U.S. patent application number 13/940119 was filed with the patent office on 2014-12-11 for resist pattern-forming method, and radiation-sensitive resin composition.
The applicant listed for this patent is JSR CORPORATION. Invention is credited to Taiichi FURUKAWA, Masafumi HORI, Koji ITO, Hiromu MIYATA, Hirokazu SAKAKIBARA.
Application Number | 20140363766 13/940119 |
Document ID | / |
Family ID | 46580524 |
Filed Date | 2014-12-11 |
United States Patent
Application |
20140363766 |
Kind Code |
A9 |
SAKAKIBARA; Hirokazu ; et
al. |
December 11, 2014 |
RESIST PATTERN-FORMING METHOD, AND RADIATION-SENSITIVE RESIN
COMPOSITION
Abstract
A resist pattern-forming method includes forming a resist
coating film using a radiation-sensitive resin composition. The
resist coating film is exposed and developed using a developer
solution containing no less than 80% by mass of an organic solvent.
The radiation-sensitive resin composition includes a polymer
component including a polymer having an acid-labile group, and a
radiation-sensitive acid generator. The polymer component includes,
in an identical polymer or different polymers, a first structural
unit having a first hydrocarbon group, and a second structural unit
having a second hydrocarbon group. The first hydrocarbon group is
an unsubstituted or substituted branched chain group, or the is
like. The second hydrocarbon group has an adamantane skeleton. A
molar ratio of the second hydrocarbon group to the first
hydrocarbon group is less than 1. A proportion of a structural unit
having a hydroxyl group in the polymer component is less than 5 mol
%.
Inventors: |
SAKAKIBARA; Hirokazu;
(Tokyo, JP) ; FURUKAWA; Taiichi; (Tokyo, JP)
; HORI; Masafumi; (Tokyo, JP) ; ITO; Koji;
(Tokyo, JP) ; MIYATA; Hiromu; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JSR CORPORATION |
Tokyo |
|
JP |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20130295506 A1 |
November 7, 2013 |
|
|
Family ID: |
46580524 |
Appl. No.: |
13/940119 |
Filed: |
July 11, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2011/079736 |
Dec 21, 2011 |
|
|
|
13940119 |
|
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Current U.S.
Class: |
430/270.1 ;
430/311 |
Current CPC
Class: |
G03F 7/38 20130101; G03F
7/0046 20130101; G03F 7/0397 20130101; G03F 7/0041 20130101; G03F
7/20 20130101; G03F 7/325 20130101; G03F 7/0045 20130101; G03F
7/2041 20130101 |
Class at
Publication: |
430/270.1 ;
430/311 |
International
Class: |
G03F 7/004 20060101
G03F007/004; G03F 7/20 20060101 G03F007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 28, 2011 |
JP |
2011-016814 |
Claims
1. A resist pattern-forming method comprising: forming a resist
coating film using a radiation-sensitive resin composition;
exposing the resist coating film; and developing the exposed resist
coating film using a developer solution containing no less than 80%
by mass of an organic solvent, the radiation-sensitive resin
composition comprising: a polymer component including a polymer
having an acid-labile group; and a radiation-sensitive acid
generator, the polymer component including, in an identical polymer
or different polymers, a first structural unit having a first
hydrocarbon group, and a second structural unit having a second
hydrocarbon group, the first hydrocarbon group being an
unsubstituted or substituted branched chain group having no greater
than 8 carbon atoms or an unsubstituted or substituted monocyclic
alicyclic group having 3 to 8 ring carbon atoms, the second
hydrocarbon group having an adamantane skeleton, a molar ratio of
the second hydrocarbon group to the first hydrocarbon group being
less than 1, and a proportion of a structural unit having a
hydroxyl group in the polymer component to a total amount of
structural units in the polymer component being less than 5 mol
%.
2. The resist pattern-forming method according to claim 1, wherein
the first structural unit is represented by a formula (1), and the
second structural unit is represented by a formula (2):
##STR00030## wherein, in the formulae (1) and (2), R and R' each
independently represent a hydrogen atom, a fluorine atom, a methyl
group or a trifluoromethyl group; R.sup.1 represents a monovalent
first hydrocarbon group; and R.sup.2 represents a monovalent second
hydrocarbon group, and R.sup.1 and R.sup.2 each independently do
not have or have a hydroxyl group, a carbonyl group, a cyano group,
a nitro group, a sulfonamide group or a combination thereof.
3. The resist pattern-forming method according to claim 2, wherein
R.sup.1 in the formula (1) represents an acid-labile group.
4. The resist pattern-forming method according to claim 2, wherein
R.sup.2 in the above formula (2) represents a group each
represented by formulae (2-1) to (2-4), an acid-labile group or a
combination thereof: ##STR00031## wherein, in the formulae (2-1) to
(2-4), R.sup.p1, R.sup.p2 and R.sup.p3 each independently represent
a hydroxyl group, a cyano group, a nitro group or a sulfonamide
group; R.sup.a1 and R.sup.a2 each independently represent a
methylene group or an alkylene group having 2 to 10 carbon atoms;
R.sup.a3 represents a single bond, a methylene group or an alkylene
group having 2 to 10 carbon atoms; q1 is an integer of 1 to 6; and
q2 and q3 are each independently an integer of 1 to 15, wherein in
a case where R.sup.p1, R.sup.p2 and R.sup.a1 are each present in a
plurality of number, a plurality of R.sup.p1s are each identical or
different, a plurality of R.sup.p2s are each identical or different
and a plurality of R.sup.a1s are each identical or different, and
wherein * denotes a binding site to an ester group in the above
formula (2).
5. The resist pattern-forming method according to claim 1, wherein
a molar ratio of the second hydrocarbon group to the first
hydrocarbon group is no less than 0.1 and no greater than 0.9.
6. The resist pattern-forming method according to claim 1, wherein
the second hydrocarbon group has a hydroxyl group, a carbonyl group
or a combination thereof.
7. The resist pattern-forming method according to claim 1, wherein
the polymer component further includes a structural unit having a
lactone group, a cyclic carbonate group or a combination
thereof.
8. The resist pattern-forming method according to claim 1, wherein
a proportion of the acid-labile group in the first hydrocarbon
group and the second hydrocarbon group to a total of the first
hydrocarbon group and the second hydrocarbon group is no less than
50 mol %.
9. The resist pattern-forming method according to claim 1, wherein
the radiation-sensitive acid generator is represented by a formula
(B-1): ##STR00032## wherein, in the formula (B-1), Rf.sup.1 and
Rf.sup.2 each independently represent a hydrogen atom, a fluorine
atom, or a fluorinated alkyl group having 1 to 4 carbon atoms; n is
an integer of 1 to 3, wherein any case in which Rf.sup.1 and
Rf.sup.2 bonded to carbon at an .alpha.-position of the sulfonate
group both represent a hydrogen atom is excluded, and in a case
where Rf.sup.1 and Rf.sup.2 are each present in a plurality of
number, a plurality of Rf.sup.1s are each identical or different
and a plurality of Rf.sup.2s are each identical or different;
R.sup.r represents a monovalent organic group having 3 to 20 carbon
atoms and having an alicyclic structure; and X.sup.+ represents a
monovalent cation.
10. The resist pattern-forming method according to claim 9, wherein
R.sup.r in the above formula (B-1) is represented by a formula (i):
##STR00033## wherein, in the formula (i), A represents a linking
group having a valency of (m+1); m is an integer of 1 to 3; and
R.sup.r1 represents a monovalent organic group having 3 to 20
carbon atoms and having an alicyclic structure.
11. A radiation-sensitive resin composition comprising: a polymer
component including a polymer having an acid-labile group; and a
radiation-sensitive acid generator, the polymer component
including, in an identical polymer or different polymers, a first
structural unit having a first hydrocarbon group, and a second
structural unit having a second hydrocarbon group, the first
hydrocarbon group being an unsubstituted or substituted branched
chain group having no greater than 8 carbon atoms or an
unsubstituted or substituted monocyclic alicyclic group having 3 to
8 ring carbon atoms, the second hydrocarbon group having an
adamantane skeleton, a molar ratio of the second hydrocarbon group
to the first hydrocarbon group being less than 1, a proportion of a
structural unit having a hydroxyl group in the polymer component to
a total of structural units in the polymer component being less
than 5 mol %, and the radiation-sensitive resin composition being
for use in a resist pattern-forming method carried out using a
developer solution containing no less than 80% by mass of an
organic solvent.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation application of
International Application No. PCT/JP2011/079736, filed Dec. 21,
2011, which claims priority to Japanese Patent Application No.
2011-016814, filed Jan. 28, 2011. The contents of these
applications are incorporated herein by reference in their
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a resist pattern-forming
method, and a radiation-sensitive resin composition.
[0004] 2. Discussion of the Background
[0005] Miniaturization of structures of various types of electronic
devices such as semiconductor devices and liquid crystal devices
has been accompanied by demands for miniaturization of resist
patterns in lithography processes, and formation of fine resist
patterns having a line width of about 90 nm using an ArF excimer
laser that is a radioactive ray with a short wavelength has been
investigated. Various compositions for resist capable of responding
to radioactive rays having such short wavelengths have been
studied. As such a composition for resist, a radiation-sensitive
resin composition has been known which generates an acid at
light-exposed sites by irradiation with a radioactive ray (i.e.,
exposure), and a catalytic action of the acid allows the difference
in dissolution rates in developing solutions to be produced between
the light-exposed site and the light-unexposed site, thereby
enabling a resist patterns to be formed on a substrate.
[0006] On the other hand, as a technique for increasing a resolving
power using a preexisting apparatus without increasing steps by
utilizing characteristic features of such radiation-sensitive resin
compositions, a technique in which an organic solvent having
polarity lower than that of aqueous alkali solutions is used as a
developer solution has been known (see Japanese Unexamined Patent
Application, Publication No. 2000-199953). Attaining a high optical
contrast is enabled when an organic solvent is used in this manner,
and as a result, a fine pattern can be formed.
[0007] When a conventional radiation-sensitive resin composition is
used in such a resist pattern-forming method in which an organic
solvent is used as a developer solution, a film loss may be caused
after resist pattern formation on the surface at light-exposed
sites, resulting from use of an organic solvent as a developer
solution. On the other hand, at light-exposed sites, a disadvantage
of impaired etching resistance may also occur due to a decrease in
the carbon content. Thus, achieving both superior etching
resistance and inhibition of the film loss has been reportedly
difficult. In addition, when the film loss is caused, improvement
of lithography characteristics involving CDU (Critical Dimension
Uniformity), MEEF (Mask Error Enhancement Factor) and resolution in
fine regions, etc., has been difficult, which may result from the
film loss. Accordingly, a radiation-sensitive resin composition and
a resist pattern-forming method capable of improving these
characteristics has been demanded.
SUMMARY OF THE INVENTION
[0008] According to one aspect of the present invention, a resist
pattern-forming method includes forming a resist coating film using
a radiation-sensitive resin composition. The resist coating film is
exposed. The exposed resist coating film is developed using a
developer solution containing no less than 80% by mass of an
organic solvent. The radiation-sensitive resin composition includes
a polymer component including a polymer having an acid-labile
group, and a radiation-sensitive acid generator. The polymer
component includes, in an identical polymer or different polymers,
a first structural unit having a first hydrocarbon group, and a
second structural unit having a second hydrocarbon group. The first
hydrocarbon group is an unsubstituted or substituted branched chain
group having no greater than 8 carbon atoms or an unsubstituted or
substituted monocyclic alicyclic group having 3 to 8 ring carbon
atoms. The second hydrocarbon group has an adamantane skeleton. A
molar ratio of the second hydrocarbon group to the first
hydrocarbon group is less than 1. A proportion of a structural unit
having a hydroxyl group in the polymer component to a total amount
of structural units in the polymer component is less than 5 mol
%.
[0009] According to another aspect of the present invention, a
radiation-sensitive resin composition includes a polymer component
including a polymer having an acid-labile group, and a
radiation-sensitive acid generator. The polymer component includes,
in an identical polymer or different polymers, a first structural
unit having a first hydrocarbon group, and a second structural unit
having a second hydrocarbon group. The first hydrocarbon group is
an unsubstituted or substituted branched chain group having no
greater than 8 carbon atoms or an unsubstituted or substituted
monocyclic alicyclic group having 3 to 8 ring carbon atoms. The
second hydrocarbon group has an adamantane skeleton. A molar ratio
of the second hydrocarbon group to the first hydrocarbon group is
less than 1. A proportion of a structural unit having a hydroxyl
group in the polymer component to a total of structural units in
the polymer component is less than 5 mol %. The radiation-sensitive
resin composition is for use in a resist pattern-forming method
carried out using a developer solution containing no less than 80%
by mass of an organic solvent.
DESCRIPTION OF THE EMBODIMENTS
[0010] According to an embodiment of the present invention made for
solving the foregoing problems, a resist pattern-forming method
includes:
[0011] (1) a resist coating film-forming step in which a
radiation-sensitive resin composition is used;
[0012] (2) an exposure step; and
[0013] (3) a development step in which a developer solution
containing no less than 80% by mass of an organic solvent is
used,
[0014] the radiation-sensitive resin composition containing:
[0015] (A) a polymer component including a polymer having an
acid-labile group (hereinafter, may be also referred to as "polymer
component (A)"); and
[0016] (B) a radiation-sensitive acid generator (hereinafter, may
be also referred to as "acid generator (B)"), the polymer component
(A) including, in an identical polymer or different polymers, (I) a
structural unit having (a1) a hydrocarbon group, and (II) a
structural unit having (a2) a hydrocarbon group,
[0017] the hydrocarbon group (a1) being an unsubstituted or
substituted branched chain group having no greater than 8 carbon
atoms or an unsubstituted or substituted monocyclic alicyclic group
having 3 to 8 carbon atoms,
[0018] the hydrocarbon group (a2) having an adamantane
skeleton,
[0019] a molar ratio of the hydrocarbon group (a2) to the
hydrocarbon group (a1) being less than 1, and
[0020] a proportion of a structural unit having a hydroxyl group in
the polymer component (A) to a total amount of structural units in
the polymer component being less than 5 mol %.
[0021] In the resist pattern-forming method according to the
embodiment of the present invention, polarity of the polymer
component (A) increases due to an action of the acid generated from
the acid generator (B) in the radiation-sensitive resin composition
at light-exposed sites, thereby making the polymer component (A)
hardly soluble in the developer solution containing an organic
solvent at a certain proportion or more, and thus a negative resist
pattern is obtained. According to the resist pattern-forming
method, as the polymer component (A), the hydrocarbon group (a1)
being an unsubstituted or substituted branched chain group having
no greater than 8 carbon atoms or an unsubstituted or substituted
monocyclic alicyclic group having 3 to 8 carbon atoms, and the
hydrocarbon group (a2) having an adamantane skeleton are included,
with a molar ratio of the hydrocarbon group (a2) to the hydrocarbon
group (a1) being less than 1. In other words, the polymer component
(A) in which: the number of the hydrocarbon group (a2) is smaller
than that of the hydrocarbon group (a1); and the proportion of the
included structural unit having a hydroxyl group is less than the
above value is used. Accordingly, both superior etching resistance
and inhibition of the film loss after pattern formation of the
resulting resist coating film can be achieved, and a resist pattern
superior in lithography characteristics such as CDU, MEEF and
resolution can be obtained.
[0022] Although the reasons for enabling both superior etching
resistance and inhibition of the film loss of a resist coating film
to be achieved by constituting as described above in the resist
pattern-forming method have not been necessarily clear, the
following reason may be envisaged. It may be considered, for
example, that when the ratio of a comparatively bulky hydrocarbon
group (a2) to a comparatively less bulky hydrocarbon group (a1)
having an adamantane skeleton contained in the polymer component
(A) falls within the above-specified range, a reduction in volume
of the resist coating film owing to elimination of the acid-labile
group can be suppressed, while maintaining the level of the carbon
content that highly correlates to etching resistance. Additionally,
it may be also considered in connection with the reason that when
the structural unit having a hydroxyl group is included in an
amount below the above range, an interaction between the hydroxyl
group and a carboxyl group generated at light-exposed sites, and
the like, which may be supposed to account for the film loss can be
reduced. Moreover, also in regard to the reason for the improvement
of lithography characteristics such as CDU, it may be considered,
for example, that a contrast between dissolution at the
light-exposed site and at the light-unexposed site further
increases as a result of adjusting the proportion of the included
hydroxyl group to be less than a given value, in addition to the
film loss inhibited as described above.
[0023] It is preferred that the structural unit (I) is represented
by the following formula (1), and the structural unit (II) is
represented by the following formula (2):
##STR00001##
[0024] wherein, in the formulae (1) and (2), R and R' each so
independently represent a hydrogen atom, a fluorine atom, a methyl
group or a trifluoromethyl group; R.sup.2 represents a monovalent
hydrocarbon group (a1); and R.sup.2 represents a monovalent
hydrocarbon group (a2), and R.sup.1 and R.sup.2 each independently
do not have or have a hydroxyl group, a carbonyl group, a cyano
group, a nitro group, a sulfonamide group or a combination
thereof.
[0025] When the structural unit (I) and the structural unit (II) in
the polymer component (A) each have the above-specified structure,
the polymer component (A) can be conveniently synthesized from the
monomers that give the structural unit (I) and the structural unit
(II), and molar ratio of the hydrocarbon group (a2) to the
hydrocarbon (a1) can be properly adjusted. As a result, improvement
of lithography characteristics such as CDU can be readily
realized.
[0026] R.sup.1 in the above formula (1) in the polymer component
(A) preferably represents an acid-labile group. When R.sup.1
included at a relatively high proportion in the polymer component
(A) represents an acid-labile group, pattern formation properties
can be improved. In addition, since R.sup.1 eliminated is
comparatively small, it is transpired by post exposure baking (PEB)
and the like following the exposure step, and is less likely to
remain in the resist coating film; therefore, lithography
characteristics such as CDU of the resultant resist pattern can be
further improved.
[0027] R.sup.2 in the above formula (2) in the polymer component
(A) preferably represents a group each represented by the following
formulae (2-1) to (2-4), an acid-labile group or a combination
thereof.
##STR00002##
[0028] wherein, in the formulae (2-1) to (2-4),
[0029] R.sup.p1, R.sup.p2 and R.sup.p3 each independently represent
a hydroxyl group, a cyano group, a nitro group or a sulfonamide
group; R.sup.a1 and R.sup.a2 each independently represent a
methylene group or an alkylene group having 2 to 10 carbon atoms;
R.sup.a3 represents a single bond, a methylene group or an alkylene
group having 2 to 10 carbon atoms; q1 is an integer of 1 to 6; and
q2 and q3 are each independently an integer of 1 to 15, wherein in
a case where R.sup.p1, R.sup.p2 and R.sup.a1 are each present in a
plurality of number, a plurality of R.sup.p1s are each identical or
different, a plurality of R.sup.p2s are each identical or different
and a plurality of R.sup.a1s are each identical or different, and
wherein * denotes a binding site to an ester group in the above
formula (2).
[0030] The above formulae (2-1) to (2-4) represent an adamantane
skeleton-containing acid-nonlabile group having a carbonyl group, a
hydroxyl group, a cyano group or a sulfonamide group. When R.sup.2
represents the group having the above-specified structure, a film
loss that may be caused by dissolution of the surface in a
developer solution containing an organic solvent at light-exposed
sites that are highly hydrophobic can be further inhibited. Also in
the case in which R.sup.2 represents an acid-labile group,
eliminated R.sup.2 is less likely to be transpired during PEB and
the like, and thus remains in the resist coating film, whereby the
effects similar to those described above can be exhibited.
[0031] The molar ratio of the hydrocarbon group (a2) to the
hydrocarbon group (a1) is preferably no less than 0.1 and no
greater than 0.9. When the molar ratio of the hydrocarbon group
(a2) to the hydrocarbon group (a1) is adjusted to fall within the
above-specified range, both etching resistance and inhibition of
the film loss of the resist coating film can be achieved at a
higher level.
[0032] The hydrocarbon group (a2) preferably has a hydroxyl group,
a carbonyl group or a combination thereof. When the hydrocarbon
group (a2) has the above-specified group, MEEF characteristics of
the resultant resist pattern can be improved.
[0033] It is preferred that the polymer component (A) further
includes a structural unit having a lactone group, a cyclic
carbonate group or a combination thereof. When the polymer
component (A) further includes the structural unit having the
above-specified group, basic characteristics as a resist such as
adhesiveness of the resultant resist coating film to a substrate
can be further improved.
[0034] The proportion of the acid-labile group in the hydrocarbon
group (a1) and the hydrocarbon group (a2) is preferably no less
than 50 mol %. When the proportion of the acid-labile group in the
hydrocarbon group (a1) and the hydrocarbon group (a2) is no less
than 50 mol %, pattern formation properties are improved, and as a
result, lithography characteristics such as CDU can be further
improved.
[0035] The radiation-sensitive acid generator (B) is preferably
represented by the following formula (B-1), and it is more
preferred that Rr in the following formula (B-1) is represented by
the following formula (i):
##STR00003##
[0036] wherein, in the formula (B-1), Rf.sup.1 and Rf.sup.2 each
independently represent a hydrogen atom, a fluorine atom, or a
fluorinated alkyl group having 1 to 4 carbon atoms; n is an integer
of 1 to 3, wherein any case in which Rf.sup.1 and Rf.sup.2 bonded
to carbon at an .alpha.-position of the sulfonate group both
represent a hydrogen atom is excluded, and in a case where Rf.sup.1
and Rf.sup.2 are each present in a plurality of number, a plurality
of Rf.sup.1s are each identical or different and a plurality of
Rf.sup.2s are each identical or different; R.sup.r represents a
monovalent organic group having 3 to 20 carbon atoms and having an
alicyclic structure; and X.sup.+ represents a monovalent
cation:
##STR00004##
[0037] wherein, in the formula (i), A represents a linking group
having a valency of (m+1); m is an integer of 1 to 3; and R.sup.r1
represents a monovalent organic group having 3 to 20 carbon atoms
and having an alicyclic structure.
[0038] Due to having an alicyclic structure similarly to the
polymer component (A), the radiation-sensitive acid generator (B)
has increased miscibility and improved dispersibility, and further
diffusion in the resist coating film is appropriately controlled.
As a result, lithography characteristics such as CDU of the
resultant resist pattern can be further improved.
[0039] The radiation-sensitive resin composition of the embodiment
of the present invention is for use in a resist pattern-forming
method carried out using a developer solution containing no less
than 80% by mass of an organic solvent, and the radiation-sensitive
resin composition contains:
[0040] (A) a polymer component including a polymer having an
acid-labile group; and
[0041] (B) a radiation-sensitive acid generator,
[0042] the polymer component (A) including, in an identical polymer
or different polymers, (I) a structural unit having (a1) a
hydrocarbon group, and (II) a structural unit having (a2) a
hydrocarbon group,
[0043] the hydrocarbon group (a1) being a unsubstituted or
substituted branched chain group having no greater than 8 carbon
atoms or an unsubstituted or substituted monocyclic alicyclic group
having 3 to 8 ring carbon atoms,
[0044] the hydrocarbon group (a2) having an adamantane
skeleton,
[0045] a molar ratio of the hydrocarbon group (a2) to the
hydrocarbon group (a1) being less than 1, and
[0046] a proportion of a structural unit having a hydroxyl group in
the polymer component (A) to a total amount of is structural units
in the polymer component being less than 5 mol %.
[0047] When the radiation-sensitive resin composition is used in a
resist pattern-forming method carried out using a developer
solution containing no less than 80% by mass of an organic solvent,
a resist pattern capable of achieving both superior etching
resistance and inhibition of the film loss of a resist coating
film, and being superior in lithography characteristics such as CDU
can be obtained.
[0048] As referred to herein, a term "branched chain group" means a
chain group having a branched structure, and does not have a cyclic
structure such as an aliphatic ring or an aromatic ring. Also, a
term "monocyclic alicyclic group" as referred to herein means a
group derived from a monocyclic aliphatic cyclic hydrocarbon by
removing one or more hydrogen atom(s) bonded to a carbon atom
constituting the carbon ring.
[0049] According to the resist pattern-forming method of the
embodiment of the present invention, and a radiation-sensitive
resin composition suited for the method, both superior etching
resistance and inhibition of the film loss of a resist coating film
can be achieved while formation of a fine pattern is enabled by
development using an organic solvent, and a resist pattern superior
in lithography characteristics such as CDU, MEEF and resolution can
be formed. The embodiments will now be described in detail.
Resist Pattern-Forming Method
[0050] An embodiment of the present invention provides a resist
pattern-forming method including: (1) resist coating film-forming
step of coating a radiation-sensitive resin composition on a
substrate (hereinafter, may be also referred to as "step (1)"); (2)
an exposure step (hereinafter, may be also referred to as "step
(2)"); and (3) a development step in which a developer solution
containing no less than 80% by mass of an organic solvent is used
(hereinafter, may be also referred to as "step (3)"), the
radiation-sensitive resin composition containing (A) a polymer
component and (B) a radiation-sensitive acid generator.
Hereinafter, each step will be described in detail.
Step (1)
[0051] In this step, the composition used in the embodiment of the
present invention is coated on a substrate to provide a resist
coating film. As the substrate, for example, conventionally
well-known substrates such as a silicon wafer and a wafer coated
with aluminum can be used. In addition, organic or inorganic
antireflective films disclosed in, for example, Japanese Examined
Patent Application, Publication No. H06-12452, Japanese Unexamined
Patent Application, Publication No. S59-93448, and the like may be
provided on the substrate.
[0052] A coating method is exemplified by spin-coating, cast
coating, roll coating, and the like. It is to be noted that the
film thickness of the resist coating film provided is typically
0.01 .mu.m to 1 .mu.m, and preferably 0.01 .mu.m to 0.5 .mu.m.
[0053] After coating the radiation-sensitive resin composition, a
solvent in the coating film may be volatilized as needed by
prebaking (PB). According to heating conditions of PB, the
temperature may be appropriately selected depending on the
formulation of the radiation-sensitive resin composition, and is
typically about 30.degree. C. to 200.degree. C. and preferably
50.degree. C. to 150.degree. C.
[0054] A protective film as disclosed in Japanese Patent
Application Publication No. H05-188598 or the like may be provided
on the resist layer so that the resist film is not affected by
basic impurities and the like contained in the environmental
atmosphere. Furthermore, in order to prevent outflow of the acid
generating agent and the like from the resist layer, a liquid
immersion lithography protective film as disclosed in Japanese
Patent Application Publication No. 2005-352384 or the like may be
provided on the resist layer. These techniques may be used in
combination.
Step (2)
[0055] In this step, the resist coating film provided in the step
(1) is exposed at a desired region by carrying out reduction
projection through a mask having a specific pattern, and as needed
an immersion liquid. For example, an isolated trench (iso-trench)
pattern can be formed by carrying out reduced projection 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
depending on the desired pattern and the mask pattern. When the
exposure is carried out at least twice, the exposure is preferably
carried out continuously. When the exposure is carried out a
plurality of times, for example, first reduced projection exposure
is carried out through a line-and-space pattern mask at a desired
region, and subsequently second reduced projection exposure is
carried out such that lines cross over light-exposed sites
subjected to the first exposure. The first light-exposed sites are
preferably orthogonal to the second light-exposed sites. Due to
being orthogonal with each other, a perfect circular contact hole
pattern can be easily formed at light-unexposed sites surrounded by
light-exposed sites. It is to be noted that examples of the
immersion liquid for use in the exposure include water, a
fluorine-containing inert liquid, and the like. It is preferred
that the immersion liquid be transparent to the 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. When an ArF excimer laser
(wavelength: 193 nm) is used as the exposure light source, it is
preferred to use water from the viewpoint of availability and ease
of handling, in addition to the viewpoints described above. In the
case in which water is used, an additive that decreases the surface
tension of water and increases surface active force may be added in
a slight amount. It is preferred that the additive does not
dissolve the resist layer on a wafer, and has a is negligible
influence on an optical coating of an inferior face of a lens.
Water employed is preferably distilled water.
[0056] A radioactive ray used for the exposure is appropriately
selected in accordance with the type of the acid generator (B), and
is exemplified by an ultraviolet ray, a far ultraviolet ray, an
X-ray, a charged particle ray, and the like. Among these, a far
ultraviolet ray typified by an ArF excimer laser or a KrF excimer
laser (wavelength: 248 nm) is preferred, and an ArF excimer laser
is more preferred. The exposure conditions such as an exposure dose
are appropriately selected in accordance with the formulation, and
type of additives etc. of the radiation-sensitive resin
composition. The resist pattern-forming method of the embodiment of
the present invention may include a plurality of the exposure
steps, and light sources employed in the exposure carried out a
plurality of times may be identical or different, but an ArF
excimer laser beam is preferably used in the first exposure
step.
[0057] In addition, it is preferred that post-exposure baking (PEB)
is carried out after the exposure. When the PEB is carried out, a
dissociate reaction of an acid-labile group in the
radiation-sensitive resin composition can smoothly proceed.
According to heating conditions of PEB, the temperature may be
typically 30.degree. C. to 200.degree. C., and preferably
50.degree. C. to 170.degree. C.
Step (3)
[0058] In this step, after the exposure in the step (2),
development is carried out using a negative developer solution
containing no less than 80% by mass of an organic solvent to form a
pattern. The negative developer solution as referred to means a
developer solution that selectively dissolve and remove poorly
light-exposed sites and light-unexposed sites. The organic solvent
contained in the negative developer solution is preferably at least
one selected from the group consisting of an alcohol solvent, an
ether solvent, a ketone organic solvent, an amide solvent, an ester
organic solvent and a hydrocarbon solvent.
[0059] Examples of the alcohol solvent include:
[0060] 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, benzyl alcohol and
diacetone alcohol;
[0061] 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;
[0062] partially etherified polyhydric alcohol 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.
[0063] Examples of the ether solvent include diethyl ether,
dipropyl ether, dibutyl ether, diphenyl ether, methoxybenzene, and
the like.
[0064] Examples of the ketone solvent include acetone, methyl ethyl
ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl
ketone, methyl iso-butyl ketone, methyl n-pentyl ketone, ethyl
n-butyl ketone, methyl n-hexyl ketone, di-iso-butyl ketone,
trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone,
cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonyl
acetone, acetophenone, and the like.
[0065] Examples of the amide solvent include
N,N'-dimethylimidazolidinone, N-methylformamide,
N,N-dimethylformamide, N,N-diethylformamide, acetamide,
N-methylacetamide, N,N-dimethylacetamide, N-methylpropionamide,
N-methylpyrrolidone, and the like.
[0066] Examples of the ester solvent include diethyl carbonate,
propylene carbonate, methyl acetate, ethyl acetate,
.gamma.-butyrolactone, .gamma.-valerolactone, 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,
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, dipropylene glycol
monoethyl ether acetate, glycol diacetate, methoxytriglycol
acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate,
diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate,
n-butyl lactate, n-amyl lactate, diethyl malonate, dimethyl
phthalate, diethyl phthalate, and the like.
[0067] Examples of the hydrocarbon solvent include:
[0068] aliphatic hydrocarbon solvents such as n-pentane,
iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane,
2,2,4-trimethyl pentane, n-octane, iso-octane, cyclohexane and
methylcyclohexane;
[0069] aromatic hydrocarbon solvents such as benzene, toluene,
xylene, mesitylene, ethylbenzene, trimethylbenzene,
methylethylbenzene, n-propylbenzene, i-propylbenzene,
diethylbenzene, i-butylbenzene, triethylbenzene, di-i-propylbenzene
and n-amylnaphthalene, and the like.
[0070] Of these, n-butyl acetate, isopropyl acetate, n-amyl
acetate, methyl ethyl ketone, methyl-n-butyl ketone, and
methyl-n-amyl ketone are preferred. These organic solvents may be
used either alone, or in combination of two or more thereof.
[0071] The content of the organic solvent in the developer solution
is no less than 80% by mass. When the content of the organic
solvent in the developer solution is no less than 80% by mass, a
contrast of the pattern resulting from the exposure, i.e.,
depending on being exposed or unexposed, can be improved, and
consequently, a resist pattern that is superior in development
characteristics and lithography characteristics can be formed. It
is to be noted that examples of components other than the organic
solvent include water, a silicon oil, and the like.
[0072] A surfactant may be added to the developer solution in an
appropriate amount as needed. As the surfactant, for example, an
ionic or nonionic fluorochemical surfactant and/or a silicon
surfactant, and the like may be used.
[0073] Examples of the development method include a dipping method
that immerses the substrate in a container filled with the
developer for a given time, a puddle method that allows the
developer to be present on the surface of the substrate due to
surface tension for a given time, a spraying method that sprays the
developer onto the surface of the substrate, a dynamic dispensing
method that applies the developer to the substrate that is rotated
at a constant speed while scanning with a developer application
nozzle at a constant speed, and the like.
[0074] In the resist pattern-formation, it is preferred that a step
of rinsing the resist coating film with a rinse agent be carried
out after the development in the step (3). Moreover, also as the
rinse agent in the rinsing step, an organic solvent may be used,
whereby scum 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, an alcohol solvent and an 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.
[0075] 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, even
more preferably no greater than 5% by mass, and particularly
preferably no greater than 3% by mass. When the moisture content is
no greater than 10% by mass, favorable development characteristics
can be attained. It is to be noted that a surfactant may be added
to a rinse agent described later.
[0076] Examples of the rinsing method include a spinning method
that applies the rinse agent to the substrate that is rotated at a
constant speed, a dipping method that immerses the substrate in a
container filled with the rinse agent for a given time, a spraying
method that sprays the rinse agent onto the surface of the
substrate, and the like.
Radiation-Sensitive Resin Composition
[0077] The radiation-sensitive resin composition for use in the
resist pattern-forming method according to the embodiment of the
present invention contains (A) a polymer component and (B) an acid
generator. Furthermore, optional components may be contained within
a range not leading to impairment of the effects of the embodiment
of the present invention. Hereinafter, each component will be
described in detail.
Polymer Component (A)
[0078] The polymer component (A) includes a polymer having an
acid-labile group. The polymer component (A) may include
constituting one type of polymer, or a plurality of types of
polymers. The mode of including the acid-labile group in the
polymer component (A) is not particularly limited, and the polymer
component (A) may include only the polymer having an acid-labile
group, or may include the polymer having an acid-labile group and a
polymer not having an acid-labile group. The acid-labile group
means a group that substitutes for a hydrogen atom in a carboxyl
group, a hydroxyl group and the like, and is dissociated by an
action of an acid generated from the acid generator (B) upon
exposure.
[0079] The polymer component (A) includes,
[0080] in an identical polymer or different polymers, (I) a
structural unit having (a1) a hydrocarbon group, and (II) a
structural unit having (a2) a hydrocarbon group,
[0081] the hydrocarbon group (a1) being a unsubstituted or
substituted branched chain group having no greater than 8 carbon
atoms or an unsubstituted or substituted monocyclic alicyclic group
having 3 to 8 ring carbon atoms,
[0082] the hydrocarbon group (a2) having an adamantane
skeleton,
[0083] a molar ratio of the hydrocarbon group (a2) to the
hydrocarbon group (a1) being less than 1, and
[0084] a proportion of the structural unit having a hydroxyl group
being less than 5 mol %.
[0085] The radiation-sensitive resin composition, due to the
polymer component (A) having the above specified structure, enables
both superior etching resistance and a film loss of the resist
coating film to be achieved. In addition, a combination of the
radiation-sensitive resin composition containing the polymer
component (A) with the characteristic resist pattern-forming method
can form a resist pattern that is superior in lithography
characteristics such as CDU.
[0086] The mode of including the structural unit (I) and the
structural unit (II) in the polymer component (A) is not
particularly limited, and the polymer component (A) may include a
polymer having both the structural unit (I) and the structural unit
(II), or may include a polymer having the structural unit (I) and a
polymer having the structural unit (II).
Structural Unit (I)
[0087] The structural unit (I) has the hydrocarbon group (a1) that
is an unsubstituted or substituted branched chain group having no
greater than 8 carbon atoms or an unsubstituted or substituted
monocyclic alicyclic group having 3 to 8 ring carbon atoms. The
valency of the hydrocarbon group (a1) is not particularly limited.
The hydrocarbon group (a1) may be either a monovalent group such as
an alkyl group, an alkenyl group, an alkynyl group, a monocyclic
cycloalkyl group or a group derived therefrom by substituting a
part or all of hydrogen atoms, or a divalent or polyvalent group
such as an alkanediyl group, an alkanetriyl group, a
cycloalkanediyl group, a cycloalkanetriyl group or a group derived
therefrom by substituting a part or all of hydrogen atoms, as long
as the hydrocarbon group (a1) is an unsubstituted or substituted
branched chain group having no greater than 8 carbon atoms or an
unsubstituted or substituted monocyclic alicyclic group having 3 to
8 ring carbon atoms. In light of improvement of lithography
characteristics such as CDU, as a result of appropriately reduced
rigidity of the polymer of the polymer component (A), a monovalent
group is preferred. The number of the hydrocarbon group (a1) in the
structural unit (I) is not particularly limited, which may be
either one, or greater, and preferably one. The structural unit (I)
may have one, or two or more types of the hydrocarbon group (a1).
The substituent is not particularly limited, and examples thereof
include polar groups such as a hydroxyl group, a carbonyl group, a
cyano group, a nitro group and a sulfonamide group, alkyl groups,
alkyl groups having the polar group, and the like.
[0088] The structural unit (I) is preferably the structural unit
represented by the above formula (1).
[0089] In the above formula (1), R represents a hydrogen atom, a
fluorine atom, a methyl group or a trifluoromethyl group; R.sup.1
represents a monovalent hydrocarbon group (a1), wherein R.sup.1 may
have a hydroxyl group, a carbonyl group, a cyano group, a nitro
group, a sulfonamide group or a combination thereof (i.e., a polar
group).
[0090] The structural unit (I) represented by the above formula (1)
has a monovalent hydrocarbon group (a1), whereby rigidity of the
polymer of the polymer component (A) is appropriately reduced, and
as a result, lithography characteristics such as CDU of the
resultant resist pattern can be improved. In addition, a monomer
that gives such a structural unit (I) can be conveniently
synthesized, and synthesis of the polymer component (A) is enabled
using the monomer by highly adjusting the proportion of the
structural unit (I) included.
[0091] The hydrocarbon group (a1) may or may not have a polar
group.
[0092] Examples of the monovalent hydrocarbon group (a1) that is
represented by R.sup.1 and does not have a polar group include:
[0093] branched chain groups having no greater than 8 carbon such
as a methyl group, an ethyl group, a n-propyl group, an i-propyl
group, a n-butyl group, an i-butyl group, a sec-butyl group, a
t-butyl group, a n-pentyl group, an i-pentyl group, a sec-pentyl
group, a t-pentyl group, a neo-pentyl group, a n-hexyl group, an
i-hexyl group, a sec-hexyl group, a t-hexyl group, a neo-hexyl
group, a n-heptyl group, an i-heptyl group, a sec-heptyl group, a
t-heptyl group, a neo-heptyl group, a n-octyl group, an i-octyl
group, a sec-octyl group, a t-octyl group and a neo-octyl
group;
[0094] monocyclic alicyclic groups having 3 to 8 ring carbon atoms
such as a cyclopropyl group, a 1-methylcyclopropyl group, a
cyclobutyl group, a 1-methylcyclobutyl group, a 1-ethylcyclobutyl
group, a cyclopentyl group, a 1-methylcyclopentyl group, a
1-ethylcyclopentyl group, a 1-n-propylcyclopentyl group, a
1-1-propylcyclopentyl group, a cyclohexyl group, a
1-methylcyclohexyl group, a 1-ethylcyclohexyl group, a
1-n-propylcyclohexyl group, a 1-1-propylcyclohexyl group, a
cycloheptyl group, a 1-methylcycloheptyl group, a
1-ethylcycloheptyl group, a 1-n-propylcycloheptyl group, a
1-1-propylcycloheptyl group, a cyclooctyl group, a
1-methylcyclooctyl group, a 1-ethylcyclooctyl group, a
1-n-propylcyclooctyl group and a 1-1-propylcyclooctyl group, and
the like.
[0095] Examples of the hydrocarbon group (a1) that is represented
by R.sup.1 and has a polar group include groups derived by
substituting a part or all of hydrogen atoms of the aforementioned
hydrocarbon group (a1) that does not have the polar group for the
polar group described above.
[0096] The monovalent hydrocarbon group (a1) represented by R.sup.1
may or may not be an acid-labile group, and is preferably an
acid-labile group. When R.sup.1 included at a relatively high
proportion in the polymer component (A) represents an acid-labile
group, pattern formation properties can be improved. In addition,
since R.sup.1 eliminated is comparatively small, it is transpired
by PEB and the like. As a result, lithography characteristics such
as CDU of the resultant resist pattern can be improved.
[0097] Examples of the monovalent hydrocarbon group (a1)
represented by R.sup.1 that is an acid-labile group include a
t-butyl group, a t-pentyl group, a t-hexyl group, a t-heptyl group,
a t-octyl group, a 1-methylcyclopropyl group, a 1-methylcyclobutyl
group, a 1-ethylcyclobutyl group, a 1-methylcyclopentyl group, a
1-ethylcyclopentyl group, a 1-n-propylcyclopentyl group, a
1-1-propylcyclopentyl group, a 1-methylcyclohexyl group, a
1-ethylcyclohexyl group, a 1-n-propylcyclohexyl group, a
1-1-propylcyclohexyl group, a 1-methylcycloheptyl group, a
1-ethylcycloheptyl group, a 1-n-propylcycloheptyl group, a
1-1-propylcycloheptyl group, a 1-methylcyclooctyl group, a
1-ethylcyclooctyl group, a 1-n-propylcyclooctyl group, a
1-1-propylcyclooctyl group, and the like.
[0098] Examples of the structural unit (I) having a hydrocarbon
group (a1) that does not have a polar group include structural
units represented by the following formulae.
##STR00005##
[0099] In the above formulae, R is as defined in the above formula
(1).
[0100] Examples of the structural unit (I) having a hydrocarbon
group (a1) that has a polar group include structural units
represented by the following formulae.
##STR00006##
[0101] In the above formulae, R is as defined in the above formula
(1).
Structural Unit (II)
[0102] The structural unit (II) has the hydrocarbon group (a2)
having an adamantane skeleton. Due to having a bulky adamantane
skeleton, the hydrocarbon group (a2) can enhance etching resistance
of the resulting resist coating film. The valency of the
hydrocarbon group (a2) is not particularly limited. The hydrocarbon
group (a2) may be either a monovalent group such as an adamantyl
group, or a divalent or polyvalent group such as an adamantanediyl
group or an adamantanetriyl group as long as it has an adamantane
skeleton. In light of improvement of lithography characteristics
such as CDU, as a result of appropriately reduced rigidity of the
polymer of the polymer component (A), a monovalent group is
preferred. The number of the hydrocarbon group (a2) in the
structural unit (II) is not particularly limited, which may be
either one, o4r greater, and preferably one. The structural unit
(II) may have one, or two or more types of the hydrocarbon group
(a2). Furthermore, a part or all of hydrogen atoms of the
hydrocarbon group (a2) may be substituted by the aforementioned
polar group, alkyl group, alicyclic hydrocarbon group, a combined
group thereof or the like.
[0103] The structural unit (II) is preferably the structural unit
represented by the above formula (2).
[0104] In the above formula (2), R represents a hydrogen atom, a
fluorine atom, a methyl group or a trifluoromethyl group; R.sup.2
represents a monovalent hydrocarbon group (a2), wherein R.sup.2 may
have a hydroxyl group, a carbonyl group, a cyano group, a nitro
group, a sulfonamide group or a combination thereof (i.e., a polar
group).
[0105] The structural unit (II) represented by the above formula
(2) has a monovalent hydrocarbon group (a2), whereby rigidity of
the polymer of the polymer component (A) is appropriately reduced,
and as a result, lithography characteristics such as CDU of the
resultant resist pattern can be improved. In addition, a monomer
that gives such a structural unit (II) can be conveniently
synthesized, and synthesis of the polymer component (A) is enabled
using the monomer by highly adjusting the proportion of the
structural unit (II) included.
[0106] The hydrocarbon group (a2) may or may not have the polar
group.
[0107] Examples of the monovalent hydrocarbon group (a2) that is
represented by R.sup.2 and does not have a polar group include:
[0108] a 1-adamantyl group, a 2-adamantyl group, a
2-methyl-2-adamantyl group, a 2-ethyl-2-adamantyl group, a
2-n-propyl-2-adamantyl group, a 2-1-propyl-2-adamantyl group, a
1-adamantyl-2-propyl group, a 2-adamantyl-2-propyl group, and the
like.
[0109] Examples of the hydrocarbon group (a2) having a polar group
include groups derived from the monovalent hydrocarbon group (a2)
represented by R.sup.2 by substituting a part or all of hydrogen
atoms by a polar group.
[0110] The monovalent hydrocarbon group (a2) represented by R.sup.2
may or may not be an acid-labile group.
[0111] Examples of the monovalent hydrocarbon group (a2)
represented by R.sup.2 that is an acid-labile group include a
2-methyl-2-adamantyl group, a 2-ethyl-2-adamantyl group, a
2-n-propyl-2-adamantyl group, a 2-1-propyl-2-adamantyl group, a
1-adamantyl-2-propyl group, a 2-adamantyl-2-propyl group, and the
like.
[0112] The hydrocarbon group (a2) preferably used has the polar
group described above. When the hydrocarbon group (a2) has the
polar group, a film loss which is believed to mainly result from an
adamantane skeleton can be effectively inhibited. Examples of the
polar group include a hydroxyl group, a carbonyl group, a cyano
group, a nitro group, a sulfonamide group or a combination thereof,
and of these, in light of improvement of MEEF characteristics, a
hydroxyl group, a carbonyl group or a combination thereof is more
preferred.
[0113] The hydrocarbon group (a2) having a polar group is
preferably any one of groups each represented by the above formula
(2-1) to (2-4), or a combination thereof.
[0114] In the above formulae (2-1) to (2-4),
[0115] R.sup.p1, R.sup.p2 and R.sup.p3 each independently represent
a hydroxyl group, a cyano group, a nitro group or a sulfonamide
group; R.sup.a1 and R.sup.a2 each independently represent a
methylene group or an alkylene group having 2 to 10 carbon atoms;
R.sup.a1 represents a single bond or a methylene group; q1 is an
integer of 1 to 6; and q2 and q3 are each independently an integer
of 1 to 15, wherein in a case where R.sup.p1, R.sup.p2 and R.sup.a1
are each present in a plurality of number, a plurality of R.sup.p1s
are each identical or different, a plurality of R.sup.p2s are each
identical or different and a plurality of R.sup.a1s are each
identical or different, and wherein * denotes a binding site to an
ester group in the above formula (2).
[0116] Examples of the alkylene group having 2 to 10 carbon atoms
represented by R.sup.a1 and R.sup.a2 include an ethylene group, a
1,2-propylene group, a 1,3-propylene group, a 1,2-butylene group, a
1,3-butylene group, a 1,4-butylene group, a 1,5-pentylene group, a
1,6-hexylene group, a 1,7-heptylene group, a 1,8-octylene group, a
1,9-nonylene group, a 1,10-decylene group, and the like.
[0117] Specific examples of the group represented by the above
formula (2-1) include groups represented by the following
formulae.
##STR00007##
[0118] In the above formulae, * denotes a binding site to an ester
group in the above formula (2).
[0119] Specific examples of the group represented by the above
formula (2-2) include groups represented by the following
formulae.
##STR00008##
[0120] In the above formulae, * denotes a binding site to an ester
group in the above formula (2).
[0121] Specific examples of the group represented by the above
formula (2-3) include groups represented by the following
formulae.
##STR00009##
[0122] In the above formulae, * denotes a binding site to an ester
group in the above formula (2).
[0123] Specific examples of the group represented by the above
formula (2-4) include groups represented by the following
formulae.
##STR00010##
[0124] In the above formulae, * denotes a binding site to an ester
group in the above formula (2).
[0125] Examples of the structural unit (II) having a hydrocarbon
group (a2) that does not have a polar group include structural
units represented by the following formulae.
##STR00011##
[0126] In the above formulae, R' is as defined in the above formula
(2).
[0127] In addition, examples of the structural unit (II) having a
hydrocarbon group (a2) that has a polar group include structural
units represented by the following formulae.
##STR00012##
[0128] In the above formulae, R' is as defined in the above formula
(2).
Relationship Between Hydrocarbon Group (a1) and Hydrocarbon Group
(a2)
[0129] In the polymer component (A), the molar ratio of the
hydrocarbon group (a2) to the hydrocarbon group (a1) should be
necessarily less than 1. When the molar ratio of the hydrocarbon
group (a2) to the hydrocarbon group (a1) is less than 1, it is
believed that suppression of dissolution of the polymer component
(A) at light-exposed sites can be balanced with a high content of
carbon of the polymer component (A), and consequently, both
superior etching resistance and inhibition of the film loss after
pattern formation of the resulting resist coating film can be
achieved. Additionally, a resist pattern that is superior in
lithography characteristics such as CDU can be obtained.
[0130] The molar ratio of the hydrocarbon group (a2) to the
hydrocarbon group (a1) is preferably no less than 0.1 and no
greater than 0.9, more preferably no less than 0.15 and no greater
than 0.85, still more preferably no less than 0.2 and no greater
than 0.8, and particularly preferably no less than 0.3 and no
greater than 0.7. When the molar ratio is adjusted to fall within
the above range, inhibition of the film loss of the resist coating
film and etching resistance can be both achieved at a higher
level.
[0131] The proportion of the acid-labile group in the hydrocarbon
group (a1) and the hydrocarbon group (a2) is preferably no less
than 50 mol %. When the proportion of the acid-labile group in the
hydrocarbon group (a1) and the hydrocarbon group (a2) is no less
than 50 mol %, lithography characteristics such as CDU can be
further improved. When the proportion of the acid-labile group is
less than 50 mol %, pattern formation properties tend to be
deteriorated. The proportion of the acid-labile group is more
preferably no less than 60 mol %, and still more preferably no less
than 70 mol %.
[0132] The proportion of the structural unit (I) included in the
polymer component (A) with respect to the entire structural units
constituting polymer component (A) is preferably 20 mol % to 80 mol
%, more preferably 25 mol % to 70 mol %, and still more preferably
30 mol % to 60 mol %. When the proportion of the structural unit
(I) included is less than 20 mol %, pattern formation properties
may be deteriorated. On the other hand, when the proportion of the
structural unit (I) included exceeds 80 mol %, the etching
resistance tends to be impaired. It is to be noted that the polymer
component (A) may include one, or two or more types of the
structural unit (I).
[0133] The proportion of the structural unit (II) included in
polymer component (A) with respect to the entire structural units
constituting the polymer component (A) is preferably 5 mol % to 40
mol %, more preferably 5 mol % to 35 mol %, and still more
preferably 10 mol % to 30 mol %. When the proportion of the
structural unit (II) included is less than 5 mol %, etching
resistance tends to be impaired. On the other hand, when the
proportion of the structural unit (II) included exceeds 40 mol %,
resolution tends to be impaired. It is to be noted that the polymer
component (A) may include one, or two or more types of the
structural unit (II).
Structural Unit (III)
[0134] It is preferred that the polymer component (A) further
includes a structural unit having a lactone group, a cyclic
carbonate group or a combination thereof (hereinafter, may be also
referred to as "structural unit (III)"). When the polymer component
(A) further includes a structural unit having a lactone group
and/or a cyclic carbonate group, basic characteristics as a resist
such as adhesiveness of the resist coating film to a substrate can
be more improved. In addition, solubility of the resist coating
film in a developer solution can be improved. The "lactone group"
as herein referred to indicates a cyclic group having one ring that
includes a bond represented by --O--C(O)-- (i.e., lactone ring).
Further, the "cyclic carbonate group" indicates a cyclic group
having one ring that includes a bond represented by --O--C(O)--O--
(i.e., cyclic carbonate ring). The lactone ring or the cyclic
carbonate ring is counted as a first ring, and when only the
lactone ring or the cyclic carbonate ring is included, the group is
referred to as a "monocyclic group", whereas when other ring
structure is further included, the group is referred to as a
"polycyclic group", irrespective of its structure.
[0135] Examples of the structural unit having a lactone group
include structural units represented by the following formulae.
##STR00013## ##STR00014##
##STR00015##
[0136] In the above formulae, R.sup.L1 represents a hydrogen atom,
a fluorine atom, a methyl group or a trifluoromethyl group.
[0137] Examples of the structural unit having a cyclic carbonate
group include structural units represented by the following
formulae.
##STR00016## ##STR00017##
[0138] In the above formulae, R.sup.L1 represents a hydrogen atom,
a fluorine atom, a methyl group or a trifluoromethyl group.
[0139] The proportion of the structural unit (III) included in the
polymer component (A) with respect to the entire structural units
constituting the polymer component (A) is preferably 10 mol % to 80
mol %, more preferably 20 mol % to 70 mol %, and still more
preferably 25 mol % to 60 mol %. When the proportion of the
structural unit (III) included is less than 10 mol %, improvement
of the adhesiveness of the resist coating film to a substrate and
the like may fail. On the other hand, when the proportion of the
structural unit (III) included exceeds 80 mol %, the pattern
formation properties may be deteriorated. It is to be noted that
the polymer component (A) may include one, or two or more types of
the structural unit (III).
Other Structural Unit
[0140] The polymer component (A) may further have, in addition to
the structural units (I) to (III) described above, other structural
unit such as a structural unit having a hydroxyl is group not
included in the structural unit (I) and the structural unit
(II).
Proportion of the Structural Unit Having a Hydroxyl Group
[0141] In the embodiment of the present invention, a proportion of
the structural unit having a hydroxyl group in the polymer
component (A) should be necessarily less than 5 mol % with respect
to the entire structural units constituting the polymer component
(A). When the proportion of the structural unit having a hydroxyl
group in the polymer component (A) is less than 5 mol %, owing to a
synergistic effect with the aforementioned ratio of the hydrocarbon
group (a2) to the hydrocarbon group (a1) being less than the given
value, achieving both superior etching resistance and inhibition of
the film loss after pattern formation of the resulting resist
coating film is enabled. Moreover, in addition to inhibition of the
film loss, a change in polarity of the polymer component (A) after
dissociation of the acid-labile group of the polymer component (A)
can be more increased, and as a result, lithography characteristics
such as CDU can be improved.
[0142] In the resist pattern-forming method according to the
embodiment of the present invention, reasons for exhibiting the
effects described above when a proportion of the structural unit
having a hydroxyl group in the polymer component (A) is adjusted to
be less the above value are not necessarily clear. However, it may
be considered that, for example, the content of carbon of the
polymer component (A) is increased, and an interaction of the
hydroxyl group with the carboxyl group generated at the
light-exposed site, which interaction being presumed to account for
the film loss. Moreover, also in regard to the reasons for
improvement of lithography characteristics such as CDU, it is
considered that, for example, a contrast between dissolution at the
light-exposed site and at the light-unexposed site further
increased by adjusting the proportion of the hydroxyl group to be
less than a given value. It is believed that both superior etching
resistance and inhibition of the film loss are achieved, and
superior lithography characteristics such as CDU are exhibited
owing to a synergistic effect resulting from these reasons and the
aforementioned ratio of the hydrocarbon group (a2) to the
hydrocarbon group (a1) falling within the specified range.
[0143] The structural unit having a hydroxyl group is not
particularly limited when it constitutes the polymer component (A)
as long as the structural unit has a hydroxyl group, and may be
either the structural unit (I) or the structural unit (II), or may
be a structural unit other than these. The number of the hydroxyl
group in the structural unit having a hydroxyl group may be one, or
two or greater, and in light of a great change in polarity of the
polymer component (A) after formation of the resist pattern, the
number of the hydroxyl group is preferred as small as possible,
more preferably no greater than two, and particularly preferably
one. Also, the position of the hydroxyl group in the structural
unit having a hydroxyl group is not particularly limited.
[0144] The proportion of the structural unit having a hydroxyl
group in the polymer component (A) is preferably no greater than 4
mol %, more preferably no greater than 2 mol %, and particularly
preferably 0 mol %. In other words, it is particularly preferred
that the polymer component (A) does not have a structural unit
having a hydroxyl group.
[0145] Specific examples of the structural unit having a hydroxyl
group include in addition to those exemplified as the structural
unit (I) and the structural unit (II) above, for example,
structural units represented by the following formulae.
##STR00018##
[0146] In the above formulae, R'' represents a hydrogen atom, a
fluorine atom, a methyl group or a trifluoromethyl group.
Synthesis Method of Polymer Component (A)
[0147] The polymer constituting the polymer component (A) may be
prepared, for example, by polymerizing the monomer that corresponds
to each predetermined structural unit in an appropriate solvent
using a radical polymerization initiator. The polymer (A) is
preferably synthesized according to a method such as, e.g.: a
method in which a solution containing a monomer and a radical
initiator is added dropwise to a solution containing a reaction
solvent or a monomer to permit a polymerization reaction; a method
in which a solution containing a monomer, and a solution containing
a radical initiator are each separately added dropwise to a
solution containing a reaction solvent or a monomer to permit a
polymerization reaction; and a method in which a plurality of
solutions each containing a monomer, and a solution containing a
radical initiator are each separately added dropwise to a solution
containing a reaction solvent or a monomer to permit a
polymerization reaction.
[0148] The resin obtained by the polymerization reaction may be
recovered preferably by a reprecipitation technique. More
specifically, after the polymerization reaction is completed, the
polymerization mixture is charged into a solvent for
reprecipitation, whereby a target resin is recovered in the form of
powder. As the reprecipitation solvent, an alcohol, an alkane or
the like may be used either alone or as a mixture of two or more
thereof. Alternatively to the reprecipitation technique, liquid
separating operation, column operation, ultrafiltration operation
or the like may be employed to recover the resin through
eliminating low molecular components such as monomers and
oligomers.
[0149] The polystyrene equivalent weight average molecular weight
(Mw) of the polymer component (A) as determined by gel permeation
chromatography (GPC) is not particularly limited, and preferably no
less than 1,000 and no greater than 500,000, more preferably no
less than 2,000 and no greater than 400,000, and particularly
preferably no less than 3,000 and no greater than 300,000. When the
Mw is less than 1,000, heat resistance when prepared to give a
resist tends to be impaired. On the other hand, when the Mw of the
polymer component (A) exceeds 500,000, developability when prepared
to give a resist tends to be decreased.
[0150] Furthermore, the ratio (Mw/Mn) of Mw to the polystyrene
equivalent number average molecular weight (Mn) as determined by
GPC of the polymer component (A) is typically 1 or greater and 5 or
less, preferably 1 or greater and 3 or less, and more preferably 1
or greater and 2 or less. When the ratio Mw/Mn falls within such a
range, the resist coating film may be superior in resolving
performances.
[0151] The Mw and Mn as referred to herein mean values determined
by GPC using GPC columns (manufactured by Tosoh Corporation, "G2000
HXL".times.2, "G3000 HXL".times.1 and "G4000 HXL".times.1), under
conditions involving a flow rate of 1.0 mL/min, an elution solvent
of tetrahydrofuran and a column temperature of 40.degree. C., and
with monodisperse polystyrene as a standard.
(B) Acid Generator
[0152] The acid generator (B) generates an acid upon exposure, and
the acid allows an acid-labile group present in the polymer (A) to
be dissociated to generate an acid. The mode of incorporation of
the acid generator (B) into the radiation-sensitive resin
composition may be a form of being incorporated as a compound as
described below (hereinafter, may be referred to as "acid
generating agent (B)"), a form of being incorporated as a part of a
polymer, or a combination of these two forms.
[0153] The acid generating agent (B) is exemplified by an onium
salt compound, a sulfonimide compound, a halogen-containing
compound, a diazo ketone compound, and the like. Of these acid
generating agents (B), an onium salt compound is preferred.
[0154] Examples of the onium salt compound include sulfonium salts
(including tetrahydrothiophenium salts), iodonium salts,
phosphonium salts, diazonium salts, pyridinium salts, and the
like.
[0155] 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 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,
triphenylphosphonium
1,1,2,2-tetrafluoro-6-(1-adamantanecarbonyloxy)-hexane-1-sulfonate,
and the like. Among these, triphenylsulfonium
trifluoromethanesulfonate, triphenylsulfonium
nonafluoro-n-butanesulfonate,
2-adamantyl-1,1-difluoroethane-1-sulfonate,
2-adamantyl-1,1-difluoroethane-1-sulfonate and triphenylphosphonium
1,1,2,2-tetrafluoro-6-(1-adamantanecarbonyloxy)-hexane-1-sulfonate
are preferred.
[0156] 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. Among these tetrahydrothiophenium
salts, 1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium
nonafluoro-n-butanesulfonate,
1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium
perfluoro-n-octanesulfonate and
1-(3,5-dimethyl-4-hydroxyphenyl)tetrahydrothiophenium
nonafluoro-n-butanesulfonate are preferred.
[0157] 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. Among
these iodonium salts, bis(4-t-butylphenyl)iodonium
nonafluoro-n-butanesulfonate is preferred.
[0158] Examples of the sulfonimide compound include
N-(trifluoromethanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmid-
e,
N-(nonafluoro-n-butanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarbox-
ylmide,
N-(perfluoro-n-octanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dica-
rboxylmide,
N-(2-bicyclo[2.2.1]hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy)bicyclo-
[2.2.1]hept-5-ene-2,3-dicarboxylmide,
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-dicarboxylmide,
N-(camphorsulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmide,
and the like. Among these sulfonimide compounds,
N-(trifluoromethanesulfonyloxy)bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylmid-
e is preferred.
[0159] The acid generator (B) is preferably represented by the
above formula (B-1).
[0160] Due to having an alicyclic structure, similarly to the
polymer component (A) described above, the acid generator (B)
represented by the above formula (B-1) has increased miscibility
with the polymer component (A) in the radiation-sensitive resin
composition, thereby leading to improvement of dispersibility. In
addition, diffusion in the resist coating film is appropriately
controlled. As a result, lithography characteristics such as CDU of
the resultant resist pattern can be improved.
[0161] In the above formula (B-1), Rf.sup.1 and Rf.sup.2 each
independently represent a hydrogen atom, a fluorine atom, or a
fluorinated alkyl group having 1 to 4 carbon atoms; n is an integer
of 1 to 3, wherein any case in which Rf.sup.1 and Rf.sup.2 bonded
to carbon at an .alpha.-position of the sulfonate group both
represent a hydrogen atom is excluded, and in a case where Rf.sup.1
and Rf.sup.2 are each present in a plurality of number, a plurality
of Rf.sup.1s are each identical or different and a plurality of
Rf.sup.2s are each identical or different; R.sup.r represents a
monovalent organic group having 3 to 20 carbon atoms and having an
alicyclic structure; and X.sup.+ represents a monovalent
cation.
[0162] Examples of the fluorinated alkyl group having 1 to 4 carbon
atoms represented by Rf.sup.1 and Rf.sup.2 include a fluoromethyl
group, a difluoromethyl group, a trifluoromethyl group, a
fluoroethyl group, a difluoroethyl group, a trifluoroethyl group, a
perfluoroethyl group, a fluoropropyl group, a difluoropropyl group,
a trifluoropropyl group, a pentafluoropropyl group, a
hexafluoropropyl group, a perfluoropropyl group, a fluorobutyl
group, a difluorobutyl group, a trifluorobutyl group, a
tetrafluorobutyl group, a pentafluorobutyl group, a perfluorobutyl
group, and the like.
[0163] Examples of the monovalent organic group having an alicyclic
structure represented by R.sup.r include a cyclopentyl group, a
cyclohexyl group, a 1-norbornyl group, a 2-norbornyl group, a
1-norbornenyl group, a 2-norbornenyl group, a 1-adamantyl group, a
2-adamantyl group, a furyl group and the like, and a methylene
group or an alkylene group such as an ethylene group, a propylene
group or a butylene group, to which a cyclopentyl group, a
cyclohexyl group, a 1-norbornyl group, a 2-norbornyl group, a
1-norbornenyl group, a 2-norbornenyl group, a 1-adamantyl group, a
2-adamantyl group or a furyl group bonds, and the like. Of these,
groups having a polycyclic alicyclic structure such as a norbornyl
group and an adamantyl group are preferred, and groups having an
adamantyl group are more preferred.
[0164] A part or all of hydrogen atoms included in R.sup.r are not
substituted or substituted by a substituent. Examples of the
substituent include a hydroxyl group, a carboxyl group, an
alkylcarbonyl group, a cyano group, a nitro group, a sulfonamide
group, and the like. Moreover, keto groups formed by substituting
two hydrogen atoms bonded to an identical carbon atom of R.sup.r
are also exemplified.
[0165] The monovalent organic group having an alicyclic structure
represented by R.sup.r is preferably the group represented by the
above formula (i).
[0166] In the above formula (i), A represents a linking group
having a valency of (m+1); m is an integer of 1 to 3; and R.sup.r1
represents a monovalent organic group having 3 to 20 carbon atoms
and having an alicyclic structure.
[0167] Examples of the linking group having a valency of (m+1)
represented by A include:
[0168] divalent linking groups such as an ester group, an ether
group, a carbonyl group, an amide group, an imino group, an
alkanediyl group, a cycloalkanediyl group, an arylene group and an
aralkylene group;
[0169] trivalent linking groups such as an alkanetriyl group, a
cycloalkanetriyl group and an arenetriyl group;
[0170] tetravalent linking groups such as an alkanetetrayl group, a
cycloalkanetetrayl group and an arenetetrayl group.
[0171] Examples of the monovalent organic group having 3 to 20
carbon atoms and having an alicyclic structure represented by
R.sup.r1 include those exemplified in connection with R.sup.r
described above.
[0172] The cation represented by X.sup.+ onium cations of sulfur,
iodine, phosphorus, nitrogen and the like, and specific examples
include a sulfonium cation, a tetrahydrothiophenium cation, an
iodonium cation, a phosphonium cation, a diazonium cation, a
pyridinium cation, and the like. Of these, a sulfonium cation and a
tetrahydrothiophenium cation are preferred, and a sulfonium cation
is more preferred.
[0173] Examples of preferred acid generator (B) include those
represented by the following formulae.
##STR00019## ##STR00020##
[0174] In the above formulae, X.sup.+ represents a monovalent
cation.
[0175] These acid generators (B) may be used either alone, or in
combination of two or more thereof. The amount of the acid
generator (B) employed in the case of the acid generator (B) being
the acid generating agent is typically no less than 0.1 parts by
mass and no greater than 20 parts by mass, and preferably no less
than 0.5 parts by mass and no greater than 15 parts by mass with
respect to 100 parts by mass of the polymer component (A) in view
of ensuring the sensitivity and developability for use as a resist.
In this case, when the amount of the acid generating agent (B)
employed is less than 0.1 parts by mass, the sensitivity and
developability tend to be deteriorated, whereas the amount of the
acid generating agent (B) exceeding 15 parts by mass is likely to
result in reduction of radiation transmittance, and to render the
formation of the desired resist patterns difficult.
Fluorine Atom-Containing Polymer
[0176] The radiation-sensitive resin composition may contain a
fluorine atom-containing polymer (excluding the polymer component
(A)). When the radiation-sensitive resin composition contains the
fluorine atom-containing polymer, the polymer tends to be unevenly
distributed in the vicinity of the surface of the resist coating
film in forming the resist coating film, due to an oil repellent
feature of the fluorine atom-containing polymer in the film. Thus,
elution of the acid generating agent, the acid diffusion control
agent, etc., into the liquid immersion medium during liquid
immersion lithography can be inhibited. In addition, owing to a
water repellent feature of the fluorine atom-containing polymer, an
advancing contact angle of a liquid immersion medium on a resist
coating film can be controlled to fall within a desired range,
whereby formation of bubble defects can be suppressed. Furthermore,
a receding contact angle of a liquid immersion medium on a resist
coating film increases, thereby enabling exposure by high-speed
scanning without remaining water droplets. The radiation-sensitive
resin composition thus containing the fluorine atom-containing
polymer enables a resist coating film to be formed which is
suitable for a liquid immersion lithography process.
[0177] The fluorine atom-containing polymer is not particularly
limited as long as it contains a fluorine atom, and preferably has
the content of fluorine atoms (% by mass) greater than that of the
polymer component (A). The content of fluorine atoms being greater
than that of the polymer component (A), leads to a higher degree of
uneven distribution, whereby characteristics such as water
repellency and elution-inhibiting properties the resultant resist
coating film can be improved.
[0178] The fluorine atom-containing polymer is prepared by
polymerizing one or more types of monomers that include a fluorine
atom in the structure thereof.
[0179] 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.
[0180] Examples of the monomer that gives a polymer including a
fluorine atom in its main chain include .alpha.-fluoroacrylate
compounds, .alpha.-trifluoromethyl acrylate compounds,
.beta.-fluoroacrylate compounds, .beta.-trifluoromethyl acrylate
compounds, .alpha.,.beta.-fluoroacrylate compounds,
.alpha.,.beta.-trifluoromethyl acrylate 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.
[0181] Examples of the monomer that gives a polymer including a
fluorine atom in its side chain include compounds in which an
alicyclic olefin compound such as norbornene has fluorine, a
fluoroalkyl group and/or a derivative thereof as a side chain,
ester compounds of acrylic acid or methacrylic acid with a
fluoroalkyl group and/or a derivative thereof, olefins having a
fluorine atom, a fluoroalkyl group and/or a derivative thereof as
one or more types of side chain (a site excluding a double bond),
and the like.
[0182] Examples of the monomer that gives a polymer including a
fluorine atom in its main chain and side chain include ester
compounds of .alpha.-fluoroacrylic acid, .beta.-fluoroacrylic acid,
.alpha.,.beta.-fluoroacrylic acid, .alpha.-trifluoromethyl acrylic
acid, .beta.-trifluoromethyl acrylic acid,
.alpha.,.beta.-trifluoromethylacrylic acid or the like with a
fluoroalkyl group and/or a derivative thereof, compounds 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, a
fluoroalkyl group and/or a derivative thereof; 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 and/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.
[0183] The structural unit included in the fluorine atom-containing
polymer is exemplified by a structural unit (hereinafter, may be
also referred to as "structural unit (F-I)") represented by the
following formula (F1).
##STR00021##
[0184] In the above formula (F1), R.sup.3 represents a hydrogen
atom, a fluorine atom, a methyl group or a trifluoromethyl group; E
represents a divalent linking group; and R.sup.4 represents a
linear or branched alkyl group having 1 to 6 carbon atoms, or a
monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms
or derivative groups thereof, having at least one fluorine
atoms.
[0185] Examples of the divalent linking group represented by E
include a single bond, an oxygen atom, a sulfur atom, a carbonyloxy
group, an oxycarbonyl group, an amide group, a sulfonylamide group,
a urethane group, and the like.
[0186] Examples of monomers which give the above structural unit
(F-I) 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-1-propyl ester, (meth)acrylic acid
perfluoro-n-butyl ester, (meth)acrylic acid perfluoro-1-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 the
like.
[0187] The fluorine atom-containing polymer may include only one
type or two or more types of the structural unit (F-I). The
proportion of the structural unit (F-I) included with respect to
100 mol % of the entire structural units in fluorine
atom-containing polymer 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 (F-I) included
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 suppressed.
[0188] In addition to the structural unit (F-I), the fluorine
atom-containing polymer may include at least one type of "other
structural units" such as, for example: in order to control rates
of dissolution in developer solutions, a structural unit having a
group such as an acid-labile group, a structural unit having a
lactone group, a cyclic carbonate group, a hydroxyl group or a
carboxyl group, or an alicyclic structure; and/or a structural unit
derived from an aromatic compound.
[0189] The other structural unit having an acid-labile group is
exemplified by similar structural units having an acid-labile group
exemplified in connection with the above structural unit (I) and
structural unit (II) in the polymer component (A). The other
structural unit having a lactone group and/or a cyclic carbonate
group is exemplified by similar structural units to the structural
unit (III) in the polymer component (A). The other structural unit
having a hydroxyl group is exemplified by similar structural units
having a hydroxyl group exemplified in connection with the above
structural unit (I), structural unit (II), etc., in the polymer
component (A).
[0190] The other structural unit having an alicyclic structure
(hereinafter, may be also referred to as "structural unit (F-II)")
is exemplified by a structural unit represented by the following
formula (F2).
##STR00022##
[0191] 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 an alicyclic hydrocarbon group having 4 to 20
carbon atoms.
[0192] The 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,
tricyclo[3.3.1.1.sup.3,7]decane. The cycloalkane-derived alicyclic
ring may have a substituent, and is optionally substituted with at
least one or at least one type of a linear, branched or cyclic
alkyl group having 1 to 4 carbon atoms such as, for example, 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.
[0193] Examples of monomers which give the above structural unit
(F-II) include (meth)acrylic acid bicyclo[2.2.1]hept-2-yl ester,
(meth)acrylic acid bicyclo[2.2.2]oct-2-yl ester, (meth)acrylic acid
tricyclo[5.2.1.0.sup.2,6]dec-7-yl ester, (meth)acrylic acid
tetracyclo[6.2.1.1.sup.3,6.0.sup.2,7]dodec-9-yl ester,
(meth)acrylic acid tricyclo[3.3.1.1.sup.3,7]dec-1-yl ester,
(meth)acrylic acid tricyclo[3.3.1.1.sup.3,7]dec-2-yl ester, and the
like.
[0194] The proportion of the other structural unit included in the
fluorine atom-containing polymer with respect to 100 mol % of the
entire structural units in the fluorine atom-containing polymer is
typically no greater than 80 mol %, preferably no greater than 75
mol %, and more preferably no greater than 70 mol %.
[0195] The Mw of the fluorine atom-containing polymer is preferably
1,000 to 50,000, more preferably 1,000 to 30,000, and particularly
preferably 1,000 to 10,000. When the Mw of the fluorine
atom-containing polymer is less than 1,000, it is impossible to
attain a sufficient advancing contact angle. On the other hand, the
Mw of the fluorine atom-containing polymer exceeding 50,000 is
likely to result in deteriorated developability of the resultant
resist.
[0196] A ratio of Mw to Mn (Mw/Mn) of the fluorine atom-containing
polymer is typically 1 to 3, and preferably 1 to 2.
[0197] The content of the fluorine atom-containing polymer in the
radiation-sensitive resin composition with respect to 100 parts by
mass of the polymer component (A) is preferably 0 to 50 parts by
mass, more preferably 0 to 20 parts by mass, still more preferably
1 to 10 parts by mass, and particularly preferably 2 to 8 parts by
mass. When the content of the fluorine atom-containing polymer in
the radiation-sensitive resin composition falls within the above
range, water repellency and elution-inhibiting properties of the
surface of the resultant resist coating film can be further
improved.
Synthesis Method of Fluorine Atom-Containing Polymer
[0198] The fluorine atom-containing polymer may be synthesized, for
example, by polymerizing the monomer that gives each predetermined
structural unit in an appropriate solvent using a radical
polymerization initiator.
Solvent
[0199] In general, the radiation-sensitive resin composition
contains a solvent. The solvent is not particularly limited as long
as it can dissolve or disperse at least the polymer component (A)
and the acid generator (B) described above, and optional components
added as needed. The solvent is exemplified by an alcohol solvent,
a ketone solvent, an amide solvent, an ether solvents, an ester
solvent and a mixed solvent thereof, and the like.
[0200] Examples of the alcohol solvent include:
[0201] 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, benzyl alcohol and
diacetone alcohol;
[0202] 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;
[0203] partially etherified polyhydric alcohol 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.
[0204] Examples of the ketone solvent include acetone, methyl ethyl
ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl
ketone, methyl isobutyl ketone, methyl n-pentyl ketone, ethyl
n-butyl ketone, methyl n-hexyl ketone, di-isobutyl ketone,
trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone,
cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonyl
acetone, diacetone alcohol, acetophenone, and the like.
[0205] Examples of the amide solvent include
N,N'-dimethylimidazolidinone, N-methylformamide,
N,N-dimethylformamide, N,N-diethylformamide, acetamide,
N-methylacetamide, N,N-dimethylacetamide, N-methylpropionamide,
N-methylpyrrolidone, and the like.
[0206] Examples of the ester solvent include diethyl carbonate,
propylene carbonate, methyl acetate, ethyl acetate,
.gamma.-butyrolactone, .gamma.-valerolactone, n-propyl acetate,
isopropyl acetate, n-butyl acetate, isobutyl 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,
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, dipropylene glycol
monoethyl ether acetate, diglycol acetate, methoxytriglycol
acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate,
diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate,
n-butyl lactate, n-amyl lactate, diethyl malonate, dimethyl
phthalate, diethyl phthalate, and the like.
[0207] Examples of the other solvent include:
[0208] 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;
[0209] aromatic hydrocarbon solvents such as benzene, toluene,
xylene, mesitylene, ethylbenzene, trimethylbenzene,
methylethylbenzene, n-propylbenzene, isopropylbenzene,
diethylbenzene, isobutylbenzene, triethylbenzene,
di-isopropylbenzene and n-amylnaphthalene;
[0210] halogen-containing solvents such as dichloromethane,
chloroform, chlorofluorocarbon, chlorobenzene and
dichlorobenzene;
[0211] carbonate ester solvents such as ethylene carbonate and
propylene carbonate, and the like.
[0212] Of these solvents, ester solvents and ketone solvents are
preferred, and propylene glycol monomethyl ether acetate,
cyclohexanone and .gamma.-butyrolactone are more preferred. These
solvents may be used either alone, or in combination of two or more
thereof.
Acid Diffusion Controller
[0213] The acid diffusion controller exerts the effect of
controlling diffusion phenomenon of the acid generated from the
acid generator (B) upon the exposure in the resist coating film,
and suppressing unfavorable chemical reactions in unexposed
regions; as a result, storage stability of the resultant
radiation-sensitive resin composition is further improved, and
resolution of the resist is further improved, while suppressing
variation of line width of the resist pattern caused by variation
of post-exposure delay (PED) from the exposure until a development
treatment, which enables the radiation-sensitive resin composition
with superior process stability to be obtained. The mode of
incorporation of the acid diffusion controller into the
radiation-sensitive resin composition may be in a free compound
form (hereinafter, may be referred to as "acid diffusion control
agent", as appropriate) or in an incorporated form as a part of the
polymer, or in both of these forms.
[0214] Examples of the acid diffusion control agent include amine
compounds, amide group-containing compounds, urea compounds,
nitrogen-containing heterocyclic compounds, and the like.
[0215] Examples of the amine compounds include
mono(cyclo)alkylamines; di(cyclo)alkylamines;
tri(cyclo)alkylamines; substituted alkylaniline or 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, 2-quinoxalinol,
N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine,
N,N,N',N''N''-pentamethyldiethylenetriamine, and the like.
[0216] Examples of the amide group-containing compound include
N-t-butoxycarbonyl group-containing amino compounds, formamide,
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.
[0217] Examples of the urea compounds include urea, methylurea,
1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea,
1,3-diphenylurea, tri-n-butylthiourea, and the like.
[0218] Examples of the nitrogen-containing heterocyclic compounds
include imidazoles; pyridines; piperazines; pyrazine, pyrazole,
pyridazine, quinoxaline, purine, pyrrolidine, piperidine,
piperidine ethanol, 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.
[0219] In addition, the acid diffusion control agent may be a
photodegradable base which is sensitized upon exposure to generate
a weak acid. An example of the photodegradable base includes onium
salt compounds which degrade upon the exposure and lose their acid
diffusion controllability. Examples of the onium salt compounds
include sulfonium salt compounds represented by the following
formula (D1), and iodonium salt compounds represented by the
following formula (D2).
##STR00023##
[0220] In the above formulae (D1) and (D2), R.sup.6 to R.sup.10
each independently represent a hydrogen atom, an alkyl group, an
alkoxyl group, a hydroxyl group or a halogen atom; Z.sup.-
represents OH.sup.-, R.sup.D--COO.sup.- or R.sup.D--SO.sub.3.sup.-,
wherein R.sup.D represents an alkyl group, an aryl group, an
alkaryl group or an anion represented by the following formula
(D3).
##STR00024##
[0221] In the above formula (D3), 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 above alkyl group and
alkoxyl group are not substituted or substituted by a fluorine
atom; and u is an integer of 0 to 2.
[0222] The content of the acid diffusion control agent is
preferably less than 5 parts by mass with respect to 100 parts by
mass of the polymer component (A). When the total amount used
exceeds 5 parts by mass, sensitivity as a resist tends to be
deteriorated.
Alicyclic Skeleton Compound
[0223] The alicyclic skeleton compound is a component which exerts
the effect of further improving dry etching resistance, pattern
configuration, adhesiveness to a substrate, and the like. Examples
of the alicyclic skeleton compound include adamantane derivatives
such as 1-adamantanecarboxylic acid, 2-adamantanone and t-butyl
1-adamantanecarboxylate; deoxycholic acid esters such as t-butyl
deoxycholate, t-butoxycarbonylmethyl deoxycholate and 2-ethoxyethyl
deoxycholate; lithocholic acid esters such as t-butyl lithocholate,
t-butoxycarbonylmethyl lithocholate and 2-ethoxyethyl lithocholate;
3-[2-hydroxy-2,2-bis(trifluoromethyl)ethyl]tetracyclo[4.4.0.1.sup.2,5.1.s-
up.7,10]dodecane,
2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo[4.2.1.0.sup.3,7]nonane,
and the like.
Surfactant
[0224] The surfactant is a component which has the effect of
improving coating property, striation, developability and the like.
Examples of the surfactant include nonionic surfactants such as
polyoxyethylene lauryl ether, polyoxyethylene stearyl ether,
polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether,
polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate,
polyethylene glycol distearate, as well as in terms of trade names,
KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.); POLYFLOW No.
75, and No. 95 (each manufactured by Kyoeisha Chemical Co., Ltd.);
F-top EF301, EF303, and EF352 (each manufactured by Tochem Products
Co. Ltd.); Megafac F171, and F173 (each manufactured by Dainippon
Ink And Chemicals, Incorporated); Fluorad FC430, and FC431 (each
manufactured by Sumitomo 3M Ltd.); AsahiGuard AG 710, Surflon
S-382, SC-101, SC-102, SC-103, SC-104, SC-105, and SC-106 (each
manufactured by Asahi Glass Co., Ltd.), and the like. These
surfactants may be used either alone, or in combination of two or
more thereof.
Sensitizing Agent
[0225] The sensitizing agent exhibits the action of absorbing an
energy of a radioactive ray and transfers the energy to the acid
generating agent (A), thereby increasing the amount of the acid
produced, and thus has the effect of improving "apparent
sensitivity" of the radiation-sensitive resin composition. Examples
of the sensitizing agent include carbazoles, acetophenones,
benzophenones, naphthalenes, phenols, biacetyls, eosins, rose
bengals, pyrenes, anthracenes, phenothiazines, and the like.
Preparation of Radiation-Sensitive Resin Composition
[0226] The radiation-sensitive resin composition may be prepared by
mixing, for example, the polymer component (A), the acid generator
(B) and the optional component(s) at a certain ratio. Also, it is
possible to prepare the radiation-sensitive resin composition in a
state of being dissolved or dispersed in an appropriate organic
solvent. The organic solvent is not particularly limited and may be
any one exemplified as the solvent above, as long as it can
dissolve or disperse the polymer component (A), the acid generating
agent (B), and the optional component(s). The radiation-sensitive
resin composition is usually prepared upon use by dissolving in a
solvent, and thereafter filtering the obtained mixture through a
filter having a pore size of about 0.20 .mu.m, for example.
Radiation-Sensitive Resin Composition
[0227] The radiation-sensitive resin composition of the embodiment
of the present invention is for use in
[0228] a resist pattern-forming method carried out using a
developer solution containing no less than 80% by mass of an
organic solvent, the radiation-sensitive resin composition
containing:
[0229] (A) a polymer component including a polymer having an
acid-labile group; and
[0230] (B) a radiation-sensitive acid generator,
[0231] the polymer component (A) including, in an identical polymer
or different polymers, (I) a structural unit having (a1) a
hydrocarbon group, and (II) a structural unit having (a2) a
hydrocarbon group,
[0232] the hydrocarbon group (a1) being a unsubstituted or
substituted branched chain group having no greater than 8 carbon
atoms or an unsubstituted or substituted monocyclic alicyclic group
having 3 to 8 carbon atoms,
[0233] the hydrocarbon group (a2) having an adamantane
skeleton,
[0234] a molar ratio of the hydrocarbon group (a2) to the
hydrocarbon group (a1) being less than 1, and
[0235] a proportion of the structural unit having a hydroxyl group
in the polymer component (A) being less than 5 mol %.
[0236] Use of the radiation-sensitive resin composition for a
resist pattern-forming method carried out using a developer
solution containing no less than 80% by mass of an organic solvent
enables a resist pattern capable of achieving both superior etching
resistance and inhibition of the film loss of a resist coating
film, and being superior in lithography characteristics such as CDU
to be obtained. Since the radiation-sensitive resin composition is
described in connection with the Resist Pattern-Forming Method
above, the explanation in this section is omitted.
EXAMPLES
[0237] Hereinafter, the present invention will be explained more
specifically by way of Examples, but the present invention is not
limited to these Examples. Methods of the determination of various
types of physical property values are shown below.
Weight Average Molecular Weight (Mw) and Number Average Molecular
Weight (Mn)
[0238] The Mw and the Mn of the polymer were determined by gel
permeation chromatography (GPC) using GPC columns ("G2000
HXL".times.2, "G3000 HXL.times.1, "G4000 HXL".times.1) manufactured
by Tosoh Corporation under the following conditions.
[0239] eluent: tetrahydrofuran (manufactured by Wako Pure Chemical
Industries, Ltd.)
[0240] flow rate: 1.0 mL/min
[0241] sample concentration: 1.0% by mass
[0242] amount of injected sample: 100 .mu.L
[0243] detector: differential refractometer
[0244] standard substance: mono-dispersed polystyrene
.sup.13C-NMR Analysis:
[0245] The analysis was carried out using "JNM-EX400" manufactured
by JEOL, Ltd., with DMSO-d.sub.6 for use as a solvent for
measurement.
Synthesis of Polymer Component (A)
[0246] Monomers used in synthesis of the polymers constituting the
polymer component (A), and the fluorine atom-containing polymer
described later are shown below.
##STR00025## ##STR00026## ##STR00027##
Synthesis Example 1
[0247] A monomer solution was prepared by dissolving 28.4 g (35 mol
%) of the compound (M-1), 18.0 g (15 mol %) of the compound (M-10)
and 53.6 g (50 mol %) of the compound (M-16) in 200 g of
2-butanone, and then adding thereto 2.38 g (3 mol %) of AIBN. A
1,000 mL three-necked flask charged with 100 g of 2-butanone was
purged with nitrogen for 30 minutes, and thereafter heated to
80.degree. C. with stirring. The monomer solution prepared was
added dropwise using a dropping funnel over 3 hrs. The time when
dropwise addition was started was assumed to be a start time point
of the polymerization reaction, and the polymerization reaction was
carried out for 6 hours. After completion of the polymerization
reaction, the polymerization solution was cooled to no greater than
30.degree. C. by water-cooling. The cooled polymerization solution
was charged into 2,000 g of methanol, and the white powder
precipitated was filtered off. Thus resultant white powder was
washed twice with 400 g of methanol, and thereafter filtered off
and dried at 50.degree. C. for 17 hrs to obtain a polymer (A-1) in
the form of a white powder (yield: 81%). The polymer (A-1) had the
Mw of 9,830, the Mw/Mn of 1.47, and the content of fluorine atoms
of 0.0%. In addition, as a result of the .sup.13C-NMR analysis, the
polymer (A-1) was verified to be a copolymer including the
structural unit derived from the compound (M-1), the structural
unit derived from the compound (M-10) and the structural unit
derived from the compound (M-16) at each proportion of
33.0:12.9:54.1 (mol %). Furthermore, a molar ratio of the
hydrocarbon group (a2) to the hydrocarbon group (a1) in the polymer
(A-1) was 0.391.
Synthesis Examples 2 to 19
[0248] Polymers (A-2) to (A-11), and (CA-1) to (CA-8) were obtained
in a similar manner to Synthesis Example 1 except that each monomer
compound of the type and the amount shown in Tables 1-1 and 1-2 was
used. Further, the content of the structural unit derived from each
monomer and the molar ratio of the hydrocarbon group (a2) to the
hydrocarbon group (a1) in each polymer obtained, and measurements
of Mw and Mw/Mn ratio of each polymer are shown in Tables 2-1 and
2-2.
TABLE-US-00001 TABLE 1-1 Proportion of monomer-charged Structural
unit (II) Structural unit not containing containing Structural unit
Other structural (I) hydroxyl group hydroxyl group (III) unit
Polymer monomer mol % monomer mol % monomer mol % monomer mol %
monomer mol % Synthesis A-1 M-1 35 M-10 15 -- -- M-16 50 -- --
Example 1 Synthesis A-2 M-2 45 M-11 10 -- -- M-16 45 -- -- Example
2 Synthesis A-3 M-3 35 M-12 25 -- -- M-16 40 -- -- Example 3
Synthesis A-4 M-5 30 M-10 17 M-13 3 M-16 50 -- -- Example 4
Synthesis A-5 M-6 45 M-9 25 -- -- M-16 20 -- -- Example 5 M-17 10
Synthesis A-6 M-7 30 M-10 10 -- -- M-16 45 -- -- Example 6 M-15 15
Synthesis A-7 M-4 40 M-9 15 M-14 3 M-16 42 -- -- Example 7
Synthesis A-8 M-3 40 M-15 20 -- -- M-16 30 -- -- Example 8 M-8 10
Synthesis A-9 M-3 45 M-12 15 -- -- M-16 40 -- -- Example 9
Synthesis A-10 M-6 45 M-12 15 -- -- M-16 40 -- -- Example 10
TABLE-US-00002 TABLE 1-2 Proportion of monomer-charged Structural
unit (II) Structural unit not containing containing Structural unit
Other structural (I) hydroxyl group hydroxyl group (III) unit
Polymer monomer mol % monomer mol % monomer mol % monomer mol %
monomer mol % Synthesis A-11 M-2 45 M-12 15 -- -- M-16 40 -- --
Example 11 Synthesis CA-1 M-1 50 -- -- -- -- M-16 50 -- -- Example
12 Synthesis CA-2 -- -- M-9 50 -- -- M-16 50 -- -- Example 13
Synthesis CA-3 M-2 15 M-9 35 -- -- M-16 50 -- -- Example 14
Synthesis CA-4 M-5 25 M-11 20 M-13 15 M-16 40 -- -- Example 15
Synthesis CA-5 M-3 40 -- -- M-13 20 M-16 40 -- -- Example 16
Synthesis CA-6 M-1 35 -- -- -- -- M-16 50 M-19 15 Example 17
Synthesis CA-7 M-1 35 -- -- -- -- M-16 50 M-20 15 Example 18
Synthesis CA-8 -- -- M-10 15 -- -- M-16 50 M-21 35 Example 19
TABLE-US-00003 TABLE 2-1 Molar ratio Proportion of Structural unit
included of Structural unit (II) Other hydrocarbon Structural not
containing containing Structural structural group (a2) unit (I)
hydroxyl group hydroxyl group unit (III) unit to mol mol mol mol
mol hydrocarbon Polymer monomer % monomer % monomer % monomer %
monomer % group (a1) Mw Mw/Mn Synthesis A-1 M-1 33.0 M-10 12.9 --
-- M-16 54.1 -- -- 0.391 9,830 1.47 Example 1 Synthesis A-2 M-2
41.2 M-11 7.1 -- -- M-16 51.7 -- -- 0.172 10,150 1.45 Example 2
Synthesis A-3 M-3 32.4 M-12 25.2 -- -- M-16 42.4 -- -- 0.778 9,020
1.48 Example 3 Synthesis A-4 M-5 27.9 M-10 13.0 M-13 2.6 M-16 56.5
-- -- 0.559 10,040 1.51 Example 4 Synthesis A-5 M-6 41.8 M-9 23.3
-- -- M-16 8.9 -- -- 0.557 9,560 1.49 Example 5 M-17 26.0 Synthesis
A-6 M-7 27.1 M-10 8.1 -- -- M-16 51.4 -- -- 0.793 9,250 1.50
Example 6 M-15 13.4 Synthesis A-7 M-4 36.9 M-9 14.0 M-14 2.4 M-16
46.7 -- -- 0.444 9,430 1.48 Example 7 Synthesis A-8 M-3 38.1 M-15
18.1 -- -- M-16 34.6 -- -- 0.383 9,860 1.51 Example 8 M-8 9.2
Synthesis A-9 M-3 43.0 M-12 15.6 -- -- M-16 41.4 -- -- 0.363 9,320
1.49 Example 9
TABLE-US-00004 TABLE 2-2 Molar ratio Proportion of Structural unit
included of Structural unit (II) Other hydrocarbon Structural not
containing containing Structural structural group (a2) unit (I)
hydroxyl group hydroxyl group unit (III) unit to Poly- mol mol mol
mol mol hydrocarbon mer monomer % monomer % monomer % monomer %
monomer % group (a1) Mw Mw/Mn Synthesis A-10 M-6 43.5 M-12 15.3 --
-- M-16 41.2 -- -- 0.352 9,280 1.48 Example 10 Synthesis A-11 M-2
42.7 M-12 15.7 -- -- M-16 41.6 -- -- 0.368 9,340 1.49 Example 11
Synthesis CA-1 M-1 47.0 -- -- -- -- M-16 53.0 -- -- -- 10,420 1.52
Example 12 Synthesis CA-2 -- -- M-9 47.6 -- -- M-16 52.4 -- -- --
8,670 1.46 Example 13 Synthesis CA-3 M-2 13.5 M-9 34.0 -- -- M-16
52.5 -- -- 2.519 9,340 1.49 Example 14 Synthesis CA-4 M-5 23.1 M-11
18.6 M-13 14.2 M-16 44.1 -- -- 1.420 9,520 1.52 Example 15
Synthesis CA-5 M-3 38.5 -- -- M-13 20.6 M-16 41.9 -- -- 0.535 9,480
1.48 Example 16 Synthesis CA-6 M-1 33.4 -- -- -- -- M-16 53.5 M-19
13.1 0.392 9,740 1.46 Example 17 Synthesis CA-7 M-1 33.6 -- -- --
-- M-16 53.4 M-20 13.0 0.387 9,910 1.48 Example 18 Synthesis CA-8
-- -- M-10 14.1 -- -- M-16 50.7 M-21 35.2 0.401 9,740 1.49 Example
19
Synthesis of Fluorine Atom-Containing Polymer
Synthesis Example 20
[0249] A monomer solution was prepared by dissolving 35.8 g (70 mol
%) of the compound (M-2) and 14.2 g (30 mol %) of the compound
(M-18) in 100 g of 2-butanone, and then adding thereto 2.34 g of
dimethyl 2,2'-azobisisobutyrate. A 500 mL three-necked flask
charged with 20 g of 2-butanone was purged with nitrogen for 30
minutes, and thereafter heated to 80.degree. C. with stirring. The
monomer solution prepared was added dropwise using a dropping
funnel over 3 hrs. The time when dropwise addition was started was
assumed to be a start time point of the polymerization reaction,
and the polymerization reaction was carried out for 6 hours. After
completion of the polymerization reaction, the polymerization
solution was cooled to no greater than 30.degree. C. by
water-cooling. The reaction solution was transferred to a 1 L
separatory funnel, then homogenously diluted with 200 g of
n-hexane, and 800 g of methanol was charge thereto followed by
mixing. Subsequently, 20 g of distilled water was charged, and the
mixture was further stirred and allowed to stand for 30 min.
Thereafter, the under layer was recovered to give a polymer (C-1)
in a propylene glycol monomethyl ether acetate solution (yield:
60%). The polymer (C-1) had the Mw of 6,000, and the Mw/Mn of 1.45.
In addition, as a result of the .sup.13C-NMR analysis, the polymer
(C-1) was verified to be a copolymer including the structural unit
derived from the compound (M-2) and the structural unit derived
from the compound (M-18) at each proportion of 69:31 (mol %).
Preparation of Radiation-Sensitive Resin Composition
[0250] The acid generating agent (B), the acid diffusion control
agent and the solvent used in preparation of the
radiation-sensitive resin compositions are shown below.
(B) Acid Generating Agent
[0251] B-1: triphenylsulfonium
6-adamantylcarbonyloxy-1,1,2,2-tetrafluorohexanesulfonate (compound
represented by the following formula (B-1)) [0252] B-2:
triphenylsulfonium 2-adamantyl-1,1-difluoroethanesulfonate
(compound represented by the following formula (B-2))
##STR00028##
[0252] Acid Diffusion Control Agent
[0253] D-1: t-pentyl 4-hydroxypyridine-N-carboxylate (compound
represented by the following formula (D-1)) [0254] D-2:
triphenylsulfonium salicylate (compound represented by the
following formula (D-2)) [0255] D-3: triphenylsulfonium
camphorsulfonate (compound represented by the following formula
(D-3))
##STR00029##
[0255] Solvent
[0256] E-1: propylene glycol monomethyl ether acetate [0257] E-2:
cyclohexanone [0258] E-3: .gamma.-butyrolactone
Example 1
[0259] A radiation-sensitive resin composition (J-1) was prepared
by mixing 100 parts by mass of the polymer (A-1), 3 parts by mass
of the polymer (C-1), 11 parts by mass of the acid generating agent
(B-1), 4.5 parts by mass of the acid diffusion control agent (D-1),
and as the solvent 1,620 parts by mass of (E-1), 700 parts by mass
of (E-2) and 30 parts by mass of (E-3), and then filtering the
obtained mixture through a filter having a pore size of 0.2
.mu.m.
Examples 2 to 13, and Synthesis Examples 21 to 28
[0260] Radiation-sensitive resin compositions were prepared in a
similar manner to Example 1 except that each component of the type
and the amount shown in Tables 3-1 and 3-2 was used.
TABLE-US-00005 TABLE 3-1 Fluorine (B) Acid atom- Acid Radiation-
generating containing diffusion sensitive (A) Component agent
polymer control agent Solvent resin parts parts parts parts parts
composition type by mass type by mass type by mass type by mass
type by mass Example 1 J-1 A-1 100 B-1 11 C-1 3 D-2 4.5 E-1/E-2/E-3
1,620/700/30 Example 2 J-2 A-1 100 B-2 8.5 C-1 3 D-3 4.5
E-1/E-2/E-3 1,620/700/31 Example 3 J-3 A-1 100 B-1 11 C-1 3 D-1 1
E-1/E-2/E-3 1,620/700/32 Example 4 J-4 A-2 100 B-1 11 C-1 3 D-2 4.5
E-1/E-2/E-3 1,620/700/33 Example 5 J-5 A-3 100 B-1 11 C-1 3 D-2 4.5
E-1/E-2/E-3 1,620/700/34 Example 6 J-6 A-4 100 B-1 11 C-1 3 D-2 4.5
E-1/E-2/E-3 1,620/700/35 Example 7 J-7 A-5 100 B-1 11 C-1 3 D-2 4.5
E-1/E-2/E-3 1,620/700/36 Example 8 J-8 A-6 100 B-1 11 C-1 3 D-2 4.5
E-1/E-2/E-3 1,620/700/37 Example 9 J-9 A-7 100 B-1 11 C-1 3 D-2 4.5
E-1/E-2/E-3 1,620/700/38 Example 10 J-10 A-8 100 B-1 11 C-1 3 D-2
4.5 E-1/E-2/E-3 1,620/700/39 Example 11 J-11 A-9 100 B-2 8.5 C-1 3
D-3 4.5 E-1/E-2/E-3 1,620/700/40 Example 12 J-12 A-10 100 B-2 8.5
C-1 3 D-3 4.5 E-1/E-2/E-3 1,620/700/41 Example 13 J-13 A-11 100 B-2
8.5 C-1 3 D-3 4.5 E-1/E-2/E-3 1,620/700/42
TABLE-US-00006 TABLE 3-2 Fluorine (B) Acid atom- Acid Radiation-
(A) generating containing diffusion sensitive Component agent
polymer control agent Solvent resin parts parts parts parts parts
composition type by mass type by mass type by mass type by mass
type by mass Synthesis CJ-1 CA-1 100 B-1 11 C-1 3 D-2 4.5
E-1/E-2/E-3 1,620/700/43 Example 21 Synthesis CJ-2 CA-2 100 B-1 11
C-1 3 D-2 4.5 E-1/E-2/E-3 1,620/700/44 Example 22 Synthesis CJ-3
CA-3 100 B-1 11 C-1 3 D-2 4.5 E-1/E-2/E-3 1,620/700/45 Example 23
Synthesis CJ-4 CA-4 100 B-1 11 C-1 3 D-2 4.5 E-1/E-2/E-3
1,620/700/46 Example 24 Synthesis CJ-5 CA-5 100 B-1 11 C-1 3 D-2
4.5 E-1/E-2/E-3 1,620/700/47 Example 25 Synthesis CJ-6 CA-6 100 B-1
11 C-1 3 D-2 4.5 E-1/E-2/E-3 1,620/700/48 Example 26 Synthesis CJ-7
CA-7 100 B-1 11 C-1 3 D-2 4.5 E-1/E-2/E-3 1,620/700/49 Example 27
Synthesis CJ-8 CA-8 100 B-1 11 C-1 3 D-2 4.5 E-1/E-2/E-3
1,620/700/50 Example 28
Formation of Resist Pattern
Example 14
[0261] On a 12-inch silicon wafer which had been provided with an
underlayer antireflective film (ARC66, manufactured by Nissan
Chemical Industries, Ltd.) having a film thickness of 105 nm, a
coating film having a film thickness of 100 nm was provided using
the radiation-sensitive resin composition prepared in Example 1,
and then soft baking was carried out at 80.degree. C. for 60 sec.
Next, the coating film was exposed through a mask pattern by which
a pattern provided after reduction projection had a dot of 55 nm
and a pitch of 110 nm under conditions involving NA of 1.3, iNA of
1.27 and a ratio of 0.800, with Quadrupole, using an ArF excimer
laser liquid immersion scanner (NSR S610C, manufactured by NIKON
Corporation). After the exposure, post-exposure baking (PEB) was
carried out at 100.degree. C. for 60 sec. Subsequently, the film
was developed with butyl acetate at 23.degree. C. for 30 sec, and
subjected to a rinse treatment with a 4-methyl-2-pentanol solvent
for 10 sec and dried to obtain a resist pattern. In accordance with
this procedure, an exposure dose at which the area through a mask
pattern, which yields a pattern with a dot of 55 nm and a pitch of
110 nm after reduction projection, forms a hole pattern with a
diameter of 55 nm was defined as an optimum exposure dose (Eop). It
is to be noted that a scanning electron microscope (CG-4000,
manufactured by Hitachi High-Technologies Corporation) was used for
line-width measurement.
Examples 15 to 26, and Comparative Examples 1 to 8
[0262] Resist patterns were formed in a similar manner to Example
14 except that each radiation-sensitive resin composition prepared
in Examples and Comparative Examples was used in Example 14, and
the temperature of PEB was as shown in Tables 4-1 and 4-2.
Evaluations
[0263] Film loss amount of the resist coating film was evaluated on
a resist coating film formed according to the following method. In
addition, CDU, MEEF, resolution and etching resistance were
evaluated on the resist pattern formed in Examples 14 to 26 and
Comparative Examples 1 to 7 according to the following method. The
results are shown in Tables 4-1 and 4-2.
Film Loss Amount
[0264] First, an 8-inch silicon wafer which had been provided with
an underlayer antireflective film (ARC29A, manufactured by Brewer
Science, Inc.) having an film thickness of 77 nm, a coating film
having an initial film thickness of 150 nm was provided using each
of the radiation-sensitive resin compositions prepared in Examples
and Comparative Examples, and then soft baking (SB) was carried out
at 90.degree. C. for 60 sec. Next, the entire face of the wafer was
exposed at the optimum exposure dose (Eop) (unit: mJ/cm.sup.2) that
allows a hole pattern having a diameter of 55 nm to be formed,
without using a mask under conditions involving NA of 0.78 and
sigma of 0.90, with Conventional, using an ArF excimer laser
scanner (NSR S306C, manufactured by NIKON Corporation). After the
exposure, PEB was carried out at a temperature shown in Tables 4-1
and 4-2 for 60 sec. Subsequently, the film was developed with butyl
acetate at 23.degree. C. for 30 sec, and subjected to a rinse
treatment with 4-methyl-2-pentanol for 10 sec and dried. The film
thickness of remaining coating films after completion of a series
of process was measured, and a value obtained by reducing the
remaining film thickness from the initial film thickness was
defined as a film loss amount (unit: nm). It is to be noted that
the film thickness was measured using an optical interferometric
film thickness measurement system ("Lambda Ace", manufactured by
Dainippon Screen Mfg. Co., Ltd.). With respect to the determined
film loss amount, evaluation was made as: "A" when the value was
less than 20 nm; and "B" when the value was no less than 20 nm. The
values of the film loss amount obtained and the evaluations are
shown in Tables 4-1 and 4-2 below.
CDU (Critical Dimension Uniformity)
[0265] A total of 30 hole patterns having a diameter of 55 nm
formed at the Eop as defined above in pattern formation of each of
Examples and Comparative Examples were subjected to line-width
measurement, and an average deviation of the measurement values
obtained in the line-width measurement of the total of 30 hole
patterns was calculated. Thus, CDU was determined by multiplication
of the average deviation by three. With respect to the CDU values,
evaluation was made as: "A" when the CDU value was less than 2.5;
"B" when the CDU value was no less than 2.5 and less than 3.0; and
"C" when the CDU value was no less than 3.0. The values of CDU
obtained and the evaluations are shown in Tables 4-1 and 4-2
below.
MEEF (Mask Error Enhancement Factor)
[0266] In a similar manner to resist pattern formation of each of
Examples and Comparative Examples, holes were formed on the resist
coating film using a portion of a mask pattern that yield a dot
diameter of 51 nm, 53 nm, 55 nm, 57 nm or 59 nm of the pattern
after reduction projection, at the Eop as defined above. The
diameters (nm) were plotted along the ordinate with respect to the
size (nm) of the mask pattern along abscissa. A straight line was
obtained, and the slope of the straight line was determined as
MEEF. The MEEF value (slope of the straight line) more approximate
to 1 indicates more favorable mask reproducibility. With respect to
the MEEF values, evaluation was made as: "A" when the MEEF value
was less than 3.5; "B" when the MEEF value was no less than 3.5 and
less than 4.5; and "C" when the MEEF value was no less than 4.5.
The MEEF values obtained and the evaluations are shown in Tables
4-1 and 4-2 below.
Resolution
[0267] In resist pattern formation of each of the Examples and
Comparative Examples, an exposure was carried out through a mask
pattern that yield a pattern having a dot of 55 nm and a pitch of
110 nm after the reduction projection at an exposure dose that is
no less than the Eop. The minimum dimension of the hole pattern
obtained with an increasing of the exposure dose was determined,
which was employed for evaluation of the resolution (unit: nm).
Evaluation was made as: "A" when the minimum dimension was less
than 48 nm; and "B" when the minimum dimension was no less than 48
nm. The resolutions obtained and the evaluations are shown in
Tables 4-1 and 4-2 below.
Etching Resistance
[0268] An organic antireflective film-forming agent (ARC66,
manufactured by Nissan Chemical Industries, Ltd.) was coated on the
surface of a wafer to provide an organic antireflective film having
a film thickness of 105 nm. Each of the radiation-sensitive resin
compositions of Examples and Synthesis Examples was coated on the
surface of the substrate by spin coating using CLEAN TRACK (ACT12,
manufactured by Tokyo Electron Limited), and then soft baking was
carried out on a to hot plate at 90.degree. C. for 60 sec to form a
resist coating film having a film thickness of 0.10 .mu.m.
Subsequently, the surface of the wafer was exposed at an exposure
dose corresponding to three times the optimum exposure dose (Eop)
that leads to formation of the hole pattern having a diameter of 55
nm on the resist coating film on the substrate. After the exposure,
PEB was carried out at a temperature shown in Tables 4-1 and 4-2
for 60 sec. Subsequently, the film was developed with butyl acetate
at 23.degree. C. for 30 sec, and subjected to a rinse treatment
with 4-methyl-2-pentanol for 10 sec and dried. Thereafter, each
etching rate was measured on the resist coating film before the
exposure, and on the resist coating film after completion of a
series of process until the rinse treatment finished. The
difference between the etching rate of the resist coating film
after completion of the series of process and the etching rate of
the resist coating film before subjecting to exposure was
determined. Evaluation was made as: "A" when the difference
accounted for no greater than 10% of the etching rate of the resist
coating film before subjecting to the exposure; and as "B" when the
difference accounted for no greater than 10%. The values of the
difference of the etching rates obtained and the evaluations are
shown in Tables 4-1 and 4-2 below. The measurement of the etching
rate of the resist coating film was carried out using an etching
system (manufactured by Telius, Tokyo Electron Limited), under the
following etching conditions.
[0269] flow rate of CF.sub.4 gas: 150 sccm
[0270] chamber pressure: 100 mTorr
[0271] power: 300 W (upper)/300 W (bottom)
[0272] time: 20 sec
TABLE-US-00007 TABLE 4-1 Results of evaluation Radiation- Tem- Film
loss Etching sensitive perature amount CDU MEEF Resolution
resistance resin (A) of PEB Eop value evalu- evalu- value evalu-
value evalu- composition Component (.degree. C.) (mJ/cm.sup.2) (nm)
evaluation value ation value ation (nm) ation (%) ation Example 14
J-1 A-1 100 18 17 A 2.0 A 3.7 B 38 A 8.5 A Example 15 J-2 A-1 100
25.5 17 A 1.9 A 3.9 B 37 A 8.5 A Example 16 J-3 A-1 100 18.5 17 A
2.3 A 3.8 B 41 A 8.5 A Example 17 J-4 A-2 85 19 16 A 2.1 A 3.4 A 39
A 8.0 A Example 18 J-5 A-3 80 16.5 18 A 2.2 A 4.0 B 40 A 7.5 A
Example 19 J-6 A-4 95 17.5 16 A 2.5 B 4.2 B 41 A 8.0 A Example 20
J-7 A-5 85 18.5 19 A 2.2 A 4.3 B 46 A 7.5 A Example 21 J-8 A-6 80
15.5 19 A 1.9 A 4.1 B 40 A 7.0 A Example 22 J-9 A-7 105 17 17 A 2.8
B 3.3 A 44 A 8.5 A Example 23 J-10 A-8 85 18.5 17 A 2.3 A 3.4 A 40
A 9.0 A Example 24 J-11 A-9 85 23 17 A 2.0 A 3.6 B 38 A 8.0 A
Example 25 J-12 A-10 85 24 17 A 2.0 A 3.4 A 38 A 8.0 A Example 26
J-13 A-11 95 21.5 17 A 2.1 A 3.8 B 37 A 8.0 A
TABLE-US-00008 TABLE 4-2 Results of evaluation Radiation- Tem- Film
loss Etching sensitive perature amount CDU MEEF Resolution
resistance resin (A) of PEB Eop value evalu- evalu- value evalu-
value evalu- composition Component (.degree. C.) (mJ/cm.sup.2) (nm)
evaluation value ation value ation (nm) ation (%) ation Comparative
CJ-1 CA-1 105 18.5 15 A 2.2 A 3.5 B 39 A 14.5 B Example 1
Comparative CJ-2 CA-2 115 resolution of 55 nm hole pattern failed
6.0 A Example 2 Comparative CJ-3 CA-3 105 20.5 26 B 3.8 C 5.1 C 53
B 7.0 A Example 3 Comparative CJ-4 CA-4 90 19.5 22 B 3.2 C 4.9 C 49
B 7.5 A Example 4 Comparative CJ-5 CA-5 90 20 22 B 3.1 C 4.2 B 46 A
8.5 A Example 5 Comparative CJ-6 CA-6 100 17 17 A 2.3 A 3.7 B 40 A
11.5 B Example 6 Comparative CJ-7 CA-7 100 20 19 A 2.8 B 3.9 B 49 B
8.0 A Example 7 Comparative CJ-8 CA-8 80 17 18 A 2.7 B 4.7 C 48 B
8.5 A Example 8
[0273] As is clear from Tables 4-1 and 4-2, according to the resist
pattern-forming method of the embodiment of the present invention,
both superior etching resistance and inhibition of the film loss of
a resist coating film can be achieved, and a resist pattern
superior in lithography characteristics such as CDU, MEEF,
resolution can be obtained.
[0274] According to the embodiment of the present invention, a
resist pattern-forming method capable of achieving both superior
etching resistance and inhibition of the film loss of a resist
coating film, and being superior in lithography characteristics
such as CDU can be provided, and also provided is a
radiation-sensitive resin composition suited for the resist
pattern-forming method.
[0275] 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.
* * * * *