JPH032604A - Apparatus for micropositioning - Google Patents

Abstract

PURPOSE:To obtain an apparatus for micropositioning which can withstand external vibration sufficiently and has high regidity by pushing a movable stage for mounting a sample to the reference surface of a fixed stage with a spring, and finely moving the movable stage along the reference surface with a micrometer. CONSTITUTION:A movable block 1 which is a movable stage for mounting a sample 14 for a sanning tunneling microscope 14 is supported by a shaft 5. The block 1 is housed in frames 2 and 3 which are fixed stages. A sliding surface 13 is pushed to the reference surface with a screw 9 and a spring 12. The movable block 1 is pushed to the direction orthogonal to the shaft 5 with a screw 10 and a spring 11. A micrometer head 4 is in contact with the opposite side. When the micrometer 4 is rotated in this constitution, the movable block 1 is displaced with the rotary shaft 5 as the center. The distance between the block 1 and a probe 15 is brought close to about 1 nm. At this time, since a friction lock is employed, sufficient rigidity which can withstand external vibration is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a micropositioning device used in various precision instruments such as a scanning tunneling microscope.

[Prior Art] In recent years, scanning tunneling microscopes having resolution on the order of atoms and molecules have been developed and are being applied to surface structure analysis, surface roughness measurement, and the like.

This scanning tunneling microscope utilizes the fact that a voltage is applied between a conductive sample and a conductive probe, and when the probe is brought close to a distance of about 1 nm, a tunnel current flows, and the tunnel current changes exponentially with the distance. This is what I did. The tip of the probe is polished to a very sharp point by electrolytic polishing, etc., and when it scans two-dimensionally while maintaining a constant distance from the sample surface made of a conductive material, the atomic arrangement of the surface and the shape of the irregularities can be detected. The tunnel current changes and a surface image can be obtained (rSolid State Physics J Vo ρ22, No. 3
1987 PPI 76-186).

Conventionally, devices that require minute positioning on the order of nanometers (nm), such as scanning tunneling microscopes (hereinafter abbreviated as STM), use piezoelectric elements as actuators to control the distance between the sample and the probe. Many devices are in use that have a configuration that allows them to approach each other down to nanometers. IBM Journal Research Development (
Vou30 No. 4 page 356) has X, Y
We are proposing a micro-positioning mechanism using a tribo-νF type actuator consisting only of Z-independent piezoelectric elements.

In addition, as a device other than a piezoelectric element, Japanese Patent Application Laid-Open No. 1987-197
As disclosed in Japanese Patent No. 45, there is a device having a mechanism for pushing a leaf spring with a micrometer. Its configuration is shown in FIG. A sample 33 to be measured is attached to a sample holder 32. The sample holder 32 is provided on the substrate 37 via the member 23 and the plate 20. A tunnel chip 34 constituting a probe is provided on a substrate 37 on the lower surface of the sample 33 via a support 36 .

The sample 33 is finely moved and positioned with respect to the tunnel chip 34 by the micrometer 28.

[Problems to be Solved by the Invention] However, in the conventional micro-positioning using the piezoelectric element as an actuator, the operating performance largely depends on the performance of the piezoelectric element, and the amount of displacement (movement range) is several microns, making it difficult to use the piezoelectric element as an actuator. Even in a laminated structure, the limit is about 10 microns. In addition, in micro-positioning using conventional micrometers and leaf springs, the range of movement can be wide from micro to millimeter order, but leaf springs utilize elastic deformation, have low rigidity, and are not affected by vibration. Since it is easy to use, it cannot be said to be suitable for use in STM, etc. In STM, the distance between the sample and the probe is close to several nanometers, and the influence of external vibrations greatly affects the entire device. Therefore, such vibrations must be avoided as much as possible. When seeking a device that is resistant to external vibrations, a lock may be considered, but from the viewpoint of simplifying the device and improving operability, a mechanism that does not have a complicated lock mechanism and is resistant to external vibrations is desired.

[Means and effects for solving the problem] In the present invention,
In order to solve the above problems, the following technical means were provided.

The positioning means of the present invention is a system in which a movable table having a sliding surface and capable of fixing a sample is pressed and fixed to a reference surface of the fixed table, and the movable table is rotated along the reference surface. That is, according to the present invention, by pressing the movable base against the fixed base, it is possible to increase the rigidity of the movable base and provide a micro-positioning device that is resistant to external vibrations. Further, since there is no limitation on the means for moving the movable base, it is possible to provide a moving means according to the purpose, and the device can be used in a wide range of applications.

[Example] Hereinafter, the configuration of a micro-positioning device and its operating mechanism according to the present invention will be described in detail with reference to the drawings.

FIGS. 1(a) and 1(b) are drawings showing an overall perspective view and an exploded perspective view, respectively, of a micro-positioning device according to the present invention. (a) In the figure, 1 is a movable block that serves as an object to be positioned or a sample stage, 2 and 3 are frames of the movable block, 4 is a micrometer head for moving the movable block, 14 is a sample, and 15 is an STMTM 116. This is a tube-shaped piezoelectric element for displacing the probe 15 in the X, Y, and Z directions. (b) In the figure, 5 is a support rotating shaft that supports the movable block 1 and serves as a bearing, 6 and 7 are bearings, 8 is a bearing support rod of the bearing 7, and 9 and 10 are screws for pressing the movable block 1. , 11 and 12 are springs for pressing the movable block 1, and 13 is a sliding surface on which the movable block 1 and the frame 2 are in contact.

This embodiment is a micro-positioning device for bringing the distance between the STM sample and the probe closer, specifically to the distance 11iff (approximately 1 nanometer) through which a tunnel current flows between the sample and the probe. . Therefore, the sample 14 is mounted on the movable block l, and the probe 1 is mounted on the upper part of the sample 14.
5 and a tube-shaped piezoelectric element 16 for supporting and scanning it. The distance between the probe 15 and the sample 14 is
In advance, the object is approached to a distance of several hundred nanometers while being observed using an optical microscope or the like.

When the micrometer head 4 shown in FIG. 1(a) is rotated, the movable block 1 receives a vertical displacement force about the rotating shaft 5. Strictly speaking, the movable block 1 moves in an arc around the rotation axis 5, but for the purpose of this embodiment, the moving distance is less than 100 nanometers, so the movable block 1 moves in the vertical direction. It can be thought of as performing linear motion.

2 and 3 are a sectional view taken along the line AA and sectional view taken along the line BB in FIG.

In FIG. 2, the movable block 1 is supported by a rotating shaft 5. As shown in FIG. The rotating shaft 5 is attached to the frame 2 by screw 1.
7, it is fixed. Movable block 1 and rotating shaft 5
is guided by a bearing 6, and is configured to reduce friction between the rotary shaft 5 and the movable block 1 and to allow the movable block 1 to rotate smoothly. Further, the contact force between the movable block 1 and the frame 2 can be adjusted by adjusting the strength of the force for pressing the bearing 6 with the press plate 18. As shown in FIG. 1(b), the sliding surfaces 13 of the movable block 1 and the frame 2 are provided at positions where they are pressed by the micrometer 4 when the movable block 1 rotates @b5, and the other parts are pressed by the micrometer 4. , escapes to avoid contact with frame 2. Note that the shape of the sliding surface is not limited to this. This is a means to reduce friction and ensure smooth rotation.

Note that a suppression spring 12 is provided at a position opposite to the sliding surface other than around the rotating shaft 5. The pressing force can be freely adjusted using the screw 9. The bearing 7 is provided so as not to restrict the moving direction of the movable block 1, and is not limited to a bearing in any way. For example, a metal ball may be used.

In FIG. 3, a pressure spring 11 and a pressure adjustment screw 10 are provided at opposing positions sandwiching the micrometer head 4 and movable block 1. The spring elastic force of the spring 11 is set to be more rigid than the frictional force between the movable block l and the frame 2 calculated from the sliding surface area and the contact force.

Rotation @5, distance 11tIt from the pressing position by the micrometer head 4, and rotation axis 5 from the center of the movable block 1.
Distance to 1 lil! Depending on the ratio of S, the reduction or enlargement ratio can be freely set. If I>S, the mechanism becomes a reduction mechanism, and if u<S, it becomes an expansion mechanism. However, rotation axis 5
The radius of is! , S. In this embodiment, a reduction mechanism is used. When a micro-positioning device with the above mechanism was used for STM,
The distance between the sample and the probe was brought close enough to allow tunneling current to flow, and the probe could be held in that position. In addition, during STM positioning, since the distance between the sample 14 and the probe 15 is close to several nanometers, it is necessary to for,
It is necessary to provide electrical feedback to keep the distance between the sample 14 and the probe 15 constant. FIG. 4 shows the positioning device of this embodiment with an electrical block diagram added. In the figure, 41 is a bias voltage for applying a bias voltage to the sample 14, 42 is a tunnel current detection circuit for detecting the tunnel current that flows when the sample 14 and the probe 15 approach to a distance of several nanometers;
43 is a sample/probe distance control circuit for giving feedback to the piezoelectric element 16 so that the distance between the sample 14 and the probe 15 becomes a desired instantaneous movement based on information from the tunnel current detection circuit 42. . In this way, by providing electrical feedback, it is possible to avoid contact between the sample and the tip during the initial approach, and also avoid contact between the sample and the tip when performing drift due to mechanical relaxation or two-dimensional operation. measure. Furthermore, when the probe is two-dimensionally scanned over the sample, a two-dimensional image of the sample 14 can be obtained by monitoring the control signal given by the control circuit 42 to the piezoelectric element with a monitor means (not shown), and it is possible to detect irregularities, etc. . The rotation of the micrometer head for positioning can be done manually or by mechanically applying rotational force using a stepping motor or the like.

Next, other embodiments of the present invention will be described.

A method other than the pressing mechanism using the micrometer head 4 and spring 11 shown in FIG. 3 will be explained using FIG. 4.

This example was used when performing minute positioning on the order of several micrometers. When positive and negative pressures are simultaneously applied to the laminated piezoelectric PZTs 42 and 43, the movable block 1 receives a displacement force. Furthermore, when a voltage is applied to the stacked piezoelectric PZTs 43 and 42 in the opposite polarity to the voltage polarity, that is, negative and positive at the same time,
The movable block receives a displacement force opposite to the displacement direction.

As a result of using the above-mentioned laminated PZT, it was possible to accurately perform minute positioning on the order of several micrometers.

In this specification, "reducing r sensitivity" means reducing the output, which means reducing the ratio of the output to the amount of light received by, for example, lowering the photoelectron amplification factor of the photomultiplier tube. This includes reducing or blocking the received light by inserting a light attenuating means (for example, a filter) into the ml of the reticle, or reducing or blocking the light itself incident on the reticle.

[Effects of the Invention] With the micro-positioning device having the above-described mechanism, a device with high rigidity that can sufficiently withstand external vibrations can be achieved. Accordingly, minute positioning of several tens to hundreds of nanometers can be performed with high accuracy, which has a great effect on improving the reliability of the apparatus. In the present invention, since a friction lock is adopted, it is possible to maintain a stationary state once mechanical relaxation is completed, and at this time, it is possible to operate the device with less vibration and prevent contact between the probe and the sample. Furthermore, it is possible to realize a high-performance, high-rigidity device that does not require a complicated locking mechanism.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are an assembled perspective view and an exploded perspective view of a micro-positioning device embodying the present invention, respectively, and FIG. 2 is a sectional view taken along line AA in FIG. 1(a). , Figure 3 shows the first
FIG. 4 is a block diagram of another embodiment of the present invention, and FIG. 5 is a block diagram of a conventional micro-positioning device. 1; Movable block, 2.3: Frame, 4; Micrometer head, 5; Shaft, 6.7; Bearing, 8: @Reception support rod, q, to; Screw, 11.12. Spring, 13; Sliding surface, 14; Sample, 15: Probe, 16: Tube type piezoelectric element, 42.43: Pressure 1j PZT. (A-A Front Entrance) Diagram Procedure Amendment (Voluntary) November 16, 1989

Claims (6)

[Claims] (1) A fixed member having a reference surface, a movable member having a sliding surface that contacts the reference surface and on which a sample to be positioned is mounted, and the movable member rotatably supporting the movable member with respect to the fixed member. A rotation axis perpendicular to the reference plane, a pressing means for pressing the sliding surface of the movable member toward the reference plane of the fixed member, and a driving means for rotationally moving the movable member about the axis. A micro-positioning device featuring: (2) The driving means presses at least one outer circumferential surface of the movable member perpendicular to the sliding surface, and the sample is mounted on another outer circumferential surface of the movable member. A micro-positioning device according to claim 1. (3) The micro-positioning device according to claim 1, wherein the driving means comprises a micrometer head. (4) The micro-positioning device according to claim 1, wherein the driving means comprises a piezoelectric element. (5) A movable member capable of fixing a sample and having a sliding surface in contact with a reference surface of the fixed member, and the movable member and the fixed member,
A shaft rotatably supported in a direction perpendicular to the reference surface, a mechanism on the shaft for pressing the movable member sliding surface against the reference surface, and a pressing mechanism for rotationally moving the movable member along the reference surface. Micro positioning device. (6) A fixed member having a reference surface, a movable member having a sliding surface that contacts the reference surface and on which a sample to be positioned is mounted, and a movable member facing the sample mounted on the movable member and facing the sample. a probe disposed at a position where a tunneling current can flow between the probes, a means for detecting a tunneling current between the sample mounted on the movable member and the probe, and a sliding portion of the movable member. A micro-positioning device comprising: a pressing means for pressing a surface toward a reference surface of a fixed member; and a driving means for moving a movable member relative to the fixed member.