JP2005089852A - Method for manufacturing micro structural body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of manufacturing a micro structural body with high aspect ratio, increasing the film thickness of the micro structural body and manufacturing the micro structural body of excellent durability and high quality at a low cost. <P>SOLUTION: By bringing a pattern with micro unevenness on a surface thereof into contact with treatment solution capable of depositing metal oxide therefrom, the metal oxide is deposited on at least a part of the micro unevenness. A filling material is filled on the surface with the micro unevenness of the pattern to integrate the metal oxide with the filling material, and the integrated filling material is released from the pattern. The micro structural body with high aspect ratio can be manufactured, and the film thickness of the micro structural body can be increased. The micro structural body of excellent durability which is worked by a high-temperature process can be manufactured at a low cost. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a microstructure.

  In fields such as various electronic materials, optical materials, and functional catalysts, technological development has been advanced with the aim of realizing new functions and enhancing functions that have never been achieved with nanometer-order fine structures.

As a method for producing a fine structure by transfer using a mold, the fine structure is obtained by immersing a mold having a fine structure in an aqueous solution, depositing an oxide on the mold, and then releasing the oxide. A liquid phase filling (Liquid Phase Infiltration: hereinafter referred to as LPI) method has been proposed. A technique is also known in which a mold having a fine structure is pressed against a polymer layer formed on a substrate to transfer the fine structure to the surface of the polymer layer.
S. Deki et al., "Liquid phase infiltration (LPI) process for the fabrication of highly nano ordered materials", 203rd Meeting of The Electrochemical Society, April 2003

  However, the LPI method is a method using an equilibrium reaction in a liquid phase, and a microstructure is gradually formed by the growth of metal oxide nuclei generated in the treatment liquid. For this reason, it is difficult to shorten the deposition time, and there is a problem that it takes a very long time when the aspect ratio of the fine structure is high or when the fine structure is thickened. Further, there is a problem that cracks are likely to occur in the fine structure as the aspect ratio and the film thickness are increased.

  In addition, the method of transferring the fine structure to the polymer layer has a problem that high-precision transfer is difficult because the polymer material undergoes volume shrinkage when cured. In addition, polymer materials are inferior in heat resistance and moisture resistance compared to inorganic materials, so when used as a material for optical communication equipment that requires durability, a temperature control mechanism is provided or hermetic packaging is used. Measures such as are necessary.

  The present invention has been made paying attention to such problems of the prior art. The purpose is to provide a technology that can produce a microstructure with a high aspect ratio and increase the thickness of the microstructure, and that can produce a high-quality microstructure at low cost with excellent durability. It is in.

  As a result of intensive studies, the inventors of the present invention have achieved that according to the present invention, the surface of fine irregularities provided on the mold is covered with a metal oxide and then filled with a filling material, thereby increasing the aspect ratio and the thickness of the film. It has been found that a fine structure can be obtained in a short time, a high-quality fine structure having sufficient strength can be produced at low cost, and the above object can be achieved.

  The manufacturing method according to claim 1, wherein the metal oxide is deposited on at least a part of the fine irregularities by bringing a mold having fine irregularities on the surface into contact with a treatment liquid capable of depositing metal oxides. The surface of the mold having fine irregularities is filled with a filling material, and the metal oxide and the filling material are integrated and peeled from the mold.

  The LPI method uses a so-called liquid phase precipitation method in which a metal oxide is precipitated from a liquid phase. The liquid phase precipitation method is a method in which a metal oxide is precipitated by a method such as shifting the equilibrium reaction of a metal complex in a solution, changing the solubility of a dissolved substance, or causing a dehydration condensation reaction in a solution. is there. Specifically, the metal oxide can be deposited by adjusting the temperature, concentration, and pH of the solution, or by adding a catalyst, a reaction initiator, or the like to the solution. Examples of the method for adjusting the concentration include a method of adding a substance that forms a stable compound with a ligand of the metal complex, a method of adding water to a supersaturated solution of the metal complex, and the like. Just choose.

    The liquid phase deposition method deposits a metal oxide from the liquid phase, so even when using a mold with a complicated shape, the mold and the substrate can be brought into contact with the liquid, and the metal oxide can be deposited with good controllability. It is a feature. Due to this excellent feature, the LPI method can obtain a high-order microstructure having not only a simple shape but also a complicated shape. Further, for example, by adding an additive material such as rhodamine or various organic materials into the treatment liquid, these additives can be introduced into the metal oxide film, It is also possible to increase the functionality.

  On the other hand, since the LPI method uses a liquid phase equilibrium reaction, when a thick film of 10 μm or more is obtained, it takes a very long time to completely deposit, and the frequency of occurrence of cracks and pinholes also increases. . On the other hand, when a thin film having a thickness of 10 μm or less is used, the deposition time is short. However, since the mechanical strength is small, the microstructure is destroyed at the time of release.

  In the above manufacturing method, even if the oxide portion is a thin film having a thickness of 10 μm or less, it is reinforced by the filling material, so that sufficient mechanical strength can be imparted so that the microstructure is not destroyed at the time of release.

  In addition, the fine structure and the substrate may be bonded and fixed after being filled with the filling material and before being released from the mold. As the substrate, any substrate may be used as long as it can adhere to the filler material such as Si, glass, ceramics, metal, and resin. Further, even a substrate made of a material that is not suitable for bonding with the filling material can be used by performing a surface treatment.

  Here, the material of the mold is not particularly limited, and may be appropriately selected from molds such as Si, glass, ceramics, metal, and resin according to the application.

  As a method for producing a fine structure in the mold, a method for obtaining a desired fine structure shape may be appropriately selected from lithography, laser processing, machining, and the like.

  The method for producing the mold is not particularly limited, and a replica mold obtained by filling a resin into a master mold made of Si, glass, ceramics, metal, or the like and releasing the filled resin may be used. Good.

  The fine irregularities provided in the mold may have any shape, and for example, a desired shape can be selected from fine shapes such as a hole shape, a protrusion shape, a groove shape, and a corrugated shape. In addition to repeating one type of shape pattern, a combination of two or more shapes or a random shape without a specific pattern may be used. The size of the fine irregularities is not particularly limited, and may be appropriately selected depending on the purpose.

  As a method of bringing the processing liquid into contact with the mold and the substrate, for example, any method such as a method of immersing the mold and the substrate in the processing liquid or a method of pouring the processing liquid between the mold and the substrate is used. Also good. When immersed in the treatment liquid, as long as the region where the metal oxide is deposited is in contact with the treatment liquid, a part of the mold or the substrate may not be immersed.

  Since the LPI method is a liquid phase process, the precipitated oxide is formed as nuclei in the initial stage, and the nuclei grow and become particles with time. In order to form a fine structure with high accuracy, it is desirable that the fine structure be formed from the precipitated oxide as early as possible. For this reason, it is possible to fill the fine irregularities with the deposited oxide in the initial stage by continuing to flow the treatment liquid until the surface of the fine irregularities of the mold is almost filled with the deposited oxide.

  The flow method is appropriately selected from known methods, for example, a method of continuing to flow the processing liquid, agitation of the processing liquid, rocking the one holding the mold and the substrate, and rocking the container. That's fine.

  However, bubbles are likely to accumulate in the uneven portions of the mold, and introduction of the treatment liquid into the fine uneven portions of the mold may be hindered by the bubbles. Therefore, it is possible to easily introduce the processing liquid into the fine irregularities by stirring the processing liquid, swinging while holding the mold and the fixed substrate, and swinging the container. The transferred microstructure can be formed with high accuracy. In addition, it is preferable to flow the treatment liquid and irradiate with ultrasonic waves because it is possible to efficiently remove bubbles.

  Furthermore, in order to facilitate the precipitation of oxides, it is preferable to perform a surface treatment on the mold. When the surface cleaning degree, surface activity, etc. are improved by the surface treatment, a fine structure can be formed with high accuracy.

  The filling material may be an inorganic material or an organic material, and may be appropriately selected depending on the purpose. Examples of the inorganic material include metals, metal oxides, calcium carbonate, and polymeric silicon compounds containing mineral fillers such as aluminum silicate and magnesium silicate. As the organic material, any material such as an inorganic / organic hybrid filling material such as a resin or a resin containing metal powder can be used. In addition, an inorganic material and an organic material can be used in combination, such as filling with a metal material first and then filling with a resin material.

  The mold release method is not particularly limited, and a known method may be used. For example, there are a method of physically peeling the mold and the substrate, a method of completely dissolving the mold with a solvent, or a method of peeling while melting. When physically peeling off, it is preferable to peel off air while gradually feeding air between the mold and the substrate because the fine structure can be peeled off without breaking.

  When the mold is dissolved with a solvent, for example, when a mold made of cellulose acetate is used, it can be dissolved with ethyl acetate or acetone. Moreover, when melt | dissolving, it can peel easily by applying physical force, such as ultrasonic irradiation and a rocking | fluctuation. When polystyrene, polyethyl methacrylate, or the like is used as a mold material, a 10: 1 mixed solution of ethyl bromide and benzene is used for polystyrene and chloroform and benzene are used for polymethacrylate as a solvent for dissolving the mold. A 1: 1 mixed solution may be used.

  The manufacturing method according to claim 2 is characterized in that the filling material is a metal.

  By using a metal as the filling material, the obtained microstructure can be heat-treated. By heat-treating the fine structure, impurities contained in the oxide can be removed, and a high-quality fine structure containing no impurities can be obtained. Further, the obtained fine structure can be used under high temperature and high humidity.

  The manufacturing method according to claim 3 is characterized in that the metal is deposited by a plating method.

  As a plating method, a generally known method such as an electroplating method or an electroless plating method can be used. The electroplating method is characterized in that it is easy to increase the plating rate as compared with the electroless plating method. On the other hand, the electroless plating method has good shape followability, has the characteristics that it can suppress defects such as pinholes and cracks, and can be plated on non-conductors. May be. In addition, by forming electroless plating as the first filling and then electroplating as the second filling, a fine structure is formed with high accuracy by the first filling, and a thick film is formed in a short time by the second filling. Can also be realized.

  The manufacturing method according to claim 4 is characterized in that the filling material is a resin.

  By using a resin as the filling material, a resin microstructure having a surface coated with a metal oxide can be obtained. Since the surface is coated with a metal oxide, durability against moisture, organic gas, and the like is higher than that of a fine structure made of only a resin material.

  As the resin material, any resin may be used as long as it has a viscosity that can be filled into the fine structure. Moreover, although there are various resin materials such as thermosetting and photocuring depending on the curing method, a resin having a hardness corresponding to the application may be used. For example, acrylic resin, polyester resin, epoxy resin, phenol resin, urea resin, fluororesin, polyester-urethane curing resin, epoxy-polyester curing resin, acrylic-polyester resin, acrylic-urethane curing resin, acrylic-melamine Curing resin or polyester-melamine curing resin, polyethylene resin, polypropylene resin, petroleum resin, styrene-acrylic copolymer, polyvinyl alcohol, polyacrylate, vinyl acrylate copolymer, maleic acid resin, polyamide resin, vinyl Resin, chlorinated rubber, cyclized rubber, ethylene-vinyl acetate copolymer resin, urethane resin, polyester resin, alkyd resin, resin mixture such as gilsonite, dammar or shellac, rosin modified phenolic resin, alkyd Butter, silicone resins, various fluorocarbon resins, urea resins, nitrocellulose, cellulose acetate, ethyl cellulose, and the like cellulose resins such as cellulose propionate.

  The manufacturing method according to claim 5 is characterized in that the resin is filled by a pressing method.

  As a resin filling method, a coating method, a spin coating method, a pressing method, and the like are known. Among these, the press method is preferable because it can forcibly remove bubbles in the resin. Moreover, the effect which suppresses a bubble can be improved more by pressing in a vacuum. It is also possible to bond the substrate made of Si, glass, ceramics, metal, resin, or the like to the resin portion as a backing material according to the application at the time of pressing.

  The manufacturing method according to claim 6, wherein the treatment liquid includes at least one metal selected from the group consisting of Si, Ti, Fe, Sn, Zn, V, Zr, W, and In and fluorine. Features.

The LPI method uses the liquid phase precipitation method as described above, but among the various precipitation methods, the method using the equilibrium reaction of the metal complex can deposit the metal oxide with the most controllability. It is. The metal complex is composed of a cation of a metal oxide to be filled and a ligand such as a halide or an amine, and may be selected depending on the application. Examples of the halide include F ⁻ , Cl ⁻ , ClO ₄ ⁻ , SO ₄ ²⁻ , OSO ₄ ^{4− and the} like. In particular, F ^- or the OSO ₄ ^4-a is used, preferably the control of the equilibrium reaction is facilitated, F ^- When using the, F ^- due to the strong oxidizing power of, that complexes of high oxidation number is obtained Since it can exist stably in a processing liquid as a fluoro complex, it is more preferable in terms of easy adjustment of the processing liquid.

  In the treatment liquid containing fluorine and metal M in claim 6, the equilibrium state shown in the following chemical formula 1 is established, and an oxide is precipitated by the reaction according to the following chemical formula 2 to form a fine structure. it is conceivable that. One or more metals M may be used.

(Chemical formula 1)
[MF _6-x (OH) _x ] ^2- + (6-x) H ₂ O ← → [M (OH) ₆ ] ^2- + (6-x) HF
(Chemical formula 2)
[M (OH) ₆ ] ² + 2H ⁺ → MO ₂ + 4H ₂ O

[M (OH) ₆ ] ^2- in Chemical Formula 1 is an unstable complex ion. By deliberately shifting the equilibrium reaction of Chemical Formula 1 toward the formation of [M (OH) ₆ ] ^2- , the chemical formula 2 causes the dehydration condensation reaction to precipitate an oxide represented by MO ₂ . When a treatment liquid containing a fluoro complex having fluorine as a ligand is used, an oxide having a dense structure can be easily obtained.

  As a method of intentionally shifting the equilibrium reaction of the above chemical formula 1, there is a method of adding a reaction initiator that easily reacts with HF to form a stable compound.

As reaction initiators, H ₃ BO ₃ , FeCl ₂ , FeCl ₃ , NaOH, NH ₃ , Al, Ti, Fe, Ni, Mg, Cu, Zn, Si, SiO ₂ , CaO, B ₂ O ₃ , Al ₂ from O ₃ and MgO may be selected at least one kind.

Even when any of the above reaction initiators is used, a stable fluoro complex compound or fluoride is generated in the treatment liquid, so that the precipitate is stably obtained without being inhibited. Among the reaction initiators, it is preferable to use a metal such as Al because the reaction rate with HF can be adjusted and the reaction can be controlled depending on the surface area of the metal. Further, it is more preferable to use H ₃ BO ₃ because precipitation of impurities is suppressed.

  As described above, according to the present invention, a fine structure having a high aspect ratio can be manufactured, and the fine structure can be made thick, and a fine structure having high durability and mechanical strength can be reduced. It can be manufactured at a low cost.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a diagram showing a cross-sectional structure of a microstructure in the present invention. A thin film layer of the metal oxide 2 is formed on the surface of the mold 1, and a layer of the filling material 3 is further formed thereon.

  The diffraction grating used as a mold was prepared by the following method. Photoresist was applied to a silicon substrate, and patterning was performed so as to form stripe openings with a period of 900 lines / mm. Using this photoresist as a mask, a groove having a depth of about 500 nm was formed on the surface of the silicon substrate by ion beam etching. The photoresist was peeled off and used as a master diffraction grating. An epoxy resin was press-molded on the master diffraction grating, adhered to a glass substrate, and then released to obtain an epoxy resin negative master diffraction grating. Next, a sol solution mainly composed of a solution obtained by hydrolyzing methyltriethoxysilane was applied onto a glass substrate by spin coating. Using the negative master diffraction grating (900 pieces / mm) as a pressing die, the sol solution on the glass substrate was press-molded, and released from the mold and then fired. This diffraction grating (900 lines / mm) was used as a mold.

  The microstructure of this example was manufactured by the following procedure. As the film forming treatment liquid, a liquid prepared to be 0.1 mol / L ammonium titanium fluoride and 0.2 mol / L boric acid was prepared. As shown in FIG. 2, the mold 1 was supported by the support member 5 and immersed in the treatment liquid 6. In order to efficiently introduce the treatment liquid between the microstructures, ultrasonic waves were irradiated after 1, 2, 3, 4 hours in the initial stage of immersion, and then the mold was pulled up from the treatment liquid after 8 hours and washed with pure water. After sufficiently drying, a commercially available epoxy resin was filled on the diffraction grating surface side coated with the oxide, and a glass substrate was bonded. After leaving it to stand for one day, the adhesive was completely dried and then released to obtain a fine structure on a glass substrate.

  In order to evaluate the adhesion to the substrate with respect to the obtained fine structure, a peel test that peels off vigorously after applying a cellophane tape (5 mm width) manufactured by Nichiban Co., Ltd. did not peel. It was confirmed that it has a sufficient degree of adhesion and a strength that does not break the shape. Moreover, it confirmed that the produced fine structure was a diffraction grating shape which has a pitch of 900 piece / mm.

  FIG. 4 is a flowchart showing a manufacturing process of a fine structure according to an embodiment of the present invention.

  In this example, a Si master mold having a square hole of 700 × 700 nm square and 500 nm depth by photolithography was used as a mold. A replica mold was prepared from the master mold using a replica film made of cellulose acetate.

  The microstructure of this example was manufactured by the following procedure. As a film-forming treatment solution, a solution prepared to be 0.1 mol / L ammonium titanium fluoride and 0.2 mol / L boric acid was prepared, and a replica mold was used using the same holding member as in Example 1. It was immersed in the processing solution. In order to efficiently bring the treatment liquid into contact with the fine structure, ultrasonic waves were irradiated after the initial immersion, 1, 2, 3, 4 hours, and after 8 hours, the mold was pulled out of the treatment liquid and washed with pure water. After sufficiently drying, a surface activation treatment was performed on the surface on which the microstructure of the mold was formed in order to impart catalytic activity as a pretreatment for electroless plating. Thereafter, the surface on which the mold microstructure was not formed was masked with a hydrofluoric acid resistant tape, and the masked replica mold was immersed in an electroless plating bath shown in Table 1.

(Table 1)
―――――――――――――――――――
Nickel sulfate 30g / L
Sodium hypophosphite 10g / L
Sodium acetate 30g / L
―――――――――――――――――――

  After 2 hours, the replica mold was pulled up, washed with pure water, and sufficiently dried. Next, a commercially available epoxy resin was poured into the plated surface side, and a glass substrate was bonded. After leaving it to stand for one day, the adhesive was completely dried and then released to obtain a fine structure on a glass substrate.

  When the above-described peel test was performed on the obtained fine structure, it was confirmed that the fine structure did not peel and had sufficient strength that the shape did not collapse. In addition, it was confirmed that the fabricated fine structure had a square hole with a 700 × 700 nm square and a depth of 500 nm.

  The fine structure manufacturing method according to the present invention integrates chemical analysis operations using optical technology fields such as optical sensors, information recording devices, and optical measuring devices, and catalysts, functional films, fine reactors, and fine flow paths. It can be applied to the field of chemical reaction / analysis such as μ-TAS (Micro Total Analysis System).

It is a figure which shows the cross-section of the fine structure in this invention. It is a figure which shows the liquid phase precipitation method in this invention. It is a flowchart which shows the manufacturing process in Example 2 of this invention.

Explanation of symbols

1: Mold 2: Oxide 3: Filling material 5: Support member 6: Treatment liquid

Claims (6)

  A surface having fine irregularities of the mold after depositing the metal oxide on at least a part of the fine irregularities by contacting a mold having fine irregularities on the surface with a treatment liquid capable of depositing metal oxides A manufacturing method of a fine structure, wherein a filling material is filled on top, the metal oxide and the filling material are integrated and peeled from the mold.   The method for manufacturing a microstructure according to claim 1, wherein the filling material is a metal.   The method for producing a microstructure according to claim 2, wherein the metal is deposited by a plating method.   The method for manufacturing a microstructure according to claim 1, wherein the filling material is a resin.   The method for producing a microstructure according to claim 4, wherein the resin is filled by a press method. 6. The process according to claim 1, wherein the treatment liquid contains at least one metal selected from the group consisting of Si, Ti, Fe, Sn, Zn, V, Zr, W, and In and fluorine. A manufacturing method of the fine structure according to claim 1.

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