JPH02108259A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain satisfactory C/N even during long-term use by providing a recording layer and specified protective layers on a substrate. CONSTITUTION:This recording medium is formed by providing the recording layer 2 on the substrate 1 and the protective layers 3 and 4 on the recording layer 2. An Si-Al-O-N-X film is used for at least one of the protective layers 3 and 4. At least one kind among Ti, Zr and B are used for X. The magneto- optical recording medium the C/N of which exhibits a satisfactory value even after the long-term use is obtd. in such a manner. The performance which is excellent in Kerr-enhancement effect is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical information recording medium, and more particularly to an improvement of a protective layer of an optical information recording medium.

[Prior Art] Generally, among optical information recording media, magneto-optical recording media have a protective layer formed thereon to improve the corrosion resistance of the recording layer. Because they are often made of materials that are easily oxidized,
Many attempts are made to improve corrosion resistance by adopting a structure in which the upper and lower surfaces of the recording layer are sandwiched between protective layers.

FIG. 1 is a cross-sectional view showing the layer structure of such a magneto-optical recording medium. In the figure, 1 is a substrate, 2 and 4 are protective layers, and 3 is a recording layer.

As a material for the protective layers 2 and 4 in such a 4R structure, for example, a material using S1-Al1-0-N has been tried in the past.

[Problems to be Solved by the Invention] However, although the optical information recording medium using the above-mentioned 5t-AX-0-N film as a protective layer has good initial performance, it is insufficient to withstand long-term use. Corrosion resistance has not yet been achieved, and in particular, C/N may no longer show a satisfactory value after long-term use, so it has not yet reached a practical level.

An object of the present invention is to provide an optical information recording medium that exhibits a satisfactory C/N ratio even during long-term use and has excellent long-term reliability.

[Means for Solving the Problems] The gist of the present invention is to provide an optical information recording medium having a recording layer and at least one or more protective layers on a substrate, at least one of the at least one or more protective layers. ．． mS 1
-AQ, -0-N-X (X is Ti.

It exists in an optical information recording medium characterized by using a film of at least one of Zr and B.

Below, the configuration of the present invention will be explained in detail.

(Layer structure) The layer structure of the F1 recording medium according to the present invention is particularly limited. It may have a layer structure as shown in Figure 1, or it may have only one protective layer, or it may have three or more protective layers.
It may be something that

(Protection j", ji) JgL containing Ti, Zr, and B is not particularly limited. Also, only one element among Ti, Zr, and B may be contained, and 2f!i type Contains more than 3 elements
] Is it okay to go? U-dou・Two! ′! For optical information recording media having a protective layer, all five protective layers contain Ti, Zr,
A protective layer containing one of the elements of B may be used, or only T may be used for the protective layer of ~.

(Recording Layer) The recording layer has the function of a recording layer for an optical information recording medium, and is generally 6L for use. For example, in the case of a magneto-optical recording medium, T b -F e
, T h -F e -Co,, T b -Ct
>, Ga--Tb Co, etc. can be used.

[Function] According to the present invention, S1-An-0-N-X (X
By using a film (at least one of Tj, Zr, and B) as a protective layer, it is possible to obtain a magneto-optical recording medium that exhibits a satisfactory C/N ratio even after long-term use. The long-term durability of the magneto-optical recording medium can be significantly improved.

Furthermore, according to the magneto-optical recording medium V of the present invention, since the refractive index is increased, excellent performance equivalent to or better than that of the conventional magneto-optical recording medium can be obtained even though the Kerr enhancement effect is reduced. For long-term use1. The reason why it is possible to obtain an optical recording medium that exhibits a satisfactory C/N ratio is as follows.
Although the details have not yet been elucidated, it is thought that this is due to the poor corrosion resistance of the material of the protective layer and the small internal stress of the protective layer.

[Embodiment] Hereinafter, a case of an optical 611 disk will be described as an example of an uninvented embodiment. .

First, optical iJ and 1Q disks each having a protective layer formed of a material having the composition shown in Table 1 were prepared. In Table 1, B to E are magneto-optical disks according to the present invention, and A is a conventional magneto-optical disk prepared for comparison. Moreover, the composition ratio of the protective layer of each sample was measured using an electron probe microanalyzer. Next, we measured the Kerr rotation angle and C/N ratio as the initial performance of each optical tin disk, and also measured the C/N ratio when left under high temperature and high humidity as a corrosion resistance test.
Changes in the ratio over time were measured.

In each of the magneto-optical disks in Table 1, a polycarbonate substrate was used as the substrate, and a Tb--Fe--Co alloy film was used as the recording layer. The thickness of the recording layer is 800, and the thickness of the protective layer is the thickness that maximizes the Kerr rotation angle of the recording layer, that is, the thickness that provides the best Kerr enhancement effect!
2:3, and a sputtering method was used to form the recording layer and the protective layer. The layer structure was the same as in Figure 1.

(1) Initial performance The measurement results of Kerr rotation angle and C/N ratio as initial performance are shown in Table 2. Here, the Kerr rotation angle is at a wavelength of 830 nm.
It was measured using a semiconductor laser, and expressed as a ratio when the Kerr rotation angle of sample A was set to 1.00. Further, the C/N ratio was measured by rotating each sample at a linear velocity of 2.5 m/s and recording and reproducing an IMHz signal.

Table 2 As can be seen from Table 2, the magneto-optical disk according to the present invention is
It has an initial performance of (lFt) higher than conventional magneto-optical disks.

(2) Long-term performance Next, samples A-E were left in a thermostatic oven set at 65°C and 95% RH, and the C/N of the recording/reproduction signal was
The ratio was measured. As in the case of measuring the initial performance, the C/N ratio is the value obtained when each sample is rotated at a linear velocity of 2.5 m/s and an IMHz signal is recorded and reproduced.

The results are shown in Figure 2.

As is clear from Fig. 2, the magneto-optical disk (sample A) using the 5t-Aβ-〇-N film as a protective layer has 10
The C/N ratio rapidly decreases from around 00 hours onwards. On the other hand, in the magneto-optical disk of the present invention (samples B-E), the variation in C/N ratio was ±2 dB or less even after too much time had elapsed.

From this, it was found that according to the present invention, it is possible to obtain a magneto-optical disk with better long-term reliability than the conventional one.

[Effects of the Invention] As explained above, the present invention provides an optical information recording medium in which the C/N ratio does not decrease even after long-term use, that is, an optical information recording medium with excellent long-term reliability. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of the layer structure of an optical information recording medium;
FIG. 2 is a diagram showing the change over time in the C/N ratio of an optical information recording medium under high temperature and high humidity. 1... Substrate, 2.4... Protective layer, 3... Recording layer. Figure 1 Figure 2 Patent applicant Hiroshi Sekisui Chemical Co., Ltd. Representative 1) Kaorutoki n+l (holJr)

Claims (1)

[Claims] In an optical information recording medium having a recording layer and at least one or more protective layers on a substrate, at least one of the at least one or more protective layers has Si-Al-O-N-X (X is Ti, Zr, or B). An optical information recording medium characterized by using at least one type of film.