JP2006183027A - Silica-based coating film-forming composition, method for forming silica-based coating film, the resultant silica-based coating film, and electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silica-based coating film-forming composition giving thick coating film. <P>SOLUTION: The silica-based coating film-forming composition comprises (a) 5-30 wt.% of a siloxane resin and (b) a solvent capable of dissolving the component(a), wherein the component(b) includes an aprotic solvent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a composition for forming a silica-based film, a method for forming a silica-based film, a silica-based film, and an electronic component.

Conventionally, a SiO ₂ film formed by a CVD method and having a relative dielectric constant of about 4.2 has been used as a material for forming an interlayer insulating film. However, from the viewpoint of reducing the inter-wiring capacitance of the device and improving the operation speed of the LSI, a material capable of developing a further low dielectric constant has been desired. In response to this demand, a SiOF film having a relative dielectric constant of about 3.5 and formed by a CVD method has been developed. Furthermore, organic SOG (Spin On Glass), an organic polymer, etc. were developed as an insulating material which has a dielectric constant of 2.5-3.0. Furthermore, a porous material having voids in the coating is considered to be effective as an insulating material having a relative dielectric constant of 2.5 or less, and studies and developments for application to an interlayer insulating film of LSI are actively conducted. ing.

As a method for forming such a porous material, Patent Documents 1 and 2 below propose a method using organic SOG. In this method, a composition containing a hydrolyzed polycondensation product of a metal alkoxide and a polymer having volatilization or decomposition characteristics is heated to form a film, and then the film is heated to form pores in the film. To obtain a porous material.
JP-A-11-322992 JP-A-11-310411

  In order to obtain a silica-based film having a thickness of 0.5 μm or more using these materials, it is considered effective to increase the concentration of the siloxane resin. However, the present inventors have found that storage stability is reduced and coating unevenness and repellency are generated by increasing the concentration of the siloxane resin, and the means for solving these problems have been studied.

  The present invention eliminates the above-mentioned drawbacks, and particularly provides a composition for forming a silica-based film that can be made thicker, a method for forming a silica-based film, a silica-based film, and an electronic component.

  The present invention is a composition for forming a silica-based film comprising a component (a): a siloxane resin, and a component (b): a solvent capable of dissolving the component (a), wherein the silica-based film is formed. A composition for forming a silica-based film in which the blending ratio of the component (a) in the composition for use is 5 to 30% by weight and the component (b) contains an aprotic solvent. By including this aprotic solvent, the composition for forming a silica-based film of the present invention can form a thick silica-based film and is useful for increasing the thickness of the silica-based film.

  Moreover, this invention provides the said composition for silica-type film formation whose compounding ratio of (a) component in the composition for silica-type film formation is 10 to 30 weight%. Such a composition for forming a silica-based film can form a thick silica-based film more easily.

  Moreover, this invention provides the said composition for silica-type film formation whose compounding ratio of (a) component in the composition for silica-type film formation is 15-25 weight%. Such a composition for forming a silica-based film can form a thick silica-based film even more easily.

  Further, in the present invention, from the viewpoint of facilitating the thickening of the film, the aprotic solvent is at least one selected from the group consisting of ether acetate solvents, ether solvents, and ketone solvents. The above-mentioned composition for forming a silica-based film comprising a solvent is provided.

  The present invention also provides the above-mentioned composition for forming a silica film, wherein the aprotic solvent contains an ether acetate solvent, from the viewpoint of more efficiently and reliably preventing coating unevenness and repellency.

  The present invention also relates to a method for forming a silica-based film on a substrate, wherein the silica-based film forming composition is applied onto a substrate to form a coating film, and an organic solvent contained in the coating film is removed. Provided is a method for forming a silica-based film in which the coating film is baked after removal. According to this forming method, it is possible to form a thick silica-based film using the silica-based film forming composition.

  Moreover, this invention provides the formation method of the said silica type coating film whose film thickness of a silica type coating film is 0.5-1.5 micrometers.

  Moreover, this invention provides the formation method of the said silica type coating film whose film thickness of a silica type coating film is 0.5-1.0 micrometer.

  Moreover, this invention is provided on the board | substrate and provides the silica type coating film formed by the formation method of the said silica type coating film. Such a silica-based film is a film that can be formed from the composition for forming a silica-based film.

  The present invention also provides an electronic component in which the silica-based film is formed on a substrate. Since the electronic component of the present invention includes a silica-based film that can be formed from a composition for forming a silica-based film even if it is a thick film, various characteristics depending on the silica-based film are good. For example, a silica-based film can be embedded in the recesses between the metal wirings of the electronic component, and the surface flatness can be improved. In addition, since the film thickness can be made uniform, variations in electrical characteristics of electronic components are reduced and optical characteristics are excellent.

  The composition for forming a silica-based film and the method for forming a silica-based film of the present invention can obtain a thick silica-based film and are useful for electronic parts.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  In the composition for forming a silica-based film of the present invention, one of the greatest technical features is that an aprotic solvent is included when the siloxane resin in the composition for forming a silica-based film is at a high concentration. This aprotic solvent is useful for thickening a silica-based coating.

  Another technical feature is that a protic solvent is included when the concentration of the siloxane resin in the composition for forming a silica-based film is high. This protic solvent is considered to be able to suppress the condensation reaction between SiOH groups which becomes a problem when the concentration of the siloxane resin is high. The inventors speculate that the SiOH group may be stabilized by hydrogen bonding with the protic solvent. I also think that it contributes to thickening.

  Still another technical feature is that a specific proportion of a curing accelerating catalyst is blended when the siloxane resin in the composition for forming a silica-based film is at a high concentration. By blending this curing accelerating catalyst in a specific ratio, it is useful for improving the storage stability of the silica-based film-forming composition. It is also useful for suppressing an increase in refractive index when used for display applications.

<(A) component>
The component (a) used in the present invention is a siloxane resin, and a known one can be used, but it is preferable to have an OH group (hydroxyl group) at the terminal or side chain of the resin. This is because the hydrolysis condensation reaction for curing the composition for forming a silica-based film is further advanced.

  The siloxane resin preferably has a weight average molecular weight (Mw) of 500 to 1,000,000, more preferably 500 to 500,000 from the viewpoints of solubility in a solvent, mechanical properties, moldability, and the like. More preferably, it is 100,000, particularly preferably 500-10000, and most preferably 500-5000. If the weight average molecular weight is less than 500, the film formability of the silica-based film tends to be inferior. If the weight average molecular weight exceeds 1000000, the compatibility with the solvent tends to be lowered. In the present specification, the weight average molecular weight is measured by gel permeation chromatography (hereinafter referred to as “GPC”) and converted using a standard polystyrene calibration curve.

The weight average molecular weight (Mw) can be measured, for example, by GPC under the following conditions.
Sample: 10 μL of silica-based film forming composition
Standard polystyrene: Standard polystyrene manufactured by Tosoh Corporation (molecular weight: 190000, 17900, 9100, 2980, 578, 474, 370, 266)
Detector: RI-monitor manufactured by Hitachi, Ltd., trade name “L-3000”
Integrator: GPC integrator manufactured by Hitachi, Ltd., trade name “D-2200”
Pump: manufactured by Hitachi, Ltd., trade name “L-6000”
Degassing device: Showa Denko Co., Ltd., trade name "Shodex DEGAS"
Column: Hitachi Chemical Co., Ltd., trade names “GL-R440”, “GL-R430”, “GL-R420” connected in this order and used as eluent: tetrahydrofuran (THF)
Measurement temperature: 23 ° C
Flow rate: 1.75 mL / min Measurement time: 45 minutes

As preferable siloxane resin, for example, the following general formula (1);
R ¹ _n SiX _4-n (1)
And a resin obtained by hydrolysis and condensation using the compound represented by formula (I) as an essential component. Here, in the formula, R ¹ is an H atom or F atom, or a group containing a B atom, an N atom, an Al atom, a P atom, a Si atom, a Ge atom, or a Ti atom, or an organic compound having 1 to 20 carbon atoms. X represents a hydrolyzable group, n represents an integer of 0 to 2, and when n is 2, each R ¹ may be the same or different, and when n is 0 to 2, X may be the same or different.

  Examples of the hydrolyzable group X include an alkoxy group, a halogen atom, an acetoxy group, an isocyanate group, and a hydroxyl group. Among these, an alkoxy group is preferable from the viewpoint of liquid stability of the composition itself, coating characteristics, and the like.

  As the compound (alkoxysilane) represented by the general formula (1) when the hydrolyzable group X is an alkoxy group, for example, tetraalkoxysilane, trialkoxysilane, dialkoxy, which may be substituted, respectively. Silane etc. are mentioned.

  Examples of the tetraalkoxysilane include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-iso-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, and tetra-tert-butoxysilane. Etc.

  Examples of the trialkoxysilane include trimethoxysilane, triethoxysilane, tripropoxysilane, fluorotrimethoxysilane, fluorotriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltri-n-propoxysilane, and methyltri-iso. -Propoxysilane, methyltri-n-butoxysilane, methyltri-iso-butoxysilane, methyltri-tert-butoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltri-n-propoxysilane, ethyltri-iso-propoxysilane, ethyltri N-butoxysilane, ethyltri-iso-butoxysilane, ethyltri-tert-butoxysilane, n-propyltrimethoxysilane, n-propyltrie Xysilane, n-propyltri-n-propoxysilane, n-propyltri-iso-propoxysilane, n-propyltri-n-butoxysilane, n-propyltri-iso-butoxysilane, n-propyltri-tert-butoxy Silane, iso-propyltrimethoxysilane, iso-propyltriethoxysilane, iso-propyltri-n-propoxysilane, iso-propyltri-iso-propoxysilane, iso-propyltri-n-butoxysilane, iso-propyltri -Iso-butoxysilane, iso-propyltri-tert-butoxysilane, n-butyltrimethoxysilane, n-butyltriethoxysilane, n-butyltri-n-propoxysilane, n-butyltri-iso-propoxysilane, n- Tiltly-n-butoxysilane, n-butyltri-iso-butoxysilane, n-butyltri-tert-butoxysilane, sec-butyltrimethoxysilane, sec-butyltriethoxysilane, sec-butyltri-n-propoxysilane, sec- Butyltri-iso-propoxysilane, sec-butyltri-n-butoxysilane, sec-butyltri-iso-butoxysilane, sec-butyltri-tert-butoxysilane, t-butyltrimethoxysilane, t-butyltriethoxysilane, t- Butyltri-n-propoxysilane, t-butyltri-iso-propoxysilane, t-butyltri-n-butoxysilane, t-butyltri-iso-butoxysilane, t-butyltri-tert-butoxysilane, phenyl Limethoxysilane, phenyltriethoxysilane, phenyltri-n-propoxysilane, phenyltri-iso-propoxysilane, phenyltri-n-butoxysilane, phenyltri-iso-butoxysilane, phenyltri-tert-butoxysilane, tri Examples include fluoromethyltrimethoxysilane, pentafluoroethyltrimethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, and 3,3,3-trifluoropropyltriethoxysilane.

  Examples of dialkoxysilane include dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldi-n-propoxysilane, dimethyldi-iso-propoxysilane, dimethyldi-n-butoxysilane, dimethyldi-sec-butoxysilane, and dimethyldi-tert-butoxy. Silane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldi-n-propoxysilane, diethyldi-iso-propoxysilane, diethyldi-n-butoxysilane, diethyldi-sec-butoxysilane, diethyldi-tert-butoxysilane, di-n- Propyldimethoxysilane, di-n-propyldiethoxysilane, di-n-propyldi-n-propoxysilane, di-n-propyldi-iso-propoxysilane, di-n-propisilane Di-n-butoxysilane, di-n-propyldi-sec-butoxysilane, di-n-propyldi-tert-butoxysilane, di-iso-propyldimethoxysilane, di-iso-propyldiethoxysilane, di-iso- Propyl di-n-propoxy silane, di-iso-propyl di-iso-propoxy silane, di-iso-propyl di-n-butoxy silane, di-iso-propyl di-sec-butoxy silane, di-iso-propyl di-tert-butoxy silane Di-n-butyldimethoxysilane, di-n-butyldiethoxysilane, di-n-butyldi-n-propoxysilane, di-n-butyldi-iso-propoxysilane, di-n-butyldi-n-butoxysilane Di-n-butyldi-sec-butoxysilane, di-n- Tildi-tert-butoxysilane, di-sec-butyldimethoxysilane, di-sec-butyldiethoxysilane, di-sec-butyldi-n-propoxysilane, di-sec-butyldi-iso-propoxysilane, di-sec- Butyldi-n-butoxysilane, di-sec-butyldi-sec-butoxysilane, di-sec-butyldi-tert-butoxysilane, di-tert-butyldimethoxysilane, di-tert-butyldiethoxysilane, di-tert- Butyldi-n-propoxysilane, di-tert-butyldi-iso-propoxysilane, di-tert-butyldi-n-butoxysilane, di-tert-butyldi-sec-butoxysilane, di-tert-butyldi-tert-butoxysilane , Diphenyl dimethoxy Sisilane, diphenyldiethoxysilane, diphenyldi-n-propoxysilane, diphenyldi-iso-propoxysilane, diphenyldi-n-butoxysilane, diphenyldi-sec-butoxysilane, diphenyldi-tert-butoxysilane, bis (3 , 3,3-trifluoropropyl) dimethoxysilane, methyl (3,3,3-trifluoropropyl) dimethoxysilane and the like.

The compound represented by the general formula where R ¹ is an organic group having 1 to 20 carbon atoms: (1) other than the above, for example, bis (trimethoxysilyl) methane, bis (triethoxysilyl ) Methane, bis (tri-n-propoxysilyl) methane, bis (tri-iso-propoxysilyl) methane, bis (trimethoxysilyl) ethane, bis (triethoxysilyl) ethane, bis (tri-n-propoxysilyl) Ethane, bis (tri-iso-propoxysilyl) ethane, bis (trimethoxysilyl) propane, bis (triethoxysilyl) propane, bis (tri-n-propoxysilyl) propane, bis (tri-iso-propoxysilyl) propane Bissilylalkane, bis (trimethoxysilyl) benzene, bis (triethoxysilyl) ) Bissilylbenzene such as benzene, bis (tri-n-propoxysilyl) benzene, bis (tri-iso-propoxysilyl) benzene, and the like.

The compound represented by the general formula where R ¹ is a group containing an Si atom (1), for example, hexamethoxydisilane, hexaethoxy disilane, hexa -n- propoxy disilanes, hexa -iso- propoxy disilane And hexaalkyldisilanes such as 1,2-dimethyltetramethoxydisilane, 1,2-dimethyltetraethoxydisilane, 1,2-dimethyltetrapropoxydisilane and the like.

  In addition, as the compound (halogenated silane) represented by the general formula (1) when the hydrolyzable group X is a halogen atom (halogen group), for example, the alkoxy group in each alkoxysilane molecule described above is a halogen atom. Examples thereof include those substituted with atoms. Further, as the compound (acetoxysilane) represented by the general formula (1) when the hydrolyzable group X is an acetoxy group, for example, the alkoxy group in each alkoxysilane molecule described above is substituted with an acetoxy group. And the like. Furthermore, as the compound (isocyanate silane) represented by the general formula (1) in the case where the hydrolyzable group X is an isocyanate group, for example, the alkoxy group in each alkoxysilane molecule described above is substituted with an isocyanate group. And the like. Furthermore, as the compound (hydroxysilane) represented by the general formula (1) when the hydrolyzable group X is a hydroxyl group, for example, the alkoxy group in each alkoxysilane molecule described above is substituted with a hydroxyl group. And the like.

  These compounds represented by the general formula (1) are used singly or in combination of two or more.

  Further, a resin obtained by hydrolytic condensation of a partial condensate such as a multimer of the compound represented by the general formula (1), a partial condensate such as a multimer of the compound represented by the general formula (1) and the general Resin obtained by hydrolytic condensation of the compound represented by formula (1), resin obtained by hydrolytic condensation of the compound represented by general formula (1) and other compounds, general formula (1) It is also possible to use a resin obtained by hydrolytic condensation of a partial condensate such as a multimer of the compound represented by general formula (1) and another compound.

  Examples of partial condensates such as multimers of the compound represented by the general formula (1) include hexamethoxydisiloxane, hexaethoxydisiloxane, hexa-n-propoxydisiloxane, hexa-iso-propoxydisiloxane, and the like. Examples include hexaalkoxydisiloxane, trisiloxane having advanced partial condensation, tetrasiloxane, and oligosiloxane.

  Examples of the “other compounds” include compounds having a polymerizable double bond or triple bond. Examples of the compound having a polymerizable double bond include ethylene, propylene, isobutene, butadiene, isoprene, vinyl chloride, vinyl acetate, vinyl propionate, vinyl caproate, vinyl stearate, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether. , Acrylonitrile, styrene, methacrylic acid, methyl methacrylate, ethyl methacrylate, methacrylate-n-propyl, methacrylate-iso-propyl, methacrylate-n-butyl, acrylic acid, methyl acrylate, ethyl acrylate, acrylic acid Examples thereof include phenyl, vinylpyridine, vinylimidazole, acrylamide, allylbenzene, diallylbenzene and the like, and those obtained by partial condensation of these compounds. Examples of the compound having a triple bond include acetylene and ethynylbenzene.

  The resins thus obtained are used alone or in combination of two or more.

  The amount of water used when hydrolyzing and condensing the compound represented by the general formula (1) is preferably 0.1 to 1000 mol, more preferably 1 mol per mol of the compound represented by the general formula (1). Is 0.5 to 100 mol. If the amount of water is less than 0.1 mol, the hydrolysis-condensation reaction tends not to proceed sufficiently, and if the amount of water exceeds 1000 mol, gelation tends to occur during hydrolysis or condensation.

  Moreover, it is also preferable to use a catalyst in the hydrolysis condensation of the compound represented by the general formula (1). Examples of such a catalyst include an acid catalyst, an alkali catalyst, and a metal chelate compound.

  Examples of the acid catalyst include organic acids and inorganic acids. Examples of organic acids include formic acid, maleic acid, fumaric acid, phthalic acid, malonic acid, succinic acid, tartaric acid, malic acid, lactic acid, citric acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid , Octanoic acid, nonanoic acid, decanoic acid, oxalic acid, adipic acid, sebacic acid, butyric acid, oleic acid, stearic acid, linoleic acid, linolenic acid, salicylic acid, benzenesulfonic acid, benzoic acid, p-aminobenzoic acid, p- Examples thereof include toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, trifluoroethanesulfonic acid, and the like. Examples of the inorganic acid include hydrochloric acid, phosphoric acid, nitric acid, boric acid, sulfuric acid, and hydrofluoric acid. Among these, maleic acid is preferable as the organic acid, and nitric acid is preferable as the inorganic acid. These are used singly or in combination of two or more.

  Examples of the alkali catalyst include inorganic alkalis and organic alkalis. Examples of the inorganic alkali include sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide and the like. Examples of the organic alkali include pyridine, monoethanolamine, diethanolamine, triethanolamine, dimethylmonoethanolamine, monomethyldiethanolamine, ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, methylamine, and ethylamine. Propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, cyclopentylamine, cyclohexylamine, N, N-dimethylamine, N, N-diethylamine, N , N-dipropylamine, N, N-dibutylamine, N, N-dipentylamine, , N-dihexylamine, N, N-dicyclopentylamine, N, N-dicyclohexylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, tricyclopentylamine, tricyclohexylamine, etc. It is done. These are used singly or in combination of two or more.

  The metal chelate compound is not particularly limited as long as it has a metal and a polydentate ligand, and may further have an organic group. Examples of the metal in the metal chelate compound include titanium, zirconium, aluminum and the like. Examples of the multidentate ligand include acetylacetonato ion and ethyl acetoacetate. Examples of the organic group include alkoxy groups such as a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, a sec-butoxy group, and a tert-butoxy group. Specific examples of the metal chelate compound include trimethoxy mono (acetylacetonato) titanium, triethoxy mono (acetylacetonato) titanium, tri-n-propoxy mono (acetylacetonato) titanium, tri-iso-propoxy mono (Acetylacetonato) titanium, tri-n-butoxy mono (acetylacetonato) titanium, tri-sec-butoxy mono (acetylacetonato) titanium, tri-tert-butoxy mono (acetylacetonato) titanium, dimethoxy Di (acetylacetonato) titanium, diethoxy-di (acetylacetonato) titanium, di-n-propoxy-di (acetylacetonato) titanium, diiso-propoxy-di (acetylacetonato) titanium, di-n-butoxy Di (acetylacetonato) titanium, dise -Butoxy di (acetylacetonato) titanium, ditert-butoxy di (acetylacetonato) titanium, monomethoxy tris (acetylacetonato) titanium, monoethoxy tris (acetylacetonato) titanium, mono n-propoxy Tris (acetylacetonato) titanium, monoiso-propoxy-tris (acetylacetonato) titanium, mono-n-butoxy-tris (acetylacetonato) titanium, mono-sec-butoxy-tris (acetylacetonato) titanium, mono-tert -Butoxy tris (acetylacetonato) titanium, tetrakis (acetylacetonato) titanium, trimethoxy mono (ethyl acetoacetate) titanium, triethoxy mono (ethyl acetoacetate) titanium, tri-n-propoxy mono (ethyl) Cetoacetate) titanium, tri-iso-propoxy mono (ethyl acetoacetate) titanium, tri-n-butoxy mono (ethyl acetoacetate) titanium, tri-sec-butoxy mono (ethyl acetoacetate) titanium, tri-tert -Butoxy mono (ethyl acetoacetate) titanium, dimethoxy di (ethyl acetoacetate) titanium, diethoxy di (ethyl acetoacetate) titanium, di-n-propoxy di (ethyl acetoacetate) titanium, diiso-propoxy di (Ethyl acetoacetate) titanium, di-n-butoxy di (ethyl acetoacetate) titanium, disec-butoxy di (ethyl acetoacetate) titanium, di tert-butoxy di (ethyl acetoacetate) titanium, monomethoxy tris (Ethyl acetoacetate) titanium, monoethoxy tris (ethyl acetoacetate) titanium, mono n-propoxy tris (ethyl acetoacetate) titanium, monoiso-propoxy tris (ethyl acetoacetate) titanium, mono n-butoxy tris (Ethyl acetoacetate) titanium, mono-sec-butoxy-tris (ethyl acetoacetate) titanium, mono-tert-butoxy-tris (ethyl acetoacetate) titanium, tetrakis (ethyl acetoacetate) titanium and other metal chelate compounds having the above, Examples thereof include compounds in which titanium of a metal chelate compound having titanium is replaced with zirconium, aluminum, or the like. These are used singly or in combination of two or more.

  When hydrolyzing and condensing the compound represented by the general formula (1), it is preferable to perform hydrolysis using such a catalyst. However, when the stability of the composition is deteriorated or the catalyst is contained, corrosion to other materials, etc. In some cases, the impact of In such a case, for example, after the hydrolysis, the catalyst may be removed from the composition, or may be reacted with another compound to deactivate the function as a catalyst. There are no particular restrictions on the method of removing the catalyst or the method of reacting, but the catalyst may be removed using distillation or an ion chromatography column. In addition, as a method of deactivating the function as a catalyst by reaction, for example, when the catalyst is an alkali catalyst, a method of adding an acid catalyst and neutralizing it by an acid-base reaction or bringing the pH to the acidic side can be mentioned. It is done. Similarly, when the catalyst is an acid catalyst, an alkali catalyst is added and neutralized by an acid-base reaction.

  The amount of the catalyst used is preferably in the range of 0.0001 to 1 mol with respect to 1 mol of the compound represented by the general formula (1). If the amount used is less than 0.0001 mol, the reaction does not proceed substantially, and if it exceeds 1 mol, gelation tends to be promoted during hydrolysis condensation.

  Furthermore, since the alcohol by-produced by this hydrolysis is a protic solvent, it is preferably removed using an evaporator or the like.

  The resin thus obtained preferably has a weight average molecular weight of 500 to 1,000,000, more preferably 500 to 500,000 from the viewpoints of solubility in a solvent, mechanical properties, moldability, and the like. More preferably, it is 100,000, particularly preferably 500-10000, and most preferably 500-5000. If the weight average molecular weight is less than 500, the film formability of the silica-based film tends to be inferior. If the weight average molecular weight exceeds 1000000, the compatibility with the solvent tends to be lowered.

When the composition for forming a silica-based film requires adhesion to the substrate on which it is applied and mechanical strength, H atoms bonded per 1 atom of Si atoms forming the siloxane bond of the siloxane resin , F atom, B atom, N atom, Al atom, P atom, Si atom, Ge atom, Ti atom and the total number of atoms selected from the group consisting of C atom (this is a specific bonding atom (general expression (1) the total number (M) of ^{R 1)} in.), is preferably from 1.30 to 0.20, more preferably 1.00 to 0.20, 0.90 It is especially preferable that it is -0.20, and it is very preferable that it is 0.80-0.20. If it does in this way, the fall to the adhesiveness to other films | membranes (layers) etc. of a silica-type film and mechanical strength can be suppressed.

  When the total number (M) of the specific bonding atoms is less than 0.20, the dielectric properties tend to be inferior when the silica-based coating is used as an insulating film, and when it exceeds 1.30, the finally obtained silica-based coating. The adhesiveness with other films (layers), mechanical strength, etc. tend to be inferior. Among the above-mentioned specific bonding atoms, at least one selected from the group consisting of H atoms, F atoms, N atoms, Si atoms, Ti atoms, and C atoms in terms of film-formability of the silica-based film. In view of dielectric properties and mechanical strength, at least one atom selected from the group consisting of H atom, F atom, N atom, Si atom and C atom is included. It is more preferable.

In addition, the total number (M) of a specific bond atom can be calculated | required from the preparation amount of a siloxane resin, for example, following formula (A);
M = (M1 + (M2 / 2) + (M3 / 3)) / Msi (A)
It can be calculated using the relationship represented by In the formula, M1 represents the total number of atoms bonded to a single (only one) Si atom among the specific bonded atoms, and M2 is bonded to two Si atoms among the specific bonded atoms. M3 represents the total number of atoms bonded to three Si atoms among the specific bonded atoms, and Msi represents the total number of Si atoms.

  Such siloxane resins are used alone or in combination of two or more. As a method of combining two or more types of siloxane resins, for example, a method of combining two or more types of siloxane resins having different weight average molecular weights, or two or more types of siloxane resins obtained by hydrolytic condensation using different compounds as essential components The method of combining, etc. are mentioned.

<(B) component>
The component (b) used in the present invention is a solvent that can dissolve the component (a). Examples of the solvent capable of dissolving the component (a) include aprotic solvents and protic solvents. These may be used alone or in combination of two or more.

  Examples of the aprotic solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-iso-propyl ketone, methyl-n-butyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, methyl-n- Hexyl ketone, diethyl ketone, dipropyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, acetonyl acetone, γ-butyrolactone, γ-valerolactone, etc. Ketone solvents; diethyl ether, methyl ethyl ether, methyl-n-di-n-propyl ether, di-iso-propyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyldioxane, ethyl Glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl mono-n-propyl ether, diethylene glycol methyl mono-n- Butyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di-n-butyl ether, diethylene glycol methyl mono-n-hexyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol methyl Non-n-butyl ether, triethylene glycol di-n-butyl ether, triethylene glycol methyl mono-n-hexyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetradiethylene glycol methyl ethyl ether, tetraethylene glycol methyl mono-n -Butyl ether, diethylene glycol di-n-butyl ether, tetraethylene glycol methyl mono-n-hexyl ether, tetraethylene glycol di-n-butyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol Dibutyl ether, dipropylene glycol dimethyl ether, Propylene glycol diethyl ether, dipropylene glycol methyl ethyl ether, dipropylene glycol methyl mono-n-butyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol methyl mono-n-hexyl Ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol methyl ethyl ether, tripropylene glycol methyl mono-n-butyl ether, tripropylene glycol di-n-butyl ether, tripropylene glycol methyl mono-n-hexyl ether, Tetrapropylene glycol dimethyl ether, tetrapropylene glycol diethyl ether, Ether type such as tetradipropylene glycol methyl ethyl ether, tetrapropylene glycol methyl mono-n-butyl ether, dipropylene glycol di-n-butyl ether, tetrapropylene glycol methyl mono-n-hexyl ether, tetrapropylene glycol di-n-butyl ether Solvent: methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, acetic acid Methylpentyl, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, nonyl acetate, methyl acetoacetate, ethyl acetoacetate, diethylene glycol monomethyl acetate Ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, glycol diacetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, Ester solvents such as i-amyl propionate, diethyl oxalate, di-n-butyl oxalate; ethylene glycol methyl ether propionate, ethylene glycol ethyl ether propionate, ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate , Diethylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol ether acetate solvents such as n-butyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, dipropylene glycol methyl ether acetate, dipropylene glycol ethyl ether acetate; acetonitrile, N-methylpyrrolidinone, N-ethylpyrrolidinone, N-propylpyrrolidinone, N-butylpyrrolidinone, N-hexylpyrrolidinone, N-cyclohexylpyrrolidinone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-dimethylsulfoxide and the like can be mentioned.

  Among these, from the viewpoint of increasing the film thickness, one or more solvents selected from the group consisting of ether solvents, ether acetate solvents, and ketone solvents are preferable. Furthermore, among these, from the viewpoint of suppressing coating unevenness and repellency, the first is an ether acetate solvent, the second is an ether solvent, and the third is a ketone solvent. These are used singly or in combination of two or more.

  Examples of protic solvents include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, and 2-methylbutanol. , Sec-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, n-octanol, 2-ethylhexanol, sec- Octanol, n-nonyl alcohol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexano , Benzyl alcohol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, and other alcohol solvents; ethylene glycol methyl ether, ethylene glycol ethyl ether , Ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-n-hexyl ether, ethoxytriglycol, tetraethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, di Propylene glycol monomethyl ether, dipropy Glycol monoethyl ether, ether solvents such as tripropylene glycol monomethyl ether; methyl lactate, ethyl lactate, n- butyl, ester solvents such as lactic acid n- amyl and the like.

  Of these, alcohol solvents are preferred from the viewpoint of storage stability. Among them, ethanol, isopropyl alcohol, propylene glycol propyl ether and the like are preferable from the viewpoint of suppressing coating unevenness and repellency.

  These are used singly or in combination of two or more.

  The proportion of the aprotic solvent is preferably 70% by weight to 90% by weight and more preferably 75% by weight to 85% by weight with respect to the total amount of solvent in the composition for forming a silica-based film. 73 wt% to 83 wt% is particularly preferable. If this blending ratio is less than 70% by weight, uneven coating tends to occur, and if it exceeds 90% by weight, the stability tends to decrease.

  The proportion of the protic solvent is preferably 0.1% by weight to 15% by weight, and preferably 0.5% by weight to 10% by weight, based on the total amount of the solvent in the composition for forming a silica-based film. More preferred is 1.0 to 7% by weight. If the blending ratio is less than 0.1% by weight, the stability tends to decrease, and if it exceeds 15% by weight, uneven coating tends to occur.

  The method of using the component (b) is not particularly limited. For example, the method of using the component (a) as a solvent when preparing the component, the method of adding the component after preparing the component (a), the method of exchanging the solvent, (a) Examples of the method include taking out the components by evaporating the solvent and adding (b) a solvent.

  Furthermore, the composition for forming a silica-based film of the present invention may contain water as necessary, but it is preferably within a range that does not impair the intended properties.

  The amount of these solvents used (total amount of aprotic solvent and protic solvent) is preferably such that the concentration of component (a) (siloxane resin) is 5 to 30% by weight. More preferably, the amount is ˜30% by weight, particularly preferably 13˜30% by weight, particularly preferably 15˜30% by weight, The amount is most preferably 15 to 25% by weight. When the amount of the solvent used is excessive and the concentration of the component (a) is less than 5% by weight, it tends to be difficult to form a silica-based film having a desired film thickness. When the amount of the solvent used is too small and the concentration of the component (a) exceeds 30% by weight, the film formability of the silica-based film is deteriorated and the stability of the composition itself tends to be lowered.

<(C) component>
The component (c) in the present invention is a curing accelerating catalyst and is different from a normal photoacid generator or photobase generator. Therefore, it is usually distinguished from onium salts such as those used as photoacid generators or photobase generators. However, any material that has both photoacid generation ability or photobase generation ability and curing acceleration catalytic ability can be used.

  This curing accelerating catalyst does not show a catalytic action in a solution, and is considered to be a unique one showing activity in a coated film.

Means for examining the curing acceleration catalytic ability of the curing acceleration catalyst are shown in 1-4 below.
1. First, a composition comprising the component (a) and the component (b) is prepared.
2. Then, the prepared composition is apply | coated on a silicon wafer so that the film thickness after baking (baking) may be set to 1.0 +/- 0.1 micrometer. Next, after the applied composition is baked at a predetermined temperature for 30 seconds, the film thickness of the resulting film is measured. At this time, the film thickness may be 1.0 ± 0.1 μm.
3. Next, the silicon wafer on which the film was formed was immersed in a 2.38 wt% tetramethylammonium hydroxide (TMAH) aqueous solution at 23 ± 2 ° C. for 30 seconds, further washed with water and dried, and the film thickness of the film was again increased. taking measurement. Under the present circumstances, let the minimum temperature at the time of baking the film thickness change of the film before and behind immersion in TMAH aqueous solution be less than 20% with respect to the film thickness before immersion to be insoluble temperature.
4). Next, a new composition is obtained by adding 0.01% by weight of the compound to be checked for the presence or absence of curing acceleration catalytic ability to the composition prepared in 1 above with respect to the total amount of component (a). The same treatment as in 2 and 3 above is performed to determine the insoluble temperature of the new composition.

  As a result, if the insoluble temperature of the composition is decreased by adding a compound for which the presence or absence of curing acceleration catalytic ability is to be confirmed, it is determined that the compound has curing acceleration catalytic ability.

  Examples of the curing accelerating catalyst that is component (c) include alkali metals having a curing accelerating catalytic ability such as sodium hydroxide, sodium chloride, potassium hydroxide, potassium chloride, and onium salts. These are used singly or in combination of two or more.

  Among these, from the viewpoint that the electrical properties and mechanical strength of the resulting silica-based coating can be improved, and further the stability of the composition can be improved, an onium salt having a curing promoting catalytic ability is preferable, and curing acceleration is achieved. A quaternary ammonium salt having catalytic ability is more preferable.

  As one of the onium salts, for example, a salt formed from a nitrogen-containing compound and at least one selected from an anionic group-containing compound and a halogen atom can be mentioned. The atom bonded to nitrogen of the nitrogen-containing compound is at least one selected from the group consisting of H atom, F atom, B atom, N atom, Al atom, P atom, Si atom, Ge atom, Ti atom and C atom. Are preferable. Examples of the anionic group include a hydroxyl group, a nitrate group, a sulfate group, a carbonyl group, a carboxyl group, a carbonate group, and a phenoxy group.

  Examples of onium salts include ammonium hydroxide, ammonium fluoride, ammonium chloride, ammonium bromide, ammonium iodide, ammonium phosphate salt, ammonium nitrate salt, ammonium borate salt, ammonium sulfate salt, ammonium formate salt, ammonium maleate salt, fumarate. Ammonium salt, ammonium phthalate, ammonium malonate, ammonium succinate, ammonium tartrate, ammonium malate, ammonium lactate, ammonium citrate, ammonium acetate, ammonium propionate, ammonium butanoate , Ammonium pentanoate, ammonium hexanoate, ammonium heptanoate, ammonium octanoate, ammonium nonanoate, Canoic acid ammonium salt, oxalic acid ammonium salt, adipic acid ammonium salt, sebacic acid ammonium salt, butyric acid ammonium salt, oleic acid ammonium salt, stearic acid ammonium salt, linoleic acid ammonium salt, linolenic acid ammonium salt, salicylic acid ammonium salt, benzenesulfone Ammonium salt, ammonium salt of benzoic acid, ammonium salt of p-aminobenzoic acid, ammonium salt of p-toluenesulfonic acid, ammonium salt of methanesulfonic acid, ammonium salt of trifluoromethanesulfonic acid, ammonium salt of trifluoroethanesulfonic acid, etc. Is mentioned.

  In addition, the ammonium ion of the ammonium salt is methylammonium ion, dimethylammonium ion, trimethylammonium ion, tetramethylammonium ion, ethylammonium ion, diethylammonium ion, triethylammonium ion, tetraethylammonium ion, propylammonium ion, dipropylammonium ion. , Ammonium salt substituted with tripropylammonium ion, tetrapropylammonium ion, butylammonium ion, dibutylammonium ion, tributylammonium ion, tetrabutylammonium ion, ethanolammonium ion, diethanolammonium ion, triethanolammonium ion, etc. It is done.

  In these onium salt compounds, ammonium such as tetramethylammonium nitrate, tetramethylammonium acetate, tetramethylammonium propionate, tetramethylammonium maleate, and tetramethylammonium sulfate is used from the viewpoint of accelerating the curing of the silica-based film. Salts are preferred.

  These are used singly or in combination of two or more.

  Moreover, it is preferable that the mixture ratio of (c) component is 0.0010-1.0 weight part with respect to 100 mass parts of (a) component in the composition for silica-type film formation, 0.0050 mass part More preferably, it is -1.0 mass part, and it is especially preferable that it is 0.0050-0.50 mass part. If the blending ratio is less than 0.0010 parts by mass, the curability tends to decrease, and the refractive index tends to increase when used for display applications, and if it exceeds 1.0 parts by mass, the storage stability decreases. Tend to.

  The onium salt can be adjusted to a desired concentration by dissolving or diluting in water or a solvent as necessary and then adding it to the silica-based film-forming composition. The timing of adding the onium salt to the composition for forming a silica-based film is not particularly limited. For example, when (a) the component is hydrolyzed, during hydrolysis, at the end of the reaction, before and after the solvent is distilled off, and acid is generated. It may be the time when the agent is added.

<Other ingredients>
Further, the composition for forming a silica-based film of the present invention is a range that does not impair the purpose and effect of the present invention, and further includes a dye, a surfactant, a silane coupling agent, a thickener, an inorganic filler, polypropylene glycol, and the like. A thermally decomposable compound, a volatile compound, or the like may be added. It is preferable that the thermally decomposable compound and the volatile compound are decomposed or volatilized by heat (preferably 250 to 500 ° C.) to form voids. Moreover, you may provide void | hole formation ability to the siloxane resin which is (a) component. Moreover, a photo-acid generator or a photobase generator can be contained and it can also be set as a radiation-curable composition.

  In addition, when using the composition for forming a silica-based film of the present invention for an electronic component, it is desirable not to contain an alkali metal or an alkaline earth metal, and even when it is contained, the metal ion concentration in the composition is 1000 ppm. Or less, more preferably 1 ppm or less. When these metal ion concentrations exceed 1000 ppm, metal ions easily flow into electronic components such as semiconductor elements having a silica-based film obtained from the composition, which may adversely affect device performance itself. Therefore, it is effective to remove alkali metal or alkaline earth metal from the composition using an ion exchange filter or the like, if necessary. However, when used for optical waveguides, other uses, etc., this is not limited as long as the purpose is not impaired.

  A method for forming a silica-based film on a substrate using such a composition for forming a silica-based film of the present invention will be described with reference to a spin coating method that is generally excellent in film formability and film uniformity. However, the silica-based film forming method is not limited to the spin coating method. Further, the substrate may be one having a flat surface or one having electrodes or the like and having irregularities. As these substrates, in addition to the above-mentioned substrates, organic polymers such as polyethylene terephthalate, polyethylene naphthalate, polyamide, polycarbonate, polyacryl, nylon (registered trademark), polyethersulfone, polyvinyl chloride, polypropylene, triacetyl cellulose, etc. Can be used. Also, plastic films such as organic polymers can be used.

  First, the composition for forming a silica-based film is spin-coated on a substrate such as a silicon wafer or a glass substrate, preferably at 300 to 3000 rotations / minute, more preferably at 400 to 2000 rotations / minute, to form a film. If the rotational speed is less than 300 revolutions / minute, the film uniformity tends to deteriorate, and if it exceeds 3000 revolutions / minute, the film formability may deteriorate.

  The film thickness of the silica-based film varies depending on the intended use. For example, the film thickness when used for an interlayer insulating film such as LSI is preferably 0.01 to 2 μm, and the film thickness when used for a passivation layer is 2 It is preferably ˜40 μm. Moreover, it is preferable that the film thickness at the time of using for a liquid crystal use is 0.1-20 micrometers, and it is preferable that the film thickness at the time of using for a photoresist is 0.1-2 micrometers, When using for an optical waveguide The film thickness is preferably 1 to 50 μm. Usually, this film thickness is generally preferably from 0.01 to 10 μm, more preferably from 0.01 to 5 μm, still more preferably from 0.01 to 3 μm, and preferably from 0.01 to 2 μm. Is particularly preferable, and it is very preferably 0.1 to 2 μm. The composition for forming a silica-based film of the present invention can be preferably used as a raw material for a silica-based film having a thickness of 0.5 to 2.0 μm, and has a thickness of 0.5 to 1.5 μm. It can be more preferably used as a raw material for the film, and can be particularly preferably used as a raw material for the silica-based film having a film thickness of 0.5 to 1.0 μm.

  In order to adjust the film thickness of the silica-based film, for example, the concentration of the component (a) in the composition for forming a silica-based film may be adjusted. Further, when the spin coating method is used, the film thickness can be adjusted by adjusting the number of rotations and the number of coatings. When the film thickness is controlled by adjusting the concentration of the component (a), for example, when increasing the film thickness, the concentration of the component (a) is increased, and when decreasing the film thickness, the component (a) It can be controlled by lowering the concentration of. In addition, when adjusting the film thickness by setting each condition of the spin coating method, for example, when increasing the film thickness, decreasing the number of rotations, increasing the number of applications, and reducing the film thickness Adjustments can be made by increasing the number of revolutions or reducing the number of applications.

  Next, the organic solvent in the coating film is dried on a hot plate or the like preferably at 50 to 350 ° C., more preferably at 100 to 300 ° C. If this drying temperature is less than 50 ° C., the organic solvent tends to be not sufficiently dried.

  Next, the coating film from which the organic solvent has been removed is baked at a heating temperature of 250 to 500 ° C. to perform final curing. In this manner, a silica-based film (Low-k film) that can exhibit a low dielectric constant even in a high-frequency region of 10 kHz or higher is formed. The “relative permittivity” in the present invention refers to a value measured in an atmosphere of 23 ° C. ± 2 ° C. and humidity of 40% ± 10%, and is preferably 2.5 or less. The relative dielectric constant is obtained, for example, by measuring the charge capacity between the Al metal and the N-type low resistivity substrate (Si wafer). The final curing is preferably performed in an inert atmosphere such as nitrogen, argon, helium, etc. In this case, the oxygen concentration is preferably 1000 ppm or less. If the heating temperature is less than 250 ° C., sufficient curing tends to be not achieved. If the heating temperature exceeds 500 ° C., if there is a metal wiring layer, the amount of heat input may increase and the wiring metal may be deteriorated. Therefore, it is preferable to perform final curing at a temperature of 450 ° C. or lower.

  Moreover, the heating time in the case of this hardening has preferable 2-60 minutes, and it is more preferable in it being 2-30 minutes. If this heating time exceeds 60 minutes, the amount of heat input may increase excessively and the wiring metal may deteriorate. As the heating device, it is preferable to use a heat treatment device such as a quartz tube furnace or other furnace, a hot plate, or a rapid thermal annealing (RTA) furnace.

  In addition, examples of the electronic component according to the present invention using the silica-based coating formed as described above include electronic devices having a silica-based coating such as semiconductor elements and multilayer wiring boards, and liquid crystal components. The silica-based film of the present invention can be used as a surface protective film (passivation film), a buffer coat film, an interlayer insulating film, and the like in a semiconductor element. On the other hand, in a multilayer wiring board, it can be suitably used as an interlayer insulating film.

  As semiconductor elements, for example, individual semiconductors such as diodes, transistors, compound semiconductors, thermistors, varistors, thyristors, DRAMs (dynamic random access memories), SRAMs (static random access memories), EPROMs (erasables) Programmable read-only memory (ROM), mask ROM (mask read-only memory), EEPROM (electrically erasable programmable read-only memory), memory elements such as flash memory, microprocessor, DSP, ASIC, etc. Theoretical circuit elements, integrated circuit elements such as compound semiconductors represented by MMIC (monolithic microwave integrated circuit), hybrid integrated circuits (hybrid IC), light emitting diodes De, and the like photoelectric conversion element such as a charge coupled device. Examples of the multilayer wiring board include a high-density wiring board such as MCM.

  When used for display applications such as liquid crystal parts, the refractive index of the silica-based film is preferably 1.35 or less, and more preferably 1.30 or less. Since the composition for forming a silica-based film of the present invention can form a silica-based film that can satisfy this refractive index requirement, it can be suitably used for display applications. For example, by providing irregularities on one surface of the substrate and forming a silica-based coating using the composition for forming a silica-based coating of the present invention on the other surface, oblique light incident from the end surface of the substrate is reflected. Light orthogonal to the silica-based coating surface can be extracted.

  FIG. 1 is a partial schematic cross-sectional view showing an embodiment of an electronic component according to the present invention. The CMOS logic device 100 (electronic component) includes a shallow junction portion 132, a channel 134, an element isolation portion 136, and a transistor 130 on a silicon substrate 105. Further thereon, the interlayer insulating films 122A, B, 120A to J, the etching preventing films 170A to F, the diffusion preventing insulating films 172A to 172E, the metal wiring 150A to E such as Cu and Al, the contact plug 152 and the via 154A. -E are provided. A passivation film 190 is further formed on the uppermost interlayer insulating film 120L and the metal wiring 150E among them.

  More specifically, an etching prevention film 170A is further laminated on the shallow junction 132, the channel 134, the element isolation part 136, and the interlayer insulating film 122A formed on the transistor 130, and a contact plug 152 penetrates through them. Is formed. A metal wiring 151 and an interlayer insulating film 122B formed between the metal wirings 151 are further provided thereon. These configurations 140 are sometimes referred to as local wirings, and are configured to connect the transistor 130 and the metal wiring 151 in the lowermost layer.

  On the local wiring 140, a diffusion preventing insulating film for preventing diffusion of the metal wiring material into the interlayer insulating film, etc., an interlayer insulating film for insulating between the metal wiring and the via, a via penetrating the via, an etching preventing film, and A metal wiring and an interlayer insulating film formed between the metal wirings are repeatedly laminated in order. Among them, several layers from the top (in FIG. 1, a structure comprising diffusion preventing insulating films 172D and E, interlayer insulating films 120G to J, vias 154D and E, etching preventing films 170E and F, and metal wirings 150D and E) 180 are , Sometimes referred to as global wiring, mainly plays a role of signal transmission between the functional blocks and connecting all the blocks in the CMOS logic device 100 as power supply and ground lines.

  A multilayer structure sandwiched between the local wiring 140 and the global wiring 180 (in FIG. 1, the diffusion preventing insulating films 172A to 172C, the interlayer insulating films 120A to 120F, the vias 154A to C, the etching preventing films 170B to D, and the metal wiring 150A to The configuration composed of C) 160 (referred to herein as “intermediate wiring”) mainly serves to connect the local wiring 140 and the global wiring 180. In the intermediate wiring 160, since there is a strong demand for increasing the signal transmission speed while miniaturizing the wiring, the silica-based coating of the present invention is preferably used as the interlayer insulating films 120A to 120F.

  Moreover, although it can be used also as uses, such as an optical waveguide, a use use is not this limitation.

  As described above, the silica-based coating formed by the composition for forming a silica-based coating according to the present invention is excellent in various properties and can cope with the increase in thickness, and can be suitably used for manufacturing electronic components.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

[Synthesis of siloxane resin]
(Synthesis Example 1)
In a solution prepared by dissolving 128.9 g of tetraethoxysilane and 100.5 g of methyltriethoxysilane in 452.7 g of propylene glycol methyl ether acetate, 67.9 g of nitric acid prepared to 0.644% by weight was stirred for 10 minutes. It was dripped over. After completion of dropping, the mixture was stirred and reacted for 3 hours. Next, part of the produced ethanol and propylene glycol methyl ether acetate was distilled off in a warm bath under reduced pressure to obtain 248.2 g of a siloxane resin A1 solution having a solid content concentration of 30.2% by weight. It was 870 when the weight average molecular weight of siloxane resin A1 was measured by GPC method.

(Synthesis Example 2)
In a solution prepared by dissolving 44.7 g of tetraethoxysilane and 34.8 g of methyltriethoxysilane in 156.9 g of methanol, 23.5 g of nitric acid prepared to 0.644% by weight was added dropwise over 10 minutes with stirring. . After completion of dropping, the mixture was stirred and reacted for 3 hours. Next, part of the generated ethanol and methanol was distilled off in a warm bath under reduced pressure to obtain 101.4 g of a solution of siloxane resin A2 having a solid content concentration of 25.6% by weight. It was 920 when the weight average molecular weight of siloxane resin A2 was measured by GPC method.

(Synthesis Example 3)
69.5 g of nitric acid prepared to 0.644% by weight was added dropwise over 10 minutes with stirring to a solution prepared by dissolving 143.9 g of tetraethoxysilane and 88.9 g of methyltriethoxysilane in 447.6 g of diethylene glycol dimethyl ether. did. After completion of dropping, the mixture was stirred and reacted for 3 hours. Subsequently, ethanol and a part of diethylene glycol dimethyl ether were distilled off in a warm bath under reduced pressure to obtain 245.8 g of a siloxane resin A3 solution having a solid content concentration of 30.5% by weight. It was 910 when the weight average molecular weight of siloxane resin A3 was measured by GPC method.

(Synthesis Example 4)
To a solution of 49.9 g of tetraethoxysilane and 30.8 g of methyltriethoxysilane dissolved in 155.2 g of ethylene glycol, 24.1 g of nitric acid prepared to 0.644% by weight was added dropwise over 10 minutes with stirring. did. After completion of dropping, the mixture was stirred and reacted for 3 hours. Subsequently, ethanol and a part of ethylene glycol were distilled off in a warm bath under reduced pressure to obtain 99.5 g of a siloxane resin A4 solution having a solid content concentration of 26.1% by weight. It was 940 when the weight average molecular weight of siloxane resin A4 was measured by GPC method.

[Preparation of silica-based film-forming composition]
Example 1
To 13.8 g of the solution of the siloxane resin A1 obtained in Synthesis Example 1, 74.4 g of propylene glycol methyl ether acetate (PGMEA), 1.2 g of polypropylene glycol (trade name “PPG725” manufactured by Aldrich), 2.38% 0.09 g of tetramethylammonium (TMA) nitrate aqueous solution (pH 3.6) and 0.45 g of 1% maleic acid aqueous solution were added, respectively, and stirred and dissolved at room temperature (25 ° C.) for 30 minutes to obtain a siloxane resin and polypropylene glycol. 90.0 g of a composition for forming a silica-based film having a solid concentration of 6% by weight was obtained.

(Examples 2-8, Comparative Examples 1-8)
A composition for forming a silica-based film was obtained in the same manner as in Example 1 except that the type and blending amount of each component were changed as shown in Tables 1 and 2. The weight and siloxane resin (solid content) concentration of the resulting silica-based film forming composition are shown in Tables 1 and 2. In Tables 1 and 2, “DEGDME” represents diethylene glycol dimethyl ether.

[Formation of silica-based film]
The composition for forming a silica-based film of each Example and Comparative Example was spin-coated on a silicon wafer at a rotation speed of 1000 rpm for 30 seconds. After spin coating, the solvent was removed in a 250 ° C. environment for 3 minutes, and the coating film was finally cured in a quartz tube furnace in which the O ₂ concentration was controlled at around 100 ppm in a 400 ° C. environment for 30 minutes.

[Film evaluation]
(Evaluation of applicability)
The state of the coating film immediately after the spin coating was visually observed. "A" when the coating unevenness is not recognized and the coating property is good, "B" when the coating unevenness is large, "C1" when the film thickness is thin and many coating unevenness is recognized, The case where cracks occurred in the coating film and whitening was observed was evaluated as “C2”. The results are shown in Tables 3 and 4. In the table, “below the lower limit” means that the film thickness and refractive index could not be measured because the film thickness was less than 100% of the measurement limit. Further, “not measurable” means that the measurement was not possible because a crack occurred.

(Measurement of film thickness and refractive index)
After the formation of the silica-based film, the film thickness and refractive index were measured with an ellipsometer. The results are shown in Tables 3 and 4.

(Reference example)
To a solution obtained by dissolving 515.5 g of tetraethoxysilane and 402.0 g of methyltriethoxysilane in 1854.5 g of diethylene glycol dimethyl ether, 1.3 g of a 2.38 wt% tetramethylammonium nitrate aqueous solution (pH 3.6) was added. did. Next, 271.7 g of nitric acid prepared to 0.644% by weight was added dropwise over 30 minutes with stirring. After completion of dropping, the mixture was stirred and reacted for 3 hours. Subsequently, ethanol and a part of diethylene glycol dimethyl ether were distilled off in a warm bath under reduced pressure to obtain 1681.9 g of a siloxane resin solution.

  To 1681.9 g of this siloxane resin solution were added 128.7 g of diethylene glycol dimethyl ether, 88.1 g of polypropylene glycol (trade name “PPG725” manufactured by Aldrich) and 100.0 g of ethanol, respectively, and stirred at room temperature (25 ° C.) for 30 minutes. It melt | dissolved and the composition for silica-type film formation was obtained. It was 870 when the weight average molecular weight of the siloxane resin was measured by GPC method.

  The resulting composition for forming a silica-based film was able to sufficiently form a silica-based film even with a film thickness of 0.5 μm, which is twice or more the conventional film thickness (0.2 μm).

1 is a schematic cross-sectional view showing a preferred embodiment of an electronic component according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... CMOS logic device, 105 ... Silicon substrate, 120A-L, 122A, B ... Interlayer insulation film, 130 ... Transistor, 132 ... Shallow junction part, 134 ... Channel, 136 ... Element isolation part, 140 ... Local wiring, 150A- E, 151 ... Metal wiring, 152 ... Contact plug, 154A to E ... Via, 160 ... Intermediate wiring, 170A-F ... Etching prevention film, 172A-E ... Diffusion prevention insulating film, 180 ... Global wiring, 190 ... Passivation film.

Claims (10)

(A) component: a siloxane resin, and (b) component: a composition for forming a silica-based film comprising a solvent capable of dissolving the component (a),
The composition for forming a silica-based film, wherein the blending ratio of the component (a) in the composition for forming a silica-based film is 5 to 30% by weight, and the component (b) includes an aprotic solvent.   The composition for forming a silica-based film according to claim 1, wherein a blending ratio of the component (a) in the composition for forming a silica-based film is 10 to 30% by weight.   The composition for forming a silica-based film according to claim 1, wherein a blending ratio of the component (a) in the composition for forming a silica-based film is 15 to 25% by weight.   The silica according to any one of claims 1 to 3, wherein the aprotic solvent includes one or more solvents selected from the group consisting of ether acetate solvents, ether solvents, and ketone solvents. -Based film-forming composition.   The composition for forming a silica-based film according to any one of claims 1 to 3, wherein the aprotic solvent contains an ether acetate solvent.   A method for forming a silica-based film on a substrate, wherein the composition for forming a silica-based film according to any one of claims 1 to 5 is applied on a substrate to form a coating film, and the coating film A method for forming a silica-based coating comprising removing the organic solvent contained in the coating and then firing the coating film.   The method for forming a silica-based coating according to claim 6, wherein the thickness of the silica-based coating is 0.5 to 1.5 μm.   The method for forming a silica-based coating according to claim 6, wherein the thickness of the silica-based coating is 0.5 to 1.0 μm.   A silica-based coating provided on a substrate and formed by the method for forming a silica-based coating according to any one of claims 6 to 8.   An electronic component comprising the substrate and the silica-based film according to claim 9 formed thereon.

Images