U.S. patent application number 09/791619 was filed with the patent office on 2002-07-04 for composition for film formation, method of film formation, and silica-based film.
This patent application is currently assigned to JSR CORPORATION. Invention is credited to Hasegawa, Kouichi, Hayashi, Eiji, Youngsoo, Seo.
Application Number | 20020086167 09/791619 |
Document ID | / |
Family ID | 26586214 |
Filed Date | 2002-07-04 |
United States Patent
Application |
20020086167 |
Kind Code |
A1 |
Hayashi, Eiji ; et
al. |
July 4, 2002 |
Composition for film formation, method of film formation, and
silica-based film
Abstract
A composition for film formation which is capable of giving a
silica-based coating film having an exceeding low dielectric
constant and improved mechanical strength and useful as an
interlayer insulating film in semiconductor devices and the like, a
process for producing the composition, and a silica-based film
obtained from the composition. The composition comprises (A) a
product of hydrolysis and condensation obtained by hydrolyzing and
condensing one or more silane compounds, and (B) an organic
solvent.
Inventors: |
Hayashi, Eiji; (Ibaraki,
JP) ; Hasegawa, Kouichi; (Ibaraki, JP) ;
Youngsoo, Seo; (Chungchongnam-Do, KR) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Assignee: |
JSR CORPORATION
Tokyo
JP
|
Family ID: |
26586214 |
Appl. No.: |
09/791619 |
Filed: |
February 26, 2001 |
Current U.S.
Class: |
428/447 ;
257/E21.261; 528/10 |
Current CPC
Class: |
H01L 21/3122 20130101;
H01L 21/02282 20130101; C09D 183/04 20130101; Y10T 428/31663
20150401; H01L 21/02216 20130101; H01L 21/02126 20130101; C09D
183/04 20130101; C08L 2666/36 20130101 |
Class at
Publication: |
428/447 ;
528/10 |
International
Class: |
B32B 009/04; C08G
077/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2000 |
JP |
P. 2000-051136 |
Apr 10, 2000 |
JP |
P. 2000-108307 |
Claims
What is claimed is:
1. A composition for film formation which comprises: (A) a product
of hydrolysis and condensation obtained by hydrolyzing and
condensing one or more silane compounds selected from the group
consisting of compounds represented by the following formula (1),
compounds represented by the following formula (2), and compounds
represented by the following formula (3) in the presence of 0.2 mol
or more of an alkaline compound per mol of the silane
compounds,R.sub.aSi(OR.sup.1).sub.4-a (1)wherein R represents a
hydrogen atom, a fluorine atom, or a monovalent organic group;
R.sup.1 represents a monovalent organic group; and a Is an integer
of 1 or 2; Si(OR.sup.2).sub.4 (2)wherein R.sup.2 represents a
monovalent organic
group;R.sup.3.sub.b(R.sup.4O).sub.3-bSi--(R.sup.7).sub.d--Si(OR.sup.5).su-
b.3-cR.sup.6.sub.c (3)wherein R.sup.3 to R.sup.6 may be the same or
different and each represents a monovalent organic group; b and c
may be the same or different and each is a number of 0 to 2;
R.sup.7 represents an oxygen atom, a phenylene group, or a group
represented by --(CH.sub.2).sub.n--, wherein n is an integer of 1
to 6; and d is 0 or 1; and (B) an organic solvent.
2. The composition for film formation of claim 1, wherein the
alkaline compound is selected from the group consisting of ammonia
and organic amines.
3. The composition for film formation of claim 2, wherein the
organic amines are alkylamines, alkanolamines, and arylamines.
4. The composition for film formation of claim 1, wherein the
hydrolysis is conducted in the presence of from more than 20 mol to
150 mol of water per mol of the compounds represented by formulae
(1) to (3).
5. The composition for film formation of claim 1, wherein the
silane compounds comprise at least one compound represented by
formula (1) and at least one compound represented by formula
(2).
6. The composition for film formation of claim 1, which has a pH of
7 or lower.
7. A composition for film formation which comprises: (A) a product
of hydrolysis and condensation obtained by hydrolyzing and
condensing one or more silane compounds selected from the group
consisting of compounds represented by the following formula (1),
compounds represented by the following formula (2) , and compounds
represented by the following formula (3) in the presence of an
alkaline compound and from 20 to 150 mol of water per mol of the
silane compounds,R.sub.aSi(OR.sup.1).sub.4-a (1)wherein R
represents a hydrogen atom, a fluorine atom, or a monovalent
organic group; R.sup.1 represents a monovalent organic group; and a
Is an integer of 1 or 2; Si(OR.sup.2).sub.4 (2)wherein R.sup.2
represents a monovalent organic
group;R.sup.3.sub.b(R.sup.4O).sub.3-bSi--(R.sup.7).sub-
.d--Si(OR.sup.5).sub.3-cR.sup.6.sub.c (3)wherein R.sup.3 to
R.sup.6may be the same or different and each represents and then
heating the resultant coating.
10. A silica-based film obtained by the method of film formation of
claim 9.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a composition for film
formation. More particularly, the invention relates to a
composition for film formation which, when used as an interlayer
insulating film material in the production of semiconductor devices
and the like, can give a silica-based film excellent in dielectric
constant characteristics and mechanical strength.
BACKGROUND OF THE INVENTION
[0002] Silica (SiO.sub.2) films formed by vacuum processes such as
the CVD method have hitherto been used frequently as interlayer
insulating films in semiconductor devices and other devices. In
recent years, an insulating coating film which comprises a
tetraalkoxysilane hydrolyzate as the main component and is called
an SOG (spin on glass) film has come to be used for the purpose of
forming a more even interlayer insulating film. Furthermore, as a
result of the trend toward higher degree of integration in
semiconductor devices and the like, an interlayer insulating film
called an organic SOG film has been developed which comprises a
polyorganosiloxane as the main component and has a low dielectric
constant.
[0003] However, with further progress in the degree of integration
or multilayer constitution in semiconductor devices and the like,
better electrical insulation between conductors has come to be
required and, hence, an interlayer insulating film material having
a lower dielectric constant and excellent cracking resistance has
come to be desired.
[0004] Proposed as materials having a low dielectric constant are a
composition comprising a mixture of fine particles obtained by
condensing an alkoxysilane in the presence of ammonia and a basic
product of partial hydrolysis of an alkoxysilane (see JP-A-5-263045
(the term "JP-A" as used herein means an "unexamined published
Japanese patent application") and JP-A-5-315319) and a coating
fluid obtained by condensing a basic hydrolyzate of a
polyalkoxysilane in the presence of a mmonia (see JP-A-11-340219
and JP-A-11-340220). However, the materials obtained by these
methods each has a dielectric constant exceeding 2.5 and has hence
been insufficient for the progress of the degree of integration or
multilayer constitution in semiconductor devices and the like.
SUMMARY OF THE INVENTION
[0005] One object of the invention is to provide a composition for
film formation which eliminates the problem described above. More
particularly, the object is to provide a composition for film
formation which is capable of giving a silica-based coating film
having an exceeding low dielectric constant and improved mechanical
strength and useful as an interlayer insulating film in
semiconductor devices and the like.
[0006] Another object of the invention is to provide a process for
producing the composition.
[0007] Still another object of the invention is to provide a
silica-based film obtained from the composition.
[0008] The invention provides a composition for film formation
which comprises:
[0009] (A) a product of hydrolysis and condensation (hereinafter
referred to also as "product of hydrolysis and condensation (A)")
obtained by hydrolyzing and condensing one or more silane compounds
selected from the group consisting of compounds represented by the
following formula (1) (hereinafter referred to also as "compounds
(1)"), compounds represented by the following formula (2)
(hereinafter referred to also as "compounds (2)"), and compounds
represented by the following formula (3) (hereinafter referred to
also as "compounds (3)") in the presence of 0.2 mol or more of an
alkaline compound per mol of the silane compounds,
R.sub.aSi(OR.sup.1).sub.4-a (1)
[0010] wherein R represents a hydrogen atom, a fluorine atom, or a
monovalent organic group; R.sup.1 represents a monovalent organic
group; and a is an integer of 1 or 2;
Si(OR.sup.2).sub.4 (2)
[0011] wherein R.sup.2 represents a monovalent organic group;
R.sup.3.sub.b(R.sup.4O).sub.3-bSi--(R.sup.7).sub.d--Si(OR.sup.5).sub.3-cR.-
sup.6.sub.c (3)
[0012] wherein R.sup.3 to R.sup.6may be the same or different and
each represents a monovalent organic group; b and c may be the same
or different and each is a number of 0 to 2; R.sup.7 represents an
oxygen atom, a phenylene group, or a group represented by
--(CH.sub.2).sub.n--, wherein n is an integer of 1 to 6; and d is 0
or 1; and
[0013] (B) an organic solvent.
[0014] The invention further provides a method of film formation
which comprises applying the composition for film formation
described above to a substrate and then heating the resultant
coating.
[0015] The invention furthermore provides a silica-based film
obtained by the method of film formation described film.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The product of hydrolysis and condensation (A) in the
invention means a mixture of a hydrolyzate of at least one member
selected from the group consisting of the compounds (1) to (3) and
a condensate of the hydrolyzate, or means either of the hydrolyzate
and the condensate.
[0017] In the hydrolyzate in ingredient (A), all the R.sup.1O--,
R.sup.2O--, R.sup.4O--, and R.sup.5O-- groups contained in
compounds (1) to (3) to constitute ingredient (A) need not have
been hydrolyzed. For example, the hydrolyzate may be one in which
only one of those groups has been hydrolyzed or two or more thereof
have been hydrolyzed or may be a mixture of these.
[0018] The condensate in ingredient (A) means a product formed from
the hydrolyzate of compounds (1) to (3) to constitute ingredient
(A) by condensing silanol groups of the hydrolyzate to form
Si--O--Si bonds. In the invention, however, all the silanol groups
need not have undergone condensation. Namely, the term "condensate"
as used herein means a concept which includes, for example, a
condensate in which a slight proportion of the silanol groups have
been condensed and a mixture of condensates which differ in the
degree of condensation.
Product of Hydrolysis and Condensation (A)
[0019] The product of hydrolysis and condensation (A) is obtained
by hydrolyzing and condensing, in the presence of a specific amount
of an alkaline compound, at least one silane compound selected from
the group consisting of compounds (1) to (3).
[0020] Compounds (1):
[0021] Examples of the monovalent organic groups represented by R
and R.sup.1 in formula (1) include alkyl, aryl, allyl, and glycidyl
groups. In formula (1), R is preferably a monovalent organic group,
more preferably an alkyl or phenyl group.
[0022] The alkyl group preferably has 1 to 5 carbon atoms, and
examples thereof include methyl, ethyl, propyl, and butyl. These
alkyl groups may be linear or branched, and may be ones in which
one or more of the hydrogen atoms have been replaced, for example,
with fluorine atoms.
[0023] In formula (1), examples of the aryl group include phenyl,
naphthyl, methylphenyl, ethylphenyl, chlorophenyl, bromophenyl, and
fluorophenyl.
[0024] Specific examples of the compounds (1) include:
trimethoxysilane, triethoxysilane, tri-n-propoxysilane,
triisopropoxysilane, tri-n-butoxysilane, tri-sec-butoxysilane,
tri-tert-butoxysilane, triphenoxysilane, fluorotrimethoxysilane,
fluorotriethoxysilane, fluorotri-n-propoxysilane,
fluorotriisopropoxysilane, fluorotri-n-butoxysilane,
fluorotri-sec-butoxysilane, fluorotri-tert-butoxysilane, and
fluorotriphenoxysilane; methyltrimethoxysilane,
methyltriethoxysilane, methyltri-n-propoxysilane,
methyltri-iso-propoxysilane, methyltri-n-butoxysilane,
methyltri-sec-butoxysilane, methyltri-tert-butoxysilane,
methyltriphenoxysilane, ethyltrimethoxysilane,
ethyltriethoxysilane, ethyltri-n-propoxysilane,
ethyltri-iso-propoxysilane, ethyltri-n-butoxysilane,
ethyltri-sec-butoxysilane, ethyltri-tert-butoxysilane,
ethyltriphenoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane,
vinyltri-n-propoxysilane, vinyltri-iso-propoxysilan- e,
vinyltri-n-butoxysilane, vinyltri-sec-butoxysilane,
vinyltri-tert-butoxysilane, vinyltriphenoxysilane,
n-propyltrimethoxysilane, n-propyltriethoxysilane,
n-propyltri-n-propoxysilane, n-propyltriisopropoxysilane,
n-propyltri-n-butoxysilane, n-propyltri-sec-butoxysilane,
n-propyltri-tert-butoxysilane, n-propyltriphenoxysilane,
isopropyltrimethoxysilane, isopropyltriethoxysilane,
isopropyltri-n-propoxysilane, isopropyltriisopropoxysilane,
isopropyltri-n-butoxysilane, isopropyltri-sec-butoxysilane,
isopropyltri-tert-butoxysilane, isopropyltriphenoxysilane,
n-butyltrimethoxysilane, n-butyltriethoxysilane,
n-butyltri-n-propoxysila- ne, n-butyltriisopropoxysilane,
n-butyltri-n-butoxysilane, n-butyltri-sec-butoxysilane,
n-butyltri-tert-butoxysilane, n-butyltriphenoxysilane,
sec-butyltrimethoxysilane, sec-butyltriethoxysilane,
sec-butyltri-n-propoxysilane, sec-butyltriisopropoxysilane ,
sec-butyltri-n-butoxysilane, sec-butyltri-sec-butoxysilane,
sec-butyltri-tert-butoxysilane, sec-butyltriphenoxysilane,
tert-butyltrimethoxysilane, tert-butyltriethoxysilane,
tert-butyltri-n-propoxysilane, tert-butyltriisopropoxysilane,
tert-butyltri-n-butoxysilane, tert-butyltri-sec-butoxysilane,
tert-butyltri-tert-butoxysilane, tert-butyltriphenoxysilane,
phenyltrimethoxysilane, phenyltriethoxysilane,
phenyltri-n-propoxysilane, phenyltriisopropoxysila- ne,
phenyltri-n-butoxysilane, phenyltri-sec-butoxysilane,
phenyltri-tert-butoxysilane, phenyltriphenoxysilane,
.gamma.-aminopropyltrimethoxysilane,
.gamma.-aminopropyltriethoxysilane,
.gamma.-glycidoxypropyltrimethoxysilane,
.gamma.-glycidoxypropyltriethoxy- silane,
.gamma.-trifluoropropyltrimethoxysilane, and
.gamma.-trifluoropropyltriethoxysilane; and
dimethyldimethoxysilane, dimethyldiethoxysilane,
dimethyldi-n-propoxysilane, dimethyldiisopropoxysilane,
dimethyldi-n-butoxysilane, dimethyldi-sec-butoxysilane,
dimethyldi-tert-butoxysilane, dimethyldiphenoxysilane,
diethyldimethoxysilane, diethyldiethoxysilane,
diethyldi-n-propoxysilane, diethyldiisopropoxysilane,
diethyldi-n-butoxysilane, diethyldi-sec-butoxysilane,
diethyldi-tert-butoxysilane, diethyldiphenoxysilane,
di-n-propyldimethoxysilane, di-n-propyldiethoxysilane,
di-n-propyldi-n-propoxysilane, di-n-propyldiisopropoxysilane,
di-n-propyldi-n-butoxysilane, di-n-propyldi-sec-butoxysilane,
di-n-propyldi-tert-butoxysilane, di-n-propyldiphenoxysilane,
diisopropyldimethoxysilane, diisopropyldiethoxysilane,
diisopropyldi-n-propoxysilane, diisopropyldiisopropoxysilane,
diisopropyldi-n-butoxysilane, diisopropyldi-sec-butoxysilane,
diisopropyldi-tert-butoxysilane, diisopropyldiphenoxysilane,
di-n-butyldimethoxysilane, di-n-butyldiethoxysilane,
di-n-butyldi-n-propoxysilane, di-n-butyldiisopropoxysilane,
di-n-butyldi-n-butoxysilane, di-n-butyldi-sec-butoxysilane,
di-n-butyldi-tert-butoxysilane, di-n-butyldiphenoxysilane,
di-sec-butyldimethoxysilane, di-sec-butyldiethoxysilane,
di-sec-butyldi-n-propoxysilane, di-sec-butyldiisopropoxysilane,
di-sec-butyldi-n-butoxysilane, di-sec-butyldi-sec-butoxysilane,
di-sec-butyldi-tert-butoxysilane, di-sec-butyldiphenoxysilane,
di-tert-butyldimethoxysilane, di-tert-butyldiethoxysilane,
di-tert-butyldi-n-propoxysilane, di-tert-butyldiisopropoxysilane,
di-tert-butyldi-n-butoxysilane, di-tert-butyldi-sec-butoxysilane,
di-tert-butyldi-tert-butoxysilane, di-tert-butyldiphenoxysilane,
diphenyldimethoxysilane, diphenyldiethoxysilane,
diphenyldi-n-propoxysila- ne, diphenyldiisopropoxysilane,
diphenyldi-n-butoxysilane, diphenyldi-sec-butoxysilane,
diphenyldi-tert-butoxysilane, diphenyldiphenoxysilane, and
divinyltrimethoxysilane.
[0025] Preferred examples of the compounds (1) include
methyltrimethoxysilane, methyltriethoxysilane,
methyltri-n-propoxysilane, methyltriisopropoxysilane,
ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane,
vinyltriethoxysilane, phenyltrimethoxysilane,
phenyltriethoxysilane, dimethyldimethoxysilane,
dimethyldiethoxysilane, diethyldimethoxysilane,
diethyldiethoxysilane, diphenyldimethoxysilane, and
diphenyldiethoxysilane.
[0026] Those compounds may be used alone or as a mixture of two or
more thereof.
[0027] Compounds (2):
[0028] Examples of the monovalent organic group represented by
R.sup.2 in formula (2) include the same organic groups as those
enumerated above with regard to formula (1).
[0029] Examples of the compounds (2) include tetramethoxysilane,
tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane,
tetra-n-butoxysilane, tetra-sec-butoxysilane,
tetra-tert-butoxysilane, and tetraphenoxysilane.
[0030] Compounds (3):
[0031] Examples of the monovalent organic groups represented by
R.sup.3 to R.sup.6 in formula (3) include the same organic groups
as those enumerated above with regard to formula (1).
[0032] Examples of the compounds (3) wherein R.sup.7 in formula (3)
is an oxygen atom include hexamethoxydisiloxane,
hexaethoxydisiloxane, hexaphenoxydisiloxane,
1,1,1,3,3,-pentamethoxy-3-methyldisiloxane,
1,1,1,3,3-pentaethoxy-3-methyldisiloxane,
1,1,1,3,3-pentaphenoxy-3-methyl- disiloxane,
1,1,1,3,3-pentamethoxy-3-ethyldisiloxane,
1,1,1,3,3,-pentaethoxy-3-ethyldisiloxane,
1,1,1,3,3-pentaphenoxy-3-ethyld- isiloxane,
1,1,1,3,3-pentamethoxy-3-phenyldisiloxane,
1,1,1,3,3-pentaethoxy-3-phenyldisiloxane,
1,1,1,3,3,-pentaphenoxy-3-pheny- ldisiloxane,
1,1,3,3-tetramethoxy-1,3-dimethyldisiloxane,
1,1,3,3-tetraethoxy-1,3-dimethyldisiloxane,
1,1,3,3-tetraphenoxy-1,3-dime- thyldisiloxane,
1,1,3,3-tetramethoxy-1,3-diethyldisiloxane,
1,1,3,3-tetraethoxy-1,3-diethyldisiloxane,
1,1,3,3-tetraphenoxy-1,3-dieth- yldisiloxane,
1,1,3,3-tetramethoxy-1,3-diphenyldisiloxane,
1,1,3,3-tetraethoxy-1,3-diphenyldisiloxane,
1,1,3,3-tetraphenoxy-1,3-diph- enyldisiloxane,
1,1,3-trimethoxy-1,3,3-trimethyldisiloxane,
1,1,3-triethoxy-1,3,3-trimethyldisiloxane,
1,1,3-triphenoxy-1,3,3-trimeth- yldisiloxane,
1,1,3-trimethoxy-1,3,3-triethyldisiloxane,
1,1,3-triethoxy-1,3,3-triethyldisiloxane,
1,1,3-triphenoxy-1,3,3-triethyl- disiloxane,
1,1,3-trimethoxy-1,3,3-triphenyldisiloxane,
1,1,3-triethoxy-1,3,3-triphenyldisiloxane,
1,1,3-triphenoxy-1,3,3-triphen- yldisiloxane,
1,3-dimethoxy-1,1,3,3-tetramethyldisiloxane,
1,3-diethoxy-1,1,3,3-tetramethyldisiloxane,
1,3-diphenoxy-1,1,3,3-tetrame- thyldisiloxane,
1,3-dimethoxy-1,1,3,3-tetramethyldisiloxane,
1,3-diethoxy-1,1,3,3-tetraethyldisiloxane,
1,3-diphenoxy-1,1,3,3-tetraeth- yldisiloxane,
1,3-dimethoxy-1,1,3,3-tetraphenyldisiloxane,
1,3-diethoxy-1,1,3,3-tetraphenyldisiloxane, and
1,3-diphenoxy-1,1,3,3-tet- raphenyldisiloxane.
[0033] Preferred of those compounds are hexamethoxydisiloxane,
hexaethoxydisiloxane, 1,1,3,3-tetramethoxy-1,3-dimethyldisiloxane,
1,1,3,3-tetraethoxy-1,3-dimethyldisiloxane,
1,1,3,3-tetramethoxy-1,3-diph- enyldisiloxane,
1,3-dimethoxy-1,1,3,3-tetramethyldisiloxane,
1,3-diethoxy-1,1,3,3-tetramethyldisiloxane,
1,3-dimethoxy-1,1,3,3-tetraph- enyldisiloxane, and
1,3-diethoxy-1,1,3,3-tetraphenyldisiloxane.
[0034] Examples of the compounds represented by formula (3) wherein
d is 0 include hexamethoxydisilane, hexaethoxydisilane,
hexaphenoxydisilane, 1,1,1,2,2-pentamethoxy-2-methyldisilane,
1,1,1,2,2-pentaethoxy-2-methyldi- silane,
1,1,1,2,2-pentaphenoxy-2-methyldisilane, 1,1,1,2,2-pentamethoxy-2--
ethyldisilane, 1,1,1,2,2-pentaethoxy-2-ethyldisilane,
1,1,1,2,2-pentaphenoxy-2-ethyldisilane,
1,1,1,2,2-pentamethoxy-2-phenyldi- silane,
1,1,1,2,2-pentaethoxy-2-phenyldisilane, 1,1,1,2,2-pentaphenoxy-2-p-
henyldisilane, 1,1,2,2-tetramethoxy-1,2-dimethyldisilane,
1,1,2,2-tetraethoxy-1,2-dimethyldisilane,
1,1,2,2-tetraphenoxy-1,2-dimeth- yldisilane,
1,1,2,2-tetramethoxy-1,2-diethyldisilane,
1,1,2,2-tetraethoxy-1,2-diethyldisilane,
1,1,2,2-tetraphenoxy-1,2-diethyl- disilane,
1,1,2,2-tetramethoxy-1,2-diphenyldisilane,
1,1,2,2-tetraethoxy-1,2-diphenyldisilane,
1,1,2,2-tetraphenoxy-1,2-diphen- yldisilane,
1,1,2-trimethoxy-1,2,2-trimethyldisilane,
1,1,2-triethoxy-1,2,2-trimethyldisilane,
1,1,2-triphenoxy-1,2,2-trimethyl- disilane,
1,1,2-trimethoxy-1,2,2-triethyldisilane, 1,1,2-triethoxy-1,2,2-t-
riethyldisilane, 1,1,2-triphenoxy-1,2,2-triethyldisilane,
1,1,2-trimethoxy-1,2,2-triphenyldisilane,
1,1,2-triethoxy-1,2,2-triphenyl- disilane,
1,1,2-triphenoxy-1,2,2-triphenyldisilane,
1,2-dimethoxy-1,1,2,2-tetramethyldisilane,
1,2-diethoxy-1,1,2,2-tetrameth- yldisilane,
1,2-diphenoxy-1,1,2,2-tetramethyldisilane,
1,2-dimethoxy-1,1,2,2-tetraethyldisilane,
1,2-diethoxy-1,1,2,2-tetraethyl- disilane,
1,2-diphenoxy-1,1,2,2-tetraethyldisilane,
1,2-dimethoxy-1,1,2,2-tetraphenyldisilane,
1,2-diethoxy-1,1,2,2-tetraphen- yldisilane, and
1,2-diphenoxy-1,1,2,2-tetraphenyldisilane.
[0035] Preferred of those compounds are hexamethoxydisilane,
hexaethoxydisilane, 1,1,2,2-tetramethoxy-1,2-dimethyldisilane,
1,1,2,2-tetraethoxy-1,2-dimethyldisilane,
1,1,2,2-tetramethoxy-1,2-diphen- yldisilane,
1,2-dimethoxy-1,1,2,2-tetramethyldisilane,
1,2-diethoxy-1,1,2,2-tetramethyldisilane,
1,2-dimethoxy-1,1,2,2-tetraphen- yldisilane, and
1,2-diethoxy-1,1,2,2-tetraphenyldisilane.
[0036] Examples of the compounds represented by formula (3) wherein
R.sup.7 is a group represented by --(CH.sub.2).sub.n-- include
bis(trimethoxysilyl)methane, bis(triethoxysilyl)methane,
bis(tri-n-propoxysilyl)methane, bis(triisopropoxysilyl)methane,
bis(tri-n-butoxysilyl)methane, bis(tri-sec-butoxysilyl)methane,
bis(tri-t-butoxysilyl)methane, 1,2-bis(trimethoxysilyl)ethane,
1,2-bis(triethoxysilyl)ethane, 1,2-bis(tri-n-propoxysilyl)ethane,
1,2-bis(triisopropoxysilyl)ethane,
1,2-bis(tri-n-butoxysilyl)ethane,
1,2-bis(tri-sec-butoxysilyl)ethane,
1,2-bis(tri-t-butoxysilyl)ethane,
1-(dimethoxymethylsilyl)-1-(trimethoxysilyl)methane,
1-(diethoxymethylsilyl)-1-(triethoxysilyl)methane,
1-(di-n-propoxymethylsilyl)-1-(tri-n-propoxysilyl)methane,
1-(diisopropoxymethylsilyl)-1-(triisopropoxysilyl)methane,
1-(di-n-butoxymethylsilyl)-1-(tri-n-butoxysilyl)methane,
1-(di-sec-butoxymethylsilyl)-1-(tri-sec-butoxysilyl)methane,
1-(di-t-butoxymethylsilyl)-1-(tri-t-butoxysilyl)methane,
1-(dimethoxymethylsilyl)-2-(trimethoxysilyl)ethane,
1-(diethoxymethylsilyl)-2-(triethoxysilyl)ethane, 1-
(di-n-propoxymethylsilyl) -2-(tri-2-n-propoxysilyl)ethane,
1-(diisopropoxymethylsilyl)-2-(triisopropoxysilyl)ethane,
1-(di-n-butoxymethylsilyl)-2-(tri-n-butoxysilyl)ethane,
1-(di-sec-butoxymethylsilyl)-2-(tri-sec-butoxysilyl)ethane,
1-(di-t-butoxymethylsilyl)-2-(tri-t-butoxysilyl)ethane,
bis(dimethoxymethylsilyl)methane, bis(diethoxymethylsilyl)methane,
bis(di-n-propoxymethylsilyl)methane,
bis(diisopropoxymethylsilyl)methane,
bis(di-n-butoxymethylsilyl)methane,
bis(di-sec-butoxymethylsilyl)methane,
bis(di-t-butoxymethylsilyl)methane,
1,2-bis(dimethoxymethylsilyl)ethane,
1,2-bis(diethoxymethylsilyl)ethane,
1,2-bis(di-n-propoxymethylsilyl)ethan- e,
1,2-bis(diisopropoxymethylsilyl)ethane,
1,2-bis(di-n-butoxymethylsilyl)- ethane,
1,2-bis(di-sec-butoxymethylsilyl)ethane, 1,2-bis(di-t-butoxymethyl-
silyl)ethane, 1,2-bis(trimethoxysilyl)benzene,
1,2-bis(triethoxysilyl)benz- ene,
1,2-bis(tri-n-propoxysilyl)benzene,
1,2-bis(triisopropoxysilyl)benzen- e,
1,2-bis(tri-n-butoxysilyl)benzene,
1,2-bis(tri-sec-butoxysilyl)benzene,
1,2-bis(tri-t-butoxysilyl)benzene, 1,3-bis(trimethoxysilyl)benzene,
1,3-bis(triethoxysilyl)benzene, 1,3-bis(tri-n-propoxysilyl)benzene,
1,3-bis(triisopropoxysilyl)benzene,
1,3-bis(tri-n-butoxysilyl)benzene,
1,3-bis(tri-sec-butoxysilyl)benzene, 1,3-bis
(tri-t-butoxysilyl)benzene, 1,4-bis(trimethoxysilyl)benzene,
1,4-bis(triethoxysilyl)benzene, 1,4-bis(tri-n-propoxysilyl)benzene,
1,4-bis(triisopropoxysilyl)benzene,
1,4-bis(tri-n-butoxysilyl)benzene,
1,4-bis(tri-sec-butoxysilyl)benzene, and
1,4-bis(tri-t-butoxysilyl)benzene.
[0037] Preferred of those compounds are
bis(trimethoxysilyl)methane, bis(triethoxysilyl)methane,
1,2-bis(trimethoxysilyl)ethane, 1,2-bis(triethoxysilyl)ethane,
1-(dimethoxymethylsilyl)-1-(trimethoxysily- l)methane,
1-(diethoxymethylsilyl)-1-(triethoxysilyl)methane,
1-(dimethoxymethylsilyl)-2-(trimethoxysilyl)ethane,
1-(diethoxymethylsilyl)-2-(triethoxysilyl)ethane,
bis(dimethoxymethylsily- l)methane,
bis(diethoxymethylsilyl)methane, 1,2-bis(dimethoxymethylsilyl)e-
thane, 1,2-bis(diethoxymethylsilyl)ethane,
1,2-bis(trimethoxysilyl)benzene- , 1,2-bis(triethoxysilyl)benzene,
1,3-bis(trimethoxysilyl)benzene, 1,3-bis(triethoxysilyl)benzene,
1,4-bis(trimethoxysilyl)benzene, and
1,4-bis(triethoxysilyl)benzene.
[0038] In the invention, the compounds (1), (2), and (3) described
above may be used alone or in combination of two or more thereof to
constitute ingredient (A).
[0039] When at least one silane compound selected from the group
consisting of the compounds (1) to (3) as materials for ingredient
(A) is hydrolyzed and condensed, water is preferably used in an
amount of from more than 20 mol to 150 mol per mol of the at least
one compound selected from the compounds (1) to (3). If water is
added in an amount of 20 mol or smaller, there are cases where a
sufficient dielectric constant and a sufficient modulus of
elasticity are not obtained. On the other hand, if the amount of
water added is larger than 150 mol, there are cases where polymer
precipitation or gelation occurs during the hydrolysis and
condensation reactions.
[0040] The production of the product of hydrolysis and condensation
(A) for use in the invention is characterized in that a specific
amount of an alkaline compound is used in hydrolyzing and
condensing at least one silane compound selected from the group
consisting of the compounds (1) to (3).
[0041] In the invention, a silica-based film having a low
dielectric constant and a high modulus of elasticity can be
obtained by using an alkaline compound in an amount not smaller
than a specific value.
[0042] Examples of alkaline compounds which can be used in the
invention include ammonia (including aqueous ammonia solutions),
organic amines, and alkaline inorganic compounds. However, ammonia
and organic amines are preferred in the invention.
[0043] Examples of the organic amines for use in the invention
include alkylamines, alkanolamines, and arylamines.
[0044] Examples of the alkylamines usable in the invention include:
compounds having one or more alkyl groups having 1 to 4 carbon
atoms, such as methylamine, ethylamine, propylamine, butylamine,
hexylamine, octylamine, N,N-dimethylamine, N,N-diethylamine,
N,N-dipropylamine, N,N-dibutylamine, trimethylamine, triethylamine,
tripropylamine, and tributylamine; and
[0045] compounds having an alkoxy group, such as
methoxymethylamine, methoxyethylamine, methoxypropylamine,
methoxybutylamine, ethoxymethylamine, ethoxyethylamine,
ethoxypropylamine, ethoxybutylamine, propoxymethylamine,
propoxyethylamine, propoxypropylamine, propoxybutylamine,
butoxymethylamine, butoxyethylamine, butoxypropylamine, and
butoxybutylamine.
[0046] Examples of the alkanolamines include methanolamine,
ethanolamine, propanolamine, butanolamine, N-methylmethanolamine,
N-ethylmethanolamine, N-propylmethanolamine, N-butylmethanolamine,
N-methylethanolamine, N-ethylethanolamine, N-propylethanolamine,
N-butylethanolamine, N-methylpropanolamine, N-ethylpropanolamine,
N-propylpropanolamine, N-butylpropanolamine, N-methylbutanolamine,
N-ethylbutanolamine, N-propylbutanolamine, N-butylbutanolamine,
N,N-dimethylmethanolamine, N,N-dimethylmethanolamine,
N,N-dipropylmethanolamine, N,N-dibutylmethanolamine,
N,N-dimethylethanolamine, N,N-diethylethanolamine,
N,N-dipropylethanolamine, N,N-dibutylethanolamine,
N,N-dimethylpropanolamine, N,N-diethylpropanolamine,
N,N-dipropylpropanolamine, N,N-dibutylpropanolamine,
N,N-dimethylbutanolamine, N,N-diethylbutanolamine,
N,N-dipropylbutanolamine, N,N-dibutylbutanolamine,
N-methyldimethanolamine, N-ethyldimethanolamine,
N-propyldimethanolamine, N-butyldimethanolamine,
N-methyldiethanolamine, N-ethyldiethanolamine,
N-propyldiethanolamine, N-butyldiethanolamine,
N-methyldipropanolamine, N-ethyldipropanolamine,
N-propyldipropanolamine, N-butyldipropanolamine,
N-methyldibutanolamine, N-ethyldibutanolamine,
N-propyldibutanolamine, N-butyldibutanolamine,
N-(aminomethyl)methanolami- ne, N-(aminomethyl)ethanolamine,
N-(aminomethyl)propanolamine, N-(aminomethyl)butanolamine,
N-(aminoethyl)methanolamine, N-(aminoethyl)ethanolamine,
N-(aminoethyl)propanolamine, N-(aminoethyl)butanolamine,
N-(aminopropyl)methanolamine, N-(aminopropyl)ethanolamine,
N-(aminopropyl)propanolamine, N-(aminopropyl)butanolamine,
N-(aminobutyl)methanolamine, N-(aminobutyl)ethanolamine,
N-(aminobutyl)propanolamine, and N-(aminobutyl)butanolamine.
[0047] Examples of the arylamines include aniline.
[0048] Other examples of the organic amines include
tetramethylethylenediamine, tetraethylethylenediamine,
tetrapropylethylenediamine, tetrabutylethylenediamine,
methylaminomethylamiane, methylaminoethylamine,
methylaminopropylamine, methylaminobutylamine,
ethylaminomethylamine, ethylaminoethylamine, ethylaminopropylamine,
ethylaminobutylamine, propylaminomethylamine,
propylaminoethylamine, propylaminopropylamine,
propylaminobutylamine, butylaminomethylamine, butylaminoethylamine,
butylaminopropylamine, butylaminobutylamine, pyridine, pyrrole,
piperazine, pyrrolidine, piperidine, picoline, morpholine,
methylmorpholine, diazabicyclooctane, diazabicyclononane, and
diazabicycloundecene.
[0049] Those alkaline compounds may be used alone or as a mixture
of two or more thereof.
[0050] From the standpoint of adhesion of the silica-based film to
substrates, it is preferred to use an alkylamine as the alkaline
compound in the invention.
[0051] In the invention, the alkaline compound is used in an amount
of 0.2 mol or larger, preferably 0.9 mol or larger, per mol of the
total amount of the compounds (1) to (3).
[0052] Although there is no particular upper limit on the amount of
the alkaline compound to be used in the invention, the upper limit
thereof is usually less than 10 mol per mol of the silane
compounds.
[0053] The radius of gyration of the product of hydrolysis and
condensation (A) thus obtained is preferably from 5 to 50 nm, more
preferably from 8 to 40 nm, most preferably from 9 to 30 nm, in
terms of radius of gyration determined by the GPC (refractive
index, viscosity, or light scattering) method. When the product of
hydrolysis and condensation has a radius of gyration of from 5 to
50 nm, the composition can give a silica-based film excellent
especially in dielectric constant, modulus of elasticity, and
evenness of the film.
[0054] The product of hydrolysis and condensation (A) thus obtained
is characterized by being not particulate and hence having
excellent applicability to substrates. That the product of
hydrolysis and condensation (A) is not particulate can be
ascertained through examination with, e.g., a transmission electron
microscope (TEM).
[0055] In ingredient (A), the proportion of the product of
hydrolysis and condensation derived from each compound is as
follows, in terms of the product of complete hydrolysis and
condensation. The content of the product of hydrolysis and
condensation derived from the compound (2) is generally from 5 to
75% by weight, preferably from 10 to 70% by weight, more preferably
from 15 to 70% by weight, based on the sum of all the products of
hydrolysis and condensation derived from the compounds (1) to (3).
The content of the product of hydrolysis and condensation derived
from the compound (1) and/or compound (3) is generally from 95 to
25% by weight, preferably from 90 to 30% by weight, more preferably
from 85 to 30% by weight, based on the sum of all the products of
hydrolysis and condensation derived from the compounds (1) to (3).
When the content of the product of hydrolysis and condensation
derived from the compound (2) is from 5 to 75% by weight based on
the sum of all the products of hydrolysis and condensation derived
from the compounds (1) to (3), then the coating film obtained has a
high modulus of elasticity and an exceedingly low dielectric
constant.
[0056] The term "product of complete hydrolysis and condensation"
as used herein means a product in which all the R.sup.1O--,
R.sup.2O--, R.sup.4O--, and R.sup.5O-- groups contained in the
compound (1), (2), or (3) have been hydrolyzed into SiOH groups and
then completely condensed to form siloxane structures.
[0057] Ingredient (A) is preferably a product of the hydrolysis and
condensation of a mixture of at least one of the compounds (1) and
at least one of the compounds (2), because this ingredient (A)
imparts better storage stability to the composition to be
obtained.
[0058] In producing a product of hydrolysis and condensation (A),
at least one silane compound selected from the group consisting of
compounds (1) to (3) is hydrolyzed and condensed in the presence of
an alkylamine so that the resultant product of hydrolysis and
condensation preferably has a radius of gyration of from 5 to 50
nm. It is preferred to adjust the pH of the resultant composition
to 7 or lower.
[0059] Examples of techniques for pH adjustment include:
[0060] (1) to add a pH regulator;
[0061] (2) to distill off the alkali catalyst from the composition
at ordinary or reduced pressure;
[0062] (3) to bubble a gas such as nitrogen or argon into the
composition to thereby remove the alkali catalyst from the
composition; and
[0063] (4) to remove the alkali catalyst from the composition with
an ion-exchange resin.
[0064] Those techniques may be used alone or in combination of two
or more thereof.
[0065] Examples of the pH regulator include inorganic acids and
organic acids.
[0066] Examples of the inorganic acids include hydrochloric acid,
nitric acid, sulfuric acid, hydrofluoric acid, phosphoric acid,
boric acid, and oxalic acid.
[0067] Examples of the organic acids include acetic acid, propionic
acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid,
octanoic acid, nonanoic acid, decanoic acid, oxalic acid, maleic
acid, methylmalonic acid, adipic acid, sebacic acid, gallic acid,
butyric acid, mellitic acid, arachidonic acid, shikimic acid,
2-ethylhexanoic acid, oleic acid, stearic acid, linoleic acid,
linolenic acid, salicylic acid, benzoic acid, p-aminobenzoic acid,
p-toluenesulfonic acid, benzenesulfonic acid, monochloroacetic
acid, dichloroacetic acid, trichloroacetic acid, trifluoroacetic
acid, formic acid, malonic acid, sulfonic acids, phthalic acid,
fumaric acid, citric acid, tartaric acid, succinic acid, malic
acid, itaconic acid, citraconic acid, mesaconic acid, crotonic
acid, and glutaric acid.
[0068] Such a pH regulator is used to adjust the pH of the
composition to 7 or lower, preferably 1 to 6. The method described
above which comprises regulating the radius of gyration of the
product of hydrolysis and condensation to from 5 to 50nm and then
adjusting the pH thereof with the pH regulator to a value within
that range produces the effect that the composition obtained has
improved storage stability.
[0069] The pH regulator is used in an amount suitably selected so
that the pH of the composition becomes a value within that
range.
Organic Solvent (B)
[0070] The composition for film formation of the invention
comprises ingredient (A) usually dissolved or dispersed in an
organic solvent (B).
[0071] This organic solvent (B) may comprise at least one member
selected from the group consisting of alcohol solvents, ketone
solvents, amide solvents, ester solvents, and aprotic solvents.
[0072] Examples of the alcohol solvents include monohydric alcohols
such as methanol, ethanol, n-propanol, isopropanol, n-butanol,
isobutanol, sec-butanol, t-butanol, n-pentanol, isopentanol,
2-methylbutanol, sec-pentanol, t-pentanol, 3-methoxybutanol,
n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol,
sec-heptanol, heptanol-3, n-octanol, 2-ethylhexanol, sec-octanol,
n-nonyl alcohol, 2,6-dimethylheptanol-4, n-decanol,
sec-undecylalcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol,
sec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol,
3,3,5-trimethylcyclohexanol, benzyl alcohol, and diacetone alcohol;
polyhydric alcohols such as ethylene glycol, 1,2-propylene glycol,
1,3-butylene glycol, pentanediol-2,4, 2-methylpentanediol-2,4,
hexanediol-2,5, heptanediol-2,4, 2-ethylhexanediol-1,3, diethylene
glycol, dipropylene glycol, triethylene glycol, and tripropylene
glycol; and partial ethers of polyhydric alcohols, such as ethylene
glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene
glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene
glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene
glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether,
diethylene glycol monoethyl ether, diethylene glycol monopropyl
ether, diethylene glycol monobutyl ether, diethylene glycol
monohexyl ether, propylene glycol monomethyl ether, propylene
glycol monoethyl ether, propylene glycol monopropyl ether,
propylene glycol monobutyl ether, dipropylene glycol monomethyl
ether, dipropylene glycol monoethyl ether, and dipropylene glycol
monopropyl ether.
[0073] Those alcohol solvents may be used alone or in combination
of two or more thereof.
[0074] Preferred of those alcohols are n-propanol, isopropanol,
n-butanol, isobutanol, sec-butanol, t-butanol, n-pentanol,
isopentanol, 2-methylbutanol, sec-pentanol, t-pentanol,
3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol,
2-ethylbutanol, propylene glycol monomethyl ether, propylene glycol
monoethyl ether, propylene glycol monopropyl ether, and propylene
glycol monobutyl ether.
[0075] Examples of the ketone solvents include acetone, methyl
ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone,
diethyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone,
ethyl n-butyl ketone, methyl n-hexyl ketone, dmsobutyl ketone,
trimethylnonanone, cyclohexanone, 2-hexanone, methylcyclohexanone,
2,4-pentanedione, acetonylacetone, acetophenone, and fenchone.
Examples thereof further include .beta.-diketones such as
acetylacetone, 2,4-hexanedione, 2,4-heptanedione, 3,5-heptanedione,
2,4-octanedione, 3,5-octanedione, 2,4-nonanedione, 3,5-nonanedione,
5-methyl-2,4-hexanedione, 2,2,6,6-tetramethyl-3,5-heptanedione, and
1,1,1,5,5,5-hexafluoro-2,4-hept- anedione.
[0076] Those ketone solvents may be used alone or in combination of
two or more thereof.
[0077] Examples of the amide solvents include formamide,
N-methylformamide, N,N-dimethylformamide, N-ethylformamide,
N,N-diethylformamide, acetamide, N-methylacetamide,
N,N-dimethylacetamide, N-ethylacetamide, N,N-diethylacetamide,
N-methylpropionamide, N-methylpyrrolidone, N-formylmorpholine,
N-formylpiperidine, N-formylpyrrolidine, N-acetylmorpholine,
N-acetylpiperidine, and N-acetylpyrrolidine.
[0078] Those amide solvents may be used alone or in combination of
two or more thereof.
[0079] Examples of the ester solvents include diethyl carbonate,
ethylene carbonate, propylene carbonate, methyl acetate, ethyl
acetate, .gamma.-butyrolactone, .gamma.-valerolactone, n-propyl
acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate,
sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate,
3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate,
2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate,
methylcyclohexyl acetate, n-nonyl acetate, methyl acetoacetate,
ethyl acetoacetate, ethylene glycol monomethyl ether acetate,
ethylene glycol monoethyl ether acetate, diethylene glycol
monomethyl ether acetate, diethylene glycol monoethyl ether
acetate, diethylene glycol mono-n-butyl ether acetate, propylene
glycol monomethyl ether acetate, propylene glycol monoethyl ether
acetate, propylene glycol monopropyl ether acetate, propylene
glycol monobutyl ether acetate, dipropylene glycol monomethyl ether
acetate, dipropylene glycol monoethyl ether acetate, glycol
diacetate, methoxytriglycol acetate, ethyl propionate, n-butyl
propionate, isoamyl propionate, diethyl oxalate, di-n-butyl
oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl
lactate, diethyl malonate, dimethylphthalate, and diethyl
phthalate.
[0080] Those ester solvents may be used alone or in combination of
two or more thereof.
[0081] Examples of the aprotic solvents include acetonitrile,
dimethyl sulfoxide, N,N,N',N'-tetraethylsulfamide,
hexamethylphosphoric triamide, N-methylmorpholine, N-methylpyrrole,
N-ethylpyrrole, N-methyl-.DELTA..sup.3-pyrroline,
N-methylpiperidine, N-ethylpiperidine, N,N-dimethylpiperazine,
N-methylimidazole, N-methyl-4-piperidone, N-methyl-2-piperidone,
N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidi- none, and
1,3-dimethyltetrahydro-2(1H)-pyrimidinone.
[0082] The organic solvents (B) enumerated above can be used alone
or as a mixture of two or more thereof.
[0083] Preferred of those organic solvents are alcohol
solvents.
[0084] In producing the composition for film formation of the
invention, the same organic solvents can be used for the
hydrolyzing and condensing the compounds (1) to (3) as materials
for ingredient (A).
[0085] Specifically, water or solvent-diluted water is added
intermittently or continuously to a solvent containing the
compounds (1) to (3) dissolved therein. In this operation, an
alkaline compound may be added beforehand to the solvent or may be
dissolved or dispersed in the water prior to the addition of the
water. The reaction temperature in this case is generally from 0 to
100.degree. C., preferably from 15 to 90.degree. C.
Other Additives
[0086] Ingredients such as surfactants, colloidal silica, and
colloidal alumina may be added to the composition for film
formation of the invention.
[0087] The surfactants for use in the invention are not
particularly limited. Examples thereof include silicone
surfactants, cationic surfactants, anionic surfactants, nonionic
surfactants, amphoteric surfactants, fluorochemical surfactants,
and acrylic surfactants. Such surfactants can be used alone or in
combination of two or more thereof.
[0088] Preferred surfactants are silicone, nonionic,
fluorochemical, and acrylic surfactants. Especially preferred of
these are silicone surfactants because they are effective in
imparting excellent film-forming properties and do not generate a
gas which corrodes metals.
[0089] The silicone surfactants are not particularly limited.
[0090] Examples thereof include
dimethylpolysiloxane-polyoxyalkylene copolymers.
[0091] Commercially available products of silicone surfactants
include organosiloxane polymer KP341 (manufactured by Shin-Etsu
Chemical Co., Ltd.) and SH7PA, SH21PA, SH28PA, SH30PA, and ST94PA
(all manufactured by Dow Corning Toray Silicone Co., Ltd.).
[0092] Examples of the cationic surfactants include alkylamine
salts, quaternary ammonium salts, and polyoxyalkylamines.
[0093] Examples of the anionic surfactants include fatty acid
salts, higher alcohol sulfates, alkylbenzenesulfonates, (diphenyl
ether)disulfonates, dialkyl disulfosuccinates, alkyl phosphate
salts, and polyoxyethylene sulfate salts.
[0094] The nonionic surfactants are not particularly limited.
Examples thereof include polyoxyethylene alkyl ethers such as
polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and
polyoxyethylene oleyl ether; polyoxyethylene aryl ethers such as
polyoxyethylene octylphenyl ether and polyoxyethylene nonylphenyl
ether; polyoxyethylene dialkyl esters such as polyoxyethylene
dilaurate and polyoxyethylene distearate; sorbitan fatty acid
esters; fatty-acid-modified polyoxyethylenes; and
polyoxyethylene-polyoxypropylene block copolymers.
[0095] The amphoteric surfactants are not particularly limited.
Examples thereof include surfactants having a structure comprising
a combination of two or more different kinds of surfactants
selected from the anionic surfactants, cationic surfactants, and
nonionic surfactants enumerated above.
[0096] The fluorochemical surfactants are ones comprising a
compound having a fluoroalkyl or fluoroalkylene group in at least
one position selected from the ends, main chain, and side chains.
Examples thereof include 1,1,2,2-tetrafluorooctyl
1,1,2,2-tetrafluoropropyl ether, 1,1,2,2-tetrafluorooctyl hexyl
ether, octaethylene glycol di(1,1,2,2-tetrafluorobutyl) ether,
hexaethylene glycol (1,1,2,2,3,3-hexafluoropentyl) ether,
octapropylene glycol di(1,1,2,2-tetrafluorobutyl) ether,
hexapropylene glycol di(1,1,2,2,3,3-hexafluoropentyl) ether, sodium
perfluorododecanesulfonate- ,
1,1,2,2,8,8,9,9,10,10-decafluorododecane,
1,1,2,2,3,3-hexafluorodecane,
N-[3-perfluorooctanesulfonamido)propyl]-N,N'-dimethyl-N-carboxymethylene
ammonium betaine, perfluoroalkylsulfonamidopropyltrimethyl ammonium
salts, perfluoroalkyl-N-ethylsulfonyl glycine salts,
bis(N-perfluorooctylsulfonyl-N-ethylaminoethyl) phosphate, and
monoperfluoroalkylethyl phosphates.
[0097] Commercially available products of such fluorochemical
surfactants include products available under the trade names of
Megafac F142D, F172, F173, and F183 (manufactured by Dainippon Ink
& Chemicals, Inc.); F-Top EF301, EF303, and EF352 (manufactured
by New Akita Chemical Company) Fluorad FC-430 and FC-431
(manufactured by Sumitomo 3M Ltd.); Asahi Guard AG710 and Surflon
S-382, SC-101, SC-102, SC-103, SC-104, SC-105, and SC-106
(manufactured by Asahi Glass Co., Ltd.); BM-1000 and BM-1100
(manufactured by Yusho K.K.); and NBX-15 (manufactured by NEOS Co.,
Ltd.). Especially preferred of these are Megafac F172, BM-1000,
BM-1100, and NBX-15.
[0098] Examples of the acrylic surfactants which can be used in the
invention include (meth)acrylic acid copolymers. Such acrylic
surfactants are commercially available under the trade names of
Polyflow No.57 and No.95, manufactured by Kyoeisha Chemical Co.,
Ltd.
[0099] The colloidal silica is a dispersion comprising, for
example, any of the aforementioned hydrophilic organic solvents and
high-purity silicic acid anhydride dispersed therein. It has an
average particle diameter of generally from 5 to 30 nm, preferably
from 10 to 20 nm, and a solid concentration of generally about from
10 to 40% by weight. Examples of the colloidal silica include the
methanol silica sol and isopropanol silica sol manufactured by
Nissan Chemical Industries, Ltd., and Oscal, manufactured by
Catalysts & Chemicals Industries Co., Ltd.
[0100] Examples of the colloidal alumina include Alumina Sol 520,
100, and 200, manufactured by Nissan Chemical Industries, Ltd., and
Alumina Clear Sol and Alumina Sol 10 and 132, manufactured by
Kawaken Fine Chemicals Co., Ltd.
Methods for Preparing the Composition for Film Formation
[0101] The composition for film formation of the invention may be
prepared, for example, by mixing compounds (1) to (3) in a solvent,
adding water thereto continuously or intermittently, and conducting
hydrolysis and condensation to prepare ingredient (A).
[0102] Specific examples of methods for preparing the composition
of the invention include the following methods (1) to (4).
[0103] (1) A method in which a given amount of water is added to a
mixture comprising compounds (1) to (3) for constituting ingredient
(A) , an alkaline compound, and an organic solvent (B) to conduct
hydrolysis and condensation reactions.
[0104] (2) A method in which a given amount of water is added
continuously or intermittently to a mixture comprising compounds
(1) to (3) for constituting ingredient (A), an alkaline compound,
and an organic solvent (B) to conduct hydrolysis and condensation
reactions.
[0105] (3) A method in which given amounts of water and an alkaline
compound are added to a mixture comprising compounds (1) to (3) for
constituting ingredient (A) and an organic solvent (B) to conduct
hydrolysis and condensation reactions.
[0106] (4) A method in which given amounts of water and an alkaline
compound are added continuously or intermittently to a mixture
comprising compounds (1) to (3) for constituting ingredient (A) and
an organic solvent (B) to conduct hydrolysis and condensation
reactions.
[0107] The organic solvent to be used in hydrolyzing and condensing
compounds (1) to (3) in the invention are preferably alcohols
having up to 4 carbon atoms, such as methanol, ethanol, and
isopropanol.
[0108] After completion of the hydrolysis and condensation,
concentration adjustment and solvent replacement are conducted
according to need. Thus, the composition of the invention is
prepared.
[0109] The composition of the invention thus obtained has a total
solid concentration of preferably from 2 to 30% by weight. The
solid concentration thereof is suitably regulated according to the
intended use thereof. When the composition has a total solid
concentration of from 2 to 30% by weight, the composition not only
gives a coating film having an appropriate thickness but has better
storage stability.
[0110] The total solid concentration of the composition is
regulated, according to need, by means of concentration or dilution
with the organic solvent (B).
[0111] In forming a film from the composition of the invention, the
composition of the invention is first applied to a substrate to
form a coating film.
[0112] Examples of the substrate to which the composition of the
invention is applicable include semiconductors, glasses, ceramics,
and metals.
[0113] Examples of coating techniques that can be used include spin
coating, dipping, and roller blade coating.
[0114] The composition of the invention is especially suitable for
use in an application in which the composition is applied to a
silicon wafer, SiO.sub.2 wafer, SiN wafer, or the like to form an
insulating film.
[0115] This coating operation can be conducted so as to form a
coating film having a thickness on a dry basis of about from 0.05
to 1.5 .mu.m in the case of single coating or about from 0.1 to 3
.mu.m in the case of double coating.
[0116] In general, the thickness of the coating film to be formed
is from 0.2 to 20 .mu.m.
[0117] In this operation, heating can be conducted with a hot
plate, oven, furnace, or the like, for example, in the air, in a
nitrogen or argon atmosphere, under vacuum, or under reduced
pressure having a controlled oxygen concentration.
[0118] In order to control the curing rate of the ingredient (A),
stepwise heating or a suitably selected atmosphere, such as a
nitrogen, air, oxygen, or reduced-pressure atmosphere, can be used
according to need.
[0119] The silica-based film of the invention thus obtained has a
density of generally from 0.35 to 1.2 g/cm.sup.3, preferably from
0.4 to 1.1 g/cm.sup.3, more preferably from 0.5 to 1.0 g/cm.sup.3.
If the density of the film is lower than 0.35 g/cm.sup.3, the
coating film has impaired mechanical strength. On the other hand,
if the density thereof exceeds 1.2 g/cm.sup.3, a low dielectric
constant cannot be obtained.
[0120] When the silica-based film of the invention is examined for
pore size distribution by the BJH method, no pores of 10 nm or
larger are observed therein. The film is hence suitable for use as
an interlayer insulating film material for insulation between fine
wirings.
[0121] Furthermore, the silica-based film of the invention is
characterized by having low water absorption. For example, when the
coating film is allowed to stand in an atmosphere of 127.degree.
C., 2.5 atm, and 100% RH for 1 hour, then no water adsorption on
the coating film is observed by IR spectroscopy.
[0122] This water absorption can be regulated by controlling the
amount of a tetraalkoxysilane used in the invention as a compound
(1) in preparing the composition for film formation.
[0123] The silica-based film of the invention has a dielectric
constant as low as generally from 2.5 to 1.2, preferably from 2.4
to 1.2.
[0124] The low-density coating film of the invention has excellent
insulating properties and is excellent also in evenness, dielectric
characteristics, cracking resistance, and surface hardness.
Consequently, this coating film is useful in applications such as
interlayer insulating films for semiconductor devices such as LSIs,
system LSIs, DRAMs, SDRAMs, RDRAMs, and D-RDRAMs, protective films
such as surface coat films for semiconductor devices, interlayer
insulating films for multilayered printed circuit boards, and
protective or insulating films for liquid-crystal display
devices.
[0125] The invention will be explained below in more detail by
reference to the following Examples. However, the following
description merely shows general embodiment examples of the
invention, and it should be understood that the invention is not
construed as being limited by the description without particular
reasons.
[0126] In the following Examples and Reference Examples, all
"parts" and "percents" are by weight unless otherwise
indicated.
[0127] Various properties were evaluated by the following
methods.
Radius of Gyration
[0128] Measured by gel permeation chromatography (GPC) (refractive
index, viscosity, or light scattering measurement) under the
following conditions.
[0129] Sample solution: A product of the hydrolysis and
condensation of silane compounds was diluted with methanol
containing 10 mM LiBr to a solid concentration of 0.25% to prepare
a sample solution for GPC (refractive index, viscosity, or light
scattering measurement).
[0130] Apparatus:
[0131] GPC system: Model GPC-8020, manufactured by Tosoh Corp.
[0132] Column: Alpha 5000/3000, manufactured by Tosoh Corp.
[0133] Viscosity detector and light scattering detector:
[0134] Model T-60 Dual Meter, manufactured by Visco Tech Co.
[0135] Carrier solution: methanol containing 10 mM LiBr
[0136] Carrier feed rate: 1 ml/min
[0137] Column temperature: 40.degree. C.
Dielectric Constant
[0138] A sample for dielectric constant measurement was produced by
forming an aluminum electrode pattern by vapor deposition on a film
obtained.
[0139] This sample was examined at a frequency of 100 kHz with
electrodes HP16451B and precision LCR meter HP4284A, both
manufactured by Yokogawa-Hewlett-Packard, Ltd., by the CV method to
determine the dielectric constant of the coating film.
Modulus of Elasticity (Young's Modulus)
[0140] A film obtained was examined with Nanoindenter XP
(manufactured by Nano Instrument Inc.) by a continuous method for
rigidity measurement.
EXAMPLE 1
[0141] To a solution prepared by mixing 6 g of 40% aqueous
methylamine solution, 228 g of ultrapure water, and 570 g of
ethanol were added 13.6 g of methyltrimethoxysilane and 20.9 g of
tetraethoxysilane. This mixture was reacted at 60.degree. C. for 2
hours, and 200 g of propylene glycol monopropyl ether was then
added thereto. The resultant mixture was concentrated under reduced
pressure until the total amount thereof decreased to 116 g.
Subsequently, 10 g of a 10% acetic acid solution in propylene
glycol monopropyl ether was added to the concentrate to obtain a
composition solution having a solid content of 10%.
[0142] The product of hydrolysis and condensation contained in the
composition solution obtained had a radius of gyration of 12
nm.
EXAMPLE 2
[0143] The same procedure as in Example 1 was conducted, except
that 98 g of 25% aqueous ammonia solution was used in place of the
6 g of 40% aqueous methylamine solution. Thus, a composition
solution having a solid content of 10% was obtained.
[0144] The product of hydrolysis and condensation contained in the
composition solution obtained had a radius of gyration of 14
nm.
EXAMPLE 3
[0145] To a solution prepared by mixing 27 g of 40% aqueous
methylamine solution, 137 g of ultrapure water, and 342 g of
ethanol were added 13.6 g of methyltrimethoxysilane and 28.7 g of
tetraethoxysilane. This mixture was reacted at 60.degree. C. for 2
hours, and 200 g of propylene glycol monopropyl ether was then
added thereto. The resultant mixture was concentrated under reduced
pressure until the total amount thereof decreased to 116 g.
Subsequently, 10 g of a 10% acetic acid solution in propylene
glycol monopropyl ether was added to the concentrate to obtain a
composition solution having a solid content of 10%.
[0146] The product of hydrolysis and condensation contained in the
composition solution obtained had a radius of gyration of 26
nm.
REFERENCE EXAMPLE 1
[0147] The same procedure as in Example 1 was conducted, except
that 1 g of 25% aqueous ammonia solution was used in place of the 6
g of 40% aqueous methylamine solution. Thus, a composition solution
having a solid content of 10% was obtained.
[0148] The product of hydrolysis and condensation contained in the
composition solution obtained had a radius of gyration of 8 nm.
REFERENCE EXAMPLE 2
[0149] The same procedure as in Example 1 was conducted, except
that the amount of the ultrapure water to be used was changed to 14
g. Thus, a composition solution having a solid content of 10% was
obtained.
[0150] The product of hydrolysis and condensation contained in the
composition solution obtained had a radius of gyration of 4 nm.
REFERENCE EXAMPLE 3
[0151] The same procedure as in Example 1 was conducted, except
that the amount of the ultrapure water to be used was changed to
690 g. However, polymer precipitation occurred during the
reaction.
Film Formation
[0152] The compositions obtained in Examples 1 to 3 and Reference
Examples 1 and 2 each was applied to an 8-inch silicon wafer by
spin coating. The coated wafer was heated first at 80.degree. C. in
the air for 5 minutes and then at 200.degree. C. in nitrogen for 5
minutes, subsequently heated under vacuum at 340.degree. C.,
360.degree. C., and 380.degree. C. in this order for 30 minutes
each, and then heated under vacuum at 425.degree. C. for 1 hour to
form a colorless transparent silica-based film. The silica-based
films thus obtained were subjected to the evaluations described
above. The results obtained are shown in Table 1.
1 TABLE 1 Example Example Example Reference Reference 1 2 3 Example
1 Example 2 Dielectric 2.3 2.2 2.0 2.6 2.9 constant Modulus of 5.5
5.0 4.0 2.8 2.0 elasticity (GPa)
SYNTHESIS EXAMPLE 1
[0153] Into a separable flask made of quartz were introduced 5,700
g of distilled ethanol, 1,600 g of ion-exchanged water, and 1,300 g
of 10% aqueous ammonia solution. The contents were stirred and
homogenized. To this solution was added over 30 minutes a mixture
of 136 g of methyltrimethoxysilane and 209 g of tetraethoxysilane.
The resultant solution was reacted for 2 hours while being kept at
55.degree. C. To this solution was added 3,000 g of propylene
glycol monopropyl ether. Subsequently, the resultant solution was
concentrated with a 50.degree. C. evaporator until the
concentration thereof reached 10% (in terms of the content of the
product of complete hydrolysis and condensation). Thereafter, 10 g
of a 10% acetic acid solution in propylene glycol monopropyl ether
was added to the concentrate to obtain a reaction mixture (1).
[0154] The product of condensation and other reactions thus
obtained had a radius of gyration of 14.4 nm.
SYNTHESIS EXAMPLE 2
[0155] The same procedure as in synthesis example 1 was conducted,
except that the amount of the ion-exchanged water was changed from
1,600 g to 260 g. Thus, a reaction mixture (2) was obtained.
[0156] The product of condensation and other reactions thus
obtained had a radius of gyration of 13.4 nm.
SYNTHESIS EXAMPLE 3
[0157] The same procedure as in synthesis example 1 was conducted,
except that the amount of the ion-exchanged water was changed from
1,600 g to 3,150 g. Thus, a reaction mixture (3) was obtained.
[0158] The product of condensation and other reactions thus
obtained had a radius of gyration of 15.2 nm.
SYNTHESIS EXAMPLE 4
[0159] The same procedure as in synthesis example 1 was conducted,
except that 1,300 g of 10% aqueous methylamine solution was used in
place of the 1,300 g of 10% aqueous ammonia solution. Thus, a
reaction mixture (4) was obtained.
[0160] The product of condensation and other reactions thus
obtained had a radius of gyration of 15.4 nm.
EXAMPLE 4
[0161] The reaction mixture (1) obtained in Synthesis Example 1 was
filtered through a Teflon filter having an opening diameter of 0.2
.mu.m to obtain a composition for film formation of the
invention.
[0162] The composition obtained was applied to a silicon wafer by
spin coating, and the coating film formed was evaluated for
dielectric constant by the same method as described above and
further evaluated for other properties by the following methods.
The results obtained are shown in Table 2.
Cracking Resistance
[0163] The composition sample was applied to an 8-inch silicon
wafer by spin coating in such an amount as to result in a cured
coating film having a thickness of 1.0 .mu.m. This coating film was
dried first at 90.degree. C. on a hot plate for 3 minutes and then
at200.degree. C. in a nitrogen atmosphere for 3 minutes.
Subsequently, the coated substrate was burned on a 400.degree. C.
hot plate in an argon atmosphere for 30 minutes. The coating film
obtained was partly incised with a knife and then immersed in pure
water for 1 hour. Thereafter, the incision of the coating film was
examined with a microscope to evaluate cracking resistance based on
the following criteria.
[0164] .largecircle.: No crack propagation was observed.
[0165] X: Crack propagation was observed.
Resistance of Coating Film to CMP
[0166] The composition sample was applied to an 8-inch silicon
wafer by spin coating. The coated substrate was dried first at
90.degree. C. on a hot plate for 3 minutes and subsequently at
200.degree. C. in a nitrogen atmosphere for 3 minutes, and was then
burned on a 400.degree. C. hot plate in an argon atmosphere for 30
minutes. The coating film obtained was polished under the following
conditions.
[0167] Slurry: silica-hydrogen peroxide system
[0168] Polishing pressure: 200 g/cm.sup.2
[0169] Polishing time: 40 seconds
[0170] After the CMP, the appearance of the coating film was
examined with a lamp for surface examination at an illuminance of
350,000 1 x to evaluate CMP resistance based on the following
criteria.
[0171] .largecircle.: No change.
[0172] X: Mars or peeling was observed in the coating film.
Adhesion of Coating Film
[0173] The composition sample was applied to an 8-inch silicon
wafer by spin coating. The coated substrate was dried first at
90.degree. C. on a hot plate for 3 minutes and subsequently at
200.degree. C. in a nitrogen atmosphere for 3 minutes, and was then
burned on a 400.degree. C. hot plate in an argon atmosphere for 30
minutes. Ten stud pins were fixed to the resultant coated substrate
with an epoxy resin. After the epoxy resin applied was cured at
150.degree. C. for 1 hour, the stud pins were pulled out by the
Sebastian method to evaluate the adhesion of the coating film based
on the following criteria.
[0174] .largecircle.: No peeling occurred between the silicon wafer
and the coating film with respect to each of the ten stud pins.
[0175] X: Peeling occurred between the silicon wafer and the
coating film.
EXAMPLES 5 TO 7
[0176] Compositions for film formation were prepared in the same
manner as in Example 4, except that each of the reaction mixtures
shown in Table 2 was used in place of reaction mixture (1). The
compositions obtained were evaluated in the same manner as in
Example 4. The results of the evaluations are shown in Table 2.
2TABLE 2 Cracking CMP Dielectric resistance resistance Adhesion
constant of of of of Exam- Reaction coating coating coating coating
ple mixture film film film film 4 Reaction 2.19 .largecircle.
.largecircle. .largecircle. mixture (1) 5 Reaction 2.25
.largecircle. .largecircle. .largecircle. mixture (2) 6 Reaction
2.16 .largecircle. .largecircle. .largecircle. mixture (3) 7
Reaction 2.14 .largecircle. .largecircle. .largecircle. mixture
(4)
[0177] According to the invention, a composition for film formation
can be provided which is capable of forming a silica-based film
having a sufficiently low dielectric constant and improved
mechanical strength.
* * * * *