JPH01211337A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To improve the recording sensitivity even of a plastic substrate by forming an underlying layer of a thin carbon film. CONSTITUTION:The underlying layer is formed of the thin carbon film. This film can be formed by a vacuum deposition method, sputtering method, ion plating method, etc. The two layers of the underlying layer and the recording layer can be formed by the same stage within the same device as to the film which is to be formed in a vacuum vessel among the recording films. Although the film thickness of the underlying layer varies with applications, 10-2,000Angstrom is generally preferable as the film thickness range at which the good C/N is obtd. and which is effective for the recording sensitivity as well. The plastic such as polycarbonate resin or acrylic resin (polymethyl methacrylate resin, etc.), and a glass can thereby be used as the substrate materials and the recording sensitivity of the optical disk is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical information recording medium capable of recording and reproducing information using a laser beam, and more specifically, the present invention relates to an optical information recording medium that can record and reproduce information using a laser beam. The present invention relates to an optical information recording medium on which a recording layer that can be recorded and reproduced by laser light is formed.

[Problems to be solved by conventional techniques and inventions] Conventionally,
A so-called write-once recording medium that records information using irreversible changes in properties or shape by laser beam irradiation uses low melting point metals such as Te and Bi and their alloy compounds as the recording layer. Alternatively, dispersions and the like have been used and have been put into practical use as recording materials for still image filing systems.

However, conventional media do not have sufficient performance in terms of recording sensitivity for applications that require high-speed recording and playback, such as computer databases, and various attempts have been made to improve this recording sensitivity. has been achieved.

As one such method, a method of improving sensitivity by providing some kind of underlayer on a substrate and providing a recording layer thereon has been reported in Japanese Patent Laid-Open Publication No. 166548/1983. However, the underlying layer reported in these studies is an organic polymer layer, and if the recording layer is formed in a vacuum chamber, there is a problem that separate processes and equipment, such as a spinner coating device, must be provided. was there. Furthermore, these organic polymer layers improve recording sensitivity when a glass substrate is used, but the present invention shows that this effect is not noticeable when using a plastic substrate such as a polycarbonate substrate or an acrylic substrate. This has been clarified by the studies conducted by, etc.

[Means for Solving the Problems] As a result of studying various underlayers that would improve recording sensitivity even on plastic substrates, the present inventors found that by using a carbon thin film as the underlayer, optical fibers with high-performance recording characteristics could be created. The inventors discovered that an information recording medium can be obtained and completed the present invention.

That is, the present invention relates to an optical information recording medium including an underlayer formed on a substrate and a recording layer formed on the underlayer, wherein the underlayer is a carbon thin film. It is related.

The substrate used in the present invention is generally disk-shaped, but may also be card-shaped or drum-shaped. Plastics such as polycarbonate resin, acrylic resin (polymethyl methacrylate resin, etc.), and glass are used as the substrate material.

The underlayer used in the present invention is a carbon thin film.

These films can be formed by a vacuum evaporation method, a sputtering method, an ion blating method, etc. Among the recording films described below, those that are formed in a vacuum chamber can be formed using the same process in the same device. It is possible to deposit two layers: a geological layer and a recording layer. The film thickness of the underlayer varies depending on the application, but the film thickness range is 10 to obtain a good C/N ratio for boat fishing and is also effective for recording sensitivity.
~2000 people is preferable, more preferably 10~500 people
It's a person.

The recording layer used in the present invention can be made of a metal-based or organic dye-based optical recording material that has good absorption rate for laser light and a low melting point, and may be either a write-once type or an erasable type. good. Specifically, write-once recording materials include Te-based alloys, such as Te-5eSTe-A.
sSTe-5b.

Te-In5Te-3n, Te-Pb, Te-B1
5Te-5e-Ti.

Te-5e-PbSTe-3e-5b%, Te-3e-
In, Te-5e-Bi, TTe-5e-Ti-A
; dispersion of Te, e.g. TeC5Te C52,
TeOx; multilayer film, e.g. 5b-Se/Bi-TeH
Examples include organic dye films, phthalocyanine dyes, cyanine dyes, and the like. Erasable recording materials include rare earth-transition metal magneto-optical materials, such as TbF.
e, TbFeCo, GdTbFe.

NdDyFeCo HTe-based alloy, e.g. Te-0-S
n-Ge, 5n-Te-3e, In-5b-Te
, Ga-Te-3e, Ge-Te: others,
Phase change alloys, such as In-5b, In-5b-Se
, 5iSn, GeSn, CuA1. Examples include AgZn. Among these, Te alloys etc.
A thin film containing Te and Se as main components is preferable, and in particular, a thin film containing Ti.

8g, Cr, Al, Sb, Pb, 8s, In
A thin film containing at least one element selected from the group consisting of , Ga, Ge, Si, and Cu is preferred.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 A carbon film with a thickness of 50 mm was formed on a φ130 mo + polycarbonate resin spiral grooved disk substrate by DC magnetron sputtering, and then Te, Se, and Ti were deposited by DC sputtering.

A 300-layer thick film was formed of a quaternary alloy made of Ag.

This disk was subjected to 24 repetitions of a signal with a frequency of 5 MHz and a duty of 40% using an 830 nm semiconductor laser.
Writing was performed at a position of φ118 mm at 0° rpm while changing the laser output, and the recording sensitivity and C/N ratio were measured.

The results are shown in Table 1.

Comparative Example 1 A disk substrate similar to that in Example 1 was coated with Te and Se having the same composition as in Example 1 without adding a carbon underlayer.

A film of only a quaternary alloy consisting of Ti and Ag was formed to a thickness of 300 mm by DC sputtering.

The recording sensitivity and C/N ratio of this disc were evaluated in the same manner as in Example 1.

The results are shown in Table 1.

Comparative Example 2 Nitrocellulose (
I? made by Daicel Chemical Industries ■? S 1/2. (hereinafter abbreviated as NC) was applied to a thickness of 100 mm using a spin code method. This disk was processed in the same manner as in Comparative Example 1, and then treated with the same Te as in Example 1 and Comparative Example 1.

A quaternary alloy film consisting of Se, Ti, and Ag was formed to a thickness of 300 mm.

The recording sensitivity and C/N ratio of the disk using NG for the underlayer were evaluated in the same manner as in Example 1.

The results are shown in Table 1.

Example 2 A spirally grooved disk substrate made of polymethyl methacrylate resin was used instead of the polycarbonate resin disk substrate of Example I, and the same film formation as in Example 1 was performed, and the same recording sensitivity and C as in Example 1 were obtained. /N ratio was evaluated.

The results are shown in Table 1.

Table 1 Note) *1: Recording laser output example 3 when the reproduction/RF output reaches 90% of its maximum value. Comparative Example 3 A film was formed in the same manner as in Example 1 except that a glass flat disk substrate was used instead of the polycarbonate resin spiral grooved disk substrate of Example 1.

Furthermore, only a quaternary alloy film made of Te, Se, Ti, and 8g as in Comparative Example 1 was formed on a glass disk substrate similar to this.

Recording was performed using these two types of disks under the same recording conditions as in Example 1, and the laser output at which pits were formed was examined.

As a result, no pits were formed in the disk without an underlayer at 10 mW or less, whereas pits were formed at 61 mW in the disk using carbon as the underlayer.

〔Effect of the invention〕

As is clear from the above results, it was confirmed that the optical disc provided with the underlayer according to the present invention has significantly improved recording sensitivity.

Applicant's agent Kaoru Furutani

Claims (1)

[Claims] 1. An optical information recording medium comprising a base layer formed on a substrate and a recording layer formed on the base layer, wherein the base layer is a carbon thin film. recoding media. 2. The optical information recording medium according to claim 1, wherein the carbon thin film has a thickness of 10 to 2000 Å. 3. The optical information recording medium according to claim 1 or 2, wherein the substrate material is polycarbonate resin, polymethyl methacrylate resin, or glass. 4. The optical information recording medium according to claim 1, wherein the recording layer is a thin film containing Te. 5. The optical information recording medium according to claim 4, wherein the thin film containing Te is made of a Te alloy. 6. The thin film containing Te has Te and Se as main components, and Ti
, Ag, Cr, Al, Sb, Pb, As, In, Ga,
5. The optical information recording medium according to claim 4, comprising at least one element selected from the group consisting of Ge, Si, and Cu.