JP2000011471A - Probe having microopening, information recording and reproducing device having this probe and information recording and reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a probe having microopenings formed in such a manner that tracking may be executed without executing the intricate driving of the probe in an information reproduction means having a means capable of executing direct tracking to recording dot strings as well as an information recording and reproducing device having this probe and an information recording and reproducing method. SOLUTION: This probe is arranged opposite to a recording method surface for reading out the information recorded as recording dots on the recording medium and detects the proximity field light generated when the probe is brought near to the recording medium. The probe described above has the two microopenings at its tip part. The information recording and reproducing device or the information recording and reproducing method are constituted by the probe having the two microopenings.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe having a minute aperture to which a near-field microscope is applied, and an information recording / reproducing apparatus and an information recording / reproducing method provided with the probe. The present invention relates to a means for reproducing information using a probe capable of detecting a signal at two places, and a means for performing tracking control on a recording dot row using the probe.

[0002]

2. Description of the Related Art In recent years, a scanning tunneling microscope (hereinafter referred to as S) capable of observing the surface of a conductive material with a resolution of less than nanometers.
TM is abbreviated (U.S. Pat. No. 4,434,993), and observations of the atomic arrangement of metal / semiconductor surfaces, the orientation of organic molecules, and the like have been made on an atomic / molecular scale. Also, by developing STM technology, the surface of insulating materials
Force microscope (hereinafter referred to as AF)
M) (US Pat. No. 4,724,318). As a development of the STM, a scanning near-field light microscope (hereinafter abbreviated as SNOM) for examining the surface state of a sample using evanescent light leaking from a minute opening at the tip of a sharp probe [Durig et al. App
l. Phys. 59, 3318 (1986)]. Further, a photon STM (hereinafter referred to as a PST), which is a kind of SNOM for examining the sample surface by allowing light to enter from the back surface of the sample through a prism under the condition of total reflection and detecting evanescent light seeping onto the sample surface from the sample surface with an optical probe, is used.
M) [Reddick et al., Phys. Rev .. B
39,767 (1989)].

An ultra-high-density recording / reproducing apparatus for recording information in a local area has been devised by applying the principle of SNOM or PSTM. Also, a proposal has been made regarding a recording / reproducing apparatus [US Pat. No. 4,684,206], which performs writing and reading on a recording medium using evanescent light by applying the principle of NFOM. An example in which a recording mark having a diameter of 60 nm is recorded / reproduced on a platinum / cobalt multilayer film using a probe having a small opening of several tens of nm, which is formed by processing the tip of an optical fiber [App
l. Phys. Lett, 62, 142 (1992)]
Have been reported. In the recording / reproducing apparatus to which the above-mentioned SNOM or PSTM is applied, the recording information that can be detected by the probe depends on the shape of the minute aperture and the distance from the recording medium, and is not limited by the wavelength of light. The recorded information can be reproduced, and the recording density can be dramatically improved as compared with the conventional optical recording.

[0004]

However, the above SNO
In a recording / reproducing apparatus to which M or PSTM is applied, a probe whose opening diameter at the tip of the probe is usually 100 nm or less is used. As a problem when such a minute probe is used, as shown in FIG. 9, reproduction is performed using a probe having a minute opening for a minute recording dot, so that the position of the probe may be a temperature or vibration. And the scanning direction of the probe drifts and deviates from the direction of the dot row. STM
Alternatively, in a recording / reproducing apparatus to which the AFM is applied, a method of directly tracking a recording dot row with respect to the above-described problem is disclosed in JP-A-4-212737. In this method, a probe is vibrated at a constant frequency in a direction perpendicular to the scanning direction, and a signal modulated according to a shift between the scanning direction and the recording dot row direction is detected to perform tracking. It is conceivable that a similar solution is applied to a recording / reproducing apparatus to which SNOM is applied. However, in the above method, it is necessary to vibrate the driving element faster than the scanning frequency.However, the displacement speed of the driving element for scanning the probe is defined by the resonance frequency inherent to the element. There is a problem that it is difficult to respond.

Therefore, the present invention solves the above-mentioned problem, and in an information reproducing means provided with means capable of directly performing tracking on a recording dot row, tracking can be performed without driving a complicated probe. It is an object of the present invention to provide a probe having such a small aperture, an information recording / reproducing apparatus and an information recording / reproducing method provided with the probe.

[0006]

In order to achieve the above object, the present invention provides a probe having a minute opening, an information recording / reproducing apparatus and an information recording / reproducing method provided with the probe.
It is characterized by having the following configuration. That is, the probe having the minute aperture according to the present invention is disposed to face the recording medium surface for reading information recorded as recording dots on the recording medium, and emits near-field light generated when the probe is brought close to the recording medium. A probe to detect,
The probe is characterized in that it has two minute openings at the tip. Further, in the probe having a small opening according to the present invention, the two small openings of the probe are arranged at an angle in which a direction connecting the two small openings is neither parallel nor perpendicular to the scanning direction. And Further, in the probe having the minute openings according to the present invention, the two minute openings of the probe may be such that when the probe is brought into contact with the recording medium, the two minute openings simultaneously contact the recording medium, or When the minute opening contacts, the distance between the other minute opening and the recording medium is 100 nm.
It is characterized in that it is formed as follows. Further, the probe having a small opening according to the present invention is characterized in that the two small openings of the probe are arranged so that the two small openings simultaneously detect signals from one recording dot. In addition, a probe having a small opening according to the present invention includes a cantilever and a probe arranged on the cantilever, wherein the two small openings are formed at the tip of the probe. .

Further, an information recording / reproducing apparatus according to the present invention comprises a recording medium, a probe arranged opposite to the recording medium surface and close to the recording medium surface, and Scanning means for irradiating the recording medium near the probe with light; and means for detecting near-field light generated near the probe and the recording medium. An information recording / reproducing apparatus for reproducing information recorded on the recording medium from a change in light intensity of light is provided with any one of the above-described probes of the present invention. Further, the information recording / reproducing apparatus of the present invention compares the intensity of a recording signal detected by two minute openings of the probe with information recorded as a recording dot row on the recording medium by scanning of the probe. Is provided. Further, the information recording / reproducing apparatus of the present invention includes means for performing feedback control of a probe position in a direction perpendicular to a scanning direction based on an output of the comparing means, and performing tracking for a recording dot row. It is characterized by: Further, the information recording / reproducing apparatus of the present invention is characterized in that the signal intensity compared by the comparing means is a local maximum value or a local minimum value of the signal intensity detected by each of the two minute apertures on the time axis. . Further, in the information recording / reproducing apparatus of the present invention, the signal strength compared by the comparing means is the signal strength when each of the signals detected by the probe is separated into signals derived from two small apertures. It is characterized by having. Further, the information recording / reproducing apparatus according to the present invention may further comprise a control means for performing feedback control of a probe position in a direction perpendicular to a scanning direction so that a ratio of the signal intensities compared by the comparing means becomes a certain value. It is characterized by having. Further, an information recording / reproducing apparatus according to the present invention is characterized in that the probe comprises a plurality of probes, and at least one of the probes includes any one of the above-described probes of the present invention. Further, the information recording / reproducing apparatus of the present invention is such that, in the plurality of probes, a probe having any one of the two minute apertures according to the present invention is used as tracking means,
It is characterized in that a probe formed by one other small aperture is used as a signal reproducing means.

Further, in the information recording / reproducing method of the present invention, the probe arranged opposite to the surface of the recording medium is scanned close to the surface of the recording medium, and the recording medium near the probe is irradiated with light. In the information recording / reproducing method for detecting near field light generated near the surface of the recording medium with the probe and reading information recorded as a recording dot array on the recording medium, any one of the probes according to the present invention described above as the probe Tracking the recording dot row by comparing the intensity of the recording signal detected by the two minute apertures of the probe and performing feedback control of the probe position in the direction perpendicular to the scanning direction based on the result. It is characterized by doing. Further, the information recording / reproducing method of the present invention is characterized in that the signal strength to be compared is a maximum value or a minimum value of the signal strength detected at each minute aperture on a time axis. Further, in the information recording / reproducing method of the present invention, the signal strength to be compared is the strength of each signal when the signal detected by the probe is separated into signals derived from two minute apertures. And Further, the information recording / reproducing method of the present invention is characterized in that the probe position is feedback-controlled in a direction perpendicular to the scanning direction so that the ratio of the signal intensities to be compared becomes a certain value. Further, the information recording / reproducing method of the present invention is characterized in that the probe comprises a plurality of probes, and at least one of the probes includes any one of the above-described probes of the present invention.
Further, the information recording / reproducing method of the present invention is characterized in that, in the plurality of probes, the probe having any one of the two fine apertures of the present invention described above is used as a tracking means, and the probe formed by the other one fine aperture is used. It is characterized by being a signal reproducing means.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, in the present invention, signals can be detected at two locations by a probe having two minute openings, and therefore, a single scan can be performed in comparison with a probe having one minute opening. The area where signals can be detected is widened, and the reliability of signal detection is improved. Further, in the present invention, when the probe is brought into contact with the recording medium arranged opposite to the probe, the two minute openings simultaneously contact the recording medium, or when one of the minute openings comes into contact with the recording medium. And the distance between the other minute opening and the recording medium is 100n.
By setting m or less, it becomes possible to detect the evanescent light existing in the vicinity of about 100 nm or less of the recording medium.

These will be further described. As shown in FIG. 2, in the information recording / reproducing apparatus of the present invention, two small openings of the probe are arranged obliquely at an angle θ with respect to the scanning direction. At this time, the probe is arranged so that, in one scan, the two minute openings of the probe both detect signals from one recording dot, so that the center of gravity of the two minute openings is When passing above, it is possible to prevent a situation in which neither of the two minute openings can detect a signal from the recording dot, and it is possible to always detect a deviation of the probe from the recording dot row. When the minute aperture passes over the recording dot, the preceding minute aperture in the scanning direction detects the signal first, and the other minute aperture detects the signal with a time delay. The signal detected by the probe is the superposition of the signals detected by the respective small apertures, and has a signal waveform composed of two peaks on the time axis as shown in FIG. Therefore, signals detected by the two minute apertures can be identified on the time axis.

Here, a small aperture preceding the scanning direction is A, and the other small aperture is B. If the probe is shifted to the left with respect to the recording dot row, the intensity of the temporally preceding signal detected by the minute opening A decreases relatively to the intensity of the temporally late signal detected by the minute opening B. I do. On the other hand, if the probe is shifted to the right with respect to the recording dot row, the signal intensity of the slower time detected by the minute aperture B is relative to the earlier signal detected by the minute aperture A. To decrease. From the relative change of these two signal intensities, it is possible to detect the direction of deviation of the probe in the direction perpendicular to the scanning direction. Tracking can be performed by feeding back to the probe position control in a direction perpendicular to the scanning direction according to the displacement direction and the displacement amount of the probe. At this time, the deviation direction from the recording dot row of the probe can be detected by taking the respective peak intensities of the signal having two detected peaks as the signal intensity to be compared. Alternatively, by separating the detected signal waveform into signal waveforms detected by the two minute apertures and comparing the integrated intensity of each waveform or the waveform modified with respect to each waveform, the probe can be used. The direction of deviation from the recording dot row can be detected. At this time, by performing feedback control of the probe position in a direction perpendicular to the scanning direction so that the ratio of the signal intensities to be compared becomes a certain value, tracking can be performed on the recording dot row. .

[0012] As a configuration of the probe, a cantilever,
Consisting of a probe arranged on the cantilever, having two small openings at the tip of the probe, so that when the probe contacts the recording medium, the contact force is absorbed by the spring force of the cantilever. Can be. Further, by configuring a multi-probe type recording / reproducing apparatus having a plurality of probes having two minute openings, it becomes easy to increase the recording density and the transfer rate. Further, the probe having the two minute openings is used for tracking,
By using a probe having two small openings for signal reproduction, a probe having one small opening can accurately scan a recording dot row without performing a tracking operation.

[0013]

Embodiments of the present invention will be described below. [Embodiment 1] FIG. 5 shows a probe used for a reproducing apparatus in Embodiment 1. In the present embodiment, the probe is a probe 501 having a minute opening 502 at the tip, and a cantilever 5.
It was formed in a 03 shape. FIG. 1 shows the shape of the probe portion as viewed from directly above and from the side. As shown in FIG. 1, the probe has an approximately pyramid shape surrounded by four surfaces. However,
The four surfaces are slightly displaced without intersecting at one point and have saddle-shaped tips. Further, the saddle-shaped tip portion forms a tip at two locations, and a minute opening is formed at each of the two locations. As shown in FIG. 5, the probe was formed so that the line connecting the two minute openings was arranged obliquely to the scanning direction.

The above probe was prepared as follows. First, as shown in FIG. 7A, an SiO ₂ mask excluding a rectangular portion of 3 μm square is used as a protective layer 702 on a Si substrate 701 having a plane orientation (100), and photolithography and a KOH solution are used. By performing crystal anisotropic etching, a pyramid-shaped groove is formed. Next, FIG.
As shown in FIG. 7, a pyramid-shaped groove is thermally oxidized to form a thermal oxide film 703 on the surface. As a result, the tip is sharpened so that one surface of the pyramid-shaped groove is convex inward. Next, as shown in FIG. 7C, a Pt film 705 having a thickness of 0.1 μm is formed by a sputtering method, and then the probe tip coating portion and the electrode wiring are patterned. After that, low pressure C
After forming a 1 μm thick Si ₃ N ₄ film 704 by VD, patterning is performed in a cantilever shape. Further, as shown in FIG. 7D, a glass substrate 70 is used to support the cantilever.
6 is anodically bonded. Next, the Si substrate 701 is
Was removed, and the thermal oxide film 703 was removed with a mixed aqueous solution of hydrofluoric acid and ammonium fluoride. As described above, an elastic cantilever having a fine opening at the tip of the probe coated with Pt was formed.

The created probe has a base length of about 3 μm,
The height is about 4 μm and the distance between the two tips is about 0.1 μm
m. In the above-described sharpening process by thermal oxidation, the radius of curvature at the tip can be controlled by controlling the thermal oxidation time. As the thermal oxidation progresses and the radius of curvature is smaller, the area where the metal is not coated at the tip in the sputtering process becomes larger, and as a result, the fine opening becomes larger. Two tips can be formed stably and two small openings can be formed when the radius of curvature of the tip is in the range of about 10 to 30 nm, and the diameter of the small openings at this time is about 20 to 50 nm.
Was in the range. Depending on the manufacturing method, the thickness of the metal film should be 10
If it is smaller than 0 nm, it tends to be difficult to form a continuous film. Since this is not suitable for the probe of the present invention, the thickness of the metal film is preferably about 100 nm. Further, when Pt is sputter-coated from the top on the concave portion serving as a probe tip, a probe having no fine opening at the tip can be produced.

FIG. 6 shows the configuration of the recording / reproducing apparatus according to the first embodiment. The cantilever 601 and the probe 602 constituting the probe are held by a support 604. Probe 6
The support 604 was fixed to the main body so that 02 faces the recording medium 603. At this time, the long axis direction of the cantilever 601 was arranged to be perpendicular to the direction in which the recording dot rows were arranged. Therefore, the direction connecting the two minute openings at the tip of the probe 602 is different from the direction in which the recording dot rows are arranged.
Neither at right angles nor parallel, they will be arranged diagonally.
The substrate 605 on which the recording medium 603 is loaded has conductivity,
An electrode for applying a voltage to the recording medium 603 was used. The substrate 605 is provided on a conductive sample pedestal 606. The sample pedestal 606 is fixed to the XY actuator 607. From the Pt thin film that coats the probe 602,
It is connected to the voltage application circuit 612 via a wiring.
The substrate 605 is also connected to the voltage application circuit 612 via the sample pedestal 606 so that a voltage can be applied to the recording medium 603. Laser light emitting element 608
Is arranged on the back surface of the probe in close proximity to the probe, and is designed so that the laser beam passes through the cantilever 601 and irradiates the probe 602 portion from the back surface.
Light scattered in the vicinity of the probe of the near-field light that has permeated through the minute opening at the tip of the probe is received by the photodiode 609.

As a recording medium used in the recording / reproducing apparatus of the present embodiment, an example of a recording medium whose optical characteristics change by applying a voltage is described in Japanese Patent Application Laid-Open No. 4-90152. 10,12-pentacosadioic acid, which causes a structural change in the diacetylene derivative polymer due to Joule heat caused by a locally flowing current and shifts the peak wavelength of the light absorption band. Further, as an example of a recording medium whose optical characteristics are changed by application of a voltage under light irradiation, a cis type only when irradiated with light as described in JP-A-2-98849 is used.
An azo compound having a quinone group and a hydroquinone group that causes a trans-type photoisomerization reaction to form a redox pair and transfer protons between the redox pair when an electric field is applied.

Next, the operation at the time of recording will be described. The recording data is binarized and converted into a data string associated with a recording point specified by coordinates on the recording medium. Here, the recording points are set in a grid pattern with a fixed interval. At this time, the interval between the recording points in the recording point row direction was set to 50 nm in order to secure a sufficient separation between the recording dots.
When the probe 602 reaches the recording point, the voltage application circuit 61
2 was driven to apply a pulse voltage between the probe 602 and the substrate 605 to cause a current to flow through the recording medium 604, causing the recording medium 603 to locally change its optical characteristics. Next, the operation at the time of reproduction will be described. When the probe 602 is irradiated with laser light, evanescent light is generated near the minute opening. The wavelength of the laser light is adjusted to the absorption peak of the recording dot on the recording medium.
Therefore, in the recording dot portion, the light absorption rate is high, and the evanescent light is weak. Although not shown, the coarse movement mechanism is driven to move the probe closer to the surface of the recording medium. The probe 602 is approximately 10
When the distance approaches 0 nm or less, the evanescent light is scattered on the recording medium surface 603, and the scattered light is detected by the photodiode 609. The photocurrent signal detected by the photodiode 609 is converted into a voltage signal by an IV conversion circuit 610, and further converted into a voltage signal by a signal comparison circuit 61.
Sent to 1. In this embodiment, the probe is brought into contact with the recording medium. At this time, the contact was monitored by the detection intensity of the near-field light. In other words, the near field changes remarkably according to the distance between the minute opening and the recording medium. However, if the minute opening comes into contact with the recording medium, even if the cantilever is displaced in a direction in which the probe approaches the recording medium, the near-field light can be changed. Using the fact that the detection intensity does not change much, it was possible to detect the contact of the probe. In this embodiment, since the probe having the cantilever is used, even in a state where the probe is in contact with the recording medium, the load applied to the probe is suppressed by a certain overload because the cantilever absorbs the load. Therefore, the recording medium is not damaged. Therefore, the distance between the recording medium and the base supporting the cantilever is not strictly controlled. Next, the XY actuator 607
To cause the probe to scan over the recording medium. In the signal comparison unit, the displacement of the probe position with respect to the recording dot row is detected from the change in the signal detected by the photodiode 609, and information for correcting the probe position is obtained. When the minute aperture of the probe approaches the recording dot, it is observed that the evanescent light is most modulated in the recording dot portion. Actually, since the tip of the probe usually has a radius of curvature of about several tens of nm, the current distribution on the time axis is a distribution curve reflecting a small aperture diameter,
The minute aperture has a peak at the time t when it approaches the recording dot most.

By the way, the probe is arranged such that the two small apertures of the probe detect signals from one recording dot in one scan.
When the center of gravity of the two small apertures passes over the recording dots,
It is possible to prevent a situation in which neither of the two minute apertures can detect a signal from the recording dot, and it is possible to always detect a deviation of the probe from the recording dot row. For that purpose, it is necessary that the projection (sine) in the direction perpendicular to the scanning direction of the line segment connecting the two small openings does not exceed the distance in the horizontal direction where the small openings can detect the recording dots. . The distance over which the minute opening can detect a recording dot is limited by the minute opening diameter and the resolution of the minute opening determined by the distance between the recording medium and the minute opening. In the case where the minute opening is in contact with the recording medium as in this embodiment, the diameter is almost equal to the minute opening diameter. Further, in order to prevent the signals of adjacent recording dots from being detected by being overlapped, the projection (cosine) of a line segment connecting the two tips of the probe in a direction parallel to the scanning direction is taken. It is necessary not to exceed the interval.

Next, a control method for performing tracking will be described with reference to FIGS. In the figure, the signal detected by the minute aperture is expressed such that the part that is most modulated has an upwardly convex peak. Note that the actual signal depends on the properties of the recording dot whether the detection light on the recording dot is larger or smaller than the light detected in the surrounding area. Since the two small openings of the probe are arranged obliquely to the scanning direction, when the probe passes over the recording dot, the one of the two small openings that precedes the scanning direction in the scanning direction has a signal first. And the other detects the signal with a delay with respect to it. Therefore, the detection signal waveform, which is the superposition of these signals, has two peaks as shown in FIG. As described above, even if one detection system is used for two small apertures, signals detected by the respective small apertures can be identified on the time axis. It is assumed that the small opening A precedes the scanning direction, and the other small opening is B. As shown in FIG. 4 (b), if the probe is shifted to the right with respect to the recording dot row, as shown in FIG. The intensity decreases, and the signal detected earlier by the minute aperture A is increased.

Conversely, if the center of gravity of the two leading ends shifts to the left with respect to the direction in which the recording dot rows are arranged, the signal intensity detected earlier by the minute aperture A decreases, and the minute aperture A decreases. The intensity of the signal detected late in time for B to detect will increase. As described above, the direction and amount of displacement of the probe are estimated from the relative change in the two signal intensities.
Since the detected signal has a spread centered on the peak according to the distribution curve, when the two signals overlap, a peak appears at a position slightly shifted from the original peak position. In this embodiment, in order to compare the signals detected by the two tips, the signal intensities at the two peaks were compared. At this time,
The detection of the relative change in the peak intensity does not necessarily require an accurate intensity, and the displacement direction of the probe can be sufficiently predicted.

Further, in order to accurately compare the signals detected by the two tips, it is necessary to separate them into respective signals.
For example, the signal waveforms can be separated by approximating them with a Lorentz-type curve and performing curve fitting using the peak intensity and the half width as parameters. By comparing the relative change in the peak intensity or the integrated intensity of the separated signals, the direction of displacement of the probe can be predicted. Here, a description has been given of a recording dot array arranged on a straight line, but even when recording dots are arranged on a circle,
If the probe makes a circular motion relative to the recording medium around the center of the circle on which the recording dots are arranged, and if the arrangement of the fine apertures in the scanning direction is constant, the displacement direction of the probe according to the same principle Can be predicted.

Next, the tracking operation will be described. The signal comparing unit 611 recognizes the signal as a signal from a portion where a recording dot is formed when the photodiode 609 locally detects a signal that is more strongly modulated than the preceding and following portions on the scanning line. . At this time, a specified level was set, and only a signal exceeding the specified level for a certain time length was recognized as a recording dot, and a signal having a time length shorter than that was judged as noise. Next, the signal comparison unit 611
From the signals detected by the photodiode 609, peak intensities derived from each of the two minute apertures were detected, the intensities of the respective signals were compared, and the ratio of the respective peak intensities was obtained. From the ratio of the peak intensities, the shift amount and the shift direction of the probe position from the recording dot row were detected.

Next, the control unit predicts the positions of the preceding and succeeding recording points with reference to the recording dot positions. If no current is detected near the recording points, it is assumed that there is no recording dot.
Recognizing the signal as OFF, and in the case of ON, the control unit outputs the output of the signal comparison unit to the feedback control circuit, and the feedback circuit 614 controls the ratio of the peak intensities of the signals derived from the two tips to be constant. Then, the actuator drive circuit 613 is controlled. As described above, when the reproduction was performed on the recording dot row, tracking could be performed.

[Embodiment 2] Embodiment 2 of the present invention relates to a reproducing apparatus using a plurality of probes, in which one or a plurality of probes have two small apertures. Is a probe having one minute aperture. FIG. 8 is a probe arrangement diagram in the present embodiment. FIG. 9 is a schematic configuration diagram of the present embodiment, and a portion surrounded by a dotted line in the drawing corresponds to FIG. 8 and 9 show a probe 1 having two minute openings.
Although three probes including a probe are shown, the number of probes is not limited. In FIG. 8, the right end probe 803 has two minute openings at the tip. The other probes 801 and 802 are probes having only one minute aperture. Probe 803 with two small openings
Is used for signal detection and tracking.
On the other hand, the probes 801 and 802 having one minute opening
Is used only for signal detection.

Probe 803 having two minute openings
Was formed by the same process as that of the probe in Example 1. On the other hand, a probe 8 having only one minute aperture
Nos. 01 and 802 were formed by making the mask shape not a rectangle but a square in the process of forming the concave portion serving as a probe in the formation of the probe in Example 1. Therefore, a probe having one minute opening and a probe having two minute openings can be formed by the same process. The plurality of probes 801 to 803 are integrally formed with the probe support members 804 to 806. Also, a plurality of high-sensitivity photodiodes 8 such as avalanche photodiodes are provided on the surface.
Photodiode support member 80 for producing 08-810
7 are bonded to and integrated with the probe support members 804 to 806. At this time, the position of the photodiode is
Behind the micro aperture of the corresponding recording / reproducing probe (=
Upper part).

A support member 807 supporting a plurality of probes and photodiodes is fixed to an XY actuator 901. The detection signal of the photodiode is I-
The signals are output to the V conversion circuits 1 (904) to 3 (906) and are converted into voltage signals. Substrate 8 on which recording medium 812 is loaded
13 is a transparent substrate having conductivity such as ITO,
The electrodes serve as electrodes for transmitting a light and applying a voltage to the recording medium 812 at the same time. Further, the substrate is fixed to a transparent holder 902 made of quartz or the like. The transparent electrode 813 is connected to a bias voltage application unit 909, and can apply a bias voltage. Recording medium 8
As the material 12, a material whose optical characteristics change when a voltage or an electric field is applied and a current flows as described in the first embodiment is used.

Next, the recording operation will be described. The recording data is binarized and converted into a data string associated with a recording point specified by coordinates on the recording medium. Here, the recording points were set in a grid pattern with a fixed interval. At this time, the interval between the recording points in the recording point row direction was set to 50 nm in order to secure a sufficient separation between the recording dots. When the probe 803 reaches the recording point, the voltage application circuit 909 is driven to drive the probe 803 and the probe 801 or 8.
By applying a pulse voltage between any one of No. 02 and the substrate 813, a current was caused to flow through the recording medium 812, and the recording medium 812 was locally changed in optical characteristics. At a voltage application point by the probe 803, a recording dot for mainly performing tracking is formed, and at a voltage application point by another probe, a recording dot for information recording is mainly formed.

Next, the operation at the time of reproduction will be described. The laser light emitted from the laser diode 903 is
The recording medium 812 is constantly radiated through the transparent holder 902 and the transparent substrate 813. The incident angle of the laser is set so as to satisfy the condition of total reflection on the plane of the medium. At this time, the laser light does not pass through the recording medium,
Evanescent light is generated very near the recording medium surface of 0.1 μm or less. The wavelength of the laser light is adjusted to the absorption peak of the recording dot on the recording medium. Therefore, in the recording dot portion, the light absorption rate is high,
Evanescent light is weak. When the probe is at a distance of about 100 nm or less from the recording medium, the probe detects evanescent light. This evanescent light passes through a small opening at the tip of the probe and is detected by a photodetector behind it. The photocurrent signal detected by the photodetector is converted into a voltage signal by an IV conversion circuit.

The output signal of the IV conversion circuit 1 or 2 is sent to the signal processing circuit 907, where the signal is filtered,
Signal valid only for signals above threshold voltage 2
A value conversion process is performed. The signal processed by the signal processing circuit 907 is reproduced as information by a demodulation unit. On the other hand, the output of the IV conversion circuit 3 is sent to the comparison circuit 908,
A deviation from the recording dot row at the 03 position is detected. The method of detecting the deviation of the probe position from the recording dot row
According to the method described in the first embodiment. As described above, the recording dots are formed in a lattice pattern, and the interval between the probes is an integral multiple of the interval between adjacent recording dot rows. Therefore, if the position of one probe is determined,
The location of all other probes can be determined. Therefore, by controlling the position of the probe having two minute openings from the signal of the probe having two minute openings, it was possible to control the positions of all of the plurality of probes.

[0031]

As described above, according to the present invention,
Since a probe having two minute openings can detect a signal in two places, an area where a signal can be detected in one scan is wider than a probe having one minute opening,
The reliability of signal detection can be improved. Further, in the present invention, since tracking can be directly performed on recording dots, it is not necessary to provide a tracking track on a recording medium to be reproduced, and information to be reproduced is recorded on a recording medium at a high density. I can put it. Further, in the present invention, since a shift from a recording dot can be detected while performing a normal linear scan, a complicated operation of a probe for detecting a shift is unnecessary, and it is easy to cope with high-speed scanning. . Further, in the present invention, since the tracking can be directly performed on the recording dot row by one scan, the time required for detecting the recording dot can be shortened, and the reproduction can be speeded up. According to the present invention, by configuring a recording / reproducing apparatus using a plurality of probes including at least one probe having two minute openings, it is possible to track another probe using the probe having two minute openings. Becomes in this case,
Since the position control of the probe is only a correction in a direction perpendicular to the scanning direction, complicated movement of the probe is not required, and it is easy to respond to high-speed scanning.

[Brief description of the drawings]

FIG. 1 is a diagram showing the shape of a probe according to the present invention.

FIG. 2 is a diagram showing an arrangement of a minute aperture in a scanning direction in a probe of the present invention.

3A and 3B are diagrams illustrating a relationship between a signal waveform and the arrangement of a minute aperture and a recording dot passing position in the present invention.

FIGS. 4A and 4B are diagrams illustrating a relationship between a signal waveform and the arrangement of a minute aperture and a recording dot passing position according to the present invention.

FIG. 5 is a diagram showing a configuration of a probe according to the present invention.

FIG. 6 is a diagram showing a configuration of a first embodiment of the present invention.

FIG. 7 is a diagram showing a probe forming process in the present invention.

FIG. 8 is a diagram showing a configuration of a second embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a second embodiment of the present invention.

[Explanation of symbols]

501: Probe 502: Micro aperture 503: Cantilever 601: Cantilever 602: Probe 603: Recording medium 604: Support 605: Substrate 606: Sample base 607: XY actuator 608: Laser emitting element 609: Photodiode 610: I- V conversion circuit 611: signal comparison circuit 612: voltage application circuit 613: actuator drive circuit 614: feedback circuit 701: Si substrate 702: protective layer 703: thermal oxide film 704: Si ₃ N ₄ film 705: Pt film 706: glass substrate 801: Probe 1 802: Probe 2 803: Probe 3 804: Probe support member 805: Probe support member 806: Probe support member 807: Photodiode support member 808: Photodiode 1 809: Photodiode 2 810: Photodiode 3 901: XY actuator 902: Holder 903: Laser light emitting element

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA03 AA07 CC03 DD02 DD06 FF21 FF28 FF41 FF46 FF59 GG06 JJ18 MM03 PP12 PP22 PP26 QQ25 QQ28 UU06

Claims (19)

[Claims] 1. A method for reading information recorded as recording dots on a recording medium, the recording medium being arranged opposite to the surface of the recording medium,
What is claimed is: 1. A probe for detecting near-field light generated when approaching the recording medium, wherein the probe has two minute openings at a tip end. 2. The probe according to claim 1, wherein the two small apertures of the probe are arranged so that the direction connecting the two small apertures is not parallel or perpendicular to the scanning direction. Probe. 3. The probe according to claim 1, wherein the two small openings are contacted with the recording medium when the probe is brought into contact with the recording medium, or when one of the small openings is contacted with the recording medium when the probe is brought into contact with the recording medium. 3. The probe according to claim 1, wherein the distance between the other minute aperture and the recording medium is formed to be 100 nm or less. 4. The probe according to claim 1, wherein the two fine openings are arranged such that the two fine openings simultaneously detect signals from one recording dot.
The probe according to claim 3. 5. The probe according to claim 1, wherein the probe comprises a cantilever and a probe disposed on the cantilever, and wherein the two minute openings are formed at a tip of the probe. The probe according to any one of claims 4 to 4. 6. A recording medium, a probe opposed to the surface of the recording medium and arranged in proximity to the surface of the recording medium, and scanning means for causing the probe to scan the surface of the recording medium; Means for irradiating the recording medium in the vicinity of the probe with light, and means for detecting near-field light generated near the probe and the recording medium, wherein the recording is performed based on a change in the light intensity of the detected near-field light. An information recording / reproducing apparatus for reproducing information recorded on a medium, comprising the probe according to any one of claims 1 to 5. 7. A comparison means for outputting a result obtained by comparing the intensity of a recording signal detected by two minute openings of the probe with information recorded as a recording dot row on the recording medium by scanning of the probe. The information recording / reproducing apparatus according to claim 6, wherein the information recording / reproducing apparatus is provided. 8. A device according to claim 1, further comprising a means for performing feedback control of a probe position in a direction perpendicular to a scanning direction based on an output of said comparing means, and performing tracking for a recording dot row. Item 8. An information recording / reproducing apparatus according to Item 7. 9. The signal strength compared by the comparing means is:
8. The information recording / reproducing apparatus according to claim 7, wherein the signal intensity detected by each of the two minute apertures on the time axis is a local maximum value or a local minimum value. 10. The signal strength compared by the comparing means is the strength of each signal when the signal detected by the probe is separated into signals derived from two minute apertures. An information recording / reproducing apparatus according to claim 7. 11. A control means for performing feedback control of a probe position in a direction perpendicular to a scanning direction so that a ratio of the signal intensities compared by the comparing means becomes a certain value. The information recording / reproducing apparatus according to claim 7, wherein 12. The probe according to claim 1, wherein the probe comprises a plurality of probes, and at least one of the probes includes the probe according to any one of claims 1 to 5. An information recording / reproducing apparatus according to claim 11. 13. The method according to claim 1, wherein the plurality of probes are provided.
13. The information recording / reproducing apparatus according to claim 12, wherein the probe according to any one of claims 1 to 5 is used as tracking means, and the other probe formed by one minute aperture is used as signal reproducing means. apparatus. 14. A probe arranged opposite to the surface of the recording medium and scanned in the vicinity of the surface of the recording medium to irradiate light on the recording medium in the vicinity of the probe. An information recording / reproducing method for detecting generated near-field light and reading information recorded as a recording dot array on the recording medium, wherein the probe according to any one of claims 1 to 5 is used as the probe. Tracking the recording dot row by comparing the intensities of the recording signals detected by the two minute apertures of the probe, and performing feedback control of the probe position in a direction perpendicular to the scanning direction based on the comparison result. An information recording / reproducing method characterized in that: 15. The information recording / reproducing method according to claim 14, wherein the signal intensity to be compared is a maximum value or a minimum value of the signal intensity detected at each minute aperture on the time axis. 16. The apparatus according to claim 14, wherein the signal strength to be compared is the strength of each signal when the signal detected by the probe is separated into signals derived from two minute apertures. Information recording and reproduction method described. 17. The information recording according to claim 14, wherein the probe position is feedback-controlled in a direction perpendicular to a scanning direction so that a ratio of the signal intensities to be compared becomes a constant value. Playback method. 18. The probe according to claim 14, wherein the probe comprises a plurality of probes, and at least one of the probes includes the probe according to any one of claims 1 to 5. An information recording / reproducing method according to claim 17. 19. The method according to claim 1, wherein in the plurality of probes,
19. The information recording / reproducing apparatus according to claim 18, wherein the probe according to any one of claims 1 to 5 is used as tracking means, and the other probe formed by one minute aperture is used as signal reproducing means. Method.