JPH02266978A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To reproduce information immediately after optically recording said information without requiring any large-scale equipment by setting the reflectances of unrecorded and recorded parts to desired values through using Sb2Se3 as an optically recording film and setting the thickness of said film within a specific range. CONSTITUTION:An apparatus is equipped with a transparent base 16, an optically recording film 17 and a reflecting film 18, and antimony triselenide(Sb2Se3) is used as said optically recording film 18 and the thickness of said film is set to 55-102nm. When the reflectances of unrecorded and recorded parts for a light beam of a wavelength 780nm incoming from the base side vary as shown by the curve 11 and the thickness of said Sb2Se3 film is selected appropriately, the title optical information recording medium can obtain a satisfactory performance of more than 70% before recording and less than 28% after recording as an exclusively reproducing optical disc. Also, when a dielectric film of less than 270nm is arranged between said Sb2Se3 recording film and reflecting film 18, the Sb2Se3 recording film can absorb a recorded light beam, prevent the dissipation of a generated heat to the reflecting film which is a good heat conductor film, and recording information by a small recording light beam energy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical information recording medium on which information is recorded and reproduced using a light beam.

[Conventional technology]

Optical discs, which are one type of optical information recording medium, can be divided into read-only optical discs and recordable optical discs.

A read-only optical disk is one in which fine irregularities are formed on a transparent substrate by a method such as injection molding using a metal master disc as a mold, and a reflective film is coated on the disc.

This method requires the following steps: coating a glass disk with a photosensitizer, recording information using a laser beam, developing, electroplating, preparing a metal master disk, forming a reflective film through injection molding, and coating a protective film. Since this method requires a large amount of cost, it is suitable for mass production of a small number of products. However, this method is not suitable for small-scale production of optical discs, and in this case, one optical disc becomes expensive.

One possible method suitable for small-scale production is to use a recordable optical disc. As is conventionally known, information is recorded by irradiating an optical recording film provided on a transparent substrate with semiconductor laser light to make holes or by causing crystal phase transition, and the reflected light is used to record information. Information can be reproduced. When a recordable optical disc is used in this manner, it is possible to manufacture a read-only optical disc at low cost without the need to produce a metal master disc.

However, the reflectance of read-only optical discs made using this method is less than 50%, and cannot meet the standard for general read-only optical discs, which requires a reflectance of 709A or higher, and is not suitable for commercially available LD players. It cannot be played on a playback-only optical disc playback device such as a DVD player or a CD player.

In order to solve this problem, Japanese Patent Laid-Open Publication No. 1983-1999 was proposed as a method for inexpensively producing small-scale optical discs with the same performance as commercially available read-only optical discs, and producing optical discs that can be played on commercially available read-only optical disc players. 119755 is shown.

This is a method for recording light beam absorption on a transparent substrate.
! A method of forming a film, irradiating it with a light beam, drilling holes called bits in the recording film to record information, then adding an operation to make the recording film transparent to the light beam, and then coating it with a reflective film. Thus, a recording medium with sufficient reflectance can be obtained.

However, in order to make the optical recording film transparent after recording information and then cover it with a reflective film, it is necessary to
This has the drawback of requiring special equipment and complicating the manufacturing process. Therefore, general users who do not have such equipment have the problem of not being able to play back immediately after recording.

[Problem to be solved by the invention]

The present invention solves the above-mentioned drawbacks and provides an optical information recording medium that can reproduce information without the need for special operations using a large-scale device after recording information with a light beam, and has a high reflectance. It was done for that purpose.

[Means to solve the problem]

The optical information recording medium according to the present invention includes a transparent substrate, an optical recording film, and a reflective film, and uses antimony triselenide (s b, s 63 ) as the optical recording film, and has a film thickness of 55 mm.
It is characterized by having n- to 1021-.

[Effect]

The complex refractive index n of the 5bzSesfI film in an untreated state after film formation is 3.8-0.15 at a wavelength of 780 rv.
i, and the complex refractive index n after heat treatment at 170°C to 200°C changes to 4.7-0.7i.

Therefore, for an optical information recording medium in which a 5blSe3 recording film and a reflective film are laminated on a transparent substrate, the reflectance of the unrecorded area and the reflectance of the recorded area for a light beam of wavelength 780n@ entering from the substrate side are as shown in Figure 2. By appropriately selecting the film thickness of sb and 5e311, it has a performance that is sufficiently satisfactory as a general read-only optical disc, with a performance of 70% or more before recording and 28% or less after recording. An optical information recording medium can be obtained.

〔Example〕

FIG. 1 shows an embodiment of a recording medium according to the present invention.

In the figure, the transparent base 16 has an outer diameter of 120u.

A polycarbonate substrate with an inner diameter of 5 fl, a thickness of 1.2 mm, and a spiral tracking groove with a pitch of 1°6 μm, a width of 0.7 μm, and a depth of 0.07 μm on one side of the surface was used, and a recording film was placed on this. 5blSe3Jfl117 was 9On using a well-known sputtering method.
-, and then Au reflective film 18 was formed to a thickness of 77.5n.
The film was formed to a film thickness of -.

The reflectance of the optical recording medium produced in this way is the wavelength λ
-78% for a light beam of 780 nm. After recording information by irradiating this disk with a half-quad laser beam of wavelength λ-83 on-,
When the reflectance was measured, it was 27%, and the reflectance before and after recording met the standards for read-only optical discs.

The film thickness of the Sb2Se3 recording film at which the reflectance is 70% or more before recording and 28% or less after recording is as follows:
The diagonal line in FIG. 2 was in the range of 90n- to 102n-.

In this embodiment, the reflective film is made of Au, which has the highest reflectance at the wavelength λ-78on-. Although it is possible to obtain an optical information recording medium with a reflectance of 70% or more before recording and 28% or less after recording by using Ag*Cu or AI in addition to Au, the λ-780 of the reflective film
As the reflectance at nm decreases, 5blSe
The appropriate film thickness range for No. 3 is small.

As another embodiment of the present invention, an example will be described in which a transparent dielectric film is disposed between a 5JSel recording film and a reflective film.

In the same manner as in the previous example, S was deposited on a polycarbonate substrate.
b Zero Se3 film was formed to a film thickness of 80 ns+, and then ZnS
A dielectric film was formed to a thickness of 50 nm, and an A1 reflective film was formed to a thickness of 7 nm.
A film was formed at 0 low.

The wavelength λ-78On of the optical information recording medium thus produced
The reflectance before and after recording at - was 73% and 22%, respectively, which met the reflectance standard for read-only optical discs.

In this example, the reflectance before recording is 70% or more,
The film thickness range of the 5blSe1 recording film in which the reflectance after recording was 28% or less was 76n- to 82n-.

In addition, in this example, the reflectance was measured by replacing the A1 reflective film with an Au reflective film and varying the thickness of the SbmSe2 film, and the result was that it satisfied the reflectance standard for general read-only optical discs as described above. Therefore, the appropriate film thickness range of the 5bases recording film can be widened compared to the case where the A1 reflective film is used.

FIG. 3 shows Sb, se on the transparent substrate 16 as described above.
, 111117 and Au reflection 119I (film thickness 80rim
When a light beam with a wavelength of λ-780n is made incident from the transparent substrate side onto an optical information recording medium in which a transparent dielectric film is laminated between the In the case of a 5JSe13 recording film for making the reflectance of the information recording portion 28% or less, it is possible to obtain an optical information recording medium that satisfies the reflectance of a read-only optical disc.

In the above embodiment, Zn5 (I!!) is used as the dielectric film.
Although the refractive index n=2.3) was used, the present invention is not limited to this, and S % 0. Oxides such as S i Os and Tag Os, nitrides such as A IN and S 1 S Na, sb
Chalcogenides such as S, G, S, MgFt, CaF
It can be used as long as it is transparent at the wavelength of the reproduction light beam, such as fluorides such as *.

As in this example, sb mushroom Se, recording WA17 and reflection W4
When a dielectric film is placed between 18 and 18, the recording film absorbs the recording light beam, prevents the generated heat from diffusing to the reflective film, which is a thermally conductive film, and reduces the energy of the recording light beam. Information can be recorded in . In addition, by selecting the optical thickness of this dielectric film in the range of, for example, 70 to 100 ns, it is possible to achieve a
The thickness range of the Sl113 recording film can be widened.

〔Effect of the invention〕

In the present invention, 3blSes is used as the optical recording film, and the film thickness is 155n- to 102as, so that the reflectance of the unrecorded part can be 70% or more and the reflectance of the recorded part is 28% or less, and After information is optically recorded, it can be immediately reproduced without the need for particularly large-scale equipment.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of an optical disk according to the present invention, FIG. 2 is a diagram showing the relationship between Sb, Se, recording film thickness, and reflectance, and FIG. 3 is a cross-sectional view showing an example of an optical disk according to the present invention. FIG. 3 is a diagram showing the relationship between the optical thickness of a dielectric film and the thickness of a 5blSel recording film in an example. 16--Transparent substrate 17-3b, S., Film 18-Au reflective film g. /DQ rO sb, sa, chest thickness C? L ring)

Claims (2)

[Claims] (1) A transparent substrate, an optical recording film, and a reflective film are provided, and the optical recording film is made of antimony triselenide (Sb_2Se_3).
An optical information recording medium characterized in that the film thickness is 55 nm to 102 nm. (2) The optical information recording medium according to claim 1, wherein a transparent dielectric film is disposed between the optical recording film and the reflective film, and the optical thickness of the dielectric film is 270 nm or less.