JPH0377576B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical information recording medium that records and reproduces information by irradiating it with an energy beam such as a laser beam.

[Summary of the invention]

The present invention provides an optical information recording medium comprising a substrate and a recording layer made of a crystalline material formed on the substrate, wherein the recording layer contains at least one of carbon, hydrogen, nitrogen, or fluorine. Formed from tellurium (Te) or its combination, the recording layer is irradiated with an energy beam such as a laser beam, and information is recorded by growing crystal grains in the recording layer without forming holes or other deformed parts. This makes it possible to realize a high-density and highly reliable optical information recording medium.

[Conventional technology]

2. Description of the Related Art In recent years, devices for recording or reproducing information on optical information recording media, particularly optical discs, have been commercialized. Among these types of devices, DRAW (Direct
Those using Read After Write (Read After Write) disks are attracting particular attention. Various proposals have been made regarding materials for such discs and methods for recording and reproducing them.

JP-A Nos. 58-9231, 58-9233, and 58-9234 disclose that a recording layer made of a low-melting metal containing carbon, nitrogen, hydrogen, fluorine, etc. is irradiated with an energy beam, It has been proposed to record information by melting or vaporizing the area irradiated with an energy beam, creating a hole or at least deforming it into a concave shape.

[Problems to be solved by the invention] However, in the above method, there are relatively few problems when the hole sizes are approximately the same, but when the hole sizes change randomly, There was a problem in that the shapes of the holes tended to be irregular, making it difficult to form the holes stably. Therefore, it is conceivable to form a space above the recording layer so that the melting and evaporation of the low melting point metal is not hindered so that the holes are formed in a relatively stable state. However, using this so-called air sandwich structure not only increases the overall thickness of the disk, but also imposes stricter structural restrictions such as sealing, and also makes it more likely to warp or deform. This method had the disadvantage of requiring strict quality control, etc., as problems occurred.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an example of the optical information recording medium of the present invention.

In the figure, 1 is a substrate made of acrylic resin, on which grooves (guide grooves) are formed by injection molding. The substrate 1 can also be constructed of, for example, a plastic substrate or a glass substrate provided with grooves made of ultraviolet curable resin. The thickness can be arbitrarily set as required, and can be set to about 1 to 2 mm, for example.

2 is a recording layer on which information is recorded, and is formed on the substrate 1. The thickness of the recording layer 2 is, for example, 100
Although the thickness is appropriately selected from the range of Å to 1 μm, the thickness can be relatively thick, for example, 1000 Å or more in order to prevent the formation of deformed parts such as holes.

Examples of the material for forming the recording layer 2 include tellurium (Te) containing at least one of carbon, hydrogen, nitrogen, and fluorine, or a combination thereof.
Here, the tellurium (Te) complex is composed of other low melting point metal elements such as bismuth, zinc, cadmium,
It may contain at least one of indium, antimony, lead, tin, selenium, arsenic, germanium, and aluminum, or an alloy thereof. Considering thin film molding technology and sensitivity,
Among these metals or alloys whose melting point is 25℃~
A temperature of 700°C is preferred.

The recording layer 2 targets these metals,
For example, methane (CH ₄ ) gas, nitrogen (N ₂ ) gas,
It can be formed by sputtering in hydrogen (H ₂ ) gas, carbon tetrafluoride (CF ₄ ) gas, argon (Ar) gas, or a mixed gas thereof.

CH ₄ /Ar value from 0.75 to 1.25, gas partial pressure from 1 to
A recording layer 2 with a thickness of 1000 Å or more was formed using a tellurium (Te) target at 1000 Pa, a gas flow rate of 10 to 100 c.c./min, and a sputter output power of 50 to 1000 W. When this recording layer 2 was analyzed for the structural state of the content of recording layer forming elements by Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), it was found that carbon is graphite, hydrocarbon, or tellurium (Te ) was confirmed to be in a bonded state with the carbide.

Similarly, when the recording layer 2 was formed using a tellurium (Te) alloy target containing 5 atomic % of antimony (Sb) instead of the tellurium (Te) target, carbon Tellurium (Te) and antimony (Sb)
It was in a bonded state with the carbide of the alloy.

An X-ray diffraction diagram of the recording layer 2 thus formed is shown in FIG. 3a. It can be seen from the figure that the recording layer 2 is already crystalline. Further, FIGS. 3b, 3c, and 3d show that the recording layer 2 was heated at 50°C, 100°C,
It shows the X-ray diffraction diagram when each sample was heated at 200°C for 5 minutes in an electric furnace. In other words, it can be seen that as the temperature is raised, the crystallinity increases.

Moreover, FIG. 4 is a plot of changes in the reflectance of the recording layer 2 with respect to temperature changes and changes in crystal grain size determined by analyzing the X-ray diffraction pattern. As is clear from this figure, both the crystal grain size and the reflectance increase as the temperature rises. The diameter of the crystal grains is considered to be in a practical range, for example, from 10 Å to 1 μm, from the viewpoint of obtaining an appropriate change in reflectance and recording density.

From the above, it can be seen that if the recording layer 2 is heated locally by irradiating it with an energy beam such as a laser beam, the reflectance of that portion increases, and thereby information can be recorded and reproduced.

If information is to be recorded and reproduced by changes in reflectance, unlike the case where deformed parts such as holes are formed, there is no need to use an air sandwich structure. It is preferable that a protective film 3 is formed on the surface of the film to prevent the formation of deformed portions even when a particularly strong energy beam is irradiated. The protective film 3 can be formed of an organic or inorganic material, such as an ultraviolet curable resin, a thermoplastic resin,
Transparent materials such as thermosetting resins, silicon dioxide, (SiO ₂ ), and magnesium fluoride (MgF ₂ ) are suitable. In actual practice, I applied an ultraviolet curable resin with a pencil hardness of 6H or more after curing to a thickness of 1 μm or more.

In this way, in an optical information recording medium comprising a substrate 1, a recording layer 2 made of a crystalline material formed on the substrate 1, and a protective film 3 formed on the recording layer 2 as necessary, records information by irradiating the recording layer 2 with an energy beam such as a laser beam through the protective film 3 or the substrate 1 and growing the crystal grains of the recording layer 2 without forming deformed parts such as holes. Then, it is possible to reproduce the recorded information by using the change in reflectance that occurs as a result of being irradiated with the energy beam, and at 1MHz it is possible to reproduce the recorded information.
A CN ratio of 50dB (bandwidth 30kHz) and an error rate of 1×10 ^-5 or less can be obtained.

[Effects of the Invention] As detailed above, the present invention provides an optical information recording medium comprising a substrate and a recording layer made of a crystalline material formed on the substrate.
A recording layer made of a crystalline material is formed by forming a recording layer of tellurium (Te) containing at least one of carbon, hydrogen, nitrogen, or fluorine or a combination thereof, and irradiating the recording layer with an energy beam. Information is recorded by growing and increasing the crystal grains in the layer, so there is no need for a complicated structure like the air sandwich structure, and even if the pit length changes randomly, it is less likely to cause irregularities. , there are fewer restrictions on the data signal modulation method, and a high-density, highly reliable optical information recording medium can be realized at low cost. Furthermore, since oxygen or oxides are not present in the recording medium, the stability of the recording medium is increased and its lifespan can be extended.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
The figure is a sectional view showing another embodiment, and FIG.
The line diffraction diagram, FIG. 4, is a characteristic diagram of reflectance and crystal grain size. 1... Substrate, 2... Recording layer, 3... Protective film.

Claims (1)

[Claims] 1. An optical information recording medium comprising a substrate and a recording layer made of a crystalline material formed on the substrate, in which the recording layer contains at least one of carbon, hydrogen, nitrogen, or fluorine. 1. An optical information recording medium formed of tellurium (Te) or a combination thereof, wherein information is recorded by growing crystal grains of the recording layer by irradiating the recording layer with an energy beam.