JPH01129105A - Scanner of scanning tunnel microscope - Google Patents

Abstract

PURPOSE:To constitute a small-sized scanner by causing a sliding displacement for piezo-elements in two axes out of piezo-elements in three axes intersecting perpendicularly to one another, while causing a displacement in the thickness direction for one in the other axis. CONSTITUTION:A main body 11 of a scanner comprises X-axis and Y-axis elements 17 and 18 which are formed of piezo-elements PZTs bonded by a bonding agent, and a Z-axis element 16 which is insulated from these elements and formed of PZTs laminated in a layer and bonded, and a driving voltage is supplied thereto from a terminal board 12 by urethane-coated lead wires. The displacement of the thickness slide direction of the PZT is used for displacements in the directions Y and Z, while the displacement in the thickness direction thereof is used for a displacement in the direction X. A Z-axis element 16 is constructed to be of a lamination type by laminating four PZTs, so as to increase the amount of the displacement in the direction Z.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a scanner for a scanning tunneling microscope (STM).

[Conventional technology]

Generally, when the probe is brought close to the sample to a point where the atoms at the tip of the probe and the electron cloud of the atoms of the sample overlap by about 1 nm, and in this state a voltage is applied between the probe and the sample, a current flows. This current is called tunnel current, and when the voltage is 1 mV, 1
~10 mA.

The magnitude of this tunneling current changes depending on the distance between the sample and the probe, and by measuring the magnitude of the tunneling current, the distance between the sample and the probe can be measured with ultra-precision. If the needle position is known, the surface shape of the sample can be determined. Furthermore, if the probe position is controlled so that the tunneling current is constant, the surface shape of the sample can be similarly measured from the probe position locus.

FIG. 5 is a diagram showing the schematic configuration of such a scanning tunneling microscope, in which 1 is a probe, 2 is a sample, 3 is a three-dimensional actuator, 4 is an XY scanning circuit, 5 is a servo circuit, and 6 is a tunneling current amplifier. , 7 is the battery, 8 is the memory, 9 is the CPU, 1
0 is a display device.

The three-dimensional actuator 3 is constructed by hollowing out one piezoelectric element, and is controlled through the CPU 9 and memory 8.
The probe 1 is moved and scanned in the Y-axis and Y-axis directions by sweeping the voltage applied to the Y-axis and the Y-axis piezoelectric element by the XY scanning circuit 4, and the probe 1 is moved and scanned in the Y-axis and Y-axis direction piezoelectric elements through the servo circuit 5. The tunneling current is controlled to be constant by controlling the voltage for the sample, and the voltage value at that time is read into the CPU and displayed on the display device 10, so that the surface shape of the sample can be observed.

Such a three-dimensional actuator 3 includes a cantilever type actuator in which a piezoelectric element 11 is connected to a tripod type with screws, etc., as shown in FIG. As shown in FIG. 7, a piezoelectric element 11 is also used in which the Y-axis is supported at both ends and the Y-axis is supported at one end.

[Problems to be Solved by the Invention] However, the conventional tri-pot type has a low vibration frequency of 1 to 3 KHz, which makes it impossible to increase the scanning speed. Therefore, there is a problem in that it is easily affected by thermal drift and the like, resulting in a washed-out image. Furthermore, each movement of the Y-axis, Y-axis, and Y-axis affects the other axes, and if you try to reduce the distortion and increase the movement, there is a problem that the device inevitably becomes large.

By the way, in the case of a scanning tunnel microscope, it is difficult to tell which part of the sample is being observed, so a transmission electron microscope (TEM) is used.
) into a TEM or backscattered electron a microscope (REM)
In addition to searching the field of view using a tunneling microscope, it is desired to perform ultra-precise observation using a tunnel microscope. It could not be used in combination with

The present invention is intended to solve the above-mentioned problems. Each axis can independently reduce distortion, high-speed scanning is possible, and it can be incorporated into a TEM holder.
An object of the present invention is to provide a scanner for a scanning tunneling microscope that can simultaneously observe an EM image or a REM image and an STM image.

[Means for solving problems]

For this purpose, the scanner of the scanning tunneling microscope of the present invention is
This is a scanner in which three-axis piezo element elements made of thin plates are bonded and laminated to which a driving voltage is applied so as to be displaced in each of three orthogonal axes directions, and the piezo element elements in two of the three orthogonal axes are slidably displaced. The present invention is characterized in that the other uniaxial piezo element elements are caused to be displaced in the thickness direction.

[Effect]

The present invention adhesively laminates three-axis piezo element elements made of thin plates to which drive voltages are applied so as to be displaced in three orthogonal axes directions. At the same time, the other uniaxial piezo element element is caused to be displaced in the thickness direction, thereby making it possible to generate displacement independently in three axial directions, and to configure the scanner to be extremely small. Can be done.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the scanner of a scanning tunneling microscope according to the present invention, in which (a) is a plan view and (b) is a plan view.
is a vertical side view, FIG. 2C is a horizontal side view, and FIG. 2 is a diagram for explaining biaxial displacement of the scanner. In the figure, 11 is the scanner body, 12 is a terminal board, 13, 14, 15 is an insulating plate, 16 is a Z-axis element, 17 is an X-axis element, 18
1 is a Y-axis element, 19 to 21 are Y-axis, Y-axis, and Y-axis terminals, 22 is a GND terminal, and 23 is a lead wire.

In the figure, the scanner body 11 is a PZ bonded with adhesive.
Y-axis consisting of T, Y-axis elements 17 and 18, P which is insulated from these by an insulating plate 14, laminated in layers and bonded.
Consists of a Z-axis element 16 made of ZT, and a terminal plate 12
Driving voltages are supplied from the urethane-coated lead wires. In the figure, the scanner body 11 and the terminal board 1
Although shown separately from 2, they may be integrated. Then, the displacement in the thickness sliding (slip) direction of PZT is used for the displacement in the Y direction and the Z direction, and the displacement in the thickness direction is used for the displacement in the X direction. In addition, the Z-axis element 16 has 4 PZTs.
They are stacked to form a laminated type, thereby increasing the amount of displacement in the Z direction. A probe (not shown) is attached to the tip of this Z-axis element.

For example, to explain the displacement of the Z axis, as shown in FIG.
The element 16b further undergoes displacement due to misalignment, and the misalignment displacements are sequentially superimposed, and as a result, a large amount of displacement can be obtained at the tip.

In the scanner of the present invention, by making each element extremely thin and bonding them together with a very thin adhesive layer, the natural frequency of the PZT alone is hardly lowered, and the natural frequency of 250 KHz or more can be achieved. You can get numbers. Furthermore, since the movements of each axis are independent of each other, it is possible to obtain displacement without distortion. In addition, each element is as thin as 0.3 mm, and by making the adhesive layer extremely thin, the overall size is approximately 1.6 mm x 3 m x 5 mm.
It can be constructed with a size of approximately u+.

FIG. 3 is a diagram showing a schematic configuration for obtaining a reflected image using a transmission electron microscope incorporating the scanner of the present invention, and FIG. 4 is a diagram showing the trajectory of an electron beam. In the figure, 31 is a holder, 32
is a sample, 33 is a sample fixing table, 34 is an STM scanning unit, 35
is the STM needle, 3G is the objective lens (OL) pole piece,
37 is an optical axis, 38 is a deflector, 38a and 38b are first and second deflectors, and 39 is an objective lens.

The holder 31 is moved by a side entry goniometer (not shown) to set the sample 32 in a predetermined position. Inside this holder 31, a sample 32 is attached to a sample fixing table 33 as shown, an STM scanning section 34 made of a piezo element is housed, and an STM needle 35 is provided facing the sample 31. This STM
As mentioned above, the scanning unit 34 has a width of about 1.6 x 3 am.
Since it is approximately X 5 u, it can be sufficiently stored in the holder 31.

In the above configuration, an electron beam emitted parallel to the sample surface along the optical axis is bent and focused by the forward magnetic field of the objective lens 39 and the deflector 38 installed above the objective lens, and is focused at an angle to the sample surface. The beam is irradiated in the form of a spot and reflected there, passing on the optical axis and forming a reflected image below the objective lens. The reflected image is formed on a photosensitive surface (not shown), and the sample surface is observed. At this time, since the sample surface is parallel to the optical axis, the uneven portion casts a shadow on the electron beam, so that stripes are observed corresponding to the shape. The degree of this unevenness can be determined by driving the STM scanning section 34.
The M scanning meter 35 performs ultra-precise measurement. In this case, as mentioned above, the resolution of STM is at the atomic level, so
Although the permissible vibration amplitude of the STM needle is 0.1 Å or less, in the present invention, the sample and the needle are fixed in one holder, which is extremely advantageous in terms of vibration resistance. Also, ST
When bringing the M probe close to the sample, it can be observed as a TEM image, making it possible to prevent the STM probe from colliding with the sample surface.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to configure a small scanner, so that the STM can be stored in the TEM holder, and the probe can be brought close to the sample while being observed with the TEM. Further, by using TEM and STM together, it becomes possible to observe a TEM image or a REM image and an STM image simultaneously. Furthermore, since the natural frequency of the scanner is increased to enable high-speed scanning, it is possible to observe a 37M image on TV, and since each axis can be independently displaced, scanning with less distortion can be performed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the scanner of a scanning tunneling microscope according to the present invention, FIG. 2 is a diagram for explaining the Z-axis displacement of the scanner, and FIG. 3 is a diagram showing a transmission electron microscope incorporating the scanner of the present invention. Figure 4 shows the schematic configuration of a scanning tunneling microscope; Figure 4 shows the trajectory of an electron beam; Figure 5 shows the schematic configuration of a scanning tunneling microscope; Figures 6 and 7 are conventional ones. FIG. 2 is a diagram showing a tripot type scanner. 11... Scanner body, 12... Terminal board, 13.
14.15... Insulating plate, 16... Z-axis element,
17...X-axis element, 18...Y-axis element, 19-21...k-axis, Y-axis, Z-axis terminals, 22...
...GND terminal, 23...Lead wire. Applicant: JEOL Co., Ltd. Agent Patent attorney: Masanobu Hirukawa (3 others) (c) Purification of drawings Fig. 5, Fig. 6 Fig. 7 Procedures Litigation formalities (method) % formula % 1, Display of case 1988 Patent Application No. 288077 2
, Title of the invention Scanning tunneling microscope scanner 3, Relationship to the amended case Patent applicant address 3-1-2 Musashino, Akishima-shi, Tokyo Name (427) JEOL Ltd. Representative Takeuchi
Takashi 4, Agent 5, Date of amendment order: February 3, 1988 Date of dispatch: February 23, 1988

Claims (2)

[Claims] (1) A scanner in which three-axis piezo element elements made of thin plates are bonded and laminated to which a drive voltage is applied so as to be displaced in three orthogonal axes directions, and the piezo element elements for two of the three orthogonal axes are 1. A scanner for a scanning tunneling microscope, characterized in that a sliding displacement is caused, and another uniaxial piezo element element is caused to be displaced in a thickness direction. (2) A scanner for a scanning tunneling microscope according to claim 1, wherein the piezo element element for at least one of the three orthogonal axes is a stack of two or more piezo elements.