JP2002293029A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording medium capable of dealing with a high density and a high speed and having excellent repeating characteristics, recording/erasing sensitivity and preserving characteristics. SOLUTION: The phase change type optical information recording medium records a recording layer by irradiating the layer with a light and changing a complex refractive index of the layer. The recording layer contains Ge, Ga, Sb, Te and Pd. The recording medium records the layer by irradiating the layer with the light and changing the complex refractive index of the layer. The layer contains Ge, Ga, Sb, Te and Br. The recording medium records the layer by irradiating the layer with the light and changing the complex refractive index. The layer contains Ge, Ga, Sb, Te and Rb. The recording medium records the layer by irradiating the layer with the light and changing the complex refractive index of the layer. The layer contains Ge, Ga, Sb, Te and P.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium, and more particularly, to recording and reproduction of information by irradiating a light beam to cause an optical change in a recording layer made of a phase change material. And a rewritable optical information recording medium.

[0002]

2. Description of the Related Art As one of optical information recording media capable of recording, reproducing and erasing information by laser beam irradiation, a so-called phase-change optical disk utilizing a transition between crystal and non-crystal or between crystal and crystal phases is known. Have been. This can be overwritten by a single beam and the drive side optics is simpler, so it can be used for computer related, video,
It is applied as a recording medium for sound.

The recording materials include GeTe, GeT
eSe, GeTeS, GeSeS, GeSeSb, Ge
AsSe, InTe, SeTe, SeAs, Ge-Te
-(Sn, Au, Pd), GeTeSeSb, GeTe
Sb, Ag-In-Sb-Te and the like. In particular, Ag-
In-Sb-Te has features of high sensitivity and a clear outline of an amorphous portion, and has been developed and applied as a recording layer for mark edge recording (JP-A-3-231889, JP-A-4-19089A). JP, JP-A-4-232
779, JP-A-4-267192, JP-A-5-345478, JP-A-6-166266, and the like.

According to JP-A-3-231889,
I for group I element, III for group III element, V for group V element, VI for VI
As a group III element, a recording layer represented by a general composition formula of type I (III _{1 -γ} V _γ ) · VI ₂ is disclosed. However, this recording layer has a problem in repeated recording characteristics.

[0005] In the case of the recording layer used for the information recording medium disclosed in Japanese Patent Application Laid-Open No. Hei 4-19089, although the improvement of the erasing ratio and the high-speed recording can be achieved, there is a problem in the repetitive recording characteristics. Also, Japanese Patent Application Laid-Open No. 1-303643
The information recording medium disclosed in Japanese Patent Application Laid-Open Publication No. H10-19712 has a high C / N ratio and excellent repetition characteristics and storage reliability by adopting a novel crystal structure, but has a slightly inferior recording / erasing sensitivity. .

[0006] The structure of the unrecorded portion (crystallized portion) of the recording layer used in the information recording medium disclosed in Japanese Patent Application Laid-Open No. Hei 4-232779 has a stable phase (AgSbTe ₂ ) and a structure around the stable phase. It is a mixture of existing amorphous phases. For this reason, although the repetitive recording characteristics are improved, fine crystal grain boundaries exist in the crystallized portion, which causes noise. This is a CD-ROM using a laser beam having a recording / reproducing wavelength of about 780 μm.
Although the recording characteristics of an optical information recording medium having a relatively low recording density such as RW (Compact Disk Rewritable) are not seriously affected, a laser beam having a wavelength of 680 nm or less is used, and the recording density is CD-RW. DVD which is about 4 times of
(Digital Versatile Disk)-This is an obstacle to realizing high-density recording such as RAM and DVD-RW with higher density. Further, there is a problem in the repetitive recording characteristics.

[0007] The structure of the crystallized portion of the recording phase used in JP-A-4-267192 is a mixed phase of AgSbTe ₂ separated from a uniform amorphous phase and another phase (stable phase or amorphous phase). State. When the other phase is an amorphous phase, the above-mentioned JP-A-Hei 4
There is a problem similar to that of the information recording medium disclosed in JP-A-232779, and when the other phase is a stable crystalline phase, as described later, there is a problem that good recording characteristics cannot be obtained. is there.

[0008] JP-A-5-345478, JP-A-6-1994
In the case of JP-A-166268, there is a problem similar to the above case. That, Ag-In-Sb-Te system or these expanded Ib group element, III _b group elements, V _b group element, and an optical information recording medium having a recording layer of phase-change recording material having a VI _b group element Has no knowledge of the recording medium that defines the coordination numbers of the constituent elements, and therefore, there is no prior art which clarifies the function or role of each constituent element as a recording material. For this reason, it has not been possible to theoretically pursue and achieve specific improvements such as the repetition characteristics and the recording and erasing sensitivity of the Ag-In-Sb-Te recording layer.

[0009]

SUMMARY OF THE INVENTION The present invention solves such a conventional problem and provides an optical information recording medium which can respond at high density and high speed and has excellent repetition characteristics, recording / erasing sensitivity and storage characteristics. The task is to do so.

[0010]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have paid attention to the recording layer and made intensive studies on the structural analysis thereof. As a result, the present invention has been completed.

That is, according to the present invention, first, in a phase change type optical information recording medium for recording by irradiating light to change the complex refractive index of the recording layer, the recording layer comprises:
An optical information recording medium comprising Ge, Ga, Sb, Te, and Pd is provided.

In the first invention, the composition ratio (atomic%) of the elements constituting the recording layer is such that 0 <Ge ≦ 52 ≦ Ga ≦ 855 <Sb ≦ 72 18 ≦ Fe ≦ 320 0 <Pd ≦ 7 (where, Ge + Ga + Sb + Te + Pd = 100) is included.

According to the present invention, secondly, in a phase change type optical information recording medium for recording by irradiating light to change the complex refractive index of the recording layer, the recording layer is made of Ge, G
An optical information recording medium characterized by comprising a, Sb, Te and Br is provided.

In the second invention, the composition ratio (atomic%) of the elements constituting the recording layer is 2 <Ge ≦ 73 ≦ Ga ≦ 855 <Sb ≦ 75 20 ≦ Te ≦ 330 <Br ≦ 5 (however, Ge + Ga + Sb + Te + Br = 100) is included.

According to the present invention, thirdly, in a phase change type optical information recording medium for recording by irradiating light to change the complex refractive index of the recording layer, the recording layer is made of Ge, G
An optical information recording medium comprising a, Sb, Te, and Rb is provided.

In the third aspect of the present invention, the composition ratio (atomic%) of the elements constituting the recording layer is such that 0 <Ge ≦ 51 1 ≦ Ga ≦ 755 5 ≦ Sb ≦ 75 18 ≦ Te ≦ 330 0 <Rb ≦ 5 (where, Ge + Ga + Sb + Te + Rb = 100) is included.

According to the present invention, fourthly, in a phase-change optical information recording medium for recording by changing the complex refractive index of the recording layer by irradiating light, the recording layer is made of Ge, G
An optical information recording medium comprising a, Sb, Te and P is provided.

In the fourth invention, the composition ratio (atomic%) of the elements constituting the recording layer is such that 0 <Ge ≦ 52 ≦ Ga ≦ 755 ≦ Sb ≦ 75 20 ≦ Te ≦ 350 0 <P ≦ 5 (where, Ge + Ga + Sb + Te + P = 100) is included.

The first to fourth inventions are directed to an optical information recording medium wherein the recording layer contains at least one element selected from Y, Ba, Nd, Pr, Ce and Er. And the content of at least one element is 2 atomic% or less.

[0020]

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to provide an optical information recording medium which can respond to a high speed at a high density and has good recording sensitivity, repetition characteristics and storage characteristics. The present inventors analyzed the bond coordination number, bond distance, bond energy, and the like between the amorphous phase and the crystalline phase of each element of the recording layer composed of Ag-In-Sb by a wide-area X-ray absorption fine structure, As a result,
Ag and In are additive elements, and Ag can reduce the crystallization speed, In can increase the crystallization acceleration, and explain the experimental results of increasing the crystallization temperature. Sb-Te
The addition of Ga and Pd, which are similar to Ge and In, to the alloy enabled an optical information recording medium that could respond to high-speed operation and had good storage characteristics and repetition characteristics.

The first reason is that Ge has an effect of improving the stability to Sb-Te because of its large binding energy and binding coordination number for Te. Further, Ga has a large atomic radius and a large binding energy with respect to Te, so that it promotes crystallization and contributes to structural stability. On the other hand, Pd is considered to have an effect of promoting crystallization with respect to Sb-Te due to its low viscosity.
By adding Ge, Ga, and Pd to the phase alloy for b-Te, the effects of the respective elements are synergized, so that the crystallization speed is high, that is, it can cope with a high linear velocity and is structurally stable. It seems that an optical information recording medium having good repetition characteristics and storage characteristics can be realized.

At this time, the composition ratio (atomic%) of each element is
It is preferred to be as follows. 0 <Ge ≦ 52 2 ≦ Ga ≦ 8 55 ≦ Sb ≦ 72 18 ≦ Te ≦ 32 0 <Pd ≦ 7 (However, Ge + Ga + Sb + Te + Pd = 100) If the value deviates from this range, the characteristics deteriorate.

In the recording layer of the present invention, Ge, Ga, and Br are added to an Sb-Te alloy to maintain high-speed crystallization and structural stability.

Further, high-speed crystallization is realized by adding Br instead of Pd. Br is low in its own viscosity, and is bonded as one coordination for Group 7 and acts as a terminator, so that crystallization is further promoted.

At this time, the composition ratio (atomic%) of each element is
It is preferred to be as follows. 2 <Ge ≦ 73 3 ≦ Ga ≦ 85 55 ≦ Sb ≦ 75 20 ≦ Te ≦ 330 0 <Br ≦ 5 (However, Ge + Ga + Sb + Te + Br = 100) Next, the recording layer of the present invention is made of an Sb-Te alloy. Ge
And the effects of Ge and Ga are the same as above. Rb has a very large atomic radius and a small viscosity, so the crystallization rate is considered to be very high. It is considered to be suitable for a material that realizes speeding up.

At this time, the composition ratio (atomic%) of each element is
It is preferred to be as follows. 0 <Ge ≦ 71 1 ≦ Ga ≦ 75 55 ≦ Sb ≦ 75 18 ≦ Te ≦ 330 0 <Rb ≦ 5 (However, Ge + Ga + Sb + Te + Rb = 100)

The recording layer of the present invention is obtained by adding Ge, Ga and P to an Sb-Te alloy. It is considered that P also promotes crystallization due to extremely low viscosity. At this time, the composition ratio (atomic%) is preferably as follows. 0 <Ge ≦ 5 2 ≦ Ga ≦ 7 55 ≦ Sb ≦ 75 20 ≦ Te ≦ 35 0 <P ≦ 5 (However, Ge + Ga + Sb + Te + P = 100)

Further, in the recording layer of the present invention, at least one element obtained from Y, Ba, Nd, Pr, Ce and Br is added to the above-mentioned recording layer. These elements are considered to have a large atomic radius to accelerate the crystallization rate, and are considered to be able to cope with further higher linear velocity in addition to the above-mentioned Pd, Br, Rb, and P.

At this time, Y, Ba, Nd, Pr, Ce,
The addition amount of Er is 2 atomic% or less. If the amount is larger than this, the stability of the amorphous is lost even if Ge is added, which is not preferable.

Next, the configuration of the optical information recording medium of the present invention will be described with reference to the drawings. FIG. 1 shows an example of the configuration of an optical information recording medium according to the present invention, in which a lower heat-resistant protective layer 2, a recording layer 3, an upper heat-resistant protective layer 4, and a reflective heat dissipation layer 5 are provided on a substrate 1. The heat-resistant protective layer is not necessarily provided on both sides of the recording layer. However, when the substrate 1 is made of a material having low heat resistance such as a polycarbonate resin, it is desirable to provide the lower heat-resistant layer 2.

The material of the substrate 1 is usually glass, ceramics or resin, and a resin substrate is suitable in terms of moldability and cost. Examples of the resin include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, urethane resin, and the like. A polycarbonate resin is preferred from the viewpoint of optical characteristics and the like. The shape of the substrate may be any one of a disk shape, a card shape, and a sheet shape.

The heat-resistant protective layer, that is, the dielectric layer is made of (Zn
S) A film is formed by sputtering using ₈₀ · (SiO ₂ ) ₂₀ . Since the present dielectric layer also has a function as a heat-resistant protective layer and a function as a light interference layer, it is necessary to make the most of these functions, and for that purpose, the film thickness is preferably 200 to 3000 mm. Is 350 ~ 2000Å
And If it is less than 200 °, the function as a heat-resistant protective layer is lost, and if it exceeds 3000 °, interface peeling is likely to occur, which is not desirable.

The recording layer 3 of the present invention is generally formed by a sputtering method and has a thickness of 100 °.
Å1000 °, preferably 200Å350 °.
If the thickness is less than 100 °, the light absorbing ability is reduced and the function as the recording layer is lost. If the thickness is more than 1000 °, the transmitted light is reduced and the interference effect cannot be expected. The reflective heat dissipation layer 5 is made of an Al alloy, and the film is formed by a sputtering method. 500Å
Å2000Å, preferably 700Å1500Å.

[0034]

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

Examples 1 to 8 and Comparative Examples 1 to 4 Track pitch 0.7 μm, groove depth 400 °, thickness 0.1 mm
On a 6 mm, 120 mm diameter polycarbonate substrate,
The recording layers of Examples 1 to 8 and Comparative Examples 1 to 4 having the configurations shown in Table 1 were formed by depositing ZnS and SiO ₂ dielectric layers by sputtering.
After providing 2,000 mm, 200 mm is provided, and ZnS / Si is further provided.
An O ₂ dielectric and an Al alloy layer were sequentially provided by a sputtering method. The film thickness at this time is 350 ° and 1200 °.
Next, after initial crystallization of the obtained optical information recording medium,
The signal characteristics and storage characteristics were evaluated. The condition is that a light source with a wavelength of 635 nm is used and the recording linear velocity is 10 m /
s, 12m / s, 14m / s, 16m / s, FFM
Overwrite is repeatedly recorded in a random pattern, and the jitter of the 3T signal at that time is reduced by a recording power of 15 mw.
Was evaluated. The storage characteristics were evaluated after storage at 80 ° C. and 85% for 200 hours. The results are shown in Tables 2 and 3.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

From Tables 1, 2 and 3, the Ge of the recording layer of the present invention is shown.
-Ga-Pd-Sb-Te, Ge-Ga-Br-Sb-
Te, Ge-Ga-Rb-Sb-Te, Ge-Ga-P
-Sb-Te, and Ge-Ga-P in these materials
It was found that the optical information recording medium obtained from the recording layer in which Y, Ba, Ce, and Nd were added to d-Sb-Te exhibited excellent repetition characteristics and storage characteristics at a high linear velocity. Although not described in the embodiments, Y, Ba, Ce, Nd
It has been found that the addition of these elements is also effective for recording layers other than Ge-Ga-Pd-Sb-Te. Further, similar results were obtained when Si was used instead of Ge and Al-In was used instead of Ga.

[0040]

According to the present invention, there is provided an optical information recording medium which can respond at a high density and a high speed and has excellent repetition characteristics, recording / erasing sensitivity and storage characteristics, and greatly contributes to the optical information recording field. It is big.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an optical information recording medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Lower heat protection layer 3 Recording layer 4 Upper heat protection layer 5 Reflection heat dissipation layer

Continued on the front page (72) Inventor Hajime Yonehara 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Nobuaki Onagi 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Hiroko Tashiro 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Yuji Miura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Invention Person Yoshiyuki Kageyama 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H111 EA04 EA23 FB05 FB09 FB12 FB17 FB18 FB20 FB21 FB22 FB26 FB28 FB30 5D029 JA01 JB35 JC17 JC18 JC20

Claims (10)

[Claims] 1. A phase change type optical information recording medium for recording by irradiating light to change a complex refractive index of a recording layer, wherein the recording layer is made of Ge, Ga, Sb, Te and Pd. Characteristic optical information recording medium. 2. The composition ratio (atomic%) of the elements constituting the recording layer is as follows: 0 <Ge ≦ 52 2 ≦ Ga ≦ 855 5 ≦ Sb ≦ 72 18 ≦ Fe ≦ 32 0 <Pd ≦ 7 (However, Ge + Ga + Sb + Te + Pd) = 100). 3. A phase change type optical information recording medium for recording by changing the complex refractive index of a recording layer by irradiating light, wherein the recording layer is composed of Ge, Ga, Sb, Te and B.
An optical information recording medium comprising: r. 4. The composition ratio (atomic%) of the elements constituting the recording layer is as follows: 2 <Ge ≦ 73 ≦ Ga ≦ 8.55 ≦ Sb ≦ 75 20 ≦ Te ≦ 330 <Br ≦ 5 (where, Ge + Ga + Sb + Te + Br) = 100). 5. A phase-change optical information recording medium for recording by irradiating light to change the complex refractive index of the recording layer, wherein the recording layer is made of Ge, Ga, Sb, Te and Rb. Characteristic optical information recording medium. 6. The composition ratio (atomic%) of elements constituting the recording layer is as follows: 0 <Ge ≦ 51 1 ≦ Ga ≦ 755 ≦ Sb ≦ 75 18 ≦ Te ≦ 330 0 <Rb ≦ 5 (However, Ge + Ga + Sb + Te + Rb) = 100). The optical information recording medium according to claim 5, wherein 7. A phase-change optical information recording medium for recording by irradiating light to change the complex refractive index of the recording layer, wherein the recording layer is made of Ge, Ga, Sb, Te and P. Characteristic optical information recording medium. 8. The composition ratio (atomic%) of the elements constituting the recording layer is as follows: 0 <Ge ≦ 52 2 ≦ Ga ≦ 755 ≦ Sb ≦ 75 20 ≦ Te ≦ 35 0 <P ≦ 5 (where, Ge + Ga + Sb + Te + P = 100). The optical information recording medium according to claim 7, wherein 9. The recording layer according to claim 1, wherein Y, Ba, Nd, Pr, C
The optical information recording medium according to any one of claims 1 to 8, comprising at least one element selected from e and Er. 10. The Y, Ba, Nd, Pr, Ce and E
10. The optical information recording medium according to claim 9, wherein the content of at least one element selected from r is 2 atomic% or less.