JP2968613B2 - Information playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information reproducing apparatus for a large-capacity, high-density information recording medium, for example.

[0002]

2. Description of the Related Art In recent years, the recording capacity of data in a recording / reproducing apparatus tends to increase rapidly, the size of a recording unit is small, and the recording density is high. For example, in a digital audio disc using optical recording,
The size of the recording unit extends to about 1 μm 2. Behind this is the active development of memory materials, and low-cost, high-density recording media using organic thin films such as organic dyes and photopolymers have appeared.

On the other hand, recently, a scanning tunneling microscope (hereinafter abbreviated as STM) capable of directly observing the electronic structure of surface atoms of a conductor has been developed [G. Binnig et al, Helvetica Physic.
a Acta, 55 726 (1982)], making it possible to measure high resolution real space images irrespective of whether they are single crystal or amorphous, and this STM uses low power without damaging the recording medium due to current. It has observable advantages and can operate in the atmosphere and can be used for various materials, so that it is expected to be widely applied.

[0004] The STM utilizes the fact that a tunnel current flows when a voltage is applied between a probe electrode and a conductive material to approach a distance of about 1 nm. This current is very sensitive to a change in the distance between the two, and surface information in real space can be obtained by scanning the probe electrode so that the current or the average distance between the two is kept constant. At this time, the resolution in the in-plane direction is about 1 Å.

By applying the principle of the STM, it is possible to perform high-density recording / reproducing on the order of several Angstroms. In this case, the recording / reproducing method
There is a method in which recording is performed by changing the surface state of an appropriate recording layer using a high energy electromagnetic wave such as a particle beam (electron beam, ion beam) or X-ray and an energy beam such as visible light and ultraviolet light, and reproducing by STM. . Further, a material having a memory effect on the switching characteristics of voltage and current as the recording layer, for example, π
In some cases, recording / reproduction using STM is performed using a thin film layer of an electronic organic compound or chalcogen compound.

In these cases, two-dimensional scanning of the probe electrode is performed in order to control the distance between the probe electrode and the recording medium on the order of angstrom and to record and reproduce information two-dimensionally arranged on the recording medium. It is necessary to control on the order of tens of angstroms. Where S
In a recording / reproducing apparatus using a TM, a so-called multi-probe, which simultaneously operates a large number of probes as described above, is required from the viewpoint of improving the function of the system, particularly, increasing the speed. FIG. 8 shows an example of this, in which a number of probes B are arranged side by side to face a recording medium A, and each performs a recording / reproducing operation.

[0007]

In such a device,
Even if the distance between the probe electrode and the recording medium is controlled on the order of angstrom, for example, thermal drift or extraneous vibration noise may occur. It is difficult to separate from In particular, in the case of a multi-probe, since different noises are generated in the signals from the respective probes, it is difficult to separate the original information reproduction signals of the respective probes.

When only one recording / reproducing probe is used, it is conceivable that a position detecting probe is separately provided to compensate for the thermal drift and vibration noise just described above. .

An object of the present invention is to provide an information reproducing apparatus capable of optimally compensating for thermal drift and vibration noise in a multi-probe with all the probes.

[0010]

An information reproducing apparatus according to the present invention for achieving the above object reproduces information recorded on a recording medium from an output of an information probe arranged opposite to the recording medium. In the information reproducing apparatus, supported by the same support as the information probe, a plurality of distance detection probes arranged facing the recording medium, the output of the information probe, the output of each of the distance detection probes,
And calculating means for calculating data compensated for the distance variation with respect to the output of the information probe based on the positional relationship, wherein the data calculated by the calculating means is used as a reproduction signal of information recorded on the recording medium. It is characterized by outputting.

[0011]

The information reproducing apparatus having the above-described structure is used for recording and reproducing based on a positional relationship with a distance detecting probe for recording or detecting, and an information probe for recording or detecting information (hereinafter referred to as a recording and reproducing probe). The compensation amount of the probe is determined, and the distance variation is compensated from the temperature drift or external vibration.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a configuration diagram, in which an XY stage 2 is provided on an anti-vibration table 1, and a Z-direction coarse movement mechanism 3 is installed above the XY stage 2. Parallel control mechanisms 4a and 4b using a laminated piezoelectric element or the like are provided on the coarse movement mechanism 3, and a recording medium holding unit 5 and a recording medium 6 are mounted thereon. A support portion 7 is disposed above the recording medium 6, and distance detection probes 8 a and 8 b and a cantilever 9 are provided on a lower surface of the support portion 7, and a recording / reproducing probe 10 is formed at a tip of the cantilever 9. Have been.

The output of the coarse drive unit 11 is connected to the Z-direction coarse movement mechanism 3, and the output of the parallel control unit 12 is connected to the parallel control mechanisms 4a and 4b. A voltage is applied from a voltage circuit (not shown) between the recording medium 6 and the distance detection probes 8a and 8b and between the recording medium 6 and the recording / reproduction probe 10. Further, in order to detect a tunnel current flowing between the recording medium 6 and the distance detection probes 8a and 8b, these are supplied with a distance fluctuation detection tunnel current to the amplification unit 1.
3, a recording medium 6 and a recording / reproducing probe 1
In order to detect a tunnel current flowing between 0 and 0, a tunnel information amplifier 14 for detecting recorded information is connected to these. Further, the output of the feedback unit 15 is connected to the cantilever 9 for controlling the cantilever 9. Then, the microcomputer 16 controls the coarse movement driving unit 1.
1, a parallel control unit 12, a distance variation detecting tunnel current amplifying unit 13, a recorded information detecting tunnel current amplifying unit 14, and a Z-direction feedback unit 15.

In order to make the support 7 and the recording medium 6 parallel, first, when the support 7 and the recording medium 6 are first opposed to each other, one of the distance detecting probes 8a and 8b and the recording medium 6
The coarse movement mechanism 3 raises the recording medium 6 side until a tunnel current flows. Next, the parallel control mechanism 4
a and 4b to move the tunnel current between the distance detection probe 8a and the recording medium 6 and the distance detection probe 8b.
And the recording medium 6 have the same tunnel current. At this stage, the support section 7 and the recording medium 6 are parallel, and recording and reproduction of information are performed while maintaining this state.

Subsequently, in order to compensate for the influence of temperature drift or external vibration, the recording information between the recording / reproducing probe 10 on the cantilever 9 and the recording medium 6 that is feedback-controlled by the Z-direction feedback unit 15 is recorded. The difference between the tunnel current output obtained by the tunnel current amplifier 14 and the tunnel current output obtained by the distance fluctuation detection tunnel current amplifier 13 between the distance detection probes 8a and 8b and the recording medium 6 is obtained by: The value is calculated by the microcomputer 16. Then, the data obtained by the calculation is output as a reproduction signal of the information recorded on the recording medium 6.

At this time, the i-th recording / reproducing probe 1
The output of 0i is Pi, the outputs of the distance detection probes 8a and 8b are Pa and Pb, the distance between the recording and reproduction probe 10i and the center of gravity G of the entire apparatus is ri, and the distance between the centers of gravity G between the distance detection probes 8a and 8b is Assuming that ra and rb are used, the output Pi can be obtained by the following equation. Pi '= P1- (αPa · r1 / ra + βPb · ri / rb)

Here, α and β are appropriate compensation gains. By optimizing these values, it is possible to compensate both the translational motion component of the center of gravity G and the rotational motion component around the center of gravity G. Become.

FIG. 2 shows a bottom view of the supporting portion 7 and is 7 mm ×
A total of 240 cantilevers 9 each having a length of 300 μm and a width of 50 μm, each of which is 24 × 10, is provided on an Si substrate 20 having a thickness of 7 mm and a thickness of 0.5 mm. A recording / reproducing probe 10 is formed in the portion.

In manufacturing the cantilever 9, first, a Si substrate 20 having a thickness of 0.5 mm is formed on a Si substrate 20 by CVD.
An i3N4 film is formed to a thickness of 0.15 μm. The source gas used is SiH 2 Cl 2: NH 3 (1: 9), and the temperature of the substrate 20 is 800 ° C. Next, Si3 is formed by photolithography and CF4 dry etching.
N4 is patterned into a desired shape. Then, Cr
Is formed to a thickness of 0.01 μm and Au to a thickness of 0.09 μm, and is patterned by photolithography and wet etching.
AlN was added to the substrate by sputtering in an atmosphere of + N2.
A 3 μm film is formed. Further, patterning is performed by photolithography and wet etching using an Al etchant, and then the above steps are repeated to form Au / Cr-AlN-Au / Cn-AlN-Au / C on the Si substrate 20.
After forming a bimorph structure of n, amorphous SiN is deposited as a protective layer to a thickness of 0.15 μm by a CVD method. Here, after a recording / reproducing probe 10 made of W (tungsten) is formed by a vapor deposition method, Si is formed by KOH.
By removing the portion where Si3N4 does not adhere by using the anisotropic etching described above, the cantilever 9 is formed, and finally Pt coating is performed.

FIG. 3 is a cross-sectional view of the cantilever 9 formed by the above-described process, wherein reference numerals 21 and 27 denote an Si3N4 film,
Reference numerals 22, 24 and 26 denote electrodes for driving the bimorph type piezoelectric material, reference numerals 23 and 25 denote piezoelectric AlN, and reference numeral 28 denotes a Pt coating layer. The cantilever 9 has a longitudinal electrode divided into two parts, and can be driven two-dimensionally.

In this embodiment, of the 240 probes 10 on the cantilever 9 shown in FIG. 4, four of the four corners are used as distance detecting probes 8a, 8b, 8c and 8d, and the remaining probes 10 are recorded. It is used as a reproduction probe 10.

As the recording medium 6, Au formed on a glass substrate is used. A pulse voltage of several volts and several microseconds was applied between the Au thin film and the recording / reproducing probe 10 to form a convex part having a diameter of about 10 nm, thereby forming a recording bit. First, a voltage was applied to the four cantilevers 9 provided with the distance detecting probes 8a to 8d, and the tips of the probes 8a to 8d were displaced toward the recording medium 6 by about 2 μm. Next, a bias voltage of 0.1 V is applied between the probes 8a to 8d and the recording medium 6 so that the tunnel current becomes 10V.
Until the current reaches 0 pA or more, the probe 8a is
8d and the recording medium 6 were brought close to each other. At this time, it was confirmed that the tunnel current flowing through each of the distance detection probes 8a to 8d was 100 pA, 1 pA, 1 pA, and 10 pA, respectively. Next, the recording medium holding unit 5 is controlled so that the tunnel current flowing through the probes 8b to 8d becomes 100 pA.
A voltage was applied to the parallel holding mechanisms 4a and 4b provided at the four corners of the above for adjustment. At this stage, the distance between the recording / reproducing probe 10 and the recording medium 6 was adjusted to about 2 μm. In this state, the cantilever 9 is driven two-dimensionally to
The write / read of the recording bit is performed according to the above. As a result, the voltage applied to all the cantilevers 9 becomes 0.8 to 1.2.
V, it was recognized that the burden on the drive power supply and the control system was small. In addition, the effect of temperature drift is reduced to 1/10
0 or less, and the read error rate due to external vibration was reduced to 1/10 of that of the conventional example.

In a similar process, 4 × 4 = 16 cantilevers 9 and probes 10 are formed in a 3 mm × 3 mm substrate 20 as shown in FIG. 8a to 8d, the remaining probes are used as recording / reproducing probes 10, and the recording medium 6 is also used in the first embodiment.
The same one as described above was used. In the same manner as in the previous embodiment, the recording bit is written while maintaining the parallelism between the support portion 7 and the recording medium 6, and at the time of reading, for example, the output of the probe 10p is set to P and the outputs of the probes 8a to 8d are set. The Pa ~ Pd
The output P 'compensated for the effects of thermal drift and vibration
Can be obtained by the following equation.

P ′ = P− (ra · Pa + rb · Pb + rc · Pc + rd · Pd) / (ra + rb + rc + rd) Here, ra to rd are the probe 10p and the probes 8a to 8d.
And the distance. With this method, even if the position of the center of gravity G is unknown, it is possible to compensate for the effects of partial deformation and vibration of the support 7 of the cantilever 9 or the recording medium 6. Actually, the read error rate of the recording bit was reduced to about 1/10 of the conventional example.

FIG. 6 shows a configuration diagram of another embodiment. The basic configuration is the same as that of FIG.
The point that a and 8b are formed on the cantilever 9 is different from the point that the recording medium 6 has a recording layer 6b partially laminated on the Au thin film 6a. For the recording layer 6b, a single layer LB film of scalylium-bis-6-octylazulene is used, and the LB film is formed by the method disclosed in JP-A-63-161552. Here, the distance detection probes 8a and 8b are located on the Au thin film 6a, and the recording / reproducing probe 10 is located on the recording layer 6b.

First, the recording / reproducing probe 10 is connected to the plus side, and the Au thin film 6a is connected to the minus side, and the recording layer 6b is connected.
Was turned on by applying a rectangular pulse voltage of 10 V which is equal to or higher than the threshold voltage VthON shown in FIG. 7 which changes to a low resistance state (ON state). While maintaining the distance between the probe 10 and the recording layer 6b in the Z direction, the probe 10 and the Au thin film 6a
When a probe voltage Ip of 1.0 V was applied between them and the probe current Ip was measured, it was confirmed that a current of about 0.5 mA flowed and was turned on. next,
The probe voltage was set to 10 V which is equal to or higher than the threshold voltage VthOFF at which the recording layer 6b changes from the on-state to the off-state, and was applied to the recording position again. As a result, it was also confirmed that the recording state was erased and the off-state was changed.

In the above-described recording / reproducing experiment, similar results can be obtained by using the same compensation calculation method as described above.

[0028]

As described above, in the recording / reproducing apparatus according to the present invention, the effects of thermal drift and external vibration are reduced, stable operation is possible, and write / read errors of recorded information are reduced. In addition, higher density can be realized by more stable operation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a bottom view of a support portion.

FIG. 3 is a cross-sectional view of a bimorph cantilever.

FIG. 4 is a positional relationship diagram of each probe.

FIG. 5 is a positional relationship diagram of each probe.

FIG. 6 is a configuration diagram of another embodiment.

FIG. 7 is a voltage pulse waveform diagram.

FIG. 8 is an explanatory diagram of a conventional compensation mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibration isolation table 2 XY stage 3 Z direction coarse movement mechanism 4a, 4b parallel control mechanism 5 Recording medium holding part 6 Recording medium 7 Supporting parts 8a to 8d Distance detecting probe 9 Cantilever 10 Recording / reproducing probe 11 Coarse movement driving part 12 Parallel control unit 13 Tunnel current amplifier for detecting distance variation 14 Tunnel current amplifier for detecting recorded information 15 Z-direction feedback unit 16 Microcomputer 20 Si substrate

Continuation of the front page (72) Inventor Osamu Takamatsu 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Katsunori Hatano 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. (56) reference Patent flat 2-216749 (JP, a) JP flat 3-15704 (JP, a) JP flat 2-25702 (JP, a) (58 ) investigated the field (Int.Cl. ⁶ G11B 9/00 G01N 37/00

Claims (4)

(57) [Claims] An information probe disposed opposite to a recording medium.
The information recorded on the recording medium from the output of the
In the information reproducing apparatus, the same support as the information probe is used.
A plurality of distance detection probes supported by a table and arranged to face the recording medium, and an output of the information probe;
Calculating means for calculating data obtained by compensating for the distance variation with respect to the output of the information probe based on the outputs of the respective distance detecting probes and the positional relationship thereof;
Reproduction of information recorded on the recording medium with the data calculated in step
An information reproducing apparatus for outputting as a signal . 2. The information probe and each of the distance detectors
Means for applying a voltage between a probe and the recording medium
Between the probes and the recording medium.
Current detecting means for taking out a channel current as an output.
The information reproducing apparatus according to claim 1. 3. The output of said plurality of distance detection probes is
Positions of the support table and the recording medium so as to be equal.
2. The information according to claim 1, further comprising control means for controlling the relationship.
Playback device . 4. The method according to claim 1 , further comprising a plurality of said information probes ,
The means is based on the output of each information probe, the output of each distance detection probe, and the center of gravity of these probe devices.
Distance variation for each information probe based on the distance of
Calculate the data that compensated for the
The information reproducing apparatus according to claim 1, wherein the information reproducing apparatus outputs the information detected by the probe as a reproduced signal .