JPS63274801A - Diamond probe - Google Patents

Abstract

PURPOSE:To obtain a hard and sharp probe tip by laminating diamond grains having electrical conductivity to the part of a metallic bar having a sharp pointed tip. CONSTITUTION:A rod wire such as stainless steel wire having about 1mm diameter or tungsten wire having about 0.3mm diameter is cut to an arbitrary length and the tip thereof is mechanically or electrolytically polished to prepare a metallic part 1 of the probe. This probe is placed in a gaseous mixture composed of hydrogen, gaseous methane and diborane and the diamond grains 2 are laminated and deposited thereon by using the nonpolar discharge of about 2.45GHz microwaves. After the surface of the diamond grains 2 is subjected to sputter cleaning, chromium is ion-implanted by about 150kv acceleration voltage. The grains deposited in such a manner are analyzed by the Raman scattered spectra of the laser to confirm that the grains are the diamond grains. The electrical conductivity is checked by measuring the resistance value. The shape condition at the microtip is observed by a scanning electron microscope.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a detection probe used in a detection section in the fields of analytical instruments and scanning tunneling microscopes.

[Summary of the invention]

This invention is a diamond probe in which conductive diamond grains are laminated on the tip of a metal rod with a sharp tip, and the final tip radius is formed by forming a corner of the diamond grain or a micro-grain shape. This makes it possible to form an extremely sharp tip of the probe, making it an industrially useful diamond probe.

[Conventional technology]

A scanning type that detects the tunnel current flowing between the sample surface and the tip of the detection probe, and controls the minute distance between the sample surface and the tip of the detection probe so that the tunnel current remains constant to observe the atomic structure. In a tunneling microscope, the resolution is determined by the state of the tip of the probe, and in order to increase the resolution, it is necessary to form a sharper probe. Conventionally, the tip of a platinum or tungsten rod was sharpened into a conical shape by mechanical polishing, or the tip was formed by electropolishing (Japanese Unexamined Patent Publication No. 61-32326, a needle-shaped rod by electropolishing). (formation method) is known.

[Problem that the invention seeks to solve]

With the probes manufactured by the conventional method shown above, mechanical polishing does not result in a smoothly elongated tip of the probe, resulting in a sharp tip shape, and with small wire diameters, the tip of the tip cannot be sharpened. If you hit it, it will escape, so the wire diameter is limited. In addition, according to the electrolytic polishing method, on the contrary, a smaller wire diameter is advantageous because the reaction time can be shortened, but if the timing of stopping the reaction is off, the reaction will occur at the tip of the probe, making it impossible to obtain a sharp shape. There's a problem.

Furthermore, when using a mechanically polished or electrolytically polished probe as described above, when performing rough positioning on the sample surface during scanning with a scanning tunneling microscope, even a light contact between the probe and the sample surface can cause the tip to collapse. However, if the coarse positioning mechanism is not stable, there is a problem in that the probe needs to be replaced frequently.

[Means for solving problems]

In order to solve the above problems, the present invention stacks conductive diamond grains on the tip of a metal rod with a sharpened tip. Ensure that the grain shape is at the cutting edge,
This made it possible to create a probe with an extremely sharp and hard tip.

[Effect]

By manufacturing the probe using the method described above, the leading edge of the probe can be formed by processing the corner of a relatively large diamond grain with good crystallinity, or even a diamond grain with poor crystallinity. By creating a particle shape that is smaller than the shape of the metal tip, it is possible to produce a probe with an extremely sharp and hard tip.

Example C] This example relates to a detection probe used in a detection section of a scanning tunneling microscope, and will be described below based on the drawings.

According to the probe manufacturing process shown in FIG. 4, first, the rond wire is cut to an arbitrary length. In this example, a φ11 stainless steel rond wire is cut to a length of approximately 20 sl, and a φ0.3 t.
The tungsten rondo wire of a was cut into approximately 20 square lengths), and the tip was mechanically polished (the tip had a conical shape of 120°) or electrolytically polished (tungsten wire), and then diamond synthesis was performed.

In this example, two methods were used to impart conductivity to diamond.

(First Example) A method for diamond synthesis in which diamond is deposited using microwave nonpolar discharge in a mixed gas of hydrogen, hydrocarbon (CHe), and diborane (BJi), which has the effect of lowering the resistance value of diamond grains. (Microwave plasma C
(VD method).

Using the apparatus shown in FIG. 5, the precipitation conditions were as shown in Table 1.

Table 1 Synthesis Conditions (Second Example) For diamond synthesis, first, hydrogen and hydrocarbon (CHJ
Diamond grains were precipitated by microwave plasma CVD in a mixed gas of . The precipitation conditions are shown in Table 2.

Table 2 Synthesis conditions Next, in order to make the diamond grains conductive, after sputter cleaning the surface of the diamond grains,
was ion-implanted. Is the amount of Cr implanted 2xlQl? 1
ons/cd, Cr ion implantation acceleration Tll pressure't
The test was carried out at a temperature of 150kv and a probe temperature of 200°C.

The precipitated grains were analyzed by laser Raman scattering spectroscopy using the two methods described above, and it was confirmed that they were diamond grains. Furthermore, the resistance value was measured and it was confirmed that it had electrical conductivity. Furthermore, when the tip of the probe was observed using a scanning electron microscope, it was found that a minute tip was formed by diamond grains as shown in Figures 1 and 2.
I was able to confirm 11.

When the probe thus prepared was actually incorporated into a device as a detection probe of a scanning tunneling microscope and tested, it was confirmed that stable high resolution could be obtained without the problems encountered with conventional products. was completed.

[Effects of the Invention] According to the present invention, as explained above, by stacking conductive diamond grains on the tip of a metal rod with a sharpened tip, the tip of the probe is determined by the shape of the diamond grains. , an extremely sharp probe tip was formed with good reproducibility, and since it was made of diamond particles, it became possible to produce an extremely hard probe tip.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the tip of the probe of the present invention, the second is an enlarged sectional view of the tip of the probe, Fig. 3 is a plan view showing diamond grains, Fig. 4 is an explanatory diagram of the probe manufacturing process, FIG. 5 is an explanatory diagram showing a diamond synthesis apparatus. 1... Probe metal part 2... Laminated part of diamond grains or more

Claims (1)

[Claims] A diamond probe is characterized by having an extremely sharp and hard tip made by laminating conductive diamond grains on the tip of a metal rod with a pointed tip.