JP2000321292A - Nano-tube, nano-tube probe, and their manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain nano-tube probes having the same physical structure at their front end sections by providing sensor sections for ultrafine particles, fullerene, etc., at the front ends of nano-tubes. SOLUTION: A Ni metal film 4 having a thickness of about 10 nm is formed on the surface of a silicon substrate 2 carrying an iron oxide on its surface by vapor deposition and the degree of vacuum in a cylindrical container having a diameter of about 28 mm and a length of about 50 cm is maintained at about 60 Torr by making an He gas to flow in the container at a flow rate of about 50 sccm. When the metallic film 4 is heat-treated for bout one hour by heating the temperature of the film 4 to about 800 deg.C at a temperature-rise rate of about 120 deg.C/min, the film 4 converts to many ultrafine Ni particles 6 having diameters of about 20 nm. When a C6H6 gas is allowed to flow in the container at a flow rate of about 10 sccm for about one hour by maintaining the degree of vacuum at about 60 Torr thereafter, carbon atoms accumulate in the lower ends of the particles 6 due to the dehydration catalytic reaction of the particles 6 and nano-tubes 8 are formed. The nano-tubes 8 grow by pushing up the particles 6 and form carbon nano-tubes 10 having ultrafine particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nanotube probe for manipulating a surface signal of a substance by using a nanotube such as a carbon nanotube, a BCN-based nanotube, or a BN-based nanotube as a probe. The present invention relates to a nanotube probe in which fullerene or the like is provided as a sensor unit, and a surface signal of a substance can be manipulated with high reproducibility with high reproducibility by a sensor unit having a predetermined structure.

[0002]

2. Description of the Related Art Conventionally, there has been an electron microscope as a microscope for observing a sample surface at a high magnification. However, since an electron beam does not fly unless it is in a vacuum, there are various problems in experimental techniques. However, in recent years, a scanning probe microscope technique capable of observing the surface at the atomic level even in the atmosphere has been developed. When the probe at the forefront of the probe is brought very close to the sample surface to the atomic size, the physical and chemical action from each sample atom is detected by the probe, and the detection signal is scanned while the probe is scanned over the surface. This is a microscope that makes a sample surface image appear from the microscope.

[0003] Of these microscopes, those which are particularly frequently used are a scanning tunneling microscope (also abbreviated as STM) and an atomic force microscope (also abbreviated as AFM).
In STM, a conductive probe such as a polished metal needle is used.
FM detects surface signals using a cantilever using a silicon pyramid as a probe. A problem common to all of them is that it is not possible to detect the fine structure at the atomic level on the material surface with high resolution because the tip of the probe cannot be sharpened extremely finely.

For example, FIG. 15 shows a conventional AF made of silicon.
It is a cantilever for M. The back of the cantilever 50 is fixed to a substrate 52, and a pyramid-shaped probe 54 is formed in the front. This pyramid probe 5
An extremely fine sharp portion 56 is formed at the front end of 4, and this sharp portion 56 approaches the material surface to detect surface information. This A
FM cantilevers are manufactured by semiconductor planar technology, but no matter how sharp the sharp part is formed,
It is much larger than the atomic size. Therefore, when the surface information changes with the atom size, there is a limit in detecting the surface information with high accuracy down to the atomic level even by using the above-mentioned probe.

Therefore, in recent years, an idea for using carbon nanotubes for a probe has appeared. Since carbon nanotubes are conductive, they can be used not only for STM for detecting tunnel current but also for AF for detecting atomic force.
Also available for M. J. Am. Chem. Soc. 12
Vol. 0 (1998), p. 603, proposes a carbon nanotube probe as a high-resolution probe for imaging biological systems. However, how to collect only the carbon nanotubes from the carbon mixture and how to fix the carbon nanotubes to the holder have not been solved yet.

Although different from the field of probe microscopes,
In recent years, as the memory capacity of computers has increased, memory devices have been evolving from floppy disk devices to hard disk devices and further to high-density disk devices.
If information is packed more densely in a small space, the size per information becomes smaller, so that a finer input / output probe is required. In the conventional magnetic head device, it was impossible to make the size smaller than a certain value.
There has been a demand for ultra-miniaturized input / output probes for electronic devices such as CD devices.

As an alternative to this magnetic head, FIG.
The magnetic probe shown in FIG. 6 has been considered. This magnetic probe is formed by forming a ferromagnetic metal film 58 on a sharp portion 56 of the pyramid-shaped probe 54 by a vapor deposition method. However, since the ferromagnetic metal film 58 is a polycrystalline film, the ferromagnetic metal film 58 has a film structure in which many magnetic domains 60 are arranged in a complex manner.

FIG. 17 is an explanatory diagram of a case where magnetic information of a target substance is detected by the magnetic probe. When this magnetic probe is brought close to the surface of the target substance 62, the magnetic force is a long-distance force acting according to the inverse square law, so that each magnetic domain detects magnetic information with an intensity proportional to 1 / z ^2. .
As a result, the combined signal becomes magnetic surface information, and it is extremely difficult to detect the magnetic information with high resolution. The problem is that the sharps themselves are quite large at the atomic level and are composed of many magnetic domains.

Therefore, it is naturally conceivable to use the above-described carbon nanotube as the magnetic probe. However, a technique for supporting a ferromagnetic material on carbon nanotubes has not yet been developed. Furthermore, it is the same as described above that the technology for purifying the carbon nanotubes and the technology for immobilizing the carbon nanotubes on the holder are still unsolved.

The present inventors have filed three patent applications that provide a solution to the miniaturization technology among these problems. That is, Japanese Patent Application No. 10-280431 discloses a method for purifying nanotubes by an electrophoresis method.
No. 42 proposed a technique for immobilizing nanotubes using a coating film, and Japanese Patent Application No. 10-378548 completed a technique for immobilizing nanotubes by heat fusion.

[0011]

While the present inventors are further researching nanotube probes, when they are applied to STM, AFM, magnetic probes, etc. using nanotubes as probes, they can be obtained on the same material surface. We have noticed the disadvantage that the signal varies with the nanotube used. This means that the physical or electronic structure at the tip of the nanotube that senses the surface signal is different for each nanotube. In other words, the size of the nanotubes used varies. Although the nanotubes are selected and fixed to the holder in the electron microscope, it is difficult to determine whether or not the nanotubes have the same structure including the size and the electronic structure in the electron microscope image.

Accordingly, a first object of the present invention is to provide a nanotube having the same physical structure and electronic structure at the tip and a method for producing the same. A second object of the present invention is to
An object of the present invention is to provide a nanotube probe capable of reproducing surface information of a target substance with high accuracy by fixing the nanotube having the same tip portion to a holder.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above objects and objects. The invention according to claim 1 is a nanotube characterized in that a sensor portion is provided at the tip of the nanotube. According to a second aspect of the present invention, the sensor section is an ultrafine nanotube. In the invention according to claim 3, the ultrafine particles are nanotubes of ferromagnetic metal ultrafine particles. In the invention according to claim 4, the sensor unit is a fullerene nanotube.

According to a fifth aspect of the present invention, a metal thin film is formed on a substrate, the metal thin film is heated to be converted into ultrafine metal particles, and heated while flowing a carbon compound gas over the ultrafine metal particles. A carbon component forming carbon nanotubes at the root thereof while decomposing the particles and pushing up the ultrafine particles. A sixth aspect of the present invention is a method for producing a nanotube, comprising cutting a required portion of the nanotube and bonding fullerene to the cut surface. The invention of claim 7 is a method for producing a nanotube, in which fullerene is bonded to a closed or opened tip surface of the nanotube.

An eighth aspect of the present invention is a nanotube probe characterized in that a base end portion of a nanotube provided with a sensor portion at a front end is fixed to a holder. In a ninth aspect of the present invention, the sensor unit is a nanoparticle nanotube probe. The invention according to claim 10 is the nanotube probe in which the ultrafine particles are ferromagnetic metal ultrafine particles. Claim 1
In one aspect of the invention, the sensor unit is a fullerene nanotube probe. According to a twelfth aspect of the present invention, there is provided a method for manufacturing a nanotube probe, wherein the base end of the nanotube formed according to the fifth aspect is fixed to a holder. The invention of claim 13 is a method for manufacturing a nanotube probe, wherein the base end of the nanotube formed according to claim 6 or 7 is fixed to a holder.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies to equalize the physical structure and electronic structure of the tip of a nanotube probe, and as a result, separately formed a sensor part having a fixed size and structure at the tip of the nanotube. As a result, the inventors have completed a technique capable of guaranteeing the identity of the sensor unit even if the structure of the nanotube slightly changes. As long as the sensor unit is the same, the material structure and the electronic structure are the same, and the surface information of the target material can be reproduced with high accuracy.

The present inventors have come to the recognition that ultrafine particles or fullerene, which is a soccer ball-like substance, is suitable as a sensor having a predetermined size and substance structure.

Ultrafine particles refer to cluster-like atomic groups having a particle size of several tens of nanometers or less, and various types of ultrafine particles such as metal ultrafine particles, metal oxide ultrafine particles, silicon ultrafine particles, and SiC ultrafine particles are manufactured. . It has been found that ultrafine particles of various particle sizes can be produced in a single crystal state or in a polycrystalline state having strong single crystallinity depending on the production method and production conditions. Therefore, if the production method and the conditions are specified, it is possible to produce ultrafine particles having the same electronic structure and a specific particle size having a single domain. By fixing the ultrafine particles of this specific structure to the tip of the nanotube, it is possible to read the surface information of the target substance with the ultrafine particles and write information on the target substance surface with high reproducibility. .

The ultrafine nanotube probe can be obtained by using a conventional probe microscope such as a scanning tunneling microscope, an atomic force microscope, a friction force microscope, a magnetic force microscope,
It can be used as a probe for chemical force microscope. If ultrafine particles for detecting a specific physical or chemical action are fixed to the tip of the nanotube in accordance with each application, physical and chemical surface information of the target substance can be obtained.

For example, Fe, Co, Ni as ultrafine particles
If the ferromagnetic metal ultrafine particles are used, the magnetism on the surface of the target substance is sensed, so that the magnetic surface structure can be read. Conversely, if these ferromagnetic metal ultrafine particles are used as a magnetic head, it becomes possible to write magnetic information on the surface of the target substance, and it can be used as an input / output probe. The unit size of the magnetic information that can be input and output depends on the size of the ultrafine particles, and can be reduced to several nm or less, and even to 1 nm or less, so that ultra-high density can be achieved. Since the ultrafine particles are extremely small in this way, they are effective for measuring the magnetism of a minute object. For example, iron oxide ultrafine particles such as Fe ₂ O ₃ and Fe ₂ O ₄ can be used for magnetic measurement in biological cells, and the measurement position in cells can be freely and minutely adjusted by using a nanotube probe. Can be.

Further, if ultrafine particles having a catalytic action are used as the sensor section, the nanotube probe can be used as a catalyst probe. For example, Ni ultrafine particles can be used as a hydrogenation catalyst for 1,3-cyclooctadiene, and Cu-ZnO ultrafine particles can be used as a methanol synthesis catalyst. By fixing these ultrafine particles to the nanotubes instead of simply dispersing and dispersing them as a powder, the catalyst arrangement can be accurately adjusted, and the catalyst efficiency can be improved. Further, it can be used as a probe for measuring a catalytic reaction.

At present, there are two methods for fixing ultrafine particles to the tip of a nanotube. The first is a method in which the nanotubes and the ultrafine particles are separately manufactured, and the ultrafine particles are brought extremely close to the tip surface of the nanotube or a cut surface obtained by cutting the tip, and are bonded by an atomic force. Alternatively, there is a method in which a double bond at the tip end surface or cut surface of the nanotube is opened by light irradiation, a chemical reaction, or the like, and the ultrafine particles are chemically bonded to the bonding hand. The joint can be reinforced by irradiating the joint with an electron beam or a laser beam. These series of operations can be performed while directly observing in an electron microscope. The second is,
This is a method in which nanotubes and ultrafine particles are grown simultaneously or before and after. Various methods such as chemical vapor deposition (CVD) used in semiconductor technology can be used for this method. For example, when ultrafine particles are grown on a substrate and then a carbon compound gas is flowed near the surface, carbon molecules grow by thermal decomposition at the root of the ultrafine particles and grow as carbon nanotubes, and at the tip thereof, It will carry fine particles.

Fullerene can be used as the sensor. Fullerene is a generic term for soccer ball-like substances, that is, spherical shell molecules, and is the first in a steam cooled product obtained by irradiating graphite with a high energy laser in 1985.
Issue _C60 was discovered. At present 70-100 atoms
High-quality fullerenes and larger giant fullerenes have been discovered, and their synthesis has been established. These fullerenes are composed of a five-membered ring and a six-membered ring formed by carbon sp ² orbitals, and some of them include a seven-membered ring.

When fullerenes are theoretically considered as figures, Euler's polyhedron theorem shows that 12 five-membered rings are included and that six-membered rings vary with the number of all atoms. It is also considered that the isolated five-membered ring rule that twelve five-membered rings are not adjacent is mathematically satisfied. Considering these mathematical rules, higher fullerenes have C
₇₀ , C ₇₆ , C _78, etc.
It can be seen that ₂₄₀ , C ₅₄₀ , C _{960 and the} like exist. In addition, their existence has been confirmed experimentally.

It has been confirmed that fullerene is contained in large amounts in carbon soot. Therefore, the method for producing fullerene having a specific structure includes a method for producing soot and a method for separating specific fullerene from soot. The method of producing fullerene soot includes a resistance heating method and an arc discharge method, and a direct current arc discharge method is often used. That is, when a DC voltage is applied between the graphite electrodes to cause an arc discharge, fullerenes of various carbon numbers are mixed in the generated soot. Next, the soot is separated by a technique of chromatography. In particular, fullerene having a specific number of carbon atoms can be easily separated by using liquid chromatography or column chromatography.

For example, using a polystyrene column,
By performing high performance liquid chromatography using the developing solution as benzene or carbon disulfide, C ₇₆ , C ₇₈ ,
Fullerenes such as C ₈₂ , C ₈₄ , C ₉₀ and C ₉₆ can be separated. Fullerenes having a fixed number of atoms may be considered to have the same electronic structure except for isomers.
Recently, it has become possible to separate fullerenes of the same size for each structural isomer. By going to this stage, a large number of fullerenes having a specific structure having the same electronic state can be produced. By fixing this fullerene of fixed size and structure to the tip of the nanotube, it is possible to read the surface structure of the target substance with high accuracy and reproducibility regardless of the difference of nanotubes, and it is also possible to write information on the target surface become.

A fullerene containing a metal can also be manufactured. For example, graphite powder and a metal oxide are mixed at an appropriate ratio, and graphite cement is added to the mixture to form a rod-shaped electrode. This rod-shaped electrode was slowly heated in an argon atmosphere, and finally 1200 ° C.
After heating for about 10 hours, the electrode is completed. Arc discharge is performed using this electrode, and the obtained soot is extracted with a solvent to separate fullerene having a specific structure. Metal atoms are confined in this fullerene. There are La, Y, Sc and the like as the metal atom. By changing the metal oxide, a desired metal atom can be included in the fullerene.

There are the following methods for fixing the fullerene having the specific structure to the nanotube. First, nanotubes and fullerenes are manufactured separately. Next, the tip of the nanotube is cut, and fullerene is brought extremely close to the cut surface to be bonded by an atomic force. The joint can be reinforced by irradiating the joint with an electron beam or a laser beam. These series of operations are performed while actually observing in an electron microscope.

In the thus completed nanotube, even if the nanotube has some size variation, since the sensor section for observing the material surface is a fullerene having a specific structure, the same signal is accurately reproduced from the same target surface. can do. Therefore, it is possible to provide a nanotube probe capable of measuring and manipulating a material surface with high accuracy without being affected by variations in the structure of the nanotube.

This fullerene nanotube probe is
It can be used as a probe for existing probe microscopes such as a scanning tunneling microscope, an atomic force microscope, a friction force microscope, a magnetic force microscope, and a chemical force microscope. If fullerenes for detecting specific physical and chemical actions are fixed to the tips of the nanotubes according to each application, physical and chemical surface information of the target substance can be obtained.

Further, by enclosing atoms for detecting specific physical and chemical information in fullerene and fixing the atom-encapsulated fullerene to the nanotube, specific information on the surface of the object can be detected. For example, when a ferromagnetic metal atom such as Fe, Co, or Ni is included, the magnetic structure on the target surface can be detected as in the case of the ultrafine particles described above. Conversely, if the surface of the target substance is a magnetic recording medium, specific information can be written using this fullerene nanotube probe.

The nanotube used in the present invention is a nanotube such as a carbon nanotube, a BCN-based nanotube, and a BN-based nanotube. Among them, carbon nanotubes (hereinafter, also referred to as CNT) were first discovered. Conventionally, diamond, graphite, and amorphous carbon have been known as stable allotropes of carbon. However, in 1991, the presence of carbon nanotubes having a tubular structure was recognized in the cathode deposits generated by the DC arc discharge.

Based on the discovery of this carbon nanotube, a BCN-based nanotube was synthesized. For example, a mixed powder of amorphous boron and graphite is packed in a graphite rod and evaporated in nitrogen gas. Further, the sintered BN rod is packed in a graphite rod and evaporated in helium gas. Further, arc discharge is performed in helium gas using BC ₄ N as an anode and graphite as a cathode. By these methods, BCN-based nanotubes in which C atoms in carbon nanotubes are partially replaced by B atoms and N atoms are synthesized, or multi-walled nanotubes in which BN layers and C layers are concentrically stacked are synthesized.

More recently, BN-based nanotubes have been synthesized. This is a nanotube containing almost no C atoms. For example, carbon nanotubes and B ₂ O
₃ Put the powder in a crucible and heat in nitrogen gas. As a result, it can be converted to a BN-based nanotube in which most of the C atoms in the carbon nanotube are replaced with B atoms and N atoms. Of course, various other nanotubes can also be used.

There are two methods for producing the nanotube probe of the present invention. The first method is to fix the sensor section to the nanotube, and then fix the base end of the nanotube with the sensor section to the holder. Second, fix the base end of the nanotube to the holder first,
Thereafter, the sensor is fixed to the tip of the nanotube.

In order to fix the nanotube to the sensor part, the sensor part is fixed to the tip of the arranged nanotube (or the crystal is grown), or the nanotube is fixed to the arranged sensor part (or the crystal is grown). There is. In particular, the latter includes the case where nanotubes are formed while forming ultrafine particles and pushing up the ultrafine particles.

There are two methods for fixing the base end of the nanotube to the holder. The first method is to transfer the nanotubes onto the holder surface by applying an electric field or Van der Waals force, and fix the base end in contact with the holder surface with a coating film with the tip of the nanotube protruding. is there. The second is a method in which the nanotube is transferred to the holder surface by applying an electric field or Van der Waals force, and the base end portion of the nanotube in contact with the holder surface is thermally fused to the holder surface.

The formation of the sensor-equipped nanotube and its attachment to the holder can be performed simultaneously. Specifically, a metal film is formed on the surface of the silicon pyramid of the cantilever, and further heated to turn the metal film into ultrafine metal particles,
Subsequently, carbon nanotubes are formed so as to push up ultrafine metal particles by flowing a carbon compound gas. In this case, the nanotubes with the sensor are formed at once in the pyramid of the cantilever, and the manufacturing process can be simplified. Among the carbon compounds, hydrocarbons are preferred.

[0039]

EXAMPLES Example 1 Formation of Nanotubes with Ultrafine Particles FIGS. 1A to 1D are process diagrams of a method of forming carbon nanotubes with ultrafine particles, among the nanotubes with ultrafine particles. A 10 nm-thick Ni metal film 4 is formed on the surface of the silicon substrate 2 having the iron oxide surface shown in FIG. 1A by a vapor deposition method (FIG. 1B). This is 28mm in diameter
And put it in a cylindrical container with a length of 50 cm and supply He gas for 50 s.
The degree of vacuum is maintained at 60 mTorr while flowing at a flow rate of ccm. Heating to 800 ° C. at a rate of temperature increase of 120 ° C. per minute and heat-treating for 1 hour, the Ni metal film 4 changes into a large number of Ni ultrafine particles 6 on the silicon substrate 2 as shown in FIG. And its diameter is about 20 nm. Next, the C ₆ H ₆ gas is flowed at a flow rate of 10 sccm for 1 hour without breaking the vacuum and maintaining a vacuum degree of 60 mTorr, and the lower end of the Ni ultra-fine particles 6 is caused by the dehydrogenation catalytic reaction of the Ni ultra-fine particles 6. The carbon atoms accumulate in the carbon nanotubes 8 to form carbon nanotubes 8. This carbon nanotube 8 is made of Ni
The ultrafine particles 6 grow while being pushed up, and the carbon nanotubes 10 with ultrafine particles are formed.

FIG. 2 is a sectional view of the carbon nanotube 10 with ultrafine particles. Diameter d of carbon nanotube 8
Distributed between 15 and 150 nm, with an average of 45 nm. Although the diameter D of the Ni ultrafine particles 6 is slightly larger than the diameter d, the diameter D can be reduced by reducing the thickness of the Ni metal film 4 or shortening the heat treatment time for forming ultrafine particles. There is a method.

FIG. 3 is a process diagram for transferring the carbon nanotubes 10 with ultrafine particles to the pyramid 14 of the cantilever 12 for AFM. In this case, the pyramid 14 becomes a holder for mounting the carbon nanotubes 10 with ultrafine particles. Carbon nanotubes with ultrafine particles 10
A DC electric field is formed by a DC power supply 16 between the silicon substrate 2 on which is formed and the cantilever 12, and the carbon nanotubes 10 with ultrafine particles are pyramid 1
4. Jump to 4. In this case, the ultrafine particles 6 protrude to the tip, and the axis of the carbon nanotube 8 is aligned with the cantilever 12.
And the base end 8 a is adjusted so as to join the pyramid 14. These operations are performed while directly observing in an electron microscope. The direction of the electrodes of the DC power supply 16 is adjusted according to the chargeability of the nanotube.

FIG. 4 is a process diagram for fixing the carbon nanotubes 10 with ultrafine particles to the pyramid 14. When the base end portion 8a of the carbon nanotube 8 is irradiated with the electron beam 16, the base end portion 8a is denatured to become a fusion portion 8b, and is fixed to the pyramid 14 by heat fusion.

FIG. 5 is a diagram showing a magnetizing process of the Ni ultrafine particles 6. In this sample, the nanotube diameter d is 25 nm, N
i The ultrafine particle diameter D is 35 nm, and the tip length L is 400 nm. For this Ni ultrafine particle 6, 1 for only 10 ms.
It magnetizes by applying a pulse magnetic field B of 2.5 Tesla. The Ni ultrafine particles 6 are a single-domain ferromagnetic material, and this pulse magnetization makes it possible to use them as a nanotube probe 16 having a single magnetization domain for high-resolution magnetic detection.

FIG. 6 is a use state diagram of a nanotube probe for high-resolution magnetic detection, and the surface magnetic information 20 of the magnetic recording medium 18 is measured using the nanotube probe 16. The approach distance AD to the surface of the ultrafine particles 6 is 50 to
100 nm is preferred, but set to 80 nm to avoid the effects of Van der Waals forces.

FIG. 7 is a magnetic image of the magnetic recording medium 18 displayed on a computer. Scanning object is 20μm × 20μ
In the area of m, the interval between the magnetic tracks is 1.5 μm.
As described above, it was found that the surface magnetic structure can be revealed in detail by the nanotube probe 16 of the present invention.
Conversely, magnetic information can be written to a magnetic recording medium using the nanotube probe 16. When the surface of the magnetic recording medium is scanned while a magnetic signal is applied to the Ni ultrafine particles 6 by an electronic device (not shown), the magnetic signals are written one after another.

FIG. 8 is a process chart showing another method for fixing the nanotube 8 to the holder. In this case, the holder is a pyramid 14, and a current flows between the nanotube 8 and the cantilever 12 via a power supply 22, and the base end 8a is transformed into a fused portion 8b and fixed to the pyramid.

FIG. 9 is a process chart showing still another fixing method. The electron microscope contains a carbon compound as an impurity. Therefore, when the vicinity of the nanotube is irradiated with the electron beam 16, the carbon compound is decomposed, and a coating film 24 which is a carbon film is deposited and formed on the base end 8 a of the nanotube 8. The carbon nanotubes 8 are firmly fixed to the pyramid 14 by the coating film 24.
As the method for forming the coating film 24, various known methods such as a physical vapor deposition method and a chemical vapor deposition method (CVD method) can be used in addition to the above methods. In this coating film method, since a coating film can be formed on the tip of the carbon nanotubes 8, resonance can be suppressed by increasing the thickness of the carbon nanotubes 8, and the effect of improving accuracy can be obtained.

FIG. 10 is a configuration diagram in which the nanotube probe 16 according to the present invention is applied to an atomic force microscope (AFM). The ultrafine particles at the tip of the nanotube probe 16 abut on the sample surface, and the sample surface information can be accurately read. The nanotube probe 16 is detachably fixed to a holder set (not shown). When the probe is replaced, the entire probe 16 is replaced. In this case, the probe is a nanotube with a sensor. Sample 2
Reference numeral 6 is driven in the XYZ directions by a scan driver 28 composed of piezo elements. Reference numeral 30 denotes a semiconductor laser device, 32 denotes a reflection mirror, 33 denotes a two-segment photodetector, 34 denotes an XYZ scanning circuit, 35 denotes an AFM display device, and 36 denotes a Z-axis detection circuit.

The sample 26 is made to approach the nanotube probe 16 in the Z-axis direction until it reaches a predetermined repulsive position, and then the scanning circuit 34 scans the XY direction by the scanning circuit 34 with the Z position fixed. At this time, the cantilever 12 bends due to the unevenness of the surface atoms, and the reflected laser beam L
B enters the split photodetector 33 with its position displaced. The Z-axis direction displacement is calculated by the Z-axis detection circuit 36 from the difference between the light detection amounts of the upper and lower detectors 33a and 33b, and the displacement amount is displayed on the AFM display device 35 as the amount of atomic irregularities on the AFM display device 35. . In this apparatus, the sample 26 is configured to perform XYZ scanning, but the probe 16 may be configured to perform XYZ scanning.

FIG. 11 is a configuration diagram of a scanning tunneling microscope (STM) to which the nanotube probe according to the present invention is applied. The nanotube 10 with the ultrafine particles is fixed to a flat holder 15 as a probe and attached to the nanotube probe 1.
6 is constituted. The fixing method may be a fusion method, a coating film method or another method. The holder 15 is fitted in the cut groove 17a of the holder setting section 17 and is detachably fixed by spring pressure. The scanning drive unit 28 including the X piezo 28x, the Y piezo 28y, and the Z piezo 28z
Is scanned in the XYZ three-dimensional direction to realize scanning of the nanotube probe 16 on the sample 26. 37 is a bias power supply, 38 is a tunnel current detection circuit, 39 is a Z-axis control circuit, 40 is an STM display device, and 41 is an XY scanning circuit.

The nanotube probe 16 is controlled to expand and contract in the Z direction by the Z-axis control circuit so that the tunnel current is constant at each XY position, and the amount of movement becomes the amount of unevenness in the Z-axis direction. As the nanotube probe 16 is scanned in the X and Y directions, a surface atom image of the sample 26 is displayed on the STM display device 40. In the present invention, when exchanging the nanotube probe, the holder 15 is removed from the holder set portion 17 and exchanged as the probe 16 integrally.

[0052] FIG. 12 is an enlarged view of the fullerene of _{C 60.} This fullerene is composed of 12 pentagons and 20 hexagons, and the isolated five-membered ring rule that the pentagons are not adjacent to each other is established. Larger fullerenes have been found to increase the number of hexagons. If this fullerene is fixed to the tip of the nanotube as a sensor part, a nanotube probe having high resolution can be formed.

FIGS. 13 (A) and 13 (B) are manufacturing process diagrams of a nanotube probe using fullerene as a sensor. The nanotube 8 in the step (A) may be any nanotube such as a CNT-based nanotube, a BCN-based nanotube, and a BN-based nanotube. In the step (B), a required portion of the nanotube 8, mainly a tip portion, is cut. In the step (C), the fullerene 7 is adhered to the cut surface 8c by van der Waals force, and the fullerene-attached nanotube 11 is attached.
To form In order to strengthen this bonding, both can be fused at the joint by electron beam irradiation or current heating.

FIG. 14 shows another method for forming fullerene-attached nanotubes. Normally, the tip of the nanotube 8 is closed, and the double bond is opened at the closed tip using light excitation or a catalyst. Similarly, the fullerene double bond is also opened, and a fullerene-attached nanotube 11 can be formed by connecting both hands. This method can be applied to nanotubes with open ends. Here, the term “opened” includes both the case where it is cut and opened and the case where it is opened in a natural state.

By fixing the base end of the fullerene-attached nanotube 11 to a holder (not shown), a nanotube probe can be formed. As the fixing method, the above-mentioned coating film method, fusion method and the like can be used. If you do this,
Even if the thickness and structure of the nanotube 8 slightly change, the same signal can always be reproduced with high accuracy from the same target surface as long as the fullerene 7 has the same structure.

The present invention is not limited to the above embodiments, but includes various modifications and design changes within the technical scope of the present invention without departing from the technical concept of the present invention.

[0057]

According to the first aspect of the present invention, a nanotube having a novel structure can be provided, and a nanotube sensitive to various material surfaces can be provided. According to the second aspect of the present invention, the ultrafine particles having a specific structure can be used as the sensor section, and a nanotube that can highly accurately respond to the material surface regardless of the difference in the nanotube can be provided. According to the invention of claim 3,
A nanotube that responds to the magnetic structure of the target substance can be provided, and a nanotube that can be magnetically written on the target substance can be provided. According to the invention of claim 4, a fullerene having a specific structure can be used as a sensor portion, and a nanotube which is highly sensitive to the material surface can be provided irrespective of the difference of the nanotube. According to the fifth aspect of the invention, carbon nanotubes formed with metal ultrafine particles at their tips can be mass-produced at low cost. According to the sixth and seventh aspects of the present invention, nanotubes having a fullerene at the tip can be mass-produced at low cost.

According to the invention of claim 8, since the sensor section is fixed to the tip of the nanotube, it is possible to provide a nanotube probe capable of inputting / outputting and operating surface information of a substance with high accuracy irrespective of the difference between nanotubes. Claim 9
According to the invention, since the sensor section is made of ultrafine particles, it is possible to provide a nanotube probe that can read and write surface information of a target substance using ultrafine particles having the same structure. According to the tenth aspect of the present invention, it is possible to provide a nanotube probe capable of reading surface magnetic information of a target substance and writing magnetic information by using ferromagnetic metal ultrafine particles.

According to the eleventh aspect of the present invention, a high-resolution nanotube probe can be provided at a low cost and in a large amount by utilizing a large amount of fullerenes. According to the twelfth aspect of the present invention, it is possible to provide a manufacturing method capable of mass-producing a nanotube probe using ultrafine particles as a sensor part at low cost and in large quantities. According to the thirteenth aspect, it is possible to provide a manufacturing method capable of mass-producing nanotube probes using fullerene as a sensor part at low cost and in large quantities.

[Brief description of the drawings]

FIGS. 1A to 1D are process diagrams of a method for forming a carbon nanotube with ultrafine particles.

FIG. 2 is a sectional view of a carbon nanotube with ultrafine particles.

FIG. 3 is a process diagram of transferring carbon nanotubes with ultrafine particles to a pyramid of an AFM cantilever which is a kind of a holder.

FIG. 4 is a process diagram for firmly fixing the carbon nanotubes with ultrafine particles to a pyramid.

FIG. 5 is a diagram showing a process of magnetizing Ni ultrafine particles.

FIG. 6 is a use state diagram of a nanotube probe for high-resolution magnetic detection.

FIG. 7 is a magnetic image of a magnetic recording medium displayed on a computer.

FIG. 8 is a process diagram of heat-sealing and fixing the nanotube to the holder by electric current.

FIG. 9 is a process chart showing a fixing method using a coating film.

FIG. 10 is a configuration diagram in which the nanotube probe according to the present invention is applied to an atomic force microscope (AFM).

FIG. 11 is a configuration diagram in which the nanotube probe according to the present invention is applied to a scanning tunneling microscope (STM).

FIG. 12 is an enlarged view of a fullerene C60.

FIGS. 13A and 13B are manufacturing process diagrams of a nanotube probe using fullerene as a sensor unit.

FIG. 14 is a configuration diagram of a fullerene-attached nanotube according to another manufacturing method.

FIG. 15 is a conceptual view of a conventional silicon AFM cantilever.

FIG. 16 is an explanatory view of a magnetic probe considered conventionally.

FIG. 17 is an explanatory diagram in a case where magnetic information of a target substance is detected by the conventional magnetic probe.

[Explanation of symbols]

2 is a silicon substrate having an oxide film on the surface, 4 is a metal film, 6
Is ultrafine particles, 7 is fullerene, 8 is a nanotube or a carbon nanotube, 8a is a base end, 8b is a fused portion, 8
c is a cut surface, 10 is a carbon nanotube with ultrafine particles, 11 is a nanotube with fullerene, 12 is AFM
For cantilever, 14 for pyramid, 15 for holder,
16 is a nanotube probe, 17 is a holder set portion, 17a is a kerf, 18 is a magnetic recording medium, 20 is magnetic information, 22 is a power supply, 24 is a coating film, 28 is a scan driver, 28x is X piezo, and 28y is Y Piezo, 28z
Is a Z piezo, 30 is a semiconductor laser device, 32 is a reflection mirror, 33 is a split photodetector, 34 is an XYZ scanning circuit,
35 is an AFM display device, 36 is a Z-axis detection circuit, 37 is a bias power supply, 38 is a tunnel current detection circuit, 39 is a Z-axis control circuit, 40 is an STM display device, 41 is an XY scanning circuit, 50 is a cantilever, and 52 is a cantilever. Substrate, 54
Is a pyramid-shaped probe, 56 is a sharp point, 58 is a metal film, 6
0 is a magnetic domain, 62 is a target substance, and LB is a laser beam.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) G12B 1/00 601 G12B 1/00 601A (72) Inventor Seiji Akita 1248 Ikeda-cho, Izumi-shi, Izumi-shi, Osaka 4 (72) Inventor Akio Harada 2-7-19-1 Nishi Nishi, Joto-ku, Osaka City, Osaka Prefecture F-term in Daiken Kagaku Kogyo Co., Ltd. 2F069 AA60 AA66 CC05 CC06 DD26 GG62 JJ08 LL02 LL04 5D093 AA10 AC20

Claims (13)

[Claims] 1. A nanotube comprising a sensor portion provided at the tip of the nanotube. 2. The nanotube according to claim 1, wherein the sensor unit is an ultrafine particle. 3. The nanotube according to claim 2, wherein the ultrafine particles are ferromagnetic metal ultrafine particles. 4. The nanotube according to claim 1, wherein the sensor unit is fullerene. 5. A metal thin film is formed on a substrate, the metal thin film is heated to be converted into ultrafine metal particles, and the carbon compound is decomposed by heating while flowing a carbon compound gas over the ultrafine metal particles. A method for producing a nanotube, wherein a carbon component forms a carbon nanotube at its root while pushing up fine particles. 6. A method for producing a nanotube, comprising cutting a required portion of the nanotube and bonding fullerene to the cut surface. 7. A method for producing a nanotube, wherein fullerene is bonded to a closed or open end surface of the nanotube. 8. A nanotube probe, wherein a base end of a nanotube provided with a sensor section at a tip is fixed to a holder. 9. The nanotube probe according to claim 8, wherein the sensor section is an ultrafine particle. 10. The nanotube probe according to claim 9, wherein the ultrafine particles are ferromagnetic metal ultrafine particles. 11. The nanotube probe according to claim 8, wherein the sensor unit is a fullerene. 12. A method of manufacturing a nanotube probe, comprising fixing a base end of the nanotube formed according to claim 5 to a holder. 13. A method for producing a nanotube probe, comprising fixing a base end of the nanotube formed according to claim 6 to a holder.