JPH0465795B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium, particularly a heat mode information recording medium and a recording method.

Prior Art Heat mode information recording media have the characteristic that the recording medium does not deteriorate due to wear and tear because there is no contact between the medium and the writing or reading head.For this reason, research and development of various heat mode recording media has been carried out. ing.

The heat mode information recording medium can be roughly divided into pit formation type and so-called phase change type.

The phase transition type records information by causing an amorphous-crystalline phase transition in the recording layer of the irradiated area using recording light such as a laser, and detects changes in reflectance with readout light. It is used for reading data.

Most recording media that utilize such a phase transition have a recording layer made of a material containing Te as a main component.

However, in recent years, since Te-based materials are harmful to the human body, research and development using other materials to replace them has been conducted.

Therefore, the present inventors proposed the use of less toxic Ge-Sn based substances instead of Te based substances (patent application).
59-275373). This Ge--Sn-based recording layer can undergo a phase transition or a change in crystal state favorably by recording light. However, the Ge-Sn system is Ge-Sn, which allows stable information recording.
-Sn composition ratio range is relatively narrow.

Purpose of the Invention The purpose of the present invention is to form a recording layer with a new low-toxic substance system instead of the conventional Te-based toxic substance system,
Furthermore, by irradiating this recording layer with recording light, for example, and causing an amorphous-crystalline phase transition or a change in the crystal state in the recording layer in the irradiated area, information can be stably recorded. The objective is to provide a recording medium and a recording method.

DISCLOSURE OF THE INVENTION These objects are achieved by the invention described below.

That is, the first invention is an information recording medium characterized by having a recording layer on a substrate that contains Si and Sn and has an atomic ratio of Sn/(Si+Sn) of 0.05 to 0.95.

Further, the second invention provides an information recording medium having a recording layer on a substrate containing Si and Sn and having an atomic ratio of Sn/(Si+Sn) of 0.05 to 0.95. This is an information recording method characterized by recording by causing a change.

Specific Configuration of the Invention The specific configuration of the present invention will be described in detail below.

The information recording medium of the present invention is formed by depositing a recording layer on a base.

Alternatively, two such devices may be used and integrated with their recording layers facing each other.

Here, the substrate is a flat plate made of glass, resin, or the like. When using light as a recording means, it is preferable to use glass or resin with good light transmittance.

This allows writing, reading, etc. from the back side of the base.

Further, it is preferable that tracking grooves are formed on the recording layer forming surface of the substrate.

A recording layer is provided on the substrate.

The recording layer contains Si and Sn, Sn/(Si+Sn)
The atomic ratio of is 0.05-0.95.

When the atomic ratio of Sn/(Si+Sn) exceeds 0.95, Si
-A recording layer made of Sn is difficult to become amorphous. Therefore, even if heat is applied to the recording layer by, for example, light irradiation, recording cannot be performed due to a change in the crystal state such as an amorphous-crystalline phase transition or a change in grain size.

Furthermore, when the atomic ratio of Sn/(Si+Sn) is smaller than 0.05, the crystallization temperature is high and a lot of energy is required for recording.

In other words, when it is 0.05 or more, the crystallization temperature becomes low and a phase transition state change occurs with less thermal energy during recording, which is preferable in practice. More preferably, when it is 0.15 to 0.7, both crystallization temperature and stability are favorable.

Such a recording layer may be formed using a dry coating method such as a vapor deposition method, a sputtering method, or an ion plating method.

The thickness of the recording layer is approximately 20 nm to 1 μm.

Also, if necessary, between the substrate and the recording layer and/or
Alternatively, various known stabilizing layers, heat absorbing layers, etc. may be provided on the recording layer.

This makes it possible to prevent deterioration of the recording layer and further improve the thermal efficiency for recording.

Furthermore, various protective layers may be provided on the other surface of the base.

To record on an information recording medium having such a recording layer on a substrate, light or thermal energy is applied.

Generally, a semiconductor laser or the like may be used as the recording light.

By irradiating the recording light, an amorphous-crystalline phase transition is caused in the recording layer of the irradiated area, and recording is performed.
That is, recording is performed using phase transition from amorphous to crystalline or from crystalline to amorphous.

Furthermore, in addition to such a phase transition, recording may also be based on a change in crystalline state. Changes in the crystal state include changes in the grain size of microcrystals, types of crystal forms, orientation, and crystallinity.

Reading after recording may be performed by irradiating reading light or detecting a change in the reflectance of the recording layer.

In such a case, at a wavelength of 830 nm, the reflectance, which is about 40% in an amorphous state, changes by about 5 to 40% due to crystallization.

In this way, since a relatively large change in reflectance can be obtained, the quality of recording characteristics such as writing and reading is stable.

Specific Effects of the Invention The information recording medium of the present invention is formed from a Si-Sn based material.

When this recording layer is irradiated with recording light or the like, an amorphous-crystalline phase transition or a change in crystal state occurs in the recording layer in the irradiated portion. Therefore, by utilizing this phenomenon, information can be recorded.

Therefore, compared to the conventional Te-based hazardous substance system,
A medium with lower toxicity and equivalent recording properties will be realized.
Furthermore, the medium of the present invention has better weather resistance than Te.

Moreover, the Si-Sn composition ratio range in which information can be stably recorded is relatively wide, the S/N ratio for reading is high, and quality stability is excellent.

Specific Examples of the Invention Hereinafter, the present invention will be explained in further detail by giving examples of the present invention.

Example A thin film layer made of Si--Sn was deposited on a glass substrate to a thickness of 180 nm by sputtering to form a recording layer.

The atomic ratio of Sn/(Si+Sn) in the recording layer was 0.32 as measured by XPS.

In addition, after depositing this Si-Sn recording layer and 200
After annealing for 10 minutes at ℃, X-ray diffraction was performed and Si-
The amorphous-crystalline phase transition of Sn was confirmed.

The results of X-ray diffraction immediately after layer formation are shown in Figure 1, and the results after annealing are shown in Figure 2.

Furthermore, FIG. 3 shows the relationship between annealing temperature and reflectance at a wavelength of 830 nm.

From FIG. 3, it can be seen that the reflectance at 830 nm changes by about 40% from the state immediately after layer formation due to phase transition.

Apart from this, as a comparison, as above,
When a layer was formed with a composition in which the atomic ratio of Sn/(Si+Sn) was 0.99, Si-Sn did not become amorphous but was already crystallized, and no phase transition occurred.

Furthermore, in the same manner as above, when a layer was formed with an atomic ratio of Sn/(Si+Sn) of 0.01, it was confirmed that with this composition, the layer was amorphous both immediately after the layer was formed and after annealing at 300°C.

In addition, according to the above, samples of each composition were layered and their crystallization temperatures were measured. The results are shown in Figure 4.

From FIG. 4, it can be seen that when Sn/(Si+Sn) exceeds 0.95, it does not become amorphous, and when it is less than 0.05, it remains amorphous even after annealing at 400°C.

Furthermore, when the sample of the present invention was recorded with an 830 nm semiconductor laser and reproduced with an 830 nm semiconductor laser, good recording and reproduction could be performed.

Note that recording and reproduction could not be performed with Sn/(Si+Sn)=0.01 and 0.99.

[Brief explanation of the drawing]

1 and 2 respectively show the Si-
This is a chart of X-ray diffraction immediately after the formation of the Sn recording layer and after annealing. Figure 3 shows the Si of this invention.
3 is a graph showing changes in reflectance immediately after the -Sn recording layer is deposited and depending on annealing temperature. Figure 4 shows
It is a graph showing the relationship between Sn/(Si+Sn) and crystallization temperature.

Claims (1)

[Scope of Claims] 1. An information recording medium comprising a recording layer on a substrate that contains Si and Sn and has an atomic ratio of Sn/(Si+Sn) of 0.05 to 0.95. 2 Recording is performed by causing an amorphous-crystalline phase transition or a change in the crystalline state in an information recording medium that has a recording layer on a substrate that contains Si and Sn and has an atomic ratio of Sn/(Si+Sn) of 0.05 to 0.95. An information recording method characterized by: