JP2003342411A - Porous nanocomposite thin film and method of forming the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a porous thin film which has a low relative permittivity and is excellent in mechanical properties, plasma resistance and chemical resistance. <P>SOLUTION: A porous nanocomposite thin film characterized in that it is a porous material having an average pore diameter of 10 nm or less is obtained by forming a thin film from a composition comprising (A) a precursor of silica, (B) a heat resistant organic polymer, (C) a component that can be removed after the thin film having been formed, and a solvent, and thereafter removing the component (C). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a porous nanocomposite thin film and a method for forming the same.

[0002]

2. Description of the Related Art As electronic devices, multilayer wiring boards and the like are further miniaturized and highly integrated, an insulating film having a lower relative dielectric constant is required to be applied to them.
Therefore, a method of making an existing material porous and introducing an air phase having a relative dielectric constant of 1 into the film has been widely studied. Japanese Patent Application Laid-Open No. 2001-2001, in which silica is used as a skeleton material.
No. 2992, JP-A-2001-98224, etc. are known, and US Pat. No. 6,172,128 is known as one using a heat-resistant organic polymer as a skeletal material. With these techniques, it is possible to introduce pores having a size of 20 nm or less into the film, and a film having a relative dielectric constant of 2.1 to 2.5 is obtained.

However, the above existing technology has two major problems. One is a problem that the mechanical strength of the film is extremely lowered by introducing pores, so that peeling occurs during CMP (chemical mechanical polishing) which is a step of smoothing the surface, for example. For this reason, the porosity cannot be increased to a certain extent or more, and it is practically impossible to obtain a film having a relative dielectric constant of 2 or less. Another issue concerns the shape of the holes. There are so many so-called continuous pores in which pores are connected, so in the process of removing the photoresist after etching, active species in plasma and cleaning chemicals, etc. easily penetrate into the membrane and the quality of the membrane deteriorates. Or there was the problem of being contaminated. These two problems are fatal defects in manufacturing electronic devices and multilayer wiring boards.
The improvement was strongly desired.

In order to improve the mechanical strength of the porous film, a method of reinforcing the porous structure by forming a dense film on the porous film after forming the porous film is described in US Pat. No. 617.
Although it is described in Japanese Patent No. 1687, this method has an effect of improving mechanical strength, but since the porosity of the coating film is reduced by that amount and the relative dielectric constant is increased, it is an essential solution to the problem. It's not.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and more specifically, to provide a coating film having a low relative dielectric constant and excellent mechanical properties, plasma resistance and chemical resistance. Is to provide.

[0006]

The present invention provides silica (A).
And a porous nanocomposite thin film containing a heat-resistant organic polymer (B) and having a mean pore size of 10 nm or less.

The present invention also provides a precursor of silica (A),
A thin film is formed from a composition containing a heat-resistant organic polymer (B), a component (C) that can be removed after the thin film is formed, and a solvent,
A method for forming a porous nanocomposite thin film, which comprises removing the component (C) after that.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The porous nanocomposite thin film containing silica (A) and heat resistant organic polymer (B) in the present invention is a porous thin film having an average pore diameter of 10 nm or less. The average pore diameter is preferably 5 nm or less, more preferably 3 nm or less. The average pore diameter in the present invention is the average pore diameter obtained by the X-ray small angle scattering method. The domain size of each of the silica (A) and the heat resistant organic polymer (B) is preferably several tens nm or less.

Since the wiring interval of electronic devices is becoming narrower year by year and will be several tens of nm in the future, it is preferable that the domain size of each component is as described above. On the other hand, if the average pore diameter exceeds 10 nm, active species in the plasma during device manufacturing and the cleaning chemical solution may easily penetrate into the pores, which may damage the film.

The porosity in the present invention means a porosity of 5 to 5.
70% porosity is preferable, and further 10 to
It is particularly preferably 60%.

The silica (A) in the present invention is substantially represented by the following formula (1), and the silica (A) described below is used.
What is formed from the precursor (henceforth a silica precursor) of is preferable.

(X ¹ X ² SiO) _a (X ³ SiO _3/2 ) _b (SiO ₂ ) _c Formula (1) Here, X ¹ , X ² and X ³ are hydrogen, fluorine and carbon number 1
To 8 represent an alkyl group, an aryl group or a vinyl group, and may be the same or different. a, b and c are each independently a number of 0 or more and 1 or less. However, a + b + c = 1.

As X ¹ , X ² and X ³ , hydrogen, a methyl group, or a phenyl group is preferable because of good heat resistance and mechanical properties, and hydrogen or a methyl group is most preferable. When a is large, the relative dielectric constant of the obtained silica is small, but in order to sufficiently maintain heat resistance and mechanical properties, it is preferably 0.5 or less, more preferably 0.3 or less.
Since c has good heat resistance and mechanical properties, it is preferably 0.2 or more, and preferably 0.9 or less in order to keep the relative dielectric constant low. Further, c is 0.
It is preferably 3 or more and 0.9 or less.

The heat-resistant organic polymer (B) in the present invention
Means a polymer having a thermal decomposition temperature of 400 ° C. or higher. The temperature is preferably 425 ° C or higher, more preferably 450 ° C or higher. Here, the thermal decomposition temperature means a 3% weight loss temperature measured by thermogravimetric analysis (TGA) under a temperature rising condition of 10 ° C./min in an inert gas atmosphere.
The relative dielectric constant of the heat resistant organic polymer (B) in the present invention is preferably 4 or less, more preferably 3 or less. In particular, the thermal decomposition temperature is 450 ° C or higher,
And it is most preferable that the relative dielectric constant is 3 or less. As such a heat-resistant organic polymer (B), JP-A-9-20
2823 and JP-A-10-247646, polyarylene ethers, WO 02/08308
Branched thermosetting polymer described in JP-A-2000-
Preferred examples include aromatic ring-containing polymers such as polyphenylene described in 191752 and fluorine-containing polymers. Further, since the relative dielectric constant can be suppressed to a low level, it is more preferable that the repeating unit does not contain a polar group.

The aromatic ring-containing polymer is preferably a polymer having an aromatic ring-containing repeating unit.

The fluorine content of the fluorine-containing polymer is 10% by mass because the effect of reducing the relative dielectric constant is large.
The above is preferable, and more preferably 30% by mass or more. Further, the fluorine content is preferably 70% by mass or less so that the solubility in the solvent can be sufficiently maintained. In particular, it is preferably 30% by mass to 60% by mass.

The heat-resistant organic polymer (B) in the present invention
Most preferably, it is a polymer containing fluorine and having an aromatic ring-containing repeating unit.

Further, the heat-resistant organic polymer (B) in the present invention preferably has a crosslinkable functional group from the viewpoint of heat resistance and solvent resistance. As the crosslinkable functional group,
A functional group capable of self-crosslinking by heat, light, electron beam or the like is preferable. Functional groups that self-crosslink when heated are electronic devices,
It is more preferable because it has excellent applicability in the process of manufacturing electronic components such as a multilayer wiring board. Further, a crosslinkable functional group containing no polar group is preferable because it can suppress the relative dielectric constant of the polymer to a low level. Such a crosslinkable functional group can also be used as a functional group capable of forming a covalent bond with the silica precursor.

Specific examples of the crosslinkable functional group include an ethynyl group, a 1-oxocyclopenta-2,5-dien-3-yl group (hereinafter referred to as a cyclopentadienone group), a cyano group and an alkoxysilyl group. , Diarylhydroxymethyl group, hydroxyfluorenyl group and the like. From the viewpoint of heat resistance and the like, an ethynyl group is preferable.

The content of the crosslinkable functional group is 0.0 with respect to 1 mol of the repeating unit of the heat resistant organic polymer (B).
A ratio of 5 to 6 mol is preferable. If it is 0.05 mol or more, sufficient heat resistance and chemical resistance can be maintained, and if it is 6 mol or less, the relative dielectric constant can be kept low and the toughness can be kept. Particularly, a ratio of 0.1 to 4 mol is more preferable.

The heat-resistant organic polymer (B) in the present invention
As a preferred specific example of, a polyphenylene synthesized by a Diels-Alder type polymerization reaction between a diene group-containing compound and a dienophile group-containing compound, and a compound between a compound containing two or more phenolic hydroxyl groups and a fluorine-containing aromatic ring-containing compound A fluorine-containing polyarylene ether synthesized by a nuclear substitution type dehydrogenative condensation polymerization reaction can be used.

The polyphenylene is preferably a Diels-Alder type polymerization reaction product between a compound having two or more diene groups and a compound having three or more dienophile groups. As the diene group, a cyclopentadienone group is preferable, and as the biscyclopentadienone derivative having two or more diene groups, 1,4-bis (1-oxo-2,4,5-triphenyl-cyclopenta- Two
5-dien-3-yl) benzene, 4,4'-bis (1
-Oxo-2,4,5-triphenyl-cyclopenta-
2,5-Dien-3-yl) biphenyl, 4,4'-bis (1-oxo-2,4,5-triphenyl-cyclopenta-2,5-dien-3-yl) 1,1'-oxy Bisbenzene, 4,4'-bis (1-oxo-2,4,5
-Triphenyl-cyclopenta-2,5-diene-3-
1,1'-thiobisbenzene, 1,4-bis (1)
-Oxo-2,5-di- [4-fluorophenyl] -4
-Phenyl-cyclopenta-2,5-dien-3-yl) benzene, 4,4'-bis (1-oxo-2,4,
5-triphenyl-cyclopenta-2,5-diene-3
-Yl) 1,1 '-(1,2-ethanediyl) bisbenzene, 4,4'-bis (1-oxo-2,4,5-triphenyl-cyclopenta-2,5-dien-3-yl)
1,1 '-(1,3-propanediyl) bisbenzene etc. can be mentioned. Among these biscyclopentadienone derivatives, a biscyclopentadienone derivative having a wholly aromatic skeleton is preferable from the viewpoint of heat resistance. These may be used alone or in combination of two or more.

The dienophile group is preferably an ethynyl group, and the compounds having three or more dienophile groups include 1,3,5-triethynylbenzene, 1,2,4.
-Triethynylbenzene, 1,3,5-tris (phenylethynyl) benzene, 1,2,4-tris (phenylethynyl) benzene, 1,2,3,5-tetrakis (phenylethynyl) benzene and the like. These may be used alone or in combination of two or more.

The Diels-Alder type polymerization reaction between the compound having two or more diene groups and the compound having three or more dienophile groups is preferably carried out by heating in a solvent. The solvent is not particularly limited as long as it is inert to this reaction, and mesitylene, γ-butyrolactone and the like are exemplified. The reaction conditions are 150-250
C., preferably 1 hour to 60 hours. It is preferable to carry out the polymerization reaction in a molar ratio of a diene group: a dienophile group of 1: 1 to 1: 3, more preferably 1: 1 to 1: 2, since polyphenylene excellent in heat resistance can be obtained. From the viewpoint of preventing gelation during the polymerization reaction, it is preferable that about 10% to 30% of all diene groups and dienophile groups be unreacted. The reaction rate is preferably controlled by the reaction temperature and time. The residual diene group and residual dienophile group in the polymer act as a crosslinkable functional group that reacts by heating after film formation, and at the same time, can be used as a reaction point with the silica precursor and / or the component (C).

The above-mentioned fluorine-containing polyarylene ether is
It is synthesized by a de-HF condensation polymerization reaction between a fluorine-containing aromatic ring-containing compound in which fluorine is directly bonded to an aromatic ring and a compound having two or more phenolic hydroxyl groups.

As the fluorine-containing aromatic ring-containing compound, those having a perfluoro aromatic ring are preferable, and perfluorobiphenyl, perfluoronaphthalene, perfluoroterphenyl, perfluoro (1,3,5-triphenylbenzene) and perfluoro (1,2,2,2). 5-triphenylbenzene) and the like. These may be used alone or in combination of two or more. Of these fluorine-containing aromatic ring-containing compounds, perfluoro (1,3,5-triphenylbenzene) and perfluoro (1,2,5-triphenylbenzene) having a branched structure are obtained, and the obtained fluorine-containing polyarylene ether is obtained. Is preferable because it has good heat resistance.

As the compound having two or more phenolic hydroxyl groups, polyfunctional phenols are preferable. Specific examples thereof include dihydroxybenzene, dihydroxybiphenyl, dihydroxyterphenyl, dihydroxynaphthalene, dihydroxyanthracene, dihydroxyphenanthracene, dihydroxy-9,9-diphenylfluorene, dihydroxydibenzofuran, dihydroxydiphenyl ether, dihydroxydiphenylthioether, dihydroxybenzophenone, dihydroxy. −
2,2-diphenylpropane, dihydroxy-2,2-
Diphenylhexafluoropropane, dihydroxybinaphthyl, tetraphenylhydroquinone, hexaphenyldihydroxybiphenyl, trihydroxybenzene,
Examples thereof include trihydroxybiphenyl, trihydroxynaphthalene, tetrahydroxybenzene, tetrahydroxybiphenyl, tetrahydroxybinaphthyl, tetrahydroxyspiroindanes and the like.

Among them, the obtained polymer has a low relative dielectric constant value and good heat resistance, and therefore, dihydroxybenzene, dihydroxy-9,9-diphenylfluorene, dihydroxy-2,2-diphenylhexafluoropropane, tetra Phenylhydroquinone and trihydroxybenzene are preferred.

The above-mentioned fluorine-containing polyarylene ether is
Furthermore, it is preferable to contain an ethynyl group as a crosslinkable functional group. The ethynyl group can be self-crosslinked by heat and can form a covalent bond with the silica precursor.
As a method of introducing an ethynyl group, a method of copolymerizing a monomer having an ethynyl group during the condensation polymerization reaction is preferable. Examples of the monomer having an ethynyl group include fluorine-containing arylacetylenes such as pentafluorophenylacetylene and nonafluorobiphenylacetylene, fluorine-containing diarylacetylenes such as phenylethynylpentafluorobenzene, phenylethynylnonafluorobiphenyl and decafluorotran, and phenylethynyl. Hydroxyl group-containing acetylenes such as phenol and dihydroxy tolan are included. These may be used alone or in combination of two or more.

The HF removing agent for the condensation polymerization reaction is preferably a basic compound, and particularly preferably an alkali metal carbonate, hydrogen carbonate or hydroxide. Specific examples include sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium hydroxide, potassium hydroxide and the like.

The amount of the catalyst used is required to be 1 time or more, preferably 1.1 to 3 times, the molar ratio of the phenolic hydroxyl group. The condensation polymerization reaction is preferably performed in a polar solvent. The polar solvent is preferably a solvent containing an aprotic polar solvent such as N, N-dimethylacetamide, N, N-dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide and sulfolane. The polar solvent may contain toluene, xylene, benzene, benzotrifluoride, xylenehexafluoride, etc. within a range that does not impair the solubility of the produced polymer and does not adversely affect the condensation polymerization reaction.

The polymerization reaction conditions are preferably 10 to 200 ° C. and 1 to 80 hours. More preferably 40 to 1
2 hours-60 hours at 80 ° C, most preferably 60-16
It is 3 hours to 24 hours at 0 ° C.

Heat-resistant organic polymer (B) in the present invention
The number average molecular weight of is preferably 500 to 500,000. Within this range, the compatibility with the silica precursor and the component (C) is good, and the domain size and average pore size of each component in the obtained porous nanocomposite thin film are small, and good. A film having excellent heat resistance, mechanical properties, chemical resistance and the like can be obtained. More preferably 1,0
00-100,000, most preferably 1,500-5
It is 10,000.

The silica precursor in the present invention forms a silica (A) represented by the above formula (1) by a catalyst such as an acid or an alkali, an oxidizing agent such as oxygen, or heat. It is preferable that one kind or two or more kinds selected from the group consisting of the alkoxysilanes represented by (2), (3) and (4) is partially hydrolyzed and condensed.

[0035] X¹X^TwoSi (OR¹)_Two        Formula (2) X^ThreeSi (OR^Two)_Three           Formula (3) Si (OR^Three)_Four              Formula (4) Where X¹, X^TwoAnd X^ThreeIs the same as the above formula (1)
It R¹, R^TwoAnd R ^ThreeIs hydrogen or C 1-8
Represents a rukyl group.

Specific examples of the alkoxysilane represented by the formula (2) include dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, dimethoxysilane, diethoxysilane, difluorodimethoxysilane and difluorodisilane. Examples include ethoxysilane. Even if these are used alone, 2
You may use it in mixture of 2 or more types. Dimethyldimethoxysilane and dimethyldiethoxysilane are preferred.

Specific examples of the alkoxysilane represented by the formula (3) include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane,
Ethyltriisopropoxysilane, octyltrimethoxysilane, octyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, trimethoxysilane, triethoxysilane, triisopropoxysilane, fluoro Examples include trimethoxysilane and fluorotriethoxysilane. These may be used alone or in combination of two or more. Methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, trimethoxysilane and triethoxysilane are preferred.

Specific examples of the alkoxysilane represented by the formula (4) include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane and tetrabutoxysilane. These may be used alone or in combination of two or more. Tetramethoxysilane and tetraethoxysilane are preferred.

The ratio of the alkoxysilane represented by the formula (2), the alkoxysilane represented by the formula (3), and the alkoxysilane represented by the formula (4) is a, b in the formula (1). And c.

The partial hydrolysis-condensation reaction of the alkoxysilanes represented by the formulas (2), (3) and (4) is preferably carried out by adding a catalyst and water. It is preferable to add 0.3 to 5.0 moles of water, and particularly preferable to add 0.5 to 2.0 moles of water per mole of the alkoxysilyl group. The amount of water added is 0.3-
Within the range of 5.0 mol, the uniformity of the obtained thin film can be maintained, and the storage stability of the composition for forming the thin film can be kept good.

Examples of the catalyst include organic acids, inorganic acids, organic basic compounds, inorganic basic compounds and the like. Examples of the organic acid 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, gallic acid. , Butyric acid, mellitic acid, arachidonic acid, 2-ethylhexanoic acid, oleic acid, stearic acid, linoleic acid, 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, sulfonic acid, phthalic acid, fumaric acid, citric acid, tartaric acid and the like. Examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, phosphoric acid and the like.

Examples of the organic basic compound include pyridine, pyrrole, piperazine, pyrrolidine, piperidine, picoline, trimethylamine, triethylamine,
Monoethanolamine, diethanolamine, dimethylmonoethanolamine, monomethyldiethanolamine, triethanolamine, diazabicyclooctane,
Examples thereof include diazabicyclononane, diazabicycloundecene, tetramethylammonium hydroxide and the like. Examples of the inorganic basic compound include ammonia, sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide and the like.
The amount of the catalyst used is 0.0001 to 1 in molar ratio with respect to the total amount of the compounds represented by the formulas (2), (3) and (4).
It is preferably 0.001 to 0.1.

The number average molecular weight of the silica precursor in the present invention is preferably 300 to 100,000. Within this range, the compatibility between the silica precursor and the heat-resistant organic polymer (B) and the compatibility between the silica precursor and the component (C) are good, and the resulting porous nanocomposite thin film contains Silica (A) and heat-resistant organic polymer (B) with a small domain size are obtained, and the average pore size is 10 μm.
Below, a thin film having good heat resistance, mechanical properties, chemical resistance and the like can be obtained. Preferably 500 to 50,0
00, more preferably 600 to 20,000.

The component (C) in the present invention is not particularly limited as long as it can be removed after the thin film is formed, (a) a substance which is volatilized by heat or a substance which is decomposed by heat and the decomposed product is volatilized, (B) A substance that decomposes by irradiation with electromagnetic waves such as ultraviolet rays or electron beams, and the decomposed product volatilizes, (c) a substance that elutes with a chemical liquid, or a substance that decomposes with a chemical liquid and the decomposed substance elutes Can be mentioned. Of these, the substances (a) and (b) are preferable because they are highly compatible with the manufacturing process of electronic components such as electronic devices and multilayer wiring boards.
The substance (a) is particularly preferable. Specific examples include compounds having a boiling point of 200 ° C. to 400 ° C. at atmospheric pressure, and thermally decomposable polymers.

Specific examples of the compound having a boiling point of 200 to 400 ° C. under normal pressure include amylbenzene, cyclohexylbenzene, dimethylnaphthalene, tetradecane, decalin, tetralin, decanol, undecanol, dodecanol, pentanediol, glycerin, dibutyl oxalate. , Dibutyl tartrate, dimethyl phthalate and the like.

The heat decomposable polymer is a polymer having a heat decomposition temperature of about 400 ° C. or lower, and particularly preferably a polymer having a heat decomposition temperature of 350 ° C. or lower. Here, the thermal decomposition temperature has the same definition as described in the heat resistant organic polymer (B). Specifically, aliphatic polyolefin, aliphatic polyether, aliphatic polyester,
Examples thereof include acrylic polymers and styrene polymers.
Among these, aliphatic polyethers, aliphatic polyesters, and acrylic polymers have good compatibility between the heat-resistant organic polymer (B) and the silica precursor, and a domain size of about 10 nm or less is obtained. It is preferable that the thermally decomposable polymer becomes porous with an average pore size of 10 nm or less after being decomposed and volatilized.

Further, those having a branched structure as a primary structure, such as dendrimers and star polymers, are also preferable. When a polymer having a branched structure is used, the volume occupied by the polymer is reduced, so that a porous material having an average pore diameter of 10 nm or less can be easily obtained. The number average molecular weight of the heat decomposable polymer is 300 to
100,000 is preferable and 500-2 is more preferable.
It is 10,000. When the number average molecular weight is within this range, the compatibility with the heat-resistant organic polymer (B) and the silica precursor is good, and a domain size of about 10 nm or less is obtained. As a result, the thermally decomposable polymer decomposes and decomposes. After volatilization, it is preferable because it becomes porous with an average pore size of 10 nm or less.

Heat-resistant organic polymer (B) in the present invention
Mass: The mass of silica (A) in terms of complete hydrolysis-condensation product (hereinafter referred to as reduced silica mass) is 5: 95-9.
5: 5 is preferable. Within this range, the resulting porous nanocomposite thin film has good chemical resistance and plasma resistance, and pores do not disappear due to softening of the heat-resistant organic polymer (B) during thermal crosslinking. A sufficient porosity can be obtained. More preferably 10:90 to 90:
It is 10.

The amount of the component (C) in the present invention is such that a sufficient porosity can be obtained, so that the heat-resistant organic polymer (B) is used.
Is preferably 5% by mass or more based on the total of the mass and the converted silica mass. Further, in order to maintain sufficient mechanical properties, it is preferably 300% by mass or less with respect to the total of the mass of the heat resistant organic polymer (B) and the converted silica mass. Further, it is preferably 10% by mass to 200% by mass.

Heat-resistant organic polymer (B) in the present invention
And (b) heat resistance between (a) the heat-resistant organic polymer (B) and the silica precursor in order to make the domain size of the silica (A) several tens of nm or less and the average pore size in the present invention to be 10 nm or less. It is preferable that at least two selected from the group consisting of the organic polymer (B) and the component (C) and (c) the silica precursor and the component (C) have an intermolecular interaction. Examples of the intermolecular interaction include covalent bond, ionic bond, hydrogen bond, π-π interaction, complex formation and electrostatic interaction. In particular,
At least two selected from the group consisting of (a), (b) and (c) above preferably have an intermolecular interaction due to a covalent bond or a hydrogen bond. The presence of such intermolecular interaction suppresses the phase separation of each component and reduces the domain size. As a result, a porous nanocomposite thin film having excellent mechanical properties, plasma resistance, and chemical resistance can be obtained.

As the intermolecular interaction between (a) the heat resistant organic polymer (B) and the silica precursor, a covalent bond is most preferable. This is because the covalent bond between the two improves the mechanical properties of the resulting porous nanocomposite thin film. As a method for covalently bonding both, the heat-resistant organic polymer (B) and the silica precursor can react with each other.
It suffices that each have at least one functional group, and known methods can be applied. As a specific example, an alkoxysilyl group is introduced into the heat-resistant organic polymer (B) and mixed with a silica precursor, or a co-hydrolysis reaction is performed with the heat-resistant organic polymer (B) during the synthesis of the silica precursor to form a siloxane bond. And a method of introducing an alkenyl group or alkynyl into the heat-resistant organic polymer (B) and reacting (hydrosilylation) a silica precursor containing a Si—H group. Among them, a method in which an ethynyl group is introduced into the heat resistant organic polymer (B) and a silica precursor containing a Si—H group is reacted is preferable.

The intermolecular interaction between the heat-resistant organic polymer (B) and the component (C) (b) is preferably a covalent bond or a hydrogen bond. Although various known methods can be adopted as the method, the case where a thermally decomposable polymer is used as the component (C) will be described below as an example. Examples of the method for imparting intermolecular interaction to the heat-resistant organic polymer (B) and the heat-decomposable polymer by covalent bonding include blocking or grafting of the heat-resistant organic polymer (B) and the heat-decomposable polymer. To be As the blocking or grafting method, known methods can be applied, for example, a method using a heat decomposable polymer having a site capable of reacting or copolymerizing with the heat resistant organic polymer (B) in the molecule, An example is a method of using a heat-resistant organic polymer (B) having a site for initiating polymerization or a site capable of reacting or copolymerizing with a thermally decomposable polymer in the molecule. As a specific example, a heat-resistant organic polymer (B) having a hydroxyl group in the side chain is synthesized, and ethylene oxide, which has the hydroxyl group as a starting site,
A method of obtaining a heat-resistant organic polymer (B) grafted with an aliphatic polyether, an aliphatic polyester or the like by ring-opening polymerization of propylene oxide, ε-caprolactone or the like can be mentioned.

A covalent bond or a hydrogen bond is preferred as the intermolecular interaction between (c) the silica precursor and the component (C). When the silica precursor has a silanol (Si-OH) group, a hydrogen bond is most preferable, and as the component (C),
It is preferable to use a compound containing a site capable of hydrogen bonding such as a hydroxyl group or a carbonyl group.

The intermolecular interaction preferably has a covalent bond in (a) or (b), particularly a covalent bond in (a) or (b), and a hydrogen bond in (c). Is most preferably present.

The porous nanocomposite thin film of the present invention comprises
Heat resistant organic polymer (B), silica precursor, component (C)
It can be obtained by forming a thin film from a composition containing a solvent and a solvent, and then removing the component (C).

The composition may be a mixture of the respective components, but a reaction product obtained by previously reacting the heat-resistant organic polymer (B) with a silica precursor via a covalent bond, or It is preferable to use a reaction product obtained by previously reacting the component (C) with the silica precursor via a covalent bond. As a specific method for preparing the composition, a method of blending a pre-synthesized heat-resistant organic polymer (B) with a reactant of a silica precursor, a component (C) and a solvent,
A method of blending a reactant of the heat-resistant organic polymer (B) synthesized in advance with the component (C), a silica precursor and a solvent,
Examples thereof include a method of producing a reactant of the heat-resistant organic polymer (B) and the silica precursor in the presence of the component (C) and / or a solvent.

After forming a thin film of the composition and before removing the component (C), it is preferable to fix the silica phase by gelling the silica precursor.

As the solvent, three components of the heat-resistant organic polymer (B), the silica precursor, and the component (C) are dissolved or dispersed, and the desired film thickness, uniformity, or embedding flatness is obtained by a desired method. There is no particular limitation as long as a thin film having is obtained, aromatic hydrocarbons, dipolar aprotic solvents,
Examples thereof include ketones, esters, ethers and halogenated hydrocarbons.

Examples of aromatic hydrocarbons include benzene, toluene, xylene, ethylbenzene, cumene, mesitylene, tetralin and methylnaphthalene.

Dipolar aprotic solvents include N-
Methylpyrrolidone, N, N-dimethylformamide,
N, N-dimethylacetamide, γ-butyrolactone,
Dimethyl sulfoxide and the like can be mentioned.

Examples of the ketones include methyl isobutyl ketone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone and methyl amyl ketone.

Examples of ethers include tetrahydrofuran, pyran, dioxane, dimethoxyethane, diethoxyethane, diphenyl ether, anisole, phenetole, diglyme, triglyme, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol. Examples include monobutyl ether.

Examples of the esters include ethyl lactate, methyl benzoate, ethyl benzoate, butyl benzoate, benzyl benzoate, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monoethyl ether acetate and the like.

Examples of the halogenated hydrocarbons include carbon tetrachloride, chloroform, methylene chloride, tetrachloroethylene, chlorobenzene and dichlorobenzene.

Heat-resistant organic polymer (B), silica (A)
The total concentration of (in terms of converted silica mass) and component (C) is 1
-80 mass% is preferred, and 5-60 mass% is more preferred.

As a method for forming the thin film, it is preferable to adopt a coating method on a suitable substrate. Examples thereof include known coating methods such as spin coating, dip coating, spray coating, die coating, bar coating, doctor coating, extrusion coating, scan coating, brush coating, and potting. When used as an insulating film for electronic devices,
From the viewpoint of film thickness uniformity, spin coating or scan coating is preferable.

The thickness of the thin film is preferably 0.01 to 50 μm, more preferably 0.1 to 30 μm.

The gelation of the silica precursor depends on the Si in the precursor.
It proceeds by a condensation reaction of —OH group, Si—OR group, and / or Si—H group. Examples of the method of advancing the condensation reaction include a method of heating and a method of exposing to an environment containing a basic catalyst and water. In the case of gelation by heating, the temperature is preferably 50 ° C. or higher, more preferably 100 ° C. or higher, and most preferably 150 ° C. or higher in order to allow the gelation to proceed sufficiently.

The method of exposing to an environment containing a basic catalyst and water is as follows:
In particular, it is preferably used for promoting the condensation reaction of Si-H groups. As the basic catalyst, ammonia, ammonium hydroxide and amines are preferable. As the amine, primary amine, secondary amine and tertiary amine can be used, and specific examples thereof include methylamine, ethylamine, butylamine, allylamine, dimethylamine, diethylamine, trimethylamine, triethylamine and the like. It is preferable to allow the condensation reaction to proceed by exposing the basic catalyst to an environment containing steam and steam.

The method for removing the component (C) is preferably heating or irradiation with electromagnetic waves as described above. It is also preferable to use heating and electromagnetic wave irradiation together. Examples of the atmosphere for heating and / or electromagnetic wave irradiation include an inert gas atmosphere such as nitrogen and argon, air, oxygen, reduced pressure, and the like, and an inert gas atmosphere and reduced pressure are preferable.

The heating conditions are 200 ° C. to 450 ° C. for 1 minute
120 minutes is preferable, 300 to 425 ° C for 2 minutes to 6
0 minutes is more preferred. In order to control the gelation reaction rate of the silica precursor and the removal rate of the component (C), or to secure the surface smoothness of the coating film and to improve the embeddability of the coating film in a fine space, 50 to 350 ° C It is also preferable to add a preliminary heating step to some extent or to carry out the heating step in several stages.

As the electromagnetic wave irradiation conditions, for example, when an electron beam is used, the irradiation energy is preferably 0.1 to 50 keV and the irradiation amount is preferably 1 to 1000 μC / cm ² .

When the component (C) is removed by heating, the condensation reaction of the gelled silica precursor further proceeds to form the silica skeleton represented by the above formula (1). By this step, a silica phase having substantially no Si-OH group or Si-OR group or a very small amount of silica phase is formed, which lowers the dielectric constant, increases the mechanical strength, and makes the hydrophobic state, which is preferable. Furthermore, when the heat-resistant organic polymer (B) has a self-crosslinkable functional group due to heat, the crosslinking reaction of this functional group proceeds, and the heat resistance and chemical resistance of the heat-resistant organic polymer (B) phase are increased. It is preferable because it improves.

The composition containing the heat-resistant organic polymer (B), silica precursor, component (C) and solvent in the present invention is preferably purified by a method such as neutralization, reprecipitation, extraction or filtration. . In applications related to electronic parts,
Metals such as potassium and sodium, which are condensation reaction catalysts, and liberated halogen atoms can be causative substances that cause malfunction of transistors and corrosion of wiring.

The applications of the porous nanocomposite thin film of the present invention include various insulating films, protective films, film materials for various batteries such as fuel cells, photoresists, antireflection films, optical waveguide materials, coating materials, electronic members. , Sealing agent, overcoat agent,
Examples include transparent film materials, adhesives, fibrous materials, weather resistant paints, water repellents, oil repellents, moisture-proof coating agents and the like. In particular, the use of an insulating film for electronic devices or an insulating film for multilayer wiring boards is preferable.

Electronic devices include individual semiconductors such as diodes, transistors, compound semiconductors, thermistors, varistors, and thyristors, DRAM (dynamic random access memory), SRAM (static
Random access memory), EPROM (erasable programmable read only memory),
Mask ROM (mask read only memory),
EEPROM (Electrical Erasable Programmable Read Only Memory), storage devices such as flash memory, microprocessor, DSP, A
Theoretical circuit elements such as SIC, MMIC (monolithic
An integrated circuit element such as a compound semiconductor represented by a microwave integrated circuit), a hybrid integrated circuit (Hybrid I)
C), light emitting diodes, photoelectric conversion elements such as charge-coupled elements, and the like.

The multilayer wiring board is various boards for mounting electronic devices and the like, and examples thereof include a printed wiring board, a build-up wiring board, and a high-density wiring board such as MCM.
Examples of the insulating film include a buffer coat film, a passivation film, an interlayer insulating film, an alpha ray shielding film and the like.

The porous nanocomposite thin film of the present invention comprises
It is also preferable to form a composite with another membrane. For example, when applied as a semiconductor device passivation film or a semiconductor device interlayer insulating film, it is preferable to form an inorganic film in the lower layer and / or upper layer of the porous nanocomposite thin film.

The inorganic film is a film formed by atmospheric pressure, reduced pressure or plasma chemical vapor deposition (CVD) method or coating method. For example, a silicon oxide film is doped with phosphorus and / or boron as necessary. So-called PSG film or BPSG
Examples thereof include a film, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a SiOC film, and a spin-on-glass (SOG) film.

By forming an inorganic film between the porous nanocomposite thin film of the present invention and the metal wiring, peeling of the metal wiring can be prevented, and etching processing such as a damascene shape can be facilitated. It is also preferable that the inorganic film is formed on the upper layer of the porous nanocomposite thin film after the porous nanocomposite thin film is partially removed by an etch back method or a CMP (Chemical Mechanical Polishing) method.

When an inorganic film is formed on the upper layer of the porous nanocomposite thin film of the present invention, if the adhesion between the porous nanocomposite thin film and the inorganic film is not sufficient, or if oxygen ashing is used when removing the photoresist after etching. If the film may be damaged, it is preferable to treat the surface of the porous nanocomposite thin film with energy rays. As the energy ray treatment, electromagnetic waves in a broad sense including light, that is, UV light irradiation, laser light irradiation, microwave irradiation, or the like, or processing using an electron beam, that is, electron beam irradiation, glow discharge treatment, corona discharge treatment ,
Processing such as plasma processing is exemplified.

Among these, as a treatment method suitable for the mass production process of semiconductor elements, UV light irradiation, laser light irradiation, corona discharge treatment, and plasma treatment can be mentioned. Plasma treatment is more preferable because it gives less damage to the semiconductor element.
The apparatus for performing the plasma treatment is not particularly limited as long as a desired gas can be introduced into the apparatus and an electric field can be applied, and a commercially available barrel type or parallel plate type plasma generator can be used as appropriate. The gas introduced into the plasma device is not particularly limited as long as the surface can be effectively treated, and examples thereof include argon, helium, nitrogen, oxygen, and mixed gas thereof. The treatment with nitrogen plasma is preferable because a dense nitride layer is formed on the extreme surface of the porous nanocomposite thin film and it has an effect of preventing damage to the film due to oxygen ashing when removing the photoresist.

[0083]

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited thereto. Examples 1-
14 is a synthesis example, Examples 15 to 24, 29 and 30 are Examples, and Examples 25 to 28 are Comparative Examples.

The molecular weights in Examples 1 to 13 are polystyrene-equivalent number average molecular weights measured by gel permeation chromatography (GPC) using tetrahydrofuran as a carrier solvent.

Example 1 Synthesis of heat-resistant organic polymer In a flask having a capacity of 1 L, 18.90 g of perfluoro (1,3,5-triphenylbenzene), 8.32 g of 4-phenylethynylnonafluorobiphenyl, 1,3 , 5
-3.78 g of trihydroxybenzene, 279 of N, N-dimethylacetamide (hereinafter DMAc).
I charged g. While stirring, the mixture was heated on an oil bath, and when the liquid temperature reached 60 ° C, 27.3 g of potassium carbonate was quickly added, and the mixture was heated at 60 ° C for 4 hours while continuing stirring. Then, the reaction solution was cooled to room temperature and gradually added to 2 L of a pure water / methanol (volume ratio about 1/1) mixed solution containing about 30 g of acetic acid, which was vigorously stirred to precipitate a white powder. The white powder was filtered, washed with pure water 5 times, and vacuum dried at 80 ° C. for 15 hours to obtain a white powder polymer (hereinafter referred to as P1). The molecular weight of P1 was about 5,000.

[Example 2] Synthesis of heat-resistant organic polymer In a flask having a capacity of 100 ml, 3,3 '-(oxydi-
2.35 g of 1,4-phenylene) bis (2,4,5-triphenylcyclopentadienone), 1.14 g of 1,3,5-tris (phenylethynyl) benzene and γ
-Prepare 8.5 g of butyrolactone, and in a nitrogen atmosphere,
Heated at 200 ° C. for 48 hours. After cooling to about 100 ° C., cyclohexanone was added so that the solid content concentration was 20% by mass to obtain a polymer solution having a molecular weight of about 6,000 (hereinafter referred to as P2).

Example 3 Synthesis of heat-resistant organic polymer In a flask having a capacity of 1 L, 18.9 g of perfluoro (1,3,5-triphenylbenzene), 10.72 g of pentafluorotran, and 1,3,5-tri were prepared. 5.04 g of hydroxybenzene and 312 g of DMAc were charged. While stirring, the mixture was heated on an oil bath, and when the liquid temperature reached 60 ° C, 36.4 g of potassium carbonate was quickly added, and the mixture was heated at 60 ° C for 4 hours while continuing stirring. Then, the reaction solution was cooled to room temperature and gradually added to about 1 L of 1N hydrochloric acid water which was vigorously stirred, whereby a white powdery substance was precipitated. The white powder was filtered, washed with pure water 5 times, and vacuum dried at 80 ° C. for 15 hours to obtain a white powder polymer (hereinafter referred to as P3). The molecular weight of P3 is 3,500
Met.

[Example 4] Synthesis of silica precursor 5.
00 g, 16.40 g of methyltrimethoxysilane and 39.07 g of cyclohexanone were charged. While vigorously stirring at room temperature, 6.68 g of a 1% maleic acid aqueous solution was added dropwise over about 40 minutes, and after completion of the addition, the mixture was heated at 60 ° C. for 2 hours. After that, the total weight is 48.8g using an evaporator.
It concentrated until it became, and the solid content density | concentration (complete hydrolyzate conversion) obtained the silica precursor solution (henceforth S1) of 20 mass%. The molecular weight was about 1,200.

Example 5 Synthesis of Silica Precursor A flask having a capacity of 200 ml contained 8.02 g of tetramethoxysilane and 25.66 g of methyltrimethoxysilane.
And propylene glycol monopropyl ether 6
3.64 g was charged. 1% with vigorous stirring at room temperature
12.70 g of maleic acid aqueous solution was added dropwise over about 50 minutes, and after completion of the addition, the mixture was heated at 60 ° C. for 2 hours. Then, the mixture was concentrated using an evaporator until the total weight became 77.8 g, to obtain a silica precursor solution (hereinafter referred to as S2) having a solid content concentration (complete hydrolyzate conversion) of 20% by mass. The molecular weight was about 1,000.

Example 6 Synthesis of Pyrolysable Polymer 1.2 ml of ethylene glycol was added to a 50 ml flask.
4 g, 22.82 g of ε-caprolactone and 0.01 g of tin (II) 2-ethylhexanoate were charged. By heating at 120 ° C. for 20 hours in a nitrogen atmosphere, polycaprolactone (hereinafter referred to as D1) having two hydroxyl groups as terminal groups in the molecule was obtained. Molecular weight is about 1,2
It was 00.

Example 7 Synthesis of Thermally Decomposable Polymer Instead of ethylene glycol, 2.27 'of 2,2'-bis (hydroxymethyl) -1,3-propanediol was used.
In the same manner as in Example 6 except that g was used, polycaprolactone having four hydroxyl groups as terminal groups in the molecule (hereinafter referred to as D
2 ) Got. The molecular weight was about 1,100.

[Example 8] Synthesis of heat decomposable polymer In the same manner as in Example 6 except that 1.89 g of ethylene glycol monotertiary butyl ether was used instead of ethylene glycol, a hydroxyl group as a terminal group in the molecule was 1 Polycaprolactone (hereinafter referred to as D3)
Got The molecular weight was 1,700.

Example 9 Synthesis of Reactant of Heat-Resistant Organic Polymer and Silica Precursor Solution obtained by dissolving 0.50 g of the polymer P1 obtained in Example 1 in 2.85 g of cyclohexanone and Example 4. 5.10 g of the obtained silica precursor solution S1 was added to a volume of 25 ml.
The flask was charged and the system was replaced with nitrogen gas. 3 μl of platinum divinyltetrasiloxane complex (3% solution in toluene) was added thereto and heated at 70 ° C. for 2 hours. Further, 4 μl of platinum divinyltetrasiloxane complex (3% solution in toluene) was added and heated at 75 ° C. for 1 hour to obtain a reactant solution of the heat resistant organic polymer and the silica precursor (hereinafter referred to as PS1).

Example 10 Synthesis of Reactant of Heat-Resistant Organic Polymer and Silica Precursor Polymer solution P2 obtained in Example 2 (5.00 g) and silica precursor solution S1 obtained in Example 4 (5). 00 g was charged into a flask having a capacity of 25 ml, and the inside of the system was replaced with nitrogen gas. 5 μl of platinum divinyltetrasiloxane complex (3% toluene solution) was added thereto, and heated at 75 ° C. for 2 hours to obtain a reactant solution of the heat-resistant organic polymer and the silica precursor (hereinafter referred to as PS2). .

Example 11 Synthesis of Reactant of Heat-Resistant Organic Polymer and Silica Precursor 3.0 g of the polymer P3 obtained in Example 3 was mixed with 1 part of toluene.
The solution dissolved in 7 g and triethoxysilane of 0.
59 g was charged into a flask having a capacity of 50 ml, and the inside of the system was replaced with nitrogen gas. 20 μl of platinum divinyltetrasiloxane complex (3% solution in toluene) was added thereto, and heated at 80 ° C. for 2 hours. After cooling, a white powder obtained by gradually adding the reaction solution to a large excess of hexane was added to 80 ° C.
After vacuum drying for 15 hours, a polymer containing a triethoxysilyl group (hereinafter referred to as P4) was obtained.

Polymer P4 0.95 g, tetraethoxysilane 1.2 g, methyltriethoxysilane 3.
68 g and 20 g of cyclohexanone with a capacity of 100 m
It was charged in a 1-liter flask and stirred at room temperature to obtain a uniform solution. With vigorous stirring at room temperature, 1.57 g of a 1% maleic acid aqueous solution was added dropwise over about 40 minutes, and after completion of the addition, the mixture was heated at 60 ° C. for 2 hours. After that, it was concentrated to a total weight of 14.8 g using an evaporator, and a reaction solution of the heat-resistant organic polymer and the silica precursor (hereinafter referred to as PS
3).

Example 12 Synthesis of Reactant of Heat-Resistant Organic Polymer and Thermally Decomposable Polymer 25.11 g of polymer D3 obtained in Example 8 was dissolved in 100.4 g of tetrahydrofuran, and the volume was 300 ml.
I put it in the flask. Here, 10.3 of pyridine
g, 20.99 g of hexamethyldisilazane and 14.1 g of chlorotrimethylsilane were charged and reacted at 50 ° C. for 20 hours in a nitrogen atmosphere. After the volatile matter was distilled off, 78.9 g of dichloromethane was added and dissolved. After insoluble matter was removed by suction filtration using filter paper, volatile matter was distilled off to obtain polycaprolactone having a trimethylsilyloxy group at the terminal.

2.5 g of the present polycaprolactone and 2.5 g of the polymer P1 obtained in Example 1 were dissolved in 20 g of dimethylformamide and charged into a flask having a volume of 50 ml. Further, 0.75 g of cesium fluoride was charged and heated under nitrogen at 70 ° C. for 4 hours. After cooling, 8.0 g of trifluoroacetic acid was added, and the mixture was stirred at room temperature for 10 hours.
The white powdery polymer was recovered by pouring it into a large amount of about 0.1 N hydrochloric acid water, and vacuum-dried at 80 ° C. for 12 hours to obtain a reaction product of the heat-resistant organic polymer and the heat-decomposable polymer (hereinafter referred to as PD1 I got).

Example 13 Synthesis of Reactant of Heat Resistant Organic Polymer and Thermally Decomposable Polymer 3.0 g of polymer P1 obtained in Example 1, 0.78 g of 2- (4-hydroxyphenyl) ethyl alcohol, D
Charge 27 g of MAc into a 50 ml volume flask and
The solution was stirred at 0 ° C to obtain a uniform solution. At this temperature, 1.2 g of potassium carbonate was charged all at once, and heating was continued at 60 ° C. for 6 hours under stirring. After cooling, the white powdery polymer was recovered by pouring it into a large amount of about 1N hydrochloric acid water, and vacuum-dried at 80 ° C. for 12 hours to obtain a polymer having a primary hydroxyl group in the molecule.

0.6 g of the present polymer, 1.8 g of ε-caprolactone and 0.004 g of tin (II) 2-ethylhexanoate were placed in a 20 ml capacity flask. By heating at 120 ° C. for 20 hours in a nitrogen atmosphere,
A polymer (hereinafter referred to as PD2) in which polycaprolactone was grafted on the heat-resistant organic polymer P1 was obtained. The molecular weight was 10,000.

[Example 14] In the presence of a thermally decomposable polymer,
Synthesis of reaction product of heat-resistant organic polymer and silica precursor 1.00 g of polymer P4 obtained in Synthesis Example 11, 3.47 g of tetraethoxysilane, polymethylmethacrylate (manufactured by Aldrich, molecular weight about 15,000) 1.
00g and 12g of methyl isobutyl ketone in a volume of 5
A uniform solution was prepared by charging the mixture in a 0 ml flask and stirring at room temperature. Further, 20 g of 0.01% maleic acid aqueous solution was charged, and the mixture was vigorously stirred at room temperature for about 1 hour. After that, the methyl isobutyl ketone layer is separated and concentrated to a total weight of 15 g using an evaporator to give a reactant solution containing a thermally decomposable polymer, a heat resistant organic polymer and a silica precursor (hereinafter referred to as PSD1). I got).

Example 15 Reactant solution PS1 of the heat-resistant organic polymer and silica precursor obtained in Example 9 (mass of heat-resistant organic polymer: reduced silica mass is 3: 7, total solid content concentration Was dissolved in 12.6 parts by mass of the thermally decomposable polymer D1 obtained in Example 6 to 100 parts by mass of 18% by mass) to prepare a composition having a composition ratio shown in Table 1. here,
As the silica precursor, the converted silica mass was used. The composition was filtered through a PTFE filter having a pore size of 0.2 μm,
550n by spin coating on a 4-inch silicon wafer
m thin film was formed. 150 ℃ × 1 on the hot plate
After preheating at 250 ° C. for 180 seconds for 80 seconds, heating (baking) was performed at 425 ° C. for 1 hour in a vertical furnace in a nitrogen atmosphere. The results of the following evaluation of the obtained porous nanocomposite thin film are shown in Table 1.

Relative permittivity: SSM-495 manufactured by SSM was used to measure the CV with a mercury prober to determine the relative permittivity of 1 MHz. The film thickness used the value calculated by the spectroscopic ellipsometer. Mechanical strength: DCM-SA2 manufactured by MTS was used to measure the elastic modulus by the nanoindentation method. Average pore size: ATX-G manufactured by Rigaku Denki Co., Ltd. was used to determine the average pore size in the porous thin film by the X-ray small angle scattering method.

Further, a phase structure of 30 nm or more was not observed by scanning electron microscope observation of the cross section of the thin film. The refractive index value of the thin film at 630 nm determined by spectroscopic ellipsometer measurement was 1.28. On the other hand, the refractive index of the film obtained by only PS1 containing no heat-decomposable polymer D1 under the same coating conditions was 1.43. This decrease in the refractive index value means that an air phase (refractive index value 1) exists in the film,
That is, it shows that it is porous, and the porosity is calculated as 35% as follows. (1.43-1.28) ÷ (1.43-1) × 100 =
35.

[Examples 16 to 28] Compositions containing the silica precursor, the heat resistant organic polymer, the heat decomposable polymer and the solvent in the composition ratios shown in Table 1 using the raw materials shown in Table 1 Was adjusted. In Example 27 cyclohexanone was used as the solvent. A thin film was formed from these compositions by the same method as in Example 15, and the film characteristics were evaluated. The solid content concentration and spin rotation number of the composition were adjusted so that the film thickness was in the range of 400 to 700 nm. When it was necessary to dilute the composition by adjusting the solid content concentration, cyclohexanone was used as a diluting solvent. The results are shown in Table 1.

When the cross sections of the thin films obtained in Examples 16 to 27 were observed with a scanning electron microscope, no phase structure of 30 nm or more was observed. Further, although the composition of Example 28 was uniformly transparent, roughening and white turbidity of the film, which is considered to be caused by phase separation of μm order or more, were observed during spin coating.
It was not possible to evaluate the film characteristics (it was described in the table that it could not be evaluated).

[0107]

[Table 1]

[Example 29] Evaluation as interlayer insulating film (stability of laminated structure) From the solution composition prepared in Example 19, silicon wafer / p-SiO (300 nm) / porous nanocomposite thin film ( 500 nm) / p-SiN (50 nm)
A laminated film of / p-SiO (500 nm) was created.

A silicon wafer having a p-SiO film (thickness of 300 nm) formed thereon is spin-coated with a solution to have a thickness of 50.
A 0 nm porous nanocomposite thin film was formed as in Example 14. Next, a silicon nitride film is formed to a thickness of 50 nm with a mixed gas of monosilane, ammonia and nitrogen, and then 500 nm is added with a mixed gas of monosilane and oxygen dinitride.
A thick silicon oxide film was formed.

The obtained laminate was baked at 425 ° C. for 60 minutes in a hydrogen atmosphere, and the crack resistance to thermal stress was examined with a metallurgical microscope. No cracks or other defects were found.

Example 30 Evaluation as Interlayer Insulating Film (Microfabrication and Chemical Resistance) The solution composition prepared in Example 19 was spin-coated under the same conditions as in Example 14 to give a film thickness on a silicon wafer. A 400 nm porous nanocomposite thin film was formed.
After forming a photoresist on this and patterning by photolithography, RIE (reactive ion.
The porous nanocomposite thin film was etched by the etching method. Photoresist stripping solution EKC265
When the coating film that had been subjected to the cleaning process (trade name, manufactured by EKC) was examined with a metallurgical microscope, no defects were observed. The relative dielectric constant value was 2.1, which was unchanged from the value immediately after film formation. That is, it was confirmed that there was no damage to the porous nanocomposite thin film due to the fine processing and the resist removing process.

[0112]

The porous nanocomposite thin film of the present invention has a low relative permittivity and excellent mechanical properties represented by elastic modulus. Since the porous nanocomposite thin film has high resistance to plasma treatment and cleaning treatment during the manufacturing process of the insulating film for electronic devices and the insulating film for multilayer wiring boards, the porous nanocomposite thin film is used as an insulating film for electronic devices and insulating films for multilayer wiring boards. Excellent applicability.

Claims (5)

[Claims] 1. A porous nanocomposite thin film containing silica (A) and a heat-resistant organic polymer (B) and having a mean pore size of 10 nm or less. 2. The porous nanocomposite thin film according to claim 1, wherein the heat resistant organic polymer (B) is a polymer having an aromatic ring-containing repeating unit. 3. The porous nanocomposite thin film according to claim 1, wherein the heat resistant organic polymer (B) is a polymer containing fluorine. 4. A thin film is formed from a composition containing a precursor of silica (A), a heat resistant organic polymer (B), a component (C) which can be removed after the thin film is formed, and a solvent, and then the above component (C). The method for forming a porous nanocomposite thin film according to any one of claims 1 to 3, wherein: 5. A heat-resistant organic polymer (B) between a precursor of silica (A), (b) a heat-resistant organic polymer (B) and a component (C), and (c) silica. The method for forming a porous nanocomposite thin film according to claim 4, wherein at least two selected from the group consisting of the precursor of (A) and the component (C) have an intermolecular interaction.