JPS63266651A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To form a magneto-optical recording medium having good durability by forming a transparent dielectric layer of a dielectric transparent oxide layer consisting of the oxide of at least one element selected from a group consisting of In and Sn and having specific electric resistivity or above. CONSTITUTION:The dielectric layer 2 of the magneto-optical recording medium provided with a magneto-optical recording layer 3 via the dielectric layer 2 and further a protective layer 4 at need on a transparent synthetic resin substrate 1 is the dielectric transparent oxide layer consisting of the oxide of at least one element selected from the group consisting of In and Sn and having >=1X10<-1>OMEGA.cm electric resistivity. Such oxide film is, for example, the indium oxide (In2 O3) film and/or tin oxide (SnOx) film which has a sufficiently high oxygen concn. and has a low carrier concn. by defects, etc. The magneto-optical recording medium having extremely high environmental resistance and excellent dynamic characteristics by the improved angle of Kerr rotation is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a magneto-optical recording medium in which information is recorded, reproduced, erased, etc. using light such as a laser. More specifically, a recording layer made of a thin metal film with the direction of easy magnetization perpendicular to the film surface is formed on a transparent synthetic resin substrate, and information is recorded and reproduced using the magneto-optic effect. Concerning magneto-optical recording media with excellent environmental friendliness.

[Prior Art] Various research and developments are being conducted on optical recording media for high-density, large-capacity information recording. In particular, a wide variety of materials and systems have been announced for use in erasable magneto-optical recording media, and their practical application is eagerly awaited.

As the above-mentioned magneto-optical recording material, for example, JP-A-52-
FeTb described in Publication No. 31703, JP-A-56-12
Ferb Gd described in Publication No. 6907, JP-A-58-
Ferb Co, re C described in 73746Q publication
o Dy, re described in JP-A-61-165846
There are already many proposals such as Nd. However, in order to put these information erasable magneto-optical recording media into practical use, it is necessary to further improve the recording and reproducing characteristics, and to protect the majority of the storage materials that make up the recording layer from corrosion such as oxidation. It is said that it is necessary to improve its durability including its oxidation resistance.

On the other hand, for example, Japanese Patent Application Laid-Open No. 59110052 discloses that the recording layer of an optical metering element is sandwiched between two oxygen-free films, at least one of which is a dielectric layer, thereby preventing oxidation of the recording layer. It is proposed to prevent

Furthermore, it is widely known that a dielectric material is provided between such a substrate and a recording layer to improve the Kerr rotation angle. In this case, it is necessary that the dielectric layer does not contain oxygen, and the dielectric layer is made of Ai'N, M[F
2, 7. n3. CcF:+, Affil-+
- It is said that it is preferable to use nitride, fluoride, etc. such as 3NaF and Si3N4.

By the way, among these, AI is said to have excellent environmental resistance! N, S! :+ When we investigated nitride films such as N4, we found that the film formation speed was slow, and the distortion in the film was large, especially when a multilayer film was formed on a plastic substrate. It was found that further improvements were needed, including problems with durability in aspects other than oxidation resistance.

[Object 1 of the Invention] The present invention was made in view of the current situation, and its object is to provide a highly durable magneto-optical recording medium having a recording layer on a transparent synthetic resin substrate via a dielectric M. . In other words,
Specifically, the first objective is to stabilize the environment of the recording medium, and particularly to prevent cracking and peeling due to deterioration of the interface between the substrate and the dielectric layer. A second purpose is to stabilize the interface between the dielectric layer and the magneto-optical alloy layer. A third purpose is to suppress deterioration factors, particularly 112O, which enter the interface of the magneto-optical recording layer through or through the plastic substrate.

[Configuration 2 of the invention] The above objects are achieved by the invention as follows.

That is, the present invention provides a magneto-optical recording medium in which a magneto-optical recording layer and, if necessary, a protective layer are provided on a transparent synthetic resin substrate via a dielectric layer, wherein the dielectric layer is made of a group consisting of In and Sn. This is a magneto-optical recording medium characterized by a dielectric transparent oxide layer comprising an oxide of at least one element selected from the following, and having an electrical resistivity of 1×10' Q·cm or more. Hereinafter, the magneto-optical recording medium of the present invention will be referred to as the present invention medium, and the transparent oxide layer will be referred to as an In and/or Sn oxide layer.

In the inventive medium, the dielectric layer consisting of In and/or sn transparent oxide is formed by physical deposition (physrca+V
apor Deposition: PVD)
Formed by law.

Further, in the medium of the present invention, it is preferable to provide a protective layer made of a metallic titanium film between the oxide film and the magneto-optical film in terms of improving oxidation resistance and moisture permeation resistance. The thickness of the metallic titanium film is preferably 50 Å or less, more preferably 20 Å or less from the recording/reproducing surface.

The dielectric layer of the medium of the present invention may be a dielectric oxide layer of In and/or Sn, as long as it functions as a dielectric layer. Well-oxidized oxides with poor electrical conductivity are preferred. Examples of such oxides include indium oxide (In), which has a sufficiently high oxygen moisture content and a low carrier concentration due to defects, etc.
2O. +) film and/or a tin oxide (SnOx) film. Alternatively, In2O3 and/or SnQx oxide may contain Ta, sb, F, etc. as impurities. Among these, an InQ3 film or an oxide film mainly composed of Inz 03 containing tin oxide is preferable from the viewpoint of durability t1 and low reading laser power. Note that the content of tin oxide in this oxide is 30 wt% or less, preferably 7 wt%.
t% or less, more preferably 3wt in terms of refractive index
% or less.

As mentioned above, these In2O3 and/or SnOx layers are made by known PVD methods such as vacuum evaporation and sputtering. It is preferable to manufacture under conditions where the sliding property is large. For this purpose, sputtering is preferred.

Note that In and/or Sn constituting the dielectric layer of the present invention
Dielectric oxide films containing metal include films known as transparent conductive layers, such as indium oxide films, indium oxide films, etc.
It does not include a tin oxide film (ITO) or the like. In other words, the conductive electrical resistivity known as a transparent conductive film is 10-
The oxide film containing In and/or Sn metals with a resistance of 2-10-4Ω·cii has good thermal conductivity, and the heat dissipates from the medium recording area, which becomes hot in a spot shape due to laser light, to the conductive oxide film side. As a result, the required recording laser power increases, and the bit shape becomes disordered, resulting in a decrease in C/N. Furthermore, an electrochemical current flows between the iron-based alloy layer and the conductive oxide layer in a high humidity atmosphere, promoting environmental deterioration of the magneto-optical recording medium. Therefore, it is difficult to apply the In and/or Snn row right conductive oxide layer to magneto-optical recording media. Furthermore, the conductive oxide layer containing In and/or Sn and having an electrical resistivity of 10<-4 >[Omega].cm has a high concentration of x-rea, causing reflection loss to near-infrared laser light due to plasma vibration.

In order to form an oxide film containing In and/or Sn metal as a transparent conductive film on a transparent plastic disk substrate such as polycarbonate or acrylic resin, it is usually necessary to heat the substrate to about 100°C during film formation. Due to various factors, the groups on the surface of the plastic substrate are disordered, making it difficult to realize a good medium. From the above, the above-mentioned transparent conductive film is not applicable to the present invention.

In the medium of the present invention, the transparent oxide layer is made of an oxide of indium or tin, or an oxide containing both of these metals.

In the medium of the present invention, the tin oxide layer may be any tin oxide as long as it has a dielectric property, specifically, an electrical efficiency of lXl0-1 Ω·cm or more. Preferably, recording
1≦ due to low absorption of laser light used for reproduction
It is SnOX with X≦2.

The refractive index of the dielectric layer made of an oxide containing In and/or Sn must be 1.7 or more with respect to the wavelength of the readout laser beam, and in order to increase the Kerr rotation angle appropriately, the refractive index must be 1.7 or more. 9 or more is preferable.

Next, the effect of the oxide layer containing In and/or sn will be explained in comparison with the conventional technology.

In conventional magneto-optical recording media, a transparent plastic substrate is used, and a dielectric film is provided between the substrate and the magneto-optical recording layer in order to greatly increase the Kerr rotation angle due to film surface reflection. Known SiO, zns, MN, Si:
When a disk was constructed using +N4 or the like, it was observed that when a durability test was conducted under high temperature and high humidity conditions and/or heat recycling, cracks appeared in the disk and the opto-magnetic properties rapidly deteriorated.

According to research conducted by the present inventors, this is mainly due to peeling of the dielectric film at the interface of the plastic substrate.

However, in the case of the disk in which a dielectric oxide film of In and/or Sn metal is used as the dielectric layer according to the present invention, surprisingly, peeling does not occur due to deterioration at this interface, and the durability of the disk is significantly improved. I found out that there is. This is thought to be due to the high affinity between the In and/or Sn metal oxide film and the interface between the plastic book and the polycarbonate substrate in particular. These improvements improve long-term stability under normal environments and are particularly effective against heat recycling and heat shock. Further, by providing a Ti thin film between the dielectric layer and the magneto-optical recording layer of the oxide film of the present invention, there is an effect of trapping O2 or H2O adsorbed on the oxide surface, and magneto-optical recording using oxygen is achieved. This prevents layer deterioration and increases durability. [
Since the coefficient of thermal expansion of i is an intermediate value between the coefficients of thermal expansion of the dielectric layer and the iron-based alloy of the recording layer, stress caused by thermal shock at the interface is reduced and the medium is stabilized. Titanium in the protective layer is oxidized, but its refractive index was originally 1.
．． 8 or more, and the change is small. Titanium may be an alloy as long as the dependence of the refractive index on oxidation is within the above-mentioned small range. The titanium protective layer preferably has a thickness of 50 Å or less from the recording/reproducing surface, and in this case, this layer provides light absorption of 20% or less. A titanium protective layer having a thickness of 2 OA or less is more preferable since the light absorption is 5% or less.

Next, the magneto-optical distribution in the medium of the present invention, that is, the one provided with a dielectric layer of In and/or dielectric transparent oxide layer, and the one provided with a titanium protective layer between this dielectric layer and the recording layer. The protective layer of the B layer 2 synthetic resin substrate and magneto-optical recording layer will be explained.

The magneto-optical recording layer of the present invention may be of any type as long as it can be recorded and reproduced by the magneto-optical effect, and the magneto-optical recording layer can be made to have an easy magnetization direction perpendicular to the known film surface and create arbitrary reversal magnetic domains. Magnetic metal thin films capable of recording and reproducing information based on
, re-Nd alloy such as FeCoDyNdTi, F
E-Pr, re-3m, Fe-Ce alloys, etc. can be used.

As the synthetic resin substrate in the present invention, polycarbonate resin, acrylic resin, epoxy resin, 4-medylbentene resin, and copolymers thereof can be used, but polycarbonate is preferable in terms of mechanical strength, weather resistance, heat resistance, and moisture permeability. Resins are preferred.

As the protective film provided on the side opposite to the substrate of the magneto-optical recording layer of the present invention, dielectric material and/or metal is used. In the case of a protective film, unlike an oxide film, adhesion to the plastic substrate is not a particular problem; N,
M(IF2, zns, CeF:+.

Aif: 3” 3NaF, Si3N4, Sin,
5iOz, Ti0z.

Zr2O3. Nitride, fluoride, oxide, etc. such as In2O3 can be applied. Further, the metal is preferably a substance with low thermal conductivity, such as Ti or Zr. These can be manufactured using the well-known vacuum evaporation method or sputtering method.
Giru.

As described above, the present invention provides dielectric In on a plastic substrate.
By providing a Sn:& group oxide film, a magneto-optical medium is realized which has excellent environmental resistance and excellent dynamic characteristics due to an improved Kerr rotation angle.

The present invention will be explained in detail below.

[Example 1] A disc with a diameter of 200 mm and a thickness of 1.2 mm has a thickness of 2.5 μ.
Acrylic resin (PMMA) with m-pitch groups
The disk substrate was fixed in a vacuum chamber of a three-target high-frequency magnetron sputtering device (Model 5PF-430 manufactured by Anelva vIJ), and the vacuum chamber was evacuated to below 4 x 10-71 orr. Note that the substrate 1 was water-cooled and rotated at 15 rpm.

Next, a mixed gas of Oz, Oz (Oz 2OVo 1%) was introduced into the vacuum chamber, the flow rate of the mixed gas was adjusted so that the pressure was 1 X 10-2 Torr, and the diameter was 100 mm.
Targeting an In disk with a thickness of 5 mm, the discharge power was 10 mm.
High-frequency reactive sputtering was performed at a radio frequency of 136HIIz, and In2 was used as the dielectric layer 2.
Approximately 800 people deposited O3 films. Subsequently, as the recording layer 3, a target of Fe6. Argon gas (5N) was introduced into the vacuum chamber instead of the T b23 CO8 alloy (the suffix indicates the composition (atomic %)), and F was heated under the same discharge conditions as above.
e A Tb Co alloy film of about 100 OA was deposited.

In the first table, In2O3 is used as the protective layer 4 in the same way as the dielectric layer 2.
Approximately 800 people deposited films.

In the above order, PMMA/In shown in FIG. 1(a);+
A magneto-optical recording medium consisting of a laminate of Ox/'rbFOco/Inz Owl was obtained. One point A on this medium (Fig. 1 (
The surrounding area of (see b) was observed using an optical microscope, and it was confirmed that there were no defects or peeling.

This laminate was kept at constant temperature and humidity at 60°C and 90% RTL for 90 minutes.
I left it for a while.

After that, the area around one point A on the medium was examined using an optical microscope.
I noticed that it was the same as before it was left and there were no defects or peeling. Further, when an In2O3 single film was prepared under the same conditions and its electrical resistance was measured, it was found to be an insulating film with a surface resistance of 10) 1Ω/sq or more and a corresponding electrical resistivity value of BxioΩ·cm or more.

[Comparative Example 1] 2.5μ in a disc with a diameter of 2O0mm and a thickness of 1.2mm
Acrylic resin (PMMA) with m-pitch groups
The disk substrate was fixed in a vacuum chamber of a three-target high-frequency magnet [one-instrument sputtering device (Model 5PF-430 manufactured by Anelva ■), and the vacuum chamber was evacuated until the pressure became below 4 X 10-7 Torr. Note that the substrate 1 was water-cooled and rotated at 15 rpm.

Next, N2 mixed gas (N250 VOI%) was introduced into the vacuum chamber, and the flow rate of the mixed gas was adjusted so that the pressure was 1X 10-2 Torr.
Targeting a mm Si disk, the discharge power was 1oov.
, high-frequency sputtering was performed at a discharge frequency of 13.56 HtlZ, and a SiN film was deposited as the dielectric [I2] at a density of about 800 HtlZ.
People piled up.

Next, as record 83, Targera 1 ~ Fe6g'l1
)23Co3 alloy (the suffix indicates the composition (atomic %)'1J
-), a Ferb Co alloy film was deposited to a thickness of about 100 mm under the same discharge conditions as described above.

Finally, about 800 SiN films were deposited as the protective layer 4 in the same manner as the dielectric layer 2.

In the above order, the PMMA/SiN/
19 is a rbFecO/S i N stack, that is, a magneto-optical recording medium.

As in Example 1, the area around point A (see FIG. 1(b)) of this medium was observed using an optical microscope to identify any defects.

It was confirmed that there was no peeling.

This VI layer body was placed at constant temperature and humidity at 60°C and 90% RH.
It was left for 0 hours.

After that, when the area around point A of the medium mentioned above was observed using an optical microscope, peeling along the groups was observed! It was noticed. When the peeled portion was subjected to elemental surface analysis using an X-ray microanalyzer (XMA), it was confirmed that peeling occurred from the dielectric layer 2 portion.

Example 1. Comparative Example 1 demonstrated the effectiveness of the present invention.

[Example 2] A disc with a diameter of 200 mm and a thickness of i and z mm is 1.6 μm.
A polycarbonate resin (PC) disk substrate with groups of 110 pitches was sputtered using a 3-target high-frequency magnetron sputtering device (5PF-430 model manufactured by ANELVA@).
The chamber was fixed in a vacuum chamber and evacuated until the pressure became 4 X 10-7 Torr or less. Note that the substrate 1 was water-cooled and heated at 15 p.
Rotated at pm.

Next, Ar and 02 mixed gas (0210 VOI%) is introduced into the vacuum chamber, and the Ar and 02 mixed gas (7) Flow ffi Rami!
Using a disc of In2O3 sintered body with a diameter of 100 mm and a thickness of 5 mm as a target, high-frequency sputtering was performed at a discharge power of 100 W and a discharge frequency of 13.56/2.
About 800 people deposited an In2O3 film as the dielectric layer 2.

Subsequently, as the first protective layer 5, the target was changed to Ti, intoxicant gas (5N) was introduced into the vacuum chamber, and about 10 Ti films were deposited using the same discharge strip 1 as in the first layer.

Further, as the recording layer 3, a target of F'c6. Tb23C
Ar
Gas (5N) was introduced into the vacuum chamber and about 1000 re Ib Co alloy films were deposited under the same discharge conditions as described above.

In addition, the In2O3 film, [1llQ
A mask was installed so that the Co alloy film was deposited on a substrate with a diameter of 200 mm to a radius of 90 mm from the center.

Finally, this mask is removed and a film is deposited on the entire surface of the substrate, and the target is changed to 11 as the second protective layer 6.
Approximately 200 11 films were deposited under the same discharge conditions as in the first two series.

Hereinafter, PC/Inz O was applied to the second protective layer 6 shown in FIG. 2 in the above order, and the sides of all layers including the recording layer 3 were coated:
A magneto-optical recording medium consisting of a laminate of +/Ti/FOrb CO/li was obtained.

C/N of this laminate [Note: C/N=S/N+101
0(J (noise band)/(resolution bandwidth)]. This measurement was carried out using a magneto-optical recording/reproducing device (Nakamichi 0H3-1
000TVpe (III)), 900rp
Rotate the disc with m and t! If a signal of 1.024 HIIZ is recorded with a 5.0-semiconductor laser beam, then 0.8 m-
It was read out using a semiconductor laser beam. Applied magnetic field is 5000e
(Oersted). The results are shown in Example 2 in Table 1.

Next, this laminate was left at constant temperature and humidity at 60° C. and 90% RH for 500 hours. The subsequent C/interval was measured.

The results are shown in Example 2 in Table 1.

In addition, the surface resistance of In2O3PA reduced by 1q is 10t1
It was an insulating film with an electrical resistivity of 8×10 Ω·cm or more at Ω/sq or more.

[Comparative Example 2] 1.6 μm in a disk with a diameter of 200 mm and a thickness of 1.21
Polycarbonate resin (PC) with big groups
) disk substrate with three targets of high frequency magnets 1 to [
The sample was fixed in a vacuum chamber of a 1-inch sputtering device (Model 5PF-430 manufactured by ANELVA@) and evacuated until the pressure became 4 x 10-7 T'Orr or less. Note that the substrate 1 was water-cooled and heated at 15 p.
Rotated at pm.

Next, intoxication gas (5N) is introduced into the vacuum chamber, and the pressure i
10-2 rorr^ Adjust the gas flow rate, target a ZnS disk with a diameter of 100non and a thickness of 5mm, discharge power of 100W, and discharge frequency of 13.
Approximately 800 1-hole S films were deposited as the dielectric layer 2 by high-frequency sputtering using 56HH2.

Next, as the recording layer 3, the target was Fe6gTb23.
CoB alloy (the suffix indicates the composition (atomic %)) was replaced with about 10% of the FeTbC0 alloy film under the same discharge conditions as above.
00 people deposited.

Finally, the protective layer 4 was changed to an lnS target, and about 800 ZnS films were deposited under the same discharge conditions as described above.

PC/Zn is coated with the protective layer 4 up to the side surfaces of all layers including the recording layer 3 in the laminated structure shown in FIG. 1(a) in the above order.
S/Te rb Co/ZnS @peripheral magneto-optical recording medium (q).

The C/distance of this laminate was measured under the same conditions as in Example 2.

The results are shown in Comparative Example 2 in Table 1.

Next, this laminate was left at constant temperature and humidity at 60° C. and 90% RH for 500 hours. The subsequent C/interval was measured.

When the disk was observed, many cracks were observed on the media surface. The results are shown in Comparative Example 2 in Table 1.

As is clear from Table 1, in Example 2, the C/distance and appearance did not change at all, whereas in Comparative Example 2, the C/dimension decreased from 51 dB to 44 dB, and the appearance also appeared to be due to corrosion deterioration. Wrinkles were observed.

As mentioned above, the effectiveness of the present invention was demonstrated.

[Example 3] 1.6 for a disc with a diameter of 200111 m and a thickness of 1.2 mm.
A disk substrate of polycarbonate resin (PC) having groups with a μm pitch was sputtered using a three-target high-frequency magnet sputtering device (5PF-
430 type) in a vacuum chamber of 4 x 10-7 T.
Cover the exhaust until it is below Orr. Note that the substrate 1 was water-cooled and rotated at 15 rpm.

Next, introduce O2 mixed gas (022 OVOI%) into the vacuum chamber, adjust the flow of O2 mixed gas so that the pressure is 2 x 10-2 rorr, and adjust the flow of O2 mixed gas (022 OVOI%) to a diameter of
m, a disk of sn□z sintered body with a thickness of 5 mm was placed in Targetera 1.
~, discharge power 50W, discharge frequency 13.56)I
High frequency sputtering was performed using n2 to deposit a 5nOz film as the dielectric layer 2 in a thickness of approximately 800.

Next, as the first protective layer 5, change the target to [i^
``Gas (5N) was introduced into the vacuum chamber and approximately 10 I films were deposited under the same discharge conditions as above.

Furthermore, as the recording layer 3, the target was changed to an rbFeco composite target, ^r gas (5N) was introduced into the vacuum chamber, and about 1000 FelbCO alloy films were deposited under the same discharge conditions as described above.

Finally, a Ti target was used as the second protective layer 6, and about 200 films were deposited using the same discharge thread 1 as described above.

PC/sn□x/T with the second protective layer 6 shown in FIG. 2 covering the side surfaces of the remaining layers including the recording layer 3 in the above order.
One i/FerbCo/Ti v4Fff body, ie, 1 q of magneto-optical recording medium was prepared.

The C/N of this laminate [C/N=S/N+101
oa (noise band)/(resolution bandwidth)] was measured.

This measurement was carried out using a magneto-optical recording/reproducing device (Shmichi 0H3-10).
00-cho VI) e (I [I ) ),
Rotate the disk at m and convert the signal of 1.024 to 2 to 7.5
After recording with mW semiconductor laser light, reading was performed with 0.8 mW semiconductor laser light. The applied magnetic field is 5000e (Oersted). The results are shown in Example 3 in Table 2.

Next, this laminate was left at constant temperature and humidity of 60° C. and 90% Rt+ for 500 hours. The C/N was then measured.

The results are shown in Example 3 in Table 2. Further, when observed from the disk surface, no wrinkles, stains, etc., which are caused by corrosion deterioration, were observed. Table 2 also includes the results of Comparative Example 2 described above for comparison.

In addition, the surface resistance of the 1q 5nOz film is 108Ω/S.
It was an insulating film with an electrical resistivity of Q or more and an electrical resistivity of 8×100 cm or more. Furthermore, when the refractive index of the film was measured using an ellipsometer (manufactured by Mizojiri Kogaku@), it was found that this 5n02 film had a refractive index of 2.0 at a wavelength of 8300 m.

Table 2 As is clear from Table 2, in Example 3, the C/N and appearance hardly changed, whereas in Comparative Example 2, the C/N decreased from 51 dB to 44 d8, and the appearance also seemed to be due to corrosion deterioration. wrinkles were observed.

The reason why the output power of the semiconductor laser is larger in this example than in Example 2 is that SnOx than ln2Oxt.
This is probably due to the low refractive index of the layer.

[Example 4] The following study was conducted as one of the corrosion resistance evaluations.

1000mm thick dielectric SnO2-containing In2O3
A thin film was formed on a water-cooled glass substrate of 10 x 2 Omm square and 1.2 mm thick by high frequency sputtering in the same manner as in Example 2. The sputtering strip f[ is Ar10z mixed gas (0
2:2 Ovo 1%) and the gas pressure is l x 10-2 To
rr, target is In-8n (Sn: 5wt%
) was an alloy. Formed SnO2-containing 1112O
The three films had an electrical resistivity of 1×10Ω-CIll, a surface resistance of 100)1Ω/SQ or more, and were dielectric.

The magneto-optical film was made of Fe6gC0B Tl) on a 1.2 mm thick polycarbonate substrate with the same dimensions as in Example 2.
It was formed by high frequency magnetron sputtering using a No. 23 alloy target in an Ar gas atmosphere.

Using the two films thus formed as electrodes, a 5em
The electrodes were immersed in a 0.1 mol/1 Naα solution while facing each other at an interval, and the current flowing between the electrodes was measured for 120 minutes.

A slight current flowed and the total amount of H was 1.4×10 −2 coulombs.

[Comparative Example 3] Conductive (SnO2-containing) n2O3 with a film thickness of 1000 people
A thin film was formed on a glass substrate having the same dimensions as in Example 4 by high frequency sputtering using the same apparatus as in Example 2. The target is Inz 03-3nOz (5wt%5nO
z＞Sintered target in Ar atmosphere, ``+ x 1o-
The substrate temperature was 130° C. with a gas pressure of z rorr. The formed In2O3 film containing SnO2 has an electrical resistivity of 5.
It was plated with a transparent conductive film having a surface resistance of 500 Ω/SQ and a width of 10 −3 Ω·cm.

rec formed on the same polycarbonate as in Example 4.
When oTb magneto-optical films were used as opposing electrodes and immersed in a 0.1 mol/1 Naα solution in the same manner as in Example 4, a considerable current flowed between the electrodes. The total charge during 120 minutes was 1.3 coulombs.

From the comparison with the above-mentioned Example 4, it was confirmed that in a high humidity atmosphere, in the magneto-optical film formed on the conductive In2O3 film as in Comparative Example 3, a local battery is formed and causes deterioration. It was confirmed that in the dielectric 1n2O3 film as in Example 4, such deterioration was improved to a large rlJ.

[Example 5] In Example 2, SnO2 was used instead of the In2O3 layer.
A medium was prepared in exactly the same manner as in Example 2, except that an In2O3 layer containing 5002 was formed using a target made of In2O3 containing 7 wt% of . (The q medium is PC/ In2O3 (5nOz > / It/
This happened with the F'eTbCo/Ti configuration.

When the same test as in Example 2 was conducted, the same results as in Example 2 were obtained.

[Example 6] In place of the In+ 03 layer in Example 2, button 02
Except that the In2O3 layer containing SnO2 was formed using a target made of In2O3 containing 30 wt% of
A medium was prepared in exactly the same manner as in Example 2. The obtained medium was PC/Tnz 03 (5no2)/Ti
/ FerbCo/ri. When the same test as in Example 2 was conducted, the same results as in Example 2 were obtained.

[Example 7] 2 discs with a diameter of 200 mm and a thickness of 1.2 III
．． Acrylic resin (P
A disk substrate of MMA) was sputtered using a three-target high-frequency magnetron sputtering device (5PF-430 manufactured by ANELVA (11)).
4 x 10-7'ror
Exhaust until the temperature is below r. Note that the substrate 1 is water-cooled,
It was rotated at 100 rpm.

Next, introduce Ar and 02 mixed gas (022 OVOI%) into the vacuum chamber, adjust the flow rate of the mixed gas so that the pressure is I x 10-2 rorr, and target an In disk with a diameter of iomm and a thickness of 5 mm. and the discharge power is 10
Approximately 800 In2O3 films were deposited as dielectric layer 2 by high frequency reactive sputtering at 0W and discharge frequency 13.56)11Z.

Subsequently, the target was changed to a target for recording layer 3 deposition, that is, N'7.50"17.5[e52.5CO22,5
Argon (Arbon) gas (5N) was introduced into the vacuum chamber instead of the alloy (the suffix indicates the composition (atomic %)), and a NdDVF'eCO alloy film of about 1000% was heated under the same discharge conditions as above.
People piled up.

Finally, about 800 In2O3 films were deposited as the protective layer 4 in the same manner as the dielectric layer 2.

In the above order, tPMMA/In2O3 is shown in FIG. 1(a).
A laminate of /NdDVFeCO/Inz Owl, that is, a magneto-optical recording medium was obtained. One point A on this medium (Fig. 1(b)
)) Observe the surrounding area with an optical microscope to find any defects.

It was confirmed that there was no peeling.

This laminate was heated to 200°C under constant temperature and humidity at 60°C and 90%
I left it for a while.

Thereafter, the area around point A of the above-mentioned medium was observed using an optical microscope, but it was the same as before being left, with no defects or peeling, and no changes compared to before the test.

Furthermore, when a single Inz 03 film was prepared under the same conditions and its electrical resistance was measured, it was found to be an insulating film with a surface resistance of 108 Ω/SQ or more and a corresponding electrical resistivity value of 8×100 cm or more.

[Comparative Example 4] When making an Inz 03 film using the same equipment as in Example 2, the substrate was heated at 100°C and the target was In2Ox (5wt%5
A disk was produced under the same conditions as in Example 2, except that the sputtering gas was covered with pure^r gas (5N).

The obtained friz 03 (5nO2) film was a transparent conductive film with a surface resistance of 500 Ω/sq and an electrical resistivity of 4×10 −3 Ω·cm. This disk was rotated at 90 rpm, and a signal of 1,024)flz was recorded with a 5.04 semiconductor laser beam, and then read out with a 0.8 m semiconductor laser beam, and the C/N was 44 dB. When the laser light power was increased to 8.5mW, it was 49 dB.
The value of was obtained.

From this, conductive Inz 0 used as a transparent electrode
It has been found that a medium using a multilayer film having the same structure as a 3.3 (5 nOz) film has a large energy loss in the writing laser power, which is undesirable.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are a cross-sectional view and a plan view of a laminate in an example. FIG. 2 is a sectional view of Haku's embodiment. 1: Substrate, 2: Dielectric layer, 3: Recording layer. 4.5.6: Protective layer

Claims (1)

[Claims] 1. A magneto-optical recording medium in which a magneto-optical recording layer is provided on a transparent synthetic resin substrate via a transparent dielectric layer, and further a protective layer is provided as necessary, wherein the transparent dielectric layer is made of In and A magneto-optical recording medium characterized by a dielectric transparent oxide layer having an electrical resistivity of 1×10^-^1 Ωcm or more and made of an oxide of at least one element selected from the group consisting of Sn. . 2. The magneto-optical recording medium according to claim 1, wherein the transparent oxide layer is In_2O_3. 3. Claim 1, wherein the transparent oxide layer is a mixed oxide containing indium oxide as a main component and tin oxide.
Magneto-optical recording medium as described in . 4. The magneto-optical recording medium according to claim 3, wherein the indium oxide is In_2O_3 and the tin oxide is SnO_2. 5. The magneto-optical recording medium according to claim 3 or 4, wherein the content of the tin oxide is 30 wt% or less. 6. The magneto-optical recording medium according to claim 5, wherein the content of the tin oxide is 7 wt% or less. 7. The magneto-optical recording medium according to claim 6, wherein the content of the tin oxide is 3 wt% or less. 8. The magneto-optical recording medium according to claim 1, wherein the transparent oxide layer is made of SnO_X with 1≦X≦2. 9. Claim 1, wherein a metallic titanium layer is provided between the transparent dielectric layer and the magneto-optical recording layer as the protective layer.
9. A magneto-optical recording medium according to items 8 to 9. 10. The magneto-optical recording medium according to claim 9, wherein the metal titanium layer has a thickness of 50 Å or less. 11. The magneto-optical recording medium according to any one of claims 1 to 10, further comprising a second protective layer on a side of the magneto-optical recording layer opposite to the transparent synthetic resin substrate. 12. The magneto-optical recording medium according to claim 11, wherein the second protective layer comprises an oxide layer of at least one element selected from the group consisting of In and Sn. 13. The magneto-optical recording medium according to claim 11, wherein the second protective layer is a metallic titanium layer.