JP3023686B2 - Tip microscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a technique in which a sharply pointed probe is brought close to a sample surface, such as a scanning tunneling microscope, an atomic force microscope, or an ion conductivity microscope. The present invention relates to a microscope for observing a fine structure of a sample surface (hereinafter referred to as a "probe microscope"), and more particularly to a probe microscope capable of observing a situation where a probe approaches a sample surface.

[Summary of the Invention] A probe microscope such as a scanning tunneling microscope, an atomic force microscope, or an ion conductivity microscope has a different observation principle, but a sharply pointed probe is brought close to the sample surface. Has a common point of observing the microstructure of the probe, and therefore has a structural common point for maintaining the relative positional relationship between the probe and the sample. The present invention provides a reflector near the probe in order to observe the situation in which the probe approaches the sample surface, and enables the elevation angle of the viewpoint to be as large as possible by viewing through the reflector. It is.

[Prior art] A probe that sharply sharpens the tip, such as a scanning tunneling microscope, an atomic force microscope, or an ion conductivity microscope, and approaches the sample surface to observe the microstructure of the sample surface on a micron to atomic scale. Microscope technology has made great progress in recent years and has achieved results in a wide range of fields.

A common technique is to observe the fine structure of the sample surface by moving a sharply pointed probe close to the sample surface and tracing the probe tip at a small distance to the sample surface. It is.

For example, in the case of a scanning tunneling microscope, the following description will be given based on FIG. When the metal probe 1 is brought close to the surface of the conductive sample 2 to about 1 nm and then a minute voltage is applied between the two, a current flows due to a tunnel effect.
This current is called a tunnel current and is very sensitive to the distance between the two, and changes by almost one digit for a distance change of 0.1 nm.
Therefore, if the tip is driven and controlled to keep the tunnel current constant, the distance between the two can be kept constant with high accuracy. In this state, if the tip is scanned over the sample surface, the tip will be driven The driving distance of the probe in the direction perpendicular to the sample surface can be determined from the control signal, and therefore, the shape of the sample surface can be measured on the atomic scale. The voltage applied between the probe and the sample is generated by a bias voltage generator 14, and the tunnel current is
The probe is driven and controlled by the fine movement actuator 17 through the feedback circuit 16 so as to keep the tunnel current constant. The scanning of the probe on the sample surface is performed by scanning the scanning signal from the scanning signal generator 18 with the fine movement actuator 19,
Apply to 20. The fine movement actuators 17, 19, 20 use, for example, piezoelectric elements. If the drive control signal 21 corresponding to the driving distance of the probe is imaged by the data processing device 23 together with the scanning signal 22 of the probe surface of the sample, the shape of the sample surface can be observed as a visible image.

In the case of the atomic force microscope, the force (atomic force) acting between the probe 1 and the surface of the sample 2 is detected by a very sensitive spring 24 and a spring deflection sensor 25 as shown in FIG. To keep the distance between them. That is, the tunnel current in the scanning tunneling microscope is an atomic force. The spring deflection sensor 25 includes, for example, a laser diode 26, photodetectors 27 and 28, and a differential amplifier 29. The light 30 emitted from the laser diode 26 is reflected by a spring and received by two photodetectors 27 and 28.
Photodetector by changing the optical path due to spring deflection
The amount of light incident on the photodetector 27 increases (decreases), and the amount of light incident on the photodetector 28 decreases (increases). If the outputs of the photodetectors 27 and 28 are input to the operation amplifier 29, the output of the operation amplifier 29 is different, that is, a signal corresponding to the atomic force acting between the probe and the sample surface is obtained. Thus, the tunnel current in the scanning tunneling microscope is an atomic force, and the accompanying control circuit and data processing circuit are the same as in FIG. 6, and in FIG. Omitted.

In the case of the ion conductivity microscope, as shown in FIG. 8, the ion current flowing between the surface of the sample 2 in the electrolytic solution E and the probe 1a of the capillary made of an insulator such as glass is detected. And keep the distance between them. That is, the tunnel current in the scanning tunneling microscope is an ion current. There is an electrode 32 in the electrolytic solution E in which the sample is immersed, and an electrode 31 in the probe of the capillary in which the same electrolytic solution E as the above electrolytic solution is viewed. When a voltage is applied between the electrodes 31 and 32 by the bias voltage generator 14, the electrolyte E
The ion current flows through. This ion current changes depending on the distance between the probe and the sample. For example, when the distance between the two is zero, the tip of the capillary and the sample are in close contact, the electrolytic solution E in which the two electrodes 31 and 32 are immersed is cut off, and the ionic current is zero, but the distance between the two is small. Opening it little by little increases the ion current accordingly. As described above, the tunnel current in the scanning tunneling microscope is an ion current, and the accompanying control circuit and data processing circuit are the same as in FIG. 6 and are omitted in FIG. I have.

Details regarding these are provided in the following documents, for example.

G. Binnig, H. Rohrer et al .: Surface Studies by Scan
ning Tunneling Microscopy, Appl.Phys.Lett.Vol.49, N
o.1, pp.178-180 (1982) or Koji Kajimura, Masatoshi Ono, et al .: Scanning Tunneling Microscope, Solid State Physics, Vol.22, No.3, pp.32-47 (1987) .120-123 (19
83). For details of the atomic force microscope, see PKHansma, et al .: An Atomic-resolution atomic-
force microscope implemented using an optical leve
r, J. Appl. Phys. Vol 65, No. 1, pp. 164-167 (1988) For details of the ion conductivity microscope, see PK Hansma, et al .: Scanning Ion-Conductance Micr.
Scope, Science, Vol. 243, pp. 641-643 (1989).

When observing the sample surface with the above-described probe microscope, it is important to know where the probe is facing the sample surface to observe the sample. Conventionally, as a means for this purpose, the condition of the sample surface and the opposing probe is visually observed from the observation window 10a of the housing 10 as shown in FIG. 9, or an optical microscope such as a stereo microscope as shown in FIG. 33 was used.

[Problems to be Solved by the Invention] As described above, in a scanning tunneling microscope, an atomic force microscope, or an ion conductivity microscope, those that are detected as an interaction between a probe and a sample are a tunnel current and an atomic force, respectively. Although it is different from the ion current, it is the same in that the probe having a sharply pointed tip is brought close to the sample surface to observe the fine structure of the sample surface. The gist of the present invention relates to a means for observing a situation in which the probe is approaching the surface of the sample in opposition to the probe. What is detected as an interaction between the two is a tunnel current, an atomic force, or an ionic current. It is completely unaffected by being. Therefore, hereinafter, it will be described simply by using a probe microscope.

In a probe microscope, the probe and the sample are generally arranged as shown in FIG. That is, the sample 2 is fixed to the sample holder 5 by the clamper 6, and the sample holder 5 is attached to the sample stage 9 for moving the sample in the in-plane direction of the sample surface. The probe 1 is attached to a fine movement scanner 7 so as to scan on the surface of the sample 2. This fine movement scanner is realized by, for example, a piezoelectric element of PZT (lead zirconate titanate). Further, the fine movement scanner 7 has a coarse movement mechanism 8.
Attached to. The coarse movement mechanism 8 includes a probe 1 immediately after the sample 2 is mounted on the sample stage 9 via the sample holder 5.
This is a mechanism for preliminarily bringing the distance between the sample and the sample 2 from a distance of about several millimeters to a distance of 1 micron or less, which is a distance that can be controlled by the fine movement scanner, and is a very important mechanism in practical use. The coarse movement mechanism 8 may be provided on the sample side. The coarse movement mechanism 8 and the sample stage 9 are connected via a housing (or frame) 10. The housing 10 is installed via the vibration isolation mechanism 11 so as to be insulated from external vibration.

In order to put such a probe microscope into practical use, it is necessary to stably observe it. That is, the influence should be negligible with respect to a slight vibration passing through the vibration isolation mechanism 9 or a change in the temperature of the room where the device is installed. For that purpose, it is important to increase the rigidity of the structure to which the probe 1 and the sample 2 are attached, and thus the shape must be reduced in size.

As a result, when trying to view the surface of the sample 2 facing the probe 1, the elevation angle of the line of sight had to be very small as shown in FIG. When using a piezoelectric element driven by high voltage as a fine movement scanner,
In some cases, the cover 12 is attached to prevent electric shock and protect the fine movement scanner. In such a case, the elevation angle of the line of sight becomes even smaller.

As described above, the probe microscope is a means for observing the surface of a sample on a micron to atomic scale, and the surface of the sample to be observed is visible and optically flat. Therefore, if the elevation angle of the line of sight is large, the observation part of the sample surface which the probe opposes can be seen. However, since the elevation angle of the line of sight is small, the surface of the sample 2 acts like a mirror, and the probe 1 is opposed. However, there is a problem that it is very difficult to see the situation of the sample surface itself in the place where it is performed.

[Means and Actions for Solving the Problems] The present invention provides a reflector near the probe, and observes the reflection image of the surface of the sample facing the probe by observing the reflection image of the reflector.
The elevation angle of the line of sight can be substantially increased, and the situation of the sample surface itself where the probe is opposed can be clearly seen without the surface of the sample acting like a mirror.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1A is a diagram of an embodiment in which a reflecting mirror is installed in a scanning tunnel microscope.

The probe 1 is attached to one end of a fine movement scanner 7,
The other end of the fine movement scanner 7 is attached to a moving table 8a that is moved by the coarse movement mechanism 8.

The coarse movement mechanism 8 has a built-in movement mechanism in the x, y, and z directions,
The moving table 8a is capable of coarse movement in the x, y, and z directions.

An arm 3a for attaching a reflecting mirror is attached to the movable table 8a, and the reflecting mirror 3 is provided at the tip of the arm 3a near the tip of the probe 1 with a variable tilt angle.

Therefore, the vicinity of the tip of the probe 1 and the sample surface facing the probe 1 can be observed via the reflecting mirror 3 with the elevation angle larger than the observation window 10a of the housing 10.

FIG. 1B is an enlarged view of the probe 1, the sample 2, and the reflecting mirror 3. As is apparent from FIG. 1, the effective elevation angle A of the line of sight 4 by the reflecting mirror 3 is large. Become.

FIG. 2 shows an example in which the reflection image of the reflecting mirror 3 is observed not by visual observation but by the optical microscope 33, in which the optical microscope 33 is installed in the housing 10. The optical microscope used here preferably has a long working distance (distance between the objective lens and the sample). In this example,
The reflecting mirror 3 is provided at the tip of the arm 3a attached to the protective cover 12 of the fine movement scanner 7 at an angle.

As a means for observing the reflected image, an optical observation means such as a magnifying lens and a TV camera can be used in addition to the optical microscope.

FIG. 3 is a view showing another embodiment of attachment of the reflecting mirror 3. In this example, a hole 13 through which the probe 1 passes is formed in the reflector 3 as shown in FIG. It is installed at the tip of the mounting arm 3a. The reflector mounting arm 3a is mounted on the movable base 8a, the protective cover 12, and the like, as in the previous embodiment. The reflected image from the reflecting mirror 3 is observed visually or by an optical microscope as shown in FIGS.

In the case of this example, the elevation angle of the line of sight 4 can be further increased.

Next, an example in which a reflecting mirror is installed in an atomic force microscope will be described with reference to FIG.

A very sensitive leaf spring 24 that detects atomic force is a support 24a
The probe 1 is fixed to the other end. As described above with reference to FIG. 7, the measurement principle is as follows: the displacement of the leaf spring 24 due to the atomic force is expressed by the laser diode 26, the photo detector 27,
The fine structure of the sample 2 is detected by the detection by the sensor unit 25 including 28 and the like.

The sample 2 is placed on a sample holder 5, and the sample holder 5 is mounted on a fine movement scanner 7. Fine movement scanner 7 on which fine movement actuators 17, 19 and 20 are formed
Is mounted on the moving table 8a of the coarse movement mechanism 8.

Also in this example, the reflecting mirror 3 is provided at the tip of the arm 3a attached to the housing 10 so as to be inclined, and is installed near the tip of the probe 1 or in the hole of the reflecting mirror shown in FIG. You.

The reflected image from the reflecting mirror 3 is shown in FIG.
It is observed visually or by an optical microscope as shown in the figure.

FIG. 5 (b) is a diagram showing an example in which the reflecting mirror 3 is installed in the ion conductivity microscope. A reflecting mirror 3 is set near or through a probe 1a of a capillary made of an insulating material such as glass in which an electrolyte E is viewed, and the reflection image is observed visually or by an optical microscope. The observation principle of the ion conductivity microscope is as described above with reference to FIG.

By installing the reflecting mirror in various probe microscopes in this way, the effective elevation angle can be increased, and the situation in which the probe and the sample approach each other can be easily and reliably observed.

[Effect of the Invention] The situation where the probe is facing the sample surface to be finely observed with the probe microscope, in other words, the condition of the sample surface which is to be observed with the probe microscope Can be easily confirmed, and unnecessary observation due to misperception can be avoided.

[Brief description of the drawings]

FIG. 1 (a) is a diagram of a scanning tunnel microscope according to an embodiment of the present invention in which a reflecting mirror is installed, FIG. 1 (b) is a partially enlarged view of FIG. 1 (a), and FIG. FIG. 3 is a view showing an example in which an optical microscope for observing a reflected image is installed, FIG. 3 is a view showing an example in which a reflecting mirror is installed through a probe, FIG. 4 is an embodiment of the reflecting mirror in FIG. 3, FIG. FIG. 5A is a diagram in which a reflection is installed in an atomic force microscope, FIG. 5B is a diagram in which a reflection mirror is installed in an ion conductivity microscope, FIG. 6 is a conceptual diagram of a scanning tunneling microscope, and FIG.
FIG. 8 is a conceptual diagram of an atomic force microscope, FIG. 8 is a conceptual diagram of an ion conductivity microscope, FIG. 9 is a structural diagram of a conventional probe microscope, and FIG.
FIG. 11 is a structural diagram of a conventional probe microscope with an optical microscope, and FIG. 11 is a diagram showing an elevation angle of a conventional line of sight. DESCRIPTION OF SYMBOLS 1 ... Probe 1a ... Capillary probe 2 ... Sample 3 ... Mirror 3a ... Arm 4 ... Line of sight 5 ... Sample holder 6 ... Clamper 7 ... Fine scanner 8 ... Coarse movement mechanism 8a ...... Moving stage 9 ... Sample stage 10 ... Housing 10a ... Observation window 11 ... Vibration isolation mechanism 12 ... Cover 13 ... Hole 14 ... Bias voltage generator 15 ... Amplifier 16 ... Feedback circuit 17 … Fine actuator 18… Scanning signal generator 19… Fine actuator 20… Fine actuator 21… Drive control signal 22… Scan signal 23… Data processing unit 24… Spring 24a… Support 25… Sensor 26 Laser diode 27 Photo detector 28 Photo detector 29 Differential amplifier 30 Light 31 Electrode 32 Electrode 33 Optical microscope (optical observation means) E Electrolyte

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B 21/30 H01J 37/28 G01B 7/34

Claims (5)

(57) [Claims] 1. A probe provided to face a sample surface, a mechanism for controlling a relative position between the tip of the probe and the sample surface, a housing for accommodating the probe, the sample, and the mechanism, and the housing A probe window for observing the fine structure of the sample surface by scanning the tip of the probe at a small distance from the surface of the sample. A reflecting mirror disposed in the vicinity of the probe so that a situation in which the probe faces the sample can be observed, and a reflected image of the reflected image can be obtained by a sample window of the housing or an optical observation unit attached to the housing. A probe microscope characterized in that the elevation angle of the viewpoint is substantially increased by observing the image. 2. A control mechanism including a probe provided opposite to a sample surface and attached to one end of a fine-movement scanner, and the fine-movement scanner controlling a relative position between the tip of the probe and the sample surface. A housing for accommodating the components, and a sample window of the housing or optical observation means attached to the housing, and the tip of the probe is scanned at a small distance from the surface of the sample to scan the surface of the sample. In the probe microscope for observing the fine structure of the above, a reflecting mirror is arranged below the end of the fine motion scanner and near the opposing portion of the probe and the sample, and is provided by a sample window of the housing or optical observation means attached to the housing. A probe microscope characterized by substantially increasing the elevation angle of the viewpoint by observing the reflected image. 3. A probe provided to face a sample surface, the probe support, a mechanism for controlling a relative position between the tip of the probe and the sample surface, and a housing for accommodating each of the constituent elements. And a sample window provided in the housing or optical observation means attached to the housing, and scanning the tip of the probe at a small distance from the surface of the sample to form a fine structure on the surface of the sample. In the probe microscope to be observed, near the probe, a reflecting mirror held at the end of the arm held by the support portion so that the situation where the probe faces the sample is provided, A probe microscope wherein the elevation angle of the viewpoint is substantially increased by observing the reflected image by a sample window of the housing or an optical observation means attached to the housing. 4. The probe microscope according to claim 3, wherein the reflecting mirror is attached to the arm so as to be variable in inclination angle. 5. The reflector according to claim 1, wherein a hole through which the probe is formed is formed in the reflector, and the reflector is inclined with the probe being passed through the hole. The probe microscope according to any one of claims 1 to 4.