JP2004158168A - Optical information recording medium and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording medium having in-groove pits on which a recording layer made of a dye material is formed, wherein the optical information recording becomes uniform in various characteristics by suppressing a change in reflectance inside and outside the medium. A medium and a method for manufacturing the medium are provided.
SOLUTION: The groove formed on the substrate of the optical information recording medium of the present invention has a groove depth that becomes continuously deeper from the inside to the outside of the medium and a groove width that becomes continuously wider. Even when a recording layer made of an organic dye material is formed on a substrate by spin coating, the height of the interface between the recording layer and the reflective layer in the groove portion extends from the inside to the outside of the optical information recording medium. The recording layer is formed so as to be substantially the same.
[Selection diagram] FIG.

Description

  The present invention relates to an optical information recording medium, and more particularly, to an optical information recording medium in which media information such as a manufacturer name and information for copyright protection measures is written in a pre-pit form.

  In recent years, DVDs (digital versatile discs) having a recording capacity several times larger than CDs (compact discs) have been widely used as information recording media for recording information such as images and sounds of movies and the like. A DVD-R (write-once digital versatile disc) that allows the user to record information only once on the DVD side, and a DVD-RW (rewritable rewritable) that allows information to be rewritten. Digital versatile disc) has already been commercialized and is expected to be widely used as a large-capacity information recording medium in the future.

  Normally, in DVD-Rs and DVD-RWs, information such as maker information of the disk and information for copyright protection measures (hereinafter referred to as media information) is stored in the innermost and outermost peripheral portions of the disk in advance. . Such media information is recorded by modifying the recording layer by light irradiation or the like using a recording device at the final stage of the disc manufacturing process. On the other hand, there is disclosed a method in which media information is not recorded on the recording layer as described above, but is recorded in advance in the form of embossed pits (hereinafter, referred to as in-groove pits) in a groove of the substrate at the stage of manufacturing the substrate of the disk. (For example, see Patent Document 1). FIG. 1 shows a part of an optical information recording medium manufactured by using this method. FIG. 1A is a partially enlarged plan view of the optical information recording medium, and schematically shows a region where an in-groove pit is formed (hereinafter, referred to as an in-groove pit region). FIGS. 1B and 1C are cross-sectional views taken along the line AA and the line BB of FIG. 1A, respectively. In this optical information recording medium, as shown in FIG. 1B, the depth from the land surface 101a of the substrate 101 on which the lands and grooves are formed to the bottom surface (lowest bottom surface) 107a of the in-groove pit 107 is used. Dp "is formed deeper than the depth dg" of the groove 105 to the bottom surface (the lowermost surface) 105a with reference to the land surface 101a. Thus, when the recording layer 102 and the reflective layer 103 are formed on the pattern forming surface of the substrate 101, the portion where the in-groove pit 107 is formed and the portion of the groove where the in-groove pit 107 is not formed are different. Then, a difference occurs in the surface height of each layer to be formed. Therefore, by utilizing the difference in depth between the in-groove pit portion and the groove portion, data such as media information can be recorded in the groove.

  By the way, in an optical information recording medium in which a recording layer is formed by applying a solution containing an organic dye by using a spin coating method, the thickness of the recording layer on the inner side (inner periphery) is larger than that on the outer side (outer periphery). Is formed such that the thickness of the recording layer is increased. This difference in thickness depends on the type of organic dye material and solvent used, but is caused by drying of the solvent at the time of spin coating or by the solution of the organic dye material developing from the inside to the outside of the substrate. As a result, the recording layer formed on the guide groove formed on the substrate surface of the medium is formed so that the outside is thicker than the inside of the medium. Due to this difference in thickness, the reflectivity fluctuates between the inside and outside of the optical information recording medium, and there is a problem that various characteristics such as the modulation factor of the push-pull signal and the recording / reproducing signal become non-uniform. As a means for solving this problem, a method is disclosed in which a groove of a substrate on which a recording layer is formed in advance is formed deeper and wider from the inner periphery to the outer periphery of the substrate (for example, see Patent Document 2).

JP-A-2001-67733 (Pages 5-6, FIG. 1-3) JP-A-2002-237100 (columns 5-6)

  When information is actually recorded / reproduced using an optical information recording medium having in-groove pits as described above, an in-groove pit area and an area in which only a groove, which is a recording area on the user side, is formed (hereinafter, referred to as an area). , A groove area), an error often occurs in which tracking is lost. This is because, as shown in FIG. 15, by forming the in-groove pits 151 on the substrate, the side walls of the adjacent lands 152 are cut off. By shaving the side wall of the adjacent land 152, the area of the upper surface of the land 152 between the in-groove pit 151 and the groove 153 becomes smaller than the area of the upper surface of the land 154 between the normal grooves 153. Accordingly, the areas of the recording layer and the reflective layer formed on the land 152 and the land 154 are different. When the groove 153 between the land 152 and the land 154 is tracked by the light spot SP, even if the light spot SP is located at the center of the groove 153, the light amount of the reflected light RF1 obtained from the land 154 and the land 152 A difference occurs between the reflected light RF2 and the amount of reflected light RF2, and the radial push-pull signal is offset. As a result, good tracking of the groove cannot be performed, which causes an increase in jitter and a decrease in the degree of modulation. In some cases, tracking may be lost.

  In the actual detection of the radial push-pull signal, when an optical pickup having a wavelength λ = 650 nm and a numerical aperture NA = 0.6 is used, a light spot having a diameter of about 1 μm scans the optical information recording medium in a radial direction. . At this time, since the optical information recording medium is rotating at a high speed, the light spot is not scanned in a direction perpendicular to the tracking direction but in a direction forming a gentle angle with respect to the tracking direction. . Since the radial push-pull signal does not have such a frequency characteristic that the pit can be resolved and detected, the in-groove pit portion formed deeper than the groove is equivalent to detecting a wide groove. . Therefore, in this case, the width of the groove has changed extremely at the boundary between the in-groove pit area and the groove area, and the radial push-pull signal is disturbed.

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

  A substrate of an optical information recording medium having in-groove pits is usually manufactured using a master that has been etched using an RIE apparatus. However, when a groove is formed on the surface of the master by etching using a normal RIE apparatus, The depth of the formed groove is substantially constant. It has been difficult to form a groove that continuously becomes deeper from the inside to the outside on the surface of the master using such an RIE apparatus.

  Therefore, an object of the present invention is to provide an optical information recording medium capable of obtaining a stable radial push-pull signal even when tracking the boundary between the in-groove pit area and the groove area, and a method of manufacturing the same. It is in.

  Another object of the present invention is to provide an optical information recording medium having in-groove pits, on which a recording layer made of a dye material is formed, wherein various kinds of optical information recording media are suppressed by suppressing reflectance fluctuation between inside and outside of the medium. An object of the present invention is to provide an optical information recording medium having uniform characteristics and a method for manufacturing the same.

According to a first aspect of the present invention, there is provided an optical information recording medium having a substrate on which a plurality of lands and grooves are formed, and a recording layer containing an organic dye and a reflective layer on the substrate,
The groove is a first groove;
A second groove in which pits are formed;
A third groove in which a pit narrower than the pit of the second groove is formed;
A third groove is disposed between the first groove and the second groove;
A groove width such that the first groove, the second groove, and the third groove are continuously deepened from the inside to the outside of the optical information recording medium, and are continuously widened. An optical information recording medium characterized by being formed by:

  A plurality of lands and grooves are formed on the substrate of the optical information recording medium of the present invention, and pits (in-groove pits) are formed in some of the grooves. An in-groove pit narrower than the above-described in-groove pit is further formed at a boundary between the area where the in-groove pit is formed (the in-groove pit area) and the area where only the groove is formed (the groove area). (Hereinafter, referred to as a boundary pit area). As a result, a gradual change in shape is obtained from the in-groove pit region to the groove region on the substrate surface. Therefore, in the optical information recording medium using this substrate, even when tracking is performed so as to straddle the boundary between the region where the in-groove is formed and the region where only the groove is formed, the radial push-pull signal is disturbed. And stable tracking can be performed. Further, the groove formed on the substrate of the optical information recording medium of the present invention is formed with a groove depth that continuously increases from the inside to the outside of the medium and with a groove width that continuously increases. Have been. As a result, even when a recording layer made of an organic dye material is formed on a substrate by spin coating, the height of the interface between the recording layer and the reflective layer in the groove portion is generally substantially from the inside to the outside of the optical information recording medium. The recording layer can be formed to be the same.

  In the optical information recording medium of the present invention, the half value width of the first groove located inside the optical information recording medium is represented by Wgi, and the half value width of the first groove located outside the optical information recording medium is represented by Wgo. When the half width of the pits of the second groove is represented by Wp and the half width of the pits of the third groove is represented by Wpb, it is preferable that Wgi <Wgo ≦ Wpb <Wp. Further, it is desirable that the ratio Wp / Wpb of the half width Wp to the half width Wpb satisfies 1.05 ≦ Wp / Wpb ≦ 1.15. When Wp / Wpb <1.05, the radial push-pull signal in the first groove tends to be offset or disturbed, and when Wp / Wpb is 1.15 <Wp / Wpb, the radial push-pull signal from the in-groove pit formed in the third groove is disturbed. This is not desirable because the signal modulation degree becomes low.

  In the optical information recording medium of the present invention, the depth from the substrate surface of the first groove located inside the optical information recording medium is represented by dgi, and the substrate surface of the first groove located outside the optical information recording medium is represented by dgi. When the depth from is expressed by dgo, it is desirable that the ratio dgo / dgi between the depth dgi and the depth dgo satisfies 1.00 <dgo / dgi ≦ 1.10. If dgo / dgi ≦ 1.00, the depth of the depression of the recording layer corresponding to the groove portion becomes shallower from the inside to the outside of the optical information recording medium. As a result, the push-pull signal decreases toward the outside of the medium, and the balance between the inside and outside of the medium is lost. When dgo / dgi> 1.10, the depth of the pit of the recording layer corresponding to the groove portion increases from the inside to the outside of the optical information recording medium. As a result, the push-pull signal increases toward the outside of the medium, and the balance between the inside and outside of the medium is lost. Further, if dgo / dgi> 1.10, the groove portion outside the medium is too deep, so that the light reflectance of the groove portion decreases.

  In the present invention, it is desirable that the ratio Wgo / Wgi of the half width Wgi to the half width Wgo satisfies 1.03 ≦ Wgo / Wgi ≦ 1.10. If Wgo / Wgi <1.03, the depth of the depression of the recording layer corresponding to the groove portion becomes shallower from the inside to the outside of the optical information recording medium, and the width of the depression becomes narrow. As a result, the push-pull signal is reduced and the recording density is reduced as the position is outside the medium, and the balance is lost between the inside and the outside of the medium. When Wgo / Wgi> 1.10, the depth of the depression of the recording layer corresponding to the groove portion increases from the inside to the outside of the optical information recording medium, and the width of the depression increases. As a result, the push-pull signal becomes larger and the recording density also becomes larger toward the outside, and the balance is lost between the inside and the outside of the medium. In the present invention, the recording layer made of a dye material can be formed so that the height of the interface between the recording layer and the reflective layer in the groove portion is substantially the same in the entire optical information recording medium.

  In the present invention, the depth of the depression of the recording layer from the interface between the recording layer and the reflective layer on the land surface to the interface between the recording layer and the reflective layer in the first groove located inside the optical information recording medium is defined as Tgi. Where Tgo is the depth of the recess of the recording layer from the interface between the recording layer and the reflective layer on the land surface to the interface between the recording layer and the reflective layer in the first groove located outside the optical information recording medium. And the depth of the pit of the recording layer from the interface between the recording layer and the reflective layer in the pit of the second groove from the interface between the recording layer and the reflective layer on the land surface is represented by Tp. It is preferable that Tgi = Tgo <Tpb <Tp, where Tpb represents the depth of the depression of the recording layer from the interface between the recording layer and the reflection layer in the pit of the third groove from the interface between the recording layer and the reflection layer. This makes it possible to reduce disturbance of the radial push-pull signal.

In the present invention, the pits formed in the same groove of the groove are composed of a first pit and a second pit whose length in the groove direction is longer than the first pit, and the substrate radius at the first pit is smaller than the first pit. When the maximum width in the direction is represented by W ₁ and the maximum width in the substrate radial direction of the second pit is represented by W ₂ , it is preferable that 1 ≦ W ₂ / W ₁ <1.2.

  In the present invention, the organic dye material is preferably an azo dye material.

According to a second aspect of the present invention, there is provided a method of manufacturing an optical information recording medium according to the first aspect,
By irradiating the photosensitive material formed on the master with an exposure intensity that continuously changes from the inside to the outside of the master, the first groove, the second groove, and the third groove are applied to the photosensitive material. Exposing a pattern corresponding to pits of a second groove and a pit of a third groove to the photosensitive material by exposing a pattern corresponding to the groove of the groove and irradiating the photosensitive material at two different exposure intensities;
Forming a pattern corresponding to the first groove, the pitted second groove, and the pitted third groove by performing development and etching by RIE on the master after the exposure;
Forming a substrate using the master on which the pattern is formed;
Forming a recording layer and a reflective layer on the substrate; and a method for manufacturing an optical information recording medium, comprising:

  By using the manufacturing method of the present invention, the optical information recording medium according to the first aspect of the present invention can be manufactured.

  In the method for manufacturing an optical information recording medium according to the present invention, the exposure intensity when exposing the pattern corresponding to the pit is first set to the first exposure intensity, and then set to the second exposure intensity lower than the first exposure intensity. It is desirable to change to the first exposure intensity. Thereby, even when an in-groove pit having a long pit length is formed, the width in the substrate radial direction can be suppressed from expanding. This is because, when the master is exposed, by reducing the integrated exposure amount during the exposure at the second exposure intensity, a substantially constant integrated exposure amount can be given through the pits. Further, when a clock cycle for reproducing the optical information recording medium is represented by T, it is desirable to set each of the exposure periods at the first exposure intensity to 1T to 1.5T. Further, it is desirable that the exposure of the master should include setting the exposure intensity to 0 in addition to the exposure intensity.

  In the present invention, it is preferable that the etching by RIE is performed by changing the flow rate of the gas used for RIE between the inside and outside of the master. Thereby, the portion corresponding to the groove formed on the master can be formed so as to be deeper from the inside to the outside of the master by using RIE.

According to a third aspect of the present invention, there is provided an optical information recording medium having a substrate on which a plurality of lands and grooves are formed, and a recording layer containing an organic dye and a reflective layer on the substrate,
The groove is a first groove;
A second groove wider than the first groove;
A third groove in which pits are formed;
A second groove is disposed between the first and third grooves;
The first and third grooves are formed so as to have a groove depth that continuously increases from the inside to the outside of the optical information recording medium and a groove width that continuously increases. An optical information recording medium is provided.

  A plurality of lands and grooves are formed on the substrate of the optical information recording medium of the present invention, and in-groove pits are formed in some of the grooves. Further, at the boundary between the in-groove pit region and the groove region, a region (hereinafter, referred to as a boundary groove region) in which a groove (boundary groove) wider than a normal groove is formed is provided. In an optical information recording medium using this substrate, the change in the groove width between adjacent grooves from the in-groove pit area to the groove area is more gradual than in an optical information recording medium in which only in-groove pits and grooves are formed. Therefore, disturbance of the radial push-pull signal is small, and stable tracking can be performed. Further, the groove formed on the substrate of the optical information recording medium of the present invention is formed with a groove depth that continuously increases from the inside to the outside of the medium and with a groove width that continuously increases. Have been. As a result, even when a recording layer made of an organic dye material is formed on a substrate by spin coating, the height of the interface between the recording layer and the reflective layer in the groove portion is generally substantially from the inside to the outside of the optical information recording medium. The recording layer can be formed to be the same.

  In the optical information recording medium of the present invention, the half value width of the first groove located inside the optical information recording medium is represented by Wgi, and the half value width of the first groove located outside the optical information recording medium is represented by Wgo. When the half width of the second groove is represented by Wgb and the half width of the pits of the third groove is represented by Wp, it is preferable that Wgi <Wgo ≦ Wgb ≦ Wp.

  In the optical information recording medium of the present invention, the depth from the substrate surface of the first groove located inside the optical information recording medium is represented by dgi, and the substrate surface of the first groove located outside the optical information recording medium is represented by dgi. When the depth from is expressed by dgo, it is desirable that the ratio dgo / dgi between the depth dgi and the depth dgo satisfies 1.00 <dgo / dgi ≦ 1.10. If dgo / dgi ≦ 1.00, the depth of the depression of the recording layer corresponding to the groove portion becomes shallower from the inside to the outside of the optical information recording medium. As a result, the push-pull signal decreases toward the outside of the medium, and the balance between the inside and outside of the medium is lost. When dgo / dgi> 1.10, the depth of the pit of the recording layer corresponding to the groove portion increases from the inside to the outside of the optical information recording medium. As a result, the push-pull signal increases toward the outside of the medium, and the balance between the inside and outside of the medium is lost. Further, if dgo / dgi> 1.10, the groove portion outside the medium is too deep, so that the light reflectance of the groove portion decreases.

  In the present invention, it is desirable that the ratio Wgo / Wgi of the half width Wgi to the half width Wgo satisfies 1.03 ≦ Wgo / Wgi ≦ 1.10. If Wgo / Wgi <1.03, the depth of the depression of the recording layer corresponding to the groove portion becomes shallower from the inside to the outside of the optical information recording medium, and the width of the depression becomes narrow. As a result, the push-pull signal is reduced and the recording density is reduced as the position is outside the medium, and the balance is lost between the inside and the outside of the medium. When Wgo / Wgi> 1.10, the depth of the depression of the recording layer corresponding to the groove portion increases from the inside to the outside of the optical information recording medium, and the width of the depression increases. As a result, the push-pull signal becomes larger and the recording density also becomes larger toward the outside, and the balance is lost between the inside and the outside of the medium. In the present invention, the recording layer made of a dye material can be formed so that the height of the interface between the recording layer and the reflective layer in the groove portion is substantially the same in the entire optical information recording medium.

In the present invention, the depth of the depression of the recording layer from the interface between the recording layer and the reflective layer on the land surface to the interface between the recording layer and the reflective layer in the first groove located inside the optical information recording medium is defined as Tgi. Where Tgo is the depth of the recess of the recording layer from the interface between the recording layer and the reflective layer on the land surface to the interface between the recording layer and the reflective layer in the first groove located outside the optical information recording medium. Where Tgb is the depth of the recess of the recording layer from the interface between the recording layer and the reflective layer on the land surface from the interface between the recording layer and the reflective layer in the second groove. It is desirable that Tgi = Tgo <Tgb <Tp, where Tp represents the depression depth of the recording layer from the interface with the layer to the interface between the recording layer and the reflective layer in the pit of the third groove. The pits formed in the same groove of the groove are composed of a first pit and a second pit whose length in the groove direction is longer than the first pit. When the maximum width is represented by W ₁ and the maximum width of the second pit in the substrate radial direction is represented by W ₂ , it is preferable that 1 ≦ W ₂ / W ₁ <1.2.

  In the present invention, the organic dye material is preferably an azo dye material.

According to a fourth aspect of the present invention, there is provided a method of manufacturing an optical information recording medium according to the third aspect,
By irradiating the photosensitive material formed on the master with an exposure intensity that continuously changes from the inside to the outside of the master, the photosensitive material corresponds to the grooves of the first groove and the third groove. Exposing a pattern corresponding to pits of a second groove and a third groove to the photosensitive material by exposing the pattern and irradiating the photosensitive material at two different exposure intensities;
Forming a pattern corresponding to the first groove, the second groove, and the pitted third groove by performing development and etching by RIE on the master after the exposure;
Forming a substrate using the master on which the pattern is formed;
Forming a recording layer and a reflective layer on the substrate; and a method for manufacturing an optical information recording medium, comprising:

  By using the manufacturing method of the present invention, the optical information recording medium of the third aspect of the present invention can be manufactured.

  In the present invention, the exposure intensity when exposing the pattern corresponding to the pit is first set to the first exposure intensity, then to the second exposure intensity lower than the first exposure intensity, and further to the first exposure intensity. It is desirable to change. Thereby, even when an in-groove pit having a long pit length is formed, the width in the substrate radial direction can be suppressed from expanding. Further, when a clock cycle for reproducing the optical information recording medium is represented by T, it is desirable to set each of the exposure periods at the first exposure intensity to 1T to 1.5T. Further, it is desirable that the exposure of the master should include setting the exposure intensity to 0 in addition to the exposure intensity. Further, it is preferable that the etching by RIE is performed by changing the flow rate of the gas used for RIE between the inside and outside of the master.

According to a fifth aspect of the present invention, there is provided an optical information recording medium having a substrate on which a plurality of lands and grooves are formed, and a recording layer containing an organic dye and a reflective layer on the substrate,
The groove is a first groove;
A second groove wider than the first groove;
A third groove in which pits are formed;
And a fourth groove in which a pit narrower than the pit of the third groove is formed.
The first to fourth grooves are arranged in the order of a first groove, a second groove, a fourth groove, and a third groove,
A groove width such that the first groove, the third groove, and the fourth groove are continuously deepened from the inside to the outside of the optical information recording medium, and are continuously widened. An optical information recording medium characterized by being formed by:

  A plurality of lands and grooves are formed on the substrate of the optical information recording medium of the present invention, and in-groove pits are formed in some of the grooves. A boundary pit region is provided between the in-groove pit region and the groove region, and a boundary groove wider than a normal groove is provided between the boundary pit region and the groove region. In the optical information recording medium using this substrate, by providing the boundary groove region, the width of the adjacent grooves is gradually changed from the groove region to the boundary pit region. In comparison, disturbance of the radial push-pull signal can be further suppressed. Further, since the boundary groove area is provided between the groove area and the boundary pit area, the size of the in-groove pit in the boundary pit area can be made larger than when no boundary groove area exists. This makes it possible to obtain a reproduced signal having a high degree of modulation from the in-groove pits in the boundary pit area. Further, the groove formed on the substrate of the optical information recording medium of the present invention is formed with a groove depth that continuously increases from the inside to the outside of the medium and with a groove width that continuously increases. Have been. As a result, even when a recording layer made of an organic dye material is formed on a substrate by spin coating, the height of the interface between the recording layer and the reflective layer in the groove portion is generally substantially from the inside to the outside of the optical information recording medium. The recording layer can be formed to be the same.

  In the optical information recording medium of the present invention, the half value width of the first groove located inside the optical information recording medium is represented by Wgi, and the half value width of the first groove located outside the optical information recording medium is represented by Wgo. When the half width of the second groove is represented by Wgb, the half width of the pit of the third groove is represented by Wp, and the half width of the pit of the fourth groove is represented by Wpb, Wgi <Wgo ≦ Wgb ≦ Wpb <Wp It is desirable that Further, it is desirable that the ratio Wp / Wpb of the half width Wp to the half width Wpb satisfies 1.05 ≦ Wp / Wpb ≦ 1.15. As described above, when Wp / Wpb <1.05, the radial push-pull signal in the first groove is likely to have an offset or disturbance, and when Wp / Wpb is 1.15 <Wp / Wpb, the radial push-pull signal is formed in the third groove. This is not desirable because the degree of signal modulation from the groove pits is low.

  In the optical information recording medium of the present invention, the depth from the substrate surface of the first groove located inside the optical information recording medium is represented by dgi, and the substrate surface of the first groove located outside the optical information recording medium is represented by dgi. When the depth from is expressed by dgo, it is desirable that the ratio dgo / dgi between the depth dgi and the depth dgo satisfies 1.00 <dgo / dgi ≦ 1.10. If dgo / dgi ≦ 1.00, the depth of the depression of the recording layer corresponding to the groove portion becomes shallower from the inside to the outside of the optical information recording medium. As a result, the push-pull signal decreases toward the outside of the medium, and the balance between the inside and outside of the medium is lost. When dgo / dgi> 1.10, the depth of the pit of the recording layer corresponding to the groove portion increases from the inside to the outside of the optical information recording medium. As a result, the push-pull signal increases toward the outside of the medium, and the balance between the inside and outside of the medium is lost. Further, if dgo / dgi> 1.10, the groove portion outside the medium is too deep, so that the light reflectance of the groove portion decreases.

  In the present invention, it is desirable that the ratio Wgo / Wgi of the half width Wgi to the half width Wgo satisfies 1.03 ≦ Wgo / Wgi ≦ 1.10. If Wgo / Wgi <1.03, the depth of the depression of the recording layer corresponding to the groove portion becomes shallower from the inside to the outside of the optical information recording medium, and the width of the depression becomes narrow. As a result, the push-pull signal is reduced and the recording density is reduced as the position is outside the medium, and the balance is lost between the inside and the outside of the medium. When Wgo / Wgi> 1.10, the depth of the depression of the recording layer corresponding to the groove portion increases from the inside to the outside of the optical information recording medium, and the width of the depression increases. As a result, the push-pull signal becomes larger and the recording density also becomes larger toward the outside, and the balance is lost between the inside and the outside of the medium. In the present invention, the recording layer made of a dye material can be formed so that the height of the interface between the recording layer and the reflective layer in the groove portion is substantially the same in the entire optical information recording medium.

  In the present invention, the depth of the depression of the recording layer from the interface between the recording layer and the reflective layer on the land surface to the interface between the recording layer and the reflective layer in the first groove located inside the optical information recording medium is defined as Tgi. Where Tgo is the depth of the recess of the recording layer from the interface between the recording layer and the reflective layer on the land surface to the interface between the recording layer and the reflective layer in the first groove located outside the optical information recording medium. Where Tgb is the depth of the recess of the recording layer from the interface between the recording layer and the reflective layer on the land surface from the interface between the recording layer and the reflective layer in the second groove. The depth of the depression of the recording layer from the interface with the recording layer to the interface between the recording layer and the reflection layer in the pits of the third groove is represented by Tp, and the depth of the fourth groove from the interface between the recording layer and the reflection layer on the land surface described above. Recording in the pit And a recess depth of the recording layer from the interface between the reflective layer when expressed in Tpb, it is desirable that Tgi = Tgo <Tgb <Tpb <Tp. This makes it possible to reduce disturbance of the radial push-pull signal.

In the present invention, the pits formed in the same groove of the groove are composed of a first pit and a second pit whose length in the groove direction is longer than the first pit, and the substrate radius at the first pit is smaller than the first pit. When the maximum width in the direction is represented by W ₁ and the maximum width in the substrate radial direction of the second pit is represented by W ₂ , it is preferable that 1 ≦ W ₂ / W ₁ <1.2.

  In the present invention, the organic dye material is preferably an azo dye material.

According to a sixth aspect of the present invention, there is provided a method of manufacturing an optical information recording medium according to the fifth aspect,
By irradiating the photosensitive material formed on the master with an exposure intensity that continuously changes from the inside to the outside of the master, the first groove, the third groove, and the fourth groove are applied to the photosensitive material. The pattern corresponding to the grooves of the second groove, the pits of the third groove, and the pits of the fourth groove are exposed on the photosensitive material by irradiating the pattern corresponding to the groove of the groove and irradiating the photosensitive material with three different exposure intensities. To do;
Forming a pattern corresponding to the first groove, the second groove, the pitted third groove and the pitted fourth groove by performing development and etching by RIE on the master after the exposure;
Forming a substrate using the master on which the pattern is formed;
Forming a recording layer and a reflective layer on the substrate; and a method for manufacturing an optical information recording medium, comprising:

  The optical information recording medium according to the fifth aspect of the present invention can be manufactured by using the manufacturing method of the present invention.

  In the method for manufacturing an optical information recording medium according to the present invention, the exposure intensity when exposing the pattern corresponding to the pit is first set to the first exposure intensity, and then set to the second exposure intensity lower than the first exposure intensity. It is desirable to change to the first exposure intensity. Thereby, even when an in-groove pit having a long pit length is formed, the width in the substrate radial direction can be suppressed from expanding. This is because, when the master is exposed, by reducing the integrated exposure amount during the exposure at the second exposure intensity, a substantially constant integrated exposure amount can be given through the pits. Further, when a clock cycle for reproducing the optical information recording medium is represented by T, it is desirable to set each of the exposure periods at the first exposure intensity to 1T to 1.5T. Further, it is desirable that the exposure of the master should include setting the exposure intensity to 0 in addition to the exposure intensity.

  In the present invention, it is preferable that the etching by RIE is performed by changing the flow rate of the gas used for RIE between the inside and outside of the master. Thus, a portion corresponding to a groove formed on the master can be formed so as to be deeper from the inside to the outside of the master by using RIE.

  According to the present invention, there is provided a master used in the method for manufacturing an optical information recording medium according to the above aspect, wherein the master is formed of glass. Further, the present invention provides a stamper manufactured using a master used in the method for manufacturing an optical information recording medium according to the above aspect.

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

[Method of producing master and stamper for substrate production]
As shown in FIG. 7, the substrate of the optical information recording medium according to the present invention includes a groove area 71, a boundary pit area 72, an in-groove pit area 73, a boundary pit area 74, and a groove area in this order from the inner peripheral side of the substrate 1. 75 are formed. A method of manufacturing a master and a stamper for manufacturing the substrate 1 will be described with reference to FIGS. As shown in FIG. 2A, a glass master 50 having a diameter of 200 mm and a thickness of 6 mm was prepared. Next, as shown in FIG. 2B, a photoresist 52 was uniformly applied to a thickness of 200 nm on one surface 50a of the glass master 50 by spin coating. Next, the glass master 50 on which the photoresist 52 was formed was mounted on a cutting device (not shown). The cutting device mainly includes a Kr gas laser light source that oscillates a laser beam having a wavelength of 351 nm, a light modulator including an acoustic light modulation element, a condenser lens, a driving device for rotating a glass master, and the like. As shown in FIG. 2C, a laser beam LS emitted from a laser light source (not shown) of the cutting device irradiates a photoresist 52 on a glass master 50 via an optical modulator and a condenser lens. Is done. At this time, the glass master 50 was rotated at a predetermined rotation speed with reference to the central axis AX of the glass master 50. The irradiation position of the laser beam LS on the glass master 50 moves from the inside to the outside of the glass master 50 along the radial direction of the glass master 50 (arrow AR2).

  As described above, while moving the laser beam LS on the glass master 50, the exposure intensity of the laser light LS applied to the glass master 50 is changed using the optical modulator. In the present embodiment, as shown in FIG. 3, the exposure intensity of the laser beam was changed into three levels of low level, middle level and high level. A region having a radius of 19.0 mm to 24.0 mm with respect to the center axis (AX) of the glass master corresponds to a groove region 71 of the substrate 1 shown in FIG. 7 (hereinafter, referred to as a first groove forming region). A region having a radius of 24.0 mm to 24.1 mm corresponds to the in-groove pit region 73 of the substrate 1 (hereinafter, referred to as an in-groove pit formation region). Further, an area having a radius of 24.1 mm to 58.9 mm is a user data area and corresponds to the groove area 75 of the substrate 1 (hereinafter, referred to as a second groove forming area). As shown in FIG. 3, the exposure intensity in the first and second groove formation regions was set to a low level (hereinafter, referred to as a groove level). In the in-groove pit formation region, the exposure intensity for forming the in-groove pit was set to a high level (hereinafter, referred to as the in-groove pit level), and the exposure intensity for the other groove portions was set to the groove level. Further, regions formed by in-groove pits each corresponding to one track (hereinafter referred to as boundary pit formation regions) were provided at the boundaries between the first and second groove formation regions and the in-groove pit formation regions. This boundary pit formation region corresponds to the boundary pit regions 72 and 74 of the substrate 1 shown in FIG. The exposure intensity when forming the in-groove pits in the boundary pit formation region was set to a medium level (hereinafter, referred to as a boundary pit level), and the exposure intensity for the other groove portions was set to the groove level. In this embodiment, when the in-groove pit level is 100%, the boundary pit level is set to 90% and the groove level is set to 55%. Each in-groove pit formed in the boundary pit formation region is formed with a channel bit length of 3T to 11T or 14T (T: clock cycle) in the tangential direction of the track. The pattern of the boundary pits formed in one track may be a random pattern. Further, the shortest channel bit length can be adjusted according to the reproducing apparatus used. Further, in this embodiment, when the exposure intensity is changed during the exposure, as shown in FIG. 3, each time the exposure intensity is switched, a period in which the exposure intensity of the laser beam is temporarily set to the 0 level is provided. Thereby, the processing accuracy of the in-groove pit portion in the in-groove pit formation region and the boundary pit formation region of the glass master is improved.

  Next, the glass master to which the photoresist was exposed was taken out of the cutting device and developed. Thus, a groove forming section 40, a boundary pit forming section 42, and an in-groove pit forming section 44 as shown in FIGS. 4A and 4B were formed on the glass master 50. The groove forming portion 40 is formed so that the cross section has a V-shaped groove shape. Further, in the boundary pit forming section 42 and the in-groove pit forming section 44, the photoresist 52 on the glass master 50 is removed by a developing process, and the surface 50a of the glass master 50 is exposed as shown in FIG. It appears as a part 42a and an exposed part 44a. The width of the exposed portion 42 a in the glass master disk radial direction is smaller than the width of the exposed portion 44 a of the in-groove pit forming portion 44.

Next, as shown in FIG. 5A, the surface of the photoresist 52 formed on the glass master 50 is exposed to a C ₂ F ₆ gas using a RIE (reactive ion etching) device (not shown). Etching was performed in an atmosphere. As a result, the in-groove pit forming portion 44 and the boundary pit forming portion 42 are respectively etched to a depth of 90 nm from the surface 50a of the glass master 50. Then, as shown in FIG. 5 (b), in order to expose the surface 50a of the glass master disk 50 in the groove forming part 40, using a resist ashing apparatus according to O ₂ (not shown), the photoresist 52 a predetermined thickness only Shaved. Thus, the glass master disk surface 50a of the groove forming portion 40 was exposed. Further, as shown in FIG. 5C, RIE was performed again on the surface of the glass master 50 on which the photoresist 52 was formed in a C ₂ F ₆ gas atmosphere. As a result, the groove forming portion 40 was etched to a depth of 170 nm from the glass master disk surface 50a. At the same time, the in-groove pit forming section 44 and the boundary pit forming section 42 were etched to a depth of 260 nm from the glass master surface 50a. Next, as shown in FIG. 5D, the photoresist 52 on the glass master 50 was removed again by using a resist ashing apparatus (not shown). Thus, a glass master 50 having a desired pattern formed on the surface was obtained.

  The pattern forming surface of the glass master 50 was subjected to electroless plating as a pretreatment for plating. Further, by using this plating layer as a conductive film, a Ni layer having a thickness of 0.29 mm was formed by electroforming. Next, the surface of the Ni layer formed on the glass master 50 was polished, and the Ni layer was separated from the glass master to obtain a stamper. The formation of the conductive film in the pretreatment of the plating may be performed by a sputtering method or an evaporation method.

[Method of manufacturing information recording medium]
The stamper was mounted on an existing injection molding apparatus, and a substrate 1 was obtained by injection molding. The substrate 1 is a polycarbonate substrate having a diameter of 120 mm and a thickness of 0.6 mm, and a pattern having the same shape as the concavo-convex pattern formed on the glass master is formed on one surface of the substrate 1 as shown in FIG. Transcribed. As described above, the groove area 71, the boundary pit area 72, the in-groove pit area 73, the boundary pit area 74, and the groove area (user data area) 75 are formed on the substrate 1 as shown in FIG. A solution having a concentration of 1% by weight of an azo dye represented by the following chemical formula (1) was applied onto the pattern forming surface of the substrate 1 by spin coating. At this time, the solution was applied so as to have a thickness of 100 nm in the groove portion. In applying the above-mentioned dye solution, tetrafluoropropanol was used as a solvent to obtain an azo dye solvent, and the solution was filtered through a filter to remove impurities. Next, the substrate 1 coated with the dye material was dried at 70 ° C. for 1 hour, and further cooled at room temperature for 1 hour. Thus, the recording layer 2 was formed on the substrate 1 (see FIG. 8B).

  Further, as shown in FIG. 8B, an Ag alloy was formed as a reflective layer 3 on the recording layer 2 by a sputtering method so as to have a thickness of 160 nm. Next, a UV resin material was applied on the reflective layer 3 by spin coating, and a 0.6 mm-thick polycarbonate substrate (dummy substrate) was placed thereon. In this state, the substrate on which each layer was formed was subjected to UV irradiation, whereby the substrate on which each layer was formed and the dummy substrate were bonded to obtain an optical information recording medium.

  With respect to the optical information recording medium thus obtained, the maximum depth of the in-groove pit portion of the in-groove pit region 73, the boundary pit portion of the boundary pit region 74, and the groove portion of the groove region 75 are determined using an AFM manufactured by Digital Instruments. It was measured. These depths were, as shown in FIG. 8B, the depth from the surface of the land 80 of the substrate. The maximum depth dg of the groove portion was 170 nm. The maximum depth dpb of the boundary pit portion was 260 nm. Further, the maximum depth dp of the in-groove pit portion was 260 nm. The maximum depth dg of the groove portion and the maximum depth dp of the in-groove pit portion satisfy the condition of 1.4 ≦ dp / dg ≦ 1.7 in order to obtain good recording / reproducing signal characteristics such as good signal modulation and jitter. It is desirable to satisfy This is a condition determined based on experiments performed by the present inventors, and the optical information recording medium according to the present embodiment is designed to satisfy this condition. Further, with reference to the surface of the land 80, the half width Wp of the in-groove pit portion of the in-groove pit region 73, the half width Wpb of the boundary pit portion of the boundary pit region 74, and the half width Wg of the groove portion of the groove region 75 are calculated by Each was measured using an AFM manufactured by Digital Instruments. Here, the half-value width refers to the groove width or hole width in the radial direction of the medium at a position at a half depth of the maximum depth in each part with the surface of the land 80 as a reference plane. The half width Wg was 320 nm, the half width Wpb was 350 nm, and the half width Wp was 400 nm. This shows that the relationship of Wg ≦ Wpb <Wp holds. Further, the ratio Wp / Wpb of the half-value width Wp to the half-value width Wpb = 1.14, which satisfies the condition of 1.05 ≦ Wp / Wpb ≦ 1.15.

  Further, as shown in FIG. 8B, the recording layer depressions in the in-groove pit portion of the in-groove pit region 73, the boundary pit portion of the boundary pit region 74, and the groove portion of the groove region 75 of the obtained optical information recording medium. The depth was measured using an AFM manufactured by Digital Instruments. Here, the recording layer depression depth refers to the maximum depression amount of the recording layer 2 based on the surface 2a of the recording layer 2 formed on the land 80. The recording layer depression depth Tp in the in-groove pit region 73 was 170 nm. The recording layer depression depth Tpb in the boundary pit region 74 was 135 nm. The recording layer depression depth Tg of the groove region 75 was 100 nm. The recording layer depression depth Tp and the recording layer depression depth Tg must satisfy the following condition: 1.6 ≦ Tp / Tg ≦ 2.0 in order to obtain good recording / reproducing signal characteristics such as good signal modulation and jitter. Is desirable. This is a condition determined based on experiments performed by the present inventors, and the optical information recording medium according to the present embodiment is designed to satisfy this condition. The conditions of the recording layer depression depth Tpb in the boundary pit area 74 and the recording layer depression depth Tp in the in-groove pit area 73 or the recording layer depression depth Tg in the groove area 75 are determined in the recording of the boundary pit area 74. Tg <Tpb <Tp because the layer depression depth Tpb reduces the difference between the recording layer depression depth Tg of the groove region 75 and the recording layer depression depth Tp of the in-groove pit region 73. Further, the ratio of the maximum depth dp of the in-groove pit portion to the maximum depth dg of the groove portion and the ratio of the recording layer depression depth Tp to the recording layer depression depth Tg satisfy the condition of dp / dg <Tp / Tg. It is desirable. Even if the maximum depth dp of the in-groove pit is not a condition that a sufficient signal modulation degree or a radial push-pull signal is obtained with respect to the maximum depth dg of the groove portion, a dye material is applied as a recording layer on the substrate. By doing so, the difference between the optical path length of the laser light in the groove portion and the optical path length of the laser light in the in-groove pit portion at the time of recording information reproduction can be enlarged, and the optical path length difference can be increased. Thereby, a sufficient signal modulation degree and a radial push-pull signal can be obtained.

  The recorded information in the in-groove pit area was reproduced from the optical information recording medium obtained in the above example by using an optical pickup having a laser beam having a wavelength of 650 nm and a lens having a numerical aperture of 0.6. The detection and reproduction of the signal could be performed stably. At this time, the signal modulation degree of the reproduced signal was 61% and the jitter was 7.2%, and good results were obtained in each case.

  In the present embodiment, as shown in FIG. 8A, the region where the in-groove pit 73a and the boundary pit 74a are adjacent to each other has been described, but the groove portion in the in-groove pit and the boundary pit region is adjacent to each other. Even during tracking, no tracking error occurs for the following reason. In addition to the light spot having a certain spot size, in actual tracking, the light spot is scanned not at right angles to the tracking direction but at a gentle angle, so In the case of tracking, one of the boundary pits is included in the light spot. As a result, the radial push-pull signal obtained from the boundary pit area is averaged, and compared with the optical information recording medium in which only the groove and the in-groove pit are formed, the distance between the in-groove pit area and the groove area during tracking is reduced. The disturbance of the radial push-pull signal can be suppressed.

Comparative Example 1
Next, a comparison result between the radial push-pull signal output of the optical information recording medium manufactured in the above embodiment and the radial push-pull signal output of the conventional information recording medium having in-groove pits is shown. FIG. 9A shows a detection result of the optical information recording medium manufactured in the above-described embodiment. The output of the sum signal sa from the two-segment detector of the optical pickup at the time of seeking is shown in the upper part, and the difference signal ( 3 shows the output of a radial push-pull signal) ppa. FIG. 9B shows a result of detection of a conventional optical information recording medium having in-groove pits. The upper part shows the output of the sum signal sb during seek, and the lower part shows the difference signal (radial push-pull signal) ppb. The output is shown respectively. 9 (a) and 9 (b), where the amplitude levels of the sum signals sa and sb greatly change (represented by reference numeral 9a in FIG. 9 (a) and reference numeral 9b in FIG. 9 (b), respectively). Is the boundary between the in-groove pit area and the groove area. At the position corresponding to the reference numeral 9a in FIG. 9A, that is, at the boundary between the in-groove pit area and the groove area in the optical information recording medium of the above embodiment, the difference signal (radial push-pull signal) ppa shown in the lower part is shown. Almost no disturbance is seen. On the other hand, at the position corresponding to the reference numeral 9b in FIG. 9B, that is, at the boundary between the in-groove pit area and the groove area in the conventional optical information recording medium having in-groove pits, the difference signal (radial) It was confirmed that the disturbance of the push-pull signal) ppb was large. As described above, in the DVD-R and the DVD-RW, tracking is performed by using the radial push-pull signal. At the boundary between the in-groove pit area and the groove area, the balance of the amplitude of the radial push-pull signal is lost. That is, a deviation of the center of the amplitude tends to cause a tracking error.

  Further, in the optical information recording medium manufactured in the above embodiment, the amount of change between the radial push-pull signal in the groove portion and the radial push-pull signal in the in-groove pit portion is the amplitude of the radial push-pull signal in a normal state. If it is 100%, it will be 36%. Although not particularly defined in the DVD-R standard, the DVD-RW standard specifies that the amount of fluctuation between the radial push-pull signal in the groove portion and the radial push-pull signal in the pre-pit portion is 20% or more. Therefore, the optical information recording medium of the above embodiment sufficiently satisfies this standard, and does not cause tracking loss (tracking error). On the other hand, in a conventional optical information recording medium having in-groove pits, the above fluctuation amount is about 18 to 20%. Therefore, the conventional optical information recording medium having in-groove pits has a DVD-RW standard lower limit or lower than the lower limit, and is likely to cause tracking error (tracking error).

  In the optical information recording medium of the above embodiment, polycarbonate is used as the substrate, but polymethyl methacrylate or amorphous polyolefin may be used. Further, in the optical information recording medium of the above embodiment, each layer was formed in the order of the recording layer and the reflective layer on the substrate, but first, the reflective layer was formed on the pattern forming surface on the substrate, and then on the reflective layer. Each layer may be formed by forming a recording layer. Even when an optical information recording medium is manufactured with such a layer configuration, the same effects as in the above embodiment can be obtained.

Another embodiment of the optical information recording medium according to the present invention will be described with reference to FIG. The optical information recording medium in this example was configured in the same manner as in Example 1 except that tellurium (Te) was used as a metal material for the recording layer. In this recording layer, information is recorded and reproduced by AgInSbTe. As shown in FIG. 10, a metal material containing Te was formed as a recording layer 2 'on the surface of the substrate 1' on which lands, grooves, and in-groove pits were formed to a thickness of 15 nm by a sputtering method. . Further, in the same manner as in Example 1, an Ag alloy was formed with a thickness of 160 nm on the recording layer 2 'by using a sputtering method. Thus, a reflective layer 3 ′ was obtained. Recording layer 2 'as a material for, by using a AgInSbTe, substrate 1' thickness tr ₂ of the recording layer 2 ', which is laminated on the pattern forming surface of the is substantially constant regardless of the location. The thickness tr ₃ 'of the reflective layer 3 stacked on the' recording layer 2 is also substantially constant regardless of the location. Therefore, it is easy to grasp the thickness of the recording layer and the reflective layer in each area of the medium, and it is possible to control the thickness of the layer to be laminated based on the information. Thereby, a more stable layer can be formed on the optical information recording medium.

  Another embodiment of the present invention will be described with reference to FIGS. This embodiment is the same as the embodiment except that a groove wider than the groove in the groove region (hereinafter referred to as a boundary groove) is formed between the groove region and the boundary pit region of the substrate used for the optical information recording medium for one track. 1 was constructed in the same manner. Hereinafter, a method of manufacturing the master, the stamper, and the optical information recording medium used for manufacturing the substrate will be described.

  In the present embodiment, the exposure intensity of the laser beam applied to the glass master is changed using the optical modulator while moving the laser light on the glass master, as in the first embodiment. In the present embodiment, as shown in FIG. 11, the exposure intensity of the laser beam was changed in four stages of level 1, level 2, level 3, and level 4 in ascending order. In this embodiment, the ratio of each level is set so that when level 4 is 100%, level 3 is 90%, level 2 is 60%, and level 1 is 55%. As shown in FIG. 11, the exposure intensity in the first and second groove forming regions was set to level 1. In the in-groove pit formation region, the exposure intensity of the in-groove pit formation portion was set to level 4, and the exposure intensity of the other groove portions was set to level 1. The exposure intensity of the groove forming portion of the boundary groove forming region was set to level 2. The exposure intensity of the in-groove pit formation portion in the boundary pit formation region was set to level 3, and the exposure intensity of the other groove portions was set to level 1. In the optical information recording medium of the present embodiment, by providing the boundary groove, even if the pit formed in the boundary pit is formed larger than that in the first embodiment, the groove width from the boundary groove area to the boundary pit area is increased. Of the radial push-pull signal is less likely to occur. As a result, a sufficient degree of modulation can be obtained even in the in-groove pit formed in the boundary pit. Therefore, the pattern of the in-groove pit formed in the boundary pit is not limited to a random pattern such as a dummy, but may be a recording signal pattern of user information. As a result, a pattern corresponding to the above-mentioned in-groove pits is also formed in the in-groove pit forming portion in the boundary pit forming area of the master.

  Next, the glass master to which the photoresist was exposed was developed in the same manner as in Example 1, and the glass master was etched using an RIE apparatus or the like according to the remaining photoresist pattern. Thus, a glass master having a desired concavo-convex pattern formed on the surface was obtained. In this example, the groove forming portion and the boundary groove forming portion were etched to a depth of 170 nm from the surface of the glass master, and the in-groove pit forming portion and the boundary pit forming portion were etched to a depth of 260 nm from the surface of the glass master. Further, the boundary groove forming portion was formed wider than the groove forming portion.

  Further, in the present embodiment, similarly to the first embodiment, when the exposure intensity is changed during the exposure, a period in which the exposure intensity of the laser light is temporarily set to the 0 level every time the exposure intensity is switched is provided. Further, in the present embodiment, the master exposure was performed while controlling the exposure intensity of each in-groove pit forming portion having a predetermined pit length in the in-groove pit forming area as follows. As shown in FIG. 11, exposure is performed at level 4 for 1T to 1.5T (T: clock cycle) from the start of exposure, and then the exposure intensity is increased to 70% of level 4 for a predetermined period (level A). And exposed. Further, during the period from 1T to 1.5T until the end of the in-groove pit formation portion, the exposure intensity was returned to level 4 again, and exposure was performed. This prevents the width of each in-groove pit formation portion in the radial direction of the master from expanding near the middle of the in-groove pit formation portion in the track direction. The exposure intensity of the in-groove pit formation portion in the boundary pit formation region may be similarly controlled.

  A stamper was manufactured using the master thus obtained, and a substrate was manufactured using an injection molding method in the same manner as in Example 1. Next, as shown in FIG. 12B, a recording layer 2 and a reflective layer 3 were formed in the same manner as in Example 1. An optical information recording medium was obtained by attaching a dummy substrate to the obtained substrate via a photocurable resin.

  In the optical information recording medium thus obtained, the in-groove pit portion of the in-groove pit region 73, the boundary pit portion of the boundary pit region 74, the groove portion of the boundary groove region 76, and the The maximum depth of the groove portion was measured using AFM manufactured by Digital Instruments. As shown in FIG. 12B, the maximum depth dg of the groove portion was 170 nm. The maximum depth dgb of the boundary groove portion was 170 nm. The maximum depth dpb of the boundary pit portion was 260 nm. The maximum depth dp of the in-groove pit portion was 260 nm. Note that the maximum depth dg of the groove portion and the maximum depth dp of the in-groove pit portion are set to satisfy 1.4 ≦ dp / dg ≦ 1.7 in order to obtain good recording / reproducing signal characteristics such as good signal modulation and jitter. It is desirable to satisfy the following conditions.

  With reference to the surface of the land 80, the half width Wp of the in-groove pit portion of the in-groove pit region 73, the half-width Wpb of the boundary pit portion of the boundary pit region 74, the half-width Wgb of the groove portion of the boundary groove region 76, The half-value width Wg in the groove portion of the groove region 75 was measured using an AFM manufactured by Digital Instruments. The half width Wg was 320 nm, the half width Wgb was 330 nm, the half width Wpb was 360 nm, and the half width Wp was 400 nm. From this, it is understood that the relationship of Wg ≦ Wgb ≦ Wpb <Wp holds. Further, the ratio Wp / Wpb of the half-value width Wp to the half-value width Wpb = 1.11, which satisfies the condition of 1.05 ≦ Wp / Wpb ≦ 1.15. Furthermore, the ratio Wgb / Wg of the half-value width Wgb to the half-value width Wg is 1.03, and it can be seen that the condition of 1.03 ≦ Wgb / Wg ≦ 1.15 is satisfied.

  Further, in the optical information recording medium obtained in this embodiment, as shown in FIG. 12A, as a result of the exposure according to the above-described exposure schedule, the track direction of the in-groove pits 73a in the in-groove pit area 73 is changed. Near the middle portion, the width of the substrate in the radial direction is suppressed from expanding. Thereby, a land surface having a sufficient area can be ensured even in the land portion 77 adjacent to the in-groove pit. Therefore, a stable radial push-pull signal can be obtained from this optical information recording medium.

  Further, in order to adjust the effect of suppressing the spread of the width of the in-groove pit 73a, the width of the in-groove pit having the shortest channel bit length 3T in the substrate radial direction and the channel bit length longer than that in the in-groove pit region 73 are adjusted. The width of each of the in-groove pits in the radial direction of the substrate was measured using a scanning probe microscope manufactured by Digital Instruments. The maximum width of the in-groove pit having the shortest channel bit length 3T was 0.34 μm. The maximum width of the in-groove pit having a channel bit length of 11T was 0.38 μm. Further, the maximum width of the in-groove pit having a channel bit length of 14T was 0.4 μm. From experiments by the present inventors, the ratio of the maximum width of an in-groove pit having a channel bit length longer than the shortest channel bit length 3T to the maximum width of an in-groove pit having the shortest channel bit length 3T is in the range of 112 to 118%. It can be seen that in the in-groove pits longer than the shortest channel bit length, the width expansion in the substrate radial direction is suppressed.

  Further, in the same manner as in Example 1, the in-groove pit portion of the in-groove pit region 73, the boundary pit portion of the boundary pit region 74, the boundary groove region 76, and the groove portions of the groove region 75 of the obtained optical information recording medium are obtained. The depth of the recording layer depression was measured using AFM manufactured by Digital Instruments. As shown in FIG. 12B, the recording layer depression depth Tp in the in-groove pit region 73 was 170 nm. The recording layer depression depth Tpb in the boundary pit region 74 was 135 nm. The recording layer recess depth Tgb of the boundary groove area 76 was 110 nm. The recording layer depression depth Tg of the groove region 75 was 100 nm. The recording layer depression depth Tp and the recording layer depression depth Tg are 1.6 ≦ Tp / Tg ≦ in order to obtain good recording / reproducing signal characteristics such as good signal modulation and jitter as in the first embodiment. It is desirable to satisfy the condition of 2.0.

  The recording layer depression depth Tpb of the boundary pit area 74, the recording layer depression depth Tp of the in-groove pit area 73, the recording layer depression depth Tgb of the boundary groove area 76, and the recording layer depression depth of the groove area 75. The relationship with the height Tg is Tg <Tgb <Tpb <Tp from the relationship of the groove half width in each of the above regions.

  The recorded information in the in-groove pit area was reproduced from the optical information recording medium obtained in the above example by using an optical pickup having a laser beam having a wavelength of 650 nm and a lens having a numerical aperture of 0.6. The detection and reproduction of the signal could be performed stably. At this time, the signal modulation degree of the reproduced signal was 61% and the jitter was 7.2%, and good results were obtained in each case.

  Still another embodiment of the present invention will be described with reference to FIGS. In this embodiment, the configuration is the same as that of the third embodiment except that the boundary pit area used for the optical information recording medium is not provided and only the boundary groove area is formed between the groove area and the in-groove pit formation area. Hereinafter, a method for manufacturing the master, stamper, and optical information recording medium used for manufacturing the substrate will be described.

  In the present embodiment, as shown in FIG. 13, the master disc exposure was performed using the exposure intensity of the laser beam at three levels of level 1, level 2, and level 4 of the exposure intensity used in the third embodiment. . As in the third embodiment, the ratio of each level in this embodiment is set so that when level 4 is 100%, level 2 is 60% and level 1 is 55%. As shown in FIG. 13, the exposure intensity in the first and second groove forming regions was set to level 1. In the in-groove pit formation region, the exposure intensity of the in-groove pit formation portion was set to level 4, and the exposure intensity of the other groove portions was set to level 1. The exposure intensity of the groove forming portion of the boundary groove forming region was set to level 2.

  Next, the glass master to which the photoresist was exposed was developed in the same manner as in Example 1, and the glass master was etched using an RIE apparatus or the like according to the remaining photoresist pattern. Thus, a glass master having a desired concavo-convex pattern formed on the surface was obtained. In this example, the groove forming portion and the boundary groove forming portion were etched to a depth of 170 nm from the surface of the glass master, and the in-groove pit forming portion was etched to a depth of 260 nm from the surface of the glass master. Further, the boundary groove forming portion was formed wider than the groove forming portion.

  Further, in the present embodiment, similarly to the third embodiment, when the exposure intensity is changed during the exposure, a period in which the exposure intensity of the laser beam is temporarily set to the 0 level every time the exposure intensity is switched is provided. In addition, as shown in FIG. 13, in the in-groove pit formation region, the master exposure was performed while controlling the exposure intensity of each in-groove pit formation portion having a predetermined pit length in the same manner as in Example 3.

  Using the master thus obtained, a substrate was produced in the same manner as in Example 3 by using an injection molding method. Next, as shown in FIG. 14B, a recording layer 2 and a reflective layer 3 were formed in the same manner as in Example 3. An optical information recording medium was obtained by attaching a dummy substrate to the obtained substrate via a photocurable resin.

  For the optical information recording medium thus obtained, the maximum depth of the in-groove pit portion of the in-groove pit region 73, the groove portion of the boundary groove region 76, and the groove portion of the groove region 75 is determined in the same manner as in the third embodiment. It measured using AFM made by Instruments. As shown in FIG. 14B, the maximum depth dg of the groove portion was 170 nm. The maximum depth dgb of the boundary groove portion was 170 nm. The maximum depth dp of the in-groove pit portion was 260 nm. Note that the maximum depth dg of the groove portion and the maximum depth dp of the in-groove pit portion are set to satisfy 1.4 ≦ dp / dg ≦ 1.7 in order to obtain good recording / reproducing signal characteristics such as good signal modulation and jitter. It is desirable to satisfy the following conditions.

  Further, with respect to the surface of the land 80, the half width Wp of the in-groove pit portion of the in-groove pit region 73, the half-width Wgb of the groove portion of the boundary groove region 76, and the half-width Wg of the groove portion of the groove region 75 are respectively The measurement was performed using an AFM manufactured by Digital Instruments. The half width Wg was 320 nm, the half width Wgb was 350 nm, and the half width Wp was 400 nm. From this, it is understood that the relationship of Wg <Wgb ≦ Wp holds. Furthermore, the ratio Wgb / Wg of the half-value width Wgb to the half-value width Wg = 1.09, which satisfies the condition of 1.05 ≦ Wgb / Wg ≦ 1.15.

  Further, as shown in FIG. 14A, as a result of exposure according to the above-described exposure schedule, the width of the in-groove pit 73a in the radial direction of the substrate is suppressed near the middle of the in-groove pit 73a in the track direction. ing. As a result, a land surface having a sufficient area can be ensured even in the land portion 77 'adjacent to the in-groove pit. Therefore, a stable radial push-pull signal can be obtained from this optical information recording medium.

  Further, in order to adjust the effect of suppressing the spread of the width of the in-groove pit 73a, the width of the in-groove pit having the shortest channel bit length 3T in the substrate radial direction and the channel bit length longer than that in the in-groove pit region 73 are adjusted. The width of each of the in-groove pits in the radial direction of the substrate was measured using a scanning probe microscope manufactured by Digital Instruments. The maximum width of the in-groove pit having the shortest channel bit length 3T was 0.34 μm. The maximum width of the in-groove pit having a channel bit length of 11T was 0.38 μm. Further, the maximum width of the in-groove pit having a channel bit length of 14T was 0.4 μm. From experiments by the present inventors, the ratio of the maximum width of the in-groove pit having a channel bit length longer than the shortest channel bit length 3T to the maximum width of the in-groove pit having the shortest channel bit length 3T is 100% to 118%. Within the range, preferably within the range of 112 to 118%, it can be seen that in the in-groove pits longer than the shortest channel bit length, the width expansion in the substrate radial direction is suppressed.

  In the same manner as in Example 3, the depth of the recording layer depression of the in-groove pit portion of the in-groove pit region 73, the boundary groove region 76, and the groove portion of the groove region 75 of the obtained optical information recording medium was determined by digital instruments. It measured using AFM made by company. As shown in FIG. 14B, the recording layer depression depth Tp in the in-groove pit region 73 was 170 nm. The recording layer depression depth Tgb of the boundary groove area 76 was 120 nm. The recording layer depression depth Tg of the groove region 75 was 100 nm. The recording layer depression depth Tp and the recording layer depression depth Tg are 1.6 ≦ Tp / Tg ≦ in order to obtain good recording / reproducing signal characteristics such as good signal modulation and jitter as in the first embodiment. It is desirable to satisfy the condition of 2.0.

  The relationship between the recording layer depression depth Tp of the in-groove pit area 73, the recording layer depression depth Tgb of the boundary groove area 76, and the recording layer depression depth Tg of the groove area 75 is represented by the following equation. From the relation of the value width, Tg <Tgb <Tp.

  The recorded information in the in-groove pit area was reproduced from the optical information recording medium obtained in the above example by using an optical pickup having a laser beam having a wavelength of 650 nm and a lens having a numerical aperture of 0.6. The detection and reproduction of the signal could be performed stably. At this time, the signal modulation degree of the reproduced signal was 61% and the jitter was 7.2%, and good results were obtained in each case.

  At the time of master exposure in Examples 3 and 4, the exposure intensity of the in-groove pit formation portion having a predetermined pit length in the in-groove pit formation region is first set to the first exposure intensity, and then lower than the first exposure intensity. Although the second exposure intensity is controlled so as to be changed to the first exposure intensity, the same exposure intensity control may be performed during master exposure in the first and second embodiments.

  A fifth embodiment of the present invention will be described with reference to FIGS. In the optical information recording medium of the present embodiment, as shown in FIG. 16, land pre-pits LPP are formed at predetermined intervals in the track direction on the lands of the substrate 1 and the grooves excluding the boundary groove area 176 are formed on the substrate. And the land prepits LPP are formed continuously and deeply from the inner circumference to the outer circumference of the substrate. Other than that, the configuration was the same as that of the third embodiment. The land pre-pits LPP are used for recording the position information of the medium and the like on the optical information recording medium in advance. Hereinafter, a method for manufacturing the master, stamper, and optical information recording medium used for manufacturing the substrate will be described.

  FIG. 17 shows a change in exposure intensity of laser light in the vicinity of the in-groove pit formation region of the glass master. FIG. 18 shows a change in the exposure intensity of the laser beam on the entire glass master. In the present embodiment, as shown in FIG. 17, the exposure intensity of the laser beam uses the four levels of the exposure intensity levels 1, 2, 3, and 4 used in the third embodiment, and FIG. As shown, the master exposure was performed while continuously changing the exposure intensity at level 1, ie, the groove level, from the inner circumference to the outer circumference of the glass master. In this embodiment, the ratio of each level is set such that when level 4 is 100%, level 2 is 60% and level 3 is 90%. As shown in FIG. 18, the level 1 is 55% at the exposure start position of the glass master (a position at a radius of 19.0 mm from the center of the glass master), and the exposure end position is a position at a radius of 58.9 mm from the center of the glass master. Then, it was continuously changed to be 60%. In this way, by changing the exposure intensity at the groove level so as to increase continuously, the width of the pattern corresponding to the groove is continuously increased from the inside to the outside of the glass master so that the pattern is formed on the glass master. A pattern corresponding to the groove can be formed.

  Further, as shown in FIG. 17, the exposure intensity in the first and second groove forming regions was set to level 1 respectively. In the in-groove pit formation region, the exposure intensity of the in-groove pit formation portion was set to level 4, and the exposure intensity of the other groove portions was set to level 1. The exposure intensity of the groove forming portion of the boundary groove forming region was set to level 2. The exposure intensity of the in-groove pit formation portion in the boundary pit formation region was set to level 3, and the exposure intensity of the other groove portions was set to level 1. In this embodiment, similarly to the third embodiment, when the exposure intensity is changed during the exposure, a period in which the exposure intensity of the laser beam is temporarily set to the 0 level every time the exposure intensity is changed is provided. In the in-groove pit formation region, master exposure was performed by controlling the exposure intensity of each in-groove pit formation portion having a predetermined pit length to be temporarily reduced (to level A). In this example, the ratio of the exposure intensity level A was set to 75%.

  Although not shown, when exposing a portion corresponding to a land prepit formed on a land of the substrate (hereinafter, referred to as a land prepit formation portion), the depth of the land prepit is adjacent to the groove. Laser light in the same manner as the above-described exposure intensity control method so that the groove width becomes substantially the same as the depth of the substrate and the groove width continuously increases from the inner periphery to the outer periphery of the substrate. The exposure intensity was adjusted. Note that the land pre-pit formation portion was exposed using laser light different from the laser light used for exposure of the groove formation portion, the in-groove pit formation portion, and the like.

  Next, the glass master to which the photoresist was exposed was developed in the same manner as in Example 3, and the glass master was etched using an RIE apparatus or an ashing apparatus in accordance with the remaining photoresist pattern. Thus, a glass master (not shown) having a desired concavo-convex pattern formed on the surface was obtained. In this embodiment, in order to form a groove having a uniform depth in the track direction and continuously increasing from the inner periphery to the outer periphery of the glass master, the RIE apparatus is controlled as follows. did.

[Control Method of RIE Apparatus]
FIG. 19 shows a schematic view of the RIE apparatus. The RIE apparatus 200 mainly includes a hermetically sealable chamber 201, an anode 203, a cathode 204, an RF power supply 205, an insulator section 207, exhaust pipes 209 and 210, a gas supply pipe 211, and cooling water supply pipes 213 and 214. . The anode 203 is installed above the chamber 201 together with the gas supply pipe 211 and the cooling water supply pipe 213. The cathode 204 is installed below the inside of the chamber 201 via an insulator portion 207, and a master to be etched is placed on the upper surface of the cathode 204. The exhaust pipe 209 is provided on a lower surface in the chamber 201 so as to communicate with the inside of the chamber 201. The exhaust pipe 210 is provided on the side wall of the chamber 201 so as to communicate with the inside of the chamber 201, and the pressure in the chamber 201 can be adjusted by a gate valve 215 provided in the exhaust pipe 210.

First, a predetermined amount of process gas (C ₂ F ₆ ) is supplied into the chamber 201 via a gas supply pipe 211 from a gas supply unit (not shown) provided on the anode 203 side of the RIE apparatus 200. At this time, excess process gas is exhausted through the exhaust pipe 209 so that the pressure in the chamber 201 is always constant. By applying power to the cathode 204 by the RF power supply 205 in a state where the chamber 201 is filled with the process gas, the inside of the chamber 201 becomes a plasma state, and the glass master 50 on which the patterned photoresist layer is formed is etched. Is done.

  Generally, in RIE, it is known that the faster the gas flow in the chamber, the higher the etching rate. In addition, the inventors of the present invention have studied various conditions of gas flow rate, pressure and applied power in RIE, and as a result, in order to cause a difference in the depth of grooves formed inside and outside of the master, respectively. In particular, it has been found that the pressure in the chamber is significantly related. As the pressure in the chamber is set higher, the flow rate of the gas flowing in the chamber of the RIE apparatus becomes different between inside and outside. As a result, the flow rate of the gas decreases as the position is closer to the center in the chamber, that is, the gas flow is slower, and the flow rate of the gas increases as the position is closer to the inner wall of the chamber, that is, the flow of the gas increases. Therefore, a groove is formed such that the etching rate increases as the position is closer to the outside of the glass master, and the groove continuously becomes deeper from the inside to the outside of the glass master.

  In this embodiment, the gas flow rate and the applied power of the RIE device are fixed, and only the pressure is set to the conventional pressure (condition 1) as a reference, twice the pressure (condition 2), and four times the pressure (condition). 3) Etching the glass master with various changes so that the pressure becomes 8 times the pressure (Condition 4) and 16 times the pressure (Condition 5), and the difference between the inside and outside of the groove depth formed in the glass master. Were compared. Table 1 shows the results. Table 1 also shows the stability of the plasma under each condition. The stability of the plasma is obtained by examining whether or not the plasma flickers or discharges during the etching. In the table, “〇” indicates a level that does not cause any problem, “x” indicates a level that lacks discharge stability and is considered difficult to process the master with reproducibility, and “△” indicates an intermediate level. Each is shown. From the results in Table 1, it can be seen that as the pressure in the chamber is set higher, the difference between the groove depths on the inside and outside of the master increases, but the stability of the plasma in the chamber also deteriorates. In order to obtain a certain amount of difference in groove depth while maintaining the stability of the plasma, it is preferable to set the pressure in the chamber to the pressure of the condition 3, that is, four times the pressure in the related art. Thus, a difference between the inside and outside of the groove depth of about 10 nm can be obtained.

  In this example, the boundary groove forming portion was etched to a depth of 170 nm from the surface of the glass master, and the in-groove pit forming portion and the boundary pit forming portion were etched to a depth of 250 nm from the surface of the glass master. Further, the groove forming portion was etched to a depth of 160 nm from the surface of the glass master at the inner periphery (radius 23.0 mm) of the glass master and to a depth of 170 nm at the outer periphery (radius 58.7 mm). Further, the land pre-pit formation portion has the same depth as the groove depth of the groove formation portion adjacent to each land pre-pit formation portion. Etching was performed to a depth of 170 nm from the surface of the glass master.

  At this time, the groove width at half the depth of the groove forming portion was 310 nm at the inner periphery (radius 23.0 mm) of the glass master and 330 nm at the outer periphery (radius 58.7 mm). The groove width at half the depth of the boundary groove forming portion is 330 mm, which is wider than the width of the adjacent groove forming portion. Further, the width of the land prepit formation portion was 170 nm at the inner periphery of the glass master and 200 nm at the outer periphery. At this time, the length in the track direction (pit length) of the land prepit formation portion in the inner peripheral portion was 170 nm, and the length in the track direction (pit length) of the land prepit formation portion in the outer peripheral portion was 200 nm.

  Using the master thus obtained, a substrate was produced in the same manner as in Example 3 by using an injection molding method. Next, in the same manner as in Example 3, a recording layer 2 and a reflective layer 3 were formed as shown in FIG. An optical information recording medium was obtained by attaching a dummy substrate to the obtained substrate 1 via a photocurable resin.

  In this optical information recording medium, the in-groove pit portion of the in-groove pit region, the boundary pit portion of the boundary pit region, the maximum depth of the groove portion of the boundary groove region from the substrate surface (land surface), the inner peripheral portion of the groove region (Radius of 23.0 mm) and the outermost portion (radius of 55.0 mm), the maximum depth from the substrate surface, and the inner peripheral portion (radius of 23.0 mm) and the outer peripheral portion (radius of 55.0 mm). The maximum depth of the pit from the substrate surface was measured using AFM manufactured by Digital Instruments. The maximum depth dgi of the groove portion in the inner peripheral portion was 155 nm. The maximum depth dgo of the outer peripheral groove portion was 165 nm. The ratio of the maximum depth dgi to the maximum depth dgo is dgo / dgi = 1.06, and it can be seen that the condition of 1.00 <dgo / dgi ≦ 1.10. The maximum depth dgb of the boundary groove was 155 nm. The maximum depth dpb of the boundary pit portion was 245 nm. The maximum depth dp of the in-groove pit portion was 245 nm. Note that the maximum depth dg of the groove portion (dgi ≦ dg ≦ dgo) and the maximum depth dp of the in-groove pit portion are set to satisfy 1.4 ≦ to obtain a good signal modulation degree and recording / reproducing signal characteristics such as jitter. It is desirable to satisfy the condition of dp / dg ≦ 1.7. The maximum depth dlpi of the land prepits on the inner periphery was 155 nm, and the maximum depth dlpo of the land prepits on the outer periphery was 165 nm. The groove depth was almost the same as the groove depth of the adjacent groove portion. It can be seen that in both the groove portion and the land prepit, the groove is formed deeper in the outer peripheral portion than in the inner peripheral portion of the medium.

  Further, based on the surface of the land, the half width Wp of the in-groove pit portion of the in-groove pit region, the half width Wpb of the boundary pit portion of the boundary pit region, the half width Wgb of the groove portion of the boundary groove region, and the The half widths Wgi and Wgo of the groove portions at the peripheral portion and the outer peripheral portion, and the widths Wlpi and Wlpo of the bottom portions of the land prepits at the inner peripheral portion (radius of 23.0 mm) and the outer peripheral portion (radius of 55.0 mm) are respectively referred to as digital instruments. It measured using AFM made by company. The half width Wgi was 325 nm, the half width Wgo was 345 nm, the half width Wgb was 345 nm, the half width Wpb was 350 nm, and the half width Wp was 400 nm. From this, it is understood that the relationship of Wgi <Wgo ≦ Wgb ≦ Wpb <Wp holds. Further, the ratio Wp / Wpb of the half-value width Wp to the half-value width Wpb = 1.14, which satisfies the condition of 1.05 ≦ Wp / Wpb ≦ 1.15. Further, the ratio Wgo / Wgi of the half-value width Wgi to the half-value width Wgo is 1.06, and it can be seen that the condition of 1.03 ≦ Wgo / Wgi ≦ 1.10. Further, the widths Wlpi and Wlpo at the bottom are 180 nm and 200 nm, respectively, and it can be seen that the width of the land prepit is formed wider at the outer periphery than at the inner periphery of the medium.

  Further, in the optical information recording medium obtained in this embodiment, as a result of exposure according to the above-described exposure schedule, as shown in FIG. 16A, the middle of the in-groove pit 173a in the in-groove pit area 173 in the track direction is obtained. In the vicinity of the portion, the spread of the width in the substrate radial direction is suppressed. As a result, a land surface having a sufficient area is secured on the surface of the land portion 177 adjacent to the in-groove pit. Thus, land pre-pits LPP having a stable shape can be formed on the surface of the land 177. Therefore, a stable radial push-pull signal can be obtained, and the data recorded in the land prepit can be reproduced in a stable state.

  Further, the depth of the recording layer depression in the groove portions of the in-groove pit portion 173a of the in-groove pit region 173, the boundary pit portion 174a of the boundary pit region 174, the boundary groove region 176 and the groove region 175 of the obtained optical information recording medium, In addition, the depth of the recording layer depression of the land prepit was measured using AFM manufactured by Digital Instruments. As shown in FIG. 16B, the recording layer depression depth Tp in the in-groove pit region 173 was 170 nm. The recording layer depression depth Tpb in the boundary pit region 174 was 135 nm. The recording layer depression depth Tgb of the boundary groove region 176 was 115 nm. The recording layer depression depth Tgi at the inner periphery (radius 23.0 mm) of the groove region 175 and the recording layer depression depth Tgo at the outer periphery (radius 55.0 mm) were both 100 nm. Note that the recording layer depression depth Tp and the recording layer depression depth Tg (= Tgi = Tgo) are set to satisfy 1.6 ≦ Tp / Tg ≦ in order to obtain good recording / reproducing signal characteristics such as good signal modulation and jitter. It is desirable to satisfy the condition of 2.0. Further, the recording layer depression depth Tlpi at the inner periphery (radius 23.0 mm) and the recording layer depression depth Tlpo at the outer periphery (radius 55.0 mm) of the land prepit LPP were both 100 nm.

  Further, the recording layer depression depth Tpb of the boundary pit portion 174a, the recording layer depression depth Tp of the in-groove pit portion 173a, the recording layer depression depth Tgb of the boundary groove region 176, and the inner peripheral portion of the groove region 175. The relationship between the recording layer depression depth Tgi and the recording layer depression depth Tgo in the outer peripheral portion is obtained from the relationship between the half width of the groove in each region and the difference between the inner and outer peripheral portions of the recording layer film thickness formed by spin coating. Tgo <Tgb <Tpb <Tp.

  The optical information recording medium obtained in this example was used to reproduce a recording signal in an in-groove pit area by using an optical pickup having a laser beam having a wavelength of 650 nm and a lens having a numerical aperture of 0.6. Signal detection and reproduction can be performed stably. At this time, the signal modulation degree of the reproduced signal changes to about 64 to 65%, and the jitter changes to about 7.8 to 7.5%. Good results could be obtained. In addition, the variation in the reflectivity between the inner and outer circumferences in the recording / reproducing area of the medium was less than 2%, and the variation in the push-pull signal and the variation in the modulation factor of the recording / reproducing signal due to the above-described variation in the reflectivity could be suppressed.

Comparative Example 2
Hereinafter, an optical information recording medium (hereinafter, referred to as medium A) of the present embodiment and an optical information recording medium (hereinafter, referred to as medium A) in which only the groove width of the groove is continuously increased from the inner circumference to the outer circumference of the optical information recording medium. Table 2 shows the results of comparing the characteristics of an optical information recording medium (hereinafter, referred to as medium C) formed so that the groove depth and groove width are uniform over the entire medium. Shown in As is clear from Table 2, the difference between the inner and outer circumferences (the amount of change between the inner and outer circumferences) of the medium A is smaller in any of the characteristics of the optical information recording medium than the media B and C, ie, the radial position of the medium It can be seen that substantially uniform characteristics can be obtained regardless of the characteristics.

  In the present embodiment, the optical information recording medium in which both the boundary pits and the boundary grooves are formed has been described. However, the method for manufacturing the optical information recording medium in the present embodiment is based on the optical information recording medium in which only the boundary pits are formed or only the boundary grooves. It is also possible to apply to an optical information recording medium in which is formed. As a result, an optical information recording medium having uniform characteristics inside and outside the medium can be obtained as in the present embodiment.

  In the optical information recording medium of the present invention, by providing the boundary pit area between the in-groove pit area and the groove area, it is possible to suppress a tracking error generated between the in-groove pit area and the groove area. . The method for manufacturing an optical information recording medium of the present invention is useful for manufacturing the optical information recording medium of the present invention.

  By providing a wide groove (boundary groove) between the groove formation region and the boundary pit formation region, it is possible to obtain good tracking characteristics while maintaining the modulation degree of the boundary pit in a good state. Even when only the boundary groove is provided instead of the boundary pit formation region, stable servo control can be performed.

  In the optical information recording medium according to the present invention in which the in-groove pit is formed and the recording layer made of the organic dye material is formed, the groove and the land pre-pit extend from the inside (inner circumference) to the outer (outer circumference) of the medium. Are formed to be continuously deep and wide. Thereby, the interface height between the recording layer and the reflective layer formed in the groove portion or the land pre-pit portion becomes constant without any difference between inside and outside. As a result, a stable push-pull signal can be obtained from the inner circumference to the outer circumference of the medium, and the data recorded in the land pre-pits can be reproduced stably.

(A) is a schematic top view showing a part of a conventional optical information recording medium having in-groove pits, and (b) is a cross-sectional view taken along line AA of (a). FIG. 2 is a view for explaining a method of manufacturing a glass master in Example 1. FIG. 3 is a diagram illustrating a change over time in the exposure intensity of a laser beam applied to a glass master in Example 1. (A) is a schematic top view showing a part of the glass master immediately after photoresist exposure and development in Example 1, and (b) is a cross-sectional view taken along line A'-A 'of (a). FIG. 2 is a view for explaining a method of manufacturing a glass master in Example 1. FIG. 2 is a schematic perspective view of a pattern formation surface of a substrate obtained in Example 1. FIG. 2 is a schematic view of a substrate obtained in Example 1. (A) is a schematic top view near the boundary pit area of the optical information recording medium in Example 1, and (b) is a view showing a cross section taken along line CC of (a). FIG. 4 is a diagram showing a sum signal and a difference signal (radial push-pull signal) near a boundary between an in-groove pit area and a groove area, and FIG. It is a figure showing a signal, and (b) is a figure showing those signals of a conventional information recording medium having an in-groove pit. FIG. 9 is a schematic cross-sectional view near a boundary between an in-groove pit area and a groove area of an optical information recording medium according to a second embodiment. FIG. 13 is a diagram showing a time change of an exposure intensity of a laser beam applied to a glass master in Example 3. (A) is a schematic top view near the boundary pit region of the optical information recording medium in Example 3, and (b) is a diagram showing a cross section taken along line DD of (a). FIG. 14 is a diagram illustrating a change over time in the exposure intensity of a laser beam applied to a glass master in Example 4. (A) is a schematic top view near the boundary pit region of the optical information recording medium in Example 4, and (b) is a diagram showing a cross section taken along line EE of (a). FIG. 4 is a diagram illustrating a cause of a tracking error occurring at a boundary between a groove forming region and an in-groove pit forming region. (A) is a schematic top view near the boundary pit region of the optical information recording medium in Example 5, and (b) is a diagram showing a cross section taken along line FF of (a). FIG. 13 is a diagram illustrating a temporal change in exposure intensity near an in-groove pit formation region of a laser beam applied to a glass master in Example 5. FIG. 13 is a diagram illustrating a temporal change in the exposure intensity of the entire glass master disk with respect to the laser beam applied to the glass master disk in Example 5. FIG. 13 is a schematic diagram of an RIE apparatus used in Example 5.

Explanation of reference numerals

1, 1 ', 101 substrate 2, 2', 102 recording layer 3, 3 ', 103 reflective layer 40 groove forming part 42 boundary pit forming part 44 in groove pit forming part 50 glass master 52 photoresist 71, 75 groove area 73 In-groove pit area 72, 74 Boundary pit area 101a Land surface 105 Groove 107 In-groove pit sa, sb Sum signal ppa, ppb Difference signal (radial push-pull signal)
AX center axis AX center axis

Claims (40)

A substrate on which a plurality of lands and grooves are formed, and an optical information recording medium having a recording layer and a reflective layer containing an organic dye on the substrate,
The groove is a first groove;
A second groove in which pits are formed;
A third groove in which a pit narrower than the pit of the second groove is formed;
A third groove is disposed between the first groove and the second groove;
A groove width such that the first groove, the second groove, and the third groove are continuously deepened from the inside to the outside of the optical information recording medium, and are continuously widened. An optical information recording medium characterized by being formed of: The half value width of the first groove located inside the optical information recording medium is represented by Wgi, the half value width of the first groove located outside the optical information recording medium is represented by Wgo, and the half value width in the pits of the second groove. 2. The optical information recording medium according to claim 1, wherein Wgi <Wgo ≦ Wpb <Wp, wherein Wgi <Wgo ≦ Wpb <Wp when the half-width of the pit of the third groove is represented by Wpb. 3. The optical information recording medium according to claim 2, wherein a ratio Wp / Wpb between the half width Wp and the half width Wpb satisfies 1.05 ≦ Wp / Wpb ≦ 1.15. The depth of the first groove located inside the optical information recording medium from the substrate surface was represented by dgi, and the depth of the first groove located outside the optical information recording medium from the substrate surface was represented by dgo. The light according to any one of claims 1 to 3, wherein a ratio dgo / dgi between the depth dgi and the depth dgo satisfies 1.00 <dgo / dgi ≦ 1.10. Information recording medium. The optical information recording medium according to any one of claims 2 to 4, wherein a ratio Wgo / Wgi of a half value width Wgi and a half value width Wgo satisfies 1.03 ≦ Wgo / Wgi ≦ 1.10. . The depth of the depression of the recording layer from the interface between the recording layer and the reflective layer on the land surface to the interface between the recording layer and the reflective layer in the first groove located inside the optical information recording medium is represented by Tgi. The depth of the depression of the recording layer from the interface between the recording layer and the reflection layer on the land surface to the interface between the recording layer and the reflection layer in the first groove located outside the optical information recording medium is represented by Tgo. The depth of the pit of the recording layer from the interface between the recording layer and the reflective layer in the pit of the second groove from the interface between the recording layer and the reflective layer on the surface is represented by Tp. 2. The depth of the depression of the recording layer from the interface of the recording layer to the interface between the recording layer and the reflection layer in the pit of the third groove is represented by Tpb, and Tgi = Tgo <Tpb <Tp. Any of ~ 5 The optical information recording medium according to claim. The pits formed in the same groove of the groove are composed of a first pit and a second pit having a length in the groove direction longer than the first pit, and a maximum width of the first pit in a substrate radial direction. the expressed as _{W 1,} when the maximum width of the substrate radially in the second pit expressed in _{W 2,} any one of the preceding claims, characterized in that it is _{1 ≦ W 2 / W 1 <} 1.2 The optical information recording medium according to claim 1. The optical information recording medium according to any one of claims 1 to 7, wherein the organic dye material is an azo dye material. It is a manufacturing method of the optical information recording medium according to any one of claims 1 to 8,
By irradiating the photosensitive material formed on the master with an exposure intensity that continuously changes from the inside to the outside of the master, the first groove, the second groove, and the third groove are applied to the photosensitive material. Exposing a pattern corresponding to pits of a second groove and a pit of a third groove to the photosensitive material by exposing a pattern corresponding to the groove of the groove and irradiating the photosensitive material at two different exposure intensities;
Forming a pattern corresponding to the first groove, the pitted second groove, and the pitted third groove by performing development and etching by RIE on the master after the exposure;
Forming a substrate using the master on which the pattern is formed;
Forming a recording layer and a reflective layer on the substrate. The exposure intensity at the time of exposing the pattern corresponding to the pit is first set to the first exposure intensity, then to the second exposure intensity lower than the first exposure intensity, and further to the first exposure intensity. The method for manufacturing an optical information recording medium according to claim 9, wherein: 11. The light according to claim 10, wherein when a clock cycle for reproducing the optical information recording medium is represented by T, the period of exposure at the first exposure intensity is set to 1T to 1.5T, respectively. Manufacturing method of information recording medium. The method of manufacturing an optical information recording medium according to any one of claims 9 to 11, further comprising, when exposing the master, setting the exposure intensity to 0 in addition to the exposure intensity. 13. The method of manufacturing an optical information recording medium according to claim 9, wherein the etching by RIE is performed by changing a flow rate of a gas used for RIE between the inside and outside of the master. A substrate on which a plurality of lands and grooves are formed, and an optical information recording medium having a recording layer and a reflective layer containing an organic dye on the substrate,
The groove is a first groove;
A second groove wider than the first groove;
A third groove in which pits are formed;
A second groove is disposed between the first and third grooves;
The first and third grooves are formed so as to have a groove depth that continuously increases from the inside to the outside of the optical information recording medium and a groove width that continuously increases. An optical information recording medium characterized by the above-mentioned. The half width of the first groove located inside the optical information recording medium is represented by Wgi, the half width of the first groove located outside the optical information recording medium is represented by Wgo, and the half width of the second groove is represented by Wgb. 15. The optical information recording medium according to claim 14, wherein Wgi <Wgo ≦ Wgb ≦ Wp, where Wp represents the half-value width of the pit of the third groove. The depth of the first groove located inside the optical information recording medium from the substrate surface is represented by dgi, and the depth of the first groove located outside the optical information recording medium from the substrate surface is represented by dgo. 16. The optical information recording medium according to claim 14, wherein a ratio dgo / dgi between the depth dgi and the depth dgo satisfies 1.00 <dgo / dgi ≦ 1.10. 17. The optical information recording medium according to claim 15, wherein a ratio Wgo / Wgi between the half width Wgi and the half width Wgo satisfies 1.03 ≦ Wgo / Wgi ≦ 1.10. The depth of the depression of the recording layer from the interface between the recording layer and the reflective layer on the land surface to the interface between the recording layer and the reflective layer in the first groove located inside the optical information recording medium is represented by Tgi. The depth of the depression of the recording layer from the interface between the recording layer and the reflection layer on the land surface to the interface between the recording layer and the reflection layer in the first groove located outside the optical information recording medium is represented by Tgo. The depth of the depression of the recording layer from the interface between the recording layer and the reflective layer in the second groove from the interface between the recording layer and the reflective layer on the surface is represented by Tgb, and the interface between the recording layer and the reflective layer on the land surface is described above. 18. When the depth of the pit of the recording layer from the pit of the third groove to the interface between the recording layer and the reflection layer is represented by Tp, Tgi = Tgo <Tgb <Tp. Any one of The optical information recording medium according. The pits formed in the same groove of the groove are composed of a first pit and a second pit having a length in the groove direction longer than the first pit, and a maximum width of the first pit in a substrate radial direction. the expressed as _{W 1,} when the maximum width of the substrate radially in the second pit expressed in _{W 2,} claim 14 to 18, which is a _{1 ≦ W 2 / W 1 <} 1.2 The optical information recording medium according to claim 1. The optical information recording medium according to any one of claims 14 to 19, wherein the organic dye material is an azo dye material. It is a manufacturing method of the optical information recording medium according to any one of claims 14 to 20,
By irradiating the photosensitive material formed on the master with an exposure intensity that continuously changes from the inside to the outside of the master, the photosensitive material corresponds to the grooves of the first groove and the third groove. Exposing a pattern corresponding to pits of a second groove and a third groove to the photosensitive material by exposing the pattern and irradiating the photosensitive material at two different exposure intensities;
Forming a pattern corresponding to the first groove, the second groove, and the pitted third groove by performing development and etching by RIE on the master after the exposure;
Forming a substrate using the master on which the pattern is formed;
Forming a recording layer and a reflective layer on the substrate. The exposure intensity at the time of exposing the pattern corresponding to the pit is first set to the first exposure intensity, then to the second exposure intensity lower than the first exposure intensity, and further to the first exposure intensity. 22. The method for manufacturing an optical information recording medium according to claim 21, wherein: 23. The light according to claim 22, wherein when a clock cycle for reproducing the optical information recording medium is represented by T, the period of exposure at the first exposure intensity is set to 1T to 1.5T, respectively. Manufacturing method of information recording medium. 24. The method for manufacturing an optical information recording medium according to claim 21, further comprising, when exposing the master, setting the exposure intensity to zero in addition to the exposure intensity. 25. The method for manufacturing an optical information recording medium according to claim 21, wherein the etching by RIE is performed by changing a flow rate of a gas used for RIE between inside and outside of the master. A substrate on which a plurality of lands and grooves are formed, and an optical information recording medium having a recording layer and a reflective layer containing an organic dye on the substrate,
The groove is a first groove;
A second groove wider than the first groove;
A third groove in which pits are formed;
And a fourth groove in which a pit narrower than the pit of the third groove is formed.
The first to fourth grooves are arranged in the order of a first groove, a second groove, a fourth groove, and a third groove,
A groove width such that the first groove, the third groove, and the fourth groove are continuously deepened from the inside to the outside of the optical information recording medium, and are continuously widened. An optical information recording medium characterized by being formed of: The half width of the first groove located inside the optical information recording medium is represented by Wgi, the half width of the first groove located outside the optical information recording medium is represented by Wgo, and the half width of the second groove is represented by Wgb. Where Wgi <Wgo ≦ Wgb ≦ Wpb <Wp when the half width at the pit of the third groove is represented by Wp and the half width at the pit of the fourth groove is represented by Wpb. 27. The optical information recording medium according to 26. 28. The optical information recording medium according to claim 27, wherein a ratio Wp / Wpb between the half width Wp and the half width Wpb satisfies 1.05 ≦ Wp / Wpb ≦ 1.15. The depth of the first groove located inside the optical information recording medium from the substrate surface was represented by dgi, and the depth of the first groove located outside the optical information recording medium from the substrate surface was represented by dgo. The light according to any one of claims 26 to 28, wherein a ratio dgo / dgi between the depth dgi and the depth dgo satisfies 1.00 <dgo / dgi ≦ 1.10. Information recording medium. The optical information recording medium according to any one of claims 27 to 29, wherein a ratio Wgo / Wgi of a half value width Wgi and a half value width Wgo satisfies 1.03 ≦ Wgo / Wgi ≦ 1.10. . The depth of the depression of the recording layer from the interface between the recording layer and the reflective layer on the land surface to the interface between the recording layer and the reflective layer in the first groove located inside the optical information recording medium is represented by Tgi. The depth of the depression of the recording layer from the interface between the recording layer and the reflection layer on the land surface to the interface between the recording layer and the reflection layer in the first groove located outside the optical information recording medium is represented by Tgo. The depth of the depression of the recording layer from the interface between the recording layer and the reflective layer in the second groove from the interface between the recording layer and the reflective layer on the surface is represented by Tgb, and the interface between the recording layer and the reflective layer on the land surface is described above. From the interface between the recording layer and the reflection layer on the land surface from the interface between the recording layer and the reflection layer on the land surface, where Tp represents the depth of the depression of the recording layer from the interface between the recording layer and the reflection layer in the pit of the third groove. And the reflective layer 31. The optical information recording medium according to claim 26, wherein Tgi = Tgo <Tgb <Tpb <Tp, where Tpb represents the depth of the depression of the recording layer from the interface. . The pits formed in the same groove of the groove are composed of a first pit and a second pit having a length in the groove direction longer than the first pit, and a maximum width of the first pit in a substrate radial direction. the expressed as _{W 1,} when the maximum width of the substrate radially in the second pit expressed in _{W 2,} claim 26-31, which is a _{1 ≦ W 2 / W 1 <} 1.2 The optical information recording medium according to claim 1. The optical information recording medium according to any one of claims 26 to 32, wherein the organic dye material is an azo dye material. A method for manufacturing an optical information recording medium according to any one of claims 26 to 33,
By irradiating the photosensitive material formed on the master with an exposure intensity that continuously changes from the inside to the outside of the master, the first groove, the third groove, and the fourth groove are applied to the photosensitive material. The pattern corresponding to the grooves of the second groove, the pits of the third groove, and the pits of the fourth groove are exposed on the photosensitive material by irradiating the pattern corresponding to the groove of the groove and irradiating the photosensitive material with three different exposure intensities. To do;
Forming a pattern corresponding to the first groove, the second groove, the pitted third groove and the pitted fourth groove by performing development and etching by RIE on the master after the exposure;
Forming a substrate using the master on which the pattern is formed;
Forming a recording layer and a reflective layer on the substrate. The exposure intensity at the time of exposing the pattern corresponding to the pit is first set to the first exposure intensity, then to the second exposure intensity lower than the first exposure intensity, and further to the first exposure intensity. 35. The method for manufacturing an optical information recording medium according to claim 34, wherein: 36. The light according to claim 35, wherein when a clock cycle for reproducing the optical information recording medium is represented by T, the period of exposure at the first exposure intensity is set to 1T to 1.5T, respectively. Manufacturing method of information recording medium. The method for manufacturing an optical information recording medium according to any one of claims 34 to 36, comprising, when exposing the master, setting the exposure intensity to 0 in addition to the exposure intensity. 38. The method for manufacturing an optical information recording medium according to claim 34, wherein the etching by RIE is performed by changing a flow rate of a gas used for RIE between inside and outside of the master. A master used in the method for manufacturing an optical information recording medium according to claim 9, wherein the master is made of glass. A stamper manufactured by using a master used in the method for manufacturing an optical information recording medium according to claim 9.

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