JP2707808B2 - Method for manufacturing magneto-optical recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magneto-optical recording medium.

[Conventional technology]

Optical discs are receiving attention as one of large-capacity file memories. Above all, magneto-optical disks have the advantage that recorded information can be rewritten,
A wide range of applications including code data file memories and image file memories are being actively studied in various places.

As the recording medium, a first dielectric layer made of SiN, a recording made of an amorphous magnetic alloy film such as TbFeCo formed by a combination of a rare earth metal and an iron group transition metal on a resin substrate such as polycarbonate. There is known a three-layer configuration in which a layer and a second dielectric layer made of SiN are formed in this order, or a four-layer configuration in which a reflective film such as Al is further formed. Magneto-optical disks using these are already at a practical level, including in the field of code data file memory for personal computers.
The application is expected to expand. With the expansion of applications, high reliability is required to operate stably even in harsh environments.

Initially, the SiN of the first dielectric layer had a weak adhesive force to the polycarbonate substrate, and thus sometimes peeled off in a high-temperature and high-humidity environment. On the other hand, it has been known that, as a result of improving the film stress of SiN and the like, the adhesive force is improved, and a highly reliable disk with no problem can be obtained even in a high-temperature and high-humidity environment.

In recent years, a method of forming an oxide of Ta (TaOx) between SiN and a polycarbonate substrate has been proposed to further improve the adhesive force (Japanese Patent Application Laid-Open No. 64-189049).

The method using a sintered body Ta ₂ O ₅ targets oxides, the Ar gas as the sputtering gas, and forming a TaOx on a resin substrate such as polycarbonate.

[Problems to be solved by the invention]

However, in the above-described conventional magneto-optical recording medium, in forming a film of TaOx, the target is a sintered body, and when a large power is applied to the target, the target may be broken. Film deposition rate is very slow. On the other hand, when reactive sputtering is performed using a Ta target and a mixed gas of Ar and O ₂ as a sputtering gas, a large electric power can be applied to the target. The film deposition rate was increased (100 to 200 A / min), which proved to be suitable for mass production of media. However, using a Ta target, when forming the TaOx by reactive sputtering and the sputtering gas, a mixed gas of Ar and O _2, Improper selection of deposition conditions, resulting transparency is compromised metallic film Or the adhesive strength is reduced.

An object of the present invention is to select a film forming condition of TaOx formed by reactive sputtering using a mixed gas of Ar and O ₂ as a sputtering gas with respect to a Ta target, so that an adhesive force to a resin substrate is reduced. An object of the present invention is to provide a recording medium which forms strong TaOx and has excellent peel resistance.

[Means for solving the problem]

The magneto-optical recording medium of the present invention, at least on the substrate,
A first dielectric layer composed of an oxide of Ta (TaOx), a second dielectric layer composed of SiN, a recording layer composed of an amorphous magnetic alloy formed by a combination of a rare earth metal and an iron group transition metal, In a magneto-optical recording medium formed in the order of a third dielectric layer made of SiN, the first dielectric layer has a partial oxygen pressure of 0.045 to 0.09 Pa relative to a Ta target.
_A film is formed by reactive sputtering using the mixed gas of ₂ as a sputtering gas.

Embodiment Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view showing one embodiment of the present invention.
The magneto-optical recording medium shown in FIG. 1 has a thickness of 1.2 mm, a diameter of 130 m.
a first dielectric layer 2 having a thickness of 300 mm made of a tantalum Ta oxide (TaOx), a second dielectric layer 3 having a thickness of 600 mm made of silicon nitride SiN, and iron-cobalt terbium The recording layer 4 is made of TbFeCo and has a thickness of 700 、, and the third dielectric layer 5 is made of silicon nitride SiN and has a thickness of 800 順 に.

The dielectric layer 2 made of a tantalum Ta oxide (TaOx) and having a thickness of 300 mm was formed using a tantalum Ta target using argon Ar.
It is formed at a power density of 9.6 w / cm ² by reactive sputtering using a mixed gas of oxygen and oxygen O ₂ (30% O ₂ ) as a sputtering gas.

According to the experiment, the TaOx film deposition rate shows a peak near 0.15 Pa with the increase of the sputtering gas pressure and then monotonously decreases as shown by the film deposition rate curve v in FIG. At a sputtering gas pressure of more than 0.15 Pa, TaOx becomes a transparent film having a refractive index of 2.07 to 2.1 as shown as a refractive index curve n in FIG. It becomes a metallic film with impaired properties.

Here, six types of media samples A having transparent TaOx prepared in the range of the sputtering gas pressure greater than 0.15 Pa
To F are shown in Table 1 below.

In these media samples, the second and fourth dielectric layers made of a SiN film and the recording layer made of TbFeCo are:
All had the same configuration as shown below.

That is, the power density of the second and fourth dielectric layers 3 and 5 made of a SiN film is increased by reactive sputtering using a Si target and a mixed gas of Ar and N ₂ (50% N ₂ ) as a sputtering gas. 8w / cm ^2, the sputtering gas pressure 2.5 × 10 ^- is created in Pa.

Further, the recording layer 4 of TbFeCo having a thickness of 700 mm was formed by a binary DC magnetron sputtering method using a Tb target and an FeCo target while rotating the substrate to an Ar gas pressure of 0.08.
Power density of Pa, Tb target and FeCo target,
Each of which is created by the 1.5 w / cm ² and 3.0 w / cm ^2.

After two sheets of each of the above-described six types of media were closely adhered to each other by a hot melt method, an environmental test was performed for 1000 hours under the temperature and humidity conditions of 80 ° C. and 90% RH. An environmental test was also performed on a conventional medium sample in which TaOx was not formed between the substrate and the SiN layer.

As a result, peeling of the film was observed in the media samples E and F and the conventional media sample, but the media samples A to D
Did not endure any abnormalities.

TaOx media samples A~D, to the Ta target, a mixed gas of Ar and _{O 2 (30% O 2)} , those which have been produced by reactive sputtering of a range of sputtering gas pressure 0.15~0.30Pa is there. In this case, the amount of oxygen during sputtering is in the range of approximately 0.045 to 0.09 Pa, as indicated by the oxygen partial pressure range w in FIG. Furthermore, when using a mixed gas of Ar and O _{2 as} a mixed gas of Ar and O ₂ during TaOx film formation, a good film with strong adhesive force can be obtained in almost the same range when expressed in terms of oxygen partial pressure. It was confirmed.

Note that the medium configuration is not limited to the above-described one, and an Al layer is further formed on the third dielectric layer made of SiN.
It is needless to say that the same effect can be obtained for a medium configuration having a reflective film formed thereon.

〔The invention's effect〕

Since the magneto-optical recording medium of the present invention can realize a magneto-optical recording medium having a stronger adhesive force to a resin substrate than ever, a highly reliable magneto-optical recording medium having excellent peel resistance can be provided.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing an embodiment of the present invention, and FIG. 2 is a characteristic diagram of the embodiment shown in FIG. 1 ... substrate, 2, 3, 5 ... dielectric layer, 4 ... recording layer, v ...
... film deposition rate curve, n ... refractive index curve, w ... oxygen partial pressure range.

Claims (1)

(57) [Claims] 1. A first dielectric layer made of at least Ta oxide (TaO _x ) on a substrate, and a second dielectric layer made of SiN formed on the first dielectric layer A recording layer made of an amorphous magnetic alloy film formed by a combination of a rare earth metal and an iron group transition metal formed on the second dielectric layer; and a film formed on the recording layer A third dielectric layer made of SiN, wherein the first dielectric layer has an oxygen partial pressure relative to a Ta target.
It is formed by forming a film by reactive sputtering using a mixed gas of Ar and O _{2 in} a range of 0.045 to 0.09 (Pa) as a sputtering gas, and thereafter, the second dielectric layer, the recording layer, and the third A method of manufacturing a magneto-optical recording medium, wherein the dielectric layers are sequentially formed.