JP3510551B2 - Optical recording medium - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical recording medium for recording information by changing the optical characteristics of a recording layer by applying external energy. More particularly, it relates to an optical recording medium that can be used for a write-once compact disc (CD-R), a DVD-R and the like.

[0002]

2. Description of the Related Art An optical recording medium used in a CD-R or the like records information by applying external energy to change the optical characteristics of a recording layer. Therefore, the optical characteristics such as reflectance of the recording layer are easily changed during recording, that is, the recording characteristics are excellent, and the optical characteristics of the recording layer are difficult to change during non-recording, that is, the durability is excellent. And both are required.

That is, in an optical recording medium, at the time of recording when external energy is applied, the recording layer is physically and / or physically
Alternatively, it is necessary to chemically react to change the optical characteristics such as reflectance. In the non-recording state, it is necessary to maintain the optical characteristics as they are without causing a reaction in the recording layer. Therefore, from the viewpoint of recording characteristics and durability, a recording layer in which a physical and / or chemical reaction occurs during recording to change optical characteristics, and no reaction occurs during non-recording, and optical characteristics do not change Development has been carried out on the materials and composition of the.

For example, Japanese Patent Publication No. 6-78033 discloses S.
An optical recording medium using an n-Bi alloy layer and a thin film of Ge, Cr, Ti, Ni or the like laminated on the Sn-Bi alloy layer has been proposed. By using a Sn-Bi alloy layer as the recording layer, recording characteristics and oxidation resistance are improved, and by further laminating a metal or semimetal layer (thin film) made of Ge or the like on the Sn-Bi alloy layer, This is a method for improving the oxidation resistance. That is, Japanese Patent Examination 6-7
The invention described in Japanese Patent No. 8033 has Sn-B in the recording layer.
The use of the i alloy layer facilitates the change of the optical characteristics during recording and suppresses the change of the optical characteristics due to oxidation or the like during non-recording, and further stacks a thin film such as Ge on the Sn—Bi alloy layer. This further suppresses changes in optical characteristics due to oxidation or the like during non-recording.

[0005]

As a result of research, the present inventor has recognized that the use of a Sn-Bi alloy as a recording layer is effective in improving recording characteristics as follows.

[0006] The words Sn-Bi alloy when deposited on a substrate, but Sn-Bi alloy recrystallizes on the substrate surface, suppressed to a certain extent the grain growth of the particles because it is metal KyoAkirasei The layer is formed by increasing the number of particles rather than growing the particles. As a result, the shape of the recording layer becomes regular. This lowers the noise level of the optical medium, resulting in C / N (carrier to noise).
Tio, that is, the characteristic deterioration of the carrier / noise output level) is suppressed, and excellent characteristics can be provided.

The melting point of Sn is about 232 ° C.
The melting point of the n-Bi alloy is about 139 ° C. Therefore, at the time of recording due to incidence of laser light or the like, the Sn—Bi alloy layer is easily melted and its optical characteristics are easily changed. In addition, Sn, which has high reactivity, tends to become a liquid phase.
It becomes easy to react with other layers close to the Bi alloy layer, and a high degree of modulation can be obtained. Here, the degree of modulation is the percentage of the value obtained by subtracting the reflectance (B) after recording from the reflectance (A) before recording to the reflectance before recording. That is (A-B) / A
Is a value obtained by multiplying the value of by 100%.

Further, when a Sn-Bi alloy is formed as a recording layer, the Sn-Bi alloy is a eutectic metal and has a low melting point of about 139 ° C., so that this layer contains Sn or Sn containing a large amount of Sn component. A fine region P of -Bi and a fine region Q of Sn-Bi having a large amount of Bi or Bi components are formed of at least two phases. In this case, since the area P has high reactivity and the area Q has low reactivity, the recording layer is Sn-B.
When the i-alloy layer and another layer stacked in proximity to Sn-Bi are used, the reaction between the Sn-Bi alloy and another layer in proximity to the film formation is suppressed by the existence of the region Q. be able to.

Therefore, the present inventor has heretofore used a Sn-- recording layer.
An optical recording medium consisting of a Bi alloy layer and an oxide material layer such as WO ₃ (International Application No. PCT / JP98 / 04675,
International publication number WO99 / 20472) and recording layer is S
An optical recording medium having an n-Bi alloy layer and a GeSx (1 <x ≦ 2) layer has been developed.

However, even if the recording characteristics are improved when the Sn--Bi alloy is used as at least one of the recording layers as described above, there is a problem in the durability of the optical recording medium, particularly in the high temperature and high humidity environment.

On the other hand, in the invention described in Japanese Patent Publication No. 6-78033, Sn-Bi is used to record information by changing the optical characteristics by applying external energy.
The alloy layer plays a role, and in order to improve durability, a thin film of Ge or the like must be further laminated after forming this Sn—Bi alloy layer, which causes a problem that the manufacturing cost rises accordingly. is there. Therefore, even if the Sn-Bi alloy is used as the recording layer, a new structure is required.

Therefore, an object of the present invention is to provide excellent recording characteristics,
Another object of the present invention is to provide an optical recording medium having excellent durability, especially durability in a high temperature and high humidity environment.

[0013]

Therefore, as a result of earnest research, the present inventor has an optical recording medium that has a recording layer and changes the optical characteristics of the recording layer by applying external energy to record information. In this recording layer, Sn and Bi
An optical recording medium is characterized by having at least a first layer containing an oxidizable substance that is more easily oxidized than Sn and Bi.

The optical recording medium of the present invention has a recording layer, and by applying light or an electromagnetic wave to the recording layer, the optical characteristics of the recording layer are changed to record information. In the write-once type optical recording medium which does not change, the recording layer contains at least Sn, Bi, Ge and Ga.
Also has at least a first layer containing an oxidizable substance that is more easily oxidized than Sn and Bi. That optical recording medium of the present invention, the oxidizable substance which is easily oxidized than Sn and Bi excellent Sn-Bi alloy in the recording characteristics, i.e. more on the addition of at least one <br/> of Ge and Ga, Improvement in durability is achieved by modifying the Sn-Bi alloy itself. That is, by adding Sn and Bi and an oxidizable substance that is more easily oxidized than Sn and Bi, the oxidizable substance is added to S
It is oxidized before n and Bi and can suppress the corrosion of the Sn-Bi alloy due to the oxidation and the like, and the oxide film formed by the oxidation of the substance to be oxidized is formed on the surface of the Sn-Bi alloy. When formed, the corrosion of the Sn-Bi alloy due to oxidation or the like can be delayed. As a result , it is possible to prevent deterioration of the recording layer with time during non-recording,
The durability of the optical recording medium can be remarkably improved.

Also, the Sn and Bi of the first layer are combined.
The composition of Bi is 30 to 70 original when it is 100 atomic%
When the total content of the first layer is 100 atom%, and when Ga is used as the oxidizable substance,
The composition of a is 0.05 to 30 atomic%, the oxidizable compound
When Ge is used as the quality, the composition of Ge is 0.01 to
It is preferably 2 atomic%. If there is too much oxide,
This will deteriorate the recording characteristics of the optical recording medium.

In the optical recording medium of the present invention, the recording layer is Sn.
Since at least the first layer containing Bi and Bi and an oxidizable substance that is more easily oxidized than Sn and Bi is included, the recording characteristics of the recording layer can be improved. That is, the recording layer is Sn and B
As long as the first layer containing i and the oxidizable substance that is more easily oxidized than Sn and Bi is included, another layer can be included.

As described above, the Sn-Bi alloy used for the first layer of the recording layer recrystallizes on the substrate surface during film formation, but since it is a eutectic metal, its grain growth. Is suppressed to some extent, and a layer is formed by increasing the number of particles rather than growing the particles. As a result, the shape of the recording layer becomes regular. Therefore, by using a first layer containing Sn and Bi and an oxidizable substance that is more easily oxidized than Sn and Bi for the recording layer, the noise level of the optical recording medium remains low and the deterioration of the C / N characteristics is suppressed. be able to.

Further, since the melting point of the Sn-Bi alloy is about 139 ° C., when recording by incidence of laser light, etc.,
Since the first layer containing the Sn-Bi alloy is easily melted, the optical characteristics are likely to be changed, and the first layer containing the Sn-Bi alloy is likely to react with other layers, and a high degree of modulation can be obtained. .

Further, the Sn-Bi alloy is composed of at least two phases, that is, a fine region P of Sn or Bi containing a large amount of Sn or Sn and a fine region Q of Sn or Bi containing a large amount of Bi or Bi. To be done. In this case, since the area P has high reactivity and the area Q has low reactivity, the recording layer is Sn-B.
When it is composed of a first layer containing an i alloy and another layer stacked in proximity to Sn-Bi, a reaction during film formation between the first layer containing an Sn-Bi alloy and another layer in proximity Area Q
Can be suppressed by the presence of.

In this case, the recording layer is adjacent to the first layer and a substance having at least one of S, Se and Te as constituent elements, or W, Mo, Rh, Ag, Ti, As, Ge, S
It is also possible to have a second layer containing a substance containing at least one element of e and Ce and having oxygen as a component, and reacting with the first layer by applying light or electromagnetic waves. By the reaction between the first layer and the second layer,
The optical properties of the recording layer can make a remarkable change.

That is, when the second layer contains a substance containing at least one of S, Se and Te as a constituent element, the first layer melts and becomes reactive when recording by incidence of laser light or the like. Since high Sn is in the liquid phase, the Sn contained in the first layer
Reacts with a substance containing at least one of S, Se, and Te contained in the second layer to form a sulfide (Sn
S, SnS ₂ ), selenide (SnSe, SnSe ₂ ),
It is considered that a telluride (SnTe) or the like is formed, and a high degree of modulation can be obtained and excellent recording characteristics can be obtained.

When the second layer contains a substance containing oxygen as a constituent, the first layer is melted at the time of recording by incidence of laser light or the like, and Sn and / or Bi contained in the first layer is melted. It is considered that redox reaction occurs between the substance contained in the second layer and oxygen as a constituent element, and all or part of Sn and / or Bi is changed to an oxide, and a high degree of modulation may be obtained. It is possible to have excellent recording characteristics.

Further, this recording layer can be composed of only the first layer containing Sn and Bi, and an oxidizable substance which is more easily oxidized than Sn and Bi. Since the first layer contains an oxidizable substance that is more easily oxidized than Sn, the durability of the optical recording medium can be improved. In addition, the manufacturing cost can be reduced as compared with a structure in which a thin film of Ge or the like is laminated on the Sn-Bi alloy layer.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The optical recording medium of the present invention records information by physically and / or chemically changing the optical characteristics of the recording layer by irradiating, for example, a recording laser beam as external energy. It is an optical recording medium. This optical recording medium can be used for, for example, optical discs such as CD-R and DVD-R on which music and data are recorded.

(First Embodiment) The optical recording medium of the present embodiment has a recording layer, and by applying external energy, the optical characteristics of this recording layer are changed to record information. In the medium, this recording layer is composed of Sn and Bi.
And an oxidizable substance that is more easily oxidized than Sn and Bi. The present embodiment will be described below.

The optical recording medium of this embodiment can be constructed by laminating a substrate, a recording layer and a protective layer.

The substrate serves as a recording layer and a protective layer, and is made of a transparent material capable of transmitting irradiation light for recording, reproduction and the like. Therefore, the material of the substrate can be selected depending on the irradiation light. Laser light is usually used as the irradiation light. In that case, a material that can transmit laser light may be selected. A transparent resin such as polycarbonate, polyethylene terephthalate (PET), or acrylic can be used as the material. These resins are excellent in that they are lightweight. Alternatively, transparent glass may be used. Glass is excellent in that it has high mechanical strength.

The shape of the substrate may be selected according to the application of the optical recording medium. In particular, with respect to the thickness, it is preferable to obtain the mechanical strength required by the optical recording medium.

A track (guide groove) for guiding laser light can be formed on the surface of the substrate on which the recording layers are laminated. The track may be formed in an appropriate shape according to the shape of the optical storage medium, the application, and the like. In the case of a disc-shaped optical recording medium, the track may be formed in a concentric shape or a spiral shape.

The recording layer is a layer in which information is recorded by changing its optical characteristics. Information is recorded by changing the optical characteristics of the recording layer. The recording layers of the present embodiment are Sn and Bi.
And a layer containing an oxidizable substance that is more easily oxidized than Sn and Bi, that is, only the first layer.

Since the first layer contains the Sn-Bi alloy, the noise level of the optical recording medium can be lowered and the deterioration of the C / N characteristics can be suppressed as described above. Also S
Since the melting point of the n-Bi alloy is approximately 139 ° C., the first layer containing the Sn-Bi alloy is easily melted at the time of recording by incidence of a laser beam or the like, so that the optical characteristics are easily changed and the degree of modulation is excellent. ing. Therefore, the optical recording medium of the present embodiment can improve the recording characteristics of the recording layer.

The optical recording medium of the present embodiment is Sn-
Since than Sn and Bi to the Bi alloy with addition of oxidizable substance susceptible to oxidation, Sn-Bi alloys thereof even for reforming the can improve the oxidation resistance of the Sn-Bi alloy. That is, by adding an oxidizable substance that is more easily oxidized than Sn and Bi to the Sn-Bi alloy, this oxidizable substance is oxidized before Sn and Bi, and corrosion of the Sn-Bi alloy due to oxidation or the like is suppressed. be able to. Further, an oxide film formed by the oxidation of the substance to be oxidized is formed on the surface of the Sn-Bi alloy, and corrosion due to oxidation or the like can be further delayed. As a result, deterioration of the recording layer with time during non-recording can be prevented, and the durability of the optical recording medium can be significantly improved.

As the substance to be easily oxidized, Ge,
Ga or the like can be used. This is because Ge, Ga and the like are more easily oxidized than Sn and Bi, so that the oxidation resistance of the recording layer is improved and the recording or reproducing characteristics are not adversely affected.

The ratio of the substance to be oxidized which is more easily oxidized than Sn and Bi needs to be set to an appropriate amount. That is, if the amount of the substance to be oxidized is too small, the above-mentioned excellent durability cannot be exhibited. On the contrary, if the amount of the oxidizable substance is too large, the characteristics of the Sn-Bi alloy, which is the mother alloy, are increased by adding the oxidizable substance
In particular, it has a great influence on the melting point, the crystal grain size at the time of film formation, etc., and deteriorates the recording characteristics of the optical recording medium. For example, when Ga is added to the Sn-Bi alloy, a large addition amount causes a significant decrease in the melting point, which leads to a decrease in C / N characteristics, making it substantially unusable as a recording medium. On the other hand, in the case of adding Ge, if the addition amount is large, the melting point is remarkably increased,
After that, it causes an increase in recording power, a decrease in reflectance, and the like, so that it cannot be practically used as an optical recording medium.

Therefore, when a Sn-Bi alloy having a Bi composition of 30 to 70 atomic% is used as a mother alloy, the Ga addition amount is preferably 0.05 to 30 atomic% with all the components being 100 atomic%. The amount of Ge added is 100 atomic% for all components.
Is preferably 0.01 to 2 atomic%. When Ge is added, it is sufficient that the mother alloy contains the above components.
A metal containing a large amount of e or Ge may be phase-separated and may be present in the grain boundary layer or grain boundary of the Sn—Bi alloy or the metal particles containing Sn, Bi as the main component.

The thickness of the recording layer composed of only the first layer is not particularly limited, and can be set to an appropriate thickness. Generally, it may be about 20 to 60 nm.

The recording layer can be formed by a known method such as a sputtering method or a vacuum evaporation method.

The protective layer is a layer for protecting the recording layer. For example, the protective layer can be formed using an ultraviolet curable resin by a spin coating method.

(Second Embodiment) The optical recording medium of the present embodiment has a recording layer, and by applying external energy, the optical characteristics of this recording layer are changed to record information. In the medium, this recording layer is composed of Sn and Bi.
And a first layer containing an oxidizable substance that is more easily oxidized than Sn and Bi, and S, Se, T
An optical recording medium comprising a substance having at least one of e as a constituent element and having a second layer which reacts with the first layer by applying external energy. The present embodiment will be described below.

The optical recording medium of this embodiment can be constructed by laminating a substrate, a recording layer and a protective layer. Unlike the first embodiment, the recording layer of the present embodiment has a first layer and a second layer that react with each other by applying external energy. As in the case of the first embodiment, the first layer is a layer containing Sn and Bi and an oxidizable substance that is more easily oxidized than Sn and Bi, and the second layer is the first layer. And a layer containing a substance having at least one kind of S, Se, and Te as a constituent element. That is, it differs from the first embodiment in that the first layer and the second layer of the recording layer react with each other by application of external energy. The following description will focus on the parts that are different from the first embodiment.

As the substrate, the same substrate as the substrate of the first embodiment can be used. Therefore, the description in the first embodiment is appropriate.

The recording layer of the present embodiment comprises a first layer and a first layer which react with each other by applying external energy.
A second layer adjacent to the layer.

The first layer is a layer containing Sn and Bi and an oxidizable substance that is more easily oxidized than Sn and Bi, and the same layer as in the first embodiment can be used. . Therefore, the description of the first embodiment basically applies. As in the case of the first embodiment, Ge, Ga, or the like can be used as the substance to be oxidized. Also, Ge
The amount of Ga and / or Ga added may be the same as in the case of the first embodiment. Therefore , the description in the first embodiment is appropriate.

The second layer of the present embodiment is a layer containing a substance having at least one of S, Se and Te as a constituent element. The second layer has a substance containing a chalcogen element such as so-called S, Se or Te, for example, GeSx (1 <
x ≦ 2), Y ₅ S ₇ , La ₂ O ₂ S ₂ , Ce ₂ O ₂ S ₂ , GeS
ex (1 <x ≦ 2), SeS, ZnSe, ZnTe, P
bTe, TeI ₂ or the like can be used.

In the present embodiment, the Sn-Bi contained in the first layer due to the irradiation of the laser beam during recording or the like.
The alloy is melted to become almost a melt, and highly reactive Sn can directly react with a substance containing S, Se, Te or the like as a constituent element. Since Sn is in the liquid phase, Sn
Reacts with a substance containing at least one of S, Se, and Te as a constituent element, and becomes a reaction between a liquid phase and a solid phase having higher reactivity than a reaction between solid phases, and chemically reacts with S, Se, Te, etc. It becomes easy to react, and sulfide (SnS, SnS ₂ ), selenide (SnSe, SnSe ₂ ), telluride (SnT)
e) etc. will be generated. As a result, the optical characteristics (reflectance, etc.) of the recording layer change, and information can be recorded. Since the recording layer has the first layer and the second layer that react with each other, the optical characteristics of the recording layer can be remarkably changed, a high degree of modulation can be obtained, and the recording characteristics can be remarkably improved. be able to.

Further, the Sn-Bi alloy is, as described above,
The presence of the minute regions Q of Bi or Sn-Bi having a low reactivity and having a large amount of Bi components causes the first layer and the second layer containing a substance having at least one of S, Se and Te as a constituent element.
The reaction with the layer during non-recording can be suppressed.

Between the first layer and the second layer, Zn
S, Si, Ge, SiO ₂ , GeO ₂ , SiNx (1 <x
A third layer containing <1.5), GeNx (1 <x <1.5), C, hydrocarbon, etc. can be laminated. By interposing the third layer between the first layer and the third layer, the reaction between the first layer and the second layer during non-recording can be further suppressed, and the deterioration of the recording characteristics can be more efficiently performed. Can be suppressed.

The thickness of these recording layers is not particularly limited and can be set to an appropriate thickness. Since the recording layers are stacked in this embodiment, the thickness of the first layer may be approximately 10 to 100 nm, and the thickness of the second layer may be approximately 20 to 250 nm. The thickness of the third layer may be appropriately selected, but in order to sufficiently bring out the characteristics of the third layer as a layer for suppressing the reaction, it is 0.5 to 5 n.
m is preferred.

The recording layer can be formed by using a known method such as a sputtering method or a vacuum vapor deposition method as in the first embodiment.

The protective layer is a layer for protecting the recording layer. First
It may be carried out in the same manner as in the case of the first embodiment, and the same one as in the case of the first embodiment can be used. For example, the protective layer can be formed using an ultraviolet curable resin by a spin coating method.

(Third Embodiment) The optical recording medium of the present embodiment has a recording layer, and by applying external energy, the optical characteristics of the recording layer are changed to record information. In the medium, this recording layer is composed of Sn and Bi.
And a first layer containing an oxidizable substance that is more easily oxidized than Sn and Bi, and a substance that is close to the first layer and has oxygen as a constituent and that is supplied with external energy. An optical recording medium having one layer and a second layer that reacts. The present embodiment will be described below.

The optical recording medium of this embodiment can be constructed by laminating a substrate, a recording layer and a protective layer. The recording layer of the present embodiment has a first layer and a second layer that react with each other by applying external energy.
The layer is a layer containing Sn and Bi and an oxidizable substance that is more easily oxidized than Sn and Bi, and the second layer is a layer that is close to the first layer and contains a substance containing oxygen as a constituent element. .
That is, the second embodiment is different from the second embodiment in that the second layer of the recording layer is a layer containing a substance having oxygen as a constituent element. Hereinafter, description will be made focusing on parts different from the first embodiment and the second embodiment.

As the substrate, the same substrate as the substrate of the first embodiment can be used. Therefore, the description of the first embodiment is valid.

The recording layer of the present embodiment comprises a first layer and a first layer which react with each other by applying external energy.
It is similar to the second embodiment in that it has a layer and a second layer adjacent thereto.

The first layer is made of Sn and Bi, and Sn and B.
a layer containing an oxidizable substance that is more easily oxidized than i.
The same thing as the case of the first embodiment can be used. Therefore, the description of the first embodiment basically applies.

As in the case of the first embodiment, Ge, Ga or the like can be used as the substance to be oxidized. Also, G
The amount of e and / or Ga added may be the same as in the case of the first embodiment. Therefore , the description in the first embodiment is appropriate.

The second layer of this embodiment is a layer containing a substance having oxygen as a constituent element. The second layer contains W, Mo, R
A substance having oxygen as a constituent element such as an oxide containing at least one element of h, Ag, Ti, As, Ge, Se and Ce can be used. For example, WO ₃ , Mo
O ₃ , Rh ₂ O ₃ , TiO ₂ , As ₂ O ₃ , GeO ₂ , Se
O ₂ , oxides such as CeO ₂ , GeON, Ce (OH) ₄ ,
AgIO ₃ or the like can be used.

When the second layer contains a substance containing oxygen as a constituent element, the first layer is formed at the time of recording by incidence of laser light or the like.
The layer is melted and a redox reaction occurs between Sn and / or Bi contained in the first layer and a substance containing oxygen as a constituent element contained in the second layer, whereby all or one of Sn and / or Bi is contained. It is considered that the parts are changed to oxides such as SnO and Bi ₂ O ₃ . Since the recording layer has the first layer and the second layer that react with each other, the optical characteristics of the recording layer can be remarkably changed, a high degree of modulation can be obtained, and the recording characteristics can be remarkably improved. be able to.

Further, since the substance before or after the reaction contains a substance containing oxygen as a constituent element such as an oxide, it is resistant to heat and moisture and has excellent environmental resistance, and unnecessary reaction is caused even during non-recording. Easy to control.

The energy generated when Sn is combined with 1 mol of oxygen molecules (hereinafter referred to as oxygen bond energy) is approximately 610 kJ. Therefore, as a substance containing oxygen such as an oxide contained in the second layer as a constituent element,
It is preferable to use a substance containing oxygen, such as an oxide, which has an energy required to dissociate 1 mol of oxygen molecules (hereinafter referred to as oxygen dissociation energy) of 550 kJ or less. Since the oxygen bond energy of the first layer is larger than the oxygen dissociation energy of the second layer, the reaction between the first layer and the second layer becomes an exothermic reaction, and the reaction does not proceed in the opposite direction. Can be secured. Further, when the oxygen dissociation energy exceeds 550 kJ, oxygen becomes less dissociated and the reactivity is lowered. For example, MoO ₃ , R
h ₂ O ₃ , TiO ₂ , As ₂ O ₃ , SeO ₂ , CeO ₂ , WO ₃
Etc. are preferred.

As described above, all / or a part of Sn and / or Bi contained in the first layer and an oxide or the like such as WO ₃ contained in the second layer undergo redox reaction by irradiation with laser light or the like. As a result, Sn and / or Bi oxides are formed. Therefore, the optical characteristics (reflectance, etc.) of the recording layer change, and information can be recorded.

Between the first layer and the second layer, C (carbon), hydrocarbon, Si, Ge, SiNx (1 <
x <1.5), GeNx (1 <x <1.5), Ti,
A third layer containing W, Zr, etc. can be laminated. Third
By interposing a layer between the first and third layers,
The reaction between the first layer and the second layer during non-recording can be suppressed, and the deterioration of recording characteristics can be suppressed more efficiently.

The thickness of these recording layers is not particularly limited and can be set to an appropriate thickness. The thickness of the first layer may be approximately 10 to 100 nm, and the thickness of the second layer may be approximately 10 to 250 nm. The thickness of the third layer may be appropriately selected, but in order to sufficiently bring out the characteristics of the third layer as a layer for suppressing the reaction, it is 0.5 to 10
nm is preferred.

The recording layer can be formed by using a known method such as a sputtering method or a vacuum evaporation method, as in the first embodiment.

The protective layer is a layer for protecting the recording layer. First
This is similar to the case of the above embodiment, and the protective layer can be formed by using an ultraviolet curable resin by, for example, a spin coating method. (Other Embodiments) An optical recording medium according to an embodiment of the present invention is an optical recording medium which has a recording layer and changes the optical characteristics of the recording layer by applying external energy to record information. If this recording layer is an optical recording medium having at least a first layer containing Sn and Bi and an oxidizable substance that is more easily oxidized than Sn and Bi, the above-mentioned first, second and third implementations are possible. It is not limited to the form.

For example, the second layer of the recording layer may be laminated with a layer other than those described in the second embodiment and the third embodiment as long as it reacts with the first layer.

Further, Ag and A are added to the first layer containing Sn and Bi and the substance to be oxidized which is more easily oxidized than Sn and Bi.
It is also possible to add u, In, or the like.

The external energy that changes the optical characteristics of the recording layer is not particularly limited to laser light. It may be light in general, electromagnetic waves, or the like.

[0069]

EXAMPLES The optical recording medium of the present invention will be described below based on examples. Comparative examples are also described for comparison with the examples.

[Example 1] (Example 1) This example 1 is an optical recording which has a recording layer and changes the optical characteristics of the recording layer by applying laser light as external energy to record information. In the medium, this recording layer is an optical recording medium having only the first layer containing Sn, Bi and Ga. That is, the optical recording medium uses laser light as external energy and uses Ga as an oxidizable substance that is more easily oxidized than Sn and Bi. FIG. 1 shows a partial cross-sectional structure of the optical recording medium according to the first embodiment.

The optical recording medium 100 of the first embodiment has a disc shape as a whole. As shown in FIG.
The recording layer 20 and the protective layer (resin layer) 30 are laminated. The substrate 10 is made of transparent polycarbonate having a thickness of 1.2 mm and is formed in a disc shape. Laser light for recording and reproducing optical information enters from one surface 10a of the substrate as shown by an arrow A. One surface 10a of the substrate 10 on the laser light incident side is a smooth surface, and the other surface 10b is provided with a spiral track (guide groove) 10c for guiding the laser light.

On the other surface 10b of the substrate 10, a Sn-45 atom% Bi-10 atom% Ga film 21a is laminated as a recording layer 20. Furthermore, this Sn-45 atom% Bi-10
A protective layer (resin layer) 30 made of an ultraviolet curable resin is formed on the atomic% Ga film 21a to cover and protect the recording layer 20.

The optical recording medium of Example 1 was manufactured as follows.

First, the one surface 10a is a smooth surface and the other surface 10b.
A 1.2 mm-thick polycarbonate disk-shaped substrate 10 having a track 10c formed therein was prepared. On the other surface 10b on which the track 10c is formed, a Sn-45 atomic% Bi-10 atomic% Ga film 21a is formed by a DC sputtering method, a sputtering gas type: Ar, a sputtering gas pressure: 4
S under the film forming conditions of × 10 ⁻¹ Pa and input power: 250 W
A 40 nm film was formed using an n-45 atomic% Bi-10 atomic% Ga target.

Next, an ultraviolet curable resin is applied by a spin coating method, and the ultraviolet curable resin is cured by using a high pressure mercury lamp to form a protective layer (resin layer) 30, and the optical recording medium 100 of the first embodiment is formed. Was produced.

The recording characteristics of the optical recording medium 100 manufactured in Example 1 were confirmed.

Optical recording medium 1 manufactured by the above manufacturing method
00, laser light having a wavelength of 780 nm is condensed from the side of the one surface 10a onto the surface of the Sn-45 atomic% Bi-10 atomic% Ga film 21a through an objective lens having an NA (numerical aperture) of 0.5. , Recorded. Linear velocity is 5.6m / se
c, the recording frequency was 800 kHz, and the recording laser waveform was a rectangular wave with a duty ratio of 50%. At this time, the characteristics of the optical recording medium were such that the unrecorded portion reflectance was 47%, the recording laser power was 16 mW, the C / N was 53 dB, and the modulation was 86%.

The recorded optical recording medium 100 was held for 120 hours in an environment of a temperature of 60 ° C. and a relative humidity of 90% as an environment resistance test. After this, C / N, reflectance of unrecorded area,
When the degree of modulation was measured, it was confirmed that no change was observed in any of the characteristics within the measurement error range, and good recording data retention characteristics were shown.

Comparative Example 1 The optical recording medium 100 of Example 1
Indicates that the recording layer 20 is Sn-45 atomic% Bi-10 atomic% G
In contrast to having the a film 21a, the optical recording medium 100 of Comparative Example 1 is the optical recording medium 100 in which the recording layer 20 has the Sn-43 atom% Bi film 21b. That is, the difference from Example 1 is that the Sn-43 atom% Bi film 21b was used instead of the Sn-45 atom% Bi-10 atom% Ga film 21a. This will be described below with reference to FIG.

The optical recording medium 100 of Comparative Example 1 has a disk shape as a whole as in Example 1, and a substrate 10, a recording layer 20 and a protective layer (resin layer) 30 are laminated and formed.
The substrate 10 is made of transparent polycarbonate having a thickness of 1.2 mm and is formed in a disc shape. Optical information recording,
The laser light for reproduction enters from the one surface 10a of the substrate 10 as shown by an arrow A as in the first embodiment. One surface 10a of the substrate 10 on the laser light incident side is a smooth surface, and the other surface 10b is provided with a spiral track (guide groove) 10c for guiding the laser light.

An optical recording medium 100 of Comparative Example 1 was manufactured as follows.

Similar to the first embodiment, one surface 10a has a smooth surface,
The thickness of the track 10c formed on the other surface 10b of 1.2
A disc-shaped substrate 10 made of polycarbonate of mm was prepared. On the other surface 10b on which the track 10c is formed, a Sn-43 atom% Bi film 2 is formed by a DC sputtering method.
1b, sputter gas type: Ar, sputter gas pressure: 4 ×
Sn under the film forming conditions of 10 ⁻¹ Pa and input power: 250 W
A 40 nm film was formed using a -43 atom% Bi target.

Next, an ultraviolet curable resin is applied by a spin coating method, and the ultraviolet curable resin is cured by using a high pressure mercury lamp to form a protective layer (resin layer) 30. Was produced.

The recording characteristics of the optical recording medium 100 manufactured in Comparative Example 1 were confirmed.

Recording was performed on the comparative recording medium 100 of Comparative Example 1 under the same recording method and conditions as in Example 1. At this time, the characteristics of the optical recording medium 100 were such that the unrecorded portion reflectance was 45%, the recording laser power was 15 mW, the C / N was 51 dB, and the modulation degree was 90%.

When the recorded optical recording medium 100 was subjected to the same environment resistance test as in Example 1, the unrecorded portion reflectance was 21%. Obvious deterioration of the recording retention characteristics was observed.

[Embodiment 2] (Embodiment 2) This embodiment 2 is an optical recording which has a recording layer and changes the optical characteristics of the recording layer by applying laser light as external energy to record information. In the medium, the recording layer has a first layer and a second layer containing Sn, Bi and Ge which react with each other by applying an external energy, and the second layer is close to the first layer. Then
The optical recording medium is a layer containing WO ₃ .

That is, it is an optical recording medium in which laser light is used as external energy, Ge is used as an oxidizable substance that is more easily oxidized than Sn and Bi, and a first layer and a second layer containing WO ₃ are laminated as a recording layer. FIG. 2 shows a partial cross-sectional structure of the optical recording medium according to the second embodiment. The same reference numerals as those in FIG. 1 are used for the same type of parts.

The optical recording medium 200 of the second embodiment has a disc shape as a whole. As shown in FIG.
The recording layer 20 and the protective layer (resin layer) 30 are laminated. The substrate 10 is made of transparent polycarbonate having a thickness of 1.2 mm and is formed in a disc shape. Laser light for recording and reproducing optical information enters from one surface 10a of the substrate as shown by an arrow A. One surface 10a of the substrate 10 on the laser light incident side is a smooth surface, and the other surface 10b is provided with a spiral track (guide groove) 10c for guiding the laser light.

Sn-42.5 atomic% Bi-1 atomic% Ge
The film 22a is laminated as the first layer of the recording layer 20, the WO ₃ film 23 is laminated as the second layer of the recording layer in the vicinity of the first layer, and graphite is further provided between the first layer and the second layer. (C) The film 24 is laminated. A protective layer (resin layer) 30 made of an ultraviolet curable resin is formed on these layers to cover and protect the recording layer 20.

The optical recording medium 200 of Example 2 was manufactured as follows.

A 1.2 mm-thick polycarbonate disc-shaped substrate 10 having a smooth surface on one side 10a and a track formed on the other side 10b was prepared. Sn was formed on the other surface 10b on which the track was formed by DC sputtering.
-42.5 atomic% Bi-1 atomic% Ge film 22a, sputter gas species: Ar, sputter gas pressure: 4 × 10 ⁻¹ Pa,
A film thickness of 60 nm was formed using an Sn-42.5 atomic% Bi-1 atomic% Ge target under a film forming condition of input power: 500 W.

Subsequently, without breaking the vacuum, the C (graft) film 24 was formed by the RF sputtering method under the conditions of sputtering gas species: Ar, sputtering gas pressure: 4 × 10 ⁻¹ Pa, and input power: 2 kW. , Using C target 1
nm film was formed. Further, by the RF sputtering method, the WO ₃ film 2
3, sputter gas type: O ₂ , sputter gas pressure: 5 × 1
Depending on the film forming conditions of 0 ⁻¹ Pa and input power: 4 kW, WO ₃
A 20 nm film was formed using the target.

Finally, an ultraviolet curable resin is applied by a spin coating method, and the ultraviolet curable resin is cured by using a high pressure mercury lamp to form a protective layer (resin layer) 30. 200 was produced.

The recording characteristics of the optical recording medium 200 manufactured in Example 2 were confirmed.

In the optical recording medium 200 manufactured by the manufacturing method of Example 2, the wavelength was 780 nm from the smooth surface 10a side.
Was recorded on the surface of Sn-42.5 atom% Bi-10 atom% Ge film 22a through an objective lens having an NA (numerical aperture) of 0.5 for recording. Linear velocity is 5.6m
/ Sec, the recording frequency was 800 kHz, and the recording laser waveform was a rectangular wave with a duty ratio of 50%. The characteristics of the optical recording medium at this time are as follows: unrecorded area reflectance is 60%, recording laser power is 15 mW, C / N is 55 dB, and modulation is 72.
%Met.

This recorded optical recording medium 200 was held for 120 hours in an environment of a temperature of 60 ° C. and a relative humidity of 90% as an environment resistance test. After this, C / N, reflectance of unrecorded area,
When the degree of modulation was measured, it was confirmed that no change was observed in any of the characteristics within the measurement error range, and good recording data retention characteristics were shown.

(Comparative Example 2) Optical recording medium 200 of Example 2
The first layer of the recording layer 20 is Sn-42.5 atomic% Bi-
In contrast to having the 1 atomic% Ge film 22a, the optical recording medium 200 of Comparative Example 1 is the optical recording medium 200 in which the first layer of the recording layer 20 has the Sn-43 atomic% Bi film 22b. That is, the difference from Example 1 is that Sn-43.5 atomic% Bi-1 atomic% Ge film 21a is replaced by Sn-43 atomic% Bi film 2.
2b is used. This will be described below with reference to FIG.

The optical recording medium of Comparative Example 2 was prepared as follows.

Similar to the second embodiment, one surface 10a has a smooth surface,
The thickness of the track 10c formed on the other surface 10b of 1.2
A disc-shaped substrate 10 made of polycarbonate of mm was prepared. On the other surface 10b on which the track 10c is formed, a Sn-43 atom% Bi film 2 is formed by a DC sputtering method.
2b, sputter gas type: Ar, sputter gas pressure: 4 ×
Sn under the film forming conditions of 10 ⁻¹ Pa and input power: 250 W
A film having a thickness of 60 nm was formed using a -43 atom% Bi target.

Subsequently, without breaking the vacuum, the C (graft) film 24 was formed by the RF sputtering method under the film forming conditions of sputtering gas species: Ar, sputtering gas pressure: 4 × 10 ⁻¹ Pa, and input power: 2 kW. , Using C target 1
nm film was formed. Further, by the RF sputtering method, the WO ₃ film 2
3, sputter gas type: O ₂ , sputter gas pressure: 5 × 1
Depending on the film forming conditions of 0 ⁻¹ Pa and input power: 4 kW, WO ₃
A 20 nm film was formed using the target.

Finally, an ultraviolet curable resin was applied by a spin coating method, and the ultraviolet curable resin was cured by using a high pressure mercury lamp to form a protective layer (resin layer) 30. 200 was produced.

The recording characteristics of the optical recording medium 200 produced in Comparative Example 2 were confirmed.

Recording was performed on the optical recording medium 200 of Comparative Example 2 under the same recording method and conditions as in Example 2. The recording characteristics of the optical recording medium 200 at this time are as follows: the unrecorded portion reflectance is 63%,
The recording laser power was 14 mW, the C / N was 55 dB, and the modulation was 70%.

When the same environment resistance test as in Example 2 was carried out on the recorded optical recording medium 200, the unrecorded portion reflectance was about 20%. Clear deterioration of recording characteristics was observed.

[0106]

The optical recording medium of the present invention has a recording layer containing Sn and Sn.
Because of the use of fine Bi can exhibit excellent recording characteristics, and
In addition, an oxidizable substance that is more easily oxidized than Sn and Bi , that is, at least one of Ge and Ga is added to the recording layer .
By including it, the durability can be remarkably improved .

The optical recording medium of the present invention has, as a recording layer, a first layer and a second layer which react with each other when external energy is applied, and the second layer is close to the first layer.
In the case where a substance containing at least one or more of S, Se and Te is contained , or W, Mo, Rh, Ag, T
At least one of i, As, Ge, Se and Ce
In the case of containing a substance containing the above element and oxygen as a constituent element, it is excellent in durability and at the same time exhibits an excellent effect in recording characteristics such as reflectance .

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a cross-sectional structure of an optical recording medium of Example 1 and Comparative Example 1.

FIG. 2 is a diagram schematically showing a cross-sectional structure of an optical recording medium of Example 2 and Comparative Example 2.

[Explanation of symbols]

10: Substrate 10a: One surface 10b: Other surface 10c: Track (guide groove) 20: Recording layer 21a: Sn-45 atomic% Bi-10 atomic% Ga film 21b: Sn-43 atomic% Bi film 22a: Sn-42 .5 atomic% Bi-1 atomic% Ge film 22b: Sn-43 atomic% Bi film 23: WO ₃ film 24: graphite (C) film 30: protective layer (resin layer) 100: optical recording medium 200: optical recording medium

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomomi Motohiro, Nagachite-cho, Aichi-gun, Aichi 1-chome, 41, Yokomichi, Yokota Central Research Institute, Ltd. (56) Reference JP-A-2-147288 (JP, A) ) JP-A-63-91836 (JP, A) JP-A-2-243389 (JP, A) JP-A 64-11258 (JP, A) JP-A-58-94147 (JP, A) JP-A 59- 9094 (JP, A) JP-A 2-117887 (JP, A) JP-A 61-156544 (JP, A) JP-A 20001-180114 (JP, A) International Publication 99/020472 (WO, A1) (58) ) Fields surveyed (Int.Cl. ⁷ , DB name) B41M 5/26 G11B 7/24 511

Claims (5)

(57) [Claims] 1. A write-once type light having a recording layer, information is recorded by changing the optical characteristics of the recording layer by applying light or an electromagnetic wave to the recording layer, and the optical characteristics are not changed in non-recording. In the recording medium, the recording layer contains a small amount of Sn, Bi, Ge and Ga.
Both optical recording medium characterized by having at least a first layer; and a substance to be oxidized easily oxidized than the Sn and the Bi made of one. 2. The total of Sn and Bi of the first layer is 1
The composition of Bi when it is set to 00 atom% is 30 to 70 atom%.
In the case of, is 100 atomic% based on the total components of the first layer, wherein a composition <br/> is 0.05 to 30 atomic% of Ga in the case of using Ga as the oxidant, the object The optical recording medium according to claim 1, wherein when Ge is used as the oxidizing substance, the composition of Ge is 0.01 to 2 atomic%. 3. The oxidizable substance is Ge, and Ge or a metal containing a large amount of Ge exists in a grain boundary layer or a grain boundary layer of a Sn—Bi alloy or a metal particle containing Sn or Bi as a main component. Item 1. The optical recording medium according to item 1. 4. The recording layer is adjacent to the first layer,
A substance containing at least one of S, Se, and Te, or
W, Mo, Rh, Ag, Ti, As, Ge, Se and
2. A second layer comprising a substance containing at least one element of Ce and having oxygen as a constituent element and reacting with the first layer by applying light or electromagnetic waves.
4. The optical recording medium according to any one of 3 to 3. 5. The optical recording medium according to claim 1, wherein the recording layer includes only the first layer.