JP2007076309A - Optical recording medium and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phase-change type optical recording medium, the recording layer of which consists of a recording material mainly composed of Sb and one element except Sb, and which is excellent in shelf life and the degree of modulation. <P>SOLUTION: In this phase-change type optical recording medium, at least a first protective layer, the recording layer, a second protective layer and a reflecting layer are provided on a substrate in this order or reverse order; electromagnetic-wave irradiation causes a reversible change between a crystal phase and an amorphous phase on the recording layer; and at least the recording and reproduction of information are performed by utilizing the optical change. The phase-change type optical recording medium, the recording layer of which consists of the recording material mainly composed of SB and one element except SB, is characterized by satisfying the condition: a polycrystal state after initialization is mainly composed of a cubic phase in such a manner that a diffraction peak exists in the range of a diffraction angle 2θ of 27-31° in an X-ray diffraction method in which a CuK alpha ray serves as an X-ray source. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rewritable phase change optical recording medium that records and reproduces information at least by irradiating a light beam to cause an optical change in a recording layer made of a phase change material.

Each layer of a conventional phase change optical recording medium is often produced by sputtering, and a rare gas such as Ar gas is often used as a sputtering gas in order to avoid unnecessary reactions in each layer. Thereby, an optical recording medium can be produced relatively stably and inexpensively. However, this method has problems such as the sensitivity of the optical recording medium being low and the optical recording medium being significantly deteriorated due to poor storage characteristics.
With respect to these problems, Patent Document 1 discloses that an optical recording medium is prepared by adding nitrogen to sputtering gas Ar, and Patent Document 2 discloses that a sputtering gas (Ar is used when forming a recording layer). It has been proposed to add hydrogen to).

In the former case, by adding nitrogen to the sputtering gas, the crystallization transition temperature is increased, the thermal stability is ensured and the storage characteristics are improved, and the main components (Ag, In, Sb, Te) used for the recording layer are improved. ) Is appropriately set, the rate of optical change between the crystal part and the non-crystal part can be increased to improve the sensitivity. However, this method is suitable for a recording material composed of Ag, In, Sb, and Te having a large composition ratio of Sb and Te, but is composed mainly of In and Sb (the composition ratio of In and Sb is It is not suitable for recording materials (larger than other constituent elements).
In the latter case, by adding hydrogen to the sputtering gas, crystallization from the amorphous phase can be easily performed, and long-term storage characteristics can be improved, and the recording layer thickness is set appropriately. By doing so, it is possible to suppress the deterioration of recording characteristics due to repeated overwriting and to reduce jitter. However, the most effective recording material capable of obtaining the above effect is a Pd—Nb—Ge—Sb—Te alloy, which contains In and Sb as main components (the composition ratio of In and Sb is higher than that of other constituent elements). There is no description or suggestion about the case of using a recording material.

JP 2002-92953 A JP 2002-182286 A

  An object of the present invention is to provide a phase change type optical recording medium in which the recording layer is composed of a recording material mainly composed of one element other than Sb and Sb, and has excellent storage characteristics and modulation.

The above problems are solved by the following inventions 1) to 8).
1) At least a first protective layer, a recording layer, a second protective layer, and a reflective layer are provided on the substrate in this order or in the reverse order, and a reversible phase change between a crystalline phase and an amorphous phase is caused in the recording layer by irradiation with electromagnetic waves. In the phase change type optical recording medium in which information is recorded and reproduced at least by utilizing the optical change, the recording layer is composed of a recording material mainly composed of one element other than Sb and Sb, A phase change optical recording medium characterized by satisfying the following conditions.
(conditions)
In the X-ray diffraction method using CuKα rays as an X-ray source, the polycrystalline state after initialization has a diffraction peak at a diffraction angle 2θ of 27 ° to 31 ° and is mainly composed of a cubic phase. .
2) The phase change optical recording medium according to 1), wherein one element other than Sb has a number of electrons of 5p orbit in an electronic state of an atom of 3 or less and belongs to a period smaller than the fifth period. .
3) The phase change optical recording medium according to 2), wherein one element other than Sb is any one of In, Ga, Ge, and Sn.
4) The phase change optical recording medium according to 3), wherein one element other than Sb is In, and the composition ratio of In and Sb satisfies the following condition.
0.1 <In / Sb <0.35
5) The phase change optical recording medium according to any one of 1) to 4), wherein one element other than Sb is bonded to hydrogen.
6) The phase change optical recording medium according to any one of 1) to 5), wherein the recording material satisfies the following conditions in its infrared absorption spectrum.
(conditions)
When an amorphous phase of the recording material is formed on the Si substrate under the same conditions as the production of the recording layer of the optical recording medium and the film thickness is changed to 1000 mm, infrared absorption spectrum measurement is performed from the recording material on the Si substrate. In the measurement using the GATR (Thermo Electron Co., Ltd.) accessory in the ATR method, an absorption peak is observed at 1500 to 1600 cm ⁻¹ .
7) Any one of 1) to 6) including a recording layer formed using a mixed gas of Ar gas and hydrogen gas as a sputtering gas and having a gas pressure ratio satisfying the following formula: The phase change optical recording medium described.
0.04 ≦ hydrogen gas pressure / Ar gas pressure ≦ 0.12
8) The phase change optical recording medium according to 7), wherein a mixed layer of Ar gas and hydrogen gas is used as the sputtering gas, and the recording layer is formed under a condition that the gas pressure ratio satisfies the following formula: Production method.
0.04 ≦ hydrogen gas pressure / Ar gas pressure ≦ 0.12

Hereinafter, the present invention will be described in detail.
As described above, it is known to improve the characteristics by adding another gas to the rare gas as the sputtering gas, but the main component is In and Sb (the composition ratio of In and Sb is another constituent element). There is no literature on recording materials. As a result of various studies, the present inventors have succeeded in improving the medium characteristics by using a mixed gas of Ar gas and hydrogen gas as the sputtering gas.
The preferred gas pressure ratio is as follows. By controlling the composition ratio of hydrogen gas, an optimal amount of In—H bonds can be formed in the recording layer.
0.04 ≦ hydrogen gas pressure / Ar gas pressure ≦ 0.12
When hydrogen is bonded to In, the following actions (1) and (2) occur.

(1) Ensuring sufficient modulation and storage reliability in long-term storage.
For example, in the In atom and the Sb atom, the Sb atom has more electrons because the number of electrons is larger. Therefore, the bonds between In atoms with few bonds and Sb atoms with many bonds are not balanced as a whole and exist in an unstable state. This unstable state is also reflected in the electronic state of the crystalline phase and the amorphous phase, resulting in the amorphous phase of the crystalline phase, the crystallization of the amorphous phase, etc., and the difference in reflectance between the recorded portion and the unrecorded portion. This will reduce the modulation depth. Further, since it is in an unstable state, when thermal energy is applied as in a storage test, the amorphous structure and the crystal structure change, which affects the storage reliability of the recording medium.
These problems are caused by bonding a hydrogen atom having an electron donating property and a reducing action to atoms other than Sb such as In, which is a main component of the recording material, together with Sb, so that electrons of atoms other than Sb with a small number of electrons are present. This can be solved by stabilizing the electronic state and stabilizing the structure by making the electronic states of Sb atoms and atoms other than Sb closer and maintaining the balance of the number of bonds.

The above effect appears when the polycrystalline state after initialization is mainly composed of cubic crystals.
X-ray diffraction shows that there are six atoms around one atom forming a cubic crystal such as NaCl type. The Sb atom has three electrons in the 5p orbital, so it can be bonded by px _{, y, and z.} However, since the In atom has only one electron in the 5p orbital, by supplementing the electrons in the 5p orbital, the structure Stability is improved.
That is, in order to bring the electronic states of Sb atoms and atoms other than Sb closer to each other and maintain the balance of the number of bonds, the number of electrons in the 5p orbit of atoms other than Sb needs to be smaller than the number of electrons in the 5p orbit of Sb. In addition, it is necessary to select an energy whose 5p orbit is lower than Sb. Therefore, the elements having the above effects are limited to those having the number of electrons in the 5p orbital of 3 or less and a cycle shorter than Sb. If the period is larger than that of the Sb element, the energy level of the 5p orbit is increased, which is not suitable for coupling.
Examples of elements other than In that have a bonding effect with hydrogen include Ga, Ge, and Sn.

(2) Sensitivity improvement by increasing the optical change rate of the crystal part and the non-crystal part.
When a recording material containing In and Sb as main components is used for the recording layer, the composition ratio of In and Sb is preferably in the following range. This is because the effect of hydrogen also depends on the amount of In.
0.1 <In / Sb <0.35
When 0.1 or less, the amount of In decreases, so the effect of In—H bonding decreases. When 0.35 or more, a ZnS-type crystal structure of In / Sb = 1: 1 is precipitated in a high-temperature storage test. Therefore, it is not preferable.
This makes it possible to increase the optical change rate between the crystal part and the non-crystal part, and to increase the CN ratio of the reproduction signal. Moreover, high sensitivity recording peculiar to InSb-based materials can be effectively realized.

Next, the configuration of the optical recording medium of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration example of a phase change optical recording medium of the present invention. A first protective layer 2, a recording layer 3, a second protective layer 4, a third protective layer 5, and a reflective layer 6 are formed on a substrate 1. Is provided.
The recording layer is preferably made of a material having a composition ratio of In and Sb larger than that of other constituent elements. However, a material having a composition ratio of Ga and Sb, Ge and Sb, or Sn and Sb larger than those of other constituent elements may be used. it can.
The thickness of the recording layer is 6 to 22 nm, preferably 8 to 18 nm. Outside this range, it is not preferable because it causes a decrease in recording sensitivity and a decrease in repetition characteristics.

The first, the second protective _{layer, SiOx, ZnO, SnO 2,} Al 2 O 3, TiO 2, In 2 O 3, MgO, ZrO 2, metal oxides such as _{Ta 2 O 5; Si 3 N} 4, Examples thereof include nitrides such as AlN, TiN, BN, and ZrN; sulfides such as ZnS and TaS ₄ ; and carbides such as SiC, TaC, B ₄ C, WC, TiC, and ZrC. These materials may be used alone or as a mixture. For example, examples of the mixture include ZnS and SiOx, Ta ₂ O ₅ and SiOx. Material physical properties to be considered when using these materials as the first and second protective layers include thermal conductivity, specific heat, thermal expansion coefficient, refractive index, and adhesion to the substrate material or recording layer material. It is required that the melting point is high, the coefficient of thermal expansion is small, and the adhesion is good.
The second protective layer stores the heat applied to the recording layer by irradiating the laser beam during recording, while transferring the heat to the reflective layer and releasing the heat. To do. According to the knowledge of the present inventors, it is preferable to use a mixture of ZnS and SiO ₂ for the second protective layer.

The thickness of the first protective layer is 50 to 250 nm, preferably 75 to 200 nm. If it is thinner than 50 nm, the environmental resistance protection function and heat resistance are lowered, which is not preferable. If it is thicker than 250 nm, it is not preferable because film peeling or cracking occurs due to an increase in the film temperature in the film forming process by sputtering or the like, and the sensitivity during recording is lowered.
The thickness of the second protective layer is 4 to 100 nm, preferably 4 to 50 nm, and more preferably 4 to 30 nm. If it is thinner than 4 nm, the heat resistance basically decreases, which is not preferable. If the thickness exceeds 100 nm, the overwrite characteristics are repeatedly deteriorated due to a decrease in recording sensitivity, film peeling due to temperature rise, deformation, and a decrease in heat dissipation.

In the present invention, the reflective layer serves as a light reflective layer, and also serves as a heat dissipation layer that releases heat applied to the recording layer by laser light irradiation during recording. Since the formation of the amorphous mark greatly depends on the cooling rate by heat dissipation, the selection of the reflective layer is particularly important in the medium corresponding to the high linear velocity.
Although it is preferable to use Au, Ag, Al, and an alloy containing these as a main component for the reflective layer, it is more preferable to use Ag having a very high thermal conductivity or an alloy containing Ag as a main component. Thereby, the cooling rate can be increased and the recording sensitivity can be improved.
The thickness of the reflective layer is preferably 100 to 300 nm. Since the heat dissipation capability of the reflective layer is basically proportional to the thickness of the layer, if it is less than 100 nm, the cooling rate decreases, which is not preferable. Moreover, when it exceeds 300 nm, the increase in material cost will be caused.

In the case where a reflective layer made of Ag or an alloy containing Ag as a main component is provided in contact with the second protective layer, when the second protective layer is made of a material containing sulfur, in order to avoid the generation of pinholes due to the sulfurization of Ag , between the reflective layer and the second protective layer, Si, SiC, SiN, GeN, etc. ZrO _2, it is preferable to provide a third protective layer containing no sulfur as a barrier layer. Among these, Si and SiC are particularly preferable in that the effect of barriering sulfur is high.
The thickness of the third protective layer is 2 to 20 nm, preferably 2 to 10 nm. If it is less than 2 nm, it does not function as a barrier layer, and if it exceeds 20 nm, the recording sensitivity is lowered.

  According to the first to eighth aspects of the present invention, it is possible to provide a phase change optical recording medium having excellent storage characteristics and good modulation degree, and a method for manufacturing the same.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited at all by these Examples, Production conditions can also be changed suitably.

Example 1
A grooved polycarbonate disk substrate having a diameter of 12 cm, a thickness of 0.6 mm, and a track pitch of 0.74 μm is dehydrated at a high temperature and then sputtered to form a first protective layer, a recording layer, a second protective layer, a third protective layer, and a reflective layer Were sequentially formed.
The first protective layer was a ZnS · SiO ₂ target and had a thickness of 65 nm.
The recording layer was sputtered using an alloy target having a composition of In ₂₂ Sb ₇₈ at an argon gas pressure of 3 × 10 ⁻³ Torr, a hydrogen gas pressure of 0.24 × 10 ⁻³ Torr, and an RF power of 300 mW. It was.
Similar to the first protective layer, the second protective layer was made of a ZnS · SiO ₂ target and had a thickness of 7 nm.
The third protective layer was made of a SiC target and had a thickness of 4 nm.
The reflective layer was a pure silver target and had a thickness of 120 nm.
Next, an organic protective film made of an acrylic UV curable resin is applied on the reflective layer by a spinner to a thickness of 5 to 10 μm, and then UV cured, and then a polycarbonate disk having a diameter of 12 cm and a thickness of 0.6 mm is bonded to the adhesive sheet. The recording layer was initially crystallized by irradiation with a large-diameter LD beam to obtain a phase change optical recording medium.

Example 2
A grooved polycarbonate disk substrate having a diameter of 12 cm, a thickness of 0.6 mm, and a track pitch of 0.74 μm is dehydrated at a high temperature and then sputtered to form a first protective layer, a recording layer, a second protective layer, a third protective layer, and a reflective layer Were sequentially formed.
The first protective layer was a ZnS · SiO ₂ target and had a thickness of 65 nm.
The recording layer was sputtered using an alloy target having a composition of In ₁₀ Sb ₉₀ at an argon gas pressure of 3 × 10 ⁻³ Torr, a hydrogen gas pressure of 0.24 × 10 ⁻³ Torr, and an RF power of 300 mW. It was.
Similar to the first protective layer, the second protective layer was made of a ZnS · SiO ₂ target and had a thickness of 7 nm.
The third protective layer was made of a SiC target and had a thickness of 4 nm.
The reflective layer was a pure silver target and had a thickness of 120 nm.
Next, an organic protective film made of an acrylic UV curable resin is applied on the reflective layer by a spinner to a thickness of 5 to 10 μm, and then UV cured, and then a polycarbonate disk having a diameter of 12 cm and a thickness of 0.6 mm is bonded to the adhesive sheet. The recording layer was initially crystallized by irradiation with a large-diameter LD beam to obtain a phase change optical recording medium.

Example 3
A grooved polycarbonate disk substrate having a diameter of 12 cm, a thickness of 0.6 mm, and a track pitch of 0.74 μm is dehydrated at a high temperature and then sputtered to form a first protective layer, a recording layer, a second protective layer, a third protective layer, and a reflective layer Were sequentially formed.
The first protective layer was a ZnS · SiO ₂ target and had a thickness of 65 nm.
The recording layer was sputtered using an alloy target having a composition of In ₂₂ Sb ₇₈ at an argon gas pressure of 3 × 10 ⁻³ Torr, a hydrogen gas pressure of 0.09 × 10 ⁻³ Torr, and an RF power of 300 mW. It was.
Similar to the first protective layer, the second protective layer was made of a ZnS · SiO ₂ target and had a thickness of 7 nm.
The third protective layer was made of a SiC target and had a thickness of 4 nm.
The reflective layer was a pure silver target and had a thickness of 120 nm.
Next, an organic protective film made of an acrylic UV curable resin is applied on the reflective layer by a spinner to a thickness of 5 to 10 μm, and then UV cured, and then a polycarbonate disk having a diameter of 12 cm and a thickness of 0.6 mm is bonded to the adhesive sheet. The recording layer was initially crystallized by irradiation with a large-diameter LD beam to obtain a phase change optical recording medium.

Example 4
A grooved polycarbonate disk substrate having a diameter of 12 cm, a thickness of 0.6 mm, and a track pitch of 0.74 μm is dehydrated at a high temperature and then sputtered to form a first protective layer, a recording layer, a second protective layer, a third protective layer, and a reflective layer Were sequentially formed.
The first protective layer was a ZnS · SiO ₂ target and had a thickness of 65 nm.
Recording _layer, using an alloy target having a composition of an In 40 _{Sb 60,} an argon gas pressure of 3 × ¹⁰ -3 Torr, a hydrogen gas pressure of 0.45 × ¹⁰ -3 Torr, and sputtered with RF power 300 mW, thickness 16nm It was.
Similar to the first protective layer, the second protective layer was made of a ZnS · SiO ₂ target and had a thickness of 7 nm.
The third protective layer was made of a SiC target and had a thickness of 4 nm.
The reflective layer was a pure silver target and had a thickness of 120 nm.
Next, an organic protective film made of an acrylic UV curable resin is applied on the reflective layer by a spinner to a thickness of 5 to 10 μm, and then UV cured, and then a polycarbonate disk having a diameter of 12 cm and a thickness of 0.6 mm is bonded to the adhesive sheet. The recording layer was initially crystallized by irradiation with a large-diameter LD beam to obtain a phase change optical recording medium.

Comparative Example 1
A grooved polycarbonate disk substrate having a diameter of 12 cm, a thickness of 0.6 mm, and a track pitch of 0.74 μm is dehydrated at a high temperature and then sputtered to form a first protective layer, a recording layer, a second protective layer, a third protective layer, and a reflective layer Were sequentially formed.
The first protective layer was a ZnS · SiO ₂ target and had a thickness of 65 nm.
The recording layer was sputtered at an argon gas pressure of 3 × 10 ⁻³ Torr and RF power of 300 mW using an alloy target having a composition of In ₂₂ Sb ₇₈ to a film thickness of 16 nm.
Similar to the first protective layer, the second protective layer was made of a ZnS · SiO ₂ target and had a thickness of 7 nm.
The third protective layer was made of a SiC target and had a thickness of 4 nm.
The reflective layer was a pure silver target and had a thickness of 120 nm.
Next, an organic protective film made of an acrylic UV curable resin is applied on the reflective layer by a spinner to a thickness of 5 to 10 μm, and then UV cured, and then a polycarbonate disk having a diameter of 12 cm and a thickness of 0.6 mm is bonded to the adhesive sheet. The recording layer was initially crystallized by irradiation with a large-diameter LD beam to obtain a phase change optical recording medium.

  Infrared absorption spectra and X-ray diffraction spectra were measured for the optical recording media of the above examples and comparative examples, and the degree of modulation and storage characteristics were evaluated. The results are shown in Table 1.

<Measurement method of infrared absorption spectrum>
A sample in which only the film thickness was changed to 1000 mm and an amorphous recording material layer was formed on a Si substrate under the same conditions as those for forming the recording layer was used. The sample chamber of the apparatus was purged with dry nitrogen to minimize the influence of water vapor and carbon dioxide.
As the apparatus, FT-IR Avatar 370 (Thermo Electron Co., Ltd.) was used.
-Measurement condition-
・ Measurement method: ATR method ・ Accessories: GATR (for single reflection ATR, Ge, ultra-thin film)
・ Detector: MCT-A
・ Resolution: 4cm ^-1
Atmosphere: _{N 2}
-Wave number range: 5000-800 cm ^-1
・ Number of integration: 256 times ・ Sample film thickness: 1000 mm
<Infrared absorption peak of In-H>
As an example of the measurement result of the infrared absorption spectrum, the case of Example 1 and Comparative Example 1 is shown in FIG. 2 that Example 1 has an absorption peak at 1500 to 1600 cm ⁻¹ although it is very wide and weak. The reason why the width of the peak is wide and weak is thought to be because various In—H bonds exist because it is amorphous. Comparative Example 1 does not have such a peak. The peak on the lower wavenumber side than 1300 cm ⁻¹ is absorption by the Si substrate.
The position of infrared absorption due to the bond of In—H is described in the document H. Himmel et al; Am. Chem. Soc. (2002), 124, 4448-4457.

<Measurement method of X-ray diffraction spectrum>
The recording layers remaining on the polycarbonate substrate were used as measurement samples from the phase change optical recording medium prepared and initialized with the film thicknesses described in the examples, with the vicinity of the second and third protective layers as a boundary. As the X-ray diffractometer, an X'pert MRD manufactured by Philips was used. A tube voltage of 45 kV and a tube current of 40 mA are applied, Cu Kα rays are generated from a tube bulb having a Cu target, and parallel X-rays are 0.5 ° with respect to the sample surface using a reflection mirror in the incident optical system. Incident at an angle. X-rays diffracted from the sample pass through a 0.27 ° collimator and enter the detector. The detector side was scanned at 2θ, and measurement was performed by an asymmetric reflection method (thin film X-ray diffraction method) using a parallel beam.
<Initialized crystal>
The measurement results of the X-ray diffraction spectra of Example 1 and Example 2 are shown in FIG.
Example 1 is a NaCl-type cubic crystal, but Example 2 is completely different from Example 1 in diffraction pattern and is hexagonal.

<Evaluation of modulation factor>
In order to see the correspondence to high density and high linear velocity recording, the recording linear velocity and the recording power are 3.5 m / s (15 mW), 17 m / s (20 mW), and 35 m / s, respectively, at a recording density of 0.267 μm / bit. Overwriting was repeated with an EFM random pattern at s (28 mW), 56 m / s (38 mW), a recording laser wavelength of 650 nm, and the modulation degree of the 14T signal was examined as an evaluation of the reproduction signal characteristics.
When the degree of modulation was 60% or more, ◎, when 50-60%, ◯, and 50% or less, Δ.
<Evaluation of preservation test>
The storage reliability was evaluated by the jitter value of the 3T signal for the first overwrite after each optical recording medium was held at 80 ° C. and 85 RH% for 100 hours.
A decrease in jitter value of 0 to 3% was evaluated as ◎, 3 to 8% as ％, and 8% or more as ×.

As a result, the storage characteristics of Examples 1, 3, and 4 in which absorption peaks of stretching vibrations of In and hydrogen were observed in infrared absorption were good, and Example 1 was particularly good. In Example 2, since the crystal structure is a hexagonal crystal, the effect caused by bonding of hydrogen to In is reduced, and the degree of modulation is worse than that in Examples 1, 3, and 4.

The figure which shows the structural example of the phase change type | mold optical recording medium of this invention. The figure which shows the infrared absorption spectrum of Example 1 and the comparative example 1. FIG. The figure which shows the X-ray-diffraction spectrum of Example 1 and Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 1st protective layer 3 Recording layer 4 2nd protective layer 5 3rd protective layer 6 Reflective layer

Claims (8)

Having at least a first protective layer, a recording layer, a second protective layer, and a reflective layer on the substrate in this order or in the reverse order, an electromagnetic wave irradiation causes a reversible phase change between a crystalline phase and an amorphous phase in the recording layer, In a phase-change optical recording medium in which at least information is recorded and reproduced using the optical change, the recording layer is composed of a recording material mainly composed of one element other than Sb and Sb. A phase change optical recording medium characterized by satisfying the conditions.
(conditions)
In the X-ray diffraction method using CuKα rays as an X-ray source, the polycrystalline state after initialization has a diffraction peak at a diffraction angle 2θ of 27 ° to 31 ° and is mainly composed of a cubic phase. .   2. The phase change optical recording medium according to claim 1, wherein one element other than Sb has a number of electrons in a 5p orbit in an electronic state of an atom of 3 or less and belongs to a period smaller than the fifth period.   3. The phase change optical recording medium according to claim 2, wherein one element other than Sb is any one of In, Ga, Ge, and Sn. 4. The phase change optical recording medium according to claim 3, wherein one element other than Sb is In, and the composition ratio of In and Sb satisfies the following condition.
0.1 <In / Sb <0.35   5. The phase change optical recording medium according to claim 1, wherein one element other than Sb is bonded to hydrogen. 6. The phase change optical recording medium according to claim 1, wherein the recording material satisfies the following conditions in its infrared absorption spectrum.
(conditions)
When an amorphous phase of the recording material is formed on the Si substrate under the same conditions as the production of the recording layer of the optical recording medium and the film thickness is changed to 1000 mm, infrared absorption spectrum measurement is performed from the recording material on the Si substrate. In the measurement using the GATR (Thermo Electron Co., Ltd.) accessory in the ATR method, an absorption peak is observed at 1500 to 1600 cm ⁻¹ . The mixed gas of Ar gas and hydrogen gas is used as a sputtering gas, and the recording layer is formed under a condition that the gas pressure ratio satisfies the following formula: Phase change type optical recording medium.
0.04 ≦ hydrogen gas pressure / Ar gas pressure ≦ 0.12 8. The production of the phase change optical recording medium according to claim 7, wherein a mixed layer of Ar gas and hydrogen gas is used as the sputtering gas, and the recording layer is formed under a condition that the gas pressure ratio satisfies the following formula. Method.
0.04 ≦ hydrogen gas pressure / Ar gas pressure ≦ 0.12

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