JP2003253205A - Siliceous film-forming composition, method for producing siliceous film and electronic part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for forming a siliceous film having excellent low dielectric properties and sufficient mechanical strength and curable at a lower temperature and/or a shorter time than those of a conventional composition. <P>SOLUTION: The composition for forming the siliceous film comprises (a) a siloxane resin such as an alkoxysilane, (b) a solvent such as an alcohol capable of dissolving the siloxane resin and (c) a polymer having hydroxy groups in the side chain so as to satisfy the relationship represented by formula (2) 0<MOH<0.4×10<SP>-2</SP>(2) (wherein, MOH denotes the concentration (mol/g) of hydroxy groups in the polymer). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art With regard to electronic device parts such as semiconductor elements such as LSIs, the increase in signal delay time due to increase in inter-wiring capacitance has become a problem with the miniaturization of wiring due to high integration. Heat resistance to materials,
In addition to mechanical properties, further low relative permittivity and shortening of heat treatment process are required.

Generally, the signal propagation velocity (v) of the wiring and the relative permittivity (ε) of the insulating material with which the wiring material is in contact are expressed by the following equation (3); v = k / √ε (3) (Wherein k is a constant). That is, by increasing the frequency range to be used and reducing the relative permittivity (ε) of the insulating material, high speed signal propagation can be achieved. For example, conventionally, the relative dielectric constant is 4.2.
Although a SiO ₂ film formed by the CVD method to some extent has been used as a material for forming an interlayer insulating film, a further lower dielectric constant is used from the viewpoint of reducing the interwiring capacitance of the device and improving the operation speed of the LSI. There is a long-felt need for material to emerge.

On the other hand, as a low dielectric constant material that has been put into practical use at present, there is a SiOF film formed by a CVD method having a relative dielectric constant of about 3.5. Further, as an insulating material having a relative dielectric constant of 2.5 to 3.0, organic SOG is used.
(Spin On Glass), an organic polymer, etc. can be illustrated. Furthermore, as an insulating material having a relative dielectric constant of 2.5 or less, a porous material having voids in the film is considered to be effective, and a study for applying it to an interlayer insulating film of an LSI
Development is actively done.

As a method for forming such a porous material,
JP-A-11-322992, JP-A-11-310
Japanese Patent No. 411 and the like propose a reduction in the dielectric constant of an organic SOG material. In this method, a film is formed from a composition containing a polymer having a property of volatilizing or decomposing by heating with a hydrolysis-polycondensation product of a metal alkoxysilane, and pores are formed by heating the film. is there.

[0006]

However, in such a conventional method, the film strength tends to decrease as the dielectric constant of the insulating film decreases, which is a serious problem from the viewpoint of process compatibility. Further, in order to cure the coating film of the composition, a high temperature atmosphere of 450 ° C. or higher is required,
Moreover, since it tends to take a long time of about 1 hour until the curing is finally completed, when this film is used as an interlayer insulating film, the heat input amount (thermal budget) in the formation process causes other layers, In particular, the deterioration of the wiring layer is concerned. Further, there may be a problem that the warp of the substrate becomes remarkable as the amount of heat input increases.

Further, as described above, miniaturization of wiring is accelerated due to high integration, thinning / multilayering of each member layer constituting a device, and material change of wiring layers and the like are progressing. In order to deal with this, it is expected that the influence of material deterioration of each layer due to heat input will increase more than ever, and there is an urgent need to improve the heat history by reducing the heat load in each process.

Therefore, the present invention has been made in view of the above circumstances, and is excellent in low dielectric properties and has sufficient mechanical strength, and is cured at a low temperature and / or a short time as compared with conventional ones. It is an object of the present invention to provide a composition for forming a silica-based coating capable of being produced, a method for producing a silica-based coating, and an electronic component having the silica-based coating.

[0009]

In order to solve the above problems, the inventors of the present invention have conducted extensive studies from the viewpoint of material components and compositions for obtaining a silica-based coating film as an insulating film, and have studied specific components. It has been found that a composition containing the above can solve various conventional problems, and has completed the present invention.

That is, the composition for forming a silica-based coating film according to the present invention is obtained by hydrolyzing and condensing a compound represented by component (a): the following formula (1); R ¹ _n SiX _4-n (1) The siloxane resin thus obtained, the component (b): a solvent capable of dissolving the component (a), and the component (c): a polymer having a side chain containing a hydroxyl group are components (c). The polymer satisfies the relationship represented by the following formula (2); 0 <M _OH <0.4 × 10 ^-2 (2).

In the formula (1), R ¹ is H atom or F atom, or B atom, N atom, Al atom, P atom or S atom.
a group containing an i atom, a Ge atom or a Ti atom, or an organic group having 1 to 20 carbon atoms, X represents a hydrolyzable group,
n represents an integer of 0 to 2, and when n is 2, each R ¹ may be the same or different, and when n is 0 to 2, each X may be the same or different. Also, in equation (2), M
_OH represents the concentration (mol / g) of the hydroxyl group in the polymer which is the component (c).

The composition having such a structure is applied onto a substrate such as a wafer and then cured by heating to form a silica-based film (Low-k film) exhibiting a low dielectric constant. At this time, since the side chain of the polymer as the component (c) contains a hydroxyl group, phase separation between the siloxane resin as the component (a) and the polymer is caused when the solvent as the component (b) evaporates. As a result, the pores formed inside the film are miniaturized and the shape is made uniform. Not only that, decomposition of the component (c) is suppressed during heating, and its volatilization is promoted.

The component (c) has a temperature of 300 to 500.
It is suitable that the reduction rate in a nitrogen gas atmosphere at 0 ° C. is 95% by mass or more, more preferably 97% by mass or more, and further preferably 99% by mass or more. When such a component (c) is used, it is possible to sufficiently prevent the polymer or the reaction product derived from the polymer from remaining in the finally obtained silica-based coating when the composition is heated. To be done.

Further, it is more preferable that the component (c) contains an ester bond in the molecule. in this case,
The decomposition or volatilization of the polymer when the composition is heated is further promoted.

Specifically, the component (c) contains a (meth) acrylic acid derivative as a constituent component, and the content concentration of the (meth) acrylic acid derivative is 0.5 × 10 ^-2 (m
ol / g) or more is useful. This has the advantage of further promoting the decomposition or volatilization of the polymer when the composition is heated.

More specifically, the component (a) comprises H atom, F atom, B atom, N atom, and A per mol of Si atom.
The total content of at least one atom selected from the group consisting of 1 atom, P atom, Si atom, Ge atom, Ti atom, and C atom is preferably 0.65 mol or less, more preferably 0.55 or less, It is preferably 0.50 or less, particularly preferably 0.45 or less. The lower limit of the total content ratio is preferably about 0.20. In this way, the adhesion of the silica-based coating to other films (layers) and the reduction in mechanical strength are suppressed.

Further, in the method for producing a silica-based coating film according to the present invention, the composition for forming a silica-based coating film of the present invention is applied on a substrate, the solvent contained in the applied coating film is removed, and then the coating film is applied to 250 It is characterized by firing at a heating temperature of ~ 500 ° C.

Further, the electronic component (device) according to the present invention has an insulating film formed on a substrate on which an element structure is formed, and the insulating film is produced by the method for producing a silica-based coating of the present invention. The above-mentioned silica-based coating, or one containing the silica-based coating.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. As described above, the composition for forming a silica-based film according to the present invention includes the components (a) and (b) as essential components.
It includes a component and a component (c).

<Component (a)> The component (a) is a siloxane resin obtained by hydrolyzing and condensing a compound represented by the following formula (1); R ¹ _n SiX _4-n (1) . Here, in the formula, R ¹ is H atom or F atom, or B atom, N atom, Al atom, P atom, Si
An atom, a group containing a Ge atom or a Ti atom, or an organic group having 1 to 20 carbon atoms, X represents a hydrolyzable group, and n
Represents an integer of 0 to 2, and when n is 2, each R ¹ may be the same or different, and when n is 0 to 2, each X may be the same or different.

Examples of the hydrolyzable group X include an alkoxy group, a halogen atom, an acetoxy group, an isocyanate group and a hydroxyl group. Among these,
Alkoxy groups are preferred from the viewpoints of liquid stability of the composition itself, coating properties, and the like.

Examples of the compound (alkoxysilane) of the formula (1) in which the hydrolyzable group X is an alkoxy group include, for example, tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane and tetra-iso-propoxysilane. , Tetra-n-butoxysilane, tetra-s
ec-butoxysilane, tetra-tert-butoxysilane, tetraalkoxysilane such as tetraphenoxysilane, trimethoxysilane, triethoxysilane, tripropoxysilane, fluorotrimethoxysilane, fluorotriethoxysilane, methyltrimethoxysilane,
Methyltriethoxysilane, methyltri-n-propoxysilane, methyltri-iso-propoxysilane, methyltri-n-butoxysilane, methyltri-iso-
Butoxysilane, methyltri-tert-butoxysilane, methyltriphenoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltri-n-
Propoxysilane, ethyltri-iso-propoxysilane, ethyltri-n-butoxysilane, ethyltri-
iso-butoxysilane, ethyltri-tert-butoxysilane, ethyltriphenoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltri-n-propoxysilane, n-propyltri-iso-propoxysilane , N-propyltri-n-butoxysilane, n-propyltri-iso
-Butoxysilane, n-propyltri-tert-butoxysilane, n-propyltriphenoxysilane, is
o-propyltrimethoxysilane, iso-propyltriethoxysilane, iso-propyltri-n-propoxysilane, iso-propyltri-iso-propoxysilane, iso-propyltri-n-butoxysilane, iso-propyltri-iso -Butoxysilane,
iso-propyltri-tert-butoxysilane, i
so-propyltriphenoxysilane, n-butyltrimethoxysilane, n-butyltriethoxysilane, n-
Butyltri-n-propoxysilane, n-butyltri-
iso-propoxysilane, n-butyltri-n-butoxysilane, n-butyltri-iso-butoxysilane, n-butyltri-tert-butoxysilane, n-
Butyltriphenoxysilane, sec-butyltrimethoxysilane, sec-butyltriethoxysilane, se
c-Butyltri-n-propoxysilane, sec-butyltri-iso-propoxysilane, sec-butyltri-n-butoxysilane, sec-butyltri-iso
-Butoxysilane, sec-butyltri-tert-butoxysilane, sec-butyltriphenoxysilane,
t-butyltrimethoxysilane, t-butyltriethoxysilane, t-butyltri-n-propoxysilane, t
-Butyltri-iso-propoxysilane, t-butyltri-n-butoxysilane, t-butyltri-iso-
Butoxysilane, t-butyltri-tert-butoxysilane, t-butyltriphenoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltri-n-propoxysilane, phenyltri-is.
o-propoxysilane, phenyltri-n-butoxysilane, phenyltri-iso-butoxysilane, phenyltri-tert-butoxysilane, phenyltriphenoxysilane, trifluoromethyltrimethoxysilane, pentafluoroethyltrimethoxysilane, 3,
3,3-trifluoropropyltrimethoxysilane,
Trialkoxysilane such as 3,3,3-trifluoropropyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldi-n-propoxysilane, dimethyldi-iso-propoxysilane, dimethyldi-n-butoxysilane, dimethyldi- s
ec-butoxysilane, dimethyldi-tert-butoxysilane, dimethyldiphenoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldi-n-propoxysilane, diethyldi-iso-propoxysilane, diethyldi-n-butoxysilane, diethyldi-sec. -Butoxysilane, diethyldi-tert
-Butoxysilane, diethyldiphenoxysilane, di-
n-propyldimethoxysilane, di-n-propyldiethoxysilane, di-n-propyldi-n-propoxysilane, di-n-propyldi-iso-propoxysilane, di-n-propyldi-n-butoxysilane, di- n
-Propyldi-sec-butoxysilane, di-n-propyldi-tert-butoxysilane, di-n-propyldiphenoxysilane, di-iso-propyldimethoxysilane, di-iso-propyldiethoxysilane, di-
iso-propyldi-n-propoxysilane, di-is
o-propyldi-iso-propoxysilane, di-is
o-propyldi-n-butoxysilane, di-iso-propyldi-sec-butoxysilane, di-iso-propyldi-tert-butoxysilane, di-iso-propyldiphenoxysilane, di-n-butyldimethoxysilane, di- n-butyldiethoxysilane, di-n-butyldi-n-propoxysilane, di-n-butyldi-is
o-propoxysilane, di-n-butyldi-n-butoxysilane, di-n-butyldi-sec-butoxysilane, di-n-butyldi-tert-butoxysilane, di-n-butyldiphenoxysilane, di-sec -Butyldimethoxysilane, di-sec-butyldiethoxysilane, di-sec-butyldi-n-propoxysilane, di-sec-butyldi-iso-propoxysilane, di-
sec-Butyldi-n-butoxysilane, di-sec-
Butyldi-sec-butoxysilane, di-sec-butyldi-tert-butoxysilane, di-sec-butyldiphenoxysilane, di-tert-butyldimethoxysilane, di-tert-butyldiethoxysilane, di-
tert-butyldi-n-propoxysilane, di-te
rt-butyldi-iso-propoxysilane, di-te
rt-butyldi-n-butoxysilane, di-tert-
Butyldi-sec-butoxysilane, di-tert-butyldi-tert-butoxysilane, di-tert-butyldiphenoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldi-n-
Propoxysilane, diphenyldi-iso-propoxysilane, diphenyldi-n-butoxysilane, diphenyldi-sec-butoxysilane, diphenyldi-ter.
t-butoxysilane, diphenyldiphenoxysilane,
Bis (3,3,3-trifluoropropyl) dimethoxysilane, methyl (3,3,3-trifluoropropyl)
Examples thereof include diorganodialkoxysilane such as dimethoxysilane.

As the compound (halogenated silane) of the formula (1) in which the hydrolyzable group X is a halogen atom (halogen group), the alkoxy group in each of the above alkoxysilane molecules is substituted with a halogen atom. There are some. Further, examples of the compound (acetoxysilane) of the formula (1) in which the hydrolyzable group X is an acetoxy group include those in which the alkoxy group in each of the above alkoxysilane molecules is substituted with an acetoxy group. Furthermore, examples of the compound of formula (1) in which the hydrolyzable group X is an isocyanate group (isocyanate silane) include those in which the alkoxy group in each of the above alkoxysilane molecules is substituted with an isocyanate group. Furthermore, examples of the compound (hydroxysilane) of the formula (1) in which the hydrolyzable group X is a hydroxyl group include those in which the alkoxy group in each of the above alkoxysilane molecules is substituted with a hydroxyl group.

The compounds represented by the formula (1) may be used alone or in combination of two or more kinds.

Further, as a catalyst for promoting the hydrolytic condensation reaction in the hydrolytic condensation of the compound represented by the formula (1), formic acid, maleic acid, fumaric acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid , Heptanoic acid,
Octanoic acid, nonanoic acid, decanoic acid, oxalic acid, adipic acid, sebacic acid, butyric acid, oleic acid, stearic acid, linoleic acid, linoleic acid, salicylic acid, benzoic acid, p-
Aminobenzoic acid, p-toluenesulfonic acid, phthalic acid,
Organic acids such as sulfonic acid, tartaric acid and trifluoromethanesulfonic acid, and inorganic acids such as hydrochloric acid, phosphoric acid, nitric acid, boric acid, sulfuric acid and hydrofluoric acid can be used.

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

Further, in this reaction, alcohol by-produced by hydrolysis may be removed by using an evaporator or the like, if necessary. Furthermore, the amount of water to be present in the hydrolysis-condensation reaction system can be appropriately determined, and the amount of water is 0.5 to 20 relative to 1 mol of the compound represented by the formula (1). A value within the range of moles is preferable. When the amount of water is less than 0.5 mol or more than 20 mol, the film-forming property of the silica-based coating may be deteriorated and the storage stability of the composition itself may be deteriorated.

Further, the siloxane resin as the component (a) is used in view of solubility in a solvent, mechanical properties, moldability, etc.
Gel permeation chromatography (hereinafter "G
"PC") and converted using a standard polystyrene calibration curve to give a mass average molecular weight of 500
To 20,000, preferably 1,000 to 1
It is more preferably 10,000. When this mass average molecular weight is less than 500, the film forming property of the silica-based coating tends to be poor. On the other hand, when the mass average molecular weight exceeds 20,000, the compatibility with the solvent tends to decrease.

Further, H atom, F atom, B atom, N atom bonded per silicon atom of the siloxane resin,
The total number (M) of at least one atom selected from the group consisting of Al atom, P atom, Si atom, Ge atom, Ti atom, and C atom (hereinafter referred to as "specific bond atom") is 0.65 or less. It is preferably 0.55 or less, more preferably 0.50 or less, particularly preferably 0.45 or less, and very preferably 0.45 or less. The lower limit value is preferably about 0.20.

The total number (M) of the specific bond atoms is 0.
If it exceeds 65, the adhesion and mechanical strength of the finally obtained silica-based coating with other films (layers) tend to be poor.
On the other hand, if the total number (M) is less than 0.20, the dielectric properties when used as an insulating film tend to be poor. Also,
Among these specific bonding atoms, the siloxane resin is a H atom, an F atom, an N atom in view of the film forming property of the silica-based film.
It is more preferable to include at least one kind of atom, Si atom, Ti atom and C atom, and among them, H atom, F atom, N atom, Si atom and C atom in terms of dielectric properties and mechanical strength. It is more preferable to include at least one of the above.

The total number (M) can be obtained from the charged amount of the siloxane resin which is the component (a). For example, the following formula (4); M = (M1 + (M2 / 2) + (M3 / 3)) / Msi ... (4) can be calculated using the relationship. In the formula, M1 represents the total number of atoms bonded to a single (only) Si atom of a specific bond atom, and M2 is shared by two silicon atoms of the specific bond atom. The total number of atoms present, M3 shows the total number of atoms shared by three silicon atoms among the specific bond atoms, and Msi shows the total number of Si atoms.

<Component (b)> The component (b) is a solvent capable of dissolving the component (a), that is, the above-mentioned siloxane resin, and includes, for example, methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, s
ec-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, s
ec-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, phenol, Cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, 1,2
-Propylene glycol, 1,3-butylene glycol, diethylene glycol, dipropylene glycol,
Alcoholic solvents such as triethylene glycol and tripropylene glycol, acetone, methyl ethyl ketone,
Methyl-n-propyl ketone, methyl-n-butyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, methyl-n-hexyl ketone, diethyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclohexanone, cyclopenta Non, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, diacetone alcohol, acetophenone, γ-
Ketone-based solvent such as butyrolactone, ethyl ether, i
So-propyl ether, n-butyl ether, n-hexyl ether, 2-ethylhexyl ether, ethylene oxide, 1,2-propylene oxide, dioxolane, 4-methyldioxolane, dioxane, dimethyldioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether. , Ethylene glycol diethyl ether, ethylene glycol mono-n-
Hexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, ethylene glycol dibutyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl 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, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, tetrahydrofuran, ether solvents such as 2-methyltetrahydrofuran, methyl acetate,
Ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate,
N-Pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, nonyl acetate, γ-butyrolactone, γ-valero. Lactone, methyl acetoacetate, ethyl acetoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene acetate Glycol monoethyl ether, propylene glycol monopropyl ether acetate, dipropylene glycol monomethy acetate Ether, dipropylene glycol monoethyl ether acetate, glycol diacetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, i-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, Examples thereof include ester solvents such as ethyl lactate, n-butyl lactate and n-amyl lactate, and solvents such as acetonitrile, N, N-dimethylformamide, N, N-dimethylacetamide and N, N-dimethylsulfoxide. These may be used alone or in combination of two or more.

As the amount of the solvent (that is, the component (b)) used, the amount of the component (a) (siloxane resin) in the mixed solution of the component (a) and the component (b) is 3 to 25% by mass. Such an amount is preferable. When the amount of the solvent is too small and the concentration of the component (a) exceeds 25% by mass, the film-forming property of the silica-based coating film and the like tend to deteriorate and the stability of the composition itself tends to decrease. On the other hand, when the amount of the solvent is excessive and the concentration of the component (a) is less than 3% by mass, it tends to be difficult to form a silica-based coating film having a desired film thickness.

<Component (c)> The component (c) has a side chain containing a hydroxyl group, and the concentration M _OH (mol / g) of the hydroxyl group in the side chain is represented by the following formula (2); 0 <M _OH <0.4 × 10 ^-2 (2), which is a polymer satisfying the relationship.

When the concentration M _OH of this hydroxyl group is 0 (zero) mol / g, that is, when the side chain contains no hydroxyl group, (a) when the solvent is removed from the composition by volatilization or the like. The component siloxane resin and the polymer may be phase-separated. In this case, the pore size of the finally obtained silica-based coating becomes excessively large,
There is a tendency that the diameter distribution spreads and the uniformity of the fine pores deteriorates, which may lead to a decrease in mechanical strength. On the other hand, when the hydroxyl group concentration M _OH exceeds 0.4 × 10 ^-2 mol / g, the polymer becomes difficult to decompose or volatilize during heating,
There is an inconvenience that the heat treatment requires a high temperature or a long time.

Here, the concentration of hydroxyl group M _OH (mo
1 / g) can be determined from the charged amount of the polymer,
For example, it can be calculated using the relationship represented by the following formula (5); M _OH = (Ma × Mb / Mb) / Mh × 100 (5). In the formula, Ma represents the molar ratio of the minimum repeating unit containing a hydroxyl group, Mb represents the molecular weight of the hydroxyl group (OH group), and Mh represents the average molecular weight of the polymer.

The polymer as the component (c) has a temperature of 3
The reduction rate in a nitrogen gas atmosphere of 00 to 500 ° C. is 95.
It is preferably at least mass%, more preferably 97
It is at least mass%, more preferably at least 99 mass%. If this reduction rate is less than 95% by mass, decomposition or volatilization of the polymer when heating the composition tends to be insufficient, and the polymer in the finally obtained silica-based coating film,
A part of the polymer or a reaction product derived from the polymer may remain. In this case, the electrical properties of the silica-based coating may be deteriorated, such as an increase in the relative dielectric constant.

The "reduction rate" of the polymer (c) in the present invention is a value determined by the following apparatus and conditions.・ Used device: TG / DTA6300 (manufactured by Seiko Instruments Inc.) ・ Temperature increase start temperature: 50 ° C ・ Rate increase rate: 10 ° C / min ・ Sample amount: 10 mg ・ Atmosphere: Nitrogen (N ₂ ) gas 200 ml / min ・ Reference: α-Alumina (manufactured by Seiko Instruments) ・ Sample container: Open sample pan φ5 Aluminum (manufactured by Seiko Instruments)

The reference mass of the polymer (c) before the start of decomposition is the mass at 150 ° C. during heating. This is because the decrease in mass at 150 ° C. or lower is due to the removal of adsorbed water and the like, and it is estimated that the decomposition of the polymer itself, which is the component (c), has not substantially occurred. In addition, in the measurement of the "reduction rate", when the polymer as the component (c) cannot be directly weighed out due to the fact that the polymer is dissolved in the solution, the solution containing the polymer is used. For example, about 2 g is placed in a metal petri dish, and the residue obtained by drying in atmospheric air at 150 ° C. for 3 hours is used as a sample.

Further, the polymer as the component (c) is
From the viewpoint of compatibility with the siloxane resin as the component (a), the mass average molecular weight measured by GPC and converted using a calibration curve of standard polystyrene is 500 to 1
It is preferably 0,000, and 1,000 to 5
It is more preferably 10,000. When this mass average molecular weight is less than 500, the film forming property of the silica-based coating tends to be poor. On the other hand, the mass average molecular weight is 100,000.
If it exceeds, the compatibility with the siloxane resin tends to decrease.

Specific examples of the compound (monomer component) having a hydroxyl group which constitutes the polymer of the component (c) are acrylic acid, 2-hydroxyethyl acrylate, diethylene glycol acrylate and 2-hydroxypropyl acrylate. , Dipropylene glycol acrylate, methacrylic acid, 2-hydroxyethyl methacrylate, diethylene glycol methacrylate, 2
-(Meth) acrylic acid derivatives such as hydroxypropyl methacrylate and dipropylene glycol methacrylate, vinyl alcohol, allyl alcohol and the like.

The polymer as the component (c) may contain a compound having no hydroxyl group as a constituent component for the purpose of adjusting the concentration M _OH of the hydroxyl group in the side chain. Examples of such compounds having no hydroxyl group include vinyl ether compounds, vinyl compounds having a polyethylene oxide structure, vinyl compounds having a polypropylene oxide structure, vinyl pyridine compounds, styrene compounds, and alkyl ester vinyl compounds. Examples thereof include compounds and (meth) acrylate acid compounds. Among these, a compound having an ester bond is preferable from the viewpoint of excellent decomposition property or volatility property of the polymer, and a (meth) acrylate acid compound ((meth) acrylate acid derivative) is particularly preferable.

As the (meth) acrylate acid derivative,
Examples thereof include acrylic acid esters or methacrylic acid esters such as acrylic acid alkyl ester, methacrylic acid alkyl ester, acrylic acid alkoxyalkyl ester, methacrylic acid alkyl ester, and methacrylic acid alkoxyalkyl ester.

As alkyl acrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n acrylate
-Butyl, isobutyl acrylate, pentyl acrylate, hexyl acrylate, and other alkyl esters having 1 to 6 carbon atoms are mentioned. As the methacrylic acid alkyl ester, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, methacrylic acid can be mentioned. Carbon number 1 to 1 such as isopropyl, n-butyl methacrylate, isobutyl methacrylate, pentyl methacrylate, and hexyl methacrylate.
6 alkyl ester.

Furthermore, examples of the alkoxyalkyl acrylate include methoxymethyl acrylate and ethoxyethyl acrylate, and examples of the methoxyalkoxyalkyl methacrylate include methoxymethyl methacrylate and ethoxyethyl methacrylate.

It is desirable that the composition for forming a silica-based coating film of the present invention does not contain an alkali metal or an alkaline earth metal, and even if it is contained, the metal ion concentration in the composition is 100 ppb or less. Preferably 20
It is more preferably ppb or less. If the concentration of these metal ions exceeds 100 ppb, the metal ions may easily flow into the semiconductor element having the silica-based coating film obtained from the composition, which may adversely affect the device performance itself. Therefore, it is effective to remove an alkali metal or an alkaline earth metal from the composition by using an ion exchange filter or the like, if necessary.

Such a silica-based film-forming composition is
As will be described later, it is applied on a substrate such as a wafer and then cured by heating and baking, whereby a silica-based coating (Low-k film) that exhibits a low dielectric constant is formed. At this time, since a hydroxyl group is contained in the side chain of the polymer as the essential component (c), when the solvent of the component (b) is removed by volatilization or the like, the siloxane resin of the component (a) Phase separation from the polymer is prevented, and the pores formed inside the film are made finer and the shape is made uniform.

Therefore, it is possible to prevent the mechanical strength of the finally obtained silica coating film from being lowered. Further, by setting the total number of bonding atoms in the siloxane resin to be 0.65 or less, a further sufficient mechanical strength can be realized, and moreover, sufficient adhesiveness with another film (layer) can be secured. Therefore, the wiring metal such as Cu deposited on the silica-based coating is replaced by C
It is possible to prevent interfacial peeling in the process of MP (Chemical Mechanical Polish).

Further, since the concentration of the hydroxyl group in the side chain of the polymer which is the component (c) is not more than the above upper limit value, the decomposition of the component (c) is suppressed during heating and its volatilization is promoted. It Therefore, it becomes possible to cure the composition at a low temperature or at a short time as compared with the conventional method, without making the temperature excessively high. As a result, the amount of heat input to the substrate can be significantly reduced, the deterioration of the characteristics of other films (layers) and thus the device can be suppressed, and the throughput can be improved by shortening the process time.

As a method for forming a silica-based coating on a substrate using such a composition for forming a silica-based coating of the present invention, a spin coating method which is excellent in film-forming property and film uniformity of the silica-based coating is generally used. Take for example. First, the composition for forming a silica-based coating film is preferably applied on a substrate such as a silicon wafer at 500 to 5000 rpm, more preferably 1
Spin coating at 000-3000 rpm to form a coating. At this time, if the rotation speed is less than 500 rotations / minute,
While the film uniformity tends to deteriorate, 5000 revolutions /
If the amount exceeds the limit, the film formability may be deteriorated, which is not preferable.

Next, the solvent in the coating is dried on a hot plate or the like at preferably 50 to 300 ° C., more preferably 100 to 300 ° C. If the drying temperature is lower than 50 ° C, the solvent tends to be insufficiently dried. On the other hand, when the drying temperature is higher than 300 ° C., the porous polymer (component (c)) is thermally decomposed before the siloxane skeleton is formed in the coating film, and the volatilization amount undesirably increases. It may be difficult to obtain a silica-based coating film having desired mechanical strength and low dielectric properties.

Next, the coating film from which the solvent has been removed is applied to 250 to 5
Final baking is performed by firing at a heating temperature of 00 ° C. The final curing is preferably performed in an inert atmosphere of N ₂ , Ar, He or the like, and in this case, the oxygen concentration is preferably 1000 ppm or less. When the heating temperature is less than 250 ° C,
There is a tendency that sufficient curing cannot be achieved and that decomposition and volatilization of the component (c) cannot be promoted sufficiently. On the other hand, if the heating temperature exceeds 500 ° C., the amount of heat input may increase and the wiring metal may deteriorate if there is a metal wiring layer.

The heating time at this time is preferably 2 to 60 minutes, more preferably 2 to 30 minutes. If this heating time exceeds 60 minutes, the amount of heat input may excessively increase and the wiring metal may deteriorate. Further, as the heating device, it is preferable to use a heat treatment device such as a quartz tube furnace or other furnace, a hot plate, and rapid thermal annealing (RTA).

The thickness of the silica coating film thus formed is preferably 0.01 to 40 μm, more preferably 0.1 μm to 2.0 μm. When the film thickness exceeds 40 μm, cracks tend to occur due to stress, while when it is less than 0.01 μm,
When metal wiring layers are present above and below the silica-based coating, the leak characteristics between the upper and lower wirings tend to deteriorate.

Examples of the electronic component of the present invention having such a silica coating include devices having an insulating film such as semiconductor elements and multilayer wiring boards. Specifically, in a semiconductor element, it can be used as a surface protective film (passivation film), a buffer coat film, an interlayer insulating film, or the like. On the other hand, in a multilayer wiring board, it can be preferably used as an interlayer insulating film.

More specifically, as semiconductor elements, individual semiconductors such as diodes, transistors, compound semiconductors, thermistors, varistors and thyristors, DRAMs (dynamic random access memories), SRAMs.
(Static Random Access Memory), E
PROM (erasable programmable read only memory), mask ROM (mask read
Only memory), EEPROM (Electrical erasable programmable read only)
Memory), flash memory and other storage elements, microprocessors, DSP, ASIC and other theoretical circuit elements,
MMIC (monolithic microwave integrated circuit)
Examples thereof include integrated circuit elements such as compound semiconductors, hybrid integrated circuits (hybrid ICs), light emitting diodes, photoelectric conversion elements such as charge-coupled elements, and the like. Examples of the multilayer wiring board include high density wiring boards such as MCM.

By including the silica-based coating film of the present invention exhibiting a low dielectric constant, such an electronic component can achieve high performance such as reduction of signal propagation delay time and at the same time high reliability.

[0058]

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

<Synthesis Example 1> A polymer as the component (c) was synthesized by the following procedure. First, 300 g of propylene glycol monomethyl ether acetate (PGMEA) was charged into a 1000 ml flask, and azobisisobutyronitrile (AIBN) was added to a 200 ml dropping funnel.
After charging 95 g of methyl methacrylate in which 0 g was dissolved and 5 g of 2-hydroxyethyl methacrylate and replacing the inside of the system with nitrogen gas, while heating and stirring in a 130 ° C. oil bath under a nitrogen gas atmosphere, the contents in the dropping funnel were changed. Solution 2
It dripped in the flask over time.

Then, after stirring for 30 minutes, 97.8 PGMEA in which 0.2 g of AIBN was dissolved in a dropping funnel.
g preparation and dropping into the flask over 1 hour. After the dropping, the mixture was stirred for 2 hours and then returned to room temperature to obtain a polymer solution.

From these charged amounts, the side chain hydroxyl group concentration M _OH calculated using the above-mentioned formula (5) is
It was 0.038 × 10 ^-2 mol / g. Also, GPC
When the mass average molecular weight was measured by the method, it was 9,800.
Met. Further, 2 g of the polymer solution was weighed into a metal petri dish and dried in a drier at 150 ° C. for 3 hours to obtain a polymer concentration of 16.7 mass%. Furthermore, 500 measured using the obtained polymer dried product.
The mass reduction rate at ° C was 99%.

Example 1 Tetraethoxysilane 13
2.3 g and 65.1 g of methyltriethoxysilane were mixed with propylene glycol monopropyl ether (PGP) 3
In the solution dissolved in 35.94 g, 70% nitric acid 0.9
65.8 g of water in which 2 g was dissolved was added dropwise under stirring over 30 minutes. After completion of dropping, reaction was carried out for 5 hours to obtain a polysiloxane solution. Polymer solution 2 obtained in Synthesis Example 1 was added to this solution.
29.6 g was added, and the produced ethanol was distilled off in a warm bath under reduced pressure to prepare a silica-based film-forming composition of the present invention consisting of 630 g of a polysiloxane / polymer solution.

<Synthesis Example 2> A polymer as the component (c) was synthesized by the following procedure. First, 300 g of PGP was charged into a 1000 ml flask, and methyl methacrylate 4 in which 1.7 g of AIBN was dissolved in a 200 ml dropping funnel.
After charging 5 g and 55 g of 2-hydroxyethyl methacrylate and replacing the system with nitrogen gas, the solution in the dropping funnel was placed in the flask over 2 hours while stirring under heating in an oil bath at 130 ° C. under a nitrogen gas atmosphere. Was added dropwise. Then, after stirring for 30 minutes, AIBN 0.
97.8 g of PGP in which 17 g was dissolved was charged and dropped into the flask over 1 hour. After the dropping, the mixture was stirred for 2 hours and then returned to room temperature to obtain a polymer solution.

From these charged amounts, the side-chain hydroxyl group concentration M _OH calculated using the above equation (5) is
It was 0.48 mol / g. In addition, the mass average molecular weight was measured by GPC method and found to be 10,700. Further, 2 g of the polymer solution was weighed out on a metal petri dish and dried in a dryer at 150 ° C. for 3 hours to obtain a polymer concentration of 15.0% by mass. Furthermore, the mass reduction rate at 500 ° C. measured using the obtained dried polymer was 95%.

Comparative Example 1 The polymer solution 2 obtained in Synthesis Example 2 was added to the polysiloxane solution prepared in the same manner as in Example 1.
55.6 g was added, and the produced ethanol was distilled off in a warm bath under reduced pressure to prepare a silica-based film-forming composition comprising 650 g of a polysiloxane / polymer solution.

Comparative Example 2 Polyvinyl acetate (mass average molecular weight: 12,000, mass reduction rate at 500 ° C .: 9) was added to a polysiloxane solution prepared in the same manner as in Example 1.
2%, hydroxyl group concentration M _OH : 0 mol / g) 2
191.7 g of a 0 wt% PGP solution was added, and the produced ethanol was distilled off in a warm bath under reduced pressure to prepare a silica-based film-forming composition comprising 600 g of a polysiloxane / polymer solution.

<Production of Interlayer Insulating Film> Example 1 and comparison
The number of revolutions of each of the silica-based film-forming compositions obtained in Examples 1 and 2
Spin coating on silicon wafer at 2000 rpm / 30 seconds
To form a film. After spin coating, 150 ℃ / 1 minute +2
After removing the solvent in the coating at 50 ° C. for 1 minute, ₂Dark
Quartz chew whose degree is controlled around 100 ppm
Finally, the coating is finally cured in a furnace at 400 ° C for 30 minutes.
A silica-based coating as an inter-insulating film was manufactured.

<Evaluation of Interlayer Insulating Film> The obtained interlayer insulating films were evaluated for film thickness, electrical characteristics, and film strength by the following methods.

[Measurement of Film Thickness] The film thickness of each interlayer insulating film is measured by a spectroscopic ellipsometer (manufactured by Gartner Co .; ellipsometer L1).
16B, wavelength used: 633 nm). Specifically, the interlayer insulating film was irradiated with He—Ne laser light, and the film thickness obtained from the phase difference caused by the irradiation at the designated wavelength was measured.

[Measurement of relative permittivity] The “relative permittivity” of the film in the present invention means a value measured in an atmosphere of 23 ° C. ± 2 ° C. and a humidity of 40% ± 10%, which is Al metal and N type. This was done by measuring the charge capacity between the low resistivity substrates (Si wafer). Specifically, on the obtained interlayer insulating film, Al metal was formed into a circle having a diameter of 2 mm and a thickness of about 0.1 μm by a vacuum vapor deposition apparatus.
It was vacuum-deposited so as to be m. As a result, the insulating film is
A structure disposed between the metal and the low resistivity substrate is formed. Next, the charge capacity of this structure was measured by an LF impedance analyzer (Yokogawa Denki Co., Ltd .: HP4192A) and a dielectric test fixture (Yokogawa Denki: HP16).
451B) is used, the operating frequency is 1MHz
It was measured at.

Then, the measured value of the charge capacity is expressed by the following formula (6); relative dielectric constant of the interlayer insulating film = 3.597 × 10 ⁻² × charge capacity (pF) × film thickness (μm) (6) , And the relative dielectric constant of the interlayer insulating film was calculated.

[Measurement of Elastic Modulus] MT for each interlayer insulating film
A nanoindenter DCM manufactured by S Co. was used to measure the elastic modulus indicating the film strength.

The results of the above measurements are shown in Table 1 together with the physical properties of the polymer.

[0074]

[Table 1]

[0075]

As explained above, according to the composition for forming a silica-based coating film and the method for producing a silica-based coating film of the present invention, it has excellent low dielectric properties and sufficient mechanical strength, and It is possible to cure at a lower temperature and / or a shorter time than in the conventional case. This makes it possible to form a silica-based coating suitable as an interlayer insulating film and the like.
The heat history can be improved by reducing the heat input to the substrate. Therefore, it is possible to suppress deterioration of each layer that constitutes an electronic component such as an element, particularly a wiring layer. Further, since the electronic component according to the present invention has such a silica-based coating, it is possible to improve the electrical reliability of the entire device, and it is possible to improve the yield of product production and the process margin. Moreover, due to the excellent properties of the silica-based coating, it is possible to provide an electronic component having high density, high quality and excellent reliability.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09D 183/04 C09D 183/04 201/08 201/08 H01L 21/312 H01L 21/312 C 21/768 21 / 90 Q (72) Inventor Koichi Abe 4-13-1, Higashi-machi, Hitachi City, Ibaraki Hitachi Chemical Co., Ltd. Research Laboratory (72) Inventor Shigeru Nobe 4-13-1, Higashi-cho, Hitachi City, Ibaraki Prefecture Hitachi Kasei Kogyo Co., Ltd. Yamazaki Plant F-term (reference) 4G072 AA25 BB09 EE07 GG02 HH29 JJ47 LL15 MM01 MM36 RR03 RR13 UU30 4J038 AA011 CE012 CE022 CG142 CH122 DL021 DL031 GA03 GA04 NA11 WR3QRQ09H03QRQR11H11QQQQQQQQQQQQQQQQQQU WW04 XX03 XX14 XX24 XX27 5F058 AA08 AA10 AC03 AD05 AF04 AG01 AH02 AH03 BA10 BA20 BC05 BD07 BE01 BF46 BH04 BJ02 BJ03

Claims (7)

[Claims] 1. A component (a): the following formula (1); R ¹ _n SiX _4-n (1), (wherein R ¹ is an H atom or an F atom, or a B atom,
A group containing an N atom, an Al atom, a P atom, a Si atom, a Ge atom or a Ti atom, or an organic group having 1 to 20 carbon atoms, X represents a hydrolyzable group, and n represents an integer of 0 to 2. When n is 2, each R ¹ may be the same or different, and when n is 0 to 2, each X may be the same or different). The siloxane resin thus obtained, the component (b): a solvent capable of dissolving the component (a), and the component (c): a polymer having a side chain containing a hydroxyl group. , The following formula (2); 0 <M _OH <0.4 × 10 ^-2 (2), M _OH : Concentration (mol / g) of the hydroxyl group in the polymer, which satisfies the relationship Which is a silica-based film-forming composition. 2. The component (c) has a temperature of 300 to 500.
The composition for forming a silica-based coating film according to claim 1, which has a reduction rate of 95% by mass or more in a nitrogen gas atmosphere at 0 ° C. 3. The silica-based film-forming composition according to claim 1, wherein the component (c) contains an ester bond in the molecule. 4. The (c) component is (meth) acrylic acid
A derivative is included as a constituent component, and the (meth)
Acrylic acid derivative content concentration is 0.5 × 10 ^-2(Mol
/ G) or more, any one of Claims 1-3.
The composition for forming a silica-based coating film according to 1. 5. The component (a) comprises H atom, F atom, B atom, N atom, Al atom and P atom per mol of Si atom.
5. The total content of at least one atom selected from the group consisting of atoms, Si atoms, Ge atoms, Ti atoms, and C atoms is 0.65 mol or less, according to any one of claims 1 to 4. The silica-based film-forming composition as described above. 6. A silica-based coating film forming composition according to claim 1 is applied onto a substrate, the solvent contained in the applied coating film is removed, and then the coating film is applied to 250 ~
A method for producing a silica-based coating, which comprises firing at a heating temperature of 500 ° C. 7. An electronic component in which an insulating film is formed on a substrate on which an element structure is formed, wherein the insulating film is a silica-based coating manufactured by the method for manufacturing a silica-based coating according to claim 6. An electronic component characterized by being included.