JP2001067720A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medium giving large signal amplitude and having excellent preservation durability and an erasing characteristic of a mark by forming a recording layer, which is used for recording, reproducing and erasing information by reversible phase transition between the amorphous phase and the crystal phase by irradiation with a laser beam having a specified wavelength or lower, and a first boundary layer from specified metal compounds respectively. SOLUTION: The recording layer of this optical recording medium, which is irradiated with the laser beam of 450 nm or lower and has a first inorganic protection layer, the first boundary layer, the recording layer and a second inorganic protection layer formed on a substrate in this order, is formed from the metal compound shown by the formula. In the formula, A is an element which is other than Ge, Sb and Te and selected from group 3A of the second period to group 6B of the sixth period of the periodic table of the elements; (x) satisfies 0.5<=(x)<=0.9; (y) satisfies 0.01<=(y)<=0.08 when (z) is 0 or 0.5<=(x)<=0.9; 0<=(y)<=0.08 when 0<(z)<=0.2. The first boundary layer is formed from carbon or a compound obtained by reacting the element selected from group 3A of the second period to group 6B of the sixth period with oxygen, carbon or nitrogen. This optical recording medium has large difference between the reflectance of the crystal phase and that of the amorphous phase when irradiated with the laser beam of 450 nm or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to
The present invention relates to an optical information recording medium capable of recording, erasing, and reproducing information. In particular, the present invention provides a method for erasing recorded information,
The present invention relates to a rewritable phase-change optical recording medium, such as an optical disk, an optical card, or an optical tape, having a rewritable function and capable of recording an information signal at high speed and high density.

[0002]

2. Description of the Related Art The technology of a conventional rewritable phase-change optical recording medium is as follows. These optical recording media have a recording layer mainly containing tellurium or the like, and at the time of recording, a focused laser light pulse is applied to the crystalline recording layer for a short time to partially melt the recording layer. The melted portion is quenched by thermal diffusion and solidified to form an amorphous recording mark. The light reflectance of this recording mark is lower than that of the crystalline state and can be reproduced optically as a recording signal. At the time of erasing, the recording mark is irradiated with a laser beam and heated to a temperature below the melting point of the recording layer and above the crystallization temperature to crystallize the amorphous recording mark and return to the original unrecorded state. .

[0003] Recording on these rewritable phase-change optical recording media
The material of the layer is Ge_TwoSb_TwoTe _FiveSuch as alloys (N.Yam
ada et al. Proc. Int. Symp. on Optical Memory 1987
 p61-66) are known. These Te alloys are used as a recording layer.
In the optical recording medium, the crystallization speed is high and the irradiation power is low.
High speed over with one circular beam just by modulating
Lighting is possible.

[0004] Japanese Patent No. 2903969 has a wavelength of 488 nm.
Using a laser, Ge_TwoSb_TwoTe _FiveOn the recording layer
The mark position is recorded at a mark interval of 1.17 μm, and the C / N
The technology that obtained 51dB and 49dB is disclosed.
You. This recording layer has low storage durability
Not only is not useful, but mark length is 0.4μm or less
Then, there is a problem that a practically sufficient C / N cannot be obtained.
there were.

[0005]

In an optical recording system using a laser having a wavelength of 450 nm or less, the sensitivity of the detector to the reproduction light is lower than that of the red light used in PDs and DVD-RAMs by one. / 2, the amplitude of the reproduced signal is greatly reduced, and the C / N is 4 to 8 dB.
Has also been problematic.

An object of the present invention is to provide a recording layer having a large signal amplitude and excellent storage durability of a mark because of a large difference in reflectance between a crystal and an amorphous material at 450 nm or less. It is an object of the present invention to provide a rewritable phase-change optical recording medium in which erasing characteristics are improved by using a layer.

[0007]

That is, according to the present invention, a laser beam having a wavelength of 450 nm or less is irradiated.
Recording, erasing, and reproducing of information are possible, and recording and erasing of information are performed by a reversible phase change between an amorphous phase and a crystalline phase, and at least a first inorganic protective layer and a recording layer are formed on a substrate. in the optical recording medium having a second inorganic protective layer in this order, said recording layer is represented by the following formula _{(I) {(Ge 0.5 Te} 0.5) x (Sb 0.4 Te 0.6) 1-x} 1-yz Sb y a z (I) (where A represents an element belonging to Groups 3A to 6B of the second to sixth periods in the periodic table of the element except for Ge, Sb, and Te, and x, y, and z represent numbers. And the following relational expressions are satisfied: 0.5 ≦ x ≦ 0.9, 0.01 ≦ y ≦ 0.08, z = 0
Or, 0.5 ≦ x ≦ 0.9, 0 ≦ y ≦ 0.08, 0
<Z ≦ 0.2, which is an optical recording medium.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies and found that a 450 n
m or less, the difference in reflectance between the crystal and the amorphous can be increased, and furthermore, by using a boundary layer made of a specific material not containing sulfide as a layer in contact with this, C / N, which is sufficiently large for practical use, It has been found that an optical recording medium that can be rewritten by storage stability of recording marks and rewritable by one-beam direct overwrite can be obtained.

That is, a typical layer structure of the constituent members of the optical recording medium in the present invention is such that a first inorganic protective layer, a carbon layer, a recording layer, a carbon layer, a second inorganic protective layer, and a reflective layer are formed on a transparent substrate. These are sequentially laminated. However, it is not limited to this.

The description will be made in the following order. A suitable material for the first inorganic protective layer is a film made of a mixture of ZnS and SiO ₂ . Since this material has a small residual stress, burst deterioration due to repeated overwriting is unlikely to occur. In addition, the mixture of ZnS, SiO _2, and carbon has a smaller residual stress in the film, and the recording sensitivity and the carrier-to-noise ratio (C
/ N) and the erasure rate is hardly deteriorated. The thickness of the film is determined by optical conditions, but is preferably from 5 to 500 nm. If the thickness is larger than this, cracks and the like may occur. If the thickness is smaller than this, the substrate is easily damaged by heat due to repetition of overwriting, and the repetition characteristics deteriorate. A particularly preferred range of the film thickness is from 10 nm to 200 nm.

In the present invention, it is necessary to provide a first boundary layer between the first inorganic protective layer and the recording layer described below. By providing this, a high erasing rate can be obtained, and one-beam direct overwriting can be performed. In addition,
This has the effect of preventing deterioration of jitter due to repetition of overwriting and reduction of the amplitude of the reproduced signal. It is presumed that the cause of this is that even if the recording layer is left for a long time, it is possible to prevent a change in the state of the recording layer such as the atomic arrangement and the reaction between the inorganic protective layer and the recording layer.

As the first boundary layer, (1) a substance obtained by combining oxygen with the element M1 belonging to the group 3A to 6B in the second to sixth periods in the periodic table of the element and oxygen, (2) the element period 6 from the 3A group of the 2nd to 6th period in the Ritsumei table
A substance formed by combining element B belonging to group B with carbon,
(3) 3 of the 2nd to 6th periods in the periodic table of the elements
It is necessary to use any of a substance obtained by combining nitrogen with the element M3 belonging to Group A to Group 6B and (4) carbon.

Among them, when stored for a long time with the recording layer,
Non-stoichiometric compounds of carbon, aluminum and oxygen, substances of chromium and nitrogen, substances of titanium and nitrogen, and non-stoichiometric compounds of germanium and nitrogen are preferred because peeling is unlikely to occur during repetition. .

When carbon is used for the boundary layer, the thickness is preferably 0.5 nm or more and 10 nm or less from the viewpoint of difficulty in peeling off from the first inorganic protective layer and optical conditions.
When the thickness exceeds 10 nm, it is easy to peel off from the first inorganic protective layer and the recording layer. On the other hand, when the thickness is less than 0.5 nm, it is difficult to deposit the film to a uniform thickness, and the effect of providing the carbon film may not be obtained. In view of the deposition rate of the carbon film, the thickness is particularly preferably 0.5 nm or more and 5 nm or less.
It is even more preferable that the thickness be 0.5 nm or more and 4 nm or less from the viewpoint of the repetition characteristics.

When the carbon film is formed by sputtering, the introduced gas may be a mixture of hydrogen as well as a rare gas such as Ar gas. Further, other materials may be mixed, but in order to obtain good characteristics, it is preferable that carbon is contained in a proportion of 60 mol% or more.

The composition of the recording layer of the present invention needs to be within the range of the following formula (I). _{{(Ge 0.5 Te 0.5) x} (Sb 0.4 Te 0.6) 1-x} in _{1-yz Sb y A z (} I) wherein, A is, Ge, Sb, from the second period in the Periodic Table of Elements except Te Elements belonging to Group 3A to Group 6B in the sixth period, that is, Al, Si, Sc, Ti, V, Cr,
Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge,
Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, C
d, In, Sn, La, Hf, Ta, W, Re, Ir,
It indicates at least one selected from Pt, Au, Tl, and Pb, x, y, and z indicate numbers and satisfy the following relational expression.

0.5 ≦ x ≦ 0.9, 0.01 ≦ y ≦ 0.
08, z = 0 or 0.5 ≦ x ≦ 0.9, 0 ≦ y ≦
If 0.08, 0 <z ≦ 0.2x <0.5, the contrast between the crystalline phase and the amorphous phase is too small, and a sufficient signal intensity may not be obtained. In some cases, the crystallization speed is reduced, the erasing characteristics are deteriorated, and one-beam direct overwriting may be difficult. When z = 0 and y <0.01, the stability of the amorphous is low, and the archival characteristics are poor. If y> 0.08, the initial erasing characteristics may be poor or the overwrite shelf may be poor. In the case of z> 0.2, the crystallization speed becomes slow, the erasing characteristics are deteriorated, one-beam direct overwriting becomes difficult, the repetition characteristics are largely deteriorated by phase separation, and the overwriting shelf is deteriorated. In the case of z = 0, the stability of the amorphous is low, and the archival characteristics may be deteriorated.

The thickness of the recording layer of the present invention is preferably 5 nm or more and 40 nm or less. When the thickness of the recording layer is smaller than the above, the recording characteristics are significantly degraded due to repeated overwriting, and when the recording layer is thicker than the above, the recording layer is likely to move due to repeated overwriting. Jitter becomes worse. In particular, when mark length recording is adopted, the recording layer is more likely to move due to recording and erasing than when pit position recording is used.To prevent this, it is necessary to further increase the cooling of the recording layer during recording. The thickness of the recording layer is preferably 7 nm.
To 35 nm, more preferably 7 nm to 25 nm.

The material of the second boundary layer of the present invention may be the same as the material of the first boundary layer, or may be a different material.

In the case where the second boundary layer is used, the crystallization speed of the recording layer becomes faster and the stability characteristics of the amorphous phase change as compared with the case where only the first boundary layer is used. .02 ≦ y ≦ 0.08 and z = 0, or 0 ≦ y ≦ 0.08 and 0.001 ≦ z ≦ 0.
It becomes 2. When z = 0 and y <0.02, the stability of the amorphous is low, and the archival characteristics are poor.
When y> 0.08, overwriting after long-term storage may be difficult. When z> 0.2, the crystallization speed becomes slow, the erasing characteristics deteriorate, and one-beam direct overwriting may become difficult.

The material of the second inorganic protective layer of the present invention may be the same as the material of the first inorganic protective layer, or may be a different material. The thickness is 2 nm or more and 5
0 nm or less is preferable. If the thickness of the second inorganic protective layer is smaller than the above, defects such as cracks are generated, and the durability of the second inorganic protective layer is undesirably reduced. On the other hand, if the thickness of the second inorganic protective layer is larger than the above, the cooling degree of the recording layer is undesirably low. The thickness of the second inorganic protective layer has a more direct effect on the cooling of the recording layer, and in order to obtain better erasing characteristics and repetitive durability, and particularly to achieve good recording in the case of mark length recording. .3 to obtain erasing characteristics
0 nm or less is more effective. Since it absorbs light and can be efficiently used as thermal energy for recording and erasing, it is also preferable to be formed from a non-transparent material. For example, a mixture of ZnS, SiO _2, and carbon has low residual stress in the film, and hardly causes deterioration in recording sensitivity, carrier-to-noise ratio (C / N), erasure rate, and the like even when recording and erasing are repeated. Is also preferred.

Examples of the material of the reflective layer include metals and alloys having light reflectivity, and mixtures of metals and metal compounds. Specifically, a metal having a high reflectivity, such as Al, Au, Ag, or Cu, an alloy containing the same as a main component, Al, S
Metal compounds such as nitrides, oxides, and chalcogenides such as i are preferable. Metals such as Al, Au, and Ag, and alloys containing these as main components are particularly preferable because of their high light reflectivity and high thermal conductivity. In particular, an alloy containing Al or Ag as a main component is preferable because the price of the material can be reduced. The thickness of the reflective layer is generally about 10 nm or more and 300 nm or less. The thickness is preferably 30 nm or more and 200 nm or less because the recording sensitivity is high and the reproduction signal intensity can be increased.

Next, a method for manufacturing the optical recording medium of the present invention will be described. As a method of forming a first inorganic protective layer, a first boundary layer, a recording layer, a second boundary layer, a second inorganic protective layer, a reflective layer, and the like on a substrate, a method of forming a thin film in a vacuum, for example, a vacuum deposition method , An ion plating method, a sputtering method and the like. In particular, the sputtering method is preferable because the composition and the film thickness can be easily controlled. The thickness of the recording layer or the like to be formed can be easily controlled by monitoring the deposited state with a quartz crystal film thickness meter or the like.

In addition, after forming the reflective layer, an inorganic protective layer such as ZnS, SiO ₂ , ZnS—SiO ₂ , or an ultraviolet curable resin is formed within a range that does not significantly impair the effects of the present invention. A protective layer such as a resin may be provided as necessary.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. (Analysis and Measurement Method) The compositions of the reflective layer and the recording layer were confirmed by ICP emission analysis (manufactured by Seiko Instruments Inc.).
The film thickness during the formation of the recording layer, the inorganic protective layer, and the reflective layer was monitored by a quartz oscillator film thickness meter. The thickness of each layer was measured by observing the cross section with a scanning or transmission electron microscope. The composition of the first boundary layer and the second boundary layer 2 is determined by Rutherford backscattering method (Nissin High Voltage Co., Ltd.)
Manufactured by AN-2500).

In the optical recording medium formed by sputtering, the recording layer on the entire surface of the disk was crystallized and initialized with a beam of a semiconductor laser having a wavelength of 830 nm before recording.

Next, an 8/16 modulated 3T signal was formed in the groove under the condition of a linear velocity of 4.4 m / sec using an optical head having a numerical aperture of the objective lens of 0.6 and a wavelength of 408 nm of the semiconductor laser. C / N was measured. At this time, the recording laser waveform used was a general multi-pulse. The window width at this time was 22.8 ns (the shortest mark length in this case was 0.3 μm). The decrease in the amplitude of the signal waveform and the presence or absence of a burst defect were observed with an oscilloscope.

(Example 1) thickness 0.6 mm, diameter 12c
m, 0.64 μm pitch (land width 0.32 μm, glue
Polycarbonate with spiral groove of 0.32μm)
While rotating the substrate made of carbonate at 30 revolutions per minute,
Went putter. First, 1 × 10^-3Pa
And then exhausted with SiO 2 in a 0.2 Pa Ar gas atmosphere.
_Two Is sputtered with ZnS added with 20 mol%
Then, a first inorganic protective layer having a thickness of 130 nm was formed. Then charcoal
A carbon target was sputtered to form a carbon layer of 2 nm.
Subsequently, an alloy target made of Ge, Sb, and Te was scanned.
Put on, thickness 12nm, composition Ge35.7Sb12.8Te
51.5 [that is, ｛(Ge_0.5Te_0.5)_0.729(Sb_0.4T
e_0.6)_0.271｝_0.98Sb_0.02Was obtained. further
A carbon layer is formed to a thickness of 2 nm as a second boundary layer, and a second inorganic protective layer is formed.
The same ZnS / SiO as the first inorganic protective layer as a layer _TwoThe spa
To form a 20 nm film, on which Al_97.5Cr
_2.5Sputtering alloy to form 100nm thick reflective layer
did. After removing this disk from the vacuum container,
Acrylic UV curable resin (Dainippon Ink) on the reflective layer
Spin-coated by SD-101 manufactured by Co., Ltd. and irradiated with ultraviolet rays
To form a resin layer having a thickness of 3 μm.
Using a slow-acting UV-effect resin using a clean printer
After coating and irradiating with ultraviolet light, a disk made in the same way
Two sheets were laminated to obtain an optical recording medium of the present invention.

When the C / N and the DC erasure rate were measured, they were 51 dB and 21 dB, respectively, and both were at practical levels.
/ N50 dB, which is sufficient to exceed the erasure rate of 20 dB at which one-beam direct overwrite is possible.
After standing for 100 hours at 90 ° C. and a relative humidity of 80% in the recorded state, the recorded signal was reproduced and the C / N was measured. As a result, there was no change at all. Also, no burst defects due to peeling were observed.

Example 2 The composition of the recording layer was Ge_36.2Sb
_10.9Te_52.5Nb_0.4[That is, ｛(Ge_0.5Te _0.5)
_0.729(Sb_0.4Te_0.6)_0.271｝_0.995Sb_0.001Nb
_0.004The same disc as in Example 1 was created except that
Made.

The measured C / N and DC erasure rates were 51 dB and 21 dB, respectively, which were higher than practical levels. After being left for 100 hours under the condition of 90 ° C. and 80% relative humidity in the recorded state, the recorded signal was reproduced,
When N was measured, there was no change at all. Also, no burst defects due to peeling were observed. Also, Nb
Instead of Al, Si, Sc, Ti, V, Cr, Mn,
Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Z
r, Mo, Ru, Rh, Pd, Ag, Cd, In, S
n, La, Hf, Ta, W, Re, Ir, Pt, Au,
Almost the same results were obtained when Tl and Pb were used.

Example 3 The composition of the recording layer was Ge _25.0 Sb
_21.6 Te _53.4 [i.e. _{{(Ge 0.5 Te 0.5) 0.} 51 (S
b _0.4 Te _0.6 ) _0.49 ｝ _0.98 Sb _0.02 ], and the same disk as in Example 1 was produced.

When the C / N and DC erasure rates were measured, they were 50 dB and 21 dB, respectively, which were higher than practical levels. After being left for 100 hours under the condition of 90 ° C. and 80% relative humidity in the recorded state, the recorded signal was reproduced,
When N was measured, there was no change at all. Also, no burst defects due to peeling were observed.

(Embodiment 4) The first boundary layer and the second boundary layer are A
A disk was produced in the same manner as in Example 1 except that the target was sputtered with a mixed gas of 16.7% oxygen and 63.3% argon to obtain Al ₂ O _2.50 having a thickness of 2 nm.

The measured C / N and DC erasure rates were 51 dB and 22 dB, respectively, which were higher than practical levels. After being left for 100 hours under the condition of 90 ° C. and 80% relative humidity in the recorded state, the recorded signal was reproduced,
When N was measured, there was no change at all. Also, no burst defects due to peeling were observed.

(Embodiment 5) The first boundary layer and the second boundary layer
A disk was produced in the same manner as in Example 1 except that the i target was sputtered with a mixed gas of 8.2% of nitrogen and 91.8% of argon to obtain TiN 0.87 having a thickness of 2 nm.

When the C / N and DC erasure rate were measured, they were 50 dB and 21 dB, respectively, which were higher than practical levels. After being left for 100 hours under the condition of 90 ° C. and 80% relative humidity in the recorded state, the recorded signal was reproduced,
When N was measured, there was no change at all. Also, no burst defects due to peeling were observed.

(Embodiment 6) The first boundary layer and the second boundary layer are C
A disk was prepared in the same manner as in Example 1 except that the r target was sputtered with a mixed gas of 28.6% of nitrogen and 71.4% of argon to obtain CrN 0.92 having a thickness of 2 nm.

When the C / N and DC erasure rates were measured, they were 51 dB and 20 dB, respectively, which were higher than practical levels. After being left for 100 hours under the condition of 90 ° C. and 80% relative humidity in the recorded state, the recorded signal was reproduced,
When N was measured, there was no change at all. Also, no burst defects due to peeling were observed.

(Embodiment 7) The first boundary layer and the second boundary layer
A disk was prepared in the same manner as in Example 1 except that the i target and the SiC target were simultaneously sputtered with argon gas to obtain a 2 nm thick SiC 0.85.

When the C / N and DC erasure rates were measured, they were 51 dB and 22 dB, respectively, which were higher than practical levels. After being left for 100 hours under the condition of 90 ° C. and 80% relative humidity in the recorded state, the recorded signal was reproduced,
When N was measured, there was no change at all. Also, no burst defects due to peeling were observed.

Comparative Example 1 The composition of the recording layer was Ge ₂ Sb ₂ T
e _{5 That, (Ge 0.5 Te 0.5) 0.444} (Sb 0. 4 Te
_0.6 ) A disc was produced in the same manner as in Example 1 except that the disc was changed to _0.556 .

When the C / N and DC erasure rates were measured, they were 45 dB and 18 dB, respectively, which were below the practical level. After being left for 100 hours under the condition of 90 ° C. and 80% relative humidity in the recorded state, the recorded signal was reproduced,
When N was measured, it was 43 dB, a decrease of 2 dB.

Comparative Example 2 The composition of the recording layer was GeTe, that is, (Ge _0.5 Te _0.5 ) _1.00 (Sb _0.4 Te _0.6 ) _0.00
A disc was produced in the same manner as in Example 1 except that the above conditions were satisfied.

When the C / N and DC erasure rates were measured, they were 51 dB and 15 dB, respectively. Although the C / N ratio was sufficient for practical use, the erasing rate was lower than the practical level.

Comparative Example 3 The composition of the recording layer was Ge _29.2 Sb
_28.7 Te _42.1 [that is, ｛(Ge _0.5 Te _0.5 )
Except that the _{0. 729 (Sb 0.4 Te 0.6)} 0.271} 0.8 Sb 0.2] was prepared the same disk as in Example 1.

The measured C / N and DC erasure rates were 50 dB and 10 dB, respectively. Although the C / N ratio was sufficient for practical use, the erasing rate was lower than the practical level.

[0048]

According to the optical recording medium of the present invention, the following effects can be obtained. (1) Practically sufficient C / N is obtained even in recording using a laser beam having a wavelength of 450 nm or less, and one-beam direct overwrite is possible. (2) Even if left for a long time after recording, there is no occurrence of burst defects and no disappearance of recording marks. (3) It can be easily manufactured by a sputtering method.

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Claims (4)

[Claims] An information recording, erasing, and reproducing operation can be performed by irradiating a laser beam having a wavelength of 450 nm or less, and the information recording and erasing can be performed in a reversible phase between an amorphous phase and a crystalline phase. In an optical recording medium having at least a first inorganic protective layer, a first boundary layer in contact with the recording layer, a recording layer, and a second inorganic protective layer in this order on a substrate, the recording layer is formed by the following formula (I) _{) {(Ge 0.5 Te 0.5)} x (Sb 0.4 Te 0.6) 1-x} 1-yz Sb y a z (I) ( wherein, a represents, Ge, Sb, second in the periodic table excluding Te The elements belonging to the groups 3A to 6B in the period from the sixth period to the sixth period are shown, x, y, and z are numbers and satisfy the following relational expressions: 0.5 ≦ x ≦ 0.9, 0.01 ≦ y ≦ 0.08, z = 0
Or, 0.5 ≦ x ≦ 0.9, 0 ≦ y ≦ 0.08, 0
<Z ≦ 0.2), and the first boundary layer is formed by combining (1) an element M1 belonging to Group 3A to Group 6B in the second to sixth periods in the periodic table of elements and oxygen. material,
(2) 3 of the second to sixth periods in the periodic table of the elements
A substance obtained by combining an element M2 belonging to Group A to Group 6B with carbon; (3) a second to sixth elements in the periodic table of the elements;
1. An optical recording medium comprising: a substance obtained by combining nitrogen with an element M3 belonging to Group 3A to Group 6B of the period and nitrogen; and (4) at least one selected from carbon. A second boundary layer which is in contact with the recording layer;
The second boundary layer, which is provided between the inorganic protective layer and the inorganic protective layer, is formed by combining (1) an element M1 belonging to Group 3A to Group 6B in the second to sixth periods of the periodic table of elements with oxygen. ,
(2) 3 of the second to sixth periods in the periodic table of the elements
A substance obtained by combining an element M2 belonging to Group A to Group 6B with carbon; (3) a second to sixth elements in the periodic table of the elements;
2. The optical recording medium according to claim 1, wherein the optical recording medium comprises at least one selected from the group consisting of a compound obtained by combining nitrogen with an element M3 belonging to the group 3A to group 6B and nitrogen. 3. The optical recording medium according to claim 1, wherein the first boundary layer and the second boundary layer are made of a substance containing carbon as a main component. 4. The optical recording medium according to claim 1, wherein said optical recording medium is used for recording a mark having a recording shortest mark length and / or a mark interval of 0.4 μm or less.