLE-US-00007 TABLE 7 With hydrogen Without hydrogen peroxide
peroxide pH pH pH pH-controlling agent or immediately pH
immediately after pH alternative compound after pH after change
after eight change Name Content [mM] preparation eight days amount
preparation days amount Comparative none -- 7.55 6.49 -1.06 7.44
7.41 -0.03 Example 11 Comparative N-(2-acetamido)-2- 0.5 7.50 6.49
-1.01 7.44 7.41 -0.03 Example 12 aminoethanesulfonic acid
Comparative 3-morpholinopropanesulfonic 5.0 7.47 5.85 -1.62 7.50
7.45 -0.05 Example 13 acid Comparative 2-[4-(2-hydroxyethyl)-1- 5.0
7.50 6.74 -0.76 7.50 7.45 -0.05 Example 14
piperazinyl]ethanesulfonic acid Comparative acetamide 5.0 7.50 6.47
-1.03 7.20 7.26 0.06 Example 15 Comparative taurine 5.0 7.55 6.53
-1.02 7.19 7.17 -0.02 Example 16 Comparative phosphoric acid 5.0
7.50 6.88 -0.62 7.50 7.47 -0.03 Example 17 High-pressure
Low-pressure polishing polishing conditions conditions Polishing
rate Polishing rate immediately Polishing Percentage immediately
Polishing after rate after change of after rate after Percentage
Amount of increase in preparation eight days polishing preparation
eight days change of basic substance [nm/min] [nm/min] rate [%]
[nm/min] [nm/min] polishing rate [%] concentration [mM] Comparative
679 740 8.2 320 396 19.2 not Example 11 detected Comparative 453
482 6.0 189 206 8.3 0.02 Example 12 (NH.sub.4) Comparative 705 804
12.3 329 391 15.9 0.02 Example 13 (NH.sub.4) Comparative 702 808
13.1 326 387 15.8 0.02 Example 14 (NH.sub.4) Comparative 560 725
22.8 286 404 29.2 0.03 Example 15 (NH.sub.4) Comparative 628 757
17.0 329 407 19.2 not Example 16 detected Comparative 432 522 17.2
256 336 23.8 not Example 17 detected
<pH>
[0103] The polishing compositions of Working Examples 11 to 21 and
Comparative Examples 11 to 17 were left to stand in storage for
eight days under ordinary temperature (23.degree. C. to 27.degree.
C.) using a constant temperature bath. The pH value of each
polishing composition measured immediately after preparation, the
pH value of each polishing composition measured after being left to
stand for eight days, and the amount of change of pH that occurred
within eight days are respectively indicated in the "pH immediately
after preparation" columns, the "pH after eight days" columns, and
the "pH change amount" columns in the "With hydrogen peroxide"
columns of Tables 6 and 7.
[0104] Compositions each having a chemical makeup the same as the
chemical makeup of one of the polishing compositions of Working
Examples 11 to 21 and Comparative Examples 11 to 17 from which
hydrogen peroxide is omitted were left to stand in storage for
eight days under ordinary temperature (23.degree. C. to 27.degree.
C.) using a constant temperature bath. The pH value of each
composition measured immediately after preparation, the pH value of
each composition measured after being left to stand for eight days,
and the amount of change of pH that occurred within the eight days
are respectively indicated in the "pH immediately after
preparation" columns, the "pH after eight days" columns, and the
"pH change amount" columns in the "Without hydrogen peroxide"
columns of Tables 6 and 7.
[0105] All pH measurements were made under ordinary temperature
(23.degree. C. to 27.degree. C.) using a pH meter (F-52, from
Horiba, Ltd.).
<Polishing Rate>
[0106] Using the respective polishing compositions of Working
Examples 11 to 21 and Comparative Examples 11 to 17 immediately
after preparation or after leaving to stand for eight days, the
surface of a copper blanket wafer was polished under the third
polishing conditions indicated in Table 8. The polishing rate
obtained with each polishing composition immediately after
preparation, the polishing rate obtained with each polishing
composition after leaving to stand for eight days, and the
percentage change of the polishing rate that occurred by eight days
of leaving to stand are respectively indicated in the "Polishing
rate immediately after preparation" columns, the "Polishing rate
after eight days" columns, and the "Percentage change of polishing
rate" columns in the "High-pressure polishing conditions" columns
of Tables 6 and 7.
[0107] Using the respective polishing compositions of Working
Examples 11 to 21 and Comparative Examples 11 to 17 immediately
after preparation or after leaving to stand for eight days, the
surface of a copper blanket wafer was polished under the fourth
polishing conditions indicated in Table 9. The polishing rate
obtained with each polishing composition immediately after
preparation, the polishing rate obtained with each polishing
composition after leaving to stand for eight days, and the
percentage change of the polishing rate that occurred by eight days
of leaving to stand are respectively indicated in the "Polishing
rate immediately after preparation" columns, the "Polishing rate
after eight days" columns, and the "Percentage change of polishing
rate" columns in the "Low-pressure polishing conditions" columns of
Tables 6 and 7.
[0108] All polishing rate values were determined by dividing the
difference in thickness of the copper blanket wafer before and
after polishing as determined by measurement of the sheet
resistance using the DC four-probe method by the polishing time.
The values of the percentage change of polishing rate were
determined according to the following formula.
Percentage change of polishing rate (%)=(Polishing rate after eight
days-Polishing rate immediately after preparation)/Polishing rate
immediately after preparation.times.100
TABLE-US-00008 TABLE 8 <Third Polishing Conditions> Polishing
machine: Single-side CMP polishing machine Polishing pad:
Polyurethane foam pad Polishing pressure: 2.7 psi (=approx. 18.6
kPa) Rotational speed of surface plate: 90 rpm Feeding of polishing
composition: Continuously fed without being circulated Rotational
speed of carrier: 90 rpm
TABLE-US-00009 TABLE 9 <Fourth Polishing Conditions>
Polishing machine: Single-side CMP polishing machine Polishing pad:
Shooting polyurethane pad Polishing pressure: 1.2 psi (=approx. 8.3
kPa) Rotational speed of surface plate: 90 rpm Feeding of polishing
composition: Continuously fed without being circulated Rotation
speed of carrier: 90 rpm
<Amount of Increase in Basic Substance>
[0109] With each of the polishing compositions of Working Examples
11 to 21 and Comparative Examples 11 to 17, the concentration of
basic substance in the polishing composition immediately after
preparation and the concentration of basic substance in the
polishing composition after leaving to stand for eight days were
measured. The concentration differences are indicated in the
"Amount of increase in basic substance concentration" columns of
Tables 6 and 7. Qualitative and quantitative analyses of the basic
substance in the respective polishing compositions were performed
by the ion chromatography analysis method.
[0110] As shown in the "With hydrogen peroxide" column of Table 7,
with each of the polishing compositions of Comparative Examples 11
to 17, the amount of pH change upon leaving to stand for eight days
exceeded 0.5 in absolute value. On the other hand, as shown in the
"With hydrogen peroxide" column of Table 6, with each of the
polishing compositions of Working Examples 11 to 21, the amount of
pH change upon leaving to stand for eight days was 0.5 or less in
absolute value. As shown in the "High-pressure polishing
conditions" column and the "Low-pressure polishing conditions"
column of Table 6, the percentage change of polishing rate of each
of the polishing compositions of Working Examples 11 to 21 was +50
or less and satisfactory. These results suggest that the polishing
performance of a polishing composition is stabilized by preventing
the change with time of the pH of the polishing composition.
[0111] A comparison of the results of Working Examples 19 to 21 and
Comparative Example 12 revealed a trend such that the greater the
amount of an increase in concentration of the basic substance, the
less the amount of pH change and percentage change of polishing
rate.
[0112] A comparison of the results of Working Example 14 to 17 and
Working Examples 18 to 21 revealed that the amount of pH change and
the percentage change of polishing rate are smaller when
N-(2-acetamido)-2-aminoethanesulfonic acid is used than when
N-(2-acetamido)-iminodiacetic acid is used.
* * * * *