JPS62208441A - Recording medium for rewriting type optical disk - Google Patents

Abstract

PURPOSE:To prevent the deterioration in recording and erasing characteristics and recording life by constituting an optical recording layer of an alloy film essentially consisting of Te and Au and contg. at least one kind of element selected from an element group consisting of Se, As, Sb and S. CONSTITUTION:A transparent substrate 1 consists of glass or plastic and is provided with an underlying layer 2 consisting of a transparent vapor deposited SiO film, the recording layer 3 and protective layer consisting of a transparent vapor deposited SiO film. The optical recording layer 3 consists of the alloy element essentially consisting of Te and Au and contg. at least one kind of the element selected from the element group consisting of Se, As, Sb, S. The alloy film contains the essential components Te and Au at 2.0<=Te/Au<=20.0 by number of atom and contains at least one kind of the additive element selected from the element group consisting of Se, As, Sb and S in a 50-5at% content range in addition to the Te and Au.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a laser recording medium on which recording is performed by irradiating a laser beam to cause an optical change in the irradiated area, and particularly relates to a rewritable laser recording medium. The present invention relates to a recording medium for a rewritable optical disc.

[Conventional technology]

Conventionally, information is recorded using a laser beam, and it is used as a so-called write-once optical recording medium.

On the other hand, rewritable optical recording media utilize crystal-amorphous phase transition. Ternary alloy thin films containing Tc and Sn as main components, to which Se, Ge, Ga, As, etc. are added are known. In these phase change optical recording media,
The recording film is irradiated with laser light, melted, and then rapidly cooled to form amorphous pits that correspond to the recording state. On the other hand, erasing is performed by irradiating the pits with long pulsed light having a lower power density than during writing, annealing the pits below the melting point of the alloy film, and recrystallizing (erasing) the pits.

[Problems to be solved by the invention] In conventional optical recording media, a more stable intermetallic compound is created by repeating amorphization and crystallization, and since this has a high melting point, it is difficult to melt it again with laser light. It's difficult. for example,
Conventional TeSn has a temperature of 790°C.

The melting point of Te is 450°C, while it is 725°C for TeGe.
Therefore, it has a melting point about 300° higher.

The above-mentioned precipitation of the high melting point substance increases with the number of repeated writing/erasing operations, and eventually results in large compositional unevenness, which poses a problem of adversely affecting the writing/erasing characteristics and the lifespan of the recorded pits.

[Means for solving problems]

The present invention solves the conventional problems, does not have the disadvantage of precipitation of high-melting-point intermetallic compounds, and has a rewritable optical disk that maintains a stable recording state that can be erased by irradiation with short erasing laser pulse light. The present invention provides a recording medium for a rewritable optical disc comprising an optical recording layer on a transparent substrate, wherein the optical recording layer has Te and Au as main components, and S e * A S, s. b. The optical recording layer is characterized by being composed of an alloy film containing at least one element selected from the group of elements 3, and in particular, the optical recording layer contains '' as a main component.
"e (!l: A u content is 2.0' in atomic ratio
- Consisting of an alloy film with T e / A u <20.0,
In addition to Te and Au, the main components are Se, As, and S.
The alloy film is characterized by comprising an alloy film containing at least one additional element selected from the group of elements b, sulfur, and sulfur in a content range of 50 to 5 at%.

[For production]

The present invention provides a rewritable optical recording medium (hereinafter referred to as a recording medium) in which an optical recording layer (hereinafter referred to as a recording layer) has T.
The most important feature is that e is mainly used and Au is used as a metal additive.

The conventional technology uses Sn as the main metal additive, but this is different.

Fig. 2 shows the phase diagram of T e -A u, and when the Au content is between 33 and Oat%, T e
When the US alloy is annealed below 416°C, Te
and AuTe2 are precipitated. The melting point of these is 450℃
, 464° C., and can be easily melted by laser beam irradiation. Therefore, the recording pits return to the same state every time, so there is no deterioration in recording/erasing characteristics and recording life even after writing and erasing many times.

Examples will be described below.

〔Example〕

FIG. 1 is a sectional view of a recording medium illustrating a first embodiment of the present invention, where l is a transparent substrate made of glass or plastic, and in this embodiment, a glass substrate with a thickness of 1.2 mm; 2 is a base layer made of a transparent SiO vapor deposited film with a thickness of 1100 nm, and 3 is a recording layer with a thickness of 85 nm, T e 55.
An alloy thin film having a composition of A u 15 S e 3° was prepared by a multi-component vacuum evaporation method.

4 is a protective layer made of a transparent SiO vapor deposited film with a thickness of 300 nm. After heating and crystallizing this in an oven at 200°C for 1 hour, a semiconductor laser beam with a wavelength of 830 nm is focused into a spot with a diameter of 1.5 μmφ using a lens with an aperture ratio of 5.0, and is applied to the recording layer 3 from the glass substrate 1 side. We irradiated it and conducted recording/erasing experiments.

Amorphization occurred at a laser power of 8 mW and a pulse width of 200 ns on the recording medium. By irradiating this with continuous wave light with a laser power of 0.3 mW, it was possible to read the recorded information. Note that no change was observed in the recording status during this time. Recorded pits could be erased under the conditions of a laser power of 5 mW and a pulse width of 1 μs.

Furthermore, when recording and erasing were repeated 107 times under the same conditions, no change was observed in the recorded state.

Furthermore, since the recorded state (amorphous state) on this medium after writing and erasing 107 times is stable at 40°C for more than - years, the amorphous life, that is, the recording life, is sufficiently stable at room temperature. I found out something.

As another example, the recording layer 3 is made of Te6oAu15Cu.
An alloy thin film having a composition of sA s20 was used. This was fabricated using a multidimensional vacuum evaporation method. This recording medium exhibited almost the same characteristics as the previous example. Furthermore, we fabricated a recording medium with a recording layer made of an alloy thin film containing sb and s as additive elements with the same composition, and observed the recording and erasing characteristics. As a result, almost the same characteristics were confirmed. It was done.

In the composition of Te1-3:Aux in the present invention, the added content of Au is between 33% and 0%, and 2.0% of Te
By configuring the atomic ratio within the range of /Au<20.0, no high melting point substance is precipitated during the crystallization process (erasing process by laser beam).

Furthermore, by adding at least one third element selected from the group of elements Se, As, Sb, and S, the stability of the amorphous value of the alloy film can be increased, and the stability of the high melting point material can be increased. A preferable addition range is 5 to 50 at% as a condition for no precipitation. The stability as an amorphous state is insufficient with only the Te-Au binary.

Furthermore, G (!, Ga, In, Cu, Si.

By adding at least one fourth element selected from the group of elements ACPd, PC, and Ag in an extremely small amount of 5 aL % or less, the stability as an amorphous state and the erasing property are improved.

〔Effect of the invention〕

As explained above, the recording layer of the recording medium of the present invention has Tc
By using a multi-component alloy system using Au as the main metal additive, writing and erasing can be performed multiple times, and rapid crystallization is possible in a stable recording state, which is highly effective.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of a recording medium according to an embodiment of the present invention, and FIG. 2 is a phase diagram of Te-Au. 1... Glass substrate, 2... Base layer, 3... Recording layer, 4... Protective layer! ! Bait ・0

Claims (3)

[Claims] (1) In a recording medium for a rewritable optical disc comprising an optical recording layer on a transparent substrate, the optical recording layer has Te and Au as main components and is selected from the element group Se, As, Sb, and S. 1. A recording medium for a rewritable optical disc, comprising an alloy film containing at least one element. (2) The optical recording layer is made of an alloy film having a content of Te and Au as main components in an atomic ratio of 2.0≦Te/Au≦20.0. A recording medium for a rewritable optical disc as described in . (3) The optical recording layer has Te and Au as main components.
Claim 1, characterized in that it is made of an alloy film containing at least one additional element selected from the element group Se, As, Sb, and S in a content range of 50 to 5 at%. A recording medium for a rewritable optical disc as described in .