JP2765095B2 - Optical memory - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical storage device used for audio equipment, computer peripheral equipment, and the like.

(Prior Art) In recent years, a compact disk (hereinafter, abbreviated as CD), which is one of optical storage media, has been widely used. As an applied technology of this CD, CD-ROM which recorded computer data on CD
The use of these read-only optical disks is desired to have higher storage stability at high temperature and high humidity than ever before.

2. Description of the Related Art Conventionally, an optical memory body has a structure in which a reflective film made of aluminum, gold, or the like is formed on a base body made of a polycarbonate resin or the like, and a protective film such as a resin is coated on the reflective film. However, polycarbonate resins and other materials have drawbacks such as poor corrosion resistance.To solve this problem, an optical memory using glass with high reliability and long life as the substrate material, utilizing the high corrosion resistance of glass, was reported. (Eg, Toge, Matsuda, Minami: Journal of the Ceramic Society of Japan, Vol. 95, 1987
Year, p. 182).

However, since it is difficult to provide irregularities for recording information on glass, a ceramic thin film (hereinafter abbreviated as sol-gel film) by a sol-gel method has recently been provided as a base on a substrate. There has been reported an optical storage body having a sol-gel film provided with uneven pits for recording information or unevenness for guiding a light beam for recording / reproducing.
(For example, N.TOGE, A.MATSUDA, T.MINAMI, Y.MATSUNO, S.KAT
AYAMA, Y.IKEDA: Journal of Non-Crystalline Solids, v
ol.100, (1988) pp501) (Problems to be Solved by the Invention) However, in the conventional technique, a solvent, a catalyst, water for hydrolysis and the like evaporate on the assumption that a ceramic thin film is fired by a sol-gel method. Therefore, continuous pores of 1 to 5 nm are generated in the sol-gel film. The sol-gel film calcined at a low temperature of about 300 ° C. reversibly adsorbs and desorbs water in the continuous pores with a change in humidity, resulting in a change in volume.
When a high-temperature and high-humidity test is performed, the volume change of the sol-gel film becomes remarkable, the adhesive force between the sol-gel film and the reflective film decreases, and peeling occurs between the sol-gel film and the reflective film. This causes a serious problem of causing an error in the optical storage medium.

The present invention has been made in view of the above-described conventional circumstances, and alleviates deformation of a sol-gel film by employing a reflective film having a high Young's modulus or hardness, thereby reducing the deformation of the sol-gel film. It is an object of the present invention to provide an optical memory element that reduces the change with time of the adhesive force between the reflective films and achieves high reliability and long life.

(Means for Solving the Problems) The present invention is directed to an optical memory body in which a reflective film coated on the base and a contradictory film coated on the reflective film are sequentially formed on a substrate. The base body is a ceramic thin film formed by a sol-gel method, and the reflective film is an optical recording medium characterized by containing at least one of platinum, iridium, rhodium, osmium, and ruthenium. is there.

 The optical memory of the present invention is manufactured, for example, as follows.

First, for example, a tempered glass, a tempered glass coated with silicon oxide, titanium oxide, silicon nitride, or the like, or a substrate such as quartz glass, is coated with Si, Ge, T
Oxides such as i, Zr, Hf, Ta, Sn, etc., nitrides, or a mixture thereof are used. The sol-gel film has a guide groove and a pit in which information is written.

Next, on the base material, as a reflective film, a material containing at least one of platinum, iridium, rhodium, osmium, or ruthenium is used as a high-frequency magnetron sputtering method, an ion plating method, a plasma CVD method.
It is coated with a film thickness of 10 to 500 nm by a method, a vacuum deposition method or the like.

Further, if necessary, a protective film made of various oxides, nitrides, resins, or the like is formed on the reflective film, thereby obtaining the optical memory of the present invention.

(Action) At least platinum, iridium, rhodium, osmium,
Alternatively, a reflective film containing at least one kind of ruthenium has high Young's modulus and hardness, and is excellent in corrosion resistance. For this reason, the deformation of the sol-gel film due to a change in humidity is suppressed, and there is almost no change in the adhesive force between the sol-gel film and the reflection film over time. Therefore, the reflective film does not peel off from the base body of the sol-gel film, and the reflective film does not peel off from the highly reliable optical memory body, so that a highly reliable optical memory body can be obtained.

(Example) Hereinafter, the present invention will be described in detail with reference to tables and drawings.

On a base of a sol-gel film of the material shown in Table 1 formed on a glass substrate, a reflective film having a composition shown in
0 nm was formed. Next, a protective film made of the material shown in Table 1 was formed on the reflective film to produce five optical storage media.

FIG. 1 is a partial cross-sectional view showing one embodiment of the optical storage body manufactured as described above. In the figure, 1 is a base body, 2 is a reflective film, and 3 is a protective film.

The sample prepared for comparison is exactly the same as the optical storage medium of the example except that a reflective film was made of gold.

A conventional product for comparison is an optical storage element in which a reflective film made of aluminum is formed on a base body made of a polycarbonate resin having bits, and a protective film of resin is coated on the reflective film.

Next, the samples of these examples, the sample of the comparative example, and the conventional product were subjected to an environmental resistance test at a temperature of 120 ° C. and a relative humidity of 90% for one month, and an error rate as an index of signal quality was measured. . Table 2 shows the results.

As shown in Table 2, the error rate of each sample was 5 × 10 ⁻⁵ at the initial ^stage , but after one month of the environmental resistance test, the error rate of the sample of the present invention showed some deterioration. However, the comparative example, the sample, and the conventional product were so good that they could not be compared. The error in the comparative example was due to the peeling of the gold reflective film, and the error of the conventional product was found by microscopic observation to be due to the peeling and corrosion of the aluminum reflective film.

Although the present invention has been described with respect to a read-only optical disk, it is apparent that the present invention can be applied to a rewritable optical disk such as a magneto-optical disk or a phase change optical disk and an additional write optical disk.

(Effects of the Invention) As described above in detail, the optical memory of the present invention is formed by forming a material containing at least one of platinum, iridium, rhodium, osmium, and ruthenium as a reflective film. The adhesive composition of the present invention has a reduced change in the adhesive force between the reflective film and the base body of the sol-gel film with time, and also has excellent corrosion resistance, and has much higher reliability than the comparative example and the conventional product.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing one embodiment of the optical storage body of the present invention. 1. sol with guide grooves and pits with written information
Underlayer of gel film, 2 ... reflective film, 3 ... protective film.

Claims (1)

(57) [Claims] 1. An optical storage element comprising: a substrate, a base, a reflection film coated on the base, and a protective film coated on the reflection film, sequentially formed on the substrate, The base body is
An optical recording medium, which is a ceramic thin film formed by a sol-gel method, wherein the reflective film contains at least one of platinum, iridium, rhodium, osmium, and ruthenium.