U.S. patent application number 12/405327 was filed with the patent office on 2009-07-16 for chemical mechanical polishing method.
This patent application is currently assigned to JSR Corporation. Invention is credited to Masayuki Hattori, Hirotaka Shida.
Application Number | 20090181540 12/405327 |
Document ID | / |
Family ID | 36579204 |
Filed Date | 2009-07-16 |
United States Patent
Application |
20090181540 |
Kind Code |
A1 |
Shida; Hirotaka ; et
al. |
July 16, 2009 |
CHEMICAL MECHANICAL POLISHING METHOD
Abstract
A chemical mechanical polishing method, including: chemically
and mechanically polishing a polishing target surface by
continuously performing a first polishing step and a second
polishing step having a polishing rate lower than a polishing rate
of the first polishing step, a chemical mechanical polishing
aqueous dispersion used in the first polishing step and the second
polishing step being a mixture of an aqueous dispersion and an
aqueous solution, and the polishing rate being changed between the
first polishing step and the second polishing step by changing a
mixing ratio of the aqueous dispersion and the aqueous
solution.
Inventors: |
Shida; Hirotaka;
(Yokkaichi-shi, JP) ; Hattori; Masayuki; (Ama-gun,
JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
JSR Corporation
Chuo-ku
JP
|
Family ID: |
36579204 |
Appl. No.: |
12/405327 |
Filed: |
March 17, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11358224 |
Feb 22, 2006 |
|
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|
12405327 |
|
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Current U.S.
Class: |
438/693 ;
257/E21.23 |
Current CPC
Class: |
C09G 1/02 20130101; H01L
21/3212 20130101 |
Class at
Publication: |
438/693 ;
257/E21.23 |
International
Class: |
H01L 21/304 20060101
H01L021/304 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 23, 2005 |
JP |
2005-046374 |
Claims
1. A chemical mechanical polishing method, comprising: chemically
and mechanically polishing a polishing target surface comprising
copper by continuously performing a first polishing step and a
second polishing step having a polishing rate lower than a
polishing rate of the first polishing step, a chemical mechanical
polishing aqueous dispersion used in the first polishing step and
the second polishing step being a mixture of an aqueous dispersion
(I) and an aqueous solution (II), and the polishing rate being
changed between the first polishing step and the second polishing
step by changing a mixing ratio of the aqueous dispersion (I) and
the aqueous solution (II), wherein the polishing rate of the second
step is 10 to 90% of the polishing rate of the first steps wherein:
the aqueous dispersion (I) comprises (A) abrasives, the aqueous
solution (II) comprises at least one selected from the group
consisting of (B) quinolinic acid, (C) a polishing rate improver,
and (D) an oxidizing agent, the pH of the aqueous dispersion (I) is
from 7 to 12 and the pH of the aqueous solution (II) is from 3 to
12.
2. A chemical mechanical polishing method, comprising: chemically
and mechanically polishing a polishing target surface comprising
copper by continuously performing a first polishing step and a
second polishing step having a polishing rate lower than a
polishing rate of the first polishing step, a chemical mechanical
polishing aqueous dispersion used in the first polishing step and
the second polishing step being a mixture of an aqueous dispersion
(I) and an aqueous solution (II), and the polishing rate being
changed between the first polishing step and the second polishing
step by changing a mixing ratio of the aqueous dispersion (I) and
the aqueous solution (II), wherein the first polishing step is
switched to the second polishing step when the thickness of the
polishing target is 200 to 700 nm, wherein: the aqueous dispersion
(I) comprises (A) abrasives, the aqueous solution (II) comprises at
least one selected from the group consisting of (B) quinolinic
acid, (C) a polishing rate improver, and (D) an oxidizing agent,
the pH of the aqueous dispersion (I) is from 7 to 12 and the pH of
the aqueous solution (II) is from 3 to 12.
3. The chemical mechanical polishing method as defined in claim 1,
wherein the aqueous dispersion (I) further comprises (D) an
oxidizing agent.
4. The chemical mechanical polishing method as defined in claim 2,
wherein the aqueous dispersion (I) further comprises (D) an
oxidizing agent.
5. The chemical mechanical polishing method as defined in claim 1,
wherein the aqueous solution (II) further comprises (D) an
oxidizing agent.
6. The chemical mechanical polishing method as defined in claim 2,
wherein the aqueous solution (II) further comprises (D) an
oxidizing agent.
7. The chemical mechanical polishing method as defined in claim 1,
wherein the polishing target surface further comprises an
insulating film and wherein the aqueous solution (II) comprises no
(A) abrasives.
8. The chemical mechanical polishing method as defined in claim 2,
wherein the polishing target surface further comprises an
insulating film and wherein the aqueous solution (II) comprises no
(A) abrasives.
9. The chemical mechanical polishing method as defined in claim 1,
wherein the aqueous dispersion (I) comprises no (C) polishing rate
improver.
10. The chemical mechanical polishing method as defined in claim 2,
wherein the aqueous dispersion (I) comprises no (C) polishing rate
improver.
11. The chemical mechanical polishing method as defined in claim 1,
wherein the pH of the aqueous dispersion (I) is basic.
12. The chemical mechanical polishing method as defined in claim 2,
wherein the pH of the aqueous dispersion (I) is basic.
Description
REFERENCE TO PRIOR APPLICATIONS
[0001] This application is a Continuation application of U.S. Ser.
No. 11/358,224, filed Feb. 22, 2006, now pending; which claims
priority to Japanese Patent Application No. 2005-46374, filed on
Feb. 23, 2005.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a chemical mechanical
polishing method. More particularly, the invention relates to a
chemical mechanical polishing method capable of efficiently
removing an unnecessary wiring material and providing a
high-quality polished surface when manufacturing a semiconductor
device using copper or a copper alloy as the wiring material.
[0003] In recent years, a further increase in the degree of
integration has been demanded for a semiconductor device, and
scaling down of wirings formed in a semiconductor device has
progressed. A damascene method has attracted attention as a
technology capable of achieving further scaling down of wirings of
a semiconductor device. In the damascene method, a desired wiring
is formed by filling a groove formed in an insulating material with
a metal material which forms a wiring and removing an unnecessary
wiring material by chemical mechanical polishing. In the damascene
method, a high polishing rate is required from the viewpoint of an
increase in efficiency and throughput of the polishing step.
[0004] A wiring may be polished excessively when forming a
damascene wiring, whereby the wiring may have a concave shape. Such
a concave wiring shape is called "dishing" or "erosion" and results
in a decrease in the yield of semiconductor devices. A surface
defect called a "scratch" may also occur during polishing and
result in a decrease in the yield of semiconductor devices.
[0005] There may be a case where abrasives remaining on the wiring
or foreign matter remaining on the insulating film causes a problem
after the chemical mechanical polishing step. Or, a phenomenon
called "corrosion" in which the wiring is corroded may also occur.
This also significantly affects the yield of semiconductor
devices.
[0006] Various chemical mechanical polishing aqueous dispersions
have been proposed in order to reduce occurrence of dishing or
erosion to improve the planarity of the polished surface or to
reduce occurrence of a scratch or corrosion.
[0007] For example, JP-A-10-163141 discloses that a composition
containing abrasives, water, and an iron compound has an effect of
reducing occurrence of dishing. JP-A-2000-160141 discloses that a
composition containing abrasives, .alpha.-alanine, hydrogen
peroxide, and water is effective for reducing occurrence of dishing
and erosion to provide a polished surface exhibiting excellent
planarity. JP-A-10-44047 discloses that the planarity of the
polished surface is improved by adding a surfactant to a chemical
mechanical polishing aqueous dispersion.
[0008] In the chemical mechanical polishing step, a high polishing
rate is required in addition to improving the planarity of the
polished surface and reducing occurrence of surface defects.
However, few studies have been conducted on a chemical mechanical
polishing aqueous dispersion which can achieve these requirements
in combination.
SUMMARY
[0009] The invention may provide a chemical mechanical polishing
method capable of providing a high-quality polished surface which
exhibits excellent planarity and in which occurrence of surface
defects is reduced, and achieving a high polishing rate.
[0010] The above problems can be solved by the chemical mechanical
polishing method according to one aspect of the invention.
[0011] According to one aspect of the invention, there is provided
a chemical mechanical polishing method, comprising:
[0012] chemically and mechanically polishing a polishing target
surface by continuously performing a first polishing step and a
second polishing step having a polishing rate lower than a
polishing rate of the first polishing step, a chemical mechanical
polishing aqueous dispersion used in the first polishing step and
the second polishing step being a mixture of an aqueous dispersion
(I) and an aqueous solution (II), and the polishing rate being
changed between the first polishing step and the second polishing
step by changing a mixing ratio of the aqueous dispersion (I) and
the aqueous solution (II).
[0013] In this chemical mechanical polishing method,
[0014] the aqueous dispersion (I) may include (A) abrasives and (B)
quinolinic acid;
[0015] the aqueous solution (II) may include (C) a polishing rate
improver; and
[0016] when amounts of the aqueous dispersion (I) and the aqueous
solution (II) supplied in the first polishing step are respectively
denoted by S(I-1) and S(II-1) and amounts of the aqueous dispersion
(I) and the aqueous solution (II) supplied in the second polishing
step are respectively denoted by S(I-2) and S(II-2),
"S(I-1)/S(II-1)<S(I-2)/S(II-2)" may be satisfied.
[0017] In this chemical mechanical polishing method, the aqueous
dispersion (I) may further include (D) an oxidizing agent.
[0018] In this chemical mechanical polishing method,
[0019] the aqueous solution (II) may further include (D) an
oxidizing agent.
[0020] In this chemical mechanical polishing method,
[0021] the aqueous dispersion (I) may include (A) abrasives and (D)
an oxidizing agent;
[0022] the aqueous solution (II) may include (B) quinolinic acid;
and
[0023] when amounts of the aqueous dispersion (I) and the aqueous
solution (II) supplied in the first polishing step are respectively
denoted by S(I-1) and S(II-1) and amounts of the aqueous dispersion
(I) and the aqueous solution (II) supplied in the second polishing
step are respectively denoted by S(I-2) and S(II-2),
"S(I-1)/S(II-1)<S(I-2)/S(II-2)" may be satisfied.
[0024] In this chemical mechanical polishing method, the aqueous
dispersion (I) may include (A) abrasives and (B') a compound having
a heterocyclic ring (excluding quinolinic acid);
[0025] the aqueous solution (II) may include (C) a polishing rate
improver and (D) an oxidizing agent; and
[0026] when amounts of the aqueous dispersion (I) and the aqueous
solution (II) supplied in the first polishing step are respectively
denoted by S(I-1) and S(II-1) and amounts of the aqueous dispersion
(I) and the aqueous solution (II) supplied in the second polishing
step are respectively denoted by S(I-2) and S(II-2),
"S(I-1)/S(II-1)<S(I-2)/S(II-2)" may be satisfied.
[0027] In this chemical mechanical polishing method,
[0028] the aqueous dispersion (I) may include (A) abrasives, (B') a
compound having a heterocyclic ring (excluding quinolinic acid),
and (D) an oxidizing agent;
[0029] the aqueous solution (II) may include (C) a polishing rate
improver; and
[0030] when amounts of the aqueous dispersion (I) and the aqueous
solution (II) supplied in the first polishing step are respectively
denoted by S(I-1) and S(II-1) and amounts of the aqueous dispersion
(I) and the aqueous solution (II) supplied in the second polishing
step are respectively denoted by S(I-2) and S(II-2),
"S(I-1)/S(II-1)<S(I-2)/S(II-2)" may be satisfied.
[0031] According to this chemical mechanical polishing method, a
high-quality polished surface which exhibits excellent planarity
and in which occurrence of surface defects is reduced can be
obtained, and a high polishing rate can be achieved.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0032] FIGS. 1A to 1C are cross-sectional views schematically
showing a chemical mechanical polishing method according to one
embodiment of the invention.
[0033] FIGS. 2A to 2C are cross-sectional views schematically
showing a chemical mechanical polishing method according to one
embodiment of the invention.
DETAILED DESCRIPTION OF THE EMBODIMENT
1. Chemical Mechanical Polishing Method
[0034] According to one embodiment of the invention, there is
provided a chemical mechanical polishing method, comprising
chemically and mechanically polishing a polishing target surface by
continuously performing a first polishing step and a second
polishing step having a polishing rate lower than a polishing rate
of the first polishing step, a chemical mechanical polishing
aqueous dispersion used in the first polishing step and the second
polishing step being a mixture of an aqueous dispersion (I) and an
aqueous solution (II), and the polishing rate being changed between
the first polishing step and the second polishing step by changing
a mixing ratio of the aqueous dispersion (I) and the aqueous
solution (II).
[0035] The chemical mechanical polishing method according to one
embodiment of the invention fully exerts its advantageous effects
when removing an unnecessary metal wiring material in a step of
manufacturing a semiconductor device by the damascene method. As an
example of the polishing target of the chemical mechanical
polishing method according to one embodiment of the invention, a
composite substrate material 1 having a structure as shown in FIG.
1A can be given. The composite substrate material 1 includes a
substrate 11 formed of silicon or the like, an insulating film 12
which is stacked on the surface of the substrate 11 and in which a
depression for wiring such as a groove is formed, a barrier metal
film 13 provided to cover the surface of the insulating film 12 and
the bottom and the inner wall of the depression for wiring, and a
metal film 14 formed of a wiring material provided in the
depression for wiring and formed on the barrier metal film 13.
[0036] As shown in FIG. 2A, the polishing target of the chemical
mechanical polishing method according to one embodiment of the
invention may include an insulating film 21 provided between the
substrate 11 and the insulating film 12 and formed of silicon oxide
or the like, and an insulating film 22 formed of silicon nitride or
the like on the insulating film 21.
[0037] As examples of the metal used as the wiring material,
tungsten, aluminum, copper, and an alloy containing such a metal
can be given. The chemical mechanical polishing method according to
one embodiment of the invention fully exerts its effects when using
copper or a copper alloy as the wiring material. The copper content
in the copper alloy is preferably 95 wt % or more.
[0038] As examples of the barrier metal, tantalum, tantalum
nitride, titanium, titanium nitride, an tantalum-niobium alloy, and
the like can be given.
[0039] As examples of the insulating film, a silicon oxide film
formed by a vacuum process (e.g. plasma enhanced TEOS (PETEOS)
film, high density plasma enhanced TEOS (HDP) film, or silicon
oxide film formed by chemical vapor deposition), a fluorine-doped
silicate glass (FSG) insulating film, a boron phosphorus silicate
glass (BPSG) film, a silicon oxynitride (SiON) insulating film, a
silicon nitride film, a low-dielectric-constant insulating film,
and the like can be given.
[0040] The chemical mechanical polishing method according to one
embodiment of the invention fully exerts its effects when using the
chemical mechanical polishing method for chemically and
mechanically polishing the metal material of the metal film 14 in
an area other than the metal wiring provided in the depression for
wiring until a predetermined surface (e.g. barrier metal film 13)
is exposed (see FIGS. 1B and 2B).
[0041] The barrier metal film 13 is then chemically and
mechanically polished by a known method so that the barrier metal
film formed in the area other than the bottom and the inner wall of
the depression for wiring is completely removed, whereby an
accurately planarized damascene wiring is formed (see FIGS. 1C and
2C).
[0042] In the chemical mechanical polishing method according to one
embodiment of the invention, the first polishing step having a high
polishing rate and the second polishing step having a polishing
rate lower than that of the first polishing step are continuously
performed when removing an unnecessary metal wiring material. The
first step is switched to the second step when the residual
thickness of an unnecessary wiring material is reduced to
preferably 0 to 700 nm, and still more preferably to 200 to 500
nm.
[0043] A highly planarized high quality polished surface can be
obtained efficiently (in a short polishing time) by switching from
the first polishing step to the second polishing step at such a
timing.
[0044] The removal rate of an unnecessary metal wiring material in
the second polishing step is preferably 90% or less, more
preferably 10 to 80%, and still more preferably 20 to 70% of the
removal rate in the first polishing step.
[0045] The chemical mechanical polishing aqueous dispersion used in
the chemical mechanical polishing method according to one
embodiment of the invention is a mixture of the aqueous dispersion
(I) and the aqueous solution (II). The polishing rate can be
changed between the first polishing step and the second polishing
step by changing the mixing ratio of the aqueous dispersion (I) and
the aqueous solution (II).
[0046] The mixing ratio of the aqueous dispersion (I) and the
aqueous solution (II) in the first polishing step and the mixing
ratio of the aqueous dispersion (I) and the aqueous solution (II)
in the second polishing step differ depending on the aqueous
dispersion (I) and the aqueous solution (II) used. For example, the
following modes (i) to (iv) may be employed. Note that one
embodiment of the invention is not limited to the following modes,
which merely illustrate examples of the modes of one embodiment of
the invention.
[0047] (i) A chemical mechanical polishing method in which the
aqueous dispersion (I) includes (A) abrasives and (B) quinolinic
acid, the aqueous solution (II) includes (C) a polishing rate
improver, and, when the amounts of the aqueous dispersion (I) and
the aqueous solution (II) supplied in the first polishing step are
respectively denoted by S(I-1) and S(II-1) and the amounts of the
aqueous dispersion (I) and the aqueous solution (II) supplied in
the second polishing step are respectively denoted by S(I-2) and
S(II-2), "S(I-1)/S(II-1)<S(I-2)/S(II-2)" is satisfied.
[0048] (ii) A chemical mechanical polishing method in which the
aqueous dispersion (I) includes (A) abrasives and (D) an oxidizing
agent, the aqueous solution (II) includes (B) quinolinic acid, and,
when the amounts of the aqueous dispersion (I) and the aqueous
solution (II) supplied in the first polishing step are respectively
denoted by S(I-1) and S(II-1) and the amounts of the aqueous
dispersion (I) and the aqueous solution (II) supplied in the second
polishing step are respectively denoted by S(I-2) and S(II-2),
"S(I-1)/S(II-1)<S(I-2)/S(II-2)" is satisfied.
[0049] (iii) A chemical mechanical polishing method in which the
aqueous dispersion (I) includes (A) abrasives and (B') a compound
having a heterocyclic ring (excluding quinolinic acid), the aqueous
solution (II) includes (C) a polishing rate improver and (D) an
oxidizing agent, and, when the amounts of the aqueous dispersion
(I) and the aqueous solution (II) supplied in the first polishing
step are respectively denoted by S(I-1) and S(II-1) and the amounts
of the aqueous dispersion (I) and the aqueous solution (II)
supplied in the second polishing step are respectively denoted by
S(I-2) and S(II-2), "S(I-1)/S(II-1)<S(I-2)/S(II-2)" is
satisfied.
[0050] (iv) A chemical mechanical polishing method in which the
aqueous dispersion (I) includes (A) abrasives, (B') a compound
having a heterocyclic ring (excluding quinolinic acid), and (D) an
oxidizing agent, the aqueous solution (II) includes (C) a polishing
rate improver, and, when the amounts of the aqueous dispersion (I)
and the aqueous solution (II) supplied in the first polishing step
are respectively denoted by S(I-1) and S(II-1) and the amounts of
the aqueous dispersion (I) and the aqueous solution (II) supplied
in the second polishing step are respectively denoted by S(I-2) and
S(II-2), "S(I-1)/S(II-1)<S(I-2)/S(II-2)" is satisfied.
[0051] As the abrasives (A) which may be included in the aqueous
dispersion (I) in the methods (i) to (iv), at least one type of
abrasives selected from the group consisting of inorganic
particles, organic particles, and organic-inorganic composite
particles can be given.
[0052] As examples of the inorganic particles, silica, alumina,
titania, zirconia, ceria, and the like can be given. As examples of
the silica, fumed silica, silica synthesized by a sol-gel method,
colloidal silica, and the like can be given. The fumed silica may
be obtained by reacting silicon chloride or the like with oxygen
and water in a gaseous phase. The silica synthesized by the sol-gel
method may be obtained by hydrolysis and/or condensation of an
alkoxysilicon compound as the raw material. The colloidal silica
may be obtained by an inorganic colloid method using a raw material
purified in advance, for example.
[0053] As examples of the organic particles, polyvinyl chloride,
styrene (co)polymer, polyacetal, polyester, polyamide,
polycarbonate, olefin (co)polymer, phenoxy resin, acrylic
(co)polymer, and the like can be given. As examples of the olefin
(co)polymer, polyethylene, polypropylene, poly-1-butene,
poly-4-methyl-1-pentene, and the like can be given. As examples of
the acrylic (co)polymer, polymethyl methacrylate and the like can
be given.
[0054] The type and the configuration of the organic-inorganic
composite particles are not particularly limited insofar as
inorganic particles and organic particles as mentioned above are
integrally formed in such a manner that the inorganic particles and
the organic particles are not easily separated during the chemical
mechanical polishing step.
[0055] The organic-inorganic composite particles may have one of
the following configurations (i) to (iii).
[0056] (i) Organic-inorganic composite particles obtained by
polycondensation of an alkoxide compound of a metal or silicon in
the presence of organic particles. As examples of the alkoxide
compound of a metal or silicon, an alkoxysilane, aluminum alkoxide,
titanium alkoxide, and the like can be given. The resulting
polycondensate may be bonded to a functional group of the organic
particle either directly or through an appropriate coupling agent
(e.g. silane coupling agent).
[0057] (ii) Organic-inorganic composite particles in which organic
particles and inorganic particles having zeta potentials of
opposite polarities (positive or negative) are bonded through an
electrostatic force. In this case, the composite particles may be
formed by mixing the organic particles and the inorganic particles
in a pH region in which the organic particles and the inorganic
particles have zeta potentials of opposite polarities, or may be
formed by mixing the organic particles and the inorganic particles
in a pH region in which the organic particles and the inorganic
particles have zeta potentials of an identical polarity and
changing the solution properties to a pH region in which the
organic particles and the inorganic particles have zeta potentials
of opposite polarities.
[0058] (iii) Organic-inorganic composite particles obtained by
polycondensation of an alkoxide compound of a metal or silicon in
the presence of the composite particles (ii). As the alkoxide
compound of a metal or silicon, the alkoxide compound given for the
organic-inorganic composite particles (i) may be used.
[0059] As the abrasives (A) included in the chemical mechanical
polishing aqueous dispersion according to one embodiment of the
invention, silica or the organic-inorganic composite particle is
preferable.
[0060] The impurity metal content in the abrasives (A) is
preferably 10 ppm or less, more preferably 5 ppm or less, still
more preferably 3 ppm or less, and particularly preferably 1 ppm or
less. As examples of the impurity metal, iron, nickel, zinc, and
the like can be given.
[0061] The average particle diameter of the abrasives (A) is
preferably 5 to 1,000 nm, more preferably 7 to 700 nm, and still
more preferably 10 to 500 nm. An excellent polished surface can be
obtained at an appropriate polishing rate by using the abrasives
having an average particle diameter in this range.
[0062] The compound (B') having a heterocyclic ring which may be
included in the aqueous dispersion (I) in the methods (iii) and
(iv) is preferably an organic compound having at least one
heterocyclic ring selected from the group consisting of
heterocyclic five-membered rings and heterocyclic six-membered
rings containing at least one nitrogen atom. As examples of the
heterocyclic ring, heterocyclic five-membered rings such as a
pyrrole structure, an imidazole structure, and a triazole
structure, and heterocyclic six-membered rings such as a pyridine
structure, a pyrimidine structure, a pyridazine structure, and a
pyrazine structure can be given. The heterocyclic rings may form a
condensed ring. Specific examples of such a condensed ring include
an indole structure, isoindole structure, benzimidazole structure,
benzotriaole structure, quinoline structure, isoquinoline
structure, quinazoline structure, cinnoline structure, phthalazine
structure, quinoxaline structure, acridine structure, and the
like.
[0063] It is preferable to use an organic compound having a
pyridine structure, quinoline structure, benzimidazole structure,
or benzotriaole structure. As such an organic compound, quinaldic
acid, benzimidazole, and benzotriazole are preferable, with
quinaldic acid being still more preferable.
[0064] Note that quinolinic acid is excluded from the compound (B')
having a heterocyclic ring.
[0065] As the polishing rate improver (C) which may be included in
the aqueous solution (II) in the methods (i), (iii), and (iv), at
least one polishing rate improver selected from the group
consisting of an amino acid, aminopolycarboxylic acid, amine
compound, amino alcohol, phosphonic acid, halide ion, thiosulphate
ion, and ammonium ion can be given.
[0066] As examples of the amino acid, glycine, alanine, glutamic
acid, and the like can be given.
[0067] As examples of the aminopolycarboxylic acid,
ethylenediaminetetraacetic acid and the like can be given.
[0068] As examples of the amine compound, ethylenediamine,
diethylamine, triethylamine, and the like can be given.
[0069] As examples of the amino alcohol, triethanolamine and the
like can be given. In particular, it is preferable to use the
ammonium ion, amino acid, amine compound, or aminopolycarboxylic
acid.
[0070] As examples of the oxidizing agent (D) which may be included
in the aqueous dispersion (I) in the methods (ii) and (iv) and the
aqueous solution (II) in the method (iii), hydrogen peroxide,
organic peroxide, permanganic acid compound, bichromic acid
compound, halogen acid compound, nitric acid compound, perhalogen
acid compound, persulfate, heteropolyacid, and the like can be
given.
[0071] As examples of the organic peroxide, peracetic acid,
perbenzoic acid, tert-butyl hydroperoxide, and the like can be
given.
[0072] As examples of the permanganic acid compound, potassium
permanganate and the like can be given.
[0073] As examples of the bichromic acid compound, potassium
bichromate and the like can be given.
[0074] As examples of the halogen acid compound, potassium iodate
and the like can be given.
[0075] As examples of the nitric acid compound, nitric acid, iron
nitrate, and the like can be given.
[0076] As examples of the perhalogen acid compound, perchloric acid
and the like can be given.
[0077] As examples of the persulfate, ammonium persulfate and the
like can be given.
[0078] As examples of the heteropolyacid, silicomolybdic acid,
silicotungstic acid, and the like can be given.
[0079] It is preferable to use hydrogen peroxide, organic peroxide,
or persulfate since the decomposition product is harmless.
[0080] In the method (i), at least one of the aqueous dispersion
(I) and the aqueous solution (II) may include the oxidizing agent
(D).
[0081] The aqueous dispersion (I) in the methods (i) and (ii) may
arbitrarily include the compound (B') having a heterocyclic ring
which may be included in the aqueous dispersion (I) in the methods
(iii) and (iv) in addition to the above-mentioned components.
[0082] In the methods (i) to (iv), the aqueous dispersion (I) and
the aqueous solution (II) may include an acid, base, surfactant,
water-soluble polymer, or the like in addition to the
above-mentioned components.
[0083] As examples of the acid, an organic acid and an inorganic
acid can be given.
[0084] As examples of the organic acid, p-toluenesulfonic acid,
dodecylbenzenesulfonic acid, isoprenesulfonic acid, gluconic acid,
lactic acid, citric acid, tartaric acid, malic acid, glycolic acid,
malonic acid, formic acid, oxalic acid, succinic acid, fumaric
acid, maleic acid, phthalic acid, and the like can be given.
[0085] As examples of the inorganic acid, nitric acid, sulfuric
acid, phosphoric acid, and the like can be given.
[0086] As examples of the base, an organic base and an inorganic
base can be given. As examples of the organic base, tetramethyl
hydroxide and the like can be given. As examples of the inorganic
base, an alkali metal hydroxide can be given. As specific examples
of the alkali metal hydroxide, sodium hydroxide, potassium
hydroxide, rubidium hydroxide, cesium hydroxide, and the like can
be given.
[0087] The acid and the base may also be used to adjust the pH of
the aqueous dispersion (I) and the aqueous solution (II).
[0088] As examples of the surfactant, a cationic surfactant, an
anionic surfactant, and a nonionic surfactant can be given.
[0089] As examples of the cationic surfactant, an aliphatic amine
salt, aliphatic ammonium salt, and the like can be given.
[0090] As examples of the anionic surfactant, a carboxylate,
sulfonate, sulfate salt, phosphate salt, and the like can be given.
As examples of the carboxylate, fatty acid soap, alkyl ether
carboxylate, and the like can be given.
[0091] As examples of the sulfonate, alkylbenzenesulfonate,
alkylnaphthalenesulfonate, .alpha.-olefin sulfonate, and the like
can be given.
[0092] As examples of the sulfate salt, higher alcohol sulfate,
alkyl ether sulfate, and the like can be given.
[0093] As examples of the phosphate, alkyl phosphate and the like
can be given.
[0094] As examples of the nonionic surfactant, an ether type
surfactant, an ether ester type surfactant, an ester type
surfactant, an acetylene type surfactant, and the like can be
given.
[0095] As examples of the ether type surfactant, a polyoxyethylene
alkyl ether and the like can be given.
[0096] As examples of the ether ester type surfactant, a
polyoxyethylene ether of an glycerol ester and the like can be
given.
[0097] As examples of the ester type surfactant, a polyethylene
glycol fatty acid ester, glycerol ester, sorbitan ester, and the
like can be given.
[0098] As examples of the acetylene type surfactant, an acetylene
alcohol, acetylene glycol, ethylene oxide addition product of
acetylene diol, and the like can be given.
[0099] As examples of the water-soluble polymer, polyacrylamide,
polyacrylic acid, polyvinyl alcohol, polyvinylpyrrolidone,
hydroxyethylcellulose, and the like can be given.
[0100] The amount of the abrasives (A) used in the aqueous
dispersion (I) in the methods (i) to (iv) is preferably 0.01 to 10
wt %, more preferably 0.02 to 8 wt %, and still more preferably 0.1
to 5 wt % of the total amount of the aqueous dispersion.
[0101] The amount of the quinolinic acid (B) used in the aqueous
dispersion (I) in the method (i) is preferably 0.01 to 10 wt %,
more preferably 0.02 to 5 wt %, and still more preferably 0.1 to 2
wt % of the total amount of the aqueous dispersion.
[0102] The amount of the quinolinic acid used in the aqueous
solution (II) in the method (ii) is preferably 0.01 to 5 wt %, more
preferably 0.02 to 4 wt %, and still more preferably 0.05 to 3 wt %
of the total amount of the aqueous solution.
[0103] The amount of the compound (B') having a heterocyclic ring
used in the aqueous dispersion (I) in the methods (iii) and (iv) is
preferably 0.01 to 10 wt %, more preferably 0.02 to 5 wt %, and
still more preferably 0.1 to 2 wt % of the total amount of the
aqueous dispersion.
[0104] When the aqueous dispersion (I) in the methods (i) and (ii)
includes the compound (B') having a heterocyclic ring, the amount
of the compound (B') is preferably 0.01 to 10 wt %, more preferably
0.02 to 5 wt %, and still more preferably 0.1 to 2 wt % of the
total amount of the aqueous dispersion.
[0105] The amount of the polishing rate improver (C) used in the
aqueous solution (II) in the methods (i), (iii), and (iv) is
preferably 0.01 to 5 wt %, more preferably 0.02 to 4 wt %, and
still more preferably 0.05 to 3 wt % of the total amount of the
aqueous solution.
[0106] The amount of the oxidizing agent (D) used in the aqueous
dispersion (I) in the methods (ii) and (iv) is preferably 0.01 to 5
wt %, more preferably 0.02 to 4 wt %, and still more preferably
0.05 to 1 wt % of the total amount of the aqueous dispersion.
[0107] The amount of the oxidizing agent (D) used in the aqueous
solution (II) in the method (iii) is preferably 0.01 to 10 wt %,
more preferably 0.02 to 8 wt %, and still more preferably 0.05 to 5
wt % of the total amount of the aqueous solution.
[0108] When the aqueous dispersion (I) in the method (i) includes
the oxidizing agent (D), the amount of the oxidizing agent (D) is
preferably 0.01 to 5 wt %, more preferably 0.02 to 4 wt %, and
still more preferably 0.05 to 1 wt % of the total amount of the
aqueous dispersion.
[0109] When the aqueous solution (II) in the method (i) includes
the oxidizing agent (D), the amount of the oxidizing agent (D) is
preferably 0.01 to 10 wt %, more preferably 0.02 to 8 wt %, and
still more preferably 0.05 to 5 wt % of the total amount of the
aqueous solution.
[0110] When using ammonium persulfate as the oxidizing agent (D),
ammonium persulfate functions as the oxidizing agent (D), and
ammonium ions produced due to electrolytic dissociation of ammonium
persulfate in the aqueous dispersion or the aqueous solution
function as the polishing rate improver (C). Therefore, the amount
of ammonium persulfate corresponding to the ammonium ions should be
calculated as the amount of the polishing rate improver (C).
[0111] When the aqueous dispersion (I) in the methods (i) to (iv)
includes the surfactant, the amount of the surfactant is preferably
0.5 wt % or less, and still more preferably 0.01 to 5 wt % of the
total amount of the aqueous dispersion.
[0112] The pH of the aqueous dispersion (I) in the methods (i) to
(iv) is preferably 7 to 12.
[0113] The pH of the aqueous solution (II) in the methods (i) to
(iv) is preferably 3 to 12.
[0114] In the chemical mechanical polishing method according to one
embodiment of the invention, when the amounts of the aqueous
dispersion (I) and the aqueous solution (II) supplied in the first
polishing step are respectively denoted by S(I-1) and S(II-1) and
the amounts of the aqueous dispersion (I) and the aqueous solution
(II) supplied in the second polishing step are respectively denoted
by S(I-2) and S(II-2), "S(I-1)/S(II-1)<S(I-2)/S(II-2)" is
satisfied. The value "S(I-1)/S(II-1)" in the methods (i) to (iv) is
preferably 0.01 to 5, and still more preferably 0.05 to 3. The
value "S(I-2)/S(II-2)" in the methods (i) to (iv) is preferably
0.05 or more, and still more preferably 0.2 or more. The second
polishing step may be performed using only the aqueous dispersion
(I) without supplying the aqueous solution (II).
[0115] It suffices that the chemical mechanical polishing aqueous
dispersion used in one embodiment of the invention be provided so
that the aqueous dispersion (I) and the aqueous solution (II) are
separately provided and are integrally mixed during polishing. The
mixing method and the mixing time are not particularly limited.
[0116] For example, the aqueous dispersion (I) and the aqueous
solution (II) may be separately supplied to a polishing system and
mixed on a platen. Or, the aqueous dispersion (I) and the aqueous
solution (II) may be mixed before entering the polishing system or
in the polishing system when supplied through a line, or may be
mixed in a mixing tank additionally provided. A line mixer or the
like may be used to more uniformly mix the aqueous dispersion (I)
and the aqueous solution (II).
[0117] The chemical mechanical polishing method according to one
embodiment of the invention may be carried out by a known method
using a commercially available chemical mechanical polishing system
and a commercially available chemical mechanical polishing pad.
[0118] For example, when using a chemical mechanical polishing
system "EPO112" manufactured by Ebara Corporation, the method
according to one embodiment of the invention may be carried out
under the following conditions.
[0119] Supply rate of chemical mechanical polishing aqueous
dispersion (total amount of aqueous dispersion (I) and aqueous
solution (II)): preferably 100 to 400 mL/min, and still more
preferably 150 to 350 mL/min
[0120] Platen rotational speed: preferably 30 to 150 rpm, and still
more preferably 50 to 130 rpm
[0121] Polishing head rotational speed: preferably 20 to 150 rpm,
and still more preferably 30 to 130 rpm
[0122] Polishing head pressure: preferably 0.1 to 5 psi, and still
more preferably 0.5 to 4 psi
[0123] The above-described chemical mechanical polishing method
according to one embodiment of the invention is capable of
providing a high-quality polished surface which exhibits excellent
planarity and in which occurrence of surface defects is reduced,
and achieves a high polishing rate.
2. EXAMPLE
[0124] The chemical mechanical polishing method according to the
invention is described below in more detail by way of examples.
Note that the chemical mechanical polishing method according to the
invention is not limited to the following examples.
2.1. Preparation of Aqueous Dispersion Containing Abrasives
2.1.1. Preparation of Aqueous Dispersion Containing Fumed Silica
Particles
[0125] 2 kg of fumed silica particles ("Aerosil #90" manufactured
by Nippon Aerosil Co., Ltd.) were dispersed in 6.7 kg of
ion-exchanged water using an ultrasonic mixer, and filtered through
a filter having a pore diameter of 5 .mu.m to prepare an aqueous
dispersion containing 10 wt % of fumed silica having an average
particle diameter of 220 nm.
2.1.2. Preparation of Aqueous Dispersion Containing Colloidal
Silica
[0126] A 2 L flask was charged with 70 g of 25 wt % aqueous
ammonia, 40 g of ion-exchanged water, 175 g of ethanol, and 21 g of
tetraethoxysilane. The mixture was heated to 60.degree. C. with
stirring at 180 rpm. The mixture was stirred at 60.degree. C. for
two hours and then cooled to obtain a colloidal silica/alcohol
dispersion having an average particle diameter of 97 nm. An
operation of removing the alcohol from the dispersion at 80.degree.
C. using an evaporator while adding ion-exchanged water to the
dispersion was performed several times to remove the alcohol from
the dispersion to prepare an aqueous dispersion containing 10 wt %
of colloidal silica having an average particle diameter of 97
nm.
2.1.3. Preparation of Aqueous Dispersion Containing
Organic-Inorganic Composite particles
2.1.3-1. Preparation of Aqueous Dispersion Containing Organic
Particles
[0127] A 2 L flask was charged with 90 parts by weight of methyl
methacrylate, 5 parts by weight of methoxy polyethylene glycol
methacrylate ("NK Ester M-90G #400" manufactured by Shin-Nakamura
Chemical Co., Ltd.), 5 parts by weight of 4-vinylpyridine, 2 parts
by weight of an azo initiator ("V50" manufactured by Wako Pure
Chemical Industries, Ltd.), and 400 parts by weight of
ion-exchanged water. The mixture was heated to 70.degree. C. with
stirring in a nitrogen gas atmosphere and polymerized for six
hours. As a result, an aqueous dispersion containing polymethyl
methacrylate particles having a functional group containing a
cation of an amino group and a polyethylene glycol chain and having
an average particle diameter of 150 nm was obtained. The
polymerization yield was 95%.
2.1.3-2. Preparation of Aqueous Dispersion Containing Composite
Particles
[0128] A 2 L flask was charged with 100 parts by weight of the
aqueous dispersion containing 10 wt % of the polymethyl
methacrylate particles obtained in 2.1.3-1. After the addition of 1
part by weight of methyltrimethoxysilane, the mixture was stirred
at 40.degree. C. for two hours. The pH of the mixture was adjusted
to 2.0 using nitric acid to obtain an aqueous dispersion (a). The
zeta potential of the polymethyl methacrylate particles contained
in the aqueous dispersion (a) was +17 mV.
[0129] The pH of an aqueous dispersion containing 10 wt % of
colloidal silica ("Snowtex O" manufactured by Nissan Chemical
Industries, Ltd.) was adjusted to 8.0 using potassium hydroxide to
obtain an aqueous dispersion (b). The zeta potential of the silica
particles contained in the aqueous dispersion (b) was -40 mV.
[0130] 50 parts by weight of the aqueous dispersion (b) was slowly
added to and mixed with 100 parts by weight of the aqueous
dispersion (a) in two hours. The mixture was then stirred four two
hours to obtain an aqueous dispersion containing particles in which
the silica particles adhered to the polymethyl methacrylate
particles. After the addition of 2 parts by weight of
vinyltriethoxysilane to the aqueous dispersion, the mixture was
stirred for one hour. After the addition of 1 part by weight of
tetraethoxysilane, the mixture was heated to 60.degree. C. The
mixture was stirred for three hours and then cooled to obtain an
aqueous dispersion containing organic-inorganic composite
particles. The average particle diameter of the organic-inorganic
composite particles was 180 nm. The silica particles adhered to 80%
of the surface of the polymethyl methacrylate particle.
2.2. Example 1
2.2.1. Preparation of Aqueous Dispersion (I)
[0131] A polyethylene container was charged with the aqueous
dispersion containing fumed silica particles prepared in 2.1.1. in
such an amount that the amount of fumed silica was 2 wt % of the
total amount of the chemical mechanical polishing aqueous
dispersion.
[0132] After the addition of 0.5 wt % of quinaldic acid, the
mixture was sufficiently stirred. After the addition of 0.1 wt % of
potassium dodecylbenzenesulfonate and ammonium hydroxide as a pH
adjusting agent with stirring, the mixture was diluted with
ion-exchanged water to obtain a chemical mechanical polishing
aqueous dispersion (I) having a pH of 10.0.
2.2.2. Preparation of Aqueous Solution (II)
[0133] A polyethylene container was charged with quinolinic acid in
an amount of 0.5 wt % of the total amount of the aqueous solution.
After the addition of potassium hydroxide (solid) as a pH adjusting
agent, a predetermined amount of ion-exchanged water was added.
Then, a 30 wt % hydrogen peroxide aqueous solution was added in
such an amount that the amount of hydrogen peroxide was 0.2 wt % of
the total amount of the aqueous solution to obtain an aqueous
solution (II) having a pH of 9.1.
2.2.3. Polishing of Blanket Wafer Having Copper Layer (Evaluation
of Copper Film Polishing Rate)
[0134] A blanket wafer (unpatterned wafer) having a copper layer as
a polishing target was chemically and mechanically polished using
the aqueous dispersion (I) and the aqueous solution (II)
synthesized as described above under two different conditions given
below using a chemical mechanical polishing system "EPO-112"
manufactured by Ebara Corporation and a polishing pad
"IC1000-050-(603)-(P)-S400J" manufactured by Nitta Haas
Incorporated. The aqueous dispersion (I) and the aqueous solution
(II) were separately supplied, and caused to come in contact with
each other and mixed on a platen.
2.2.3-1. Conditions 1
[0135] Supply rate of aqueous dispersion (I): 50 mL/min Supply rate
of aqueous solution (II): 250 mL/min Platen rotational speed: 100
rpm Head rotational speed: 80 rpm Head load: 140 g/cm.sup.2
Polishing time: 60 sec
2.2.3-2. Conditions 2
[0136] Supply rate of aqueous dispersion (I): 150 mL/min Supply
rate of aqueous solution (II): 150 mL/min
[0137] The platen rotational speed, the head rotational speed, the
head load, and the polishing time are the same as those of the
condition 1.
[0138] The removal rate of the copper film was calculated for each
wafer treated under the above conditions by dividing the difference
in the thickness of the copper film before and after the treatment
by the treatment time of the first treatment step. The removal rate
of the wafer polished under the conditions 1 was 12,000 .ANG./min,
and the removal rate of the wafer polished under the conditions 2
was 6,000 .ANG./min. The thickness of the copper film was
determined by measuring the sheet resistance by a four point probe
method using a resistivity processor (".SIGMA.-5" manufactured by
NPS Inc.) and calculating the thickness of the copper film from the
sheet resistance and the theoretical resistivity of copper
according the following equation.
Thickness of copper film (.ANG.)=sheet resistance
(.OMEGA./cm.sup.2) theoretical resistivity of copper
(.OMEGA./cm).times.10.sup.-8
2.2.4. Removal of Unnecessary Copper Film from Patterned Wafer
[0139] A patterned wafer ("SEMATECH #854" manufactured by
International Sematech; test wafer having various wiring patterns;
thickness of deposited copper film: 11,000 .ANG.) as a polishing
target was chemically and mechanically polished under the
conditions 1 (first polishing step) in "Polishing of blanket wafer
having copper layer" using the chemical mechanical polishing system
and the polishing pad used in "Polishing of blanket wafer having
copper layer. The wafer was then chemically and mechanically
polished under the conditions 2 (second polishing step). The
polishing time of the first polishing step was 45 seconds. In the
subsequent second polishing step, overpolishing was performed for
30 seconds after the polishing end point detected by reading a
change in torque from the platen current of the chemical mechanical
polishing system had been reached.
[0140] The thickness of the copper film remaining after the first
polishing step was calculated to be 2,000 .ANG. from the removal
rate of the copper film calculated by polishing experiments
conducted under the condition 1 in "Polishing of blanket wafer
having copper layer", the polishing time of the first polishing
step, and the initial thickness of copper deposited on the
polishing target. Note that the removal rate of the copper film
from the unpatterned wafer does not precisely coincide with the
removal rate of the copper film from the patterned wafer under the
same conditions.
[0141] The dishing value in the area having a wiring width of 100
.mu.m was measured for the polished wafer subjected to the above
two-step polishing using a high-precision surface profiler ("HRP"
manufactured by KLA-Tencor Corporation). As a result, the dishing
value was as small as 600 .ANG.. Similarly, the erosion value was
measured in the area in which the pattern of a wiring width of 9
.mu.m and a space of 1 .mu.m was continuously formed at a length of
1250 .mu.m in the direction perpendicular to the wiring. As a
result, the erosion value was as small as 400 .ANG..
[0142] The copper wiring was observed using a scanning electron
microscope. As a result, occurrence of corrosion was not
observed.
2.3. Examples 2 to 5
[0143] The aqueous dispersion (I) and the aqueous solution (II)
were prepared in the same manner as in Example 1 except for
changing the types and the amounts of the components of the aqueous
dispersion (I) and the aqueous solution (II) as shown in Table
1.
[0144] A blanket wafer having a copper layer was polished and an
unnecessary copper film was removed from a patterned wafer in the
same manner as in Example 1 except for using the resulting aqueous
dispersion (I) and aqueous solution (II) and changing the supply
rates of the aqueous dispersion (I) and the aqueous solution (II)
as shown in Table 2. The results are shown in Table 2. In Example
3, the first polishing step was performed until the polishing end
point detected from a change in torque of the polishing system was
reached, and the second polishing step was then performed for 30
seconds.
[0145] In Examples 2 to 4, ammonia was used as the pH adjusting
agent. Ammonia was added as 30 wt % aqueous ammonia. In Example 5,
potassium hydroxide was used as the pH adjusting agent. The
potassium hydroxide was added in a solid state.
[0146] In Table 1, the abbreviation for the surfactant indicates
the following compound.
DBS-K: potassium dodecylbenzenesulfonate DBS-A: ammonium
dodecylbenzenesulfonate SLA: ammonium lauryl sulfate
[0147] The symbol "-" in Table 1 indicates that the corresponding
component was not added.
TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4
Example 5 Aqueous Aqueous Aqueous Aqueous Aqueous Aqueous Aqueous
solution dispersion Aqueous dispersion Aqueous dispersion solution
Aqueous solution dispersion (I) (I) (I) solution (II) (I) solution
(II) (I) (II) dispersion (I) (II) (A) Abrasives Type Fumed silica
-- Colloidal -- Colloidal -- Fumed -- Composite -- silica silica
silica particle Amount (wt %) 2.0 -- 1.0 -- 5.0 -- 0.5 -- 3.0 --
(B) Quinolinic acid Amount (wt %) -- 0.5 -- -- 3.0 -- 0.5 -- -- --
(B') Compound having heterocyclic ring Type Quinaldinic --
Quinaldinic -- Quinaldinic -- -- -- Quinaldinic -- acid acid acid
acid Amount (wt %) 0.5 -- 1.0 -- 2.0 -- -- -- 1.0 -- (C) Polishing
rate improver Type -- -- -- (Ammonium -- Glycine -- Ethylene- --
Glycine persulfate) diamine Amount (wt %) -- -- -- -- -- 0.5 -- 0.4
-- 2.0 (D) Oxidizing agent Type -- Hydrogen -- Ammonium -- Ammonium
Hydrogen -- Hydrogen -- peroxide persulfate persulfate peroxide
peroxide Amount (wt %) -- 0.2 -- 5.0 -- 2.0 0.2 -- 0.2 --
Surfactant Type DBS-K -- DBS-A -- SLA -- DBS-K -- DBS-A -- Amount
(wt %) 0.1 -- 0.2 -- 0.5 -- 0.1 -- 0.2 -- pH adjusting agent Type
Potassium Potassium Ammonia -- Ammonia -- Ammonia -- Potassium --
hydroxide hydroxide hydroxide pH 10.0 9.1 10.5 4.1 10.2 5.6 9.0
11.7 9.2 6.2
2.4. Comparative Example 1
[0148] Chemical mechanical polishing was performed in the same
manner as in "Removal of unnecessary copper film from patterned
wafer" of Example 1 under the conditions of the second polishing
step without performing the first polishing step. After the
polishing end point detected from a change in torque of the
chemical mechanical polishing system was reached, overpolishing was
performed for 30 seconds.
[0149] The dishing value and the erosion value measured in the same
manner as in Example 1 were respectively 600 .ANG. and 400 .ANG.,
and occurrence of corrosion of the copper wiring was not observed
using a scanning electron microscope. However, the polishing time
from the start of polishing to the end point was 115 seconds (i.e.
the total polishing time was 145 seconds). Therefore, it was
confirmed that the method of Comparative Example 1 requires a
polishing time longer than that of the method of Example 1.
2.5. Comparative Example 2
[0150] Chemical mechanical polishing was performed in the same
manner as in "Removal of unnecessary copper film from patterned
wafer" of Example 2 under the conditions of the first polishing
step without changing the conditions. After the polishing end point
detected from a change in torque of the chemical mechanical
polishing system was reached, polishing was further performed for
30 seconds.
[0151] The dishing value and the erosion value measured in the same
manner as in Example 1 were respectively 1,200 .ANG. and 700 .ANG..
The resulting copper wiring was observed using a scanning electron
microscope. As a result, occurrence of corrosion was observed.
TABLE-US-00002 TABLE 2 Example 1 Example 2 Example 3 Example 4
Example 5 First polishing step Supply rate of aqueous dispersion
(I) 50 100 20 150 150 (mL/min) Supply rate of aqueous solution (II)
250 200 280 150 150 (mL/min) S(I-1)/S(II-1) 0.2 0.5 0.07 1.0 1.0
Removal rate of copper film from 12,000 18,000 21,000 15,000 13,000
unpatterned wafer (.ANG./min) Second polishing step Supply rate of
aqueous dispersion (I) 150 200 50 250 300 (mL/min) Supply rate of
aqueous solution (II) 150 100 250 50 0 (mL/min) S(I-2)/S(II-2) 1.0
2.0 0.2 5.0 .infin. Removal rate of copper film from 6,000 5,500
5,500 6,000 4,000 unpatterned wafer (.ANG./min) Polishing of
patterned wafer First polishing step Polishing time (sec) 45 30 40
35 45 Thickness of copper film remaining 2,000 2,000 0 (polished
2,250 1,250 after first polishing step (calculated until end value,
.ANG.) point was reached) Second polishing step Polishing time
(until end point, sec) 23 25 0 30 25 Overpolishing time (sec) 30 30
30 30 30 Total polishing time (sec) 98 85 70 95 100 Dishing (.ANG.)
600 300 700 900 550 Erosion (.ANG.) 400 350 450 500 380 Corrosion
None None None None None
[0152] Although only some embodiments of the invention have been
described in detail above, those skilled in the art will readily
appreciate that many modifications are possible in the embodiments
without departing from the novel teachings and advantages of this
invention. Accordingly, all such modifications are intended to be
included within the scope of this invention.
* * * * *