JPH11345438A - Optical recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain always stable and good recording and reproducing characteristics in spite of repetitive recording by executing sputtering in a gaseous Ar atmosphere contg. at least either of gaseous N2 and gaseous O2 , thereby depositing a recording film contg. a GeSbTe alloy. SOLUTION: At the time of depositing the recording film by using the GeSbTe alloy as a phase transition material, the film is deposited by sputtering in the gaseous Ar atmosphere contg. at least either of the gaseous N2 and gaseous O2 . At the time of depositing the recording film in this process for producing the optical recording medium, the deposition is preferably executed with conditions under which equation I, equation II and equation III are satisfied in the gaseous Ar atmosphere contg. the gaseous N2 and gaseous O2 when the mixing ratio (N2 +O2 )/Ar of the gaseous N2 and gaseous O2 to the gaseous Ar is defined as Y[%], the ratio O2 /(N2 +O2 ) of the gaseous O2 occupying in the gaseous N2 and gaseous O2 as Z[%] and the deposition rate as X [nm/s].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to providing a recording film made of a phase change material which causes a phase change between a crystalline state and an amorphous state, and irradiating a light beam to cause a phase change in the recording film. And a method for manufacturing the same.

[0002]

2. Description of the Related Art Optical recording media for recording and / or reproducing various information signals by irradiating a light beam such as a laser beam include:
For example, an optical disk in which an information signal is written in advance by emboss pits, a phase change optical disk in which an information signal is written by using a phase change between a crystalline state and an amorphous state of a recording layer, and a magneto-optical effect of a recording layer And a magneto-optical disk on which an information signal is written by utilizing the above.
Each of these optical discs has a configuration in which a recording layer and a functional film such as a light reflection film are provided on a transparent substrate made of plastic such as polycarbonate or glass.

Among the above-mentioned optical recording media, magneto-optical disks and phase-change optical disks are rewritable. In particular, phase-change optical disks have attracted attention because they can be easily rewritten and can be recorded and reproduced without using a means for generating an external magnetic field, so that the recording and reproducing apparatus can be downsized. I have.

When an information signal is recorded on such a phase-change optical disk, the recording layer is irradiated with a laser beam having a high level of power (hereinafter referred to as recording power), so that the recording layer has a temperature higher than its melting point. The temperature is raised. After that, the portion of the recording layer irradiated with the laser light becomes an amorphous recording mark in an amorphous state by being rapidly cooled.

When erasing the information signal recorded on the recording layer of the phase change optical disk, a laser beam having a lower power than the laser beam irradiated at the time of recording is irradiated onto at least the recording mark, and The irradiated portion is heated to a temperature higher than the crystallization temperature and lower than the melting point temperature, and then cooled, whereby the already-recorded amorphous recording mark portion becomes crystalline and is erased.

Further, in this phase-change optical disk, since the reflectivity differs depending on whether the material constituting the irradiated portion of the recording layer is in a crystalline state or an amorphous state, the weakest laser beam is applied to the recording layer. Thus, the information signal is reproduced by detecting a change in the reflectance in each of these states.

[0007] Such a phase-change optical disk uses, for example, a Ge-Sb-Te-based Ge or the like as a constituent material of a recording layer.
(Hereinafter, referred to as a Ge-based chalcogen compound) and Ag-In-Sb-Te-based A
and a phase change material such as a chalcogen compound containing g (hereinafter, referred to as an Ag-based chalcogen compound). Above all, it is known that a phase-change optical disk using a Ge-based chalcogen compound as a constituent material of a recording layer is superior in repeated recording durability to a phase-change optical disk using an Ag-based chalcogen compound as a constituent material of a recording layer. ing.

[0008]

However, a phase-change optical disk using a Ge-based chalcogen compound as a constituent material of a recording layer has a longer recording durability than a phase-change optical disk using an Ag-based chalcogen compound as a constituent material of a recording layer. However, the signal characteristics of the reproduced signal deteriorate locally when the recording is repeated several to several tens of times, or the signal characteristics of the reproduced signal are reduced when the recording is repeated several tens of thousands of times. There is a problem that it deteriorates rapidly.

Therefore, in this phase change optical disk, a stable reproduction signal cannot be obtained when the number of repetitive recordings is a small number such as several to several tens. Further, in this phase-change optical disc, when the number of times of repetitive recording is tens of thousands or more, a good reproduction signal cannot be obtained, and as a result, signal characteristics lack reliability. .

Accordingly, the present invention has been proposed in view of the above-mentioned conventional circumstances, and further improved durability of repetitive recording has been achieved. An object of the present invention is to provide an optical recording medium capable of obtaining recording / reproducing characteristics and a method for manufacturing the same.

[0011]

The optical recording medium of the present invention comprises:
An optical recording medium in which an information signal is recorded by providing a recording film made of a phase change material in which a phase change between a crystalline state and an amorphous state occurs, and irradiating a light beam to cause a phase change in the recording film. The phase change material contains a GeSbTe alloy, and the recording film is formed by sputtering under an Ar gas atmosphere containing at least one of N ₂ gas and O ₂ gas. I do.

In the optical recording medium according to the present invention as described above, since the conditions for forming the recording film are defined, the GeSbTe alloy constituting the recording film is suitably nitrided and oxidized, and the physical properties of the recording film are recorded. The reproduction characteristics are optimized, and the repetitive recording durability is further improved. Thereby, in the optical recording medium according to the present invention, the local deterioration phenomenon of the reproduction signal seen after performing the recording several to several tens of times is suppressed as much as possible, and even if the recording is repeated several tens of thousands or more times, it is satisfactory. As a result, stable and good recording / reproducing characteristics are always obtained even after repeated recording.

Specifically, in the optical recording medium of the present invention, when the recording film is formed in an Ar gas atmosphere containing N ₂ gas and O ₂ gas, the N ₂ gas with respect to the Ar gas
The mixing ratio of gas and O ₂ gas (N ₂ + O ₂ ) / Ar is Y
And [%], the ratio O ₂ / a O ₂ gas occupying the said N ₂ gas and O ₂ gas (N ₂ + O ₂₎ and Z [%], when the film formation rate was X [nm / s], X, Y and Z preferably satisfy the following formulas (15), (16) and (17).

Y ≧ 2.3X + 1.0 (15) Y ≦ 12.8X + 16.7 (16) 10 ≦ Z ≦ 60 (17) In the optical recording medium of the present invention, said recording film, if formed by deposition under Ar gas atmosphere containing O ₂ gas, the mixing ratio O ₂ / Ar between the O ₂ gas and the Ar gas was Y [%], the film formation rate Is X [nm / s],
X and Y preferably satisfy the following formulas (18) and (19).

Y ≧ 2.3X + 1.0 (18) Y ≦ 5.5X + 2.7 (19) In the optical recording medium of the present invention, the recording film contains N ₂ gas. When a film is formed in an Ar gas atmosphere, the mixing ratio N ₂ / Ar of N ₂ gas and Ar gas is set to Y [%].
When the film formation rate is X [nm / s], X and Y
Preferably satisfies the following formulas (20) and (21).

Y ≧ 1.8X + 5.0 (20) Y ≦ 12.8X + 16.7 (21) Further, the method of manufacturing an optical recording medium according to the present invention is characterized in that a crystalline state and an amorphous state A method for manufacturing an optical recording medium, comprising: a recording film made of a phase-change material in which a phase change occurs between the recording films, wherein an information signal is recorded by irradiating a light beam to cause a phase change in the recording film. When the recording film is formed using a GeSbTe alloy as a variable material, the film is formed by sputtering in an Ar gas atmosphere containing at least one of N ₂ gas and O ₂ gas.

In the method of manufacturing an optical recording medium according to the present invention as described above, since the conditions for forming the recording film are defined, the GeSbTe alloy forming the recording film is suitably nitrided and oxidized to form the recording film. The physical properties are optimized with respect to the recording / reproducing characteristics, and the repetitive recording durability is further improved. Thereby, according to the method for manufacturing an optical recording medium according to the present invention,
The local degradation phenomenon of the reproduction signal seen after performing the recording several to several times repeatedly is suppressed as much as possible, and a good reproduction signal is obtained even if the recording is repeated several tens of thousands or more times. As a result, An optical recording medium always having stable and good recording / reproducing characteristics even after repeated recording can be obtained.

Specifically, in the method of manufacturing an optical recording medium according to the present invention, when forming the recording film, an N ₂ gas and an N ₂ gas are mixed in an Ar gas atmosphere containing an N ₂ gas and an O ₂ gas. The mixing ratio of the _two gases and the O ₂ gas (N ₂ + O ₂ ) / Ar is Y
And [%], the ratio O ₂ / a O ₂ gas occupying the said N ₂ gas and O ₂ gas (N ₂ + O ₂₎ and Z [%], when the film formation rate was X [nm / s], The following equation (22) and equation (2)
It is preferable to form a film under the conditions satisfying 3) and Expression (24).

Y ≧ 2.3X + 1.0 (22) Y ≦ 12.8X + 16.7 (23) 10 ≦ Z ≦ 60 (24) Production of the optical recording medium of the present invention in the method, in forming the recording film, under an Ar gas atmosphere containing O ₂ gas, the mixing ratio O ₂ / Ar between the O ₂ gas and Ar gas Y
[%] And the film formation rate is X [nm / s], it is preferable to form a film under the conditions satisfying the following formulas (25) and (26).

Y ≧ 2.3X + 1.0 (25) Y ≦ 5.5X + 2.7 (26) In the method of manufacturing an optical recording medium according to the present invention, when forming the recording film, a, under an Ar gas atmosphere containing N ₂ gas, the mixing ratio N ₂ / Ar between the N ₂ gas and Ar gas Y
[%] And the film formation rate is X [nm / s], it is preferable to form a film under the conditions satisfying the following formulas (27) and (28).

Y ≧ 1.8X + 5.0 (27) Y ≦ 12.8X + 16.7 (28)

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a phase change optical disk 1 to which the present invention is applied.
FIG. 2 is an enlarged cross-sectional view showing a main part of FIG.

The phase change optical disk 1 to which the present invention is applied
As shown in FIG. 1, a first dielectric film 3, a recording film 4, a second dielectric film 5, a light reflection film 6, and a protective film 7 are laminated on a substrate 2 in this order.

The substrate 2 has a groove 2b formed on one main surface 2a along a recording track. The thickness of the substrate 2 is, for example, 0.6 mm. Examples of the substrate 2 include a plastic substrate made of an acrylic resin such as polycarbonate (PC) and polymethyl methacrylate (PMMA), and a glass substrate. The substrate 2 is formed, for example, by an injection molding method or a photopolymer method (2
P method) or the like. When information signals are recorded / reproduced, a light beam such as a laser beam enters from the substrate 2 side.

The recording film 4 is formed on the first dielectric film 3. The recording film 4 is made of a phase change material that reversibly changes phase between a crystalline state and an amorphous state by irradiation with a light beam such as a laser beam. This is an optical recording layer on which signal writing, erasing, and reproduction can be performed.

More specifically, the phase change material constituting the recording film 4 is heated to a temperature higher than the melting point and then rapidly cooled to be in an amorphous state. On the other hand, this phase change material is brought into a crystalline state by being cooled to a temperature below the melting point and above the crystallization temperature and then cooled. Therefore, when an information signal is recorded, the recording film 4 is rapidly cooled after being heated to a temperature equal to or higher than the melting point of the phase change material, thereby forming an amorphous recording mark.

The recording film 4 has a different reflectance depending on whether it is in a crystalline state or an amorphous state. Therefore, the information signal is reproduced by irradiating the recording film 4 with the laser light and detecting a change in the reflectance of the return light of the laser light.

In particular, the phase change material of the recording film 4 in the present invention is a chalcogen compound made of a Ge—Sb—Te alloy. The recording film 4 has a thickness of 18 nm to 3 nm.
Preferably, it is 0 nm.

Here, the recording film 4 is made of N ₂ gas and O ₂
In an Ar gas atmosphere containing a gas, the mixture ratio of N ₂ gas and O ₂ gas to Ar gas (N ₂ + O ₂ ) / Ar is set to Y.
And [%], when the O ₂ proportion of gas O ₂ / (N ₂ + O ₂₎ occupying this N ₂ gas and O ₂ gas and Z [%], the deposition rate was X [nm / s], The following equation (29) and equation (3)
It is preferable that the film be formed by sputtering under the conditions satisfying (0) and the expression (31).

Y ≧ 2.3X + 1.0 (29) Y ≦ 12.8X + 16.7 (30) 10 ≦ Z ≦ 60 (31) The mixture ratio (N ₂ + O ₂₎ ) / Ar is (N ₂ + O ₂ )
And Ar flow rate ratio, in other words, (N
₂ + O ₂ ) and the volume ratio of Ar. The ratio O ₂ / (N ₂ + O ₂ ) is a flow ratio of O ₂ and (N ₂ + O ₂ ), in other words, O ₂ and (N ₂ +
O ₂ ).

Further, when the film forming speed X is 0.1 nm / s
As mentioned above, it is preferable that it is 5.0 nm / s or less. That is, it is preferable that X satisfies the following expression (32).

[0032] 0.1 ≦ X ≦ 5 ··· (32 ) 1. Inspection of the atmospheric conditions and the deposition rate X during the deposition of the recording film
As described above 討, in the optical recording medium and a manufacturing method thereof embodying the present invention, when forming the recording layer 4, the mixing ratio of N ₂ gas and O ₂ gas to the Ar gas Y [%] and formed The film speed X [nm / s] is calculated by the above formulas (29) and (30).
The reasons specified as (31) and (31) are based on the following experimental results. Hereinafter, this experiment will be described in detail.

1-1 Atmosphere Conditions During Recording Film Formation
Relationship between the signal characteristics of the reproduced signal is first to prepare a phase-change optical disk as follows.

First, the diameter is 120 mm and the thickness is 0.6 m
m substrate 2 was prepared. Then, a film having a thickness of 1
The first dielectric film 3 made of ZnS-SiO ₂ of 20nm
Was formed by sputtering.

Next, Ge _{2 is} deposited on the first dielectric film 3.
Using a target made of Sb ₂ Te ₅ , the film deposition rate was set to 0.42 nm / s, and a film thickness of 25 was formed by sputtering in an Ar gas atmosphere in which N ₂ gas and O ₂ gas were mixed.
A recording film 4 made of Ge-Sb-Te having a thickness of nm was formed by sputtering.

[0036] O In this case, as an Ar gas atmosphere of a mixture of N ₂ gas and O ₂ gas, occupying the N ₂ gas and O ₂ gas
Is fixed to ₂ ratio of gas O ₂ / (N ₂ + O ₂₎ of 20%, the mixing ratio of the N ₂ gas and O ₂ gas to the Ar gas (N ₂ + O ₂₎ / Ar 0% to 20% Range,
A plurality of recording films were formed under each condition.

However, when the above mixing ratio (N ₂ + O ₂ ) / Ar is 0
% Is defined as Ar, which does not contain N ₂ gas and O ₂ gas.
It shows a gas atmosphere, not a recording film forming condition in the manufacturing method to which the present invention is applied.

Next, on the recording film 4 formed under each condition, a second dielectric film 5 made of ZnS-SiO ₂ with a thickness of 15 nm, and a light reflection film 6 made of an Al alloy with a thickness of 150 nm Were sequentially formed by sputtering, and a UV-curable resin was applied on the light reflecting film 6 to form a protective film 7, whereby the phase-change optical disc 1 was manufactured.

Then, two phase change optical disks 1 manufactured in this manner are manufactured two by two, and the two phase change optical disks are bonded with an adhesive 9 so that the light reflection films 6 face inward each other. The diameter is 1.2 mm and the thickness is 1.2 mm that can be recorded and reproduced from both sides as shown in FIG.
mm double-sided phase change optical disc 10 was produced. In addition,
The phase change optical disk 10 has a track pitch of about 0.5.
8 μm, and has a recording capacity of about 3.0 GB per side.

As described above, a plurality of phase-change optical discs manufactured by changing the film forming conditions were subjected to an initialization process for irradiating a strong laser beam to crystallize the recording film 4.

Then, on these phase-change optical disks after initialization, a random EFM signal was recorded with a Channel Clock of 27.7 MHz using a light emission pattern as shown in FIG. Here, in FIG. 3, the recording power is indicated by Ph, the erasing power is indicated by Pl, and the cooling power is indicated by Pc. Also, the light emission pattern in FIG.
T, and the pulse length of one light emission pulse was 13 ns.

At this time, the linear velocity is 4.8 m / s,
The recording power Ph is 14.5 mW, and the erasing power Pl
Was 5.8 mW, and a recording / reproducing apparatus having a cooling power Pc of 1.5 mW was used. The recording / reproducing apparatus is equipped with a light source for generating a laser beam having a wavelength of 650 nm.

Under such conditions, recording was repeated twice on each phase change optical disk.

Then, in order to evaluate the relationship between the condition of the mixed gas of N ₂ gas and O ₂ gas at the time of forming the recording film and the signal characteristics of the reproduced signal, each phase change optical disk after the recording was repeated twice. Then, the jitter value of the reproduced signal after repeated recording was measured.

FIG. 4 shows the results. FIG. 4 shows that the horizontal axis represents A
Mixing ratio of N ₂ gas and O ₂ gas to r gas (N ₂ +
O ₂ ) / Ar was taken, and the vertical axis represents the jitter value of the reproduced signal when recording was repeatedly performed on the same track twice.

Here, the jitter value at which a good reproduced signal is obtained after a small number of repetitive recordings, such as two, is 1
0% is defined as a media evaluation reference value.

In the above experiment, the jitter value after the recording was repeated twice was measured, for the following reason. That is, usually, the jitter value after repeated recording is highest after recording twice, and tends to gradually decrease until it reaches 10,000 times of repeated recording.
Therefore, here, the jitter value of the reproduced signal after the recording was repeated twice was measured.

As is apparent from the results shown in FIG. 4, the jitter value is obtained when the mixing ratio (N ₂ + O ₂ ) / Ar is 0%, that is, the N ₂ gas and the O ₂ gas are mixed in the Ar gas. In the case where there is no gas, the highest value is 12.7%, which decreases as the proportion of N ₂ gas and O ₂ gas increases, and the mixture ratio (N ₂ +
The minimum value is obtained when O ₂ ) / Ar is 6% to 10%. When the mixing ratio (N ₂ + O ₂ ) / Ar further increases, the jitter value gradually increases.

Therefore, as shown in FIG. 4, in order to set the jitter value of the reproduced signal after repeated recording to 10% or less, which is a level at which a good reproduced signal can be obtained, the mixing ratio (N ₂
+ O ₂ ) / Ar was found to be desirable to form the recording film in an Ar gas atmosphere of 6% or more.

1-2. Atmospheric conditions and various data when forming the recording film
The relationship between the groove reflectance of the disc then the atmospheric conditions at the time of recording film deposition, in order to evaluate the relationship between the reflectance in the groove of each disc, when similarly recording film deposition and experiment of FIG. 4 described above The reflectivity in the groove was measured for each phase-change optical disc after being prepared and initialized by changing the atmosphere conditions of the above.

FIG. 5 shows the result. In FIG. 5, the horizontal axis represents the mixture ratio of N ₂ gas and O ₂ gas to Ar gas (N ₂ +
O ₂ ) / Ar was taken, and the vertical axis was the reflectance in the groove.

As apparent from the results shown in FIG. 5, the reflectivity in the groove monotonously decreases as the mixing ratio (N ₂ + O ₂ ) / Ar increases. Then, the mixture ratio (N ₂ +
When O ₂ ) / Ar is 21.0% or more, the reflectivity in the groove becomes 11% or less, which causes a problem that a sufficient degree of modulation cannot be obtained.

Therefore, in order to ensure a sufficient degree of modulation, the mixture ratio (N ₂ +
O ₂ ) / Ar was found to be 21.0% or less.

1-3 Both Signal Characteristics and Groove Reflectance
As described above, from the results of FIGS. 4 and 5, in the optical recording medium to which the present invention is applied and the method of manufacturing the same, the recording film deposition rate is set to 0.42 nm / s. , the ratio O ₂ / a O ₂ gas occupying the N ₂ gas and O ₂ gas (N ₂ + O ₂₎ upon 20%, in order to satisfy both conditions of the jitter and reflectance in the groove of the reproduction signal Has found that it is necessary to form a recording film in an Ar gas atmosphere having a mixture ratio (N ₂ + O ₂ ) / Ar of 6% to 21.0%.

The results shown in FIGS. 4 and 5 are for an optical disk on which a recording film is formed at a film forming speed of 0.42 nm / s. Therefore, in order to obtain the same characteristics as those of the optical disks of FIGS. 4 and 5 when the film forming speed is changed, the mixture ratio of N ₂ gas and O ₂ gas to Ar gas (N
₂ + O ₂ ) / Ar also needs to be changed.

1-4 Atmosphere in the case of changing the film forming rate
And囲気conditions, the relationship between the signal characteristic and groove reflectivity Accordingly, next, the case of changing the deposition rate of the recording film, the mixing ratio to satisfy both conditions of jitter and groove reflectivity of the reproduction signal (N ₂ + O ₂ ) / Ar was studied.

First, the applied voltage of the target made of Ge ₂ Sb ₂ Te ₅ was changed, and the deposition rate of the recording film was set to 0.1 n.
m / s, and the mixture ratio of N ₂ gas and O ₂ gas to Ar gas (N ₂ + O ₂ ) /
Except that the recording film was formed under the condition where Ar was changed from 0% to 20%, in the same manner as the experiment of FIG.
An optical disk was manufactured. Then, as in the experiment of FIG. 4, the jitter value of the reproduced signal after repeated recording on the optical disk was measured. FIG. 6 shows the result. At this time, O ₂ occupying the N ₂ gas and O ₂ gas
The gas ratio O ₂ / (N ₂ + O ₂ ) is fixed at 20%.

Further, the film forming speed of the recording film is set to 0.1 nm / s.
The reflectivity of the groove after the initialization of the optical disk manufactured by changing the atmosphere conditions at the time of forming the recording film as described above was measured in the same manner as in the experiment of FIG. FIG. 7 shows the result.

Similarly, the film forming speed of the recording film is set to 1.6 n.
m / s, and a mixture ratio of N ₂ gas and O ₂ gas to Ar gas (N ₂ + O ₂ ) / Ar
An optical disk was prepared as described above, except that the recording film was formed under the condition that was changed from 0% to 45%.
The jitter value of the reproduced signal after the recording was repeated twice and the reflectivity of the groove after the initialization were measured on the optical disc in the same manner as in the experiments of FIGS. The results are shown in FIGS. 8 and 9, respectively.

Similarly, the film forming speed of the recording film was set to 5.0 nm / s, and
Mixing ratio of N ₂ gas and O ₂ gas to r gas (N ₂ +
An optical disk was manufactured as described above, except that the recording film was formed under the condition that O ₂ ) / Ar was changed from 0% to 90%. In the same manner as in the experiment, the jitter value of the reproduced signal after the recording was repeated twice and the reflectivity of the groove after the initialization were measured. The results are shown in FIGS. 10 and 11, respectively.

From the results shown in FIGS. 6, 8 and 10, the film formation rates were set to 0.1 nm / s, 1.6 nm / s, and 5.0, respectively.
In the case of an optical disk on which a recording film is formed at nm / s, the mixture ratio (N ₂ +
O ₂ ) / Ar was found to be 5%, 8%, and 14% or more, respectively.

From the results of FIG. 7, FIG. 9 and FIG. 11, the film formation rates were set to 0.1 nm / s, 1.6 nm / s, and 5.0, respectively.
On an optical disk on which a recording film is formed at a rate of nm / s, the mixture ratio (N ₂ + O ₂ ) / A at which the groove reflectivity is 11% or more is obtained.
r was found to be 17%, 40%, and 80% or less, respectively.

1-5 Both Signal Characteristics and Groove Reflectance
As discussed above recording film deposition conditions satisfying the square condition, FIG. 4, FIG. 6, the results of FIG. 8 and FIG. 10, the deposition rate 0.42 nm / s, 0.1 nm / s,
In an optical disc on which a recording film is formed at 1.6 nm / s and 5.0 nm / s, the jitter value of the reproduced signal is 10
% (N ₂ + O ₂ ) / Ar is 6
%, 5%, 8%, and 14%. The horizontal axis represents the deposition rate, and the vertical axis represents the mixing ratio (N ₂ + O ₂ ).
As shown in FIG. 12 by taking / Ar, a straight line α was obtained.

In FIG. 12, the film formation rate on the horizontal axis is X [nm /
s], and the mixing ratio (N ₂ + O ₂ ) / Ar on the vertical axis is Y [%].
And Then, the straight line α is represented by Y = 2.3X + 1.0. Here, the area below the straight line α is an area where the jitter value of the reproduction signal becomes 10% or more and a good reproduction signal cannot be obtained.

On the other hand, as described above, FIGS.
From the results shown in FIG. 11 and FIG.
In an optical disk on which a recording film is formed at 0.1 nm / s, 1.6 nm / s, and 5.0 nm / s, the mixture ratio (N ₂ + O ₂ ) / is such that the reflectivity in the groove is 11% or more.
Ar was 21%, 17%, 40%, and 80%, respectively. The results are shown in FIG. 12, with the horizontal axis representing the film forming rate and the vertical axis representing the mixing ratio (N ₂ + O ₂ ) / Ar.
It became a straight line β.

Then, the straight line β is expressed as Y = 12.8X + 1
6.7. Here, the region above the straight line β is a region where the groove reflectance is 11% or less and a sufficient signal modulation degree cannot be obtained.

If the film forming speed X is larger than 5.0 nm / s, the film forming speed is too high and the film forming time is too short, so that it is difficult to adjust the film thickness, and the film forming speed X is smaller than 0.1 nm / s. This is unsuitable for production because it takes too much time for film formation. Therefore, it is preferable that the film forming speed X satisfies 0.1 ≦ X ≦ 5.0.

As can be seen from the above results, the phase-change optical disc 1 to which the present invention is applied is formed under the Ar gas atmosphere containing the N ₂ gas and the O ₂ gas when forming the recording film made of the GeSbTe alloy. Te, the mixing ratio of N ₂ gas and O ₂ gas to the Ar gas (N ₂ + O ₂₎ / Ar was used as a Y [%], the ratio of O ₂ gas occupying the N ₂ gas and O ₂ gas O ₂ /
(N ₂ + O ₂ ) is set to Z [%], and the film formation rate is set to X [nm /
s], the film is preferably formed by sputtering under the conditions satisfying the following formulas (33) and (34).

Y ≧ 2.3X + 1.0 (33) Y ≦ 12.8X + 16.7 (34) At this time, in the phase-change optical disc 1 to which the present invention is applied, recording is performed as described above. When the film forming speed X of the film 4 is 0.1
It is preferable that ≦ X ≦ 5.0.

2. O ₂ / (N ₂ + O at the time of recording film formation
Proper value of ₂₎ Next, the ratio of O ₂ gas occupying the N ₂ gas and O ₂ gas O ₂
Consider the optimal value for / (N ₂ + O ₂ ).

Atmosphere conditions at the time of forming the recording film are as follows.
The proportion of O ₂ gas occupying the N ₂ gas and O ₂ gas O ₂ / (N ₂
The appropriate value of + O ₂ ) was examined as follows from the viewpoint of the signal characteristics of the reproduced signal and the margin of the power of the laser beam irradiated during recording (hereinafter, referred to as recording power).
That is, in the present invention, the reason why the appropriate ratio of the O ₂ gas becomes the above-mentioned equation (31) is based on the following experimental results.

2-1 Signal Characteristics of Reproduced Signal and O ₂ / (N ₂
+ O ₂ ) First, at the time of forming the recording film, the mixture ratio of N ₂ gas and O ₂ gas to Ar gas (N ₂ + O ₂ ) / Ar is determined using a material made of Ge ₂ Sb ₂ Te _5. 10%, and the film formation rate is 0.1%.
And 42 nm / s, by changing the N ₂ gas and O ₂ occupying the gas O ₂ ratio of gas O ₂ / (N ₂ + O ₂₎ to 0% to 100%, except that the recording layer was formed by sputtering A double-sided optical disk was manufactured in the same manner as in the experiment of FIG.

Then, after performing an initialization process on this optical disk, the light emission pulse similar to that shown in FIG.
Recording was repeated 20,000 times, and the jitter value of the reproduced signal was measured. The result is shown in FIG. In FIG. 13, the horizontal axis represents the ratio O ₂ / (N ₂ + O ₂ ) of the O ₂ gas in the mixed gas composed of the N ₂ gas and the O ₂ gas, and the vertical axis represents 20.
The jitter value of the reproduced signal after recording 000 times was taken. Note that 0% on the horizontal axis in FIG. 13 indicates that the atmosphere at the time of forming the recording film does not contain O ₂ gas.

Here, the media reference value is 12.5% as a jitter value at which a good reproduced signal can be obtained after a large number of repeated recordings such as 20,000 times.

[0075] As apparent from the results of FIG. 13, with the ratio of O ₂ gas is increased, there is a tendency that the jitter value of the reproduced signal gradually decreases, the proportion of O ₂ gas is 10% or more It was found that the jitter value of the reproduced signal was 12.5% or less, and that a satisfactory reproduced signal could be sufficiently obtained even after repeated recording many times.

2-2 Recording Power Margin and O ₂ / (N ₂
+ O ₂₎ relationship between the first, after preparing the optical disc in the same manner as the experiment of FIG. 13, an acceleration test was carried out the optical disc was left for 100 hours at a temperature 90 ° C. in a constant temperature bath.

Thereafter, recording was repeatedly performed on the same track of the optical disk twice, and a recording power margin at that time was obtained. The result is shown in FIG. Here, 10% is set as a media reference value as a jitter value at which a good reproduction signal is obtained after a small number of repeated recordings such as two.

The recording power margin Pw is defined as follows, with a jitter value of 10% of the reproduced signal as a threshold level. That is, the recording power margin Pw is repeated twice recorded minimum and maximum values, respectively P _min and P _{m ax} recording power jitter value of the reproduced signal can be recorded so as to be 10% after
Where (P _max −P _min ), which is the difference between the maximum value and the minimum value of the recording power, is divided by (P _max + P _min ) / 2, which is the average of the maximum value and the minimum value of the recording power. That is, a value represented by the following equation (35) is used.

Pw = ( _{Pmax− Pmin} ) / {( _Pmax + _Pmin ) / 2} (35) As is clear from the results of FIG. 14, as the ratio of O ₂ gas increases, , the recording power margin is reduced, the ratio of O ₂ gas occupying the N ₂ gas and O ₂ gas O ₂ / (N ₂ +
If O ₂ ) is greater than 60%, the recording power margin is 10
% Or less, and it is considered that the optical disc will not be able to perform sufficient recording when the power of the recording laser fluctuates or the environment changes.

2-3 Signal Characteristics of Reproduction Signal and Recording Power
-Appropriate value of O ₂ / (N ₂ + O ₂ ) from the viewpoint of margin From the results of FIGS. 13 and 14, the jitter value of the reproduced signal after 20,000 repetitive recordings is set to a good signal detection level and recorded. In order to secure the minimum recording power margin necessary for performing sufficient recording even when laser power fluctuation occurs, it is necessary to set N
₂ gas and ratio of O ₂ gas to O ₂ gas O ₂ / (N ₂ +
O ₂ ) was found to be preferably 10% or more and 60% or less.

As described above, in the optical recording medium to which the present invention is applied, the phase change material contains a GeSbTe alloy, and the recording film 4 made of this phase change material uses N ₂ gas and O ₂ gas. It is formed by sputtering in a contained Ar gas atmosphere.

Further, as is apparent from the results shown in FIGS. 4 to 14, the optical recording medium to which the present invention is applied
Recording film 4, under an Ar gas atmosphere containing N ₂ gas and O ₂ gas, the mixing ratio of N ₂ gas and O ₂ gas to the Ar gas (N ₂ + O ₂₎ / Ar as Y [%], the N ₂ occupying the gas and O ₂ gas O ₂ ratio of gas O ₂ / (N ₂ + O ₂₎
Is defined as Z [%] and the film forming speed is defined as X [nm / s], the film may be formed by sputtering under the conditions satisfying the following formulas (36), (37) and (38). It turned out to be favorable.

Y ≧ 2.3X + 1.0 (36) Y ≦ 12.8X + 16.7 (37) 10 ≦ Z ≦ 60 (38) Light to which the present invention is applied as described above The recording medium is a recording film 4
Is defined, the Ge forming the recording film 4 is
The SbTe alloy is suitably nitrided and oxidized, whereby the physical properties of the recording film 4 are optimized with respect to the recording / reproducing characteristics, and the repetitive recording durability is further improved. Thereby, in the optical recording medium to which the present invention is applied, a local deterioration phenomenon of the reproduction signal such as a local increase in the jitter value of the reproduction signal which is observed after performing the recording several to several tens of times is minimized, and A good reproduction signal can be obtained even if recording is repeated several tens of thousands of times. As a result, the optical recording medium to which the present invention is applied can always obtain stable and good recording / reproducing characteristics even after repeated recording.

[0084] 3. At the composition of the phase change material constituting the recording film, the recording film 4 used in the present invention has a composition ratio of Ge—Sb—Te constituting the recording film 4 shown in FIG.
In the (Ge, Sb, Te) ternary phase diagram shown in FIG.
Point J (26.0, 19.2, 54.8), Point K (21.
0, 21.0, 58.0), point L (14.3, 28.
6,57.1), point M (21.6, 24.4, 54.
0).

As described above, G constituting the recording film 4
The reason for defining the composition ratio of e-Sb-Te is based on the following experimental results. Hereinafter, this experiment will be described in detail.

3-1 Ternary State of (Ge, Sb, Te)
In the figure, on a straight line connecting Ge ₅₀ Te ₅₀ and Sb ₄₀ Te ₆₀
Study of the composition First, the first dielectric film 3 made of ZnS-SiO ₂ having a thickness of 120nm on the substrate 2 was formed by sputtering.

Next, on the first dielectric film 3, a mixture ratio of N ₂ gas and O ₂ gas to Ar gas (N ₂ + O ₂ ) /
The Ar was 10%, the proportion occupied by the O ₂ gas O ₂ / (N ₂ +
Under an atmosphere in which O ₂ ) was set to 20%, the deposition rate was set to 0.42.
A recording film 4 made of GeSbTe having a thickness of 25 nm was formed by sputtering at nm / s.

At this time, when this recording film 4 is formed,
The target is formed by sputtering using a target composed of Ge ₂ Sb ₂ Te ₅ , a target composed of Ge, a target composed of Sb, and a target composed of Te.

Here, first, in the ternary phase diagram of (Ge, Sb, Te), as shown in FIG.
A phase change optical disk having a recording film having a composition on a straight line 11 connecting Ge ₅₀ Te ₅₀ and Sb ₄₀ Te ₆₀ was studied with emphasis on 2,5). Specifically, while maintaining the film formation rate ratio between the Ge target and the Te target at 1, Ge ₂ S
A recording film 4 having a composition between Ge ₅₀ Te ₅₀ and Ge ₂ Sb ₂ Te ₅ in FIG. 16 was formed by co-sputtering a b ₂ Te ₅ target.

Then, on this recording film 4, a film thickness of 15 nm
A second dielectric film 5 made of ZnS-SiO _2, thickness 1
A light reflecting film 6 of an Al alloy having a thickness of 50 nm was sequentially formed by sputtering, and thereafter, a protective film 7 was formed by applying an ultraviolet curable resin or the like on the light reflecting film 6 to obtain the phase change optical disk 1.

Finally, two phase-change optical disks are manufactured, and each of the light-reflecting films faces inward.
These phase change optical disks were adhered to each other via an adhesive to obtain a double-sided phase change optical disk having a diameter of 120 mm and a thickness of 1.2 mm.

In the same manner, a phase change optical disk in which only the composition of the recording film 4 was changed was manufactured. Specifically, by co-sputtering a Ge ₂ Sb ₂ Te ₅ target while maintaining a film forming rate ratio between the Sb target and the Te target at 0.67, Sb ₄₀ Te ₆₀ and Ge ₂ in FIG.
A recording film 4 having a composition between Sb ₂ Te ₅ was formed.

For the phase-change optical disk having the recording film 4 having the composition represented by the point on the straight line 11 manufactured in this manner, using the light emission pattern shown in FIG. 3 under the same conditions as in FIG. Recording was performed once and the jitter value of the reproduced signal was measured.

FIG. 17 shows the result. In FIG. 17, the abscissa indicates the ratio of Ge in the composition on the straight line 11 connecting Ge ₅₀ Te ₅₀ and Sb ₄₀ Te ₆₀ , and the ordinate indicates the jitter value of the reproduced signal after recording once. Note that point J, point L, and point C in FIG. 17 correspond to point J (26.0, 19.2, 5
4.8), point L (14.3, 28.6, 57.1), and point C (2, 2, 5).

From the result of FIG. 17, (Ge, Sb, Te)
J (26.0, 19.2, 5) in the ternary phase diagram of
In a composition having a Ge content higher than 4.8), the jitter value becomes 10% or more, and the point L (14.3, 28.6, 5) is obtained.
Even in a composition having a lower Ge content than 7.1),
It was found that the jitter value was 10% or more. Therefore, it has been found that the composition on the straight line 11 connecting Ge ₅₀ Te ₅₀ and Sb ₄₀ Te ₆₀ is preferably a composition in a range connecting the point J and the point L as shown in FIG.

3-2 Ternary State of (Ge, Sb, Te)
In the figure, more Te is included than point C (2, 2, 5).
Examination of Composition Having Next, a phase change optical disc having a recording film having a composition containing more Te than point C (2, 2, 5) was examined. Specifically, a Ge ₂ Sb ₂ Te ₅ target and a Te ₂
By co-sputtering with a target, a phase-change optical disc having a recording film 4 having a composition on a straight line 12 from point C was produced.

With respect to the phase-change optical disk having the recording film 4 having the composition represented by the point on the straight line 12 thus manufactured, the jitter value of the reproduced signal after one-time recording is determined in the same manner as in FIG. It was measured.

FIG. 18 shows the result. In FIG. 18, the abscissa indicates the ratio of Te in the composition on the straight line 12 connecting Ge ₂ Sb ₂ Te ₅ and Te, and the ordinate indicates the jitter value of the reproduced signal after recording once. Note that points C and K in FIG.
Are the points C (2, 2, 5) and K (21.0,
21.0, 58.0).

From the results of FIG. 18, as shown in FIG.
In order for the jitter value to be 10% or less, the point C (2, 2,
It has been found that a composition in the range connecting 5) to the point K (21.0, 21.0, 58.0) is preferable.

3-3 Ternary State of (Ge, Sb, Te)
In the figure, Sb is contained more than point C (2, 2, 5).
Examination of Composition Having Next, a phase change optical disc having a recording film having a composition containing a larger amount of Sb than point C (2, 2, 5) was examined. Specifically, a Ge ₂ Sb ₂ Te ₅ target and Sb
The point C is obtained by co-sputtering with the target.
A phase change optical disk having a recording film 4 having a composition on a straight line 13 was manufactured from the above.

With respect to the phase-change optical disk having the recording film 4 having the composition represented by the point on the straight line 13 thus manufactured, the jitter value of the reproduced signal after one-time recording was measured in the same manner as in FIG. did.

FIG. 19 shows the result. In FIG. 19, the abscissa indicates the ratio of Sb in the composition on the straight line 13 connecting Ge ₂ Sb ₂ Te ₅ and Sb, and the ordinate indicates the jitter value of the reproduced signal after recording once. Note that points M and C in FIG.
Corresponds to the point M (21.6, 24.4, 54.
0) and point C (2, 2, 5).

From the results of FIG. 19, as shown in FIG.
In order for the jitter value to be 10% or less, the point M (21.6,
24.4, 54.0) and point C were found to be preferable.

3-4 Preferred Set of Recording Film in the Present Invention
From the above results, the phase change optical disk 1 to which the present invention is applied
In FIG. 15, as shown in FIG. 15, the GeSbTe composition ratio of the recording film made of GeSbTe is changed to the point J (26.0, 1).
9.2, 54.8), point K (21.0, 24.4, 5)
8.0), a composition within a region surrounded by a point L (14.3, 28.6, 57.1), and a point M (21.6, 21.6, 54.0). did.

As described above, in the phase-change optical disc 1 to which the present invention is applied, the composition of the phase-change material constituting the recording film 4 is defined, so that the recording film 4 has more repeated recording durability and recording / reproducing characteristics. It is optimized and a stable and good reproduction signal can be effectively obtained even after repeated recording.

[0106] 4. Examination of suitable film thickness of recording film By the way, the film thickness of the recording film 4 in the present invention is 18 nm.
It is preferably about 30 nm. This is based on the following experimental results.

4-1 Suitable Recording Film in the Present Invention
The thickness examination results First, a first dielectric film 3 made of ZnS-SiO ₂ having a thickness of 120nm on the substrate 2 was formed by sputtering.

Then, Ge is formed on the first dielectric film 3.
_The recording film 4 made of ₂ Sb ₂ Te _{5 is} coated with N ₂
Mixing ratio of gas and O ₂ gas (N ₂ + O ₂ ) / Ar is 10%
And then, the ratio of O ₂ gas occupying the N ₂ gas and O ₂ gas O ₂ /
In an atmosphere in which (N ₂ + O ₂ ) was 20%, the film was formed by sputtering at a film formation rate of 0.42 nm / s. At this time, the recording film 4 was formed by changing the thickness of the recording film 4 to 15 nm to 40 nm, and a plurality of substrates 2 having different thicknesses of the recording film 4 were obtained.

Next, on the recording films 4 having different thicknesses, a second dielectric film 5 made of ZnS-SiO _{2 having} a thickness of 15 nm and a light reflecting film 6 made of an Al alloy having a thickness of 150 nm are formed. Then, the protective film 7 was formed by applying an ultraviolet curable resin on the light reflecting film, thereby obtaining the phase change optical disk 1.

After initializing a plurality of phase change optical discs having different thicknesses of the recording film 4 thus obtained, a random EFM signal is repeatedly recorded using a light emission pattern as shown in FIG. The jitter value of the reproduced signal was measured. At this time, the linear velocity was set to 4.8 m / s, and the recording power Ph, the erasing power Pl, and the cooling power Pc were set to 1
The power was set so as to minimize the jitter of the reproduced signal after the recording was performed multiple times.

When such an experiment was conducted, the recording film 4
In a phase-change optical disk having a film thickness of less than 18 nm, the recording quality of the recording film 4 is weakened.
However, when a laser beam having a high power of 15 mW is used, there is a disadvantage that recording cannot be repeated.
On the other hand, in the phase-change optical disc 1 in which the thickness of the recording film 4 is larger than 30 nm, the jitter value of the reproduced signal after 10000 recordings was 12.5% or more, and the repetitive recording durability was insufficient. Therefore, the thickness of the recording film 4 is 18 n
It can be said that it is preferably from m to 30 nm.

In the present invention, the first dielectric film 3 is formed on the substrate 2. The first dielectric film 3 includes a recording film 4
It is formed to exhibit an oxidation preventing effect and an amplifying effect by multiple interference of laser light.

[0113] As the material of the first dielectric film 3, for _{example, ZnS, SiO X, Al 2} O 3, ZrO 3, Ta
₂ O ₅ , Si ₃ N ₄ , SiN _x , AlN _x , MoO ₃ , WO ₃ ,
Examples include ZrO ₂ , BN, TiN, ZrN, PbF ₂ , and MgF _2. These materials may be used alone or as a mixture. Among them, a preferable material is a material containing at least ZnS, and more preferably, a material containing ZS.
nS—SiO ₂ .

The thickness of the first dielectric film 3 is 80 n
It is preferably from m to 140 nm. This is based on the experimental results shown below.

First, a first dielectric film 3 made of ZnS—SiO ₂ was formed on a substrate 2 by sputtering.
At this time, the thickness of the first dielectric film 3 is set to 70 nm to 150 nm.
By changing the thickness to 1 nm, a plurality of substrates 2 on which first dielectric films 3 having different thicknesses were formed were obtained.

Next, a mixture ratio of N ₂ gas and O ₂ gas to Ar gas (N ₂ + O ₂ ) / Ar was set to 10% on each of the first dielectric films 3 having different thicknesses. , N ₂ gas and O ₂ ratio O ₂ / a O ₂ gas occupying the gas (N ₂ + O ₂₎ atmosphere was 20%, the deposition rate 0.42 nm / s
The recording film 4 made of Ge ₂ Sb ₂ Te ₅ has a thickness of 25
nm was formed by sputtering.

Then, a film thickness of 15 nm is formed on each of these recording films.
A second dielectric film 5 made of ZnS-SiO _2, thickness 1
A light reflecting film 6 made of an Al alloy having a thickness of 50 nm was sequentially formed by sputtering, and then a UV-curable resin was applied and formed on the light reflecting film 6 to form a protective film 7.

After initializing the phase-change optical disk thus obtained, the groove reflectance was measured. Further, using a light emission pattern as shown in FIG.
The random EFM signal was repeatedly recorded, and the jitter value of the reproduced signal was measured. At this time, the linear velocity was set to 4.8 m / s, and the recording power Ph, the erasing power Pl, and the cooling power P
c was set to a power such that the jitter of the reproduced signal after one recording was minimized.

As a result of such an experiment, in the phase change optical disk 1 in which the thickness of the first dielectric film 3 was smaller than 80 nm, the groove reflectance was low, and a sufficient reproduction signal could not be obtained. Further, the thickness of the first dielectric film 3 is 1
For the phase change optical disk 1 larger than 40 nm, 100
11. The jitter value of the reproduced signal after recording repeatedly 00 times is 12.
5% or more, and the repetitive recording durability was insufficient. Therefore, the phase change optical disk 1 to which the present invention is applied
Then, the thickness of the first dielectric film 3 is 80 nm to 140 nm.
Was found to be preferable.

Note that the first dielectric film 3 is formed, for example, by
Evaporation method, ion beam sputtering, DC sputtering, RF
It can be formed using a conventionally known method such as a sputtering method such as sputtering.

The second dielectric film 5 is formed on the recording film 4 by using the same material as the first dielectric film 3 and using the same method as the first dielectric film 3. Like the first dielectric film 3, the second dielectric film 5 is formed for the effect of preventing the recording film 4 from being oxidized and the effect of amplifying the laser light by multiple interference.

The film thickness of the second dielectric film 5 is 1
0 nm to 30 nm is preferred. This is because, when the thickness of the second dielectric film is smaller than 10 nm, heat generated by the laser light is easily conducted to the light reflection film 6 and the function of preventing the intrusion of water from the outside is reduced. Because it becomes. If the film thickness of the second dielectric film 5 is larger than 30 nm, the heat of the recording film 4 heated by the laser beam becomes difficult to conduct to the light reflection film 6, and when the recording and reproduction are repeatedly performed. This is because the recording film 4 significantly deteriorates.

Then, a light reflection film 6 is formed on the second dielectric film 5. The light reflection film 6 functions as a reflection layer that reflects light incident from the substrate 2 and also functions as a heat sink layer that prevents excessive accumulation of heat in the recording film 4.

As a material of the light reflecting film 6, it is desirable to use a metal element, a metalloid element, a semiconductor element and a compound thereof alone or in combination.
Metal elements such as 1, Au, Ni, Fe, and Cr, and alloys thereof.

The light reflecting film 6 has a thickness of 50 nm to 3 nm.
It is preferably 00 nm. The thickness of the light reflection film 6 is 5
If the thickness is smaller than 0 nm, the light reflection film 6 has a structure in which heat is hardly released, and the deterioration of the recording film 4 progresses quickly when recording and reproduction are repeatedly performed. Further, the thickness of the light reflecting film 6 is 300
If it is larger than nm, there is a drawback that the production time becomes longer and productivity is not preferable. Also, this light reflection film 6
As a method for forming the above, for example, a conventionally known method such as a vapor deposition method, a sputtering method such as ion beam sputtering, DC sputtering, and RF sputtering can be used.

The protection film 7 is formed on the light reflection film 6. The protective film 7 is formed, for example, by applying a resin such as an ultraviolet curable resin by spin coating, or by bonding a resin plate, a glass plate, a metal plate, or the like to the light reflection film 6 via an adhesive.

The phase change optical disk has a diameter of 1
Two substrates with a thickness of 20 ± 0.3 mm and a thickness of 0.6 ± 0.03 mm were bonded together, and a functional film such as a recording film was formed on both surfaces, and the track pitch was set to 0.8 ± 0.01 μm. And the ratio λ / of the numerical aperture NA to the wavelength λ of the light source.
NA is (1.083-0.086) μm to (1.083
A double-sided phase-change optical disc has been proposed in which a recording capacity is set to 3.0 GB / side by groove recording with an optical system of +0.167) μm. The present invention can be suitably applied to such a phase change optical disk.

The phase change optical disk 1 configured as described above is manufactured, for example, as follows.

First, a substrate 2 made of polycarbonate having predetermined grooves formed by injection molding is manufactured.
Then, on this substrate 2, a first layer made of ZnS—SiO _{2 is formed} .
Is formed by the RF sputtering method.

Next, GeSbTe is formed on the first dielectric film 3.
A recording film 4 made of an alloy is formed by a DC sputtering method.
At this time, in particular, in the method of manufacturing an optical recording medium to which the present invention is applied, when the recording film 4 is formed, a GeSbTe alloy is used as a phase change material, and an Ar ₂ gas containing an N ₂ gas and an O ₂ gas is used. The film is formed by sputtering in a gas atmosphere.

Here, when the recording film 4 is formed, an Ar gas atmosphere containing an N ₂ gas and an O ₂ gas is used.
Mixing ratio of N ₂ gas and O ₂ gas to gas (N ₂ + O ₂ )
/ Ar is Y [%], and O occupies N ₂ gas and O ₂ gas.
_When the ratio O ₂ / (N ₂ + O ₂ ) of the _two gases is Z [%] and the film formation rate is X [nm / s], the following equations (39), (40) and (41) are obtained. It is preferable to form a film by sputtering under conditions that satisfy the conditions.

Y ≧ 2.3X + 1.0 (39) Y ≦ 12.8X + 16.7 (40) 10 ≦ Z ≦ 60 (41) Light to which the present invention is applied as described above According to the method of manufacturing the recording medium, the conditions for forming the recording film 4 are defined, so that the GeSbTe alloy forming the recording film 4 is suitably nitrided and oxidized. Thereby, the physical properties of the recording film 4 are optimized with respect to the recording / reproducing characteristics, and the repetitive recording durability is further improved. Therefore, according to the method for manufacturing an optical recording medium to which the present invention is applied, the local reproduction signal deterioration phenomenon seen after performing repetitive recording several to several tens of times is suppressed as much as possible, and the repetition is repeated tens of thousands of times or more. A good reproduction signal is obtained even when recording is performed, and as a result, an optical recording medium that always has stable and good recording and reproduction characteristics even after repeated recording can be provided.

Here, the film forming speed X is 0.1 nm
/ S or more and 5.0 nm / s or less.
As described above, according to the method for manufacturing an optical recording medium according to the present invention, the recording / reproducing characteristics of the recording film 4 are further optimized by setting the film forming speed within the above range, and the quality is improved even after repeated recording. It is possible to more effectively provide an optical recording medium having excellent recording / reproducing characteristics.

The composition of the recording film 4 thus formed is represented by a point J (26.0, 19.2, 54.8) in the ternary phase diagram of (Ge, Sb, Te). Point K (21.
0, 21.0, 58.0) and the point L (14.3, 28.
6,57.1) and the point M (21.6, 24.4, 54.
0) and GeSbT having a composition in a region surrounded by
e alloy.

By forming the recording film 4 having such a composition, the recording / reproducing characteristics of the recording film 4 are optimized, and an optical recording medium in which the deterioration of the reproduced signal is suppressed as much as possible after repeated recording is obtained.

Next, on this recording film 4, ZnS-SiO
_{A second} dielectric film 5 of 2 is formed by RF sputtering. Then, a light reflection film 6 is formed on the second dielectric film 5 using an Al target.

Next, an ultraviolet curable resin is applied and formed on the light reflecting film 6 by spin coating, and finally, the phase change optical disk 1 to which the present invention is applied is manufactured. In order to produce a double-sided phase-change optical disc 10 as shown in FIG. 2, for example, two phase-change optical discs 1 are produced, and these two phase-change optical discs are each provided with a light reflection film 6. It can be manufactured by pasting together via an adhesive so as to face each other inward.

The phase change optical disk 1 configured as described above undergoes an initialization process as described below, and recording, erasing, and reproduction of an information signal are performed as described below.

First, as described above, in the phase change optical disk 1, the first dielectric film 3, the recording film 4, the second dielectric film 5, the light reflecting film 6, and the protective film 7 are sequentially formed on the substrate 2. After the formation, an initialization process for initializing the recording film 4 is performed.

This initialization process is to make the recording film 4 a uniform crystalline state before the information signal is recorded on the recording film 4. Specifically, the phase change optical disk 1
Is uniformly irradiated with a predetermined laser beam. At this time, the temperature of the recording film 4 is raised below the melting point of the constituent phase change material and above the crystallization temperature. After that, the recording film 4 of the phase change optical disk 1 is cooled to be brought into a uniform crystalline state and initialized.

Next, the phase-change optical disk 1 thus initialized is mounted on a recording / reproducing apparatus, and is recorded, erased and reproduced while being rotated at a predetermined linear velocity.

First, when recording an information signal on the phase-change optical disc 1, a laser beam having a strong power is incident on the recording film 4 from the substrate 2 side. As a result, the portion of the recording film 4 irradiated with the laser light is rapidly heated to a temperature equal to or higher than the melting point, and then rapidly cooled to be in an amorphous state which is an amorphous state. As described above, in the phase-change optical disc 1, the information signal is recorded on the recording film 4 in a crystalline state as a recording mark made of a phase-change material in an amorphous state.

When erasing the information signal recorded on the phase-change optical disc 1, a laser beam weaker than the laser beam irradiated at the time of recording is irradiated from the substrate 2 side at least on the recording mark. As a result, the portion of the recording film 4 irradiated with the laser beam is heated to a temperature higher than the crystallization temperature and lower than the melting point, and then gradually cooled to a crystalline state regardless of the previous state. Thus, in the recording film 4, the information signal is erased by converting the recording mark in the amorphous state as the information signal into the crystalline state.

When reproducing the information signal written from the phase-change optical disc 1 on which the information signal has been recorded and / or erased, the phase change of the recording film 4 relative to the recording film 4 is performed. A light beam having such a small power that does not occur is made incident from the substrate 2 side, and the return light of this light beam is received.

In the phase change optical disk 1, the reflectance when the recording film 4 is in a crystalline state is higher than the reflectance when the phase change recording film 4 is in an amorphous state. Therefore, the recording / reproducing apparatus reproduces the information signal by receiving the return light from the recording film 4 and detecting the difference in the reflectance between the crystalline state and the amorphous state of the recording film 4.

<Second Embodiment> The phase-change optical disc according to the present embodiment is the same as the phase-change optical disc 1 shown in FIG.
Similarly, on the substrate 2, the first dielectric film 3, the recording film 4,
The second dielectric film 5, the light reflection film 6, and the protection film 7 are laminated in this order.

Here, the phase change optical disk according to the present embodiment is different only in the configuration of the recording film 4, and the constituent films other than the recording film 4 are the same as the substrate 2 and the first , The second dielectric film 5, the light reflecting film 6, and the protective film 7 have substantially the same configuration. Therefore, in the following description, the description of each of the constituent films will be omitted, and only the recording film 4 will be described.

The recording film 4 is made of a phase change material which reversibly changes its phase between a crystalline state and an amorphous state by irradiation with a light beam such as a laser beam. This is an optical recording layer on which information signals can be written, erased, and reproduced.

In particular, the phase change material of the recording film 4 in the present invention is a chalcogen compound made of a Ge—Sb—Te alloy. The recording film 4 has a thickness of 18 nm to 3 nm.
Preferably, it is 0 nm.

[0150] The recording film 4 in the present invention under an Ar gas atmosphere containing O ₂ gas, the mixing ratio O ₂ / Ar between the O ₂ and Ar gases and Y [%], the film formation rate To X
When [nm / s] is set, the film is formed by sputtering under the conditions satisfying the following expressions (42) and (43).

Y ≧ 2.3X + 1.0 (42) Y ≦ 5.5X + 2.7 (43) Furthermore, the film formation rate X is 0.1 nm / s or more and 5.0.
It is preferably at most nm / s. That is, it is preferable that X satisfies the following expression (44).

[0152] 0.1 ≦ X ≦ 5 ··· (44 ) The above mixing ratio O ₂ / Ar is a flow ratio of O ₂ and Ar, in other words, the volume ratio of O ₂ and Ar in the atmosphere Is shown.

1. Deposition speed X and atmosphere during recording film deposition
As described above, in the optical recording medium to which the present invention is applied and the method for manufacturing the same, when forming the recording film 4, the mixture ratio Y [%] of the O ₂ gas and the Ar gas and the Film speed X [nm
/ S] is defined as in the above equations (42), (43) and (44) based on the following experimental results. Hereinafter, this experiment will be described in detail.

1-1 Atmosphere Conditions During Recording Film Formation
Relationship between the signal characteristics of the reproduced signal is first to prepare a phase-change optical disk as follows.

First, the diameter is 120 mm and the thickness is 0.6 m
m substrate 2 was prepared. Then, a film having a thickness of 9
The first dielectric film 3 made of ZnS-SiO ₂ of 0nm was formed by sputtering.

Next, Ge _{2 is} deposited on the first dielectric film 3.
Using a target made of Sb ₂ Te ₅ , the film formation rate was set to 0.42 nm / s, and a 25 nm-thick Ge film was formed by sputtering in an Ar gas atmosphere mixed with O ₂ gas.
A recording film 4 made of -Sb-Te was formed by sputtering.

[0157] At this time, as an Ar gas atmosphere of a mixture of O ₂ gas, the mixing ratio O ₂ / Ar of the O ₂ gas and Ar gas 0
%, And a plurality of recording films were formed under each condition. However, the above mixing ratio O ₂ / Ar
Of 0% indicates an Ar gas atmosphere containing no O ₂ gas, and is not a recording film forming condition in the manufacturing method to which the present invention is applied.

Next, on the recording film 4 formed under each condition, a second dielectric film 5 made of ZnS-SiO ₂ with a thickness of 15 nm, and a light reflection film 6 made of an Al alloy with a thickness of 150 nm Were sequentially formed by sputtering, and a UV-curable resin was applied on the light reflecting film 6 to form a protective film 7, whereby the phase-change optical disc 1 was manufactured.

Then, the two phase-change optical disks 1 thus manufactured are manufactured two by two, and the two phase-change optical disks are bonded with an adhesive 9 so that the light reflection films 6 face each other inward. In other words, as shown in FIG.
A 2-mm double-sided phase change optical disk 10 was produced. The phase change optical disks 1 and 10 have a track pitch of about 0.8 μm.

A plurality of phase-change optical disks manufactured by changing the film forming conditions as described above were subjected to an initialization process for irradiating a strong laser beam to crystallize the recording film 4.

Then, for these phase-change optical disks after the initialization, a random EFM signal was generated by using a light emission pattern as shown in FIG.
As recorded. Here, in FIG. 3, the recording power is Ph
, The erasing power Pl, and the cooling power Pc. In the light emission pattern in FIG. 3, one clock is 1T, and the pulse length of one light emission pulse is 13 ns.

At this time, the linear velocity was 4.8 m / s, the recording power Ph was 140 mW, the erasing power Pl was 5.6 mW, and the cooling power Pc was 1.5 mW.
Was used. The recording / reproducing apparatus is equipped with a light source for generating a laser beam having a wavelength of 650 nm.

Under these conditions, recording was repeatedly performed 20,000 times on each phase change optical disk.

In order to evaluate the relationship between the mixed gas condition of the O ₂ gas and the Ar gas at the time of forming the recording film and the signal characteristics of the reproduced signal, these phase change optical disks after 20,000 repetitive recordings were used. The jitter value of the reproduced signal after repeated recording was measured.

FIG. 20 shows the result. In FIG. 20, the horizontal axis indicates the mixing ratio O ₂ / Ar of O ₂ gas and Ar gas, and the vertical axis indicates the jitter value of the reproduced signal when the same track is repeatedly recorded 20,000 times. Here, the media evaluation reference value is 12.5% as a jitter value at which error correction is possible.

[0166] As apparent from the results of FIG. 20, the jitter value, when the mixing ratio O ₂ / Ar is 0%, that O ₂
15.8% when gas is not mixed in Ar gas
And decreases as the proportion of O ₂ gas increases, and becomes minimum when the mixture ratio O ₂ / Ar is 1.5% to 4%. When the mixing ratio O ₂ / Ar further increases, the jitter value gradually increases.

Therefore, as shown in FIG. 20, in order to reduce the jitter value of the reproduced signal after repeated recording to 12.5% or less, at which the error can be corrected, the mixing ratio O ₂ / Ar is 1.5.
% Of the recording film was found to be desirable in an Ar gas atmosphere of at least%.

1-2 Atmosphere Conditions and Each Data at Recording Film Formation
The relationship between the groove reflectance of the disk then to evaluate the atmospheric conditions of a mixed gas of O ₂ gas and Ar gas during recording film deposition, the relationship between the reflectance in the groove of the disk, as described above The reflectivity in the groove was measured for each phase-change optical disk after the recording film was formed and initialized while changing the atmosphere conditions at the time of forming the recording film.

FIG. 21 shows the result. In FIG. 21, the horizontal axis represents the mixture ratio O ₂ / Ar of the O ₂ gas and the Ar gas, and the vertical axis represents the reflectance in the groove.

As is clear from the results shown in FIG. 21, the reflectance in the groove monotonously decreases as the mixing ratio O ₂ / Ar increases. When the mixture ratio O ₂ / Ar becomes 5.0% or more, the reflectance in the groove becomes 11%.
% Or less, which causes a problem that a sufficient reproduction output, in other words, a sufficient degree of modulation cannot be obtained.

Therefore, as shown in FIG. 21, it was found that the mixture ratio O ₂ / Ar in the atmosphere at the time of forming the recording film was required to be 5.0% or less in order to ensure a sufficient reproduction output. did.

1-3 Both Signal Characteristics and Groove Reflectance
As described above, based on the results shown in FIGS. 20 and 21, in the optical recording medium to which the present invention is applied and the method for manufacturing the same, the film forming speed of the recording film is 0.42 nm / s. At this time, in order to satisfy both the conditions of the jitter value of the reproduced signal and the reflectivity at the groove, the mixing ratio O ₂ / Ar is 1.5% to 5.0%.
It turned out that it was necessary to form the recording film in an r gas atmosphere.

The results of FIGS. 20 and 21 are as follows.
It is intended for an optical disc on which a recording film is formed at a film forming speed of 0.42 nm / s. Therefore, in order to obtain the same characteristics as those of the optical disks of FIGS. 20 and 21 when the film forming speed is changed, it is necessary to change the mixing ratio O ₂ / Ar of the O ₂ gas and the Ar gas.

1-4 Atmosphere in the case of changing the film forming rate
Relationship between ambient conditions and signal characteristics and groove reflectivity Then, when the film forming speed of the recording film is changed, the mixing ratio O satisfying both the conditions of the jitter value of the reproduced signal and the reflectivity at the groove is satisfied. ₂ / Ar was studied.

Here, the applied voltage of the target made of Ge ₂ Sb ₂ Te ₅ was changed, and the film formation rate of the recording film was set to 0.1.
As described above, except that the recording film was formed under the condition that the mixing ratio O ₂ / Ar of O ₂ gas and Ar gas was changed from 0% to 5%. Was prepared, and the jitter value after 20,000 repetitive recordings was measured in the same manner as in the experiment of FIG. The result is shown in FIG. Further, the film forming speed of the recording film is set to 0.1 nm / s,
The reflectivity of the groove after the initialization of the optical disk manufactured by changing the atmosphere conditions at the time of forming the recording film as described above was measured in the same manner as in the experiment of FIG. The result is shown in FIG.

Similarly, the film forming speed of the recording film was set to 1.6 n.
m / s, and O ₂ gas and A
A phase-change optical disk was manufactured under the condition that the mixing ratio O ₂ / Ar of the r gas was changed from 0% to 20%, and the jitter value of the reproduced signal after 20,000 repetitive recordings and the reflectivity of the groove after initialization were measured. It was measured. The results are shown in FIGS. 24 and 25, respectively.

Similarly, the film forming speed of the recording film was set to 5.0 nm / s, and the atmosphere for forming the recording film was O _2.
The mixing ratio O ₂ / Ar gas and Ar gas to prepare a phase-change optical disk under the conditions varied from 0% to 40%, 200
The jitter value of the reproduced signal after the recording was repeated 00 times and the reflectivity of the groove after the initialization were measured. The results are shown in FIGS. 26 and 27, respectively.

From the results shown in FIGS. 22, 24 and 26, the film formation rates were set to 0.1 nm / s, 1.6 nm / s,
In an optical disc on which a recording film is formed at 5.0 nm / s, the mixing ratio O ₂ / Ar at which the jitter value of the reproduced signal is 12.5% or less is 1%, 4%, or 12% or more, respectively. all right.

From the results shown in FIGS. 23, 25 and 27, the film formation rates were set to 0.1 nm / s, 1.6 nm / s,
In an optical disk on which a recording film is formed at a thickness of 5.0 nm / s, a mixture ratio O ₂ / A at which the groove reflectance becomes 11% or more is obtained.
r was found to be 3%, 12%, and 30% or less, respectively.

1-5 Both Signal Characteristics and Groove Reflectance
As discussed above recording film deposition conditions satisfying the square condition, Figure 20, Figure 22, from the results of FIGS. 24 and 26, the deposition rate 0.42 nm / s, 0.1 nm /
In an optical disc on which a recording film is formed at s, 1.6 nm / s, and 5.0 nm / s, the mixing ratio O ₂ / Ar at which the jitter value of the reproduced signal is 10% or less is 1.5 or less, respectively.
%, 1%, 4%, and 12%. The results are shown in FIG. 28 with the abscissa plotting the film forming rate and the ordinate plotting the mixing ratio O ₂ / Ar, and the result is a straight line α.

In FIG. 28, the film formation rate on the horizontal axis is X [nm /
s], and the mixing ratio O ₂ / Ar on the vertical axis is Y [%].
Then, the straight line α is represented by Y = 2.3X + 1.0.
Here, the area below the straight line α is an area where the jitter value of the reproduction signal becomes 12.5% or more and a good reproduction signal cannot be obtained.

On the other hand, as described above, FIGS.
From the results of FIGS. 25 and 27, the film formation rate was set to 0.42 nm.
/ S, 0.1 nm / s, 1.6 nm / s, 5.0 nm /
In an optical disk on which a recording film is formed as s, the mixture ratio N ₂ / A at which the reflectivity in the groove is 11% or more is obtained.
r was 5%, 3%, 12%, and 30%, respectively. The results are plotted on the axis of abscissa, where the deposition rate is plotted, and on the axis of ordinate, the mixing ratio O ₂ /
When Ar is taken and shown in FIG. 28, a straight line β is obtained.

Then, the straight line β is expressed as Y = 5.5X + 2.7
It is represented by Here, the area above the straight line β is
This is a region where the groove reflectance is 11% or less and a sufficient signal modulation degree cannot be obtained.

When the film forming speed X is larger than 5.0 nm / s, it is difficult to adjust the film thickness because the film forming time is too fast, and when the film forming speed X is smaller than 0.1 nm / s, the film forming time X is smaller. It is unsuitable for production because it takes too much time. Therefore, it is preferable that the film forming speed X satisfies 0.1 ≦ X ≦ 5.0.

[0185] As can be seen from the above results, the present invention a phase change optical disc according to the, at the time of forming the recording film made of GeSbTe alloy, under an Ar gas atmosphere containing O ₂ gas, O ₂ The mixing ratio of the gas and the Ar gas is Y [%].
When the film forming speed of the recording film is X [nm / s],
By forming a film by sputtering under the conditions satisfying the following expressions (45) and (46), the GeSbTe alloy constituting the recording film 4 is suitably oxidized, and the recording / reproducing characteristics of the recording film 4 Is optimized. As a result, the phase-change optical disc 1 to which the present invention is applied can satisfy the conditions of the jitter value and the groove reflectivity of the reproduced signal, and the deterioration of the reproduced signal is suppressed as much as possible after repeated recording, and the repeated recording durability is improved. It was found that the recording performance was improved and good recording / reproducing characteristics were obtained even after repeated recording.

Y ≧ 2.3X + 1.0 (45) Y ≦ 5.5X + 2.7 (46) At this time, in the phase-change optical disc 1 to which the present invention is applied, recording is performed as described above. When the film forming speed X of the film 4 is 0.1
It is preferable that ≦ X ≦ 5.0.

Incidentally, in the recording film 4 used in the present invention, the composition ratio of Ge—Sb—Te constituting the recording film 4 is the ternary state of (Ge, Sb, Te) shown in FIG. In the figure, point J (26.0, 19.2, 54.
8), point K (21.0, 21.0, 58.0), point L
(14.3, 28.6, 57.1), point M (21.6,
24.4, 54.0).

[0188] 2. Composition of Phase Change Material Constituting Recording Film As described above, Ge-Sb-T constituting the recording film 4
The reason for defining the composition ratio of e is based on the following experimental results. Hereinafter, this experiment will be described in detail.

2-1 Ternary State of (Ge, Sb, Te)
In the figure, on a straight line connecting Ge ₅₀ Te ₅₀ and Sb ₄₀ Te ₆₀
Study of the composition First, the first dielectric film 3 made of ZnS-SiO ₂ having a thickness of 90nm on the substrate 2 was formed by sputtering.

[0190] Next, on the first dielectric film 3, the mixing ratio O ₂ / Ar between the O ₂ gas and Ar gas of 2.5% and the atmosphere, the deposition rate 0.42 nm / As s, a recording film 4 made of GeSbTe having a thickness of 25 nm was formed by sputtering.

At this time, when the recording film 4 is formed,
The target is formed by sputtering using a target composed of Ge ₂ Sb ₂ Te ₅ , a target composed of Ge, a target composed of Sb, and a target composed of Te.

Here, first, in the ternary phase diagram of (Ge, Sb, Te), as shown in FIG.
A phase change optical disk having a recording film having a composition on a straight line 11 connecting Ge ₅₀ Te ₅₀ and Sb ₄₀ Te ₆₀ was studied with emphasis on 2,5). Specifically, while maintaining the film formation rate ratio between the Ge target and the Te target at 1, Ge ₂ S
A recording film 4 having a composition between Ge ₅₀ Te ₅₀ and Ge ₂ Sb ₂ Te ₅ in FIG. 16 was formed by co-sputtering a b ₂ Te ₅ target.

Then, on this recording film 4, a film thickness of 15 nm
A second dielectric film 5 made of ZnS-SiO _2, thickness 1
A light reflecting film 6 of an Al alloy having a thickness of 50 nm was sequentially formed by sputtering, and thereafter, a protective film 7 was formed by applying an ultraviolet curable resin or the like on the light reflecting film 6 to obtain the phase change optical disk 1.

Finally, two phase-change optical disks are manufactured, and each of the light-reflecting films faces inward.
These phase change optical disks were adhered to each other via an adhesive to obtain a double-sided phase change optical disk having a diameter of 120 mm and a thickness of 1.2 mm.

In the same manner, a phase change optical disk in which only the composition of the recording film 4 was changed was manufactured. Specifically, by co-sputtering a Ge ₂ Sb ₂ Te ₅ target while maintaining the film formation rate ratio between the Ge target and the Te target at 0.67, Sb ₄₀ Te ₆₀ and Ge ₂ in FIG.
A recording film 4 having a composition between Sb ₂ Te ₅ was formed.

With respect to the phase-change optical disk having the recording film 4 having the composition represented by the point on the straight line 11 thus manufactured, the jitter value of the reproduced signal after 20,000 repetitive recordings was measured. The recording conditions at this time are as shown in FIG.
Under the same conditions as above, using the light emission pattern shown in FIG.
hz.

FIG. 29 shows the result. In FIG. 29, the abscissa indicates the ratio of Ge in the composition on the straight line 11 connecting Ge ₅₀ Te ₅₀ and Sb ₄₀ Te ₆₀ , and the ordinate indicates the jitter value of the reproduced signal. Note that points J, L, and C in FIG.
Point J (26.0, 19.2, 54.8), point L (14.3, 28.6, 57.1) and point C (2, 2, 2) in FIG.
5).

From the results shown in FIG. 29, (Ge, Sb, Te)
J (26.0, 19.2, 5) in the ternary phase diagram of
In a composition having a higher Ge content than 4.8), the jitter value becomes 12.5% or more, and the point L (14.3, 28.
It was also found that the jitter value was 12.5% or more even in a composition having a lower Ge content than that of the composition described in US Pat. Therefore, it was found that the composition on the straight line 11 connecting Ge ₅₀ Te ₅₀ and Sb ₄₀ Te ₆₀ is preferably a composition in a range connecting the point J and the point L as shown in FIG.

2-2 Ternary State of (Ge, Sb, Te)
In the figure, more Te is included than point C (2, 2, 5).
Examination of Composition Having Next, a phase change optical disc having a recording film having a composition containing more Te than point C (2, 2, 5) was examined. Specifically, a Ge ₂ Sb ₂ Te ₅ target and a Te ₂
By co-sputtering with a target, a phase-change optical disc having a recording film 4 having a composition on a straight line 12 from point C was produced.

With respect to the phase-change optical disk having the recording film 4 having the composition represented by the point on the straight line 12 thus manufactured, the jitter value of the reproduced signal after 20,000 times of recording was determined in the same manner as in FIG. It was measured.

FIG. 30 shows the result. In FIG. 30, the horizontal axis represents the proportion of Te in the composition on the straight line 12 connecting Ge ₂ Sb ₂ Te ₅ and Te, and the vertical axis represents the jitter value of the reproduced signal after 20,000 recordings. Note that points C and K in FIG. 30 correspond to points C (2, 2, 5) and K (2
1.0, 21.0, 58.0).

From the results shown in FIG. 30, as shown in FIG. 15, the point C is required for the jitter value to be 12.5% or less.
(2, 2, 5) and the point K (21.0, 21.0, 58.
0) was found to be preferable.

2-3 Ternary State of (Ge, Sb, Te)
In the figure, Sb is contained more than point C (2, 2, 5).
Examination of Composition Having Next, a phase change optical disc having a recording film having a composition containing a larger amount of Sb than point C (2, 2, 5) was examined. Specifically, a Ge ₂ Sb ₂ Te ₅ target and Sb
The point C is obtained by co-sputtering with the target.
A phase change optical disk having a recording film 4 having a composition on a straight line 13 was manufactured from the above.

With respect to the phase change optical disk having the recording film 4 having the composition represented by the point on the straight line 13 thus manufactured, the jitter value of the reproduced signal after 20,000 times of recording was measured in the same manner as in FIG. 29 described above. did.

FIG. 31 shows the result. In FIG. 31, the horizontal axis represents the ratio of Sb in the composition on the straight line 13 connecting Ge ₂ Sb ₂ Te ₅ and Sb, and the vertical axis represents the jitter value of the reproduced signal after 20,000 recordings. The points M and C in FIG. 31 correspond to the point M (21.6, 24.4, 5
4.0) and point C (2, 2, 5).

From the results shown in FIG. 31, as shown in FIG. 15, the point M (2
1.6, 24.4, 54.0) and point C were found to be preferable.

2-4 Preferred Set of Recording Film in the Present Invention
From the above results, the phase change optical disk 1 to which the present invention is applied
In the above, GeSbT of a recording film made of GeSbTe
e The composition ratio is point J (26.0, 19.2, 54.8),
Point K (21.0, 24.4, 58.0), point L (14.
3,28.6,57.1), point M (21.6,21.
6,54.0) was found to be preferable.

As described above, in the phase change optical disk 1 to which the present invention is applied, the recording / reproducing characteristics of the recording film 4 are further optimized by defining the composition of the phase change material constituting the recording film 4, The repetition durability is improved, and the deterioration of the reproduction signal is suppressed as much as possible even after many repetitive recordings, so that good recording / reproduction characteristics can be obtained.

Incidentally, the thickness of the recording film 4 in the present invention is preferably 18 nm to 30 nm. This is based on the following experimental results.

First, a 90 nm-thick ZnS—
A first dielectric film 3 made of SiO ₂ was formed.

Then, Ge is formed on the first dielectric film 3.
A recording film made of ₂ Sb ₂ Te _5, the deposition rate in an atmosphere mixing ratio O ₂ / Ar 2.5% and was the O ₂ gas and Ar gas as 0.42 nm / s, was formed by sputtering . At this time, the recording film is formed by changing the thickness of the recording film to 15 nm to 40 nm, and a plurality of substrates 2 having different thicknesses of the recording film are formed.
I got

Next, a second dielectric film made of ZnS-SiO _{2 having} a thickness of 15 nm and a light reflection film made of an Al alloy having a thickness of 150 nm are sequentially formed on the recording films 4 having different thicknesses by sputtering. To obtain a phase-change optical disk.

After initializing a plurality of phase change optical discs having different thicknesses of the recording films obtained as described above, a random EFM signal is repeatedly recorded using a light emission pattern as shown in FIG. The jitter value of the reproduced signal was measured. At this time, the linear velocity was 4.8 m / s, and the recording power Ph, the erasing power Pl, and the cooling power Pc were
The power was set so as to minimize the jitter of the reproduced signal after one recording.

As a result of such an experiment, it was found that the recording power of the phase change optical disk with a recording film thickness of less than 18 nm was 1
When a laser beam having a high power of 5 mW is used, there is a disadvantage that recording cannot be performed repeatedly. On the other hand, in the case of a phase change optical disk having a recording film thickness of more than 30 nm, the jitter value of the reproduced signal after recording 20,000 times becomes 12.5% or more, and there is a problem in repetition durability. Therefore, the thickness of the recording film 4 is 18 nm to 30 n.
It can be said that m is preferable.

The phase change optical disk 1 configured as described above is manufactured, for example, as follows.

First, the substrate 2 on which a predetermined pre-groove is formed by injection molding is manufactured. Then, a first dielectric film 3 is formed on the substrate 2 by an RF sputtering method.

Here, in the phase-change optical disc 1 according to the present embodiment, the thickness of the first dielectric film 3 is 70 nm to 1 nm.
It is preferably 30 nm. If the thickness of the first dielectric film is smaller than 70 nm, the groove reflectivity becomes low, and a sufficient reproduction signal cannot be obtained. On the other hand, in the case of a phase change optical disk in which the thickness of the first dielectric film is larger than 130 nm, the jitter value of the reproduced signal after 20,000 repetitive recordings becomes 12.5% or more, and the repetition durability is insufficient. Therefore, the thickness of the first dielectric film 3 is set to 70 nm.
By setting the thickness to 130 nm, a sufficient reproduction signal can be obtained, and sufficient repetition durability can be imparted.

Next, the recording film 4 is placed on the first dielectric
It is formed by the C sputtering method. In this case, in particular, in the method for manufacturing an optical recording medium according to the present invention, by using a GeSbTe alloy as a phase change material, and shall be performed in an Ar gas atmosphere containing O ₂ gas, the O ₂ gas and Ar
Assuming that the mixing ratio O ₂ / Ar with the gas is Y [%] and the film forming rate is X [nm / s], the following equations (47) and (4)
8)

Y ≧ 2.3X + 1.0 (47) Y ≦ 5.5X + 2.7 (48) As described above, according to the method of manufacturing an optical recording medium to which the present invention is applied, the recording film By defining the film-forming conditions of No. 4, the GeSbTe alloy constituting the recording film 4 is suitably oxidized, and the physical properties of the recording film 4 are optimized for repetitive recording. As a result, it is possible to provide an optical recording medium in which the deterioration of the reproduction signal is suppressed as much as possible even if the recording is repeated many times, and good recording and reproduction characteristics can be obtained.

Here, the deposition rate X is 0.1 nm
/ S or more and 5.0 nm / s or less.
As described above, according to the method for manufacturing an optical recording medium according to the present invention, the recording / reproducing characteristics of the recording film 4 are further optimized by setting the film forming speed within the above range, and the quality is improved even after repeated recording. It is possible to more effectively provide an optical recording medium having excellent recording / reproducing characteristics.

The composition of the recording film 4 thus formed is represented by a point J (26.0, 19.2, 54.8) in the ternary phase diagram of (Ge, Sb, Te). Point K (21.
0, 21.0, 58.0) and the point L (14.3, 28.
6,57.1) and the point M (21.6, 24.4, 54.
0) and GeSbT having a composition in a region surrounded by
e alloy.

By forming the recording film 4 having such a composition, the recording / reproducing characteristics of the recording film 4 are optimized, and an optical recording medium in which the deterioration of the reproduced signal is suppressed as much as possible after repeated recording is obtained.

Next, a second dielectric film 5 is formed on the recording film 4.
Is formed by an RF sputtering method. Then, a light reflection film 6 is formed on the second dielectric film 5 using an Al target.

Next, an ultraviolet curable resin is applied on the light reflecting film 6 by a spin coating method, and finally, the phase change optical disk 1 to which the present invention is applied is manufactured. In order to manufacture the double-sided phase-change optical disc 10 as shown in FIG. 2, for example, two phase-change optical discs 1 are produced, and these two phase-change optical discs are respectively attached to the respective light reflection films 6. Can be manufactured by bonding together via an adhesive so that they face each other inward.

<Third Embodiment> A phase-change optical disc according to the present embodiment is the same as the phase-change optical disc 1 shown in FIG.
Similarly, on the substrate 2, the first dielectric film 3, the recording film 4,
The second dielectric film 5, the light reflection film 6, and the protection film 7 are laminated in this order.

Here, the phase change optical disk according to the present embodiment is different only in the configuration of the recording film 4, and the constituent films other than the recording film 4 are the same as the substrate 2 and the first , The second dielectric film 5, the light reflecting film 6, and the protective film 7 have substantially the same configuration. Therefore, in the following description, the description of each of the constituent films will be omitted, and only the recording film 4 will be described.

The recording film 4 is made of a phase-change material that changes reversibly between a crystalline state and an amorphous state by irradiation with a light beam such as a laser beam. This is an optical recording layer on which information signals can be written, erased, and reproduced.

In particular, the phase change material of the recording film 4 in the present invention is a chalcogen compound made of a Ge—Sb—Te alloy. The recording film 4 has a thickness of 18 nm to 3 nm.
Preferably, it is 0 nm.

[0229] The recording film 4 in the present invention under an Ar gas atmosphere containing N ₂ gas, the mixing ratio N ₂ / Ar between the N ₂ gas and Ar gas as Y [%], the film formation rate To X
When [nm / s] is set, the film is formed by sputtering under the conditions satisfying the following expressions (49) and (50).

Y ≧ 1.8X + 5.0 (49) Y ≦ 12.8X + 16.7 (50) Further, the film formation rate X is 0.1 nm / s or more and 5.0.
It is preferably at most nm / s. That is, it is preferable that X satisfies the following expression (51).

[0231] 0.1 ≦ X ≦ 5 ··· (51 ) The above mixing ratio N ₂ / Ar is a flow ratio of N ₂ and Ar, in other words, the volume ratio of N ₂ and Ar in the atmosphere Is shown.

[0232] 1. Deposition speed X and atmosphere during recording film deposition
Examination of Ambient Conditions As described above, in the optical recording medium and the method of manufacturing the same according to the present invention, when forming the recording film 4, the mixing ratio Y [%] of N ₂ gas and Ar gas and Film speed X [nm
/ S] is defined as in the above equations (49), (50) and (51) based on the following experimental results. Hereinafter, this experiment will be described in detail.

1-1 Atmosphere Conditions During Recording Film Formation
Relationship between the signal characteristics of the reproduced signal is first to prepare a phase-change optical disk as follows.

First, the diameter is 120 mm and the thickness is 0.6 m
m substrate 2 was prepared. Then, a film having a thickness of 1
The first dielectric film 3 made of ZnS-SiO ₂ of 20nm
Was formed by sputtering.

Next, Ge _{2 is} deposited on the first dielectric film 3.
Using a target made of Sb ₂ Te ₅ , the film formation rate was set to 0.42 nm / s, and a 25 nm-thick Ge film was formed by sputtering in an Ar gas atmosphere mixed with N ₂ gas.
A recording film 4 made of -Sb-Te was formed by sputtering.

[0236] At this time, as an Ar gas atmosphere of a mixture of N ₂ gas, the mixing ratio N ₂ / Ar of the N ₂ gas and Ar gas 0
% In the range of 20% to 20%, and a plurality of recording films were formed under each condition. However, the mixing ratio N ₂ / Ar
Is 0%, which indicates an Ar gas atmosphere containing no N ₂ gas, and is not a recording film forming condition in the manufacturing method to which the present invention is applied.

Next, on the recording film 4 formed under each condition, a second dielectric film 5 made of ZnS-SiO ₂ having a thickness of 15 nm, and a light reflection film 6 made of an Al alloy having a thickness of 150 nm Were sequentially formed by sputtering, and a UV-curable resin was applied on the light reflecting film 6 to form a protective film 7, whereby the phase-change optical disc 1 was manufactured.

Then, two phase change optical disks 1 manufactured as described above are manufactured respectively, and the two phase change optical disks are bonded with an adhesive 9 so that the light reflection films 6 face each other inward. Specifically, a double-sided phase-change optical disc 10 capable of recording and reproducing from both sides as shown in FIG.
Was prepared. The double-sided phase change optical disk 10
Has a recording capacity of 3.0 GB per side. The track pitches of the phase change optical disks 1 and 10 are about 0.8 μm.

As described above, a plurality of phase-change optical disks manufactured by changing the film forming conditions were subjected to an initialization process for irradiating a strong laser beam to crystallize the recording film 4.

Then, for these phase-change optical disks after initialization, a random EFM signal is generated by using a light emission pattern as shown in FIG.
As recorded. Here, in FIG. 3, the recording power is Ph
, The erasing power Pl, and the cooling power Pc. In the light emission pattern in FIG. 3, one clock is 1T, and the pulse length of one light emission pulse is 13 ns.

At this time, the linear velocity is 4.8 m / s, the recording power Ph is 14.5 mW, the erasing power Pl is 5.8 mW, and the cooling power Pc is 1.5 m / s.
A recording / reproducing apparatus which is W was used. The recording / reproducing apparatus is equipped with a light source for generating a laser beam having a wavelength of 650 nm.

Under these conditions, recording was repeated twice on each phase-change optical disk.

In order to evaluate the relationship between the mixed gas condition of the N ₂ gas and the Ar gas at the time of forming the recording film and the signal characteristics of the reproduced signal, each phase-change optical disc after the recording was repeated twice. The jitter value of the reproduced signal after repeated recording was measured.

FIG. 32 shows the result. In FIG. 32, the abscissa indicates the mixture ratio N ₂ / Ar of N ₂ gas and Ar gas, and the ordinate indicates the jitter value of the reproduced signal when the same track is repeatedly recorded twice. Here, 10% is set as a media evaluation reference value as a jitter value at which a good reproduction signal is obtained.

In the above experiment, the jitter value after recording twice was measured, for the following reason. That is, usually, the jitter value after repeated recording is highest after recording twice, and tends to gradually decrease until it reaches 10,000 times of repeated recording. Therefore, here, the jitter value of the reproduced signal after the recording was repeated twice was measured.

[0246] As apparent from the results of FIG. 32, the jitter value, when the mixing ratio N ₂ / Ar is 0%, that is N ₂
12.7% when gas is not mixed in Ar gas
And decreases as the proportion of N ₂ gas increases, and becomes minimum when the mixture ratio N ₂ / Ar is 6% to 10%. When the mixing ratio N ₂ / Ar further increases, the jitter value gradually increases.

Therefore, as shown in FIG. 32, in order to set the jitter value of the reproduced signal after repeated recording to 10% or less, which is a value at which a good reproduction signal is normally obtained, the mixing ratio N
It has been found that it is desirable to form the recording film in an Ar gas atmosphere in which ₂ / Ar is 6% or more.

1-2 Atmosphere Conditions for Deposition of Recording Film and Each Data
The relationship between the groove reflectance of the disk then to evaluate the condition of the mixed gas atmosphere of N ₂ gas and Ar gas during recording film deposition, the relationship between the reflectance in the groove of the disk, as described above The reflectivity in the groove was measured for each phase-change optical disk after the recording film was formed and initialized while changing the atmosphere conditions at the time of forming the recording film.

FIG. 33 shows the result. In FIG. 33, the horizontal axis represents the mixture ratio N ₂ / Ar of the N ₂ gas and the Ar gas, and the vertical axis represents the reflectance in the groove.

As is apparent from the results shown in FIG. 33, the reflectance in the groove monotonously decreases as the mixing ratio N ₂ / Ar increases. Then, the mixing ratio N ₂ / Ar is 2
If it is 1% or more, the reflectivity in the groove becomes 11% or less, which causes a problem that a sufficient degree of modulation cannot be obtained.

Therefore, as shown in FIG. 33, in order to ensure a sufficient reproduction output, it was found that the mixing ratio N ₂ / Ar in the atmosphere at the time of forming the recording film was required to be 21% or less.

1-3 Both Signal Characteristics and Groove Reflectance
As described above, from the results shown in FIGS. 32 and 33, in the optical recording medium to which the present invention is applied and the method for manufacturing the same, the film formation rate of the recording film is 0.42 nm / s. In order to satisfy both the conditions of the jitter value of the reproduced signal and the reflectivity at the groove, it is necessary to form the recording film in an Ar gas atmosphere having a mixture ratio N ₂ / Ar of 6% to 21%. Turned out necessary.

The results of FIGS. 32 and 33 are as follows.
It is intended for an optical disc on which a recording film is formed at a film forming speed of 0.42 nm / s. Therefore, in order to obtain the same characteristics as those of the optical disks of FIGS. 32 and 33 when the film forming speed is changed, it is necessary to change the mixture ratio N ₂ / Ar of N ₂ gas and Ar gas.

1-4 Atmosphere in the case of changing the film forming speed
Relationship between ambient conditions and signal characteristics and groove reflectivity Then, when the film forming speed of the recording film is changed, the mixing ratio N that satisfies both the conditions of the jitter value of the reproduced signal and the reflectivity in the groove is satisfied. ₂ / Ar was studied.

Here, the voltage applied to the target made of Ge ₂ Sb ₂ Te ₅ was changed to set the film formation rate of the recording film to 0.1.
and nm / s, except that A recording film under conditions of changing the mixing ratio N ₂ / Ar of the N ₂ gas and Ar gas to 0% to 20%, as described above, double sided optical disc Was prepared, and the jitter value after recording twice repeatedly was measured in the same manner as in the experiment of FIG. FIG. 34 shows the result. Further, the film forming speed of the recording film is set to 0.1 nm / s,
The reflectivity of the groove after the initialization of the optical disk manufactured by changing the atmosphere conditions at the time of forming the recording film as described above was measured in the same manner as in the experiment of FIG. FIG. 35 shows the result.

Similarly, the film forming speed of the recording film was set to 1.6 n.
The phase change optical disk was manufactured by changing the atmosphere conditions at the time of forming the recording film as described above, and the jitter value of the reproduced signal after the recording was repeated twice and the reflectivity of the groove after the initialization were set to m / s. It was measured. Figure 3 shows the results
6 and FIG.

Similarly, a phase-change optical disk was manufactured at a recording film deposition rate of 5.0 nm / s, and the jitter value of the reproduced signal after the recording was repeated twice and the reflection of the groove after the initialization were performed. The rate was measured. The results are shown in FIGS. 38 and 39, respectively.

From the results shown in FIGS. 34, 36 and 38, the film formation rates were set to 0.1 nm / s, 1.6 nm / s,
In an optical disc on which a recording film is formed at 5.0 nm / s, the mixing ratio N ₂ / Ar at which the jitter value of the reproduction signal becomes 10% or less at which a good reproduction signal is obtained is 5% and 5%, respectively.
It turned out to be 8% and 14%.

From the results of FIG. 35, FIG. 37 and FIG. 39, the film formation rates were 0.1 nm / s, 1.6 nm / s,
In an optical disk on which a recording film is formed at a thickness of 5.0 nm / s, a mixture ratio N ₂ / A at which the groove reflectance becomes 11% or more is obtained.
r was found to be 17%, 40%, and 80%, respectively.

1-5 Both Signal Characteristics and Groove Reflectance
As discussed above recording film deposition conditions satisfying the square condition, Figure 32, Figure 34, from the results of FIGS. 36 and 38, the deposition rate 0.42 nm / s, 0.1 nm /
In an optical disk on which a recording film is formed at s, 1.6 nm / s, and 5.0 nm / s, the mixing ratio N ₂ / Ar at which the jitter value of the reproduced signal is 10% or less is 6% and 5%, respectively.
%, 8% and 14%. The results are shown in FIG. 40, with the abscissa plotting the film forming speed and the ordinate plotting the mixture ratio N ₂ / Ar, and the result is a straight line α.

In FIG. 40, the film formation rate on the horizontal axis is X [nm /
s], and the mixing ratio N ₂ / Ar on the vertical axis is Y [%].
Then, the straight line α is represented by Y = 1.8X + 5.0.
Here, the area below the straight line α is an area where the jitter value of the reproduction signal becomes 10% or more and a good reproduction signal cannot be obtained.

On the other hand, as described above, FIGS.
From the results of FIGS. 37 and 39, the deposition rate was set to 0.42 nm.
/ S, 0.1 nm / s, 1.6 nm / s, 5.0 nm /
In an optical disk on which a recording film is formed as s, the mixture ratio N ₂ / A at which the reflectivity in the groove is 11% or more is obtained.
r was 21%, 17%, 40%, and 80%, respectively. The results are shown in FIG. 40, where the abscissa indicates the film forming speed and the ordinate indicates the mixing ratio N ₂ / Ar.

Then, the straight line β is expressed as Y = 12.8X + 1
6.7. Here, the region above the straight line β is a region where the groove reflectance is 11% or less and a sufficient signal modulation degree cannot be obtained.

If the film forming speed X is larger than 5.0 nm / s, the film forming time is too long, and it is difficult to adjust the film thickness. If the film forming speed X is smaller than 0.1 nm / s, the film forming time X is smaller. It is unsuitable for production because it takes too much time. Therefore, it is preferable that the film forming speed X satisfies 0.1 ≦ X ≦ 5.0.

[0265] As can be seen from the above results, the present invention a phase change optical disc according to the, at the time of forming the recording film made of GeSbTe alloy, under an Ar gas atmosphere containing N ₂ gas, N ₂ The mixing ratio of the gas and the Ar gas is Y [%].
When the film forming speed of the recording film is X [nm / s],
By forming a film by sputtering under the conditions satisfying the following equations (52) and (53), the GeSbTe alloy constituting the recording film 4 is suitably nitrided, and the recording / reproducing characteristics of the recording film 4 Is optimized. As a result, the phase-change optical disc 1 to which the present invention is applied can satisfy the conditions of the jitter value and the groove reflectivity of the reproduction signal, and the deterioration of the reproduction signal is suppressed as much as possible after repeated recording, so that the phase change optical disk 1 is always stable. It has been found that recording and reproducing characteristics can be obtained.

Y ≧ 1.8X + 5.0 (52) Y ≦ 12.8X + 16.7 (53) At this time, in the phase change optical disc 1 to which the present invention is applied, recording is performed as described above. The film forming speed X of the film 4 is 0.1
It is preferable that ≦ X ≦ 5.0.

In the recording film 4 used in the present invention, the composition ratio of Ge—Sb—Te constituting the recording film 4 is the ternary state of (Ge, Sb, Te) shown in FIG. In the figure, point J (26.0, 19.2, 54.
8), point K (21.0, 21.0, 58.0), point L
(14.3, 28.6, 57.1), point M (21.6,
24.4, 54.0).

[0268] 2. Composition of Phase Change Material Constituting Recording Film As described above, Ge-Sb-T constituting the recording film 4
The reason for defining the composition ratio of e is based on the following experimental results. Hereinafter, this experiment will be described in detail.

2-1 Ternary State of (Ge, Sb, Te)
In the figure, on a straight line connecting Ge ₅₀ Te ₅₀ and Sb ₄₀ Te ₆₀
Study of the composition First, the first dielectric film 3 made of ZnS-SiO ₂ having a thickness of 120nm on the substrate 2 was formed by sputtering.

Next, on the first dielectric film 3, the film formation rate was set to 0.42 nm / s under an atmosphere in which the mixture ratio N ₂ / Ar of N ₂ gas and Ar gas was 10%. , Film thickness 2
A 5 nm GeSbTe recording film 4 was formed by sputtering.

At this time, when this recording film 4 is formed,
The target is formed by sputtering using a target composed of Ge ₂ Sb ₂ Te ₅ , a target composed of Ge, a target composed of Sb, and a target composed of Te.

Here, first, in the ternary phase diagram of (Ge, Sb, Te), as shown in FIG.
A phase change optical disk having a recording film having a composition on a straight line 11 connecting Ge ₅₀ Te ₅₀ and Sb ₄₀ Te ₆₀ was studied with emphasis on 2,5). Specifically, while maintaining the film formation rate ratio between the Ge target and the Te target at 1, Ge ₂ S
A recording film 4 having a composition between Ge ₅₀ Te ₅₀ and Ge ₂ Sb ₂ Te ₅ in FIG. 16 was formed by co-sputtering a b ₂ Te ₅ target.

Then, on this recording film 4, a film thickness of 15 nm
A second dielectric film 5 made of ZnS-SiO _2, thickness 1
A light reflecting film 6 of an Al alloy having a thickness of 50 nm was sequentially formed by sputtering, and thereafter, a protective film 7 was formed by applying an ultraviolet curable resin or the like on the light reflecting film 6 to obtain the phase change optical disk 1.

Finally, two phase change optical disks are manufactured, and each of the light reflection films faces inward.
These phase change optical disks were adhered to each other via an adhesive to obtain a double-sided phase change optical disk having a diameter of 120 mm and a thickness of 1.2 mm.

In the same manner, a phase change optical disk in which only the composition of the recording film 4 was changed was manufactured. Specifically, by co-sputtering a Ge ₂ Sb ₂ Te ₅ target while maintaining the film formation rate ratio between the Ge target and the Te target at 0.67, Sb ₄₀ Te ₆₀ and Ge ₂ in FIG.
A recording film 4 having a composition between Sb ₂ Te ₅ was formed.

With respect to the phase-change optical disk having the recording film 4 having the composition represented by the point on the straight line 11 thus manufactured, the jitter value of the reproduced signal after one-time recording was measured.
The recording conditions at this time are the same as those described above with reference to FIG. 32, using the light emission pattern shown in FIG.
The M signal was recorded.

FIG. 41 shows the result. In FIG. 41, the abscissa indicates the ratio of Ge in the composition on the straight line 11 connecting Ge ₅₀ Te ₅₀ and Sb ₄₀ Te ₆₀ , and the ordinate indicates the jitter value of the reproduced signal. Note that points J, L, and C in FIG.
Point J (26.0, 19.2, 54.8), point L (14.3, 28.6, 57.1) and point C (2, 2, 2) in FIG.
5).

From the result of FIG. 41, (Ge, Sb, Te)
J (26.0, 19.2, 5) in the ternary phase diagram of
In a composition having a Ge content higher than 4.8), the jitter value becomes 10% or more, and the point L (14.3, 28.6, 5) is obtained.
Even in a composition having a lower Ge content than 7.1),
It was found that the jitter value was 10% or more. Therefore, it was found that the composition on the straight line 11 connecting Ge ₅₀ Te ₅₀ and Sb ₄₀ Te ₆₀ is preferably a composition in a range connecting the point J and the point L as shown in FIG.

2-2 Ternary State of (Ge, Sb, Te)
In the figure, more Te is included than point C (2, 2, 5).
Examination of Composition Having Next, a phase change optical disc having a recording film having a composition containing more Te than point C (2, 2, 5) was examined. Specifically, a Ge ₂ Sb ₂ Te ₅ target and a Te ₂
By co-sputtering with a target, a phase-change optical disc having a recording film 4 having a composition on a straight line 12 from point C was produced.

With respect to the phase-change optical disc having the recording film 4 having the composition represented by the point on the straight line 12 manufactured in this manner, the jitter value of the reproduced signal after one-time recording is determined in the same manner as in FIG. It was measured.

FIG. 42 shows the result. In FIG. 42, the horizontal axis represents the proportion of Te in the composition on the straight line 12 connecting Ge ₂ Sb ₂ Te ₅ and Te, and the vertical axis represents the jitter value of the reproduced signal. The points C and K in FIG. 42 correspond to the points C (2, 2, 5) and K (21.0, 21.0, 5) in FIG.
8.0).

From the result of FIG. 42, as shown in FIG. 15, the point C (2, 2, 5) and the point K (21.0, 21.0,
58.0) was found to be preferable.

2-3 Ternary State of (Ge, Sb, Te)
In the figure, Sb is contained more than point C (2, 2, 5).
Examination of Composition Having Next, a phase change optical disc having a recording film having a composition containing a larger amount of Sb than point C (2, 2, 5) was examined. Specifically, a Ge ₂ Sb ₂ Te ₅ target and Sb
The point C is obtained by co-sputtering with the target.
A phase change optical disk having a recording film 4 having a composition on a straight line 13 was manufactured from the above.

With respect to the phase-change optical disc having the recording film 4 having the composition represented by the point on the straight line 13 thus manufactured, the jitter value of the reproduced signal after one-time recording was measured in the same manner as in FIG. did. The result is shown in FIG. FIG.
In FIG. 3, the horizontal axis represents a straight line 13 connecting Ge ₂ Sb ₂ Te ₅ and Sb.
The ratio of Sb in the above composition was taken, and the vertical axis represents the jitter value of the reproduced signal. Note that points M and C in FIG.
These correspond to points M (21.6, 24.4, 54.0) and points C (2, 2, 5) in FIG.

From the results of FIG. 43, as shown in FIG. 15, the point M (21.6, 24.4, 54.0) and the point C
It has been found that a composition in the range connecting (2, 2, 5) is preferable.

2-4 Preferred Set of Recording Film in the Present Invention
From the above results, the phase change optical disk 1 to which the present invention is applied
In FIG. 15, as shown in FIG. 15, the GeSbTe composition ratio of the GeSbTe recording film is changed to the point J (26.0,
19.2, 54.8), point K (21.0, 21.0, 5)
8.0), a composition within a region surrounded by a point L (14.3, 28.6, 57.1), and a point M (21.6, 24.4, 54.0). did.

As described above, in the phase change optical disc 1 to which the present invention is applied, the recording / reproducing characteristics of the recording film 4 are optimized and the recording / reproducing characteristics of the recording film 4 are improved after the recording is performed. In this case, the jitter value of the reproduction signal is suppressed as much as possible, and the deterioration of the reproduction signal is suppressed. As a result, the phase change optical disc 1 to which the present invention is applied can always obtain stable recording and reproduction characteristics even after repeated recording.

By the way, the thickness of the recording film 4 in the present invention is preferably 18 nm to 30 nm. This is based on the following experimental results.

First, a 120 nm-thick ZnS
Forming a first dielectric film 3 made of -SiO _2.

Then, Ge is formed on the first dielectric film 3.
_A recording film made of ₂ Sb ₂ Te ₅ was formed by sputtering at a film formation rate of 0.42 nm / s in an atmosphere in which the mixture ratio N ₂ / Ar of N ₂ gas and Ar gas was 10%. At this time, the recording film was formed by changing the thickness of the recording film to 15 nm to 40 nm, and a plurality of substrates 2 having different thicknesses of the recording film were obtained.

Next, a second dielectric film made of ZnS-SiO _{2 having} a thickness of 15 nm and a light reflection film made of an Al alloy having a thickness of 150 nm are sequentially formed on the recording films 4 having different thicknesses by sputtering. Then, a protective film made of an ultraviolet curable resin was formed on the light reflecting film to obtain a phase change optical disk.

After initializing a plurality of phase change optical discs having different thicknesses of the recording films thus obtained, a random EFM signal is recorded and reproduced by using a light emission pattern as shown in FIG. The jitter value of the signal was measured. At this time, the linear velocity was set to 4.8 m / s, and the recording power Ph, the erasing power Pl, and the cooling power Pc were set to such a power as to minimize the jitter of the reproduced signal after one recording.

From these results, it is found that a phase change optical disk having a recording film thickness of less than 18 nm has a deteriorated film quality, and cannot be repeatedly recorded when a high power laser beam having a recording power Ph of 15 mW is used. I understood that. Further, the thickness of the recording film is 30 nm.
With a larger phase change optical disk, the jitter value of the reproduced signal after recording 10,000 times was 12.5% or more, which caused a problem in repeated durability. Therefore, it can be said that the thickness of the recording film 4 is preferably 18 nm to 30 nm.

The phase change optical disk 1 configured as described above is manufactured, for example, as follows.

First, a substrate 2 made of polycarbonate having a predetermined pregroove formed by injection molding is manufactured. Then, on the substrate 2, a first dielectric film 3 made of ZnS-SiO ₂ is formed by RF sputtering.

Next, a recording film 4 is formed on the first dielectric film 3 by a DC sputtering method. In this case, in particular, in the method for manufacturing an optical recording medium according to the present invention, by using a GeSbTe alloy as a phase change material, and shall be performed in an Ar gas atmosphere containing N ₂ gas, the N ₂ gas and A
Assuming that the mixing ratio N ₂ / Ar with r gas is Y [%] and the film forming rate is X [nm / s], the following equations (54) and (5)
5) Be satisfied.

Y ≧ 1.8X + 5.0 (54) Y ≦ 12.8X + 16.7 (55) As described above, according to the method of manufacturing an optical recording medium to which the present invention is applied, the recording film By controlling the film forming conditions of No. 4, the GeSbTe alloy constituting the recording film 4 is suitably nitrided, and the recording / reproducing characteristics of the recording film 4 are optimized. As a result, according to the method for manufacturing an optical recording medium to which the present invention is applied, deterioration of a reproduction signal is suppressed as much as possible even after repeated recording, so that an optical recording medium that always obtains stable recording and reproduction characteristics and has high reliability is obtained. A medium can be provided.

Here, the film forming speed X is 0.1 nm
/ S or more and 5.0 nm / s or less.
As described above, according to the method of manufacturing an optical recording medium according to the present invention, the recording / reproducing characteristics of the recording film 4 are further optimized by setting the film forming speed to the above range, and the recording / reproducing characteristics are always maintained even after repeated recording. It is possible to provide an optical recording medium capable of obtaining stable recording / reproducing characteristics.

The composition of the recording film 4 thus formed is represented by a point J (26.0, 19.2, 54.8) in the ternary phase diagram of (Ge, Sb, Te). Point K (21.
0, 21.0, 58.0) and the point L (14.3, 28.
6,57.1) and the point M (21.6, 24.4, 54.
0) and GeSbT having a composition in a region surrounded by
e alloy.

By forming the recording film 4 having such a composition, the recording / reproducing characteristics of the recording film 4 are optimized, and an optical recording medium in which the deterioration of the reproduced signal is suppressed as much as possible even after repeated recording is obtained. .

Next, on this recording film 4, ZnS-SiO
_{A second} dielectric film 5 of 2 is formed by RF sputtering. Then, a light reflection film 6 is formed on the second dielectric film 5 using an Al target.

Next, an ultraviolet curable resin is applied and formed on the light reflecting film 6 by a spin coating method, and finally, the phase change optical disk 1 to which the present invention is applied is manufactured. In addition,
In order to manufacture the double-sided phase-change optical disc 10 as shown in FIG. 2, for example, two phase-change optical discs 1 are produced, and these two phase-change optical discs are connected to each other by the respective light reflection films 6. It is manufactured by pasting through an adhesive so as to face the inside.

[0303]

EXAMPLES Next, the following experiments were conducted to evaluate the effects of the method of manufacturing an optical recording medium to which the present invention was applied.

First Experimental Example In this experimental example, when forming a recording film, N ₂ gas and O ₂ gas were used.
The effect of using Ar gas containing gas as a sputtering gas was examined.

[0305] <Example> First, a polycarbonate substrate on which grooves are formed along the recording track, forming a first dielectric film made of ZnS-SiO ₂ having a thickness of 120nm on the substrate did.

Next, on the first dielectric film, a mixture ratio of N ₂ gas and O ₂ gas to Ar gas (N ₂ + O ₂ ) / A
The r and 10%, the ratio O ₂ / a O ₂ gas occupying the N ₂ gas and O ₂ gas (N ₂ + O ₂₎ in an atmosphere was 20%
The deposition rate is 0.42 nm / s,
A recording film made of e ₂ Sb ₂ Te ₅ was formed.

Then, a 15 nm-thick Z was deposited on this recording film.
Second dielectric film made of nS—SiO ₂ , thickness 150 n
A light reflecting film made of Al alloy was formed by sputtering in order. Then, an ultraviolet curing resin was applied on the light reflecting film by spin coating to form a protective film having a thickness of 10 μm, thereby obtaining a phase change optical disk.

<Comparative Example> On the other hand, when forming a recording film, N
Ar consisting only of Ar gas without introducing ₂ gas and O ₂ gas
A phase-change optical disk was obtained in the same manner as in the above example, except that the recording film was formed in an atmosphere.

The phase change optical disks obtained in the above Examples and Comparative Examples are respectively initialized, and thereafter, random EFM signals are repeatedly recorded on these phase change optical disks using the light emission pattern of FIG. Jitter values were measured.

The results of the example are shown in FIG. 44, and the results of the comparative example are shown in FIG.

As is clear from the results shown in FIG. 44, the second embodiment of the present invention in which the recording film was formed in an Ar atmosphere containing a predetermined ratio of N ₂ gas and O ₂ gas was applied. No increase in the jitter value after recording was observed.
The jitter value is stable at 12.5% or less up to 100,000 times.

On the other hand, as is apparent from the results of FIG.
In the comparative example in which the recording film was formed in an Ar atmosphere containing neither N ₂ gas nor O ₂ gas, the jitter value was locally increased after the second to tenth recordings, and the number of repetitive recordings was When the number of times exceeds 10,000, the jitter value sharply increases.

From the above results, by forming a recording film at a predetermined film forming rate in an Ar atmosphere containing a predetermined amount of N ₂ gas and O ₂ gas, a small number of times such as several times can be obtained. It has been found that the local increase in the jitter of the reproduced signal observed after repeated recording is suppressed as much as possible, and the sudden increase in the jitter of the reproduced signal observed after repeated recording such as tens of thousands of times is suppressed as much as possible.

Second Experimental Example In this experimental example, the effect of using an Ar gas containing an O ₂ gas as a sputtering gas when forming a recording film was examined.

<Example> A 90 nm-thick ZnS film was formed on a substrate.
After forming a first dielectric film made of —SiO ₂ , a film formation rate of 0.42 nm / s is set on the first dielectric film under an atmosphere with a mixing ratio of O ₂ / Ar of 10%. Film pressure 25
A recording film made of Ge ₂ Sb ₂ Te ₅ nm was formed. Then, a 15 nm-thick ZnS—SiO ₂ film is formed on this recording film.
A second dielectric film made of and a light reflecting film made of an Al alloy having a film thickness of 150 nm were sequentially formed by sputtering.
Thereafter, a UV-curable resin was applied on the light reflecting film to form a protective film having a thickness of 10 nm, thereby obtaining a phase change optical disk.

<Comparative Example> On the other hand, when a recording film was formed,
_A phase change optical disk was obtained in the same manner as in the above example, except that the recording film was formed in an Ar atmosphere consisting of only Ar gas without introducing ₂ .

The phase change optical disks obtained in the above Examples and Comparative Examples are respectively initialized, and thereafter, random EFM signals are repeatedly recorded on these phase change optical disks using the light emission pattern of FIG. Then, the jitter value of the reproduced signal was measured. The results are shown in FIGS.
7 respectively.

As is clear from the results shown in FIG. 46, in the embodiment to which the present invention was applied in which the recording film was formed in an Ar atmosphere containing a predetermined ratio of O ₂ gas, the repeated recording was performed. The increase in the jitter value of the reproduction signal is small, and the jitter value of the reproduction signal is 10% up to 100,000 times of repeated recording.
As shown below, stable recording / reproducing characteristics are obtained.

On the other hand, as is clear from the results of FIG.
In the comparative example in which the recording film was formed in an Ar atmosphere containing no O ₂ gas, the jitter value sharply increased when the number of repetitive recordings was 20,000.

From the above results, by forming a recording film at a predetermined film formation rate in an Ar atmosphere containing a predetermined range of O ₂ gas, a good reproduction signal can be obtained even if recording is repeated many times. It has been found that an optical recording medium can be provided.

Third Experimental Example In this experimental example, the effect of using an Ar gas containing N ₂ gas as a sputtering gas when forming a recording film was examined.

<Example> A 120-nm thick Zn film was formed on a substrate.
After forming a first dielectric film made of S-SiO ₂ , a film formation rate of 0.42 nm / s is set on this first dielectric film under an atmosphere with a mixture ratio N ₂ / Ar of 10%. As film thickness 2
A recording film made of Ge ₂ Sb ₂ Te ₅ having a thickness of ₅ nm was formed.
Then, on this recording film, a ZnS-SiO film having a thickness of 15 nm is formed.
_{A second} dielectric film made of No. 2 and a light reflecting film made of an Al alloy having a thickness of 150 nm were sequentially formed by sputtering. Thereafter, a UV-curable resin was applied on the light reflecting film to form a protective film having a thickness of 10 nm, thereby obtaining a phase change optical disk.

<Comparative Example> On the other hand, as a comparative example, an Ar gas consisting of only Ar gas without introducing N ₂ when forming a recording film was used.
A phase-change optical disk was obtained in the same manner as in the above example, except that the recording film was formed in an atmosphere.

The phase change optical disks obtained in the above Examples and Comparative Examples were initialized, and thereafter, random EFM signals were repeatedly recorded and reproduced on these phase change optical disks using the light emission pattern of FIG. Was measured. The results are shown in FIGS. 48 and 49, respectively.

As is clear from the results shown in FIG. 48, the phase change optical disk to which the present invention is applied in which the recording film is formed in an Ar atmosphere containing a predetermined ratio of N ₂ gas has a second repetition of recording. Thereafter, no increase in the jitter value was observed, and the jitter value of the reproduced signal was stable at 8% or less until the number of repetitive recordings reached 10,000.

On the other hand, as is apparent from the results of FIG.
The phase change optical disc of the comparative example in which the recording film was formed in an Ar atmosphere containing no N ₂ gas had a repetitive recording count of 2
The jitter value after the first time sharply increases, and recording must be repeated about 100 times until the jitter value of the reproduced signal is stabilized to 10% or less.

From the above results, by forming a recording film in an Ar atmosphere containing a predetermined range of N ₂ gas, it is possible to obtain an optical recording medium that can obtain a good reproduction signal even if it is repeatedly recorded many times. Turned out to be able to provide.

[0328]

As described above, in the optical recording medium according to the present invention, since the conditions for forming the recording film are defined, the GeSbTe alloy constituting the recording film is suitably nitrided and oxidized, and the recording film is formed. Are optimized with respect to the recording / reproducing characteristics, and the repetitive recording durability is further improved. Therefore, in the optical recording medium according to the present invention, the local degradation phenomenon of the reproduction signal seen after performing the recording several to several tens of times is minimized, and even if the recording is repeated several tens of thousands or more, it is satisfactory. As a result, stable and good recording / reproducing characteristics can always be obtained even after repeated recording, and high reliability can be obtained.

In the method for manufacturing an optical recording medium according to the present invention, since the conditions for forming the recording film are defined, the GeSbTe alloy forming the recording film is suitably nitrided and oxidized, and the physical properties of the recording film are reduced. The recording / reproducing characteristics are optimized, and the repetitive recording durability is further improved. This allows
According to the method for manufacturing an optical recording medium according to the present invention, the local deterioration phenomenon of the reproduction signal seen after performing the repetitive recording several to several tens of times is minimized, and the repetitive recording is performed tens of thousands of times or more. Thus, a good reproduction signal can be obtained, and as a result, a highly reliable optical recording medium having stable and good recording and reproduction characteristics always after repeated recording can be provided.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing a main part of an example of a phase change optical disk to which the present invention is applied.

FIG. 2 is an enlarged sectional view showing a main part of another example of the phase change optical disk to which the present invention is applied.

FIG. 3 is a diagram showing a light emission pattern used when an information signal is recorded in an experiment.

FIG. 4 shows a mixture ratio (N ₂ + O ₂ ) / in a film formation atmosphere when a film formation speed of a recording film is 0.42 nm / s.
FIG. 4 is a diagram illustrating a relationship between Ar and a jitter value of a reproduction signal.

FIG. 5 shows a mixture ratio (N ₂ + O ₂ ) / in a film formation atmosphere when a film formation speed of a recording film is 0.42 nm / s.
FIG. 4 is a diagram illustrating a relationship between Ar and the reflectance in a groove.

FIG. 6 shows a mixture ratio (N ₂ + O ₂ ) / A in a film formation atmosphere when a film formation speed of a recording film is set to 0.1 nm / s.
FIG. 6 is a diagram illustrating a relationship between r and a jitter value of a reproduction signal.

FIG. 7 shows a mixing ratio (N ₂ + O ₂ ) / A in a film formation atmosphere when the film formation speed of a recording film is 0.1 nm / s.
FIG. 4 is a diagram illustrating a relationship between r and the reflectance in a groove.

FIG. 8 shows a mixture ratio (N ₂ + O ₂ ) / A in a film formation atmosphere when a film formation speed of a recording film is 1.6 nm / s.
FIG. 6 is a diagram illustrating a relationship between r and a jitter value of a reproduction signal.

FIG. 9 shows a mixing ratio (N ₂ + O ₂ ) / A in a film formation atmosphere when the film formation speed of a recording film is 1.6 nm / s.
FIG. 4 is a diagram illustrating a relationship between r and the reflectance in a groove.

FIG. 10 shows a mixture ratio (N ₂ + O ₂ ) / in a film formation atmosphere when the film formation speed of a recording film is 5.0 nm / s.
FIG. 4 is a diagram illustrating a relationship between Ar and a jitter value of a reproduction signal.

FIG. 11 shows a mixture ratio (N ₂ + O ₂ ) / in a film formation atmosphere when the film formation speed of a recording film is 5.0 nm / s.
FIG. 4 is a diagram illustrating a relationship between Ar and the reflectance in a groove.

FIG. 12 is a diagram illustrating a relationship between a film forming speed of a recording film and a mixing ratio (N ₂ + O ₂ ) / Ar in a film forming atmosphere.

FIG. 13 shows a mixture ratio O ₂ / (N ₂ +
FIG. 9 is a diagram showing a relationship between O ₂ ) and a jitter value of a reproduced signal.

FIG. 14 shows a mixture ratio O ₂ / (N ₂ +
FIG. 4 is a diagram showing a relationship between O ₂ ) and a recording power margin.

FIG. 15 is a view showing a composition of a constituent material of a recording film in the present invention.

FIG. 16 shows Ge, which is a constituent material of a recording film according to the present invention.
FIG. 3 is a ternary phase diagram of SbTe.

FIG. 17 shows G in the material of the recording film GeSbTe.
FIG. 6 is a diagram illustrating a relationship between an e content rate and a jitter value of a reproduced signal.

FIG. 18 is a graph showing the relation between T in the constituent material GeSbTe of the recording film.
FIG. 6 is a diagram illustrating a relationship between an e content rate and a jitter value of a reproduced signal.

FIG. 19: S in GeSbTe, a constituent material of a recording film
FIG. 4 is a diagram illustrating a relationship between a b content rate and a jitter value of a reproduced signal.

FIG. 20 is a diagram showing a relationship between a mixing ratio O ₂ / Ar and a jitter value in a film formation atmosphere when a film formation speed of a recording film is 0.42 nm / s.

FIG. 21 is a diagram showing the relationship between the mixture ratio O ₂ / Ar in the film formation atmosphere and the reflectance in the groove when the film formation speed of the recording film is 0.42 nm / s.

FIG. 22 is a diagram illustrating a relationship between a mixing ratio O ₂ / Ar and a jitter value in a film formation atmosphere when a film formation speed of a recording film is set to 0.1 nm / s.

FIG. 23 is a diagram showing the relationship between the mixture ratio O ₂ / Ar in the film formation atmosphere and the reflectance in the groove when the film formation speed of the recording film is 0.1 nm / s.

FIG. 24 is a diagram showing the relationship between the mixing ratio O ₂ / Ar and the jitter value in the film formation atmosphere when the film formation speed of the recording film is 1.6 nm / s.

FIG. 25 is a diagram showing the relationship between the mixture ratio O ₂ / Ar in the film formation atmosphere and the reflectivity in the groove when the film formation speed of the recording film is 1.6 nm / s.

FIG. 26 is a diagram showing a relationship between a mixing ratio O ₂ / Ar and a jitter value in a film formation atmosphere when a film formation speed of a recording film is 5.0 nm / s.

FIG. 27 is a diagram showing the relationship between the mixture ratio O ₂ / Ar in the film formation atmosphere and the reflectance in the groove when the film formation speed of the recording film is 5.0 nm / s.

FIG. 28 is a diagram showing a relationship between a film forming speed of a recording film and a mixing ratio O ₂ / Ar in a film forming atmosphere.

FIG. 29 shows G in the material GeSbTe of the recording film.
FIG. 6 is a diagram illustrating a relationship between an e content rate and a jitter value of a reproduced signal.

FIG. 30 shows T in the material of the recording film GeSbTe.
FIG. 6 is a diagram illustrating a relationship between an e content rate and a jitter value of a reproduced signal.

FIG. 31 shows S in GeSbTe, a constituent material of a recording film.
FIG. 4 is a diagram illustrating a relationship between a b content rate and a jitter value of a reproduced signal.

FIG. 32 is a diagram showing a relationship between a mixture ratio N ₂ / Ar and a jitter value in a film formation atmosphere when a film formation speed of a recording film is 0.42 nm / s.

FIG. 33 is a diagram showing the relationship between the mixture ratio N ₂ / Ar in the film formation atmosphere and the reflectivity in the groove when the film formation speed of the recording film is 0.42 nm / s.

FIG. 34 is a diagram showing a relationship between a mixing ratio N ₂ / Ar and a jitter value in a film formation atmosphere when a film formation speed of a recording film is set to 0.1 nm / s.

FIG. 35 is a diagram showing the relationship between the mixture ratio N ₂ / Ar in the film formation atmosphere and the reflectance in the groove when the film formation speed of the recording film is 0.1 nm / s.

FIG. 36 is a diagram showing a relationship between a mixture ratio N ₂ / Ar and a jitter value in a film formation atmosphere when a film formation speed of a recording film is 1.6 nm / s.

FIG. 37 is a diagram showing the relationship between the mixture ratio N ₂ / Ar in the film formation atmosphere and the reflectance in the groove when the film formation speed of the recording film is 1.6 nm / s.

FIG. 38 is a diagram showing the relationship between the mixture ratio N ₂ / Ar and the jitter value in the film formation atmosphere when the film formation speed of the recording film is 5.0 nm / s.

FIG. 39 is a diagram showing the relationship between the mixture ratio N ₂ / Ar in the film formation atmosphere and the reflectivity in the groove when the film formation speed of the recording film is 5.0 nm / s.

FIG. 40 is a diagram showing a relationship between a film forming speed of a recording film and a mixture ratio N2 / Ar in a film forming atmosphere.

FIG. 41 shows G in the constituent material GeSbTe of the recording film.
FIG. 6 is a diagram illustrating a relationship between an e content rate and a jitter value of a reproduced signal.

FIG. 42 shows T in GeSbTe, a constituent material of a recording film.
FIG. 6 is a diagram illustrating a relationship between an e content rate and a jitter value of a reproduced signal.

FIG. 43: S in GeSbTe, a constituent material of a recording film
FIG. 4 is a diagram illustrating a relationship between a b content rate and a jitter value of a reproduced signal.

FIG. 44 is a diagram showing a relationship between the number of repetitive recordings and the jitter value of a reproduction signal in the phase change optical disk of the example in the first experimental example.

FIG. 45 is a diagram showing the relationship between the number of repetitive recordings and the jitter value of a reproduction signal in the phase change optical disk of the comparative example in the first experimental example.

FIG. 46 is a diagram showing, in a second experimental example, a relationship between the number of repetitive recordings and the jitter value of a reproduction signal in the phase change optical disc of the example.

FIG. 47 is a diagram showing, in a second experimental example, a relationship between the number of repetitive recordings and a jitter value of a reproduction signal in a phase change optical disk of a comparative example.

FIG. 48 is a diagram illustrating a relationship between the number of repetitive recordings and the jitter value of a reproduction signal in the phase change optical disc of the example in the third experimental example.

FIG. 49 is a diagram illustrating, in a third experimental example, a relationship between the number of repetitive recordings and a jitter value of a reproduction signal in the phase change optical disc of the comparative example.

[Explanation of symbols]

1 phase change optical disk, 2 substrate, 3 first dielectric film, 4 recording film, 5 second dielectric film, 6 light reflection film, 7 protective film

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Yoshihiro Saito, Inventor 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Noriko Kikuchi Inventor 6-35, 7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (29)

[Claims] An information signal is recorded by irradiating a light beam to cause a phase change in said recording film, comprising a recording film made of a phase change material in which a phase change between a crystalline state and an amorphous state occurs. In the optical recording medium, the phase change material contains a GeSbTe alloy, and the recording film is formed by sputtering in an Ar gas atmosphere containing at least one of N ₂ gas and O ₂ gas. An optical recording medium characterized by the above-mentioned. Wherein said recording film is made is deposited in Ar gas atmosphere containing N ₂ gas and O ₂ gas, the mixing ratio of N ₂ gas and O ₂ gas to the Ar gas (N ₂ + O ₂ ) / A
r is Y [%], and O occupies in the N ₂ gas and O ₂ gas.
_When the ratio O ₂ / (N ₂ + O ₂ ) of the _two gases is Z [%] and the deposition rate is X [nm / s], X, Y and Z are represented by the following formulas (1) and (2). 2. The optical recording medium according to claim 1, wherein the optical recording medium satisfies (3) and (3). Y ≧ 2.3X + 1.0 (1) Y ≦ 12.8X + 16.7 (2) 10 ≦ Z ≦ 60 (3) 3. The film forming speed X is 0.1 [nm / s].
3. The optical recording medium according to claim 2, wherein said optical recording medium is 5.0 [nm / s] or less. 4. GeSbT contained in the phase change material
The e alloy has a point (26.0, 19.2, 54.8) and a point (2) in the ternary phase diagram of (Ge, Sb, Te).
1.0, 21.0, 58.0) and a point (14.3, 2
8.6, 57.1) and points (21.6, 24.4, 5)
3. The optical recording medium according to claim 2, wherein the composition is a composition in a region surrounded by 4.0). 5. The recording film having a thickness of 18 nm to 30 nm.
The optical recording medium according to claim 2, wherein: 6. The recording film is formed on a substrate. The substrate has a diameter of 120 ± 0.3 mm, a thickness of 0.60 ± 0.03 mm, and a track pitch of 0.8. 3. The optical recording medium according to claim 2, wherein the thickness is ± 0.01 μm. 7. The recording film according to claim 1, wherein the recording film is made of Ar containing O ₂ gas.
It is deposited in a gas atmosphere, the mixing ratio O ₂ / Ar between the O ₂ gas and the Ar gas was Y [%], when the film formation rate and X [nm / s], X and 2. Y satisfies the following formulas (4) and (5).
The optical recording medium according to the above. Y ≧ 2.3X + 1.0 (4) Y ≦ 5.5X + 2.7 (5) 8. The film forming speed X is 0.1 [nm / s].
8. The optical recording medium according to claim 7, wherein said optical recording medium is 5.0 [nm / s] or less. 9. The phase change material made of the GeSbTe alloy includes a point (26.0, 19.2, 54.8) and a point (21.0) in a ternary phase diagram of (Ge, Sb, Te). ,
21.0, 58.0) and points (14.3, 28.6, 5)
8. The optical recording medium according to claim 7, wherein the composition is in a region surrounded by 7.1) and a point (21.6, 24.4, 54.0). 10. The recording film has a thickness of 18 nm to 30 n.
The optical recording medium according to claim 7, wherein m is m. 11. The recording film is formed on a substrate. The substrate has a diameter of 120 ± 0.3 mm, a thickness of 0.60 ± 0.03 mm, and a track pitch of 0.8. 8. The optical recording medium according to claim 7, wherein the distance is ± 0.01 μm. 12. The recording film according to claim 1, wherein said recording film contains N ₂ gas.
The film was formed under an atmosphere of r gas, the mixture ratio N ₂ / Ar of N ₂ gas and Ar gas was set to Y [%], and the film formation rate was set to X
The optical recording medium according to claim 1, wherein when [nm / s], X and Y satisfy the following Expressions (6) and (7). Y ≧ 1.8X + 5.0 (6) Y ≦ 12.8X + 16.7 (7) 13. The film formation rate X is 0.1 [nm /
13. The optical recording medium according to claim 12, wherein the value is not less than s] and not more than 5.0 nm / s. 14. The phase change material made of the GeSbTe alloy has a ternary phase diagram of (Ge, Sb, Te)
Point (26.0, 19.2, 54.8) and point (21.
0, 21.0, 58.0) and a point (14.3, 28.
6,57.1) and the point (21.6, 24.4, 54.
13. The optical recording medium according to claim 12, wherein the composition is within a region surrounded by 0). 15. The recording film has a thickness of 18 nm to 30 n.
13. The optical recording medium according to claim 12, wherein m is m. 16. The recording film is formed on a substrate. The substrate has a diameter of 120 ± 0.3 mm, a thickness of 0.60 ± 0.03 mm, and a track pitch of 0.8. 13. The optical recording medium according to claim 12, wherein the distance is ± 0.01 μm. 17. A recording film comprising a phase change material in which a phase change between a crystalline state and an amorphous state occurs, and an information signal is recorded by irradiating a light beam to cause a phase change in the recording film. In the method for manufacturing an optical recording medium, a GeSbTe alloy is used as the phase-change material, and when the recording film is formed, an Ar gas atmosphere containing at least one of N ₂ gas and O ₂ gas is used. A method for producing an optical recording medium, comprising forming a film by sputtering. When 18. forming the above recording layer, under an Ar gas atmosphere containing N ₂ gas and O ₂ gas, the mixing ratio of N ₂ gas and O ₂ gas to the Ar gas (N ₂ + O ₂ ) /
The Ar and Y [%], the ratio O ₂ / a O ₂ gas occupying the said N ₂ gas and O ₂ gas (N ₂ + O ₂₎ and Z [%], the deposition rate and X [nm / s] 18. The method for manufacturing an optical recording medium according to claim 17, wherein the film is formed under the condition that X, Y and Z satisfy the following equations (8), (9) and (10). Y ≧ 2.3X + 1.0 (8) Y ≦ 12.8X + 16.7 (9) 10 ≦ Z ≦ 60 (10) 19. The method for manufacturing an optical recording medium according to claim 18, wherein said film forming speed X is set to 0.1 [nm / s] or more and 5.0 [nm / s] or less. 20. As the phase change material, (Ge, S
b, Te), the point (26.0, 1)
9.2, 54.8) and points (21.0, 21.0, 5)
8.0), the point (14.3, 28.6, 57.1),
19. The method for manufacturing an optical recording medium according to claim 18, wherein a GeSbTe alloy having a composition in a region surrounded by the points (21.6, 24.4, 54.0) is used. 21. The recording film has a thickness of 18 nm to 30 n.
19. The method for manufacturing an optical recording medium according to claim 18, wherein m is set to m. When 22. The film forming the recording layer, under an Ar gas atmosphere containing O ₂ gas, the mixing ratio O ₂ / Ar between the O ₂ gas and Ar gas was Y [%], adult Film speed X
18. The method for manufacturing an optical recording medium according to claim 17, wherein when [nm / s] is set, the film is formed under the condition that X and Y satisfy the following formulas (11) and (12). Y ≧ 2.3X + 1.0 (11) Y ≦ 5.5X + 2.7 (12) 23. The method for manufacturing an optical recording medium according to claim 22, wherein said film forming speed X is 0.1 [nm / s] or more and 5.0 [nm / s] or less. 24. As the phase change material, (Ge, S
b, Te), the point (26.0, 1)
9.2, 54.8) and points (21.0, 21.0, 5)
8.0), the point (14.3, 28.6, 57.1),
23. The method of manufacturing an optical recording medium according to claim 22, wherein a GeSbTe alloy having a composition in a region surrounded by the points (21.6, 24.4, 54.0) is used. 25. The recording film has a thickness of 18 nm to 30 n.
The method for manufacturing an optical recording medium according to claim 22, wherein m is set to m. When 26. The film forming the recording layer, under an Ar gas atmosphere containing N ₂ gas, the mixing ratio N ₂ / Ar between the N ₂ gas and Ar gas was Y [%], adult Film speed X
18. The method for manufacturing an optical recording medium according to claim 17, wherein when [nm / s] is set, the film is formed under a condition where X and Y satisfy the following expressions (13) and (14). Y ≧ 1.8X + 5.0 (13) Y ≦ 12.8X + 16.7 (14) 27. The method for manufacturing an optical recording medium according to claim 26, wherein the film forming speed X is set to 0.1 [nm / s] or more and 5.0 [nm / s] or less. 28. As the phase change material, (Ge, S
b, Te), the point (26.0, 1)
9.2, 54.8) and points (21.0, 21.0, 5)
8.0), the point (14.3, 28.6, 57.1),
27. The method for manufacturing an optical recording medium according to claim 26, wherein a GeSbTe alloy having a composition in a region surrounded by the points (21.6, 24.4, 54.0) is used. 29. The recording film having a thickness of 18 nm to 30 n.
27. The method of manufacturing an optical recording medium according to claim 26, wherein m is set to m.