JP3557589B2 - Method of manufacturing probe for scanning probe microscope, probe manufactured by the method, and manufacturing apparatus - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a probe for a scanning probe microscope in which carbon nanotubes are attached to the tip of a probe, a probe manufactured by the manufacturing method, and an apparatus for manufacturing the same.
[0002]
[Prior art]
As is well known, scanning probe microscopes have a fundamental principle of detecting physical and chemical information such as surface irregularities and conductivity by tracing a solid surface with a sharp tip. The shape and stability of the probe greatly affect the resolution as a microscope. This conventional probe is manufactured by mechanically polishing a metal wire such as tungsten or platinum iridium, or by chemical etching in a solution. However , in each case, accurate measurement of physical properties is difficult because the shape of the tip cannot be accurately grasped. Specifically, the derivation of important physical properties becomes difficult with different materials greatly lowered resolution by adsorbs, shape and elemental composition unknown because, for example, an atomic force microscope and the probe material to the tip . Also, measurement of deep holes and the like on the surface of a substance is impossible with a conventional probe, and a probe with a higher aspect ratio has been required.
[0003]
Despite these problems, it has been put into practical use in view of its usefulness. However, in recent years , the application of each technique of carbon nanotubes (CNT) has been studied, and it has been adopted as a probe. Has reached. As is generally known, the carbon nanotube is a substance composed of cylindrical carbon atoms, and has a diameter (selectable in a range of 1.5 nm to 20 nm) and a length (a range of several nm to 500 nm to several μm). in a ratio to be able to take up 1000 times more selectable), flexible and rigid (50GP a) has a high property. In addition, carbon nanotubes include multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (single wall carbon nanotubes), and the electrical properties of the carbon nanotubes are such that they can be made into metals and semiconductors due to their various spiral structures. It is known to have It is also known that they have high rigidity, elasticity, toughness and excellent mechanical properties. Furthermore, it has low reactivity, high stability and excellent chemical properties. Such an electronically and mechanically rare property has attracted attention and has been put to practical use as a probe for a scanning probe microscope. That is, by attaching the carbon nanotubes to the tip of the probe, the mechanical wire of the metal wire described above, precise high-resolution shape observation and physical property measurement that could not be done by the probe obtained by the production by a chemical method, It is possible to measure deep holes on the surface of a substance and obtain highly reliable data.The size of the tip can be made uniform by purifying and using the carbon nanotubes of the material.Since the atom at the tip is single carbon The electrical characteristics are constant, the reactivity is low compared to metal probes, so the adhesion of impurities is extremely small and stable.The mechanical strength is high and the life is long without any change due to collision with the sample surface. Thus, various advantages such as the length of the carbon nanotubes can be selected according to the application are obtained.
[0004]
For this reason, several methods for forming carbon nanotubes at the tip of a probe have been proposed. One of the methods is to attach the probe directly to the tip of the probe using an adhesive under an optical microscope, or to attach a hydrocarbon in the atmosphere as a raw material under an electron microscope in place of the adhesive. is there. There is also a method in which carbon nanotubes are grown directly on the tip of a probe by a CVD method (chemical vapor deposition, abbreviation for chemical vapor deposition).
[0005]
[Problems to be solved by the invention]
However, the method of manufacturing by attaching carbon nanotubes using an adhesive substance and a hydrocarbon as raw materials has a problem that, in addition to having to manufacture in a vacuum, the manufacturing time is enormous and mass production is not possible. There is. Further, there is a problem that the adhesive substance has a great possibility of adversely affecting the mechanical and electrical properties of the carbon nanotube. Further, in the method of using a CVD method, there is a problem that not suitable for various properties measured with a scanning probe microscope in order number of the carbon nanotubes are formed at a time.
[0006]
[Means for Solving the Problems]
The present invention was made in view of the above circumstances, the invention of claim 1, in a container with a solution obtained by dispersing carbon nanotubes in an organic solvent, consisting of tip sharp metal or semiconductor probe was opposed open a little gap between sharp electrode, by applying a voltage to the electrode and the probe, a scanning probe, characterized in that to produce by attaching the carbon nanotube on the tip of the probe This is a method for manufacturing a microscope probe .
The invention according to claim 3 provides a container for containing a solution in which carbon nanotubes are dispersed in an organic solvent, a probe and a sharp electrode made of a metal or semiconductor having a sharp tip and opposed to the container at a small interval. And a power supply for applying a voltage to the probe and the electrode, so that the carbon nanotubes can be attached to the tip of the probe. .
In the inventions of claims 2 and 4, the tip of the probe has a plurality of carbon nanotubes .
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
About the embodiment of the present invention will be described with reference to FIGS. 1 and 2, but first, preparing apparatus will be described for use in the method for manufacturing a scanning probe microscope tip.
The manufacturing apparatus 1 includes: a container 3 containing a solution 2 in which carbon nanotubes are dispersed; an electrode 4 installed in the container 3; a probe 5 installed in the container 3 so as to face the electrode 4; The probe 5 is electrically connected to the electrode 4 and is provided with a power supply 6 for supplying any voltage of direct current, alternating current, or superimposed alternating current and direct current.
[0008]
Solution 2 in which carbon nanotubes are dispersed is a solution in which carbon nanotubes 7 are dispersed in an organic solvent. As the organic solvent, di-chloroethane, toluene, and carbon tetrachloride. The amount of the carbon nanotubes 7 dispersed in such an organic solvent is not particularly limited, but may be about several percent. As the carbon nanotube 7, one appropriately selected from the range of 1.5 to 20 nm in diameter and several nm to several μm in length according to the purpose of use is used. However, it is not limited to these ranges.
[0009]
The electrode 4 is made of a conductive material and preferably has a sharp tip such as a razor blade, but may have no width such as a needle tip. As shown in the figure, when the electrode 4 is formed on a razor blade and a sharp portion at the tip has a width, a large number of probes 5 can be arranged at one time along the width, so that the electrode 4 can be manufactured. However, the working efficiency is improved, but when one or a small number is manufactured, the width may not be provided as in the case of the needle tip.
[0010]
The tip of the tungsten or platinum iridium wire which has been sharpened in advance by a conventional method can be used as the probe 5. The cantilever for the atomic force microscope may be replaced with a probe made of tungsten or the like. The probe 5 is supported by the support device 8 so that the tip of the probe 5 can keep the distance α from the tip of the electrode 4 to about 1 mm.
[0011]
As the power source 6, a power source that can apply a voltage of several V to several tens V or more between the probe 5 and the electrode 4 using an AC or DC having a high frequency or a power in which an AC and a DC are superimposed is used as the power source 6. select. The type of power source and the magnitude of the voltage can be efficiently attached by appropriately selecting the optimal type and size in consideration of the length and diameter of the carbon nanotubes dispersed in the organic solvent.
[0012]
In the case of manufacturing a probe for a scanning probe microscope using the manufacturing apparatus 1 having the above configuration, when the power supply 6 is connected to the probe 5 and the electrode 4, as shown in the photograph of FIG. The carbon nanotubes 7 dispersed in the organic solvent adhere to the tip of the needle 5. FIG. 4 illustrates the photograph of FIG. 3 for easy understanding. Usually, a plurality of carbon nanotubes 7 are intricately entangled and adhere to the tip of the probe 5, and the tip of the tip is used as the probe. Since a plurality of wires are intricately entangled and formed into a bundle, they have more excellent mechanical characteristics than a case where only one is attached. However, under special conditions, such as when the amount of carbon nanotubes dispersed in the organic solvent is small, or when the voltage is applied for a very short time, one or a very small number may be attached as necessary. It is possible. The thus produced one has an advantage that the raw material cost can be reduced, though the mechanical strength is inferior to that of the one having a plurality of attached.
[0013]
When a large number of probes 5 with carbon nanotubes 7 are manufactured at the same time, the length of the electrode 4 is increased, and a large number of probes 5 are also slightly attached to the support device 8 along the tip of the electrode 4. If they are arranged at a distance from each other and can be attached detachably, they can be easily manufactured.
[0014]
FIG. 5 shows a clean surface image of Si (111) 7 × 7 taken by a scanning tunneling microscope using a probe with a carbon nanotube for a scanning probe microscope manufactured using the manufacturing method and the manufacturing apparatus of the present invention. Show. FIG. 6 is the same clean surface image taken using a conventional metal probe. A comparison between the two shows that a clearer image can be obtained by using the probe with a nanotube of the present invention. Note that the scanning tunnel microscope is one type of the scanning probe microscope, and is included in the range of the scanning probe microscope.
[0015]
【The invention's effect】
As is clear from the above description, according to the method for manufacturing a probe for a scanning probe microscope of the present invention, there is an advantage that a large number of probes with carbon nanotubes can be simultaneously manufactured in only a few seconds. Further, since no adhesive substance is used, there is an advantage that the carbon nanotube can be manufactured without adversely affecting the mechanical and electrical properties of the carbon nanotube. Furthermore, since it is not necessary to manufacture the device in a vacuum, there is an advantage that manufacturing cost and labor can be reduced.
[0016]
In addition, the apparatus for manufacturing a probe for a scanning probe microscope can manufacture a plurality of probes with carbon nanotubes for a scanning probe microscope in a very short time while having a very simple configuration.
[0017]
Further, the probe with a carbon nanotube manufactured by the method and apparatus for manufacturing a probe for a scanning probe microscope has no carbon nanotube attached to the probe using an adhesive substance or hydrocarbon as a raw material. The mechanical and electrical properties are not adversely affected, resulting in longer life, improved resolution, and the ability to measure deep holes in material surfaces.
[0018]
Furthermore, if the carbon nanotubes of the probe with carbon nanotubes produced by this method for producing a probe for a scanning probe microscope are intricately intertwined and adhered, one of the tips protruding toward the tip side is attached. It can be used effectively, and the more attached the root, the more firm it becomes. As a result, the mechanical rigidity of the tip is higher than that of a single probe directly bonded to the probe, and the advantage is that carbon nanotubes are not easily destroyed even when the tip contacts the surface of the object to be measured. is there.
[Brief description of the drawings]
FIG. 1 is an overall explanatory view of a manufacturing apparatus of a probe with a carbon nanotube for a scanning probe microscope. FIG. 2 is an enlarged explanatory view of a probe and an electrode in FIG. 1. FIG. 3 is an enlarged photograph in which a carbon nanotube adheres to the probe. 4 is an explanatory view of FIG. 3; FIG. 5 is a clean surface image of Si (111) 7 × 7 taken with a scanning tunnel microscope using a probe manufactured by the manufacturing method and the manufacturing apparatus of the present invention. A clean surface image of the same Si (111) 7 × 7 photographed by using a conventional metal probe with a scanning tunneling microscope.
REFERENCE SIGNS LIST 1 preparation apparatus 2 solution in which carbon nanotubes are dispersed in organic solvent 3 container 4 electrode 5 probe 6 power supply 7 carbon nanotube

Claims (4)

In the container containing the solution obtained by dispersing carbon nanotubes in an organic solvent, the tip is opposed open a little gap between sharp electrode tip is made of a sharp metal or a semiconductor, the voltage on the electrode and the probe by providing a method of preparing a scanning probe microscope tip, characterized in that to produce by attaching the carbon nanotube on the tip of the probe. The method according to claim 1, wherein a plurality of carbon nanotubes adhere to the tip of the probe. A container containing a solution in which carbon nanotubes are dispersed in an organic solvent, a probe and a sharp electrode made of a metal or semiconductor having a sharp tip and opposed to each other at a small interval in the container, and the probe and the probe An apparatus for manufacturing a probe for a scanning probe microscope, wherein a power supply for applying a voltage to an electrode is provided so that the carbon nanotube can be attached to the tip of the probe. Scanning probe microscope probe of a manufacturing apparatus according to claim 3, wherein the carbon nanotubes adhering to the tip of the probe is a plurality of lines.

Images