U.S. patent application number 09/742392 was filed with the patent office on 2001-12-06 for undercoating composition for photolithographic resist.
Invention is credited to Hirosaki, Takako, Iguchi, Etsuko, Kobayashi, Masakazu.
Application Number | 20010049072 09/742392 |
Document ID | / |
Family ID | 27283071 |
Filed Date | 2001-12-06 |
United States Patent
Application |
20010049072 |
Kind Code |
A1 |
Hirosaki, Takako ; et
al. |
December 6, 2001 |
Undercoating composition for photolithographic resist
Abstract
Disclosed is a novel undercoating solution for the formation of
an antireflection undercoating layer to intervene between the
surface of a substrate and a photoresist layer to be patterned in
the manufacturing process of semiconductor devices with an object
to prevent adverse influences of the light reflecting at the
substrate surface on the cross sectional profile of the patterned
resist layer. The undercoating composition is a uniform solution
which comprises: (A) a nitrogen-containing organic compound having,
in a molecule, at least two amino groups substituted by at least
one substituent group selected from the group consisting of
hydroxyalkyl groups and alkoxyalkyl groups such as an
N,N-substituted benzoguanamine compound; (B) an organic acid or an
inorganic acid of which the acid residue contains at least one atom
of sulfur such as methane-sulfonic acid and dodecylbenzene sulfonic
acid; and (C) an organic solvent such as propyleneglycol monomethyl
ether. The undercoating solution further optionally contains a
light-absorbing compound such as bis(4-hydroxyphenyl) sulfone and
9-hydroxymethyl anthracene.
Inventors: |
Hirosaki, Takako;
(Kanagawa-ken, JP) ; Iguchi, Etsuko; (Machida-shi,
JP) ; Kobayashi, Masakazu; (Chigasaki-shi,
JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
27283071 |
Appl. No.: |
09/742392 |
Filed: |
December 22, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09742392 |
Dec 22, 2000 |
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09493098 |
Jan 28, 2000 |
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6284428 |
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Current U.S.
Class: |
430/270.1 |
Current CPC
Class: |
G03F 7/091 20130101;
Y10S 430/128 20130101 |
Class at
Publication: |
430/270.1 |
International
Class: |
G03F 007/004 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 28, 1999 |
JP |
11-20506 |
Jan 28, 1999 |
JP |
11-20507 |
Jan 28, 1999 |
JP |
11-20508 |
Claims
What is claimed is:
1. An undercoating composition for photolithographic resist which
comprises, as a uniform solution: (A) a nitrogen-containing organic
compound having, in a molecule, at least two amino groups
substituted by at least one substituent group selected from the
group consisting of hydroxyalkyl groups and alkoxyalkyl groups; (B)
an organic acid or an inorganic acid of which the acid residue
contains at least one atom of sulfur; and (C) an organic
solvent.
2. An undercoating composition for photolithographic resist which
comprises, as a uniform solution: (A1) a benzoguanamine compound
represented by the general formula 5in which R is a hydrogen atom
or a monovalent hydrocarbon group and at least two of R.sup.1,
R.sup.2, R.sup.3 and R.sup.4 are each a hydroxyalkyl group or an
alkoxyalkyl group, the rest, if any, each being a hydrogen atom, or
an oligomer thereof; (B) an organic acid or an inorganic acid of
which the acid residue contains at least one atom of sulfur; and
(C) an organic solvent.
3. The undercoating composition for photolithographic resist as
claimed in claim 2 in which the amount of the component (B) is in
the range from 0.1 to 10 parts by weight per 100 parts by weight of
the component (A1).
4. The undercoating composition for photolithographic resist as
claimed in claim 2 in which the monovalent hydrocarbon group
denoted by R is a hydrogen atom.
5. The undercoating composition for photolithographic resist as
claimed in claim 2 in which the hydroxyalkyl group denoted by
R.sup.1, R.sup.2, R.sup.3 or R.sup.4 is hydroxymethyl group.
6. The undercoating composition for photolithographic resist as
claimed in claim 2 in which the alkoxyalkyl group denoted by
R.sup.1, R.sup.2, R.sup.3 or R.sup.4 is selected from the group
consisting of methoxymethyl group, ethoxymethyl group,
propoxymethyl group and butoxymethyl group.
7. An undercoating composition for photolithographic resist which
comprises, as a uniform solution: (A) a nitrogen-containing organic
compound having, in a molecule, at least two amino groups
substituted by at least one substituent group selected from the
group consisting of hydroxyalkyl groups and alkoxyalkyl groups;
(B1) an organic acid of which the acid residue has a hydro-carbon
group substituted for at least a part of the hydrogen atoms by
fluorine atoms; (C) an organic solvent; and (D) a light-absorbing
compound.
8. The undercoating composition for photolithographic resist as
claimed in claim 7 in which the organic acid as the component (B1)
is selected from the group consisting of aliphatic carboxylic
acids, aliphatic sulfonic acids, alkylbenzene carboxylic acids and
alkylbenzene sulfonic acids having at least one fluorine atom
substituting for the hydrogen atom.
9. The undercoating composition for photolithographic resist as
claimed in claim 7 in which the nitrogen-containing organic
compound as the component (A) is a triazine compound.
10. The undercoating composition for photolithographic resist as
claimed in claim 9 in which the triazine compound is a
benzoguanamine compound.
11. The undercoating composition for photolithographic resist as
claimed in claim 8 in which the component (B1) is an aliphatic
sulfonic acid having at least one fluorine atom substituting for
the hydrogen atom.
12. The undercoating composition for photolithographic resist as
claimed in claim 11 in which the component (B1) is trifluoromethane
sulfonic acid or nonafluorobutane sulfonic acid.
13. The undercoating composition for photolithographic resist as
claimed in claim 7 in which the light-absorbing compound as the
component (D) is selected from the group consisting of benzophenone
compounds, bisphenyl sulfone compounds, bisphenyl sulfoxide
compounds and anthracene compounds.
14. The undercoating composition for photolithographic resist as
claimed in claim 13 in which the component (D) is an anthracene
compound.
15. The undercoating composition for photolithographic resist as
claimed in claim 14 in which the anthracene compound is
9-hydroxymethyl anthracene or 9-anthracene carboxylic acid.
16. The undercoating composition for photolithographic resist as
claimed in claim 7 in which the amount of the component (B1) is in
the range from 0.1 to 10 parts by weight per 100 parts by weight of
the component (A).
17. The undercoating composition for photolithographic resist as
claimed in claim 7 in which the amount of the component (D) is in
the range from 5 to 70% by weight based on the total amount of the
components (A), (B1) and (D).
18. An undercoating composition for photolithographic resist which
comprises, as a uniform solution: (A) a nitrogen-containing organic
compound having, in a molecule, at least two amino groups
substituted by at least one substituent group selected from the
group consisting of hydroxyalkyl groups and alkoxyalkyl groups;
(B2) an acid selected from the group consisting of aliphatic
carboxylic acids, aliphatic sulfonic acids, alkylbenzene carboxylic
acids, alkylbenzene sulfonic acids and inorganic sulfur-containing
acids; (C) an organic solvent; and (D) a light-absorbing
compound.
19. The undercoating composition for photolithographic resist as
claimed in claim 18 in which the nitrogen-containing organic
compound as the component (A) is a triazine compound.
20. The undercoating composition for photolithographic resist as
claimed in claim 19 in which the triazine compound is a
benzoguanamine compound.
21. The undercoating composition for photolithographic resist as
claimed in claim 18 in which the acid as the component (B2) is
selected from the group consisting of aliphatic sulfonic acids,
alkylbenzene sulfonic acids and sulfuric acid.
22. The undercoating composition for photolithographic resist as
claimed in claim 21 in which the acid as the component (B2) is
methanesulfonic acid or dodecylbenzene sulfonic acid.
23. The undercoating composition for photolithographic resist as
claimed in claim 18 in which the light-absorbing compound as the
component (D) is selected from the group consisting of benzophenone
compounds, bisphenyl sulfone compounds, bisphenyl sulfoxide
compounds and anthracene compounds.
24. The undercoating composition for photolithographic resist as
claimed in claim 18 in which the component (D) is an anthracene
compound.
25. The undercoating composition for photolithographic resist as
claimed in claim 24 in which the anthracene compound is
9-hydroxymethyl anthracene or 9-anthracene carboxylic acid.
26. The undercoating composition for photolithographic resist as
claimed in claim 18 in which the amount of the component (B2) is in
the range from 0.1 to 10 parts by weight per 100 parts by weight of
the component (A).
27. The undercoating composition for photolithographic resist as
claimed in claim 18 in which the amount of the component (D) is in
the range from 5 to 70% by weight based on the total amount of the
components (A), (B2) and (D).
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to an undercoating composition
for photolithographic resist in the manufacture of various kinds of
electronic devices such as semiconductor devices and liquid crystal
display panels. More particularly, the invention relates to a
coating composition for the formation of an undercoating layer
between the surface of a substrate and a layer of a photoresist
composition which is patterned by patternwise exposure to actinic
rays such as excimer laser beams to give a patterned resist layer
having an excellently orthogonal cross sectional profile without
irregularity such as trailing skirts and notchings.
[0002] In the patternwise exposure of a photoresist layer on a
substrate surface with actinic rays in the manufacture of very fine
semiconductor devices by utilizing the photolithographic technology
for patterning of the photoresist layer, a problem is encountered
that the resist layer obtained by patterning has a more or less
irregular cross sectional profile by the influences of the standing
waves due to the reflection of the exposure light at the substrate
surface disadvantegeously affecting the results of the subsequent
processes utilizing the patterned resist layer as a masking. It is
conventionally practiced accordingly to provide an antireflection
film as an undercoating layer between the substrate surface and the
photoresist layer with an object to solve this problem.
[0003] Along with the trend in the electronic technology toward
more and more increasing fineness of semiconductor devices such as
integrated circuits, the actinic rays for patternwise exposure of
the photoresist layer is also under continuous shift toward those
of a shorter wavelength such as KrF and ArF excimer laser beams as
well as X-rays and electron beams. When excimer laser beams are
used as the exposure light, the antireflection film on the
substrate surface is formed by using a variety of undercoating
compositions comprising, as the essential ingredients, a
film-forming resinous compound, a light-absorbing compound to
absorb the reflecting light from the substrate surface and a
crosslinking agent to effect thermal crosslinking of the
ingredients. In Japanese Patent Kokai 8-87115, 9-292715 and
10-228113, for example, an under-coating composition is disclosed
which contains a crosslinking agent substituted by hydroxyalkyl
groups and/or alkoxyalkyl groups, a dye compound selected from
benzophenone compounds, diphenylsulfone compounds and sulfoxide
compounds as the light-absorbing agent and an acrylic resin as the
film-forming ingredient.
[0004] Investigations are now under way to develop a film-forming
resin which is imparted with light-absorptivity by introducing
light-absorbing substituent groups to the skeletal structure of the
resin molecules. Examples of an undercoating composition containing
such a dual-service resinous compound heretofore proposed include
the antireflection undercoating compositions comprising two
essential ingredients exemplified by the antireflection
undercoating composition disclosed in Japanese Patent Kokai
10-204328 which contains a resin as a binder having quinolinyl
groups, optionally, substituted by a heterocyclic group with an
atom of nitrogen, oxygen or sulfur as the heteroatom, phenanthrenyl
groups, acridinyl groups or alkyleneanthryl groups and a
crosslinking agent such as glycoluril and the antireflection
undercoating composition disclosed in WO 97/07145 which contains a
resin obtained by the polymerization of a dye compound substituted
by a group having an anthracene ring or naphthalene ring with an
epoxy resin and a crosslinking agent such as melamine, urea,
benzoguanamine and glycoluril.
[0005] Although the antireflection undercoating film formed by
using the above described undercoating compositions is in fact
effective to some extent for improving the cross sectional profile
of the patterned resist layer formed thereon by suppressing the
adverse influences of the standing waves at least when fineness of
resist patterning is within a conventional range, the improvements
obtained thereby are not quite satisfactory when further upgrading
is required for the accuracy and fineness of the patterned resist
layer resulting in irregularity in the cross sectional profile of
the patterned resist layer such as skirt trailing and notching at
the base part of the resist layer in contact with the substrate
surface not to give an excellently orthogonal cross sectional
profile.
[0006] A problem recently raised in connection with an
antireflection undercoating composition containing a
light-absorbing compound as a separate ingredient is contamination
of various parts of the apparatuses by the deposition of the
light-absorbing compound which is sometimes liable to
sublimation.
[0007] Besides, a further proposal is made in Japanese Patent Kokai
10-301268 for an antireflection coating composition comprising
hexamethoxymethyl melamine, propyleneglycol mono-methyl ether
acetate and 2,4-dimethylbenzene sulfonic acid, which, however, does
not give an antireflection undercoating film capable of fully
suppressing the adverse influences of standing waves and
controlling the cross sectional profile of the patterned resist
layer.
SUMMARY OF THE INVENTION
[0008] The present invention accordingly has an object, in view of
the above described problems and disadvantages in the undercoating
compositions of the prior art, to provide a novel and improved
undercoating composition for the formation of an antireflection
undercoating film in the photolithographic patterning of a
photoresist layer, by use of which a patterned resist layer having
an excellently orthogonal cross sectional profile standing upright
on the substrate surface without irregularity such as trailing
skirts and notchings can be obtained even by the use of actinic
rays of short wavelengths for light-exposure including not only
excimer laser beams but also X-rays and electron beams for the
purpose of accomplishing increased fineness of patterning. The
invention further has an object to provide an undercoating
composition for photolithography capable of giving an undercoating
layer exhibiting a high etching rate in compliance with the trend
in the photoresist layer toward a smaller and smaller thickness of
the layer.
[0009] Thus, the undercoating composition for photolithographic
resist provided by the present invention is a uniform solution
which comprises:
[0010] (A) a nitrogen-containing organic compound having, in a
molecule, at least two amino groups substituted by at least one
substituent group selected from hydroxyalkyl groups and alkoxyalkyl
groups;
[0011] (B) an organic acid or an inorganic acid of which the acid
residue contains at least one atom of sulfur; and
[0012] (C) an organic solvent.
[0013] As a first embodiment of the above defined undercoating
composition, the invention provides an undercoating composition for
photolithographic resist in the form of a uniform solution which
comprises:
[0014] (A1) a benzoguanamine compound represented by the general
formula 1
[0015] in which R is a hydrogen atom or a monovalent hydrocarbon
group and at least two of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are
each a hydroxyalkyl group or an alkoxyalkyl group, the rest, if
any, each being a hydrogen atom, or an oligomer thereof;
[0016] (B) an acid of which the acid residue contains at least one
atom of sulfur; and
[0017] (C) an organic solvent.
[0018] As a second embodiment of the above defined undercoating
composition, the undercoating composition of the invention for
photolithographic resist in the form of a uniform solution
comprises:
[0019] (A) a nitrogen-containing organic compound defined above as
the component (A);
[0020] (B1) an organic acid of which the acid residue has a
hydro-carbon group substituted for at least a part of the hydrogen
atoms by fluorine atoms;
[0021] (C) an organic solvent; and
[0022] (D) a light-absorbing compound.
[0023] As a third embodiment of the above defined undercoating
composition, the invention provides an undercoating composition for
photolithographic resist in the form of a uniform solution which
comprises:
[0024] (A) a nitrogen-containing organic compound having, in a
molecule, at least two amino groups substituted by at least one
substituent group selected from hydroxyalkyl groups and alkoxyalkyl
groups;
[0025] (B2) an acid selected from the group consisting of aliphatic
carboxylic acids, aliphatic sulfonic acids, alkylbenzene carboxylic
acids, alkylbenzene sulfonic acids and inorganic sulfur-containing
acids;
[0026] (C) an organic solvent; and
[0027] (D) a light-absorbing compound.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] As is described above, the undercoating composition
according to the present invention comprises, as the essential
ingredients, the components (A), (B) and (C), of which the
component (C) is an organic solvent to dissolve the other essential
ingredients and optional additives to form a uniform solution. The
component (A), which is a nitrogen-containing organic compound
having, in a molecule, at least two amino groups substituted by at
least one substituent group selected from hydroxyalkyl groups and
alkoxyalkyl groups, is, in particular according to the first
embodiment of the invention, (Al) a benzoguanamine compound
represented by the above given general formula (I), in which R is a
hydrogen atom or a monovalent hydrocarbon group and at least two of
R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each a hydroxyalkyl group
or an alkoxyalkyl group, the rest, if any, each being a hydrogen
atom, or an oligomer thereof. While the monovalent hydrocarbon
group denoted by R in the general formula (I) can be selected
preferably from the group consisting of alkyl groups, aralkyl
groups and aryl groups, it is more preferable that the group
denoted by R is a hydrogen atom.
[0029] The hydroxyalkyl group which can be the group denoted by
each of R.sup.1 to R.sup.4 is preferably a hydroxyalkyl group
having 1 to 4 carbon atoms or, more preferably, hydroxymethyl
group. On the other hand, the alkoxyalkyl group is preferably that
of which the alkoxy group and alkyl group each have 1 to 4 carbon
atoms or, more preferably, selected from methoxymethyl,
ethoxymethyl, propoxymethyl and butoxymethyl groups. Although each
of the groups denoted by R.sup.1 to R.sup.4 can be the same as or
different from the others, it is essential that at least two of the
four are the above mentioned hydroxyalkyl groups or alkoxyalkyl
groups, the rest, if any, each being a hydrogen atom. It is
preferable that the two amino groups bonded the triazine ring are
each substituted by at least one hydroxyalkyl group or alkoxyalkyl
group. The component (A1) is not limited to the above described
benzoguanamine compound per se but can be an oligomer of the
benzoguanamine compound.
[0030] A variety of commercial products produced by Mitsui Cyanamid
Co. and available on the market can be used as the component (Al)
in the inventive undercoating composition including Cymel 1123 as a
methoxymethylated ethoxymethylated benzoguanamine, Cymel 1123-10 as
a methoxymethylated butoxymethylated benzoguanamine, Cymel 1128 as
a butoxymethylated benzoguanamine and Cymel 1125-80 as a
methoxymethylated ethoxymethylated benzoguanamine containing
carboxyl groups as preferable ones. A benzoguanamine compound and a
benzoguanamine oligomer sold under a trade names of SB-201 and
BX-55H, respectively, (each a product by Sanwa Chemical Co.) are
also suitable as the component (A1).
[0031] The above described benzoguanamine compounds and oligomers
thereof can be used either singly or as a combination of two kinds
or more according to need.
[0032] The component (B) in the first embodiment of the inventive
undercoating composition is an inorganic acid or an organic acid of
which the acid residue contains a sulfur atom. The
sulfur-containing inorganic acid is exemplified by sulfuric acid,
sulfurous acid and thiosulfuric acid. The sulfur-containing organic
acid is exemplified by organic sulfonic acids. Esters of sulfuric
acid and sulfurous acid can also be used as the component (B). The
component (B) is preferably an organic sulfonic acid represented by
the general formula
R.sup.5--SO.sub.3H, (II)
[0033] in which R.sup.5 is an unsubstituted or substituted
monovalent hydrocarbon group. The monovalent hydrocarbon group
denoted by R.sup.5, which can be either saturated or unsaturated
and can be straightly linear, branched or cyclic, preferably has 1
to 20 carbon atoms. When the hydrocarbon group is a substituted
hydrocarbon group having one or more of substituents, the
substituent is exemplified by atoms of a halogen such as fluorine,
sulfonic acid group, carboxyl group, hydroxyl group, amino group
and cyano group.
[0034] The monovalent hydrocarbon group as R.sup.5 can be an
aromatic hydrocarbon group such as phenyl, naphthyl and anthryl
groups, of which phenyl group is particularly preferable. The
aromatic hydrocarbon group can optionally be substituted on the
aromatic ring structure by an aliphatic group having 1 to 20 carbon
atoms which can be saturated or unsaturated or can be straightly
linear, branched or cyclic. Besides the aliphatic hydrocarbon
groups as the substituent, the aromatic ring structure can be
substituted by other substituents such as halogen atoms, e.g.,
fluorine atoms, sulfonic acid groups, carboxyl groups, hydroxyl
groups, amino groups and cyano groups.
[0035] Examples of a particularly preferable organic sulfonic acid
as the component (B) include nonafluorobutane sulfonic acid,
methanesulfonic acid, dodecylbenzene sulfonic acid and
trifluoromethane sulfonic acid in respect of the effect of
improvement on the cross sectional profile of the patterned resist
layer formed on the undercoating layer. These organic sulfonic
acids can be used either singly or as a combination of two kinds or
more.
[0036] The amount of the above described acid as the component (B)
in the inventive undercoating composition according to the first
embodiment is in the range from 0.1 to 10 parts by weight or,
preferably, from 1 to 8 parts by weight per 100 parts by weight of
the component (A1).
[0037] The inventive undercoating composition is prepared by
dissolving the above described components (A1) and (B) as well as
other optional ingredients in an organic solvent as the component
(C) which is not particularly limitative provided that a uniform
solution can be obtained therewith. Examples of suitable organic
solvents include ketones such as acetone, methyl ethyl ketone,
cyclopentanone, cyclohexanone, methyl isoamyl ketone, 2-heptanone
and 1,1,1-trimethyl acetone, polyhydric alcohols and derivatives
thereof such as ethyleneglycol, ethyleneglycol monoacetate,
diethyleneglycol, diethyleneglycol monoacetate, propyleneglycol and
propyleneglycol monoacetate as well as monomethyl, monoethyl,
monopropyl, monobutyl and monophenyl ethers thereof, cyclic ethers
such as dioxane and esters such as ethyl lactate, methyl acetate,
ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate,
methyl 3-methoxypropionate and ethyl 3-ethoxypropionate. These
organic solvents can be used either singly or as a mixture of two
kinds or more.
[0038] Though not particularly limitative, the amount of the
organic solvent as the component (C) is preferably such that the
resultant solution contains the components (A1) and (B) in a total
concentration in the range from 5 to 20% by weight.
[0039] It is optional according to need that the inventive
undercoating composition is admixed with a surface active agent in
an amount up to 2000 ppm by weight relative to the solid content in
the solution with an object for improvement of the coating
workability of the solution and prevention of striation. Several
commercial products of fluorine-containing surface active agents
are particularly suitable for this purpose including Surflons
SC-103 and SR-100 (each a product by Asahi Glass Co.), EF-351 (a
product by Tohoku Hiryou Co.) and Fluorads Fc-431, Fc-135, Fc-98,
Fc-430 and Fc-176 (each a product by Sumitomo 3M Co.).
[0040] The undercoating composition of the present invention
according to the second embodiment comprises, in addition to the
essential components (A), (B1) and (C), a light-absorbing compound
as the component (D).
[0041] The component (A) is a nitrogen-containing organic compound
having at least two amino groups substituted by hydroxyalkyl and/or
alkoxyalkyl groups. Examples of suitable nitrogen-containing
organic compounds, which should be substituted by hydroxyalkyl
and/or alkoxyalkyl groups for the hydrogen atoms on the amino
groups, include melamine, urea, guanamine, acetoguanamine,
benzoguanamine, glycoluril, succinyl amide and ethyleneurea. The
substitution reaction can be performed according to a conventional
method by reacting these compounds in boiling water with
formaldehyde to effect methylolation followed, if necessary, by an
alkoxylation reaction of the methylolated compound with a lower
alcohol such as methyl, ethyl, propyl, isopropyl, n-butyl and
isobutyl alcohols.
[0042] Among the above described compounds suitable as the
component (A), particularly preferable are those derived from
melamine, benzoguanamine or glycoluril or, more preferably, from a
triazine compound such as melamine and benzoguanamine or, most
preferably, from a triazine compound by methoxymethylation.
[0043] The melamine derivatives and benzoguanamine derivatives can
be in the form of an oligomer such as a dimer or trimer. The degree
of substitution for the amino-hydrogen atoms therein is preferably
such that each triazine ring on an average has at least 3 but less
than 6 methylol groups or alkoxymethyl groups.
[0044] A variety of commercial products available on the market can
be used as the component (A) including, in addition to the Cymel
products (each a product by Mitsui Cyanamid Co.) given as the
examples of the component (A1) in the first embodiment, MX-750
having 3.7 methoxymethyl groups on an average per triazine ring and
MW-30 having 5.8 methoxymethyl groups on an average per triazine
ring (each a product by Sanwa Chemical Co.), Cymels 300, 301, 303,
350, 370, 771, 325, 327, 703 and 712 each as a methoxymethylated
melamine, Cymels 235, 236, 238, 212, 253 and 254 each as a
methoxymethylated butoxymethylated melamine, Cymels 506 and 508
each as a butoxymethylated melamine, Cymel 1141 as a
methoxymethylated isobutoxymethylated melamine containing carboxyl
groups, Cymel 1170 as a butoxymethylated glycoluril and Cymel 1172
as a methylolated glycoluril. These nitrogen-containing compounds
can be used either singly or as a mixture of two kinds or more
according to need.
[0045] When the patternwise exposure of the photoresist layer is
performed by using KrF excimer laser beams having a wavelength of
about 248 nm, the component (A) is selected preferably from the
benzoguanamine derivatives among the above named commercial
products including Cymels 1123, 1123-10, 1128 and 1125-80 in
respect of the low transmissivity to the laser beams of the
wavelength. Cymel 1125-80 is more preferable as a methoxymethylated
ethoxymethylated benzoguanamine having carboxyl groups.
[0046] The component (B1) in this second embodiment is preferably
an organic acid selected from the group consisting of aliphatic
carboxylic and sulfonic acids and alkylbenzene carboxylic and
sulfonic acids, of which a part of the hydrogen atoms in the acid
residue are substituted by fluorine atoms.
[0047] The above mentioned aliphatic carboxylic or sulfonic acid is
represented by the general formula
R.sup.6--M, (III)
[0048] in which R.sup.6 is a fluorine-substituted, saturated or
unsaturated aliphatic hydrocarbon group or, preferably, alkyl group
having 1 to 20 carbon atoms and X is a carboxylic group --COOH or
sulfonic acid group --SO.sub.3H. The structure of the aliphatic
hydrocarbon group denoted by R.sup.6 can be straightly linear,
branched or cyclic and can optionally be substituted by one or more
of sulfonic acid groups, carboxyl groups, hydroxyl groups, amino
groups and/or cyano groups.
[0049] On the other hand, the alkylbenzene carboxylic or sulfonic
acid as a class of the acids suitable as the component (B1) is
represented by the general formula 2
[0050] in which X has the same meaning as defined for the formula
(III) given above and at least one of the two R.sup.7 groups is a
fluorine-substituted alkyl group defined in the same way as for
R.sup.6 in the formula (III), the rest, if any, being a hydrogen
atom.
[0051] Examples of fluorine-substituted organic acids preferably
used as the component (B1) in the second embodiment include
trifluoromethane sulfonic acid, pentafluoroethane sulfonic acid,
heptafluoropropane sulfonic acid, nonafluorobutane sulfonic acid,
trifluoroacetic acid, pentafluoropropionic acid, heptafluorobutyric
acid, nonafluorovaleric acid, 4-(trifluoromethyl)benzene sulfonic
acid, 4-(trifluoroethyl)-benzen- e sulfonic acid,
perfluorododecylbenzene sulfonic acid, 1,2-(tetrafluoroethane)
disulfonic acid, tetrafluoroisethionic acid, difluorosulfoacetic
acid and tetrafluorotaurine NH.sub.2--CF.sub.2--CF.su-
b.2--SO.sub.3H, of which trifluoromethane sulfonic acid and
nonafluorobutane sulfonic acid are particularly preferable in
respect of the improving effect on the cross sectional profile of
the patterned resist layer at the base part.
[0052] The above named various fluorine-containing organic acids as
the component (B1) can be used either singly or as a combination of
two kinds or more. The amount of the component (B1) in the
inventive undercoating composition according to the second
embodiment is selected usually in the range from 0.1 to 10 parts by
weight or, preferably, from 1 to 8 parts by weight per 100 parts by
weight of the component (A) though dependent on the types of the
acid.
[0053] In addition to the above described components (A) and (B1)
as well as the component (C) which is an organic solvent selected
from the same classes of organic solvents exemplified previously in
connection with the first embodiment of the invention, the
undercoating composition according to this second embodiment
further comprises the component (D) which is a light-absorbing
compound which should have high absorptivity to the light used for
the patternwise light-exposure of the photoresist layer provided on
the undercoating layer within the characteristic wavelength region
of the photosensitivity of the resist so as to prevent the adverse
influences by the standing waves of the reflecting light at the
substrate surface or irregular reflection of the light at the
stepped level difference on the substrate surface.
[0054] Organic compounds of various classes can be used for the
purpose including salicylate compounds, benzophenone compounds,
benzotriazole compounds, cyanoacrylate compounds, azo compounds,
polyene compounds, anthraquinone compounds, bisphenyl sulfone
compounds, bisphenyl sulfoxide compounds and anthracene compounds
although any of these compounds can be used either singly or as a
combination of two kinds or more.
[0055] Preferable among the above named various types of compounds
as the component (D) in respect of good miscibility with the
component (A) or solubility in the organic solvent as the component
(C), suppression of intermixing between layers and reaction
promoting activity for the thermal crosslinking of the component
(A) are those belonging to the classes of benzophenone compounds,
bisphenylsulfone compounds, bisphenyl sulfoxide compounds or
anthracene compounds or, more preferably, polyhydroxy compounds
including polyhydroxy-benzophenone compounds, i.e. benzophenone
compounds having at least two hydroxyl groups in a molecule,
bisphenyl sulfone compounds having at least two hydroxyl groups in
a molecule, bisphenyl sulfoxide compounds having at least two
hydroxyl groups in a molecule or anthracene compounds having at
least one hydroxyl or hydroxyalkyl group in a molecule. The
anthracene compounds are the most preferable among the above named
classes of the compounds although any of them can be used either
singly or as a combination of two kinds or more.
[0056] Examples of the polyhydroxybenzophenone compounds include
2,4-dihydroxy benzophenone, 2,3,4-trihydroxy benzophenone,
2,2',4,4'-tetrahydroxy benzophenone, 2,2',5,6'-tetrahydroxy
benzophenone, 2,2'-dihydroxy-4-methoxy benzophenone,
2,6-dihydroxy-4-methoxy benzophenone, 2,2'-dihydroxy-4,4'-dimethoxy
benzophenone, 4-dimethylamino-2',4'-dihydroxy benzophenone and
4-dimethylamino-3',4'-di- hydroxy benzophenone.
[0057] Examples of the polyhydroxy bisphenyl sulfone and sulfoxide
compounds include bis(hydroxyphenyl) sulfone and sulfoxide
compounds and bis(polyhydroxyphenyl) sulfone and sulfoxide
compounds exemplified by bis(4-hydroxyphenyl) sulfone,
bis(3,5-dimethyl-4-hydroxyphenyl) sulfone, bis(2,3-dihydroxyphenyl)
sulfone, bis(5-chloro-2,3-dihydroxyphenyl) sulfone,
bis(2,4-dihydroxyphenyl) sulfone, bis(2,4-dihydroxy-6-methylphen-
yl) sulfone, bis(5-chloro-2,4-dihydroxyphenyl) sulfone,
bis(2,5-dihydroxyphenyl) sulfone, bis(3,4-dihydroxyphenyl) sulfone,
bis(3,5-dihydroxyphenyl) sulfone, bis(2,3,4-trihydroxyphenyl)
sulfone, bis(2,3,4-trihydroxy-6-methylphenyl) sulfone,
bis(5-chloro-2,3,4-trihydro- xyphenyl) sulfone,
bis(2,4,6-trihydroxyphenyl) sulfone,
bis(5-chloro-2,4,6-trihydroxyphenyl) sulfone, bis(4-hydroxyphenyl)
sulfoxide, bis(3,5-dimethyl-4-hydroxyphenyl) sulfoxide,
bis(2,3-dihydroxyphenyl) sulfoxide,
bis(5-chloro-2,3-dihydroxyphenyl) sulfoxide,
bis(2,4-dihydroxyphenyl) sulfoxide, bis(2,4-dihydroxy-6-methyl-
phenyl) sulfoxide, bis(5-chloro-2,4-dihydroxyphenyl) sulfoxide,
bis(2,5-dihydroxyphenyl) sulfoxide, bis(3,4-dihydroxyphenyl)
sulfoxide, bis(3,5-dihydroxyphenyl) sulfoxide,
bis(2,3,4-trihydroxyphenyl) sulfoxide,
bis(2,3,4-trihydroxy-6-methylphenyl) sulfoxide,
bis(5-chloro-2,3,4-trihydroxyphenyl) sulfoxide,
bis(2,4,6-trihydroxypheny- l) sulfoxide and
bis(5-chloro-2,4,6-trihydroxyphenyl) sulfoxide.
[0058] The anthracene compound having at least one hydroxyl or
hydroxyalkyl group in a molecule should have a condensed ring
structure of anthracene substituted by substituents thermally
crosslinkable with the component (A). Such an anthracene compound
is represented by the general formula 3
[0059] in which the subscript n is a positive integer of 1 to 10,
the subscript m is 0 or a positive integer not exceeding 8 and the
subscript 1 is 0 or a positive integer not exceeding 6 with the
proviso that at least either one of m and l is not 0.
[0060] Particular examples of the anthracene compounds preferable
as the component (D) include 1-hydroxy anthracene, 9-hydroxy
anthracene, 1,2-dihydroxy anthracene, 1,5-dihydroxy anthracene,
9,10-dihydroxy anthracene, 1,2,3-trihydroxy anthracene,
1,2,3,4-tetrahydroxy anthracene, 1,2,3,4,5,6-hexahydroxy
anthracene, 1,2,3,4,5,6,7,8-octahydroxy anthracene, 1-hydroxymethyl
anthracene, 9-hydroxymethyl anthracene, 9-hydroxyethyl anthracene,
9-hydroxyhexyl anthracene, 9-hydroxyoctyl anthracene and
9,10-di(hydroxymethyl) anthracene.
[0061] Besides the anthracene compounds represented by the general
formula (V), anthracene carboxylic acids or, in particular,
9-anthracene carboxylic acid, can be used suitably.
[0062] Among the above named anthracene compounds, 9-hydroxymethyl
anthracene and 9-anthracene carboxylic acid are particularly
preferable in respect of high light absorptivity in addition to the
good thermal crosslinkability and high effectiveness for prevention
of intermixing of layers.
[0063] The amount of the light-absorbing compound as the component
(D) in the inventive undercoating composition according to the
second embodiment of the invention is in the range from 5 to 70% by
weight or, preferably, from 10 to 60% by weight based on the total
amount of the components (A), (B1) and (D).
[0064] The inventive undercoating composition according to the
third embodiment of the invention comprises, as the essential
ingredients, the components (A), (B2), (C) and (D), of which the
components (A), (C) and (D) can be the same ones as those described
above for the second embodiment. The third embodiment is
characterized by the use of a specific acid as the component (B2),
which is selected from aliphatic carboxylic acids, aliphatic
sulfonic acids, alkylbenzene carboxylic acids, alkylbenzene
sulfonic acids and sulfur containing inorganic acids.
[0065] The aliphatic carboxylic or sulfonic acid is represented by
the general formula
R.sup.8--X, (VI)
[0066] in which R.sup.8 is a substituted or unsubstituted aliphatic
monovalent hydrocarbon group having 1 to 20 carbon atoms or, in
particular, alkyl group and X is a carboxyl group --COOH or
sulfonic acid group --SO.sub.3H. The alkylbenzene carboxylic or
sulfonic acid is represented by the general formula 4
[0067] in which X has the same meaning as defined above and at
least one of the two R.sup.9 groups is an alkyl group having 1 to
20 carbon atoms, which may be straightly linear, branched or cyclic
in structure, the rest, if any, being a hydrogen atom.
[0068] The sulfur-containing inorganic acid as the component (B2)
includes those of which the acid residue has a sulfur atom and an
oxygen atom exemplified by sulfuric acid, sulfurous acid and
thiosulfuric acid.
[0069] Among the above described various types of acid compounds,
aliphatic sulfonic acids, alkylbenzene sulfonic acids and sulfuric
acid are preferable and, in particular, methanesulfonic acid,
dodecylbenzene sulfonic acid and combinations thereof are more
preferable in respect of the high effectiveness for prevention of
irregularities in the cross sectional profile of the patterned
resist layer in the base part irrespective of the types of the
photoresist compositions forming the photoresist layer.
[0070] The above described various acid compounds as the component
(B2) can be used either singly or as a combination of two kinds or
more according to need. The amount of the component (B2) in the
undercoating composition according to the third embodiment is in
the range from 0.1 to 10 parts by weight or, preferably, from 1 to
8 parts by weight per 100 parts by weight of the component (A).
[0071] The above described undercoating composition for
photolithographic resist is applicable to the formation of an
undercoating layer intervening between the substrate surface and a
photoresist layer regardless of the types of the photoresist
composition forming the photoresist layer which may be
negative-working or positive-working provided that the photoresist
layer after patternwise light exposure is developable with an
aqueous alkaline solution as the developer. The positive-working
photoresist composition include those containing a naphthoquinone
diazide compound and a novolak resin, those containing an acid
generating agent capable of releasing an acid by exposure to light,
a compound having a group capable of increasing the solubility of
the compound in an aqueous alkaline solution by decomposition when
exposed to light and an alkali-soluble resin and those containing a
light-sensitive acid generating agent and an alkali-soluble resin
capable of being imparted with increased solubility in an aqueous
alkaline solution by decomposition in the presence of an acid. The
negative-working photoresist composition includes those containing
a light-sensitive acid generating agent, a crosslinking agent and
an alkali-soluble resin though not particularly limitative
thereto.
[0072] A typical procedure for the use of the inventive
undercoating composition in the photolithographic patterning works
is as follows. Thus, in the first place, the surface of a substrate
such as a silicon wafer is coated with the undercoating composition
in the form of a solution by using a suitable coating machine such
as a spinner followed by a heating treatment at a temperature of
100 to 300.degree. C. to give a dried undercoating layer having a
thickness in the range from 0.05 to 0.5 .mu.m. The undercoating
layer is insolubilized in an aqueous alkaline solution by the
crosslinking reaction as a result of the above mentioned heating
treatment.
[0073] In the next place, the undercoating layer is overcoated with
a photoresist solution by using a spinner followed by drying to
form a photoresist layer on the undercoating layer, which is then
patternwise exposed to actinic rays such as KrF or ArF excimer
laser beams on a suitable light-exposure machine such as a
minifying projection exposure machine through a photomask bearing a
desired pattern to form a latent image of the pattern. The
photoresist layer bearing the latent image is then developed by
using an aqueous alkaline developer solution such as a 1 to 10% by
weight aqueous solution of tetramethylammonium hydroxide to
dissolve away the resist layer in the light-exposed areas or in the
areas unexposed to light for the positive-working and
negative-working photoresist compositions, respectively, followed
by rinse with water and drying to give a patterned resist layer of
high fidelity to the photomask pattern.
[0074] By virtue of the undercoating layer interposed between the
substrate surface and the photoresist layer by using the inventive
undercoating composition, a patterned resist layer having an
excellently orthogonal cross sectional profile can be obtained
without occurrence of irregularities such as trailing skirts and
notchings in the base part of the cross section even by using
actinic rays of short wavelengths such as excimer laser beams,
X-rays and electron beams with an object to accomplish further
increased fineness of patterning.
[0075] In the following, the undercoating composition of the
present invention is described in more detail by way of Examples
and Comparative Examples which, however, never limit the scope of
the invention in any way.
EXAMPLE 1
[0076] An undercoating solution was prepared by dissolving 100 g of
Cymel 1125-80 (supra) and 5 g of dodecylbenzene sulfonic acid in
950 g of propyleneglycol monomethyl ether.
[0077] Several semiconductor silicon wafers were coated each with
the above prepared undercoating solution on a spinner followed by a
drying treatment at 90.degree. C. for 90 seconds and then a heat
treatment at 180.degree. C. for 5 minutes to form an undercoating
layer having a thickness of 100 nm.
[0078] In the next place, a photoresist layer was formed on the
undercoating layer by using a chemical-amplification
positive-working photoresist solution TDUR-DP604 or TDUR-P034 or a
chemical-amplification negative-working photoresist solution
TDUR-N908 (each a product by Tokyo Ohka Kogyo Co.) on each of the
silicon wafers having the undercoating layer.
[0079] Thereafter, the photoresist layer on the respective silicon
wafers with intervention of an undercoating layer was patternwise
exposed to light on a minifying projection exposure machine Nikon
NSR-2005EX8A (manufactured by Nikon Co.) through a pattern-bearing
photomask followed by a post-exposure baking treatment on a hot
plate at 130.degree. C. for 90 seconds and then a development
treatment with a 2.38% by weight aqueous solution of
tetramethylammonium hydroxide, rinse with water and drying to give
a patterned resist layer on the silicon wafer.
[0080] The thus obtained patterned resist layer was examined on a
scanning electron microscopic photograph for the cross sectional
profile of the patterned resist layer to find that all of the
line-patterned resist layers had an orthogonal cross sectional
profile standing upright on the silicon wafer surface without any
irregularities.
EXAMPLE 2
[0081] The experimental procedure was substantially the same as in
Example 1 excepting for the replacement of dodecylbenzene sultonic
acid in the undercoating solution with the same amount of
methanesulfonic acid.
[0082] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layers
were that each of the profiles had vertical side lines in the base
part.
EXAMPLE 3
[0083] The experimental procedure was substantially the same as in
Example 1 excepting for the replacement of dodecylbenzene sulfonic
acid in the undercoating solution with the same amount of
nonafluorobutane sulfonic acid.
[0084] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layers
were that each of the profiles had vertical side lines in the base
part.
EXAMPLE 4
[0085] The experimental procedure was substantially the same as in
Example 1 except that 5 g of dodecylbenzene sulfonic acid in the
undercoating solution were replaced with 3.5 g of benzene sulfonic
acid monohydrate and the photoresist composition was limited to the
chemical-amplification positive-working photoresist compositions
TDUR-DP604 and TDUR-PO34.
[0086] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layers
were that each of the profiles had vertical side lines in the base
part.
EXAMPLE 5
[0087] The experimental procedure was substantially the same as in
Example 1 excepting that 5 g of dodecylbenzene sulfonic acid in the
undercoating solution were replaced with 3.5 g of 2-naphthalene
sulfonic acid monohydrate and the photoresist composition was
limited to the chemical-amplification positive-working photoresist
composition TDUR-P034.
[0088] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layer
were that the cross sectional profile had vertical side lines in
the base part.
EXAMPLE 6
[0089] The experimental procedure was substantially the same as in
Example 1 except that 5 g of dodecylbenzene sulfonic acid in the
undercoating solution were replaced with 3.5 g of 1,2-ethane
disulfonic acid and the photoresist composition was limited to the
chemical-amplification positive-working photoresist composition
TDUR-DP604.
[0090] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layer
were that the profile had vertical side lines in the base part.
EXAMPLE 7
[0091] The experimental procedure was substantially the same as in
Example 1 except that 5 g of dodecylbenzene sulfonic acid in the
undercoating solution were replaced with 3.5 g of sulfuric acid and
the photoresist composition was limited to the
chemical-amplification positive-working photoresist composition
TDUR-DP604.
[0092] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layer
were that the profile had vertical side lines in the base part.
COMPARATIVE EXAMPLE 1
[0093] An undercoating solution was prepared by dissolving 60 g of
bis(4-hydroxyphenyl) sulfone and 60 g of Cymel 1125-80 (supra) in
1200 g of propyleneglycol monomethyl ether.
[0094] Several semiconductor silicon wafers were coated each with
the above prepared undercoating solution on a spinner followed by a
drying treatment at 90.degree. C. for 90 seconds and then a heat
treatment at 180.degree. C. for 90 seconds to form an undercoating
layer having a thickness of 100 nm.
[0095] In the next place, a photoresist layer was formed on the
undercoating layer by using a chemical-amplification
positive-working photoresist solution TDUR-DP604 or TDUR-P034 or a
chemical-amplification negative-working photoresist solution
TDUR-N908 (each a product by Tokyo Ohka Kogyo Co.) on each of the
silicon wafers having the undercoating layer.
[0096] Thereafter, the photoresist layer on the respective silicon
wafers was patternwise exposed to light on a minifying projection
exposure machine Nikon NSR-2005EX8A (manufactured by Nikon Co.)
through a pattern-bearing photomask followed by a post-exposure
baking treatment on a hot plate at 130.degree. C. for 90 seconds
and then a development treatment with a 2.38% by weight aqueous
solution of tetramethylammonium hydroxide, rinse with water and
drying to give a patterned resist layer on the silicon wafer.
[0097] The thus obtained patterned resist layers were examined on a
scanning electron microscopic photograph for the cross sectional
profile of the patterned resist layer to find occurrence of
trailing skirts in the base part of the patterned resist layers
obtained by using the positive-working photoresist solutions and
notchings in the base part of the patterned resist layer obtained
by using the negative-working photoresist solution.
COMPARATIVE EXAMPLE 2
[0098] The experimental procedure was substantially the same as in
Comparative Example 1 except that the undercoating solution was
prepared by dissolving 100 g of hexamethoxymethyl melamine and 5 g
of dodecylbenzene sulfonic acid in 950 g of propyleneglycol
monomethyl ether.
[0099] The cross sectional profile of the patterned resist layer
was examined on a scanning electron microscopic photograph to find
that a patterned resist layer having the target line width could
not be obtained due to the great influences of standing waves.
EXAMPLE 8
[0100] An undercoating solution was prepared by dissolving 1 g of
BX-55H (a product by Sanwa Chemical Co.) and 0.1 g of
trifluoromethane sulfonic acid in 24 g of propyleneglycol
monomethyl ether.
[0101] A silicon wafer was coated on a spinner with the above
prepared undercoating solution followed by a heat treatment at
150.degree. C. for 90 seconds to form an undercoating layer having
a thickness of 100 nm. Further, a photoresist layer was formed on
the above formed undercoating layer with a chemical-amplification
positive-working photoresist solution (TArF 6a-37, a product by
Tokyo Ohka Kogyo Co.).
[0102] The photoresist layer was patternwise exposed to ArF excimer
laser beams on an ArF light-exposure machine followed by a
post-exposure baking treatment on a hot plate at 110.degree. C. for
90 seconds and then subjected to a development treatment with a
2.38% by weight aqueous solution of tetramethylammonium hydroxide
followed by rinse with water and drying to give a patterned resist
layer.
[0103] With this patterned resist layer as an etching mask, an
etching treatment was undertaken in an etching apparatus (OAPM-406,
manufactured by Tokyo Ohka Kogyo Co.) using a 95:5 mixture of
carbon tetrafluoride and oxygen as the etching gas under a pressure
of 200 mTorr at a stage temperature of 20 .degree. C. and a
high-frequency output of 300 watts to measure the etching rates of
the resist layer and the undercoating layer, which were 44.7
nm/minute and 81.4 nm/minute, respectively, corresponding to a
selectivity ratio of 81.4/44.7=1.82.
EXAMPLE 9
[0104] An undercoating solution was prepared by dissolving 100 g of
Cymel 1125-80 (supra), 3.5 g of nonafluorobutane sulfonic acid and
100 g of bis(4-hydroxyphenyl) sulfone in 2500 g of propyleneglycol
monomethyl ether.
[0105] Several semiconductor silicon wafers were coated each with
the above prepared undercoating solution on a spinner followed by a
drying treatment at 90.degree. C. for 90 seconds and then a heat
treatment at 180.degree. C. for 5 minutes to form an undercoating
layer having a thickness of 100 nm.
[0106] In the next place, a photoresist layer was formed on the
undercoating layer by using a chemical-amplification
positive-working photoresist solution TDUR-DP604 or TDUR-P034 or a
chemical-amplification negative-working photoresist solution
TDUR-N908 (each a product by Tokyo Ohka Kogyo Co.) on each of the
silicon wafers.
[0107] Thereafter, the photoresist layer on the respective silicon
wafers was patternwise exposed to light on a minifying projection
exposure machine Nikon NSR-2005EX8A (manufactured by Nikon Co.)
through a pattern-bearing photomask followed by a post-exposure
baking treatment on a hot plate at 130.degree. C. for 90 seconds
and then a development treatment with a 2.38% by weight aqueous
solution of tetramethylammonium hydroxide, rinse with water and
drying to give a patterned resist layer on the silicon wafer.
[0108] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layers
were that all of the line-patterned resist layers had an orthogonal
cross sectional profile standing upright on the substrate
surface.
EXAMPLE 10
[0109] The experimental procedure was substantially the same as in
Example 9 except that nonafluorobutane sulfonic acid in the
undercoating solution was replaced with the same amount of
nonafluorovaleric acid and the photoresist composition was limited
to the chemical-amplification positive-working photoresist
compositions TDUR-DP604 and TDUR-P034.
[0110] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layers
were that each of the patterned resist layers had a vertical cross
sectional profile in the base part.
EXAMPLE 11
[0111] The experimental procedure was substantially the same as in
Example 9 except that nonafluorobutane sulfonic acid in the
undercoating solution was replaced with the same amount of
trifluoroacetic acid and the photoresist composition was limited to
the chemical-amplification positive-working photoresist composition
TDUR-DP604.
[0112] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layer
were that the patterned resist layer had a vertical cross sectional
profile in the base part.
EXAMPLE 12
[0113] The experimental procedure was substantially the same as in
Example 9 except that nonafluorobutane sulfonic acid in the
undercoating solution was replaced with the same amount of
trifluoromethane sulfonic acid and the photoresist composition was
limited to the chemical-amplification positive-working photoresist
composition TDUR-DP604.
[0114] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layer
were that the patterned resist layer had a vertical cross sectional
profile in the base part.
EXAMPLE 13
[0115] The experimental procedure was substantially the same as in
Example 9 except that the undercoating solution was prepared by
dissolving 50 g of Cymel 1125-80 (supra), 3.5 g of nonafluorobutane
sulfonic acid and 50 g of 9-hydroxymethyl anthracene in 2000 g of
propyleneglycol monomethyl ether.
[0116] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layers
were that all of the patterned resist layers each had a vertical
cross sectional profile in the base part.
COMPARATIVE EXAMPLE 3
[0117] An undercoating solution was prepared by dissolving 60 g of
Cymel 1125-80 (supra) and 60 g of bis(4-hydroxyphenyl) sulfone in
1200 g of propyleneglycol monomethyl ether.
[0118] Several semiconductor silicon wafers were coated each with
the above prepared undercoating solution on a spinner followed by a
drying treatment at 90.degree. C. for 90 seconds and then a heat
treatment at 180.degree. C. for 90 seconds to form an undercoating
layer having a thickness of 100 nm.
[0119] In the next place, a photoresist layer was formed on the
undercoating layer by using a chemical-amplification
positive-working photoresist solution TDUR-DP604 or TDUR-P034
(supra) or a chemical-amplification negative-working photoresist
solution TDUR-N908 (supra) on each of the silicon wafers having the
undercoating layer.
[0120] Thereafter, the photoresist layer on the respective silicon
wafers was patternwise exposed to light on a minifying projection
exposure machine Nikon NSR-2005EX8A (manufactured by Nikon Co.)
through a pattern-bearing photomask followed by a post-exposure
baking treatment on a hot plate at 130.degree. C. for 90 seconds
and then a development treatment with a 2.38% by weight aqueous
solution of tetramethylammonium hydroxide, rinse with water and
drying to give a patterned resist layer on the silicon wafer.
[0121] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layers
were that trailing skirts were found when the photoresist
composition was positive-working and notchings were found in the
base part when the photoresist composition was
negative-working.
EXAMPLE 14
[0122] An undercoating solution was prepared by dissolving 60 g of
Cymel 1125-80 (supra), 3.5 g of dodecylbenzene sulfonic acid and 60
g of bis(4-hydroxyphenyl) sulfone in 1300 g of propyleneglycol
monomethyl ether.
[0123] Several semiconductor silicon wafers were coated each with
the above prepared undercoating solution on a spinner followed by a
drying treatment at 90.degree. C. for 90 seconds and then a heat
treatment at 180.degree. C. for 90 seconds to form an undercoating
layer having a thickness of 100 nm.
[0124] In the next place, a photoresist layer was formed on the
undercoating layer by using a chemical-amplification
positive-working photoresist solution TDUR-DP604 or TDUR-P034 or a
chemical-amplification negative-working photoresist solution
TDUR-N908 (each a product by Tokyo Ohka Kogyo Co.) on each of the
silicon wafers having the undercoating layer.
[0125] Thereafter, the photoresist layer on the respective silicon
wafers was patternwise exposed to light on a minifying projection
exposure machine Nikon NSR-2005EX8A (manufactured by Nikon Co.)
through a pattern-bearing photomask followed by a post-exposure
baking treatment on a hot plate at 130.degree. C. for 90 seconds
and then a development treatment with a 2.38% by weight aqueous
solution of tetramethylammonium hydroxide, rinse with water and
drying to give a patterned resist layer on the silicon wafer.
[0126] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layers
were that all of the line-patterned resist layers had an orthogonal
cross sectional profile standing upright on the substrate
surface.
EXAMPLE 15
[0127] The experimental procedure was substantially the same as in
Example 14 excepting for the replacement of dodecylbenzene sulfonic
acid in the undercoating solution with the same amount of
methanesulfonic acid.
[0128] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layers
were that each of the patterned resist layers had a vertical cross
sectional profile in the base part.
EXAMPLE 16
[0129] The experimental procedure was substantially the same as in
Example 14 excepting for the replacement of dodecylbenzene sulfonic
acid in the undercoating solution with the same amount of sulfuric
acid.
[0130] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layers
were that each of the patterned resist layers had a vertical cross
sectional profile in the base part.
EXAMPLE 17
[0131] The experimental procedure was substantially the same as in
Example 14 except that the undercoating solution was prepared by
dissolving 50 g of Cymel 1125-80 (supra), 5 g of dodecylbenzene
sulfonic acid and 50 g of 9-hydroxymethyl anthracene in 2000 g of
propyleneglycol monomethyl ether.
[0132] The results of the scanning electron microscopic examination
of the cross sectional profile of the line-patterned resist layers
were that all of the patterned resist layers each had a vertical
cross sectional profile in the base part.
* * * * *