JP5518406B2 - Method for producing fine particle array structure - Google Patents

Description

  The present invention relates to a fine particle array structure and a method for manufacturing the same, and more particularly to a technique for forming a fine particle array structure in which fine particles are gathered and regularly arranged on an inner wall of a groove formed in a substrate.

  As a method of collecting and regularly arranging fine particles having a particle diameter of several nm to several μm to form the arrangement structure, a method of individually manipulating the fine particles can be considered, but for industrial applications. It is realistic to use the self-organization phenomenon of fine particles. The self-organization phenomenon of fine particles means that when a fine particle suspension in which fine particles are suspended in a solvent is placed on a substrate and the solvent is evaporated, the film thickness of the solvent increases from the fine particle substrate. This is a phenomenon in which fine particles are successively collected individually by the flow of the solvent and the surface tension of the solvent accompanying the evaporation of the portion (meniscus tip) that has become small enough to fill the gap. For example, Patent Document 1 below describes a method for producing a fine particle thin film using such a self-organization phenomenon of fine particles.

  Conventionally, however, there has been accumulation of technology for forming a two-dimensional structure by forming an array of fine particles on a flat substrate. It is technically difficult to form an array aggregate of fine particles on the inner wall of a so-called microchannel structure called a microchannel having a depth of about several hundred nm to several hundred μm and a depth of about several μm to 1 mm. was difficult.

  In order to solve such a problem, the following Patent Document 2 describes a fine particle assembly method in which the number of fine particles in a fine particle suspension is adjusted to form an array aggregate of fine particles on the inner wall of a microchannel.

JP-A-7-116502 JP 2006-291303 A

  However, the technique described in Patent Document 2 is not a technique that is suitable for forming an array aggregate of fine particles only on a selected predetermined wall portion of the inner wall of the groove structure.

  Accordingly, an object of the present invention is to provide a technique for forming an array aggregate of fine particles only on a selected predetermined wall portion of an inner wall of a groove structure.

In achieving the above object, the present invention provides a fine particle array structure having the following constitution and a method for producing the same.
[1] A fine particle array structure in which fine particles are formed in a single layer or a plurality of layers only on a predetermined wall portion of a groove formed in a substrate.
[2] The fine particle array structure according to [1], wherein the substrate is selected from silicon, glass, alumina, ITO, plastic, or polycarbonate.
[3] The fine particle array structure according to [1] or [2], wherein the groove has a width of 0.1 to 100 μm and a depth of 5 to 600 μm.
[4] The fine particle array structure according to any one of [1] to [3], wherein the fine particles have a particle diameter of 1 nm to 5 μm.
[5] The material of the fine particles is gold (Au), silver (Ag), copper (Cu), platinum (Pt), aluminum (Al), palladium (Pd), nickel (Ni), cobalt (Co), etc. Metal, tin oxide (SnO ₂ ), zinc oxide (ZnO), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), FeO ₃ , CdO, SrTiO ₃ , CoO, Fe ₃ O ₄ , Cu ₂ O, MgO, _{MnO, Ag 2 O, in 2} O 3, WO metal oxides such as _3, or polystyrene, an organic polymer such as an acrylic resin [1] to fine particle arrangement structure according to any one of [4].
[6] A fine particle suspension obtained by suspending fine particles in a solvent is filled in the grooves of a substrate having grooves having a predetermined width and depth on the surface, and the solvent of the filled fine particle suspension is used. A method for producing a fine particle array structure in which the fine particles are arranged in a single layer or a plurality of layers to form an array aggregate of the fine particles on a wall portion of the groove by drying, wherein the fine particles are suspended. The meniscus tip portion of the solvent with respect to the groove wall portion moves only in the selected predetermined region of the groove wall portion, so that the fine particles are applied only to the selected predetermined wall portion of the groove. A method for producing a fine particle array structure, wherein an array aggregate is formed.
[7] By using the fine particle suspension in which the volume ratio of the fine particles to the solvent is a predetermined value as the fine particle suspension, the array of fine particles is arranged only on a predetermined wall portion of the groove. The method for producing a fine particle array structure according to [6], wherein a body is formed.
[8] After filling the groove with the fine particle suspension, the solvent of the filled fine particle suspension is dried under a predetermined temperature, humidity, and / or atmospheric pressure to thereby select the predetermined groove. [6] The method for producing a fine-particle array structure according to [6], wherein the fine-particle array aggregate is formed only on the wall portion.
[9] The groove is selected by making wettability of the wall portion other than the selected predetermined wall portion of the groove with respect to the solvent of the fine particle suspension smaller than that of the selected wall portion. The method for producing a fine particle arrangement structure according to [6], wherein the fine particle arrangement aggregate is formed only on a predetermined wall portion.
[10] By immersing the substrate so that at least a part of the groove is in contact with the fine particle suspension, the fine particle suspension is filled into the groove by capillary action, and then the substrate is pulled up to The method for producing a fine particle array structure according to any one of [6] to [9], wherein the substrate is dried.
[11] The method for producing a fine particle array structure according to any one of [6] to [10], wherein the substrate is selected from silicon, glass, alumina, ITO, plastic, or polycarbonate.
[12] The method for producing a fine particle array structure according to any one of [6] to [11], wherein the groove has a width of 0.1 to 100 μm and a depth of 5 to 600 μm.
[13] The method for producing a fine particle array structure according to any one of [6] to [12], wherein the fine particles have a particle diameter of 1 nm to 5 μm.
[14] The material of the fine particles is gold (Au), silver (Ag), copper (Cu), platinum (Pt), aluminum (Al), palladium (Pd), nickel (Ni), cobalt (Co), etc. Metal, tin oxide (SnO ₂ ), zinc oxide (ZnO), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), FeO ₃ , CdO, SrTiO ₃ , CoO, Fe ₃ O ₄ , Cu ₂ O, MgO, _{MnO, Ag 2 O, in 2} O 3, WO metal oxides such as _3, or polystyrene, an organic polymer such as an acrylic resin [6] to the fine particle arrangement structure according to any one of [13] Production method.
[15] The groove filled in the groove under the conditions set based on the following mathematical formula (1) so that the filling rate (ε) of the fine particles to the predetermined wall portion selected in the groove becomes a desired value. The method for producing a fine particle array structure according to any one of [6] to [14], wherein the solvent of the fine particle suspension is dried.

(In the above formula, V is the meniscus retraction rate [m / s], h is the particle alignment portion thickness [m], Je is the drying rate [g / m · s], l is the meniscus length [m], and φ is (The volume fraction [%] of the fine particles in the solution, β is a proportional constant, and ε is the filling rate [%].)

  According to the fine particle arrangement structure of the present invention, since the fine particles are formed in a single layer or a plurality of layers only on a predetermined wall portion of the groove formed on the substrate, for example, the groove side By arranging conductive metal oxide fine particles only on the wall surface and forming an array aggregate of the fine particles, an electrode of the metal oxide is formed, while gas is formed in the space formed by the grooves. The gas sensor can be used for a gas sensor or the like that is configured to enter and senses a gas in the gas by measuring a resistance value related to a current flowing between electrodes on both side walls of the groove.

  According to the method for producing a fine particle array structure of the present invention, a fine particle suspension in which fine particles are suspended in a solvent is filled in the groove of a substrate having grooves having a predetermined width and depth on the surface. A fine particle array structure in which the fine particle suspension is dried to form an array aggregate of the fine particles in which the fine particles are arranged in a single layer or a plurality of layers on the wall of the groove. In the manufacturing method, the meniscus tip portion of the solvent in which the fine particles are suspended with respect to the groove wall portion moves only in the selected predetermined region of the groove wall portion. Since the array of fine particles is formed only on the walls of the fine particles, the fine particles are formed by arranging the fine particles in a single layer or a plurality of layers only on the selected predetermined wall portions of the grooves formed on the substrate. An array structure can be easily manufactured. That.

  Further, in the method for producing a fine particle array structure of the present invention, the volume ratio of the fine particles to the solvent, the temperature, humidity, and pressure when the solvent of the filled fine particle suspension is dried, and the fine particle suspension. By adjusting the wettability of the liquid with respect to the solvent to a predetermined value, it is possible to easily control the region where the meniscus tip moves.

  Further, in the method for producing a fine particle array structure of the present invention, the volume ratio of the fine particles to the solvent, the temperature, humidity, and pressure when the solvent of the filled fine particle suspension is dried, and the fine particle suspension. By adjusting the wettability of the liquid with respect to the solvent to a predetermined value, the filling rate (ε) of the fine particles with respect to the predetermined wall portion selected in the groove can be easily controlled.

It is a conceptual diagram of the meniscus front-end | tip part of the solvent of fine particle suspension. It is a schematic diagram of the process of forming a groove | channel on a board | substrate by deep reactive ion etching (DRIE: Deep Reactive Ion Etching). It is the micrograph (a) of the groove | channel obtained by deep reactive ion etching (DRIE), and its schematic diagram (b). It is a schematic diagram which shows one aspect | mode of the method of filling fine particle suspension in the groove | channel of a board | substrate. It is the microscope picture (a) of the fine particle arrangement structure obtained by manufacture example 1, the partial enlarged photograph (b), and the schematic diagram (c) of the structure. It is the microscope picture (a) of the fine particle arrangement | sequence structure obtained by manufacture example 2, and the schematic diagram (b) of the structure. Results of observing the drying process of pure water filled in the groove of the substrate (immediately after starting drying (a), 12 seconds after starting drying (b), 26 seconds after starting drying (c), 120 seconds after starting drying (d)) FIG. 6 is a schematic diagram showing a mechanism of arrangement of fine particles on the side wall of a groove in Test Example 1. FIG. It is a schematic diagram which shows the relationship between the receding (movement) of the solvent and the contact angle at the three-party boundary interface of substrate / solvent / outside air. It is a graph which shows the relationship between the volume ratio with respect to the solvent of the microparticles | fine-particles in microparticle suspension, and a side wall particle deposition number. It is the microscope picture (a: side wall, b: bottom) which shows the result of having observed the fine particle arrangement structure when the humidity of outside air is 50%, and the schematic diagram (c: side wall, d: bottom) of those structures. . It is the microscope picture (a: side wall, b: bottom) which shows the result of having observed the fine particle arrangement structure when the humidity of outside air is 67%, and the schematic diagram (c: side wall, d: bottom) of those structures. . It is the microscope picture (a: side wall, b: bottom surface) which shows the result of having observed the fine particle arrangement structure when the humidity of outside air atmosphere is 90%, and the schematic diagram (c: side wall, d: bottom surface) of those structures. . A photograph (a) showing a state when water is dropped on a silicon substrate treated with a fluorocarbon film, and water is dropped on a silicon substrate treated with a sulfuric acid / hydrogen peroxide mixture (SPM). It is the photograph (b) which shows the state at the time.

  The fine particle array structure of the present invention is characterized in that the fine particles are formed in a single layer or a plurality of layers only on a predetermined wall portion of a groove formed in the substrate. The fine particle array structure of the present invention can be obtained by a method for producing a fine particle array structure described later.

  The material of the substrate in the fine particle array structure of the present invention is not particularly limited as long as it is a substrate capable of forming a fine groove structure, but silicon, glass, alumina, ITO, plastic, polycarbonate and the like can be preferably exemplified.

  The groove structure in the fine particle array structure of the present invention is preferably a fine groove structure having a width of about 0.1 to 100 μm and a depth of about 5 to 600 μm. By forming an array structure of fine particles on the inner wall of such a fine groove structure, it can be used for a reaction platform having a compact and integrated three-dimensional structure.

  As the fine particles in the fine particle array structure of the present invention, those having a particle size of about 1 nm to 5 μm, more preferably about 1 nm to 100 nm are used. This facilitates formation of an array structure of fine particles using a self-organization phenomenon described later. Further, the surface area per volume of the array structure can be increased, which is more suitable for a reaction platform having a compact and integrated three-dimensional structure.

The material of the fine particles in the fine particle array structure of the present invention is not particularly limited as long as it can constitute the fine particles, but gold (Au), silver (Ag), copper (Cu), platinum (Pt), Metals such as aluminum (Al), palladium (Pd), nickel (Ni), cobalt (Co), tin oxide (SnO ₂ ), zinc oxide (ZnO), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), Metal oxides such as FeO ₃ , CdO, SrTiO ₃ , CoO, Fe ₃ O ₄ , Cu ₂ O, MgO, MnO, Ag ₂ O, In ₂ O ₃ , WO ₃ or organic polymers such as polystyrene and acrylic resin Can be preferably exemplified.

  On the other hand, in the method for producing a fine particle array structure of the present invention, a fine particle suspension obtained by suspending fine particles in a solvent is filled in the groove of a substrate having grooves having a predetermined width and depth on the surface. A fine particle array structure in which the fine particle suspension is dried to form an array aggregate of the fine particles in which the fine particles are arranged in a single layer or a plurality of layers on the wall of the groove. In the manufacturing method, the meniscus tip portion of the solvent in which the fine particles are suspended with respect to the groove wall portion moves only in the selected predetermined region of the groove wall portion, so that the groove is selected. In addition, the fine particle array aggregate is formed only on a predetermined wall portion.

  In the method for producing a fine particle array structure of the present invention, the “meniscus tip” refers to the self-organization phenomenon of fine particles suspended in a solvent around the boundary between the solvent, the groove wall and the outside air. It means a predetermined portion of the solvent of the fine particle suspension that has become a state that can be caused. Here, it demonstrates with reference to FIG. FIG. 1 shows the state of the meniscus tip of the fine particle suspension 2 with respect to the wall 1 of the substrate groove. From the portion (indicated by “A” in the figure) where the film thickness of the solvent of the fine particle suspension 2 is reduced to the extent that the particle alignment portion thickness 4 due to the fine particles 2a is filled, the wall portion of the solvent and the groove. In the portion up to the front edge of the boundary between the atmosphere and the outside atmosphere (indicated by “B” in the figure), the fine particles 2 a are successively assembled individually by the solvent flow 3 accompanying the drying 7 and the surface tension of the solvent. . This portion (indicated by the length of the meniscus tip 5 in the figure) is the “meniscus tip”. With the drying 7, this “meniscus tip” retreats 6 downward in the figure and moves on the surface of the wall 1 of the substrate groove.

  In the method for producing a fine particle array structure of the present invention, the meniscus tip is moved only in a selected predetermined region of the groove wall so as to move to the selected predetermined wall of the groove. Only an array aggregate of the fine particles can be formed.

  In the method for producing a fine particle array structure according to the present invention, first, a substrate having a groove with a predetermined width and depth formed on the surface is prepared. A method for forming the groove of the substrate on which the groove is formed may be appropriately selected from materials suitable for the material of the substrate and the structure of the groove to be obtained, and is not particularly limited. For example, the material of the substrate is silicon. In this case, it can be performed by deep reactive ion etching (DRIE).

The deep reactive ion etching (DRIE) will be described with reference to FIG. 2. Sulfur hexafluoride (SF ₆ ) is applied to the substrate 10 provided with a predetermined opening 12 on the surface and covered with the protective mask 11. Etch in the vertical direction with plasma ions such as. The inner wall surface of the groove 13 formed by the etching is protected by a protective film 14 such as a Teflon-based gas (C ₄ F ₈ ). By repeating this etching and protective film forming step, a groove 13 is formed in the opening of the protective mask. By forming the protective film after the etching process, the protective film 14 is also formed on the bottom surface of the groove 13. In the next etching process, plasma ions of sulfur hexafluoride (SF ₆ ) are applied to the protective film 14 on the bottom surface. Etching in the vertical direction is recommended while removing by attack. On the other hand, since the plasma ion irradiation is weak in the lateral direction, the protective film 14 is not removed and the side wall surface is protected from etching.

  FIG. 3a shows an example of a micrograph of a groove obtained by deep reactive ion etching (DRIE). FIG. 3b shows a schematic diagram thereof. The shape of the side wall surface of the groove is a shape 15 called a scallop shape that is recessed in the left-right direction when viewed from the front of the figure, although it causes anisotropy by applying an electric field to the plasma. This is because lateral etching resulting from a chemical reaction occurs. In addition, the scalloped shape of the side wall surface of the groove shown in FIG. 3 is about 1 piece / μm per length in the depth direction of the groove, and the maximum depth of the dent for each step is about 500 nm. By adjusting the plasma ion irradiation time, it is possible to control the former in the range of 0.1 to 10 / μm and the latter in the range of 100 to 1000 nm.

  In the method for producing a fine particle array structure of the present invention, a fine particle suspension obtained by suspending fine particles in a solvent is prepared. The solvent to be used may be appropriately selected depending on the viscosity, the dispersibility of the fine particles, the wettability with respect to the substrate, etc., but generally, for example, water, ethanol, isopropyl alcohol (IPA), xylene, toluene and the like are exemplified. it can.

  In the method for producing a fine particle array structure of the present invention, a fine particle suspension obtained by suspending the fine particles in a solvent is filled in the grooves of the substrate on which the grooves are formed. There is no particular limitation on the method of filling the fine particle suspension, and the fine particle suspension can be placed by spraying, dropping, or the like on the groove and filling the groove with the fine particle suspension by capillary action. .

  In the method for producing a fine particle array structure of the present invention, the solvent of the fine particle suspension filled in the groove is dried. The drying method may be natural drying or may be performed under reduced pressure in order to promote evaporation of the solvent.

  Here, with reference to FIG. 4, an example of the preferable aspect of the process of the said filling and drying is demonstrated. Here, a substrate holding / moving device (not shown) including a support table on which a beaker can be placed and an arm that holds the silicon substrate and can move vertically is used. The container 20 containing the fine particle suspension is placed on a support (not shown) of the substrate holding and moving device. On the other hand, the silicon substrate 10 in which the groove is formed is held by an arm (not shown) of the holding and moving device for the substrate. The arm is moved downward while holding the silicon substrate, so that at least a part of the groove of the substrate is in contact with the fine particle suspension, and the arm is stopped at a predetermined position. In this state, the fine particle suspension 2 is filled in the groove of the substrate 10 by capillary action. Next, the arm is moved upward to pull up the substrate 10 from the fine particle suspension 2 and dry it indoors or in an outside air atmosphere in which temperature, humidity, pressure, etc. are controlled. By performing the above operation by installing the substrate holding and moving device in a temperature-controlled room, it becomes easy to dry the substrate under a controlled outside air atmosphere such as temperature, humidity, and atmospheric pressure.

  At this time, in order to uniformly fill the grooves of the fine particle suspension, it is preferable that the length direction of the grooves is the same as the direction in which the silicon substrate is moved up and down, but the grooves are formed in other directions. Also good. In addition, the immersion time (the time from when the arm is stopped at a predetermined position to when it starts to move upward) can be performed in about 1 to 30 seconds, for example, and the lifting speed can be performed in about 1 μm to 20 mm / second, for example. it can.

  In the method for producing a fine particle array structure according to the present invention, as the solvent of the fine particle suspension is dried, the meniscus tip is moved only in a predetermined region of the groove wall. Examples of such an embodiment include the following.

(1) The volume ratio of the fine particles in the fine particle suspension to the solvent is adjusted.
That is, as shown in the examples described later, a fine particle suspension in which polystyrene beads are suspended in water is filled in a fine groove having a width of 50 μm and a depth of 100 μm formed on a silicon substrate, and is naturally dried at room temperature. First, the meniscus tip is generated on the side wall surface, and it moves in a certain region of the side wall surface. Therefore, an array aggregate of fine particles is formed in the region where the meniscus tip moves, and if the number of fine particles to be contained in the fine particle suspension is limited to a predetermined number, the fine particles that can form the aggregate are depleted. At the stage of depletion, fine particle array aggregates are not formed on the other side wall surface and bottom surface.

(2) Adjust the temperature, humidity, and / or pressure in the outside air atmosphere.
That is, as shown in the examples described later, when the humidity of the outside air atmosphere is lowered and the drying speed of the solvent at the meniscus tip is increased, self-organization of the fine particles is promoted. Therefore, if the drying rate is increased by adjusting the temperature, humidity, and / or pressure in the outside air atmosphere, the filling rate per region increases, and as the filling rate increases, fine particles are arranged from a single layer to multiple layers. become. On the other hand, as in the above (1), if the number of fine particles to be contained in the fine particle suspension is limited to a predetermined number, the fine particles that can form an aggregate are depleted. No array of fine particles is formed on the bottom surface. Therefore, the region where the array aggregate of fine particles is formed is more limited accordingly.

(3) Adjust the wettability of the groove wall to the solvent.
Desirable by adjusting the wettability of the fine particle suspension to the solvent on the wall portion other than the region where the fine particle array aggregate is formed so that the meniscus tip portion does not occur in the wall portion of the predetermined region. The array of fine particles can be formed only on the wall of the region.

  That is, as shown in the examples described later, for example, the water wettability of the wall portion subjected to the water repellent coating treatment is very small, and the water dries while maintaining a large contact angle with the wall portion. Therefore, the tip of the meniscus is not generated, and an array aggregate of fine particles is not formed.

  Therefore, for example, in the deep reactive ion etching (DRIE) described above, a water-repellent coating (fluorocarbon film) is applied as a protective film on the groove sidewall surface. Thereby, formation of the fine particle aggregate on the side wall can be prevented, and formation of the fine particle array aggregate in the other region (bottom surface) can be promoted.

  In the method for producing the fine particle array structure of the present invention, the groove is selected by drying the solvent of the fine particle suspension filled in the groove under the conditions set based on the following mathematical formula (1). The filling rate (ε) of the fine particles with respect to the predetermined wall portion can be controlled to a desired value.

(In the above formula, V is the meniscus retraction rate [m / s], h is the particle alignment portion thickness [m], Je is the drying rate [g / m · s], l is the meniscus length [m], and φ is (The volume fraction [%] of the fine particles in the solution, β is a proportional constant, and ε is the filling rate [%].)

  Here, the filling rate [%] is the volume of fine particles occupying per unit volume. The meniscus retracting speed [m / s] is the retracting speed (moving speed) of the meniscus tip as the liquid volume decreases. The particle alignment portion thickness [m] is the thickness of the deposited particle film. The drying rate [g / m · s] is the drying rate of the solvent. The meniscus length [m] is the length of the meniscus tip. The volume ratio [%] with respect to the solution of fine particles is the volume ratio with respect to the solution of fine particles in the fine particle suspension to be used. These parameters can be actually measured by observation with an electron microscope or the like. The proportionality constant β is a proportionality constant that correlates the above parameters.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, these Examples do not limit the scope of the present invention.

<Production Example 1> (Production of Fine Particle Array Structure 1)
A silicon substrate having a trench-like groove of 50 μm width × 100 μm depth × 10 mm length formed on the surface was obtained by deep reactive ion etching (DRIE) as described above.

  On the other hand, a substrate holding and moving device provided with a support table on which a beaker can be placed and an arm that can hold a silicon substrate and move vertically in the vertical direction was installed in a temperature-controlled room. A CCD microscope was placed beside the substrate holding and moving device so that the inside of the trench-like groove could be observed and recorded.

  A silicon substrate having a trench-like groove on the other hand, a container containing 6% by volume water suspension of polystyrene beads (manufactured by Thermo Fisher Scientific, particle size: 1 μm) placed on the support of the substrate holding and moving device. Is attached to the arm of the substrate holding and moving device, and is moved downward while holding the substrate so that at least a part of the groove of the substrate is in contact with the fine particle suspension. Stopped. In this state, the arm was moved upward at 5 mm / sec for 5 seconds, and the substrate was pulled up. With the substrate still attached to the arm, the substrate was allowed to stand for 10 minutes in a temperature-controlled room maintained at a temperature of 22 ° C. and a humidity of 55% to dry the water as the solvent for the fine particle suspension.

  FIG. 5a shows a micrograph of the obtained fine particle array structure. FIG. 5b shows a partially enlarged photograph of the micrograph shown in FIG. 5a. FIG. 5c is a diagram schematically showing the obtained fine particle array structure. As can be seen from these micrographs, it can be seen that an array of fine particles in which styrene beads are regularly arranged in a single layer is formed on the side wall inside the groove. On the other hand, it can be seen that an array aggregate of styrene beads is not formed on the bottom surface inside the groove.

<Production Example 2> (Production of Fine Particle Array Structure 2)
Using polystyrene beads of different particle sizes (0.5 μm) (Thermo Fisher Scientific, particle size 0.5 μm), water as a solvent of the fine particle suspension is dried in a temperature-controlled room maintained at a temperature of 25 ° C. and a humidity of 40%. Except for the above, a fine particle array structure was obtained in the same manner as in Production Example 1.

  FIG. 6a shows a micrograph of the obtained fine particle array structure. FIG. 6b is a diagram schematically showing the obtained fine particle array structure. As can be seen from these micrographs, it can be seen that an array of fine particles in which styrene beads are regularly arranged in multiple layers is formed on the side wall inside the groove.

<Test Example 1> (Consideration of Mechanism of Arrangement of Fine Particles into Selective Regions 1)
In each of Production Example 1 and Production Example 2, an array aggregate of fine particles was formed on the side wall inside the groove, but not on the bottom surface. Therefore, the mechanism of the sequence to this selective region was examined.

  Therefore, a silicon substrate having a trench-like groove having a width of 50 μm, a depth of 100 μm and a length of 10 mm formed on the surface was prepared in the same manner as in Production Example 1 and Production Example 2 above. Pure water was dropped and filled into the groove of the substrate, and the drying process of the pure water was observed with a CCD microscope.

  FIG. 7 shows micrographs of cross sections immediately after the start of drying (a), 12 seconds after the start of drying (b), 26 seconds after the start of drying (c), and 120 seconds after the start of drying (d). Moreover, the schematic schematic of the mechanism of the arrangement | sequence of microparticles | fine-particles considered from this result is shown to FIG.

  As shown in FIGS. 8a to 8d, in the production example 1 and the production example 2, the fine particles are selectively arranged on the side wall inside the groove. The wall portion of the groove of the solvent in which the fine particles are suspended is formed on the wall portion. It is thought that this is because a meniscus tip portion with respect to is not generated on the bottom surface.

  This will be further described with reference to FIG. 9 because the angle at which the boundary between the solvent, the wall of the groove, and the outside air atmosphere starts to recede (move) with the drying on the side wall inside the groove is sufficiently small. It was thought that a meniscus tip where fine particles self-assembled could occur (FIG. 9a). On the other hand, at the bottom surface inside the groove, as the drying, the angle at which the boundary between the solvent, the wall of the groove and the outside atmosphere begins to recede (move) does not become sufficiently small, so that the fine particles self-assemble. It was thought that no meniscus tip was formed (FIG. 9b).

<Test Example 2> (Consideration of Mechanism of Arrangement of Fine Particles into Selective Region 2)
It is known that the state parameter related to the meniscus tip and the fine particle filling rate (ε) per unit volume can be expressed by the following formula (1) (Basics of Modern Interfacial Colloid Chemistry, May 2002) March 15 The Chemical Society of Japan Maruzen Co., Ltd.).

(In the above formula, V is the meniscus retraction rate [m / s], h is the particle alignment portion thickness [m], Je is the drying rate [g / m · s], l is the meniscus length [m], and φ is (The volume fraction [%] of the fine particles in the solution, β is a proportional constant, and ε is the filling rate [%].)

  Then, the control factor which can be utilized in order to control the said filling rate was examined. As a result, it was considered that the particle alignment portion thickness h [m] can be controlled by wall roughness, solvent viscosity, substrate and solvent wettability, solvent surface tension, and the like. Further, it was considered that the meniscus receding speed V [m / s] and the drying speed Je [g / m · s] can be controlled by the temperature, humidity, atmospheric pressure, etc. of the outside air atmosphere. Further, it was considered that the volume ratio of the fine particles to the solution can be controlled in the fine particle suspension adjustment stage.

<Test Example 3> (Effect of volume ratio of fine particles on solvent)
It was examined how the volume ratio of the fine particles in the fine particle suspension to the solvent affects the filling rate per unit volume of the fine particles. In the test, in the same manner as in Production Example 1, when an array assembly of polystyrene beads was formed, the volume percentage of the polystyrene beads with respect to water was 0.03 vol%, 0.06 vol%, 0.12 vol%, 0.25 vol%, 0.5 The fine particle array structure was manufactured in place of volume% and 1 volume%, and the particles deposited on the side wall were observed with an electron microscope and the number thereof was measured. The result is shown in FIG.

  As is clear from FIG. 10, when the volume% of the fine particles in the fine particle suspension is changed within the range of 0 to 1% by volume, the fine particle filling rate is A positive correlation was observed between the two. Therefore, it became clear that the filling rate per unit volume of the fine particles on the side wall inside the groove can be controlled by adjusting the volume ratio of the fine particles in the fine particle suspension to the solvent.

<Test Example 4> (Influence of humidity in the outside atmosphere)
The influence of the humidity of the outside atmosphere on the filling rate per unit volume of the fine particles was examined. In the test, in the same manner as in Production Example 1, when forming an array assembly of polystyrene beads, the humidity inside the temperature-controlled room was changed to 50, 67, and 90%, and a fine particle array structure was manufactured, and its side wall The particles deposited on were observed with a CCD microscope. The results are shown in FIGS.

  As shown in FIGS. 11a and 11b, when dried at a humidity of 50%, a single-layered array of fine particles was formed on the side wall, whereas only fine particles were present on the bottom surface. As a result, an array aggregate of fine particles was not formed. 11c and 11d are diagrams schematically showing the obtained micrographs.

  As shown in FIGS. 12a and 12b, when the film was dried at a humidity of 67%, a single-layer array of fine particles was formed on the side wall. Moreover, the part which microparticles | fine-particles existed sparsely and the part which those aggregated were mixed on the bottom face. 12c and 12d are diagrams schematically showing the obtained micrographs.

  As shown in FIGS. 13a and 13b, when the film was dried at a humidity of 90%, an array of fine particle arrays was formed on the side wall. Also, an array of fine particles was formed on the bottom surface. FIGS. 13c and 13d are diagrams schematically showing the obtained micrographs.

  From the above, it became clear that the filling rate per unit volume of the fine particles on the bottom surface inside the groove can be controlled by adjusting the humidity of the outside air atmosphere.

<Test Example 5> (Consideration of influence of wettability to solvent on groove wall)
FIG. 14a shows a photograph showing a state when water is dropped on a silicon substrate treated with a fluorocarbon film. FIG. 14 b shows a photograph showing a state when water is dropped onto a silicon substrate treated with a sulfuric acid / hydrogen peroxide mixture solution (SPM). As shown in FIG. 14a, the wettability of water on the surface of the silicon substrate treated with the fluorocarbon film is lower than when water is dropped on the treated silicon substrate (FIG. 14b), and the contact angle between water and the substrate is 110. It was about degrees. Therefore, if such a treatment for reducing wettability is performed on a selected predetermined region of the wall portion of the groove, the above-mentioned meniscus tip portion does not occur, so that the formation of an array aggregate of partial particles does not occur. I thought it was not.

DESCRIPTION OF SYMBOLS 1 Substrate groove wall 2 Fine particle suspension 2a Fine particle 3 Solvent flow 4 Particle alignment portion thickness 5 Meniscus tip length 6 Retraction (movement) of meniscus tip
7 Drying of liquid 10 Silicon substrate 11 Protective mask 12 Resist opening 13 Groove 14 Protective film 15 Scalloped shape 20 Container 21 Temperature-controlled room 22 Lifting 30 Polystyrene bead single layer array aggregate 31 Polystyrene bead multi-layer array aggregate 32 Array assembly 50 Contact angle 51 Solvent 66 Retraction (movement) of the solvent at the substrate / solvent / outside air interface

Claims (9)

Filling the groove of the substrate having a groove having a predetermined width and depth on the surface with a fine particle suspension obtained by suspending fine particles in a solvent, and drying the solvent of the filled fine particle suspension. A method for producing a fine particle array structure in which the fine particles are arranged in a single layer or a plurality of layers on the wall portion of the groove to form an array aggregate of the fine particles, By using the fine particle suspension in which the volume ratio of the fine particles to the solvent is a predetermined value, the meniscus tip portion of the solvent in which the fine particles are suspended with respect to the groove wall portion is selected as the groove wall portion. A method for producing a fine particle array structure, wherein the fine particle array structure is formed only on a predetermined wall portion of the groove so as to move only in a predetermined region. Filling the groove of the substrate having a groove having a predetermined width and depth on the surface with a fine particle suspension obtained by suspending fine particles in a solvent, and drying the solvent of the filled fine particle suspension. A method for producing a fine particle arrangement structure in which the fine particles are arranged in a single layer or a plurality of layers on the wall of the groove, and the fine particle suspension is formed in the groove. Then, the solvent of the filled fine particle suspension is dried at a predetermined temperature, humidity, and / or atmospheric pressure, so that the meniscus tip portion of the solvent in which the fine particles are suspended with respect to the wall portion of the groove is formed. The fine particle array is characterized in that the fine particle array is formed only on the selected predetermined wall portion of the groove so as to move only in the selected predetermined region of the groove wall portion. Manufacturing method of structure. Filling the groove of the substrate having a groove having a predetermined width and depth on the surface with a fine particle suspension obtained by suspending fine particles in a solvent, and drying the solvent of the filled fine particle suspension. By the above, a method for manufacturing a fine particle array structure in which the fine particles are arranged in a single layer or a plurality of layers on the wall of the groove to form an array aggregate of the fine particles . The meniscus tip of the wall portion other than the wall portion with respect to the groove wall portion of the solvent in which the fine particles are suspended by making the wettability to the solvent of the fine particle suspension smaller than that of the selected wall portion. parts is so as to move only the selected predetermined regions of the wall of the groove, only a predetermined wall portion which is selected in the groove, characterized in that to form an array assembly of the fine particles Manufacturing method of fine particle arrangement structure. By immersing the substrate so that at least a part of the groove is in contact with the fine particle suspension, the fine particle suspension is filled into the groove by capillary action, and then the substrate is lifted to dry the substrate. The method for producing a fine particle array structure according to any one of claims 1 to 3 . The method for producing a fine particle array structure according to any one of claims 1 to 4 , wherein the substrate is selected from silicon, glass, alumina, ITO, plastic, or polycarbonate. The method for producing a fine particle array structure according to any one of claims 1 to 5 , wherein the groove has a width of 0.1 to 100 µm and a depth of 5 to 600 µm. The method for producing a fine particle array structure according to any one of claims 1 to 6 , wherein the fine particles have a particle diameter of 1 nm to 5 µm. The material of the fine particles is gold (Au), silver (Ag), copper (Cu), platinum (Pt), aluminum (Al), palladium (Pd), nickel (Ni), cobalt (Co) and other metals, oxidation Tin (SnO ₂ ), zinc oxide (ZnO), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), FeO ₃ , CdO, SrTiO ₃ , CoO, Fe ₃ O ₄ , Cu ₂ O, MgO, MnO, Ag _{2 O, in 2 O 3,} WO metal oxides such as _3, or polystyrene, microparticle production method array structure to any one of claims 1 to 7, an organic polymer such as an acrylic resin. Suspension of the fine particles filled in the groove under the conditions set based on the following formula (1) so that the filling rate (ε) of the fine particles with respect to the selected predetermined wall portion of the groove becomes a desired value. The method for producing a fine particle array structure according to any one of claims 1 to 8 , wherein the solvent of the liquid is dried.

(In the above formula, V is the meniscus retraction rate [m / s], h is the particle alignment portion thickness [m], Je is the drying rate [g / m · s], l is the meniscus length [m], and φ is (The volume fraction [%] of the fine particles in the solution, β is a proportional constant, and ε is the filling rate [%].)