JPH02284006A - Probe fixing mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a mechanism for accurately fixing a microdetector such as a probe. In particular, the invention relates to a fixing mechanism commonly used as a probe holding mechanism for scanning tunneling microscopes.

[Conventional technology]

A scanning tunneling microscope (hereinafter abbreviated as STM) that can observe the surface of an object with atomic-scale resolution in real space.
It operates not only in vacuum, but also in the air and in liquids, and its application fields are wide-ranging, including surface roughness measurement, semiconductors, biomolecules, chemical reactions, and ultrafine processing. Recently, ST
As the practical application of M progressed, it began to be easily used in a wide range of fields.

This scanning tunneling microscope applies a voltage between a conductive sample and a conductive probe, and when they are brought close to a distance of about 1 nm, a tunnel current flows, and the tunnel current changes exponentially depending on the distance. It was used. As a probe, the tip of which has been polished to a very sharp point by electrolytic polishing etc. is used to keep a constant distance from the sample surface made of conductive material and scan it two-dimensionally. The tunneling current changes and a surface image can be obtained ("Fixed Physics JVO 1, 22, N.

3.1987. pp176-186).

Conventional STM probe fixing mechanisms include a mechanism that utilizes elastic force (Figures 5 and 6), a fixation mechanism using screws (Figure 7), or a mechanism in which the probe is integrated with a jig in advance. A mechanism for fixing the jig (Figure 8) was used.

[Problems to be Solved by the Invention] However, the conventional mechanism using elastic force described above has the following drawbacks. (1) The probe may move during STM operation, making it difficult to maintain a stable state at the atomic level. (2) Stick-slip occurs due to fixation due to elastic force and friction, making it difficult to position the probe in the axial direction when fixed.

(3) In order to fix the probe under the same conditions, it is necessary to finish the shape of the spring that provides the elastic force and the probe itself with high precision.

(4) Materials with elastic force have a phenomenon called creep, which is inconvenient for fixing.

Furthermore, fixing with screws has the following drawbacks.

(1) During STM operation, the screw may loosen, resulting in the probe moving. Further, if a double lock mechanism is used to prevent this, the structure becomes complicated. (2) A large space is required to provide screws around the probe fixing part.

On the other hand, fixing using a jig has the following drawbacks. (
1) Mechanism size becomes larger. (2) The assembly process for fixing the probe and jig increases.

Furthermore, the probe must be fixed manually by the STM user, and it takes a considerable amount of time to become proficient in the operation.It is desirable to improve operability, especially when changing the probe in a vacuum. was.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and it is possible to easily perform the work of attaching and fixing a probe with high precision, and is particularly suitable for a scanning tunneling microscope or an application device thereof. The purpose is to provide a fixing mechanism.

(Means for Solving the Problems) In order to achieve the above object, a probe fixing mechanism according to the present invention includes an electromechanical energy conversion element for holding a tunnel current detection probe at a constant value.

[Effect]

By applying a voltage to the electromechanical energy conversion element, the element expands and contracts, and this expansion and contraction fixes and releases the probe.

According to the present invention, by providing a fixing mechanism using an electromechanical energy conversion element, the probe can be easily fixed with high precision.

Furthermore, by providing an electrode on the part that comes into contact with the probe, the presence or absence of the probe and its fixed state can be detected.

〔Example〕

FIG. 1 is a sectional view showing a probe holding state of the probe fixing mechanism according to the present invention.

1 is a probe, 31 is a probe electrode that sandwiches the probe, 30 is an insulator,
20 is a piezoelectric ceramic, and 21 and 22 are internal and external electrodes for applying voltage to the piezoelectric ceramic 20. Moreover, FIG. 2 is a front view of the fixed probe 1 seen from the tip side.

The probe electrode 31 is divided into two parts, a probe electrode A32 and a probe electrode 8iB33. As shown in FIG. 1, from each electrode, a probe lead wire A34, a probe lead wire B35,
An internal lead wire 23 and an external lead wire 24 are drawn out and connected to an electric circuit (not shown). Piezoelectric ceramics 2
0 is polarized so as to be displaced in the circumferential direction (spreading direction) by applying a voltage between the electrodes 8i21 and 22.

FIG. 3 is a block diagram showing an example of a control system of the present invention.

Signals from the probe electrode 31 are connected to the switch 4 through lead wires 34 and 35. The switch 4 serves to connect the signal from the probe to the tunnel current measuring section 5 when the signal is used as STM, and to connect to the probe fixation detection section 6 when the probe is fixed. The probe state detection unit 6 is a part that detects the state of the probe, and measures the impedance between the probe electrodes A and B32, 33 to check whether the probe is present or not and whether the probe is securely fixed. . In addition, when attaching and detaching the probe, the impedance between the probe electrode 31 (32 or 33) and the conductive probe attachment/detachment jig 8 via the probe 1 is measured, and when the probe 1 and the probe electrode come into contact, the voltage Sends an ON signal to the application section 7. The voltage application unit 7 applies a voltage to the piezoelectric ceramic through the lead wires 23 and 24 to cause displacement.

Next, using FIG. 4, the procedure for fixing the probe will be shown. The above-mentioned switch 4 is connected to the probe state detection circuit 6 side. First, in Figure (a), the probe 1 that has been treated by electric field polishing is grasped by the probe attachment/detachment jig 8 (Figure 3). Next, the probe 1 is brought into contact with the probe fixing part 3 as shown in FIG. This causes the voltage application section 7 to be
N signal is sent. This signal applies a voltage to the piezoelectric actuator 2, and the piezoelectric actuator is expanded in the circumferential direction as shown in FIG. Next, the probe 1 is inserted into the actuator 2 to a predetermined position as shown in FIG. As a result, an OFF signal is sent from the aforementioned probe state detection section 6 to the voltage application section 7. Therefore, the piezoelectric actuator 2 contracts in the circumferential direction to fix the probe 1, as shown in FIG. In this state, as described above, the impedance between the two divided probe electrodes is measured by the probe state detection section 6 to confirm whether the probe is securely fixed. Then, the switch 4 is switched to the tunnel current measuring section 5 side, and the probe fixing work is completed.

To remove the probe, simply follow the steps described above in reverse.

In the above-mentioned embodiment, the circuit from the probe state detection section 6 to the voltage application section 7 can be used as the circuit of the S7M device. Specifically, in FIG. 3, the sample/bias voltage of the S7M device is configured to be applied to the probe attachment/detachment jig 8, and the presence/absence of the probe can be detected by the tunnel current measuring section. Furthermore, the same effect as in the above embodiment can be achieved by applying a signal for controlling the distance between the probe and the sample in the constant tunnel current mode of the S7M device to the piezoelectric ceramic.

Furthermore, the shape and materials of the piezoelectric ceramics are not limited to the above embodiments, and can be arbitrarily selected depending on the purpose. For example, a laminated type can be used so that it can be driven with a low voltage, and it is also possible to have a rectangular cross-sectional shape to ensure consistency with the fixed part.

Although piezoelectric actuators are used in the embodiments described above, any electromechanical energy conversion element can be used.

〔Effect of the invention〕

As explained above, by providing a fixing mechanism using an electromechanical energy conversion element, the probe can be easily fixed with high precision.

Furthermore, by providing a probe electrode on a fixed part that comes into contact with the probe, it is possible to grasp the presence or absence of the probe and its fixed state. This improves operability and securely fixes the probe. Furthermore, automatic attachment and detachment of the probe becomes possible, which is particularly useful in vacuum compatible STM.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the probe holding state of the probe fixing mechanism according to the present invention, FIG. 2 is a front view of the probe tip side of the probe fixing mechanism of FIG. 1, and FIG. A control block diagram of the probe fixing mechanism, FIG. 4 is an explanatory diagram of the probe mounting operation of the present invention, and FIG.
8 to 8 are cross-sectional views of conventional probe fixing mechanisms. 1: Probe, 2: Piezoelectric actuator, 3: Probe fixing part, 20: Piezoelectric ceramics, 21.22: Electrode, 31.32, 33: Probe electrode.

Claims (7)

[Claims] (1) A probe fixing mechanism comprising an electromechanical energy conversion element for fixing and holding a tunnel current detection probe. (2) The probe fixing mechanism according to claim 1, wherein the electromechanical energy conversion element comprises a piezoelectric actuator. (3) The probe fixing mechanism according to claim 1, wherein the piezoelectric actuator has a laminated structure. (4) The probe fixing mechanism according to claim 1, further comprising an electrode that comes into contact with the probe while holding the probe. (5) The probe fixing mechanism according to claim 4, wherein the electrode is divided into a plurality of parts. (6) The probe fixing mechanism according to claim 4, wherein the electrode is connected to a probe state detection circuit. (7) The probe fixing mechanism according to claim 6, wherein the probe state detection circuit is electrically connected to a probe mounting jig.