JP2006277839A - Optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform high speed recording to a semitransmission information layer without making laser power excessive and without spoiling thermal stability of an amorphous mark in an optical recording medium having two or more information layers. <P>SOLUTION: The optical recording medium 10 has a substrate 12, a first information layer 14 provided on a light incident side of the substrate 12 and a second information layer 16 to be the semitransmission information layer provided on the light incident side further than the first information layer and the second information layer 16 includes a recording film 18 and an interface layer 20 provided adjacently to the recording film on the light incident side of the recording film 18 and composed of Cr<SB>2</SB>O<SB>3</SB>. The recording film 18 has 30 to 80% light transmittance to a laser beam and is formed by using a phase change material which consists essentially of Sb and Ge and is rewritable by an optical system of λ/NA≤650 nm when a numerical aperture of an objective lens and the wavelength of the laser beam are defined as NA and λ, respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical recording medium called a next generation DVD (digital versatile disk).

  A next-generation DVD has been proposed that uses an optical system having a laser wavelength of 405 nm (blue) and a numerical aperture NA = 0.85 of an objective lens. It has two information layers on one side, and has a rewriting speed. A rewritable optical recording medium having a single speed (linear velocity of about 5.0 m / s) has been commercialized.

  In such a next-generation DVD, further increase in storage capacity and higher speed recording are required.

  In the optical recording medium having two layers or more information layers on one side as described above, the information layers other than the information layer farthest from the light incident surface of the laser beam are not connected to the information farthest from the light incident surface. Semi-transmission is used to enable recording and reproduction.

  In this case, it is necessary to reduce the thickness of the phase change recording film included in the information layer. However, as the film thickness is reduced, the crystallization speed and the erasure rate decrease, and the recording mark (amorphous) is erased. (Crystallization) becomes difficult and the rewriting speed is reduced.

  The reduction in the erasure rate becomes more remarkable as the time for the laser beam spot size to pass through a certain point on the phase change recording film becomes shorter. That is, the higher the linear velocity, the lower the erasure rate. Therefore, the higher the density and capacity of the optical recording medium, the more difficult it is to improve the rewriting speed.

As a means for improving the crystallization speed of the phase change recording film as described above, for example, as described in Patent Document 1, a phase change recording film made of a compound phase change material such as Ge ₄ Sb ₂ Te _{7 is} used. It is disclosed that Cr ₂ O ₃ is used as the interface layer, and the effect of improving the number of rewrites by preventing the diffusion of ZnS into the recording film and improving the crystallization speed can be obtained.

  However, compound-based phase change materials such as GeSbTe and GeBiTe have a very high melting point of 600 ° C. or higher. On the other hand, in the semi-transmissive information layer in the multilayer optical recording medium, the film thickness is thin, so the heat of the laser beam Therefore, the laser power required to melt the phase change recording film in the semi-transmissive information layer is increased. Furthermore, as the rewriting speed in the optical recording medium increases, the time for the laser beam to pass through the phase change recording film is shortened as described above, so that the laser power is increased to melt with the recording film. There must be.

  However, the semiconductor laser that outputs a laser beam having a wavelength of 405 nm has just been put into practical use, and a high-power type semiconductor laser has not yet been put into practical use. High-speed recording could not be performed using a compound material such as GeSbTe or GeBiTe having a high melting point as described above.

  In contrast, when an SbTe eutectic material containing Sb as a main component is used as the phase change recording film, the crystallization rate can be controlled by the Sb content, and the melting point is higher than that of the compound material. Since the temperature is 600 ° C. or lower, the power of the laser beam for forming the amorphous mark can be reduced.

  However, when this SbTe eutectic material is used as a recording film, if the Sb content is increased in order to cope with high-speed recording, the crystallization / activation energy decreases and the thermal stability of the amorphous mark This causes the problem of damage.

JP 2003-228881 A

  The present invention has been made in view of the above problems, and can perform high-speed recording without increasing the laser power for forming an amorphous mark and without impairing the thermal stability of the amorphous mark. It is an object to provide a medium.

As a result of diligent research, the present inventor has formed a recording film of a phase change material in the semi-transmissive information layer with Sb and Ge as main components and Mg as an additive component, and laser beam light is applied to the recording film. It has been found that by forming the interface layer adjacent to the incident side from Cr ₂ O ₃ , high-speed recording can be performed without excessive laser power and without impairing the thermal stability of the amorphous mark. It was.

  That is, the following problems are solved by the present invention.

(1) A substrate, a first information layer provided on the light incident side of the laser beam in the substrate, and at least one semi-transmissive information layer provided further on the light incident side than the first information layer The semi-transmissive information layer includes a recording film and an interface layer provided adjacent to the light incident side of the recording film, and has a light transmittance with respect to the laser beam. It is a phase change material that can be rewritten by an optical system of λ / NA ≦ 650 nm with 30 to 80%, Sb and Ge as main components, NA of the objective lens and NA of the wavelength of the laser beam. An optical recording medium formed, wherein the interface layer is made of Cr ₂ O ₃ .

  (2) The optical recording medium according to (1), wherein the recording film has Sb of 70 at% to 94 at% and Ge of 5 at% to 21 at%.

  (3) The optical recording medium according to (1) or (2), wherein the recording film contains 1 at% or more and 10 at% or less with Mg as an additive component.

  (4) The optical recording medium according to (1), (2), or (3), wherein the thickness of the interface layer is 0.2 nm or more and 8 nm or less.

  (5) The optical recording medium according to (1), (2) or (3), wherein the thickness of the interface layer is 0.2 nm or more and 5 nm or less.

In the optical recording medium of the present invention, the recording film is made of an SbGe eutectic material, and an interface layer made of Cr ₂ O ₃ is formed on the laser beam incident side, but it is estimated that Cr ₂ O The interfacial layer ₃ promotes the generation of crystal nuclei from the interface of the recording film, the crystal nuclei are rapidly grown from the generated crystal nuclei, the crystallization time is shortened, without increasing the laser power, and High-speed recording is possible without impairing the thermal stability of the amorphous mark.

An optical recording medium according to the best mode includes a substrate, a first information layer provided on the light incident side of the laser beam on the substrate, and a half provided on the light incident side further than the first information layer. A translucent information layer, and the semi-transparent information layer includes a recording film and an interface layer provided adjacent to the light incident side of the recording film, and is configured to emit light for the laser beam. Rewriting is possible with an optical system of λ / NA ≦ 650 nm when the transmittance is 30 to 80%, Sb and Ge are the main components, the numerical aperture of the objective lens is NA, and the wavelength of the laser beam is λ. The interface layer is made of Cr ₂ O ₃ .

  As a configuration example of the transflective information layer, a first dielectric layer, a reflective layer, a second dielectric layer, a recording film (layer), an interface layer, a third dielectric layer, and a heat dissipation layer are sequentially stacked on a substrate. The thing which was done is mentioned.

The first dielectric layer is provided for protecting the reflective layer and adjusting the light transmittance, and the material is not particularly limited. Ti, Zr, Hf, Ta, Si, Al, Mg, Y, Ce, Zn An oxide, nitride, sulfide, carbide, fluoride, or a composite thereof containing at least one metal selected from In, Cr, Nb, or the like is used. In the best mode, it is formed of a material containing zirconium oxide as a main component. The main component here means that the molar ratio to the whole is 60% or more. The film thickness D ₁ of the first dielectric layer is preferably ₁ nm ≦ D ₁ ≦ 60 nm. If the thickness is less than 1 nm, the protection of the reflective layer is insufficient, and if it is thicker than 60 nm, the light transmittance is out of the preferred range.

  The reflective layer is provided for heat dissipation and optical interference effect, and an Ag alloy is preferably used as the material, and the film thickness Tr is 0 <Tr <30 nm for a semi-transmissive structure. More preferably, 0 <Tr <20 nm. The preferred film thickness Trec of the recording film (layer) is 2 nm ≦ Trec ≦ 12 nm, preferably 2.5 nm ≦ Trec ≦ 8 nm.

  Accordingly, the light transmittance at the recording wavelength of the entire transflective information layer is set to be 30% or more and 80% or less. If the light transmittance of the semi-transmissive information layer is less than 30%, it becomes difficult to record on the information layer farthest from the light incident surface of the laser beam, and if it exceeds 80%, it becomes difficult to record on the semi-transmissive information layer. Because.

  The recording film (layer) is composed of at least Sb and Ge. Further, at least one additive component selected from Mg, Al, Si, Mn, Zn, Ga, Sn, Bi, In, and the like may be included.

  A preferable atomic weight ratio of Sb is 70 ≦ Sb ≦ 94, and more preferably 77 ≦ Sb ≦ 90. If Sb is less than 70 at%, the crystallization speed decreases, and it becomes difficult to erase the mark. In addition, the thermal stability of the mark is impaired. A preferred atomic weight ratio of Ge is 5 ≦ Ge <22, and more preferably 8 ≦ Ge ≦ 21. If Ge is less than 5 at%, the thermal stability of the mark is impaired. On the other hand, if it is 22 at% or more, the crystallization speed is lowered and erasure becomes difficult. A preferable atomic weight ratio of at least one additive component selected from Mg or the like is 1 ≦ Mg ≦ 10. If Mg is less than 1 at%, a noise reduction effect cannot be obtained. On the other hand, if it exceeds 10 at%, the crystallization speed is lowered and erasure becomes difficult.

The second dielectric layer controls the protection of the recording layer and the reflective layer and controls the heat dissipation from the recording layer to the reflective layer. The material is not particularly limited, and is an oxide or nitride containing at least one metal selected from Ti, Zr, Hf, Ta, Si, Al, Mg, Y, Ce, Zn, In, Cr, Nb, and the like. Sulphides, sulfides, carbides, fluorides, or composites thereof. In the embodiment of the present invention, it is formed of a material containing zirconium oxide as a main component. The main component means that the molar ratio to the whole is 60% or more. The film thickness D ₂ is preferably ₂ nm ≦ D ₂ ≦ 20 nm. If the thickness is less than 2 nm, the protection of the recording layer and the reflective layer is insufficient. If the thickness is greater than 20 nm, the heat from the recording layer cannot quickly escape to the reflective layer, and the cooling rate decreases to accurately form an amorphous mark. Difficult to do.

The interface layer controls the crystallization rate. By using Cr ₂ O ₃ as the interface layer, the crystallization speed can be improved. The film thickness Ti of the interface layer is 0.2 nm ≦ Ti ≦ 8 nm. If the film thickness of the interface layer is less than 0.2 nm, the rewritable maximum linear velocity cannot be obtained, and if it is thicker than 8 nm, the rewritable maximum linear velocity is improved. However, the transflective information is obtained by light absorption by the Cr ₂ O ₃ film. It reduces the light transmittance of the layer.

The third dielectric layer adjusts optical characteristics and controls heat dissipation from the recording layer to the heat dissipation layer. The material is not particularly limited, and is an oxide or nitride containing at least one metal selected from Ti, Zr, Hf, Ta, Si, Al, Mg, Y, Ce, Zn, In, Cr, Nb, and the like. Sulphides, sulfides, carbides, fluorides, or composites thereof. Preferably, it is formed by a mixture of ZnS and SiO ₂ . A preferred molar ratio of ZnS to SiO ₂ is 50:50 to 95: 5. Outside this range, the refractive index of the mixture of ZnS and SiO ₂ changes, making it difficult to adjust the optical characteristics. The thickness D ₃ of the third dielectric layer is preferably 5 nm ≦ D ₃ ≦ 50 nm. If the thickness is less than 5 nm, it is difficult to protect the recording layer and adjust the optical characteristics. If the thickness is more than 50 nm, the heat dissipation from the recording layer to the heat dissipation layer decreases.

The heat dissipation layer is for controlling the heat dissipation from the recording layer and enhancing the cooling effect of the recording layer to facilitate the accurate formation of the amorphous mark. The material is not particularly limited, but a material having higher thermal conductivity than the material of the third dielectric layer is preferable, and AlN, SiN, BN, Al ₂ O ₃ , TiO _{2 and the} like are preferable. In the best embodiment, it is formed by AlN. A preferred film thickness Theat of the heat dissipation layer is 15 ≦ Theat <150 nm, and more preferably 20 ≦ Taln <120 nm. When the film thickness of the heat dissipation layer is less than 15 nm, the heat dissipation effect from the recording layer is reduced, and when it is 150 nm or more, the time required for film formation becomes long and the productivity is lowered.

  The first, second and third dielectric layers may be composed of a single layer or a plurality of dielectric layers of two or more layers.

  Hereinafter, an optical recording medium 10 according to the first embodiment of the present invention will be described in detail with reference to FIG.

  The optical recording medium 10 includes a substrate 12, a first information layer 14 provided on the light incident side (upper side in FIG. 1) of the substrate 12, and light further than the first information layer 14. A second information layer 16 which is a transflective information layer provided on the incident side, and the second information layer 16 is adjacent to the recording film 18 and the light incident side of the recording film 18. The interface layer 20 is provided.

  A spacer layer 22 is provided between the first information layer 14 and the second information layer 16, and a light transmission layer 24 is provided on the light incident side of the second information layer 16. .

The second information layer 16 is composed of, for example, a first dielectric layer 26 made of a ZrO ₂ film having a thickness of 5 nm and an AgPdCu (98: 1: 1 at%) film having a thickness of 10 nm, for example, from the spacer layer 22 side. A reflective layer 28, a second dielectric layer 30 made of, for example, a 4 nm-thickness ZrO ₂ film, the recording film 18 having a thickness of 6 nm, and an interface layer 20 made of, for example, a 5 nm-thickness Cr ₂ O ₃ film For example, a third dielectric layer 32 made of a ZnS: SiO ₂ (80:20 mol%) film having a thickness of 10 nm and a heat dissipation layer 34 made of an AlN film having a thickness of 50 nm, for example, are formed in this order by sputtering. Has been.

  The substrate 12 is made of polycarbonate having a thickness of 1.1 mm, the spacer layer 22 has a thickness of 25 μm, and the light transmission layer 24 has a thickness of 75 μm by spin coating using an ultraviolet curable resin. Is formed. The light transmission layer 24 is formed after the second information layer is crystallized by an initializer.

  In Example 1, the recording film 18 is made of SbGeMg (84.0: 14.0: 2.0 at%).

  Recording is performed on the optical recording medium 10 according to the first embodiment with a laser beam having a wavelength of 405 nm using an optical system with NA = 0.85 under the condition of a recording signal (1, 7) RLL modulation signal. Evaluated. Here, the linear velocity of recording / erasing was performed at an optimum linear velocity for each sample, and reproduction was performed at a linear velocity of 5.3 m / s.

For the optical recording medium 10 of Example 1, a comparative optical recording medium in which no interface layer is provided between the recording film and the third dielectric layer (ZnS: SiO ₂ film) is prepared. The samples were recorded under the same conditions as described above and evaluated. Regarding the optical recording medium 10 of Example 1 and the optical recording medium of the comparative example, the erasing characteristics were compared as follows, and the change in the crystallization speed due to the interface layer was examined.

  First, after recording an 8T signal at a linear velocity of 10.5 m / s, DC erasure was performed once at each linear velocity while changing the linear velocity, and the change in carrier level was measured to determine the erasure rate at each linear velocity. It was measured. At this time, the power of 8T signal recording is Pw (recording power) / Pe (erasing power) / Pb (bias power) = 9.6 / 3.2 / 0.3 mW, and the erasing power of DC erasing is 3.5 mW. did.

  In FIG. 2, the measured relationship between the linear velocity and the erasure rate is indicated by a solid line in the case of the optical recording medium of Example 1 and by a one-dot chain line in the case of the comparative example.

From FIG. 2, it can be seen that by forming the interface layer from Cr ₂ O ₃ , a high erasure rate can be obtained even at a high linear velocity, and the crystallization rate can be increased without changing the composition of the recording film material. .

Further, when the optical transmittance of the optical recording medium 10 of Example 1 and the information layer of the comparative example were measured by a spectrophotometer, the third dielectric layer (ZnS: SiO2) of Example 1 was found to be 41%. in ₂ film) was 43.5%.

In the optical recording medium 10 of Example 1, when the substrate side interface layer made of Cr ₂ O ₃ was provided on the substrate 12 side of the recording film 18, the erasure rate was not changed. This is presumably because the temperature reached at the time of recording / erasing in the interface layer 20 on the light incident side is higher than that on the substrate side.

As another comparative example, an InSbTeGe (1.0: 76.0: 18.0: 5.0 at%) recording film and an InSbTeGeMn (0.9: 72.6: 17.2: 4.8: 4) are used. .5at%) using a recording film, and each creates an optical recording medium in which to form an interface layer of Cr ₂ O _3, a result of the check the effect of improving the crystallization rate due to Cr ₂ O ₃ interface layer is obtained Are shown in FIGS. 3 and 4, respectively.

FIGS. 3 and 4 show that the SbTe eutectic recording film material does not show the effect of improving the crystallization speed due to the Cr ₂ O ₃ interface layer, and the InSbTeGeMn recording film has a lower crystallization speed. .

From the above, even in the case of a eutectic recording film material containing Sb as a main component, the crystallization speed is improved by the Cr ₂ O ₃ interface layer in the SbGe eutectic material, whereas the SbTe eutectic is It can be seen that there is no change in the crystallization rate in the system material, or it is decreased. It can also be seen that the effect of improving the crystallization speed by the Cr ₂ O ₃ interface layer greatly depends on the material of the phase change recording film in contact with the interface layer.

  One reason for the effect of improving the crystallization rate is not clear, but can be estimated as follows.

It is considered that the Cr ₂ O ₃ interface layer promotes the generation of crystal nuclei from the interface of the phase change recording film, and crystal growth is rapidly performed from the crystal nuclei generated thereby, thereby shortening the crystallization time. In the above SbGe eutectic material, it is considered that not only crystal growth but also crystal nucleation occurs, and therefore the efficiency of crystal nucleation of the phase change recording film is greatly promoted by the Cr ₂ O ₃ interface layer. It is considered that the crystallization speed is improved.

On the other hand, in the SbTe eutectic material, crystal nucleation is hardly observed in crystallization, and it is known that crystal growth is dominant. Even if a Cr ₂ O ₃ interface layer is provided, the SbTe eutectic material is provided. In the case of the system phase change recording film material, it is considered that crystal nucleation cannot be promoted and thus the crystallization speed is not improved.

  FIG. 5 shows the result of jitter value measurement when the recording power was changed under the condition of the linear velocity of 21.0 m / s in the optical recording medium according to Example 1.

  Here, the ratio of erasing power to recording power (Pe / Pw) was kept constant at 0.3, recording was performed while changing the recording power and erasing power, and the jitter value was measured. The bias power Pb was 0.5 mW. From FIG. 5, it was possible to obtain good jitter characteristics with a practical jitter value of 10% or less at a high linear velocity of 21.0 m / s. Furthermore, it can be seen that the optimum recording power was about 10 to 11 mW, and high-speed recording was possible with a sufficiently low power.

Next, an optical recording medium (samples 1 to 7) having the same configuration as in Example 1 was used, and SbGeMg (85.0: 13.0: 2.0 at%) was used as the recording film material. The results of measuring the change in erasure rate in relation to the linear velocity when the film thickness of the Cr ₂ O ₃ interface layer is 0.0 nm, 0.2 nm, 0.5 nm, 0.9 nm, 3 nm, 5 nm, and 8 nm. Table 1 shows.

As conditions, 8T mark signals were recorded on the optical recording media of Samples 1 to 7, DC erasing was performed while changing the erasing linear velocity at an erasing power of 4 mW, and the erasing rate was measured. When the Cr ₂ O ₃ film thickness was 0 nm and 0.2 nm, the recording linear velocity was 9.8 m / s, and when the film thickness was 0.5 to 8 nm, the recording linear velocity was 19.6 m / s. After performing the erasure rate measurement, the maximum linear velocity at which the erasure rate was 25 dB was obtained, and this was set as the rewritable linear velocity.

As a result, the preferable film thickness of Cr ₂ O ₃ is 0.2 nm or more and 8 nm or less. If the thickness is thinner than 0.2 nm, the effect of improving the rewritable maximum linear velocity cannot be obtained, and if it is thicker than 8 nm, the rewritable maximum linear velocity is greatly improved. However, information is absorbed by light absorption by the Cr ₂ O ₃ film. This is because the light transmittance of the layer is reduced. Furthermore, since Cr ₂ O ₃ has a slower sputter rate, the thinner the one, the higher the productivity. From the viewpoint of this productivity and the maximum linear velocity, the maximum linear velocity is less than 5 nm. In order to reduce the total layer thickness including the information layer, the thickness of the Cr ₂ O ₃ film is preferably 0.9 nm or less.

The results shown in Table 1 above are shown in FIG. 6 for the relationship between the erase linear velocity and the erase rate for each Cr ₂ O ₃ film thickness. FIG. 7 shows the relationship between the Cr ₂ O ₃ film thickness and the maximum rewritable linear velocity.

  In Example 3, an optical recording medium (samples 8 to 15) similar to that in Example 1 in which the composition of the SbGeMg recording film was changed was prepared. Similarly to the above, after recording the 8T mark, the DC velocity was changed while changing the linear velocity. The erasure rate when erasing once with an erasing power of 4 mW was measured. Further, from the relationship between the erasing linear velocity and the erasing rate, the linear velocity at which an erasing rate of 25 dB, which is an erasable standard, was obtained. This erasable maximum linear velocity is the maximum rewritable linear velocity, and the higher the numerical value, the higher the recording speed.

  The measurement results are shown in Table 2. As can be seen from Table 2, sample 8 was erasable even at a linear velocity of 40 m / s, but the signal reproduction mark after recording mark formation partially crystallized, causing reproduction deterioration. This is considered to be a result of a decrease in the thermal stability of amorphous because the crystallization rate is too high.

  In sample 15, the mark could not be erased. This is considered to be a result of a marked decrease in the crystallization rate. From the above results, the preferable composition ranges of Sb and Ge are 77 at% to 90 at% and Ge is 8 at% to 21 at%.

  Further, according to the experiment by the present inventor, when Mg is less than 1 at%, the noise reduction effect cannot be obtained, and when it exceeds 10 at%, the crystallization speed decreases, so the Mg composition becomes 1 at% or more and 10 at% or less. .

[Comparative example]
In the comparative example, an optical recording medium was prepared in the same manner as in Example 1 with a recording film composition of GeSbTe and GeBiTe, and after recording an 8T mark on this optical recording medium, the linear velocity was changed. Erasing was performed once with an erasing power of 4 mW, and the maximum linear velocity at which erasing was possible with or without the Cr ₂ O ₃ interface layer was determined.

  The results are shown in Table 3. The numerical value of the recording film composition indicates the ratio of each element.

From the above, high-density recording with a short wavelength and high NA does not provide high-speed crystallization in both the compound recording film composition and the combination of this and the Cr ₂ O ₃ interface layer. It turned out to be difficult to achieve. This is presumed to be because the amorphous crystallization process depends only on nucleation, and crystal growth after nucleation does not occur, so the nucleation promotion effect by the interface layer cannot contribute to the improvement of crystallization speed. Is done.

  The above embodiment is for an optical recording medium having two information layers. However, the present invention is not limited to this, and can be applied to an optical recording medium having three or more information layers. Is.

Sectional drawing which shows typically the optical recording medium based on Example 1 of this invention Diagram showing erasing characteristics of the optical recording medium according to Example 1 and the optical recording medium according to a comparative example having no Cr ₂ O ₃ interface layer Diagram showing erasing characteristics in the optical recording medium of Example 1 and the optical recording medium in which the recording film in Example 1 is changed to InSbTeGe The diagram which respectively shows the erasure | elimination characteristic of the optical recording medium of Example 1, and the comparative example which used InSbTeGeMn for the recording film of this optical recording medium FIG. 3 is a diagram showing a relationship between recording power and jitter value in the optical recording medium of Example 1; Diagram showing the erasing characteristics in the case of changing the thickness of the Cr ₂ O ₃ film in the optical recording medium of Example 2 was compared for each thickness Diagram showing the relationship between the Cr ₂ O ₃ film thickness and the rewritable maximum linear velocity in the optical recording medium of Example 2

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Optical recording medium 12 ... Board | substrate 14 ... 1st information layer 16 ... 2nd information layer (semi-transmissive information layer)
18 ... Recording film 20 ... Interface layer 22 ... Spacer layer 24 ... Light transmission layer

Claims (5)

A substrate, a first information layer provided on the light incident side of the laser beam in the substrate, and at least one semi-transmissive information layer provided on the light incident side further than the first information layer, Have
The semi-transmissive information layer includes a recording film and an interface layer provided adjacent to the light incident side of the recording film, and has a light transmittance of 30 to 80% with respect to the laser beam. , Sb, Ge as main components, NA of the objective lens and NA of the laser beam, where λ / NA ≦ 650 nm. An optical recording medium formed of ₂ O ₃ . In claim 1,
The optical recording medium, wherein the recording film has Sb of 70 at% to 94 at% and Ge of 5 at% to 21 at%. In claim 1 or 2,
The optical recording medium, wherein the recording film contains 1 at% or more and 10 at% or less with Mg as an additive component. In claim 1, 2 or 3,
An optical recording medium, wherein the interface layer has a thickness of 0.2 nm to 8 nm. In claim 1, 2 or 3,
An optical recording medium, wherein the interface layer has a thickness of 0.2 nm to 5 nm.

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