JP4682888B2 - Method for producing ceramic ultrafine particle film - Google Patents

Description

  The present invention relates to a manufacturing method for forming a ceramic ultrafine particle film on a substrate surface.

  Patent Documents 1 and 2 are disclosed as methods for forming an inorganic oxide particle film on a substrate.

  Patent Document 1 is an invention related to a photonic crystal and a manufacturing method thereof, and a photonic crystal structure is manufactured by two kinds of methods. In the first method, a first functional group-modified particle layer and a second functional group-modified particle layer are individually laminated by chemical bonding between functional groups using a self-organized film. In the second method, the first functional group-modified particle layer and the second functional group-modified particle are dispersed in a solvent, and the particles are nucleated by chemical bonding between the two functional groups. FIG. 1 and FIG. 2 represent an image of forming a laminated structure of particle films by repeating these steps.

Patent Document 2 is an invention relating to a photocatalytic metal oxide pattern formation method, in which a hydrophilic pattern is formed by light irradiation after forming a film having a hydrophobic hydrophobic group (hydrophobic film) on a substrate. . In this method, the hydrophilic and hydrophobic coexisting substrate is immersed in a hydrolyzable metal oxide precursor solution and then reacted in a hydrolyzing atmosphere to deposit a metal compound on the hydrophilic pattern. FIG. 3 shows an image of this manufacturing process.
JP 2002-341161 A JP 2002-169303 A

  However, in the method disclosed in Patent Document 1, bond defects due to functional group modification are likely to occur and affect the lamination, so that it is difficult to form a particle film with a large area. For the same reason, there is no regularity in the particle structure, resulting in random deposition.

  Moreover, in the manufacturing method shown by patent document 2, since it is a metal oxide film obtained from the hydrolyzable metal oxide precursor liquid adhering on a board | substrate, there is no regularity in a particle arrangement and the packing density of particle | grains is There was a problem that it could not be raised.

  On the other hand, the invention of the present application intends to realize a regular array structure using ceramic ultrafine particles (ceramic nanoparticles having a diameter of 100 nm or less), and conventional ceramic fine particles (ceramic particles having a diameter of several hundred nm to 1 μm). Thus, a film having a novel functionality that cannot be obtained by the method is obtained.

This invention is inspired by a regular structure composed of organic and inorganic substances existing in nature, such as “natural opalite” mainly composed of SiO ₂ and “pearl” mainly composed of CaCO _3. An attempt is made to artificially form an ordered structure of ultrafine particles. In addition to imitating such a regular structure in the natural world, it is intended to be formed under normal temperature and normal pressure which is friendly to the natural environment.

  In order to form a ceramic ultrafine particle film on the surface of the substrate, it is important to adsorb the ceramic ultrafine particles on the substrate by an appropriate method.

Conventional general methods for adsorbing particles on a substrate include (1) a method based on electrostatic adsorption and (2) a method in which a substrate treatment agent and particles are covalently bonded.
However, the film of ceramic ultrafine particles after adsorption onto the substrate maintains the interaction between ceramic ultrafine particles and the adsorption / desorption equilibrium, and the state of the particles of the film is between particles due to the particle-substrate interaction. Largely affected by interaction.

  That is, in the method (1) based on electrostatic adsorption, the interaction (adsorption force) between particles on the substrate surface is too large and aggregates, and a single particle film with a high filling rate cannot be formed.

  In addition, in the method of (2) the substrate treating agent and the interparticle covalent bonding method, a particle film having a relatively good density can be formed with a certain limited material. For example, a PVP (polyvinyl polymer) compound is used as the substrate treating agent. If used, the thick (non-molecular level) polymer layer will be interposed between the substrate surface and the particles, and therefore generally the polymer layer must be removed by post-treatment.

  Accordingly, an object of the present invention is to produce an ordered single particle film of ceramic ultrafine particles by bringing the ceramic ultrafine particles close to the substrate surface with an electrostatic force and fixing them by chemical bonding.

  Specifically, the substrate is immersed in at least two kinds of organic compound solutions, and the surface potential of the substrate is opposite to the zeta potential of the ceramic ultrafine particle dispersion solution and is shared with the ceramic particles in the ceramic ultrafine particle dispersion solution. A surface potential control step for controlling the potential to allow bonding; a step of immersing the substrate in the ceramic ultrafine particle dispersion; and a step of drying the substrate.

  The surface potential control step includes a first treatment of immersing the substrate in a first silane compound solution having a chemical molecular formula represented by R-Si-X (R is a hydrocarbon group, X is a Cl or alkoxy group). And a chemical molecular formula (RO) n-Si-Ym (R is a hydrocarbon group, Y is an amino group, a mercapto group, an amine group, or a carboxyl group, and n = 1 -3, m = 1-3) and a second treatment step of immersing the substrate in a second silane compound solution.

  Specifically, the substrate is immersed in the first organic compound solution, and the substrate is irradiated with ultraviolet light so that the surface potential of the substrate has a polarity opposite to the zeta potential of the ceramic ultrafine particle dispersion solution. A surface potential control step of controlling the potential to be capable of covalently bonding with ceramic particles in the ceramic ultrafine particle dispersion solution, a step of immersing the substrate in the ceramic ultrafine particle dispersion solution, and a step of drying the substrate. Prepare.

  The surface potential control step includes immersing the substrate in a first silane compound solution represented by a chemical molecular formula R-Si-X (R is a hydrocarbon group, X is a Cl or alkoxy group). The first processing step and the second processing step of irradiating ultraviolet light subsequent to the first processing step.

The ceramic ultrafine particle film is any one of a SiO ₂ ultrafine particle film, a TiO ₂ ultrafine particle film, and a BaTiO ₃ ultrafine particle film. When the ceramic ultrafine particle film is an SiO ₂ ultrafine particle film or a TiO ₂ ultrafine particle film, the surface potential is, for example, 3.1 to 5.7 V, and the contact angle of the surface of the substrate is 90 °. The following.

  According to the present invention, in the surface potential control step, the surface potential of the substrate becomes a potential that can be covalently bonded to the ceramic ultrafine particles with a polarity opposite to the zeta potential of the ceramic ultrafine particle dispersion solution. Then, it can be brought close to the substrate and fixed by chemical bonding, and as a result, an ordered single particle film made of ultrafine ceramic particles can be obtained on the substrate.

  Further, as the surface potential control step, the surface potential of the substrate can be further increased by performing the first and second treatment steps of immersing the substrate in the first and second types of silane compound solutions. In addition, the filling rate of the ceramic ultrafine particles on the substrate can be increased.

  In addition, as the surface potential control step, the substrate is immersed in the first silane compound solution, and then a photochemical reaction is caused by irradiation with ultraviolet light, so that the surface potential of the substrate can be increased, and the ceramic superposition on the substrate can be increased. The filling rate of fine particles can be increased.

In addition, according to the present invention, a SiO ₂ ultrafine particle film, a TiO ₂ ultrafine particle film, or a BaTiO ₃ ultrafine particle film can be manufactured as the ceramic ultrafine particle film.

When the ceramic ultrafine particle film is a SiO ₂ ultrafine particle film or a TiO ₂ ultrafine particle film, the surface potential of the substrate is in the range of 3.1 to 5.7 V and the contact angle of the substrate surface is 90 ° or less. As a result, a regularly arranged single particle film of ceramic ultrafine particles on a substrate can be formed over a wide area with close packing.

(1) First, in order to remove dust and the like on the surface of the substrate on which the ceramic ultrafine particle film is formed, ultrasonic cleaning is performed with an organic solvent, followed by water washing and moisture removal.

(2) Next, the substrate is irradiated with ultraviolet light (UV light) using an excimer lamp to remove organic substances on the surface of the substrate to make it hydrophilic (dry cleaning).

(3) Next, the surface potential of the substrate is controlled. The surface electronic control of the substrate is performed by one of the following two methods.

(A) a first treatment step in which a substrate is immersed in a silane compound solution represented by the chemical molecular formula R-Si-X (R is a hydrocarbon group, X is a Cl or alkoxy group), and the first treatment step Then, the chemical molecular formula is (RO) n-Si-Ym (R is a hydrocarbon group, Y is an amino group, mercapto group, amine group or carboxyl group, n = 1-3, m = 1-3. And a second treatment step of immersing the substrate in a silane compound solution represented by

(B) a first treatment step in which the substrate is immersed in a silane compound solution represented by the chemical molecular formula R-Si-X (R is a hydrocarbon group, X is a Cl or alkoxy group), and the first treatment step. And a second treatment step of irradiating with ultraviolet light.

  Here, the silane-based compound is hydrolyzed when it comes into contact with water to generate a silanol group. These silanol groups are polymerized by self-condensation and at the same time hydrogen bond with OH groups on the substrate surface. On the other hand, the functional group R chemically bonds with the ceramic ultrafine particles.

(4) The substrate on which the surface potential has been controlled is dipped in a solution (suspension) in which ceramic ultrafine particles are dispersed and dried to form a ceramic ultrafine particle film on the substrate.

  FIG. 4 shows the results when two types of silane compound solutions corresponding to (a) (a) of the surface potential control of the substrate are used. (A) uses a trimethylchlorosilane solution (hereinafter referred to as “TMCS”) in the first treatment step and an aminopropyltriethoxysilane solution (hereinafter referred to as “APES”) in the second treatment step. The potential was 3.42 V and the contact angle was 50.4 °. (B) uses a chlorotrihexylsilane solution (hereinafter referred to as “CTHS”) in the first treatment step and an aminoethylaminopropyltrimethoxysilane solution (hereinafter referred to as “AAPMS”) in the second treatment step. The surface potential was 5.61 V and the contact angle was 36.0 °. (C) uses a chlorodimetalpinylsilane solution (hereinafter referred to as “CDMS”) in the first treatment step, and uses AAPMS in the second treatment step, the surface potential is 5.57 V, and the contact angle is It was 63.4 °.

  The TMCS, CTHS, and CDMS of the first silane compound solution used in the first treatment step are all represented by the chemical molecular formula R-Si-X (R is a hydrocarbon group, X is a Cl or alkoxy group). Silane-based compound solution. Further, APES and AAPMS of the second silane compound solution used in the second treatment step are both chemical molecular formulas (RO) n-Si-Ym (R is a hydrocarbon group, Y is an amino group, a mercapto group, It is a silane compound solution represented by either an amine group or a carboxyl group, n = 1-3, m = 1-3). Since the surface potential varies depending on the type and amount of the R group (hydrophobic group) of the silane compound adhering to the substrate surface, the resulting surface potential varies depending on the composition of the silane compound solution.

From this result, it can be seen that the higher the surface potential of the substrate, the more the SiO ₂ ultrafine particles are attached.

Here, as a comparative example, FIG. 5 shows the result when one kind of silane compound is used to control the surface potential of the substrate. (A) is a substrate immersed in octadecyltrimethoxysilane (hereinafter referred to as “OTS”), the surface potential is 0.64 V, the contact angle is 104.4 °, and (B) is the substrate immersed in CDMS. The surface potential was 1.15 V, and the contact angle was 51.4 °. (C) shows a substrate immersed in APES, surface potential is 2.58V, contact angle is 40.2 °, (D) is an example where a substrate is immersed in AAPMS, surface potential is 2.78V, The contact angle was 40.5 °. As described above, all the substrates immersed in one kind of silane compound solution have a small amount of SiO ₂ ultrafine particles attached thereto. As shown in FIG. 5D, even when the surface potential is 2.78 V, the degree of particle packing is still low.

  As described above, by immersing the substrate in two types of silane compound solution, the surface potential of the substrate is higher than that in the case of immersing in one type of silane compound solution shown in the comparative example. It can be seen that the higher the film thickness, the higher the degree of filling (close-packed film). This is because the surface potential of the first layer is lowered in the first treatment step by using two types of silane compound solutions and the substrate is immersed twice, and the organic compound of the second layer in the second treatment step. As a result, it is presumed that the surface potential of the substrate is increased due to adhesion of many organic compounds.

  FIG. 6 shows the results when the silane compound solution corresponding to (b) of the above-mentioned (3) substrate surface potential control and ultraviolet light irradiation are used. (A) was obtained by using OTS in the first treatment step and irradiating with ultraviolet light in the second treatment step. The surface potential was 4.22 V and the contact angle was 10 °. (B) is an example in which TMCS was used in the first processing step and ultraviolet light was irradiated in the second processing step. The surface potential was 4.35 V and the contact angle was 10 °.

  Thus, even when the substrate is immersed in one kind of silane compound solution, the surface potential is increased by combining it with ultraviolet light irradiation. This is presumed that the R group (hydrophobic group) molecules of the silane compound adhering to the substrate surface are cut by the photochemical reaction (activation) by ultraviolet light, and as a result, the surface potential is increased.

  Therefore, a close-packed ordered single-particle film of ceramic ultrafine particles over a wide area was obtained by combining ultraviolet irradiation after immersing the substrate in one kind of silane compound solution.

  From the above, it was found that an ordered single particle film can be obtained when the surface potential of the substrate is in the range of 3.1V to 5.7V. When attention is paid to the contact angle, a condition that the contact angle is 90 ° or less is also added.

  FIG. 7 shows the results of examining the influence of the zeta potential of the ceramic ultrafine particle dispersion (suspension). For the zeta potential shown here, a Zetasizer nano series (Nano-ZS) manufactured by Malvern was used.

FIG. 7 shows the state of the ultrafine particle film when the surface potential of the substrate is constant at 3.10 V and the zeta potential is changed. An SiO ₂ aqueous sol (manufactured by Nissan Chemical Industries, Ltd., trade name: STSOL) was used as the ceramic ultrafine particle dispersion solution, and after adjusting the concentration with water to change the zeta potential, an ultrafine particle film was formed. (A) is a SEM photograph of a film obtained when a ceramic ultrafine particle dispersion solution (STSOL stock solution) having a zeta potential of −22.4 mV is used. (B) is an SEM photograph of a film obtained when a ceramic ultrafine particle dispersion solution (solution of 10 times STSOL stock solution) having a zeta potential of −40.2 mV is used. (C) is an SEM photograph of a film obtained when a ceramic ultrafine particle dispersion solution (solution in which STSOL stock solution is diluted 20 times) having a zeta potential of −53.3 mV is used.

  Thus, it can be seen that the amount of ultrafine particles attached to the substrate surface increases by increasing the absolute value of the zeta potential of the ceramic ultrafine particle dispersion solution having the opposite polarity to the surface potential of the substrate.

  Here, as already described with reference to FIG. 6, since the surface potential can be controlled by irradiating with ultraviolet light in the surface potential control step, the ultrafine particle film is patterned by this ultraviolet light irradiation. Is also possible. 8 and 9 show an example thereof.

  FIGS. 8A and 8B show the results of performing line pattern ultraviolet light irradiation after the substrate was immersed in OTS. FIG. 8A is a wide-area SEM photograph, and FIG. 8B is an ultraviolet light irradiation region (b) of FIG. ) Is an enlarged SEM photograph of the ultraviolet light non-irradiated region (c) of (A).

  FIGS. 9A and 9B show the results of irradiating line pattern ultraviolet light after immersing the substrate in TMCS. FIG. 9A is a wide-area SEM photograph, and FIG. 9B is an ultraviolet light irradiation region (b) of FIG. (C) is an enlarged photograph of the boundary portion (c) between the ultraviolet light irradiation region and the non-irradiation region of (A).

  Thus, a dense ultrafine particle film is formed in the region irradiated with ultraviolet light, and no ultrafine particle film is formed in the region not irradiated.

All the examples shown above are for the SiO ₂ ultrafine particle film, but the same applies to the case of forming other ceramic ultrafine particle films. FIG. 10 shows an example of a TiO ₂ ultrafine particle film, in which the surface potential of the substrate is made constant at 3.10 V, and the zeta potential of the ceramic ultrafine particle dispersion containing TiO ₂ is changed. (A) is a case where the average zeta potential of the ceramic ultrafine particle dispersion is −29.6 mV, and a TiO ₂ ultrafine particle film having an average particle diameter of 17 nm was obtained. (B) shows the case where the average zeta potential of the ceramic ultrafine particle dispersion is −50.2 mV, and an ultrafine particle film having an average particle diameter of 40 nm was obtained. In this way, a dense ultrafine particle film can be formed on the entire surface of TiO ₂ as well.

FIG. 11 shows an example of a BaTiO ₃ ultrafine particle film, which is obtained when the surface potential of the substrate is adjusted to −0.03 V, and the zeta potential of the ceramic ultrafine particle dispersion containing BaTiO ₃ is +43.9 mV. It is a SEM photograph of the obtained film. As described above, with BaTiO ₃ as well, a dense ultrafine particle film can be formed on the entire surface of the substrate.

  In the above-mentioned range, only a single layer ultrafine particle film of ceramic ultrafine particles is formed on the surface of the substrate, but the present invention can be developed into a laminated structure of ceramic ultrafine particle films. For example, as shown in FIG. 12A, layers of nanoparticles A, B, and C are stacked on the substrate via the organic compound, and then the organic compound is removed by heat treatment or the like (B). Thus, a multilayer structure of ceramic ultrafine particle film is obtained.

In addition, if a multilayer structure is applied to produce an BT (BaTiO ₃ ) / ST (SrTiO ₃ ) cross-layered structure, for example, a new function compared with the bulk of BST ((Ba, Sr) TiO ₃ ) It is thought that sex will occur.

The method for manufacturing the ceramic ultrafine particle film according to the present invention has been described above, but various other modifications are possible.
For example, a silane-based compound solution is used as the organic compound solution, but the organic compound solution is not limited to this. At least two types of organic compound solutions are used, or the organic compound solution and ultraviolet light are used. Other organic compound solutions may be used as long as the surface potential can be controlled to a potential opposite to the zeta potential of the ceramic ultrafine particle dispersion solution and capable of covalent bonding with the ceramic particles in the ceramic ultrafine particle dispersion solution. Is possible.

  Two or more organic compound solutions may be used. In that case, it is necessary to lower the surface potential of the first layer in the first treatment step, and to easily adhere the organic compound in the subsequent treatment steps.

  In the following first to third examples, the following were used as the substrate and the ceramic ultrafine particle dispersion (suspension). First, as a substrate, a Si wafer (100 surface) subjected to the following surface treatment was prepared. The substrate was washed in an acetone solution for 10 minutes with an ultrasonic wave and replaced with ethanol, followed by washing with water, and water on the substrate was removed by heating at 150 ° C. for 5 minutes. Next, in order to remove organic components on the substrate surface, ultraviolet light irradiation was performed for 30 minutes or more with an excimer lamp.

As the ceramic ultrafine particle dispersion solution, a commercially available aqueous SiO ₂ sol solution (manufactured by Nissan Chemical Industries, Ltd., trade name: STSOL) was used. The aqueous SiO ₂ sol solution has a pH of 9 to 10, a zeta potential of −32.4 mV, and an average particle size of about 50 nm.

The surface potential of the substrate was measured using an AFM (Atomic Force Microscope). XPS (X-ray photoelectron spectroscopy) was used to detect the adhering elements. For hydrophilicity / hydrophobicity, the contact angle was measured using an interfacial tension meter. For measurement of the particle size, particle size distribution, and zeta potential of the aqueous SiO ₂ sol solution, Zeta Sizer Nano Series (Nano-ZS) manufactured by Malvern was used. For the SEM observation, an FE-SEM (field emission scanning electron microscope) was used.

<< First Example >>
As the first treatment step for controlling the surface potential of the substrate, the substrate is immersed in TMCS (trimethylchlorosilane: (CH ₃ ) ₃ SiCl) 1 vol% toluene solution) that is the first silane compound solution for 10 minutes. After being taken out, it was heated at 120 ° C. for 5 minutes. As a result, the adhesion between the substrate and the molecular film of the first silane compound was improved.

Subsequently, as a second treatment step, the substrate is a 1 vol% toluene solution of APES (γ-aminopropyltriethoxysilane: HN (CH ₃ ) ₂ Si (OC ₂ H ₅ ) ₃ ), which is a second silane compound solution. It was immersed for 60 minutes, taken out and heated at 120 ° C. for 5 minutes.

After performing the first and second treatment steps, the substrate was immersed in an aqueous SiO ₂ sol solution for 30 minutes. After removal, it was rinsed with water and dried at 1 ° C. for 48 hours.

<< Second Embodiment >>
As a first treatment step for controlling the surface potential of the substrate, the substrate is placed in a 1 vol% toluene solution of CTHS (chlorotrihexylsilane: [CH ₃ (CH ₂ ) ₅ ] ₃ SiCl) which is the first silane compound solution. For 10 minutes, and after taking out, heated at 120 ° C. for 5 minutes. As a result, the adhesion between the substrate and the molecular film of the first silane compound was improved.

Subsequently, as a second treatment step, the substrate is made of AAPMS (aminoethylaminopropyltrimethoxysilane: NH ₂ C = ONH ₂ C ₃ H ₆ Si (OC ₂ H ₅ ) ₃ ) which is the second silane compound solution. It was immersed in a 1 vol% toluene solution for 60 minutes, taken out, and then heated at 120 ° C. for 5 minutes.

After performing the first and second treatment steps, the substrate was immersed in an aqueous SiO ₂ sol solution for 30 minutes. After removal, it was rinsed with water and dried at 1 ° C. for 48 hours.

<< Third embodiment >>
As a first treatment step for controlling the surface potential of the substrate, the substrate is immersed in a 1 vol% toluene solution of phenyltrichlorosilane (PTCS): C ₆ H ₅ Cl ₃ Si, which is the first silane compound solution, for 10 minutes. Then, after taking out, it was heated at 120 ° C. for 5 minutes. As a result, the adhesion between the substrate and the molecular film of the first silane compound was improved.

Subsequently, as a second treatment step, the substrate was irradiated with ultraviolet light for 60 minutes using an excimer lamp (wavelength 172 nm). The substrate after irradiation was immersed in an aqueous SiO ₂ sol solution for 30 minutes. After removal, it was rinsed with water and dried at 1 ° C. for 48 hours.

FIG. 13 shows the result of observing the obtained ultrafine particle film with FE-SEM. In the first to third examples, the surface potentials of the treated substrates were 3.42 V , 5.61 V , and 4.33 V , respectively. From the SEM photograph of the obtained ultrafine particle film, it was found that all of them were close-packed over a wide area and highly regular.

It is a figure which shows the image of the manufacturing method of the photonic crystal shown by patent document 1. FIG. It is a figure which shows the image of the other manufacturing method of the photonic crystal shown by patent document 1. FIG. It is a figure which shows the image of the pattern formation process of the metal compound shown by patent document 2. FIG. It is a SEM photograph of an ultrafine particle film when the surface potential of a substrate is controlled using two types of silane compound solutions. It is a SEM photograph of the ultrafine particle film when the surface potential of the substrate is controlled using one type of silane compound solution as a comparative example. It is a SEM photograph of the ultrafine particle film when the surface potential of the substrate is controlled using a silane compound solution and ultraviolet light. It is a SEM photograph of the ultrafine particle film showing the influence of the zeta potential of the ceramic ultrafine particle dispersion. It is a SEM photograph which shows the example of the patterning of the ultrafine particle film | membrane by irradiation of an ultraviolet light. It is a SEM photograph which shows the example of the patterning of the ultrafine particle film | membrane by irradiation of an ultraviolet light. Is a SEM photograph showing an example of TiO ₂ ultrafine particle film. BaTiO ₃ is an SEM photograph showing an example of a ultrafine particle film. It is a figure which shows the example of the laminated structure of a ceramic ultrafine particle film | membrane. It is a SEM photograph of the ultrafine particle film formed according to the first to third examples.

Claims (6)

The substrate is immersed in at least two kinds of organic compound solutions, and the surface potential of the substrate is opposite to the zeta potential of the ceramic ultrafine particle dispersion solution so as to be capable of covalent bonding with the ceramic particles in the ceramic ultrafine particle dispersion solution. A surface potential control step to control;
Immersing the substrate in the ceramic ultrafine particle dispersion solution;
Drying the substrate;
A method for producing a ceramic ultrafine particle film.   The surface potential control step includes a first treatment of immersing the substrate in a first silane compound solution having a chemical molecular formula represented by R-Si-X (R is a hydrocarbon group, X is a Cl or alkoxy group). And a chemical molecular formula (RO) n-Si-Ym (R is a hydrocarbon group, Y is an amino group, a mercapto group, an amine group, or a carboxyl group, and n = 1 The method for producing a ceramic ultrafine particle film according to claim 1, further comprising a second treatment step of immersing the substrate in a second silane compound solution represented by ˜3, m = 1 to 3). The substrate is immersed in an organic compound solution, and the substrate is irradiated with ultraviolet light, and the surface potential of the substrate is opposite to the zeta potential of the ceramic ultrafine particle dispersion solution, and the ceramic particles in the ceramic ultrafine particle dispersion solution A surface potential control step for controlling the potential to a potential capable of covalent bonding with
Immersing the substrate in the ceramic ultrafine particle dispersion solution;
Drying the substrate;
A method for producing a ceramic ultrafine particle film.   The surface potential control step includes a first treatment of immersing the substrate in a first silane compound solution having a chemical molecular formula represented by R-Si-X (R is a hydrocarbon group, X is a Cl or alkoxy group). 4. The method for producing a ceramic ultrafine particle film according to claim 3, comprising a step and a second treatment step of irradiating ultraviolet light subsequent to the first treatment step. Said ceramic ultrafine particle film, SiO ₂ ultrafine particle film, TiO ₂ ultrafine particle film or manufacture of ceramic ultra-particle film according to any one of BaTiO ₃ claims 1 to 4 is either ultrafine particle film, Method. It said ceramic ultrafine particle film is either SiO ₂ ultrafine particle film or TiO ₂ ultrafine particle film, the surface potential is in the range of 3.1～5.7V, and the contact angle of the surface of the substrate 90 The method for producing a ceramic ultrafine particle film according to any one of claims 1 to 4, wherein the temperature is not more than ° C.