JPS63171454A - Magneto-optical medium - Google Patents

Abstract

PURPOSE:To permit formation of a magneto-optical medium which has excellent adhesiveness to a recording layer and has good stability with lapse of time by using a specific compound nitride layer for a protective layer of the magneto- optical medium. CONSTITUTION:The protective layer is formed by using at least one kind of metal selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo or W and the compound nitride consisting of aluminum and nitrogen is formed as the protective layer on a light incident side of a magnetic layer formed on a substrate consisting of a synthetic resin, glass, etc. Said protective layer has affinity to the magnetic layer and substrate and does not peel or crack. Since the protective layer does not allow the permeation of moisture and air, said layer is not deteriorated by the moisture and air. The magneto-optical medium having the excellent stability with lapse of time is thus obtd.

Description

[Detailed description of the invention] (Industrial application field) 1= The present invention relates to a magneto-optical medium suitable for magneto-optical recording and the like.

(Prior technology) Among optical memory devices, ER is capable of additional recording and erasing.
AAABIE is now on the verge of reaching the stage where magneto-optical recording media are closest to being put to practical use. As a magneto-optical recording medium, thin films of rare earth metals and transition metals are the most excellent in terms of overall characteristics, but a fatal flaw is that they lack corrosion resistance.

In other words, many defects are exposed due to corrosion, such as a decrease in coercive force, which is a necessary condition for high-density recording, a decrease in Kerr rotation angle, which is a necessary condition for a high B/M ratio, and an increase in .

Conventionally, two methods have been used to deal with this problem. That is.

(1) Improving corrosion resistance using additives.

(-) Forms a protective film to improve corrosion resistance.

The present invention is the most effective of the above two methods. First, high melting point oxides such as 81 have been proposed as protective films, but these have high reactivity with Tt)%ye, etc., that is, magnetic layer Since the reactivity at the interface with the oxide layer is high, it is preferable to avoid deteriorating the magnetic layer.
Nitride films such as 11M are made of materials that do not contain oxygen, and therefore are less likely to oxidize the magnetic layer, resulting in good retention. ! It has been revealed that it has certain characteristics. However, nitrides generally have poor adhesion to substrates;
Ninth, peeling under high temperature and humidity was a problem.

Furthermore, magneto-optical media have a structure in which a synthetic resin, glass, etc. is used as a substrate and a magnetic layer is provided on this. However, especially when the substrate is made of synthetic resin such as polycarbonate resin or acrylic resin, the magnetic layer and the substrate are Occurrence of cracks and peeling due to poor affinity with the layer f1 Contained in the substrate 9],
Deterioration of the magnetic layer due to small amounts of air or moisture passing through is a problem, so the protective layer has no affinity with the magnetic layer or substrate, does not allow moisture or air to pass through, and is not susceptible to moisture or air. It is required to be hot water that does not deteriorate easily, and in addition, a protective film is placed on the light incident side of the magnetic layer (writing and reading light).
In the K design, transparency is required to allow sufficient incident light to reach the magnetic layer.

Among nitrides, those that are transparent and have sufficient corrosion resistance even when made into a thin film are: 81. Although there are only a limited number of materials such as N, AIM, Orb%ZrM, Tie%libM, and Tag, which have excellent corrosion resistance and thermal properties, they are opaque and cannot be used on the light incident side. It could not be used as a protective film.

The present inventors solved the above-mentioned defects (particularly the adhesion to resin substrates) while maintaining the non-interfacial reactivity of Al1 etc. : For the purpose of improvement, we investigated the V4 film and found that a composite nitride containing MuIN satisfies the above requirements, leading to the present invention.

That is, the gist of the present invention is to provide a magneto-optical medium in which a magneto-optical active layer is provided on a substrate, in which TI, ZrlHf%V,
A magneto-optical medium is provided in which a composite nitride consisting of at least a metal selected from 11b% Ta, Or% Mo or W, aluminum and nitrogen is formed as a protective film.

(Structure of the invention) The present invention will be explained in detail below.

First, as the substrate used in the present invention, 1. Examples include glass, plastics such as acrylic resins and polycarbonate resins, and metals such as aluminum, but the present invention is particularly effective when using synthetic resins such as polycarbinate and acrylic resins as substrates. .

The thickness of the substrate is generally about 1-2 cm.

Examples of the magneto-optical active layer provided on this substrate include amorphous magnetic alloys of rare earths and transition metals such as TbFe%TbFe0o, TI)Oo, and MnB1, Mn0
A polycrystalline perpendicular magnetization film such as uBi is used. It is particularly effective when used for deposition type alloy magnetic voices.

In the present invention, T1, Zr,
A composite nitride consisting of metals such as Hf%V, Nb%Ta, Or, Mo, and W, aluminum, and nitrogen is formed as a protective film.

Composite nitrides include nitrides IM and Ti)f.

ZrN, HtM, VM%ypw, Tan, Orb,
Mob, mixtures of nitrides of WM and solid solutions.

Among these, preferable nitrides are MbM and Tan.

The component ratio of the composite nitride is as follows: As the ratio of M1 atoms to other metal atoms in the composite nitride, A1 is about 'to' or less than X atoms, and metals other than A1 are about /-J-0 atoms x. It's good to be considered that way.

VM, Ml+M, TaM is the content of the metal element l
Atomic power, ~30 atomic % is the preferred composition.

The selection conditions for the above composition are as follows: light transmission of the composite nitride thin film ``JA (light wavelength 100 nm% film pi 1.1000^
(on the glass substrate) is preferably 70X or more, and it is preferable to select it so that the generation of cracks described below is substantially smooth. can.

The composite nitride protective film can be formed by the usual physical vapor deposition (PVD) method as described below, chemical vapor deposition method such as Goods T OV D, or coating using a liquid phase such as alkoxide, such as a spin code.

l) Deposit a protective film on the substrate by electron beam evaporation or sputtering using a nitride sintered target having the composition described above. λ) Co-evaporation of an AIN target and other nitrides, or sputtering using a composite target method in which another nitride is placed on an AIN target, 3) Metal target formation using reactive ion blasting or reactive sputtering. There are several methods that can be used. The thickness of this protective layer is about 10A to JOOO^, preferably j0λ to KoOo.

Selected from grade A.

If the film deposition rate is too fast, the affinity with the substrate will decrease,
If it is too slow, productivity will be affected, so when the magneto-optical body according to the water passing invention is used as a magneto-optical recording medium, the above-mentioned composite nitride protective layer should be placed on the recording and reproducing light incident side, which has excellent transparency. It is desirable to use the In most cases, the recording/reproducing light is incident from the substrate side, so the protective film of the present invention is often deposited on the substrate.

When glass is used as the substrate, moisture and air almost never enter from the substrate side, so the protective layer of the present invention may not be provided between the substrate and the magnetic layer, but may be provided only on the opposite side. .

When the substrate is made of synthetic resin such as polycarbonate,
Since moisture and air may enter from the substrate side, it is necessary to provide the protective layer of the present invention between the substrate and the magnetic layer.

It is also possible to employ the protective layer of the present invention on one side of the magnetic layer and use the other side a as another protective layer, in which case BN, 814N
4. Nitride such as Tie%ZrN%NbN%Tan,
Or carbides such as Tl01It)O, Ta0%B10, TaBL@, Ora1. , oosi,, vs
Quarride such as T1ε1■ and silicon oxide can also be used as the protective layer. Of course, the protective layer of the present invention may be used on the other side.

The protective layer of the present invention can also be interposed between a magnetic layer and a protective layer that has excellent affinity with the magnetic layer.

A magneto-optical medium having such a configuration can be used not only for magneto-optical memory but also for other devices that utilize the magneto-optical effect, such as optical isolators.

Example: On the erosion part of a sintered aluminum target with a diameter of φ inch (at the same radius as the center of the target, on the circular edge of j5+), 0*wPp, thickness l■ 'ra pieces were placed at equal intervals. and the flow rate j0
800M, flow rate/OBQQM, gas pressure 72K torr, input high frequency power (z3.
tAvilgm) 3oow for 10 minutes! A dielectric layer was obtained which appeared from a transparent membrane of new ztooλ which had been subjected to gnetron battering. The light transmitting water of the dielectric thin metal on the glass substrate has a light wavelength t 00 after correcting the light reflection of the glass substrate.
It was 22x in nm, INl, and OOnm.

Using polycarbonate substrate - AITaM layer<toθλ)
-TbFe layer (100k) -AlTali layer (zo
oλ) was fabricated. The sputtering conditions are the same as described above.

A similar fabrication was made in which a TbFe layer was sandwiched between 7'jAIN films, but peeling occurred after fabrication on a polycarbonate substrate, but MuIT! No results were obtained using LM t-.

(Effects of the Invention) According to the present invention, a magneto-optical medium with good stability over time can be obtained without erosion of the adhesion of the recording layer.

Claims (3)

[Claims] (1) In a magneto-optical medium in which a magneto-optical active layer is provided on a substrate, Ti, Zr, Hf, V, Nb, Ta, Cr, M
1. A magneto-optical medium formed by forming a composite nitride of at least one metal selected from o or W, aluminum and nitrogen as a protective film. (2) The magneto-optical medium according to claim 1, wherein the composite nitride comprises at least one metal selected from Nb or Ta, aluminum, and nitrogen. (3) The magneto-optical medium according to claim 1, wherein the protective film is formed in direct contact with the magnetic layer.