U.S. patent application number 12/853640 was filed with the patent office on 2010-12-23 for process for preventing development defect and composition for use in the same.
Invention is credited to Yasushi Akiyama, Sung-Eun Hong, Tetsuo Okayasu, Kiyohisa Takahashi, Yusuke Takano.
Application Number | 20100324330 12/853640 |
Document ID | / |
Family ID | 29996619 |
Filed Date | 2010-12-23 |
United States Patent
Application |
20100324330 |
Kind Code |
A1 |
Akiyama; Yasushi ; et
al. |
December 23, 2010 |
Process for Preventing Development Defect and Composition for Use
in the Same
Abstract
The composition for preventing development-defects containing
(1) an ammonium salt, a tetraalkylammonium salt or a C.sub.1 to
C.sub.4 alkanolamine salt of C.sub.4 to C.sub.15
perfluoroalkylcarboxylic acid, C.sub.4 to C.sub.10
perfluoroalkylsulfonic acid and perfluoroadipic acid, or (2) a
fluorinated alkyl quaternary ammonium salt of inorganic acid,
wherein said surfactant is formed at the equivalent ratio of acid
to base of 1:1-1:3 is applied on a chemically amplified photoresist
coating on a substrate having a diameter of 8 inches or more. The
chemically amplified photoresist coating is baked before and/or
after applying the composition for preventing development-defects
described above. Then, the baked coating with the
development-defect preventing composition coating is exposed to
light, post-exposure-baked, and developed. By this process,
compared with the case of not using the composition for preventing
development-defects, the amount of reduction in film thickness of
the photoresist subsequent to development treatment is made further
bigger by 100 .ANG. to 600 .ANG., and the development-defects on a
substrate having a diameter of 8 inches or more is reduced as well
as a resist pattern having a good cross section form can be formed
without T-top form etc.
Inventors: |
Akiyama; Yasushi;
(Ogasa-gun, JP) ; Takano; Yusuke; (Ogasa-gun,
JP) ; Takahashi; Kiyohisa; (Ogasa-gun, JP) ;
Hong; Sung-Eun; (Ogasa-gun, JP) ; Okayasu;
Tetsuo; (Ogasa-gun, JP) |
Correspondence
Address: |
AZ ELECTRONIC MATERIALS USA CORP.;Industrial Property Department
70 Meister Avenue
Somerville
NJ
08876
US
|
Family ID: |
29996619 |
Appl. No.: |
12/853640 |
Filed: |
August 10, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10518105 |
Dec 10, 2004 |
7799513 |
|
|
PCT/JP03/07354 |
Jun 10, 2003 |
|
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12853640 |
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Current U.S.
Class: |
562/113 ;
562/596; 562/605; 564/291 |
Current CPC
Class: |
G03F 7/168 20130101;
G03F 7/11 20130101 |
Class at
Publication: |
562/113 ;
562/605; 562/596; 564/291 |
International
Class: |
C07C 309/02 20060101
C07C309/02; C07C 53/21 20060101 C07C053/21; C07C 55/14 20060101
C07C055/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 2002 |
JP |
2002-181127 |
Claims
1. A composition for preventing development-defects which contains
a surfactant and is used for the process of forming a resist
pattern that increases the amount of reduction in thickness of a
chemically amplified photoresist coating after development by 100
.ANG. to 600 .ANG. in comparison with the case of not applying the
composition for preventing development-defects, comprising: a step
of forming a chemically amplified photoresist coating on a
substrate having a diameter of 8 inches or more by application; a
step of applying a composition for preventing development-defects
containing a surfactant on the chemically amplified photoresist
coating; a step of baking after at least either the step of forming
the chemically amplified photoresist coating by application or the
step of applying the composition for preventing
development-defects; a step of selectively exposing the chemically
amplified photoresist coating; a step of post-exposure baking the
chemically amplified photoresist coating; and a step of developing
the chemically amplified photoresist coating, wherein said
surfactant is at least one member selected from the group
consisting of (1) an ammonium salt, a tetraalkylammonium salt or a
C.sub.1 to C.sub.4 alkanolamine salt of C.sub.4 to C.sub.15
perfluoroalkylcarboxylic acid, (2) an ammonium salt, a
tetraalkylammonium salt or a C.sub.1 to C.sub.4 alkanolamine salt
of C.sub.4 to C.sub.10 perfluoroalkylsulfonic acid, (3) a
quaternary ammonium salt of perfluoroadipic acid, and (4) a
fluorinated alkyl quaternary ammonium salt of inorganic acid which
is at least one member selected from the group consisting of
sulfric acid, hydrochrolic acid, nitric acid and hydroiodic acid,
at the same time said surfactant being one that is formed at the
equivalent ratio of acid to base of 1:1-1:3.
Description
[0001] This application is a continuation of U.S. Ser. No.
10/518,105 filed Dec. 10, 2004 which claims priority to United
States National Stage patent application under 35 U.S.C. .sctn.371
of International Patent Application No. PCT/JP03/07354, filed Jun.
10, 2003, which claims priority to Japanese Patent Application No.
2002-181127, filed Jun. 21, 2002.
TECHNICAL FIELD
[0002] This invention relates to a process for forming a resist
pattern with a good profile by using a positive-working chemically
amplified photoresist, and to a composition for preventing
development-defects used in this process. More particularly, it
relates to a process for forming a resist pattern by which a resist
pattern with a good profile can be formed all over the
large-diameter substrate when a resist pattern is formed by
pattern-wise exposing a large-diameter substrate having formed
thereon a chemically amplified photoresist coating followed by
development, and to a composition for preventing
development-defects used in this process.
BACKGROUND ART
[0003] In manufacturing semiconductor elements, lithographic
technology has been employed in which a photoresist coating is
formed on a substrate such as a silicon wafer and, after
selectively irradiating the coating with actinic rays, development
treatment is conducted to form a resist pattern on the substrate
thereby.
[0004] In recent years, in order to attain higher degree of
integration in LSI, patterning technology for forming patterns with
a finer line width in a lithographic process has been making a
rapid progress. For forming a pattern with a finer line width,
various proposals have been made with respect to all steps of the
lithography and all materials to be used therein including
photoresists, antireflective coatings, exposing methods, exposing
apparatus, developing agents, developing processes and developing
apparatus. For example, Japanese Patent Publication No. 2,643,056
and Japanese Unexamined Patent Publication No. H7-181685 describe
that an antireflective surface coating containing a
fluorine-containing compound with a low refractive index is formed
on a resist coating to prevent detrimental influences of reflected
light from the resist surface on formation of a resist pattern
thereby. When an antireflective coating is coated on a resist
layer, degree of vibration amplitude of the thickness of a resist
coating v.s. sensitivity curve becomes smaller. Therefore
fluctuation in sensitivity of resist becomes smaller even when
thickness of the resist layer fluctuates, which leads the advantage
of a decreased fluctuation in dimension of resist patterns formed.
In addition, the antireflective surface coating serves to decrease
standing wave to be caused by interference between incident light
and reflected light or between one reflected light and another
reflected light. Recently, technology of forming a resist pattern
having a desired line width without providing the antireflective
surface coating has also been developed. As examples thereof, there
are illustrated that an underlying substrate is made plane to
depress fluctuation in dimension due to fluctuation in thickness of
the resist layer as described above, or a mask pattern is finely
adjusted in advance according to fluctuation in dimension of the
resist.
[0005] With regard to exposing apparatus, there has been proposed a
process of using a light source emitting radiation of a short
wavelength, which is advantageous for formation of a superfiner
pattern, such as deep UV rays of KrF excimer laser (248 nm) or ArF
excimer laser (193 nm) or, further, X rays or electron beams, and
some of them have been coming into practice.
[0006] On the other hand, improvement in the yield of semiconductor
integrated circuits has been paid attention as an extremely
important matter in manufacturing them. There exist many factors by
which the yield of semiconductor integrated circuits is decided.
One of the factors is patterning failure upon forming a pattern
using a resist. This patterning failure of a resist pattern is
caused, for example, by the dust existing in the resist or sticking
onto the surface of the resist layer, by the deterioration of the
resist due to floating chemical species in the clean room, by the
coating failure of the resist or the like, or by the development
failure. As an example of deterioration due to chemical species
floating in a clean room, there is given a process using a
chemically amplified photoresist. In this process, the chemically
amplified photoresist is susceptible to influence of acidic
substances, basic substances and moisture in the atmosphere.
Therefore, when the period between pattern-wise exposure and PEB
(post exposure bake) is prolonged (post exposure delay) or due to
intermixing with a resist, there results a change in dimension of a
pattern, for example, by formation of a T-topped resist pattern in
the case where a positive-working photoresist is used as resist, or
formation of a round-topped resist pattern in the case where a
negative-working photoresist is used as resist.
[0007] In addition, defects upon developing a resist layer have
become a problem. As examples of defects upon development, there
are given formation of scum in line-and-space type resists and
hole-opening failure in contact hole type resists. Several causes
may be considered for the hole-opening failure of contact holes,
but the most popular hole-opening failure is one caused by residues
after development. As a cause of these defects, there is
illustrated insufficient dissolution of exposed portions into a
developing solution due to insufficient contact between the
developing solution containing water as a major component and the
surface of a resist coating upon bringing the developing solution
into contact with the resist surface, which leads to hole-opening
failure of portions which are designed to open essentially. It is
also thought that hardly-solubles in the developing solution might
re-deposit onto the surface of the resist upon rinsing with water
after development.
[0008] Further, it is necessary to enhance contrast of a resist in
order to form a finer pattern. In general, in order to improve
contrast of a contact hole type resist, a technique of increasing a
protecting ratio of hydrophilic groups in a major component polymer
is used with respect to, for example, positive-working chemically
amplified photoresists. However, when the protecting ratio is
increased, the resist surface is liable to become hydrophobic,
leading to deterioration in wetting properties for the developing
solution.
[0009] Various investigations have been conducted to solve the
above-described problems. For example, Japanese Unexamined Patent
Publication No. H9-246166 proposes to treat the surface of a
photoresist with plasma to render the surface hydrophilic thereby,
thus improving wetting properties of the resist for a developing
solution and decreasing development defects. This technique,
however, requires introduction of an additional apparatus for the
plasma treatment as well as includes the problem of decrease in
throughput.
[0010] In addition, various attempts for decreasing the development
defects by optimizing development sequence have been made as well.
For example, Japanese Examined Patent Publication No. H4-51020
describes to improve wetting properties of a positive-working
resist for a developing solution by adding an acetylenealcohol type
surfactant to the developing solution, thereby forming a pattern
having no development defects. Although some effects can be
obtained by this technique, the effects are at present still
insufficient in ultra-fine working using the aforesaid chemically
amplified photoresists. In addition, Japanese Unexamined Patent
Publication No. S61-179435 describes a method of optional formation
of surface coating, which is effective for improving wetting
properties for a developing solution, as well as a method of adding
a surfactant to the developing solution and a method of
plasma-treating the surface of a resist coating, for preventing
development defects resulting from lack of wetting properties for
the developing solution.
[0011] Particularly in the case where surface coating for
decreasing the development defects is formed on a chemically
amplified photoresist, there may cause a round-topped or a T-topped
pattern which may cause a trouble in an etching process when a
surface coating composition, which is coated to reduce this
development-defect, is compatible with a chemically amplified
resist. For example, in the patent publication of JP 2643056, as an
anti-reflective coating composition to form an anti-reflective
coating on a photoresist film, a composition comprising a
water-soluble polymer binder and a water-soluble fluorocarbon
compound (for example, a quaternary ammonium salt of
perfluorocarboxylic acid or perfluorosulfonic acid, and so on) was
disclosed. However, in said publication, there is no description of
a control on the amount of reduced thickness in film thickness
after developing a chemically amplified photoresist. In addition,
the method described in the publication has a problem. That is, in
the case where the anti-reflective coating composition described in
said publication is used, when the chemically amplified photoresist
is a positive-working photoresist, a pattern profile of a resist
pattern formed is likely to become a T-letter-shape (T-top), and
when being a negative-working photoresist, the pattern profile of
the resist pattern formed is likely to become a round shape
(round-top), thereby a problem of pattern dimension deterioration
being taken place.
[0012] Further, it is said that problems in attaining uniform
thickness of coating and uniform development to be caused with a
recent increase in diameter of a substrate such as a silicon wafer
make it difficult to form a finer pattern. For example, a paddle
developing method has so far been popularly employed for developing
a resist coating on the silicon wafer. In the paddle developing
method, a developing solution is dropped onto a resist coating
formed on a substrate, and the substrate is spun to form a thin
film of the developing solution all over the resist coating, thus
development of the resist coating being conducted. However, there
generates a difference in circumferential speed between the central
portion and the peripheral portion of the substrate, thereby a
difference in speed of the coating generating. Thus, developing
conditions become different between the central portion of the
wafer and the peripheral portion thereof. In this situation,
particularly when a chemically amplified photoresist is used as a
resist and a developing process of a large-diameter substrate
having a diameter of 8 inches or more is conducted, development
defects in the peripheral portion are caused in some cases which
have not conventionally been observed in treating a resist coating
formed on a substrate having a diameter of 6 inches or less.
[0013] Therefore, in order to improve a yield in manufacturing
semiconductor integrated circuits and so on, a process for forming
a resist pattern has been desired which enables one to reduce
development defects to be caused upon development including a
development defect of a chemically amplified photoresist in the
periphery of a larger diameter substrate such as a silicon wafer
caused by increasing in diameter of a substrate, and which does not
cause pattern failure such as T-top or round top after development
for coping with formation of finer patterns earnestly for forming a
finer resist pattern.
[0014] As a method to reduce such development defects, Japanese
Unexamined Patent Publication No. 2002-6514 describes that by
applying a composition for reducing a development-defect containing
a fluorine-containing surfactant on a chemically amplified
photoresist coating, the amount of reduced thickness in film
thickness of the chemically amplified photoresist after exposure to
light and development is made bigger by further 10 .ANG. to 500
.ANG. compared with the case without applying this composition for
reducing development-defects to form a pattern without
development-defect thereby. In this publication, as a surfactant
which is contained in a composition for reducing
development-defects of positive-working chemical amplified
photoresist, it is disclosed to use a surfactant which is formed
with excess of acid for the composition ratio of organic acid and
base and in which at least acid remains. However, it is difficult
to make this film thickness reduction large by using the
composition for reducing development-defects. When elimination of
T-top can be realized in the case where film thickness reduction
would be made large, there is a limit to form a pattern with good
profiles by using the composition for reducing development-defects.
In addition, in the publication, there is no description that a
film thickness reduction can be controlled quantitatively. Because
of this there is a problem that it is difficult to obtain the
composition for reducing development-defects which can provide an
optimal film thickness reduction in order to make the
pattern-profiler rectangular and good.
[0015] In consideration of the above-described situation, an object
of the present invention is to provide a process of forming a
resist pattern by using a composition for preventing development
defects by which development defects of a positive-working
chemically amplified photoresist is particularly reduced upon
developing of a large diameter substrate having a diameter of 8
inches or more and deterioration of pattern profiles does not be
caused such as T-top or round top which are inconvenient for an
etching step due to detrimental influences of a processing
atmosphere and intermixing between the surface coating and the
resist, wherein an occurrence of development defects on a substrate
with large diameter and a pattern profile after development can be
improved with optimal film thickness reduction by use of a
composition for preventing development defects which can make a
film thickness reduction after development bigger compared with the
process so far known as well as control the amount of film
thickness reduction, and coping with optimal film thickness
reduction is easy.
[0016] Another object of the present invention is to provide a
composition for preventing development-defects used in
above-described process.
[0017] As a result of intensive investigations, the inventors have
found that in a process of forming a resist pattern in which a
composition for preventing development-defects containing a
particular fluorine-containing surfactant is applied on a
positive-working chemically amplified photoresist to render the
surface thereof hydrophilic, then pattern-wise exposed to light and
developed, the amount of film thickness reduction subsequent to a
development of a positive-working chemically amplified photoresist
can be enlarged when the equivalent of acid and base which
constitute the surfactant is made excess of base compared with acid
upon a formation of a surfactant which is contained in the
composition for preventing development defects, and the amount of
film thickness reduction of a photoresist subsequent to a
development can be increased or decreased by controlling the amount
of the base used at this time, thus being achieved the present
invention.
DISCLOSURE OF THE INVENTION
[0018] The present invention provides a process for forming a
resist pattern, which increases the amount of reduction in
thickness of a chemically amplified photoresist coating after
development by 100 .ANG. to 600 .ANG. in comparison with the case
of not applying the composition for preventing development-defects,
comprising: a step of forming a chemically amplified photoresist
coating on a substrate having a diameter of 8 inches or more by
application; a step of applying a composition for preventing
development-defects containing a surfactant on the chemically
amplified photoresist coating; a step of baking after at least
either the step of forming the chemically amplified photoresist
coating by application or the step of applying the composition for
preventing development-defects; a step of selectively exposing the
chemically amplified photoresist coating; a step of post-exposure
baking the chemically amplified photoresist coating; and a step of
developing the chemically amplified photoresist coating,
wherein said surfactant is at least one member selected from the
group consisting of (1) an ammonium salt, a tetraalkylammonium salt
or a C.sub.1 to C.sub.4 alkanolamine salt of C.sub.4 to C.sub.15
perfluoroalkylcarboxylic acid, (2) an ammonium salt, a
tetraalkylammonium salt or a C.sub.1 to C.sub.4 alkanolamine salt
of C.sub.4 to C.sub.10 perfluoroalkylsulfonic acid, (3) a
quaternary ammonium salt of perfluoroadipic acid, and (4) a
fluorinated alkyl quaternary ammonium salt of inorganic acid which
is at least one member selected from the group consisting of
sulfric acid, hydrochrolic acid, nitric acid and hydroiodic acid,
at the same time said surfactant being one that is formed at the
equivalent ratio of an acid to a base of 1:1-1:3.
[0019] The present invention also provides a composition for
preventing development-defects which contains a surfactant and is
used for the process of forming a resist pattern that increases the
amount of reduction in thickness of a chemically amplified
photoresist coating after development by 100 .ANG. to 600 .ANG. in
comparison with the case of not applying the composition for
preventing development-defects, comprising: a step of forming a
chemically amplified photoresist coating on a substrate having a
diameter of 8 inches or more by application; a step of applying a
composition for preventing development-defects containing a
surfactant on the chemically amplified photoresist coating; a step
of baking after at least either the step of forming the chemically
amplified photoresist coating by application or the step of
applying the composition for preventing development-defects; a step
of selectively exposing the chemically amplified photoresist
coating; a step of post-exposure baking the chemically amplified
photoresist coating; and a step of developing the chemically
amplified photoresist coating,
wherein said surfactant is at least one member selected from the
group consisting of (1) an ammonium salt, a tetraalkylammonium salt
or a C.sub.1 to C.sub.4 alkanolamine salt of C.sub.4 to C.sub.15
perfluoroalkylcarboxylic acid, (2) an ammonium salt, a
tetraalkylammonium salt or a C.sub.1 to C.sub.4 alkanolamine salt
of C.sub.4 to C.sub.10 perfluoroalkylsulfonic acid, (3) a
quaternary ammonium salt of perfluoroadipic acid, and (4) a
fluorinated alkyl quaternary ammonium salt of inorganic acid which
is at least one member selected from the group consisting of
sulfric acid, hydrochrolic acid, nitric acid and hydroiodic acid,
at the same time said surfactant being one that is formed at the
equivalent ratio of acid to base of 1:1-1:3.
CONCRETE MODE OF THE INVENTION
[0020] The present invention is described in more detail below. In
a resist pattern forming process of the present invention, the
amount of reduction in thickness of the chemically amplified
photoresist coating after development is made bigger by 100 .ANG.
to 600 .ANG. in comparison with the case of not applying the
composition for preventing development-defects on the chemically
amplified photoresist coating. In order to make the amount of
reduction in thickness of photoresist film after developing
treatment big in amount, when forming the surfactant described in
above items (1) to (4) which is contained in the composition for
preventing development-defects, an equivalent quantity of base is
made excessive to that of acid in the present invention.
[0021] As an organic acid which is used upon forming surfactants
(1) to (3) described above which are contained in the composition
for preventing development-detects, there are exemplified
preferably functional fluorocarbon compounds, particularly
perfluoroalkylcarboxylic acid such as C.sub.4 to C.sub.15
perfluoroalkylcarboxylic acid, perfluoroalkylsulfonic acid such as
C.sub.4 to C.sub.10 perfluoroalkylsulfonic acid, and
perfluoroadipic acid. As a base, there are exemplified ammonia,
amines and quaternary ammonium alkyl hydroxide and ammonia,
tetramethylammonium hydroxide and C.sub.1 to C.sub.4 alkanolamine
are particularly preferred. The organic acid and the base such as
amine, quaternary ammonium alkyl hydroxide or ammonia are mixed in
an aqueous solution, and for example, an ammonium salt, a
tetraalkylammonium salt such as a tetramethylammonium salt or an
amine salt such as C.sub.1 to C.sub.4 alkanol amine salt, of an
organic acid is formed. When forming an above-described surfactant
(4), an inorganic acid such as sulfuric acid, hydrochloric acid,
nitric acid, hydroiodic acid, and the like is used as the acid, and
on the other side, fluorinated alkyl quaternary ammonium hydroxide
etc. is used as the base.
[0022] In the present invention, these surfactants are formed by
solving the determined amount of the acid and the base in water. At
this time, the amount of the formed surfactant in the aqueous
solution is made 0.1 to 25 weight-%, more preferably 2 to 4
weight-%. The aqueous solution is used as a composition for
reducing development defects. If necessary, additives are further
solved in this aqueous solution and the resulting solution may be
used as a composition for preventing development-defects. In
addition, the surfactant-containing aqueous solution may be formed
by adjusting the concentration, for example, by adding the
preformed high concentration aqueous surfactant to water containing
additives if necessary or vise versa by diluting the preformed high
concentration aqueous surfactant with an additive-containing
aqueous solution if necessary.
[0023] In this situation, the amount of reduction in thickness of
the resist layer can be optimized by properly adjusting the mixing
ratio of the above-described acid and base such as an amine, a
quaternary ammonium hydroxide, and ammonia to adjust basicity of
the composition in consideration of the kind of a chemically
amplified photoresist to be used or processing conditions. It means
that, upon forming a surfactant, a mixing amount of the acid and
the base is controlled as that the equivalent of a base is
excessive to the equivalent of an acid in the present invention. At
this time, the amount of reduction in film thickness after
development of photoresist is increased by increasing the amount of
base to be used. Accordingly the amount of reduction in film
thickness upon developing resist can be controlled to obtain an
optimized result by properly adjusting the mixing ratio of the acid
to the base such as an amine, a quaternary ammonium hydroxide, and
ammonia in accordance with the kind of a chemically amplified
photoresist to be used or processing conditions. In the composition
for preventing development-defects to be applied for
positive-working chemically amplified photoresist, the ratio of
acid to base, for example amine, is usually 1:1 to 1:3, preferably
1:1 to 1:2 in equivalent ratio.
[0024] In the composition for preventing development defects of the
present invention, a water-soluble resin and a various kinds of
additives can be formulated within the limit wherein its
performance is not damaged, if necessary.
[0025] As a water-soluble resin which is used for the composition
for preventing development defects of the present invention, there
can be illustrated, for examples, poly(vinyl alcohol), poly(acrylic
acid), poly(vinylpyrrolidone), poly(.alpha.-trifuluoromethyl
acrylic acid), poly(vinyl methyl ether-co-maleic anhydride),
poly(ethylene glycol-co-propylene gycol),
poly(N-vinylpyrrolidone-co-vinyl acetate),
poly(N-vinylpyrrolidone-co-vinyl alcohol),
poly(N-vinylpyrrolidone-co-acrylic acid),
poly(N-vinylpyrrolidone-co-methyl acrylate),
poly(N-vinylpyrrolidone-co-methacrylic acid),
poly(N-vinylpyrrolidone-co-methyl methacrylate),
poly(N-vinylpyrrolidone-co-maleic acid),
poly(N-vinylpyrrolidone-co-dimethyl maleate),
poly(N-vinylpyrrolidone-co-maleic anhydride),
poly-(N-vinylpyrrolidone-co-itaconic acid),
poly(N-vinylpyrrolidone-co-methyl itaconate),
poly(N-vinylpyrrolidone-co-itaconic anhydride), fluorinated
polyether, etc. Above all, poly(acrylic acid),
poly(vinylpyrrolidone), and fluorinated polyether are especially
preferred.
[0026] As the additives to be used in the composition for
preventing development-defects of the present invention, there can
be illustrated, for example, surfactants to be added for improving
coating properties, such as nonionic surfactants, anionic
surfactants and amphoteric surfactants. As the nonionic
surfactants, there are exemplified polyoxyethylene alkyl ethers
such as polyoxyethylene lauryl ether, polyoxyethylene oleyl ether
and polyoxyethylene cetyl ether, polyoxyethylene fatty acid
diesters, polyoxyfatty acid monoester,
polyoxyethylene-polyoxypropylene block polymer, and acetylene
glycol derivatives. As the anionic surfactants, there are
exemplified ammonium salts or organic amine salts of alkyldiphenyl
ether disulfonic acid, ammonium salts or organic amine salts of
alkyldiphenyl ether sulfonic acid, ammonium salts or organic amine
salts of alkylbenzenesulfonic acid, ammonium salts or organic amine
salts of polyoxyethylene alkyl ether sulfuric acid, and ammonium
salts or organic amine salts of alkyl sulfuric acid. As the
amphoteric surfactants, there are exemplified
2-alkyl-N-carboxymethyl-N-hydroxyethyl-imidazolinium betaine and
laurylamidopropyl hydroxysulfone betaine.
[0027] Further, as water to be used in the composition for
preventing development-defects of the present invention, water from
which organic impurities, metal ions, etc. have been removed by
distillation, an ion-exchange treatment, a treatment through filter
or various adsorption treatments are preferably illustrated.
[0028] Additionally, in order to improve coating properties, a
water-soluble organic solvent can be used together with water. The
water-soluble organic solvent is not particularly limited as long
as it can be soluble in water in a concentration of 0.1 wt % or
more. Examples of the organic solvent include alcohols such as
methyl alcohol, ethyl alcohol and isopropyl alcohol, ketones such
as acetone and methyl ethyl ketone, esters such as methyl acetate
and ethyl acetate, and polar solvents such as dimethylformamide,
dimethylsulfoxide, methyl cellosolve, cellosolve, butyl cellosolve,
cellosolve acetate, butylcarbitol and carbitol acetate. These
specific examples are merely illustrated as examples of the organic
solvents, and the organic solvents to be used in the present
invention are not limited only to these solvents.
[0029] In addition, optimization of the amount of reduction in
thickness of the resist coating in the present invention may also
be attained by properly adjusting baking time or baking temperature
of the resist and the composition for preventing
development-defects as well as optimization by the composition
itself for reducing development defects. As to the prebaking
temperature for the resist, there are generally two types in
accordance with photoresist compositions to be used. That is, one
type requires a high energy and generally requires to bake at a
temperature of about 100.degree. C. to about 150.degree. C., and
another type does not require so much energy in comparison with the
former and requires to bake at a temperature of 100.degree. C. or
lower. In addition, prebaking temperature for the composition for
preventing development-defects is generally 60.degree. C. to
100.degree. C. which is high enough to remove the solvent. Further,
post-exposure baking of the resist is generally about 100.degree.
C. to about 150.degree. C. For example, in the case where T-tops
are formed after development, formation of such T-tops can be
avoided in some cases by such combination of baking temperatures
for the resist and the composition for preventing
development-defects that resist-prebaking temperature is set at a
lower level while prebaking temperature for the composition for
preventing development-defects at a level of 100.degree. C. or
higher. In addition, too much reduction in thickness of the resist
coating disadvantageous in an etching step can be avoided by
optionally delaminating or dissolving away the composition for
preventing development-defects after exposure.
[0030] Thickness of the coating of the composition for preventing
development-defects in the present invention may be such that it
provides enough chemical action to more reduce thickness of the
resist coating in comparison with the case of not applying the
composition for preventing development-defects. The thickness of
the coating is preferably 80 .ANG. to 10,000 .ANG., more preferably
330 .ANG. to 990 .ANG.. Coating of the composition for preventing
development-defects can be conducted by any of known coating
methods such as a spin coating method.
[0031] The chemically amplified photoresist to be used as a resist
in the present invention may be any of known positive-working
chemically amplified photoresists. As the positive-working
chemically amplified photoresist, there are known a number of ones
including that which is composed of a combination of a polymer
wherein polyhydroxystyrene is protected with t-butoxycarbonyl group
and a photo acid generator (see, H. Ito and C. G. Willson: Polym.
Eng. Sci., 23, 1012 (1983)). Thickness of the coating may be such
that a resist pattern obtained after development can suitably exert
its performance during etching in the etching step, and is
generally about 0.3 to 1.0 .mu.m.
[0032] The pattern-forming method of the present invention can
favorably be applied upon formation of a pattern on a substrate
having a diameter of 8 inches or more. As the substrate, a silicon
substrate is common, and of course may be those wherein a metal
layer or an oxide or nitride layer such as silicon oxide, silicon
nitride or silicon oxide nitride is formed on silicon. In addition,
the substrate itself is not limited to silicon but may be any of
substrate materials having so far been used for manufacturing IC
such as LSI.
[0033] As to the method for coating the chemically amplified
photoresist and baking of the chemically amplified photoresist
layer and the layer of reducing development defect compositions,
exposing method, developing agents, and developing method, any ones
or any conditions having so far been employed for forming a resist
pattern using a chemically amplified photoresist may be employed.
Further, as an exposing light source to be used in the exposing
step, any of UV rays, deep UV rays, X rays, and electron beams may
be used.
BEST MODE FOR PRACTICING THE INVENTION
[0034] The present invention will now be described more
specifically by reference to Examples which, however, are not to be
construed to limit the present invention in any way.
Example-1
[0035] 1.3 parts by weight of polyacrylic acid having weight
average molecular weight of 3,000 as determined by polystyrene
standards as a water-soluble polymer, 2.0 parts by weight of
perfluoro-octylic acid (C.sub.7F.sub.15COOH) as an organic acid,
0.46 parts by weight of tetramethylammonium hydroxide (TMAH)
(equivalent ratio (mole) of organic acid and base is 1:1.04) as a
base were mixed up. Pure water was added thereto to make the total
amount 100 parts by weight. Then, the solution was solved
homogeneously at room temperature, and filtered with a 0.1
.mu.m-filter to obtain the composition for preventing
development-defects.
[0036] On the other hand, a positive-working photoresist comprising
acetal type polymer manufactured by Clariant (Japan) K. K. (AZ
DX3301P, `AZ` is a registered trade mark.) was applied on an 8
inches silicon wafer by a spin coater made by Tokyo Electron Co.
(Mark 8). It was pre-baked on a hot plate at 90.degree. C. for 90
seconds to form a photoresist film of 480 nm in thickness on a
silicon wafer. The film thickness was measured by film thickness
measuring equipment SM300 manufactured by Prometric Co.
[0037] Subsequently the above described composition for preventing
development-defects was applied on the photoresist film by using
the same spin coater as the above. It was then pre-baked on a hot
plate at 90.degree. C. for 60 seconds to form a film for preventing
development-defects on a photoresist film of 450 .ANG. in
thickness. Next, exposure to light was conducted by using KrF
reduced projection exposure equipment, FPA 3000-EX5, PEB was
conducted on a hot plate at 110.degree. C. for 60 seconds. Using
alkali developer, AZ 300MIF Developer (2.38 weight %
tetramethylammonium hydroxide aqueous solution; `AZ` is a
registered trade mark.) as a developer, it was paddle-developed on
the condition of 23.degree. C. for 1 minute, to obtain a resist
pattern having 1:1 line and space width. And also the film
thickness after development was measured using the same equipment
as one described above. The amount of film reduction in thickness
was obtained by deducting the film thickness after development from
one before development. The cross sectional form of the formed
resist pattern was observed by Scanning Electronic Microscope
(SEM). Observation result of the cross-sectional form of the resist
pattern and the amount of film reduction in thickness are shown in
the Table-1 described below.
Examples 2 to 5
[0038] The same manner was taken as in Example-1 except that the
equivalent (mole) ratios of base were made as described in Table-1
below and the results in Table-1 were obtained.
TABLE-US-00001 TABLE 1 Film Film Reduction thickness thickness
amount in before after film Development Development thickness
Pattern (.ANG.) (.ANG.) (.ANG.) Organic Acid Base Profile Example-1
4819 4589 230 1 1.04 almost rectangular Example-2 4789 4460 329 1
1.25 rectangular Example-3 4796 4395 401 1 1.38 rectangular
Example-4 4837 4379 458 1 1.52 almost rectangular Example-5 4809
4299 510 1 2.00 almost rectangular
Comparative Example-1
[0039] In the same manner as in above described Example-1, the
silicon wafer on which a positive-working chemically amplified
photoresist was applied was prepared. Then, exposure to light, PEB
and development were conducted in the same manner as in Example-1
except that the composition for preventing development-defects was
not applied thereon and a pattern form of resist cross section was
observed and the amount of reduction in film thickness was
measured. The result is shown in Table-2 described below.
TABLE-US-00002 TABLE 2 Film thickness Film thickness Reduction
amount before after in film Development Development thickness
Pattern (.ANG.) (.ANG.) (.ANG.) Profile Comparative 4801 4698 103
T-top Example-1
Comparative Example-2
[0040] Perfluorooctyl acid (C.sub.7F.sub.15COOH) was added into the
composition used in the Example-1 described above, mixed up to be
excessive by acid having 1:0.9 of molar ratio of acid to base. Pure
water was added therein, followed by solving at room temperature
homogeneously. Next, it was filtered through 0.1 .mu.m filter to
obtain the composition for preventing development-defects
containing a surfactant having the almost same concentration as in
Example-1. Treating in the same manner as in Example-1 except for
using this composition for preventing development-defects, the
result in Table-3 was obtained.
Comparative Example-3
[0041] Treating in the same manner as in Comparative Example-1
except for making the molar ratio of perfluorooctylic acid and base
1:0.95, the result in Table-3 was obtained.
TABLE-US-00003 TABLE 3 Film Reduction Film thickness thickness
amount in before after film Development Development thickness
(.ANG.) (.ANG.) (.ANG.) Acid Base Pattern Profile Comparative 4820
4649 171 1 0.90 T-top Example-2 Comparative 4805 4624 181 1 0.95
T-top Example-3
[0042] As being obvious from the results described in the above
Table-1 and Table-2, it was confirmed that the reduction amount in
film thickness is likely to increase as addition of a base and to
decrease as addition of an acid. And then if these ratios of base
to be added are made within a certain limit, the resist pattern
profile to be formed can be greatly improved.
EFFECTS OF INVENTION
[0043] As described above in details, by using the composition for
preventing development-defects of the present invention, T-top
pattern form of a chemically amplified positive-working photoresist
can be eliminated, for example, which is caused by FED or by
intermixing with resist, and an excellent pattern profile can be
made having no development-defects even in the substrate with a
large diameter of 8 inches or more.
INDUSTRIAL APPLICABILITY
[0044] The process and composition for preventing
development-defects of the present invention are the good resist
pattern-forming method used upon forming a chemically amplified
photoresist coating on a substrate with a large diameter and the
composition for preventing development-defects used for the
method.
* * * * *