JP3234187B2 - Manufacturing method of electrochemical STM tip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a probe used for observing and processing a sample using electrochemical STM in the chemical industry, metal industry, electronic industry and the like.

[0002]

2. Description of the Related Art Conventionally, as a method for manufacturing an electrochemical STM probe, one end of a platinum or tungsten fine wire is sharpened by an electrochemical or mechanical method.
A method of coating the entire metal wire with a resin having an insulating property, and then removing the resin at the forefront portion with an organic solvent has been generally used. Another method for coating the entire metal wire with an insulating material is to selectively deposit a thin film of silicon nitride or silicon carbide on a portion other than the foremost portion using a CVD method so that the probe can be used. Examples of production have also been reported.

[0003]

In the tip of the electrochemical STM, it is necessary that a region having a diameter of 1 .mu.m or less at a tip portion is exposed and the other portion is completely covered with an insulating material. Therefore, these methods have the following problems. First, in the first method, when removing the resin at the forefront portion, sharpening is performed by immersing only the foremost portion of the resin coating in an organic solvent or exposing it to an atmosphere in which the organic solvent is volatilized. It exposes the tip of the metal wire. In such a method, the diameter of the tip is 1μ.
Skill is required to selectively remove the resin in only a minute region of m or less, and it is very difficult to keep the area of the exposed front end portion constant. In addition, since the dip coating method is generally used for coating the entire metal wire with a resin, the thickness of the insulating material other than the leading edge becomes thicker and the thickness must be uniform. Is also difficult.

In the second method, the surface of a metal wire used as a material for a probe of an electrochemical STM is not as smooth as a silicon wafer. In order to cover the entire metal wire without pinholes, it is necessary to make the film thickness very large, and there is a problem that it takes a long time to form the film. In order to further expose only the foremost part, the film is formed by the CVD method with the foremost part masked in advance, or after the film is formed by the CVD method, only the thin film at the foremost part is selectively selected. It must be removed, in each case further complicated steps are required. In addition, since the adhesion formed by such a method is not so high, there is a problem that if used for a long time, the insulating coating comes off from the leading edge portion.

[0005]

Therefore, in the present invention, the surface of a metal wire having a sharpened tip is coated with a photoresist by an electrodeposition method, and then only the sharpened tip is selectively exposed to light. By removing the resist, a very small area at the forefront is exposed. In the step of coating the metal wire by the electrodeposition method, the metal wire and the counter electrode are immersed in a solution in which a photoresist monomer is dispersed, and an insulating coating is formed by applying a voltage between the two. In such a method, the photoresist is deposited only on portions having conductivity, and the photoresist itself is insulative, so that no further photoresist is deposited on the portion once covered with the photoresist. Therefore, it is possible to make the film thickness thin and uniform without pinholes. Further, this step can be performed in a very short time as compared with the CVD method or the like.

In the step of removing the photoresist, only the operation of exposing and developing only the foremost portion of the photoresist can easily expose the foremost portion. In addition, as a step of performing this exposure, a submicron-order microscopic method is used, such as an exposure method using a mask used in a normal semiconductor manufacturing technique or a method of irradiating a focused laser beam to only the foremost part. Can be exposed. Furthermore, by using near-field light, it is also possible to expose only a finer region with a diameter of several nanometers to several tens of nanometers.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a method of manufacturing an electrochemical STM probe according to the present invention.
1 illustrates an apparatus used for a process of insulatingly covering an entire metal wire. In a container 101, an electrodeposition solution 102 in which an electrodeposition photoresist monomer is dispersed is placed, in which a metal wire 103 having one end sharpened in advance, and a counter electrode 1
04 is immersed. Further, the metal wire 103 and the counter electrode 1
04 is connected to a power supply 106 via a switch 105.
In the present embodiment, as the electrodeposition photoresist,
A positive type in which a portion irradiated with light causes a chemical change and dissolves in a developing solution, and an anion type in which an object to be coated is an anode at the time of electrodeposition was used. 200V applied voltage of power supply 106
When the switch 105 was turned ON for 60 seconds, the entire metal wire was uniformly covered with the photoresist film.

Next, FIG. 2 shows an apparatus used in the step of exposing only the foremost portion of the formed insulating film. The metal wire 103 covered with the electrodeposition resist is set on the holder 201. A mask 202 and a shutter 203 on which a fine opening pattern is formed are provided above the metal wire 103, and light from the light source 204 is applied to the tip of the metal wire 103 via these. ing. In the exposure step, first, the relative positions of the mask 202 and the metal line 103 are adjusted such that the minute opening formed on the mask 202 is located directly above the foremost part of the metal line 103. Next, the light source 204 is turned on, and when the light amount becomes stable, the shutter 203 is opened for an appropriate time, and only the leading end portion of the metal wire 103 is exposed. After the exposure is completed, development and rinsing are performed to remove only the photoresist at the foremost portion that has been modified by the exposure.

In the present embodiment, a positive electrodeposition resist is used. However, a negative electrodeposition resist, which becomes unnecessary in a developing solution due to cross-linking of light-irradiated portions, is used, and the pattern of the mask 202 is changed to a metal wire. The same effect can be obtained even when the pattern is such that light does not hit only the leading edge portion of 103. ◎ Embodiment 2 In this embodiment, the step of insulatingly coating the entire metal wire is the same as that of Embodiment 1, and then the step of exposing only the foremost portion of the formed insulating film is performed by laser light. The case where is used will be described. The electrodeposition resist used in the present embodiment is of a positive type.

FIG. 3 schematically shows an apparatus in which laser light is used for exposure. A metal wire 103 covered with an electrodeposition resist is fixed on a stage 301. Next, the stage 301 is moved and adjusted so that only the foremost portion of the metal wire 103 enters the irradiation range of the laser beam 302. Stage 3
When the adjustment of the position of 01 is completed, the laser light source 303 is turned on for an appropriate time, and only the leading end portion of the metal wire 103 is exposed. After the completion of the exposure, development and rinsing are performed in the same manner as in the first embodiment, and only the photoresist at the forefront portion modified by the exposure is removed. ◎ Embodiment 3 In this embodiment, the step of insulatingly covering the entire metal wire is performed in the same manner as in Embodiment 1, and thereafter, the near field is exposed to the step of exposing only the foremost portion of the formed insulating film. The case where light is used will be described. The electrodeposition resist used in the present embodiment is of a positive type.

FIG. 4 schematically shows an apparatus when near-field light is used for exposure. A metal wire 103 covered with an electrodeposition resist is set on a piezoelectric element 301 that can finely move in the XYZ directions. XY for coarse movement under the piezoelectric element 301
A Z-axis stage 302 is provided. On the other hand, an optical fiber probe that sharpens one end of an optical fiber, bends the sharpened portion into a hook, and further covers the portion other than the sharpened tip with a light reflecting film to provide a small aperture.
303 is arranged so as to face the tip of the metal wire 103. The optical fiber probe 303 has a laser light source 3 for exposure.
04 is connected.

In the exposure step in the present embodiment, first, using the coarse movement XYZ axis stage 302, adjustment is made so that the foremost portion of the optical fiber probe 303 and the foremost portion of the metal wire 103 are close to each other. After that, using the piezoelectric element 301 for fine movement, after adjusting the laser light source 304 after adjusting so that the foremost part of the metal wire 103 is included in the range of near-field light emitted from the minute opening at the tip of the optical fiber probe 303, This is done by turning ON for an appropriate time. After exposure is completed,
Development and rinsing are performed in the same manner as in 1 to remove only the photoresist at the foremost portion that has been modified by exposure.

In the present embodiment, by performing exposure using near-field light, the diameter of the exposed end of the metal wire 103 can be extremely reduced to several tens of nanometers.
The resolution of the electrochemical STM could be improved.

[0014]

According to the present invention, as described above,
When manufacturing an STM tip, the region with a diameter of 1 μm or less at the foremost part is exposed, and the other part can be completely covered with an insulating material. At that time, the process of exposing, developing, and rinsing is used as a method for selectively removing the coating on the forefront part, so that the area of the forefront part to be exposed can be made almost constant. Do not need. In addition, since the coating of the insulating material is performed by an electrodeposition method, it is possible to reduce the coating film thickness as compared with the dipping method, and even when compared with the CVD method,
It is possible to coat in a short time, there are few pinholes,
It is excellent in that it does not peel off for a long time because it has high adhesion to the metal wire.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing steps of a method for producing an electrochemical STM probe according to the present invention.

FIG. 2 is an explanatory view showing an apparatus used in a step of insulatingly covering the entire metal wire in the present invention.

FIG. 3 is an explanatory view showing an apparatus used in a step of exposing a foremost portion of a metal line in the present invention.

FIG. 4 is an explanatory diagram showing an apparatus used in a step of exposing the forefront portion of a metal wire using laser light in the second embodiment.

FIG. 5 is an explanatory view showing an apparatus used in a step of exposing the forefront portion of a metal line using near-field light in the third embodiment.

[Explanation of symbols]

 101 Container 102 Electrodeposition solution 103 Metal wire 104 Counter electrode 106 Power supply 202 Mask 203 Shutter 204 Light source 301 Stage 303 Laser light source 401 Piezoelectric element 402 XYZ axis stage for coarse movement 403 Optical fiber probe

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tatsuaki Ataka 1-8-1 Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Instruments Inc. (56) References JP-A-5-34106 (JP, A) JP-A Heihei JP-A-6-229964 (JP, A) JP-A-6-299390 (JP, A) JP-A-11-254238 (JP, A) JP-A-6-67009 (JP, A) JP-A-6-108292 (JP, A) A) JP-A-7-306307 (JP, A) JP 6-105262 (JP, B2) JP3062732 (JP, B2) Toshihiko Sakuhara, Masayuki Suda, Kunio Nakajima, Kazuyoshi Furuta, Yasuyuki Mitsuoka, Ryu Ataka Akira, “Development of Micro Electrochemical Machining and Micro Optical Machining Technology”, Proc. Of the 73rd Ordinary General Meeting of the Japan Society of Mechanical Engineers (4), The Japan Society of Mechanical Engineers, 1996, No. 96-1, p. . 476-477 Toshihiko Sakuhara and Masayuki Suda, “Micro-electrolytic processing and optical processing techniques”, Electronics, Ohmsha Co., Ltd., April 1997, p. 33-36 (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 13/10-13/24 G12B 21/00-21/24 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A probe having a very small tip and covered with a material having an electrical insulating property except at the tip thereof is brought close to a sample in an electrolyte solution to measure the shape of the sample surface or to perform electrochemical measurement. In the electrochemical STM for measuring static information or performing electrochemical processing, a step of sharpening one end of a metal wire with the probe, a step of coating the entire metal wire with an insulating material, and a step of sharpening the metal wire The insulating material is manufactured by a process of selectively removing only the insulating material at the foremost portion, and the insulating material or the precursor thereof is separated.
Immerse the object to be coated and the counter electrode in the
The surface to be coated by applying a voltage between
Has the property of being sharpened when exposed to light.
In the process of removing the insulating material on the cutting edge
Is a substance having a property that changes to a possible substance, or the insulating substance is the insulating substance or the insulating substance.
In the liquid in which the precursor is dispersed, the coating target and the counter electrode
Immerse and apply voltage between them to cover
It has the property of covering the surface, and in the state where it is not exposed to light,
Removing the insulating material on the sharpened tip portion
Has properties that can be removed in
Removing the insulating material on the sharpened tip.
It has the property of changing to a substance that cannot be removed in the process
Is any substance, process of coating the entire metal wire with an insulating material, the insulating
In a liquid in which the substance or its precursor is dispersed,
Is installed around the metal wire, and a voltage is applied between the two.
By selecting only the insulating material at the sharpened tip of the metal wire,
Selective removal process is selective for the cutting edge insulating material
Exposure process and the insulating material modified by the exposure
The step of dissolving in the solution, the step of selectively exposing the insulating material at the foremost portion,
The light from the light source is sharpened through the mask by the metal wire.
A step of selectively irradiating the metal wire with a sharp tip or a laser beam with a sharp tip of the metal wire.
A step of selectively irradiating a portion, or a sharpened tip of the metal wire with near-field light
A process for selectively irradiating the STM probe with an electrode.