KR100304864B1 - Method of manufacturing optical recording medium - Google Patents

Abstract

PURPOSE: A method of manufacturing an optical recording medium is provided to form a substrate, dielectric layers, a recording layer, and a reflection layer by a sputtering, and to perform an etching by a reverse sputtering for modulating power only in each forming step, so as to improve density of the dielectric layers as well as improving an attachment between the dielectric layers and the substrate. CONSTITUTION: A substrate(1) is etched by a reverse sputtering. The first dielectric layer(2) is formed to 500 angstrom units in thickness by a sputtering, and is etched by a reverse sputtering again. A recording layer(3) is formed to 1000 angstrom units in thickness by a sputtering, and is etched by a reverse sputtering. The second dielectric layer(4) is formed to 1500 angstrom units in thickness by a sputtering, and is etched by a reverse sputtering again. A reflection layer(5) is formed to 2000 angstrom units in thickness by a sputtering, and is etched by a reverse sputtering.

Description

Method of manufacturing optical recording medium

1 is a structural diagram of an optical disk.

2 is a diagram showing an embodiment of the present invention.

3 is a graph for explaining the effect of the present invention.

* Explanation of symbols for main parts of the drawings

1 substrate 2 first dielectric film

3: optical recording film 4: second dielectric film

5: reflecting film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly, to a method of manufacturing an optical recording medium for improving the density of a dielectric film as a protective film of a recording film and for improving adhesion between the dielectric film and a substrate.

Optical disks have a bright prospect as the next generation recording medium because they have high recording density due to high perpendicular magnetic anisotropy and small grain noise.

As a recording material of a conventional optical disk, a rare earth-transit-ion metal alloy film is mainly used, for example, TbFe, TeFeCo, GdFeCo, GdTbFeCo, or the like.

However, these materials have a property of shortening the life of the material and aging characteristics due to the strong affinity for the rare earth element to oxygen.

Therefore, the use of a protective film to protect against oxidation is indispensable, and the protective film is coated on the upper and lower sides of the recording film. The protective film should have excellent optical properties, chemical stability, and low reactivity with water vapor and oxidizing gas.

For example, the SiOx protective film has been widely studied, but the actual protective properties are not very good, and rather, non-oxide SiNx has been used as a promising material.

The structure of a conventional optical disk using SiNx as a protective film has a SiNx dielectric film 2, a photovoltaic film 3, and a second dielectric film, which are first dielectric films on a substrate 1, as shown in FIG. 4) The reflective film 5 is formed in a stacked four-layer structure.

In FIG. 1, reference numeral 6 denotes a magnetic head, and 7 denotes a laser.

Optical recording media approaching to practical use as high-density and large-capacity memories improve the adhesion of dielectric films and suppress the activities of impurity gases (steam, oxygen, hydrogen, etc.) generated on the substrate without complicating the structure beyond four layers. Therefore, it is required to remove the obstacles to practical use so as to secure the stability of the bit in which the signal is recorded by enhancing the protection characteristic.

The amorphous optical recording film made of rare earth transition metal has the perpendicular magnetic anisotropy that the optical recording film should have due to its affinity with water vapor (H ₂ O), oxygen (O ₂ ), hydrogen (H ₂ ), etc. of rare earth metals such as Tb, Gd, and Dy. Falls.

Sources of impurity gases such as water vapor, oxygen, and quenching, which reduce the perpendicular magnetic anisotropy, are firstly generated from walls and targets in the sputter chamber, and most of them are hydrogen. It is in the form of water vapor.

This is solved by making the sputter chamber in a high vacuum.

Secondly, it is generated from the working gas used for sputtering. In this case, it is solved by purifying Ar with an inert gas with high purity.

Thirdly, the most directly affecting the recording film is PC (Polycarbonate), which is generally used as the substrate of the optical disk. Water vapor and oxygen are formed in the pits or grooves in the pre-formed substrate. Are largely contained.

This may seriously affect the recording film during the production, even if the substrate is stored in a degas chamber or drawn out under vacuum for a long time in the vacuum sputter chamber.

Accordingly, SiNx, which is a base film having high corrosion resistance, is selected to form a SiNx thin film of about -100 mm between the substrate and the recording film.

However, since the adhesion force of the SiN _X film to the substrate is not very strong and the density is not large as an amorphous structure, there is a risk that the vapor and oxygen of the substrate are likely to penetrate the thin film.

Disclosure of Invention The present invention has been made to solve the above-mentioned problems, and to manufacture an optical recording medium that improves reliability by densifying the structure of the dielectric film, which is a protective film of the recording film of the optical recording medium, and increasing adhesion to the substrate to increase resistance to oxygen infiltration. The purpose is to provide a method.

In order to achieve the above object, in the method of manufacturing the optical recording medium of the present invention, sputtering power is sequentially formed on the substrate by sputtering the first dielectric film, the recording film, the second dielectric film, and the reflecting film. Modulating and etching each film by reverse sputtering.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

The present invention provides a method of improving the adhesion of the SiNx base film to the substrate and increasing the density of the SiNx base film itself to form a dense structure and further to remove impurities from the substrate itself, and the principle of the method is etching. The period is given to the method and the etching time.

That is, during the process, power is modulated at each step to perform reverse sputtering, that is, etching.

In other words, after mounting the substrate in the sputtering apparatus, the substrate is etched by reverse sputtering to remove the impurity gas in the substrate, and then a SiNx film is formed on the substrate as the first dielectric film by sputtering, followed by the first dielectric. By etching the film by reverse sputtering, the protective characteristic of the first dielectric film is improved.

In the process of forming the recording film, the second dielectric film and the reflective film after the formation of the first dielectric film, etching is performed by reverse sputtering as described above, respectively.

The etching by reverse sputtering is performed periodically during the formation of the respective films or after the formation of each film.

2 is a flowchart of a manufacturing process for alternately performing etching and sputtering according to an embodiment of the present invention.

Referring to the structure diagram of FIG. 1 and FIG. 2, first, the substrate 1 is etched by reverse sputtering (A), and then the first dielectric film 2 made of SiNx is formed to have a thickness of 500 kHz by sputtering. The film is etched again by reverse sputtering (B), and then the recording film 3 is formed to have a thickness of 1000 microseconds by sputtering, followed by etching by reverse sputtering (C).

Subsequently, the second dielectric film 4 is formed to have a thickness of 1500 ns by sputtering, and then it is etched by reverse sputtering (D), and then the reflective film 5 is formed to 2000 ns by sputtering, and then subjected to reverse sputtering. Etching is performed.

By simply modulating only the power in this manner, sputtering and reverse sputtering (etching) are alternately performed to form an optical recording medium having excellent characteristics.

The sensitivity of the magnetic field before and after the etching of the first dielectric film is shown in FIG. 3, which shows that the magnetic field sensitivity after etching for 5 minutes at 7 m torr and a power of 300 W is improved.

As described above, according to the present invention, by forming the substrate, the dielectric film, the recording film, the reflecting film, and the like of the optical recording medium by sputtering, etching is performed by reverse sputtering to simply modulate power at each step of forming. First, by etching the substrate, impurities in the substrate are removed to eliminate reaction between the substrate and the unnecessary impurities of the first dielectric film formed on the substrate, thereby improving adhesion between the substrate and the first dielectric film, and forming the first dielectric film. After etching, the density of the film can be improved to prevent infiltration of impurity gas, and the oxidation of the recording film formed on the first dielectric film can be prevented at the source.In addition, the magnetic field sensitivity of the recording film can be improved to improve the recording density and data. This can increase the data transfer rate.

Claims (2)

A method of manufacturing an optical recording medium for sputtering and forming a substrate, a recording film, a reflecting film, and the like, the method comprising: reverse sputtering and etching in forming the respective films. The method of manufacturing an optical recording medium according to claim 1, wherein said reverse sputtering is performed periodically during the formation of each of said films on a substrate or before forming each film.