Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2002-09-24
2004-06-15
Buttner, David J. (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S212000, C428S448000, C427S407100, C427S387000
Reexamination Certificate
active
06749944
ABSTRACT:
FILED OF THE INVENTION
The present invention relates to a stacked film, a method for the formation of a stacked film, an insulating film and a substrate for semiconductors. More particularly, it relates to a stacked film comprising films each having specific mean radius of gyration, a method for the formation of the stacked film, an insulating film obtained by the film formation method, having superior adhesion to a film formed by a CVD (Chemical Vapor Deposition) process as a dielectric film in, for example, semiconductor devices, and a substrate for semiconductors, comprising the insulating film.
DESCRIPTION OF THE RELATED ART
Hitherto, silica (SiO
2
) films formed by a vacuum process such as a CVD process have been widely used as dielectric films in, for example, semiconductor devices. In recent years, insulating films of a coating type, comprising a hydrolyzate of a tetraalkoxysilane as a major component, which are called as SOG (Spin on Glass) films, have also been used for the purpose of forming more uniform dielectric films. In addition, as the degree of integration of, for example, semiconductor devices becomes large, dielectric films having a low dielectric constant, comprising, as a major component, a polyorganosiloxane called “organic SOG”, have been developed.
Especially, for example, as the semiconductor devices become larger in degree of integration or more multiple in lamination, dielectric film materials having a lower dielectric constant, preferably a dielectric constant of 2.5 or less, and having superior adhesion to a substrate, have been being demanded.
As materials having a low dielectric constant, compositions comprising a mixture of fine particles obtained by condensation of an alkoxysilane in the presence of ammonia and a basic partial hydrolyzate of an alkoxysilane (see JP-A-5-263045 and JP-A-5-315319) and coating solutions obtained by condensation of a basic partial hydrolyzate of a polyalkoxysilane in the presence of ammonia (see JP-A-11-340219 and JP-A-11-340220) have been proposed. However, these materials involved problems such that when used singly, the adhesion to a substrate is inferior and that the dielectric constant exceeds 2.5.
SUMMARY OF THE INVENTION
The present invention has been made to overcome the above-described problems.
Accordingly, one object of the present invention is to provide a stacked film.
Another object of the present invention is to provide a method for the formation of the stacked film.
Still another object of the present invention is to provide an insulating film for semiconductor obtained by the film formation method, having superior adhesion to a film formed by a CVD process as a dielectric film in, for example, semiconductor devices.
Further object of the present invention is to provide a substrate for semiconductors, comprising the insulating film.
The stacked film according to one embodiment of the present invention comprises (A) a film prepared by heat curing (a) an alkoxysilane hydrolysis condensate having a mean radius of gyration of from 10 to 30 nm in the form of a solution, and (B) a film prepared by heat curing (b) an alkoxysilane hydrolysis condensate having a mean radius of gyration of less than 10 nm in the form of solution, with a difference in the mean radius of gyration between the alkoxysilane hydrolysis condensate (a) and the alkoxysilane hydrolysis condensate (b) being 5 nm or more.
The stacked film according to another embodiment of the present invention comprises (A) a film having a dielectric constant of 2.5 or less, which is prepared by heat curing (a) an alkoxysilane hydrolysis condensate in the form of a solution, and (B) a film having a dielectric constant exceeding 2.5, which is prepared by heat curing (b) an alkoxysilane hydrolysis condensate in the form of a solution, with a difference in the dielectric constant between the film (A) and the film (B) being 0.3 or more The method for the formation of a stacked film according to the present invention comprises applying a coating solution comprising (B) a compound having a mean radius of gyration of less than 10 nm, the compound being obtained by hydrolysis and condensation of an alkoxysilane compound, and an organic solvent on a substrate, followed by drying; and then applying a coating solution comprising (A) a compound having a mean radius of gyration of from 10 to 30 nm, the compound being obtained by hydrolysis and condensation of an alkoxysilane compound, and an organic solvent on the substrate, followed by heating.
The insulating film according to the present invention comprises the stacked film.
The substrate for semiconductor according to the present invention comprises the insulating film.
DETAILED DESCRIPTION OF THE INVENTION
The alkoxysilane hydrolysis condensate as referred to in the present invention is one obtained by hydrolysis and. condensation of at least one alkoxysilane comprising a compound represented by the following general formula (1) (hereinafter, referred to as “compound (1)”), a compound represented by the following general formula (2) (hereinafter, referred as “compound (2)”), and a compound represented by the following general formula (3) (hereinafter, referred to as “compound (3)”):
R
a
Si(Or
1
)
4-a
(1)
wherein R represents a hydrogen atom, a fluorine atom, or a monovalent organic group; R
1
represents a monovalent organic group; and a represents an integer of 1 or 2;
Si(OR
2
)
4
(2)
wherein R
2
represents a monovalent organic group; and
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 represents a monovalent organic group;
b
and
c
may be the same or different and each represents a number of from 0 to 2; R
7
represents an oxygen atom, a phenylene group, or a group represented by —(CH
2
)
n
—, wherein n represents an integer of from 1 to 6; and d represents 0 or 1.
In the hydrolyzate as referred to in the present invention, it is not essential that all of the R
1
O— group, the R
2
O— group, the R
4
O— group, and the R
5
O— group contained in the compounds (1) to (3) are hydrolyzed. For example, the hydrolyzate may be one in which only one of the foregoing groups is hydrolyzed or one in which two or more of the foregoing groups are hydrolyzed, or a mixture thereof.
Further, in the condensate as referred to in the present invention, silanol groups in the hydrolyzates of the compound (1) to (3) are condensed to form Si—O—Si bonds. In the present invention, it is not essential that all of the silanol groups are condensed. The condensate includes one in which only a part of the silanol groups is condensed and a mixture of those having a different degree of condensation.
The alkoxysilane hydrolysis condensate is obtained by hydrolysis and condensation of at least one silane compound selected from the group consisting of the compounds (1) to (3) in the presence of a specific basic compound.
Compound (1):
In the foregoing general formula (1), examples of the monovalent organic group for R and R
1
include an alkyl group, an aryl group, an allyl group, and a glycidyl group. In the general formula (1), R is preferably a monovalent organic group, and especially an alkyl group or a phenyl group.
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group. The alkyl group preferably has from 1 to 5 carbon atoms and may be linear or branched. Further, the hydrogen atom(s) may be substituted with a fluorine atom.
In the general formula (1), examples of the aryl group include a phenyl group, a naphthyl group, a methylphenyl group, an ethylphenyl group, a chlorophenyl group, a bromophenyl group, and a fluorophenyl group.
Specific examples of the compound represented by the general formula (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,
Nishikawa Michinori
Sekiguchi Manabu
Shiota Atsushi
Yamada Kinji
Buttner David J.
JSR Corporation
Keehan Christopher
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