JPH0636364A - Recording/reproducing device - Google Patents

Abstract

PURPOSE:To realize the recording/reproducing device which has a high read/ write speed and a high reliability by electrically, thermally, or optically changing the optical characteristic or the electrooptic characteristic of a minute area to record data on a recording medium. CONSTITUTION:A probe 2 is provided in the front end part of a cantilever 1 clipped by a supporting base body, and outer peripheral parts of the cantilever 1 and the probe 2 are covered with a metallic film 5. The cantilever 1 and the probe 2 are made of light-transmissive materials, and laser light is led into a laser leading-in part 7 from the side of the supporting base body 4 through a lens 8. In this case, data can be recorded in the area of <=0.1mum angle per pit, and the extrahigh-density recording/reproducing which is stably and surely operated is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus, including a scanning tunneling microscope (STM) and an atomic force microscope (AF).
The present invention relates to a recording / reproducing apparatus having an extremely large recording density, which skillfully applies the principles of M) and optical STM (PSTM).

[0002]

2. Description of the Related Art Magnetic disks and optical disks are widely used as large-capacity recording / reproducing apparatuses. Even in the optical disk capable of the highest density recording among these, the area per bit is limited by the wavelength of the light used and is about 1 μm square.

In the early 1980s, a scanning tunneling microscope (hereinafter referred to as S
Called TM) was developed. When a probe with a sharp tip is brought close to the sample surface to a distance of about 1 nm and an appropriate voltage is applied between the probe and the sample, a tunnel current flows. Since the magnitude of this tunnel current depends on the distance between the probe and the sample, if the probe is moved in the horizontal direction while moving the probe up and down so that the tunnel current is constant, the probe will move up and down. It is possible to know the nanometer-scale unevenness on the sample surface. It is also known that the sample surface can be processed from the atomic scale to several hundred nm scale by applying a pulse voltage larger than that at the time of surface observation to the probe.

As such an STM probe, a tip of a fine metal wire such as tungsten or platinum iridium is electrolytically or mechanically polished to have a radius of curvature of 0.1 μm or less.

Furthermore, in recent years, the STM is not only used as a means for observing surface irregularities by simply detecting a tunnel current or for fine processing, but also utilizing the interaction between a probe and a minute area on the sample surface. The application development to the means of has been made.

[0006] For example, an atomic force microscope (AFM) for measuring unevenness of the sample surface on the nm scale by detecting the magnitude of a minute atomic force generated between the tip of the probe and the sample surface as the deflection of the cantilever. ) Or irradiating a transparent sample with an external light source, and detecting photons tunneled by a pointed optical fiber probe,
Optical STM (P to measure changes in optical characteristics at m scale
STM) is being developed. A device derived from such an STM is called a scanning probe microscope.

Since the STM enables extremely fine observation and injection of electrons into a sample, application as a large-capacity recording / reproducing apparatus with a 1-bit recording area of 0.1 μm square or less is proposed by combining with the AFM. (J.Appl.Phy
s. 70 (5) 2725, 1 September 1991).

[0008]

[Problems to be Solved by the Invention] However, the STM
When applied as a large-capacity recording / reproducing device, there are problems in reading and writing speed, stability, life, and the like, and further reduction of the recording area per bit is desired for higher density and larger capacity. There is.

According to the present invention, recording is performed by electrically, thermally or optically changing the optical characteristics and electro-optical characteristics of a minute area of a recording medium, and a recording area of 1 bit is 0.1 μm.
It is an object of the present invention to provide a highly reliable large-capacity recording / reproducing apparatus with a high read / write speed of m square or less.

[0010]

DISCLOSURE OF THE INVENTION The present invention provides at least one of a detecting means for detecting light from a minute area of a recording medium, and an irradiating means for irradiating the minute area with light, and the recording medium. The conventional problem is overcome by a recording / reproducing apparatus including a writing / reading element including a probe provided with at least one of a potential measuring unit in a minute region or a voltage applying unit in a minute region of the recording medium. did.

[0011]

In the present invention, since the probe in which either the light irradiation means or the detection means is integrated with the potential measurement means or the voltage application means is used, the recording medium is electrically irradiated by the light irradiation. Material whose optical characteristics or optical characteristics change, electric characteristics which change electrical characteristics or optical characteristics due to heat (current) or electric field application, electric characteristics which apply electric field while irradiating light, or optical characteristics It is possible to select a wide range of materials, such as a material whose dynamic characteristics change, a high read / write speed, and a highly reliable large-capacity recording / reproducing apparatus.

[0012]

EXAMPLES Examples of the present invention will be specifically described below.

1 (a) and 1 (b) are block diagrams showing an embodiment of a write / read element of the present invention. The probe 2 is provided at the tip of the cantilever 1 sandwiched between the support bases 4, and the metal film 5 is provided on the outer periphery of the cantilever 1 and the probe 2.
Is covered with. Both the cantilever 1 and the probe 2 are made of a light transmissive material, and laser light is introduced from the side of the support base 4 through the lens 8 into the laser light introduction part 7.
The probe 2 may be bonded to the cantilever 1 with a transparent adhesive 3, for example, as shown in FIG.

The cantilever 1 is made of, for example, a photolithography process or the like and has a thickness of about 1 μm of SiO 2.
Transparent materials such as ₂ can be applied. Also, cantilever 1
The length is preferably a triangular shape having a length of about 200 μm.

A probe 2 is installed at the tip of the cantilever 1. As the probe 2, for example, a needle-shaped crystal of zinc oxide having a length of about 20 μm or the like can be applied. As a method of fixing the probe 2 to the cantilever 1, for example, a method of adhering and fixing using a transparent adhesive 3 such as an epoxy-based adhesive can be cited.

The base of the cantilever 1 is held by a metal supporting base 4. The entire surface of the cantilever 1 including the supporting substrate 4 can be covered with a gold thin film 5 having a thickness of about 100 nm by, for example, a sputtering method to form a transparent conductive film.

After that, the tip portion 6 of the probe 2 and the gold thin film 5 coated on the laser light introducing portion 7 at the base of the cantilever 1 are removed by, for example, mechanical polishing, and a writing / reading element is formed.

FIG. 2 shows a schematic diagram of the recording / reproducing apparatus of the present invention to which the write / read element 10 is attached. The structure is almost the same as that of the conventional optical disk, but especially the writing / reading element is different.

For the recording medium 9, for example, a ferroelectric polymer made of vinylidene fluoride / trifluoroethylene copolymer can be applied. The recording medium 9 is formed on a metal disk 11 rotated by a motor 12, and the probe 2 is brought into contact with the rotating recording medium 9 at a constant pressure by using the principle of an atomic lever microscope of an optical lever system. That is, the control laser light source 1
The cantilever is irradiated with the laser light from 3 and the reflected light is received by the photodetector 14 composed of a two-divided photodiode, and the probe 2 is moved up and down by using the two-dimensional fine movement device 15 so that the output becomes constant. Feedback control was performed by moving to. The two-dimensional fine movement device 15 can also be finely moved in the diameter direction of the disk for tracking control. Rough movement of the writing / reading element 10 in the diameter direction was performed by the slide mechanism 17 using a linear motor.

During recording, the metal disk 1 is set to the ground potential.
1, the light from the laser light source 16 is guided to the probe 2 through the cantilever 1 while applying a voltage of several to tens of V to the probe 2, and the tip 6 of the probe irradiates the recording medium 9. . The diameter of the irradiation area was about 100 nm. The laser-irradiated portion of the recording medium 9 was heated and polarized upward. When the polarity of the voltage applied to the probe 2 was negative, the polarization direction was reversed.

At the time of reproduction, a weak chopped laser beam is applied to the recording medium 9 from the tip 6 of the probe, and the electric charges induced on the surface of the ferroelectric polymer (recording medium 9) are transferred to the conductive zinc oxide. The tip 6 of the probe 2 detected the potential. The polarity of the potential changed depending on the polarization direction.

By the above method, a 1-bit signal could be recorded, reproduced and erased in a region having a diameter of 100 nm or less.

The recording / reproducing apparatus of the present invention is, for example,
Since random access can be made in about a second, it is optimal as a recording / playback device for long-term video information.

Further, by further sharpening the shape of the probe, the recording area can be further reduced, and a higher density recording / reproducing apparatus can be realized.

In the above embodiment, the voltage application function and light irradiation function of the probe were used for writing signals, and the potential measurement function and light irradiation function of the probe were used for reading. Various functions of the probe can be selectively used depending on the type of recording medium. For example, when a recording medium whose light transmittance changes due to heat is used, Joule heat due to an electric current flowing between the probe and the recording medium is used to write a signal, and the signal is read from the recording medium. It was also possible to irradiate the back surface or the surface with light from an external light source and use the light detection function of the probe.

That is, in the device of the present invention, the probe used in the writing / reading element functions as a fine electrode (electrode for measuring potential, applying voltage, flowing current).
Since it also has the function of irradiating and detecting light,
One of these functions when writing or reading
One or two or more can be used at the same time, a recording medium can be selected and used from many kinds of materials, and the reliability and stability of operation can be improved.

As the probe, a needle-shaped crystal of conductive zinc oxide (ZnO) was used in the above-mentioned embodiment, but a needle-shaped crystal of zinc selenide (ZnSe), silicon carbide (SiC) or the like is also used. I was able to. It is also possible to use a glass fiber whose tip is sharpened and whose surface is coated with a transparent conductive material such as indium oxide (In ₂ O ₃ ).

[0028]

As described above, according to the present invention, at least one of the detecting means for detecting the light from the minute area of the recording medium and the irradiation means for irradiating the minute area with the light, and the recording 1 bit because it is a recording / reproducing device including a writing / reading element including a probe provided with at least one of a potential measuring unit in a minute region of a medium and a voltage applying unit in a minute region of the recording medium. Per 0.1μ
Recording in an area of m square or less is possible, and an ultra-high density recording / reproducing device that operates stably and reliably can be realized.

Since this apparatus can be randomly accessed in about 1 second, it is optimal as a recording / reproducing apparatus for long-term video information.

By further sharpening the shape of the probe, the recording area can be further reduced, and a higher density recording / reproducing apparatus can be realized.

[Brief description of drawings]

FIG. 1A is a conceptual plan view showing the configuration of an embodiment of a write / read element applied to the recording / reproducing apparatus of the present invention. FIG. 1B is a write / read apparatus applied to the recording / reproducing apparatus of the present invention. Conceptual cross-sectional side view showing the configuration of one embodiment of the element

FIG. 2 is a schematic diagram of a recording / reproducing apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 1 Cantilever 2 Probe 3 Transparent Adhesive 4 Support Base 5 Gold Thin Film 6 Tip 7 Laser Light Introducing Section 8 Lens 9 Recording Medium 10 Writing / Reading Element 11 Metal Disk 12 Motor 13 Control Laser Light Source 14 Photodetector 15 2D Fine movement device 16 Laser light source 17 Slide mechanism

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kazuo Yokoyama 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] 1. A detection means for detecting light from a minute area of a recording medium, or an irradiation means for irradiating the minute area with light, and a potential measuring means for the minute area of the recording medium. Alternatively, a recording / reproducing apparatus including a writing / reading element including a probe provided with at least any one of voltage applying means for a minute area of the recording medium. 2. Writing to the recording medium is at least any one of current flowing between the probe and the recording medium, voltage application by the probe, and light irradiation from the probe. The recording / reproducing apparatus according to claim 1. 3. The reading from the recording medium is at least one of detecting a change in an optical characteristic of the recording medium and detecting a change in an electric characteristic of the recording medium. 1. The recording / reproducing apparatus according to 1. 4. The recording / reproducing apparatus according to claim 1, wherein the reading from the recording medium is performed by irradiating light from a probe and detecting a change in electrical characteristics of the recording medium. 5. The probe according to claim 1, wherein the probe is a light-transmitting substance, and at least a tip portion of the probe facing the recording medium is covered with a light-transmitting and conductive substance. The recording / reproducing apparatus described. 6. The recording / reproducing apparatus according to claim 1, wherein the probe is made of a light-transmitting and conductive needle crystal. 7. The recording / reproducing apparatus according to claim 6, wherein the acicular crystals are any one of zinc oxide, zinc selenide, and silicon carbide.