HK1077665A - Optical information-recording medium and method for producing the same - Google Patents

Description

Optical information recording medium and method for manufacturing the same

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Technical Field

The present invention relates to an optical information recording medium, and more particularly, to an optical information recording medium in which medium information such as a manufacturer name and copyright protection countermeasure information is written in the form of pre-pits.

Background

In recent years, DVDs (digital versatile discs) having a recording capacity several times that of CDs have been widely used as information recording media for recording information such as images and sounds of movies and the like. Further, as for the DVD, a DVD-R (digital versatile disc recordable) in which a user can record information only once or a DVD-RW (digital versatile disc rewritable) in which information can be rewritten is commercialized, and is widely used as an information recording medium having a large capacity.

In general, DVD-R and DVD-RW, information such as manufacturer information of an optical disc and information for copyright protection (hereinafter referred to as media information) is recorded in advance in the innermost circumference or the outermost circumference of the optical disc. These media information are recorded by a recording device in the final stage of the optical disc manufacturing process by changing the properties of the recording layer by light irradiation or the like. In contrast, a recording method has been disclosed in which media information is recorded in a groove (groove) of an optical disc in advance as a relief pit (hereinafter referred to as a pit-in-groove pit) in a substrate manufacturing stage of the substrate, instead of being recorded in the recording layer as described above (see, for example, patent document 1-japanese patent application laid-open No. 2001-67733, pages 5-6, and fig. 1-3). Fig. 1 shows a part of an optical information recording medium manufactured by this method. Fig. 1(a) is a partially enlarged plan view of an optical information recording medium, schematically showing a region where a pit in a groove is formed (hereinafter referred to as a pit-in-groove region). FIGS. 1(B) and (c) are a sectional view taken along line A-A and a sectional view taken along line B-B of FIG. 1(a), respectively. As shown in fig. 1 b, the optical information recording medium has a depth dp from a land surface 101a of a substrate 101 on which lands (lands) and grooves (grooves) are formed to a bottom surface (lowermost surface) 107a of a groove 107 deeper than a depth dg from the same land surface 101a to a bottom surface (lowermost surface) 105a of a groove 105. Thus, when the recording layer 102 and the reflective layer 103 are formed on the pattern forming surface of the substrate 101, the surface heights of the respective layers formed differ between the portions where the pits 107 in the grooves are formed and the portions where the pits 107 in the grooves are not formed. Therefore, by utilizing the difference in depth between the pit portion and the groove portion in the groove, data such as media information can be recorded on the groove.

However, when information is actually recorded and reproduced using an optical information recording medium having such a pit-in-groove, an error of tracking interruption is often found when tracking a boundary portion between a pit region in a groove and a region (hereinafter referred to as a groove region) in which only a groove as a user's recording region is formed. This is because, as shown in fig. 11, the side walls of the adjacent lands 152 are chipped off by forming in-groove pits 151 in the substrate. The upper surface of lands 152 between the grooves 151 and grooves 153 is smaller in area than the upper surface of lands 154 between the conventional grooves 153 because the side walls of adjacent lands 152 are chamfered. Accordingly, the areas of the recording layer and the reflective layer formed on the lands 152 and the lands 154 are also different. When the spot SP is used to trace the groove 153 between the land 152 and the land 154, even if the spot SP is located at the center of the groove 153, a difference occurs between the amount of reflected light RF1 obtained from the land 154 and the amount of reflected light RF2 obtained from the land 152, and an offset (offset) occurs in the radial push-pull signal. Thus, it is difficult to track the groove well, resulting in an increase in jitter and a decrease in modulation degree. In addition, tracking may be interrupted depending on the situation.

When an optical pickup (pick up) having a wavelength λ of 650nm and a numerical aperture NA of 0.6 is used for actually detecting a radial push-pull signal, a light spot having a diameter Φ of about 1 μm scans an optical information recording medium in a radial direction. At this time, since the optical recording information medium is rotated at a high speed, the light spot is not scanned in a direction perpendicular to the tracking direction but in a direction at a gentle angle to the tracking direction. Since the radial push-pull signal has no frequency characteristic that enables the pits to be detected with resolution, the pit portion in the groove formed deeper than the groove is equivalent to a groove having a large detection width. Therefore, in this case, the width of the groove extremely changes with the boundary between the pit region and the groove region in the groove as a boundary, and the radial push-pull signal is disturbed.

In particular, in DVD-R or DVD-RW, tracking is performed using the radial push-pull signal, and a tracking error is caused by an offset or a disturbance of the radial push-pull signal. Therefore, in DVD-R or DVD-RW, it is necessary to prevent the tracking error.

Disclosure of Invention

In view of the above, the 1 st object of the present invention is to provide an optical information recording medium and a method of manufacturing the same, which can obtain a stable radial push-pull signal even when a boundary portion between a pit region and a groove region in the groove is traced.

In addition, in the DVD-R with a high recording speed, errors after recording can be suppressed by a method of displaying position information (shifted-land pre-pit, referred to as SLPP) by projecting and curving a groove portion in a certain direction compared to the conventional land pre-pit method. In the pit-in-groove system, deeper pits are formed in the groove in order to record information in advance. When the information on the position information of the optical disc is formed in the SLPP method by wobbling (wobbble), the pits in the groove are inclined as shown in fig. 12. Such a shape has a problem that the DVD-R standard cannot be satisfied.

In view of the above, it is a 2 nd object of the present invention to stably provide an information recording medium and a method of manufacturing the same, which can simultaneously suppress errors of a pit-in-groove portion and a user portion where a user records data in a DVD-R in which a pit-in-groove is formed.

As a method for achieving the 1 st object of the present invention, there is provided: a 1 st groove; a 2 nd groove formed with a pit; the 3 rd groove having a groove wider than the 1 st groove is formed, and the 3 rd groove is disposed between the 1 st groove and the 2 nd groove, whereby tracking error and offset at the boundary portion can be suppressed.

As a method for achieving the object 2 of the present invention, the original LPP is used for the pit portion in the groove, and the SLPP is used for the portion where data is recorded, thereby satisfying various characteristics of both.

Drawings

FIG. 1(a) is a schematic plan view showing a part of an original optical information recording medium having pits in grooves; FIG. 1(b) is a sectional view taken along line A-A of FIG. 1 (a); FIG. 1(c) is a sectional view taken along the line B-B in FIG. 1 (a). FIG. 2 is a diagram illustrating a method of manufacturing a glass master according to an embodiment.

FIG. 3 is a graph showing the change with time of the exposure intensity of the glass master in the laser irradiation example.

FIG. 4(a) is a schematic plan view showing a part of a glass master after exposure and development of a photoresist in the examples; fig. 4(b) is a sectional view taken along line a '-a' of fig. 4 (a).

Fig. 5 is a schematic view of an area where a pit in a groove of the embodiment is not formed.

FIG. 6 is a diagram illustrating a method of manufacturing a glass master for a pit-in-groove forming region according to an embodiment.

Fig. 7 is a diagram illustrating a method of manufacturing a glass master without forming a pit area in a groove according to the embodiment.

Fig. 8 is a schematic perspective view of the pattern formation surface of the substrate obtained in the example.

FIG. 9 is a schematic view of a substrate obtained in example.

FIG. 10(a) is a schematic plan view showing the vicinity of a pit in a groove of a substrate according to an example; fig. 10(b) is a cross-sectional view taken along line C-C of fig. 10(a), and is a schematic cross-sectional view of a state in which a recording layer and a reflective layer are formed on a substrate.

Fig. 11 is a diagram illustrating the cause of the tracking error occurring at the boundary between the groove forming region and the in-groove pit forming region.

Fig. 12 is a schematic view of the case where a pit is formed in a groove in the SLPP method.

FIG. 13 is a graph showing the change with time of the exposure intensity of the glass master in the laser irradiation example.

FIG. 14 is a schematic view showing the 1 st groove region of the present invention.

Fig. 15 is a diagram showing a sum signal and a difference signal (radial push-pull signal) in the vicinity of a boundary portion between a pit region and a groove region in a groove, and shows these signals of an information recording medium produced in an example.

FIG. 16 is a layout diagram showing physical sectors of an optical information recording medium according to the present invention.

FIG. 17 is a drawing showing the introduction structure of the present invention.

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

Example 1

First, a method of manufacturing a master and a stamper for manufacturing a substrate will be described.

As shown in fig. 9, the substrate 1 of the optical information recording medium of the present invention is divided into, in order from the inner circumference of the substrate 1 to the outside: a groove region 71, a boundary groove region XX, a pit-in-groove region 73, a boundary groove region XX, and a groove region 75.

A method for manufacturing a master and a stamper for manufacturing the substrate 1 will be described with reference to fig. 2 to 9. As shown in FIG. 2(a), a glass master 50 having a diameter of 200mm and a thickness of 6mm was prepared. Next, as shown in fig. 2(b), a photoresist (photo resist)52 having a thickness of 220nm was uniformly applied on one surface 50a of the glass master 50 by a spin coat (spin coat) method. Next, the glass master 50 on which the photoresist 52 is formed is mounted on a dicing apparatus not shown. The cutting device (original disc exposure device) is mainly composed of an optical modulator, an optical deflector, a condenser lens, a driving device for rotating the glass original disc, and the like; the optical modulator is composed of a Kr gas laser source for generating laser light having a wavelength of 351nm and an acousto-optic modulator. As shown in fig. 2(c), the laser LS emitted from the laser light source of the cutting device is split into 2 beams by a beam splitter (beam splitter), and the beam 1 passes through the optical modulator, and the beam 2 passes through the optical modulator and the optical deflector. The beams 1, 2 are then combined by a prism beam splitter (prism beam splitter) and irradiated onto the photoresist 52 on the glass master 50 through a condenser lens. At this time, the glass original 50 is rotated around the central axis a of the glass original 50 at a constant number of revolutions. Further, the irradiation position of the laser LS on the glass original 50 is moved from the inside to the outside of the glass original 50 in the radial direction of the glass original 50 by moving the laser LS (arrow AR2) so that the beam 1 exposes the LPP of the in-groove pit portion and the beam 2 exposes the groove, the in-groove pit, and the SLPP.

The exposure is performed by exposing the beam 1 and the beam 2 at the same time, but the exposure is separately described here to avoid confusion.

First, the exposure of the LPP by the beam 1 is explained.

As described above, the exposure intensity of the laser beam LS irradiated onto the glass master 50 is changed by the optical modulator through which the light beam 1 passes while the laser beam LS is moved. The LPP is used for a signal inputted to the optical modulator when only the in-groove pit portion is exposed, and the radius of the in-groove pit portion is only 24.0mm to 24.1mm as shown in the beam 1 exposure pattern (LPP) of fig. 13.

Next, the exposure of the grooves, the pits in the grooves, and the SLPP by the light beam 2 will be described. Darkness

As described above, while the laser beam LS is moved, the exposure intensity of the laser beam LS irradiated onto the glass master 50 is changed by the optical modulator through which the light beam 2 passes, and the vibration is changed by the optical deflector. The region of 22mm to 24mm from the radius of the central axis AX of the glass master 50 corresponds to the groove region 71 of the substrate 1 shown in fig. 9 (hereinafter referred to as the 1 st groove forming region). The region having a radius of 24.0mm to 24.1mm corresponds to the in-groove pit region 73 (hereinafter referred to as an in-groove pit forming region) of the substrate 1. The radius of 24.1mm to 59.1mm is a user data area and corresponds to a groove area 75 of the substrate 1 (hereinafter referred to as a 2 nd groove forming area). In the groove, boundary groove regions corresponding to 1 track length are provided at the boundaries of the pit region and the groove regions 71 and 75, respectively.

In this embodiment, the exposure intensity of the 1 st and 2 nd groove forming regions is set at a groove level (level).

In addition, as shown in fig. 3, the exposure intensity of the laser light is changed in 3 steps in the in-groove pit forming region. The exposure intensity at the time of forming a portion corresponding to the in-groove pit of the in-groove pit forming region (hereinafter referred to as an in-groove pit forming portion) is set to two levels of the 1 st pit level and the 2 nd pit level, and the exposure intensity at the other groove portions is set to the groove level. In the present example, when the signal output at the 1 st pit level is set to 100%, the signal output at the 2 nd pit level is set to 63%, and the signal output at the groove level is set to 50% in the inner ring and 55% in the outer ring, the exposure intensity is continuously increased. The boundary groove area of the boundary between the groove area and the pit area in the groove is set to 1 track size. The exposure level at this time was 55%. SLPP was formed in all regions of the radius of 22mm to 24.0mm and 24.1mm to 59.1mm in FIG. 9. The SLPP is formed by changing the exposure intensity and the vibration amount of the beam 2 for exposing the groove. In the portion where the SLPP is formed, the exposure intensity is set to an intensity of + 4% of the groove level at the radius thereof (hereinafter referred to as an SLPPp level) so that the exposure intensity can be seen in the SLPP exposed portion of the beam 2 exposure pattern of fig. 13. In turn, beam 2 was vibrated at a frequency of about 140kHz with a photo-polarizer to produce a beam 2 polarization pattern as in FIG. 13. The vibration level signal was input with a vibration of about 140kHz to achieve an amplitude of 15 nmp-p. A signal of SLPPw level is applied to the optical polarizer in forming the SLPP to increase the amount of vibration of the portion. In this example, the SLPPw level was adjusted so that the amplitude of the SLPP portion was 150 nm. Also, SLPP is provided in the boundary trench region.

Further, as shown in FIG. 3, the exposure of the pit-in-groove forming portion is performed from 1T to 1.5T (T is a clock (clock cycle)) at the 1 st pit level, and then the exposure intensity is decreased to the 2 nd pit level, and further, the exposure intensity is again returned to the 1 st pit level between 1T and 1.5T until the end of the pit-in-groove forming portion, and thus, the width of the pit-in-groove forming portion in the radial direction of the original disk is not widened in the vicinity of the middle of the pit-in-groove forming portion, which is considered to be due to the decrease in the cumulative exposure amount during the exposure at the 2 nd pit level, and the extent of the exposure range in the radial direction of the original disk is suppressed, and further, the pit-in-groove pit region in the substrate forms a desired pattern at an arbitrary channel bit length of 3T to 11T or 14T in the track (groove) direction, and the pit-in-groove forming portion formed at the shortest channel length of 3T Since the width is widened again, the exposure intensity is not changed at the 2 nd stage as described above, but the exposure is performed at the 1 st pit level. In the present embodiment, by performing the above-described switching of the exposure intensity, the width of the in-groove pit-forming portion having the longer channel bit length than the shortest channel bit length can be made equal in size to the width of the in-groove pit-forming portion having the shortest channel bit length. Further, the clock period T can be adjusted as appropriate according to the reproducing apparatus used.

In the present embodiment, as shown in fig. 3, a period in which the exposure intensity of the laser beam is temporarily set to 0 level is provided every time the exposure intensity is switched from the 1 st pit level to the groove level or from the groove level to the 1 st pit level. The period of the level 0 varies depending on the channel length of the formed pit. When the pit-forming portion in the groove having the shortest channel bit length of 3T was exposed, the 0-level period was set to 0.2T. Thus, the processing accuracy of the pit forming portion in the groove of the master is improved.

Next, the glass master after the photoresist was exposed to light was taken out from the cutting device and subjected to a development process. The description will also be made with the pit portion and the groove portion in the groove separated.

First, the development process of the pit portion in the groove after exposure is described.

As shown in fig. 4(a) and 4(b), the groove forming portion 40, the in-groove pit forming portion 44, and the land pre-pit forming portion 42 of the in-groove pit forming region are formed on the glass master 50 by development. The groove forming portion 40 and the land pre-pit forming portion 42 are formed in a groove shape having a V-shaped cross section. At this time, the groove depth of land pre-pit forming portion 42 is deeper than the groove depth of groove forming portion 40. In addition, the photoresist 52 on the glass original 50 is removed by a developing process in the in-groove pit forming portion 44, and as shown in fig. 4, the surface 50a of the glass original 50 appears as an exposed portion 44 a.

Next, the development treatment of the groove and the boundary groove after the exposure is described.

By the development, the groove forming portion 40 and the SLPP forming portion 43 as shown in fig. 5(a) and (b) are formed in the glass master 51 in the 1 st and 2 nd groove forming regions in the same manner. The groove forming portion 40 and the SLPP forming portion 43 are formed in a groove shape having a V-shaped cross section. In this case, the SLPP forming portion forms a deeper V-shaped groove because of the higher exposure intensity than the groove portion. The boundary grooves are exposed to light with a greater intensity than the grooves having a similar radius, and therefore are deeper than the grooves. Further, since the groove portion is set so that the exposure intensity increases from the inner ring to the outer ring, the depth becomes deeper continuously from the inner ring to the outer ring.

The glass master was subjected to etching treatment by a reactive ion etching treatment apparatus not shown. The etching of the pit portion and the groove portion in the groove is performed simultaneously, and for convenience of description, the description will be divided.

First, reactive ion-etching (RIE) processing of the pit portion in the groove will be described.

As shown in FIG. 6(a), the RIE apparatus (not shown) is used at C₂F₆The surface of the photoresist 52 formed on the glass master 50 is etched in a gas atmosphere. Thus, the in-groove pit-forming portions 44 are etched from the surface 50a of the glass master 50 to a depth of 90nm, respectively. At this time, the etching amount of glass and photoresist was about 2: 1. Subsequently, as shown in FIG. 6(b), in order to expose the groove forming part 40 and the surface 50a of the glass master 50 of the land pre-pit forming part 42, O is used as a non-illustrated material₂The resist ashing (resist ashing) apparatus of (a) removes the photoresist 52 to a certain thickness. Thus, the groove forming part 40 and the groove are formedThe glass original surface 50a of the land pre-pit forming portion 42 is exposed. Further, as shown in FIG. 6(C), at C₂F₆+CHF₃The photoresist 52 forming face of the glass master 50 is subjected to reverse RIE in a gaseous atmosphere. Thus, the groove forming portion 40 is etched from the glass master surface 50a to a depth of 170 nm. The amount of glass and photoresist etched at this time was about 3: 1. In addition, since land pre-pit forming portion 42 has the same bottom as the groove forming portion, the groove bottom and the land pre-pit bottom have the same depth. At the same time, the in-groove pit-forming portions 44 were etched from the glass original disc surface 50a to a depth of 260 nm. Next, as shown in fig. 6(d), the photoresist 52 on the glass master 50 is removed again using the resist ashing apparatus. Thus, a glass master 50 having a desired pattern formed on the surface thereof is obtained.

Next, the reactive ion etching process of the groove portion and the boundary groove portion will be described.

The RIE process for the groove and the boundary groove will be described with reference to fig. 7. The same processing as in FIG. 6 is performed, and as in FIG. 7(a), the RIE apparatus (not shown) is used at C₂F₆Etching is performed in a gaseous atmosphere. In this case, the grooves, the boundary grooves, and the SLPP portions are not etched because the glass surface is not exposed. Next, as shown in FIG. 7(b), use O (not shown) is used₂The resist ashing apparatus of (1) removes the photoresist 52 only to a certain thickness. Thus, the groove, the boundary groove, and the glass original surface 51a of the SLPP portion are exposed. Then, as shown in FIG. 7(C), at C₂F₆+CHF₃RIE was performed on the photoresist 52 formation surface of the glass master 51 in a gas atmosphere. Thus, the groove forming portion 40 is etched from the glass original surface 51a to a depth of 170nm in the inner periphery and 180nm in the outer periphery. The depth of the groove forming portion becomes continuously deeper from the inner ring to the outer ring. Subsequently, as shown in fig. 7 d, the photoresist 52 on the glass master 51 is removed again using a reactive ion etching apparatus (not shown). Thus, a glass master 51 having a desired pattern formed on the surface thereof was obtained.

An electroless plating process is performed as a pre-plating process on the pattern-formed surface of the glass master 50. Then, by using this plating layer as a conductive film, a Ni layer having a thickness of 0.3mm was formed by electroforming. Next, the surface of the Ni layer formed on the glass master 50 was polished, and then the Ni layer was peeled off from the glass master, thereby obtaining a stamper. The conductive film subjected to the plating pretreatment may be formed by sputtering or vapor deposition.

Next, a method of manufacturing the information recording medium will be described.

The stamper is mounted on an existing injection molding apparatus, and the substrate 1 is obtained by injection molding. The substrate 1 was a polycarbonate substrate having a diameter of 120mm and a thickness of 0.6mm, and as shown in FIG. 8, a pattern having the same shape as the concave-convex pattern formed on the glass master was transferred to one surface of the substrate 1. As described above, the groove region 71, the groove pit region 73, the groove region (user data region) 75, and the boundary groove region are formed on the substrate 1. As shown in fig. 10(a), groove 80, land pre-pit 82, and in-groove pit 84 are formed in-groove pit region 73. In this case, the width of the substrate radial direction of the pit in the groove having the shortest channel bit length of 3T and the width of the substrate radial direction of the pit in the groove having a longer channel bit length than that were measured by a scanning probe microscope manufactured by digital instrument corporation. The maximum width of the pits in the groove having the shortest channel bit length of 3T is 0.34 μm. In addition, the maximum width of the pits in the groove having the channel bit length 11T is 0.38 μm. And, the maximum width of the pit in the groove having the channel bit length 14T is 0.4 μm. It is found from experiments by the present inventors that the ratio of the maximum width of the pits in the groove having the channel bit length longer than the shortest channel bit length 3T to the maximum width of the pits in the groove having the shortest channel bit length 3T is in the range of 112 to 118%, and the width in the substrate radial direction is suppressed in the pits in the groove longer than the shortest channel bit length.

On the pattern forming surface of the substrate 1, a solution having a concentration of 1 wt% of a dye for ordinary azo eight-speed recording was applied by a spin coating method to a land portion between grooves to have a thickness of 30 nm. In this case, the amount of the solution applied is set to 1g, and the substrate is rotated at 100rpm for 30 seconds from the start of the application, and then rotated at 800 to 1000rpm for the next 30 seconds. In addition, when the pigment solution is applied, an azo pigment solution is prepared using tetrafluoropropanol as a solvent, and impurities are removed by filtration with a filter. Subsequently, the substrate 1 coated with the above pigment material was dried at 70 ℃ for one hour, and then cooled at room temperature for one hour. In this way, the recording layer 2 is formed on the substrate 1 (see fig. 10 (b)).

Then, as shown in fig. 10(b), a silver alloy as the reflective layer 3 was formed on the recording layer 2 by sputtering to a thickness of 160 nm. Subsequently, a UV resin material having a thickness of 10 μm was applied on the reflective layer 3 by spin coating, and then a polycarbonate substrate (blank substrate) having a thickness of 0.6mm was placed thereon. In this state, the substrate on which each layer is formed is irradiated with UV, and the substrate on which each layer is formed and the dummy substrate are bonded to each other, thereby obtaining an optical information recording medium.

Next, the groove shape of the concave portion in the groove will be described.

The maximum depths of the pit-in-groove, and land pre-pit in the pit-in-groove region 73 were measured with a scanning probe microscope (manufactured by digital instruments). As shown in fig. 10(b), their depth is from the surface of the lands 81 of the substrate. The maximum depth dg of the grooves is 160nm and the maximum depth dp of the pits in the grooves is 260 nm. In addition, the maximum depth dlp of the land pre-pit in the groove portion was 160nm as the maximum depth of the groove. The maximum depth of the boundary trenches is 160 nm. The depths of the pits in the groove, the grooves, and the recording layer recessed portions of the 1 st land pre-pit in the pit-in-groove region 73 were measured by a scanning probe microscope manufactured by digital instruments. Here, the depth of the concave portion of the recording layer refers to the maximum amount of concavity of the recording layer 2 with respect to the surface 2a of the recording layer 2 formed on the land 81. The groove-to-groove recording layer recess depth Tg was 100nm, and the groove-to-groove recording layer recess depth Tp was 170 nm. The recording layer recess depth Tlp of land pre-pit in the groove was 90 nm.

Subsequently, the groove shape of the groove portion is explained.

The grooves of the 1 st and 2 nd groove forming portions and the depth of the SLPP were measured by a scanning probe microscope manufactured by digital instruments. As shown in FIGS. 14(a) and (b), the groove depth (height) dg was 160nm at the inner circumference and 170nm at the outer circumference. The same applies to the SLPP portion. Further, the groove forming region and the depth of the concave portion of the recording layer of the SLPP were measured by a scanning probe microscope manufactured by digital instruments. The depth of the recording layer recesses was the same as described above, the depth Tg of the recording layer recesses of the grooves was 100nm as described above, and the same applies to SLPP.

The optical information recording medium obtained in the above-described example was subjected to reproduction of a recording signal in the pit region in the groove using a laser beam having a wavelength of 650nm and a photo-detecting head having a lens with a numerical aperture of 0.6. The signal can be stably detected and reproduced. In addition, the signal modulation degree of the reproduced signal at this time was 61%, and the jitter was 7.2%, which gave good results.

In the present embodiment, as shown in fig. 15(a), although the area in which the pit 73a and the boundary groove 74a are adjacent to each other in the groove has been described, even when the groove portions of the pit and the boundary pit area in the adjacent area groove are tracked, a tracking error does not occur for the following reason. In addition to a certain degree of spot size, when tracking the boundary groove region, any boundary groove portion enters the spot because the spot is not scanned in a direction perpendicular to the tracking direction but in a direction at a gentle angle with respect to the tracking direction at the time of actual tracking. In this way, the radial push-pull signals obtained from the boundary groove region are averaged, and the disturbance of the radial push-pull signal between the pit region and the groove region in the groove at the time of tracking can be suppressed as compared with an optical information recording medium having no boundary groove region.

In addition, the following comparative example will explain that other characteristics such as reproduction errors can be satisfied in any area by dividing the recording method of the position information into the LPP of the pit portion in the groove and the SLPP of the groove portion.

In the optical information recording medium of the above-described embodiment, polycarbonate is used as the substrate, but polymethyl methacrylate, amorphous polyolefin, or the like may be used.

Comparative example

In order to confirm the superiority of the present invention, comparative examples shown below were prepared.

Comparative example 1 in which land pre-pit portion was used for both pit portion and groove portion in groove

Comparative example 2 in which SLPP method was used for both of the pit portion and the groove portion in the groove

The following table is a table comparing them with the present invention.

	Pit part in groove		Groove part (8 times speed record)
						PI error	AR	PI error	AR
The invention	30 pieces of	40％	50 are provided with	23％
					Comparative example 1	35 are provided with	43％	240 (a)	8％
Comparative example 2	900 pieces	6％	45 are provided with	22％

The PI error in the table is specified to 280 or less in the manual standard, but is preferably 100 or less and is required to 50 or less in order to ensure compatibility with various drivers. AR is specified in manual standards to be 15% or more. When the table is confirmed, the characteristics of the groove portion (user portion) in comparative example 1 do not satisfy the criteria, and the characteristics of the dimple portion in the groove do not satisfy the criteria in comparative example 2. It was confirmed that the present invention is useful in order to satisfy both the characteristics of the pit portion and the groove portion in the groove.

Finally, the form of the optical disk is explained.

Next, a specific structure of an information recording medium using the embodiment will be described. FIG. 16 shows a sector structure provided in the DVD-R. The structure of the lead-in part, the data area and the lead-out part is from the inner circle to the outside, and the data area is divided into the following parts: 030000h start. In the recording/reproducing area, the vibration is made in the radial direction at a frequency of 140kHz at a distance of about 1.3% to 2.7% with respect to the track pitch (rtackpitch), and in the present invention, the amount of vibration (wobbble) is 0.2%. When the track pitch is 0.74. mu.m, the vibration amount is about 0.015. mu.m. In the recording/reproducing area, land prepits LPPs having information such as addresses are arranged in land areas.

As shown in fig. 17, the lead-in area is composed of a start area (initial Zone), a Buffer area 0(Buffer Zone 0), an R-Physical format information area (R-Physical format information Zone), a Buffer area 1(Buffer Zone 1), a Control data area (Control data Zone), and an Extra boundary area (Extra boundary Zone) from the inner circumference of the recording/reproducing area, and has, as the Control data area (in-groove pit area) of the reproduction-dedicated area, information related to copyright protection, recording information, disc type, version, and the like, in which a groove (groove is 170nm when λ 650nm is the refractive index of the substrate) of about λ/2.4n (n: the groove) and a pit (countermeasure pit is 260nm when λ 650nm is the pit) of about λ/1.6n are provided from the land portion with respect to the recording/reproducing wavelength λ. The groove shape of the recording and reproducing area except for the control data area has a depth of about 170nm of λ/2.4 n.

In the optical information recording medium of the present invention, although the seek operation for the control data area is performed during the reproduction operation, as shown in example 2, by providing boundary pits and boundary areas such as boundary grooves for one or more tracks of the inner and outer rims adjacent to the control data area (pit in groove area), it is possible to suppress the disturbance of the radial push-pull signal and reproduce the information in the control data area without tracking failure. Further, as shown in embodiment 1, when the widths of the 1 st pit and the 2 nd pit formed longer than the 1 st pit in the control data area are in the relationship of 1 < W2/W1 < 1.2, the height of the land pre-pit side wall from the groove bottom surface is dlp, the land height from the groove bottom surface and the depth from the land bottom surface are dg, and the relationship of 0.4. ltoreq. dlp/dg < 1 is present, LPP can be detected favorably, and a reproduction error is in a favorable state.

The optical information recording medium obtained in the above-described example was subjected to reproduction of a recording signal in a control data region (pit in groove region) by using a photo-detecting head having a laser beam with a wavelength of 650nm and a lens with a numerical aperture of 0.6. The signal can be stably detected and reproduced, and in this case, the signal modulation of the reproduced signal is 61% and the jitter is 7.2%, which can provide good results.

Therefore, necessary recording measures can be surely performed at the time of recording, the condition settings of various drivers can be faithfully performed, and recording with less errors can be realized.

In addition, even when the optical recording medium of the present invention enters the data area through the control data area and the extra boundary area during the recording operation, the LPP having the address information can be detected well, and therefore, the recording operation can be performed from the physical sector number of the data area: 030000h started to be well recorded.

In the recording medium of the present invention, by providing a boundary groove region between the pit region and the groove region in the groove, it is possible to suppress a tracking error generated between the pit region and the groove region in the groove. Further, by making the in-groove pit portion LPP system and the groove portion SLPP system, it is possible to make both the in-groove pit portion and the groove portion satisfy various characteristics required by the DVD-R standard. The method for manufacturing an optical information recording medium of the present invention is useful for manufacturing an optical information recording medium of the present invention.

Claims (13)

1. An optical information recording medium having a substrate on which a plurality of lands and grooves are formed, and a recording layer and a reflective layer on the substrate, wherein the grooves include: a 1 st groove, a 2 nd groove having a pit formed therein, and a 3 rd groove having a groove width larger than that of the 1 st groove, the 3 rd groove being disposed between the 1 st groove and the 2 nd groove; pits indicating position information are formed in land portions of the region where the 2 nd groove is provided, and position information is formed by bending groove portions protruding in a tracking radial direction in the region where the 1 st and 3 rd grooves are provided.

2. The information recording medium according to claim 1, wherein the width of the 1 st groove is continuously increased from the inner circumference to the outer circumference.

3. The optical information recording medium according to claim 1 or 2, wherein the recording layer is formed of a pigment material.

4. The optical information recording medium according to claim 3, wherein the dye material is an azo dye material.

5. A method for manufacturing an optical information recording medium according to any one of claims 1 to 4, comprising: exposing a pattern corresponding to at least a 3 rd groove on a photosensitive material formed on a master disc with a 1 st exposure intensity by exposing the photosensitive material with a 1 st groove pattern, changing the pattern to a 2 nd exposure intensity higher than the 1 st exposure intensity, exposing the photosensitive material with a 3 rd exposure intensity higher than the 2 nd exposure intensity, exposing the pattern corresponding to a pit in the 2 nd groove of the photosensitive material, and making a pit exposed on a land in the 2 nd groove representing position information different from a light beam exposing the groove; developing the master after the exposure to form the pattern; forming a substrate using the master on which the pattern is formed; a recording layer and a reflective layer are formed on the substrate.

6. The method of manufacturing an optical information recording medium according to claim 5, wherein: the photosensitive material is exposed with a 1 st photosensitive intensity that continuously increases from the inner circumference toward the outer circumference.

7. The method of manufacturing an optical information recording medium according to claim 5 or 6, comprising: the photosensitive material is exposed to light at a 3 rd exposure intensity, thereby exposing the photosensitive material to light in a pattern corresponding to the pits in the 2 nd groove.

8. The method for manufacturing an optical information recording medium according to any one of claims 5 to 7, comprising: the exposure intensity was set to 0 before and after exposure of the pattern corresponding to the pit in the 2 nd groove and the 2 nd groove.

9. The method for manufacturing an optical information recording medium according to any one of claims 5 to 8, comprising: in the above development, etching is performed by reactive ion etching.

10. A method of manufacturing an optical disc according to any one of claims 1 to 4, wherein a pigment recording layer is formed by a spin coating method on a substrate injection-molded by a stamper having management information formed in advance as pits, a reflective layer is formed on the pigment recording layer, and a UV resin layer is formed on the reflective layer.

11. The method for manufacturing an optical disc according to claim 10, wherein the management information includes a write strategy.

12. A method for manufacturing an optical disc according to claim 10 or 11, wherein information relating to copyright protection is included as the management information.

13. A method for manufacturing an optical disc having lands and grooves, characterized in that a pigment recording layer is formed by a spin coating method on a substrate injection-molded by a stamper having management information formed in advance in pits, a reflective layer is formed on the pigment recording layer, and a UV resin layer is formed on the reflective layer.