JPH08240600A - Interatomic force microscope - Google Patents

Abstract

PURPOSE: To markedly facilitate an approach of a probe to a surface of a sample without bringing a board having a cantilever into contact with an obstacle. CONSTITUTION: A head 4 to which a cantilever 1 is attached is loaded on a rotary stage 14, then a stage bottom plate 12, X, Y stages 13X, 13Y, the rotary stage 14 and the head 4 are lowered toward a sample by rotating lifting screws 10a, 10b.... The rotary stage 14 is rotated on the stage 13Y by a rotation driving mechanism and the head 4 is integrally rotated around a laser beam axis O. By the rotation, a board K is conveyed to a position where it is not in contact with a projection section D.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an atomic force microscope.

[0002]

2. Description of the Related Art FIG. 1 shows a mechanical structure of a conventional atomic force microscope. In the figure, reference numeral 1 is a cantilever, and a probe 2 is formed at its tip. The cantilever 1
Is attached to a lever holder 3 having a rectangular frame shape via a substrate K. The lever holder 3 is a guide 4 of a head 4.
It is inserted in G. A laser light source 5 is fixed to the center of the upper part of the head 4, and a photodetector body 6 is attached to a position off the center of the upper part. The photodetector body 6 is composed of a fixed base, a movable base, and a photodetection unit, and the photodetection unit is composed of multi-divided sensors, and recognizes a change in the light receiving position from the balance of the amount of light incident on each sensor. It is possible, so-called PSD. The photodetector unit of the photodetector body 6 is moved two-dimensionally along a plane parallel to the surface of the head on which the fixed base is attached by moving the movable base on the fixed base by a driving mechanism (not shown). It can move in any direction. Reference numeral 7 in the drawing denotes a sample, which is placed on the upper surface of the piezoelectric scanning element 8 via a sample mounting base 50 and is provided with a magnet M in the piezoelectric scanning element.
It is fixed by the magnetism of. The piezoelectric scanning element 8 is composed of three piezoelectric elements which are finely moved in the X, Y and Z directions by a signal from a scanning power source, and is fixed to a bottom portion 9B of a base 9. Elevating screws 10a, 10b, 10c screwed to the upper edge and the bottom of the base through the upper edge 9E of the base via a space.
(Not shown) are provided, and the lifting screw is moved up and down by turning the branch 10B provided in the middle portion of the lifting screw in the space. The lifting screw 1
Steel balls 11 are fitted into the tips of 0a, 10b, 10c ... And a stage bottom plate 12 is placed on the steel balls. On the stage bottom plate, the X, Y stage 13
X and 13Y are mounted, and the head 4 is mounted on the Y stage 13Y. Each of the X and Y stages is driven by a respective drive mechanism (not shown) so that the stage bottom plate 12
It is configured to move upward in the X and Y directions. The X, Y stages 13X, 13Y and the lifting screw 10a,
Reference numerals 10b, 10c (not shown) are coarse movement mechanisms, in which the lifting screw acts on the probe 2 formed on the cantilever 1 by the atomic force of the surface of the sample 7. It is for getting closer to the area. Incidentally, S is, for example,
An elastic body such as a spring, one end of which is the upper edge 9E of the base.
The other end is attached between the stage bottom plates 11. The atomic force microscope having such a structure operates as follows.

From the state shown in FIG. 1, by rotating the lifting screw 10, the stage bottom plate 12, the X, Y stage 13X,
13Y and the head 4 are integrally lowered to the sample side, and the probe 2 formed at the tip of the cantilever 1 is brought closer to the sample 7 to a distance of 1 nanometer or less. Then, an atomic force acts between the atom at the tip of the probe and the surface atom of the sample, and the cantilever 1 bends. At this time, laser light is emitted from the laser light source 5 to the back surface of the cantilever 1 (the surface opposite to the surface on which the probe 2 is formed), and the photodetector 6 changes the incident position of the laser reflected light. To be detected. In the atomic force microscope, the change in the detected incident position of the reflected light corresponds to the bending of the cantilever 1, and this bending is constant, that is, the distance between the probe 2 and the sample 7 is kept constant. While the piezoelectric scanning element 8 is expanded and contracted in the Z direction so as to lean, the probe 2 of the cantilever 1 is scanned in the X and Y directions with respect to the sample 7, thereby obtaining the image of the unevenness of the sample surface. .

[0004]

As described above, the deflection of the lever 1 is detected by detecting the change in the incident position of the laser reflected light by the photodetector 6 based on the principle of the optical lever. An optical system including a laser light source 5, a cantilever 1 and a photodetector 6 is usually fixed inside the head. As shown in FIG. 2, the cantilever, which is a component of this optical system, is formed at the end portion of a substrate K such as a glass substrate or a semiconductor substrate, and this substrate has a width of 2 mm, for example, in consideration of handling. The length is about 3 to 4 mm. The length of the cantilever 1 is about 100 μm from the end of the substrate. Substrate K of this cantilever 1
As shown in FIG. 3, the cantilever 1 is attached to a rectangular frame-shaped lever holder 3 and inserted into the optical path. At this time, since the optical lever system is used, the cantilever 1 is not attached to the sample surface. It is attached so that it has an angle.
At this point, the approach of the probe 2 and the sample 7 is performed by lowering the head 4 to the sample side.
If there is a large convex portion D (obstacle) around the observation position of the sample 7 (the position where the probe 2 at the tip of the cantilever 1 approaches the sample 7), the substrate K is located on the convex portion D first. It comes into contact, and the probe 2 cannot approach the sample surface. At this time, if the fixing angle of the substrate K with respect to the lever holder 3 is increased, the tip of the probe will not face the sample, and the resolution of the obtained atomic force image will be significantly reduced. It is also conceivable to remove the head 4 and remount the sample 7 in a direction that does not hinder the approach, but the convex portion D is located around 100 μm around the observation position and has a height of about 50 μm to 100 μm. Since it is difficult to confirm with the naked eye, the attachment correction operation must be extremely troublesome even when using the optical microscope.

The present invention has been made to solve such problems, and an object thereof is to provide a novel atomic force microscope.

[0006]

Means for Solving the Problem A first invention is to detect a cantilever having a probe formed at its tip, a light source for irradiating the cantilever with light, and a positional deviation of light reflected by the cantilever. And a hollow X, Y on which a hollow rotary stage is mounted.
The rotary stage includes a base provided with a stage and a fine movement mechanism for placing the sample and moving the probe three-dimensionally within a region where an atomic force acts on the sample surface. It is an atomic force microscope in which the head is mounted on the rotary stage so that the center of rotation and the optical axis of the light beam from the light source coincide with each other.

A second invention is a cantilever holder having a cantilever having a probe formed at its tip, a light source for irradiating the cantilever with light, and a positional deviation of light reflected by the cantilever. A head provided with a photodetector, and hollow X and Y stages, and a fine movement for mounting a sample and for moving the probe three-dimensionally within the region of the sample surface on which the atomic force acts. Atomic force microscope comprising a base provided with a mechanism, the head being mounted on the X and Y stages, wherein the cantilever and the photodetector are integrally rotatable. It is a force microscope.

According to a third aspect of the present invention, a fixed head rotatably provided with a cantilever holder having a cantilever having a probe formed at its tip, a light source for irradiating the cantilever with light, and a reflection by the cantilever. A rotary head provided with a photodetector for detecting the positional deviation of the light, a hollow X, Y stage, and a probe on which the sample is placed and in which the atomic force acts on the sample surface. A base provided with a fine movement mechanism for three-dimensional movement,
An atomic force microscope in which the head is mounted on the X and Y stages, wherein the cantilever holder and the photodetector rotate so that the optical detector rotates about an optical axis of a light beam from the light source. It is an atomic force microscope in which the rotary head is integrated.

A fourth invention comprises a cantilever having a probe formed at its tip, a light source for irradiating the cantilever with light, and a photodetector for detecting the positional deviation of the light reflected by the cantilever. Provided head and hollow X,
A base provided with a Y stage and a fine movement mechanism for mounting the sample mount and moving the probe three-dimensionally within the region where the atomic force acts on the sample surface,
An atomic force microscope in which the head is mounted on a Y stage, and a sample mount is mounted on the fine movement mechanism via a piezo motor.

[0010]

[Operation] After the head incorporating the cantilever is placed on the rotary stage, the lifting screw is turned to rotate the stage bottom plate,
The X, Y stage, rotary stage and head are lowered to the sample side. At this time, the rotary stage is rotated on the Y stage in advance, and the head is also integrally rotated with the laser optical axis as a center to bring the substrate to a position where it does not contact the convex portion.

[0011]

[Embodiment] FIG. 4 shows an embodiment of the present invention, in which the same numbers and symbols as in FIG. 1 are the same components. Reference numeral 14 in the figure denotes a rotary stage mounted on the Y stage 13Y, and the head 4 is mounted on the rotary stage. The rotary stage is configured to rotate on the Y stage 13Y by a rotary drive mechanism (not shown).

In the atomic force microscope having such a structure,
Rotating stage 1 with head 4 incorporating cantilever 1
After mounting on 4, the lifting screws 10a, 10b, 10c
(Not shown) By turning the stage bottom plate 12,
The X, Y stages 13X, 13Y, the rotary tage 14, and the head 4 are integrally lowered to the sample side. At this time, for example, when a convex portion D (obstacle) is found on the sample surface by an optical microscope and the head 4 is lowered as it is, the substrate K of the cantilever 1 may come into contact with the convex portion in advance, The rotary stage 14 is rotated on the Y stage 13Y by a rotary drive mechanism (not shown), and the head 4 is also rotated about the laser optical axis O as a unit. By the rotation, the substrate K is brought to a position where it does not contact the convex portion D. For example, as shown in FIG. 4B, the rotary stage 14 is rotated and the head 4 is rotationally moved from the broken line to the solid line. With such an operation, the head 4 rotates around the tip of the probe 2 while maintaining the positional relationship of the optical system (including the laser light source 5, the cantilever 1, and the photodetector 6), so that the observation position does not change. Further, it is possible to avoid contact with an obstacle (projection D).
Since the scanning range of the atomic force microscope is extremely narrow, the substrate does not hit an obstacle that was once avoided in the scanning range. In this state, the lifting screws 10a, 10b, 1
0c (not shown) ... is turned to bring the probe 2 formed at the tip of the cantilever 1 closer to the sample 7 to a distance of 1 nanometer or less, and to make the sample surface uneven as described in FIG. Get as an image.

FIG. 5 shows another embodiment of the present invention, in which only the main part is shown. In the figure, the same numbers and symbols as in FIG. 1 are the same components. In this embodiment, the head 40 is mounted directly on the Y stage 13Y without mounting the rotary stage. The head is composed of an outer cylinder 40A and an inner cylinder 40B, and the inner cylinder 40B is rotatable with respect to the outer cylinder 40A. This inner cylinder 4
A laser light source 5 is fixed to the center of the upper part of 0B, and a photodetector body 6 is attached to a position off the center of the upper part. A disk-shaped lever holder 30 is rotatably fitted and inserted into the head outer cylinder 40A by a rotation drive mechanism (not shown). Reference numeral 31 is a guide for the lever holder. A pin 20 is provided on the lever holder 30, and when the lever holder 30 is fitted into the head outer cylinder 40A, the pin engages with the groove 19 of the head inner cylinder 40B. Therefore, the head inner cylinder 40B is integrated with the lever holder 30 and can rotate with respect to the head outer cylinder 40A.

In the atomic force microscope having such a structure,
The head 40 incorporating the cantilever 1 is attached to the Y stage 1
After mounting on 3Y, lifting screws 10a, 10b, 10c
(Not shown), by turning the stage bottom plate 1
2. The X, Y stages 13X, 13Y and the head 40 are lowered to the sample side. At this time, if there is a convex portion D on the surface of the sample and the substrate K of the cantilever 1 may come into contact with the convex portion if the head 40 is lowered as it is, the lever holder 30 is previously rotated by a rotation driving mechanism (not shown). No.) to rotate. By the rotation, the head inner cylinder 40B also rotates around the laser optical axis O together with the lever holder 30. By the rotation, the substrate K is brought to a position where it does not contact the convex portion D. For example, as shown in FIG. 6, by rotating the lever holder 30, the guide inner cylinder 40B is rotated.
Is rotated, for example, by 90 degrees. By such operation,
Since the head 40 rotates around the tip of the probe 2 while maintaining the positional relationship of the optical system (consisting of the laser light source 5, the cantilever 1, and the photodetector 6), the obstacle (the convex portion) does not change the observation position. It is possible to avoid contact with D). In this state, the lifting screws 10a, 10a
Rotate b, 10c, ... to bring the probe 2 formed at the tip of the cantilever 1 closer to the sample 7 to a distance of 1 nanometer or less, and as shown in FIG. Get as. FIG. 7 shows another embodiment of the present invention, showing only the main part, which is a slight modification of the embodiment of FIG. In this embodiment, a truncated cone-shaped rotating body 2 is provided in a conventional rectangular frame-shaped lever holder 3 '.
1 is fitted, and the cantilever 1 is attached to this rotating body so that its tip is on the laser optical axis. Further, a gear is cut on the side edge of the rotary body 21, and the rotary body is configured to rotate by turning the knob 22 at the side edge. In this embodiment, the pin 20 is provided on the rotating body, and when the lever holder 3'is fitted into the head outer cylinder 40A, the pin is inserted into the head inner cylinder 40B.
Engage with the groove. Therefore, the head inner cylinder 40B can be rotated with respect to the head outer cylinder 40A integrally with the lever holder 3 '. Therefore, when the knob 22 is turned, the head inner cylinder 40B is rotated integrally with the rotating body 21 about the laser optical axis O, and the positional relationship of the optical system (consisting of the laser light source 5, the cantilever 1, and the photodetector 6). Since the head 40 rotates around the tip of the probe 2 while maintaining the above condition, it is possible to avoid contact with the obstacle (projection D) without changing the observation position.

In each of the above embodiments, the head side, that is, the substrate K side on which the cantilever is formed, is rotated, but the sample side may be rotated. However, when the approach position between the probe and the sample is deviated from the center of the sample, if the sample is rotated with respect to the center, the observation position shifts. Therefore, when the sample side is rotated, the sample is rotated and then the observation position is followed by the X and Y stages. FIG. 8 shows an example of a mechanism for rotating the sample. A piezoelectric motor 23 is provided on the upper surface of the piezoelectric scanning element 8, and the sample mount 5 is mounted thereon.
The sample 7 is placed via 0. The piezo motor is configured such that a plurality of piezo elements are attached in a donut shape and individually expanded or contracted or shear deformed, for example, by sequentially deforming the piezo elements one by one, thereby rotating the mounted sample stage and sample. It is a thing.

Further, in each of the above embodiments, from the laser light source,
Although the laser light is directly incident on the sample surface, the laser light source is arranged horizontally with respect to the sample surface, and the laser light from the light source is vertically emitted to the sample surface through the reflecting mirror. May be.

Further, in each of the above-mentioned embodiments, the laser light from the laser light source is made to enter the sample surface perpendicularly, but it may be made to enter the sample surface obliquely. However,
In this case, it is necessary to rotate the substrate having the cantilever and the optical system with respect to the axis perpendicular to the sample surface and penetrating the probe.

Furthermore, in each of the above-mentioned embodiments, the head side or the sample side is rotated by an arbitrary angle, but in order to avoid contact with an obstacle (projection D), it has a cantilever of at least 90 degrees. Since it suffices to rotate the substrate, the lever holder supporting the substrate is simply rotated 90 degrees from the reference position, and the laser reflected light is detected by another photodetector at this position. Is also good.

[0019]

According to the present invention, the probe is approached to the sample surface without changing the observation position of the probe formed on the cantilever so that the substrate on which the cantilever is attached does not come into contact with the obstacle. Is very easily possible.

[Brief description of drawings]

FIG. 1 shows an example of the outline of a conventional atomic force microscope.

FIG. 2 shows an example of a part of a conventional atomic force microscope.

FIG. 3 shows an example of a part of a conventional atomic force microscope.

FIG. 4 shows an embodiment of the present invention.

FIG. 5 shows another embodiment of the present invention.

FIG. 6 shows another embodiment of the present invention.

FIG. 7 shows another embodiment of the present invention.

FIG. 8 shows another embodiment of the present invention.

[Explanation of symbols]

 1 cantilever 2 probe 3, 3'lever holder 4 head 4G guide 5 laser light source 6 photodetector body 7 sample 8 piezoelectric scanning device 9 base 9B bottom 9E upper edge 10a, 10b, ... elevator screw 10B branch 11 steel Sphere 12 Stage bottom plate 13X X stage 13Y Y stage 14 Rotating stage 19 Groove 20 Pin 21 Rotating body 22 Knob 23 Piezo motor 30 Disc-shaped lever holder 31 Guide 40 Head 40A Outer cylinder 40B Inner cylinder 50 Sample mount M Magnet S Elastic body K substrate D Obstacle (projection)

Claims (4)

[Claims] 1. A head provided with a cantilever having a probe formed at its tip, a light source for irradiating the cantilever with light, and a photodetector for detecting a positional deviation of the light reflected by the cantilever. And a hollow X, Y stage on which a hollow rotary stage is mounted, and a fine movement mechanism for mounting a sample and moving the probe three-dimensionally within a region of the surface of the sample where an atomic force acts. An atomic force microscope comprising a base provided with and the head mounted on the rotary stage. 2. A cantilever holder having a cantilever having a probe formed at its tip, a light source for irradiating the cantilever with light, and a photodetector for detecting a positional deviation of the light reflected by the cantilever. And a hollow X, Y stage, and a fine movement mechanism for placing the sample and moving the probe three-dimensionally within the region of the sample surface on which the atomic force acts. An atomic force microscope having a base and having the head mounted on the X and Y stages, wherein the cantilever holder and the photodetector are integrally rotatable. 3. A fixed head rotatably provided with a cantilever holder having a cantilever having a probe formed at its tip, a light source for irradiating the cantilever with light, and a positional deviation of the light reflected by the cantilever. And a rotary head provided with a photodetector for detecting
The X and Y stages include a base provided with a Y stage and a fine movement mechanism for placing the sample and moving the probe three-dimensionally within a region of the sample surface where an atomic force acts. An atomic force microscope in which the head is mounted on the cantilever holder and the photodetector are integrated so that the cantilever holder and the photodetector rotate about an optical axis of a light beam from the light source. Atomized atomic force microscope. 4. A head provided with a cantilever having a probe formed at its tip, a light source for irradiating the cantilever with light, and a photodetector for detecting positional deviation of light reflected by the cantilever. And a hollow X, Y stage, and a base provided with a sample mount and a fine movement mechanism for moving the probe three-dimensionally within the region of the sample surface on which the atomic force acts. In the atomic force microscope having the head mounted on the X and Y stages,
An atomic force microscope in which a sample mount is mounted on the fine movement mechanism via a piezo motor.