JP2506696B2 - Optical information recording / reproducing / erasing member - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member capable of recording and erasing information by heating and heating to change the state by irradiation with laser light, and a large-capacity memory optical disk. It can be used in the fields of.

Conventional technology As a member capable of laser recording and erasing using a light-absorbing thin film, a chalcogen compound such as Ge ₁₅ Te ₈₁ Sb is used.
Thin films of ₂ S ₂ , AS ₂ Se _3, etc. are known. Further, a thin film of TbCoFe or the like is known as a magneto-optical material.

When forming an optical disc using these materials, a polycarbonate or PMMA resin substrate is used as the disc substrate. However, any of the thin film materials has a problem that the surface of the resin substrate is easily thermally damaged because the process of irradiation with laser light and the process of heating are used for recording or erasing. On the other hand, a method is known in which an inorganic material thin film layer is provided on the surface of a resin substrate in advance and this is used as a heat resistant layer.
A SiO ₂ material or the like is used as the inorganic material. further,
It is also known that, after forming a thin film which is a recording material, the heat resistant layer is provided on the thin film to prevent thermal damage to the adhesive layer in the structure of adhesion protection.

Each thin film layer can be formed by a method of electron beam evaporation or sputtering.

In any case, it is necessary to successively form a heat-resistant thin layer, a recording material thin layer, a heat-resistant thin layer, and, if necessary, a reflective thin layer.

Problems to be Solved by the Invention When improving the heat resistance of a recording member, the melting point of SiO ₂ etc.
It was necessary to sequentially form a thin film of a dielectric material having a high temperature of 1710 ° C. and a material thin film of a recording material such as Ge ₁₅ Te ₈₁ , Sb ₂ S ₂ .

Therefore, a plurality of materials for the heat-resistant layer and the material for the recording layer are required as the evaporation source, and these are sequentially formed in the same vacuum chamber or in different chambers. There is a problem that it is necessary to prepare a plurality of systems, and the film formation time becomes long because of sequential film formation.

Means to solve the problem In thin film for recording and erasing information, the sputtering thin film forming method is used, and its sputtering target is ZnS, ZnTe, Z with a melting point of 1000 ℃ or more, which has heat resistance.
nSe, SiO ₂ , TiO ₂ , MgO, Al ₂ O ₃ at least one kind of dielectric material as the main component, the melting point of 700 ℃ or less was used to add a light-absorbing recording material component, using both By doing so, a light-absorbing thin film is formed on the substrate.

Action As a sputtering target, a material containing both a highly heat-resistant dielectric material and a light-absorbing recording material component is used. By sputtering this, the dielectric material component and the light-absorbing recording material are deposited on the substrate. To form a heat-resistant material and a light-absorptive recording material simultaneously as a single layer with one evaporation source (sputtering target) in one vacuum chamber in which a thin film containing both components is uniformly formed at one time Will be possible.

Example A material having a melting point of 1000 ° C. or higher is selected as the heat resistant dielectric material. For example, SiO ₂ (Tm = 1710 ° C), ZnS (Tm = 1800
℃), ZnSe (Tm = 1700 ℃), ZnTe (Tm = 1200 ℃), TiO ₂ (T
m = 1820 ℃), MgO (Tm = 2800 ℃), Al ₂ O ₃ (Tm = 2030 ℃)
At least one of the above can be applied.

On the other hand, a material having a melting point of 700 ° C. or less is selected as the light absorbing compound or alloy material. For example, Te (T
m = 449 ℃), Te _1-Y Se _Y (Tm <449 ℃), Sb ₂ Te ₃ (Tm = 622
℃), SnTe (Tm = 696 ℃), InTe (Tm = 696 ℃), Bi ₂ Te ₃ (T
m = 585 ℃), AuTe ₂ (Tm = 464 ℃), Se (Tm = 219 ℃), S (T
m = 119 ℃), Zn (Tm = 419 ℃), In (Tm = 156 ℃), Pb = (T
m = 327 ℃, Ge (Tm = 958 ℃), Sn (Tm = 232 ℃), Bi (Tm
= 271 ° C), Sb (Tm = 630 ° C), etc., at least one is applicable.

Dielectric material is M1, light absorbing material is M2, M1 _1-X M
Prepare each material powder in the form of 2 _X. These powders are mixed and hardened into the shape of a sputtering target. First
The figure shows a conceptual diagram of the cross section of the mixed target. Reference numeral 2 is a high melting point dielectric particle, 3 is a light absorbing material particle, and their mixed target is 1.

A polycarbonate resin plate is used as the substrate. A groove for laser guide is formed on the resin surface. As shown in FIG. 2, the sputtered film 5 is directly formed on the resin substrate 4. This film is composed of a uniform mixture of a high melting point dielectric material component and a light absorbing recording material component. As a condition of the sputtering, Ar gas is used and RF sputtering is performed in a total pressure atmosphere of 100 mTorr or less.

For a recording thin film layer in which a light-absorbing recording material component is uniformly dispersed in a high melting point dielectric material by sputtering, the formed film thickness is set to an appropriate value by utilizing the interference effect on the upper surface and the lower surface of the recording thin film. As shown in FIG. 3, the sputtering film thickness increases the reflectivity of the film from the initial reflectivity level of the substrate due to the interference effect, and the increase of the film thickness decreases the reflectivity to the minimum value. The reflectivity increases again when is increased.

A curve a represents the reflectance at the time of as-depo, and a curve b represents the reflectance after heating and blackening of the state. If heating and quenching with laser light etc. after the heating state change, that part will be as-d again.
It changes to a whitening level close to the epo state. By irradiating a modulated laser beam in a blackened state in advance, information recording of whitened dots can be performed.

In FIG. 2, reference numeral 6 denotes a reflective layer, which can be used to increase the change in reflectance before and after recording.

Effects of the Invention A thin film recording material formed by sputtering from a target in which a high-melting-point dielectric material M1 contains a light-absorbing recording material M2 has the following effects.

(1) The heat resistance of the recording thin film is improved, and a recording member that is not easily damaged by heat can be obtained.

(2) A mixed single-layer film of a heat-resistant component and a recording material component can be formed in a single film forming process, and a recording member can be manufactured in a short time with a single source.

[Brief description of drawings]

FIG. 1 is a sectional view of a sputtering target composed of a high melting point dielectric material component and a light absorbing recording material component of an optical information recording / reproducing / erasing member according to an embodiment of the present invention, and FIG. 2 is a uniform film formed on the same substrate. FIG. 3 is a cross-sectional view of the mixed recording member, showing characteristics of the film thickness dependence of the reflectance of the uniform mixed recording film in the aS-depo state and the film thickness dependence of the reflectance after the change in the heating blackened state. 1 ... mixed target, 2 ... refractory dielectric particles, 3 ...
... Light-absorbing material particles.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuya Akiyama 1006 Kadoma, Kadoma City, Matsushita Electric Industrial Co., Ltd. (72) Inventor Kunihiro Matsubara 1006 Kadoma, Kadoma City, Matsushita Electric Industrial Co., Ltd. (72) Inventor Kazuo Inoue 1006 Kadoma, Kadoma-shi, Kadoma, Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-61-190067 (JP, A) JP-A-61-177286 (JP, A) JP-A-60-219650 (JP, JP-A) A)

Claims (4)

(57) [Claims] 1. A thin film in which information is recorded and erased by being heated by irradiation with light such as a laser to change its state, and a sputtering thin film forming method is used. As a target for the sputtering, ZnS, ZnTe, ZnSe, SiO _{2 is used.} , TiO ₂ , MgO, Al ₂ O ₃
Of at least one of the dielectric materials having a melting point of 1000 ° C. or higher as a main component, to which a light absorbing material component having a melting point of 700 ° C. or less is added, and by sputtering together,
An optical information recording / reproducing / erasing member having a light absorbing thin film formed on a substrate. 2. The light-absorbing material component is Te, Se, S, Zn, In, Pb, G
The optical information recording / reproducing / erasing member according to claim 1, characterized by containing at least one of e, Sn, Bi, and Sb. 3. The optical information recording / reproducing / erasing member according to claim 1, wherein a resin substrate provided with a track for a laser guide is used as a substrate, and a dielectric layer is previously provided on the resin substrate. . 4. A dielectric material component and a light-absorbing thin film uniformly containing a light-absorbing material component are provided, and the thickness of the thin film is the reflectance after laser light irradiation and the reflectance at the time of film formation. The optical information recording / reproducing / erasing member according to claim 1, wherein the difference is selected to be maximum.