U.S. patent application number 11/727071 was filed with the patent office on 2007-07-26 for cmp abrasive, method for polishing substrate and method for manufacturing semiconductor device using the same, and additive for cmp abrasive.
Invention is credited to Toranosuke Ashizawa, Kouji Haga, Keizou Hirai, Naoyuki Koyama, Youiti Machii, Masato Yoshida.
Application Number | 20070169421 11/727071 |
Document ID | / |
Family ID | 27323685 |
Filed Date | 2007-07-26 |
United States Patent
Application |
20070169421 |
Kind Code |
A1 |
Koyama; Naoyuki ; et
al. |
July 26, 2007 |
CMP abrasive, method for polishing substrate and method for
manufacturing semiconductor device using the same, and additive for
CMP abrasive
Abstract
The present invention discloses a CMP abrasive comprising cerium
oxide particles, a dispersant, an organic polymer having an atom or
a structure capable of forming a hydrogen bond with a hydroxyl
group present on a surface of a film to be polished and water, a
method for polishing a substrate comprising polishing a film to be
polished by moving a substrate on which the film to be polished is
formed and a polishing platen while pressing the substrate against
the polishing platen and a polishing cloth and supplying the CMP
abrasive between the film to be polished and the polishing cloth, a
method for manufacturing a semiconductor device comprising the
steps of the above-mentioned polishing method, and an additive for
a CMP abrasive comprising an organic polymer having an atom or a
structure capable of forming a hydrogen bond with a hydroxyl group
present on a surface of a film to be polished, and water.
Inventors: |
Koyama; Naoyuki;
(Tsukuba-shi, JP) ; Haga; Kouji; (Hitachi-shi,
JP) ; Yoshida; Masato; (Tsukuba-shi, JP) ;
Hirai; Keizou; (Hitachiota-shi, JP) ; Ashizawa;
Toranosuke; (Hitachinaka-shi, JP) ; Machii;
Youiti; (Tsuchiura-shi, JP) |
Correspondence
Address: |
ANTONELLI, TERRY, STOUT & KRAUS, LLP
1300 NORTH SEVENTEENTH STREET
SUITE 1800
ARLINGTON
VA
22209-3873
US
|
Family ID: |
27323685 |
Appl. No.: |
11/727071 |
Filed: |
March 23, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10018188 |
Dec 18, 2001 |
|
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PCT/JP00/03891 |
Jun 15, 2000 |
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11727071 |
Mar 23, 2007 |
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Current U.S.
Class: |
51/298 ;
257/E21.23 |
Current CPC
Class: |
C09K 3/1463 20130101;
H01L 21/31053 20130101; H01L 21/30625 20130101; C09G 1/02 20130101;
C09K 3/1409 20130101 |
Class at
Publication: |
051/298 |
International
Class: |
C09K 3/14 20060101
C09K003/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 18, 1999 |
JP |
172821/1999 |
Jul 19, 1999 |
JP |
204842/1999 |
Nov 24, 1999 |
JP |
332221/1999 |
Claims
1. An additive for a CMP abrasive for polishing inorganic
insulating films having unevenness on a surface thereof, consisting
essentially of an organic polymer having an atom or a structure
capable of forming a hydrogen bond with a hydroxyl group present on
a surface of a film to be polished and containing at least one atom
having an unpaired electron in a molecular structure.
2. The additive for a CMP abrasive for polishing inorganic
insulating films having unevenness on a surface thereof according
to claim 1, wherein said organic polymer is a compound containing
either one or both of a nitrogen atom and an oxygen atom in a
molecular structure.
3. The additive for a CMP abrasive for polishing inorganic
insulating films having unevenness on a surface thereof according
to claim 1, wherein said organic polymer is a compound having an
adsorption ratio of 50% or more with respect to silicon oxide
particles of a specific surface area of 50 m.sup.2/g dispersed in
water of pH 6 to 8.
4. The additive for a CMP abrasive for polishing inorganic
insulating films having unevenness on a surface thereof according
to claim 1, wherein said organic polymer is a compound having an
adsorption ratio of 40% or more with respect to silicon nitride
particles of a specific surface area of 3.3 m.sup.2/g dispersed in
water of pH 6 to 8.
5. The additive for a CMP abrasive for polishing inorganic
insulating films having unevenness on a surface thereof according
to claim 1, wherein said organic polymer is polyvinyl
pyrrolidone.
6. The additive for a CMP abrasive for polishing inorganic
insulating films having unevenness on a surface thereof according
to claim 5, wherein said polyvinyl pyrrolidone has a weight average
molecular weight of 5,000 to 1,200,000.
Description
TECHNICAL FIELD
[0001] The present invention relates to a CMP (Chemical Mechanical
Polishing) abrasive used in a step for smoothing a surface of a
substrate, particularly in a step for smoothing an interlayer
insulating film and a BPSG (a boron phosphorus-doped silicon
dioxide film) film, a step for forming shallow trench isolation or
the like which are semiconductor element manufacturing techniques,
a method for polishing a substrate and a method for manufacturing a
semiconductor device using this CMP abrasive, and an additive for a
CMP abrasive.
BACKGROUND ART
[0002] Current ultra large scale integrated circuits tend to
enhance packaging density, and various microscopic processing
technologies have been studied and developed. Thus, the design-rule
has reached a sub half micron order. One of the technologies which
have been developed to satisfy requirements for such severe fining
is a CMP technology. This CMP technology can fully smooth a layer
to be exposed, reduce the load of an exposure technology, and
stabilize the yield in steps for manufacturing semi-conductor
devices. Thus, the CMP technology is an essential technology for
smoothing an interlayer insulating film and a BPSG film, and
performing shallow trench isolation, for example.
[0003] In steps for manufacturing semiconductor devices, as a CMP
abrasive for smoothing inorganic insulating films such as silicon
oxide insulating films formed by a plasma-CVD (Chemical Vapor
Deposition) method, a low pressure-CVD method or the like, fumed
silica series abrasives have been generally studied. The fumed
silica series abrasives are produced by causing grain growth by a
process of subjecting to pyrolysis of silica particles into silicic
tetrachloride or the like and by performing pH adjustment. However,
such an abrasive incurs technical problems that the polishing speed
for inorganic insulating films is not sufficient, causing a low
polishing speed in practical use.
[0004] In a conventional CMP technology for smoothing an interlayer
insulating film, there are technical problems that high level
smoothing cannot be realized in the entire surface of a wafer since
the dependency of polishing speed on the pattern of a film to be
polished on a substrate is great, the polishing speeds in projected
portions are largely differentiated due to the magnitude of the
pattern density difference or the size difference, and the
polishing of even recessed portions proceeds.
[0005] Further, in the CMP technology for smoothing the interlayer
film, it is necessary to finish polishing in the middle of the
interlayer film, and a method for controlling a process of
controlling the amount of polishing by polishing time has been
generally carried out. However, since the polishing speed is
remarkably changed not only due to the change in shapes of pattern
steps, but also due to the conditions of polishing cloth and the
like, there is the problem that process management is
difficult.
[0006] LOCOS (Local Oxidation of Silicon) had been used for element
isolation in integrated circuits in- the generation of a 0.5 .mu.m
or more design-rule. As the working size becomes finer thereafter,
technologies of narrower width of element isolation have been
required and shallow trench isolation is being used. In the shallow
trench isolation, the CMP is used for removing excess silicon oxide
films formed on a substrate and a stopper film having a slow
polishing speed is formed beneath the silicon oxide film to stop
the polishing. As a stopper film, silicon nitride and the like are
used, and preferably, the ratio of the polishing speed between the
silicon oxide film and the stopper film is large. Conventional
fumed silica series abrasives have a polishing speed ratio of as
small as about 3 between the above-mentioned silicon oxide film and
the stopper film, and the fumed silica abrasives have a problem
that they do not have properties endurable for practical use for
shallow trench isolation.
[0007] On the other hand, as the glass-surface abrasive for
photomasks, lenses, and the like, a cerium oxide abrasive has been
used. As cerium oxide particles have lower hardness than silica
particles or alumina particles, they tend to cause few scratches on
a surface to be polished so that they are useful for finishing
mirror polishing. However, since the cerium oxide abrasive for
glass surface polishing uses a dispersant containing a sodium salt,
it cannot be applied to an abrasive for semiconductors as it
is.
[0008] An object of the present invention is to provide a CMP
abrasive which is capable of polishing a surface to be polished
such as a silicon oxide insulating film at high speed without
causing scratches while attaining high level smoothing and has a
high storage stability.
[0009] Another object of the present invention is to provide a
method for polishing a substrate which is capable of polishing a
surface to be polished of a substrate at high speed without causing
scratches while attaining high level smoothing with easy process
control.
[0010] A further object of the present invention is to provide a
method for manufacturing a semiconductor device which is capable of
manufacturing a semiconductor device having a high reliability with
high productivity and good yield.
[0011] Still further object of the present invention is to provide
an additive for a CMP abrasive capable of polishing a surface to be
polished at high speed without causing scratches while attaining
high level smoothing, and particularly capable of providing the CMP
abrasive with an excellent storage stability.
DISCLOSURE OF THE INVENTION
[0012] The present invention relates to a CMP abrasive comprising
cerium oxide particles, a dispersant, an organic polymer having an
atom or a structure capable of forming a hydrogen bond with a
hydroxyl group present on a surface of the film to be polished, and
water.
[0013] Further, the present invention relates to the CMP abrasive
in which the organic polymer is a compound containing at least one
atom having an unpaired electron in the molecular structure.
[0014] Further, the present invention relates to the CMP abrasive
in which the organic polymer is a compound containing either one or
both of a nitrogen atom and an oxygen atom in the molecular
structure.
[0015] Further, the present invention relates to the CMP abrasive
in which the organic polymer is a compound having an adsorption
ratio of 50% or more with respect to silicon oxide particles of a
specific surface area of 50 m.sup.2/g dispersed in water of pH 6 to
8.
[0016] Further, the present invention relates to the CMP abrasive
in which the organic polymer is a compound having an adsorption
ratio of 40% or more with respect to silicon nitride particles of a
specific surface area of 3.3 m.sup.2/g dispersed in water of pH 6
to 8.
[0017] Further, the present invention relates to the CMP abrasive
in which the sedimentation speed for cerium oxide particles is 20
.mu.m/s or less.
[0018] The present invention also relates to the CMP abrasive in
which the organic polymer is polyvinyl pyrrolidone.
[0019] Further, the present invention relates to a method for
polishing a substrate comprising polishing a film to be polished by
moving a substrate on which the film to be polished was formed and
a polishing platen while pressing the substrate against the
polishing platen and a polishing cloth and supplying the CMP
abrasive between the film to be polished and the polishing
cloth.
[0020] Further, the present invention relates to a method for
manufacturing a semiconductor device comprising a step of polishing
a film to be polished by moving a substrate on which the film to be
polished is formed and a polishing platen while pressing the
substrate against the polishing platen and a polishing cloth and
supplying the CMP abrasive between the film to be polished and the
polishing cloth.
[0021] Further, the present invention relates to an additive for a
CMP abrasive comprising an organic polymer having an atom or a
structure capable of forming a hydrogen bond with a hydroxyl group
present on a surface of a film to be polished, and water.
BEST MODE FOR CARRYING OUT THE INVENTION
[0022] Cerium oxide particles in the present invention are obtained
by oxidizing cerium salts such as carbonate of cerium, nitrate of
cerium, sulfate of cerium and oxalate of cerium. The cerium oxide
particles preferably have a crystalline diameter of 5 to 300 nm
from the viewpoints of high speed polishing and low scratch
properties.
[0023] In the present invention, as methods for preparing cerium
oxide, calcination or an oxidation method of using hydrogen
peroxide, etc., can be used. Preferably, the calcining temperature
is 350.degree. C. or higher and 900.degree. C. or lower.
[0024] Since the cerium oxide particles manufactured by the above
method are agglomerated, it is preferred to mechanically grind
them. The grinding methods preferably include a dry grinding method
with a jet mill or the like and a wet grinding method with a
planetary bead mill or the like. The jet mill is described in, for
example, the Chemical Industry Theses, Vol. 6, No. 5 (1980) pp. 527
to 532.
[0025] The CMP abrasive according to the present invention can be
manufactured by first preparing a dispersion of cerium oxide
particles (hereinafter sometimes referred to as a "slurry")
comprising cerium oxide particles, a dispersant and water, and
adding an organic polymer having an atom or a structure capable of
forming a hydrogen bond with a hydroxyl group present on a surface
of a film to be polished (hereinafter sometimes referred to as
merely "organic polymer") therein. Here, the concentration of the
cerium oxide particles is not limited, but it is preferably in the
range of from 0.5 to 20% by weight from the viewpoint of handling
of the dispersion.
[0026] As the dispersants, there may be mentioned a water-soluble
anionic dispersant, a water-soluble nonionic dispersant, a
water-soluble cationic dispersant, and a water-soluble amphoteric
dispersant.
[0027] As the above-mentioned water-soluble anionic dispersants,
there may be mentioned, for example, lauryl sulfate
triethanolamine, lauryl sulfate ammonium, polyoxyethylene alkyl
ether sulfate triethanolamine and polycarboxylic acid series
polymer (for example, an alkali metal salt or ammonium salt of a
(co)polymer comprising (meth)acrylic acid, alkyl (meth)acrylate
used depending on necessity and vinyl monomer used depending on
necessity). Here, the (meth)acrylic acid in the present invention
means an acrylic acid and a methacrylic acid corresponding thereto,
and the alkyl (meth)acrylate means an alkyl acrylate and an alkyl
methacrylate corresponding thereto.
[0028] As the above-mentioned water-soluble nonionic dispersants,
there may be mentioned, for example, polyoxyethylene lauryl ether,
polyoxyethylene cetyl ether, polyoxyethylene stearyl ether,
polyoxyethylene oleyl ether, polyoxyethylene higher alcohol ether,
polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl
ether, polyoxyalkylene alkyl ether, polyoxyethylene derivative,
polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan
monopalmitate, polyoxyethylene sorbitan monostearate,
polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan
monooleate, polyoxyethylene sorbitan trioleate, tetraoleic acid
polyoxyethylene sorbitol, polyethylene glycol monolaurate,
polyethylene glycol monostearate, polyethylene glycol distearate,
polyethylene glycol monooleate, polyoxyethylene alkylamine,
polyoxyethylene hardened castor oil, and alkyl alkanolamide,
etc.
[0029] As the above-mentioned water-soluble cationic dispersants,
there may be mentioned, for example, coconut amine acetate and
stearylamine acetate, etc.
[0030] Further, as the above-mentioned water-soluble amphoteric
dispersants, there may be mentioned, for example, lauryl betaine,
stearyl betaine, lauryldimethyl amine oxide, and
2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine,
etc.
[0031] It is preferred that the amount of these dispersants to be
added is in the range of 0.01 part by weight or more and 2.0 parts
by weight or less based on 100 parts by weight of cerium oxide
particles from the viewpoint of improvement of dispersibility or
prevention of sedimentation of cerium oxide particles in a slurry,
and prevention of polishing scratches, and the like. The weight
average molecular weight (a value obtained by measuring with GPC
and calculated in terms of standard polystyrene) is preferably 100
to 50,000, more preferably 1,000 to 10,000. When the molecular
weight of the dispersant is less than 100, sufficient polishing
speed cannot be obtained in polishing a silicon oxide film or a
silicon nitride film, and when the molecular weight of the
dispersant exceeds 50,000, the viscosity thereof becomes high and
the storage stability of a CMP abrasive tends to be lowered.
[0032] In the methods of dispersing these cerium oxide particles
into water, in addition to the dispersion processing using a usual
stirrer, a homogenizer, an ultrasonic dispersing machine, a wet
type ball mill and the like can be used.
[0033] The average particle diameter of the thus prepared cerium
oxide particles in a slurry is preferably 0.01 .mu.m to 1.0 .mu.m.
When the average particle diameter of the cerium oxide particles is
less than 0.01 .mu.m, the polishing speed tends to become low, and
when the average particle diameter thereof exceeds 1.0 .mu.m, the
abrasive tends to cause scratches on a film to be polished.
[0034] Although organic polymers having an atom or a structure
capable of forming a hydrogen bond with a hydroxyl group present on
a surface of a film to be polished are not particularly limited as
long as they have a defined particular atom or structure, there may
be mentioned, for example, a compound containing at least one atom
having an unpaired electron in the molecular structure, or a
compound containing either one or both of a nitrogen atom and an
oxygen atom in the molecular structure.
[0035] Specifically, there may be mentioned polyvinyl acetal,
polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone,
polyvinyl pyrrolidone-iodine complex, polyvinyl
(5-methyl-2-pyrrolidinone), polyvinyl (2-piperidinone), polyvinyl
(3,3,5-trimethyl-2-pyrrolidinone), poly(N-vinylcarbazole),
poly(N-alkyl-2-vinylcarbazole), poly(N-alkyl-3-vinylcarbazole),
poly(N-alkyl-4-vinylcarbazole), poly(N-vinyl-3,6-dibromocarbazole),
polyvinyl phenyl ketone, polyvinyl acetophenone,
poly(4-vinylpyridine), poly(4-.beta.-hydroxyethylpyridine),
poly(2-vinylpyridine), poly(2-.beta.-hydroxyethylpyridine,
poly(4-vinylpyridinium salt), poly(.alpha.-methylstyrene-co-4-vinyl
pyridinium hydrochloride), poly(potassium
1-(3-sulfonyl)-2-vinylpyridinium betaine-co-p-styrene sulfonate),
poly(N-vinylimidazole), poly(4-vinyl imidazole), poly(5-vinyl
imidazole), poly(1-vinyl-4-methyloxazolidinone), polyvinyl
acetamide, polyvinyl methyl acetamide, polyvinyl ethyl acetamide,
polyvinyl phenyl acetamide, polyvinyl methyl propionamide,
polyvinyl ethyl propionamide, polyvinyl methyl isobutylamide,
polyvinyl methyl benzylamide, poly(meth)acrylic acid,
poly(meth)acrylic acid derivatives, poly(meth)acrylic acid ammonium
salts, polyvinyl alcohol, polyvinyl alcohol derivatives,
polyacrolein, polyacrylonitrile, polyvinyl acetate, poly(vinyl
acetate-co-methyl methacrylate), poly(vinyl acetate-co-vinyl
acrylate), poly(vinyl acetate-co-pyrrolidine), poly(vinyl
acetate-co-acetonitrile), poly(vinyl acetate-co-N,N-diallyl
cyanide), poly(vinyl acetate-co-N,N-diallyl amine), and poly(vinyl
acetate-co-ethylene), etc. Among these polymers, polyvinyl
pyrrolidone, poly(meth)acrylic acid derivative, and
poly(meth)-acrylic acid ammonium salts are preferable, and
polyvinyl pyrrolidone is particularly preferable.
[0036] The organic polymer is preferably a compound having an
adsorption ratio of 50% or more with respect to silicon oxide
particles dispersed in water of pH 6 to 8 and having a specific
surface area of 50 m.sup.2/g, from the viewpoint of performing
excellent polishing for shallow trench isolation. Further, from the
same viewpoint, it is preferably a compound having an adsorption
ratio of 40% or more to silicon nitride particles having a specific
surface area of 3.3 m.sup.2/g dispersed in water of pH 6 to 8.
[0037] The amount of these organic polymers to be added is
preferably in a range of 0.01 part by weight to 100 parts by
weight, more preferably 0.1 part by weight to 50 parts by weight,
and most preferably 1 part by weight to 50 parts by weight, based
on 100 parts by weight of cerium oxide particles from the viewpoint
of improvement in dispersibility of the cerium oxide particles in
CMP abrasive, prevention of sedimentation and prevention of
polishing scratches. Further, the weight average molecular weight
of the organic polymer (a value obtained by measuring with a GPC
and calculated in terms of standard polystyrene) is preferably
5,000 to 2,000,000, and more preferably 10,000 to 1,200,000.
[0038] In the present invention, a cerium oxide slurry comprising
cerium oxide particles, a dispersant, and water, and an additive
for a CMP abrasive comprising an organic polymer and water may be
divided, and may be stored and utilized as a two-liquid type CMP
abrasive.
[0039] When a substrate is polished by the above-mentioned CMP
abrasive, there can be employed a method having steps of separately
supplying the slurry and additive onto a polishing platen, and
mixing them thereon, a method having steps of mixing the slurry and
additive just before polishing and supplying the mixture onto a
polishing platen, etc.
[0040] To the CMP abrasive according to the present invention,
additives such as N,N-dimethylethanolamine,
N,N-diethylethanolamine, aminoethylethanolamine and the like may be
added.
[0041] In the CMP abrasive of the present invention, the
sedimentation speed of the cerium oxide particles is preferably 20
.mu.m/s or less from the viewpoint of workability.
[0042] An inorganic insulating film which is one of films to be
polished using a CMP abrasive of the present invention is formed by
a low-pressure CVD method, a plasma CVD method or the like.
[0043] Formation of a silicon oxide film by the low-pressure CVD
method uses monosilane: SiH.sub.4 as an Si source, and oxygen:
O.sub.2 as an oxygen source. A silicon oxide film can be obtained
by performing this SiH.sub.4--O.sub.2 series oxidation reaction at
a low temperature of 400.degree. C. or lower. Heat treatment is
optionally performed at a temperature of 1,000.degree. C. or lower
after the CVD process. When phosphorus: P is doped to attain the
surface smoothness by a high-temperature reflow process, an
SiH.sub.4--O.sub.2--PH.sub.3 series reaction gas is preferably
used.
[0044] The plasma CVD method-has such an advantage that a chemical
reaction, which requires a high temperature under usual thermal
equilibrium, can be performed at a low temperature. The plasma
generation method includes two types: a volume connection type and
an induction connection type. The reaction gases include an
SiH.sub.4--N.sub.2O series gas using SiH.sub.4 as an Si source and
N.sub.2O as an oxygen source, and TEOS--O.sub.2 series gas
(TEOS-plasma CVD method) using tetraethoxysilane (TEOS) as an Si
source. The temperature of a substrate is preferably in a range of
250.degree. C. to 400.degree. C., and the reaction pressure is
preferably in a range of 67 to 400 Pa. Thus, to the silicon oxide
film of the present invention, elements such as phosphorus and
boron may be doped.
[0045] Similarly, formation of silicon nitride film by the
low-pressure CVD method uses dichlorosilane: SiH.sub.2Cl.sub.2 as
an Si source and ammonia: NH.sub.3 as a nitrogen source. A silicon
nitride film can be obtained by performing this
SiH.sub.2Cl.sub.2--NH.sub.3 series oxidation reaction at a high
temperature of 900.degree. C.
[0046] In the plasma CVD method, the reaction gases include an
SiH.sub.4--NH.sub.3 series gas using SiH.sub.4 as an Si source and
NH.sub.3 as a nitrogen source. The temperature of a substrate is
preferably 300.degree. C. to 400.degree. C.
[0047] As a substrate, a semiconductor substrate, that is a
semiconductor substrate in a phase of circuit elements and a wiring
pattern formed thereon, or circuit elements formed thereon and the
like on which a silicon oxide film layer or a silicon nitride film
layer is formed can be used. By polishing the silicon oxide film or
silicon nitride film formed on such a semiconductor substrate with
a CMP abrasive, the projections and recessions of a surface of the
silicon oxide film layer are removed and a smooth surface over the
entire surface of the semiconductor substrate can be obtained.
[0048] Further, it can be also used for shallow trench isolation.
To use it for shallow trench isolation, the ratio between the
silicon oxide film polishing speed and the silicon nitride film
polishing speed, that is the silicon oxide film polishing speed/the
silicon nitride film polishing speed is preferably 10 or more. In
the case where this ratio is less than 10, the difference between
the silicon oxide film polishing speed and the silicon nitride film
polishing speed is small, and stopping the polishing at a
predetermined position tends to become difficult in the shallow
trench isolation. In the case where this ratio is 10 or more, the
silicon nitride film polishing speed is further reduced, rendering
stoppage of polishing easy, thus making it more suitable for
shallow trench isolation.
[0049] To use the CMP abrasive for the shallow trench isolation, it
is preferred that generation of scratches during polishing be
small.
[0050] Here, as a polishing device, a general polishing device
having a holder which supports a semiconductor substrate, and a
platen to which a polishing cloth (pad) is adhered (a motor whose
number of revolutions is changeable is attached) can be used.
[0051] As a polishing cloth, a general nonwoven fabric, an expanded
polyurethane, a porous fluorine resin or the like can be used
without specific limitation. Further, it is preferred that a groove
in which the CMP abrasive is stored be formed in the polishing
cloth.
[0052] Although the polishing conditions are not limited, the
rotational speed of the platen is preferably low as 200 min.sup.-1
or less so that the semiconductor substrate does not come off, and
the pressure applied to the semiconductor substrate is preferably
10.sup.5 Pa or less so that no scratches will be present after
polishing.
[0053] During polishing, a slurry is continuously supplied onto a
polishing cloth with a pump or the like. Although the amount of a
slurry supplied is not limited, it is preferred that the surface of
the polishing cloth be always covered with a slurry.
[0054] It is preferred that after the polished semiconductor
substrate is washed well in running water, water drops attached
onto the semiconductor substrate be shaken off with a spin dryer or
the like and dried.
[0055] Thus, after the smoothed shallow trench is formed, an
aluminum wiring is formed on a silicon oxide insulating film layer,
and a silicon oxide insulating film is formed between the wirings
and on the wiring by the above-mentioned process again, then
polishing is performed using the CMP abrasive so that the
projections and recessions on a surface of the insulating film are
removed to form a smooth surface over the entire surface of the
semiconductor substrate. By repeating these steps for predetermined
times, a semiconductor having a desired number of layers is
manufactured.
[0056] The CMP abrasive according to the present invention can
polish not only a silicon oxide film formed on a semiconductor
substrate, but also a silicon oxide film formed on a wiring board
having predetermined wiring, an inorganic insulating film such as
glass, silicon nitride, etc., a film principally containing
polysilicon, Al, Cu, Ti, TiN, W, Ta, TaN and the like, an optical
glass such as a photomask, a lens, and a prism, an inorganic
conducting film such as ITO, an optical integrated circuit, an
optical switching element, an optical waveguide constituted by
glass and a crystalline material, an end surface of optical fiber,
an optical single crystal such as a scintillator, a solid laser
single crystal, a sapphire substrate for a blue laser LED, a
semiconductor single crystal such as SiC, GaP and GaAs, a glass
substrate for a magnetic disk, a magnetic head and the like.
EXAMPLE
[0057] The present invention will be described below in detail
using Examples, but the present invention is not limited
thereto.
EXAMPLE 1
(Preparation of Cerium Oxide Particles)
[0058] 2 kg of a cerium carbonate hydrate was placed into a vessel
made of alumina, and calcined at a temperature of 800.degree. C.
for 2 hours in the air to obtain about 1 kg of yellowish white
powder. This powder was phase-identified by the X-ray
diffractometry whereby it was confirmed to be cerium oxide. The
diameter of the calcined powder particles was 30 to 100 .mu.m. The
surface of the calcined powder particle was observed with a
scanning type electron microscope, and then particle boundaries of
the cerium oxide were observed. A primary-particle diameter of a
cerium oxide surrounded by the grain boundary was measured. The
median value and the maximum value in the volume distribution were
190 nm and 500 nm, respectively.
[0059] 1 kg of cerium oxide powder was dry-ground with a jet mill.
The observation of the ground particles was performed with a
scanning type electron microscope. As a result, not only small
particles having the same size as the primary particle diameter,
but also remaining not-ground large particles of 1 to 3 .mu.m and
remaining not-ground particles of 0.5 to 1 .mu.m were found to be
mixed with each other.
(Measurement of Adsorption of Organic Polymer to Silicon Oxide
Particles)
[0060] 100 g of a testing water having a concentration of 500 ppm
polyvinyl pyrrolidone with a weight average molecular weight of
25,000 was adjusted to pH 7.0, and 50 g of the testing water was
measured and taken out. Then, 0.5 g of silicon oxide particles
having a specific surface area of 50 m.sup.2/g were added to the
water and shaken reciprocally for 10 minutes. After that,
centrifugal separation was conducted at 15,000 min.sup.-1 for 5
minutes to obtain a supernatant liquid. Subsequently, the total
amount of organic carbon (TOC) in this supernatant (liquid A) and
that of the remaining testing water (liquid B) not mixed with
silicon oxide particles were measured respectively with a total
organic carbon meter TOC-5000 manufactured by Shimadzu Corp. The
measurement of TOC was determined by subtracting the amount of the
inorganic carbon (IC) from the total amount of carbon (TC).
[0061] Further, silica particles, were similarly mixed with pure
water and shaken, and after centrifugal separation, the TOC value
of the supernatant was set to a blank value. The TOC values of the
liquids A and B were defined as TOCA and TOCB, respectively, and
the adsorbed amount was calculated by the expression of
(TOCB-TOCA/TOCA). As a result, the adsorbed amount of
polypyrrolidone to the silicon oxide particles was 78%.
(Adsorption of Organic Polymer to Silicon Nitride Particles)
[0062] 100 g of testing water having a concentration of 50 ppm
polyvinyl pyrrolidone with a weight average molecular weight of
25,000 was adjusted to pH 7.0, and 50 g of the testing water was
measured and taken out. Then, 4 g of silicon oxide particles having
a specific surface area of 3.3 m.sup.2/g were added to the water
and shaken reciprocally for 10 minutes. After that, centrifugal
separation was conducted at 15,000 min.sup.-1 for 5 minutes to
obtain a supernatant. Subsequently, the total amount of organic
carbon (TOC) in the supernatant (liquid C) and that of the
remaining testing water (liquid D) not mixed with silicon oxide
particles were measured, respectively, with a total organic carbon
meter TOC-5000 manufactured by Shimadzu Corp. The measurement of
TOC was determined by subtracting the amount of inorganic carbon
(IC) from the total amount of carbon (TC).
[0063] Further, silica particles were similarly mixed with pure
water and shaken, and after centrifugal separation, the TOC value
of the supernatant was set to a blank value. The TOC values of the
liquids C and D were defined as TOCC and TOCD respectively, and the
adsorbed amount was calculated by an expression of
(TOCD-TOCC/TOCD). As a result, the adsorbed amount of polyvinyl
pyrrolidone to the silicon oxide particles was 53%.
(Preparation of Cerium Oxide Slurry)
[0064] 1 kg of the above-prepared cerium oxide particles, 23 g of
an aqueous ammonium polyacrylate solution (40% by weight) and 8,977
g of deionized water were mixed and ultrasonic dispersion was
performed for 10 minutes while stirring. The obtained slurry was
filtered with a 1 micron filter, and a slurry (solid content: 5% by
weight) was obtained by further adding deionized water. The pH of
this slurry was 8.3. To measure the slurry particles with a laser
diffraction type grain size distribution meter, the particles were
diluted to an appropriate concentration. As a result, the median
value of the particle diameters was 190 nm.
[0065] Further, 600 g of the cerium oxide slurry (solid content: 5%
by weight), 3 g of polyvinyl pyrrolidone with a weight average
molecular weight of 25,000 as an additive and 2,397 g of deionized
water were mixed to prepare a CMP abrasive (solid content: 1% by
weight). The pH of this CMP abrasive was 8.0. To measure the
particles in the CMP abrasive with a laser diffraction type grain
size distribution meter, the particles were diluted to an
appropriate concentration. As a result, the median value of the
particle diameters was 190 nm.
(Measurement of Sedimentation Speed)
[0066] 500 g of the cerium oxide slurry prepared in the above
section "preparation of cerium oxide slurry" was placed into an
Andreasen pippette and left to stand. Immediately after the
operation, 10 ml of slurry was sampled from a position of 20 cm
below the surface of the cerium oxide slurry, and the concentration
thereof was measured.
[0067] The same operation was performed after 3 hours, 6 hours, 24
hours, 2 days, 5 days, 8 days, 13 days, 20 days, 30 days, 70 days
and 120 days.
[0068] As a result, the average sedimentation speed of the cerium
oxide slurry was 0.11 .mu.m/s.
[0069] Here, the average sedimentation speed means a value obtained
by dividing 20 cm by the time required for the concentration
measured in the above-mentioned manner to reduce into the half of
the initial 5% by weight, or 2.5% by weight.
[0070] The time required at this time was 21 days. Further, a
concentration measured after 6 days was 5% by weight, which was not
changed. Thus, the maximum sedimentation speed of this cerium oxide
slurry is 9 .mu.m/s or less. That is, the sedimentation speed of
all the cerium oxide particles contained in this cerium oxide
slurry is 9 .mu.m/s or less.
(Polishing of Insulating Film Layer)
[0071] After an Al wiring line portion having a line/space width of
0.05 to 5 mm and a height of 1,000 nm was formed on an Si substrate
having a diameter of 200 mm, a pattern wafer on which a 2,000 nm
thick silicon oxide film was formed by the TEOS-plasma CVD method
was prepared.
[0072] The above-mentioned pattern wafer was set on a holder to
which an adsorption pad for mounting a substrate to be held was
adhered, and the holder was placed on a platen having a diameter of
600 mm, to which a polishing pad made of a porous urethane resin
was adhered with the insulating film surface down, and then the
working load was set to 30 kPa.
[0073] The platen and the wafer were rotated for 2 minutes at a
rotational speed of 50 min.sup.-1 while dropping the
above-mentioned cerium oxide abrasive (solid content: 1% by weight)
on the platen at a dropping speed of 200 ml/min, thereby polishing
the insulating film.
[0074] After the polished wafer was washed well with pure water, it
was dried. Similarly, the above-mentioned pattern wafers were
polished for polishing time of 3 minutes, 4 minutes, 5 minutes and
6 minutes.
[0075] Using an optical interference type film thickness measuring
device, the thickness difference before and after polishing were
measured and the polishing speed was calculated.
[0076] Polishing speed of a line portion having a line/space width
of 1 mm is defined as R.sub.1, the polishing speed of a line
portion having a line/space width of 3 mm as R.sub.3, and the
polishing speed of a line portion having a line/space width of 5 mm
as R.sub.5. The polishing speed ratios R.sub.5/R.sub.1 and
R.sub.3/R.sub.1 became larger for polishing time between polishing
time of 2 and 4 minutes according to the increase in the polishing
time, and became substantially constant between polishing time of 4
and 6 minutes.
[0077] In the case of 4 minutes polishing time where the pattern
width dependency of the polishing speed becomes constant, the
polishing speed R.sub.1 for a line portion having a line/space
width of 1 mm was 344 nm/min (amount of polishing: 1,377 nm), the
polishing speed R.sub.3 for a line portion having a line/space
width of 3 mm was 335 nm/min (amount of polishing: 1,338 nm), and
the polishing speed R.sub.5 for a line portion having a line/space
width of 5 mm was 315 nm/min (amount of polishing: 1,259 nm), and
the polishing speed ratios R.sub.5/R.sub.1 and R.sub.3/R.sub.1 were
0.91 and 0.97, respectively.
[0078] The amounts of polishing of line portions in each line/space
width for the polishing time of 5 minutes and 6 minutes were
substantially the same as in the case of 4 minutes, and it was
found that no polishing advanced at all after 4 minutes.
EXAMPLE 2
(Preparation of Cerium Oxide Particles)
[0079] 2 kg of cerium carbonate hydrate was placed into a vessel
made of platinum, and calcined at a temperature of 800.degree. C.
for 2 hours in the air to obtain about 1 kg of yellowish white
powder. This powder was phase-identified by the X-ray
diffractometry, whereby the powder was confirmed to be cerium
oxide. The diameters of the calcined powder particles were 30 to
100 .mu.m. The surface of the calcined powder particles was
observed with a scanning type electron microscope, and particle
boundaries of the cerium oxide were observed. A primary particle
diameter of a cerium oxide particle surrounded by the grain
boundary was measured. The median value and the maximum value in
the volume distribution were 190 nm and 500 nm, respectively.
[0080] 1 kg of cerium oxide powder was dry-ground with a jet mill.
The observation of the ground particles was performed with a
scanning type electron microscope. As a result, not only small
particles having the same size as the primary particle diameter,
but also remaining not-ground large particles of 1 to 3 .mu.m and
remaining not-ground particles of 0.5 to 1 .mu.m were found to be
mixed with each other.
(Preparation of Cerium Oxide Slurry)
[0081] 1 kg of the prepared cerium oxide particles, 23 g of an
aqueous ammonium polyacrylate solution (40% by weight) and 8,977 g
of deionized water were mixed and ultrasonic dispersion was
performed for 10 minutes while stirring. The obtained slurry was
filtered with a 1 micron filter, and a slurry (solid content: 5% by
weight) was obtained by adding deionized water. The pH of this
slurry was 8.3. To measure the slurry particles with a laser
diffraction type grain size distribution meter, the particles were
diluted to an appropriate concentration. As a result, the median
value of the particle diameters was 190 nm.
[0082] Further, 600 g of the cerium oxide slurry (solid content: 5%
by weight), 3 g of polyvinyl pyrrolidone as an additive and 2,397 g
of deionized water were mixed to prepare a CMP abrasive (solid
content: 1% by weight). The pH of this CMP abrasive was 8.0. To
measure the particles in the CMP abrasive with a laser diffraction
type grain size distribution meter, the particles were diluted to
an appropriate concentration. As a result, the median value of the
particle diameters was 190 nm.
(Polishing of Shallow Trench Separation Layer)
[0083] Projected portions each having a square section of a side of
350 nm to 0.1 mm and recessed portions each having a depth of 400
nm were formed on an Si substrate having a diameter of 200 mm, and
a pattern wafer having the projected portion density of 2 to 40%
was prepared.
[0084] A 100 nm thick nitrogen oxide film was formed on the
projected portions and a 500 nm thick silicon oxide film was formed
thereon by the TEOS-plasma CVD method.
[0085] The above-mentioned pattern wafer was set on a holder to
which an adsorption pad for mounting a substrate to be held was
adhered, and the holder was placed on a platen having a diameter of
600 mm to which a polishing pad made of a porous urethane resin was
adhered with the insulating film surface down, and further the
working load was set to 30 kPa.
[0086] The platen and the wafer were rotated for 4 minutes at a
rotational speed of 50 min.sup.-1 while dropping the
above-mentioned CMP abrasive (solid content: 1% by weight) on the
platen at a dropping speed of 200 ml/min, thereby polishing the
insulating film. After the polished wafer was washed well with pure
water, it was dried. Similarly, the above-mentioned pattern wafers
were polished by setting the polishing time to 5 minutes and 6
minutes.
[0087] Using an optical interference type film thickness measuring
device, the film thicknesses before and after polishing were
measured. At the polishing time of 4 minutes, the entire silicon
oxide film on the projected portions was polished, and when the
nitrogen oxide film was exposed, the polishing stopped. Then the
film thickness before and after polishing was measured and the
polishing speed was calculated. The polishing speeds on projected
portions having 0.1 mm square and densities of 40% and 2% are
defined as R.sub.0.1-40 and R.sub.0.1-2, respectively, and the
polishing speeds on projected portions having 350 nm square and
densities of 40% and 2% are defined as R.sub.350-40 and
R.sub.350-2, respectively. In the case where polishing time was set
to 4 minutes, R.sub.0.1-40, R.sub.0.1-2, R.sub.350-40 and
R.sub.350-2 were 126 nm/min, 135 nm/min, 133 nm/min, and 137
nm/min, and R.sub.0.1-40/R.sub.350-40 and R.sub.0.1-2/R.sub.350-2
were 0.95 and 0.99, respectively. Thus, there was no pattern width
dependency. Further, the amounts of polishing in the projected
portions in each pattern width in the case of polishing time of 5
minutes and 6 minutes were substantially the same as in the case of
4 minutes, and it was found that no polishing advanced at all after
4 minutes.
Comparative Example 1
(Preparation of Cerium Oxide Particles)
[0088] 2 kg of cerium carbonate hydrate was placed into a vessel
made of platinum, and calcined at a temperature of 800.degree. C.
for 2 hours in the air to obtain about 1 kg of yellowish white
powder. This powder was phase-identified by an X-ray
diffractometry, whereby the powder was confirmed to be cerium
oxide. The diameter of the calcined powder particle was 30 to 100
.mu.m. A surface of the calcined powder particle was observed with
a scanning type electron microscope, and particle boundaries in the
cerium oxide were observed. A primary particle diameter of a cerium
oxide surrounded by the grain boundary was measured. The median
value and the maximum value in the volume distribution were 190 nm
and 500 nm, respectively.
[0089] 1 kg of cerium oxide powder was dry-ground with a jet mill.
The observation of the ground particles was performed with a
scanning type electron microscope. As a result, not only small
particles having the same size as the primary particle diameter,
but also remaining not-ground large particles of 1 to 3 .mu.m and
remaining not-ground particles of 0.5 to 1 .mu.m were found to be
mixed with each other.
(Preparation of Cerium Oxide Slurry)
[0090] 1 kg of the prepared cerium oxide particles, 23 g of an
aqueous ammonium polyacrylate solution (40% by weight) and 8,977 g
of deionized water were mixed and ultrasonic dispersion was
performed for 10 minutes while stirring. The obtained slurry was
filtered with a 1 micron filter, and a cerium oxide slurry (solid
content: 5% by weight) was obtained by further adding deionized
water. The pH of this cerium oxide slurry was 8.3.
[0091] 600 g of the above-mentioned cerium oxide slurry (solid
content: 5% by weight), and 2,400 g of deionized water were mixed
to prepare an abrasive (solid content: 1% by weight). The pH of
this abrasive was 7.4. To measure the particles in the abrasive
with a laser diffraction type grain size distribution meter, the
particles were diluted to an appropriate concentration. As a
result, the median value of the particle diameters was 190 nm.
(Polishing of Insulating Film)
[0092] After an Al wiring line portion having a line/space width of
0.05 to 5 mm and a height of 1,000 nm was formed on an Si substrate
having a diameter of 200 mm, a pattern wafer on which a 2,000 nm
thick silicon oxide film was formed by the TEOS-plasma CVD method
was prepared.
[0093] The pattern wafer was set on a holder to which an adsorption
pad for mounting a substrate to be held was adhered, and the holder
was placed on a platen having a diameter of 600 mm to which a
polishing pad made of a porous urethane resin was adhered with the
insulating film surface down, and then the working load was set to
30 kPa.
[0094] The platen and the wafer were rotated for 1 minute at a
rotational speed of 50 min.sup.-1 while dropping the
above-mentioned cerium oxide slurry (solid content: 1% by weight)
on the platen at a dropping speed of 200 ml/min, thereby polishing
the insulating film. After the polished wafer was washed well with
pure water, it was dried. Similarly, the above-mentioned pattern
wafers were polished by setting the polishing times to 1.5 minutes
and 2 minutes.
[0095] Polishing speed of a line portion having a line/space width
of 1 mm is defined as R.sub.1, the polishing speed of a line
portion having a line/space width of 3 mm as R.sub.3, and the
polishing speed of a line portion having a line/space width of 5 mm
as R.sub.5. The polishing speed ratios R.sub.5/R.sub.1 and
R.sub.3/R.sub.1 became substantially constant between polishing
time of 1 and 2 minutes.
[0096] In the case of 1.5 minutes polishing time where the pattern
width dependency of the polishing speed becomes constant, the
polishing speed R.sub.1 for a line portion having a line/space
width of 1 mm was 811 nm/min (amount of polishing: 1,216 nm), the
polishing speed R.sub.3 for a line portion having a line/space
width of 3 mm was 616 nm/min (amount of polishing: 924 nm), and the
polishing speed R.sub.5 for a line portion having a line/space
width of 5 mm was 497 nm/min (amount of polishing: 746 nm), and the
polishing speed ratios R5/R.sub.1 and R.sub.3/R.sub.1 were 0.61 and
0.76 respectively. In the polishing time of 2 minutes, polishing
advanced to the Al wiring which is a ground under the silicon oxide
film in a line portion of the line/space width of 0.05 to 1 mm.
Comparative Example 2
(Polishing of Insulating Film)
[0097] After an Al wiring line portion having a line/space width of
0.05 to 5 mm and a height of 1,000 nm was formed on an Si substrate
having a diameter of 200 mm, a pattern wafer on which a 2,000 nm
thick silicon oxide film was formed by the TEOS-plasma CVD method
was prepared.
[0098] 2 minutes polishing was performed using a commercially
available silica slurry in the same manner as in the
above-mentioned Examples. The pH of this commercially available
silica slurry is 10.3 and the slurry contains 12.5% by weight of
SiO.sub.2 particles. The polishing conditions were set to the same
as in Example 1. As in the case of Example 1, the above-mentioned
pattern wafers were polished by setting the polishing time to 3
minutes, 4 minutes, 5 minutes, and 6 minutes.
[0099] Using an optical interference type film thickness measuring
device, the thickness difference before and after polishing was
measured and the polishing speed was calculated. The polishing
speed of a line portion having a line/space width of 1 mm is
defined as R.sub.1, the polishing speed of a line portion having a
line/space width of 3 mm as R.sub.3, and the polishing speed of a
line portion having a line/space width of 5 mm as R.sub.5. The
polishing speed ratios R.sub.5/R.sub.1 and R.sub.3/R.sub.1 became
larger between the polishing time of 2 and 5 minutes according to
the increase in the polishing time, and became substantially
constant between the polishing time of 5 and 6 minutes.
[0100] In the case of 5 minutes polishing time where the pattern
width dependency of the polishing speed becomes constant, the
polishing speed R.sub.1 for a line portion having a line/space
width of 1 mm was 283 nm/min (amount of polishing: 1,416 nm), the
polishing speed R.sub.3 for a line portion having a line/space
width of 3 mm was 218 nm/min (amount of polishing: 1,092 nm), and
the polishing speed R.sub.5 for a line portion having a line/space
width of 5 mm was 169 nm/min (amount of polishing: 846 nm), and the
polishing speed ratios R.sub.5/R.sub.1 and R.sub.3/R.sub.1 were
0.60 and 0.77, respectively. The polishing speed of line portions
in each line/space width for the polishing time of 6 minutes was
substantially the same as in the case of 5 minutes, and it was
found that the polishing advanced at the same polishing speed after
the pattern width dependency of the polishing speed became
constant.
INDUSTRIAL APPLICABILITY
[0101] The CMP abrasive according to the present invention can
polish a surface to be polished such as a silicon oxide insulating
film or the like at high speed without causing scratches while
attaining high level smoothing, and has an excellent storage
stability.
[0102] The method for polishing a substrate according to the
present invention can polish a surface to be polished at high speed
without causing scratches while attaining high level smoothing.
[0103] The method for manufacturing a semiconductor device
according to the present invention can manufacture a semiconductor
device having a high degree of reliability with high productivity
and good yield.
[0104] The additive for the CMP abrasive according to the present
invention can polish a surface of a film to be polished at high
speed without causing scratches while attaining high level
smoothing, and particularly provide the CMP abrasive with excellent
storage stability.
* * * * *