JP2001250275A - Surface-reproducing optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the vibration of a flying type SIL head without lowering the SNR in a surface reproduction type optical recording medium having a rewritable header area and a data area in which a guide groove is formed. To obtain stable levitation. SOLUTION: A guide groove is formed also in a header area, and the guide groove in the header area is formed shallower than the guide groove in the data area. In addition, the surface roughness (Ra) of the bottom of the guide groove in the header area and the recording surface of the header area of the substrate is set to 0.1.
The thickness is set to 5 nm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rewritable optical recording medium, and more particularly to a surface-reproducing optical recording medium for recording, reproducing and erasing information by irradiating a laser beam with a floating optical head.

[0002]

2. Description of the Related Art Optical recording media, such as magneto-optical recording media and phase-change recording media, are portable recording media capable of large-capacity, high-density recording. Demand for rewritable media for recording video and moving images is rapidly increasing.

In general, an optical recording medium is formed by forming a multilayer film including a recording layer on a transparent disc-shaped substrate such as plastic, irradiating a laser to record and erase, and reproducing by a reflected light of the laser.

[0004] Conventionally, magneto-optical recording media have mainly focused on so-called optical modulation recording in which a fixed magnetic field is applied to erase data and then recording is performed by applying a fixed magnetic field in the opposite direction. Has attracted attention as a method that can perform recording (direct overwrite) in one rotation and can accurately record even at a high recording density.

[0005] Phase change recording media have attracted attention because they can be directly overwritten by optical modulation recording and can be reproduced by the same optical system as CDs and DVDs.

Conventionally, a laser for recording / reproducing has been applied to a recording film through a substrate. Recently, so-called near-field optical recording, in which an optical head is brought close to a recording film to perform recording / reproducing, has attracted attention as a means for increasing the density (Appl.
hys. Lett. 68, p. 141 (1996)).
In this recording method, Solid ImmersionLe
By using an ns (hereinafter abbreviated as SIL) head to reduce the laser beam spot size, the conventional recording limit (限界 λ / 2) determined by the laser wavelength (λ) of the light source is obtained.
NA: NA can be recorded / reproduced with a mark shorter than the numerical aperture of the objective lens), and recording / reproducing with an extremely high recording density can be realized. In this near-field optical recording, it is necessary to bring the optical head close to the recording medium (20 to 200 nm). Therefore, instead of irradiating the recording film with a laser beam from the substrate side through the substrate as in a conventional optical recording medium, recording is performed. A method of directly irradiating the recording film with a laser beam from the film side is used. It has been proposed to use a floating SIL head for performing recording and reproduction by irradiating a laser beam while holding the SIL at a fixed distance from the surface of the optical recording medium.

The optical recording medium performs recording and reproduction for each sector while reading an address in a pre-pit portion called a header. The movement of the optical head to a place where the radius of the track is different is called a seek. In order to perform the seek at a high speed, a gray code that can detect the address of the header while seeking is sometimes used for the header.
Recording on the optical recording medium is performed on the recording film by the SIL head. The recorded mark is read at a certain distance from the lower surface of the SIL head, but the optimal focus is different in the pre-pit because the change in the reflectance due to the change in height from the lower surface of the SIL head is read. Also,
When seeks were repeated with a flying optical head, foreign matter could accumulate in the pre-pits, increasing errors in some cases. Therefore, in the surface-reproducing optical recording medium, it is conceivable that the header is formed by magneto-optical or phase-change recording marks.

[0008]

In order to improve the readability of the rewritable header of the surface-reproducing optical recording medium, a flat portion without a guide groove is formed as a header region on the substrate. Writing to a flat part is conceivable. However, when the flying type optical head is floated on such a medium surface, a phenomenon in which the head vibrates due to a slight foreign matter or fluctuation of mechanical characteristics has been observed. Also,
When the medium was a magneto-optical recording medium, a phenomenon was observed in which the recording marks in the header area were more unstable than the recording marks in the data area. An object of the present invention is to improve the instability associated with a rewritable header of such a surface-reproducing optical recording medium.

[0009]

Means for Solving the Problems The present inventors have made intensive studies in view of the above-mentioned current situation, and as a result, completed the present invention.

That is, the present invention relates to a surface-reproduction optical recording medium having a rewritable header area and a data area in which a guide groove is formed, wherein a guide groove shallower than the data area is formed in the header area. A surface-reproducing optical recording medium characterized by the following.

FIG. 1 is a schematic view of an embodiment of a surface-reproduction optical recording medium according to the present invention. Although FIG. 1 shows the number of sectors as 4 for simplicity, the actual number of sectors is about several tens to several hundreds. The guide groove is formed spirally or concentrically. The guide grooves are a guide groove 13 in the header area 11 and a guide groove 1 in the data area 12.
4 The shape of the guide groove is shown in the lower perspective view of FIG. 1. Regarding the groove depth, the guide groove 13 in the header area 11 is formed shallower than the guide groove 14 in the data area 12. Such a shallow guide groove, for example,
It is formed by lowering the laser power in the laser cutting step for producing a master disk (stamper) of the substrate as compared with the data part. In this case, although the groove width is reduced by lowering the power for forming the guide groove, the present invention is characterized in that the guide groove in the header area is formed shallower than the guide groove in the data area, The groove width does not necessarily have to be formed thin. These points are the same in FIGS.

FIG. 2 is a partial sectional view schematically showing a laminated structure of an embodiment of a surface-reproducing optical recording medium according to the present invention.
On a substrate 21, a reflective layer 22, a recording layer 23, a dielectric layer 2
4. A solid lubricating layer 25 and a lubricant layer 26 are laminated.

The substrate 21 is not particularly limited as long as it satisfies the characteristics of a medium substrate such as mechanical characteristics, and glass, polycarbonate, amorphous polyolefin, engineering plastic, or the like can be used. In the case of glass, it can be produced by an ultraviolet curing resin and a 2P method.

Although the structure of the thin film is not particularly limited in the present invention, the reflection layer 22 is made of Al, Al alloy, Ag, Au, Cu,
It is made of a metal having high reflectance and thermal conductivity such as an alloy containing at least one of them. The recording layer 23 is made of TbFeCo, N
A magneto-optical recording material such as dDyFeCo or a phase change recording material such as GeSbTe or AgInSbTe is used. Protective layers such as GeN may be inserted above and below for protection of the recording layer. If the dielectric layer 24 is optically transparent at the laser wavelength to be used, silicon nitride, germanium nitride, tantalum pentoxide, aluminum nitride, ZnS-S
Any of iO _{2 and the} like can be used. The solid lubricating layer 25 is made of a material such as diamond-like carbon or SiO ₂ that can ensure the floating property of the SIL head.
An optically transparent material is used at the laser wavelength used. The lubricant layer 26 is preferably made of a liquid material for ensuring lubricity, mainly a perfluoroether-based material.

An SIL is provided on the upper surface of the laminated structure having such a structure.
The head is raised and the header area 12
To write a header signal mark on the recording layer 23. In the case of magneto-optical recording, an optical pulse magnetic field modulation method of modulating a magnetic field while irradiating a laser pulse is used, and in the case of phase change recording, an optical modulation method is used.

It is considered that the SNR is high and a low error rate can be obtained when the header is written in a flat area having no guide groove. However, when the flying head is floated on such a medium surface, a slight foreign matter is generated. And a phenomenon in which the head vibrates due to fluctuations in mechanical characteristics.

It is considered that the cause of the disturbance of the flying property is fluctuation of the flying height of the head in a portion where there is no guide groove, and increase in stiction due to an increase in the contact area between the head and the disk. By forming a guide groove 13 shallower than the data area 12 in the header area 11, a high S
Variations in NR and flying height and suppression of stiction can be simultaneously achieved.

The depth of the guide groove in the data area is preferably 30 nm or more in order to obtain a good tracking state, and is preferably 100 nm or less from the viewpoint of the SNR of the recorded data. The depth of the guide groove in the header area is 5 nm or more and 30 n
By setting m or less, the error rate of the header region can be sufficiently reduced, which is preferable.

In the case where the medium is a magneto-optical recording medium, when the header area is a flat area without guide grooves, a phenomenon in which the recording mark is easily erased with a lower reproducing power than the data area is observed. By providing a guide groove in the header area, the stability of the recording marks in the header area and the data area becomes equal.

Furthermore, by using a substrate having a surface roughness (Ra) of 0.5 nm or less at the bottom of the guide groove 13 in the header area and the center of the land in the header area, it is possible to obtain a higher SNR. An error rate equivalent to the case where a flat area without a guide groove is used is obtained. Note that the center of the land in the header area is the center of the disk area (land) between the two guide grooves in the header area, and the surface roughness (Ra) is in the circumferential direction (along the guide groove). Direction). The surface roughness (Ra) of the bottom of the guide groove is also measured in the circumferential direction (the direction along the guide groove). For the measurement of the surface roughness, for example, an AFM (atomic force microscope) or the like can be used.

Incidentally, in order to accurately write header information in the header area, it is preferable that there is an area for generating a signal which triggers the writing of the header.

When the trigger signal is obtained by diffraction of laser light due to a change in the depth of the guide groove between the data area and the header area, the difference between the depth of the guide groove between the data area and the header area is preferably 20 nm or more. .

As schematically shown in FIG. 4, the boundary between the data area 42 and the header area 41 has a width of 20 in the circumferential direction.
Mirror part within μm (area where guide groove is not formed) 4
By providing 5, the signal intensity when the laser beam enters the header area 41 from the data area 42 increases. By setting the width of the mirror portion 45 within 20 μm, stiction becomes a negligible level.

In the substrate shown in FIG. 4, guide grooves are formed on the substrate in a spiral or concentric manner. The guide groove includes a guide groove 43 in the header area 41 and a guide groove 44 in the data area 42. The shape of the guide groove is shown in the lower perspective view of FIG. 4. Regarding the groove depth, the guide groove 43 in the header area 41 is better than the guide groove 4 in the data area 42.
It is formed shallower than 4. Such a shallow guide groove
For example, it is formed by lowering the laser power in the laser cutting process for manufacturing a master disk (stamper) of the substrate from the header portion compared to the data portion. in this case,
Although the groove width is reduced by lowering the power for forming the guide groove, the present invention is characterized in that the guide groove in the header area is formed shallower than the guide groove in the data area, and the groove width is It is not necessarily required to be formed thin.

Further, in order to increase the trigger signal strength, it is preferable that each header has one or more pits for setting the write timing as shown in FIG. In FIG. 5, each pit is separated between tracks. However, the detection of a trigger signal from such a separated pit can use diffraction of light incident on the pit, and the pit width causes diffraction. It is preferable that the diameter is sufficiently smaller than the diameter of the laser beam so as to make it easier.

As shown in FIG. 6, if the pits 65 for setting the write timing are connected in the radial direction from the inner circumference to the outer circumference, the amount of reflected light from the bottom of the pit and the amount of reflected light from the land can be improved. Alternatively, it is possible to obtain a trigger signal using a phase difference between reflected light from the bottom of the pit and reflected light from the land. In a system using SIL, the difference in reflectance or phase depends on multiple interference due to the distance between the plane irradiated with light and the bottom surface of the SIL head.
If the circumferential length of the pit is sufficiently larger than the beam diameter,
Since the pits are connected in the radial direction from the inner circumference to the outer circumference, diffraction does not occur, and a sufficient output can be obtained by a change in reflected light amount or a change in phase difference.

Also, as shown in FIG. 5 and FIG. 6, by providing mirror portions (regions in which guide grooves are not formed) each having a width of 10 μm or less before and after the pit, stiction can be reduced to a negligible level. Is preferred because the

When a gray code capable of detecting the address of the header while seeking is used to perform the seek at high speed, the header area is linearly arranged in the radial direction when the head moves linearly by the linear motor. In the case where the swing arm moves in an arc shape as shown in FIG. 7, it is preferably arranged in an arc shape in consideration of rotation, seek speed, and the like.

When the recording area is divided into a plurality of zones, it is preferable that the header areas are arranged linearly or arcuately in the radial direction for each zone.

Note that the fact that the header area is linearly arranged in the radial direction means that the header area is arranged on a straight line passing through the center of the disk as shown in FIG. 1, for example. The fact that the regions are arranged in an arc in the radial direction means that, for example, the portion 7 shown in FIG.
As shown by 2, the header area is arranged on a circular arc from the inner circumference to the outer circumference of the disk or a curve similar thereto.

[0031]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to only these Examples.

Example 1 A substrate having a header area and a data area as schematically shown in FIG. 6 and having a spiral guide groove was used, and the diameter of the laminated structure as shown in FIG. 2 was used. A surface reproducing type magneto-optical recording medium of 130 mm was manufactured. The substrate 22 made of polycarbonate provided with guide grooves having a track pitch of 0.4 μm (the guide grooves 63 in the header area 61 and the guide grooves 64 in the data area 62) is guided by the guide groove 63 in the header area at a depth of 20 nm and the data area. The groove 64 was formed by injection molding using a stamper having a depth of 75 nm. The depth of the guide groove on the stamper was controlled by changing the laser power at the time of ultraviolet laser cutting of an 80-nm-thick resist-coated master for manufacturing the stamper. In the header area, pits 65 connected in the radial direction, which trigger the writing of the header, were also formed at the same time. The header area was before the data area, the ratio of the lengths was 1:20, and 180 header areas / data areas were formed in one round. It was confirmed by AFM (atomic force microscope) that the guide groove had the same depth as the stamper even on the formed substrate 21. Similarly, the guide groove 63 in the header area is formed on the molded substrate 21 by the AFM measurement.
Surface roughness (R
a) was 0.7 nm and 0.6 nm, respectively.

On the manufactured substrate 21, 40
Au alloy reflective layer 22 nm, Curie temperature 2 at 20 nm
TbFeCo recording layer 23 at 00 ° C., 220 nm SiN
Dielectric layer 24, solid lubricating layer 2 made of 10 nm DLC
5 were stacked. Thereafter, a perfluoroether-based lubricant layer 26 was applied by a 1-nm pull-up method.

(Comparative Example 1) Header area 6 of stamper
A surface-reproducing type magneto-optical recording medium was manufactured in the same manner as in Example 1 except that the guide groove 63 was not formed in Example 1.

Comparative Example 2 A stamper was manufactured in the same manner as in Example 1 except that the laser power for cutting the header area was the same as that for the data area. The depth of the guide groove of the polycarbonate substrate 21 manufactured by injection molding using this stamper was 75 nm for both the header region and the data region. The surface roughness (R) of the bottom of the guide groove 13 in the header area and the center of the land in the header area
a) was 0.8 nm and 0.6 nm, respectively. afterwards,
As in Example 1, 22 to 26 layers were coated.

Example 2 After cutting the master, 16
A surface-reproducing magneto-optical recording medium was manufactured in the same manner as in Example 1, except that the resist was heat-treated at 0 ° C. The resist surface of the master was smoother than that of Example 1, and the surface roughness (Ra) of the bottom of the guide groove 63 in the header region and the center of the land in the header region on the molded substrate was 0.4 nm, respectively.
0.4 nm. Here, since 50 nm of resist remains at the bottom of the guide groove even after cutting in the header region, the surface roughness of both the bottom of the guide groove and the center of the land was improved in the header region by the resist heat treatment after cutting. The depth of the guide groove 13 in the header region and the depth of the guide groove 64 in the data region were slightly reduced to 15 nm and 70 nm on the substrate by the heat treatment of the resist. Thereafter, layers 22 to 26 were coated as in Example 1.

(Example 3) A polycarbonate substrate 21 produced by injection molding using the same stamper as in Example 1 was subjected to lamp annealing for 10 seconds on the substrate surface.
The substrate surface was smoothed by heating to 40 ° C. The guide groove becomes shallower by annealing, and the depth of the guide groove after annealing is 10 nm in the header region and 5 in the data region.
It was 0 nm. The surface roughness (Ra) of the bottom of the guide groove 63 in the header area and the center of the land in the header area were 0.3 nm and 0.3 nm, respectively. Thereafter, layers 22 to 26 were coated as in Example 1.

With respect to the surface reproducing type magneto-optical recording media of Examples 1 to 3 and Comparative Examples 1 and 2, the media were rotated at 2400 rpm, and a slider SIL head having a laser wavelength of 685 nm and an effective numerical aperture of 1.3 on the thin film surface. Is floated to a height of 50 nm, and the recording layer 23 is irradiated by irradiating a laser pulse.
Was heated above the Curie temperature, the coil magnetic field on the SIL head was modulated, and a header whose address portion was composed of a gray code was written in the header area. An AE sensor was attached near the SIL head, and the contact with foreign matter and the vibration of the head were examined.

As shown in Table 1, Examples 1 to 3 and Comparative Example 2
No significant signal from the AE sensor was observed from the inner circumference to the outer circumference of the disk (described as good in the table). It was shown that vibration was caused by stiction of the header portion.

In each of Examples 1 to 3 and Comparative Examples 1 and 2, the header could be written. For writing the header, a SUM signal from a pit 65 connected from the inner circumference to the outer circumference was used as a trigger. Table 1 shows the intensity of the trigger signal normalized by the level of the SUM signal on the land of the header portion. In each case, a sufficiently large and good signal was obtained.

SNR of playback signal of written header
Is 28 dB on average in Example 1 and 30 dB on average in Example 2.
B, averaged 32 dB in Example 3, averaged 29 dB in Comparative Example 1
However, in Comparative Example 2, the average was as small as 23 dB. In the first to third embodiments, the SNR of the reproduced signal of the header was within ± 1.5 dB depending on the location of the medium, but in Comparative Example 1, the variation was ± 4 dB, and particularly the vibration caused by the header portion occurred. The variation of the SNR at the place became remarkable.

Also, by comparing the first embodiment with the second and third embodiments, the surface roughness (Ra) of the bottom of the guide groove in the header area and the center of the land in the header area is reduced to 0.5 nm or less, thereby reducing the header area. The SNR was equal to or higher than the case where there was no guide groove.

With respect to Examples 1 to 3 and Comparative Example 1, a reproduction cycle test was performed at a reproduction power of 1.5 mW in the header area. In Examples 1 to 3, no reduction in SNR was observed in 10,000 regeneration cycle tests. In Comparative Example 1, the SNR was reduced by 2 dB after 10,000 regeneration cycle tests.

[0044]

[Table 1]

Example 4 A surface-reproducing optical phase-change recording medium having a diameter of 130 mm and a structure as shown in FIG. 3 was manufactured on the same substrate as in Example 2. A 40 nm Ag alloy reflective layer 32, a 20 nm ZnS—SiO ₂ layer 33, ₂₀ on a substrate 31.
GeSbTe recording layer 34, 180 nm ZnS-
After laminating an SiO ₂ dielectric layer 35 and a solid lubricating layer 36 made of 40 nm DLC, a perfluoroether-based lubricant layer 37 was applied to a thickness of 1 nm.

In Example 4, no remarkable signal from the AE sensor was observed from the inner circumference to the outer circumference of the disk. Also,
The SNR of the reproduced signal of the written header is 33d on average.
In B, the variation depending on the location of the medium was as good as ± 1.5 dB or less.

(Embodiment 5) A substrate having a header area and a data area as schematically shown in FIG. 1 and having a spiral guide groove is used, and the diameter of the laminated structure as shown in FIG. 2 is used. A surface reproducing type magneto-optical recording medium of 130 mm was manufactured. A polycarbonate substrate 22 having guide grooves with a track pitch of 0.4 μm (the guide grooves 13 in the header area 11 and the guide grooves 14 in the data area 12) was subjected to a resist heat treatment at 160 ° C. after cutting the master. Guide groove 13 having a depth of 15 nm and a guide groove 1 in the data area.
4 was produced by injection molding using a 65 nm deep stamper. The groove depth of the formed substrate was the same as that of the stamper. The depth of the guide groove on the stamper was controlled by changing the laser power at the time of ultraviolet laser cutting of a 70-nm-thick resist-coated master for manufacturing the stamper. The header area was before the data area, and the length ratio was 1:20, and 190 header areas / data areas were formed in one round. It was confirmed by AFM that the guide groove was almost the same depth as the stamper on the formed substrate 21. The SiN dielectric layer 24 is
A surface reproduction type magneto-optical recording medium was manufactured in the same manner as in Example 1 except that the thickness was set to 45 nm. The surface roughness (Ra) of the bottom of the guide groove 13 in the header region and the center of the land in the header region on the molded substrate were 0.4 nm and 0.4 nm, respectively.

(Embodiment 6) A substrate having a header area and a data area as schematically shown in FIG. 4 and having a spiral guide groove is used, and the diameter of the laminated structure as shown in FIG. 2 is used. A surface reproducing type magneto-optical recording medium of 130 mm was manufactured. A polycarbonate substrate 22 having a guide groove with a track pitch of 0.4 μm (a guide groove 43 in the header area 41 and a guide groove 44 in the data area 42) was subjected to a resist heat treatment at 160 ° C. after cutting the master. 15 nm deep in the guide groove 43, and the guide groove 4 in the data area.
4 was produced by injection molding using a 65 nm deep stamper. At the boundary between the data region and the header region, a mirror portion (region where the guide groove was not formed) having a width proportional to the radius (about 10 μm at the outermost periphery) was formed. The groove depth of the formed substrate was the same as that of the stamper. The depth of the guide groove on the stamper was controlled by changing the laser power at the time of ultraviolet laser cutting of a 70-nm-thick resist-coated master for manufacturing the stamper. The header area is before the data area, and the length ratio is 1: 2.
It was set to 0, and 190 header areas / data areas were formed in one round. It was confirmed by AFM that the guide groove was almost the same depth as the stamper on the formed substrate 21. A surface-reproducing magneto-optical recording medium was manufactured in the same manner as in Example 1 except that the SiN dielectric layer 24 was set to 245 nm. The surface roughness (Ra) of each of the bottom of the guide groove 43 in the header region and the center of the land in the header region on the molded substrate is equal to 0.1.
4 nm and 0.4 nm.

(Embodiment 7) A substrate having a header area and a data area as schematically shown in FIG. 5 and having a spiral guide groove is used, and the diameter of the laminated structure as shown in FIG. 2 is used. A surface reproducing type magneto-optical recording medium of 130 mm was manufactured. A polycarbonate substrate 22 having a guide groove having a track pitch of 0.4 μm (a guide groove 53 in the header region 51 and a guide groove 54 in the data region 52) was subjected to a resist heat treatment at 160 ° C. after cutting the master. 15 nm deep in the guide groove 53, and the guide groove 5 in the data area.
4 was produced by injection molding using a 65 nm deep stamper. In the header area, before and after the trigger pit having a half-value width of 150 nm and a length proportional to the radius (about 5 μm at the outermost circumference), a mirror portion (guide groove formed with a length proportional to the radius (about 6 μm at the outermost circumference) is formed. (A region that is not performed). The groove depth of the formed substrate was the same as that of the stamper. The depth of the guide groove on the stamper was controlled by changing the laser power during ultraviolet laser cutting of a 70-nm-thick resist-coated master for manufacturing the stamper. The header area is before the data area,
The length ratio was 1:20, and 190 header areas / data areas were formed in one round. Molded substrate 21
It was confirmed by AFM that the guide groove had almost the same depth as the stamper. The SiN dielectric layer 24 is 245
A surface reproduction type magneto-optical recording medium was manufactured in the same manner as in Example 1 except that the thickness was changed to nm. The surface roughness (Ra) of the bottom of the guide groove 53 in the header region and the center of the land in the header region on the molded substrate were 0.4 nm and 0.4 nm, respectively.

As shown in Table 1, in all of Examples 5 to 7, the signal quality of the header, the floating property, and the trigger signal were good.

[0051]

According to the present invention, by forming a guide groove shallower than the data area in the rewritable header area, the vibration of the flying type SIL head is suppressed, and a stable flying property is obtained. The guide groove in the header area is shallower than the data area, and the surface roughness (Ra) of the bottom of the guide groove in the header area and the center of the land in the header area is 0.5 n.
By using a substrate having a diameter of not more than m, a decrease in SNR due to the provision of the guide groove in the header region can also be suppressed. When the medium is a magneto-optical recording medium, by providing a guide groove in the header area, it is possible to obtain the same recording mark repetitive reproduction durability as the data area in the header area.

[Brief description of the drawings]

FIG. 1 is a diagram showing the structure of an example of a surface-reproduction optical recording medium according to the present invention.

FIG. 2 is a partial sectional view showing an example of a thin film structure when magneto-optical recording is used in the surface-reproducing optical recording medium of the present invention.

FIG. 3 is a partial cross-sectional view showing an example of a thin film structure when phase change recording is used in the surface-reproducing optical recording medium of the present invention.

FIG. 4 is a diagram showing the structure of another example of the surface-reproduction optical recording medium of the present invention.

FIG. 5 is a diagram showing the structure of another example of the surface-reproduction optical recording medium of the present invention.

FIG. 6 is a diagram showing the structure of another example of the surface-reproduction optical recording medium of the present invention.

FIG. 7 is a diagram showing the structure of another example of the surface-reproduction optical recording medium of the present invention.

[Explanation of symbols]

11, 41, 51, 61: header area 12, 42, 52, 62: data area 13, 43, 53, 63: guide groove in header area 14, 44, 64, 64: guide groove in data area 45: Mirror parts 55, 65: pits serving as triggers 21, 31, 71: substrate 22: reflective layer 23: recording layer 24: dielectric layer 25, 36: solid lubricating layer 26, 37: lubricant layer 32: Ag alloy reflective layer 33 : ZnS-Si0 ₂ layer 34: GeSbTe recording layer 35: ZnS-Si0 ₂ dielectric layer 72: the arc-arranged header area 73: slider 74: swing arm

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 11/105 521 G11B 11/105 521J 531 531X

Claims (11)

[Claims] 1. A surface-reproducing optical recording medium having a rewritable header area and a data area in which a guide groove is formed, wherein a guide groove shallower than the data area is formed in the header area. Surface-reproducing optical recording medium. 2. The surface-reproducing optical recording medium according to claim 1, wherein the depth of the guide groove in the header region is 5 nm or more and 30 nm or less. 3. The surface roughness (Ra) of the bottom of the guide groove in the header area and the center of the land in the header area is 0.5 nm.
3. The surface-reproducing optical recording medium according to claim 1, wherein the surface-reproducing optical recording medium is prepared using the following substrate. 4. The method according to claim 1, wherein the difference between the depths of the guide grooves in the data area and the header area is 20 nm or more.
4. The surface-reproducing optical recording medium according to any one of items 3 to 3. 5. The surface-reproducing optical recording according to claim 1, wherein a mirror portion having a circumferential width of 20 μm or less is provided at a boundary between the data area and the header area. Medium. 6. The surface-reproducing optical recording medium according to claim 1, wherein one or more pits for setting a write timing are formed in the header area. 7. A pit for setting a write timing is connected in a radial direction.
4. A surface-reproducing optical recording medium according to item 1. 8. The surface-reproducing optical recording medium according to claim 6, wherein a mirror portion having a circumferential width of 10 μm or less is provided before and after the pit for setting a writing timing. 9. The method according to claim 1, wherein the header areas are linearly arranged in the radial direction.
Item 2. The surface-reproducing optical recording medium according to item 1. 10. The surface-reproducing optical recording medium according to claim 1, wherein the header area is arranged in an arc in a radial direction. 11. A surface-reproducing optical recording medium in which a recording area is divided into a plurality of zones, wherein a header area comprises:
The surface-reproducing optical recording medium according to any one of claims 1 to 8, wherein the plurality of zones are arranged linearly or in an arc in a radial direction.