JP2001048977A - Purification of polyalkylene oxide derivative, film- forming composition, method for forming film and low- density film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To purify a polyalkylene oxide derivative capable of forming interlayer insulating film containing a decreased amount of metal impurities, excellent in balance between dielectric constant, mechanical strength, etc., and having a low leakage current by contacting the polyalkylene oxide derivative with an acid. SOLUTION: By contacting (A) a polyalkylene oxide derivative with (B) an acid (preferably an organic acid such as citric acid, oxalic acid and malonic acid), the polyalkylene oxide derivative is purified. The purified component A is formulated with (C) a matrix component (preferably polysiloxane or an aromatic organic polymer) and is mixed with a catalyst, an organic solvent, etc., to form a film-forming composition. The quantity consumed of the component A preferably is 1 to 80 wt.% based on the weight of the component C. By applying the resultant composition to a substrate plate and heating them, a coating film suitable for an insulating film, especially an interlayer insulating film for an integrated circuit can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for purifying metal-containing components of a decomposable component and a composition for forming a film, and more particularly to a dielectric material having a reduced metal content of impurities. The present invention relates to a film-forming composition excellent in properties, mechanical strength, and the like, and a film obtained by curing the composition.

[0002]

Conventionally, as an interlayer insulating film in semiconductor devices and the like, silica is formed Te than by a vacuum process such as CVD (SiO ₂₎ film is often used. And in recent years,
In order to form a more uniform interlayer insulating film, S
A coating-type insulating film called a OG (Spin on Glass) film, which is mainly composed of a hydrolysis product of tetraalkoxylan, has also been used. Also, with the high integration of semiconductor elements and the like, an interlayer insulating film having a low dielectric constant, which is mainly composed of organopolysiloxane and is called organic SOG, has been developed. However, with higher integration of semiconductor devices and the like, better electrical insulation between conductors is required, and therefore, an interlayer insulating film material having a lower dielectric constant has been required.

[0003] Japanese Patent Application Laid-Open No. 6-181201 discloses a coating composition for forming an insulating film having a lower dielectric constant as an interlayer insulating film material. Such a coating composition has a low water absorption and is intended to provide an insulating film of a semiconductor device having excellent crack resistance, and the constitution is
Titanium, zirconium, niobium and tantalum; an organometallic compound containing at least one element selected from the group consisting of polycondensation of an organosilicon compound having at least one alkoxy group in the molecule; It is a coating type composition for forming an insulating film mainly comprising an oligomer. However, the dielectric constant of the conventional inorganic interlayer insulating film material is 3.0 or more, which is insufficient for high integration. Therefore, a method of adding an easily decomposable substance to an inorganic material and decomposing only the easily decomposable substance by heating to make the inorganic material porous has been studied.

[0004]

However, when a conventionally known composition for forming a porous film is used for a semiconductor, there is a problem that a leak current is high.

The present invention improves the dielectric constant characteristics by reducing the metal content of impurities, and is excellent in balance of mechanical strength and the like.
It is another object of the present invention to provide a method for purifying a polyalkylene oxide derivative which forms an interlayer insulating film having a low leakage current, and a film-forming composition using the purified polyalkylene oxide derivative. Hereinafter, the present invention will be described in detail.

Polyalkylene oxide derivative The structure of the polyalkylene oxide derivative of the present invention includes a polyethylene oxide structure, a polypropylene oxide structure, a polytetramethylene oxide structure, a polybutylene oxide structure and the like. Specifically, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene sterol ether, polyoxyethylene lanolin derivative, ethylene oxide derivative of alkylphenol formalin condensate, polyoxyethylene polyoxypropylene block copolymer, polyoxyethylene polyoxypropylene block copolymer Ethylene polyoxypropylene random copolymer, ether type compounds such as polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene glycerin fatty acid ester,
Ether ester type compounds such as polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene fatty acid alkanolamide sulfate, polyethylene glycol fatty acid ester, ethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid ester, sorbitan fatty acid ester And ether ester type compounds such as propylene glycol fatty acid ester and sucrose fatty acid ester.

Among them, polyoxyalkylene block copolymers such as polyoxyethylene polyoxypropylene block copolymers, ethylene glycol fatty acid esters, polyoxyethylene alkylphenyl ethers, and polyoxyethylene alkyl ethers are preferred.
Examples of the polyoxyethylene polyoxypropylene block copolymer include compounds having the following block structures. - a (A) n- (B) m- (A) l- ( In the formula, A group represented by -CH ₂ CH ₂ O-, the B - (A) n- (B ) m- -
A group represented by CH ₂ CH (CH ₃ ) O—, wherein n is 1
~ 90, m is a number from 10 to 99, l is a number from 0 to 90)
As ethylene glycol fatty acid esters, R-CO-
And a compound represented by (CH2CH2O) nH. As polyoxyethylene alkyl phenyl ether,
And a compound represented by R-C6H4-O- (CH2CH2O) nH. The polyoxyethylene alkyl ether is represented by R
And a compound represented by O- (CH2CH2O) nH.

The polyalkylene oxide derivative is purified by dissolving the polyalkylene oxide derivative in an organic solvent which is immiscible with water and dissolves the polyalkylene oxide derivative, repeatedly washed with an organic acid aqueous solution, and finally deionized. Wash with purified water. For example, benzene, toluene, xylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, i-propylbenzene, diethylbenzene, i-butylbenzene, triethylbenzene, di-i-propylbenzene, n-amylnaphthalene, trimethylbenzene Aromatic hydrocarbon solvents such as ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, n-pentyl acetate, and acetic acid s
ec-pentyl, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, n-nonyl acetate, ethyl acetoacetate,
Ethyl propionate, n-butyl propionate, i-amyl propionate, diethyl oxalate, di-n-oxalate
-Butyl, methyl lactate, ethyl lactate, n-butyl lactate,
Ester solvents such as n-amyl lactate, diethyl malonate, dimethyl phthalate and diethyl phthalate; methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-
Butyl ketone, diethyl ketone, methyl-i-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-i-butyl ketone, trimethylnonanone, cyclohexanone, methylcyclohexanone, 2,4- Ketone solvents such as pentanedione, acetophenone and fenchone; ether solvents such as i-propyl ether, n-butyl ether, n-hexyl ether, 2-ethylhexyl ether, ethylene glycol mono-2-ethylbutyl ether; sec-butanol; t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, se
c-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, s
ec-heptanol, heptanol-3, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, 2,6-dimethylheptanol-4, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, cyclohexanol, methylcyclohexanol, 3,
Examples thereof include alcohol solvents such as 3,5-trimethylcyclohexanol, benzyl alcohol, and phenylmethylcarbinol. Among them, ethyl acetate, toluene, and cyclohexanone are preferred from the viewpoint of purification efficiency after washing with an aqueous acid solution and separation efficiency of an organic phase and an aqueous phase. These organic solvents are 1 to 50% by weight, preferably 3 to 30% by weight based on the polyalkylene oxide derivative.
Can be used in the range.

Examples of the organic acid include formic acid, acetic acid, citric acid, oxalic acid, malonic acid, lactic acid, tartaric acid, and the like, and citric acid, oxalic acid, malonic acid and the like are particularly preferred from the viewpoint of purification efficiency. The organic acid aqueous solution generally has an organic acid concentration of 0.1 to 30% by weight, preferably 0.5 to 20% by weight. The water used in the present invention is deionized purified water. The range of use of the organic solvent solution of the polyalkylene oxide derivative and the aqueous solution of the organic acid is usually 5/95 to 95/5, preferably 20/80 to 80/20 in weight ratio (polyalkylene oxide derivative solution / organic acid aqueous solution). It is. The metal content in the polyalkylene oxide derivative purified by the above method is usually sodium 3
0 ppb or less and iron 10 ppb or less.

Composition for film formation The polyalkylene oxide derivative purified by the purification method of the present invention is combined with a matrix component to form a catalyst,
The composition for film formation can be obtained by mixing with an organic solvent or the like. Examples of the matrix component include polysiloxane and aromatic organic polymers. The polysiloxane comprises a hydrolyzate of a hydrolyzable silane compound and / or a condensate thereof. Examples of the hydrolyzable silane compound include a compound represented by the following general formula (1) and a compound represented by the following general formula (2). Formula (1) R ¹ _a Si (OR ² ) _4-a (1) (R ¹ represents a hydrogen atom, a fluorine atom or a monovalent organic group, R ² represents a monovalent organic group, and a represents 0-2 represents an integer) in formula _{^{(2) R 3 b (R}} 4 O) 3-b Si- (R 7) d -Si (OR 5) 3-c R 6 c (2) (R 3, R ⁴ , R ⁵ and R ⁶ may be the same or different and each represents a monovalent organic group, b and c may be the same or different and represent a number of 0 to 2, and R ⁷ Represents an oxygen atom or — (CH ₂ ) _n —, and d represents 0 or 1.
And n represents a number of 1 to 6. As specific examples of the compound represented by the general formula (1), compounds having n = 0 in the general formula (1) include tetramethoxysilane, tetraethoxysilane, and tetra-n-
Examples thereof include propoxysilane, tetra-iso-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, and tetraphenoxysilane. Specific examples of the compound where n = 1 in the above general formula (1) include:
Methyltrimethoxysilane, methyltriethoxysilane, methyltri-n-propoxysilane, methyltri-
iso-propoxysilane, methyltri-n-butoxysilane, methyltri-sec-butoxysilane, methyltri-tert-butoxysilane, methyltriphenoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltri-n-propoxysilane, ethyltri- iso-propoxysilane, ethyltri-n-
Butoxysilane, ethyltri-sec-butoxysilane, ethyltri-tert-butoxysilane, ethyltriphenoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltri-n-propoxysilane, n-propyltri -Iso
-Propoxysilane, n-propyltri-n-butoxysilane, n-propyltri-sec-butoxysilane,
n-propyltri-tert-butoxysilane, n-propyltriphenoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, i-propyltri-n-propoxysilane, i-propyltri-
iso-propoxysilane, i-propyltri-n-butoxysilane, i-propyltri-sec-butoxysilane, i-propyltri-tert-butoxysilane,
i-propyltriphenoxysilane, n-butyltrimethoxysilane, n-butyltriethoxysilane, n-butyltri-n-propoxysilane, n-butyltri-i
so-propoxysilane, n-butyltri-n-butoxysilane, n-butyltri-sec-butoxysilane,
n-butyltri-tert-butoxysilane, n-butyltriphenoxysilane, sec-butyltrimethoxysilane, sec-butyl-i-triethoxysilane, s
ec-butyl-tri-n-propoxysilane, sec-
Butyl-tri-iso-propoxysilane, sec-butyl-tri-n-butoxysilane, sec-butyl-tri-sec-butoxysilane, sec-butyl-tri-
tert-butoxysilane, sec-butyl-triphenoxysilane, t-butyltrimethoxysilane, t-butyltriethoxysilane, t-butyltri-n-propoxysilane, t-butyltri-iso-propoxysilane, t-butyltri-n-butoxysilane , T-butyl tri-sec-butoxysilane, t-butyl tri-te
rt-butoxysilane, t-butyltriphenoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltri-n-propoxysilane, phenyltri-iso-propoxysilane, phenyltri-
Examples thereof include n-butoxysilane, phenyltri-sec-butoxysilane, phenyltri-tert-butoxysilane, and phenyltriphenoxysilane. Specific examples of the compound where n = 2 in the general formula (1) include dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyl-di-n-propoxysilane, dimethyl-di-iso-propoxysilane, dimethyl-di-n -Butoxysilane, dimethyl-di-sec-butoxysilane, dimethyl-di-tert-butoxysilane,
Dimethyldiphenoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyl-di-n-propoxysilane, diethyl-di-iso-propoxysilane, diethyl-di-n-butoxysilane, diethyl-
Di-sec-butoxysilane, diethyl-di-tert
-Butoxysilane, diethyldiphenoxysilane, di-
n-propyldimethoxysilane, di-n-propyldiethoxysilane, di-n-propyl-di-n-propoxysilane, di-n-propyl-di-iso-propoxysilane, di-n-propyl-di-n -Butoxysilane, di-n-propyl-di-sec-butoxysilane, di-n
-Propyl-di-tert-butoxysilane, di-n-
Propyl-di-phenoxysilane, di-iso-propyldimethoxysilane, di-iso-propyldiethoxysilane, di-iso-propyl-di-n-propoxysilane, di-iso-propyl-di-iso-propoxysilane, Di-iso-propyl-di-n-butoxysilane, di-iso-propyl-di-sec-butoxysilane, di-iso-propyl-di-tert-butoxysilane, di-iso-propyl-di-phenoxysilane,
Di-n-butyldimethoxysilane, di-n-butyldiethoxysilane, di-n-butyl-di-n-propoxysilane, di-n-butyl-di-iso-propoxysilane, di-n-butyl-di -N-butoxysilane, di-n
-Butyl-di-sec-butoxysilane, di-n-butyl-di-tert-butoxysilane, di-n-butyl-
Di-phenoxysilane, di-sec-butyldimethoxysilane, di-sec-butyldiethoxysilane, di-s
ec-butyl-di-n-propoxysilane, di-sec
-Butyl-di-iso-propoxysilane, di-sec
-Butyl-di-n-butoxysilane, di-sec-butyl-di-sec-butoxysilane, di-sec-butyl-di-tert-butoxysilane, di-sec-butyl-di-phenoxysilane, di-tert -Butyldimethoxysilane, di-tert-butyldiethoxysilane,
Di-tert-butyl-di-n-propoxysilane, di-tert-butyl-di-iso-propoxysilane,
Di-tert-butyl-di-n-butoxysilane, di-
tert-butyl-di-sec-butoxysilane, di-
tert-butyl-di-tert-butoxysilane, di-tert-butyl-di-phenoxysilane, diphenyldimethoxysilane, diphenyl-di-ethoxysilane, diphenyl-di-n-propoxysilane, diphenyl-di-iso-propoxysilane , Diphenyl-di-
n-butoxysilane, diphenyl-di-sec-butoxysilane, diphenyl-di-tert-butoxysilane, diphenyldiphenoxysilane, divinyltrimethoxysilane, γ-aminopropyltrimethoxysilane,
γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-trifluoropropyltrimethoxysilane, γ-trifluoropropyltriethoxysilane, etc. it can. These may be used alone or in combination of two or more. Among the compounds represented by the general formula (1), tetraalkoxysilanes such as tetramethoxysilane and tetraethoxysilane, alkyltrialkoxysilanes such as methyltrimethoxysilane and methyltriethoxysilane, dimethyldiethoxysilane, dimethyl Dialkyldialkoxysilanes such as dimethoxysilane are preferred. Further, as the hexafunctional alkoxy compound represented by the general formula (2),
Hexamethoxysilyl-1,2-ethane, hexamethoxysilyl-1,3-propane, hexamethoxysilyl-1,4-butane, hexamethoxysilyl-1,5-pentane, hexamethoxysilyl-1,6-hexane, Hexamethoxysilyl-1,4-
Benzene and the like can be mentioned.

In the film-forming composition of the present invention, the compounds represented by the above general formula (1) are preferably used in combination of two or more, especially tetraalkoxysilane,
It is particularly preferred to include an alkyl trialkoxysilane. Further, when the compound represented by the general formula (1) and the compound represented by the general formula (2) are hydrolyzed and partially condensed, 0.3 to 5.0 mol of water per mol of the alkoxy group is used. Is preferably used, and it is particularly preferable to add 0.5 to 2.0 mol of water. In some cases, the condensate of the compounds represented by the general formulas (1) and (2) preferably has a weight average molecular weight in terms of polystyrene of 500 to 100,000. Examples of the aromatic organic polymer include polyarylene, polyarylene ether, polyimide, polyetherketone, polyquinoline, and polyquinoxaline.

Examples of the acid catalyst that can be used in the present invention include inorganic acids and organic acids. Examples of organic acids include acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oxalic acid, maleic acid, methylmalonic acid, adipic acid, sebacic acid, and gallic acid , Butyric, melitic, arachidonic, mykimic, 2-ethylhexanoic, oleic, stearic, linoleic,
Linoleic acid, salicylic acid, benzoic acid, p-aminobenzoic acid, p-toluenesulfonic acid, benzenesulfonic acid,
Monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid, formic acid, malonic acid, benzenesulfonic acid,
Examples include phthalic acid, fumaric acid, citric acid, tartaric acid and the like. As inorganic acids, for example, hydrochloric acid, nitric acid, sulfuric acid,
Hydrofluoric acid, phosphoric acid and the like can be mentioned. Among these acid catalysts, it is particularly preferable to use an organic acid in the present invention, and among these organic acids, acetic acid, oxalic acid, maleic acid, malonic acid and the like are particularly preferable. The amount of the acid catalyst to be used is generally 0.0001 to 1 mol, preferably 0.001 mol, per 1 mol of the total amount of the alkoxysilane in the hydrolyzable silane compound.
1 to 0.1 mol.

The amount of the polyalkylene oxide derivative used is usually from 1 to 80% by weight, preferably from 5 to 65% by weight, based on the matrix component.

In the present invention, the film-forming composition is used by dissolving each of the above components in an organic solvent. Examples of the organic solvent used in the present invention include aliphatic hydrocarbon solvents such as hexane, heptane, octane, octane, nonane, and decane; aliphatic hydrocarbon solvents such as cyclohexane, methylcyclohexane, and decalin; benzene, toluene ,
Aromatic hydrocarbon solvents such as xylene, ethylbenzene, trimethylbenzene, methylethylbenzene, propylbenzene, diethylbenzene, butylbenzene, triethylbenzene, dipropylbenzene, tetralin, and methylnaphthalene; methanol, ethanol, propanol, butanol, pentanol, -Methoxybutanol, hexanol, heptanol, octanol, nonyl alcohol, decanol, undecyl alcohol, tetradecyl alcohol, heptadecyl alcohol, cyclohexanol, methylcyclohexanol, 3,3
Alcohol solvents such as 5-trimethylcyclohexanol, benzyl alcohol, phenylmethylcarbinol, and diacetone alcohol; phenol solvents such as phenol and cresol; ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, and pentane Diol-2,4,2-methylpentanediol-2,4, hexanediol-2,5, heptanediol-2,4,2-ethylhexanediol-1,3, diethylene glycol, dipropylene glycol, triethylene glycol, Polyhydric alcohol solvents such as tripropylene glycol and glycerin; acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-
Butyl ketone, diethyl ketone, methyl-i-butyl ketone, methyl-amyl ketone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-i-butyl ketone, trimethylnonanone, cyclohexanone, methylcyclohexanone, 2,4-pentanedione, Ketone solvents such as acetonylacetone, diacetone alcohol, acetophenone, and fenchone; i-propyl ether;
n-butyl ether, n-hexyl ether, 2-ethylhexyl ether, dioxolan, 4-methyldioxolan, dioxane, dimethyldioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol Monopentyl ether, ethylene glycol mono-hexyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, ethylene glycol dipentyl ether, ethylene glycol dihexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono -2- Chill ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol mono -n- butyl ether, diethylene glycol di -n- butyl ether, diethylene glycol mono -n- hexyl ether, ethoxy triglycol, tetraethylene glycol di -n
-Butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, propylene glycol dibutyl ether, propylene glycol monomethyl ether acetate Propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, Rahidorofuran, ether solvents such as 2-methyltetrahydrofuran; diethyl carbonate, methyl acetate, ethyl acetate, .gamma.-butyrolactone, gamma
-Valerolactone, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, acetic acid 2-ethylbutyl, 2-ethylhexyl acetate, benzyl acetate,
Cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, ethyl acetoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl acetate, diethylene glycol mono-acetate
n-butyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, glycol diacetate, acetic acid Methoxy triglycol, ethyl propionate, n-butyl propionate, i-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, malonic acid Ester solvents such as diethyl, dimethyl phthalate and diethyl phthalate; N-methylformamide;
N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide,
Nitrogen-containing solvents such as N, N-dimethylacetamide, N-methylpropionamide, N-methylpyrrolidone; dimethyl sulfide, diethyl sulfide, thiophene, tetrahydrothiophene, dimethyl sulfoxide, sulfolane, 1,3
-Sulfur-containing solvents such as propane sultone. These can be used alone or in combination of two or more. In the present invention, it is preferable to use an organic solvent having a boiling point of less than 250 ° C. as the organic solvent,
Specifically, alcohols such as methanol, ethanol and isopropanol, polyhydric alcohols such as ethylene glycol and glycerin, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, propylene glycol monopropyl ether, dipropylene Glycol ether solvents such as glycol monoethyl ether, glycol acetate ether solvents such as ethylene glycol monomethyl acetate, diethylene glycol monobutyl ether acetate, ethylene glycol diacetate, propylene glycol methyl ether acetate, N, N-dimethylacetamide, N, N-dimethylformamide , N-
Amide solvents such as methyl-2-pyrrolidone, acetone,
One or a combination of two or more of ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, acetylacetone and methyl amyl ketone, and carboxylic acid ester solvents such as ethyl lactate, methoxymethyl propionate and ethoxyethyl propionate. Can be mentioned. In the present invention, the amount of the organic solvent used is in the range of 0.3 to 25 times (weight) the total amount of the matrix component, the polyalkylene oxide derivative and the catalyst.

Further, a surfactant may be added to the composition of the present invention in order to improve coatability and smoothness of the coated surface. The surfactant may be an ordinary one containing a CHON-based constituent element, or may contain a Si or F atom. The addition amount is in the range of 1 ppm to 1000 ppm based on the composition solution.

In order to form a film using the composition of the present invention, first, the composition of the present invention is applied to a substrate to form a coating film. Here, examples of the substrate on which the composition of the present invention can be applied include semiconductors, glass, ceramics, and metals, and examples of the application method include spin coating, dipping, and roller blades. The thickness of the coating film to be formed is usually 0.2 to 20 μm in the case of an interlayer insulating film. Next, the formed coating film is heated, and the heating temperature at this time is lower than the decomposition temperature of the component (C). In the present invention, it is necessary to select the heating conditions of the coating film so that the cured film of the component (A) has pores. As the heating method, the formed coating film is heated at a temperature lower than the decomposition temperature of the component (C) to partially cure the component (A), and then heated from a temperature higher than the decomposition temperature of the component (C) to the final temperature. A method of heating to a curing temperature to obtain a porous cured product, and the like. In addition, in order to control the curing rate of the component (A) and the decomposition rate of the component (C), if necessary, heat in a stepwise manner or select an atmosphere such as nitrogen, air, oxygen, or reduced pressure. Can be. Usually, the decomposition temperature of the component (C) is 2
Since the temperature is 50 to 450 ° C., the coating film includes a step of being finally heated to this temperature or higher. This step is preferably performed under reduced pressure or under an inert gas. By the method of the present invention, a film of the present invention having pores of usually 100 nm or less, a porosity of 1 to 70%, and a dielectric constant of
Usually, it is 2.6 to 1.2. The film of the present invention is suitable as an insulating film, and is particularly suitable as an interlayer insulating film for highly integrated circuits.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples. However, the following description generally shows an example of the embodiment of the present invention, and the present invention is not limited by the description without any particular reason. Parts and% in Examples and Comparative Examples indicate parts by weight and% by weight, respectively, unless otherwise specified.

Example 1 Polyethylene glycol, polypropylene glycol,
Block copolymer composed of polyethylene glycol (Newpole PE61 manufactured by Sanyo Chemicals Co., Ltd .: sodium content of 0.1%).
50 g (7 ppm, iron content 0.5 ppm) was dissolved in 200 g of ethyl acetate to prepare a 20 wt% solution. 200 ml of a 1% oxalic acid aqueous solution was added to the solution, and extraction washing was repeated 5 times. The contained sodium and iron were removed from the aqueous layer and finally washed with pure water. After washing, the ethyl acetate was removed, and the amounts of sodium and iron contained in the polyethylene glycol / polypropylene glycol copolymer were measured by an atomic absorption method.
Sodium was reduced to 5 ppb and iron to 3 ppb.

Example 2 Nonylphenol polyethylene addition polymer (sodium content: 1.1 ppm, iron content: 0.9 ppm) 50
g was dissolved in 200 g of toluene to prepare a 20 wt% solution. 200 ml of a 1% oxalic acid aqueous solution was added to the solution, and extraction washing was repeated 5 times. The contained sodium and iron were removed from the aqueous layer and finally washed with pure water. After washing, the ethyl acetate is removed and polyethylene glycol
When the amounts of sodium and iron contained in the polypropylene glycol copolymer were measured by an atomic absorption method,
Sodium was reduced to 5 ppb and iron to 4 ppb, respectively.

Example 3 A polyethylene addition polymer of dodecanoic acid (containing 1.8 ppm of sodium and 0.9 pp of iron)
m) 50 g was dissolved in 200 g of ethyl acetate, and 20 wt.
% Solution was prepared. To the solution is added 2% 1% oxalic acid aqueous solution.
00 ml was added, and extraction washing was repeated 5 times. The contained sodium and iron were removed from the aqueous layer and finally washed with pure water. After washing, the ethyl acetate was removed, and the amounts of sodium and iron contained in the polyethylene glycol / polypropylene glycol copolymer were measured by an atomic absorption method. As a result, sodium was 5 ppb and iron was 2 ppb, respectively.
b.

Example 4 (A) Demetallized and purified raw material, 140.5 g of tetramethoxysilane, 182.7 g of methyltrimethoxysilane, 56.0 g of dimethyldimethoxysilane as a solvent,
Propylene glycol monopropyl ether 394.0
g of a mixed solution of 10.0 g of maleic acid in pure water.
An aqueous solution dissolved in 8 g was added dropwise at room temperature over 1 hour.
After the addition of the mixture was completed, the mixture was further reacted at 60 ° C. for 1 hour, and the produced methanol was distilled off under reduced pressure to obtain a polysiloxane sol. (B) To 100 g of the polysiloxane sol obtained in (A), 8.9 g of the polyethylene oxide-polypropylene oxide-polyethylene oxide block copolymer purified in Example 1 was added to prepare a solution composition for coating.
The sodium and iron contents were less than 1 ppb. The prepared composition was applied on an 8-inch silicon wafer by spin coating, heated at 80 ° C. for 5 minutes, then heated at 200 ° C. under nitrogen for 5 minutes, and further heated at 340 ° C. and 36 ° C. under vacuum.
The resultant was heated at 0 ° C. and 380 ° C. for 30 minutes each, and further heated at 425 ° C. for 1 hour to form a transparent film. Further, the obtained film was evaluated as follows. Table 1 shows the results
Shown in (Evaluation of composition for film formation)

1. Dielectric constant An aluminum electrode pattern was formed on the obtained film by a vapor deposition method to prepare a sample for dielectric constant measurement. The sample was taken at a frequency of 100 kHz,
The dielectric constant of the coating film was measured by a CV method using an HP16451B electrode manufactured by Hewlett-Packard Co., Ltd. and an HP4284A precision LCR meter. Table 1 shows the results. Leakage current A composition sample was applied on a silicon wafer by spin coating, and aluminum was deposited on a coated substrate that was treated under predetermined heat treatment conditions, to produce a substrate for leakage current evaluation. The leak current was measured by Keithley's 651
Using 7A, the current value when a voltage of 0.2 MV / cm was applied to the coating film was measured. The leak current of the coating film was evaluated according to the following criteria. ；: Leak current is less than 10 ⁻⁹ A ×: leak current is 10 ⁻⁹ A or more Metal content Measured by the atomic absorption method.

Example 5 (A) Demetalated purified raw material, 91.2 g of tetramethoxysilane, methyltrimethoxysilane 2 as solvent
An aqueous solution in which 10.0 g of maleic acid was dissolved in 119.4 g of water was added dropwise to a mixed solution of 92.3 g and 387.0 g of propylene glycol monopropyl ether at room temperature over 1 hour. After the addition of the mixture was completed, the mixture was further reacted at 60 ° C. for 1 hour, and the produced methanol was distilled off under reduced pressure to obtain a polysiloxane sol. (B) Example 2 was added to 100 g of the silica sol obtained in (A).
7. The obtained polyethylene oxide derivative purified by
9 g was added to prepare a solution composition for coating. The sodium and iron contents of the infusion composition were 1 ppb or less. The obtained solution is applied on an 8-inch wafer by spin coating, and heated on a hot plate at 80 ° C. for 5 minutes and at 200 ° C. for 5 minutes.
After drying for a minute, the mixture was fired at 425 ° C. for 1 hour under vacuum to obtain a transparent coating film. Evaluation was performed in the same manner as in Example 4. Table 1 shows the results.

Comparative Example 2 A solution composition was prepared in the same manner as in Example 5 except that an unpurified polyalkylene oxide derivative was used in place of the purified polyalkylene oxide derivative used in Example 2, and a coating film was prepared. . Table 1 shows the evaluation results.

[Table 1]

[0025]

The film obtained by curing the composition obtained by the method of demetallizing and purifying the low dielectric component of the present invention has excellent electrical properties and is an insulating film, especially an interlayer insulating film for semiconductors. Suitable for membrane applications.

Claims (7)

[Claims] 1. A method for purifying a polyalkylene oxide derivative, comprising contacting the polyalkylene oxide derivative with an acid. 2. The method for purifying a polyalkylene oxide derivative according to claim 1, wherein the acid is an organic acid. 3. A polyalkylene oxide derivative purified by the method of claim 1. 4. A film-forming composition comprising the polyalkylene oxide derivative according to claim 3 and a matrix component. 5. The composition for forming a film according to claim 4, wherein the matrix component is a polysiloxane or an aromatic organic polymer. 6. A method for producing a film, comprising applying the composition according to claim 3 to a substrate and heating the composition. 7. A low-density film obtained by the method according to claim 6.