JPH08161778A - Information processor - Google Patents

Abstract

PURPOSE: To obtain an information processor in which the resolution of a probe is enhanced by a method wherein a frictional force generated at a time when the probe is scanned in a state that a probe tip has been brought close to, or brought into contact with, a medium is reduced by applying a voltage across the probe and the medium. CONSTITUTION: A reverse-potential signal from a reverse-potential-signal application means 108 is applied across a probe 101 and a medium 104 so as to offset a potential-difference signal generated across the probe 101 and the medium 104. When a potential difference generated in the generation process of dynamic friction is reduced in this manner, a frictional force which is generated across a probe tip 103 and a recording face or a sample face 105 can be reduced. As a result, the resolution of the probe and the reliability of a recording and reproducing operation can be enhanced, and the power consumption of an information processor can be reduced sharply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to information processing such as an information recording / reproducing apparatus for writing / reading information by a physical interaction between a probe and a medium (recording medium or sample) or a scanning probe microscope for observing the surface. It relates to the device.

[0002]

2. Description of the Related Art In recent years, a scanning tunneling microscope (hereinafter abbreviated as STM) capable of observing the surface of a conductive material with a resolution of nanometer or less as described in US Pat. No. 4,434,993 has been developed. The atomic arrangement on the semiconductor surface and the orientation of organic molecules have been observed on an atomic / molecular scale. Further, by developing STM technology, an atomic force microscope (hereinafter abbreviated as AFM) capable of observing the surface of an insulating material or the like with the same resolution as STM was also developed (US Pat. No. 4,724,318). The scanning probe microscope is a general term for a technique of measuring the surface state of a sample by scanning the sample surface with the probe while detecting various interactions depending on the distance between the samples. Among them, the AFM uses the atomic force acting between the probe and the sample surface, so that the observation sample can observe not only the conductive substance such as a metal but also the surface of an insulating substance including an organic substance. There are advantages.

The basic configuration of a general AFM device will be described below. The probe has a sharply pointed tip and is formed near the free end of the cantilever. An actuator such as a piezoelectric element is attached to the cantilever or the sample support so that it can be displaced in three dimensions, and the probe and the sample support are configured to be capable of relative three-dimensional operation. There is. When the probe is brought closer than a few angstroms to the sample surface, an atomic force acts on the probe-sample surface. The cantilever bends in conjunction with the action of the probe displaced according to the interatomic force. That is, the cantilever bends according to the atomic force between the probe and the recording medium. In order to keep this atomic force constant, that is, to keep the amount of bending of the cantilever constant, the probe is scanned over the sample while adjusting the height from the sample support, and the amount of change in the height of the probe is measured. It is possible to obtain the unevenness information of the sample surface from. On the other hand, when the probe is scanned on the sample surface while keeping the height from the sample support base constant with the probe close to the sample surface at a distance where the atomic force acts between the probe tip and the sample surface, the probe is Since it is displaced according to the unevenness of the sample, it is possible to obtain the unevenness information of the sample surface from the amount of bending of the cantilever. As a method of detecting the curvature of the cantilever, an optical lever method using laser light or a laser interference method is often used. In these methods, the cantilever curvature is detected by irradiating the tip of the cantilever and detecting the laser light reflected on the back surface of the cantilever with a 2- or 4-division optical sensor.

Further, by applying the STM principle as described above, a probe having conductivity with respect to a recording medium is used as an atom,
It has been proposed to realize a high-density memory by accessing and recording / reproducing on a molecular scale (Japanese Patent Laid-Open Nos. 63-161552 and 161553). Further, for a high-density memory having a device configuration in which STM and AFM are combined, recording is performed by applying a voltage between the probe and the recording medium in the STM configuration,
A recording / playback device that plays back by detecting the recording bit shape in the configuration, and a probe position control during recording and playback
A recording / reproducing device that applies the principle of M and a recording / reproducing device that makes the probe follow the surface of the recording medium during recording and reproducing by utilizing the deformation of the elastic body that supports the probe have also been proposed. (JP-A-1-245445, JP-A-4-32
1955).

[0005]

However, the above-mentioned conventional scanning probe microscope, STM and AF are used.
In an information processing apparatus such as a recording / reproducing apparatus that is a combination of M and M, since the probe is scanned in the state of being close to or in contact with the medium, frictional force may occur between the tip of the probe and the medium. Then, this frictional force may deform or destroy the medium surface during scanning of the probe. Further, there may be a case where a fragment of the medium surface generated by friction adheres to the probe tip (contamination of the probe tip). As a result, the resolution of the probe may be lowered, the conductivity of the tip of the probe may be lowered, and when this medium is a recording medium, the reliability of recording and reproducing may be lowered. Further, heat resulting from the frictional force between the probe tip and the medium surface is generated on the probe tip and the recording surface in contact with the tip. As a result, thermal drift may occur at the tip of the probe and the recording surface, which may lead to a decrease in the reliability of recording / reproduction of the sample observation image and information.

On the other hand, because of the frictional force between the probe medium surfaces,
There is a problem that the driving power of the means for driving the probe and the medium relative to each other is naturally higher than that without friction. Conventionally,
In order to reduce such frictional force, a lubricating film may be provided on the medium surface or the probe surface. However,
When a lubricating film is provided on the probe surface, there are the following problems. If it is a scanning probe microscope,
There is a problem that the lubricant film increases the radius of curvature of the probe and the distance between the probe tip and the sample surface, thus degrading the resolution of the probe. Further, if the tip of the probe is sharpened on the assumption that the lubricating film is provided, there is a problem that the mechanical strength of the probe is lowered. Further, in the case of an information recording / reproducing apparatus, whether the lubricating film is fixed on the recording medium surface or the probe surface, the distance between the recording medium surface and the probe increases due to the lubricating film, and the probe is attached to the recording medium surface. There was a problem that it would be difficult to access it directly. Further, there is a problem that electric charges may be accumulated at the interface between the lubricating film and the probe and the interface between the lubricating film and the recording medium, which may hinder the recording and reproduction of information. Further, when the lubricant film is fixed on the surface of the recording medium, there is a problem that the lubricant film may be destroyed when the probe scans the pinhole due to defects such as pinholes generated in the lubricant film. Therefore, an object of the present invention is to provide an information processing apparatus such as an information recording / reproducing apparatus and a scanning probe microscope in which a frictional force between a probe and a medium is reduced in order to solve the above problems.

[0007]

In order to achieve the above object, the present invention provides an information processing apparatus having the following features. That is, first, the information processing apparatus according to the present invention is an information processing apparatus that scans a probe with respect to a medium to perform information processing, in a state where the tip of the probe is close to or in contact with the surface of the medium. When scanning on the surface of the medium, a potential difference signal detecting means for detecting a potential difference signal generated between the probe and the medium, and an inverse potential signal with respect to the potential difference signal output from the potential difference signal detecting means are formed. Reverse potential signal forming means,
A reverse potential signal applying means for applying a reverse potential signal formed by the reverse potential signal forming means, wherein the probe and the medium are being scanned while the reverse potential signal of the reverse potential signal applying means is close to or in contact with the medium. The information processing apparatus is characterized in that the potential difference signal generated between the probe and the medium is canceled by applying the voltage between them. Secondly, the information processing apparatus relatively two-dimensionally scans the conductive probe supported by an elastic body, a recording medium provided so as to face the probe, and the probe and the recording medium. And a voltage applying means for applying a voltage for recording information between the probe and the recording medium. Thirdly, the information recording / reproducing apparatus is configured to form a recording bit on the recording medium by a recording signal of a voltage applying means applied between the probe and the recording medium. I am trying. Fourthly, the recording medium is formed of a Si wafer. Fifth, the recording medium is characterized by being formed of an Au film. Sixth, the recording bit is formed in a convex shape or a concave shape. Seventh, the information recording / reproducing apparatus includes elastic deformation amount detecting means for detecting an elastic deformation amount of a supporting elastic body of the probe generated when the probe scans the recording medium, and the elastic deformation amount detecting means. Information reproducing means for reproducing information by detecting the shape of the recording bit on the surface of the recording medium on which information is recorded, from the elastic deformation amount detection signal output from the means. It is a recording / reproducing device. Eighth, the potential difference signal detecting means outputs a signal obtained by subtracting the recording bit forming potential component from the detected potential difference signal during the formation of the recording bit to the reverse potential signal forming means. I am trying.
Ninth, the potential difference signal detecting means outputs a signal which does not subtract the recording bit forming potential component from the detected potential difference signal during the formation of the recording bit to the reverse potential signal forming means. This is an information recording / reproducing apparatus. Tenth, in the information recording / reproducing apparatus, the conductivity of the recording medium is locally changed by the voltage applied between the probe recording media, and the changed conductivity is preserved even after the voltage application. It is characterized by being configured as. Eleventh, the information recording / reproducing apparatus is characterized in that the recording medium has a recording bit area in which the conductivity locally changes. Twelfth, the recording medium is formed of a Si wafer. Thirteenth, the recorded bits are
It is characterized in that it is formed in a convex shape or a concave shape.
Fourteenth, the information recording / reproducing apparatus includes a current detecting means for detecting a value of a current flowing through the probe when a constant voltage is applied between the probe recording media and the probe is scanned over the recording medium, The present invention is characterized by further comprising information reproducing means for reproducing information by detecting the conductivity of the recording bit from the current signal detected by the current detecting means. Fifteenthly, in the information processing apparatus, the potential difference signal detecting means subtracts the constant voltage component for conductivity change detection from the potential difference signal detected during the change in conductivity to form the reverse potential signal. It is characterized by outputting to the means. Sixteenth, the information processing apparatus is a scanning probe microscope that measures the surface condition of the sample by scanning the sample for a surface condition detection probe. Seventeenth, the scanning probe microscope uses an atomic force between a probe and a sample. Eighteenth, the scanning probe microscope has a voltage applying means for applying a voltage between the probe and the sample for measuring a surface state, and a current value flowing through the probe by applying a voltage by the voltage applying means. And a current detecting means for detecting. Nineteenth, the potential difference signal detecting means subtracts the potential component applied between the probe and the sample by the voltage applying means from the detected potential difference signal during the voltage application by the voltage applying means. Is output to the reverse potential signal forming means. Twentieth, in the scanning probe microscope, when a voltage is applied between the probe and the sample by the voltage applying means, the current value flowing in the probe and the atomic force between the probe and the sample are simultaneously measured. The feature is that it is detected.

[0008]

According to the present invention, by applying the voltage between the probe and the medium, the frictional force generated when scanning is performed with the tip of the probe in the vicinity of or in contact with the medium (recording surface or sample surface) is constituted by the above structure. It is designed to be reduced. The principle of the method of electrically controlling the frictional force in this way has been reported by Yoshio Yamamoto [Technical Research Report of the Institute of Electronics, Information and Communication Engineers (EMC). Vo1.91, no. 27
1, 1991]. The above report shows that when a metal rod and a ring are rubbed together, an electric signal is externally applied so as to cancel the potential difference generated between the two metals, and the frictional force generated between the two objects can be reduced. Is reported. The present invention is an information recording / reproducing apparatus that scans such a method for reducing the electric frictional force in a state where the probe tip is close to or in contact with a medium (recording surface or sample surface) or an information processing apparatus such as a scanning probe microscope. It is used to reduce the frictional force generated between the probe and the medium.

The details will be described below with reference to the drawings. In FIG. 1, 101 is a conductive probe,
102 is a cantilever for supporting the probe 101,
3 is the tip of the probe, 104 is the medium (recording medium / sample), and 105 is the recording surface or sample surface. 10
6, the probe tip 103 has a recording surface or a sample surface 105.
It is a potential difference signal detecting means for detecting a potential difference signal generated between the probe 101 and the medium 104 when both are relatively scanned while being in contact with. 107 is a reverse potential signal forming means for forming a reverse potential signal for the potential difference signal output from the potential difference signal detecting means 106. Reference numeral 108 denotes the probe 101 which is relatively scanning the reverse potential signal formed by the reverse potential signal forming means 107 while being in contact with each other.
And a reverse potential signal applying means for applying between the medium and the medium 104. The reverse potential signal from the reverse potential signal applying means 108 is
The probe 101 and the medium 104 are arranged so as to cancel the potential difference signal generated between the probe 101 and the medium 104.
Applied between. As described above, according to the present invention, the frictional force generated between the probe tip 103 and the recording surface or the sample surface 105 is reduced by reducing the potential difference generated during the dynamic friction generation process. The process of reducing the frictional force will be schematically described with reference to FIG. 2 from the viewpoint of signal processing. Set the probe tip 103 to the recording surface or the sample surface 10
It is assumed that scanning is performed by contacting with 5. At that time, the potential difference signal detection means 106 detects the potential difference signal ΔV as a function of the time t as schematically shown in FIG. Figure 2
T1 and t2 in (a) indicate arbitrary times during scanning. V1 and V2 are potential difference values at times t1 and t2, respectively. The reverse potential signal forming means 107 sequentially forms the reverse potential signal ΔVg (see FIG. 2B) for the potential difference signal ΔV from the potential difference signal detecting means 106. Therefore, the signal values of ΔV and ΔVg at arbitrary times have substantially the same magnitude and opposite polarities. Figure 2
The reverse potential signal values near times t1 and t2 in (b) are approximately -V1 and -V2, respectively.

The reverse potential signal applying means 108 uses the reverse potential ΔVg as the probe 101 so as to reduce the potential difference ΔV generated between the probe 101 and the recording medium 104 based on the signal from the reverse potential signal forming means 106. It is applied between the recording media 104. The probe 101 and the recording medium 1 when the reverse potential signal is applied by the reverse potential signal applying means 108.
The potential difference signal ΔVm apparently generated during 03 is
It is V + ΔVg. As mentioned above, ΔV at any time
g has the same size as ΔV and the sign is opposite. Therefore, the apparent potential difference signal ΔVm can be set to 0 in principle. Temporarily from time 0 to time t2, the probe 101
When the reverse potential signal is not applied between the medium and the medium 104,
If the reverse potential signal is applied after 2, the apparent potential difference signal Δ between the probe 101 and the medium 104 after time t2.
The intensity of Vm is reduced (see FIG. 2 (c)). As the apparent potential difference signal ΔVm decreases, the probe 10
It is possible to reduce the magnitude f of the frictional force generated between the medium 1 and the medium 104 (see FIG. 2D). The friction force between the probe and the recording surface is measured by an atomic force microscope (AF
It can be carried out by a known method applying the principle of M).
That is, the probe 101 is attached to the recording surface or the sample surface 105.
When scanned above, the cantilever 102 deforms according to the surface form of the recording surface and the frictional force. For example, assume that the probe is scanned in a direction perpendicular to the main axis direction of the cantilever. In this case, the deformation of the cantilever depending on the surface morphology is mainly in the direction perpendicular to the recording surface. On the other hand, the deformation of the cantilever according to the frictional force is mainly in the direction of twisting the cantilever around its main axis. The deformation (torsion of the cantilever) caused by this frictional force can be measured by irradiating the semiconductor laser 109 with laser light from behind the cantilever and detecting the reflected light from the cantilever with the four-division optical sensor 110. . The reason why the frictional force is reduced by reducing the potential difference between the probe and the recording medium by applying the reverse potential has not yet been clarified.

[0011]

Embodiments of the present invention will be described below. [Embodiment 1] FIG. 3 is a block diagram of an information recording / reproducing apparatus according to Embodiment 1 of the present invention. In the present embodiment, the friction force generated between the probe and the recording surface when the probe is brought into contact with the recording surface on which the recording bit is not formed and is scanned without performing the recording / reproducing operation can reduce the friction force in the present invention. It was reduced by the method. In FIG. 3, reference numeral 301 denotes a conductive probe, which is made of W. 302 is the tip of the probe. The probe 301 is fixed to the free end of the cantilever 303. 304a is a disk-shaped recording medium, and 305a is a recording surface. The recording surface 305a faces the probe tip 302. In this example, an epitaxially grown Si wafer was used as the recording medium 304a. A recording medium support base 306a supports and fixes the recording medium 304a. 307a is a recording medium support 306a
Is a z-direction driving means for driving in the z-axis direction shown in FIG. 3, and is capable of fine movement and coarse movement. The z-axis is the recording surface 305.
It is parallel to the normal direction of a. The x axis and the y axis are parallel to the recording surface 305a. The z-direction driving means 307a adjusts the interval between the tip 302 of the probe and the recording surface 305a. Three
Reference numeral 08a denotes a rotating unit that rotates the recording medium 304a in the xy plane by rotating the z-direction driving unit 307a, and is capable of coarse and fine movements. Recording medium 304a
The rotation axis at the time of rotation passes through the center of the circle of the circular recording surface 302 and is parallel to the z-axis. Reference numeral 309a is a drive means for driving the cantilever in the x and y axis directions, and is capable of coarse and fine movements. Reference numeral 314a is a vibration isolation table of the information recording / reproducing apparatus of this embodiment. In FIG. 3, the vibration isolation table 309a supports the rotating means 308a, but also performs vibration isolation on the cantilever 303. Reference numeral 310 denotes a potential difference signal detection unit that detects a potential difference signal generated between the probe 301 and the recording medium 304a when the recording surface 305a is scanned while the probe tip 302 is in contact with the recording surface 305a. Reference numeral 311 is a reverse potential signal forming means for forming a reverse potential signal with respect to the potential difference signal output from the potential difference signal detecting means 310. 312 is a reverse potential signal forming means 31.
It is a reverse potential signal applying means for applying the reverse potential signal formed in 1 between the probe 301 and the recording medium 304a which are relatively scanning while being in contact with each other.

In this embodiment, the recording surface 305a is brought into contact with the probe tip 302 by the z-direction driving means 307a, and the recording medium 304a is rotated by the rotating means 308a. At this time, a frictional force is generated between the probe tip 302 and the recording surface 305a. In this example, this frictional force was reduced by the method described above with reference to FIGS. 1 and 2. It is assumed that the probe tip 302 is brought into contact with the recording surface 305a for scanning. At that time, the potential difference signal detecting means 310
Detects the potential difference signal ΔV as a function of time t as shown in FIG. Note that t1 and t2 in FIG. 2A indicate arbitrary times during scanning. V1 and V2 are potential difference values at times t1 and t2, respectively. The reverse potential signal forming means 311 uses the potential difference signal detecting means 310.
The reverse potential signal ΔVg (FIG. 2) to the potential difference signal ΔV from
(See (b)) are sequentially formed. Therefore, the signal values of ΔV and ΔVg at arbitrary times have substantially the same magnitude and opposite polarities. For example, the times t1 and t in FIG.
The reverse potential signal values near 2 are approximately -V1 and -V2, respectively.
Becomes The reverse potential signal applying means 312 applies the reverse potential ΔVg to the probe 301 and the recording medium 304a so as to reduce the potential difference ΔV generated between the probe 301 and the recording medium 304a based on the signal from the reverse potential signal forming means 311. Applied between and. The potential difference signal ΔVm apparently generated between the probe 301 and the recording medium 304a when the reverse potential signal is applied by the reverse potential signal applying means 312.
Is ΔV + ΔVg. As described above, ΔVg at an arbitrary time has substantially the same magnitude as ΔV and the sign is opposite. Therefore, the apparent potential difference signal ΔVm can be set to 0 in principle. The size of the epitaxially grown Si wafer used in this example is 2 inches, and the crystal axis of the plane is (111). The substrate Si was an Sb-doped n type and had a resistivity of 0.01 Ω · cm. Substrate Si
The epitaxial layer Si grown on it was P-doped n-type and had a resistivity of 5 Ω · cm. This Si wafer is dipped in a 10% HF solution for 5 seconds to remove the native oxide film on the surface.
By performing this treatment, the dangling bond of Si exposed on the Si surface is terminated by H (hydrogen), and S
It has been found that the i surface creates a stable structure that is not readily oxidized in the atmosphere. When the thickness of the oxide film is large, a sufficient current does not flow during recording, which causes a problem of unstable recording, and it is desirable to perform this process. The (111) -axis epitaxially grown Si wafer is used here because it is used for other Si wafers ((100) -axis wafer and F
This is because the surface flatness at the level of the size of the recording bit after the HF treatment is better than that of a wafer manufactured by the Z method or the CZ method).

Further, the measurement of the frictional force between the probe and the recording surface was carried out by a known method applying the principle of the atomic force microscope (AFM) described above. That is, when the probe 301 is scanned on the recording surface 305, the cantilever 303 deforms according to the surface form of the recording surface 305a and the frictional force. It is assumed that the probe 301 is scanned in a direction perpendicular to the main axis direction of the cantilever 303. In this case, the deformation of the cantilever 303 depending on the surface form is mainly in the direction perpendicular to the recording surface 305a. On the other hand, the deformation of the cantilever 303 depending on the frictional force is mainly in the direction of twisting the cantilever 303 around its main axis. The deformation (torsion of the cantilever) caused by this frictional force is generated by irradiating the semiconductor laser 316 with laser light from behind the cantilever 303,
Light sensor 3 that divides the reflected light from the cantilever 303 into four
It can be measured by detecting at 17. The computer 3 controls the signal output of the reverse potential signal applying means 312.
13 was performed. The reverse potential signal was not applied between the probe 301 and the recording medium 304a from time 0 to time t2, and the reverse potential signal was applied after time t2. As a result, after time t2, the intensity of the apparent potential difference signal ΔVm between the probe 301 and the recording medium 304a was reduced (FIG. 2C).
reference). As the magnitude of the apparent potential difference signal ΔVm decreases, the magnitude f of the frictional force generated between the probe 301 and the recording medium 304a can be reduced (FIG. 2).
(See (d)). Incidentally, reference numeral 315 in FIG. 3 is a voltage applying means having a function of applying a voltage between the probe and the recording medium in order to form a recording bit on the recording surface. The formation of recording bits will be described in the second embodiment.

[Embodiment 2] In this embodiment, an apparatus having exactly the same structure as the information recording / reproducing apparatus (see FIG. 3) used in Embodiment 1 is used. Then, the friction force generated between the probe and the recording surface during the writing of information on the surface of the epitaxial Si wafer which is the disk-type recording medium 304a and the reproducing operation of the written information is performed by the method for reducing the frictional force according to the present invention. Reduced. In the present embodiment, the recording surface 305a is z
The probe tip 302 is brought into contact with the direction driving means 307, and the recording medium 304a is rotated by the rotating means 308a. Then, while rotating the recording medium 304a, a recording bit is formed on the recording surface 305a and a recording bit reproducing operation is performed.

Here, the principle of recording performed in this embodiment will be described. Recording of information is performed in the atmosphere, and the recording surface 305
The probe tip 302 is brought into contact with a and the recording medium 304
A voltage is applied between a and the probe 301. In this embodiment, the recording surface is covered with a natural oxide film of Si having a thickness of several atomic layers on the surface. However, when a current flows in the portion in contact with the probe tip, the recording surface is generated by Joule heat. The oxidation is locally promoted at. Due to such local oxidation, the substance forming the recording medium further takes in oxygen from the atmosphere, the thickness of the oxide film increases, and the volume increases, so that the surface shape locally changes to be convex. , Form recording bits. In this embodiment, the probe tip 302 is brought into contact with a desired position on the recording surface 305a, and the voltage applying means 3 is applied.
When a voltage pulse of 4 V and 10 μs was applied between the probe and the recording medium by 15, the height was 1 nm and the diameter was 30 nm.
The recording bits having a convex shape were formed with good reproducibility (the method of detecting the shape of the recording bits, that is, the reproducing method of the recording bits will be described later). It was possible to change the height and diameter of the recording bit by changing the peak value and time width of the applied voltage pulse. For example, 4V, 100
For ms voltage pulse, height 10 nm, diameter 100 nm
Recording bits were formed. However, the peak value is preferably in the range of 2 to 5V. The handling of the potential difference signal detected by the potential difference signal detecting means 310 during the recording bit forming operation will be described later. Next, the principle of reproducing the written convex recording bits in the atmosphere will be described. In this embodiment, the convex shape is detected by using the principle of AFM. Specifically, the probe tip 302 is connected to the recording surface 30.
When the probe tip 302 scans on the convex recording bit when the probe 5a is contacted and scanned, the probe 301
The cantilever 303 that supports the flexure. The deflection amount of this cantilever is detected by an optical lever method. That is, laser light is emitted from the semiconductor laser 316 from behind the cantilever 303, and the amount of positional deviation of the reflected light spot is obtained. The amount of displacement of this reflected light spot is 4
It is detected by the split light sensor 317. Then, the output from the four-division optical sensor 317 is used as a reproduction signal. In addition, as a means for detecting the deflection amount of the probe 303, a probe deflection amount detection means such as an optical detection means such as an optical wave interferometer or an electrical detection means such as a piezoelectric sensor or a strain resistance sensor may be used as the probe. It is also possible to use one integrated with the above.

A method for reducing the frictional force generated between the probe tip and the recording surface during the reproducing operation of the information recording bit and the recording bit forming operation by the frictional force reducing operation according to the present invention will be described below. Further, the same method as described in Example 1 was used for measuring the frictional force. The method of reducing the frictional force during the recording bit reproducing operation was the same as that described in the first embodiment. That is, the potential difference signal detecting means 310 detects the potential difference signal generated between the probe and the recording medium. Next, a reverse potential signal for the potential difference signal is formed by the reverse potential signal forming means 311. Then, the reverse potential signal applying means 312 applied a reverse potential signal between the probe and the recording medium so as to cancel the potential difference signal generated between the probe and the recording medium. As a result, it was possible to reduce the frictional force generated between the probe tip and the recording surface during the reproducing operation of the recording bit. Next, the method of reducing the frictional force generated between the probe and the recording surface during the recording bit forming operation differs from that during the recording bit reproducing operation in the following points. During the formation of the recording bit, the potential difference signal detecting means 310.
Is a signal obtained by subtracting the potential signal component for forming the recording bit from the detected potential difference signal, the reverse potential signal forming means 31.
Output to 1.

A more detailed method of reducing the frictional force during the recording bit forming operation will be described with reference to FIGS. 3 and 4. FIG. 4A schematically shows an example of the time change of the output voltage Vw of the voltage applying unit 315. In FIG. 4A, the output voltage Vw = 0 from time 0 to time t1, the pulse width = (t3-t1) from time t1 and the rectangular wave for recording bit formation of Vw = Vo are output, and the probe is used. -The rectangular wave is applied between recording media. FIG. 4B shows a time change of the potential difference signal ΔV input to the potential difference signal detecting means 310. From time 0 to time t1, the potential difference signal mainly due to only the frictional force between the probe and the recording surface is input to the potential difference signal detecting means 310. However, from time t1 to time t3, a signal obtained by adding the signal of the recording bit forming voltage to the potential difference signal caused by the frictional force between the probe and the recording surface is input to the potential difference signal detecting means 310. In the present invention, during the recording bit forming operation, the potential difference signal detecting means 310 outputs a signal obtained by subtracting the recording bit forming voltage signal component from the input potential difference signal to the reverse potential signal forming means 311. FIG. 4C shows the signal Δv output by the potential difference signal detection means 310. From time 0 to time t1, the signal input to the potential difference signal detection means 310 is output. However, during the period from time t1 to time t3, a signal obtained by subtracting the recording bit forming voltage signal component from the signal input to the potential difference signal detecting means 310 is output. That is, from time t1 to time t3, Δv = ΔV−Vo.
This subtraction process is performed under the control of the computer 313. FIG. 4D shows the reverse potential signal output by the reverse potential signal forming means 311 based on the signal from the potential difference signal detecting means 310. In this embodiment, the reverse potential signal applying means 312 does not apply the reverse potential signal based on the signal from the reverse potential signal forming means 311 between the probe and the recording medium until the time t2 during the recording bit forming operation, and after the time t2. Applied to. As a result, after time t2, the intensity of the apparent potential difference signal ΔVm between the probe 301 and the recording medium 304a decreased (see FIG. 4 (e)). Apparent potential difference signal ΔVm
Probe 301 and recording medium 3 as the size of the probe decreases.
It was possible to reduce the magnitude f of the frictional force generated during 04a (see FIG. 4 (f)). Note that the waveform of the recording bit forming voltage is not limited to the rectangular wave, and any waveform such as a triangular wave may be used as long as recording can be performed.

[Embodiment 3] In the information recording / reproducing apparatus of this embodiment, an Au thin film is used as a recording medium, and the tip of the probe is made of W. The structure of the information recording / reproducing apparatus is the same as that of the first and second embodiments. The recording bit formation in this embodiment was performed by bringing the probe tip 302 into contact with a desired position on the recording surface 305a and applying a voltage pulse between the probe and the recording medium by the voltage applying means 315. As a result, recording bits having a convex shape with a height and a diameter on the order of nm were formed with good reproducibility. By changing the peak value and the time width of the applied voltage pulse for recording, the height and diameter of the recording bit can be changed. It is also possible to make the shape of the recording bit concave. The principle of reproducing the written recording bit in the atmosphere is the same as that of the first embodiment, and the recording bit was detected using the principle of AFM. In this embodiment, in order to reduce the frictional force generated between the probe tip and the recording surface during the reproduction and recording operations of the information recording bit, the same operation as the frictional force reducing operation described in the second embodiment was performed. As a result, it was possible to reduce the frictional force generated between the probe tip and the recording surface during the reproduction of the recording bit and the recording operation.

[Embodiment 4] In this embodiment, an apparatus having exactly the same configuration as the information recording / reproducing apparatus used in Embodiment 2 was used.
Then, except for the following signal processing, the same operation as in Example 2 was performed to reduce the frictional force generated between the probe tip and the recording surface during the recording / reproducing operation. The signal processing different from that of the second embodiment is that the potential difference signal detecting means 310 outputs the input signal to the reverse potential forming means 311 without subtracting the recording bit forming voltage signal component from the inputted potential difference signal during the recording bit recording operation. It is to let. The reason for performing such signal processing is that the recording bit forming voltage value is large with respect to the potential difference caused by the frictional force generated between the probe tip and the recording surface. That is, when the recording bit forming voltage is applied between the probe and the recording medium, the potential difference signal detecting means 31.
This is because the main component of the potential difference signal detected by 0 is almost the voltage signal for forming the recording bit. As a result of the above signal processing, the frictional force generated between the probe tip and the recording surface during the recording bit reproducing operation could be reduced.

[Embodiment 5] FIG. 5 is a block diagram of an information recording / reproducing apparatus according to the present invention. The configuration of the device is the same as that of the second embodiment except that the current-voltage conversion circuit 318a is incorporated as shown in FIG. The current-voltage conversion circuit 318a is used when reproducing recorded bits (details will be described later). The method of forming recording bits in this embodiment is the same as that in the second embodiment. That is, the probe tip 302 is brought into contact with a desired position of the recording surface 305a of the recording medium (Si wafer) 304a, and a recording voltage pulse is applied between the probe and the recording medium by the recording voltage applying means 315 (details will be described). See Example 2). On the other hand, in the present example, the reproduction of the written recording bits was performed electrically as follows. First, a constant voltage is applied between the probe and the recording medium by the voltage applying unit 315 to move the probe 301 to the recording surface 305a.
Scan over. At that time, a minute current flowing through the probe 301 is converted into a voltage by the current-voltage conversion circuit 318a and detected. The recording bit has a convex shape as described above and is made of an oxide of Si. Therefore,
The conductivity in the normal direction of the recording surface of the recording medium is smaller (the electrical resistance is larger) in the recording bit area than in the portion where the recording bit is not formed. Therefore, the recorded bits can be reproduced based on the magnitude of the current value detected by the current-voltage conversion circuit 318a.

In this embodiment, in order to reduce the frictional force generated between the probe tip and the recording surface during the operation of forming the information recording bit, the same operation as the frictional force reduction scanning described in the second embodiment is performed. . That is, basically, during the recording bit forming operation, the potential difference signal detecting means 310 detects the potential difference signal generated between the probe and the recording medium. Next, a reverse potential signal for the potential difference signal is formed by the reverse potential signal forming means 311. Then, by the reverse potential signal applying means 312,
A reverse potential signal is applied between the probe and the recording medium so as to cancel the potential difference signal generated between the probe and the recording medium. However, the potential difference signal detecting means 310 is provided only when the recording bit forming voltage is applied between the probe recording media.
The potential difference signal detection means 310 outputs to the reverse potential formation means 311 a signal obtained by subtracting the recording bit formation voltage signal component from the signal detected by. As a result, it was possible to reduce the frictional force generated between the probe tip and the recording surface during the recording bit forming operation. On the other hand, in this embodiment, in order to reduce the frictional force generated between the probe tip and the recording surface even during the recording bit reproducing operation, the same signal processing as that during the recording bit formation is performed to perform the frictional force reduction operation. . That is, the potential difference signal detection means 310 subtracts a signal obtained by subtracting the recording bit reproduction voltage signal component from the signal detected by the potential difference signal detection means 310 only at the timing when the recording bit reproduction voltage is applied between the probe and the recording medium. Forming means 311
Output to. Next, a reverse potential signal for the potential difference signal is formed by the reverse potential signal forming means 311. Then, the reverse potential signal applying means 312 applies a reverse potential signal between the probe and the recording medium so as to cancel the potential difference signal generated between the probe and the recording medium. As a result, it was possible to reduce the frictional force generated between the probe tip and the recording surface during the recording bit reproducing operation. The material structure of the recording medium and the probe, and the recording / reproducing method are not limited to those in the above embodiment.

[Embodiment 6] FIG. 6 is a block diagram of a scanning atomic force microscope according to the present invention. In this example, the height of the probe from the sample support was kept constant and the sample surface was scanned to observe the irregularities on the sample surface. The frictional force generated between the probe and the sample surface during the scanning of the probe was reduced by the frictional force reduction method according to the present invention. In FIG. 6, reference numeral 301 denotes a conductive probe, which is made of W in this embodiment. 302 is the tip of the probe. The probe 301 is fixed to the free end of the cantilever 303. 304b is a sample and 305b is a sample surface. The sample surface 305b faces the probe tip 302. In this example, an epitaxially grown Si wafer was used as the sample 304b. 306b is a sample support base that supports and fixes the sample 304b. Reference numeral 307b denotes a z-direction driving unit that drives the sample support base 306b in the z-axis direction shown in FIG. 6, and is capable of fine and coarse movements. The z axis is parallel to the normal line direction of the sample surface 305b. Also, x-axis, y
The axis is parallel to the sample surface 305b. z-direction driving means 3
07b adjusts the distance between the probe tip 302 and the sample surface 305b. 308b is the z-direction driving means 307b x
-Sample 2 is driven by two-dimensional driving parallel to the y-plane.
This is a two-dimensional driving means for moving 04b in the xy plane, and is capable of coarse and fine movements. Reference numeral 309b is a driving means for driving the cantilever in the x and y axis directions, and is capable of coarse and fine movements. Reference numeral 314b is an anti-vibration table of the scanning probe microscope of this embodiment. In FIG. 6, the vibration isolation table 314b supports the rotation means 308b, but the cantilever 303
We are also performing vibration isolation for. Reference numeral 313 is a computer having a device control and an image processing function. An image display unit 319 displays an observation image of the sample surface. Three
Reference numeral 10 denotes a potential difference signal detecting means for detecting a potential difference signal generated between the probe 301 and the sample 304b when scanning the sample surface 305b with the probe tip 302 being close to the sample surface 305b. Reference numeral 311 is a reverse potential signal forming means for forming a reverse potential signal with respect to the potential difference signal output from the potential difference signal detecting means 310. 31
Reference numeral 2 denotes a probe 3 which is relatively scanning the reverse potential signal formed by the reverse potential signal forming means 311 in a state where they are close to each other.
01 is a reverse potential signal applying means applied between the sample 01 and the sample 304b. In this embodiment, in the process of observing the sample surface by two-dimensionally scanning the sample surface with the probe, the probe-
Regarding the frictional force acting between the sample surfaces, the frictional force was reduced by the same method as in Example 1. Then, the same result as in Example 1 shown in FIG. 2 was obtained.

[Embodiment 7] In this embodiment, the unevenness of the sample surface was observed in the AFM mode based on the atomic force between the probe tip and the sample surface, and at the same time, the conductivity distribution of the sample surface was observed. In order to observe the conductivity, a constant voltage was applied between the probe and the sample, and the current flowing between the probe and the sample was measured. The distribution of this current value on the sample surface corresponds to the conductivity distribution on the sample surface. Therefore, in this example, the frictional force generated between the probe tip and the sample surface was reduced in the process of scanning the probe on the sample surface while simultaneously measuring the surface unevenness image and the current image of the sample. FIG. 7 shows a configuration diagram of the scanning probe microscope used in this example. Reference numeral 315 shown in FIG. 7 is a voltage applying means for applying a voltage between the probe and the sample. The voltage applying means 315 is different from the reverse potential signal applying means 312. Reference numeral 318b is a current detection unit that detects the value of the current flowing through the probe when a voltage is applied between the probe and the sample by the voltage application unit 315. In this example, an epitaxially grown Si wafer was used as an observation sample. The crystal axis of the observation plane is (111). The substrate Si is an Sb-doped n type, and the substrate S
The epilayer Si grown on i is P-doped n-type. Immerse this Si wafer in a 10% HF solution for 5 seconds,
Remove the native oxide film on the surface. By performing this treatment, the dangling bond of Si exposed on the Si surface becomes H
It is known that it is terminated with (hydrogen) and the Si surface forms a stable structure that is not easily oxidized in the atmosphere immediately. If the thickness of the oxide film is large, a sufficient current will not flow during observation, so this treatment is desirable.

Hereinafter, the frictional force generated between the probe tip and the sample in the process of observing the unevenness image of the sample surface while applying the voltage between the probe and the sample by the voltage applying means 315 is reduced by the frictional force reducing operation according to the present invention. The method of doing is explained. The frictional force was measured by the same method as described in Example 6. As in Example 6, the method of reducing the frictional force generated between the probe tip and the sample surface in the case where the sample unevenness observation and the sample conductivity measurement were performed in parallel was performed by observing only the sample unevenness as in Example 6. The following points are different from the case. When the voltage for measuring conductivity is applied between the probe and the sample by the voltage applying means 315, the potential difference signal detecting means 310 is a signal obtained by subtracting the potential signal component for measuring conductivity from the detected potential difference signal. Is output to the reverse potential signal forming means 311 for signal processing.

A more detailed description of the above signal processing will be given with reference to FIGS. 4 and 7. FIG. 4A schematically shows an example of the time change of the output voltage Vw of the voltage applying unit 315. In FIG. 4A, a constant voltage for conductivity measurement is output from the probe-sample between the time 0 and the time t1 and the output voltage Vw = 0, and between the time t1 and the time t3, the output voltage Vw = Vo. The constant voltage was applied between the media. FIG. 4B shows the potential difference signal ΔV input to the potential difference signal detecting means 310.
Shows the change over time. From time 0 to time t1, the potential difference signal mainly due to only the frictional force between the probe and the sample surface is input to the potential difference signal detecting means 310. But,
From time t1 to t3, a signal obtained by adding the signal of the voltage for measuring the conductivity of the sample to the signal of the potential difference due to the frictional force between the probe and the sample surface is input to the potential difference signal detecting means 310. In the present invention, during the conductivity measuring operation, the potential difference signal detecting means 310 outputs a signal obtained by subtracting the conductivity measuring voltage signal component from the inputted potential difference signal to the reverse potential signal forming means 311. FIG. 4C shows the signal Δv output by the potential difference signal detection means 310. Time 0 to time t1
During the period, the signal input to the potential difference signal detection means 310 is output. However, from time t1 to time t3, a signal obtained by subtracting the conductivity measuring voltage signal component from the signal input to the potential difference signal detecting means 310 is output. That is, from time t1 to time t3, Δv = ΔV−Vo. This subtraction process is performed under the control of the computer 313. FIG. 4D shows the reverse potential signal output by the reverse potential signal forming means 311 based on the signal from the potential difference signal detecting means 310. In this embodiment, the reverse potential signal applying means 312 is operated at the time t2 (t1 during the conductivity measurement operation of the sample).
Until <t2 <t3), the reverse potential signal based on the signal from the reverse potential signal forming unit 311 was not applied between the probe and the sample medium, but was applied after the time t2. As a result, after time t2, the intensity of the apparent potential difference signal ΔVm between the probe 301 and the sample medium 304b decreased (see FIG. 4 (e)).
It was possible to reduce the magnitude f of the frictional force generated between the probe 301 and the sample medium 304b as the magnitude of the apparent potential difference signal ΔVm decreased (see FIG. 4 (f)).

[Embodiment 8] In this embodiment, an apparatus having the same structure as the scanning probe microscope (see FIG. 7) used in Embodiment 7 was used. Then, in this example, an Au thin film was used as the sample medium as the sample 304b. In this example, the unevenness of the surface of the sample and the conductivity of the sample were measured in parallel.
Then, at this time, it was attempted to reduce the frictional force generated between the probe tip and the sample surface by the same operation as described in Example 7. As a result, in the process of observing the unevenness of the sample surface and measuring the conductivity of the sample in parallel, the probe tip-
The frictional force generated between the sample surfaces could be reduced. The material structure of the probe and the voltage waveform for measuring the conductivity are not limited to those in the above embodiment. In addition to the above, the present invention replaces the probe in the AFM with a ferromagnetic substance of Fe or Ni, or a probe made of any of these materials and coats the probe, instead of scanning for measuring the local magnetic force on the sample. It can be applied to a magnetic force microscope (MFM). Also, using an optical probe having a pinhole with a diameter smaller than the wavelength of light (coated except for the pinhole part with a conductive substance), the evanescent light generated on the sample surface when the sample is irradiated by an external light source. Is also applicable to a scanning near-field optical microscope (NSOM) or the like in which the surface structure of a sample is detected by detecting the.

[0027]

As described above, according to the present invention, the probe tip is a medium (recording surface or sample surface) in the information processing apparatus.
The frictional force generated when scanning in the vicinity of or in contact with the probe is reduced by applying a voltage between the probe and the medium, and the tip of the probe or the medium surface is deformed or destroyed during scanning of the probe. It is possible to prevent contamination of the probe tip. Further, according to the present invention,
Since the frictional force can be reduced without depending on the lubricating film, when an information recording / reproducing device or an information processing device such as a scanning probe microscope is configured by this, the friction between the probe tip and the medium surface is reduced. Generation of heat due to force and thermal drift of the probe tip and recording surface can be suppressed, the resolution of the probe and the reliability of recording and reproduction can be improved, and power consumption can be significantly reduced. it can.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of means for electrically reducing frictional force.

FIG. 2 is a diagram for explaining the principle of electrically reducing frictional force.

FIG. 3 is a schematic diagram of an information recording / reproducing apparatus of Examples 1, 2, 3, and 4.

FIG. 4 is a diagram showing a principle of electrically reducing a frictional force during recording / sample and / or reproduction.

FIG. 5 is a schematic diagram of an information recording / reproducing apparatus according to a fifth embodiment.

FIG. 6 is a schematic diagram of a scanning probe microscope of Example 6.

FIG. 7 is a schematic diagram of a scanning probe microscope of Example 7.

[Explanation of symbols]

 101, 301 probe 102, 303 cantilever 103, 302 probe tip 104 medium 304a recording medium 304b sample medium 105 medium surface 305a recording surface 305b sample surface 106, 310 potential difference signal detecting means 107, 311 reverse potential signal forming means 108, 312 reverse potential Signal applying means 313 Computer 314a Slow shaking table of information recording / reproducing apparatus 314b Slow shaking table of microscope 315 Voltage applying means 316 Semiconductor laser 317 Four-division optical sensor 318a Current-voltage conversion circuit 318b Current detecting device

Claims (20)

[Claims] 1. An information processing apparatus which scans a medium with a probe to perform information processing, when the tip of the probe scans the surface of the medium in a state of being close to or in contact with the surface of the medium. A potential difference signal detecting means for detecting a potential difference signal generated between the probe and the medium; a reverse potential signal forming means for forming a reverse potential signal with respect to the potential difference signal output from the potential difference signal detecting means; A reverse potential signal applying means for applying a reverse potential signal formed by the signal forming means, and the reverse potential signal of the reverse potential signal applying means is applied between the probe and the medium being scanned in a state of being close to or in contact with the medium. Then, the information processing apparatus is configured to cancel the potential difference signal generated between the probe and the medium. 2. The information processing apparatus comprises a probe, a recording medium provided so as to face the probe, a means for relatively two-dimensionally scanning the probe and the recording medium, and information recording. 2. The information processing apparatus according to claim 1, which is an information recording / reproducing apparatus having a voltage applying unit that applies the voltage of 2 between the probe and the recording medium. 3. The information recording / reproducing apparatus according to claim 2, wherein the information recording / reproducing apparatus records a bit on a recording medium by a recording signal of a voltage applying means applied between the probe and the recording medium. An information recording / reproducing apparatus, which is configured to form a. 4. The information recording / reproducing apparatus according to claim 3, wherein the recording medium is formed of a Si wafer. 5. The information recording / reproducing apparatus according to claim 3, wherein the recording medium is formed of an Au film. 6. The information recording / reproducing apparatus according to claim 3, wherein the recording bit is formed in a convex shape or a concave shape. 7. The information recording / reproducing apparatus according to claim 3, wherein an elastic deformation amount of a supporting elastic body of the probe generated when the probe scans the recording medium. Of the information by detecting the shape of the recording bit on the surface of the recording medium on which the information is recorded, from the elastic deformation amount detecting means for detecting the elastic deformation amount detecting signal and the elastic deformation amount detecting signal output from the elastic deformation amount detecting means. An information recording / reproducing apparatus comprising: an information reproducing means for reproducing. 8. The potential difference signal detecting means outputs a signal obtained by subtracting a recording bit forming potential component from the detected potential difference signal during formation of the recording bit to the reverse potential signal forming means. Claim 3 characterized by
The information recording / reproducing apparatus described in. 9. The potential difference signal detecting means outputs, to the reverse potential signal forming means, a signal that does not subtract the potential component for recording bit formation from the detected potential difference signal during formation of the recording bit. The information recording / reproducing apparatus according to claim 3, which is characterized in that. 10. The information recording / reproducing apparatus according to claim 2, wherein the recording medium has its conductivity locally changed by a voltage applied between the probe recording media, and the conductivity after the change is changed. An information recording / reproducing apparatus, wherein the information recording / reproducing apparatus is configured to be stored even after the voltage is applied. 11. The information recording / reproducing apparatus according to claim 10, wherein the recording medium has a recording bit area in which the conductivity locally changes. 12. The information recording / reproducing apparatus according to claim 10, wherein the recording medium is formed of a Si wafer. 13. The information recording / reproducing apparatus according to claim 10, wherein the recording bit is formed in a convex shape or a concave shape. 14. The information recording / reproducing apparatus according to claim 10, wherein when a constant voltage is applied between the probe and a recording medium to scan the recording medium with the probe, a current value flowing through the probe is measured. Information having a current detecting means for detecting and an information reproducing means for reproducing information by detecting the conductivity of the recording bit from the current signal detected by the current detecting means. Recording / playback device. 15. The information recording / reproducing apparatus according to claim 14, wherein the potential difference signal detecting means subtracts the constant voltage component for detecting the conductivity change from the detected potential difference signal during the detection of the change in the conductivity. An information recording / reproducing apparatus, which is configured to output a signal to the reverse potential signal forming means. 16. The information processing apparatus according to claim 1, wherein the information processing apparatus is a scanning probe microscope that scans a probe for surface state detection on the sample to measure the surface state of the sample. Processing equipment. 17. The scanning probe microscope according to claim 16, wherein the scanning probe microscope uses an atomic force between a probe and a sample. 18. The scanning probe microscope according to claim 16, wherein voltage applying means applies a voltage between the probe and the sample for measuring a surface state, and voltage is applied by the voltage applying means. A scanning probe microscope, comprising: a current detection unit that detects a value of a current flowing through the probe. 19. The potential difference signal detecting means subtracts the potential component applied between the probe and the sample by the voltage applying means from the detected potential difference signal during the voltage application by the voltage applying means. 19. The scanning probe microscope according to claim 18, wherein a signal is output to the reverse potential signal forming means. 20. The scanning probe microscope according to claim 18, wherein the scanning probe microscope has a current value flowing through the probe when a voltage is applied between the probe and the sample by the voltage applying means. And the atomic force between the probe and the sample are simultaneously detected.