Patent Number: 
Section: description

In the following modes of probe for the scanning microscope produced by focused ion beam machining according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing an apparatus by which a probe for a scanning type microscope is manufactured by using a focused ion beam. In the focused ion beam apparatus 2, a cantilever 4 is disposed, and this cantilever 4 comprises a cantilever portion 6 and a protruding portion 8 called a pyramidal portion. The base end portion 16 of the nanotube 12 is adhered on a surface 10 of the protruding portion 8 and a tip end portion 14 is disposed in a protruding fashion on the surface 10. The nanotube 12 may be adhered in the focused ion beam apparatus 2, or may be disposed in the focused ion beam apparatus 2, after being adhered in an electron microscope which is not drawn here. An organic gas G is driven from outside into the focused ion beam apparatus 2, and is caused to flow to the arrow direction a. This organic gas G is absorbed to adhere to near the nanotube 12, and an adhesion matter 18a of the organic gas is formed. The organic gas G is decomposed when a focused ion beam I is irradiated in the arrow direction b against the adhesion matter of the organic gas, so that light molecules D such as a hydrogen component, etc. are scattered in the dotted line direction. On the other hand, decomposed components such as a carbon component and a metallic component, etc. heap up near the base end portion 16 of the nanotube 12 to form a decomposed deposit 18. The cantilever 6 and the probe 12 are combined by this decomposed deposit 18 and the probe for the scanning type microscope 20 (hereafter called probe 20) is accomplished. FIG. 2 is a schematic diagram showing an accomplished probe for the scanning microscope produced by focused ion beam machining. The base end portion 16 of the nanotube 12 is firmly fastened to the surface 10 of a protruding portion by a decomposed deposit 18. The durability of the probe 20 depends on the fastening strength of the decomposed deposit 18 which serves as a coating film. The fastening strength of the decomposed deposit 18 is decided by the denseness of the decomposed deposit 18 and the fitness (combination degree) of the decomposed deposit 18 to the surface 10 of the protruding portion. The decomposed deposit formed carbon film, when gases of hydrocarbon series such as an ethylene, an acetylene, a methane, etc. are used as the organic gas. The carbon film comprises amorphous carbon and is conductive in a case where the film thickness is extremely thin. Accordingly, making the carbon film thin, the nanotube 12 and the cantilever 4 can be set so as to be electrically connected through the carbon film. Furthermore, when an organic-metallic gas is used for the organic gas, a metallic component is produced as a decomposed component in a collision-decomposition reaction of the gas with an ion beam, and the metal heaps up near the nanotube base end portion 16 and forms a metal film which composes the decomposed deposit. In the same manner as the above described carbon film, the nanotube 12 and the cantilever 4 can be set in an electrically connected state through the metal film. As described above, the following gases can be utilized as organic-metallic gases; for examples, W(CO)6, Cu(hfac)2, (hfac: hexa-flouro-acetyl-acetonate), (CH3)2AlH, Al(CH2xe2x80x94CH)(CH3)2, [(CH3)3Al]2, (C2H5)3Al, (CH3)3Al, (Ixe2x80x94C4H9)3Al, (CH3)3AlCH3, Ni(CO)4, Fe(CO)4, Cr[C6H5(CH3)2], Mo(CO)6, Pb(C2H5)4, Pb(C5H7O2)2, (C2H5)3PbOCH2C(CH3)2, (CH3)4Sn, (C2H5)4Sn, Nb(OC2H5)5, Ti(i-OC3H7)4, Zr(C11H19O2)4, La(C11H19O2)3, Sr[Ta(OC2H5)6]2, Sr[Ta(OC2H5)5(Oc2H4OcH3)]2, Ba(C11H19O2)2, (Ba,Sr)3(C11H19O2), Pb(C11H19O2)2, Zr(OtC4H9)4, Zr(OiC3H7)(C11H19O2)3, Ti(OiC3H7)2(C11H19O2), Bi(OtC5H11)3, Ta(OC2H5)5, Ta(OiC3H7)5, Nb(OiC3Hxe2x80x2)5, Ge(OC2H5)4, Y(C11H19O2)3, Ru(C11H19O2)3, Ru(C5H4C2H5)2, Ir(C5H4C2H5)(C8H12), Pt(C5H4C2H5)(CH3)3, Ti[N(CH3)2]4, Ti[N(C2H5)2]4, As(OC2H5)3, B(OC2H3)3, Ca(OCH3)2, Ce(OCxe2x80x3H5)3, Co(OiC3H7)2, Dy(OiC3H7)2, Er(OiC3H7)2, Eu(OiC3H7)2, Fe(OCH3)3, Ga(OCH3)3, Gd(OiC3H7)3, Hf(OCH3)4, In(OCH3)3, KOCH3, LiOCH3, Mg(OCH3)2, Mn(OiC3H7)2, NaOCH3, Nd(OiC3H7)3, Po(OCH3)3, Pr(OiC3H7)3, Sb(OCH3)3, Sc(OiC3H7)3, Si(OC2H5)4, VO(OCH3)3, Yb(OiC3H7)3, Zn(OCH3)2, etc. As to the deposit 18, not only conductive deposits such as the above described carbon film and metal film but also an insulation deposit and a semi-conduction deposit are included. When gases of hydrocarbon series or organic-metallic gases heap up to be in a semi-decomposition state, these tend to form insulation deposits. In a case of a silicon film, according to the crystal type of the film, various deposits are formed, i.e. from a semi-conduction deposit to an insulation deposit. FIG. 3 is a schematic diagram showing a probe for a scanning type microscope using a conductive cantilever. A conductive cantilever is composed by means of forming an electrode film 22 on the cantilever 4. As a nanotube 12, a conductive carbon nanotube is used, then the nanotube 12 and the cantilever 4 are electrically connected each other through a conductive deposit 18, so that a voltage can be applied between a specimen and the nanotube 12 though an external power supply which is not shown in the diagram. Describing it in detail, as the nanotube 12, there are, for examples, a conductive carbon nanotube, an insulation BN series nanotube, a BCN series nanotube, etc. Also, as the cantilever 4, there are a conductive cantilever, a semi-conduction silicon cantilever, an insulation silicon-nitride cantilever, etc. Furthermore, as the deposit 18, there are a conductive deposit, a semi-conduction deposit and an insulation deposit. Though the nanotube 12 seems to contact with a protruding surface 10 of the cantilever, depending on the magnitude of electric contact resistance or due to the existence of interposition, both are not necessarily electrically connected. Then, the electric property of the deposit 18 connecting both is important. Therefore, according to the way of combination of the nanotube 12, the deposit 18 and the cantilever 4, either the electric connection or disconnection between the nanotube 12 and the cantilever 4 is certainly decided. FIG. 4 is a schematic diagram showing the method to remove an unnecessary deposit by using a focused ion beam. Decomposed gases of the organic gas form not only the deposit 18 which fastens a nanotube but also occasionally an unnecessary deposit 24 by adhering to the tip end portion of the nanotube 12. The unnecessary deposit 24 thus produced causes to reduce the imaging power of the nanotube 12. Therefore, the unnecessary deposit 24 is scattered as shown by dotted arrow-lines by irradiating the focused ion beam I in the direction of the arrow c against the unnecessary deposit 24. As the result, only a tip end 14a is remained at the probe needle point of the nanotube 12, so that the imaging power can be recovered. In this manner, the unnecessary deposit on the nanotube 12 or the cantilever 4 can be removed by using the focused ion beam I. FIG. 5 is a schematic diagram showing a method to control nanotube length by using a focused ion beam. The length of nanotube 12 is spreading over from nano-order to micron-order. When the tip end portion of the nanotube 12 is long, the tip end portion oscillates, so that a sharp image of the surface of specimen cannot be obtained. Therefore, in order to unify the operation quality of a probe 20 and to increase its efficiency, it is necessary to uniform the length of the tip end portion 14 of the nanotube. Then, in order to control the length of the tip end portion 14 of the nanotube, the unnecessary portion should be cut off. For the cutting off, solution-cutting force of the focused ion beam is utilized. Since an energy density of the ion beam can be controlled by increasing acceleration energy or by increasing a degree of focusing of the focused ion beam, it is possible to give the energy density enough for solution-cutting off the nanotube to the focused ion beam I. When this focused ion beam is irradiated against a cut region P in the arrow direction d, the cut region P melts and the tip end portion is cut off like a cut peace 14b. Thus, the section turns to a new tip end 14a. In this example, the section is perpendicular against an axis direction of the nanotube 12. FIG. 6 is a schematic diagram showing a method to cut obliquely the nanotube. In this case, the focused ion beam I is irradiated in an oblique direction (arrow direction e) against the nanotube 12. By means of this oblique cut, the tip end 14a of the nanotube comes to be quite sharp, so that this cutting method can provide a probe 20 possessing higher quality than the perpendicular cutting method shown in FIG. 5. The reason is that the more sharp is the tip end 14a, the higher a resolution for a surface image of specimen increases. FIG. 7 is a schematic diagram showing a method to improve the quality of the tip end of the nanotube. By irradiating the focused ion beam I to the tip end region 14c of the tip end portion 14 of the nanotube 12, ions are driven into the tip end region. According as an acceleration voltage applied to the focused ion beam, various cases occur such that an ion film is formed on the surface of the tip end region 14c, the ions replace constituent atoms of the nanotube or fall, as solid solution, into holes of an atomic surface, and or the ions are injected into an inner space of the tip end region 14c.  In a case where, as the sort of the ions, for examples, fluorine, boron, gallium, or phosphorus, etc. are employed, these atoms react on carbon atoms in the nanotube to form CF-combination, CB-combination, CGa-combination or CP-combination, which are caused to possess the specific property corresponding to each combination. In a case where the ions are ferromagnetic atoms such as Fe, Co, Ni, etc., ferromagnetism of the surface of a specimen can be detected at the atomic level. Furthermore, the improvement of qualities of nanotubes includes the case to give conductivity to an insulation BN series nanotube or the BCN series nanotube by shooting metal ions to them and inversely, also the case to give insulation property to a conductive carbon nanotube by shooting insulation substance to the nanotube. It is needless to say that the present invention is not limited to the above-described embodiments; and various modifications and design changes, etc. within this limits that involve no departure from the technical spirit of the present invention are included in the scope of the present invention. According to the present invention, a nanotube and a cantilever are fastened to each other with a deposit which is made of decomposed component produced by decomposing organic gases using a focused in beam so that the fastness is quite firm, therefore, the present invention can provide a probe for a scanning type microscope in which the nanotube does not fall out from the cantilever in many times repeated use. According to the present invention, since a hydrocarbon gas is used as an organic gas, if the decomposed deposit is made extremely thin so as to give the carbon film conductivity, the nanotube and cantilever are set in electrically connected state by means of the conductive carbon film and a voltage can be applied to flow current in the probe for the scanning type microscope. According to the present invention, since a organic-metallic gas is used as an organic gas, the decomposed deposit with which the nanotube is fasten can be made a conductive metal film. By this strong conductive film, the nanotube and the cantilever are certainly electrically connected, so that a voltage can be applied to flow current in the probe for the scanning type microscope. According to the present invention, since a semi-conduction silicon cantilever, an insulation silicon nitride cantilever or a cantilever coated with a conductive substance are utilized, by constructing a probe by means of combinations of the cantilever and nanotubes which possess various electric properties, the present invention can provide various probes for scanning type microscopes such as an insulation probe, semi-conductive probe, a conductive probe, etc. According to the present invention, since an unnecessary deposit heaped up at a nanotube probe needle is removed by irradiating an ion beam, the present invention can provide a clean probe for a scanning type microscope which develops the ability as is designed. According to the present invention, the present invention can provide a probe for a scanning type microscope, by which error information caused by an unnecessary deposit can be excluded by means of removing the unnecessary deposit at the tip end portion of a nanotube probe needle, and furthermore for which a second process such as a formation of a conductive film is easily performed by means of removing an unnecessary deposit near the base end portion. According to the present invention, since an unnecessary part of a nanotube is cut off by irradiating an ion beam, oscillation of the tip end portion of the nanotube probe needle is eliminated so that resolution for the surface image of a specimen increases. Accordingly, the unification and increasing of the detection efficiency of a probe for a scanning type microscopes are achieved. According to the present invention, in a case where the nanotube is perpendicularly cut, the section area is caused to be least so that the section is formed to be neat, or in a case where the nanotube is obliquely cut, the tip end of the section is formed to be quite sharp, therefore, the probe can follow indentations and projections on the surface of a specimen, as the result, the detection resolution of the microscope increase. According to the present invention, since desired ions are shot into at least the tip end of the tip end portion of the nanotube probe needle, physical and chemical properties of the nanotube tip end portion can be changed as desired. Accordingly, the present invention can provide a probe for a scanning type microscope which sensitively reacts to specific physical and chemical actions from a specimen so that the probe for the scanning type microscope detects magnetic force and organic function groups of the surface of the specimen, and so on. For examples, by shooting ferromagnetic atoms into the tip end portion such as Fe, Co, Ni, etc. magnetism of the specimens can be effectively detected. According to the present invention, by injecting fluorine, boron, gallium, or phosphorus, etc. and by causing to combine them with constituent atoms of the nanotube, the specific qualities corresponding to the combinations can be developed in the nanotube probe needle. Needless to say, the present invention can be applied to cantilevers accompanied with the nanotubes which are manufactured by various apparatuses such as an electronic microscope or a focused ion beam apparatus.