JPH05266519A - Production of information recording medium - Google Patents

Abstract

PURPOSE:To provide a reflection film consisting of an Al alloy having good quality by maintaining an atmosphere mixture composed of argon and nitrogen as the atmosphere in a sputtering chamber. CONSTITUTION:The inside of a vacuum vessel 10 is discharged by a discharge device 13 down to, for example, 3/1000000Torr. The gaseous argon and gaseous nitrogen are then introduced into the vessel 10 so as to attain prescribed mixing ratios to maintain 3/1000Torr in the vessel 10. Further, the gas mixing ratios are gradually changed and the sputtering is executed by using Al-3atom% Zr, Al-2atom% Mo, Al-2atom%, Zr-1atom% Mo alloys, by which the Al alloy film is formed. The formation of the Al alloy film as a reflection layer is well executed when the ratio of mixing the nitrogen with the gaseous argon is <=20%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an information recording medium such as an optical disk, an optical card, an optical tape used for recording and reproducing information.

[0002]

2. Description of the Related Art Recently, by forming a thin film on a substrate and irradiating the thin film with a light beam having information to be recorded, a local change in optical characteristics is caused in the thin film, thereby recording information. Information recording media that can be used have been widely used. Some such information recording media have, for example, a reflective layer provided on a substrate. Aluminum (Al) is usually applied as the reflective layer. However, a film formed of Al alone has poor corrosion resistance and is easily oxidized and deteriorated. Therefore, recently, in order to improve the initial reflectance, corrosion resistance, and repetitive recording / reproducing characteristics of the aluminum reflective layer, aluminum (A
l) etc., zirconium (Zr) or molybdenum (M
The following proposals have been made as an information recording medium using a reflective layer made of a material to which o) or the like is added.

Japanese Patent Application Laid-Open No. 2-128332 discloses a recording medium having an information recording thin film which changes upon irradiation with a recording beam, among inorganic and organic substances formed adjacent to the information recording thin film. Al, Cu, Ag, and Au in contact with at least one protective layer
At least one selected from the group A consisting of
V, Cr, Fe, Co, Ni, Zn, Zr, Nb, M
o, Rh, Pd, Sn, Sb, Te, Ta, W, Ir,
An information recording member provided with a layer containing at least one selected from the group B consisting of Pt, Pb, Bi, and C as a main component is described.

This proposal describes the repetitive characteristics of an information recording medium having a reflective film formed by adding zirconium to aluminum, but does not explain the invention as to the manufacturing method. Absent.

Further, in Japanese Patent Application Laid-Open No. 3-216829, the reflection film formed on the optical disk is formed of Al-Zr and / or
Alternatively, it is described that the reflective film is made of Hf alloy and is formed by sputtering a casting target.

However, a detailed description has not been given on the manufacturing method for sputtering using an Al-Zr alloy target, an Al-Mo alloy target, or an Al-Zr-Mo alloy target.

[0007]

As described above, the characteristics of an information recording medium having a reflective film obtained by adding zirconium, molybdenum, or the like to aluminum have been described in the related art. The method is not described in detail. When such a reflection layer is formed on the substrate of the information recording medium by the sputtering method, the film characteristics of the obtained Al alloy reflection film largely depend on the sputtering conditions.

Therefore, the present invention provides an information recording medium having at least a reflective layer on a substrate, in which aluminum is
It is intended to provide a method for manufacturing an information recording medium, which is capable of obtaining a high quality Al alloy reflective film by using a sputtering method using a material to which zirconium and / or molybdenum is added.

[0009]

According to the method of manufacturing an information recording medium of the present invention, aluminum (Al) and zirconium (zirconium) are formed under the condition that a mixed gas atmosphere of Ar and N _{2 of 20} atom% or less is used in the sputtering chamber. Zr) and at least one selected from the group consisting of molybdenum (Mo) as a target, and a step of forming a reflective layer on the substrate by performing sputtering. If the N ₂ gas exceeds 20 atom%, a good reflective film cannot be obtained.

Further, the N ₂ gas is preferably 0.001 to 20 atom% of the mixed gas atmosphere, and 0.001
If it is less than atom%, the effect of mixing N ₂ gas may not be sufficiently obtained, and a good reflective film may not be obtained.
If it exceeds 20 atom%, the reflective layer material is nitrided to form a semi-transparent film, and sufficient reflection tends not to be performed.

The amount of Zr and Mo added to Al is
There is an appropriate value. Since Zr and Mo have a lower reflectance than Al, if too much is added, the reflectance tends to decrease.

The amount of Zr added to Al is 0.05 to
80 atom% is preferable, and when it is less than 0.05 atom%, the corrosion resistance is not so different from that of Al alone, and the effect of Zr addition tends not to be sufficiently obtained.
When it exceeds, the influence of Zr having a low reflectance becomes strong, and it tends that the predetermined reflectance cannot be obtained. M for Al
The addition amount of o is preferably 0.02 to 40 atom%,
If it is less than 0.02 atom%, the corrosion resistance is not so different from that of Al alone, and there is a tendency that the effect of adding Mo is not sufficiently obtained, and if it exceeds 40 atom%, M having a low reflectance is obtained.
There is a tendency that the influence of o becomes strong and a predetermined reflectance cannot be obtained.

When both Zr and Mo are added to Al, the composition ratio of Zr and Mo is preferably 30: 1 to 1:20, and if it is out of this range, the corrosion resistance due to the synergistic effect of Zr and Mo is obtained. There is a tendency that no improvement can be obtained.

[0014]

According to the present invention, when aluminum, zirconium and / or molybdenum or the like is used as a target for sputtering, Ar and 20a are contained in the sputtering chamber.
By setting a mixed gas atmosphere of N ₂ of tom% or less, active Al can be partially stabilized as a nitride. Therefore, when sputtering is performed, it is possible to reduce the generation of harmful gas components that become impurities in this atmosphere. When the mixed gas atmosphere contains few impurities, the generation of pinholes and oxide films in the obtained reflection layer is reduced, and it is considered possible to form a high-quality reflection film.

Since this reflective film contains Zr and / or Mo instead of Al alone, the crystal grains of Al become fine and become a dense film. Therefore, deterioration does not occur even when recording and reproduction are repeated, and reliability is improved. Also,
Zr and Mo are effective in improving the corrosion resistance of Al, and A
It is possible to prevent the oxidative deterioration of l.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram schematically showing an example of the layer structure of a phase change optical disc to which the present invention can be applied. As shown in FIG. 1, a phase change optical disc to which the present invention is applicable has an optical disc substrate 6 on which a protective layer 2, a recording layer 1, a protective layer 3, a reflective layer 4, and a protective layer 5 are laminated. Have a configuration. This layer structure is an example in the case of a single plate, and it is also possible to bond two optical disks of this single plate with the surface having the recording layer 1 inside so as to form an optical disk for double-sided use. In addition, the protective layer 2, the protective layer 3, and the protective layer 5 can be omitted depending on the application.

The optical disk substrate 6 is made of a material that is transparent and has little change over time, such as polymethylmethacrylate (PMM).
It is made of acrylic resin such as A), polycarbonate resin, epoxy resin, styrene resin, or glass. On the substrate 6, continuous grooves, sample servo marks, free format marks, etc. are formed according to the recording format.

The recording layer 1 is at least Te, Sb, Ge.
And In as a main component, three or more selected from In and In are formed of a phase change material whose optical constant is changed by imparting thermal energy by a light beam. Examples of such phase change materials include GeSbTe-based, InSbTe-based, GeT
A ternary material such as an eIn-based material can be used. These materials whose optical characteristics change can be formed by a vacuum vapor deposition method, a sputtering method, or the like. The thickness of the recording layer 1 is preferably in the range of several nm to several μm for practical use.

The protective layers 2 and 3 are arranged so as to sandwich the recording layer 1, and the recording layer 1 is irradiated with a recording beam to
It has the role of preventing scattering and making holes. It also has a role of controlling heat diffusion of heating and cooling of the recording layer at the time of recording.

The protective layers 2 and 3 are made of Si0 ₂ , Si0,
_{AlN, Al 2 O 3, Zr0} 2, ZrO 2, Ta
_{It is made of 2} O ₃ , ZnS, Si, Ge or a mixed film thereof, and is formed by a vacuum deposition method, a sputtering method or the like. The thickness of the protective layers 2 and 3 is practically several nm to several μm.
Is preferred.

The reflective layer 4 has the effect of optically enhancing the optical change of the recording layer to increase the reproduction signal and the effect of cooling the recording layer. In the present invention, in particular, this reflective layer 4
And a material obtained by adding at least zirconium (Zr) or molybdenum (Mo) to aluminum (Al) is used, and when the reflective layer 4 is formed by the sputtering method, A
The target, which is a raw material of the reflective layer material, is sputtered in a mixed gas atmosphere of r and N ₂ of ₂₀ atom% or less. The thickness of the reflective layer is preferably several nm to several μm for practical use.

The protective layer 5 is provided to prevent scratches and dust when handling the phase change optical disk, and is usually made of an ultraviolet curable resin or the like. The protective layer 5 is formed, for example, by coating an ultraviolet curable resin on the surface of the reflective layer 4 by a spin coating method and irradiating it with ultraviolet rays to cure it. The thickness of the protective layer 5 is practically preferably in the range of several μm to several hundreds of μm.

In particular, in the present invention, it is desirable that the layer structure has a rapid cooling structure, and it is desirable that the protective layer 2 or the protective layer 3 is made of a material having a large thermal conductivity. Further, it is preferable that the material that changes the optical characteristics of the recording layer 1 is also a material that easily becomes amorphous. Further, it is also effective to reduce the thickness of the recording layer 1 and the thickness of the protective layer 3 on the reflective layer 4 side.

Furthermore, in order to obtain a large signal, the amount of optical change of the material whose optical characteristics change must be large, and high speed erasing must be possible in order to perform the overwrite operation. As such a material, a material containing at least three or more selected from the group consisting of Te, Sb, Ge and In as a main component is effective. For example, G
At least ternary materials such as eSbTe system, InSbTe system, and GeTeIn system can be used.

Here, Ge-Sb-T is used as the recording layer 1.
Using an e-based material, Al-4 atom% Z as the reflective layer 4
ZnS-20mo is used as the protective layers 2 and 3 using an r alloy film.
A 1% SiO 2 mixed film was used, a UV cured film was used as the protective layer 5, and a PC (polycarbonate) substrate was used as the optical disc substrate 6. An example of a method of manufacturing the information recording medium according to this embodiment will be described below with reference to FIGS.

FIG. 2 is a vertical sectional view showing a schematic structure of a sputtering apparatus used for manufacturing the information recording medium of this embodiment, and FIG. 3 is a transverse sectional view thereof. In the figure, 10 indicates a vacuum container, and this vacuum container 10 has a gas introduction port 11 and a gas exhaust port 12 on the bottom surface thereof.
The gas discharge port 12 is connected to the exhaust device 13,
The exhaust device 13 exhausts the inside of the vacuum container 10 through the exhaust port 12. Further, the gas introduction port 11 is connected to an argon gas cylinder 14, and this cylinder 14
Argon gas as a sputtering gas is introduced into the vacuum container 10 through the gas introduction port 11.

Although not shown, a gas introduction port for nitrogen gas and a nitrogen gas cylinder are provided as in the case of argon gas, and nitrogen gas is introduced through this port when the reflective layer is formed.

A disk-shaped rotating base 15 for supporting the substrate is disposed in the upper part of the vacuum container 10 with its surface horizontal, and the substrate 6 is supported on the lower surface thereof and rotated by a motor (not shown). It is supposed to be done. Further, in the vicinity of the bottom of the vacuum container 10, so as to face the base 15,
Sputtering source 21 made of Ge—Sb—Te based material for recording layer 1 constituting each layer, Zn for protective layers 2 and 3
Sputtering source 22 made of S-20 mol% SiO2 mixed film, and Al-3a for the reflective layer 4 according to the present invention.
A sputtering source 23 made of a tom% Zr alloy film is provided, and a high-frequency power source (not shown) is connected to each sputtering source. These sputtering sources 2
Monitor devices 24,
25 and 26 are provided, and the amount of power supplied to each sputtering source is adjusted so that the amount of sputtering from each sputtering source is monitored by these monitoring devices and the recording layer has a predetermined composition. .. In such a sputtering apparatus, first, the inside of the vacuum container 10 is evacuated by the evacuation apparatus to, for example, a unit of 1 to 1 Torr.

Next, while introducing argon gas into the container 10 through the gas introduction port 11, the exhaust amount of the exhaust device 13 is adjusted to maintain the inside of the vacuum container 10 in a predetermined argon gas atmosphere. In this state, while rotating the substrate 6,
A predetermined electric power is applied to each sputtering source in the order of layer structure for a predetermined time. As a result, a predetermined layer structure can be formed on the substrate 6.

In the present invention, particularly when forming the reflective layer, both the gas introduction port of argon gas and the gas introduction port of nitrogen gas are opened to adjust the gas flow rate so as to obtain a predetermined mixing ratio. Further, a mixed gas cylinder of argon and nitrogen having a predetermined mixing ratio may be prepared in advance, and the mixed gas may be introduced from the gas introduction port. [Experimental Example] Using the above-described sputtering apparatus, first, the inside of the vacuum container 10 was, for example, 8 Torr per million by an exhaust device.
Exhausted to. Next, argon gas and nitrogen gas were introduced so as to obtain a predetermined mixing ratio, and the inside of the vacuum container was heated to 3/1000 to
rr.

Further, the gas mixture ratio was changed in sequence, and Al-3 atom% Zr, respectively, were used as sputtering sources.
Al-2 atom% Mo, Al-2 atom%, Zr-
In the case of using the 1 atom% Mo alloy, it was examined whether or not the Al alloy film was formed by performing the sputtering. The electric power used was 60 to 150 W. The results are shown in Table 1.

[0033]

[Table 1] State of alloy film Nitrogen amount Al-Zr Al-Mo Al-Mo-Zr [atom%] None Not formed Not formed Not formed 5.0 Reflective film Reflective film Reflective film 10.0 Reflective film Reflective Film Reflective film 15.0 Reflective film Reflective film Reflective film 20.0 Reflective film Reflective film Reflective film 25.0 Semi-transparent film Semi-transparent film Semi-transparent film 30.0 Semi-transparent film Semi-transparent film Semi-transparent film From the above experimental results As is clear, Al as the reflection layer
In order to form the alloy film, it is effective that the amount of nitrogen mixed with the argon gas is 20% or less. On the other hand, when the amount of nitrogen mixed was 25% or more, the Al alloy film became a semitransparent film and was not suitable as a reflective layer. Further, when the nitrogen gas was not mixed, the Al alloy film was not formed.

The reflection film thus obtained did not have pinholes, incorporation of impurities, formation of oxide film, etc., and showed a sufficient optical reflectance. Further, when the information recording medium having this reflective film formed thereon was used as a phase change optical disc, the corrosion resistance, recording / reproducing and repetitive characteristics were good.

Although the embodiments of the phase change optical disk have been described above, the present invention is not limited to this, and information recording using a reflective layer such as an optical disk, an optical card, an optical tape used for recording and reproducing information. It can be applied to a method of manufacturing a medium.

[0036]

As described above, according to the method of the present invention, when the reflective layer made of a material containing aluminum (Al) and at least zirconium or molybdenum is formed on the substrate by the sputtering method, By setting the atmosphere to be a mixed atmosphere of argon and 20 atom% of nitrogen, a high-quality Al alloy reflective film having an optical sufficient reflectance can be obtained. In addition, the information recording medium having the reflection film thus obtained is excellent in corrosion resistance, recording / reproducing and repetitive characteristics.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a cross-sectional view of an example of a phase change optical disc recording medium according to the present invention.

FIG. 2 is a vertical sectional view showing a schematic configuration of an example of a sputtering apparatus used in the present invention.

3 is a cross-sectional view of the device shown in FIG.

[Explanation of symbols]

1 ... recording layer, 2 ... protective layer, 3 ... protective layer, 4 ... reflective layer, 5
... Protective layer, 6 ... Optical disc substrate, 10 ... Vacuum container, 11
... Gas introduction port, 12 ... Gas exhaust port, 13 ... Exhaust device, 14 ... Argon gas cylinder, 15 ... Rotation base, 2
1 ... Sputtering source, 22 ... Sputtering source, 23
... Sputtering source, 24 ... Monitor device, 25 ... Monitor device, 26 ... Monitor device.

Claims (1)

[Claims] 1. At least one selected from the group consisting of aluminum (Al), zirconium (Zr), and molybdenum (Mo) under a condition that the sputtering chamber is in a mixed gas atmosphere of Ar and N _{2 of 20} atom% or less. A method of manufacturing an information recording medium, comprising the step of forming a reflective layer on a substrate by performing sputtering using one kind of target as a target.