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WO2006120780A1 - Agrégat de nanotubes de carbone et son procédé de fabrication - Google Patents

Agrégat de nanotubes de carbone et son procédé de fabrication Download PDF

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Publication number
WO2006120780A1
WO2006120780A1 PCT/JP2006/300981 JP2006300981W WO2006120780A1 WO 2006120780 A1 WO2006120780 A1 WO 2006120780A1 JP 2006300981 W JP2006300981 W JP 2006300981W WO 2006120780 A1 WO2006120780 A1 WO 2006120780A1
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WIPO (PCT)
Prior art keywords
carbon nanotube
carbon nanotubes
aggregate
substrate
carbon
Prior art date
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PCT/JP2006/300981
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English (en)
Japanese (ja)
Inventor
Masaru Hori
Mineo Hiramatsu
Hiroyuki Kano
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NU Eco Engineering Co Ltd
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NU Eco Engineering Co Ltd
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Publication of WO2006120780A1 publication Critical patent/WO2006120780A1/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/158—Carbon nanotubes
    • C01B32/16—Preparation
    • C01B32/162—Preparation characterised by catalysts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/30—Cold cathodes, e.g. field-emissive cathode
    • H01J1/304—Field-emissive cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32055—Arc discharge
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/022—Manufacture of electrodes or electrode systems of cold cathodes
    • H01J9/025—Manufacture of electrodes or electrode systems of cold cathodes of field emission cathodes
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2202/00—Structure or properties of carbon nanotubes
    • C01B2202/20—Nanotubes characterized by their properties
    • C01B2202/36—Diameter

Definitions

  • Carbon nanotube aggregate and method for producing the same
  • the present invention relates to a carbon nanotube aggregate and a method for producing the same.
  • This carbon nanotube has a shape in which a graphite sheet is rounded into a cylindrical shape, and is classified into a single-walled carbon nanotube with a single sheet and a multi-walled carbon nanotube in which a plurality of sheets are nested. be able to.
  • Patent Documents 1 and 2 below disclose the use of carbon nanotubes for wiring between stages of an electronic device.
  • transition metal particles having a particle size of 0.4 to 20 nm are formed on the bottom surface of a via hole by electroless plating, and this is used as a catalyst to form a via hole.
  • carbon nanotubes are grown by a plasma CVD method or the like.
  • Patent Document 2 discloses a method of selectively forming a carbon nanotube at the bottom of a high aspect ratio via hole.
  • a flow of fine particles is obtained parallel to the height direction of the via hole, and Ni nanoparticles having a particle size of 5 nm are formed at the bottom of the via hole.
  • This is a method for growing carbon nanotubes using this as a catalyst.
  • Patent Document 3 discloses a method of forming an ultrafine Si thin film by sputtering using helicon plasma, although it is not a method of forming carbon nanotubes.
  • Patent Document 4 discloses a sharp end multi-walled carbon nanotube radial assembly in which a plurality of spire-shaped multi-walled carbon nanotubes and a common root portion are gathered radially.
  • Patent Document 1 JP 2005-72171
  • Patent Document 2 JP 2005-22886
  • Patent Document 3 JP 2002-167671
  • Patent Document 4 JP 2003-206116
  • Patent Documents 1 and 2 are formed in parallel and cannot be used as a force field emission electrode, which can be used as a wiring. Further, Patent Document 4 discloses use as a field emission electrode.
  • the force-bonn nanotube of this document is essentially a multi-walled carbon nanotube with a large number of layers, and has a sharp tip. Is.
  • the present invention is a force-bonn nanotube aggregate having a completely new structure that has never existed so far.
  • the field emission effect can be enhanced, and application to other fields is expected.
  • an object of the present invention is to provide a carbon nanotube aggregate having a novel structure.
  • the invention of claim 1 is a carbon nanotube aggregate in which tips of a plurality of carbon nanotubes are aggregated in a conical shape.
  • the portion excluding the tip of the carbon nanotube is substantially the same as the base. 2.
  • the roots and intermediate portions of the plurality of carbon nanotubes are formed substantially perpendicular to the substrate and are formed in parallel to each other, and the tip portions of the plurality of carbon nanotubes are assembled in a dot shape. .
  • the invention of claim 3 is the carbon nanotube aggregate according to claim 1 or claim 2, wherein the carbon nanotube is a single-layer or a double-wall.
  • each carbon nanotube constituting the aggregate is a single wall or a double wall. With this structure, it becomes easy to gather the tip portions in a dot shape.
  • the invention of claim 4 is characterized in that the carbon nanotubes are formed by a particulate catalyst having a particle diameter of 5 nm or less formed on a substrate.
  • the aggregate of carbon nanotubes according to any one of the above items.
  • the particulate catalyst formed on the substrate is characterized by a particle size of 5 nm or less. With this configuration, it is easy to gather the tip portions in a dot shape.
  • the invention of claim 5 is characterized in that the carbon nanotube is formed by a particulate catalyst having a particle diameter of 2 nm or more and 4 nm or less formed on a substrate. Or an aggregate of carbon nanotubes according to item 1.
  • the invention of claim 6 is characterized in that the density of the particulate catalyst is 1 x 10 12 m 2 to 5 x 10 13 m 2.
  • a desirable range of the density of the particulate catalyst is 3 ⁇ 10 12 111 2 to 3 ⁇ 10 13 111 2 .
  • a more desirable range is 1 10 13 01 2 to 3 10 13 01 2 . In this desirable range, a high-quality force-bonbon nanotube aggregate in which the tips of a plurality of carbon nanotubes are gathered in a conical shape can be reliably obtained.
  • the invention of claim 7 is the aggregate of carbon nanotubes according to claims 1 to 6, wherein the diameter of the carbon nanotube is 2 nm or more and 5 nm or less.
  • the average outer diameter of the carbon nanotube is 4 nm and the average inner diameter is 3 nm.
  • a particulate catalyst having a particle size of 5 nm or less is deposited on a substrate in a density range of 1 ⁇ 10 12 m 2 to 5 ⁇ 10 cm 2 , and thereafter, two layers are formed by plasma CVD.
  • it is a method for producing a carbon nanotube aggregate in which single-bonn nanotubes are grown and the tips of a plurality of carbon nanotubes are aggregated into a cone shape.
  • the particle size of the particulate catalyst is 5 nm or less and the density is in the range of 1 x 10 12 m 2 to 5 x 10 13 m 2.
  • a desirable range for the density of the particulate catalyst is 3 10 12 111 2 to 3 10 13 111 2 . Further, the desirable range of the density of the particulate catalyst is 1 ⁇ 10 13 m 2 to 3 ⁇ 10 13 m 2 .
  • the invention of claim 10 the particulate catalyst, 1 in X 10- 4 Torr or less degree of vacuum, the carbon nanotube aggregate according to claim 9, characterized in that it is produced by the pulsed arc plasma It is a manufacturing method.
  • the invention of claim 11 is the method for producing a carbon nanotube aggregate according to claims 9 to 10, wherein the particulate catalyst is cobalt or a cobalt alloy.
  • the gas phase density above the substrate of the particulate catalyst formed by the pulsed arc plasma is measured by absorption spectroscopy, and the particulate matter deposited on the substrate is determined from the measured gas phase density.
  • a laser or a holo-power sword lamp can be used as a light source for absorption spectroscopy.
  • the density of the particulate catalyst deposited on the substrate and the density and number of pulses of the gas phase particulate catalyst scattered in the atmosphere by the pulsed arc plasma (generally, the density of the gas phase particulate catalyst x the number of pulses) Is previously measured.
  • the gas phase particulate catalyst density is measured by absorption spectroscopy, and the number of pulses is controlled so that a predetermined density of the particulate catalyst is obtained on the substrate. To do. Thereby, the desired optimum density of the particulate catalyst can be obtained on the substrate.
  • the pulse width and the pulse voltage It It ’s good to control it.
  • Plasma CVD is a method in which a raw material gas of carbon nanotubes is turned into plasma to form a plasma atmosphere, and carbon nanotubes are grown on the substrate using a particulate catalyst deposited on the substrate.
  • a plasma atmosphere is a state in which at least some of the substances that make up the atmosphere are ionized (ie, charged particles such as ions and electrons of atoms and molecules, and neutral particles such as radicals of atoms and molecules) Atmosphere (in a plasma state)).
  • the carbon nanotube can be formed into a single-walled or double-walled carbon nanotube by forming it with a particulate catalyst having a particle diameter of 5 nm or less formed on the substrate. .
  • the outer diameter of each carbon nanotube can be reduced to 5 nm or less, and the tips can be assembled in the form of dots.
  • the invention of claim 5 is to increase the ratio of single-walled or double-walled carbon nanotubes by forming carbon nanotubes with a particulate catalyst having a particle diameter of 2 nm or more and 4 nm or less formed on a substrate. This makes it possible to make the electrical properties of the carbon nanotube aggregate in which the tip ends gather like dots.
  • the tip portion can be assembled in the form of dots by setting the density of the particulate catalyst to 1 ⁇ 10 12 m 2 to 5 ⁇ 10 13 m 2 .
  • the distance between the target and the substrate it is possible to form a carbon nanotube aggregate in which the tips of a plurality of carbon nanotubes are aggregated in a conical shape.
  • 3 10 12 111 2 to 3 10 13 111 2 it is preferably 1 ⁇ 10 13 111 2 to 3 ⁇ 10 13 111 2 .
  • the tip portions can be assembled in the form of dots.
  • the diameter of the carbon nanotubes is 2 nm or more and 5 nm or less, so that the ratio of single-walled or double-walled carbon nanotubes can be increased, and the tips are gathered in the form of dots. It is possible to make the electrical characteristics of the carbon nanotube aggregate uniform.
  • a particulate catalyst having a particle size of 5 nm or less is deposited on a substrate in a density range of 1 x 10 12 m 2 to 5 x 10 13 / cm 2 , and then plasma CVD
  • a carbon nanotube aggregate in which the tips of a plurality of carbon nanotubes are aggregated in a conical shape.
  • the number of the layers is two or less, it becomes easy to manufacture a carbon nanotube aggregate having a pyramidal shape with aggregated tips.
  • an aggregate of carbon nanotubes whose tips are assembled in a dot shape can be easily and uniformly produced.
  • the density of the particulate catalyst is in the range of 1 X 10 12 / cm 2 to 5 X 10 13 / cm3 ⁇ 4
  • the tips of multiple carbon nanotubes can be conically shaped by adjusting the distance between the target and the substrate. It becomes possible to form aggregated carbon nanotube aggregates.
  • 1 X 10 1 3 111 2 to 3 10 13 1 11 2 is desirable. In this range, it is possible to reliably gather the tips in the form of dots.
  • the particulate catalyst is in the degree of vacuum of 1 X 10- 4 Torr, it is generated by the pulse arc plasma, to less 5nm particle size of the particulate catalyst It is possible to make each carbon nanotube as a single layer or a double layer and to assemble the tips in a dot shape.
  • the gas phase density of the particulate catalyst above the substrate is measured by absorption spectroscopy and the measured value power pulse number is controlled, it is deposited on the substrate. It is possible to accurately control the density of the particulate catalyst to be produced, and it is possible to produce high-quality carbon nanotubes.
  • FIG. 1 is a configuration diagram showing an apparatus for depositing a particulate catalyst.
  • FIG. 2 is a configuration diagram showing the principle of the arc gun of the device.
  • FIG. 3 is a table showing conditions for depositing a buffer layer and a particulate catalyst.
  • FIG. 5 is a configuration diagram showing an apparatus for growing carbon nanotubes.
  • FIG. 6 Measurement diagram showing the relationship between the deposition rate of carbon nanotubes and the number of pulse arcs when depositing Co nanoparticles.
  • FIG. 7 SEM image showing the surface structure of an aggregate of carbon nanotubes grown on a substrate on which a particulate catalyst has been formed by 50 pulse arcs.
  • FIG. 9 SEM image showing the side structure of an aggregate of carbon nanotubes grown on a substrate with a particulate catalyst formed by 50 pulse arcs.
  • FIG. 10 is an SEM image showing the surface structure of a carbon nanotube aggregate grown on a substrate on which a particulate catalyst has been formed by 250 pulsed arcs.
  • FIG. 11 SEM image showing the side structure of an aggregate of carbon nanotubes grown on a substrate with a particulate catalyst formed by 50 pulse arcs.
  • FIG. 12 SEM image of the side of an aggregate of carbon nanotubes with tips gathered in a pyramid shape.
  • FIG. 13 SEM image showing the surface structure of an aggregate of carbon nanotubes grown at 600 ° C on a substrate on which a particulate catalyst has been formed by 50 pulse arcs.
  • FIG. 14 SEM image showing the surface structure of an aggregate of carbon nanotubes grown at 700 ° C for 5 minutes on a substrate with a particulate catalyst formed by 50 pulsed arcs.
  • FIG. 15 TEM image of the side of the carbon nanotube aggregate.
  • FIG. 16 is an SEM image showing the surface structure of a carbon nanotube aggregate grown on a substrate on which a particulate catalyst has been formed by 30 pulse arcs.
  • Gon 26 A schematic diagram showing the relationship between the density of the particulate catalyst and the properties of the carbon nanotubes formed.
  • a raw material used for the production of carbon nanotubes various substances having at least carbon as a constituent element can be selected.
  • the elements that can form the source material together with carbon include one or more selected from hydrogen, fluorine, chlorine, bromine, nitrogen, oxygen, and the like.
  • Preferred raw material materials include a raw material material substantially composed of carbon and hydrogen, a raw material material substantially composed of carbon and fluorine, and a raw material material substantially composed of carbon, hydrogen and fluorine.
  • the Saturated or unsaturated hydrocarbons eg CH
  • a source material that exhibits a gaseous state at normal temperature and pressure.
  • Two or more kinds of materials may be used in any proportion, or only one kind of material may be used as a raw material.
  • the type (composition) of the raw material used may vary depending on the production stage, which may be constant throughout the production stage (for example, the growth process) of carbon nanotubes. Depending on the properties and / or characteristics (for example, electrical characteristics) of the target carbon nanostructure, the type (composition) of the raw material used, the supply method, and the like can be appropriately selected.
  • radical source substance a substance containing at least hydrogen as a constituent element can be preferably used. It is preferable to use a radical source material (radical source gas) that exhibits a gaseous state at normal temperature and pressure.
  • a particularly preferred radical source material is hydrogen gas (H 2). Also, ha
  • Substances that can generate H radicals by decomposition such as id carbon (CH etc.)
  • the plasma atmosphere is formed by converting the raw material into plasma in the reaction chamber.
  • the source material is plasmaized outside the reaction chamber, and the plasma is introduced into the reaction chamber to form a plasma atmosphere in the reaction chamber. Good.
  • radicals are injected into the plasma atmosphere from the outside of the atmosphere. It is preferable to decompose radical source materials in a radical generation chamber outside the chamber forming the reaction chamber to generate radicals, which are then injected into the plasma atmosphere in the reaction chamber. Alternatively, a radical generation chamber in the same chamber as the reaction chamber may be decomposed outside the plasma atmosphere, and radicals generated thereby may be injected into the plasma atmosphere. In short, radicals are generated in a region different from the processing region where film formation or processing is performed by plasma of the raw material, and only these radicals are injected into the cache region to control film formation and processing. Carbon nanotubes may be grown.
  • a preferred method for generating radicals from a radical source material includes a method of irradiating the radical source material with electromagnetic waves.
  • the electromagnetic wave used in this method can be selected from either microphone mouth waves or high-frequency waves (UHF waves, VHF waves, or RF waves). It is particularly preferable to irradiate VH F wave or RF wave.
  • the method it is possible to easily adjust the decomposition strength (radical generation amount) of the radical source material, for example, by changing the frequency and / or the input power. Therefore, there is an advantage that the production conditions of carbon nanotubes (such as the amount of radicals supplied into the plasma atmosphere) can be easily controlled.
  • microwave refers to an electromagnetic wave of about 1 GHz or more.
  • UHF wave refers to electromagnetic waves of about 300 to 3000 MHz
  • VHF waves refers to electromagnetic waves of about 30 to 300 MHz
  • RF waves refers to electromagnetic waves of about 3 to 30 MHz.
  • Another preferred method and method for generating radicals from a radical source material is a method of applying a DC voltage to the radical source material. It is also possible to employ a method of irradiating the radical source material with light (eg, visible light or ultraviolet light), a method of irradiating an electron beam, a method of heating the radical source material, or the like. Alternatively, a member having a catalytic metal may be heated and a radical source material may be brought into contact with the member (ie, by heat and catalysis) to generate a radical. As the catalyst metal for generating radicals, one or more selected from Pt, Pd, W, Mo, Ni and the like can be used.
  • the radicals injected into the plasma atmosphere are at least hydrogen radicals (that is, hydrogen atoms). Child. Hereinafter, it may be referred to as “H radical”. ) Is preferably included. It is preferable to decompose a radical source material containing at least hydrogen as a constituent element to generate H radicals and inject the H radicals into a plasma atmosphere. Particularly preferred as such a radical source material is hydrogen gas (H 2).
  • At least one of the carbon nanotube production conditions is adjusted. It is desirable to do.
  • Examples of manufacturing conditions that can be adjusted based on such radical concentrations include the amount of raw material supplied, the plasma intensity of the raw material (the severity of the plasma conditions), and the injection of radicals (typically H radio canore). Amount and the like.
  • Such production conditions are preferably controlled by feedback of the radical concentration. According to a powerful production method, it is possible to more efficiently produce carbon nanotubes having properties and / or characteristics according to the purpose.
  • a radical emission line that is, a carbon atom emission line
  • the emitted emission line is received, and the radio-canole concentration is measured from the light absorption spectrum.
  • the emission line specific to the carbon radical (carbon atom) can be obtained, for example, by applying appropriate energy to a gas containing at least carbon as a constituent element. It can be configured to emit a light beam specific to a carbon radical (carbon atom).
  • Monitors and control targets are not limited to C, H, and F radicals, and C, CF, CF, CF, and CF (x ⁇ l, y ⁇ l) may be used as target radicals.
  • Examples of manufacturing conditions that can be adjusted based on such measurement results include the amount of raw material supplied, the intensity of plasma of the raw material, the amount of radicals (typically H radicals) injected, the amount of radical source material supplied, Radical strength of the radio-canole source material. Such production conditions are determined based on the radical concentration. It is preferable to control the measurement result by feedback. According to such a production method, it becomes possible to produce carbon nanotubes having properties and / or characteristics according to the purpose homogeneously and more efficiently.
  • the amount of radicals injected into the reaction chamber is determined by measuring radicals, particularly H radicals, in the radical generating chamber for generating radicals to be injected or in the inlet for injecting radicals into the reaction chamber. Therefore, it is desirable to control the supply amount of the radical source material and the electric power applied to the radical source material. In this way, the amount of radicals injected into the reaction chamber, particularly H radicals, can be controlled in real time during the growth process, and high-quality carbon nanotubes can be generated.
  • a member having a metal catalyst (Pt, Pd, W, Mo, Ni, etc.) for generating radicals is disposed facing the radical generation chamber, and radical generating means is provided so that the metal catalyst can be heated.
  • a metal catalyst Pt, Pd, W, Mo, Ni, etc.
  • radical generating means is provided so that the metal catalyst can be heated.
  • a wavy Ni wire can be arranged inside the radical generation chamber. Introduce H as a radionocule source material into contact with the heater that passed a current through the wire.
  • H radicals can be generated by the catalytic action of Ni.
  • the heating temperature of the catalyst metal can be, for example, about 300 to 800 ° C, and is usually preferably about 400 to 600 ° C.
  • the plasma discharge means is preferably configured as a capacitively coupled plasma (CCP) generation mechanism.
  • CCP capacitively coupled plasma
  • transition metals such as Ni, Fe, Co, Pd, and Pt
  • alloys of these transition metals, transition metals and other metals are used.
  • An alloy with a semiconductor can be used.
  • a method for depositing the particulate catalyst on the substrate it is desirable to use a no-less arc plasma deposition method. For example, 10 at 4 Torr or less degree of vacuum, by generating an arc to a target consisting of transition metals such as Co, plasma is generated in the transition metal, particulate catalyst particle size of less than 5nm on a substrate Power to deposit S. To less 10- 4 Torr is to reduce the collision probability of atoms or molecules, in order to reduce the particle size.
  • the substrate is Si
  • catalyst particles and Si are alloyed to form silicide, so it is desirable to form a buffer layer such as TiN or AlO.
  • a buffer layer such as TiN or AlO.
  • CoTi is used for the catalyst particles, it does not react with Si, so that the particulate catalyst can be deposited directly on the Si substrate.
  • a Si substrate was used as a substrate as a base.
  • the coaxial vacuum arc deposition apparatus shown in Fig. 1 deposited a TiN buffer layer on a Si substrate and a particulate catalyst made of Co on the TiN buffer layer.
  • a susceptor 11 is provided in a reaction chamber 10, and a Si substrate 12 is provided thereon. Under the susceptor 11, a halogen lamp 13 for heating the Si substrate 12 is provided.
  • a plasma gun 14 is provided above the reaction chamber 10.
  • FIG. 2 is a principle diagram of the plasma gun 14.
  • a cylindrical cathode 15 is provided at the center, a cylindrical insulator 16 is provided around the cathode 15, and a ring-shaped trigger electrode 17 is provided outside thereof.
  • a cylindrical anode 18 is provided coaxially with the cathode 15 and outside the insulator 16.
  • a target 19 made of Co is provided on the end face of the cathode 15, and a cap 30 is provided on the end face of the target 19.
  • a plate-like insulator 31 is provided on the end face of the trigger one electrode 17.
  • FIG. 3 shows the formation conditions of the TiN buffer layer and the particulate catalyst.
  • a pulsed arc plasma was generated 900 times by applying a voltage.
  • a TiN buffer layer having a thickness of 20 nm was formed on the Si substrate 12.
  • the buffer layer is used to prevent the particulate catalyst and Si from reacting to form silicide.
  • the deposition of the particulate catalyst consisting of Co the temperature of the Si substrate 12 to room temperature, 1 X 10- 5 Torr pressure in the reaction chamber 10 to Nag and scores flow of gas, 30 a pulse voltage : Applied 100 times to generate pulsed arc plasma.
  • Co nanoparticles having a particle diameter of 5 nm or less were deposited on the TiN buffer layer in the range of 1 ⁇ 10 12 m 2 to 5 ⁇ 10 13 111 2 .
  • Figure 4 shows the substrate surface when Co particles are deposited on the substrate using 10 pulsed arcs.
  • An atomic force microscope image (AFM image) is shown. From this image, the particle size was determined to be 2-3 nm and the density was 3 ⁇ 10 12 m 2 . Therefore, it was found that the density of Co nanoparticles deposited in a single no-arc was 3 X 10 1 cm 2 .
  • a susceptor 21 made of Mo is provided, and a substrate 12 is provided thereon.
  • a carbon heater 22 for heating the substrate 12 is provided under the susceptor 21.
  • a 2.45 GHz microwave is introduced into the reaction chamber 20.
  • the reaction chamber 20 is provided with an exhaust port 24, which is evacuated by a vacuum pump so that a certain degree of vacuum can be obtained in the reaction chamber 20.
  • H and CH gas are introduced into the reaction chamber 20 via the mass flow controllers 25 and 26, respectively.
  • Figure 7 shows that after depositing Co particles on the substrate by 50 pulse arcs, substrate temperature 700 ° C, microwave power 900W, pressure 70Torr, CH flow 50sccm, H flow 70sccm, growth time Scattered electrons on the surface when carbon nanotubes are grown for 5 seconds It is the image (SEM image) by a microscope. It can be seen that the tips of a plurality of carbon nanotubes are gathered in the form of dots in a pyramid shape. The density of this pyramid is 3 x 10 8 m 2 , and the average spacing is about 0.5 / im.
  • Fig. 8 shows an enlarged image of Fig. 7.
  • Figure 9 shows the side SEM images.
  • the carbon nanotubes grow almost perpendicular to the substrate and the tips are gathered in a cone shape.
  • self-organization in which the tips gather in a cone shape can be seen from the initial stage of growth. Accordingly, it was found that pyramid-like self-organization occurred in the early stage of growth, and then the carbon nanotubes grew perpendicularly to the substrate from the root.
  • FIG. 12 shows an SEM image of the side surface of the carbon nanotube aggregate with the tips assembled in a pyramid shape. It can be seen that the tip forming the pyramid grows straight, but the other intermediate and root portions are twisted and bent perpendicular to the substrate.
  • the growth temperature of the carbon nanotubes was changed.
  • the growth temperature was 700 ° C. Only the growth temperature was 600 ° C, and the other growth conditions were the same, and the carbon nanotubes were grown.
  • Figure 13 shows the SEM image of the surface at that time. It can be seen that the aggregate of carbon nanotubes whose tips are gathered in a pyramid shape is obtained uniformly.
  • Fig. 14 shows the SEM image of the surface when carbon nanotubes were grown with a growth time of 5 seconds and a force of 5 minutes.
  • Figure 15 shows an image (TEM image) obtained by a scanning electron microscope. Even if the growth time is lengthened, once the pyramid is formed, a carbon nanotube aggregate is obtained in which the tips of the middle part and the root part that do not disappear are gathered in a conical shape. Is understood.
  • FIG. 16 SEM images of the respective surface when grown carbon nano tube To Figure 20.
  • the number of panoramic arcs is 30 to 100, a carbon nanotube aggregate in which the tips are gathered in the shape of dots in a cone shape is observed. It can be seen that the density of the aggregate increases as the density of Co nanoparticles increases. However, as shown in Fig. 20, when the panoramic arc reaches 200 times, it can be seen that pyramid-like self-organization has not occurred.
  • the number of pulse arcs was changed in various ways, and as a result of imaging the growth rate of the carbon nanotube and the SEM image of the surface, the pulse arc of about 3 to 150 times was obtained. It was found that pyramid-like self-organization occurs when Co particles are deposited by the above method.
  • the reason for the formation of the pyramid-shaped carbon nanotube aggregate in which the tips are gathered in a conical shape in the form of a dot is considered as follows.
  • the particle size is also small as 2-3 nm, and the diameter of the carbon nanotubes that grow using it as a catalyst is also small, so each carbon nanotube cannot stand independently and grow
  • the tip is considered to be integrated into a cone shape under the Van der Waals force.
  • the aggregate stands on the substrate with a large number of carbon nanotubes as a large number of legs, so that the mechanical strength of the aggregate increases and the tip remains integrated while the root portion is integrated. It seems that the carbon nano tube aggregate with the tip integrated into the pyramid shape is formed.
  • Figure 25 shows a schematic diagram of the growth mechanism at this time.
  • the shape change of the growing carbon nanotubes is considered as follows depending on the number of pulse arcs when depositing Co nanoparticles, and therefore the density of Co nanoparticles. If the density of Co nanoparticles is too low, the distance between adjacent carbon nanotubes is too large and there is no interaction, so it grows randomly and does not grow orderly and perpendicular to the substrate. On the other hand, if the density of Co nanoparticles is too high, the particles themselves will continue to form large lumps, so they will not grow in an orderly manner with respect to the substrate. When the density of Co nanoparticles is appropriate, it is likely that adjacent carbon nanotubes will grow in an orderly manner perpendicular to the substrate and parallel to each other.
  • Figure 26 shows a schematic diagram of the growth mechanism at this time.
  • Such a pyramid-shaped carbon nanotube aggregate in which the tips are gathered in the shape of a cone is a field emission electrode, a field emission electrode array, an interstage wiring of a next generation VLSI, a planar wiring, a fine capacitance, a diode It can also be applied to transistors and the like.
  • the aggregate of carbon nanotubes of the present invention can be used as, for example, a field electron emission electrode, and can be used for displays and other electronic devices.

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  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Composite Materials (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Plasma & Fusion (AREA)
  • Carbon And Carbon Compounds (AREA)
  • Cold Cathode And The Manufacture (AREA)

Abstract

La présente invention concerne un nanotube de carbone de structure innovante. Pour cela, une couche tampon de TiN est placée sur un substrat de Si. Des nanoparticules de Co présentant une taille de particules de 5 nm ou moins sont déposées sur la couche tampon en générant un arc d’impulsion environ 3-150 fois en utilisant un plasma d’arc d’impulsion sous un vide de 1×10-5 Torr. Lorsqu’un nanotube de carbone est ainsi obtenu, un agrégat ponctué pyramidal de nanotubes de carbones présentant un diamètre extérieur moyen de 4 nm et un diamètre intérieur moyen de 3 nm est créé. L’agrégat présente une efficacité d’émission d'électrons de champ élevée.
PCT/JP2006/300981 2005-05-10 2006-01-23 Agrégat de nanotubes de carbone et son procédé de fabrication Ceased WO2006120780A1 (fr)

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JP4872042B2 (ja) * 2005-05-10 2012-02-08 国立大学法人名古屋大学 高密度カーボンナノチューブ集合体及びその製造方法
TWI429585B (zh) * 2006-05-29 2014-03-11 Ulvac Inc Carbon nanotubes growth substrate, carbon nanotubes growth method, carbon nanotubes growth catalyst with particle size control method, and nano-carbon tube diameter control method
JP5081684B2 (ja) * 2008-03-26 2012-11-28 株式会社アルバック カーボンナノチューブ成長用基板及びその製造方法、並びにカーボンナノチューブの製造方法
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JP4621347B2 (ja) * 2000-11-30 2011-01-26 株式会社アルバック ヘリコンプラズマを用いた超微粒子薄膜形成装置
JP3453378B2 (ja) * 2002-01-08 2003-10-06 科学技術振興事業団 鋭端多層カーボンナノチューブ放射状集合体とその製造方法
JP3869394B2 (ja) * 2003-06-30 2007-01-17 富士通株式会社 微粒子の堆積方法及びカーボンナノチューブの形成方法

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Cited By (2)

* Cited by examiner, † Cited by third party
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JP2008234973A (ja) * 2007-03-20 2008-10-02 Ulvac Japan Ltd 電子放出源及びその作製方法並びに画像表示装置の製造方法
JP2012052282A (ja) * 2010-03-02 2012-03-15 Showa Denko Kk 炭素繊維の凝集体

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