JPH02258290A - Optical recording medium and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the amorphous stability of a recording film and its resistance to oxidation and to prolong the service life of an optical recording medium by allowing the recording film mainly composed of Te to contain N and piling the recording film between a substrate and a protective coat. CONSTITUTION:An optical recording medium 20 is composed of a substrate 11, a recording film 12 formed on the front surface of the substrate and a protective coat 13 formed on the front surface of the recording film 12. For the substrate 11, inorganic materials such as glass and organic materials such as polymethyl-methacrylate can be used. The recording film 12 is a thin layer containing at least N as a main component, and may contain elements of a low melting point other than Te. To form the recording film 12 on the front surface of the substrate 11, the substrate is sputtered in mixed N and Ar gases with Te as a target, thereby forming the film. Since sputtering is carried out with a 5 to 50% flow rate of N and Ar gases, the recording film 12 possessing high amorphous stability and enhanced resistance to oxidation is obtained on the substrate 11 with satisfactory film formation properties. A protective coat 13 is formed on the formed recording film 12.

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention records information by causing a change in optical characteristics in an irradiated portion of a recording film on a substrate by irradiating an energy beam such as light or heat. This invention relates to an optical recording medium and its manufacturing method.

Technical background of the invention Optical recording media have physical changes (pits) such as holes or four parts in a part of the recording film by irradiation with an energy beam.
There are two types of recording film, one that creates a phase change in a part of the recording film and forms an optical property change area that changes the optical properties (refractive index, reflectance, transmittance, etc.). . At present, optical recording media of a type (pit formation type) in which a physically changed part such as a hole is formed in a part of a recording film are mainstream.

However, pit-forming optical recording media: 1) requires a relatively large recording output to form pits in a part of the recording film, 2) has difficulty controlling the shape of the recording pits, and 2) has high performance. It is difficult to record the density, and it has disadvantages such as (1) it is not possible to closely peel two optical recording media and paste them together. On the other hand, optical recording media using a method (phase change method) in which a phase change is caused in a part of the recording film to form a portion with changed optical characteristics avoids the disadvantages of optical recording media using a pit formation method. can do.

As a phase change type optical recording medium, for example, T e-G
Optical recording media having a recording film made of e-3b (Japanese Unexamined Patent Application Publication No. 1981/1981), T e-S n-Z
Optical recording medium having a recording film consisting of n-8 (Japanese Patent Application Laid-open No. 6
Optical recording media having an alloy-based recording film such as No. 2-167 and FI32 are known. However, in the case of optical recording media having such alloy-based recording films, it is relatively difficult to control the alloy composition ratio when forming the alloy-based recording film on the substrate, and it is difficult to reproduce. It has the disadvantage that optical recording media having a certain level of performance cannot be manufactured with high productivity.

In addition, as an optical recording medium using the same phase change method, Tc Ox
Optical recording medium having a recording film of the JP-A-50-46-3
No. 17) is also known, but in this optical recording medium, (1) the crystallization temperature of the recording film is low, so it is amorphous, that is, it has a short life; and (2) it is not reactive under an oxygen atmosphere during its manufacture. If sputtering is performed, there is a disadvantage that since oxygen is a combustion aid, there is a possibility that safety during film formation may be compromised.

The present inventors conducted intensive studies on optical recording media having a phase change type recording film containing TO as a main component, and found that Te
By providing a recording film containing N between the substrate and the protective film, the amorphous stability of the recording film (stably maintaining the amorphous state) and oxidation resistance are improved. The present inventors have discovered that the performance of the optical recording medium can be improved, the life of the optical recording medium can be extended, and, by making the recording film within a predetermined thickness range, errors in reading information can be reduced, and the present invention has been completed.

Purpose of the Invention The present invention has been made based on such new knowledge, and aims to increase the amorphous stability of the recording film and improve the oxidation resistance, thereby extending the life of the optical recording medium. Moreover, it is an object of the present invention to provide an optical recording medium of a diurnal variation type (with less error in reading information).

Summary of the Invention In order to achieve the above object, an optical recording medium according to the present invention includes: a substrate; a recording film formed on the substrate;
A protective film is formed on the recording film, and by irradiating the recording film with an energy beam, a phase change is caused in the irradiated part of the recording film to form an optical property changing part and information is transmitted. The optical recording medium is characterized in that the recording film is a thin film containing TO and N.

Further, in the method for manufacturing an optical recording medium according to the present invention, a substrate, a recording film containing Te and N formed on this substrate, and a protective film formed on this recording film are heated, and the recording film is heated. A method for manufacturing an optical recording medium in which information is recorded by irradiating an energy beam to cause a phase change in the irradiated portion of the recording film to form an optical property changing portion, the method comprising: When forming a film on a substrate, reactive sputtering is performed using Tc as a target in an atmosphere of Ar and N2 gas, and the flow rate ratio of Ar and N2 in the Ar and N2 gases ((
It is characterized in that N2/(Ar+N2)) is 5 to 50%.

According to the optical recording medium and the manufacturing method thereof according to the present invention, a recording film containing Tc as a main component contains N and H,
By laminating this recording film between the substrate and the protective film,
The amorphous stability and oxidation resistance of the recording film are improved, and the life of the optical recording medium can be extended. Moreover, by setting the thickness of the recording film to a predetermined value, the information read error can be reduced.

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a schematic cross-sectional view of an optical recording medium according to an embodiment of the present invention.

As shown in FIG. 1, the optical recording medium 10 according to the present invention includes:
It consists of a substrate 11, a recording film 12 formed on the surface of this substrate, and a protective film 13 formed on the surface of this recording film 12.

In addition to inorganic materials such as glass or aluminum, the substrate 11 may be made of polymethyl methacrylate, polycarbonate, a polymer alloy of polycarbonate and polystyrene, an amorphous polyolefin as shown in U.S. Pat. No. 4,614,778, or poly(4-4). Methyl-
Organic materials such as 1-pentene, epoxy resin, polyethersulfone, polysulfone, polyetherimide, and ethylene/tetracyclododecene copolymer can be used. The thickness of this substrate 11 may be sufficient as long as it provides appropriate rigidity to the entire recording medium 10, and is preferably about 0.5 to 2.5 mm, particularly preferably about 1 to 1.5 mm.
It is about mm.

The recording film 12 according to the present invention is a thin film containing Tc as a main component and at least N, and may also contain low melting point elements other than To or other components.

The composition of the recording film is (TeN)1-yMy.
x
It is preferable that the range is 5 atomic %≦X≦30 atomic %. Also, M is TI Mn.

NI Zr5NbSTe, Al5PtSSs.

BI In, Se, Pb, Co, SI Pd.

At least one or more additive elements selected from Sn, Zn, Go, Sb, etc., y is 0 atomic %≦y≦60 atomic %,
Preferably, the range is 0 atomic %≦y≦40 atomic %. This is because by including N in such a range, the amorphous stability and oxidation resistance of the recording film 12 can be improved.

In the present invention, the content of each element contained in the recording film 12 is determined by ICP emission spectrometry (inductively coupled plasma emission spectrometry) for metal elements (such as Te).
Further, N is measured by ESCA (X-ray photoelectron spectroscopy).

The thickness of such a recording film 12 is 100 to 1 μm, preferably 300 to 1,500, and more preferably 700 to 1 μm.
There are about 300 people.

In order to form such a recording film 12 on the surface of the substrate 11, it can be performed, for example, as follows.

First, using To as a target, a recording film 12 made of a Te thin film containing N is formed on a substrate 11 by reactive sputtering in a mixed gas of N2 gas and Ar gas. During such reactive sputtering, N2
Flow rate ratio of gas and Ar gas (N2/ (Ar +N2)
) by i′1llJ9II, the content ratio of N contained in the recording film 12 can be i48. N
2 gas and Ar gas flow rate ratio (N2/ (Ar +N2
)l is 5-50%, preferably 10-30%. By performing sputtering at such a flow rate ratio, a recording film 12 with good amorphous stability and improved oxidation resistance is produced.
can be obtained on the substrate 11 with good film formability. Furthermore, it is also possible to form the recording film 12 on the substrate by a co-evaporation method using vapors of To and Te nitride in the form of plasma, without using the sputtering method. Further, a similar recording film 12 can also be formed by vapor phase epitaxy or plasma vapor phase epitaxy. Furthermore, as another method, Te,
Part or all of the N atoms may be ionized and deposited on the substrate in the form of a beam.

A protective film 1 is formed on the recording film 12 formed in this manner.
3 is formed. The protection M13 is desirably made of a material with low thermal conductivity (preferably 1.0 W/cIII-60 g or less) in order to prevent heat from escaping during recording to the recording film 12 and increase recording sensitivity. For example, protective film 1
3 is organic material such as ultraviolet curing resin, TI, AN, N
It is composed of an inorganic material such as ICr, or a combination of these materials. The thickness of the protective film is 50 to 1■■,
Preferably it is 100 people to 0.11-.

In order to form such a protection 113 on the surface of the recording film 12, similar to the method for forming the recording film 12 described above, reactive sputtering method, vapor phase epitaxy method, plasma vapor phase epitaxy method, vapor deposition method, etc. Alternatively, it may be applied by coating using a spin code method or the like.

To write information on the recording film 12 as described above, an energy beam such as a laser beam that is modulated (on/off) depending on the information to be recorded is irradiated onto the recording film 12 from, for example, the substrate 11 side. Therefore, the recording film 12 of the irradiation part
This is carried out by changing the phase of the composition from amorphous to crystalline, and forming an optical property changing part corresponding to the irradiated part. The reflectance R when irradiated with the reproducing laser beam is different between the optical characteristic change part and the non-optical characteristic change part (optical characteristic non-change part), and this difference in reflectance R is used to write and write information. Reading is possible.

Effects of the Invention According to the optical recording medium and the manufacturing method thereof according to the present invention, N is allowed to exist naturally in a recording film mainly composed of To,
Since this recording film is laminated between the substrate and the protective film, the amorphous stability and oxidation resistance of the recording film are improved, and the life of the optical recording medium can be extended. Moreover, by setting the thickness of the recording film to a predetermined value, the information read error can be reduced.

[Examples] The present invention will be described below based on more specific examples, but the present invention is not limited to these examples.

Example 1 In the optical recording medium 10 having the structure shown in FIG.
An amorphous polyolefin resin substrate made of ethylene/tetracyclododecene copolymer (ethylene content: 60 mol%, tetracyclododecene content: 40 mol%) was used as
The recording film 12 is made of TeN (sputtering conditions (N
2/(A r +N,,,))-20(Flow rate %))
FIG. 2 shows the change in the reflectance of the reproduction light from the substrate side with respect to the film thickness of the recording film when using the recording film.

These values are values measured with ESCA (X-ray photoelectron spectrum) model 5SX-1 (10 (manufactured by Surf Ace Science Mi L).The measurement conditions are: Background pressure: 5X10 TorrX-ray spot size : 0.6 Dragon φ Addition Integration = 6 times Excitation source: AI
K (1487 eV) α - 'ay.

Calculations were performed assuming that the wavelength of the reproduction light was λ-830 nm and that the optical recording medium was placed in the air.

In the figure, R indicates the reflectance change with respect to the film thickness of the recording layer of the optical recording medium before recording light irradiation, and Ro indicates the reflectance change after irradiation.

Under these conditions, it was confirmed that if the thickness of the recording layer was set in the range of 750 to 950 layers, the reflectance difference ΔR (-R-R') would increase and the error in reading information would decrease. .

Example 2 Sputtering conditions were set to I N 2 / (A r + N 2
) ) FIG. 3 shows the reflectance changes obtained under the same conditions as in Example 1, except that the change was changed to −40 (flow m%).

In this case, it was confirmed that if the thickness of the recording film was set in the range of 950 to 1300, the error in reading information would be reduced.

Example 3 Actually, a disk substrate made of amorphous polyolefin resin similar to that in Example 1 was used as the substrate 11, and sputtering conditions IN2/(Ar+N2))-20 (flow rate %) were applied on this disk substrate.
) reactive sputtering to form a To85N15 layer (thickness 90
0 person) as the recording film 12, and further protect M413.
An optical recording medium was created by depositing an ultraviolet curable resin into a film using a spin code method.

The C/N ratio of this optical recording medium is set at a disk rotation speed of 1.800.
rp-・Evaluation position is radius 50・Recording frequency IMHz
-When measured under the condition of -duty-50%, 40d
It was confirmed that a C/N ratio of B or higher was obtained.

Comparative Example 1 An optical recording medium was produced under the same conditions as in Example 3, except that the sputtering conditions were changed to Ar-100 flow rate %.

When the C/N ratio of this optical recording medium was measured in the same manner as in Example 3, a maximum C/N ratio of only 13 dB was obtained. This is because in the case of a recording film made of To alone, the recording film is already partially crystallized immediately after being deposited, so the change in optical properties between the laser beam irradiated area and the non-irradiated area is small. be.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an optical recording medium according to an embodiment of the present invention;
FIGS. 2 and 3 are graphs of changes in reflectance with respect to the thickness of the recording film, showing the effects of the present invention. 10... Optical recording medium 12... Recording film

Claims (1)

[Scope of Claims] 1) A substrate, a recording film formed on the substrate, and a protective film formed on the recording film, and the recording film is irradiated with an energy beam. An optical recording medium in which information is recorded by causing a change in optical characteristics in an irradiated portion of a recording film, wherein the recording film is a thin film containing Te and N. . 2) The optical recording medium according to claim 1, wherein the content of N contained in the recording film is 0.1 to 60 at % based on the total number of atoms contained in the recording film. 3) It has a substrate, a recording film containing Te and N formed on this substrate, and a protective film formed on this recording film, and this recording is performed by irradiating the recording film with an energy beam. A method for manufacturing an optical recording medium in which information is recorded by causing a change in optical properties in an irradiated part of the film, the recording film being formed on a substrate using Ar as a target. and reactive sputtering in an atmosphere of N_2 gas, and the flow rate ratio of Ar and N_2 in the Ar and N_2 gases {(N_2/(Ar+N_2)}) is 5 to 50%. 4) The above {(N_2/(Ar+N_2)} is 10 to 30
%.