JP2004234817A - Information recording medium and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording medium with which high reliability and appropriate repeated rewriting performance are secured, without having to arrange an interface layer between a recording layer and a dielectric layer. <P>SOLUTION: On the surface of a substrate 1, a recording layer 4 and dielectric layers 2 and 6 are formed, and phase transformation is caused between a crystal phase and an amorphous phase by irradiating a light beam or applying electrical energy on the recording layer 4. The dielectric layers 2 and 6 are an Hf/Zr-Cr-O material layer, comprising a material which is expressed by a formula, for example, (MO<SB>2</SB>)<SB>N</SB>(Cr<SB>2</SB>O<SB>3</SB>)<SB>100-N</SB>(mol%)(in the formula, M is Hf only or is both Hf and Zr, and 20≤N≤80). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an information recording medium for optically or electrically recording, erasing, rewriting, and / or reproducing information, and a method for manufacturing the same.

  The inventor has developed a 4.7 GB / DVD-RAM which is a large-capacity rewritable phase change information recording medium that can be used as a data file and an image file. It has already been commercialized.

  This 4.7 GB / DVD-RAM is disclosed, for example, in Japanese Patent Laid-Open Publication No. 2001-322357 (Patent Document 1). FIG. 10 shows the configuration of a DVD-RAM disclosed in this publication. The information recording medium 31 shown in FIG. 10 includes a first dielectric layer 102, a first interface layer 103, a recording layer 4, a second interface layer 105, and a second dielectric layer on one surface of the substrate 1. 106, a light absorption correction layer 7, and a reflection layer 8 have a seven-layer structure formed in this order. In this information recording medium, the first dielectric layer is located closer to the incident laser light than the second dielectric layer. The first interface layer and the second interface layer have the same relationship. As described above, in the present specification, when the information recording medium includes two or more layers having the same function, the “first”, “second”, and Called "third."

The first dielectric layer 102 and the second dielectric layer 106 increase the light absorption efficiency of the recording layer 4 by adjusting the optical distance and reduce the difference between the reflectance of the crystalline phase and the reflectance of the amorphous phase. It has the function of increasing the signal amplitude by increasing it. Conventionally, ZnS-20 mol% SiO ₂ used as a material for a dielectric layer is an amorphous material, has low thermal conductivity, is transparent, and has a high refractive index. Further, ZnS-20 mol% SiO ₂ has a high film formation rate during film formation, and has good mechanical properties and moisture resistance. As described above, ZnS-20 mol% SiO ₂ is an excellent material suitable for forming a dielectric layer.

  When the thermal conductivity of the first dielectric layer 102 and the second dielectric layer 106 is low, when laser light is incident on the recording layer 4, heat is transferred from the recording layer 4 to the reflective layer 8 in a thickness direction. In this case, heat can be quickly diffused in the direction, and heat is less likely to diffuse in the in-plane direction of the dielectric layer 102 or 106. That is, the recording layer 4 is cooled by the dielectric layer in a shorter time, and an amorphous mark (recording mark) is easily formed. When it is difficult to form a recording mark, it is necessary to perform recording at a high peak power. When a recording mark is easily formed, recording can be performed at a low peak power. When the thermal conductivity of the dielectric layer is low, recording can be performed with a low peak power, and the recording sensitivity of the information recording medium increases. On the other hand, when the thermal conductivity of the dielectric layer is high, recording is performed at a high peak power, so that the recording sensitivity of the information recording medium decreases. The dielectric layer in the information recording medium exists in the form of a thin film so that the thermal conductivity cannot be measured accurately. Therefore, the inventors employ the recording sensitivity of the information recording medium as a relative criterion for knowing the magnitude of the thermal conductivity of the dielectric layer.

  The recording layer 4 is formed using a material that crystallizes at high speed, including Ge-Sn-Sb-Te. The information recording medium having such a material as the recording layer 4 has not only excellent initial recording performance but also excellent recording storability and rewrite storability. The phase change information recording medium records, erases, and rewrites information by utilizing the fact that the recording layer 4 undergoes reversible phase transformation between a crystalline phase and an amorphous phase. When the recording layer 4 is rapidly cooled by irradiating the recording layer 4 with high-power laser light (peak power), the irradiated portion becomes an amorphous phase and a recording mark is formed. When the recording layer is heated and gradually cooled by irradiating a low-power laser beam (bias power), the irradiated portion becomes a crystalline phase and the recorded information is erased. By irradiating the recording layer with laser light whose power has been modulated between the peak power level and the bias power level, it is possible to rewrite the already recorded information with new information while erasing it. The repetitive rewriting performance is represented by the maximum number of times that rewriting can be repeated within a range where the jitter value has no practical problem. It can be said that the larger the number of times, the better the repetitive rewriting performance. In particular, it is desired that an information recording medium for a data file has excellent repetitive rewriting performance.

The first interface layer 103 and the second interface layer 105 prevent mass transfer occurring between the first dielectric layer 102 and the recording layer 4 and between the second dielectric layer 106 and the recording layer 4. Has a function to prevent. Here, the mass transfer means that S contained in the first and second dielectric layers ZnS-20 mol% SiO ₂ diffuses into the recording layer during repeated rewriting by irradiating the recording layer with a laser beam. A phenomenon. When a large amount of S diffuses into the recording layer, the reflectance of the recording layer is reduced, and the rewriting performance is repeatedly deteriorated. This phenomenon is already known (see Non-Patent Document 1, N. Yamada et al. Japanese Journal of Applied Physics Vol. 37 (1998) pp. 2104-2110). In Japanese Patent Publication No. 10-275360 (Patent Document 2) and International Publication WO97 / 34298 (Patent Document 3), an interface layer for preventing this phenomenon is made of a nitride containing Ge. Is disclosed.

  The light absorption correction layer 107 adjusts the ratio Ac / Aa of the light absorption ratio Ac when the recording layer 4 is in a crystalline state and the light absorption ratio Aa when the recording layer 4 is in an amorphous state, so that the mark shape is not distorted during rewriting. There is a work to do. The reflection layer 8 has a function of optically increasing the amount of light absorbed by the recording layer 4, and thermally diffuses the heat generated in the recording layer 4 quickly to rapidly cool the recording layer 4. It has the function of facilitating crystallization. The reflection layer 8 also has a function of protecting the multilayer film from a use environment.

  As described above, the information recording medium shown in FIG. 10 has a structure in which seven layers each functioning as described above are stacked, thereby achieving excellent repetitive rewriting performance and high reliability in a large capacity of 4.7 GB. , Which has led to commercialization.

  The information recording medium described with reference to FIG. 10 is an example of a rewritable medium. As other information recording media, for example, a signal pit corresponding to information is formed on a substrate, and a read-only medium that reproduces information by irradiating a laser beam, and an irreversible phase transformation is performed by irradiating light. There is a write-once type medium that has a recording layer made of a material that is generated or decomposed, and in which information can be written only once.

Further, various materials have been proposed as materials suitable for the dielectric layer of the information recording medium. For example, Japanese Patent Laid-Open Publication No. 5-109115 (Patent Document 4) discloses that, in an optical information recording medium, a heat-resistant protective layer is formed of a mixture of a high melting point element having a melting point of 1600 K or more and a low alkali glass. Is disclosed. The publication discloses Nb, Mo, Ta, Ti, Cr, Zr, and Si as high melting point elements. The publication also discloses that the low-alkali glass contains SiO ₂ , BaO, B ₂ O ₃ or Al ₂ O ₃ as a main component.

Japanese Patent Laid-Open Publication No. 5-159373 (Patent Document 5) discloses that, in an optical information recording medium, a heat-resistant protective layer has at least one of nitride, carbide, oxide, and sulfide having a melting point higher than that of Si. And a low alkali glass. This publication exemplifies Nb, Zr, Mo, Ta, Ti, Cr, Si, Zn, and Al carbides, oxides, and sulfides as compounds having a high melting point. The publication also discloses that the low-alkali glass contains SiO ₂ , BaO, B ₂ O ₃ , and Al ₂ O ₃ as main components.

  Japanese Patent Laid-Open Publication No. 8-77604 (Patent Document 6) discloses that in a read-only information recording medium, a dielectric layer is made of Ce, La, Si, In, Al, Ge, Pb, Sn, Bi, Te, Oxides of at least one element selected from the group consisting of Ta, Sc, Y, Ti, Zr, V, Nb, Cr, and W, and Cd, Zn, Ga, In, Sb, Ge, Sn, Pb, and Bi It is disclosed that the material comprises a sulfide or selenide of at least one element selected from the group consisting of:

  Japanese Patent Laid-Open Publication No. 2001-67722 (Patent Document 7) discloses that in an optical recording medium, a first interface control layer and a second interface control layer are formed of Al, Si, Ti, Co, Ni, Ga, Ge. , Sb, Te, In, Au, Ag, Zr, Bi, Pt, Pd, Cd, P, Ca, Sr, Cr, Y, Se, La, a nitride containing at least one element group consisting of Li, It is disclosed that it is selected from oxides, carbides, and sulfides.

JP 2001-322357 A JP-A-10-275360 (Claims) WO97 / 34298 (Claims) JP-A-5-109115 (Claims) JP-A-5-159373 (Claims) JP-A-8-77604 (Claims) JP 2001-67722 A (Claims) N. Yamada et al. Japanese Journal of Applied Physics Vol.37 (1998) pp. 2104-2110

As described above, when the first and second dielectric layers are formed using ZnS-20 mol% SiO ₂ , an interface layer is required between the dielectric layer and the recording layer in order to prevent the diffusion of S. Is required. However, considering the price of the medium, it is desirable that the number of layers constituting the medium is as small as one. When the number of layers is small, it is possible to reduce the material cost, to reduce the size of the manufacturing apparatus, and to increase the production amount by shortening the manufacturing time, which leads to a reduction in the price of the medium.

The inventor has studied a possibility of eliminating at least one of the first interface layer and the second interface layer as one method of reducing the number of layers. In this case, the inventor considered that the dielectric layer needs to be formed of a material other than ZnS-20 mol% SiO ₂ so that the diffusion of S from the dielectric layer to the recording layer due to repeated recording does not occur. Further, as for the material of the dielectric layer, it should have good adhesion to the recording layer, which is a chalcogenide material, obtain high recording sensitivity equal to or higher than that of the seven-layer structure, be transparent, and It is desirable to have a high melting point so that it does not melt during recording.

  The present invention relates to an information recording medium in which a dielectric layer is formed so as to be in direct contact with a recording layer without providing an interface layer, wherein a substance does not move from the dielectric layer to the recording layer, and the dielectric layer and the recording layer The main object of the present invention is to provide an information recording medium which has good adhesion to the recording medium and has excellent repetitive rewriting performance.

  Note that none of the above Patent Documents 4 to 7 mentions the problem that a substance moves from the dielectric layer to the recording layer. Therefore, it should be noted that these publications do not teach the problem to be solved by the present invention and the means for solving the problem, that is, the specific composition.

The inventors formed a dielectric layer using various compounds as described in the examples below, and evaluated the adhesiveness of the dielectric layer to the recording layer and the rewriting performance of the information recording medium. evaluated. As a result, in a configuration in which the dielectric layers are directly provided above and below the recording layer without the interposition of an interface layer, when the dielectric layer is formed of a dielectric layer that easily diffuses into the recording layer, for example, the conventional ZnS-20 mol% SiO ₂ It was found that the adhesion to the recording layer was good, but the rewriting performance of the medium was poor. Further, for example, HfO ₂ and ZrO ₂ have a low thermal conductivity and a high melting point. Therefore, if they are used as a dielectric layer, the recording sensitivity of an information recording medium can be increased, and excellent rewriting performance can be improved. Can be secured. However, when the dielectric layer was formed using only HfO ₂ or only ZrO _2, the result that the adhesion to the recording layer was poor was obtained. Adhesion of the dielectric layer to the recording layer and repetitive rewriting performance for information recording media formed by using a dielectric layer in contact with the recording layer using various other oxides, nitrides, sulfides, and selenides Was evaluated. However, when the dielectric layer was formed using one kind of oxide, nitride, sulfide, or selenide, it was not possible to achieve both good adhesion and good repetitive rewriting performance.

Therefore, the inventor first studied formation of a dielectric layer by combining two or more compounds containing no S. As a result, they found that a combination of HfO ₂ and Cr ₂ O _{3 and} a combination of HfO ₂ , ZrO ₂ and Cr ₂ O ₃ were suitable as constituent materials of the dielectric layer in contact with the recording layer. It has been found that it is not necessary to form an interface layer when the amount (in the case of including Hf and Zr, the sum of the contents of Hf and Zr) and the content of Cr are within a specific range. Reached.

  That is, the present invention relates to an information recording medium for recording and / or reproducing information by irradiating light or applying electric energy, wherein the first metal component contains Hf, or Hf and Zr, A Hf / Zr-Cr-O-based material layer containing Cr as a component and further containing O, wherein the content of the first metal component in the Hf / Zr-Cr-O-based material layer is 30 atom% or less; In addition, the present invention provides an information recording medium in which the content of the second metal component is 7 atomic% or more and 37 atomic% or less.

  The information recording medium of the present invention is a medium for recording and / or reproducing information by irradiating light or applying electric energy. According to the present invention, a predetermined pit is formed in advance on a medium for repeatedly recording information (a so-called rewritable medium), a substrate, or the like, and information (for example, audio and images) is exclusively reproduced based on the pit. The present invention is applied to various media such as a medium and a medium on which information can be recorded only once (a so-called write-once medium). Therefore, the term “recording and / or reproducing” is used herein to indicate a medium that can perform both recording and reproducing and a medium that can only reproduce. Generally, light irradiation is performed by irradiating a laser beam (that is, a laser beam), and application of electric energy is performed by applying a voltage to the recording layer. Hereinafter, the Hf / Zr-Cr-O-based material layer constituting the information recording medium of the present invention will be described more specifically. In the following description, it is noted that the term “Hf / Zr—Cr—O-based material layer” refers to a layer in which the first metal component and the second metal component are contained in the above ratio. I want to.

  In the present invention, the first metal component is only Hf or Hf and Zr. The reason why the combination of Hf and Zr is specified as the first metal component is that Zr has similar physical and chemical properties to Hf. Therefore, a layer containing both Hf and Zr as the first metal component can be regarded as a layer in which a part of Hf is replaced with Zr in a layer containing only Hf as the first metal component. It should be noted that the designation “Hf / Zr” is used herein to generically refer to 1) a form containing only Hf and 2) a form containing both Hf and Zr. That is, "/" is used to simplify the expression. Also, when both Hf and Zr are included, it should be noted that the combined amount of the two elements needs to be within the above range as the content of the first metal component.

（式中、Ｍは第１金属成分を示し、ＱおよびＲはそれぞれ、０＜Ｑ≦３０、７≦Ｒ≦３７の範囲内にあり、且つ２０≦Ｑ＋Ｒ≦６０である）
で表される材料から実質的に成るＨｆ／Ｚｒ−Ｃｒ−Ｏ系材料層を、構成要素として含むものである。ここで、「原子％」とは、式（１）が、第１金属成分（即ち、Ｈｆ、あるいはＨｆとＺｒを含む場合にはＨｆとＺｒ）、第２金属成分（即ち、Ｃｒ）およびＯ原子を合わせた数を基準（１００％）として表された組成式であることを示している。以下の式においても「原子％」の表示は、同様の趣旨で使用されている。この材料がＨｆおよびＺｒの両方を含む場合、Ｑは両者の割合の合計に相当する。また、「実質的に成る」という用語は、上記式（１）に示される元素以外の成分がＨｆ／Ｚｒ−Ｃｒ−Ｏ系材料層に含まれるとしても、ごく僅かであり、当該他の成分が全体に占める割合（即ち、式（１）に示される成分と当該他の成分を合わせた数を基準としたときの当該他の成分の割合）が１０原子％以下であることを示すために用いている。以下において、「原子％」の表示を付した式で表される材料から「実質的に成る」というときには、同様のことを意味している。 More specifically, the information recording medium of the present invention has the formula (1):

(Wherein M represents the first metal component, Q and R are respectively in the range of 0 <Q ≦ 30, 7 ≦ R ≦ 37, and 20 ≦ Q + R ≦ 60)
And a Hf / Zr—Cr—O-based material layer substantially composed of the material represented by the following formula: Here, “atomic%” means that the formula (1) represents the first metal component (ie, Hf or Hf and Zr when Hf and Zr are included), the second metal component (ie, Cr) and O This indicates that the composition formula is expressed on the basis of the total number of atoms (100%). In the following formulas, the expression “atomic%” is used for the same purpose. If this material contains both Hf and Zr, Q corresponds to the sum of the proportions of both. Further, the term “consisting essentially of” means that even if a component other than the element represented by the above formula (1) is contained in the Hf / Zr—Cr—O-based material layer, it is very slight, In order to show that the ratio of the component to the whole (that is, the ratio of the other component based on the total number of the component represented by the formula (1) and the other component) is 10 atomic% or less. Used. In the following, the term “substantially composed” of a material represented by a formula with “atomic%” means the same.

  In the present specification, “M” indicates Hf when the Hf / Zr—Cr—O-based material layer includes only Hf, and indicates Hf when Hf and Zr are included. And both Zr and Zr. That is, the material represented by the above formula (1) includes a material containing only Hf as “M” and a material containing both Hf and Zr as “M”. The use of "M" is due to the fact that the physical and chemical properties of Hf and Zr are similar to each other and can be considered as one component, as described above. In this specification, a label such as “Hf—Cr—O-based material” may be used to indicate a material containing only Hf as the first metal component, and Hf and Zr may be used as the first metal component. In some cases, a label such as “Hf—Zr—Cr—O-based material” is used to indicate a material that contains the material.

In the formula (1), it does not matter what kind of compound the first metal component (M), the second metal component (Cr) and oxygen (O) exist. It is difficult to determine the composition of the compound when examining the composition of the layer formed in the thin film because the material is specified by such a formula. Actually, only the elemental composition (that is, the ratio of each atom) is determined. This is due to the fact that it is often requested. In the material represented by the formula (1), most of the first metal component exists as HfO ₂ or a mixture of HfO ₂ and ZrO ₂ together with O, and most of the second metal component exists as Cr ₂ O ₃ together with O. it seems to do.

The Hf / Zr—Cr—O-based material layer substantially consisting of the material represented by the above formula (1) is one of two dielectric layers adjacent to the recording layer in the information recording medium having the recording layer. Preferably, it exists as one of the dielectric layers, and more preferably, it exists as both of the dielectric layers. The dielectric layer containing the first metal component, the second metal component, and O in the above range has a high melting point and is transparent. Further, this layer ensures that MO ₂ (that is, HfO ₂ or a mixture of HfO ₂ and ZrO ₂ ) has excellent repetitive rewriting performance, and that Cr ₂ O ₃ has good adhesion to a recording layer made of a chalcogenide material. Secure. Therefore, this information recording medium does not peel off between the recording layer and the dielectric layer even without the interface layer, and exhibits excellent repetitive rewriting performance. Alternatively, the layer of the material represented by the formula (1) may be an interface layer located between the recording layer and the dielectric layer in the information recording medium.

（式中、Ｍは第１金属成分を示し、Ｎは２０≦Ｎ≦８０の範囲である）
で表される材料から実質的に成る層であってよい。式（１１）は、Ｈｆ／Ｚｒ−Ｃｒ−Ｏ系材料層がＭＯ₂とＣｒ₂Ｏ₃との混合物から成る場合に、２つの化合物の好ましい割合を表している。ここで、「ｍｏｌ％」とは、式（１１）が、各化合物の総数を基準（１００％）として表わされた組成式であることを示している。以下の式においても「ｍｏｌ％」の表示は、同様の趣旨で使用されている。この材料がＨｆＯ₂およびＺｒＯ₂の両方を含む場合、Ｎは両者の割合の合計に相当する。また、「実質的に成る」という用語は、上記式（１１）に示される化合物以外の成分がＨｆ／Ｚｒ−Ｃｒ−Ｏ系材料層に含まれるとしても、ごく僅かであり、当該他の成分が全体に占める割合（即ち、ＭＯ₂、Ｃｒ₂Ｏ₃および当該他の成分を合わせたモル数を基準としたときの当該他の成分の割合）が１０モル％以下であることを示すために用いている。以下において、「モル％」の表示を付した式で表される材料から「実質的に成る」というときは、同様のことを意味している。 In the information recording medium of the present invention, the Hf / Zr—Cr—O-based material layer has the formula (11):

(Wherein, M represents the first metal component, and N is in the range of 20 ≦ N ≦ 80)
May be a layer substantially consisting of the material represented by Formula (11) represents a preferable ratio of the two compounds when the Hf / Zr—Cr—O-based material layer is composed of a mixture of MO ₂ and Cr ₂ O ₃ . Here, “mol%” indicates that the formula (11) is a composition formula expressed with the total number of each compound as a reference (100%). In the following formulas, “mol%” is used for the same purpose. If this material contains both HfO ₂ and ZrO ₂ , N corresponds to the sum of the proportions of both. Further, the term “consisting essentially of” means that even if a component other than the compound represented by the above formula (11) is contained in the Hf / Zr—Cr—O-based material layer, it is very slight, Is 10% by mole or less in the total (i.e., the ratio of the other component based on the total number of moles of MO ₂ , Cr ₂ O ₃ and the other component). Used. In the following, the term “consists substantially” of the material represented by the formula with “mol%” means the same.

In this specification, MO ₂ indicates HfO ₂ when the Hf / Zr—Cr—O-based material layer contains only Hf, and Hf / Zr is contained in the Hf / Zr—Cr—O-based material layer. The case refers to HfO ₂ and ZrO ₂ . Are using the "MO _2", as described above, due to the fact that the physical and chemical properties of HfO ₂ and ZrO ₂ are similar to each other. Therefore, the material containing "MO _2" as the component, forms only HfO ₂ is contained as MO _2, and both of HfO ₂ and ZrO ₂ is included form contained as MO _2. Further, in the present specification, the expression “HfO ₂ / ZrO ₂ ” is used instead of “MO ₂ ”. Further, in this specification, to refer to a material containing only HfO ₂ as MO _2, may use the display as a HfO 2 _-Cr 2 _{O 3} based material. In addition, the term “HfO ₂ —ZrO ₂ —Cr ₂ O ₃ -based material” may be used to refer to a material containing both HfO ₂ and ZrO ₂ .

  The layer substantially composed of the material represented by the formula (11) may also exist as one of the two dielectric layers adjacent to the recording layer in the information recording medium having the recording layer. Preferably, it is more preferably present as both dielectric layers. The effect of using the layer substantially composed of the material represented by the formula (11) as the dielectric layer is as described in relation to the material represented by the formula (1).

（式中、Ｍは第１金属成分を示し、Ｕ、Ｖ、およびＴはそれぞれ、０＜Ｕ≦３０、７≦Ｖ≦３７、および０＜Ｔ≦１４の範囲内にあり、且つ２０≦Ｕ＋Ｖ＋Ｔ≦６０である）
で表される材料から実質的に成る層であってよい。 In the information recording medium of the present invention, the Hf / Zr—Cr—O-based material layer further includes Si, and has a formula (2):

(Wherein M represents the first metal component, U, V, and T are within the ranges of 0 <U ≦ 30, 7 ≦ V ≦ 37, and 0 <T ≦ 14, respectively, and 20 ≦ U + V + T ≦ 60)
May be a layer substantially consisting of the material represented by

Also in the formula (2), it does not matter what kind of compound each atom of the first metal component (M), the second metal component (Cr), silicon (Si) and oxygen (O) exists. The reason why the material is specified by such a formula is the same as that of the formula (1). In the material represented by the formula (2), it is considered that most of Si exists together with O as SiO ₂ .

  The layer substantially composed of the material represented by the formula (2) may also exist as one of the two dielectric layers adjacent to the recording layer in the information recording medium having the recording layer. Preferably, it is more preferably present as both dielectric layers. In an information recording medium using a Hf / Zr—Cr—O-based material layer containing Si as a dielectric layer, good adhesion between the dielectric layer and the recording layer is ensured, and excellent repetitive rewriting performance is ensured. In addition, higher recording sensitivity is realized. This is considered to be due to the fact that the thermal conductivity of the layer is reduced by including Si. Alternatively, the layer substantially composed of the material represented by the formula (2) may be an interface layer located between the recording layer and the dielectric layer in the information recording medium.

（式中、Ｍは第１金属成分を示し、ＸおよびＹはそれぞれ、２０≦Ｘ≦７０および２０≦Ｙ≦６０の範囲内にあり、且つ６０≦Ｘ＋Ｙ≦９０である）
で表される材料から実質的に成る層であってよい。式（２１）は、Ｓｉを含むＨｆ／Ｚｒ−Ｃｒ−Ｏ系材料層が、ＭＯ₂、Ｃｒ₂Ｏ₃、およびＳｉＯ₂の混合物から成る場合に、３つの化合物の好ましい割合を示している。式（２１）で表される材料から実質的に成る層も、記録層を有する情報記録媒体において記録層と隣接する誘電体層のうち、いずれか一方の誘電体層として存在することが好ましく、両方の誘電体層として存在することがより好ましい。あるいは、式（２１）で表される材料から実質的に成る層は、情報記録媒体において、記録層と誘電体層との間に位置する界面層としてもよい。 The Hf / Zr—Cr—O-based material layer containing Si is represented by the following formula (21):

(Wherein M represents the first metal component, X and Y are within the ranges of 20 ≦ X ≦ 70 and 20 ≦ Y ≦ 60, respectively, and 60 ≦ X + Y ≦ 90)
May be a layer substantially consisting of the material represented by Formula (21) shows a preferable ratio of the three compounds when the Hf / Zr—Cr—O-based material layer containing Si is composed of a mixture of MO ₂ , Cr ₂ O ₃ , and SiO ₂ . The layer substantially composed of the material represented by the formula (21) also preferably exists as one of the dielectric layers adjacent to the recording layer in the information recording medium having the recording layer, More preferably, it is present as both dielectric layers. Alternatively, the layer substantially composed of the material represented by the formula (21) may be an interface layer located between the recording layer and the dielectric layer in the information recording medium.

When a layer substantially made of the material represented by the formula (21) is used as the dielectric layer, SiO ₂ has a function of increasing the recording sensitivity of the information recording medium. In this case, in Expression (21), by setting 60 ≦ X + Y ≦ 90, good adhesion to the recording layer is ensured. The SiO ₂ ratio is adjusted by changing X + Y within this range, so that the recording sensitivity can be adjusted by appropriately selecting the SiO ₂ ratio. Further, in the formula (21), by setting 20 ≦ X ≦ 70 and 20 ≦ Y ≦ 60, MO ₂ and Cr ₂ O ₃ can be present in the layer at an appropriate ratio. Therefore, the dielectric layer substantially consisting of the material represented by the formula (21) is transparent and has excellent adhesion to the recording layer, and the information recording medium has good recording sensitivity and repetitive rewriting performance. Make sure you have.

（式中、Ｍは第１金属成分を示し、Ｚは、２５≦Ｚ≦６７の範囲内にある）
で表される。ＭＯ₂とＳｉＯ₂とを略等しい割合で含むと、構造が安定なＭＳｉＯ₄が形成される。ＭとしてＨｆのみが含まれ、ＨｆＯ₂とＳｉＯ₂とを略等しい割合で含む場合には、ＨｆＳｉＯ₄が形成される。ＭとしてＨｆおよびＺｒが含まれ、ＨｆＯ₂とＺｒＯ_２とを合わせた割合がＳｉＯ₂の割合と等しい場合には、ＨｆＳｉＯ₄とＺｒＳｉＯ_４が形成される。式（２２）で表される材料がＨｆＳｉＯ_４とＺｒＳｉＯ_４の両方を含む場合、ＺはＨｆＳｉＯ_４の含有量とＺｒＳｉＯ_４の含有量の和に相当する。式（２２）で表される材料から実質的に成る層も、記録層を有する情報記録媒体において記録層と隣接する誘電体層のうち、いずれか一方の誘電体層として存在することが好ましく、両方の誘電体層として存在することがより好ましい。式（２２）において、Ｚを２５≦Ｚ≦６７の範囲とすることにより、ＭＳｉＯ₄およびＣｒ₂Ｏ₃が適切な割合で層中に存在する。したがって、式（２２）で表される材料から実質的に成る誘電体層は、透明であって、且つ記録層との密着性に優れるとともに、情報記録媒体が、良好な記録感度および繰り返し書き換え性能を有することを確保する。あるいは、式（２２）で表される材料から実質的に成る層は、情報記録媒体において、記録層と誘電体層との間に位置する界面層としてもよい。 The material represented by the formula (21) may contain MO ₂ and SiO ₂ in substantially equal proportions. In this case, this material is represented by the following formula (22):

(Where M represents the first metal component, and Z is within the range of 25 ≦ Z ≦ 67)
Is represented by When MO ₂ and SiO ₂ are contained at substantially the same ratio, MSiO ₄ having a stable structure is formed. When only Hf is contained as M and HfO ₂ and SiO ₂ are contained in substantially equal proportions, HfSiO ₄ is formed. When M includes Hf and Zr, and the combined ratio of HfO ₂ and ZrO ₂ is equal to the ratio of SiO ₂ , HfSiO ₄ and ZrSiO ₄ are formed. When the material represented by the formula (22) includes both HfSiO ₄ and ZrSiO ₄ , Z corresponds to the sum of the HfSiO ₄ content and the ZrSiO ₄ content. The layer substantially composed of the material represented by the formula (22) also preferably exists as one of the dielectric layers adjacent to the recording layer in the information recording medium having the recording layer, More preferably, it is present as both dielectric layers. In the formula (22), when Z is in the range of 25 ≦ Z ≦ 67, MSiO ₄ and Cr ₂ O ₃ are present in the layer at an appropriate ratio. Therefore, the dielectric layer substantially consisting of the material represented by the formula (22) is transparent, has excellent adhesion to the recording layer, and has good recording sensitivity and repetitive rewriting performance. Ensure that you have Alternatively, the layer substantially composed of the material represented by the formula (22) may be an interface layer located between the recording layer and the dielectric layer in the information recording medium.

（式中、Ｍは第１金属成分であり、Ｄは、ＺｎＳ、ＺｎＳｅまたはＺｎＯであり、Ｃ、ＥおよびＦはそれぞれ、２０≦Ｃ≦６０、２０≦Ｅ≦６０、および１０≦Ｆ≦４０の範囲内にあり、且つ６０≦Ｃ＋Ｅ＋Ｆ≦９０である）
で表されるＨｆ／Ｚｒ−Ｃｒ−Ｚｎ−Ｏ系材料から実質的に成る層をさらに含んでいる情報記録媒体を提供する。以下の説明においては、式（３）で表される材料から実質的に成る層を、単に「Ｈｆ／Ｚｒ−Ｃｒ−Ｚｎ−Ｏ系材料層」と呼ぶ場合がある。 The present invention also relates to an information recording medium for recording and / or reproducing information by irradiating light or applying electric energy, wherein the first metal component contains Hf or Hf and Zr, and the second metal component contains Cr. Including and equation (3):

(Where M is the first metal component, D is ZnS, ZnSe or ZnO, and C, E and F are respectively 20 ≦ C ≦ 60, 20 ≦ E ≦ 60, and 10 ≦ F ≦ 40 And 60 ≦ C + E + F ≦ 90)
The present invention further provides an information recording medium further comprising a layer substantially composed of a Hf / Zr-Cr-Zn-O-based material represented by the formula: In the following description, a layer substantially composed of the material represented by the formula (3) may be simply referred to as “Hf / Zr—Cr—Zn—O-based material layer”.

The layer substantially composed of the material represented by the formula (3) also exists as one of the two dielectric layers adjacent to the recording layer in the information recording medium having the recording layer. Is preferable, and more preferably, it is present as both dielectric layers. The material represented by the formula (3) includes MO ₂ , Cr ₂ O _3, and SiO ₂ similarly to the material represented by the formula (21). Therefore, according to this material, a dielectric layer having excellent transparency and adhesion to the recording layer is formed, and the information recording medium including the dielectric layer has good recording sensitivity and repetitive rewriting performance. Have. Since the material represented by the formula (3) contains ZnS, ZnSe, or ZnO as the component D, the dielectric layer formed of this material has improved adhesion to a recording layer made of a chalcogenide material. Becomes Furthermore, the recording sensitivity can be further improved by adding ZnS or ZnSe, which tends to be in a crystalline state, to a MO ₂ —Cr ₂ O ₃ —SiO ₂ -based material, which tends to be in an amorphous state in a thin film state. . Alternatively, the layer substantially composed of the material represented by the formula (3) may be an interface layer located between the recording layer and the dielectric layer in the information recording medium.

In the formula (3), by setting 20 ≦ C ≦ 60 and 20 ≦ E ≦ 60, MO ₂ and Cr ₂ O ₃ can be present in the layer at an appropriate ratio. In the formula (3), by setting 10 ≦ F ≦ 40, the effect of the component D (for example, improvement in adhesion) can be achieved without impairing the rewriting performance of the information recording medium. Further, in the formula (3), by changing C + E + F in the range of 60 to 90, the recording sensitivity can be adjusted by appropriately adjusting the ratio of SiO ₂ .

（式中、Ｍは第１金属成分を示し、Ｄは、ＺｎＳ、ＺｎＳｅまたはＺｎＯであり、ＡおよびＢはそれぞれ、２５≦Ａ≦５４、および２５≦Ｂ≦６３の範囲内にあり、且つ５０≦Ａ＋Ｂ≦８８である）
で表される。前述のようにＭＯ₂とＳｉＯ₂を略等しい割合で含むことにより、安定な構造のＭＳｉＯ₄が形成される。この材料が、ＨｆＳｉＯ₄とＺｒＳｉＯ₄の両方を含む場合、Ａは、ＨｆＳｉＯ₄とＺｒＳｉＯ₄の含有率の総和になる。式（３１）で表される材料から実質的に成る層も、記録層を有する情報記録媒体において記録層と隣接する誘電体層のうち、いずれか一方の誘電体層として存在することが好ましく、両方の誘電体層として存在することがより好ましい。式（３１）において、ＡおよびＢをそれぞれ、２５≦Ａ≦５４、および２５≦Ｂ≦６３とすることにより、ＭＳｉＯ₄およびＣｒ₂Ｏ₃が適切な割合で層中に存在する。したがって、式（３１）で表される材料から実質的に成る誘電体層は、透明であって、且つ記録層との密着性に優れるとともに、情報記録媒体が良好な記録感度および繰り返し書き換え性能を有することを確保する。また、式（３１）で表される材料が誘電体層に含まれる場合には、ＳｉＯ₂および成分Ｄが、情報記録媒体の記録感度を高くし、成分Ｄが誘電体層の記録層への密着性をより向上させる。あるいは、式（３１）で表される材料から実質的に成る層は、情報記録媒体において、記録層と誘電体層との間に位置する界面層としてもよい。 The material represented by the formula (3) may contain MO ₂ and SiO ₂ in substantially equal proportions. In this case, this material is represented by the following formula (31):

(Wherein M represents the first metal component, D is ZnS, ZnSe or ZnO, A and B are within the ranges of 25 ≦ A ≦ 54 and 25 ≦ B ≦ 63, respectively, and 50 ≤A + B≤88)
Is represented by As described above, by containing MO ₂ and SiO ₂ at substantially the same ratio, MSiO ₄ having a stable structure is formed. When this material contains both HfSiO ₄ and ZrSiO ₄ , A is the sum of the contents of HfSiO ₄ and ZrSiO ₄ . The layer substantially composed of the material represented by the formula (31) also preferably exists as one of the dielectric layers adjacent to the recording layer in the information recording medium having the recording layer, More preferably, it is present as both dielectric layers. In the formula (31), by setting A and B to 25 ≦ A ≦ 54 and 25 ≦ B ≦ 63, respectively, MSiO ₄ and Cr ₂ O ₃ are present in an appropriate ratio in the layer. Therefore, the dielectric layer substantially consisting of the material represented by the formula (31) is transparent and has excellent adhesion to the recording layer, and the information recording medium has good recording sensitivity and repetitive rewriting performance. Make sure you have. When the material represented by the formula (31) is contained in the dielectric layer, SiO ₂ and the component D increase the recording sensitivity of the information recording medium, and the component D is applied to the recording layer of the dielectric layer. Improve adhesion. Alternatively, the layer substantially composed of the material represented by the formula (31) may be an interface layer located between the recording layer and the dielectric layer in the information recording medium.

  The information recording medium of the present invention preferably has a recording layer. In particular, the information recording medium of the present invention is preferably provided as a rewritable information recording medium.

  In the rewritable information recording medium, the recording layer is preferably one in which a phase transformation is reversibly generated by irradiation of light or application of electric energy. The recording layer in which the phase transformation occurs reversibly is specifically Ge-Sb-Te, Ge-Sn-Sb-Te, Ge-Bi-Te, Ge-Sn-Bi-Te, Ge-Sb-Bi-. It is preferable to include any one material selected from Te, Ge-Sn-Sb-Bi-Te, Ag-In-Sb-Te, and Sb-Te. These are all high-speed crystallization materials. Therefore, when a recording layer is formed from these materials, information can be recorded at a high density and a high transfer speed, and an information recording medium excellent in reliability (specifically, recording preservability or rewrite preservability) can be obtained. .

  The information recording medium of the present invention may have two or more recording layers. Such an information recording medium has, for example, a single-sided two-layer structure in which two recording layers are laminated on one surface side of a substrate via a dielectric layer and an intermediate layer. An information recording medium having a single-sided, two-layer structure records light on two recording layers by irradiating light from one side. According to this structure, it is possible to increase the recording capacity. Alternatively, the information recording medium of the present invention may have a recording layer formed on both surfaces of the substrate. All of the recording layers may be recording layers where the phase transformation occurs reversibly, or one or more of the recording layers may undergo a reversible phase transformation and the other recording layer may undergo a irreversible phase transformation. It may be one that occurs naturally.

  In the information recording medium of the present invention, when the recording layer undergoes reversible phase transformation, the thickness of the recording layer is desirably 15 nm or less. If it exceeds 15 nm, the heat applied to the recording layer diffuses in the plane, making it difficult to diffuse in the thickness direction, which may hinder information rewriting.

  The information recording medium of the present invention may have a configuration in which a first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer are formed in this order on one surface of a substrate. The information recording medium having this configuration is a medium that is recorded by light irradiation. In this specification, the “first dielectric layer” refers to a dielectric layer located closer to incident light, and the “second dielectric layer” refers to The dielectric layer located farther from the dielectric layer. That is, the irradiated light reaches the second dielectric layer from the first dielectric layer via the recording layer. The information recording medium having this configuration is used, for example, when recording and reproducing with a laser beam having a wavelength of about 660 nm.

  When the information recording medium of the present invention has this configuration, at least one of the first dielectric layer and the second dielectric layer is formed of the Hf / Zr—Cr—O-based material layer (specifically, A layer substantially composed of any one of the materials represented by the above formulas (1), (11), (2), (21) and (22)), or the above Hf / Zr-Cr- This is a Zn—O-based material layer (specifically, a layer substantially composed of the material represented by the formula (3) or (31)). Preferably, both dielectric layers are the Hf / Zr-Cr-O-based material layer or the Hf / Zr-Cr-Zn-O-based material layer. In that case, both dielectric layers may be layers having the same composition or layers having different compositions.

  As one mode of an information recording medium having this configuration, a first dielectric layer, an interface layer, a recording layer, a second dielectric layer, a light absorption correction layer, and a reflective layer are provided in this order on one surface of a substrate. The second dielectric layer is the Hf / Zr-Cr-O-based material layer or the Hf / Zr-Cr-Zn-O-based material layer, wherein the second dielectric layer is in contact with the recording layer. Recording media.

  The information recording medium of the present invention may have a configuration in which a reflective layer, a second dielectric layer, a recording layer, and a first dielectric layer are formed in this order on one surface of a substrate. This configuration is adopted when it is necessary to reduce the thickness of the substrate on which light enters. Specifically, when recording / reproducing with a laser beam having a short wavelength near 405 nm, the numerical aperture NA of the objective lens is increased to, for example, 0.85, and the focal position is made shallow. Medium is used. In order to use such a wavelength and a numerical aperture NA, the thickness of a substrate on which light is incident needs to be, for example, about 60 to 120 μm. It is difficult to form a layer on the surface of such a thin substrate. Therefore, the information recording medium having this configuration is specified as being formed by sequentially forming a reflective layer or the like on one surface of a substrate on which light does not enter, as a support.

  When the information recording medium of the present invention has this configuration, at least one of the first dielectric layer and the second dielectric layer is formed of the Hf / Zr—Cr—O-based material layer or the Hf. / Zr—Cr—Zn—O-based material layer. Preferably, both dielectric layers are the Hf / Zr-Cr-O-based material layer or the Hf / Zr-Cr-Zn-O-based material layer. In that case, both dielectric layers may be layers having the same composition or layers having different compositions.

  As one mode of an information recording medium having this configuration, a reflection layer, a light absorption correction layer, a second dielectric layer, a recording layer, an interface layer, and a first dielectric layer are provided in this order on one surface of a substrate. The second dielectric layer is an Hf / Zr-Cr-O-based material layer or the Hf / Zr-Cr-Zn-O-based material layer, and is in contact with the recording layer. Information recording media;

  The present invention also provides, as a method for manufacturing the information recording medium of the present invention, a manufacturing method including a step of forming the above-described Hf / Zr-Cr-O-based material layer by a sputtering method. According to the sputtering method, an Hf / Zr—Cr—O-based material layer having a composition substantially the same as the composition of the sputtering target can be formed. Therefore, according to this manufacturing method, an Hf / Zr—Cr—O-based material layer having a desired composition can be easily formed by appropriately selecting a sputtering target.

（式中、Ｍは第１金属成分を示し、ＪおよびＫはそれぞれ、３≦Ｊ≦２４、および１１≦Ｋ≦３６であり、且つ３４≦Ｊ＋Ｋ≦４０である）
で表される材料から実質的に成るものを使用できる。式（１０）は、後述する式（１１０）で表される材料を元素組成で表した式に相当する。したがって、このターゲットによれば、上記式（１０）で表される材料から実質的に成る層を形成することができる。 Specifically, the following formula (10) is used as a sputtering target:

(Wherein, M represents the first metal component, J and K are respectively 3 ≦ J ≦ 24, 11 ≦ K ≦ 36, and 34 ≦ J + K ≦ 40)
Can be substantially composed of the material represented by The formula (10) corresponds to a formula in which a material represented by a formula (110) described later is represented by an elemental composition. Therefore, according to this target, a layer substantially composed of the material represented by the above formula (10) can be formed.

  An element composition of a layer formed by sputtering may be different from an element composition of a sputtering target depending on a sputtering apparatus, sputtering conditions, dimensions of a sputtering target, and the like. Even if such a difference occurs when a sputtering target made of the material represented by the above formula (10) is used, the element composition of the formed layer is at least as large as that represented by the above formula (1). Become.

（式中、Ｍは第１金属成分を示し、ｎは２０≦ｎ≦８０である）
で表される材料から実質的に成るものを使用してよい。これは、スパッタリングターゲットの組成を、ＭＯ₂とＣｒ₂Ｏ₃の割合で表した式に相当する。このようにスパッタリングターゲットを特定しているのは、通常、第１金属成分としてのＨｆまたはＨｆとＺｒ、第２金属成分としてのＣｒ、およびＯを含む材料から成るスパッタリングターゲットは、この第１金属成分の酸化物と第２金属成分の酸化物の組成が表示されて、提供されることによる。また、発明者は、組成がそのように表示されたスパッタリングターゲットをＸ線マイクロアナライザーで分析して得た元素組成が、表示されている組成から算出される元素組成と略等しくなることを（即ち、組成表示（公称組成）が適正であること）を確認している。したがって、このスパッタリングターゲットによれば、式（１１）で表される材料から実質的に成る層が形成される。 In the method for manufacturing an information recording medium of the present invention, the sputtering target is represented by the following formula (110):

(Wherein, M represents a first metal component, and n satisfies 20 ≦ n ≦ 80)
May consist essentially of the material represented by This corresponds to a formula in which the composition of the sputtering target is represented by the ratio of MO ₂ and Cr ₂ O ₃ . The reason why the sputtering target is specified as described above is that the sputtering target made of a material containing Hf or Hf and Zr as the first metal component, Cr and O as the second metal component is usually the first metal. The composition of the oxide of the component and the oxide of the second metal component is displayed and provided. Further, the inventor has confirmed that the element composition obtained by analyzing the sputtering target whose composition is indicated as such with an X-ray microanalyzer is substantially equal to the element composition calculated from the indicated composition (ie, , The composition display (nominal composition) is appropriate). Therefore, according to this sputtering target, a layer substantially composed of the material represented by the formula (11) is formed.

（式中、Ｍは第１金属成分を示し、Ｇ、ＨおよびＬは、４≦Ｇ≦２１、１１≦Ｈ≦３０、２≦Ｌ≦１２であり、且つ３４≦Ｇ＋Ｈ＋Ｌ≦４０である）
で表される材料から実質的に成るものを用いてよい。このスパッタリングターゲットを使用すれば、式（２１）または式（２）で表される材料から実質的に成る層が形成される。 In the method for manufacturing an information recording medium of the present invention, in order to form a Hf / Zr—Cr—O-based material layer containing Si, the following formula (20) is used as a sputtering target:

(Wherein, M represents a first metal component, G, H, and L are 4 ≦ G ≦ 21, 11 ≦ H ≦ 30, 2 ≦ L ≦ 12, and 34 ≦ G + H + L ≦ 40)
What consists substantially of the material represented by these may be used. By using this sputtering target, a layer substantially consisting of the material represented by the formula (21) or the formula (2) is formed.

（式中、Ｍは第１金属成分を示し、ｘおよびｙはそれぞれ、２０≦ｘ≦７０、および２０≦ｙ≦６０であり、且つ６０≦ｘ＋ｙ≦９０である）
で表される材料から実質的に成るものを使用してよい。このようにスパッタリングターゲットを特定しているのは、ＨｆまたはＨｆとＺｒの組合せである第１金属成分、Ｃｒである第２金属成分、ならびにＳｉおよびＯを含む材料から成るスパッタリングターゲットが、通常、ＭＯ₂（即ち、ＨｆＯ₂、またはＨｆとＺｒとを含む場合にはＨｆＯ₂とＺｒＯ₂）、ならびにＣｒ₂Ｏ₃およびＳｉＯ₂の組成が表示されて、提供されていることによる。発明者らは、式（２１０）のように組成が表示されているターゲットについても、組成表示（即ち、公称組成）が適正であることを確認している。したがって、このスパッタリングターゲットによれば、式（２１）で表される材料から実質的に成る層が形成される。 In the method for manufacturing an information recording medium of the present invention, the sputtering target is represented by the following formula (210):

(Where M represents the first metal component, x and y are respectively 20 ≦ x ≦ 70, 20 ≦ y ≦ 60, and 60 ≦ x + y ≦ 90)
May consist essentially of the material represented by The sputtering target is specified in this way because the first metal component which is Hf or a combination of Hf and Zr, the second metal component which is Cr, and the sputtering target made of a material containing Si and O are usually used. MO ₂ (ie, HfO ₂ , or HfO ₂ and ZrO ₂ if Hf and Zr are included), and the composition of Cr ₂ O ₃ and SiO ₂ , as indicated and provided. The inventors have confirmed that the composition display (that is, the nominal composition) is appropriate for the target whose composition is displayed as in the equation (210). Therefore, according to this sputtering target, a layer substantially consisting of the material represented by the formula (21) is formed.

（式中、Ｍは第１金属成分を示し、ｚは、２５≦ｚ≦６７である）
で表される材料から実質的に成るものである。このスパッタリングターゲットによれば、式（２２）で示される材料から実質的に成る層が形成される。 The sputtering target represented by the above formula (210) may contain MO ₂ and SiO ₂ in substantially equal proportions. In that case, the sputtering target has the formula (220):

(Wherein, M represents the first metal component, and z satisfies 25 ≦ z ≦ 67)
Substantially consisting of the material represented by According to this sputtering target, a layer substantially composed of the material represented by the formula (22) is formed.

（式中、Ｍは第１金属成分を示し、Ｄは、ＺｎＳ、ＺｎＳｅまたはＺｎＯであり、ｃ、ｅおよびｆはそれぞれ、２０≦ｃ≦６０、および２０≦ｅ≦６０、１０≦ｆ≦４０であり、且つ６０≦ｃ＋ｅ＋ｆ≦９０である）
で表される材料から実質的に成るものを使用してよい。このようにスパッタリングターゲットを特定しているのは、ＨｆまたはＨｆとＺｒの組み合わせである第１金属成分、Ｃｒである第２金属成分、ＳｉおよびＯに加えて、成分Ｄを含むターゲットが、ＭＯ₂（即ち、ＨｆＯ₂、またはＨｆとＺｒとを含む場合にはＨｆＯ₂とＺｒＯ₂）、Ｃｒ₂Ｏ₃、ＳｉＯ₂、および成分Ｄの組成が表示されて、供給されていることによる。このスパッタリングターゲットによれば、式（３）で示される材料から実質的に成る層が形成される。 The present invention also provides, as a method for manufacturing the information recording medium of the present invention, a manufacturing method including the step of forming the above-described Hf / Zr-Cr-Zn-O-based material layer by sputtering. According to the sputtering method, an Hf / Zr-Cr-Zn-O-based material layer having substantially the same composition as the sputtering target can be formed. Specifically, the following formula (30) is used as a sputtering target:

(Wherein, M represents the first metal component, D is ZnS, ZnSe or ZnO, c, e and f are respectively 20 ≦ c ≦ 60 and 20 ≦ e ≦ 60, 10 ≦ f ≦ 40 And 60 ≦ c + e + f ≦ 90)
May consist essentially of the material represented by In this manner, the sputtering target is specified because the target including the first metal component, which is Hf or a combination of Hf and Zr, the second metal component, which is Cr, Si and O, and the component D is MO. ₂ (that is, HfO ₂ , or HfO ₂ and ZrO ₂ when Hf and Zr are included), Cr ₂ O ₃ , SiO ₂ , and the composition of the component D are indicated and supplied. According to this sputtering target, a layer substantially composed of the material represented by the formula (3) is formed.

（式中、Ｍは第１金属成分を示し、Ｄは、ＺｎＳ、ＺｎＳｅまたはＺｎＯであり、ａおよびｂはそれぞれ、２５≦ａ≦５４、および２５≦ｂ≦６３の範囲内にあり、且つ５０≦ａ＋ｂ≦８８である）
で表される材料から実質的に成るものである。このスパッタリングターゲットによれば、式（３１）で示される材料から実質的に成る層が形成される。 The sputtering target represented by the above formula (30) may contain MO ₂ and SiO ₂ at a substantially equal ratio. In that case, the sputtering target has the formula (310):

(Wherein M represents the first metal component, D is ZnS, ZnSe or ZnO, a and b are within the ranges of 25 ≦ a ≦ 54 and 25 ≦ b ≦ 63, respectively, and 50 ≦ a + b ≦ 88)
Substantially consisting of the material represented by According to this sputtering target, a layer substantially composed of the material represented by the formula (31) is formed.

The present invention relates to an information recording medium having a recording layer, wherein a dielectric layer formed in direct contact with the recording layer is preferably made of a HfO ₂ —Cr ₂ O ₃ -based material, an HfO ₂ -Cr ₂ O ₃ -SiO ₂ -based material. Or a material in which ZnS, ZnSe, or ZnO is mixed with these materials, or a material in which a part of HfO ₂ of these materials is replaced with ZrO ₂ . According to this feature, the number of layers can be reduced by eliminating the interface layer between the recording layer and the dielectric layer, which was possessed by the conventional optical information recording medium, and high reliability and excellent repetitive rewriting can be achieved. An optical information recording medium having high performance and high recording sensitivity can be realized. In addition, when a layer of these materials is used as a dielectric layer for insulating the recording layer in an information recording medium to which electric energy is applied, a phase change of the recording layer can be generated with a small electric energy. it can.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are illustrative, and the present invention is not limited to the following embodiments.

(Embodiment 1)
As Embodiment 1 of the present invention, an example of an optical information recording medium for recording and reproducing information using laser light will be described. FIG. 1 shows a partial cross section of the optical information recording medium.

  In the information recording medium 25 shown in FIG. 1, a first dielectric layer 2, a recording layer 4, a second dielectric layer 6, a light absorption correction layer 7, and a reflection layer 8 are provided on one surface of the substrate 1. It has a configuration in which the dummy substrate 10 is formed in order, and the dummy substrate 10 is further bonded with the bonding layer 9. The information recording medium having this configuration can be used as a 4.7 GB / DVD-RAM that performs recording and reproduction with a laser beam in the red region near the wavelength of 660 nm. A laser beam 12 is incident on the information recording medium having this configuration from the substrate 1 side, thereby recording and reproducing information. The information recording medium 25 is different from the conventional information recording medium 31 shown in FIG. 10 in that it does not have the first interface layer 103 and the second interface layer 105.

  In the first embodiment, both first dielectric layer 2 and second dielectric layer 6 are Hf / Zr—Cr—O-based material layers or Hf / Zr—Cr—Zn—O-based material layers. is there.

In general, the material of the dielectric layer must be 1) transparent, 2) have a high melting point, and do not melt during recording, and 3) have good adhesion to the recording layer, which is a chalcogenide material. Required. Being transparent is a characteristic necessary for passing the laser beam 12 incident from the substrate 1 side to reach the recording layer 4. This property is particularly required for the first dielectric layer on the incident side. The high melting point is a characteristic necessary to ensure that the material of the dielectric layer does not mix into the recording layer when the laser beam at the peak power level is irradiated. When the material of the dielectric layer is mixed in the recording layer, the repetitive rewriting performance is significantly reduced. Good adhesion to the recording layer, which is a chalcogenide material, is a necessary property for ensuring the reliability of the information recording medium. Further, the material of the dielectric layer is such that the obtained information recording medium is a conventional information recording medium (that is, a medium in which an interface layer is located between a dielectric layer composed of ZnS-20 mol% SiO ₂ and a recording layer). It is necessary to select a recording sensitivity equal to or higher than that.

The Hf / Zr—Cr—O-based material layer is preferably a layer substantially composed of a mixture of HfO ₂ and Cr ₂ O ₃ or a mixture of HfO ₂ , ZrO ₂ and Cr ₂ O ₃ . HfO ₂ and ZrO ₂ are transparent, have high melting points, and have low thermal conductivity among oxides. In particular, since the melting point of HfO ₂ is as high as about 2800 ° C., the heat resistance of the information recording medium can be improved by using a material containing it as the dielectric layer. Although the melting point of ZrO ₂ is lower than that of HfO ₂ , it is as high as about 2700 ° C. ZrO ₂ is more cost effective than HfO ₂ . Therefore, by using ZrO ₂ instead of a part of HfO ₂ , it is possible to obtain an information recording medium at low cost while securing a high melting point of the Hf / Zr—Cr—O-based material layer with Hf. Become. Alternatively, by combining HfO ₂ and ZrO ₂ , the melting point of the Hf / Zr—Cr—O-based material layer can be adjusted. Cr ₂ O ₃ has good adhesion to the recording layer, which is a chalcogenide material. Therefore, the layers containing the mixture of the two or three kinds of oxides are referred to as first and second dielectric layers 2 and 6 and are formed so as to be in contact with the recording layer 4 as shown in FIG. It is possible to realize the information recording medium 25 having excellent rewriting performance and good adhesion between the recording layer and the dielectric layer. The mixture of MO ₂ (M is Hf or Hf and Zr) and Cr ₂ O ₃ is represented by the above formula (11), that is, (MO ₂ ) _N (Cr ₂ O ₃ ) _100-N (mol%). . In this mixture, the Cr ₂ O ₃ content (that is, 100-N) is preferably 20 mol% or more. If the content of Cr ₂ O ₃ is too large, the recording sensitivity of the information recording medium decreases, so the content of Cr ₂ O ₃ is preferably 80 mol% or less. More preferably, it is 30 mol% or more and 50 mol% or less.

The first and second dielectric layers 2 and 6 may be Hf / Zr-Cr-O-based material layers containing Si. The Hf / Zr—Cr—O-based material layer containing Si is preferably substantially composed of MO ₂ (M is Hf or Hf and Zr), a mixture of Cr ₂ O ₃ and SiO ₂ . This mixture is represented by the above formula (21), that is, (MO ₂ ) _X (Cr ₂ O ₃ ) _Y (SiO ₂ ) _100-XY . In this formula, X and Y are within the ranges of 20 ≦ X ≦ 70 and 20 ≦ Y ≦ 60, respectively, where 60 ≦ X + Y ≦ 90.

FIG. 7 shows a composition range of the material represented by the formula (21). In FIG. 7, the coordinates are (MO ₂ , Cr ₂ O ₃ , SiO ₂ ). In this figure, the materials represented by the formula (21) are a (70, 20, 10), b (40, 20, 40), c (20, 40, 40), d (20, 60, 20) , E (30, 60, 10) within the range (including on the line).

The Hf / Zr—Cr—O-based material layer containing SiO ₂ increases the recording sensitivity of the information recording medium. Further, by adjusting the ratio of SiO ₂ , it is possible to adjust the recording sensitivity. To increase the recording sensitivity by SiO _2, the content in the mixture of SiO ₂ is preferably at least 10 mol%. On the other hand, if the content of SiO ₂ is large, the adhesion to the recording layer 4 is deteriorated. Therefore, the content of SiO ₂ is preferably 40 mol% or less. The functions performed by HfO ₂ , ZrO _2, and Cr ₂ O ₃ are as described above, and when mixed at an appropriate ratio, the performance of the information recording medium is made appropriate. In the case of a MO ₂ —Cr ₂ O ₃ —SiO ₂ mixture, the content of Cr ₂ O ₃ is preferably 20 mol% or more and 60 mol% or less, and the content of MO ₂ is 20 mol% or more and 70 mol% or less. preferable. The first dielectric layer 2 and the second dielectric layer 6 may be layers made of a mixture having different contents of SiO ₂ . For example, the first dielectric layer 2 is (MO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₃₀ (SiO ₂ ) ₂₀ (mol%), and the second dielectric layer 6 is (MO ₂ ) ₄₀ (Cr ₂ O). ₃ ) It may be ₂₀ (SiO ₂ ) ₄₀ (mol%).

When the content of MO ₂ and SiO ₂ is substantially equal in the MO ₂ —Cr ₂ O ₃ —SiO ₂ mixture, it is preferable that MSiO ₄ is contained. The mixture in which MSiO ₄ is formed is represented by the above formula (22), that is, (MSiO ₄ ) _Z (Cr ₂ O ₃ ) _100-Z (mol%). In this equation, Z is in the range of 25 ≦ Z ≦ 67. When MO ₂ and SiO ₂ are contained in substantially equal proportions, MSiO ₄ is generated, and a more strongly bonded MO ₂ —SiO ₂ system is obtained. Z is more preferably in the range of 33 ≦ Z ≦ 50 in order to further improve the adhesiveness to the recording layer and secure the repetitive rewriting performance and high recording sensitivity of the information recording medium.

The Hf / Zr—Cr—Zn—O-based material layer is formed by mixing a mixture of HfO ₂ , Cr ₂ O ₃ , and SiO ₂ , or a mixture of HfO ₂ , ZrO ₂ , Cr ₂ O ₃ , and SiO ₂ with ZnS, The layer is substantially composed of a mixture further containing ZnSe or ZnO. This mixture is represented by the above formula (3), that is, (MO ₂ ) _C (Cr ₂ O ₃ ) _E (D) _F (SiO ₂ ) _100-CEF (mol%). In this formula, M is the first metal component (ie, Hf or a combination of Hf and Zr), and C, E, and F are respectively 20 ≦ C ≦ 60, 20 ≦ E ≦ 60, and 10 ≦ F ≦ 40. And 60 ≦ C + E + F ≦ 90. When the mixture contains the component D, the layer made of the mixture adheres better to the recording layer 4. Further, ZnS and ZnSe have strong crystallinity even in a thin film, and when added to an amorphous MO ₂ —Cr ₂ O ₃ —SiO ₂ mixture, the thermal conductivity of the mixture is further reduced. Therefore, when the first and second dielectric layers 2 and 6 are formed of a mixture containing ZnS or ZnSe, the recording sensitivity of the information recording medium can be further increased. By mixing the four types of materials in this manner, information having a recording sensitivity suitable for recording / erasing conditions (linear velocity of a medium and a wavelength of a laser beam), and having excellent adhesion and repetitive rewriting performance can be obtained. A recording medium can be realized.

The mixture represented by the above formula (3) may contain MO ₂ and SiO ₂ in substantially equal proportions. Such a mixture is represented by the above formula (31), that is, (MSiO ₄ ) _A (Cr ₂ O ₃ ) _B (D) _100-AB (mol%). In this formula, M is the first metal component (ie, Hf or a combination of Hf and Zr), and A and B are within the ranges of 25 ≦ A ≦ 54 and 25 ≦ B ≦ 63, respectively, and 50 ≦ A + B ≦ 88. By containing MO ₂ and SiO ₂ in substantially equal proportions, MSiO ₄ is formed, and an HfO ₂ —SiO ₂ system or HfO ₂ —ZrO ₂ —SiO ₂ system having stronger bonding is obtained. This makes it possible to realize an information recording medium having a recording sensitivity more suitable for recording and erasing conditions, and also having excellent adhesion and repeated rewriting performance.

When both Hf and Zr are included as the first metal component in the Hf / Zr-Cr-O-based material layer, the content of Hf and Zr is preferably 30 atomic% or less as described above. Therefore, the Hf—Zr—Cr—O-based material layer may contain, for example, 1 atomic% of Hf and 29 atomic% of Zr. Alternatively, the Hf—Zr—Cr—O-based material layer may contain 20 atomic% of Hf and 3 atomic% of Zr. When both Hf and Zr are included as the first metal component, the mixing ratio of Hf and Zr is not particularly limited, and may be appropriately determined in consideration of the heat resistance provided by HfO ₂ and the economics of ZrO _2. Selected. Specifically, the Hf—Zr—Cr—O-based material layer is made of a material represented by (HfO ₂ ) ₂₅ (ZrO ₂ ) ₁₀ (Cr ₂ O ₃ ) ₆₅ (mol%) or (HfO ₂ ) ₃ It may be a layer substantially made of a material represented by (ZrO ₂ ) ₆₀ (Cr ₂ O ₃ ) ₃₇ (mol%) or the like.

  In the information recording medium of the present invention, one of the first and second dielectric layers 2 and 6 is an Hf-Cr-O-based material layer, an Hf-Cr-Zn-O-based material layer, or an Hf-Zr-Cr. -O-based material layer, and the other may be a Hf-Zr-Cr-Zn-O-based material layer. Even if both the first and second dielectric layers 2 and 6 are Hf-Zr-Cr-Zn-O-based material layers, the object of the present invention can be achieved.

  As described above, the Hf / Zr-Cr-O-based material layer and the Hf / Zr-Cr-Zn-O-based material layer have the above formulas (1), (11), (2), (21), It contains 90 mol% or more of the material represented by (3) or (31). That is, when other components other than the components represented by the above formulas (hereinafter referred to as “third component”) are contained in less than 10 mol%, the thermal stability and moisture resistance of the material layer are not changed. However, it is preferably used as the first dielectric layer 2 and the second dielectric layer 6. The third component is unavoidably included or formed when the Hf / Zr-Cr-O-based material layer or the Hf / Zr-Cr-Zn-O-based material layer is formed. . As the third component, for example, a dielectric, a metal, a semimetal, a semiconductor, and / or a nonmetal are included in the Hf / Zr-Cr-O-based material layer or the Hf / Zr-Cr-Zn-O-based material layer.

More specifically, the dielectric contained as the third component may be Al ₂ O ₃ , CeO ₂ , CoO, CuO, Cu ₂ O, Dy ₂ O ₃ , Er ₂ O ₃ , FeO, Fe ₂ O ₃ , Fe _{2 3} O ₄ , Ga ₂ O ₃ , Ho ₂ O ₃ , In ₂ O ₃ , a mixture of In ₂ O ₃ and SnO ₂ , La ₂ O ₃ , MgO, MnO, Mn ₃ O ₄ , Mo ₂ O ₅ , Nb _{2 O 5, Nd 2 O 3,} NiO, Sc 2 O 3, Sm 2 O 3, SnO, SnO 2, Ta 2 O 5, Tb 4 O 7, TiO 2, WO 3, Y 2 O 3, Yb 2 O 3 , AlN, BN, CrN, Cr 2 N, HfN, NbN, Si 3 N 4, TaN, TiN, VN, ZrN, B 4 C, Cr 3 C 2, HfC, Mo 2 C, NbC, SiC, TaC, TiC _{, VC, W 2 C, WC} , and a ZrC.

  The metals contained as the third component are Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Mo, W, Mn, Fe, Ni, Pd, Pt, Cu, Ag, Au, Zn, La, Ce. , Nd, Sm, Gd, Tb, Dy and Yb.

  The semimetals and semiconductors contained as the third component are more specifically B, Al, C, Ge and Sn. Non-metals contained as the third component are more specifically Sb, Bi, Te and Se.

  The first dielectric layer 2 and the second dielectric layer 6 form a crystal by changing the optical path length (ie, the product nd of the refractive index n of the dielectric layer and the film thickness d of the dielectric layer). Absorbance Ac (%) of the phase recording layer 4, the light absorption Aa (%) of the amorphous phase recording layer 4, and the light reflectance Rc of the information recording medium 25 when the recording layer 4 is crystalline. (%), The light reflectance Ra (%) of the information recording medium 25 when the recording layer 4 is in the amorphous phase, and the information recording medium in the part where the recording layer 4 is in the crystalline phase and the part where the recording layer 4 is in the amorphous phase. It has a function of adjusting the phase difference Δφ of the 25 light beams. In order to increase the reproduction signal amplitude of the recording mark and improve the signal quality, it is desirable that the reflectance difference (| Rc-Ra |) or the reflectance ratio (Rc / Ra) is large. It is also desirable that Ac and Aa are large so that the recording layer 4 absorbs laser light. The optical path lengths of the first dielectric layer 2 and the second dielectric layer 6 are determined so as to satisfy these conditions simultaneously. The optical path length satisfying these conditions can be accurately determined by calculation based on, for example, a matrix method (see, for example, Hiroshi Kubota, “Wave Optics”, Iwanami Shinsho, 1971, Chapter 3).

  The Hf / Zr-Cr-O-based material and the Hf / Zr-Cr-Zn-O-based material described above have different refractive indexes depending on their compositions. Generally, these materials have a refractive index in the range of 1.8 to 2.5. When the refractive index of the dielectric layer is n, the film thickness is d (nm), and the wavelength of the laser beam 12 is λ (nm), the optical path length nd is represented by nd = aλ. Here, a is a positive number. In order to improve the signal quality by increasing the reproduction signal amplitude of the recording mark on the information recording medium 25, for example, it is preferable that 15% ≦ Rc and Ra ≦ 2%. In order to eliminate or reduce mark distortion due to rewriting, it is preferable that 1.1 ≦ Ac / Aa. The optical path lengths (aλ) of the first dielectric layer 2 and the second dielectric layer 6 were accurately obtained by a calculation based on the matrix method so that these preferable conditions were simultaneously satisfied. The thickness d of the dielectric layer was determined from the obtained optical path length (aλ) and λ and n. As a result, it was found that the thickness of the first dielectric layer 2 was preferably 100 nm to 200 nm, and more preferably 130 nm to 170 nm. Further, it was found that the thickness of the second dielectric layer 6 was preferably 20 nm to 70 nm, and more preferably 30 nm to 60 nm.

  The substrate 1 is usually a transparent disk-shaped plate. A guide groove for guiding laser light may be formed on the surface on which the dielectric layer, the recording layer, and the like are formed. When the guide groove is formed in the substrate, a groove portion and a land portion are formed when a cross section of the substrate is viewed. It can be said that the groove portion is located between two adjacent land portions. Therefore, the surface on which the guide groove is formed has a top surface and a bottom surface connected by the side wall. In the present specification, in the direction of the laser light 12, a surface closer to the laser light 12 is called a “groove surface” for convenience, and a surface farther from the laser light is called a “land surface” for convenience. Call. In FIG. 1, the bottom surface 23 of the guide groove of the substrate corresponds to the groove surface, and the top surface 24 corresponds to the land surface. The same applies to FIGS. 2, 3 and 6 described later. On the other hand, in the substrate 101 of FIGS. 4 and 5, the surface 24 as the bottom surface corresponds to a “land surface”, and the surface 23 as a top surface corresponds to a “groove surface”. This is because, as described later, the order of forming the reflective layer and the recording layer in the information recording medium shown in FIGS. 4 and 5 is opposite to that of the information recording medium shown in FIG. In the recording layer, the recording mark is formed on the surface of the recording layer corresponding to the groove surface (groove recording), is formed on the surface of the recording layer corresponding to the land surface (land recording), or is formed on the groove and land. It is formed on the surface of the recording layer corresponding to both surfaces (land-groove recording). In the embodiment shown in FIG. 1, the step between the groove surface 23 and the land surface 24 of the substrate 1 is preferably 40 nm to 60 nm. Also in the substrate 1 constituting the information recording medium of the embodiments shown in FIGS. 2, 3 and 6 described later, the step between the groove surface 23 and the land surface 24 is preferably within this range. The surface on which the layer is not formed is desirably smooth. Examples of the material of the substrate 1 include a resin such as polycarbonate, amorphous polyolefin or PMMA, or glass. Considering moldability, price, and mechanical strength, polycarbonate is preferably used. In the illustrated embodiment, the thickness of the substrate 1 is about 0.5 to 0.7 mm.

The recording layer 4 is a layer in which a recording mark is formed by causing a phase transformation between a crystalline phase and an amorphous phase by light irradiation or application of electric energy. If the phase transformation is reversible, erasing and rewriting can be performed. As the reversible phase transformation material, Ge-Sb-Te or Ge-Sn-Sb-Te, which is a high-speed crystallization material, is preferably used. Specifically, in the case of Ge—Sb—Te, the composition is preferably a GeTe—Sb ₂ Te ₃ pseudo-binary composition, and in that case, it is preferable that 4Sb ₂ Te ₃ ≦ GeTe ≦ 50 Sb ₂ Te ₃ . In the case of GeTe <4Sb ₂ Te ₃ , the change in the amount of reflected light before and after recording is small, and the quality of the read signal deteriorates. In the case of 50Sb ₂ Te ₃ <GeTe, the volume change between the crystalline phase and the amorphous phase is large, and the rewriting performance is reduced. Ge-Sn-Sb-Te has a higher crystallization rate than Ge-Sb-Te. Ge-Sn-Sb-Te is, for example, those portions of the GeTe-Sb ₂ Te ₃ pseudo-binary composition Ge was replaced with Sn. In the recording layer 4, the Sn content is preferably 20 atomic% or less. If it exceeds 20 at%, the crystallization speed is too high, the stability of the amorphous phase is impaired, and the reliability of the recording mark is reduced. The Sn content can be adjusted according to the recording conditions.

  The recording layer 4 is formed of a Bi-containing material such as Ge-Bi-Te, Ge-Sn-Bi-Te, Ge-Sb-Bi-Te, or Ge-Sn-Sb-Bi-Te. You can also. Bi is easier to crystallize than Sb. Therefore, the crystallization speed of the recording layer can be improved by replacing at least a part of Sb with Bi.

Ge-Bi-Te is a mixture of GeTe and Bi ₂ Te _3. In this mixture, it is preferable that _{8Bi 2 Te 3 ≦ GeTe ≦ 25Bi} 2 Te 3. When GeTe <a 8Bi ₂ Te _3, the crystallization temperature decreases, archival characteristic tends to deteriorate. In the case of 25Bi ₂ Te ₃ <GeTe, the volume change between the crystalline phase and the amorphous phase is large, and the repetitive rewriting performance is reduced.

  Ge-Sn-Bi-Te corresponds to Ge-Bi-Te obtained by substituting a part of Ge for Sn. The crystallization rate can be controlled according to the recording conditions by adjusting the Sn substitution concentration. Sn substitution is more suitable for fine adjustment of the crystallization speed of the recording layer than Bi substitution. In the recording layer, the content of Sn is preferably 10 atomic% or less. If the content exceeds 10 atomic%, the crystallization speed becomes too high, so that the stability of the amorphous phase is impaired and the storage stability of the recording mark is reduced.

Ge-Sn-Sb-Bi-Te is equivalent to Ge-Sb-Te in which part of Ge is replaced with Sn and part of Sb is replaced with Bi. This, GeTe, SnTe, corresponds to a mixture of Sb ₂ Te ₃ and Bi ₂ Te _3. In this mixture, it is possible to control the crystallization speed according to the recording conditions by adjusting the Sn substitution concentration and the Bi substitution concentration. In Ge-Sn-Sb-Bi- Te, it is preferable that _{4 (Sb-Bi) 2 Te} 3 ≦ (Ge-Sn) Te ≦ 25 (Sb-Bi) 2 Te 3. (Ge-Sn) Te <4 (Sb-Bi) For ₂ Te _3, the variation in the amount of reflected light before and after recording is small, the read signal quality is degraded. For _{25 (Sb-Bi) 2 Te} 3 <(Ge-Sn) Te, the volume variation between a crystal phase and an amorphous phase is large, repeated rewriting performance is deteriorated. In the recording layer, the content of Bi is preferably 10 atomic% or less, and the content of Sn is preferably 20 atomic% or less. If the contents of Bi and Sn are within these ranges, good storage stability of the recording mark can be obtained.

  Other materials that cause reversible phase transformation include Ag-In-Sb-Te, Ag-In-Sb-Te-Ge, and Sb-Te containing 70 atomic% or more of Sb.

  As the irreversible phase transformation material, it is preferable to use TeOx + α (α is Pd, Ge, or the like) as disclosed in Japanese Patent Publication No. 7-25209 (Patent No. 2006849). The information recording medium in which the recording layer is an irreversible phase transformation material is of a so-called write-once type in which recording can be performed only once. Even in such an information recording medium, there is a problem that atoms in the dielectric layer diffuse into the recording layer due to heat at the time of recording, thereby deteriorating signal quality. Therefore, the present invention is preferably applied not only to a rewritable information recording medium but also to a write-once type information recording medium.

  When the recording layer 4 is made of a material that undergoes a reversible phase transformation (that is, when the information recording medium is a rewritable information recording medium), as described above, the recording layer 4 The thickness is preferably 15 nm or less, more preferably 12 nm or less.

  As described above, the light absorption correction layer 7 adjusts the ratio Ac / Aa of the light absorption rate Ac when the recording layer 4 is in a crystalline state and the light absorption rate Aa when the recording layer 4 is in an amorphous state, and It has the function of preventing the mark shape from being distorted. The light absorption correction layer 7 is preferably formed of a material having a high refractive index and appropriately absorbing light. For example, the light absorption correction layer 7 can be formed using a material having a refractive index n of 3 or more and 6 or less and an extinction coefficient k of 1 or more and 4 or less. Specifically, amorphous Ge alloys such as Ge—Cr and Ge—Mo, amorphous Si alloys such as Si—Cr, Si—Mo, and Si—W, Te compounds, Ti, Zr , Nb, Ta, Cr, Mo, W, SnTe, PbTe and the like are preferably used. The thickness of the light absorption correction layer 7 is preferably from 20 nm to 80 nm, and more preferably from 30 nm to 50 nm.

  The reflection layer 8 optically increases the amount of light absorbed by the recording layer 4 and thermally rapidly diffuses the heat generated in the recording layer 4 to rapidly cool the recording layer 4 and easily become amorphous. It has the function to do. Further, the reflective layer 8 protects the multilayer film including the recording layer 4 and the dielectric layers 2 and 6 from the use environment. As a material of the reflective layer 8, for example, a simple metal material having a high thermal conductivity such as Al, Au, Ag, and Cu can be used. The reflective layer 8 is selected from the above metal materials for the purpose of improving its moisture resistance and / or for adjusting its thermal conductivity or optical properties (for example, light reflectance, light absorption or light transmittance). It may be formed using a material in which one or more elements to be added and one or more other elements are added. Specifically, an alloy material such as Al-Cr, Al-Ti, Ag-Pd, Ag-Pd-Cu, Ag-Pd-Ti, or Au-Cr can be used. All of these materials are excellent in corrosion resistance and have a rapid cooling function. A similar purpose can be achieved by forming the reflective layer 8 with two or more layers. The thickness of the reflective layer 8 is preferably from 50 to 180 nm, more preferably from 60 to 100 nm.

  In the illustrated information recording medium 25, the bonding layer 9 is provided for bonding the dummy substrate 10 to the reflection layer 8. The adhesive layer 9 may be formed using a material having high heat resistance and adhesiveness, for example, an adhesive resin such as an ultraviolet curable resin. Specifically, the adhesive layer 9 may be formed of a material mainly containing an acrylic resin or a material mainly containing an epoxy resin. If necessary, a protective layer made of an ultraviolet-curable resin and having a thickness of 5 to 20 μm may be provided on the surface of the reflective layer 8 before the formation of the adhesive layer 9. The thickness of the adhesive layer 9 is preferably 15 to 40 μm, and more preferably 20 to 35 μm.

  The dummy substrate 10 enhances the mechanical strength of the information recording medium 25 and protects the laminated body from the first dielectric layer 2 to the reflection layer 8. The preferred material of the dummy substrate 10 is the same as the preferred material of the substrate 1. In the information recording medium 25 to which the dummy substrate 10 is attached, the dummy substrate 10 and the substrate 1 are formed of substantially the same material and have the same thickness so that mechanical warpage, distortion, and the like do not occur. Is preferred.

  The information recording medium according to the first embodiment is a single-sided structure disk having one recording layer. The information recording medium of the present invention may have two recording layers. For example, an information recording medium having a double-sided structure can be obtained by laminating the layers stacked up to the reflective layer 8 in the first embodiment with the reflective layers 8 facing each other with an adhesive layer interposed therebetween. In this case, the bonding of the two laminates is performed by forming an adhesive layer with a slow-acting resin and utilizing the action of pressure and heat. When a protective layer is provided on the reflective layer 8, an information recording medium having a double-sided structure is obtained by laminating a laminate formed up to the protective layer with the protective layers facing each other.

  Subsequently, a method for manufacturing the information recording medium 25 of the first embodiment will be described. In the information recording medium 25, the substrate 1 on which the guide grooves (the groove surface 23 and the land surface 24) are formed is arranged in a film forming apparatus, and the first dielectric layer 2 is formed on the surface of the substrate 1 on which the guide grooves are formed. A step of forming a film (step a), a step of forming a recording layer 4 (step b), a step of forming a second dielectric layer 6 (step c), and a step of forming a light absorption correction layer 7 ( Step d) and the step of forming the reflective layer 8 (step e) are sequentially performed, and further, the step of forming the adhesive layer 9 on the surface of the reflective layer 8 and the step of bonding the dummy substrate 10 are performed. Manufactured. In this specification including the following description, regarding each layer, the term “surface” refers to an exposed surface (surface perpendicular to the thickness direction) when each layer is formed, unless otherwise specified. And

  First, a step a of forming the first dielectric layer 2 on the surface of the substrate 1 on which the guide groove is formed is performed. Step a is performed by sputtering. The sputtering is performed in an Ar gas atmosphere or a mixed gas atmosphere of Ar gas and oxygen using a high frequency power supply.

The sputtering target used in the step a is represented by the above formula (110), that is, represented by (MO ₂ ) _n (Cr ₂ O ₃ ) _100-n (mol%), and M is Hf or Hf and Zr. Yes, one can use a target consisting essentially of a material where n is in the range of 20 ≦ n ≦ 80. According to this target, a layer substantially made of the material represented by the above formula (11) is formed.

Alternatively, the sputtering target is represented by the formula (210), that is, (MO ₂ ) _x (Cr ₂ O ₃ ) _y (SiO ₂ ) _100-xy (mol%), wherein M is Hf or Hf and Zr; x and y may each be in the range of 20 ≦ x ≦ 70 and 20 ≦ y ≦ 60, and may consist essentially of a material where 60 ≦ x + y ≦ 90. According to this target, a layer substantially made of the material represented by the above formula (21) is formed.

Alternatively, the sputtering target is represented by the above formula (220), that is, (MSiO ₄ ) _z (Cr ₂ O ₃ ) _100-z (mol%), M is Hf or Hf and Zr, and z is 25 ≦ It may consist essentially of a material in the range z ≦ 67. According to this target, a layer substantially composed of the material represented by the formula (22) is formed.

Alternatively, the sputtering target is represented by the above formula (30), that is, (MO ₂ ) _c (Cr ₂ O ₃ ) _e (D) _f (SiO ₂ ) _100-cef (mol%), wherein M is Hf or Hf And Zr, D is ZnS, ZnSe or ZnO, and c, e and f are within the range of 20 ≦ c ≦ 60 and 20 ≦ e ≦ 60, 10 ≦ f ≦ 40, and 60, respectively. It may consist essentially of a material with ≦ c + e + f ≦ 90. According to this target, a layer substantially composed of the material represented by the formula (3) is formed.

Alternatively, the sputtering target is represented by the above formula (310), that is, (MSiO ₄ ) _a (Cr ₂ O ₃ ) _b (D) _100-ab (mol%), wherein M is Hf or Hf and Zr; D is ZnS, ZnSe or ZnO, and a and b are respectively in the range of 25 ≦ a ≦ 54 and 25 ≦ b ≦ 63 and substantially consist of a material in which 50 ≦ a + b ≦ 88 It may be. According to this target, a layer substantially made of the material represented by the formula (31) is formed.

Next, the recording layer 4 is formed on the surface of the first dielectric layer 2 by performing Step b. Step b is also performed by sputtering. The sputtering is performed in an Ar gas atmosphere or a mixed gas atmosphere of Ar gas and N ₂ gas using a DC power supply. The sputtering target is Ge-Sb-Te, Ge-Sn-Sb-Te, Ge-Bi-Te, Ge-Sn-Bi-Te, Ge-Sb-Bi-Te, Ge-Sn-Sb-Bi-Te, A material containing any one of Ag-In-Sb-Te and Sb-Te is used. The recording layer 4 after film formation is in an amorphous state.

  Next, the step c is performed to form the second dielectric layer 6 on the surface of the recording layer 4. Step c is performed in the same manner as step a. The second dielectric layer 6 may be formed by using a sputtering target made of a different material from the first dielectric layer 2.

  Next, step d is performed to form the light absorption correction layer 7 on the surface of the second dielectric layer 6. In step d, sputtering is performed using a DC power supply or a high-frequency power supply. As sputtering targets, amorphous Ge alloys such as Ge-Cr and Ge-Mo, amorphous Si alloys such as Si-Cr and Si-Mo, Te compounds, and Ti, Zr, Nb, Ta, Cr, Mo , W, SnTe, PbTe, or the like, and is made of a material selected from crystalline metals, semimetals, and semiconductor materials. The sputtering is generally performed in an Ar gas atmosphere.

  Next, in step e, a reflective layer 8 is formed on the surface of the light absorption correction layer 7. Step e is performed by sputtering. The sputtering is performed in an Ar gas atmosphere using a DC power supply or a high-frequency power supply. As the sputtering target, a sputtering target made of an alloy material such as Al-Cr, Al-Ti, Ag-Pd, Ag-Pd-Cu, Ag-Pd-Ti, or Au-Cr can be used.

  As described above, steps a to e are all sputtering steps. Therefore, the steps a to e may be performed continuously in one sputtering apparatus by sequentially changing the target. Alternatively, steps a to e may be performed using independent sputtering apparatuses.

  After the formation of the reflective layer 8, the substrate 1, which is sequentially laminated from the first dielectric layer 2 to the reflective layer 8, is taken out of the sputtering apparatus. Then, an ultraviolet curable resin is applied to the surface of the reflective layer 8 by, for example, a spin coating method. The dummy substrate 10 is brought into close contact with the applied ultraviolet curable resin, and the resin is cured by irradiating ultraviolet rays from the dummy substrate 10 side, thereby completing the bonding step.

  After the bonding step is completed, an initialization step is performed as necessary. The initialization step is a step in which the recording layer 4 in an amorphous state is crystallized by, for example, irradiating a semiconductor laser to raise the temperature to a temperature higher than the crystallization temperature. The initialization step may be performed before the bonding step. Thus, the information recording medium 25 of the first embodiment can be manufactured by sequentially performing the steps a to e, the step of forming the adhesive layer, and the step of bonding the dummy substrate.

(Embodiment 2)
As Embodiment 2 of the present invention, another example of an optical information recording medium for recording and reproducing information using laser light will be described. FIG. 2 shows a partial cross section of the optical information recording medium.

  The information recording medium 26 shown in FIG. 2 includes a first dielectric layer 2, a recording layer 4, a second interface layer 105, a second dielectric layer 106, a light absorption correction layer 7 on one surface of the substrate 1. , And a reflective layer 8 are formed in this order, and a dummy substrate 10 is bonded by an adhesive layer 9. The information recording medium 26 shown in FIG. 2 is different from the conventional information recording medium 31 shown in FIG. 10 in not having the first interface layer 103. The information recording medium 26 according to the first embodiment shown in FIG. 1 is different from the information recording medium 26 in that the second dielectric layer 106 is laminated on the recording layer 4 via the second interface layer 105. 25. In the information recording medium 26, the first dielectric layer 2 is a Hf / Zr-Cr-O-based material layer or an Hf / Zr-Cr-Zn-O-based material layer as in the first embodiment. . In addition, in FIG. 2, the same reference numerals as those used in FIG. 1 represent the same elements, and are formed by the materials and methods described with reference to FIG. Therefore, detailed description of the elements already described with reference to FIG. 1 will be omitted. In this embodiment, only one interface layer is provided. However, since this interface layer is located between the second dielectric layer 106 and the recording layer 4, for convenience, the “second interface layer” is used. We call it "interface layer."

The information recording medium 26 of this embodiment corresponds to a configuration in which the second dielectric layer 106 is formed of ZnS-20 mol% SiO ₂ used in a conventional information recording medium. Therefore, the second interface layer 105 is provided to prevent mass transfer between the second dielectric layer 106 and the recording layer 4 due to repeated recording. The second interface layer 105 is formed of a nitride such as Si-N, Al-N, Zr-N, Ti-N, Ge-N or Ta-N, a nitride oxide containing these, or a carbide such as SiC. You. Alternatively, the second interface layer 105 may be a Hf / Zr-Cr-O-based material layer or an Hf / Zr-Cr-Zn-O-based material layer. Alternatively, the second interface layer 105 may be a ZrO ₂ —Cr ₂ O ₃ —SiO ₂ material layer formed by mixing a plurality of oxides. The thickness of the interface layer is preferably 1 to 10 nm, more preferably 2 to 7 nm. If the thickness of the interface layer is large, the light reflectivity and light absorbance of the laminated body from the first dielectric layer 2 to the reflective layer 8 formed on the surface of the substrate 1 change, which affects the recording / erasing performance. give.

  Next, a method of manufacturing the information recording medium 26 according to the second embodiment will be described. The information recording medium 26 includes a step of forming the first dielectric layer 2 on the surface of the substrate 1 on which the guide groove is formed (step a), a step of forming the recording layer 4 (step b), and a second step. The step of forming the interface layer 105 (step f), the step of forming the second dielectric layer 106 (step g), the step of forming the light absorption correction layer 7 (step d), and the formation of the reflective layer 8 are performed. It is manufactured by sequentially performing a film forming step (step e), and further performing a step of forming an adhesive layer 9 on the surface of the reflective layer 8 and a step of bonding a dummy substrate 10. Steps a, b, d, and e are as described in relation to the first embodiment, and thus description thereof is omitted here. Hereinafter, only steps that are not performed in the manufacture of the information recording medium according to the first embodiment will be described.

Step f is performed after forming the recording layer 4, and is a step of forming the second interface layer 105 on the surface of the recording layer 4. In step f, sputtering is performed using a high frequency power supply. The sputtering may be, for example, reactive sputtering performed using a sputtering target containing Ge in a mixed gas atmosphere of Ar gas and N ₂ gas. According to this reactive sputtering, an interface layer containing Ge—N is formed on the surface of the recording layer 4.

Next, step g is performed to form a second dielectric layer 106 on the surface of the second interface layer 105. In step g, sputtering is performed in an Ar gas atmosphere or a mixed gas atmosphere of Ar gas and O ₂ gas using a high frequency power supply and a sputtering target made of, for example, ZnS-20 mol% SiO ₂ . Thereby, a layer made of ZnS-20 mol% SiO ₂ is formed. Thereafter, after the step of attaching the dummy substrate 10 is completed, an initialization step is performed as necessary to obtain the information recording medium 26, as described in relation to the first embodiment.

(Embodiment 3)
As Embodiment 3 of the present invention, still another example of an optical information recording medium for recording and reproducing information using laser light will be described. FIG. 3 shows a partial cross section of the optical information recording medium.

  The information recording medium 27 shown in FIG. 3 includes a first dielectric layer 102, a first interface layer 103, a recording layer 4, a second dielectric layer 6, and a light absorption correction layer 7 on one surface of the substrate 1. , And a reflective layer 8 are formed in this order, and a dummy substrate 10 is bonded by an adhesive layer 9. The information recording medium 27 shown in FIG. 3 is different from the conventional information recording medium 31 shown in FIG. 10 in that it does not have the second interface layer 105. The information recording medium 27 according to the first embodiment shown in FIG. 1 is different from the information recording medium 27 in that a first dielectric layer 102 and a first interface layer 103 are laminated in this order between the substrate 1 and the recording layer 4. This is different from the information recording medium 25. In the information recording medium 27, the second dielectric layer 6 is a Hf / Zr-Cr-O-based material layer or an Hf / Zr-Cr-Zn-O-based material layer as in the first embodiment. . In addition, in FIG. 3, the same reference numerals as those used in FIG. 1 represent the same elements, and are formed by the materials and methods described with reference to FIG. Therefore, detailed description of the elements already described in FIG. 1 will be omitted.

The information recording medium 27 of this embodiment corresponds to a configuration in which the first dielectric layer 102 is formed of ZnS-20 mol% SiO ₂ used in a conventional information recording medium. Therefore, the first interface layer 103 is provided to prevent mass transfer between the first dielectric layer 102 and the recording layer 4 due to repeated recording. The preferred material and thickness of the first interface layer 103 are the same as those of the second interface layer 105 of the information recording medium 26 of the second embodiment described with reference to FIG. Therefore, a detailed description thereof will be omitted.

  Next, a method of manufacturing the information recording medium 27 according to the third embodiment will be described. In the information recording medium 27, a step of forming the first dielectric layer 102 on the surface of the substrate 1 on which the guide groove is formed (Step h), a step of forming the first interface layer 103 (Step i), The step of forming the recording layer 4 (step b), the step of forming the second dielectric layer 6 (step c), the step of forming the light absorption correction layer 7 (step d), and the formation of the reflective layer 8 are performed. It is manufactured by sequentially performing a film forming step (step e), and further performing a step of forming an adhesive layer 9 on the surface of the reflective layer 8 and a step of bonding a dummy substrate 10. Steps b, c, d, and e are the same as those described in relation to the first embodiment, and a description thereof will be omitted. Hereinafter, only steps that are not performed in the manufacture of the information recording medium according to the first embodiment will be described.

  Step h is a step of forming the first dielectric layer 102 on the surface of the substrate 1. The specific method is the same as the step g described in relation to the manufacturing method of the second embodiment. Step i is a step of forming a first interface layer 103 on the surface of the first dielectric layer 102. The specific method is the same as the step f described in relation to the manufacturing method of the second embodiment. Thereafter, after the step of attaching the dummy substrate 10 is completed, an initialization step is performed as necessary, as described in relation to the first embodiment, to obtain the information recording medium 27.

(Embodiment 4)
As Embodiment 4 of the present invention, still another example of an optical information recording medium for recording and reproducing information using laser light will be described. FIG. 4 shows a partial cross section of the optical information recording medium.

  The information recording medium 28 shown in FIG. 4 has a reflective layer 8, a second dielectric layer 6, a recording layer 4, and a first dielectric layer 2 formed in this order on one surface of a substrate 101, and further has an adhesive layer. 9 has a configuration in which the dummy substrate 110 is bonded. This information recording medium 28 differs from the conventional information recording medium 31 shown in FIG. 10 in that it does not have the first interface layer 103 and the second interface layer 105. The information recording medium having this configuration is different from the information recording medium 25 having the configuration shown in FIG. 1 in that the information recording medium has no light absorption correction layer 7.

  The laser beam 12 is incident on the information recording medium 28 having this configuration from the dummy substrate 110 side, thereby recording and reproducing information. In order to increase the recording density of the information recording medium, it is necessary to use a short-wavelength laser beam and further narrow the laser beam to form a small recording mark on the recording layer. In order to narrow the beam, it is necessary to further increase the numerical aperture NA of the objective lens. However, as the NA increases, the focal position becomes shallower. Therefore, it is necessary to make the substrate on which the laser light is incident thin. In the information recording medium 28 shown in FIG. 4, the dummy substrate 110 on the side where the laser beam is incident does not need to function as a support when forming a recording layer or the like, so that its thickness can be reduced. . Therefore, according to this configuration, it is possible to obtain a large-capacity information recording medium 28 capable of recording at higher density. Specifically, according to this configuration, it is possible to obtain an information recording medium having a capacity of 25 GB, which uses a blue-violet laser beam having a wavelength of about 405 nm for recording and reproduction.

  Also in this information recording medium, the first and second dielectric layers 2 and 6 are made of Hf / Zr—Cr—O-based material layer or Hf / Zr—Cr—Zn—O, as in the first embodiment. This is a system material layer. The Hf / Zr-Cr-O-based material layer and the Hf / Zr-Cr-Zn-O-based material layer are applied as dielectric layers irrespective of the formation order of the reflective layer and the like and the recording capacity. The materials included in the Hf / Zr-Cr-O-based material layer and the Hf / Zr-Cr-Zn-O-based material layer are as described in connection with Embodiment 1, and therefore, detailed descriptions thereof are given. Description is omitted.

  As described above, this information recording medium 28 is suitable for recording and reproducing with a laser beam having a short wavelength. Therefore, the thicknesses of the first and second dielectric layers 2 and 6 are determined from, for example, a preferable optical path length when λ = 405 nm. In order to increase the reproduction signal amplitude of the recording mark of the information recording medium 28 and improve the signal quality, for example, the first dielectric layer 2 and the second dielectric layer 20 satisfy the conditions of 20% ≦ Rc and Ra ≦ 5%. The optical path length nd of the body layer 6 was strictly determined by calculation based on the matrix method. As a result, the Hf / Zr-Cr-O-based material layer or the Hf / Zr-Cr-Zn-O-based material layer having the above-described refractive index is used as the first and second dielectric layers 2 and 6. In this case, it was found that the thickness of the first dielectric layer 2 was preferably 30 nm to 100 nm, and more preferably 50 nm to 80 nm. Further, it has been found that the thickness of the second dielectric layer 6 is preferably 3 nm to 50 nm, and more preferably 10 nm to 30 nm.

  The substrate 101 is a transparent disk-shaped plate, like the substrate 1 of the first embodiment. A guide groove for guiding laser light may be formed on the surface of the substrate 101 on which the reflection layer or the like is formed. When the guide groove is formed, as described with reference to the first embodiment, the surface 23 on the side closer to the laser beam 12 is called a groove surface 23 for convenience, and the surface 24 on the side farther from the laser beam 12. Is called a land surface for convenience. In the substrate 101, the step between the groove surface 23 and the land surface 24 is preferably 10 nm to 30 nm, and more preferably 15 nm to 25 nm. The surface on which the layer is not formed is desirably smooth. As the material of the substrate 101, the same material as the material of the substrate 1 of the first embodiment can be used. The thickness of the substrate 101 is preferably about 1.0 to 1.2 mm. The preferred thickness of the substrate 101 is larger than that of the substrate 1 of the first embodiment. This is because the thickness of the dummy substrate 110 is small and the substrate 101 needs to secure the strength of the information recording medium, as described later.

  Like the substrate 101, the dummy substrate 110 is a transparent disk-shaped plate. As described above, according to the configuration shown in FIG. 4, by making the thickness of the dummy substrate 110 small, it becomes possible to perform recording with a short-wavelength laser beam. Therefore, it is preferable that the thickness of the dummy substrate 110 be 40 μm to 110 μm. More preferably, the total thickness of the adhesive layer 9 and the dummy substrate 110 is 50 μm to 120 μm.

  Since the dummy substrate 110 is thin, it is preferably formed of a resin such as polycarbonate, amorphous polyolefin, or PMMA, and particularly preferably formed of polycarbonate. In addition, since the dummy substrate 110 is located on the side where the laser beam 12 is incident, it is optically preferable that the birefringence in a short wavelength region is small.

  The adhesive layer 9 is preferably formed of a transparent ultraviolet curable resin. The thickness of the adhesive layer 9 is preferably 5 to 15 μm. If the adhesive layer 9 has the function of the dummy substrate 110 and can be formed to have a thickness of 50 μm to 120 μm, the dummy substrate 110 can be omitted.

  Other elements denoted by the same reference numerals as those in the first embodiment are the same as those already described in relation to the first embodiment, and a description thereof will not be repeated.

In a modification of the information recording medium of this embodiment, for example, only the first dielectric layer is an Hf / Zr-Cr-O-based material layer or an Hf / Zr-Cr-Zn-O-based material layer; Can be formed of ZnS-20 mol% SiO ₂ to form a second interface layer between the second dielectric layer and the recording layer. In another modification of the information recording medium of this embodiment, only the second dielectric layer is a Hf / Zr-Cr-O-based material layer or an Hf / Zr-Cr-Zn-O-based material layer, The first interface layer may be formed between the first dielectric layer and the recording layer by using the first dielectric layer as ZnS-20 mol% SiO ₂ .

  Next, a method of manufacturing the information recording medium 28 according to the fourth embodiment will be described. In the information recording medium 28, a step of arranging the substrate 101 on which the guide grooves (the groove surface 23 and the land surface 24) are formed in a film forming apparatus and forming the reflective layer 8 on the surface of the substrate 101 on which the guide grooves are formed (Step e), a step of forming the second dielectric layer 6 (step c), a step of forming the recording layer 4 (step b), and a step of forming the first dielectric layer 2 (step a) is sequentially performed, and further, a step of forming the adhesive layer 9 on the surface of the first dielectric layer 2 and a step of bonding the dummy substrate 110 are performed.

  First, the step e is performed to form the reflective layer 8 on the surface of the substrate 101 on which the guide groove is formed. A specific method of performing the step e is as described in relation to the first embodiment. Next, step c, step b, and step a are performed in this order. A specific method for performing steps c, b, and a is as described in relation to the first embodiment. In the method for manufacturing an information recording medium according to this embodiment, the order of performing the steps is different from that in the method for manufacturing an information recording medium according to the first embodiment. As in the case of manufacturing the information recording medium of Embodiment 1, the sputtering target used in step c may be different from the sputtering target used in step a.

  After the first dielectric layer 2 is formed, the substrate 101 on which the reflective layer 8 and the first dielectric layer 2 are sequentially stacked is taken out of the sputtering apparatus. Then, an ultraviolet curable resin is applied on the first dielectric layer 2 by, for example, a spin coating method. The dummy substrate 110 is brought into close contact with the applied ultraviolet curable resin, and the resin is cured by irradiating ultraviolet rays from the dummy substrate 110 side, and the bonding step is completed. The step of bonding the dummy substrate 110 can be omitted by forming the adhesive layer 9 so as to have a thickness of 60 μm to 120 μm and irradiating it with ultraviolet light.

  After the bonding step is completed, an initialization step is performed as necessary. The method of the initialization step is as described in relation to the first embodiment.

(Embodiment 5)
As Embodiment 5 of the present invention, still another example of an optical information recording medium that performs recording and reproduction using laser light will be described. FIG. 5 shows a partial cross section of the optical information recording medium.

  In the information recording medium 29 shown in FIG. 5, a second information layer 22, an intermediate layer 16, and a first information layer 21 are formed in this order on one surface of a substrate 101, and a dummy substrate 110 is formed via an adhesive layer 9. This is a stacked configuration. More specifically, the second information layer 22 includes a second reflective layer 20, a fifth dielectric layer 19, a second recording layer 18, and a fourth dielectric layer 17 on one surface of the substrate 101. It is formed in order. The intermediate layer 16 is formed on the surface of the fourth dielectric layer 17. The first information layer 21 includes a third dielectric layer 15, a first reflective layer 14, a second dielectric layer 6, a first recording layer 13, and a first dielectric layer 15 on the surface of the intermediate layer 16. The body layer 2 is formed in this order. Also in this embodiment, the laser light 12 is incident from the dummy substrate 110 side. In the information recording medium of this embodiment, information can be recorded on each of the two recording layers. Therefore, according to this configuration, it is possible to obtain an information recording medium having about twice the capacity of the fourth embodiment. Specifically, according to this configuration, it is possible to obtain an information recording medium having a capacity of 50 GB, which uses, for example, laser light in a blue-violet region near a wavelength of 405 nm for recording and reproduction.

  Recording and reproduction on the first information layer 21 are performed by the laser beam 12 that has passed through the dummy substrate 110. Recording and reproduction in the second information layer 22 are performed by the laser beam 12 that has passed through the dummy substrate 110, the first information layer 21, and the intermediate layer 16.

  In the information recording medium 29 of the embodiment shown in FIG. 5, the fifth dielectric layer 19, the fourth dielectric layer 17, the second dielectric layer 6, and the first dielectric layer 2 are all Hf. It is preferably a / Zr-Cr-O-based material layer or a Hf / Zr-Cr-Zn-O-based material layer. If these material layers are used, the first recording layer 13 and the first dielectric layer 2, the first recording layer 13 and the second dielectric layer 6, the second recording layer An interface layer between the second recording layer 18 and the fifth dielectric layer 19 and an interface layer between the second recording layer 18 and the fifth dielectric layer 19 become unnecessary. The specific material of the Hf / Zr-Cr-O-based material layer or the Hf / Zr-Cr-Zn-O-based material layer is as described in connection with Embodiment 1, and thus the details thereof are described. Detailed description is omitted.

The fifth dielectric layer 19 and the second dielectric layer 6 function as a heat insulating layer between the reflective layer and the recording layer. Therefore, the fifth and second dielectric layers 19 and 6 are made of a material represented by the formula (MO ₂ ) _X (Cr ₂ O ₃ ) _Y (SiO ₂ ) _100-XY (ie, the formula (21)) Alternatively, a layer substantially composed of a material represented by the formula (MO ₂ ) _C (Cr ₂ O ₃ ) _E (D) _F (SiO ₂ ) _100-CEF (that is, the formula (3)) is preferable. The thickness of the fifth and second dielectric layers 19 and 6 is preferably 3 nm to 50 nm, more preferably 10 nm to 30 nm.

  In the second information layer 22 and the first information layer 21, before reaching the second recording layer 18 and the first recording layer 13, the laser beam 12 emits the fourth dielectric layer 17 and the first dielectric layer 17. It is incident on layer 2. Therefore, it is desirable that the fourth and first dielectric layers 17 and 2 are made of a transparent material having low thermal conductivity. Such a material is a material represented by the above formulas (21) and (3). The thickness of the fourth and first dielectric layers 17 and 2 is preferably 30 nm to 100 nm, more preferably 50 nm to 80 nm.

  As described above, also in the information recording medium having the single-sided two-layer structure as shown in FIG. 5, the dielectric layers located on both sides of the recording layer are formed of the Hf / Zr-Cr-O-based material layer or the Hf / Zr-Cr- By using a Zn—O-based material layer, the dielectric layer can be formed so as to be in direct contact with the recording layer without interposing an interface layer. Therefore, according to the present invention, the number of layers constituting the entire information recording medium having a single-sided two-layer structure can be reduced. In addition, by using the specific material layer as the dielectric layer, the refractive index and the recording sensitivity of the medium can be adjusted and optimized according to the type of the information recording medium.

The third dielectric layer 15 is located between the intermediate layer 16 and the first reflective layer 14. The third dielectric layer 15 is preferably transparent and has a high refractive index so as to have a function of increasing the light transmittance of the first information layer 21. Further, like the reflective layer, the third dielectric layer 15 is preferably made of a material having a higher thermal conductivity so as to have a function of quickly diffusing the heat of the first recording layer 13. Materials satisfying these conditions is Cr ₂ O ₃ based material containing TiO ₂ based materials and Cr ₂ O ₃ containing TiO _2. Specifically, the TiO ₂ -based material (or Cr ₂ O ₃ -based material) is a material containing TiO ₂ (or Cr ₂ O ₃ ) in an amount of 50 mol% or more. The TiO ₂ -based material (or Cr ₂ O ₃ -based material) contains TiO ₂ (or Cr ₂ O ₃ ) preferably at least 80 mol%, more preferably at least 90 mol%. Further, a material represented by (MO ₂ ) _N (Cr ₂ O ₃ ) _100-N (that is, the formula (11)) is also preferably used. When the third dielectric layer 15 is formed of the material represented by the formula (11), the thermal conductivity is adjusted by changing the composition under the condition that the ratio of Cr ₂ O ₃ is 40 mol% or more. Is preferred. When a TiO ₂ -based material, Cr ₂ O ₃ -based material, or (MO ₂ ) _N (Cr ₂ O ₃ ) _100-N is used, a layer having a large refractive index of 2.4 to 2.8 can be obtained. The thickness of the third dielectric layer 15 is preferably 10 nm to 30 nm.

  The substrate 101 is similar to the substrate 101 of the fourth embodiment. Therefore, a detailed description of the substrate 101 is omitted here.

  The second reflection layer 20 is the same as the reflection layer 8 of the first embodiment. Further, the second recording layer 18 is the same as the recording layer 4 of the first embodiment. Therefore, a detailed description of the second reflective layer 20 and the second recording layer 18 is omitted here.

The intermediate layer 16 is provided so that the focal position of the laser beam in the first information layer 21 and the focal position in the second information layer 22 are significantly different. Guide grooves are formed in the intermediate layer 16 on the first information layer 21 side as necessary. The intermediate layer 16 can be formed of an ultraviolet curable resin. The intermediate layer 16 is desirably transparent to light having a wavelength λ for recording and reproduction so that the laser light 12 efficiently reaches the second information layer 22. The thickness of the intermediate layer 16 needs to be not less than the depth of focus ΔZ determined by the numerical aperture NA of the objective lens and the wavelength λ of the laser beam. ΔZ can be approximated by ΔZ = λ / {2 (NA) ² }. When λ = 405 nm and NA = 0.85, ΔZ = 0.28 μm. Further, since the range of ± 0.3 μm of this value is included in the range of the depth of focus, the intermediate layer 16 needs to have a thickness of 0.8 μm or more. Also, the thickness of the intermediate layer 16 is set so that the distance between the first recording layer 13 of the first information layer 21 and the second recording layer 18 of the second information layer 22 is within the range where the objective lens can collect light. As described above, it is preferable that the thickness of the dummy substrate 110 be set within an allowable substrate thickness tolerance for the objective lens used. Therefore, the thickness of the intermediate layer is preferably 10 μm to 40 μm.

  The intermediate layer 16 may be formed by laminating a plurality of resin layers as necessary. Specifically, it may have a two-layer structure of a layer for protecting the fourth dielectric layer 17 and a layer having a guide groove.

  The first reflection layer 14 has a function of quickly diffusing the heat of the first recording layer 13. When recording and reproducing the second information layer 22, the laser beam 12 transmitted through the first information layer 21 is used. Therefore, the first information layer 21 needs to have a high light transmittance as a whole, and is preferably used. Has a light transmittance of 45% or more. Therefore, the material and thickness of the first reflective layer 14 are limited as compared with the second reflective layer 20. In order to reduce the light absorption of the first reflective layer 14, it is desirable that the first reflective layer 14 has a small thickness, a small extinction coefficient, and a large thermal conductivity. Specifically, the first reflective layer 14 is preferably made of an alloy containing Ag and has a thickness of 5 nm or more and 15 nm or less.

The material and thickness of the first recording layer 13 are also limited as compared with the second recording layer 18 in order to ensure a high light transmittance of the first information layer 21. The first recording layer 13 is preferably formed such that the average of the transmittance in the crystalline phase and the transmittance in the amorphous phase is 45% or more. Therefore, the thickness of the first recording layer 13 is preferably set to 7 nm or less. Even if the material of the first recording layer 13 has such a small film thickness, a good recording mark is formed by melting and quenching, and a high-quality signal can be reproduced. Is selected to ensure that the can be erased. Specifically, a part of Ge of Ge-Sb-Te or GeTe-Sb ₂ Te ₃ based materials, such as GeTe-Sb ₂ Te ₃ based material is a reversible phase change materials were replaced with Sn Ge- It is preferable to form the first recording layer 13 of Sn-Sb-Te. Ge-Bi-Te, or a part of Ge of Ge-Bi-Te may be used Ge-Sn-Bi-Te obtained by substituting Sn such as GeTe-Bi ₂ Te ₃ based materials.

  The adhesive layer 9 is preferably formed of a transparent ultraviolet curable resin, similarly to the adhesive layer 9 of the fourth embodiment. The thickness of the adhesive layer 9 is preferably 5 to 15 μm.

  The dummy substrate 110 is similar to the dummy substrate 110 of the fourth embodiment. Therefore, a detailed description of the dummy substrate is omitted here. Also in this embodiment, if the adhesive layer 9 also has the function of the dummy substrate 110 and can be formed to have a thickness of 50 μm to 120 μm, the dummy substrate 110 can be omitted.

  In the information recording medium of this embodiment, only one of the first dielectric layer 2, the second dielectric layer 6, the fourth dielectric layer 17, and the fifth dielectric layer 19 is used. May be a Hf / Zr-Cr-O-based material layer or a Hf / Zr-Cr-Zn-O-based material layer. Alternatively, two or three dielectric layers may be Hf / Zr-Cr-O-based material layers or Hf / Zr-Cr-Zn-O-based material layers, respectively. When one dielectric layer is any one of these two material layers, at least one interface layer becomes unnecessary, and when two dielectric layers are any one of these two material layers. Does not require at least two interface layers. Therefore, in the information recording medium of this embodiment, up to four interface layers can be eliminated. If necessary, an interface layer for preventing mass transfer between the recording layer and the dielectric layer is provided between the recording layer and a dielectric layer other than the Hf / Zr-Cr-O-based material layer. Good.

  In the above, the information recording medium having the configuration having two information layers having the recording layer has been described. The information recording medium having a plurality of recording layers is not limited to this configuration, and may have a configuration including three or more information layers. In a modification of the illustrated embodiment, for example, one of two information layers is an information layer having a recording layer that causes a reversible phase transformation, and one is an information layer that has a recording layer that causes an irreversible phase transformation. It is a layer.

  In an information recording medium having three information layers, one of the three information layers is a read-only information layer, one is an information layer having a recording layer that causes a reversible phase transformation, and one is An information layer having a recording layer that causes irreversible phase transformation is also possible. As described above, there are various types of information recording media having two or more information layers. In any of the embodiments, the interface between the recording layer and the dielectric layer is achieved by forming the dielectric layer as a Hf / Zr-Cr-O-based material layer or an Hf / Zr-Cr-Zn-O-based material layer. The need for providing a layer can be eliminated. In an information recording medium having two or more information layers, the dielectric layer in contact with the recording layer may be an Hf-Zr-Cr-Zn-O-based material layer.

  Next, a method of manufacturing the information recording medium 29 according to the fifth embodiment will be described. The information recording medium 29 includes a step of forming a second reflective layer 20 on the substrate 101 (step j), a step of forming a fifth dielectric layer 19 (step k), and a second recording layer 18. After sequentially performing the film forming step (step 1) and the step of forming the fourth dielectric layer 17 (step m), a step of forming the intermediate layer 16 on the surface of the fourth dielectric layer 17 is performed. Then, a step of forming the third dielectric layer 15 on the surface of the intermediate layer 16 (step n), a step of forming the first reflective layer 14 (step o), and a step of forming the second dielectric layer 6 are performed. The step of forming a film (step p), the step of forming a first recording layer 13 (step q), and the step of forming a first dielectric layer 2 (step r) are sequentially performed. By performing the step of forming the adhesive layer 9 on the surface of the first dielectric layer 2 and the step of bonding the dummy substrate 110, That.

  Steps j to m correspond to the step of forming the second information layer 22. Step j is a step of forming the second reflective layer 20 on the surface of the substrate 101 on which the guide groove is formed. Step j is performed in the same manner as in step e of the first embodiment. Next, a process k is performed to form a fifth dielectric layer 19 on the surface of the second reflective layer 20. Step k is performed in the same manner as step c of the first embodiment. Next, Step 1 is performed to form a second recording layer 18 on the surface of the fifth dielectric layer 19. Step 1 is performed in the same manner as step b of the first embodiment. Finally, the step m is performed to form the fourth dielectric layer 17 on the surface of the second recording layer 18. Step m is performed in the same manner as step a of the first embodiment.

  The substrate 101 on which the second information layer 22 has been formed in steps j to m is taken out of the sputtering apparatus, and the intermediate layer 16 is formed. The intermediate layer 16 is formed by the following procedure. First, an ultraviolet curable resin is applied to the surface of the fourth dielectric layer 17 by, for example, spin coating. Next, the uneven surface of the polycarbonate substrate having unevenness complementary to the guide groove to be formed in the intermediate layer is brought into close contact with the ultraviolet curable resin. After the resin is cured by irradiating ultraviolet rays in that state, the polycarbonate substrate on which the guide grooves are formed is peeled off. Thereby, a guide groove having a shape complementary to the irregularities is formed in the ultraviolet curable resin, and the intermediate layer 16 having the guide groove as illustrated is formed. Alternatively, the intermediate layer 16 may be formed by forming a layer for protecting the fourth dielectric layer 17 with an ultraviolet curable resin, and forming a layer having a guide groove thereon. In that case, the resulting intermediate layer has a two-layer structure. Alternatively, the intermediate layer may be formed by laminating three or more layers.

  The substrate 101 formed up to the intermediate layer 16 is placed in the sputtering apparatus again, and the first information layer 21 is formed on the surface of the intermediate layer 16. The step of forming the first information layer 21 corresponds to steps n to r.

Step n is a step of forming the third dielectric layer 15 on the surface of the intermediate layer 16 having the guide groove. In step n, sputtering is performed in an Ar gas atmosphere or a mixed gas atmosphere of Ar gas and O ₂ gas using a high frequency power supply and a sputtering target made of a TiO ₂ material or a Cr ₂ O ₃ material. carry out. Alternatively, in the step n, sputtering may be performed in an Ar gas atmosphere using a sputtering target composed of a mixture of HfO ₂ and Cr ₂ O ₃ or a mixture of HfO ₂ , ZrO ₂ and Cr ₂ O ₃ . Alternatively, in step n, reactive sputtering may be performed in a mixed gas atmosphere of Ar gas and O ₂ gas using a sputtering target made of Ti or Cr.

  Next, step o is performed to form the first reflective layer 14 on the surface of the third dielectric layer 15. In step o, sputtering is performed in an Ar gas atmosphere using a direct current power source and a sputtering target of an alloy containing Ag.

  Next, the step p is performed to form the second dielectric layer 6 on the surface of the first reflection layer 14. Step p is performed in the same manner as step k.

Next, step q is performed to form the first recording layer 13 on the surface of the second dielectric layer 6. In step q, a DC power supply is used, and Ge-Sb-Te, Ge-Sn-Sb-Te, Ge-Bi-Te, Ge-Sn-Bi-Te, Ge-Sb-Bi-Te, and Ge-Sb-Te are used. Sputtering is performed in an Ar gas atmosphere or a mixed gas atmosphere of Ar gas and N ₂ gas using a sputtering target containing any one material selected from Sn—Sb—Bi—Te.

  Next, a process r is performed to form the first dielectric layer 2 on the surface of the first recording layer 13. Step r is performed in the same manner as in step m. In this manner, the first information layer 21 is formed by sequentially performing the steps n to r.

  The substrate 101 formed up to the first information layer 21 is taken out of the sputtering device. Then, an ultraviolet curable resin is applied to the surface of the first dielectric layer 2 by, for example, a spin coating method. The dummy substrate 110 is brought into close contact with the applied ultraviolet curable resin, and the resin is cured by irradiating ultraviolet rays from the dummy substrate 110 side, and the bonding step is completed. Also in the method for manufacturing an information recording medium according to the fifth embodiment, the step of bonding the dummy substrate 110 can be omitted in the same manner as the method for manufacturing the information recording medium according to the fourth embodiment.

  After the bonding step is completed, an initialization step for the second information layer 22 and the first information layer 21 is performed as necessary. The initialization process may be performed on the second information layer 22 before or after forming the intermediate layer, and may be performed on the first information layer 21 before or after the bonding process of the dummy substrate 110. The method of performing the initialization step is as described in relation to the first embodiment.

(Embodiment 6)
As Embodiment 6 of the present invention, still another example of an information recording medium for recording and reproducing information by using a laser beam will be described. FIG. 6 shows a partial cross section of the optical information recording medium.

  The information recording medium 30 shown in FIG. 6 includes a first dielectric layer 102, a first interface layer 3, a recording layer 4, a second interface layer 5, and a second dielectric layer on one surface of the substrate 1. 106, a light absorption correction layer 7, and a reflection layer 8 are formed in this order, and further, a dummy substrate 10 is bonded with an adhesive layer 9. In the information recording medium 30 shown in FIG. 6, the first and second interface layers 3 and 5 are Hf / Zr-Cr-O-based material layers or Hf / Zr-Cr-Zn-O-based material layers. . In addition, in FIG. 6, the same reference numerals as those used in FIG. 1 represent the same elements, and are formed by the materials and methods described with reference to FIG. Therefore, detailed description of the elements already described with reference to FIG. 1 will be omitted.

This type of information recording medium corresponds to a configuration in which the first and second dielectric layers 102 and 106 are formed of ZnS-20 mol% SiO ₂ used in a conventional information recording medium. In such a configuration, an Hf / Zr-Cr-O-based material layer or an Hf / Zr-Cr-Zn-O-based material layer can be used as the first and second interface layers 3 and 5. Preferred materials of the first and second interface layers 3 and 5 are the same as those of the first and second dielectric layers 2 and 6 of the first embodiment. Therefore, a detailed description thereof will be omitted. The thickness of the first and second interface layers 3 and 5 is preferably 1 to 10 nm, more preferably about 2 to 7 nm, so as not to affect the recording / erasing performance. The interface layer, which is an Hf / Zr—Cr—O-based material layer or an Hf / Zr—Cr—Zn—O-based material layer, has a lower material cost than a conventional interface layer made of a nitride containing Ge. It has certain advantages such as a small extinction coefficient (high transparency), and a high melting point and thermal stability.

  Next, a method of manufacturing the information recording medium 30 according to the sixth embodiment will be described. In the information recording medium 30, a step of forming the first dielectric layer 102 on the surface of the substrate 1 on which the guide groove is formed (step h), a step of forming the first interface layer 3 (step s), A step of forming the recording layer 4 (step b), a step of forming the second interface layer 5 (step t), a step of forming the second dielectric layer 106 (step g), a light absorption correction layer 7 (step d) and a step of forming the reflective layer 8 (step e) are sequentially performed, and further, a step of forming an adhesive layer 9 on the surface of the reflective layer 8 and bonding the dummy substrate 10 It is manufactured by performing the steps. Steps b, d and e are as described in relation to the first embodiment, step g is as described in relation to the second embodiment, and step h is related to the third embodiment. Since it is as described, the description is omitted here.

  Step s is a step of forming the first interface layer 3 on the surface of the first dielectric layer 102. Step s is performed in the same manner as in step a of the first embodiment. Step t is a step of forming the second interface layer 5 on the surface of the recording layer 4. Step t is performed in the same manner as step c of the first embodiment.

  As described above, with reference to FIGS. 1 to 6, an optical information recording medium that records and reproduces with a laser beam has been described as an embodiment of the information recording medium of the present invention. The optical information recording medium of the present invention is not limited to these modes. The optical information recording medium of the present invention is provided with an Hf / Zr-Cr-O-based material layer or an Hf / Zr-Cr-Zn-O-based material layer as one of the constituent layers, preferably in contact with the recording layer. As long as it is, it can take any form. Further, the optical information recording medium of the present invention is suitable for recording at various wavelengths. Therefore, the optical information recording medium of the present invention is, for example, a DVD-RAM or DVD-R for recording / reproducing with a laser beam having a wavelength of 630 to 680 nm, or a large capacity optical disc for recording / reproducing with a laser beam having a wavelength of 400 to 450 nm. May be.

  The information recording medium of the present invention may be a read-only medium. Such a medium is usually produced by forming signal pits corresponding to information on a substrate and forming a reflective layer thereon, and reproducing the information involves reducing the optical path difference of the reflected light between the pits and other parts. Read and do. Therefore, the recording layer as shown in FIGS. 1 to 6 does not exist in the read-only medium. In such a medium, the Hf / Zr—Cr—O-based material layer is provided, for example, so as to be in contact with one or both surfaces of the reflective layer to protect the reflective layer from moisture and / or to reflect the reflective layer. Can be used to adjust the reflectivity of light.

(Embodiment 7)
Embodiment 7 As Embodiment 7 of the present invention, an example of an information recording medium on which information is recorded and reproduced by applying electric energy will be described. FIG. 8 shows a partial cross section of the information recording medium.

  FIG. 8 shows a memory 207 in which a lower electrode 202, a recording unit 203, and an upper electrode 204 are formed on a surface of a substrate 201 in this order. The recording unit 203 of the memory 207 has a configuration including a cylindrical recording layer 205 and a dielectric layer 206 surrounding the recording layer 205. Unlike the optical information recording medium described above with reference to FIGS. 1 to 6, in the memory 207 of this embodiment, the recording layer 205 and the dielectric layer 206 are formed on the same surface, and they are stacked. No relationship. However, since both the recording layer 205 and the dielectric layer 206 form part of the laminated body including the substrate 201, the lower and upper electrodes 202 and 204 in the memory 207, they can be called "layers". It is. Therefore, the information recording medium of the present invention includes a medium in which the recording layer and the dielectric layer are on the same surface.

As the substrate 201, specifically, a semiconductor substrate such as a Si substrate, or an insulating substrate such as a polycarbonate substrate, a SiO ₂ substrate, and an Al ₂ O ₃ substrate can be used as the substrate 201. The lower electrode 202 and the upper electrode 204 are formed of a suitable conductive material. The lower electrode 202 and the upper electrode 204 are formed by, for example, sputtering a metal such as Au, Ag, Pt, Al, Ti, W, and Cr, and a mixture thereof.

The recording layer 205 included in the recording unit 203 is made of a material that changes phase when electric energy is applied, and may be referred to as a phase change unit. The recording layer 205 is formed of a material that changes phase between a crystalline phase and an amorphous phase by Joule heat generated by applying electric energy. Examples of the material of the recording layer 205 include Ge-Sb-Te, Ge-Sn-Sb-Te, Ge-Bi-Te, Ge-Sn-Bi-Te, Ge-Sb-Bi-Te, and Ge-Sn- Sb-Bi-Te-based material is used, more specifically, GeTe-Sb ₂ Te ₃ system or GeTe-Bi ₂ Te ₃ based material is used.

  By applying a voltage between the upper electrode 204 and the lower electrode 202, the dielectric layer 206 constituting the recording section 203 prevents the current flowing through the recording layer 205 from escaping to the peripheral portion, and Has the function of electrically and thermally insulating the. Therefore, the dielectric layer 206 can also be called a heat insulating part. The dielectric layer 206 is a Hf / Zr-Cr-O-based material layer or a Hf / Zr-Cr-Zn-O-based material layer, and specifically, the formulas (1), (11), and (2). , (21), (22), (3) or (31). The Hf / Zr—Cr—O-based material layer and the Hf / Zr—Cr—Zn—O-based material layer have a high melting point, atoms are hardly diffused even when heated, and thermal conductivity is high. It is preferably used because of its low rate.

  The memory 207 will be further described along with an operation method thereof in an embodiment described later.

(Test 1)
First, the nominal composition of the Hf—Cr—O-based sputtering target used in the method of manufacturing the information recording medium of the present invention (in other words, the composition that is publicly indicated by the target maker during supply), its analytical composition, and The relationship between the analytical compositions of the Hf—Cr—O-based material layers obtained using the target was confirmed by a test.

で公称組成が表記され、ｎの値の異なる（ｎ＝２０および８０）２種類のスパッタリングターゲットを粉末状にし、Ｘ線マイクロアナライザ−法により組成分析を行った。この結果、スパッタリングターゲットの分析組成が、化合物基準（本試験では酸化物基準）の式（１１０）ではなく、元素基準の式（１０）：

で得られた。得られたターゲットの分析組成を表１に示す。さらに、この公称組成に基づいて、元素基準での換算組成（原子％）を理論計算により求めた。計算した換算組成（原子％）を表１に付記する。 In this test, the composition of a sputtering target composed of a HfO ₂ —Cr ₂ O ₃ material, which is one of the Hf—Cr—O materials, was analyzed, and the difference between the nominal composition and the analyzed composition was examined. More specifically, the following formula where M is Hf in formula (110):

, Two types of sputtering targets having different values of n (n = 20 and 80) were powdered, and the composition was analyzed by an X-ray microanalyzer method. As a result, the analysis composition of the sputtering target is not the compound-based (oxide-based) formula (110) but the element-based formula (10):

Was obtained. Table 1 shows the analytical composition of the obtained target. Further, based on the nominal composition, a reduced composition (atomic%) on an element basis was obtained by theoretical calculation. Table 1 shows the calculated reduced composition (atomic%).

As shown in Table 1, as a result of analyzing the powder of the sputtering target whose nominal composition is expressed by the formula (110) of (HfO ₂ ) _n (Cr ₂ O ₃ ) _100-n (mol%), n = 20 An analytical composition of Hf _3.9 Cr _35.1 O ₆₁ (atomic%) for the target and Hf _23.7 Cr ₁₂ O _64.3 (atomic%) of the target with n = 80 were obtained. These analytical compositions were almost equal to the reduced composition (atomic%) of the nominal composition (mol%). Therefore, when expressed by the formula (110) of (HfO ₂ ) _n (Cr ₂ O ₃ ) _100-n (mol%), the target composition in which n satisfies 20 ≦ n ≦ 80 is Hf _J Cr _K O _{100 It} can be seen that J and K satisfy 3 ≦ J ≦ 24, 11 ≦ K ≦ 36, and 34 ≦ J + K ≦ 40 when expressed by the formula (10) of _-JK (atomic%).

ではなく、元素基準の式（１）：

で得られた。誘電体層（Ｈｆ−Ｃｒ−Ｏ系材料層）の分析組成を表１に示す。 Further, an Hf—Cr—O-based material layer is formed as a dielectric layer by a sputtering method using a sputtering target having the above two kinds of nominal compositions (mol%), and this dielectric layer is formed by an X-ray microanalyzer method. The composition was analyzed. As a result, the analytical composition of the dielectric layer is calculated based on the oxide-based formula (11):

Instead of elemental formula (1):

Was obtained. Table 1 shows the analytical composition of the dielectric layer (Hf-Cr-O-based material layer).

  In this test, as for the dielectric layer, a sputtering target (diameter 100 mm, thickness 6 mm) having a nominal composition shown in Table 1 was attached to a general film forming apparatus (sputtering apparatus), and Ar gas ( In a 100%) atmosphere, sputtering was performed with a power of 500 W using a high-frequency power supply to form a film with a thickness of 500 nm on a Si substrate.

The analytical composition of a dielectric layer formed by a sputtering method using a sputtering target represented by the formula (110) of (HfO ₂ ) _n (Cr ₂ O ₃ ) _100-n (mol%) is the reduced composition of the sputtering target. And very close to the analytical composition.

  Therefore, Q and R in the analytical composition formula (1) of the dielectric layer are 3 ≦ Q ≦ 24, 11 ≦ R ≦ 36, and 34 in the same manner as J and K in the analytical composition (10) of the sputtering target. It is desirable to satisfy ≦ Q + R ≦ 40. However, the composition of the dielectric layer may differ depending on the structure of the film forming apparatus, the film forming conditions, the size of the sputtering target, the composition of the atmosphere gas, and the like, even if the same sputtering target is sputtered. As a result of considering such a possibility, Q and R in the above formula (1) preferably satisfy 0 <Q ≦ 30, 7 <R ≦ 37, and 20 ≦ Q + R ≦ 60, and more preferably 3 ≦ Q ≦ 24, 11 ≦ R ≦ 36, 34 ≦ Q + R ≦ 40.

Further, it is generally considered that Hf and Cr detected by the analysis of the dielectric layer are stably present in the dielectric layer in the form of HfO ₂ and Cr ₂ O ₃ , respectively. Therefore, when the content of Hf and Cr detected by the analysis of the sputtering target is substantially equal to the content of Hf and Cr detected by the analysis of the dielectric layer as in this test, the nominal composition (mol %) Is considered to be the same as the composition (mol%) of the dielectric layer formed by a sputtering method using the sputtering target. As a result, a dielectric layer (Hf-Cr) formed by a sputtering method using a sputtering target of (HfO ₂ ) _n (Cr ₂ O ₃ ) _100-n (mol%) whose nominal composition is expressed by the formula (110) The —O-based material layer) is represented by the formula (11) of (HfO ₂ ) _N (Cr ₂ O ₃ ) _{100 -N} (mol%), where _N in the formula (11) is n in the formula (110). It is considered to be substantially the same.

で公称組成が表記され、ｘおよびｙの値の異なる（ｘ＝２０且つｙ＝６０；ｘ＝７０且つｙ＝２０；およびｘ＝３０且つｙ＝３０）３種類のスパッタリングターゲットを粉末状にし、試験１と同様に分析した。この結果、スパッタリングターゲットの分析組成が、酸化物基準の式（２１０）ではなく、元素基準の式（２０）：

で得られた。得られたターゲットの分析組成を表２に示す。また、試験１と同じく、スパッタリングターゲットの公称組成に基づいて計算した換算組成（原子％）を表２に付記する。尚、表２に示す換算組成において、全ての元素の割合の合計は必ずしも１００％になっていないが、換算組成は適宜四捨五入して計算して得たためである。 (Test 2)
In this test, the composition of a sputtering target composed of a HfO ₂ —Cr ₂ O ₃ —SiO ₂ material, which is one of the Hf—Cr—O-based materials, was analyzed. And examined the differences. More specifically, equation (210):

The nominal composition is written in, and three types of sputtering targets having different values of x and y (x = 20 and y = 60; x = 70 and y = 20; and x = 30 and y = 30) are powdered, Analysis was performed as in Test 1. As a result, the analysis composition of the sputtering target is not the oxide-based formula (210), but the element-based formula (20):

Was obtained. Table 2 shows the analysis composition of the obtained target. Further, as in Test 1, the reduced composition (atomic%) calculated based on the nominal composition of the sputtering target is additionally shown in Table 2. In addition, in the converted compositions shown in Table 2, the sum of the proportions of all the elements is not always 100%, but the converted compositions are obtained by appropriately rounding and calculating.

As shown in Table 2, the result of analyzing the powder of the sputtering target whose nominal composition is expressed by the formula (210) of (HfO ₂ ) _x (Cr ₂ O ₃ ) _y (SiO ₂ ) _100-xy (mol%) , Hf _5.0 Cr _28.3 Si _5.1 O _61.6 (at.%) For a target with x = 20 and y = 60, Hf _20.9 Cr _12.0 Si _2.4 O _64.7 (at.%) For a target with x = 70 and y = 20, x = 30 An analytical composition of Hf _7.9 Cr _16.5 Si _11.3 O _64.3 (atomic%) was obtained for the target with y = 30. These analytical compositions were almost equal to the reduced composition (atomic%) of the nominal composition (mol%). Therefore, when expressed by the formula (210) of (HfO ₂ ) _x (Cr ₂ O ₃ ) _y (SiO ₂ ) _100-xy (mol%), x and y are 60 ≦ x + y ≦ 90, 20 ≦ x The target composition that satisfies ≦ 70 and 20 ≦ y ≦ 60 is represented by the formula (20) of Hf _G Cr _H Si _L O _100-GHL (at.%), Where G, H and L are 4 ≦ G ≦ 21, 11 ≦ H ≦ 30, 2 ≦ L ≦ 12, and 34 ≦ G + H + L ≦ 40.

ではなく、元素基準の式（２）：

で得られた。誘電体層（Ｈｆ−Ｃｒ−Ｏ系材料層）の分析組成を表２に示す。 Further, an Hf—Cr—O-based material layer was formed as a dielectric layer by a sputtering method using a sputtering target having the above-mentioned three types of nominal compositions (mol%). analyzed. As a result, the analytical composition of the dielectric layer is calculated based on the oxide-based formula (21):

Instead of elemental formula (2):

Was obtained. Table 2 shows the analytical composition of the dielectric layer (Hf-Cr-O-based material layer).

  In this test, the dielectric layer was formed with a thickness of 500 nm on a carbon (C) substrate by sputtering a sputtering target having a nominal composition shown in Table 2 under the same conditions as in Test 1.

(HfO ₂ ) _x (Cr ₂ O ₃ ) _y (SiO ₂ ) The analytical composition of a dielectric layer formed by a sputtering method using a sputtering target represented by the formula (210) of _100-xy (mol%) is as follows: As in the case of Test 1, both the reduced composition and the analyzed composition of the sputtering target were very close.

  Therefore, U, V, and T in the analytical composition (2) of the dielectric layer are 4 ≦ U ≦ 21 and 11 ≦ V, like G, H, and L in the analytical composition (20) of the sputtering target. ≤30, 2≤T≤12, and 34≤U + V + T≤40. However, as a result of considering the same possibility as in the case of Test 1, U, V and T in the above equation (2) are 0 <U ≦ 30, 7 <V ≦ 37, 0 <T ≦ 14, and 20 ≦ U + V + T ≤60, more preferably 4≤U≤21, 11≤V≤30, 2≤T≤12, and 34≤U + V + T≤40.

Also, it is considered that Hf, Cr and Si detected by the analysis of the dielectric layer are generally stably present in the dielectric layer in the form of HfO ₂ , Cr ₂ O ₃ and SiO ₂ , respectively. Can be Therefore, based on the same considerations as in Test 1, using a sputtering target whose nominal composition is represented by the formula (210) of (HfO ₂ ) _x (Cr ₂ O ₃ ) _y (SiO ₂ ) _100-xy (mol%) The dielectric layer (Hf—Cr—O-based material layer) formed by the sputtering method is represented by the formula (21) of (HfO ₂ ) _X (Cr ₂ O ₃ ) _Y (SiO ₂ ) _100-XY (mol%). X and Y in the equation (21) are considered to be substantially the same as x and y in the equation (210).

  According to the results of Tests 1 and 2, the reduced composition obtained from the nominal composition of the sputtering target was very close to the analysis composition, and the Hf—Cr—O-based material layer was formed under the conditions adopted by the present inventors. Since the analysis composition of the dielectric layer was close to that of the dielectric layer, the reduced composition (atomic%) of the sputtering target could be regarded as the composition (atomic%) of the dielectric layer formed by sputtering using the target, and the composition was substantially acceptable. . As long as the Hf—Cr—O-based material layer is formed under the conditions adopted by the present inventors, the nominal composition (mol%) of the sputtering target is substantially regarded as the composition (mol%) of the dielectric layer. No problem.

  Further, in Tests 1 and 2, the Hf-Cr-O-based material layer was tested, but the Hf-Cr-Zn-O-based material layer, the Hf-Zr-Cr-O-based material layer, and the Hf-Zr-Cr-Zn- The same applies to the O-based material layer.

  Therefore, in the following examples, the composition of the sputtering target is represented by a nominal composition (mol%), and unless otherwise specified, the sputtering target and an Hf / Zr—Cr—O-based material formed by a sputtering method using the sputtering target. The composition (mol%) of the layer or the Hf / Zr-Cr-Zn-O-based material layer was considered to be the same. In the following examples, the compositions of the sputtering target and the Hf / Zr-Cr-O-based material layer and the Hf / Zr-Cr-Zn-O-based material layer are described only on a compound basis (mol%). Those skilled in the art will be able to easily obtain the element-based composition (atomic%) by conversion based on the compound-based composition (mol%).

(Example 1)
Example 1 has a structure similar to that of the information recording medium 25 described in Embodiment 1 with reference to FIG. 1 as a preliminary test until the present invention is completed. An information recording medium in which the second dielectric layer and the second dielectric layer were made of materials having the same composition as each other was manufactured by changing the material of these dielectric layers as shown in Table 3.

  Hereinafter, a method for manufacturing the information recording medium will be described. For ease of understanding, the same reference numerals as those in the information recording medium 25 in FIG. Similarly, the same numbers are used for the information recording media of the embodiments of the present invention as those of the corresponding components of the information recording media.)

  First, as the substrate 1, a guide groove having a depth of 56 nm and a track pitch (center-to-center distance between the groove surface and the land surface in a plane parallel to the main surface of the substrate) 0.615 μm is provided in advance on one surface, and has a diameter of 120 mm. A 0.6 mm thick circular polycarbonate substrate was prepared.

On this substrate 1, a first dielectric layer 2 of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) having a thickness of 150 nm and a recording layer of Ge ₂₇ Sn ₈ Sb ₁₂ Te ₅₃ (atomic%) 4 has a thickness of 9 nm, a second dielectric layer 6 of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) has a thickness of 50 nm, and a light absorption correction layer 7 of Ge ₈₀ Cr ₂₀ (atomic%). Was formed to a thickness of 40 nm, and a reflective layer 8 of Ag-Pd-Cu was formed to a thickness of 80 nm sequentially by a sputtering method as follows.

In the step of forming the first dielectric layer 2, a sputtering target (diameter 100 mm, thickness 6 mm) having a composition of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) is attached to the film forming apparatus, and power 400 W Then, a high-frequency sputtering was performed by introducing a mixed gas of Ar gas (97%) and O ₂ gas (3%). The pressure during sputtering was about 0.13 Pa.

In the step of forming the recording layer 4, a sputtering target (100 mm in diameter, thickness 100 mm) made of a Ge—Sn—Sb—Te-based material in which a part of Ge of a GeTe—Sb ₂ Te ₃ pseudo-binary composition is replaced with Sn. 6 mm) was attached to a film forming apparatus, and DC sputtering was performed at a power of 100 W by introducing a mixed gas of Ar gas (97%) and N ₂ gas (3%). The pressure during sputtering was about 0.13 Pa.

  The step of forming the second dielectric layer 6 was performed in the same manner as the step of forming the first dielectric layer 2 except that the layer thickness was changed. As a result, the first dielectric layer 2 and the second dielectric layer 6 have substantially the same composition.

In the step of forming the light absorption correction layer 7, a sputtering target (diameter 100 mm, thickness 6 mm) made of a material having a composition of Ge ₈₀ Cr ₂₀ (atomic%) is attached to the film forming apparatus, and a power of 300 W and an Ar gas (100%) was introduced to perform DC sputtering. The pressure during sputtering was about 0.4 Pa.

  In the step of forming the reflective layer 8, a sputtering target (100 mm in diameter, 6 mm in thickness) made of a material having a composition of Ag-Pd-Cu was attached to the film forming apparatus, and Ar gas (100%) was supplied at a power of 200 W. DC sputtering was carried out. The pressure during sputtering was about 0.4 Pa.

  As described above, the first dielectric layer 2, the recording layer 4, the second dielectric layer 6, the light absorption correction layer 7, and the reflection layer 8 were sequentially formed on the substrate 1 to form a laminate. Thereafter, an ultraviolet curable resin was applied on the reflective layer 8, and a circular polycarbonate substrate having a diameter of 120 mm and a thickness of 0.6 mm as the dummy substrate 10 was adhered onto the applied ultraviolet curable resin. Then, ultraviolet rays were irradiated from the side of the dummy substrate 10 to cure the resin. As a result, the adhesive layer 9 made of the cured resin was formed with a thickness of 30 μm, and at the same time, the dummy substrate 10 was bonded to the laminate via the adhesive layer 9.

  After bonding the dummy substrate 10, an initialization step was performed. In the initialization step, the recording layer 4 of the information recording medium 25 was crystallized almost entirely in an annular region having a radius of 22 to 60 mm using a semiconductor laser having a wavelength of 810 nm. Thus, the initialization process was completed, and the production of the information recording medium 25 of the sample number 1-1 was completed.

  Further, a sample number having the same configuration as the information recording medium 25 of sample number 1-1 except that the material of the first dielectric layer 2 and the second dielectric layer 6 is made of the material shown in Table 3 The information recording media 25 of 1-2 to 1-19 were produced. These information recording media 25 are the same as the information recording medium 25 of the sample number 1-1 described above, except that the steps of forming the first dielectric layer and the second dielectric layer are changed. Produced.

In order to manufacture the information recording media 25 of the sample numbers 1-2 to 1-19, in the step of forming the first dielectric layer 2 and the second dielectric layer 6, SiO ₂ , ZnS, (ZnSe) ₈₀ (SiO ₂ ) ₂₀ (mol%), ZnSe, (ZnO) ₈₀ (SiO ₂ ) ₂₀ (mol%), ZnO, Cr ₂ O ₃ , (Cr ₂ O ₃ ) ₅₀ (SiO ₂ ) ₅₀ (mol%), ZrO ₂ , ZrSiO ₄ , (ZrO ₂ ) ₈₀ (SiO ₂ ) ₂₀ (mol%), Ge ₉₀ Cr ₁₀ (atomic%), (Bi ₂ O ₃ ) ₈₀ (SiO ₂ ) ₂₀ (mol%), TeO ₂ , A sputtering target made of a material having a composition of (TeO ₂ ) ₈₀ (SiO ₂ ) ₂₀ (mol%), HfO ₂ , HfSiO ₄ , and (HfO ₂ ) ₈₀ (SiO ₂ ) ₂₀ (mol%). , Thickness 6 mm) .

The power is adjusted according to the melting point of the material used as the sputtering target, and specifically, 1 kW for sample number 1-2 and sample number 1-1 for sample numbers 1-3 to 1-7. Similarly, the power was set to 400 W, 500 W for sample numbers 1-8 to 1-12 and 1-17 to 1-19, 300 W for sample number 1-13, and 200 W for sample numbers 1-14 to 1-16. The pressure during sputtering was about 1.33 Pa for sample No. 1-13, but was about 0.13 Pa for other samples, similar to sample No. 1-1. The gas introduced into the film forming apparatus is a mixed gas of Ar gas (97%) and O ₂ gas (3%) as in sample number 1-1 for sample numbers 1-2 and 1-14 to 1-16. Ar gas (100%) was used for sample numbers 1-3 to 1-12 and 1-17 to 19, and Ar gas (60%) and N ₂ gas (40%) were used for sample number 1-13. ) Was used.

In the step of forming the first and second dielectric layers, in the case of the information recording medium of Sample No. 1-13, N ₂ in the mixed gas reacts with Ge and Cr sputtered from the sputtering target. A dielectric layer of Ge-Cr-N was formed. For other samples, it was believed that the deposited dielectric layer would have substantially the same composition as the sputtering target used.

  In addition, for comparison, a first interface between the first dielectric layer 102 and the recording layer 4 and between the second dielectric layer 106 and the recording layer 4 as shown in FIG. An information recording medium 31 having a conventional configuration including the layer 103 and the second interface layer 105 was manufactured. Each of the first interface layer 103 and the second interface layer 105 was a layer of Ge-Cr-N having a thickness of 5 nm.

The information recording medium 31 having the conventional configuration was manufactured under the same manufacturing conditions as the information recording medium of Sample No. 1-1 except that the first interface layer 103 and the second interface layer 105 were formed. In the step of forming the first interface layer 103, a sputtering target (100 mm in diameter, 6 mm in thickness) made of a material having a composition of Ge ₉₀ Cr ₁₀ (atomic%) is attached to the film forming apparatus, and a power of 300 W and an Ar gas (60%) and a mixed gas of N ₂ gas (40%) were introduced, and high-frequency sputtering was performed under a pressure of about 1.33 Pa. As a result, N ₂ in the mixed gas reacted with Ge and Cr sputtered from the sputtering target, and a Ge—Cr—N layer was formed as the first interface layer 103. The film forming step of the second interface layer 105 was also performed under the same conditions.

  With respect to the information recording medium 25 of the sample numbers 1-1 to 1-19 and the information recording medium 31 of the comparative example (conventional configuration) obtained as described above, the adhesion of the dielectric layer and the rewriting performance of the information recording medium are repeated. Was evaluated. As described later, the adhesiveness was evaluated by the presence or absence of peeling, and the rewriting performance was evaluated by the number of repetitions. Table 3 shows the results. Note that neither the information recording medium 25 of the sample numbers 1-1 to 1-19 nor the information recording medium 31 of the comparative example belongs to the scope of the present invention.

  The evaluation of the adhesion of the dielectric layer on the information recording medium 25 was performed based on the presence or absence of peeling under high temperature and high humidity conditions. More specifically, after the information recording medium 25 after the initialization step is left in a high-temperature and high-humidity bath at a temperature of 90 ° C. and a relative humidity of 80% for 100 hours, the space between the recording layer and the dielectric layer in contact therewith is more detailed. Was visually inspected using an optical microscope to determine whether at least one of the interface between the recording layer 4 and the first dielectric layer 2 and the interface between the recording layer 4 and the second dielectric layer 6 did not occur. . Of course, those without peeling have high evaluation of adhesion, and those with peeling have low evaluation of adhesion.

  The evaluation of the rewrite performance of the information recording medium 25 was performed using the number of repetitions as an index, and the number of repetitions was determined under the following conditions.

  In order to record information on the information recording medium 25, a spindle motor for rotating the information recording medium 25, an optical head including a semiconductor laser that emits a laser beam 12, and the laser beam 12 on the recording layer 4 of the information recording medium 25. An information recording system having a general configuration including an objective lens for focusing light was used. In the evaluation of the information recording medium 25, recording corresponding to a capacity of 4.7 GB was performed using a semiconductor laser having a wavelength of 660 nm and an objective lens having a numerical aperture of 0.6. The linear speed at which the information recording medium 25 was rotated was 8.2 m / sec. A time interval analyzer was used for measuring the jitter value when calculating the average jitter value described later.

  First, a peak power (Pp) and a bias power (Pb) were set according to the following procedure in order to determine measurement conditions for determining the number of repetitions. Using the above system, the laser beam 12 is irradiated to the information recording medium 25 while power-modulating between the peak power (mW) of the high power level and the bias power (mW) of the low power level, A random signal having a mark length of 0.42 μm (3 T) to 1.96 μm (14 T) was recorded ten times on the same groove surface of the recording layer 4 (by groove recording). Then, a jitter value between the front end and a jitter value between the rear end were measured, and an average value was obtained as an average value of these. When the bias power is fixed and the peak power is varied, the average jitter value is measured under various recording conditions, and when the peak power is gradually increased, the average jitter value of the random signal reaches 13%. The power 1.3 times the peak power of was temporarily determined as Pp1. Next, the peak power was fixed at Pp1, and the average jitter value was measured under various recording conditions in which the bias power was variously changed. When the average jitter value of the random signal became 13% or less, the upper limit value of the bias power was obtained. And the average of the lower limit was set to Pb. Then, the bias power was fixed to Pb, and the average jitter value was measured under various recording conditions in which the peak power was variously changed. When the peak power was gradually increased, the average jitter value of the random signal reached 13%. The power 1.3 times the peak power of was set as Pp. When recording was performed under the conditions of Pp and Pb set in this way, an average jitter value of 8 to 9% was obtained, for example, in 10 repetitive recordings. In consideration of the upper limit of the laser power of the system, it is desirable to satisfy Pp ≦ 14 mW and Pb ≦ 8 mW.

  In the present embodiment, the number of repetitions, which is an index of the rewrite performance, was determined based on the average jitter value. The laser light is irradiated onto the information recording medium 25 while power-modulating the laser light with Pp and Pb set as described above, and a random signal having a mark length of 0.42 μm (3T) to 1.96 μm (14T) is converted to ( After continuous and repeated recording on the same groove surface a predetermined number of times (by groove recording), the average jitter value was measured. The average jitter value is measured when the number of repetitions is 1, 2, 3, 5, 10, 100, 200, and 500. When the number of repetitions is in the range of 1,000 to 10,000, it is measured every 1000 times. Was measured every 10000 times in the range of 20,000 to 100,000 times. When the average jitter value reached 13%, it was judged as the limit of repeated rewriting, and the repetition rewriting performance was evaluated based on the number of repetitions. Of course, the larger the number of repetitions, the higher the rewrite performance. When the information recording medium is used as an external memory of a computer, the number of repetitions is preferably 100,000 or more, and if it is used for an image / audio recorder, it is preferably 10,000 or more.

  As shown in Table 3, among the information recording media of sample numbers 1-1 to 1-12, an information recording medium without peeling (high adhesion) (that is, sample numbers 1-1 and 1-3 to 1--1) was used. In the case of 9), the number of repetitions is less than 100000 times (repetition rewriting performance is low), but the information recording medium with peeling (low adhesion) (that is, sample numbers 1-2, 1-10) 1-12 and 1-17 to 1-19), the tendency was observed that the number of repetitions exceeded 100,000 (high repetition rewriting performance).

  Further, with respect to the information recording media of sample numbers 1-13 and 1-14, sufficient recording marks could not be formed at a peak power of 14 mW or less, and thus the recording sensitivity was low. For this reason, it was expected that the thermal conductivity of the material of the dielectric layer in these samples was higher than those of the other samples.

  Further, the information recording media of sample numbers 1-15 and 1-16 could not be rewritten, and the material of the dielectric layer melted during recording and was mixed with the recording layer. This is considered to be because the melting point of the material of the dielectric layer in these samples is lower than those of other materials.

  On the other hand, in the information recording medium of the comparative example having the conventional configuration (which includes the interface layer), there was no peeling, the number of repetitions was 100,000 or more, and both the adhesion and the rewriting performance were high. .

According to the results of the above preliminary tests, oxide, nitride, selenide, sulfide, or a mixture of any of these and SiO ₂ was used as the material of the dielectric layer in contact with the recording layer. None of the information recording media of Sample Nos. 1-1 to 1-19 simultaneously satisfied high adhesion and high repetitive rewriting performance. However, what has been clarified in the present example is that information recording media (sample numbers 1-10 to 1-12 and 1-17 to 1- 1) using a material containing HfO ₂ or ZrO ₂ as a material for the dielectric layer were used. 19) is excellent in repetitive rewriting performance, and uses an information recording medium (sample numbers 1-1 and 1-3 to 1-9) using a material containing ZnS, ZnO, ZnSe, and Cr ₂ O ₃ as a material of the dielectric layer. ) Was excellent in adhesion to the recording layer. In particular, the Cr ₂ O ₃ consisting essentially of material information recording medium using the material for the dielectric layers (Sample No. 1-8), since the number of rewrites 10000 times for repeated rewriting performance is obtained, and HfO ₂ By using a mixture with Cr ₂ O ₃ as the dielectric layer material, it was expected that high adhesion and high repetitive rewriting performance could be simultaneously achieved.

(Example 2)
In Example 2, in order to simultaneously achieve high adhesiveness and high repetitive rewriting performance, information recording using a mixture of a material having excellent adhesiveness and a material having excellent repetitive rewriting performance as a material for the dielectric layer was performed. A medium was prepared. Specifically, a mixture of two of the oxide, selenide, and sulfide of Example 1 (see Table 4) was used as the material of the dielectric layer. In this embodiment, as in the first embodiment, the information recording medium 25 in which the first dielectric layer and the second dielectric layer have the same composition as each other is shown in Table 4. As shown in FIG.

  The information recording medium according to the present embodiment has the same configuration as the information recording medium 25 according to the first embodiment except that the materials of the first and second dielectric layers are made of the materials shown in Table 4. The second dielectric layer was manufactured in the same manner as above except that the film forming process was changed. In order to manufacture the information recording media of Sample Nos. 2-1 to 2-8, in the step of forming the first dielectric layer and the second dielectric layer, a material having a predetermined composition shown in Table 4 is used. A sputtering target (diameter 100 mm, thickness 6 mm) was used. Further, in the step of forming the first dielectric layer and the second dielectric layer, the power was set to 500 W for the sample numbers 2-1 and 2-2 and 400 W for the sample numbers 2-3 to 2-8. The pressure was about 0.13 Pa for each sample, and Ar gas (100%) was used for each sample as the gas introduced into the film forming apparatus.

  The dielectric layer formed by the sputtering method was considered to have substantially the same composition as the sputtering target used. The same applies to the embodiments described below unless otherwise specified.

  With respect to the information recording media of Sample Nos. 2-1 to 2-8 obtained as described above, the adhesion of the dielectric layer and the repetitive rewriting performance of the information recording medium were evaluated in the same manner as in Example 1. Table 4 shows the results. Incidentally, among the information recording media of sample numbers 2-1 to 2-8, the information recording media of sample numbers 2-1 and 2-2 belong to the scope of the present invention.

As shown in Table 4, peeling did not occur in all of the information recording media of sample numbers 2-1 to 2-8, and thus the adhesion was improved. Among these information recording media, those using HfO ₂ —Cr ₂ O ₃ -based material as the material of the dielectric layer (sample numbers 2-1 and 2-2) have a large number of repetitions and extremely excellent repetitive rewriting performance. I was According to this result, when a layer (Hf—Cr—O-based material layer) made of a mixture of HfO ₂ and Cr ₂ O ₃ is used as the dielectric layer in contact with the recording layer, the recording layer and the dielectric In the information recording medium having the configuration in which the interface layer is not provided between the layers, high adhesion and high repetitive rewriting performance were simultaneously achieved.

In addition, in order to quickly diffuse heat in the thickness direction from the recording layer to the reflective layer, the dielectric layer preferably has a low thermal conductivity. In Example 2, the information recording medium (sample numbers 2-1 and 2-2) using the HfO ₂ —Cr ₂ O ₃ material as the dielectric layer material was extremely excellent in the rewriting performance. Comparing the peak power (Pp) of these information recording media, the information recording medium of sample number 2-1 has a peak power of 13 mW, the information recording medium of sample number 2-2 has a peak power of 13.5 mW, and contains Cr ₂ O ₃ . The higher the ratio (on an oxide basis), the higher the Pp. On the other hand, in an information recording medium (sample numbers 2-3 to 2-8) in which HfO ₂ -ZnS, HfO ₂ -ZnO, or HfO ₂ -ZnSe-based material is used as the material of the dielectric layer, the repetitive rewriting performance is low. Although inferior, Pp was in the range of 11 mW to 12 mW, and the recording sensitivity was high. Therefore, these materials were more thermally conductive than the HfO ₂ —Cr ₂ O ₃ material. The rate was expected to be low. From these results, the dielectric layer material was obtained by mixing a material obtained by mixing HfO ₂ —Cr ₂ O ₃ with any one of HfO ₂ —ZnS, HfO ₂ —ZnO, and HfO ₂ —ZnSe. In addition to achieving high adhesiveness and high repetitive rewriting performance at the same time, high recording sensitivity could be expected. Further, in order to suppress the crystal growth of ZnS and ZnSe having strong crystallinity, it was studied to mix amorphous SiO ₂ with them.

(Example 3)
In Example 3, in order to realize an information recording medium having high recording sensitivity, a material of HfO ₂ —Cr ₂ O ₃ and a material of HfO ₂ —ZnS, HfO ₂ —ZnO, and HfO ₂ —ZnSe were used. For the purpose of suppressing the crystal growth of ZnS and ZnSe having high crystallinity by mixing with any of the materials, an information recording medium in which a material further mixed with amorphous SiO ₂ is used as a material of the dielectric layer. Produced. Further, an information recording medium using a mixture of HfO ₂ —Cr ₂ O ₃ material and SiO ₂ as a material of the dielectric layer was also manufactured. Also in this embodiment, as in the first embodiment, the information recording medium 25 in which the first dielectric layer and the second dielectric layer have the same composition as each other is shown in Table 5. As shown in FIG.

  The information recording medium of the present embodiment is also the same as the information recording medium 25 of the first embodiment, except that the materials of the first and second dielectric layers are the materials shown in Table 5 as in the second embodiment. It was constructed under the same conditions except that the film formation process of the first and second dielectric layers was changed. In order to manufacture the information recording media of sample numbers 3-1 to 3-9, the first and second dielectric layers are formed of a material having a predetermined composition shown in Table 5 in the film forming process of the first and second dielectric layers. A sputtering target (diameter 100 mm, thickness 6 mm) was used. Further, in the film forming process of the first dielectric layer and the second dielectric layer, the power was 500 W for sample numbers 3-1 and 3-2 and 3-6, and the sample numbers 3-3 to 3-5. And 3-7 to 3-9, 400 W, the pressure was about 0.13 Pa for each sample, and the gas introduced into the film forming apparatus was Ar gas (100%) for each sample.

  With respect to the information recording media of Sample Nos. 3-1 to 3-9 obtained as described above, the adhesion of the dielectric layer and the rewriting performance of the information recording medium were evaluated in the same manner as in Example 1. Table 5 shows these results together with the peak power (Pp) obtained at the time of evaluation of the repetitive rewriting performance. For comparison, Table 5 also shows the results of the same evaluation performed on the information recording medium 31 of the conventional configuration shown in FIG. 10 manufactured in Example 1 (the same applies to Tables 6 to 10 relating to Examples described later). . All the information recording media of sample numbers 3-1 to 3-9 belong to the scope of the present invention.

As shown in Table 5, in the information recording media of Sample Nos. 3-1 and 3-2, there was no peeling and the number of repetitions was maintained at 100,000 or more, but the HfO ₂ —Cr ₂ O ₃ -based material was converted to a dielectric material. While the Pp of the information recording medium of Sample No. 3-1 used for the material of the body layer was 13.2 mW, a material obtained by mixing HfO ₂ —Cr ₂ O ₃ -based material with SiO ₂ was used for the dielectric layer. In the information recording medium of Sample No. 3-2 used for the material, Pp was able to be reduced to 12.6 mW. Sample Nos. 3-3 to 3-3 in which a material in which 10 mol% of Cr ₂ O ₃ contained in the material of the dielectric layer of Sample No. 3-2 was replaced with ZnS, ZnSe, or ZnO was used as the material of the dielectric layer. In the information recording medium of −5, Pp could be further reduced, and in the information recording medium of sample number 3-3, a low Pp of 11.6 mW was obtained.

In the information recording media of Sample Nos. 3-6 to 3-9, the material of the dielectric layer was a HfSiO ₄ material containing HfO ₂ and SiO ₂ in substantially equal proportions. Since the composition of the dielectric layer material is expressed on an oxide basis in mol% units, for example, (HfO ₂ ) ₃₅ (Cr ₂ O ₃ ) ₃₀ (SiO ₂ ) ₃₅ (mol%) becomes (HfSiO ₄ ) ₃₅ (Cr ₂ O ₃ ) ₃₀ (molar ratio), which is converted into 100% (HfSiO ₄ ) ₅₄ (Cr ₂ O ₃ ) ₄₆ (mol%) (the material of the dielectric layer of sample No. 3-6). Become. With such information recording media of sample numbers 3-6 to 3-9, a low Pp of 11 to 12 mW was obtained. In particular, in the information recording medium of Sample No. 3-7 in which a material in which a part of Cr ₂ O ₃ was replaced by ZnS was used as the material of the dielectric layer, the adhesion was the same as that of the information recording medium 31 having the conventional configuration of the comparative example. (Peeling), rewriting performance (number of repetitions), and Pp were obtained. In addition, the measured Rc value (in the flat portion having no unevenness) of the information recording media of Sample Nos. 3-1 to 3-9 manufactured in this example is 15% to 17%, and the Ra measured value is 2% or less. Met.

As described above, as the dielectric layer in contact with the recording layer, a layer made of a HfO ₂ —Cr ₂ O ₃ system or a HfO ₂ —Cr ₂ O ₃ —SiO ₂ system material (Hf—Cr—O system material layer) If) with, or HfO ₂ -Cr ₂ O ₃ when used in -SiO ₂ ZnS, a layer made of a material based mixed with ZnSe or ZnO with (Hf-Cr-ZnO-based material layer), the In the information recording medium 25 shown in FIG. 1 having the configuration in which the first and second interface layers are not provided (therefore, the number of layers is smaller than that of the conventional configuration), the conventional configuration shown in FIG. Performance equivalent to that of the information recording medium 31 was obtained.

  In the present embodiment, the materials of the same composition are used for the materials of the first and second dielectric layers. However, the materials are selected from Hf / Zr-Cr-O-based materials and Hf / Zr-Cr-O-based materials. Alternatively, layers having different compositions from each other can be used for the first and second dielectric layers. In that case, the same good performance as the result of this example was obtained.

(Example 4-1)
In Example 4-1, as shown in Table 6-1, the HfO ₂ —Cr ₂ O ₃ system material was examined for the composition range suitable for use in the dielectric layer. The information recording medium was manufactured by varying the content (mol%) of HfO ₂ and Cr ₂ O ₃ in the above materials. The information recording medium of this example has a structure similar to that of the information recording medium 27 described in Embodiment 3 with reference to FIG. 3, and therefore, the first dielectric layer and the second dielectric layer are different. It was made of a material having a composition and provided with a first interface layer between the first dielectric layer and the recording layer.

The information recording medium 27 of this embodiment was manufactured as follows. First, a substrate 1 similar to that of Example 1 was prepared, and a first dielectric layer 102 of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) was formed on this substrate 1 to a thickness of 150 nm by Ge. the first interface layer 103 of -cr-N with a thickness of 5 nm, a Ge ₂₇ Sn ₈ Sb ₁₂ Te ₅₃ recording layer 4 (atomic%) in the 9nm thick, the composition shown in Table 6-1 The second dielectric layer 6 has a thickness of 50 nm, the Ge ₈₀ Cr ₂₀ (atomic%) light absorption correction layer 7 has a thickness of 40 nm, and the Ag—Pd—Cu reflection layer 8 has a thickness of 80 nm. Films were sequentially formed by a sputtering method. Here, each material of the first dielectric layer 102 and the first interface layer 103 is the same as that of the conventional information recording medium 31 described above with reference to FIG.

  The information recording medium 27 of the present embodiment is different from the information recording medium 27 in that a film forming step of the first interface layer 103 is added between the film forming step of the first dielectric layer 102 and the film forming step of the recording layer 4. The information recording medium of Example 1 was manufactured in the same manner as in the case of the information recording medium of Sample No. 1-1, except that the step of forming the dielectric layer 6 was changed. The step of forming the first interface layer 103 was performed in the same manner as the step of forming the first interface layer in the method of manufacturing the conventional information recording medium 31 of the comparative example described above in Example 1. . In addition, the film formation step of the second dielectric layer 6 includes a sputtering target (having a diameter of 100 mm, a predetermined composition shown in Table 6-1) for manufacturing the information recording media of Sample Nos. 4-1 to 4-11. The thickness of each sample was set to 6 mm, and for each sample, the gas introduced into the film forming apparatus was Ar gas (100%), the power was 500 W, and the pressure was about 0.13 Pa. The step of forming the first dielectric layer 102 includes the step of forming the first dielectric layer 2 in the method of manufacturing the information recording medium 25 of the sample number 1-1 described in the first embodiment. This is the same as the step of forming the first dielectric layer 102 in the method of manufacturing the information recording medium 31 having the conventional configuration.

  With respect to the information recording media 27 of the sample numbers 4-1 to 4-11 obtained as described above, the adhesion of the dielectric layer and the repetitive rewriting performance of the information recording media were almost the same as those described in the first embodiment. Although evaluation was performed in the same manner, in the present example, the evaluation of adhesion was performed by checking whether or not separation occurred between the recording layer 4 and the second dielectric layer 6 in contact with the recording layer. These results are shown in Table 6-1 together with the peak power (Pp) obtained in the evaluation of the rewrite performance. Incidentally, among the information recording media of sample numbers 4-1 to 4-11, the information recording media of sample numbers 4-3 to 4-9 belong to the scope of the present invention.

As shown in Table 6-1, peeling did not occur in the information recording media of Sample Nos. 4-3 to 4-11 in which the material of the second dielectric layer contained HfO ₂ at a ratio of 80 mol% or less. Further, in the information recording media of Sample Nos. 4-1 to 4-9 in which the material of the second dielectric layer contains HfO ₂ at a rate of 20 mol% or more, the number of repetitions is 100,000 or more, and Pp ≦ 14.0 mW. Therefore, with the information recording media of sample numbers 4-3 to 4-9, high adhesion and high repetitive rewriting performance were obtained, and low peak power was obtained. From the results of this example, it was confirmed that the material of the dielectric layer is preferably a material having a composition range of ₂₀ to 80 mol% of HfO ₂ in the case of HfO ₂ —Cr ₂ O ₃ .

(Example 4-2)
In Example 4-2, among the HfO ₂ —Cr ₂ O ₃ -based materials used in Example 4-1 above, three materials (sample numbers 4-3, 4-6, and 4-9) were subjected to HfO 2 instead of a part of the ₂ prepared material that contains ZrO _2, they were compared with those of the material and the HfO ₂ -Cr ₂ O ₃ based material. The contents (mol%) of HfO ₂ and ZrO ₂ were changed as shown in Table 6-2. The information recording medium of this example has the same structure as the information recording medium of Example 4-1. In the film forming process of the second dielectric layer, sample numbers 4-3a to 4c and 4-6a to c And the information recording media 4-9a to 4-9c were prepared under the same conditions as in Example 4-1 except that sputtering targets having a predetermined composition shown in Table 6-2 were used. At this time, the combined content of HfO ₂ and ZrO ₂ (that is, the content of the oxide MO ₂ of the first metal component) is 20 mol% in the sample numbers 4-3a to 4c, and is 4mol in the sample numbers 4-3a to c. It became 50 mol%, and it became 20 mol% in 4-9a-c.

  For the information recording media of sample numbers 4-3a to c, 4-6a to c, and 4-9a to c obtained as described above, the adhesion of the dielectric layer and the The rewriting performance of the information recording medium was evaluated. The results are shown in Table 6-2 together with the peak power (Pp) obtained in the evaluation of the rewrite performance.

As shown in Table 6-2, sample number 4-3a~c material for the second dielectric layer comprises both HfO ₂ and ZrO _2, 4-6A～c, and in 4-9A～c, As in the case of Sample Nos. 4-3, 4-6, and 4-9 of Example 4-1 including only Hf, no peeling occurred, high adhesion and high repetition performance were obtained, and low peaks were obtained. Power was obtained. From the results of this example, it is understood that both the HfO ₂ —Cr ₂ O ₃ -based material and the HfO ₂ —ZrO ₂ —Cr ₂ O ₃ -based material are suitable for constituting an information recording medium having good performance. Was confirmed.

(Example 5-1)
In Example 5-1, as shown in Table 7-1, a second composition of HfO ₂ —Cr ₂ O ₃ —SiO ₂ was used in order to investigate a composition range suitable for use in the dielectric layer. The information recording medium was manufactured by changing the content (mol%) of HfO ₂ , Cr ₂ O ₃ and SiO ₂ in the material of the dielectric layer in various ways. The information recording medium of the present embodiment has the same structure as the information recording medium of the embodiment 4-1. Was prepared under the same conditions as in Example 4-1 except that sputtering targets having a predetermined composition shown in Table 7-1 were used. At this time, from the results of Example 4-1, the content of SiO ₂ was changed in a range where the content of HfO ₂ was 20 mol% or more and the content of Cr ₂ O ₃ was 20 mol% or more.

  For the information recording media of Sample Nos. 5-1 to 5-12 obtained as described above, the adhesion of the dielectric layer and the rewriting performance of the information recording medium were evaluated in the same manner as in Example 4-1. These results are shown in Table 7-1 together with the peak power (Pp) obtained in the evaluation of the rewrite performance. Among the information recording media of sample numbers 5-1 to 5-12, the information recording media of sample numbers 5-1 to 5-4 and 5-7 to 5-12 belong to the scope of the present invention.

As shown in Table 7-1, information on sample numbers 5-1 to 5-4 and 5-7 to 5-12 in which the material of the second dielectric layer contains SiO ₂ at a ratio of 10 mol% or more and 40 mol% or less. In the recording medium, peeling did not occur, high adhesiveness and high repetitive rewriting performance were obtained, and low peak power was obtained. From the results of this example, the HfO ₂ —Cr ₂ O ₃ —SiO ₂ system contains ₂₀ to 70 mol% of HfO ₂ , ₂₀ to 60 mol% of Cr ₂ O ₃ , and SiO ₂ in the dielectric layer material. It was confirmed that a material having a composition range of 10 to 40 mol% is preferable.

(Example 5-2)
In Example 5-2, among the HfO ₂ —Cr ₂ O ₃ —SiO ₂ based materials used in Example 5-1 above, four materials (sample numbers 5-1 5-2, and 5-3) were used. Regarding 5-4), materials containing ZrO ₂ instead of part of HfO ₂ were prepared, and those materials were compared with HfO ₂ —Cr ₂ O ₃ —SiO ₂ -based materials. The contents (mol%) of HfO ₂ and ZrO ₂ were changed as shown in Table 7-2. The information recording medium of this embodiment has the same structure as that of the information recording medium of Embodiment 4-1. In the step of forming the second dielectric layer, sample numbers 5-1a and b, 5-2a and b Same as Example 4-1 except that sputtering targets having predetermined compositions shown in Table 7-2 were used for producing the information recording media of 5-3a and b and 5-4a and b, respectively. It was prepared under the following conditions. At this time, the combined content of HfO ₂ and ZrO ₂ (that is, the content of the oxide MO ₂ of the first metal component) is 70 mol% in the sample numbers 5-1a and b, and is 5-2a and b. 60 mol%, and 50 mol% for 5-3a and b, and 40 mol% for 5-4a and b.

  About the information recording media of sample numbers 5-1a and b, 5-2a and b, 5-3a and b, and 5-4a and b obtained as described above, in the same manner as in Example 4-1, The adhesion of the dielectric layer and the rewriting performance of the information recording medium were evaluated. These results are shown in Table 7-2 together with the peak power (Pp) obtained in the evaluation of the rewrite performance.

As shown in Table 7-2, sample numbers 5-1a and b, 5-2a and b, 5-3a and b in which the material of the second dielectric layer contains both HfO ₂ and ZrO ₂ , and 5- In 4a and 4b, similarly to the sample numbers 5-1 to 4 of Example 5-1 including only Hf, high repetition performance was obtained and low peak power was obtained. No peeling occurred in any of the samples, and the adhesion of the dielectric layer was high. From the results of this example, it can be seen that both the HfO ₂ —Cr ₂ O ₃ —SiO ₂ material and the HfO ₂ —ZrO ₂ —Cr ₂ O ₃ —SiO ₂ material constitute an information recording medium having good performance. It was confirmed that the material was suitable to be used.

(Example 6)
In Example 6, in order to investigate the composition range of HfSiO ₄ —Cr ₂ O ₃ based material containing HfO ₂ and SiO ₂ in substantially equal proportions and suitable for use in the dielectric layer, the second dielectric material was used. As shown in Table 8, the information recording medium was manufactured by changing the content (mol%) of HfSiO ₄ and Cr ₂ O _{3 as} the material of the layer. The information recording medium of this embodiment has the same structure as that of the information recording medium of Embodiment 4-1 as in Embodiment 5-1. The manufacturing method is the same as that of Example 5-1 and the description is omitted. At this time, the content of Cr ₂ O ₃ was changed in a range where the content of HfO ₂ and SiO ₂ was in the range of 20 mol% to 50 mol% (accordingly, the composition ratio of HfSiO ₄ was in the range of 25 mol% to 100 mol%). .

In Table 8, the information recording media of sample numbers 5-4, 5-9, and 5-12 correspond to the information recording media of Example 5-1 described above. Regarding the material of the second dielectric layer of the information recording media of sample numbers 5-4, 5-9 and 5-12 described in Table 7-1, (HfO ₂ ) ₄₀ (Cr ₂ O ₃ ) ₂₀ (SiO ₂ ) ₄₀ (mol%) is (HfSiO ₄ ) ₆₇ (Cr ₂ O ₃ ) ₃₃ (mol%), and (HfO ₂ ) ₃₀ (Cr ₂ O ₃ ) ₄₀ (SiO ₂ ) ₃₀ (mol%) is (HfSiO ₄ ). ) ₄₃ (Cr ₂ O ₃ ) ₅₇ (mol%) and (HfO ₂ ) ₂₀ (Cr ₂ O ₃ ) ₆₀ (SiO ₂ ) ₂₀ (mol%) are (HfSiO ₄ ) ₂₅ (Cr ₂ O ₃ ) ₇₅ (mol%). mol%).

  For the information recording media of Sample Nos. 5-4, 5-9, 5-12 and 6-1 to 6-4 obtained as described above, the adhesion of the dielectric layer was determined in the same manner as in Example 4-1. And the rewriting performance of the information recording medium was evaluated. Table 8 shows these results together with the peak power (Pp) obtained at the time of the evaluation of the rewrite performance. Among the information recording media of sample numbers 5-4, 5-9, 5-12 and 6-1 to 6-4, sample numbers 5-4, 5-9, 5-12, 6-3, and 6 -4 information recording medium belongs to the scope of the present invention.

As shown in Table 8, excluding the information recording media of Sample Nos. 6-1 and 6-2, no peeling occurred, high adhesion and high repetitive rewriting performance were obtained, and low peak power was obtained. . From the results of this example, it was confirmed that, as the material of the dielectric layer, in the case of the HfSiO ₄ —Cr ₂ O ₃ system, a material having a composition range including HfSiO ₄ at 25 to 67 mol% is preferable.

(Example 7)
In Example 7, in order to investigate a composition range suitable for use in the dielectric layer with respect to the HfO ₂ —Cr ₂ O ₃ —ZnS—SiO ₂ system material, the material of the second dielectric layer was set in Table 9 As shown in Table ₂ , information recording media were manufactured by varying the contents (mol%) of HfO ₂ , Cr ₂ O ₃ , ZnS and SiO ₂ . The information recording medium of this embodiment has the same structure as that of the information recording medium of Embodiment 4-1 as in Embodiment 5-1. The manufacturing method is the same as that in Example 5-1 except that the power was set to 400 W in the film forming process of the second dielectric layer, and thus the description is omitted. In this case, from the results of Examples 4-1, the content of HfO ₂ is 20 mol% or more, and the content of Cr ₂ O ₃ is in a range of more than 20 mol%, changing the content of ZnS and SiO _2.

  For the information recording media of Sample Nos. 7-1 to 7-16 obtained as described above, the adhesion of the dielectric layer and the repetitive rewriting performance of the information recording medium were evaluated in the same manner as in Example 4-1. Table 9 shows these results together with the peak power (Pp) obtained at the time of evaluation of the repetitive rewriting performance. Incidentally, among the information recording media of sample numbers 7-1 to 7-16, the information recording media of sample numbers 7-2 to 7-4 and 7-6 to 7-16 belong to the scope of the present invention.

As shown in Table 9, in the information recording medium of Sample No. 7-1 in which the material of the second dielectric layer contained ZnS at a ratio of 50 mol%, the number of repetitions was 1,000. Further, in the information recording medium of Sample No. 7-5 in which the material of the second dielectric layer contained SiO ₂ at a ratio of 50 mol%, peeling occurred. In the information recording media of other sample numbers, no peeling occurred, high adhesion and high repetitive rewriting performance were obtained, and low peak power was obtained. Therefore, according to the results of this example, the material of the dielectric layer is ₂₀ to 60 mol% of HfO ₂ and ₂₀ to 60 mol% of Cr ₂ O ₃ in the HfO ₂ —Cr ₂ O ₃ —ZnS—SiO ₂ system. It was confirmed that a material having a composition range including ZnS at 10 to 40 mol% and SiO ₂ at 10 to 40 mol% is preferable.

(Example 8)
In Example 8, in order to investigate the composition range of HfO ₂ —Cr ₂ O ₃ —ZnSe—SiO ₂ based material suitable for use in the dielectric layer, HfO ₂ , Cr ₂ O ₃ , ZnSe and SiO ₂ An information recording medium using various materials having different contents (mol%) from the above for the dielectric layer was produced in the same manner as in Example 7. This material contains ZnSe in place of ZnS in the materials examined in Example 7. When the same evaluation as in Example 7 was performed, in the HfO ₂ —Cr ₂ O ₃ —ZnSe—SiO ₂ system, HfO ₂ was ₂₀ to 60 mol%, Cr ₂ O ₃ was 20 to 60 mol%, and ZnSe was 10%. It has been confirmed that a material having a composition range of from about 40 mol% to about 40 mol% and containing SiO ₂ from 10 to 40 mol% is preferable.

(Example 9)
In Example 9, in order to investigate the composition range of HfO ₂ —Cr ₂ O ₃ —ZnO—SiO ₂ based material suitable for use in the dielectric layer, HfO ₂ , Cr ₂ O ₃ , ZnO, SiO ₂ An information recording medium using various materials having different contents (mol%) from the above for the dielectric layer was produced in the same manner as in Example 7. This material contains ZnO instead of ZnS in the materials examined in Example 7. When the same evaluation as in Example 7 was performed, in the HfO ₂ —Cr ₂ O ₃ —ZnO—SiO ₂ system, HfO ₂ was ₂₀ to 60 mol%, Cr ₂ O ₃ was 20 to 60 mol%, and ZnO was 10 mol%. It was confirmed that a material having a composition range of ４０40 mol% and containing SiO ₂ at ４０10-40 mol% is preferable.

(Example 10)
In Example 10, the material of the second dielectric layer was set as shown in Table 10 in order to investigate the composition range suitable for use in the dielectric layer for the HfSiO ₄ —Cr ₂ O ₃ —ZnS-based material. The information recording medium was manufactured by changing the contents (mol%) of HfSiO ₄ , Cr ₂ O ₃ and ZnS variously. The information recording medium of this embodiment has the same structure as that of the information recording medium of Embodiment 4-1 as in Embodiment 5-1. The manufacturing method is the same as that in Example 5-1 except that the power was set to 400 W in the film forming process of the second dielectric layer, and thus the description is omitted. At this time, the ZnS content was changed in a range where the HfSiO ₄ content was 25 mol% or more and the Cr ₂ O ₃ content was 25 mol% or more.

  With respect to the information recording media of Sample Nos. 8-1 to 8-10 obtained as described above, the adhesion of the dielectric layer and the repetitive rewriting performance of the information recording medium were evaluated in the same manner as in Example 4-1. Table 10 shows these results together with the peak power (Pp) obtained at the time of evaluation of the rewrite performance. The information recording media of sample numbers 8-1 to 8-10 all belong to the scope of the present invention.

As shown in Table 10, in all the information recording media of Sample Nos. 8-1 to 8-10, peeling did not occur, high adhesiveness and high repetitive rewriting performance were obtained, and low peak power was obtained. . Therefore, according to the results of this example, the HfSiO ₄ —Cr ₂ O ₃ —ZnS-based material contains 25 to 54 mol% of HfSiO ₄ , 25 to 63 mol% of Cr ₂ O ₃ , and ZnS It is confirmed that a material having a composition range of 12 to 50 mol% is preferable.

(Example 11)
In Example 11, the content (molar) of HfSiO ₄ , Cr ₂ O _3, and ZnSe was investigated in order to investigate the composition range suitable for the dielectric layer for the HfSiO ₄ —Cr ₂ O ₃ —ZnSe-based material. %) Were prepared in the same manner as in Example 10 using various materials having different%) for the dielectric layer. This material contains ZnSe in place of ZnS in the materials examined in Example 10. When the same evaluation as in Example 10 was performed, in the case of the HfSiO ₄ —Cr ₂ O ₃ —ZnSe system, HfSiO ₄ was 25 to 54 mol%, Cr ₂ O ₃ was 25 to 63 mol%, and ZnSe was 12 to 50 mol%. It has been confirmed that a material having a composition range included in is preferable.

(Example 12)
In Example 12, the content (molar) of HfSiO ₄ , Cr ₂ O _3, and ZnO was determined in order to investigate the composition range suitable for use in the dielectric layer for the HfSiO ₄ —Cr ₂ O ₃ —ZnO-based material. %) Were prepared in the same manner as in Example 10 using various materials having different%) for the dielectric layer. This material contains ZnO instead of ZnS in the materials examined in Example 10. The same evaluation as in Example 10 was performed. As in Example 10, the HfSiO ₄ —Cr ₂ O ₃ —ZnO system contained 25 to 54 mol% of HfSiO ₄ and 25 to 63 mol% of Cr ₂ O _3. It was confirmed that a material having a composition range containing ZnO at 12 to 50 mol% is preferable.

(Example 13)
Example 13 has the same structure as the information recording medium 26 described in Embodiment 2 with reference to FIG. 2, and the first dielectric layer and the second dielectric layer have different compositions from each other. An information recording medium made of a material was manufactured.

  The information recording medium 26 of the present example was manufactured as follows. First, as the substrate 1, a guide groove having a depth of 56 nm and a track pitch (center-to-center distance between the groove surface and the land surface in a plane parallel to the main surface of the substrate) 0.615 μm is provided in advance on one surface, and has a diameter of 120 mm. A 0.6 mm thick circular polycarbonate substrate was prepared.

On this substrate 1, a first dielectric layer 2 of (HfSiO ₄ ) ₃₃ (Cr ₂ O ₃ ) ₄₀ (ZnS) ₂₇ (mol%) having a thickness of 150 nm and a Ge ₂₇ Sn ₈ Sb ₁₂ Te ₅₃ (Atomic%) The recording layer 4 has a thickness of 9 nm, the Ge—Cr—N second interface layer 105 has a thickness of 3 nm, and a second layer of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%). The dielectric layer 106 has a thickness of 50 nm, the Ge ₈₀ Cr ₂₀ (atomic%) light absorption correction layer 7 has a thickness of 40 nm, and the Ag-Pd-Cu reflection layer 8 has a thickness of 80 nm. Were sequentially formed. Here, each material of the second interface layer 105 and the second dielectric layer 106 is the same as that of the conventional information recording medium 31 described above with reference to FIG.

The information recording medium 26 of the present embodiment differs from the information recording medium 26 in that the step of forming the first dielectric layer 2 is changed and that the step of forming the recording layer 4 and the step of forming the second dielectric layer 106 are different. The information recording medium was manufactured in the same manner as in the case of the information recording medium of Sample No. 1-1 in Example 1 except that a film formation step of the interface layer 105 of No. 2 was added. In the step of forming the first dielectric layer 2, a sputtering target (diameter 100 mm, thickness 6 mm) having a composition of (HfSiO ₄ ) ₃₃ (Cr ₂ O ₃ ) ₄₀ (ZnS) ₂₇ (mol%) is formed. The apparatus was attached to an apparatus, and high-frequency sputtering was performed under a pressure of about 0.13 Pa by introducing Ar gas (100%) at a power of 400 W. The step of forming the second interface layer 105 is performed in the same manner as the step of forming the second interface layer 105 in the method of manufacturing the information recording medium 31 having the conventional configuration of the comparative example described in the first embodiment. did. Note that the step of forming the second dielectric layer 106 is the same as the step of forming the second dielectric layer 6 in the method of manufacturing the information recording medium 25 of the sample number 1-1 described in the first embodiment. This is the same as the step of forming the second dielectric layer 106 in the method of manufacturing the information recording medium 31 having the conventional configuration.

  With respect to the information recording medium 26 of the sample number 9-1 obtained as described above, the adhesion of the dielectric layer and the rewriting performance of the information recording medium were evaluated in substantially the same manner as described in Example 1. However, in the present example, the evaluation of the adhesion was performed by checking whether or not peeling occurred between the recording layer 4 and the first dielectric layer 2 in contact with the recording layer. The evaluation of the repetitive rewriting performance was performed by performing land recording as well as groove recording (that is, by land-groove recording) and checking the number of repetitions for each of the groove recording and the land recording. Table 11 shows these results together with the peak power (Pp) and the bias power (Pb) obtained during the evaluation of the rewrite performance. In addition, for comparison, Table 11 also shows the results of similarly evaluating the information recording medium 31 of the conventional configuration shown in FIG.

As shown in Table 11, (HfSiO ₄ ) ₃₃ (Cr ₂ O ₃ ) ₄₀ (ZnS) ₂₇ (mol%) was used only for the material of the first dielectric layer 2 and formed on the substrate 1 by a sputtering method. In the information recording medium 26 of the sample number 9-1 of the present embodiment in which the number of layers to be changed (that is, the layers up to the reflective layer 8) is 6, the information recording of the conventional configuration of the comparative example in which the total number is 7 Adhesion, repetition times, peak power, and bias power equivalent to those of the medium 31 were obtained. In this embodiment, as the first dielectric layer 2, a layer (Hf—Cr—Zn) made of a material having a composition of (HfSiO ₄ ) ₃₃ (Cr ₂ O ₃ ) ₄₀ (ZnS) ₂₇ (mol%) is used. However, this composition is merely an example. In the case of the HfSiO ₄ —Cr ₂ O ₃ —ZnS-based material, the same composition as in the present example is applied over the composition range shown in Example 10. Good results were obtained. Furthermore, as the first dielectric layer 2, another Hf / Zr-Cr-O-based material layer or another Hf / Zr-Cr-Zn-O-based material layer may be used.

(Example 14)
In Example 14, an information recording medium having the same structure as the information recording medium 28 described in Embodiment 4 with reference to FIG. 4 was manufactured.

  The information recording medium 28 of this example was manufactured as follows. First, as the substrate 101, a guide groove with a depth of 21 nm and a track pitch (distance between the center of the groove surface and the center of the groove surface in a plane parallel to the main surface of the substrate) of 0.32 μm is provided in advance on one surface, and has a diameter of 120 mm. A polycarbonate substrate having a thickness of 1.1 mm was prepared.

On this substrate 101, a reflective layer 8 of Ag-Pd-Cu having a thickness of 80 nm and a second dielectric layer 6 of (HfSiO ₄ ) ₅₄ (Cr ₂ O ₃ ) ₄₆ (mol%) having a thickness of 16 nm were formed. The first dielectric layer 2 of (HfSiO ₄ ) ₅₄ (Cr ₂ O ₃ ) ₄₆ (mol%) is formed to have a thickness of 11 nm and a recording layer 4 of Ge _37.5 Sb ₁₁ Te _51.5 (at%). Films were sequentially formed at a thickness of 68 nm by a sputtering method.

  The step of forming the reflective layer 8 was performed under the same conditions as those in the method for manufacturing the information recording medium of Sample No. 1-1 in Example 1.

In the step of forming the second dielectric layer 6, a sputtering target (100 mm in diameter, 6 mm in thickness) made of a material having a composition of (HfSiO ₄ ) ₅₄ (Cr ₂ O ₃ ) ₄₆ (mol%) is formed. The apparatus was attached to the apparatus, and at a power of 500 W, Ar gas (100%) was introduced, and high-frequency sputtering was performed under a pressure of about 0.13 Pa.

In the step of forming a recording layer 4, a sputtering target (a diameter of 100 mm, a thickness 6mm) made of a Ge-Sb-Te-based material was attached to the film, at a power 100W, Ar gas (97%) and N ₂ gas (3%) of a mixed gas was introduced to perform DC sputtering. The pressure during sputtering was about 0.13 Pa.

  The step of forming the first dielectric layer 2 was performed in the same manner as the step of forming the second dielectric layer 6 except that the layer thickness was changed. As a result, the first dielectric layer 2 and the second dielectric layer 6 have substantially the same composition.

  As described above, the reflective layer 8, the second dielectric layer 6, the recording layer 4, and the first dielectric layer 2 are sequentially formed on the substrate 101 to form a laminated body. Was applied on the first dielectric layer 2, and a circular polycarbonate substrate having a diameter of 120 mm and a thickness of 90 μm as the dummy substrate 110 was adhered to the applied ultraviolet curable resin. Then, ultraviolet rays were irradiated from the side of the dummy substrate 110 to cure the resin. As a result, an adhesive layer 9 made of a cured resin was formed with a thickness of 10 μm, and the dummy substrate 110 was bonded to the laminate with the adhesive layer 9 interposed therebetween.

  After bonding the dummy substrates, an initialization step was performed. In the initialization step, the recording layer 4 of the information recording medium 28 was crystallized almost entirely in an annular region having a radius of 22 to 60 mm using a semiconductor laser having a wavelength of 670 nm. Thus, the initialization process was completed, and the manufacture of the information recording medium 28 of the sample number 10-1 was completed.

In addition, for comparison, a first interface layer of Ge—Cr—N is provided between the first dielectric layer 2 and the recording layer 4 and between the second dielectric layer 6 and the recording layer 4. 103 and a second interface layer 105, respectively, and instead of the first dielectric layer 2 and the second dielectric layer 6, a first (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) An information recording medium of a comparative example having a configuration similar to that of the information recording medium of the present example except that the information recording medium was provided with the dielectric layer 102 and the second dielectric layer 106 (not shown) was manufactured. Each of the first interface layer 103 and the second interface layer 105 was formed to a thickness of 5 nm.

  In the information recording medium of this comparative example, the step of forming the first interface layer 103 and the second interface layer 105 and the step of forming the first dielectric layer 102 and the second dielectric layer 106 include: The information recording medium was manufactured in the same manner as the method of manufacturing the information recording medium of the present example, except that the method was performed in the same manner as in the method of manufacturing the information recording medium 31 having the conventional configuration of the comparative example manufactured in Example 1.

  With respect to the information recording medium 28 of Sample No. 10-1 and the information recording medium (not shown) of the comparative example obtained as described above, the adhesion of the dielectric layer and the rewriting performance of the information recording medium were evaluated. Table 12 shows these results together with the peak power (Pp) obtained at the time of evaluation of the rewrite performance.

  In the present embodiment, the evaluation of the adhesion of the dielectric layer on the information recording medium 28 was performed under the same conditions as in the first embodiment. On the other hand, the evaluation of the repetitive rewriting performance of the information recording medium 28 was performed in the same manner as in the first embodiment using the number of repetitions as an index, but under different conditions from the first embodiment.

  When evaluating the repetitive rewriting performance of the information recording medium 28, using an information recording system having the same configuration as that of the first embodiment, using a semiconductor laser having a wavelength of 405 nm and an objective lens having a numerical aperture of 0.85, a capacity equivalent to 23 GB was used. Recordings were made. The linear speed at which the information recording medium 28 was rotated was 5 m / sec. In addition, a spectrum analyzer was used to measure the CNR (ie, the ratio of signal amplitude to noise) and the erasure rate.

  First, a peak power (Pp) and a bias power (Pb) were set according to the following procedure in order to determine measurement conditions for determining the number of repetitions. The laser beam 12 is irradiated onto the information recording medium 28 while modulating the power between the peak power (mW) at the high power level and the bias power (mW) at the low power level, and the 2T having a mark length of 0.16 μm is irradiated. The signal was recorded 10 times on the same groove surface of the recording layer 4. After recording the 2T signal 10 times, the CNR was measured. At the time of recording the 2T signal ten times, the bias power was fixed to a constant value, and the CNR was measured under various recording conditions in which the peak power was variously changed. Double power was set to Pp. Next, after recording the 2T signal ten times in the same manner as described above, the signal was reproduced and the amplitude of the 2T signal was measured. Further, the 9T signal was overwritten once on the groove surface, the signal was reproduced, the amplitude of the 2T signal was measured, and the attenuation rate of the 2T signal based on the amplitude measured after recording 10 times was determined as the erasure rate. . In 10 times recording of the 2T signal and once overwriting of the 9T signal, the erasure rate defined as above is fixed for each power condition in which the peak power is fixed to the previously set Pp and the bias power is variously changed. And the center value of the bias power range in which the erasure rate is 25 dB or more was set to Pb. It is desirable that the information recording medium 28 having the structure shown in FIG. 4 satisfy Pp ≦ 6 mW and Pb ≦ 3 mW.

  In the present embodiment, the number of repetitions as an index of the repetition rewriting performance was determined based on the CNR and the erasing rate. The laser light is irradiated onto the information recording medium 28 while power-modulating the laser light with the Pp and Pb set as described above, and the 2T signal is repeatedly recorded a predetermined number of times on the same groove surface, and then the CNR is measured. Then, the erasure rate was determined. In the same manner as described above, the erasure rate is determined by measuring the 2T signal after recording a predetermined number of times and overwriting the 9T signal once on the same, and measuring the 1T signal with respect to the amplitude of the 2T signal measured after recording the predetermined number of times. It was determined from the decay rate of the amplitude of the 2T signal measured after repeated writing. The CNR and the erasure rate were obtained when the number of repetitions was 1, 2, 3, 5, 10, 100, 200, 500, 1000, 2000, 3000, 5000, 7000, and 10000. Based on the CNR and the erasure rate after 10 repetitions, when the CNR decreased by 2 dB or the erasure rate decreased by 5 dB was judged as the limit of repetitive rewriting, and the repetition rewriting performance was evaluated based on the number of repetitions. . Of course, the larger the number of repetitions, the higher the rewrite performance. The number of repetitions of the information recording medium 28 is preferably 10,000 or more.

In the information recording medium 28 of the sample number 10-1 of this embodiment, the order of film formation of each layer on the substrate is opposite to that of the information recording medium 25 as shown in FIG. And the first dielectric layer 2 and the second dielectric layer 6 (HfSiO ₄ ) ₅₄ (Cr _By using a layer (Hf—Cr—O-based material layer) composed of a material having a composition of ₂ O ₃ ) ₄₆ (mol%), good performance was obtained without providing an interface layer. In addition, the measured Rc value (in the flat portion having no unevenness) of the information recording medium 28 of Sample No. 10-1 manufactured in this example was 20%, and the measured Ra value was 3%. From Table 12, it was confirmed that the information recording medium 28 of the sample number 10-1 exhibited the same performance as the information recording medium of the comparative example provided with the first and second interface layers.

In the information recording medium 28 of the sample number 10-1 of the present embodiment, a layer made of a HfSiO ₄ —Cr ₂ O ₃ material is used for both the first and second dielectric layers. A / Zr-Cr-O-based material layer or a Hf / Zr-Cr-Zn-O-based material layer may be used.

In the information recording medium 28 of the present embodiment, the Hf / Zr-Cr-O-based material layer is used for both the first and second dielectric layers, but the present invention is not limited to this. As an example, an Hf / Zr-Cr-O-based material layer or an Hf / Zr-Cr-Zn-O-based material layer is used for one of the first and second dielectric layers, and the other dielectric layer has For example, a conventional material having a composition of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) may be used, and an interface layer may be provided between the other dielectric layer and the recording layer. Also in this case, the same result as in the present example was obtained. Therefore, by using the Hf / Zr-Cr-O-based material layer or the Hf / Zr-Cr-Zn-O-based material layer as the dielectric layer, conventionally, the first and second dielectric layers and the recording layer can be separated. It is possible to reduce at least one, and preferably both, of the two interface layers used between them, and to ensure the same performance as a conventional information recording medium.

(Example 15)
In Example 15, an information recording medium having the same structure as the information recording medium 29 described in Embodiment 5 with reference to FIG. 5 was manufactured.

The information recording medium 29 of this example was manufactured as follows. First, a substrate 101 similar to that of Example 14 was prepared, and a second reflective layer 20 of Ag-Pd-Cu was formed on this substrate 101 with a thickness of 80 nm by using (HfSiO ₄ ) ₅₄ (Cr ₂ O _3). The ₄₆ (mol%) fifth dielectric layer 19 has a thickness of 16 nm, the Ge ₄₅ Sb ₄ Te ₅₁ (atomic%) second recording layer 18 has a thickness of 11 nm, and (HfSiO ₄ ) ₅₄ A fourth dielectric layer 17 of (Cr ₂ O ₃ ) ₄₆ (mol%) was sequentially formed to a thickness of 68 nm by a sputtering method. Thus, the second information layer 22 was formed on the substrate 101.

  The step of forming the second reflective layer 20, the fifth dielectric layer 19, and the fourth dielectric layer 17 is performed in the method of manufacturing the information recording medium 28 according to the fourteenth embodiment. The process was performed under the same conditions as those for forming the body layer 6 and the first dielectric layer 2. The step of forming the second recording layer 18 is the same as the step of forming the recording layer 4 in the method for manufacturing the information recording medium 28 of Example 14, except that a sputtering target having a different composition was used. It was carried out under the conditions.

  Next, the intermediate layer 16 was formed on the second information layer 22 according to the following procedure. First, an ultraviolet curable resin was applied by, for example, spin coating, and a polycarbonate substrate provided with irregularities on the surface was placed on the applied ultraviolet curable resin with the irregularities adhered to each other. The unevenness had a shape complementary to the guide groove to be formed in the intermediate layer 16. Then, the resin was cured by irradiating ultraviolet rays from the polycarbonate substrate side, and the polycarbonate substrate was separated from the intermediate layer 16. Thereby, the intermediate layer 16 made of the cured ultraviolet curable resin and having the guide groove formed by transfer was formed with a thickness of 30 μm.

  Then, a first initialization step was performed. In the first initialization step, the second recording layer 18 of the second information layer 22 is crystallized over almost the entire surface within an annular region having a radius of 22 to 60 mm using a semiconductor laser having a wavelength of 670 nm. I let it.

Next, on the intermediate layer 16 of the laminate obtained as described above, a third dielectric layer 15 of TiO ₂ was formed to a thickness of 15 nm and a first reflective layer 14 of Ag-Pd-Cu was formed. A second dielectric layer 6 of 10 nm thick and of (HfSiO ₄ ) ₄₃ (Cr ₂ O ₃ ) ₅₇ (mol%) having a thickness of 12 nm and of Ge ₄₀ Sn ₅ Sb ₄ Te ₅₁ (atomic%) The first recording layer 13 is formed to have a thickness of 6 nm, and the first dielectric layer 2 of (HfSiO ₄ ) ₄₃ (Cr ₂ O ₃ ) ₅₇ (mol%) is formed to have a thickness of 45 nm by sputtering. did. Thus, the first information layer 21 was formed.

In the step of forming the third dielectric layer 15, a sputtering target (diameter 100 mm, thickness 6 mm) made of a material having a composition of TiO ₂ is used at a power of 400 W and an Ar gas (97%) and an O ₂ gas. (3%), and high-frequency sputtering was performed under a pressure of about 0.13 Pa.

  The step of forming the first reflective layer 14 was performed under the same conditions as the above-described step of forming the second reflective layer 20, except that the layer thickness was changed.

In the step of forming the second dielectric layer 6, a sputtering target (diameter 100 mm, thickness 6 mm) made of a material having a composition of (HfSiO ₄ ) ₄₃ (Cr ₂ O ₃ ) ₅₇ is attached to the film forming apparatus, Argon gas (100%) was introduced at 500 W, and high frequency sputtering was performed under a pressure of about 0.13.

  In the step of forming the first recording layer 13, a sputtering target (diameter 100 mm, thickness 6 mm) made of a Ge—Sn—Sb—Te-based material was attached to the film forming apparatus, and a power of 50 W and an Ar gas (100%) were used. ) Was introduced to perform DC sputtering. The pressure during sputtering was about 0.13 Pa.

  The step of forming the first dielectric layer 2 was performed in the same manner as the step of forming the second dielectric layer 6 except that the layer thickness was changed. As a result, the first dielectric layer 2 and the second dielectric layer 6 have substantially the same composition.

  After the first dielectric layer 2 is formed on the substrate 101 as described above to form a laminate, an ultraviolet curable resin is applied on the first dielectric layer 2 and the applied ultraviolet light is applied. On the curable resin, a circular polycarbonate substrate having a diameter of 120 mm and a thickness of 65 μm was adhered as the dummy substrate 110. Then, ultraviolet rays were irradiated from the side of the dummy substrate 110 to cure the resin. As a result, the adhesive layer 9 made of the cured resin was formed with a thickness of 10 μm, and at the same time, the dummy substrate 110 was bonded to the laminate through the adhesive layer 9.

  After bonding the dummy substrate 110, a second initialization step was performed. In the second initialization step, the first recording layer 13 of the first information layer 21 is crystallized over almost the entire surface within an annular region having a radius of 22 to 60 mm using a semiconductor laser having a wavelength of 670 nm. I let it. Thus, the production of the information recording medium 29 of the sample number 11-1 was completed.

  For the information recording medium 29 of the sample number 11-1 obtained as described above, the adhesion of the dielectric layer and the repetitive rewriting performance of the information recording medium were evaluated for each of the first information layer 21 and the second information layer 22. did. Table 13 shows these results together with the peak power (Pp) and the bias power (Pb) obtained in the evaluation of the rewrite performance.

  In the present embodiment, the evaluation of the adhesion of the dielectric layer in the information recording medium 29 was performed under the same conditions as in the first embodiment, but the presence or absence of peeling of each of the first information layer 21 and the second information layer 22 was determined. It differs in the points examined. The evaluation of the repetitive rewriting performance of the information recording medium 29 was performed under substantially the same conditions as in Example 14. However, each of the first information layer 21 and the second information layer 22 of the information recording medium 29 had a capacity of 23 GB. The difference is that recording is performed and the number of repetitions is checked for each of the first information layer 21 and the second information layer 22. When recording on the first information layer 21, the laser beam 12 is focused on the first recording layer 13, and when recording on the second information layer 22, the laser beam 12 is focused on the second recording layer 18. I let it. In consideration of the upper limit of the laser power of the system, it is desirable that the first information layer 21 satisfies Pp ≦ 12 mW and Pb ≦ 6 mW.

The information recording medium 29 of the sample number 11-1 of this embodiment is different from the information recording medium 25 as shown in FIG. 1 in the order of film formation of each layer on the substrate, and there are two or more information layers on the substrate. And recording conditions. The recording capacity of the information recording medium 29 of the sample number 11-1 is about ten times that of the information recording medium 25 shown in FIG. However, regardless of these differences, as the first dielectric layer 2, the second dielectric layer 6, the fourth dielectric layer 17, and the fifth dielectric layer 19, a HfSiO ₄ —Cr ₂ O ₃ system is used. By using a layer made of a material, good performance was obtained without providing an interface layer. The Rc design value of the first information layer 21 of the information recording medium 29 of the sample number 11-1 manufactured in the present example (in the flat portion having no unevenness) is 6%, and the Ra design value is 0.7%. Met. The Rc design value of the second information layer 22 was 25%, and the Ra design value was 3%.

In the information recording medium 29 of the sample number 11-1 of the present embodiment, all of the first dielectric layer 2, the second dielectric layer 6, the fourth dielectric layer 17, and the fifth dielectric layer 19 HfSiO ₄ -Cr ₂ was used a system layer of a material of the O _3, other Hf / Zr-Cr-O-based material layer (e.g., HfO ₂ -Cr ₂ O ₃ system and HfO ₂ -Cr ₂ O ₃ A layer made of a material such as -SiO ₂ or a Hf / Zr-Cr-Zn-O-based material layer (for example, a material obtained by mixing ZnS, ZnSe or ZnO with HfO ₂ -Cr ₂ O ₃ -SiO ₂₎ A good performance was obtained even when the layer composed of) was used as the dielectric layer.

In the information recording medium 29 of the present embodiment, all of the first dielectric layer 2, the second dielectric layer 6, the fourth dielectric layer 17, and the fifth dielectric layer 19 have Hf / Zr− Although a Cr-O-based material layer is used, the present invention is not limited to this. As an example, an Hf / Zr—Cr—O-based material layer or an Hf / Zr—Cr—O-based material layer is used for at least one of these dielectric layers, and a conventional (ZnS) is used for the remaining dielectric layers. A material having a composition of ₈₀ (SiO ₂ ) ₂₀ (mol%) may be used, and an interface layer may be provided between the remaining dielectric layer and the recording layer. In this case, the same result as in the present embodiment was obtained.

In the information recording medium 29 of this embodiment, a layer made of TiO ₂ is used as the third dielectric layer 15, but instead of this, a layer made of (HfO ₂ ) ₃₀ (Cr ₂ O ₃ ) _{70 is used.} May be used. In this case, equivalent performance was obtained in the first information layer 21.

Further, in the information recording medium 29 of this embodiment, two types of HfSiO ₄ —Cr ₂ O ₃ are adopted, and the fifth and fourth dielectric layers 19 and 17 are formed of one material, and the other is used. The second and first dielectric layers 6 and 2 were made of the above material. The present invention is not limited to this, and these four dielectric layers may be formed of the same material, or may be formed of different materials. In that case, the same good performance as the result of this example was obtained.

(Example 16)
In Example 16, an information recording medium having the same structure as the information recording medium 30 described in Embodiment 6 with reference to FIG. 6 was manufactured. In the information recording medium 30 of the present embodiment, unlike the above-described information recording media of Examples 1 to 15, an Hf—Cr—O-based material layer is formed on the first interface layer 3 and the second interface layer 5. Using.

The information recording medium 30 of the present example was manufactured as follows. First, a substrate 1 similar to that of Example 1 is prepared, and a first dielectric layer 102 of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) is formed on this substrate 1 to a thickness of 150 nm by ( The first interface layer 3 of HfSiO ₄ ) ₄₃ (Cr ₂ O ₃ ) ₅₇ (mol%) has a thickness of 5 nm, and the recording layer 4 of Ge ₂₇ Sn ₈ Sb ₁₂ Te ₅₃ (atomic%) has a thickness of 9 nm. Then, a second interface layer 5 of (HfSiO ₄ ) ₄₃ (Cr ₂ O ₃ ) ₅₇ (mol%) having a thickness of 5 nm and a second dielectric layer of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) The body layer 106 has a thickness of 50 nm, the light absorption correction layer 7 of Ge ₈₀ Cr ₂₀ (atomic%) has a thickness of 40 nm, and the reflection layer 8 of Ag-Pd-Cu has a thickness of 80 nm. Films were sequentially formed. Here, the respective materials of the first dielectric layer 102 and the second dielectric layer 106 are the same as those provided in the conventional information recording medium 31 described above with reference to FIG.

This information recording medium 30 is a conventional information recording medium 31 manufactured in Example 1 (see FIG. 10) except that the materials of the first interface layer 3 and the second interface layer 5 are different. ), Except that the steps of forming the first interface layer 3 and the second interface layer 5 were omitted. In the step of forming the first interface layer 3 and the second interface layer 5, a sputtering target (100 mm in diameter, thickness 100 mm) made of a material having a composition of (HfSiO ₄ ) ₄₃ (Cr ₂ O ₃ ) ₅₇ (mol%) 6 mm) was attached to a film forming apparatus, and high-frequency sputtering was performed at a power of 500 W and an Ar gas (100%) under a pressure of about 0.13 Pa.

  With respect to the information recording medium 30 of Sample No. 12-1 obtained as described above, the adhesion of the dielectric layer and the repetitive rewriting performance of the information recording medium were evaluated in substantially the same manner as described in Example 1. However, in the present example, the adhesion was evaluated between the recording layer 4 and the interface layer in contact with the recording layer, more specifically, at least one of the first interface layer 3 and the second interface layer 5 with the recording layer. It was carried out by checking whether or not peeling occurred between the samples. The evaluation of the repetitive rewriting performance was performed by performing land recording as well as groove recording (that is, by land-groove recording) and checking the number of repetitions for each of the groove recording and the land recording. Table 14 shows the results. In addition, for comparison, Table 14 also shows the results of similarly evaluating the information recording medium 31 of the conventional configuration shown in FIG. 10 manufactured in Example 1.

As shown in Table 14, in the information recording medium 30 of the sample No. 12-1 of the present example using (HfSiO ₄ ) ₄₃ (Cr ₂ O ₃ ) ₅₇ (mol%) as the material of the interface layer, the comparative example was used. The same performance as that of the conventional information recording medium 31 was obtained.

  The number of layers of the information recording medium of this embodiment using the Hf—Cr—O-based material layer as the interface layer is the same as the conventional one and does not decrease. However, such an interface layer made of an Hf—Cr—O-based material can be formed by sputtering in an atmosphere of only Ar gas, not by reactive sputtering as in the conventional Ge—Cr—N interface layer. It is. Therefore, according to this embodiment, the composition variation and the film thickness distribution of the interface layer itself are smaller than those of the conventional interface layer of Ge—Cr—N, and the easiness of manufacture and stability can be improved.

In the information recording medium 30 of the sample number 12-1 of the present embodiment, the first interface layer 3 and the second interface layer 5 are (HfSiO ₄ ) ₄₃ (Cr ₂ O ₃ ) ₅₇ (mol%). Although a layer made of a material having a composition (Hf—Cr—O-based material layer) was used, this composition is merely an example, and other Hf / Zr—Cr—O-based material layers or Hf / Zr—Cr—Zn An -O-based material layer may be used. The first interface layer 3 and the second interface layer 5 are layers having different compositions selected from a Hf / Zr-Cr-O-based material layer and a Hf / Zr-Cr-Zn-O-based material layer. It may be.

(Example 17)
Example 17 has a structure similar to that of the information recording medium 27 described in Embodiment 3 with reference to FIG. 3, and the second dielectric layer 6 is an Hf—Zr—Cr—O-based material layer. A certain thing (sample number 13-1) was produced.

The information recording medium 27 of this embodiment was manufactured as follows. First, a substrate 1 similar to that of Example 1 is prepared, and a first dielectric layer 102 of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) is formed on this substrate 1 to a thickness of 150 nm by ( The first interface layer 103 of ZrO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (SiO ₂ ) ₂₅ (mol%) has a thickness of 2 nm and the recording layer 4 of Ge ₂₇ Sn ₈ Sb ₁₂ Te ₅₃ (atomic%). To a second dielectric layer 6 of (HfO ₂ ) ₃₀ (ZrO ₂ ) ₁₀ (Cr ₂ O ₃ ) ₃₀ (SiO ₂ ) ₃₀ (mol%) with a thickness of 9 nm and a thickness of Ge ₈₀ The light absorption correction layer 7 of Cr ₂₀ (atomic%) was formed in a thickness of 40 nm, and the reflection layer 8 of Ag-Pd-Cu was formed in a thickness of 80 nm by a sputtering method.

The information recording medium 27 of the present embodiment is different from the information recording medium 27 in that a film forming step of the first interface layer 103 is added between the film forming step of the first dielectric layer 102 and the film forming step of the recording layer 4. The information recording medium of Example 1 was manufactured in the same manner as in the case of the information recording medium of Sample No. 1-1, except that the step of forming the dielectric layer 6 was changed. In the step of forming the first interface layer 103, a sputtering target (diameter 100 mm, thickness 6 mm) having a composition of ((ZrO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (SiO ₂ ) ₂₅ (mol%) is used. The high-frequency sputtering was carried out under the pressure of about 0.13 Pa at a power of 500 W with Ar gas (100%) introduced into the film forming apparatus and gas introduced into the film forming apparatus. In the film forming step of ( ₁ ), a sputtering target (diameter 100 mm, thickness 6 mm) having a composition of (HfO ₂ ) ₃₀ (ZrO ₂ ) ₁₀ (Cr ₂ O ₃ ) ₃₀ (SiO ₂ ) ₃₀ (mol%) is formed by a film forming apparatus. And high-frequency sputtering was performed under a pressure of about 0.13 Pa at a power of 500 W under an Ar gas (100%) gas introduced into the film forming apparatus. The layer formation step, the bonding step of the dummy substrate 10, and the initialization step were performed in the same manner as in Example 1.

  With respect to the information recording medium 27 of the sample number 13-1 obtained as described above, the adhesion of the dielectric layer and the rewriting performance of the information recording medium were evaluated in substantially the same manner as described in Example 1. However, in the present example, the evaluation of adhesion was performed by checking whether or not peeling occurred between the recording layer 4 and the second dielectric layer 6 in contact with the recording layer. The evaluation of the repetitive rewriting performance was performed by performing land recording as well as groove recording (that is, by land-groove recording) and checking the number of repetitions for each of the groove recording and the land recording. Table 15 shows these results together with the peak power (Pp) and the bias power (Pb) obtained during the evaluation of the rewrite performance. In addition, for comparison, Table 15 also shows the results of similarly evaluating the information recording medium 31 of the conventional configuration shown in FIG. 10 manufactured in Example 1.

As shown in Table 15, the second dielectric layer 6 was made of (HfO ₂ ) ₃₀ (ZrO ₂ ) ₁₀ (Cr ₂ O ₃ ) ₃₀ (SiO ₂ ) ₃₀ (mol%) as the material of the second dielectric layer 6. In the information recording medium 27 of the sample number 13-1, performance equivalent to that of the information recording medium 31 of the comparative example having the conventional configuration was obtained.

In this embodiment, as the Hf-Zr-Cr-O-based material layer, (HfO ₂ ) ₃₀ (ZrO ₂ ) ₁₀ (Cr ₂ O ₃ ) ₃₀ (SiO ₂ ) ₃₀ (mol%) (Hf _8.3 Zr _2.8 Cr _16.7 Si _8.3 O _63.9 (atomic%)) was used. This composition is an example, and the mixing ratio of HfO ₂ and ZrO ₂ is 20 mol% or more and 70 mol% or less, the mixing ratio of Cr ₂ O ₃ is 20 mol% or more and 60 mol% or less, and the mixing ratio of SiO ₂ is It has been found that good results can be obtained in the same manner as in the present example by using an Hf / Zr—Cr—O-based material layer having a content of 10 mol% or more and 40 mol% or less. Further, the total content of Hf and Zr is 30 at% or less, the Cr content is 7 to 37 at%, the Si content is 14 at% or less, and the O content is It was also found that good results were obtained with an information recording medium employing an Hf / Zr-Cr-O-based material layer having an amount of 40 atomic% or more and 80 atomic% or less.

(Example 18)
In the embodiment, a DVD-ROM which is a read-only information recording medium for reproducing information by optical means was manufactured. In this embodiment, a reflective layer having a thickness of 30 nm is formed on the surface of a substrate on which signal pits of information corresponding to 4.7 GB have been formed in advance, and a dielectric layer having a thickness of 50 nm is formed on the reflective layer. Then, a DVD-ROM was manufactured by bonding a dummy substrate via an adhesive layer. Reflective layer is formed using an Ag-Pd-Cu alloy, the composition is a dielectric layer _{(HfO 2) 30 (ZrO 2} ) 30 (Cr 2 O 3) 20 using a target which is (SiO _{2) 20} , Formed by sputtering. In the obtained information recording medium, no separation occurred between the dielectric layer and the reflective layer, and the adhesion of the dielectric layer to the reflective layer was high. In addition, good reproduction jitter was obtained. From this example, it was confirmed that the Hf / Zr-Cr-O-based material can be used in a read-only medium.

(Example 19)
In Examples 1 to 18 described above, an information recording medium for recording information by optical means was manufactured. In Example 19, an information recording medium 207 for recording information by electric means as shown in FIG. Produced. The information recording medium 207 of this embodiment is a so-called memory.

The information recording medium 207 of this example was manufactured as follows. First, a Si substrate 201 having a length of 5 mm, a width of 5 mm, and a thickness of 1 mm whose surface was nitrided was prepared, and an Au lower electrode 202 was formed on the substrate 201 in an area of 1.0 mm × 1.0 mm. It was formed with a thickness of 0.1 μm. A phase change portion 205 of Ge ₃₈ Sb ₁₀ Te ₅₂ (the compound is expressed as Ge ₈ Sb ₂ Te ₁₁ ) is formed on the lower electrode 202 in a circular region having a diameter of 0.2 mm to a thickness of 0.1 μm. The heat insulating part 206 of (HfO ₂ ) ₅₆ (Cr ₂ O ₃ ) ₃₀ (SiO ₂ ) ₁₄ is formed into a 0.6 mm × 0.6 mm area (excluding the phase change part 205). An Au upper electrode 204 was formed to have the same thickness and a thickness of 0.1 μm in an area of 0.6 mm × 0.6 mm. All of the lower electrode 202, the phase change part 205, the heat insulating part 206, and the upper electrode 204 were sequentially laminated by a sputtering method.

In the step of forming the phase change portion 205, a sputtering target (100 mm in diameter and 6 mm in thickness) made of a Ge—Sb—Te-based material is attached to the film forming apparatus, and Ar gas (100%) is introduced at a power of 100 W. DC sputtering was performed. The pressure during sputtering was about 0.13 Pa. In the step of forming the heat insulating portion 206, a sputtering target (100 mm in diameter, 6 mm in thickness) made of a material having a composition of (HfO ₂ ) ₅₆ (Cr ₂ O ₃ ) ₃₀ (SiO ₂ ) ₁₄ is supplied to a film forming apparatus. Attachment, power 500W, Ar gas (100%) was introduced, and high frequency sputtering was performed under a pressure of about 0.13Pa. Sputtering in these steps was performed by covering regions other than the surface on which a film is to be formed with a mask jig so that the phase change portion 205 and the heat insulating portion 206 would not be stacked on each other. Note that the order of forming the phase change portion 205 and the heat insulating portion 206 does not matter, and either may be performed first.

  The phase change unit 205 and the heat insulation unit 206 constitute a recording unit 203, and the phase change unit 205 corresponds to a recording layer according to the present invention, and the heat insulation unit 206 corresponds to Hf / Zr-Cr-O according to the present invention. Corresponds to the system material layer.

  The step of forming the lower electrode 202 and the step of forming the upper electrode 204 can be performed by a general method in the field of an electrode forming technique by a sputtering method, and a detailed description thereof will be omitted.

  It was confirmed by the system shown in FIG. 9 that a phase change occurred in the phase change portion 205 by applying electric energy to the information recording medium 207 of the present example manufactured as described above. The cross-sectional view of the information recording medium 207 illustrated in FIG. 9 illustrates a cross section of the information recording medium 207 illustrated in FIG. 8 cut along the line AB in the thickness direction.

  More specifically, as shown in FIG. 9, by bonding the two application units 212 to the lower electrode 202 and the upper electrode 204 with Au lead wires, respectively, the electric writing / reading device 214 is applied via the application unit 212. It was connected to an information recording medium (memory) 207. In the electric writing / reading device 214, a pulse generator 208 is connected between a lower electrode 202 and an application unit 212 connected to the upper electrode 204 via a switch 210. Are connected via the switch 211. The resistance measurement device 209 was connected to the determination unit 213 that determines the level of the resistance value measured by the resistance measurement device 209. A current pulse is caused to flow between the upper electrode 204 and the lower electrode 202 by the pulse generator 208 via the application unit 212, and the resistance between the lower electrode 202 and the upper electrode 204 is measured by a resistance measuring device 209. The level of the value was determined by the determination unit 213. Generally, since the resistance value changes due to the phase change of the phase change unit 205, the state of the phase of the phase change unit 205 can be known based on the determination result.

  In the case of this embodiment, the melting point of the phase change portion 205 was 630 ° C., the crystallization temperature was 170 ° C., and the crystallization time was 130 ns. The resistance value between the lower electrode 202 and the upper electrode 204 was 1000Ω when the phase change part 205 was in the amorphous phase state, and was 20Ω when the phase change part 205 was in the crystalline phase state. When the phase change portion 205 is in an amorphous phase state (ie, in a high resistance state), a current pulse of 20 mA and 150 ns is applied between the lower electrode 202 and the upper electrode 204, and the current between the lower electrode 202 and the upper electrode 204 is increased. , The phase change portion 205 changed from an amorphous phase state to a crystalline phase state. Next, when the phase change section 205 is in a crystalline phase state (that is, in a low resistance state), a current pulse of 200 mA and 100 ns is applied between the lower electrode 202 and the upper electrode 204. During this time, the phase change portion 205 changed from a crystalline phase to an amorphous phase.

From the above results, a layer made of a material having a composition of (HfO ₂ ) ₅₆ (Cr ₂ O ₃ ) ₃₀ (SiO ₂ ) ₁₄ is used as the heat insulating portion 206 around the phase change portion 205 and electric energy is applied. As a result, a phase transformation can be caused in the phase change portion (recording layer), and thus, it was confirmed that the information recording medium 207 has a function of recording information.

As in the present embodiment, when a heat insulating portion 206 of (HfO ₂ ) ₅₆ (Cr ₂ O ₃ ) ₃₀ (SiO ₂ ) ₁₄ as a dielectric is provided around the columnar phase change portion 205, the upper electrode 204 is formed. By applying a voltage between the phase change portion 205 and the lower electrode 202, the current flowing through the phase change portion 205 can be effectively prevented from escaping to the peripheral portion. As a result, the temperature of phase change section 205 can be efficiently increased by Joule heat generated by the current. In particular, when the phase change portion 205 is changed to an amorphous phase state, a process of temporarily melting Ge ₃₈ Sb ₁₀ Te ₅₂ of the phase change portion 205 and rapidly cooling is required. This melting of the phase change portion 205 can occur with a smaller current by providing the heat insulation portion 206 around the phase change portion 205.

(HfO ₂ ) ₅₆ (Cr ₂ O ₃ ) ₃₀ (SiO ₂ ) ₁₄ of the heat insulating portion 206 has a high melting point and is unlikely to cause atomic diffusion by heat, and is therefore applied to an electric memory such as the information recording medium 207. It is possible. When the heat insulating portion 206 exists around the phase change portion 205, the heat insulating portion 206 acts as a barrier, and the phase change portion 205 is substantially electrically and thermally isolated in the plane of the recording portion 203. By taking advantage of this, a plurality of phase change units 205 are provided in the information recording medium 207 in a state of being isolated from each other by the heat insulating unit 206, so that the memory capacity of the information recording medium 207 can be increased, and an access function and a switching function can be provided. Can be improved. It is also possible to connect a plurality of information recording media 207 themselves.

  As described above, the information recording medium of the present invention has been described through various embodiments. One or a plurality of Hf / Zr may be used for both the information recording medium for recording by optical means and the information recording medium for recording by electric means. A -Cr-O-based material layer and an Hf / Zr-Cr-Zn-O-based material layer can be used. According to the information recording medium of the present invention including such a layer, a configuration which has not been realized can be realized, and / or superior performance can be obtained as compared with a conventional information recording medium.

  The information recording medium of the present invention has an Hf / Zr-Cr-O-based material layer or an Hf / Zr-Cr-Zn-O-based material layer in which constituent elements are less likely to diffuse into the recording layer even when in contact with the recording layer. It is useful as an optical information recording medium having a small number of layers, which does not require an interface layer between a recording layer and a dielectric layer.

FIG. 1 is a partial cross-sectional view illustrating an example of an optical information recording medium of the present invention. FIG. 4 is a partial sectional view showing another example of the optical information recording medium of the present invention. FIG. 11 is a partial cross-sectional view showing still another example of the optical information recording medium of the present invention. FIG. 11 is a partial cross-sectional view showing still another example of the optical information recording medium of the present invention. FIG. 11 is a partial cross-sectional view showing still another example of the optical information recording medium of the present invention. FIG. 11 is a partial cross-sectional view showing still another example of the optical information recording medium of the present invention. It is a triangle diagram which shows the composition range of the material represented by Formula (21). FIG. 1 is a schematic diagram illustrating an example of an information recording medium of the present invention in which information is recorded by applying electric energy. FIG. 9 is a schematic diagram showing an example of a system using the information recording medium shown in FIG. FIG. 11 is a partial cross-sectional view illustrating an example of a conventional information recording medium.

Explanation of reference numerals

1,101,201 substrate;
2,102 first dielectric layer;
3,103 first interfacial layer;
4 recording layer;
5,105 second interfacial layer;
6,106 second dielectric layer;
7 light absorption correction layer;
8 reflective layer;
9 adhesive layer;
10,110 dummy substrate;
12 laser light;
13 first recording layer;
14 first reflective layer;
15 third dielectric layer;
16 intermediate layer;
17 fourth dielectric layer;
18 second recording layer;
19 fifth dielectric layer;
20 a second reflective layer;
21 first information layer;
22 second information layer;
23 Groove surface;
24 Land surface;
25, 26, 27, 28, 29, 30, 31, 207 Information recording medium;
202 lower electrode;
203 recording unit;
204 upper electrode;
205 phase change portion (recording layer);
206 heat insulating part (dielectric layer);
208 pulse generator;
209 resistance measuring instrument;
210, 211 switches;
212 application unit;
213 judgment unit;
214 Electrical writing / reading device.

Claims (22)

  An information recording medium for recording and / or reproducing information by light irradiation or application of electrical energy, wherein the first metal component includes Hf or Hf and Zr, the second metal component includes Cr, An Hf / Zr-Cr-O-based material layer containing O, wherein in the Hf / Zr-Cr-O-based material layer, the content of the first metal component is 30 atom% or less; An information recording medium having a content of 7 atomic% or more and 37 atomic% or less. The Hf / Zr—Cr—O-based material layer is represented by Formula (1):

(Wherein, M represents the first metal component, and Q and R are respectively 0 <Q ≦ 30, 7 ≦ R ≦ 37, and 20 ≦ Q + R ≦ 60)
2. The information recording medium according to claim 1, substantially consisting of a material represented by: The Hf / Zr—Cr—O-based material layer further contains Si, and the formula (2):

(Wherein M represents the first metal component, U, V, and T are 0 <U ≦ 30, 7 ≦ V ≦ 37, and 0 <T ≦ 14, and 20 ≦ U + V + T ≦ 60, respectively) is there)
2. The information recording medium according to claim 1, substantially consisting of a material represented by: The Hf / Zr—Cr—O-based material layer has the formula (11):

(Wherein, M represents the first metal component, and N satisfies 20 ≦ N ≦ 80)
2. The information recording medium according to claim 1, substantially consisting of a material represented by: The Hf / Zr—Cr—O-based material layer containing Si is represented by Formula (21):

(Wherein, M represents the first metal component, X and Y are respectively 20 ≦ X ≦ 70 and 20 ≦ Y ≦ 60, and 60 ≦ X + Y ≦ 90)
4. The information recording medium according to claim 3, substantially consisting of a material represented by: The material represented by the formula (21) contains MO ₂ and SiO ₂ in substantially equal proportions, and the material represented by the formula (22):

(In the formula, M represents the first metal component, and Z satisfies 25 ≦ Z ≦ 67.)
The information recording medium according to claim 5, which is represented by: An information recording medium for recording and / or reproducing information by light irradiation or application of electrical energy, wherein the first metal component includes Hf or Hf and Zr, the second metal component includes Cr, and the formula ( 3):

(Wherein M represents the first metal component, D is ZnS, ZnSe or ZnO, and C, E and F are respectively 20 ≦ C ≦ 60, 20 ≦ E ≦ 60, and 10 ≦ F ≦ 40 And 60 ≦ C + E + F ≦ 90)
An information recording medium including a layer substantially composed of a Hf / Zr-Cr-Zn-O-based material represented by the following formula: The material represented by the formula (3) contains MO ₂ and SiO ₂ in substantially equal proportions, and the material represented by the formula (31):

(Wherein, M represents a first metal component, D is ZnS, ZnSe or ZnO, A and B are 25 ≦ A ≦ 54 and 25 ≦ B ≦ 63, respectively, and 50 ≦ A + B ≦ 88)
The information recording medium according to claim 7, represented by: The information recording medium according to claim 1, further comprising a recording layer. The recording layer is composed of Ge-Sb-Te, Ge-Sn-Sb-Te, Ge-Bi-Te, Ge-Sn-Bi-Te, Ge-Sb-Bi-Te, Ge-Sn-Sb-Bi-Te, The information recording medium according to claim 9, wherein the information recording medium includes any one material selected from Ag-In-Sb-Te and Sb-Te. The information recording medium according to claim 10, wherein the thickness of the recording layer is 15 nm or less. The information recording medium according to any one of claims 1 to 11, comprising two or more recording layers. A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer are formed in this order on one surface of the substrate, and the first dielectric layer and the second dielectric layer are formed in this order. At least one of the dielectric layers is the Hf / Zr-Cr-O-based material layer or the Hf / Zr-Cr-Zn-O-based material layer, and is in contact with the recording layer. 13. The information recording medium according to any one of claims 12 to 12. A reflection layer, a second dielectric layer, a recording layer, and a first dielectric layer are formed in this order on one surface of the substrate, and the first dielectric layer and the second dielectric layer are formed in this order. At least one of the dielectric layers is the Hf / Zr-Cr-O-based material layer or the Hf / Zr-Cr-Zn-O-based material layer, and is in contact with the recording layer. 13. The information recording medium according to any one of claims 12 to 12. An information recording medium for recording and / or reproducing information by light irradiation or application of electrical energy, wherein the first metal component includes Hf or Hf and Zr, the second metal component includes Cr, An Hf / Zr—Cr—O-based material layer containing O and having a content of the first metal component of 30 at% or less and a content of the second metal component of 7 at% or more and 37 at% or less; A method for manufacturing an information recording medium, comprising: forming the Hf / Zr-Cr-O-based material layer by a sputtering method. In the step of forming the Hf / Zr—Cr—O-based material layer by a sputtering method, the formula (10):

(Wherein, M represents the first metal component, J and K are respectively 3 ≦ J ≦ 24, 11 ≦ K ≦ 36, and 34 ≦ J + K ≦ 40)
The method for producing an information recording medium according to claim 15, wherein a sputtering target substantially consisting of a material represented by the following formula is used. In the step of forming the Hf / Zr—Cr—O-based material layer by a sputtering method, the formula (20):

(Wherein, M represents the first metal component, G, H and L are respectively 4 ≦ G ≦ 21, 11 ≦ H ≦ 30, and 2 ≦ L ≦ 12, and 34 ≦ G + H + L ≦ 40. )
The method for manufacturing an information recording medium according to claim 15, wherein the Hf / Zr-Cr-O-based material layer containing Si is formed using a sputtering target substantially consisting of a material represented by the following formula: In the step of forming the Hf / Zr—Cr—O-based material layer by a sputtering method, the formula (110):

(Wherein, M represents a first metal component, and n satisfies 20 ≦ n ≦ 80)
The method for producing an information recording medium according to claim 15, wherein a sputtering target substantially consisting of a material represented by the following formula is used. In the step of forming the Hf / Zr—Cr—O-based material layer by a sputtering method, the formula (210):

(Where M represents the first metal component, x and y are respectively 20 ≦ x ≦ 70, 20 ≦ y ≦ 60, and 60 ≦ x + y ≦ 90)
The method for manufacturing an information recording medium according to claim 15, wherein the Hf / Zr-Cr-O-based material layer containing Si is formed using a sputtering target substantially consisting of a material represented by the following formula: The material represented by the formula (210) contains MO ₂ and SiO ₂ at substantially the same ratio, and the material represented by the formula (220):

(Wherein, M represents the first metal component, and z satisfies 25 ≦ z ≦ 67)
20. The method for manufacturing an information recording medium according to claim 19, which is a material represented by the following formula: An information recording medium for recording and / or reproducing information by light irradiation or application of electric energy, wherein Hf / Hf and Zr are contained as a first metal component, and Hf / is a material containing Cr as a second metal component. What is claimed is: 1. A method for producing an information recording medium having a layer substantially composed of a Zr-Cr-Zn-O-based material, wherein the layer substantially composed of the Hf / Zr-Cr-Zn-O-based material is subjected to a sputtering method. In this step, the step of forming formula (30):

(Wherein, M represents the first metal component, D is ZnS, ZnSe or ZnO, c, e and f are respectively 20 ≦ c ≦ 60 and 20 ≦ e ≦ 60, 10 ≦ f ≦ 40 And 60 ≦ c + e + f ≦ 90)
A method for producing an information recording medium using a sputtering target substantially consisting of a material represented by the following formula: The material represented by the formula (30) contains MO ₂ and SiO ₂ in substantially equal proportions, and the material represented by the formula (310):

(Wherein M represents the first metal component, D is ZnS, ZnSe or ZnO, a and b are 25 ≦ a ≦ 54 and 25 ≦ b ≦ 63, respectively, and 50 ≦ a + b ≦ 88)
22. The method for manufacturing an information recording medium according to claim 21, which is a material represented by:

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