Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-12-22
2003-03-18
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S132000, C525S152000, C525S210000, C525S219000, C525S241000, C427S271000, C427S276000, C427S385500
Reexamination Certificate
active
06534595
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a porous organic film forming coating solution and a method for producing a porous organic film. Further, the present invention relates to a coating solution for forming a porous organic film suitable as an insulation film used in electronic devices, and a method for producing the porous organic film. More particularly, the present invention relates to a coating solution for forming a porous organic film suitable as an insulation film having low dielectric constant used in semiconductor parts, and a method for producing the porous organic film.
2. Description of the Related Art
In electronic parts, various insulation materials such as a layer insulation film, mold package material, wire coating material and the like are used. Recently, transferring speed of electron signals is respected for high speed communication, high speed processing and the like, and investigated from both of insulation material standpoint and wiring material standpoint. Particularly in LSI requiring high speed computing, signal transferring speed is important, and improvement in a process of producing a LSI itself and development of novel materials are flourishing. In the case of an insulation material, materials having lower dielectric constant, namely, materials having a relative dielectric constant of 3.0 or less, preferably 2.5 or less are required, for the purpose of securing high speed.
Relative dielectric constant is generally in proportion to the density and electron polarization nature of a material itself as represented by the formula of Clausis-Mosotti. Therefore, porous materials are respected for the purpose of decreasing relative dielectric constant by reduction of density. For example, JP-A Nos. 8-162450 and 10-70121 disclose a porous silica film obtained by conducting heat treatment under dry condition wherein shrinkage of an alkoxysilane is suppressed, and JP-A No. 9-315812 discloses a porous silica film obtained by mixing a colloidal silica with an alkoxysilane or a partial hydrolysis condensate and suppressing shrinkage ratio. However, a silica film gets increased surface area, further have enhanced water absorption and tends to manifest deteriorated dielectric constant by a porous structure, since water absorption of the film itself is remarkable. Consequently, surface hydrophobicizing treatment and the like are necessary, and throughput lowers.
While, an organic resin is a promising material for a porous structure since it has lower water absorption as compared with a silica film. A porous organic resin is already known as a construction material and insulation material, however, it can not get finer pore diameter due to use of a foaming agent. In the field of electronic parts, pore diameters of usually 0.3 &mgr;m or less, preferably 0.1 &mgr;m or less are required.
SUMMARY OR THE INVENTION
An object of the present invention is to provide a coating solution for forming a porous organic film which can get lower dielectric constant, as an insulation material usable in electronic parts, and a method for producing the porous organic film.
The present inventors have intensively studied a coating solution which can form a porous film usable in electronic devices, and a method for producing the porous organic film, and resultantly, found that a coating solution comprising a specific thermosetting resin, heat decomposable resin and organic solvent can be simply and conveniently coated on a substrate, and the heat decomposable resin can be decomposed to form uniformly fine cavity by conducting specific heat treatment, leading to completion of the present invention.
Namely, the present invention relates to a coating solution for forming a porous organic film comprising the following A) to C), wherein A) and B) have respective heat decomposition initiation temperatures Ta and Tb satisfying a relation: Ta>Tb:
A) a thermosetting resin having an aromatic ring in the main chain,
B) a heat decomposable resin obtained by polymerization of monomers which include at least one compound represented by the following formula (1) or (2), and
C) an organic solvent,
wherein, X represents an alkenyl group having 2 to 6 carbon atoms, each of R
1
to R
3
independently represents a hydrogen atom, or an alkyl group having 1 to 4 carbon atoms, and R
1
, R
2
and R
3
in the formula (1) may be different from R
1
, R
2
and R
3
in the formula (2), respectively.
The present invention also relates to a method for producing the porous organic film using the coating solution.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A) is a thermosetting resin having an aromatic ring in the main chain, and an insulation resin having a thermosetting functional group. As the thermosetting resin, there are specifically exemplified thermosetting resins wherein the main chain is formed by connecting a group having one or more aromatic rings selected from the group consisting of a benzene ring, biphenyl ring, terpheyl ring and triazine group which may be substituted, via one or more functional groups selected from the group consisting of a direct bond, alkylene groups having 1 to 20 carbon atoms, ether group, amide group, ester group, ketone group and sulfone group, and a functional group which causes an intra-molecular and/or inter-molecular crosslinking reaction is present at the side chain or the end of the main chain.
Among resins of A), a resin having in the main chain a structure in which an aromatic ring is connected via an ether bond is preferable since the resin itself has low dielectric constant and excellent insulation property, and further lower dielectric constant can be attained by a porous structure.
Further, among resins of A), a resin having in the resin main chain a unit structure of the formula (3) is preferable since it has excellent solubility in an organic solvent, manifests excellent coatibility, and has a relative dielectric constant of 3.5 or less:
wherein, each of L
1
to L
8
is independently selected from a hydrogen atom, chlorine atom, bromine atom, iodine atom, alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, alkynyl groups having 2 to 10 carbon atoms, cycloalkyl groups having 4 to 10 carbon atoms, methoxy group, ethoxy group, phenyl group which may be substituted, and functional groups of the following formula (4). A is selected from one or more of the following functional groups. Further, in the formula, B is selected from one or more of a single bond, hydrocarbon groups having 1 to 20 carbon atoms, ether group, ketone group and sulfone group.
wherein, each of Q
1
to Q
12
is independently selected from a hydrogen atom, alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, alkynyl groups having 2 to 10 carbon atoms, and functional groups of the following formula (4). Q
13
is selected from alkyl groups having 1 to 10 carbon atoms, alkenyl groups having 2 to 10 carbon atoms, and alkynyl groups having 2 to 10 carbon atoms. Y is selected from a hydrogen atom, fluorine atom, chlorine atom, bromine atom, iodine atom, —OZ
1
group, and —N(Z
2
) (Z
3
) group. Each of Z
1
to Z
3
is independently selected from a hydrogen atom, saturated or unsaturated hydrocarbon groups, and groups containing an ether bond.
—Si(T
1
)
n
(T
2
)
3-n
(4)
wherein, T
1
is selected from alkenyl groups having 2 to 10 carbon atoms. T
2
is selected from alkyl groups having 1 to 10 carbon atom, and arylene groups which may be substituted. n represents an integer of 1 to 3. T
1
s may be mutually different when n is 2 or 3, and T
2
s also may be mutually different when n is 1.
Specific examples of the group of the formula (4) include a vinyldimethylsilyl group, vinyldiethylsilyl group, vinylpropylsilyl group, vinyldiphenylsilyl group, vinyldinaphthylsilyl group, vinylmethylnaphthylsilyl group, vinylmethyethyllsilyl group, divinylethylpropylsilyl group, vinylpropylphenylsilyl group, divinylmethylphenylsilyl group, divinylmethylsilyl group, divinylethylsilyl group,
Choi Hyuncheol
Sukumoda Atsushi
Yoshida Yuji
Birch & Stewart Kolasch & Birch, LLP
Moore Margaret G.
Sumitomo Chemical Company Limited
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