JP2006213908A - Composition for forming silica-based film, method for forming silica-based film, silica-based film and electronic part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for forming a silica-based film having excellent surface smoothness as compared with conventional ones. <P>SOLUTION: The composition for forming a silica-based film comprises (a) a siloxane resin, (b) a solvent capable of dissolving the ingredient (a) and (c) an onium salt, wherein the ratio of the above ingredient (c) to be incorporated is 0.001 to 0.5 pt.wt. relative to 100 pts.wt. of the total amount of the above ingredient (a). <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.

  Along with miniaturization of wiring due to high integration of LSI, there is a problem of increase in signal delay time due to increase in inter-wiring capacitance. In addition to heat resistance, mechanical properties, etc., insulating materials for electronic components are low dielectric constants. The rate and shortening of the heat treatment process are required.

In general, the signal propagation speed (v) of the wiring and the dielectric constant (ε) of the insulating material in contact with the wiring material have a relationship represented by v = k / √ε (k is a constant), and the signal propagation speed. In order to increase the speed, it is necessary to increase the frequency region to be used and to lower the relative dielectric constant of the insulating material at that time. Conventionally, a SiO ₂ film by a CVD method having a relative dielectric constant of about 4.2 has been used as an interlayer insulating material. However, in order to reduce the inter-device capacitance and improve the operation speed of the LSI, a lower dielectric constant is used. Materials are needed. An example of a low dielectric constant material currently in practical use is a SiOF film (CVD method) having a relative dielectric constant of about 3.5. As an insulating material having a relative dielectric constant of 2.5 to 3.0, organic SOG (Spin On Glass), an organic polymer, etc., and as an insulating material having a relative dielectric constant of 2.5 or less, a porous material having voids in the film Is considered promising, and studies for applying it to an interlayer insulating film of LSI are being actively conducted.

  Among them, as a method for forming a porous material, a reduction in dielectric constant of an organic SOG material has been proposed, and a coating is formed from a composition containing a hydrolytic condensation polymer of metal alkoxysilane and a polymer that volatilizes or decomposes upon heating. It has been proposed to form a film material having excellent low dielectric properties by forming pores by forming and heating (see, for example, Patent Document 1 and Patent Document 2). However, these methods have a great problem in process adaptability because the film strength is lowered as the dielectric constant is reduced.

  On the other hand, when the wiring material is Al, the method for forming the interlayer insulating film is a method of forming an insulating film after forming the Al wiring, and therefore an insulating material having a feature of filling the recesses between the wirings flatly without gaps is required. Yes.

  Conventionally, as a flattening technique for eliminating such a step in the concave portion, for example, a method using an organic material such as a silicon ladder, polyimide, or polyimide silicone is known. However, films obtained from these organic materials have the disadvantages that they are easily pyrolyzed at a temperature of about 300 to 450 ° C. and have poor heat resistance, moisture resistance, and the like.

  In addition, a so-called bias sputtering method is known in which a film is formed while the substrate is lightly tapped with charged particles so that the substrate does not contain residual gases such as hydrogen, oxygen, and nitrogen. This method is suitable for flattening in a fine portion, but has a drawback of damaging the underlying substrate during the film accumulation process.

In addition, a silanol and an alkylsilanol are dissolved in an organic solvent to prepare a coating solution, and this coating solution is applied so as to fill the recesses between the wirings and cover the entire surface of the base substrate, and then a silica-based coating by heat treatment. In general, a so-called spin-on-glass method (SOG coating method) for forming and flattening the film is put into practical use. However, the conventional silica-based coating is an insulating material having a relative dielectric constant of about 3.0, and a material having a lower dielectric constant is required to improve the operation speed of LSI.
JP-A-11-310411 JP-A-11-322992

  When the present inventors applied a silica-based film-forming composition containing an onium salt in a specific blending ratio to a substrate having irregularities on the surface, the onium salt was contained in a blending ratio other than the specific blending ratio. The present inventors have found that the flatness of the obtained silica-based coating is improved as compared with the composition for forming a silica-based coating, and have reached the present invention. An important point of the present invention is that the mixing ratio of the onium salt is set to a specific mixing ratio.

  The present invention relates to a composition for forming a silica-based film capable of forming a silica-based film having excellent flatness as compared with the prior art, a silica-based film obtained therefrom, a method for forming the same, and the silica-based film It aims at providing an electronic component provided with.

  The present invention is a silica-based film-forming composition comprising (a) a siloxane resin, (b) a solvent capable of dissolving the component (a), and (c) an onium salt, The composition for forming a silica-based film in which the blending ratio of the component is 0.001 to 0.5 parts by weight with respect to 100 parts by weight of the total amount of the component (a).

Moreover, this invention is the following general formula (1) as (a) siloxane resin;
R ¹ _n SiX _4-n (1)
(In the formula, R ¹ represents an H atom or F atom, or a group containing B atom, N atom, Al atom, P atom, Si atom, Ge atom or Ti atom, or an organic group 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, each X is the same But it may be different.)
The above-mentioned composition for forming a silica-based film comprising a resin obtained by hydrolytic condensation of a compound represented by the formula:

  Further, the present invention provides (a) siloxane resin as H atom, F atom, B atom, N atom, Al atom, P atom bonded per one atom of Si atom forming the siloxane bond of the siloxane resin. Provided is the above-mentioned composition for forming a silica-based film, comprising a resin having a total number of at least one atom selected from the group consisting of atoms, Si atoms, Ge atoms, Ti atoms and C atoms being 0.65 or less.

  Moreover, this invention provides the said composition for silica-type film formation whose compounding ratio of (c) onium salt is 0.001-0.4 weight part with respect to 100 weight part of total amounts of the said (a) component. .

  Moreover, this invention provides the said composition for silica-type film formation whose compounding ratio of (c) onium salt is 0.001-0.3 weight part with respect to 100 weight part of total amounts of the said (a) component. .

  Moreover, this invention provides the said composition for silica-type film formation whose compounding ratio of (c) onium salt is 0.001-0.2 weight part with respect to 100 weight part of total amounts of the said (a) component. .

  Moreover, this invention provides the said composition for silica type film formation whose compounding ratio of (c) onium salt is 0.001-0.1 weight part with respect to 100 weight part of total amounts of the said (a) component. .

  Moreover, this invention provides the said composition for silica-type film formation whose compounding ratio of (c) onium salt is 0.01-0.1 weight part with respect to 100 weight part of total amounts of said (a) component. .

  Moreover, this invention provides the said composition for silica-type film formation apply | coated on the board | substrate which has an unevenness | corrugation on the surface.

  The present invention also relates to a method for forming a silica-based film on a substrate, wherein the above-mentioned composition for forming a silica-based film is applied onto a substrate to form a coating film, and an organic solvent contained in the coating film A method of forming a silica-based coating is provided in which the coating film is baked after removing.

  Moreover, this invention provides the formation method of the said silica-type film in which the surface of the board | substrate which apply | coats the composition for silica-type film formation has an unevenness | corrugation.

  Moreover, this invention is provided on the board | substrate and provides the silica-type film formed by the formation method of the above-mentioned silica-type film.

  The present invention also provides an electronic component in which the above silica-based film is formed on a substrate.

  INDUSTRIAL APPLICABILITY The composition for forming a silica-based film and the method for forming a silica-based film of the present invention can form a silica-based film that is superior in flatness as compared with the prior art, 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.

<(A) component>
The component (a) is a siloxane resin, and a known one can be used, but it is preferable to have an OH group at the end 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 20,000, preferably 1,000 to 10,000 from the viewpoints of solubility in a solvent, mechanical properties, moldability, and the like. And more preferred. When the weight average molecular weight is less than 500, the film-forming property of the silica-based film tends to be inferior. When the weight average molecular weight exceeds 20,000, 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.

  Examples of the compound (alkoxysilane) of the general formula (1) in which the hydrolyzable group X is an alkoxy group include tetraalkoxysilane, trialkoxysilane, and diorganodialkoxysilane.

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

  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, methyltriphenoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltri-n-propoxysilane, ethyltri-iso -Propoxysilane, ethyltri-n-butoxysilane, ethyltri-iso-butoxysilane, ethyltri-tert-butoxysilane, ethyltriphenoxy N-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltri-n-propoxysilane, n-propyltri-iso-propoxysilane, n-propyltri-n-butoxysilane, n-propyltri -Iso-butoxysilane, n-propyltri-tert-butoxysilane, n-propyltriphenoxysilane, iso-propyltrimethoxysilane, iso-propyltriethoxysilane, iso-propyltri-n-propoxysilane, iso-propyl Tri-iso-propoxysilane, iso-propyltri-n-butoxysilane, iso-propyltri-iso-butoxysilane, iso-propyltri-tert-butoxysilane, iso-propyltriphenoxysilane, n-butyltrimethyl Xylsilane, n-butyltriethoxysilane, n-butyltri-n-propoxysilane, n-butyltri-iso-propoxysilane, n-butyltri-n-butoxysilane, n-butyltri-iso-butoxysilane, n-butyltri-tert -Butoxysilane, n-butyltriphenoxysilane, sec-butyltrimethoxysilane, sec-butyltriethoxysilane, sec-butyltri-n-propoxysilane, sec-butyltri-iso-propoxysilane, sec-butyltri-n-butoxy Silane, sec-butyltri-iso-butoxysilane, sec-butyltri-tert-butoxysilane, sec-butyltriphenoxysilane, t-butyltrimethoxysilane, t-butyltriethoxysilane, t-butylto Ri-n-propoxysilane, t-butyltri-iso-propoxysilane, t-butyltri-n-butoxysilane, t-butyltri-iso-butoxysilane, t-butyltri-tert-butoxysilane, t-butyltriphenoxysilane, Phenyltrimethoxysilane, phenyltriethoxysilane, phenyltri-n-propoxysilane, phenyltri-iso-propoxysilane, phenyltri-n-butoxysilane, phenyltri-iso-butoxysilane, phenyltri-tert-butoxysilane, Phenyltriphenoxysilane, trifluoromethyltrimethoxysilane, pentafluoroethyltrimethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxy Run, and the like.

  Examples of the diorganodialkoxysilane include dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldi-n-propoxysilane, dimethyldi-iso-propoxysilane, dimethyldi-n-butoxysilane, dimethyldi-sec-butoxysilane, and dimethyldi-tert. -Butoxysilane, dimethyldiphenoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldi-n-propoxysilane, diethyldi-iso-propoxysilane, diethyldi-n-butoxysilane, diethyldi-sec-butoxysilane, diethyldi-tert- Butoxysilane, diethyldiphenoxysilane, di-n-propyldimethoxysilane, di-n-propyldiethoxysilane, di-n-propyldi-n-propoxy Di-n-propyldi-iso-propoxysilane, di-n-propyldi-n-butoxysilane, di-n-propyldi-sec-butoxysilane, di-n-propyldi-tert-butoxysilane, di-n- Propyl diphenoxy silane, di-iso-propyl dimethoxy silane, di-iso-propyl diethoxy silane, di-iso-propyl di-n-propoxy silane, di-iso-propyl di-iso-propoxy silane, di-iso-propyl di- n-butoxysilane, di-iso-propyldi-sec-butoxysilane, di-iso-propyldi-tert-butoxysilane, di-iso-propyldiphenoxysilane, di-n-butyldimethoxysilane, di-n-butyldi Ethoxysilane, di-n-butyldi-n-propoxy Silane, di-n-butyldi-iso-propoxysilane, di-n-butyldi-n-butoxysilane, di-n-butyldi-sec-butoxysilane, di-n-butyldi-tert-butoxysilane, di-n- Butyldiphenoxysilane, 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-sec-butyldiphenoxysilane, di-tert-butyldimethoxysilane, di-tert-butyldi Ethoxysilane, di-tert-butyldi-n-propoxysila Di-tert-butyldi-iso-propoxysilane, di-tert-butyldi-n-butoxysilane, di-tert-butyldi-sec-butoxysilane, di-tert-butyldi-tert-butoxysilane, di-tert- Butyldiphenoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldi-n-propoxysilane, diphenyldi-iso-propoxysilane, diphenyldi-n-butoxysilane, diphenyldi-sec-butoxysilane, diphenyldi-tert -Butoxysilane, diphenyldiphenoxysilane, bis (3,3,3-trifluoropropyl) dimethoxysilane, methyl (3,3,3-trifluoropropyl) dimethoxysilane and the like.

In addition, the compound of the general formula (1) in which R ¹ is an organic group having 1 to 20 carbon atoms, and other compounds than the above include, 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, bis (tri Methoxysilyl) benzene, bis (triethoxysilyl) benzene, bis (tri-n-pro Examples thereof include bissilylalkanes such as (poxysilyl) benzene and bis (tri-iso-propoxysilyl) benzene, and bissilylbenzene.

Examples of the compound of the general formula (1) in which R ¹ is a group containing Si atom include hexaalkoxydisilanes such as hexamethoxydisilane, hexaethoxydisilane, hexa-n-propoxydisilane, and hexa-iso-propoxydisilane. And dialkyltetraalkoxydisilanes such as 1,2-dimethyltetramethoxydisilane, 1,2-dimethyltetraethoxydisilane, 1,2-dimethyltetrapropoxydisilane, and the like.

  Moreover, as a compound (halogenated silane) of General formula (1) whose hydrolyzable group X is a halogen atom (halogen group), the alkoxy group in each alkoxysilane molecule mentioned above is substituted with a halogen atom, for example. And the like. Furthermore, examples of the compound (acetoxysilane) of the general formula (1) in which the hydrolyzable group X is an acetoxy group include those in which the alkoxy group in each alkoxysilane molecule described above is substituted with an acetoxy group. It is done. Furthermore, examples of the compound (isocyanate silane) of the general formula (1) in which the hydrolyzable group X is an isocyanate group include those in which the alkoxy group in each alkoxysilane molecule described above is substituted with an isocyanate group. Can be mentioned. Furthermore, examples of the compound (hydroxysilane) of the general formula (1) in which the hydrolyzable group X is a hydroxyl group include those in which the alkoxy group in each alkoxysilane molecule described above is substituted with a hydroxyl group. Can be mentioned.

  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, particularly preferably 0.5 to 20 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. 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.

  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.

  In the hydrolytic condensation of the compound represented by the general formula (1), it is preferable to carry out 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 is no particular limitation on the method of removing or reacting, but it may be removed using distillation, ion chromatography column or the like. Moreover, the hydrolyzate obtained from the compound represented by the general formula (1) may be taken out of the composition by reprecipitation or the like. 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.

  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 (Mw) of 500 to 20,000 from the viewpoint of solubility in a solvent, mechanical properties, moldability, etc., and 1,000 to 10,000. 000 is more preferable. When the weight average molecular weight is less than 500, the film-forming property of the silica-based film tends to be inferior. When the weight average molecular weight exceeds 20,000, the compatibility with the solvent tends to be lowered.

When adhesion to the substrate and mechanical strength are required, H atom, F atom, B atom, N atom, Al atom, P atom, Si atom, Ge atom with respect to 1 mol of Si atom in the general formula (1) , A total content of at least one atom selected from the group consisting of Ti atoms and C atoms, that is, H atoms, F atoms bonded per one atom of Si atoms forming the siloxane bond of the siloxane resin, Total number of at least one atom selected from the group consisting of B atom, N atom, Al atom, P atom, Si atom, Ge atom, Ti atom and C atom (this is a specific bonding atom (general formula (1) The total number (R) of R ¹ ) is preferably 0.65 or less, more preferably 0.55 or less, particularly preferably 0.50 or less. 45 or less Highly preferred. This lower limit is about 0.20. If it does in this way, the adhesiveness to the other film | membrane (layer) of a silica-type film and the fall of 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 film is used as an insulating film, and when it exceeds 0.65, the silica-based film finally obtained 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 = (M 1 + M 2} /2) + (M 3/3)) / M si (A)
It can be calculated using the relationship represented by In the formula, M ₁ represents the total number of atoms bonded to a single (only one) Si atom among the specific bonded atoms, and M ₂ is bonded to two silicon atoms among the specific bonded atoms. M ₃ represents the total number of atoms bonded to three silicon atoms among the specific bonded atoms, and M _si represents the total number of Si atoms.

For example, the value of M of the resin hydrolyzed and condensed by charging 154.6 g of tetraethoxysilane (TEOS) and 120.6 g of methyltriethoxysilane (MTES) is as follows.
TEOS charge 154.6g
MTES preparation amount 120.6g
TEOS molecular weight 208.3 g / mol
MTES molecular weight 178.3 g / mol
M = {(120.6 / 178.3) × 6.02 × 10 ²³ } / {(154.6 / 208.3) + (120.6 / 178.3) × 6.02 × 10 ²³ } = 0.48

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

  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) There is a method in which components are taken out by solvent distillation or the like and (b) a solvent is added.

  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 blending ratio of this solvent (total of aprotic solvent and protic solvent) is the concentration of (a) component (siloxane resin) (((a) component / ((a) component + (b) component)) × 100) is preferably 3 to 25% by weight. When the blending ratio of the solvent is less than 3% by weight, the stability and film formability tend to be inferior, and when it exceeds 25% by weight, it is difficult to obtain a desired film thickness.

<(C) component>
Examples of the onium salt compound include a salt formed from (d-1) a nitrogen-containing compound and (d-2) at least one selected from an anionic group-containing compound and a halogen atom. The atoms bonded to nitrogen of the above (d-1) nitrogen-containing compound are composed of H atom, F atom, B atom, N atom, Al atom, P atom, Si atom, Ge atom, Ti atom, and C atom. It is preferably at least one selected from the group. 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 these onium salt compounds include ammonium hydroxide, ammonium fluoride, ammonium chloride, ammonium bromide, ammonium iodide, ammonium phosphate, ammonium nitrate, ammonium borate, ammonium sulfate, ammonium formate, and ammonium maleate. , Ammonium fumarate, ammonium phthalate, ammonium malonate, ammonium succinate, ammonium tartrate, ammonium malate, ammonium lactate, ammonium citrate, ammonium acetate, ammonium propionate, butanoic acid Ammonium salt, ammonium pentanoate, ammonium hexanoate, ammonium heptanoate, ammonium octanoate, ammonium nonanoate Nium salt, ammonium decanoate, ammonium oxalate, ammonium adipate, ammonium sebacate, ammonium butyrate, ammonium oleate, ammonium stearate, ammonium linoleate, ammonium linolenate, ammonium salicylate Benzene sulfonic acid ammonium salt, benzoic acid ammonium salt, p-aminobenzoic acid ammonium salt, p-toluenesulfonic acid ammonium salt, methanesulfonic acid ammonium salt, trifluoromethanesulfonic acid ammonium salt, trifluoroethanesulfonic acid ammonium salt, etc. The ammonium salt compound of these is mentioned.

  Further, the ammonium moiety of the ammonium salt compound is methylammonium, dimethylammonium, trimethylammonium, tetramethylammonium, ethylammonium, triethylammonium, tetraethylammonium, propylammonium, dipropylammonium, tripropylammonium, tetrapropylammonium, Examples also include ammonium salt compounds substituted with butylammonium, dibutylammonium, tributylammonium, tetrabutylammonium, ethanolammonium, diethanolammonium, triethanolammonium, and the like.

  Examples of onium salts other than the above ammonium salts include phosphonium salts, arsonium salts, stibonium salts, oxonium salts, sulfonium salts, selenonium salts, stannonium salts, iodonium salts, and the like. From the viewpoint of the stability of the composition, ammonium salts can be used. A salt is preferable, and a quaternary ammonium salt is more preferable.

  Examples of the ammonium salt include tetramethylammonium oxide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium fluoride, tetrabutylammonium oxide, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium fluoride, Tetramethylammonium nitrate, tetramethylammonium acetate, tetramethylammonium propionate, tetramethylammonium maleate, tetramethylammonium sulfate, and the like. From the viewpoint of the electrical properties of the silica-based coating, tetramethylammonium nitrate, Tetramethylammonium acetate, tetramethylammonium propionate, tetramethylammonium Umumarein salts, ammonium salts such as tetramethylammonium sulfate is particularly preferred.

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

  The mixing ratio of these onium salts is (a) 0.001 to 0.5% by weight with respect to the total amount of siloxane resin, that is, (a) 0.001 to 0 with respect to 100 parts by weight of the total amount of siloxane resin. 0.5 part by weight, (a) 0.001 to 0.4% by weight based on the total amount of siloxane resin, that is, (a) 0.001 part per 100 parts by weight of siloxane resin. It is more preferable that it is -0.4 weight part, It is 0.001-0.3 weight% with respect to the total amount of (a) siloxane resin, ie, (a) 100 weight part of total amount of siloxane resin. It is particularly preferably 0.001 to 0.3 parts by weight, and (a) 0.001 to 0.2% by weight with respect to the total amount of siloxane resin, that is, (a) 100 parts by weight of the total amount of siloxane resin. In And more preferably 0.001 to 0.2 parts by weight, and (a) 0.001 to 0.1% by weight based on the total amount of siloxane resin, that is, (a) the total amount of siloxane resin is 100. It is very preferable that it is 0.001 to 0.1 parts by weight with respect to parts by weight, and (a) 0.01 to 0.1% by weight with respect to the total amount of siloxane resin, that is, (a) siloxane Most preferably, it is 0.01 to 0.1 parts by weight with respect to 100 parts by weight of the total amount of resin. If the blending ratio is less than 0.001% by weight, the final silica-based film tends to have poor electrical properties, mechanical strength, and the like. Etc. tend to be inferior, and the flatness, electrical characteristics, and process suitability of the silica-based coating tend to be inferior.

  These onium salts can be added to a desired concentration after being dissolved or diluted in water or a solvent as necessary. Further, the timing of addition is not particularly limited, and examples include the time when the component (a) is hydrolyzed, during the hydrolysis, at the end of the reaction, before and after the solvent is distilled off, and when the acid generator is added.

  Moreover, when an onium salt is used as an aqueous solution, the pH is preferably 1.5 to 10, more preferably 2 to 8, and particularly preferably 3 to 6. When the pH is out of the range, the composition tends to be inferior in stability, film formability and the like.

<Other ingredients>
In addition, a dye, a surfactant, a silane coupling agent, a thickener, an inorganic filler, a thermally decomposable compound such as polypropylene glycol, a volatile compound, etc. are further added within a range that does not impair the purpose and effect of the present invention. May be. 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.

  The thermal decomposable compound and the volatile compound are not particularly limited as long as they are thermally decomposable or volatile at a heating temperature of 250 to 500 ° C., for example, a polymer having a polyalkylene oxide structure, ( Examples include meth) acrylate polymers, polyester polymers, polycarbonate polymers, polyanhydride polymers, and tetrakissilanes.

  If the thermal decomposable compound and the volatile compound have thermal decomposability or volatility at a temperature lower than 250 ° C., they will be pyrolyzed and volatilized before the siloxane skeleton is formed, so that desired dielectric properties cannot be obtained. There is a fear. On the other hand, if it is thermally decomposable or volatile at a temperature exceeding 500 ° C., the wiring metal may be deteriorated. Therefore, if it decomposes or volatilizes in such a temperature range, there is an advantage that it is easy to adjust the dielectric characteristics of the insulating film while suppressing the deterioration of the wiring metal.

  Examples of the polyalkylene oxide structure include a polyethylene oxide structure, a polypropylene oxide structure, a polytetramethylene oxide structure, a polybutylene oxide structure, and the like. Specifically, polyoxyethylene alkyl ether, polyoxyethylene sterol ether, polyoxyethylene lanolin derivative, ethylene oxide derivative of alkylphenol formalin condensate, polyoxyethylene polyoxypropylene block copolymer, polyoxyethylene polyoxypropylene alkyl ether, etc. Ether type compounds, polyoxyethylene glycerin fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene fatty acid alkanolamide sulfate and other ether ester type compounds, polyethylene glycol fatty acid ester, ethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid Esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, etc. And the like, such as chromatography ether ester type compounds.

  Examples of acrylic acid esters and methacrylic acid esters constituting the (meth) acrylate polymer include, for example, acrylic acid alkyl esters, methacrylic acid alkyl esters, acrylic acid alkoxyalkyl esters, methacrylic acid alkyl esters, and methacrylic acid alkoxyalkyl esters. Etc.

  Examples of the alkyl acrylate include, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, pentyl acrylate, hexyl acrylate, and the like. -6 alkyl ester, methacrylic acid alkyl ester, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, pentyl methacrylate, hexyl methacrylate, etc. Examples of alkyl esters having 1 to 6 carbon atoms and alkoxyalkyl acrylates include methoxymethyl acrylate, ethoxyethyl acrylate, and alkoxyalkyl methacrylates. Kishimechiru, like methacrylate ethoxyethyl.

  Examples of the acrylic acid and methacrylic acid having a hydroxyl group include 2-hydroxylethyl acrylate, 2-hydroxylpropyl acrylate, 2-hydroxylethyl methacrylate, 2-hydroxylpropyl methacrylate, and the like.

  Examples of the polyester include polycondensates of hydroxycarboxylic acids, ring-opening polymers of lactones, polycondensates of aliphatic polyols and aliphatic polycarboxylic acids, and the like.

  Examples of the polycarbonate include polycondensates of carbonic acid and alkylene glycol such as polyethylene carbonate, polypropylene carbonate, polytrimethylene carbonate, polytetramethylene carbonate, polypentamethylene carbonate, and polyhexamethylene carbonate.

  Examples of the polyanhydride include polycondensates of dicarboxylic acids such as polymalonyl oxide, polyadipoyl oxide, polypimeyl oxide, polysuberoyl oxide, polyazelayl oxide, polysebacoyl oxide, and the like.

  Examples of the tetrakissilanes include tetrakis (trimethylsiloxy) silane, tetrakis (trimethylsilyl) silane, tetrakis (methoxyethoxy) silane, tetrakis (methoxyethoxyethoxy) silane, and tetrakis (methoxypropoxy) silane.

  These may be used alone or in combination of two or more.

  In addition, when using the composition for silica-type film formation of this invention for an electronic component, it is desirable not to contain an alkali metal or an alkaline-earth metal, and even if it is contained, those metal ion density | concentrations in a composition are 100 ppb. Or less, more preferably 20 ppb or less. When these metal ion concentrations exceed 100 ppb, 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. In addition to the above, organic polymers such as polyethylene terephthalate, polyethylene naphthalate, polyamide, polycarbonate, polyacryl, nylon, polyether sulfone, polyvinyl chloride, polypropylene, and triacetyl cellulose can be used as these substrates. . Also, a plastic film such as the organic polymer 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 500 to 5000 rotations / minute, more preferably 500 to 3000 rotations / minute, to form a film. If the rotational speed is less than 500 revolutions / minute, the film uniformity tends to deteriorate, and if it exceeds 5000 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. The film thickness when used for liquid crystal is preferably 0.1 to 20 μm, the film thickness when used for a photoresist is preferably 0.1 to 2 μm, and the film when used for an optical waveguide The 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 for a film thickness of 0.5 to 2.0 μm, and can be preferably used for a film thickness of 0.5 to 1.5 μm. It can be particularly preferably used for a film thickness of 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 may be adjusted. When using the spin coating method, 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 the film thickness is increased, the concentration of the component (a) is increased, and when the film thickness is decreased, the component (a) It can be controlled by lowering the concentration of. In addition, when adjusting the film thickness using the spin coating method, for example, when increasing the film thickness, the rotation speed is decreased or the number of coatings is increased, and when the film thickness is decreased, the rotation speed is decreased. It can be adjusted by raising or reducing the number of times of application.

  Next, preferably in the coating film on a hot plate or the like at 50 to 350 ° C., more preferably 100 to 350 ° C., further preferably 100 to 300 ° C., particularly preferably 150 to 300 ° C., very preferably 200 to 250 ° C. Dry the organic solvent. If this drying temperature is less than 50 ° C., the organic solvent tends to be not sufficiently dried. Further, when the drying temperature exceeds 350 ° C., for example, when the composition for forming a silica-based film contains a pyrolytic volatile compound, the pyrolytic volatile compound is likely to volatilize before the formation of the siloxane skeleton. There is a tendency for defects such as a decrease in the dielectric properties of the coating to occur. The drying time at this time is preferably 1 second to 1 hour, more preferably 2 seconds to 10 minutes, further preferably 10 seconds to 5 minutes, and particularly preferably 30 seconds to 3 minutes. When the drying time exceeds 1 hour, the throughput tends to decrease, and when the drying time is less than 1 second, it tends to be insufficiently dried.

  Next, the coating film from which the organic solvent has been removed is baked at a heating temperature of preferably 250 to 500 ° C., more preferably 350 to 500 ° C., and final curing is performed. In this manner, a silica-based film (Low-k film) that can exhibit a low dielectric constant even in a high-frequency region of 100 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).

  More specifically, it is obtained as follows. First, a film is formed so that the film thickness is 0.5 to 0.6 μm. Specifically, after coating by spin coating on a low resistivity silicon wafer (resistivity <10 Ωcm), the solvent was removed with a hot plate heated to 200 ° C., and finally cured at 400 ° C./30 minutes in a nitrogen atmosphere. By doing so, a film is formed. After the coating is formed, Al metal is vacuum-deposited with a vacuum deposition apparatus so that the diameter is 2 mm and the thickness is about 0.1 μm. A structure in which an insulating film is sandwiched between an Al metal and a low resistivity silicon wafer is formed, and the charge capacity is measured. Here, the film thickness is a film thickness measured by an ellipsometer L116B manufactured by Gartner, and specifically, a film thickness obtained from a phase difference generated by irradiation with He-Ne laser irradiation on the coating film is used. .

The relative dielectric constant of the coating is measured by measuring the charge capacity between the Al metal and the low resistivity silicon wafer. The charge capacity is measured by connecting a dielectric test fixture (Yokogawa Electric: HP16451B) to an LF impedance analyzer (Yokogawa Electric: HP4192A). A value measured with a frequency at the time of measurement of 1 MHz is used. The measured value is substituted into the following formula (2), and the relative dielectric constant of the film is measured.
(Relative dielectric constant of film) = 3.597 × 10 ⁻² × (charge capacity [unit pF]) × (film thickness [unit μm]) (2)

  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.

  In addition, the heating time during the curing is preferably 2 to 60 minutes, and more preferably 2 to 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 rapid thermal annealing (RTA).

  The relative dielectric constant after the final heating step of the silica-based coating of the present invention is preferably 2.6 or less, and more preferably 2.2 or less. The lower limit is usually about 1.5. If it is less than 1.5, the mechanical strength may be lowered, which is not preferable. In order to reduce the relative dielectric constant, for example, it is effective to increase the amount of micropores introduced. However, if the introduction amount of micropores is too large, the mechanical strength of the silica-based film may be reduced.

  The silica-based coating of the present invention preferably has an elastic modulus of 2.5 GPa or more, more preferably 3.0 GPa or more, particularly preferably 3.5 GPa or more, and 4.0 GPa or more. It is very preferable that it is 4.5 GPa or more. The upper limit is not particularly limited, but is usually about 30 GPa. If the elastic modulus is less than 2.5 GPa, for example, a problem may occur during processing when used as a semiconductor insulating film. The increase in elastic modulus can be achieved, for example, by reducing the proportion of pores contained in the silica-based coating.

  In the present invention, the elastic modulus of the film is an elastic modulus in the vicinity of the surface of the film, and a value obtained using a nanoindenter DCM manufactured by MTS is used. As a method for forming the coating, a coating that is spin-coated on a silicon wafer so that the coating thickness is 0.5 to 0.6 μm, the solvent is removed with a hot plate, and then cured at 425 ° C./30 minutes is used. . A thin film is not preferable because it is affected by the substrate. The vicinity of the surface indicates the elastic modulus at a depth within 1/10 of the film thickness, specifically, the depth of 15 to 50 nm from the film surface.

Further, the load and the load speed are varied in a relationship represented by the following formula (3).
dL / dt × 1 / L = 0.05 [unit sec ⁻¹ ] (3)
Here, L indicates a load and t indicates time. In addition, a Barkovic indenter (material: diamond) is used as the indenter for pushing, and the amplitude frequency of the indenter is set to 45 Hz for measurement.

  Moreover, since the coating film of the present invention is silica-based, it is excellent in heat resistance and moisture resistance as compared with a coating film made of a conventional organic polymer.

  The flatness of the film of the present invention is such that when the film thickness after the final heating process is 45% to 100% with respect to the depth of the concave portion of the substrate, the concave portion of the concave portion becomes 35% or less. Preferably, it is more preferably 30% or less.

The flatness ratio is calculated by observing the cross section of the recess with S570, which is an SEM manufactured by Hitachi, Ltd. (see FIG. 1). More specifically, when the depth of the rectangular rectangular recess 1 having a width of 750 nm and a depth of 700 nm is A and the depth to the deepest portion of the film 2 filled in the recess 1 is B, the following formula (4 ) Is a flat rate.
(Flat rate [unit%]) = ((A−B) / A) × 100 (4)

  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. Semiconductor devices include individual semiconductors such as diodes, transistors, compound semiconductors, thermistors, varistors, thyristors, DRAMs (Dynamic Random Access Memory), SRAMs (Static Random Access Memory), EPROMs (Erasable Programmable Read) -Only memory), Mask ROM (Mask Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), memory elements such as flash memory, theoretical circuits such as microprocessor, DSP, ASIC, etc. Element, integrated circuit element such as compound semiconductor represented by MMIC (monolithic microwave integrated circuit), hybrid integrated circuit (hybrid IC), light emitting diode, charge Such as a photoelectric conversion element such as a coupling element and the like. Examples of the multilayer wiring board include a high-density wiring board such as MCM.

  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. By such application, high reliability can be achieved simultaneously with high performance such as reduction of signal propagation delay time.

  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.

  Moreover, although it can be used also as uses, such as an optical waveguide, a use application is not this limitation and can be used conveniently for manufacture of an electronic component.

  Since the silica-based film formed by the composition for forming a silica-based film of the present invention has excellent flatness, the composition for forming a silica-based film is applied to the surface of a substrate having irregularities on the surface, and the flatness is excellent. A silica-based film can be obtained. Examples of the substrate having irregularities on the surface include a substrate in which an electrode or wiring pattern is formed on the substrate and the surface has irregularities, and a substrate in which the substrate is etched into a pattern and the surface has irregularities. .

  There are no particular restrictions on these uneven patterns, but for example, a pattern having a convex part height (or concave part depth) of about 100 to 1000 nm (more preferably 250 to 500 nm) or a concave part width of 10 to 1000 nm (more A pattern of preferably about 20 to 100 nm) is preferable, and a substrate having a plurality of these patterns is preferable.

  Since the flatness is improved by applying the composition for forming a silica-based film of the present invention to these substrates, for example, the amount of the composition for forming a silica-based film can be reduced. In addition, in the multilayer wiring of semiconductor devices, there is a problem that the upper layer wiring is short-circuited if the lower layer wiring is poor in flatness. Can be reduced.

  Further, for example, when a silica-based film forming composition is applied to a substrate 1 having an uneven surface as shown in FIG. 1 and the silica-based film 2 is formed by heating, the silica is also formed on the convex portion of the substrate 1 surface. A system film may be formed, but at that time, it can be removed by performing a polishing treatment or the like as necessary.

  Hereinafter, specific examples according to the present invention will be described, but the present invention is not limited thereto.

[Example 1 (0.05 parts by weight of TMA)]
In a solution prepared by dissolving 77.3 g of tetraethoxysilane and 60.3 g of methyltriethoxysilane in 270.8 g of cyclohexanone, 40.5 g of water in which 0.44 g of 60% nitric acid was dissolved was dropped over 10 minutes with stirring. did. After completion of the dropwise addition, the mixture was reacted for 1.5 hours, and then 0.95 g of a 2.4 wt% tetramethylammonium nitrate aqueous solution was added and reacted for 0.5 hours to obtain a polysiloxane solution. Thereafter, the generated ethanol and low-boiling substances were distilled off in a warm bath under reduced pressure using a rotary evaporator, and 11.8 g of polypropylene glycol was added to prepare 400 g of a silica film-forming composition.

[Example 2 (TMA 0.1 parts by weight)]
In a solution prepared by dissolving 77.3 g of tetraethoxysilane and 60.3 g of methyltriethoxysilane in 269.8 g of cyclohexanone, 40.5 g of water in which 0.44 g of 60% nitric acid was dissolved was dropped over 10 minutes with stirring. did. After completion of the dropwise addition, the mixture was reacted for 1.5 hours, and then 1.9 g of a 2.4 wt% tetramethylammonium nitrate aqueous solution was added and reacted for 0.5 hours to obtain a polysiloxane solution. Thereafter, the generated ethanol and low-boiling substances were distilled off in a warm bath under reduced pressure using a rotary evaporator, and 11.8 g of polypropylene glycol was added to prepare 400 g of a silica film-forming composition.

[Example 3 (TMA 0.3 parts by weight)]
In a solution prepared by dissolving 77.3 g of tetraethoxysilane and 60.3 g of methyltriethoxysilane in 266.0 g of cyclohexanone, 40.5 g of water in which 0.44 g of 60% nitric acid was dissolved was dropped over 10 minutes with stirring. did. After completion of the dropwise addition, the mixture was reacted for 1.5 hours, and then 5.7 g of a 2.4 wt% tetramethylammonium nitrate aqueous solution was added and reacted for 0.5 hours to obtain a polysiloxane solution. Thereafter, the generated ethanol and low-boiling substances were distilled off in a warm bath under reduced pressure using a rotary evaporator, and 11.8 g of polypropylene glycol was added to prepare 400 g of a silica film-forming composition.

[Comparative Example 1 (TMA 1.0 part by weight)]
In a solution prepared by dissolving 77.3 g of tetraethoxysilane and 60.3 g of methyltriethoxysilane in 252.7 g of cyclohexanone, 40.5 g of water in which 0.44 g of 60% nitric acid was dissolved was dropped over 10 minutes with stirring. did. After completion of the dropwise addition, the mixture was reacted for 1.5 hours, and then 19 g of a 2.4 wt% tetramethylammonium nitrate aqueous solution was added and reacted for 0.5 hours to obtain a polysiloxane solution. Thereafter, the generated ethanol and low-boiling substances were distilled off in a warm bath under reduced pressure using a rotary evaporator, and 11.8 g of polypropylene glycol was added to prepare 400 g of a silica film-forming composition.

[Comparative Example 2 (TMA 2.0 parts by weight)]
In a solution prepared by dissolving 77.3 g of tetraethoxysilane and 60.3 g of methyltriethoxysilane in 233.8 g of cyclohexanone, 40.5 g of water in which 0.44 g of 60% nitric acid was dissolved was dropped over 10 minutes with stirring. did. After completion of the dropwise addition, the mixture was reacted for 1.5 hours, and then 37.8 g of a 2.4 wt% tetramethylammonium nitrate aqueous solution was added and reacted for 0.5 hours to obtain a polysiloxane solution. Thereafter, the generated ethanol and low-boiling substances were distilled off in a warm bath under reduced pressure using a rotary evaporator, and 11.8 g of polypropylene glycol was added to prepare 400 g of a silica film-forming composition.

[Preparation of coating for flatness evaluation]
The film thickness after the final heating process (final curing) on the patterned wafer having the recesses having a width of 750 nm and a depth of 700 nm was applied to the composition for forming a silica-based film prepared in Examples 1 to 3 and Comparative Examples 1 and 2. Was applied at a rotational speed of 2000 to 3000 rpm for 30 seconds (that is, after a silica-based film forming composition was applied onto a flat Si wafer and finally heated). The silica-based coating was applied under coating conditions such that the film thickness was 45% of 700 nm). After spin coating, it was heated at 250 ° C. for 3 minutes. Thereafter, the coating was finally cured at 425 ° C. for 30 minutes in a quartz tube furnace in which the O ₂ concentration was controlled to around 100 ppm.

[Preparation of coatings for measuring electrical properties (dielectric constant) and film strength (elastic modulus)]
After dropping the composition for forming a silica-based film prepared in Examples 1 to 3 and Comparative Examples 1 and 2 onto a Si wafer, the film thickness of the silica-based film is 0.5 to 0.6 μm. It spin-coated for 30 second at 1000-3000 rpm. After spin coating, it was heated at 250 ° C. for 3 minutes. Thereafter, the coating was finally cured at 425 ° C. for 30 minutes in a quartz tube furnace in which the O ₂ concentration was controlled to around 100 ppm. Here, if the thickness of the silica-based coating is thin, it is not preferable because it is affected by the base.

  The flatness, electrical characteristics, and film strength of the silica coating were evaluated by the following methods for the silica coating formed by the film forming method.

[Evaluation of flatness]
Here, the film thickness of the silica-based film is a film thickness measured with an ellipsometer L116B manufactured by Gartner. Specifically, the film thickness is obtained from a phase difference caused by irradiation with He-Ne laser irradiation on the film. Was used. Then, the value of B in FIG. 1 was obtained, and together with the value of A (corresponding to 700 nm of the recess depth of the pattern wafer in this embodiment), the flatness was obtained by substituting into the above equation (4). In addition, it shows that flatness is so favorable that a flat rate is small.

  The flatness was calculated by observing the cross section of the recess using a scanning electron microscope S570 manufactured by Hitachi, Ltd.

[Specific permittivity measurement]
An aluminum coating is formed on a silica-based coating to a thickness of 2 mm and a thickness of 0.1 μm by a vacuum deposition method. The charge capacity of this sample is measured with a dielectric test using an LF impedance analyzer (Yokogawa Electric Corporation: HP4192A). Using a device connected to a fixture (manufactured by Yokogawa Electric: HP16451B), the measurement was performed under conditions of a temperature of 23 ± 2 ° C., a humidity of 40 ± 10%, and a use frequency of 1 MHz. Then, the measured value of the charge capacity was substituted into the above formula (2), and the relative dielectric constant of the silica-based film was calculated.

(Elastic modulus measurement)
Using nanoindenter SA2 (DCM, manufactured by MTS), temperature: 23 ° C. ± 2 ° C., frequency: 75 Hz, measurement range of elastic modulus: 1/10 or less of interlayer insulating film thickness, does not vary with indentation depth The elastic modulus of the silica-based coating was measured under a range of conditions.

〔Evaluation results〕
The results are shown in Table 1.

  A composition for forming a silica-based film comprising (a) a siloxane resin, (b) a solvent capable of dissolving the component (a), and (c) an onium salt according to the present invention, and a mixing ratio of the component (c). Examples 1 to 3 using the composition for forming a silica-based film in which the amount is 0.001 to 0.5% by weight based on the total amount of the component (a) are excellent in flatness. Moreover, it has sufficient low dielectric property and mechanical strength.

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

It is a schematic cross section for demonstrating a flat rate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... Silica-type film | membrane embedded in the board | substrate recessed part.

Claims (13)

  (A) a siloxane resin, (b) a solvent capable of dissolving the component (a), and (c) a composition for forming a silica-based coating film containing an onium salt, the blending of the component (c) A composition for forming a silica-based film having a ratio of 0.001 to 0.5 parts by weight with respect to 100 parts by weight of the total amount of the component (a). As the (a) siloxane resin, the following general formula (1):
R ¹ _n SiX _4-n (1)
(In the formula, R ¹ represents an H atom or F atom, or a group containing B atom, N atom, Al atom, P atom, Si atom, Ge atom or Ti atom, or an organic group 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, each X is the same But it may be different.)
The composition for silica-type film formation of Claim 1 containing resin obtained by hydrolytic condensation of the compound represented by these.   As the (a) siloxane resin, an H atom, an F atom, a B atom, an N atom, an Al atom, a P atom, an Si atom bonded per one atom of the Si atom forming the siloxane bond of the siloxane resin, The composition for forming a silica-based film according to claim 1 or 2, comprising a resin in which the total number of at least one atom selected from the group consisting of Ge atom, Ti atom and C atom is 0.65 or less.   The silica system according to any one of claims 1 to 3, wherein a blending ratio of the (c) onium salt is 0.001 to 0.4 parts by weight with respect to 100 parts by weight of the total amount of the component (a). Film-forming composition.   The silica system according to any one of claims 1 to 3, wherein a blending ratio of the (c) onium salt is 0.001 to 0.3 parts by weight with respect to 100 parts by weight of the total amount of the component (a). Film-forming composition.   The silica system according to any one of claims 1 to 3, wherein a blending ratio of the (c) onium salt is 0.001 to 0.2 parts by weight with respect to 100 parts by weight of the total amount of the component (a). Film-forming composition.   The silica system according to any one of claims 1 to 3, wherein a blending ratio of the (c) onium salt is 0.001 to 0.1 parts by weight with respect to 100 parts by weight of the total amount of the component (a). Film-forming composition.   The silica system according to any one of claims 1 to 3, wherein a blending ratio of the (c) onium salt is 0.01 to 0.1 parts by weight with respect to 100 parts by weight of the total amount of the component (a). Film-forming composition.   The composition for forming a silica-based film according to any one of claims 1 to 8, which is applied onto a substrate having irregularities on the surface.   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 9 is applied on a substrate to form a coating film, and the coating is performed. A method for forming a silica-based film, in which an organic solvent contained in a film is removed and then the coating film is baked.   The formation method of the silica type coating film of Claim 10 with which the surface of the said board | substrate which apply | coats the said composition for silica-type film formation has an unevenness | corrugation.   A silica-based coating provided on a substrate and formed by the method for forming a silica-based coating according to claim 10 or 11.   An electronic component comprising the substrate and the silica-based film according to claim 12 formed thereon.

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