WO2008147044A1

WO2008147044A1 - Nano structure of block copolymer and method for preparing the same

Info

Publication number: WO2008147044A1
Application number: PCT/KR2008/002244
Authority: WO
Inventors: Sang Ouk Kim; Seong Jun Jeong; Bong Hoon Kim; Dong Ok Shin
Original assignee: Korea Advanced Institute Of Science And Technology
Priority date: 2007-05-25
Filing date: 2008-04-21
Publication date: 2008-12-04
Also published as: KR20080103812A; KR100885666B1

Abstract

Disclosed herein are block copolymer nanostructures and a method for fabricating the same. More specifically, disclosed is a method for fabricating block copolymer nanostructures, which comprises forming a block copolymer film on an oxide substrate and heat-treating the formed block copolymer to form self- assembled nanostructures. According to the disclosed method, block copolymer nanostructures can be fabricated on various oxide substrates, and self-assembled nanostructures, which have various shapes depending on the relative composition ratios of blocks forming the block copolymer, can be fabricated.

Description

NANO STRUCTURE OFBLOCK COPOLYMERAND METHOD FOR PREPARINGTHE SAME

TECHNICAL FIELD

The present invention relates to block copolymer nanostructures and a method for fabricating the same, and more particularly to a method for fabricating block copolymer nanostructures, which comprises forming a block copolymer film on an oxide substrate, and then heat-treating the block copolymer to form self-assembled nanostructures.

BACKGROUND ART

A diblock copolymer, which is the simplest case of block copolymer, consists of two different homopolymers chemically attached together at their ends. Herein, the linked homopolymers undergo phase separation due to their different properties, and the resulting self-assembled block copolymer has a wide range of domain size (about 5-100 nm). Thus, it is possible to fabricate nanostructures with various shapes.

In order to maximize the range of practical application of nanostructures formed by block copolymers, it is important to form a thin film on a specific substrate, and then induce the formation of a stable nanostructure in the film. However, in the case of the block copolymer thin film, there are problems frequently occurring such as forming nanostructures different from that in bulk phase, or assembling into undesired nanostructures or the like, due to the interaction between a self- assembling material and a substrate. Thus, technologies for controlling the orientation or arrangement of nanostructures in thin films are required.

In a method of controlling the orientation or arrangement of nanostructures using an electric field, nanostructures are oriented in a desired direction using the principle that nanostructures show anisotropy due to the differences in the dielectric constants of the block copolymer nanostructures upon the application of the electric field. Recently, a method of forming vertically oriented cylindrical nanostructures by applying the above method to block copolymer thin films was reported.

However, this method has a problem in that electrodes, to which an electric field can be applied, must be provided on both sides of the block copolymer film.

A graphoepitaxy technique uses top-down micropatterning to control block copolymer nanostructures. In general, nanostructure orientation is controlled by fabricating micron or submicron patterns on a substrate through patterning methods such as lithography and applying a block copolymer thin film on the pattern to induce coupling between block copolymer nanostructures and patterns. Herein, the coupling occurs when the size of the pattern used as a substrate is integer times the size of the block copolymer nanostructure. If the size of the substrate pattern is excessively large, the orientation of the nanostructure will be impaired, even though the pattern size is integer times the size of the nanostructure. This orientation technique is called "graphoepitaxy", and it has a problem in that the applications thereof are limited, because prominences and depressions must be formed on a substrate through patterning.

An epitaxial self-assembly method enables a perfectly controlled self-assembled nanostructure to be obtained by forming a chemical pattern, conforming to the shape of the block copolymer nanostructure, on an organic monomolecular layer, using a top-down lithographic patterning method to control the block copolymer nanostructure, and inducing the self-assembly of the pattern. This method can overcome the limitation of self-assembling material that shows a desired structure only in a limited area, which has been pointed out as a problem in most studies conducted to date. Thus, this method is considered as a study result showing the possibility that the nanostructure formed using the method can be used in practical device fabrication processes. In this method, it is most important to form a fine chemical pattern conforming to the block copolymer nanostructure. However, the applications thereof are limited, because the formation of the organic monomolecular layer for forming the chemical pattern is possible only on a very limited range of substrates, such as a silicon dioxide (SiO₂) or indium tin oxide (InSnO) film.

Meanwhile, Korean Patent Registration No. 532812 discloses a bioreceptor, formed using a block copolymer nanopattern formed through self-assembly of block copolymer, and a nano-biochip, in which bioreceptor binding to a target biomaterial is selectively attached to a nanopattern of a metal having affinity for the bioreceptor. However, in the above patent, a substrate, on which the block copolymer nanopattern can be formed, is limited to a substrate having a thin film of a metal, having affinity for the bioreceptor, formed thereon. In other words, the substrate is limited to a metal, such as gold (Au), silver (Ag), platinum (Pt), niobium (Nb), tantalum (Ta), zirconium (Zr) or an alloy of cobalt (Co) with chromium (Cr), which can form a thin film on a substrate. For this reason, the above patent does not satisfy the requirements for technologies, which enable various block copolymer nanopatterns to be formed on various substrates, such that they can be used in various applications.

Thus, in the art to which the present invention pertains, there is an urgent need to develop a technology, which overcomes the above-described problems and enables block copolymer nanostructures, having various shapes, to be formed on various substrates, such that the nanostructures can be used in various applications.

Accordingly, the present inventors have made many efforts to solve the above- described problems occurring in the prior art and, as a result, have found that nanostructures having various shapes can be fabricated by depositing various oxides on substrates, forming a block copolymer film on the substrates, and then heat-treating the block copolymer, thereby completing the present invention.

SUMMARY OF INVENTION

It is an object of the present invention to provide a method of fabricating block copolymer nanostructures using an oxide substrate and nanostructures having various shapes, fabricated using said method.

To achieve the above object, the present invention provides a method for fabricating a block copolymer nanostructure, comprising the steps of: (a) forming an oxide substrate; (b) forming a block copolymer film on the surface of the oxide substrate; and (c) heat-treating the block copolymer to form a self-assembled nanostructure.

In the present invention, the oxide in the step (a) is preferably a conductive oxide or a nonconductive oxide. The conductive oxide is preferably a binary conductive oxide or a ternary conductive oxide. The binary conductive oxide is preferably selected from the group consisting of RuO_x, PdO_x, IrO_x, PtO_x, OsO_x, RhO_x, ReO_x and ZnO_x, and the ternary conductive oxide is preferably selected from the group consisting of SrRuO₃, In_1-xSn_xO₃, Na_xW_1-xO₃, Zn_x(Al₅Mn) _1-XO and Lao.₅Sro.₅CoO> The non-conductive oxide is preferably a binary non-conductive oxide or a ternary non-conductive oxide. The binary nonconductive oxide is preferably selected from the group consisting of AlO_x, TiO_x, TaO_x, HfO_x, BsO_x, VO_x, MoO_x, SrO_x,

NbO_x, MgO_x, SiO_x, FeO_x, CrO_x, NiO_x, CuO_x and ZrO_x, and the ternary nonconductive oxide is preferably selected from the group consisting of SiTiO₃, BaTiO₃, Al_xTi_1-xO_y, HfSi_1-xO_y, HfAl_1-xO_y, TixSi_1-xO_y and LaTiO₃. In the present invention, the method preferably additionally comprises a step of forming a neutral layer on the oxide substrate. The neutral layer is preferably an organic monolayer film or a neutral layer formed using etching. Also, the neutral layer preferably functions to enable the self-assembled block copolymer nanostructure to grow vertically.

In the present invention, the organic monolayer is preferably selected from the group consisting of a self-assembled monolayer (SAM), a polymer brush and MAT. The self-assembled monolayer is preferably selected from the group consisting of phenethyltrichlorosilane (PETCS), phenyltrichlorosilane (PTCS), benzyltrichlorosilane (BZTCS), tolyltrichlorosilane (TTCS), 2- [(trimethoxysilyl)ethyl]-2-pyridine (PYRTMS), 4-biphenylyltrimethowysilane (BPTMS), octadecyltrichlorosilane (OTS), 1-naphthyltrimehtoxysilane (NAPTMS), l-[(trimethoxysilyl)methyl]naphthalene (MNATMS) and (9- methylanthracenyl)trimethoxysilane (MANTMS), and the polymer brush is preferably PS-random-PMMA. Also, the MAT is preferably BCB-functionalized polystyrene-r-poly(methacrylate) copolymer [P(s-r-BCB-r-MMA)].

In the present invention, the block copolymer preferably has a structure in which polystyrene and a polymer other than polystyrene are covalently bonded to each other. The block copolymer is preferably selected from the group consisting of PS-b-PMMA, PS-b-PEO, PS-b-PVP, PS-b-PEP and PS-b-PI.

In another aspect, the present invention provides block copolymer nanostructures having various shapes.

Other features and aspects of the present invention will be apparent from the following detailed description and the appended claims. BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows various block copolymer nanostructures formed according to the composition ratios of block copolymers.

FIG. 2 is a scanning electron micrograph showing the upper portion of a nanostructure formed on a platinum substrate according to Example 1 of the present invention.

FIG. 3 is a scanning electron micrograph showing the upper portion of a nanostructure formed on a titanium dioxide substrate according to Example 2 of the present invention.

FIG. 4 depicts optical micrographs (FIG. 4a) and AFM micrographs (FIG. 4b) of the upper portions of nanostructures formed on ruthenium (Ru), iridium (Ir), zinc aluminum oxide (Zn-Al-O) and niobium-doped strontium titanate (Nb-SrTiO₃).

DETAILED DESCRIPTION OF THE INVENTION, AND PREFERRED EMBODIMENTS

The present invention relates to a method for fabricating block copolymer nanostructures having various shapes, the method comprising depositing various oxide films, including conductive oxides and nonconductive oxides, on substrates, to form oxide substrates, forming a block copolymer film on the oxide substrates and inducing self-assembly of the block copolymer through heat treatment, and various block copolymer nanostructures having various shapes, fabricated according to said method.

In the present invention, the oxides function to form the block copolymer film thereon, and specific examples thereof may include conductive oxides and nonconductive oxides. Particularly, the conductive oxides function as electrodes, such that the orientation of nanostructures can be controlled using an electric field without providing separate electrodes.

In the present invention, when the conductive oxides or nonconductive oxides are used to form oxide substrates, it is preferable to use deposition processes, single- crystal formation processes, solid phase processes or sol-gel processes.

Herein, the deposition processes are classified into wet deposition processes and dry deposition processes. The wet deposition processes include electroplating in which the surface of an object is covered with a thin film of another metal using the principle of electrolysis, and electrophoresis in which the surface of an object is covered with a film by placing electrodes in a colloidal solution and applying direct- current voltage to the electrodes to cause the colloidal particles to move toward any one of the electrodes. The dry deposition processes include physical vapor deposition, chemical vapor deposition and atomic layer deposition. The physical vapor deposition means a sputtering process comprising allowing an inert element such as argon to collide against a metal plate to eject a metal molecule from the metal plate, and then applying the metal molecule to a surface, or an evaporation process comprising evaporating a material by heating in a vacuum, and then applying the evaporated material to the surface of another material to form a film on the surface. The chemical vapor deposition (CVD) means a process of forming thin films on the surfaces of substrates through chemical reactions between gaseous components. The atomic layer deposition (ALD) refers to a technique of depositing a film in an atomic layer unit by supplying at least two reactive gases in a pulse form alternately.

The single-crystal formation processes are processes of growing grains from crystal nuclei so as to form a regular arrangement of elements, and include an aqueous solution method, a Czochralski method, a slow cooling method, a Bridgman- Stockbarger method, a hydrothermal method, Nongra-vitizing method and the like. In the present invention, the single-crystal formation processes are preferably carried out using a single crystal selected from the group consisting Of Nb-SrTiO₃, (NH₂CH₂COOH)₃-H₂SO₄, CDP(CsH₂PO₄), LiKSO₄, NiSO₄, L- Arginine(C₆H₁₄N₄O₂), KDP(KH₂PO₄), ADP(NH₄H₂PO₄), Co(SO₄)₂-6H₂O, MnCl₂-2H₂O, Rochelle salt(KNaC₄H₄O₆-4H₂O), KHSO₄, CuSO₄- 5H₂O, LiNH₄SO₄, LiCsSO₄, K₂ZnCl₄-2H₂O, K₂ZnCl₄-2H₂O, CsMnCl₃-2H₂O and CsMnCl₃-2H₂O.

The solid phase processes are processes of preparing desired particles through the diffusion of solid particles and comprise thoroughly mixing solid oxide particles, heat-treating the particle mixture at high temperature, milling the heat-treated particles, and repeating the heat treatment and milling processes.

The sol-gel processes are processes for preparing "sol-gel derived ceramics". As used herein, the term "sol" refers to a colloidal suspension in which particles having a size of about 1-1000 nm are dispersed mainly by the action of Van der Waals forces or surface charges without being precipitated, because the action of attraction or gravity on the particles is negligibly small. The sol thus formed is converted into gel by the removal of solvent (dispersing medium) therefrom. The gel, which has no fluidity unlike the sol, is heat-treated to make general ceramics.

In the present invention, before the block copolymer film is formed on the oxide substrates, a neutral layer may also be formed on the oxide substrate. Herein, the neutral layer functions to allow self-assembled nanostructures, which are formed in the block copolymer formed thereon, to stably grow in vertical direction.

When the block copolymer is heat-treated, it is self-assembled to form nanostructures. When the composition ratio of the block copolymer is changed, nanostructures having various shapes can be fabricated. In other words, the shapes of the fabricated nanostructures vary depending on the composition ratio of the block copolymer.

Accordingly, block copolymers having different composition ratios can bind to the organic monolayer film, and the resulting organic polymer materials can be widely used in molds for electrical/electronic parts, sensors, catalysts and other useful applications.

In the present invention, because the conductive oxide used in the fabrication of the nanostructures functions as electrodes, nanostructures having a high aspect ratio can be fabricated without providing electrodes, which are required to control nanostructures using an electric field in the prior art. Also, because it is possible to form nanostructures, which have various shapes depending on the composition ratio of the block copolymer, the nanostructures having various shapes can be applied to molds for the fabrication of nanowire transistors and memory devices, such as FeRAM, MRAM and PRAM, molds for electrical/electronic parts, such as nanostructures for patterning nanoscale wires, molds for the preparation of catalysts for solar cells and fuel cells, and molds for the fabrication of etching masks and organic light-emitting diodes (OLEDs).

Hereinafter, the present invention will be described in further detail with reference to the accompanying drawings.

FIG. 1 shows various nanostructures formed according to the composition ratios of block copolymers. FIG. l(a) is a phase diagram of a self-assembled diblock copolymer nanostructure, predicted according to a self-consistent mean field theory, and FIG. l(b) is a phase diagram of a self-assembled diblock copolymer nanostructure, experimentally verified according to Example of the present invention, and FIG. l(c) shows self-assembled diblock copolymer nanostructures formed according to the relative composition ratios of two blocks. In FIG. l(a), N indicates the degree of polymerization, χ indicates the segment interaction between two blocks, A indicates a polymer block other than polystyrene (PS) in a diblock copolymer (other than PS-b-PS), B indicates the PS block of the diblock copolymer, and f_A and f_B indicate the relative composition ratios of the blocks A and B, respectively.

As shown in FIG. l(a), if χN is less than 10, the block copolymer is formed in a disordered fashion, and if χN is more than 10 but less than 100, a spherical nanostructure having a body centered cubic structure surrounded by the block B is formed, when f_A = N_A/(N_A+N_B) is equal to or less than about 0.18-0.23. Also, if f_A is equal to or less than about 0.30-0.35, the spherical nanodomain forms a cylindrical nanostructure with a hexagonal lattice, and if f_A is between 0.35 and 0.40, a gyroid nanostructure, in which the cylindrical structures are continuously linked in pairs, is formed. Finally, if f_A is about 0.5, a lamellar nanostructure is formed.

In connection with this, if f_B = N_B/(N_A+N_B) is equal to or less than about 0.18-0.23, a spherical nanostructure having a body centered cubic structure, surrounded by the block A, is formed. Also, if f_B is equal to or less than about 0.30-0.35, the spherical nanodomain forms a cylindrical nanostructure with a hexagonal lattice. If f_B is between 0.35 and 0.40, a gyroid nanostructure, in which the cylindrical structures are continuously linked in pairs, is formed. Finally, if f_B is about 0.5, a lamellar nanostructure is formed.

FIG. l(b) according to Example of the present invention shows patterns similar to those of FIG. l(a), and thus it will be obvious to those skilled in the art that the results shown in FIG. l(b) according to Example of the present invention are included in the results shown in FIG. l(a). In Example of the present invention, it was found that, when the composition ratio of polystyrene: polymer other than polystyrene was about 0.5:0.5, a lamellar nanostructure was fabricated, and when the composition ratio was about 0.70- 0.65:0.30-0.35 or about 0.30-0.35:0.70-0.65, a cylindrical nanostructure was fabricated.

In addition, it will be obvious to those skilled in the art, when the composition ratio of polystyrene: polymer other than polystyrene is about 0.65-0.60:0.35-0.40 or about 0.35-0.40:0.65-0.60 and when it is about 0.82-0.77:0.18-0.23 or about 0.18- 0.23:0.82-0.77, a gyroid nanostructure and a spherical nanostructure can be fabricated, respectively, as shown in FIG. 1.

Examples

Hereinafter, the present invention will be described in further detail with reference to examples. It is to be understood, however, that these examples are for illustrative purposes only and are not to be construed to limit the scope of the present invention.

Example 1 : Fabrication of nanostructure comprising organic monolayer and block copolymer using platinum (Pt) substrate

Platinum was deposited on a silicon (Si) substrate by DC sputtering to prepare a platinum substrate having a 500-nm-thick film formed thereon. To remove impurities from the surface of the prepared platinum substrate, the platinum substrate was cleaned using an SC-I (Standard Clean- 1) method. Herein, the SC- 1 method consisted of the steps of: sonicating the substrate in dichloromethane for 10 seconds; treating the substrate in methanol and deionized water in the same manner as described above; and treating the substrate in a mixed solution of water, hydrogen peroxide and ammonia water (5: 1 : 1) at 100 °C for 1 hour. The cleaned platinum substrate was spin-coated with PS-r-PMMA (polystyrene-r- methyl methacrylate), and then heat-treated at 160 °C for 48 hours to form an organic monolayer. The organic monolayer was cleaned with toluene, thus forming a neutral surface consisting of an organic monolayer having a thickness of about 6 nm.

The organic monolayer was spin-coated with a block copolymer PS-b- PMMA(polystyrene-b-methyl methacrylate) and heat-treated at 190 ^°C for 48 hours to form a block copolymer film having a self-assembled nanostructure, thus obtaining a nanostructure comprising the organic monolayer film and the block copolymer film. Herein, the molecular weights of the PS and PMMA blocks of the block copolymer PS-b-PMMA were 25,000 (PS) and 26,000 (PMMA), and the f_A of PMMA was about 0.5.

The upper portion of the nanostructure, comprising the organic monolayer and the block copolymer film, was observed with a scanning electron microscope. As a result, as shown in FIG. 2, it was observed that a nanostructure, comprising a PS matrix and PMMA lamella, was formed.

Example 2: Fabrication of nanostructure comprising organic monolayer and block copolymer using titanium dioxide (TiO?) substrate

Titanium dioxide was deposited on a silicon (Si) substrate by atomic layer deposition to prepare a titanium dioxide substrate having a 100-nm-thick titanium dioxide film formed thereon. To remove impurities from the surface of the prepared titanium dioxide substrate, the titanium dioxide substrate was cleaned by the SC-I (Standard Clean- 1) method.

The cleaned TiO₂ substrate was spin-coated with PS-r-PMMA, and then heat- treated at 160 °C for 48 hours to form an organic monolayer. The organic monolayer was cleaned with toluene, thus forming a neutral surface consisting of an organic monolayer having a thickness of about 6 nm.

The organic monolayer was spin-coated with a block copolymer PS-b- PMMA(polystyrene-b-methyl methacrylate) and heat-treated at 190 °C for 48 hours to form a block copolymer film having a self-assembled nanostructure, thus obtaining a nanostructure comprising the organic monolayer film and the block copolymer film. Herein, the molecular weights of the PS and PMMA blocks of the block copolymer PS-b-PMMA were 25,000 (PS) and 26,000 (PMMA), and the f_A of PMMA was about 0.5.

The upper portion of the nanostructure, comprising the organic monolayer and the block copolymer film, was observed with a scanning electron microscope. As a result, as shown in FIG. 3, it was observed that a nanostructure, comprising a PS matrix and lamellar PMMA, was formed.

Example 3 : Fabrication of nanostructure comprising organic monolayer and block copolymer using ruthenium (Ru) substrate

Ruthenium was deposited on a silicon (Si) substrate by atomic layer deposition to prepare a ruthenium substrate having a 100-nm-thick ruthenium film formed thereon. To remove impurities from the surface of the prepared ruthenium substrate, the ruthenium substrate was cleaned using a piranha treatment method. Herein, the piranha treatment method was carried out through a step of treating the substrate in a mixed solution of sulfuric acid and hydrogen peroxide (about 7:3) at 110 ^°C for 1 hour.

The cleaned Ru substrate was spin-coated with PS-r-PMMA, and then heat-treated at 160 "C for 48 hours to form an organic monolayer. The organic monolayer was cleaned with toluene, thus forming a neutral surface consisting of an organic monolayer having a thickness of about 6 nm.

The organic monolayer was spin-coated with a block copolymer PS-b- PMMA(polystyrene-b-methyl methacrylate) and heat-treated at 190^°C for 48 hours to form a block copolymer film having a self-assembled nanostructure, thus obtaining a nanostructure comprising the organic monolayer film and the block copolymer film. Herein, the molecular weights of the PS and PMMA blocks of the block copolymer PS-b-PMMA were 25,000 (PS) and 26,000 (PMMA), and the f_A of PMMA was about 0.5.

The upper portion of the nanostructure, comprising the organic monolayer and the block copolymer film, was observed with a scanning electron microscope. As a result, as shown in FIG. 4, it was observed that a nanostructure, comprising a PS matrix and lamellar PMMA, was formed.

Example 4: Fabrication of nanostructure comprising organic monolayer and block copolymer using iridium (Ir) substrate

Iridium was deposited on a silicon (Si) substrate by atomic layer deposition to prepare an iridium substrate having a 100-nm-thick iridium film formed thereon. To remove impurities from the surface of the prepared iridium substrate, the iridium substrate was cleaned using the SC-I (Standard Clean- 1) method.

The cleaned Ir substrate was spin-coated with PS-r-PMMA, and then heat-treated at 160 ^°C for 48 hours to form an organic monolayer. The organic monolayer was cleaned with toluene, thus forming a neutral surface consisting of an organic monolayer having a thickness of about 6 nm.

The upper portion of the nanostructure, comprising the organic monolayer and the block copolymer film, was observed with a scanning electron microscope. As a result, as shown in FIG. 4, it was observed that a nanostructure, comprising a PS matrix and a lamellar PMMA, was formed.

Example 5 : Fabrication of nanostructure comprising organic monolayer and block copolymer using zinc aluminum oxide (Zn-Al-O) substrate

Zn-Al-O was deposited on a silicon (Si) substrate by DC sputtering to prepare a Zn-Al-O substrate having a 500-nm-thick Zn-Al-O film formed thereon. To remove impurities from the surface of the prepared Zn-Al-O substrate, the Zn-Al-O substrate was cleaned using the SC-I method.

The cleaned Zn-Al-O substrate was spin-coated with PS-r-PMMA, and then heat- treated at 160 ^°C for 48 hours to form an organic monolayer. The organic monolayer was cleaned with toluene, thus forming a neutral surface consisting of an organic monolayer having a thickness of about 6 nm.

Example 6: Fabrication of nanostructure comprising organic monolayer and block copolymer using niobium-doped strontium tantalate (Nb-SrTiOQ

To remove impurities from the surface of a Nb-SrTiO₃ single-crystal substrate (CYSTEC) prepared through a single-crystal growth method, the Nb-SrTiO₃ single- crystal substrate was cleaned using the SC-I method.

The cleaned Nb-SrTiO₃ substrate was spin-coated with PS-r-PMMA, and then heat- treated at 160 "C for 48 hours to form an organic monolayer. The organic monolayer was cleaned with toluene, thus forming a neutral surface consisting of an organic monolayer having a thickness of about 6 nm.

The organic monolayer was spin-coated with a block copolymer PS-b- PMMA (poly styrene-b-methyl methacrylate) and heat-treated at 190 °C for 48 hours to form a block copolymer film having a self-assembled nanostructure, thus obtaining a nanostructure comprising the organic monolayer film and the block copolymer film. Herein, the molecular weights of the PS and PMMA blocks of the block copolymer PS-b-PMMA were 46,000 (PS) and 21,000 (PMMA), and the f_A of PMMA was about 0.31.

The upper portion of the nanostructure, comprising the organic monolayer and the block copolymer film, was observed with a scanning electron microscope. As a result, as shown in FIG. 4, it was observed that a nanostructure, comprising a PS matrix and cylindrical PMMA, was formed.

INDUSTRIALAPPLICABILITY

As described above, the present invention ha an effect to provide nanostructures, comprising block copolymer nanostructures formed on various oxide substrates. Because the shapes of the block copolymer nanostructures vary depending on the relative composition ratios of blocks forming the block copolymer used in the fabrication of the nanostructures, the nanostructures having various shapes can be used in various applications.

Although the present invention has been described in detail with reference to the specific features, it will be apparent to those skilled in the art that this description is only for a preferred embodiment and does not limit the scope of the present invention. Thus, the substantial scope of the present invention will be defined by the appended claims and equivalents thereof.

Claims

THE CLAIMSWhat is Claimed is:

1. A method for fabricating a block copolymer nanostructure, comprising the steps of:

(a) forming an oxide substrate;

(b) forming a block copolymer film on the surface of the oxide substrate; and

(c) heat-treating the block copolymer to form a self-assembled nanostructure.

2. The method for fabricating a block copolymer nanostructure according to claim

1, wherein the oxide in the step (a) is conductive oxide or nonconductive oxide.

3. The method for fabricating a block copolymer nanostructure according to claim 2, wherein the conductive oxide is a binary conductive oxide or a ternary conductive oxide.

4. The method for fabricating a block copolymer nanostructure according to claim 3, wherein the binary conductive oxide is selected from the group consisting of RuO_x, PdO_x, IrO_x, PtO_x, OsO_x, RhO_x, ReO_x and ZnO_x.

5. The method for fabricating a block copolymer nanostructure according to claim 3, wherein the ternary conductive oxide is selected from the group consisting of SrRuO₃, In_1-xSn_xO₃, Na_xW_1-xO₃, Zn_x(Al₅Mn) _I-XO and Lao.₅Sro.₅CoO₃.

6. The method for fabricating a block copolymer nanostructure according to claim

2, wherein the nonconductive oxide is a binary nonconductive oxide or a ternary nonconductive oxide.

7. The method for fabricating a block copolymer nanostructure according to claim 6, wherein the binary nonconductive oxide is selected from the group consisting of AlO_x, TiO_x, TaO_x, HfO_x, BsO_x, VO_x, MoO_x, SrO_x, NbO_x, MgO_x, SiO_x, FeO_x, CrO_x, NiO_x, CuO_x and ZrO_x.

8. The method for fabricating a block copolymer nanostructure according to claim 6, wherein the ternary nonconductive oxide is selected from the group consisting of SiTiO₃, BaTiO₃, Al_xTi_1-xO_y, HfSi_1-xO_y, HfAl_1-xO_y, TixSi_1-xO_y and LaTiO₃.

9. The method for fabricating a block copolymer nanostructure according to claim

I, which additionally comprises a step of forming a neutral layer on the oxide substrate.

10. The method for fabricating a block copolymer nanostructure according to claim 9, wherein the neutral layer is an organic monolayer or a neutral layer formed using etching.

I 1. The method for fabricating a block copolymer nanostructure according to claim

10, wherein the organic monolayer is selected from the group consisting of a self- assembled monolayer (SAM), a polymer brush and MAT.

12. The method for fabricating a block copolymer nanostructure according to claim

11, wherein the self-assembled monolayer is selected from the group consisting of phenethyltrichlorosilane (PETCS), phenyltrichlorosilane (PTCS), benzyltrichlorosilane (BZTCS), tolyltrichlorosilane (TTCS), 2- [(trimethoxysilyl)ethyl]-2-pyridine (PYRTMS), 4-biphenylyltrimethowysilane (BPTMS), octadecyltrichlorosilane (OTS), 1-naphthyltrimehtoxysilane (NAPTMS), l-[(trimethoxysilyl)methyl]naphthalene (MNATMS) and (9- methylanthracenyl)trimethoxysilane (MANTMS).

13. The method for fabricating a block copolymer nanostructure according to claim 11, wherein the polymer brush is PS-random-PMMA.

14. The method for fabricating a block copolymer nanostructure according to claim 11, wherein the MAT is BCB-functionalized polystyrene-r-poly(methacrylate) copolymer [P(s-r-BCB-r-MMA)].

15. The method for fabricating a block copolymer nanostructure according to claim 10, wherein the neutral layer functions to enable the self-assembled block copolymer nanostructure to grow vertically.

16. The method for fabricating a block copolymer nanostructure according to claim 1, wherein the block copolymer has a structure in which polystyrene and a polymer other than polystyrene are covalently bonded to each other.

17. The method for fabricating a block copolymer nanostructure according to claim 16, wherein the block copolymer is selected from the group consisting of PS-b- PMMA [polystyrene-block-poly(methylmethacrylate)], PS-b-PEO [polystyrene- block-poly(ethylene oxide)], PS-b-PVP [polystyrene-block-poly(vinyl pyridine)], PS-b-PEP [Polystyrene-block-polyCethylene-alt-propylene)] and PS-b- PI[polystyrene-block-polyisoprene].

18. The method for fabricating a block copolymer nanostructure according to claim 16, wherein the composition ratio of polystyrene: polymer other than polystyrene was about 0.5:0.5.

19. A lamellar nanostructure of block copolymer of polystyrene and polymer other than polystyrene, wherein the composition ratio of polystyrene: polymer other than polystyrene was about 0.5:0.5.

20. The method for fabricating a block copolymer nanostructure according to claim 16, wherein the composition ratio of polystyrene: polymer other than polystyrene was about 0.65-0.60:0.35-0.40 or about 0.35-0.40:0.65-0.60.

21. A gyroid nanostructure of block copolymer of polystyrene and polymer other than polystyrene, wherein the composition ratio of polystyrene: polymer other than polystyrene was about 0.65-0.60:0.35-0.40 or about 0.35-0.40:0.65-0.60.

22. The method for fabricating a block copolymer nanostructure according to claim 16, wherein the composition ratio of polystyrene: polymer other than polystyrene was about 0.70-0.65:0.30-0.35 or about 0.30-0.35:0.70-0.65.

23. A cylindrical nanostructure of block copolymer of polystyrene and polymer other than polystyrene, wherein the composition ratio of polystyrene: polymer other than polystyrene was about 0.70-0.65:0.30-0.35 or about 0.30-0.35:0.70-0.65.

24. The method for fabricating a block copolymer nanostructure according to claim 16, wherein the composition ratio of polystyrene: polymer other than polystyrene was about 0.82-0.77:0.18-0.23 or about 0.18-0.23:0.82-0.77.

25. A cylindrical nanostructure of block copolymer of polystyrene and polymer other than polystyrene, wherein the composition ratio of polystyrene: polymer other than polystyrene was about 0.70-0.65:0.30-0.35 or about 0.82-0.77:0.18-0.23 or about 0.18-0.23:0.82-0.77.