Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2000-09-27
2002-06-25
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C528S021000, C528S010000, C528S012000, C528S031000, C528S032000, C528S033000, C525S100000, C427S372200, C427S387000
Reexamination Certificate
active
06410150
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a polyorganosiloxane-based composition for film formation. More particularly, the invention relates to a polyorganosiloxane-based 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 film having a low dielectric constant and high modulus of elasticity.
BACKGROUND OF THE INVENTION
Silica (SiO
2
) films formed by vacuum processes such as CVD method have hitherto been used frequently as interlayer insulating films in semiconductor devices and the like. 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 trend toward higher degree of integration in semiconductor devices and the like, an interlayer insulating film has been developed which comprises a polyorganosiloxane as the main component, has a low dielectric constant, and is called an organic SOG film.
However, the dielectric constants of the currently known organic SOG films are about from 3 to 4, and no organic SOG film is known which has a lower dielectric constant than those and has sufficient mechanical strength.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide a composition for film formation that overcomes the problems described above.
Another object of the invention is to provide a polyorganosiloxane-based composition for film formation which is capable of giving a cured film having a low dielectric constant and high modulus of elasticity and useful as an interlayer insulating film in semiconductor devices and the like.
The invention provides a composition for film formation which comprises
(A) a product of hydrolysis and condensation (hereinafter referred to as a “product of hydrolysis and condensation (A)”) obtained by hydrolyzing and condensing, in the presence of an alkali catalyst, at least one silane compound 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 as “compounds (2)”), and compounds represented by the following formula (3) (hereinafter referred to as “compounds (3)”), and
(B) a product of hydrolysis and condensation (hereinafter referred to as a “product of hydrolysis and condensation (B)”) obtained by hydrolyzing and condensing, in the presence of an acid catalyst, at least one silane compound selected from the group consisting of the compounds (1), the compounds (2), and the compounds (3):
R
a
Si(OR
1
)
4−a
(1)
wherein R represents hydrogen atom, fluorine atom or a monovalent organic group; R
1
represents a monovalent organic group; and a is an integer of 1 or 2;
Si(OR
2
)
4
(2)
wherein R
2
represents a monovalent organic group;
R
3
b
(R
4
O)
3−b
Si—(R
7
)
d
—Si(OR
5
)
3−c
R
6
c
(3)
wherein R
3
to R
6
may be the same or different and each represent a monovalent organic group; b and c may be the same or different and each are an integer of 0 to 2; R
7
represents oxygen atom, a phenylene group or a group represented by —(CH
2
)
n
—, wherein n is an integer of 1 to 6; and d is 0 or 1.
In this composition, the product of hydrolysis and condensation (A) preferably has a weight average molecular weight as determined by GPC of from 50,000 to 10,000,000.
The product of hydrolysis and condensation (B) preferably has a weight average molecular weight as determined by GPC of from 500 to 300,000.
The ingredient (A) preferably contains a product of the hydrolysis and condensation of at least one compound represented by the formula (2) in an amount of from 5 to 75% by weight (in terms of the product of complete hydrolysis and condensation).
The ingredient (A) preferably is a product of the hydrolysis and condensation of silane compounds comprising at least one compound represented by the formula (1) and at least one compound represented by the formula (2).
The ingredients (A) and (B) are preferably contained in such a proportion that the amount of the ingredient (B) is from 1 to 900 parts by weight (in terms of the product of complete hydrolysis and condensation) per 100 parts by weight of the ingredient (A) (in terms of the product of complete hydrolysis and condensation).
Furthermore, the composition for film formation of the invention preferably has a pH of 7 or lower.
The invention further provides a method of film formation which comprises applying the composition for film formation described above on a substrate and then heating the composition.
A preferred application of the film obtained by the method of film formation described above is an insulating film.
The invention furthermore provides a semiconductor device having the insulating film.
DETAILED DESCRIPTION OF THE INVENTION
The composition for film formation of the invention is a polyorganosiloxane-based composition which contains ingredient (A) [a product of hydrolysis and condensation (a hydrolyzate and/or a condensate thereof) obtained by hydrolyzing and condensing, in the presence of an alkali catalyst, at least one member selected from the group consisting of compounds (1), (2), and (3)] and ingredient (B) [a product of hydrolysis and condensation (a hydrolyzate and/or a condensate thereof) obtained by hydrolyzing and condensing, in the presence of an acid catalyst, at least one member selected from the group consisting of compounds (1), (2), and (3)] as film-forming base polymers. When this composition of the invention is applied to a substrate such as, e.g., a silicon wafer by dipping, spin coating, or another technique and the composition applied is heated to thermally condensation-polymerize the ingredients (A) and (B), then the ingredients (A) and (B) give a vitreous or macromolecular weight film which has a low dielectric constant, high modulus of elasticity, and hence excellent mechanical strength. Thus, an interlayer insulating film material can be formed.
The term “hydrolysis” as used herein means that the R
1
O—, R
2
O—, R
4
O—, and R
5
O— groups in compounds (1) to (3) to constitute ingredients (A) and (B) react with water to produce silanol groups.
The term “condensation” as used herein means that silanol groups of the hydrolyzates of compounds (1) to (3) to constitute ingredients (A) and (B) are condensed to form Si—O—Si bonds. In the invention, however, all the silanol groups need not have undergone condensation. Namely, the condensation include the production of a condensate in which a slight proportion of the silanol groups have been condensed and the production of a mixture of condensates which differ in the degree of condensation.
Product of Hydrolysis and Condensation (A)
The product of hydrolysis and condensation (A) is obtained by hydrolyzing and condensing, in the presence of an alkali catalyst, at least one silane compound selected from the group consisting of compounds (1) to (3). Compounds (1) to (3) and the alkali catalyst are described below.
Compounds (1):
Examples of the monovalent organic groups represented by R and R
1
in the formula (1) include alkyl group, aryl group, allyl group, and glycidyl group. In the formula (1), R is preferably a monovalent organic group, especially alkyl group or phenyl group.
The alkyl group preferably has 1 to 5 carbon atoms, and examples thereof include methyl, ethyl, propyl, and butyl. Those alkyl groups may be linear or branched, and may be ones in which one or more of the hydrogen atoms have been replaced with, for example, fluorine atoms.
In the formula (1), examples of the aryl group include phenyl, naphthyl, methylphenyl, ethylphenyl, chlorophenyl, bromophenyl, and fluorophenyl.
Specific examples of the compounds represented by the formula (1) include: trimethoxysilane, triethoxysilane, tri-n-propoxysilane, triisopropoxysilane, tri-n-bu
Hayashi Eiji
Konno Keiji
Kurosawa Takahiko
Shiota Atsushi
Yamada Kinji
Dawson Robert
JSR Corporation
Keehan Christopher M.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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