JP2982668B2 - Manufacturing method of optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium for forming an interference layer or a recording layer having a relatively small land portion corresponding region between a groove portion of a substrate and a region corresponding to a land portion therebetween. And a method for producing the same.

[0002]

2. Description of the Related Art In recent years, compact discs (CDs) and C
Optical recording media typified by D-ROMs and the like have reached the stage of practical use, and their research and development are being actively carried out at present, with the attention of transcending magnetic recording media. In particular, as a recent trend, providing compatibility with CDs is one of the major themes. Therefore, various researches and developments on an optical recording medium satisfying the requirements of the CD standard and its recording method are being advanced.

An optical recording medium compatible with a CD is an important requirement from the viewpoint of compatibility, for example, that it can be reproduced by a general CD player which is currently widely used. If the general CD
Player can use "3-beam method" as tracking control
Therefore, it is necessary to be able to cope with the tracking control by the three-beam method.

Accordingly, the present applicant has already proposed an optical recording medium in which tracking control by a three-beam method can be performed as an optical recording medium of an increased reflectivity in which information can be written (Japanese Patent Laid-Open No. 7-1995). 73504).
This is the so-called “Low” in which the reflectance increases due to optical recording.
An optical recording medium having a “to High” type recording layer can generally write (record) information, but cannot perform tracking control by a three-beam method. Therefore, the thickness of the interference layer is limited to the groove portion and land portion of the substrate. The tracking control is made possible by appropriately forming the corresponding regions differently.

The inventors of the present invention have conducted various studies on a technique for coping with tracking control of an optical recording medium having an increased reflectivity by a three-beam method. The thickness of the optical function layer is appropriately changed between the region corresponding to the groove portion and the land portion of the substrate. Specifically, the film thickness of the region corresponding to the land portion is thinner than the region corresponding to the groove portion. By doing so, it has been found that the above problem can be solved.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of such circumstances, and has been made in consideration of the above circumstances. Therefore, an optical film in which the film thickness of a region corresponding to a land portion on a substrate is smaller than that of a region corresponding to the groove portion. It is an object of the present invention to provide a production method capable of producing an optical recording medium on which a functional layer (interference layer or recording layer) is to be formed more simply, efficiently and stably.

[0007]

To achieve the above object,
The method according to claim 1, wherein the thickness of the region corresponding to the land between the groove portions is smaller than the thickness of the region corresponding to the groove portion on the substrate on which the groove portions are formed. A method for manufacturing an optical recording medium, wherein the interference layer is formed by depositing a material for forming an interference layer on a substrate, and then causing an etching beam to be obliquely incident on the substrate surface after film formation. This is characterized in that the region is formed by irradiating more to the region corresponding to the land portion than to the region corresponding to the groove portion.

[0008] The manufacturing method according to the second aspect of the present invention is characterized in that:
An optical recording medium manufacturing method for forming a recording layer in which a film thickness in a region corresponding to a land portion between the groove portions is thinner than a film thickness in a region corresponding to the groove portion on a substrate on which the groove portion is formed. The recording layer is formed such that a recording layer forming material is formed on a substrate, and at the same time, an etching beam is obliquely incident on the substrate surface on which the film is being formed. It is characterized by being formed by irradiating a large amount to a region corresponding to the portion.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a so-called "oblique etching method" is employed as a means for varying the film thickness, in which an etching beam is incident on a substrate surface obliquely to perform etching. ing.
As a means for irradiating the etching beam, for example, a thin film etching means such as an ion beam irradiation type or an electron beam irradiation type can be used.

FIG. 1 shows the formation of an optical functional layer, particularly an interference layer or a recording layer, in which the thickness of the region corresponding to the land portion of the substrate is smaller than the thickness of the region corresponding to the groove portion of the substrate. After setting the surface of the substrate 3 having the groove portion 1 and the land portion 2 between the groove portion 1 and the projection direction of the etching beam EB by the beam type thin film etching means at a predetermined angle θ, Irradiation of the etching beam EB from an oblique direction is performed to perform oblique etching. At this time, the oblique etching
When an interference layer is formed as the optical function layer 4, the substrate 3
This is performed after forming the material for forming the interference layer thereon, and when forming the recording layer as the optical functional layer 4, it is performed simultaneously with forming the material for forming the recording layer on the substrate 3.

As a result, a part of the etching beam EB projected toward a region corresponding to the groove portion 1 is blocked in its course by the land portion, and does not reach (or is suppressed to) the groove portion corresponding region. As a result, the area corresponding to the land 2 is more irradiated than the area corresponding to the groove 1. For this reason,
After the film formation or during the film formation, the optical function layer 4 is subjected to more etching in the region portion 4a corresponding to the land portion 2, and finally, in the region corresponding to the land portion 2, A film thickness d 1 in a region where the film thickness d ₂ corresponds to the groove portion ₁
It is formed to be thinner than that.

For example, when the oblique etching is performed by ion beam etching, as shown in FIG. 2, the substrate 3 is set at a predetermined angle θ with respect to the direction of the etching beam EB projected from the ion beam source 10. The etching is performed by irradiating the substrate with the etching beam EB in this state. Further, in this case, as shown in FIG. 3, a slit 12 having a predetermined opening 11 is used, and while the incident direction of the etching beam EB is controlled by the slit 12, a range where the etching beam EB passes through the opening 11 is used. It is also possible to irradiate only the etching beam on the substrate 3.

In the case where oblique etching is performed while rotating the disk-shaped substrate 3 using ion beam etching, as shown in FIG. The two ion beam sources 10a and 10b are installed so as to face each other, and the etching beams EB ₁ and EB ₂ are projected from the two directions by the respective ion beam sources 10a and 10b to perform oblique etching. . In this case, it is desirable that the projection directions of the etching beams EB ₁ and EB ₂ from the respective ion beam sources and the angle θ between the surface of the substrate 3 are equal to each other. When the angles θ are significantly different from each other, the film formation state becomes left-right asymmetric with respect to the rotational traveling direction, which may cause problems in tracking control and track counting.

In this case, the oblique etching is roughly performed in the following two states. Rotating substrate 3
When is near the ion beam source 10 (PP portion) (FIG. 4), as shown in FIG. 5, the ion etching beam EB is mainly irradiated onto the land portion 2 of the substrate 3,
On the other hand, when the rotating substrate 3 is separated from the on-beam generating source 10 (Q-Q portion), the ion etching beam EB is applied to both the groove portion 1 and the land portion 2 in substantially the same amount. And, overall, the etching beam E
B is more irradiated on the region corresponding to the land portion 2 than in the groove portion 1, and the film in the region corresponding to the land portion 2 is etched more.

In this case, if necessary, a mask member 13 is provided between the substrate 3 which is an area away from the ion beam source 10 and the source 10 (FIG. 4). Can be prevented from being etched away from the ion beam source 10, particularly, the etching of the film in the region corresponding to the groove portion 1 can be adjusted, and the degree of film formation can be adjusted. If necessary, two additional ion beam sources 10a and 10b may be used.
Two ion beam sources may be provided to irradiate the etching beam from four directions. Also in this case, if necessary, the degree of film formation may be adjusted by appropriately disposing a mask member between the ion beam sources.

The angle θ between the projection direction of the etching beam EB and the surface of the substrate 3 in such oblique etching.
The angle may be set so that the etching beam projected toward the groove portion 1 which is a concave portion is blocked by the land portion 2 and does not reach (or is suppressed) the groove corresponding region. Desirably, the angle θ is set so that the area of the etching beam not reaching the bottom surface of the region corresponding to the groove portion by being blocked by the land portion 2 is at least half of the entire bottom surface. If the angle θ is larger than the above set angle, it is difficult to make a difference in the degree of film formation between the groove portion and the land portion, so that a layer having a desired thickness difference is formed. Difficult to do.

The film thickness d _{1 in the} region corresponding to the groove portion of the interference layer or the recording layer, which is an optical functional layer, and the film thickness d ₂ in the region corresponding to the land portion are determined by the groove portion or land on which the recording was performed after the recording. Corresponding area (track)
May be recognized as a “dark portion” and the reflectance characteristic that the corresponding area (between tracks) of the other land portion or groove portion is recognized as a “bright portion” may be obtained. By setting in this way, the optical recording medium
In the three-beam tracking control, the control main beam follows so as to be drawn into an area (track) recognized as a “dark part”, so that the three-beam tracking control is normally performed.

When the film thicknesses d ₁ and d ₂ are set so that a phase difference occurs in the reflected light between the area corresponding to the groove and the land of the optical recording medium, the phase of the reflected light If a groove or a land on which recording progresses is designed to be a track as a recording area, an optical recording medium that can be applied to the tracking control of the push-pull method simultaneously with the three-beam method can be obtained.

Further, the optical recording medium to be manufactured basically has a medium structure in which a protective layer, a recording layer, an interference layer,
It has a laminated structure in which a reflective layer and a surface protective layer are formed in this order. Further, the medium structure is not limited to the above-described structure, and may be a structure in which an underlayer as a protective layer is further formed between the substrate and the protective layer.

As in the present invention, an interference layer having a different film thickness is manufactured by obliquely etching the film after the film is formed, so that a substrate or a layer (recording layer or the like) formed before the interference layer is formed.
Thermal damage to the substrate can be greatly reduced. In addition, when forming an interference layer made of a reactive material such as SiN or the like, if oblique etching is performed at the same time as the formation of the interference layer to form an interference layer having a predetermined thickness, the formation of the interference layer made of the material is difficult. No, the interference layer itself cannot be formed.

On the other hand, by manufacturing recording layers having different film thicknesses by performing oblique etching at the same time as the film formation, it is possible to form a recording layer efficiently and, of course, to form a recording layer forming material. Adhesion with the lower layer can be improved, and a different film thickness can be formed more accurately between the groove portion corresponding region and the land portion corresponding region.

[0022]

Next, an embodiment of the present invention will be described.

Example 1 In this example, an optical recording medium having a medium structure as shown in FIG. 7 was manufactured. That is, on a polycarbonate disk-shaped substrate (refractive index 1.58) 3 on which a groove portion 1 having a depth of 200 nm is formed, a thickness 80 of SiO _{2 is formed.}
groove portion thickness d ₁ consisting nm of the underlayer 5, a recording layer 6 having a thickness of 40nm consisting sbox, SiN is 150n
m, an interference layer (refractive index: 2.0, extinction coefficient: 0) 7 having a land portion thickness d ₂ of 240 nm, and a thickness 60 of Al—Ti
An optical recording medium was formed by laminating a reflective layer 8 having a thickness of 10 nm and a surface protective layer 9 having a smooth surface made of a UV-effective resin in this order. This optical recording medium is of a type having an increased reflectivity, and is of a type in which a recording layer area corresponding to a land portion is used as a track for recording.

In manufacturing the optical recording medium, the interference layer 7 was formed by a method utilizing an oblique etching method as described below. The base layer 5 and the reflective layer 8 other than the interference layer 7 were formed by RF sputtering, the recording layer 6 was formed by ion plating, and the surface protective layer 9 was formed by spin coating.

That is, the interference layer 7 is formed by forming an interference film with a uniform film thickness on the entire surface of the substrate 3 (specifically, the recording layer 6) by an ordinary RF sputtering apparatus, and then obliquely configured as follows. It was formed using an etching apparatus. FIG.
2 schematically shows the configuration of the oblique etching apparatus. In FIG. 8, reference numeral 20 denotes a chamber, and 21 denotes a chamber
A substrate transfer holder for transferring the inside of the chamber, a mask plate 22 disposed along a transfer path in the chamber 20, and an ion beam generation source 10 are provided. This oblique etching apparatus is an in-line type, and another chamber for forming an underlayer, a recording layer, an interference film and the like is continuously connected before and after this oblique etching apparatus.

First, the substrate 3 on which the interference film having a uniform thickness is formed on the recording layer 6 in the previous step is transported in the direction of arrow S in the center of the chamber 20 while rotating by the substrate transport holder 21. Then, an ion etching beam EB is applied obliquely from the ion beam sources 10 arranged on both sides of the transport path. At this time, the etching beam E
The angle θ between the projection direction of B and the surface of the substrate 3 is set to be approximately 10 °. In addition, the divergence of the etching beam EB during irradiation is suppressed by the mask plate 22. In addition, the etching rate at this time is adjusted by appropriately setting conditions such as the transfer speed of the substrate and the acceleration voltage of the ion beam.

By transporting the wafer in the chamber 20 where such oblique etching is performed, as described above, the thickness d _{1 of the} region corresponding to the groove is 150 nm and the thickness d _{2 of the} region corresponding to the land is 240 nm. 7 was formed (FIG. 7). At this time, the film thicknesses d ₁ and d ₂ of the interference layer 7 were adjusted to a predetermined film thickness ratio by adjusting the acceleration voltage of the ion beam to 400 V and 3 A.

When the reflectivity of the optical recording medium manufactured as described above was measured, the reflectivity of the land corresponding area as the track was 30% or less, and the reflectivity of the groove corresponding area between the tracks was 30% or less. The reflectance was 60% or more. The optical recording medium can be recorded by a CD recording apparatus employing push-pull tracking control, and the recorded optical recording medium can be reproduced by a CD player employing 3-beam tracking control. there were.

In addition, the substrate and the recording layer were not thermally damaged during the manufacturing process by the above-mentioned manufacturing process, and thus the characteristics such as the C / N ratio and the jitter were good. Although the interference layer 7 was formed of a reactive material, no problem occurred in the material composition and properties in the oblique etching process. In particular, since an interference film made of a reactive material is formed first, there is little dissociation (due to etching beam irradiation) of N ₂ and O ₂ in the film formation process, and the composition of the interference layer is stable. As a result, it is possible to stably obtain desired optical characteristics.

Example 2 In this example, an optical recording medium having a medium structure as shown in FIG. 9 was manufactured. That is, on a polycarbonate disk-shaped substrate (refractive index 1.58) 3 on which a groove portion 1 having a depth of 130 nm is formed, a thickness 80 of SiO _{2 is formed.}
underlayer 5 having a thickness of ₁ nm and a groove portion thickness d _{1 of} SbOx.
Is 50 nm and the thickness d _{2 of the} land is 0 nm.
An interference layer made of iO ₂ and having a thickness of 60 nm (refractive index 1.4)
5, extinction coefficient 0) 7, 60 nm thick made of Al-Ti
The reflective layer 8 and the surface protective layer 9 made of a UV-effective resin were smoothed in this order to obtain an optical recording medium.
This optical recording medium is of a type having an increased reflectivity, and is of a type in which a recording layer area corresponding to a land portion is used as a track for recording.

In manufacturing the optical recording medium, the recording layer 6 was formed by a method utilizing an oblique etching method as described below. The underlayer 5, interference layer 7, and reflective layer 8 other than the recording layer 6 were formed by RF sputtering, and the surface protective layer 9 was formed by spin coating.

That is, the recording layer 6 is formed by depositing a recording layer forming material on the substrate 3 (specifically, the underlayer 5) by a sputtering apparatus having the following configuration, and simultaneously irradiating the recording layer 6 with an etching beam from an oblique direction. It was formed by performing oblique etching. FIG. 10 schematically shows a configuration of a sputtering apparatus which also serves as an oblique etching apparatus. In FIG. 10, reference numeral 20 denotes a chamber, 21
Is a substrate transfer holder that transfers the inside of the chamber 20 in the direction of arrow S while rotatably holding the substrate 3, and a sputtering target () disposed at a position directly below the substrate transfer holder 21 in the chamber 20. Sb), 1
0 is an ion beam source. The sputtering apparatus also serving as the oblique etching apparatus is an in-line type, and another chamber for forming an underlayer, an interference layer, and the like is continuously connected before and after the sputtering apparatus.

First, the substrate 3 on which the base layer 5 has already been formed in the previous step is transported in the direction of arrow S in the center of the chamber 20 while rotating by the substrate transport holder 21, and is sputtered from directly below the substrate 3. Simultaneously with the projection of the particles SbOx, an ion etching beam EB is irradiated from an oblique direction by the ion beam sources 10 arranged on both sides of the transport path. At this time, the etching beam EB
Is set so that the angle θ between the projection direction and the surface of the substrate 3 is approximately 10 °. In addition, the etching rate at this time is adjusted by appropriately setting conditions such as the transfer speed of the substrate and the acceleration voltage of the ion beam.

By transporting the inside of the chamber 20 in which such sputtering and oblique etching are simultaneously performed, as described above, the thickness d of the region corresponding to the groove portion is obtained.
₁ is 50 nm, the thickness d ₂ of the land portion corresponding region recording layer 6 of 0nm is formed (Fig. 9). At this time, the film thicknesses d ₁ and d ₂ of the recording layer 6 have a predetermined film thickness ratio by adjusting the acceleration voltage of the ion beam and the acceleration voltage of the main beam for controlling the sputtering rate as follows. I did it. That is, the volume velocity of the sputter particles on the land portion was set to zero, and the volume velocity of the sputter particles on the groove portion was set to 100 nm / min. As a result, no recording layer was formed in the land corresponding area.

When the reflectivity of the optical recording medium manufactured as described above was measured, the reflectivity of the land corresponding area as the track was 30% or less, and the reflectivity of the groove corresponding area between the tracks. The reflectance was 60% or more. Further, when the track cross signal of the optical recording medium was examined, a signal having a polarity suitable for a CD recording device employing push-pull tracking control was obtained before writing, and a three-beam tracking control was performed after writing. A signal having a polarity suitable for the adopted CD player was obtained. Then, when this optical recording medium was actually subjected to recording of an EFM signal by a CD recording device employing push-pull tracking control and reproduction by a CD player employing 3-beam tracking control, the recording and reproduction were performed. All were able to be performed normally.

In addition, the recording layer can be formed on the underlayer 5 in such a state that the recording layer is firmly adhered to the substrate by the above-mentioned production. The obtained recording layer had a good surface condition, and a stable recording mark shape was obtained.

[0037]

As described above, according to the manufacturing method of the present invention, the oblique etching method is performed after the film is formed (or simultaneously with the film formation), so that the film thickness of the region corresponding to the land portion of the substrate is obtained. However, an interference layer (recording layer) thinner than the film thickness of the region corresponding to the groove portion can be easily and efficiently manufactured stably.

The optical recording medium on which the interference layer or the recording layer having such a film thickness condition is formed, even if the optical recording medium is configured as an optical recording medium of the reflectivity increasing type, performs tracking control by the three-beam method. Will be applicable to
Therefore, according to the present invention, it is possible to easily produce an optical recording medium of an increased reflectance type applicable to tracking control by the three-beam method.

[Brief description of the drawings]

FIG. 1 is an explanatory view conceptually showing a film forming state and an oblique etching state in a manufacturing method of the present invention.

FIG. 2 is a conceptual diagram of a main part showing an embodiment of an oblique etching method.

FIG. 3 is a conceptual diagram of a main part showing another embodiment of the oblique etching method.

FIG. 4 is a conceptual diagram of a main part showing another embodiment of the oblique etching method.

FIG. 5 is a sectional view taken along the line PP of FIG. 4;

FIG. 6 is a sectional view taken along the line QQ in FIG. 4;

FIG. 7 is a cross-sectional view of a principal part showing the optical recording medium manufactured in Example 1.

FIG. 8 is an explanatory plan view schematically showing a configuration of a manufacturing apparatus used in Example 1.

FIG. 9 is a cross-sectional view of a main part showing an optical recording medium manufactured in Example 2.

FIG. 10 is an explanatory plan view schematically showing a configuration of a manufacturing apparatus used in Example 2.

[Explanation of symbols]

1 ... groove portion, 2 ... land portion, 3 ... substrate, 6 ... recording layer, 7 ... interference layer, the thickness of the region corresponding to d ₁ ... groove portion, the thickness of the region corresponding to d ₂ ... land portion, EB: etching beam.

Claims (2)

(57) [Claims] 1. An optical recording method in which an interference layer is formed on a substrate on which a groove portion is formed, the interference layer being thinner in a region corresponding to a land portion between the groove portions than in a region corresponding to the groove portion. A method of manufacturing a medium, wherein the interference layer corresponds to a groove portion by forming an interference layer forming material on a substrate and then causing an etching beam to enter the substrate surface after the film formation in an oblique direction. A method for manufacturing an optical recording medium, wherein the method is performed by irradiating a region corresponding to a land portion more than a region. 2. An optical recording method in which a recording layer is formed on a substrate on which a groove portion is formed, the recording layer having a thickness corresponding to a land portion between the groove portions being smaller than a film thickness of a region corresponding to the groove portion. A method for manufacturing a medium, wherein the recording layer is formed by forming a recording layer forming material on a substrate, and at the same time, corresponding to a groove portion by causing an etching beam to be obliquely incident on a substrate surface during film formation. A method for manufacturing an optical recording medium, wherein the method is performed by irradiating a region corresponding to a land portion more than a region.