Method of forming amorphous silica-based coating film with low dielectric constant and thus obtained silica-based coating film
First Claim
1. A method of forming an amorphous silica-based coating film with a low dielectric constant having a high film strength and excellent hydrophobic property and capable of ensuring smoothness of a surface coated therewith on a substrate comprising the steps of:
- (a) preparing a liquid composition containing a silicon compound obtained by hydrolyzing tetraalkyl ortho silicate (TAOS) and alkoxysilane (AS) expressed by the following general formula (I) in the presence of tetraalkyl ammonium hydroxide (TAAOH);
XnSi(OR)4-n
(I) wherein X indicates a hydrogen atom, a fluorine atom, or an alkyl group, a fluorine-substituted alkyl group, an aryl group or a vinyl group each having 1 to 8 carbon atoms;
R indicates a hydrogen atom, or an alkyl group, an aryl group or a vinyl group each having 1 to 8 carbon atoms; and
n is an integral number from 0 to 3. (b) applying the liquid composition on a substrate;
(c) heating the substrate at a temperature in a range from 80 to 350°
C.; and
(d) curing the substrate at a temperature in a range from 350 to 450°
C.
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Abstract
The present invention relates to an amorphous silica-based coating film with a low specific dielectric constant of 2.5 or below and the Young'"'"'s modulus of 6.0 GPa or more and having excellent hydrophobic property, and to a method of forming the same. A liquid composition containing a silicon compound obtained by hydrolyzing tetraalkyl ortho silicate (TAOS) and specific alkoxysilane (AS) in the presence of tetraalkyl ammonium hydroxide (TAAOH) is prepared. The liquid composition is then applied on a substrate, heated and cured to obtain a coating film. The coating film obtained as described has a smooth surface and also has specific micropores therein.
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Citations
17 Claims
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1. A method of forming an amorphous silica-based coating film with a low dielectric constant having a high film strength and excellent hydrophobic property and capable of ensuring smoothness of a surface coated therewith on a substrate comprising the steps of:
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(a) preparing a liquid composition containing a silicon compound obtained by hydrolyzing tetraalkyl ortho silicate (TAOS) and alkoxysilane (AS) expressed by the following general formula (I) in the presence of tetraalkyl ammonium hydroxide (TAAOH);
XnSi(OR)4-n
(I)wherein X indicates a hydrogen atom, a fluorine atom, or an alkyl group, a fluorine-substituted alkyl group, an aryl group or a vinyl group each having 1 to 8 carbon atoms;
R indicates a hydrogen atom, or an alkyl group, an aryl group or a vinyl group each having 1 to 8 carbon atoms; and
n is an integral number from 0 to 3.(b) applying the liquid composition on a substrate;
(c) heating the substrate at a temperature in a range from 80 to 350°
C.; and
(d) curing the substrate at a temperature in a range from 350 to 450°
C. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16, 17)
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2. A method of forming an amorphous silica-based coating film with a low dielectric constant having a high film strength and excellent hydrophobic property and capable of ensuring smoothness of a surface coated therewith on a substrate comprising the steps of:
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(a) preparing a liquid composition containing a silicon compound obtained by hydrolyzing or partially hydrolyzing tetraalkyl ortho silicate (TAOS) in the presence of tetraalkyl ammonium hydroxide (TAAOH), mixing the reaction product with the alkoxysilane (AS) expressed by the general formula (I) above or a hydrolysate or a partial hydrolysate thereof, and further hydrolyzing all or a portion of the mixture according to the necessity;
(b) applying the liquid composition on a substrate;
(c) heating the substrate at a temperature in a range from 80 to 350°
C.; and
(d) curing the substrate at a temperature in a range from 350 to 450°
C.
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14. The amorphous silica-based coating film with a low dielectric constant according to claim to 13, wherein said coating film contains pores having an average diameter of 3 nm or below and also with volume percentage of micropores each with the diameter of 2 nm or below of 70% or more.
Specification