JP2003163210A - Manufacturing method of insulating thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a porous silica thin film having a low relative dielectric constant of a porous silica thin film and having sufficient mechanical strength to withstand a CMP step in a copper wiring step of a semiconductor element. SOLUTION: A coating composition for an insulating thin film containing a silica precursor containing at least one compound selected from an alkoxysilane having a specific structure and a hydrolyzate and a polycondensate thereof, an organic polymer and a solvent is provided. Porous silica characterized by gelling a silica precursor after being coated twice on a substrate under specific conditions to form a silica / organic polymer composite, and then removing the organic polymer from the thin film Manufacturing method of thin film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an insulating thin film having a sufficiently low relative permittivity and an extremely high mechanical strength.

[0002]

2. Description of the Related Art Porous silica is widely used as a structural material, a catalyst carrier, an optical material and the like because it has excellent properties such as light weight and heat resistance. For example, in recent years, expectations have been gathered from the viewpoint that porous silica can lower the dielectric constant. Conventionally, a dense silica film has been generally used as an insulating thin film material for a multilayer wiring structure of a semiconductor device such as an LSI. However, in recent years, the wiring density of LSIs has been miniaturized, and the distance between adjacent wirings on the substrate has been narrowed accordingly. At this time, if the dielectric constant of the insulator is high, the capacitance between the wirings increases, and as a result, the delay of the electric signal transmitted through the wiring becomes significant, which is a problem. In order to solve such a problem, a material having a lower dielectric constant is strongly required as a material for an insulating film for a multilayer wiring structure. On the other hand, the fact that copper having a lower resistance has begun to be used as a wiring material in place of conventional aluminum is another reason why a substance having a lower dielectric constant is required.

In Japanese Patent Laid-Open No. 5-85762 and International Publication (WO) 99/03926, a mixture system of a general alkoxysilane and an organic polymer has an extremely low dielectric constant, uniform pores and pore distribution. There is disclosed a method for obtaining porous silica having a porosity. Further, JP-A-4-285081 discloses a method in which a sol-gel reaction of alkoxysilane is carried out in the presence of a specific organic polymer to obtain porous silica having a uniform pore size.

However, in any of the methods, porous silica having a sufficiently low relative dielectric constant, stability over time, and sufficient mechanical strength to withstand the CMP process has not been obtained. . In the present invention, C
The MP step is a step of polishing the surface of excess copper on the insulating thin film to planarize it when the copper to be the wiring is embedded in the groove in the insulating thin film formed by the etching process. In this step, not only the insulating thin film, but also the barrier thin film on the thin film (usually depositing hundreds to thousands of Å silicon oxide on the insulating thin film) is subjected to compressive stress and shear stress, Mechanical strength is required for the insulating thin film.

Further, generally, when an organic polymer is to be removed from these silica / organic polymer composites by heating, a heating temperature of 450 ° C. or higher is a major constraint on the semiconductor device manufacturing process. For example, in consideration of oxidation and crystal growth of metal wiring, thermal stress and the like in the semiconductor element manufacturing process, the upper limit of the heating temperature is around 400 ° C. and a non-oxidizing atmosphere is recommended. However, under these heating conditions, most of the organic polymer in the silica / organic polymer composite remains or becomes char, and for example, when a multilayer wiring structure is created, the gas derived from the organic polymer remaining in the lower layer is It may occur from the lower layer and cause a decrease in the adhesive strength of the upper layer or peeling.

In order to solve this problem, means of using an organic polymer which is easily decomposed thermally has been studied, but the organic polymer is too sensitive to heat and the handling is extremely dangerous, or the sol-gel reaction catalyst is used. The molecular weight is lowered due to the deterioration of the film-forming property, and the poor compatibility with the silica precursor causes precipitation in the coating solution, and the film is densified by decomposition / volatilization during film-forming. The problem of
The preparation of porous silica has been difficult.

[0007]

DISCLOSURE OF THE INVENTION The present invention is to solve the above problems, and particularly when a porous silica thin film is used as an insulating thin film, the relative dielectric constant is low and stable, and the mechanical strength is high. High, CMP in copper wiring process of semiconductor element
It is intended to provide a method of manufacturing an insulating thin film that can sufficiently withstand the process.

[0008]

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, (A) an electrically insulating / curable inorganic component or organic component, (B) a temperature range of 0 to 500 ° C. The coating composition containing at least one substance capable of volatilizing or generating a gas by heat at (C) and the organic solvent (C) is coated on a substrate to remove the solvent in the coating film before and after the treatment.
The present invention has been completed by finding that a thin film obtained by removing 0% by weight or more and 99% by weight or less, then applying the coating again, and subsequently curing and porosifying solves the above problems.

The above and other objects, characteristics and benefits of the present invention will be apparent from the detailed description and claims below. That is, the present invention is: (A) an electrically insulating inorganic or organic component,
An insulating thin film is produced through the following steps 1 to 3 using a coating composition containing (B) a substance capable of volatilizing or generating gas by heat in a temperature range of 0 to 500 ° C. and (C) an organic solvent. A method of manufacturing an insulating thin film, comprising: Step 1: A step of applying the coating composition to the surface of the base material. Step 2: A step of removing the solvent in the coating film obtained by coating from 10% by weight to 99% by weight before and after the treatment, and then re-coating the coating composition in the same manner as in step 1. Step 3: A step of removing the component (B) after curing the component (A) in the coating film obtained in the step 2. 2.1 (A), (B) and (C) components,
(A) The following general formula (1) and / or general formula (2)
A silica precursor containing at least one compound selected from the group consisting of alkoxysilanes represented by the formula and a hydrolyzate or polycondensate thereof, and R ¹ _n (Si) (OR ² ) _4-n (1) (formula In the formula, R ¹ represents hydrogen or a monovalent organic group, and R ² is 1
-Valent organic group, n is an integer of _{^{0~3) R 3 m (R 4}} O) 3-m Si- (R 7) p -Si (OR 5) 3-q R 6 q (2) (R ³ and R ⁶ may be the same or different and represent hydrogen or a monovalent organic group, R ⁴ and R ⁵ may be the same or different and each represents a monovalent organic group, m And q, which may be the same or different, each represents a number of 0 to 2, R ⁷ represents a group represented by an oxygen atom-or (CH ₂ ) r-, r is 1 to 6, and p is 0 or 1.) (B) at least one organic solvent selected from the group consisting of linear or branched organic polymers, (C) alcohol-based solvents, ketone-based solvents, amide-based solvents and ester-based solvents 2. The method for producing an insulating thin film described in 1 above. The organic polymer according to 3.2 is linear or branched 2
2. The insulating thin film according to 1, wherein at least one of the original block copolymer and the organic polymer end group has at least one organic polymer having a group chemically inactive to the silica precursor. Manufacturing method. An insulating thin film obtained by the manufacturing method according to any one of 4.1 to 3 is used. It is a semiconductor element including the wiring structure described in 5.4.

The present invention will be described in detail below. First, the coating composition used in the present invention will be described.
The coating composition used in the present invention is characterized by containing (A) an inorganic component or an organic component. The inorganic component or the organic component (A) is not limited to inorganic or organic, and is cured and insulated by heat after coating, and is not particularly limited as long as it is soluble in a solvent.

Examples of such components include silica precursors of silicon oxide and organic silsesquioxane (including at least one or more of alkoxysilane and its hydrolyzate and polycondensed product), hydrogen silsesquioxy. Inorganic resin such as silica precursor of Sun resin, polyimide resin, fluorocarbon resin, benzocyclobutene resin, polyallyl ether resin, fluorinated polyallyl ether resin, cyclic perfluoro resin, polyquinoline resin, all Examples thereof include aromatic resins and oxazole resins. The resin may be one kind or a mixture of two or more kinds.

In order to provide more excellent electric insulation properties, resins such as silicon oxide, organic silsesquioxane and hydrogen silsesquioxane, which can be silica represented by the following formula after curing, are preferable. R _{x Hy} SiO _z (3) (R represents a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms or an aryl group, and 0 ≦ x <2, 0 ≦ y <2,
0 ≦ (x + y) <2, 1 <z ≦ 2).

The case where an inorganic resin is used as the component (A) will be described in more detail below. When the inorganic resin is used as the component (A) in the present invention, it is preferable to use the alkoxysilane represented by the general formulas (1) and (2) as a starting material. In the present invention, the alkoxysilane that is hydrolyzed and polycondensed to have a condensation rate of more than 90% is referred to as cured (or gelled) silica in the present invention. Therefore, the case where the silica precursor containing any one or more of the above-mentioned alkoxysilane and its hydrolyzate and polycondensate is used as the inorganic resin in the coating composition of the present invention will be described in detail below.

First, the silica precursor used in the present invention will be described. The alkoxysilane represented by the general formula (1) and its hydrolyzate and polycondensate contained in the silica precursor that can be used in the present invention have a starting material of alkoxysilane having 4, 3, 2 and 1 functions. It is of sex. Here, Si (OR ² ) _{4 is referred} to as a tetrafunctional alkoxysilane, and when n is 1 in the general formula (1),
That is, when R ¹ (Si) (OR ² ) ₃ is a trifunctional alkoxysilane and n is 2, that is, R ¹ ₂ (Si) (OR ² ) ₂ is a bifunctional alkoxysilane and n is 3. , That is, R ¹ ₃
(Si) (OR ² ) is a monofunctional alkoxysilane.

In the present invention, the alkoxysilane and its hydrolyzate and polycondensate are hereinafter referred to as alkoxysilane and the like. Specific examples of the tetrafunctional alkoxysilane among the alkoxysilanes represented by the general formula (1) include tetramethoxysilane, tetraethoxysilane, tetra (n-propoxy) silane, tetra (i-propoxy) silane, Tetra (n-butoxy) silane, tetra-
sec-butoxysilane, tetra-tert-butoxysilane, tetramethoxysilane, tetraethoxysilane,
Tetra-n-propoxysilane, tetra-iso-propoxysilane, tetra-n-butoxysilane, tetra-sec-
Examples include butoxysilane and tetra-tert-butoxysilane.

Specific examples of trifunctional alkoxysilanes among the alkoxysilanes represented by the general formula (1) include trimethoxysilane, triethoxysilane, methyltrimethoxysilane, methyltriethoxysilane and ethyltrimethoxysilane. , Ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane,
Isobutyltriethoxysilane, cyclohexyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, methyltri-n-propoxysilane, methyltri-iso -Propoxysilane, methyltri-n-butoxysilane, methyltri-sec-butoxysilane, methyltri-tert-butoxysilane, ethyltri-n-propoxysilane, ethyltri-iso-propoxysilane, ethyltri-n-butoxysilane, ethyltri
-sec-butoxysilane, ethyltri-tert-butoxysilane, n-propyltri-n-propoxysilane, n-
Propyltri-iso-propoxysilane, n-propyltri-n-butoxysilane, n-propyltri-sec-butoxysilane, n-propyltri-tert-butoxysilane, i-propyltrimethoxysilane, i-propyltriethoxy Silane, i-propyltri-n-propoxysilane, i-propyltri-iso-propoxysilane, i-
Propyltri-n-butoxysilane, i-propyltri-s
ec-butoxysilane, i-propyltri-tert-butoxysilane, n-butyltrimethoxysilane, n-butyltriethoxysilane, n-butyltri-n-propoxysilane, n-butyltri-iso-propoxysilane, n-butyltri -n-butoxysilane, n-butyltri-sec-
Butoxysilane, n-butyltri-tert-butoxysilane, n-butyltriphenoxysilane, sec-butyltrimethoxysilane, sec-butyl-tri-n-propoxysilane, sec-butyl-tri-iso-propoxysilane, sec- Butyl-tri-n-butoxysilane, sec-
Butyl-tri-sec-butoxysilane, sec-butyl-
Tri-tert-butoxysilane, t-butyltrimethoxysilane, t-butyltriethoxysilane, t-butyltri-n-propoxysilane, t-butyltri-iso-propoxysilane, t-butyltri-n-butoxysilane, t-
Butyltri-sec-butoxysilane, t-butyltri-t
Examples thereof include ert-butoxysilane, phenyltri-n-propoxysilane, phenyltri-iso-propoxysilane, phenyltri-n-butoxysilane, phenyltri-sec-butoxysilane and phenyltri-tert-butoxysilane.

A partial hydrolyzate of an alkoxysilane may be used as a raw material. Among these tetrafunctional and trifunctional alkoxysilanes, particularly preferable are tetramethoxysilane, tetraethoxysilane, trimethoxysilane,
Examples are triethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane.

Specific examples of the bifunctional alkoxysilane represented by the general formula (1) include dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldi (n-propoxy) silane, dimethyldi (i-propoxy) silane, Dimethyldi (n-butoxy) silane, dimethyldi (sec-butoxy) silane, dimethyldi (tert-butoxysilane), diethyldimethoxysilane, diethyldiethoxysilane, diethyldi (n-propoxy) silane, diethyldi (i-propoxy) silane, diethyldi (N-butoxy) silane, diethyldi (sec-butoxy) silane, diethyldi (tert-butoxysilane), diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldi (n-propoxy) silane,
Diphenyldi (i-propoxy) silane, diphenyldi (n-butoxy) silane, diphenyldi (sec-butoxy) silane, diphenyldi (tert-butoxysilane), methylethyldimethoxysilane, methylethyldiethoxysilane, methylethyldi (n -Propoxy) silane, methylethyldi (i-propoxy) silane, methylethyldi (n-butoxy) silane, methylethyldi (sec-butoxy) silane, methylethyldi (ter)
t-butoxysilane), methylpropyldimethoxysilane, methylpropyldiethoxysilane, methylpropidi (n-propoxy) silane, methylpropyldi (i-propoxy) silane, methylpropyldi (n-butoxy)
Silane, methylpropyldi (sec-butoxy) silane, methylpropyldi (tert-butoxysilane),
Methylphenyldimethoxysilane, methylphenyldiethoxysilane, methylphenyldi (n-propoxy) silane, methylphenyldi (i-propoxy) silane, methylphenyldi (n-butoxy) silane, methylphenyldi (sec-butoxy) silane , Methylfaildi (tert-butoxysilane), ethylphenyldimethoxysilane, ethylphenyldiethoxysilane, ethylphenyldi (n-propoxy) silane, ethylphenyldi (i-propoxy) silane, ethylphenyldi (n-
Examples thereof include butoxy) silane, ethylphenyldi (sec-butoxy) silane, ethylphenyldi (tert-butoxysilane), and other alkylsilanes in which two alkyl groups or aryl groups are bonded to the silicon atom.

Further, methylvinyldimethoxysilane, methylvinyldiethoxysilane, methylvinyldi (n-propoxy) silane, methylvinyldi (i-propoxy).
Silane, methylvinyldi (n-butoxy) silane, methylvinyldi (sec-butoxy) silane, methylvinyldi (tert-butoxysilane), divinyldimethoxysilane, divinyldiethoxysilane, divinyldi (n-
1 to 2 vinyl groups are bonded to a silicon atom such as propoxy) silane, divinyldi (i-propoxy) silane, divinyldi (n-butoxy) silane, divinyldi (sec-butoxy) silane, divinyldi (tert-butoxysilane). Alkylsilanes and the like are also suitable.

Specific examples of the monofunctional alkoxysilane represented by the general formula (1) include trimethylmethoxysilane, trimethylethoxysilane, trimethyl (n-propoxy) silane, trimethyl (i-propoxy) silane and trimethyl (n). -Butoxy) silane, trimethyl (sec-butoxy) silane, trimethyl (tert-butoxysilane), triethylmethoxysilane, triethylethoxysilane, triethyl (n-propoxy) silane, triethyl (i-propoxy) silane, triethyl (n-butoxy) ) Silane, triethyl (sec-butoxy) silane, triethyl (tert-butoxysilane), tripropylmethoxysilane, tripropylethoxysilane, tripropyl (n-propoxy) silane,
Tripropyl (i-propoxy) silane, tripropyl (n-butoxy) silane, tripropyl (sec-butoxy) silane, tripropyl (tert-butoxysilane), triphenylmethoxysilane, triphenylethoxysilane, triphenyl (n -Propoxy) silane,
Triphenyl (i-propoxy) silane, triphenyl (n-butoxy) silane, triphenyl (sec-butoxy) silane, triphenyl (tert-butoxysilane), methyldiethylmethoxysilane, methyldiethylethoxysilane, methyldiethyl (n -Propoxy) silane, methyldiethyl (i-propoxy) silane, methyldiethyl (n-butoxy) silane, methyldiethyl (sec-butoxy) silane, methyldiethyl (ter)
t-butoxysilane), methyldipropylmethoxysilane, methyldipropylethoxysilane, methyldipropyl (n-propoxy) silane, methyldipropyl (i-
Propoxy) silane, methyldipropyl (n-butoxy) silane, methyldipropyl (sec-butoxy) silane, methyldipropyl (tert-butoxysilane), methyldiphenylmethoxysilane, methyldiphenylethoxysilane, methyldiphenyl (n-propoxy) ) Silane, methyldiphenyl (i-propoxy) silane, methyldiphenyl (n-butoxy) silane, methyldiphenyl (sec-butoxy) silane, methyldiphenyl (tert-butoxysilane), ethyldimethylmethoxysilane, ethyldimethylethoxysilane, ethyl Dimethyl (n-propoxy) silane, ethyldimethyl (i-propoxy) silane, ethyldimethyl (n-butoxy) silane, ethyldimethyl (sec-butoxy) silane, ethyldimethyl (tert-) Tokishishiran),
Ethyldipropylmethoxysilane, ethyldipropylethoxysilane, ethyldipropyl (n-propoxy) silane, ethyldipropyl (i-propoxy) silane, ethyldipropyl (n-butoxy) silane, ethyldipropyl (sec-butoxy) Silane, ethyldipropyl (tert-butoxysilane), ethyldiphenylmethoxysilane, ethyldiphenylethoxysilane, ethyldiphenyl (n-propoxy) silane, ethyldiphenyl (i-propoxy) silane, ethyldiphenyl (n-
Butoxy) silane, ethyldiphenyl (sec-butoxy) silane, ethyldiphenyl (tert-butoxysilane), propyldimethylmethoxysilane, propyldimethylethoxysilane, propyldimethyl (n-propoxy) silane, propyldimethyl (i-propoxy) silane, Propyldimethyl (n-butoxy) silane, propyldimethyl (sec-butoxy) silane, propyldimethyl (tert-butoxysilane), propyldiethylmethoxysilane, propyldiethylethoxysilane,
Propyldiethyl (n-propoxy) silane, propyldiethyl (i-propoxy) silane, propyldiethyl (n-butoxy) silane, propyldiethyl (sec-
Butoxy) silane, propyldiethyl (tert-butoxysilane), propyldiphenylmethoxysilane, propyldiphenylethoxysilane, propyldiphenyl (n-propoxy) silane, propyldiphenyl (i-
Propoxy) silane, propyldiphenyl (n-butoxy) silane, propyldiphenyl (sec-butoxy)
Silane, propyldiphenyl (tert-butoxysilane) phenyldimethylmethoxysilane, phenyldimethylethoxysilane, phenyldimethyl (n-propoxy) silane, phenyldimethyl (i-propoxy) silane, phenyldimethyl (n-butoxy) silane, phenyldimethyl ( sec-butoxy) silane, phenyldimethyl (tert-butoxysilane), phenyldiethylmethoxysilane, phenyldiethylethoxysilane, phenyldiethyl (n-propoxy) silane, phenyldiethyl (i-propoxy) silane, phenyldiethyl (n-butoxy) Silane, phenyldiethyl (sec-
Butoxy) silane, phenyldiethyl (tert-butoxysilane), phenyldipropylmethoxysilane, phenyldipropylethoxysilane, phenyldipropyl (n-propoxy) silane, phenyldipropyl (i-
Propoxy) silane, phenyldipropyl (n-butoxy) silane, phenyldipropyl (sec-butoxy)
Examples thereof include silane and phenyldipropyl (tert-butoxysilane).

Alkylsilanes having 1 to 3 vinyl groups bonded to silicon atoms are also suitable. Specifically, trivinylmethoxysilane, trivinylethoxysilane, trivinyl (n-propoxy) silane, trivinyl (i-propoxy) silane, trivinyl (n-butoxy) silane, trivinyl (sec-butoxy) silane,
Trivinyl (tert-butoxysilane), vinyldimethylmethoxysilane, vinyldimethylethoxysilane,
Vinyldimethyl (n-propoxy) silane, vinyldimethyl (i-propoxy) silane, vinyldimethyl (n-)
Butoxy) silane, vinyldimethyl (sec-butoxy) silane, vinyldimethyl (tert-butoxysilane), vinyldiethylmethoxysilane, vinyldiethylethoxysilane, vinyldiethyl (n-propoxy) silane, vinyldiethyl (i-propoxy) silane, Vinyldiethyl (n-butoxy) silane, vinyldiethyl (sec-butoxy) silane, vinyldiethyl (ter)
t-butoxysilane), vinyldipropylmethoxysilane, vinyldipropylethoxysilane, vinyldipropyl (n-propoxy) silane, vinyldipropyl (i-
Propoxy) silane, vinyldipropyl (n-butoxy) silane, vinyldipropyl (sec-butoxy) silane, vinyldipropyl (tert-butoxysilane)
And so on.

As the monofunctional and difunctional alkoxysilanes of the present invention, the above-mentioned alkoxysilanes are used. Among them, more preferred are trimethylmethoxysilane, trimethylethoxysilane, triethylmethoxysilane, Such as triethylethoxysilane, tripropylmethoxysilane, tripropylmethoxysilane, tripropylethoxysilane, triphenylmethoxysilane, triphenylethoxysilane, phenyldimethylmethoxysilane, phenyldimethylethoxysilane, diphenylmethylmethoxysilane, diphenylmethylethoxysilane, etc. Alkylsilane, dimethyldiethoxysilane, dimethyldiethoxysilane, diethyldiethoxysilane, diphenyldiethoxysilane, methylethyldiethoxysilane , Methylphenyl diethoxy silane, ethyl phenyl diethoxy silane, dimethyl dimethoxy silane, dimethyl dimethoxy silane, diethyl dimethoxy silane, diphenyl dimethoxy silane, methyl ethyl dimethoxy silane, methyl phenyl dimethoxy silane, and that such ethylphenyl dimethoxysilane.

Further, a hydrogen atom is directly bonded to a silicon atom such as methyldimethoxysilane, methyldiethoxysilane, ethyldimethoxysilane, ethyldiethoxysilane, propyldimethoxysilane, propyldiethoxysilane, phenyldimethoxysilane and phenyldiethoxysilane. It is also possible to use the prepared one. The alkoxysilane represented by the general formula (2) that can be used in the present invention has an alkoxysilane of 6 as a starting material,
It is 5, 4, 3 and bifunctional.

Alkoxysilane represented by the general formula (2)
, For example, m = q = 1 and R ³(R^FourO)₂Si-
(R⁷)_p-Si (OR^Five)₂R⁶The compound of
Coxisilane, m = 0, q = 1 or m = 1, q = 0
Then, (R^FourO)₃Si- (R⁷)_p-Si (OR^Five)₂R⁶Of
The compound is a pentafunctional alkoxysilane with m = q = 0 (R
^FourO)₃Si- (R⁷)_p-Si (OR^Five)₃6-functional compound
Of the general formula (2), m = q =
2 or R³ ₂(R^FourO) Si- (R⁷)_p-Si (O
R^Five) R⁶ ₂Is a bifunctional alkoxysilane, m = 2, q =
1 or m = 1, q = 2, R³ ₂(R^FourO) Si-
(R⁷)_p-Si (OR^Five)₂R⁶ The compound of
Lucoxysilane.

Among the alkoxysilanes represented by the general formula (2), compounds in which R ⁷ is-(CH ₂ ) n-- are 6, 4, and 2
Specific examples of the functional alkoxysilane include bis (trimethoxysilyl) as an example of the hexafunctional alkoxysilane.
Methane, bis (triethoxysilyl) methane, bis (triphenoxysilyl) methane, bis (trimethoxysilyl) ethane, bis (triethoxysilyl) ethane, bis (triphenoxysilyl) ethane, 1,3-bis (trimethoxy) Silyl) propane, 1,3-bis (triethoxysilyl) propane, 1,3-bis (triphenoxysilyl) propane, 1,4-bis (trimethoxysilyl)
Benzene, 1,4-bis (triethoxysilyl) benzene. Examples of tetrafunctional alkoxysilanes are bis (dimethoxymethylsilyl) methane, bis (diethoxymethylsilyl) methane, bis (dimethoxyphenylsilyl) methane, bis (diethoxyphenylsilyl) methane, bis (dimethoxymethylsilyl) ethane. , Bis (diethoxymethylsilyl) ethane, bis (dimethoxyphenylsilyl) ethane, bis (diethoxyphenylsilyl) ethane, 1,3-bis (dimethoxymethylsilyl) propane, 1,3-bis (diethoxymethylsilyl) Examples include propane, 1,3-bis (dimethoxyphenylsilyl) propane, 1,3-bis (diethoxyphenylsilyl) propane and the like. Specific examples of the bifunctional alkoxysilane include bis (methoxydimethylsilyl) methane,
Bis (ethoxydimethylsilyl) methane, bis (methoxydiphenylsilyl) methane, bis (ethoxydiphenylsilyl) methane, bis (methoxydimethylsilyl) ethane, bis (ethoxydimethylsilyl) ethane, bis (methoxydiphenylsilyl) ethane, bis ( Ethoxydiphenylsilyl) ethane, 1,3-bis (methoxydimethylsilyl) propane, 1,3-bis (ethoxydimethylsilyl) propane, 1,3-bis (methoxydiphenylsilyl) propane, 1,3-bis (ethoxydiphenyl) Silyl) propane and the like.

As the compound of the general formula (2) in which R ⁷ is an oxygen atom, hexamethoxydisiloxane, hexaethoxydisiloxane, hexaphenoxydisiloxane, 1,
1,1,3,3-pentamethoxy-3-methyldisiloxane, 1,1,1,3,3-pentaethoxy-3-methyldisiloxane, 1,1,1,3,3-pentamethoxy-3 -
Phenyldisiloxane, 1,1,1,3,3-pentaethoxy-3-phenyldisiloxane, 1,1,3,3-tetramethoxy-1,3-dimethyldisiloxane, 1,
1,3,3-Tetraethoxy-1,3-dimethyldisiloxane, 1,1,3,3-tetramethoxy-1,3-diphenyldisiloxane, 1,1,3,3-tetraethoxy-
1,3-diphenyldisiloxane, 1,1,3-trimethoxy-1,3,3-trimethyldisiloxane, 1,
1,3-triethoxy-1,3,3-trimethyldisiloxane, 1,1,3-trimethoxy-1,3,3-triphenyldisiloxane, 1,1,3-triethoxy-1,
3,3-triphenyldisiloxane, 1,3-dimethoxy-1,1,3,3-tetramethyldisiloxane, 1,
3-diethoxy-1,1,3,3-tetramethyldisiloxane, 1,3-dimethoxy-1,1,3,3-tetraphenyldisiloxane, 1,3-diethoxy-1,1,3,
Examples thereof include 3-tetraphenyldisiloxane. Bifunctional compounds include 3-dimethoxy-
1,1,3,3-tetramethyldisiloxane, 1,3-diethoxy-1,1,3,3-tetramethyldisiloxane,
Examples thereof include 1,3-dimethoxy-1,1,3,3-tetraphenyldisiloxane and 1,3-diethoxy-1,1,3,3-tetraphenyldisiloxane.

A compound of the general formula (2) in which p is 0 is 6,
Specific examples of 5-, 4-, 3- and 2-functional alkoxysilanes include 6-functional alkoxysilanes such as hexamethoxydisilane, hexaethoxydisilane, hexaphenoxydisilane and 5-functional alkoxysilanes. 1,1,1,2,2-pentamethoxy-2-
Methyldisilane, 1,1,1,2,2-pentaethoxy-
Specific examples of 2-methyldisilane, 1,1,1,2,2-pentamethoxy-2-phenyldisilane, 1,1,1,2,2-pentaethoxy-2-phenyldisilane and tetrafunctional alkoxysilane As 1,1,2,2-tetramethoxy
-1,2-dimethyldisilane, 1,1,2,2-tetraethoxy-1,2-dimethyldisilane, 1,1,2,2-tetramethoxy-1,2-diphenyldisilane, 1,1,
2,2-tetraethoxy-1,2-diphenyldisilane,
Specific examples of trifunctional alkoxysilanes are 1,1,2
-Trimethoxy-1,2,2-trimethyldisilane, 1,
1,2-triethoxy-1,2,2-trimethyldisilane, 1,1,2-trimethoxy-1,2,2-triphenyldisilane, 1,1,2-triethoxy-1,2,2-triphenyldisilane Specific examples of the bifunctional alkoxysilane include 1,2-dimethoxy-1,1,2,2-tetramethyldisilane and 1,2-diethoxy-1,1,2,2-
Tetramethyldisilane, 1,2-dimethoxy-1,1,
2,2-tetraphenyldisilane, 1,2-diethoxy-
Examples include 1,1,2,2-tetraphenyldisilane.

Of the alkoxysilanes represented by the above general formula (2), it is preferable to use a pentafunctional or trifunctional alkoxysilane. The silica precursor of the present invention is characterized by containing at least one or more of the above alkoxysilanes and their hydrolyzed and polycondensed products, and the hydrolyzate also includes a partial hydrolyzate. . For example, in the case of a tetrafunctional alkoxysilane used as a silica precursor, it is not necessary that all four alkoxys be hydrolyzed, for example, only one is hydrolyzed, two or more are hydrolyzed. It is also possible that the above-mentioned substances or a mixture thereof are present. Further, the polycondensate contained in the silica precursor in the present invention is one in which the silanol groups of the hydrolyzate of the silica precursor are condensed to form a Si-O-Si bond,
It is not necessary that all of the silanol groups are condensed, and it means that some of the silanol groups are condensed, a mixture of those having different degrees of condensation, and the like.

The above-mentioned alkoxysilanes are used as the mono-, di-, and tri-functional alkoxysilanes of the present invention. Among them, more preferred are trimethylethoxysilane, triethylethoxysilane, and tripropylethoxy. Alkylsilane, such as silane, triphenylethoxysilane, phenyldimethylethoxysilane, and diphenylmethylethoxysilane, in which three alkyl groups or aryl groups are directly bonded to silicon atoms, dimethyldiethoxysilane, dimethyldiethoxysilane, and diethyldiethoxysilane. , Diphenyldiethoxysilane, methylethyldiethoxysilane, methylphenyldiethoxysilane, ethylphenyldiethoxysilane, and other alkylsilanes in which two alkyl groups or aryl groups are directly bonded to a silicon atom, Luo, directly to a silicon atom described above 1
Alkoxysilanes to which one alkyl group or aryl group is bonded are included.

It is also possible to use those in which a hydrogen atom is directly bonded to a silicon atom, such as methyldiethoxysilane, dimethylvinylmethoxysilane and dimethylvinylethoxysilane. Furthermore, bis (ethoxydimethylsilyl) methane, bis (ethoxydiphenylsilyl) methane, bis (ethoxydimethylsilyl) ethane, bis (ethoxydiphenylsilyl) ethane, 1,3-bis (ethoxydimethylsilyl) propane, 1,3- Bis (ethoxydiphenylsilyl) propane, 3-diethoxy-1,
1,3,3-tetramethyldisiloxane, 1,3-diethoxy-1,1,3,3-tetraphenyldisiloxane,
1,2-diethoxy-1,1,2,2-tetramethyldisilane, 1,2-diethoxy-1,1,2,2-tetraphenyldisilane and the like can be preferably used. The content of the silica precursor in the coating composition of the present invention can be expressed as a solid content concentration. As will be described later, the solid content concentration is preferably 2 to 30% by weight, depending on the thickness of the target insulating thin film, and the storage stability is also excellent.

Next, the component (B) in the present invention will be described. The component (B) volatilizes or generates a gas by heat during or after the component (A) is cured, and preferably volatilizes out of the system to form pores in the insulating thin film, and the insulating film Is a component that acts to lower the relative dielectric constant of. The temperature at which the component (B) volatilizes or generates a gas is in the range of 0 to 500 ° C, preferably 25 to 400 ° C under atmospheric pressure.

Above all, the component (B) which can be preferably used in the present invention has a low thermal decomposition temperature when the coating film is converted into a porous thin film by heating and baking as described later and has a silica precursor and silica. Is a linear or branched block copolymer of two or more elements, which has a reasonably good compatibility with
The block portion is an organic polymer having repeating units of linear and cyclic oxyalkylene groups having 1 to 8 carbon atoms, and the block copolymer unit contains 60% by weight or more in one polymer chain.

Here, the reason that the compatibility is reasonably good is that
The block copolymer used in the present invention has good affinity with the silica precursor and silica. A moderately good affinity between them controls the phase separation state between the silica precursor and the polymer, and is extremely extreme when the block copolymer is extracted from silica in the subsequent step to form a porous body. Since there are no pores having large or small pore diameters and the pore diameters are uniform, the surface smoothness of the obtained thin film is further improved and the mechanical strength is also high.

Specific block copolymers include polyethylene glycol polypropylene glycol, polyethylene glycol polybutylene glycol, and the like 2.
Mention may be made of original block copolymers as well as polyether block copolymers such as linear ternary block copolymers such as polyethylene glycol polypropylene glycol polyethylene glycol, polypropylene glycol polyethylene glycol polypropylene glycol, polyethylene glycol polybutylene glycol polyethylene glycol.

Further, as the branched block copolymer, at least three of the hydroxyl groups contained in the sugar chain represented by glycerol, erythritol, pentaerythritol, pentitol, pentose, hexitol, hexose, heptose and the like and the polymer chain are included. The bonded structure and / or the structure in which at least three of the hydroxyl group and the carboxyl group contained in the hydroxyl acid are bonded to the block copolymer chain are included. Specifically, glycerol polyethylene glycol polypropylene glycol, erythritol polyethylene glycol polypropylene glycol polyethylene glycol and the like are included.

Specific examples of sugar chains that can be used other than the sugar chains used to obtain the above block copolymer on branch include sorbitol, mannitol,
Xylitol, threitol, maltitol, arabitol, lactitol, adonitol, cellobitol, glucose, fructose, sucrose, lactose, mannose, galactose, erythrose, xylulose, allulose, ribose, sorbose, xylose,
Examples include arabinose, isomaltose, dextrose, glucoheptose and the like. Further, specific examples of the hydroxyl acid, citric acid, malic acid, tartaric acid, gluconic acid, glucuronic acid, glucoheptonic acid, glucooctanoic acid, threonic acid, saccharic acid, galactonic acid, galactaric acid, galacturonic acid, glyceric acid, Examples thereof include hydroxysuccinic acid.

Further, in the present invention, a block copolymer obtained by addition-polymerizing an alkylene oxide with an aliphatic higher alcohol can also be used. Specifically, polyoxyethylene lauryl ether, polyoxypropylene lauryl ether, polyoxyethylene oleyl ether, polyoxypropylene oleyl ether, polyoxyethylene cetyl ether, polyoxypropylene cetyl ether, polyoxyethylene stearyl ether, polyoxypropylene stearyl. Examples include ether. The terminal group of the block copolymer is not particularly limited, but includes a hydroxyl group, a linear and cyclic alkyl ether group, an alkyl ester group, an alkylamide group,
It is preferably a group modified with an alkyl carbonate group, a urethane group or a trialkylsilyl group.

In the present invention, an aliphatic polyether, an aliphatic polyester, in which the main chain structure of the polymer disappears by heating and calcination and is easily converted into a porous silicon oxide,
It is also preferable to use an organic polymer which is a polymer mainly composed of an aliphatic polycarbonate or an aliphatic polyanhydride and in which at least one of the polymer end groups has a group chemically inactive to the silica precursor. Is. Suitable polymer end groups have 1 to 8 carbon atoms.
Examples thereof include linear, branched, and cyclic alkyl ether groups, alkyl ester groups, alkyl amide groups, and alkyl carbonate groups.

The above polymers may be used alone or as a mixture of a plurality of polymers. The main chain of the polymer is
A polymer chain having any repeating unit other than the above may be contained within a range not impairing the effects of the present invention. Further, since the end group of the present invention has particularly good compatibility with the silica precursor, a branched polymer is preferable as the polymer form because it can have more end groups in the molecule. In such a case, the branched portion is glycerol, erythritol, erythrose, pentaerythritol, pentitol, pentose, hexitol,
A structure in which at least three of hydroxyl groups contained in a sugar chain represented by hexose, heptose and the like are bonded to an organic polymer chain, and / or at least three of hydroxyl groups and carboxyl groups contained in a hydroxyl acid and an organic polymer chain It is preferable that the structure has a bond.

As examples of the aliphatic polyether of the present invention,
The main chain is an alkylene glycol such as polyethylene glycol, polypropylene glycol, polyisobutylene glycol, polytrimethylene glycol, polytetramethylene glycol, polypentamethylene glycol, polyhexamethylene glycol, polydioxolane, and polydioxepane, and at least one end thereof is Alkyl ether, alkyl ester, alkyl amide,
Examples thereof include those that have been alkylcarbonated. The group of ether, ester, amide, and carbonate may be directly chemically bonded to the repeating unit at the polymer terminal, or may be bonded via an organic group.

Examples of the etherified end groups of the aliphatic polyether include those in which at least one end of the above alkylene glycol is etherified with, for example, methyl ether, ethyl ether, propyl ether, glycidyl ether, and the like. Specifically, for example, polyethylene glycol monomethyl ether, polyethylene glycol dimethyl ether, polypropylene glycol dimethyl ether, polyisobutylene glycol dimethyl ether, polyethylene glycol diethyl ether, polyethylene glycol monoethyl ether, polyethylene glycol dibutyl ether, polyethylene glycol monobutyl ether, polyethylene glycol diglycidyl ether. , Polyethylene polypropylene glycol dimethyl ether Ether, glycerin polyethylene glycol trimethyl ether, pentaerythritol polyethylene grayed reel tetramethyl ether, pentitol polyethylene glycol pentamethyl ether, sorbitol polyethylene glycol hexamethyl ether is particularly preferably used.

As the aliphatic polyethers having an ester group at the terminal, at least one terminal of the above alkylene glycols is, for example, acetic acid ester, propionic acid ester, acrylic acid ester, methacrylic acid ester,
Examples include benzoic acid esters. Also,
It is also preferable to use an alkylene glycol in which the terminal is converted to carboxymethyl ether and the terminal carboxyl group is converted to alkyl ester. Specifically, for example,
Polyethylene glycol monoacetate, polyethylene glycol diacetate, polypropylene glycol monoacetate, polypropylene glycol diacetate, polyethylene glycol dibenzoate, polyethylene glycol diacrylate, polyethylene glycol monomethacrylate, polyethylene glycol dimethacrylate Ester, polyethylene glycol biscarboxymethyl ether dimethyl ester, polypropylene glycol biscarboxymethyl ether dimethyl ester, glycerin polyethylene glycol triacetic acid ester, pentaerythritol polyethylene glycol tetraacetic acid ester, pentitol polyethylene glycol pentaacetic acid ester, sorbitol polyethylene Such as glycol hexa acetate are preferred examples.

As the aliphatic polyethers having an amide group at the terminal, at least one terminal of the above alkylene glycols is converted to carboxymethyl ether and then amidated, or after the hydroxy terminal is modified with an amino group. Examples of the amidation method include polyethylene glycol bis (carboxymethyl ether dimethylamide), polypropylene glycol bis (carboxymethyl ether dimethylamide), polyethylene glycol bis (carboxymethyl ether diethylamide), glycerin polyethylene glycol. Tricarboxymethyl ether dimethylamide, pentaerythritol polyethylene glycol Tetracarboxymethyl ether dimethylamide, pentitol polyethylene glycol Printer carboxymethyl ether dimethylamide, sorbitol polyethylene glycol hexa carboxymethyl ether dimethylamide is preferably used.

Examples of the aliphatic polyethers having an alkyl carbonate group at the end include a method of attaching a formyl ester group to at least one end of the above alkylene glycols, and specifically, bismethoxycarbonyloxy polyethylene. Examples thereof include glycol, bisethoxycarbonyloxy polyethylene glycol, bisethoxycarbonyloxy polypropylene glycol, bis-tert-butoxycarbonyloxy polyethylene glycol and the like.

Further, aliphatic polyethers modified with a urethane group or a trialkylsilyl group at the terminal can also be used. In the trialkylsilyl modification, trimethylsilyl modification is particularly preferable, and it can be modified with trimethylchlorosilane, trimethylchlorosilylacetamide or hexamethyldisilazane.

Examples of aliphatic polyesters include polycondensates of hydroxycarboxylic acids such as polyglycolide, polycaprolactone and polypivalolactone, and ring-opening polymers of lactones, and polyethylene oxalate, polyethylene succinate, polyethylene adipate. A polycondensation product of a dicarboxylic acid such as polyethylene sebacate, polypropylene adipate, and polyoxydiethylene adipate with an alkylene glycol, and a ring-opening copolymerization product of an epoxide and an acid anhydride, wherein at least one terminal of the polymer is Examples thereof include those modified with an alkyl ether group, an alkyl ester group, an alkylamide group, an alkyl carbonate group, a urethane group, or a trialkylsilyl group.

Examples of the aliphatic polycarbonate include polycarbonates such as polyethylene carbonate, polypropylene carbonate, polypentamethylene carbonate, polyhexamethylene carbonate as the main chain portion, and at least one terminal of the polymer has an alkyl ether group. , Those modified with an alkyl ester group, an alkyl amide group, an alkyl carbonate group, a urethane group, and a trialkylsilyl group.

Examples of the aliphatic polyanhydride include dicarboxylic acids such as polymalonyl oxide, polyadipoyl oxide, polypimeloyl oxide, polysuberoyl oxide, polyazela oil oxide and polysebacyl oxide as the main chain portion. The polycondensate of the polymer may be mentioned, and at least one end of the polymer modified with an alkyl ether group, an alkyl ester group, an alkylamide group, an alkyl carbonate group, a urethane group or a trialkylsilyl group. You can

Further, in the present invention, an organic polymer having at least one polymerizable functional group in the molecule can also be used. The use of such a polymer improves the strength of the porous thin film, although the reason is not clear. As the polymerizable functional group, vinyl group, vinylidene group, vinylene group, glycidyl group, allyl group, acrylate group, methacrylate group, acrylamide group, methacrylamide group,
Carboxyl group, hydroxyl group, isocyanate group,
Examples thereof include an amino group, an imino group and a halogen group. These functional groups can be in the main chain of the polymer, at the ends or at the side chains. Further, it may be directly bonded to the polymer chain or may be bonded via a spacer such as an alkylene group or an ether group. The same polymer molecule may have one type of functional group or two or more types of functional groups. Among the functional groups listed above, vinyl group, vinylidene group, vinylene group, glycidyl group, allyl group, acrylate group, methacrylate group, acrylamide group, and methacrylamide group are preferably used.

As the basic skeleton of this polymer, as in the above-mentioned examples of the polymer, one having an aliphatic polyether, an aliphatic polyester, an aliphatic polycarbonate and an aliphatic polyanhydride having a low thermal decomposition temperature as main constituent components is used. It is particularly preferable to use. The basic skeleton of the organic polymer having a polymerizable functional group that can be used in the present invention will be described more specifically.

In the following, alkylene means methylene, ethylene, propylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, isopropylidene,
1,2-dimethylethylene and 2,2-dimethyltrimethylene, wherein alkyl includes C1 to C8 alkyl groups and aryl groups such as phenyl, tolyl, and anisyl groups, and (meth) acrylate Refers to both acrylate and methacrylate, and dicarboxylic acid refers to organic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid.

(A) Polyalkylene glycol (meth)
Acrylate, polyalkylene glycol di (meth) acrylate, polyalkylene glycol alkyl ether (meth) acrylate, polyalkylene glycol vinyl ether, polyalkylene glycol divinyl ether, polyalkylene glycol alkyl ether vinyl ether, polyalkylene glycol glycidyl ether, polyalkylene glycol diglycidyl An aliphatic polyether having a polymerizable functional group such as an acrylate group, a methacrylate group, a vinyl group and a glycidyl group at the end, which is represented by ether, polyalkylene glycol alkyl ether glycidyl ether and the like.

(B) Polycaprolactone (meth) acrylate, polycaprolactone vinyl ether, polycaprolactone glycidyl ether, polycaprolactone vinyl ester, polycaprolactone glycidyl ester, polycaprolactone vinyl ester (meth) acrylate, polycaprolactone glycidyl ester (meth) acrylate, Polycaprolactone vinyl ester vinyl ether, polycaprolactone glycidyl ester vinyl ether, polycaprolactone vinyl ester glycidyl ether, polycaprolactone glycidyl ester glycidyl ether, etc., acrylate group, methacrylate group at one or both ends,
Polycaprolactone having a polymerizable functional group such as a vinyl group or a glycidyl group.

(C) Polycaprolactone triol (meth) acrylate, di (meth) acrylate, tri (meth) acrylate, vinyl ether, divinyl ether, trivinyl ether, glycidyl ether, diglycidyl ether, triglycidyl ether. (D) An aliphatic polyester which is a polymer of dicarboxylic acid and alkylene glycol and has a polymerizable functional group such as an acrylate group, a methacrylate group, a vinyl group or a glycidyl group at one or both ends. (E) An aliphatic polyalkylene carbonate having a polymerizable functional group such as an acrylate group, a methacrylate group, a vinyl group or a glycidyl group at one end or both ends.

(F) An aliphatic polyanhydride which is a polymer of a dicarboxylic acid anhydride and has a polymerizable functional group such as an acrylate group, a methacrylate group, a vinyl group and a glycidyl group at the terminal. (G) Polyglycidyl (meth) acrylate, polyallyl (meth) acrylate, polyvinyl (meth) acrylate and the like, polyacrylic acid ester and polymethacrylic acid ester having a functional group such as vinyl group, glycidyl group and allyl group in the side chain. (H) Polymers such as polyvinyl cinnamate, polyvinyl azidobenzal, and epoxy resin can be used. In the present invention, a polymerizable organic monomer may be used as a starting material instead of the polymer. At this time, when the organic monomer contains a bifunctional organic monomer, the organic polymer in the obtained composite has a three-dimensional network and / or a graft structure.

Acrylic acid such as acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, ethylene bisacrylate, ethylene bismethacrylate, α-cyanoacrylic acid, α-cyanoacrylic acid ester and the like can be preferably used. Acid vinyl esters such as methacrylic acid derivatives, vinyl acetate, vinyl propionate, vinyl crotonic acid, vinyl benzoate, vinyl chloroformate, acrylamide, methacrylamide, N, N-dialkylacrylamide, N, N-dialkylmethacrylamide, N Amides such as -alkylacrylamide, N-alkylmethacrylamide, N, N'-methylenebisacrylamide, N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide, styrene, α-methyl Rustyrene, p-methoxystyrene, diphenylethylene, vinylnaphthalene, vinylanthracene, vinylcyclopentane, vinylcyclohexane, vinyl group-containing hydrocarbons such as 5-vinyl-2-norbornene, acrylonitrile derivatives such as acrylonitrile and methacrylonitrile, N -Vinyl amines such as -vinyl pyridine, N-vinyl carbazole and N-vinyl imidazole, vinyl alkyl ethers, vinyl alkyl ketones, glycidyl acrylate, glycidyl methacrylate, epoxy resins and the like.

These organic polymers and polymerizable organic monomers may be used alone or in combination of two or more kinds. Of course, it is also possible to use an organic polymer and a polymerizable organic monomer together. The organic polymer that can be used in the present invention has been described above. The number average molecular weight of the organic polymer is 100 to 1,000,000, preferably 100.
˜300,000, more preferably 200 to 50,000. When the molecular weight is 100 or less, the organic polymer is removed from the silica / organic polymer composite too quickly to obtain a porous silica thin film having a desired porosity,
When the polymer molecular weight exceeds 1,000,000, the removal rate of the polymer is too slow and the polymer remains, which is not preferable. In particular, a more preferable polymer has a molecular weight of 200 to 50,000, and in this case, a porous silica thin film having a desired high porosity can be obtained very easily at low temperature in a short time. What should be noted here is
The pore size of the porous silica is extremely small and uniform without depending on the molecular weight of the polymer.

The molecular weight of each block of the block copolymer used in the present invention is 100 to 100,000, preferably 100 to 100.
It is 50,000, more preferably 200 to 20,000. Molecular weight is 1
When it is 00 or less or 100,000 or more, an appropriate compatibility is not obtained between the silica precursor and the polymer, so that the mechanical strength of the porous silica thin film is not expressed.

The amount of the organic polymer added in the present invention is
Siloxane 1 obtained by assuming that the total amount of the starting material alkoxysilane charged has undergone hydrolysis and condensation reactions
0.01 to 10 parts by weight, preferably 0.0
It is 5 to 5 parts by weight, more preferably 0.5 to 3 parts by weight. If the addition amount of the organic polymer is less than 0.01 part by weight, a porous body having sufficient pores cannot be obtained, and even if it is more than 10 parts by weight, porous silica having sufficient mechanical strength cannot be obtained, Practicality is poor. The siloxane obtained by assuming that the total amount of the charged alkoxysilane has undergone hydrolysis and condensation reactions is SiOR of the general formulas (1) and (2).
^Two , SiOR ^{4 and} SiOR ⁵ groups are 100% hydrolyzed to SiOH and further 100% condensed to have a siloxane structure.

Next, the organic solvent (C) that can be used in the coating composition of the present invention will be described. The component (A) is not particularly limited as long as it can be dissolved, but among them, alcohol solvents, ketone solvents, amide solvents and ester solvents are preferable. Here, examples of the alcohol solvent include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, and 2-methyl. Butanol, sec
-Pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, se
c-hexanol, 2-ethylbutanol, sec-heptanol, heptanol-3, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, 2,6-dimethylheptanol-4, n-decanol, sec- Undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, s
ec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-
Trimethylcyclohexanol, benzyl alcohol,
Monoalcohol solvents such as diacetone alcohol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, pentanediol-
2,4,2-methylpentanediol-2,4, hexanediol-2,5, heptanediol-2,4,2-ethylhexanediol-1,3, diethylene glycol,
Polyhydric alcohol solvents such as dipropylene glycol, triethylene glycol, tripropylene glycol,
And ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol Monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene Examples thereof include polyhydric alcohol partial ether solvents such as glycol monomethyl ether, dipropylene glycol monoethyl ether and dipropylene glycol monopropyl ether. These alcohol solvents may be used either individually or in combination of two or more.

Of these alcohols, n-propanol, i-propanol, n-butanol, i-butanol
, Sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, sec
-Pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, s
ec-Hexanol, 2-ethylbutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether and the like are preferable. Ketone solvents include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl
-n-butyl ketone, diethyl ketone, methyl-i-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-i-butyl ketone, trimethylnonanone, cyclohexanone, 2-
Hexanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, acetophenone, fenchon, etc., as well as acetylacetone, 2,4-hexanedione, 2,4-heptanedione, 3,5-heptanedione, 2,4 -Octanedione, 3,5-octanedione, 2,4-nonanedione, 3,5-nonanedione,
5-methyl-2,4-hexanedione, 2,2,6,6-
Tetramethyl-3,5-heptanedione, 1,1,1,
Examples include β-diketones such as 5,5,5-hexafluoro-2,4-heptanedione. These ketone solvents may be used either individually or in combination of two or more.

As the amide solvent, formamide, N
-Methylformamide, N, N-dimethylformami
De, N-ethylformamide, N, N-diethylform
Amide, acetamide, N-methylacetamide, N,
N-dimethylacetamide, N-ethylacetamide,
N, N-diethylacetamide, N-methylpropionamide, N-methylpyrrolidone, N-formylmorpholine,
N-formylpiperidine, N-formylpyrrolidine, N-
Acetylmorpholine, N-acetylpiperidine, N-acetylpyrrolidine and the like can be mentioned. These amide solvents may be used either individually or in combination of two or more.

Ester solvents include diethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-
Valerolactone, n-propyl acetate, i-propyl acetate,
N-butyl acetate, i-butyl acetate, sec-butyl acetate,
N-Pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, n-nonyl acetate, methyl acetoacetate, acetoacetate Ethyl acetate, 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 glycol monoethyl ether acetate,
Propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, glycol diacetate,
Methoxytriglycol acetate, ethyl propionate, n-butyl propionate, i-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, malon Examples thereof include diethyl acid, dimethyl phthalate, and diethyl phthalate. These ester solvents may be used either individually or in combination of two or more.

It is preferable to use an alcohol solvent and / or an ester solvent as the solvent (C) in that a composition having good coatability and storage stability can be obtained. The coating composition of the present invention contains the above solvent (C), but a similar solvent can be additionally added when the silica precursor used as the component (A) is hydrolyzed and / or condensed.

In the present invention, an acid may be added to the coating composition. Specific examples of the acid that can be used in the present invention include:
Hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, tripolyphosphoric acid,
Inorganic acids such as phosphinic acid and phosphonic acid can be mentioned. Examples of organic acids include acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, and heptane.
Acid, octanoic acid, nonanoic acid, decanoic acid, oxalic acid, maleic acid, methylmalonic acid, adipic acid, sebacic acid, gallic acid, butyric acid, meritic acid, arachidonic acid, shikimic 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, succinic acid, iso Nicotinic acid etc. can be mentioned.

Further, a compound which functions as an acid after the coating solution of the present invention is coated on a substrate is also included. Specific examples thereof include compounds such as aromatic sulfonic acid esters and carboxylic acid esters that decompose by heating or light to generate an acid. The acid may be used alone or in combination of two or more kinds. The addition amount of these acid components is 1 mol or less, preferably 1 mol or less, based on 1 mol of the total number of mols of SiOR ² groups, SiOR ⁴ groups, and SiOR ⁵ groups of the alkoxysilanes of the general formulas (1) and / or (2) charged as starting materials. Is suitably 0.1 mol or less. If it is more than 1 mol, a precipitate may be generated, and it may be difficult to obtain a coating film made of a homogeneous porous silicon oxide.

In addition, if desired, for example, components such as colloidal silica and ionic and nonionic surfactants may be added, and a photocatalyst generator for imparting photosensitivity and a substrate may be added. It is also possible to add optional additives such as an adhesion improver for enhancing the adhesion and a stabilizer for long-term storage to the coating composition of the present invention within a range not impairing the gist of the present invention.

Next, a method for producing the coating composition of the present invention will be described. The coating composition of the present invention can be obtained by mixing the above-mentioned alkoxysilane, an organic polymer and a solvent. At least a part of the alkoxysilane is hydrolyzed and polycondensed so that the hydrolyzate of the alkoxysilane is an oligomer. It is desirable that they are condensed into a shape.

When the composition is hydrolyzed and polycondensed, the viscosity of the coating composition is appropriately increased, so that the shape retention of the coating film can be ensured and the film thickness can be made uniform. In this case, since the silica skeleton is mildly formed, the film shrinkage is less likely to occur.
Therefore, the alkoxysilane is treated under the following constant conditions. It should be noted that the treatment of the alkoxysilane may be carried out after mixing the alkoxysilane and the organic polymer, but it is also possible to pretreat the alkoxysilane and then mix the organic polymer.

In the present invention, the treatment conditions of alkoxysilane are usually 0 to 150 in the presence of water necessary for hydrolysis.
℃, preferably 0 to 100 ℃, more preferably 0 ℃ to 5
It may be processed at 0 ° C. When the temperature is lower than 0 ° C, the progress of hydrolysis is not sufficient, and when the temperature is higher than 150 ° C, the reaction rapidly proceeds excessively and gelation of the solution may occur, which is not preferable. As mentioned above, hydrolysis also includes partial hydrolysis. For example, in the case of a tetrafunctional alkoxysilane, it is not necessary for all four alkoxy groups to be hydrolyzed, for example, only one is hydrolyzed, two or more are hydrolyzed, Alternatively, a mixture of these may be present. Polycondensation is a condensation of silanol groups obtained by hydrolysis of alkoxysilane to form Si-O-Si bonds, but it is not necessary that all silanol groups are condensed, It does not matter even if the silanol groups are condensed,
The degree of condensation is represented by the condensation rate.

The condensation rate of the alkoxysilane in the coating composition of the present invention is 10 to 90%, preferably 20 to 85%, more preferably 30 to 85%. This condensation rate can be determined by the ²⁹ Si-NMR method in a solution state. When the condensation rate is lower than 10%, the viscosity of the coating solution becomes insufficient, the shape retention of the coating film cannot be ensured, and the film thickness cannot be made uniform.
In addition, since gelation occurs rapidly when silica is formed, film shrinkage easily occurs. On the other hand, if the condensation rate exceeds 90%, the entire coating composition will gel. In the present invention, the condensation rate can be expressed as the ratio of the functional groups involved in the siloxane bond among the functional groups of the alkoxysilane used as the raw material of the coating composition.

The water necessary for the hydrolysis of the alkoxysilane used in the present invention is generally added as a liquid or as an aqueous solution of alcohol or the like, but it may be added in the form of steam. When water is rapidly added, depending on the type of alkoxysilane, hydrolysis and condensation may be too fast and precipitation may occur. Therefore, it is preferable to add water for a sufficient time. Therefore, when the liquid is added, it is preferable to use a method in which a solvent such as alcohol coexists so that the alkoxysilane uniformly contacts with water, or a method of adding at a low temperature is used alone or in combination. The amount of water added is preferably in the range of 0.1 mol to 5 mol per 1 mol of the alkoxysilane group charged as the raw material. When the amount of water added is in this range, the following reaction proceeds smoothly, which is preferable.

The alkoxysilane treated under the above conditions is hydrolyzed to silanol in the presence of water, and then grows into an oligomeric silica precursor having a siloxane bond by a condensation reaction between silanol groups.

The solid content concentration of the coating composition in the present invention is preferably 2 to 30% by weight as described above, but it is appropriately adjusted according to the purpose of use. When the solid content concentration of the coating composition is 2 to 30% by weight, the film thickness of the coating film is in an appropriate range and the storage stability is further excellent. The solid content concentration is adjusted, if necessary, by concentration or dilution with the solvent (C). The solid content concentration is determined as the weight of the siloxane compound obtained by hydrolysis and condensation reaction of the total amount of alkoxysilane with respect to a known amount of coating composition. In addition, the content of alkali metals such as sodium and potassium and iron in the coating composition is 5
It is preferably 0 ppb or less, and particularly preferably 10 ppb or less from the viewpoint of low leak current of the coating film. Alkali metals and iron may be mixed in from the raw materials used, (A)
It is preferable to purify the component, the component (B) and the solvent (C).

In the present invention, the solvent in the coating film is 10% after the coating composition thus obtained is coated on the substrate.
After removing 99% as described above, the coating composition is applied again, and then the component (A) is cured to obtain a composite thin film of the components (A) and (B), and then the component (B) is continuously added. It is characterized by removing.

The method of manufacturing the insulating thin film of the present invention will be described in detail below. In the present invention, the thin film is formed by applying the coating composition of the present invention onto a substrate.
As a coating method, known methods such as casting, dipping, and spin coating can be used, but spin coating is suitable for use in manufacturing an insulating layer for a multilayer wiring structure of a semiconductor element. The thickness of the thin film can be controlled in the range of 0.1 μm to 100 μm by changing the viscosity and the rotation speed of the coating composition. If it is thicker than 100 μm, cracks may occur. The insulating layer for a multilayer wiring structure of a semiconductor device is usually used in the range of 0.1 μm to 5 μm.

When an inorganic resin which is a silica precursor is used as the component (A), a coating composition containing a silica precursor is applied onto a substrate and the solvent of the coating film is removed by 10% to 99%. Then, the coating composition is applied again, and the precursor is gelated to obtain a silica / organic polymer composite thin film, and subsequently the organic polymer is removed. The Young's modulus of the porous thin film thus obtained is higher than that of the thin film obtained by applying only once.

The removal amount of the solvent in the coating composition is 10 to 99.
In the range of%, the effect of the present invention is maximized.
A more preferable amount is 50 to 99%, and further more preferably 70%.
~ 99%. The removal amount is less than 10%, conversely 99
%, Although the reason is not clear, the relative permittivity of the obtained porous thin film does not become sufficiently low, and the function as an insulating layer for a semiconductor wiring structure deteriorates. The improvement in elastic modulus is smaller than that in the case of coating, and the effect of the present invention is not maximized.

As a method for removing the solvent in the coating composition, heating in addition to the spin coating method described above is more preferable because the effect becomes more remarkable. The heating conditions, such as the heating temperature and the heating time, are not particularly limited as long as the removal amount of the solvent is controlled within the above range. The removal amount of the solvent can be determined from the weight difference before and after the coating composition and the coating film obtained by coating the coating composition on the substrate and removing the solvent are treated under reduced pressure of 150 ° C. and 100 Pa for 1 hour, respectively.

Specifically, a weight is taken out from the coating composition and treated for 1 hour under a reduced pressure of 150 ° C. and 100 Pa, and then the weight is measured to obtain b, and a and b are the standard solvent amount (ab). / B. Then, the coating composition was coated on the substrate by the coating method described above, and the solvent was removed, and the coating film was treated with the substrate at 150 ° C. under a reduced pressure of 100 Pa for 1 hour. Let c and d respectively, and the amount of solvent contained in the coating film after solvent removal is represented by (cd) / d. Therefore, the removal amount of the solvent of the present invention is 100 × [1 − [(c−d) / d] / {(a−b) /
b}]. It should be noted that c and d are represented by the weight obtained by subtracting the weight of the substrate.

The amount of coating composition used for recoating was 1
It is preferably 0.1 to 100 times, preferably 0.1 to 30 times, the weight of the coating composition for the second time. In both cases where the coating amount is less than 0.1 or exceeds 100, the elastic modulus is less improved than in the case where the Young modulus is coated once, which is not preferable. The morphological feature of the insulating thin film of the present invention is that no clear difference is observed at the boundary between the layers even when the coating composition is applied twice as described above. In addition, in coating, the same coating composition may be used, or different coating compositions may be separately coated. Further, the coating composition may be applied more than once as long as the solid content ratio is satisfied.

As the substrate, a semiconductor substrate made of silicon, germanium or the like, a compound semiconductor substrate made of gallium-arsenic, indium-antimony or the like can be used, and a thin film of another substance is formed on the surface thereof before use. Is also possible. In this case, as the thin film, in addition to metals such as aluminum, titanium, chromium, nickel, copper, silver, tantalum, tungsten, osmium, platinum and gold, silicon dioxide, fluorinated glass, phosphorus glass, boron-phosphorus glass, borosilicate. Acid glass, polycrystalline silicon, alumina,
Inorganic compounds such as titania, zirconia, silicon nitride, titanium nitride, tantalum nitride, boron nitride, hydrogenated silsesquioxane, methyl silsesquioxane, amorphous carbon, fluorinated amorphous carbon, polyimide, and any other block copolymer Thin films can be used.

Prior to the formation of the thin film, the surface of the substrate is
It may be previously treated with an adhesion improver. As the adhesion improver in this case, those used as so-called silane coupling agents, aluminum chelate compounds and the like can be used. Particularly preferably used are 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N-
(2-Aminoethyl) -3-aminopropylmethyldimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropylmethyldichlorosilane, 3-chloropropylmethyldimethoxysilane, 3- Chloropropylmethyldiethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyl Dimethoxysilane, hexamethyldisilazane, ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate), aluminum bis (ethyl acetoacetate) G) monoacetylacetonate, and the like of aluminum tris (acetylacetonate). When applying these adhesion improvers, other additives may be added, if necessary, or diluted with a solvent. The treatment with the adhesion improver is performed by a known method.

As described above, the temperature at which the coating film obtained by applying the coating composition of the present invention twice is subsequently cured (gelled) is not particularly limited, but is usually 100 to 30.
0 ° C., preferably 150 to 300 ° C. The time required for the gelation reaction varies depending on the heat treatment temperature, the amount of catalyst added and the solvent species and amount, but is usually in the range of several seconds to 10 hours. Preferably 30 seconds to 5 hours, more preferably 1 minute to
2 hours. By this operation, the gelation reaction of the silica precursor in the coating composition sufficiently progresses to form silica. The condensation rate of silica may reach nearly 100%.
It is usually about 90%. The condensation rate in this case is ²⁹ Si-
It can be determined by NMR analysis. When the temperature is lower than 100 ° C., the polymer starts to be removed before the gelation sufficiently progresses in the polymer removal step which is a post-step, resulting in the densification of the coating film. If the temperature is higher than 300 ° C, huge voids are likely to be formed,
The homogeneity of the silica / organic polymer composite thin film described below is reduced.

The silica / organic polymer composite thin film thus obtained has a low dielectric constant and is capable of forming a thick film. Therefore, it can be used as it is as an insulating part of wiring, For example optical films and structural materials,
It can also be used as a film or coating material. However, it is preferable to convert it into a porous silica thin film for the purpose of obtaining a material having a lower dielectric constant as an insulator of the LSI multilayer wiring. The silica / organic polymer composite thin film is transformed into the insulating porous silica thin film by removing the polymer from the silica / organic polymer composite thin film. At this time, if the gelation reaction of the silica precursor has proceeded sufficiently, the region occupied by the organic polymer in the silica / organic polymer composite thin film does not collapse as voids in the porous silica thin film. Remain. as a result,
A porous silica thin film having a high porosity and a low dielectric constant can be obtained.

As a method for removing the organic polymer, heating, plasma treatment, solvent extraction and the like can be mentioned, but heating is most preferable from the viewpoint that it can be easily carried out in the current semiconductor element manufacturing process. In this case, the heating temperature depends on the type of the organic polymer used, and may be simply evaporated and removed in a thin film state, may be removed by firing with decomposition of the organic polymer, and may be a mixture thereof. The heating temperature is in the range of 300 to 450 ° C, preferably 350 to 400 ° C. If the temperature is lower than 300 ° C., the removal of the organic polymer is insufficient and impurities of the organic matter remain, so that there is a risk that a porous silica thin film having a low dielectric constant cannot be obtained. Also, the amount of pollutant gas generated is large. Conversely, 450
Treatment at a temperature higher than ° C is preferable from the viewpoint of removing the organic polymer, but it is extremely difficult to use in the semiconductor manufacturing process.

The heating time is preferably 10 seconds to 24 hours. It is preferably 10 seconds to 5 hours, and particularly preferably 1 minute to 2 hours. If it is shorter than 10 seconds, the evaporation and decomposition of the organic polymer will not proceed sufficiently, so that organic substances remain as impurities in the resulting porous silica thin film, and the dielectric constant does not decrease. Moreover, since the thermal decomposition and the evaporation are usually completed within 24 hours, heating for a longer time does not make much sense. The heating is preferably performed under an inert atmosphere such as nitrogen, argon or helium. It is also possible to carry out in an oxidizing atmosphere such as mixing air or oxygen gas, but in this case, the concentration of the oxidizing gas is set so that the organic polymer is substantially decomposed before the silica precursor is gelated. It is preferable to control the concentration so that it does not occur. Further, by allowing ammonia, hydrogen, etc. to exist in the atmosphere to deactivate the silanol groups remaining in the silica, it is possible to reduce the hygroscopicity of the porous silica thin film and suppress an increase in the dielectric constant.

Since the amount of residual polymer in the porous silica thin film after removing the organic polymer of the present invention under the above heating conditions is remarkably reduced, the adhesive force of the upper layer film due to the decomposition gas of the organic polymer as described above. Phenomenon such as deterioration of the surface and peeling does not occur. The effect becomes more remarkable when the organic polymer in the coating composition of the present invention includes the polyether block copolymer and the polymer having a terminal group that is chemically inactive to the silica precursor.

In the present invention, if the step of forming the silica / organic polymer composite thin film and then the step of removing the polymer is performed under the above-mentioned conditions, a step at an arbitrary temperature and atmosphere can be performed before and after the step. There is no problem even if it passes. For heating in the present invention, a single wafer type vertical furnace or a hot plate type firing system which is usually used in the semiconductor element manufacturing process can be used. Of course, it is not limited to these as long as the manufacturing process of the present invention is satisfied.

As described above, by using the porous silica thin film of the present invention, it is possible to form an insulating film for a multi-layer wiring for LSI, which has a high mechanical strength and a sufficiently low dielectric constant. The relative dielectric constant of the porous silica thin film of the present invention can be 2.8 to 1.2 by the production method of the present invention. This relative dielectric constant can be adjusted by the content of the component (B) in the coating composition of the present invention.

One of the features of the thin film of the present invention is that the mechanical strength is sufficiently high without being affected by the relative permittivity (k). As an example, a thin film having a relative dielectric constant of 2.3 and a Young's modulus of 7.0 GPa and a thin film of k = 2.0 and a Young's modulus of 6.6 GPa were obtained. Further, in the porous thin film of the present invention, pores of 20 nm or more are not substantially observed in the pore distribution measurement by the BJH method, and it is suitable as an interlayer insulating film. The porous silica thin film obtained by the present invention is a bulk porous silica body other than a thin film, for example, an optical film such as an antireflection film or an optical waveguide, a catalyst carrier, a heat insulating material, an absorbent, a column packing material, or a caking material. Inhibitors, thickeners, pigments, opacifiers, ceramics,
It can also be used as a smoke preventive, an abrasive, a dentifrice, and the like.

[0092]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to Examples and Comparative Examples, but the scope of the present invention is not limited to these Examples. The coating composition and the thin film for producing the porous silica thin film were evaluated by the following methods. (1) Relative permittivity It was measured using an SSM495 type automatic mercury CV measuring device manufactured by Solid State Measurement. (2) Film thickness measurement It was measured using RINT 2500 manufactured by Rigaku Denki. The measurement conditions are
A graphite monochromator was set in front of the detector (scintillation counter) with a divergence slit: 1/6 °, a scattering slit: 1/6 °, and a light-receiving slit: 0.15 mm. Tube voltage and tube current were measured at 40kV and 50mA, respectively, but can be varied as needed. Further, the scanning method of the goniometer was a 2θ / θ scanning method, and the scanning step was 0.02 °.

(3) Young Modulus Nano Indenter DCM manufactured by MTS Systems Corporation
It was measured at. The measurement method was as follows: A Berkovich type diamond indenter was pressed into a sample, and after a certain load was applied, the load was removed and the load-displacement curve was obtained by monitoring the displacement. The surface was recognized under the condition that the contact stiffness was 200 N / m. The hardness is calculated by the following formula. H = P / A Here, P is the applied load, and the contact area A is a function of the contact depth hc and was experimentally obtained by the following equation.

[0094]

[Equation 1]

This contact depth has the following relationship with the displacement h of the indenter. hc = h-εP / S where ε is 0.75 and S is the initial slope of the unloading curve.

The Young's modulus was calculated by Sneddon's formula. Er = (√π · S) / 2√A Here, the composite elastic modulus Er is expressed by the following equation. ^{Er = [(1-νs 2} ) / Es + (1-νi 2) / Ei] -1 where, [nu is the Poisson's ratio, the subscript S samples, i is representative of the indenter. In the present invention, νi = 0.07, Ei = 11141G
Pa, and the Poisson's ratio of this material is unknown, but νs =
The Young's modulus Es of the sample was calculated as 0.18. The Young's modulus in the present invention is 0.8
It was measured at a film thickness of μ to 1.2 μm.

[0097]

Example 1 Tetraethoxysilane 7.94 g, dimethyldiethoxysilane 1.14 g, methyltriethoxysilane 1.01 g, ethanol 13.53 g, water 9.71
g, and 2.06 g of 0.1 mol / l nitric acid,
The mixture was stirred at 5 ° C for 5 hours for reaction. The solution was heated at 50 ° C, 66
After distilling off the solvent at 00 Pa and concentrating to 18.1 g, 25.94 g of ethyl lactate and 10 g of water were added. Polyethylene glycol-polypropylene glycol-polyethylene glycol (number average molecular weight 6
400, 2.42 g of polypropylene glycol moiety having a number average molecular weight of 3200) was added to obtain a coating composition of the present invention.

3 ml of this on a 6 inch silicon wafer
It was dropped, spin coated at 1050 rpm for 60 seconds at room temperature, and heated in air on a hot plate at 120 ° C. for 1 minute. The removal rate of the solvent in this case was 90%. Next, 3 ml of the same coating solution was dripped and spin-coated at 1050 rpm for 60 seconds, then in air at 120 ° C. for 1 minute, under nitrogen atmosphere at 200 ° C. for 1 hour, and then under nitrogen atmosphere at 40 ° C.
It was heated and baked at 0 ° C. for 4 hours to obtain a porous silica thin film having a film thickness of 0.95 μm. The obtained thin film has a relative dielectric constant of 2.0 at 1 MHz and a Young's modulus of 6.4 GPa.
Met.

[0099]

Example 2 The same operation as in Example 1 except that 1.04 g of 2.42 g of polyethylene glycol-polypropylene glycol-polyethylene glycol used in Example 1 was replaced with polyethylene glycol dimethyl ether (number average molecular weight 600). And the film thickness is 0.9
A 0 μm porous silica thin film was obtained. The solvent removal rate of the coating film applied the first time and subjected to hot plate treatment was 91%. 1 of the porous silica thin film obtained after applying twice
The relative dielectric constant at MHz was 2.0 and the Young's modulus was 6.6 GPa.

[0100]

Example 3 Of 2.42 g of polyethylene glycol-polypropylene glycol-polyethylene glycol used in Example 1, 1.04 g was replaced with polyethylene glycol dimethyl ether (number average molecular weight 600), and further on a hot plate at 120 ° C. for 3 minutes. The same operation as in Example 1 was carried out except that the film was heated to a film thickness of 0.93.
A porous silica thin film of μm was obtained. The solvent removal rate of the coating film applied for the first time and subjected to hot plate treatment was 96%. 1 of the porous silica thin film obtained after applying twice
The relative dielectric constant in MHz was 2.3, and the Young's modulus was 7.0 GPa.

[0101]

[Comparative Example 1] 3 ml of the coating solution prepared in Example 1 was dropped on a 6-inch silicon wafer, and the coating solution was applied at 60 rpm at 500 rpm.
The same operation as in Example 1 was carried out except that spin coating was carried out for 2 seconds and then baking was performed to obtain a porous silica thin film having a film thickness of 0.95 μm. The relative permittivity of the obtained thin film at 1 MHz is 2.
0, Young's modulus is 4.3 GPa, Example 1
Although the relative permittivity is similar to that of, the mechanical strength was inferior.

[0102]

Comparative Example 2 3 ml of the coating solution prepared in Example 1 was dropped on a 6-inch silicon wafer and spin-coated at room temperature at 50 rpm for 10 seconds. Solvent removal rate in this case is 7%
Met. Next, 3 ml of the same coating solution was dropped again, and 105
120 minutes in air after spin coating at 0 rpm for 60 seconds
C. for 1 minute, under nitrogen atmosphere at 200.degree. C. for 1 hour, and then under nitrogen atmosphere at 400.degree. C. for 4 hours to obtain a porous silica thin film having a thickness of 0.95 .mu.m. The obtained thin film had a relative permittivity of 2.0 at 1 MHz and a Young's modulus of 4.6 GPa.

[0103]

Example 4 Tetraethoxysilane 4.0 g, methyltriethoxysilane 12.33 g, water 8.31 g, polyethylene glycol dimethyl ether (number average molecular weight 60
0) 12.73 g, 0.1 mol / l nitric acid 2.15 g
Were mixed and reacted at 40 ° C. with stirring for 5 hours. The solvent was distilled off from the solution at 50 ° C. and 6600 Pa to give 24.88.
After concentrating to g, ethyl lactate 13.36 g, water 10
g, and coating composition 1 was obtained. In addition, 13.92 g of tetraethoxysilane and dimethyldiethoxysilane 2.
08 g, ethanol 24.72 g, water 16.96 g, polyethylene glycol-polypropylene glycol-polyethylene glycol (number average molecular weight 6400, number average molecular weight of polypropylene glycol part is 3200)
2.52 g and 3.44 g of 0.1 mol / l nitric acid were mixed and reacted at 40 ° C. for 5 hours with stirring. The solution 63.
The solvent was distilled off from 3 g at 50 ° C. and 6600 Pa, and 22.
After concentrating to 38 g, 44.93 g ethyl lactate, 1 water
6.8g was added and the coating composition 2 was obtained. Coating composition 1
3 ml is dropped on a 6 inch silicon wafer, and 105
Spin coating at 0 rpm for 60 seconds, then 120 in air
Heated at 0 ° C for 1 minute. The solvent removal rate of the coating film at this time was 93%. Next, 3 ml of the coating composition 2 was further dropped and spin coated at 1050 rpm for 60 seconds. This was baked in air at 120 ° C. for 1 minute, under a nitrogen atmosphere at 200 ° C. for 1 hour, and then under a nitrogen atmosphere at 400 ° C. for 1 hour to obtain a porous silica thin film having a thickness of 0.9 μm. . The relative permittivity of this thin film at 1 MHz was 2.2, and the Young's modulus was 5.8 GPa.

[0104]

Comparative Example 3 9.21 g of the coating composition 2 of Example 4 was added to 0.79 g of the coating composition 1, and the mixture was stirred at room temperature for 30 minutes to obtain a mixed coating composition. 3 ml of this mixed coating composition was dropped on a 6-inch silicon wafer to obtain 500 r
It was spin coated at pm for 60 seconds. Then 120 ° C in air
For 1 minute, then 200 ° C for 1 hour in a nitrogen atmosphere, 4
The porous silica thin film having a thickness of 0.9 μm was obtained by firing at 00 ° C. for 1 hour. The thin film has a relative permittivity of 2.2 at 1 MHz and a Young's modulus of 4.5 GPa, and the relative permittivity is about the same as when the compositions 1 and 2 of Example 4 are separately applied, but the mechanical strength is inferior.

[0105]

Example 5 Tetraethoxysilane 17.54 g, bistriethoxysilylethane 13.4 g, dimethyldiethoxysilane 5.04 g, ethanol 61.8 g, water 4
8.2 g and 0.285 g of 0.1 mol / l oxalic acid were mixed and reacted at 50 ° C. for 5 hours with stirring. The solution 3
Taking 6.56 g, polyethylene glycol-polypropylene glycol-polyethylene glycol (number average molecular weight 6400, number average molecular weight of polypropylene glycol part is 3200) 0.392 g, polyethylene glycol dimethyl ether (number average molecular weight 600) 1.96
2 g was added and the solvent was distilled off at 50 ° C. and 6600 Pa,
It was concentrated to 9.667 g. From this, 8.458 g was taken, and propylene glycol methyl ether 13.
206 g, 1.11 g of water and 0.116 g of ethanol were added to obtain a coating composition of the present invention. 3 ml of this composition was dropped on a 6-inch silicon wafer, and the composition was added at 1050 rpm for 6
It was spin coated for 0 seconds and heated on a 120 ° C. hot plate for 1 minute. The solvent removal rate of this coating film was 91%. Further, 3 ml of the same coating composition was dropped and spin coated at 1050 rpm for 60 seconds. After that, the film is baked in air at 120 ° C. for 1 minute, at 200 ° C. for 1 hour in a nitrogen atmosphere, and subsequently at 400 ° C. for 1 hour in a nitrogen atmosphere to give a film thickness of 1.2 μm.
A porous silica thin film of m was obtained. 1MHz of the obtained thin film
Has a relative dielectric constant of 2.1 and a Young's modulus of 6.4.
It was GPa.

[0106]

The porous silica thin film according to the present invention has a sufficiently low relative permittivity and is stable and can sufficiently withstand the CMP process in the copper wiring process of a semiconductor device. Therefore, it can be used for an LSI multilayer wiring substrate or an insulating film of a semiconductor device. As is the best.

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) H01L 21/316 H01L 21/316 G 21/768 21/90 QV F Term (Reference) 4F071 AA44 AA51 AA67 AA81 AC16 AG27 AH16 BB02 BC01 4J002 BG041 CF031 CG011 CH021 CH041 CH051 CP052 EX036 GQ05 5F033 GG00 GG02 HH04 HH07 HH08 HH11 HH13 HH14 HH17 HH18 HH19 HH21 HH32 HH33 QQ04 QQ48 RR01 RR03 RR04 RR06 RR09 RR11 RR13 RR14 RR15 RR21 RR22 RR24 RR25 RR29 SS00 SS22 XX01 XX24 5F058 AA10 AC03 AF04 AG01 AH02

Claims (5)

[Claims] 1. Containing (A) an electrically insulating inorganic or organic component, (B) a substance capable of volatilizing or generating a gas by heat in a temperature range of 0 to 500 ° C., and (C) an organic solvent. A method for producing an insulating thin film, which comprises producing the insulating thin film through the following steps 1 to 3 using the coating composition. Step 1: A step of applying the coating composition to the surface of the base material. Step 2: A step of removing the solvent in the coating film obtained by coating from 10% by weight to 99% by weight before and after the treatment, and then re-coating the coating composition in the same manner as in step 1. Step 3: A step of removing the component (B) after curing the component (A) in the coating film obtained in the step 2. 2. The component (A), (B) and (C) according to claim 1, wherein the component (A) is an alkoxysilane represented by the following general formula (1) and / or general formula (2) and its hydration. A silica precursor containing at least one compound selected from decomposition products and polycondensates; and R ¹ _n (Si) (OR ² ) _4-n (1) (wherein R ¹ is hydrogen or monovalent Represents an organic group of and R ² is 1
-Valent organic group, n is an integer of _{^{0~3) R 3 m (R 4}} O) 3-m Si- (R 7) p -Si (OR 5) 3-q R 6 q (2) (R ³ and R ⁶ may be the same or different and represent hydrogen or a monovalent organic group, R ⁴ and R ⁵ may be the same or different and each represents a monovalent organic group, m And q, which may be the same or different, each represents a number of 0 to 2, R ⁷ represents a group represented by an oxygen atom-or (CH ₂ ) r-, r is 1 to 6, and p is 0 or 1.) (B) at least one organic solvent selected from the group consisting of linear or branched organic polymers, (C) alcohol-based solvents, ketone-based solvents, amide-based solvents and ester-based solvents The method for producing an insulating thin film according to claim 1, wherein 3. The organic polymer according to claim 2, wherein the linear or branched block copolymer of two or more elements and at least one of the end groups of the organic polymer are chemically inert to the silica precursor. The method for producing an insulating thin film according to claim 1, further comprising one or more organic polymers having different groups. 4. A wiring structure using an insulating thin film obtained by the manufacturing method according to claim 1. 5. A semiconductor device including the wiring structure according to claim 4.