JPH035929A - Optical recording medium and its production - Google Patents

Abstract

PURPOSE:To improve performances of the medium and durability by constituting a transparent dielectric layer of amorphous tantalum oxynitride. CONSTITUTION:An amorphous tantalum oxynitride layer is formed as a transparent dielectric layer. Since amorphous tantalum oxynitride does not scatter laser light, the noise level can be reduced. The Ta oxynitride layer has lower inner stress, 1/2 - 1/5 of that of Ta oxide, and shows no crack or peeling in an environmental test at high temp. and high humidity. Moreover, the layer is almost free from pin holes. Thus, recording/reproducing property and durability of the magneto-optical recording medium can be largely improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to an optical recording medium on which information is recorded, reproduced, erased, etc. using light such as a laser. More specifically, the present invention relates to an optical recording medium having a transparent dielectric layer as a protective layer and/or an optical interference layer.

[Prior Art] Various studies are being conducted on optical recording media as high-density, large-capacity information recording media. In particular, rewritable information on magneto-optical recording media has a wide range of applications, and various materials and systems have been announced, and their practical application is eagerly awaited.

As the above-mentioned magneto-optical recording material, for example, JP-A-52-3
TbFe described in Publication No. 1703, JP-A-58-7374
There are already many proposals such as TbFeCo and DyFeCo described in Publication No. 6. However, in order to put these magneto-optical recording media into practical use, it is said that further improvements in recording/reproducing characteristics and durability are required. As a solution to this problem, a transparent dielectric layer is provided as an optical interference layer and a protective layer to improve the Kerr rotation angle by utilizing the optical interference effect, that is, multiple reflections of light, and at the same time to improve the Kerr rotation angle from the substrate side to the recording layer. It has been proposed to prevent the diffusion of gases that can cause deterioration. Such transparent dielectric layers include Sl,
Nitride of metals such as N4, AIN, ZnS, MgF2,
It is said that it is preferable to use sulfide, fluoride, or the like.

By the way, when we examined 513N4, AIN, etc., which are said to have excellent environmental resistance, we found that
The film forming speed is slow, and the distortion in the film is large.
In particular, when a multilayer film is formed on a plastic substrate, environmental tests have revealed that there are problems with peeling along the groups, and there are problems with durability in addition to oxidation resistance. Furthermore, since the refractive index of both cases is about 2.0, the limit for improving the Kerr rotation angle is about 0.5 to 0.7°C even if multiple reflections of light are used. However, there are also problems that cannot be met with various specifications. Therefore, from the standpoint of practical use, further improvements are desired in both of these points, particularly in terms of improved Kerr rotation angle and improved durability.

[Object of the Invention] The present invention was made in view of the current situation, and an object of the present invention is to provide an optical recording medium with high medium performance and good durability by improving the transparent dielectric layer. Specifically, by increasing the refractive index of the transparent dielectric layer of the recording medium, the optical interference effect is increased, and for example, in the case of a magneto-optical recording medium, the Kerr rotation angle is increased to improve the medium performance. The primary purpose is to In addition, by making the transparent dielectric layer have low internal stress and good adhesion, it particularly prevents cracking and peeling of the medium, and at the same time suppresses the occurrence of defects such as pinholes and improves the durability of the entire medium. The second purpose is to encourage others.

[Composition and operation of the invention] The above objects are achieved by the invention as follows.

That is, the present invention provides an optical recording medium having a transparent dielectric layer as a protective layer and/or an optical interference layer, wherein the transparent dielectric layer is made of amorphous tantalum (Ta) nitoxide. It is a recording medium.

The invention described above was made as follows. In other words, with the aim of improving the Kerr rotation angle in magneto-optical recording media, we have considered applying Ta205, a Ta oxide known to have a high refractive index, to the transparent dielectric layer, but due to high internal stress, it is not durable. In the high temperature, high humidity environmental resistance test for evaluating the product's properties, cracks and peeling occurred, and many pinholes were generated, indicating that the product lacked durability. Therefore, in order to solve this problem, we investigated how to improve the properties of the conventional Ta oxide described above, and found that Ta nitride oxide, which is made of nitrided and/or oxidized Ta obtained by adding nitrogen, is surprisingly In particular, it was found to be amorphous. Conventional Ta oxide is crystalline, so when recording and reproducing signals, laser light is scattered by crystal grain boundaries, increasing the noise level, but the Ta nitride according to the present invention It was found that because it is amorphous, there is no scattering of laser light, which reduces the noise level. In addition, Ta nitride is
Compared to conventional Ta oxide, the internal stress can be reduced to 172 to 115, which reduces cracking and cracking in high temperature and high humidity environment resistance tests.
It was found that no peeling occurred and almost no pinholes were generated. Furthermore, when we measured the moisture permeability, we found that T
a In nitride oxide, 10-'g -mrn/rrf
-day, which is a low value that cannot be obtained with conventional transparent dielectric materials such as 513N4 and AIN. This is effective in preventing deterioration of the recording layer due to gases such as oxygen and moisture entering from the outside.

Moreover, the refractive index of this Ta nitride has a small dependence on nitrogen content and has a refractive index of 2.
It was found that high values of 2 to 2,3 were obtained. However, if the amount of nitrogen is small, the film will turn brown, so
Absorption of laser light occurs when recording and reproducing signals. In order to avoid this, it is preferable to set the nitrogen content to at least lat% or more. On the other hand, if the amount of nitrogen is large, there will be no problem with the refractive index or transparency of the film, but the adhesion to the transparent substrate, especially the transparent polymer substrate, will decrease, resulting in cracks and cracks in high temperature/high temperature environment resistance tests. Peeling is likely to occur. Therefore, the nitrogen content is preferably 45 at% or less. In order to further improve the adhesion with the transparent substrate, it has been found that it is effective to further include In and/or Sn in the above-mentioned Ta nitride.

In this case, it has been found that it is sufficient for the content of In and/or Sn to be at least lat% or more in order to improve adhesion. By the way, this In and SO are contained in the Ta nitride oxide in the form of In and/or S[1 nitride oxide, like Ta, but the refractive index of this In and So oxide is 2.
．． Since the degree of oxidation is as small as 0, adding a large amount of these elements to Ta nitride oxide lowers the refractive index of the film as a whole. If you want to obtain a large optical interference effect as a recording medium, specifically the effect of improving the Kerr rotation angle in magneto-optical recording and the effect of confining laser light, the refractive index of the transparent dielectric film should be 2.
．． It is said that 0 or more, more preferably 2.1 or more is required, and when used as such an optical interference layer, In or /
and Sn content is 25 at% or less, more preferably 1
It is 5 at% or less.

In addition, the above-mentioned present invention is simple or! The Ta, In, and Ta nitrides added with D and/or Sn are
It goes without saying that elements other than Sn, O, and N may also be included on the order of impurities.

As a method for producing the Ta nitride oxide film of the present invention, various thin film forming methods can be applied, such as a known vacuum evaporation method, a PVD method such as a sputtering method, or a CVD method. However, in order to obtain sufficient durability as an optical recording medium without causing peeling in a high-temperature high-temperature environment resistance test, it is preferable to manufacture the optical recording medium under conditions where the adhesion to the polymer substrate is particularly high. For this purpose, a sputtering method is preferred. Among these, the reactive sputtering method using a Ta oxide target and a mixed gas of Ar and core is preferable from the viewpoint of stable operation and productivity since abnormal discharge is less likely to occur.

By the way, as mentioned above, the optical recording medium of the present invention uses the Ta nitoxide as a protective layer and/or an optical interference layer,
It is clear from the spirit of the present invention that other configurations are not particularly limited. For example, it can be applied to various known optical recording media such as a light reflective recording layer, a phase change optical recording layer, and a magneto-optical recording layer.

However, since the above-mentioned characteristics of the Ta nitride of the present invention, particularly a large optical interference effect and good resistance to moisture permeation, can be obtained, it can be particularly advantageously applied to magneto-optical recording media. Incidentally, as the magneto-optical recording medium, the following known ones can be mentioned.

In other words, the magneto-optical recording layer is one that can be recorded and reproduced by the magneto-optical effect, specifically, it has an easy magnetization direction perpendicular to the film surface, and can be created based on the magneto-optical effect by creating arbitrary reversal magnetic domains. Any magnetic metal thin film capable of recording and reproducing information may be used, such as TbFe, TbFeCo,
GdTbFe, GdFeCo, NdDyFeCo,
NdDyTbFeCo, NdFe, PrFe, C
Various known materials can be used, such as an amorphous alloy film of a rare earth element such as eFe and a transition metal element, or a garnet film. In addition, two or more of these magnetic metal thin films and/or
Alternatively, the present invention can also be applied to a recording layer having a multilayer structure in which two or more thin films having different compositions of even one type of constituent element are laminated so that the transition metal elements are in an exchange-coupled state.

In particular, when a material with a large Kerr rotation angle is used for the one provided closer to the substrate among the plurality of laminated magnetic metal thin films, that is, the signal successive layer, the Ta nitride of the present invention The optical interference effect due to the large refractive index provides a more significant effect in improving the Kerr rotation angle of the medium. Furthermore, the Ta nitride oxide of the present invention is particularly effective in terms of durability for recording layers made of easily oxidized materials such as the above-mentioned rare earth/transition metal alloys due to its moisture permeation resistance and the like.

As the material for the transparent substrate, polymer resins such as polycarbonate resin, acrylic resin, epoxy resin, 4-methylpentene resin, or copolymers thereof, or glass can be used. Among them, mechanical strength, weather resistance, heat resistance,
Polycarbonate resin is preferred in terms of moisture permeability.

By the way, as mentioned above, the Ta nitride of the present invention has excellent properties in terms of adhesion with the substrate, internal stress of the film, moisture permeability, etc., and it is suitable for use with transparent polymer substrates such as polycarbonate resin. This is particularly effective for magneto-optical recording media. In this structure, between the composite oxide film and the magneto-optical recording film, Ag, Cu, Au, Al, Si, T
From the viewpoint of oxidation resistance and moisture permeability, it is preferable to provide a metal thin film using at least one element selected from the group consisting of Cr, Ta, Zr, Re, and Nb. The thickness of this metal thin film must be 50 Å or less from the recording/reproducing surface, and preferably 20 Å or less from the viewpoint of increasing the CNR of the medium.

As described above, the present invention provides a magneto-optical recording medium having the above-mentioned transparent dielectric layer made of Ta nitride, the above-mentioned transparent metal protective layer, and magneto-optical recording layer in this order on a polymer substrate. The effect is remarkable.

The present invention is based on the above-described magneto-optical recording medium, and also includes a backside protective layer or a transparent dielectric layer on the side opposite to the substrate of the magneto-optical recording layer, which also serves as protection with or without intervening, as is known in the art. It can be applied to all configurations including a configuration in which a reflective layer is provided, and furthermore, a configuration in which a flat plate or the same medium is bonded to a medium of these configurations.

The transparent dielectric material used for the back protective layer and/or the interference layer of the reflective layer is suitable for oxygen and H
In order to prevent the intrusion of 2O, materials with few cracks or pinholes are preferable, such as AIN, MgF2, znS, CeF3,
AlF3 ・3NaF, SI3 N4, SIQ,
Nitride such as 5i02, Zr2O3, In203.5n02, fluoride, oxide, or a mixture thereof can be used.

In particular, the aforementioned Ta nitride of the present invention is suitable as such a protective layer and/or interference layer because it does not cause peeling or cracking in a durability test, and the present invention also includes such a structure. . In addition, when using a metal protective layer as the back protective layer and/or reflective layer, Ag, Cu
, Au, Al, Si, Ti, Or, Ta,
Metal films made of alloys of these Zr, Re, Nb, etc. can be applied, but in order to reduce heat diffusion to the laser beam spot during recording, materials with low thermal conductivity,
That is, a metal film made of Ti, Cr, Ta, Re, or an alloy thereof is preferable, and when it also serves as a reflective layer, Ag, C is preferably used so as not to impair the function as a reflective film.
Ti, C'', T in u, Au, AI or their alloys.
A metal film containing one or more metals among a, zr, and Re is particularly preferred. The above-described inorganic protective layer including the reflective layer and its interference layer can be produced by a known PVD method such as a vacuum evaporation method or a sputtering method.

Furthermore, an organic material protective layer can be used as the back surface protective layer. As such an organic substance protective layer, various known photosensitive resins can be used, and it can be formed by a coating method or the like.

Note that it is preferable to use the organic protective layer in combination with the above-mentioned inorganic protective layer so that the inorganic protective layer is in contact with the recording layer. The back surface protective layer may be a combination of the above protective layers. Note that the back surface protective layer is preferably provided so as to cover at least the side surfaces of the recording layer.

It is clear from the characteristics that the above-mentioned protective layers of each company can be applied to optical recording media other than magneto-optical recording media, such as phase change type optical recording media.

The effects of the present invention described above are as follows.

As mentioned above, in a magneto-optical disk with a typical configuration in which a transparent plastic substrate is used and a transparent dielectric layer is provided between the substrate and the magneto-optical recording layer in order to increase the Kerr rotation angle due to film surface reflection, the dielectric Typical conventional film is Sin
, AIN, 5t3N4.5i02, etc., the Kerr rotation angle of these media is 0.5 to 0.7°, and the Kerr rotation angle is still sufficiently improved due to the effect of multiple reflection of light in the dielectric layer. It can not be said. This is considered to be because the refractive index of each of the dielectrics described above is as small as 1.9 to 2.0 degrees.

Furthermore, when magneto-optical disks using these conventional dielectrics were subjected to durability tests at high temperatures and/or heat cycles, it was observed that cracks appeared in the disks and the magneto-optical properties rapidly deteriorated.

This is mainly due to peeling of the dielectric film at the interface of the plastic substrate.

On the other hand, in the magneto-optical disk of the above-described typical configuration of the present invention in which the above-mentioned Ta nitride is used for the transparent dielectric layer, the Kerr rotation angle is 018 to 1. Oo, and at the same time, no peeling or cracking occurs due to deterioration at the interface with the plastic substrate in the durability test mentioned above.

This is thought to be due to the fact that the Ta nitride oxide has a large refractive index of 2.1 to 2.3, and also has great affinity with organic polymer resin substrates such as polycarbonate substrates. As described above, the present invention not only improves media performance but also improves long-term stability under normal environments and durability against heat cycles and heat shock.

Furthermore, in conventional crystalline dielectric films, scattering of light and disturbance of recorded bits due to crystal grain boundaries are the causes of noise that occurs during recording, reproduction, and erasing of media. Nitoxide is amorphous, so there is almost no such scattering or disturbance, and it has been found that noise during recording and reproduction can be reduced compared to the conventional magneto-optical disk described above.

It is clear that the effects of the present invention described above are not limited to magneto-optical recording media, but can be similarly achieved in known optical recording media such as phase change type and reflective type. Therefore, the present invention is widely applicable to optical recording media. As described above, the present invention greatly contributes to improving the characteristics of optical recording media, especially magneto-optical recording media, including their durability.

Hereinafter, the present invention will be explained using examples.

[Examples 1 to 13, Teaching Examples 1 to 3] A transparent dielectric film was created on a substrate in the following manner, and its characteristics were evaluated.

A disc with a diameter of 130mm and a thickness of 1.2mm, 1.6μ
Polycarbonate resin (P
C) disk substrate, Si wafer (10mm x 10
mm square), slide glass (length 76 mm x width 2
6mm x 1mm thick) and thin glass (18mm diameter x 0, 1ma+ disk) using a 3-target high frequency magnetron sputtering system R (5PF-4 made by ANELVA).
30H type) in a vacuum chamber, 4 x 10'-'T
Exhaust until it reaches orr.

Next, Ar/N2 mixed gas was introduced into the vacuum chamber, and the pressure was 5i.
The Ar/N2 gas flow rate was adjusted to Torr.

As a target, a Ta2O sintered body with a diameter of 100 mm and a thickness of 5 mm is used, and if necessary,
[Arrange an appropriate number of 1203 or/and 5n02 oxide sintered chips (discs with a diameter of 5 mm and a thickness of inm). Discharge power ioow, discharge frequency 13.56M)I
By performing high-frequency sputtering in Z and adjusting the N2 partial pressure in the A/N2 mixed gas, a Ta nitride oxide film having the composition shown in the film composition column of Table 1 can be formed by approximately 100%
0 people deposited and obtained samples of each example in Table 1.

First, using a sample deposited on a Si wafer, the refractive index of the thin film with respect to light with a wavelength of 830 nni was determined.

As a measuring device, an automatic ellipsometer DIIA-OLW manufactured by Shotoku Kogaku Kogyo Co., Ltd. was used. The results are shown in the refractive index column of Table 1.

Next, the internal stress of the thin film was determined using the sample deposited on the thin glass. TENCOftINST for measurement
Stylus type surface roughness meter alpha-st manufactured by RUMENTS
Using EP200, the amount of warpage was measured when a length of 2 mm was scanned with a stylus, and the internal stress σ was determined. The results are shown in the internal stress column of Table 1.

In addition, the crystalline state was measured using a sample deposited on a glass slide. For measurement, manufactured by Rigaku Denki, s force x
as-folding device) 11G) IPQWERtlNIT &lO
[11EI.

D-3F was used. The results are shown in the column of crystalline state in Table 1.

Furthermore, using a sample deposited on a PC disk substrate, the adhesion between the thin film and the PC substrate was measured. A cellophane adhesive tape JIS Z1522 manufactured by Sekisui Co., Ltd. was attached to the surface of the thin film, and when the cellophane tape was peeled off in a direction parallel to the substrate surface, the state of peeling of the thin film was observed visually and with a microscope.

The results are shown in the column of adhesion in Table 1. The meanings of the symbols used in this column are as follows.

◎: Good adhesion, no peeling at all ○: Peeling of about 2 to 3 groups was observed by microscopic observation.

×: The film is completely peeled off.For comparison, conventional examples of Ta205, ZnS, and Human I
A thin N film was prepared and evaluated as follows.

In exactly the same manner as in Examples 1 to 13, a PC disk board,
Prepare the Sl wafer, slide glass, and thin glass substrates, fix them in a vacuum chamber of a three-target high-frequency magnetron sputtering device (manufactured by ANELVA, model 5PF-43011), and evacuate until the temperature reaches 4 X IQ 'Torr. do.

Then, Ta205, ZnS, A
Using each sintered body of IN, the sputtering gas was A r / 02,
Example 1 except that pure Ar (5N) and Ar/N2 were used.
Samples of the comparative examples shown in Table 1 were prepared in exactly the same manner as in 13 to 13, and the refractive index, internal stress σ, and crystal state were measured. The results are shown in Table 1.

From the above Examples 1 to 13 and Comparative Examples 1 to 3, the internal stress of Ta nitride according to the present invention can be reduced to 1/2 to 115 by adding nitrogen, and regardless of the N content, It was found that a high refractive index of 2.05 to 2.35 can be obtained over a wide range. This means that in manufacturing, there is a wide margin in the refractive index with respect to changes in the N2 partial pressure in the sputtering gas.

It is understood that when the Ta content is 1 oat% or more, a high refractive index of 2.1 or more can be obtained. Moreover, it was surprisingly found that the Ta nitride oxide according to the present invention is in an amorphous state. Therefore, it is thought to have the effect of reducing media noise, such as by reducing the scattering of laser light by crystal grain boundaries during recording and reproducing and by minimizing disturbances in the bit shape due to non-uniform heat conduction during bit formation. Regarding the adhesion between the thin film and the PC board, even if Ta nitride is used, conventional Ta2
05. The adhesion can be improved compared to ZnS and AIN, but to further improve the adhesion, it is necessary to use In or/and Sn.
It is preferable to use Ta nitride containing Ta.

From the above points, it is considered that if the Ta nitride according to the present invention is used as a dielectric layer of a magneto-optical recording medium, the laser light confinement effect will be improved, and recording sensitivity and CNH will be improved. In addition, because the internal stress is reduced, it can be expected to have the effect of suppressing the occurrence of defects such as peeling and cracking during high temperature and high temperature environment resistance tests.

The Ta nitride of Examples 1 to 13 above is used as an optical interference layer or/
A magneto-optical disk with a protective layer and a protective layer was prepared, and the effects of the present invention were confirmed.

Table 1 [Examples 14 to 26, Comparative Examples 4 to 6] Magneto-optical disks having the configuration shown in FIG. 1 were prepared and evaluated in the following manner. In the figure, 1 is a substrate, 2 is a dielectric,
3 is a transparent metal thin film layer, 4 is a recording layer, and 5 is a back surface protective layer.

A disk with a diameter of 130mm and a thickness of 1.2oon, 1.6
Polycarbonate resin with groups of μm pitch (
A three-target high-frequency magnetron sputtering device (5PF-430 manufactured by ANELVA (II)
Fixed in a vacuum chamber of 4 X 1O-7 Torr
Exhaust until Note that during film formation, the substrate 1
Rotated at 5 rpm.

Next, in the same manner as in Examples 1 to 13 described above, a transparent dielectric layer 2 made of Ta nitride having the composition shown in each Example shown in Table 2 was formed. In other words, the target has a diameter of 100 mm.
Using a disk-shaped Ta205 sintered body with a thickness of 5 mm, a required number of 1n203 and/or 3002 chips were appropriately arranged on the target so that the composition was as shown in the film composition column of Table 2. Then, an Ar/N2 mixed gas was introduced into the vacuum chamber, and the Ar
/ Adjusted the flow rate of N2 mixed gas. Then discharge power 1
High frequency sputtering was performed at 00 W and a discharge frequency of 13.56 MHz to deposit about 700 nitride oxide films having the compositions shown in each example in Table 2 as the dielectric layer 2.

Next, as the transparent metal thin film layer 3, the target was changed to one in which Re chips (5X5X1ffim) were arranged on the disk of A1, and the same discharge as above was performed except that the sputtering gas was changed to pure Ar (5N) rather than Ar/N2. A with conditions
Deposit about 15 19oRe+o alloy films (the suffix indicates the composition (atomic %)).

Next, the target is TbwsFea as the magneto-optical recording layer 4.
9COa alloy (the suffix indicates the composition (atomic %)) was replaced with a Tb23F disk under the same discharge conditions as the AlRe alloy film.
An e6qCOa alloy film was deposited at a thickness of about 400A.

Furthermore, the target was returned to one in which Re chips were placed on Al to serve as a reflective layer as the back surface protective layer 5, and approximately 500 A19oReto alloy films were deposited under the same discharge conditions as described above.

In the above order, magneto-optical disks (Examples 14 to 26) having the laminated structure shown in FIG. 1 with the same structure as the transparent dielectric layer made of Ta nitride having the composition of each example in Table 2 were prepared. Good value.

The measurement results of the Kerr rotation angle of this magneto-optical disk (laser wavelength λ: 633 nm) are shown in the Kerr rotation angle column of Table 2. Next, the CNR of this disk was measured.

For measurement, magneto-optical recording and reproducing device Kunakamichi 0MS-100 was used.
Using 0TypeI[i], the disc was rotated at 1800 rpm.
Recording, reproduction, and erasing were performed at a position with a radius of 30 mmH.

Signal reproduction was performed with a laser power of 1.2 mW.

The optimum laser power during recording was determined to be the value that maximizes the difference between the primary high frequency and secondary high frequency during signal reproduction. The signal frequency was set to 2, OMB2. The optimum laser power for each medium is shown in the column of recording power in Table 2. The magnetic field applied during recording and erasing is 5000e (Oersted).

The noise level indicates the absolute level based on 1mW.d
It was expressed in units of Bm.

When the surfaces of these disks were observed, no defects such as pinholes, peeling, or cracks were observed.

Next, these disks were left in a high-temperature, high-humidity atmosphere of 80° C. and 85XRII for 1000 hours. Thereafter, when the Kerr rotation angle, optimum laser power during recording, CNR, and noise level were measured, no changes were observed compared to the measurement results before leaving. In addition, pinholes and peeling on the media surface
No defects such as cracks were observed.

For comparison, the conventional Ta20
Example 1 except that 5, ZnS, and AIN were used as the dielectric layer
A magneto-optical recording medium having the structure shown in FIG. 1, which is exactly the same as that of Examples 4 to 26, was prepared and evaluated.

A disk with a diameter of 130 mm and a thickness of 1.2 mm, 1.6.
A polycarbonate resin (PC) disk substrate with czm pitch groups was fixed in exactly the same sputtering equipment as used in Examples 14-26 under exactly the same conditions.

For Ta205, 2nS, or AIN of the dielectric layer 2, a sintered body of Ta20q, ZnS, or AIN is used as a target, and the sputtering gas is A r /'02, pure Ar (5N) in the order of description for each target.
, Ar/N2 to a thickness of 700 mm, and the other layers were sputtered under exactly the same conditions as in Examples 14 to 26.
Magneto-optical disks (Comparative Examples 4 to 6) having the same configuration as Examples 14 to 26 were produced with IN.

Example 14- Regarding the obtained magneto-optical disk of comparative example
Similarly to No. 26, the Kerr rotation angle, recording power CNR, and noise level were measured. The results are shown in the column of comparative examples before standing in Table 2.

Further, when the disk surface was observed, no defects such as pinholes, peeling, cracks, etc. were observed.

Next, this magneto-optical disk was left in a high-temperature, high-humidity atmosphere at 80° C. and 85% RH for 1000 hours. After that, the car rotation angle and recording time! & Appropriate laser power, CNR, and noise level were measured. The results are shown in the column of comparative examples after standing in Table 2. It can be seen that the relative rotation angle, recording sensitivity, CNR, and noise level were all degraded before being left unused. In addition, pinholes were observed on the disk surface.

[Example 27] A magneto-optical disk having the configuration shown in FIG. 2 was prepared and evaluated as follows. In Figure 2, 1.2.4 is the first
As in the figure, 6 is a back dielectric layer that also serves as an interference layer of the back protection layer, and 7 is a metal layer that also serves as a reflective layer of the back protection layer.

A disk with a diameter of 130mm and a thickness of 1.2mm, 1.6a
Polycarbonate resin with groups of m pitch (p
The disk substrates of c) were fixed in exactly the same sputter setup as used in Examples 14-26 under exactly the same conditions.

First, a nitrogen-containing Ta oxide film was formed as the dielectric layer 2 in the following manner. A/N2 mixed gas was introduced and the flow rate of the A/N2 mixed gas was adjusted so that the pressure was 5 mTorr.The target was a diameter of 100 au.
A sintered target was used, which was a disc with a thickness of 5 am and had a composition of Ta271nt 07° (the subscript number is atomic %). High-frequency subinterning was performed at a discharge power of 100 W and a discharge frequency of 13.56 MHz, and Ta271 was formed as the dielectric layer 2.
Approximately 1,000 people deposited a nitride oxide film having a composition of nt 027N45 (subscript number is atomic %).

Next, the sputtering gas was changed from Ar/N2 to pure Ar (5
Instead of Nl, the target is Nd5DyxsTb.
Using an alloy target with a composition of a Fe6°C0t2 (subscript number is atomic%), sputtering was performed under the same discharge conditions as above, with the target replaced, to form the magneto-optical recording layer 4 shown in Fig. 2. , Nds DytsTb
A sPe6oCOx2 alloy film was deposited to a thickness of 200 nm.

The target is again T with the nitride oxide film of dielectric layer 2 formed.
Return to the sintered target of a271nt 072, and add Ta of the same nitride oxide as dielectric layer 2 under the same conditions as dielectric layer 2.
A back dielectric layer 5 made of 1nON was deposited at a thickness of about 500A.

Finally, place the target on Al with a Re chip (5mmφ
A19oRe was used as the metal layer 6 of the reflective layer under exactly the same conditions as the recording layer 4.
Approximately 500 xo films (subscript numbers are atomic %) were deposited to obtain a magneto-optical disk having the laminated structure shown in FIG. Regarding this disk, the Kerr rotation angle, recording power, CNR, and noise level were measured in the same manner as in Examples 14 to 26. The measurement results show that the Kerr rotation angle is 1.05 degrees, the recording power is 4.5 mW,
CNR is 54.7dB, noise level is -60.0d
It was Bm. Also, when I observed this disk surface, I found that
No defects such as pinholes, peeling, or cracks were observed.

Next, this disk was left in a high temperature, high humidity atmosphere of 80° C. and 85% RH for 1000 hours. When the Kerr rotation angle, the optimum laser power during recording, the CNR, and the noise level were measured after that, no change was observed compared to the measurement results before being left, as in Example 14-26. Furthermore, no defects such as pinholes, peeling, or cracks on the medium surface were observed.

[Example 28] A magneto-optical recording medium shown in FIG. 3 in which an exchange-coupled two-layer film was used as a magneto-optical recording layer was prepared and evaluated in the following manner. In Figure 3, 1.2.5 is the same as in Figure 1, and 4
a and 4b are exchange-coupled magneto-optical recording layers.

A disc with a diameter of 130mm and a thickness of 1.2mm, 1.6μ
Polycarbonate resin with a group of D pitch (P
The disk substrate 1 of Example C> was fixed in exactly the same sputtering apparatus as used in Examples 14 to 27 under exactly the same conditions.

First, a Ta nitoxide film was formed as the dielectric layer 2 in the following manner. Introduce the Ar/N2 mixed gas into the vacuum chamber and adjust the flow rate of the Ar/N2 mixed gas so that the pressure becomes 5 mTorr. Diameter 100 as a target
mm, 5mm thick disk, composition Ta271nt
A sintered target of o7° (subscript number is atomic %) was used.

High frequency sputtering was performed with IZ (discharge power 100W, discharge frequency 13.56M), and Taz7 was used as the dielectric layer 2.
Approximately 700 people deposited a nitride oxide film having a composition of 1nx027N45 (subscript numbers are atomic %).

Next, the sputtering gas was changed from Ar/N2 to pure A
r and set Gd2.5Fes6CO□ as the target.
o, Tb23Fe69C08 (subscript number is atomic%) alloy target, and Ti chip on Cu (5X5X1
The above-mentioned dielectric layer 2 was
Sputtering was performed under the same discharge conditions as above, replacing the target, and Gd+4FeqbC as shown in Fig.
First recording layer 4a made of o□0 alloy, Tb23F
The second recording layer 4b made of 69CO8 alloy and Cu
The back protective layer 5, which also serves as a reflective layer, made of 9sTi5 (subscript number is atomic%) was applied to 150 people, 250 people, and 250 people, respectively, around j.
It was deposited to a film thickness of 500. Here, the magneto-optical recording layer 4
a and 4b are in an exchange coupled state.

Similar to Examples 14 to 27, Kerr rotation angle, recording power, C
NR and noise level were measured. The measurement results are: Kerr rotation angle is 1.20 degrees, recording power is 4.7 mW, C
NR is 57.0 dB, noise level is -60.2d
It was Bm.

When the surface of the medium was observed, no defects such as pinholes, peeling, cracks, etc. By using a Ta nitride thin film containing / and Sn as a dielectric layer, improvements in Kerr rotation angle, recording sensitivity, CNR, and durability can be achieved as expected from its characteristics.
It was also found that a magneto-optical recording medium with reduced noise level can be realized. As shown in Examples 1 to 13, the Ta nitride increases the refractive index of the dielectric layer, thereby improving the optical interference effect, specifically the laser light confinement effect, and increasing the Kerr rotation angle. , recording sensitivity, CNR
It was confirmed that it is possible to improve the

In addition, the transparent dielectric layers of Examples 14 to 28 are those of Examples 1 to 28.
As shown in Fig. 13, it is in an amorphous state. Compared to films such as Ta205, zoS, and AIN in this slick crystal state, recording and
There is little disturbance in the bit shape due to scattering of laser light by crystal grain boundaries during reproduction and non-uniformity of heat conduction during bit formation, resulting in a reduction in noise level.

Furthermore, as shown in Examples 5 to 13, it was found that by further adding In and/or Sn to Ta nitride, the adhesion between the PC substrate and the dielectric film could be improved within the layer. . Furthermore, as shown in Examples 1 to 13, the Ta nitride film of Examples 14-28 has Ta205, z
Internal stress is reduced to 1/2 to 1/4 compared to nS and AIN. For these reasons, even when accelerated deterioration tests are performed under high temperature and high humidity conditions, there is no peeling or cracking due to internal stress in the film or lack of adhesion to the PC board, which has a significant effect on improving durability. I found out that it plays.

As described above, it is clear that the present invention greatly improves the recording/reproducing characteristics and durability of optical recording media, particularly magneto-optical recording media.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the laminated structure of the magneto-optical disks of Examples 14 to 26 and Comparative Examples 4 to 6, FIG. 2 is of Example 27, and FIG. 3 is of Example 28.

Claims (1)

[Claims] 1. In an optical recording medium having a transparent dielectric layer as a protective film and/or an optical interference layer, the transparent dielectric layer is made of amorphous tantalum (Ta) nitoxide. Characteristic optical recording media. 2. The optical recording medium according to claim 1, wherein the tantalum nitride further contains In and/or Sn. 3.Ag, Cu, Au, Al, Si, Ti, Cr, Ta
, Zr, Re, and Nb.
3. The optical recording medium according to claim 1, further comprising a metal film using a seed element as a protective layer and/or a reflective layer. 4. The nitrogen content of the tantalum nitride is 1 to 45 at.
%. The optical recording medium according to any one of claims 1 to 3. 5. The oxygen content of the tantalum nitride oxide is 27 to 71a
5. The optical recording medium according to claim 1, wherein the optical recording medium is t%. 6. In the method for manufacturing an optical recording medium according to any one of claims 1 to 5, the tantalum nitride layer is made of Ta.
or an oxide of Ta containing In and/or Sn as a target, and is formed by sputtering in a nitrogen atmosphere consisting of a reactive gas containing nitrogen in an inert gas. manufacturing method.