U.S. patent application number 12/591210 was filed with the patent office on 2010-03-04 for cleaning liquid used in process for forming dual damascene structure and a process for treating substrate therewith.
Invention is credited to Kazumasa Wakiya, Shigeru Yokoi.
Application Number | 20100051582 12/591210 |
Document ID | / |
Family ID | 32262578 |
Filed Date | 2010-03-04 |
United States Patent
Application |
20100051582 |
Kind Code |
A1 |
Yokoi; Shigeru ; et
al. |
March 4, 2010 |
Cleaning liquid used in process for forming dual damascene
structure and a process for treating substrate therewith
Abstract
It is disclosed a cleaning liquid used in a process for forming
a dual damascene structure comprising steps of etching a low
dielectric layer (low-k layer) accumulated on a substrate having
thereon a metallic layer to form a first etched-space; charging a
sacrifice layer in the first etched-space; partially etching the
low dielectric layer and the sacrifice layer to form a second
etched-space connected to the first etched-space; and removing the
sacrifice layer remaining in the first etched-space with the
cleaning liquid, wherein the cleaning liquid comprises (a) 1-25
mass % of a quaternary ammonium hydroxide, such as TMAH and
choline, (b) 30-70 mass % of a water soluble organic solvent, and
(c) 20-60 mass % of water. The cleaning liquid attains in a well
balanced manner such effects that a sacrifice layer used for
forming a dual damascene structure is excellently removed, and a
low dielectric layer is not damaged upon formation of a metallic
wiring on a substrate having a metallic layer (such as a Cu layer)
and the low dielectric layer formed thereon.
Inventors: |
Yokoi; Shigeru;
(Kanagawa-ken, JP) ; Wakiya; Kazumasa;
(Kanagawa-ken, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
1030 15th Street, N.W.,, Suite 400 East
Washington
DC
20005-1503
US
|
Family ID: |
32262578 |
Appl. No.: |
12/591210 |
Filed: |
November 12, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12379099 |
Feb 12, 2009 |
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12591210 |
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11473030 |
Jun 23, 2006 |
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12379099 |
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10657177 |
Sep 9, 2003 |
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11473030 |
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Current U.S.
Class: |
216/41 ;
510/175 |
Current CPC
Class: |
C11D 11/0047 20130101;
H01L 21/31138 20130101; C11D 7/32 20130101; H01L 21/31144 20130101;
H01L 21/76807 20130101 |
Class at
Publication: |
216/41 ;
510/175 |
International
Class: |
B44C 1/22 20060101
B44C001/22; C11D 7/32 20060101 C11D007/32 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 9, 2002 |
JP |
2002-262565 |
Claims
1. A cleaning liquid used in a process for forming a dual damascene
structure comprising steps of etching a low dielectric layer
accumulated on a substrate having thereon a metallic layer to form
a first etched-space; charging a sacrifice layer in the first
etched-space; partially etching the low dielectric layer and the
sacrifice layer to form a second etched-space connected to the
first etched-space; and removing the sacrifice layer remaining in
the first etched-space with the cleaning liquid, wherein the
cleaning liquid comprises (a) 1-25 mass % of a quaternary ammonium
hydroxide represented by the following general formula (I), (b)
30-70 mass % of a water soluble organic solvent, and (c) 20-60 mass
% of water: ##STR00005## wherein R.sub.1, R.sub.2, R.sub.3 and
R.sub.4 each independently represents an alkyl group having 1-4
carbon atoms or a hydroxyalkyl group having 1-4 carbon atoms.
2. The cleaning liquid as claimed in claim 1, wherein the sacrifice
layer comprises a spin-on-glass material.
3. The cleaning liquid as claimed in claim 2, wherein the
spin-on-glass material contains a light absorbing substance.
4. The cleaning liquid as claimed in claim 1, wherein component (a)
is tetramethylammonium hydroxide and/or
(2-hydroxyethyl)trimethylammonium hydroxide.
5. The cleaning liquid as claimed in claim 1, wherein component (b)
is dimethyl sulfoxide.
6. The cleaning liquid as claimed in claim 1, wherein the cleaning
liquid comprises 8-12 mass % of component (a), 40-60 mass % of
component (b), and 30-50 mass % of component (c).
7. The cleaning liquid as claimed in claim 1, wherein the cleaning
liquid further comprises (d) a mercapto group-containing compound,
and/or (e) a quaternary ammonium hydroxide represented by the
following general formula (II), with the proviso that component (e)
differs from component (a): ##STR00006## wherein R.sub.5, R.sub.6,
R.sub.7 and R.sub.8 each independently represents an alkyl group
having 1-20 carbon atoms or a hydroxyalkyl group having 1-20 carbon
atoms, provided that at least one of R.sub.5, R.sub.6, R.sub.7 and
R.sub.8 represents an alkyl group having 10 or more carbon atoms,
or at least two of R.sub.5, R.sub.6, R.sub.7 and R.sub.8 each
independently represents a hydroxyalkyl group having 2-5 carbon
atoms.
8. A process for treating a substrate having a dual damascene
structure comprising steps of: etching a low dielectric layer
accumulated on a substrate having thereon a metallic layer to form
a first etched-space; charging a sacrifice layer in the first
etched-space; partially etching the low dielectric layer and the
sacrifice layer to form a second etched-space connected to the
first etched-space; and bringing the sacrifice layer remaining in
the first etched-space in contact with a cleaning liquid as claimed
in any one of claims 1-7 to remove the sacrifice layer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a cleaning liquid used in a
process for forming a dual damascene structure and a method for
treating a substrate therewith. The cleaning liquid of the
invention is favorably used in production of a semiconductor
device, such as IC and LSI.
[0003] 2. Description of the Related Art
[0004] A semiconductor device, such as IC and LSI, is produced in
the following process. A photoresist is uniformly coated on an
electroconductive metallic film, an insulating film or a low
dielectric material film formed on a substrate, such as a silicon
wafer, by CVD vapor deposition process or the like. The photoresist
selectively subjected to exposure and development to form a
photoresist pattern. The electroconductive metallic film, the
insulating film or the low dielectric material film formed by CVD
vapor deposition is selectively etched by using the photoresist
pattern as a mask to form a minute circuit, and the photoresist
layer thus becoming unnecessary is then removed with a remover
liquid.
[0005] It is a trend in recent years that wiring circuits are
becoming minute and multilayered as integration degree of
semiconductor devices increases and chip size reduces, in which
there arise problems in semiconductor devices, i.e., resistance of
metallic films (wiring resistance) and wiring delay caused by
wiring capacities. Accordingly, there are proposals of using
metals, such as copper (Cu), having resistance smaller than that of
aluminum (Al) having been mainly employed as a wiring material, and
in recent years, two kinds of devices are being used, i.e., devices
using an Al wiring (a metallic wiring using Al as a major
component, such as Al and an Al alloy) and devices using a copper
wiring (a metallic wiring using Cu as a major component).
[0006] Upon forming a Cu metallic wiring, in particular, a process
is used in which a Cu multilayer wiring is formed without etching
Cu by using a dual damascene process, owing to the low etching
resistance of Cu. Various kinds of dual damascene processes have
been proposed, an example of which will be described below, but the
dual damascene process is not limited thereto.
[0007] After forming a Cu layer on a substrate, an interlayer film,
such as a low dielectric film and an insulating film, is
accumulated as being multilayered thereon, and a photoresist
pattern is formed on the uppermost layer by a photolithography
technique. The photoresist pattern serves as a mask pattern for
forming via holes, in which openings are formed on regions where
via holes are to be formed. Thereafter, the multilayer structure
having the low dielectric film, the insulating film and the like is
etched by using the photoresist pattern as a mask to form via holes
reaching the Cu layer. The photoresist pattern is removed, and a
sacrifice layer containing an alkoxysilane material or the like is
charged in the via holes.
[0008] Subsequently, another photoresist pattern (mask pattern) for
forming a trench pattern is formed on the uppermost layer on the
remaining multilayer structure, and the low dielectric film, the
insulating film and the sacrifice layer are partially etched to a
prescribed depth with the pattern as a mask, whereby trenches for
wiring reaching the via holes are formed. The sacrifice layer
remaining in the via holes is then removed and cleaned. After
removing the photoresist pattern, Cu is charged in the via holes
and the trenches by plating process or the like, so as to form a
multilayer Cu wiring.
[0009] In the formation process by the dual damascene process, it
is necessary that not only the sacrifice layer is completely
removed and cleaned, but also damages on the low dielectric layer
having openings exposed to the dual damascene structure are
suppressed.
[0010] Upon removal of the sacrifice layer in the dual damascene
process, a buffered hydrofluoric acid and the like have been used
as a remover liquid (as shown, for example, U.S. Pat. No. 6,365,529
(column 8, lines 2 to 6) and U.S. Pat. No. 6,329,118 (column 7,
lines 57 to 61)), but in the case where the remover liquid is used,
there is such a problem that damages on the low dielectric layer
cannot be sufficiently suppressed.
[0011] The following remover liquids are proposed as a quaternary
ammonium remover liquid in the photolithography field, i.e., a
remover liquid containing a mixture of a quaternary ammonium salt,
dimethyl sulfoxide and water (in particular, a dimethyl sulfoxide
solution (containing 1.5 mass % of water) containing 0.5 mass % of
tetramethylammonium hydroxide) (as described in JP-A-8-301911
(paragraphs 0032 and 0043), a stripping composition containing a
polar aprotic solvent, such as dimethyl sulfoxide and sulfolane,
and an aggressive base, such as a quaternary ammonium hydroxide,
(as described in JP-A-2001-324823), and a remover liquid containing
dimethylsulfoxide, an alcohol amine, water and quaternary ammonium
hydroxide (as described in JP-A-7-28254). However, these are used
for removing an organic film, such as a photoresist, but there is
no disclosure on removal of a sacrifice layer and no suggestion on
suppression of damages on a low dielectric layer, in the dual
damascene process.
SUMMARY OF THE INVENTION
[0012] An object of the invention is to provide a cleaning liquid
attaining in a well balanced manner such effects that a sacrifice
layer used for forming a dual damascene structure is excellently
removed, and a low dielectric layer is not damaged upon formation
of a metallic wiring on a substrate having a metallic layer (such
as a Cu layer) and the low dielectric layer formed thereon.
[0013] The invention relates to, as one aspect, a cleaning liquid
used in a process for forming a dual damascene structure comprising
steps of etching a low dielectric layer accumulated on a substrate
having thereon a metallic layer to form a first etched-space;
charging a sacrifice layer in the first etched-space; partially
etching the low dielectric layer and the sacrifice layer to form a
second etched-space connected to the first etched-space; and
removing the sacrifice layer remaining in the first etched-space
with the cleaning liquid, wherein the cleaning liquid comprises (a)
1-25 mass % of a quaternary ammonium hydroxide represented by the
following general formula (I), (b) 30-70 mass % of a water soluble
organic solvent, and (c) 20-60 mass % of water:
##STR00001##
wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each independently
represents an alkyl group having 1-4 carbon atoms or a hydroxyalkyl
group having 1-4 carbon atoms.
[0014] The invention also relates to, as another aspect, a process
for treating a substrate having a dual-damascene structure
comprising steps of: etching a low dielectric layer accumulated on
a substrate having thereon a metallic layer to form a first
etched-space; charging a sacrifice layer in the first etched-space;
partially etching the low dielectric layer and the sacrifice layer
to form a second etched-space connected to the first etched-space;
and bringing the sacrifice layer remaining in the first
etched-space in contact with the aforementioned cleaning liquid to
remove the sacrifice layer.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The cleaning liquid of the invention is used for removing a
sacrifice layer in a process for forming a dual damascene structure
on a substrate having thereon a metallic layer and a low dielectric
layer, and component (a) is a quaternary ammonium hydroxide
represented by the following general formula (I):
##STR00002##
wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 each independently
represents an alkyl group having 1-4 carbon atoms or a hydroxyalkyl
group having 1-4 carbon atoms.
[0016] Specific examples thereof include tetramethylammonium
hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium
hydroxide, tetrabutylammonium hydroxide,
monomethyltripropylammonium hydroxide, trimethylethylammonium
hydroxide, (2-hydroxyethyl)trimethylammonium hydroxide [=choline],
(2-hydroxyethyl)triethylammonium hydroxide,
(2-hydroxyethyl)tripropylammonium hydroxide, and
(1-hydroxypropyl)trimethylammonium hydroxide. Among these, TMAH and
choline are preferred, and TMAH are most preferred, owing to the
high dissolving capability to a sacrifice layer. Component (a) may
be used singly or as a combination of two or more kinds
thereof.
[0017] The amount of component (a) in the cleaning liquid of the
invention is 1-25 mass %, and preferably 8-12 mass %. In the case
where the amount of component (a) is less than 1 mass %, the
dissolving capability to the sacrifice layer is low to fail to
attain sufficient removal thereof, and in the case where it exceeds
25 mass %, the low dielectric layer is damaged.
[0018] The water soluble organic solvent as component (b) may be
any organic solvent that is miscible with water and the other
components, and those having been conventionally used in this field
of art may be used. Specific examples thereof include a sulfoxide,
such as dimethyl sulfoxide; a sulfone, such as dimethyl sulfone,
diethyl sulfone, bis(2-hydroxyethyl)sulfone and tetramethyl
sulfone; an amide, such as N,N-dimethylformamide,
N-methylformamide, N,N-dimethylacetamide, N-methylacetamide and
N,N-diethylacetamide; a lactam, such as N-methyl-2-pyrrolidone,
N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone,
N-hydroxymethyl-2-pyrrolidone and N-hydroxyethyl-2-pyrrolidone; an
imidazolidinone, such as 1,3-dimethyl-2-imidazolidinone,
1,3-diethyl-2-imidazolidinone and
1,3-diisopropyl-2-imidazolidinone; and a polyhydric alcohol and a
derivative thereof, such as ethylene glycol, ethylene glycol
monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol
monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene
glycol monoethyl ether acetate, diethylene glycol, diethylene
glycol monomethyl ether, diethylene glycol monoethyl ether,
diethylene glycol monobutyl ether, propylene glycol monomethyl
ether, propylene glycol monoethyl ether, propylene glycol
monopropyl ether and propylene glycol monobutyl ether. Among these,
dimethyl sulfoxide and N-methyl-2-pyrrolidone are preferably used.
Component (b) may be used singly or as a combination of two or more
kinds thereof.
[0019] The amount of component (b) in the cleaning liquid of the
invention is 30-70 mass %, and preferably 40-60 mass %. In the case
where the amount of component (b) is less than 30 mass %, the low
dielectric layer is damaged, and in the case where it exceeds 70
mass %, the dissolving capability to the sacrifice layer is low to
fail to attain sufficient removal thereof.
[0020] The amount of water as component (c) in the cleaning liquid
of the invention is 20-60 mass %, and preferably 30-50 mass %. In
the case where the amount of component (c) is less than 20 mass %,
the dissolving capability to the sacrifice layer is low to fail to
attain sufficient removal thereof, and in the case where it exceeds
60 mass %, the low dielectric layer is damaged.
[0021] In addition to components (a) to (c), the cleaning liquid of
the invention may further contain (d) mercapto group-containing
compound, and/or (e) a quaternary ammonium hydroxide represented by
the following general formula (II), with the proviso that component
(e) differs from component (a):
##STR00003##
wherein R.sub.5, R.sub.6, R.sub.7 and R.sub.8 each independently
represents an alkyl group having 1-20 carbon atoms or a
hydroxyalkyl group having 1-20 carbon atoms, provided that at least
one of R.sub.5, R.sub.6, R.sub.7 and R.sub.8 represents an alkyl
group having 10 or more carbon atoms, or at least two of R.sub.5,
R.sub.6, R.sub.7 and R.sub.8 each independently represents a
hydroxyalkyl group having 2-5 carbon atoms.
[0022] As component (d), a compound is preferred which has a
structure that has a hydroxyl group and/or a carboxyl group on at
least one of an .alpha.-position and a .beta.-position of a carbon
atom connected to a mercapto group. Specific preferred examples of
the compound include 1-thioglycerol,
3-(2-aminophenylthio)-2-hydroxypropylmercaptan,
3-(2-hydroxyethylthio)-2-hydroxypropylmercaptan,
2-mercaptopropionic acid and 3-mercaptopropionic acid. Among these,
1-thioglycerol is particularly preferably used. Component (d) may
be used singly or as a combination of two or more kinds
thereof.
[0023] In the incorporation of component (d), the amount thereof in
the cleaning liquid of the invention is preferably 0.01-15 mass %,
and particularly 0.1-10 mass %. Corrosion of Cu can be further
effectively prevented by the incorporation of component (d).
[0024] Specific preferred examples of component (e) include
hexadecyltrimethylammonium hydroxide,
tri(2-hydroxyethyl)methylammonium hydroxide and
tetra(2-hydroxyethyl)ammonium hydroxide. Component (e) may be used
singly or as a combination of two or more kinds thereof.
[0025] In the incorporation of component (e), the amount thereof in
the cleaning liquid of the invention is preferably 0.01-15 mass %,
and particularly 0.1-10 mass %. Corrosion of Cu can be further
effectively prevented by the incorporation of component (e).
[0026] Examples of a specific embodiment of the use of the cleaning
liquid according to the invention and a specific embodiment of a
process for treating a substrate using the cleaning liquid
according to the invention will be described below. However, the
invention is not limited to the examples.
[0027] As the dual damascene process used in the invention,
processes having been known in this field of art may be employed,
which include the via first process, in which via holes are firstly
formed, and then trenches (trenches for wiring) are formed, and the
trench first process, in which trenches are firstly formed, and
then via holes are formed.
[0028] Specifically, for example, a metallic layer (an
electroconductive layer) is provided on a substrate, a barrier
layer (an etching stopper layer) is then provided thereon. A low
dielectric layer is accumulated on the barrier layer, and a
photoresist layer is provided on the low dielectric layer. The
photoresist layer is then selectively exposed and developed to form
a photoresist pattern.
[0029] Subsequently, in the via first process, the low dielectric
layer is etched by using the photoresist pattern as a mask to form
via holes (i.e., the first etched-space) connected to the metallic
layer on the substrate, and the photoresist pattern is then removed
by ashing treatment or the like. A sacrifice layer is then charged
in the via holes. Thereafter, another photoresist pattern is formed
on the remaining low dielectric layer, and the low dielectric layer
and the sacrifice layer are etched to a prescribed depth by using
the photoresist pattern as a mask to form trenches (i.e., the
second etched-space) connected to the via holes.
[0030] In the trench first process, on the other hand, the low
dielectric layer is etched to a prescribed thickness by using the
photoresist pattern as a mask to form trenches (i.e., the first
etched-space), and the photoresist pattern is then removed by
ashing treatment or the like. A sacrifice layer is then charged in
the trenches. Thereafter, another photoresist pattern is formed on
the remaining low dielectric layer, and the low dielectric layer
and the sacrifice layer are etched to connect to the trench by
using the photoresist pattern as a mask to form via holes (i.e.,
the second etched-space), lower parts of which are connected to the
Cu layer on the substrate.
[0031] After completing one of the foregoing processes, the
sacrifice layer charged in the via holes in the via first process,
or the sacrifice layer charged in the trenches in the trench first
process is made in contact with the cleaning liquid according to
the invention to remove the sacrifice layer. A metal is charged in
the via holes and the trenches of the substrate thus processed to
produce a multilayer metallic wiring substrate.
[0032] Examples of the material for the metallic layer include Cu,
a Cu alloy, Al and an Al alloy. The metallic layer may be formed by
the CVD vapor deposition process, the electrolytic plating or the
like, but is not limited thereto.
[0033] Examples of the material for the barrier (etching stopper)
layer include SiN, SiCN, Ta and TaN.
[0034] Examples of the material for the low dielectric layer
include a low dielectric material (low-k material), for example, a
carbon-doped silicon oxide (SiOC) material, such as "Black Diamond"
(produced by Applied Materials, Inc.), "Coral" (produced by
Novellus Systems, Inc.) and "Aurora" (produced by ASM Japan Co.,
Ltd.); an MSQ (methylsilsesquioxane) material, such as "OCD T-7",
"OCD T-9", "OCD T-11", "OCD T-31" and "OCD T-39" (all produced by
Tokyo Ohka Kogyo Co., Ltd.); and an HSQ (hydroxysilsesquioxane)
material, such as "OCD T-12" and "OCD T-32" (all produced by Tokyo
Ohka Kogyo Co., Ltd.), but it is not limited to these examples.
[0035] The low dielectric layer may be formed directly on the
metallic layer. The formation of the low dielectric layer can be
carried out by coating the low dielectric material (low-k material)
as exemplified above and baked, in general, at a high temperature
of 350.degree. C. or higher to attain crystallization.
[0036] Preferred examples of the photoresist include photoresist
materials having been generally used for a KrF, ArF or F.sub.2
excimer laser or an electron beam. The photoresist pattern may be
formed by the ordinary photolithography technique.
[0037] The etching of the low dielectric layer may be carried out
by the ordinary process, such as dry etching. The ashing of the
photoresist pattern may also be carried out by the ordinary
process. In the case where the low dielectric layer has a low
dielectric constant (k) of about 3 or less, the ashing is not
carried out due to the low ashing resistance thereof, but the
photoresist pattern can be removed with a known resist remover
liquid or the like.
[0038] Subsequently, the sacrifice layer is charged in the first
etched-space (i.e., the via holes or the trenches) thus formed. As
the material for the sacrifice layer, for example, a spin-on-glass
material or a material obtained by adding a light absorbing
substance thereto is employed.
[0039] Examples of the spin-on-glass material include a material
obtained by hydrolyzing at least one compound selected from the
following compounds (i) to (iii) in the presence of an acid
catalyst, but it is not limited thereto.
[0040] The compound (i) is represented by the following general
formula (III):
Si(OR.sub.9).sub.a(OR.sub.10).sub.b(OR.sub.11).sub.c(OR.sub.12).sub.d
(III)
wherein R.sub.9, R.sub.10, R.sub.11 and R.sub.12 each independently
represents an alkyl group having 1-4 carbon atoms or a phenyl
group; and a, b, c and d each independently represents an integer
of 0-4, provided that a, b, c and d satisfy a condition of
a+b+c+d=4.
[0041] The compound (II) is represented by the following general
formula (IV):
R.sub.13Si(OR.sub.14).sub.e(OR.sub.15).sub.f(OR.sub.16).sub.g
(IV)
wherein R.sub.13 represents a hydrogen atom, an alkyl group having
1-4 carbon atoms or a phenyl group; R.sub.14, R.sub.15 and R.sub.16
each independently represents an alkyl group having 1-4 carbon
atoms or a phenyl group; and e, f and g each independently
represents an integer of 0-3, provided that e, f and g satisfy a
condition of e+f+g=3.
[0042] The compound (iii) is represented by the following general
formula (V):
R.sub.17R.sub.18Si(OR.sub.19).sub.h(OR.sub.20).sub.i (V)
wherein R.sub.17 and R.sub.18 each independently represents a
hydrogen atom, an alkyl group having 1-4 carbon atoms or a phenyl
group; R.sub.19 and R.sub.20 each independently represents an alkyl
group having 1-4 carbon atoms or a phenyl group; and h and i each
independently represents an integer of 0-2, provided that h and i
satisfy a condition of h+i=2.
[0043] Examples of the compound (i) include tetramethoxysilane,
tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane,
tetraphenoxysilane, trimethoxymonoethoxysilane,
dimethoxydiethoxysilane, triethoxymonomethoxysilane,
trimethoxymonopropoxysilane, monomethoxytributoxysilane,
monomethoxytriphenoxysilane, dimethoxydipropoxysilane,
tripropoxymonomethoxysilane, trimethoxymonobutoxysilane,
dimethoxydibutoxysilane, triethoxymonopropoxysilane,
diethoxydipropoxysilane, tributoxymonopropoxysilane,
dimethoxymonoethoxymonobutoxysilane,
diethoxymonomethoxymonobutoxysilane,
diethoxymonopropoxymonobutoxysilane,
dipropoxymonomethoxymonoethoxysilane,
dipropoxymonomethoxymonobutoxysilane,
dipropoxymonoethoxymonobutoxysilane,
dibutoxymonomethoxymonoethoxysilane,
dibutoxymonoethoxymonopropoxysilane and
monomethoxymonoethoxymonopropoxymonobutoxysilane.
[0044] Examples of the compound (II) include trimethoxysilane,
triethoxysilane, tripropoxysilane, triphenoxysilane,
dimethoxymonoethoxysilane, diethoxymonomethoxysilane,
dipropoxymonomethoxysilane, dipropoxymonoethoxysilane,
diphenoxymonomethoxysilane, diphenoxymonoethoxysilane,
diphenoxymonopropoxysilane, methoxyethoxypropoxysilane,
monopropoxydimethoxysilane, monopropoxydiethoxysilane,
monobutoxydimethoxysilane, monophenoxydiethoxysilane,
methyltrimethoxysilane, methyltriethoxysilane,
methyltripropoxysilane, ethyltrimethoxysilane,
ethyltripropoxysilane, ethyltriphenoxysilane,
propyltrimethoxysilane, propyltriethoxysilane,
propyltriphenoxysilane, butyltrimethoxysilane,
butyltriethoxysilane, butyltripropoxysilane, butyltriphenoxysilane,
methylmonomethoxydiethoxysilane, ethylmonomethoxydiethoxysilane,
propylmonomethoxydiethoxysilane, butylmonomethoxydiethoxysilane,
methylmonomethoxydipropoxysilane, methylmonomethoxydiphenoxysilane,
ethylmonomethoxydipropoxysilane, ethylmonomethoxydiphenoxysilane,
propylmonomethoxydipropoxysilane, propylmonomethoxydiphenoxysilane,
butylmonomethoxydipropoxysilane, butylmonomethoxydiphenoxysilane,
methylmethoxyethoxypropoxysilane, propylmethoxyethoxypropoxysilane,
butylmethoxyethoxypropoxysilane,
methylmonomethoxymonoethoxymonobutoxysilane,
ethylmonomethoxymonoethoxymonobutoxysilane,
propylmonomethoxymonoethoxymonobutoxysilane and
butylmonomethoxymonoethoxymonobutoxysilane.
[0045] Examples of the compound (iii) include dimethoxysilane,
diethoxysilane, dipropoxysilane, diphenoxysilane,
methoxyethoxysilane, methoxypropoxysilane, methoxyphenoxysilane,
ethoxypropoxysilane, ethoxyphenoxysilane, methyldimethoxysilane,
methylmethoxyethoxysilane, methyldiethoxysilane,
methylmethoxypropoxysilane, methylmethoxyphenoxysilane,
ethyldipropoxysilane, ethylmethoxypropoxysilane,
ethyldiphenoxysilane, propyldimethoxysilane,
propylmethoxyethoxysilane, propylethoxypropoxysilane,
propyldiethoxysilane, propyldiphenoxysilane, butyldimethoxysilane,
butylmethoxyethoxysilane, butyldiethoxysilane,
butylethoxypropoxysilane, butyldipropoxysilane,
butylmethylphenoxysilane, dimethyldimethoxysilane,
dimethylmethoxyethoxysilane, dimethyldiethoxysilane,
dimethyldiphenoxysilane, dimethylethoxypropoxysilane,
dimethyldipropoxysilane, diethylmethoxysilane,
diethylmethoxypropoxysilane, diethyldiethoxysilane,
diethylethoxypropoxysilane, dipropyldimethoxysilane,
dipropyldiethoxysilane, dipropyldiphenoxysilane,
dibutyldimethoxysilane, dibutyldiethoxysilane,
dibutyldipropoxysilane, dibutylmethoxy, phenoxysilane,
methylethyldimethoxysilane, methylethyldiethoxysilane,
methylethyldipropoxysilane, methylethyldiphenoxysilane,
methylpropyldimethoxysilane, methylpropyldiethoxysilane,
methylbutyldimethyoxysilane, methylbutyldiethoxysilane,
methylbutyldipropoxysilane, methylethylethoxypropoxysilane,
ethylpropyldimethoxysilane, ethylpropylmethoxyethoxysilane,
dipropyldimethoxysilane, dipropylmethoxyethoxysilane,
propylbutyldimethoxysilane, propylbutyldiethoxysilane,
dibutylmethoxyethoxysilane, dibutylmethoxypropoxysilane and
dibutylethoxypropoxysilane.
[0046] Preferred examples of the light absorbing substance that can
be added to the spin-on-glass material include at least one kind of
a compound having, in the structure thereof, a substituent capable
of being condensed with the compounds (i) to (iii). Examples of the
light absorbing substance include a sulfone compound, a
benzophenone compound, an anthracene compound and a naphthalene
compound. In particular, a bisphenylsulfone compound and a
benzophenone compound having at least two hydroxyl groups, an
anthracene compound having at least one substituent selected from a
hydroxyl group, a hydroxyalkyl group and a carboxyl group, and a
naphthalene compound having at least one substituent selected from
a hydroxyl group and a carboxyl group are preferred.
[0047] Examples of the bisphenylsulfone compound having at least
two hydroxyl groups include a bis(hydroxyphenyl)sulfone compound
and a bis(polyhydroxyphenyl)sulfone compound. Specific examples
thereof include bis(4-hydroxyphenyl)sulfone,
bis(3,5-dimethyl-4-hydroxyphenyl)sulfone,
bis(2,3-dihydroxyphenyl)sulfone, bis(2,4-dihydroxyphenyl)sulfone,
bis(2,4-dihydroxy-6-methylphenyl)sulfone,
bis(5-chloro-2,4-dihydroxyphenyl)sulfone,
bis(2,5-dihydroxyphenyl)sulfone, bis(3,4-dihydroxyphenyl)sulfone,
bis(3,5-dihydroxyphenyl)sulfone,
bis(2,3,4-trihydroxyphenyl)sulfone,
bis(2,3,4-trihydroxy-6-methylphenyl)sulfone,
bis(5-chloro-2,3,4-trihydroxyphenyl)sulfone,
bis(2,4,6-trihydroxyphenyl)sulfone and
bis(5-chloro-2,3-dihydroxyphenyl)sulfone.
[0048] Examples of the benzophenone compound having at least two
hydroxyl groups include 2,4-dihydroxybenzophenone,
2,3,4-trihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone,
2,2',5,6'-tetrahydroxybenzophenone,
2,2'-dihydroxy-4-methoxybenzophenone,
2,6-dihydroxy-4-methoxybenzophenone,
2,2'-dihydroxy-4,4'-dimethoxybenzophenone,
4-dimethylamino-2',4,4'-dihydroxybenzophenone and
4-dimethylamino-3',4'-dihydroxybenzophenone.
[0049] Examples of the anthracene compound having at least one
substituent selected from a hydroxyl group, a hydroxyalkyl group
and a carboxyl group include a compound represented by the
following general formula (VI):
##STR00004##
wherein p represents an integer of 0-8; q represents an integer of
0-10; r represents an integer of 0-6; and s represents 0 or 1,
provided that p, q and r are not simultaneously 0.
[0050] Specific examples of the compound include
1-hydroxyanthracene, 9-hydroxyanthracene, anthracene-9-carboxylic
acid, 1,2-dihydroxyanthracene, 1,2-dihydroxy-9-carboxyanthracene,
1,5-dihydroxyanthracene, 1,5-dihydroxy-9-carboxyanthracene,
9,10-dihydroxyanthracene, 1,2,3-trihydroxyanthracene,
1,2,3,4-tetrahydroxyanthracene, 1,2,3,4,5,6-hexahydroxyanthracene,
1,2,3,4,5,6,7,8-octahydroxyanthracene, 1-hydroxymethylanthracene,
9-hydroxymethylanthracene, 9-hydroxyethylanthracene,
9-hydroxyhexylanthracene, 9-hydroxyoctylanthracene and
9,10-dihydroxymethylanthracene.
[0051] Specific examples of the naphthalene compound having at
least one substituent selected from a hydroxyl group and a carboxyl
group include 1-naphthol, 2-naphthol, 1-naphthalene ethanol,
2-naphthalene ethanol, 1,3-naphthalenediol,
naphthalene-1-carboxylic acid, naphthalene-2-carboxylic acid,
naphthalene-1,4-dicarboxylic acid, naphthalene-2,3-dicarboxylic
acid, naphthalene-2,6-dicarboxylic acid,
naphthalene-2,7-dicarboxylic acid and naphthalene-1-acetic
acid.
[0052] The spin-on-glass material is charged in the first
etched-space (i.e., the via holes or the trenches) and then baked
at a relatively low temperature of 250.degree. C. or lower to form
the sacrifice layer.
[0053] The spin-on-glass material as the material for the sacrifice
layer preferably has an etching rate equivalent to that of the
material used in the low dielectric layer, and a material of the
same kind as the low dielectric layer may be used therefor.
However, while the low dielectric layer is formed through
crystallization by baking at a high temperature, the sacrifice
layer is formed by baking at a relatively lower temperature than
the crystallization temperature since it is finally removed after
etching.
[0054] Subsequently, another resist pattern is formed on the low
dielectric layer, and the second etched-space (i.e., the trenches
or the via holes) is formed by using the photoresist pattern as a
mask according to an ordinary process. Consequently, a dual
damascene structure is formed, which is an interconnection
structure connected to the metallic layer on the substrate.
[0055] It is necessary herein that the sacrifice layer remaining in
the first etched-space is removed. The sacrifice layer can be
completely removed by bringing it in contact with the cleaning
liquid according to the invention without damaging the part of the
low dielectric layer that is exposed to the etched-space.
[0056] The contact to the cleaning liquid may be carried out by an
ordinary method, such as a dipping method, a paddle method and a
shower method. The contact time may be a period of time sufficient
to remove the sacrifice layer and can be appropriately adjusted
depending on the contact method. The contact is generally carried
out at a temperature of 20-80.degree. C. for 1-40 minutes, but the
invention is not limited thereto.
[0057] The photoresist pattern on the low dielectric layer is then
removed by ashing treatment or the like. As described in the
foregoing, in the case where the low dielectric layer has a low
dielectric constant (k) of about 3 or less, the ashing is not
carried out due to the low ashing resistance thereof, but the
photoresist pattern can be removed with a known resist remover
liquid or the like.
[0058] The cleaning liquid of the invention exhibits a large
difference between the solubility to the low dielectric layer
(low-k layer) and the solubility to the sacrifice layer, and
therefore, it readily provides a good selectivity. Furthermore,
damages on the low dielectric layer (low-k layer) can be
considerably decreased in comparison to the case using a diluted
hydrofluoric acid solution, which has been often used as a remover
for a sacrifice layer.
EXAMPLE
[0059] The invention will be described in detail below with
reference to the example, but the invention is not construed as
being limited thereto. All the amounts in the example are in terms
of percent by mass unless otherwise indicated.
Examples 1-5 and Comparative Examples 1-5
[0060] A barrier layer formed with an SiN film as the first layer,
a low dielectric layer (formed with "OCD T-12", produced by Tokyo
Ohka Kogyo Co., Ltd.) as the second layer, a barrier layer formed
with an SiN film as the third layer, and a low dielectric layer
(formed with "OCD T-12", produced by Tokyo Ohka Kogyo Co., Ltd.) as
the fourth layer were formed on a substrate having a Cu layer
formed thereon. A photoresist pattern is formed thereon by the
photolithography technique, and via holes connected to the Cu layer
were formed by etching the first to fourth layers with the
photoresist patter as a mask. A sacrifice layer (formed with "OCD
T-32", produced by Tokyo Ohka Kogyo Co., Ltd.) was charged in the
via holes (baked at 200.degree. C.). Another photoresist pattern is
formed thereon by the photolithography technique, and trenches were
formed by etching with the photoresist pattern as a mask.
[0061] The substrate thus obtained was subjected to a dipping
treatment in the cleaning liquids shown in Table 1 below (at
40.degree. C. for 20 minutes), and then rinsed with pure water. The
removing capability to the sacrifice layer (dissolving capability)
and the state of damages (corrosion) of the low dielectric layer
were evaluated by observing with an SEM (scanning electron
microscope). The results obtained are shown in Table 2 below.
[0062] The removing capability to the sacrifice layer (dissolving
capability) and the state of damages (corrosion) of the low
dielectric layer were evaluated with the following standards.
<Removing capability to Sacrifice Layer (Dissolving
Capability> S: The sacrifice layer was completely removed (i.e.,
no residue remaining in the via holes was found). A: A slight
amount of a residue remained.
<State of Corrosion of Low Dielectric Layer>
[0063] S: No corrosion was found. A: Slight corrosion (roughness)
was found on the surface of the low dielectric layer. B: Corrosion
of the surface of the low dielectric layer was found.
TABLE-US-00001 TABLE 1 Components of cleaning liquid (amount (mass
%)) Component Component Component Component Component Other (a) (b)
(c) (d) (e) component Example 1 TMAH DMSO (40) -- -- -- (10) (50)
Example 2 Choline DMSO (40) -- -- -- (10) (50) Example 3 TMAH (5),
DMSO (40) -- -- -- Choline (5) (50) Example 4 Choline DMSO (40)
1-thioglycerol -- -- (10) (49.5) (0.5) Example 5 TMAH DMSO (40) --
HDTMAH -- (10) (49.5) (0.5) Comparative 0.1 mass % buffered
hydrofluoric acid aqueous solution (100) Example 1 Comparative TMAH
DMSO (35) -- -- -- Example 2 (30) (35) Comparative TMAH DMSO (39.5)
-- -- -- Example 3 (0.5) (60) Comparative TMAH DMSO (70) -- -- --
Example 4 (10) (20) Comparative TMAH DMSO (15) -- -- -- Example 5
(5) (80) Note: Components shown in Table 1 are as follows. TMAH:
tetramethylammonium hydroxide Choline:
(2-hydroxyethyl)trimethylammonium hydroxide DMSO: dimethyl
sulfoxide HDTMAH: hexadecyltrimethylammonium hydroxide
TABLE-US-00002 TABLE 2 Removing State of capability to corrosion of
low sacrifice layer dielectric layer Example 1 S S Example 2 S S
Example 3 S S Example 4 S S Example 5 S S Comparative Example 1 S B
Comparative Example 2 S B Comparative Example 3 A S Comparative
Example 4 S B Comparative Example 5 A S
[0064] As described in detail above, according to the invention, a
cleaning liquid can be obtained that attains in a well balanced
manner such effects that a sacrifice layer used for forming a dual
damascene structure is excellently removed, and a low dielectric
layer is not damaged upon formation of a metallic wiring on a
substrate having a metallic layer and the low dielectric layer
formed thereon.
* * * * *