JPH07334874A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To efficiently and easily produce an optical recording medium by injecting the forming material of a functional layer having different film thickness in an oblique direction to the substrate surface so that a larger amt. of the material is deposited on the area corresponding to the land part than on the area corresponding to the groove part. CONSTITUTION:The production device is set in such a manner that the film deposition direction A of the film forming material by a thin film forming means and the plane of the substrate 1 make a specified angle theta. Then the forming material is gradually deposited in an oblique direction on the area where grooves 2 of the substrate 1 are formed. Thereby, a larger amt. of the material is deposited on the area corresponding to the land part 3 than on the area corresponding to the groove part 2. Therefore, such an optical recording medium can be easily and efficiently produced that has the functional layer 4 in which thickness d3 of the layer in the area corresponding to the land 3 is larger than the thickness d2 of the layer in the area corresponding to the groove 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an optical recording medium in which a functional layer having a relatively large layer thickness in a land portion corresponding region is formed between a groove portion of a substrate and a region corresponding to a land portion therebetween. .

[0002]

2. Description of the Related Art A disk type optical recording medium has a tracking control for precisely following a predetermined track with a laser beam of a predetermined size for scanning (writing) and reproducing (reading), and its laser. Focusing control is required to accurately focus the beam. In addition, scanning control in the track direction may be performed in order to remove the jitter component. In particular, regarding the above tracking control, there are a three-beam method and a push-pull method as main control methods, and both have their own advantages and disadvantages. However, at present, the three-beam method is for commercial use. It is often used for optical disc drives such as CDs (compact discs) and LDs (laser discs), and one push-pull method is often used for optical disc drives for data processing. Despite the high cost of parts, this 3-beam method is often used for optical disk drives such as CDs and LDs because of the ease of tracking control It is believed to be due to the large number of usage records.

By the way, a read-only type CD-R
The specifications of OM-related optical recording media are strictly defined by standards. Specifically, the recording mode is “High to lo” in which the reflectance of the recording layer is lowered by optical recording.
w ”type, the initial reflectance of the recording layer is 70%
By setting the above-mentioned setting and lowering the reflectance of the mark portion formed by recording by the phase structure, it is possible to obtain a contrast of a predetermined value or more with respect to the initial reflectance.

Further, the writable write-once type CD-related optical recording medium has the specifications of Orange Book Part II.
It is regulated by the standard. According to the standard, it is premised that the recording mode is "High to low" type, the initial reflectance of the recording layer is set to 65% or more, and the reflectance of the mark portion is lowered by writing. The contrast above a certain level is generated with respect to the initial reflectance. The reduction of the reflectance of the mark portion is performed by thermally deforming the dye layer in the basic medium structure of Au layer / organic dye layer / substrate by laser beam irradiation.

The three-beam type tracking control for these optical recording media is performed as follows. That is, in the case of the former medium, the decrease in reflectance at the mark portion is directly detected as the dark and light pits, and in the case of the latter medium, the writing portion is the narrow groove portion () formed on the disc substrate. Narrow groove)
Is set, and before and after writing, a decrease in reflectance at the mark portion along the groove portion is detected as a dark and light pit, which is performed.

As described above, in the normal three-beam type tracking control, the tracking polarities are set so that the control main beam follows the dark portion on the optical recording medium. In short, in the read-only type optical recording medium, the recorded mark portion (column) functions as a dark track due to the decrease in reflectance, and in the write-once recording medium, the groove portion is compared to the land portion between them. In this way, the main beam follows these dark tracks to perform tracking control by the three-beam method.

The present applicant has previously proposed a CD write-once (WO) type optical recording medium which can be written at least once using a phase separation type recording material. . The CD-WO type optical recording medium to which the phase-separated recording method is applied has “High to low” and “Low tohi” recording modes.
gh ”(optical recording increases the reflectance of the recording layer),
It is possible to adopt three types of modes of "Middle toe and high" (the reflectance of the recording layer having an initial reflectance at an intermediate level is lowered and increased by optical recording).

[0008]

However, this C
The recording mode of the D-WO type optical recording medium is "High.
h to low ”or“ Middle to lo ”
In the case of the "w and high" type, the tracking control of the three-beam method can be applied, but in the case of the recording mode of the "Low to high" type, the application thereof is difficult.

That is, in the case of the "Low to high" type recording mode, the reflectance of the mark portion becomes higher due to the optical recording, and the average reflectance of the mark portion row becomes higher than that between the mark portion rows. In the tracking error detector, the mark portion row is detected as a light portion track, and the space between the mark portion rows is detected as a dark portion track, and as a result, the control main beam is not drawn into the mark portion row, This is because they are drawn between the mark portions and follow.

In this way, "Low to high"
Only in the case of the recording mode of the type, that is, the optical recording medium of the reflectance increasing type, it is difficult to apply the tracking control by the three-beam method with the constitution contents so far. Therefore, this type of optical recording medium may not be normally played back by a general popular CD player (playback device).

Therefore, the inventors of the present invention have conducted various studies in order to solve the above-mentioned problems (particularly, the difficulty of applying the tracking control by the three-beam method to the reflectance increasing optical recording medium), and as a result, interference The layer thickness of the functional layer such as the recording layer and the recording layer may be appropriately made different between the regions corresponding to the groove portion and the land portion of the substrate, for example, the layer thickness of the region corresponding to the land portion may be different from that of the region corresponding to the groove portion. It has been found that the above problems can be solved by making the thickness larger than the layer thickness.

Therefore, the present invention has been made on the basis of the above-mentioned findings, and the purpose thereof is to make the layer thickness of the region corresponding to the land portion thicker than the layer thickness of the region corresponding to the groove portion. An object of the present invention is to provide a method for easily and efficiently manufacturing an optical recording medium on which a functional layer is formed.

[0013]

That is, according to the method of manufacturing an optical recording medium of the present invention, a predetermined functional layer laminated on a substrate on which a groove is formed is provided in an area corresponding to a land portion between the groove portions. Is a method for manufacturing an optical recording medium in which the layer thickness is formed to be relatively thicker than the layer thickness of the region corresponding to the groove portion, and the functional layer forming material that makes the layer thickness different is formed on the substrate surface. On the other hand, it is characterized by projecting from an oblique direction and depositing more on the region corresponding to the land portion than on the region corresponding to the groove portion.

In this technical means, the functional layers having different layer thicknesses are formed by a so-called oblique film formation method in which the forming material is obliquely projected and deposited on the substrate surface. The oblique film forming method utilizes thin film forming means such as RF sputtering method, ion beam sputtering method, vapor deposition method, CVD method, etc., and as shown in FIG. ) After setting so that the direction A and the surface of the substrate 1 form a predetermined angle θ, the forming material is gradually deposited on the surface of the substrate 1 on the side where the groove 2 is formed from the oblique direction. . As a result, the groove portion 2 of the substrate 1 and the land portion 3 between them are formed.
Between the regions corresponding to (3), the layer thickness d ₃ in the region corresponding to the land part 3 is larger than the layer thickness d ₂ in the region corresponding to the groove part 2 because a larger amount is deposited on the region corresponding to the land part 3. Layer 4 is obtained.

For example, when the sputtering method is used as the thin film forming means, as shown in FIG. 2, the substrate 1 is inclined at a predetermined angle with respect to the direction A of the sputtered particles flying from the target 10. It is installed by inclining by θ and depositing sputtered particles on the substrate 1 in that state. In this case, a slit 12 having a predetermined opening 11 is used as shown in FIG.
It is possible to deposit only the sputtered particles in the range passing through the opening 11 on the substrate 1 while controlling and adjusting the direction A of the sputtered particles flying from the target 10 and entering through the slit 12.

The form of the optical recording medium is not particularly limited, and in addition to a disc type such as an optical disc,
It may be a card type such as an optical card, but in any form, it is preferable that the oblique deposition film is performed while rotating the substrate. When the oblique deposition film is formed in this manner, it is possible to form the functional layer having a desired layer thickness condition, much more efficiently than when the substrate is fixed.

For example, a disk using the sputtering method
When the oblique film formation is carried out while rotating the substrate 1 in the shape of FIG.
As shown in FIG.
Two targets 10a, 1 facing each other in the lateral position
0b is installed and 2 directions A by each target₁, A₂From
By depositing sputtered particles of
be able to. At this time, the spatter from each target
Projection direction A ₁, A₂The angle formed by the
It is preferable that they are almost equal. Both angles are large
If the widths are different, the film formation is
It becomes a name when tracking control and track counting
May hinder the operation.

In this case, the film deposition is roughly performed in two states. That is, when the rotating substrate 1 is close to the target 10 (PP portion) as shown in FIG. 4, the sputtered particles are mainly deposited on the land portion 3 of the substrate 1 as shown in FIG. On the other hand, when the substrate 1 that has been deposited and is rotating as shown in FIG.
In the portion (Q portion), the sputtered particles are deposited in substantially the same amount on both the groove portion 2 and the land portion 3. This allows
As a result, the sputtered particles are deposited more on the region corresponding to the land portion 3 than on the groove portion 2.

In this case, if necessary, a mask member 13 is provided between the substrate 1 and the target 10, which is a region away from the target 10, so that the rotating substrate 1 is separated from the target 10. It is possible to adjust the degree of film formation by preventing (suppressing) the film formation of (2), particularly the film formation on the groove 2. Furthermore, if necessary, two targets may be installed in addition to the targets 10a and 10b, and the sputtering particles may be projected from four directions. Also in this case, a mask member may be appropriately provided between the targets to adjust the film deposition degree, if necessary.

Projection direction A of the film-forming material on the oblique film formation
The angle θ between the surface of the substrate 1 and the surface of the substrate 1 is defined by the groove 2
It is desirable to set the angle such that the material projected toward the direction is blocked (or reduced) by the land portion 3 and does not reach (or is suppressed) the groove portion 3. Preferably, the angle θ is set to such an angle that the non-reaching area of the projection direction A to the bottom surface of the groove portion 3 is half or more because it is shielded by the land portion 3. When this angle θ is set to be larger than the above angle, it becomes difficult to make a difference in film deposition degree between the groove portion and the land portion, and thus it becomes difficult to form a target functional layer. On the other hand, if the angle θ is too small, the film forming speed becomes slow, and the production efficiency decreases.

According to the method of the present invention, the ratio of the film thicknesses of the regions corresponding to the land portions and the groove portions is 1.2: 1 to 10 :.
It is possible to easily form the functional layer in the range of 1. In particular, if the ratio is in the range of 1.5: 1 to 3: 1, it can be formed more easily and efficiently. The layer thickness of the functional layer in the region corresponding to the land is preferably 1000 nm or less. If the layer thickness is made thicker than this, the deposition rate in the oblique film formation method is inferior to that in a normal thin film forming method, and the productivity becomes poor.

The functional layers having different layer thicknesses are mainly interference layers.
And a recording layer, but also a cooling layer and a protective layer.
Good. When forming an interference layer as a functional layer, the interference
SiO as a layer forming material₂, ZnS-SiO₂Repelled
Therefore, SiN, SiC, TiO ₂, ZnS, Al₂O₃, A
1N, Ta₂O_Five, DLC (Diamond Like C
Arbon) and other materials mainly composed of dielectric materials are used.
can do. Moreover, the reflectance is optical recording as a recording layer.
To form a reflectance-increasing type that increases with
In this case, the recording layer material is, for example, a phase separation type spin layer.
Recording material that utilizes nodal decomposition can be used
It

In the method of the present invention, the material to be projected is also deposited on the step portion 3a between the groove portion and the land portion, so that the film on the portion 3a is deposited as little as possible. It is necessary to design the width of the parts and lands and set each condition. The film on this step is
When the layer thickness of the region corresponding to the land portion is small, there is no problem, but when the layer thickness is large, some trouble may be caused.

Further, according to the present invention, the reflectance characteristics can be made different between the regions corresponding to the groove portion and the land portion due to the difference in the thickness of the functional layer having the different layer thickness.
Therefore, if the optical recording medium is designed so that the corresponding region of the groove portion or the land portion where the reflectance becomes low is used as a track, the track portion functions as a dark portion, so that the tracking control method of the three-beam method is applied. It can be possible. In addition to this, due to the difference in the thickness of the functional layer, the phase of the reflected light can be made different between the regions corresponding to the groove portion and the land portion. Therefore, if the optical recording medium is designed so that the corresponding region of the groove portion or the land portion where the phase with respect to the reflected light advances is used as a track, it becomes a medium applicable to the tracking control method of the push-pull method as well as the 3-beam method. can do.

[0025]

According to such a manufacturing method, since the material for forming the functional layers having different layer thicknesses is projected obliquely to the substrate surface, a part of the projected material is blocked by the land portion. The arrival at the groove portion is prevented or reduced (see the chain line S in FIG. 1). As a result, the forming material is deposited more on the region corresponding to the land portion than on the region corresponding to the groove portion, so that the layer thickness of the region corresponding to the land portion is larger than that of the region corresponding to the groove portion. An optical recording medium having a thick functional layer can be easily obtained.

[0026]

EXAMPLES The present invention will be specifically described below based on examples.

Example 1 In this example, an optical recording medium having a medium structure as shown in FIG. 7 was manufactured. That is, in the optical recording medium of this example, a disc-shaped polycarbonate substrate 1 (land portion 3 having a width of 1000 nm) having a groove portion 2 (depth 200 nm, width 600 nm) was formed on the substrate 2. The protective layer 5 made of SiO ₂ and having a thickness of 80 nm, the recording layer 6 made of Sb-O and having a thickness of 40 nm, and SiO
The interference layer 7 is made of ₂ and has a thickness of 60 nm, the reflection layer 8 is made of AlTi and has a thickness of 60 nm, and the surface protective layer 9 is made of an ultraviolet curable resin and has a smooth surface. Further, this optical recording medium is of the reflectance increasing type, and the area corresponding to the land portion 3 is used as a track for optical recording.

Here, the interference layer 7 as a functional layer having a different layer thickness was formed by the following oblique sputtering method. The protective layer 5 and the reflective layer 8 were formed by a normal RF sputtering method, the recording layer 6 was formed by an ion plating method, and the surface protective layer 9 was formed by a spin coating method.

That is, the interference layer 7 was formed by using a sputtering device having the following structure. Figure 8
Shows schematically the configuration of the sputtering apparatus. In the figure, 20 is a chamber, 21 is a substrate transfer holder for transferring the inside of the chamber 20 in the direction of the arrow S while rotatably holding the substrate 1, and 22 is a mask arranged along the transfer path in the chamber 20. Is the target, 12
Shows a slit 12 formed by inclining a plurality of slit plates at a predetermined angle and arranging the slit plates at predetermined intervals. Also,
This sputtering device is an in-line type.
Then, on the substrate 1 transported by the substrate transport holder 21, a recording layer or a protective film which is a lower layer of the interference layer is laminated in another chamber room which is continuously connected to the front side of the sputtering apparatus. It is like this.

First, the substrate 1 on which the recording layers and the like have already been laminated is rotated by the substrate carrying holder 21,
The center of the chamber 20 is transported in the direction of arrow S, and the targets 10 installed on both sides of the transport path perform sputtering from an oblique direction. This oblique sputtering is performed through the slit 12 in order to suppress divergence of sputtered particles. At this time, the incident angle of SiO2, which is the sputtered particle, on the substrate 1 was set to be about 10 °. The layer thickness to be deposited is adjusted by appropriately setting the substrate transport speed, sputtering power, and the like.

At this time, the ratio of the film thickness of the land portion to the groove portion of the substrate 1 was adjusted by the mask 22. That is, the film deposition (deposition) rate in the groove portion of the substrate 1 was suppressed by the mask 22. The mask 22 may not be installed depending on the design content such as film deposition conditions.

The substrate 1 is transported by transporting it in the chamber 20 in which such oblique sputtering is performed.
The interference layer 7 having a layer thickness of 110 nm in the portion corresponding to the land portion 3 and a layer thickness of 40 nm in the portion corresponding to the groove portion 2 was formed (FIG. 7).

When the reflectance of the obtained optical recording medium was measured, the reflectance of the track portion was 30% or less and the reflectance between the track portions was 50% or more. In addition, it was confirmed that the phase of the reflected light at the track portions of this optical recording medium leads the phase of the reflected light between the track portions. Then, using this optical recording medium, an attempt was made to perform recording by a CD writing device of the push-pull type tracking control method and reproduction by a CD player of the three-beam type tracking control method. In both cases, normal recording and reproduction were possible. It was

Example 2 As a substrate 1, a groove portion 2 (depth 210 nm, width 100)
0 nm) and a land part 3 (width 600 nm) are made of polycarbonate, and SiO ₂ protection in which the land part has a layer thickness of 340 nm and the groove part has a layer thickness of 240 nm by oblique RF sputtering. An optical recording medium was produced in the same manner as in Example 1 except that the layer 8 was formed and the interference layer 7 was formed as follows. This optical recording medium uses an area corresponding to the groove portion as a track.

That is, the interference layer 7 was formed by using a sputtering device having the following structure. FIG. 9 schematically shows the configuration of the sputtering apparatus at this time, and this apparatus is the apparatus in Example 1 (FIG. 8) except that the mask 22 has a different configuration.
It has the same configuration as. The mask 22 is
As shown in FIG. 9, openings 11a and 11b having a predetermined shape are formed.

First, as in the case of the apparatus of the first embodiment, the substrate 1 on which the recording layers and the like are already laminated is rotated by the substrate carrying holder 21 while the center of the chamber 20 is moved in the direction of arrow S. The target 10 is transported, and sputtering is performed in an oblique direction with the targets 10 installed on both sides of the transport path. At this time, the incident angle of SiO2, which is the sputtered particle, on the substrate 1 was set to be about 10 °. Then, at this time, the ratio of the film thickness of the land portion to the groove portion of the substrate 1 was adjusted by the mask 22. That is, the film deposition (deposition) speed in the groove portion of the substrate 1 was suppressed by the opening portion of the mask 22.

The substrate 1 is transported by being transported through the chamber 20 in which such oblique sputtering is performed.
The interference layer 7 having a layer thickness of 340 nm in the portion corresponding to the land portion 3 and a layer thickness of 240 nm in the portion corresponding to the groove portion 2 was formed (FIG. 7).

When the reflectance of the obtained optical recording medium was measured, the reflectance of the track portion was 30% or less and the reflectance between the track portions was 50% or more. In addition, it was confirmed that the phase of the reflected light at the track portions of this optical recording medium leads the phase of the reflected light between the track portions. Then, using this optical recording medium, recording by a CD writing device of the push-pull type tracking control method and CD of the three-beam type tracking control method as in the first embodiment.
When I tried to play back by the player, it was possible to record and play back normally.

[0039]

As described above, according to the manufacturing method of the present invention, the functional layer in which the layer thickness of the region corresponding to the land portion of the substrate is thicker than the layer thickness of the region corresponding to the groove portion is formed. The optical recording medium can be manufactured easily and efficiently.

Therefore, the present invention is extremely effective when manufacturing an optical recording medium in which it is necessary to provide a functional layer having such a layer thickness structure. For example, by using the method of the present invention, by producing an optical recording medium having a functional layer in which the layer thickness between regions corresponding to the land portion and the groove portion is appropriately set, that is, an interference layer or a recording layer is formed, Applicable to the tracking control method by the 3-beam method, and it is possible to easily produce an optical recording medium of increased reflectance, which is applicable to the tracking control method by the push-pull method at the same time as the 3-beam method. Become.

[Brief description of drawings]

FIG. 1 is a conceptual diagram for explaining the principle of the manufacturing method of the present invention.

FIG. 2 is a conceptual diagram showing an example of a manufacturing method of the present invention.

FIG. 3 is a conceptual diagram showing another example of the manufacturing method of the present invention.

FIG. 4 is a conceptual top view showing an example of an oblique sputtering method.

5 is a cross-sectional view taken along the line P-P of FIG.

6 is a cross-sectional view taken along the line QQ of FIG.

FIG. 7 is a cross-sectional view showing an example of an optical recording medium obtained by the manufacturing method of the present invention.

8A and 8B schematically show the configuration of a sputtering apparatus of Example 1, where FIG. 8A is a plan view seen from the target side, and FIG. 8B is a sectional view taken along line BB in FIG. 8A. .

9A and 9B schematically show the configuration of a sputtering apparatus of Example 2, where FIG. 9A is a plan view seen from the target side, and FIG. 9B is a sectional view taken along the line BB of FIG. 9A. .

[Explanation of symbols]

1 ... substrate, 2 ... groove portion, 3 ... land portion 4 ... functional layer made different thickness, the thickness of the region corresponding to d ₂ ... groove portion, the layer thickness of the region corresponding to d ₃ ... land portion, A ... Projection direction of forming material, θ ... Angle formed by projection direction and substrate surface.

Claims (1)

[Claims] 1. A predetermined functional layer laminated on a substrate in which a groove is formed, wherein a layer thickness of a region corresponding to a land portion between the groove portions is relatively greater than a layer thickness of a region corresponding to the groove portion. A method of manufacturing an optical recording medium in which the layer thickness is made thicker, the material for forming the functional layer having different layer thicknesses is projected obliquely to the substrate surface, and compared with a region corresponding to the groove portion. And a large amount of it is deposited on a region corresponding to the land portion.