U.S. patent application number 10/742878 was filed with the patent office on 2004-07-15 for positive photoresist composition.
This patent application is currently assigned to TOKYO OHKA KOGYO CO., LTD.. Invention is credited to Doi, Kousuke, Kurihara, Masaki, Maruyama, Kenji, Niikura, Satoshi, Suzuki, Takako.
Application Number | 20040137359 10/742878 |
Document ID | / |
Family ID | 18876869 |
Filed Date | 2004-07-15 |
United States Patent
Application |
20040137359 |
Kind Code |
A1 |
Kurihara, Masaki ; et
al. |
July 15, 2004 |
Positive photoresist composition
Abstract
A composition includes (A) an alkali-soluble resin, (B) a
quinonediazide ester of a compound represented by the following
formula: 1 and (C) a compound represented by the following formula:
2 This composition is a positive photoresist composition that is
excellent in sensitivity and definition and causes less shrink.
Inventors: |
Kurihara, Masaki; (Kanagawa,
JP) ; Suzuki, Takako; (Kanagawa, JP) ;
Maruyama, Kenji; (Kanagawa, JP) ; Niikura,
Satoshi; (Kanagawa, JP) ; Doi, Kousuke;
(Kanagawa, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
TOKYO OHKA KOGYO CO., LTD.
|
Family ID: |
18876869 |
Appl. No.: |
10/742878 |
Filed: |
December 23, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10742878 |
Dec 23, 2003 |
|
|
|
10035137 |
Jan 4, 2002 |
|
|
|
Current U.S.
Class: |
430/191 ;
430/192; 430/193; 430/326 |
Current CPC
Class: |
G03F 7/022 20130101;
G03F 7/0226 20130101 |
Class at
Publication: |
430/191 ;
430/192; 430/193; 430/326 |
International
Class: |
G03F 007/023 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 17, 2001 |
JP |
2001-9372 |
Claims
What is claimed is:
1. A positive photoresist composition comprising; (A) an
alkali-soluble resin; (B) a photosensitizer comprising a
quinonediazide ester between a naphthoquinonediazidosulfonic acid
compound and a compound represented by following Formula (I): 29
wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6,
R.sup.7 and R.sup.8 are each independently a hydrogen atom or an
alkyl group having from 1 to 3 carbon atoms, and (C) a sensitizer
comprising at least one of compounds represented by following
Formula (III): 30 wherein x is 0 or 1.
2. The positive photoresist composition according to claim 1,
wherein the compound represented by Formula (I) is a compound
represented by the following formula: 31
3. The positive photoresist composition according to claim 1,
wherein the compound represented by Formula (III) is a compound
represented by the following formula: 32
4. The positive photoresist composition according to claim 1,
wherein the compound represented by Formula (III) is a compound
represented by the following formula: 33
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of application Ser. No. 10/035,137
filed Jan. 4, 2002; the disclosure of which is incorporated herein
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a positive photoresist
composition that is excellent in sensitivity and definition and is
advantageously used for patterning a resist with less shrink.
[0004] 2. Description of the Related Art
[0005] In photolithography processes using i-line (365 nm), demands
have been made on photoresist materials that can form an ultrafine
resist pattern of not more than half a micrometer, particularly of
not more than 0.35 .mu.m. As such photoresist materials, positive
photoresist compositions each comprising an alkali-soluble novolak
resin and a non-benzophenone naphthoquinonediazido-group-containing
compound (a photosensitizer) have been proposed.
[0006] For example, Japanese Patent Laid-Open No. 6-167805 mentions
that a positive photoresist material using an esterified product
between a tetra- to hepta-nuclear linear polyphenol compound and a
naphthoquinonediazidosulfonic acid compound is a high-definition
material for use in photolithography processes using i-line.
[0007] Photolithography processes using short-wavelength light
sources such as KrF excimer laser (248 nm) and ArF excimer laser
(193 nm) are suitable for the formation of resist patterns of not
more than 0.35 .mu.m. However, manufacturing lines using these
light sources require a large amount of spending on new plants and
equipment, and such spending is nearly unrecoverable.
[0008] Under these circumstances, strong demands have been made on
the use of the photolithography processes using i-line (365 nm)
from now on, which are widely used at present, and techniques of
ultrafine processing of resist patterns of not more than 0.35 .mu.m
using photoresist materials for i-line irradiation have been
examined.
[0009] However, it has been believed that by using a light source
having a wavelength greater than the size of the resulting resist
pattern, a resist pattern having satisfactory sensitivity,
definition, focal depth range properties and other properties
cannot be obtained. For example, this type of resist patterns
exhibits "shrink", the phenomenon that the resist pattern shrinks
in a length direction upon shifting of the focus on the order of
submicron from an optimal position during exposure. The shrink is
often observed in both edges of a resist pattern comprising regular
line-and-space (L&S) traces or in an isolation pattern or
irregular resist pattern. Accordingly, the resulting pattern in,
for example, a logical IC having complicated traces cannot be
obtained in a good yield.
SUMMARY OF THE INVENTION
[0010] Accordingly, an object of the present invention is to solve
the above problems and to provide a positive photoresist
composition that is excellent in sensitivity and definition and can
form a resist pattern with less shrink upon shifting of the focus
even in the formation of an ultrafine resist pattern of not more
than 0.35 .mu.m.
[0011] After intensive investigations to achieve the above objects,
the present inventors have found that a positive photoresist
composition containing an alkali-soluble resin, a specific
quinonediazide ester (a photosensitizer) and a specific compound (a
sensitizer) is excellent in sensitivity and definition and causes
less shrink. The present invention has been accomplished based on
these findings.
[0012] Specifically, the present invention provides a positive
photoresist composition including (A) an alkali-soluble resin, (B)
a photosensitizer including a quinonediazide ester between a
naphthoquinonediazidosulfonic acid compound and at least one of a
compound represented by following Formula (I): 3
[0013] wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5,
R.sup.6, R.sup.7 and R.sup.8 are each independently a hydrogen atom
or an alkyl group having from 1 to 3 carbon atoms, and a compound
represented by following Formula (II): 4
[0014] wherein R.sup.9, R.sup.10, R.sup.11, R.sup.12, R.sup.13,
R.sup.14, R.sup.15, R.sup.16, R.sup.17 and R.sup.18 are each
independently a hydrogen atom, an alkyl group having from 1 to 3
carbon atoms or a cyclohexyl group, and (C) a sensitizer including
at least one of a compound represented by following Formula (III):
5
[0015] wherein x is 0 or 1.
[0016] The compound represented by Formula (I) in the positive
photoresist composition is preferably a compound represented by the
following formula: 6
[0017] The compound represented by Formula (II) is preferably a
compound represented by the following formula: 7
[0018] The compound represented by Formula (III) is preferably a
compound represented by the following formula: 8
[0019] Alternatively, the compound represented by Formula (III) is
preferably a compound represented by the following formula: 9
[0020] In this connection, one type of the compounds represented by
Formula (III) is disclosed as a sensitizer in Japanese Patent No.
2629990. However, such conventional technologies fail to disclose
the combination use of the compound represented by Formula (III)
with the compound represented by Formula (I) and/or the compound
represented by Formula (II).
[0021] The present invention can therefore provide a positive
photoresist composition that is excellent in sensitivity and
definition and can form a resist pattern with less shrink upon
shifting of the focus even in the formation of an ultrafine resist
pattern of not more than 0.35 .mu.m.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention will be illustrated in detail
below.
[0023] Ingredient (A): Alkali-Soluble Resin
[0024] Alkali-soluble resins for use as the ingredient (A) are not
specifically limited and can be optionally chosen from those
generally used as film-forming substances in positive photoresist
compositions. Of these resins, condensates of aromatic hydroxy
compounds and aldehydes or ketones, polyhydroxystyrenes and
derivatives thereof are preferable.
[0025] Such aromatic hydroxy compounds include, but are not limited
to, phenol, m-cresol, p-cresol, o-cresol, and other cresols;
2,3-xylenol, 2,5-xylenol, 3,5-xylenol, 3,4-xylenol, and other
xylenols ; m-ethylphenol, p-ethylphenol, o-ethylphenol,
2,3,5-trimethylphenol, 2,3,5-triethylphenol, 4-tert-butylphenol,
3-tert-butylphenol, 2-tert-butylphenol,
2-tert-butyl-4-methylphenol, 2-tert-butyl-5-methylphe- nol, and
other alkyl-substituted phenols; p-methoxyphenol, m-methoxyphenol,
p-ethoxyphenol, m-ethoxyphenol, p-propoxyphenol, m-propoxyphenol,
and other alkoxy-substituted phenols; o-isopropenylphenol,
p-isopropenylphenol, 2-methyl-4-isopropenylphenol,
2-ethyl-4-isopropenylphenol, and other isopropenyl-substituted
phenols; phenylphenol, and other aryl-substituted phenols;
4,4'-dihydroxybiphenyl, bisphenol A, resorcinol, hydroquinone,
pyrogallol, and other polyhydroxyphenols. Each of these compounds
can be used alone or in combination.
[0026] The aldehydes include, but are not limited to, formaldehyde,
paraformaldehyde, trioxane, acetaldehyde, propionaldehyde,
butylaldehyde, trimethylacetaldehyde, acrolein (acrylaldehyde),
crotonaldehyde, cyclohexanealdehyde, furfural, furylacrolein,
benzaldehyde, terephthalaldehyde, phenylacetaldehyde,
.alpha.-phenylpropylaldehyde, .beta.-phenylpropylaldehyde,
o-hydroxybenzaldehyde, m-hydroxybenzaldehyde,
p-hydroxybenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde,
p-methylbenzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde,
p-chlorobenzaldehyde, and cinnamaldehyde. Each of these aldehydes
can be used alone or in combination. Of these aldehydes,
formaldehyde is desirable for its availability. The combination use
of a hydroxybenzaldehyde and formaldehyde is specifically preferred
in order to improve heat resistance.
[0027] The ketones include, for example, acetone, methyl ethyl
ketone, diethyl ketone, and diphenyl ketone. Each of these ketones
may be used alone or in combination. Further, an appropriate
combination of an aldehyde and a ketone can be employed.
[0028] The condensate of an aromatic hydroxy compound and an
aldehyde or a ketone can be prepared in the presence of an acidic
catalyst according to a known technique. Such acidic catalysts
include, but are not limited to, hydrochloric acid, sulfuric acid,
formic acid, oxalic acid, and p-toluenesulfonic acid.
[0029] The polyhydroxystyrenes and derivatives thereof include, but
are not limited to, vinylphenol homopolymers, and copolymers of
vinylphenol and a copolymerizable comonomer. Such comonomers
include, for example, acrylic acid derivatives, acrylonitrile,
methacrylic acid derivatives, methacrylonitrile, styrene,
.alpha.-methylstyrene, p-methylstyrene, o-methylstyrene,
p-methoxystyrene, p-chlorostyrene, and other styrene
derivatives.
[0030] Of these alkali-soluble resins for use in the present
invention as the ingredient (A), preferred resins are
alkali-soluble novolak resins each having a weight average
molecular weight (Mw) of from 2000 to 20000, and typically from
3000 to 12000. These alkali-soluble resins preferably have a
molecular weight dispersion (Mw/Mn) of from 2 to 5. Among them,
alkali-soluble novolak resins obtained by a condensation reaction
of m-cresol and p-cresol with formaldehyde, and alkali-soluble
novolak resins obtained by a condensation reaction of m-cresol,
p-cresol and 2,3,5-trimethylphenol with formaldehyde are preferred
to yield positive photoresist compositions having high sensitivity
and wide exposure margin.
[0031] Ingredient (B): Photosensitizer
[0032] According to the present invention, an ester (hereinafter
referred to as "quinonediazide ester") of a
napthoquinonediazidosulfonic acid compound with at least one of the
compounds represented by Formulae (I) and (II) is used as the
ingredient (B) (photosensitizer). By this configuration, the
resulting positive photoresist composition has excellent
definition.
[0033] The quinonediazide ester of the compound represented by
Formula (I) has an average esterification rate of preferably from
25% to 90% and more preferably from 45% to 75%. If the average
esterification rate is less than 25%, the resulting photoresist
composition may exhibit deteriorated film residual rate and
definition, and in contrast, if it exceeds 90%, the photoresist
composition may exhibit deteriorated sensitivity and increased
scum.
[0034] The quinonediazide ester of the compound represented by
Formula (II) has an average esterification rate of preferably from
20% to 90% and more preferably from 30% to 80%. If the average
esterification rate is less than 20%, the resulting photoresist
composition may exhibit deteriorated film residual rate and
definition, and in contrast, if it exceeds 90%, the photoresist
composition may exhibit deteriorated sensitivity and increased
scum.
[0035] Among the compounds represented by Formula (I) for use in
the ingredient (B) (photosensitizer), typically preferred is a
compound represented by the following formula: 10
[0036] By using this compound, the resulting positive photoresist
composition has further improved sensitivity and definition and
causes less shrink.
[0037] Among the compounds represented by Formula (II) for use in
the ingredient (B) (photosensitizer), typically preferred is a
compound represented by the following formula: 11
[0038] By using this compound, the resulting positive photoresist
composition has further improved sensitivity and definition and
causes less shrink.
[0039] The positive photoresist composition of the present
invention may further comprise additional quinonediazide esters as
the ingredient (B) according to necessity, in addition to the
quinonediazide esters of the compounds represented by Formulae (I)
and (II). Such quinonediazide esters include, but are not limited
to, quinonediazide esters of polyphenol compounds represented by
following Formula (IV): 12
[0040] wherein R.sup.19 to R.sup.26 are each independently a
hydrogen atom, a halogen atom, an alkyl group having from 1 to 6
carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, or a
cycloalkyl group; R.sup.27 to R.sup.29 are each independently a
hydrogen atom or an alkyl group having from 1 to 6 carbon atoms; Q
is a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms,
or Q is combined with R.sup.27 to form a cyclic ring having from 3
to 6 carbon atoms, or a residue represented by the following
formula: 13
[0041] wherein R.sup.30 and R.sup.31 are each independently a
hydrogen atom, a halogen atom, an alkyl group having from 1 to 6
carbon atoms, an alkoxy group having from 1 to 6 carbon atoms, or a
cycloalkyl group; and c is an integer of from 1 to 3; a and b are
each an integer of from 1 to 3; d is an integer of from 0 to 3; and
n is an integer of from 0 to 3. Such polyphenol compounds include,
for example, linear trinuclear compounds, linear tetranuclear
compounds, linear pentanuclear compounds, and trisphenol polyphenol
compounds, other than the compounds represented by Formulae (I) and
(II).
[0042] The amount of these additional quinonediazide esters, if
any, is preferably less than or equal to 75% by weight, and more
preferably less than or equal to 50% by weight based on the weight
of the ingredient (B). If the amount of the additional
quinonediazide esters exceeds 75% by weight, the resulting positive
photoresist composition may have deteriorated definition.
[0043] The content of the ingredient (B) in the positive
photoresist composition of the present invention is preferably from
20% to 60% by weight, and more preferably from 30% to 50% by weight
relative to the total weight of the alkali-soluble resin ingredient
(A) and the sensitizer (intensifier) ingredient (C) described
below. If the content of the ingredient (B) is less than 20% by
weight, images in exact accordance with patterns may not be
obtained, and transferring property may be deteriorated. In
contrast, if the content exceeds 60% by weight, sensitivity and
uniformity of the resulting resist film tend to be deteriorated to
thereby deteriorate definition.
[0044] Ingredient (C): Sensitizer
[0045] the sensitizer (intensifier) for use in the present
invention is an alkali-soluble low molecular weight compound having
a molecular weight of less than or equal to about 1000 and having a
phenolic hydroxyl group.
[0046] According to the present invention, the specific compound
represented by Formula (III) as the sensitizer (C) is used in
combination with the specific quinonediazide esters. By this
configuration, the resulting positive photoresist composition has
high definition, causes less shrink and is therefore suitable in
the fields of the formation of complicated circuit traces such as
in logical ICs.
[0047] Among the compounds represented by Formula (E) for use as
the ingredient (C), typically preferred is a compound represented
by the following formula: 14
[0048] By using this compound, the resulting positive photoresist
composition has further improved sensitivity and definition and
causes less shrink.
[0049] Alternatively, the compound represented by Formula (III) is
preferably a compound represented by the following formula: 15
[0050] By using this compound, the resulting positive photoresist
composition has further improved sensitivity and definition and
causes less shrink.
[0051] The positive photoresist composition may further comprise
additional alkali-soluble low molecular weight compounds each
having a phenolic hydroxyl group as the ingredient (C), in addition
to the compounds represented by Formula (III).
[0052] Such low molecular weight compounds include, for example,
the polyphenol compounds represented by Formula (IV), such as
2,6-bis(2,5-dimethyl-4-hydroxyphenylmethyl)-4-methylphenol,
bis(4-hydroxy-2,3,5-trimethylphenyl)-2-hydroxyphenylmethane,
1,4-bis[1-(3,5-dimethyl-4-hydroxyphenyl)isopropyl]benzene,
2,4-bis(3,5-dimethyl-4-hydroxyphenylmethyl)-6-methylphenol,
bis(4-hydroxy-3,5-dimethylphenyl)-2-hydroxyphenylmethane,
bis(4-hydroxy-2,5-dimethylphenyl)-2-hydroxyphenylmethane,
bis(4-hydroxy-3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane,
1-[1-(4-hydroxyphenyl)isopropyl]-4-[1,1-bis(4-hydroxyphenyl)ethyl]benzene-
,
1-[1-(3-methyl-4-hydroxyphenyl)isopropyl]-4-[1,1-bis(3-methyl-4-hydroxyp-
henyl)ethyl]benzene,
2,6-bis[1-(2,4-dihydroxyphenyl)isopropyl]-4-methylphe- nol,
4,6-bis[1-(4-hydroxyphenyl)isopropyl]resorcin,
4,6-bis(3,5-dimethoxy-4-hydroxyphenylmethyl)pyrogallol,
4,6-bis(3,5-dimethyl-4-hydroxyphenylmethyl)pyrogallol,
2,6-bis(3-methyl-4,6-dihydroxyphenylmethyl)-4-methylphenol,
2,6-bis(2,3,4-trihydroxyphenylmethyl)-4-methylphenol, and
1,1-bis(4-hydroxyphenyl)cyclohexane.
[0053] The content of these additional alkali-soluble low molecular
weight compounds each having a phenolic hydroxyl group, if any, is
preferably less than or equal to 75% by weight and more preferably
less than or equal to 50% by weight based on the total weight of
the ingredient (C). If the content exceeds 75% by weight, the
formation of shrink may not effectively be suppressed.
[0054] The amount of the ingredient (C) is preferably from 20% to
50% by weight and more preferably from 30% to 40% by weight,
relative to the weight of the ingredient (A) alkali-soluble
resin.
[0055] In addition to the above specified ingredients, where
necessary, the positive photoresist composition of the present
invention may further comprise any of compatible additives
including, for example, ultraviolet absorbents for inhibition of
halation and surfactants for prevention of striation within ranges
not adversely affecting the objects of the invention. Such
ultraviolet absorbents include, for example,
2,2'4,4'-tetrahydroxybenzophenone,
4-dimethylamino-2',4'-dihydroxybenzoph- enone,
5-amino-3-methyl-1-phenyl-4-(4-hydroxyphenylazo)pyrazole,
4-dimethylamino-4'-hydroxyazobenzene,
4-diethylamino-4'-ethoxyazobenzene, 4-diethylaminoazobenzene and
curcumin. The surfactants include, but are not limited to, Fluorad
FC-430 and FC-431 (trade names, available from
Fluorochemical-Sumitomo 3M Co.), EFTOP EF122A, EF122B, EF122C and
EF126 (trade names, available from Tohkem Products Corporation) and
other fluorine-containing surfactants.
[0056] The positive photoresist composition of the present
invention is preferably used as a solution prepared by dissolving
each of the ingredients (A), (B) and (C) and other additional
ingredients in an appropriate solvent. Such solvents include those
conventionally used in positive photoresist compositions, such as
acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone,
2-heptanone, and other ketones; ethylene glycol, propylene glycol,
diethylene glycol, ethylene glycol monoacetate, propylene glycol
monoacetate, diethylene glycol monoacetate, or monomethyl ethers,
monoethyl ethers, monopropyl ethers, monobutyl ethers or monophenyl
ethers thereof, and other polyhydric alcohols and derivatives
thereof; dioxane and other cyclic ethers; and ethyl lactate, methyl
acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl
pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, and
other esters. Each of these solvents can be used alone or in
combination. Of these solvents, typically preferred solvents are
acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone,
2-heptanone, and other ketones; and ethyl lactate, methyl acetate,
ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate,
methyl methoxypropionate, ethyl ethoxypropionate, and other
esters.
[0057] Practically, the positive photoresist composition of the
present invention may preferably be used, for example, in the
following manner: Each of the ingredients (A), (B) and (C) and
other ingredients added according to necessity is dissolved in an
appropriate solvent as mentioned above to yield a coating solution;
the coating solution is then applied, using a spinner or the like,
onto a substrate such as a silicon wafer or a substrate carrying an
anti-reflection coating formed thereon, and is then dried to form a
photosensitive layer; next, the photosensitive layer is irradiated
with and is exposed to light through a desired mask pattern; and
the exposed portions of the film are then dissolved and removed by
dipping the substrate in a developer solution, for example, an
alkaline aqueous solution such as a 1% to 10% by weight
tetramethylammonium hydroxide (TMAH) aqueous solution, thus forming
an image being in exact accordance with the mask pattern.
EXAMPLES
[0058] The present invention will be further illustrated in detail
with reference to several examples and comparative examples below
which are not intended to limit the scope of the invention. The
properties of the resulting positive photoresist compositions were
evaluated by the following methods, and the results are shown in
Table 2.
[0059] (1) Sensitivity
[0060] A sample was applied onto a silicon wafer using a spinner,
and was dried on a hot plate at 90.degree. C. for 90 sec. to form a
resist film 1.0 .mu.m thick. The resist film was then irradiated
with light through a mask (reticle) corresponding to a 0.35-.mu.m
resist pattern with a line-and-space (L&S) width of 1:1 for an
increasing period from 0.1 sec. at intervals of 0.01 sec. using a
reducing-type projection aligner NSR-2005i10D (available from Nikon
Corporation, Japan; NA=0.57). The film was then post-exposure baked
(PEB) at 110.degree. C. for 90 sec.; was subjected to developing in
a 2.38% by weight tetramethylammonium hydroxide aqueous solution at
23.degree. C. for 60 sec., was rinsed with water for 30 sec., and
was dried. In this procedure, the sensitivity was defined as the
exposure time period (Eop) in milliseconds (ms) to exactly
reproduce a 0.35-.mu.m mask pattern with a line-and-space (L&S)
width of 1:1.
[0061] (2) Definition
[0062] The definition was defined as the critical definition at an
exposure to reproduce a 0.35-.mu.m mask pattern.
[0063] (3) Shrink Evaluation
[0064] A sample was applied onto a silicon wafer using a spinner
and was dried on a hot plate at 90.degree. C. for 90 sec. to form a
resist film 1.0-.mu.m thick. The resist film was then irradiated
with light through a mask (reticle) corresponding to five parallel
resist traces 0.35-.mu.m wide and 1.0-.mu.m long with a
line-and-space (L&S) width of 1:1 for an increasing period from
0.1 sec. at intervals of 0.01 sec. using a reducing-type projection
aligner NSR-2005i10D (available from Nikon Corporation, Japan;
NA=0.57).
[0065] In this procedure, the resist film was irradiated at the
optimum exposure time period (Eop) under the condition that the
focus was shifted 1.0 .mu.m from the optimum position of the focus
toward the minus side (the upper side of the substrate).
[0066] The film was then post-exposure baked (PEB) at 110.degree.
C. for 90 sec.; was subjected to developing in a 2.38% by weight
tetramethylammonium hydroxide aqueous solution at 23.degree. C. for
60 sec., was rinsed with water for 30 sec., and was dried. In this
procedure, the shrink was evaluated in accordance with the
following criteria by taking the lengths in a longitudinal
direction of the two resist traces at both ends of the five
parallel resist traces as an index.
[0067] Criteria on Shrink Evaluation
[0068] Excellent: The lengths of the resulting traces were equal to
or more than 0.9 .mu.m and less than or equal to 1.0 .mu.m,
indicating that almost no shrink occurred.
[0069] Good: The lengths of the resulting traces were equal to or
more than 0.8 .mu.m and less than 0.9 .mu.m, indicating that some
shrink occurred.
[0070] Fair: The lengths of the resulting traces were equal to or
more than 0.7 .mu.m and less than 0.8 .mu.m.
[0071] Failure: The lengths of the resulting traces were less than
0.7 .mu.m.
Example 1
[0072] Ingredient (A): An alkali-soluble resin comprising 50 parts
by weight of a novolak resin (a1) and 50 parts by weight of a
novolak resin (a2). The novolak resin (a1) had a weight average
molecular weight (Mw) in terms of polystyrene of 5000 and a
molecular weight distribution (Mw/Mn) of 3.0 and was prepared from
m-cresol/p-cresol/2,3,5-trimethylphe- nol=35/40/25 (by mole of
charged material) using formaldehyde as a condensing agent. The
novolak resin (a2) had a weight average molecular weight (Mw) in
terms of polystyrene of 5000 and a molecular weight distribution
(Mw/Mn) of 3.0 and was prepared from m-cresol/p-cresol=42.5/- 57.5
(by mole of charged material) using formaldehyde as a condensing
agent.
[0073] Ingredient (B): (b1) A reaction product (esterification
rate: 50%) between 1 mole of the following phenol compound and 2
moles of 1,2-naphthoquinonediazido-5-sulfonyl chloride (5-NQD).
16
[0074] Ingredient C: The following compound (c1): 17
[0075] In 510 parts by weight of solvent mixture [ethyl
lactate/butyl acetate=9/1 (by weight)], 100 parts by weight of the
ingredient (A), 50 parts by weight of the ingredient (B), and 30
parts by weight of the ingredient (C) were dissolved, the resulting
solution was filtrated through a 0.2-.mu.m membrane filter and
thereby yielded a positive photoresist composition.
Examples 2 to 7 and Comparative Examples 1 to 5
[0076] A series of positive photoresist compositions was prepared
in the same manner as in Example 1, except that the ingredients (B)
and (C) used in Example 1 were changed to those indicated in Table
1.
1 TABLE 1 Ingredient (B) Ingredient (C) (compositional
(compositional ratio (wt. %)) ratio (wt. %)) Example 1 b1 (100) c1
(100) Example 2 b2 (100) c1 (100) Example 3 b1 (100) c2 (100)
Example 4 b1/b3 (80/20) c1 (100) Example 5 b1/b4 (80/20) c1 (100)
Example 6 b1 (100) c1/c3 (50/50) .sup. Example 7 b1 (100) c1/c4
(50/50) .sup. Comp. Ex. 1 b1 (100) c5 (100) Comp. Ex. 2 b1 (100) c6
(100) Comp. Ex. 3 b1 (100) c7 (100) Comp. Ex. 4 b5 (100) c1 (100)
Comp. Ex. 5 b6 (100) c1 (100)
[0077] b1: A reaction product (esterification rate: 50%) between 1
mole of the following phenol compound and 2 moles of 5-NQD: 18
[0078] b2: A reaction product (esterification rate: 40%) between 1
mole of the following phenol compound and 2 moles of 5-NQD: 19
[0079] b3: A reaction product (esterification rate: 75%) between 1
mole of the following phenol compound and 3 moles of 5-NQD: 20
[0080] b4: A reaction product (esterification rate: 67%) between 1
mole of the following phenol compound and 2 moles of 5-NQD: 21
[0081] b5: A reaction product (esterification rate: 67%) between 1
mole of 2,3,4-trihydroxybenzophenone and 2 moles of 5-NQD.
[0082] b6: A reaction product (esterification rate: 75%) of 1 mole
of 2,3,4,4'-tetrahydroxybenzophenone and 3 moles of 5-NQD.
[0083] c1: The following compound: 22
[0084] c2: The following compound: 23
[0085] c3: The following compound: 24
[0086] c4: The following compound: 25
[0087] c5: The following compound: 26
[0088] c6: The following compound: 27
[0089] c7: The following compound: 28
[0090] Table 2 shows that the photoresist compositions according to
the present invention comprising the specific photosensitizers and
sensitizers cause less shrink and are excellent in sensitivity and
definition.
[0091] Other embodiments and variations will be obvious to those
skilled in the art, and this invention is not to be limited to the
specific matters stated above.
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