JPH06137846A - Interatomic force microscope device - Google Patents

Abstract

PURPOSE:To provide an interatomic force microscope device which is low in noise level, high in detection sensitivity, and excellent in resolution. CONSTITUTION:A reflector 3b with a larger diameter than the spot diameter of a laser beam which is oscillated and made incident from a laser beam oscillating source 7 is provided on a canti-lever 3. Then, most laser beam is reflected at a reflected part 3b, the canti-lever 3 is deformed according to the unevenness on the surface of a specimen, the reflection position and reflection angle of the laser beam at the reflected part 3b are varied to change the optical path of the laser beam, and the laser beam is detected by a photo-sensor 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atomic force microscope apparatus for magnifying and recognizing unevenness on a sample surface by utilizing atomic force.

[0002]

2. Description of the Related Art FIG. 14 shows, for example, Applied Phy.
sics Letter 55 (1989), pag
e 2491, FIG. FIG. 3 is a main part configuration diagram showing a conventional atomic force microscope apparatus shown as 1. In the figure, 1 is a sample table for fixing a sample 2, and 3 is a probe 4 which is in contact with the sample 2 via an atomic force at the tip portion, and the tip portion is vertically movable so that both end portions are supported by a support plate 5. A fixed V-shaped cantilever having a base of about 100 μm and a height of about 200 μm, and 6 is an optical system that guides the laser light oscillated from the laser light oscillation source 7 to a reflection portion at the tip of the cantilever 3, and is, for example, a convex lens. Reference numeral 8 is a photo sensor for receiving the laser light reflected by the reflecting portion of the cantilever 3.
9 is provided between the cantilever 3 and the photo sensor 8,
A reflector 10 for changing the optical path of the laser light reflected by the reflecting portion of the cantilever 3 to the photo sensor 8 receives a signal from the photo sensor 8 and controls the Z drive system 11 to move the sample table 1 up and down. A circuit, 12 is an XY drive system that moves the sample stage 1 in the XY directions in order to sequentially detect the unevenness of each point of the sample 2.

Next, the operation of the atomic force microscope apparatus constructed as described above will be described with reference to FIGS. 14 and 15. First, the laser light oscillated from the laser light oscillation source 7 and incident on the reflecting portion of the cantilever 3 through the optical system 6 comes into contact with the sample 2 fixed on the sample stage 1 via the atomic force 4. In the reflecting portion of the cantilever 3 having
Is reflected in the direction of. Therefore, if the surface of the sample 2 has irregularities, the atomic force acting between the sample 2 and the probe 4 changes according to the irregularities, and the cantilever 3 bends on the basis of the joint between the cantilever 3 and the support plate 5 as a fulcrum. For example, if there is a recess on the surface of the sample 2, the position shown by the solid line in FIG. 15 changes to the position shown by the dotted line. Then, the reflection position and the reflection angle of the laser light at the reflecting portion of the cantilever 3 change, so that the optical paths 16a to 16b of the laser light change.

The optical path of this laser light is changed by the reflecting mirror 9 and detected by the photosensor 8. In the photo sensor 8, as shown in FIG. 16, a change in the focal position of the laser light from a to a1 or from a to a2 is recognized.
The Z drive system 11 is actuated by the control circuit 10 which receives the focus movement amount signal from the photo sensor 8 to move the sample stage 1 up and down, and the focus position of the laser light on the photo sensor 8 is changed from a1 or a2 to a. Return. Then, the deflection of the cantilever 3 is restored, and the atomic force between the sample 2 and the probe 4 is kept constant. Therefore, if the sample 2 is horizontally moved by the XY drive system 12 with respect to the probe 4 by the raster scan method, the unevenness of a desired region of the sample can be enlarged and recognized by knowing the position coordinates of the sample table 1. You can

[0005]

Since the conventional atomic force microscope apparatus is constructed as described above, there is a problem that the detection sensitivity is low and the resolution is poor. The following are possible factors. As shown in FIG. 17, since the spot diameter of about 50 μm of the laser light incident on the reflecting portion of the cantilever 3 is larger than that on the reflecting portion provided at the tip of the cantilever 3, the laser light leaks onto the sample. The reflected light from is also input to the photo sensor 8 via the reflecting mirror 9. Since the lever action of the cantilever is insufficient, the amount of optical path deviation of the laser light corresponding to the unevenness of the sample 2 is insufficient. Since the optical system 6 cannot fully limit the luminous flux of the laser light, the luminous flux of the laser light spreads before reaching the photosensor.

The present invention has been made to solve the above problems, and an object thereof is to obtain an atomic force microscope apparatus having high detection sensitivity and good resolution.

[0007]

In the atomic force microscope apparatus according to the first aspect of the present invention, the cantilever is provided with a reflecting portion that is larger than the spot diameter of the laser beam incident on the cantilever.

In the atomic force microscope apparatus according to the second aspect of the present invention, the convex mirror for reflecting the laser beam incident on the cantilever is provided on the cantilever.

In the atomic force microscope apparatus according to the third aspect of the present invention, a convex mirror for changing the optical path of laser light is provided between the cantilever and the photosensor.

In the atomic force microscope apparatus according to the fourth aspect of the present invention, the cantilever is provided with a reflecting portion for receiving the laser beam outside the sample.

In the atomic force microscope apparatus according to the fifth aspect of the present invention, an optical system for converging laser light is provided between the cantilever and the photosensor.

[0012]

In the first aspect of the present invention, the reflecting portion provided on the cantilever prevents the laser beam from leaking onto the sample and reflects it on the sensor.

In the second aspect of the present invention, the convex mirror provided on the cantilever enlarges the optical path deviation amount of the laser light due to the unevenness of the sample and reflects it on the sensor.

In the third aspect of the present invention, the convex mirror provided between the cantilever and the sensor enlarges the optical path deviation amount of the laser beam due to the unevenness of the sample and makes it enter the sensor.

According to the fourth aspect of the present invention, the reflecting portion provided on the cantilever for reflecting the laser light outside the sample reflects the laser light reflected from the sample to the sensor.

In a fifth aspect of the present invention, an optical system provided between the cantilever and the sensor converges the light beam of the laser light reflected by the cantilever and reflects it on the sensor.

[0017]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to FIG. In FIG. 1, the same reference numerals as those in the conventional example shown in FIG. 14 indicate the same or corresponding portions, and 3a is a fulcrum at which both end portions fixed to the support plate 5 follow the vertical movement of the probe 4. The reflection of the laser beam incident on the main body of the V-shaped cantilever 3 whose tip moves up and down through the 3b optical system 6 and having a shape larger than the spot diameter of the laser beam at the tip of the cantilever 3 is reflected. Part, and is integrally provided at the tip portion of the main body 3b.
The probe 4 is provided on the lower surface of the reflecting portion 3b.

The operation of the atomic force microscope apparatus according to the first embodiment thus constructed will be described with reference to FIG. First, the laser light emitted from the laser light oscillation source 7 is reflected by the reflecting portion 3b provided at the tip of the cantilever 3 having the probe 4. Therefore, the cantilever 3 bends in accordance with the unevenness of the surface of the sample 2, and the reflection position and the reflection angle of the laser light on the reflecting portion 3b change, so that the optical path of the laser light changes.

The laser light reflected by the reflecting portion 3b is changed in its optical path by the reflecting mirror 9 and detected by the photosensor 8. However, as shown in FIG. 2, most of the laser light is reflected by the reflecting portion 3b. Therefore, the laser beam incident on the photosensor 8 has a small half-value width as shown by a solid line b1 in contrast to a laser beam having a conventional b-shaped light amount distribution shown by a dotted line as shown in FIG. The maximum strength increases as well. When the cantilever 3 bends, the focal point of the laser light moves to the position of b2, for example. In this way, the accuracy of the focus on the photosensor 8 and the accuracy of the movement amount of the focus are improved.
The Z drive system 11 is actuated by the control circuit 10 receiving the signal from the photo sensor 8 to move the sample table up and down, and the focus position of the laser light in the photo sensor 8 is returned from b2 to b1. If this is raster-scanned in the XY directions by the XY drive system 12, the unevenness of the desired region of the sample can be satisfactorily enlarged and recognized by knowing the position coordinates of the sample table 1.

Example 2. FIG. 4 shows a second embodiment of the present invention, in which the reflecting portion of the cantilever 3 in comparison with the first embodiment is a cylindrical surface which is convex toward the laser light incident through the optical system 6. The convex mirror 3c is made of In the atomic force microscope apparatus configured as described above, as shown in FIG. 5, the optical path of the laser beam corresponding to the unevenness of the sample 2 is indicated by a solid line 16a to, for example, a dotted line 16a.
Change to b. The laser light incident on the photo sensor 8 is
As shown in FIG. 6, the conventional optical path deviation amount is increased from c to c1 by the convex mirror 3c to be increased from c to c2, and the resolution is improved.

Example 3. FIG. 7 shows Embodiment 3 of the present invention, and the same reference numerals as those in the conventional example shown in FIG.
The same or corresponding parts are shown. In FIG. 7, 14
Is a convex mirror that is provided between the cantilever 3 and the photosensor 8 and changes the optical path of the laser light reflected from the reflecting portion at the tip of the cantilever 3 to the photosensor 8. FIG. 8 is an optical path diagram in the third embodiment,
In FIG. 8, when the cantilever is bent from 3 shown by the solid line to 13 shown by the dotted line, the optical path 16a is deviated to the optical path 16b shown by the dotted line when the conventional plane mirror 9 is used. If the convex mirror 14 in No. 3 is used, the optical path deviation amount is expanded to the optical path 16c, and the photosensor 8
Since it is incident on, the resolution is improved.

Example 4. 9 shows Embodiment 4 of the present invention, and the same reference numerals as those in the conventional example shown in FIG.
The same or corresponding parts are shown. 3b in FIG.
Is a reflection portion which is integrally formed by extending from the tip portion of the V-shaped main body 3a of the cantilever (3) and which receives and reflects the laser light from the laser light oscillation source 7 outside the vertical projection area of the sample 2. is there. FIG. 10 is an optical path explanatory diagram in the fourth embodiment, but in FIG. 10, when the cantilever bends from 3 shown by a solid line to 13 shown by a dotted line, an optical path 16a shown by a solid line goes to an optical path 16b shown by a dotted line. Be biased. The cantilever 3 according to the fourth embodiment expands the movement amount of the probe 4 according to the unevenness of the sample at the tip portion thereof, so that the optical path deviation amount of the laser light reflected by the reflecting portion 3b becomes smaller. , The resolution is improved because it is enlarged to that reflected at the position of the probe 4.

Example 5. FIG. 11 shows a fifth embodiment of the present invention, and the same reference numerals as those of the conventional example shown in FIG. 14 indicate the same or corresponding portions. In FIG. 11, reference numeral 15 denotes an optical system which is provided between the cantilever 3 and the photosensor 8 and which converges the light flux of the laser light which is reflected from the reflecting portion at the tip of the cantilever 3 and whose optical path is changed by the reflecting mirror 9. In the fifth embodiment, a convex lens is used. FIG. 12 shows how the light flux is narrowed in the fifth embodiment, but the optical system 15 has a conventional light quantity distribution on the photosensor 8 that does not use the optical system (shown by d in FIG. 13). On the other hand, the full width at half maximum becomes smaller and the maximum intensity becomes larger and becomes like dd, and the detection sensitivity is improved. The optical system 15 may be provided between the reflecting mirror 9 and the photosensor 8, between the cantilever 3 and the reflecting mirror 9, or both of them. Also, this optical system may be plural.

In the above-mentioned Examples 1 to 5, the probe 4 was projected from the lower surface of the cantilever 3, but any shape can be used as long as it makes contact with the sample via atomic force. good.

In the first to fifth embodiments, the laser beam is incident on the cantilever 3 in the direction of gravity. However, as long as the relative positional relationship of each constituent element is satisfied, It may be facing any direction.

In the first to fifth embodiments described above, the lever type is shown as the cantilever 3, but the cantilever 3 is not limited to this, and any type that can be displaced according to the unevenness of the sample may be used.

In the first to fifth embodiments, the mirror is shown as the reflecting mirror 9 for changing the path of the laser beam between the cantilever 3 and the photosensor 8, but any mirror can be used as long as it can change the optical path of the laser beam. , It may be a prism.

Although the probe 4 or the reflecting portion or the convex mirror is formed integrally with the cantilever 3 in the above-mentioned first to fifth embodiments, the probe 4 or the reflecting portion or the convex mirror can be detachably attached to the cantilever. It may be attached.

In the above embodiment, the cantilever is provided with a reflecting portion that is larger than the spot diameter of the laser beam incident on the cantilever at the tip of the cantilever. When a convex mirror that reflects the laser light incident on the cantilever is provided on the cantilever. When a convex mirror that changes the optical path of laser light is provided between the cantilever and the photo sensor. When using a cantilever that reflects laser light outside the sample. When an optical system for converging laser light is provided between the cantilever and the photo sensor. Although an example in which each of the cases has been individually implemented is shown, it goes without saying that the sensitivity and resolution can be further improved by combining a plurality of the respective examples.

[0030]

Since the present invention is configured as described above, it has the following effects.

In the atomic force microscope apparatus according to the first aspect of the present invention, since the cantilever is provided with the reflecting portion larger than the spot diameter of the incident laser beam, the noise reflected from the sample surface is reduced and the detection sensitivity is reduced. There is an effect that high quality can be obtained.

In the atomic force microscope apparatus according to the second aspect of the present invention, since the cantilever is provided with the convex mirror for reflecting the incident laser beam, the optical path deviation amount of the laser beam corresponding to the unevenness of the sample is enlarged. There is an effect that the resolution is improved.

In the atomic force microscope apparatus according to the third aspect of the present invention, since the convex mirror for changing the optical path of the laser light is provided between the cantilever and the photosensor, the optical path deviation of the laser light according to the unevenness of the sample is provided. This has the effect of increasing the amount and improving the resolution.

Since the atomic force microscope apparatus according to the fourth aspect of the present invention uses the cantilever that reflects the laser beam outside the sample region, noise reflected from the sample can be eliminated and detection sensitivity is improved. There is an effect of doing.

In the atomic force microscope apparatus according to the fifth aspect of the present invention, an optical system is provided between the cantilever and the photosensor to converge the light flux of the laser light, so that the detection sensitivity is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part showing a first embodiment of the present invention.

FIG. 2 is an enlarged view of a reflecting portion showing Embodiment 1 of the present invention.

FIG. 3 is a light amount distribution diagram on the photosensor showing the first embodiment of the present invention.

FIG. 4 is a main part configuration diagram showing a second embodiment of the present invention.

FIG. 5 is an optical path diagram showing a second embodiment of the present invention.

FIG. 6 is a light amount distribution diagram on a photosensor showing a second embodiment of the present invention.

FIG. 7 is a main part configuration diagram showing a third embodiment of the present invention.

FIG. 8 is an optical path explanatory diagram showing Embodiment 3 of the present invention.

FIG. 9 is a main part configuration diagram showing a fourth embodiment of the present invention.

FIG. 10 is an optical path explanatory diagram showing Embodiment 4 of the present invention.

FIG. 11 is a main part configuration diagram showing a fifth embodiment of the present invention.

FIG. 12 is a luminous flux explanatory diagram showing Embodiment 5 of the present invention.

FIG. 13 is a light amount distribution diagram on the photosensor showing the fifth embodiment of the present invention.

FIG. 14 is a main part configuration diagram showing a conventional atomic force microscope apparatus.

FIG. 15 is an optical path explanatory view showing a conventional atomic force microscope apparatus.

FIG. 16 is a light amount distribution diagram on a photosensor showing a conventional atomic force microscope apparatus.

FIG. 17 is an enlarged view of a reflection part showing a conventional atomic force microscope device.

[Explanation of symbols]

 3 Cantilever 3a Cantilever body 3b Reflecting part 3c Convex mirror 4 Probe 7 Laser light source 8 Photosensor 14 Convex mirror 15 Optical system

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Morita 4-1-1, Mizuhara, Itami City Mitsubishi Electric Corp. LSE Research Institute

Claims (5)

[Claims] 1. A laser beam oscillation source for irradiating a laser beam having a predetermined diameter, a probe that comes into contact with a sample through an atomic force, and a main body that follows the vertical movement of the probe. A cantilever provided in the main body, the cantilever having a reflection portion having a diameter larger than the diameter of the laser light reflected by receiving the laser light from the laser light oscillation source, and a sensor receiving the laser light reflected by the reflection portion of the cantilever. Atomic force microscope equipped. 2. A laser beam oscillation source for irradiating a laser beam having a predetermined diameter, a probe that comes into contact with a sample via an atomic force, and a main body that follows the vertical movement of the probe. Atomic force microscope apparatus provided with a cantilever having a convex mirror, which is provided in the main body and receives and reflects the laser light from the laser light oscillation source, and a sensor which receives the laser light reflected by the reflecting portion of the cantilever. . 3. A laser beam oscillation source that irradiates a laser beam having a predetermined diameter, a probe that comes into contact with a sample via an atomic force, and a main body that follows the vertical movement of the probe. A cantilever provided on the main body and having a reflecting portion for receiving and reflecting the laser light from the laser light oscillation source, a sensor for receiving the laser light reflected by the reflecting portion of the cantilever, and the cantilever and the sensor. An atomic force microscope apparatus provided with a convex mirror that is located in between and that changes the path of the laser light reflected by the reflecting portion of the cantilever toward the sensor. 4. A laser beam oscillation source for irradiating a laser beam having a predetermined diameter, a probe that comes into contact with a sample via an atomic force, and a main body that follows the vertical movement of the probe. , A cantilever provided on the main body and having a reflection portion for receiving and reflecting the laser light from the laser light oscillation source outside the vertical projection region of the sample, and the laser light reflected by the reflection portion of the cantilever. Atomic force microscope device equipped with a sensor to receive. 5. A laser beam oscillation source for irradiating a laser beam having a predetermined diameter, a probe that comes into contact with a sample through an atomic force, and a main body that follows the vertical movement of the probe. A cantilever provided on the main body and having a reflection portion for receiving and reflecting the laser light from the laser light oscillation source, a sensor for receiving the laser light reflected by the reflection portion of the cantilever, and a space between the cantilever and this sensor. An atomic force microscope apparatus provided with an optical system located at the position where the light flux of the laser light reflected by the reflecting portion of the cantilever is converged and made incident on the sensor.