JP2005254094A - Method for manufacturing substrate with fine particles arranged on its surface, substrate manufactured by the method and article to which its surface structure is transferred - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a substrate with fine particles arranged on the surface, also a method capable of regularly arranging the fine particles on the substrate and a method for manufacturing a fine particle thin film highly accurately, in a large amount and continuously. <P>SOLUTION: The method for manufacturing the substrate arranging the fine particle on the surface is characterized by immersing the substrate in a suspension containing the fine particles and withdrawing the substrate from the suspension at a predetermined angle, thereby integrating the fine particles on the substrate. The fine particle can be accumulated in a monolayer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a substrate having fine particles arranged on the surface, a substrate having fine particles arranged on the surface produced by the method, and an article to which the surface structure of the substrate is transferred.

Conventionally, methods for aligning fine particles on a substrate include various optical materials such as interference films, reflection films, antireflection films, two-dimensional multi-lenses, and light control films, conductive films, electromagnetic shielding films, LSI substrates, and semiconductor lasers. It can be used in large-scale continuous manufacturing methods of fine particle thin films or fine particle crystallized films useful in various fields such as various electronic materials such as solid elements, optical recording media, magnetic storage media, photographic materials such as high-sensitivity photosensitive paper, and high-performance catalysts. This is a promising technology.
As a method of aligning the fine particles on the substrate, a spin coating method, a coating method, a dipping method, etc. are known as a dispersion method for obtaining a thin film of fine particles by drying and solidifying from a fine particle dispersion system such as an emulsion or a suspension. It is generally used practically.

However, in reality, in the case of the fine particle dispersion type thin film forming method such as the spin coating method, the coating method, and the dipping method, the thickness, the number of layers, and the fine particle density of the fine particle thin film are accurately and simultaneously controlled. It was difficult.
For example, the spin coating method can produce a very thin fine particle film, but has a drawback that the fine particle density is very difficult to control.
In addition, the coating method can increase the fine particle density, but usually has a drawback that only a very thick film of 10 μm or more can be formed.

As a method for solving such a drawback, a method of controlling the formation of a fine particle dispersed thin film has been proposed (see Patent Document 1).
Japanese Patent No. 2828386

  The present invention is a method of manufacturing a substrate in which fine particles are arrayed on the surface by a completely different principle as a solution to the problem of the thin film preparation method in the conventional dispersed thin film system, and the fine particles are regularly arranged on the substrate. The present invention provides a method that can be arranged, a substrate having a specific surface structure manufactured by the method, and an article to which the surface structure is transferred.

The present invention relates to the following.
1. A method for producing a substrate in which fine particles are arranged on a surface, wherein the fine particles are accumulated on the substrate by immersing the substrate in a suspension containing the fine particles and pulling the substrate from the suspension at a predetermined angle.
2. Item 2. The method for producing a substrate in which particles are arranged on the surface according to Item 1, wherein the particles are accumulated in a single layer.
3. Item 3. The method for producing a substrate in which particles are arranged on the surface according to Item 1 or 2, wherein the substrate is composed of a hydrophilic portion and a hydrophobic portion, and the particles are accumulated only in the hydrophilic portion.
4). Item 4. A substrate in which fine particles are arranged on the surface produced by the method according to any one of Items 1 to 3.
5). An article having a surface on which a surface microstructure of a substrate in which fine particles are arranged on the surface according to Item 4 is transferred.
6). A method for arranging fine particles, comprising immersing a substrate in a suspension containing fine particles, and arranging the fine particles on the substrate by pulling the substrate out of the suspension at a predetermined angle.

  According to the production method of the present invention, the fine particles can be easily arranged on the substrate, and can be regularly aligned particularly in a desired position and orientation, and the fine particle thin film can be produced in a large amount with high accuracy. Can be produced continuously. The substrate thus produced has fine particles arranged on the surface, and is useful as various functional substrates. Further, an article to which the surface structure of the substrate is transferred is also useful as having a functional surface. For example, it can be applied to a color material that has regular irregularities on the surface and uses light diffraction, or a product that is functionalized to hydrophilicity or super water-repellency.

First, a method for aligning fine particles on a substrate will be described.
FIG. 1 is a diagram showing an outline of a method for producing a substrate having fine particles arranged on the surface. In FIG. 1, the right figure is an enlarged view of a portion surrounded by a square in the left figure.
As shown in FIG. 1, the substrate 3 is immersed in the suspension 2 containing the fine particles 1, and then the substrate 3 is pulled out of the suspension 2 at a certain angle θ (see FIG. 1). At this time, since the capillary force acts near the water surface, the suspension 2 is attracted to the substrate 3, and as a result, the fine particles 1 are accumulated on the substrate 3. Since the film thickness of the attracted liquid gradually decreases, the fine particles 1 are integrated in a single layer. The angle θ is appropriately determined according to the state of integration, but is preferably selected from the range of 30 to 75 degrees. In the process of drying the liquid between the accumulated fine particles 1, the fine particles 1 are arranged at a higher density by the liquid crosslinking force acting between the fine particles 1.

  The fine particles 1 in the present invention preferably have an average particle size (diameter) of 0.3 to 1.5 μm, more preferably an average particle size of 0.992 to 0.994 μm. Resin is generally used as the material, and polystyrene fine particles having a uniform size and a specific gravity close to that of water are preferable. Examples of the fine particles include particles of thermoplastic resin such as polymethyl methacrylate in addition to polystyrene particles.

  The dispersion medium is preferably an aqueous medium such as water or a mixture of water and a water-soluble organic solvent such as acetonitrile. However, the present invention is not limited to these, and an organic solvent or other solvent may be used in some cases.

  The suspension 2 in the present invention is one in which the fine particles 1 are dispersed in water, and the fine particles 1 are preferably contained at a concentration of 0.1 to 10% by volume, more preferably 0.9 to 1. 1%. If necessary, a dispersing agent may be added to disperse the fine particles. The dispersant is preferably one that dissolves or disperses in an aqueous medium such as a water-soluble polymer colloid, a hardly soluble phosphate, or a surfactant. Examples of the water-soluble polymer colloid include cellulose derivatives such as polyvinyl alcohol, acrylonitrile, alkyl cellulose, and carboxyalkyl cellulose. Examples of the poorly soluble phosphate include tricalcium phosphate and magnesium phosphate. The dispersant is preferably used in an amount of 0.1 to 1% by weight based on the resin particles. It is preferable to use the surfactant in an amount of 0.005 to 0.5% by weight based on the resin particles. When using a poorly soluble phosphate as a dispersant, it is preferable to use an anionic surfactant such as sodium dodecylbenzenesulfonate at the same time.

  FIG. 2 shows an example of the substrate 3 composed of a hydrophilic part 4 and a hydrophobic part 5 when an aqueous medium is used as a suspension medium. The hydrophilic part 4 and the hydrophobic part 5 are adjacently arranged alternately. When such a substrate 3 is pulled out from the suspension 2 as described above, the suspension 2 is trapped in the hydrophilic portion 4, the fine particles 1 are arranged only in the hydrophilic portion 4, and the fine particles 1 are arranged in the hydrophobic portion 5. Absent.

In the present invention, as the substrate, a metal or other material such as silicon (for example, a silicon wafer) or iron (for example, an iron plate) can be used, and the shape is arbitrary, but it is easy to be immersed in the suspension. Shape is preferred.
FIG. 3 is an explanatory view showing a method of manufacturing the substrate 3 whose surface is composed of the hydrophilic portion 4 and the hydrophobic portion 5. A photosensitive resist 7 is uniformly applied on the silicon 6. In order to selectively irradiate the resist 7 with the UV light 9, the glass mask 8 is patterned so that the portion corresponding to the hydrophobic portion 5 passes the UV light 9, and the resist 7 is irradiated with the UV light 9 and developed. Then, the resist 7 corresponding to the hydrophobic portion 5 is peeled off. Furthermore, the hydrophobic material 10 was applied uniformly, the resist 7 was removed, and a hydrophilic treatment was performed on a portion corresponding to the hydrophilic portion 4 to produce a hydrophilic film 11.

  The hydrophobic material 10 in the present invention is a material having a contact angle of 90 to 150 degrees when water is gently dropped on a flat surface. In particular, poly (terafluoroethylene) (PTFE) is 104 to 105 degrees. Is preferably used.

In the present invention, the hydrophilic film 11 means that the silicon surface is oxidized and hydrophilized so that the contact angle is 20 degrees or less. In particular, a treatment called SPM treatment in which a ratio of sulfuric acid and water is appropriately adjusted is immersed for a predetermined time to convert the surface into SiO ₂ .

  In the present invention, the hydrophilic portion 4 and the hydrophobic portion 5 are adjacent and alternately arranged, but there is no particular limitation on the shape and arrangement thereof. For example, the hydrophobic portions 5 can be scattered and the hydrophilic portions 4 can be arranged continuously around the hydrophobic portions 5.

  FIG. 4 is a schematic explanatory view of the manufacture of an article to which the surface structure of the substrate 3 on which the fine particles 1 are aligned is transferred. The fine particles 1 on the substrate 3 fall as long as the substrate 3 is struck or shaken because the water molecules present at the interface between the substrate 3 and the fine particles 1 and the water molecules slightly present in the fine particles 1 act as a large adhesion force. In this state, the fine particles can be fixed by drying and solidifying by some method such as leaving or heating. In this way, a substrate having fine particles arranged on the surface can be used as the master product 12.

  In order to manufacture an article in which the surface state is transferred using the master product 12 as a mold, an electroforming method 13 is produced by faithfully inverting the surface of the master product 12 by using an electroforming method using nickel or copper as a raw material. By pressing and molding the resin material 14 with the electroforming mold 13, the surface of the electroforming mold 13 can be transferred to the resin material 14 and a product having the surface shape as obtained with the master product 12 can be manufactured. It is. The resin material 14 may be a thermoplastic resin such as polymethyl methacrylate or polycarbonate, or a thermosetting resin such as an unsaturated polyester resin or a phenol resin. Heating temperature and pressure vary depending on the product.

  First, the suspension 2 was dropped on the substrate 3 to examine the behavior of the fine particles 1 near the boundary between the hydrophilicity 4 and the hydrophobicity 5. FIG. 5 shows the method and results.

  The substrate 3 divided into the hydrophilic portion 4 and the hydrophobic portion 5 is formed by depositing PTFE on a silicon substrate by sputtering using an argon ion and applying the PTFE layer (thickness is 10 nm) to the hydrophobic portion. After that, the surface not covered with PTFE was surface-treated with dilute sulfuric acid.

  When the suspension 2 was dropped onto the boundary portion of the substrate 3 that was divided into the hydrophilic portion 4 and the hydrophobic portion 5, the suspension 2 was attracted from the hydrophobic portion 5 to the hydrophilic portion 4 by surface tension, and spread wet, The water was naturally dried (see FIG. 5 (a)). Here, a suspension (concentration 1%, particle size standard polystyrene manufactured by Duke Scientific Corporation) containing polystyrene fine particles having an average particle diameter (diameter) of 0.993 ± 0.021 μm was used. Moreover, it carried out in the clean room kept at the temperature of 20 degreeC and the humidity of 50%.

  As a result, it can be seen that the microparticles 1 are self-aligned along the boundary toward the hydrophilic portion 4 side, and the microparticle row is substantially linear (see the electron micrograph in FIG. 5B). In FIG.5 (b), the right photograph is an enlarged photograph of the part enclosed with the square of the left photograph. Therefore, it was found that the self-alignment position and orientation of the fine particles 1 can be controlled by arranging the hydrophilic portion 4 and the hydrophobic portion 5 in this way.

FIG. 6 is an electron micrograph showing the alignment state of the fine particles 1 on the substrate 3 according to one embodiment of the present invention. In FIG. 6, the right photograph is an enlarged photograph of a portion surrounded by a square in the left photograph.
The arrangement of the hydrophilic part 4 and the hydrophobic part 5 was 12 μm in pitch and 4 μm in width of the hydrophilic part 4. The pulling angle was 60 degrees and the pulling speed was 3.3 μm / s.
It can be seen that the fine particles 1 are aligned along the boundary line between the hydrophilic portion 4 and the hydrophobic portion 5 over a wide range.
Furthermore, since the alignment of the fine particles can be changed by changing the pulling angle and the pulling speed, the supply amount of the fine particles can be adjusted by adjusting the angle and the speed, and the alignment accuracy can be improved. it can.

Sectional drawing which shows the outline | summary of the manufacturing method of the board | substrate with which microparticles | fine-particles were arranged on the surface. The perspective view which shows the example of the board | substrate comprised by the hydrophilic part and the hydrophobic part. Explanatory drawing which shows the manufacturing method of the board | substrate comprised by the hydrophilic part and the hydrophobic part. Schematic explanatory drawing of manufacture of the article which transcribe | transferred the surface structure of the board | substrate with which microparticles | fine-particles were arranged. The schematic diagram and electron micrograph which show the test method and result of the alignment state of microparticles | fine-particles by dripping suspension. The electron micrograph which shows the alignment state of the microparticles | fine-particles on the board | substrate of one Example.

Explanation of symbols

1: Fine particle 2: Suspension 3: Substrate 4: Hydrophilic part 5: Hydrophobic part 6: Silicon 7: Resist 8: Glass mask 9: UV light 10: Hydrophobic material 11: Hydrophilic film 12: Master product 13: Electromold 14: Resin material

Claims (6)

A method for producing a substrate in which fine particles are arranged on a surface, wherein the fine particles are accumulated on the substrate by immersing the substrate in a suspension containing the fine particles and pulling the substrate from the suspension at a predetermined angle. 2. The method for producing a substrate having fine particles arranged on a surface according to claim 1, wherein the fine particles are accumulated in a single layer. 3. The method for producing a substrate with fine particles arranged on a surface according to claim 1, wherein the substrate comprises a hydrophilic portion and a hydrophobic portion, and the fine particles are accumulated only in the hydrophilic portion. A substrate having fine particles arranged on a surface produced by the method according to claim 1. 5. An article having a surface onto which a surface microstructure of a substrate having fine particles arranged on the surface is transferred. A method for arranging fine particles, comprising immersing a substrate in a suspension containing fine particles, and arranging the fine particles on the substrate by pulling the substrate out of the suspension at a predetermined angle.

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