Method for arranging fine particles on substrate by physical pressure

Abstract

Provided is a method of arranging particles on a substrate, the method including: (a) preparing a substrate, a surface of which has depressions or projections capable of fixing the positions and/or orientations of one or more particles; and (b) placing the particles on the substrate and applying a physical pressure to the particles so that a portion or the whole of each particle is inserted in each of pores defined by the depressions or the projections. Provided is also a method of arranging particles on a substrate, the method including: (a) preparing a substrate, at least a surface portion of which has adhesive property; and (b) placing particles, which do not have flat facets but curved surfaces, on the substrate and applying a physical pressure to the particles so that the particles are immobilized on adhesive surface portions of the substrate.

Claims

1. A method of arranging colloidal particles on a substrate, the method comprising: (a) preparing a substrate, a surface of which has depressions or projections defining pores capable of fixing the positions and/or orientations of one or more colloidal particles; (b) randomly placing on the substrate, a first plurality of dry colloidal particles in the absence of any solvent; and physically pressing the particles to provide immobilized particles and residual particles, wherein a portion or the whole of each of the immobilized particle is inserted in each of the pores, and the residual particles remain not immobilized on the substrate; and (c) removing the residual particles using an adhesive member, wherein the colloidal particles have sizes in a range of 10 nm-10 m.

2. The method of claim 1, wherein the depressions or the projections are formed by direct printing by lithography, printing using photoresist, laser ablation after sacrificial layer coating, or inkjet printing.

3. The method of claim 1, wherein the pores have shapes corresponding to the shapes of predetermined portions of the particles to be inserted in the pores so that the particles are oriented in predetermined directions.

4. The method of claim 1, wherein the shapes of the depressions and the projections are nanowells, nanodots, nanopillars, nanotrenches or nanocones.

5. The method of claim 1, wherein the pores receiving the particles have two or more different sizes and/or shapes.

6. The method of claim 1, wherein each of the depressions of the substrate comprises two or more another depressions capable of individually fixing the positions and/or orientations of the particles therein.

7. The method of claim 1, wherein the pores of the substrate form a predetermined pattern or shape, and the immobilized particles inserted into the pores form a pattern corresponding to the predetermined pattern or shape.

8. The method of claim 1, wherein a particle inserted in a pore and another particle inserted in an adjacent pore are contacted with or separated from each other by adjusting a distance between the pores.

9. The method of claim 1, further comprising: (d) placing a second plurality of colloidal particles on a monolayer formed by the first plurality of colloidal particles after step (c) and physically pressing the particles so that the particles are inserted into interstitial spaces defined by adjacent three or more of the particles constituting the monolayer.

10. The method of claim 9, wherein step (d) is performed once or more to form a two or more-layered array.

11. The method of claim 1, further comprising: (e) coating or filling with a transparent or opaque protecting material, after step (c).

12. The method of claim 1, wherein some particles are different in size or shape from some other particles, and whereby the first plurality of the particles are separated corresponding to the size or shape of the pores.

13. The method of claim 1, further comprising modifying exposed portions of the particles present in the pores.

14. A method of arranging colloidal particles on a substrate, the method comprising: (a) preparing a substrate having one or more adhesive surface portions; (b) randomly placing on the substrate, a plurality of dry colloidal particles in the absence of any solvent, wherein said dry colloidal particles do not have flat facets but curved surfaces, and physically pressing the particles so that the particles are immobilized on adhesive surface portions of the substrate; and (c) removing residual particles randomly placed on the particle array of step (b), which are not immobilized on the substrate, using an adhesive member, wherein the colloidal particles have sizes in a range of 10 nm-10 m.

15. The method of claim 14, wherein the adhesive surface portions of the substrate form a predetermined pattern or shape so that the particles immobilized on the adhesive surface portions of the substrate form a pattern or shape corresponding to the predetermined pattern or shape of the adhesive surface portions.

16. The method of claim 14, wherein the particles and/or the substrate are surface-coated with an adhesive material.

17. The method of claim 16, further comprising: removing the adhesive material coated on the particles and/or the substrate, after step (c).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flow diagram illustrating an embodiment of the first method of the present invention.

(2) FIG. 2(a) is a flow diagram illustrating an embodiment of the second method of the present invention.

(3) FIG. 2(b) is a diagram illustrating a substrate 100 with adhesive surface portions patterned or shaped with an adhesive material A.

(4) FIG. 3 is a diagram illustrating the insertion and arrangement of particles 200 in a predetermined orientation in patterned depressions 101 of a substrate 100. Here, arrows represent modification such as chemical treatment.

(5) FIG. 4(a) is a diagram illustrating first depressions 101 and second depressions 102 patterned on a substrate, and FIG. 4(b) is a diagram illustrating the arrangement of particles 200 in first and second depressions 101 and 102 patterned on a substrate 100.

(6) FIG. 5 is scanning electron microscopic (SEM) images showing undesired silica beads randomly attached onto 1D or 2D arrays of silica beads formed on PEI-coated glass plates by rubbing (panel (a): a 2D monolayer array of 1 m sized silica beads (1K magnification); panel (b): a 2D monolayer array of 20 nm sized silica beads (20K magnification); panel (c): a fcc (100) array of 300 nm sized silica beads (8K magnification); panel (d): a fcc (100) array of 700 nm sized silica beads (8K magnification); panel (e): a 1D wire parallel array of 700 nm sized silica beads (6K magnification); and panel (f): a 1D stripe parallel array of 700 nm sized silica beads (6K magnification).

(7) FIG. 6 is SEM images showing monolayer arrays of silica beads formed on flat glass plates by rubbing (panel (a): 1 m sized silica beads under 0.8K magnification; panel (b): 1 m sized silica beads under 7K magnification; panel (c): 200 nm sized silica beads under 5K magnification; panel (d): 200 nm sized silica beads under 35K magnification; panel (e): 20 nm sized silica beads under 10K magnification; panel (f): 20 nm sized silica beads under 40K magnification).

(8) FIG. 7 is images showing the efficiency of the inventive methods on large-scale substrates (1515 cm.sup.2) (panel (a): a digital camera image of a bare glass plate; panel (b): a digital camera image of a glass plate wholly coated with 2D monolayer array of 1 m sized silica beads; panel (c): a SEM image of the panel (b) under 2.5K magnification; and panel (d): a SEM image of the panel (b) under 15K magnification).

(9) FIG. 8 is SEM images showing 2D monolayer arrays of silica beads on flat glass plates (panel (a): 700 nm sized silica beads under 2.5K magnification; panel (b): 700 nm sized silica beads under 10K magnification; panel (c): 500 nm sized silica beads under 2K magnification; panel (d): 500 nm sized silica beads under 7K magnification; panel (e): 20 nm sized silica beads under 10K magnification; and panel (f): 20 nm sized silica beads under 30K magnification). For the arrays of 700 nm and 500 nm sized silica beads, a 0.125% PEI solution was spin-coated on the glass plates. For the arrays of 20 nm sized silica beads, a 0.0625% PEI solution was spin-coated on the glass plates.

(10) FIG. 9(a), (b), and (c) are SEM images showing silicone wafers patterned with nano-sized 2D arrays (panel (a): a tetragonal well array with 500 nm in diameter, 250 nm in depth and 700 nm in pitch; panel (b): a hexagonal well array with 250 nm in depth and 200 nm in top diameter; panel (c): a 2D array of truncated cones with 250 nm in bottom diameter). The arrays of the panels (a), (b) and (c) were respectively used as templates for 2D fcc (100) (panel (d)), fcc (111) (panel (e)) and fcc (100) (panel (f)) arrays of 700 nm sized silica beads. The panel (g) is a 2D fcc (100) array of 700 nm sized silica beads and the panel (h) is a 2D fcc (111) array of 700 nm sized silica beads [panels (a) to (f); 20K magnification, panels (g) to (j); 8K magnification].

(11) FIG. 10 is SEM images showing 2D fcc (100) monolayer arrays of 700 nm sized silica beads on patterned silicone wafers (1 cm1 cm) (panel (a): 1K magnification; panel (b): 3K magnification; panel (c): 5K magnification; and panel (d): 10K magnification). A 0.25% PEI solution was spin-coated on the silicone wafers.

(12) FIG. 11 is SEM images showing 2D fcc (111) arrays of 700 nm sized silica beads on patterned silicone wafers (1 cm1 cm) (panel (a): 1K magnification; panel (b): 5K magnification; panel (c): 10K magnification; panel (d): 15K magnification). A 0.25% PEI solution was spin-coated on the silicone wafers.

(13) FIG. 12 is SEM images showing 2D fcc (100) arrays of 500 nm sized silica beads on patterned silicone wafers (1 cm1 cm) (panel (a): 1K magnification; panel (b): 5K magnification; panel (c): 10K magnification; panel (d): 15K magnification). A 0.25% PEI solution was spin-coated on the silicone wafers.

(14) FIG. 13 is SEM images showing 2D fcc (111) arrays of 500 nm sized silica beads on patterned silicone wafers (1 cm1 cm) (panel (a): 0.6K magnification; panel (b): 2K magnification; panel (c): 4K magnification; panel (d): 9K magnification). A 0.25% PEI solution was spin-coated on the silicone wafers.

(15) In the panels (a) and (b) of FIGS. 11 to 13, black spots (represented by circles) were caused by the presence of smaller sized silica beads on corresponding spots.

(16) FIG. 14 is SEM images showing 2D fcc (100) arrays of 300 nm sized silica beads on patterned silicone wafers (1 cm1 cm) (panel (a): 6K magnification; panel (b): 10K magnification; panel (c): 15K magnification).

(17) FIG. 15 is SEM images showing 2D fcc (111) arrays of 300 nm sized silica beads on patterned silicone wafers (1 cm1 cm) (panel (a): 6K magnification; panel (b): 10K magnification; panel (c): 15K magnification).

(18) FIGS. 16(a) and (b) are SEM images showing silicone wafers coated with PR films of 350 nm in thickness that were patterned with wells of 500 nm in diameter and 700 nm in pitch to form a tetragonal net array (panel (a)) and a hexagonal net array (panel (b)). Panels (c) and (d) are SEM images showing 2D arrays of 700 nm sized silica beads on the silicone wafers of the panels (a) and (b), respectively. Panels (e) and (f) are SEM images showing free-standing, 2D fcc (100) and fcc (111) monolayer arrays, respectively, of 700 nm sized silica beads on flat silicone wafers after PR removal.

(19) FIG. 17 is SEM images showing 1D, 2D and 3D close-packed arrays of 700 nm sized silica beads on patterned silicone wafers (panel (a): 1D wires; panel (b): 1D fcc (100) stripes; panel (c): 1D fcc (111) stripes; panel (d): a mixed 1D pattern of fcc (100) stripes and fcc (111) stripes; panel (e): a mixed 2D pattern of fcc (100) and fcc (111) arrays; panel (f): a 3D fcc (100) array formed by a layer-by-layer pattern (five layers).

(20) FIG. 18 is SEM images showing diversely patterned arrays of silica beads on silicone wafers.

(21) FIG. 19 is SEM images showing binary 2D arrays of 700 nm and 300 nm sized silica beads (panel (a)) and 700 nm and 420 nm sized silica beads (panel (b)); a non-close packed 2D array of 420 nm sized silica beads (panel (c)); a non-close packed 2D array formed by inserting two 300-nm sized silica beads in each pore (panel (d)), a non-close packed 2D array formed by inserting three 250-nm sized silica beads in each pore (panel (e)); and a non-close packed 2D array formed by inserting four 230-nm sized silica beads in each pore (panel (f)). Here, silicone wafers patterned with tetragonal net arrays of nanowells (500 nm in diameter, 250 nm in depth, 700 nm in pitch) were used.

(22) FIG. 20 is a SEM image (3K magnification) showing a non-close packed 2D array of 500 nm sized silica beads on a patterned silicone wafer (1 cm1 cm).

(23) FIGS. 21 and 22 are SEM images showing the insertion of four (FIG. 21) or seven (FIG. 22) silica beads in each depression having a shape corresponding to an outer shape defined by the four or seven silica beads.

(24) FIGS. 23(a), (b) and (c) are diagrams illustrating a process of inserting larger spherical PMMA polymer particles (to be removed later) in spaces defined by first and second monolayers of silica beads to achieve a snowman-like layered array of the silica beads.

(25) FIG. 24 is a diagram illustrating a snowman-like layered array of the silica beads left after removing the PMMA polymer particles from the diagram of FIG. 23.

(26) FIG. 25 is SEM images showing silicone wafers negatively patterned with PR in order to receive crystalline silica particles with a-, b- and c-axes in corresponding axis directions.

(27) FIG. 26 is SEM images showing anisotropic, coffin shape silicalite-1 crystals and anisotropic leaf shape silicalite-1 crystals; and crystal axes thereof.

(28) FIGS. 27 through 30 are SEM images showing a-, b- and c-axis assemblies of crystalline silica particles with a-, b- and c-axes inserted in silicone wafers negatively patterned with PR as shown in FIG. 25.

(29) FIG. 31 is SEM images showing the assemblies of crystalline silica particles with a-, b- and c-axes inserted in silicone wafers negatively patterned with PR, left after PR removal by calcination.

DETAILED DESCRIPTION OF THE INVENTION

(30) Hereinafter, the present invention will be described with reference to the following examples but is not limited thereto.

Examples

(31) Experimental Methods

(32) Throughout the specification, a percentage (%) used to represent the concentration of a material is wt/wt % unless stated otherwise.

(33) <Preparation of Silica Beads>

(34) A solution of tetraethylorthosilicate (TEOS, 20 ml, Aldrich) in ethanol (350 ml) was hydrolyzed in the presence of NH.sub.4OH (35%, 75 ml) at room temperature to prepare 20 to 1000-nm sized silica beads according to the Stober method (Stober, W. et al., Journal Interface Science 26:62-69 (1968)). The sizes of the silica particles were adjusted by changing the concentrations of TEOS and NH.sub.4OH. For example, for the preparation of 500 nm sized silica beads, 20 ml TEOS was added to a solution containing 350 ml ethanol and 75 ml 35% NH.sub.4OH, and the resultant solution was stirred at room temperature for three hours. In order to increase the size of silica beads from 500 nm to 700 nm, 16 ml TEOS and 8 ml NH.sub.4OH were simultaneously dropwise added to a solution containing 500 nm sized silica beads. For the preparation of smaller sized silica beads, TEOS and NH.sub.4OH were used in smaller amounts.

(35) The silica beads thus produced were washed with ethanol (3) and then with water (3).

(36) The washed silica beads were lyophilized. The standard size deviation of the resultant silica beads was 2%.

(37) <Preparation of Substrates Surface-Coated with an Adhesive>

(38) Glass plates (2.5 cm2.5 cm, Marienfield) were placed in a piranha solution (a ratio of H.sub.2SO.sub.4 to H.sub.2O.sub.2=7:3) for 30 minutes and washed with deionized water. The washed glass plates were incubated in ethanol and then dried under highly pure nitrogen atmosphere. The dried glass plates were spin-coated with polyethyleneimine (PEI, Mw=25000, Aldrich). The spin coating was started at a spinning speed of 600 rpm, with gradual increase to 1000 rpm for one minute.

(39) For monolayer assembly of silica beads, the concentration of PEI was 0.0625% for 20-nm sized silica beads, 0.125% for 200300 nm sized silica beads, and 0.5% for 7001000 nm sized silica beads.

(40) <Preparation of Directly Patterned Substrates>

(41) Tetragonal or hexagonal net arrays of nanowells or nanocones were formed on silicone wafers using lithography (NNFC (National NanoFab Center), Korea). The sizes of the silicone wafers used were 1 cm1 cm. The diameters of the nanowells were 500 nm for 700 nm sized silica particles, 300 nm for 500 nm sized silica particles, and 200 nm for 300 nm sized silica particles. The depths of the nanowells were 250 nm. A well-to-well distance (pitch) was designed to be the same as the size of each of silica particles to be arrayed. For example, in case of forming an array of 700 nm sized silica particle, a well-to-well distance is 700 nm. The nanocones were sized to have a bottom diameter of 250 nm, a top diameter of 200 nm and a height of 200 nm. The distance between adjacent ones of the nanocones was designed to be 700 nm for arrays of 700 nm sized silica particles.

(42) <Preparation of Substrates Patterned with PR>

(43) Silicone wafers (p-type) coated with patterned PR (tetragonal or hexagonal net arrays of nanowells) were prepared (NNFC, Korea). The wafers were sized to have an area of 1 cm1 cm. The diameters of the nanowells formed in the PR were 500 nm, 300 nm and 200 nm for 700 nm, 500 nm and 300 nm sized silica beads, respectively. The depths of the nanowells were 250 nm regardless of the diameters of the nanowells.

(44) <Arrangement of Particles Using Rubbing>

(45) In case of using the patterned silicone wafers and glass plates, a small amount (2 mg) of powdered silica beads were placed on PEI-coated substrates (glass plates or patterned silicone wafers), and the silica beads were repeatedly gently rubbed in predetermined directions using PDMS (poly(dimethysiloxane)) plates (4.04.00.5 cm.sup.3). The rubbing was performed for about one minute until a substrate surface got slight rainbow colors by light reflection.

(46) In case of using the patterned PR-coated silicones wafers, the powdered silica beads were placed on the patterned PR-coated wafers, and then repeatedly gently rubbed in a predetermined direction using a PDMS plate in the presence of water. Here, water was used as a lubricant to prevent damage to the patterned PR.

(47) <Formation of Monolayer Arrays>

(48) After the rubbing, the silica bead-coated glass plates or silicone wafers were subjected to slight pressing using clean PDMS plates or to gentle brushing in order to remove randomly physically adsorbed, undesired silica beads, thus resulting in formation of more tightly, regularly bound monolayer arrays of the silica beads.

(49) <Formation of Multilayer Arrays 1>

(50) For layer-by-layer stacking, the above-formed monolayer arrays were calcined at 550 C. for one hour. A droplet of a solution of PEI (0.5%) in ethanol was spin-coated on the calcined silica bead arrays. Silica beads were further placed on the PEI-coated silica bead arrays, and then were rubbed as described above to form two-layered silica bead arrays. Through the repetition of the above-described procedure, it was possible to form 3D arrays of silica beads with a desired number of layers (i.e., a desired thickness).

(51) <Formation of Multilayer Arrays 2>

(52) The above-formed monolayer arrays were calcined at 550 C. for one hour. A droplet of a solution of PEI (0.5%) in ethanol was spin-coated on the calcined silica beads (200 nm). PMMA polymer balls (700 nm) were stacked on the PEI-coated silica bead monolayers using rubbing. Then, PEI coating was applied thereto and silica beads were further stacked thereon by rubbing (FIG. 23). Then, the PMMA polymer balls were removed by calcinations to thereby form a snowman-like layered array of silica beads (FIG. 24). Through the repetition of the above-described procedure, it was possible to form 3D arrays of silica beads with a desired number of layers (i.e., a desired thickness).

(53) Experimental Results

(54) Silica beads (20 nm to 1 m in diameter) were prepared. Glass plates (2.52.5, 1515 cm.sup.2 in area) and patterned silicone wafers (1.01.0 cm.sup.2 in area) were used as substrates. For the patterned silicone wafers, silicone wafers were patterned with tetragonal or hexagonal net arrays of 250-nm depth nanowells of 200 nm and 300 nm in diameter and pitch, of 350 nm and 500 nm in diameter and pitch, and of 500 nm and 700 nm in diameter and pitch. Also, there were prepared silicone wafers coated with 350-nm thick PR patterned with tetragonal or hexagonal net arrays of wells of 200 nm and 300 nm in diameter and pitch, of 350 nm and 500 nm in diameter and pitch, and of 500 nm and 700 nm in diameter and pitch. Also, there were prepared silicone wafers patterned with tetragonal arrays of truncated cone pillars (200 nm in top diameter, 250 nm in bottom diameter, 700 nm in pitch, and 250 nm in height), and silicone wafers patterned with tetragonal net arrays of cylindrical PR pillars (300 nm, 700 nm in pitch, 350 nm in height, 200 nm in diameter). Hereinafter, the substrates will be described as symmetry-pattern shape-(pattern dimensions, i.e., a diameter of a well/cylinder or a bottom diameter of a cone/a pitch)-material. Here, the symmetry is T (tetragonal) or H (hexagonal), the pattern shape is Wel (wells), Cyl (cylinders), or Con (cones), and the material is Si (silicone) or PR/Si (PR-coated silicone). The number of the patterns for each substrate were as follows: T-Wel-(500/700)-Si: 14,28614,286 (2.010.sup.8); H-Wel-(500/700)-Si: 14,28616,496 (2.410.sup.8); T-Wel-(350/500)-Si: 20,00020,000 (4.010.sup.8); H-Wel-(350/500)-Si: 20,00023,094 (4.610.sup.8); T-Wel-(200/300)-Si: 33,33333,333 (11.110.sup.8); H-Wel-(200/200)-Si: 33,33338,490 (12.810.sup.8).

(55) A small amount (2 mg) of dried 1 m sized silica beads were placed on PEI-coated glass plates (2.52.5 cm.sup.2), and the silica beads were repeatedly gently rubbed in one direction using a PDMS plate (4.04.00.3 cm.sup.3) for about 30 seconds until surfaces of the glass plates got slight rainbow colors by light reflection. As shown in SEM images of FIG. 5, it was observed that some silica beads were undesirably randomly arranged on 2D monolayer arrays. When PDMS plates were placed and gently pressed on the randomly arranged silica beads, the randomly arranged silica beads were easily removed, thus resulting in high-quality 2D monolayer arrays of silica beads on the whole surfaces of the glass plates (FIG. 6, panels (a) and (b)). Therefore, unlike conventional self assembly in solvents, there were no needs to dry the resultant monolayers, thus eliminating crack formation due to particle shrinkage during drying.

(56) For very large (1515 cm.sup.2) substrates, the same effects as described above were achieved (FIG. 7). The use of smaller silica beads, i.e., 700-nm sized silica beads (FIG. 8), 500-nm sized silica beads (FIG. 8), 200-nm sized silica beads (FIG. 6, panels (c) and (d)), 60-nm sized silica beads (FIG. 8) and 20-nm sized silica beads (FIG. 6, panels (e) and (f)) also enabled to achieve excellent effects as described above. These results suggest that the inventive methods are very effective regardless of particle sizes.

(57) According to the same method as described above, monolayer arrays of 700-nm sized silica beads on patterned substrates, i.e., T-Wel-(500/700)-Si, H-Wel-(500/700)-Si, and T-Con-(250/700)-Si (FIG. 9, panels (a) to (c)) were manufactured. As a result, silica beads were accurately individually inserted in wells (FIG. 9, panels (d), (e)) or in spaces defined by adjacent four ones of truncated cones (FIG. 9, panel (f)), thereby resulting in perfect, fcc (100) and fcc (111) arrays of the silica beads. According to SEM analysis, silica beads formed prefect 2D monolayer arrays on the whole surfaces of the substrates (FIG. 9, panels (g), (h); FIGS. 10 to 15).

(58) Similarly, for silica bead arrays on T-Wel-(300/500)-Si, H-Wel-(300/500)-Si, T-Wel-(200/300)-Si, and H-Wel-(200/300)-Si substrates (1.01.0 cm.sup.2), perfect 2D fcc (100) and fcc (111) monolayer arrays of 500 nm (FIGS. 12, 13) and 300 nm (FIG. 9, panels (i), (j); FIGS. 14, 15) sized silica beads on the entire surfaces of the substrates were achieved. These results suggest that it is possible to form 2D silica bead monolayer arrays with symmetry and orientations based on a centimeter scale (up to 10-inch size) within one minute. Furthermore, thus-formed particle monolayers can have crystal-like arrays, and thus, assemblies of particles oriented in predetermined crystal axes can have optical characteristics, thereby enabling the application of them in the field of optical technology.

(59) For patterned PR-coated silicone wafers, i.e., T-Wel-(500/700)-PR/Si (FIG. 16, panel (a)) and H-Wel-(500/700)-PR/Si (FIG. 16, panel (b)), high-quality, large-scale 2D monolayer arrays were also obtained (FIG. 16, panels (c), (d)). In this case, rubbing was more softly performed since the mechanical strength of PR is lower than that of silicone.

(60) For PR-coated substrates, PR layers can be easily removed by methanol, and thus, it is possible to form free-standing 2D silica monolayers supported on flat substrates (FIG. 16, panels (e), (f)). This method can be used in formation of large-scale 2D monolayers of particles on various substrates.

(61) Much attention has been paid to pattern-induced arrays of colloidal particles on a fcc (100) surface (A. van Blaaderen, R. Ruel, P. Wiltzius, Nature 1997, 385, 321; J. P. Hoogenboom, C. Re'tif, E. de Bres, M. van de Boer, A. K. van Langen-Suurling, J. Romijn, A. van Blaaderen, Nano Lett. 2004, 4, 205; Y. Yin, Y. Lu, B. Gates, Y. Xia, J. Am. Chem. Soc. 2001, 123, 8718). However, only substrates patterned with tetragonal net arrays of pillars (not wells) were effective (A. van Blaaderen, R. Ruel, P. Wiltzius, Nature 1997, 385, 321). In this case, 500500 sites (2.510.sup.5 sites) were imperfectly filled with silica beads, even when using substrates having areas 0.1% smaller than the areas of substrates used in the present invention. Moreover, it was impossible to form large-scale (1 cm.sup.2) fcc (111) monolayer arrays even when using a patterned substrate.

(62) According to the inventive methods, it was also possible to achieve 1D arrays, i.e., wire arrays (FIG. 17, panel (a)), fcc (100) stripe arrays (FIG. 17, panel (b)), fcc (111) stripe arrays (FIG. 17, panel (c)), and combination arrays thereof (FIG. 17, panel (d)).

(63) It was also possible to achieve simultaneous 2D arrays into fcc (100) and fcc (111) lattice structures (FIG. 17, panel (e)).

(64) Formation of different two types of symmetric arrays on only one substrate has not yet been achieved. Formation of 1D wires/stripes through self-assembly in solvents is known in the art (A. van Blaaderen, R. Ruel, P. Wiltzius, Nature 1997, 385, 321; J. P. Hoogenboom, C. Re'tif, E. de Bres, M. van de Boer, A. K. van Langen-Suurling, J. Romijn, A. van Blaaderen, Nano Lett. 2004, 4, 205; Y. Yin, Y. Lu, B. Gates, Y. Xia, J. Am. Chem. Soc. 2001, 123, 8718). However, lateral ordering of silica beads in 1D arrays has not yet been reported.

(65) When repeatedly forming the fcc (100) arrays of the same-sized silica beads on substrates (1 cm.sup.2) according to the inventive methods, it is possible to achieve perfect 3D fcc arrays grown in the [100] direction. This result is seen by panel (f) of FIG. 17 (use of 700 nm sized silica beads).

(66) After calcining a first layer of a close-packed array of 700 nm sized silica beads on a T-Wel-(500/700)-Si substrate, PEI coating, application of silica beads with a different size from the silica beads constituting the first layer, and rubbing enabled to easily produce a binary 2D, tetragonal net array of different sized silica beads. For example, when calcining the 2D monolayer arrays of 700 nm sized silica beads on T-Wel-(500/700)-Si substrates, and placing and rubbing 300 nm or 420 nm sized silica beads on the monolayers, 2D binary, tetragonal net arrays of 700 nm/300 nm (FIG. 19, panel (a)) and 700 nm/420 nm (FIG. 19, panel (b)) sized silica beads were obtained.

(67) According to the present invention, it is possible to achieve 2D non-close packed arrays of 700 nm or less sized silica beads on T-Wel-(500/700)-Si substrates. This was demonstrated using 500 nm (FIG. 20) and 420 nm (FIG. 19, panel (c)) sized silica beads.

(68) The insertion of silica beads in patterned wells with diameters that are the same as or greater than the sizes of the silica beads can be easily rapidly performed relative to the organization of silica beads into fcc (100) or fcc (111) arrays. Interestingly, when using 420 nm sized silica beads and 500 nm diameter wells, the silica beads could be located in internal sides of the wells through rubbing in one direction (FIG. 19, panel (c)). When using silica beads with smaller sizes, i.e., 300 nm, 250 nm and 230 nm, two (FIG. 19, panel (d)), three (FIG. 19, panel (e)) and four (FIG. 19, panel (f)) silica beads were inserted in each of 500 nm diameter wells. This shows that the inventive methods can more easily and rapidly achieve the array of colloidal particles as compared with the Xia et al. method employing self-assembly in solvents (Y. Yin, Y. Lu, B. Gates, Y. Xia, J. Am. Chem. Soc. 2001, 123, 8718).

(69) It is interesting that, during rubbing according to the present invention, the application of strong force to silica bead particles induces deformation of wells and silica beads. For example, 500 nm diameter circular wells were deformed to an oval shape so that two 300 nm sized silica beads were received in each well. At this time, silica beads were also deformed to an oval shape. The panel (f) of FIG. 19 shows that the wall thickness of 500 nm diameter wells was thinner so that four 230 nm-sized silica beads were received in each well. These results suggest that wells can receive silica beads sized about 10% larger than a well diameter by natural deformation, and thus, the inventive methods are more flexible than conventional self-assembly in terms of the sizes and shapes of particles.

(70) The above-described experimental results demonstrate the excellent effects of the present invention, i.e., simple, rapid, and precise arrays on a large-scale area.

(71) While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

DESCRIPTION OF REFERENCE NUMERALS

(72) TABLE-US-00001 100: substrate, 101: first depression 102: second depression, 200: particle, A: adhesive material