JPS62281141A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To improve recording and reproducing characteristics and to prevent the deterioration of a thin magnetic film layer by incorporating nitrogen into an intermediate layer formed of silicon nitride in such a manner that the nitrogen content on the substrate side is larger than the nitrogen content on the thin magnetic film layer side. CONSTITUTION:The intermediate layer 3 is formed of the silicon nitride and the N/Si atomic ratio in the silicon nitride intermediate layer 3 is 0.8-1.3, more preferably 0.9-1.1 in average over the entire part of the layer. The prescribed nitrogen concn. distribution in which the nitrogen content on the substrate side in the intermediate layer 3 is larger than the nitrogen content on the thin magnetic film layer 4 side exists in the thickness direction of the intermediate layer 3. The recording and reproducing characteristics are thereby improved and the deterioration of the thin magnetic film layer with age is lessened.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Technical Field of the Invention The present invention relates to a magneto-optical recording medium that performs information recording and +IF generation using heat and light such as laser light.

Prior art and its problems Recording media for magneto-optical memory include MnBi, MnAuGe, MnSb, MnCuB1,
GdFe, TbFe, GdCo, PtCo, TbCo, TbFeCo, GdFeCo, TbFe0. , GdIG, GdTbFe
, GdTbFeCoB1, CoFe204, and other materials are known. These thin IIS! is formed as. Common characteristics of these magneto-optical recording media include the fact that the axis of easy magnetization is perpendicular to the film surface, and that the Kerr effect and Faraday effect are large.

What is required of such a medium is that firstly, the Curie point is around 100 to 200°C and the compensation point is around room temperature, and secondly, defects such as grain boundaries that cause noise are relatively free. Thirdly, magnetically and mechanically uniform +i can be obtained over a relatively large surface h1.

In response to such demands, among the above-mentioned materials, amorphous perpendicular magnetic f41E2 of rare earth-transition metals has recently attracted a great deal of attention.

However, in such a magneto-optical recording medium made of an amorphous thin film of a rare earth transition metal, if the magnetic thin film layer is kept in contact with the atmosphere, the rare earth elements will be removed by oxygen and water in the atmosphere. It becomes selectively corroded or oxidized, making it impossible to record or reproduce information.

Therefore, in general, many studies have been conducted on magneto-optical recording media having a structure in which a protective layer is provided on the surface of a 11t thin magnetic recording layer.

Conventionally, as such a moisture-proof protective layer, attempts have been made to provide vacuum-deposited films or resin films of inorganic materials such as silicon oxide, silicon dioxide, aluminum nitride, silicon nitride, and lead sulfide (Japanese Unexamined Patent Application Publication No. 1983-1993). -80142, etc.) are disclosed.

In a magneto-optical recording medium, it is advantageous to perform recording and reproduction from the substrate side, and a transparent substrate is used as the substrate.

As the substrate for optical disks, resin-based substrates are preferable from the viewpoint of ease of manufacture and handling.Among these, acrylic resins, especially acrylic resins, are preferred from the viewpoints of transparency, productivity, economy, etc. Polycarbonate resin etc. are suitable.

Usually, an intermediate layer of an inorganic material is formed on such a resinous substrate, and a magnetic thin film layer is provided through this intermediate layer.

This intermediate layer has a function as an interference layer, improves the C/N ratio, and has corrosion resistance to prevent deterioration of the magnetic thin film layer.
Hit the function.

The material for such an intermediate layer is, for example, 5iO1Si.
Silicon oxide such as n2, AffiN, Si, N4, Zn
S, Si, Ge, etc. have been proposed (Japanese Patent Application Laid-open No. 1983-
No. 80142, etc.).

Among these, silicon nitride is preferable due to its high C/N ratio and durability, but in the conventionally used film structure,
The C/N ratio, corrosion resistance, durability, etc. are poor, and further improvement is required.

■ Purpose of the Invention The purpose of the present invention is to have excellent recording/111 raw characteristics, prevent deterioration of the magnetic thin film layer, and have excellent corrosion resistance and durability.
Furthermore, it is an object of the present invention to provide a magneto-optical recording medium which has excellent stability in 1-method accuracy against warping and the like.

■ Disclosure of the Invention These objectives are achieved by the present invention described below.

That is, the present invention provides a magneto-optical recording medium in which an intermediate layer made of silicon nitride is formed on a resin substrate, and a magnetic thin ++a layer of rare earth-transition metal is provided on the intermediate layer. The magneto-optical recording medium is characterized in that the nitrogen-containing leaflet on the J, ζ plate side is larger than that on the magnetic thin film layer side.

■Specific structure of the invention Hereinafter, a specific configuration of the present invention will be explained in detail.

An embodiment of the magneto-optical recording medium of the present invention is shown in FIG.

In FIG. 1, a magneto-optical recording medium 1 of the present invention includes a substrate 2
It has an intermediate layer 3 on top.

The intermediate layer 3 of the present invention is formed from silicon nitride.

The N/Si atomic ratio in the silicon nitride intermediate layer 3 is 0.8 to 1.3, more preferably 0.9 to 1.3, as an average of the entire layer.
It is 11.

At this time, if the N/Si ratio is less than 0.8, the amount of reflected light decreases, which adversely affects the recording/reproducing characteristics.

On the other hand, if it exceeds 1.3, the apparent Kerr rotation angle decreases, and the recording/reproducing characteristics are similarly adversely affected.

In the thickness direction of the intermediate layer 3, there is a predetermined nitrogen concentration distribution such that the nitrogen content on the substrate side in the intermediate layer 3 is larger than that on the magnetic thin film layer 4 side, which will be described later.

Such a nitrogen concentration distribution in the silicon nitride intermediate P:f13 is, for example, 1/4 from the substrate 2 side of the silicon nitride intermediate layer 3.
At the N/Si field up to the magnetic thin film layer 4
1.4 times or more, especially 1.5 to 2.5 times, more preferably 1.6 to 2.5 times the N/Si atomic ratio at the position up to 1/4 from the side.
l, 9 (j's).

When this value is less than 1.4 times, the C/N ratio, corrosion resistance, and durability deteriorate. On the other hand, when this value 1 falls within the above-mentioned preferred range of 1.6 to 1.9 (j'), the C/N ratio and durability are significantly improved.

By providing the silicon nitride intermediate layer 3 with the above-mentioned nitrogen concentration distribution, the above-mentioned effect is produced.

1- That is, firstly, by appropriately setting the nitrogen concentration on the substrate side of the silicon nitride intermediate layer 3, the relationship between the substrate (refractive index of polycarbonate resin is about 1.57 at 830 nm) and the silicon nitride intermediate layer 3 is reduced. By effectively preventing reflection at the interface, good recording and +Ij raw characteristics can be obtained.

Second, by keeping the nitrogen concentration in the silicon nitride intermediate layer 3 on the side of the magnetic thin layer 11!2 layer 4 low, Fe
Deterioration of the magnetic thin film layer 4 containing Co and Co as essential components can be effectively prevented.

Note that the nitrogen concentration portion 1fi may be continuous or discontinuous.

The original r ratio distribution of N/Si existing in the x direction of the silicon nitride intermediate layer 3 is determined, for example, by the method described below.

That is, first, the silicon nitride intermediate layer 3 is etched from the conductive thin film layer 4 by ion etching at a constant etching rate, and is etched by SIMS (secondary ion quality Hi analysis), AES (Auger spectroscopy), ESCA, etc. Perform elemental analysis. Then, the time required for carbon C to reach the substrate 2 made of polycarbonate resin or the like is measured.

The time from the beginning to 1/4 and 3/
4 to 7. The N/Si average thickness r-ratio at a predetermined location in the layer is calculated from the elemental analysis results in the layer during the time it takes to reach the H plate.

It goes without saying that the average N/Si original r-ratio of the entire layer can also be calculated.

In order to form the silicon nitride intermediate layer 3 in which the nitrogen concentration distribution exists in the film thickness direction, Si3N and Si are used as targets, and the sputtering rate of both is controlled and the film is formed while changing this. A binary sputtering method is used, or a reactive sputtering method is used, which uses Si as a target in an atmosphere containing nitrogen and forms a film by controlling the nitrogen concentration and changing it.

These sputtering conditions may be normal conditions.

Further, in accordance with this, other vapor phase film forming methods, such as vapor deposition, etc. can also be used as appropriate.

The thickness of the silicon nitride intermediate layer 3 formed in this way is 3.
00 to 1500 people, more preferably 600 to 900 people.

Note that the silicon nitride intermediate layer is usually in an amorphous TT state.

Furthermore, Ar or the like present in the desert atmosphere may also be included.

In addition, in some cases, small 111 A1, Zn, C",
Elements such as Ba may be added.

The substrate 2 on which the silicon nitride intermediate layer 3 described above is formed is formed of resin.

Preferred resins include acrylic resin, polycarbonate resin, epoxy resin, and polymethylpentene resin.

Among these resins, polycarbonate resins are preferred in terms of durability, particularly resistance to warping and the like.

The polycarbonate resin in this case may be any of aliphatic polycarbonate, aromatic-aliphatic polycarbonate, and aromatic polycarbonate, and is particularly preferably aromatic polycarbonate + 51 fat.

Among these, polycarbonate resins made from bisphenol are preferred in terms of melting point, crystallinity, handling, etc.

Among them, bisphenol A type polycarbonate resin is most preferably used.

In addition, the number of polycarbonate resins/Y uniform molecular weight 1j (is,
It is preferable that it is about 000 to 15,000.

The refractive index of such a substrate 2 at 830 nm is usually 1.5.
It is about 5 to 1,59.

Note that since recording is performed through the substrate 2, the transmittance for writing light or reading light is set to be 86% or more.

Further, the substrate 2 is usually disk-shaped, and has a diameter of 1.2 to 1.5
The thickness should be about mm.

Tracking grooves may be formed on the magnetic thin film layer forming surface of such a disk-shaped substrate.

The depth of the groove is about λ/8n, especially λ/6n~λ
/ L 2 n (where n is the refractive index of the substrate)
It is said that Further, the groove 111 is approximately the same as the track 111.

In general, it is preferable to use the magnetic thin film layer located at the four parts of the groove as a recording track part, and to irradiate the writing light and the reading light from the back side of the substrate.

With this configuration, the 117 writing sensitivity and the readout C/N ratio are improved, and the tracking; C/N ratio is improved.
(+The Word of God will become louder.

In addition, other shapes of the substrate may be used, such as a tape or a drum.

F of the silicon nitride intermediate layer 3 mentioned above has a magnetic thin film 11!2.
Layer 4 is installed.

In the magnetic thin film layer 4 of the present invention, +11i information is magnetically recorded by a modulated heat beam or a modulated electric field, and the recorded information is reproduced by magneto-optical conversion. It is.

The material for the magnetic thin film layer 4 is an amorphous film made of an alloy of rare metals such as Gd and Tb and transition metals such as Fe and Co by sputtering, vapor deposition, etc. Moreover, Fe and Co must be combined components.

In this case, the total amount of Fe and CO is 65 to 85a
It is preferable that it is j%.

The remainder is substantially rare earth metals, especially Gd and/or
Or Tb.

Suitable examples include TbFeCo, GdFe
Co, GdTbFeCo, etc.

In addition, these magnetic thin film layers contain C', Afl, Ti, Pt, Si, Mo, Mn, V, N in a range of 10aL% or more.
i, Cu, Zn, Ge, Au, etc. may be contained.

In addition, as a rare earth element, Sc in a range of 10aL% or more F,
Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Dy
, Ho, Er, Tm, Yb, Lu, etc.

The thickness of such a magnetic thin film layer is preferably 0.01 to 1 μm.

In general, it is preferable to provide one or more various protective layers on the opposite side of the magnetic thin layer 11 (layer 4) from the c-plate 2.

In FIG. 1, a protective layer 5 and a protective film 6 are provided.

In this case, the material of the protective layer 5 is not particularly limited as long as it has a function as a protective layer, but preferably a thin film of oxide or nitride.

Examples of oxides include silicon oxide, carbon oxide such as silicon oxide, aluminum oxide, titanium oxide, and silicon oxide.
Rejected lead etc. are suitable.

Further, as the nitride, silicon nitride, aluminum nitride, titanium nitride, boron nitride, etc. are suitable.

Among these, silicon nitride is particularly preferred.

The thickness of such a thin film is approximately 0.1 to 10 μm.

Note that the protective layer 5 may be formed by vacuum deposition, sputtering, or the like.

On the other hand, as the material for protection 1 and 6, various known organic substances may be used.

More preferably, a radiation-curable compound cured with radiation such as an electron beam or ultraviolet rays is used.

The radiation-curable compounds to be used include acrylic acid, methacrylic acid, or acrylic double bonds such as ester compounds thereof, diallyl phthalate, which are sensitive to ionization energy and erase unsaturated double bonds that exhibit radical polymerizability. Polymers, oligomers, polymers, etc. that contain or introduce into their molecules groups that can be crosslinked or polymerized and dried by radiation irradiation, such as allylic double bonds, maleic acid, unsaturated double bonds such as maleic acid derivatives, etc. can be mentioned.

As a radiation-curable monomer, a compound with a molecular size of less than 2000 is used, and as an oligomer, a compound with a molecular size of less than 2000
~10,000 are used.

These include styrene, ethyl acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol methacrylate, 1,6-hexane glycol diacrylate, 1,6-hexane glycol diacrylate, etc., but particularly preferred ones are Examples include pentaerythritol tetraacrylate (methacrylate), pentaerythritol acrylate (methacrylate), trimethylolpropane triacrylate (methacrylate), trimethylolpropane diacrylate (methacrylate), polyfunctional oligoester acrylate (Aronix M-7100, M-5400) , M-5500, M-5700
, M-6250, M-6500, M-8030, M-8
060, M-8100, etc. (Toagosei), urethane elastomers with acrylic modified products of Tuborane 4040), or those into which '1'5' functional groups such as C0OH have been introduced, acrylates of phenol ethylene oxide adducts ( methacrylate), an acrylic group (methacrylic group) on the pentaerythritol condensed ring represented by the general formula below.
or ε-caprolactone-7 ll ll no 1
1', Hatsu 18t-iIr /'-6+1) (C
H2=CHCOOCH2)3-CCH20H (special acrylate A) 2) (CH2=CHCOOCH2)3-CCH2
CH3 (special acrylate B) 3) (CH2=CHC0(OC3H6)n -0
CH2)3-CC82CH3 (Special acrylate C) (Special acrylate D) (Special acrylate E) CH2CH2C00cH=CH2 (Special acrylate F) Compound where m=1, a=2, b=4 (hereinafter referred to as special pentaerythritol) A compound with m=1, a=3, b=3 (hereinafter referred to as a special pentaerythritol condensate B), a compound with m=1, a=6, b20, a special pentaerythritol Condensate C
), m=2, a=6, b=o compounds (hereinafter referred to as special pentaerythritol condensates), and special acrylates represented by the general formula below.

CH2C00CH=CH2 (n 16) (special acrylate G) 8
) CH2=CHCOO-(CH2CH20)4-C
OCH=CH2 (special acrylate H) CH2CH2C00CH=CH2 (special acrylate ■) CH3CH20-CO-(CH2)5-0COCH=C
H2 (special acrylate J) A-(X-Y+-X-A A Niacrylic acid, X:'M+E Alcohol Y:
Polybasic acid (special acrylate K) 12)
A(-M-N+-M-A A Niacrylic acid, M: Dihydric alcohol N: Disalt μ
Acid (Special acrylate) In addition, radiation-curable oligomers include polyfunctional oligoester acrylates represented by the general formula below, acrylic modified products of urethane elastomers, or those into which functional groups such as C0OH are introduced. can be mentioned.

(In the formula, R,, R2: alkyl, n: integer) Also, heat radiation °
A radiation-modified compound obtained by radiation-sensitizing modification of a thermoplastic resin may also be used.

Specific examples of such radiation-curable resins include acrylic acid, methacrylic acid, and ester compounds thereof, which exhibit an unsaturated knee double bond that exhibits radical polymerizability. Cross-linking by radiation irradiation or (
[Contains a group to be combined in the molecule of the heat-il Q4 resin 1,
Or the introduced resin.

Examples of thermoplastic resins that can be modified into radiation-curable resins include vinyl chloride copolymers, saturated polyvinyl sulfate resins,
Examples include polyvinyl alcohol resin, epoxy resin, phenoxy, f-resin, and cellulose derivatives.

Other resins that can be used for radiation sensitivity modification include polyfunctional polyester resins, polyether ester resins, polyvinylpyrrolidone resins, and derivatives (pvp
F-resins, etc. are also active.

The thickness of the protective film 6 made of such a radiation-curable compound is 0.
It is 1-30 micrometers, more preferably 1-10 micrometers.

If the film thickness is less than 0.1 μm, it will not be possible to form a uniform film, and the moisture-proofing effect in a humid atmosphere will not last for one minute.
The durability of the magnetic thin film layer 4 is not improved. Also, 30 μm
If it exceeds this value, the recording medium will warp and the protective film will crack due to shrinkage during curing of the resin film, making it impractical for practical use.

Such a coating may usually be formed by combining various known methods such as spinner coating, gravure coating, spray coating, and dipping. The conditions for coating the coating film at this time are the viscosity of the mixture of coating film composition, the purpose, and 11-
[Appropriate] 1: It can be determined by considering the coating film thickness, etc.

In order to cure such a coating film to form a protective layer, the coating film may be irradiated with radiation such as electric r-rays or ultraviolet rays.

'I'u, - (When using the - line, the radiation characteristics include an accelerating voltage of 100 to 750 KV, preferably 150 to 3
Using a 00KV radiation accelerator, the absorbed dose is 0.5-2.
It is convenient to irradiate to 0 megarats.

On the other hand, when ultraviolet rays are used, some of the radiation-curable compounds mentioned above are usually light-curable.

Gold sensitizer is added.

The photopolymerization sensitizer may be a conventionally known one, such as benzoin methyl ether, benzoin ethyl ether, α-methylbenzoin, α-chlordeoxybenzoin, etc., benzophenone, acetophenone, bisdialkylaminobenzophenone, etc. Ketones.

Examples include quinones such as acedraquinone and phenanthraquinone, and sulfides such as hensyl disulfide and tetramethylthiuram monosulfite.
The photopolymerization sensitizer is 0.1 to 10% by weight based on the resin solid content.
The range p1 is desirable.

In order to cure a coating containing such a photopolymerizable sensitizer and a radiation-curable compound using ultraviolet rays,
Various known methods may be followed.

For example, an ultraviolet light bulb such as a xenon discharge tube or a hydrogen discharge tube may be used.

A protective plate 8 is usually provided on the protective film 6 with an adhesive layer 7 interposed therebetween.

That is, recording and FIT processing are performed only from the back side of the substrate 2 (the side on which the 6fi thin film layer 4 is not provided).
This protection plate 8 is used only in the case of so-called single-sided recording.

Such resin sealing of the protective plate 8 is not particularly required to be transparent, and can be made of various resins such as tyrene, polypropylene, polyvinyl alcohol, methacrylic resin, polyamide, polyvinylidene chloride, polycarbonate, polyacetal, and fluorine. Various thermoplastic resins such as resins, phenolic resins, urea resins, unsaturated polyester resins, polyurethane, alkyd resins, melamine resins, epoxy resins,
Various types of heat radiation such as silicone resin! Polymer resins and the like can be used.

In addition, various inorganic materials such as glass and ceramics can be used as a protective plate 8.
It may also be used as

The shape, ζJ゛ method, etc. of this material are almost the same as those of the substrate 2 described in F.

Such a protection plate 8 is bonded via the adhesive layer 7 as described above. The adhesive layer is usually made of an adhesive such as hot melt resin, and the film thickness is 1 to 1100.
It is said to be about Ii.

Other JJ-1 Instead of using the above protective plate 8, [2 magnetic thin ++q layer 4, protective layer 5. Using one more set of substrates on which the protective film 6 etc. are applied, the image-specific thin film layer 1kll111 is formed.
1.7' l, de) J I+l ya J-) phia
Rokugll LZ 7? -II+ +, A, bond them together from the back side of both boards;! It may also be a so-called double-sided recording type that performs seven recordings.

Furthermore, it is preferable to provide a hard coat layer as a various protective film on the back surface (the surface on which the magnetic thin film layer 4 is not provided) of the substrate 2 and the protective plate 8.

As the material of the hard coat layer, +if mentioned protective film 6 is used.
The material may be similar to that of .

(2) Effects of the Invention The magneto-optical recording medium of the present invention has a silicon nitride intermediate layer having a predetermined nitrogen concentration IHi between the resinous substrate and the magnetic thin film layer. Therefore, it has excellent records and 11th grade characteristics,
Furthermore, there is little deterioration of the magnetic thin film layer over time.

Especially when the substrate is made of polycarbonate resin,
Deterioration of the magnetic thin film layer over time is further reduced. Furthermore, resistance against warping and the like is further improved.

(JL-specific Examples of the Invention) The present invention will now be described in detail by giving examples of the invention.

"Example 1" A silicon nitride intermediate layer was deposited to a thickness of 700 mm on a substrate made of bisphenol A polycarbonate resin (molecular weight 15,000) with a diameter of 13 cm and a thickness of 1.2 mm by reactive sputtering.

Note that during sputtering, in order to provide a predetermined nitrogen concentration bone 47 in the silicon nitride intermediate layer, nitrogen-containing Ar
':f In an ambient atmosphere, Si was used as a target at an operating pressure of IPa, and the nitrogen concentration was temporally controlled.

After layer formation, elemental analysis in the film was performed using Auger spectroscopy without ion etching, and it was found that II! 2
N/Si original fat (X
+) was 1.3'), and the N/Si original r' ratio (x4) from the 1/4th position from the iii-type thin film layer side was 0.7.

In addition, the average N/Si original r-ratio (X) of the entire j model is 1
, O.

On top of this silicon nitride intermediate layer, 21 aL%Tb,
68% Fe, 7cm% Co, 4
cm% Cr alloy thin ++q by sputtering,
A layer with a thickness of 800 mm was formed to form a magnetic thin film layer.

In addition, the target is Fe target with Tb, Co, and C.
The one with the r chip on it was used.

A protective layer of Si3N4 is placed on this magnetic thin film layer to a thickness of 1000 mm.
A layer is applied by sputtering on the person, and on top of this protective layer -F
A coating composition containing the radiation-curable compound described below is used! L
A film was formed using a spinner coat.

(Coating composition) After applying such a coating composition containing 100 parts by weight of polyfunctional oligomer acrylate and 5 parts by weight of photosensitizer, ultraviolet rays were applied to IF (Ac[I?
If) Go to the top 11.

The film thickness at this time was 5 μm.

Incidentally, the same treatment was also performed on the back surface of the substrate shown in -1-. Furthermore, a polycarbonate resin protection plate having a diameter of 13 cm was adhered to the protection +121 using an adhesive to prepare a sample of the present invention (sample No. 1). According to this, sample N (1,1 silicon nitride intermediate layer was prepared in Table 1 above)
Extrapolation samples were prepared in the same manner as in cases No. and 1, except that a silicon nitride intermediate layer having a nitrogen concentration bone 4 as shown in FIG.

The characteristic values shown above were measured for the following samples.

(1) C/N ratio (storage deterioration) C/N ratio of first Jull and 1 at 60℃, 90%R)
Change I11 in C/N ratio after storage for 000 hours was measured under the conditions described in F.

Rotation speed 4 m/sec
Transmission frequency 500Hz resolution
30Hz recording power (830n
m) 3-4mW reproduction power (830nm)
1 mW (2) Pit error rate The pit error rate of EFM (No. 3) was measured at the initial stage and after storage for too long at 60° C. and 90% RH.

The results are shown in Table 1.

Table 1 From the results shown in Table 1, the effects of the present invention are clear.

That is, in the case of the present invention denoted by N(), 1''-No, 3, X+ is larger than x4, and x, /X4
or more than 1.4, especially 1.4 to 2.5, and X is 0.8 to
1.3, all of the C/N ratio, pit error rate, and these values after storage show good results. In particular, NO,1 and N(1,2) show extremely excellent results because the values of X and xl/x4 are within the optimal range.
X is 0.9-1.1, X1/X4 is 16-19
It can be seen that the effect of preventing storage deterioration is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a magneto-optical recording medium showing one example of the present invention. Explanation of symbols 1...Magneto-optical recording medium, 2...J↓ plate 3...Silicon nitride intermediate layer, 4...Magnetic thin film layer, 5...Protective layer, 6...Protective 11 layers , 7... Adhesive layer, 8... Protective plate applicant TDC Co., Ltd.'I

Claims (4)

[Claims] (1) In a magneto-optical recording medium that has an intermediate layer formed of silicon nitride on a resin substrate, and a magnetic thin film layer of a rare class transition metal on the intermediate layer, the substrate side of the intermediate layer A magneto-optical recording medium characterized in that the nitrogen content of the magnetic thin film layer is greater than that of the magnetic thin film layer. (2) The N/Si atomic ratio in the silicon nitride intermediate layer at a position up to 1/4 from the substrate side of the silicon nitride intermediate layer is lower than the N/Si atomic ratio in the silicon nitride intermediate layer at a position up to 1/4 from the magnetic thin film layer side. /S
The magneto-optical recording medium according to claim 1, wherein the i atomic ratio is 1.4 times or more. (3) The magneto-optical recording medium according to claim 1 or 2, wherein the silicon nitride intermediate layer has an average N/Si atomic ratio of 0.8 to 1.3. (4) The magneto-optical recording medium according to any one of claims 1 to 3, wherein the resin substrate is made of polycarbonate resin.