U.S. patent application number 11/508893 was filed with the patent office on 2007-03-01 for aqueous dispersion for chemical mechanical polishing, kit for preparing the aqueous dispersion, chemical mechanical polishing process, and process for producing semiconductor devices.
This patent application is currently assigned to JSR Corporation. Invention is credited to Dai Fukushima, Masayuki Hattori, Nobuyuki Kurashima, Gaku Minamihaba, Hirotaka Shida, Akihiro Takemura, Yoshikuni Tateyama, Susumu Yamamoto, Hiroyuki Yano.
Application Number | 20070049180 11/508893 |
Document ID | / |
Family ID | 37258100 |
Filed Date | 2007-03-01 |
United States Patent
Application |
20070049180 |
Kind Code |
A1 |
Shida; Hirotaka ; et
al. |
March 1, 2007 |
Aqueous dispersion for chemical mechanical polishing, kit for
preparing the aqueous dispersion, chemical mechanical polishing
process, and process for producing semiconductor devices
Abstract
An aqueous dispersion for chemical mechanical polishing contains
water, a polyvinylpyrrolidone having a weight-average molecular
weight exceeding 200,000, an oxidant, a protective film-forming
agent and abrasive grains, the protective film-forming agent
containing a first metal compound-forming agent which forms a
water-insoluble metal compound, and a second metal compound-forming
agent which forms a water-soluble metal compound. The aqueous
dispersion is capable of uniformly and stably polishing a metal
film at low friction without causing defects in a metal film and an
insulating film.
Inventors: |
Shida; Hirotaka; (Tokyo,
JP) ; Takemura; Akihiro; (Tokyo, JP) ;
Hattori; Masayuki; (Yatomi-shi, JP) ; Minamihaba;
Gaku; (Yokohama-shi, JP) ; Fukushima; Dai;
(Kamakura-shi, JP) ; Kurashima; Nobuyuki;
(Yokohama-shi, JP) ; Yamamoto; Susumu; (Oita-shi,
JP) ; Tateyama; Yoshikuni; (Hiratsuka-shi, JP)
; Yano; Hiroyuki; (Yokohama-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
JSR Corporation
Chuo-ku
JP
KABUSHIKI KAISHA TOSHIBA
Minato-ku
JP
|
Family ID: |
37258100 |
Appl. No.: |
11/508893 |
Filed: |
August 24, 2006 |
Current U.S.
Class: |
451/41 ;
257/E21.304; 257/E21.583 |
Current CPC
Class: |
H01L 21/7684 20130101;
B24B 37/044 20130101; H01L 21/76835 20130101; H01L 21/3212
20130101; C09G 1/02 20130101 |
Class at
Publication: |
451/041 |
International
Class: |
B24B 7/30 20060101
B24B007/30 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 24, 2005 |
JP |
2005-242895 |
Claims
1. An aqueous dispersion for chemical mechanical polishing,
comprising water, a polyvinylpyrrolidone having a weight-average
molecular weight exceeding 200,000, an oxidant, a protective
film-forming agent and abrasive grains, the protective film-forming
agent comprising a first metal compound-forming agent which forms a
water-insoluble metal compound, and a second metal compound-forming
agent which forms a water-soluble metal compound.
2. The aqueous dispersion for chemical mechanical polishing
according to claim 1, wherein the water-insoluble metal compound is
a water-insoluble complex.
3. The aqueous dispersion for chemical mechanical polishing
according to claim 1, wherein the water-soluble metal compound is a
water-soluble complex.
4. The aqueous dispersion for chemical mechanical polishing
according to claim 1, wherein the polyvinylpyrrolidone has a K
value exceeding 57 as determined by the Fikentscher method.
5. The aqueous dispersion for chemical mechanical polishing
according to claim 1, which has a viscosity of less than 2
mPaa.
6. The aqueous dispersion for chemical mechanical polishing
according to claim 1, further comprising a surface active
agent.
7. The aqueous dispersion for chemical mechanical polishing
according to claim 1, wherein the abrasive grains have an average
particle size of 5 to 1000 nm.
8. The aqueous dispersion for chemical mechanical polishing
according to claim 1, wherein the content of the
polyvinylpyrrolidone is from 0.001 to 0.5% by weight of the aqueous
dispersion.
9. The aqueous dispersion for chemical mechanical polishing
according to claim 1, wherein the content of the oxidant is from
0.05 to 5% by weight of the aqueous dispersion.
10. The aqueous dispersion for chemical mechanical polishing
according to claim 1, wherein the content of the protective
film-forming agent is from 0.001 to 3.0% by weight of the aqueous
dispersion.
11. The aqueous dispersion for chemical mechanical polishing
according to claim 1, wherein the content of the first metal
compound-forming agent is from 0.0005 to 2.0% by weight of the
aqueous dispersion.
12. The aqueous dispersion for chemical mechanical polishing
according to claim 1, wherein the content of the second metal
compound-forming agent is from 0.0005 to 2.0% by weight of the
aqueous dispersion.
13. The aqueous dispersion for chemical mechanical polishing
according to claim 1, wherein the content of the abrasive grains is
from 0.01 to 5% by weight of the aqueous dispersion.
14. The aqueous dispersion for chemical mechanical polishing
according to claim 6, wherein the content of surface active agent
is from 0.001 to 0.5% by weight of the aqueous dispersion.
15. A chemical mechanical polishing process comprising: a step of
bringing a semiconductor substrate having a metal film into contact
with a polishing pad attached to a turntable; and a step of
polishing a surface of the metal film while dropping the aqueous
dispersion of claim ion the polishing pad.
16. A process for producing semiconductor devices, comprising: a
step of forming an insulating film on a semiconductor substrate; a
step of forming a concave groove in the insulating film; a step of
depositing a metal in the concave groove and on the insulating film
to form a metal film; and a step of removing at least part of the
metal film deposited on the insulating film by chemical mechanical
polishing using the aqueous dispersion of claim 1.
17. A kit for preparing an aqueous dispersion for chemical
mechanical polishing, the kit comprising a liquid (I) and a liquid
(II), the liquids being mixed to give the aqueous dispersion of
claim 1, wherein the liquid (I) is an aqueous dispersion containing
water, the polyvinylpyrrolidone, the protective film-forming agent
and the abrasive grains, and the liquid (II) contains water and the
oxidant.
18. A kit for preparing an aqueous dispersion for chemical
mechanical polishing, the kit comprising a liquid (III) and a
liquid (IV), the liquids being mixed to give the aqueous dispersion
of claim 1, wherein the liquid (III) is an aqueous dispersion
containing water and the abrasive grains, the liquid (IV) contains
water and the protective film-forming agent, the liquid (III)
and/or the liquid (IV) contain the polyvinylpyrrolidone, and the
liquid (III) and/or the liquid (IV) contain the oxidant.
19. A kit for preparing an aqueous dispersion for chemical
mechanical polishing, the kit comprising a liquid (V), a liquid
(VI) and a liquid (VII), the liquids being mixed to give the
aqueous dispersion of claim 1, wherein the liquid (V) is an aqueous
dispersion containing water and the abrasive grains, the liquid
(VI) contains water and the protective film-forming agent, the
liquid (VII) containing water and the oxidant, and at least one of
the liquids (V), (VI) and (VII) contain the polyvinylpyrrolidone.
Description
TECHNICAL FIELD
[0001] The present invention relates to an aqueous dispersion for
chemical mechanical polishing, a chemical mechanical polishing
process, and a process for producing semiconductor devices. More
particularly, the invention relates to an aqueous dispersion for
chemical mechanical polishing of metal films, a kit for preparing
the aqueous dispersion, a process for chemically mechanically
polishing metal films, and a process for producing semiconductor
devices having damascene wirings.
BACKGROUND ART
[0002] Cu damascene wirings on high-performance LSI are formed by
using Chemical mechanical polishing (CMP). CMP performs first
polishing which polishes mainly Cu, and second polishing which
polishes extra metals and insulating film. It is necessary that the
first polishing polish Cu at 800 nm/min and do not substantially
polish a barrier metal such as Ta or Ti while the Cu dishing should
not exceed 20 nm in depth. When the insulating film is made of a
low-k material, it will be peeled or broken by high polishing
friction. Accordingly, the use of conventional CMP aqueous
dispersions (CMP slurries) having high polishing friction is
increasingly difficult.
[0003] In the second polishing, it is necessary that Cu scratches
and corrosion and scratches on the insulating film are reduced by
polishing the surface at low friction to increase hydrophilicity of
the surface and the polishing pad as with the first polishing.
Further, the improvements of Cu dishing and erosion of the
insulating film by the second polishing are desired. However,
conventional silicone surface active agents strongly act on
abrasive grain silica to produce coarse particles, making it
difficult to prevent scratches and stabilize the removal rate.
[0004] To satisfy the requirements for the first and second
polishing as described above, slurries containing
polyvinylpyrrolidone (PVP) are proposed (for example,
JP-A-2003-282494, JP-A-2002-270549 and JP-A-2002-517593). However,
the existing slurries are incapable of preventing the Cu dishing
and Cu corrosion and scratches on the insulating film while showing
high stability in the formation of Cu damascene wiring.
Consequently, performances required for next-generation LSI are not
fully satisfied.
OBJECT OF THE INVENTION
[0005] It is an object of the invention to provide a CMP aqueous
dispersion capable of uniformly and stably polishing a metal film
at low friction without causing defects in the metal film and the
insulating film, and capable of excellent removal selectivity with
respect to a Cu film. It is another object of the invention to
provide a kit for preparing the CMP aqueous dispersion. It is a
further object of the invention to provide a process capable of
uniformly and stably polishing a metal film without causing defects
in the metal film and the insulating film, and capable of selective
CMP of a Cu film. It is another object of the invention to provide
a process for producing very reliable semiconductor devices having
damascene wirings.
DISCLOSURE OF THE INVENTION
[0006] An aqueous dispersion for chemical mechanical polishing
according to the present invention comprises water, a
polyvinylpyrrolidone having a weight-average molecular weight
exceeding 200,000, an oxidant, a protective film-forming agent and
abrasive grains, the protective film-forming agent comprising a
first metal compound-forming agent which forms a water-insoluble
metal compound, and a second metal compound-forming agent which
forms a water-soluble metal compound.
[0007] The water-insoluble metal compound is preferably a
water-insoluble complex, and the water-soluble metal compound is
preferably a water-soluble complex.
[0008] A chemical mechanical polishing process according to the
present invention comprises a step of bringing a semiconductor
substrate having a metal film into contact with a polishing pad
attached to a turntable; and a step of polishing a surface of the
metal film while dropping the above aqueous dispersion on the
polishing pad.
[0009] A process for producing semiconductor devices according to
the present invention comprises:
[0010] a step of forming an insulating film on a semiconductor
substrate;
[0011] a step of forming a concave groove in the insulating
film;
[0012] a step of depositing a metal in the concave groove and on
the insulating film to form a metal film; and
[0013] a step of removing at least part of the metal film deposited
on the insulating film by chemical mechanical polishing using the
above aqueous dispersion.
[0014] A first kit for preparing an aqueous dispersion for chemical
mechanical polishing according to the present invention comprises a
liquid (I) and a liquid (II), the liquids being mixed to give the
aforesaid aqueous dispersion, wherein the liquid (I) is an aqueous
dispersion containing water, the polyvinylpyrrolidone, the
protective film-forming agent and the abrasive grains, and the
liquid (II) contains water and the oxidant.
[0015] A second kit for preparing an aqueous dispersion for
chemical mechanical polishing according to the present invention
comprises a liquid (III) and a liquid (IV), the liquids being mixed
to give the aforesaid aqueous dispersion, wherein the liquid (III)
is an aqueous dispersion containing water and the abrasive grains,
the liquid (IV) contains water and the protective film-forming
agent, the liquid (III) and/or the liquid (IV) contain the
polyvinylpyrrolidone, and the liquid (III) and/or the liquid (IV)
contain the oxidant.
[0016] A third kit for preparing an aqueous dispersion for chemical
mechanical polishing according to the present invention comprises a
liquid (V), a liquid (VI) and a liquid (VII), the liquids being
mixed to give the aforesaid aqueous dispersion, wherein the liquid
(V) is an aqueous dispersion containing water and the abrasive
grains, the liquid (VI) contains water and the protective
film-forming agent, the liquid (VII) contains water and the
oxidant, and at least one of the liquids (V), (VI) and (VII)
contain the polyvinylpyrrolidone.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a sectional view of a semiconductor device before
chemical mechanical polishing in the process for producing
semiconductor devices of the invention;
[0018] FIG. 2 is a sectional view of the semiconductor device shown
in FIG. 1 after first chemical mechanical polishing;
[0019] FIG. 3 is a schematic view illustrating CMP;
[0020] FIG. 4 is a sectional view of the semiconductor device shown
in FIG. 1 after second chemical mechanical polishing;
[0021] FIG. 5 is a sectional view of a semiconductor device before
chemical mechanical polishing in the process for producing
semiconductor devices of the invention; and
[0022] FIG. 6 is a sectional view of the semiconductor device shown
in FIG. 5 after chemical mechanical polishing.
PREFERRED EMBODIMENTS OF THE INVENTION
CMP Aqueous Dispersion
[0023] The CMP aqueous dispersion according to the present
invention contains water, a high-molecular weight
polyvinylpyrrolidone, an oxidant, a protective film-forming agent
and abrasive grains. These components will be described below.
<Polyvinylpyrrolidone>
[0024] The polyvinylpyrrolidone (PVP) has a weight-average
molecular weight (Mw) in terms of polyethylene glycol exceeding
200,000, preferably from more than 200,000 to 1,500,000, more
preferably from 300,000 to 1,500,000, even more preferably from
500,000 to 1,200,000, particularly preferably from 650,000 to
1,100,000, as determined by aqueous GPC (gel permeation
chromatography). When the weight-average molecular weight is in
this range, the CMP aqueous dispersion shows reduced polishing
friction, prevents the dishing and corrosion of the metal film, and
can polish the metal film stably. When the weight-average molecular
weight is below the lower limit, the removal selectivity with
respect to the Cu film is often lowered. When the weight-average
molecular weight is excessively high, a practical removal rate with
respect to the metal film is not often obtained, and PVP causes
aggregation of the abrasive grains in a slurry supply apparatus and
the aggregated abrasive grains will increase scratches on Cu.
[0025] PVP preferably has a K value exceeding 57, still preferably
from more than 57 to 106, even more preferably from 65 to 106,
particularly preferably from 76 to 100, optimally from 82 to 97, as
determined by the Fikentscher method. When the K value is in this
range, the CMP aqueous dispersion shows reduced polishing friction,
prevents the dishing and corrosion of the metal film, and can
polish the metal film stably. When the K value is below the lower
limit, the removal selectivity with respect to the Cu film is often
lowered. When the K value is excessively high, a practical removal
rate with respect to the metal film is not often obtained, and PVP
causes aggregation of the abrasive grains in a slurry supply
apparatus and the aggregated abrasive grains will increase
scratches on Cu. The higher the molecular weight of PVP, the higher
the K value.
[0026] The K value may be obtained as follows. When the K value
will be less than 20, a 5% (g/100 ml) PVP solution is measured for
viscosity, and when the K value will be 20 or more, a 1% (g/100 ml)
PVP solution is measured for viscosity. The sample concentration is
based on dry weight. When the K value will be 20 or more, exactly
1.0 g of the sample is weighed in a 100-ml measuring flask and
distilled water is added at room temperature. The sample is
completely dissolved by shaking the flask, followed by adding
distilled water to make the total volume exactly 100 ml. The sample
solution is allowed to stand in a constant-temperature bath
(25.+-.0.2.degree. C.) for 30 minutes and is measured for viscosity
with an Ubbelohde viscometer. The solution is allowed to flow
between two marking lines, and the elapsed time is measured. This
measurement is repeated several times, and the average is obtained.
To determine the relative viscosity, the same measurement is
performed with distilled water. The two flowing times obtained are
corrected based on Hagenbach-Couette correction. K .times. .times.
value = 300 .times. C .times. .times. log .times. .times. Z + ( C +
1.5 .times. C .times. .times. log .times. .times. Z ) 2 + 1.5
.times. C .times. .times. log .times. .times. Z - C 0.15 .times. C
+ 0.003 .times. C 2 ##EQU1##
[0027] In the above formula, Z is a relative viscosity
(.eta..sub.rel) of a solution having a concentration C, and C is a
concentration (%: g/100 ml). The relative viscosity .eta..sub.rel
is obtained from the following formula: .eta..sub.rel=(Solution
flowing time)/(Water flowing time) (Polymerization of PVP)
[0028] PVP used in the invention may be prepared as follows. To an
aqueous vinylpyrrolidone (hereinafter, VP) solution, water-soluble
organic peroxide and sulfite are added as redox polymerization
initiators to initiate polymerization, resulting in a
vinylpyrrolidone polymer. Herein, the vinylpyrrolidone is generally
N-vinyl-2-pyrrolidone. The vinylpyrrolidone polymers include
vinylpyrrolidone homopolymers and copolymers of vinylpyrrolidones
and other monomers. The copolymers preferably include not less than
20% by weight, more preferably not less than 30% by weight of
vinylpyrrolidone units.
[0029] Examples of the other monomers include acrylic acid,
methacrylic acid, alkyl acrylates (such as methyl acrylate and
ethyl acrylate), alkyl methacrylates (such as methyl methacrylate
and ethyl methacrylate), aminoalkyl acrylates (such as
diethylaminoethyl acrylate), aminoalkyl methacrylates, monoesters
of acrylic acid and glycols, monoesters of methacrylic acid and
glycols (such as hydroxyethyl methacrylate), alkali metal salts of
acrylic acid, alkali metal salts of methacrylic acid, ammonium
acrylates, ammonium methacrylates, quaternary ammonium derivatives
of aminoalkyl acrylates, quaternary ammonium derivatives of
aminoalkyl methacrylates, quaternary ammonium compounds of
diethylaminoethyl acrylate and methyl sulfate, vinyl methyl ether,
vinyl ethyl ether, alkali metal salts of vinylsulfonic acid,
ammonium vinylsulfonate, styrenesulfonic acid, styrenesulfonates,
allylsulfonic acid, allylsulfonates, methallylsulfonic acid,
methallylsulfonates, vinyl acetate, vinyl stearate,
N-vinylimidazole, N-vinylacetamide, N-vinylformamide,
N-vinylcaprolactam, N-vinylcarbazole, acrylamides, methacrylamides,
N-alkylacrylamides, N-methylolacrylamides,
N,N-methylenebisacrylamides, glycol diacrylates, glycol
dimethacrylates, divinylbenzenes and glycol diallyl ethers.
[0030] Polymerization of VP, or copolymerization of VP and other
monomers may be performed by solution polymerization in an aqueous
medium. For example, an aqueous water-soluble organic peroxide
solution and an aqueous sulfite solution may be added to an aqueous
VP solution to initiate polymerization.
[0031] The aqueous VP solution may have a VP concentration of 10 to
60% by weight, preferably 20 to 50% by weight. When the VP
concentration is too low, the productivity will be bad and the cost
will be increased. When the concentration is too high, the solution
increases the viscosity over time during polymerization to make
stirring difficult, increasing the possibility of hindered
reaction.
[0032] Because the polymerization system is water-based and the
redox initiator reducing agent is water-soluble, the organic
peroxide is preferably soluble in water.
[0033] Examples of the water-soluble organic peroxides include all
kinds of hydroperoxides such as tert-butyl hydroperoxide, cumene
hydroperoxide, tert-hexyl hydroperoxide and p-menthane
hydroperoxide, and water-soluble peroxyesters such as tert-butyl
peroxyacetate. Tert-butyl hydroperoxide is preferable as initiator
because by-products such as tert-butanol may be easily removed by
heating or reducing the pressure.
[0034] The amount of the water-soluble organic peroxide is
preferably from 0.005 to 5% by weight, more preferably from 0.02 to
3% by weight relative to VP. When the amount of the water-soluble
organic peroxide is too small, the polymerization rate is
decreased, often resulting in bad productivity. When the amount of
the water-soluble organic peroxide is too large, the extra peroxide
remains as impurity after the polymerization to lower the quality,
and the polymer obtained will hardly have a high molecular
weight.
[0035] The water-soluble organic peroxide may be added in the form
of solid or aqueous solution.
[0036] Examples of the sulfites include ammonium salts, alkali
metal salts (such as sodium salts and potassium salts) and alkaline
earth metal salts (such as magnesium salts and calcium salts) of
sulfurous acids including sulfurous acid, thiosulfuric acid,
hyposulfurous acid and meta-sulfurous acid. Of these sulfites,
ammonium sulfite is preferable because it does not become ash and
is easily removed due to high volatility.
[0037] The amount of the sulfite is preferably from 0.005 to 10% by
weight, more preferably from 0.02 to 7% by weight relative to VP.
When the amount of the sulfite is too small, the monomer(s) will
not be polymerized at high conversion ratio and will remain
unreacted in large amounts. When the amount is too large, it is
more likely that the sulfite or sulfate (oxide of the sulfite)
remains in PVP.
[0038] The sulfite may be added in the form of aqueous solution to
the aqueous VP solution.
[0039] The molar ratio of the water-soluble organic peroxide to the
sulfite added is preferably in the range of 1:0.5 to 1:20, more
preferably 1:1 to 1:10 to minimize the remaining water-soluble
organic peroxide in PVP.
[0040] The polymerization temperature is preferably from 10 to
90.degree. C. When the polymerization temperature is too low, the
polymerization rate is low and the productivity is often
deteriorated. When the polymerization temperature is too high, the
radical concentration in the reaction system is increased and
termination reaction is accelerated. Consequently, the initiators
are not effectively used and the amounts thereof often should be
increased.
[0041] The polymerization reaction substantially completes in 0.5
to 10 hours.
[0042] The weight-average molecular weight and K value of PVP may
be increased by reducing the amounts of the water-soluble organic
peroxide and the sulfite.
[0043] Alternatively, PVP for use in the invention may be produced
as described in JP-A-2003-40911.
[0044] PVP preferably accounts for 0.001 to 0.5% by weight, more
preferably 0.005 to 0.3% by weight, particularly preferably 0.01 to
0.1% by weight of the CMP aqueous dispersion. When PVP accounts for
less than 0.001% by weight, the aqueous dispersion is often
incapable of low polishing friction and the temperature of the
polishing pad is often increased. Consequently, polishing stops
more frequently (CMP stop), and the capability of removing Cu in a
Cu overplating part is often lowered. When PVP accounts for more
than 0.5% by weight, the Cu-removal rate is often lowered, and the
CMP aqueous dispersion has too high a viscosity and is not often
supplied stably on the polishing pad. Consequently, the temperature
of the polishing pad is increased and polishing produces uneven
effects (low inplane uniformity), often resulting in varied
Cu-removal rates and Cu-dishing sizes. To avoid these problems, the
viscosity of the CMP aqueous dispersion is preferably less than 2
mPas.
[0045] When the CMP aqueous dispersion is used in chemical
mechanical polishing which polishes a wiring metal such as Cu while
leaving a barrier metal (hereinafter, first polishing), the PVP
content is preferably in the range of 0.005 to 0.5% by weight, more
preferably 0.01 to 0.3% by weight, particularly preferably 0.02 to
0.2% by weight. This PVP content achieves low friction, high
removal rate and low barrier metal-removal rate. When the PVP
content is in the above range, the Cu dishing and erosion of the
insulating film are prevented, and defects such as Cu corrosion and
scratches are reduced, and the capability of removing Cu in the Cu
overplating part is improved to increase polishing stability and
uniformity of removal rate.
[0046] When the CMP aqueous dispersion is used in chemical
mechanical polishing which polishes the barrier metal to expose an
insulating film (hereinafter, second polishing), the PVP content is
preferably in the range of 0.001 to 0.3% by weight, more preferably
0.002 to 0.2% by weight, particularly preferably 0.005 to 0.1% by
weight. This PVP content achieves low friction and prevents the Cu
dishing and erosion of the insulating film. When the PVP content is
in the above range, defects such as Cu corrosion and scratches are
reduced, and the polishing stability and uniformity of removal rate
are increased.
[0047] PVP may be used singly or in combination of two or more
kinds different in weight-average molecular weight as long as the
weight-average molecular weights and total PVP content are in the
aforesaid ranges.
<Oxidant>
[0048] The oxidants for use in the invention include ammonium
persulfate, potassium persulfate, hydrogen peroxide, ferric
nitrate, diammonium cerium nitrate, iron sulfate, ozone and
potassium periodate. The oxidants may be used singly or in
combination of two or more kinds. In view of oxidizing power,
compatibility with the protective film and handling properties,
ammonium persulfate, potassium persulfate and hydrogen peroxide are
preferred. The oxidant preferably accounts for 0.05 to 5% by
weight, more preferably 0.08 to 3% by weight of the CMP aqueous
dispersion. When the oxidant accounts for less than 0.05% by
weight, the aqueous dispersion is often incapable of sufficient
removal rate. When the oxidant accounts for more than 5% by weight,
corrosion and dishing in the metal film such as Cu film are often
increased.
<Protective Film-Forming Agent>
[0049] The protective film-forming agent contains a first metal
compound-forming agent which forms a water-insoluble metal
compound, and a second metal compound-forming agent which forms a
water-soluble metal compound. The water-insoluble metal compound is
preferably a water-insoluble complex, and the water-soluble metal
compound is preferably a water-soluble complex. As used herein, the
term water-insoluble means that the compound is not substantially
dissolved in water, and the water-insoluble metal compounds in the
invention include compounds hardly soluble in water provided that
the wet etching rate of the compound in the presence of the oxidant
is less than 3 nm/min. The water-soluble metal compounds include
compounds having a wet etching rate of 3 nm/min or more. The
protective film-forming agent preferably accounts for 0.001 to 3.0%
by weight, more preferably 0.05 to 2.0% byweight of the CMP aqueous
dispersion. When the protective film-forming agent accounts for
less than 0.001% by weight, the Cu dishing often exceeds 20 nm in
depth. When the protective film-forming agent accounts for more
than 3.0% by weight, the removal rate is often lowered.
[0050] The first metal compound-forming agent forms a
water-insoluble or hardly water-soluble metal compound,
particularly complex, with a metal such as Cu. Examples of the
first metal compound-forming agents include heterocyclic compounds
having six-membered or five-membered hetero rings containing at
least one nitrogen atom. Specific examples include quinaldinic
acid, quinolinic acid, benzotriazole, benzimidazole,
7-hydrixy-5-methyl-1,3,4-triazaindolizine, nicotinic acid and
picolinic acid.
[0051] Examples of the first metal compound-forming agents further
include anionic surface active agents capable of forming metal
compounds with a metal such as Cu. Alkylbenzenesulfonates are
preferred, with examples including potassium
dodecylbenzenesulfonate and ammonium dodecylbenzenesulfonate.
[0052] The first metal compound-forming agent preferably accounts
for 0.0005 to 2.0% by weight, more preferably 0.0075 to 1.5% by
weight of the CMP aqueous dispersion. When the first metal
compound-forming agent accounts for less than 0.0005% by weight,
the Cu dishing is often increased in size. When the first metal
compound-forming agent accounts for more than 2.0% by weight, the
aqueous dispersion is often incapable of sufficient Cu removal
rate.
[0053] The first metal compound-forming agents may be used singly
or in combination of two or more kinds.
[0054] The second metal compound-forming agent forms a
water-soluble metal compound, particularly complex, and functions
as a polishing accelerator. Examples thereof include amino acids
such as glycine, alanine and tryptophan; organic acids such as
formic acid, lactic acid, acetic acid, tartaric acid, fumaric acid,
glycolic acid, phthalic acid, maleic acid, oxalic acid, citric
acid, malic acid, malonic acid and glutaric acid; and basic salts
such as ammonia, ethylenediamine and TMAH (tetramethylammonium
hydroxide).
[0055] The second metal compound-forming agent preferably accounts
for 0.0005 to 2.0% by weight, more preferably 0.0075 to 1.5%
byweight of the CMP aqueous dispersion. When the second metal
compound-forming agent accounts for less than 0.0005% by weight,
the aqueous dispersion is often incapable of removing Cu at a
sufficiently high rate. When the second metal compound-forming
agent accounts for more than 2.0% by weight, the Cu dishing and Cu
corrosion are often increased in size.
[0056] The second metal compound-forming agents may be used singly
or in combination of two or more kinds.
<Abrasive Grains>
[0057] Preferred examples of the abrasive grains include inorganic
particles and organic-inorganic composite particles. The inorganic
particles include fumed silica, fumed alumina and fumed titania
synthesized by reacting silicon chloride, aluminum chloride or
titanium chloride with oxygen and hydrogen in a gas phase by a
fuming process; silica synthesized by hydrolysis and condensation
of metal alkoxides by a sol-gel process; and high-purity colloidal
silica synthesized by an inorganic colloid process and purification
to remove impurities.
[0058] The types and structures of the organic-inorganic composite
particles are not particularly limited as long as organic and
inorganic particles are not easily separated during polishing. For
example, the composite particles may be obtained by polycondensing
alkoxysilane, aluminum alkoxide or titanium alkoxide in the
presence of polymer particles such as polystyrene or polymethyl
methacrylate, whereby the polycondensate such as polysiloxane,
polyaluminoxane or polytitanoxane is formed on at least the surface
of the polymer particles. The polycondensate may be directly bonded
to the functional groups of the polymer particles, or may be bonded
through a silane coupling agent or the like.
[0059] Alternatively, the organic-inorganic composite particles may
be formed from the polymer particles, and silica particles, alumina
particles or titania particles. In this case, the composite
particles maybe formed such that the silica particles or the like
are on the surface of the polymer particles by means of a
polycondensate such as polysiloxane, polyaluminoxane or
polytitanoxane as a binder; or such that the functional groups of
the silica particles or the like, for example hydroxyl groups, are
chemically bonded with the functional groups of the polymer
particles.
[0060] The organic-inorganic composite particles may be composed of
organic particles and inorganic particles that have different zeta
potential charges and are bonded by static electricity in an
aqueous dispersion.
[0061] The zeta potential of the organic particles is usually
negative over the entire pH range or a wide range of pH excluding
low pH. When the organic particles have a carboxyl group or a
sulfonic acid group, the zeta potential is more frequently
negative. When the organic particles have an amino group, the zeta
potential is sometimes positive in a specific pH range.
[0062] The zeta potential of the inorganic particles is highly
dependent on pH. The inorganic particles have an isoelectric point
at which the zeta potential is 0, and the zeta potential has a
positive or negative charge below or above the pH level.
[0063] Accordingly, when specific organic and inorganic particles
are mixed at a pH at which the zeta potential charge is reversed,
the organic and inorganic particles are bonded by static
electricity to produce composite particles. Even if the zeta
potential charges are identical at a pH in the mixing, the pH may
be adjusted after the mixing to give a reversed zeta potential
charge to the organic or inorganic particles, particularly the
inorganic particles, thereby bonding the organic and inorganic
particles.
[0064] In the presence of the composite particles bonded by static
electricity, alkoxysilane, aluminum alkoxide or titanium alkoxide
may be polycondensed to form a polycondensate such as polysiloxane,
polyaluminoxane or polytitanoxane on at least the surface of the
composite particles.
[0065] The abrasive grains preferably have an average particle size
of 5 to 1000 nm. The average particle size may be determined with a
laser scattering diffraction analyzer or a transmission electron
microscope. When the average particle size is less than 5 nm, the
CMP aqueous dispersion may not achieve a sufficiently high removal
rate. Average particle sizes exceeding 1000 nm may lead to dishing
and erosion, and precipitation and separation of the abrasive
grains. Consequently, it is often difficult that the aqueous
dispersion be stable. The average particle size of the abrasive
grains is more preferably in the range of 10 to 700 nm,
particularly preferably 15 to 500 nm. When the average particle
size is in this range, the CMP aqueous dispersion has a high
removal rate, sufficiently prevents dishing and erosion, is
resistant to precipitation and separation of the particles, and is
stable.
[0066] If metal ions such as iron, nickel and zinc ions remain in
chemically mechanically polished semiconductor devices, such
residual ions frequently cause a lowered yield. In the event that
the abrasive grains contain such metal ions, the content of the
metal ions is generally not more than 10 ppm, preferably not more
than 5 ppm, more preferably not more than 3 ppm, particularly
preferably 1 ppm. It is needless to say that the abrasive grains
are preferably free of such metal ions.
[0067] The abrasive grains preferably account for 0.01 to 5% by
weight, more preferably 0.02 to 4% by weight of the CMP aqueous
dispersion. When the abrasive grains account for less than 0.01% by
weight, the aqueous dispersion often has an insufficient removal
rate. When the abrasive grains account for more than 5% by weight,
the cost will be increased and the CMP aqueous dispersion will be
unstable.
<Surface Active Agent>
[0068] The CMP aqueous dispersion may contain a nonionic surface
active agent, an anionic surface active agent or a cationic surface
active agent as required. The nonionic surface active agents
include those having a triple bond. Specific examples include
acetylene glycols, ethylene oxide adducts thereof and acetylene
alcohols. The nonionic surface active agents further include
silicone surface active agents, polyvinyl alcohols, cyclodextrin,
polyvinyl methyl ether and hydroxyethyl cellulose. The anionic
surface active agents include fatty acid soaps, sulfates and
phosphates. The cationic surface active agents include aliphatic
amine salts and aliphatic ammonium salts. The surface active agents
may be used singly or in combination of two or more kinds. Of the
above surface active agents, the nonionic surface active agents
having a lower average molecular weight than PVP are preferred.
When the aqueous dispersion contains a high-molecular compound in
addition to PVP, the removal rate may be drastically lowered and
dishing may be drastically increased in size.
[0069] The surface active agent preferably accounts for 0.001 to
0.5% by weight, more preferably 0.05 to 0.3% by weight of the CMP
aqueous dispersion. When the surface active agent content is in
this range, the Cu dishing is sufficiently prevented.
<Properties of CMP Aqueous Dispersion>
[0070] The CMP aqueous dispersion is an aqueous dispersion of the
above-described components in water. The viscosity is preferably
less than 2 mPas. The viscosity may be adjusted by controlling the
average molecular weight and content of PVP. When the viscosity of
the CMP aqueous dispersion is not less than 2 mPas, the aqueous
dispersion is not often supplied on the polishing pad stably.
Consequently, the temperature of the polishing pad is increased and
polishing produces uneven effects (low inplane uniformity), often
resulting in varied Cu-removal rates and Cu-dishing sizes.
[0071] The pH is not particularly limited and may be adjusted
appropriately as required. For example, the pH may be rendered
alkaline by adding a pH adjuster such as potassium hydroxide.
Kit for Preparing CMP Aqueous Dispersion
[0072] The CMP aqueous dispersion may be prepared by adding the
polyvinylpyrrolidone, the oxidant, the protective film-forming
agent and the abrasive grains to water. It may be used as it is in
chemical mechanical polishing. Alternatively, the CMP aqueous
dispersion containing the components in high concentrations, that
is, concentrated aqueous dispersion may be prepared and be diluted
to a desired concentration when used in chemical mechanical
polishing.
[0073] Still alternatively, as described below, a plurality of
liquids containing any of the components (for example, two or three
liquids) may be prepared and be mixed when used. In this case, the
liquids may be mixed together to give a CMP aqueous dispersion, and
the aqueous dispersion may be supplied to a CMP apparatus.
Alternatively, the liquids may be separately supplied to a CMP
apparatus and be allowed to form a CMP aqueous dispersion on a
turntable.
<First Kit>
[0074] A first kit for preparing a CMP aqueous dispersion
(hereinafter, kit) is a combination of a liquid (I) which is an
aqueous dispersion containing water, the polyvinylpyrrolidone, the
protective film-forming agent and the abrasive grains, and a liquid
(II) containing water and the oxidant. The liquids are mixed
together to give the aforesaid CMP aqueous dispersion.
[0075] The concentrations of the components in the liquids (I) and
(II) are not particularly limited as long as the CMP aqueous
dispersion obtained by mixing the liquids has the above-described
concentrations of the components. For example, the liquids (I) and
(II) may contain the components in concentrations higher than those
in the CMP aqueous dispersion, and the liquids (I) and (II) may be
diluted and be mixed to give the CMP aqueous dispersion having the
aforesaid concentrations of the components when used. Specifically,
when the liquids (I) and (II) are mixed in a weight ratio of 1:1,
the liquids (I) and (II) may contain the components in
concentrations two times as high as in the CMP aqueous dispersion.
The liquids (I) and (II) having concentrations more than two times
as high as in the CMP aqueous dispersion may be prepared, they may
be mixed in a weight ratio of 1:1, and the CMP aqueous dispersion
may be diluted with water to the aforesaid concentrations of the
components.
[0076] By separately preparing the liquids (I) and (II), the
storage stability of the aqueous dispersion, particularly the
storage stability of the liquid containing the oxidant may be
improved.
[0077] With the first kit, the method and timing of mixing the
liquids (I) and (II) are not particularly limited as long as the
liquids form the CMP aqueous dispersion in the polishing. For
example, the liquids (I) and (II) may be mixed together and the CMP
aqueous dispersion obtained may be supplied to a CMP apparatus.
Alternatively, the liquids (I) and (II) may be separately supplied
to a CMP apparatus and may be mixed together on a turntable. Still
alternatively, the liquids (I) and (II) may be separately supplied
to a CMP apparatus, and the liquids may be mixed in feed lines in
the apparatus, or may be mixed in a mixing tank provided in the CMP
apparatus. The line mixing may use a line mixer to make the aqueous
dispersion more uniform.
<Second Kit>
[0078] A second kit is a combination of a liquid (III) which is an
aqueous dispersion containing water and the abrasive grains, and a
liquid (IV) containing water and the protective film-forming agent.
The liquids are mixed together to give the aforesaid CMP aqueous
dispersion. The polyvinylpyrrolidone and the oxidant are
independently contained in either or both of the liquids (III) and
(IV).
[0079] The concentrations of the components in the liquids (III)
and (IV) are not particularly limited as long as the CMP aqueous
dispersion obtained by mixing the liquids have the above-described
concentrations of the components. For example, the liquids (III)
and (IV) may contain the components in concentrations higher than
those in the CMP aqueous dispersion, and the liquids (III) and (IV)
may be diluted and be mixed to give the CMP aqueous dispersion
having the aforesaid concentrations of the components when used.
Specifically, when the liquids (III) and (IV) are mixed in a weight
ratio of 1:1, the liquids (III) and (IV) may contain the components
in concentrations two times as high as in the CMP aqueous
dispersion. The liquids (III) and (IV) containing the components in
concentrations more than two times as high as in the CMP aqueous
dispersion may be prepared, they may be mixed in a weight ratio of
1:1, and the CMP aqueous dispersion may be diluted with water to
the aforesaid concentrations of the components.
[0080] By separately preparing the liquids (III) and (IV), the
storage stability of the aqueous dispersion may be improved.
[0081] With the second kit, the method and timing of mixing the
liquids (III) and (IV) are not particularly limited as long as the
liquids form the CMP aqueous dispersion in the polishing. For
example, the liquids (III) and (IV) may be mixed together and the
CMP aqueous dispersion obtained may be supplied to a CMP apparatus.
Alternatively, the liquids (III) and (IV) may be separately
supplied to a CMP apparatus and may be mixed together on a
turntable. Still alternatively, the liquids (III) and (IV) may be
separately supplied to a CMP apparatus, and the liquids may be
mixed in feed lines in the apparatus, or may be mixed in a mixing
tank provided in the CMP apparatus. The line mixing may use a line
mixer to make the aqueous dispersion more uniform.
<Third Kit>
[0082] A third kit is a combination of a liquid (V) which is an
aqueous dispersion containing water and the abrasive grains, a
liquid (VI) containing water and the protective film-forming agent,
and a liquid (VII) containing water and the oxidant. The liquids
are mixed together to give the aforesaid CMP aqueous dispersion. At
least one of the liquids (V), (VI) and (VII) contains the
polyvinylpyrrolidone.
[0083] The concentrations of the components in the liquids (V),
(VI) and (VII) are not particularly limited as long as the CMP
aqueous dispersion obtained by mixing the liquids have the
above-described concentrations of the components. For example, the
liquids (V), (VI) and (VII) may contain the components in
concentrations higher than those in the CMP aqueous dispersion, and
the liquids (V), (VI) and (VII) may be diluted and be mixed to give
the CMP aqueous dispersion having the aforesaid concentrations of
the components when used. Specifically, when the liquids (V), (VI)
and (VII) are mixed in a weight ratio of 1:1:1, the liquids (V),
(VI) and (VII) may contain the components in concentrations three
times as high as in the CMP aqueous dispersion. The liquids (V),
(VI) and (VII) containing the components in concentrations more
than three times as high as in the CMP aqueous dispersion may be
prepared, they may be mixed in a weight ratio of 1:1:1, and the CMP
aqueous dispersion may be diluted with water to the aforesaid
concentrations of the components.
[0084] By separately preparing the liquids (V), (VI) and (VII), the
storage stability of the aqueous dispersion, particularly the
storage stability of the liquid containing the oxidant may be
improved.
[0085] With the third kit, the method and timing of mixing the
liquids (V), (VI) and (VII) are not particularly limited as long as
the liquids form the CMP aqueous dispersion in the polishing. For
example, the liquids (V), (VI) and (VII) may be mixed together and
the CMP aqueous dispersion obtained may be supplied to a CMP
apparatus. Alternatively, the liquids (V), (VI) and (VII) may be
separately supplied to a CMP apparatus and may be mixed together on
a turntable. Still alternatively, the liquids (V), (VI) and (VII)
may be separately supplied to a CMP apparatus, and the liquids may
be mixed in feed lines in the apparatus, or may be mixed in a
mixing tank provided in the CMP apparatus. The line mixing may use
a line mixer to make the aqueous dispersion more uniform.
CMP Process and Process for Producing Semiconductor Devices
[0086] The CMP process and process for producing semiconductor
devices according to the present invention will be described in
detail with reference to the drawings. Polishing objects in the CMP
process and production process of semiconductor devices are not
limited to the structures illustrated in the drawings as long as
they are substrates having a metal film on the surface.
<Production 1 of Semiconductor Devices>
(Fabrication of Semiconductor Device Material)
[0087] As shown in FIG. 1, a semiconductor substrate 10 with
semiconductor elements (not shown) is provided. A SiO.sub.2
insulating film 11 is formed on the semiconductor substrate, and a
plug 13 is formed through a barrier metal 12. The barrier metal 12
may be TiN, and the plug 13 may be formed of W. A first
low-dielectric constant insulating film 14 and a second
low-dielectric constant insulating film 15 are sequentially formed
to produce a laminated insulating film. The first low-dielectric
constant insulating film 14 may be composed of a low-dielectric
constant insulating material having a relative dielectric constant
of less than 2.5. The first low-dielectric constant insulating
films may comprise, for example, at least one film selected from
the group consisting of films having a siloxane skeleton such as
polysiloxane, hydrogen silosesquioxane, polymethyl siloxane and
methyl silosesquioxane; films based on organic resins such as
polyarylene ether, polybenzoxazole and polybenzocyclobutene; and
porous films such as porous silica films.
[0088] The second low-dielectric constant insulating film 15
functions as a cap insulating film and may be composed of an
insulating material having a relative dielectric constant higher
than that of the first low-dielectric constant insulating film 14.
Specifically, the second low-dielectric constant insulating films
may be formed of an insulating material having a relative
dielectric constant of not less than 2.5, which comprises at least
one material selected from the group consisting of TEOS
(tetraethoxysilane), SiC, SiCH, SiCN, SiOC and SiOCH.
[0089] A wiring concave groove A is formed in the second
low-dielectric constant insulating film 15 and first low-dielectric
constant insulating film 14. A barrier metal 16 is formed over the
entire surface by depositing a Ta film by an established method,
and a Cu film 17 is deposited thereon. The barrier metal 16 and the
Cu film 17 compose a metal film 18. The wiring groove A may form a
fine wiring or a wide wiring.
(First Chemical Mechanical Polishing)
[0090] The semiconductor device material fabricated as above is
subjected to CMP to remove the Cu film 17 of the metal film 18 with
the CMP aqueous dispersion. Consequently, as shown in FIG. 2, the
surface of the barrier metal 16 is exposed and the wiring groove A
is filled with the Cu film.
[0091] The Cu film 17 is chemically mechanically polished as shown
in FIG. 3. While the CMP aqueous dispersion (slurry 27) is supplied
from a slurry supply nozzle 25 and a turntable 20 to which a
polishing pad 21 is attached is rotated, a top ring 23 holding the
semiconductor substrate 22 is brought into contact with the
turntable. FIG. 3 shows a water supply nozzle 24 and a dresser
26.
[0092] The top ring 23 may apply a polishing load in the range of
10 to 1,000 gf/cm.sup.2, preferably 30 to 500 gf/cm.sup.2. The
rotation of the turntable 20 and the top ring 23 may be in the
range of 10 to 400 rpm, preferably 30 to 150 rpm. The flow rate of
the slurry 27 from the slurry supply nozzle 25 may be in the range
of 10 to 1,000 cc/min, preferably 50 to 400 cc/min.
(Second Chemical Mechanical Polishing (Touch-Up CMP))
[0093] After the extra Cu film 17 is removed by the first chemical
mechanical polishing, the barrier metal 16 exposed on the material
surface is polished (touch-up CMP) as required with the CMP aqueous
dispersion. Consequently, the surface of the second low-dielectric
constant insulating film 15 is exposed as shown in FIG. 4.
[0094] The touch-up CMP is performed as shown in FIG. 3. While the
CMP aqueous dispersion (slurry 27) is supplied from the slurry
supply nozzle 25 and the turntable 20 to which the polishing pad 21
is attached is rotated, the top ring 23 holding the semiconductor
substrate 22 is brought into contact with the turntable.
[0095] The top ring 23 may apply a polishing load in the range of
10 to 1,000 gf/cm.sup.2, preferably 30 to 500 gf/cm.sup.2. The
rotation of the turntable 20 and the top ring 23 may be in the
range of 10 to 400 rpm, preferably 30 to 150 rpm. The flow rate of
the slurry 27 from the slurry supply nozzle 25 may be in the range
of 10 to 1,000 cc/min, preferably 50 to 400 cc/min.
<Production 2 of Semiconductor Devices>
(Fabrication of Semiconductor Device Material)
[0096] The CMP process of the invention may apply to the production
of semiconductor devices as shown in FIG. 6. This embodiment will
be described in detail with reference to FIGS. 5 and 6.
[0097] As shown in FIG. 5, a semiconductor substrate 10 with
semiconductor elements (not shown) is provided. A SiO.sub.2
insulating film 11 is formed on the semiconductor substrate, and a
concave hole B is formed. A barrier metal 12 and a plug material
film 13a are deposited thereon sequentially. The barrier metal 12
may be formed by depositing a TiN film, and the plug material film
13a may be formed by depositing a W film.
[0098] The semiconductor device material fabricated as above ifs
subjected to CMP to remove selectively a metal film 19 containing
the plug material film 13a and the barrier metal 12. Consequently,
as shown in FIG. 6, the hole B is filled with a plug 13 through the
barrier metal 12.
[0099] The metal film 19 may be chemically mechanically polished in
the same manner as the first and second CMP in <Production 1 of
semiconductor devices>.
EFFECT OF THE INVENTION
[0100] The CMP aqueous dispersion according to the present
invention is capable of uniformly and stably polishing a metal film
at low friction without causing defects in the metal film and the
insulating film and has excellent removal selectivity with respect
to a Cu film. The kits of the invention provide this CMP aqueous
dispersion. The chemical mechanical polishing process is capable of
uniformly and stably polishing a metal film at low friction without
causing defects in the metal film and the insulating film and is
capable of selective CMP of a Cu film. The process for producing
semiconductor devices produces semiconductor devices having a
damascene wiring and high reliability.
EXAMPLES
[0101] The present invention will be described by examples without
limiting the scope of the invention.
<Preparation of Aqueous Dispersions Containing Inorganic
Particles>
(1) Preparation of Aqueous Dispersion Containing Fumed Silica
Particles
[0102] 2 kg of fumed silica particles (AEROSIL No. 90 manufactured
by Japan Aerosil, average primary particle diameter: 20 nm) was
dispersed in 6.7 kg of ion exchange water with an ultrasonic
disperser. The dispersion was filtered through a 5 .mu.m filter.
Consequently, an aqueous dispersion containing fumed silica
particles was obtained. The average secondary particle diameter of
fumed silica in the aqueous dispersion was 220 nm.
(2) Preparation of Aqueous Dispersion Containing Colloidal Silica
Particles
[0103] A flask was charged with 70 parts by mass of 25% by mass
ammonia water, 40 parts by mass of ion exchange water, 170 parts by
mass of ethanol and 20 parts by mass of tetraethoxysilane. The
temperature was raised to 60.degree. C. with stirring at 180 rpm.
The stirring was performed for 2 hours at 60.degree. C., and the
liquid was cooled to room temperature. Consequently, an alcohol
dispersion of colloidal silica particles was obtained.
[0104] The alcohol was evaporated with a rotary evaporator while
maintaining the dispersion at 80.degree. C. and adding ion exchange
water. The evaporation was repeated several times, resulting in an
aqueous dispersion containing 20% by mass of colloidal silica
particles.
[0105] The colloidal silica particles in the aqueous dispersion had
an average primary particle diameter of 25 nm and an average
secondary particle diameter of 40 nm. The colloidal silica
particles in the aqueous dispersion will be referred to as C25.
[0106] Aqueous dispersions of colloidal silica particles as shown
in Table 1 were prepared as described above except that the amounts
of ammonia water, ethanol and tetraethoxysilane were changed.
TABLE-US-00001 TABLE 1 Average Colloidal silica content Average
primary secondary Colloidal in aqueous dispersion particle diameter
particle diameter silica (wt %) (nm) (nm) C15 20.0 15 25 C20 20.0
20 35 C25 20.0 25 40 C35 20.0 35 70 C40 20.0 40 75
<Preparation of Aqueous Polyvinylpyrrolidone Solution>
[0107] A 500 ml flask was charged with 60 g of degassed
N-vinyl-2-pyrrolidone and 240 g of degassed water. These were
heated to 60.degree. C. with stirring under a stream of nitrogen,
and 0.3 g of a 10% by mass aqueous sodium sulfite solution and 0.3
g of a 10% by mass aqueous t-butylhydroperoxide solution were
added, followed by stirring at 60.degree. C. for 3 hours.
Subsequently, 1.8 g of a 10% by mass aqueous sodium sulfite
solution and 1.2 g of a 10% by mass aqueous t-butylhydroperoxide
solution were added, followed by stirring for 3 hours. The reaction
mixture was diluted with ion exchange water. Consequently, a 20% by
mass aqueous polyvinylpyrrolidone solution was obtained. The
polyvinylpyrrolidone was analyzed by aqueous gel permeation
chromatography using an eluting solution containing 0.1 mol/L
aqueous NaCl solution/acetonitrile=80/20 (by volume), resulting in
a weight-average molecular weight (Mw) in terms of polyethylene
glycol of 1,000,000. The K value was determined to be 95. The
polyvinylpyrrolidone in the aqueous solution will be referred to as
PVP K95.
[0108] Seven types of aqueous polyvinylpyrrolidone solutions as
shown in Table 2 were prepared in the same manner as described
above, except that the amounts of the 10% by mass aqueous sodium
sulfite solution and 10% by mass aqueous t-butylhydroperoxide
solution were changed. The polymer content in the solutions was 20%
by mass. TABLE-US-00002 TABLE 2 Weight-average Polymer molecular
weight K value PVP K30 25,000 30 PVP K60 250,000 60 PVP K70 400,000
70 PVP K80 600,000 80 PVP K90 800,000 90 PVP K110 1,500,000 110 PVP
K140 3,000,000 140
Example 1
I. Preparation of CMP Aqueous Dispersion
[0109] A polyethylene bottle was sequentially charged with the
following components in amounts corresponding to the following
concentration:
[0110] abrasive grains: 0.5% by mass in terms of silica of the
aqueous dispersion containing colloidal silica C25 prepared
above;
[0111] polyvinylpyrrolidone: 0.02% by mass in terms of
polyvinylpyrrolidone of the aqueous solution containing PVP K60
prepared above;
[0112] water-soluble complex-forming agent: 0.3% by mass of
alanine;
[0113] water-insoluble complex-forming agent: 0.5% by mass of
quinaldinic acid;
[0114] surface active agent: 0.1% by mass of potassium
dodecylbenzenesulfonate; and
[0115] oxidant: 2% by mass of ammonium persulfate.
[0116] Potassium hydroxide was added to adjust the pH to
approximately 9. These were stirred for 15 minutes, and ion
exchange water was added to make the total volume 100% by mass. The
mixture was filtered through a 5 .mu.m filter. Consequently, a CMP
aqueous dispersion S1 was obtained. The aqueous dispersion S1 was
measured for viscosity at 25.degree. C. with a B-type viscometer,
resulting in 1.1 mPaa. The pH was 9.1.
II. Evaluation of Polishing Properties
II-1. Polishing Test with Unpatterned Substrates
(1) Evaluation of Removal Rate with Materials
[0117] A porous polyurethane polishing pad
(IC1000-050-(603)-(P)-S400J, manufactured by Nitta Hass
Incorporated) was set to a CMP apparatus (EPO112 manufactured by
Ebara Corporation). The following test substrates were chemically
mechanically polished under the following polishing conditions for
1 minute while supplying the CMP aqueous dispersion S1. The removal
rate was determined as described below.
<Substrates for Testing Removal Rate)
[0118] An 8-inch silicon substrate with a thermally oxidized film
on which a copper film 20,000 .ANG. in thickness was formed
[0119] An 8-inch silicon substrate with a thermally oxidized film
on which a tantrum film 3,000 .ANG. in thickness was formed
[0120] An 8-inch silicon substrate with a thermally oxidized film
on which a titanium film 3,000 .ANG. in thickness was formed
<Polishing Conditions>
[0121] Head rotation: 80 rpm
[0122] Head load: 200 g/cm.sup.2
[0123] Turntable rotation: 100 rpm
[0124] Supply rate of CMP aqueous dispersion: 200 ml/min
<Determination of Removal Rate>
[0125] The resistance of the polished sheet was measured by a DC
four point probe method with a resistivity processor (S-5
manufactured by NPS, INC.), and the thickness of the polished metal
film was calculated from the following formula. The removal rate
was calculated from the thickness reduced by CMP and the polishing
time, and the results were as follows. Metal film thickness
(.ANG.)=sheet resistance (.OMEGA./cm.sup.2)/theoretical resistance
of each metal (.OMEGA./cm).times.10.sup.8 <Removal Rate>
[0126] Removal rate with copper film (R.sub.Cu): 9,600
.ANG./min
[0127] Removal rate with tantrum film (R.sub.Ta): 30 .ANG./min
[0128] Removal rate with titanium film (R.sub.Ti): 80 .ANG./min
[0129] Ratio of removal rate with copper film to removal rate with
tantrum film (R.sub.Cu/R.sub.Ta): 320
[0130] Ratio of removal rate with copper film to removal rate with
titanium film (R.sub.Cu/R.sub.Ti): 120
[0131] The maximum torque current of the turntable of the CMP
apparatus during polishing the copper film was 8.0 A.
(2) Test of Continuous Polishing of Copper
[0132] Substrates having a copper film were consecutively polished
under the same conditions as in the evaluation of removal rate, and
the reduction of removal rate during the consecutive polishing was
studied.
[0133] The removal rate was not lowered while 25 substrates were
consecutively polished.
II-2. Polishing Test with Patterned Substrates
[0134] Patterned wafers (SEMATECH 854 manufactured by SEMATECH
INTERNATIONAL, test substrates having various copper patterns) were
chemically mechanically polished under the same conditions as in
Polishing test with unpatterned substrates, except that the
polishing was performed for 1.3 times longer than the period from
the initiation of the polishing to the termination detected based
on change in turntable torque current. The residual copper on the
fine wiring pattern, and the dishing and corrosion of the copper
wiring were evaluated as follows.
<Residual Copper on Fine Wiring Pattern>
[0135] The patterned wafer had a pattern in which wires 0.18 .mu.m
in width and insulating areas 0.18 .mu.m in width (both 1.6 mm in
length) were alternately contiguous. A precision profiler (HRP-240
manufactured by KLA-Tencor Corporation) measured the thickness of
the copper film remaining on the wires and the insulating areas
over 1.25 mm in a direction perpendicular to the longitudinal
direction. The thickness was measured to be 10 .ANG..
[0136] The residual copper film not more than 100 .ANG. in
thickness may be easily removed by the second CMP with the CMP
aqueous dispersion for removing the barrier metal.
<Dishing in Copper Wiring>
[0137] The patterned wafer had a pattern in which copper wires 100
.mu.m in width and insulating areas 100 .mu.m in width (both 3.0 mm
in length) were alternately contiguous.
[0138] A precision profiler (HRP-240 manufactured by KLA-Tencor
Corporation) measured the depth of dishing in the copper wires over
3.0 mm in a direction perpendicular to the longitudinal direction.
The depth was measured to be 200 .ANG..
<Corrosion>
[0139] A 1 cm square copper area was analyzed with a defect
inspection system (2351 manufactured by KLA-Tencor Corporation),
and corrosions as large as 10 to 100 nm.sup.2 were counted. No
corrosions exceeded 100 nm.sup.2 in size.
Examples 2 to 18 and Comparative Examples 1 to 3
[0140] CMP aqueous dispersions S2 to S18 and R1 to R3 were prepared
in the same manner as in Example 1, except that the types and
amounts of the components for the CMP aqueous dispersions were
changed as shown in Tables 3 and 4. The aqueous dispersions were
adjusted to a pH of approximately 9 by addition of potassium
hydroxide in the same manner as in Example 1. Tables 3 and 4 show
actual pH values measured after addition of potassium hydroxide. In
Table 3, the hyphen (-) indicates that the component was not added.
Examples 8 to 16, 18 and Comparative Examples 2 and 3 used two
types of particles as abrasive grains in combination. Example 17
used two types of water-soluble complex-forming agents in
combination. Example 18 used two types of surface active agents in
combination. Examples 8 to 15, 17, 18 and Comparative Examples 2
and 3 used two types of water-insoluble complex-forming agents in
combination.
[0141] The CMP aqueous dispersions were evaluated in the same
manner as evaluating the CMP aqueous dispersion S1 in Example 1.
The results are shown in Table 5.
[0142] In Examples and Comparative Examples, no corrosions exceeded
100 nm.sup.2 in size.
[0143] The test of continuous polishing of copper in Comparative
Example 1 resulted in approximately 50% reduction of removal rate
when the fifth substrate was polished. TABLE-US-00003 TABLE 3-1 Ex.
1-7 Ex. 8-15 Ex. 16 Ex. 17 Ex. 18 Abrasive grains Type C25 C20 +
C40 C20 + fumed silica C40 C15 + C35 Amount (parts by mass) 0.5 0.4
+ 0.1 0.3 + 0.05 0.5 0.3 + 0.2 Water-soluble Type Alanine Glycine
Glycine Alanine + ammonia Alanine complex Amount (parts by mass)
0.3 0.5 0.3 0.5 + 0.1 0.3 forming agent Water-insoluble Type
Quinaldinic acid Quinaldinic acid + Quinolinic acid Quinaldinic
acid + Quinaldinic acid + complex quinolinic acid quinolinic acid
quinolinic acid forming agent Amount (parts by mass) 0.5 0.3 + 0.2
0.5 0.2 + 0.3 0.3 + 0.2 Surface Type DBS-K DBS-A DBS-K DBS-A DBS-K
+ ACD active agent Amount (parts by mass) 0.1 0.05 0.05 0.1 0.1 +
0.1 Oxidant Type APS APS APS Hydrogen peroxide APS Amount (parts by
mass) 2.0 1.5 1.5 0.2 1.5 PVP Type See Table 4 See Table 4 PVP K95
PVP K95 PVP K95 Amount (parts by mass) See Table 4 See Table 4 0.03
0.03 0.03 Slurry viscosity (mPa s) See Table 4 See Table 4 1.2 1.2
1.2 Slurry pH See Table 4 See Table 4 9.1 9.2 9.0 DBS-K: Potassium
dodecylbenzenesulfoante DBS-A: Ammonium dodecylbenzenesulfonate
ACD: Surfynol 465(trade name, manufactured by Air Products And
Chemicals, Inc., acetylene diol surface active agent) APS: Ammonium
persulfate PVP: Polyvinylpyrrolidone
[0144] TABLE-US-00004 TABLE 3-2 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3
Abrasive grains Type C25 C20 + C40 C20 + C40 Amount (parts by mass)
0.5 0.4 + 0.1 0.4 + 0.1 Water-soluble complex Type Alanine Glycine
Glycine forming agent Amount (parts by mass) 0.3 0.5 0.5
Water-insoluble complex Type Quinaldinic acid Quinaldinic acid +
quinolinic Quinaldinic acid + quinolinic forming agent acid acid
Amount (parts by mass) 0.5 0.3 + 0.2 0.3 + 0.2 Surface active agent
Type DBS-K DBS-A DBS-A Amount (parts by mass) 0.1 0.05 0.05 Oxidant
Type APS APS APS Amount (parts by mass) 2.0 1.5 1.5 PVP Type -- PVP
K30 PVP K80 Amount (parts by mass) -- 1.0 1.0 Slurry viscosity (mPa
s) 1.1 1.1 3.8 Slurry pH 9.1 9.0 9.1 DBS-K: Potassium
dodecylbenzenesulfoante DBS-A: Ammonium dodecylbenzenesulfonate
ACD: Surfynol 465(trade name, manufactured by Air Products And
Chemicals, Inc., acetylene diol surface active agent) APS: Ammonium
persulfate PVP: Polyvinylpyrrolidone
[0145] TABLE-US-00005 TABLE 4 Polyvinylpyrrolidone Amount Slurry
viscosity Type (parts by mass) (mPa s) Slurry pH Ex. 1 PVP K60 0.02
1.1 9.1 Ex. 2 PVP K60 0.1 1.1 9.0 Ex. 3 PVP K60 0.3 1.2 9.1 Ex. 4
PVP K70 0.1 1.1 9.1 Ex. 5 PVP K70 0.3 1.3 9.0 Ex. 6 PVP K80 0.05
1.1 9.2 Ex. 7 PVP K80 0.1 1.2 9.1 Ex. 8 PVP K90 0.05 1.2 9.2 Ex. 9
PVP K90 0.1 1.4 9.0 Ex. 10 PVP K95 0.03 1.2 9.1 Ex. 11 PVP K95 0.05
1.4 9.0 Ex. 12 PVP K110 0.01 1.1 9.1 Ex. 13 PVP K110 0.05 1.6 9.1
Ex. 14 PVP K140 0.2 1.9 9.0 Ex. 15 PVP K140 0.01 1.6 9.2
[0146] TABLE-US-00006 TABLE 5 Test of polishing unpatterned
substrates Continuous polishing Maximum of copper turntable
Reduction of Test of polishing patterned substrates torque current
removal rate Residual copper Dishing Removal rate Removal during
after on in copper (.ANG./min) rate ratio Cu polishing continuous
polishing fine wiring pattern wiring Corrosion Copper Tantrum
Titanium Cu/Ta Cu/Ti (A) of 25 substrates (.ANG.) (.ANG.) (number)
Ex. 1 9600 30 80 320 120 8.0 No 10 200 10 Ex. 2 9500 15 65 633 146
7.8 No 10 190 8 Ex. 3 8500 12 50 708 170 7.5 No 20 170 7 Ex. 4 9100
13 60 700 152 7.7 No 10 180 4 Ex. 5 8400 10 30 840 280 7.5 No 20
160 2 Ex. 6 9000 16 55 563 164 7.6 No 10 170 0 Ex. 7 8800 11 50 800
176 7.5 No 10 150 0 Ex. 8 9200 10 40 920 230 7.4 No 0 130 0 Ex. 9
8300 9 35 922 237 7.5 No 0 100 0 Ex. 10 8800 18 65 489 135 7.4 No 0
150 0 Ex. 11 9000 8 30 1125 300 7.5 No 0 110 0 Ex. 12 8900 20 55
445 162 7.8 No 0 160 2 Ex. 13 8400 7 20 1200 420 7.5 No 20 100 0
Ex. 14 8200 6 15 1367 547 7.5 No 60 80 0 Ex. 15 8000 8 40 1000 200
7.7 No 100 200 2 Ex. 16 10200 15 60 680 170 7.5 No 0 190 3 Ex. 17
8300 18 70 461 119 7.4 No 0 200 4 Ex. 18 8800 20 75 440 117 7.5 No
0 130 0 Comp. Ex. 1 10200 50 130 204 78 10.2 Yes 150 500 30 Comp.
Ex. 2 9800 45 120 218 82 8.0 No 30 400 20 Comp. Ex. 3 4500 5 10 900
450 12.0 No 300 60 0
Example 19
I. Preparation of Kit for Preparing CMP Aqueous Dispersion
I-1. Preparation of Liquid (I)
[0147] A polyethylene bottle was sequentially charged with the
following components in amounts corresponding to the following
concentration:
[0148] abrasive grains: 0.6% by mass in terms of silica of the
aqueous dispersion containing colloidal silica C15 prepared above,
and 0.4% by mass in terms of silica of the aqueous dispersion
containing colloidal silica C35 prepared above;
[0149] polyvinylpyrrolidone: 0.06% by mass in terms of
polyvinylpyrrolidone of the aqueous solution containing PVP K95
prepared above;
[0150] water-soluble complex-forming agent: 0.6% by mass of
alanine;
[0151] water-insoluble complex-forming agents: 0.6% by mass of
quinaldinic acid, and 0.4% by mass of quinolinic acid; and
[0152] surface active agents: 0.2% by mass of potassium
dodecylbenzenesulfonate, and 0.2% by mass of acetylene diol surface
active agent (trade name: SURFYNOL 465 manufactured by Air Products
and Chemicals, Inc.).
[0153] Potassium hydroxide was added to adjust the pH to
approximately 10.5. These were stirred for 15 minutes, and ion
exchange water was added to make the total volume 100% by mass. The
mixture was filtered through a 5 .mu.m filter. Consequently, a
liquid (aqueous dispersion) (I-1) was obtained.
I-2. Preparation of Liquid (II)
[0154] Ammonium persulfate and ion exchange water were mixed
together such that the ammonium persulfate concentration was 3% by
mass. Consequently, a liquid (II-1) was obtained.
II. Preparation of CMP Aqueous Dispersion
[0155] 50 parts by mass of the liquid (I-1) and 50 parts by mass of
the liquid (II-1) were mixed together to give a CMP aqueous
dispersion S19. The CMP aqueous dispersion S19 had a pH of 9.0 and
a viscosity of 1.2 mPaa as measured at 25.degree. C. with a B-type
viscometer. The CMP aqueous dispersion S19 produced by mixing the
separately prepared liquids (I-1) and (II-1) was identical to the
CMP aqueous dispersion S18 produced by simultaneously mixing the
components (see Table 6). TABLE-US-00007 TABLE 6 Ex. 19 Ex. 18
Liquid(I-1) Liquid(II-1) Abrasive grains Type C15 + C35 C15 + C35
Amount (parts by mass) 0.3 + 0.2 0.6 + 0.4 Water-soluble complex
Type Alanine Alanine forming agent Amount (parts by mass) 0.3 0.6
Water-insoluble complex Type Quinaldinic acid + quinolinic
Quinaldinic acid + quinolinic forming agent acid acid Amount (parts
by mass) 0.3 + 0.2 0.6 + 0.4 Surface active agent Type DBS-K + ACD
DBS-K + ACD Amount (parts by mass) 0.1 + 0.1 0.2 + 0.2 Oxidant Type
APS APS Amount (parts by mass) 1.5 3.0 PVP Type PVP K95 PVP K95
Amount (parts by mass) 0.03 0.06 Mixing ratio (by weight) 50 50
Slurry viscosity (mPa s) 1.2 1.2 Slurry pH 9.0 9.0 DBS-K: Potassium
dodecylbenzenesulfonate ACD: Surfynol 465(trade name, manufactured
by Air Products And Chemicals, Inc., acetylene diol surface active
agent) APS: Ammonium persulfate PVP: Polyvinylpyrrolidone
III. Evaluation of Polishing Properties
[0156] The CMP aqueous dispersion S19 was evaluated in the same
manner as evaluating the CMP aqueous dispersion S18 in Example 18.
The results were identical to those of the CMP aqueous dispersion
S18.
Example 20
[0157] The liquids (I-1) and (II-1) prepared in Example 19 were
supplied to a CMP apparatus each at a rate of 100 ml/min, and the
liquids were brought into contact and mixed together on a
turntable. The polishing properties were evaluated in the same
manner as in Example 18. The results were identical to those of the
CMP aqueous dispersion S18.
Example 21
I. Preparation of Kit for Preparing CMP Aqueous Dispersion
I-1. Preparation of Liquid (III)
[0158] A polyethylene bottle was sequentially charged with the
following components in amounts corresponding to the following
concentration:
[0159] abrasive grains: 2.0% by mass in terms of silica of the
aqueous dispersion containing colloidal silica C40 prepared above;
and
[0160] 0.8% by mass in terms of hydrogen peroxide of a 35% by mass
hydrogen peroxide solution.
[0161] Potassium hydroxide was added to adjust the pH to
approximately 9. These were stirred for 15 minutes, and ion
exchange water was added to make the total volume 100% by mass. The
mixture was filtered through a 5 .mu.m filter. Consequently, a
liquid (aqueous dispersion) (III-1) was obtained.
I-2. Preparation of Liquid (IV)
[0162] A polyethylene bottle was sequentially charged with the
following components in amounts corresponding to the following
concentration:
[0163] polyvinylpyrrolidone: 0.12% by mass in terms of
polyvinylpyrrolidone of the aqueous solution containing PVP K95
prepared above;
[0164] water-soluble complex-forming agents: 2.0% by mass of
alanine, and 0.4% by mass of ammonia;
[0165] water-insoluble complex-forming agents: 0.8% by mass of
quinaldinic acid, and 1.2% by mass of quinolinic acid; and
[0166] surface active agent: 0.4% by mass of ammonium
dodecylbenzenesulfonate.
[0167] Potassium hydroxide was added to adjust the pH to
approximately 9. These were stirred for 15 minutes, and ion
exchange water was added to make the total volume 100% by mass. The
mixture was filtered through a 5 .mu.m filter. Consequently, a
liquid (aqueous dispersion) (IV-1) was obtained.
II. Preparation of CMP Aqueous Dispersion
[0168] 25 parts by mass of the liquid (III-1), 25 parts by mass of
the liquid (IV-1) and 50 parts by mass of ion exchange water were
mixed together to give a CMP aqueous dispersion S20. The CMP
aqueous dispersion S20 had a pH of 9.2 and a viscosity of 1.2 mPaa
as measured at 25.degree. C. with a B-type viscometer. The CMP
aqueous dispersion S20 produced by mixing the separately prepared
liquids (III-1) and (IV-1) was identical to the CMP aqueous
dispersion S17 produced by simultaneously mixing the components
(see Table 7). TABLE-US-00008 TABLE 7 Ex. 21 Ion exchange Ex. 17
Liquid(III-1) Liquid(IV-1) water Abrasive grains Type C40 C40
Amount (parts by mass) 0.5 2.0 Water-soluble complex Type Alanine +
ammonia Alanine + ammonia forming agent Amount (parts by mass) 0.5
+ 0.1 2.0 + 0.4 Water-insoluble complex Type Quinaldinic acid +
quinolinic Quinaldinic acid + quinolinic forming agent acid acid
Amount (parts by mass) 0.2 + 0.3 0.8 + 1.2 Surface active agent
Type DBS-A DBS-A Amount (parts by mass) 0.1 0.4 Oxidant Type
Hydrogen peroxide Hydrogen peroxide Amount (parts by mass) 0.2 0.8
PVP Type PVP K95 PVP K95 Amount (parts by mass) 0.03 0.12 Mixing
ratio (by weight) 25 25 50 Slurry viscosity (m Pa s) 1.2 1.2 Slurry
pH 9.2 9.2 DBS-A: Ammonium dodecylbenzenesulfonate PVP:
Polyvinylpyrrolidone
III. Evaluation of Polishing Properties
[0169] The CMP aqueous dispersion S20 was evaluated in the same
manner as evaluating the CMP aqueous dispersion S17 in Example 17.
The results were identical to those of the CMP aqueous dispersion
S17.
Example 22
I. Preparation of Kit for Preparing CMP Aqueous Dispersion
I-1. Preparation of Liquid (V)
[0170] A polyethylene bottle was sequentially charged with the
following components in amounts corresponding to the following
concentration:
[0171] abrasive grains: 1.2% by mass in terms of silica of the
aqueous dispersion containing colloidal silica C15 prepared above,
and 0.8% by mass in terms of silica of the aqueous dispersion
containing colloidal silica C35 prepared above.
[0172] Potassium hydroxide was added to adjust the pH to
approximately 10.5. These were stirred for 15 minutes, and ion
exchange water was added to make the total volume 100% by mass. The
mixture was filtered through a 5 .mu.m filter. Consequently, a
liquid (aqueous dispersion) (V-1) was obtained.
I-2. Preparation of Liquid (VI)
[0173] A polyethylene bottle was sequentially charged with the
following components in amounts corresponding to the following
concentration:
[0174] polyvinylpyrrolidone: 0.12% by mass in terms of
polyvinylpyrrolidone of the aqueous solution containing PVP K95
prepared above;
[0175] water-soluble complex-forming agent: 1.2% by mass of
alanine;
[0176] water-insoluble complex-forming agents: 1.2% by mass of
quinaldinic acid, and 0.8% by mass of quinolinic acid; and
[0177] surface active agents: 0.4% by mass of potassium
dodecylbenzenesulfonate, and 0.4% by mass of acetylene diol surface
active agent (trade name: SURFYNOL 465 manufactured by Air Products
and Chemicals, Inc.).
[0178] Potassium hydroxide was added to adjust the pH to
approximately 10.5. These were stirred for 15 minutes, and ion
exchange water was added to make the total volume 100% by mass. The
mixture was filtered through a 5 .mu.m filter. Consequently, a
liquid (aqueous dispersion) (VI-1) was obtained.
I-3. Preparation of Liquid (VII)
[0179] A liquid containing 3% by mass of ammonium persulfate
(VII-1) was prepared in the same manner as in I-2 of Example
19.
II. Preparation of CMP Aqueous Dispersion
[0180] 25 parts by mass of the liquid (V-1), 25 parts by mass of
the liquid (VI-1) and 50 parts by mass of the liquid (VII-1) were
mixed together to give a CMP aqueous dispersion S21. The CMP
aqueous dispersion S21 had a pH of 9.0 and a viscosity of 1.2 mPaa
as measured at 25.degree. C. with a B-type viscometer. The CMP
aqueous dispersion S21 produced by mixing the separately prepared
liquids (V-1), (VI-1) and (VII-1) was identical to the CMP aqueous
dispersion S18 produced by simultaneously mixing the components
(see Table 8). TABLE-US-00009 TABLE 8 Ex. 22 Ex. 18 Liquid(V-1)
Liquid(VI-1) Liquid(VII-1) Abrasive grains Type C15 + C35 C15 + C35
Amount (parts by mass) 0.3 + 0.2 1.2 + 0.8 Water-soluble complex
Type Alanine Alanine forming agent Amount (parts by mass) 0.3 1.2
Water-insoluble complex Type Quinaldinic acid + Quinaldinic acid +
forming agent quinolinic quinolinic acid acid Amount (parts by
mass) 0.3 + 0.2 1.2 + 0.8 Surface active agent Type DBS-K + ACD
DBS-K + ACD Amount (parts by mass) 0.1 + 0.1 0.4 + 0.4 Oxidant Type
APS APS Amount (parts by mass) 1.5 3.0 PVP Type PVP K95 PVP K95
Amount (parts by mass) 0.03 0.12 Mixing ratio (by weight) 25 25 50
Slurry viscosity (mPa s) 1.2 1.2 Slurry pH 9.0 9.0 DBS-K: Potassium
dodecylbenzenesulfonate ACD: Surfynol 465(trade name, manufactured
by Air Products And Chemicals, Inc., acetylene diol surface active
agent) APS: Ammonium persulfate PVP: Polyvinylpyrrolidone
III. Evaluation of Polishing Properties
[0181] The CMP aqueous dispersion S21 was evaluated in the same
manner as evaluating the CMP aqueous dispersion S18 in Example 18.
The results were identical to those of the CMP aqueous dispersion
S18.
Example 23
[0182] The liquids (V-1), (VI-1) and (VII-1) prepared in Example 22
were supplied to a CMP apparatus at rates of 50 ml/min, 50 ml/min
and 100 ml/min, independently, in place of the CMP aqueous
dispersion S18 in Example 18, and the liquids were brought into
contact and mixed together on a surface plate. The polishing
properties were evaluated in the same manner as in Example 18. The
results were identical to those of the CMP aqueous dispersion
S18.
Example 24
[0183] 50 parts by mass of the liquid (V-1) and 50 parts by mass of
the liquid (VI-1) prepared in Example 22 were mixed together to
give a CMP aqueous dispersion.
[0184] The aqueous dispersion and the liquid (VII-1) prepared in
Example 22 were supplied to a CMP apparatus each at a rate of 100
ml/min in place of the CMP aqueous dispersion S18 in Example 18,
and the aqueous dispersion was brought into contact and mixed with
the liquid on a surface plate. The polishing properties were
evaluated in the same manner as in Example 18. The results were
identical to those of the CMP aqueous dispersion S18.
* * * * *