JPH05346304A - Probe moving device for scanning tunnel microscope - Google Patents

Abstract

PURPOSE:To reduce the size of the probe moving device for scanning type tunnel microscope. CONSTITUTION:A supporting frame is attached to a base stage 1. First and second piezoelectric element units 3 and 4 are attached to the supporting frame. The control signal from a control circuit is sent into a driving power supply. Expansion deforming piezoelectric elements 3a and 4a are contracted, and a probe 7 is floated in air. At this instant, shear-deforming piezoelectric elements 3b and 45 are deformed without moving the probe 7. Furthermore, an expansion deforming piezoelectric element 3c is expanded, and the probe is kept at the different position. Under this state, the shear-deforming piezoelectic elements 3b and 4b are deformed into the moving direction of the probe, and the probe is moved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe moving device of a scanning tunneling microscope for coarsely moving a probe of a scanning tunneling microscope.

[0002]

2. Description of the Related Art In a scanning tunneling microscope, it is necessary to place a probe extremely close to a sample. Therefore, it is necessary to adjust the position of the probe. In order to perform this position adjustment, various probe moving devices have been proposed. Among such a probe moving device, there is a device in which the probe moving device is downsized by electrically driving the piezoelectric element to move the probe.

[0003]

In any of the probe moving devices using the above-mentioned piezoelectric element, at least two pairs of piezoelectric element element units are used for moving the probe,
It was not possible to make the probe moving device small enough.

An object of the present invention is to solve such conventional problems and to provide an extremely compact probe moving device.

[0005]

Therefore, according to the present invention, there is provided a piezoelectric element unit in which a shear deformation piezoelectric element and a stretch deformation piezoelectric element are laminated, and a pair of the piezoelectric element units are arranged above and below the probe so as to hold the probe. Of the scanning tunneling microscope including a mechanism for arranging the piezoelectric element units so as to face each other, and a driving unit for driving the piezoelectric element units so that the expansion deformation and the shear deformation of the piezoelectric element units occur at the same cycle. It features a needle moving device.

[0006]

When the elastic deformation piezoelectric element is contracted to lift the probe, the shear deformation element is deformed, and the elastic deformation element is further extended to hold the probe at different positions. The probe is moved by deforming the direction of movement of the probe.

[0007]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a view for explaining one embodiment of the present invention in detail, and FIG. 2 is a view taken along the line AA 'in FIG. In both figures, 1 denotes a base, and a support frame 2 is provided on the base 1.
Is attached. On the other hand, the first piezoelectric element unit 3 is mounted on the base 1. Also, the support frame 2
A screw 5 is screwed onto the top of the. A coil spring 6 is attached to the screw 5, and a second piezoelectric element unit 4 is attached to the tip of the coil spring 6. The first piezoelectric element unit 3 is configured by laminating a stretchable deformation piezoelectric element 3a, a shear deformation piezoelectric element 3b, and a pressing plate 3c. Similarly, the second piezoelectric element unit 4 includes an expansion / contraction piezoelectric element 4a, a shear deformation piezoelectric element 4b, and a pressing plate 4c.
And a mounting plate 4d. Reference numeral 7 denotes a probe, a depression U for receiving the probe is formed in the pressing plates 3c and 4c, and the probe 7 is held by a pair of piezoelectric element units 3 and 4. Therefore, by rotating the screw 5, the strength of the force for holding the probe 7 can be adjusted. Since the sample is two-dimensionally scanned on the base 1, a scanning unit 8 including a piezoelectric element is used.
Is mounted, and the sample 9 is mounted on the scanning unit 8. Reference numeral 10 is the elastically deformable piezoelectric element 3a, 4
It is a drive power source for driving the a and the shear deformation piezoelectric elements 3b and 4b, and the supply of voltage from the drive power source 10 to each element is performed based on a control signal from the control circuit 11.
Reference numeral 12 is a movement indicator for instructing movement of the probe.
The movement indicator 12 can indicate the start and stop of movement and the direction of movement.

In such a structure, the movement indicator 12
When an instruction to move the probe 7 toward the sample 9 is issued by the control circuit 11, a control signal is sent from the control circuit 11 to the driving power source 10, and the expansion / contraction piezoelectric elements 3a and 4a are both deformed as shown in FIG. 3 (a). And shear deformation piezoelectric elements 3b and 4b
Both deform as shown in FIG. In FIG. 3A, the vertical axis represents the expansion / contraction amount of the piezoelectric element, and the horizontal axis represents time. In addition, in FIG. 3B, the vertical axis represents the amount of shear deformation, and the horizontal axis represents time. As is clear from these figures, the elastically deformable piezoelectric elements 3a, 4
When “a” contracts at a high speed and the probe 7 momentarily floats in the air, the shear deformation piezoelectric elements 3b and 4b undergo shear deformation at a higher speed. As a result, at time t1 in FIG. 3, as shown in FIG. 4 (a), the position of the probe 7 in the horizontal direction remains unchanged, and the positions of the pressing plates 3c and 4c are retracted from the initial position.
As shown in FIGS. 3A and 3B, at the next timing, the elastically deformable piezoelectric elements 3a and 4a expand while the deformation of the shear deformable piezoelectric elements 3b and 4b remains unchanged. As a result, as shown in FIG. 4 (b), at time t2,
The probe 7 has a pressing plate 3c for pressing the body different from the initial state.
Held by 4c. Further, at the next timing, the shear deformation piezoelectric elements 3b and 4b are deformed while maintaining the stretched deformation piezoelectric elements 3a and 4a in the expanded state. As a result, the state at time t3 is as shown in FIG. 4C, and the probe 7 has moved to the sample 9 side by a unit amount.
In this state, the elastically deformable piezoelectric elements 3a and 4a are rapidly contracted again, and when the probe momentarily floats due to this contraction, the shear deformable elements 3b and 4b can be deformed more rapidly in the direction opposite to the sample. For example, the state of FIG. 4A is reproduced with the probe 7 moved by a unit amount to the sample side. Hereinafter, the probe 7 can be gradually moved by repeating the same process as the first case.

To retract the probe 7, the elastically deformable piezoelectric elements 3a, 4a are contracted and the shear deformable piezoelectric elements 3b, 4b are deformed toward the sample at the moment the probe 7 floats in the air. You can do it.

In order to enable the above-described operation, the maximum value V of the drive voltage for driving the elastic deformation piezoelectric elements 3b, 4b, the elastic deformation piezoelectric elements 3b, 4b and the shear deformation piezoelectric elements 3a, 4a are set. The following conditions are necessary for the cycle of the drive voltage for driving.

Now, when the acceleration of gravity is expressed by g, it is assumed that the probe 7 is pushed by the coil spring 6 with a force of about 2 g. In such a setting, if the time elapsed from the time when the expansion / contraction amount deformation piezoelectric element 3a starts contracting is represented by t, the probe is 3 in total due to its own weight and the force from the coil spring 6.
It will move downward with an acceleration of g. Therefore, if the fall distance at the time t has elapsed is L (t), L
(T) is expressed as follows. L (t) = (1/2) · 3gt ² When t1 is set to 10 μs and the fall distance is calculated based on the above equation, the fall distance is 14 Å, and the probe 7 falls only to this extent. Therefore, if the piezoelectric element is driven at a frequency of 100 KHz, it is sufficient to deform the shear deformation piezoelectric elements 3b and 4b and move the probe while the probe 7 is slightly falling and is floating in the air. It is possible. Also,
Assuming that the piezoelectric constant of the expansion / contraction deformation piezoelectric element in the expansion / contraction direction is d11, the contraction amount of the expansion / contraction deformation piezoelectric element 3a by time t1 is d11 · V. Therefore, d11 · V >> 14 angstroms are required. However, it is sufficiently possible to select the characteristics of the piezoelectric element and the applied voltage in this way.

The above-described embodiment is only one embodiment of the present invention, and the present invention can be modified and implemented.

For example, in the above-described embodiment, the shear deformation piezoelectric element is attached to the tip of the expansion / contraction piezoelectric element, but the stacking order may be reversed.

[0015]

As is apparent from the above description, in the probe moving device in the scanning tunneling microscope according to the present invention, the probe is held by the pair of piezoelectric element units, so that it becomes extremely compact, The miniaturization of the scanning tunnel microscope can be greatly advanced.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section of an embodiment of the present invention.

FIG. 2 is a view taken along the line AA ′ of FIG.

FIG. 3 is a timing diagram showing expansion and contraction and shear deformation of a piezoelectric element.

FIG. 4 is a diagram showing an operation state at each timing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base 2 Support frame 3,4 Piezoelectric element unit 3a, 4a Expansion deformation piezoelectric element 3b, 4b Shear deformation piezoelectric element 3c, 4c Holding plate 4d Mounting plate U recess 5 Screw 6 Coil spring 7 Probe 8 Scanning unit 9 Sample 10 Drive Power supply 11 Control circuit 12 Movement indicator

Claims (1)

[Claims] 1. A piezoelectric element unit in which a shear-deformation piezoelectric element and a stretch-deformation piezoelectric element are laminated, and a mechanism for arranging a pair of the piezoelectric element units so as to face each other above and below the probe so as to hold the probe. A probe moving device for a scanning tunneling microscope, comprising: and a driving means for driving both the piezoelectric element units so that expansion and contraction deformation and shear deformation of the both piezoelectric element units occur in the same cycle.