JP2000011466A - Sputter holder for optical recording medium and production of optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity and to ameliorate the mechanical characteristics, such as warpage, tilt and acceleration, of an optical recording medium after sputtering with a simple process by using a porous member consisting of ceramics in constituting the section of a holder for holding the substrate of the optical recording medium at the time of sputtering, which section comes into contact with the substrate. SOLUTION: A holder 4 holds the substrate 1 of the optical recording medium 1 of <=0.6 mm in thickness formed by injection molding of a thermoplastic resin with an outer mask 2 and center mask 3 of the outer peripheral and inner peripheral portions of the same height. The holder 4 holds the substrate 1 in a horizontal state and the contact surface of the holder 4 and the substrate 1 is provided with the porous member 6 of the ceramics. The substrate 1 is attracted to the horizontal porous member 6. If sputtering is executed in this state, the warpage is usually generated in the substrate 1 by the stress of the sputter film and strains are decreased by the attraction of the horizontal porous member 6. As a result, the recording layer is crystallized on the sputter film and the optical recording medium having the decreased strains is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputter holder for an optical recording medium and a method for manufacturing an optical recording medium. The present invention relates to a sputter holder for an optical recording medium for producing an optical recording medium with less distortion by improving mechanical characteristics such as warpage, tilt, and acceleration of the optical recording medium, and a method for manufacturing an optical recording medium using the same.

[0002]

2. Description of the Related Art An optical recording medium is provided with an optical recording / reproducing information recording section on a molded substrate, and is used as a disk for files such as documents and data. While rotating the optical recording medium at high speed, a laser beam narrowed down to about 1 μm is irradiated to read data from the recording layer or record data on the recording layer while performing focus adjustment and position detection.

The following is an example of a specific recording / reproducing method for a phase change type optical recording medium. During recording, a focused laser pulse is applied to the crystalline recording layer for a short time to partially melt the recording layer. The melted part is quenched by heat diffusion,
It solidifies to form an amorphous recording mark. If the reflectance of the recording mark is set lower than, for example, the crystalline state, information can be optically reproduced using the reflectance difference. Further, at the time of erasing, the recording mark portion is irradiated with laser light, and the recording mark in the amorphous state is crystallized by heating to a temperature lower than the melting point of the recording layer and higher than the crystallization temperature,
Return to the original unrecorded state.

[0004] As the recording layer material, an alloy such as Ge ₂ Sb ₂ Te ₅ as a main component and tellurium (N.Yamada e
t al, Proc.Int.Symp.on Optical Memory 1987 p61-
66) are known. Such an optical recording medium having a Te alloy as a recording layer has a high crystallization speed and can perform high-speed overwriting with one circular beam only by modulating the irradiation power. In optical recording media using these recording layers, usually, a heat-resistant and light-transmitting dielectric layer is provided on both sides of the recording layer to prevent the recording layer from being deformed and opened during recording. .

[0005]

In the production of such an optical recording medium, generally, a substrate is fixed to a holder using an outer mask and an inner mask, and a recording film is formed by a method such as sputtering.
This is performed by forming a protective film or the like. Thereafter, the optical recording medium is manufactured through a process such as overcoating, and it is important in manufacturing to manage the optical recording medium to be manufactured so that the mechanical characteristics of the manufactured optical recording medium are not deteriorated due to the film stress at the time of sputtering.

In recent years, in the production of optical recording media,
In order to improve production efficiency, the sputtering time tends to be shortened for the purpose of shortening the tact time, but the sputtering time is often shortened by increasing the sputtering power. In particular, in an optical recording medium having a dielectric layer, the dielectric layer is formed by sputtering using a radio frequency (RF) power supply.
When the sputter power is increased, the substrate surface temperature increases during the formation of the dielectric layer, causing a problem that the distortion of the resin substrate increases. This problem also applies to the formation of another layer, for example, a recording layer.

Therefore, in order to lower the substrate temperature during sputtering, it is conceivable to suppress the rise in the substrate surface temperature by a method of lowering the sputtering power or a method of increasing the distance between the substrate and the target. However, in order to lower the substrate temperature, it is necessary to greatly reduce the sputter rate, and the production efficiency is extremely deteriorated. It is also conceivable to forcibly cool the substrate at the time of sputtering, but it has a drawback that the process becomes complicated because a cooling device is required.

Further, in order to achieve a higher density of an optical recording medium by reducing the size of a recording mark, an optical head having a large numerical aperture capable of narrowing a laser beam is being used in a drive. Furthermore, the substrate of the optical recording medium has been changed from a 1.2 mm thick substrate used in CDs and CD-ROMs to a 0.6 mm thick so that stable recording and reproduction can be performed even when an optical head having a larger numerical aperture is used. In the direction of thinning. For this reason, it is necessary to more strictly manage the mechanical properties of the substrate which affect focusing and tracking during recording and reproduction.

An object of the present invention is to improve the above-mentioned problems,
While improving the productivity in the production of optical recording media and improving the mechanical properties such as warpage, tilt, and acceleration of the sputtered substrate with a simple process without significant improvement in equipment, An object of the present invention is to provide a sputter holder for an optical recording medium for manufacturing a recording medium and a method for manufacturing an optical recording medium.

[0010]

Means for Solving the Problems To solve the above problems, the present invention comprises the following constitutions. That is, the optical recording medium sputter holder of the present invention is a holder for holding an optical recording medium substrate during sputtering, wherein a portion of the holder that holds the substrate that contacts the substrate is porous. Is what you do.

Further, the method for manufacturing an optical recording medium according to the present invention comprises:
What is claimed is: 1. A method for manufacturing an optical recording medium in which an optical recording medium substrate is sputtered while being held by a holder, wherein a portion of the holder which holds the substrate, which is in contact with the substrate, is porous.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings.

FIG. 1 is a sectional view showing an embodiment of the sputter holder of the present invention, and FIG. 2 is a plan view cut along AB of FIG. FIG. 3 is a sectional view of a conventional sputter holder.

As shown in FIG. 3, a sputter holder for an optical recording medium generally holds a recording medium substrate 1 on a holder 4 by an outer mask 2 and a center mask 3 at the outer periphery and the inner periphery at the same height. 1 is kept in a horizontal state. Also, the holder 4 has a structure having a recessed portion 5 so that the surface where the substrate 1 contacts the holder 4 is reduced.

The holder according to the present invention is characterized in that, as shown in FIG. 1, for example, a porous member 6 is provided on the surface of the holder 4 which comes into contact with the substrate 1.

Usually, the substrate 1 is warped due to the stress of the sputtered film. However, by adsorbing the substrate 1 on the horizontal porous member 6 and sputtering, the distortion of the substrate 1 due to the stress of the sputtered film is reduced. An optical recording medium having good mechanical properties can be obtained.

With respect to the portion of the holder 4 which is in contact with the substrate 1 as the porous member 6, the entire surface of the holder 4 which is in contact with the substrate may be constituted by a porous member. In order to improve the characteristics, only a part of the holder may be made of a porous member.

As the material of the porous member, for example, ceramics can be used.

The optical recording medium according to the present invention has at least a recording layer and a protective layer on a substrate. Preferably, it has a plurality of laminated structures, for example, a first layer (first protective layer) / second layer (recording layer) / third layer (second protective layer) / fourth layer (reflection) on a substrate. Layers) in this order, or a first layer (first protective layer) / second layer (recording layer) /
Third layer (second protective layer) / fourth layer (light absorbing layer) / fifth layer (reflective layer) and the like.

The effects of the first and second protective layers are as follows: prevention of corrosion of the recording layer, prevention of deterioration of recording characteristics caused by heat deformation of the substrate and the recording layer during recording, and signal contrast at the time of reproduction due to an optical interference effect. Has the effect of improving. In this case, the thickness of the first protective layer is usually 50 nm to 400 nm. The thickness of the second protective layer is preferably 10 nm to 100 nm, because it is excellent in that the recording characteristics are not deteriorated due to rewriting repeatedly and the power margin of the erasing power is wide.

As such a protective layer, ZnS, Si
O ₂ , Ta ₂ O ₅ , ITO, ZrC, TiC, MgF ₂
Inorganic films such as these and mixed films thereof can be used. Especially Zn
A mixed film of S and SiO ₂ or ZnS and MgF ₂ is preferable because it has excellent long-term storage reliability and suppresses deterioration at the time of recording / erasing. Further, those obtained by mixing carbon or a fluoride such as MgF _{2 with} these are also preferable because the residual stress of the film is small. Especially mixed film of ZnS and SiO ₂ or a mixed film of ZnS and SiO ₂ and carbon are recorded, even by the repetition of erasing and recording sensitivity, C / N, preferably in particular ZnS since does not occur easily deteriorate, such as erasure ratio Si
A mixed film of O ₂ and carbon is preferred.

As the recording layer, it is preferable to use an alloy containing at least three elements Ge, Sb, and Te as constituent elements from the viewpoint that overwriting can be performed at high speed. Further, the composition is preferably within the range represented by the following formula, from the viewpoint of excellent thermal stability and repetition stability.

M _z (Sb _x Te _1-x ) _1-yz (Ge _0.5 Te _0.5 ) _y 0.35 ≦ x ≦ 0.5 0.2 ≦ y ≦ 0.5 0.0005 ≦ z ≦ 0.01 Here, M represents at least one metal selected from palladium, niobium, platinum, silver, gold and cobalt, Sb represents antimony, Te represents tellurium, and Ge represents germanium. In addition, x, y, z, and numerals represent the number of atoms of each element (the number of moles of each element). In particular, palladium and niobium preferably contain at least one kind.

The light reflection layer formed on the second protective layer or the light absorption layer improves the signal contrast at the time of reproduction by an optical interference effect, and has an amorphous recording mark by a cooling effect. Facilitates the formation of the
The effect of improving the repetition characteristics is expected. The thickness of the recording layer is preferably from 10 to 100 nm.

As a material of the reflection layer, a metal such as Al or Au having light reflectivity and a material containing these as main components,
alloys containing additional elements such as i, Cr, Hf and Al,
Examples include a mixture of a metal such as Au and a metal compound such as a metal nitride such as Al and Si, a metal oxide, and a metal chalcogenide. Metals such as Al and Au and alloys containing these as main components are preferable because of high light reflectivity and high heat conductivity. Examples of the aforementioned alloys include Al, Si, Mg, Cu, Pd, Ti, Cr,
At least one element such as Hf, Ta, Nb, Mn or the like added in a total of 5 atomic% or less and 1 atomic% or more, or at least one element of Au, Cr, Ag, Cu, Pd, Pt, Ni, etc. Element total 20 atomic% or less 1 atomic%
These are the ones added above. In particular, an alloy containing Al as a main component is preferable because the cost of the material can be reduced. In particular, since the corrosion resistance is good, T
i, Cr, Ta, Hf, Zr, Mn, Pd and at least one metal selected from the group consisting of at most 5 atomic%
Alloys containing at least atomic% are preferred. In particular, Al-Hf-Pd alloys, Al-Hf alloys, Al-Hf alloys containing a total of 0.5 to less than 3 atomic% of additional elements because of good corrosion resistance and low occurrence of hillocks and the like.
Ti alloy, Al-Ti-Hf alloy, Al-Cr alloy, A
l-Ta alloy, Al-Ti-Cr alloy, Al-Si-M
Any of the n-alloys containing Al as a main component is preferable as the material of the reflective layer.

As a substrate for a recording medium, it is preferable to use a material through which laser light can be transmitted in order to perform recording / reproduction from the substrate side. For example, polymethyl methacrylate resin, polycarbonate resin, polyolefin resin, epoxy resin, etc. Organic polymer resins, mixtures thereof, copolymers and the like can be used. Among them, a polycarbonate resin can be most preferably used from the viewpoint of optical characteristics and heat resistance.

Using this thermoplastic resin, a disk-shaped substrate is produced by, for example, injection molding or injection compression molding. At the time of molding the substrate, a stamper having a predetermined groove or pit male mold formed on the surface is mounted in a mold, and a substrate having a desired track formed on the surface by transfer from the stamper is molded.

The size of the substrate needs to conform to the standard required by the optical recording medium drive. For example, the diameter is 80 mm, 90 mm, 120 mm or 130 mm
Substrates are defined. A thickness of 1.2 mm to 0.6 mm is usually used, but the effect of the present invention is more pronounced when the substrate thickness is smaller, so that the effect is high when the thickness is 1 mm or less, particularly 0.6 mm or less.

On such a substrate, at least the above-mentioned layers are laminated with an appropriate thickness as required. An organic resin protective layer may be provided on this layer. As the organic resin protective layer, a photocurable resin composition containing a polymerizable monomer and an oligomer as a main component, and a thermosetting resin composition are used,
Generally, it is formed by a spin coating method. In addition, a protective layer made of a similar organic resin composition is provided on the substrate on the light incident surface side for the purpose of protecting the substrate such as abrasion resistance and printing durability,
It may be provided for the purpose of imparting antistatic properties to prevent dust adhesion.

[0030]

EXAMPLE 1 Using a holder shown in FIG.
An optical disk was manufactured by sputtering a thin film having the following structure on a transparent substrate made of 0 mm polycarbonate using a sputtering apparatus. The thickness of each layer was monitored while monitoring with a crystal oscillator type thickness meter. Ceramics were used as the porous member.

An optical recording medium was obtained by forming an acrylic ester-based ultraviolet curable resin to a thickness of 8 μm on the sputter surface of the obtained disk by spin coating. Further, the optical recording medium was irradiated with a semiconductor laser beam having a wavelength of 820 nm to crystallize and initialize the recording layer on the entire surface of the disk.

First layer First protective layer 80 ZnS-20SiO ₂ (mol%) 160 nm Second layer Recording layer 55Te19Ge26Sb 25 nm Third layer Second protective layer 80 ZnS-20SiO ₂ (mol%) 40 nm Fourth layer Reflective layer Al 100 nm After standing at 23 ° C. and 50% humidity for one day, the mechanical properties of the optical recording medium were measured with a mechanical property measuring device (LM100, manufactured by Ono Sokki Co., Ltd.). Table 1 shows the disk warpage (DEF) and the tilt angle at the outer peripheral portion (radius 56 mm) of the recording medium.

Example 2 An optical disk was produced in the same manner as in Example 1 except that the thickness of the substrate was changed as shown in Table 1. Table 1 shows the results.

Comparative Examples 1 and 2 Discs were prepared in the same manner as in Example 1 except that the thickness of the substrate was as shown in Table 1 and the holder shown in FIG. 3 was used. Table 1 shows the results.

[0035]

[Table 1] The results shown in Table 1 show that the use of the holder of the present invention improves the mechanical properties of the optical recording medium.

[0036]

According to the present invention, in the production of an optical recording medium, not only the productivity is improved, but also the mechanical properties such as warpage, tilt, acceleration and the like of the optical recording medium after sputtering are improved by a simple process, and the distortion is improved. It is possible to manufacture an optical recording medium having a small amount of light.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a sputter holder of the present invention.

FIG. 2 is a plan view taken along a line AB in FIG. 1;

FIG. 3 is a cross-sectional view of a conventional sputter holder.

[Explanation of symbols]

 1: substrate 2: outer mask 3: center mask 4: holder 5: depression 6: porous member

Claims (4)

[Claims] An optical recording medium sputtering apparatus comprising: a holder for holding an optical recording medium substrate at the time of sputtering, wherein a portion of the holder for holding the substrate which contacts the substrate is formed of a porous member. holder. 2. The sputter holder for an optical recording medium according to claim 1, wherein the porous member is made of a ceramic. 3. A method of manufacturing an optical recording medium, comprising: using a holder for holding a substrate having a portion that is in contact with the substrate with a porous member and holding the optical recording medium substrate with the holder to perform sputtering. Method. 4. A substrate having a thickness of 0.6 mm or less, which is obtained by injection molding a thermoreversible resin.
The manufacturing method of the optical recording medium according to the above.