JP2005190828A - Porous material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a porous material, having a continuous pore structure in it, high in heat resistance, flexibility, and dimensional stability. <P>SOLUTION: This porous material contains a cross-linking structural body by metal-oxygen bond and a carbon atom covalently bonded to the cross-linking structure and has the condition, in which a void is closed or opened on its surface by adjusting the numerical aperture of the void on the surface, and has the continuous pore structure in which the voids are continuously connected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a porous body, a method for producing the same, a method for producing a fuel cell using the same, and a fuel cell.

  In recent years, porous bodies with pores on the order of submicron using a sol-gel reaction have been attracting attention as low-permittivity thin films used for proton conductive films and electrodes in fuel cells and interlayer insulation films in semiconductor devices. Have

  For example, the proton conductive membrane has a role of transmitting protons generated at the anode to the cathode side. This proton movement occurs in concert with the flow of electrons. That is, in PEFC, in order to obtain a high output, that is, a high current density, it is necessary to perform proton conduction at a sufficient amount and at a high speed. Therefore, it is no exaggeration to say that the performance of the proton conductive membrane is a key material that determines the performance of PEFC. The proton conductive membrane not only conducts protons but also serves as an insulating film that electrically insulates the anode and cathode, and a fuel barrier membrane that prevents fuel supplied to the anode from leaking to the cathode Also has a role as.

Further, Nafion (registered trademark), which has been conventionally used as a proton conductive membrane of a fuel cell, has a problem that it cannot be used at 80 ° C. or higher because it has flexibility but has insufficient heat resistance. However, it is desirable to use at 80 ° C. or higher in order to increase the power generation efficiency, and materials having a crosslinked structure have been proposed in order to improve heat resistance. For example, the addition of a conductive agent to a support made of a porous material has advantages in terms of improving mechanical strength and preventing swelling due to hot water, but at the interface between the conductive agent and the support, If the stress due to the change acts repeatedly, it may lead to interfacial peeling or destruction.
Furthermore, in this case, since the flexibility is not sufficient, there has been a problem that damage is likely to occur when a joined body with an electrode is manufactured, incorporated into a fuel cell, or when a fuel cell is operated.

  Further, along with remarkable progress of electronic devices such as computers, there are increasing demands for higher speed, lighter weight, and lower power consumption due to miniaturization of semiconductor devices. In response to these demands, miniaturization and high integration in ULSI (ultra-large scale integrated circuit) have been promoted in recent years, and one of the means for realizing this is high integration by multilayer wiring such as a microprocessor. .

And the biggest problem in this multilayer wiring is improvement of the function of the interlayer insulating film. Interlayer insulation films are required to have high functions such as high insulation, reduction of inter-wiring capacitance, reliable film formation in fine wiring spaces, and surface flattening, and various studies have been made. Improvement of adhesion and mechanical strength and reduction of dielectric constant are major issues.
As described above, there is a demand for a porous body having high mechanical strength and high porosity in both the proton conductive film of the fuel cell and the interlayer insulating film of the semiconductor device.

In such a situation, for example, it is substantially made of glass or glass ceramics, and has a hole diameter of 500 nm or more and a three-dimensional network-like continuous through hole, and a hole diameter of 5 to 100 nm formed on the inner wall surface of the through hole. The total volume of the pores is 10 m ³ / t or less, and the volume ratio of the through-holes to the whole is 20 to 90%, preferably 50 to 80%. An inorganic porous material characterized in that the volume ratio occupied by the pores is 10% or more, preferably 50% or more has been proposed (Patent Document 1).

  The porous body is phase-separated from a solvent containing an organic substance and burns out the organic substance, has a column shape, and is not flexible enough.

  And (1) tetraalkoxysilane, (2) at least one silane compound selected from the group consisting of dialkoxysilane and trialkoxysilane, and (3) polyethylene oxide (polyethylene glycol), polypropylene glycol and polyvinyl alcohol. There has been proposed an inorganic porous plate obtained by impregnating a woven or non-woven substrate of inorganic fibers with a liquid containing at least one organic polymer compound selected from the group consisting of, and firing it. (Patent Document 2).

Even with the above structure, the material is inorganic and therefore is not flexible enough.
Under such circumstances, there is a demand for a porous body having both flexibility and heat resistance in both the proton conductive film for fuel cells and the interlayer insulating film for semiconductor devices.

JP-A-6-265534 JP 2003-192464 A

  Thus, with the conventional porous body, a porous body having both heat resistance and flexibility could not be obtained. In addition, if an attempt is made to provide a physical property value that can be practically used for a semiconductor device such as an interlayer insulating film, the dielectric constant cannot be lowered sufficiently, and if an attempt is made to increase flexibility, heat resistance or mechanical There was a problem that sufficient strength could not be obtained.

This invention is made | formed in view of the said situation, The objective is to provide the porous body which has the void | hole state and surface state according to a use.
Another object is to provide a porous body having both heat resistance and flexibility.

Therefore, the porous body of the present invention provides characteristics according to the application by closing the pores on the surface or opening the pores.
The porous body of the present invention has a cross-linked structure by a metal-oxygen bond, has a continuous pore structure in which pores formed by the cross-linked structure are continuously connected, and at least the pores are the porous body. It is characterized by opening on one main surface side.
The porous body of the present invention is characterized in that the pores are open on both sides of the porous body.
The porous body of the present invention is characterized in that the pores are opened on one surface of the porous body and closed on the other surface.

According to such a configuration, it is possible to provide a porous body having a continuous pore structure in which pores are continuously connected inside. This makes it easy to adjust the membrane characteristics depending on whether the pores are blocked or opened by utilizing the fact that the pores are bicontinuous in three dimensions, with high heat resistance and flexibility. can do. The pores preferably have a continuous structure in the thickness direction of the porous body. For example, by opening both sides or one side, the moisture is easily discharged because the pores are co-continuous even if moisture is absorbed once. Therefore, the moisture resistance is also high. Note that this bicontinuous structure is mathematically a gyroidal or double giloid.
Gyroids), which means that the structure itself and the holes are connected continuously. (Reference: SCIENCE p1716, Vol.286, 26 Nov.1999)

Furthermore, since the flexibility is high, a buffering effect against a mechanical shock is great even when the temperature changes, and it is possible to provide a highly reliable structure or structure thin film even in a place where the temperature easily changes.
Moreover, since it is a porous body having a sufficient crosslinking density, a large dimensional change with respect to the environmental change is not seen, and the strength change is small.
In addition, a structure or a structure thin film having a high porosity can be provided while maintaining mechanical strength.
Further, when the pores are opened on one surface of the porous body and closed on the other surface, in addition to the above effects, the mechanical strength can be further improved because one surface is closed. it can.

In this structure, by adjusting the composition of the porous body (skeleton structure) that constitutes the crosslinked structure, the porosity can be adjusted and the dielectric constant can be easily adjusted while maintaining the mechanical strength of the film. Is possible.
Further, since the structure has a high porosity and the dielectric constant of air is low, a dielectric constant lower than that of adding fluorine can be obtained, and the dielectric constant can be greatly reduced.
In addition, this film can be applied as a desired functional film by filling the voids with various functional materials. For example, a material filled with a proton conductive material for a fuel cell has excellent mechanical properties such as fuel barrier properties and flexibility in addition to proton conductivity and heat resistance.

In addition, the porous body of the present invention has a cross-linked structure by a metal-oxygen bond, has a continuous pore structure in which pores formed by the cross-linked structure are continuously connected, and at least the pores are porous. It is characterized by being closed on both sides of the body.
With this configuration, it is possible to obtain a porous body that does not have pores on both sides and the internal continuous pores are blocked from the outside, so that water repellency, high porosity and heat resistance, flexibility, dimensions A porous body having both stability can be obtained. This structure has a low dielectric constant, excellent heat resistance, flexibility, mechanical properties, and moisture resistance, and can be used as, for example, an interlayer insulating film.

  In addition, since the porous body of the present invention has a porosity in the range of 40 to 80%, it has adequate mechanical strength and flexibility. Also, the dielectric constant can be kept low. In addition, if the porosity is in the range of 20 to 90%, it can be sufficiently applied depending on the form of use. If the porosity is smaller than this, sufficient flexibility cannot be obtained. On the other hand, if it is large, the mechanical strength is insufficient. The porosity is preferably 30 to 90%, and more preferably 40 to 80%. When the porosity is 50 to 60%, a high-quality porous body having both mechanical strength and flexibility can be obtained. Furthermore, when the porosity is too small, it is not possible to secure the amount of pores that should exhibit the desired function.

Further, the porous body of the present invention includes those in which the pore diameter is in the range of 0.001 to 1 μm on average.
With this configuration, a stable structure can be obtained if the average diameter of the pores is 0.001 μm to 1 μm. When the hole diameter is less than 0.001 μm, it is difficult to form the holes with a density sufficient to obtain a sufficient porosity, while when the hole diameter exceeds 1 μm, the mechanical strength is low. descend.
Moreover, when using for a fuel cell use, the range of the hole diameter of an average hole of 0.05-5 micrometers is desirable. When it is less than 0.05 μm, the filler cannot be sufficiently filled, and when it exceeds 5 μm, the mechanical strength is lowered. More preferably, the thickness is 0.1 to 1 μm, and a stable and excellent proton conductive membrane or electrode can be formed.
Further, when used for semiconductor applications such as an interlayer insulating film, the average hole diameter is preferably in the range of 0.0005 to 0.1 μm. When it is less than 0.0005 μm, a sufficient porosity cannot be obtained and a sufficiently low dielectric constant cannot be obtained. On the other hand, when it exceeds 0.1 μm, the mechanical strength decreases. More preferably, the pore diameter is preferably in the range of 0.001 to 0.01 μm. An average pore diameter of about 0.005 μm, a porosity of 70%, and a dielectric constant of about 1.9 is a stable structure, which is optimal as an interlayer insulating film.
As described above, when the pore diameter is too small, the porosity for expressing the desired function cannot be secured, and when it is too large, the mechanical strength is lowered.

（式中、Ｍは金属又はシリコン、ｘは架橋に関与する−Ｏ−結合又はＯＨ基であり、Ｒ^１は炭素数１〜５０の炭素原子含有分子鎖基であり、Ｒ^２はメチル、エチル、プロピル、又はフェニル基のいずれかの基を表し、ｎ_１，ｎ_２は０，１，または２のいずれかであり、ｎ_１，ｎ_２の少なくともひとつが１または２である） Moreover, the porous body of this invention contains what is a structure shown by following formula (1).

(In the formula, M is a metal or silicon, x is an —O— bond or OH group involved in crosslinking, R ¹ is a carbon atom-containing molecular chain group having 1 to 50 carbon atoms, and R ² is methyl or ethyl. , Propyl, or phenyl group, n ₁ , n ₂ are either 0, 1, or 2, and at least one of n ₁ , n ₂ is 1 or 2)

  According to such a structure, a porous body having sufficient flexibility and mechanical strength can be obtained. Moreover, as a dielectric constant, a value of 2.0 or less could be obtained, no damage was observed against bending, and the heat resistance was good.

Here, when the number of carbon atoms exceeds 50, crosslinking is insufficient, and heat resistance and mechanical properties cannot be expected. In addition, when R ¹ has some kind of heteroatom, it may be cleaved by acid or heat, but the hydrocarbon compound is extremely stable because it is not easily attacked by these acid or heat. Examples of the hydrocarbon group include an alkylene chain and an aromatic chain.

Desirably, in the porous body, M is silicon.
According to such a configuration, these have the effect of being stable even in a strong acid, high temperature and high humidity environment. Silicon is effective because it does not adversely affect the semiconductor device.

  This metal-oxygen bond is effective in the case of an aluminum-oxygen bond, a titanium-oxygen bond, a zirconium-oxygen bond, etc. in addition to a silicon oxygen bond, and these are stable even in a strong acid, high temperature and high humidity environment. .

    Further, silicon-oxygen bonds are mainly used, and metal-oxygen bonds, phosphorus-oxygen bonds, boron-oxygen bonds, or the like may be used in combination. The atomic ratio between silicon and metal elements is preferably 50 mol% or more when the total metal atoms are 100 mol%.

The porous body of the present invention includes those in which R ¹ in the formula (1) is a hydrocarbon group.

Since R ¹ is a hydrocarbon group, it is a molecular chain that controls flexibility and film properties, and is unstable when there are no carbon atoms.

The hydrocarbon group is preferably a structure represented by the following formula (2).

Desirably, n in the formula (2) is in the range of 1-20.

When R ¹ has a branch, the bond connecting the bridges may be broken. In addition, when an aromatic compound is contained, decomposition or reaction occurs mainly due to the benzyl position as an active site, the stability as a film may be inferior, and the dielectric constant increases. On the other hand, in the above configuration of the present invention, since R ¹ is a linear polymethylene chain, it is stable against various external factors, and the moisture resistance characteristics of the film to be produced due to the hydrophobicity of the hydrocarbon chain. Becomes effective as an insulating film.

  In addition to the stability, since the linear polymethylene chain is a bendable structure, it is possible to impart an appropriate flexibility to the film and to adjust the denseness and the like. These adjustments can be achieved mainly by adjusting the molecular length of the polymethylene chain.

  As raw materials for introducing silicon-oxygen bridges at both ends of the polymethylene chain, various bis (hydrolyzable silyl) polymethylenes are known. For example, polymethylene is ethylene, hexamethylene, octamethylene, nonamethylene Is commercially available (Gelest).

In addition, a hydrosilylation reaction is performed on 1,3-butadiene, 1,9-decadiene, 1,13-tetradecadiene, etc. having unsaturated bonds at both ends, so that R ¹ is tetramethylene. The raw materials corresponding to decamethylene and tetradecamethylene can be easily synthesized, and any polymethylene chain having up to 20 carbon atoms can be synthesized.

  Furthermore, the molecular length of polymethylene is preferably 1 to 20 as described above, and can exhibit satisfactory performance with respect to any of heat resistance, flexibility, and water resistance. In particular, those having a molecular length of around 10 are preferred.

式中、ｘは架橋に関与する−Ｏ−結合又はＯＨ基であり、ｎ_１，ｎ_２は０，１，または２のいずれかであり、ｎ_１，ｎ_２の少なくともひとつが１または２である。 In the formula (1), R ¹ is octamethylene and R ² is a methyl group, and it is desirable that the structure be represented by the following formula (3).

In the formula, x is an —O— bond or OH group involved in crosslinking, n ₁ and n ₂ are either 0, 1, or 2, and at least one of n ₁ and n ₂ is 1 or 2. is there.

  Thereby, since it is a structure in which methylene is linked in eight, the raw material can be easily obtained.

A structure having Si—O crosslinked structures at both ends of these polymethylenes is extremely stable and useful as a basic crosslinked structure of an insulator. This porous body may be a mixture of a plurality of types of molecules. For example, it is possible to adjust the crosslink density and the like by mixing and using a porous body of n ₁ = 1 and a porous body of n ₂ = 2. As a result, the void structure of the film, flexibility, etc. Can be adjusted.

  The physical properties can also be adjusted by mixing organic-inorganic composite structures having different organic chain lengths and types of substituents.

The method for producing a porous body of the present invention includes a step of preparing a mixture containing a metal-oxygen bond crosslinkable material, a solvent, and a catalyst, a step of supplying the mixture onto a substrate, and the mixture as described above. Forming a porous body having a continuous pore structure in which a sol-gel reaction is performed on a substrate, having a crosslinked structure due to a metal-oxygen bond, and pores formed by the crosslinked structure are continuously connected, and Prior to the step of supplying the mixture onto the substrate, the composition of the mixture or the surface state of the substrate is adjusted so that the open state of the pores at the interface between the porous body and the substrate becomes a desired state. And a step of adjusting.
According to this method, by controlling the affinity (wetting property) between the solvent and the substrate by adjusting the contact angle, it is easy to adjust whether the surface state of the pores is an open state or a closed state. And a desired porous body can be obtained efficiently.
That is, when a mixture of a material having a crosslinking group and a solvent is subjected to a sol-gel reaction, a crosslinked product is formed by polycondensation, and its molecular weight gradually increases. As the molecular weight increases, the solvent progresses from a state soluble in the solvent toward a phase separation that becomes insoluble, but at a certain molecular weight, the polymer is continuously connected in a three-dimensional network and the solvent. Form a three-dimensionally connected state (co-continuous structure).
This state is transitional, and is adjusted to the condition that the structure can be frozen by gelation at the same time when this structure is formed by the amount of solvent, catalyst concentration, and amount of water. Here, when the polymer and the solvent are separated, if the substrate is made solvophilic, the polymer and the solvent can be phase-separated on the surface of the substrate, and the substrate opens.
On the other hand, when the substrate is made to have solvent repellency, phase separation does not occur on the surface of the substrate, a polymer film is formed, and no openings are formed.

Further, in the method for producing a porous body of the present invention, prior to the supplying step, the substrate surface is controlled so that phase separation between the polymer produced by the sol-gel reaction and the solvent occurs on the substrate surface. It is characterized by being solvent-borne.
That is, when the surface energy of the polymer, the solvent, and the substrate is T _P , T _S , and T _B , respectively, the solvent, the substrate, and the polymerization are such that | T _S −T _B | ≦ | T _P −T _B | By selecting a material for producing a product, a porous body opened on the surface of the substrate can be obtained.
At this time, the solvent does not have to be a pure solvent, for example, it contains some precursor monomers, or for the purpose of controlling the surface energy, ethylene glycol, polyethylene glycol, polyethylene oxide, polypropylene glycol, polyvinyl alcohol. A polar substance that dissolves in the solvent may be included.

In the method for producing a porous body of the present invention, the substrate includes a substrate whose contact angle with the solvent is 30 degrees or less.
By this method, it is possible to obtain a porous body having pores opened in the substrate.

In the method for producing a porous body of the present invention, after the supplying step, prior to the phase separation step, a substance having a contact angle with the solvent of 30 degrees or less is also applied to the surface facing the substrate. A step of contacting.
By this method, a porous body in which pores are opened on both sides can be obtained. The substance to be contacted here may be solid, liquid or gas.

  In the method for producing a porous body of the present invention, prior to the step of supplying the mixture onto the substrate, phase separation between the polymer formed by the sol-gel reaction and the solvent does not occur on the surface of the substrate. Further, the substrate surface is made to have solvent repellency.

That is, when the surface energy of the polymer, solvent, and substrate is T _P , T _S , and T _B , respectively, the solvent, substrate, and polymerization are such that | T _S −T _B |> | T _P −T _B | By selecting a material for generating a product, a porous body with closed pores on the surface of the substrate can be obtained.
Here, the solvent may not be a pure solvent. For example, some of the precursor monomers may be included, or other substances may be positively included for the purpose of controlling the surface energy.

  Moreover, the manufacturing method of the porous body of this invention contains what the contact angle of the said solvent with respect to the said base | substrate surface exceeds 30 degree | times.

In the method for producing a porous body according to the present invention, after the supplying step, prior to the phase separation step, a substance having a contact angle with the solvent larger than 30 degrees is also brought into contact with the surface facing the substrate. Including the step of
By this method, a porous body having pores closed on both sides can be obtained.

In the method for producing a porous body according to the present invention, a substance having a contact angle with the solvent of 30 degrees or less is also brought into contact with the surface facing the substrate after the supplying step and before the phase separating step. A step of causing
By this method, it is possible to obtain a porous body in which pores are closed on the substrate side and open on the opposite surface side.

  If the surface facing the substrate is opened and cured while being in contact with air, a surface state corresponding to the contact angle with air is obtained. Usually, the aperture ratio is about 30%.

  In the method for producing a porous body of the present invention, the step of preparing the mixture includes a mixture containing a plurality of crosslinkable silyl groups and an organic-inorganic composite crosslinkable compound having a carbon atom covalently bonded thereto. And a step of forming a film of the mixture on a substrate and a step of condensing the crosslinkable silyl group to form a porous body having a continuous pore structure.

  Crosslinking of Si—O by hydrolysis and subsequent dehydration condensation reaction using a plurality of crosslinkable silyl groups, ie, an organic-inorganic composite crosslinkable compound having a hydrolyzable silyl group and a carbon atom covalently bonded thereto. Form the body. Here, the hydrolyzable silyl group is an alkoxysilyl group in which an alkoxy group such as methoxy, ethoxy, propoxy or phenoxy is directly bonded to a silicon atom, a halogenated silyl group in which a halogen such as chlorine is bonded to a silicon atom, and an acetoxy group And carboxysilyl group. Furthermore, a silanol group or silanolate group hydrolyzed in advance can be used. In this case, hydrolysis is not necessary, and only the condensation reaction may be performed.

  Preferably, the condensation step includes a step of adding an amount of a catalyst necessary for the crosslinkable silyl group to cause a condensation reaction in an equivalent equivalent system.

  As a result, the reaction rate is appropriately maintained, the condensation reaction is surely caused, and a good network structure is formed, so that a regular continuous pore structure can be formed. Here, the pores are formed by utilizing phase separation with a solvent accompanying an increase in molecular weight due to a condensation reaction. The formation of the three-dimensional network structure is greatly influenced by the hydrolysis rate and the condensation reaction rate, and it is necessary to appropriately adjust the temperature and the catalyst concentration.

In the cross-linking reaction step, the target film can be obtained by heating at any temperature from room temperature to 300 ° C.
In the case of heating in this step, a known method such as pressure heating with an oven can be used. Moreover, when performing this method, in order to perform a hydrolysis and condensation efficiently, you may make it add water to a mixed solution previously, and you may make it heat under water vapor | steam.

  In order to accelerate the production of the crosslinked structure, an acid such as hydrochloric acid, sulfuric acid, phosphoric acid or the like may be added to the reaction system in advance as a catalyst. In addition, since the cross-linking structure is accelerated by a base, a base catalyst such as an inorganic compound such as ammonia or sodium hydroxide or an organic compound such as an amine compound may be used.

  Preferably, the catalyst is a Bronsted acid. By using Bronsted acid, it is possible to form a better three-dimensional network structure.

  The condensation step includes a step of adding 0.5 to 1.5 equivalents of water to the crosslinkable silyl group. For example, the catalyst amount may be adjusted so that 0.5 to 1.5 equivalents of water is present.

前駆体の添加量：ｘ (mol)
Ｒ^５のモル数：２（３−ｎ）ｘ(mol)
触媒の添加量：ｚ(l)
触媒の比重：σc
触媒の濃度：Ｎｃ（規定）
触媒の分子量：Mc
水の分子量：Ms Desirably, the Bronsted acid catalyst is an aqueous solution, the concentration N (normative) is in the range of 5 ≦ N ≦ 10, and the addition amount is in the range represented by the following formula. And

Amount of precursor added: x (mol)
Number of moles of R ⁵ : 2 (3-n) x (mol)
Amount of catalyst added: z (l)
Specific gravity of catalyst: σc
Catalyst concentration: Nc (normative)
Molecular weight of catalyst: Mc
Water molecular weight: Ms

  When the value of the relational expression is smaller than 0.5, the reaction is slow, the hydrolysis rate is too small, the formation of the co-continuous structure and the timing of gelation do not match, and the network structure is not formed.

On the other hand, when the value of the above relational expression is larger than 1.5, the amount of added water is increased and the reaction is too early, the formation of the co-continuous structure and the timing of gelation do not coincide, and the network structure cannot be formed.
Here, 0.5 and 1.5 represent the ratio of added water to the number of cross-linking groups, respectively, and in the case of 1.0, it means that the same amount of water is blended as when all cross-linking groups are hydrolyzed.

  The amount of solvent in the reaction is set so that the porosity is 60% = 1.8 ml / g. The amount is 0.5 ml / g to 10 ml / g, preferably 1 ml / g to 5 ml / g, based on the fixed amount (g) of the precursor. If it is less than this, it is difficult to form continuous pores, and even if it can be formed, the strength as a support is insufficient.

式中、Ｍは金属又はシリコン、Ｒ^１は炭素数１〜５０の炭素原子含有分子鎖基であり、Ｒ^２はメチル、エチル、プロピル、又はフェニル基のいずれかの基を表し、Ｒ^５はＣｌ，ＯＣＨ_３，ＯＣ_２Ｈ_５，ＯＣ_６Ｈ_５，ＯＨ又はＯＣＯＣＨ_３基のいずれかの基を表し、ｎ_１，ｎ_２は０，１，または２のいずれかであり、ｎ_１，ｎ_２の少なくともひとつが１または２である。 Preferably, the precursor solution is a structure represented by the following formula (4).

In the formula, M is a metal or silicon, R ¹ is a carbon atom-containing molecular chain group having 1 to 50 carbon atoms, R ² represents any group of methyl, ethyl, propyl, or phenyl group, and R ⁵ is Cl, OCH ₃ , OC ₂ H ₅ , OC ₆ H ₅ , OH or OCOCH ₃ group is represented, and n ₁ and n ₂ are either 0, 1, or 2, and n ₁ , n _At least one of 2 is 1 or 2.

Preferably, the M is silicon.
Desirably, R ¹ in the formula (4) is a hydrocarbon group.

Desirably, the said hydrocarbon group is a structure shown by following formula (5).

  Desirably, n in the formula (4) is in the range of 1-20.

式中、Ｒ^５はＯＣＨ_３またはＯＣ_２Ｈ_５基を表し、ｎ_１，ｎ_２は０，１，または２のいずれかであり、ｎ_１，ｎ_２の少なくともひとつが１または２である。 Desirably, R ¹ in the formula (4) is octamethylene and R ² is a methyl group, and is represented by the following formula (6).

In the formula, R ⁵ represents an OCH ₃ or OC ₂ H ₅ group, n ₁ and n ₂ are either 0, 1, or 2, and at least one of n ₁ and n ₂ is 1 or 2.

  Examples of these crosslinkable precursors include bis (diethoxymethylsilyl) ethane, bis (diethoxymethylsilyl) hexane, bis (diethoxymethylsilyl) octane, bis (diethoxymethylsilyl) nonane, and bis (di-). Ethoxymethylsilyl) decane, bis (diethoxymethylsilyl) tetradecane, bis (dimethylethoxysilyl) ethane, bis (dimethylethoxysilyl) hexane, bis (dimethylethoxysilyl) octane, bis (dimethylethoxysilyl) nonane, bis (dimethyl Ethoxysilyl) decane, bis (dimethylethoxysilyl) tetradecane and the like.

  In addition, a bridge | crosslinking process is performed at 100-300 degreeC here. Or it is desirable to perform aging at 100-300 degreeC.

  When this porous body is used at a high temperature of 100 ° C. or higher, it is desirable to heat it at a high temperature higher than the use temperature. In this heating, the crosslinking step may be performed at 100 ° C. to 300 ° C. as it is, or the crosslinking step is sol-gel cured at 5 to 40 ° C. for 2 hours or more, and then the heating step at 100 to 300 ° C. is performed. Also good.

  As a heating method, in addition to heating with a normal heat source, far infrared heating, electromagnetic induction heating, microwave heating, or the like may be used. Moreover, you may use together.

  Moreover, you may wash the film | membrane obtained in these processes with water as needed. The water used at that time is preferably water containing no metal ions, such as distilled water or ion-exchanged water.

  Further, after the film is obtained in this way, it may be further crosslinked by irradiation with ultraviolet rays or electron beams.

  In addition, a polymer that dissolves in a solvent such as ethylene glycol, polyethylene glycol, polyethylene oxide, polypropylene glycol, or polyvinyl alcohol may be added to the precursor solution as a phase separation regulator.

In the method for producing a porous body according to the present invention, the base is a semiconductor substrate having a desired element region and a wiring layer, and the surface of the semiconductor substrate is subjected to a hydrophobic treatment prior to the step of supplying the precursor. It includes a step of performing.
By this method, an interlayer insulating film with closed pores can be easily obtained, and the moisture resistance is higher. This is particularly effective when used as the uppermost passivation film. For example, a semiconductor device includes an interlayer insulating film interposed between a first wiring conductor formed on a semiconductor substrate or a semiconductor substrate and a second wiring conductor, and the interlayer insulating film is made of silicon- It is characterized in that it is composed of a porous body having a continuous pore structure including a cross-linked structure by an oxygen bond and a carbon atom covalently bonded thereto, and closed at the semiconductor substrate side and continuously connected. To do.

According to such a configuration, the dielectric constant of the interlayer insulating film can be reduced, so that the interlayer capacitance can be reduced and a semiconductor device driven at high speed can be provided.
Also, the moisture resistance is high. Furthermore, since it can be formed at a low temperature, a highly reliable film can be formed without affecting the base.

  In addition, a passivation film is formed on the surface of the semiconductor device, and the passivation film includes a crosslinked structure formed by a silicon-oxygen bond and a carbon atom covalently bonded thereto, and the pores are closed on both sides. In addition, those composed of a porous body having a continuous pore structure connected continuously are also effective.

  According to such a configuration, it is possible to form a closed structure that does not have openings in the upper layer and the lower layer, and it is possible to form an effective passivation film that is extremely excellent in moisture resistance and highly reliable.

Further, in the method for producing a fuel cell of the present invention, prior to the step of supplying the mixture, a gas diffusion electrode having a surface polarity controlled so as to have a solvophilic surface is prepared, and the gas diffusion electrode is used as a base. Forming the mixture directly on the gas diffusion electrode so as to form an opening on the gas diffusion electrode and its opposite surface side.
According to this method, a porous film having openings on both sides can be directly formed on the surface of the gas diffusion electrode by controlling the surface polarity of the gas diffusion electrode surface and the opposite surface side. It is possible to form the electrode without contact with foreign substances on the interface of the adhesive film, preventing contamination of the interface and forming an electrode with high adhesion. In addition, since the diffusion electrode itself is used as the substrate without using a separate substrate, a highly reliable fuel cell can be formed with good workability.

  Moreover, this invention contains the porous body formed by the manufacturing method of the said porous body.

Further, the present invention is to form a gas diffusion electrode on both sides after introducing a proton conductive group into the pores of the porous body or supplying a proton conductive electrolyte to the surface of the porous body. Features.

Further, in the present invention, prior to the step of supplying the mixture, first and second gas diffusion electrodes whose surface polarities are controlled to prepare a solvophilic surface are prepared, and one of the first gas diffusion electrodes is prepared. And supplying the mixture directly onto the first gas diffusion electrode, prior to condensation of the mixture, a proton conductive group is added to the first gas diffusion electrode supplied with the mixture. After introducing or forming a proton conductive electrolyte on the surface of the mixture, the step of bringing the second gas diffusion electrode into contact with the surface of the first gas diffusion electrode supplied with the mixture and completely curing it. Including.
By this method, the MEA of the fuel cell can be formed without a special bonding step, and it becomes possible to form the MEA with good interface characteristics of the electrode proton conductive membrane. In addition, since the diffusion electrode itself is used as a base or a lid without using a separate base, a highly reliable fuel cell can be formed with good workability.

In addition, the fuel cell of the present invention is configured using the membrane-electrode assembly (MEA) formed by the above method.
According to this method, since the porous body can be formed directly on the gas diffusion electrode, it can be formed without contacting foreign substances on the interface between the electrode and the proton conductive membrane, and contamination of the interface is prevented. Highly adherent electrode formation can form highly reliable fuel cells with good workability

As described above, the porous body of the present invention has a continuous pore structure in which pores are continuously connected, (i) a porous body having no openings on both front and back surfaces, and (ii) an opening on one side. Depending on the application, such as a porous body having a portion and one side having no opening, (iii) a porous body having both front and back openings, dimensions, moisture resistance, mechanical properties, heat resistance, flexibility, dimensions It is a material whose opening state can be adjusted so as to have stability.
In addition, this porous body is formed by adjusting the affinity (wetting property) of the solvent with respect to the substrate, and can be easily operated by adjusting the contact angle of the solvent of the precursor solution with respect to the substrate. The opening state according to a use can be acquired with sufficient property.
It is also possible to provide a porous body having a continuous pore structure having a small relative dielectric constant, high moisture resistance, high flexibility and excellent mechanical properties.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As described above, the porous body of the present invention has a continuous pore structure in which pores are continuously connected. By adjusting the contact angle between the substrate and the upper layer, as shown below, (i ) A porous body having no openings on both sides, (ii) a porous body having openings on one side, a porous body having no openings on one side, and (iii) a porous body having openings on both sides be able to.

(I) The composition of the mixture supplied to the substrate and the substrate surface are adjusted so that the contact angle with the porous substrate surface having no openings on both the front and back surfaces exceeds 30 degrees, and the top surface also has a contact angle prior to phase separation. Is coated with a material having a temperature exceeding 30 degrees, cured, and phase-separated to form a porous material having no openings on both the front and back surfaces as shown in FIGS. 4 (a) and 4 (b). Can be obtained.

(Ii) a porous body having an opening on one side, a porous body having no opening on one side,
When the composition of the mixture supplied to the substrate and the substrate surface are adjusted so that the contact angle with the substrate surface is 30 degrees or less, and the upper surface is coated with a material having a contact angle with the solvent exceeding 30 degrees, A porous body having an opening only on the side (lower) surface and no opening on the upper surface can be obtained.
When the solvent and the substrate are added so that the contact angle with the substrate surface exceeds 30 degrees, and the upper surface is configured so that the contact angle with the air surface or the solvent is 30 degrees or less, FIGS. ), A porous body having no opening only on the substrate side (lower) surface can be obtained.

(Iii) a porous body having openings on both front and back surfaces;
When the solvent and the substrate are selected so that the contact angle with the substrate surface is 30 degrees or less, a porous body having a double-sided opening is obtained as shown in FIGS. 5 (a) and 5 (b). Can do.
In addition, the solvent and the substrate are selected so that the contact angle with the substrate surface is 30 degrees or less, and prior to phase separation, the top surface is coated with a material that also has a contact angle of 30 degrees or less, and is cured and phase separated. As shown in FIGS. 6A and 6B, a porous material having no openings on both the front and back surfaces can be obtained.

(Embodiment 1)
As a first embodiment of the present invention, there is provided (i) a semiconductor integrated circuit including a MOSFET using a low dielectric constant thin film formed using a porous body having no openings on both front and back surfaces as an interlayer insulating film. The semiconductor device will be described.

  In the present embodiment, a crosslinkable precursor as described later is prepared, and the catalyst amount is adjusted so that 0.5 to 1.5 equivalents of water is present with respect to the crosslinkable silyl group as the crosslinkable precursor. A Bronsted acid catalyst added in a controlled manner is added to cause a condensation reaction, which includes a cross-linked structure with silicon oxygen bonds and a carbon atom covalently bonded thereto, as shown in FIGS. 2 (a) and 2 (b). As shown in the electron micrograph of FIG. 2 (b) is an enlarged view of the main part of FIG. 2 (a), a low dielectric constant thin film having a continuous pore structure in which pores are continuously connected is formed, This is used as an interlayer insulating film 7 to form a semiconductor device (see FIG. 1).

  As shown in FIG. 1, this semiconductor device is formed by forming an element region such as a MOSFET on a silicon substrate 1 on which an insulating film 2 for element isolation is formed and forming a multilayer wiring on the surface. A precursor formed by dissolving 1,8-bis (diethoxymethylsilyl) octane and 1,8-bis (dimethylethoxylyl) octane, which is a monofunctional precursor, in isopropanol and adding hydrochloric acid as interlayer insulating film 7 The body solution is characterized by using a low dielectric constant thin film formed by causing a condensation reaction on the surface of the semiconductor device.

  This semiconductor device has an LDD structure comprising a gate electrode 4 formed through a gate oxide film 3 formed on the surface of a silicon substrate 1, low concentration impurity diffusion regions 5a and 5b, and high concentration impurity diffusion regions 6a and 6b. Via a contact hole 9 formed in a MOSFET composed of a source / drain region, a first layer wiring 8 in contact with one of the source / drain regions, and an interlayer insulating film made of the low dielectric constant thin film of the present invention. The second-layer wiring 10 formed is provided. Reference numeral 11 denotes a passivation film formed so as to cover the semiconductor device.

A manufacturing process of this semiconductor device will be described with reference to FIGS.
First, the gate electrode 4 formed on the surface of the silicon substrate 1 through the gate oxide film 3 is formed. Then, impurity diffusion is performed using the gate electrode 4 as a mask to form low-concentration impurity diffusion regions 5a and 5b constituting the source / drain regions (FIG. 3A).

  Subsequently, a silicon oxide film is formed on the upper layer by CVD, and anisotropic etching is performed to form a sidewall 3s on the side wall of the gate electrode (FIG. 3B).

  Then, high-concentration impurity diffusion is performed using the gate electrode 4 with the side wall 3s formed as a mask to form high-concentration impurity diffusion regions 6a and 6b, and source / drain regions having an LDD structure are formed (FIG. 3C). )).

  Next, using the method of the present invention as the interlayer insulating film 7, as shown in FIGS. 4A and 4B, the pores are closed on both the front and back surfaces, and the pores are continuously connected. A low dielectric constant thin film is formed. Here, the surface of the base is subjected to hydrophobic treatment, and ethylene glycol is added to the precursor solution, which is applied by spin coating so that the contact angle is 50 degrees or more. On the other hand, prior to the sol-gel reaction, the surface to which the precursor solution is applied is also subjected to hydrophobic treatment. In this way, it is possible to perform phase separation and easily form a porous thin film having a structure in which pores are closed on both sides. FIG. 2 is a sectional view of the low dielectric constant thin film, and FIGS. 4A and 4B are a top view and a bottom view thereof. As is apparent from FIGS. 4A and 4B, neither the upper surface nor the lower surface has an opening and is in a closed state.

  A contact hole 9 was formed in the interlayer insulating film made of this low dielectric constant thin film by photolithography (FIG. 3D).

  Thereafter, as shown in FIG. 3E, the second layer wiring 10 was formed. Finally, this low dielectric constant thin film was formed as the passivation film 11 using the same method. When forming the passivation film 11, ethylene glycol is added to the precursor solution to form a low dielectric constant thin film made of a porous body having a structure in which both surfaces are closed.

  According to this method, since a porous body having a continuous pore structure in which both surfaces are blocked is formed, a low dielectric constant thin film having high moisture resistance and high mechanical strength can be formed at a low temperature. During film formation and use, it acts not only as a film itself but also as a buffer film that relieves stress on the upper and lower layers, and a highly reliable semiconductor device can be provided.

  In addition, about the composition of a precursor solution, it can prepare suitably, without being limited to the composition of the said embodiment.

  However, in the said Example, although the catalyst for hydrolyzing a silyl group was comprised by the Bronsted acid, it can change suitably, without being limited to a Bronsted acid.

  Furthermore, the film may be heated and fired after film formation, and the heating atmosphere can be selected as appropriate, such as an oxygen atmosphere, air, nitrogen atmosphere, or reduced pressure.

  Moreover, heat resistance and moisture resistance improve by adding a heating process. In addition, when used as a passivation film or an interlayer insulating film, it is possible to reduce the leakage current.

  Further, when the precursor solution is formed, preliminary crosslinking may be performed by heating.

  In the above embodiment, the precursor liquid is supplied to the substrate by the spin coating method. However, a coating method, a dip coating method in which a film is immersed in the precursor solution, or the like may be used.

That is, the substrate is lowered at a desired speed with respect to the liquid level of the precursor solution, submerged in the solution, and allowed to stand.
Then, after the desired time has elapsed, the substrate is lifted vertically at a desired speed and removed from the solution.

  And if necessary, a porous body having a continuous pore structure with a high porosity is formed by heating and firing.

(Embodiment 2)
As a second embodiment of the present invention, a (iii) proton conductive membrane configured using a porous body having openings on both front and back surfaces will be described.
In the method for producing a proton conductive membrane of the present invention, a step of forming (forming a film) a precursor solution similar to that used in the first embodiment is used.
First, a precursor solution similar to that used in the first embodiment is prepared.
Then, a substrate having a solvophilic surface is prepared, and a coating film is formed on the surface by a coating method so that the dry film thickness is 50 μm on the substrate surface.

After this, when a solvophilic lid is placed on the surface opposite to the substrate surface and heated, a porous body is formed in which the phase separation from the solvent occurs and the both surfaces become open as polymerization proceeds by the condensation reaction. To do.
The difference from the first embodiment is only that the base and the lid are adjusted so as to have a solvophilic surface, and the others are the same.

  Thus, after removing a base | substrate from the porous body which both surfaces opened, this porous body is filled with the mixture of a crosslinkable compound and an acid containing compound, and the crosslinkable silyl group contained in this filled mixture is included. Is hydrolyzed and condensed to form a cross-linked structure of the proton conductive structure inside the porous membrane.

A gas diffusion electrode sheet is laminated on both sides of the thus formed proton conductive membrane, and a membrane / electrode assembly, so-called MEA (Membrane), which is a joined body of the proton conductive membrane and the electrode by hot pressing or the like. Electrode Assembly) is formed and integrated with a separator or the like to produce a fuel cell.

This method will be described in detail below.
(Film formation process)
In order to form the precursor solution into a film, a known method such as casting, coating, or casting can be used. The method for forming the film is not particularly limited as long as a uniform film can be obtained. The thickness of the film is not particularly limited, but can be formed to have an arbitrary thickness between 10 μm and 1 mm. The proton conductive membrane for a fuel cell is appropriately determined from the proton conductivity, fuel barrier properties, and mechanical strength of the membrane, and usually a membrane having a thickness of 20 to 300 μm can be preferably used. The thickness of the proton conductive membrane of the invention is also produced according to this.

  In addition, when performing this film forming step, the surface of the substrate is made solvophilic prior to supply to the substrate. For example, it may be selected according to the precursor solution so that the substrate itself becomes solvophilic or the surface of these substrates may be subjected to solvophilic treatment. The same applies to the upper surface. By subjecting the base and the upper surface to solvophilic treatment in this way, the contact angle is reduced and a proton conductive membrane having an opening on the surface can be obtained. In addition, you may add a fiber, a mat | matte, a fibril, or a reinforcing material to a precursor solution. The reinforcing material can be appropriately selected from glass materials, silicone resin materials, fluororesin materials, cyclic polyolefin materials, ultrahigh molecular weight polyolefin materials, etc. in consideration of heat resistance and acid resistance.

(Condensation process)
The proton conductive membrane in the present invention is characterized in that a crosslinked structure is formed by hydrolysis and condensation of an alkoxysilyl group or the like, stably exhibits proton conductivity even at high temperatures, and has little shape change. Such generation of Si—O—Si bonds by hydrolysis or condensation of alkoxysilyl groups or the like is well known as a sol-gel reaction.
In the sol-gel reaction, a catalyst is usually used for accelerating and controlling the reaction. As the catalyst, an acid or a base is usually used.

Although the condensation reaction can be performed at room temperature, it is preferable to perform heating in order to shorten the reaction time and perform more efficient curing. Heating may be performed by a known method, and heating by an oven, pressure heating by an autoclave, far infrared heating, electromagnetic induction heating, microwave heating, or the like can be used. Heating can be performed at any temperature from room temperature to 300 ° C, preferably at 100 to 250 ° C. At this time, heating may be performed under an inert gas or the like under reduced pressure, nitrogen, or argon.

In addition, a method of avoiding sudden environmental changes, such as heating at room temperature for a certain amount of time and then gradually increasing the temperature to a high temperature, may be employed.
Moreover, in order to replenish water required for hydrolysis, it may be performed under water vapor, and may be performed under solvent vapor in order to prevent rapid membrane drying.
The membrane that has undergone the condensation step may be subjected to water washing to remove unreacted substances and curing catalyst, and may further be subjected to ion exchange with sulfuric acid or the like.

(Introduction of proton conductive structure)
After removing the substrate from the porous membrane thus formed, the porous body is filled with a mixture of a crosslinkable compound and an acid-containing compound, and the crosslinkable silyl contained in the filled mixture. By crosslinking and condensing groups, a cross-linked structure of the proton conductive structure is formed inside the porous membrane.
The catalyst used for forming the proton conductive membrane by introducing the proton conductive structure into the porous membrane may be an acid or a base.

  When an acid is used as the catalyst, a Bronsted acid such as hydrochloric acid, sulfuric acid, phosphoric acid or acetic acid is used. The type, concentration, etc. of the acid are not particularly limited as long as it is within the available range. Of these, hydrochloric acid has a relatively low acid residue after the reaction and can be suitably used. When hydrochloric acid is used, the concentration and the like are not particularly limited, but those of 0.01 to 12N are usually used.

  When a base is used as the catalyst, sodium hydroxide, potassium hydroxide, ammonia, an amine compound or the like is used. In general, it is known that when an acid is used, hydrolysis and condensation compete with each other, resulting in a linear cross-linked structure with few branches. On the other hand, when a base is used as a catalyst, It is known that the dendritic structure has many branches because hydrolysis occurs at once. In the present invention, any method can be used in consideration of film physical properties.

The amine compound can be used without any particular limitation, but usually a compound having a boiling point of 50 to 250 ° C. is preferably used, and specific examples of easily available amine compounds within this range include triethylamine, dipropylamine, and isobutylamine. , Diethylamine, diethylethanolamine, triethanolamine, pyridine, piperazine, tetraethylammonium hydroxide and the like, and any of them can be suitably used.
Furthermore, it is also effective to use a combination of catalysts, such as forming a film with an acid catalyst in advance and then adding a base to perform hydrolysis and condensation later.
Furthermore, you may use together potassium fluoride and ammonium fluoride as a catalyst. These mainly have a function of accelerating the condensation reaction, and can be suitably used because the reaction can be controlled independently of the hydrolysis.
The addition amount of the catalyst can be arbitrarily set, and is appropriately determined in consideration of the reaction rate, compatibility with the film raw material, and the like.

The manufacturing method described above is an example, and the desired proton conductivity can be obtained by adjusting the contact angle so as to form a porous body having pores opened on the front surface and the back surface, even by other methods. A film can be formed.
By using the porous body of the present invention, a proton conductive membrane having high mechanical strength and excellent flexibility and heat resistance could be obtained.

(Fabrication of fuel cell)
A gas diffusion electrode sheet having a platinum-supported conductor is laminated on both sides of a porous membrane (proton conductive membrane) containing a proton conductive structure inside the pores formed as described above, and hot pressing A membrane / electrode assembly, so-called MEA, is produced by pasting with the above. Furthermore, an electronic conductive plate separator having a fuel introduction gas flow path is laminated on both sides of the MEA, and a fuel cell can be manufactured by integrally fixing together with a sealing material, a gasket, and the like. In addition, a desired fuel cell output can be exhibited by constructing a stack structure in which a plurality of the cell units are connected in series in the stacking direction.

(Embodiment 3)
Further, in the above embodiment, the MEA was prepared by laminating the gas diffusion electrode sheets on both sides of the porous membrane. However, the same gas diffusion electrode sheet, which is made solvophilic by controlling the polarity, is a base. The porous body is directly formed, the electrolyte is filled, and a proton conductive membrane is formed. Further, a gas diffusion electrode is formed on the proton conductive membrane to integrally form the MEA. You may do it.

  Namely, 0.73 g of 1,8-bis (diethoxymethylsilyl) octane and a solution of monofunctional precursor 1,8-bis (dimethylethoxylyl) octane 0.61 in 1.2 ml of isopropanol and 8N Then, 0.28 g of hydrochloric acid and 1.2 ml of isopropanol were combined and stirred for several tens of seconds to form a precursor solution.

This precursor solution was then added to the solvophilic gas diffusion electrode (E-TEK) with proton conductivity.
(It may be prepared from a commercially available product such as solvophilic carbon and Nafion solution.) It is directly coated on the surface of the substrate by a bar coater cast method. Then, after covering with a lid such as a 20 × 30 mm plastic case, it is cured at room temperature (20 ° C.) for 12 hours, then heated and cured at 80 ° C. for 24 hours, and further at 150 ° C. for 24 hours, A porous body layer having a thickness of 50 μm and having elasticity was formed.

The porous body layer thus formed was impregnated with the Nafion solution again, cured at room temperature (20 ° C.) for 12 hours, and then cured by heating at 80 ° C. for 24 hours and further at 120 ° C. for 10 minutes. Filled with conductive electrolyte.
Further, a small amount of a binder solution obtained by mixing 5 parts by weight of a Nafion solution with respect to 95 parts by weight of the precursor solution was applied to the upper surface, and then a solvophilic gas diffusion electrode sheet was laminated, followed by 24 hours at 80 ° C. After curing, an MEA was formed by heating and pressing at 120 ° C.

  According to this method, since the porous body layer is formed directly on the gas diffusion electrode sheet, when the porous body layer is formed, the porous material layer is formed without contacting foreign substances at the interface between the electrode and the proton conductive membrane. And contamination of the interface is also prevented. Further, since the diffusion electrode itself is used as the substrate without using a substrate separately, a highly reliable fuel cell can be formed with good workability.

  In addition, two gas diffusion electrode sheets having a surface with a controlled polarity are formed, and one is used as a base, and a precursor solution for forming a porous body is applied to the surface of the base to heat and cure the porous body. Prior to filling the electrolyte and using the other as a lid, the contact angle is 30 degrees or less, heating and causing the condensation reaction, so that the joining reaction can be achieved together with the condensation reaction. Is possible.

According to this method, a gas diffusion electrode sheet having a solvophilic surface can be directly disposed on both surfaces of the porous body and cured by heating, thereby forming an MEA with good workability and good interface characteristics. It becomes possible.
Here, the method for treating the surface of the substrate is not particularly limited, and hydrophilicity by corona treatment is suitably used for making the solvent solvable when a polar solvent such as alcohol is selected as the solvent. . In addition, introduction of a polar group by plasma treatment, hydrophilization with a solvophilic resin, or the like can be used. At this time, a method of selecting a PET film, a fluororesin film, or the like is preferably used for solvent repellency. In addition, water repellent treatment by bringing a fluorine compound or silicon compound into contact, introduction of a hydrophobic group by plasma, a method of coating a fluorine resin, a silicone resin, or the like can be used.

  Similarly, when a nonpolar solvent is selected as the solvent, an appropriate treatment may be performed.

Hereinafter, examples of the porous membrane will be described.
(Example 1)
First, the synthesis of a crosslinkable precursor used for forming a porous body will be described.
(Synthesis of bifunctional precursor)
To a toluene solution of 11.0 g of 1,7-octadiene (manufactured by Wako Pure Chemical Industries) and 26.9 g of diethoxymethylsilane (manufactured by Shin-Etsu Silicon Co., Ltd.), chloroplatinic acid (manufactured by Wako Pure Chemical Industries) and divinyltetramethyldisiloxane ( 0.05 mmol of a Karsted catalyst (Karsted: USP3775452) solution prepared from Gelest Co. was mixed and stirred for one day in a nitrogen atmosphere at 30 ° C. The reaction mixture thus obtained was purified by distillation to obtain 1,8-bis (diethoxymethylsilyl) octane. The structure was confirmed by ¹ H-NMR.

(Synthesis of monofunctional precursor)
1,8-bis (dimethylethoxysilyl) octane was obtained in the same manner as in the bifunctional precursor synthesis step except that dimethylethoxysilane was used instead of diethoxymethylsilane. The structure was confirmed by NMR.

  Then, 0.73 g of 1,8-bis (diethoxymethylsilyl) octane, which is a bifunctional precursor formed by the above-described process, and 1,8-bis (dimethylethoxylyl) octane, which is a monofunctional precursor. 61 was dissolved in 1.2 ml of isopropanol to form an isopropanol solution.

  Meanwhile, 0.28 g of 8N hydrochloric acid was added to 1.2 ml of isopropanol. Both of these were combined and stirred for several tens of seconds to form a precursor solution. This precursor solution was applied to the surface of a substrate by a bar coater cast method on the surface of a corona-treated PET film having a contact angle with isopropanol of 5 degrees, covered with a 20 × 30 mm plastic case lid, and then brought to room temperature (20 ° C.). And then cured at 80 ° C. for 24 hours and further at 150 ° C. for 24 hours to form a white and elastic porous film having a thickness of 50 μm.

Here, the contact angle was measured by a usual method. The porosity and pore diameter of this porous film were measured with a porometer, and the inside and surface structure were observed with an SEM. The average pore diameter was 500 nm, the porosity was 70%, and the surface aperture ratio on the PET film side surface was 30%. It was confirmed that a continuous pore structure was formed.

The contact angle can be measured using a normal method, but the dynamic contact angle measurement method using the Wilhelmy plate method or the like (all new polymer experimental studies Volume 10: Physical properties of polymers (3) Kyoritsu Publication) is applicable.
There are various other methods for measuring the contact angle. For example, the method of JIS R3257 can be applied.

  2A and 2B are cross-sectional electron micrographs, and FIGS. 5A and 5B are photographs of the upper surface and the lower surface. It has a connected continuous pore structure and has openings on both surfaces.

In this way, it is possible to adjust the porosity while maintaining the mechanical strength of the membrane and obtain a continuous pore structure with a high porosity. According to this configuration, a porous body having heat resistance, flexibility, and dimensional stability can be obtained. By filling the pores with a proton conductive material, heat resistance, dimensional stability, flexibility A proton conductive membrane for fuel cells having both properties and mechanical strength can be obtained.
Moreover, it is not limited to a proton conductive membrane, Various functional membranes can be obtained by filling with other functional materials.

Also, the dielectric constant is sufficiently low.
In addition, when used as an interlayer insulating film, one having openings on both sides can be used, but as described above, as shown in FIGS. 4A and 4B, the contact angle is 30 degrees. By selecting the solvent so as to exceed, it is possible to have a structure in which both sides are closed. Since the dielectric constant can be reduced to about 1.9, it is possible to provide a semiconductor device capable of being driven at high speed while suppressing the parasitic capacitance formed between the first layer wiring and the second layer wiring. It becomes.

In addition, although the process of mixing a precursor and a catalyst is performed in the range of the boiling point of a solvent from the freezing point of a solvent, it is 0 to 40 degreeC desirably. If the temperature is high, the reaction proceeds and handling becomes difficult. The precursor and the catalyst may be mixed while cooling.
The curing step is from 5 ° C to the boiling point of the solvent, preferably from 10 ° C to 40 ° C. If the temperature is too low, the reaction rate is slow and a continuous pore structure is not formed. If it is too high, the reaction proceeds fast and does not form a continuous pore structure.
Further, in the cross-linking immobilization reaction intended to further proceed the condensation reaction and evaporate the solvent, the boiling point of the solvent is 300 ° C. or lower, preferably 100 to 200 ° C. If the temperature is too low, the crosslinking reaction is slow, and if it is too high, the organic part may be deteriorated.

  In the above examples, isopropanol was used as the solvent, but various solvents such as other alcohols or hydroalcoholic mixed solvents, water, and the like are applicable. In addition to ethylene glycol, a polymer that dissolves in a solvent such as polyethylene glycol, polyethylene oxide, polypropylene glycol, or polyvinyl alcohol may be added to the precursor solution as a phase separation regulator.

(Example 2)
Next, only the mixing ratio was changed in the same manner as in Example 1, and the trifunctional precursor 1,8-bis (triethoxysilyl) octane 0.43 g and the monofunctional precursor 1,8- 0.93 g of bis (dimethylethoxylyl) octane was dissolved in 1.3 ml of isopropanol to form an isopropanol solution.

  Meanwhile, 0.28 g of 8N hydrochloric acid was added to 1.2 ml of isopropanol. Both of these were combined and stirred for several tens of seconds to form a precursor solution. This precursor solution was applied to the surface of the substrate by a bar coater cast method on the surface of a PET film having a contact angle with isopropanol of 50 degrees, covered with a 20 × 30 mm plastic case lid, and then at 12 ° C. at room temperature (20 ° C.) After curing for a period of time, the film was heat-cured at 80 ° C. for 24 hours and then at 150 ° C. for 24 hours to form a white and elastic porous film having a thickness of 50 μm. The formed film was washed with a large amount of isopropanol, and then washed with a large amount of distilled water.

  When the porosity and pore diameter of this porous film were measured with a porosimeter, and the inside and surface structure were observed with an SEM, the average pore diameter was 500 nm, the porosity was 60%, and the results shown in FIGS. As shown, it was confirmed that a continuous pore structure having an opening ratio of 30% on one surface (upper surface) and an opening ratio of 0% on the back surface (lower surface) was formed.

  This porous film has a continuous pore structure in which pores are continuously connected inside, and has an opening on one surface and no opening on the other back surface.

  Since this porous film has a structure in which one side has an open area ratio of 0% and the open surface is closed, it is effective for use as an interlayer insulating film or the like. Even if water enters, the water entry stops on the closed surface, and the water is discharged from the side surface of the opening.

According to this configuration, a porous film having a low dielectric constant and having heat resistance, flexibility, and dimensional stability can be obtained.
In this case, since a porous film with one side closed is formed, it is effective as an interlayer insulating film as described above.
Further, by filling the pores with a functional material, various functional membranes such as a proton conductive membrane and an electrode can be obtained.

(Example 3)
Next, the same precursor solution as in Example 2 was formed, this precursor solution was applied to the same PET film surface as in Example 2, and the same PET film (thickness 50 μm) was further applied to the upper surface of this applied liquid. The film was coated with 13 cm, and leveled with an applicator having a coating thickness of 100 μm and a width of 15 cm.
This film was covered with a 20 × 30 mm plastic case lid, cured at room temperature (20 ° C.) for 12 hours, and then heat-cured at 80 ° C. for 24 hours and further at 150 ° C. for 24 hours. The formed film was washed with a large amount of isopropanol, and then washed with a large amount of distilled water. Thereafter, when the PET film was peeled off, a white and elastic porous film having a thickness of 50 μm was obtained.

When the porosity and pore diameter of this porous film were measured with a porosimeter, and the inside and surface structure were observed with an SEM, the average pore diameter was 80 nm, the porosity was 60%, and FIGS. 4 (a) and (b) Similarly, it was confirmed that a continuous pore structure having an opening ratio of 0% on both sides and a thickness of 50 μm was formed.
This porous film has a continuous pore structure in which pores are continuously connected inside, and has no opening on the front surface or the back surface.
According to this configuration, a porous body having heat resistance, flexibility, and dimensional stability can be obtained, which is effective as a low dielectric constant material. It is also effective as a heat insulating material having heat resistance.
This structure is a film having high moisture resistance and extremely good characteristics as an interlayer insulating film and a passivation film.

(Comparative Example 1)
In Example 1, a porous material was formed in the same manner as in Example 1 except that the precursor solution was formed using only 1.5 g of 1,8-bis (triethoxysilyl) octane.

  In this case, a transparent and hard film was obtained instead of the white elastic film. When the internal structure of this film was observed with an electron microscope, formation of a continuous pore structure could not be confirmed.

(Comparative Example 2)
In Example 1, a porous film was formed in the same manner as in Example 1 except that the precursor solution was formed using only 1.5 g of 1,2-bis (triethoxysilyl) ethane.

Also in this case, a transparent and hard film was obtained instead of the white elastic film. When the internal structure of this film was observed with an electron microscope, formation of a continuous pore structure could not be confirmed.
In this method, cracks occurred during handling, and sufficient evaluation as a self-supporting film could not be performed.
The porous membranes of Examples 1 and 2 and Comparative Examples 1 and 2 thus formed were evaluated.

The evaluation method was as follows.
(1) Evaluation of bending resistance The bending resistance of this porous body was measured by a bending resistance test (cylindrical mandrel method) described in JISK5600-5-1. A type I mandrel (diameter 10 mm) was used and evaluated according to the following evaluation criteria.
○ No cracks or cracks.
× There are cracks and cracks.
(2) Evaluation of heat resistance The porous body was heated for 5 hours in an autoclave at 140 ° C under saturated steam. The evaluation after heating was carried out by visual inspection, dimensional measurement, and bending resistance test, and the evaluation criteria were as follows. The results are shown in the following table. In all cases, there was no dimensional change and the rate of change (%) was zero.
○ Same as before implementation.
× Discoloration / deformation occurs.
Flexibility: Same as (1)

As is clear from the above results, according to Examples 1 to 3, a porous body having a continuous pore structure inside can be obtained, and both mechanical properties and heat resistance can be achieved. In particular, in the heat resistance evaluation at 140 ° C., the porous body formed by any of the methods of Examples 1 to 3 was hardly deformed, and extremely good results could be obtained.

  When used as a proton conductive membrane, acid groups were supplied to the porous body by the above-described method, and evaluation was performed by the following evaluation method.

(3) Proton conductivity evaluation The proton conductive membrane obtained by the production method of the present invention was set in a conventional electrochemical cell, and the proton conductive membrane and the platinum plate were brought into close contact with each other. The platinum plate was connected to an electrochemical impedance measuring device (1260 type, manufactured by Solartron), and impedance measurement was performed in a frequency range of 0.1 Hz to 100 kHz to evaluate the proton conductivity of the ion conductive membrane.

  In the above measurement, the sample was supported in an electrically insulated sealed container, and the cell temperature was changed from room temperature to 160 ° C. with a temperature controller in a water vapor atmosphere (95 to 100% RH). The proton conductivity was measured at

(4) Swelling ratio evaluation The proton conductive membrane obtained by the production method of the present invention was left to dry in a vacuum oven operated at 100 ° C. for 2 hours, and then the size of the obtained membrane was measured. The dry length was obtained (measured in diameter because it is mainly circular). Then, after immersing in 80 degreeC water and wiping off the surface water, the magnitude | size of the film | membrane was measured and what divided the changed length by dry length was made into the swelling rate.

  By introducing an acid group into the porous membrane formed by the method of Example 1 and introducing a proton conductive structure, a stable proton conductivity can be obtained at a high temperature, and the swelling rate is sufficient. It was low.

  As described above, the porous body of the present invention can adjust the porosity and the opening ratio of both front and back surfaces. The porous body is open on both sides, the porous body is open only on one side, and both sides are closed. Application to various functional membranes including fuel cell proton conductive membranes, electrodes, and columns, and devices using compound semiconductors such as HBT and semiconductor lasers, The present invention can also be applied to high-frequency devices such as microwave ICs, microwave transmission lines using film carriers or the like, or multilayer insulating substrates such as multilayer printed boards.

  In addition, this porous body having a continuous pore structure is particularly effective when applied to a device that easily breaks down, such as a compound semiconductor device, because it is particularly flexible and has a high effect as a buffer film.

  Furthermore, the porous body of the present invention is effective not only as a film but also as a bulk body or a tape-like body, which is adhered to an object.

It is a figure which shows the semiconductor device of embodiment of this invention. It is an electron micrograph of the porous body of embodiment of this invention. It is a manufacturing process figure of the semiconductor device of an embodiment of the invention. It is an electron micrograph of the porous body of embodiment of this invention. It is an electron micrograph of the porous body of embodiment of this invention. It is an electron micrograph of the porous body of embodiment of this invention. It is an electron micrograph of the porous body of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Insulating film 3 Gate oxide film 4 Gate electrodes 5a and 5b Low concentration impurity diffusion region (source / drain region)
6a, 6b High concentration impurity diffusion region (source / drain region)
7 Interlayer insulation film 8 First layer wiring 9 Contact hole 10 Second layer wiring 11 Passivation film

Claims (26)

Having a cross-linked structure by a metal-oxygen bond, having a continuous pore structure in which pores formed by the cross-linked structure are continuously connected,
A porous body, wherein at least the pores open on one main surface side of the porous body. 2. The porous body according to claim 1, wherein the pores are opened on both surfaces of the porous body.   2. The porous body according to claim 1, wherein the pores are opened on one surface of the porous body and closed on the other surface. Having a cross-linked structure by a metal-oxygen bond, having a continuous pore structure in which pores formed by the cross-linked structure are continuously connected,
A porous body characterized in that at least the pores are closed on both sides of the porous body.   The porous body according to any one of claims 1 to 4, wherein the continuous pore structure is in a range of porosity of 40 to 80%.   The porous body according to any one of claims 1 to 5, wherein the continuous pore structure has an average pore diameter in the range of 0.001 to 1 µm. The porous body according to claim 1, which has a structure represented by the following formula (1).

(In the formula, M is a metal or silicon, x is an —O— bond or OH group involved in crosslinking, R ¹ is a carbon atom-containing molecular chain group having 1 to 50 carbon atoms, and R ² is methyl or ethyl. , Propyl, or phenyl group, n ₁ , n ₂ are either 0, 1, or 2, and at least one of n ₁ , n ₂ is 1 or 2)   The porous body according to claim 7, wherein M is silicon. The porous body according to claim 7, wherein R ¹ in the formula (1) is a hydrocarbon group. The porous body according to claim 9, wherein the hydrocarbon group is a structure represented by the following formula (2).

  The porous body according to claim 10, wherein n in the formula (2) is in the range of 1-20. 12. The porous structure according to claim 9, wherein R ¹ in the formula (1) is octamethylene, R ² is a methyl group, and the structure is represented by the following formula (3). Body.

(Wherein x is an —O— bond or OH group involved in crosslinking, n ₁ and n ₂ are either 0, 1, or 2, and at least one of n ₁ and n ₂ is 1 or 2. Is) Preparing a mixture comprising a metal-oxygen bond crosslinkable material, a solvent, and a catalyst;
Supplying the mixture onto a substrate;
A step of forming a porous body having a continuous pore structure in which the mixture is subjected to a sol-gel reaction on the substrate and has a crosslinked structure by a metal-oxygen bond, and pores formed by the crosslinked structure are continuously connected. A method for producing a porous body comprising:
Prior to the step of supplying the mixture onto the substrate, the composition of the mixture or the surface state of the substrate is adjusted so that the open state of the pores at the interface between the porous body and the substrate becomes a desired state. The manufacturing method of the porous body characterized by including the process to adjust.   14. The substrate surface is made solvophilic so that phase separation between the polymer produced by the sol-gel reaction and the solvent occurs on the substrate surface prior to the supplying step. The manufacturing method of the porous body as described in 1 ..   The method for producing a porous body according to claim 14, wherein a contact angle of the solvent with respect to the surface of the substrate is 30 degrees or less.   Prior to the supplying step, the surface of the substrate is made to be solvent repellent so that phase separation between the polymer produced by the sol-gel reaction and the solvent does not occur on the surface of the substrate. 14. The method for producing a porous body according to 13.   The method for producing a porous body according to claim 16, wherein the contact angle of the solvent with respect to the surface of the substrate exceeds 30 degrees.   After the supplying step, prior to the step of forming the porous body, the method includes a step of bringing a substance having a contact angle with the solvent larger than 30 degrees into contact with the surface facing the substrate. The method for producing a porous body according to any one of claims 13 to 17.   After the supplying step, prior to the step of forming the porous body, the method includes a step of bringing a substance having a contact angle with the solvent of 30 degrees or less into contact with the surface facing the substrate. The method for producing a porous body according to any one of claims 13 to 17. The step of preparing the mixture is a step of preparing a mixture containing a plurality of crosslinkable silyl groups and an organic-inorganic composite crosslinkable compound having a carbon atom covalently bonded thereto.
Depositing the mixture on a substrate;
The method for producing a porous body according to any one of claims 13 to 19, further comprising a step of hydrolyzing / condensing the crosslinkable silyl group to form a porous body having a continuous pore structure. . The base is a semiconductor substrate having a desired element region and a wiring layer;
21. The method for manufacturing a porous body according to claim 13, further comprising a step of performing a hydrophobic treatment on the surface of the semiconductor substrate prior to the step of supplying the mixture.   Prior to the step of supplying the mixture, a gas diffusion electrode with a controlled surface polarity is prepared so as to have a solvophilic surface, and the gas diffusion electrode is used as a base, and an opening is formed on the gas diffusion electrode and its opposite surface side. 21. The method for producing a porous body according to claim 13, further comprising a step of directly forming the mixture on the gas diffusion electrode.   The porous body formed by the manufacturing method of the porous body in any one of Claims 13 thru | or 22.   Gas diffusion after introducing a proton conductive group into the pores of the porous body according to any one of claims 1 to 12, 22 and 23, or supplying a proton conductive electrolyte to the surface of the porous body. A method of manufacturing a fuel cell, comprising forming electrodes on both sides. Prior to the step of supplying the mixture using the method for producing a porous body according to claim 24,
First and second gas diffusion electrodes with controlled surface polarity are prepared so as to have a solvophilic surface, one of the first gas diffusion electrodes is used as a base, and the mixture is directly used as the first gas diffusion electrode. Supplying on the electrode,
Prior to the condensation of the mixture, a proton conductive group is introduced into the first gas diffusion electrode supplied with the mixture or a proton conductive electrolyte is formed on the surface of the mixture, and then the mixture is supplied. A method of manufacturing a fuel cell comprising the step of bringing the second gas diffusion electrode into contact with the surface of the first gas diffusion electrode and completely curing the surface.   27. A fuel cell using a membrane-electrode assembly (MEA) formed using the method for producing a fuel cell according to claim 25 or 26.

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