JPH0769139B2 - Piezoelectric element micro positioning mechanism - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a minute positioning mechanism for minutely positioning a detection unit and a sample in the fields of analytical instruments and scanning tunneling microscopes.

[Outline of Invention]

The present invention aligns a detection unit or a sample fixed to the tubular piezoelectric element body finely and at high speed by the deformation of the piezoelectric element body caused by applying a voltage to the inside and outside of the tubular piezoelectric element body. Is what makes it possible,
This is a piezoelectric element minute positioning mechanism that is industrially useful.

[Conventional technology]

A scanning tunnel that detects the tunnel current flowing between the sample surface and the tip of the detection probe, and controls the space between the sample surface and the tip of the detection probe so that the tunnel current is constant, and observes the atomic structure. In a microscope, a three-dimensional micro-positioning mechanism that operates along the x and y directions of the sample surface and the unevenness of the sample surface is required. In the past, a piezoelectric element body formed integrally with the x and y axes and a rod-shaped piezoelectric element body for the z axis were combined (STM device sample 33rd Applied Physics Joint Conference Lecture (1986) Masatoshi Ono , Etc.) and a cubic piezoelectric element integrally formed with x, y, z axes (Proceedings of the 32nd Joint Lecture on Applied Physics (1985) Shigeo Okayama, etc.)
It has been known.

[Problems to be Solved by the Invention]

In the conventional piezoelectric element micro-positioning mechanism, the combination of the z-axis rod-shaped piezoelectric element body with the piezoelectric element body formed integrally with the x and y axes has a resonance frequency of several hundred Hz from a structural vibrational point of view. Since it is relatively low, there is no problem when the relative scanning speed between the sample surface and the detection probe is slow, but the control response speed between the sample surface and the detection probe tip is limited.

On the other hand, the cubic piezoelectric element body in which the x, y, and z axes are integrally formed may be formed to have a higher rigidity than the above structure because it is integrally formed. Since the resonance frequency can be increased, high speed scanning was possible.

However, since the cubic piezoelectric element body is obtained by cutting three axes from one piezoelectric element material, the rod-shaped piezoelectric element body may be slightly weak against lateral stress, and there is always a risk of breakage.

[Means for Solving the Problems]

In order to solve the above problems, the present invention provides at least one pair of electrodes inside and outside a tubular piezoelectric element body having a flat outer surface, a pair of electrodes, or a common electrode on one of the inside and the outside. A split electrode is provided on the other side to enable three-dimensional operation by the electrode configuration.

[Action]

By the method described above, a small and highly rigid micropositioning mechanism is formed, which is easy to handle and has high rigidity, so that the resonance frequency is high and high-speed scanning is possible. Moreover, since the outer surface has a flat surface, the accuracy with electrodes can be more easily obtained than that of a curved surface, and the mutual interference at the time of in-plane scanning (xy axis) of the sample can be mitigated.

〔Example〕

The present embodiment relates to a fine positioning mechanism for fine positioning between the detection probe of the scanning tunneling microscope and the sample, which will be described below with reference to the drawings.

〔Example〕

FIG. 1 shows a minute positioning mechanism according to a first embodiment of the present invention, in which an insulating material 2 and a metallic detection probe base 3 having a female screw thread are mounted on a piezoelectric element body 1. , The detection probe 5 fixed to the detection probe holder 4 with the external thread cut
Is incorporated in the detection probe base 3. As shown in FIG. 2, the piezoelectric element body 1 is a tubular piezoelectric element body in which both inner and outer circumferences are cut, and as shown in FIG. 3, an electrode x for x-axis operation is provided on the opposing outer peripheral surface of a quadrangular prism. ₁ , x ₂ and electrodes for y-axis operation y ₁ , y ₂
And an electrode z for z-axis operation common to each surface is provided, and an axis parallel to the axial direction of the tube (z-axis) and an axis orthogonal to the axial direction of the tube (x, y-axis = in-plane ). In addition, a common electrode 6 (GND) is formed inside the tube, and electrodes are attached by partially folding it back to the outer peripheral surface to facilitate wiring.

For example, the thick electric element is a tubular square column with a height of 12 mm, a width of 10 mm, and a wall thickness of 1.5 mm, and the x and y axis electrodes are 2 mm long, 8 mm wide, and the z axis electrodes are 6 mm long and the inner electrode folding width is Is 1 mm, and the joint width between each electrode is 1 mm. Next, the operation will be described. In the z-axis direction, a positive or negative voltage is applied to the inner electrode to displace the piezoelectric element body in the thickness direction, resulting in displacement in the z-axis direction. As shown in FIG. 9, the x- and y-axis directions are, for example, when operating in one direction of the x-axis, one of the opposing electrodes x ₁ and x ₂ , for example, the electrode x ₂ is a positive voltage with respect to the inner electrode. On the other hand, by applying a negative voltage to the electrode x ₁ here, for example, the piezoelectric element between the electrode x ₂ and the electrode GND is deformed in the contracting direction, and the piezoelectric element between the electrode x ₁ and the electrode GND extends. Transforms in the direction. As a result, the upper portion is tilted in the direction of the electrode x ₂ as shown in FIG. 9B, and as a result, the detection probe 5 is moved from the state (a) to the state (b) in which no voltage is applied.
Is to displace the tip of the in the direction of arrow (A),
Together with this and the displacement in the y-axis direction, it is freely operated in the x- and y-axis directions. FIG. 7 shows that the piezoelectric element micro-positioning mechanism configured as described above is incorporated in the tunnel unit of the scanning tunneling microscope. In FIG. 7, the box 73
A sample table 72 made of an insulating material for attaching the sample 71 is fixed to the box body 73, and the box body 73 has the sample 71 and the tip 5 of the detection probe.
A feed mechanism 74 as a rough positioning mechanism for bringing a tunnel current closer to a distance of several 10 Å between them, for example, a precision micrometer is attached. The piezoelectric element micro-positioning mechanism 11 of the present invention is attached to the tip of the feeding mechanism 74 via a joint 75. It was confirmed that the piezoelectric element micro-positioning mechanism of the present invention incorporated in such a system is useful as a micro-positioning mechanism for a scanning tunneling microscope.

Further, the three-dimensional piezoelectric element micro-positioning mechanism as shown in the previous embodiment can be used for one-dimensional operation or three-dimensional operation by changing the electrode configuration as shown in FIG.

In FIG. 8, there is a two-dimensional piezoelectric element micro-positioning mechanism 11a on the sample 5 side via a sample table 82 which is a joint edge material. This piezoelectric element micro-positioning mechanism 11a has electrodes x ₁ , x ₂ , y ₁ ,
y ₂ is a quadrangular prism type having a common electrode GND on the inner circumference, and the sample 71 is moved in the direction orthogonal to the detection probe 5 at the opposite position, that is, in the plane (x, y axes). , A square column type one-dimensional piezoelectric element micro-positioning mechanism having an electrode z on the outer peripheral portion on the detection probe 5 side and a common electrode GND on the inner peripheral portion
11b is provided so that the sample 71 can be operated in the vertical direction (z-axis).

As a second embodiment, FIG. 4 shows a piezoelectric element body 1a for three-dimensional operation.
Indicates. Here, the piezoelectric element body 1a has a circular shape in order to make the processing of the inner portion easier than that of the first embodiment. As a result, the inner circumference is formed by boring, and the others are the first
The structure as a minute positioning mechanism and the electrode structure which are the same as those in the embodiment are the same as those shown in the first embodiment.

FIG. 5 shows a piezoelectric element body 1b for three-dimensional operation as a third embodiment.
Indicates. Here, the piezoelectric element body 1b is chamfered at the corner portion 21, and by chamfering the corner portion 21, the joint edge portion, that is, the non-moving portion of the x, y-axis operation electrode is reduced, and the operation is performed in the first embodiment. It is easier than the one shown in. Also, if the corners are not chamfered, the thickness between the inner and outer surfaces of the piezoelectric element becomes maximum at this portion,
When the bending deformation of the entire piezoelectric element is attempted by expanding and contracting the side electrodes facing each other, the rigidity of this corner portion increases, so that it has the meaning of reducing the rigidity and facilitating the deformation by chamfering. For example, the central hollow portion is an inner circle having a diameter of 7 mm, and the chamfered portion has a width of 1 mm, and the others are the same as in the first embodiment. The structure as the minute positioning mechanism and the electrode mechanism are the same as those shown in the first embodiment.

As a fourth embodiment, FIG. 6 shows a piezoelectric element body 1c for three-dimensional operation.
Indicates. The piezoelectric element body 1c is provided with a brim portion 22 at an end portion so as to surely perform adhesive fixing. The brim 22
Is a disk shape having a diameter of 15 mm and a thickness of 1 mm, for example, and the other configurations are the same as those shown in the first to third embodiments. And
The structure as the minute positioning mechanism and the electrode structure are the same as those shown in the first embodiment.

In any of the first to fourth embodiments, the inner peripheral portion of the piezoelectric element body may be penetrated, or one end portion of one may be closed.

〔The invention's effect〕

As described above, according to the present invention, at least one pair of electrodes are provided on the inside and the outside of the piezoelectric element body having a tubular outer surface, or a common electrode is provided on one of the inside and the outside. By providing a split electrode on the electrode and enabling up to three-dimensional operation with the electrode configuration, it is small and easy to handle, and high rigidity enables high-speed scanning, which reduces interference between two axes during in-plane scanning. It has become possible to construct a piezoelectric element micro-positioning mechanism that is sufficiently useful for alignment between the sample and the detection probe of the scanning tunneling microscope. Further, the chamfering reduces the joint edge of the square prism, which is a portion where the electrode is not formed, that is, the non-moving portion, and the thickness between the inner and outer surfaces is reduced to reduce the rigidity against deformation, which facilitates the operation. effective.

[Brief description of drawings]

FIG. 1 is a perspective view of the first embodiment of the present invention, and FIG.
3A is a perspective view of the piezoelectric element body for three-dimensional operation used in the embodiment of FIG. 3, FIG. 3A is a development view of the outer arrangement of electrodes of the piezoelectric element body for three-dimensional operation, and FIG. 3B is a piezoelectric element for three-dimensional operation. FIG. 4 is a perspective view of the second embodiment, FIG. 5 is a perspective view of the third embodiment, and FIG. 6 is a perspective view of the fourth embodiment. FIG. 8 is a first schematic view of a tunnel unit incorporating the fine positioning mechanism of the present invention, FIG. 8 is a second schematic view of a tunnel unit incorporating the fine positioning mechanism of the present invention, and FIG. 9 (a). , FIG. 9 (b) is an explanatory view showing the bending operation of the tubular piezoelectric element body. 1,1 ₁ , 1, ₂ , 10, 20, 30, ...... Piezoelectric element body 2 …… Insulation material 3 …… Detection probe base 4 …… Detection probe holder 5 …… Detection probe 6 …… Inner common electrode ( GND) 7a, 7b …… x-axis operation electrode 8a, 8b …… y-axis operation electrode 9 …… z-axis operation electrode 71 …… sample 74 …… feeding mechanism

Front page continuation (72) Kenji Omura, Kenji Omura 6-3-1, Kameido, Koto-ku, Tokyo Seiko Electronics Co., Ltd. Kunio Kobayashi (56) Reference JP 62-117379 (JP, A)

Claims (2)

[Claims] 1. A micro-positioning mechanism for micro-positioning between a detector and a sample, wherein a common electrode is provided inside a piezoelectric element body integrally formed in a quadrangular prism shape, and a band-shaped z-axis operation extending outside is provided. Electrodes and a pair of divided electrodes for operating in the x-axis direction and the y-axis direction on opposite sides of the quadrangular prism, and between the z-axis direction operation electrode and the divided electrodes and the common electrode. A piezoelectric element micro-positioning mechanism characterized in that a detection unit or a sample attached to the tip of the tubular piezoelectric element body is three-dimensionally operated to finely position it by applying a voltage to. 2. The piezoelectric element micro-positioning mechanism according to claim 1, wherein the inside of the quadrangular prism tubular piezoelectric element is a circular hole, and each corner of the outside quadrangular prism is chamfered. .