JP3914826B2 - Probe manufacturing method and probe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a probe manufacturing method for a scanning probe microscope and the probe.
[0002]
[Prior art]
A scanning Kelvin probe microscope (SKPM) included in a scanning probe microscope (SPM) is an apparatus that applies the Kelvin method (vibration capacity method) to an atomic force microscope that is a kind of SPM. This scanning Kelvin probe microscope has a cantilever with a conductive probe, detects the displacement of the cantilever that is displaced according to the electrostatic force acting between the conductive probe and the sample, and the detection result This is a device that calculates the local potential of the sample surface based on this and performs potential mapping of the sample surface.
[0003]
Conventionally, as the above-described conductive probe, a probe having a metal coating applied to the entire surface or a conductive probe in which the entire surface is ion-sputtered so as to have good conductivity are used.
[0004]
[Problems to be solved by the invention]
However, when such a probe having conductivity over the entire surface is used, the electrostatic force, which is a long-distance force (a force acting over a long distance), is a wide area of the entire probe and the sample surface. Act in between. For this reason, conventionally, the sample potential in a minute region immediately below the tip of the probe cannot be obtained, and a high-resolution sample potential map cannot be obtained.
[0005]
The present invention has been made in view of the above points, and an object of the present invention is to provide a probe capable of accurately measuring the potential of a micro area on the surface of a sample, and a method for producing the probe. is there.
[0006]
[Means for Solving the Problems]
In the probe manufacturing method of the present invention that achieves this object, the distance between the probe tip and the sample is adjusted so that oxygen molecules cannot enter between them, and then the probe is oxidized. .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0008]
FIG. 1 is a view showing an apparatus for producing the probe of the present invention. In FIG. 1, reference numeral 1 denotes a vacuum vessel, and the inside (vacuum chamber) 2 of the vacuum vessel 1 is exhausted to a high vacuum by an exhaust device 3.
[0009]
4 is an oxygen supply device, and the oxygen supply device 4 is connected to the vacuum vessel 1. The oxygen supply device 4 is for supplying heated oxygen to the vacuum chamber 2.
[0010]
Reference numeral 5 denotes a sample stage, and the sample stage 5 is disposed in the vacuum chamber 2. A conductive sample 6 is placed on the sample stage 5.
[0011]
A cantilever 7 for a scanning Kelvin probe microscope is attached to a moving mechanism 8 disposed in the vacuum chamber 2. The cantilever 7 is made of a cantilever 7a and a probe 7b attached to the tip of the cantilever 7a. The probe 7b is made of, for example, Si coated with Pt. Thus, the probe 7b has conductivity, and in this example, a Pt-coated Si cantilever is used. The moving mechanism 8 is made of a piezo element or the like so as to be movable in the x, y, and z directions.
[0012]
In FIG. 1, 9 is a bias voltage applying device. The bias voltage applying device 9 is for applying a bias voltage between the above-described conductive probe 7 b and the conductive sample 6.
[0013]
Reference numeral 10 denotes a tunnel current detector, and a tunnel current flowing between the probe 7 b and the sample 6 is detected by the detector 10. The output of the tunnel current detection device 10 is configured to be supplied to the movement mechanism control device 11, and the movement mechanism control device 11 controls the movement mechanism 8 based on the output of the tunnel current detection device 10.
[0014]
Reference numeral 12 denotes a central controller, and the central controller 12 supplies control signals to the oxygen supply device 4, the bias voltage application device 9, and the moving mechanism control device 11 described above.
[0015]
Although the apparatus configuration of FIG. 1 has been described above, the operation will be described below.
[0016]
When a probe for a scanning Kelvin probe microscope is manufactured, first, the central control device 12 supplies a bias voltage application instruction signal to the bias voltage application device 9. Upon receiving this signal, the bias voltage applying device 9 applies a predetermined bias voltage between the probe 7 b and the sample 6.
[0017]
Next, the central controller 12 supplies an approach signal to the sample 6 of the probe 7b to the moving mechanism controller 11. Upon receiving this approach signal, the movement mechanism control device 11 controls the movement mechanism 8 so that the movement mechanism 8 moves in the z direction (sample direction).
[0018]
The probe 7b approaches the sample 6 by the z movement of the moving mechanism 8, and when the probe 7b approaches the sample 6 considerably, a tunnel current starts to flow between them. Then, the moving mechanism control device 11 determines the z direction of the moving mechanism 8 when a predetermined tunnel current I ₀ (A) flows between the probe 7 b and the sample 6 based on the output of the tunnel current detecting device 10. Stop moving to (sample direction).
[0019]
Thus, the distance between the probe 7b tip and the sample 6 is fixed the tunnel I _{0 (A)} flows a distance d ₀ between them. The distance d ₀ between the probe tip and the sample is a distance (d ₀ <about 1 nm) in which oxygen molecules O ₂ (the size of O ₂ is 2.8 × 3.9 angstroms) cannot enter between them. The relationship between the distance d ₀ and the tunnel current I ₀ (A) is determined in advance by experiments.
[0020]
As described above, when the distance between the probe tip and the sample is set to such a distance that oxygen molecules cannot enter between them, the central controller 12 next sends an oxygen supply instruction signal to the oxygen supply device. Send to 4. Upon receiving this signal, the oxygen supply device 4 sends heated oxygen gas corresponding to the oxygen partial pressure and the degree of vacuum into the vacuum chamber 2 for a predetermined time.
[0021]
By supplying this oxygen gas, the atmosphere around the probe becomes a heated oxygen gas atmosphere, and the probe 7b is oxidized.
[0022]
However, since the heated oxygen gas cannot enter between the tip of the probe 7b and the sample 6, the tip of the probe 7b is not oxidized. That is, the tip of the probe 7b remains exposed with the conductive probe. As a result, as shown in FIG. 2, the probe of the present invention covered with an oxide film except for the tip portion of the probe is generated.
[0023]
If the probe thus completed is used as a probe for SKPM, the electrostatic force acts between the tip of the probe not covered with the oxide film and the sample. As a result, it is possible to obtain the sample potential in the minute region immediately below the probe tip, and to obtain a high-resolution sample potential map.
[0024]
As mentioned above, although an example of probe production of the present invention was explained, the present invention is not limited to the above-mentioned example.
[0025]
For example, in the above example, heated oxygen gas is supplied to the vacuum chamber. However, room temperature oxygen gas is supplied to the inside of the vacuum vessel (vacuum chamber) heated by the heater, and oxygen gas is supplied in the vacuum chamber. You may make it heat.
[Brief description of the drawings]
FIG. 1 is a view showing an apparatus for producing a probe of the present invention.
FIG. 2 is a view showing a probe of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Vacuum container, 2 ... Vacuum chamber, 3 ... Exhaust device, 4 ... Oxygen supply device, 5 ... Sample stage, 6 ... Conductive sample, 7 ... Cantilever, 7a ... Cantilever, 7b ... Probe, 8 ... Movement Mechanism: 9 ... Bias voltage application device, 10 ... Tunnel current detection device, 11 ... Movement mechanism control device, 12 ... Central control device

Claims (4)

  A probe manufacturing method, wherein the probe is oxidized after adjusting the distance between the probe tip and the sample so that oxygen molecules cannot enter between them. The probe manufacturing method according to claim 1, wherein a distance d ₀ between the probe tip and the sample is adjusted to about d ₀ <1 nm.   2. The probe and the sample have conductivity, and a distance between the probe tip and the sample is adjusted based on a tunnel current flowing between the probe and the sample. Of making a probe.   4. The probe manufacturing method according to claim 1, wherein an atmosphere around the probe is changed to a heated oxygen gas atmosphere so that the probe is oxidized.

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