JP2937558B2 - Positioning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning probe microscope such as a scanning tunneling microscope and an atomic force microscope, and a positioning apparatus used for an application thereof.

[0002]

2. Description of the Related Art A scanning tunneling microscope (STM) has been rapidly developed in recent years as an apparatus capable of observing the structure of a material surface at a resolution of the order of atoms. First, the measurement principle of the scanning tunnel microscope will be described.

A very sharp and sharp metal probe is brought close to the surface of a sample to be measured to a distance of about 10 angstroms, and a bias voltage of 10 mV to 2 V is applied between the sample and the probe. Electric current flows. Since this current is very sensitive to the distance between the sample and the probe, this distance can be kept constant using feedback control. On the other hand, the probe is attached to an actuator composed of a piezo element that moves slightly in three axial directions, and a voltage applied for feedback control in the Z direction during raster scan in the XY directions represents irregularities on the surface.

The technology of such a scanning tunnel microscope is as follows.
Atomic force microscope (AFM), near-field optical microscope (NF
OM) and other peripheral technologies such as ultra-fine processing machines that enable manipulation of atoms and molecules.
These techniques have in common that the probe is brought close to the sample surface and traced at a distance on the order of atoms, and these are collectively referred to as a near-field microscope (NFM) or a scanning probe microscope (SPM) in an observation apparatus.

The present invention relates to a positioning device used for these devices. In order to trace the probe at a distance on the order of atoms, it is necessary to first thoroughly remove mechanical vibrations that affect fluctuations in the distance. Therefore, these positioning devices also need to be considered from this viewpoint. Further, in order to utilize a scanning tunneling microscope for analysis of a semiconductor element, analysis of a superlattice quantum effect device, and the like, a positioning mechanism for finding a specific portion of a sample is required. Further, a fine processing machine using the scanning tunneling microscope technique requires a positioning device capable of controlling the XY position coordinates with high accuracy.

As an example of a simple positioning function for a scanning tunnel microscope used in the atmosphere, a specific positioning device is not provided, and the scanning is performed while observing the sample and the scanning probe from a diagonal direction with a microscope. Some manually move the probe head with the probe attached. Further, as an example of a positioning device for a scanning tunnel microscope which is used in a vacuum, a sample and a scanning probe are positioned obliquely by a scanning electron microscope (SEM) while a sample is positioned by a worm drive. There is something.

[0007]

However, as long as the mechanical vibration cannot be completely eliminated, no matter how high the accuracy of the mechanism for absolutely positioning the XY position coordinates, it is not sufficient for accurate positioning. .

Therefore, in these conventional scanning tunneling microscopes, since the scanning probe is traced at a distance in the order of atoms, there is a need to thoroughly remove mechanical vibrations that affect the fluctuation of the distance, so that there are limitations on the mechanism. It has been difficult to provide a function of absolutely positioning the XY position coordinates. Actually, in these conventional examples, the function of absolutely positioning the XY position coordinates with high accuracy is not provided.

The present invention has been made in view of the above problems, and solves the above problems so that the scanning probe has high mechanical stability during scanning.
Accordingly, it is an object of the present invention to provide a scanning probe microscope and a positioning device for an application device thereof, which enable absolute positioning of XY position coordinates with ultra-high accuracy.

[0010]

In order to achieve the above object, a positioning device according to the present invention comprises a housing for a probe head having a probe and a flat sample provided below the housing for the probe head. A table having a surface, and a housing of the probe head having three point contact legs at a lower portion thereof, which point-contact and abut on a flat sample on the table surface, and the probe head Is connected to the X and Y via a thin plate spring arranged in parallel with the flat sample surface.
This is a positioning device for positioning the probe head with respect to the sample with the flat sample surface connected to the moving means for moving in the direction as a sliding surface.

[0011] A positioning apparatus according to a second aspect of the present invention includes a probe head housing having a probe;
A table provided below the housing of the probe head and provided with a flat plate having a contact plane for fixing a sample and abutting three point contact legs provided at a lower portion of the housing of the probe head. And, the housing of the probe head is connected to the housing through a thin plate spring arranged in parallel with the contact plane of the flat plate.
This is a positioning device for positioning the probe head with respect to the sample using the flat contacting surface of the flat plate connected to the moving means for moving in the Y direction as a sliding surface.

In the positioning device according to the first or second aspect of the present invention, it is preferable that the thin plate spring is provided symmetrically with respect to the probe Z axis of the probe head.
In the positioning device according to the first or second aspect of the present invention, it is preferable that the thin plate spring is a thin plate spring to which a vibration damping material is attached.

[0013]

The positioning apparatus according to the present invention comprises a housing of a probe head having a probe, and a table provided below the housing of the probe head and having a surface for fixing a flat sample. Is provided with three point contact legs at its lower portion for point contact with and abutting on the flat sample on the table surface, and
The probe head housing is connected to moving means for moving the housing in the X and Y directions via a thin plate spring arranged in parallel with the flat sample surface, and the flat sample surface is used as a sliding surface. Because the positioning device is used to position the probe head relative to the sample, the mechanism that affects the distance variation between the probe and the sample when the probe head housing makes mechanical contact with the sample by three-point contact. The whole resonance frequency can be configured to be extremely high, that is, it is possible to realize sufficiently stable atomic order probe scanning. Further, the thin plate spring connected to the probe head does not alienate the stable three-point contact that enables the above-mentioned mechanical contact.
The probe head can be fixed with high rigidity in the direction. Therefore, the sample can be easily and accurately positioned with respect to the probe by the absolute positioning mechanism. Furthermore, according to the configuration of the present invention, the surface of the flat sample is used as a sliding surface, and a mechanical high-pass filter having a cutoff frequency of approximately the distance between the three-point contact legs is configured. Positioning along with the undulation of the sample, in which the influence of the undulation is removed, is possible.

A positioning device according to a second aspect of the present invention includes a probe head housing having a probe;
A table provided below the housing of the probe head and provided with a flat plate having a contact plane for fixing a sample and abutting three point contact legs provided at a lower portion of the housing of the probe head. And, the housing of the probe head is connected to the housing through a thin plate spring arranged in parallel with the contact plane of the flat plate.
Because the positioning device for positioning the probe head with respect to the sample with the contact plane of the flat plate connected to the moving means for moving in the Y direction as a sliding surface,
Since the housing of the probe head makes mechanical contact with the abutment plane of the flat plate by three-point contact, the resonance frequency of the whole mechanism which affects the variation in the distance between the probe and the sample can be made extremely high, A sufficiently stable atomic atom
It becomes possible to realize the probe scanning of the Dar. Furthermore, the probe head can be fixed with high rigidity in the X and Y directions at rest, without alienating the stable three-point contact that enables the above-described mechanical contact by the thin plate spring coupled to the probe head. Therefore, the sample can be easily and accurately positioned with respect to the probe by the absolute positioning mechanism. Further, according to the configuration of the present invention, since the three point contact legs do not directly contact the sample surface, there is no risk of damaging the sample surface, and the entire range of the sample can be observed.

In the positioning device according to the first or second aspect of the present invention, the thin plate spring is provided with a probe Z of the probe head.
By adopting a preferable mode provided symmetrically with respect to the axis, a change in position in the X and Y directions due to thermal drift (drift due to thermal expansion of a component member) can be minimized, which is preferable.

In the positioning device according to the first or second aspect of the present invention, the thin leaf spring is preferably a thin leaf spring to which a vibration damping material is bonded, so that the thin leaf spring itself can resonate in the XY directions. This is preferable because position fluctuation can be minimized.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A positioning device according to one embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 and FIG. 2 are a perspective view and a sectional view of a positioning device showing one embodiment of the present invention. In FIG. 1, each component is shown in a partially cutaway perspective view with a partial cross section in order to display each component with good visibility. FIG. 3 is a plan view of the probe head viewed from the AA 'direction.

In this embodiment, a scanning tunneling microscope (ST)
M) and an example of a positioning device for a processing device utilizing the STM principle. Table 3 mounted on base 14
A flat sample 4 serving as a sample, for example, a Si wafer, G
aAs wafer is fixed.

Table 3 is used in a system used in the atmosphere.
The sample wafer can be easily fixed by vacuum suction on the top. In a system used in a vacuum, the wafer
Is mechanically clamped around.

The probe head of this embodiment has the following configuration. That is, a coarse insect type driving device (inch worm driving device) 7 composed of a cylindrical movable shaft 5 and a cylindrical fixed shaft 6 is used for the Z axis coarse movement, and the X axis and the Y axis are used.
A cylindrical (tube type) scanner 8 capable of scanning the axis and finely moving the Z axis is mounted, and an STM probe 9 serving as a scanning probe is mounted at the tip of the tube scanner.

A commercial product using a PZT piezoelectric body (lead zirconate titanate piezoelectric body) as a piezo element was used for both the inch worm and the tube scanner. The STM probe has a W (tungsten) needle sharpened by electric field polishing and a PtIr (platinum.
(Iridium) needle or the like is used.

The housing 10 of the probe head has an axially symmetric structure having a substantially cylindrical outer shape, and a fixed shaft 6 of an inchworm is fixed to the center of the shaft. Further, three steel balls are provided on the legs of the housing 10 and three point contact legs 1 are provided.
1 and a probe head 12 is constituted by these members 5 to 11.

The probe head 12 is mounted on the surface of the flat sample 4 by the three point contact legs 11, and is a thin plate spring which is axisymmetric in four directions with respect to the probe Z axis of the probe head. A thin plate spring 13 arranged parallel to the sample surface of the sample 4 is fixed to the housing 10, and the other end of the thin plate spring 13 is fixed to the drive ring 15 by a fixing plate 16 and a mounting screw 17. Drive ring 15
Is mounted on a base 14 via an X-axis drive unit 1 and a Y-axis drive unit 2. By moving the drive ring 15 with these, the probe head is driven via a thin plate spring.

The X-axis drive unit 1 comprises an upper member 20 and a lower member 21. The upper member 20 has a rail 22 having a V-shaped groove, and the lower member 21 has a similar V-shaped cross section. A steel ball 24 is inserted between the rails 22 and 23 so that the upper member 20 and the lower member 21 can slide in the X-axis direction in parallel with each other. . On the upper surface of the upper member 20,
The drive ring 15 is fixed, and the lower member 21 is an upper member 2 of the Y-axis drive unit 2 described below.
5 is fixed.

Similarly, the Y-axis drive unit 2 also includes an upper member 25 and a lower member 26. The upper member 25 has a rail 27 having a V-shaped groove. A rail 28 having a groove having a V-shaped cross section is provided. A steel ball 29 is inserted between the rails 27 and 28, and the upper member 25 and the lower member 26 are parallel to each other.
It can slide in the axial direction. Further, the lower member 26 is fixed to the base 14. By moving the drive ring 15 with these, the probe head is driven via the thin plate spring. Note that the X-axis drive unit and the Y-axis drive unit are not limited to those described above, and it is a matter of course that other known units can be applied as long as they have high accuracy. Steel ball 2
Instead of 4 or 29, a plurality of roller-shaped bearings are arranged in an X-shape with each other, and rail grooves having a shape adapted to the grooves are used. May be changed.

The thin plate spring 13 is made of stainless steel or has a low thermal expansion coefficient of Invar (Fe64% -Ni36%).
The thickness is 0.05 to 0.3 mm, and they are arranged as axially symmetric as possible. The sample 4 is attached and detached by removing the mounting screw 17 of the thin plate spring 13.

As described above, the constraint of the moving body (probe head) by the combination of the three-point contact leg of the present invention and the thin plate spring is as follows.
Advantageously, the scanning probe microscope and its application apparatus are as follows. That is, when the probe head is not restrained at all, the translational motion in three directions of XYZ and XYZ
Although there are a total of six degrees of freedom of rotational motion about the axis, when the sample plane and the probe head are brought into contact with three points, three degrees of freedom of rotation of the sample plane around the XY directions and the Z axis remain. The rest of the movement is restrained. By the way, a flat thin plate spring bends easily in the thickness direction, but has extremely high rigidity in the direction in the plane of the flat plate. Therefore, by using this property as a means for restricting the freedom of the above-mentioned movement, without alienating a stable three-point contact,
All degrees of freedom of the probe head can be constrained.

As a result, the probe head can be mechanically coupled at three points very close to the scanning point of the sample, so that the probe head can be configured to have a high resonance frequency and the irregularities of the atomic order can be traced stably. High anti-vibration effect, which is indispensable for Generally, in order to realize the Z-axis control of the atomic order, it is necessary to set the atomic order of 1 angstrom to 0.01.
It is necessary to suppress the mechanical vibration to Angstrom or less. For example, in a configuration in which the probe head is floated on the sample surface without using three point contact legs and is directly mounted on the base via the XY drive unit, The rigidity of the portion corresponding to the weak point of the entire device, such as the reduction in rigidity due to the structure and the effect of the rigidity of the XY drive unit, is effective, leading to a reduction in the resonance frequency.

On the other hand, according to the configuration of the present invention, it is possible to relatively easily obtain the above-described high anti-vibration effect. That is, by configuring the probe head to have a high resonance frequency, the resonance frequency of the system is increased, while such a device as a scanning probe microscope is usually provided on an air spring or other vibration isolating device. The anti-vibration system has a property of cutting a high resonance frequency. Therefore, by increasing the resonance frequency of the device system, a high anti-vibration effect can be obtained by a mutual multiplication effect.

Further, according to the structure of the present invention, since the surface of the flat sample is used as the sliding surface, a mechanical high-pass filter is provided with a cutoff frequency of approximately the distance between the three-point contact legs. Because of the shape, it is possible to eliminate the influence of the undulation of the sample and perform positioning along the undulation of the sample.

FIG. 4 is a sectional view of a positioning apparatus showing another embodiment of the present invention. The numbers and functions of the components are the same as those of the embodiment described with reference to FIGS. In addition, since the plan view of the probe head is the same as that of FIG. 3, illustration and description are omitted.

The difference from the first embodiment is that the three point contact legs 11 provided on the housing 10 of the probe head are provided not on the sample surface 4 but directly on the table 3. The plate 18 is brought into contact with a flat plate 18 having a contact plane, and this is used as a sliding surface. As the flat plate 18 having the contact plane, an optical flat made of quartz or the like is suitable. Although not particularly limited, in the case of this embodiment, the flatness is λ
/ 20 was used.

In this configuration, the distance between the three point contact legs is relatively large as compared with the first embodiment, and the resonance frequency is somewhat reduced by this amount. However, the entire area of the sample surface can be effectively observed. Alternatively, it can be a machined surface. In addition, the positioning can be performed with reference to the contact plane without depending on the flatness of the sample.

Further, in both the first and second embodiments, the thin plate spring connected to the probe head is formed symmetrically with respect to the probe Z axis. XY by drift due to thermal expansion)
The change in position in the direction can be minimized. In addition,
In an actual design example, in addition to the thermal expansion compensation by such a configuration, each member constituting the apparatus, particularly the probe housing 1
0, table 3, XY drive units 1, 2, thin leaf spring 1
The base 3 and the base 14 are made of Invar or another material having a low coefficient of thermal expansion, thereby achieving extremely high thermal stability. .

When the apparatus is used in the atmosphere, the thin plate spring may be affected by acoustic vibrations and may receive slight vibrations in the X and Y directions. By attaching a Viton rubber sheet (approximately 0.5 mm thick) to the front and back sides of the thin plate spring, vibrations that would hinder practical use can be prevented. Although not particularly limited, the thickness of the thin leaf spring 13 is preferably about 0.05 to 0.3 mm, and in the above embodiment, the thickness was 0.25 mm.

In the above embodiment, the XY scanning, the Z-axis fine movement and the coarse movement are performed by the tube type scanner and the inch worm provided on the probe housing side. It should be noted that it is effective to provide all of them on the table side.

The detection of the position of the probe can be performed, for example, by
Since the detection can be performed using a known optical interferometer, the description is omitted here. In the above description, the positioning device mainly applied to the scanning tunneling microscope (STM) and the processing device using the STM has been described. However, various types of observation devices that are derived from the STM and the positioning device for the processing device are effective. Of course.

[0039]

According to the present invention, it is possible to realize a high anti-vibration effect which enables high-resolution probe scanning with a relatively simple structure.
A positioning device applicable to high-precision absolute positioning can be provided.

Further, according to the first positioning device of the present invention, it is possible to perform the positioning while eliminating the influence of the undulation of the sample. Further, according to the second positioning device of the present invention, there is no possibility of damaging the surface of the sample, and the entire range of the sample can be observed.

Further, in the present invention, the thin plate spring is provided to be axially symmetric with respect to the probe Z axis of the probe head, thereby minimizing positional changes in the X and Y directions due to thermal drift. be able to.

Further, in the present invention, by adopting a mode in which the thin leaf spring is a thin leaf spring on which a vibration damping material is stuck, positional fluctuation in the XY directions due to resonance of the thin leaf spring itself can be minimized. .

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a positioning device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a positioning device according to an embodiment of the present invention.

FIG. 3 is a diagram showing a positioning device according to an embodiment of the present invention;
FIG. 3 is a plan view of the probe head as viewed from a direction A ′.

FIG. 4 is a sectional view of a positioning device according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-axis drive unit 2 Y-axis drive unit 3 Table 4 Sample 5 Movable axis 6 Fixed axis 7 Insect driver 8 Cylindrical scanner 9 Probe 10 Probe head housing 11 Point contact leg 12 Probe head 13 Thin plate spring 14 Base 15 Drive Ring 16 Fixing Plate 17 Screw 18 Flat Plate with Contact Plane 20 Upper Member 21 Lower Member 22 Rail 23 Rail 24 Steel Ball 25 Upper Member 26 Lower Member 27 Rail 28 Rail 29 Steel Ball

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ identification symbol FI H01J 37/28 H01J 37/28 Z (58) Field surveyed (Int.Cl. ⁶ , DB name) G01B 21/00-21 / 30 G01B 7/00-7/34 G01N 37/00

Claims (4)

(57) [Claims] 1. A housing for a probe head having a probe, and a table provided below the housing of the probe head and having a surface for fixing a flat sample, wherein the housing of the probe head has a lower part. Point contact with the flat sample on the table surface
And the probe head housing is connected to moving means for moving the housing in the X and Y directions via a thin plate spring arranged in parallel with the flat sample surface. A positioning device for positioning the probe head with respect to the sample using the flat sample surface as a sliding surface. 2. A probe head housing having a probe and three point contact legs provided below the probe head housing for fixing a sample and provided at a lower portion of the probe head housing. And a table provided with a flat plate having an abutting plane for the probe head, and the housing of the probe head is configured to move the housing in the X and Y directions via a thin plate spring disposed in parallel with the abutting plane of the flat plate. A positioning device for positioning the probe head with respect to the sample using the contacting plane of the flat plate, which is connected to a moving means for moving the probe head, as a sliding surface. 3. The positioning device according to claim 1, wherein the thin plate spring is provided symmetrically with respect to the probe Z axis of the probe head. 4. The positioning device according to claim 1, wherein the thin plate spring is a thin plate spring to which a vibration damping material is attached.