JP2003071799A - Nanowire and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a novel nanowire variously applicable in wiring of an electronic or optical integrated circuit or the like by a simple and convenient method. SOLUTION: In the nanowire, ultrafine particles are linearly arranged in a single particle row by using self-organizing structure formation, and its average width is one to five times of an average diameter of the ultrafine particles.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel nanowire and a method for producing the same. More specifically, the present invention relates to a novel nanowire in which ultrafine particles are linearly arranged in a single particle form by utilizing self-organizing structure formation. The nanowire of the present invention is composed of one or more kinds of ultrafine particles and has a structure in which they are linearly connected with a width of nanometer, and can be used as wiring for electronic and optical integrated circuits.

[0002]

2. Description of the Related Art In recent years, ultrafine particles such as metals, semiconductors, oxides, dyes, and conductive polymers having a nano-order size (several nm to tens of nm) {colloidal particles, nanocrystals (Nano
It may also be called a crystal, a nanoparticle, or a quantum dot.
Has attracted attention because it has different physical properties from bulk.
For example, in the case of semiconductor ultrafine particles, carriers generated by light are confined in the particles, resulting in a decrease in particle size and an increase in band gap and exciton energy (eg, Gaponenko, Optical propert
ies of Semiconductor Nanocrystals). In other words, the quantum size effect is exhibited, and confinement of carriers causes an increase in nonlinear optical characteristics, for example, and is expected to be applied to ultrafast optical switching elements. Also, the emission wavelength can be controlled by changing the particle size.
Application to display materials using electroluminescence is also expected. Ultrafine particles such as semiconductor ultrafine particles and metal ultrafine particles can be produced by chemical synthesis, and various organic solvents can be coordinated, adsorbed and bound to the surface of these ultrafine particles to obtain various solvents. Can be dissolved in.

On the other hand, the wiring used in an electronic integrated circuit such as an LSI is made of aluminum and is generally processed into a fine and designed pattern by using photolithography. A dry etching method is known as a method for forming a fine pattern. For example reactive ion beam etching (RIBE)
However, under these circumstances, it is difficult to fabricate nanometer-scale wiring by these methods. If you use a scanning tunneling microscope (STM) or atomic force microscope (AFM) as a method to fabricate a nanometer-scale structure, you can fabricate nanometer-scale wiring, etc., but with a large area. Is not easy.

As a method for producing nanowires, for example, a gold 0.5-1 nm island crystal is grown on a Si wafer by vapor deposition, and a mixed gas of SiH ₄ and He is introduced into the gold to form a catalyst for gold. Can form Si nanowires (Jae- Young et al.,
J. Phys. Chem. B 2000, 104, 11864). In addition, CdSe nanowires, which are semiconductors, were used as pores of alumina (diameter 20 nm, length 28
(mm) has also been reported to be electrochemically synthesized (Dongsheng Xu et al., J. Phys. Chem. B 2000, 104,
5061).

[0005]

An object of the present invention is to provide a novel nanowire having a nanoscale linear structure in which ultrafine particles are arranged in single particles. A further object of the present invention is to produce a novel nanowire which can be applied to various applications such as wiring of electronic and optical integrated circuits by a simple method.

[0006]

As a result of intensive studies to overcome the above-mentioned problems, the inventors of the present invention, for example, utilize the gas-liquid interface to control the spontaneous structure formation conditions,
The present inventors have found that it is possible to manufacture a nanowire having a nanoscale linear structure in which ultrafine particles are arranged in a single particle in a self-organizing manner, and the present invention has been completed.

That is, the present invention provides a novel nanowire in which ultrafine particles form a linear array of single particles. Here, the nanowire formed with a single particle array means that the ultrafine particles have a single particle array in the height direction. The width direction of the single particle array is basically a single particle array, but may be a multiple particle array or may include a multiple particle array portion. The average width of the nanowire of the present invention is usually in the range of 1 to 5 times the average diameter of the ultrafine particles. Specifically, the average diameter (particle diameter) of the ultrafine particles is usually 0.5 to 100 nm, preferably 1 nm to 50 nm.
More preferably, it is 2 nm to 10 nm. The width of the nanowire of the present invention can be appropriately set according to its application, and is preferably 0.5 to 1000 nm.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. As the material of the ultrafine particles forming the nanowire of the present invention, any material can be used without particular limitation as long as it can be dissolved or dispersed in a solvent. However, since the liquid in which the ultrafine particles are dissolved or dispersed in the solvent is dropped onto a liquid surface (subphase) different from the solvent, the ultrafine particles need to be insoluble in the subphase. Specific examples include fine particles or molecules of metals, semiconductors, oxides, dyes, conductive polymers, non-conductive polymers and the like.

Examples of the above metal include Au, Ag,
Pt, Pd, Co, Fe, Ni, Cr, Mn, Al, etc. are mentioned, and an alloy can also be used.

Examples of the above semiconductor include carbon and silicon.
Elemental elements of Group 14 elements of the periodic table, such as elemental, germanium, and tin,
Selenium, a simple substance of periodic table group 15 element such as phosphorus (black phosphorus)
Elemental elements of Group 16 of the Periodic Table of elements such as tungsten and tellurium, silicon carbide
A compound consisting of a plurality of periodic table group 14 elements such as (SiC)
Object, tin oxide (IV) (SnO₂), Tin sulfide (II, IV) (S
n (II) Sn (IV) S₃), Tin sulfide (IV) (SnS₂), Sulfide
Tin (II) (SnS), tin (II) selenide (SnSe),
Tin (II) telluride (SnTe), lead (II) sulfide (Pb)
S), lead (II) selenide (PbSe), lead telluride (I
I) Periodic Table Group 14 elements such as (PbTe) and Periodic Table No. 1
Compound with Group 6 element, Boron Nitride (BN), Boron phosphide
Elemental (BP), Boron Arsenide (BAs), Aluminum Nitride
(AlN), Aluminum phosphide (AlP), Al arsenide
Minium (AlAs), aluminum antimonide (A
1Sb), gallium nitride (GaN), gallium phosphide
(GaP), gallium arsenide (GaAs), antimony
Gallium (GaSb), indium nitride (InN), lithium
Indium Arsenide (InP), Indium Arsenide (InA
s), periodic table of indium antimonide (InSb), etc.
Compound of group 13 element and group 15 element of the periodic table, sulfur sulfide
Luminium (Al₂S₃), Aluminum selenide (Al
₂Se₃), Gallium sulfide (Ga₂S₃), Gallium selenide
Ga (Ga₂Se₃), Gallium telluride (Ga₂Te₃),
Indium oxide (In₂O₃), Indium sulfide (In₂
S₃), Indium selenide (In₂Se₃), Tellurium
Indium (In₂Te₃) Etc. Periodic table group 13 element and period
Compounds with Group 16 elements in the Periodic Table, Thallium (I) chloride (T
lCl), thallium (I) bromide (TlBr), and iodide
Periodic Table Group 13 Elements such as Lithium (I) (TlI) and Periods
Table Compounds with Group 17 elements, zinc oxide (ZnO), sulfurization
Zinc (ZnS), Zinc selenide (ZnSe), Tellurium
Zinc (ZnTe), Cadmium oxide (CdO), Ca sulfide
Cadmium selenide (CdS)
e), cadmium telluride (CdTe), mercury sulfide (H
gS), mercury selenide (HgSe), mercury telluride (H
gTe) etc. Periodic Table Group 12 element and Periodic Table Group 16 element
Compound with arsenic sulfide (III) (As₂S₃), Selenization
Arsenic (III) (As₂Se₃), Arsenic telluride (III) (A
s₂Te₃), Antimony sulfide (III) (Sb₂S₃),
Antimony (III) lenide (Sb₂Se₃), Tellurium
Nchimon (III) (Sb₂Te₃), Bismuth sulfide (III)
(Bi₂S₃), Bismuth selenide (III) (Bi₂S
e₃), Bismuth (III) telluride (Bi₂Te₃) Etc.
Compounds of periodic table group 15 element and periodic table group 16 element, acid
Copper (I) (Cu₂O) and other periodic table group 11 elements and their periods
Table 16 Compounds with Group 16 elements, copper (I) chloride (CuC
l), copper (I) bromide (CuBr), copper (I) iodide (C)
uI), silver chloride (AgCl), silver bromide (AgBr), etc.
A compound of a Group 11 element of the periodic table and a Group 17 element of the periodic table,
Periodic Table Group 10 elements such as nickel oxide (II) (NiO)
Cobalt (II) oxide, a compound of the group 16 elements of the periodic table
Periodic table of (CoO), cobalt (II) sulfide (CoS), etc.
Compounds of Group 9 elements with Group 16 elements of the Periodic Table, Tritetraoxide
Iron (Fe₃O_Four), Iron sulfide (II) (FeS), etc.
Compounds of Group 8 elements and Group 16 elements of the Periodic Table, Manganese oxide
Periodic Table Group 7 elements such as iron (II) (MnO) and Periodic Table 1
Compound with Group 6 element, molybdenum (IV) sulfide (Mo
S₂), Tungsten (IV) oxide (WO₂) Etc. periodic table No.
Compound of Group 6 element and Group 16 element of the periodic table, vanadium oxide
Um (II) (VO), vanadium oxide (IV) (V
O₂), Tantalum oxide (V) (Ta₂O_Five) Etc. periodic table No.
Compound of Group 5 element and Group 16 element of the periodic table, titanium oxide
(TiO₂, Ti₂O_Five, Ti₂O₃, Ti_FiveO₉Etc.) etc.
Compounds of group 4 elements of the periodic table and group 16 elements of the periodic table, sulfurization
Magnesium (MgS), magnesium selenide (Mg
Of elements of Group 2 of the periodic table and elements of Group 16 of the periodic table such as Se)
Compound, Cadmium (II) oxide Chromium (III) (CdC
r₂O_Four), Cadmium selenide (II) Chromium (III)
(CdCr₂Se_Four), Copper (II) sulfide, chromium (III) (C
uCr₂S_Four), Mercury (II) selenide chromium (III) (H
gCr₂Se_Four) Etc. chalcogen spinels, barium chi
Tanate (BaTiO₃) And the like. These half
The conductor may contain elements other than the constituent elements.
Absent.

Examples of the above-mentioned oxide include SiO ₂ and
Examples include TiO ₂ , ZnO, In ₂ O ₃ . Further, these oxides may contain additional elements other than the constituent elements.

Examples of the dye include metal-free phthalocyanine, metal-containing phthalocyanine, perinone pigment,
Examples thereof include organic photoconductive particles such as thioindigo, quinacridone, perylene pigments, anthraquinone pigments, azo pigments, bisazo pigments, trisazo pigments, tetrakis azo pigments, and cyanine pigments. Furthermore, polycyclic quinone,
Various organic pigments and dyes such as pyrylium salt, thiopyrylium salt, indigo, anthanthrone, and pyrantrone can be used.

Examples of non-conductive polymers or conductive polymers include polystyrene-based polymers, polymethylmethacrylate-based polymers, polybutadiene-based polymers, polyvinylpyridine-based polymers, polyisoprene-based polymers, and polycarbonate-based polymers. Examples include molecules, polyphenylene oxide polymers, polyparaphenylene polymers, polyparaphenylene vinylene polymers, polythiophene polymers, polyaniline polymers, polyvinylcarbazole polymers, and copolymers containing them. .

The ultrafine particles of the present invention preferably have the surface of these materials covered with an organic compound by coordination, adsorption or bonding. That is, an organic ligand can be bound to the surface of the particles for the purpose of dispersing them as uniformly as possible without aggregating them. Examples of the organic compound include thiol compounds, amine compounds, phosphoric acid compounds and the like.

The effect of such an organic ligand is particularly large when the ultrafine particles are an inorganic substance such as a salt of a semiconductor, a metal or a transition metal, and is particularly remarkable when the ultrafine particles are a semiconductor or a metal. As a specific structure of the organic ligand, an organic molecule having a mercapto group (or a thiol group; —SH) or a phosphine oxide group (P═O) strongly binds to the surface of the semiconductor or metal ultrafine particles, which is preferable. is there. Also,
For example, Y. Shiraishi et al .; J. Mol. Catal., 141, 187.
As described on page 1 (1999), a coordinating polymer such as polyacrylic acid can also be preferably used as an example of the organic ligand.

The method for producing the nanowire of the present invention includes:
On the surface of the liquid phase, by developing the ultrafine particle-containing liquid in which the ultrafine particles are dispersed or dissolved in a solvent insoluble in the liquid phase,
A method of forming a linear single particle array on the gas-liquid interface in a self-organizing manner can be mentioned. Specifically, for example, the Langmuir-Blodgett method, a method of dropping a dilute solution of a small amount of ultrafine particles dissolved or dispersed on the water surface is used to allow the ultrafine particles to self-assemble on the gas-liquid interface. The single particles can be arranged in a one-dimensional chain. The dropped solution does not dissolve in water, diffuses on the water surface, evaporates only the solvent, and finally only ultrafine particles are formed on the water surface as a single particle layer.

At this time, it is preferable to dilute the concentration of the solution in which the ultrafine particles are used, or to widen the area of the liquid phase that develops, whereby the in-plane of the single particle film formed first is formed. The particle density can be very low. In other words, the particles can be sparsely floating on the water surface. When the operation of narrowing the region of the single particle layer formed on the water surface is further performed, a single particle array having a high particle density is formed although it is a single particle layer. That is, the two-dimensional density of particles increases, and the interaction (eg, dipole interaction, electrostatic interaction, magnetic interaction, etc.) that acts between colliding particles stabilizes the interaction. It is considered that the particles adhere to each other in such a configuration and gradually grow in a linear shape.

Liquid phase that develops ultrafine particles (sub-face)
There is no particular limitation as long as it does not dissolve the ultrafine particles, and, for example, water, an organic solvent, a liquid metal or the like can be used. Specifically, as the organic solvent system, acetone, ethanol, methanol, butanol, toluene,
Xylene, hexane, pyridine, chloroform, carbon tetrachloride, dichloromethane, benzene, dichlorobenzene, tetrahydrofuran, methyl ethyl ketone, N-methylpyrrolidone and the like can be mentioned. Examples of the liquid metal include Hg, Ga, In, Sn and the like.

As a solvent for dissolving or dispersing the ultrafine particles, a solution in which the ultrafine particles are dissolved or dispersed (liquid containing ultrafine particles)
The solvent is not particularly limited as long as it is a solvent different from the liquid phase (sub-phase) in which is added, and examples thereof include water and organic solvents. As the organic solvent, for example, acetone, ethanol,
Methanol, butanol, toluene, xylene, hexane, pyridine, chloroform, carbon tetrachloride, dichloromethane, benzene, dichlorobenzene, tetrahydrofuran, methyl ethyl ketone, N-methylpyrrolidone and the like can be mentioned. Water, an organic solvent and the like may be used alone or as a mixed solvent of two or more kinds. The concentration of ultrafine particles in the ultrafine particle-containing liquid is 0.
It is preferably in the range of 01 mg / ml to 10 mg / ml.

In the present invention, the nanowire in the liquid phase obtained as described above can be further transferred onto a solid substrate. As the transfer method, for example, the solid substrate is horizontally approached to the liquid phase interface on which the nanowires are formed, and after adhering to the single particle layer, the substrate is pulled up substantially horizontally to bring the nanowires on the liquid phase onto the solid substrate. How to transfer,
Pre-immerse the solid substrate at the liquid phase interface at an appropriate angle,
Next, a method of transferring nanowires on the liquid phase onto the solid substrate by forming nanowires on the liquid phase and pulling up the substrate at an appropriate angle, preliminarily immersing the solid substrate horizontally in the liquid phase, and then Examples include a method of forming a nanowire on a liquid phase, lowering the liquid level by draining the liquid from below the container, and depositing the nanowire on a solid substrate to transfer the nanowire.

The solid substrate used in the present invention preferably has an average surface roughness of not more than 1/2 times, more preferably not more than 1/10 times the average diameter of the ultrafine particles to be used. This is preferable because it makes it easy to form a nanowire that is linear and close.

The material of the solid substrate is not particularly limited as long as it is insoluble in the solvent in the mixed solution (liquid containing ultrafine particles) or the solvent constituting the subphase. Specifically, SiO ₂ ,
Semiconductors / insulators such as Si wafers, layered substances such as graphite and mica, metals such as aluminum, aluminum alloys, stainless steel, copper, nickel, gold and silver, metal oxides such as tin oxide and indium tin oxide, and Examples thereof include laminates of these metals and metal oxides, polymer films such as polyester films having a conductive layer of aluminum, copper, palladium, tin oxide, indium oxide or the like on the surface thereof, paper, and the like. Further, a solid substrate on which a pattern is formed by using an inorganic compound or an organic compound having an affinity for the ultrafine particles in the mixed liquid may be used.

Further, a metal, a metal oxide, an organic compound or the like is vapor-deposited and sputtered on a solid substrate, or an organic substance is laminated on the solid substrate by the Langmuir-Blodgett (LB) method or the self-assembly (self-assembly) method. Alternatively, an organic or inorganic multilayer film or an organic / inorganic composite multilayer film can be used as the substrate.

The nanowires of the present invention, in which the ultrafine particles form a linear array of single particles, have various applications as electronic devices such as LSI, wiring of optical integrated circuits, and electron generation sources for field emission displays. It is possible.

[0025]

EXAMPLES The concrete contents of the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Example 1 Pure water was put in a Langmuir trough, and about 0.
8 mg of TOPO (trioctylphosphine oxide) -coated CdSe nanoparticles (average diameter 5 nm) was added to chloroform 1
It is dissolved in ml and 100 ml of the solution is dropped on the water surface using a microsyringe. After dropping, evaporate the solvent,
The single particle layer is gradually compressed using the barrier. Next, the barrier was stopped, and the single particle layer formed on the water surface by the horizontal attachment method was transferred to the Si wafer substrate.

Atomic force microscope (AFM) observation was performed to confirm the structure of the produced film. AF in Figure 1
M shows the surface structure of the single particle film observed. As described above, it was found that the linear structure was formed on the Si substrate. The height of this wire is about 5 nm, which corresponds to the diameter of one ultrafine particle, and the wire seen in these is considered to be a single particle layer. The width of this wire is about 50
was nm. When the cross-sectional profile of the arrowed area shown in FIG. 1 was viewed, it was confirmed that it had a single mountain shape (FIG. 2). On the other hand, when the structure of this wire was examined in detail, a region with a width of about 90 nm was found in one wire, and its cross-sectional profile showed that two peaks were overlapped. , It was found that the cross-sectional profile of the portion having a width of about 50 nm was different. Also A
Considering that the lateral resolution is about several tens of nm due to the shape of the FM probe, it is considered from the above results that the wire of FIG. 1 is a wire in which single particles are connected in a beaded shape. To be

[0028]

INDUSTRIAL APPLICABILITY The nanowire of the present invention has a structure in which ultrafine particles are linearly arranged in a single particle, and the width thereof is 1 to 5 times the average diameter of the ultrafine particles. When the nanowire can be used as an optical waveguide, it is expected to be applied to the wiring of an electronic integrated circuit such as an LSI. Further, the nanowire of the present invention can be easily manufactured by forming it in a self-organizing manner by utilizing a gas-liquid interface.

[Brief description of drawings]

FIG. 1 is a photograph of a CdSe nanowire on a Si wafer observed by an atomic force microscope.

FIG. 2 is a diagram showing a cross-sectional shape of an arrow portion of the CdSe nanowire shown in FIG.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tadashi Kamiya             1000 Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa             Within Mitsubishi Chemical Corporation (72) Inventor Masahiko Hara             2-1, Hirosawa, Wako-shi, Saitama RIKEN             Within (72) Inventor Fumio Nakamura             2-1, Hirosawa, Wako-shi, Saitama RIKEN             Within

Claims (11)

[Claims] 1. A nanowire comprising ultrafine particles forming a linear array of single particles, the average width of which is 1 to 5 times the average diameter of the ultrafine particles. 2. The ultrafine particles have an average diameter of 0.5 to 100 n.
The nanowire according to claim 1, which is in the range of m. 3. The width of the nanowire is 0.5 to 1000 n.
The nanowire according to claim 1 or 2, wherein m and length are in the range of 5 nm to 10000 nm. 4. The nanowire according to claim 1, wherein the ultrafine particles contain at least one selected from metals, semiconductors, oxides, dyes and polymers. 5. The nanowire according to claim 1, wherein the ultrafine particles have an organic compound coordinated, adsorbed or bonded on the surface thereof. 6. The method according to claim 1, further comprising: developing an ultrafine particle-containing liquid in which ultrafine particles are dispersed or dissolved in a solvent insoluble in the liquid phase, on the surface of the liquid phase. Manufacturing method of nanowire. 7. The method for producing a nanowire according to claim 6, wherein at least one selected from water, an organic solvent and a liquid metal is used as a liquid phase. 8. The method for producing a nanowire according to claim 6, wherein at least one selected from water and an organic solvent is used as a solvent for the ultrafine particle-containing liquid. 9. The concentration of ultrafine particles in the ultrafine particle-containing liquid is
The method for producing a nanowire according to any one of claims 6 to 8, wherein the range is 0.01 mg / ml to 10 mg / ml. 10. After spreading the liquid containing ultrafine particles on the surface of the liquid phase,
The method for producing a nanowire according to claim 6, further comprising transferring the nanowire formed on the surface of the liquid phase onto a solid substrate. 11. The method for producing a nanowire according to claim 10, wherein the solid substrate has an average surface roughness of ½ times or less the average diameter of the ultrafine particles used.