JP7689434B2 - Dihydrodisiloxane compound and its manufacturing method - Google Patents

Description

The present invention relates to a dihydrodisiloxane compound useful for producing silicon-containing thin films and a method for producing the same.

Silicon dioxide (silica) is a typical metal oxide material that has both high chemical and thermal stability and good physical properties (transparency, insulation, mechanical strength), and is used industrially in various forms from bulk to nano-sized materials. The main methods for producing thin silica films are wet and dry methods, but the dry method of chemical vapor deposition (CVD) is mainly used because it requires fewer steps and is easy to obtain high-density, high-performance films. In particular, in order to impart high oxygen and water barrier properties to polymer film materials, a transparent silica film is deposited on the film by the CVD method to achieve this purpose. In film formation by the CVD method, the precursor is required to be vaporizable. To date, many methods have been reported in which various organosilicon compounds are used as precursors and silicon-containing thin films with desired compositions and properties are deposited by the CVD method.

In the molecular design of silica thin film precursors for CVD, it is important that they have a high vapor pressure, can deposit a silica thin film at a good film-forming rate, and can express the desired functions and physical properties. Generally, monosilane compounds with one silicon atom, especially tetramethoxysilane and tetraethoxysilane, are used because of their ease of availability and high vapor pressure, but there is still much room for improvement in their film-forming rate. In addition, hydrogen-substituted silanes (hydrosilanes) in which hydrogen atoms are substituted on silicon atoms have smaller molecular weights and weaker intermolecular interactions than the corresponding alkoxy and alkyl compounds, and therefore can achieve high vapor pressures, but they are often unstable against oxygen in the air, which can cause safety problems. Increasing the number of silicon atoms in the precursor (multinucleation) is expected to be effective in improving the film-forming rate, and at the same time, introducing hydrogen atoms onto the silicon atoms of the precursor is considered effective in avoiding low vapor pressures due to increased molecular weights.

Non-Patent Document 1 reports a silica barrier film deposited on a polymer film using hexamethyldisiloxane as a precursor by the CVD method. However, thin films using hexamethyldisiloxane as a precursor tend to have residual carbon and are easily discolored. In Patent Document 1, a SiCHO film is deposited by the CVD method using 1,3-dimethyl-1,3-diethoxydisiloxane, but the resulting thin film is a low dielectric constant film and the water vapor barrier property of the film is not described. Patent Document 2 discloses the production of a polyethylene naphthalate (PEN) film with a silica gas barrier layer formed by plasma-assisted chemical vapor deposition (PECVD) using tetraethoxysilane and oxygen as raw materials. Although the water vapor barrier property (WVTR) of this thin film is 1.7×10 ⁻³ g/m ² ·day, which is sufficient water vapor barrier property, the film formation speed is low at 67 nm/min, and there is room for improvement in the film formation speed. Patent Document 3 discloses a method for forming a gas barrier film by a PECVD method using an alkylhydrodisiloxane compound at a film formation rate of 257 nm/min, and describes a gas barrier film that exhibits a low WVTR value of 4.0 × 10 ^-3 g/m ² ·day in a thick single-layer film with a thickness of 2,570 nm.

International Publication No. 2016/144960 JP 2016-176091 A Patent No. 6007662

Lin Han et al., Journal of the Electrochemical Society, Vol. 156, pp. H106-H114, 2009

The objective of the present invention is to provide a silicon-based compound that exhibits high vaporization characteristics and is useful as a precursor for producing a silica thin film at a good deposition rate in a CVD method, and a method for producing the same.

As a result of extensive research aimed at solving the above problems, the inventors discovered that a dihydrodisiloxane compound having one hydrogen atom, one alkyl group with a specific carbon number, and one alkoxy group on a silicon atom exhibits high vaporization properties and is useful as a precursor for producing a silica thin film at a good film formation rate in a CVD method, thus completing the present invention.

That is, the present invention comprises the following:
[1]
General formula (1)

(1)
(In the formula, ^R1 represents an alkyl group having 1 to 6 carbon atoms, and ^R2 represents an alkyl group having 1 to 3 carbon atoms. The sum of the carbon numbers of the alkyl groups represented by ^R1 and ^R2 is 4 or more and 9 or less.)
[2]
The dihydrodisiloxane compound according to [1], wherein in general formula (1), R ¹ is a methyl group, an ethyl group, or an isopropyl group.
[3]
The dihydrodisiloxane compound according to [1] or [2], wherein, in general formula (1), R ¹ is an isopropyl group and R ² is a methyl group.
[4]
General formula (2)

(2)
(wherein ^X1 represents a halogen atom, an alkoxy group having 1 to 3 carbon atoms, or a dialkylamino group having 2 to 12 carbon atoms; ^R1 represents an alkyl group having 1 to 6 carbon atoms, ^R2 represents an alkyl group having 1 to 3 carbon atoms, and the sum of the carbon numbers of the alkyl groups represented by ^R1 and ^R2 is 4 or more and 9 or less) is reacted with water or a metal oxide,

(1)
(wherein R ¹ and R ² are as defined above)
[5]
General formula (3)

(3)
(wherein ^X2 represents a halogen atom, ^{and R1} represents an alkyl group having 1 to 6 carbon atoms),
(R ² O) _n M (4)
( ^R2 represents an alkyl group having 1 to 3 carbon atoms; M represents a hydrogen atom, an alkali metal, or an alkaline earth metal; and n is 1 or 2, and is 1 when M is a hydrogen atom or an alkali metal, and is 2 when M is an alkaline earth metal),

(1)
(wherein ^R1 and ^R2 are as defined above, and the sum of the carbon numbers of the alkyl groups represented by ^R1 and ^R2 is 4 or more and 9 or less).

The dihydrodisiloxane compound (1) of the present invention exhibits high vaporization properties and is useful as a precursor for producing a silica thin film at a good film formation rate by the CVD method.

The present invention is described in detail below.

First, ^R1 and ^R2 in the general formulae (1), (2), (3) and (4) will be described.

R ¹ is an alkyl group having 1 to 6 carbon atoms, which may be linear, branched, or cyclic. Examples of the alkyl group include methyl, ethyl, propyl, isopropyl, cyclopropyl, butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, pentyl, cyclopentyl, 1-methylbutyl, 1-ethylpropyl, neopentyl, 2-methyl-2-butyl, 3-methyl-2-butyl, hexyl, 1-methylpentyl, 1-ethylbutyl, 2,3-dimethyl-2-butyl, and cyclohexyl. Among these, from the viewpoints of the production cost, stability against oxygen, and vapor pressure of the dihydrodisiloxane compound (1) of the present invention, methyl, ethyl, propyl, or isopropyl is preferred, methyl, ethyl, or isopropyl is more preferred, methyl or isopropyl is particularly preferred, and isopropyl is particularly preferred.

^R2 is an alkyl group having 1 to 3 carbon atoms, which may be linear, branched, or cyclic. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a cyclopropyl group. Among these, from the viewpoints of the production cost, the stability against oxygen, and the vapor pressure of the dihydrodisiloxane compound (1) of the present invention, a methyl group, an ethyl group, a propyl group, or an isopropyl group is preferred, a methyl group, an ethyl group, or an isopropyl group is more preferred, a methyl group or an isopropyl group is particularly preferred, and a methyl group is particularly preferred.

Next, the dihydrodisiloxane compound (1) of the present invention will be described. The dihydrodisiloxane compound (1) of the present invention is represented by the following general formula (1):

(1)
(In the formula, ^R1 represents an alkyl group having 1 to 6 carbon atoms, ^R2 represents an alkyl group having 1 to 3 carbon atoms, and the sum of the carbon numbers of the alkyl groups represented by ^R1 and ^R2 is 4 or more and 9 or less).

In the dihydrodisiloxane compound (1), if the sum of the carbon numbers of the alkyl groups represented by ^R1 and ^R2 exceeds 9, the molecular weight increases, resulting in a lower vapor pressure, making the compound difficult to vaporize and evaporate, making the compound unsuitable as a CVD material. Also, if the sum of the carbon numbers of the alkyl groups represented by ^R1 and ^R2 is 3 or less, the hydrogen atoms on the silicon atoms are easily oxidized by oxygen in the air, and high molecular weight silicon oxides produced by oxidation during storage or film formation may deteriorate the quality of the thin film or interfere with film formation.

The dihydrodisiloxane compound (1) represented by the general formula (1) includes three isomers, the (1R,3R) form, the (1R,3S) form, and the (1S,3S) form, depending on the stereochemistry of the silicon atoms at the 1st and 3rd positions. The (1R,3R) form and the (1S,3S) form are mutually enantiomeric. The dihydrodisiloxane compound (1) of the present invention may be a mixture of these isomers, or may contain one of the isomers predominantly. In this specification, there is no distinction between these isomers.

Specific examples of the dihydrodisiloxane compound (1) of the present invention represented by general formula (1) include the following compounds. Note that in this specification, Me, Et, Pr, i-Pr, Bu, i-Bu, sec-Bu, tert-Bu, Pen, and Hex represent methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, and hexyl, respectively.

Among these, (1-1-2), (1-2-1), (1-2-3), (1-4-1), (1-4-2), (1-7-1) or (1-8-1) are preferred, (1-1-2), (1-2-3), (1-4-1), (1-7-1) or (1-8-1) are more preferred, and (1-1-2) or (1-4-1) is especially preferred, in terms of the high vapor pressure of the dihydrodisiloxane compound (1) of the present invention, the stability against oxygen, the high water vapor barrier properties of the silica film after film formation, and the excellent economy.

Next, the method for producing the dihydrodisiloxane compound (1) of the present invention will be described.

First, X ¹ , X ² and M in the general formulae (2), (3) and (4) will be described.

^X1 is a halogen atom, an alkoxy group having 1 to 3 carbon atoms, or a dialkylamino group having 2 to 12 carbon atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, from the viewpoints of the production cost and stability of the dihydrodisiloxane compound (1) of the present invention, a fluorine atom, a chlorine atom, or a bromine atom is preferred, a chlorine atom or a bromine atom is more preferred, and a chlorine atom is particularly preferred. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propyloxy group, or an isopropyloxy group. Among these, from the viewpoints of the production cost, production yield, and ease of purification of the dihydrodisiloxane compound (1) of the present invention, a methoxy group, an ethoxy group, or an isopropyloxy group is preferred, and a methoxy group or an ethoxy group is more preferred.

In the dialkylamino group having 2 to 12 carbon atoms represented by X ¹ , the two alkyl groups on the nitrogen may be the same or different from each other. In addition, the amino group may be substituted with a linear alkyl group or a branched alkyl group, and the two alkyl groups may be linked to each other to form a ring containing nitrogen. Examples of the dialkylamino group include a dimethylamino group, a diethylamino group, a diisopropylamino group, a dibutylamino group, a piperidino group (N-piperidin-1-yl group), a pyrrolidino group (pyrrolidin-1-yl group), and a dihexylamino group. Among these, from the viewpoints of economy and safety in handling, a dimethylamino group, a diethylamino group, or a diisopropylamino group is preferred, and a dimethylamino group or a diethylamino group is more preferred.

^X2 is a halogen atom, and examples thereof include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, from the viewpoints of yield and economy, a fluorine atom, a chlorine atom, or a bromine atom is preferred, a chlorine atom or a bromine atom is more preferred, and a chlorine atom is particularly preferred.

M is a hydrogen atom, an alkali metal, or an alkaline earth metal, and examples of the alkali metal or alkaline earth metal include lithium, sodium, potassium, cesium, magnesium, calcium, strontium, and barium. Among these, lithium, sodium, potassium, magnesium, and calcium are preferred from the standpoint of yield and raw material cost, and sodium, potassium, and magnesium are more preferred.

The dihydrodisiloxane compound (1) of the present invention can be produced by either Production Method 1 (hereinafter referred to as Production Method 1 of the present invention) or Production Method 2 (hereinafter referred to as Production Method 2 of the present invention) described below.

The following describes Production Method 1 of the present invention. Production Method 1 of the present invention is a production method of the dihydrodisiloxane compound (1) of the present invention, which is produced by reacting a hydroalkoxysilane compound (2) represented by general formula (2) with water or a metal oxide.

(In the formula, R ¹ and R ² are the same as those in general formula (1), and X ¹ represents a halogen atom, an alkoxy group having 1 to 3 carbon atoms, or a dialkylamino group having 2 to 12 carbon atoms).

Examples of the hydroalkoxysilane compound (2) that can be used as a raw material in the manufacturing method 1 of the present invention include the following compounds.

Among these, from the viewpoints of raw material cost, yield and stability, compounds (2-1-2), (2-1-8), (2-2-1), (2-2-10), (2-4-1), (2-4-13), (2-7-13) and (2-8-13) are preferred, and compounds (2-1-8), (2-2-10), (2-4-13) and (2-8-13) are more preferred.

To obtain the hydroalkoxysilane compound (2), if a commercially available product is available, it may be obtained and used as is or after appropriate purification. As a method for producing the hydroalkoxysilane compound (2), various known synthesis methods can be adopted, and those skilled in the art can easily synthesize and use them. As long as it does not interfere with the production method 1 of the present invention, the production process of these hydroalkoxysilane compounds (2) may be included as a pre-step of the production method 1 of the present invention.

In Production Method 1 of the present invention, when ^X1 in the hydroalkoxysilane compound (2) is a halogen atom, the compound is produced by reacting water or a metal oxide with the alkoxyhydrosilane compound (2) (hereinafter referred to as Production Method 1-1).

The halogen represented by ^X1 may be any one of a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. From the viewpoints of economy and good yield of the precursor, a chlorine atom or a bromine atom is preferred, and a chlorine atom is more preferred.

When water is used in the manufacturing method 1-1 of the present invention (hereinafter referred to as manufacturing method 1-1-1), the dihydrodisiloxane compound (1) of the present invention can be produced in good yield by reacting 0.3 to 10 molar equivalents of water with 1 mole of the raw material hydroalkoxysilane compound (2). From the viewpoints of economy, production efficiency, and reaction yield, the equivalent of water is preferably an equivalent appropriately selected from the range of 0.4 to 0.7 molar equivalents. In addition, in order to accelerate the manufacturing reaction, a base such as an organic amine may be added. Examples of the organic amine include primary amines such as butylamine and hexylamine, secondary amines such as dimethylamine and diethylamine, tertiary amines such as triethylamine and diisopropylethylamine, aromatic amines such as aniline, and heterocyclic amines such as pyridine, quinoline, and piperidine. From the viewpoints of economy and yield, triethylamine, diisopropylethylamine, or pyridine is preferred, and triethylamine or pyridine is more preferred.

In the manufacturing method 1-1-1, the manufacturing may be carried out in an organic solvent. Examples of organic solvents that can be used include hydrocarbon solvents such as hexane, heptane, toluene, xylene, and benzene; ether solvents such as diethyl ether, dioxane, tetrahydrofuran, diisopropyl ether, methyl-tert-butyl ether, and cyclopentyl methyl ether; and halogenated hydrocarbon solvents such as dichloromethane, chloroform, and carbon tetrachloride. From the standpoint of yield and economy, diethyl ether, tetrahydrofuran, dioxane, or cyclopentyl methyl ether is preferred, and diethyl ether or tetrahydrofuran is more preferred. These organic solvents may be used alone or in combination of two or more solvents in an appropriate ratio.

There is no particular restriction on the order of mixing the hydroalkoxysilane compound (2) and water when carrying out production method 1-1-1. For example, a method in which the hydroalkoxysilane compound (2) is mixed in an organic solvent and water (or a metal oxide) is added thereto is preferred from the standpoint of yield and safety.

When carrying out manufacturing method 1-1-1, it is preferable to carry out the method under an inert gas atmosphere in terms of good yield. Specific examples of the inert gas include nitrogen, helium, neon, argon, etc. Nitrogen or argon is preferable in terms of low cost.

In manufacturing method 1-1-1, there are no limitations on the reaction temperature and reaction time, and general conditions used by those skilled in the art when carrying out a hydrolysis reaction of a functional silane can be used. As a specific example, dihydrodisiloxane compound (1) can be produced in good yield by selecting a reaction temperature appropriately selected from the temperature range of -80°C to 300°C and a reaction time appropriately selected from the range of 1 minute to 120 hours.

When a metal oxide is used in Production Method 1-1 (hereinafter referred to as Production Method 1-1-2), examples of the metal oxide include zinc oxide, iron oxide, cobalt oxide, copper (I) oxide, copper (II) oxide, rhenium oxide, and silver oxide. It is preferable to use zinc oxide because of its high yield.

In manufacturing method 1-1-2, there is no particular restriction on the molar equivalent of the metal oxide, and the compound can be produced in good yield at a molar ratio within an appropriately selected range of, for example, 0.5 to 20 molar equivalents of metal in the metal oxide per 1 molar equivalent of halogen atoms in the hydroalkoxysilane compound (2).

In the manufacturing method 1-1-2, the manufacturing may be carried out in an organic solvent. Examples of the organic solvent include ether solvents such as diethyl ether, tert-butyl methyl ether, 1,4-dioxane, 1,2-dimethoxyethane, tetrahydrofuran, cyclopentyl methyl ether, and diglyme; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and carboxylic acid ester solvents such as ethyl acetate and methyl acetate. Of these, tetrahydrofuran, ethyl acetate, and methyl acetate are preferred from the standpoints of economy, safety, and yield.

In manufacturing method 1-1-2, it is preferable to carry out the method under an inert gas atmosphere in terms of good yield. Specific examples of the inert gas include nitrogen, helium, neon, and argon. Nitrogen or argon is preferable in terms of low cost.

In manufacturing method 1-1-2, there are no limitations on the reaction temperature and reaction time, and general conditions used by those skilled in the art when manufacturing functional disiloxanes can be used. As a specific example, dihydrodisiloxane compound (1) can be produced in good yield by selecting a reaction temperature appropriately selected from the temperature range of -10°C to 300°C and a reaction time appropriately selected from the range of 1 minute to 120 hours.

In the production method 1 of the present invention, when ^X1 of the hydroalkoxysilane compound (2) is an alkoxy group (hereinafter referred to as production method 1-2), water is reacted with the hydroalkoxysilane compound (2) to produce the dihydrodisiloxane compound (1) of the present invention. Examples of the alkoxy group represented by ^X1 include a methoxy group, an ethoxy group, a propyloxy group, and an isopropyloxy group. From the viewpoints of economy and good yield of the precursor, a methoxy group, an ethoxy group, and an isopropyloxy group are preferred, and a methoxy group or an ethoxy group are more preferred. Furthermore, when ^X1 is an alkoxy group, it is preferred from the viewpoint of yield that ^X1 is the same as the alkoxy group represented by ^OR2.

In manufacturing method 1-2, dihydrodisiloxane compounds can be produced in good yields by reacting 0.3 to 10 molar equivalents of water with 1 molar equivalent of the raw material hydroalkoxysilane compound (2). From the standpoint of economy, production efficiency, and reaction yield, it is preferable that the water equivalent is appropriately selected from the range of 0.4 to 0.7 molar equivalents. In addition, an acidic or basic catalyst may be used to accelerate the reaction.

In the production method 1 of the present invention, when X ¹ of the hydroalkoxysilane compound (2) is a dialkylamino group (hereinafter referred to as production method 1-3), the dihydrodisiloxane compound (1) of the present invention is produced by reacting the hydroalkoxysilane compound (2) with water. Examples of the dialkylamino group include dimethylamino, diethylamino, diisopropylamino, dibutylamino, piperidino (N-piperidin-1-yl), pyrrolidino (pyrrolidin-1-yl), and dihexylamino. Of these, from the viewpoints of economy and safety in handling, dimethylamino, diethylamino, and diisopropylamino are preferred, and diethylamino and diisopropylamino are more preferred. When X ¹ is a dialkylamino group, the dihydrodisiloxane compound (1) of the present invention can be produced in good yield by reacting 0.3 to 10 molar equivalents of water with 1 molar equivalent of the hydroalkoxysilane compound (2) as the raw material. From the viewpoints of economy, production efficiency and reaction yield, the amount of water is preferably an amount appropriately selected from the range of 0.4 to 0.7 molar equivalents.

In the manufacturing method 1-3, the order of mixing the hydroalkoxysilane compound (2) and water is not particularly limited, but from the viewpoints of yield and safety, for example, a method in which the hydroalkoxysilane compound (2) is mixed in an organic solvent and then water (or a metal oxide) is added thereto is preferred.

In manufacturing methods 1-2 and 1-3, similar to manufacturing methods 1-1-1 and 1-1-2, production can be carried out using an organic solvent under an inert gas atmosphere, and the temperature and time can also be similar.

The dihydrodisiloxane compound (1) produced by the production method 1 of the present invention can be purified by a person skilled in the art by appropriately selecting and using a general purification method used when purifying alkoxylated silanes. Specific purification methods include filtration, concentration, extraction, washing, drying, centrifugation, distillation, and chromatographic separation. Since purity is important for CVD materials, it is preferable to include a purification step using distillation.

Next, the production method 2 of the present invention will be described. The production method 2 of the present invention comprises reacting a dihalodisiloxane compound represented by the general formula (3) with a compound represented by the general formula (4)
(R ² O) _n M (4)
( ^R2 is as defined above. M represents a hydrogen atom, an alkali metal, or an alkaline earth metal. n is 1 or 2; when M is a hydrogen atom or an alkali metal, n is 1, and when M is an alkaline earth metal, n is 2.) to produce the dihydrodisiloxane compound (1) of the present invention.

(In the formula, ^R1 represents an alkyl group having 1 to 6 carbon atoms, ^X2 represents a halogen atom, and ^R2 represents an alkyl group having 1 to 3 carbon atoms.)
The alcohol that can be used in Production Method 2 is an aliphatic alcohol having 1 to 3 carbon atoms. Examples of the alcohol include methanol, ethanol, propyl alcohol, isopropyl alcohol, etc. Among these, in terms of yield and raw material cost, methanol, ethanol, or isopropyl alcohol is preferred, and methanol or ethanol is more preferred. The alcohol can be a commercially available product and used as is, or after appropriate purification.

Metal alkoxides that can be used in manufacturing method 2 are alkali metal salts or alkaline earth metal salts of aliphatic alcohols having 1 to 3 carbon atoms, and examples of the metal alkoxides include lithium methoxide, lithium ethoxide, lithium isopropyl oxide, sodium methoxide, sodium ethoxide, sodium isopropyl oxide, potassium methoxide, potassium ethoxide, potassium isopropyl oxide, cesium methoxide, cesium ethoxide, cesium isopropyl oxide, magnesium methoxide, magnesium ethoxide, magnesium isopropyl oxide, etc. Among these, sodium methoxide, sodium ethoxide, sodium propyl oxide, potassium methoxide, potassium ethoxide, magnesium methoxide, magnesium ethoxide, magnesium isopropyl oxide are preferred from the standpoint of yield and raw material cost, and sodium methoxide, sodium ethoxide, and sodium propyl oxide are more preferred.

The metal alkoxide can be used as it is in the form of a commercially available powder, or an alcohol solution of the metal alkoxide can be purchased and used, or one prepared by reacting an alkali metal with an alcohol can be used, and these can be easily used by those skilled in the art.

The amount of alcohol used in Production Method 2 of the present invention is preferably an amount appropriately selected from 1.6 to 200 molar equivalents relative to the molar equivalent of dihalodisiloxane compound (3), more preferably an amount appropriately selected from 2 to 20 molar equivalents, and even more preferably an amount appropriately selected from 2 to 4 molar equivalents.

The amount of metal alkoxide used in Production Method 2 of the present invention is preferably an amount appropriately selected from 1.6 to 200 molar equivalents relative to the molar equivalent of dihalodisiloxane compound (3), more preferably an amount appropriately selected from 2 to 20 molar equivalents, and even more preferably an amount appropriately selected from 2 to 4 molar equivalents.

Examples of the dihalodisiloxane compound (3) that can be used as a raw material in the manufacturing method 2 of the present invention include the following compounds.

Among these, (3-1-1), (3-2-1) or (3-4-1) is preferred from the viewpoint of yield and economy, and (3-1-1) is more preferred.

The production method 2 of the present invention is preferably carried out in an organic solvent. Examples of the organic solvent include ether solvents such as diethyl ether, tert-butyl methyl ether, 1,4-dioxane, 1,2-dimethoxyethane, tetrahydrofuran, cyclopentyl methyl ether, and diglyme, and hydrocarbon solvents such as pentane, hexane, heptane, octane, benzene, and toluene. Among these, diethyl ether, tetrahydrofuran, and cyclopentyl methyl ether are preferred from the standpoints of economy, safety, and yield. In addition, the alcohol used as a raw material may be used in an equivalent amount or more to serve as both an organic solvent and an organic solvent.

When the production method 2 of the present invention is carried out using an alcohol, an organic amine compound may be used in combination. The organic amine compound reacts with hydrogen halide produced as a by-product in the reaction, and has the effect of increasing the reaction yield and promoting the reaction. Examples of the organic amine compound include trimethylamine, triethylamine, ethyldiisopropylamine, pyridine, quinoline, etc., and triethylamine or pyridine is preferred. The amount of the organic amine compound used is preferably a molar equivalent appropriately selected from 0.8 to 10 molar equivalents relative to 1 molar equivalent of the number of halogen atoms on the silicon atoms of the dihalodisiloxane compound (3), more preferably a molar equivalent appropriately selected from 1.0 to 2.0 molar equivalents, and even more preferably a molar equivalent appropriately selected from 1.0 to 1.2 molar equivalents.

When carrying out Production Method 2, it is preferable to carry out the process under an inert gas atmosphere in terms of good yield. Specific examples of the inert gas include nitrogen, helium, neon, argon, etc. Nitrogen or argon is preferable in terms of low cost. The reaction pressure is preferably selected from the range of 0.1 to 1000 atmospheres, more preferably 0.1 to 10 atmospheres, and most preferably 1 atmosphere.

There is no particular limitation on the reaction temperature in Production Method 2 of the present invention, and in terms of yield, safety, and operability, it is preferable to carry out the reaction at a temperature appropriately selected from the range of -80 to 200°C, more preferably from the range of -20°C to 50°C, and especially preferably at room temperature. The reaction time is appropriately determined by checking the progress of the reaction by instrumental analysis, and dihydrodisiloxane compound (1) can be produced in good yield by carrying out the reaction for a reaction time appropriately selected from the range of 1 minute to 200 hours.

The dihydrodisiloxane compound (1) of the present invention produced by Production Method 2 can be purified by a person skilled in the art by appropriately selecting a general purification method used when purifying alkoxysilanes. Specific purification methods include filtration, concentration, extraction, washing, drying, centrifugation, distillation, etc. In particular, since purity is important for CVD materials, it is preferable to include a purification step using distillation.

When the dihydrodisiloxane compound (1) of the present invention is used as a precursor for a CVD process, specific means for the CVD process include general means that are commonly used by those skilled in the art to prepare a silica thin film by a CVD method. When producing a silica thin film by a CVD method, the dihydrodisiloxane compound (1) of the present invention is vaporized and supplied as a gas to a reaction chamber. Examples of methods for vaporizing the dihydrodisiloxane compound (1) of the present invention include a bubbling method and a liquid injection method. The bubbling method is a method in which the dihydrodisiloxane compound (1) of the present invention is placed in a material container kept at a constant temperature by a thermostatic bath, and a carrier gas such as helium, neon, argon, krypton, xenon, or nitrogen is blown in to vaporize the dihydrodisiloxane compound (1) of the present invention. The liquid injection method is a method in which the dihydrodisiloxane compound (1) of the present invention is sent in a liquid state to a vaporizer and vaporized by heating in the vaporizer. In the liquid injection method, the dihydrodisiloxane compound (1) of the present invention can also be used as a solution by dissolving it in a solvent.

By decomposing the dihydrodisiloxane compound (1) of the present invention supplied as a gas to a reaction chamber, a thin silica film can be produced on a substrate. Examples of methods for decomposing the dihydrodisiloxane compound (1) of the present invention include a thermal method, a method using plasma or light, and a method in which a reactive gas is fed into a reaction chamber to cause a chemical reaction. By using these methods alone or in combination, the dihydrodisiloxane compound (1) of the present invention can be decomposed to produce a thin silica film.

The dihydrodisiloxane compound (1) of the present invention has both hydrogen atoms and alkoxy groups, which are different reactive functional groups, on the silicon atom, and therefore can be used as a raw material for silicon-containing materials such as various functional siloxane materials and organic silsesquioxane materials, or as a reducing agent or protecting group in organic synthesis reactions.

The present invention will be explained in more detail below with reference to examples and comparative examples, but the scope of the present invention should not be interpreted as being limited to the specific examples shown below.

All the preparations described in the examples were carried out under an argon atmosphere. Instrumental analysis, ¹ H-NMR (proton nuclear magnetic resonance spectrum), ¹³ C-NMR (carbon-13 nuclear magnetic resonance spectrum) and ²⁹ Si-NMR (silicon-29 nuclear magnetic resonance spectrum) were performed using an Avance series Ascend 400 nuclear magnetic resonance spectrometer from Bruker. Deuterated chloroform was used as the nuclear magnetic resonance spectrum measurement solvent, and chemical shifts were determined using tetramethylsilane as an internal standard. Infrared spectrum was measured using an FT-720 spectrophotometer from Horiba Ltd. and a DuraSamplIRII (reflective type) measurement cell from SensIRtechnologies. Mass spectrometry and gas chromatography measurements were performed using a Shimadzu Corporation GCMS-QP2010 gas chromatography mass spectrometer and an Agilent Technologies DB-5MS capillary column.

The 1,3-dichloro-1,3-dimethyldisiloxane used in the production was synthesized according to the method described in the literature (U.S. Patent No. 2,519,881). tert-Butyldichlorosilane (reagent manufactured by Sigma-Aldrich Japan Co., Ltd.), trichlorosilane (reagent manufactured by Tokyo Chemical Industry Co., Ltd.), 2-chloropropane (reagent manufactured by Tokyo Chemical Industry Co., Ltd.), 2-chlorobutane (reagent manufactured by Tokyo Chemical Industry Co., Ltd.), magnesium (reagent manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.), dehydrated diethyl ether (reagent manufactured by Kanto Chemical Co., Ltd.), dehydrated tetrahydrofuran (hereinafter abbreviated as dehydrated THF) (reagent manufactured by Kanto Chemical Co., Ltd.), dehydrated hexane (reagent manufactured by Kanto Chemical Co., Ltd.), dehydrated methanol (reagent manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.), isopropyl alcohol (reagent manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.), pyridine (reagent manufactured by Kanto Chemical Co., Ltd.), triethylamine (reagent manufactured by Kanto Chemical Co., Ltd.), and diethylamine (reagent manufactured by Kanto Chemical Co., Ltd.) were purchased commercially and used as they were.

(Example 1) Synthesis of 1,3-dimethyl-1,3-di(isopropyloxy)disiloxane (example compound number (1-1-2))

A 200 mL three-neck flask equipped with a magnetic stirrer, a dropping funnel, a Dimroth condenser, and a three-way cock was purged with argon, and 60 mL of dehydrated diethyl ether, 14.3 g (181 mmol) of dehydrated pyridine, and 15.0 g (85.6 mmol) of 1,3-dichloro-1,3-dimethyldisiloxane (exemplary compound number (3-1-1)) were placed in the flask. The vessel was cooled to 0° C., and a solution of 10.3 g (171 mmol) of 2-propanol in 40 mL of dehydrated diethyl ether was added dropwise from the dropping funnel over a period of 2 hours, followed by stirring at room temperature for 16 hours and heating to reflux for an additional 2 hours. Under an argon atmosphere, the precipitate was filtered off using a sintered glass filter. The filtrate was concentrated to remove low boiling point components, and the resulting crude product was distilled under reduced pressure (boiling point 76° C./6.5 kPa) to obtain 14.5 g (yield 76%) of 1,3-dimethyl-1,3-di(isopropyloxy)disiloxane (exemplary compound number (1-1-2)) as a colorless liquid.
Mass spectrum (electron impact ionization, 70 eV), m/z (%): 221 ([MH] ⁺ , 7), 179 ([M-Pr] ⁺ , 23), 137 (100); ¹ H-NMR (400 MHz, CDCl ₃ ) δ (ppm): 0.20 (d, 6H, J = 1.6Hz), 1.22 (dd, 12H, J = 2.5, 6.1Hz), 4.16 (m, 2H), 4.69 (d, 2H, J = 1.3Hz); ^13C -NMR (101MHz, CDCl ₃ ) δ (ppm): -0.61, -0.59, 25.38, 25.51, 66.09; ²⁹ Si-NMR (79 MHz, CDCl ₃ ) δ (ppm): -28.19, -28.16; Infrared spectrum (neat, cm ^-1 ): 2972, 2933, 2877, 2139, 1456, 1383, 1369, 1257, 1174, 1124, 1070, 1030, 903, 874, 860, 762, 667.

(Example 2) Production of 1,3-diisopropyl-1,3-dimethoxydisiloxane (example compound number (1-4-1))

9.40 g (387 mmol) of magnesium metal cuttings were placed in a 500 mL three-neck flask equipped with a magnetic stirrer, dropping funnel, Dimroth condenser, and three-way stopcock, and the atmosphere inside the apparatus was replaced with argon. 10 mL of dehydrated THF was placed in the three-neck flask, and 0.1 mL of 1,2-dibromoethane was added to activate the magnesium. Next, a solution of 29.9 g (381 mmol) of 2-chloropropane in 190 mL of dehydrated THF was dropped from the dropping funnel over 1.5 hours, and after the dropwise addition was completed, the mixture was stirred at room temperature for a further 1.5 hours to prepare an isopropyl magnesium chloride solution.

Separately, a 1000 mL three-neck flask equipped with a magnetic stirrer, dropping funnel, Dimroth condenser, and three-way cock was purged with argon, and 50.9 g (376 mmol) of trichlorosilane and 300 mL of dehydrated THF were placed in the reaction vessel. The reaction vessel was cooled to -10°C, and the previously prepared isopropyl magnesium chloride solution was added dropwise from the dropping funnel over a period of 4.5 hours. After the addition was complete, the reaction vessel was returned to room temperature and stirred for 72 hours to prepare an isopropyldichlorosilane solution.

The above isopropyldichlorosilane solution was cooled to 0°C, and a mixture of 77.5 g (0.765 mol) of triethylamine and 27.1 g (0.376 mol) of diethylamine was added dropwise from the dropping funnel over 1 hour, followed by stirring for an additional 2 hours. Next, a solution of 12.1 g (0.376 mol) of methanol in 40 mL of dehydrated THF was added dropwise from the dropping funnel to this mixture at 0°C over 2 hours. After the addition was completed, the mixture was stirred at room temperature for 16 hours to prepare a solution of (diethylamino)isopropylmethoxysilane (exemplified compound number (2-4-13)).

Next, 3.99 g (0.188 mol) of distilled water was slowly added to the three-neck flask with stirring using a syringe, and the mixture was then heated to reflux for 2 hours. The solution was concentrated to about half its original volume under reduced pressure, 300 mL of dehydrated hexane was added thereto, and the solids were filtered off using a sintered glass filter under an argon atmosphere. This was concentrated again, diluted with dehydrated hexane, and the solids were filtered off again using a sintered glass filter. The crude product obtained after concentration was distilled under reduced pressure (boiling point 86°C/4.8 kPa) to obtain 22.6 g (54% yield from trichlorosilane) of 1,3-diisopropyl-1,3-dimethoxydisiloxane (exemplified compound number (1-4-1)) as a colorless liquid. This compound is a mixture of molecules having the stereochemistry of (1R,3R) and (1S,3S) based on the stereoisomerism on silicon, and the nuclear magnetic resonance spectrum based on the presence of two diastereomeric isomers was observed.
Mass spectrum (electron impact ionization, 70 eV), m/z (%): 179 ([M-Pr] ⁺ , 100), 151 (72), 121 (65); ¹ H-NMR (400 MHz, CDCl ₃ ) δ (ppm): 0.842 to 0.932 (m, 2H), 1.01 (dd, 12H, J = 7.1, 1.3Hz), 3.57 (s, 6H), 4.44 (d, 2H, J = 0.68Hz); ^13C -NMR (101MHz, CDCl ₃ ) δ (ppm): 13.49, 15.67, 51.28; ²⁹ Si-NMR (79 MHz, CDCl ₃ ) δ (ppm): -21.90, -21.87; Infrared spectrum (neat, cm ^-1 ): 2945, 2897, 2868, 2837, 2131, 1464, 1385, 1246, 1190, 1165, 1088, 1057, 1001, 922, 881, 825, 766, 683, 661, 648.

(Synthesis Example 1) Preparation of sec-butyldichlorosilane

13.4 g (552 mmol) of magnesium metal cuttings were placed in a 500 mL three-neck flask equipped with a magnetic stirrer, dropping funnel, Dimroth condenser, and three-way stopcock, and the atmosphere inside the apparatus was replaced with argon. 20 mL of dehydrated diethyl ether was placed in the three-neck flask, and 0.1 mL of 1,2-dibromoethane was added to activate the magnesium. Next, 50.2 g (0.543 mol) of 2-chlorobutane in 700 mL of dehydrated diethyl ether was dropped from the dropping funnel over a period of 2 hours while maintaining reflux, and after the dropping was completed, the mixture was stirred at room temperature for 1.5 hours to prepare a sec-butylmagnesium chloride solution.

Separately, a 1000mL three-neck flask equipped with a magnetic stirrer, a dropping funnel, a Dimroth condenser and a three-way cock was replaced with argon, and 66.6g (492mmol) of trichlorosilane and 400mL of dehydrated diethyl ether were placed in the reaction vessel. The solution was cooled to -10°C, and the previously prepared sec-butyl magnesium chloride solution was dropped from the dropping funnel over 3.5 hours. After the dropwise addition was completed, the reaction vessel was returned to room temperature and stirred for 18 hours. 150mL of dehydrated diethyl ether and 300mL of hexane were added to the reaction mixture, and the solid precipitate was filtered out using a sintered glass filter under an argon atmosphere. The solution was concentrated and then distilled (boiling point 123°C) at normal pressure to obtain 45.2g (yield 58.5%) of sec-butyldichlorosilane as a colorless liquid.
¹ H-NMR (400 MHz, CDCl ₃ ) δ (ppm): 1.03 (t, 3 H, J = 7.4 Hz), 1.11-1.21 (m, 4 H), 1.36-1.47 (m, 1 H); ¹³ C-NMR (101 MHz, CDCl ₃ ) δ (ppm): 12.06, 12.72, 23.31, 25.72; ²⁹ Si-NMR (79 MHz, CDCl ₃ ) δ (ppm): 13.00.

(Example 3) Synthesis of 1,3-di-sec-butyl-1,3-dimethoxydisiloxane (example compound number (1-7-1))

A 300 mL three-neck flask equipped with a dropping funnel, a Dimroth condenser, a magnetic stirrer, and a three-way stopcock was purged with argon. 120 mL of dehydrated THF and 9.98 g (63.5 mmol) of sec-butyldichlorosilane obtained in Synthesis Example 1 were placed in the three-neck flask. The reaction vessel was cooled to -10°C, and a mixture of 10.0 g (0.127 mol) of pyridine and 4.66 g (63.7 mmol) of diethylamine was added dropwise from the dropping funnel over 1.5 hours, then the temperature was returned to room temperature and stirred for 2 hours to prepare a solution of sec-butylchloro(diethylamino)silane.

The reaction vessel was cooled again to -10°C, and a solution of 2.08 g (64.8 mmol) of methanol in 10 mL of dehydrated THF was added dropwise from the dropping funnel over a period of 1 hour. After the dropping was completed, the mixture was stirred at room temperature for 30 minutes and then heated under reflux for an additional 2 hours to prepare a solution of sec-butyl(diethylamino)methoxysilane (exemplified compound number (2-7-13)).

The mixture was returned to room temperature, 0.575 g (31.9 mmol) of distilled water was added via syringe, and the mixture was stirred at room temperature for 16 hours, and then heated to reflux for 1 hour. The solution was concentrated under reduced pressure until the volume was reduced to about half, and filtered under an argon atmosphere using a Schlenk tube with a glass filter and lined with Celite. The filtrate was concentrated again under reduced pressure, and the resulting crude product was distilled under reduced pressure (boiling point 110°C/3.6 kPa) to obtain 34.3 g (yield from sec-butyldichlorosilane: 47.1%) of 1,3-di-sec-butyl-1,3-dimethoxydisiloxane (exemplified compound number (1-7-1)) as a colorless liquid. This compound is a mixture of molecules with stereochemistry of (1R,3R) and (1S,3S) based on the stereoisomerism on silicon, and (1R,3S), and a nuclear magnetic resonance spectrum based on the presence of two diastereomeric isomers was observed.

Mass spectrum (electron impact ionization, 70 eV), m/z (%): 193 ([M-Bu] ⁺ , 53), 151 (25), 137 (100); ¹ H-NMR (400 MHz, CDCl ₃ ) δ (ppm): 0.675 to 0.766 (m, 2H), 0.95 to 1.00 (m, 12H), 1.23 to 1.34 (m, 2H), 1.54 to 1.65 (m, 2H), 3.57 (s, 6H), 4.49 (s, 2H); ¹³ C-NMR (101MHz, _CDCl3 ) δ (ppm): 12.43, 12.53, 13.07, 13.10, 21.31, 21.35, 23.69, 23.77, 51.32, 51.33; ²⁹ Si-NMR (79 MHz, CDCl ₃ ) δ (ppm): -22.26, -22.20, -22.15; Infrared spectrum (neat, cm ^-1 ): 2960, 2933, 2871, 2856, 2837, 2127, 1458, 1379, 1338, 1296, 1261, 1211, 1190, 1161, 1088, 1066, 1032, 1001, 968, 953, 931, 829, 764, 706, 667.

(Example 4) Synthesis of 1,3-di(tert-butyl)-1,3-dimethoxydisiloxane (example compound number (1-8-1))

A 200mL three-neck flask equipped with a magnetic stirrer, a dropping funnel, a Dimroth condenser and a three-way cock was replaced with argon, and 5.22g (33.2mmol) of tert-butyldichlorosilane, 5.30g (67.1mmol) of dehydrated pyridine and 40mL of dehydrated THF were placed in the flask. The flask was cooled to -10°C, and a solution of 2.43g (33.2mol) of diethylamine in 30mL of THF was dropped from the dropping funnel over 30 minutes, and then stirred at room temperature for 16 hours. The reaction mixture was then heated to reflux for 30 minutes. The reaction vessel was cooled again to -10°C, and a solution of 1.06g (33.3mmol) of methanol in 20mL of THF was dropped from the dropping funnel over 30 minutes. After the dropwise addition was completed, the reaction mixture was heated to reflux for 1 hour. After cooling the reaction vessel to -10°C again, a solution of 0.301g (16.7mmol) of distilled water in 20mL of THF was added dropwise from the dropping funnel over 30 minutes. After completion of the dropwise addition, the reaction mixture was heated to reflux for 1 hour. Under reduced pressure, the solution was concentrated until the liquid volume was reduced to about half, and the solid matter was filtered off using a sintered glass filter under an argon atmosphere. The filtrate was concentrated, and the obtained crude product was distilled under reduced pressure (distillation temperature 95°C/6.0kPa) using a Kugelrohr distillation apparatus, to obtain 1.67g of 1,3-di(tert-butyl)-1,3-dimethoxydisiloxane (exemplified compound number (1-8-1)) as a colorless liquid (yield from tert-butyldichlorosilane: 40.0%). This compound is a mixture of molecules having stereochemistry of (1R,3R) and (1S,3S) on silicon, as well as (1R,3S), and the nuclear magnetic resonance spectrum based on the existence of two diastereoisomers was observed.
Mass spectrum (electron impact ionization, 70 eV), m/z (%): 249 ([M-H] ⁺ , 0.3), 219 ([M-OMe] ⁺ , 0.2), 193 ([M-Bu] ⁺ , 100); ¹ H-NMR (400 MHz, CDCl ₃ ) δ (ppm): 0.941 (s, 18H), 3.59 (s, 6H), 4.39 (s, Si-H of one geometric isomer), 4.49 (s, Si-H of the other geometric isomer); ¹³ C-NMR (101 MHz, CDCl ₃ ) δ (ppm): 17.83, 17.84, 24.71, 51.61, 51.64; ²⁹ Si-NMR (79 MHz, CDCl ₃ ) δ (ppm): -22.31, -22.26, -22.15; Infrared spectrum (neat, cm ^-1 ): 2954, 2931, 2900, 2860, 2837, 2125, 1473, 1464, 1390, 1363, 1227, 1190, 1074, 1005, 941, 883, 827, 762, 702.

(Evaluation Example 1) Film formation using 1,3-diisopropyl-1,3-dimethoxydisiloxane (compound (1-4-1)) Using 1,3-diisopropyl-1,3-dimethoxydisiloxane (compound (1-4-1)), together with oxygen, a silicon oxide film was formed on a PEN film by PECVD. The supply flow rate of 1,3-diisopropyl-1,3-dimethoxydisiloxane (compound (1-4-1)) was 13 sccm, the oxygen supply flow rate was 90 sccm, the film formation chamber pressure was 40 Pa, and the power of the high frequency power source (RF power source) having a power frequency of 13.56 MHz was 900 W, and film formation was performed for 2 minutes. In addition, the ratio (Y/X) of the supply flow rate of oxygen to the supply flow rate of 1,3-diisopropyl-1,3-dimethoxydisiloxane (compound (1-4-1)) was 6.9.

The thickness of the obtained silicon oxide film was 306 nm. The film formation rate was 153 nm/min. The film had a composition of Si=33 atom %, O=67 atom %, and a carbon concentration of less than 1.0 atom %. The WVTR was 6.4×10 ⁻³ g/m ² ·day.

The visible light transmittance of the laminated film consisting of silicon oxide film and PEN film was 86.8%.

When 1,3-diisopropyl-1,3-dimethoxydisiloxane (compound (1-4-1)) was used to form a film together with oxygen by the PECVD method, even though the silicon oxide film was thin at 300 nm, it exhibited high gas barrier performance with a WVTR of the order of ¹⁰ g/ ^m2 ·day, and the film formation speed was also high at 100 nm/min or more, making it suitable as a gas barrier film.

(Comparative Evaluation Example 1) Film formation using tert-butyltriethoxysilane K. Lin, R. J. Wiles, C. B. Kelly, G. H. M. Davies, G. A. Molander, ACS Catalysis, 2017, Vol. 7, pp. 5129-5133. Using tert-butyltriethoxysilane synthesized with reference to the method described in, a silicon oxide film was formed on a PEN film by a PECVD method together with oxygen. The supply flow rate of tert-butyltriethoxysilane was 80 sccm, the oxygen supply flow rate was 2100 sccm, the film formation chamber pressure was 8 Pa, and the power of the high frequency power source (RF power source) with a power frequency of 13.56 MHz was 1000 W, and the film formation was performed for 14 minutes. The ratio Y/X of the supply flow rate of oxygen to the supply flow rate of tert-butyltriethoxysilane was 26.3.

The thickness of the obtained silicon oxide film was 800 nm. The composition of the film was Si=33 atom %, O=67 atom %, and the carbon concentration was less than 1.0 atom %. The WVTR value was 2.0×10 ⁻⁴ g/m ² ·day.

The visible light transmittance of the laminated film consisting of silicon oxide film and PEN film was 88.2%.

Using tert-butyltriethoxysilane and oxygen, a silicon oxide film was formed on a PEN film by the PECVD method. The supply flow rate of tert-butyltriethoxysilane was 80 sccm, the oxygen supply flow rate was 2100 sccm, the deposition chamber pressure was 8 Pa, and the power of the high frequency power source (RF power source) with a power frequency of 13.56 MHz was 1000 W. Film formation was performed for 7 minutes. The ratio Y/X of the supply flow rate of oxygen to the supply flow rate of tert-butyltriethoxysilane was 26.3.

The thickness of the obtained silicon oxide film was 400 nm. The film formation rate was 57 nm/min. The WVTR value was 4.3×10 ⁻⁴ g/m ² ·day. The visible light transmittance of the laminated film consisting of the silicon oxide film and the PEN film was 88.5%.

When a film is formed by PECVD using tert-butyltriethoxysilane together with oxygen, even a silicon oxide film with a thickness of 400 nm exhibits a WVTR of the order of 10 ⁻⁴ g/m ² ·day, which is less than 10 ⁻³ g/m ² ·day, but the film formation rate is low at 57 nm/min, resulting in poor productivity.

Comparative Example 2: Film formation using hexamethyldisiloxane Hexamethyldisiloxane was used together with oxygen to form a film on a PEN film by PECVD. The supply flow rate of hexamethyldisiloxane was 80 sccm, the supply flow rate of oxygen was 2100 sccm, the pressure in the film formation chamber was 6 Pa, and the power of the high frequency power source (RF power source) with a power frequency of 13.56 MHz was 1000 W, and film formation was performed for 2 minutes. The ratio Y/X of the supply flow rate of oxygen to the supply flow rate of hexamethyldisiloxane was 26.3.

The thickness of the obtained film was 200 nm. The film formation rate was 117 nm/min. The WVTR was 2.4×10 ⁻² g/m ² ·day, which was a high value.

When a film was formed by PECVD using hexamethyldisiloxane together with oxygen, in the case of a thin silicon oxide film having a thickness of 200 nm, the film formation rate was high at 117 nm/min, but the WVTR was high at 2.4×10 ⁻² g/m ² ·day.

Claims (5)

General formula (1)

(1)
(In the formula, ^R1 represents a linear or branched alkyl group having 2 to 6 carbon atoms, and ^R2 represents a linear or branched alkyl group having 1 to 3 carbon atoms. The sum of the carbon numbers of the alkyl groups represented by ^R1 and ^R2 is 4 or more and 9 or less. When R1 has 2 carbon atoms, R2 ^{has 2} carbon atoms. ) The dihydrodisiloxane compound according to claim 1, wherein in general formula (1), R ¹ is an ethyl group or an isopropyl group. 3. The dihydrodisiloxane compound according to claim 1, wherein in general formula (1), R ¹ is an isopropyl group and R ² is a methyl group. General formula (2)

(2)
(wherein ^X1 represents a halogen atom, an alkoxy group having 1 to 3 carbon atoms, or a dialkylamino group having 2 to 12 carbon atoms; ^R1 represents a linear or branched alkyl group having 2 to 6 carbon atoms, ^R2 represents a linear or branched alkyl group having 1 to 3 carbon atoms, and the sum of the carbon numbers of the alkyl groups represented by ^R1 and ^R2 is 4 to 9. When R1 has 2 carbon atoms, R2 ^{has 2} carbon atoms. ) is reacted with water or a metal oxide, to obtain a hydroalkoxysilane compound (2) represented by general formula (1):

(1)
(wherein ^R1 and ^R2 are as defined above) General formula (3)

(3)
(wherein ^X2 represents a halogen atom, and ^R1 represents a linear or branched alkyl group having 2 to 6 carbon atoms),
(R ² O) _n M (4)
( ^R2 represents a linear or branched alkyl group having 1 to 3 carbon atoms; M represents a hydrogen atom, an alkali metal, or an alkaline earth metal; and n is 1 or 2, and is 1 when M is a hydrogen atom or an alkali metal, and is 2 when M is an alkaline earth metal),

(1)
(wherein ^R1 and ^R2 are defined as above, and the sum of the carbon numbers of the alkyl groups represented by ^R1 and ^R2 is 4 or more and 9 or less. When R1 has ² carbon atoms, ^R2 has 2 carbon atoms. )