JPH06150366A - Optical record carrier and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent the oxidation of the Te-Pd film at the substrate interface to prolong the life of the optical disk and reduce H ₂ O and N ₂ taken in at the film interface to record signals. The purpose is to improve quality. [Structure] After forming a TeOx-Pd film 12a having a thickness of 5 to 30 nm on a disk substrate 11, introduction of O ₂ is stopped and a Te-Pd film 13 is formed in a state of continuous glow discharge. Here, 0 ₂ is gradually introduced again to TeOx-Pd.
By forming the recording film by transitioning to the film, it is possible to prevent the Te-Pd film at the substrate interface from being oxidized and reduce H ₂ O and N ₂ taken in at the film interface. As a result, it is possible to realize an optical disc having a long life and high recording signal quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording which can be used for an optical disk memory for recording and reproducing an information signal by irradiating a disk rotating a high speed with a Te optical recording film with a pulse of laser light. The present invention relates to a carrier and a method for producing the carrier.

[0002]

2. Description of the Related Art A phase-change type optical disk memory using a Te-based optical recording material uses that the irradiated portion changes from an amorphous phase to a crystalline phase by heat generated when a light pulse such as laser light is irradiated. The signal is recorded by using the recording film, and the recorded signal is reproduced by the change in the reflected light amount of the recording film accompanying the change in the crystal phase.

Here, it takes a relatively short time for the tellurium oxide (TeOx film in the amorphous state where x is an upper limit of 2) to reach a crystalline state, but it takes a relatively long time. A phenomenon in which a recording signal amplitude (hereinafter referred to as an RF amplitude) of a reproduced signal after recording and a C / N value which is an amplitude ratio of a signal representing the quality of the recording signal and noise increases with time is called a sensitization phenomenon.

In order to reproduce a recorded signal with a high C / N value immediately after recording, it is necessary to eliminate the above-mentioned sensitization phenomenon and obtain a high C / N value immediately after recording. In order to improve such a sensitization phenomenon, a method of adding different kinds of materials to TeOx has been proposed.
In that method, it is considered that different kinds of materials play the role of crystal nuclei in the TeOx film, accelerate the phase change of TeOx, and improve the sensitization phenomenon.

However, when different kinds of materials are added to decrease the relative amount of Te in the recording film as described above,
It is known that the C / N value decreases. So Te
2 to 5 at% of Pd is added to the system optical recording film, and a Te-Pd metal crystal film 33 is provided between the disk substrate 31 and the TeOx-Pd recording film 32 to which Pd is added as shown in FIG. A two-layer film optical record carrier has been proposed. (For example, Japanese Patent Application No. 63-133291)

[0006]

[Problems to be Solved by the Invention]
When signals are recorded / reproduced using the Ox-Pd recording film, 33 msec after recording, which is the time required for one rotation when the optical record carrier is rotated at 1,800 rpm, and 30 sec after recording, No difference was observed in the C / N value after 60 seconds, no sensitization phenomenon was observed, and a C / N value of 57 dB was obtained when a signal having a single frequency of 5 MHz was recorded.

However, in such a conventional recording film, the interface between the disk substrate 31 and the TeOx-Pd recording film 32 is Te.
Since it is composed of the Pd metal crystal film 33, Te-
There is a problem that the Pd metal crystal film is easily oxidized in a high temperature and high humidity atmosphere.

Further, in order to form such a conventional recording film, a glow discharge is generated by using a sputtering device, and first a Te-Pd metal crystal film of the first layer is formed by sputter evaporation and then grown. The discharge is once stopped, O ₂ gas is introduced into the sputtering chamber, and then the glow discharge is restarted to form the TeOx-Pd recording film of the second layer by the reactive sputtering method. In this case, since it takes time to start forming the second layer after forming the first layer film, a small amount of H ₂ O, N ₂ etc. present in the vacuum chamber is adsorbed on the surface layer of the Te-Pd metal crystal film. However, there is a problem that it may cause a decrease in C / N depending on the film forming conditions.

For example, in order to know the disk life of the conventional disk under an atmosphere of high temperature and high humidity, an acceleration test is carried out,
32 ℃ by plotting the test results Arrhenius
Estimated life of 20 years or more was obtained by -80% RH conversion. The estimated life of 20 years is not a practical problem,
TeOx-Pd recording film When the same acceleration test is performed using a disk having a recording film of one layer, it is twice the above value.
The estimated life value in years was obtained. Therefore, in order to improve the reliability of the disk, oxidation of the film at the interface of the substrate is prevented to improve the estimated life of the disk, and at the same time, H ₂ ON ₂ adsorption to the surface layer of the Te-Pd metal crystal film is prevented to improve C / N. Must be realized.

The present invention solves the above-described problems of the conventional disk, prevents oxidation of the substrate interface portion, and
The object is to improve the reliability of the disk by improving the adsorption of H ₂ O and N ₂ on the surface layer of the Pd metal crystal film.

[0011]

In order to solve the above problems, the present invention is formed on a substrate and contains TeOx as a main component.
a TeOx-Pd recording film having a thickness of 5 to 30 nm in which d is added at 2 at% or more and less than 5 at%;
In the vicinity of the boundary with the d recording film, a Te-Pd metal crystal film is formed, and TeOx-P increases as the distance from the boundary increases.
It is configured so as to be composed of a film that gradually changes to a d-oxide film.

When an optical record carrier is manufactured, a glow discharge is generated in a vacuum chamber and at the same time O ₂ gas is introduced into the vacuum chamber to form a TeOx-Pd recording film on the substrate, and then the glow discharge is continued. Meanwhile, the O ₂ gas is stopped, the Te—Pd metal crystal film is sputter-evaporated to attach the metal crystal layer, and
₂ gas is gradually introduced and the flow rate thereof is gradually increased to transition the metal film to an oxide film, and after the transition, an optical record carrier is formed while keeping the flow rate of O ₂ gas constant. is there.

[0013]

In the optical record carrier of the present invention, after a TeOx-Pd recording film having a thickness of 5 nm to 30 nm is formed on a substrate, it is composed of a Te-Pd metal crystal film in the vicinity of the boundary, and the TeOx- The Pd oxide film is provided with a layer that gradually transitions.

In the recording film of the present invention, Pd is added in an amount of 2 at% or more and less than 5 at% at the interface with the substrate, which is 5 nm to 30 nm.
Since the TeOx-Pd recording film that is stable even under high humidity is formed, oxidation can be prevented and the weather resistance of the disk is improved. According to the test results, TeOx with Pd added
Estimated life value (32 ℃ 8
40% in terms of 0% RH) is obtained.

When forming a conventional disk, the first method is used.
It takes time to start forming the second layer after forming the layer film, but according to the present invention, after forming the TeOx-Pd recording film on the substrate, the O ₂ gas is stopped while continuing the glow discharge, and Te- P
d. While the metal crystal film is being formed, O ₂ gas is gradually introduced again, and the flow rate thereof is gradually increased to transition to the oxide film. After the transition, a constant flow rate of O ₂ gas is flowed, so that continuous growth is achieved. - H ₂ O to the discharge persists Te-Pd metal crystal film surface layer, it is possible to prevent the N ₂ adsorption, the C / N ratio can be increased further 2dB compared with the conventional example by a result the present invention, 59 dB The degree can be stably obtained.

[0016]

FIG. 1 shows the structure of an optical record carrier manufactured by a manufacturing method according to an embodiment of the present invention. As shown in the figure, the surface of the disk substrate 11 is made of TeOx- with a thickness of 5 to 30 nm.
Pd recording film 12a, Te-Pd metal crystal film 13, T
e-Pd oxide transition layer 14, TeOx-Pd
The recording film 12b is formed.

The optical record carrier of the present invention can be formed by, for example, a sputter evaporation method as shown in FIG. As shown in FIG. 2, the inside of the vacuum chamber 21 is, for example, 10 ⁻⁶ T
Evacuate to orr level. After evacuation, A in the vacuum chamber
For example, 50 sccm of r gas is continuously introduced and O ₂ gas is added to 1
Introduce 0 SCCM and adjust the pressure in the vacuum chamber to 5 × 10 ⁻³ Torr. At this time, the disk substrate 11 is rotationally driven by the motor 22 in order to suppress the film thickness distribution during film formation. Target 23 containing Te and Pd in this state
Apply DC or AC power to. For example, DC10
When an electric power of 0 W is applied, glow discharge occurs in the vacuum chamber, Te-Pd is combined with O ₂ molecules existing in the vacuum chamber, and a TeOx-Pd film 12a is formed on the disk substrate 11. In this example, the TeOx-Pd recording film 12a having a thickness of 10 nm could be formed in about 30 seconds.

Here, if the thickness of the TeOx-Pd recording film 12a is less than 5 nm, the film cannot be completely formed on the entire surface and the film having an island structure is formed and is not uniformly distributed on the substrate, so that the effect of preventing oxidation is obtained. It is low and Te-Pd when the film thickness exceeds 30 nm.
A film stress is generated between the film and the metal crystal film 13, and peeling easily occurs at the film boundary. As a result, water molecules and the like enter the peeled portion, the film is oxidized, and normal recording and reproduction cannot be performed.
Therefore, the thickness of the TeOx-Pd film 12a is 5 to 30 n.
It is desirable to be within the range of m.

At the same time as the formation of the TeOx-Pd film 12a is completed and the introduction of O ₂ gas is stopped while continuing the glow discharge, the Te-Pd metal crystal film 13 adheres to the disk substrate. After that, when the introduction valve of O ₂ gas is gradually opened again to increase the amount thereof, the reactive sputtering proceeds in the vacuum chamber 21 to form the layer 14 which is transformed into the oxide of the Te—Pd film. Gradually increase the flow rate of O ₂ gas to 10 SCCM
When the flow rate of O ₂ gas is kept constant in that state, the TeOx-Pd recording film 12b is attached. According to this example, a film having a thickness of about 100 nm could be formed with a sputtering time of about 3 minutes.

Here, Te-Pd metal crystal film 13, TeO
If the Pd content of the x-Pd recording film 12b is 2 at% or less, the sensitization phenomenon is confirmed. For example, if Pd is added at 1.5 at%, the C / N value is about 33 to 60 seconds after recording. It increases by 1 dB. Also, when the content is 5 at% or more, TeOx
Will decrease the C / N value. Therefore, it is desirable that the added amount of Pd be 2 at% or more and less than 5 at%.

The target 23 used in this embodiment is as follows.
May contain Te and Pd, and T
Using the target of e and the target of Pd, these 2
Similar effects can be obtained by simultaneously sputtering and evaporating different types of targets.

The optical record carrier prepared according to the present embodiment described above is rotated at, for example, 1,800 rpm to obtain a single frequency,
For example, the C / N value was measured 33 seconds after recording a signal of 5 MHz and after 60 seconds. In each case, a good C / N value of 59 dB was obtained. Also, 3
The life expectancy value of 40 years, which is twice the conventional value, was obtained at 2 ° C and 80% RH conversion.

[0023]

As is apparent from the above description of the embodiments, the optical record carrier of the present invention has a Te thickness of 5 to 30 nm.
After forming the Ox-Pd recording film on the substrate, Te is formed near the boundary.
A layer made of a -Pd metal crystal film is provided, which gradually transitions to a TeOx-Pd oxide film as it moves away from the vicinity of the boundary. Since a stable TeOx-Pd recording film is provided on the substrate, the film is less likely to be oxidized even under high temperature and high humidity, weather resistance can be improved, and the estimated life of the disk can be twice as long as that of the conventional one. can get.

Further, after the TeOx-Pd recording film is formed on the substrate, the O ₂ gas is stopped while continuing the glow discharge and Te-Pd.
While the metal crystal film is being formed, O ₂ gas is gradually introduced again, and the flow rate thereof is gradually increased to transition to the oxide film. After the transition, a constant flow rate of O ₂ gas is flowed, so that continuous growth is achieved. Discharge is sustained and H ₂ O and N ₂ adsorption to the Te-Pd metal crystal film surface layer can be prevented, resulting in a good C / N ratio.
The effect that the ratio can be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing the configuration of an optical record carrier according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing the same manufacturing process.

FIG. 3 is a sectional view of a conventional optical record carrier.

[Explanation of symbols]

 11 Disk Substrate 12a TeOx-Pd Recording Film 12b TeOx-Pd Recording Film 13 Te-Pd Metal Crystal Film 14 Layer Transition to Oxide of Te-Pd 21 Vacuum Chamber 22 Motor 23 Target

Claims (2)

[Claims] 1. A main component of tellurium oxide (TeOx, where x is an upper limit of 2) formed on a substrate, and palladium (P
5 to 30 nm when d) is added at 2 at% or more and less than 5 at%
Tellurium oxide-palladium (TeOx-P
d) A recording film and a tellurium palladium (Te-Pd) metal crystal film in the vicinity of the boundary on the TeOx-Pd recording film.
d An optical record carrier having a Te-based phase change recording film that gradually transitions to a recording film. 2. When producing an optical record carrier comprising a Te-based phase change recording film formed on a substrate, glow discharge is generated in a vacuum chamber, and at the same time, oxygen (O ₂ ) gas is supplied to the vacuum chamber. After introducing and forming a TeOx-Pd recording film on the substrate, O ₂ gas is stopped while continuing the glow discharge, the Te-Pd metal is sputter-evaporated, and a Te-Pd metal crystal film is attached again to O ₂ gas. gradually introduced, allowed transition to the oxide film of the metal film by increasing the flow rate gradually after transition O ₂
A method of manufacturing an optical record carrier, which comprises forming a Te-based phase change recording film while keeping a gas flow rate constant.