JPH0340238A - Optical recording medium - Google Patents

Abstract

PURPOSE:To reduce time required for rewrite operation and to prevent deterioration in property for repeated use by providing an auxiliary layer for crystallization on the opposite side to the side to be irradiated with light of a recording layer, with the auxiliary layer comprising such a material that has the melting point almost same as the designed temp. of crystallization of the recording material for the recording layer. CONSTITUTION:The auxiliary layer 6 for crystallization comprising such a material that has the melting point almost same as the designed temp. of crystallization of the recording material is provided on the opposite side to the side to be irradiated with light of the recording layer 4. By this constitution, when the recording layer 4 is irradiated with focused light, the auxiliary layer 6 melts to absorb thermal energy and to maintain the recording layer 4 at the designed temp. of crystallization of the recording material. When irradiation is stopped, the auxiliary layer solidifies to emit thermal energy and to maintain the temp. of the recording layer 4 at the designed crystallization temp. of the recording material. Thereby, time for rewrite operation can be reduced and the obtd. optical recording medium has excellent property for repeated use.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention includes a recording layer made of a phase-change recording material, and irradiates the recording layer with focused light from a light source such as a gas laser or a semiconductor laser. The present invention relates to an optical recording medium in which information is optically recorded, reproduced, and erased, and particularly relates to an improvement in an optical recording medium that can shorten the rewriting operation time and has excellent repeatability.

[Prior Art] To explain this type of optical recording medium using a type having a recording layer on one side as an example, as shown in FIG.
A light-transmissive substrate (b) coated with pre-groove (a), a recording 11 (C) formed of a phase change type recording material provided on the entire surface of this plate (b), and Accordingly, a protective layer was provided on the entire surface of the recording layer (C). !
It is known that the main part is composed of one layer (d).

Information is usually written on the optical recording medium (f) by using a high-output circular laser spot from a light source (not shown) as shown in FIGS. 4 to 5 (A). Medium (
The recording layer (C) of f) is irradiated, and the melted part aT0 of the recording material is
While performing the above-mentioned high-temperature rapid heating treatment and rapid cooling treatment to change the irradiated area from crystalline state 1 (Cr) to amorphous state (am), when erasing this written information, As shown in FIG. 5(B), the recording layer (C) is irradiated with a low-power elliptical laser spot at a relatively slow temperature that is above the crystallization temperature T of the recording material and below its melting temperature Tl. A method has been adopted in which the recording region is changed from an amorphous state (am) to a crystalline state (cr) by applying heat treatment and cooling treatment.

[Problems to be Solved by the Invention] By the way, while the recording layer (C) is irradiated with the laser spot, the temperature continues to rise as shown by the solid line in FIG. 6, but the temperature of the optical recording medium (f) continues to rise. When the irradiation area of the laser spot is sequentially shifted due to rotation and is no longer irradiated, the temperature of the recording layer (C) will drop rapidly due to natural cooling.

Therefore, the temperature of the recording layer (C) is maintained at the crystallization temperature Tx of the recording material for a predetermined period of time by irradiation with a low-power oval laser spot, and the recording layer (C) is in an amorphous state (am
) to the crystalline state (CR) to erase recorded information, if the output of this laser spot is too low or the length of the oval laser spot is too small, this recording layer (C ) cannot be maintained at the crystallization temperature T for at least the time required for crystallization, resulting in insufficient crystallization of the recording material and a problem in that the C/N ratio during reproduction decreases.

Therefore, if we try to extend the time to hold this record 1 (c) above the crystallization temperature T by increasing the output of the laser spot to the recording layer (C), the irradiation energy will be extra due to the increased output. As a result, the temperature of the recording material J1 (C) may rise too much, causing segregation of the recording material, resulting in the problem of deterioration of the repeat recording characteristics of the optical recording medium. There is a problem in that internal stress is likely to be applied to the recording layer (C) due to the difference in thermal expansion coefficient between the recording layer (C) and the recording layer (C), resulting in deterioration of recording performance over time.

Another possible method is to lower the rotational speed of the optical recording medium to maintain the recording layer (C) at the temperature of Tx for a predetermined period of time, but since the lowering the rotational speed also slows down the erasing speed, it takes a long time for the rewriting operation. There was a problem that occurred.

[Means for Solving the Problems] The present invention has been made in view of the above-mentioned problems, and its object is to provide an optical recording medium that can shorten the rewriting operation time and has excellent repeatability. The goal is to provide a medium.

That is, the present invention includes a substrate and a recording layer formed on at least one surface of the substrate and made of a phase change recording material, and optically records information by irradiating the recording layer with focused light from a light source. Assuming that the optical recording medium is used for recording, reproducing, and erasing, the surface of the recording layer opposite to the light irradiation surface is made of a material having approximately the same melting temperature as the crystallization setting temperature of the recording material. It is characterized by providing a crystallization auxiliary layer.

In such technical means, the substrate may be made of a transparent single material such as glass, polycarbonate, polyacrylonitrile, polymethyl methacrylate, epoxy resin, or polybentene, or a laminated material of these materials, as in the past. Alternatively, it may optionally be constructed of a metal material such as aluminum. In addition, when a resin material such as polycarbonate is used, in order to prevent thermal damage to the resin material, there is a layer of S, for example, between the substrate and the recording layer.
An inorganic dielectric layer composed of iO%ZrO, ZnS, etc., or a mixture of these two may be interposed.

Next, as the phase change type recording material formed on at least one surface of the substrate, for example, 'reo' is used.

TeOx (Ge1Sn added) and In-8e, I
n-8b1 In-Te, 5b-Te, 5b5e, 3n
-Te, B1-Te, 3i -3e1Te-N1Ge-
Te, binary materials such as Ao-ZnSAs2S3, Ge-
8n-Te, In-3e-Te, In-8b-Te, I
n-3b-3e11n-8e-T11. Ge-8b-T
e1Ge-Te-Tj%Ge-Te-Au, Qe-Te
-CLj, Ge-Te-Go, Ge-Te-N i ,
5b-8e-B i, 5b-8e-Te, 5nSe-
Ternary materials such as Te, and Ge-Te-3b-8e,
Ge-Te-8n-Au, Ge-Te-8b-Au,
Ge-Te-3b-Cu.

Quaternary materials such as Ge-Te-8n-8u, In-8e-TI-Co, etc., or Ga, In, Ta, Ge, S
A material containing at least one element such as n, As, Sb, S, Se, Te, etc. can be used.

In addition, the purpose of preventing the recording layer composed of these phase change recording materials from being deformed after melting until solidification, or
A protective layer may be provided on the recording layer for the purpose of preventing mechanical damage, oxidation, etc. of the recording layer. In this case, the material constituting this protective layer may be none of the above! In addition to the same materials as those constituting the II dielectric layer, ultraviolet curing resin, acrylic,
Resin materials such as polycarbonate and epoxy, glass, etc. can be used. Further, the RJ layer may be formed of a single layer of these materials, or may be formed by laminating a plurality of the above materials. Furthermore, when the portion in contact with the recording layer is made of a resin material, an inorganic dielectric layer may be interposed between the portions like the substrate.

On the other hand, the material constituting the crystallization auxiliary layer has a melting temperature that is approximately the same as the crystallization set temperature of the phase change recording material, and a relatively large heat of solidification (heat of fusion). Any material can be used as long as it can be deposited on a substrate, etc., and materials having a specific melting temperature (melting point) or materials having a certain range of melting temperatures can be used.

Note that phase-change recording materials usually crystallize most efficiently at their crystallization temperature (usually 100 to 400°C), but for recording materials whose crystallization process varies depending on temperature, It does not always crystallize most efficiently.In other words, there are materials whose crystallization time can be shortened by crystallizing at a temperature higher than the crystallization temperature.Therefore, the above-mentioned "crystallization set temperature" refers to does not mean a crystallization temperature, but a specific temperature suitable for crystallizing the recording material.

The crystallization set temperature for an example of a specific recording material will be described below.

■Those whose crystallization temperature is set near the crystallization temperature of the recording material (applied to optical recording media aimed at high reliability).

For example, 1nTeSSb2Se3, Ge Te 1GeTe1 In35Sb45Se2o
1090 Ge2Sb2Te5, GeTeT1, GeTeAu, GeTeCu, QeTeCO1GeTe
Ni1Sb45Se45Bi1o1Ge Te S
b Se , QeTe3b3e, 20 45
25 10 Ge Te Sb Se GeTe5nAu
130 50 5 15) and GeTe5bCu, etc., and to describe the value of the crystallization setting temperature specifically, InTe (crystallization setting temperature: 210°C, crystallization temperature: 200°C, melting point = 6
96℃), G e 1oT e 90 (Crystallization setting temperature: 165℃, Crystallization temperature: 160℃, Melting point: 380
), GeTe (crystallization set temperature: 180°C, crystallization temperature: 100°C, melting point = 125°C), G e 2 S b
2 T e 5 (Crystallization set temperature: 150°C.

Crystallization temperature: 140℃, melting point 2630℃), GeTe
Tj (crystallization setting temperature: 195°C, crystallization temperature: 185
℃), GeTeAu (crystallization setting concentration: 180℃,
Crystallization temperature: 2165°C), GeTeCu (crystallization set temperature: 180°C, crystallization temperature = 161°C), GeTe
GO (crystallization setting temperature: 110°C, crystallization temperature: 163
℃), GeTeN1 (crystallization setting temperature: 165℃, crystallization temperature: 150℃>, Ge2oTe45S b 25
S e , o (crystallization setting m degree: 2oooC, crystallization temperature: 190℃, melting point 2604℃), Ge3oTe5゜5
b5Se15 (crystallization set temperature: 200 °C, crystallization temperature: 180 °C, melting point = 604 °C), GeTe5bSe (crystallization set temperature: 210 °C, crystallization temperature = 200 °C),
GeTe5nALJ (crystallization set temperature: 210°C, crystallization temperature: 200°C), etc.

■Applicable to optical recording media whose purpose is high-speed erasability, where the crystallization temperature is set above the crystallization temperature and below the melting point of the recording material.

For example, In5e1Sb Te, 5b2Se.

23 Sn Te , Bi Te SBi Se3
．． 2080232 Ge Sn Te -In5QSe42Tj3.
8 5 8T There are Sb4oSe45Te15, 5nSeTe, etc., and to specifically describe the value of the crystallization setting temperature, 5b4oSe45Te15 (crystallization setting mi: 160
°C, crystallization temperature = 80 °C, sa: sao °C), 5nSe
Te (crystallization setting temperature: 250°C, crystallization temperature: 90
°C, melting point = 600 °C), etc.

■Those applied to optical recording media whose crystallization temperature is set near the melting point of the recording material and whose purpose is to improve high-speed erasing performance and unerasability.

For example, In5b3Te2 (crystallization set temperature = 455
℃, crystallization temperature: 280℃, melting point: 450℃), etc.

As specific materials for the crystallization auxiliary layer having a melting temperature substantially the same as the crystallization set temperature of the phase change recording material, for example, the following materials can be used.

That is, In (melting temperature 156°C), Li (melting temperature 180°C), S (melting temperature 119°C), W (melting temperature 1
83℃), Yb(i!! Positive temperature 113℃, Bi(
(melting temperature 271°C), Se (melting temperature 217°C), Sn
(g11 dewarming temperature 31℃), Tj (@solutionIll 204
℃〉, materials composed of a single element such as Cd (melting temperature 320℃), Pb (melting temperature 327℃), Bi-C
d (latter content 45%, melting temperature 144°C) In-B
+ (latter content 52.7%, !1 melting temperature 110°C),
Pb-B1 (content of the latter 56.3%, melting temperature 12
5°C), B1-8n (content of the latter 43%, melting temperature 1
39°C), Cd-In (latter 1(7) content 74%, melting temperature 123°C), In-Zn (latter content 4.8%,
melting temperature 143.5°C), K-Tj (latter content 84
．． 3%, melting temperature 113°C), li-Na (latter content 3.8%, melting temperature 171°C), 5n-Pb (latter content 26.1%, melting temperature 183°C), Tj-8
b (content of the latter 29.6%, melting temperature 195'C)
, Tl-8n (content of the latter 69.1%, melting temperature 1
70°C), Zn-8n (the latter content 85%, melting temperature 198°C), etc., and Ao-s; (the latter content 95%,
melting temperature 271°C), As-Pb (latter content 7.4
%, melting temperature 288 °C), As-Tj (latter content 1
9.2%, melting temperature 220°C), Au-Bi (latter content 81.1%, melting temperature 241°C), Au-PbN
1 content 84.4%, melting temperature 215°C), AU-
8n (content of the latter 94%, melting temperature 232°C),
Ba-Pb (content of the latter 93%, melting temperature 113°C
〉, Ll-Bi (latter content 86%, melting temperature 271
°C), Mg-Bi (latter content 95.1%, melting temperature 26a'C), Mn-Bi (latter content 97%)
, melting temperature 270°C>, Na-5r<latter content 78
．． 2%, melting temperature 218°C), 5t-Rh (latter content 1.4%, melting temperature 260°C), zn-sz latter content 91.9%, melting temperature 254.5°C), Cd- P
b (content of the latter 72%, melting temperature 248°C'),
Cd-8b (latter content 7%, melting temperature 290°C)
, Cd-Tj (content of the latter 72.8%, melting temperature 20
3.5°C), Cd-Zn (latter content 26.5%, melting temperature 266°C), Li-Pb (latter content 83%,
melting temperature 235°C), i+-Tl<latter content 844
8%, melting temperature 211°C), fvl-Pb (latter content 84.3%, melting temperature 253°C), MQ-8n
(latter content 91%, melting temperature 200°C), Ma-
TI (latter content 80%, melting temperature 200°C>, p
ci-pb (content of the latter 90.7%, melting temperature 265
), Pt-Pb (latter content 94.1%, melting temperature 290°C), Pb-8b (latter content 17.5%)
, melting temperature 252 °C), Tl-8e (the latter content 70
%~, melting temperature 202°C), Zn5e (content rate of 11 elements ~50%, melting temperature 220°C), Tj-Te (content rate of the latter 69%, melting temperature 200°C), etc., and Aa-
Pb (content of the latter 95.3%, melting temperature 304°C)
, Ao-Te (content of the latter 67%, melting temperature 35
1°C), Ao-Tj (latter content 97%, melting temperature 302°C), Al-Zn (latter content 88.7%)
, melting temperature 382°C>, AU-Ge (content of the latter 27
%, melting temperature 356 °C), AU-8b (the latter content 3
5%, melting temperature 360 °C), ALJ-Si (latter content 31%, melting temperature 370 °C), Go-Te (latter content 70%, melting temperature 340 °C), Ge-Te (latter content rate 85%, melting temperature 375'C), Zn-G
e (latter content 5.5%, melting temperature 400°C>, K
-8b (latter content 68%, melting temperature 400°C), M
a-1n (when the latter content is 28%, the melting temperature is 343 °C, and when the latter content is 92.3%, the melting temperature is 367 °C), Na-8b (the latter content is 60 °C),
．． 6%, melting temperature 340°C), Na-e (latter content 57%, melting temperature 319°C), Zn-Pb (latter content 98.4%, melting temperature 327°C), etc. is available.

Note that other elements may be added to these materials and used as constituent materials of the crystallization auxiliary layer.

Here, the crystallization auxiliary layer acts not only when changing the recording material of the recording layer from an amorphous state to a crystalline state, but also when changing from a crystalline state to an amorphous state. It acts on

However, compared to the temperature conditions for changing from an amorphous state to a crystalline state (usually set above the crystallization temperature of the recording material), the temperature conditions for changing from a crystalline state to an amorphous state are (Set above the melting temperature of the recording material)
is high, and even if thermal energy is released from the crystallization auxiliary layer due to solidification during the rapid cooling process, this thermal energy will be instantly diffused to the surroundings. Moreover, since this crystallization auxiliary layer becomes amorphous or crystallizes in an incomplete state during the rapid cooling process, it solidifies in a high energy state, so that less thermal energy is released. Therefore, the crystallization auxiliary layer does not adversely affect the amorphization of the recording material.

In addition, the recording layer and the crystallization auxiliary layer are used when information is corrupted.
Alternatively, during erasing, they may become molten with each other, resulting in mutual diffusion. Therefore, in order to prevent this mutual diffusion, a diffusion prevention layer may be interposed between the recording layer and the crystallization auxiliary layer.

The material constituting this diffusion prevention layer must have a higher melting temperature than the materials constituting the recording layer and the crystallization auxiliary layer, such as Ao (melting point 960°C).
), AL+ (melting point 1063°C) Be (melting point 1287°C)
, Cu (melting point 1083°C), Nb (!! point 2520°C)
, Ru (Fa point 2250°C), Ta CM point 2990
℃), Cr (melting point 1890℃), Ti (melting point 1680℃)
℃> and high melting point metals such as Zr (melting point 1855℃), Zn5 (melting point 1700℃), Pb5 (melting point 1114℃
), 5i02 (Fy1 point 1700℃), Al203 (!
1 point 2050℃>, GeO2 (W1 point 1080℃), T
aC (ie point 3120℃), ZnTe (1 point 1239℃
), AIN (melting point 2200℃), TiN (melting point 200℃), AIN (melting point 2200℃), TiN (melting point 200℃
0°C or higher) TaN (81 points 2000°C or higher), and
■Compounds such as n2S03 (melting point 900°C) or alloys can be used. Incidentally, as a method for forming this diffusion prevention layer, the recording layer, the crystallization auxiliary layer, etc., a sputtering method, a vacuum evaporation method, etc. can be used.

In addition, in the optical recording medium in this technical means,
The amorphous phase (non-crystalline phase) of the recording material constituting the recording layer may be made to correspond to the recorded state and its crystalline phase may be made to correspond to the erased state.On the contrary, the amorphous phase may be made to correspond to the erased state and its crystalline phase may be made to correspond to the erased state. The phase may be made to correspond to the recording state, and the selection thereof is arbitrary.

[Function] According to the above-mentioned technical means, a crystal made of a material having substantially the same melting temperature as the crystallization set temperature of the recording material is formed on the side of the recording layer opposite to the light irradiation surface. Since the crystallization auxiliary layer is provided, the recording layer can be maintained at the crystallization set temperature of the recording material by absorbing thermal energy accompanying melting of the crystallization auxiliary layer while the recording layer is irradiated with focused light. On the other hand, after the focused light irradiation is released, it becomes possible to maintain the recording layer at the crystallization set temperature of the recording material by releasing thermal energy accompanying solidification of the crystallization auxiliary layer.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the optical recording medium according to this example includes a polycarbonate substrate (2) on which pre-groups (1) are formed, and a film deposited on this substrate (2) by sputtering. An inorganic dielectric layer <3> made of SiO2 with a thickness of 1000 to 2000 angstroms to prevent thermal damage to the substrate (2), and a film with a thickness of 500 to 2000 angstroms deposited on this inorganic dielectric layer (3) by vapor deposition. 1000 angstrom recording layer (4) made of In-8e alloy (composition ratio 1:1)
On this recording layer (4), a diffusion prevention layer <5) made of InSe3 (molten metal temperature 900°C) having a thickness of 10 to 100 angstroms was deposited by vapor deposition, and on this diffusion prevention layer <5). A viscous crystallization auxiliary layer 6 made of Bi having a thickness of 1000 angstroms was deposited by vapor deposition on the crystallization auxiliary layer (6), and the recording layer (4) was deposited by vapor deposition on this crystallization auxiliary layer (6).
) Thickness 1000~2 to prevent thermal deformation and mechanical damage
The main part is composed of a protective layer (7) made of 8102 with a thickness of 0.000 angstroms.

Further, in this optical recording medium, the amorphous phase of the recording material corresponds to the recorded state, while the crystalline phase of the recording material corresponds to the erased state, as in the prior art.

That is, a 20W high-power laser beam is applied to the recording layer (4).
The recording material (In-8
After heating the recording material to the melting temperature T12 (650° C.) of the e-based alloy) and rapidly cooling it, the recording material is changed from a crystalline state to an amorphous state, and writing is performed.
The recording material is changed from an amorphous state to a crystalline state by irradiating the OW low-power laser beam to the area to be erased in the recording layer <4> and heating it for a certain period of time to a temperature higher than the crystallization temperature Tx (270°C) of the recording material. It is now possible to erase the data by pressing the button.

The temperature increase characteristics of Bi constituting the crystallization auxiliary layer (6) of this optical recording medium and the 1n-3 constituting the recording layer (4)
The temperature rise characteristics of e-based alloys are shown in Figures 2(A) to 2(A), respectively.
It is as shown in B). That is, B1 constituting the crystallization auxiliary layer (6) is In, which constitutes the recording layer (4>).
It has a melting temperature T1 (271°C) that is almost the same as the crystallization temperature Tx (270°C) of the -8e series alloy, and its solidification heat also shows a large value of 2.1 cal/mol. , the plateau region from t1 to t2, which is the region of phase transition from solid phase to liquid phase, is long as shown in FIG. 2(A).

Therefore, when irradiating a part of the recording layer (4) with a low-power laser beam of 10 W to erase the information, the recording layer (4) is supplied with thermal energy from the laser beam. ) is the crystallization temperature Tx (27
When the temperature reaches 0°C, the crystallization auxiliary layer (
Since the crystallization auxiliary layer (6) absorbs thermal energy from the laser beam until the melting of the crystallization auxiliary layer (6) is completed, the temperature of the recording layer (4) is lower than that of the crystallization auxiliary layer (6). The melting temperature T1 (271° C.) of Bi constituting the recording layer (4) is maintained at the crystallization temperature Tx (270° C.) of the In-8e alloy constituting the recording layer (4).

Therefore, the temperature of the recording layer (4) does not rise too much during laser beam irradiation when erasing information.
It has the advantage that segregation of the In-8e alloy, which is the recording material, is difficult to occur and the repeatability is maintained over a long period of time.

In addition, after the laser beam irradiation is stopped, since the solidification heat of B1 is 2.7 Kcal/mol, as the crystallization auxiliary layer (6) composed of 3i is solidified, its 1 Bit (diameter 1μ7+'L, film thickness 100
0 angstroms = 0.1 μmrL) to 1O-12
cal thermal energy will be released. and,
Since the energy required for the In-8e alloy constituting the recording layer (4) to transition from an amorphous state to a crystalline state is approximately o-13 cal per bit, the crystallization auxiliary layer (6) Even if the thermal energy emitted from the recording layer (4) diffuses to areas other than the recording layer (4), it is possible to supply sufficient thermal energy to the recording layer (4) to promote crystallization.

Therefore, even after the laser beam irradiation is stopped, the temperature of the recording layer (4) is maintained at the crystallization temperature Tx (270°C) of the 1n-8e alloy, so the laser beam during erasing is The irradiation time has been increased from 5μs to 1μs.
It has the advantage that it can be shortened to less than μS.

Furthermore, Fig. 3 shows this, and even if the irradiation power of the laser beam (not shown by the broken line in the figure) is set the same as before, the temperature of the recording layer (4>) remains unchanged for a long time. It can be understood from the thermal history of the recording layer (4) shown by the solid line that it is maintained at the crystallization temperature Tx of the material.Also, the two-dot chain line shows the recording layer of a conventional optical recording medium without a crystallization auxiliary layer. This shows the thermal history of

On the other hand, when writing information by irradiating a part of the recording layer (4) with a high-power laser beam of 20 W, the temperature conditions for raising the temperature of this recording layer (4) are based on the recording material In- The melting temperature T of the 8e alloy is higher than 2 (650°C), which is higher than its crystallization temperature Tx (270°C). Even if energy is released, this thermal energy will be instantly diffused to the surroundings, and furthermore, this crystallization aid II (6) may become amorphous or remain incompletely crystallized during the rapid cooling process. Since the crystallization is solidified in a high energy state such as oxidation, the amount of heat energy released is also reduced. Therefore, the crystallization auxiliary layer (6) does not interfere with the rapid cooling process.

[Effects of the Invention] According to the present invention, a crystallization auxiliary layer made of a material having substantially the same melting temperature as the crystallization set temperature of the recording material is provided on the side of the recording layer opposite to the light irradiation surface. Because we have established
While the recording layer is irradiated with focused light, the recording layer can be maintained at the crystallization set temperature of the recording material by absorption of thermal energy accompanying melting of the crystallization auxiliary layer,
On the other hand, after the focused light irradiation is released, the recording layer can be maintained at the crystallization set temperature of the recording material by releasing thermal energy accompanying solidification of the crystallization auxiliary layer.

Therefore, even when the rotational speed of the optical recording medium is increased or the output of the focused light is increased, the recording layer is maintained at a temperature suitable for crystallizing the recording material, so that no rewriting can be performed. The operation time can be shortened, and
This has the effect that the repeatability does not deteriorate.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an optical recording medium according to an embodiment of the present invention, FIG. (B) is a graph showing the temperature rise characteristics of the recording material constituting the recording layer of the optical recording medium, and FIG. 3 is a graph showing the thermal history during erasing of the recording layer in this optical recording medium. Fig. 4 is a partial cross-sectional perspective view showing the structure of a conventional optical recording medium, Figs. 5 (A) to (8) are diagrams explaining the principle of recording and erasing information in an optical recording medium, and Fig. 6 is a conventional optical recording medium. FIG. 2 is a graph diagram showing a thermal history during erasing of a recording layer in a medium. [Explanation of symbols] (2)...Substrate (4)...Recording layer (5>...Diffusion prevention layer (6)...Crystallization auxiliary layer patent Applicant: Fuji Xerox Co., Ltd. Agent) Patent attorney Tomohiro Nakamura (2 others) (A) Time (B) Time period 3 Figure 4 Figure 4 Irradiation power 1-0--t

Claims (2)

[Claims] (1) Comprising a substrate and a recording layer formed on at least one surface of the substrate and made of a phase-change recording material, the recording layer is irradiated with focused light from a light source to optically record information. In an optical recording medium for reproducing and erasing, a crystallization auxiliary layer made of a material having a melting temperature substantially the same as the crystallization set temperature of the recording material is provided on the side opposite to the light irradiation surface of the recording layer. An optical recording medium characterized by being provided with. (2) A diffusion prevention layer is interposed between the recording layer and the crystallization auxiliary layer to prevent the materials constituting each layer from diffusing to the other side. optical recording media.