JP2003211849A - Optical recoding medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium capable of coping with a high speed overwrite recording while having a superior preservation reliability and a better characteristic for repeatedly recording. <P>SOLUTION: The optical recording medium is a phase-change recording medium on which data is recorded by causing a phase transition of a recording layer from a crystal phase to an amorphous phase by irradiation with light. When the composition formula of the recording layer is defined as GeαGaβMnγSbδTeε (α, β, γ, δ and ε are atom.%, α+β+γ+δ+ε=100), the optical recording medium satisfies the following conditions; 0<α≤7, 0<β≤7, 5≤γ≤10, 60≤δ≤70 and 15≤ε≤25. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rewritable optical recording medium for recording / reproducing information by irradiating a light beam to optically change a recording layer made of a phase change material. Is.

[0002]

2. Description of the Related Art An optical recording medium capable of recording / reproducing / erasing information by irradiating a semiconductor laser beam has a magneto-optical recording system for recording / reproducing / erasing by reversing magnetization by utilizing heat. Recording using reversible phase change between crystalline and amorphous
There is a phase change recording method that reproduces and erases. The phase change recording method is capable of single-beam overwriting and is characterized by a simpler optical system on the drive side, and is applied as a recording medium related to computers and audiovisual. As a recording material, various compounds centered on chalcogen and alloys with a composition near the eutectic are used because amorphous compounds are easily formed and composition segregation does not easily occur even after repeated recording. A mixture of GeTe and Sb ₂ Te ₃ and Sb
There is a system in which Ag or In is added to the -Sb ₂ Te ₃ pseudo binary eutectic composition. In particular, the latter is a material with high sensitivity and a clear outline of the amorphous portion, and is suitable for high density recording. For example, Japanese Patent Laid-Open No. 11-070738 (prior application of the present applicant)
Discloses an optimum composition ratio and an optimum layer structure of a quaternary material composed of AgInSbTe, which has a high overwrite count and excellent storage reliability. Further, the storage characteristics are further improved by adding Cr or Zr.

In recent years, the use of phase change recording media for high-density image recording has expanded, and even higher speed overwriting has been realized (7 to 17 m / s, which is 2 to 5 times the linear velocity of reproduction of DVD-ROM). However, in order to realize high-speed overwrite, it is necessary to speed up the crystallization of the recording layer material at the time of erasing marks. In response to this requirement, the composition formula of the recording layer is XαSbβTeγ (where X is I
n and / or Ga, α, β, γ are atomic%),
α, β and γ are set to 0.01 ≦ α ≦ 0.1 0.60 ≦ β ≦ 0.90 γ = 1-α-β to accelerate the crystallization rate of the recording layer, and then It is known that the above-mentioned problems can be solved by optimizing the types, the film thicknesses thereof, and the production method (Japanese Patent Application 2).
001-79830).

However, according to the findings of the present inventors, Ga
Is extremely effective in increasing the crystallization speed of the recording layer material when erasing marks, and is a material suitable for realizing high-speed overwriting, but the crystallization temperature of the recording layer rises as the amount of addition increases, and the initial crystallinity increases. However, there is a problem in that it is difficult to realize the above-mentioned characteristics, and further, there is a problem in that repetitive recording characteristics are deteriorated. Then, any of the problems tends to become remarkable especially when the added amount exceeds 5 atomic%. These problems can be avoided by reducing the amount of Ga added, but in that case, the proportion of Sb must be increased to compensate for the decrease in the crystallization rate due to the reduction of the amount added. In fact, according to the knowledge obtained by the present inventors, it is necessary that the proportion of Sb is at least 70 atomic% or more, but if the proportion of Sb exceeds 70 atomic%, the storage reliability is greatly reduced. As a result, the recording layer in which the added amount of Ga is decreased and the ratio of Sb is increased to increase the crystallization rate may be easy for initial crystallization and may be compatible with high linear velocity recording, but is practically sufficient. It is difficult to obtain storage reliability.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical recording medium which solves the above problems, can cope with high speed overwriting, is excellent in storage reliability, and is easy to undergo initial crystallization.

[0006]

[Means for Solving the Problems] The above problems are solved in the following 1) to
It is solved by the invention of 12). 1) In a phase-change recording medium in which information is recorded by irradiating light, the recording layer undergoes a phase transition from a crystalline phase to an amorphous phase, and the composition formula of the recording layer is GeαGaβMnγSbδT
eε (α, β, γ, δ, ε is atomic%, α + β + γ + δ +
An optical recording medium characterized by satisfying the following conditions when ε = 100). 0 <α ≦ 7 0 <β ≦ 7 5 ≦ γ ≦ 10 60 ≦ δ ≦ 70 15 ≦ ε ≦ 25 2) The crystallization temperature of the recording layer is 160 ° C. or more and less than 200 ° C. 1) Description Optical recording medium. 3) The substrate has at least a first thin film layer, a recording layer, a second thin film layer, and a reflective layer in this order, and the recording layer has a thickness of 14 to 2
The optical recording medium according to 1) or 2), which has a thickness of 0 nm. 4) The optical recording medium according to 3), wherein the reflective layer is made of Ag or an alloy containing 90 atomic% or more of Ag. 5) The second thin film layer is a mixture of ZnS and SiO ₂ or Z
It is a mixture of nS and ZrO ₂ 3)
Alternatively, the optical recording medium according to 4). 6) The optical recording medium according to any one of 3) to 5), characterized in that a third thin film layer containing no sulfur is provided between the second thin film layer and the reflective layer. 7) The optical recording medium according to 6), wherein the third thin film layer comprises a layer containing Si or SiC as a main component. 8) The optical recording medium according to 6) or 7), wherein the thickness of the third thin film layer is 2 to 20 nm. 9) The optical recording medium according to any one of 1) to 8), which has a recording layer formed by a sputtering method using an alloy target having a predetermined composition containing an element forming the recording layer. 10) The optical recording medium according to any one of 1) to 9), which is an initially crystallized one. 11) The optical recording medium according to 10), wherein the initial crystallization is performed by a melting initialization method using a laser beam or a solid phase initialization. 12) 1 <characterized in that 0 <α + β <10
The optical recording medium according to any one of 1 to 11).

The present invention will be described in detail below. The recording layer of the present invention is mainly composed of Sb and Te. However, the recording layer material composed of only Sb and Te has a crystallization temperature of about 120 ° C., and therefore, the crystal of the recording mark is long-term. However, the mark disappears and there is a problem in storage characteristics. Further, there is a problem that it is difficult to support high linear velocity recording, for example, high-speed crystallization capable of overwriting depending on the linear velocity of 15 m / s or more. In the prior art, in order to solve these problems, Ga and Ge have been used as additive elements, but since there are various problems as described above,
In the present invention, in addition to Ga and Ge, Mn is further added as an additional element. Here, according to the findings obtained by the present inventors from actual evaluation of medium characteristics, Mn has almost no change in the crystal temperature of the recording layer due to addition, does not impair repetitive recording characteristics, and has a recording property. It has the effect of increasing the crystallization rate of the layer. In this respect, the addition effect is similar to the case where the proportion of Sb is increased. Moreover, Sb
In the case of Mn, there was a problem that the storage property was deteriorated when the ratio was increased, but in the case of Mn, the storage property was not deteriorated.

As described above, from the viewpoint of the characteristics of the recording layer of the present invention as an optical recording medium, it can be considered that a part of Sb is replaced with Mn, and the recording material can be used without increasing the proportion of Sb. Since the crystallization rate can be increased, high-speed overwrite can be realized even in the composition range in which the Sb ratio is less than 70 atomic%. As a result, there is an excellent effect that the problem of deterioration in storage reliability that occurs when the proportion of Sb exceeds 70 atomic% does not occur. Further, since the crystallization rate can be increased to the same extent as when the amount of Sb is increased by adding Mn, it was necessary to improve the crystallization rate.
It is possible to reduce the amount of a added, and it is possible to support high-speed overwrite even if the proportion of Ga is reduced.
That is, even if the amount of Ga added to improve the crystallization rate is within the above composition range, high-speed overwriting is possible. As a result, it is possible to suppress an increase in the crystallization temperature due to the addition of Ga, and it is possible to easily perform the initial crystallization.

Next, the ratio of each constituent element of the recording layer will be described. It is desirable that the amount of Mn added be 5 atom% or more and 10 atom% or less. If it is less than 5 atomic%, it is not possible to satisfy all of high-speed overwrite support, storage characteristics, and initial crystallization easiness. That is, if it is attempted to realize high-speed overwrite support while maintaining the storage characteristics by setting the Sb content to 70 atomic% or less, the crystallization temperature becomes high and the initial crystallization becomes difficult because the amount of Ga added must be increased. Become. Further, if it is attempted to realize high-speed overwrite support after reducing the amount of Ga added and ensuring the easiness of initial crystallization, it is necessary to increase the proportion of Sb to more than 70 atomic%, which is a storage characteristic that is practically sufficient. Cannot be secured. When it exceeds 10 atomic%, the overwrite characteristic is deteriorated, which is not preferable. It is desirable that the added amounts of Ge and Ga are each 7 atomic% or less. When the amount of Ge is larger than this, the overwrite characteristic is deteriorated, and when the amount of Ga is larger than this, the overwrite characteristic is deteriorated and initial crystallization becomes very difficult. On the other hand, since the effect of addition becomes unclear as the amount of addition decreases, it is desirable to add 1 atom% or more.

Sb is preferably 60 to 70 atomic%. If it is less than 60 atom%, it is difficult to cope with high-speed overwrite, and if it exceeds 70 atom%, it is difficult to secure practically sufficient storage reliability. Te is preferably 15 to 25 atomic%. If it is less than 15 atom%, it becomes difficult to amorphize, and if it exceeds 25 atom%, it is difficult to cope with high-speed overwrite. The crystallization temperature of the recording layer is 160 ° C.
It is preferably above 200 ° C. If it is lower than 160 ° C, it is difficult to secure practically sufficient storage reliability, and if it is 200 ° C or higher, initial crystallization becomes difficult. In order to set the crystallization temperature of the recording layer to less than 200 ° C., in addition to setting the composition range of Ga and Ge, which are the additional elements having the action of improving the crystallization rate of the recording layer, to the above range, G
It is preferable that the total amount of a and Ge added is less than 10%.

Next, the construction of the optical recording medium of the present invention is shown in the drawings.
It will be explained based on. FIG. 1 shows the layer structure of the optical recording medium of the present invention.
The first thin film layer 2 is formed on the substrate 1,
The recording layer 3, the second thin film layer 4, and the reflection layer (heat dissipation layer) 5 are provided.
Has been. As the material for the first and second thin film layers, SiO
x, ZnO, SnO_Two, Al_TwoO_Three, TiO_Two, In_Two
O_Three, MgO, ZrO_Two, Ta_TwoO₅Oxides such as Si
_ThreeN _Four, AlN, TiN, BN, ZrN and other nitrides; Z
nS, TaS_FourSulfides such as SiC, TaC, B_FourC,
Carbides such as WC, TiC, and ZrC are listed. these
The material can be used alone as a protective layer, and
It can also be used as a mixture. As a concrete example of a mixture
For ZnS, SiOx, Ta_TwoO₅And SiOx
To be The physical properties of these materials include thermal conductivity and ratio.
Heat, melting point, coefficient of thermal expansion, refractive index and substrate material or recording layer
Adhesion with materials, etc. can be mentioned, but the melting point is high and thermal expansion
Physical properties such as low coefficient and good adhesion are required.
It

[0012] Here, the second thin film layer has a role of storing the heat applied to the recording layer by laser light irradiation at the time of recording to store the heat and at the same time, transferring the heat to the reflecting layer to release the heat. Repeatedly affects overwrite characteristics. According to the knowledge of the present inventors, it is preferable to use a mixture of ZnS and SiO ₂ or a mixture of ZnS and ZrO ₂ as the material of the second thin film layer, and especially ZnS and ZrO ₂ from the viewpoint of thermal stability. A mixture with ₂ is preferred. In addition, ZrO
When _two, in order to stabilize the ZrO ₂ (eliminate structural change at high temperatures), _Y 2 O with respect to ZrO _2
3 , 2 to 10 mol% of CaO, MgO or rare earth oxide
It is preferable to use the added one.

The thickness of the first thin film layer is 50 to 250 nm, preferably 75 to 200 nm. When the thickness is less than 50 nm, the environment resistance protection function, the heat resistance, and the heat storage effect are deteriorated, which is not preferable. On the other hand, if the thickness is more than 250 nm, film peeling or cracks may occur due to an increase in the film temperature in the film forming process by the sputtering method or the like, and the sensitivity at the time of recording may be decreased, which is not preferable. The thickness of the second thin film layer is 10 to 100 nm, preferably 15 to 50 n.
m. When the thickness is less than 10 nm, the heat resistance is essentially lowered, which is not preferable. On the other hand, if it exceeds 100 nm, it is not preferable because the recording sensitivity is lowered, the film is peeled off due to the temperature rise, the deformation and the heat radiation property are deteriorated so that the repetitive overwrite characteristic is deteriorated. The thickness of the recording layer is preferably 10 to 30 nm, more preferably 14 to 20 nm. If it deviates from this range, the recording sensitivity and the repetitive overwrite characteristic are deteriorated.

While the reflecting layer plays a role of reflecting light, it also plays a role of a heat-dissipating layer for escaping heat stored in the recording layer due to laser light irradiation during recording. The formation of the amorphous mark is greatly influenced by the cooling rate due to heat dissipation, and therefore the selection of the reflective layer is particularly important in the medium corresponding to the high linear velocity. Therefore, as the reflective layer material of the present invention, Au, A
It is preferable to use g, Al, or an alloy containing these elements as a main component, but A having a very high thermal conductivity is preferable.
When an alloy containing g or Ag as a main component (preferably containing 90 atomic% or more of Ag) is used, the cooling rate is increased and good amorphous formation can be realized. The thickness of the reflective layer is preferably 100 to 300 nm. The heat dissipation ability of the reflective layer is basically proportional to the film thickness, and if it is less than 100 nm, the cooling rate is lowered, which is not preferable. On the other hand, when it exceeds 300 nm, the material cost is increased. In addition, when the reflective layer is provided in contact with the second thin film layer using the above-mentioned Ag or an alloy containing Ag as a main component, and the second thin film layer is made of a material containing S, sulfurization of Ag is performed. In order to avoid the generation of pinholes due to the contact between the two layers, Si, SiC, SiN, Ge
It is preferable to provide a third thin film layer containing no sulfur such as N or ZrO ₂ as the barrier layer. Among them, Si is particularly preferable because it has good adhesion to Ag and good repeatability. The thickness of the third thin film layer is 2 to 20 nm, preferably 4 to 10 nm. When it is less than 2 nm, it does not function as a barrier layer, and when it exceeds 20 nm, the recording sensitivity is lowered.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1 Diameter 12 cm, thickness 0.6 mm, track pitch 0.7
After dehydrating a polycarbonate disc substrate with a groove of 4 μm at a high temperature, a first thin film layer, a recording layer, a second thin film layer, and a reflection heat dissipation layer were sequentially formed on this substrate by sputtering. A ZnS.SiO ₂ target was used for the first thin film layer, and the film thickness was 180 nm. In the recording layer, the composition ratio is Ga
_An alloy target of ₅ Ge ₃ Mn ₆ Sb ₆₈ Te ₁₈ was used, and sputtering was performed at an argon gas pressure of 3 × 10 ⁻³ torr and an RF power of 300 mW to obtain a film thickness of 20 nm. For the second thin film layer, the same ZnS.SiO ₂ target as the first thin film layer was used, and the thickness was set to 20 nm. In the reflective heat dissipation layer,
The thickness was set to 120 nm using an Al.Ti alloy target. Next, an organic protective film of acrylic UV curable resin having a thickness of 5 to 10 μm is applied onto the reflection / heat dissipation layer by spinner, and then UV cured, and further, a diameter of 12 c.
Polycarbonate discs having a thickness of 0.6 mm and a thickness of 0.6 mm were bonded together with an adhesive sheet, and the recording layer was initially crystallized by irradiation with a large-diameter LD beam to obtain an optical recording medium. A pickup having a wavelength of 656 nm and an NA of 0.65 was used for recording and reproduction. The pulse modulation method is used for recording, and the recorded data is
The optimum recording linear velocity according to the recording layer by the EFM + modulation method,
Recording was performed with the optimum recording power. The recording strategies were also optimized and used so that the jitter was minimized. All reproduction was performed at a power of 0.7 mW and a linear velocity of 3.5 m / s, and dat
A to clock (data to clock) jitter and reflectance were measured. As a result, the recording density is 0.
It was found that good recording was possible up to a recording linear velocity of 17.5 m / s at 267 μm / bit, and the jitter σ / Tw after both initial recording and 1000 times repeated recording was 10%.
A value of less than was obtained. Further, this recording medium (disk) was subjected to a storage test at 70 ° C. and 85% RH for 1000 hours. As a result, no deterioration was observed in the initial recording and after 1000 times of repeated recording.

Examples 2 to 3 The composition of the recording layer was changed to Ga ₃ Ge ₃ Mn ₇ Sb ₆₉ Te.
₁₈ (Example 2), Ga ₄ Ge ₃ Mn ₉ Sb ₆₅ Te
₁₉ An optical recording medium was prepared and evaluated in the same manner as in Example 1 except that (Example 3) was changed. As a result, Example 1
Similarly, it was found that good recording was possible at a recording density of 0.267 μm / bit up to a recording linear velocity of 17.5 m / s, and the jitter σ / Tw after both the initial recording and the repeated recording 1000 times was 10 A value of less than% was obtained. Furthermore, regarding this optical recording medium (optical disk), 70 ° C. 8
When a storage test was performed for 1000 hours under a 5% RH environment, no deterioration was found in both the initial recording and 1000 times of repeated recording.

Comparative Example 1 An optical recording medium was prepared and evaluated in the same manner as in Example 1 except that the composition of the recording layer was changed to Ga ₅ Ge ₃ Sb ₇₆ Te ₁₆ . As a result, the recording density is 0.2 as in the first embodiment.
Good recording is possible at a recording linear velocity of 17.5 m / s at 67 μm / bit, and initial recording and repeated recording 100
The values of the jitter σ / Tw after 0 times were both less than 10%. However, 1 at 70 ° C and 85% RH
After storage for 000 hours, it was found that even in the first-time recording part, it increased to 12%, and practically sufficient storage reliability could not be obtained. It is considered that this is because the storage reliability was lowered because the ratio of Sb exceeded 70 atomic%.

Comparative Examples 2-4 The composition of the recording layer is Ga₅Ge_ThreeMn_4.5Sb_69.5T
e₁₈(Comparative example 2), Ga₅Ge_ThreeMn_4.5Sb₇₁
Te_16.5(Comparative Example 3), Ga₇Ge_ThreeMn _4.5S
b_69.5Te₁₆Except that it was changed to (Comparative Example 4),
An optical recording medium was prepared and evaluated in the same manner as in Example 1. That
As a result, the medium of Comparative Example 2 has the same recording density as in Example 1.
Good recording linear velocity of 15m / s at 0.267μm / bit
Various recordings are possible, and 100 at 70 ° C and 85% RH
When a 0-hour storage test was performed, the initial recording and
Deterioration was not seen after 1,000 times of repeated recording.
Initial recording and repetitive recording at recording linear velocity of 17.5 m / s
After 1000 times, the jitter σ / Tw both became 15%,
Good recording could not be performed. In addition, Comparative Example 3
The recording medium has a recording density of 0.267 μm as in the first embodiment.
/ Bit enables good recording up to a recording linear velocity of 15 m / s
There was, but stored at 70 ℃ 85% RH environment for 1000 hours
However, even in the first recording part, it has risen to 12%,
It has been found that practically sufficient storage reliability cannot be obtained. Well
Also, the medium of Comparative Example 3 could not be initially crystallized.
It was. From these results, the addition amount of Mn is less than 5 atom%.
Therefore, high-speed recording, storage reliability, and ease of initialization
I find it difficult to satisfy all.

Examples 4 to 5 A was used as the reflective heat dissipation layer instead of the Al.Ti alloy target.
An optical recording medium was prepared in the same manner as in Examples 1 and 2 except that a Si film having a thickness of 5 nm was provided as a third thin film layer between the second thin film layer and the Ag reflection / heat dissipation layer using g. (Example 1
→ Example 4, Example 2 → Example 5), and evaluation was performed in the same manner as in Example 1. The optical recording medium of Example 4 was compared with Example 1 and the optical recording medium of Example 5 was compared with Example 2. As a result, the jitter σ /
It was found that the characteristics were improved with respect to Tw. Furthermore,
About these optical recording media (discs), 70 ° C 85
When a storage test was performed for 1000 hours in a% RH environment, no deterioration was observed in the initial recording and after 1000 times of repeated recording, and no defects due to sulfurization of Ag were also observed.

Example 6 ZnS-Z was used instead of ZnS-SiO ₂ as the second thin film layer.
An optical recording medium was prepared in the same manner as in Example 3 except that rO ₂ was used, and compared with the optical recording medium of Example 3,
It was found that the characteristics of the jitter σ / Tw after 1000 times of repeated recording were improved.

Comparative Example 5 An optical recording medium was prepared and evaluated in the same manner as in Example 1 except that the initial crystallization of the recording layer was performed by lamp annealing. As a result, the reflectance was uniform, but recording that could be evaluated was not possible even by adjusting the recording strategy and power. Therefore, the crystal structure of a thin film obtained by sputtering only the recording layer on a glass substrate and crystallized by an LD beam and lamp annealing was examined by a powder X-ray diffraction method. Single Na
While a diffraction spectrum that was considered to be due to a crystal phase close to the Cl structure was obtained, the film crystallized by lamp annealing was not a single crystal phase, but a hexagonal crystal or Sb that was estimated to accompany the precipitation of InSb. The appearance of trigonal crystals presumed to accompany the precipitation of ₂ Te ₃ was observed. Therefore, it is considered that recording cannot be performed due to this difference in crystal structure.

Comparative Example 6 In the recording layer forming process of Example 1, Ga ₅ Ge ₃ Mn was used.
₆ instead of the alloy target of Sb ₆₈ Te _18, on Sb-Te alloy target having a predetermined composition, Sb, Ga, Mn
Sputtering was performed by mounting the Ge chips and Ge chips, but it was difficult to obtain a recording layer having a desired composition, and it was not possible to stably form a recording layer having the same composition.

[0024]

According to the present invention 1, the Ga addition amount and Sb
It is possible to provide an optical recording medium which can realize high-speed overwriting with a recording layer composition in which the ratio of the ratio is suppressed, has excellent storage reliability, and is easy to perform initial crystallization. According to the second aspect of the present invention, it is possible to provide an optical recording medium that can cope with high-speed overwriting, has excellent storage reliability, and is easy to undergo initial crystallization. According to the present inventions 3 to 5, recording sensitivity and high-speed overwrite characteristics can be further improved. According to the present inventions 6 to 7, it is possible to prevent sulfuration of the reflective layer and prevent deterioration of storage reliability. Further, in the case of using Si of the present invention 7 as a main component, since the adhesiveness with the reflective layer is good, it is possible to stably provide a more reliable optical recording medium. According to the present invention 8,
It is possible to reliably prevent sulfurization of the reflective layer without impairing the recording sensitivity, and to provide an optical recording medium with excellent reliability. According to the ninth aspect of the present invention, the composition of the recording layer for each film formation is stable, so that an optical recording medium of constant quality can be stably provided. According to the present inventions 10 to 11, it is possible to provide an optical recording medium capable of high-density recording and excellent in repetitive recording characteristics in a state where good recording is possible. According to the twelfth aspect of the present invention, it is possible to provide an optical recording medium having further excellent initial crystallization characteristics.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a layer structure of an optical recording medium of the present invention.

[Explanation of symbols]

1 substrate 2 First thin film layer 3 recording layers 4 Second thin film layer 5 Reflective layer (heat dissipation layer)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11B 7/24 G11B 7/24 535G 535 535H 538E 538 7/26 531 7/26 531 B41M 5/26 X ( 72) Inventor Hajime Jyohara 1-3-6 Nakamagome, Tokyo, Ota-ku, Tokyo (72) Inventor Yoshiyuki Kageyama 1-3-3 Nakamagome, Tokyo, Ota-ku, Tokyo (72) Inventor Eiko Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo (72) Inventor Hiroko Tashiro 1-3-3 Nakamagome, Nakamagome, Ota-ku, Tokyo (72) Inventor Mizutani Mirai Tokyo 1-3-6 Nakamagome, Ota-ku Ricoh Co., Ltd. (72) Inventor Mikiko Abe 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Association Company Ricoh F-term (reference) 2H111 EA04 EA12 EA23 FA12 FA14 FA21 FA23 FA24 FA25 FA27 FA29 FB05 FB09 FB12 FB16 FB21 FB30 GA03 5D029 JA01 JB35 LA12 LA13 LA14 LA15 LA17 LB01 EE01 5D090 AA0114D05 11A1414

Claims (12)

[Claims] 1. A phase-change recording medium in which information is recorded by irradiating light with the recording layer undergoing a phase transition from a crystalline phase to an amorphous phase, and the composition formula of the recording layer is GeαGaβMnγ.
SbδTeε (α, β, γ, δ, ε are atomic%, α + β +
An optical recording medium characterized by satisfying the following conditions when γ + δ + ε = 100). 0 <α ≦ 7 0 <β ≦ 7 5 ≦ γ ≦ 10 60 ≦ δ ≦ 70 15 ≦ ε ≦ 25 2. The crystallization temperature of the recording layer is 160 ° C. or higher 20
The optical recording medium according to claim 1, wherein the temperature is lower than 0 ° C. 3. A substrate having at least a first thin film layer, a recording layer, a second thin film layer and a reflective layer in this order, and the thickness of the recording layer is 14 to 20 nm. 2. The optical recording medium according to 2. 4. The optical recording medium according to claim 3, wherein the reflective layer is made of Ag or an alloy containing 90 atomic% or more of Ag. 5. The optical recording medium according to claim 3, wherein the second thin film layer is a mixture of ZnS and SiO ₂ or a mixture of ZnS and ZrO ₂ . 6. A third thin film layer containing no sulfur is provided between the second thin film layer and the reflective layer.
6. The optical recording medium according to any one of 5 above. 7. The optical recording medium according to claim 6, wherein the third thin film layer is a layer containing Si or SiC as a main component. 8. The optical recording medium according to claim 6, wherein the thickness of the third thin film layer is 2 to 20 nm. 9. The optical recording according to claim 1, further comprising a recording layer formed by a sputtering method using an alloy target having a predetermined composition containing an element forming the recording layer. Medium. 10. The optical recording medium according to claim 1, wherein the optical recording medium is initially crystallized. 11. The optical recording medium according to claim 10, wherein the initial crystallization is performed by a melting initialization method using a laser beam or a solid phase initialization. 12. The optical recording medium according to claim 1, wherein 0 <α + β <10.