U.S. patent application number 16/251458 was filed with the patent office on 2019-05-23 for pattern-forming method and composition for resist pattern-refinement.
This patent application is currently assigned to JSR CORPORATION. The applicant listed for this patent is JSR CORPORATION. Invention is credited to Yusuke ANNO, Ken MARUYAMA, Kanako MEYA, Shuto MORI.
Application Number | 20190155162 16/251458 |
Document ID | / |
Family ID | 57015850 |
Filed Date | 2019-05-23 |
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United States Patent
Application |
20190155162 |
Kind Code |
A1 |
MEYA; Kanako ; et
al. |
May 23, 2019 |
PATTERN-FORMING METHOD AND COMPOSITION FOR RESIST
PATTERN-REFINEMENT
Abstract
A pattern-forming method comprises forming a prepattern that is
insoluble or hardly soluble in an organic solvent. A first
composition is applied on at least lateral faces of the prepattern
to fort i a resin layer. Adjacent regions to the prepattern of the
resin layer are insolubilized or desolubilized in the organic
solvent without being accompanied by an increase in a molecular
weight by heating the prepattern and the resin layer. Regions other
than the adjacent regions insolubilized or desolubilized of the
resin layer are removed with the organic solvent. The first
composition comprises a first polymer having a solubility in the
organic solvent to be decreased by an action of an acid. At least
one selected from the following features (i) and (ii) is satisfied:
(i) the first polymer comprises a basic group; and (ii) the first
composition further comprises a basic compound.
Inventors: |
MEYA; Kanako; (Tokyo,
JP) ; ANNO; Yusuke; (Tokyo, JP) ; MARUYAMA;
Ken; (Tokyo, JP) ; MORI; Shuto; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JSR CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
JSR CORPORATION
Tokyo
JP
|
Family ID: |
57015850 |
Appl. No.: |
16/251458 |
Filed: |
January 18, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15082389 |
Mar 28, 2016 |
10216090 |
|
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16251458 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03F 7/0397 20130101;
G03F 7/40 20130101; H01L 21/0273 20130101; G03F 7/405 20130101;
G03F 7/325 20130101 |
International
Class: |
G03F 7/40 20060101
G03F007/40; G03F 7/039 20060101 G03F007/039; H01L 21/027 20060101
H01L021/027; G03F 7/32 20060101 G03F007/32 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2015 |
JP |
2015-074644 |
Mar 9, 2016 |
JP |
2016-046167 |
Claims
1. A resist pattern-refinement composition, comprising a polymer
comprising a basic group and having a solubility in an organic
solvent to be decreased by an action of an acid.
2. The resist pattern-refinement composition according to claim 1,
wherein the polymer comprises a structural unit comprising an
aromatic ring, and a proportion of the structural unit with respect
to total structural units in the polymer is no less than 20 mol
%.
3. The resist pattern-refinement composition according to claim 1,
wherein the polymer has a weight average molecular weight of no
less than 13,000 and no greater than 150,000.
4. A resist pattern-refinement composition, comprising a polymer
having a solubility in an organic solvent to be decreased by an
action of an acid; and a basic compound.
5. The resist pattern-refinement composition according to claim 4,
wherein the polymer comprises a structural unit comprising an
aromatic ring, and a proportion of the structural unit with respect
to total structural units in the polymer is no less than 20 mol
%.
6. The resist pattern-refinement composition according to claim 4,
wherein the polymer has a weight average molecular weight of no
less than 13,000 and no greater than 150,000.
7. A resist pattern-refinement composition, comprising a basic
compound and an organic solvent, and not comprising a polymer
having a solubility in an organic solvent to be decreased by an
action of an acid.
8. The resist pattern-refinement composition according to claim 1,
wherein the polymer further comprises an acid-labile group.
9. The resist pattern-refinement composition according to claim 1,
wherein the basic group is a group represented by formula (a), a
group represented by formula (b) or a combination thereof,
##STR00027## wherein, in the formula (b), L represents a single
bond, a divalent chain hydrocarbon group having 1 to 20 carbon
atoms or a divalent alicyclic hydrocarbon group having 3 to 20
carbon atoms; and R.sup.A and R.sup.B each independently represent
a hydrogen atom, a monovalent chain hydrocarbon group having 1 to
20 carbon atoms or a monovalent alicyclic hydrocarbon group having
3 to 20 carbon atoms, or L and R.sup.A optionally taken together
represent an aliphatic heterocyclic structure having 3 to 20 ring
atoms together with the nitrogen atom to which L and R.sup.A
bond.
10. The resist pattern-refinement composition according to claim 1,
wherein the composition further comprises an acid incrementor.
11. The resist pattern-refinement composition according to claim 1,
wherein the polymer further comprises a hydroxy group, a carboxy
group, an oxo group, a group comprising a lactone structure, a
group comprising a cyclic carbonate structure, a group comprising a
sultone structure, or a combination thereof.
12. The resist pattern-refinement composition according to claim 1,
wherein the polymer further comprises: an acid-labile group; and a
hydroxy group, a carboxy group, an oxo group, a group comprising a
lactone structure, a group comprising a cyclic carbonate structure,
a group comprising a sultone structure, or a combination thereof,
and wherein the basic group is a group represented by formula (a),
a group represented by formula (b) or a combination thereof,
##STR00028## wherein, in the formula (b), L represents a single
bond, a divalent chain hydrocarbon group having 1 to 20 carbon
atoms or a divalent alicyclic hydrocarbon group having 3 to 20
carbon atoms; and R.sup.A and R.sup.B each independently represent
a hydrogen atom, a monovalent chain hydrocarbon group having 1 to
20 carbon atoms or a monovalent alicyclic hydrocarbon group having
3 to 20 carbon atoms, or L and R.sup.A optionally taken together
represent an aliphatic heterocyclic structure having 3 to 20 ring
atoms together with the nitrogen atom to which L and R.sup.A
bond.
13. The resist pattern-refinement composition according to claim 4,
wherein the polymer comprises an acid-labile group.
14. The resist pattern-refinement composition according to claim 4,
wherein the basic compound is represented by formula (X), a
compound represented by formula (Y) or a combination thereof,
##STR00029## wherein, in the formula (X), X.sup.+ represents a
monovalent onium cation; and Y.sup.- represents a monovalent
carboxylate anion or a monovalent sulfonamide anion, and in the
formula (Y), R.sup.X, R.sup.Y and R.sup.Z each independently
represent an unsubstituted, hydroxy-substituted or
amino-substituted monovalent chain hydrocarbon group having 1 to 20
carbon atoms or an unsubstituted, hydroxy-substituted or
amino-substituted monovalent alicyclic hydrocarbon group having 3
to 20 carbon atoms, or at least two of R.sup.X, R.sup.Y and R.sup.Z
taken together represent an aliphatic heterocyclic structure having
3 to 20 ring atoms together with the nitrogen atom to which the at
least two of R.sup.X, R.sup.Y and R.sup.Z bond and the rest of
R.sup.X, R.sup.Y and R.sup.Z represents an unsubstituted,
hydroxy-substituted or amino-substituted monovalent chain
hydrocarbon group having 1 to 20 carbon atoms or an unsubstituted,
hydroxy-substituted substituted or amino-substituted monovalent
alicyclic hydrocarbon group having 3 to 20 carbon atoms.
15. The resist pattern-refinement composition according to claim 4,
wherein the composition further comprises an acid incrementor.
16. The resist pattern-refinement composition according to claim 4,
wherein the polymer comprises a hydroxy group, a carboxy group, an
oxo group, a group comprising a lactone structure, a group
comprising a cyclic carbonate structure, a group comprising a
sultone structure, or a combination thereof.
17. The resist pattern-refinement composition according to claim 4,
wherein the polymer comprises: an acid-labile group; and a hydroxy
group, a carboxy group, an oxo group, a group comprising a lactone
structure, a group comprising a cyclic carbonate structure, a group
comprising a sultone structure, or a combination thereof, and
wherein the basic compound is represented by formula (X), a
compound represented by formula (Y) or a combination thereof,
##STR00030## wherein, in the formula (X), X.sup.+ represents a
monovalent onium cation; and Y.sup.- represents a monovalent
carboxylate anion or a monovalent sulfonamide anion, and in the
formula (Y), R.sup.X, R.sup.Y and R.sup.Z each independently
represent an unsubstituted, hydroxy-substituted or
amino-substituted monovalent chain hydrocarbon group having 1 to 20
carbon atoms or an unsubstituted, hydroxy-substituted or
amino-substituted monovalent alicyclic hydrocarbon group having 3
to 20 carbon atoms, or at least two of R.sup.X, R.sup.Y and R.sup.Z
taken together represent an aliphatic heterocyclic structure having
3 to 20 ring atoms together with the nitrogen atom to which the at
least two of R.sup.X, R.sup.Y and R.sup.Z bond and the rest of
R.sup.X, R.sup.Y and R.sup.Z represents an unsubstituted,
hydroxy-substituted or amino-substituted monovalent chain
hydrocarbon group having 1 to 20 carbon atoms or an unsubstituted,
hydroxy-substituted or amino-substituted monovalent alicyclic
hydrocarbon group having 3 to 20 carbon atoms.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional application of U.S.
patent application Ser. No. 15/082,389 filed Mar. 28, 2016, which
claims priority to Japanese Patent Application No. 2015-074644,
filed Mar. 31, 2015, and to Japanese Patent Application No.
2016-046167, filed Mar. 9, 2016. The contents of these applications
are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates to a pattern-forming method
and a composition for resist pattern-refinement.
Discussion of the Background
[0003] Miniaturization of structures of various types of electronic
devices such as semiconductor devices and liquid crystal devices
has been accompanied by demands for microfabrication of patterns in
lithography processes. To address such demands, a method of forming
a pattern by exposing and developing a resist film formed using a
resist composition containing a radiation-sensitive acid generator
and a polymer having a solubility in a developer solution that will
be altered by the action of an acid, and additionally a method in
which further refining is attempted based on the pattern thus
formed have been studied.
[0004] Such a method is exemplified by a known technique which
includes subjecting a formed pattern (prepattern) to an action of a
crosslinking layer-forming material, thereby permitting
crosslinkage of the crosslinking layer-forming material with a
resin constituting the pattern to form a crosslinking layer (see
Japanese Unexamined Patent Application, Publication No.
2008-310314). Further, a technique which includes: applying a
coating-forming agent on a resist pattern; then heating to form a
layer that is hardly soluble in a developer solution without being
accompanied by an increase in the molecular weight on the surface
of the resist pattern, so as to increase the thickness of the
pattern has been studied (see Japanese Unexamined Patent
Application, Publication No. 2013-117710). Furthermore, a technique
of increasing the thickness of a pattern by forming a film on a
negative pattern using a composition containing a compound having a
solubility in a removing liquid containing an organic solvent that
will be increased by the action of an acid through an increase in
the polarity has been studied (see Japanese Unexamined Patent
Application, Publication No. 2013-257435).
SUMMARY OF THE INVENTION
[0005] According to one aspect of the present invention, a
pattern-forming method comprises forming a prepattern that is
insoluble or hardly soluble in an organic solvent. A first
composition is applied on at least lateral faces of the prepattern
to form a resin layer. Adjacent regions to the prepattern of the
resin layer are insolubilized or desolubilized in the organic
solvent without being accompanied by an increase in a molecular
weight by heating the prepattern and the resin layer. Regions other
than the adjacent regions insolubilized or desolubilized of the
resin layer are removed with the organic solvent. The first
composition comprises a first polymer having a solubility in the
organic solvent to be decreased by an action of an acid. At least
one selected from the following features (i) and (ii) is satisfied:
(i) the first polymer comprises a basic group; and (ii) the first
composition further comprises a basic compound.
[0006] According to another aspect of the present invention, a
pattern-forming method comprises forming a prepattern that is
insoluble or hardly soluble in an organic solvent. At least lateral
faces of the prepattern are brought into contact with a composition
which comprises a basic compound and an organic solvent and which
does not comprise a polymer having a solubility in an organic
solvent to be decreased by an action of an acid. A composition is
applied on at least lateral faces of the prepattern to form a resin
layer. The composition comprises a polymer having a solubility in
the organic solvent to be decreased by an action of an acid. The
polymer has a weight average molecular weight of no less than
13,000 and no greater than 150,000. Adjacent regions to the
prepattern of the resin layer are insolubilized or desolubilized in
the organic solvent without being accompanied by an increase in a
molecular weight by heating the prepattern and the resin layer.
Regions other than the adjacent regions insolubilized or
desolubilized of the resin layer are removed with the organic
solvent.
[0007] According further aspect of the present invention, a resist
pattern-refinement composition comprises a polymer having a
solubility in an organic solvent to be decreased by an action of an
acid.
[0008] According further aspect of the present invention, a resist
pattern-refinement composition comprises a polymer having a
solubility in an organic solvent to be decreased by an action of an
acid; and a basic compound.
[0009] According further aspect of the present invention, a resist
pattern-refinement composition comprises a basic compound and an
organic solvent, and not comprises a polymer having a solubility in
an organic solvent to be decreased by an action of an acid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIGS. 1A to 1D show a schematic view illustrating one
embodiment of the pattern-forming method of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] According to an embodiment of the invention made for solving
the aforementioned problems, a pattern-forming method includes the
steps of: forming a prepattern that is insoluble or hardly soluble
in an organic solvent (hereinafter, may be also referred to as
"prepattern-forming step"); forming a resin layer on at least
lateral faces of the prepattern (hereinafter, may be also referred
to as "resin layer-forming step"); insolubilizing or desolubilizing
in the organic solvent, adjacent regions to the prepattern of the
resin layer without being accompanied by an increase in the
molecular weight by heating the prepattern and the resin layer
(hereinafter, may be also referred to as "insolubilizing or
desolubilizing step"); and removing regions other than the adjacent
regions insolubilized or desolubilized of the resin layer with the
organic solvent (hereinafter, may be also referred to as "removing
step"), wherein the resin layer is formed from a first composition
(hereinafter, may be also referred to as "composition (I)") which
contains a first polymer (hereinafter, may be also referred to as
"polymer (I)") having a solubility in the organic solvent to be
decreased by an action of an acid, and which involves at least one
selected from the following features (i) and (ii):
[0012] (i) the first polymer having a basic group; and
[0013] (ii) the first composition further containing a basic
compound.
[0014] In addition, according to another embodiment of the
invention, a pattern-forming method (hereinafter, may be also
referred to as "pattern-forming method (a)") includes the steps of:
forming a prepattern that is insoluble or hardly soluble in an
organic solvent; forming a prepattern that is insoluble or hardly
soluble in the organic solvent; bringing into contact with at least
lateral faces of the prepattern, a composition which contains a
basic compound and an organic solvent and which does not contain a
polymer having a solubility in the organic solvent to be decreased
by an action of an acid; forming a resin layer on at least lateral
faces of the prepattern; insolubilizing or desolubilizing in the
organic solvent, adjacent regions to the prepattern of the resin
layer without being accompanied by an increase in the molecular
weight by heating the prepattern and the resin layer; and removing
regions other than the adjacent regions insolubilized or
desolubilized of the resin layer with the organic solvent, wherein
the resin layer is formed from a composition which contains a
polymer having a solubility in the organic solvent to be decreased
by an action of an acid, and the polymer has a weight average
molecular weight of no less than 13,000 and no greater than
150,000.
[0015] Moreover, still other embodiments of the invention are
directed to:
[0016] a composition for resist pattern-refinement which contains a
polymer having a basic group and having a solubility in an organic
solvent to be decreased by an action of an acid;
[0017] a composition for resist pattern-refinement which contains a
polymer having a solubility in an organic solvent to be decreased
by an action of an acid, and a basic compound; and
[0018] a composition for resist pattern-refinement which contains a
basic compound and an organic solvent, and does not contain a
polymer having a solubility in the organic solvent to be decreased
by an action of an acid.
[0019] According to the pattern-forming methods and the
compositions for resist pattern-refinement of the embodiments of
the present invention, a resist pattern having a fine and favorable
shape can be formed substantially irrespective of the pattern type
by a convenient process. Therefore, these can be suitably used for
pattern formation in the fields of semiconductor processing and the
like in which further progress of miniaturization is expected in
the future. Hereinafter, the embodiments will be explained in
detail.
Pattern-Forming Method
[0020] Hereinafter, the pattern-forming method of an embodiment of
the present invention will be described with reference to FIGS. 1A
to 1D. The pattern-forming method includes the prepattern-forming
step, the resin layer-forming step, the insolubilizing or
desolubilizing step, and the removing step. The pattern-forming
method preferably includes after the prepattern-forming step and
before the resin layer-forming step, the step of bringing into
contact with at least lateral faces of the prepattern, a second
composition (hereinafter, may be also referred to as "composition
(II)") which contains a basic compound and an organic solvent and
which does not contain a polymer having a solubility in the organic
solvent to be decreased by an action of an acid (hereinafter, may
be also referred to as "contacting step"). It is preferred that the
pattern-forming method further includes after the removing step,
the step of rinsing with an organic solvent that is different from
the organic solvent used in the removing step (hereinafter, may be
also referred to as "rinsing step"). Hereinafter, each step will be
described.
Prepattern-Forming Step
[0021] In this step, a prepattern that is insoluble or hardly
soluble in an organic solvent is formed. According to this step, a
prepattern 2 is formed on a substrate 1 as shown in FIG. 1A. The
phrase "insoluble or hardly soluble (insolubilized or
desolubilized) in an (the) organic solvent" as referred to means
that the solubility is low to an extent that the shape of the
prepattern is substantially maintained.
[0022] The organic solvent is exemplified by an alcohol solvent, an
ether solvent, a ketone solvent, an amide solvent, an ester
solvent, a hydrocarbon solvent, and the like.
[0023] Examples of the Alcohol Solvent Include:
[0024] monohydric alcohol solvents such as methanol, ethanol,
n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol,
tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol,
sec-pentanol, tert-pentanol, 3-methoxybutanol, n-hexanol,
2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol,
3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl
alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol,
trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl
alcohol, furfuryl alcohol, phenol, cyclohexanol,
methylcyclohexanol, 3,3,5-trimethylcyclohexanol and benzyl alcohol
and, diacetone alcohol;
[0025] polyhydric alcohol solvents such as ethylene glycol,
1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol,
2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol,
2-ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol,
triethylene glycol and tripropylene glycol;
[0026] polyhydric alcohol partial ether solvents such as ethylene
glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene
glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene
glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene
glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether,
diethylene glycol monoethyl ether, diethylene glycol monopropyl
ether, diethylene glycol monobutyl ether, diethylene glycol
monohexyl ether, propylene glycol monomethyl ether, propylene
glycol monoethyl ether, propylene glycol monopropyl ether,
propylene glycol monobutyl ether, dipropylene glycol monomethyl
ether, dipropylene glycol monoethyl ether and dipropylene glycol
monopropyl ether; and the like.
[0027] Examples of the Ether Solvent Include:
[0028] dialiphatic ethers such as diethyl ether, dipropyl ether and
dibutyl ether;
[0029] diaromatic ethers such as diphenyl ether and ditolyl
ether;
[0030] aromatic-aliphatic ethers such as anisole and phenyl ethyl
ether; and the like.
[0031] Examples of the Ketone Solvent Include:
[0032] aliphatic ketone solvents such as acetone, methyl ethyl
ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl
ketone, methyl-iso-butyl ketone, methyl amyl ketone, ethyl-n-butyl
ketone, methyl-n-hexyl ketone, di-iso-butyl ketone,
trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone,
cyclooctanone, methylcyclohexanone, 2,4-pentanedione,
acetonylacetone and acetophenone;
[0033] aliphatic-aromatic ketone solvents such as acetophenone,
propiophenone and tolylmethyl ketone;
[0034] aromatic ketone solvents such as benzophenone, tolyl phenyl
ketone and ditolyl ketone; and the like.
[0035] Examples of the Amide Solvent Include:
[0036] N,N'-dimethylimidazolidinone, N-methylformamide,
N,N-dimethylformamide, N,N-diethylformamide, acetamide,
N-methylacetamide, N,N-dimethylacetamide, N-methylpropionamide,
N-methylpyrrolidone, and the like.
[0037] Examples of the Ester Solvent include:
[0038] monoester solvents such as methyl acetate, ethyl acetate,
n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl
acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate,
3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate,
2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate,
methylcyclohexyl acetate, n-nonyl acetate, methyl acetoacetate,
ethyl acetoacetate, methoxytriglycol acetate, ethyl propionate,
n-butyl propionate, iso-amyl propionate, methyl lactate, ethyl
lactate, n-butyl lactate and n-amyl lactate;
[0039] diester solvents such as glycol diacetate, diethyl oxalate,
di-n-butyl oxalate, diethyl malonate, dimethyl phthalate and
diethyl phthalate;
[0040] polyhydric alcohol mono ether acetate solvents such as
ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl
ether acetate, diethylene glycol monomethyl ether acetate,
diethylene glycol monoethyl ether acetate, diethylene glycol
mono-n-butyl ether acetate, propylene glycol monomethyl ether
acetate, propylene glycol monoethyl ether acetate, propylene glycol
monopropyl ether acetate, propylene glycol monobutyl ether acetate,
dipropylene glycol monomethyl ether acetate and dipropylene glycol
monoethyl ether acetate;
[0041] lactone solvents such as .gamma.-butyrolactone and
.gamma.-valerolactone;
[0042] carbonate solvents such as diethyl carbonate, dipropyl
carbonate, ethylene carbonate and propylene carbonate; and the
like.
[0043] Examples of the Hydrocarbon Solvent Include:
[0044] aliphatic hydrocarbon solvents such as n-pentane,
iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane,
2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane and
methylcyclohexane;
[0045] aromatic hydrocarbon solvents such as benzene, toluene,
xylene, mesitylene, ethylbenzene, trimethylbenzene,
methylethylbenzene, n-propylbenzene, iso-propylbenzene,
diethylbenzene, iso-butylbenzene, triethylbenzene,
di-iso-propylbenzene and n-amylnaphthalene; and the like.
[0046] Of these, ether solvents, ketone solvents and ester solvents
are preferred. The ether solvent is more preferably an
aromatic-aliphatic ether solvent, and particularly preferably
anisole. The ketone solvent is more preferably an aliphatic ketone
solvent, and particularly preferably methyl amyl ketone. The ester
solvent is more preferably a monoester solvent, and particularly
preferably butyl acetate. These organic solvents may be used in
combination of or two or more types thereof.
[0047] It is preferred that the prepattern contains an acid. When
the prepattern contains an acid, the acid can be diffused from the
prepattern into the resin layer and act therein as described later,
thereby enabling more effective pattern-formation to be
executed.
[0048] The prepattern-forming step preferably includes the steps
of: forming a resist film from a resist composition containing: a
second polymer (hereinafter, may be also referred to as "(a)
polymer" or "polymer (a)") having a solubility in the organic
solvent to be decreased by the action of the acid, a
radiation-sensitive acid generator (hereinafter, may be also
referred to as "(b) acid generator" or "acid generator (b)") and a
solvent (hereinafter, may be also referred to as "(c) solvent" or
"solvent (c)") (hereinafter, may be also referred to as "resist
film-forming step"); exposing the resist film (hereinafter, may be
also referred to as "exposure step"); and developing the exposed
resist film with a developer solution containing the organic
solvent (hereinafter, may be also referred to as "development
step"). Formation of the prepattern by the method having each step
described above enables the prepattern to contain the acid
generated from the acid generator (b) upon the exposure in the
exposure step, and consequently, the pattern-forming method can be
more effectively performed. Each step will be described below.
Resist Film-Forming Step
[0049] In this step, the resist film is formed from the resist
composition containing the polymer (a), the acid generator (b) and
the solvent (c). The resist composition will be described
later.
[0050] The substrate on which the resist film is formed is
exemplified by a conventionally well-known substrate such as a
silicon wafer, a wafer coated with silicon dioxide or aluminum, and
the like. In addition, an organic or inorganic antireflective film
disclosed in, for example, Japanese Examined Patent Application,
Publication No. H6-12452, Japanese Unexamined Patent Application,
Publication No. S59-93448, or the like may be formed on the
substrate. An application procedure is exemplified by spin-coating,
cast coating, roll-coating, and the like. After the application,
soft baking (SB) may be carried out as needed for evaporating the
solvent remaining in the coating film. The temperature for SB is
typically no less than 60.degree. C., and preferably no less than
80.degree. C. The temperature for SB is typically no greater than
140.degree. C., and preferably no greater than 120.degree. C. The
time period for SB is typically no less than 5 sec, and preferably
no less than 10 sec. On the other hand, the time period for PB is
typically no greater than 600 sec, and preferably no greater than
300 sec. The film thickness of the resist film formed is preferably
no less than 10 nm, whereas the film thickness is preferably no
greater than 1,000 nm and, and more preferably no greater than 500
nm.
[0051] In order to preclude influences from basic impurities and
the like contained in the environmental atmosphere, a protective
film disclosed in, for example, Japanese Unexamined Patent
Application, Publication No. H5-188598 and the like may be also
provided on the resist film. Moreover, in order to prevent the
leakage of the acid generator, etc., from the resist film, a
protective film for liquid immersion disclosed in, for example,
Japanese Unexamined Patent Application, Publication No. 2005-352384
and the like may be also provided on the resist film. It is to be
noted that these techniques may be used in combination.
Exposure Step
[0052] In this step, the resist film formed in the resist
film-forming step is exposed. The exposure is carried out by
irradiating the resist film with a radioactive ray through a
photomask (through a liquid immersion medium such as water, as
needed). Examples of the radioactive ray include: electromagnetic
waves such as visible light rays, ultraviolet rays, far ultraviolet
rays, X-rays and y radiations; charged particle beams or charged
particle rays such as electron beams and a-rays; and the like, in
accordance with the line width of the intended pattern. Of these,
far ultraviolet rays and electron beams are preferred, an ArF
excimer laser beam (wavelength: 193 nm), a KrF excimer laser beam
(wavelength: 248 nm) and electron beams are more preferred, and an
ArF excimer laser beam and electron beams are still more
preferred.
[0053] The exposure procedure may be appropriately selected
depending on the shape and the like of the resist pattern desired.
For example, an isolated trench (iso-trench) pattern can be formed
by carrying out exposure at a desired region through a mask of an
isolated line (iso-line) pattern. Also, the exposure may be carried
out at least twice. When the exposure is carried out at least
twice, the twice exposures are preferably carried out continuously.
When the exposure is carried out a plurality of times, for example,
the first exposure is carried out through a line-and-space pattern
mask at a desired region, and subsequently the second exposure is
carried out such that lines cross over light-exposed regions
subjected to the first exposure. The first light-exposed regions
are preferably orthogonal to the second light-exposed regions. Due
to the first light-exposed region and the second light-exposed
region being orthogonal with each other, a perfect circular contact
hole pattern can be easily formed at light-unexposed regions
surrounded by light-exposed regions.
[0054] In a case where the exposure is carried out by liquid
immersion lithography, examples of the liquid immersion liquid for
use in the exposure include water, fluorine-containing inert
liquids, and the like. It is preferred that the liquid immersion
liquid is transparent to an exposure wavelength, and has a
temperature coefficient of the refractive index as small as
possible so that distortion of an optical image projected onto the
film is minimized. In particular, when an ArF excimer laser beam
(wavelength: 193 nm) is used as an exposure light source, it is
preferred to use water in light of availability and ease of
handling thereof in addition to the aforementioned considerations.
When water is used, a slight amount of an additive which reduces
the surface tension of water and imparts enhanced surfactant power
may be added. It is preferred that the additive hardly dissolves a
resist film on a wafer and has a negligible influence on an optical
coating of an inferior face of a lens. The water for use is
preferably distilled water.
[0055] It is preferred that post exposure baking (PEB) is carried
out after the exposure to promote dissociation of the acid-labile
group included in the polymer (a), etc. mediated by the acid
generated from the acid generator (b) upon the exposure in exposed
regions of the resist film. This PEB produces a difference in
solubility of the resist film in a developer solution between the
light-exposed regions and light-unexposed regions. The temperature
for PEB is typically no less than 50.degree. C., and preferably no
less than 80.degree. C. On the other hand, the temperature for PEB
is typically no greater than 180.degree. C., and preferably no
greater than 130.degree. C. The time period for PEB is typically no
less than 5 sec, and preferably no less than 10 sec. On the other
hand, the time period for PEB is typically no greater than 600 sec,
and preferably no greater than 300 sec.
Development Step
[0056] In this step, the resist film exposed above is developed
with a developer solution containing the organic solvent.
Accordingly, a predetermined resist pattern is formed. The
development is typically followed by washing with a rinse agent
such as water or alcohol, and drying.
[0057] The organic solvent contained in the developer solution is
exemplified by solvents similar to those exemplified as the organic
solvent in the prepattern-forming step, and the like. Of these, the
ether solvent, the ester solvent and the ketone solvent are
preferred. The ether solvent is preferably an aromatic
ring-containing ether solvent, and more preferably anisole. The
ester solvent is preferably an acetic acid ester solvent, and more
preferably n-butyl acetate. The ketone solvent is preferably a
chain ketone, and more preferably 2-heptanone.
[0058] The content of the organic solvent in the developer solution
is preferably no less than 80% by mass, more preferably no less
than 90% by mass, still more preferably no less than 95% by mass,
and particularly preferably no less than 99% by mass. When the
content of the organic solvent in the developer solution falls
within the above range, a contrast between the light-exposed
regions and light-unexposed regions can be improved. It is to be
noted that a component other than the organic solvent is
exemplified by water, silicone oil, and the like.
[0059] The developer solution may contain, as needed, a surfactant
in an appropriate amount. As the surfactant, for example, an ionic/
nonionic fluorine and/or silicon surfactant, etc., may be used.
[0060] Examples of the development procedure include: a dipping
procedure in which the substrate is immersed for a given time
period in the developer solution charged in a container; a puddle
procedure in which the developer solution is placed to form a
dome-shaped bead by way of the surface tension on the surface of
the substrate for a given time period to conduct a development; a
spraying procedure in which the developer solution is sprayed onto
the surface of the substrate; a dynamic dispensing procedure in
which the developer solution is continuously applied onto the
substrate that is rotated at a constant speed while scanning with a
developer solution-application nozzle at a constant speed; and the
like.
[0061] The resist film after the development is preferably rinsed
with a rinse agent. Also as the rinse agent in the rinsing step, an
organic solvent may be used, whereby scums which may be generated
can be efficiently washed away. The rinse agent is preferably a
hydrocarbon solvent, a ketone solvent, an ester solvent, an alcohol
solvent, an amide solvent, or the like. Of these, the alcohol
solvent and the ester solvent are preferred, and a monovalent
alcohol solvent having 6 to 8 carbon atoms is more preferred. The
monovalent alcohol having 6 to 8 carbon atoms is exemplified
linear, branched or cyclic monovalent alcohols, and examples
thereof include 1-hexanol, 1-heptanol, 1-octanol,
4-methyl-2-pentanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol,
3-heptanol, 3-octanol, 4-octanol, benzyl alcohol, and the like. Of
these, 1-hexanol, 2-hexanol, 2-heptanol and 4-methyl-2-pentanol are
preferred, and 4-methyl-2-pentanol is more preferred.
[0062] Each component of the rinse agent may be used either alone,
or in combination of two or more thereof The moisture content in
the rinse agent is preferably no greater than 10% by mass, more
preferably no greater than 5% by mass, and still more preferably no
greater than 3% by mass. When the moisture content falls within the
above range, favorable development characteristics can be attained.
It is to be noted that a surfactant may be also added to the rinse
agent.
[0063] The procedure for rinsing with the rinse agent is
exemplified by: a procedure in which the rinse agent is
continuously applied onto the substrate that is rotated at a
constant speed (spin-coating procedure); a procedure in which the
substrate is immersed in a bath filled with the rinse agent for a
given time period (dip coating procedure), a procedure in which the
rinse agent is sprayed on the surface of the substrate (spray
coating procedure), and the like.
[0064] The prepattern formed in this step is exemplified by a
line-and-space pattern, a hole pattern and the like.
Resist Composition
[0065] The resist composition contains the polymer (a), the acid
generator (b) and the solvent (c). In addition to the components
(a) to (c), the resist composition may also contain (d) a polymer
having a greater percentage content of fluorine atoms than that of
the polymer (a) (hereinafter, may be also referred to as "(d)
polymer" or "polymer (d)") and (e) an acid diffusion controller, as
well as other component(s) than these components. Hereinafter, each
component will be described.
(a) Polymer
[0066] The polymer (a) has a solubility in the organic solvent to
be decreased by an action of an acid. The polymer (a) is not
particularly limited as long as the above feature is exhibited, and
is exemplified by a polymer having an acid-labile group
(hereinafter, may be also referred to as "polymer (a`)"), and the
like. The "acid-labile group" as referred to means a group that
substitutes for the hydrogen atom of the acidic group such as a
carboxy group or a hydroxy group and is dissociated by the action
of an acid. When the polymer (a') is employed as the polymer (a), a
pattern having a more favorable shape can be formed according to
the pattern-forming method.
[0067] Structural Unit (I)
[0068] The polymer (a') preferably has a structural unit
(hereinafter, may be also referred to as "structural unit (I)")
that includes an acid-labile group. The structural unit (I) is
exemplified by a structural unit represented by the following
formula (1) and the like.
##STR00001##
[0069] In the above formula (1), R.sup.1 represents a hydrogen
atom, a fluorine atom, a methyl group or a trifluoromethyl group;
and R.sup.p represents a monovalent acid-labile group.
[0070] The monovalent acid-labile group represented by R.sup.p is
preferably a group represented by the following formula (i).
##STR00002##
[0071] In the above formula (i), R.sup.p1 represents a monovalent
hydrocarbon group having 1 to 20 carbon atoms; and R.sup.p2 and
R.sup.p3 each independently represent a monovalent chain
hydrocarbon group having 1 to 20 carbon atoms or a monovalent
alicyclic hydrocarbon having 3 to 20 carbon atoms, or R.sup.p2 and
R.sup.p3 taken together represent an alicyclic structure having 3
to 20 ring atoms together with the carbon atom to which R.sup.p2
and R.sup.p3 bond.
[0072] The monovalent hydrocarbon group having 1 to 20 carbon atoms
represented by R.sup.p1 is exemplified by a monovalent chain
hydrocarbon group having 1 to 20 carbon atoms, a monovalent
alicyclic hydrocarbon group having 3 to 20 carbon atoms, a
monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms,
and the like.
[0073] Examples of the monovalent chain hydrocarbon group having 1
to 20 carbon atoms which may be represented by R.sup.p1, R.sup.p2
and R.sup.p3 include a methyl group, an ethyl group, a n-propyl
group, an i-propyl group, a n-butyl group, a 2-methylpropyl group,
a 1-methylpropyl group, a t-butyl group and the like.
[0074] Examples of the monovalent alicyclic hydrocarbon group
having 3 to 20 carbon atoms which may be represented by R.sup.p1,
R.sup.p2 and R.sup.p3 include:
[0075] cycloalkyl groups such as a cyclopropyl group, a cyclobutyl
group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl
group, a cyclooctyl group, a cyclodecyl group, a cyclododecyl
group, a norbornyl group, an adamantyl group, a tricyclodecyl group
and a tetracyclododecyl group;
[0076] cycloalkenyl groups such as a cyclopropenyl group, a
cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group, a
cyclooctenyl group, a cyclodecenyl group, a norbornenyl group, a
tricyclodecenyl group and a tetracyclododecenyl group; and the
like.
[0077] Examples of the monovalent aromatic hydrocarbon group having
6 to 20 carbon atoms which may be represented by R.sup.p1, R.sup.p2
and R.sup.p3 include:
[0078] aryl groups such as a phenyl group, a tolyl group, a xylyl
group, a naphthyl group and an anthryl group;
[0079] aralkyl groups such as a benzyl group, a phenethyl group and
a naphthylmethyl group; and the like.
[0080] Among these, it is preferred that R.sup.p1 represents a
monovalent chain hydrocarbon group having 1 to 10 carbon atoms; and
R.sup.p2 and R.sup.p3 taken together represent an adamantane
structure or a cycloalkane structure together with the carbon atom
to which R.sup.p2 and R.sup.p3 bond.
[0081] The structural unit (I) is exemplified by structural units
represented by the following formulae (1-1) to (1-4), and the
like.
##STR00003##
[0082] In the above formulae (1-1) to (1-4), R.sup.1 is as defined
in the above formula (1); R.sup.p1, R.sup.p2 and R.sup.p3 are as
defined in the above formula (i); and n.sub.p is an integer of 1 to
4.
[0083] The structural units represented by the above formula(e) (1)
or (1-1) to (1-4) are exemplified by structural units represented
by the following formulae, and the like.
##STR00004## ##STR00005##
[0084] In the above formulae, R.sup.1 is as defined in the above
formula (1).
[0085] Examples of a monomer that gives the structural unit (I)
include a (meth)acrylic acid 2-methyladamantyl-2-yl ester, a
2-ethyladamantyl (meth)acrylate-2-yl ester, a (meth)acrylic
acid-2-methylbicyclo[2.2.1]hept-2-yl ester, a (meth)acrylic
acid-2-ethylbicyclo[2.2.1]hept-2-yl ester, a (meth)acrylic acid
1-(bicyclo[2.2.1]hept-2-yl)-1-methylethyl ester, a (meth)acrylic
acid 1-(adamantan-1-yl)-1-methylethyl ester, a (meth)acrylic acid
1-methyl-1-cyclopentyl ester, a (meth)acrylic acid
1-ethyl-1-cyclopentyl ester, a (meth)acrylic acid
1-methyl-1-cyclohexyl ester, a (meth)acrylic acid
1-ethyl-1-cyclohexyl ester, and the like.
[0086] The lower limit of the proportion of the structural unit (I)
contained with respect to the total structural units constituting
the polymer (a) is preferably 30 mol %, and more preferably 35 mol
%. The upper limit of the proportion is preferably 70 mol %, and
more preferably 65 mol %. When the proportion of the structural
unit (I) falls within the above range, a resist pattern having a
still more favorable shape can be formed according to the
pattern-forming method.
[0087] The polymer (a) preferably has a structural unit (II) that
includes at least one selected from the group consisting of a
lactone structure, a cyclic carbonate structure and a sultone
structure, may have a structural unit (III) that includes a
hydrophilic functional group, and may also have other structural
unit than the structural units described above.
[0088] Structural Unit (II)
[0089] The structural unit (II) includes at least one selected from
the group consisting of a lactone structure, a cyclic carbonate
structure and a sultone structure. When the polymer (a) has the
structural unit (II), the adhesiveness between the prepattern and a
substrate is improved, and consequently a pattern having a more
favorable shape can be formed according to the pattern-forming
method. The structural unit (II) is exemplified by structural units
represented by the following formulae, and the like.
##STR00006## ##STR00007## ##STR00008## ##STR00009##
[0090] In the above formulae, R.sup.L1 represents a hydrogen atom,
a fluorine atom, a methyl group or a trifluoromethyl group.
[0091] The lower limit of the proportion of the structural unit
(II) contained with respect to the total structural units
constituting the polymer (a) is preferably 30 mol %, and more
preferably 35 mol %. The upper limit of the proportion is
preferably 70 mol %, and more preferably 65 mol %. When the
proportion of the structural unit (II) falls within the above
range, the pattern-forming method enables a pattern having a still
more favorable shape to be formed.
[0092] Structural Unit (III)
[0093] The structural unit (III) has a hydrophilic functional
group. When the polymer (a) has the structural unit (III), the
adhesiveness between the prepattern and a substrate is improved,
and consequently, a pattern having a more favorable shape can be
formed according to the pattern-forming method.
[0094] Examples of the hydrophilic functional group include a
hydroxy group, a carboxy group, an amino group, an oxo group
(.dbd.O), a sulfonamide group, a cyano group, a nitro group, and
the like. Of these, the hydroxy group is preferred.
[0095] The structural unit (III) is exemplified by structural units
represented by the following formulae, and the like.
##STR00010## ##STR00011##
[0096] In the above formulae, R.sup.2 represents a hydrogen atom, a
fluorine atom, a methyl group or a trifluoromethyl group.
[0097] The proportion of the structural unit (III) contained with
respect to the total structural units constituting the polymer (a)
is preferably no less than 0 mol % and no greater than 40 mol %,
and more preferably no less than 0 mol % and no greater than 30 mol
%. When the proportion of the structural unit (III) falls within
the above range, a resist pattern having a still more favorable
shape can be formed according to the pattern-forming method.
[0098] The polymer (a) may also have other structural unit than the
structural units described above. The other structural unit is
exemplified by a structural unit that includes an acid-nonlabile
alicyclic hydrocarbon group, and the like. The proportion of the
other structural unit contained with respect to the total
structural units constituting the polymer (a) is preferably no less
than 0 mol % and no greater than 30 mol %, and more preferably no
less than 0 mol % and no greater than 20 mol %.
[0099] The content of the polymer (a) in the total solid content of
the resist composition is preferably no less than 70% by mass, more
preferably no less than 80% by mass, and still more preferably no
less than 85% by mass.
Synthesis Method of Polymer (a)
[0100] The polymer (a) may be synthesized by, for example,
polymerizing monomers that give each structural unit in an
appropriate solvent using a radical polymerization initiator.
[0101] Examples of the radical polymerization initiator include:
azo radical initiators such as 2,2'-azobisisobutyronitrile (AIBN),
2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile),
2,2'-azobis(2-cyclopropylpropionitrile),
2,2'-azobis(2,4-dimethylvaleronitrile) and dimethyl
2,2'-azobisisobutyrate; peroxide radical initiators such as benzoyl
peroxide, t-butyl hydroperoxide and cumene hydroperoxide; and the
like. Of these, AIBN and dimethyl 2,2'-azobisisobutyrate are
preferred. These radical initiators may be used as a mixture of two
or more types thereof.
[0102] Examples of the solvent used in the polymerization
include:
[0103] alkanes such as n-pentane, n-hexane, n-heptane, n-octane,
n-nonane and n-decane;
[0104] cycloalkanes such as cyclohexane, cycloheptane, cyclooctane,
decalin and norbornane;
[0105] aromatic hydrocarbons such as benzene, toluene, xylene,
ethylbenzene and cumene;
[0106] halogenated hydrocarbons such as chlorobutanes,
bromohexanes, dichloroethanes, hexamethylene dibromide and
chlorobenzene;
[0107] saturated carboxylic acid esters such as ethyl acetate,
n-butyl acetate, i-butyl acetate and methyl propionate;
[0108] ketones such as acetone, methyl ethyl ketone,
4-methyl-2-pentanone and 2-heptanone;
[0109] ethers such as tetrahydrofuran, dimethoxyethanes and
diethoxyethanes;
[0110] alcohols such as methanol, ethanol, 1-propanol, 2-propanol
and 4-methyl-2-pentanol; and the like. These solvents may be used
either alone, or two or more types thereof may be used in
combination.
[0111] The reaction temperature in the polymerization is typically
no less than 40.degree. C., and preferably no less than 50.degree.
C., whereas the reaction temperature is typically no greater than
150.degree. C., and preferably no greater than 120.degree. C. The
reaction time period is typically no less than 1 hour, whereas the
reaction time period is typically no greater than 48 hrs, and
preferably no greater than 24 hrs.
[0112] The weight average molecular weight (Mw) of the polymer (a)
as determined by gel permeation chromatography (GPC) is preferably
no less than 1,000. Whereas, the weight average molecular weight
(Mw) is preferably no greater than 100,000, more preferably no
greater than 50,000, and particularly preferably no greater than
30,000. When the Mw of the polymer (a) falls within the above
range, a pattern having a still more favorable shape can be formed
according to the pattern-forming method.
[0113] The ratio (Mw/Mn) of the Mw to the number average molecular
weight (Mn) of the polymer (a) is typically no less than 1 and no
greater than 3, and preferably no less than 1 and no greater than
2.
[0114] The Mw and the Mn of the polymer are determined GPC using
GPC columns available from Tosoh Corporation ("G2000 HXL".times.2,
"G3000 HXL".times.1, and "G4000 HXL".times.1), under the following
conditions.
[0115] eluent: tetrahydrofuran (available from Wako Pure Chemical
Industries, Ltd.);
[0116] flow rate: 1.0 mL/min;
[0117] sample concentration: 1.0% by mass;
[0118] amount of injected sample: 100 .mu.L;
[0119] detector: differential refractometer; and
[0120] standard substance: mono-dispersed polystyrene
(b) Acid Generator
[0121] The acid generator (b) is a substance that generates an acid
upon an exposure. The polymer (a) has a solubility in an organic
solvent to be decreased by the action of the acid generated from
the acid generator (b) through e.g., a dissociation of the
acid-labile group. As a result, a prepattern that is insoluble or
hardly soluble in the organic solvent can be formed. In addition,
the prepattern may contain an acid generated upon the exposure from
the acid generator (b). As a result, a resist pattern having a fine
and favorable shape can be more effectively formed according to the
pattern-forming method. The acid generator (b) may be contained in
the resist composition in the form of a low molecular weight
compound as described later (hereinafter, may be also referred to
as "(b) acid generating agent" or "acid generating agent (b)", as
appropriate), in the form incorporated into the polymer, or in both
of these forms.
[0122] The acid generating agent (b) is exemplified by onium salt
compounds, N-sulfonyloxyimide compounds, and the like.
[0123] Examples of the onium salt compounds include sulfonium
salts, tetrahydrothiophenium salts, iodonium salts, and the
like.
[0124] Examples of the sulfonium salt include triphenylsulfonium
trifluoromethanesulfonate, triphenylsulfonium
nonafluoro-n-butanesulfonate, triphenylsulfonium
perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1
]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium
2-bicyclo[2.2.1]hept-2-yl-1,1-difluoroethanesulfonate,
triphenylsulfonium camphorsulfonate,
4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate,
4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate,
4-cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate,
4-cyclohexylphenyldiphenylsulfonium
2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate,
4-cyclohexylphenyldiphenylsulfonium camphorsulfonate,
4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate,
4-methanesulfonylphenyldiphenylsulfonium
nonafluoro-n-butanesulfonate,
4-methanesulfonylphenyldiphenylsulfonium
perfluoro-n-octanesulfonate,
4-methanesulfonylphenyldiphenylsulfonium 2-bicyclo [2.2. 1
]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate,
4-methanesulfonylphenyldiphenylsulfonium camphorsulfonate,
triphenylsulfonium
1,1,2,2-tetrafluoro-6-(1-adamantanecarbonyloxy)-hexane-1-sulfonate,
triphenylsulfonium 2-(1-adamantyl)-1,1-difluoroethanesulfonate, and
the like.
[0125] Examples of the tetrahydrothiophenium salt include
1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium
trifluoromethanesulfonate,
1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium
nonafluoro-n-butanesulfonate,
1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium
perfluoro-n-octanesulfonate,
1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium
2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate,
1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium
camphorsulfonate,
1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium
trifluoromethanesulfonate,
1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium
nonafluoro-n-butanesulfonate,
1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium
perfluoro-n-octanesulfonate,
1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium
2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate,
1-(6-n-butoxynaphthalen-2-yl)tetrahydrothiophenium
camphorsulfonate,
1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium
trifluoromethanesulfonate,
1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium
nonafluoro-n-butanesulfonate,
1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium
perfluoro-n-octanesulfonate,
1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium
2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate,
1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium
camphorsulfonate, and the like.
[0126] Examples of the iodonium salt include diphenyliodonium
trifluoromethanesulfonate, diphenyliodonium
nonafluoro-n-butanesulfonate, diphenyliodonium
perfluoro-n-octanesulfonate, diphenyliodonium
2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate,
diphenyliodonium camphorsulfonate, bis(4-t-butylphenyl)iodonium
trifluoromethanesulfonate, bis(4-t-butylphenyl)iodonium
nonafluoro-n-butanesulfonate, bis(4-t-butylphenyl)iodonium
perfluoro-n-octanesulfonate, bis(4-t-butylphenyl)iodonium
2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate,
bis(4-t-butylphenyl)iodonium camphorsulfonate, and the like.
[0127] Examples of the N-sulfonyloxyimide compound include
N-(trifluoromethanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimid-
e,
N-(nonafluoro-n-butanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarbox-
yimide,
N-(perfluoro-n-octanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dica-
rboxyimide,
N-(2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy)bicyclo
[2.2. 1] hept-5- ene-2,3-dicarboxyimide,
N-(2-(3-tetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]dodecanyl)-1,1-difluoroetha-
nesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,
N-(camphorsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide,
and the like.
[0128] The acid generating agent (b) is preferably the onium salt
compound, and more preferably the sulfonium salt. The acid
generating agent (b) may be used either one or two or more types
thereof.
[0129] The content of the acid generator (b) with respect to 100
parts by mass of the polymer (a) is, in a case where the acid
generator (b) is the acid generating agent (b), typically no less
than 0.1 parts by mass, and preferably no less than 0.5 parts by
mass. Whereas, the content is typically no greater than 20 parts by
mass, and preferably no greater than 15 parts by mass. When the
content of the acid generating agent (b) is less than the lower
limit, the sensitivity and developability of the resist composition
may be deteriorated. On the other hand, when the content of the
acid generating agent (b) is greater than the upper limit,
transparency to the radioactive rays are impaired, whereby a
desired resist pattern may be hardly obtained.
(c) Solvent
[0130] Any solvent may be used as the solvent (c) without being
particularly limited as long as the polymer (a), the acid generator
(b) and the other component can be dissolved or dispersed therein.
The solvent (c) is exemplified by similar solvents to those
exemplified as the organic solvent for use in the
prepattern-forming step, and the like.
[0131] Of these, the solvent (c) is preferably the ester solvent
and the ketone solvent. As the ester solvent, the polyhydric
alcohol mono ether acetate solvents and lactone solvents are
preferred, and propylene glycol monomethyl ether acetate and
.gamma.-butyrolactone are more preferred. As the ketone solvent,
cyclic ketone solvents are preferred, and cyclohexanone is more
preferred.
(d) Polymer
[0132] The polymer (d) has a greater percentage content of fluorine
atoms than that of the polymer (a). In a case where the resist
composition contains the polymer (d), when a resist film is formed,
oil repellent characteristics of the polymer (d) tend to allow the
polymer (d) to be localized in the surface region of the resist
film. As a result, when liquid immersion lithography is carried
out, it is preferred in that elution of the acid generating agent,
the acid diffusion control agent and the like into the liquid
immersion medium may be inhibited. In addition, due to water
repellent characteristics of the polymer (d), an advancing contact
angle of a liquid immersion medium on the resist film can be
controlled to fall within a desired range, whereby generation of
bubble defects can be inhibited. Further, a greater receding
contact angle of the liquid immersion medium on the resist film is
attained, whereby an exposure by high speed scanning without being
accompanied by residual water beads is enabled. It is to be noted
that the percentage content (% by mass) of fluorine atoms may be
calculated based on the structure of the polymer determined by
.sup.13C-NMR, .sup.1H-NMR, IR spectrum and the like.
[0133] The polymer (d) is not particularly limited as long as the
percentage content of fluorine atoms thereof is greater than that
of the polymer (a), and preferably has a fluorinated alkyl group.
The polymer (d) is prepared by polymerizing at least one or more
types of monomers that include a fluorine atom in the structure
thereof. The monomers that include a fluorine atom in the structure
thereof are exemplified by a monomer that includes a fluorine atom
in its main chain, a monomer that includes a fluorine atom in its
side chain, and a monomer that includes a fluorine atom in its main
chain and side chain.
[0134] Examples of the monomer that includes a fluorine atom in its
main chain include .alpha.-fluoroacrylate compounds,
.alpha.-trifluoromethylacrylate compounds, .beta.-fluoroacrylate
compounds, .beta.-trifluoromethylacrylate compounds, .alpha.,62
-fluoroacrylate compounds, .alpha.,.beta.-trifluoromethylacrylate
compounds, compounds derived by substituting a hydrogen atom of one
or more types of vinyl moieties by a fluorine atom, a
trifluoromethyl group, etc., and the like.
[0135] Examples of the monomer that includes a fluorine atom in its
side chain include: compounds in which an alicyclic olefin compound
such as norbornene has a fluorine atom, or a fluoroalkyl group or a
derivative thereof as a side chain; ester compounds of acrylic acid
or methacrylic acid with a fluoroalkyl group or a derivative
thereof; monomers in which olefins having a fluorine atom, or a
fluoroalkyl group or a derivative thereof as one or more types of
side chain (a site excluding a double bond), and the like.
[0136] Example of the monomer that includes a fluorine atom in its
main chain and side chain include: ester compounds of
.alpha.-fluoroacrylic acid, .beta.-fluoroacrylic acid, .alpha.,62
-fluoroacrylic acid, .alpha.-trifluoromethylacrylic acid,
.beta.-trifluoromethylacrylic acid, .alpha.,62
-trifluoromethylacrylic acid or the like with a fluoroalkyl group
or a derivative thereof; monomers derived by substituting hydrogen
atom(s) of one or more types of vinyl moieties by a fluorine atom
or a trifluoromethyl group and substituting a side chain of the
compound with a fluorine atom, or a fluoroalkyl group or a
derivative thereof; monomers in which alicyclic olefin compounds
derived by substituting hydrogen atom(s) bonded to one or more
types of double bonds by a fluorine atom or a trifluoromethyl
group, etc., and having a fluorinated alkyl group or a derivative
thereof as a side chain; and the like. The alicyclic olefin
compound as referred to herein means a compound that includes a
double bond in a part of its ring.
[0137] It is preferred that the polymer (d) includes the fluorine
atom by having a structural unit (IV) represented by the following
formula (F1).
##STR00012##
[0138] In the above formula (F1), R.sup.3 represents a hydrogen
atom, a fluorine atom, a methyl group or a trifluoromethyl group;
R.sup.4 represents a linear or branched alkyl group having 1 to 6
carbon atoms and having at least one fluorine atoms, or a
monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms
and having at least one fluorine atoms, or a derivative group
thereof; k is an integer of 1 to 3, wherein in a case where R.sup.4
is present in a plurality of number, a plurality of R.sup.4s may be
identical or different; and A represents a single bond or a linking
group having a valency of (k+1).
[0139] Examples of the linking group having a valency of (k+1)
which may be represented by A include an oxygen atom, a sulfur
atom, a carbonyloxy group, an oxycarbonyl group, an amide group, a
sulfonylamide group, a urethane group, a
carbonyloxy-di(oxycarbonyl)ethanediyl group, a
carbonyloxy-di(oxycarbonyl)propanediyl group, a
tri(carbonyloxy)ethanediyl group, a
carbonyloxy-tri(oxycarbonyl)ethanediyl group, a
carbonyloxy-tri(oxycarbonyl)propanediyl group, a
tetra(carbonyloxy)ethanediyl group, and the like.
[0140] Examples of preferred monomers that give the structural unit
(IV) include (meth)acrylic acid trifluoromethyl ester,
(meth)acrylic acid 2,2,2-trifluoroethyl ester, (meth)acrylic acid
perfluoroethyl ester, (meth)acrylic acid perfluoro-n-propyl ester,
(meth)acrylic acid perfluoro-i-propyl ester, (meth)acrylic acid
perfluoro-n-butyl ester, (meth)acrylic acid perfluoro-i-butyl
ester, (meth)acrylic acid perfluoro-t-butyl ester, (meth)acrylic
acid 2-(1,1,1,3,3,3-hexafluoropropyl) ester, (meth)acrylic acid
1-(2,2,3,3,4,4,5,5-octafluoropentyl) ester, (meth)acrylic acid
perfluorocyclohexylmethyl ester, (meth)acrylic acid
1-(2,2,3,3,3-pentafluoropropyl) ester, (meth)acrylic acid
1-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl)
ester, (meth)acrylic acid
1-(5-trifluoromethyl-3,3,4,4,5,6,6,6-octafluorohexyl) ester and
(meth)acrylic acid 2,2-di(2,2,2-trifluoroethyloxycarbonyl)ethyl
ester, and the (meth)acrylic acid 2,2,2-trifluoroethyl ester and
the (meth)acrylic acid 2,2-di(2,2,2-trifluoroethyloxycarbonyl)ethyl
ester are more preferred.
[0141] The polymer (d) may have two or more types of the structural
unit (IV). The proportion of the structural unit (IV) contained
with respect to the total structural units in the polymer (d) is
typically no less than 5 mol %, preferably no less than 10 mol %,
and more preferably no less than 15 mol %. When the proportion of
the structural unit (IV) is less than 5 mol %, the receding contact
angle of no less than 70.degree. may not be achieved, and/or
elution of the acid generating agent and the like from the resist
coating film may not be inhibited.
[0142] In addition to the structural unit (IV), in order to control
rates of dissolution in developer solutions, the polymer (d) may
have at least one type of other structural units such as, for
example: the structural unit (I) in the polymer (a) that includes
an acid-labile group; the structural unit (II) in the polymer (a)
that includes at least one selected from the group consisting of a
lactone structure, a cyclic carbonate structure and a sultone
structure; and a structural unit that includes an alicyclic
hydrocarbon group.
[0143] The structural unit that includes an alicyclic hydrocarbon
group is exemplified by a structural unit represented by the
following formula (F2), and the like.
##STR00013##
[0144] In the above formula (F2), R.sup.5 represents a hydrogen
atom, a fluorine atom, a methyl group or a trifluoromethyl group;
and G represents a monovalent alicyclic hydrocarbon group having 4
to 20 carbon atoms.
[0145] The monovalent alicyclic hydrocarbon group having 4 to 20
carbon atoms represented by G is exemplified by hydrocarbon groups
having an alicyclic ring derived from a cycloalkane such as
cyclobutane, cyclopentane, cyclohexane, bicyclo[2.2.1]heptane,
bicyclo[2.2.2]octane, tricyclo[5.2.1.0.sup.2,6]decane,
tetracyclo[6.2.1.1.sup.3,6.0.sup.2,7]dodecane or
tricyclo[3.3.1.1.sup.3,7]decane.
[0146] The proportion of the other structural unit contained with
respect to the total structural units constituting the polymer (d)
is typically no greater than 90 mol %, and preferably no greater
than 80 mol %.
[0147] The content of the polymer (d) with respect to 100 parts by
mass of the polymer (a) is preferably no less than 0.1 parts by
mass, and more preferably no less than 1 part by mass. On the other
hand, the content is preferably no greater than 20 parts by mass,
and more preferably no greater than 10 parts by mass. When the
content of the polymer (d) falls within the above range, water
repellency of the surface of the formed resist film can be more
appropriately increased.
[0148] Synthesis Method of Polymer (d)
[0149] With respect to the synthesis method of the polymer (d), for
example, a similar method to the synthesis method of the polymer
(a) may be employed to enable the polymer (d) to be synthesized.
The Mw of the polymer (d) is preferably no less than 1,000, whereas
the Mw is preferably no greater than 50,000, more preferably no
greater than 30,000, and still more preferably no greater than
10,000. When the Mw of the polymer (d) is less than 1,000, a
satisfactory advancing contact angle may not be obtained.
(e) Acid Diffusion Controller
[0150] The acid diffusion controller (e) achieves the effect of
controlling a diffusion phenomenon of the acid, etc., generated
from the acid generator (b) upon an exposure in the resist film,
and inhibiting unfavorable chemical reactions at light-unexposed
regions. In addition, the acid diffusion controller (e) also
achieves the effect of improving the storage stability of the
resist composition containing the same. The acid diffusion
controller (e) may be contained in the resist composition in the
form of a free compound (hereinafter, may be also referred to as
"(e) acid diffusion control agent" or "acid diffusion control agent
(e)", as appropriate), or in the form incorporated as a part of the
polymer, or in both of these forms.
[0151] The acid diffusion control agent (e) is exemplified by an
amine compound, an amide group-containing compound, a urea
compound, a nitrogen-containing heterocyclic compound, and the
like.
[0152] Examples of the amine compound include mono
(cyclo)alkylamines; di(cyclo)alkylamines; tri(cyclo)alkylamines;
substituted alkylanilines and derivatives thereof; ethylenediamine,
N,N,N',N'-tetramethylethylenediamine, tetramethylenediamine,
hexamethylenediamine, 4,4'-diaminodiphenylmethane,
4,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone,
4,4'-diaminodiphenylamine, 2,2-bis(4-aminophenyl)propane,
2-(3-aminophenyl)-2-(4-aminophenyl)propane,
2-(4-aminophenyl)-2-(3-hydroxyphenyl)propane,
2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane,
1,4-bis(1-(4-aminophenyl)-1-methylethyl)benzene,
1,3-bis(1-(4-aminophenyl)-1-methylethyl)benzene,
bis(2-dimethylaminoethyl) ether, bis(2-diethylaminoethyl) ether,
1-(2-hydroxyethyl)-2-imidazolidinone,
N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine,
N,N,N',N'',N''-pentamethyldiethylenetriamine, and the like.
[0153] Examples of the amide group-containing compound include
N-t-butoxycarbonyl group-containing amino compounds such as
N-(t-butoxycarbonyl)-4-hydroxypiperidine N-t-pentyloxycarbonyl
group-containing amino compounds such as
N-(t-pentyloxycarbonyl)-4-hydroxypiperidineformamide,
N-methylformamide, N,N-dimethylformamide, acetamide,
N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide,
pyrrolidone, N-methylpyrrolidone, N-acetyl-1-adamantylamine,
tris(2-hydroxyethyl) isocyanurate, and the like.
[0154] Examples of the urea compound include urea, methylurea,
1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea,
1,3-diphenylurea, tri-n-butylthiourea, and the like.
[0155] Examples of the nitrogen-containing heterocyclic compound
include imidazoles; pyridines; piperazines; pyrazine, pyrazole,
pyridazine, quinoxaline, purine, pyrrolidine, piperidine,
piperidineethanol, 2-quinoxalinol, 3-piperidino-1,2-propanediol,
morpholine, 4-methylmorpholine, 1-(4-morpholinyl)ethanol,
4-acetylmorpholine, 3-(N-morpholino)-1,2-propanediol,
1,4-dimethylpiperazine, 1,4-diazabicyclo[2.2.2]octane, and the
like.
[0156] A photolabile base which is sensitized upon an exposure to
generate a weak acid may be used as the acid diffusion control
agent (e). The photolabile base is exemplified by an onium salt
compound that loses acid diffusion controllability through
degradation upon an exposure, and the like. The onium salt compound
is exemplified by a sulfonium salt compound represented by the
following formula (K1), an iodonium salt compound represented by
the following formula (K2), and the like.
##STR00014##
[0157] In the above formulae (K1) and (K2), R.sup.6 to R.sup.10
each independently represent a hydrogen atom, an alkyl group, an
alkoxy group, a hydroxyl group or a halogen atom; and Z.sup.- and
E.sup.- represent OH.sup.-, R.sup.A--COO.sup.-,
R.sup.A--SO.sub.3.sup.-, R.sup.A--N.sup.---SO.sub.2--R.sup.B or an
anion represented by the following formula (K3), wherein R.sup.A
represents an alkyl group, an aryl group or an alkaryl group; and
R.sup.B represents an alkyl group which may have a fluorine
atom.
##STR00015##
[0158] In the above formula (K3), R.sup.11 represents a linear or
branched alkyl group having 1 to 12 carbon atoms, or a linear or
branched alkoxyl group having 1 to 12 carbon atoms, wherein a part
or all of hydrogen atoms included in the linear or branched alkyl
group or the linear or branched alkoxyl group may be substituted
with a fluorine atom; and u is an integer of 0 to 2.
Other Components
[0159] In addition to the components (a) to (e) described above,
the resist composition may contain other component. The other
component is exemplified by a surfactant, a sensitizing agent and
the like.
[0160] Surfactant
[0161] The surfactant achieves the effect of improving the
application property, striation, developability, and the like. As
the surfactant, any surfactant similar to those used in general
resist compositions may be used.
[0162] Sensitizing Agent
[0163] The sensitizing agent exhibits the action of increasing the
amount of the acid generated from the acid generator (b) or the
like, and achieves the effect of improving "apparent sensitivity"
of the resist composition.
[0164] Examples of the sensitizing agent include carbazoles,
acetophenones, benzophenones, naphthalenes, phenols, biacetyl,
eosin, rose bengal, pyrenes, anthracenes, phenothiazines, and the
like. These sensitizing agents may be used in combination of two or
more types thereof
Preparation Method of Resist Composition
[0165] The resist composition may be prepared, for example, by
mixing the polymer (a), the acid generator (b), the solvent (c) and
favorable component(s) in a certain ratio. The total solid content
concentration of the resist composition is typically no less than
1% by mass and no greater than 50% by mass, and preferably no less
than 1% by mass and no greater than 25% by mass.
[0166] As an alternative to the prepattern-forming step described
above, this step may be carried out by the steps of, for example:
forming a resist film from the aforementioned resist composition;
exposing the resist film; thereafter developing the exposed resist
film with an alkaline developer solution such as an aqueous
tetramethylammonium hydroxide solution; and subjecting thus
developed resist film to an overall-exposure.
Contacting Step
[0167] In this step, at least lateral faces of the prepattern are
brought into contact with the composition (II) which contains the
basic compound and the organic solvent and which does not contain
the polymer having a solubility in the organic solvent to be
decreased by the action of the acid. When this contacting step is
included, the shape of the formed pattern can be more favorable
according to the pattern-forming method. This advantage is presumed
to result from, for example, adhesion of the basic compound to the
prepattern by bringing the composition (II) into contact with the
at least lateral faces of the prepattern, followed by formation of
regions including anionic groups such as a carboxylate group in
adjacent regions formed in subsequent resin layer-forming step and
insolubilizing or desolubilizing step, wherein the anionic groups
are derived from the acidic groups such as the carboxy group
constituting the adjacent regions, due to the basic compound,
thereby leading to an increase of the extent of the
desolubilization of the adjacent regions in the organic solvent
used in the removing step.
[0168] The basic compound contained in the composition (II) is not
particularly limited as long as it is basic, and is exemplified by
compounds similar to those exemplified as (q) a basic compound
contained in a composition (I-B) described later, and the like.
[0169] The organic solvent contained in the composition (II) is
exemplified by organic solvents similar to those exemplified in
connection with the prepattern-forming step, and the like.
[0170] The polymer, which is not contained in the composition (II),
having a solubility in the organic solvent to be decreased by the
action of the acid is exemplified by polymers similar to those
exemplified as the polymer (a) involved in the prepattern-forming
step, and the like.
[0171] The composition (II) may contain other component(s) in
addition to the basic compound and the organic solvent, and for
example, a surfactant and the like may be contained.
[0172] The lower limit of the content of the basic compound in the
composition (II) is preferably 0.01% by mass, more preferably 0.05%
by mass, still more preferably 0.1% by mass, and particularly
preferably 0.2% by mass. The upper limit of the content is
preferably 10% by mass, more preferably 5% by mass, still more
preferably 1% by mass, and particularly preferably 0.5% by
mass.
[0173] The procedure for bringing the composition (II) into contact
with the at least lateral faces of the prepattern is exemplified by
spin coating and the like.
Resin Layer-Forming Step
[0174] In this step, a resin layer is formed on at least lateral
faces of the prepattern. This resin layer contains the polymer (I)
and is formed from the composition (I), and involves at least one
selected from the following features (i) and (ii):
[0175] (i) the polymer (I) having a basic group; and
[0176] (ii) the composition (I) further containing a basic
compound.
[0177] According to this step, a resin layer 3 is formed on at
least lateral faces of the prepattern 2 as shown in FIG. 1B. The
composition (I) may be either a composition (I-A) involving the
feature (i), or a composition (I-B) involving the feature (ii).
According to the pattern-forming method, a pattern having a fine
and favorable shape can be formed substantially irrespective of the
pattern type by using the composition (I). This advantage is
presumed to result from, for example, conversion of the acidic
groups such as the carboxy group of the polymer in adjacent regions
formed in the insolubilizing or desolubilizing step, wherein the
polymer constitutes the adjacent regions, into anionic groups such
as a carboxylate group, due to the basicity of the composition (I)
involving the feature (i) or (ii), thereby making the adjacent
regions more hardly soluble in the organic solvent used in the
removing step.
[0178] The polymer (I), the composition (I-A) and the composition
(I-B) will follow in this order.
[0179] Polymer (I)
[0180] The polymer (I) has a solubility in the organic solvent to
be decreased by an action of an acid. The polymer (I) is not
particularly limited as long as the above property is exhibited,
and is exemplified by examples of the polymer (a) in connection
with the prepattern-forming step, and the like.
[0181] It is preferred that the polymer (I) has an acid-labile
group such that the solubility in the organic solvent can be more
effectively decreased by an action of an acid (hereinafter, the
polymer having an acid-labile group may be also referred to as
"polymer (I')"). The structural unit that includes an acid-labile
group (hereinafter, may be also referred to as "structural unit
(A)") is exemplified by the structural unit (I) of the polymer (a')
contained in the resist composition, and the like. The structural
unit (A) may or may not include an aromatic ring.
[0182] The lower limit of the proportion of the structural unit (A)
contained with respect to the total structural units constituting
the polymer (I) is preferably 10 mol %, more preferably 30 mol %,
and still more preferably 40 mol %. The upper limit of the
proportion is preferably 80 mol %, more preferably 70 mol %, and
still more preferably 60 mol %.
[0183] The polymer (I) preferably has a structural unit
(hereinafter, may be also referred to as "structural unit (B)")
that includes an aromatic ring having 6 to 30 carbon atoms. When
the polymer (I) has the structural unit (B), a pattern that is
superior in etching resistance can be formed according to the
pattern-forming method.
[0184] Examples of the aromatic ring having 6 to 30 carbon atoms
include a benzene ring, a naphthalene ring, an anthracene ring, a
phenanthrene ring, a pyrene ring, a chrysene ring, a tetracene
ring, a pentacene ring and the like. Of these, in light of possible
formation of a pattern having a more fine and favorable shape, the
aromatic ring having 6 to 15 carbon atoms is preferred, and the
benzene ring and the naphthalene ring are more preferred.
[0185] In addition to a linking group between the aromatic ring and
the main chain of the polymer (I), a substituent that substitutes
for hydrogen atom(s) on the ring may be bonded to the aromatic
ring.
[0186] Examples of the Substituent Include:
[0187] hydrocarbon groups such as a chain hydrocarbon group, an
alicyclic hydrocarbon group and an aromatic hydrocarbon group;
[0188] halogen atoms such as a fluorine atom, a chlorine atom, a
bromine atom and an iodine atom;
[0189] a hydroxy group, an amino group, sulfanyl group, a nitro
group and a cyano group;
[0190] oxyhydrocarbon groups such as an alkoxy group, a
cycloalkyloxy group and an aryloxy group;
[0191] acyl groups such as an alkylcarbonyl group, a
cycloalkylcarbonyl group and an arylcarbonyl group;
[0192] carbonyloxyhydrocarbon groups such as an alkoxycarbonyloxy
group, a cycloalkyloxycarbonyloxy group and an aryloxycarbonyloxy
group;
[0193] sulfonylhydrocarbon groups such as an alkylsulfonyl group, a
cycloalkylsulfonyl group and an arylsulfonyl group; and the
like.
[0194] Examples of the Monomer that Gives a Structural Unit (B)
Include:
[0195] vinylaromatic hydrocarbons such as styrene, vinylnaphthalene
and vinylanthracene, and substituted forms of the same;
[0196] aryl (meth)acrylate esters such as a phenyl (meth)acrylate
ester, a naphthyl (meth)acrylate ester and an anthryl
(meth)acrylate ester, and substituted forms of the same;
[0197] acenaphthylene and substituted forms thereof; and the
like.
[0198] The lower limit of the proportion of the structural unit (B)
contained with respect to the total structural units constituting
the polymer (I-A) is 20 mol %, preferably 25 mol %, more preferably
30 mol %, still more preferably 40 mol %, and particularly
preferably 50 mol %. The upper limit of the proportion is
preferably 100 mol %, more preferably 80 mol %, still more
preferably 70 mol %, and particularly preferably 60 mol %. When the
proportion of the structural unit (B) falls within the above range,
favorable shape of the resist pattern and etching resistance can be
both attained at a higher level.
[0199] The polymer (I) may have any of various groups other than
the aromatic ring and the acid-labile group. In light of an
adjustment of dissolution and insolubilization of the resin layer
formed by the pattern-forming method, it is preferred that the
polymer (I) further has at least one selected from the set
consisting of a hydroxy group, a carboxy group, an oxo group, a
group having a lactone structure, a group having a cyclic carbonate
structure, and a group having a sultone structure. These groups may
be included in the structural unit (A) or the structural unit (B),
or may be included in other structural unit except for the
structural unit (A) and the structural unit (B).
[0200] The lower limit of the Mw of the polymer (I) is preferably
13,000, more preferably 15,000, still more preferably 17,000,
particularly preferably 20,000, and further particularly 23,000.
The upper limit of the Mw of the polymer (I) is preferably 150,000,
more preferably 100,000, still more preferably 80,000, particularly
preferably 50,000, and further particularly preferably 30,000. When
the Mw falls within the above range, a pattern having a finer and
more favorable shape can be formed according to the pattern-forming
method. When the Mw is less than 13,000, the shape of the pattern
formed by the pattern-forming method may be deteriorated. Further,
when the Mw is greater than 150,000, the preparation of the
composition (I) may be difficult.
Composition (I-A)
[0201] The composition (I-A) contains a polymer (I) having a basic
group and having a solubility in the organic solvent to be
decreased by an action of an acid (hereinafter, the polymer (I) may
be also referred to as "polymer (I-A)"). The composition (I-A)
preferably contains a solvent (i) in addition to the polymer (I-A),
and may further contain other component such as e.g., acid
incrementor. Each component will be described in the following.
[0202] Polymer (I-A)
[0203] The polymer (I-A) in (i) has a basic group and has a
solubility in the organic solvent to be decreased by an action of
an acid. In this polymer (I-A), a basic group is bonded to the
polymer (I). The polymer (I-A) preferably has an acid-labile group
and the basic group (hereinafter, the polymer (I-A) having such a
feature may be also referred to as "polymer (I'-A)").
[0204] The basic group is not particularly limited as long as it
has basicity, and is exemplified by a group represented by the
following formula (a) (hereinafter, may be also referred to as
"group (a)"), a group represented by the following formula (b)
(hereinafter, may be also referred to as "group (b)"), and the
like.
##STR00016##
[0205] In the above formula (b), L represents a single bond, a
divalent chain hydrocarbon group having 1 to 20 carbon atoms or a
divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms;
and R.sup.A and R.sup.B each independently represent a hydrogen
atom, a monovalent chain hydrocarbon group having 1 to 20 carbon
atoms or a monovalent alicyclic hydrocarbon group having 3 to 20
carbon atoms, or L and R.sup.A may taken together represent an
aliphatic heterocyclic structure having 3 to 20 ring atoms together
with the nitrogen atom to which L and R.sup.A bond.
[0206] Examples of the divalent chain hydrocarbon group having 1 to
20 carbon atoms which may be represented by L include:
[0207] alkanediyl groups such as a methanediyl group, an ethanediyl
group and a propanediyl group;
[0208] alkenediyl groups such as an ethenediyl group, a propenediyl
group and a butenediyl group;
[0209] alkynediyl groups such as an ethynediyl group, a propenediyl
group and a butynediyl group; and the like.
[0210] Examples of the divalent alicyclic hydrocarbon group having
3 to 20 carbon atoms which may be represented by L include:
[0211] cycloalkanediyl groups such as a cyclopropanediyl group, a
cyclobutanediyl group, a cyclopentanediyl group, a cyclohexanediyl
group, a cyclooctanediyl group, a cyclodecanediyl group, a
norbornanediyl group and an adamantanediyl group;
[0212] cycloalkenediyl groups such as a cyclopropenediyl group, a
cyclopentenediyl group, a cyclohexenediyl group and a
norbornenediyl group; and the like.
[0213] The monovalent chain hydrocarbon group having 1 to 20 carbon
atoms and the monovalent alicyclic hydrocarbon group having 3 to 20
carbon atoms which may be represented by R.sup.A and R.sup.B are
exemplified by groups obtained by incorporating one hydrogen atom
into those exemplified as the divalent group which may be
represented by L, and the like. R.sup.A and R.sup.B preferably
represent a hydrogen atom or a monovalent chain hydrocarbon group,
more preferably a hydrogen atom or an alkyl group, and still more
preferably a hydrogen atom or a methyl group.
[0214] The aliphatic heterocyclic structure having 3 to 20 ring
atoms taken together represented by L and R.sup.A together with the
nitrogen atom to which L and R.sup.A bond is exemplified by an
azacyclopropane structure, an azacyclobutane structure, an
azacyclopentane structure, an azacyclohexane structure, an
azacyclooctane structure, an azanorbornane structure and the
like.
[0215] Examples of the group (b) include an amino group, an
aminomethyl group, a methylamino group, a methylamino methyl group,
a dimethylamino group, a dimethylamino methyl group, a diethylamino
group, a diethylaminopropyl group, a pyrrolidin-1-yl group, a
pyrrolidin-1-ylmethyl group, a piperidin-1-yl group, a
piperidin-1-ylethyl group and the like.
[0216] The position of binding of the group (a) and the group (b)
on the polymer (I-A) is not particularly limited, and the group (a)
and the group (b) may bond to any of the main chain, the side
chain, the end of the chain of the polymer (I-A) and at least two
of these. It is preferred that the group (a) bonds to the end of
the polymer (I-A). When the group (a) bonds to the polymer (I-A),
the effects by the pattern-forming method can be exerted while the
amount of incorporation of the group (a) into the polymer (I-A) is
decreased. In addition, the group (a) may be conveniently
introduced to the end of the polymer (I-A) by permitting
polymerization using a radical polymerization initiator having the
group (a).
[0217] Solvent (i)
[0218] The composition (I-A) typically contains the solvent (i).
The solvent (i) is exemplified by solvents similar to those
exemplified as the organic solvent for use in the
prepattern-forming step, and the like.
[0219] Other Components
[0220] Other component which may be contained in the composition
(I-A) is exemplified by an acid incrementor, a surfactant and the
like.
[0221] Acid Incrementor
[0222] The acid incrementor is a component that is stable in the
absence of an acid, but is degraded in the presence of an acid due
to a catalytic reaction of the acid to produce a protonic acid, and
then the protonic acid can be incrementally produced as the
degradation reaction is accelerated along with the increase in the
amount of the protonic acid produced. When the acid incrementor is
contained in the composition (I-A), a larger amount of acid can be
produced in the insolubilizing or desolubilizing step described
later as compared with, for example, the acid and the like diffused
from the prepattern into the resin layer. As a result, the adjacent
regions of the resin layer to the prepattern can be more
effectively insolubilized or desolubilized. The acid incrementor
may be contained in the form of a compound as as described later
(hereinafter, may be also referred to as "acid increment agent", as
appropriate), in the form incorporated into the polymer as a part
thereof, or n both of these forms.
[0223] With regard to the strength of the generated acid in order
to cause the degradation of the acid incrementor by a catalytic
action of the acid generated, the acid dissociation constant (pKa)
is preferably no greater than 3, and more preferably no greater
than 2. When a weak acid having a pKa of greater than 3 is
generated, the degradation of the acid incrementor tends to be less
likely to proceed. The generated acid is preferably an organic
sulfonic acid, and more preferably methanesulfonic acid,
ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid,
pentanesulfonic acid, hexanesulfonic acid, heptanesulfonic acid,
octanesulfonic acid, cyclohexanesulfonic acid, camphorsulfonic
acid, trifluoromethanesulfonic acid, 2,2,2-trifluoroethanesulfonic
acid, benzenesulfonic acid, p-toluenesulfonic acid,
p-bromobenzenesulfonic acid, p-nitrobenzenesulfonic acid,
2-thiophenesulfonic acid, 1-naphthalenesulfonic acid and
2-naphthalenesulfonic acid.
[0224] It is preferred that the acid incrementor is a compound in
which a sulfonate group represented by the following formula (E) is
bonded, directly or via a divalent organic group, to the carbon
atom that is forming a carbocyclic skeleton.
--OSO.sub.2--R.sup.a (E)
[0225] In the above formula (E), R.sup.a represents a monovalent
organic group.
[0226] The monovalent organic group represented by R.sup.a is
exemplified by a chain organic group, an organic group having an
alicyclic structure, an organic group having an aromatic ring
structure, an organic group having a heterocyclic structure, and
the like.
[0227] The chain organic group is an organic group having carbon
atoms of preferably 1 to 12, and more preferably 1 to 8. Examples
of the chain organic group include: unsubstituted alkyl groups such
as a methyl group, an ethyl group, a propyl group, a butyl group, a
pentyl group and a hexyl group; unsubstituted acyl groups such as a
formyl group, an acetyl group, a propionyl group and a butyryl
group; unsubstituted alkenyl groups such as a vinyl group and an
allyl group; unsubstituted alkenylcarbonyl groups such as a
vinylcarbonyl group and an allyl carbonyl group; substituted forms
of these groups; and the like.
[0228] Examples of the organic group having an alicyclic structure
include: alicyclic hydrocarbon groups such as a cyclohexyl group, a
cyclooctyl group, a bicyclohydrocarbon group and a
tricyclohydrocarbon group; substituted forms of the same; and the
like.
[0229] Examples of the organic group having an aromatic ring
structure include aryl groups such as a phenyl group and a naphthyl
group; aralkyl groups such as a benzyl group, a phenethyl group and
a naphthylmethyl; substituted forms of the same; and the like.
[0230] Examples of the organic group having a heterocyclic
structure include heterocyclic groups derived from a heterocyclic
compound, and substituted forms of the same such as e.g.:
5-membered ring compound having one hetero atom such as furan,
pyrrole, benzofuran, indole and carbazole, and condensed ring
compounds of the same; 5-membered ring compound having two hetero
atoms such as oxazole and pyrazole, and condensed ring compounds of
the same; 6-membered ring compounds having one hetero atom such as
pyran, pyrone, coumarin, pyridine, quinoline, isoquinoline and
acridine, and condensed ring compounds of the same; 6-membered ring
compounds having two hetero atoms such as pyridazine, pyrimidine,
pyrazine and phthalzine, and condensed ring compounds of the same;
and the like.
[0231] The substituent that gives the substituted form of the group
is exemplified by halogen atoms such as a fluorine atom, a chlorine
atom, a bromine atom and an iodine atom, an oxyhydrocarbon group,
an amino group, a substituted amino group and the like.
[0232] The compound having a sulfonate group represented by the
above formula (E) is exemplified by a compound represented by the
following formula, and the like.
##STR00017##
[0233] In the above formula, R.sup.a is as defined in the above
formula (E); R.sup.b represents a hydrogen atom, a chain monovalent
organic group, a monovalent organic group having an alicyclic
structure or a monovalent organic group having an aromatic ring
structure; R.sup.c represents a chain monovalent organic group, a
monovalent organic group having an alicyclic structure, or a
monovalent organic group having an aromatic ring structure; and L
represents a single bond or a divalent organic group.
[0234] The chain organic group, the organic group having an
alicyclic structure and the organic group having an aromatic ring
structure represented by R.sup.b and R.sup.c are exemplified by
groups similar to those exemplified as each group represented by
R.sup.a in the above formula (E), and the like.
[0235] Of these, R.sup.b represents preferably the chain organic
group, the organic group having an alicyclic structure and the
organic group having an aromatic ring structure.
[0236] As the chain monovalent organic group represented by
R.sup.c, an alkyl group which may have a fluorine atom, and a
cycloalkyl group which may have a fluorine atom are preferred.
Examples of these groups include a methyl group, an ethyl group, a
n-propyl group, an isopropyl group, a n-butyl group, a t-butyl
group, a n-pentyl group, a cyclopentyl group, a n-hexyl group, a
cyclohexyl group, a n-octyl group, a trifluoromethyl group, a
pentafluoroethyl group, a perfluorobutyl group, a perfluoro-t-butyl
group, a perfluoropentyl group, a perfluorocyclopentyl group, a
perfluorohexyl group, a perfluorocyclohexyl group, a perfluorooctyl
group, and the like.
[0237] As the divalent organic group represented by L, a group
represented by the following formula group is preferred.
##STR00018##
[0238] The acid increment agent is exemplified by compounds
represented by the following formulae, and the like.
##STR00019## ##STR00020##
[0239] In a case where the acid incrementor is the acid increment
agent, the content of the acid incrementor in the composition (I-A)
with respect to 100 parts by mass of the polymer (I) is, in light
of effective refining of the pattern by the pattern-forming method,
preferably no less than 0 parts by mass, and more preferably no
less than 1 part by mass. On the other hand, the content of the
acid incrementor in the composition (I-A) is preferably no greater
than 20 parts by mass, and more preferably no greater than 10 parts
by mass.
Composition (I-B)
[0240] The composition (I-B) contains the polymer (I) having a
solubility in the organic solvent to be decreased by an action of
an acid, and a basic compound (hereinafter, may be also referred to
as "(q) basic compound" or "basic compound (q)"). Similarly to the
composition (I-A), the composition (I-B) preferably contains the
solvent (i), and also may contain other component(s) such as the
acid incrementor, in addition to these components. The polymer (I)
is as already described above.
(q) Basic Compound
[0241] The basic compound (q) is not particularly limited as long
as it is basic, and is preferably, for example, at least one
selected from the group consisting of a compound represented by the
following formula (X) (hereinafter, may be also referred to as
"compound (X)") and a compound represented by the following formula
(Y) (hereinafter, may be also referred to as "compound (Y)").
##STR00021##
[0242] In the above formula (X), X.sup.+ represents a monovalent
onium cation; and Y.sup.- represents a monovalent carboxylate anion
or a monovalent sulfonamide anion.
[0243] In the above formula (Y), R.sup.X, R.sup.Y and R.sup.Z each
independently represent an unsubstituted, hydroxy-substituted or
amino-substituted monovalent chain hydrocarbon group having 1 to 20
carbon atoms or an unsubstituted, hydroxy-substituted or
amino-substituted monovalent alicyclic hydrocarbon group having 3
to 20 carbon atoms, or at least two of R.sup.X, R.sup.Y and R.sup.Z
taken together represent an aliphatic heterocyclic structure having
3 to 20 ring atoms together with the nitrogen atom to which the at
least two groups bond and the rest of R.sup.X, R.sup.Y and R.sup.Z
represents an unsubstituted, hydroxy-substituted or
amino-substituted monovalent chain hydrocarbon group having 1 to 20
carbon atoms or an unsubstituted, hydroxy-substituted or
amino-substituted monovalent alicyclic hydrocarbon group having 3
to 20 carbon atoms.
[0244] The monovalent onium cation represented by X.sup.+ is
exemplified by a sulfonium cation, an iodonium cation, an ammonium
cation, an oxonium cation, and the like.
[0245] The monovalent carboxylate anion which may be represented by
Y.sup.- is exemplified by a salicylate anion, and the like.
[0246] The monovalent sulfonamide anion which may be represented by
Y.sup.- is exemplified by a trifluoromethyl sulfonamide ion, and
the like.
[0247] The unsubstituted monovalent chain hydrocarbon group having
1 to 20 carbon atoms and unsubstituted monovalent alicyclic
hydrocarbon group having 3 to 20 carbon atoms which may be
represented by R.sup.X, R.sup.Y and R.sup.Z is exemplified by
groups similar to those exemplified as R.sup.p1, R.sup.p2 and
R.sup.p3 in the above formula (i), respectively, and the like.
[0248] Examples of the hydroxy-substituted monovalent chain
hydrocarbon group having 1 to 20 carbon atoms which may be
represented by R.sup.X, R.sup.Y and R.sup.Z include:
[0249] hydroxyalkyl groups such as a hydroxymethyl group, a
hydroxyethyl group, a hydroxypropyl group and a hydroxybutyl
group;
[0250] hydroxyalkenyl groups such as a hydroxyethenyl group and a
hydroxypropenyl group; and the like.
[0251] Examples of the hydroxy-substituted monovalent alicyclic
hydrocarbon group having 3 to 20 carbon atoms which may be
represented by R.sup.X, R.sup.Y and R.sup.Z include:
[0252] hydroxycycloalkyl groups such as a hydroxycyclopentyl group,
a hydroxycyclohexyl group, a hydroxynorbornyl group and a
hydroxyadamantyl group;
[0253] hydroxycycloalkenyl groups such as a hydroxycyclopentenyl
group and a hydroxycyclohexenyl group; and the like.
[0254] Examples of the amino-substituted monovalent chain
hydrocarbon group having 1 to 20 carbon atoms which may be
represented by R.sup.X, R.sup.Y and R.sup.Z include:
[0255] aminoalkyl groups such as an aminomethyl group, an
aminoethyl group, an aminopropyl group and an aminobutyl group;
[0256] aminoalkenyl groups such as an aminoethenyl group and an
aminopropenyl group; and the like.
[0257] Examples of the amino-substituted monovalent alicyclic
hydrocarbon group having 3 to 20 carbon atoms which may be
represented by R.sup.X, R.sup.Y and R.sup.Z include:
[0258] aminocycloalkyl groups such as an aminocyclopentyl group, an
aminocyclohexyl group, an aminonorbornyl group and an
aminoadamantyl group;
[0259] aminocycloalkenyl groups such as an aminocyclopentenyl group
and an aminocyclohexenyl group; and the like.
[0260] Examples of the aliphatic heterocyclic structure having 3 to
20 ring atoms which may be taken together represented by at least
two of R.sup.X, R.sup.Y and R.sup.Z together with the nitrogen atom
to which the at least two groups bond include:
[0261] azacycloalkane structures such as an azacyclopropane
structure, an azacyclobutane structure, an azacyclopentane
structure, an azacyclohexane structure, an azacyclooctane
structure, an azacyclodecane structure, an azanorbornane structure
and an azaadamantane structure;
[0262] azaoxacycloalkane structures such as an azaoxacyclopentane
structure, an azaoxacyclohexane structure, an azaoxacyclooctane
structure and an azaoxanorbornane structure;
[0263] diazacycloalkane structures such as a diazacyclopentane
structure, a diazacyclohexane structure, a diazacyclooctane
structure, a diazacyclodecane structure, a diazanorbornane
structure and a diazabicyclo[2.2.2]octane structure; and the
like.
[0264] Examples of the compound (X) include:
[0265] onium carboxylate compounds such as triphenylsulfonium
salicylate, tetra-n-octylammonium salicylate, triphenylsulfonium
acetate, triphenylsulfonium adamantyloxalate and
tetra-n-oetylammonium adamantyloxalate;
[0266] onium sulfonamide compounds such as triphenylsulfonium
n-butyltrifluoromethylsulfonamide, tetra-n-octylammonium
n-butyltrifluoromethylsulfonamide, triphenylsulfonium acesulfame
(triphenylsulfonium 6-methyl-2.2-dioxo-oxathiazine-4-olate) and
tetra-n-octylammonium acesulfame (tetra-n-octylammonium
6-methyl-2.2-dioxo-oxathiazine-4-olate); and the like.
[0267] Example of the Compound (Y) include:
[0268] monoamine compounds such as tri-n-pentylamine,
tri-n-octylamine and tricyclohexylamine;
[0269] diamine compounds such as diazabicyclo[2.2.2]octane and
N,N-dimethylethyl enediamine;
[0270] hydroxy-substituted amine compounds such as
4-hydroxy-1,2,2,6,6-pentamethylpiperidine and triethanolamine; and
the like.
[0271] The lower limit of the content of the basic compound (q)
with respect to 100 parts by mass of the polymer (I) is preferably
0.1 parts by mass, more preferably 0.5 parts by mass, still more
preferably 1 part by mass, and particularly preferably 3 parts by
mass. The upper limit of the content of the basic compound (q) with
respect to 100 parts by mass of the polymer (I) is preferably 30
parts by mass, more preferably 20 parts by mass, still more
preferably 15 parts by mass, and particularly preferably 12 parts
by mass. When the content of the basic compound (q) falls within
the above range, the shape of the pattern obtained can be even more
favorable.
[0272] In a case where the polymer constituting the prepattern has
the acid-labile group, it is preferred that the basic group and the
basic compound (q) have their basicity greater than the basicity of
the conjugated base of the acidic group generated by dissociation
of the acid-labile group. When the basic group and the basic
compound having such a property are used, a pattern having a more
favorable shape can be formed according to the pattern-forming
method.
Insolubilizing or Desolubilizing Step
[0273] In this step, adjacent regions to the prepattern of the
resin layer are insolubilized or desolubilized in the organic
solvent, without being accompanied by an increase in the molecular
weight by heating the prepattern and the resin layer. According to
this step, in adjacent regions to the prepattern of the resin layer
3, adjacent regions 4 that are insoluble or hardly soluble in the
organic solvent are formed as shown in FIG. 1C. The phrase "without
being accompanied by an increase in the molecular weight" as
referred to means that owing to e.g., the absence of generation of
a novel covalent bond between the polymer constituting the
prepattern and the polymer constituting the resin layer, each
molecular weight of these polymers does not substantially increase.
In this step, it is presumed that e.g., heating of the prepattern
and the resin layer would result in a diffusion of the acid, etc.,
contained in the prepattern, for example, into the adjacent regions
to the prepattern of the resin layer, and then the polymer that is
present in the adjacent regions would be insolubilized or
desolubilized in the organic solvent due to the action of the
acid.
[0274] The heating procedure is exemplified by heating on a hot
plate, and the like. The heating temperature is preferably no less
than 50.degree. C. and no greater than 250.degree. C. The heating
time period is preferably no less than 10 sec and no greater than
10 min. The heating atmosphere may be either in the air, or in an
inert gas such as nitrogen or argon.
Removing Step
[0275] In this step, regions other than the adjacent regions of the
resin layer are removed with the organic solvent. Accordingly, a
refined pattern can be obtained as shown in FIG. 1D.
[0276] The organic solvent for use in the removing is not
particularly limited as long as it does not dissolve the prepattern
and the adjacent regions, but dissolves the composition (I), and
for example, one, or two or more types of the organic solvent
exemplified in connection with the prepattern-forming step may be
used. Also, an organic solvent that is the same as the solvent
contained in the composition (I) may be used.
Rinsing Step
[0277] In this step, rinsing is carried out with an organic solvent
that is different from the organic solvent used in the removing
step. The organic solvent used in this step is not particularly
limited as long as it differs from the organic solvent used in the
removing step. For example, one, or two or more types of the
organic solvents among those exemplified in connection with the
prepattern-forming step may be used. Of these organic solvents, in
light of making the obtained shape of the pattern more favorable,
the organic solvent that is less polar than the organic solvent
used in the removing step may be preferably used.
[0278] According to the pattern-forming method, a resist pattern
having a fine and favorable shape can be formed by a convenient
method through carrying out the steps as in the foregoing.
Pattern-Forming Method (a)
[0279] The pattern-forming method (a) is also one suitable
embodiment of the present invention.
[0280] The pattern-forming method (a) includes prepattern-forming
step, the contacting step, the resin layer-forming step, the
insolubilizing or desolubilizing step, and the removing step,
wherein the resin layer is formed from the composition (I)
containing the polymer (I), and the polymer (I) has an Mw of no
less than 13,000 and no greater than 150,000.
[0281] According to the pattern-forming method (a), a resist
pattern having a fine and favorable shape can be formed with the
convenient method, substantially irrespective of the pattern type,
through the use of the composition containing the polymer having
the Mw falling within the above specified range, and the contacting
step of bringing into contact with at least lateral faces of the
prepattern, the composition which contains the basic compound and
the organic solvent, and which does not contain the polymer having
a solubility in an organic solvent to be decreased by an action of
an acid. This advantage is presumed to result from, for example,
adhesion of the basic compound to the prepattern by bringing the
composition into contact with the at least lateral faces of the
prepattern, followed by formation of regions including anionic
groups such as a carboxylate group in adjacent regions formed in
subsequent resin layer-forming step and insolubilizing or
desolubilizing step, wherein the anionic groups are derived from
the acidic groups such as the carboxy group constituting the
adjacent regions due to the basic compound, thereby leading to an
increase of the extent of the desolubilization of the adjacent
regions in the organic solvent used in the removing step. In
addition, it is believed that the pattern having a finer and more
favorable shape can be formed due to the Mw of the polymer (I)
falling within the above specified range.
[0282] Each step and the polymer (I) of the pattern-forming method
(a) are as described herein in connection with the pattern-forming
method above.
Composition for Resist Pattern-Refinement
[0283] The mode of the composition for resist pattern-refinement
may involve the following compositions (A) to (C):
[0284] composition (A): containing the polymer having a basic group
and having a solubility in an organic solvent to be decreased by an
action of an acid;
[0285] composition (B): containing the polymer having a solubility
in an organic solvent to be decreased by an action of an acid, and
the basic compound; and
[0286] composition (C): containing the basic compound and the
organic solvent, and not containing the polymer having a solubility
in an organic solvent to be decreased by an action of an acid.
[0287] It is preferred that the polymer contained in the
composition (A) and the composition (B) has an aromatic ring. In
addition, the proportion of the structural unit having the aromatic
ring contained with respect to the total structural units is
preferably no less than 20 mol %.
[0288] The polymer contained in the composition (A) and composition
(B) preferably has an Mw of no less than 13,000 and no greater than
150,000.
[0289] The composition for resist pattern-refinement is described
herein above, i.e., the composition (A): as the composition (I-A)
that involves the feature (i) in connection with the
pattern-forming method; the composition (B): as the composition
(I-B) that involves feature (ii); and the composition (C): as the
composition (II) in connection with the pattern-forming method.
EXAMPLES
[0290] Hereinafter, the present invention is explained in detail by
way of Examples, but, the present invention is not in any way
limited to these Examples.
Synthesis of Polymer
[0291] The polymer (a) and the polymer (d) for use in the
preparation of the resist composition, and the monomer compound and
the polymerization initiator used in the synthesis of the polymer
(I) for use in the preparation of the composition for resist
pattern-refinement are shown in the following.
##STR00022## ##STR00023##
Synthesis of Polymer (a)
Synthesis Example 1: Synthesis of Polymer (A-1)
[0292] A monomer solution was prepared by dissolving 40 mol % of
the compound (M-1), 10 mol % of the compound (M-2), 40 mol % of the
compound (M-3), 10 mol % of the compound (M-4), and 5 mol % of the
compound (Z-1) as a polymerization initiator in 60 g of methyl
ethyl ketone. It is to be noted that the mol % of each monomer
compound is the proportion with respect to the total monomer
compounds, and the mol % of the polymerization initiator is the
proportion with respect to the total number of moles of the entire
monomer compounds and the polymerization initiator. In addition,
the total mass of the monomer compounds was adjusted to be 30 g.
Next, 30 g of methyl ethyl ketone was charged into a 500 mL
three-neck flask equipped with a thermometer and s dropping funnel,
and purged with nitrogen for 30 min. Thereafter, the flask was
heated to 80.degree. C. while the mixture was stirred with a
magnetic stirrer. Then, the monomer solution which had been
prepared as described above was added dropwise into the three-neck
flask over 3 hrs by using the dropping funnel. The time of the
start of the dropwise addition was regarded as the time of the
start of the polymerization reaction, and the polymerization
reaction was allowed to proceed for 6 hrs. Thereafter, the
polymerization reaction mixture was cooled to 30.degree. C. or
below, then the polymerization reaction mixture was poured into 600
g of methanol, and a precipitated white powder was filtered off.
Thus collected white powder was washed twice with each 120 g of
methanol to give a slurry state, followed by separation by
filtration, and dried at 50.degree. C. for 17 hrs to obtain a
polymer (A-1) as a white powder (product amount: 23.3 g, yield:
77.6%). The polymer (A-1) had an Mw of 6,200 and an Mw/Mn of 1.62.
In addition, the result of.sup.13C-NMR analysis indicated that the
proportions of the structural units derived from (M-1), (M-2),
(M-3) and (M-4) in the polymer (A-1) were 40.2 mol %, 9.0 mol %,
41.1 mol % and 9.7 mol %, respectively.
Synthesis of Polymer (d)
Synthesis Example 2: Synthesis of Polymer (D-1)
[0293] A monomer solution was prepared by dissolving 70 mol % of
the compound (M-5), 30 mol % of the compound (M-6), and 8 mol % of
the compound (Z-2) as a polymerization initiator in 100 g of methyl
ethyl ketone. It is to be noted that the mol % of each monomer
compound is the proportion with respect to the total monomer
compounds, and the mol % of the polymerization initiator is the
proportion with respect to the total number of moles of the entire
monomer compounds and the polymerization initiator. In addition,
the total mass of the monomer compounds was adjusted to be 50 g.
Next, a 500 mL three-neck flask containing 100 g of methyl ethyl
ketone was purged with nitrogen for 30 min, then heated to
80.degree. C. with stirring, and the monomer solution which had
been prepared as described above was added dropwise over 3 hrs
using a dropping funnel. The time of the start of the dropwise
addition was regarded as the time of the start of the
polymerization reaction, and the polymerization reaction was
allowed to proceed for 6 hrs. After the completion of the
polymerization reaction, the polymerization reaction mixture was
water-cooled to 30.degree. C. or below. After washing the
polymerization reaction mixture with 825 g of a mixed solution of
methanol/methyl ethyl ketone/ hexane=2/1/8 (mass ratio), the
solvent was substituted with propylene glycol monomethyl ether
acetate to obtain a solution containing a polymer (D-1) (amount of
obtained polymer: 38.0 g, yield: 76.0%). The polymer (D-1) had an
Mw of 7,000, and an Mw/Mn of 1.40. In addition, the result
of.sup.13C-NMR analysis indicated that the proportions of the
structural units derived from (M-5) and (M-6) in the polymer (D-1)
were 70.2 mol % and 29.8 mol %, respectively.
TABLE-US-00001 TABLE 1 Monomer that gives structural unit Monomer
that gives structural units (I) (II) to (IV) Polymerization
proportion of proportion of initiator amount structural amount
structural amount Yield Polymer type (mol %) unit (mol %) type (mol
%) unit (mol %) type (mol %) (%) Mw Mw/Mn Synthesis A-1 M-1 40 40.2
M-3 40 41.1 Z-1 5 77.6 6,200 1.62 Example 1 M-2 10 9.0 M-4 10 9.7
Synthesis D-1 M-5 70 70.2 M-6 30 29.8 Z-2 8 76.0 7,000 1.40 Example
2
Synthesis of Polymer (I)
Synthesis Examples 3 to 10: Synthesis of Polymers (I-1) to
(I-8)
[0294] Polymers (I-1) to (I-8) were each synthesized by a similar
operation to that of Synthesis Example 1 except that the type and
the amount of the monomer compound and the polymerization initiator
used were as shown in Table 2 below. The Mw, the Mw/Mn and the
yield of each polymer, and the proportion of each structural unit
contained in each polymer are shown together in Table 2. The symbol
"-" in Table 2 indicates that the corresponding monomer was not
used.
TABLE-US-00002 TABLE 2 Monomer 1 Monomer 2 Monomer 3 propor-
propor- propor- Polymerization tion of tion of tion of initiator
structur- structur- structur- using (I) amount al unit amount al
unit amount al unit amount Yield Polymer type (mol %) (mol %) type
(mol %) (mol %) type (mol %) (mol %) type (mol %) (%) Mw Mw/Mn
Synthesis I-1 M-1 65 63.9 M-3 35 36.1 -- -- -- Z-1 2 82.3 14,000
2.33 Example 3 Synthesis I-2 M-1 65 64.5 M-3 35 35.5 -- -- -- Z-1 5
78.0 6,300 1.82 Example 4 Synthesis I-3 M-1 10 10.6 M-7 60 61.9 M-8
30 27.5 Z-1 2 81.8 13,500 2.10 Example 5 Synthesis I-4 M-1 50 51.1
M-2 20 18.4 M-9 30 30.5 Z-1 1.5 83.5 22,000 2.68 Example 6
Synthesis I-5 M-10 10 12.6 M-11 60 58.5 M-3 30 28.9 Z-1 1 78.6
30,000 2.59 Example 7 Synthesis I-6 M-12 70 69.7 M-3 30 30.3 -- --
-- Z-3 2 75.7 19,200 2.35 Example 8 Synthesis I-7 M-12 40 42.7 M-13
30 27.2 M-14 30 30.1 Z-1 1.5 77.2 25,000 2.55 Example 9 Synthesis
I-8 M-10 10 8.8 M-15 60 58.3 M-3 30 32.9 Z-1 2 80.8 14,500 2.13
Example 10
Preparation of Resist Composition
[0295] The acid generating agent (b), the solvent (c) and the acid
diffusion control agent (e) used in the preparation of the resist
composition, other than the polymer (a) and the polymer (d), are
shown below.
(b) Acid Generating Agent
[0296] B-1 : triphenylsulfonium
1,1-difluoro-24(3-hydroxyadamantan-1-yl)methoxy)-2-oxoethanesulfonate
(a compound represented by the following formula (B-1))
##STR00024##
(c) Solvent
[0297] C-1: propylene glycol monomethyl ether acetate
[0298] C-2: cyclohexanone
[0299] C-3: .gamma.-butyrolactone
(e) Acid Diffusion Control Agent
[0300] E-1: tert-pentyl 4-hydroxypiperidine- l -carboxylate (a
compound represented by the following formula (E-1))
##STR00025##
Preparation Example 1: Preparation of Resist Composition (J-1)
[0301] A resist composition (J-1) was prepared by mixing 100 parts
by mass of the polymer (A-1) as the polymer (a), 7.8 parts by mass
of the acid generating agent (B-1) as the acid generating agent
(b), 2,510 parts by mass of the solvent (C-1), 1,075 parts by mass
of the solvent (C-2) and 30 parts by mass of the solvent (C-3) as
the solvent (c), 3 parts by mass of the polymer (D-1) as the
polymer (d), and 0.8 parts by mass of the acid diffusion control
agent (E-1) as the acid diffusion control agent (e).
TABLE-US-00003 TABLE 3 (b) Acid generating (e) Acid diffusion (a)
Polymer agent (c) Solvent (d) Polymer control agent amount amount
amount amount amount blended blended blended blended blended Resist
(parts (parts (parts (parts (parts composition type by mass) type
by mass) type by mass) type by mass) type by mass) Preparation J-1
A-1 100 B-1 7.8 C-1/C-2/C-3 2,510/1,075/30 D-1 3 E-1 0.8 Example
1
Preparation of Composition for Resist Pattern-Refinement
[0302] The basic compound (q) and the solvent (p) used in the
preparation of the composition for resist pattern-refinement, other
than the polymer (I), are shown below.
(q) Basic Compound
[0303] Q-1: triphenylsulfonium n-butyltrifluoromethylsulfonamide (a
compound represented by the following formula (Q-1))
[0304] Q-2: triphenylsulfonium salicylate (a compound represented
by the following formula (Q-2))
[0305] Q-3: trioctylamine (a compound represented by the following
formula (Q-3))
[0306] Q-4: 4-hydroxy-1,2,2,6,6-pentamethylpiperidine (a compound
represented by the following formula (Q-4))
[0307] Q-5: diazabicyclo[2.2.2]octane (a compound represented by
the following formula (Q-5))
[0308] Q-6: tetra-n-octylammonium salicylate (a compound
represented by the following formula (Q-6))
##STR00026##
(p) Solvent
[0309] P-1: propylene glycol monomethyl ether acetate
[0310] P-2: cyclohexanone
[0311] P-3: butyl acetate (nBA)
[0312] P-4: 2-heptanone (MAK)
Preparation Example 2: Preparation of Composition for Resist
Pattern-Refinement (S-1)
[0313] A composition for resist pattern-refinement (S-1) was
prepared by mixing 100 parts by mass of (I-1) as the polymer (I), 8
parts by mass of (Q-1) as the basic compound (q), and 2,084 parts
by mass of (P-1) and 894 parts by mass of (P-2) as the solvent
(p).
Preparation Examples 3 to 13: Preparation of Compositions for
Resist Pattern-Refinement (S-2) to (S-10)and (S-12) and (S-13)
[0314] Compositions for pattern-refinement (S-2) to (S-10)and
(S-12) and (S-13) were each prepared by a similar operation to that
of Preparation Example 1 except that the type and the amount of
each component blended were as shown in Table 4 below.
TABLE-US-00004 TABLE 4 (I) Polymer (q) Basic compound (p) Solvent
Composition for amount blended amount blended amount blended
pattern-refinement type (parts by mass) type (parts by mass) type
(parts by mass) Preparation Example 2 S-1 I-1 100 Q-1 8 P-1/P-2
2,084/894 Preparation Example 3 S-2 I-2 100 Q-2 8 P-3 3,892
Preparation Example 4 S-3 I-3 100 Q-2 12 P-3 4,036 Preparation
Example 5 S-4 I-4 100 Q-3 5 P-1 2,520 Preparation Example 6 S-5 I-5
100 -- -- P-3 3,604 Preparation Example 7 S-6 I-6 100 -- -- P-3
3,604 Preparation Example 8 S-7 I-7 100 Q-4 5 P-1/P-2 2,026/869
Preparation Example 9 S-8 I-8 100 Q-1 5 P-4 3,784 Preparation
Example 10 S-9 I-1 100 Q-1 2 P-1/P-2 1,968/844 Preparation Example
11 S-10 I-1 100 -- -- P-1/P-2 1,930/827 Preparation Example 12 S-12
I-1 100 Q-5 5 P-1/P-2 2,026/869 Preparation Example 13 S-13 I-3 100
Q-6 12 P-3 4,036
Formation of Pattern
Example 1: Formation of Prepattern
[0315] An underlayer antireflective film having a thickness of 105
nm was provided on a 12-inch silicon wafer by spin-coating an
antireflective film-forming agent ("ARC66" available from Nissan
Chemical Industries, Ltd.) with a coater/developer ("CLEAN TRACK
Lithius Pro i" available from Tokyo Electron Limited), followed by
baking at 205.degree. C. for 60 sec. On the substrate provided with
the underlayer antireflective film, the resist composition (J-1)
prepared as described above was spin-coated with a coater/
developer ("CLEAN TRACK ACT12" available from Tokyo Electron
Limited), followed by soft baking (SB) at 80.degree. C. for 60 sec
and then cooling at 23.degree. C. for 30 sec to form a resist film
having a film thickness of 70 nm.
[0316] Next, a reduced projection exposure was carried out through
a hole pattern mask by using ArF Immersion Scanner ("NSR-S610C"
available from Precision Equipment Company, Nikon Corporation),
under optical conditions involving a numerical aperture (NA) of
1.3, with cloth pole such that a pattern of 50 nm hole/ 125 nm
pitch and a pattern of 50 nm hole/1,000 nm pitch were formed. After
the exposure, post exposure baking (PEB) was carried out on a hot
plate of the "CLEAN TRACK Lithius Pro i" at 95.degree. C. for 60
sec, followed by cooling at 23.degree. C. for 30 sec.
[0317] Then, a puddle development was carried out by using n-butyl
acetate as a developer solution for 25 sec, and subsequently, a
rinse treatment was carried out by using 4-methyl-2-pentanol as a
rinse agent for 7 sec. Thereafter, spin-drying at 2,000 rpm for 15
sec resulted in formation of 50 nm hole/ 125 nm pitch and 50 nm
hole/1,000 nm pitch prepatterns.
[0318] Pattern Slimming
[0319] The composition for resist pattern-refinement (S-1) was
spin-coated on the prepattern by using the coater/ developer
("CLEAN TRACK ACT12" s available from Tokyo Electron Limited),
followed by heating at 120.degree. C. for 60 sec, and then cooling
at 23.degree. C. for 30 sec resulted in formation of a resin layer
on the surface of the prepattern.
[0320] Then, regions other than the adjacent regions were removed
by a puddle procedure using n-butyl acetate as an organic solvent
for 25 sec, and subsequently, rinsed with 4-methyl-2-pentanol
(MIBC) as a rinse agent for 7 sec. Thereafter, spin-drying was
carried out at 2,000 rpm for 15 sec.
Examples 2 to 8, 11 and 12, and Comparative Example 1
[0321] Patterns were formed by a similar operation to that in
Example 1 except that the composition for resist pattern-refinement
employed, the heating temperature and time period were as shown in
Table 5 below. In Table 5, "-" indicates that the contacting step
was not carried out.
Example 9
[0322] Contacting Step
[0323] On a prepattern obtained in a similar manner to Example 1, a
0.3% by mass solution in MIBC of (Q-4) as the basic compound (q)
was spin-coated by using "CLEAN TRACK ACT12".
[0324] Pattern Slimming
[0325] A similar operation to that of Example 1 was carried out on
the prepattern after subjecting to the contacting step was except
that (S-9) was used as the composition for resist
pattern-refinement to foul' a pattern.
Example 10
[0326] A pattern was &limed in a similar manner to Example 9
except that (S-10) was used as the composition for resist
pattern-refinement employed.
Comparative Example 2
[0327] Pattern Slimming
[0328] On a prepattern obtained in a similar manner to Example 1, a
composition (S-11, a crosslinking layer-forming material (B5)
disclosed in Example 10 of Japanese Patent No. 4558064) prepared by
mixing 5.5 parts by mass of a pol.gamma.-p-hydroxystyrene resin
("VP8000" available from Nippon Soda Co., Ltd.), 3 parts by mass of
a hexamethoxymethylmelamine resin ("Cyme1300" available from
Kyoeisha Chemical Co., Ltd.) and 190 parts by mass of 1-butanol was
spin-coated by using "CLEAN TRACK ACT12", and heated at 155.degree.
C. for 90 sec, followed by cooling at 23.degree. C. for 30 sec.
Next, a puddle procedure was carried out on "CLEAN TRACK Lithius
Pro i" with a 2.38% by mass aqueous TMAH solution for 60 sec, and
subsequently ultra pure water was used as a rinse agent to execute
a rinse treatment, followed by baking at 90.degree. C. for 90 sec
to form a pattern.
Evaluations
[0329] The amount of dimension reduction of a hole pattern, and the
pattern type dependency were evaluated on the pattern obtained as
described above, according to the following method. Thus obtained
results of the evaluations are shown together in Table 5 below.
Amount of Dimension Reduction
[0330] A hole pattern of 125 nm pitch and 1,000 nm pitch formed as
described above was observed using a scanning electron microscope
("CG4000" available from Hitachi High-Technologies Corporation) to
determine the hole size of the prepattern and the hole size of the
pattern after subjecting to the pattern slimming step, and the
difference therebetween was calculated to define the amount of
dimension reduction (nm).
Pattern Type Dependency
[0331] In the evaluation of the amount of dimension reduction, the
difference between the amount of dimension reduction for 125 nm
pitch hole, and the amount of dimension reduction for 1,000 nm
pitch hole was determined as the pattern type dependency (nm). The
pattern type dependency was evaluated to be: "favorable" when the
difference was less than 5 nm; and "unfavorable" when the
difference was no less than 5 nm.
Etching Resistance
[0332] The etching rate of the film formed from each composition
for resist pattern-refinement was determined by using a dry etching
apparatus ("Telius SCCM" available from Tokyo Electron Limited),
and the evaluation was made by comparing with the etching rate of
the film formed from the resist composition employed for the
prepattern to be: "A" when etching rate of the film formed from the
composition for resist pattern-refinement was less; "B" when the
etching rates were equivalent; and "C" when etching rate of the
film formed from the composition for resist pattern-refinement was
grater.
TABLE-US-00005 TABLE 5 Composition for Baking temperature Amount of
dimension reduction (nm) resist pattern- temperature time period
125 nm 1,000 nm Pattern type Etching refinement (.degree. C.) (sec)
Contacting step pitch pitch dependency resistance Example 1 S-1 120
60 -- 18 20 favorable B Example 2 S-2 140 60 -- 13 14 favorable B
Example 3 S-3 100 60 -- 22 21 favorable B Example 4 S-4 80 60 -- 18
18 favorable A Example 5 S-5 150 60 -- 20 19 favorable B Example 6
S-6 90 60 -- 15 16 favorable B Example 7 S-7 100 60 -- 16 16
favorable A Example 8 S-8 180 60 -- 25 26 favorable A Example 9 S-9
120 60 basic compound (Q-4) 23 24 favorable B 0.3% by mass MIBC
solution Example 10 S-10 120 60 basic compound (Q-4) 18 19
favorable B 0.3% by mass MIBC solution Example 11 S-12 120 60 -- 17
19 favorable B Example 12 S-13 100 60 -- 20 18 favorable B
Comparative S-10 120 60 -- pattern absent Example 1 Comparative
S-11 155 90 -- 9 28 unfavorable B Example 2 90 90
[0333] As is clear from the results shown in Table 5, less pattern
type dependency of the amount of dimension reduction was exhibited
according to the pattern-forming method of Examples, as compared
with a conventional pattern-forming method demonstrated by
Comparative Example 2. Therefore, the pattern-forming method of
Examples can be suitably used also in formation of a pattern layout
in which various patterns are present admixed. In addition, in
cases where: the composition for resist pattern-refinement did not
contain the basic group or basic compound; and the step of bringing
the composition (II) containing the basic compound and organic
solvent and not containing the polymer having a solubility in an
organic solvent to be decreased by an action of an acid was not
carried out, as in Comparative Example 1, impairment of the amount
of dimension reduction, and deterioration of the pattern occurred
which would result from dissolution of the prepattern. According to
the pattern-forming method of Examples of the present invention,
the acidic group such as a carboxy group included in the prepattern
was converted into an ionic group such as a carboxylate group due
to the basicity of the composition for resist pattern-refinement,
and thus the adjacent regions became more hardly soluble in organic
solvents, thereby enabling the amount of dimension reduction suited
for fine pattern formation to be attained. Moreover, the polymer of
composition for resist pattern-refinement having a structural unit
that includes an aromatic ring, further enhances the etching
resistance of the pattern.
[0334] According to the pattern-forming methods and the
compositions for resist pattern-refinement of the embodiments of
the present invention, a resist pattern having a fine and favorable
shape can be formed substantially irrespective of the pattern type
by a convenient process. Therefore, these can be suitably used for
pattern formation in the fields of semiconductor processing and the
like in which further progress of miniaturization is expected in
the future.
[0335] Obviously, numerous modifications and variations of the
present invention are possible in light of the above teachings. It
is therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
* * * * *