U.S. patent application number 12/578503 was filed with the patent office on 2010-02-18 for pattern forming method, and resist composition, developer and rinsing solution used in the pattern forming method.
This patent application is currently assigned to FUJIFILM Corporaion. Invention is credited to Wataru HOSHINO, Kazuyoshi MIZUTANI, Shinji TARUTANI, Hideaki TSUBAKI, Kenji WADA.
Application Number | 20100040971 12/578503 |
Document ID | / |
Family ID | 39875492 |
Filed Date | 2010-02-18 |
United States Patent
Application |
20100040971 |
Kind Code |
A1 |
TARUTANI; Shinji ; et
al. |
February 18, 2010 |
PATTERN FORMING METHOD, AND RESIST COMPOSITION, DEVELOPER AND
RINSING SOLUTION USED IN THE PATTERN FORMING METHOD
Abstract
A pattern forming method comprising a step of applying a resist
composition whose solubility in a negative tone developer decreases
upon irradiation with an actinic ray or radiation and which
contains a resin having an alicyclic hydrocarbon structure and a
dispersity of 1.7 or less and being capable of increasing the
polarity by the action of an acid, an exposure step, and a
development step using a negative tone developer; a resist
composition for use in the method; and a developer and a rinsing
solution for use in the method, are provided, whereby a pattern
with reduced line edge roughness and high dimensional uniformity
can be formed.
Inventors: |
TARUTANI; Shinji; (Shizuoka,
JP) ; TSUBAKI; Hideaki; (Shizuoka, JP) ;
MIZUTANI; Kazuyoshi; (Shizuoka, JP) ; WADA;
Kenji; (Shizuoka, JP) ; HOSHINO; Wataru;
(Shizuoka, JP) |
Correspondence
Address: |
SUGHRUE-265550
2100 PENNSYLVANIA AVE. NW
WASHINGTON
DC
20037-3213
US
|
Assignee: |
FUJIFILM Corporaion
Tokyo
JP
|
Family ID: |
39875492 |
Appl. No.: |
12/578503 |
Filed: |
October 13, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2008/057187 |
Apr 11, 2008 |
|
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|
12578503 |
|
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Current U.S.
Class: |
430/270.1 ;
430/325; 430/326; 430/331 |
Current CPC
Class: |
G03F 7/325 20130101;
G03F 7/0046 20130101; G03F 7/0397 20130101; G03F 7/2041 20130101;
G03F 7/40 20130101; G03F 7/0045 20130101 |
Class at
Publication: |
430/270.1 ;
430/325; 430/326; 430/331 |
International
Class: |
G03F 7/20 20060101
G03F007/20; G03F 7/004 20060101 G03F007/004 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 13, 2007 |
JP |
P2007-106175 |
Jul 30, 2007 |
JP |
P2007-198054 |
Apr 11, 2008 |
JP |
PCT/JP2008/057187 |
Claims
1. A pattern forming method, comprising: (i) a step of applying a
resist composition whose solubility in a negative tone developer
decreases upon irradiation with an actinic ray or radiation and
which contains a resin having an alicyclic hydrocarbon structure
and a dispersity of 1.7 or less and being capable of increasing a
polarity of the resin by an action of an acid; (ii) an exposure
step; and (iv) a development step using a negative tone
developer.
2. A pattern forming method, comprising: (i) a step of applying a
resist composition whose solubility in a negative tone developer
decreases upon irradiation with an actinic ray or radiation and
which contains a resin having an alicyclic hydrocarbon structure
and a weight average molecular weight of 6,000 or less and being
capable of increasing a polarity of the resin by an action of an
acid; (ii) an exposure step; and (iv) a development step using a
negative tone developer.
3. A pattern forming method, comprising: (i) a step of applying a
resist composition whose solubility in a negative tone developer
decreases upon irradiation with an actinic ray or radiation and
which contains a resin having an alicyclic hydrocarbon structure, a
dispersity of 1.7 or less and a weight average molecular weight of
6,000 or less and being capable of increasing a polarity of the
resin by an action of an acid; (ii) an exposure step; and (iv) a
development step using a negative tone developer.
4. The pattern forming method according to any one of claims 1 to
3, wherein (iv) the development step using a negative tone
developer is a step performed using a developer containing at least
one kind of a solvent selected from organic solvents and having a
vapor pressure of 5.0 kPa or less at 20.degree. C.
5. The pattern forming method according to any one of claims 1 to
3, which further comprises: (vi) a washing step using a rinsing
solution containing an organic solvent.
6. The pattern forming method according to claim 5, wherein the
rinsing solution containing an organic solvent is a rinsing
solution having a vapor pressure of 0.1 kPa or more at 20.degree.
C.
7. The pattern forming method according to any one of claims 1 to
3, which further comprises: (iii) a development step using a
positive tone developer.
8. A resist composition for negative tone development, comprising:
(a1) a resin having an alicyclic hydrocarbon structure and a
dispersity of 1.7 or less and being capable of increasing a
polarity of the resin by an action of an acid; (B) a photo-acid
generator; and (C) a solvent.
9. A resist composition for negative tone development, comprising:
(a2) a resin having an alicyclic hydrocarbon structure and a weight
average molecular weight of 6,000 or less and being capable of
increasing a polarity of the resin by an action of an acid; (B) a
photo-acid generator; and (C) a solvent.
10. A resist composition for negative tone development, comprising:
(a3) a resin having an alicyclic hydrocarbon structure, a
dispersity of 1.7 or less and a weight average molecular weight of
6,000 or less and being capable of increasing a polarity of the
resin by an action of an acid; (B) a photo-acid generator; and (C)
a solvent.
11. A resist composition for multiple development, comprising: (a1)
a resin having an alicyclic hydrocarbon structure and a dispersity
of 1.7 or less and being capable of increasing a polarity of the
resin by an action of an acid; (B) a photo-acid generator; and (C)
a solvent.
12. A resist composition for multiple development, comprising: (a2)
a resin having an alicyclic hydrocarbon structure and a weight
average molecular weight of 6,000 or less and being capable of
increasing a polarity of the resin by an action of an acid; (B) a
photo-acid generator; and (C) a solvent.
13. A resist composition for multiple development, comprising: (a3)
a resin having an alicyclic hydrocarbon structure, a dispersity of
1.7 or less and a weight average molecular weight of 6,000 or less
and being capable of increasing a polarity of the resin by an
action of an acid; (B) a photo-acid generator; and (C) a
solvent.
14. A developer for negative tone development, which is used in the
pattern forming method claimed in any one of claims 1 to 3, the
developer comprising an organic solvent and having a vapor pressure
of 5 kPa or less at 20.degree. C.
15. A rinsing solution for negative tone development, which is used
in the pattern forming method claimed in any one of claims 1 to 3,
the rinsing solution comprising an organic solvent and having a
vapor pressure of 0.1 kPa or more at 20.degree. C.
16. The pattern forming method according to any one of claims 1 to
3, wherein (ii) the exposure step is performed by using an ArF
excimer laser.
17. The pattern forming method according to any one of claims 1 to
3, wherein the negative tone developer is at least one selected
from the group consisting of ketone-based solvent, ester-based
solvent, alcohol-based solvent, amide-based solvent, ether-based
solvent and hydrocarbon-based solvent.
Description
TECHNICAL FIELD
[0001] The present invention relates to a pattern forming method
for use in the process of producing a semiconductor such as IC, in
the production of a circuit board for liquid crystal, thermal head
and the like, and in the lithography process of other
photofabrications; a resist composition for use in the pattern
forming method; a developer for negative tone development used in
the pattern forming method; and a rinsing solution for negative
tone development used in the pattern forming method. More
specifically, the present invention relates to a pattern forming
method suitable for exposure with an ArF exposure apparatus using a
light source that emits far ultraviolet light at a wavelength of
300 nm or less or with an immersion-type projection exposure
apparatus; a resist composition for use in the pattern forming
method; a developer for negative tone development used in the
pattern forming method; and a rinsing solution for negative tone
development used in the pattern forming method.
BACKGROUND ART
[0002] Since the advent of a resist for KrF excimer laser (248 nm),
an image forming method called chemical amplification is used as an
image forming method for a resist so as to compensate for
sensitivity reduction caused by light absorption. For example, the
image forming method by positive tone chemical amplification is an
image forming method of decomposing an acid generator in the
exposed area upon exposure to produce an acid, converting an
alkali-insoluble group into an alkali-soluble group by using the
generated acid as a reaction catalyst in the baking after exposure
(PEB: Post Exposure Bake), and removing the exposed area by alkali
development.
[0003] Along with miniaturization of a semiconductor device, there
is becoming shorter the wavelength of the exposure light source and
higher the numerical aperture (higher NA) of the projection lens,
and an exposure machine using an ArF excimer laser having a
wavelength of 193 nm as a light source has been so far developed.
As commonly well known, these features can be expressed by the
following formulae:
(Resolution)=k.sub.1(.lamda./NA)
(Depth of focus)=.+-.k.sub.2.lamda./NA.sup.2
wherein .lamda. is the wavelength of the exposure light source, NA
is the numerical aperture of the projection lens, and k.sub.1 and
k.sub.2 are coefficients related to the process.
[0004] A so-called immersion method of filling a high
refractive-index liquid (hereinafter sometimes referred to as an
"immersion liquid") between the projection lens and the sample has
been conventionally advocated as a technique for raising the
resolution.
[0005] As for the "effect of immersion", assuming that NA.sub.0=sin
.theta., the above-described resolution and depth of focus in the
immersion can be expressed by the following formulae:
(Resolution)=k.sub.1(.lamda..sub.0/n)/NA.sub.0
(Depth of focus)=.+-.k.sub.2(.lamda..sub.0/n)/NA.sub.0.sup.2
wherein .lamda..sub.0 is the wavelength of exposure light in air, n
is the refractive index of the immersion liquid based on air, and
.theta. is the convergence half-angle of beam.
[0006] That is, the effect of immersion is equal to use of an
exposure wavelength of 1/n. In other words, in the case of a
projection optical system with the same NA, the depth of focus can
be made n times larger by the immersion. This is effective for all
pattern profiles and can be combined with the super-resolution
technology under study at present, such as phase-shift method and
modified illumination method.
[0007] A double exposure technology or a double patterning
technology is being advocated as a technique for more enhancing the
resolution. This is to make small k.sub.1 in the above-described
formula of resolution and is positioned as a resolution-increasing
technology.
[0008] In conventional pattern formation of an electronic device
such as semiconductor device, a mask or reticle pattern in a size
of 4 to 5 times larger than the pattern intended to form is reduced
and transferred on an exposure target such as wafer by using a
reduction projection exposure apparatus.
[0009] However, the dimensional miniaturization brings about a
problem that in the conventional exposure system, lights irradiated
on adjacent patterns interfere with each other to decrease the
optical contrast. Therefore, in such technology, it is devised to
divide the exposure mask design into two or more designs and
synthesize an image by independently exposing these masks. In this
double exposure system where the exposure mask design is divided,
the image of the design must be again synthesized on an exposure
target (wafer) and therefore, the division of the mask design must
be devised so that the pattern on the reticle can be faithfully
reproduced on the exposure target.
[0010] Studies of applying the effect of these double exposure
systems to the transfer of a fine image pattern of a semiconductor
device are introduced, for example, in Patent Document 1
(JP-A-2006-156422 (the term "JP-A" as used herein means an
"unexamined published Japanese patent application")).
[0011] Also, the recent progress of double exposure technology is
reported, for example, in Non-Patent Document 1 (SPIE Proc 5754,
1508 (2005)), Non-Patent Document 2 (SPIE Proc 5377, 1315 (2004)),
and Non-Patent Document 3 (SPIE Proc 61531K-1 (2006)).
[0012] However, in these double exposure systems, the pattern
formation needs to be performed in the vicinity of resolution limit
of the resist and this incurs a problem that sufficient exposure
margin or depth of focus cannot be obtained.
[0013] In other words, if a pattern forming process described, for
example, in Patent Document 2 (JP-A-2001-109154) where a resist
composition containing a resin capable of increasing the polarity
upon exposure is coated on a substrate and the resist film is
exposed and developed to dissolve the exposed area with an alkali
developer, or a pattern forming process described, for example, in
Patent Document 3 (JP-A-2003-76019) where a resist composition
containing a resin capable of increasing the molecular weight upon
exposure is coated on a substrate and the resist film is exposed
and developed to dissolve the unexposed area with an alkali
developer, is applied to a double exposure process, a sufficiently
high resolving performance cannot be obtained.
[0014] With respect to the developer for g-line, i-line, KrF, ArF,
EB or EUV lithography, an aqueous alkali developer of 2.38 mass %
TMAH (tetramethylammonium hydroxide) is being used at present as a
general-purpose developer.
[0015] Other than the above-described developer, for example,
Patent Document 4 (JP-A-2001-215731) describes a developer for
developing a resist material containing a copolymer of a
styrene-based monomer and an acryl-based monomer and dissolving the
exposed portion, where the developer contains an aliphatic linear
ether-based solvent or aromatic ether-based solvent and a
ketone-based solvent having a carbon number of 5 or more; Patent
Document 5 (JP-A-2006-227174) describes a developer for developing
a resist material capable of decreasing the molecular weight as a
result of breakage of the polymer chain upon irradiation with
radiation, thereby dissolving the exposed portion, where the
developer has at least two or more acetic acid groups, ketone
groups, ether groups or phenyl groups and has a molecular weight of
150 or more; and Patent Document 6 (JP-A-6-194847) describes a
developer for developing a resist material mainly composed of a
photosensitive polyhydroxy ether resin obtained by the reaction of
a polyhydroxy ether resin with a diglycidyl (meth)acrylate, where
the developer is an aromatic compound having a carbon number of 6
to 12 or a mixed solvent containing 50 mass % or more of an
aromatic compound having a carbon number of 6 to 12.
[0016] However, these combinations of the resist composition and
the developer mentioned above merely provide a system of forming a
pattern by combining a specific resist composition with a
high-polarity alkali developer or a developer containing a
low-polarity organic solvent.
[0017] That is, as shown in FIG. 1, in the case of a positive tone
system (a combination of a resist composition and a positive tone
developer), a material system of performing the pattern formation
by selectively dissolving and removing a region having strong light
irradiation intensity out of an optical aerial image (light
intensity distribution) is merely provided. On the other hand, as
for the combination of a negative tone system (a resist composition
and a negative tone developer), a material system of performing the
pattern formation by selectively dissolving and removing a region
having a weak light irradiation intensity is merely provided.
[0018] The term "positive tone developer" as used herein indicates
a developer that selectively dissolves and removes the exposed area
not lower than a predetermined threshold value shown by a solid
line in FIG. 1, and the "negative tone developer" indicates a
developer that selectively dissolves and removes the exposed area
not higher than the predetermined threshold value. A development
step using a positive tone developer is called a positive tone
development (sometimes referred to as a positive tone development
step), and a development step using a negative tone developer is
called a negative tone development (sometimes referred to as a
negative tone development step).
[0019] Patent Document 7 (JP-A-2000-199953) describes a double
development technology as the double patterning technology for
improving the resolution. In this case, an image forming method by
chemical amplification in general is utilized, and by making use of
a property that the polarity of a resin in a resist composition
when exposed becomes a high polarity in a region irradiated with a
high light intensity and becomes a low polarity in a region
irradiated with a low light intensity, positive tone development is
performed by dissolving a high exposure region of the resist film
with a high-polarity developer, while negative tone development is
performed by dissolving a low exposure region with a low-polarity
developer. More specifically, the region not lower than an exposure
dose of E2 in FIG. 2 is dissolved using an aqueous alkali solution
as the positive tone developer, the region not higher than an
exposure dose of E1 is dissolved using a specific organic solvent
as the negative tone developer, and, as shown in FIG. 2, the region
with a medium exposure dose (E2 to E1) is allowed to remain without
being developed, whereby an L/S pattern 3 with a pitch half the
pitch of the exposure mask 2 pattern is formed on a wafer 4.
[0020] Patent Document 1: JP-A-2006-156422
[0021] Patent Document 2: JP-A-2001-109154
[0022] Patent Document 3: JP-A-2003-76019
[0023] Patent Document 4: JP-A-2001-215731
[0024] Patent Document 5: JP-A-2006-227174
[0025] Patent Document 6: JP-A-6-194847
[0026] Patent Document 7: JP-A-2000-199953
[0027] Non-Patent Document 1: SPIE Proc 5754, 1508 (2005)
[0028] Non-Patent Document 2: SPIE Proc 5377, 1315 (2004)
[0029] Non-Patent Document 3: SPIE Proc 61531k-1 (2006)
DISCLOSURE OF THE INVENTION
Problems that the Invention is to Solve
[0030] In the conventional double development technology, a
tert-butyl group is employed as an acid-decomposable group in the
resin contained in the resist composition and therefore, the resin
is insufficient to bring out a polarity change large enough to
cause a difference in the dissolution characteristics by a chemical
amplification reaction associated with the exposure.
[0031] Furthermore, since a resin having a styrene skeleton is used
as the resin in the resist composition, the polarity in the low
exposure region of the resist film becomes high and this causes a
problem that the development rate at the development using a
negative tone developer is low and the developability when using a
negative tone developer is bad.
[0032] An object of the present invention is to solve these
problems and provide a pattern forming method for stably forming a
high-precision fine pattern particularly by reducing the line edge
roughness and raising the dimensional uniformity of the pattern so
as to produce a highly integrated electronic device with high
precision.
Means for Solving the Problems
[0033] The present invention has the following constructions, and
the object of the present invention can be attained by these
constructions.
[0034] (1) A pattern forming method, comprising:
[0035] (i) a step of applying a resist composition whose solubility
in a positive tone developer increases and solubility in a negative
tone developer decreases upon irradiation with an actinic ray or
radiation and which contains a resin having an alicyclic
hydrocarbon structure and a dispersity of 1.7 or less and being
capable of increasing a polarity of the resin by an action of an
acid;
[0036] (ii) an exposure step; and
[0037] (iv) a development step using a negative tone developer.
[0038] (2) A pattern forming method, comprising:
[0039] (i) a step of applying a resist composition whose solubility
in a positive tone developer increases and solubility in a negative
tone developer decreases upon irradiation with an actinic ray or
radiation and which contains a resin having an alicyclic
hydrocarbon structure and a weight average molecular weight of
6,000 or less and being capable of increasing a polarity of the
resin by an action of an acid;
[0040] (ii) an exposure step; and
[0041] (iv) a development step using a negative tone developer.
[0042] (3) A pattern forming method, comprising:
[0043] (i) a step of applying a resist composition whose solubility
in a positive tone developer increases and solubility in a negative
tone developer decreases upon irradiation with an actinic ray or
radiation and which contains a resin having an alicyclic
hydrocarbon structure, a dispersity of 1.7 or less and a weight
average molecular weight of 6,000 or less and being capable of
increasing a polarity of the resin by an action of an acid;
[0044] (ii) an exposure step; and
[0045] (iv) a development step using a negative tone developer.
[0046] (4) The pattern forming method according to any one of (1)
to (3) above, wherein
[0047] (iv) the development step using a negative tone developer is
a step performed using a developer containing at least one kind of
a solvent selected from organic solvents and having a vapor
pressure of 5 kPa or less at 20.degree. C.
[0048] (5) The pattern forming method as described in any one of
(1) to (4) above, which further comprises:
[0049] (vi) a washing step using a rinsing solution containing an
organic solvent.
[0050] (6) The pattern forming method as described in (5) above,
wherein the rinsing solution containing an organic solvent is a
rinsing solution having a vapor pressure of 0.1 kPa or more at
20.degree. C.
[0051] (7) The pattern forming method as described in any one of
(1) to (6), which further comprises:
[0052] (iii) a development step using a positive tone
developer.
[0053] (8) A resist composition for negative tone development,
comprising:
[0054] (a1) a resin having an alicyclic hydrocarbon structure and a
dispersity of 1.7 or less and being capable of increasing a
polarity of the resin by an action of an acid;
[0055] (B) a photo-acid generator; and
[0056] (C) a solvent.
[0057] (9) A resist composition for negative tone development,
comprising:
[0058] (a2) a resin having an alicyclic hydrocarbon structure and a
weight average molecular weight of 6,000 or less and being capable
of increasing a polarity of the resin by an action of an acid;
[0059] (B) a photo-acid generator; and
[0060] (C) a solvent.
[0061] (10) A resist composition for negative tone development,
comprising:
[0062] (a3) a resin having an alicyclic hydrocarbon structure, a
dispersity of 1.7 or less and a weight average molecular weight of
6,000 or less and being capable of increasing a polarity of the
resin by an action of an acid;
[0063] (B) a photo-acid generator; and
[0064] (C) a solvent.
[0065] (11) A resist composition for multiple development,
comprising:
[0066] (a1) a resin having an alicyclic hydrocarbon structure and a
dispersity of 1.7 or less and being capable of increasing a
polarity of the resin by an action of an acid;
[0067] (B) a photo-acid generator; and
[0068] (C) a solvent.
[0069] (12) A resist composition for multiple development,
comprising:
[0070] (a2) a resin having an alicyclic hydrocarbon structure and a
weight average molecular weight of 6,000 or less and being capable
of increasing a polarity of the resin by an action of an acid;
[0071] (B) a photo-acid generator; and
[0072] (C) a solvent.
[0073] (13) A resist composition for multiple development,
comprising:
[0074] (a3) a resin having an alicyclic hydrocarbon structure, a
dispersity of 1.7 or less and a weight average molecular weight of
6,000 or less and being capable of increasing a polarity of the
resin by an action of an acid;
[0075] (B) a photo-acid generator; and
[0076] (C) a solvent.
[0077] (14) A developer for negative tone development, which is
used in the pattern forming method described in any one of (1) to
(7) above, the developer comprising an organic solvent and having a
vapor pressure of 5 kPa or less at 20.degree. C.
[0078] (15) A rinsing solution for negative tone development, which
is used in the pattern forming method described in any one of (1)
to (7) above, the rinsing solution comprising an organic solvent
and having a vapor pressure of 0.1 kPa or more at 20.degree. C.
[0079] (16) The pattern forming method as described in any one of
(1) to (7) above, wherein (ii) the exposure step is performed by
using an ArF excimer laser.
[0080] (17) The pattern forming method as described in any one of
(1) to (7) and (16) above,
[0081] wherein the negative tone developer is at least one selected
from the group consisting of ketone-based solvent, ester-based
solvent, alcohol-based solvent, amide-based solvent, ether-based
solvent and hydrocarbon-based solvent.
ADVANTAGE OF THE INVENTION
[0082] According to the present invention, a method of stably
forming a high-precision fine pattern with reduced line edge
roughness and high dimensional uniformity, a resist composition for
negative tone development or multiple development used in the
method, a developer for negative tone development used in the
method, and a rinsing solution for negative tone development used
in the method can be provided.
BRIEF DESCRIPTION OF THE DRAWING
[0083] FIG. 1 is a schematic view showing the relationship among
positive tone development, negative tone development and exposure
dose.
[0084] FIG. 2 is a schematic view showing the pattern forming
method using positive tone development and negative tone
development in combination.
[0085] FIG. 3 is a schematic view showing the relationship among
positive tone development, negative tone development and exposure
dose.
[0086] FIG. 4 is a graph showing the relationship between exposure
dose and residual film curve when a positive tone developer or a
negative tone developer is used.
[0087] FIG. 5 is a schematic view showing the relationship among
positive tone development, negative tone development and exposure
dose.
[0088] FIG. 6 is a schematic view showing the relationship among
positive tone development, negative tone development and exposure
dose in the method of the present invention.
[0089] FIG. 7 is a schematic view showing the relationship among
positive tone development, negative tone development and exposure
dose.
[0090] FIG. 8 is a view showing the spatial intensity distribution
of an optical image.
[0091] FIG. 9 is a schematic view showing the relationship among
positive tone development, threshold value (a) and light
intensity.
[0092] FIG. 10 is a schematic view showing the spatial intensity
distribution of an optical image.
[0093] FIG. 11 is a schematic view showing the relationship among
negative tone development, threshold value (b) and light
intensity.
BEST MODE FOR CARRYING OUT THE INVENTION
[0094] The best mode for carrying out the present invention is
described below.
[0095] Incidentally, in the present invention, when a group (atomic
group) is denoted without specifying whether substituted or
unsubstituted, the group includes both a group having no
substituent and a group having a substituent. For example, an
"alkyl group" includes not only an alkyl group having no
substituent (unsubstituted alkyl group) but also an alkyl group
having a substituent (substituted alkyl group).
[0096] First, the terms used in the context of the present
invention are described. The pattern forming system includes a
positive tone system and a negative tone system and in either
system, a change in the solubility of a resist film in a developer
due to a chemical reaction triggered by light irradiation is
utilized. A system where the light-irradiated part dissolves in a
developer is called a positive tone system, and a system where the
light-unirradiated part dissolves in a developer is called a
negative tone system. The developer used here includes two types of
developers, that is, a positive tone developer and a negative tone
developer. The positive tone developer is a developer that
selectively dissolves and removes the exposed area not lower than a
predetermined threshold value shown in FIG. 1, and the negative
tone developer is a developer that selectively dissolves and
removes an exposed area not higher than the above-described
threshold value. A development step using a positive tone developer
is called a positive tone development (sometimes referred to as a
positive tone development step), and a development step using a
negative tone developer is called a negative tone development
(sometimes referred to as a negative tone development step).
[0097] The present invention provides, as a technique for raising
the resolution, a new pattern forming method by a combination of a
developer (negative tone developer) for selectively dissolving and
removing the exposed area not higher than a predetermined threshold
value (b) as shown in FIG. 3, with a resist composition for
negative tone development, which contains a resin that increases
the polarity by the action of an acid and forms a film whose
solubility in a positive tone developer (preferably an alkali
developer) increases and solubility in a negative tone developer
(preferably an organic developer) decreases upon irradiation with
an actinic ray or radiation.
[0098] The present invention provides, as a technique for raising
the resolution, a new pattern forming method preferably by a
combination of a developer (positive tone developer) for
selectively dissolving and removing the exposed area not lower than
a predetermined threshold value (a) and a developer (negative tone
developer) for selectively dissolving and removing the exposed area
not higher than a predetermined threshold value (b), with a resist
composition for multiple development, which forms a film whose
solubility in a positive tone developer (preferably an alkali
developer) increases and solubility in a negative tone developer
(preferably an organic developer) decreases upon irradiation with
an actinic ray or radiation.
[0099] That is, as shown in FIG. 3, when a pattern element on an
exposure mask is projected on a wafer by light irradiation, the
region having a strong light irradiation intensity (the exposed
area not lower than a predetermined threshold value (a)) is
dissolved and removed using a positive tone developer and the
region having a weak light irradiation intensity (the exposed area
not higher than a predetermined threshold value (b)) is dissolved
and removed using a negative tone developer, whereby a pattern with
resolution as high as 2 times the frequency of the optical spatial
image (light intensity distribution) can be obtained. Also, in the
method of the present invention, the design of the exposure mask
need not be divided.
[0100] As regards the resist composition for multiple development
when performing those two or more development operations at the
same time, a resist composition for negative tone development may
be used as it is.
[0101] The pattern forming process necessary for practicing the
present invention comprises the following steps:
[0102] (i) a step of coating a substrate with a resist composition
whose solubility in a negative tone developer decreases upon
irradiation with an actinic ray or radiation,
[0103] (ii) an exposure step, and
[0104] (iv) a step of developing the resist film with a negative
tone developer.
[0105] The pattern forming method of the present invention
preferably further comprises (vi) a step of washing the resist film
with a rinsing solution for negative tone development.
[0106] The pattern forming method of the present invention
preferably further comprises (iii) a step of developing the resist
film with a positive tone developer.
[0107] The pattern forming method of the present invention
preferably comprises (v) a heating step after the exposure step
(ii).
[0108] In the pattern forming method of the present invention, the
exposure step (ii) may be performed a plurality of times.
[0109] In the pattern forming method of the present invention, the
heating step (v) may be performed a plurality of times.
[0110] In practicing the present invention, (a) a resist
composition whose solubility in a negative tone developer decreases
upon irradiation with an actinic ray or radiation and which
contains a resin having an alicyclic hydrocarbon structure and a
dispersity (molecular weight distribution, Mw/Mn) of 1.7 or less
and/or a weight average molecular weight of 6,000 or less and being
capable of increasing the polarity by the action of an acid, and
(b) a negative tone developer (preferably an organic developer) are
necessary.
[0111] In practicing the present invention, (c) a rinsing solution
for negative tone development is preferably further used.
[0112] In practicing the present invention, (d) a positive tone
developer (preferably an alkali developer) is preferably further
used.
[0113] In the present invention, a pattern forming process using
two kinds of developers, that is, a positive tone developer and a
negative tone developer, is preferred. In this case, the order of
developments is not particularly limited, but it is preferred to
perform development by using a positive tone developer or a
negative tone developer after first exposure and then perform
negative or positive tone development by using a developer
different from that in the first development. After the negative
tone development, the resist film is preferably washed with an
organic solvent-containing rinsing solution for negative tone
development.
[0114] The pattern forming system includes a positive tone system
and a negative tone system and in either system, a change in the
solubility of a resist film in a developer due to a chemical
reaction triggered by light irradiation is utilized. In general, a
system where the light-irradiated part dissolves in a developer is
called a positive tone system, and a system where the
light-unirradiated part dissolves in a developer is called a
negative tone system. The positive tone resist utilizes a chemical
reaction such as polarity conversion for enhancing the solubility
in a developer, and the negative tone resist utilizes bond
formation between molecules, such as crosslinking reaction or
polymerization reaction.
[0115] Since the advent of a resist for KrF excimer laser (248 nm),
an image forming method called chemical amplification is used as an
image forming method for a resist so as to compensate for
sensitivity reduction caused by light absorption. For example, the
image forming method by positive tone chemical amplification is an
image forming method of decomposing an acid generator in the
exposed area upon exposure to generate an acid, converting an
alkali-insoluble group into an alkali-soluble group by using the
generated acid as a reaction catalyst in the baking after exposure
(PEB: Post Exposure Bake), and removing the exposed area by alkali
development.
[0116] In the present invention, one positive tone resist
composition (a) acts as a positive tone resist for a positive tone
developer and at the same time, acts as a negative tone resist for
a negative tone developer.
[0117] In the present invention, an alkali developer (aqueous) can
be used as the positive tone developer, and an organic developer
containing an organic solvent can be used as the negative tone
developer.
[0118] Also, the resist composition (a) is a "resin composition
that forms a film capable of increasing the polarity as a result of
a chemical reaction triggered by exposure to irradiation".
[0119] In conventionally employed negative tone image-forming
systems, a material system utilizing a mechanism of increasing the
molecular weight exclusively by the bonding between molecules and
decreasing the solubility in a developer has been proposed.
However, it has been difficult for the image forming mechanism
utilizing a change in the molecular weight to establish a system of
allowing one resist material system to act as a positive tone
resist for one developer and act as a negative tone resist for
another developer.
[0120] In the present invention, the resist composition (a) not
only causes a decrease of the solubility in a negative tone
developer due to a polarity conversion reaction of the polymer side
chain but also brings about both an increase of the solubility in
an alkali developer and a decrease of the solubility in an organic
developer particularly by virtue of a specific chemical reaction
(the polarity conversion reaction of the polymer side chain) at the
same time.
[0121] In the present invention, the matter of importance is to
control the "threshold value" of exposure dose (the exposure dose
for solubilizing or insolubilizing the film by a developer in the
light-irradiated region). The "threshold value" is the minimum
exposure dose for solubilizing the film by a positive tone
developer and the maximum exposure dose for insolubilizing the film
by a negative tone developer so as to obtain a desired line width
at the time of performing pattern formation.
[0122] The "threshold value" can be determined as follows.
[0123] That is, the "threshold value" is the maximum exposure dose
for solubilizing the film by a positive tone developer and the
minimum exposure dose for insolubilizing the film by a negative
tone developer so as to obtain a desired line width at the time of
performing pattern formation.
[0124] More strictly, the threshold value is defined as
follows.
[0125] The residual film ratio of the resist film to the exposure
dose is measured and at this time, as shown in FIG. 4, the minimum
exposure dose giving a residual film ratio of 0% for the positive
tone developer is designated as a threshold value (a) and the
minimum exposure dose giving a residual film ratio of 100% for the
negative tone developer is designated as a threshold value (b).
[0126] For example, as shown in FIG. 5, the threshold value (a) of
the exposure dose for solubilizing the film by a positive tone
developer is set to be higher than the threshold value (b) for
solubilizing the film by a negative tone developer, whereby pattern
formation can be achieved by one exposure operation. That is, as
shown in FIG. 6, after a resist is coated on a wafer and exposed,
the portion not lower than the threshold value (a) of the exposure
dose is dissolved with a positive tone developer and then, the
region not higher than the threshold value (b) of the exposure dose
is dissolved with a negative tone developer, whereby pattern
formation can be performed by one exposure operation. In this case,
as for the order of the development with a positive tone developer
and the development with a negative tone developer, either
development may be performed earlier. After the negative tone
development, when the resist film is washed with a rinsing solution
containing an organic solvent, more successful pattern formation
can be achieved.
[0127] The method for controlling the threshold value includes a
method of controlling the material-related parameters of the resist
composition (a) and the developer or controlling the parameters
related to the process.
[0128] As for the material-related parameter, control of various
physical values related to solubility of the resist composition (a)
in the developer and the organic solvent, such as SP value
(solubility parameter) and LogP value, is effective. Specific
examples of the parameter include, for the polymer contained in the
resist composition (a), the average molecular weight, the molecular
weight dispersity, the monomer compositional ratio, the polarity of
monomer, the monomer sequence, the polymer blend and the addition
of low molecular additive, and for the developer, include the
concentration of developer, the addition of low molecular additive
and the addition of surfactant.
[0129] Also, specific examples of the process-related parameter
include the film formation temperature, the film formation time,
the temperature and time of post-heating after exposure, the
temperature at development, the development time, the nozzle system
(puddle method) of developing apparatus, and the rinsing method
after development.
[0130] Accordingly, for obtaining a good pattern in the pattern
forming method using negative tone development as well as in the
pattern forming method by multiple development using negative tone
development and positive tone development in combination, it is
important to combine the above-described material-related
parameters and process parameters while appropriately controlling
these parameters.
[0131] The pattern forming process using two kinds of developers,
namely, a positive tone developer and a negative tone developer,
may be a process where the exposure is performed once as described
above or where the exposure is performed two or more times by the
following process. That is, development using a positive tone
developer or a negative tone developer is performed after first
exposure, and negative or positive tone development using a
developer different from that in the first development is performed
after second exposure.
[0132] A pattern forming method comprising, in order:
[0133] (i) a step of coating a substrate with a resist composition
for multiple development, whose solubility in a positive tone
developer increases and solubility in a negative tone developer
decreases upon irradiation with an actinic ray or radiation,
[0134] (ii-1) a first exposure step,
[0135] (v-1) a first heating step,
[0136] (iii) a step of developing the resist film with a positive
tone developer,
[0137] (ii-2) a second exposure step,
[0138] (v-2) a second heating step, and
[0139] (iv) a step of developing the resist film with a negative
tone developer.
[0140] A pattern forming method comprising, in order:
[0141] (i) a step of coating a substrate with a resist composition
for multiple development, whose solubility in a positive tone
developer increases and solubility in a negative tone developer
decreases upon irradiation with an actinic ray or radiation,
[0142] (ii-1) a first exposure step,
[0143] (v-1) a first heating step,
[0144] (iv) a step of developing the resist film with a negative
tone developer,
[0145] (ii-2) a second exposure step,
[0146] (v-2) a second heating step, and
[0147] (iii) a step of developing the resist film with a positive
tone developer.
[0148] As regards the resist composition for multiple development,
the resist composition described later can be used.
[0149] When exposure is performed two or more times, this is
advantageous in that the latitude of control of the threshold value
in the development after first exposure and control of the
threshold value in the development after second exposure
increases.
[0150] In the case of performing the exposure two or more times,
the second exposure dose is preferably set to be larger than the
first exposure dose. Because, as shown in FIG. 7, in the second
development, the threshold value is determined based on the amount
to which the history of first and second exposure doses are added,
and when the second exposure dose is sufficiently larger than the
first exposure dose, the effect of the first exposure dose is
reduced and depending on the case, can be neglected.
[0151] The exposure dose (Eo1 [mJ/cm.sup.2]) in the step of
performing the first exposure is preferably 5 [mJ/cm.sup.2] or more
smaller than the exposure dose (Eo2 [mJ/cm.sup.2]) in the step of
performing the second exposure. In this case, the history of the
first exposure can be made to less affect the process of performing
pattern formation by the second exposure.
[0152] In the case of performing the exposure two times, the first
development is not limited to positive tone development, and
development using a negative tone developer may be performed
first.
[0153] For changing the first exposure dose and the second exposure
dose, a method of adjusting the above-described various parameters
related to the material and process is effective. In particular,
control of the temperature in the first heating step and the
temperature in the second heating step is effective. That is, in
order to make the first exposure dose to be smaller than the second
exposure dose, it is effective to set the temperature in the first
heating step to be lower than the temperature in the second heating
step.
[0154] The threshold value (a) in the positive tone development is
determined as follows in the actual lithography process.
[0155] A film composed of a resist composition whose solubility in
a positive tone developer increases and solubility in a negative
tone developer decreases upon irradiation with an actinic ray or
radiation is formed on a substrate, and the resist film is exposed
through a photomask having a desired pattern size under desired
illumination conditions. At this time, the exposure is performed by
varying the exposure focus in 0.05 [.mu.m] steps and the exposure
dose in 0.5 [mJ/cm.sup.2] steps.
[0156] After the exposure, the resist film is heated at a desired
temperature for a desired time and then developed with an alkali
developer in a desired concentration for a desired time. After the
development, the line width of the pattern is measured using
CD-SEM, and the exposure dose A [mJ/cm.sup.2] and focus position
for forming a desired line width are determined. Subsequently, the
intensity distribution of an optical image when the above-described
photomask is irradiated with a specific exposure dose A
[mJ/cm.sup.2] and a specific focus position is calculated. The
calculation can be performed using a simulation software (Prolith,
ver. 9.2.0.15, produced by KLA). Details of the calculation method
are described in Chris. A. Mack, Inside PROLITH, Chapter 2, "Aerial
Image Formation", FINLE Technologies, Inc.
[0157] As a result of calculation, for example, the spatial
intensity distribution shown in FIG. 8 of an optical image is
obtained.
[0158] Here, as shown in FIG. 9, the light intensity at a position
after the spatial position is shifted by 1/2 of the obtained
pattern line width from the minimum value in the spatial intensity
distribution of an optical image becomes the threshold value
(a).
[0159] The threshold value (b) in the negative tone development is
determined as follows in the actual lithography process.
[0160] A film composed of a resist composition whose solubility in
a positive tone developer increases and solubility in a negative
tone developer decreases upon irradiation with an actinic ray or
radiation is formed on a substrate, and the resist film is exposed
through a photomask having a desired pattern size under desired
illumination conditions. At this time, the exposure is performed by
varying the exposure focus in 0.05 [.mu.m] steps and the exposure
dose in 0.5 [mJ/cm.sup.2] steps.
[0161] After the exposure, the resist film is heated at a desired
temperature for a desired time and then developed with an organic
developer in a desired concentration for a desired time. After the
development, the line width of the pattern is measured using
CD-SEM, and the exposure dose A [mJ/cm.sup.2] and focus position
for forming a desired line width are determined. Subsequently, the
intensity distribution of an optical image when the above-described
photomask is irradiated with a specific exposure dose A
[mJ/cm.sup.2] and a specific focus position is calculated. The
calculation is performed using a simulation software (Prolith,
produced by KLA).
[0162] For example, a spatial intensity distribution shown in FIG.
10 of an optical image is obtained.
[0163] Here, as shown in FIG. 11, the light intensity at a position
after the spatial position is shifted by 1/2 of the obtained
pattern line width from the maximum value in the spatial intensity
distribution of an optical image is defined as the threshold value
(b).
[0164] The threshold value (a) is preferably from 0.1 to 100
[mJ/cm.sup.2], more preferably from 0.5 to 50 [mJ/cm.sup.2], still
more preferably from 1 to 30 [mJ/cm.sup.2]. The threshold value (b)
is preferably from 0.1 to 100 [mJ/cm.sup.2], more preferably from
0.5 to 50 [mJ/cm.sup.2], still more preferably from 1 to 30
[mJ/cm.sup.2].
[0165] The difference between threshold values (a) and (b) is
preferably from 0.1 to 80 [mJ/cm.sup.2], more preferably from 0.5
to 50 [mJ/cm.sup.2], still more preferably from 1 to 30
[mJ/cm.sup.2].
[0166] At the time of performing positive tone development, an
alkali developer is preferably used.
[0167] The alkali developer which can be used in performing
positive tone development is, for example, an alkaline aqueous
solution of inorganic alkalis such as sodium hydroxide, potassium
hydroxide, sodium carbonate, sodium silicate, sodium metasilicate
and aqueous ammonia, primary amines such as ethylamine and
n-propylamine, secondary amines such as diethylamine and
di-n-butylamine, tertiary amines such as triethylamine and
methyldiethyl-amine, alcohol amines such as dimethylethanolamine
and triethanolamine, quaternary ammonium salts such as
tetramethylammonium hydroxide and tetraethylammonium hydroxide, and
cyclic amines such as pyrrole and piperidine.
[0168] Furthermore, this alkaline aqueous solution may be used
after adding thereto alcohols and a surfactant each in an
appropriate amount.
[0169] The alkali concentration of the alkali developer is usually
from 0.1 to 20 mass %.
[0170] The pH of the alkali developer is usually from 10.0 to
15.0.
[0171] In particular, an aqueous 2.38% tetramethylammonium
hydroxide solution is preferred.
[0172] As for the rinsing solution in the rinsing treatment
performed after positive tone development, pure water is used, and
the pure water may be used after adding thereto a surfactant in an
appropriate amount.
[0173] At the time of performing negative tone development, an
organic developer containing an organic solvent is preferably
used.
[0174] As for the organic developer which can be used in performing
negative tone development, a polar solvent such as ketone-based
solvent, ester-based solvent, alcohol-based solvent, amide-based
solvent and ether-based solvent, and a hydrocarbon-based solvent
can be used. For example, there may be used a ketone-based solvent
such as 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone,
4-heptanone, 2-hexanone, diisobutyl ketone, cyclohexanone,
methylcyclohexanone, phenylacetone, methyl ethyl ketone and methyl
isobutyl ketone; and an ester-based solvent such as methyl acetate,
butyl acetate, ethyl acetate, isopropyl acetate, amyl acetate,
propylene glycol monomethyl ether acetate, ethylene glycol
monoethyl ether acetate, diethylene glycol monobutyl ether acetate,
diethylene glycol monoethyl ether acetate,
ethyl-3-ethoxypropionate, 3-methoxybutyl acetate,
3-methyl-3-methoxybutyl acetate, methyl formate, ethyl formate,
butyl formate, propyl formate, ethyl lactate, butyl lactate and
propyl lactate.
[0175] Examples of the alcohol-based solvent include an alcohol
such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl
alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol,
isobutyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl
alcohol and n-decanol; a glycol-based solvent such as ethylene
glycol, diethylene glycol and triethylene glycol; and a glycol
ether-based solvent such as ethylene glycol monomethyl ether,
propylene glycol monomethyl ether, ethylene glycol monoethyl ether,
propylene glycol monoethyl ether, diethylene glycol monomethyl
ether, triethylene glycol monoethyl ether and methoxymethyl
butanol.
[0176] Examples of the ether-based solvent include, in addition to
the glycol ether-based solvents above, dioxane and
tetrahydrofuran.
[0177] Examples of the amide-based solvent which can be used
include N-methyl-2-pyrrolidone, N,N-dimethylacetamide and
N,N-dimethylformamide.
[0178] Examples of the hydrocarbon-based solvent include an
aromatic hydrocarbon-based solvent such as toluene and xylene, and
an aliphatic hydrocarbon-based solvent such as pentane, hexane,
octane and decane.
[0179] A plurality of these solvents may be mixed, or the solvent
may be used by mixing it with a solvent other than those described
above or water.
[0180] As regards the development system, for example, a method of
raising the developer on a substrate surface by the effect of a
surface tension and keeping it still for a fixed time, thereby
performing the development (puddle method), a method of spraying
the developer on a substrate surface (spray method), and a method
of continuously ejecting the developer on a substrate rotating at a
constant speed while scanning the developer ejecting nozzle at a
constant rate (dynamic dispense method) may be applied. In using
such a development method, if the vapor pressure of the negative
tone developer is high, the substrate surface is cooled due to
evaporation of the developer to reduce the temperature of the
developer and the film of the resist composition formed on the
substrate is not dissolved at a constant rate, giving rise to
deterioration of the dimensional uniformity. For this reason, the
vapor pressure at 20.degree. C. of the developer which can be used
in performing negative tone development is preferably 5 kPa or
less, more preferably 3 kPa or less, and most preferably 2 kPa or
less.
[0181] Specific examples of the developer having a vapor pressure
of 5 kPa or less at 20.degree. C. include a ketone-based solvent
such as 1-octanone, 2-octanone, 1-nonanone, 2-nonanone,
4-heptanone, 2-hexanone, diisobutyl ketone, cyclohexanone,
methylcyclohexanone, phenylacetone and methyl isobutyl ketone; an
ester-based solvent such as butyl acetate, amyl acetate, propylene
glycol monomethyl ether acetate, ethylene glycol monoethyl ether
acetate, diethylene glycol monobutyl ether acetate, diethylene
glycol monoethyl ether acetate, ethyl-3-ethoxypropionate,
3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, butyl
formate, propyl formate, ethyl lactate, butyl lactate and propyl
lactate; an alcohol-based solvent such as n-propyl alcohol,
isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl
alcohol, isobutyl alcohol, n-hexyl alcohol, n-heptyl alcohol,
n-octyl alcohol and n-decanol; a glycol-based solvent such as
ethylene glycol, diethylene glycol and triethylene glycol; a glycol
ether-based solvent such as propylene glycol monomethyl ether,
ethylene glycol monoethyl ether, propylene glycol monoethyl ether,
diethylene glycol monomethyl ether, triethylene glycol monoethyl
ether and methoxymethylbutanol; an ether-based solvent such as
tetrahydrofuran; an amide-based solvent such as
N-methyl-2-pyrrolidone, N,N-dimethylacetamide and
N,N-dimethylformamide; an aromatic hydrocarbon-based solvent such
as toluene and xylene; and an aliphatic hydrocarbon-based solvent
such as octane and decane.
[0182] Specific examples of the developer having a vapor pressure
of 2 kPa or less at 20.degree. C., which is a most preferred range,
include a ketone-based solvent such as 1-octanone, 2-octanone,
1-nonanone, 2-nonanone, 4-heptanone, 2-hexanone, diisobutyl ketone,
cyclohexanone, methylcyclohexanone and phenylacetone; an
ester-based solvent such as butyl acetate, amyl acetate, propylene
glycol monomethyl ether acetate, ethylene glycol monoethyl ether
acetate, diethylene glycol monobutyl ether acetate, diethylene
glycol monoethyl ether acetate, ethyl-3-ethoxypropionate,
3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, ethyl
lactate, butyl lactate and propyl lactate; an alcohol-based solvent
such as n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol,
isobutyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl
alcohol and n-decanol; a glycol-based solvent such as ethylene
glycol, diethylene glycol and triethylene glycol; a glycol
ether-based solvent such as propylene glycol monomethyl ether,
ethylene glycol monoethyl ether, propylene glycol monoethyl ether,
diethylene glycol monomethyl ether, triethylene glycol monoethyl
ether and methoxymethylbutanol; an amide-based solvent such as
N-methyl-2-pyrrolidone, N,N-dimethylacetamide and
N,N-dimethylformamide; an aromatic hydrocarbon-based solvent such
as xylene; and an aliphatic hydrocarbon-based solvent such as
octane and decane.
[0183] In the developer usable when performing negative tone
development, a surfactant can be added in an appropriate amount, if
desired.
[0184] The surfactant is not particularly limited but, for example,
an ionic or nonionic fluorine-containing and/or silicon-containing
surfactant can be used. Examples of such a fluorine-containing
and/or silicon-containing surfactant include the surfactants
described in JP-A-62-36663, JP-A-61-226746, JP-A-61-226745,
JP-A-62-170950, JP-A-63-34540, JP-A-7-230165, JP-A-8-62834,
JP-A-9-54432, JP-A-9-5988 and U.S. Pat. Nos. 5,405,720, 5,360,692,
5,529,881, 5,296,330, 5,436,098, 5,576,143, 5,294,511 and
5,824,451. The surfactant is preferably a nonionic surfactant. The
nonionic surfactant is not particularly limited, but a
fluorine-containing surfactant or a silicon-containing surfactant
is more preferred.
[0185] The amount of the surfactant used is usually from 0.001 to 5
mass %, preferably from 0.005 to 2 mass %, more preferably from
0.01 to 0.5 mass %, based on the entire amount of the
developer.
[0186] After the step of performing negative tone development, a
step of stopping the development by the replacement with another
solvent may be practiced.
[0187] A step of washing the resist film with a rinsing solution
containing an organic solvent is preferably provided after the
negative tone development.
[0188] A method where after washing with a rinsing solution, the
rinsing solution is removed from the substrate surface by rotating
the substrate at a rotation number of 2,000 rpm to 4,000 rpm, is
preferred. In the case where the vapor pressure of the rinsing
solution is low, the rinsing solution remains on the substrate even
after removing the rinsing solution by rotating the substrate and
penetrates into the resist pattern formed on the substrate to swell
the resist pattern, as a result, the dimensional uniformity of the
resist pattern is deteriorated. For this reason, the vapor pressure
at 20.degree. C. of the rinsing solution is preferably 0.05 kPa or
more, more preferably 0.1 kPa or more, and most preferably 0.12 kPa
or more.
[0189] In the rinsing step after negative tone development, the
washing is preferably performed using a rinsing solution containing
at least one kind of an organic solvent selected from an
alkane-based solvent, a ketone-based solvent, an ester-based
solvent, an alcohol-based solvent, an amide-based solvent and an
ether-based solvent. Preferably, a step of washing the resist film
by using a rinsing solution containing at least one kind of an
organic solvent selected from a ketone-based solvent, an
ester-based solvent, an alcohol-based solvent and an amide-based
solvent is preformed after negative tone development; more
preferably, a step of washing the resist film by using a rinsing
solution containing an alcohol-based solvent or an ester-based
solvent is performed after negative tone development; still more
preferably, a step of washing the resist film by using a rinsing
solution containing a monohydric alcohol having a carbon number of
6 to 8 is performed after negative tone development. The monohydric
alcohol having a carbon number of 6 to 8, which is used in the
rinsing step after negative tone development, includes a linear,
branched or cyclic monohydric alcohol, and specific examples of the
monohydric alcohol which can be used include 1-hexanol, 1-heptanol,
1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol,
3-octanol, 4-octanol and benzyl alcohol, with 1-hexanol, 2-hexanol
and 2-heptanol being preferred.
[0190] A plurality of these components may be mixed, or the solvent
may be used by mixing it with an organic solvent other than those
described above.
[0191] The water content in the rinsing solution is preferably 10
mass % or less, more preferably 5 mass % or less, still more
preferably 3 mass % or less. By setting the water content to 10
mass % or less, good development characteristics can be
obtained.
[0192] The rinsing solution may also be used after adding thereto a
surfactant in an appropriate amount.
[0193] In the rinsing step, the wafer after negative tone
development is washed using the above-described organic
solvent-containing rinsing solution. The method of washing
treatment is not particularly limited but, for example, a method of
continuously ejecting the rinsing solution on a substrate rotating
at a constant speed (spin coating method), a method of dipping the
substrate in a bath filled with the rinsing solution for a fixed
time (dipping method), and a method of spraying the rinsing
solution on the substrate surface (spraying method) may be applied.
Above all, a method where the washing treatment is performed by the
spin coating method and after the washing, the rinsing solution is
removed from the substrate surface by rotating the substrate at a
rotation number of 2,000 rpm to 4,000 rpm, is preferred.
[0194] As regards the development method, for example, a method of
dipping the substrate in a bath filled with the developer for a
fixed time (dipping method), a method of raising the developer on
the substrate surface by the effect of a surface tension and
keeping it still for a fixed time, thereby performing the
development (puddle method), a method of spraying the developer on
a substrate surface (spraying method), and a method of continuously
ejecting the developer on the substrate rotating at a constant
speed while scanning the developer ejecting nozzle at a constant
rate (dynamic dispense method) may be applied.
[0195] In the pattern forming method of the present invention, the
step of forming a film on a substrate by using a resist composition
whose solubility in a positive tone developer increases and
solubility in a negative tone developer decreases upon irradiation
with an actinic ray or radiation, the step of exposing the film,
the step of heating the film, and the step of applying positive
tone development to the film may be performed by generally known
methods.
[0196] The exposure apparatus for use in the present invention is
not limited in the light source wavelength, but, for example, a KrF
excimer laser wavelength (248 nm), an ArF excimer laser wavelength
(193 nm) and an F.sub.2 excimer laser wavelength (157 .mu.m) can be
applied.
[0197] In the step of performing exposure of the present invention,
an immersion exposure method can be applied.
[0198] The immersion exposure method is a technique for raising the
resolution, and this is a technique of performing the exposure by
filling a high refractive-index liquid (hereinafter sometimes
referred to as an "immersion liquid") between the projection lens
and the sample.
[0199] As for the "effect of immersion", assuming that NA.sub.0=sin
.theta., the resolution and depth of focus when immersed can be
expressed by the following formulae:
(Resolution)=k.sub.1(.lamda..sub.0/n)/NA.sub.0
(Depth of focus)=k.sub.2(.lamda..sub.0/n)/NA.sub.0.sup.2
wherein .lamda..sub.0 is the wavelength of exposure light in air, n
is the refractive index of the immersion liquid based on air, and
.theta. is the convergence half-angle of beam.
[0200] That is, the effect of immersion is equal to use of an
exposure wavelength of 1/n. In other words, when the projection
optical system has the same NA, the depth of focus can be made n
times larger by the immersion. This is effective for all pattern
profiles and can be combined with the super-resolution technology
under study at present, such as phase-shift method and modified
illumination method.
[0201] In the case of performing immersion exposure, a step of
washing the film surface with an aqueous chemical solution may be
performed (1) before the exposure step after forming the film on a
substrate and/or (2) after the step of exposing the film through an
immersion liquid but before the step of heating the film.
[0202] The immersion liquid is preferably a liquid being
transparent to light at the exposure wavelength and having as small
a temperature coefficient of refractive index as possible so as to
minimize the distortion of an optical image projected on the film.
Particularly, when the exposure light source is an ArF excimer
laser (wavelength: 193 nm), water is preferably used in view of
easy availability and easy handleability, in addition to the
above-described aspects.
[0203] In the case of using water, an additive (liquid) capable of
decreasing the surface tension of water and increasing the surface
activity may be added in a small ratio. This additive is preferably
a liquid that does not dissolve the resist layer on the wafer and
at the same time, gives only a negligible effect on the optical
coat at the undersurface of the lens element.
[0204] Such an additive is preferably, for example, an aliphatic
alcohol having a refractive index nearly equal to that of water,
and specific examples thereof include methyl alcohol, ethyl alcohol
and isopropyl alcohol. By virtue of adding an alcohol having a
refractive index nearly equal to that of water, even when the
alcohol component in water is evaporated and its content
concentration is changed, the change in the refractive index of the
entire liquid can be advantageously made very small.
[0205] On the other hand, if a substance opaque to light at 193 nm
or an impurity greatly differing in the refractive index from water
is mingled, this incurs distortion of the optical image projected
on the resist. Therefore, the water used is preferably distilled
water. Pure water after further filtration through an ion exchange
filter or the like may also be used.
[0206] In the present invention, the substrate on which the film is
formed is not particularly limited, and an inorganic substrate such
as silicon, SiN, SiO.sub.2 and SiN, a coating-type inorganic
substrate such as SOG, or a substrate generally used in the process
of producing a semiconductor such as IC or producing a circuit
board of liquid crystal, thermal head or the like or in the
lithography process of other photofabrications can be used. If
desired, an organic antireflection film may be formed between the
film and the substrate.
[0207] In the present invention, the film formed on the substrate
is a film composed of a resist composition whose solubility in a
positive tone developer increases and solubility in a negative tone
developer decreases upon irradiation with an actinic ray or
radiation.
[0208] The resist composition which can be used in the present
invention is described below. (A) Resin capable of increasing the
polarity by the action of an acid
[0209] The resin capable of increasing the polarity by the action
of an acid, which is used in the resist composition of the present
invention, is a resin having a group that decomposes by the action
of an acid to produce an alkali-soluble group (hereinafter
sometimes referred to as an "acid-decomposable group"), on either
one or both of the main chain and the side chain of the resin
(sometimes referred to as an "acid-decomposable resin", an
"acid-decomposable resin (A)" or a "resin (A)). The resin is
preferably a resin whose solubility in a positive tone developer
increases and which has a monocyclic or polycyclic alicyclic
hydrocarbon structure and can increase the porality, increase the
solubility in an alkali developer and decrease the solubility in an
organic solvent by the action of an acid (hereinafter sometimes
referred to as an "alicyclic hydrocarbon-based acid-decomposable
resin"). Because, the polarity of the resin is greatly changed
between before and after irradiation of an actinic ray or radiation
and when the resist film is developed using a positive tone
developer (preferably an alkali developer) and a negative tone
developer (preferably an organic solvent), the dissolution contrast
rises. Furthermore, the resin having a monocyclic or polycyclic
alicyclic hydrocarbon structure generally has high hydrophobicity
and ensures a high development rate at the time of developing the
resist film in the region of weak light irradiation intensity with
a negative tone developer (preferably an organic developer), and
the developability in using a negative tone developer is
enhanced.
[0210] The group capable of decomposing by the action of an acid
(acid-decomposable groups) is preferably a group obtained by
substituting the hydrogen atom of an alkali-soluble group with a
group capable of leaving by the action of an acid.
[0211] Examples of the alkali-soluble group include groups having a
phenolic hydroxyl group, a carboxylic acid group, a fluorinated
alcohol group, a sulfonic acid group, a sulfonamide group, a
sulfonylimide group, an (alkylsulfonyl)(alkylcarbonyl)methylene
group, an (alkylsulfonyl)(alkylcarbonyl)imide group, a
bis(alkylcarbonyl)methylene group, a bis(alkylcarbonyl)imide group,
a bis(alkylsulfonyl)methylene group, a bis(alkylsulfonyl)imide
group, a tris(alkylcarbonyl)methylene group or a
tris(alkylsulfonyl)methylene group.
[0212] The alkali-soluble group is preferably a carboxylic acid
group, a fluorinated alcohol group (preferably
hexafluoroisopropanol) or a sulfonic acid group.
[0213] Examples of the group capable of leaving by the action of an
acid include --C(R.sub.36)(R.sub.37)(R.sub.38),
--C(R.sub.36)(R.sub.37)(OR.sub.39) and
--C(R.sub.01)(R.sub.02)(OR.sub.39).
[0214] In the formulae, each of R.sub.36 to R.sub.39 independently
represents an alkyl group, a cycloalkyl group, an aryl group, an
aralkyl group or an alkenyl group. R.sub.36 and R.sub.37 may
combine with each other to form a ring.
[0215] Each of R.sub.01 and R.sub.02 independently represents a
hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group,
an aralkyl group or an alkenyl group.
[0216] The acid-decomposable group is preferably a cumyl ester
group, an enol ester group, an acetal ester group, a tertiary alkyl
ester group or the like, more preferably a tertiary alkyl ester
group.
[0217] The resist composition of the present invention containing a
resin (A) having a monocyclic or polycyclic alicyclic hydrocarbon
structure and being capable of increasing the polarity by the
action of an acid can be suitably used when ArF excimer laser light
is irradiated.
[0218] The resin having a monocyclic or polycyclic alicyclic
hydrocarbon structure and being capable of increasing the polarity
by the action of an acid (hereinafter sometimes referred to as an
"alicyclic hydrocarbon-based acid-decomposable resin") is
preferably a resin containing at least one member selected from the
group consisting of a repeating unit having an alicyclic
hydrocarbon-containing partial structure represented by any one of
the following formulae (pI) to (pV) and a repeating unit
represented by the following formula (II-AB).
##STR00001##
[0219] In formulae (pI) to (pV), R.sub.11 represents a methyl
group, an ethyl group, an n-propyl group, an isopropyl group, an
n-butyl group, an isobutyl group or a sec-butyl group.
[0220] Z represents an atomic group necessary for forming a
cycloalkyl group together with the carbon atom.
[0221] Each of R.sub.12 to R.sub.16 independently represents a
linear or branched alkyl group having a carbon number of 1 to 4 or
a cycloalkyl group, provided that at least one of R.sub.12 to
R.sub.14 or either one of R.sub.15 and R.sub.16 represents a
cycloalkyl group.
[0222] Each of R.sub.17 to R.sub.21 independently represents a
hydrogen atom, a linear or branched alkyl group having a carbon
number of 1 to 4 or a cycloalkyl group, provided that at least one
of R.sub.17 to R.sub.21 represents a cycloalkyl group and that
either one of R.sub.19 and R.sub.21 represents a linear or branched
alkyl group having a carbon number of 1 to 4 or a cycloalkyl
group.
[0223] Each of R.sub.22 to R.sub.25 independently represents a
hydrogen atom, a linear or branched alkyl group having a carbon
number of 1 to 4 or a cycloalkyl group, provided that at least one
of R.sub.22 to R.sub.25 represents a cycloalkyl group. R.sub.23 and
R.sub.24 may combine with each other to form a ring.
##STR00002##
[0224] In formula (II-AB), each of R.sub.11' and R.sub.12'
independently represents a hydrogen atom, a cyano group, a halogen
atom or an alkyl group.
[0225] Z' represents an atomic group for forming an alicyclic
structure containing two bonded carbon atoms (C--C).
[0226] Formula (II-AB) is preferably the following formula (II-AB1)
or (II-AB2):
##STR00003##
[0227] In formulae (II-AB1) and (II-AB2), each of R.sub.13' to
R.sub.16' independently represents a hydrogen atom, a halogen atom,
a cyano group, --COOH, --COOR.sub.5, a group capable of decomposing
by the action of an acid, --C(.dbd.O)--X-A'--R.sub.17', an alkyl
group or a cycloalkyl group, and at least two members out of
R.sub.13' to R.sub.16' may combine to form a ring.
[0228] R.sub.5 represents an alkyl group, a cycloalkyl group or a
group having a lactone structure.
[0229] X represents an oxygen atom, a sulfur atom, --NH--,
--NHSO.sub.2-- or --NHSO.sub.2NH--.
[0230] A' represents a single bond or a divalent linking group.
[0231] R.sub.17' represents --COOH, --COOR.sub.5, --CN, a hydroxyl
group, an alkoxy group, --CO--NH--R.sub.6,
--CO--NH--SO.sub.2--R.sub.6 or a group having a lactone
structure.
[0232] R.sub.6 represents an alkyl group or a cycloalkyl group.
[0233] n represents 0 or 1.
[0234] In formulae (pI) to (pV), the alkyl group of R.sub.12 to
R.sub.25 is a linear or branched alkyl group having a carbon number
of 1 to 4.
[0235] The cycloalkyl group of R.sub.11 to R.sub.25 and the
cycloalkyl group formed by Z together with the carbon atom may be
monocyclic or polycyclic. Specific examples thereof include a group
having a carbon number of 5 or more and having a monocyclo,
bicyclo, tricyclo or tetracyclo structure or the like. The carbon
number thereof is preferably from 6 to 30, more preferably from 7
to 25. These cycloalkyl groups each may have a substituent.
[0236] Preferred examples of the cycloalkyl group include an
adamantyl group, a noradamantyl group, a decalin residue, a
tricyclodecanyl group, a tetracyclododecanyl group, a norbornyl
group, a cedrol group, a cyclopentyl group, a cyclohexyl group, a
cycloheptyl group, a cyclooctyl group, a cyclodecanyl group and a
cyclododecanyl group. Among these, more preferred are an adamantyl
group, a norbornyl group, a cyclohexyl group, a cyclopentyl group,
a tetracyclododecanyl group and a tricyclodecanyl group.
[0237] Examples of the substituent which the alkyl group and
cycloalkyl group each may further have include an alkyl group
(having a carbon number of 1 to 4), a halogen atom, a hydroxyl
group, an alkoxy group (having a carbon number of 1 to 4), a
carboxyl group and an alkoxycarbonyl group (having a carbon number
of 2 to 6). Examples of the substituent which these alkyl group,
alkoxy group, alkoxycarbonyl group and the like each may further
have include a hydroxyl group, a halogen atom and an alkoxy
group.
[0238] The structures represented by formulae (pI) to (pV) each can
be used for the protection of an alkali-soluble group in the resin.
Examples of the alkali-soluble group include various groups known
in this technical field.
[0239] Specific examples thereof include a structure where the
hydrogen atom of a carboxylic acid group, a sulfonic acid group, a
phenol group or a thiol group is replaced by the structure
represented by any one of formulae (pI) to (pV). Among these,
preferred is a structure where the hydrogen atom of a carboxylic
acid group or a sulfonic acid group is replaced by the structure
represented by any one of formulae (pI) to (pV).
[0240] The repeating unit having an alkali-soluble group protected
by the structure represented by any one of formulae (pI) to (pV) is
preferably a repeating unit represented by the following formula
(pA):
##STR00004##
[0241] In the formula, R represents a hydrogen atom, a halogen atom
or a linear or branched alkyl group having a carbon number of 1 to
4, and a plurality of R's may be the same or different from each
other.
[0242] A represents a single bond, or a sole group or a combination
of two or more groups selected from the group consisting of an
alkylene group, an ether group, a thioether group, a carbonyl
group, an ester group, an amido group, a sulfonamido group, a
urethane group and a ureylene group, and is preferably a single
bond.
[0243] R.sub.p1 represents a group represented by any one of
formulae (pI) to (pV).
[0244] The repeating unit represented by formula (pA) is more
preferably a repeating unit composed of a 2-alkyl-2-adamantyl
(meth)acrylate or a dialkyl(1-adamantyl)methyl (meth)acrylate.
[0245] Specific examples of the repeating unit having an
acid-decomposable group are set forth below, but the present
invention is not limited thereto.
[0246] (In the formulae, Rx represents H, CH.sub.3 or CH.sub.2OH,
and each of Rxa and Rxb independently represents an alkyl group
having a carbon number of 1 to 4.)
##STR00005## ##STR00006## ##STR00007## ##STR00008##
[0247] Examples of the halogen atom of R.sub.11' and R.sub.12' in
formula (II-AB) include a chlorine atom, a bromine atom, a fluorine
atom and an iodine atom.
[0248] The alkyl group of R.sub.11' and R.sub.12' includes a linear
or branched alkyl group having a carbon number of 1 to 10.
[0249] The atomic group of Z' for forming an alicyclic structure is
an atomic group for forming, in the resin, a repeating unit
composed of an alicyclic hydrocarbon which may have a substituent.
Above all, an atomic group for forming a crosslinked alicyclic
structure to form a crosslinked alicyclic hydrocarbon repeating
unit is preferred.
[0250] Examples of the skeleton of the alicyclic hydrocarbon formed
are the same as those of the alicyclic hydrocarbon group of
R.sub.12 to R.sub.25 in formulae (pI) to (pV).
[0251] The skeleton of the alicyclic hydrocarbon may have a
substituent, and examples of the substituent include R.sub.13' to
R.sub.16' in formulae (II-AB1) and (II-AB2).
[0252] In the alicyclic hydrocarbon-based acid-decomposable resin
for use in the present invention, the group capable of decomposing
by the action of an acid may be contained in at least one repeating
unit out of the repeating unit having an alicyclic
hydrocarbon-containing partial structure represented by any one of
formulae (pI) to (pV), the repeating unit represented by formula
(II-AB), and the repeating unit composed of a copolymerization
component described later. The group capable of decomposing by the
action of an acid is preferably contained in the repeating unit
having an alicylcic hydrocarbon-containing partial structure
represented by any one of formulae (pI) to (pV).
[0253] Various substituents R.sub.13' to R.sub.16' in formulae
(II-AB1) and (II-AB2) may become substituents of the atomic group
Z' for forming an alicyclic structure or the atomic group Z' for
forming a crosslinked alicyclic structure in formula (II-AB).
[0254] Specific examples of the repeating units represented by
formulae (II-AB1) and (II-AB2) are set forth below, but the present
invention is not limited to these specific examples.
##STR00009## ##STR00010## ##STR00011## ##STR00012##
##STR00013##
[0255] The alicyclic hydrocarbon-based acid-decomposable resin for
use in the present invention preferably has a lactone group. As for
the lactone group, any group may be used as long as it has a
lactone structure, but a group having a 5- to 7-membered ring
lactone structure is preferred. The 5- to 7-membered ring lactone
structure is preferably condensed with another ring structure in
the form of forming a bicyclo or spiro structure. The resin more
preferably has a repeating unit containing a group having a lactone
structure represented by any one of the following formulae (LC1-1)
to (LC1-16). The group having a lactone structure may be bonded
directly to the main chain. Among these lactone structures,
preferred are groups represented by formulae (LC1-1), (LC1-4),
(LC1-5), (LC1-6), (LC1-13) and (LC1-14). By virtue of using a
specific lactone structure, the line edge roughness and development
defect are improved.
##STR00014## ##STR00015##
[0256] The lactone structure moiety may or may not have a
substituent (Rb.sub.2). Preferred examples of the substituent
(Rb.sub.2) include an alkyl group having a carbon number of 1 to 8,
a cycloalkyl group having a carbon number of 4 to 7, an alkoxy
group having a carbon number of 1 to 8, an alkoxycarbonyl group
having a carbon number of 2 to 8, a carboxyl group, a halogen atom,
a hydroxyl group, a cyano group and an acid-decomposable group.
n.sub.2 represents an integer of 0 to 4. When n.sub.2 is an integer
of 2 or more, each Rb.sub.2 may be the same as or different from
every other Rb.sub.2 and also, the plurality of substituents
(Rb.sub.2) may combine with each other to form a ring.
[0257] Examples of the repeating unit containing a group having a
lactone structure represented by any one of formulae (LC1-1) to
(LC1-16) include a repeating unit where at least one of R.sub.13'
to R.sub.16' in formula (II-AB1) or (II-AB2) has a group
represented by any one of formulae (LC1-1) to (LC1-16) (for
example, R.sub.5 of --COOR.sub.5 is a group represented by any one
of formulae (LC1-1) to (LC1-16)), and a repeating unit represented
by the following formula (A1):
##STR00016##
[0258] In formula (AI), Rb.sub.0 represents a hydrogen atom, a
halogen atom or an alkyl group having a carbon number of 1 to
4.
[0259] Preferred examples of the substituent which the alkyl group
of Rb.sub.0 may have include a hydroxyl group and a halogen
atom.
[0260] The halogen atom of Rb.sub.0 includes a fluorine atom, a
chlorine atom, a bromine atom and an iodine atom.
[0261] Rb.sub.0 is preferably a hydrogen atom, a methyl group, a
hydroxymethyl group or a trifluoromethyl group, particularly
preferably a hydrogen atom or a methyl group.
[0262] Ab represents a single bond, an alkylene group, a divalent
linking group having a monocyclic or polycyclic alicyclic
hydrocarbon structure, an ether group, an ester group, a carbonyl
group, or a divalent group formed by combining these groups and is
preferably a single bond or a linking group represented by
-Ab.sub.1-CO.sub.2--. Ab.sub.1 represents a linear or branched
alkylene group or a monocyclic or polycyclic cycloalkylene group
and is preferably a methylene group, an ethylene group, a
cyclohexylene group, an adamantylene group or a norbornylene
group.
[0263] V represents a group represented by any one of formulae
(LC1-1) to (LC1-16).
[0264] The repeating unit having a lactone structure usually has an
optical isomer, but any optical isomer may be used. One optical
isomer may be used alone or a mixture of a plurality of optical
isomers may be used. In the case of mainly using one optical
isomer, the optical purity (ee) thereof is preferably 90 or more,
more preferably 95 or more.
[0265] Specific examples of the repeating unit having a lactone
structure are set forth below, but the present invention is not
limited thereto.
[0266] (In the formulae, Rx is H, CH.sub.3, CH.sub.2OH or
CF.sub.3.)
##STR00017## ##STR00018##
(In the formulae, Rx is H, CH.sub.3, CH.sub.2OH or CF.sub.3.)
##STR00019## ##STR00020## ##STR00021## ##STR00022##
[0267] (In the formulae, Rx is H, CH.sub.3, CH.sub.2OH or
CF.sub.3.)
##STR00023## ##STR00024##
[0268] The alicyclic hydrocarbon-based acid-decomposable resin for
use in the present invention preferably has a repeating unit
containing an organic group having a polar group, more preferably a
repeating unit having an alicyclic hydrocarbon structure
substituted by a polar group. By virtue of this repeating unit, the
adherence to substrate and the affinity for developer are enhanced.
The alicyclic hydrocarbon structure of the polar group-substituted
alicyclic hydrocarbon structure is preferably an adamantyl group, a
diamantyl group or a norbornane group. The polar group is
preferably a hydroxyl group or a cyano group.
[0269] The polar group-substituted alicyclic hydrocarbon structure
is preferably a partial structure represented by the following
formulae (VIIa) to (VIId):
##STR00025##
[0270] In formulae (VIIa) to (VIIc), each of R.sub.2c to R.sub.4c
independently represents a hydrogen atom, a hydroxyl group or a
cyano group, provided that at least one of R.sub.2c to R.sub.4c
represents a hydroxyl group or a cyano group. A structure where one
or two members out of R.sub.2c to R.sub.4c are a hydroxyl group
with the remaining being a hydrogen atom is preferred.
[0271] In formula (VIIa), it is more preferred that two members out
of R.sub.2c to R.sub.4c, are a hydroxyl group and the remaining is
a hydrogen atom.
[0272] The repeating unit having a group represented by any one of
formulae (VIIa) to (VIId) includes a repeating unit where at least
one of R.sub.13' to R.sub.16' in formula (II-AB1) or (II-AB2) has a
group represented by any one of formulae (VIIa) to (VIId) (for
example, R.sub.5 of --COOR.sub.5 is a group represented by any one
of formulae (VIIa) to (VIId)), and repeating units represented by
the following formulae (AIIa) to (AIId):
##STR00026##
[0273] In formulae (AIIa) to (AIId), R.sub.1c represents a hydrogen
atom, a methyl group, a trifluoromethyl group or a hydroxymethyl
group.
[0274] R.sub.2c to R.sub.4c have the same meanings as R.sub.2c to
R.sub.4c in formulae (VIIa) to (VIIc).
[0275] Specific examples of the repeating unit having a structure
represented by any one of formulae (AIIa) to (AIId) are set forth
below, but the present invention is not limited thereto.
##STR00027## ##STR00028##
[0276] The alicyclic hydrocarbon-based acid-decomposable resin for
use in the present invention may contain a repeating unit
represented by the following formula (VIII):
##STR00029##
[0277] In formula (VIII), Z.sub.2 represents --O-- or
--N(R.sub.41)--. R.sub.41 represents a hydrogen atom, a hydroxyl
group, an alkyl group or --OSO.sub.2--R.sub.42. R.sub.42 represents
an alkyl group, a cycloalkyl group or a camphor residue. The alkyl
group of R.sub.41 and R.sub.42 may be substituted by a halogen atom
(preferably fluorine atom) or the like.
[0278] Specific examples of the repeating unit represented by
formula (VIII) are set forth below, but the present invention is
not limited thereto.
##STR00030##
[0279] The alicyclic hydrocarbon-based acid-decomposable resin for
use in the present invention preferably contains a repeating unit
having an alkali-soluble group, more preferably a repeating unit
having a carboxyl group. By virtue of containing this repeating
unit, the resolution increases in the usage of forming contact
holes. As for the repeating unit having a carboxyl group, a
repeating unit where a carboxyl group is directly bonded to the
resin main chain, such as repeating unit by an acrylic acid or a
methacrylic acid, a repeating unit where a carboxyl group is bonded
to the resin main chain through a linking group, and a repeating
unit where a carboxyl group is introduced into the terminal of the
polymer chain by using a polymerization initiator or chain transfer
agent having an alkali-soluble group at the polymerization, all are
preferred. The linking group may have a monocyclic or polycyclic
hydrocarbon structure. A repeating unit by an acrylic acid or a
methacrylic acid is more preferred.
[0280] The alicyclic hydrocarbon-based acid-decomposable resin for
use in the present invention may further contain a repeating unit
having from 1 to 3 groups represented by formula (F1). Thanks to
this repeating unit, the performance in terms of line edge
roughness is enhanced.
##STR00031##
[0281] In formula (F1), each of R.sub.50 to R.sub.55 independently
represents a hydrogen atom, a fluorine atom or an alkyl group,
provided that at least one of R.sub.50 to R.sub.55 is a fluorine
atom or an alkyl group with at least one hydrogen atom being
substituted by a fluorine atom.
[0282] Rx represents a hydrogen atom or an organic group
(preferably an acid-decomposable protective group, an alkyl group,
a cycloalkyl group, an acyl group or an alkoxycarbonyl group).
[0283] The alkyl group of R.sub.50 to R.sub.55 may be substituted
by a halogen atom (e.g., fluorine), a cyano group or the like, and
the alkyl group is preferably an alkyl group having a carbon number
of 1 to 3, such as methyl group and trifluoromethyl group.
[0284] It is preferred that R.sub.50 to R.sub.55 all are a fluorine
atom.
[0285] The organic group represented by Rx is preferably an
acid-decomposable protective group, an alkyl group, a cycloalkyl
group, an acyl group, an alkylcarbonyl group, an alkoxycarbonyl
group, an alkoxycarbonylmethyl group, an alkoxymethyl group or a
1-alkoxyethyl group, each of which may have a substituent.
[0286] The repeating unit having a group represented by formula
(F1) is preferably a repeating unit represented by the following
formula (F2):
##STR00032##
[0287] In formula (F2), Rx represents a hydrogen atom, a halogen
atom or an alkyl group having a carbon number of 1 to 4. Preferred
examples of the substituent which the alkyl group of Rx may have
include a hydroxyl group and a halogen atom.
[0288] Fa represents a single bond or a linear or branched alkylene
group and is preferably a single bond.
[0289] Fb represents a monocyclic or polycyclic hydrocarbon
group.
[0290] Fc represents a single bond or a linear or branched alkylene
group and is preferably a single bond or a methylene group.
[0291] F.sub.1 represents a group represented by formula (F1).
[0292] p.sub.1 represents a number of 1 to 3.
[0293] The cyclic hydrocarbon group in Fb is preferably a
cyclopentyl group, a cyclohexyl group or a norbornyl group.
[0294] Specific examples of the repeating unit having a group
represented by formula (F1) are set forth below, but the present
invention is not limited thereto.
##STR00033##
[0295] The alicyclic hydrocarbon-based acid-decomposable resin for
use in the present invention may further contain a repeating unit
having an alicyclic hydrocarbon structure and not exhibiting acid
decomposability. Thanks to this repeating unit, the dissolving out
of low molecular components from the resist film to the immersion
liquid at the immersion exposure can be reduced. Examples of this
repeating unit include 1-adamantyl (meth)acrylate, tricyclodecanyl
(meth)acrylate and cyclohexyl (meth)acrylate.
[0296] As a repeating unit having an alicyclic hydrocarbon
structure and not exhibiting acid decomposability, for example, a
repeating unit having neither a hydroxyl group nor a cyano group is
exemplified, and a repeating unit represented by formula (IX) is
preferred:
##STR00034##
[0297] In formula (IX), R.sub.5 represents a hydrocarbon group
having at least one cyclic structure and having neither a hydroxyl
group nor a cyano group.
[0298] Ra represents a hydrogen atom, an alkyl group or a
--CH.sub.2--O-Ra.sub.2 group, wherein Ra.sub.2 represents a
hydrogen atom, an alkyl group or an acyl group. Ra is preferably a
hydrogen atom, a methyl group, a hydroxymethyl group or a
trifluoromethyl group, particularly preferably a hydrogen atom or a
methyl group.
[0299] The cyclic structure possessed by R.sub.5 includes a
monocyclic hydrocarbon group and a polycyclic hydrocarbon group.
Examples of the monocyclic hydrocarbon group include a cycloalkyl
group having a carbon number of 3 to 12, such as cyclopentyl group,
cyclohexyl group, cycloheptyl group and cyclooctyl group, and a
cycloalkenyl group having a carbon number of 3 to 12, such as
cyclohexenyl group. As the monocyclic hydrocarbon group, a
monocyclic hydrocarbon group having a carbon number of 3 to 7 is
preferred, and a cyclopentyl group and a cyclohexyl group are more
preferred.
[0300] The polycyclic hydrocarbon group includes a ring gathered
hydrocarbon group and a crosslinked cyclic hydrocarbon group.
Examples of the ring gathered hydrocarbon group include a
bicyclohexyl group and a perhydronaphthalenyl group. Examples of
the crosslinked cyclic hydrocarbon ring include a bicyclic
hydrocarbon ring such as pinane, bomane, norpinane, norbornane and
bicyclooctane rings (e.g., bicyclo[2.2.2]octane ring,
bicyclo[3.2.1]octane ring), a tricyclic hydrocarbon ring such as
homobredane, adamantane, tricyclo[5.2.1.0.sup.2,6]decane and
tricyclo[4.3.1.1.sup.2,5]undecane rings, and a tetracyclic
hydrocarbon ring such as
tetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]dodecane and
perhydro-1,4-methano-5,8-methanonaphthalene rings. The crosslinked
cyclic hydrocarbon ring also includes a condensed cyclic
hydrocarbon ring, and examples thereof include a condensed ring
formed by condensing a plurality of 5- to 8-membered cycloalkane
rings such as perhydronaphthalene (decalin), perhydroanthracene,
perhydrophenanthrene, perhydroacenaphthene, perhydrofluorene,
perhydroindene and perhydrophenanthrene rings.
[0301] As the crosslinked cyclic hydrocarbon ring, a norbornyl
group, an adamantyl group, a bicyclooctanyl group, a
tricyclo[5.2.1.0.sup.2,6]decanyl group are preferred, and a
norbornyl group and an adamantyl group are more preferred.
[0302] Such an alicyclic hydrocarbon group may have a substituent,
and preferred examples of the substituent include a halogen atom,
an alkyl group, a hydroxyl group protected by a protective group,
and an amino group protected by a protective group. Preferred
halogen atoms include bromine, chlorine and fluorine atoms, and
preferred alkyl groups include methyl, ethyl, butyl and tert-butyl
groups. This alkyl group may further have a substituent, and the
substituent which the alkyl group may further have includes a
halogen atom, an alkyl group, a hydroxyl group protected by a
protective group, and an amino group protected by a protective
group.
[0303] Examples of the protective group include an alkyl group, a
cycloalkyl group, an aralkyl group, a substituted methyl group, a
substituted ethyl group, an acyl group, an alkoxycarbonyl group and
an aralkyloxycarbonyl group. For example, the alkyl group is
preferably an alkyl group having a carbon number of 1 to 4, the
substituted methyl group is preferably a methoxymethyl,
methoxythiomethyl, benzyloxymethyl, tert-butoxymethyl or
2-methoxyethoxymethyl group, the substituted ethyl group is
preferably a 1-ethoxyethyl or 1-methyl-1-methoxyethyl group, the
acyl group is preferably an aliphatic acyl group having a carbon
number of 1 to 6, such as formyl, acetyl, propionyl, butyryl,
isobutyryl, valeryl and pivaloyl groups, and the alkoxycarbonyl
group is preferably an alkoxycarbonyl group having a carbon number
of 1 to 4.
[0304] The content of the repeating unit represented by formula
(IX) having neither a hydroxyl group nor a cyano group is
preferably from 0 to 40 mol %, more preferably from 0 to 20 mol %,
based on all repeating units in the alicyclic hydrocarbon-based
acid-decomposable resin.
[0305] Specific examples of the repeating unit represented by
formula (IX) are set forth below, but the present invention is not
limited thereto.
[0306] In formulae, Ra represents H, CH.sub.3, CH.sub.2OH or
CF.sub.3.
##STR00035## ##STR00036##
[0307] The alicyclic hydrocarbon-based acid-decomposable resin for
use in the present invention may contain, in addition to the
above-described repeating units, various repeating structural units
for the purpose of controlling dry etching resistance, suitability
for standard developer, adherence to substrate, resist profile and
properties generally required of the resist, such as resolution,
heat resistance and sensitivity.
[0308] Examples of such a repeating structural unit include, but
are not limited to, repeating structural units corresponding to the
monomers described below.
[0309] Thanks to such a repeating structural unit, the performance
required of the alicyclic hydrocarbon-based acid-decomposable
resin, particularly, (1) solubility in coating solvent, (2)
film-forming property (glass transition point), (3) solubility in
positive or negative tone developer, (4) film loss (selection of
hydrophilic, hydrophobic and alkali-soluble group), (5) adherence
of unexposed area to substrate, (6) dry etching resistance, and the
like, can be subtly controlled.
[0310] Examples of the monomer include a compound having one
addition-polymerizable unsaturated bond selected from acrylic acid
esters, methacrylic acid esters, acrylamides, methacrylamides,
allyl compounds, vinyl ethers and vinyl esters.
[0311] Other than these, an addition-polymerizable unsaturated
compound copolymerizable with the monomers corresponding to the
above-described various repeating structural units may be
copolymerized.
[0312] In the alicyclic hydrocarbon-based acid-decomposable resin,
the molar ratio of respective repeating structural units contained
is appropriately determined to control the dry etching resistance
of resist, suitability for standard developer, adherence to
substrate, resist profile and performances generally required of
the resist, such as resolution, heat resistance and
sensitivity.
[0313] The preferred embodiment of the alicyclic hydrocarbon-based
acid-decomposable resin for use in the present invention includes
the followings:
[0314] (1) a resin containing a repeating unit having an alicyclic
hydrocarbon-containing partial structure represented by any one of
formulae (pI) to (pV) (side chain type), preferably a resin
containing a (meth)acrylate repeating unit having a structure
represented by any one of formulae (pI) to (pV), and
[0315] (2) a resin containing a repeating unit represented by
formula (II-AB) (main chain type).
[0316] The resin of (2) further includes:
[0317] (3) a resin having a repeating unit represented by formula
(II-AB), a maleic anhydride derivative and a (meth)acrylate
structure (hybrid type).
[0318] In the alicyclic hydrocarbon-based acid-decomposable resin,
the content of the repeating unit having an acid-decomposable group
is preferably from 10 to 60 mol %, more preferably from 20 to 50
mol %, still more preferably from 30 to 50 mol %, based on all
repeating structural units.
[0319] In the alicyclic hydrocarbon-based acid-decomposable resin,
the content of the repeating unit having an alicyclic
hydrocarbon-containing partial structure represented by any one of
formulae (pI) to (pV) is preferably from 20 to 70 mol %, more
preferably from 20 to 50 mol %, still more preferably from 30 to 50
mol %, based on all repeating structural units.
[0320] In the alicyclic hydrocarbon-based acid-decomposable resin,
the content of the repeating unit represented by formula (II-AB) is
preferably from 10 to 60 mol %, more preferably from 15 to 55 mol
%, still more preferably from 20 to 50 mol %, based on all
repeating structural units.
[0321] In the acid-decomposable resin, the content of the repeating
unit having a lactone ring is preferably from 10 to 70 mol %, more
preferably from 20 to 60 mol %, still more preferably from 25 to 50
mol %, based on all repeating structural units.
[0322] In the acid-decomposable resin, the content of the repeating
unit having a polar group-containing organic group is preferably
from 1 to 40 mol %, more preferably from 5 to 30 mol %, still more
preferably from 5 to 20 mol %, based on all repeating structural
units.
[0323] The content of the repeating structural unit based on the
monomer as the further copolymerization component in the resin can
also be appropriately selected according to the desired resist
performance but in general, the content thereof is preferably 99
mol % or less, more preferably 90 mol % or less, still more
preferably 80 mol % or less, based on the total molar number of the
repeating structural unit having an alicyclic
hydrocarbon-containing partial structure represented by any one of
formulae (pI) to (pV) and the repeating unit represented by formula
(II-AB).
[0324] In the case of using the resist composition of the present
invention for ArF exposure, the acid-decomposable resin (A)
preferably has no aromatic group in view of transparency to ArF
light.
[0325] The alicyclic hydrocarbon-based acid-decomposable resin for
use in the present invention is preferably a resin where all
repeating units are composed of a (meth)acrylate-based repeating
unit. In this case, the repeating units may be all a
methacrylate-based repeating unit, all an acrylate-based repeating
unit, or all a mixture of methacrylate-based repeating
unit/acrylate-based repeating unit, but the acrylate-based
repeating unit preferably accounts for 50 mol % or less of all
repeating units.
[0326] The alicyclic hydrocarbon-based acid-decomposable resin is
preferably a copolymer having at least three kinds of repeating
units, that is, a (meth)acrylate-based repeating unit having a
lactone ring, a (meth)acrylate-based repeating unit having an
organic group substituted by at least either a hydroxyl group or a
cyano group, and a (meth)acrylate-based repeating unit having an
acid-decomposable group.
[0327] The copolymer is preferably a ternary copolymerization
polymer containing from 20 to 50 mol % of the repeating unit having
an alicyclic hydrocarbon-containing partial structure represented
by any one of formulae (pI) to (pV), from 20 to 50 mol % of the
repeating unit having a lactone structure and from 5 to 30 mol % of
the repeating unit having a polar group-substituted alicyclic
hydrocarbon structure, or a quaternary copolymerization polymer
further containing from 0 to 20 mol % of other repeating units.
[0328] In particular, the resin is preferably a ternary
copolymerization polymer containing from 20 to 50 mol % of an
acid-decomposable group-containing repeating unit represented by
any one of the following formulae (ARA-1) to (ARA-5), from 20 to 50
mol % of a lactone group-containing repeating unit represented by
any one of the following formulae (ARL-1) to (ARL-6), and from 5 to
30 mol % of a repeating unit having a polar group-substituted
alicyclic hydrocarbon structure represented by any one of the
following formulae (ARH-1) to (ARH-3), or a quaternary
copolymerization polymer further containing from 5 to 20 mol % of a
repeating unit having a carboxyl group or a structure represented
by formula (F1) and a repeating unit having an alicyclic
hydrocarbon structure and not exhibiting acid decomposability.
[0329] (In the formulae, Rxy.sub.1 represents a hydrogen atom or a
methyl group, and Rxa.sub.1 and Rxb.sub.1 each represents a methyl
group or an ethyl group).
##STR00037## ##STR00038## ##STR00039##
[0330] The alicyclic hydrocarbon-based acid-decomposable resin for
use in the present invention can be synthesized by an ordinary
method (for example, radical polymerization). Examples of the
synthesis method in general include a batch polymerization method
of dissolving the monomer species and an initiator in a solvent and
heating the solution, thereby effecting the polymerization, and a
dropping polymerization method of adding dropwise a solution
containing monomer species and an initiator to a heated solvent
over 1 to 10 hours. A dropping polymerization method is preferred.
Examples of the reaction solvent include tetrahydrofuran,
1,4-dioxane, ethers such as diisopropyl ether, ketones such as
methyl ethyl ketone and methyl isobutyl ketone, an ester solvent
such as ethyl acetate, an amide solvent such as dimethylformamide
and dimethylacetamide, and the later-described solvent capable of
dissolving the composition of the present invention, such as
propylene glycol monomethyl ether acetate, propylene glycol
monomethyl ether and cyclohexanone. The polymerization is more
preferably performed using the same solvent as the solvent used in
the resist composition of the present invention. By the use of this
solvent, production of particles during storage can be
suppressed.
[0331] The polymerization reaction is preferably performed in an
inert gas atmosphere such as nitrogen and argon. As for the
polymerization initiator, the polymerization is started using a
commercially available radical initiator (e.g., azo-based
initiator, peroxide). The radical initiator is preferably an
azo-based initiator, and an azo-based initiator having an ester
group, a cyano group or a carboxyl group is preferred. Preferred
examples of the initiator include azobisisobutyronitrile,
azobisdimethylvaleronitrile and dimethyl
2,2'-azobis(2-methylpropionate). The initiator is added
additionally or in parts, if desired. After the completion of
reaction, the reaction product is charged into a solvent, and the
desired polymer is recovered by a method such as powder or solid
recovery. The reaction concentration is from 5 to 50 mass %,
preferably from 10 to 30 mass %.
[0332] The reaction temperature is usually from 10 to 150.degree.
C., preferably from 30 to 120.degree. C., more preferably from 60
to 100.degree. C.
[0333] The purification may be performed by the same method as that
for the resin (D) described later, and a normal method, for
example, a liquid-liquid extraction method of combining water
washing with an appropriate solvent to remove residual monomers or
oligomer components, a purification method in a solution sate, such
as ultrafiltration of extracting and removing only polymers having
a molecular weight lower than a specific molecular weight, a
reprecipitation method of adding dropwise the resin solution in a
poor solvent to solidify the resin in the poor solvent and thereby
remove residual monomers and the like, or a purification method in
a solid state, such as washing of the resin slurry with a poor
solvent after separation by filtration, may be employed.
[0334] The weight average molecular weight of the resin for use in
the present invention is preferably 6,000 or less, more preferably
from 1,000 to 5,000, still more preferably from 2,000 to 3,500, in
terms of polystyrene by the GPC method. When the weight average
molecular weight of the resin is 6,000 or less, the line edge
roughness of the resist pattern is reduced.
[0335] The dispersity (molecular weight distribution, Mw/Mn) is
preferably 1.7 or less, more preferably 1.5 or less, still more
preferably 1.3 or less. As the dispersity is smaller, the line edge
roughness of the resist pattern is more reduced.
[0336] To speak in more detail, the resin for use in the present
invention is (a1) a resin having an alicyclic hydrocarbon structure
and a dispersity of 1.7 or less and being capable of increasing the
polarity by the action of an acid, or (a2) a resin having an
alicyclic hydrocarbon structure and a weight average molecular
weight of 6,000 or less and being capable of increasing the
polarity by the action of an acid, preferably (a3) a resin having
an alicyclic hydrocarbon structure, a dispersity of 1.7 or less and
a weight average molecular weight of 6,000 or less and being
capable of increasing the polarity by the action of an acid.
[0337] The molecular weight can be controlled by adjusting the
amount added of the radical initiator, and as the amount added of
the initiator material is larger, the molecular weight becomes
smaller. As for the control of dispersity, a living polymerization
method or the like disclosed in JP-A-2004-220009 may be used, and
in addition, the dispersity can also be reduced by raising the
proportion of the good solvent for the resin during precipitation
when synthesizing the resin.
[0338] In the resin for use in the present invention, by combining
the weight average molecular weight and the dispersity in
respective preferred ranges, the line edge roughness can be more
reduced.
[0339] In the resist composition of the present invention, the
amount of all resins for use in the present invention blended in
the entire composition is preferably from 50 to 99.9 mass %, more
preferably from 60 to 99.0 mass %, based on the entire solid
content.
[0340] In the present invention, one kind of a resin may be used or
a plurality of kinds of resins may be used in combination.
[0341] The alicyclic hydrocarbon-based acid-decomposable resin for
use in the present invention preferably contains no fluorine or
silicon atom in view of compatibility with the resin (D).
(B) Compound Capable of Generating an Acid Upon Irradiation with an
Actinic Ray or Radiation
[0342] The resist composition of the present invention contains a
compound capable of generating an acid upon irradiation with an
actinic ray or radiation (sometimes referred to as a "photo-acid
generator" or "component (B)").
[0343] The photo-acid generator which can be used may be
appropriately selected from a photo-initiator for cationic
photopolymerization, a photo-initiator for radical
photopolymerization, a photodecoloring agent for dyes, a
photodiscoloring agent, a known compound used for microresist or
the like and capable of generating an acid upon irradiation with an
actinic ray or radiation, and a mixture thereof.
[0344] Examples thereof include a diazonium salt, a phosphonium
salt, a sulfonium salt, an iodonium salt, an imidosulfonate, an
oxime sulfonate, a diazodisulfone, a disulfone and an o-nitrobenzyl
sulfonate.
[0345] Also, a compound where such a group or compound capable of
generating an acid upon irradiation with an actinic ray or
radiation is introduced into the main or side chain of the polymer,
for example, compounds described in U.S. Pat. No. 3,849,137, German
Patent 3,914,407, JP-A-63-26653, JP-A-55-164824, JP-A-62-69263,
JP-A-63-146038, JP-A-63-163452, JP-A-62-153853 and JP-A-63-146029,
may be used.
[0346] Furthermore, compounds capable of generating an acid by the
effect of light described, for example, in U.S. Pat. No. 3,779,778
and European Patent 126,712 may also be used.
[0347] Out of the compounds capable of generating an acid upon
irradiation with an actinic ray or radiation, preferred are the
compounds represented by the following formulae (ZI), (ZII) and
(ZIII):
##STR00040##
[0348] In formula (ZI), each of R.sub.201, R.sub.202 and R.sub.203
independently represents an organic group.
[0349] X.sup.- represents a non-nucleophilic anion, and preferred
examples thereof include sulfonate anion, carboxylate anion,
bis(alkylsulfonyl)amide anion, tris(alkylsulfonyl)methide anion,
BF.sub.4.sup.-, PF.sub.6.sup.- and SbF.sub.6.sup.-. The anion is
preferably an organic anion containing a carbon atom.
[0350] The preferred organic anion includes organic anions
represented by the following formulae:
##STR00041##
[0351] In the formulae, Rc.sub.1 represents an organic group.
[0352] The organic group of Rc.sub.1 includes an organic group
having a carbon number of 1 to 30, and preferred examples thereof
include an alkyl group which may be substituted, an aryl group
which may be substituted, and a group where a plurality of these
groups are connected through a single bond or a linking group such
as --O--, --CO.sub.2--, --S--, --SO.sub.3-- and
--SO.sub.2N(Rd.sub.1)--. R.sub.d1 represents a hydrogen atom or an
alkyl group.
[0353] Each of Rc.sub.3, Rc.sub.4 and Rc.sub.5 independently
represents an organic group. Preferred organic groups of Rc.sub.3,
Rc.sub.4 and Rc.sub.5 are the same as preferred organic groups in
Rc.sub.1. The organic group is most preferably a perfluoroalkyl
group having a carbon number of 1 to 4.
[0354] Rc.sub.3 and Rc.sub.4 may combine to form a ring. The group
formed by combining Rc.sub.3 and Rc.sub.4 includes an alkylene
group and an arylene group, and a perfluoroalkylene group having a
carbon number of 2 to 4 is preferred.
[0355] The organic group of Rc.sub.1 and Rc.sub.3 to Rc.sub.5 is
particularly preferably an alkyl group with the 1-position being
substituted by a fluorine atom or a fluoroalkyl group, or a phenyl
group substituted by a fluorine atom or a fluoroalkyl group. By
virtue of having a fluorine atom or a fluoroalkyl group, the
acidity of the acid generated upon irradiation with light is raised
and the sensitivity is enhanced. Also, when Rc.sub.3 and Rc.sub.4
are combined to form a ring, the acidity of the acid generated upon
irradiation with light is raised and the sensitivity is
enhanced.
[0356] The carbon number of the organic group as R.sub.201,
R.sub.202 and R.sub.203 is generally from 1 to 30, preferably from
1 to 20.
[0357] Two members out of R.sub.201 to R.sub.203 may combine to
form a ring structure, and the ring may contain an oxygen atom, a
sulfur atom, an ester bond, an amide bond or a carbonyl group.
Examples of the group formed by combining two members out of
R.sub.201 to R.sub.203 include an alkylene group (e.g., butylene,
pentylene).
[0358] Specific examples of the organic group as R.sub.201,
R.sub.202 and R.sub.203 include corresponding groups in the
compounds (ZI-1), (ZI-2) and (ZI-3) which are described later.
[0359] The compound may be a compound having a plurality of
structures represented by formula (ZI). For example, the compound
may be a compound having a structure where at least one of
R.sub.201 to R.sub.203 in the compound represented by formula (ZI)
is bonded to at least one of R.sub.201 to R.sub.203 in another
compound represented by formula (ZI).
[0360] The component (ZI) is more preferably a compound (ZI-1),
(ZI-2) or (ZI-3) described below.
[0361] The compound (ZI-1) is an arylsulfonium compound where at
least one of R.sub.201 to R.sub.203 in formula (ZI) is an aryl
group, that is, a compound having an arylsulfonium as the
cation.
[0362] In the arylsulfonium compound, R.sub.201 to R.sub.203 all
may be an aryl group or a part of R.sub.201 to R.sub.203 may be an
aryl group with the remaining being an alkyl group or a cycloalkyl
group.
[0363] Examples of the arylsulfonium compound include a
triarylsulfonium compound, a diarylalkylsulfonium compound, an
aryldialkylsulfonium compound, a diarylcycloalkylsulfonium compound
and an aryldicycloalkylsulfonium compound.
[0364] The aryl group in the arylsulfonium compound is preferably
an aryl group such as phenyl group and naphthyl group, or a
heteroaryl group such as indole residue and pyrrole residue, more
preferably a phenyl group or an indole residue. In the case where
the arylsulfonium compound has two or more aryl groups, these two
or more aryl groups may be the same or different.
[0365] The alkyl group which is present, if desired, in the
arylsulfonium compound is preferably a linear or branched alkyl
group having a carbon number of 1 to 15, and examples thereof
include a methyl group, an ethyl group, a propyl group, an n-butyl
group, a sec-butyl group and a tert-butyl group.
[0366] The cycloalkyl group which is present, if desired, in the
arylsulfonium compound is preferably a cycloalkyl group having a
carbon number of 3 to 15, and examples thereof include a
cyclopropyl group, a cyclobutyl group and a cyclohexyl group.
[0367] The aryl group, alkyl group and cycloalkyl group of
R.sub.201 to R.sub.203 each may have, as the substituent, an alkyl
group (for example, an alkyl group having a carbon number of 1 to
15), a cycloalkyl group (for example, a cycloalkyl group having a
carbon number of 3 to 15), an aryl group (for example, an aryl
group having a carbon number of 6 to 14), an alkoxy group (for
example, an alkoxy group having a carbon number of 1 to 15), a
halogen atom, a hydroxyl group or a phenylthio group. The
substituent is preferably a linear or branched alkyl group having a
carbon number of 1 to 12, a cycloalkyl group having a carbon number
of 3 to 12, or a linear, branched or cyclic alkoxy group having a
carbon number of 1 to 12, more preferably an alkyl group having a
carbon number of 1 to 4 or an alkoxy group having a carbon number
of 1 to 4. The substituent may be substituted to any one of three
members R.sub.201 to R.sub.203 or may be substituted to all of
these three members. In the case where R.sub.201 to R.sub.203 are
an aryl group, the substituent is preferably substituted at the
p-position of the aryl group.
[0368] The compound (ZI-2) is described below. The compound (ZI-2)
is a compound where each of R.sub.201 to R.sub.203 in formula (ZI)
independently represents an aromatic ring-free organic group. The
aromatic ring as used herein includes an aromatic ring containing a
heteroatom.
[0369] The aromatic ring-free organic group as R.sub.201 to
R.sub.203 generally has a carbon number of 1 to 30, preferably from
1 to 20.
[0370] Each of R.sub.201 to R.sub.203 is independently preferably
an alkyl group, a cycloalkyl group, an allyl group or a vinyl
group, more preferably a linear, branched or cyclic 2-oxoalkyl
group or an alkoxycarbonylmethyl group, still more preferably a
linear or branched 2-oxoalkyl group.
[0371] The alkyl group as R.sub.201 to R.sub.203 may be either
linear or branched and includes a linear or branched alkyl group
preferably having a carbon number of 1 to 10 (e.g., methyl, ethyl,
propyl, butyl, pentyl). The alkyl group as R.sub.201 to R.sub.203
is preferably a linear or branched 2-oxoalkyl group or an
alkoxycarbonylmethyl group.
[0372] The cycloalkyl group as R.sub.201 to R.sub.203 includes a
cycloalkyl group preferably having a carbon number of 3 to 10
(e.g., cyclopentyl, cyclohexyl, norbornyl). The cycloalkyl group as
R.sub.201 to R.sub.203 is preferably a cyclic 2-oxoalkyl group.
[0373] The linear, branched or cyclic 2-oxoalkyl group as R.sub.201
to R.sub.203 is preferably a group having >C.dbd.O at the
2-position of the above-described alkyl or cycloalkyl group.
[0374] The alkoxy group in the alkoxycarbonylmethyl group as
R.sub.201 to R.sub.203 includes an alkoxy group preferably having a
carbon number of 1 to 5 (e.g., methoxy, ethoxy, propoxy, butoxy,
pentoxy).
[0375] R.sub.201 to R.sub.203 each may be further substituted by a
halogen atom, an alkoxy group (for example, an alkoxy group having
a carbon number of 1 to 5), a hydroxyl group, a cyano group or a
nitro group.
[0376] The compound (ZI-3) is a compound represented by the
following formula (ZI-3), and this is a compound having a
phenacylsulfonium salt structure.
##STR00042##
[0377] In formula (ZI-3), each of R.sub.1c to R.sub.5c
independently represents a hydrogen atom, an alkyl group, a
cycloalkyl group, an alkoxy group or a halogen atom.
[0378] Each of R.sub.6c and R.sub.7c independently represents a
hydrogen atom, an alkyl group or a cycloalkyl group.
[0379] Each of R.sub.x and R.sub.y independently represents an
alkyl group, a cycloalkyl group, an allyl group or a vinyl
group.
[0380] Any two or more members out of R.sub.1c to R.sub.7c, and a
pair of R.sub.x and R.sub.y, may combine with each other to form a
ring structure, respectively, and the ring structure may contain an
oxygen atom, a sulfur atom, an ester bond or an amide bond.
Examples of the group formed by combining any two or more members
out of R.sub.1c to R.sub.7c or a pair of R.sub.x and R.sub.y
include a butylene group and a pentylene group.
[0381] X.sup.- represents a non-nucleophilic anion, and examples
thereof are the same as those of the non-nucleophilic anion of
X.sup.- in formula (ZI).
[0382] The alkyl group as R.sub.1c to R.sub.7c may be linear or
branched and includes, for example, a linear or branched alkyl
group having a carbon number of 1 to 20, preferably a linear or
branched alkyl group having a carbon number of 1 to 12 (such as
methyl group, ethyl group, linear or branched propyl group, linear
or branched butyl group and linear or branched pentyl group).
[0383] The cycloalkyl group as R.sub.1c to R.sub.7c includes a
cycloalkyl group preferably having a carbon number of 3 to 8 (e.g.,
cyclopentyl, cyclohexyl).
[0384] The alkoxy group as R.sub.1c to R.sub.5c may be linear,
branched or cyclic and includes, for example, an alkoxy group
having a carbon number of 1 to 10, preferably a linear or branched
alkoxy group having a carbon number of 1 to 5 (such as methoxy
group, ethoxy group, linear or branched propoxy group, linear or
branched butoxy group and linear or branched pentoxy group), and a
cyclic alkoxy group having a carbon number of 3 to 8 (e.g.,
cyclopentyloxy, cyclohexyloxy).
[0385] A compound where any one of R.sub.1c to R.sub.5c is a linear
or branched alkyl group, a cycloalkyl group or a linear, branched
or cyclic alkoxy group is preferred, and a compound where the sum
of carbon numbers of R.sub.1c to R.sub.5c is from 2 to 15 is more
preferred. Thanks to this construction, the solubility in a solvent
is more enhanced and generation of particles during storage is
suppressed.
[0386] The alkyl group as Rx and R.sub.y is the same as the alkyl
group of R.sub.1c to R.sub.7c. The alkyl group as R.sub.x and
R.sub.y is preferably a linear or branched 2-oxoalkyl group or an
alkoxycarbonylmethyl group.
[0387] The cycloalkyl group as R.sub.x and R.sub.y is the same as
the cycloalkyl group of R.sub.1c to R.sub.7c. The cycloalkyl group
as R.sub.x and R.sub.y is preferably a cyclic 2-oxoalkyl group.
[0388] The linear, branched or cyclic 2-oxoalkyl group includes a
group having >C.dbd.O at the 2-position of the alkyl group or
cycloalkyl group of R.sub.1c to R.sub.7.
[0389] The alkoxy group in the alkoxycarbonylmethyl group is the
same as the alkoxy group of R.sub.1c to R.sub.5c.
[0390] R.sub.x and R.sub.y each is preferably an alkyl group having
a carbon number of 4 or more, more preferably 6 or more, still more
preferably 8 or more.
[0391] In formulae (ZII) and (ZIII), each of R.sub.204 to R.sub.207
independently represents an aryl group, an alkyl group or a
cycloalkyl group.
[0392] The aryl group of R.sub.204 to R.sub.207 is preferably a
phenyl group or a naphthyl group, more preferably a phenyl
group.
[0393] The alkyl group as R.sub.204 to R.sub.207 may be linear or
branched and includes a linear or branched alkyl group preferably
having a carbon number of 1 to 10 (e.g., methyl, ethyl, propyl,
butyl, pentyl).
[0394] The cycloalkyl group as R.sub.204 to R.sub.207 includes a
cycloalkyl group preferably having a carbon number of 3 to 10
(e.g., cyclopentyl, cyclohexyl, norbornyl).
[0395] R.sub.204 to R.sub.207 each may have a substituent. Examples
of the substituent which R.sub.204 to R.sub.207 each may have
include an alkyl group (for example, an alkyl group having a carbon
number of 1 to 15), a cycloalkyl group (for example, a cycloalkyl
group having a carbon number of 3 to 15), an aryl group (for
example, an aryl group having a carbon number of 6 to 15), an
alkoxy group (for example, an alkoxy group having a carbon number
of 1 to 15), a halogen atom, a hydroxyl group and a phenylthio
group.
[0396] X.sup.- represents a non-nucleophilic anion and is the same
as the non-nucleophilic anion of X.sup.- in formula (ZI).
[0397] Out of the compounds capable of generating an acid upon
irradiation with an actinic ray or radiation, preferred compounds
further include the compounds represented by the following formulae
(ZIV), (ZV) and (ZVI):
##STR00043##
[0398] In formulae (ZIV) to (ZVI), each of Ar.sub.3 and Ar.sub.4
independently represents an aryl group.
[0399] R.sub.208 represents an alkyl group or an aryl group.
[0400] Each of R.sub.209 and R.sub.210 independently represents an
alkyl group, an aryl group or an electron-withdrawing group.
[0401] R.sub.208 is preferably an aryl group.
[0402] R.sub.209 is preferably an electron-withdrawing group, more
preferably a cyano group or a fluoroalkyl group.
[0403] A represents an alkylene group, an alkenylene group or an
arylene group.
[0404] The compound capable of generating an acid upon irradiation
with an actinic ray or radiation is preferably a compound
represented by any one of formulae (ZI) to (ZIII).
[0405] The compound (B) is preferably a compound capable of
generating a fluorine atom-containing aliphatic sulfonic acid or a
fluorine atom-containing benzenesulfonic acid upon irradiation with
an actinic ray or radiation.
[0406] The compound (B) preferably has a triphenylsulfonium
structure.
[0407] The compound (B) is preferably a triphenylsulfonium salt
compound having a fluorine-unsubstituted alkyl or cycloalkyl group
in the cation moiety.
[0408] Particularly preferred examples out of the compounds capable
of generating an acid upon irradiation with an actinic ray or
radiation are set forth below.
##STR00044## ##STR00045## ##STR00046## ##STR00047## ##STR00048##
##STR00049## ##STR00050## ##STR00051## ##STR00052##
##STR00053##
[0409] One of these photo-acid generators may be used alone, or two
or more kinds thereof may be used in combination. In the case of
using two or more kinds of photo-acid generators in combination,
compounds capable of generating two kinds of organic acids
differing in the total atom number except for hydrogen atom by 2 or
more are preferably combined.
[0410] The content of the photo-acid generator is preferably from
0.1 to 20 mass %, more preferably from 0.5 to 10 mass %, still more
preferably from 1 to 7 mass %, based on the entire solid content of
the resist composition.
(C) Solvent
[0411] Examples of the solvent which can be used for dissolving
respective components described above to prepare a positive tone
resist composition include an organic solvent such as alkylene
glycol monoalkyl ether carboxylate, alkylene glycol monoalkyl
ether, alkyl lactate, alkyl alkoxypropionate, cyclic lactone having
a carbon number of 4 to 10, monoketone compound having a carbon
number of 4 to 10 which may contain a ring, alkylene carbonate,
alkyl alkoxyacetate and alkyl pyruvate.
[0412] Preferred examples of the alkylene glycol monoalkyl ether
carboxylate include propylene glycol monomethyl ether acetate,
propylene glycol monoethyl ether acetate, propylene glycol
monopropyl ether acetate, propylene glycol monobutyl ether acetate,
propylene glycol monomethyl ether propionate, propylene glycol
monoethyl ether propionate, ethylene glycol monomethyl ether
acetate and ethylene glycol monoethyl ether acetate.
[0413] Preferred examples of the alkylene glycol monoalkyl ether
include propylene glycol monomethyl ether, propylene glycol
monoethyl ether, propylene glycol monopropyl ether, propylene
glycol monobutyl ether, ethylene glycol monomethyl ether and
ethylene glycol monoethyl ether.
[0414] Preferred examples of the alkyl lactate include methyl
lactate, ethyl lactate, propyl lactate and butyl lactate.
[0415] Preferred examples of the alkyl alkoxypropionate include
ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, methyl
3-ethoxypropionate and ethyl 3-methoxypropionate.
[0416] Preferred examples of the cyclic lactone having a carbon
number of 4 to 10 include .beta.-propiolactone,
.beta.-butyrolactone, .gamma.-butyrolactone,
.alpha.-methyl-.gamma.-butyrolactone,
.beta.-methyl-.gamma.-butyrolactone, .gamma.-valerolactone,
.gamma.-caprolactone, .gamma.-octanoic lactone and
.alpha.-hydroxy-.gamma.-butyrolactone.
[0417] Preferred examples of the monoketone compound having a
carbon number of 4 to 10 which may contain a ring include
2-butanone, 3-methylbutanone, pinacolone, 2-pentanone, 3-pentanone,
3-methyl-2-pentanone, 4-methyl-2-pentanone, 2-methyl-3-pentanone,
4,4-dimethyl-2-pentanone, 2,4-dimethyl-3-pentanone,
2,2,4,4-tetramethyl-3-pentanone, 2-hexanone, 3-hexanone,
5-methyl-3-hexanone, 2-heptanone, 3-heptanone, 4-heptanone,
2-methyl-3-heptanone, 5-methyl-3-heptanone,
2,6-dimethyl-4-heptanone, 2-octanone, 3-octanone, 2-nonanone,
3-nonanone, 5-nonanone, 2-decanone, 3-decanone, 4-decanone,
5-hexen-2-one, 3-penten-2-one, cyclopentanone,
2-methylcyclopentanone, 3-methylcyclopentanone,
2,2-dimethylcyclopentanone, 2,4,4-trimethylcyclopentanone,
cyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone,
4-ethylcyclohexanone, 2,2-dimethylcyclohexanone,
2,6-dimethylcyclohexanone, 2,2,6-trimethylcyclohexanone,
cycloheptanone, 2-methylcycloheptanone and
3-methylcycloheptanone.
[0418] Preferred examples of the alkylene carbonate include
propylene carbonate, vinylene carbonate, ethylene carbonate and
butylene carbonate.
[0419] Preferred examples of the alkyl alkoxyacetate include
2-methoxyethyl acetate, 2-ethoxyethyl acetate,
2-(2-ethoxyethoxy)ethyl acetate, 3-methoxy-3-methylbutyl acetate
and 1-methoxy-2-propyl acetate.
[0420] Preferred examples of the alkyl pyruvate include methyl
pyruvate, ethyl pyruvate and propyl pyruvate.
[0421] The solvent which can be preferably used is a solvent having
a boiling point of 130.degree. C. or more at ordinary temperature
under atmospheric pressure, and specific examples thereof include
cyclopentanone, .gamma.-butyrolactone, cyclohexanone, ethyl
lactate, ethylene glycol monoethyl ether acetate, propylene glycol
monomethyl ether acetate, ethyl 3-ethoxypropionate, ethyl pyruvate,
2-ethoxyethyl acetate, 2-(2-ethoxyethoxy)ethyl acetate and
propylene carbonate.
[0422] In the present invention, one of these solvents may be used
alone, or two or more kinds thereof may be used in combination.
[0423] In the present invention, a mixed solvent prepared by mixing
a solvent containing a hydroxyl group in the structure and a
solvent not containing a hydroxyl group may be used as the organic
solvent.
[0424] Examples of the solvent containing a hydroxyl group include
ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol
monoethyl ether, propylene glycol, propylene glycol monomethyl
ether, propylene glycol monoethyl ether and ethyl lactate. Among
these, propylene glycol monomethyl ether and ethyl lactate are
preferred.
[0425] Examples of the solvent not containing a hydroxyl group
include propylene glycol monomethyl ether acetate, ethyl
ethoxypropionate, 2-heptanone, .gamma.-butyrolactone,
cyclohexanone, butyl acetate, N-methylpyrrolidone,
N,N-dimethylacetamide and dimethylsulfoxide. Among these, propylene
glycol monomethyl ether acetate, ethyl ethoxypropionate,
2-heptanone, .gamma.-butyrolactone, cyclohexanone and butyl acetate
are preferred, and propylene glycol monomethyl ether acetate, ethyl
ethoxypropionate and 2-heptanone are most preferred.
[0426] The mixing ratio (by mass) between the solvent containing a
hydroxyl group and the solvent not containing a hydroxyl group is
from 1/99 to 99/1, preferably from 10/90 to 90/10, more preferably
from 20/80 to 60/40. A mixed solvent in which the solvent not
containing a hydroxyl group is contained in an amount of 50 mass %
or more is preferred in view of coating uniformity.
[0427] The solvent is preferably a mixed solvent of two or more
kinds of solvents including propylene glycol monomethyl ether
acetate.
[0428] The entire solid content concentration in the resist
composition is generally from 1 to 10 mass %, preferably from 1 to
8.0 mass %, more preferably from 1.0 to 6.0 mass %. (D) Resin
having at least either a fluorine atom or a silicon atom
[0429] The resist composition of the present invention preferably
contains (D) a resin having at least either a fluorine atom or a
silicon atom.
[0430] In the resin (D), the fluorine atom or silicon atom may be
present in the main chain of the resin or may be substituted to the
side chain.
[0431] The resin (D) is preferably a resin having a fluorine
atom-containing alkyl group, a fluorine atom-containing cycloalkyl
group or a fluorine atom-containing aryl group, as a fluorine
atom-containing partial structure.
[0432] The fluorine atom-containing alkyl group (preferably having
a carbon number of 1 to 10, more preferably from 1 to 4) is a
linear or branched alkyl group with at least one hydrogen atom
being substituted by a fluorine atom and may further have another
substituent.
[0433] The fluorine atom-containing cycloalkyl group is a
monocyclic or polycyclic cycloalkyl group with at least one
hydrogen atom being substituted by a fluorine atom and may further
have another substituent.
[0434] The fluorine atom-containing aryl group is an aryl group
(e.g., phenyl, naphthyl) with at least one hydrogen atom being
substituted by a fluorine atom and may further have another
substituent.
[0435] Specific examples of the fluorine atom-containing alkyl
group, fluorine atom-containing cycloalkyl group and fluorine
atom-containing aryl group are set forth below, but the present
invention is not limited thereto.
##STR00054##
[0436] In formulae (f1) to (f3), each of R.sub.57 to R.sub.68
independently represents a hydrogen atom, a fluorine atom or an
alkyl group, provided that at least one of R.sub.57 to R.sub.61, at
least one of R.sub.62 to R.sub.64 and at least one of R.sub.65 to
R.sub.68 are a fluorine atom or an alkyl group (preferably having a
carbon number of 1 to 4) with at least one hydrogen atom being
substituted by a fluorine atom. It is preferred that R.sub.57 to
R.sub.61 and R.sub.65 to R.sub.67 all are a fluorine atom. Each of
R.sub.62, R.sub.63 and R.sub.68 is preferably an alkyl group
(preferably having a carbon number of 1 to 4) with at least one
hydrogen atom being substituted by a fluorine atom, more preferably
a perfluoroalkyl group having a carbon number of 1 to 4. R.sub.62
and R.sub.63 may combine with each other to form a ring.
[0437] Specific examples of the group represented by formula (f1)
include p-fluorophenyl group, pentafluorophenyl group and
3,5-di(trifluoromethyl)phenyl group.
[0438] Specific examples of the group represented by formula (f2)
include trifluoroethyl group, pentafluoropropyl group,
pentafluoroethyl group, heptafluorobutyl group, hexafluoroisopropyl
group, heptafluoroisopropyl group, hexafluoro(2-methyl)isopropyl
group, nonafluorobutyl group, octafluoroisobutyl group,
nonafluorohexyl group, nonafluoro-tert-butyl group,
perfluoroisopentyl group, perfluorooctyl group,
perfluoro(trimethyl)hexyl group, 2,2,3,3-tetrafluorocyclobutyl
group and perfluorocyclohexyl group. Among these,
hexafluoroisopropyl group, heptafluoroisopropyl group,
hexafluoro(2-methyl)isopropyl group, octafluoroisobutyl group,
nonafluoro-tert-butyl group and perfluoroisopentyl group are
preferred, and hexafluoroisopropyl group and heptafluoroisopropyl
group are more preferred.
[0439] Specific examples of the group represented by formula (f3)
include --C(CF.sub.3).sub.2OH, --C(C.sub.2F.sub.5).sub.2OH,
--C(CF.sub.3)(CH.sub.3)OH and --CH(CF.sub.3)OH, with
--C(CF.sub.3).sub.2OH being preferred.
[0440] The resin (D) is preferably a resin having an alkylsilyl
structure (preferably a trialkylsilyl group) or a cyclic siloxane
structure, as a silicon atom-containing partial structure.
[0441] Specific examples of the alkylsilyl structure and cyclic
siloxane structure include the groups represented by the following
formulae (CS-1) to (CS-3):
##STR00055##
[0442] In formulae (CS-1) to (CS-3), each of R.sub.12 to R.sub.26
independently represents a linear or branched alkyl group
(preferably having a carbon number of 1 to 20) or a cycloalkyl
group (preferably having a carbon number of 3 to 20).
[0443] Each of L.sub.3 to L.sub.5 represents a single bond or a
divalent linking group. The divalent linking group is a sole group
or a combination of two or more groups selected from the group
consisting of an alkylene group, a phenylene group, an ether group,
a thioether group, a carbonyl group, an ester group, an amide
group, a urethane group and a ureylene group.
[0444] n represents an integer of 1 to 5.
[0445] The resin (D) includes a resin containing at least one
member selected from the group consisting of repeating units
represented by the following formulae (C-I) to (C-V):
##STR00056##
[0446] In formulae (C-I) to (C-V), each of R.sub.1 to R.sub.3
independently represents a hydrogen atom, a fluorine atom, a linear
or branched alkyl group having a carbon number of 1 to 4, or a
linear or branched fluorinated alkyl group having a carbon number
of 1 to 4.
[0447] Each of W.sub.1 and W.sub.2 represents an organic group
having at least either a fluorine atom or a silicon atom.
[0448] Each R.sub.4 to R.sub.7 independently represents a hydrogen
atom, a fluorine atom, a linear or branched alkyl group having a
carbon number of 1 to 4, or a linear or branched fluorinated alkyl
group having a carbon number of 1 to 4, provided that at least one
of R.sub.4 to R.sub.7 represents a fluorine atom. R.sub.4 and
R.sub.5, or R.sub.6 and R.sub.7 may form a ring.
[0449] R.sub.8 represents a hydrogen atom or a linear or branched
alkyl group having a carbon number of 1 to 4.
[0450] R.sub.9 represents a linear or branched alkyl group having a
carbon number of 1 to 4, or a linear or branched fluorinated alkyl
group having a carbon number of 1 to 4.
[0451] Each of L.sub.1 and L.sub.2 represents a single bond or a
divalent linking group and is the same as L.sub.3 to L.sub.5
above.
[0452] Q represents a monocyclic or polycyclic aliphatic group,
that is, an atomic group for forming an alicyclic structure,
including the two bonded carbon atoms (C--C).
[0453] Each of R.sub.30 and R.sub.31 independently represents a
hydrogen or fluorine atom.
[0454] Each of R.sub.32 and R.sub.33 independently represents an
alkyl group, a cycloalkyl group, a fluorinated alkyl group or a
fluorinated cycloalkyl group.
[0455] Here, the repeating unit represented by formula (C-V) has at
least one fluorine atom in at least one member out of R.sub.30,
R.sub.31, R.sub.32 and R.sub.33.
[0456] The resin (D) preferably has a repeating unit represented by
formula (C-I), more preferably a repeating unit represented by any
one of the following formulae (C-Ia) to (C-Id):
##STR00057##
[0457] In formulae (C-Ia) to (C-Id), each of R.sub.10 and R.sub.11
represents a hydrogen atom, a fluorine atom, a linear or branched
alkyl group having a carbon number of 1 to 4, or a linear or
branched fluorinated alkyl group having a carbon number of 1 to
4.
[0458] Each of W.sub.3 to W.sub.6 represents an organic group
having one or more atoms of at least either a fluorine atom or a
silicon atom.
[0459] When W.sub.1 to W.sub.6 are an organic group having a
fluorine atom, the organic group is preferably a fluorinated linear
or branched alkyl group or cycloalkyl group having a carbon number
of 1 to 20, or a fluorinated linear, branched or cyclic alkyl ether
group having a carbon number of 1 to 20.
[0460] Examples of the fluorinated alkyl group of W.sub.1 to
W.sub.6 include a trifluoroethyl group, a pentafluoropropyl group,
a hexafluoroisopropyl group, a hexafluoro(2-methyl)isopropyl group,
a heptafluorobutyl group, a heptafluoroisopropyl group, an
octafluoroisobutyl group, a nonafluorohexyl group, a
nonafluoro-tert-butyl group, a perfluoroisopentyl group, a
perfluorooctyl group and a perfluoro(trimethyl)hexyl group.
[0461] When W.sub.1 to W.sub.6 are an organic group having a
silicon atom, the organic group preferably has an alkylsilyl
structure or a cyclic siloxane structure. Specific examples thereof
include the groups represented by formulae (CS-1) to (CS-3).
[0462] Specific examples of the repeating unit represented by
formula (C-I) are set forth below. X represents a hydrogen atom,
--CH.sub.3, --F or --CF.sub.3.
##STR00058## ##STR00059## ##STR00060##
[0463] The resin (D) is preferably any one resin selected from the
following (D-1) to (D-6):
[0464] (D-1) a resin containing (a) a repeating unit having a
fluoroalkyl group (preferably having a carbon number of 1 to 4),
more preferably a resin containing only the repeating unit (a),
[0465] (D-2) a resin containing (b) a repeating unit having a
trialkylsilyl group or a cyclic siloxane structure, more preferably
a resin containing only the repeating unit (b),
[0466] (D-3) a resin containing (a) a repeating unit having a
fluoroalkyl group (preferably having a carbon number of 1 to 4) and
(c) a repeating unit having a branched alkyl group (preferably
having a carbon number of 4 to 20), a cycloalkyl group (preferably
having a carbon number of 4 to 20), a branched alkenyl group
(preferably having a carbon number of 4 to 20), a cycloalkenyl
group (preferably having a carbon number of 4 to 20) or an aryl
group (preferably having a carbon number of 6 to 20), more
preferably a copolymerization resin of the repeating unit (a) and
the repeating unit (c),
[0467] (D-4) a resin containing (b) a repeating unit having a
trialkylsilyl group or a cyclic siloxane structure and (c) a
repeating unit having a branched alkyl group (preferably having a
carbon number of 4 to 20), a cycloalkyl group (preferably having a
carbon number of 4 to 20), a branched alkenyl group (preferably
having a carbon number of 4 to 20), a cycloalkenyl group
(preferably having a carbon number of 4 to 20) or an aryl group
(preferably having a carbon number of 6 to 20), more preferably a
copolymerization resin of the repeating unit (b) and the repeating
unit (c),
[0468] (D-5) a resin containing (a) a repeating unit having a
fluoroalkyl group (preferably having a carbon number of 1 to 4) and
(b) a repeating unit having a trialkylsilyl group or a cyclic
siloxane structure, more preferably a copolymerization resin of the
repeating unit (a) and the repeating unit (b), and
[0469] (D-6) a resin containing (a) a repeating unit having a
fluoroalkyl group (preferably having a carbon number of 1 to 4),
(b) a repeating unit having a trialkylsilyl group or a cyclic
siloxane structure, and (c) a repeating unit having a branched
alkyl group (preferably having a carbon number of 4 to 20), a
cycloalkyl group (preferably having a carbon number of 4 to 20), a
branched alkenyl group (preferably having a carbon number of 4 to
20), a cycloalkenyl group (preferably having a carbon number of 4
to 20) or an aryl group (preferably having a carbon number of 6 to
20), more preferably a copolymerization resin of the repeating unit
(a), the repeating unit (b) and the repeating unit (c).
[0470] As for the repeating unit (c) having a branched alkyl group,
a cycloalkyl group, a branched alkenyl group, a cycloalkenyl group
or an aryl group in the resins (D-3), (D-4) and (D-6), an
appropriate functional group can be introduced considering the
hydrophilicity/hydrophobicity, interaction and the like, but in
view of followability of immersion liquid or receding contact
angle, a functional group having no polar group is preferred.
[0471] In the resins (D-3), (D-4) and (D-6), the content of the
repeating unit (a) having a fluoroalkyl group and/or the repeating
unit (b) having a trialkylsilyl group or a cyclic siloxane
structure is preferably from 20 to 99 mol %.
[0472] The resin (D) is preferably a resin having a repeating unit
represented by the following formula (Ia):
##STR00061##
[0473] In formula (Ia), Rf represents a fluorine atom or an alkyl
group with at least one hydrogen atom being substituted by a
fluorine atom.
[0474] R.sub.1 represents an alkyl group.
[0475] R.sub.2 represents a hydrogen atom or an alkyl group.
[0476] In formula (Ia), the alkyl group with at least one hydrogen
atom being substituted by a fluorine atom of Rf is preferably an
alkyl group having a carbon number of 1 to 3, more preferably a
trifluoromethyl group.
[0477] The alkyl group of R.sub.1 is preferably a linear or
branched alkyl group having a carbon number of 3 to 10, more
preferably a branched alkyl group having a carbon number of 3 to
10.
[0478] R.sub.2 is preferably a linear or branched alkyl group
having a carbon number of 1 to 10, more preferably a linear or
branched alkyl group having a carbon number of 3 to 10.
[0479] Specific examples of the repeating unit represented by
formula (Ia) are set forth below, but the present invention is not
limited thereto.
[0480] X.dbd.F or CF.sub.3
##STR00062## ##STR00063##
[0481] The repeating unit represented by formula (Ia) can be formed
by polymerizing a compound represented by the following formula
(I):
##STR00064##
[0482] In formula (I), Rf represents a fluorine atom or an alkyl
group with at least one hydrogen atom being substituted by a
fluorine atom.
[0483] R.sub.1 represents an alkyl group.
[0484] R.sub.2 represents a hydrogen atom or an alkyl group.
[0485] Rf, R.sub.1 and R.sub.2 in formula (I) have the same
meanings as Rf, R.sub.1 and R.sub.2 in formula (Ia).
[0486] As for the compound represented by formula (I), a
commercially available product or a compound synthesized may be
used. In the case of synthesizing the compound, this can be
attained by converting a 2-trifluoromethyl methacrylic acid into an
acid chloride and then esterifying the acid chloride.
[0487] The resin (D) containing a repeating unit represented by
formula (Ia) preferably further contains a repeating unit
represented by the following formula (III):
##STR00065##
[0488] In formula (III), R.sub.4 represents an alkyl group, a
cycloalkyl group, an alkenyl group, a cycloalkenyl group, a
trialkylsilyl group or a group having a cyclic siloxane
structure.
[0489] L.sub.6 represents a single bond or a divalent linking
group.
[0490] R represents a hydrogen atom or an alkyl group (which may be
substituted by a fluorine atom, etc.). The alkyl group represented
by R preferably has a carbon number of 1 to 4. R is preferably a
hydrogen atom, a methyl group or a trifluoromethyl group, and a
hydrogen atom and a methyl group are particularly preferred. In
formula (III), the alkyl group of R.sub.4 is preferably a linear or
branched alkyl group having a carbon number of 3 to 20.
[0491] The cycloalkyl group is preferably a cycloalkyl group having
a carbon number of 3 to 20.
[0492] The alkenyl group is preferably an alkenyl group having a
carbon number of 3 to 20.
[0493] The cycloalkenyl group is preferably a cycloalkenyl group
having a carbon number of 3 to 20.
[0494] The trialkylsilyl group is preferably a trialkylsilyl group
having a carbon number of 3 to 20.
[0495] The group having a cyclic siloxane structure is preferably a
group containing a cyclic siloxane structure having a carbon number
of 3 to 20.
[0496] The divalent linking group of L.sub.6 is preferably an
alkylene group (preferably having a carbon number of 1 to 5) or an
oxy group.
[0497] Specific examples of the resin (D) having a repeating unit
represented by formula (Ia) are set forth below, but the present
invention is not limited thereto.
##STR00066## ##STR00067## ##STR00068## ##STR00069##
##STR00070##
[0498] The resin (D) is preferably a resin containing a repeating
unit represented by the following formula (II) and a repeating unit
represented by the following formula (III):
##STR00071##
[0499] In formulae (II) and (III), Rf represents a fluorine atom or
an alkyl group with at least one hydrogen atom being substituted by
a fluorine atom.
[0500] R.sub.3 represents an alkyl group, a cycloalkyl group, an
alkenyl group, a cycloalkenyl group, or a group formed by combining
two or more members thereof.
[0501] R.sub.4 represents an alkyl group, a cycloalkyl group, an
alkenyl group, a cycloalkenyl group, a trialkylsilyl group, a group
having a cyclic siloxane structure, or a group formed by combining
two or more members thereof.
[0502] In the alkyl group, cycloalkyl group, alkenyl group,
cycloalkenyl group and trialkylsilyl group of R.sub.3 and R.sub.4,
a functional group can be introduced but in view of followability
of immersion liquid, a functional group having no polar group is
preferred, and an unsubstituted functional group is more
preferred.
[0503] R represents a hydrogen atom or an alkyl group (which may be
substituted by a fluorine atom, etc.). The alkyl group represented
by R preferably has a carbon number of 1 to 4. R is preferably a
hydrogen atom, a methyl group or a trifluoromethyl group, and a
hydrogen atom and a methyl group are particularly preferred.
[0504] L.sub.6 represents a single bond or a divalent linking
group.
[0505] 0<m<100.
[0506] 0<n<100.
[0507] In formula (II), Rf has the same meaning as Rf in formula
(Ia).
[0508] The alkyl group of R.sub.3 is preferably a linear or
branched alkyl group having a carbon number of 3 to 20.
[0509] The cycloalkyl group is preferably a cycloalkyl group having
a carbon number of 3 to 20.
[0510] The alkenyl group is preferably an alkenyl group having a
carbon number of 3 to 20.
[0511] The cycloalkenyl group is preferably a cycloalkenyl group
having a carbon number of 3 to 20.
[0512] L.sub.6 is preferably a single bond, a methylene group, an
ethylene group or an ether group.
[0513] m and n are preferably from 30 to 70 and from 30 to 70,
respectively, more preferably from 40 to 60 and from 40 to 60,
respectively.
[0514] Specific examples of the resin (D) containing a repeating
unit represented by formula (II) and a repeating unit represented
by formula (III) are set forth below, but the present invention is
not limited thereto.
##STR00072## ##STR00073## ##STR00074## ##STR00075##
[0515] The resin (D) may contain a repeating unit represented by
the following formula (VIII):
##STR00076##
[0516] In formula (VIII), Z.sub.2 represents --O-- or
--N(R.sub.41)--. R.sub.41 represents a hydrogen atom, an alkyl
group or --OSO.sub.2--R.sub.42. R.sub.42 represents an alkyl group,
a cycloalkyl group or a camphor residue. The alkyl group of
R.sub.41 and R.sub.42 may be substituted by a halogen atom
(preferably fluorine atom) or the like.
[0517] The resin (D) is preferably solid at ordinary temperature
(25.degree. C.). Furthermore, the glass transition temperature (Tg)
is preferably from 50 to 200.degree. C., more preferably from 80 to
160.degree. C.
[0518] When the resin is solid at 25.degree. C., this means that
the melting point is 25.degree. C. or more.
[0519] The glass transition temperature (Tg) can be measured by a
scanning calorimeter (Differential Scanning Calorimeter). For
example, the glass transition temperature can be measured by once
heating and then cooling the sample, again raising the temperature
at 5.degree. C./min, and analyzing the value when the specific
volume is changed.
[0520] The resin (D) is preferably stable to an acid and insoluble
in an alkali developer.
[0521] In view of followability of immersion liquid, the resin (D)
preferably contains none of (x) an alkali-soluble group, (y) a
group capable of decomposing by the action of an alkali (alkali
developer) to increase the solubility in an alkali developer, and
(z) a group capable of decomposing by the action of an acid to
increase the solubility in a developer.
[0522] In the resin (D), the total amount of repeating units having
an alkali-soluble group or a group whose solubility in a developer
increases by the action of an acid or alkali is preferably 20 mol %
or less, more preferably from 0 to 10 mol %, still more preferably
from 0 to 5 mol %, based on all repeating units constituting the
resin (D).
[0523] Also, unlike a surfactant generally used for resists, the
resin (D) does not have an ionic bond or a hydrophilic group such
as (poly(oxyalkylene)) group. If the resin (D) contains a
hydrophilic polar group, the followability of immersion water tends
to decrease. Therefore, it is more preferred not to contain a polar
group selected from a hydroxyl group, alkylene glycols and a
sulfone group. Furthermore, an ether group bonded to the carbon
atom of the main chain through a linking group is preferably not
contained because the hydrophilicity increases and the
followability of immersion liquid deteriorates. On the other hand,
an ether group bonded directly to the carbon atom of the main chain
as in formula (III) can sometimes express activity as a hydrophobic
group and is preferred.
[0524] Examples of the alkali-soluble group (x) include groups
having a phenolic hydroxyl group, a carboxylic acid group, a
fluorinated alcohol group, a sulfonic acid group, a sulfonamide
group, a sulfonylimide group, an
(alkylsulfonyl)(alkylcarbonyl)methylene group, an
(alkylsulfonyl)(alkylcarbonyl)imide group, a
bis(alkylcarbonyl)methylene group, a bis(alkylcarbonyl)imide group,
a bis(alkylsulfonyl)methylene group, a bis(alkylsulfonyl)imide
group, a tris(alkylcarbonyl)methylene group or a
tris(alkylsulfonyl)methylene group.
[0525] Examples of the group (y) capable of decomposing by the
action of an alkali (alkali developer) to increase the solubility
in an alkali developer include a lactone group, an ester group, a
sulfonamide group, an acid anhydride and an acid imide group.
[0526] Examples of the group (z) capable of decomposing by the
action of an acid to increase the solubility in a developer include
the same groups as those of the acid-decomposable group in the
acid-decomposable resin (A).
[0527] However, the repeating unit represented by the following
formula (pA-c) is not or scarcely decomposed by the action of an
acid as compared with the acid-decomposable group of the resin (A)
and is regarded as substantially non-acid-decomposable.
##STR00077##
[0528] In formula (pA-c), R.sub.p2 represents a hydrocarbon group
having a tertiary carbon atom bonded to the oxygen atom in the
formula.
[0529] In the case where the resin (D) contains a silicon atom, the
silicon atom content is preferably from 2 to 50 mass %, more
preferably from 2 to 30 mass %, based on the molecular weight of
the resin (D). Also, the silicon atom-containing repeating unit
preferably occupies from 10 to 100 mass %, more preferably from 20
to 100 mass %, in the resin (D).
[0530] In the case where the resin (D) contains a fluorine atom,
the fluorine atom content is preferably from 5 to 80 mass %, more
preferably from 10 to 80 mass %, based on the molecular weight of
the resin (D). Also, the fluorine atom-containing repeating unit
preferably occupies from 10 to 100 mass %, more preferably from 30
to 100 mass %, in the resin (D).
[0531] The standard polystyrene-reduced weight average molecular of
the resin (D) is preferably from 1,000 to 100,000, more preferably
from 1,000 to 50,000, still more preferably from 2,000 to 15,000,
yet still more preferably from 3,000 to 15,000.
[0532] The residual monomer amount in the resin (D) is preferably
from 0 to 10 mass %, more preferably from 0 to 5 mass %, still more
preferably from 0 to 1 mass %. Also, in view of the resolution,
resist profile, and side wall, roughness or the like of the resist
pattern, the molecular weight distribution (Mw/Mn, also called
dispersity) is preferably from 1 to 5, more preferably from 1 to 3,
still more preferably from 1 to 1.5.
[0533] The amount added of the resin (D) in the resist composition
is preferably from 0.1 to 20 mass %, more preferably from 0.1 to 10
mass %, still more preferably from 0.1 to 5 mass %, even still more
preferably from 0.2 to 3.0 mass %, yet even still more preferably
from 0.3 to 2.0 mass %, based on the entire solid content of the
resist composition.
[0534] In the resin (D), similarly to the acid-decomposable resin
(A), impurities such as metal are of course little contained and as
well, the content of residual monomers or oligomer components is
preferably not more than a specific value, for example, 0.1 mass %
by HPLC. By satisfying these conditions, not only the resist can be
improved in the sensitivity, resolution, process stability, pattern
profile and the like but also a resist free from extraneous
substances in liquid or change with aging in the sensitivity and
the like can be obtained.
[0535] As for the resin (D), various commercially available
products may be used or the resin may be synthesize by an ordinary
method (for example, radical polymerization)). Examples of the
synthesis method in general include a batch polymerization method
of dissolving monomer species and an initiator in a solvent and
heating the solution, thereby effecting the polymerization, and a
dropping polymerization method of adding dropwise a solution
containing monomer species and an initiator to a heated solvent
over 1 to 10 hours. A dropping polymerization method is preferred.
Examples of the reaction solvent include tetrahydrofuran,
1,4-dioxane, ethers such as diisopropyl ether, ketones such as
methyl ethyl ketone and methyl isobutyl ketone, an ester solvent
such as ethyl acetate, an amide solvent such as dimethylformamide
and dimethylacetamide, and the later-described solvent capable of
dissolving the composition of the present invention, such as
propylene glycol monomethyl ether acetate, propylene glycol
monomethyl ether and cyclohexanone. The polymerization is more
preferably performed using the same solvent as the solvent used in
the resist composition of the present invention. By the use of this
solvent, generation of particles during storage can be
suppressed.
[0536] The polymerization reaction is preferably performed in an
inert gas atmosphere such as nitrogen and argon. As for the
polymerization initiator, the polymerization is started using a
commercially available radical initiator (e.g., azo-based
initiator, peroxide). The radical initiator is preferably an
azo-based initiator, and an azo-based initiator having an ester
group, a cyano group or a carboxyl group is preferred. Preferred
examples of the initiator include azobisisobutyronitrile,
azobisdimethylvaleronitrile and dimethyl
2,2'-azobis(2-methylpropionate). A chain transfer agent may also be
used, if desired. The reaction concentration is usually from 5 to
50 mass %, preferably from 20 to 50 mass %, more preferably from 30
to 50 mass %, and the reaction temperature is usually from 10 to
150.degree. C., preferably from 30 to 120.degree. C., more
preferably from 60 to 100.degree. C.
[0537] After the completion of reaction, the reaction product is
allowed to cool to room temperature and purified. The purification
may be performed by a normal method, for example, a liquid-liquid
extraction method of combining water washing with an appropriate
solvent to remove residual monomers or oligomer components; a
purification method in a solution sate, such as ultrafiltration of
extracting and removing only polymers having a molecular weight
lower than a specific molecular weight; a reprecipitation method of
adding dropwise the resin solution in a poor solvent to solidify
the resin in the poor solvent and thereby remove residual monomers
and the like; or a purification method in a solid state, such as
washing of the resin slurry with a poor solvent after separation by
filtration. For example, the resin is precipitated as a solid
through contact with a solvent in which the resin is sparingly
soluble or insoluble (poor solvent) and which is in a volume amount
of 10 times or less, preferably from 10 to 5 times, the reaction
solution.
[0538] The solvent used at the operation of precipitation or
reprecipitation from the polymer solution (precipitation or
reprecipitation solvent) may be sufficient if it is a poor solvent
for the polymer, and the solvent used may be appropriately selected
according to the kind of the polymer from, for example, a
hydrocarbon (an aliphatic hydrocarbon such as pentane, hexane,
heptane and octane; an alicyclic hydrocarbon such as cyclohexane
and methylcyclohexane; and an aromatic hydrocarbon such as benzene,
toluene and xylene), a halogenated hydrocarbon (a halogenated
aliphatic hydrocarbon such as methylene chloride, chloroform and
carbon tetrachloride; and a halogenated aromatic hydrocarbon such
as chlorobenzene and dichlorobenzene), a nitro compound (e.g.,
nitromethane, nitroethane), a nitrile (e.g., acetonitrile,
benzonitrile), an ether (a chain ether such as diethyl ether,
diisopropyl ether and dimethoxyethane; and a cyclic ether such as
tetrahydrofuran and dioxane), a ketone (e.g., acetone, methyl ethyl
ketone, diisobutyl ketone), an ester (e.g., ethyl acetate, butyl
acetate), a carbonate (e.g., dimethyl carbonate, diethyl carbonate,
ethylene carbonate, propylene carbonate), an alcohol (e.g.,
methanol, ethanol, propanol, isopropyl alcohol, butanol), a
carboxylic acid (e.g., acetic acid), water, and a mixed solvent
containing such a solvent.
[0539] Among these, the precipitation or reprecipitation solvent is
preferably a solvent containing at least an alcohol (particularly
methanol or the like) or water. In such a solvent containing at
least a hydrocarbon, the ratio of the alcohol (particularly
methanol or the like) to other solvents (for example, an ester such
as ethyl acetate, and ethers such as tetrahydrofuran) is
approximately, for example, the former/the latter (volume ratio, at
25.degree. C.)=from 10/90 to 99/1, preferably the former/the latter
(volume ratio, at 25.degree. C.)=from 30/70 to 98/2, more
preferably the former/the latter (volume ratio, at 25.degree.
C.)=from 50/50 to 97/3.
[0540] The amount of the precipitation or reprecipitation solvent
used may be appropriately selected by taking into account the
efficiency, yield and the like, but in general, the amount used is
from 100 to 10,000 parts by mass, preferably from 200 to 2,000
parts by mass, more preferably from 300 to 1,000 parts by mass, per
100 parts by mass of the polymer solution.
[0541] The nozzle bore diameter at the time of feeding the polymer
solution into a precipitation or reprecipitation solvent (poor
solvent) is preferably 4 mm.phi. or less (for example, from 0.2 to
4 mm.phi.), and the feeding rate (dropping rate) of the polymer
solution into the poor solvent is, for example, in terms of the
linear velocity, from 0.1 to 10 m/sec, preferably on the order of
0.3 to 5 m/sec.
[0542] The precipitation or reprecipitation operation is preferably
performed under stirring. Examples of the stirring blade which can
be used for stirring include a disc turbine, a fan turbine
(including paddle), a curved vane turbine, a feathering turbine, a
Pfaudler type, a bull margin type, an angled vane fan turbine, a
propeller, a multistage type, an anchor type (or horseshoe type), a
gate type, a double ribbon and a screw. The stirring is preferably
further performed for 10 minutes or more, more preferably 20
minutes or more, after the completion of feeding of the polymer
solution. If the stirring time is short, the monomer content in the
polymer particle may not be sufficiently reduced. The mixing and
stirring of the polymer solution and the poor solvent may also be
performed using a line mixer instead of the stirring blade.
[0543] The temperature at the precipitation or reprecipitation may
be appropriately selected by taking into account the efficiency or
operability, but the temperature is usually on the order of 0 to
50.degree. C., preferably in the vicinity of room temperature (for
example, approximately from 20 to 35.degree. C.). The precipitation
or reprecipitation operation may be performed using a commonly
employed mixing vessel such as stirring tank according to a known
method such as batch system and continuous system.
[0544] The precipitated or reprecipitated particulate polymer is
usually subjected to commonly employed solid-liquid separation such
as filtration and centrifugation, then dried and used. The
filtration is performed using a solvent-resistant filter element
preferably under pressure. The drying is performed under
atmospheric pressure or reduced pressure (preferably under reduced
pressure) at a temperature of approximately from 30 to 100.degree.
C., preferably on the order of 30 to 50.degree. C.
[0545] Incidentally, after the resin is once precipitated and
separated, the resin may be again dissolved in a solvent and then
put into contact with a solvent in which the resin is sparingly
soluble or insoluble.
[0546] More specifically, there may be used a method comprising,
after the completion of radical polymerization reaction,
precipitating a resin by bringing the polymer into contact with a
solvent in which the polymer is sparingly soluble or insoluble
(step a), separating the resin from the solution (step b), anew
dissolving the resin in a solvent to prepare a resin solution A
(step c), precipitating a resin solid by bringing the resin
solution A into contact with a solvent in which the resin is
sparingly soluble or insoluble and which is in a volume amount of
less than 10 times (preferably a volume amount of 5 times or less)
the resin solution A (step d), and separating the precipitated
resin (step e).
[0547] As for the solvent used at the preparation of the resin
solution A, a solvent similar to the solvent used for dissolving
the monomer at the polymerization reaction may be used, and the
solvent may be the same as or different from the solvent used at
the polymerization reaction.
(E) Basic Compound
[0548] The resist composition of the present invention preferably
contains (E) a basic compound for reducing the change of
performance with aging from exposure to heating.
[0549] Preferred examples of the basic compound include compounds
having a structure represented by any one of the following formulae
(A) to (E):
##STR00078##
[0550] In formulae (A) and (E), each of R.sup.200, R.sup.201 and
R.sup.202 which may be the same or different represents a hydrogen
atom, an alkyl group (preferably having a carbon number of 1 to
20), a cycloalkyl group (preferably having a carbon number of 3 to
20) or an aryl group (having a carbon number of 6 to 20), and
R.sup.201 and R.sup.202 may combine with each other to form a
ring.
[0551] As for the alkyl group, the alkyl group having a substituent
is preferably an aminoalkyl group having a carbon number of 1 to
20, a hydroxyalkyl group having a carbon number of 1 to 20, or a
cyanoalkyl group having a carbon number of 1 to 20.
[0552] Each of R.sup.203, R.sup.204, R.sup.205 and R.sup.206 which
may be the same or different represents an alkyl group having a
carbon number of 1 to 20.
[0553] The alkyl group in these formulae (A) and (E) is more
preferably unsubstituted.
[0554] Preferred examples of the compound include guanidine,
aminopyrrolidine, pyrazole, pyrazoline, piperazine,
aminomorpholine, aminoalkylmorpholine and piperidine. More
preferred examples of the compound include a compound having an
imidazole structure, a diazabicyclo structure, an onium hydroxide
structure, an onium carboxylate structure, a trialkylamine
structure, an aniline structure or a pyridine structure; an
alkylamine derivative having a hydroxyl group and/or an ether bond;
and an aniline derivative having a hydroxyl group and/or an ether
bond.
[0555] Examples of the compound having an imidazole structure
include imidazole, 2,4,5-triphenylimidazole and benzimidazole.
Examples of the compound having a diazabicyclo structure include
1,4-diazabicyclo[2,2,2]octane, 1,5-diazabicyclo[4,3,0]non-5-ene and
1,8-diazabicyclo[5,4,0]undec-7-ene. Examples of the compound having
an onium hydroxide structure include triarylsulfonium hydroxide,
phenacylsulfonium hydroxide and sulfonium hydroxide having a
2-oxoalkyl group, specifically, triphenylsulfonium hydroxide,
tris(tert-butylphenyl)sulfonium hydroxide,
bis(tert-butylphenyl)iodonium hydroxide, phenacylthiophenium
hydroxide and 2-oxopropylthiophenium hydroxide. Examples of the
compound having an onium carboxylate structure include a compound
where the anion moiety of the compound having an onium hydroxide
structure is converted into a carboxylate, such as acetate,
adamantane-1-carboxylate and perfluoroalkyl carboxylate. Examples
of the compound having a trialkylamine structure include
tri(n-butyl)amine and tri(n-octyl)amine. Examples of the aniline
compound include 2,6-diisopropylaniline, N,N-dimethylaniline,
N,N-dibutylaniline and N,N-dihexylaniline. Examples of the
alkylamine derivative having a hydroxyl group and/or an ether bond
include ethanolamine, diethanolamine, triethanolamine and
tris(methoxyethoxyethyl)amine. Examples of the aniline derivative
having a hydroxyl group and/or an ether bond include
N,N-bis(hydroxyethyl)aniline.
[0556] One of these basic compounds is used alone, or two or more
kinds thereof are used in combination.
[0557] The amount of the basic compound used is usually from 0.001
to 10 mass %, preferably from 0.01 to 5 mass %, based on the solid
content of the resist composition.
[0558] The ratio between the acid generator and the basic compound
used in the composition is preferably acid generator/basic compound
(by mol)=from 2.5 to 300. That is, the molar ratio is preferably
2.5 or more in view of sensitivity and resolution and preferably
300 or less from the standpoint of suppressing the reduction in
resolution due to thickening of the resist pattern with aging after
exposure until heat treatment. The acid generator/basic compound
(by mol) is more preferably from 5.0 to 200, still more preferably
from 7.0 to 150.
(F) Surfactant
[0559] The resist composition of the present invention preferably
further contains (F) a surfactant, more preferably any one
fluorine-containing and/or silicon-containing surfactant (a
fluorine-containing surfactant, a silicon-containing surfactant or
a surfactant containing both a fluorine atom and a silicon atom) or
two or more kinds thereof.
[0560] When the resist composition of the present invention
contains the surfactant (F), a resist pattern with good
sensitivity, resolution and adherence as well as less development
defects can be obtained in using an exposure light source of 250 nm
or less, particularly 220 nm or less.
[0561] Examples of the fluorine-containing and/or
silicon-containing surfactant include surfactants described in
JP-A-62-36663, JP-A-61-226746, JP-A-61-226745, JP-A-62-170950,
JP-A-63-34540, JP-A-7-230165, JP-A-8-62834, JP-A-9-54432,
JP-A-9-5988, JP-A-2002-277862 and U.S. Pat. Nos. 5,405,720,
5,360,692, 5,529,881, 5,296,330, 5,436,098, 5,576,143, 5,294,511
and 5,824,451. The following commercially available surfactants
each may also be used as it is.
[0562] Examples of the commercially available surfactant which can
be used include a fluorine-containing or silicon-containing
surfactant such as EFtop EF301 and EF303 (produced by Shin-Akita
Kasei K.K.); Florad FC430, 431 and 4430 (produced by Sumitomo 3M
Inc.); Megaface F171, F173, F176, F189, F113, F110, F177, F120 and
R08 (produced by Dainippon Ink & Chemicals, Inc.); Surflon
S-382, SC101, 102, 103, 104, 105 and 106 (produced by Asahi Glass
Co., Ltd.); Troysol S-366 (produced by Troy Chemical); GF-300 and
GF-150 (produced by Toagosei Chemical Industry Co., Ltd.); Surflon
S-393 (produced by Seimi Chemical Co., Ltd.); Eftop EF121, EF122A,
EF122B, RF122C, EF125M, EF135M, EF351, 352, EF801, EF802 and EF601
(produced by JEMCO Inc.); PF636, PF656, PF6320 and PF6520 (produced
by OMNOVA); and FTX-204D, 208G, 218G, 230G, 204D, 208D, 212D, 218
and 222D (produced by NEOS Co., Ltd.). In addition, polysiloxane
polymer KP-341 (produced by Shin-Etsu Chemical Co., Ltd.) may also
be used as the silicon-containing surfactant.
[0563] Other than those known surfactants, a surfactant using a
polymer having a fluoro-aliphatic group derived from a
fluoro-aliphatic compound which is produced by a telomerization
process (also called a telomer process) or an oligomerization
process (also called an oligomer process), may be used. The
fluoro-aliphatic compound can be synthesized by the method
described in JP-A-2002-90991.
[0564] The polymer having a fluoro-aliphatic group is preferably a
copolymer of a fluoro-aliphatic group-containing monomer with a
(poly(oxyalkylene)) acrylate and/or a (poly(oxyalkylene))
methacrylate, and the copolymer may have an irregular distribution
or may be a block copolymer. Examples of the poly(oxyalkylene)
group include a poly(oxyethylene) group, a poly(oxypropylene) group
and a poly(oxybutylene) group. This group may also be a unit having
alkylenes differing in the chain length within the same chain, such
as block-linked poly(oxyethylene, oxypropylene and oxyethylene) and
block-linked poly(oxyethylene and oxypropylene). Furthermore, the
copolymer of a fluoro-aliphatic group-containing monomer and a
(poly(oxyalkylene)) acrylate (or methacrylate) is not limited only
to a binary copolymer but may also be a ternary or greater
copolymer obtained by simultaneously copolymerizing two or more
different fluoro-aliphatic group-containing monomers or two or more
different (poly(oxyalkylene)) acrylates (or methacrylates).
[0565] Examples thereof include, as the commercially available
surfactant, Megaface F178, F-470, F-473, F-475, F-476 and F-472
(produced by Dainippon Ink & Chemicals, Inc.) and further
include a copolymer of a C.sub.6F.sub.13 group-containing acrylate
(or methacrylate) with a (poly(oxyalkylene)) acrylate (or
methacrylate), and a copolymer of a C.sub.3F.sub.7 group-containing
acrylate (or methacrylate) with a (poly(oxyethylene)) acrylate (or
methacrylate) and a (poly(oxypropylene)) acrylate (or
methacrylate).
[0566] In the present invention, a surfactant other than the
fluorine-containing and/or silicon-containing surfactant may also
be used. Specific examples thereof include a nonionic surfactant
such as polyoxyethylene alkyl ethers (e.g., polyoxyethylene lauryl
ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether,
polyoxyethylene oleyl ether), polyoxyethylene alkylaryl ethers
(e.g., polyoxyethylene octylphenol ether, polyoxyethylene
nonylphenol ether), polyoxyethylene.polyoxypropylene block
copolymers, sorbitan fatty acid esters (e.g., sorbitan monolaurate,
sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate,
sorbitan trioleate, sorbitan tristearate) and polyoxyethylene
sorbitan fatty acid esters (e.g., polyoxyethylene sorbitan
monolaurate, polyoxyethylene sorbitan monopalmitate,
polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan
trioleate, polyoxyethylene sorbitan tristearate).
[0567] One of these surfactants may be used alone, or several
surfactants may be used in combination.
[0568] The amount of the surfactant (F) used is preferably from
0.01 to 10 mass %, more preferably from 0.1 to 5 mass %, based on
the entire amount of the resist composition (excluding the
solvent).
(G) Onium Carboxylate
[0569] The resist composition of the present invention may contain
(G) an onium carboxylate. Examples of the onium carboxylate include
sulfonium carboxylate, iodonium carboxylate and ammonium
carboxylate. In particular, the onium carboxylate (G) is preferably
an iodonium salt or a sulfonium salt. Furthermore, the carboxylate
residue of the onium carboxylate (G) for use in the present
invention preferably contains no aromatic group and no
carbon-carbon double bond. The anion moiety is preferably a linear,
branched, monocyclic or polycyclic alkylcarboxylate anion having a
carbon number of 1 to 30, more preferably an anion of the
carboxylic acid with the alkyl group being partially or entirely
fluorine-substituted. The alkyl chain may contain an oxygen atom.
Thanks to such a construction, the transparency to light of 220 nm
or less is ensured, the sensitivity and resolution are enhanced,
and the iso/dense bias and exposure margin are improved.
[0570] Examples of the anion of the fluorine-substituted carboxylic
acid include anions of fluoroacetic acid, difluoroacetic acid,
trifluoroacetic acid, pentafluoropropionic acid, heptafluorobutyric
acid, nonafluoropentanoic acid, perfluorododecanoic acid,
perfluorotridecanoic acid, perfluorocyclohexanecarboxylic acid and
2,2-bistrifluoromethylpropionic acid.
[0571] These onium carboxylates (G) can be synthesized by reacting
a sulfonium, iodonium or ammonium hydroxide and a carboxylic acid
with silver oxide in an appropriate solvent.
[0572] The content of the onium carboxylate (G) in the composition
is generally from 0.1 to 20 mass %, preferably from 0.5 to 10 mass
%, more preferably from 1 to 7 mass %, based on the entire solid
content of the composition.
(H) Other Additives
[0573] The resist composition of the present invention may further
contain, for example, a dye, a plasticizer, a photosensitizer, a
light absorber, an alkali-soluble resin, a dissolution inhibitor
and a compound for accelerating dissolution in a developer (for
example, a phenol compound having a molecular weight of 1,000 or
less, or a carboxyl group-containing alicyclic or aliphatic
compound), if desired.
[0574] The phenol compound having a molecular weight of 1,000 or
less can be easily synthesized by one skilled in the art with
reference to the methods described, for example, in JP-A-4-122938,
JP-A-2-28531, U.S. Pat. No. 4,916,210 and European Patent
219294.
[0575] Specific examples of the carboxyl group-containing alicyclic
or aliphatic compound include, but are not limited to, a carboxylic
acid derivative having a steroid structure, such as cholic acid,
deoxycholic acid and lithocholic acid, an adamantanecarboxylic acid
derivative, an adamantanedicarboxylic acid, a cyclohexanecarboxylic
acid and a cyclohexanedicarboxylic acid.
EXAMPLES
[0576] The present invention is described below by referring to
Examples, but the present invention should not be construed as
being limited thereto.
Synthesis Example 1
Synthesis of Resin (A1)
[0577] Under a nitrogen stream, 8.4 g of methyl isobutyl ketone was
charged into a three-neck flask and heated at 80.degree. C.
Thereto, a solution obtained by dissolving 9.4 g of
2-(1-adamantyl)propan-2-yl methacrylate, 4.5 g of
3,5-dihydroxy-1-adamantyl methacrylate, 6.1 g of
.beta.-methacryloyloxy-.gamma.-butyrolactone and
azobisisobutyronitrile corresponding to 6 mol % based on the entire
monomer amount, in 75.3 g of methyl isobutyl ketone was added
dropwise over 6 hours. After the completion of dropwise addition,
the reaction was further allowed to proceed at 80.degree. C. for 2
hours. The resulting reaction solution was allowed to cool and then
poured in 720 ml of heptane/80 ml of ethyl acetate, and the powder
precipitated was collected by filtration and dried, as a result,
18.3 g of Resin (A1) was obtained. The weight average molecular
weight of the obtained resin was 7,000 and the dispersity (Mw/Mn)
was 1.80.
Resin (A1):
[0578] ##STR00079## [0579] Weight average molecular eight: 7,000
[0580] Dispersity: 1.80 [0581] Molar compositional ratio:
40/20/40
Synthesis Example 2
Synthesis of Resin (A2)
[0582] Under a nitrogen stream, 8.4 g of methyl isobutyl ketone was
charged into a three-neck flask and heated at 80.degree. C.
Thereto, a solution obtained by dissolving 9.4 g of
2-(1-adamantyl)propan-2-yl methacrylate, 4.5 g of
3,5-dihydroxy-1-adamantyl methacrylate, 6.1 g of
.beta.-methacryloyloxy-.gamma.-butyrolactone and
azobisisobutyronitrile corresponding to 7 mol % based on the entire
monomer amount, in 75.3 g of methyl isobutyl ketone was added
dropwise over 6 hours. After the completion of dropwise addition,
the reaction was further allowed to proceed at 80.degree. C. for 2
hours. The resulting reaction solution was allowed to cool and then
poured in 680 ml of heptane/120 ml of ethyl acetate, and the powder
precipitated was collected by filtration and dried, as a result,
17.5 g of Resin (A2) was obtained. The weight average molecular
weight of the obtained resin was 5,800 and the dispersity (Mw/Mn)
was 1.53.
Resin (A2):
[0583] ##STR00080## [0584] Weight average molecular eight: 5,800
[0585] Dispersity: 1.53 [0586] Molar compositional ratio:
40/20/40
Synthesis Example 3
Synthesis of Resin (A3)
[0587] Under a nitrogen stream, 19.4 g of methyl isobutyl ketone
was charged into a three-neck flask and heated at 80.degree. C.
Thereto, a solution obtained by dissolving 9.4 g of
2-(1-adamantyl)propan-2-yl methacrylate, 4.5 g of
3,5-dihydroxy-1-adamantyl methacrylate, 6.1 g of
.beta.-methacryloyloxy-.gamma.-butyrolactone and
azobisisobutyronitrile corresponding to 12 mol % based on the
entire monomer amount, in 65.3 g of methyl isobutyl ketone was
added dropwise over 8 hours. After the completion of dropwise
addition, the reaction was further allowed to proceed at 80.degree.
C. for 2 hours. The resulting reaction solution was allowed to cool
and then poured in 720 ml of heptane/80 ml of ethyl acetate, and
the powder precipitated was collected by filtration and dried, as a
result, 15.5 g of Resin (A3) was obtained. The weight average
molecular weight of the obtained resin was 2,800 and the dispersity
(Mw/Mn) was 1.26.
Resin (A3):
[0588] ##STR00081## [0589] Weight average molecular eight: 2,800
[0590] Dispersity: 1.26 [0591] Molar compositional ratio:
40/20/40
Synthesis Example 4
Synthesis of Resin (A4)
[0592] Under a nitrogen stream, 8.4 g of methyl isobutyl ketone was
charged into a three-neck flask and heated at 80.degree. C.
Thereto, a solution obtained by dissolving 9.4 g of
2-(1-adamantyl)propan-2-yl methacrylate, 4.5 g of
3,5-dihydroxy-1-adamantyl methacrylate, 6.1 g of
.beta.-methacryloyloxy-.gamma.-butyrolactone and
azobisisobutyronitrile corresponding to 6 mol % based on the entire
monomer amount, in 75.3 g of methyl isobutyl ketone was added
dropwise over 6 hours. After the completion of dropwise addition,
the reaction was further allowed to proceed at 80.degree. C. for 2
hours. The resulting reaction solution was allowed to cool and then
poured in 680 ml of heptane/120 ml of ethyl acetate, and the powder
precipitated was collected by filtration and dried, as a result,
17.6 g of Resin (A4) was obtained. The weight average molecular
weight of the obtained resin was 7,000 and the dispersity (Mw/Mn)
was 1.55.
Resin (A4):
[0593] ##STR00082## [0594] Weight average molecular eight: 7,000
[0595] Dispersity: 1.55 [0596] Molar compositional ratio:
40/20/40
Synthesis Example 5
Synthesis of Resin (A5)
[0597] Under a nitrogen stream, 8.4 g of methyl isobutyl ketone was
charged into a three-neck flask and heated at 80.degree. C.
Thereto, a solution obtained by dissolving 9.4 g of
2-(1-adamantyl)propan-2-yl methacrylate, 4.5 g of
3,5-dihydroxy-1-adamantyl methacrylate, 6.1 g of
.beta.-methacryloyloxy-.gamma.-butyrolactone and
azobisisobutyronitrile corresponding to 7 mol % based on the entire
monomer amount, in 75.3 g of methyl isobutyl ketone was added
dropwise over 6 hours. After the completion of dropwise addition,
the reaction was further allowed to proceed at 80.degree. C. for 2
hours. The resulting reaction solution was allowed to cool and then
poured in 720 ml of heptane/80 ml of ethyl acetate, and the powder
precipitated was collected by filtration and dried, as a result,
18.5 g of Resin (A5) was obtained. The weight average molecular
weight of the obtained resin was 6,000 and the dispersity (Mw/Mn)
was 1.75.
Resin (A5):
[0598] ##STR00083## [0599] Weight average molecular eight: 6,000
[0600] Dispersity: 1.75 [0601] Molar compositional ratio:
40/20/40
Resist Composition (A1):
[0602] A solution having a solid content concentration of 5.8 mass
% obtained by dissolving the components shown below in a mixed
solvent of propylene glycol monomethyl ether acetate/propylene
glycol monomethyl ether (60:40) was filtered through a polyethylene
filter having a pore size of 0.1 .mu.m to prepare Resist
Composition (A1).
[0603] Resin (A1): 1.83 g, triphenylsulfonium nonaflate: 69.6 mg,
diphenylaniline: 8.7 mg, and PF6320 (fluorine-containing surfactant
produced by OMNOVA): 1.7 mg.
Resist Compositions (A2) to (A5):
[0604] Resist Compositions (A2) to (A5) were prepared in the same
manner except for using Resins (A2) to (A5) in place of Resin
(A1).
Comparative Example 1
[0605] An organic antireflection film, ARC29A (produced by Nissan
Chemical Industries, Ltd.), was coated on a 8-inch silicon wafer
and baked at 205.degree. C. for 60 seconds to form an
antireflection film having a thickness of 78 nm, and Resist
Composition (A1) prepared above was coated thereon and baked at
120.degree. C. for 60 seconds to form a resist film having a
thickness of 150 nm. The obtained wafer was subjected to pattern
exposure using an ArF excimer laser scanner (NA: 0.75). Thereafter,
the resist film was heated at 120.degree. C. for 60 seconds,
developed with an aqueous tetramethylammonium hydroxide solution
(2.38 mass %) (positive tone developer) for 30 seconds (positive
tone development), and rinsed with pure water to obtain a pattern
having a pitch of 600 nm and a line width of 450 nm. Furthermore,
the resist film was developed with butyl acetate (negative tone
developer) for 30 seconds (negative tone development) and rinsed
with 1-hexanol (rinsing solution for negative tone development) for
30 seconds, and thereafter, the wafer was rotated at a rotation
number of 3,000 rpm for 30 seconds to obtain a 150-nm (1:1)
line-and-space resist pattern.
Examples 1 to 4
[0606] In the same manner as in Comparative Example 1, 150-nm (1:1)
resist patterns were obtained using Resist Compositions (A2) to
(A5), respectively.
Evaluation of Line Edge Roughness (LER):
[0607] The 150-nm (1:1) line-and-space resist patterns obtained in
Comparative Example 1 and Examples 1 to 4 were observed by a
scanning microscope (S9260, manufactured by Hitachi Ltd.). With
respect to the range of 2 .mu.m edge in the longitudinal direction
of the 150-nm line pattern, the distance from the reference line
where the edge should be present was measured at 50 points and
after determining the standard deviation, 3.sigma. (unit: nm) was
calculated. A smaller value indicates better performance.
[0608] The results are shown in Table 1.
TABLE-US-00001 TABLE 1 Resist Molecular LER Composition Resin
Weight Dispersity (nm) Comparative A1 A1 7000 1.80 9.5 Example 1
Example 1 A2 A2 5800 1.53 6.8 Example 2 A3 A3 2800 1.26 5.2 Example
3 A4 A4 7000 1.55 7.0 Example 4 A5 A5 6000 1.75 7.1
Example 5
[0609] An organic antireflection film, ARC29A (produced by Nissan
Chemical Industries, Ltd.), was coated on a 8-inch silicon wafer
and baked at 205.degree. C. for 60 seconds to form an
antireflection film having a thickness of 78 nm, and Resist
Composition (A2) prepared above was coated thereon and baked at
120.degree. C. for 60 seconds to form a resist film having a
thickness of 150 nm. The obtained wafer was subjected to pattern
exposure using an ArF excimer laser scanner (NA: 0.75). Thereafter,
the resist film was heated at 120.degree. C. for 60 seconds,
developed with an aqueous tetramethylammonium hydroxide solution
(2.38 mass %) (positive tone developer) for 30 seconds (positive
tone development), and rinsed with pure water to obtain a pattern
having a pitch of 600 nm and a line width of 450 .mu.m.
Furthermore, the resist film was developed with ethyl acetate
(negative tone developer) for 30 seconds (negative tone
development) and rinsed with 1-hexanol (rinsing solution for
negative tone development) for 30 seconds, and thereafter, the
wafer was rotated at a rotation number of 3,000 rpm for 30 seconds
to obtain a 150-nm (1:1) line-and-space resist pattern.
Examples 6 to 18
[0610] In the same manner as in Example 5, 150-nm (1:1) resist
patterns were obtained by using Resist Composition (A2) and
combining the negative tone developer and the rinsing solution for
negative tone development as shown in Table 2.
Evaluation of Dimensional Uniformity:
[0611] The 150-nm (1:1) line-and-space resist patterns obtained in
Examples 1 and 5 to 18 each was measured for the dimension at 50
portions at intervals of 2 nm by using a scanning microscope
(S9260, manufactured by Hitachi Ltd.). The standard deviation of 50
portions was determined, and 3.sigma. (unit: nm) was calculated. A
smaller value indicates better performance. The results are shown
in Table 2.
TABLE-US-00002 TABLE 2 Rinsing Solution for Dimensional Negative
Tone Uniformity Negative Tone Developer Development (nm) Example 1
butyl acetate 1-hexanol 3.1 Example 5 ethyl acetate 1-hexanol 8.4
Example 6 isoamyl acetate 1-hexanol 3.1 Example 7 methyl isobutyl
ketone 1-hexanol 3.5 Example 8 2-hexanone 1-hexanol 2.7 Example 9
methyl ethyl ketone 1-hexanol 9.6 Example 10 dipropyl ether
1-hexanol 11.6 Example 11 dibutyl ether 1-hexanol 4.2 Example 12
butyl acetate/2-hexanone 1-hexanol 3.5 (80/20) Example 13 isoamyl
acetate/dibutyl 1-hexanol 3.8 ether (70/30) Example 14 isoamyl
acetate 1-heptanol 8.8 Example 15 isoamyl acetate 2-heptanol 3.3
Example 16 isoamyl acetate decane 4.3 Example 17 isoamyl acetate
dodecane 9.2 Example 18 isoamyl acetate 1-heptanol/decane 3.7
(50/50)
[0612] The vapor pressure and boiling point of each of the solvent
for negative tone developer and the solvent for rinsing solution
for negative tone development used in Examples 1 and 5 to 18 are
shown in Table 3.
TABLE-US-00003 TABLE 3 Vapor Pressure Solvent Name (20.degree. C.)
Boiling Point butyl acetate 1.2 kPa 126.degree. C. ethyl acetate 10
kPa 77.degree. C. isoamyl acetate 0.53 kPa 142.degree. C. methyl
isobutyl ketone 2.1 kPa 117-118.degree. C. 2-hexanone 0.36 kPa
126-128.degree. C. methyl ethyl ketone 10.5 kPa 80.degree. C.
dipropyl ether 8.3 kPa 88-90.degree. C. dibutyl ether 0.64 kPa
142.degree. C. 1-hexanol 0.13 kPa 157.degree. C. 1-heptanol 0.015
kPa 175.degree. C. 2-heptanol 0.13 kPa 150-160.degree. C. decane
0.17 kPa 174.2.degree. C. dodecane 0.040 kPa 216.2.degree. C.
Comparative Example 2
[0613] An organic antireflection film, ARC29A (produced by Nissan
Chemical Industries, Ltd.), was coated on a 8-inch silicon wafer
and baked at 205.degree. C. for 60 seconds to form an
antireflection film having a thickness of 78 nm, and Resist
Composition (A1) prepared above was coated thereon and baked at
120.degree. C. for 60 seconds to form a resist film having a
thickness of 150 nm. The obtained wafer was subjected to pattern
exposure using an ArF excimer laser scanner (NA: 0.75).
Subsequently, the resist film was developed with butyl acetate
(negative tone developer) for 30 seconds (negative tone
development) and rinsed with 1-hexanol (rinsing solution for
negative tone development) for 30 seconds, and thereafter, the
wafer was rotated at a rotation number of 3,000 rpm for 30 seconds
to obtain a pattern having a pitch of 400 nm and a line width of
200 nm.
Examples 20 to 29
[0614] In the same manner as in Comparative Example 2, patterns
having a pitch 400 nm and a line width of 200 nm were obtained
using Resist Compositions (A2) to (A5) and (B1) to (B6),
respectively. The formulations of Resist Compositions (A2) to (A5)
are as described above, and the formulations of Resist Compositions
(B1) to (B6) were prepared in the same manner as Resist Composition
(A1) except for changing the formulation to the formulations shown
in Table 5 below.
Evaluation of Line Edge Roughness (LER):
[0615] The patterns having a pitch of 400 nm and a line width of
200 nm obtained in Comparative Example 2 and Examples 20 to 29 were
observed by a scanning microscope (S9260, manufactured by Hitachi
Ltd.). With respect to the range of 2 .mu.m edge in the
longitudinal direction of the 200-nm line pattern, the distance
from the reference line where the edge should be present was
measured at 50 points and after determining the standard deviation,
3.sigma. (unit: nm) was calculated. A smaller value indicates
better performance. The results are shown in Tables 4 and 5.
TABLE-US-00004 TABLE 4 Resist Molecular LER Composition Resin
Weight Dispersity (nm) Comparative A1 A1 7000 1.80 8.9 Example 2
Example 20 A2 A2 5800 1.53 6.3 Example 21 A3 A3 2800 1.26 5.3
Example 22 A4 A4 7000 1.55 7.2 Example 23 A5 A5 6000 1.75 7.4
TABLE-US-00005 TABLE 5 Acid Basic Solvent Resist Resin Generator
Compound Surfactant (mass LER Example Composition (10 g) (g) (g)
(0.02 g) ratio) (nm) 24 B1 A6 PAG-A PEA (0.05) W-5 A1/B1 6.0 (0.50)
(60/40) 25 B2 A7 PAG-E DIA (0.05) W-2 A1/B2 5.8 (0.40) (40/60) 26
B3 A8 PAG-B TPA (0.06) W-6 A2/B3 6.3 (0.80) (95/5) 27 B4 A9 PAG-C
PBI (0.07) W-1 A2/B1 6.1 (0.60) (50/50) 28 B5 A7 PAG-F DIA (0.10)
W-4 A2/B2 6.5 (0.20) (40/60) 29 B6 A9 PAG-D TOA W-3 A1/B3 6.2
(0.90) (0.08) (90/10)
[0616] The abbreviations used in Examples indicate those set forth
as specific examples above or the followings.
TABLE-US-00006 TABLE 6 Compositional No. Monomer (1) Monomer (2)
Monomer (3) Ratio (by mol) Mw Mw/Mn A6 ##STR00084## ##STR00085##
##STR00086## 30/30/40 5000 1.4 A7 ##STR00087## ##STR00088##
##STR00089## 50/20/30 5500 1.5 A8 ##STR00090## ##STR00091##
##STR00092## 50/10/40 4800 1.5 A9 ##STR00093## ##STR00094##
##STR00095## 40/20/40 5300 1.6
##STR00096##
DIA: 2,6-diisopropylaniline TPA: tripentylamine
PEA: N-phenyldiethanolamine
[0617] TOA: trioctylamine PBI: 2-phenylbenzimidazole W-1: Megaface
F176 (produced by Dainippon Ink & Chemicals, Inc.)
(fluorine-containing) W-2: Megaface R08 (produced by Dainippon Ink
& Chemicals, Inc.) (fluorine and silicon-containing) W-3:
Polysiloxane Polymer KP-341 (produced by Shin-Etsu Chemical Co.,
Ltd.) (silicon-containing) W-4: Troysol S-366 (produced by Troy
Chemical) W-5: PF656 (produced by OMNOVA, fluorine-containing) W-6:
PF6320 (produced by OMNOVA, fluorine-containing) A1: propylene
glycol monomethyl ether acetate A2: cyclohexanone B1: propylene
glycol monomethyl ether B2: ethyl lactate B3:
.gamma.-butyrolactone
[0618] As apparent from these Examples, thanks to the combination
of resist composition, negative tone developer and rinsing solution
for negative tone development of the present invention, the line
edge roughness is reduced and furthermore, the dimensional
uniformity is high.
INDUSTRIAL APPLICABILITY
[0619] By the pattern forming method and the resist composition of
the present invention, a pattern with reduced line edge roughness
and high dimensional uniformity is obtained. In particular, a
highly practical negative tone development technique and a double
development technique using the same are provided. These techniques
enables finer patterning under the same light source as that in
conventional technology. The pattern forming method of the present
invention is suitably used in the process of producing a
semiconductor such as IC, in the production of a circuit board for
liquid crystal, thermal head and the like, and in the lithography
process of other photofabrications.
[0620] While the invention has been described in detail and with
reference to specific embodiments thereof, it will be apparent to
one skilled in the art that various changes and modifications can
be made therein without departing from the spirit and scope
thereof.
* * * * *