JP3766682B2 - Nanotube probe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nanotube probe for manipulating a surface signal of a substance 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 capable of manipulating a surface signal of a substance with high reproducibility and high resolution by a sensor unit having a predetermined structure.
[0002]
[Prior art]
Conventionally, there has been an electron microscope as a microscope for observing the surface of a sample at a high magnification. However, since the electron beam does not fly unless it is in a vacuum, there are various problems in the experimental technique. However, in recent years, a scanning probe microscope technique that can observe the surface at an atomic level even in the atmosphere has been developed. When the probe at the tip of the probe is brought 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 detected while scanning the probe on the surface. It is the microscope which makes the sample surface image appear from.
[0003]
Among these microscopes, a scanning tunnel microscope (abbreviated as STM) and an atomic force microscope (abbreviated as AFM) are particularly frequently used. In STM, a conductive probe such as a polished metal needle is used. In AFM, a surface signal is detected using a cantilever having a silicon pyramid as a probe. A problem common to them is that the fine structure at the atomic level of the material surface cannot be detected with high resolution because the tip of the probe cannot be sharpened.
[0004]
For example, FIG. 15 shows a conventional silicon AFM cantilever. The back of the cantilever 50 is fixed to a substrate 52, and a pyramidal probe 54 is formed in front. An extremely fine sharpened portion 56 is formed at the tip of the pyramidal probe 54, and the sharpened portion 56 comes close to the material surface and detects surface information. This AFM cantilever is manufactured by semiconductor planar technology, but no matter how sharp the sharp part is formed, it is considerably larger than the atomic size. Therefore, when the surface information changes depending on the atom size, there is a limit in detecting the surface information to the atomic level with high accuracy even if the probe is used.
[0005]
In recent years, an idea to use carbon nanotubes as a probe has appeared. Since carbon nanotubes are conductive, they can be used not only for STM for detecting tunneling current but also for AFM for detecting atomic force. J. et al. Am. Chem. Soc. 120 (1998), page 603, a carbon nanotube probe has been proposed 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 yet been solved.
[0006]
Although the field is different from the probe microscope field, in recent years, as the memory capacity of a computer increases, the memory device is evolving from a floppy disk device to a hard disk device and further to a high-density disk device. If information is packed in a small space at a higher density, the size per one information becomes smaller, and thus a finer probe for input / output is required. In the conventional magnetic head device, it was impossible to make it smaller than a certain value. There has also been a demand for miniaturization of input / output probes for electronic devices such as CD devices.
[0007]
As an alternative to this magnetic head, the magnetic probe shown in FIG. 16 has been considered. This magnetic probe is configured by forming a ferromagnetic metal film 58 on the sharpened portion 56 of the pyramidal probe 54 by vapor deposition. However, since the ferromagnetic metal film 58 is a polycrystalline film, it has a film structure in which a large number of magnetic domains 60 are arranged in a composite manner.
[0008]
FIG. 17 is an explanatory diagram when the magnetic information of the target substance is detected by this 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 is 1 / z. ² Magnetic information is detected with an intensity proportional to. As a result, these combined signals become magnetic surface information, and it is extremely difficult to detect magnetic information with high resolution. The problem is that the tip itself is quite large at the atomic level and is composed of many magnetic domains.
[0009]
Therefore, it is naturally considered to use the above-described carbon nanotube as the magnetic probe. However, the technology of how to support the ferromagnetic material on the carbon nanotube has not yet been established. Furthermore, the carbon nanotube refining technology and the immobilization technology to the holder are completely unsolved as described above.
[0010]
The inventors have filed three patent applications that provide solutions to the miniaturization technology among these problems. That is, Japanese Patent Application No. 10-280431 provides a method for purifying nanotubes by electrophoresis, Japanese Patent Application No. 10-376642 proposes a technique for immobilizing nanotubes with a coating film, and Japanese Patent Application No. 10-378548 is a thermal process. We have completed the technology for fixing nanotubes by fusion.
[0011]
[Problems to be solved by the invention]
While the present inventors are further researching the nanotube probe, when the nanotube is applied to an STM, AFM, magnetic probe, etc. using the nanotube as a probe, the signal obtained for the same material surface varies depending on the nanotube used. I noticed there was a flaw. This means that the physical structure or electronic structure of the tip of the nanotube that senses the surface signal is different for each nanotube. In other words, the sizes of the nanotubes used are different. Nanotubes are selected and fixed to the holder in the electron microscope, but it is difficult to determine whether the nanotubes have the same structure including size and electronic structure from the electron microscope image.
[0012]
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.
The second object of the present invention is to provide a nanotube probe capable of reproducing the surface information of the target substance with high accuracy by fixing the nanotubes having the same tip part to a holder.
[0013]
[Means for Solving the Problems]
The present invention has been made to achieve the above objects and objects.
The invention of 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 unit is a nanoparticle nanotube.
According to a third aspect of the present invention, the ultrafine particles are ferromagnetic metal nanoparticle nanotubes.
According to a fourth aspect of the present invention, the sensor unit is a fullerene nanotube.
[0014]
In the invention of claim 5, a metal thin film is formed on a substrate, the metal thin film is heated to form ultrafine metal particles, and the carbon compound gas is decomposed by heating while flowing a carbon compound gas over the ultrafine metal particles. The method for producing a nanotube is characterized in that a carbon component forms a carbon nanotube at its root while pushing up ultrafine particles.
The invention according to claim 6 is a method for producing a nanotube, characterized in that a required portion of the nanotube is cut and fullerene is bonded to the cut surface.
The invention according to claim 7 is a method for producing a nanotube in which fullerene is bonded to the closed or opened end face of the nanotube.
[0015]
The invention according to claim 8 is a nanotube probe characterized in that a base end portion of a nanotube provided with a sensor portion at the tip is fixed to a holder.
According to a ninth aspect of the present invention, the sensor unit is an ultrafine particle nanotube probe.
The invention of claim 10 is a nanotube probe in which the ultrafine particles are ferromagnetic metal ultrafine particles.
In the invention of claim 11, the sensor section is a fullerene nanotube probe.
According to a twelfth aspect of the present invention, there is provided a method for producing a nanotube probe, wherein the base end portion of the nanotube formed according to the fifth aspect is fixed to a holder.
A thirteenth aspect of the present invention is a method for manufacturing a nanotube probe, characterized in that the base end portion of the nanotube formed according to the sixth or seventh aspect is fixed to a holder.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
As a result of diligent research in order to make the physical structure and electronic structure of the tip of the nanotube probe the same, the inventors have formed a nanotube structure by separately forming a sensor part with a fixed size and structure at the tip of the nanotube. As a result, we have completed a technology that can guarantee the identity of the sensor unit even if it fluctuates slightly. As long as the sensor parts are 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.
[0017]
The present inventors have reached the recognition that ultrafine particles or fullerene, which is a soccer ball-like substance, is suitable as a sensor unit having a predetermined size and material structure.
[0018]
An ultrafine particle refers to a cluster-like atomic group having a particle size of several tens of nm 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, depending on the production method and production conditions, ultrafine particles having various particle sizes can be produced in a single crystal form or a polycrystalline form having a strong single crystallinity. Therefore, if the production method and conditions are specified, ultrafine particles having a specific particle diameter having the same electronic structure and a single domain can be produced. 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. .
[0019]
The ultrafine particle nanotube probe can be used as a probe probe for a conventional probe microscope such as a scanning tunnel microscope, an atomic force microscope, a friction force microscope, a magnetic force microscope, or a chemical force microscope. If the ultrafine particles for detecting a specific physical and chemical action are fixed to the tip of the nanotube according to each application, the physical and chemical surface information of the target substance can be obtained.
[0020]
For example, if ferromagnetic metal ultrafine particles such as Fe, Co, and Ni are used as ultrafine particles, the magnetic surface structure can be read because the magnetism on the surface of the target substance is sensed. On the other hand, if this ferromagnetic metal ultrafine particle is used as a magnetic head, magnetic information can be written on the surface of the target material, and an input / output probe can be obtained. The unit size of 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 further to 1 nm or less, and it is possible to achieve ultrahigh density.
In this way, the ultrafine particles are extremely small and are effective in measuring the magnetic properties of a minute object. For example, for measuring magnetic properties in living cells, Fe ₂ O ₃ Or Fe ₂ O ₄ The ultrafine particles of iron oxide can be used, and the measurement position in the cell can be finely adjusted freely by using a nanotube probe.
[0021]
If ultrafine particles having a catalytic action are used as the sensor part, 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. Rather than simply disperse and arrange these ultrafine particles as powder, the catalyst arrangement can be adjusted accurately and the catalyst efficiency can be enhanced by fixing to the nanotubes. It can also be used as a probe for catalytic reaction measurement.
[0022]
There are currently two methods for fixing ultrafine particles to the tips of nanotubes. The first is a method in which nanotubes and ultrafine particles are produced separately, and the ultrafine particles are brought very close to the front end surface of the nanotube or a cut surface obtained by cutting the front end and bonded by atomic force. Alternatively, there is a method in which a double bond between the tip surface and the cut surface of the nanotube is opened by light irradiation, a chemical reaction, etc., and ultrafine particles are chemically bonded to the bond. The bonding can be strengthened by fusing by irradiating the bonding portion with an electron beam or laser beam. These series of operations can be performed while directly observing in an electron microscope.
The second is a method of crystal growth of nanotubes and ultrafine particles 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 circulated in the vicinity of the surface, carbon molecules grow at the root of the ultrafine particles by thermal decomposition and grow as carbon nanotubes. It will carry fine particles.
[0023]
Fullerene can be used as the sensor unit. Fullerene is a generic name for soccer ball-like materials, ie, spherical shell molecules. In 1985, the first C in the steam-cooled material obtained by irradiating graphite with a high-energy laser. ₆₀ Was discovered. At present, higher fullerenes having 70 to 100 atoms and larger fullerenes having more than 70 atoms have been discovered, and their synthesis methods have also been established. These fullerenes are carbon sp ² It is composed of a five-membered ring and a six-membered ring created by orbits, and some of them contain seven-membered rings.
[0024]
When fullerene is theoretically considered as a figure, Euler's polyhedral theorem shows that 12 five-membered rings are included and the six-membered ring varies with the number of all atoms. Moreover, it is thought that the isolated five-membered ring rule that 12 five-membered rings are not adjacent is satisfied mathematically. Considering these mathematical rules, the higher fullerenes have C ₇₀ , C ₇₆ , C ₇₈ Etc., and the giant fullerene is C ₂₄₀ , C ₅₄₀ , C ₉₆₀ Etc. exist. Their existence has also been confirmed experimentally.
[0025]
It has been confirmed that fullerenes are contained in large amounts in carbon soot. Accordingly, the method for producing fullerene having a specific structure comprises a method for producing soot and a method for separating specific fullerene from soot. The fullerene soot production method 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 arc discharge, fullerenes having various carbon numbers are mixed in the generated soot. The soot is then separated by chromatographic techniques. In particular, fullerene having a specific number of carbon atoms can be easily separated by using liquid chromatography or column chromatography.
[0026]
For example, by performing high performance liquid chromatography using a polystyrene column and developing solution as benzene or carbon disulfide, C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ , C ₉₀ , C ₉₆ And fullerenes can be separated. It can be considered that fullerenes having a predetermined number of atoms have the same electronic structure except for isomers. Recently, it has also become possible to separate fullerenes of the same size into structural isomers. If it goes to this stage, the fullerene of the specific structure with the same electronic state can be manufactured in large quantities. By fixing the fullerene of this size and structure to the tip of the nanotube, the surface structure of the target substance can be read with high accuracy and reproducibility regardless of the difference in the nanotube, and information can be written on the target surface. become.
[0027]
A fullerene containing a metal can also be produced. For example, graphite powder and metal oxide are mixed at an appropriate ratio, and graphite cement is added to this mixture to form a rod-shaped electrode. When this rod-shaped electrode is slowly heated in an argon atmosphere and finally heated at 1200 ° C. for about 10 hours, the electrode is completed. Using this electrode, arc discharge is performed, and the obtained soot is extracted with a solvent to separate fullerene having a specific structure. A metal atom is confined in the fullerene. Examples of the metal atom include La, Y, and Sc. By changing the metal oxide, a desired metal atom can be included in the fullerene.
[0028]
There are the following methods for fixing the fullerene having the specific structure to the nanotube. First, nanotubes and fullerenes are produced separately. Next, the tip of the nanotube is cut, and fullerene is brought close to the cut surface and bonded by atomic force. The coupling can be strengthened by irradiating the coupling portion with an electron beam or a laser beam. These series of operations are performed while actually observing in an electron microscope.
[0029]
The completed nanotubes can reproduce the same signal with high accuracy from the same target surface because the sensor part that observes the material surface is a fullerene with a specific structure even if the nanotubes have some size variation. it can. Therefore, it is possible to provide a nanotube probe that can measure and manipulate a material surface with high accuracy without being affected by variations in the structure of the nanotube.
[0030]
The fullerene nanotube probe can be used as a probe probe for a conventional probe microscope such as a scanning tunnel microscope, an atomic force microscope, a friction force microscope, a magnetic force microscope, or a chemical force microscope. If a fullerene for detecting a specific physical / chemical action is fixed to the tip of the nanotube according to each application, physical / chemical surface information of the target substance can be obtained.
[0031]
Further, if atoms for detecting specific physical / chemical information are included in fullerene, and the atomic-encapsulated fullerene is fixed to the nanotube, the specific information on the target surface can be detected. For example, when a ferromagnetic metal atom such as Fe, Co, or Ni is included, the magnetic structure of 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.
[0032]
The nanotubes used in the present invention are nanotubes such as carbon nanotubes, BCN-based nanotubes, and BN-based nanotubes. 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 cylindrical carbon nanotubes was recognized in the cathode deposit produced by DC arc discharge.
[0033]
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 bar is packed in a graphite bar and evaporated in helium gas. In addition, BC ₄ Arc discharge is performed in helium gas using N as an anode and graphite as a cathode. By these methods, a BCN-based nanotube in which C atoms in the carbon nanotube are partially substituted with B atoms and N atoms is synthesized, or a multi-layer nanotube in which the BN layer and the C layer are concentrically laminated is synthesized.
[0034]
Very 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 Place the powder in a crucible and heat in nitrogen gas. As a result, most of the C atoms in the carbon nanotube can be converted into a BN nanotube in which B atoms and N atoms are substituted. Of course, various other nanotubes can be used.
[0035]
There are two methods for producing the nanotube probes of the present invention. The first method is to fix the sensor part to the nanotube, and then fix the base end part of the nanotube with the sensor part to the holder. The second method is to fix the base end of the nanotube to the holder first, and then fix the sensor to the tip of the nanotube.
[0036]
In order to fix the nanotube to the sensor unit, the sensor unit may be fixed to the tip of the arranged nanotube (or crystal growth), or the nanotube may be fixed to the arranged sensor unit (or crystal grown). In particular, the latter includes the case of forming the nanotubes while forming the ultrafine particles and pushing up the ultrafine particles.
[0037]
There are two methods for fixing the base end of the nanotube to the holder. The first is a method in which the nanotube is transferred onto the holder surface by applying an electric field or van der Waals force, and the base end portion contacting the holder surface is covered and fixed with a coating film in a state where the tip end portion of the nanotube is projected. 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 of the nanotube in contact with the holder surface is thermally fused to the holder surface.
[0038]
It is also possible to simultaneously form a sensor-attached nanotube and attach it to a holder. Specifically, a metal film is formed on the surface of the silicon pyramid of the cantilever, and further heated to form the metal film into ultrafine metal particles, and then carbon nanotubes are formed to push up the ultrafine metal particles by passing a carbon compound gas. To do. In this way, the sensor-equipped nanotubes are formed at once in the cantilever pyramid, and the manufacturing process can be simplified. Of the carbon compounds, hydrocarbons are preferred.
[0039]
【Example】
[Example 1: Formation of nanotube with ultrafine particles]
1A to 1D are process diagrams of a method for forming carbon nanotubes with ultrafine particles, among the nanotubes with ultrafine particles. A Ni metal film 4 having a thickness of 10 nm is formed by vapor deposition on the surface of a silicon substrate 2 having iron oxide as a surface in FIG. 1A (FIG. 1B). This is put into a cylindrical container having a diameter of 28 mm and a length of 50 cm, and the degree of vacuum is maintained at 60 mTorr while flowing He gas at a flow rate of 50 sccm. When heated to 800 ° C. at a temperature increase rate of 120 ° C. per minute and heat-treated 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. The diameter is about 20 nm. Next, while maintaining a vacuum of 60 mTorr without breaking the vacuum, ₆ H ₆ When gas is flowed at a flow rate of 10 sccm for 1 hour, carbon atoms accumulate at the lower end of the Ni ultrafine particles 6 due to the dehydrogenation catalytic reaction of the Ni ultrafine particles 6 to form carbon nanotubes 8. The carbon nanotubes 8 grow while pushing up the Ni ultrafine particles 6 to form carbon nanotubes 10 with ultrafine particles.
[0040]
FIG. 2 is a cross-sectional view of the carbon nanotube 10 with ultrafine particles. The diameter d of the carbon nanotube 8 was distributed in the range of 15 to 150 nm, and the average was 45 nm. The diameter D of the Ni ultrafine particles 6 is slightly larger than the diameter d, but in order to reduce the diameter D, the thickness of the Ni metal film 4 is reduced, the heat treatment time for making ultrafine particles is shortened, etc. There is a way.
[0041]
FIG. 3 is a process diagram for transferring the carbon nanotubes 10 with ultrafine particles to the pyramids 14 of the AFM cantilever 12. In this case, the pyramid 14 becomes a holder for attaching the carbon nanotubes 10 with ultrafine particles. A DC electric field is formed between the silicon substrate 2 on which the carbon nanotubes 10 with ultrafine particles 10 are formed and the cantilever 12 by a DC power source 16, and the carbon nanotubes 10 with ultrafine particles jump to the pyramids 14 by this electrostatic field force. In this case, the ultrafine particles 6 protrude at the tip, the axis of the carbon nanotube 8 is substantially perpendicular to the cantilever 12, and the base end 8 a is adjusted to be joined to the pyramid 14. These operations are performed while directly observing in an electron microscope. The direction of the electrode of the DC power supply 16 is adjusted according to the charging property of the nanotube.
[0042]
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 transformed to become a fused portion 8b and is fixed to the pyramid 14 by thermal fusion.
[0043]
FIG. 5 is a magnetization process diagram of the Ni ultrafine particles 6. In this sample, the nanotube diameter d is 25 nm, the Ni ultrafine particle diameter D is 35 nm, and the tip length L is 400 nm. The Ni ultrafine particles 6 are magnetized by applying a pulse magnetic field B of 12.5 Tesla for 10 ms. The Ni ultrafine particles 6 are single domain ferromagnets, and this pulse magnetization can be used as a nanotube probe 16 for high resolution magnetic detection having a single magnetization domain.
[0044]
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 preferably 50 to 100 nm, but is set to 80 nm in order to avoid the influence of van der Waals force.
[0045]
FIG. 7 is a magnetic image of the magnetic recording medium 18 displayed on the computer. The object to be scanned is an area of 20 μm × 20 μm, and the interval between magnetic tracks is 1.5 μm. Thus, 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 the magnetic recording medium using the nanotube probe 16. When the surface of the magnetic recording medium is scanned while applying a magnetic signal to the Ni ultrafine particles 6 by an electronic device (not shown), magnetic signals are successively written.
[0046]
FIG. 8 is a process diagram showing another method for fixing the nanotube 8 to the holder. In this case, the holder is a pyramid 14, and an electric current is passed between the nanotube 8 and the cantilever 12 via the power source 22, and the proximal end portion 8 a is transformed into the fused portion 8 b to be fixed to the pyramid.
[0047]
FIG. 9 is a process diagram 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 the coating film 24 which is a carbon film is deposited on the base end portion 8 a of the nanotube 8. The carbon nanotube 8 is firmly fixed to the pyramid 14 by the coating film 24. In addition to the above method, various known methods such as physical vapor deposition and chemical vapor deposition (CVD) can be used as the method for forming the coating film 24. In this coating film method, since a coating film can be formed also on the tip part of the carbon nanotube 8, resonance can be suppressed by increasing the thickness of the carbon nanotube 8, and an effect of improving accuracy can be obtained.
[0048]
FIG. 10 shows an atomic force microscope (AFM) for the nanotube probe 16 according to the present invention.
It is the block diagram applied to. Ultrafine particles at the tip of the nanotube probe 16 come into contact with the sample surface, and the sample surface information can be read accurately. The nanotube probe 16 is detachably fixed to a holder set portion (not shown). When the probe is replaced, the entire probe 16 is replaced. In this case, the probe is a nanotube with a sensor portion. The sample 26 is driven in the X, Y, and Z directions by a scan driving unit 28 made of a piezo element. Reference numeral 30 denotes a semiconductor laser device, 32 denotes a reflection mirror, 33 denotes a two-divided photodetector, 34 denotes an XYZ scanning circuit, 35 denotes an AFM display device, and 36 denotes a Z-axis detection circuit.
[0049]
The sample 26 is moved in the Z-axis direction until it reaches a predetermined repulsive position with respect to the nanotube probe 16, and then the scanning drive unit 28 is scanned in the XY directions by the scanning circuit 34 with the Z position fixed. At this time, the cantilever 12 is bent by the unevenness of the surface atoms, and the reflected laser beam LB is incident on the two-divided photodetector 33 while being displaced. A displacement amount in the Z-axis direction is calculated by the Z-axis detection circuit 36 based on the difference between the light detection amounts of the upper and lower detectors 33a and 33b, and a surface atomic image is displayed on the AFM display device 35 with this displacement amount as an atomic unevenness amount. . In this apparatus, the sample 26 is configured to perform XYZ scanning, but the probe 16 may be subjected to XYZ scanning.
[0050]
FIG. 11 is a configuration diagram of a scanning tunneling microscope (STM) to which the nanotube probe according to the present invention is applied. A nanotube probe 16 is formed by fixing the nanotube 10 with ultrafine particles to a flat holder 15 as a probe. The fixing method may be a fusion method, a coating film method, or other methods. The holder 15 is fitted into the kerf 17a of the holder setting portion 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 realizes scanning of the sample 26 of the nanotube probe 16 by extending and contracting the holder set unit 17 in the three-dimensional direction of XYZ. 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.
[0051]
The Z-axis control circuit controls the expansion and contraction of the nanotube probe 16 in the Z direction so that the tunnel current is constant at each XY position, and this movement amount becomes the unevenness amount in the Z-axis direction. As the nanotube probe 16 is XY-scanned, the 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 setting portion 17 and is exchanged as a probe 16 integrally.
[0052]
FIG. 12 shows C ₆₀ It is an enlarged view of fullerene. This fullerene is composed of 12 pentagons and 20 hexagons, and the isolated five-membered ring rule is established that the pentagons are not adjacent to each other. 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 with high resolution can be formed.
[0053]
FIGS. 13A to 13B are manufacturing process diagrams of a nanotube probe using fullerene as a sensor part. The nanotube 8 in the step (A) may be any nanotube such as a CNT-based nanotube, a BCN-based nanotube, or a BN-based nanotube. In the step (B), the required portion of the nanotube 8, mainly the tip portion, is cut. In the step (C), the fullerene 7 is bonded to the cut surface 8c by van der Waals force to form the fullerene-attached nanotube 11. In order to strengthen this adhesion, both can be fused at the joint by electron beam irradiation or current heating.
[0054]
FIG. 14 shows another method for forming fullerene-attached nanotubes. The tip of the nanotube 8 is normally closed, and the double bond is opened at the closed tip surface using photoexcitation or a catalyst. Similarly, fullerene double bonds are also opened, and fullerene-attached nanotubes 11 can be formed by combining the bonds of both bonds. This method can also be applied to nanotubes with open ends. Here, the term “opened” includes both the case of opening by cutting and the case of opening in a natural state.
[0055]
A nanotube probe can be constructed by fixing the base end of the fullerene-attached nanotube 11 to a holder (not shown). As the fixing method, the above-described coating film method or fusion method can be used. In this way, even if the thickness and structure of the nanotube 8 are slightly changed, the same signal can always be accurately reproduced from the same target surface as long as the fullerene 7 has the same structure.
[0056]
The present invention is not limited to the above embodiments, and includes various modifications, design changes, and the like within the technical scope without departing from the technical idea of the present invention.
[0057]
【The invention's effect】
According to the first aspect of the present invention, a nanotube having a novel structure can be provided, and a nanotube sensitive to the surface of various substances can be provided.
According to the invention of claim 2, ultrafine particles having a specific structure can be used as a sensor part, and a nanotube sensitive to the surface of a substance can be provided with high accuracy regardless of the difference between the nanotubes.
According to the invention of claim 3, it is possible to provide a nanotube that is sensitive to the magnetic structure of the target substance, and to provide a nanotube that can be magnetically written to the target substance.
According to the invention of claim 4, fullerene having a specific structure can be used as a sensor part, and a nanotube sensitive to the surface of a substance can be provided with high accuracy regardless of the difference in nanotube.
According to the invention of claim 5, it is possible to mass-produce carbon nanotubes formed with metal ultrafine particles at the tip at low cost.
According to the inventions of claims 6 and 7, it is possible to mass-produce nanotubes having fullerene formed at the tip at low cost.
[0058]
According to the invention of claim 8, since the sensor part is fixed to the tip of the nanotube, it is possible to provide a nanotube probe capable of inputting / outputting and manipulating the surface information of a substance with high accuracy regardless of the difference between the nanotubes.
According to the ninth aspect of the present invention, since the sensor portion is an ultrafine particle, 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 invention of claim 10, by using the ferromagnetic metal ultrafine particles, it is possible to provide a nanotube probe capable of reading the surface magnetic information of the target substance and writing the magnetic information.
[0059]
According to the invention of claim 11, it is possible to provide a high-resolution nanotube probe in a large amount at a low cost by utilizing a large amount of fullerene.
According to the twelfth aspect of the present invention, it is possible to provide a manufacturing method capable of mass-producing nanotube probes having ultrafine particles as sensor portions at low cost.
According to the invention of claim 13, it is possible to provide a manufacturing method capable of mass-producing a nanotube probe using fullerene as a sensor part at a low cost.
[Brief description of the drawings]
FIG. 1A to FIG. 1D are process diagrams of a method for forming carbon nanotubes with ultrafine particles.
FIG. 2 is a cross-sectional view of a carbon nanotube with ultrafine particles.
FIG. 3 is a process diagram for transferring carbon nanotubes with ultrafine particles to a pyramid of an AFM cantilever which is a kind of holder.
FIG. 4 is a process diagram for firmly fixing a carbon nanotube with ultrafine particles to a pyramid.
FIG. 5 is a magnetization process diagram of 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 for fixing a nanotube to a holder by heat fusion with an electric current.
FIG. 9 is a process diagram showing a fixing method using a coating film.
FIG. 10 is a configuration diagram in which a 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 C60 fullerene.
FIGS. 13A to 13B are manufacturing process diagrams of a nanotube probe using fullerene as a sensor part.
FIG. 14 is a configuration diagram of fullerene-attached nanotubes produced by another manufacturing method.
FIG. 15 is a conceptual diagram of a conventional silicon AFM cantilever.
FIG. 16 is an explanatory diagram of a conventionally considered magnetic probe.
FIG. 17 is an explanatory diagram when magnetic information of a target substance is detected by this 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 carbon nanotube, 8 a is a base end, 8 b 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 a cantilever for AFM, 14 is a pyramid, 15 is a holder, 16 is a nanotube probe, 17 is a holder set portion, 17 a is a groove, 18 is a magnetic recording medium, 20 Is a magnetic information, 22 is a power supply, 24 is a coating film, 28 is a scanning drive unit, 28x is an X piezo, 28y is a Y piezo, 28z is a Z piezo, 30 is a semiconductor laser device, 32 is a reflection mirror, and 33 is a split light. Detector, 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, and 38 is a top Channel 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, 52 is a substrate, 54 is a pyramidal probe, 56 is a sharpened portion, 58 is a metal film, Reference numeral 60 denotes a magnetic domain, 62 denotes a target substance, and LB denotes a laser beam.

Claims (5)

A probe to be assembled while observing directly in electron microscopes, electron and the nanotube, and a holder for holding the nanotube, the required area of the proximal end of the proximal end portion of the nanotube is attached to the surface of the holder A coating film for fixing the nanotube to the holder by coating with a carbon material generated by electron beam irradiation in a microscope, and a probe for scanning the sample surface over the tip of the nanotube arranged so as to protrude from the holder. A sensor substance is bonded and fixed to the tip of the nanotube, or a cut surface obtained by cutting the tip, and the sensor substance is used as a probe point for directly scanning the sample surface, and the size and structure of the sensor substance are adjusted. A nanotube probe characterized by improving the reproduction accuracy of the sample surface image . A probe assembled while directly observing in an electron microscope, a nanotube, a holder for holding the nanotube, and a base end portion of the nanotube attached to the surface of the holder so that the base end portion itself in the electron microscope And a cutting surface obtained by cutting the tip of the nanotube or the tip of the nanotube, using the fusion part fused to the holder and the tip of the nanotube arranged so as to protrude from the holder as a probe for scanning the sample surface The nanotube is characterized in that the sensor substance is bonded and fixed to the probe, and the sensor substance is used as a probe point for directly scanning the sample surface, and the size and structure of the sensor substance are adjusted to improve the reproduction accuracy of the sample surface image. probe. 3. The nanotube probe according to claim 1, wherein the sensor substance is fused to a distal end of the nanotube or a cut surface obtained by cutting the distal end to enhance bonding . 4. The nanotube probe according to claim 1, wherein the sensor substance is ultrafine particles or fullerene . 5. The nanotube according to claim 4, wherein the ultrafine particles are ferromagnetic metal ultrafine particles, a single magnetization domain is formed by magnetizing the ferromagnetic metal ultrafine particles, and the sample surface can be magnetically detected by the single magnetization domain. probe.

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