JP2528188B2 - Optical recording medium - Google Patents

Description

The present invention relates to an optical recording medium for recording / reproducing / erasing information by using light from a laser or the like. More specifically, it is suitable for magneto-optical recording in which a magneto-optical recording layer made of a metal thin film having a direction of easy magnetization perpendicular to the film surface is formed on a transparent substrate and information is recorded / reproduced by the magneto-optical effect. , An optical recording medium having excellent medium performance and environmental resistance.

[Prior Art] Among optical recording media, the magneto-optical recording medium has been partially put on the market as a rewritable information recording medium having high density and large capacity.

Many proposals have already been made for the recording layer of the above-described magneto-optical recording medium, such as TbFe described in JP-A-52-31703 and TbFeCo described in JP-A-58-73746. However, these materials have a Kerr rotation angle that is one of their magneto-optical properties.
Very small at 0.3 to 0.5 °,
There is a problem that the CNR (Carrier to Noise Ratio) is low. At the same time, most of these materials also have a problem in terms of durability that they are susceptible to corrosion such as oxidation. Therefore, in order to solve these problems, a transparent dielectric layer is provided as a light interference layer and a protective layer between the substrate and the recording layer to improve the Kerr rotation angle by utilizing the light interference effect, that is, the multiple reflection of light. At the same time as fogging, it has been proposed to prevent diffusion of gas such as oxygen from the substrate side. It is said that such a transparent dielectric layer is preferably formed of a nitride such as Si ₃ N ₄ , AlN, AlSiN, TiN, TaN, NbN, ZnS, a sulfide, or a composite thereof. .

By the way, when these materials were examined, especially when a multilayer film was formed on a plastic substrate, there was a problem that peeling along the groove occurred due to an environmental test,
It has been found that there is a problem with durability on a side different from oxidation resistance.

[Purpose of the Invention] As a solution to the present situation, the inventors of the present invention disclosed in Japanese Patent Application No. 63-313751 previously filed at least one of novel In (indium) and Sn (tin). A dielectric layer made of oxynitride is also disclosed in
In the specification of -328851, a dielectric layer composed of an oxide of at least one of In and Sn and (bismuth) Bi, and further made of a nitric oxide was proposed. These new transparent dielectric layers showed improved performance in durability as well as excellent optical properties.

However, in some commercially available magneto-optical recording media, there is a strong demand for long-term stable recording storage,
Further improvement in durability is required. Therefore, when the durability of the magneto-optical recording medium using the novel dielectric layer proposed by the inventors of the present invention was examined in an accelerated test under high temperature and high humidity described later, 1000 hours, which was a standard for practical use, was obtained. Can withstand, but more than 2000 hours is considered more preferable
It was found that the CNR was significantly reduced.

The present invention has been made to solve such a problem, and it is an object of the present invention to provide an optical recording medium which is stable for a long time and has good durability, using the above-mentioned novel transparent dielectric layer previously proposed by the present inventors. It is intended.

[Configuration and Function of the Invention] The above object is achieved by the present invention described below. That is, the present invention, in the optical recording medium having a transparent dielectric layer between the substrate and the recording layer, the transparent dielectric layer is laminated on the substrate, at least one of Ni or Ni oxide, Alternatively, a first layer made of at least one of In and Sn and Bi oxide or oxynitride, and a second layer made of a transparent dielectric material containing no oxygen, which is laminated on the recording layer side of the first layer. It is an optical recording medium characterized by the following.

The present invention described above has been made as follows. That is, for at least one of the above-mentioned In or Sn oxynitrides, further, at least one of In or Sn and the Bi nitriding oxides or oxides for a cause of a large decrease in the CNR of the magneto-optical recording medium using an oxide, It is considered that the cause is oxidation of the recording layer due to free oxygen existing at the interface between the oxide or the oxide and the recording layer or incompletely bonded oxygen in the oxide or the oxide. In order to make full use of the characteristics of the transparent oxide layer of nitric oxide or oxide, it is necessary to prevent the oxidation of the recording layer by providing a barrier layer for preventing deterioration of the recording layer due to oxygen from the nitric oxide or oxide. in, such _{materials, Si 3 N 4, AlN,} AlSiN, TiN, TaN, NbN, nitrides such as ZnS, a transparent dielectric layer containing no oxygen consisting of sulfides or their complexes and the like suitable Was considered to be.
From the above-mentioned point, the transparent dielectric layer is made into two layers, the substrate side is the above-mentioned nitride oxide or oxide, and the recording layer side is a transparent dielectric material containing no oxygen such as nitride or sulfide. It was possible to obtain an optical recording medium excellent in durability without cracking or peeling in the high temperature and high humidity environment resistance test and without lowering CNR.

Therefore, one of the transparent dielectrics forming the first layer of the present invention is the one disclosed in the above-mentioned Japanese Patent Application No. 63-313751, in which at least one oxide of In and Sn contains nitrogen. Nitrogen is an In and / or Sn nitrite, and nitrogen is In, S
It is considered that n is contained in various states such as nitride and oxynitride. As described in this specification, the internal stress that influences the warp of the medium is greatly reduced to a fraction or less as compared with the conventionally known oxide and nitride single films in this oxide film. . Moreover, the refractive index directly linked to the enhancement effect is ITO.
(Indium-Tin-Oxide) film and the like oxide film, the gas barrier property against water vapor is also improved. On the other hand, the adhesiveness is as good as the IT film and far superior to the nitrogen film such as AlSiN. The internal stress is obtained in a wide range of gas pressure during film formation, which is also advantageous in terms of stable production.

In addition, this In, Sn nitriding oxide may contain a part of fine crystals, but is mainly amorphous, which is more advantageous in terms of durability and homogenization of optical characteristics, and hence noise level. In this respect, all-amorphous ones are particularly preferable.

This effect has been confirmed even at a trace nitrogen content of 1 at% (atomic%) or less.
Basically, the nitrogen content of the nitrogen oxide of Sn and / or Sn is not particularly limited. However, as the nitrogen content increases, the adhesiveness to the polymer resin tends to decrease, and from this aspect,
The nitrogen content is preferably 40 at% or less. Also, internal stress,
From the viewpoint of refractive index, the nitrogen content is preferably 1 at% or more.

The nitrogen content includes all nitrogen contained in the film, and includes nitrogen contained in any form such as nitride.

In addition, the content of In, Sn of the above-described In or / and Sn nitriding oxide of the present invention is not particularly limited, and In, Sn alone, respectively, including both at the same time, but Sn increases Therefore, the Sn content is preferably 50 at% or less based on the total amount of In and Sn from the viewpoint of transparency.

From the viewpoint of further increasing the refractive index, it is preferable to add a transparent dielectric having a high refractive index. Examples of such transparent dielectrics include ZnS, Ta ₂ O ₅ , TiO ₂ , ZrO ₂ and Al ₂ O ₃ . The addition amount is selected according to the required refractive index.

Further, the other of the transparent dielectrics forming the first layer of the present invention is
The one disclosed in the above-mentioned Japanese Patent Application No. 63-328859,
It is an oxide obtained by adding Bi to In or / and Sn, and a nitrogen oxide obtained by adding nitrogen to this.

As disclosed in the specification, at least one of In and Sn and B
Oxides and iodide oxides with i are amorphous films, their internal stresses are smaller than those of the individual oxide films of In and Sn, and their refractive indices are wide at a high level of 2.0 or more depending on the added amount of Bi. In addition, it has excellent characteristics as a transparent dielectric layer of an optical recording medium in which the adhesiveness is similar to that of In or Sn oxide.

Furthermore, since the above-described conventional indium oxide, tin oxide or a mixture thereof has high electric conductivity, it has high thermal conductivity contributed by electrons, and during recording, due to thermal diffusion from a portion to be recorded, the bit of There is a drawback that the shape is disturbed. However, the addition of Bi described above has the effect that the electrical conductivity is lost, the thermal conductivity can be significantly reduced, and the disorder of the recording bit shape can be suppressed.

From the above-mentioned point, the oxides and oxynitrides are preferably amorphous ones which have no grain boundaries and are advantageous in terms of noise level, corrosion resistance, gas barrier properties, etc., but the Bi content is 1 at% or less. It has been confirmed that even a trace amount becomes amorphous,
When used as a mere protective layer, the content thereof is not particularly limited. However, in order to obtain a large optical interference effect, specifically, a Kerr rotation angle improving effect in magneto-optical recording and a laser light confining effect, it is said that a refractive index of 2.0 or more, more preferably 2.10 or more is required, When used as such an optical interference layer, the Bi content is 6 at% or more, and further 12a
t% or more is preferable. It should be noted that if these contents are contained, the thermal conductivity is also greatly reduced, and the disorder of the recording bit shape can be suppressed.

On the other hand, when the Bi content increases, the adhesive strength with the plastic substrate and the like decreases, and the durability of the medium as a whole decreases. On the other hand, if the Bi content is too high, the refractive index becomes too high, and the medium reflectance decreases, possibly lowering the detection sensitivity of the recording / reproducing apparatus. From this point, the Bi content is preferably 50 at% or less, more preferably 40 at% or less.

It should be noted that the above-mentioned Bi and nitrogen-containing oxynitrides have the effect of improving the refractive index, but when the nitrogen content increases, the above-mentioned adhesive strength tends to decrease. From this point, the nitrogen content is preferably in the range of 1 at% to 40 at%.

Needless to say, the above-mentioned nitriding oxides and oxides forming the first layer of the present invention may contain elements other than Bi, In, Sn, O, and N in the order of impurities.

As the method for producing the above-described In, Sn, and further Bi-containing nitriding oxides and oxide films forming the first layer of the present invention, known vacuum deposition methods, PVD methods such as sputtering methods, or CVD methods, etc. Various thin film forming methods can be applied. However, the optical recording medium is preferably manufactured under the condition that the adhesiveness to the plastic substrate is particularly large in order to prevent the peeling that occurs in the high temperature and high humidity environment test from occurring. For this purpose, the sputtering method is preferable. As the target used in the sputtering method, In, Sn, Bi metal or an alloy thereof, or InN, In ₂ O ₃ , SnN, SnO ₂ , ITO, BiN, Bi ₂ O ₃ etc. oxide or nitride, or It may be a fired body such as a mixture thereof. When the film is formed by the reactive thin film forming method, the reactive gas used for forming the film may be any gas containing a predetermined content of nitrogen gas, oxygen gas or nitrogen / oxygen mixed gas. When a mixture containing nitrogen is used as the evaporation source, an inert gas atmosphere of 100% Ar may be used. Above all, sputtering with a mixed gas of Ar and N ₂ is preferable from the viewpoint of safe operation, since there are few abnormal discharges.

On the other hand, the transparent dielectric material forming the second layer of the transparent dielectric material layer of the present invention is not particularly limited as long as it has an oxygen barrier property and does not contain oxygen itself. As such a transparent dielectric, the above-mentioned known Si ₃ N ₄ , AlN, AlSiN, TiN, Ta
In addition to nitrides and sulfides of metals such as N, NbN and ZnS, fluorides and mixtures thereof can be applied as they are. The second layer is formed as a continuous thin film on the first layer by a physical vapor deposition method (PVD) such as a sputtering method or a chemical vapor deposition method (CVD) similar to the formation of the first layer. Form.

Incidentally, the recording layer used in the optical recording medium of the present invention can be applied to, for example, an optical recording medium of various known optical recording systems such as a light reflection recording layer, a phase change optical recording layer, and a magneto-optical recording layer.

However, the rare earth-transition metal amorphous alloy which is easily oxidized is excellent in the characteristics of the above-mentioned two-layer structure transparent dielectric layer of the present invention, particularly in the oxidation resistance for preventing the oxidative deterioration of the recording layer. Can be advantageously applied to a magneto-optical recording medium using
Examples of the magneto-optical recording layer include the following.

That is, the magneto-optical recording layer can be recorded / reproduced by the magneto-optical effect, specifically, has an easy magnetization direction in a direction perpendicular to the film surface, and creates an arbitrary reversed magnetic domain,
Magnetic metal thin film capable of recording / reproducing information based on the magneto-optical effect, for example, the above-mentioned rare earths such as TbFeCo alloy, GdTbFe alloy, NdDyFeCo alloy, NdFe alloy, PrFe alloy, and CeFe alloy-
Besides the transition metal amorphous alloy film, various known materials such as super multi-layer film of Pt / Co, Pd / Co or the like, or garnet film can be applied.

As a material for the transparent substrate, polycarbonate resin, acrylic resin, epoxy resin, 4-methyl-pentene resin, or the like, or plastic such as a copolymer thereof or glass can be used. Above all, a polycarbonate resin is preferably used in terms of mechanical strength, weather resistance, heat resistance, and moisture permeability.

The magneto-optical recording medium described above has a configuration in which a back surface protective layer is provided on the opposite side of the magneto-optical recording layer from the substrate, as is known.
Furthermore, all the configurations such as a double-sided medium in which the mediums having these configurations are laminated can be applied.

As the structure for providing the back surface protective layer, an inorganic protective layer made of a dielectric material, a metal, etc., an organic protective layer made of an organic resin such as a photosensitive resin, a transparent flat plate laminated together, or a combination thereof is used.

As the dielectric used for the back surface protective layer, a substance with few cracks and pinholes is preferable in order to prevent oxygen and H ₂ O from penetrating from the film surface to the magneto-optical recording layer, like the above-mentioned second layer. _{, Si 3 N 4, AlSiN,} TiN, TaN, NbN, nitrides such as ZnS, can be applied, such as sulfides, or mixtures thereof.

As the metal film of the back surface protective layer, Al, Au, Ag, Cu, Si, Ti, T
A metal film made of a, Cr, Re, Zr or an alloy thereof can be applied. The above inorganic protective layer can be produced by a known vacuum deposition method, sputtering method, or the like.

Further, as the organic resin for the back surface protective layer, a hot melt resin or the like is applied in addition to the above-mentioned photosensitive resin. The organic protective layer is preferably used in combination with the above-mentioned inorganic protective layer, and in this case, the inorganic protective layer is preferably arranged and used so as to be in contact with the recording layer. The back surface protective layer is preferably provided so as to cover at least the side surface of the recording layer.

It is apparent from the characteristics and the like that the various protective layers described above can be applied to, for example, a phase change type optical recording medium other than the magneto-optical recording medium.

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

In a magneto-optical recording medium in which a transparent dielectric film is provided as an optical interference layer between the substrate and the magneto-optical recording layer using a transparent plastic substrate, as described above, a typical conventional AlN, Si ₃ N ₄ , AlSiN, TiN, TaN, NbN, ZnS, etc.When a disk is composed of nitride, sulfide, etc., when these media are subjected to a durability test under high temperature and high humidity, the disk cracks. However, it was observed that the magneto-optical characteristics deteriorated rapidly. This is mainly due to peeling of the dielectric film at the plastic substrate interface.

On the other hand, with the above-mentioned structure, the transparent dielectric layer is made into two layers,
The first layer on the substrate side is the above-mentioned specific nitride oxide or oxide film, and the second layer on the recording layer side is AlN, Si ₃ N ₄ , AlSiN, TiN,
TaN, NbN, ZnS and other nitrides, sulfides and other oxygen-free transparent dielectric film of the magneto-optical disk of the present invention, the peeling and cracking due to deterioration at the interface with the plastic substrate does not occur, recording The layers are also stable over the long term. This is because the nitride oxide and oxide film of the first layer has a high affinity with a plastic substrate such as a polycarbonate substrate, and the enzyme of the first layer and its interface is blocked from the recording layer by the second layer. It seems that it is due to being done. This effect is particularly effective for long-term stability under normal environment, heat cycle, and heat shock.

It is apparent that the above-described effects of the present invention are not limited to the magneto-optical recording medium, and can be similarly exerted in a known magneto-optical medium such as a phase change type and a reflection type. Is widely applicable to optical recording media. As described above, the present invention makes a great contribution to the improvement of the characteristics including the durability of the magneto-optical recording medium among the optical recording media.

Examples of the magneto-optical recording medium of the present invention will be described below.

Example 1 A magneto-optical recording medium having a laminated structure shown in FIG. 1 was prepared and evaluated as follows. In the figure, 1 is a substrate, and 2a, 2
Reference numeral b is the first and second layers of the transparent dielectric layer 2 on the front surface, 3 is a recording layer, 4 is a transparent dielectric layer on the back surface, 5 is a metal reflective layer, and 6 is an organic protective layer.

A substrate 1 made of a polycarbonate resin (PC) disk having a diameter of 130 mm and a thickness of 1.2 mm and having a group of 1.6 μm pitch, and a vacuum of a high-frequency magnetron sputtering device with three targets (Model SPF-430H manufactured by Anerva Corp.). It was fixed in the tank and evacuated to 4 × 10 ⁻⁷ Torr. In addition,
The substrate 1 was rotated at 15 rpm in the film formation.

Then, first, the transparent dielectric layer 2 on the front surface is formed as follows.
The first layer 2a of was formed. Ar / N ₂ mixed gas (N ₂ : 30vol
%) Is introduced into the vacuum chamber, and Ar / is adjusted so that the pressure becomes 10 mTorr.
The N ₂ gas flow rate was adjusted. The target is 100m in diameter
m, 5 mm thick disk with composition In _x Sn _y Bi _z O _{100- (x + y + z)} (x,
y, z is atomic%), the composition ratio (x, y, z) is (40,0,
0), (36,4,0), (20,20,0), (0,40,0), (36,0,
4), (20,0,20), and (20,10,10) were used. High-frequency sputtering is performed at a discharge power of 100 W and a discharge frequency of 13.56 MHz, and the first layer
2a has a film composition of In ₄₀ O ₅₀ N ₁₀ , In ₃₆ Sn ₄ O ₅₀ N ₁₀ , In ₂₀ Sn ₂₀ O
₅₀ N ₁₀ , Sn ₄₀ O ₅₀ N ₁₀ , In ₃₆ Bi ₄ O ₅₀ N ₁₀ , In ₂₀ Bi ₂₀ O ₅₀ N ₁₀ , In ₂₀
Sn ₁₀ Bi ₁₀ O ₅₀ N ₁₀ composite oxynitride film of each composition {(In, Sn, B
i) ON film} was deposited about 200Å.

Next, the target was changed to a disk of a sintered body of Al ₅₀ Si ₅₀ (subscripts indicate composition (atomic%)), and the second layer 2b was composed of Al ₂₅ Si ₂₅ No _{50 under} the same discharge conditions as above. About 1000Å of transparent dielectric film was deposited. Then, the target was Tb ₂₃ Fe ₆₉
Change to a disk of Co ₀₈ (subscript indicates composition (atomic%)),
TbFe was used as the magneto-optical recording layer 3 under the same discharge conditions as above except that the sputtering gas was pure Ar (5N) rather than Ar / N _2.
About 250Å of Co alloy film was deposited.

The target was returned to the AlSi sintered body target again, and the sputtering gas was changed from pure Ar to Ar / N ₂ mixed gas again, and the transparent dielectric film made of Al ₂₅ Si ₂₅ No ₅₀ was used as the rear surface dielectric layer 4 to about 200 Å. Deposited.

Furthermore, the target was changed to a disk of a sintered body of Al ₉₁ Au ₆ Ti ₃ (subscripts indicate composition (atomic%)), and the sputtering gas was changed from Ar / N ₂ to pure Ar (5N) to the metal reflection layer 5. A
About 500Å of lAuTi alloy film was deposited.

Finally, this deposited layer was taken out from the sputtering device and attached to a spin coater. An ultraviolet curable phenol novolac epoxy acrylate resin was applied while rotating the disk, and then passed through an ultraviolet irradiation device to cure the resin to provide an organic protective layer 6 of about 50 μm.

In the above order, PC / (In, Sn, B shown in Fig. 1
i) A magneto-optical disk with a laminated structure of ON / AlSiN / TbFeCo / AlSiN / AlAuTi / organic protective layer was obtained.

Next, the CNR of this disc was measured. Wavelength 830 for measurement
Using a magneto-optical recording / reproducing device (manufactured by Seiko Epson, product name "Venus") that uses a semiconductor laser of nm
It was rotated at 1800 rpm, and recording / reproducing / erasing was performed at a position with a radius of 30 mm.

The signal was reproduced with a reproduction power of 1.2 mW. The optimum laser power at the time of recording was determined to be a value that maximizes the difference between the first harmonic and the second harmonic at the time of signal reproduction. The frequency of the signal is
At 3.7MHz, the duty was 33%. The optimum recording power of each medium was 5.0 mW, the maximum CNR value was 49.0 dB, and the noise level was -51.0 dBm. The noise level is shown in the unit of dBm, which indicates the absolute level based on 1 mW.

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

Next, these disks were left in a high temperature and high humidity atmosphere of 80 ° C. and 85% RH for 200 hours. Optimum laser power after that,
When the CNR noise level was measured, no change was observed compared with the measurement result before standing. When these disk surfaces were observed, no defects such as pinholes, peeling and cracks were observed.

Example 2 A magneto-optical recording medium having the structure shown in FIG. 1 was prepared and evaluated as follows. In the figure, 1 is a substrate, 2a and 2b are the first and second layers of the transparent dielectric layer 2 on the front surface, 3 is a recording layer,
Reference numeral 4 is a transparent dielectric layer on the back surface, 5 is a metal reflection layer, and 6 is an organic protective layer.

A substrate 1 made of a polycarbonate resin (PC) disk having a diameter of 130 mm and a thickness of 1.2 mm and having a group of 1.6 μm pitch, and a vacuum of a high-frequency magnetron sputtering device with three targets (Model SPF-430H manufactured by Anerva Corp.). It was fixed in the tank and evacuated to 4 × 10 ⁻⁷ Torr. In addition,
The substrate 1 was rotated at 15 rpm in the film formation.

Then, first, the transparent dielectric layer 2 on the front surface is formed as follows.
The first layer 2a of was formed. Ar / O ₂ mixed gas (O ₂ : 1vol
%) Is introduced into the vacuum chamber, and Ar / is adjusted so that the pressure becomes 10 mTorr.
The O ₂ gas flow rate was adjusted. The target is 100m in diameter
m, 5 mm thick disk with composition In _x Sn _y Bi _z O _{100- (x + y + z)} (x,
y, z is atomic%), the composition ratio (x, y, z) is (36,0,
4), (20,0,20), (0,36,4), (0,20,20), (20,1)
0, 10), and 5 types of oxide sintered bodies of each composition were appropriately used. High frequency sputtering was performed at a discharge power of 100 W and a discharge frequency of 13.56 MHz, and the film composition of the first layer 2a was In ₃₆ Bi.
₄ O ₆₀ , In ₂₀ Bi ₂₀ O ₆₀ , Sn ₃₆ Bi ₄ O ₆₀ , Sn ₂₀ Bi ₂₀ O ₆₀ , In ₂₀ Sn ₁₀ Bi
About 200Å of oxide film (In, Si) BiO film of each composition of ₁₀ O ₆₀ was deposited.

Next, the target was changed to a disk of a sintered body of Al ₅₀ Si ₅₀ (subscripts indicate composition (atomic%)), and the second layer 2b was composed of Al ₂₅ Si ₂₅ No _{50 under} the same discharge conditions as above. About 1000Å of transparent dielectric film was deposited. Then, the target was Tb ₂₃ Fe ₆₉
Magneto-optical recording layer 3 under the same discharge conditions as described above except that the disk was changed to a Co ₈ alloy (subscript indicates composition (atomic%)) disk and the sputtering gas was pure Ar (5N) rather than Ar / N _2. As
About 250Å of TbFeCo alloy film was deposited.

The target was returned to the AlSi sintered body target again, and the sputtering gas was changed from pure Ar to Ar / N ₂ mixed gas again, and the transparent dielectric film made of Al ₂₅ Si ₂₅ No ₅₀ was used as the rear surface dielectric layer 4 to about 200 Å. Deposited.

Furthermore, the target was changed to a disk of a sintered body of Al ₉₁ Au ₆ Ti ₃ (subscripts indicate composition (atomic%)), and the sputtering gas was changed from Ar / N ₂ to pure Ar (5N) to the metal reflection layer 5. A
About 500Å of lAuTi alloy film was deposited.

Finally, this deposited layer was taken out from the sputtering device and attached to a spin coater. An ultraviolet curable phenol novolac epoxy acrylate resin was applied while rotating the disk, and then passed through an ultraviolet irradiation device to cure the resin to provide an organic protective layer 6 of about 50 μm.

In the above order, PC / (In, Sn) Bi as shown in Fig. 1
A magneto-optical disk with a laminated structure of O / AlSiN / TbFeCo / AlSiN / AlAuTi / organic protective layer was obtained.

Next, the CNR of this disc was measured. Measurement is in Example 1
And exactly the same.

The measurement result shows that the optimum recording power for all media is 5.0 m.
The maximum value of W and CNR was 49.0 dB, and the noise level was -51.0 dBm.

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

Next, these disks were left in a high temperature and high humidity atmosphere of 80 ° C. and 85% RH for 200 hours. Optimum laser power after that,
When the CNR noise level was measured, no change was observed compared with the measurement result before standing. When these disk surfaces were observed, no defects such as pinholes, peeling and cracks were observed.

Comparative Example As described below, except for the single-layer transparent dielectric layer 2 in which the two-layer structure of the first and second layers 2a and 2b of the transparent dielectric layer 2 of Example 1 described above is a conventional single layer, A magneto-optical disk having the same configuration as in Example 1 was created and evaluated.

A disk substrate 1 of a polycarbonate resin (PC) having a disk of 130 mm in diameter and 1.2 mm in thickness and having a group of 1.6 μm pitch was fixed in the same sputtering apparatus as that used in the Examples under the same conditions.

As the transparent dielectric layer 2 on the front surface, Al ₅₀ Si _{50 is used} as a target.
(Supplemental figures indicate composition (atomic%)) and In ₃₆ Sn
Al ₂₅ Si ₂₅ No ₅₀ and In ₃₆ Sn ₄ O _{50 under} the same discharge conditions as in the example using a sintered body of ₄ O ₆₀ and Ar / N ₂ mixed gas (N ₂ : 30 vol%) as a sputtering gas. About 1200Å of N ₁₀ transparent dielectric film was deposited.

Thereafter, the sputtering gas is appropriately changed, TbFeCo is about 250 Å as the recording layer 3, AlSiN is about 200 Å as the back surface protective layer 4, and the metal reflective layer 5 is exactly the same as in Example 1.
AlAuTi was laminated in the order of about 500 Å, and finally an ultraviolet curable phenol novolac epoxy acrylate resin was provided as about 50 μm as the organic protective layer 6. That is, the transparent dielectric layer 2
PC / (A with the same configuration as in Example 1 except that the conventional single layer
We obtained a magneto-optical disk with a laminated structure of (lSiN, InSnON) / TbFeCo / AlSiN / AlAuTi / organic protective layer.

Next, when the characteristics of this disk were measured under the same conditions as in Example 1, the optimum laser power was 5.0 mW, the maximum CNR value was 48.0 dB, and the noise level was -52.0 dBm.

Next, these disks were left in a high temperature and high humidity atmosphere of 80 ° C. and 85% RH for 200 hours. PC / AlSiN / TbFeCo / AlSiN / AlAuT
In the medium having the i / organic protective layer, innumerable cracks were generated after standing and peeling was partially generated. The optimum laser power did not change, but the CNR dropped by 2 dB to 46.0 dB,
The noise level increased by 2 dB to -50 dBm. On the other hand, PC
Although the medium with the composition of / InSnON / TbFeCo / AlSiN / AlAuTi / organic protective layer did not show cracks, peeling, etc. after leaving and change of the optimum laser power, CNR decreased by 3 dB.
The noise level was 45.0 dB, and the noise level increased by 2 dB to -50 dBm.

 The significance of the present invention was shown by this example and the comparative example.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a laminated structure of the embodiment. 1: substrate, 2,
4: Transparent dielectric layer, 3: Recording layer, 5: Metal reflective layer, 6: Organic protective layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-63-166046 (JP, A) JP-A-62-192948 (JP, A) JP-A-62-222453 (JP, A) JP-A-2- 152051 (JP, A)

Claims (6)

(57) [Claims] 1. An optical recording medium having a transparent dielectric layer between a substrate and a recording layer, wherein the transparent dielectric layer is laminated on the substrate, and at least one of In and Sn oxynitride oxides, Alternatively, a first layer made of at least one of In and Sn and Bi oxide or oxynitride, and a second layer made of a transparent dielectric material containing no oxygen, which is laminated on the recording layer side of the first layer. An optical recording medium characterized by the following. 2. The optical recording medium according to claim 1, wherein the nitric oxide or the oxide is amorphous. 3. The optical recording medium according to claim 1, wherein the nitrogen content of the oxynitride is 40 at% or less. 4. The optical recording medium according to claim 1, 2 or 3, wherein the transparent dielectric material of the second layer is a metal nitride or sulfide. 5. The optical recording medium according to claim 1, 2, 3, or 4, wherein the recording layer is a magneto-optical recording layer. 6. The first substrate is plastic.
The optical recording medium according to item (2), item (3), item (4), or item (5).