JP2748448B2 - Method of manufacturing magneto-optical disk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A method for manufacturing a magneto-optical disk is disclosed. The purpose of the present invention is to obtain a magneto-optical disk having good read stability and high recording sensitivity. )-In forming a recording film composed of a transition metal (TM) amorphous alloy film, the recording film was formed by sputtering to an oxygen concentration of 8000 to
A film is formed using a target of a 15,000 ppm rare earth-transition metal amorphous alloy.

[Industrial applications]

The present invention relates to a method for manufacturing a magneto-optical disk.

A magneto-optical disk is a large-capacity rewritable recording medium, and is used as an external storage device of a computer or the like.

[Conventional technology]

A magneto-optical disk cannot be overwritten like a magnetic disk, and therefore has a low data transfer speed. At present, as a method of high-speed transfer of a magneto-optical disk, it is considered to rotate the disk at high speed. However, since recording on a magneto-optical disc is thermomagnetic recording, the recording sensitivity must be increased with respect to high-speed rotation of the disc.

In general, to increase the recording sensitivity, there is a method of lowering the Curie temperature of the magnetic characteristics of the recording film. However, if the Curie temperature is simply lowered, when reading is performed continuously,
The recorded information may be erased.

[Problems to be solved by the invention]

Therefore, not only a method of simply lowering the Curie temperature but also a method with good read stability is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magneto-optical disk having high recording sensitivity without any problem of read stability.

[Means for solving the problem]

In order to solve the above-mentioned problem, an oxygen concentration of 8000 to 1500 is required for forming a recording film of a magneto-optical disk composed of a rare earth-transition metal amorphous alloy film having a columnar structure in a thickness direction.
This is achieved by a method of manufacturing a magneto-optical disk in which a film is formed by a sputtering method using a target of a rare earth-transition metal amorphous alloy of 0 ppm (weight ratio).

FIG. 1 is a schematic sectional view simulating an SEM (scanning electron microscope) photograph of a recording film having a columnar structure.

In the drawing, a state in which a recording film 2 is formed in a columnar structure on a substrate 1 is shown.

[Action]

(1) The present invention utilizes the fact that the density of the recording film is reduced and the thermal conductivity is lowered by forming the recording film into a columnar shape, so that the medium is easily heated and the recording sensitivity can be improved.

(2) In order to form a columnar structure, for example, in sputtering film formation, a method of increasing the gas pressure of Ar used as a sputtering gas or performing sputtering using a gas in which an extremely small amount of oxygen gas is mixed in addition to Ar gas is used. However, the present inventor has found that the same effect can be stably obtained by sputtering using an alloy target with an increased oxygen concentration, and that the columnar structure can be obtained in an oxygen concentration range of 8,000 to 15,000 ppm (weight ratio). That there is
It was revealed by SEM observation.

The reason why the film can be formed on the columnar structure is that the target contains a large amount of oxygen, and the oxygen of the target column is taken into the film during film formation, thereby promoting the formation of the column. It is considered that the same effect as in the case of sputtering by using the mixed gas of the above is obtained. However, when the oxygen concentration of the target is set to 15,000 ppm or more, the formed film is oxidized and the in-plane magnetization component increases, so that good magneto-optical characteristics cannot be obtained.

〔Example〕

(1) Embodiment 1: FIG. 2 is a sectional view of a magneto-optical disk according to an embodiment.

The medium of the magneto-optical disk was produced by a sputtering device. The substrate 1 used was a 5-inch glass substrate 11 on which a photopolymer 12 having a groove 13 for guiding a laser beam was formed.

A 100 nm thick TbFeCo (Tb ₂₁ Fe ₇₁ Co ₈ ) film was used for the recording film 2, and an 80 nm thick SiN film was used for the protective films 3 and 4.

Next, for reference, the following table shows general well-known sputtering conditions for forming a recording film into a columnar structure.

(A) When increasing Ar pressure Ultimate vacuum (Pa) 1 × 10 ^-5 Ar gas pressure (Pa) 1.0 Discharge power (kW) 1.0 or (b) When mixing trace amounts of oxygen with Ar Ultimate vacuum ( Pa) 1 × 10 ^-4 Ar gas pressure (Pa) 0.2 Discharge power (kW) 1.0 Here, a sputtering target with a diameter of 6 inches was used, and discharge power was supplied from a 13.56 MHz frequency rf power supply.

For comparison, a magneto-optical disk was produced with the conventional sputtering conditions, the ultimate vacuum (Pa), 1 × 10 ^-5 Ar gas pressure (Pa), 0.2 discharge power (kW), and 1.0.

(2) Example 2: A TbFeCo alloy, one of RE-TM amorphous alloys, was used as a sputtering target. The oxygen concentration in this alloy target is usually about 2500 ppm,
Using 0000 ppm, a recording film was formed by magnetron sputtering.

The high-concentration oxygen target was prepared by sintering a TbFeCo alloy in oxygen.

This film structure has a columnar structure as shown in FIG.
On the other hand, a target having a normal oxygen concentration does not have a columnar structure.

In the above embodiments, a TbFeCo alloy was used for the recording film or target, but Tb, Gd, D
As long as it is a simple substance of y and Ho or a mixture thereof, Fe, Co or a mixture thereof can be applied as the transition metal.

The average of the above Examples and the recording sensitivity of the Comparative Example are shown in the following table.

Sensitivity of Example (mW) 3.0 Sensitivity of Comparative Example (mW) 4.5 Here, the medium speed was 5 m / s, and the recording sensitivity was a laser power at which the second harmonic of the reproduced waveform was minimized by a spectrum analyzer.

〔The invention's effect〕

As described above, according to the present invention, the recording power is reduced
A magneto-optical disk whose recording sensitivity can be greatly reduced by 35% and a manufacturing method thereof can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view simulating an SEM (scanning electron microscope) photograph of a recording film having a columnar structure, and FIG. 2 is a sectional view of a magneto-optical disk according to an embodiment. In the figure, 1 is a substrate, 11 is a glass substrate, 12 is a photopolymer, 13 is a groove, 2 is a TbFeCo film as a recording film, and 3 and 4 are SiN films as protective films.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Motonobu Mihara 1015 Uedanaka Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Masami Tsutsumi 1015 Kamodanaka Nakahara-ku, Kawasaki City, Kanagawa Fujitsu Limited ( 72) Inventor Eiichi Nakajima 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-60-140706 (JP, A) JP-A-1-118240 (JP, A) JP-A-63-316342 (JP, A) JP-A-63-316340 (JP, A)

Claims (1)

(57) [Claims] In forming a recording film of a magneto-optical disk comprising a rare earth-transition metal amorphous alloy having a columnar structure in a thickness direction, a rare earth-transition metal amorphous having an oxygen concentration of 8,000 to 15,000 ppm (weight ratio). A method of manufacturing a magneto-optical disk, comprising forming a film by a sputtering method using an alloy target.