JP2712060B2 - Rewritable optical information recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording of information,
To enable you to perform reproducing and erasing, so-called rewritable optical information recording medium (hereinafter, simply referred to as optical media.) A relates improvements in repetitive durability of recording and erasing, the protective film adjacent to the recording layer To provide new materials.

[0002]

2. Description of the Related Art A phase in which a reversible structural change (phase change) between an amorphous state and a crystalline state of a substance caused by light irradiation, mainly laser light irradiation, is actively used for recording information. The rewritable optical information recording medium has a large recording capacity in addition to a high-speed information processing capability, and is expected as a future information storage device.

[0003] As the speed of information processing becomes even more severe in this optical medium, the performance of erasing information recorded at high speed at higher speed is required. On the other hand, a so-called stable operation of repetition of recording / erasing, in which once recorded information is erased and another information is further recorded thereon, is indispensable. The stable operation of this repeated recording / erasing is at least 10 ⁵
Need more than one time.

[0004]

The recording / erasing repetition characteristics of an optical medium strongly reflect the properties of a recording film material and a protective film material. In a recording film material, a change in volume before and after recording / erasing, phase separation, and the like cause deterioration of the recording / erasing repetitive characteristics. For example, it is known that a Ge-Te-Sb ternary recording film material in which Sb is slightly excessive in the compound composition on the line connecting GeTe and Sb ₂ Te ₃ has excellent recording / erasing repetition characteristics. However, even if a recording film material having excellent recording / erasing repetition characteristics is used, good recording / erasing repetition characteristics are not necessarily obtained by using only the recording film material. Play an important role in improving For the protective film material, the residual stress, particle size, heat resistance, adhesion to the recording film, and the like affect the recording / erasing repetition characteristics. For example, SiO ₂ or ZnS intended to increase the residual stress recording and erasing repetition operation is greatly reduced and used in the protective film, but equal to or less than 10 ⁵ times, if as low as possible residual stress 10 ⁵ times about The recording / erasing repetition operation can be performed stably. However, it was not easy to perform recording and erasing repetition operation to reach 10 ⁶ times stably.

[0005] The present inventors have Ttei Tomah durability of recording and erasing repetition operation of the phase change type optical medium is affected by various characteristics of the protective layer adjacent to the recording film of about 10 ⁵ times
Particular attention that, as a result of intensive studies from the point of view of the new protective film material for the improved method, the present invention has been completed. sand
That is, the present invention improves the durability of the recording / erasing repeated operation.
To provide a rewritable optical information recording medium
And

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and can be realized by taking the following means. That is, in the base material of the protective layer adjacent to the recording film, at least of the constituent elements of the recording film 1
The solution is achieved by including various types of elements. More specifically, in the rewritable optical information recording medium according to the present invention, in claim 1, a reversible phase transition between an amorphous state and a crystalline state of a recording film is caused by light irradiation, and In a rewritable optical information recording medium capable of recording and erasing data, the constituent elements of the recording film are Ge, Te, Sb, B
i, a 5 element Se, and a protective layer adjacent to the recording layer contains at least one element that make up the recording film on the base material. A rewritable optical information recording medium which causes a reversible phase transition between an amorphous state and a crystalline state of a recording film by light irradiation, thereby enabling recording and erasing of information. The film is composed of five elements Ge, Te, Sb, Bi, and Se, and the base material of the protective film adjacent to the recording film is made of an oxide. According to a third aspect, in the first or second aspect, the base material of the protective film adjacent to the recording film is made of SiO, SiO.
₂ , Al ₂ O ₃ , and Ta ₂ O ₅ . According to a fourth aspect, in the first, _second and _third aspects, the base material of the protective film is SiO, SiO ₂ , Al.
_When at least one of the five elements constituting the recording film is contained in the base material, the content of the constituent elements of the recording film contained in the protective film is made of at least one of ₂ O ₃ and Ta ₂ O _5. The amount is in the range of 4 to 22 mol%. According to a fifth aspect, in the first to fourth aspects, the base material of the protective film is made of at least one of SiO, SiO ₂ , Al ₂ O ₃ , and Ta ₂ O ₅ , and the recording film is formed in the base material. When one kind of element is included, the content of the recording film constituent element contained in the protective film is in a range of 4 to 15 mol%. According to a sixth aspect, in the first to fifth aspects, the base material of the protective film is SiO, SiO ₂ , Al.
_When at least one element of ₂ O ₃ and Ta ₂ O ₅ is contained in the base material and the five elements constituting the recording film are contained, the content of the recording film material constituting element contained in the protective film is 13%. ~ 2
It is characterized by being in the range of 2 mol%. Claim 7
Constitutes a recording film in a rewritable optical information recording medium which causes a reversible phase transition between an amorphous state and a crystalline state of the recording film by light irradiation, thereby enabling information recording and erasing. to that element Ge, a 3 element Te and Sb, the base material of the protective layer adjacent to the recording film SiO, Si
It is characterized by comprising at least one of O ₂ , Al ₂ O ₃ , and Ta ₂ O ₅ . In a preferred embodiment, the base material of the protective film is SiO, SiO ₂ , Al _2.
When at least one of Ge, Te, Sb, Bi, and Se is included in the base material, the protective film includes at least one of O ₃ and Ta ₂ O _5. Characterized in that the content of the element contained in is in the range of 4 to 22 mol%. Claim 9 is Claim 7 or 8
In the above, the base material of the protective film is SiO, SiO ₂ , Al ₂ O
_3, consisting of at least one of _Ta 2 _{O 5,} Ge in the base material, when moistened Te, Sb, Bi, one type of 5 elements Se, contained in the protective layer of the five elements Characterized in that the content of the selected element is in the range of 4 to 15 mol%. According to a tenth aspect, in the seventh or eighth aspect, the base material of the protective film is SiO, SiO ₂ , Al ₂ O ₃ , T
a ₂ O ₅ and at least one of G
When five elements e, Te, Sb, Bi and Se are included,
The content of the five elements contained in the protective film is 13 to 22.
It is characterized by being in the range of mol%.

[0007]

The recording film is composed of Ge, Te, Sb, Bi, and Se.
The ternary system or the ternary system of Ge, Te, and Sb, in which at least one of the constituent elements of the recording film is contained in the base material of the protective film adjacent to the recording film, the details are sufficiently clear. However, in particular, the adhesion between the recording film and the protective film is increased, and the durability of the recording / erasing repeated operation can be improved.

[0008]

Embodiment 1 FIG. 1 shows an example of the configuration of an optical medium according to the present invention. Transparent substrate 1
1, a protective film 12, a recording film 13, a protective film 14, and a metal film 15 are sequentially laminated. The transparent substrate 11 is made of a glass substrate that has been sufficiently cleaned, and is formed of a protective film 12 and a protective film 1.
4 was made of SiO ₂ containing the constituent elements of the recording film, and the metal film 15 was made of an Al alloy. The substrate material is not limited to glass, but may be any material that can be used. For example, a resin such as polycarbonate or PMMA can be used. Protective film 12 and protective film 14
The thickness of the metal film 15 is 120 nm and 20 nm, respectively.
nm and about 100 nm. The recording film 13 has G
e, Te, Sb, Bi and Se as the constituent elements, and ｛(GeTe) ₂ [(Sb-Bi) ₂ (Te-S
e) ₃ ] ₁ } _1−x · Sbx, X = 0.6, Bi = 4.
4 at% and Se = 4.4 at% were used. The thickness of the recording film 13 was about 20 nm. Protective film 12, protective film 14, recording film 13, and metal film 14
Were formed by all high-frequency magnetron sputtering methods. In particular, the protective film is a SiO ₂ target and a recording film.
The film was formed by preparing a target composed of at least one of the following constituent elements and forming a film by a dual simultaneous sputtering method, or by preparing and sputtering a composite target. The film forming method is not limited to the high-frequency magnetron sputtering method, and includes, for example, a DC sputtering method, a vacuum evaporation method, a spin coating method, and a plasma C method.
Any method capable of forming a film, such as a VD method, may be used. The composition of the recording film was confirmed by photoelectron spectroscopy, and the composition of the protective film was confirmed by EDAX.

As shown in FIG. 2, the recording / erasing repetition characteristic in the stationary state is such that the optical head 2 comprises a laser light source having a wavelength of 830 nm and an objective lens having a numerical aperture of about 0.52.
The laser beam 22 is applied to the recording film 1 from the glass substrate 11 side.
3 was examined by focusing and irradiating a laser beam 22. Prior to the measurement of the recording / erasing repetition characteristics, initial crystallization was performed on the recording film 13 by laser annealing or heat treatment without melting the recording film. When performing the heat treatment, the surface of the metal film 15 is further protected by a protective film (approximately 100
nm). Recording is signal contrast, C
To The contrast was set at about 30% and the recording pulse width was fixed at 50 ns. For erasure, set the erase pulse width to 10
The test was performed at a constant value of 0 ns.

FIG. 3 shows the relationship between the measured number of recording / erasing repetitions and the content of the recording film material (same composition as the recording film) contained in the base material of the SiO ₂ protective film. Although recording film materials SiO _2, recording and erasing repetition count when not containing were those stops 10 ⁵ times, the content of the recording film material 13-2
If it is in the range of 2 mol%, the number of recording / erasing repetitions is 1
The effect of improving in more than 0 ⁵ times was observed. The content of the recording film material may if desired in the range of 16 ~ 20 mol%, were this time can be obtained recording and erasing repetition count of more than 10 ⁶ times. Although the details of the increase in the number of recording / erasing repetitions are not clear, it is considered that the adhesion between the recording film and the protective film is increased. The fact that the number of recording / erasing repetitions decreases as the content of the recording film in the protective film increases seems to be related to the increase in the absorption of laser light in the protective film. Here, the protective film containing the recording film material does not necessarily need to be adjacent to both sides of the recording film, and any one may be used as long as the effect can be obtained.

[0011] recording film material contained in the protective film is not necessarily the same composition as the recording film, further at least one Exceeded in recording and erasing repetition count of <br/> constituent elements of the recording film What is necessary is just a content which can improve. For example, in any case where the recording film contains Bi or Se, or a recording film material excluding both Bi and Se, the number of recording / erasing repetitions can be increased within the same content range as described above. Was. Further, GeTe, Sb ₂
Even when a material composed of two kinds of constituent elements of the recording film , such as Te ₃ or Bi ₂ Te ₃ , was included, it was possible to increase the number of recording / erasing repetitions within the same content range as described above. When Sb, which is one of the constituent elements of the recording film material, is contained in SiO _2, it is recorded that the content is in the range of about 4 to 15 mol% as shown in FIG.
The effect of improving the number of erase repetitions can be enhanced. Desirably sufficient if the range of 7~13mol%, were this time can be obtained recording and erasing repetition count of more than 10 ⁶ times. In addition, substantially the same effect was obtained when the constituent elements of the recording film other than Sb were used.

Example 2 Example 1 was the same as Example 1 except that SiO ₂ was used instead of SiO ₂ for the base material of the protective film. When the same components as in the recording film composition were included, the measurement results were the same as in FIG. When recording film material to SiO protective film base material has not been contained, the recording and the recording and erasing repetition count were those stops 10 ⁵ times, the content of the recording film material is in the range of 13～22Mol%, erasing the number of repetitions was observed the effect of improvement in more than 10 ^five times. The content of the recording film material is desirably in the range of 16 to 20 mol%.
^Six or more recording / erasing repetitions were obtained. Further, the material contained in the base material of the protective film is not limited to the same composition as that of the recording film , but may be composed of at least one or more of the constituent elements of the recording film , and the same effects as in Example 1 were obtained.

Example 3 The procedure of Example 1 was repeated except that Al ₂ O ₃ was used instead of SiO ₂ as the base material of the protective film. The measurement results were the same as in Example 1 as shown in FIG. Al ₂ when O ₃ recording film material in the protective film base material has not been contained, the recording and erasing repetition count is were those stops 10 ⁵ times, the content of the recording film material is in the range of 13～22Mol% recording and erasing repetition number of times and it was found to the effect of improving in more than 10 ^five times.
The content of the recording layer material desirably may to be in the range of 16~20mol%, at this time could be obtained recording and erasing repetition count of more than 10 ⁶ times. Further, the material contained in the base material of the protective film is not limited to the same composition as that of the recording film , but may be composed of at least one or more of the constituent elements of the recording film , and the same effects as in Example 1 were obtained.

Example 4 The procedure of Example 1 was repeated except that Ta ₂ O ₅ was used instead of SiO ₂ as the protective film base material. FIG. 6 shows the measurement results. When the same components as in the recording film composition were contained, the measurement results were as good as in FIG. When the recording film material was not contained in the base material of the Ta ₂ O ₅ protective film, the number of recording / erasing repetitions was limited to ⁵ 10 times, but the content of the recording film material was in the range of 13 to 22 mol%. recording and erasing the number of repetitions was observed the effect of improvement in more than 10 ^five times. The content of the recording film material, preferably 16~20m
well to be in the range of ol%, at this time could be obtained recording and erasing repetition count of more than 10 ⁶ times. further,
The material contained in the base material of the protective film is not limited to the same composition as that of the recording film, and may be made of at least one or more constituent elements of the recording film , and the same effects as in Example 1 were obtained.

[0015]

As described above, according to the present invention, the recording film has a five-element structure of Ge, Te, Sb, Bi, and Se with respect to the recording / erasing repetition durability of the phase-change optical medium. System or G
The adhesion between the recording film and the protective film is increased by using a ternary system of e, Te, and Sb and by including at least one or more of the constituent elements of the recording film in the base material of the protective film adjacent to the recording film. Thus, the recording / erasing repetition operation can be stably performed ¹⁰⁵ times or more, and the durability can be remarkably improved.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing a configuration of an optical medium according to one embodiment of the present invention.

FIG. 2 is a layout diagram showing a measurement system for recording / erasing characteristics in a stationary state.

FIG. 3 is a diagram showing the relationship between the content of a recording film material contained in a protective film and the number of recording / erasing repetitions, where the base material of the protective film is SiO ₂ .

FIG. 4 is a diagram showing the relationship between the content of the recording film material (Sb) contained in the protective film and the number of recording / erasing repetitions, where the base material of the protective film is SiO ₂ .

FIG. 5 is a diagram showing the relationship between the content of the recording film material contained in the protective film and the number of recording / erasing repetitions, where the base material of the protective film is Al ₂ O ₃ .

FIG. 6 is a diagram showing the relationship between the content of the recording film material contained in the protective film and the number of recording / erasing repetitions, where the base material of the protective film is Ta ₂ O ₅ .

[Explanation of symbols]

 11 Transparent substrate 12 Protective film 13 Recording film 14 Protective film 15 Metal film 21 Optical head 22 Laser light 23 Pulse generator

 ────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-4-71895 (JP, A)

Claims (10)

(57) [Claims] 1. A rewritable optical information recording medium in which light irradiation causes a reversible phase transition between an amorphous state and a crystalline state of a recording film, thereby enabling recording and erasing of information. constituent elements Ge film, Te, Sb, a 5 element Bi and Se, a protective film adjacent to the recording layer contains at least one element that make up the recording layer to the base material A rewritable optical information recording medium characterized by the above-mentioned. 2. A rewritable optical information recording medium in which light irradiation causes a reversible phase transition between an amorphous state and a crystalline state of a recording film, thereby enabling recording and erasing of information. 2. The rewritable light according to claim 1, wherein the constituent elements of the film are five elements of Ge, Te, Sb, Bi and Se, and the base material of the protective film adjacent to the recording film is made of an oxide. Information recording medium. 3. A rewritable optical information recording medium that causes a reversible phase transition between an amorphous state and a crystalline state of a recording film by light irradiation, thereby enabling information recording and erasing. elements that make up the film Ge, Te, Sb, B
i and Se, and the base material of the protective film is Si
At least one of O, SiO ₂ , Al ₂ O ₃ , and Ta ₂ O ₅
3. The rewritable optical information recording medium according to claim 1, wherein the optical information recording medium is of a kind. 4. that make up the recording film element Ge, Te, S
b, Bi and Se, and the base material of the protective film is made of at least one of SiO, SiO ₂ , Al ₂ O ₃ and Ta ₂ O ₅ , and at least one of the five elements of the recording film material The rewritable optical information recording according to any one of claims 1, 2, and 3, wherein when the base material is contained in the base material of the protective film, the content is in the range of 4 to 22 mol%. Medium. 5. that make up the recording film element Ge, Te, S
b, Bi and Se, and the base material of the protective film is at least one of SiO, SiO ₂ , Al ₂ O ₃ and Ta ₂ O ₅ , and one of the five elements of the recording film material is When contained in the base material of the protective film, the content is 4-1.
5. The rewritable optical information recording medium according to claim 1, wherein the content is in a range of 5 mol%. 6. element that make up the recording film Ge, Te, S
b, Bi, and Se, and the base material of the protective film is at least one of SiO, SiO ₂ , Al ₂ O ₃ , and Ta ₂ O ₅ , and the five elements of the recording film material are the protective film. When contained in the base material, the content is 13-22 mo
6. The rewritable optical information recording medium according to claim 1, wherein the rewritable optical information recording medium is in a range of 1%. 7. A rewritable optical information recording medium which causes a reversible phase transition between an amorphous state and a crystalline state of a recording film by light irradiation, thereby enabling recording and erasing of information. that make up the film element is Ge, Te and Sb
And the base material of the protective film is SiO, SiO ₂ ,
_{Al 2 O 3, Ta 2 O} 5 of the rewritable optical information recording medium characterized in that it consists of at least one. 8. elements that make up the recording layer is Ge, a 3 element Te and Sb, yet the base material of the protective film is Si
At least one of O, SiO ₂ , Al ₂ O ₃ , and Ta ₂ O ₅
Ge, Te, Sb, B in the base material of the protective film
When at least one of the five elements i and Se is included,
The rewritable optical information medium according to claim 7, wherein the content is in a range of 4 to 22 mol%. 9. elements that make up the recording layer is Ge, a 3 element Te and Sb, yet the base material of the protective film is Si
At least one of O, SiO ₂ , Al ₂ O ₃ , and Ta ₂ O ₅
Ge, Te, Sb, B in the base material of the protective film
9. The rewritable optical information recording medium according to claim 7, wherein when one of the five elements i and Se is contained, the content is in the range of 4 to 15 mol%. 10. elements that make up the recording layer is Ge, a 3 element Te and Sb, yet the base material of the protective film is Si
At least one of O, SiO ₂ , Al ₂ O ₃ , and Ta ₂ O ₅
Ge, Te, Sb, B in the base material of the protective film
When the five elements i and Se are included, the content is 13 to
9. The rewritable optical information recording medium according to claim 7, wherein the content is in the range of 22 mol%.