JPS63278977A - Composition for forming thick-film insulator - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in an ability to fill holes among fine patterns, flatness, cracking resistance, etc., by mixing a specified siloxane prepolymer obtained by polymerization through cohydrolysis of a tetraalkoxysilane with an organic solvent. CONSTITUTION:A copolymer is produced by polymerization through cohydrolysis of a particulate or reticular, segment-forming polymer (A) obtained from a tetraalkoxysilane of formula I with a component for bonding component A, which is a trialkoxysilane of formula II, a dialkoxysilane of formula III or a mixture of at least two members selected from the compounds of formulas I, II and III or a precondensate thereof. The obtained siloxane prepolymer is mixed with an organic solvent (e.g., methanol) to obtain the purpose composition for forming thick-film insulators.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a novel composition for forming glasses for insulating films, capacitors, etc. used in the semiconductor industry.

For details, after application by spin cord or dipping,
The present invention relates to a composition that can form a thick film insulator by a heat treatment method or the like.

<Conventional technology> Insulating film for semiconductors is polysilicon and aluminum cAe>
In addition to being used for insulation purposes between wiring layers and between Ae wiring layers,
It is also widely used for purposes such as PN junction protection, element surface protection, and filling of trenches for isolation between elements. Methods for forming insulating films 1 Generally, the vapor phase growth method and the coating film method are known, and the former is generally used, but this method requires special equipment and processing. There are problems such as there are restrictions on the size of the base material to be used, and it is difficult to produce large wax.

Furthermore, one problem with the increasing stacking of semiconductors is that the grooves between patterns are becoming narrower, and the unevenness of the element surface is becoming larger. Conventional vapor phase methods are too dependent on the surface structure, so it is difficult to improve insulation properties. It has become difficult to guarantee this. From this point of view, coating film methods with excellent flatness are being reconsidered.

Many coating films are currently proposed. Typical organic materials include polyimide and polyimide silicone, but although these have excellent flatness and crack resistance, they have poor heat resistance, polysilicon, and polysilicon (J?, 5).
iO1, Si@N, etc. (y) They have poor adhesion to the substrate, and there is also the problem of deterioration due to long-term oxidation. In particular, a major drawback is that partial decomposition occurs at temperatures above 450°C.

On the other hand, silica glass-based coatings, typically made of polycondensates of tetraethoxysilane, have excellent heat resistance and adhesion to substrates, but have poor crack resistance.
It has the disadvantage that it can only be used for applications with a maximum film thickness of 6.0 OOA or less.

It also has the disadvantage that it cannot completely fill a groove with a width of 1 .mu.m and a depth of 1 .mu.m.

Furthermore, even in the case of reacting an organosilica sol with an alkyl silicate (Japanese Unexamined Patent Publication No. 61-291665), a film with a film thickness exceeding 1 μm with good adhesion and no cracks was obtained.

On the other hand, there have been proposals for composites of polyladder organosiloxane and polyladder organosiloxane with silica glass, etc., but these are not practical due to poor adhesion to the substrate, crack resistance, and film uniformity (Unexamined Japanese Patent Publication No. Showa 57-8856
No. 8, JP-A-57-181250, JP-A-56-12
9261, etc.).

Furthermore, the proposal of polydihydrodiene siloxane in Japanese Patent Application Laid-open No. 60-86018 is that it is heated at 460°C for 1 hr under an oxygen atmosphere.
Time baking is required, and Ink is about 10%
An increase in the degree occurs.

Furthermore, since the volume increases, the effect on the device cannot be ignored, and if the film thickness is increased, oxygen diffusion becomes insufficient, making it difficult to obtain uniform film quality.

<Problems to be solved by the invention> Under the current situation, the problems to be solved by the inventor are as follows.
It is stable with at least 600 CICtct, can sufficiently fill the grooves between fine patterns, has good adhesion to the substrate, can be flattened, and can be used even if the film thickness exceeds 2.0 μm. An object of the present invention is to provide a composition for forming a thick film insulator that does not cause cracks.

Measures to solve problems > The basic coating film method is to dissolve the base polymer that forms the film in an organic solvent, apply it to the substrate by dipping or spin-coding, and then heat it to dissolve the organic solvent. It consists of removal and thermal condensation polymerization to form a lath or macromolecular film.

In order to obtain a film with good flatness and no cracks on a wiring pattern with a step, it is necessary that a flat wafer is free from cracks at a film thickness that is at least equal to the depth of the step. For example, a pattern with a step height of 1.8 μm (18,000 people) has a step height of at least 2.0 p m (20,000 people).
It is necessary to have a film thickness of 0OOA) and no cracks.

As a result of various studies on compositions that satisfy the above conditions, the inventor found that the film thickness after heat treatment at 400°C or higher was 2.0 μm.
As described above, we have developed a composition that provides a film with no cracks and have completed the present invention.

That is, the present invention provides an insulating film forming composition comprising a siloxane prepolymer obtained by hydrolyzing and condensing an alkoxysilane and an organic solvent, in which the siloxane prepolymer forms the following particulate or network segments. A composition for forming a thick film insulator, which is a copolymer obtained by co-hydrolytic condensation of a polymer (2) and a component (B) that binds the polymer (2). It is.

(a) Polymer obtained from tetraalkoxysilane represented by general formula (a): 5i(OR1)4 (a) Trialkoxysilane represented by general formula (b): R'5i(OR1)3, general Formula (c): R'R
Dialkoxysilane represented by '5i(OR')1, or two or more alkoxysilane compounds selected from general formula (a), general formula (bl, general formula (c)), or a low condensate thereof ( Component (a (in the formula R1,
R1, R3, R4, R11 and R6 represent an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 10 carbon atoms. ) The hydrolytic condensation reaction of tetraalkoxysilane is generally carried out in the presence of an acid or alkali catalyst and water.

It is known that the structure of the polymer obtained by the hydrolytic condensation reaction of tetraalkoxysilane is influenced by the type and amount of catalyst, amount of water, type of alkoxy group, type of solvent, reaction conditions, etc. .

In particular, when an alkali catalyst or an acid catalyst is used and the amount of water is in excess of 2 moles or more per mole of tetraalkoxysilane, the polymer tends to have a particulate or network structure.

These matters are discussed, for example, in Masao Sakuhana, Hiroshi Kamiya-0 Journal of the Japanese Society of Rheology, Vol. 14, P, 9-P, 17 (1986).
;S, 5AKKA, K, KAMIYA, J, Non
-Cryst, 5olids, volo, 48.
P, 8L-P46 (1982), etc.

In the present invention, the polymer (Al) forming the particulate or network segments is a tetraalkoxysilane mixed with 4 to 20 mol of water per 1 mol of the tetraalkoxysilane, an acid or alkali catalyst, and, if necessary, a solvent. It is obtained by hydrolytic condensation and polymerization.

Specific examples of the tetraalkoxysilane represented by the general formula (a): S i (OR')4 include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetraisobutoxysilane, tetraphenoxysilane, etc. . In particular, tetramethoxysilane and tetraethoxysilane are preferably used. Solvents include alcohols such as methanol, ethanol, and impropatol, ketones such as acetone and methyl ethyl ketone, and cyclic ethers such as tetrahydrofuran and dioxane.
A solvent that can mutually dissolve tetraalkoxysilane and water can be used.

The reaction temperature is 150C or higher, preferably 0 to 100C.
It is C. Further, the turbidity at the time of reaction varies depending on the reaction temperature 1ζ, and is appropriately selected so as to exceed the above-mentioned average molecular weight. The molecular part of the polymer iAl is the weight average molecule mc41 determined by GPC.
It is 2,000-100,000 (in terms of quasi-polystyrene), preferably 4,000-50,000. A component that binds aggregates 4 that form particulate or network segments (81 is trialkoxysilane represented by general formula (b), dialkoxysilane represented by general formula (c), or general formula +1) Tetraalkoxysilane represented by the general formula (trialkoxysilane represented by bl, dialkoxysilane represented by the general formula (c) 2) 7 ° lukoxysilane compound with iJ or more,
or these low condensates (oligomers), (when Al and <81 are co-hydrolyzed to 1M+!, (B) itself becomes a polymer by hydrolytic condensation and polymerization, and at the same time 6
It becomes a component that binds (A) through polycondensation between ζ, ^) and β).

Specific examples of the trialkoxysilane represented by the general formula (b) (S i (OR')) include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, and ethyltriethoxysilane. Examples include silane, ethyltriisopropoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriisopropoxysilane, and the like. Preferred are methyltrimethoxysilane and methyltriethoxysilane.

General formula (c): R'R'IS i (OR@)t
Examples of Al dialkoxysilanes include dimethyldimethoxysilane, dimethyljethoxysilane, dimethyldiimpropoxysilane, diethyldimethoxysilane, diethyljethoxysilane, diethyldiynepropoxysilane, diimpropyldimethoxysilane, diisopropyljethoxysilane, Examples include diisopropyldiynepropoxysilane, diethyljethoxysilane, diphenyljethoxysilane, diphenyldiynepropoxysilane, and the like.

Particularly preferred are 1ζ dimethyldimethoxysilane, dimethyljethoxysilane, and diphenyljethoxysilane.

In the component (Bl +), the low condensate (oligomer) is
A morph of an alkoxy group possessed by trialkoxysilane, dialkoxysilane, or two or more alkoxysilanes selected from tetraalkoxysilane, trialkoxysilane, and dialkoxysilane, is partially dissolved using 4 to 2.0 times as much water. It is obtained by hydrolytic condensation polymerization, and the molecular weight is 500 to a, o in Maki average -F- amount by GPC.
It's o o. At this time, solvents include alcohols such as methanol, ethanol, and impropano-I, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran,
A solvent that mutually dissolves water and an alkoxysilane such as cyclic ethers such as dioxane can be used, but the solvent is not essential.

When synthesizing a siloxane-based prepolymer by co-hydrolyzing and condensing polymer 1 and component (Bl), general formula (a) and general formula (b) are used in (A4 and β).

The usage ratio of alkoxysilane represented by general formula (c1) is a value representing the ratio of alkyl groups bonded to Si defined by formula (1), and is desirably 0.50 to 1.50, preferably 0.56 to 1.80. If it is smaller than 0.60, there will be too much tetrafunctional component in the siloxane prepolymer, making it impossible to obtain a thick film without cracks, while if it is larger than 1.50, it will not be possible to obtain a thick film without cracks. This is unsuitable because the membrane shrinkage becomes large at times, resulting in not only poor flatness but also poor adhesion to the substrate.

In addition, the proportion of the polymer FAI forming particulate or network segments in the siloxane prepolymer is preferably 0.05 to 0.75 in terms of silicon mole fraction, and preferably 0.09 to 0.50. It is preferable that there be. If the molar fraction is larger than 0.76, there are too many tetrafunctional components in the siloxane-based prepolymer) ζ Therefore, if the film thickness after coating is 2.011 m or more, cracks are likely to occur.
．． If it is smaller than 0.05, there are too few waves in the particulate or mesh segments, and a film with good crack resistance cannot be obtained.

When the cohydrolysis lines of polymer (~ and (Bl) meet, excess water is used when synthesizing the polymer (~), so there is no cohydrolysis in the liquid of the synthesized polymer (~). There is no need to add new water because it contains enough water for decomposition and condensation polymerization.When reacting the polymer (~ solution with component (B), gradually add (Bl) Alternatively, (81) may be gradually added with the liquid of In order to prevent heterogeneous reaction, it is preferable to add ζ gradually.The reaction temperature when cohydrolyzing and condensing 4 and (81) is 150°C or higher, preferably 0 to 100°C.Reaction The time is appropriately selected depending on the reaction temperature, but is generally 80 minutes to 3 hours.If the concentration of one reaction system is too high, it will be difficult to control the molecular weight and gelation will easily occur.In addition, it is desirable if it is too low. Since it takes a long time to carry out the cohydrolytic condensation reaction until the molecular weight is reached, the concentration of the reaction system is preferably 0.6 to 6 mol/e, and 1 to 5 mol/e in molar concentration of silicon atoms per tg of reaction solution. It is favorable for the river to be.

The molecular weight of the siloxane prepolymer obtained by this cohydrolysis condensation polymerization 1ζ is preferably to, 000 to t, o o o, o o o, and more preferably i o, o o o~
It is 500.000.

The above-mentioned siloxane prepolymer solution can be made into a desired coating solution by concentrating it using an evaporator or adding an organic solvent. Examples of organic solvents include alcohol solvents such as methanol, ethanol, and impropatul, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ethylene glycol monoalkyl ether solvents such as butyl seyan rub, and l-methoxy-2- Examples include organic solvents such as propylene glycol hexachloroether (mM) such as propylene glycol, and aromatic solvents such as benzene and toluene.

Mixture 1 of such a siloxane prepolymer and an organic solvent
The concentration of the siloxane polymer in ζ is determined as appropriate depending on the usage situation, but generally it is 4v1 in terms of Sin! t% or more, and 10ta% or more is preferably used.

To form an insulating film, first carefully apply the above insulating film forming coating solution using the commonly used spin code method or dipping method, then air dry or heat at a low temperature to thoroughly remove the solvent.
Heating to a temperature of 0°C or higher to decompose unreacted alkoxy groups and form siloxane bonds in these parts.
It is done from here.

<Example> The present invention will be described in more detail below using Example F, but the present invention is not limited to these embodiments.

Example 1 Tetraethoxysilane 88.8f Ethanol and 46.8f
7f proverb and 0.6N hydrochloric acid-ethanol solution 1.5-1000m with a reflux device? A four-bottle flask was placed in the flask, and a mixture of 72 F of M water and 40 F of ethanol was added thereto over 2 hours while stirring at room temperature. Then, the temperature was raised to 1 under reflux.
Hydrolysis and condensation of tetraethoxysilane was carried out by reacting for a period of time. After cooling to room temperature, the water concentration in the above liquid is 22
．． 4% by weight, weight average molecular weight by GPC is 7,400
Met.

Next, 242 t of an ethanol solution of one combination of the above tetraethoxysilane was put into a 1000 d four-neck flask with a reflux device, and a mixture of 70.8 F of tetraethoxysilane, 81.9 F of methyltriethoxysilane, and 109.7 F of dimethyljethoxysilane was added. was added over 1 hour while stirring at room temperature. Next, the temperature was raised and the mixture was allowed to react under reflux for 1 hour to perform cohydrolytic condensation polymerization. The water concentration in the liquid after the reaction was 1.9% by weight, and the weight average molecular weight of the copolymer by GPC+ was 9. It was lOO.

A 100 F ethanol solution of the above copolymer was concentrated in an evaporator to 80 F, filtered through a 0.2 μm filter, and then formed into a trowel coating film at 1 or 2 O rpm on a silicon wafer. 1 in °C
The film was heat-treated for 0 minute and then at 450°C for 80 minutes to form a cured film. The film thickness was 2.18 μm and no cracks were observed.

Example 2 Tetraethoxysilane 125F, ethanol 26,7
f and 1.5 d of 0.6 N hydrochloric acid-ethanol solution were placed in a 1000-four-hole flask equipped with a reflux device, and 57 F pure water was added.
and 80 tons of ethanol at room temperature while stirring.
The mixture was added over a period of time, and then heated and reacted under reflux for 2 hours to perform hydrolytic condensation polymerization to obtain an ethanol solution of a tetraethoxysilane polymer. The water concentration in the liquid is 14
．． 5 Jusha%, the average molecular weight of the polymer by GPC is 4
It was 0,900.

Next, put 240 f of the ethanol solution of the above tetraethoxysilane polymer into a four-hole flask equipped with a reflux device, and add 107 f of methyltriethoxysilane.
A mixture of 89 tons of dimethyljethoxysilane was added over 1 hour while stirring at room temperature. Next, the temperature was raised and the mixture was reacted for 1 hour under reflux to perform cohydrolytic condensation polymerization. The water concentration in the liquid is 2.2iJi1%, and the average molecular weight of the copolymer according to GPCI is 47. It was l 00.

120 t of the ethanol solution of the above-mentioned co-merger was concentrated in an evaporator to 100 f, filtered through a 0.2 μm filter, and then spin-coated on a silicon wafer at Iζ 11000 rp to form a coating film, which was heated at 180° C. for 10 minutes, and then A cured film was obtained by heat treatment at 460° C. for 80 minutes.

The film thickness was 2.87 μm, and no cracks were observed.

Example 8 Dimethyljethoxysilane l O4,8F, 1.2
Pour 6 liters of N hydrochloric acid-ethanol solution into a four-bottle flask, and add pure water to 10.2F while stirring at room temperature.
was added over about 5 minutes. When adding pure water, the liquid temperature was raised from 20°C to 46°C, and stirring was continued for 80 minutes after the addition to perform partial hydrolytic condensation of dimethyljethoxysilane. This] Komethi Retriethoxysilane 104.
Add 8F and add about 12.7F of pure water while stirring.
It was added for 0 minutes to cause the low condensate of dimethyljethoxysilane and methyltriethoxysilane to react. Add 147v of tetraethoxysilane and 20.4f of distilled water to 50
After adding the co-product for 1 minute, the liquid temperature was raised to 60℃ (this temperature was increased to 60℃)
Allowed to react for minutes. Furthermore, after distilling off by-product ethanol, hydrochloric acid and unreacted water under pressure, ethanol was added and the mixture was heated to 400 ml.
It was set as f. .

The water content in the ethanol solution of the alkoxysilane low condensate obtained in this way is 0.05111 t% or less,
The direct average molecular multiplication by GPCI was 1,150.

Ethanol solution of the above alkoxysilane low condensate too
f, 80f of the ethanol solution of the tetraethoxysilane polymer obtained in Example 2, and 1st of the 0.6N #1 acid-ethanol solution were placed in a 5004-four-hole flask equipped with a reflux device, and reacted under reflux for 1 hour to give a co-liquid. Hydrolytic condensation polymerization was performed. Moisture a change in the solution after reaction is 4.7% sulfuric acid, GP
The average molecule-m of one company based on Ct was 88,700.

An ethanol solution of 1 oz of ethanol was concentrated to 78F using an evaporator. After filtering this with a 0.2 μm filter, it was transferred to silicon wafer soil with 1.2001”
Spin code with pm to form a coating film and heat it at 180°C.
The film was heat treated at 460C for 10 minutes and then at 460C for 80 minutes to form a cured film.

The film thickness was 2.80 μm, and no cracks were observed.

Example 4 Dimethyljethoxysilane 178. Of, 6 ml of a 1.2 N hydrochloric acid ethanol solution was put into four 1000 m/Low flasks, and 17.8 F pure water was added while stirring at room temperature, and one partial raw water decomposition line of dimethyljethoxysilane was performed. This] Memethyltriethoxysilane 1
8F of pure water was added thereto, and 8.7F of pure water was further added over 10 minutes with stirring.

fi (tetraethoxysilane 8B, 8f and distilled water L)
L and 5F were co-added over 80 minutes, and the liquid temperature was raised to 50C and reacted for 80 minutes. Subsequently, by-product ethanol, 4 acids, and unreacted water were distilled off under reduced pressure, and then ethanol was added.
I adjusted it so that it was 00f. 200 g of an ethanol solution of the low condensate of the above ayakoxysilane and an ethanol solution of the tetraethoxysilane polymer obtained in Example 2
r and 0.6 N hydrochloric acid ethanol solution 2 at were placed in a 1000 d four-neck flask equipped with a reflux device, and reacted under reflux for 1 hour to perform cohydrolytic condensation polymerization. The water concentration in the solution after the reaction was 5.1%, and the average molecular weight according to GPC+ was aoo, ooo.

After concentrating the ethanol solution 2001 of the above-mentioned coelectrolyte to 120 f using an evaporator, the butyl cellulol was added to 8
Added 6t6. After filtering this with a 0.2 μm filter, a coating film was formed on silicone Ueno 1 by spin-coding at SO rpm, and heat treated at 180°C for 10 minutes and then at 450°C for 80 minutes to form a cured film. did. The film thickness was 8.47 μm and no cracks were observed.

Example 5 The coating solution obtained in Example 4 was applied to silicone Ueno 1-E:
A turret film was formed by spin-coding at 1000 rpm, which was then incubated at 180°C for 10 minutes and then at 450°C for 80 minutes.
A cured film was obtained by heat treatment for a minute.

The film thickness was 8.17 μm. When the film was further heat-treated with toooc for 80 minutes, the film thickness was 2.6 μm, and no cracks were visible.

Comparative Example 1 An ethanol solution 1209 of the tetraethoxysilane polymer obtained in Example 2 and 0.5 ml of a 0.6 N hydrochloric acid ethanol solution were placed in a 500-ton 4-bottle flask (with a reflux device), and dimethyljethoxysilane L2f was added to the ethanol solution 1209 obtained in Example 2. It was added over 20 minutes while stirring at room temperature, and was reacted for one hour under reflux to perform cohydrolytic condensation polymerization. 5 toof of the above copolymer dissolved in ethanol was concentrated in an evaporator to 70F, and After passing through a 2 μm filter, the coating solution of Comparative Example 1 was obtained.

Comparative Example 2 A 120F ethanol solution of the tetraethoxysilane heel combination prepared in Example 1 and a 0.6N hydrochloric acid-ethanol solution were placed in four 500gt flasks equipped with a reflux device, and dimethyljethoxysilane 118.6F was heated to room temperature. The mixture was added over 1 hour while stirring, and reacted under reflux for 1 hour to perform cohydrolysis and condensation polymerization. Concentrate the ethanol solution of the above-mentioned co-monomer to 80f using an evaporator, and
．． After passing through a 2 μm 74 router, the coating solution of Comparative Example 2 was obtained.

Comparative Example 8 120 tons of the ethanol solution of the tetraalkoxysilane polymer obtained in Example 2 and 0.5-liter of 0.6N hydrochloric acid in ethanol were placed in a 500 m 14 flask equipped with a reflux device, and methyltriethoxysilane 4B, 8R was heated to room temperature. The mixture was added over 40 minutes while stirring, and reacted under reflux for 1 hour to perform cohydrolytic condensation polymerization. A solution of 1100 f of the above copolymer in ethanol was concentrated to 80 f using an evaporator, and after passing through a 0.2 μm filter, a coating solution of Comparative Example 8 was obtained.

Comparative Example 4 A 200F ethanol solution of the low condensate of alkoxysilane obtained in Example 8 and a 0.6N ethanol solution 80F of a combination of the tetraalkoxysilane obtained in Example 1
Condensation polymerization was carried out in the same manner as in Example 8 using a hydrochloric acid ethanol solution L d to obtain a coating liquid of Comparative Example 4.

The coating liquids of Examples 1 to 4 and Comparative Examples 1 to 4 were formed into films using a spin cord, and the results of observing the film surface state after heat treatment at 450° C. for 280 minutes are shown in Table 1.

Table 1 <Effects of the Invention> The present invention has solved the problems of hydraulicity between fine patterns and flatness, which are disadvantages of the vapor phase method, and at the same time greatly improved the crack resistance, which was a disadvantage of coating films. Provided is a composition for forming a thick film insulator that improves the properties of the film and does not cause cracking even when the film thickness exceeds 2 μm, and is used as a coating liquid for forming glass for insulating films, capacitors, etc. used in the semiconductor industry. .

Claims (4)

[Claims] (1) In an insulator-forming composition consisting of a siloxane prepolymer obtained by hydrolyzing and condensing an alkoxysilane and an organic solvent, the siloxane prepolymer forms the following particulate or network segments: (A)
1. A composition for forming a thick film insulator, which is a copolymer obtained by co-hydrolytic condensation of and a component (B) for bonding between polymers. (A) General formula (a): Polymer (A) obtained from tetraalkoxysilane represented by Si(OR^1)_4
b) Trialkoxysilane represented by general formula (b): R^2Si(OR^3)_3, general formula (c): R^4R
Dialkoxysilane represented by ^5Si(OR^6)_2, or general formula (a), general formula (b), general formula (c)
A component that is two or more types of alkoxysilane compounds or low condensates (oligomers) thereof selected from (in the formula R^1, R^2, R^3, R^4, R^5, and R^4 is an alkyl group having 1 to 5 carbon atoms or 6 to 10 carbon atoms
represents an aryl group. ) (2) Claim 1, wherein the polymer (A) is obtained by hydrolyzing and condensing a tetraalkoxysilane represented by the general formula (a) using 4 to 20 moles of water per mole of tetraalkoxysilane. The composition for forming a thick film insulator as described above. (3) Polymer (A) in siloxane prepolymer
2. The composition for forming a thick film insulator according to claim 1, wherein the molar fraction of silicon is 0.05 to 0.75. (4) The composition for forming a thick film insulator according to claim 1, wherein the siloxane prepolymer has a value defined by formula (1) of 0.50 to 1.50. thing. (Formula 1) General formula (b) + General formula (c) x 2 General formula (a) + General formula (b) + General formula (c) (However, each of General formula (a), (b), and (c) The unit of usage is number of moles)