JPH08105903A - Piezoelectric driving device - Google Patents

Abstract

PURPOSE: To provide a piezoelectric driving device in which a high speed probe scanning can be performed without mutually interfering the displacements in X, Y, Z directions of piezoelectric driving members. CONSTITUTION: This device is formed of a first piezoelectric driving member 1 having one end fixed, which is displaced in Y-direction; a second piezoelectric driving member 2 provided on the other end of the first piezoelectric driving member 1, which is displaced in X-direction right-angled to the displacing direction of the first piezoelectric driving body; a third piezoelectric member 2 provided on the free end side of the second piezoelectric driving member 2, which is displaced in Z-direction vertical to the displacing directions of the first and second piezoelectric driving members; and a probe 4 for scanning over a sample provided on the free end side of the third piezoelectric driving member to detect local information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric drive device in a scanning probe microscope.

[0002]

2. Description of the Related Art A three-dimensional driving device in a scanning probe microscope is used for in-plane scanning in the X and Y directions and a constant distance between a sample surface and a probe for measuring unevenness of an atomic scale on the sample surface. It is necessary to move in the Z direction while maintaining
Conventionally, a probe or sample driving device in a scanning probe microscope has been driven by using a tripod type driving device or a tube type driving device.

FIG. 3 shows an example of a tripod type driving device. The tripod type driving device has a structure in which three piezoelectric driving members in the X, Y, and Z directions are gathered at the apexes. One end of the piezoelectric drive member in the X and Y directions is fixed among the piezoelectric drive members in the three directions. Therefore, the displacements in the X and Y directions interfere with each other, and the obtained image is distorted from the actual surface. In order to prevent this, when a voltage is applied between the electrodes of the driving member in the X direction, the other piezoelectric driving member in the Y direction is driven and displaced in the X direction.

FIG. 4 shows an example of a G.G. It was proposed by Binnig et al. (Re
v.Sci.Instrum.57 (8), 1986) The structure of the tube type driving device has a ground electrode 11 inside the tube type piezoelectric driving member 10 and four divided electrodes 12 outside. . The driving method is to apply positive and negative voltages to opposite electrodes on the outside,
The tube-type piezoelectric drive member bends in the lateral direction (arrow in the figure), whereby scanning drive in the X direction or the Y direction is performed. Further, in the Z-direction driving, the same voltage offset is applied to each of the outer electrodes 12, and the tube-type piezoelectric driving member expands and contracts to realize fine movement driving.

Further, in the scanning probe microscope, in order to observe a fast dynamic phenomenon on the surface of the sample, it is required to speed up the scanning of the probe.

[0006]

In the scanning drive of the above-described conventional tripod type and tube type drive devices,
There is a drawback that the displacements in the X, Y and Z directions interfere with each other. Further, the conventional driving device has a problem that an image obtained from the sample surface is distorted from the actual surface due to the interference of the displacements of these piezoelectric driving members.
In addition, there is no conventional driving device that performs high-speed probe scanning with less displacement interference.

It is an object of the present invention to provide a piezoelectric type driving device in which displacements of the piezoelectric driving members in the X, Y and Z directions do not interfere with each other and high speed scanning of the probe is possible.

[0008]

In order to achieve the above object, the present invention provides a first piezoelectric driving member having one end fixed to generate a displacement in the Y direction, and another first piezoelectric driving member. A second piezoelectric drive member that is displaced at an end in the X direction perpendicular to the displacement direction of the first piezoelectric drive member, and the second piezoelectric drive member is provided at the free end side of the second piezoelectric drive member. First
And a third piezoelectric driving member that generates a displacement in a Z direction perpendicular to the displacement direction of the second piezoelectric driving member, and a free end side of the third piezoelectric driving member is scanned on the sample to display local information. And a probe for detecting.

[0009]

In this claim, the piezoelectric driving member means
It is a generic term that includes laminated piezoelectric elements and electrodes that drive them. When trying to measure the fine irregularities on the sample surface, the control voltage is changed with time. At this time, the resonance frequency of the piezoelectric driving member becomes a problem. If the frequency components of the change over time of the control voltage are all sufficiently lower than the resonance frequency of the piezoelectric drive member, the displacement with large phase efficiency and small phase delay is generated in proportion to the amplitude of the control voltage. You can Therefore, the higher the resonance frequency of the piezoelectric drive member, the more efficiently the piezoelectric drive member can be expanded and contracted with high efficiency, and the piezoelectric drive member can sufficiently follow the change in the control voltage. According to the piezoelectric driving device of the present invention, displacement interference does not occur, and the resonance frequency of the device can be increased.

The piezoelectric driving device of the present invention is particularly effective for a scanning probe microscope which requires high speed scanning of a probe on the surface of a sample having fine irregularities.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of a piezoelectric drive device according to the present invention. In the piezoelectric drive device of the present invention, one end 6 of the first piezoelectric drive member 1 that is driven to be displaced in the Y-axis direction is fixed, and the other end is a free end. The free end of the first piezoelectric drive member is arranged so that one end of the second piezoelectric drive member 2 that is driven to be displaced in the X-axis direction is displaced toward the free end side in a direction perpendicular to the displacement direction of the first piezoelectric drive member 1. Fixed on the side. One end of the third piezoelectric drive member 3 which is displaced in the Z direction is fixed to the free end side of the second piezoelectric drive member so as to be displaced in the direction perpendicular to the first and second piezoelectric drive members. Further, the probe 4 for scanning the sample surface 5 is provided on the free end side of the third piezoelectric driving member.

Next, the operation of driving the piezoelectric driving device of the present invention in the XYZ directions will be described. While the first piezoelectric drive member 1 which is displaced in the Y direction is expanded and contracted in the Y direction, X
And the second and third piezoelectric type driving members 2 and 3 which are displaced in the Z direction only move in parallel. Therefore,
There is no interference between the displacement in the Y direction and the displacement in the X and Z directions.

Further, while the second piezoelectric drive member 2 which is displaced in the X direction is expanded and contracted, the third piezoelectric drive member 3 which is displaced in the Z direction only moves in parallel. Therefore, the X-direction displacement and the Z-direction displacement do not interfere with each other. Figure 2
FIG. 4 is a conceptual diagram of a configuration when the piezoelectric drive device of the present invention is mounted in a scanning probe microscope.

The piezoelectric drive device of the present invention is fixed below a substrate 6 supported by three micrometers 7 for adjusting the positions of the sample 5 and the probe 4. Here, the operation of the piezoelectric driving device of the present invention when the probe 4 scans the uneven shape of the sample surface 5 at the video rate will be described based on a specific example. An example will be given in which the probe scanning samples one image at 256 lines. Video rate is 30Hz
Is. Therefore, the first piezoelectric driving member 1 that generates a displacement in the Y direction has a frequency of 30 Hz and the second piezoelectric driving member 1 that generates a displacement in the X direction.
The piezoelectric driving member 2 of about 8 KHz (30 × 256 = 768
0) must be scanned.

Among the commercially available piezoelectric driving members, those which satisfy these resonance frequencies and have a wide scanning range as much as possible have a resonance frequency of about 35 KHz.
Some have a maximum displacement of 40 μm. Further, consider the resonance frequency required for the piezoelectric drive member in the Z direction. 25
When the data of 6 points is sampled, the maximum frequency of the sampling data is 128 times the resonance frequency in the X direction. However, considering that the actually obtained data is imaged, it is realistic to image up to about 50 times the frequency component in the X direction. Therefore, Z
Direction piezoelectric drive member is configured to generate a second displacement in the X direction.
It is sufficient to have a resonance frequency of about 400 KHz, which is 50 times that of the piezoelectric driving member. Here, satisfying these resonance frequencies among the commercially available piezoelectric drive members,
Resonance frequency of about 400KH for wide scanning range
z, maximum displacement is 3 μm. Thus, X, Y,
By using these commercially available piezoelectric drive members in the Z direction in the piezoelectric drive device of the present invention, it becomes possible to easily scan the probe at a video rate.

Since the first piezoelectric driving member 2 fixed to the fixed end 6 and driven to be displaced in the Y direction scans at a relatively slow speed of 30 Hz, the piezoelectric bonded to the free end side. The influence of the mass of the driving members 2 and 3 on the scanning can be ignored. In order to compare the piezoelectric type driving device of the present invention with a conventional tube type piezoelectric driving device, a displacement width of 20 μm will be obtained by using a commercially available piezoelectric driving member in the XYZ directions of the tube type piezoelectric driving device. Consider the example. The resonance frequency in each displacement direction is approximately 1 KH in the XY directions.
The resonance frequency in the z and Z directions is about 50 KHz.
Therefore, scanning of the probe at the video rate is impossible.

As described above, by using the piezoelectric driving device of the present invention, it is possible to obtain a wide scanning range by using a commercially available piezoelectric driving member and easily realize high-speed scanning.

[0018]

According to the configuration of the driving device of the present invention, X,
The drives in the displacement directions of the Y and Z axes do not interfere with each other. Therefore, a correction circuit is not required for controlling the drive voltage, and the drive member can be easily driven independently.
The scanning range has become wider. Further, since the piezoelectric driving device of the present invention can increase the resonance frequency as compared with the tube type piezoelectric driving device which has been widely used in the past, it is possible to scan the probe at higher speed. .

[0019]

[Brief description of drawings]

FIG. 1 is a configuration diagram of a piezoelectric driving device of the present invention.

FIG. 2 is an operation explanatory view of the piezoelectric driving device of the present invention in the scanning probe microscope.

FIG. 3 is a configuration diagram of a conventional tripod-type drive device.

FIG. 4 is a configuration diagram of a conventional tube drive device.

[Explanation of symbols for main parts]

 DESCRIPTION OF SYMBOLS 1 1st piezoelectric drive member (Y direction piezoelectric drive member) 2 2nd piezoelectric drive member (X direction piezoelectric drive member) 3 3rd piezoelectric drive member (Z direction piezoelectric drive member) 4 Probe 5 Sample 6 substrates 7 micrometers

Claims (1)

[Claims] 1. A piezoelectric drive device for generating displacement in three directions of X, Y and Z directions, wherein a first piezoelectric drive member having one end for generating displacement in the Y direction is fixed, and the first piezoelectric drive member. A second piezoelectric drive member, which is provided at the other end of the drive member, generates a displacement in an X direction perpendicular to the displacement direction of the first piezoelectric drive body, and a second piezoelectric drive member is provided on the free end side of the second piezoelectric drive member. A third piezoelectric driving member that generates a displacement in a Z direction that is perpendicular to the displacement direction of the first and second piezoelectric driving members that are provided, and a third piezoelectric driving member that is provided on the free end side of the third piezoelectric driving member. A piezoelectric driving device comprising: a probe that scans a sample to detect local information.