JP2003231354A - Optical information recording medium - Google Patents

Abstract

(57) [Problem] To provide an optical information recording medium (hereinafter, sometimes simply referred to as a recording medium) which can cope with high linear velocity and high density and has excellent repetition characteristics and storage characteristics. SOLUTION: A substrate has at least a first heat-resistant protective layer, a recording layer, a second heat-resistant protective layer, a reflective heat-radiating layer, and an environmental protective layer to form a layer structure, and is irradiated with electromagnetic waves,
In a phase-change optical recording medium for recording, reproducing, and erasing information, this recording layer comprises Ga, Sb, and B;
Ag, Cu, Ge, Sn, Zn, In, Se,
An optical recording medium comprising an alloy obtained by adding at least one element selected from N, Ni, Ti, V, Cr, Mn, and Co.

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 specifically, by irradiating a light beam, an optical change is caused in a recording layer made of a phase change material to record and reproduce information. Or, it relates to a rewritable optical information recording medium for erasing.

[0002]

2. Description of the Related Art As one of optical information recording media capable of recording, reproducing or erasing information by irradiating a light beam, a so-called phase change type optical disk utilizing a transition between a crystalline-amorphous phase or a crystalline-amorphous phase. It has been known. Since this optical disc can be overwritten by a single beam and the optical system on the drive side is simpler, it is applied as a recording medium for computer-related hardware, video, and sound.

As the recording material, GeTe, GeT
eSe, GeTeS, GeSeS, GeSeSb, Ge
AsSe, InTe, SeTe, SeAs, Ge-Te
-(Sn, Au, Pd), GeTeSeSb, GeTe
Sb, Ag-In-Sb-Te, etc. are used. In particular, Ag-In-Sb-Te is characterized by having high sensitivity and a clear outline of an amorphous portion, and is used as a recording layer material for mark edge recording (Japanese Patent Laid-Open No. Hei 3).
No. 231889, Japanese Unexamined Patent Publication No. 4-191089, Japanese Unexamined Patent Publication No. 4-232779, and Japanese Unexamined Patent Publication No. 4-267.
192, JP-A-5-345478, JP-A-6-166266, etc.). Further, a recording material containing Sb-Te as a main component and Ag, In, Ga, Si or the like added thereto and having a single γ layer is disclosed (Japanese Patent Laid-Open No. 1-303643). .

I is a group I element, III is a group III element, and V
Is a group V element and VI is a group VI element, and I · (III _1-γ V
A recording layer represented by a general composition formula of _γ ) · VI type has also been proposed (JP-A-3-231889). However, these recording layers have a problem in repeated recording characteristics.

Disclosed in Japanese Patent Laid-Open No. 4-191089
When the recording layer used in the optical information recording medium is
Improves erase ratio and achieves high-speed recording, but repeats
There was a problem with the recording characteristics. Furthermore, JP-A-4-2327
Used in the optical information recording medium disclosed in Japanese Patent Publication No. 79
The structure of the recording part (crystallized part) of only the recording layer is stable.
Layer (AgSbTe _Two) And the
It is a mixture of Morpheus phases. others
Therefore, the repetitive recording characteristics are improved, but the crystallization part is fine.
Since there are various grain boundaries, it may cause noise.
Has become. This is because the recording / reproducing wavelength is about 780 nm.
CD-RW (Compact Disk-Rewrita) that uses laser light
optical information recording having a relatively low recording density such as
Although it does not have a serious adverse effect on the recording characteristics of the recording medium,
Laser light of 680 nm or less is used, and the recording density is CD-
DVD (Digital Versatile Disk) which is about 4 times as large as RW
RAM and high-density storage such as high-density DVD-RW
It was an obstacle to realizing the recording. In addition,
It also leaves a problem with the return recording characteristics.
It was

The structure of the crystallized portion of the recording layer used in Japanese Unexamined Patent Publication No. 4-267192 has a mixed phase of AgSbTe ₂ phase-separated from a uniform amorphous phase and another phase (stable layer or amorphous phase). It is in a state. When the other phase is an amorphous phase, the above-mentioned Japanese Patent Laid-Open No.
There is a problem similar to the case of the optical information recording medium disclosed in Japanese Patent Laid-Open No. 232779/1990, and when the other phase is a stable crystal phase, good recording characteristics cannot be obtained as described later. There is.

Further, in the optical information recording medium disclosed in Japanese Patent Laid-Open No. 1-303643, a single γ layer is obtained, and good repeating characteristics are obtained. What kind of γ layer does this have? No mention is made as to whether or not it has a crystal structure, and there is a problem in realizing a recording medium compatible with high linear velocity and high density in the future.

[0008]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned conventional problems, to cope with high linear velocity and high density, and to provide an optical information recording medium excellent in repeatability and storage characteristics. It is an object to provide (hereinafter, may be simply referred to as a recording medium).

[0009]

In order to solve the above problems, the present inventors have focused their attention on the materials constituting the recording layer and the reflection / heat dissipation layer, and as a result of earnest studies, as a result, the recording material was Ga.
, Sb and B, and Ag, Cu, Ge, S
n, Zn, In, Se, N, Ni, Ti, V, Cr, M
At least one element selected from n and Co is added, and the material for the reflective heat dissipation layer contains Ag as a main component, and In, Mg, C, Cu, Ni, Pd, Mo
It was found that the above problem can be solved when at least one element selected from the above is added, and the present invention has been completed based on this finding.

That is, the above-mentioned problem is (1) of the present invention, which has a layer structure including at least a first heat-resistant protective layer, a recording layer, a second heat-resistant protective layer, a reflective heat-dissipating layer, and an environmental protective layer on a substrate. , Recording and reproducing information by irradiating electromagnetic waves,
In a phase change type optical recording medium for erasing, this recording layer is composed of Ga, Sb and B, and Ag, Cu,
Ge, Sn, Zn, In, Se, N, Ni, Ti, V,
An optical recording medium comprising an alloy obtained by adding at least one element selected from Cr, Mn, and Co., (2) "The composition formula of the alloy constituting the recording layer is

[0011]

## EQU7 ## GaαSbβBγMδ (where M is Ag, Cu, Ge, Sn, Zn, In, S
at least one element selected from e, N, Ni, Ti, V, Cr, Mn, and Co, and α + β + γ + δ = 100
%, And α, β, γ, δ is 7 ≦ α
≦ 60, 30 ≦ β ≦ 90, 0 <γ ≦ 10, 0 <δ ≦ 15
(3) "The reflective heat dissipation layer contains Ag as a main component, and In, Mg, C, Cu, Ni, Pd, Mo
(4) The optical recording medium according to item (1) above, which comprises an alloy obtained by adding at least one element selected from
It consists of g, Cu and Ni, and its composition formula is

[0012]

## EQU8 ## Represented by AgxCuyNiz (where x + y + z = 100 atom%), x,
y and z are in the range of 95≤x≤98, 1≤y≤3, 1≤z≤2, and (5) "the reflection The alloy of the heat dissipation layer is Ag and Pd
And Mo, whose composition formula is

[0013]

## EQU9 ## Represented by AgxPdyMoz (where x + y + z = 100 atom%), x,
The optical recording medium according to item (3) above, wherein y and z are in the range of 94 ≦ x ≦ 98, 1 ≦ y ≦ 3, and 1 ≦ z ≦ 3 ”, (6)“ the reflection ” The alloy of the heat dissipation layer is Ag and In
And Mo, whose composition formula is

[0014]

## EQU10 ## Represented by AgxInyMoz (where x + y + z = 100 atom%), x,
The optical recording medium according to item (3), wherein y and z are in the range of 95 ≦ x ≦ 98, 1 ≦ y ≦ 2, and 1 ≦ z ≦ 3 ”, (7)“ the reflection ” The alloy of the heat dissipation layer is Ag and Mg
And Ni, whose composition formula is

[0015]

## EQU11 ## Represented by AgxMgyNiz (where x + y + z = 100 atom%), x,
y and z are 95 ≦ x ≦ 98, 0.5 ≦ y ≦ 2, 1 ≦ z ≦ 3
The optical recording medium according to item (3), characterized in that it is in the range of (3), (8) "the alloy of the reflective heat dissipation layer is composed of Ag, C and Cu

[0016]

## EQU12 ## Represented by AgxCyCuz (where x + y + z = 100 atom%), x,
The optical recording medium according to item (3) above, wherein y and z are in the range of 96 ≦ x ≦ 98, 0 ≦ y ≦ 1, 1 ≦ z ≦ 3 ”.

The present invention will be described in detail below. An object of the present invention is to provide a phase change type optical recording medium which is excellent in repetitive characteristics and storage characteristics capable of overwriting at a high linear velocity of 20 m / s or more. A recording material containing Ga, Sb, and B as main components, which can be crystallized at a higher speed than the recording material used in the technology, is used. As a recording material composed of Ga and Sb, the compound composition GaSb is reported as a phase change material capable of high-speed crystallization (Applied Optics / Vol.26, No.22 / 15 November 19
87 P4772-4776). It is unclear why this point makes high-speed crystallization impossible, but one idea is that Ga
It is considered that Sb has weak covalent bondability. On the other hand, a high crystallization rate causes a problem in the stability of the recording mark as an amorphous state. Therefore, in the present invention, B is added to solve the problem. That is, by adding B,
By controlling the crystallization rate of GaSb and maintaining the function of high-speed crystallization, the stability of amorphous recording marks was realized. Furthermore, in the present invention, Ag, Cu, Ge, Sn, Zn, In, S are used to improve the repetitive characteristics and the characteristics of the reproduced signal.
At least one element selected from e, N, Ni, Ti, V, Cr, Mn, and Co is added. The composition at this time is expressed by the composition formula

[0018]

## EQU13 ## GaαSbβBγMδ where M is Ag, Cu, Ge, Sn, Zn, In, S
at least one element selected from e, N, Ni, Ti, V, Cr, Mn, and Co, and α + β + γ + δ = 100
In atomic%, α, β, γ, δ are 7 ≦ α ≦ 60, 30 ≦ β
≦ 90, 0 <γ ≦ 10, 0 <δ ≦ 15, and α
Is less than 7, the crystallization rate is reduced and it becomes difficult to cope with high linear velocity. Further, when α is less than 60, the repeatability is deteriorated. If β is less than 30, the crystallization rate will decrease,
It becomes difficult to cope with high linear velocity, and if β is more than 90, it becomes difficult to amorphize and recording becomes impossible. Also, γ
In this case, if B is added even in a small amount, the stability of the recording mark is ensured and a good jitter of the reproduced signal can be obtained. However, it is desirable that the content is more than 1 at%, but more preferably 2 at%. . However, when it is more than 10, the crystallization rate is lowered and it becomes difficult to cope with high linear velocity. On the other hand, δ
In this case, if any of these elements is added, it is effective in improving the overwrite repetition characteristics and reproduction signal characteristics, but addition of 1 at% or more is preferable. On the other hand, if it is more than 15, the crystallization rate is lowered and it becomes difficult to cope with high linear velocity.

Further, in the present invention, an Ag alloy is used for the reflection / heat dissipation layer. The reason is that Ag having a good thermal conductivity is used to record a clean mark even at a high linear velocity, and In, Mg, C and C are used to improve the corrosion resistance.
At least one element selected from u, Ni, Pd, and Mo is added. Among them, Ag-Cu-
Ni alloys, Ag-Pd-Mo alloys, Ag-In-Mo alloys, Ag-Mg-Ni alloys, Ag-C-Cu alloys are preferable. Although the composition of the above alloy is limited in claims 5, 6, 7 and 8, In, Mg, C, Cu, Ni, Pd
In the case of the element of A, if it is less than the limited composition range, A
Corrosion resistance as a g-alloy decreases, and if it is large, the thermal conductivity becomes small, and the reproduction signal characteristics of the recording mark, particularly the jitter, deteriorates.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the structure of the recording medium of the present invention will be described with reference to the drawings. FIG. 1 shows an example of the structure of a recording medium of the present invention, in which a lower heat-resistant protective layer (2), a recording layer (3), an upper heat-resistant protective layer (4), a reflective heat dissipation layer (5) are provided on a substrate (1). ) Is provided. The heat-resistant protective layer does not necessarily have to be provided on both sides of the recording layer, but when the substrate (1) is made of a material having low heat resistance such as polycarbonate resin, it is desirable to provide the lower heat-resistant layer.

The material of the substrate (1) is usually glass, ceramic or resin, and a resin substrate is preferable from the viewpoint of moldability and cost. Typical examples of the resin include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polystyrene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, urethane resin, etc. Polycarbonate resin is preferable from the viewpoints of properties and optical characteristics. The substrate may have a disc shape, a card shape, or a sheet shape.

The heat-resistant protective layer, that is, the dielectric layer, is made of (Zn
A film is formed by a sputtering method using S). (SiO ₂ ). Since this dielectric layer has a function as a heat-resistant protective layer and a function as an optical interference layer, it is necessary to make the most of these functions. For that purpose, the film thickness is 200 to 3000 Å, Preferably 350-200
Set to 0Å. When it is less than 200Å, the function as heat resistance is lost, and when it exceeds 3000Å, interfacial peeling is likely to occur, which is not preferable.

The recording layer of the present invention is generally formed by a sputtering method, and the film thickness is 100 to 100.
It is 1000Å, preferably 200 to 350Å. 1
If it is thinner than 00Å, the light absorption ability is lowered and the function as a recording layer is lost. An Ag alloy is used for the reflection and heat dissipation layer of the present invention, and its film can be formed by a sputtering method. The film thickness is 500-2000
Å, preferably 700 to 1500Å.

[0024]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Track pitch 0.7 μm, groove depth 400
Å, a lower heat-resistant protective layer, a recording layer, an upper heat-resistant protective layer, and a reflective heat dissipation layer were formed by a sputtering method on a polycarbonate substrate having a thickness of 0.6 mm and a diameter of 120 mmφ in order to produce a recording medium having the structure shown in Table 1. It was set up sequentially. Further, an environmental protection layer was provided on the reflection / heat dissipation layer by spin coating. Next, after initial crystallization of the obtained recording medium, the recording linear velocity and recording power were set to 20 m / s (18 mw) and 23 m.
/ S (20 mw) and 25 m / s (22 mw). The wavelength of the recording laser at this time is 650 nm, and the EFM
Repeat the overwrite with a random pattern,
The signal characteristic is evaluated by the jitter value of the 3T signal,
The storage characteristics were evaluated by the 3T signal jitter value of the initial recording (first overwrite) after holding the recording medium overwritten 3000 times at 80 ° C. under 85% humidity for 300 hours. The results are shown in Tables 2 and 3.

[0026]

[Table 1-1]

[0027]

[Table 1-2]

[0028]

[Table 2-1] Note) The recording medium after overwriting 3000 times, at 80 ℃, 8
Overwrite 1 after holding at 5% humidity for 300 hours
The jitter value of the third 3T signal was evaluated.

[0029]

[Table 2-2] Note) The recording medium after overwriting 3000 times, at 80 ℃, 8
Overwrite 1 after holding at 5% humidity for 300 hours
The jitter value of the third 3T signal was evaluated.

[0030]

[Table 3-1] Note) The recording medium after overwriting 3000 times, at 80 ℃, 8
Overwrite 1 after holding at 5% humidity for 300 hours
The jitter value of the third 3T signal was evaluated.

[0031]

[Table 3-2] Note) The recording medium after overwriting 3000 times, at 80 ℃, 8
Overwrite 1 after holding at 5% humidity for 300 hours
The jitter value of the third 3T signal was evaluated.

As is clear from Tables 2 and 3, the recording mediums (Examples 1 to 14) constituted by using the recording material and the reflection / heat dissipation material of the present invention were 20 m / s, 23 m / s, 25.
It can be seen that at a linear velocity of m / s, the repeating characteristics of jitter and overwrite are good, and the storage characteristics are also excellent. As comparative examples, the recording materials are Ga ₁₂ Sb ₈₈ , Ga ₅₀ Sb _50.
When Comparative Example 1 and 2 are used, the recording can be performed at a high linear velocity, but the jitter which is influenced by the overwrite repetitive characteristic and the stability of the recording mark is bad. Further, in Comparative Examples 3 and 4 in which the reflective heat dissipation layer material was Ag using the recording material of the present invention, the jitter and overwrite repetition characteristics were good, but the storage resistance was poor due to the poor weather resistance of Ag. It shows that it does not have.

[0033]

As is apparent from the detailed and specific description above, the present invention can cope with a high linear velocity of 20 m / s or more, and is a phase change type optical information recording medium excellent in repeatability and storage characteristics. Is provided, which has an extremely excellent effect of contributing to the field of optical information recording.

[Brief description of drawings]

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

[Explanation of symbols]

1 substrate 2 Lower heat-resistant protective layer 3 recording layers 4 Lower heat-resistant protective layer 5 Reflective heat dissipation layer

Continued front page    (72) Inventor Hiroko Tashiro             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Mizutani Mirai             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Koji Deguchi             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F-term (reference) 2H111 EA03 EA04 EA12 EA23 EA32                       EA40 EA41 FA12 FA14 FA18                       FA23 FB04 FB05 FB06 FB08                       FB09 FB15 FB16 FB17 FB19                       FB20 FB21 FB23 FB29 FB30                 5D029 JA01 MA13

Claims (8)

[Claims] 1. A layer structure comprising at least a first heat-resistant protective layer, a recording layer, a second heat-resistant protective layer, a reflective heat-dissipating layer, and an environmental protective layer on a substrate, and irradiating with an electromagnetic wave,
In a phase change type optical recording medium for recording, reproducing and erasing information, this recording layer is composed of Ga, Sb and B,
Ag, Cu, Ge, Sn, Zn, In, Se,
An optical recording medium comprising an alloy obtained by adding at least one element selected from N, Ni, Ti, V, Cr, Mn and Co. 2. The composition formula of the alloy forming the recording layer is as follows: GaαSbβBγMδ (where M is Ag, Cu, Ge, Sn, Zn, In, S
at least one element selected from e, N, Ni, Ti, V, Cr, Mn, and Co, and α + β + γ + δ = 100
%, And α, β, γ, δ is 7 ≦ α
≦ 60, 30 ≦ β ≦ 90, 0 <γ ≦ 10, 0 <δ ≦ 15
The optical recording medium according to claim 1, wherein the optical recording medium is in the range of 1. 3. The reflection heat dissipation layer is made of an alloy containing Ag as a main component and at least one element selected from In, Mg, C, Cu, Ni, Pd, and Mo added thereto. The optical recording medium according to claim 1, wherein: 4. The alloy of the reflection and heat dissipation layer is Ag, Cu and N.
The composition formula is represented by AgxCuyNiz (where x + y + z = 100 atomic%), and x,
The optical recording medium according to claim 3, wherein y and z are in the range of 95≤x≤98, 1≤y≤3, and 1≤z≤2. 5. The alloy of the reflection and heat dissipation layer is Ag, Pd and M.
and the composition formula is represented by AgxPdyMoz (where x + y + z = 100 atomic%), and x,
The optical recording medium according to claim 3, wherein y and z are in the range of 94≤x≤98, 1≤y≤3, and 1≤z≤3. 6. The alloy of the reflection and heat dissipation layer is Ag, In and M.
The composition formula is represented by AgxInyMoz (where x + y + z = 100 atomic%), and x,
The optical recording medium according to claim 3, wherein y and z are in the range of 95≤x≤98, 1≤y≤2, and 1≤z≤3. 7. The alloy of the reflection and heat dissipation layer is Ag, Mg and N.
i, the composition formula of which is represented by AgxMgyNiz (where x + y + z = 100 atom%), and x,
y and z are 95 ≦ x ≦ 98, 0.5 ≦ y ≦ 2, 1 ≦ z ≦ 3
The optical recording medium according to claim 3, wherein the optical recording medium is in the range of. 8. The alloy of the reflection and heat dissipation layer is Ag, C and Cu.
And its composition formula is represented by AgxCyCuz (where x + y + z = 100 atom%), and x,
The optical recording medium according to claim 3, wherein y and z are in the range of 96≤x≤98, 0≤y≤1, and 1≤z≤3.