JPH03257310A - Probe microscope - Google Patents

Abstract

PURPOSE:To prevent that the surface of a sample works as a mirror face thereby to hinder observation, and to clearly confirm the surface of the sample in a position confronting a probe by providing a reflecting mirror in the vicinity of the probe and enlarging an elevation of the line of vision observing the surface of the sample. CONSTITUTION:In a scanning tunnel microscope, a probe 1 is provided at one end of a microscanner 7. The other end of the scanner 7 is fixed to a moving stage 8a moved by a mechanism 8 for rough adjustment. The moving stage 8a is provided with a reflecting mirror 3 an inclining angle of which is variable via a mounting arm 3a. The vicinity of an end of the probe 1 and the sample face confronting the probe 1 are observed from an observation window 10a of a housing 10 via the reflecting mirror 3. In this manner, an effective elevation A of the line of vision 4 by the reflecting mirror 3 is enlarged, and the state where the probe 1 is close to the sample can be easily and positively observed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a scanning tunneling microscope, an atomic force microscope, an ion conductivity microscope, etc., in which a probe with a sharp tip is brought close to a sample surface. The present invention relates to a microscope (hereinafter referred to as a "probe microscope") for observing the fine structure of the surface of a sample using a probe, and particularly to a probe microscope that allows observation of the state in which a probe approaches the sample surface.

[Summary of the Invention] Probe microscopes such as scanning tunneling microscopes, atomic force microscopes, and ion conductivity microscopes use different principles for observation, but they involve moving a probe with a sharp tip close to the sample surface. They have a common feature of observing the fine structure of
Therefore, there is a common feature in structure for maintaining the relative positional relationship between the probe and the sample. In the present invention, a reflecting mirror is provided near the probe in order to observe the situation in which the probe approaches the sample surface.
This is so that the angle of elevation of the viewpoint can be made as large as possible by viewing through the reflecting mirror.

[Prior technology] Scanning tunneling microscopes, interatomic square-head mirrors, ion conductivity microscopes, and other devices bring a probe with a sharp tip close to the sample surface to examine the fine structure of the sample surface from microns to atomic scales. The technology of the 11-scope microscope used for observation has made great progress in recent years, and has produced results in a wide range of fields.

The common technique for these is to bring a probe with a sharp tip close to the sample surface and trace the tip of the probe over the sample surface at a short distance to observe the fine structure of the sample surface. It is.

For example, in the case of a scanning tunneling microscope, the explanation will be as follows based on FIG. When the metal probe 1 is brought close to the surface of the conductive sample 2 to about 1 nm and a minute voltage is applied between the two, a current flows due to the tunnel effect.

This current is called a tunnel current, and is very sensitive to the distance between the two, and changes by approximately one order of magnitude for a change in distance of 0.1 nm. Therefore, by controlling the drive of the probe so as to keep the channel current constant, the distance between the two can be kept constant with high precision, and if the probe is scanned over the sample surface in this state, the tip The driving distance of the probe in the direction perpendicular to the sample surface can be determined from the drive control signal, and therefore the shape of the sample surface can be measured on an atomic scale. The voltage applied between the probe and the sample is generated by a bias voltage generator 14, the tunnel current is amplified by an amplifier 15, and the probe is driven and controlled by a fine movement actuator 17 through a feed hack circuit 16 to keep the tunnel current constant. do. Scanning of the probe over the sample surface is performed by applying a scanning signal from a scanning signal generator 18 to a fine movement actuator 19,20.

The fine movement actuators 17, 19, 20 use, for example, piezoelectric elements. Drive control signal 21 corresponding to the driving distance of the probe
If this is converted into an image by the data processing device 23 together with the scanning signal 22 of the sample surface of the probe, the shape of the sample surface can be observed as a visible image.

In the case of an atomic force microscope, as shown in Figure 7, the force (atomic force) acting between the probe 1 and the surface of the sample 2 is detected by a very sensitive blade 24 and a blade deflection sensor 25. to maintain distance between the two. In other words, in a scanning tunneling microscope &
This means that the tunnel current becomes an atomic force.

The deflection sensor '25 includes, for example, a laser diode 26, a photodetector 27, 28, and a differential amplifier 29.
Consisted of. The light 30 generated from the laser diode 26 is reflected by the blade and then sent to two fumetodetectors 2.
The light was received at 7.28. Due to the change in the optical path due to the deflection of the wing, the amount of light that enters the photodetector 27 increases (decreases), and conversely, the amount of light that enters the photodetector 28 decreases (increases). If the outputs of the fumeto detectors 27 and 28 are input to the operational amplifier 29, the output of the operational amplifier 29 will be different, that is, a signal corresponding to the atomic force acting between the probe and the sample surface will be obtained. In this way, the tunneling current in a scanning tunneling microscope becomes an atomic force, and the accompanying control circuit, data processing circuit, etc. are the same as in Figure 6, and in Figure 7. It is omitted.

In addition, in the case of an ion conductivity microscope, as shown in Figure 8, the ionic current flowing between the surface of the sample 2 in the electrolytic solution E and the capillary probe 1a made of an insulating material such as glass is detected. and maintain distance between them. In other words, the tunneling current in a 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 a capillary whose inside is filled with an electrolytic solution E similar to the electrolytic solution. When a voltage is applied between the electrodes 31, 32 by the bias voltage generator 14, an ionic current flows through the electrolyte E.

This ion current changes depending on the distance between the probe and the sample.

For example, when the distance between them is zero, the tip of the capillary and the sample are in close contact, the electrolyte E in which the two electrodes 31 and 32 are immersed is cut off, and the ionic current is zero, but the distance between them is If you open it little by little, the ionic current will increase accordingly. In this way, the tunneling current in a scanning tunneling microscope is an ion current, and the accompanying control circuits, data processing circuits, etc. are the same as shown in Figure 6, and are omitted in Figure 8. It is.

Details regarding these can be found, for example, in the documents below.

For scanning tunneling microscopy, G. B1nn1g, H. Rohrer et al.:
5urface 5tudiasby Scannin
g Tunneling Microscopy, Ap
pl, Phys.

Lett, Vol. 49. No, 1. I) p, 178
-180 (19B2) or Koji Kajimura, Masatoshi Ono et al.: Scanning tunneling microscope, Solid State Physics, Vol. 22. No, 3. pp, 32-47 (
1987).

120-123 (1983).

For details on atomic force microscopy, see Hansma et al.: An Atom.
ic-resolution atomic-force
m1croscope implemented u
singan optical 1ever, J, Ap
pl, Phys, Vo165+No, 1pp, 164
-167 (198B) For details on ion conductivity microscopy, see I'.
llansma, et al.: Scanning I
on-Conductance Microscope,
5science, Vo 1.243. pp, 64
1-643 (1989).

When observing the sample surface using a probe microscope as described above,
It is important to know where on the sample surface the probe is facing when observing the sample. Conventionally, as a means for this purpose, the situation of the sample surface and the gradual opening that opposes it can be visually observed through the observation window 10a of the housing IO as shown in FIG. 9, or with an optical microscope such as a stereomicroscope as shown in FIG. 33 was used.

[Problem to be solved by the invention 1] As mentioned above, scanning tunneling microscopes, atomic force microscopes, and ion conductivity microscopes detect tunneling current and atomic force as interactions between the probe and the sample, respectively. Although it is different from ion current, it is similar in that a probe with a sharp 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 the situation in which the probe approaches the sample surface, and what is detected as the interaction between the two is tunnel current, atomic force, or ionic current. It is completely unaffected by the fact that it exists. Therefore, from now on, we will explain the car as 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 in the sample holder 5.
The sample holder 5 is attached to a sample stage 9 for moving the sample in the in-plane direction of the sample surface. The probe l is attached to a fine movement scanner 7 so that it can scan the surface of the sample 2. This fine movement scanner is realized, for example, by a piezoelectric element made of PZT (lead zirconate titanate). Furthermore, the fine movement scanner 7 is the coarse movement scanner N4.
It can be attached to B. This coarse movement mechanism 8 moves from a state in which the distance between the probe 1 and the sample 2 immediately after attaching the sample 2 to the sample stage 9 via the sample holder 5 to a distance of several millimeters that can be controlled by a fine movement scanner. is 1,,
This is a mechanism that allows you to approach the target to a distance less than that of a chronograph, and is an extremely important mechanism in practical terms. The coarse movement mechanism 8 may be provided on the trial set 1 side. The coarse movement mechanism 8 and the sample stage 9 are connected via a housing (or frame) 10. Further, the housing 10 is installed via a vibration isolating mechanism 11 so as to be insulated from external vibrations.

In order to put such a probe microscope into practical use, it is necessary to be able to perform observations stably. That is, the influence of slight vibrations passing through the vibration isolation mechanism 9 and changes in the temperature of the room in which the device is installed must be negligible. To this end, it is important to increase the rigidity of the structure to which the probe 1 and sample 2 are attached, and therefore the shape must be made smaller.

As a result, when trying to view the surface of the sample 20 facing the probe 1, the elevation angle of the line of sight has to be a very small angle as shown in FIG. When using a high voltage driven piezoelectric element as a fine movement scanner,
In some cases, a cover 12 is attached to prevent electric shock and to protect the fine movement scanner, and in such a case, the elevation angle of the line of sight becomes even smaller.

As mentioned above, the probe microscope is a means for observing the surface of a sample from a micron to an atomic scale, and the surface of the sample to be observed is flat in terms of visible optics. Therefore, if the elevation angle of the line of sight is large, the observation part on the sample surface that the probe is facing can be seen, but since the elevation angle of the line of sight is small, the sample 2
There is a problem in that the surface acts like a mirror and it is very difficult to see the condition of the sample surface mill 1 where the probe 1 is facing.

[Means and effects for solving the problems] The present invention includes a reflecting mirror near the probe tip, and the line of sight of the surface of the sample facing the probe 11 is observed by observing the reflected image of the reflecting mirror. The angle of elevation can be substantially increased, and the state of the sample surface itself where the probe is facing can be clearly seen without the sample surface acting like a mirror.

[Example] Hereinafter, an example of the present invention will be described based on FIGS. 1 to 5.

FIG. 1(B) is a diagram of an embodiment in which a reflecting mirror is installed in a scanning tunneling microscope.

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

The coarse movement mechanism 8 has a built-in movement mechanism in the x, y, and z directions, and 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 so as to be inclined at a variable inclination angle.

Therefore, the vicinity of the tip of the probe 1 and the sample surface facing the probe 1 are viewed through the reflecting mirror 3 through the observation window 10a of the housing 10.
It can be observed at a larger angle of elevation.

FIG. 1(b) is an enlarged view of the probe 1, sample 2, and reflector 3. As is clear from this figure, the effective elevation angle A of the line of sight 4 due to the reflector 3 can be increased. Become.

FIG. 2 shows an example in which the reflected image of the reflecting mirror 3 is observed using an optical microscope 33 instead of visually, and the optical microscope 33 is installed in the housing 10. The optical microscope used here should preferably have a long working distance (distance # between the objective lens and the sample).

In this example, the reflecting mirror 3 is provided in an inclined manner at the tip of an arm 3a attached to the protective cover 12 of the fine movement scanner 7.

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

FIG. 3 is a diagram showing another example of how the reflecting mirror 3 is attached. In this example, the probe 1 is attached to the reflector 3 as shown in FIG.
A hole 13 is formed through which the probe 1 passes, and when the probe 1 is passed through the hole 13, the reflector 3 is tilted and attached to the reflector mounting arm 3a.
It is installed at the tip of the The reflector mounting arm 3a is attached to the moving table 8a, the protective cover 12, etc., as in the previous embodiment. The reflected image from the reflecting mirror 3 is the first
As shown in Fig. 2, it is observed visually or with an optical microscope.

In this example, the elevation angle of the line of sight 4 can be made even larger.

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

A very sensitive leaf spring 24 that detects atomic forces is attached to the strut 24.
a, and a probe 1 is fixed to the other end. As described above with reference to FIG. 7, the measurement principle is to detect the displacement of the leaf spring 24 due to atomic force using the sensor section 25, which includes the laser diode 26, photodetectors 27, 28, etc., and observe the fine structure of the sample 2.

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

In this example as well, the reflector 3 is installed obliquely at the tip of the arm 3a attached to the housing 10, and is installed near the tip of the probe 1 or through the probe l through the hole in the reflector shown in FIG. Ru.

The reflected image from this reflecting mirror 3 is shown in FIG.

As shown in FIG. 2, it is observed visually or with an optical microscope.

FIG. 5(b) is a diagram showing an example in which a reflecting mirror 3 is installed in an ion conductivity microscope. A reflecting mirror 3 is installed near or through the probe 1a of a capillary made of an insulating material such as glass and filled with an electrolytic solution E, and its reflected image is observed visually or with an optical 8Jii mirror. The observation principle of the ion conductivity microscope is as described above with reference to FIG.

By installing a reflecting mirror in various probe microscopes in this manner, the effective angle of elevation can be increased, and the state in which the probe and the sample are close can be observed easily and reliably.

[Effects of the invention] The situation where the probe faces the sample surface where the probe is facing the sample to be minutely observed with the probe microscope, in other words, the situation of the sample surface where the probe is to be observed with the probe microscope. This makes it easier to confirm and avoid unnecessary observations due to misidentification.

[Brief explanation of drawings]

FIG. 1(a) is a diagram of a reflecting mirror installed in a scanning tunneling microscope according to an embodiment of the present invention, FIG. 1(b) is a partially enlarged view of FIG. 1(a), and FIG. 2 is a diagram of a reflecting mirror installed in a scanning tunneling microscope. Figure 3 is a diagram of an example in which an optical microscope is installed to observe reflected images, Figure 3 is a diagram of an example in which a reflector is installed through a probe, Figure 4 is an example of the reflector in Figure 3, and Figure 5 ( a) is a diagram with a reflective mirror installed on an atomic force DI mirror, Figure 5 (b) is a diagram with a reflective mirror installed on an ion conductivity microscope, Figure 6 is a conceptual diagram of a scanning tunneling microscope, and Figure 7: Atomic Figure 8 is a conceptual diagram of a force microscope, Figure 8 is a conceptual diagram of an ion conductivity microscope, Figure 9 is a structural diagram of a conventional probe microscope, Figure 1
Diagram O is a structural diagram of a conventional probe microscope with an optical microscope.
FIG. 1 is a diagram showing the elevation angle of the conventional line of sight. 1... Probe 1a... Capillary probe 5 6 2... Sample 3... Reflector 3a... Arm 4... Line of sight 5... Sample holder 6... Clamper 7...・Fine movement scanner 8...Coarse movement mechanism 8a...Moving table 9...Sample stage lO...Housing 10a...Observation window 11...Vibration isolation mechanism 12...Cover 13...Hole 14 ...Bias voltage generator 15...Amplifier 16...Feed bank circuit 17...Fine movement actuator 18...Scanning signal generator 19 ・ ・ 20 ・ ・ 21 ・ ・ 22 ・ ・ 23 ・ ・ 24 ・・ 24a ・ 25 ・ ・ 26 ・ ・ 27 ・ ・ 28 ・ ・ 29 ・ ・ 30 ・ ・ 31 ・ ・ 32 ・ ・ 33 ・ ・ E ・ ・ ・ ・ Fine movement actuator, fine movement actuator, drive control signal, scanning signal, data processing Equipment, spring, support, sensor, laser diode, photodetector, photodetector, differential amplifier, light, electrode, electrode, optical microscope (optical observation means), electrolyte and above

Claims (5)

[Claims] (1) Consisting of a sample, a probe provided opposite to the sample surface, and a mechanism for controlling the relative position of the tip of the probe and the sample surface, the tip of the probe is slightly attached to the sample surface. In a probe microscope that observes the fine structure of a sample surface by scanning at a distance, the probe microscope is characterized in that a reflecting mirror is provided so that the situation in which the probe faces the sample can be observed. probe microscope. (2) The probe microscope according to claim 1, further comprising optical observation means as an observation means for viewing the reflected image of the reflecting mirror. (3) The probe microscope according to claim 1 or 2, wherein the probe microscope is a scanning tunneling microscope. (4) The probe microscope according to claim 1 or 2, wherein the probe microscope is an atomic force microscope. (5) Claim 1 wherein the probe microscope is an ion conductivity microscope.
Or the probe microscope described in 2.