JP2002279689A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording medium dispensing with an initializing stage, having high shelf stability and applicable to a high density recording medium. SOLUTION: A lower dielectric layer 12, a crystallization promoting layer 13, a recording layer 14, an upper dielectric layer 15, a reflective radiation layer 16 and a protective layer 17 are successively laminated on a substrate 11. The crystallization promoting layer 13 is formed in <=5 nm massive film thickness from Bi and/or a Bi compound. The recording layer 14 is composed of Sb-Te-In. The composition ratio of In in the total composition of the crystallization promoting layer 13 and the recording layer 14 is not more than the composition ratio of Bi in the total composition of the crystallization promoting layer 13 and the recording layer 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a phase change recording type optical information recording medium.

[0002]

2. Description of the Related Art In recent years, optical information recording media have been actively researched and developed as means for recording, reproducing, and erasing an enormous amount of information. In particular, information recording and recording is performed by utilizing the fact that the recording layer reversibly changes phase between two states, crystalline and amorphous.
The so-called phase-change optical disk that performs erasing has the advantage that it is possible to simultaneously record new information while erasing old information only by changing the power of the laser beam (hereinafter referred to as "overwriting"). Is promising.

As a recording material for the overwriteable phase change type optical disc, an indium (In) -selenium (Se) alloy or In-antimony (Sb) -tellurium (L) having a low melting point and high laser beam absorption efficiency is used. Chalcogen alloys such as Te) and germanium (Ge) -Te-Sb alloys are mainly used.

In a normal phase-change type optical disk, the recording layer is irradiated with a laser beam having a recording power to heat the recording layer to a temperature equal to or higher than its melting point and then rapidly cooled, whereby the material of the recording layer becomes an amorphous state and the recording marks are formed. The recording layer material is crystallized by irradiating a laser beam having an erasing power to a temperature higher than the crystallization temperature and then gradually cooling, whereby the recording layer material is crystallized and the recording marks are erased.

[0005] Such a phase-change type optical disk is manufactured by sequentially forming a thin film constituting each layer on a substrate by a sputtering method, a vapor deposition method, or the like. Therefore, it is shipped after the entire surface is crystallized by irradiating a laser beam. This step is generally called an initialization step. However, this initialization step can be performed by the most efficient laser beam irradiation method.
3 to initialize the entire optical disc with a diameter of 120 mm
It takes about 0 seconds to 1 minute, which is the rate-determining stage in manufacturing an optical disc.

[0006] In order to shorten the time required for the initialization step and further to omit the initialization step itself, a method of providing a crystallization promoting layer on the surface of the recording layer on the substrate side has been developed.
In this method, the recording layer is formed on the crystallization promoting layer, and the crystallization promoting layer reduces the crystallization energy of the alloy constituting the recording layer, thereby facilitating crystallization. Thereby, when the recording layer is formed on the crystallization promoting layer,
The recording layer is crystallized to some extent or almost, so that the initialization time can be shortened or the initialization step can be omitted.

[0007] International Publication WO98 / 47142 discloses that a recording layer containing Ge-Sb-Te as a main component and a crystallization promoting layer containing bismuth (Bi) and / or a Bi compound as a main component are used. An optical information recording medium that does not substantially require an initialization step is disclosed. This utilizes Bi's high crystallization promoting action.

[0008]

However, the high crystallization promoting action of Bi conversely crystallizes a recording mark recorded in an amorphous state on a crystalline recording layer. Crystallization of the recording mark means erasure of the recorded information, which degrades the storage reliability. In this regard, the above-mentioned publication discloses Ge-S
A recording layer containing b-Te as a main component is used, and Ge having a low crystallization rate is used at 10 atomic% or more, so that deterioration of storage stability is suppressed. However, Ge with a low crystallization rate
Is a high-density recording medium, especially a DVD having a recording capacity exceeding 4.7 GB.
It is difficult to apply to such a recording medium.

As described above, the conventional optical information recording medium provided with the crystallization promoting layer composed of Bi can be applied to a high-density recording medium which does not require an initialization step and has high storage stability. It was not something.

In view of the above circumstances, it is an object of the present invention to provide an optical information recording medium which does not require an initialization step and has high storage reliability.

[0011]

In order to achieve the above object, an optical information recording medium according to the present invention comprises a crystallization promoting layer provided on a substrate, and a recording layer laminated on the crystallization promoting layer. And a phase-change optical information recording medium comprising:
The recording layer is mainly composed of antimony, tellurium, and indium, and the crystallization promoting layer is composed of bismuth or a bismuth compound, or an alloy mainly containing bismuth and a bismuth compound. The composition ratio of bismuth in the total atomic composition of the recording layer and the crystallization promoting layer is not more than the composition ratio of indium in the total atomic composition of the recording layer and the crystallization promoting layer. And

In the above structure, a phase-change recording type optical information recording device includes a recording layer composed of antimony, tellurium, and indium, and a crystallization promoting layer composed of bismuth and / or a bismuth compound. The medium is configured such that the composition ratio of indium in the overall composition of the recording layer and the crystallization promoting layer is equal to or less than the composition ratio of bismuth. Therefore, the erasure (crystallization) of a recording mark recorded as an amorphous state due to the high crystallization promoting effect of bismuth is
It can be suppressed by indium. This allows
An optical information recording medium having high storage reliability of recording marks can be obtained.

In the above structure, the thickness of the crystallization promoting layer has a mass thickness of 5 nm or less, and a composition ratio of indium in the total atomic composition of the recording layer and the crystallization promoting layer. Is preferably less than 7 atomic%.

That is, by using indium in the above range, the crystallization promoting effect of the bismuth and / or bismuth compound layer (crystallization promoting layer) provided with a mass thickness of 5 nm or less is suppressed, and high storage reliability is obtained. And get
High reproduction light stability can be maintained by suppressing the deterioration of reproduction light stability due to indium.

In the above structure, the thickness of the crystallization promoting layer has a mass thickness of 5 nm or less, and the composition of antimony in the total atomic composition of the recording layer and the crystallization promoting layer is: It is preferable that the content be 35 atomic% or more and 80 atomic% or less.

That is, by using antimony in the above range, it is possible to provide an optical information recording medium having a high composition ratio of antimony, suitable for a high-density recording medium, and having high storage stability.

In the above structure, the recording layer may have an atomic composition of 1 in the recording layer and the crystallization promoting layer.
Preferably, it contains less than 0 atomic% of germanium. Thereby, the storage stability of the optical recording information medium can be further improved.

In the above structure, it is preferable that the recording layer is substantially composed of a pseudo-binary eutectic containing antimony and tellurium as main components, and contains another element as an impurity.
That is, other elements such as indium are included in the recording layer constituent material as impurities.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical information recording medium according to an embodiment of the present invention will be described below with reference to the drawings. The optical information recording medium of the present embodiment uses antimony (Sb)-
It is provided with a recording layer containing tellurium (Te) -indium (In), and records and erases information by utilizing the fact that the recording layer reversibly changes between two states, crystalline and amorphous. It is a phase change type optical information recording medium.

FIG. 1 shows a configuration of an optical information recording medium according to the present embodiment. As shown in FIG. 1, an optical information recording medium 1
Are a substrate 11, a lower dielectric layer 12, and a crystallization promoting layer 1
3, a recording layer 14, an upper dielectric layer 15, a reflective heat radiation layer 16, and a protective layer 17.

The substrate 11 has, for example, a disk shape with an opening at the center and a diameter of 120 mm and a thickness of 0.6 mm. As a material forming the substrate 11, glass, ceramics, or resin can be used, and particularly, resin is preferable. Examples of the resin include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyethylene resin, polypropylene resin, silicone resin, fluorine resin,
ABS resin, urethane resin and the like can be mentioned. In particular, polycarbonate resin which is excellent in moldability, optical properties and cost is preferable.

On the surface of the substrate 11 on which the recording layer 14 is provided, a guide groove for tracking, a guide pit, and a preformat such as an address signal are formed.
The preformat is performed by directly molding the first substrate 1 upon injection molding or extrusion molding of a resin material such as polycarbonate.
1 is preferably formed.

The lower dielectric layer 12 is formed on the substrate 11. The lower dielectric layer 12 has a function of preventing deformation of the substrate due to heat during recording and erasing, and preventing oxidation of the recording layer and mass transfer or deformation along the guide groove. The lower dielectric layer 12 is made of a metal or a metal oxide, carbide, fluoride, sulfide or nitride, particularly zinc sulfide (Zn).
S) and a mixture (SiO ₂ ) of silicon oxide (SiO ₂ )
₂ content 20.5 mol%). The lower dielectric layer 12 is formed by various vapor deposition methods such as a vacuum deposition method, a sputtering method, a plasma CVD method, and a photo CVD method.
It is formed with a thickness of, for example, 50 nm to 500 nm by a method, an ion plating method, an electron beam evaporation method, or the like.

The crystallization promoting layer 13 is formed on the lower dielectric layer 12. The crystallization promoting layer 13 is made of bismuth (Bi) and / or a Bi compound. The crystallization promoting layer 13 has a function of reducing the crystallization energy of the alloy constituting the recording layer 14 and facilitating the crystallization of the recording layer 14. That is, the recording layer 14 formed in an amorphous state on the crystallization promoting layer 13 is crystallized after the film formation step. Thereby, at the end of the manufacturing process of the optical information recording medium 1, it is performed to crystallize the recording layer 14.
A so-called initialization step (usually a heating step) can be omitted. Therefore, the initialization step, which is the rate-determining step in the manufacturing process, can be omitted, and the manufacturing productivity can be improved.

The crystallization promoting layer 13 is formed by various vapor phase growth methods, for example, a vacuum deposition method, a sputtering method, and a plasma CVD method.
It is formed to a thickness of 5 nm or less in terms of mass film thickness, for example, 1 nm in thickness by a method, a photo CVD method, an ion plating method, an electron beam evaporation method or the like. The crystallization promoting layer 13
It is formed as a continuous film or a random island-shaped discontinuous film that does not limit the size and position of the region. The thickness of the crystallization promoting layer 13 may be any thickness as long as Bi can sufficiently obtain the effect of promoting crystallization of the recording layer 14, and is preferably as thin as possible. Further, the crystallization promoting layer 13 may contain an element other than Bi.

The recording layer 14 is formed on the crystallization promoting layer 13. The recording layer 14 is composed of an alloy containing antimony (Sb), tellurium (Te), and indium (In) as main components. Here, actually, the alloy constituting the recording layer 14 is a pseudo-binary eutectic of Sb and Te (Sb-Sb
₂ Te ₃ ) and contains other elements such as In as impurities.

The recording layer 14 can be formed by various vapor deposition methods, for example, a vacuum deposition method, a sputtering method, a plasma CVD method, a photo CVD method, an ion plating method, and an electron beam deposition method. The recording layer 14 is formed, for example, by sputtering with a target of Sb-Te-In alloy, for example, 10 nm to 100 nm, in particular,
It is formed with a mass thickness of 19 nm.

More specifically, the recording layer 14 contains Sb of 4
0 atomic% to 92 atomic%, Te is 15 atomic% to 6
It is composed of an alloy containing 0 atomic% or less and less than 7 atomic% of In.

Here, the atomic composition of the recording layer 14 is determined by the total atomic composition of the crystallization promoting layer 13 and the recording layer 14. That is, in the present embodiment in which the mass thickness of the crystallization promoting layer 13 is 5 nm or less, the composition of each element in the total composition of the crystallization promoting layer 13 and the recording layer 14 is such that Sb is 35 atomic% or more. It is specified that 80 atomic% or less, Te is 15 atomic% or more and 60 atomic% or less, and In is less than 7 atomic%. At this time, the atomic composition of Bi contained in the crystallization promoting layer 13 is
6 atomic% in the total composition of
It is as follows.

Sb is a composition ratio in the total composition of the crystallization promoting layer 13 and the recording layer 14, and is used in the range of 35 to 80 atomic%. Sb is a material having a high crystallization speed and suitable for high-density recording. Therefore, the optical information recording medium 1 provided with the recording layer 14 having the composition ratio in the above range has a high density recording medium, in particular, a D having a recording capacity exceeding 4.7 GB.
It is suitable for VD media.

However, when Sb is used at a high content in the recording layer 14, the recording marks recorded as amorphous are easily crystallized, and the storage reliability deteriorates. Therefore,
In order to prevent the storage reliability from deteriorating, Sb is deposited on the crystallization promoting layer 13.
80 atomic% in the total composition of
It is preferably used below. Conversely, when the composition ratio of Sb is low, a high crystallization rate of the recording layer 14 cannot be obtained, and it is desirable that the total composition of the two layers is 35 atomic% or more.

In is used at a composition ratio of less than 7 atomic% in the total composition of the crystallization promoting layer 13 and the recording layer 14. One of the purposes of incorporating In into the recording layer 14 is to suppress the crystallization promoting effect of Bi contained in the crystallization promoting layer 13. The high crystallization promoting effect of Bi promotes the crystallization of the recording layer 14 while deteriorating the storage stability of the recording mark recorded in the amorphous state. In is Bi
The deterioration of the storage reliability due to this is suppressed. In order to sufficiently obtain the storage stability retaining effect of In, the composition ratio of In in the overall composition of the crystallization promoting layer 13 and the recording layer 14 is equal to or less than the Bi composition ratio in the entire two layers, Preferably, it is not more than the composition ratio of Bi.

For example, when the optical information recording medium 1 is Bi and / or
Alternatively, a crystallization promoting layer 13 composed of a Bi compound and having a mass thickness of 5 nm and Sb (65 at%)-Te (29 at%)-
In the case where the recording layer 14 made of In (6 atomic%) and having a mass film thickness of 19 nm is provided, the composition ratio of Bi is 5.3 in the total composition of the crystallization promoting layer 13 and the recording layer 14. Atomic%, the composition ratio of In is 5.7%, and Bi
Is less than or equal to the In composition ratio. By setting the composition ratio of In higher than the composition ratio of Bi in this way, excessive crystallization of the recording layer 14 due to Bi is suppressed, and high storage reliability is obtained.

However, if the composition ratio of In to Bi is too high, the crystallization promoting effect of Bi cannot be sufficiently obtained. Therefore, In contains the crystallization promoting layer 13 and the recording layer 1.
It is preferable that Bi is contained in the recording layer 14 at a level substantially equal to or higher than the composition ratio of Bi in the overall composition of the recording layer 14, particularly, exceeding the Bi composition ratio. Therefore, Sb and T
When the thickness of the recording layer 14 containing e as the main component is 5 nm (the composition ratio of Bi in the composition of the entire two layers is 6 atomic% or less), In causes the crystallization promoting layer 13 and the recording layer 14 It is preferable to use a composition of less than 7 atomic% in the total composition.

Te is a composition ratio in the whole composition of the crystallization promoting layer 13 and the recording layer 14 and is used in a range of 15 at% to 60 at%. Te is used to form a stable recording layer 14 and to adjust the composition ratio of other elements, such as Sb, In, and Bi.

The recording layer 14 may contain other elements or impurities for improving the reliability and the like. Examples of impurities that can be added to the recording layer 14 include boron, phosphorus, selenium, aluminum, titanium, vanadium, iron, cobalt, nickel, palladium, germanium, platinum, and gold.

Of the above elements, germanium is particularly preferably added because it improves storage reliability. However, germanium lowers the crystallization speed of the recording layer 14 and is not suitable for a high-density recording medium such as 4.9 GB. Therefore, in order to form the recording layer 14 having high crystallinity and high storage reliability and applicable to a high-density recording medium, germanium is contained in the entire crystallization promoting layer 13 and the recording layer 14 in total. Preferably, it is added at less than atomic%.

The upper dielectric layer 15 is formed on the recording layer 14. The upper dielectric layer 15 can be formed using the same material and the same method as the lower dielectric layer 12. The upper dielectric layer 15 is formed with a thickness of, for example, 20 nm.

The reflection heat dissipation layer 16 is formed on the upper dielectric layer 15. The reflective heat radiation layer 16 is provided for the purpose of improving the reflectance at the time of reproducing information and radiating the heat applied at the time of recording and erasing. The reflective layer 15 may be made of a metal, a metal compound, or the like that can provide a high reflectance by itself and is not easily corroded.
l), a high-reflectivity metal such as a simple substance such as gold, silver, platinum, copper, and titanium, or an alloy containing at least one of these, or
These alloys, for example, an aluminum-titanium alloy can be used.

The reflective heat radiation layer 16 is formed by using various kinds of vapor deposition methods, for example, a vacuum deposition method, a sputtering method, a plasma CVD method, a photo CVD method, an ion plating method, using a target made of, for example, Al among the above materials. Can be formed by an electron beam evaporation method or the like. The reflective heat dissipation layer 16 is provided with a thickness of, for example, 140 nm.

The protective layer 17 is provided on the reflective heat radiation layer 16. The protective layer 17 is provided for the purpose of physically and chemically protecting the recording layer 14 and the like, or for the purpose of improving the reflectance. Examples of the material used for the protective layer 17 include inorganic materials such as silicon oxide, magnesium fluoride, tin oxide, and silicon nitride, or polymethyl acrylate, polycarbonate, epoxy resin, polystyrene,
Organic resin materials such as polyester resin, vinyl resin, cellulose, aliphatic hydrocarbon resin, aromatic hydrocarbon resin, natural rubber, styrene butadiene resin, chloroprene rubber, wax, alkyd resin, drying oil and rosin can be exemplified. The protective layer 17 is, for example, 0.01 μm to 3 μm.
It is provided with a thickness of 0 μm. The protective layer 17 includes a stabilizer,
A dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, a plasticizer and the like can be contained.

The protective layer 17 can be formed, for example, by laminating a film obtained by extrusion of a plastic on the reflective heat radiation layer 16. Alternatively, it may be provided by a method such as vacuum deposition, sputtering, or coating. In the case of a thermoplastic resin or a thermosetting resin, they can also be formed by dissolving these in an appropriate solvent to prepare a coating solution, applying the coating solution, and drying. In the case of a UV curable resin, a coating solution is prepared as it is or dissolved in an appropriate solvent,
It can also be formed by applying this coating solution and irradiating it with UV light to cure it. Various additives such as an antistatic agent, an antioxidant, and a UV absorber may be added to these coating solutions according to the purpose.

In this embodiment, the optical information medium 1
Are a substrate 11, a lower dielectric layer 12, and a crystallization promoting layer 1
3, the recording layer 14, the upper dielectric layer 15, the reflective heat dissipation layer 16, and the protective layer 17,
It may be configured to include other necessary layers.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples unless it exceeds the gist.

In the following Examples 1 to 3, film formation was performed using a single-wafer sputtering apparatus having five chambers. However, the number of chambers is not limited to five, and a film forming apparatus having six or more chambers may be used. The film forming conditions in each chamber are shown below. (First chamber) Target material: SiO ₂ (20.5 mol%), ZnS
(79.5 mol%) Input power: RF 4 kW / 8 inch (120 mm) target, Gas pressure: 2 mTorr Gas type: Ar Film thickness: 190 nm (second chamber) Target material: Bi Input power: DC 0.4 kW / 8 inch target, Gas pressure: 2 mTorr Gas type: Ar Film thickness: 1 nm, 0.5 nm (third chamber) Target material: Sb-Te-In and other elements Input power: DC 0.4 kW / 8 inch target, Gas pressure: 2 mTorr Gas type : Ar film thickness: 19 nm (fourth chamber) Target material: SiO ₂ (20.5 mol%), ZnS
(79.5 mol%) Input power: RF 4 kW / 8 inch target, gas pressure: 2 mTorr Gas type: Ar Film thickness: 20 nm (fifth chamber) Target material: Al Input power: DC 5 kW / 8 inch target, gas pressure: 2 mTorr gas Species: Ar Film thickness: 140 nm

(Example 1) A diameter 120c was obtained by injection molding.
m, a substrate 1 made of polycarbonate having a thickness of 0.6 mm
Form one. The formed substrate 11 is carried into the sputtering apparatus, and first, in the first chamber, the lower electrode layer 1 is formed.
2 (ZnS—SiO ₂ ) is formed to a thickness of 190 nm. Next, in the second chamber, the crystallization promoting layer 13 is formed.
(Bi) is formed into a film with a thickness of 1 nm. Next, in the third chamber, the recording layer 14 (Sb-Te-In) was
m to form a film. Next, in the fourth chamber, the upper dielectric layer 15 (ZnS—SiO ₂ ) is formed with a thickness of 20 nm. Finally, in the fifth chamber, a reflective heat dissipation layer 16 (Al) is formed with a thickness of 140 nm. After that, the substrate is carried out of the sputtering apparatus, spin-coated with an ultraviolet curable resin, and then irradiated with ultraviolet light to form the protective layer 17.

In the optical information recording medium 1 manufactured as described above, the recording layer 14 has the following five compositions (I-1).
To 5). In each case, the total composition of the crystallization promoting layer 13 and the recording layer 14 is In.
The composition ratio and the Bi composition ratio (both in atomic%) are shown in parentheses. (I-1) Sb: Te: In = 66: 33: 1 (each atomic%) (Bi 5.3 atomic%, In 0.95 atomic%) (I-2) Sb: Te: In = 66: 31: 3 (Each atom%) (Bi 5.3 atom%, In 2.9 atom%) (I-3) Sb: Te: In = 66: 29: 5 (each atom%) (Bi 5.3 atom%, In 4.8 atom %) (I-4) Sb: Te: In = 65: 29: 6 (atomic%) (Bi 5.3 atomic%, In 5.7 atomic%) (I-5) Sb: Te: In = 65: 28 : 7 (atomic%) (Bi 5.3 atomic%, In 6.7 atomic%)

The five types of optical information recording media 1 (I-1 to I-1)
For 5), the storage reliability was examined. Evaluation is 0.6m
Recording was performed with a laser beam in the state of m single plate, and the storage reliability at 80 ° C. was examined. Specifically, the various types of optical information recording media 1 (I-1 to 5) have a disk rotation speed of 3.5 m / m.
s, under a recording condition of 26.7 MHz, a laser beam (63
Recording pulse ratio of 5 nm, NA 0.6) and recording jitter of 7
% (Σ / Tw), and the time required for the jitter to become 8% when stored at 80 ° C. was examined. Table 1 shows the results
Shown in In Table 1, the composition ratio (atomic%) of each element is based on the overall composition of the crystallization promoting layer 13 and the recording layer 14.

[Table 1]

As shown in Table 1, when the In composition ratio is half or less than the Bi composition ratio (I-1 and 2), 1
From 0 hr to 20 hr, the jitter exceeded 8%, indicating that the storage reliability was low enough to be unpractical. On the other hand, when the Bi composition ratio and the In composition ratio become 4.8 atomic%, which are almost the same (I-3), the time to reach the jitter of 8% is 100 hr, and the storage reliability is rapidly improved. Further, In
When the composition ratio exceeds 5.7 atomic% and the Bi composition ratio, the storage reliability is further improved and reaches up to 180 hours. Furthermore, even when the In composition ratio is 6.7 atomic%, which is 1% or more higher than the Bi composition ratio (I-5), stable high storage reliability is obtained.

From the above results, when the crystallization promoting layer 13 containing Bi as a main component and having a mass thickness of 5 nm or less is used (the Bi composition ratio in the overall composition of the crystallization promoting layer 13 and the recording layer 14 is (6 atomic% or less), it can be seen that high storage reliability can be obtained by using In at a composition ratio equal to or higher than Bi in the overall composition of the crystallization promoting layer 13 and the recording layer 14. . Also, in this case, In
It is understood that it is preferable to use at least 3 atomic% and not more than 7 atomic%.

(Example 2) Diameter 120c by injection molding
m, a substrate 1 made of polycarbonate having a thickness of 0.6 mm
Form one. The formed substrate 11 is carried into the sputtering apparatus, and first, in the first chamber, the lower electrode layer 1 is formed.
2 (ZnS—SiO ₂ ) is formed to a thickness of 190 nm. Next, in the second chamber, the crystallization promoting layer 13 is formed.
(Bi) is formed into a film with a thickness of 1 nm. Next, in the third chamber, the recording layer 14 (Sb-Te-In or Sb-
Te-In-Ge) is deposited to a thickness of 19 nm. Next, in the fourth chamber, the upper dielectric layer 15 (ZnS
—SiO ₂ ) is deposited to a thickness of 20 nm. Finally, in the fifth chamber, the reflective heat dissipation layer 16 (Al) is
The film is formed with a thickness of nm. After that, the substrate is carried out of the sputtering apparatus, spin-coated with an ultraviolet curable resin, and then irradiated with ultraviolet light to form the protective layer 17.

In the optical information recording medium 1 manufactured as described above, the recording layer 14 has the following three compositions (II-
1-3). In each case, the total composition of the crystallization promoting layer 13 and the recording layer 14
The n composition ratio (atomic%) is shown in parentheses. (II-1) Sb: Te: In = 65: 29: 6 (atomic%) (In 5.7 atomic%) (II-2) Sb: Te: In = 65: 27.6: 7.4 (each Atomic%) (In 7.0 atomic%) (II-3) Sb: Te: In: Ge = 65: 26: 6: 3 (atomic%) (In 5.7 atomic%)

The three types of optical information recording medium 1 (II-1)
For (3), storage reliability (reproduction light reliability) was examined. For evaluation, recording was performed with a laser beam in a 0.6 mm single plate state, and storage reliability at 80 ° C. was examined. More specifically, the laser light (635 nm, NA 0.6) is applied to the various optical information recording media 1 (II-1 to 3) under recording conditions of a disk rotation speed of 3.5 m / s and 26.7 MHz. The irradiation pulse ratio was adjusted so that the recording jitter was 7% (σ / Tw), and the reading laser power at which the jitter during reproduction 10,000 times was 8% or less was examined. Table 2 shows the results. In Table 2, the In composition ratio (atomic%) is based on the overall composition of the crystallization promoting layer 13 and the recording layer 14.

[Table 2]

From the results shown in Table 2, the recording layer 14 (II-3) to which 3 atomic% of Ge was added was not added (II-1).
It can be seen that the reproduction light stability is improved as compared with the case of FIG. This indicates that storage reliability can be improved by adding Ge. However, if the composition ratio of Ge is too high, the crystallinity of the recording layer 14 is deteriorated. Therefore, it is preferable that Ge is contained in less than 10 atomic% in the entire composition of the crystallization promoting layer 13 and the recording layer 14.

When In is contained at 7 atomic% or more in the total composition of the crystallization promoting layer 13 and the recording layer 14 (II-2), the reproduction light stability is so low that it cannot be practically used. Therefore, it is understood that In is desirably less than 7 atomic% in the total composition of the crystallization promoting layer 13 and the recording layer 14 for the purpose of suppressing a decrease in storage reliability due to Bi. From the results of the storage stability test in Example 1, when the crystallization promoting layer 13 made of Bi was used at 5 nm or less, the composition ratio of In in the entire composition of the crystallization promoting layer 13 and the recording layer 14 was determined. Is preferably not less than 3 atomic% and less than 7 atomic%.

(Example 3) A diameter of 120c was obtained by injection molding.
m, a substrate 1 made of polycarbonate having a thickness of 0.6 mm
Form one. The formed substrate 11 is carried into the sputtering apparatus, and first, in the first chamber, the lower electrode layer 1 is formed.
2 (ZnS—SiO ₂ ) is formed to a thickness of 190 nm. Next, in the second chamber, the crystallization promoting layer 13 is formed.
(Bi) is deposited to a thickness of 0.5 nm. Next, in the third chamber, the recording layer 14 (Sb-Te-In or Sb-Te-In
(b-Te-In-Ge) is deposited to a thickness of 19 nm.
Next, in the fourth chamber, the upper dielectric layer 15 (Zn
(S-SiO ₂ ) is formed to a thickness of 20 nm. Finally,
In the fifth chamber, the reflective heat dissipation layer 16 (Al)
The film is formed with a thickness of 0 nm. Thereafter, the substrate is carried out of the sputtering apparatus, and after spin-coating with an ultraviolet curable resin, the protective layer 17 is formed by irradiating with ultraviolet light.

In the optical information recording medium 1 manufactured as described above, the recording layer 14 has the following three compositions (III).
-1 to 3). In each case, the Sb composition ratio (atomic%) in the entire composition of the crystallization promoting layer 13 and the recording layer 14 is shown in parentheses. (III-1) Sb: Te: In = 66: 31: 3 (atomic%) (Sb 57.5 atomic%) (III-2) Sb: Te: In = 75: 22: 3 (atomic%) ( (Sb 65.4 atomic%) (III-3) Sb: Te: In = 93: 7: 3 (each atomic%) (Sb 81.5 atomic%)

The above three types of optical information recording media 1 (III-
Regarding 1 to 3, the storage reliability (reproduction light reliability) was examined. For evaluation, recording was performed with a laser beam in a 0.6 mm single plate state, and storage reliability at 80 ° C. was examined. More specifically, the laser light (635 nm, NA 0.6) is applied to the various optical information recording media 1 (III-1 to 3) under a recording speed of 3.5 m / s and 26.7 MHz. The irradiation pulse ratio was adjusted so that the recording jitter was 7% (σ / Tw), and the reading laser power at which the jitter during reproduction 10,000 times was 8% or less was examined. Table 3 shows the results.
In Table 3, the composition ratio (atomic%) of Sb is based on the total composition of the crystallization promoting layer 13 and the recording layer 14.

[Table 3]

As can be seen from Tables III-1 and II, as the composition ratio of Sb in the recording layer 14 increases,
It can be seen that the storage reliability of the optical information recording medium 1 decreases. However, if the composition ratio of Sb in the overall composition of the crystallization promoting layer 13 and the recording layer 14 is about 65 atomic% or more,
The time required for the jitter to reach 8% is 200 hours or more,
It can be seen that sufficiently high storage reliability can be obtained.

However, when the composition ratio of Sb reaches 81.5 atomic% (III-3), the time until the jitter reaches 8% is sharply reduced to 50 hours, and the storage reliability is reduced to such an extent that it cannot be practically used. are doing. From this, the crystallization promoting layer 1
The composition ratio of Sb in the overall composition of No. 3 and the recording layer 14 is as follows:
From the viewpoint of storage reliability, the content is preferably 80 atom% or less. On the other hand, in order to obtain high crystallization characteristics of the recording layer 14, the composition ratio of Sb is preferably as high as possible, and the preferable composition ratio of Sb in the overall composition of the crystallization promoting layer 13 and the recording layer 14 is as follows: 35 to 80 atomic% (40 to 92 atomic% in the recording layer 14).

As can be seen from Examples 1 to 3, according to the present embodiment, the crystallization promoting layer 13 containing Bi
In an optical information recording medium including a recording layer 14 composed of b, Te, and In, the composition ratio of Bi in the overall composition of the crystallization promoting layer 13 and the recording layer 14 is substantially the same as the composition ratio of In, or It is less than that. Thereby, deterioration of storage reliability of the recording layer 14 due to Bi is suppressed, and the optical information recording medium 1 with high storage reliability is provided.

For example, when the crystallization promoting layer 13 has a thickness of 5 nm or less and the total composition of the crystallization promoting layer 13 and the recording layer 14 is about 6 atom%, Has a composition ratio of about 7 atomic%. At this time, high storage stability of the recording layer 14 is obtained.

The recording layer 14 of this embodiment contains 35 to 80 atomic% of Sb in the overall composition.
S is a material suitable for a high-density recording medium of 4.7 GB or more.
By setting the composition ratio of b in the above range, a recording layer 14 having high storage reliability and applicable to a high-density recording medium can be obtained.

Further, the alloy constituting the recording layer 14 may contain Ge at a composition ratio of 10 atomic% or less. Thereby, storage reliability can be improved. here,
The recording layer 14 is a pseudo-binary eutectic composed of Sb and Te, and Ge and In are contained in the recording layer 14 as impurities.

[0065]

According to the present invention, there is provided an optical information recording medium having a high storage reliability in which the initialization step can be omitted.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an optical information recording medium according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 optical information recording medium 11 substrate 12 lower dielectric layer 13 crystallization promoting layer 14 recording layer 15 upper dielectric layer 16 reflective heat dissipation layer 17 protective layer

Continued on the front page (72) Inventor Nobuaki Onagi 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Masato Hariya 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. F-term (reference) 2H111 EA04 EA23 EA40 FA11 FA23 FA24 FB05 FB09 FB12 FB21 5D029 JA01 JB03 JB35

Claims (5)

[Claims] An optical information recording medium of a phase change type comprising: a crystallization promoting layer provided on a substrate; and a recording layer laminated on the crystallization promoting layer. , Tellurium, and indium, and composed of an alloy containing as a main component, and the crystallization promoting layer is composed of at least one of bismuth and a bismuth compound as a main component, and the recording layer and the crystallization promoting layer The optical information recording medium according to claim 1, wherein the composition ratio of bismuth in the total atomic composition of indium is not more than the composition ratio of indium in the total atomic composition of the recording layer and the crystallization promoting layer. 2. The film thickness of the crystallization promoting layer has a mass thickness of 5 nm or less, and the composition ratio of indium in the total atomic composition of the recording layer and the crystallization promoting layer is 7%.
2. The optical information recording medium according to claim 1, wherein the content is less than atomic%. 3. The film thickness of the crystallization promoting layer has a mass thickness of 5 nm or less, and the total atomic composition of the recording layer and the crystallization promoting layer is 35% antimony.
The optical information recording medium according to claim 1, wherein the optical information recording medium has a content of at least 80 atomic%. 4. The recording layer according to claim 1, wherein said recording layer contains less than 10 atomic% of germanium in the total atomic composition of said recording layer and said crystallization promoting layer. An optical information recording medium according to claim 1. 5. The optical information according to claim 1, wherein the recording layer is made of a pseudo-binary eutectic containing antimony and tellurium as main components, and contains another element as an impurity. recoding media.