Phase-change optical recording medium

Abstract

A phase-change optical recording medium has a phase-change recording film to which recording and erasure can be reversibly performed by irradiation with light, and at least one dielectric film formed of a SiOC film containing Si, O and C, and having a carbon concentration within a range of between 0.1 and 30 atomic %.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2003-189670, filed Jul. 1, 2003, the entire contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a phase-change optical recording medium for recording information by reversibly changing the state of a recording film by irradiation with a light beam, more particularly, to a phase-change optical recording medium in which atomic arrangement of the recording film is changed between an amorphous state and a crystalline state. [0004] 2. Description of the Related Art [0005] The principle of recording, erasure and reproduction in a phase-change optical recording medium is as follows. When a portion of a phase-change recording film is heated by irradiation with light to a temperature higher than the melting point thereof, the heated po...

AI Technical Summary

Benefits of technology

The present invention provides a phase-change optical recording medium with high recording density that can suppress cross-erase even when track pitch is reduced. This is achieved by using a recording film that can reversibly perform recording and erasure by irradiation with light, and a dielectric film made of a SiOC film containing silicon, oxygen, and carbon. The carbon concentration in the SiOC film is between 0.1 and 30 atomic%.

Problems solved by technology

When signals with low amplitude are converted into digital data, errors are likely to be generated.

Where the track pitch is reduced to a level substantially equal to or smaller than the beam size, however, this approach would bring about a problem of the so-called “cross-erase”, that is, the information recorded in a certain track would be deteriorated in a process of writing or erasure in the adjacent tracks.

However, it cannot be expected to optically reduce the beam size further, as far as visible light is used.

However, various problems are left unsolved in the optical recording medium using the near-field light and, thus, such a medium has not yet entered the stage of the practical application.

One of the causes is that, when an adjacent track to a track in question is irradiated with a laser beam, the foot portion of the laser beam overlapping the track in question has a considerably high intensity, with the result that the recording mark in that track is deteriorated by only the effect of the light application.

Another cause is that, when an adjacent track to a track in question is heated by a laser beam, the generated heat is conducted to the track in question by heat transfer in the in-plane direction, with the result that the shape of the recording mark in that track is deteriorated under the thermal effect.

However, if the heat control film is excessively thin, the heat transfer to the reflection film is caused simultaneously with heating the recording film by a laser beam in the recording process.

As a result, temperature elevation of the recording film is rendered insufficient and, thus, a region that is heated to reach the melting point is made small so as to give rise to a problem that it is impossible to form a recording mark having a desired area.

It should also be noted that, in the erasure process, the recording film is cooled simultaneously with the heating, with the result that the time period during which the recording film is retained within a temperature range in which the recording film can be crystallized is rendered insufficient.

Thus, it is difficult to crystallize the recording mark so as to give rise to a problem that an erasure rate (erase rate or erasability) is markedly lowered.

However, the in-plane heat transfer is promoted so as to cause the cross-erase problem easily.

In addition, the cooling rate of the recording film is lowered, which causes the region that has been melted in the recording process to be recrystallized without being made amorphous, with the result that the mark formed is rendered excessively small.

In this prior art, however, since the intermediate film uses a material having low thermal conductivity, it is difficult to rapidly cool the recording film, resulting in failure to produce a sufficient effect of suppressing the cross-erase.

However, the conventional techniques were incapable of solving simultaneously all the problems including the sensitivity of the recording power, the cross-erase, the recrystallization and the erasure rate.

However, the cross-erase is not studied in this prior art.

It should be noted that it is impossible to achieve good recording characteristics and to suppress the cross-erase simultaneously by simply cooling the recording film.

However, the cross-erase is not studied also in this prior art.

Since the main purpose of this prior art is to improve overwrite characteristics by simply cooling the recording film and suppressing the thermal damage, it is impossible to suppress the cross-erase problem in this prior art.

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