JPH02203205A - Three-dimensional actuator and scanning type tunnel microscope device - Google Patents

Abstract

PURPOSE:To improve the dynamic range of measurement resolution greatly by grasping the position of a probe, which uses the three-dimensional actuator structured by mounting an optical fiber on a piezoelectric driving element, on the surface of a sample in real time. CONSTITUTION:The probe 6 is mounted by a support base 8 on the cylinder type piezoelectric driving three-dimensional actuator which has piezoelectric elements 1 and 4, 2 and 5, and 3 for an X direction, a Y direction, and a Z direction. An optical fiber cable 7 is also mounted on this base 8 and its tip is directed to the tip end of the probe 6. The cable 7 is formed by bundling ten thousands of glass fibers and serves as an optical guide and a lens is fitted atop; and an image of the surface area of the sample 9 at the tip end part of the probe 6 is formed on an optical system 10 and the state of the measurement area can be grasped on a TV monitor. Thus, the area to be measured is grasped in advance and the scanning area of the probe 6 is secured to follow the procedure for measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a three-dimensional actuator and a scanning tunneling microscope device using the same.

BACKGROUND OF THE INVENTION Conventional three-dimensional actuators are constructed by forming a piezo drive element that expands and contracts in the x, y, and z directions into a cylindrical or tribod shape. FIG. 2 is an example of this, showing a configuration diagram of a cylindrical three-dimensional actuator. x, y, z
Piezo elements 13, 14, 15 and X extending in each direction of
, consisting of piezo elements 1B and 17 extending in the Y direction. For example, in the case of a scanning tunneling microscope (hereinafter abbreviated as STM), a probe 1 is attached to the outer wall of this cylinder.
8 is fixed on a fixed base 1B and brought close to the surface of the sample 20 to within a few nm, and a voltage is applied across the gap to detect the tunnel current flowing through the output resistor 21 and amplify it by the amplifier circuit 22. Feedback is applied in the form of voltage to the piezo element 15 in two directions to keep this tunnel current constant, and in this state X, X, Y, Y,
Piezo element in direction 13. 1B, 14. By performing two-dimensional scanning at 17, topological information on the surface of the sample 20 can be obtained.

The 87M device as described above has an extremely high in-plane resolution of <10 and a vertical resolution of <1, so it has the disadvantage of not being able to obtain macroscopic information.

This drawback is considered to be an essential drawback of STM, and unless important information about the location on the sample surface where the local surface area from which topological information was obtained is obtained, the field of application of STM will be limited. It was said to be quite limited.

The present invention has been devised in view of the above problems.

Problems to be Solved by the Invention The problems to be solved by the present invention are to realize an STM device that can clearly grasp the position being measured by the STM device and has a resolution with a large dynamic range.

Means for Solving the Problems The present invention is an STM device that can grasp the position of a probe tip on a sample surface in real time using a three-dimensional actuator having a structure in which an optical fiber is attached to a piezo drive element.

Effect By implementing the present invention, the dynamic range of resolution, which has been a major problem in the past, has been dramatically increased.
Not only has it become possible to measure the sample surface or in a local area, but it has also become possible to irradiate the measurement area of the sample surface with light of arbitrary intensity.

Example (Example 1) FIG. 1 shows an example of the present invention. As in the prior art, a probe 6 is attached to a cylindrical piezo-driven three-dimensional actuator by a support base 8. The three-dimensional actuator includes piezo elements in the X and X directions. 4. Y, Y
piezo element in the direction 2. Piezo elements 3 in the S and X directions are provided. An optical fiber cable 7 is attached to the support stand 8.
is attached, and the tip of the cable 7 is directed toward the tip of the probe 6. With a voltage of about 1 V applied between the sample 9 and the probe 6, the two are brought close to each other to a distance of about 11 mm, and a tunnel current begins to flow due to the overlap of the wave functions on the surfaces of both materials. The tunnel current is converted into a voltage by the output resistor 11 and output, and is input to the feedback circuit system via the amplifier 12 and the like. At this time, if a current larger than the preset tunnel voltage value of 0.3 nA flows, the feedback circuit reduces the voltage applied to the piezo element 3 in the X direction, and the probe 6 moves away from the surface of the sample 9, causing an exponential The tunnel current decreases. Conversely, when a current smaller than 0.3 nA flows, the system applies feedback so that the probe 6 approaches the surface of the sample 9.

In this state, the piezo elements 1, 4 in the X and X directions. and Y,
A triangular wave voltage is applied to the piezo elements 2 and 3 in the Y direction to scan the plane two-dimensionally. In this example, the scanning range was 5μ1112, and the observation was performed in the atmosphere.

Here, the optical fiber cable 7 has a diameter of 10 to 20μ.
The shoes are made of hundreds of glass fibers tied together and serve as a light guide. Furthermore, the focal length is 411111° and the diameter is 2.
A mm lens is attached to the tip of the optical cable 7, making it possible to project an image of the sample surface area at the tip of the probe. Further, at the terminal end, an optical system including an image sensor (magnification: 1 to 400 times) forms an image on 1G and converts it into an electrical signal, so that the state of the measurement area can be seen on a TV monitor.

Using this device, it was possible to clearly distinguish between the AI wiring area and the 51 board area of the LSI and measure the surface unevenness. Furthermore, when the heat treatment time is increased, titanium silicide material becomes TlSi! A phenomenon in which the surface of the region aggregates into an island shape (about 50 μl in diameter) is observed. Even when this is used as a sample, TiS! □ area and the other 81 substrate areas, and by moving the tip of the probe 6 using the coarse movement mechanism in X and Y, it is possible to distinguish the differences in the surface unevenness of each area. Ta.

Since STM has an extremely high resolution, it is suitable for measurements on a relatively flat surface, but if it scans across an area with large steps, there is a risk that the probe 6 will hit the sample surface. For this reason, it is extremely beneficial to understand the area to be measured in advance, secure a probe scanning area, and then perform the measurement.

The same thing can be said even if the piezo drive element in the embodiment of the present invention is changed from a cylindrical shape to a tri-bod shape.

(Example 2) In Example 1 of the present invention, an example will be shown in which a part of the bundled optical fibers is used as a light guide for a light source. FIG. 3 is a sectional view of the optical cable 7 of FIG. 1. In the figure, the end of the shaded area 27 is connected to a light source, and light is emitted from this light guide area 27. The remaining area 2B is the same as in Example 1, and an optical system 1 including an image sensor captures an optical image of the tip of the probe and the surface of the sample.
This is a light guide area that sends light to G.

By using a laser as a light source, it is possible to understand changes in surface structure due to light irradiation.

(Example 3) In Example 1.2 of the present invention, the probe e and the optical fiber cable 7 were formed of separate objects, but in the case of this example, the optical fiber cable 7 itself is connected to the probe 6. This is the case of the type that also serves the role of

FIG. 4 shows the case of Example 3. In the figure, 5 is the Y-direction piezo element shown in Example 1, 8 is the sample surface, and 8 is a probe support. 2B is the objective lens in Example 1, and has a needle-like protrusion 27 at its tip. 25 is an optical fiber cable. The surfaces of the objective lens 211.27 and the optical fiber cable 25 are coated with platinum.
It doubles as an optical fiber cable and a probe at the same time. here,
The tip of the objective lens 26 is not coated with platinum.

The other systems are the same as in Examples 1 and 2.

In the case of this embodiment, the needle-like protrusion 2 at the tip of the objective lens 2B
7, which has the advantage that the measurement area can be observed in real time with higher accuracy. It is particularly suitable for observing reaction processes in solutions.

Effects of the Invention The present invention makes it possible to significantly improve the dynamic range of measurement resolution, which has been an obstacle in conventional STM, to measure a desired local surface area, and to improve the surface structure based on light irradiation. Measuring changes has become easier.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a three-dimensional actuator part according to the present invention (Embodiment 1), Fig. 2 is a block diagram of a conventional three-dimensional actuator part, and Fig. 3 is a block diagram of an optical fiber cable. The cross-sectional view, FIG. 4, is a configuration diagram of the measuring section in Example 4. 1 to 5... Piezo element, 6... Probe, 7...
・Optical fiber cable, 8... Support stand, 9...
Sample, lO...Optical system. Name of agent: Patent attorney Shigetaka Kurino (1 person)Figure Q Figure

Claims (2)

[Claims] (1) A three-dimensional actuator with an optical fiber attached to a piezo drive element. (2) A scanning tunneling microscope device equipped with a three-dimensional actuator in which an optical fiber is attached to a piezo drive element and capable of recognizing measurement positions.