JP4210620B2 - Information recording medium and manufacturing method thereof - Google Patents

Description

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

As an example of the basic configuration of the optical information recording medium, for example, a substrate in which a first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer are formed in this order on the surface of the substrate. . The first dielectric layer and the second dielectric layer adjust the optical distance to increase the light absorption efficiency of the recording layer, and increase the difference between the reflectance of the crystalline phase and the reflectance of the amorphous phase. It has a function to increase the signal amplitude. It also has the function of protecting the recording layer from moisture and the like. As a material of the dielectric layer, for example, a mixture of 80 mol% ZnS and 20 mol% SiO ₂ (hereinafter referred to as “(ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%)” or “(ZnS ) ₈₀ (SiO ₂ ) ₂₀ ”, and the same applies to other mixtures) (see, for example, Patent Document 1). This material is an amorphous material, has low thermal conductivity, high transparency, and high refractive index. In addition, the film formation rate during film formation is high, and the mechanical properties and moisture resistance are also excellent. Thus, (ZnS) ₈₀ (SiO ₂ ) ₂₀ has been put into practical use as a material suitable for forming a dielectric layer.

  Along with the recent increase in density, the recording layer has been designed to be about 1/3 as thin as the first practical application in 1990. This is because in order to record small marks well, the heat capacity of the recording layer is reduced, and after the temperature rises, the heat is quickly released to the reflective layer side.

The present inventors have found a problem of (ZnS) ₈₀ (SiO ₂ ) _{20 as} the recording layer is made thinner. That is, when rewriting is performed by irradiating the recording layer with a laser beam, S in (ZnS) ₈₀ (SiO ₂ ) ₂₀ diffuses into the recording layer, and the rewriting performance is remarkably lowered. In order to prevent this diffusion, the present inventors have proposed providing an interface layer between the first dielectric layer and the recording layer and between the recording layer and the second dielectric layer. (For example, refer nonpatent literature 1.). A nitride containing Ge was disclosed as a material for the interface layer (see, for example, Patent Document 2). As a matter of course, a material containing S is not suitable for the interface layer. By providing the interface layer, the repeated rewriting performance was dramatically improved. As in the information recording medium 31 shown in FIG. 12, the 4.7 GB / DVD-RAM disc that has already been put to practical use is provided with an interface layer, and the first dielectric layer 102 is formed on the surface of the substrate 1. The first interface layer 103, the recording layer 4, the second interface layer 105, the second dielectric layer 106, the light absorption correction layer 7 and the reflection layer 8 are formed in this order, and the dummy substrate 10 is further bonded to the adhesive layer. 9 is bonded to the reflective layer 8 (see, for example, Patent Document 3). This configuration has a large capacity and excellent repeated rewriting performance.

  The layer made of nitride containing Ge can be formed by reactively forming Ge or an alloy containing Ge in a high pressure atmosphere by mixing Ar gas and nitrogen gas. Since the repeated rewriting performance or moisture resistance depends on the degree of nitridation of Ge, the film forming conditions are strictly determined. In particular, reactive film formation under high pressure conditions is highly dependent on the structure of the film formation apparatus and the film formation conditions. For example, when taking over from an experimental film formation apparatus to a mass production film formation apparatus, it may take time to determine optimum pressure and gas flow conditions. Because of such problems, an interface layer that can be formed by non-reactive film formation, that is, a material that can be formed in an Ar gas low-pressure atmosphere and does not contain S is required. If the interface layer can be used as a dielectric layer, the number of layers may be reduced.

In addition, as a material suitable for the interface layer of the information recording medium, there is a material proposed from the relationship of thermal conductivity (see, for example, Patent Document 4).
Patent No. 1959977 (Claims) JP 09-83298 A (Claims) JP 2001-322357 A (Claims) JP 2001-67722 A (Claims) Yamada et al., Japanese Journal of Applied Physics, Volume 37, 1998, p. 2104-2110 (N. Yamada et al. Japanese Journal of Applied Physics Vol. 37 (1998) pp. 2104-211)

In order to solve the above-mentioned conventional problems, the present inventors are an interface layer that can be formed by non-reactive film formation and is excellent in moisture resistance and repeated rewritability, and can be provided in contact with the recording layer. A dielectric material mixed with ZrO ₂ , SiO _2, and Cr ₂ O ₃ that can be used as the first or second dielectric layer and exhibits excellent repetitive rewriting performance is proposed separately. In this ZrO ₂ —SiO ₂ —Cr ₂ O ₃ , ZrO ₂ and SiO ₂ are transparent and thermally stable materials, and Cr ₂ O ₃ is a material having excellent adhesion to a chalcogen-based recording layer. . Therefore, it is possible to achieve both thermal stability and adhesion by mixing these three oxides. In order to ensure adhesion, a composition containing 30 mol% or more of Cr ₂ O ₃ is more preferable. An information recording medium to which this ZrO ₂ —SiO ₂ —Cr ₂ O ₃ material is applied as an interface layer or a dielectric layer has excellent repeated rewriting performance and moisture resistance.

However, in order to be a material suitable for forming the interface layer or the dielectric layer, low thermal conductivity and transparency are also required. In ZrO ₂ —SiO ₂ —Cr ₂ O ₃ , these two performances did not reach (ZnS) ₈₀ (SiO ₂ ) ₂₀ . ZrO ₂ and SiO ₂ were optically almost transparent (extinction coefficient of 0.00 or less) in the wavelength range of about 660 nm and about 405 nm, but Cr ₂ O ₃ absorbs light in both wavelength ranges. It was opaque. The absorption of Cr ₂ O ₃ increased as the wavelength became shorter, and the extinction coefficient was near 0.3 near 405 nm. Therefore, for example, in the case of a mixed (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (mol%) composition, the extinction coefficient is about 0.02 in the wavelength range of about 660 nm, and in the about 405 nm range. It has an extinction coefficient of about 0.2. If it is not transparent, the dielectric layer itself absorbs light, leading to a decrease in light absorption of the recording layer and an increase in temperature of the dielectric layer itself. In phase change recording, an amorphous mark is formed by melting and quenching a laser beam irradiated portion in a recording layer (recording), and is crystallized by raising the temperature to a temperature higher than the crystallization temperature and gradually cooling (erasing). . When the light absorption of the recording layer is lowered, the recording sensitivity and erasing sensitivity of the recording layer are lowered (a laser beam irradiation with a higher power is required). Further, when the temperature of the dielectric layer itself is increased, the recording layer becomes difficult to be rapidly cooled during recording, and a good amorphous mark cannot be formed. As a result, the signal quality is degraded.

Regarding thermal conductivity, since it is difficult to accurately measure the thermal conductivity of a thin film, the magnitude of thermal conductivity is relatively compared based on the difference in recording sensitivity of individual information recording media. For example, if the thermal conductivity of the second dielectric layer is low, the heat is once accumulated in the recording layer and then quickly diffused toward the reflective layer without diffusing in the in-plane direction. That is, since the rapid cooling effect is increased, an amorphous mark can be formed with a smaller laser power (high recording sensitivity). On the contrary, if the thermal conductivity of the second dielectric layer is high, heat is not easily accumulated in the recording layer, and is easily diffused into the second dielectric layer. Then, the rapid cooling effect is small, and a large laser power is required for forming an amorphous mark (recording sensitivity is low). ZrO ₂ —SiO ₂ —Cr ₂ O ₃ has a higher thermal conductivity because a larger laser power is required for recording than when (ZnS) ₈₀ (SiO ₂ ) ₂₀ is used as the second dielectric layer. It was judged.

Thus, ZrO ₂ —SiO ₂ —Cr ₂ O ₃ has problems with respect to thermal conductivity and transparency. When applied to a DVD-RAM disc and a Blu-ray disc as the first or second dielectric layer, the recording sensitivity was low and improvement was required.

  The present invention solves the above-described conventional problems, and provides a dielectric material having low thermal conductivity and high transparency. Further, by applying this dielectric material, the conventional rewriting performance and moisture resistance can be improved. An object of the present invention is to provide an information recording medium having good recording sensitivity while maintaining it.

  A first information recording medium of the present invention is an information recording medium that enables at least one of information recording and reproduction by irradiation of light or application of electrical energy, and includes Zr, La, Ga, and In And an oxide material layer containing oxygen (O) and at least one element selected from the group GL1.

  The second information recording medium of the present invention is an information recording medium that enables at least one of recording and reproduction of information by light irradiation or application of electrical energy, and is M1 (where M1 is Zr And a mixture of Hf and Hf.), And an oxide-based material layer containing oxygen (O) and at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg, and Y It is characterized by including.

  A third information recording medium of the present invention is an information recording medium that enables at least one of recording and reproduction of information by light irradiation or application of electrical energy, and includes a group GM2 composed of Zr and Hf. An oxide-based material layer including at least one element selected, at least one element selected from the group GL2 including La, Ce, Al, Ga, In, Mg, and Y, Si, and oxygen (O). It is characterized by including.

  A fourth information recording medium of the present invention is an information recording medium that enables at least one of information recording and reproduction by irradiation of light or application of electrical energy, and includes a group GM2 composed of Zr and Hf. An oxide-based material layer including at least one element selected, at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg, and Y, Cr, and oxygen (O). It is characterized by including.

  A fifth information recording medium of the present invention is an information recording medium that enables at least one of information recording and reproduction by irradiation of light or application of electrical energy, and includes a group GM composed of Zr and Hf. Including an oxide material layer including at least one element selected, at least one element selected from the group GL consisting of La, Ce, Al, Ga, In, Mg, and Y, and oxygen (O). It is a feature.

  The first information recording medium manufacturing method of the present invention is an information including an oxide material layer containing Zr, at least one element selected from the group GL1 consisting of La, Ga and In, and oxygen (O). A method for manufacturing a recording medium, wherein the oxide material layer is formed by a sputtering method using a sputtering target containing Zr, at least one element selected from the group GL1, and oxygen (O). It is characterized by including a process.

  The second method for producing an information recording medium of the present invention comprises M1 (where M1 is a mixture of Zr and Hf or Hf), and a group consisting of La, Ce, Al, Ga, In, Mg, and Y. A method of manufacturing an information recording medium including an oxide-based material layer containing at least one element selected from GL2 and oxygen (O), wherein the oxide-based material layer is formed from M1 and the group GL2. The method includes a step of forming by a sputtering method using a sputtering target containing at least one selected element and oxygen (O).

  The third method for producing an information recording medium of the present invention is selected from at least one element selected from the group GM2 consisting of Zr and Hf and the group GL2 consisting of La, Ce, Al, Ga, In, Mg, and Y. A method for manufacturing an information recording medium including an oxide-based material layer containing at least one element, Si, and oxygen (O), wherein the oxide-based material layer is at least one selected from the group GM2. The method includes a step of forming by a sputtering method using a sputtering target including an element, at least one element selected from the group GL2, Si, and oxygen (O).

  The fourth method for producing an information recording medium of the present invention is selected from at least one element selected from the group GM2 consisting of Zr and Hf and the group GL2 consisting of La, Ce, Al, Ga, In, Mg, and Y. A method of manufacturing an information recording medium including an oxide material layer including at least one element, Cr, and oxygen (O), wherein the oxide material layer is at least one selected from the group GM2. The method includes a step of forming by a sputtering method using a sputtering target including an element, at least one element selected from the group GL2, Cr, and oxygen (O).

  The fifth method for producing an information recording medium of the present invention is selected from at least one element selected from the group GM consisting of Zr and Hf and the group GL consisting of La, Ce, Al, Ga, In, Mg, and Y. An information recording medium manufacturing method comprising an oxide material layer containing at least one element and oxygen (O), wherein the oxide material layer comprises at least one element selected from the group GM; The method includes a step of forming by a sputtering method using a sputtering target containing at least one element selected from the group GL and oxygen (O).

  The oxide-based material layer included in the information recording medium of the present invention has high transparency from the red wavelength region near 660 nm to the blue-violet wavelength region near 405 nm, and also has low thermal conductivity. Further, since this oxide-based material layer does not contain S, it can be provided in contact with the recording layer, and has sufficient thermal stability and moisture resistance at the same time. For this reason, for example, by applying this oxide-based material layer to the dielectric layer, an information recording medium capable of obtaining better recording sensitivity while ensuring sufficient reliability and excellent repeated rewriting performance is realized. Can do. In addition, in an information recording medium that uses electrical energy for recording or reproducing information, if this oxide material layer is used as a dielectric layer for insulating the recording layer, the phase of the recording layer can be reduced with a small electrical energy. Changes can be made. In addition, according to the method for producing an information recording medium of the present invention, an information recording medium having the above effects can be produced.

The first information recording medium of the present invention includes an oxide-based material layer containing Zr, at least one element selected from the group GL1 consisting of La, Ga, and In, and oxygen (O). This oxide-based material layer has a composition of Zr _Q1 L1 _T1 O _100-Q1-T1 (atomic%) (1)
(In the formula, L1 represents at least one element selected from the group GL1, and Q1 and T1 satisfy 0 <Q1 <34, 0 <T1 <50, 20 <Q1 + T1 <60). It is preferable to include a material. Furthermore, in the above formula (1), L1 is more preferably Ga.

  Here, “atomic%” means that the formula (1) is a compositional formula expressed based on the total number of “Zr” atoms, “L1” atoms, and “O” atoms (100%). Show. When L1 includes two or more elements, the total number of atoms of all the elements included is T1. In the following formulas, the expression “atomic%” is used for the same purpose. Further, the formula (1) is expressed by counting only “Zr” atoms, “L1” atoms, and “O” atoms contained in the oxide-based material layer. Therefore, the oxide material layer containing the material represented by the formula (1) may contain components other than these atoms.

  As described above, in Formula (1), Q1 and T1 preferably satisfy 0 <Q1 <34, 0 <T1 <50, and 20 <Q + T <60. When Zr is contained in an amount of 34 atomic% or more, the adhesion is deteriorated. If the element L1 is contained in an amount of 50 atomic% or more, the repeated rewrite performance deteriorates. Further, when oxygen (O) is less than 40 atomic%, the transparency is lowered. More preferably, 4 <Q1 <24, 6 <T1 <37, 30 <Q1 + T1 <50.

  In the formula (1), each atom may exist as any compound. The material is specified by such a formula because it is difficult to obtain the composition of the compound when examining the composition of the layer formed in the thin film. In reality, only the elemental composition (ie, the ratio of each atom) is determined. This is because there are many cases to ask for. In the material represented by the formula (1), it is considered that most of Zr and the element L1 exist as oxides together with oxygen atoms. Therefore, in this specification, even a layer containing a material represented by the formula (1) is referred to as an “oxide-based material layer” for convenience. The same applies to formulas (3), (5), (6), (9) and (10).

  In the oxide-based material layer included in the first information recording medium, assuming that most of Zr and element L1 are present as oxides together with oxygen atoms, the included material is expressed by the following formula (2). You can also.

(D1) _X1 (E1) _100-X1 (mol%) (2)
(Wherein D1 represents an oxide of Zr, E1 represents an oxide of at least one element selected from the group GL1, and X1 satisfies 0 <X1 <100.)
In the above formula (2), it is preferable that D1 is ZrO ₂ and E1 is Ga ₂ O ₃ .

The second information recording medium of the present invention is selected from M1 (where M1 is a mixture of Zr and Hf or Hf) and a group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y. An oxide-based material layer containing at least one element and oxygen (O). This oxide-based material layer has a composition of
M1 _Q2 L2 _T2 O _100-Q2-T2 (Atom%) (3)
(In the formula, M1 represents a mixture of Zr and Hf or Hf, L2 represents at least one element selected from the group GL2, and Q2 and T2 are 0 <Q2 <34, 0 <T2 <50, 20 <Q2 + T2 <60 is satisfied). Furthermore, in the above formula (3), L2 is more preferably Ga.

  Also in the second information recording medium of the present invention, “atomic%” is used in the same meaning as in the case of the first information recording medium, and when M1 is a mixture of Zr and Hf, When the total number of atoms of Zr and Hf is Q2, and L2 includes two or more elements, the total number of atoms of all the included elements is T2. Formula (3) represents only “M1” atoms, “L2” atoms, and “O” atoms included in the oxide-based material layer. Therefore, the oxide material layer containing the material represented by Formula (3) may contain components other than these atoms.

  As described above, in Formula (3), Q2 and T2 preferably satisfy 0 <Q2 <34, 0 <T2 <50, and 20 <Q2 + T2 <60. When the element M1 is contained in an amount of 34 atomic% or more, the adhesion is deteriorated. If the element L1 is contained in an amount of 50 atomic% or more, the repeated rewrite performance deteriorates. Further, when oxygen (O) is less than 40 atomic%, the transparency is lowered. More preferably, 4 <Q2 <24, 6 <T2 <37, 30 <Q2 + T2 <50.

  As in the case of the above formula (1), in the formula (3), each atom may exist as any compound. Even in the material represented by the formula (3), it is considered that most of the element M1 and the element L2 exist as oxides together with oxygen atoms. Therefore, when it is considered that most of the element M1 and the element L2 are present as oxides together with oxygen atoms, the material contained in the oxide-based material layer can also be expressed by the following formula (4).

(D2) _X2 (E2) _100-X2 (mol%) (4)
(Wherein D2 represents the oxide of M1, E2 represents an oxide of at least one element selected from the group GL2, and X2 satisfies 0 <X2 <100).
In the above formula (4), E2 is preferably Ga ₂ O ₃ .

The third information recording medium of the present invention includes at least one element selected from the group GM2 consisting of Zr and Hf, and at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y. An oxide-based material layer containing an element, Si, and oxygen (O) is included. This oxide-based material layer has a composition of
M2 _Q3 Si _R1 L2 _T3 O _100-Q3-R1-T3 (Atom%) (5)
(In the formula, M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and Q3, R1, and T3 are 0 <Q3 ≦ 32, 0 <R1. ≦ 32, 3 <T3 <43, 20 <Q3 + R1 + T3 <60 is satisfied).

In the third information recording medium of the present invention, the oxide material layer may further contain at least one element selected from the group GK1 consisting of carbon (C), nitrogen (N), and Cr. . In this case, the composition of the oxide-based material layer is
M2 _Q3 Si _R1 L2 _T3 K1 _J1 O _100-Q3-R1-T3 - _J1 (Atom%) (6)
(Wherein M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, K1 represents at least one element selected from the group GK1, Q3 , R1, T3, and J1 include a material represented by 0 <Q3 ≦ 32, 0 <R1 ≦ 35, 2 <T3 ≦ 40, 0 <J1 ≦ 40, 20 <Q3 + R1 + T3 + J1 <80. preferable.

In the above formula (5) and (6), M2 is Zr, and more preferably L2 is Ga _{(i.e., Zr Q3 Si R1 Ga T3 O} 100-Q3-R1-T3, Zr Q3 Si R1 Ga T3 K1 _J1 O _{100-Q3-R1-T3 —J1} is preferred).

  Also in the third information recording medium of the present invention, “atomic%” is used in the same meaning as in the first information recording medium, and when M2 contains two elements, When the total number of atoms of the element is Q3 and L2 includes two or more elements, the total number of atoms of all the included elements is T3, and K1 includes two or more elements In this case, the total number of atoms of all the contained elements is J1. Further, the formula (5) is expressed by counting only “M2” atoms, “L2” atoms, “Si” atoms, and “O” atoms contained in the oxide-based material layer, and the formula (6) is , Only “M2” atoms, “L2” atoms, “Si” atoms, “K1” atoms, and “O” atoms included in the oxide-based material layer are counted. Therefore, the oxide material layer containing the material represented by formula (5) or (6) may contain components other than these atoms.

  As described above, in the formula (5), Q3, R1 and T3 preferably satisfy 0 <Q3 ≦ 32, 0 <R1 ≦ 32, 3 <T3 <43, 20 <Q3 + R1 + T3 <60. When the element M2 or Si is contained in an amount of more than 32 atomic%, the adhesion is deteriorated. When the element L2 is contained in 43 atomic% or more, the repeated rewrite performance deteriorates. Further, when oxygen (O) is less than 40 atomic%, the transparency is lowered. More preferably, 0 <Q3 <25, 0 <R1 <25, 6 <T3 <37, 30 <Q3 + R1 + T3 <50. Therefore, this oxide material is a material excellent in thermal stability, high transparency, adhesion, moisture resistance, and low thermal conductivity.

  As in the case of the above formula (1), in the formulas (5) and (6), each atom may exist as any compound. For example, in the material represented by the formula (5), it is considered that most of the elements M2, Si, and the element L2 exist as oxides together with oxygen atoms. Si may be contained as a nitride or carbide. Therefore, the material represented by the above formula (5) or (6) contained in the oxide-based material layer can also be represented by the following formula (7) or (8).

(D3) _X3 (g) _Z1 (E2) _100-X3-Z1 (mol%) (7)
Wherein D3 represents an oxide of at least one element selected from the group GM2, g represents at least one compound selected from the group consisting of SiO ₂ , Si ₃ N ₄ and SiC, and E2 represents the group An oxide of at least one element selected from GL2 is shown, and X3 and Z1 satisfy 10 ≦ X3 <90, 0 <Z1 ≦ 50, and 10 <X3 + Z1 ≦ 90.)
_{(D3) X3 (SiO 2)} Z2 (f) A1 (E2) 100-X3 - Z2-A1 (mol%) (8)
(Wherein D3 and E2 represent the same oxide as in the above formula (7), f represents at least one compound selected from the group consisting of SiC, Si ₃ N ₄ and Cr ₂ O ₃ ; , Z2 and A1 satisfy 10 ≦ X3 <90, 0 <Z2 ≦ 50, 0 <A1 ≦ 50, 10 <X3 + Z2 + A1 ≦ 90.)
In the above formulas (7) and (8), it is preferable that D3 is ZrO ₂ and E2 is Ga ₂ O ₃ .

The fourth information recording medium of the present invention includes at least one element selected from the group GM2 consisting of Zr and Hf, and at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y. An oxide-based material layer containing an element, Cr, and oxygen (O) is included. This oxide-based material layer has a composition of
M2 _Q4 Cr _U L2 _T4 O _100-Q4-U-T4 (Atom%) (9)
(In the formula, M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and Q4, U, and T4 are 0 <Q4 ≦ 32, 0 <U ≦ 25, 0 <T4 ≦ 40, 20 <Q4 + U + T4 <60 is satisfied).

In the fourth information recording medium of the present invention, the oxide material layer may contain at least one element selected from the group GK2 consisting of nitrogen (N) and carbon (C). In this case, the composition of the oxide-based material layer is
M2 _Q4 Cr _U L2 _T4 Si _R2 K2 _J2 O _{100-Q4-U-T4-R2-J2} (Atom%) ・ ・ （10）
(In the formula, M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and K2 represents a group GK2 composed of nitrogen (N) and carbon (C)). At least one element selected, Q4, U, T4, R2 and J2 are 0 <Q4 ≦ 32, 0 <U ≦ 25, 0 <T4 ≦ 40, 0 <R2 ≦ 30, 0 <J2 ≦ 40, 25 <Q4 + U + T4 + R2 + J2 <85 is satisfied).

In the above formula (9) and (10), M2 is Zr, it is preferable L2 is Ga _{(i.e., Zr Q4 Cr U Ga T4 O} 100-Q4-U-T4, Zr Q4 Cr U Ga _{T4 Si R2 K2 J2 O 100-} Q4-U-T4-R2-J2 are preferable.).

  In the formula (10), Q4, U, T4, R2 and J2 are 0 <Q4 ≦ 32, 0 <U ≦ 25, 0 <T4 ≦ 40, 0 <R2 ≦ 30, 0 <J2 ≦ 40, 25 <Q4 + U + T4 + R2 + J2 It is preferable to satisfy <85. In the material system represented by the formula (10), the heat resistance is improved by the inclusion of the element M2, but if the content exceeds 32 atomic%, the adhesion with the recording layer is lowered. The content is preferably 32 atomic% or less. Further, when Cr is contained in this material system, the adhesion to the recording layer is improved. However, when C and N are contained, the Cr content should be 25 atomic% or less so as not to lower the transparency. Is preferred. Further, when the element L2 is contained in this material system, the transparency of the oxide material layer is improved, but the content is preferably 40 atomic% or less so as not to reduce the rewrite performance repeatedly. Further, when Si is mixed with oxides as nitrides and carbides, the structure becomes complicated and the thermal conductivity of this material system can be lowered. However, in this material system, it is preferable that the Si content is 30 atomic% or less so as not to lower the adhesion to the recording layer. In addition, since the element K2 (C, N) easily forms a compound with Si in this material system, the thermal conductivity can be lowered for the above-described reason. However, in order not to lower the transparency, the inclusion of C The amount is preferably 20 atomic% or less, and the N content is preferably 40 atomic% or less. Further, in this material system, when a large amount of N is contained, transparency can be obtained even if O is small as compared with other material systems. However, when O is 15 atomic% or less, the transparency is lowered, and when it is 75 atomic% or more, O is excessive, and it becomes easier to bond to Si than C and N, making it difficult to adjust the thermal conductivity. Accordingly, O is preferably more than 15 atomic% and less than 75 atomic%.

  As in the case of the above formula (1), in the formulas (9) and (10), each atom may exist as any compound. For example, in the material represented by the formula (9), it is considered that most of the elements M2, Cr and element L2 exist as oxides together with oxygen atoms. Further, in the material represented by the above formula (10), Si is considered to exist as at least one of oxide, nitride, and carbide. Therefore, the material represented by the above formula (9) or (10) included in the oxide-based material layer can also be represented by the following formula (11) or (12).

(D3) _X4 (Cr ₂ O ₃ ) _A2 (E2) _100-X4-A2 (mol%) (11)
(Wherein D3 represents an oxide of at least one element selected from the group GM2, E2 represents an oxide of at least one element selected from the group GL2, and X4 and A2 are 10 ≦ X4 <90. 0 <A2 ≦ 40, 10 <X4 + A2 ≦ 90 is satisfied.)
_{(D3) X4 (Cr 2 O} 3) A2 (h) Z3 (E2) 100-X4-A2-Z3 (mol%) (12)
(Wherein D3 represents an oxide of at least one element selected from the group GM2, h represents at least one compound selected from the group consisting of Si ₃ N ₄ and SiC, and E2 is selected from the group GL2. X4 and A2 and Z3 satisfy the following conditions: 10 ≦ X4 <90, 0 <A2 ≦ 40, 0 <Z3 ≦ 40, 10 <X4 + A2 + Z3 ≦ 90)
In the material system represented by the above formulas (11) and (12), the heat resistance is improved by including D3. However, if the content exceeds 90 mol%, the adhesiveness with the recording layer is reduced. 90 mol% or less is preferable. Further, in this material system, the adhesion to the recording layer is improved by containing Cr ₂ O _3, but the content is preferably 40 mol% or less in order to suppress a decrease in transparency. Further, in this material system, the transparency is improved by including E2, but the content is preferably less than 90 mol% in order to suppress a decrease in rewrite performance. In addition, according to h included in the material system represented by the above formula (12), the structure becomes complicated, so that the thermal conductivity of the material system can be lowered. However, in this material system, the h content is preferably 40 mol% or less in order to suppress a decrease in transparency.

In the above formulas (11) and (12), it is preferable that D3 is ZrO ₂ and E2 is Ga ₂ O ₃ .

The oxides of Zr and Hf are both transparent, have a high melting point, and are excellent in thermal stability. It is considered that each of them is present in the oxide-based material layer as approximately ZrO ₂ and HfO ₂ . In an information recording medium provided with a layer containing such a material having excellent thermal stability, even when information is repeatedly rewritten, it is hardly deteriorated and has excellent durability. ZrO ₂ and HfO ₂ exhibit almost the same properties, but ZrO ₂ is more practical because it is less expensive. Furthermore, when Si is included, flexibility is obtained in addition to thermal stability. For this reason, it becomes strong against the expansion and contraction of the film at the time of rewriting repeatedly, and the film is hardly broken. Si oxide is also excellent in transparency.

The oxides of La, Ce, Al, Ga, In, Mg, and Y are all transparent near the laser wavelength of 405 nm and have an extinction coefficient of approximately 0.00. It is considered that La ₂ O ₃ , CeO ₂ , Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , MgO and Y ₂ O ₃ are present in the oxide-based material layer, respectively. These oxides are insoluble in water and exhibit excellent moisture resistance. Further, it adheres well to the recording layer which is a chalcogenide material. Among these, Ga ₂ O ₃ is rich in transparency and adhesion. Furthermore, compared with Cr ₂ O ₃ , it has a low thermal conductivity and a high film formation rate, so that it is a material with excellent practicality.

  The first to fourth information recording media of the present invention may further include a recording layer, and the recording layer may be formed of a phase change material that causes an amorphous and crystalline phase transformation. The phase change material used may be a write-once material that causes irreversible phase transformation or a rewritable material that causes reversible phase transformation. Specifically, the rewritable materials include Ge—Sb—Te, Ge—Sn—Sb—Te, Ge—Bi—Te, Ge—Sn—Bi—Te, Ge—Sb—Bi—Te, Ge—Sn—. Any one material selected from Sb-Bi-Te, Ag-In-Sb-Te, and Sb-Te is included. The thickness of the recording layer is preferably 20 nm or less, more preferably 3 nm to 15 nm. Alternatively, even a magneto-optical material such as Tb—Fe—Co, Gd—Tb—Fe—Co, Tb—Fe, Dy—Fe—Co, or Dy—Nd—Fe—Co that utilizes magnetization reversal. Good. A plurality of recording layers including such a recording layer (other types of recording layers may be included) may be provided. The oxide-based material layer can be applied regardless of the type or number of recording layers, and in addition to a medium for recording by optical means such as laser light, a medium for recording by electric means. Can also be applied.

  The oxide material layer may be disposed in contact with at least one surface of the recording layer. Since the oxide-based material layer does not contain S, even if it is formed in direct contact with the recording layer, an information recording medium having good repeated rewriting performance and moisture resistance can be obtained.

  Next, the manufacturing method of the 1st-4th information recording medium of this invention is demonstrated.

  Each of the first to fourth information recording medium manufacturing methods of the present invention is a method including a step of forming an oxide-based material layer by a sputtering method. According to the sputtering method, an oxide-based material layer having substantially the same composition as the sputtering target can be formed. Therefore, according to this manufacturing method, an oxide material layer having a desired composition can be easily formed by appropriately selecting a sputtering target.

The first information recording medium manufacturing method of the present invention is an information including an oxide-based material layer containing Zr, at least one element selected from the group GL1 consisting of La, Ga and In, and oxygen (O). A method for manufacturing a recording medium, wherein the oxide material layer is formed by a sputtering method using a sputtering target containing Zr, at least one element selected from the group GL1, and oxygen (O). Process. In this case, the sputtering target has the following composition:
Zr _q1 L1 _t1 O _100-q1-t1 (atomic%) (13)
(In the formula, L1 represents at least one element selected from the group GL1, and q1 and t1 satisfy 0 <q1 <34, 0 <t1 <50, and 20 <q1 + t1 <60). It is preferable to include a material. In Formula (13), it is more preferable that L1 is Ga.

  The composition of this sputtering target can also be expressed by the following formula (14), considering that Zr and the element L1 exist as oxides.

(D1) _x1 (E1) _100-x1 (mol%) (14)
(Wherein D1 represents an oxide of Zr, E1 represents an oxide of at least one element selected from the group GL1, and x1 satisfies 0 <x1 <100 (preferably 20 ≦ x1 ≦ 80). .)
By sputtering the sputtering target represented by the formula (14), an oxide-based material layer including the material represented by the formula (1) can be formed. According to the experiments by the present inventors, the element composition (atomic%) of the formed oxide-based material layer is compared with the element composition (atomic%) calculated from the display composition (mol%) of the sputtering target. It was confirmed that the amount of oxygen may be small from 1 atomic% to 2 atomic%.

In the above formula (14), it is preferable that D1 is ZrO ₂ and E1 is Ga ₂ O ₃ (that is, in formula (14), (ZrO ₂ ) _x1 (Ga ₂ O ₃ ) _100-x1 ( mol%) sputtering target.).

  When D1 includes two oxides, the total number of moles of the two oxides is x1, and similarly, when E1 includes two or more oxides, all the oxides included The total number of moles is (100−x).

  Thus, the sputtering target is specified because the sputtering target containing Zr, an element selected from group GL1 and oxygen (O) is usually a composition of an oxide of Zr and an oxide of an element selected from group GL1. Is displayed and supplied. In addition, it is difficult to directly mix a low melting point material such as Ga or In and a high melting point material such as Zr in the manufacturing process of the sputtering target. The method to do is common.

  In addition, the present inventors have found that the elemental composition obtained by analyzing the sputtering target whose composition is so displayed with an X-ray microanalyzer is substantially equal to the elemental composition calculated from the displayed composition. (That is, the composition display (nominal composition) is appropriate). Accordingly, the sputtering target provided as a mixture of oxides is also preferably used in the first method for producing an information recording medium of the present invention. The same applies to the second to fourth information recording medium manufacturing methods described below.

The second method for producing an information recording medium of the present invention comprises M1 (where M1 is a mixture of Zr and Hf or Hf), and a group consisting of La, Ce, Al, Ga, In, Mg, and Y. A method of manufacturing an information recording medium including an oxide-based material layer containing at least one element selected from GL2 and oxygen (O), wherein the oxide-based material layer is formed from M1 and the group GL2. The method includes a step of forming by a sputtering method using a sputtering target containing at least one selected element and oxygen (O). In this case, the sputtering target has the following composition:
M1 _q2 L2 _t2 O _100-q2-t2 (atomic%) (15)
(Wherein, M1 represents a mixture of Zr and Hf or Hf, L2 represents at least one element selected from the group GL2, q2 and t2 are 0 <q2 <34, 0 <t2 <50, 20 <q2 + t2 <60 is preferably satisfied). In Formula (15), it is more preferable that L2 is Ga.

  The composition of this sputtering target can also be expressed by the following formula (16), considering that the elements M1 and L2 exist as oxides.

(D2) _x2 (E2) _100-x2 (mol%) (16)
(Wherein D2 represents the oxide of M1, E2 represents an oxide of at least one element selected from the group GL2, and x2 represents 0 <x2 <100 (preferably 20 ≦ x2 ≦ 80). Fulfill.)
By sputtering the sputtering target represented by formula (16), an oxide-based material layer containing the material represented by formula (3) can be formed. According to the experiments by the present inventors, the element composition (atomic%) of the formed oxide-based material layer is compared with the element composition (atomic%) calculated from the display composition (mol%) of the sputtering target. It was confirmed that the amount of oxygen may be small from 1 atomic% to 2 atomic%.

In the above formula (16), E2 is preferably Ga ₂ O ₃ .

The third method for producing an information recording medium of the present invention is selected from at least one element selected from the group GM2 consisting of Zr and Hf and the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y. A method of manufacturing an information recording medium including an oxide material layer including at least one element, Si, and oxygen (O), wherein the oxide material layer is at least one selected from the group GM2. A step of forming by a sputtering method using a sputtering target including an element, at least one element selected from the group GL2, Si, and oxygen (O). In this case, the sputtering target has the following composition:
M2 _q3 Si _r1 L2 _t3 O _100-q3-r1-t3 (atomic%) (17)
(In the formula, M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and q3, r1, and t3 are 0 <q3 ≦ 32, 0 <r1. ≦ 32, 3 <t3 <43, 20 <q3 + r1 + t3 <60).

Further, in the manufacturing method of the third information recording medium of the present invention, the sputtering target further carbon (C), also comprise at least one element selected from the group GK 1 consisting of nitrogen (N) and Cr Good. In this case, the sputtering target has the following composition:
M2 _q3 Si _r1 L2 _t3 K1 _j1 O _{100-q3-r1-t3-j1} (atomic%) (18)
(Wherein M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, K1 represents at least one element selected from the group GK1, q3 , R1, t3, and j1 include a material represented by 0 <q3 ≦ 32, 0 <r1 ≦ 35, 2 <t3 ≦ 40, 0 <j1 ≦ 40, 20 <q3 + r1 + t3 + j1 <80). preferable.

  In the formulas (17) and (18), it is more preferable that M2 is Zr and L2 is Ga.

  The composition of the sputtering target shown in the above formula (17) is based on the following formula (19), considering that M2 and L2 are present as oxides and Si is present as at least one of oxides, nitrides and carbides. ).

(D3) _x3 (g) _z1 (E2) _100-x3-z1 (mol%) (19)
Wherein D3 represents an oxide of at least one element selected from the group GM2, g represents at least one compound selected from the group consisting of SiO ₂ , Si ₃ N ₄ and SiC, and E2 represents the group An oxide of at least one element selected from GL2, wherein x3 and z1 are 10 ≦ x3 <90 (preferably 10 ≦ x3 <70), 0 <z1 ≦ 50 (preferably 0 <z1 ≦ 50), 10 <X3 + z1 ≦ 90 (preferably satisfies 20 ≦ x3 + z1 ≦ 80).
By sputtering the sputtering target represented by formula (19), an oxide-based material layer including the material represented by formula (5) can be formed. According to the experiments by the present inventors, the element composition (atomic%) of the formed oxide-based material layer is compared with the element composition (atomic%) calculated from the display composition (mol%) of the sputtering target. It was confirmed that the amount of oxygen may be small from 1 atomic% to 2 atomic%.

  The composition of the sputtering target shown in the above formula (18) can also be expressed by the following formula (20).

_{(D3) x3 (SiO 2)} z2 (f) a1 (E2) 100-x3 - z2-a1 (mol%) (20)
(Wherein D3 represents an oxide of at least one element selected from the group GM2, f represents at least one compound selected from the group consisting of SiC, Si ₃ N ₄ and Cr ₂ O ₃ , and E2 represents An oxide of at least one element selected from the group GL2, wherein x3, z2, and a1 satisfy 10 ≦ x3 <90, 0 <z2 ≦ 50, 0 <a1 ≦ 50, and 10 <x3 + z2 + a1 ≦ 90.
By sputtering the sputtering target represented by formula (19), an oxide-based material layer containing the material represented by formula (6) can be formed. According to the experiments by the present inventors, the element composition (atomic%) of the formed oxide-based material layer is compared with the element composition (atomic%) calculated from the display composition (mol%) of the sputtering target. It was confirmed that the amount of oxygen may be small from 1 atomic% to 2 atomic%.

In the above formulas (19) and (20), it is preferable that D3 is ZrO ₂ and E2 is Ga ₂ O ₃ (that is, for example, in formula (19), (ZrO ₂ ) _x3 (SiO ₂ ) _z1 (Ga ₂ O ₃ ) _100-x3-z1 (mol%) sputtering target.).

The fourth method for producing an information recording medium of the present invention is selected from at least one element selected from the group GM2 consisting of Zr and Hf and the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y. A method of manufacturing an information recording medium including an oxide material layer containing at least one element, Cr, and oxygen (O), wherein the oxide material layer is at least one selected from the group GM2. A step of forming by a sputtering method using a sputtering target including an element, at least one element selected from the group GL2, Cr, and oxygen (O). In this case, the sputtering target has the following composition:
_{M2 q4 Cr u L2 t4 O 100} -q4-u-t4 ( atom%) (21)
(In the formula, M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and q4, u, and t4 are 0 <q4 ≦ 32, 0 <u. ≦ 25, 0 <t4 ≦ 40, 20 <q4 + u + t4 <60 is satisfied).

Further, the sputtering target used in the fourth information recording medium of the present invention may contain at least one element selected from the group GK2 consisting of nitrogen (N) and carbon (C). In this case, the sputtering target has the following composition:
M2 _q4 Cr _u L2 _t4 Si _r2 K2 _j2 O _{100-q4-u-t4-r2-j2} (Atom%) (22)
(In the formula, M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and K2 represents a group GK2 composed of nitrogen (N) and carbon (C)). At least one element selected, q4, u, t4, r2 and j2 are 0 <q4 ≦ 32, 0 <u ≦ 25, 0 <t4 ≦ 40, 0 <r2 ≦ 30, 0 <j2 ≦ 40, 25 <q4 + u + t4 + r2 + j2 <85 is preferably satisfied).

  In the above formulas (21) and (22), it is preferable that M2 is Zr and L2 is Ga.

  The sputtering target containing the material represented by the above formulas (21) and (22) can also be represented by the following formula (23) or (24), respectively.

(D3) _x4 (Cr ₂ O ₃ ) _a2 (E2) _100-x4-a2 (mol%) (23)
(Wherein D3 represents an oxide of at least one element selected from the group GM2, E2 represents an oxide of at least one element selected from the group GL2, and x4 and a2 are 10 ≦ x4 <90. 0 <a2 ≦ 40, 10 <x4 + a2 ≦ 90 is satisfied.)
_{(D3) x4 (Cr 2 O} 3) a2 (h) z3 (E2) 100-x4-a2-z3 (mol%) (24)
(Wherein D3 represents an oxide of at least one element selected from the group GM2, h represents at least one compound selected from the group consisting of Si ₃ N ₄ and SiC, and E2 is selected from the group GL2) X4 and a2 and z3 satisfy the following conditions: 10 ≦ x4 <90, 0 <a2 ≦ 40, 0 <z3 ≦ 40, 10 <x4 + a2 + z3 ≦ 90)
In the above formulas (22) and (23), it is preferable that D3 is ZrO ₂ and E2 is Ga ₂ O ₃ .

For example, in the above formula (19), in the case of a sputtering target in which D3 is ZrO ₂ , g is SiO ₂ , and x3 = z1, a composite of ZrSiO ₄ containing ZrO ₂ and SiO ₂ at substantially equal ratios. An oxide may be included. In addition, the material represented by any of the above formulas (2), (4), (14), (16) and (19) is CeZrO ₄ , Hf ₂ La ₂ O ₇ , LaAlO ₃ , LaGaO ₃ , Mg A composite oxide such as ₂ SiO ₄ , MgSiO ₃ , MgZrO ₃ , Y ₃ Al ₅ O ₁₂ , Y ₃ Ga ₅ O ₁₂ , Y _0.15 Zr _0.85 O _1.93 and ZrSiO ₄ may be included. For example, a composite oxide may be formed from two or more oxides such that MgSiO ₃ exists as a composite oxide of MgO and SiO ₂ and ZrSiO ₄ exists as a composite oxide of ZrO ₂ and SiO _2. Good thermal stability is obtained.

  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 that records and reproduces information using laser light will be described. FIG. 1 shows a partial cross section of the optical information recording medium.

  The information recording medium 25 shown in FIG. 1 has a first dielectric layer 2, a recording layer 4, a second dielectric layer 6, a light absorption correction layer 7, and a reflective layer 8 in this order on one surface of the substrate 1. In addition, the dummy substrate 10 is bonded to the reflective layer 8 with the adhesive layer 9. That is, the reflective layer 8 is formed on the light absorption correction layer 7, the light absorption correction layer 7 is formed on the second dielectric layer 6, and the second dielectric layer 6 is formed on the recording layer 4. The recording layer 4 is formed on the first dielectric layer 2. The information recording medium having this configuration can be used as a 4.7 GB / DVD-RAM that records and reproduces information with a red laser beam having a wavelength of around 660 nm. The laser beam 12 is incident on the information recording medium 25 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. 12 in that it does not have the first interface layer 103 and the second interface layer 105.

  In the first embodiment, both the first dielectric layer 2 and the second dielectric layer 6 are oxide material layers. As described above, the oxide material layer is one of the following four.

(I) An oxide-based material layer (II) M1 containing Zr, at least one element selected from the group GL1 consisting of La, Ga, and In, and oxygen (O) (where M1 is composed of Zr and Hf) And an oxide-based material layer (III) containing oxygen (O) and at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y) At least one element selected from the group GM2 consisting of Zr and Hf, at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y, Si, oxygen (O), And at least one element selected from the group GM2 consisting of Zr and Hf, and at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y When And Cr, the oxide-based material layer containing oxygen (O)

In general, the material of the dielectric layer is required to be transparent, have a high melting point, do not melt during recording, and have good adhesion to the recording layer, which is a chalcogenide material. Being transparent is a characteristic necessary for allowing the laser beam 12 incident from the substrate 1 side to pass and reach the recording layer 4. This characteristic is particularly required for the first dielectric layer on the incident side. A high melting point is a characteristic necessary to ensure that the material of the dielectric layer is not mixed into the recording layer when irradiated with laser light having a peak power level, and both the first and second dielectric layers are used. Is required. When the material of the dielectric layer is mixed in the recording layer, the repeated rewriting performance is remarkably lowered. Good adhesion to the recording layer, which is a chalcogenide material, is a characteristic necessary for ensuring the reliability of the information recording medium, and is required for both the first and second dielectric layers. Furthermore, the material of the dielectric layer is such that the obtained information recording medium is a conventional information recording medium (that is, an interface between the dielectric layer made of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) and the recording layer. The recording sensitivity should be equal to or higher than that of the medium on which the layer is located.

Of the components contained in the oxide-based material layers (I) to (IV), each of the oxides of Zr and Hf is transparent, has a high melting point, and is excellent in thermal stability. Therefore, according to these compounds, the repeated rewritability of the information recording medium can be ensured. Of the components contained in the oxide-based material layers (I) to (IV), the oxides of La, Ce, Al, Ga, In, Mg, and Y are also transparent and are in close contact with the recording layer. Excellent in moisture and moisture resistance. Therefore, according to these compounds, the moisture resistance of the information recording medium can be ensured. The oxides of Zr and Hf include, for example, ZrO ₂ and HfO ₂ , respectively. Examples of the oxides of La, Ce, Al, Ga, In, Mg, and Y include La ₂ O ₃ , CeO ₂ , Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , MgO, and Y _2. Each of O ₃ is included. Further, SiO ₂ may be included. The melting points of these oxides are (literature values): ZrO ₂ and HfO ₂ are about 2700 ° C., La ₂ O ₃ is about 2300 ° C., CeO ₂ is about 2000 ° C., Al ₂ O ₃ is about 2000 ° C., Ga ₂ O ₃ is about 1700 ° C., In ₂ O ₃ is about 1900 ° C., MgO is about 2800 ° C., Y ₂ O ₃ is about 2400 ° C., and SiO ₂ is about 1700 ° C. In any case, the melting point of the recording layer is sufficiently higher than 500 to 700 ° C., and the possibility of melting and diffusing into the recording layer during recording is extremely low. In addition, a composite oxide may be formed including oxides of these two or more elements. For example, ZrSiO ₄ containing ZrO ₂ and SiO ₂ in a substantially equal proportion, and MgSiO ₃ containing MgO and SiO ₂ in a substantially equal proportion may be formed.

  The layer containing the material mixed with these oxides is used as the first dielectric layer 2 and the second dielectric layer 6 and is formed so as to be in contact with the recording layer 4 as shown in the figure, thereby repeatedly rewriting. An information recording medium 25 having excellent performance and good adhesion between the recording layer and the dielectric layer can be realized.

When the oxide-based material layer (I) is used as the dielectric layers 2 and 6, this oxide-based material layer is made of Zr _Q1 L1 _T1 O _100-Q1-T1 (atomic%) (wherein L1 is At least one element selected from the group GL1, wherein Q1 and T1 include a material represented by 0 <Q1 <34, 0 <T1 <50, and 20 <Q1 + T1 <60). When Zr is contained in an amount of 34 atomic% or more, the adhesion is deteriorated. If the element L1 is contained in an amount of 50 atomic% or more, the repeated rewrite performance deteriorates. Moreover, if oxygen (O) is less than 40 atomic%, the transparency is lowered. More preferably, 4 <Q1 <24, 6 <T1 <37, 30 <Q1 + T1 <50.

When the oxide-based material layer (II) is used as the dielectric layers 2 and 6, this oxide-based material layer is M1 _Q2 L2 _T2 O _100-Q2-T2 (atomic%) (wherein M1 Represents a mixture of Zr and Hf or Hf, L2 represents at least one element selected from the group GL2, and Q2 and T2 are 0 <Q2 <34, 0 <T2 <50, 20 <Q2 + T2 <60 The material represented by the above is included. When M1 is contained in an amount of 34 atomic% or more, the adhesion is deteriorated. When the element L2 is contained in an amount of 50 atomic% or more, the repeated rewriting performance is deteriorated. Moreover, if oxygen (O) is less than 40 atomic%, the transparency is lowered. More preferably, 4 <Q2 <24, 6 <T2 <37, 30 <Q2 + T2 <50.

Examples of the component elements of the oxide-based material layers (I) and (II) include Zr—La—O, Zr—Hf—La—O, Hf—La—O, Zr—Hf—Ce—O, Hf—Ce—O, Zr—Hf—Al—O, Hf—Al—O, Zr—Ga—O, Zr—Hf—Ga—O, Hf—Ga—O, Zr—In—O, Zr—Hf— In-O, Hf-In-O, Zr-Hf-Mg-O, Hf-Mg-O, Zr-Hf-Y-O, Hf-Y-O, etc., all of which are two or more oxides It is considered to be present in the layer in a mixed form. When the composition of the oxide-based material layer is analyzed with an X-ray microanalyzer or the like, atomic% (Q1, T1, 100-Q1-T1, Q2, T2, 100-Q2-T2) of each element is obtained. For example, in the case of Zr—Ga—O, it is considered that it is almost present as ZrO ₂ —Ga ₂ O ₃ . Zr—Ga—O is an excellent material having high transparency, low thermal conductivity, high adhesion, and a high film formation rate.

It is considered that other materials other than Zr—Ga—O exist as mixed materials as follows. _{ZrO 2 -La 2 O 3, ZrO} 2 -HfO 2 -La 2 O 3, HfO 2 -La 2 O 3, ZrO 2 -HfO 2 -CeO 2, HfO 2 -CeO 2, ZrO 2 -HfO 2 -Al 2 O ₃ , HfO ₂ —Al ₂ O ₃ , ZrO ₂ —Ga ₂ O ₃ , ZrO ₂ —HfO ₂ —Ga ₂ O ₃ , HfO ₂ —Ga ₂ O ₃ , ZrO ₂ —In ₂ O ₃ , ZrO ₂ —HfO _{2 -In 2 O 3, HfO 2} -In 2 O 3, ZrO 2 -HfO 2 -MgO, HfO 2 -MgO, etc. _{ZrO 2 -HfO 2 -Y 2 O 3} , HfO 2 -Y 2 O 3 and the like .

When using the oxide-based material layer of the (III) as the dielectric layers 2 and 6, the oxide-based material _{layer, M2 Q3 Si R1 L2 T3 O} 100-Q3-R1-T3 ( atom%) (wherein , M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and Q3, R1 and T3 are 0 <Q3 ≦ 32, 0 <R1 ≦ 32, 3 <T3 <43, 20 <Q3 + R1 + T3 <60). When the element M2 or Si is contained in an amount of more than 32 atomic%, the adhesion is deteriorated. When the element L2 is contained in 43 atomic% or more, the repeated rewriting performance deteriorates. Moreover, if oxygen (O) is less than 40 atomic%, the transparency is lowered. More preferably, 0 <Q3 <25, 0 <R1 <25, 6 <T3 <37, 30 <Q3 + R1 + T3 <50.

Examples of the component elements of the oxide-based material layer (III) include Zr—Si—La—O, Zr—Si—Hf—La—O, Hf—Si—La—O, and Zr—Si—Ce—. O, Zr-Si-Hf-Ce-O, Hf-Si-Ce-O, Zr-Si-Al-O, Zr-Si-Hf-Al-O, Hf-Si-Al-O, Zr-Si- Ga-O, Zr-Si-Hf-Ga-O, Hf-Si-Ga-O, Zr-Si-In-O, Zr-Si-Hf-In-O, Hf-Si-In-O, Zr- Si-Mg-O, Zr-Si-Hf-Mg-O, Hf-Si-Mg-O, Zr-Si-Y-O, Zr-Hf-Si-YO, Hf-Si-YO, Zr—Si—Ga—Y—O and the like are all considered to be present in the layer in the form of a mixture of two or more oxides. For example, in the case of Zr—Si—Ga—O, it is considered that ZrO ₂ —SiO ₂ —Ga ₂ O ₃ is present. In particular, Zr—Si—Ga—O is an excellent material having high transparency, low thermal conductivity, high adhesion, high rewrite performance, and high film formation rate.

It is considered that other materials other than Zr—Si—Ga—O exist as mixed materials as follows. ZrO ₂ —SiO ₂ —La ₂ O ₃ , ZrO ₂ —HfO ₂ —SiO ₂ —La ₂ O ₃ , HfO ₂ —SiO ₂ —La ₂ O ₃ , ZrO ₂ —SiO ₂ —CeO ₂ , ZrO ₂ —HfO _{2 -SiO 2 -CeO 2, HfO 2 -SiO} 2 -CeO 2, ZrO 2 -SiO 2 -Al 2 O 3, ZrO 2 -HfO 2 -SiO 2 -Al 2 O 3, HfO 2 -SiO 2 -Al 2 O ₃ , ZrO ₂ —SiO ₂ —Ga ₂ O ₃ , ZrO ₂ —HfO ₂ —SiO ₂ —Ga ₂ O ₃ , HfO ₂ —SiO ₂ —Ga ₂ O ₃ , ZrO ₂ —SiO ₂ —In ₂ O ₃ , ZrO _{2 -HfO 2 -SiO 2 -In 2 O} 3, HfO 2 -SiO 2 -In 2 O 3, ZrO 2 -SiO 2 -MgO (ZrO 2 -MgSiO 3), ZrO 2 -HfO 2 -SiO 2 -MgO, HfO ₂ —SiO ₂ —MgO, ZrO ₂ —SiO ₂ —Y ₂ O ₃ , ZrO ₂ —HfO ₂ —SiO ₂ —Y ₂ O ₃ , HfO ₂ —SiO ₂ —Y ₂ O ₃ , ZrO ₂ —SiO ₂ —Ga ₂ O ₃ —Y ₂ O _{3 and the} like.

The oxide material layer (III) may further contain at least one element K1 selected from the group GK1 consisting of C, N, and Cr. The oxide-based material _{layer, M2 Q3 Si R1 L2 T3 K1} J1 O 100-Q3-R1-T3-J1 ( atom%) (wherein, M2 represents at least one element selected from the group GM2, L2 Represents at least one element selected from the group GL2, K1 represents at least one element selected from the group GK1, Q3, R1, T3 and J1 are 0 <Q3 ≦ 32, 0 <R1 ≦ 35, 2 <T3 ≦ 40, 0 <J1 ≦ 40, 20 <Q3 + R1 + T3 + J1 <80 is satisfied). When the element M2 and the oxide of Si are included, the rewriting performance is repeatedly improved, and the Si oxide also has a function of improving transparency. Further, the oxide of the element L2 has high transparency and excellent adhesion to the recording layer. Furthermore, by including the element K1, it is possible to obtain the effects of reducing the thermal conductivity of the oxide-based material layer and further improving the adhesion with the recording layer. Specifically, when the element K1 is C, a carbide of Si is present together with oxides of the elements M2 and L2, and it is expected that a complicated structure is formed without being mixed with each other. Similarly, when the element K1 is N, the nitride of Si is present together with the oxides of the elements M2 and L2, and it is expected that a complicated structure is formed without being mixed with each other. It is considered that heat becomes difficult to be transmitted due to the complicated structure, and the thermal conductivity can be reduced. Further, the Cr oxide included in the group GK1 has good adhesion to the recording layer. From these _{facts, M2 Q3 Si R1 L2 T3 K1} J1 O 100-Q3-R1-T3-J1 ( atom%) system is an excellent oxide-based material layer. Incidentally, although the preferred atomic concentration above more than the element M 2 is 32 atomic%, or Si deteriorates the adhesion between the recording layer contains more than 35 atomic%, the element L2 is 40 atomic% If it is included, the rewrite performance is deteriorated repeatedly. Further, when the element K1 exceeds 40 atomic%, the transparency is lowered. Further, in this oxide-based material layer, transparency is lowered unless oxygen (O) is less than 20 atomic%. More preferable atomic concentrations are 0 <Q3 <25, 0 <R1 <25, 6 <T3 <37, 0 <J1 <35, 30 <Q3 + R1 + T3 + J1 <50.

As a component element in the case that contains the elements K 1 in the oxide-based material layer of the (III), for example, Zr-Si-La-Cr -O, Zr-Si-La-N-O, Zr- Si—La—C—O, Zr—Si—Ga—Cr—O, Zr—Si—La—N—O, Zr—Si—La—C—O, Zr—Si—Y—Cr—O, Zr— There are Si—Y—N—O, Zr—Si—Y—C—O, and the like, and it is considered that any two or more oxides are mixed in the layer. For example, in the case of Zr—Si—La—Cr—O, it is considered that ZrO ₂ —SiO ₂ —La ₂ O ₃ —Cr ₂ O ₃ is present. In particular, Zr—Si—Ga—Cr—O is an excellent material having high transparency, low thermal conductivity, high adhesion, high rewrite performance, and high film formation speed.

It is considered that other materials other than Zr—Si—La—Cr—O exist as mixed materials as follows. ZrO ₂ —SiO ₂ —La ₂ O ₃ —Si ₃ N ₄ , ZrO ₂ —SiO ₂ —La ₂ O ₃ —SiC, ZrO ₂ —SiO ₂ —Ga ₂ O ₃ —Si ₃ N ₄ , ZrO ₂ —SiO _{2 -Ga 2 O 3 -SiC, ZrO 2} -SiO 2 -Ga 2 O 3 -Cr 2 O 3, ZrO 2 -SiO 2 -In 2 O 3 -Si 3 N 4, ZrO 2 -SiO 2 -In 2 O 3 _{-SiC, ZrO 2 -SiO 2 -In 2} O 3 -Cr 2 O 3, _{also, HfO 2 -SiO 2 -La 2 O} 3 -Si 3 N 4, HfO 2 -SiO 2 -La 2 O 3 -SiC, HfO ₂ —SiO ₂ —La ₂ O ₃ —Cr ₂ O ₃ , HfO ₂ —SiO ₂ —Ga ₂ O ₃ —Si ₃ N ₄ , HfO ₂ —SiO ₂ —Ga ₂ O ₃ —SiC, HfO ₂ —SiO _{2 -Ga 2 O 3 -Cr 2 O 3} , HfO 2 -SiO 2 -In 2 O 3 -Si 3 N 4, HfO 2 -SiO 2 - n ₂ O ₃ -SiC, such as _{HfO 2 -SiO 2 -In 2 O 3} -Cr 2 O 3 and the like.

Moreover, Si may form only a carbide or nitride, and in that case, it is considered that the following mixed material exists. _{ZrO 2 -La 2 O 3 -Si 3} N 4, ZrO 2 -La 2 O 3 -SiC, ZrO 2 -Ga 2 O 3 -Si 3 N 4, ZrO 2 -Ga 2 O 3 -SiC, ZrO 2 -In ₂ O ₃ —Si ₃ N ₄ , ZrO ₂ —In ₂ O ₃ —SiC, ZrO ₂ —In ₂ O ₃ —Cr ₂ O ₃ , HfO ₂ —CeO ₂ —Si ₃ N ₄ , HfO ₂ —CeO _{2 -SiC, HfO 2 -Al 2 O 3} -Si 3 N 4, HfO 2 -Ga 2 O 3 -Si 3 N 4, HfO 2 -Ga 2 O 3 -SiC, HfO 2 -In 2 O 3 -Si 3 N ₄ , HfO ₂ —In ₂ O ₃ —SiC, and the like.

When using the oxide-based material layer of the (IV) as the dielectric layers 2 and 6, the oxide-based material layer is for example _{M2 Q4 Cr U L2 T4 O 100} -Q4-U-T4 ( atom%) (Formula M2 represents at least one element selected from the group GM2 consisting of Zr and Hf, L2 represents at least one element selected from the group GL2, and Q4, U and T4 are 0 <Q4 ≦ 32, 0 <U ≦ 25, 0 <T4 ≦ 40, 20 <Q4 + U + T4 <60 is satisfied.) When the element M4 is contained in an amount of more than 32 atomic%, the adhesion with the recording layer is deteriorated. When Cr is included, the adhesion to the recording layer is further improved. If the Cr content exceeds 25 atomic%, the transparency of the oxide-based material layer decreases. If the element L2 is contained in an amount of 40 atomic% or more, the repeated rewriting performance is deteriorated. Moreover, if oxygen (O) is less than 40 atomic%, the transparency is lowered. More preferably, 0 <Q4 <25, 0 <U <18, 6 <T4 <20, 30 <Q4 + U + T4 <50.

Examples of the component elements of the oxide-based material layer in this case include Zr—Cr—La—O, Zr—Cr—Hf—La—O, Hf—Cr—La—O, Zr—Cr—Ce—O, Zr—Cr—Hf—Ce—O, Hf—Cr—Ce—O, Zr—Cr—Al—O, Zr—Cr—Hf—Al—O, Hf—Cr—Al—O, Zr—Cr—Ga— O, Zr—Cr—Hf—Ga—O, Hf—Cr—Ga—O, Zr—Cr—In—O, Zr—Cr—Hf—In—O, Hf—Cr—In—O, Zr—Cr— Hf-Mg-O, Hf-Cr-Mg-O, Zr-Cr-Mg-O, Zr-Cr-YO, Zr-Hf-Cr-YO, Hf-Cr-YO, etc. In any case, it is considered that two or more oxides exist in the layer in a mixed form. For example, in the case of Zr—Cr—Ga—O, it is considered that ZrO ₂ —Cr ₂ O ₃ —Ga ₂ O ₃ is present. In particular, Zr—Cr—Ga—O is an excellent material having high transparency, low thermal conductivity, high adhesion, high rewrite performance, and high film formation rate.

It is considered that other materials other than Zr—Cr—Ga—O exist as mixed materials as follows. ZrO ₂ —Cr ₂ O ₃ —La ₂ O ₃ , ZrO ₂ —HfO ₂ —Cr ₂ O ₃ —La ₂ O ₃ , HfO ₂ —Cr ₂ O ₃ —La ₂ O ₃ , ZrO ₂ —Cr ₂ O ₃ — _{CeO 2, ZrO 2 -HfO 2 -Cr} 2 O 3 -CeO 2, HfO 2 -Cr 2 O 3 -CeO 2, ZrO 2 -Cr 2 O 3 -Al 2 O 3, ZrO 2 -HfO 2 -Cr 2 O _{3 -Al 2 O 3, HfO 2} -Cr 2 O 3 -Al 2 O 3, ZrO 2 -Cr 2 O 3 -Ga 2 O 3, ZrO 2 -HfO 2 -Cr 2 O 3 -Ga 2 O 3, HfO _{2 -Cr 2 O 3 -Ga 2 O} 3, ZrO 2 -Cr 2 O 3 -In 2 O 3, ZrO 2 -HfO 2 -Cr 2 O 3 -In 2 O 3, HfO 2 -Cr 2 O 3 -In _{2 O 3, ZrO 2 -Cr 2} O 3 -MgO, ZrO 2 -HfO 2 -Cr 2 O 3 -MgO, HfO 2 -Cr 2 O 3 -MgO, ZrO 2 -C _{2 O 3 -Y 2 O 3,} ZrO 2 -HfO 2 -Cr 2 O 3 -Y 2 O 3, HfO 2 -Cr 2 O 3 -Y 2 O 3, ZrO 2 -Cr 2 O 3 -Ga 2 O 3 such -Y ₂ O ₃ and the like.

  In FIG. 7, the composition range of the material represented by Formula (1) or (3) is shown. In FIG. 7, the coordinates are (M, L, O), and the unit is atomic%. The coordinate M indicates Zr or the element M1, and the coordinate L indicates the element L1 or L2. In this figure, the material represented by the formula (1) or (3) is a (34, 26, 40), b (10, 50, 40), c (0, 50, 50), d (0, 20, 80), e (20, 0, 80), and f (34, 0, 66).

  The oxide-based material layer (I) preferably contains 90 mol% or more of a Zr oxide and an oxide of an element selected from the group GL1. The oxide-based material layer (II) preferably contains 90 mol% or more of the oxide of M1 and the oxide of an element selected from the group GL2. The oxide-based material layer of (III) above contains a total of 90 mol% or more of an oxide of an element selected from the group GM2, an oxide of an element selected from the group GL2, and an oxide of Si. Is preferred. The oxide-based material layer (IV) includes 90 mol% or more of the oxide of the element selected from the group GM2, the oxide of the element selected from the group GL2, and the oxide of Cr. Is preferred. The layer containing 90 mol% or more of these compounds in total does not change its thermal stability and moisture resistance even if it contains a third component other than that, and the first dielectric layer 2 and the second dielectric layer. 6 is preferably used. The third component is inevitably included in forming the oxide-based material layer, may be added, or inevitably formed. As the third component, for example, a dielectric, metal, metalloid, semiconductor, and / or nonmetal is included in the oxide-based material layer. The dielectric may be contained in an amount of about 10 mol%, and the metal content is preferably 2 mol% or less. Further, the content of metalloid, semiconductor, and nonmetal is preferably 5 mol% or less.

More specifically, the dielectric contained as the third component is Bi ₂ O ₃ , Cr ₂ O ₃ , CuO, Cu ₂ O, Er ₂ O ₃ , FeO, Fe ₂ O ₃ , Fe ₃ O ₄ , Ho. ₂ O ₃ , GeO, GeO ₂ , a mixture of In ₂ O ₃ and SnO ₂ , Mn ₃ O ₄ , Nb ₂ O ₅ , Nd ₂ O ₃ , NiO, Sb ₂ O ₃ , Sb ₂ O ₄ , Sc ₂ O ₃ , SiO ₂ , Sm ₂ O ₃ , SnO, SnO ₂ , Ta ₂ O ₅ , Tb ₄ O ₇ , TeO ₂ , TiO ₂ , WO ₃ , Yb ₂ O ₃ , ZnO, 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 ZrC It is.

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

  More specifically, the semimetal and semiconductor contained as the third component are B, Al, C, Si, Ge, and Sn. More specifically, the nonmetal contained as the third component is Sb, Bi, Te, and Se.

  The first dielectric layer 2 and the second dielectric layer 6 are formed by changing the optical path length (that is, the product nd of the refractive index n of the dielectric layer and the film thickness d of the dielectric layer). Phase recording layer 4 light absorption rate Ac (%), amorphous phase recording layer light absorption rate Aa (%), and information recording medium 25 light reflectance Rc when recording layer 4 is in a crystalline phase (%) And 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 portion where the recording layer 4 is in the crystalline phase and the portion in which the recording layer 4 is in the amorphous phase It has the function of adjusting the phase difference Δφ of 25 lights. In order to increase the signal quality by increasing the reproduction signal amplitude of the recording mark, it is desirable that the reflectance difference (| Rc−Ra |) or the reflectance ratio (Rc / Ra) is large. Also, it is 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 (for example, see “Wave Optics” by Hiroshi Kubota, Iwanami Shinsho, 1971, Chapter 3).

The oxide-based material layer described above has a different refractive index depending on its composition. 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 expressed by nd = aλ. Here, a is a positive number. In order to increase the reproduction signal amplitude of the recording mark of the information recording medium 25 and improve the signal quality, for example, it is preferable that 15% ≦ Rc and Ra ≦ 2%. In order to eliminate or reduce the 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 determined by calculation based on the matrix method so that these preferable conditions were satisfied simultaneously. From the obtained optical path length (aλ) and λ and n, the thickness d of the dielectric layer was determined. As a result, for _{example, Zr Q3 Si R1 Ga T3 O} 100-Q3-R1-T3 ( atom%) and _{((ZrO 2) X3 (SiO} 2) Z1 (Ga 2 O 3) 100-X3-Z1 (mol%) When the first dielectric layer 2 is formed of a material having a refractive index n of 1.7 to 2.3, the thickness is preferably 100 nm to 200 nm. I found out. Moreover, when forming the 2nd dielectric material layer 6 with this material, it turned out that the thickness becomes like this. Preferably it is 20-80 nm.

The information recording medium in Embodiment 1 uses, as an example, the oxide-based material layer of the present invention for both the first dielectric layer 2 and the second dielectric layer 6. It is also possible to use the same material or materials having the same constituent elements but different composition ratios or materials having different constituent elements for the dielectric layer. For example, Zr ₆ Si ₆ Ga ₂₅ O ₆₃ (atomic%) may be used for the first dielectric layers 2 and 6, and Zr ₁₆ Si ₄ Ga ₁₇ O ₆₃ (atomic%) may be used for the first dielectric layer 2. Zr ₃ Si ₁₃ Ga ₂₁ O ₆₃ (atomic%) may be used for the second dielectric layer 6, and Zr ₁₃ Ga ₁₃ Y ₁₂ O ₆₂ (atomic%) may be used for the first dielectric layer 2. Alternatively, Hf ₃ Zr ₅ Si ₈ La ₁₂ Mg ₁₀ O ₆₂ (atomic%) may be used for the second dielectric layer 6.

  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 and the recording layer are formed. When the guide groove is formed on the substrate, the groove portion and the land portion are formed when the cross section of the substrate is viewed. In this specification, the surface on the side closer to the laser beam 12 is referred to as a “groove surface” for the sake of convenience, and the surface on the side farther from the laser beam is referred to as a “land surface” for the sake of convenience. 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 4 described later.

  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 shown in FIGS. 2, 3 and 4 to be described later, the step between the groove surface 23 and the land surface 24 is preferably within this range. The distance between the groove and the land (from the center of the groove surface 23 to the center of the land surface 24) is, for example, about 0.615 μm in the case of 4.7 GB / DVD-RAM. Moreover, it is desirable that the surface on the side where the layer is not formed is smooth.

  Examples of the material of the substrate 1 include resins such as polycarbonate, amorphous polyolefin or polymethyl methacrylate (PMMA), and glass. In view of moldability, price, and mechanical strength, polycarbonate is preferably used. In the illustrated form, 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 irradiation of light or application of electrical energy. If the phase transformation is reversible, it can be erased or rewritten.

As the reversible phase transformation material, it is preferable to use Ge—Sb—Te or Ge—Sn—Sb—Te, which is a high-speed crystallization material. Specifically, in the case of Ge-Sb-Te, preferably a GeTe-Sb ₂ Te ₃ pseudo-binary system composition, it is preferred that the case is a _{Sb 2 Te 3 ≦ GeTe ≦ 50Sb} 2 Te 3. In the case of GeTe <Sb ₂ Te ₃ , the change in the amount of reflected light before and after recording is small, and the quality of the read signal is lowered. In the case of 50Sb ₂ Te ₃ <GeTe, the volume change between the crystalline phase and the amorphous phase is large, and the repeated rewriting performance is lowered.

Ge—Sn—Sb—Te has a higher crystallization rate than Ge—Sb—Te. For example, Ge—Sn—Sb—Te is obtained by replacing a part of Ge having a GeTe—Sb ₂ Te ₃ pseudo binary system composition with Sn. In the recording layer 4, the Sn content is preferably 20 atomic% or less. If it exceeds 20 atomic%, the crystallization speed is too high, the stability of the amorphous phase is impaired, and the reliability of the recording mark is lowered. The Sn content can be adjusted according to the recording conditions.

  The recording layer 4 is formed of a material containing Bi 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 also 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 4Bi ₂ Te ₃ ≦ GeTe ≦ 50 Bi ₂ Te ₃ . In the case of GeTe <4Bi ₂ Te ₃ , the crystallization temperature is lowered and the recording storability tends to deteriorate. In the case of 50 Bi ₂ Te ₃ <GeTe, the volume change between the crystalline phase and the amorphous phase is large, and the repeated rewriting performance is lowered.

  Ge-Sn-Bi-Te corresponds to a Ge-Bi-Te in which part of Ge is replaced with Sn. It is possible to control the crystallization speed in accordance with the recording conditions by adjusting the substitution concentration of Sn. The Sn substitution is more suitable for fine adjustment of the crystallization speed of the recording layer than the Bi substitution. In the recording layer, the Sn content is preferably 10 atomic% or less. If it exceeds 10 atomic%, the crystallization speed becomes too fast, so that the stability of the amorphous phase is impaired and the storage stability of the recording mark is lowered.

Ge-Sn-Sb-Bi-Te corresponds to a Ge-Sb-Te in which a part of Ge is replaced with Sn and a part of Sb is replaced with Bi. This corresponds to a mixture of GeTe, SnTe, Sb ₂ Te ₃ and Bi ₂ Te ₃ . In this mixture, it is possible to adjust the Sn substitution concentration and the Bi substitution concentration to control the crystallization speed in accordance with the recording conditions. In Ge-Sn-Sb-Bi- Te, 2 (Sb-Bi) is preferably _{2 Te 3 ≦ (Ge-Sn} ) Te ≦ 50 (Sb-Bi) 2 Te 3. (Ge-Sn) Te <For _{2 (Sb-Bi) 2 Te} 3, the variation in the amount of reflected light before and after recording is small, the read signal quality is degraded. In the case of 50 (Sb—Bi) ₂ Te ₃ <(Ge—Sn) Te, the volume change between the crystalline phase and the amorphous phase is large, and the repeated rewriting performance is lowered. In the recording layer, the Bi content is preferably 10 atomic% or less, and the Sn content is preferably 20 atomic% or less. If the contents of Bi and Sn are within this range, good recording mark storability can be obtained.

  In addition, examples of materials that reversibly undergo phase transformation include Ag-In-Sb-Te, Ag-In-Sb-Te-Ge, and materials containing 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, etc.) as disclosed in, for example, Japanese Patent Publication No. 7-25209 (Japanese Patent No. 2006849). The information recording medium in which the recording layer is an irreversible phase change material is of a so-called write-once type in which recording is possible only once. Even in such an information recording medium, there is a problem in that the atoms in the dielectric layer diffuse into the recording layer due to heat during recording, and the signal quality is lowered. Therefore, the present invention is preferably applied not only to a rewritable information recording medium but also to a write-once information recording medium.

  When the recording layer 4 is made of a material that reversibly undergoes phase transformation (that is, when the information recording medium is a rewritable information recording medium), the thickness of the recording layer 4 is 20 nm or less as described above. It is preferably 15 nm or less.

  The recording layer may be made of a magneto-optical material that performs recording / erasing / reproduction by applying a magnetic field and irradiating light. The material includes at least one element of a rare earth metal group consisting of Tb, Gd, Dy, Nd, and Sm, and at least one element of a transition metal group consisting of Sc, Cr, Fe, Co, and Ni. A material containing can be used. Specifically, Tb-Fe, Tb-Fe-Co, Gd-Fe, Gd-Fe-Co, Dy-Fe-Co, Nd-Fe-Co, Sm-Co, Tb-Fe-Ni, Gd-Tb -Fe-Co, Dy-Sc-Fe-Co, etc. are mentioned. When the material of the recording layer is a magneto-optical material, the configuration of the information recording medium does not necessarily match that shown in FIGS. 1 to 6, but the oxide-based material layer of the present invention is a dielectric layer regardless of the recording material or the layer configuration. Can be used as

  As described above, the light absorption correction layer 7 adjusts the ratio Ac / Aa between the light absorption rate Ac when the recording layer 4 is in the crystalline state and the light absorption rate Aa when the recording layer 4 is in the amorphous state. It works to prevent 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 to 6 and an extinction coefficient k of 1 to 4. Specifically, amorphous Ge alloys such as Ge—Cr, Ge—Mo, and Ge—W, amorphous Si alloys such as Si—Cr, Si—Mo, and Si—W, Te compounds, It is also preferable to use a material selected from crystalline metals, semi-metals and semiconductor materials such as Ti, Zr, Nb, Ta, Cr, Mo, W, SnTe, and PbTe. The film thickness of the light absorption correction layer 7 is preferably 20 nm to 60 nm.

  The reflective layer 8 optically increases 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, making it easily amorphous. It has the function to do. Further, the reflective layer 8 protects the multilayer film including the light absorption correction layer 7, the recording layer 4, and the dielectric layers 2 and 6 from the use environment. Examples of the material of the reflective layer 8 include single metal materials having high thermal conductivity such as Al, Au, Ag, and Cu. The reflective layer 8 is selected from the above metal materials for the purpose of improving its moisture resistance and / or for adjusting the thermal conductivity or optical properties (eg, light reflectance, light absorption or light transmittance). It may be formed by using a material obtained by adding one or more elements to one or more other elements. Specifically, an alloy material such as Al—Cr, Al—Ti, Ag—Pd, Ag—Pd—Cu, Ag—Pd—Ti, or Au—Cr can be used. These materials are excellent materials having excellent corrosion resistance and a rapid cooling function. The same object can be achieved by forming the reflective layer 8 with two or more layers. The thickness of the reflective layer 8 is preferably 50 to 180 nm, and more preferably 60 to 120 nm.

  In the illustrated information recording medium 25, the adhesive layer 9 is provided to adhere the dummy substrate 10 to the reflective layer 8. The adhesive layer 9 may be formed using a material having high heat resistance and high adhesiveness, for example, an adhesive resin such as an ultraviolet curable resin. Specifically, the adhesive layer 9 may be formed of a material mainly composed of an acrylic resin or a material mainly composed of an epoxy resin. Further, if necessary, a protective layer made of an ultraviolet curable resin and having a thickness of 2 to 20 μm may be provided on the surface of the reflective layer 8 before the adhesive layer 9 is formed. The thickness of the adhesive layer 9 is preferably 15 to 40 μm, more preferably 20 to 35 μm.

  The dummy substrate 10 increases the mechanical strength of the information recording medium 25 and protects the stacked body from the first dielectric layer 102 to the reflective layer 8. The preferred material for the dummy substrate 10 is the same as the preferred material for the substrate 1. In the information recording medium 25 to which the dummy substrate 10 is bonded, the dummy substrate 10 and the substrate 1 are formed of substantially the same material and have the same thickness so that no mechanical warpage, distortion, or the like occurs. Is preferred.

  The information recording medium of Embodiment 1 is a single-sided structure disc 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 laminated up to the reflective layer 8 in Embodiment 1 with the reflective layers 8 facing each other and an adhesive layer. In this case, the two laminates are bonded together by forming an adhesive layer with a slow-acting resin and utilizing the action of pressure and heat. In the case where a protective layer is provided on the reflective layer 8, a laminated body formed up to the protective layer is bonded with the protective layers facing each other to obtain a double-sided information recording medium.

  Next, a method for manufacturing the information recording medium 25 of Embodiment 1 will be described. The information recording medium 25 has a substrate 1 (for example, a thickness of 0.6 mm) on which a guide groove (groove surface 23 and land surface 24) is formed disposed in a film forming apparatus, and the surface of the substrate 1 on which the guide groove is formed. The step of forming the first dielectric layer 2 (step a), the step of forming the recording layer 4 (step b), the step of forming the second dielectric layer 6 (step c), and light absorption A step of forming the correction layer 7 (step d) and a step of forming the reflective layer 8 (step e) are sequentially performed, a step of forming the adhesive layer 9 on the surface of the reflective layer 8, and a dummy substrate 10. It is manufactured by carrying out the step of laminating. In this specification including the following description, regarding each layer, “surface” refers to the surface exposed when each layer is formed (a surface perpendicular to the thickness direction) unless otherwise specified. And

First, the step a of forming the first dielectric layer 2 on the surface of the substrate 1 where the guide groove is formed is performed. Step a is performed by sputtering. Here, first, an example of a sputtering apparatus used in this embodiment will be described. FIG. 11 shows a state where a film is formed using a sputtering apparatus. As shown in FIG. 11, in this sputtering apparatus, a vacuum pump (not shown) is connected to the vacuum vessel 39 through the exhaust port 32 so that the inside of the vacuum vessel 39 can be kept at a high vacuum. A gas with a constant flow rate can be supplied from the gas supply port 33. A substrate 35 (here, the substrate is a base material on which a film is deposited ) is placed on the anode 34. By grounding the vacuum vessel 39, the vacuum vessel 39 and the substrate 35 are kept at the anode. The sputtering target 36 is connected to a cathode 37 and is connected to a power source via a switch (not shown). By applying a predetermined voltage between the anode 34 and the cathode 37, a thin film can be formed on the substrate 35 by the particles emitted from the sputtering target 36. Note that the same apparatus can be used for sputtering in the following steps.

  Sputtering in step a is performed in an Ar gas atmosphere using a high frequency power source. Sputtering may be performed in a mixed gas atmosphere in which Ar gas is mixed with at least one of oxygen gas and nitrogen gas of 5% or less. Since the sputtering target is a mixture of oxides, reactive sputtering is unnecessary, and an oxide-based material layer can be formed even in an atmosphere containing only Ar gas. As sputtering conditions, since there are few elements, conditions are easy to determine and suitable for mass production. When oxygen gas and / or nitrogen gas exceeding 5% is mixed with Ar gas, an oxide having a form different from a desired valence may be formed depending on the element, and an oxide-based material layer having desired characteristics may not be formed. is there. A pulse generating DC power source may be used as long as sputtering can be stably maintained.

  As the sputtering target used in step a, any one of the following four can be used.

(I) a sputtering target (for example, at least one element selected from an oxide of Zr and a group GL1) containing Zr, at least one element selected from the group GL1 consisting of La, Ga, and In and oxygen (O) Sputtering target containing an oxide of
(Ii) M1 (where M1 is a mixture of Zr and Hf or Hf), at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y, and oxygen A sputtering target containing (O) (for example, a sputtering target containing an oxide of M1 and an oxide of at least one element selected from the group GL2)
(Iii) at least one element selected from the group GM2 consisting of Zr and Hf, at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg, and Y, Si, oxygen ( (For example, a sputtering target including an oxide of at least one element selected from group GM2, an oxide of at least one element selected from group GL2, and an oxide of Si).
(Iv) at least one element selected from the group GM2 consisting of Zr and Hf, at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg, and Y, Cr, and oxygen ( (For example, a sputtering target including an oxide of at least one element selected from group GM2, an oxide of at least one element selected from group GL2, and an oxide of Cr).

  For the sputtering targets (i) to (iv), the oxides of essential elements (for example, in the case of (i), an oxide of Zr and an oxide of at least one element selected from the group GL1) are combined to 98 mol. % Or more is preferable. In this case, the remaining third component may contain the third component that may be included in the oxide-based material layer.

Specifically, for example, (D1) _x1 (E1) _100-x1 (mol%) (wherein D1 represents an oxide of Zr, E1 represents an oxide of at least one element selected from the group GL1, x1 is a sputtering target including a material that can be represented by 0 <x1 <100.) (D2) _x2 (E2) _100-x2 (mol%) (wherein D2 represents the oxide of M1) , E2 represents an oxide of at least one element selected from the group GL2, and x2 satisfies the following condition: 0 <x2 <100) (D3) _x3 (SiO ₂ ) _z1 (E2 ) _100-x3-z1 (mol%) (wherein D3 represents an oxide of at least one element selected from the group GM2, E2 represents an oxide of at least one element selected from the group GL2, x3 and z 1 may satisfy the following conditions: 10 ≦ x3 <90, 0 <z1 ≦ 50, 10 <x3 + z1 ≦ 90). When these sputtering targets are used, Zr _Q1 L1 _T1 O _100-Q1-T1 (atomic%) (wherein L1 represents at least one element selected from the group GL1, and Q1 and T1 are 0 < M1 _Q2 L2 _T2 O _100-Q2-T2 (atomic%) (in the formula, including the material represented by Q1 <34, 0 <T1 <50, 20 <Q1 + T1 <60) M1 represents a mixture of Zr and Hf or Hf, L2 represents at least one element selected from the group GL2, and Q2 and T2 are 0 <Q2 <34, 0 <T2 <50, 20 <Q2 + T2 < 60). M2 _Q3 Si _R1 L2 _T3 O _100-Q3-R1-T3 (atomic%) (wherein M2 is at least one selected from the group GM2) L2 is a small amount selected from the group GL2 It represents at least one element, and Q3, R1 and T3 satisfy the following conditions: 0 <Q3 ≦ 32, 0 <R1 ≦ 32, 3 <T3 <43, 20 <Q3 + R1 + T3 <60. A material layer or the like can be formed. In particular, when a ZrO ₂ —SiO ₂ —Ga ₂ O ₃ sputtering target is used, an excellent Zr—Ga—O oxide-based material layer is formed. When ZrO ₂ and SiO ₂ have the same molar concentration, a composite oxide ZrSiO ₄ of ZrO ₂ and SiO ₂ can be formed. In that case, for example, a sputtering target including a material that can be represented by (ZrSiO ₄ ) _a (E2) _100-a (mol%) (where a satisfies 11 ≦ a ≦ 82) is used. Can do. With this sputtering target, the oxide-based material layer containing the material expressed by _{Zr Q3 Si R1 L2 T3 O 100} -Q3-R1-T3 ( atom%) is formed. For example, a sputtering target that can be represented by (ZrO ₂ ) _{x 3} (SiO ₂ ) _{z 1} (Ga ₂ O ₃ ) _{100-x 3 -z 1} (mol%) is a mixture of Zr, Si, Ga and O powders. (Ga and O have low melting points, making it difficult to handle powder at room temperature). Generally, ZrO ₂ , SiO ₂ and Ga ₂ O ₃ powders are mixed and hardened under optimum temperature and pressure conditions. Built. In addition, some oxides of the same element include a plurality of oxides having different valences. Therefore, in order to form a desired oxide-based material layer, the oxide ratio is represented by (D1) _x1 (E1) _100-x1 (mol%), it is important notation _{(D2) x2 (E2) 100} -x2 (mol%), (D3) x3 (SiO 2) z1 (E2) 100-x3-z1 (mol%) . If necessary, like the oxide-based material layer, the powder of the sputtering target of these notations can be analyzed with an X-ray microanalyzer or the like, and the composition ratio of each element is Zr _q1 L1 _t1 O _{100-q1-t1 (atomic%), M1 q2 L2 t2 O} 100-q2-t2 ( atom%), obtained in _{M2 q3 Si r1 L2 t3 O 100} -q3-r1-t3 ( atom%).

FIG. 8 shows a composition range when SiO ₂ is used as g in the material represented by the formula (19). In FIG. 8, the coordinates are (D3, SiO ₂ , E2), and the unit is mol%. In this figure, the material represented by the formula (20) is g (90, 0, 10), h (40, 50, 10), i (10, 50, 40), j (10, 0, 90). The material is within the range surrounded by (including on the ghij line but not on the gy line).

Next, step b is performed to form the recording layer 4 on the surface of the first dielectric layer 2. Step b is also performed by sputtering. Sputtering is performed using a DC power source in an Ar gas atmosphere or in a mixed gas atmosphere of Ar gas and N ₂ gas. Sputtering targets are 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, step c is performed to form a 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 is selected from a sputtering target containing the same oxide in the same mixing ratio as the first dielectric layer 2, a sputtering target containing the same oxide but different in mixing ratio, or each group. A sputtering target containing different oxides can be used.

For example, a sputtering target containing (ZrO ₂ ) ₃₀ (SiO ₂ ) ₂₀ (Ga ₂ O ₃ ) ₅₀ (mol%) in steps a and c may be used, and (ZrO ₂ ) ₃₀ (SiO _{2 in} step a. ₂ ) Sputtering target containing (ZrO ₂ ) ₄₀ (SiO ₂ ) ₃₀ (Ga ₂ O ₃ ) ₃₀ (mol%) in step c using a sputtering target containing ₂₀ (Ga ₂ O ₃ ) ₅₀ (mol%) May be used. Alternatively, a sputtering target containing a HfO ₂ —Ga ₂ O ₃ mixed material may be used in step a, and a sputtering target containing a ZrO ₂ —SiO ₂ —Y ₂ O ₃ mixed material may be used in step c.

  Next, step d is performed to form a light absorption correction layer 7 on the surface of the second dielectric layer 6. In step d, sputtering is performed using a direct current power source or a high frequency power source. Sputtering targets include amorphous Ge alloys such as Ge—Cr, Ge—Mo, and Ge—W, amorphous Si alloys such as Si—Cr, Si—Mo, and Si—W, Te compounds, and Ti, Zr. , Nb, Ta, Cr, Mo, W, SnTe, and PbTe are used, which are made of a material selected from crystalline metals, metalloids, and semiconductor materials. Sputtering is performed in an Ar gas atmosphere.

  Next, step e is performed to form a reflective layer 8 on the surface of the light absorption correction layer 7. Step e is performed by sputtering. Sputtering is performed in an Ar gas atmosphere using a direct current power source or a high frequency power source. As a sputtering target, a single sputtering target made of a high thermal conductive material such as Au, Al, Ag, or Cu, or Al—Cr, Al—Ti, Ag—Pd, Ag—Pd—Cu, Ag—Pd—Ti, or Au—Cr. An alloy sputtering target such as can be used.

  As described above, steps a to e are all sputtering steps. Therefore, steps a to e may be performed continuously by sequentially changing the sputtering target in one vacuum chamber of the sputtering apparatus as shown in FIG. Moreover, you may implement process ae by arrange | positioning a sputtering target in the independent vacuum chamber of a sputtering device.

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

  After the bonding process is completed, an initialization process is performed as necessary. The initialization process is a process in which the recording layer 4 in an amorphous state is crystallized by, for example, irradiating a semiconductor laser and raising the temperature above the crystallization temperature. The initialization process may be performed before the bonding process. As described above, the information recording medium 25 of Embodiment 1 can be manufactured by sequentially performing the steps a to e, the adhesive layer forming step, and the dummy substrate bonding step.

(Embodiment 2)
As a second embodiment of the present invention, another example of an optical information recording medium that records and reproduces information using laser light will be described. FIG. 2 shows a partial cross section of the optical information recording medium. An information recording medium 26 shown in FIG. 2 has a first dielectric layer 2, a recording layer 4, a second interface layer 5, a second dielectric layer 106, and a light absorption correction layer 7 on one surface of the substrate 1. , And the reflective layer 8 are formed in this order, and the dummy substrate 10 is bonded to the reflective layer 8 with the adhesive layer 9. The information recording medium 26 shown in FIG. 2 is different from the conventional information recording medium 31 shown in FIG. 12 in that it does not have the first interface layer 103. Further, the information recording medium 26 is the information recording medium of Embodiment 1 shown in FIG. 1 in that the second dielectric layer 106 is laminated on the recording layer 4 via the second interface layer 5. 25. In the information recording medium 26, the first dielectric layer 2 is an oxide-based material layer as in the first embodiment. 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. 1. Therefore, detailed description of the elements already described with reference to FIG. 1 is 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, this interface layer is provided for convenience. 2 interface layer 5.

The information recording medium 26 in this form corresponds to a configuration in which the second dielectric layer 106 is formed of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) used in a conventional information recording medium. Therefore, the second interface layer 5 is provided in order to prevent mass transfer that occurs between the second dielectric layer 106 and the recording layer 4 due to repeated recording.

  As the second interface layer 5, the oxide-based material layer of the present invention can be used. Similar to the first dielectric layer 2 and the second dielectric layer 6 of the first embodiment, at least one element selected from the group GM consisting of Zr and Hf, and La, Ce, Al, Ga, In, It is a layer containing at least one element selected from the group GL consisting of Mg and Y and oxygen (O). Moreover, Si may be included and the 3rd component less than 10 atomic% may be included.

The second interface layer 5 may be formed of a conventionally used material containing Ge—N, a material containing ZrO ₂ —SiO ₂ —Cr ₂ O ₃ , or HfO ₂ —SiO ₂ —. it may be formed of a material containing cr ₂ O _3. In addition, it may be formed of a nitride such as Si—N, Al—N, Zr—N, Ti—N, or Ta—N, a nitrided oxide containing them, a carbide such as SiC, or C (carbon). Good. The thickness of the interface layer is preferably 1 to 10 nm, and more preferably 2 to 7 nm. If the thickness of the interface layer is large, the light reflectivity and light absorptance of the laminate 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 for manufacturing the information recording medium 26 of Embodiment 2 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 5 (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 reflective layer 8 are formed. The film is manufactured by sequentially performing the film forming process (process e), and further performing the process of forming the adhesive layer 9 on the surface of the reflective layer 8 and the process of bonding the dummy substrate 10 together. Since steps a, b, d, and e are as described in connection with the first embodiment, description thereof is omitted here. Hereinafter, only the steps that are not performed in the manufacture of the information recording medium of Embodiment 1 will be described.

  Step f is performed after the recording layer 4 is formed, and the second interface layer 5 is formed on the surface of the recording layer 4. In step f, sputtering is performed using a high frequency power source. As the sputtering target used in step f, the sputtering targets (i) to (iv) described in the first embodiment can be used. In this case, a sputtering target containing 90 mol% or more of oxides of essential elements (for example, in the case of (i), an oxide of Zr and an oxide of at least one element selected from the group GL1) may be used. it can. In the remaining less than 10 mol%, the third component that may be included in the oxide-based material layer may be included. The sputtering in step f is performed in an Ar gas atmosphere using a high-frequency power source, or in a mixed gas atmosphere in which at least one of oxygen gas and nitrogen gas of 5% or less is mixed with Ar gas. May be implemented. Since the sputtering target is a mixture of oxides, reactive sputtering is unnecessary, and an oxide-based material layer can be formed even in an atmosphere containing only Ar gas.

As the sputtering target used in the step f, may be used conventional sputtering target containing _{ZrO 2 -SiO 2 -Cr 2 O 3} , or a sputtering target containing HfO ₂ -SiO ₂ -Cr ₂ O ₃ Also in that case, using a high frequency power source, it is carried out in an Ar gas atmosphere, or in a mixed gas atmosphere in which at least one of oxygen gas and nitrogen gas of 5% or less is mixed with Ar gas. May be implemented. Alternatively, reactive sputtering may be performed in a mixed gas atmosphere of Ar gas and N ₂ gas using a sputtering target containing Ge—Cr, Ge, Si, Al, Zr, Ti, or Ta. According to this reactive sputtering, the second interface layer 5 containing Ge—Cr—N, Ge—N, Si—N, Al—N, Zr—N, Ti—N, or Ta—N becomes the recording layer 4. Formed on the surface. In addition, using a sputtering target including carbide such as SiC or C (carbon), sputtering may be performed with Ar gas, and may be formed using carbide such as SiC or C (carbon).

Next, step g is performed to form a second dielectric layer 106 on the surface of the second interface layer 5. In step g, a high frequency power source is used, for example, using a sputtering target made of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%), in an Ar gas atmosphere or in a mixed gas atmosphere of Ar gas and O ₂ gas. Then, sputtering is performed. Thereby, a layer made of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) is formed. Thereafter, after the process of bonding the dummy substrate 10 is completed, as described in connection with the first embodiment, an initialization process is performed as necessary to obtain the information recording medium 26.

(Embodiment 3)
As a third embodiment of the present invention, another example of an optical information recording medium that records and reproduces information using laser light will be described. FIG. 3 shows a partial cross section of the optical information recording medium.

An information recording medium 27 shown in FIG. 3 has a first dielectric layer 102, a first interface layer 3 , a recording layer 4, a second dielectric layer 6, and a light absorption correction layer 7 on one surface of the substrate 1. And the reflective layer 8 are formed in this order, and the dummy substrate 10 is bonded to the reflective layer 8 with the adhesive layer 9. The information recording medium 27 shown in FIG. 3 is different from the conventional information recording medium 31 shown in FIG. 12 in that it does not have the second interface layer 105. The information recording medium 27 is the same as that of the first embodiment shown in FIG. 1 in that the first dielectric layer 102 and the first interface layer 3 are laminated in this order between the substrate 1 and the recording layer 4. It is different from the information recording medium 25. In the information recording medium 27, the second dielectric layer 6 is an oxide-based material layer as in the first embodiment. 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. 1. Therefore, detailed description of elements already described in FIG. 1 is omitted.

The information recording medium 27 in this form corresponds to a configuration in which the first dielectric layer 102 is formed of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) used in the conventional information recording medium. Therefore, the first interface layer 3 is provided in order to prevent mass transfer that occurs 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 3 are the same as those of the second interface layer 5 of the information recording medium 26 of Embodiment 2 described with reference to FIG. Therefore, detailed description thereof is omitted.

  Next, a method for manufacturing the information recording medium 27 of Embodiment 3 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 where the guide groove is formed (step h), a step of forming the first interface layer 3 (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 reflective layer 8 are formed. The film is manufactured by sequentially performing the film forming process (process e), and further performing the process of forming the adhesive layer 9 on the surface of the reflective layer 8 and the process of bonding the dummy substrate 10 together. Since steps b, c, d, and e are as described in connection with the first embodiment, the description thereof is omitted here. Hereinafter, only the steps that are not performed in the manufacture of the information recording medium of Embodiment 1 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 step g described in relation to the manufacturing method of the second embodiment. Step i is a step of forming the first interface layer 3 on the surface of the first dielectric layer 102. The specific method is the same as step f described in relation to the manufacturing method of the second embodiment. Thereafter, after the process of bonding the dummy substrate 10 is completed, as described in relation to the first embodiment, an initialization process is performed as necessary to obtain the information recording medium 27.

(Embodiment 4)
As a fourth embodiment of the present invention, another example of an optical information recording medium that records and reproduces information using laser light will be described. FIG. 4 shows a partial cross section of the optical information recording medium.

  An information recording medium 28 shown in FIG. 4 has 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, the light absorption correction layer 7, and the reflection layer 8 are formed in this order, and the dummy substrate 10 is bonded to the reflection layer 8 with the adhesive layer 9. In the information recording medium 28 shown in FIG. 4, the first and second interface layers 3 and 5 are oxide-based material layers. 4, the same reference numerals as those used in FIGS. 1 to 3 represent the same elements, and are formed by the materials and methods described with reference to FIGS. 1 to 3. Therefore, detailed description of elements already described with reference to FIGS. 1 to 3 is omitted.

In this type of information recording medium, the first and second dielectric layers 102 and 106 are made of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%), which has been used in conventional information recording media. This corresponds to a configuration in which the first and second interface layers 3 and 5 are formed of an oxide material layer. Preferred materials for the first and second interface layers 3 and 5 are the same as those for the first and second dielectric layers 2 and 6 of the first embodiment. Therefore, detailed description thereof will be omitted. The thickness of the first and second interface layers 3 and 5 is preferably 1 to 10 nm, and more preferably about 2 to 7 nm so as not to affect the recording / erasing performance. The interface layer, which is an oxide-based material layer, has a lower material cost, a lower extinction coefficient (higher transparency), and a higher melting point than a conventional interface layer made of a nitride containing Ge. It has the advantage of being thermally stable.

  Note that the first and second dielectric layers 102 and 106 may be made of the same material or different materials.

  Next, a method for manufacturing the information recording medium 28 of Embodiment 4 will be described. In the information recording medium 28, a step of forming the first dielectric layer 102 on the surface of the substrate 1 where the guide groove is formed (step h), a step of forming the first interface layer 3 (step i), A step of forming the recording layer 4 (step b), a step of forming the second interface layer 5 (step f), a step of forming the second dielectric layer 106 (step g), and a light absorption correction layer. 7 (step d) and the step of forming the reflective layer 8 (step e) are sequentially performed, and the step of forming the adhesive layer 9 on the surface of the reflective layer 8 and the dummy substrate 10 are bonded together. It is manufactured by carrying out the process. Step h is as described in connection with the third embodiment, steps b, d and e are as described in connection with the first embodiment, and step g is related to the second embodiment. Therefore, the description thereof is omitted here.

The second dielectric layer 106 may be formed using a sputtering target containing the same material as the first dielectric layer 102 or a different sputtering target. For example, a sputtering target containing (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) in both steps h and g may be used, and (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) is contained in step h. A sputtering target may be used, and a sputtering target containing (ZrO ₂ ) ₃₀ (SiO ₂ ) ₃₀ (Cr ₂ O ₃ ) ₂₀ (LaF ₃ ) ₂₀ (mol%) in step g may be used. Both sputterings can be performed using a high frequency power source in an Ar gas atmosphere or a mixed gas atmosphere in which at least one of oxygen gas or nitrogen gas and Ar gas are mixed.

  Step i is a step of forming the first interface layer 3 on the surface of the first dielectric layer 102. Step i is performed in the same manner as in the third embodiment. As the sputtering target used in step i, the sputtering targets (i) to (iv) described in Embodiment 1 can be used. In this case, a sputtering target containing 90 mol% or more of oxides of essential elements (for example, in the case of (i), an oxide of Zr and an oxide of at least one element selected from the group GL1) may be used. it can. In the remaining less than 10 mol%, the third component that may be included in the oxide-based material layer may be included. In this case, sputtering is performed in an Ar gas atmosphere using a high frequency power source, or in a mixed gas atmosphere in which at least one of oxygen gas and nitrogen gas of 5% or less is mixed with Ar gas. May be implemented. Since the sputtering target is a mixture of oxides, reactive sputtering is unnecessary, and an oxide-based material layer can be formed even in an atmosphere containing only Ar gas.

  Note that the information recording medium in Embodiment 4 uses the oxide-based material layer of the present invention for both the first interface layer 3 and the second interface layer 5 as an example. An information recording medium configured to use only the layer 3 and use another material for the second interface layer or use only another material for the second interface layer 5 and use another material for the first interface layer is implemented. It is also possible. When the oxide-based material layer of the present invention is used for both the first interface layer 3 and the second interface layer 5, it is possible to use different compositions within the range shown in FIG. 7 for each interface layer. is there.

  Step f is a step of forming the second interface layer 5 on the surface of the recording layer 4. Step f is performed in the same manner as in the second embodiment. The sputtering target used in the step f is the same as the sputtering target used in the step i.

  After the process of bonding the dummy substrate 10 is completed, as described in connection with the first embodiment, an initialization process is performed as necessary to obtain the information recording medium 28.

(Embodiment 5)
As a fifth embodiment of the present invention, another example of an optical information recording medium that records and reproduces information 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, the reflective layer 8, the second dielectric layer 6, the recording layer 4, and the first dielectric layer 2 are formed in this order on one surface of the substrate 101, and an adhesive layer is further formed. 9, the dummy substrate 110 is bonded to the first dielectric layer 2. This information recording medium 29 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 and uses the substrates 101 and 110. The information recording medium having this configuration is different from the information recording medium 25 having the configuration shown in FIG. 1 in that it does not have the light absorption correction layer 7.

  The laser beam 12 is incident on the information recording medium 29 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 down the laser beam to form a small recording mark in the recording layer. In order to narrow the beam, it is necessary to increase the numerical aperture NA of the objective lens. However, as the NA increases, the focal position becomes shallower. Therefore, it is necessary to thin the substrate on which the laser light is incident. In the information recording medium 29 shown in FIG. 5, the dummy substrate 110 on the side on which the laser light is incident does not need to function as a support when forming a recording layer or the like, and thus the thickness can be reduced. . Therefore, according to this configuration, it is possible to obtain the large-capacity information recording medium 29 capable of higher density recording. 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 oxide-based material layers as in the first embodiment. The oxide material layer is applied as a dielectric layer regardless of the order of formation of the reflective layer and the recording capacity. Since the materials included in the oxide-based material layer are as described in connection with Embodiment 1, detailed descriptions thereof are omitted.

  As described above, the information recording medium 29 is suitable for recording / reproducing with a laser beam having a short wavelength. Therefore, the thicknesses of the first and second dielectric layers 2 and 6 are obtained from a preferable optical path length when λ = 405 nm, for example. In order to improve the signal quality by increasing the reproduction signal amplitude of the recording mark of the information recording medium 29, for example, the first dielectric layer 2 and the second dielectric layer so as to satisfy 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, when the oxide-based material layer having a refractive index of 1.8 to 2.5 is used as the first and second dielectric layers 2 and 6, the thickness of the first dielectric layer 2 is preferably It was found that the thickness was 30 nm to 100 nm, and more preferably 50 nm to 80 nm. Moreover, it turned out that the thickness of the 2nd dielectric material layer 6 becomes like this. Preferably it is 3-50 nm, More preferably, it is 10-30 nm.

  The substrate 101 is a transparent disk-like 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 the side where the reflective layer or the like is to be formed. When the guide groove is formed, as described in connection with the first embodiment, the surface 23 on the side close to the laser beam 12 is called a groove surface 23 for convenience and the surface 24 on the side far from the laser beam 12 is used. Is called a land surface. In the substrate 101, the level difference 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. Moreover, it is desirable that the surface on the side where the layer is not formed is smooth. As the material of the substrate 101, the same material as the material of the substrate 1 of Embodiment 1 can be given. The thickness of the substrate 101 is preferably about 1.0 to 1.2 mm. A preferable thickness of the substrate 101 is larger than that of the substrate 1 of the first embodiment. This is because, as will be described later, since the dummy substrate 110 is thin, it is necessary to ensure the strength of the information recording medium with the substrate 101.

  Similar to the substrate 101, the dummy substrate 110 is a transparent disk-shaped plate. As described above, according to the configuration shown in FIG. 4, it is possible to perform recording with a laser beam having a short wavelength by reducing the thickness of the dummy substrate 110. Therefore, the thickness of the dummy substrate 110 is preferably 40 μm to 110 μm. The total thickness of the adhesive layer 9 and the dummy substrate 110 is more preferably 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. Further, since the dummy substrate 110 is located on the incident side of the laser beam 12, it is optically preferable that the birefringence in the short wavelength region is small and transparent.

  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.

  In addition, since the element which attached | subjected the code | symbol same as Embodiment 1 is as having already demonstrated in relation to Embodiment 1, the description is abbreviate | omitted.

In a modification of the information recording medium of this embodiment, for example, only the first dielectric layer is an oxide material layer, and the second dielectric layer is (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%). By forming, a second interface layer may be formed 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 an oxide-based material layer, and the first dielectric layer is (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%). ), A first interface layer may be formed between the first dielectric layer and the recording layer.

  Next, a method for manufacturing the information recording medium 29 of Embodiment 5 will be described. In the information recording medium 29, a substrate 101 (for example, a thickness of 1.1 mm) on which guide grooves (groove surface 23 and land surface 24) are formed is disposed in a film forming apparatus, and the surface of the substrate 101 on which the guide grooves are formed. The step of forming the reflective layer 8 (step e), the step of forming the second dielectric layer 6 (step c), the step of forming the recording layer 4 (step b), and the first dielectric By sequentially performing the step of forming the layer 2 (step a), and further, 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, Manufactured.

  First, step e is performed to form the reflective layer 8 on the surface of the substrate 101 where the guide groove is formed. The specific method for carrying out step e is as described in connection with the first embodiment. Next, step c, step b, and step a are performed in this order. The specific method for carrying out steps c, b and a is as described in connection with the first embodiment. Similar to the information recording medium of the first embodiment, in the manufacture of the information recording medium of this embodiment, the sputtering target used in the step c may be different from the sputtering target used in the step a. In the information recording medium manufacturing method of this embodiment, the execution order of each step is different from that in the information recording medium manufacturing method of the first embodiment.

  After the first dielectric layer 2 is formed, the substrate 101 sequentially laminated from the reflective layer 8 to the first dielectric layer 2 is taken out from 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, thereby completing the bonding step. By forming the adhesive layer 9 to a thickness of 50 μm to 120 μm and irradiating it with ultraviolet rays, the step of bonding the dummy substrate 110 can be omitted.

  After the bonding process is completed, an initialization process is performed as necessary. The method of the initialization process is as described in connection with the first embodiment.

(Embodiment 6)
As Embodiment 6 of the present invention, another example of an optical information recording medium in which recording and reproduction are performed using laser light will be described. FIG. 6 shows a partial cross section of the optical information recording medium.

  In the information recording medium 30 shown in FIG. 6, the second information layer 22, the intermediate layer 16, and the first information layer 21 are formed in this order on one surface of the substrate 101, and the dummy substrate 110 is further interposed via the adhesive layer 9. The first information layer 21 is stacked. More specifically, the second information layer 22 includes the second reflective layer 20, the fifth dielectric layer 19, the second recording layer 18, and the 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 is formed on the surface of the intermediate layer 16 on the third dielectric layer 15, the first reflective layer 14, the second dielectric layer 6, the first recording layer 13, and the first dielectric layer. The body layer 2 is formed in this order. Also in this embodiment, the laser beam 12 is incident from the dummy substrate 110 side. Moreover, in the information recording medium of this form, information can be recorded on each of the two recording layers. Therefore, according to this configuration, an information recording medium having a capacity about twice that of the fifth embodiment can be obtained. Specifically, according to this configuration, for example, it is possible to obtain an information recording medium with a capacity of 50 GB, which uses, for example, a laser beam in a blue-violet region near a wavelength of 405 nm for recording and reproduction.

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

  In the information recording medium 30 of the form shown in FIG. 6, the fifth dielectric layer 19, the fourth dielectric layer 17, the second dielectric layer 6, and the first dielectric layer 2 are provided with an oxide-based material. Layers can be used. If an oxide-based material layer is used, a second recording layer is formed between the first recording layer 13 and the first dielectric layer 2, between the first recording layer 13 and the second dielectric layer 6, and so on. The interface layer between the second recording layer 18 and the fifth dielectric layer 19 between the layer 18 and the fourth dielectric layer 17 becomes unnecessary. Since the specific material of the oxide-based material layer is as described in connection with Embodiment 1, detailed description thereof will be 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 formed by selecting materials so that the thermal conductivity of the layers is low and the effect of quenching the second and first recording layers 18 and 13 is high. It is preferable to do. Specifically, these layers are formed of, for example, Zr ₁₅ Si ₁₁ Ga ₁₁ O ₆₃ (atomic%) (oxide display (ZrO ₂ ) ₄₀ (SiO ₂ ) ₃₀ (Ga ₂ O ₃ ) ₃₀ (mol%)). It is preferable that it is a layer containing the material represented by these. The film thicknesses of the fifth and second dielectric layers 19 and 6 are preferably 3 nm to 50 nm, and more preferably 10 nm to 30 nm.

In the second information layer 22 and the first information layer 21, the laser light 12 reaches the second dielectric layer 17 and the first dielectric before reaching the second recording layer 18 and the first recording layer 13. It is incident on the layer 2. Therefore, it is desirable that the fourth and first dielectric layers 17 and 2 are made of a material that is transparent and has low thermal conductivity. Specifically, these layers are formed of, for example, Zr ₆ Si ₆ Ga ₂₅ O ₆₃ (atomic%) (oxide display (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₅₀ (mol%)). It is preferable that it is a layer containing the material represented by these. The film thickness of the fourth and first dielectric layers 17 and 2 is preferably 30 nm to 80 nm.

  As described above, also in the information recording medium having a single-sided two-layer structure as shown in FIG. 6, the dielectric layers located on both sides of the recording layer are made of the oxide material layers, so that the dielectric layers are interposed via the interface layer. And can be formed so as to be in direct contact with the recording layer. Therefore, according to the present invention, it is possible to reduce the number of layers constituting the entire information recording medium having a single-sided two-layer structure. In addition, by adjusting the refractive index and the recording sensitivity of the medium by selecting plural types of oxides included in the material constituting the dielectric layer and / or appropriately selecting the type of oxide, information can be obtained. It can be optimized according to the type of 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. A material that satisfies these conditions is TiO ₂ . When a TiO ₂ material containing 90 mol% or more of TiO ₂ is used, a layer having a large refractive index of about 2.7 is formed. The film thickness of the third dielectric layer 15 is preferably 10 nm to 30 nm.

  The substrate 101 is the same as the substrate 101 of the fifth embodiment. Therefore, detailed description of the substrate 101 is omitted here.

  The second reflective layer 20 is the same as the reflective layer 8 of the first embodiment. 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 light in the first information layer 21 and the focal position in the second information layer 22 are significantly different. In the intermediate layer 16, a guide groove is formed 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 preferably transparent to light having a wavelength λ to be recorded / reproduced 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 laser light wavelength λ. 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. Further, 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 a range where the objective lens can collect light. It is preferable that the thickness of the dummy substrate 110 is within the allowable substrate thickness tolerance for the objective lens to be used. Accordingly, the thickness of the intermediate layer is preferably 10 μm to 40 μm. The intermediate layer 16 may be configured by laminating a plurality of resin layers as necessary. Specifically, a two-layer structure of a layer that protects the fourth dielectric layer 17 and a layer having a guide groove may be used.

  The first reflective layer 14 has a function of quickly diffusing the heat of the first recording layer 13. Further, when recording / reproducing the second information layer 22, since the laser light 12 transmitted through the first information layer 21 is used, the first information layer 21 needs to have a high light transmittance as a whole. Has a light transmittance of 45% or more. Therefore, the material and thickness of the first reflective layer 14 are limited as compared to 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 to 15 nm.

The first recording layer 13 is also limited in material and film thickness as compared with the second recording layer 18 in order to ensure the high light transmittance of the first information layer 21. The first recording layer 13 is preferably formed so 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 7 nm or less. Even when the material constituting the first recording layer 13 is such a thin film thickness, a good recording mark can be formed by melting and quenching, and a high-quality signal can be reproduced. Is selected to ensure that it can be erased. Specifically, Ge—Sb—Te such as GeTe—Sb ₂ Te ₃ based material which is a reversible phase transformation material, or Ge— in which Ge of GeTe—Sb ₂ Te ₃ based material is replaced with Sn. It is preferable to form the first recording layer 13 with 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. Specifically, for example, Ge ₂₂ Sb ₂ Te ₂₅ or Ge ₁₉ Sn ₃ Sb ₂ Te _{25 in} which GeTe: Sb ₂ Te ₃ = 22: 1 is preferably used.

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

  The dummy substrate 110 is the same as the dummy substrate 110 of the fifth embodiment. Therefore, detailed description regarding the dummy substrate is omitted here. Also in this embodiment, 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.

  In the information recording medium of this embodiment, only one dielectric layer among 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 an oxide-based material layer. Alternatively, two or three dielectric layers may be oxide-based material layers. When one dielectric layer is an oxide-based material layer, at least one interface layer is unnecessary, and when two dielectric layers are oxide-based material layers, at least two interface layers are not required. It becomes. Therefore, in the information recording medium of this form, a maximum of four interface layers can be eliminated. If necessary, an interface layer for preventing mass transfer between the recording layer and the dielectric layer may be provided between the dielectric layer that is not an oxide-based material layer and the recording layer. In that case, the interface layer can be an oxide material layer in the form of a very thin film having a thickness of about 5 nm.

  In the foregoing, an information recording medium having two information layers having a 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. Further, in the modification of the illustrated embodiment, for example, one of two information layers is an information layer having a recording layer that generates a reversible phase transformation, and one is an information having a recording layer that generates 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 can also be used. As described above, there are various types of information recording media having two or more information layers. In any form, the necessity of providing an interface layer between the recording layer and the dielectric layer can be eliminated by making the dielectric layer an oxide-based material layer.

  In the information recording medium having two or more recording layers, the oxide-based material layer may exist as an interface layer located between the recording layer and the dielectric layer. Such an interface layer is formed into a very thin film having a thickness of about 5 nm.

  Next, a method for manufacturing the information recording medium 30 of Embodiment 6 will be described. The information recording medium 30 includes a step of forming the second reflective layer 20 on the substrate 101 (step j), a step of forming the fifth dielectric layer 19 (step k), and forming the second recording layer 18. The step of forming a film (step l) and the step of forming the fourth dielectric layer 17 (step m) are sequentially performed, and then the step of forming the intermediate layer 16 on the surface of the fourth dielectric layer 17 is performed. Then, the step of forming the third dielectric layer 15 on the surface of the intermediate layer 16 (step n), the step of forming the first reflective layer 14 (step o), and the second dielectric layer 6 are formed. A step of forming a film (step p), a step of forming the first recording layer 13 (step q), and a step of forming the first dielectric layer 2 (step r) are sequentially performed. The first dielectric layer 2 is manufactured by performing the step of forming the adhesive layer 9 on the surface of the dielectric layer 2 and the step of bonding the dummy substrate 110 together.

  Steps j to m correspond to steps for 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 where the guide groove is formed. Step j is performed in the same manner as step e of the first embodiment. Next, step 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 the second recording layer 18 on the surface of the fifth dielectric layer 19. Step l is performed in the same manner as step b of the first embodiment. Finally, step m is performed to form a fourth dielectric layer 17 on the surface of the second recording layer 18. Step m is performed in the same manner as step a in the first embodiment.

  The substrate 101 on which the second information layer 22 is formed in steps j to m is taken out from 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 concavo-convex forming surface of the polycarbonate substrate having the concavo-convex complementary to the guide groove to be formed in the intermediate layer is brought into close contact with the ultraviolet curable resin. In this state, the resin is cured by irradiating ultraviolet rays, and then the polycarbonate substrate having unevenness is peeled off. Thereby, a guide groove having a shape complementary to the unevenness is formed in the ultraviolet curable resin, and the intermediate layer 16 having the guide groove as shown is formed. Alternatively, the intermediate layer 16 may be formed by forming a layer that protects the fourth dielectric layer 17 with an ultraviolet curable resin and forming a layer having guide grooves thereon. In that case, the obtained intermediate layer has a two-layer structure. Alternatively, the intermediate layer may be formed by stacking three or more layers.

  The substrate 101 formed up to the intermediate layer 16 is again placed in the sputtering apparatus, 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 grooves. 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 source and a sputtering target containing a TiO ₂ material. Further, if the oxygen deficient TiO ₂ sputtering target is used, sputtering can be performed using a pulse generation type DC power source.

  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 using an alloy sputtering target containing Ag. Next, step p is performed to form the second dielectric layer 6 on the surface of the first reflective 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, using the DC power supply, for example, GeTe-Sb is ₂ Te ₃ based materials Ge-Sb-Te, for example, a part of Ge of GeTe-Sb ₂ Te ₃ based material with a material obtained by substituting Sn Any one material selected from Ge—Sn—Sb—Te, Ge—Bi—Te, Ge—Sn—Bi—Te, Ge—Sb—Bi—Te, and Ge—Sn—Sb—Bi—Te Sputtering is performed in an Ar gas atmosphere or a mixed gas atmosphere of Ar gas and N ₂ gas, using the sputtering target.

  Next, step 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 step m. In this way, the steps n to r are sequentially performed to form the first information layer 21.

  The substrate 101 formed up to the first information layer 21 is taken out from the sputtering apparatus. 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, thereby completing the bonding step. Also in the method for manufacturing the information recording medium of the sixth embodiment, the step of bonding the dummy substrate 110 can be omitted as in the method of manufacturing the information recording medium of the fifth embodiment.

  After the bonding process is completed, an initialization process of 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 for performing the initialization step is as described in connection with the first embodiment.

  The optical information recording medium that records and reproduces with laser light has been described as an embodiment of the information recording medium of the present invention with reference to FIGS. The optical information recording medium of the present invention is not limited to these forms. The optical information recording medium of the present invention can be provided with an oxide-based material layer as one of the constituent layers so as to be in contact with the recording layer, and can take any form. Further, even if it is not in contact with the recording layer, it can be arbitrarily used as a dielectric layer included in the information recording medium. That is, the present invention is applied regardless of the order in which layers are formed on the substrate, the number of recording layers, recording conditions, recording capacity, and the like. 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 that records and reproduces with a laser beam with a wavelength of 630 to 680 nm, or a large-capacity optical disk that records and reproduces with a laser beam with a wavelength of 400 to 450 nm. It's okay.

(Embodiment 7)
As an embodiment 7 of the present invention, an example of an information recording medium for recording and reproducing information by applying electrical energy will be described. FIG. 9 shows a partial cross section of the information recording medium.

  FIG. 9 shows a memory 207 in which a lower electrode 202, a recording unit 203, and an upper electrode 204 are formed in this order on the surface of a substrate 201. 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 laminated. There is no relationship. However, since both the recording layer 205 and the dielectric layer 206 constitute part of the stacked body including the substrate 201, the lower and upper electrodes 202 and 204 in the memory 207, they can be called “layers”, respectively. It is. Therefore, the information recording medium of the present invention includes those in which the recording layer and the dielectric layer are on the same plane.

Specifically, as the substrate 201, 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 sputtering a metal such as Au, Ag, Pt, Al, Ti, W, and Cr, and a mixture thereof.

The recording layer 205 constituting the recording unit 203 is made of a material that changes phase by applying electric energy, and can also be called a phase change unit. The recording layer 205 is formed of a material that changes in phase between a crystalline phase and an amorphous phase by Joule heat generated by applying electrical 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.

  The dielectric layer 206 constituting the recording unit 203 prevents a current flowing in the recording layer 205 from escaping to the peripheral portion by applying a voltage between the upper electrode 204 and the lower electrode 202, and the recording layer 205. Has a function of electrically and thermally isolating them. Therefore, the dielectric layer 206 can also be referred to as a heat insulating part. The dielectric layer 206 is an oxide material layer, specifically, the oxide material layers (I) to (IV) described above. The oxide-based material layer is preferably used because of its high melting point, difficulty in diffusing atoms in the material layer even when heated, and low thermal conductivity.

  This memory 207 will be further described together with its operation method in the embodiments described later.

  Next, the present invention will be described in detail using examples.

(Test 1)
The relationship between the nominal composition of the sputtering target made of an oxide-based material used in the production of the information recording medium of the present invention (in other words, the composition publicly displayed by the sputtering target manufacturer at the time of supply) and its analytical composition This was confirmed by testing.

In this test, the sputtering target, whose nominal composition was represented by (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₅₀ (mol%) corresponding to the above formula (19), was powdered, and X-ray Composition analysis was carried out by the microanalyzer method. As a result, the analytical composition of the sputtering target was obtained not as the formula (19) indicated by the ratio (mol%) of the compound but as the formula (17) indicated by the ratio (atomic%) of each element. The analysis results are shown in Table 1. Further, Table 1 shows a converted composition which is an elemental composition calculated from the nominal composition.

  As shown in Table 1, the analytical composition was almost equal to the converted composition. From this result, the actual composition (i.e., analytical composition) of the sputtering target represented by the equation (19) substantially matches the elemental composition (i.e., converted composition) obtained by calculation, and therefore the nominal composition is appropriate. It was confirmed.

(Test 2)
The relationship between the nominal composition of the sputtering target made of an oxide-based material used in the production of the information recording medium of the present invention and the analytical composition of the oxide-based material layer formed using this sputtering target was confirmed by a test. Specifically, a sputtering target (diameter 100 mm, thickness) in which the nominal composition is represented by (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₅₀ (mol%), which corresponds to the above formula (19). 6 mm) was attached to a film forming apparatus (that is, a sputtering apparatus), and sputtered at a power of 400 W using a high frequency power source in an Ar gas atmosphere under a pressure of 0.13 Pa. By this sputtering, an oxide-based material layer having a thickness of 500 nm was formed on the Si substrate. The composition analysis of this oxide-based material layer was also performed by the X-ray microanalyzer method. The analytical composition of the oxide-based material layer was also obtained as a formula (5) represented by a ratio (atomic%) of each element, not a formula (7) represented by a ratio (mol%) of a compound. The analysis results are shown in Table 2. Furthermore, the conversion composition calculated from the nominal composition of a sputtering target is shown in Table 2.

  As shown in Table 2, the analytical composition of the layer was approximately equal to the equivalent composition of the sputtering target. From this result, the actual composition of the oxide-based material layer formed by using the sputtering target represented by the equation (19) almost coincides with the converted composition calculated from the nominal composition of the sputtering target. It was confirmed that when the sputtering target represented by 19) was used, films having substantially the same composition were formed.

  The same results as in Tests 1 and 2 show that the mixing ratio of the oxide of at least one element selected from Zr and Hf and the oxidation of at least one element selected from La, Ce, Al, Ga, In, Mg, and Y It is thought that it can be obtained for other sputtering targets that are provided with the mixing ratio of the product. Therefore, in the following examples, the composition of the sputtering target is expressed by the nominal composition (mol%). Further, it was considered that the nominal composition of the sputtering target and the composition (mol%) of the oxide-based material layer formed by the sputtering method using the sputtering target can be regarded as the same. Accordingly, in the following examples, the composition of the dielectric layer is also displayed by displaying the composition of the sputtering target. Moreover, in the following examples, the composition of the sputtering target and the oxide-based material layer is expressed only by the ratio (mol%) of the compound. A person skilled in the art can easily calculate the elemental composition (atomic%) of the sputtering target and the oxide-based material layer based on the ratio (mol%) of each compound.

Example 1
In Example 1, in order to investigate the transparency of the oxide-based material layer, the complex refractive index (n-ki, n: refractive index, k: extinction coefficient) in the red region (wavelength 660 nm) and the blue-violet region (wavelength 405 nm). ) Was measured. As a procedure, a sample piece in which a thin film containing an oxide-based material was formed on a quartz glass substrate was prepared, and the complex refractive index of the thin film was measured by ellipsometry. The prepared oxide-based material includes a mixture of an oxide of at least one element selected from Zr and Hf and an oxide of at least one element selected from La, Ce, Al, Ga, In, Mg, and Y. And a mixture of Si oxides. (ZrO ₂ ) ₂₀ (La ₂ O ₃ ) ₈₀ , (ZrO ₂ ) ₂₀ (CeO ₂ ) ₈₀ , (ZrO ₂ ) ₂₀ (Al ₂ O ₃ ) ₈₀ , (ZrO ₂ ) ₂₀ ( _{Ga 2 O 3) 80, (} ZrO 2) 20 (In 2 O 3) 80, (ZrO 2) 20 (MgO) 80, (ZrO 2) 20 (Y 2 O 3) 80, and Comparative example (ZrO ₂ ) ₂₀ (Cr ₂ O ₃ ) ₈₀ and further mixed with SiO ₂ (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (La ₂ O ₃ ) ₅₀ , (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (CeO ₂ ) ₅₀ , (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Al ₂ O ₃ ) ₅₀ , (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₅₀ , (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (In ₂ O _{3) 50, (ZrO 2)} 25 (SiO 2) 25 (MgO) 50, (ZrO 2) 25 (SiO 2) 25 (Y 2 O 3) 50, and as a comparative example ( _{rO 2) 25 (SiO 2)} 25 (Cr 2 O 3) is 16 kinds of _50.

  A sputtering target containing an oxide-based material (diameter 100 mm, thickness 6 mm) is attached in the vacuum chamber of the sputtering apparatus, and quartz glass (length 18 mm, width 12 mm, thickness 1.2 mm) is opposed to the sputtering target as a substrate. Attached. Sputtering was performed at a power of 400 W using a high frequency power source in an Ar gas atmosphere at a pressure of 0.13 Pa. Each of the 16 types of materials was sputtered under the same conditions, and an oxide-based material layer of 20 nm was formed on each quartz glass substrate. A quartz glass sample piece is taken out of the vacuum chamber, and ellipsometry is used for complex refractive indexes (n-ki, n: refractive index, k: extinction) in the red region (wavelength λ = 660 nm) and the blue-violet region (wavelength λ = 405 nm). Coefficient). Table 3 shows the measurement results.

As shown in Table 3, Samples 1-1 to 1-14 excluding Comparative Example (ZrO ₂ ) ₂₀ (Cr ₂ O ₃ ) ₈₀ and (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ All of the materials had k = 0.00 at λ = 660 nm and λ = 405 nm. That is, it was confirmed to be transparent. It was confirmed that the material containing Cr ₂ O ₃ has 0 <k and low transparency.

  The complex refractive index can also be calculated by measuring the reflectance and transmittance of the sample piece with a spectroscope. Even with this method, the complex refractive index can be obtained with high accuracy.

(Example 2)
When the same oxide-based material layer as in Example 1 was used except that HfO ₂ was included instead of ZrO ₂ , the same result as in Example 1 was obtained. Specifically, (HfO ₂ ) _X1 (E1) _100-X1 (mol%) and (HfO ₂ ) _X1 (SiO ₂ ) _Z (E) _{100-X1 -Z} (mol%) are also expressed as λ = 660 nm and λ K = 0.00 at 405 nm. That is, it was confirmed to be transparent.

(Example 3)
In Example 3, the information recording medium 25 was manufactured using an oxide material layer. Specifically, an oxide material layer made of a material of (ZrO ₂ ) ₅₀ (E) ₅₀ (mol%) was used for the first dielectric layer 2 and the second dielectric layer 6. Incidentally, E be expressed here indicates one of _{La 2 O 3, CeO 2,} Al 2 O 3, Ga 2 O 3, In 2 O 3, MgO, Y 2 O 3. Using such an oxide-based material layer, seven types of medium samples (Samples 3-1 to 3-7) were prepared, and adhesion, repeated rewriting performance, and recording sensitivity were evaluated.

  Hereinafter, a method for producing the information recording medium 25 will be described. In the following description, for ease of understanding, the same reference numbers as those of the components shown in FIG. 1 are used as the reference numbers of the components. Similarly, in the information recording mediums of the embodiments described later, the same reference numbers as the constituent elements in the corresponding information recording medium are used as the reference numbers of the respective constituent elements.

  First, as the substrate 1, a guide groove having a depth of 56 nm and a track pitch (distance between the center of the groove surface and the land surface in a plane parallel to the main surface of the substrate) of 0.615 μm is provided in advance on one surface, and the diameter is 120 mm. A circular polycarbonate substrate having a thickness of 0.6 mm was prepared. On the substrate 1, a first dielectric layer 2 having a thickness of 150 nm, a recording layer 4 having a thickness of 9 nm, a second dielectric layer 6 having a thickness of 50 nm, a light absorption correction layer 7 having a thickness of 40 nm, and a thickness An 80 nm reflective layer 8 was formed in this order by the sputtering method as described below.

In the step of forming the first dielectric layer 2 and the second dielectric layer 6, a sputtering target (diameter 100 mm, thickness 6 mm) made of the aforementioned (ZrO ₂ ) ₅₀ (E) ₅₀ (mol%) material. Was attached to a film forming apparatus, and 400 W high frequency sputtering was performed in an Ar gas atmosphere at a pressure of 0.13 Pa.

In the step of forming the recording layer 4, a sputtering target (diameter: 100 mm, thickness: 6 mm) made of a Ge—Sn—Sb—Te-based material in which part of Ge having a GeTe—Sb ₂ Te ₃ pseudobinary composition is replaced with Sn. ) Was attached to the film forming apparatus, and direct current sputtering was performed. The power was 100W. During sputtering, a mixed gas of Ar gas (97%) and N ₂ gas (3%) was introduced. The pressure during sputtering was 0.13 Pa. The composition of the recording layer was Ge ₂₇ Sn ₈ Sb ₁₂ Te ₅₃ (atomic%).

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 the pressure is about 0.4 Pa. In the Ar gas atmosphere, 300 W DC sputtering was performed.

  In the step of forming the reflective layer 8, a sputtering target (diameter: 100 mm, thickness: 6 mm) made of an Ag—Pd—Cu alloy is attached to the film forming apparatus, and 200 W of 200 W is used in an Ar gas atmosphere at a pressure of about 0.4 Pa. DC sputtering was performed.

  After forming the reflective layer 8, an ultraviolet curable resin was applied on the reflective layer 8. A dummy substrate 10 made of polycarbonate having a diameter of 120 mm and a thickness of 0.6 mm was brought into close contact with the applied ultraviolet curable resin. Next, the resin was cured by irradiating ultraviolet rays from the dummy substrate 10 side. Thereby, the adhesive layer 9 made of a cured resin was formed with a thickness of 30 μm, and at the same time, the dummy substrate 10 was bonded onto the reflective layer 8 via the adhesive layer 9.

  After bonding the dummy substrate 10, an initialization process was performed using a semiconductor laser having a wavelength of 810 nm. In the initialization step, the recording layer 4 located in the annular region having the radius of 22 to 60 mm of the information recording medium 25 was crystallized over almost the entire surface. With the completion of the initialization process, the production of the information recording medium 25 was completed.

As a comparative example, a medium sample (Comparative Example 3-1) in which the first dielectric layer 2 and the second dielectric layer 6 are formed of (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ (mol%) is also produced. did. In the manufacturing process, a sputtering target (diameter: 100 mm, thickness: 6 mm) made of a (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ (mol%) material is attached to a film forming apparatus, and in an Ar gas atmosphere at a pressure of 0.13 Pa. Then, high frequency sputtering of 400 W was performed. The materials and processes of the other layers are the same.

  Next, an evaluation method for the information recording medium will be described. The adhesion of the dielectric layer in the information recording medium 25 was evaluated based on the presence or absence of peeling under high temperature and high humidity conditions. Specifically, the information recording medium 25 after the initialization process is left in a high-temperature and high-humidity tank with a temperature of 90 ° C. and a relative humidity of 80% for 100 hours, and then between the recording layer and the dielectric layer in contact with the recording layer. For example, whether or not peeling has occurred 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 is visually observed using an optical microscope. Examined. As a matter of course, a sample without peeling is evaluated as having good adhesion, and a sample with peeling is evaluated as being poor in adhesion.

  The repeated rewriting performance of the information recording medium 25 was evaluated based on the number of repetitions. The number of repetitions was determined under the following conditions.

  In order to record information on the information recording medium 25, a spindle motor that rotates the information recording medium 25, an optical head that includes a semiconductor laser that emits laser light 12, and the laser light 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 condensing light was used. In the evaluation of the information recording medium 25, recording corresponding to 4.7 GB capacity 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 velocity for rotating the information recording medium 25 was set to 8.2 m / sec. Further, a time interval analyzer was used for measuring the jitter value when obtaining the average jitter value described later.

  First, peak power (Pp) and 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 toward the information recording medium 25 while performing power modulation 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 (3T) to 1.96 μm (14T) was recorded 10 times (by groove recording) on the same groove surface of the recording layer 4. Then, a jitter value between the front ends and a jitter value between the rear ends were measured, and an average jitter value was obtained as an average value of these values. When the average jitter value is measured for each recording condition with the bias power fixed at a fixed value and the peak power is changed variously, and the peak power is gradually increased, and the average jitter value of the random signal reaches 13%. The power of 1.3 times the peak power was temporarily determined as Pp1. Next, the average jitter value is measured for each recording condition with the peak power fixed at Pp1 and the bias power varied, and the upper limit value of the bias power when the average jitter value of the random signal is 13% or less. And the average value of the lower limit was set to Pb. When the bias power is fixed at Pb and the average jitter value is measured for each recording condition with various changes in the peak power, and the peak power is gradually increased, the average jitter value of the random signal reaches 13%. The power of 1.3 times the peak power was set to 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 repeated recording 10 times. Considering the upper limit of the laser power of the system, it is desirable to satisfy Pp ≦ 14 mW and Pb ≦ 8 mW. The recording sensitivity is better when the value of Pp is smaller.

  In this embodiment, the number of repetitions is determined based on the average jitter value. A laser beam is modulated with Pp and Pb set as described above while irradiating the information recording medium 25 with power modulation, and a random signal having a mark length of 0.42 μm (3T) to 1.96 μm (14T) is ( The average jitter value was measured after continuous recording was repeated a predetermined number of times on the same groove surface (by groove recording). The average jitter value is measured when the number of repetitions is 1, 2, 3, 5, 10, 100, 200, and 500 times, and is measured every 1000 times when the number of repetitions is 1000 to 10,000. Was measured every 10,000 times in the range of 20000 to 100,000 times. The time when the average jitter value reached 13% was judged as the limit of repeated rewriting, and the repeated rewriting performance was evaluated based on the number of repetitions. As a matter of course, the larger the number of repetitions, the higher the rewrite performance is evaluated. When the information recording medium is used as an external memory of a computer, the number of repetitions is preferably 100,000 times or more. When the information recording medium is used in an audio / video recorder, the number of repetitions is preferably 10,000 times or more.

As shown in Table 4, Samples 3-1 to 3-7 obtained good adhesion, repeated rewriting performance, and recording sensitivity. In particular, (ZrO ₂ ) ₅₀ (Ga ₂ O ₃ ) ₅₀ (mol%) of Sample No. 3-4 was capable of 100,000 repetition performance and high recording sensitivity of 12.5 mW. On the other hand, the recording sensitivity of the comparative example using the (ZrO ₂ ) ₅₀ (Cr ₂ O ₃ ) ₅₀ (mol%) oxide material layer exceeded 14 mW. From this result, it was confirmed that the recording sensitivity was improved by using an oxide material layer containing a mixture of ZrO ₂ and E.

Further, media similar to Samples 3-1 to 3-7 and Comparative Example 3-1 were prepared except that HfO ₂ was used instead of ZrO ₂ (Sample Nos. 3-11 to 3-17 and Comparative Example 3). -2) When evaluated in the same manner, the results shown in Table 5 below were obtained. From this result, it was confirmed that the recording sensitivity was also improved for the oxide-based material layer containing a material containing HfO ₂ and ( E ).

(Example 4)
In Example 4, the applicable composition range of the (ZrO ₂ ) ₅₀ (Ga ₂ O ₃ ) ₅₀ (mol%) oxide-based material layer that showed particularly good performance in Example 3 was determined. As in Example 3, the oxide-based material layer in which the composition ratio of ZrO ₂ and Ga ₂ O ₃ is changed is applied to the first dielectric layer 2 and the second dielectric layer 6 of the information recording medium 25, respectively. did. The oxide-based material layer used here is expressed as (ZrO ₂ ) _X (Ga ₂ O ₃ ) _100-X (mol%), and 11 types of medium samples formed with oxide-based material layers having different values of X (Samples 4-1 to 4-11) were produced.

  Table 6 shows the evaluation results obtained by evaluating the adhesion, repeatability, and recording sensitivity in the same manner as in Example 3.

As shown in Table 6, information using (ZrO ₂ ) _X (Ga ₂ O ₃ ) _100-X (mol%) oxide-based material layer for the first dielectric layer 2 and the second dielectric layer 6 All of the recording media 25 achieved both good adhesion, repetitive rewriting performance of 100,000 times, and recording sensitivity of less than 14 mW. This result also revealed that (ZrO ₂ ) _X (Ga ₂ O ₃ ) _100-X (mol%) can be used in a wide range of 0 <X <100. The material used in this example can be expressed by the formula (2). Therefore, from this result, it is also clear that the material that can be expressed by the formula (2) can be used in a wide range of 0 <X1 <100.

Furthermore, 11 types of medium samples were similarly prepared for the (HfO ₂ ) ₅₀ (Ga ₂ O ₃ ) ₅₀ (mol%) oxide-based material layer that showed particularly good performance in Example 3 (sample) No. 4-21 to 4-31) and the evaluation was performed.

As shown in Table 7, it was also revealed that (HfO ₂ ) _X (Ga ₂ O ₃ ) _100-X (mol%) can be used in a wide range of 0 <X <100. The material used in this example can be expressed by the formula (4). Therefore, from this result, it was also confirmed that the material that can be represented by the formula (4) can be used in a wide range of 0 <X2 <100.

(Example 5)
In Example 5, (D3) _X3 (SiO ₂ ) _Z1 (E2) _100-X3-Z1 (mol%) oxide-based material layer when SiO ₂ is used as g in the material represented by the formula (7) Was used for the first dielectric layer 2 and the second dielectric layer 6 to produce an information recording medium 25. Specifically, D3 contains ZrO ₂ , and E2 contains La ₂ O ₃ , CeO ₂ , Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , MgO, Y ₂ O ₃ , and X3 = Z = 25. In the step of forming the first dielectric layer 2 and the second dielectric layer 6, a sputtering target made of the above-mentioned (D3) _X3 (SiO ₂ ) _Z (E2) _100-X3-Z (mol%) material. (Diameter 100 mm, thickness 6 mm) was attached to a film forming apparatus, and 400 W high-frequency sputtering was performed in an Ar gas atmosphere at a pressure of 0.13 Pa. The materials and processes of other layers are the same as in Example 3. As a comparative example, a medium sample in which the first dielectric layer 2 and the second dielectric layer 6 are formed of (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (mol%) (Comparative Example 5) -1) was also produced.

In this way, seven types of medium samples (Samples 5-1 to 5-7) were prepared, and adhesion, repeated rewriting performance, and recording sensitivity were evaluated in the same manner as in Example 3. The results are shown in Table 8 .

As shown in Table 8, in Samples 5-1 to 5-7, good results were obtained in terms of adhesion, repeatability, and recording sensitivity. When compared with the results shown in Table 4 of Example 3, it was confirmed that the inclusion of SiO ₂ improved the repetition performance and further improved the recording sensitivity. In particular, Sample 5-4 using an (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₅₀ (mol%) oxide-based material layer has a repeatability exceeding 100,000 times and a recording sensitivity of less than 12 mW. was gotten. In comparison (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (mol%), 14 mW <Pp.

Further, medium samples similar to Samples 5-1 to 5-7 were prepared (sample numbers 5-11 to 5-17) except that HfO ₂ was used as D3, and evaluation was performed in the same manner. Further, as a comparative example, a medium sample in which the first dielectric layer 2 and the second dielectric layer 6 are formed of (HfO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (mol%) (comparison) Example 5-2) was also prepared.

  As shown in Table 9, Samples 5-11 to 5-17 also showed good results in adhesion, repeatability, and recording sensitivity as in Samples 5-1 to 5-7.

(Example 6)
In Example 6, in the information recording medium 26 shown in FIG. 2 corresponding to Embodiment 2 described above, information recording in which the first dielectric layer 2 and the second interface layer 5 are oxide-based material layers. A medium (Sample 6-1) was produced. Hereinafter, a method for producing the information recording medium 26 will be described.

  First, the same substrate as that used in Example 3 was prepared as the substrate 1. On this substrate 1, a first dielectric layer 2 having a thickness of 150 nm, a recording layer 4 having a thickness of 9 nm, a second interface layer 5 having a thickness of 3 nm, a second dielectric layer 106 having a thickness of 50 nm, A light absorption correction layer 7 having a thickness of 40 nm and a reflective layer 8 having a thickness of 80 nm were formed in this order by a sputtering method in the following manner.

In the step of forming the first dielectric layer 2, a (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₅₀ (mol%) sputtering target (diameter 100 mm, thickness 6 mm) is used as a film forming apparatus. Attach and perform high frequency sputtering in an Ar gas atmosphere at a pressure of 0.13 Pa. The power was 400W.

Similar to the first dielectric layer 2, the second interface layer 5 is made of (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₅₀ (mol%) sputtering target (diameter 100 mm, thickness 6 mm). Was attached to the film forming apparatus, and high-frequency sputtering was performed in an Ar gas atmosphere at a pressure of 0.13 Pa. The power was 400W.

The second dielectric layer 106 is formed of Ar gas (97) at a pressure of 0.13 Pa using a sputtering target (diameter 100 mm, thickness 6 mm) made of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%). %) And O ₂ gas (3%) were introduced, and 400 W high frequency sputtering was performed. The recording layer 4, the light absorption correction layer 7 and the reflection layer 8 were formed in the same manner as in Example 3.

As a comparative example, a medium (Comparative Example 6-1) in which the first dielectric layer 2 and the second interface layer 5 are formed of (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (mol%). ) Was also produced. Groove recording and land recording were performed on the manufactured information recording medium 26, and the number of repetitions was determined according to the method described in Example 3 to evaluate repeated rewriting performance. Table 10 shows the evaluation results.

As shown in Table 10, the information recording medium 26 in which the first dielectric layer 2 and the second interface layer 5 are oxide-based material layers also has excellent adhesion in groove recording and land recording, repeated rewriting performance, Achieved peak power and bias power. By using (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₅₀ (mol%), (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (mol%) was used. The recording sensitivity was improved by about 20%.

_{Incidentally, (ZrO 2) 20 (SiO} 2) 60 (Ga 2 O 3) 20 (mol%) consisting, oxide-based material layer of SiO ₂ containing 60 mol% first dielectric layer 2 and the second interface layer When the medium used in 5 was prepared and evaluated, the adhesion of the medium was lowered, and peeling was observed on the outer peripheral portion of the medium. Therefore, the SiO ₂ concentration is preferably 50 mol% or less.

(Example 7)
In Example 7, in the information recording medium 27 shown in FIG. 3 corresponding to Embodiment 3 described above, the information recording in which the first interface layer 3 and the second dielectric layer 6 are oxide-based material layers. A medium (Sample 7-1) was produced. Hereinafter, a method for producing the information recording medium 27 will be described.

  First, the same substrate as that used in Example 1 was prepared as the substrate 1. On this substrate 1, a first dielectric layer 102 having a thickness of 150 nm, a first interface layer 3 having a thickness of 5 nm, a recording layer 4 having a thickness of 9 nm, a second dielectric layer 6 having a thickness of 50 nm, A light absorption correction layer 7 having a thickness of 40 nm and a reflection layer 8 having a thickness of 80 nm were formed in this order by a sputtering method in the following manner.

The first dielectric layer 102 was formed of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%). The first interface layer 3 was formed of (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₅₀ (mol%). The recording layer 4 was formed in the same manner as in Example 3. Therefore, the composition was Ge ₂₇ Sn ₈ Sb ₁₂ Te ₅₃ (atomic%).

The second dielectric layer 6 is formed of (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₅₀ (mol%) sputtering target (diameter 100 mm, thickness 6 mm) in an Ar gas atmosphere. .. High frequency sputtering was performed under a pressure of 13 Pa.

  The light absorption correction layer 7 and the reflection layer 8 were formed in the same manner as those of the information recording medium 25 described in Example 3.

For comparison, a medium (Comparative Example 7-1) in which the first interface layer 3 and the second dielectric layer 6 are made of (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (mol%). ) Was also produced as a comparative example.

  About each obtained sample, the adhesiveness of the dielectric material layer and repeated rewriting performance were evaluated. The evaluation results are shown in Table 11. The evaluation method for the adhesion and the repeated rewrite performance is as described above. However, in this example, the evaluation of adhesion was carried out by examining whether or not peeling occurred between the recording layer 4 and the second dielectric layer 6 in contact therewith.

As shown in Table 11, the information recording medium 27 in which the first interface layer 3 and the second dielectric layer 6 are oxide-based material layers also has excellent adhesion in groove recording and land recording, repeated rewriting performance, Achieved peak power and bias power. By using (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₅₀ (mol%), (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (mol%) was used. The recording sensitivity was improved by about 20%.

(Example 8)
In Example 8, in the information recording medium 28 shown in FIG. 4 corresponding to Embodiment 4 described above, the information recording medium in which the first interface layer 3 and the second interface layer 5 are oxide-based material layers. (Sample 8-1) was produced. Hereinafter, a method for producing the information recording medium 28 will be described.

  First, as the substrate 1, the same substrate as that used in Example 3 was prepared. On a substrate 1, a first dielectric layer 102 having a thickness of 150 nm, a first interface layer 3 having a thickness of 5 nm, a recording layer 4 having a thickness of 9 nm, a second interface layer 5 having a thickness of 3 nm, and a thickness of 50 nm. The second dielectric layer 106, the light absorption correction layer 7 having a thickness of 40 nm, and the reflection layer 8 having a thickness of 80 nm were formed in this order by sputtering.

The first dielectric layer 102 was formed of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%). The second dielectric layer 106 was formed in the same manner.

In the step of forming the first interface layer 3, a sputtering target (diameter: 100 mm, thickness: 6 mm) made of (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₅₀ (mol%) is used as a film forming apparatus. Attach and perform high frequency sputtering in an Ar gas atmosphere at a pressure of 0.13 Pa. The power was 400W. The second interface layer 5 was formed in the same manner.

The recording layer 4 was formed in the same manner as in Example 3. Therefore, the composition was Ge ₂₇ Sn ₈ Sb ₁₂ Te ₅₃ (atomic%). The light absorption correction layer 7 was also formed using Ge ₈₀ Cr ₂₀ (atomic%) in the same manner as in Example 3. The reflective layer 8 was also formed of an Ag—Pd—Cu alloy in the same manner as in Example 3.

For comparison, an information recording medium (Sample 8-1) in which the first interface layer 3 and the second interface layer 5 are formed of (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (mol%). ) As a comparative example. About the obtained sample, adhesiveness and repeated rewriting performance were evaluated. In the evaluation of adhesion, peeling occurred between the recording layer 4 and the interface layer in contact therewith, more specifically, between the recording layer and at least one of the first interface layer 3 and the second interface layer 5. This was done by examining whether there was any. The evaluation of repeated rewriting performance was performed by performing groove recording and land recording, and obtaining the number of times of repeating groove recording and land recording according to the method described in the third embodiment. The evaluation results are shown in Table 12.

  As shown in Table 12, the performance of the sample 8-1 using the oxide-based material layer as an interface layer is about 1 mW lower than that of the comparative example, and the recording sensitivity is improved even when used as an interface layer having a thin film thickness. The effect of improving was confirmed. In addition, adhesion and repeatability were equal to or higher than those of Comparative Example 8-1.

The number of layers constituting the sample 8-1 is the same as that of the conventional information recording medium. Therefore, in Sample 8-1, the effect due to the decrease in the number of layers cannot be obtained. However, when the oxide-based material layer is an interface layer, the interface layer can be formed by sputtering in an atmosphere containing only Ar gas, without depending on reactive sputtering. Accordingly, the ease of manufacturing and stability are maintained, and the transparency is higher than the conventional (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (mol%) material, and the recording sensitivity of the medium. We were able to achieve a performance improvement that improved.

  Further, 14 types of media in which the first interface layer 3 and the second interface layer 5 are formed of the oxide material layer represented by the formula (7), (8), (11), or (12) are used. This was manufactured (mediums 8-11 to 8-24), and each was evaluated in the same manner as the medium 8-1. Table 13 shows the oxide type materials used and the evaluation results. Further, as Comparative Examples 8-2 to 8-5, the oxide-based material layer that does not include E2 among the materials represented by Formula (7), (8), (11), or (12) is used. A medium on which the first interface layer 3 and the second interface layer 5 were formed was also prepared and evaluated in the same manner.

  As shown in Table 13, when the oxide material represented by any one of the formulas (7) is used as the interface layer, the recording sensitivity is good, and the adhesiveness and repeated rewriting performance are equal to or higher than those of the comparative example. there were.

Example 9
As Example 9, the examples of the oxide-based material layers containing ZrO ₂ and any one of La ₂ O ₃ , CeO ₂ , Al ₂ O ₃ , In ₂ O ₃ , MgO, and Y ₂ O ₃ are also used. And 8 were performed, good adhesion and repeatability could be obtained, and the recording sensitivity was also good.

(Example 10)
As Example 10, an oxide material layer containing HfO ₂ and any one of La ₂ O ₃ , CeO ₂ , Al ₂ O ₃ , Ga ₂ O ₃ , In ₂ O ₃ , MgO and Y ₂ O ₃ was also used. When Examples 6, 7 and 8 were carried out, good adhesion and repeatability could be obtained, and the recording sensitivity was also good.

As described above, the oxide-based material layer has the configuration of the information recording medium 25 shown in FIG. 1, the configuration of the information recording medium 26 shown in FIG. 2, the configuration of the information recording medium 27 shown in FIG. 3, and the configuration shown in FIG. The configuration of the information recording medium 28 can be used as a dielectric layer or an interface layer, and compared with the case of using the conventional (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (Cr ₂ O ₃ ) ₅₀ (mol%). The recording sensitivity can be improved without deteriorating adhesion and repeatability. Furthermore, at least if used as the first dielectric layer 2 or the second dielectric layer 6, as compared with the structure of a conventional information recording medium 31 shown in FIG. 12, six layers the number of layers seven layers or It is possible to reduce to 5 layers. Regardless of reactive film formation, the film formation conditions are small and the film formation conditions can be optimized faster. Therefore, by using the oxide-based material layer as a dielectric layer or an interface layer, there is also an effect that the mass production start-up of the information recording medium proceeds faster.

(Example 11)
In Example 11, in the information recording medium 29 shown in FIG. 5 corresponding to Embodiment 5 described above, the information recording medium (where the first and second dielectric layers 2 and 6 are oxide material layers) Sample 11-1) was prepared. Hereinafter, a method for producing the information recording medium 29 will be described.

  First, as substrate 101, a guide groove having a depth of 21 nm and a track pitch (distance between 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, diameter 120 mm. A circular polycarbonate substrate having a thickness of 1.1 mm was prepared.

  On the substrate 101, a reflective layer 8 having a thickness of 80 nm, a second dielectric layer 6 having a thickness of 16 nm, a recording layer 4 having a thickness of 10 nm, and a first dielectric layer 2 having a thickness of 68 nm are sputtered in this order. The film was formed by the method described below.

The reflective layer 8 was formed in the same manner as in Example 1. In the step of forming the second dielectric layer 6, a sputtering target (diameter: 100 mm, thickness: 6 mm) made of (ZrO ₂ ) ₃₅ (SiO ₂ ) ₃₅ (Ga ₂ O ₃ ) ₃₀ (mol%) is formed. Attached to the apparatus, high-frequency sputtering was performed in an Ar gas atmosphere at a pressure of 0.13 Pa. The power was 400W. The first dielectric layer 2 was formed in the same manner.

In the step of forming the recording layer 4, a sputtering target (diameter: 100 mm, thickness: 6 mm) made of a Ge—Bi—Te-based material was attached to the film forming apparatus, and direct current sputtering was performed. The power was 100W. During sputtering, a mixed gas of Ar gas (97%) and N ₂ gas (3%) was introduced. The pressure during sputtering was about 0.13 Pa. The composition of the recording layer 4 was Ge ₄₅ Bi ₄ Te ₅₁ .

  After forming the first dielectric layer 2, an ultraviolet curable resin was applied on the first dielectric layer 2. A circular polycarbonate substrate having a diameter of 120 mm and a thickness of 90 μm was adhered as a dummy substrate 110 on the applied ultraviolet curable resin. Next, the resin was cured by irradiating ultraviolet rays from the dummy substrate 110 side. As a result, the adhesive layer 9 made of cured resin was formed to a thickness of 10 μm, and at the same time, the dummy substrate 110 was bonded onto the first dielectric layer 2 via the adhesive layer 9.

  After bonding the dummy substrate 110, an initialization process was performed using a semiconductor laser having a wavelength of 670 nm. In the initialization process, the recording layer 4 located in the annular region having the radius of 22 mm to 60 mm of the information recording medium 29 was crystallized over almost the entire surface. The production of the information recording medium 29 (Sample 11-1) was completed by the end of the initialization process. The manufactured information recording medium 29 had a measured Rc value of 20% (on a flat surface having no irregularities) and a measured value of Ra of 2%.

As a comparative example, (ZrO ₂ ) ₃₅ (SiO ₂ ) ₃₅ (Cr ₂ O ₃ ) ₃₀ (mol%) material is used for the first dielectric layer 2 and the second dielectric layer 6, and other materials are: An information recording medium (Comparative Example 11-1) similar to the information recording medium 29 was produced.

About each obtained sample, adhesiveness and repeated rewriting performance were evaluated. The evaluation results are shown in Table 14 . The method for evaluating adhesion is as described in Example 1. The repeated rewriting performance was evaluated by a method different from the method employed in Example 1. The method will be described below.

  The repeated rewriting performance of the information recording medium 29 was evaluated using an information recording system having the same configuration as that used in Example 1. In the evaluation of the information recording medium 29, recording corresponding to a capacity of 25 GB was performed using a semiconductor laser having a wavelength of 405 nm and an objective lens having a numerical aperture of 0.85. The linear velocity for rotating the information recording medium 29 was 4.92 m / sec (data transfer rate: 36 Mbps) and 9.84 m / sec (72 Mbps). A time interval analyzer was used to measure the jitter value when obtaining the average jitter value (average value of the jitter between the front end and the back end jitter).

  First, peak power (Pp) and 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 toward the information recording medium 29 while performing power modulation between a peak power (mW) at a high power level and a bias power (mW) at a low power level, and 2T having a mark length of 0.149 μm. The signal was recorded 10 times on the same groove surface of the recording layer 4. After recording 2T to 8T random signals 10 times, the average jitter value was measured. When the random signal is recorded 10 times, the bias power is fixed to a constant value, the average jitter value is measured for each recording condition with various peak power changes, and the peak power at which the average jitter value becomes the minimum value is set to Pp1. Set. The average jitter value was measured for each recording condition with the peak power fixed at Pp1 and the bias power varied, and the bias power at which the average jitter value became the minimum value was set to Pb. Again, the bias power was fixed at Pb, the average jitter value was measured for each recording condition with various peak power changes, and the peak power at which the average jitter value was the minimum value was set to Pp. It is desirable that the obtained Pp and Pb satisfy 5.2 mW or less at 36 Mbps in consideration of the standard. Considering the balance with the system even at 72 Mbps, it is desirable to satisfy 6 mW or less.

  In this embodiment, the number of repetitions is determined based on the average jitter value. Laser light was irradiated to the information recording medium 29 while power-modulating with Pp and Pb set as described above, and random signals were repeatedly recorded on the same groove surface a predetermined number of times. Then, the average jitter value was measured. The average jitter value was obtained when the number of repetitions was 1, 2, 3, 5, 10, 100, 200, 500, 1000, 2000, 3000, 5000, 7000, and 10,000 times. Based on the average jitter value when repeated 10 times, when the average jitter value increased by 3% was judged as the limit of repeated rewriting, and the repeated rewriting performance was evaluated by the number of repetitions at this time. Naturally, the larger the number of repetitions, the higher the repeated rewriting performance. The number of repetitions of the information recording medium 29 is preferably 10,000 times or more.

The information recording medium 29 of the sample 11-1 of this example is different from the information recording medium 25 shown in FIG. 1 in the order in which each layer is formed on the substrate, recording conditions (laser wavelength and numerical aperture of the lens), and recording. The capacity is different. The recording capacity of the sample 11-1 is five times or more that of the information recording medium 25 shown in FIG. However, regardless of these differences, as shown in Table 14 , as the first dielectric layer 2 and the second dielectric layer 6, (ZrO ₂ ) ₃₅ (SiO ₂ ) ₃₅ (Ga ₂ O ₃ ) _{By using a 30} (mol%) oxide material layer, a recording sensitivity satisfying the standard was obtained with a capacity of 25 GB. In the comparative example, the recording sensitivity was not satisfactory.

In the configuration of the information recording medium 29, even when only the first dielectric layer 2 or the second dielectric layer 6 is an oxide-based material layer, similar results were obtained. That is, by using an oxide-based material layer, the interface layer required when (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) is used can be reduced at least further, and equivalent performance can be ensured. can do. In addition, since the oxide-based material layer employed in the present invention does not contain S (sulfur), atomic diffusion does not occur even when the interface is in contact with the reflective layer 8 containing Ag. As a result, a four-layer configuration is possible. As a matter of course, a layer for adjusting light absorption / reflection in the recording layer may be formed between the reflective layer 8 and the second dielectric layer 6 as necessary. Such a layer is formed of one material or a mixture of two or more materials selected from metals, non-metals, metalloids, semiconductors and dielectrics, and compounds thereof. Such a layer preferably has a refractive index of 4 or less and an extinction coefficient of 4 or less for light in the vicinity of a wavelength of 405 nm.

Example 12
In Example 12, in the information recording medium 30 shown in FIG. 6 corresponding to Embodiment 6 described above, the fifth dielectric layer 19, the fourth dielectric layer 17, the second dielectric layer 6, and An information recording medium (Sample 12-1) in which the first dielectric layer 2 was an oxide-based material layer was produced. Hereinafter, a method for producing the information recording medium 30 will be described.

  First, the same substrate as the substrate 101 used in Example 11 was prepared as the substrate 101. On the substrate 101, a second reflective layer 20 having a thickness of 80 nm, a fifth dielectric layer 19 having a thickness of 16 nm, a second recording layer 18 having a thickness of 10 nm, and a fourth dielectric layer 17 having a thickness of 68 nm. The second information layer 22 was formed in this order by sputtering.

The second reflective layer 20 was formed of an Ag—Pd—Cu alloy in the same manner as in Example 1. In the step of forming the fifth dielectric layer 19, a sputtering target (diameter 100 mm, thickness 6 mm) made of (ZrO ₂ ) ₃₅ (SiO ₂ ) ₃₅ (Ga ₂ O ₃ ) ₃₀ (mol%) is formed. Attached to the apparatus, high-frequency sputtering was performed in an Ar gas atmosphere at a pressure of 0.13 Pa. The power was 400W. The fourth dielectric layer 17 was formed in the same manner. The second recording layer 18 was formed using a sputtering target made of a Ge—Bi—Te-based material in the same manner as in Example 11.

  Next, an intermediate layer 16 having a groove and a thickness of 25 μm was formed on the second information layer 22. The intermediate layer 16 was formed according to the following procedure. First, an ultraviolet curable resin was applied by spin coating. On the applied ultraviolet curable resin, a polycarbonate substrate having irregularities on its surface was placed in close contact with the irregularities. The unevenness had a shape complementary to the guide groove to be formed in the intermediate layer 16. Thereafter, the resin was cured by irradiating ultraviolet rays from the polycarbonate substrate side, and the polycarbonate substrate was peeled off from the intermediate layer 16. As a result, an intermediate layer 16 in which the guide groove was formed by transfer, obtained by curing the ultraviolet curable resin, was obtained.

  After the formation of the intermediate layer 16, an initialization process for the second information layer 22 was performed. In the initialization step, the second recording layer 18 located in the annular region having a radius of 22 mm to 60 mm was crystallized over almost the entire surface using a semiconductor laser having a wavelength of 670 nm.

  Next, a third dielectric layer 15 having a thickness of 15 nm, a first reflective layer 14 having a thickness of 10 nm, a second dielectric layer 6 having a thickness of 12 nm, and a first dielectric layer having a thickness of 6 nm are formed on the intermediate layer 16. The recording layer 13 and the first dielectric layer 2 having a thickness of 45 nm were formed in this order by the sputtering method to form the first information layer 21.

In the step of forming the third dielectric layer 15, high-frequency sputtering was performed at a pressure of about 0.13 Pa using a sputtering target (diameter 100 mm, thickness 6 mm) made of TiO ₂ . The power was 400W. During sputtering, a mixed gas of Ar gas (97%) and O ₂ gas (3%) was introduced.

The first reflective layer 14 was also formed in the same manner as the second reflective layer 20, and was formed as an Ag—Pd—Cu alloy layer. The second dielectric layer 6 and the first dielectric layer 2 were formed of (ZrO ₂ ) ₅₆ (SiO ₂ ) ₁₄ (Ga ₂ O ₃ ) ₃₀ (mol%).

In the step of forming the first recording layer 13, a sputtering target (diameter: 100 mm, thickness: 6 mm) made of a Ge—Sn—Bi—Te-based material is attached to a film forming apparatus, and a direct current is applied at a pressure of 0.13 Pa. Sputtering was performed. The power was 50W. Ar gas (100%) was introduced during sputtering. The pressure during sputtering was about 0.13 Pa. The composition of the recording layer was Ge ₄₀ Sn ₅ Bi ₄ Te ₅₁ (atomic%).

  After forming the first dielectric layer 2, an ultraviolet curable resin was applied on the first dielectric layer 2. A circular polycarbonate substrate having a diameter of 120 mm and a thickness of 65 μm was brought into close contact with the applied ultraviolet curable resin as a dummy substrate 110. Next, the resin was cured by irradiating ultraviolet rays from the dummy substrate 110 side. As a result, the adhesive layer 9 made of cured resin was formed to a thickness of 10 μm, and at the same time, the dummy substrate 110 was bonded onto the first dielectric layer 2 via the adhesive layer.

  After bonding the dummy substrate 110, the initialization process of the first information layer 21 was performed using a semiconductor laser having a wavelength of 670 nm. In the initialization step, the first recording layer 13 located in the annular region having a radius of 22 mm to 60 mm was crystallized over substantially the entire surface. The production of the information recording medium 30 (sample 12-1) was completed by the end of the initialization process.

For each of the first information layer 21 and the second information layer 22 of the sample 12-1, the adhesion of the dielectric layer and the repeated rewriting performance of the information recording medium were evaluated. These results are shown in Table 15 together with the peak power (Pp) and bias power (Pb) obtained in the evaluation of the repeated rewrite performance.

  In this example, the adhesion of the dielectric layer was evaluated under the same conditions as in Example 1 by examining whether each of the first information layer 21 and the second information layer 22 was peeled off. The evaluation of the repetitive rewriting performance of the information recording medium 30 is performed by performing recording corresponding to a 25 GB capacity on each of the first information layer 21 and the second information layer 22 under the same conditions as those in the eleventh embodiment. And the number of repetitions for each of the second information layers 22 were examined. When recording on the first information layer 21, the laser beam 12 is focused on the first recording layer 13, and when recording the second information layer 22, the laser beam 12 is focused on the second recording layer 18. I let you. Considering the balance with the standard and the system, it is desirable that the first information layer 21 satisfies Pp ≦ 10.4 mW at 36 Mbps.

The information recording medium 30 of the sample 12-1 of this example is different from the information recording medium 25 shown in FIG. 1 in that the order of formation of each layer on the substrate and the number of information layers (that is, recording layers) are two. And recording conditions (laser wavelength and lens numerical aperture) are different. The recording capacity of the sample 12-1 is about 10 times that of the information recording medium 25 shown in FIG. However, regardless of these differences, the first, second, fourth and fifth dielectric layers ₂ , 6, 17 and 19 are layers made of a mixture of ZrO ₂ , SiO ₂ and Ga ₂ O _3. By using it, it was confirmed that an information recording medium having good performance can be obtained without providing an interface layer. The Rc design value of the first information layer 21 (in the flat surface portion having no irregularities) of the manufactured information recording medium 30 was 6%, and the Ra design value was 0.7%. The Rc design value of the second information layer 22 was 25%, and the Ra design value was 3%.

In the present embodiment, the first, second, fourth and fifth dielectric layers 2, 6, 17 and 19 constituting the information recording medium 30 are all oxide-based material layers. It is not limited to this. In one modification, in the information recording medium of the present invention, at least one of these four dielectric layers is an oxide-based material layer, and the other dielectric layer is (ZnS) ₈₀ (SiO ₂ ) ₂₀ ( mol%). In that case, it is necessary to form an interface layer between the (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) dielectric layer and the recording layer. Also in the information recording medium of this modification, the object of reducing the number of layers was achieved, and good performance was obtained as in the sample 12-1.

  In this embodiment, the first and second, fourth and fifth dielectric layers 2 and 6, 17 and 19 are oxide material layers having the same composition. However, the present invention is not limited to this. Not. As a modification, the information recording medium 30 in which these four dielectric layers have different compositions may be manufactured. Such an information recording medium also exhibits good performance, similar to the sample 12-1.

(Example 13)
In Example 13, an oxide of an essential element (for example, in the case of the oxide-based material layer (I) above, an oxide of Zr and an oxide of the element L1, or in the case of the oxide-based material layer (II) above of M1 Evaluation of the performance of an information recording medium having an oxide material layer containing a third component other than the oxides and oxides of the element L2 (the same applies to the oxide material layers of (III) and (IV) above)) . In this example, an information recording medium 27 shown in FIG. 3 was produced in the same manner as in Example 7 except for the material of the second dielectric layer 6.

In forming the second dielectric layer 6, a sputtering target (diameter 100 mm, thickness 6 mm) made of (ZrO ₂ ) ₃₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₄₀ (mol%) is used as a film forming apparatus. Further, Si ₃ N ₄ , Ge, and C sputtering chips each having dimensions of 10 mm × 10 mm × 1 mm were placed on the surface of the sputtering target. Using the sputtering target having this sputtering chip, high-frequency sputtering was performed in an Ar gas atmosphere at a pressure of 0.13 Pa to form the second dielectric layer 6. The power was 400W. When the formed layer was analyzed, the layer contained 98 mol% of (ZrO ₂ ) ₃₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₄₀ (mol%), and Si ₃ N ₄ was contained as the third component. 1 mol%, Ge 0.5 mol%, and C 0.5 mol% were contained.

For comparison, (ZrO ₂ ) ₃₅ (SiO ₂ ) ₂₅ (Ga ₂ O ₃ ) ₄₀ (mol%) not containing the third component was formed in the second dielectric layer 6 (Comparative Example 13-1). . Other materials are the same as the information recording medium 27 of the present embodiment. The adhesion of the second dielectric layer 6 of each sample was evaluated under the same conditions as in Example 1. Further, the repeated rewriting performance of each sample was evaluated by performing groove recording and land recording on each sample, and obtaining the number of times of repeating groove recording and land recording according to the method described in Example 1. As a result, even when an oxide material layer containing 2 mol% of the third component was used, performance satisfying Pp ≦ 14 mW was obtained. The evaluation results are shown in Table 16.

  As shown in Table 16, Sample 13-1 exhibited the same degree of adhesion and repeated rewriting performance as the comparative sample. Moreover, although Pp and Pb of the sample 13-1 were higher than the comparative sample, they satisfied Pp ≦ 14 mW and Pb ≦ 7 mW and were sufficiently practical. From this result, when the dielectric layer contains 98 mol% or more of the oxide of the element selected from the group GM and the oxide of the element selected from the group GL, good adhesion and good repetitive rewriting It was confirmed that performance and good recording sensitivity were ensured.

(Example 14)
In the above Examples 1 to 13, information recording media for recording information by optical means were produced. In Example 14, an information recording medium 207 for recording information by electrical means as shown in FIG. 9 was produced. This 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. On this substrate 201, an Au lower electrode 202 was formed in an area of 1.0 mm × 1.0 mm with a thickness of 0.1 μm. On the lower electrode 202, a phase change portion 205 of Ge ₃₈ Sb ₁₀ Te ₅₂ (which is expressed as Ge ₈ Sb ₂ Te ₁₁ as a compound) is formed in a circular region having a diameter of 0.2 mm to have a thickness of 0.1 μm. And the heat insulating portion 206 of (ZrO ₂ ) ₁₅ (SiO ₂ ) ₁₅ (Ga ₂ O ₃ ) ₇₀ (mol%) is formed in a region of 0.6 mm × 0.6 mm (excluding the phase change portion 205). The thickness is the same as that of the phase change portion 205. Further, an upper electrode 204 of Au was formed in a region of 0.6 mm × 0.6 mm with a thickness of 0.1 μm. The lower electrode 202, the phase change part 205, the heat insulating part 206, and the upper electrode 204 were all formed by sputtering.

In the process of forming the phase change unit 205, a sputtering target (diameter 100 mm, thickness 6 mm) made of a Ge—Sb—Te-based material is attached to the film forming apparatus, and Ar gas is introduced at a power of 100 W to perform direct current sputtering. went. The pressure during sputtering was about 0.13 Pa. In the step of forming the heat insulating portion 206, a sputtering target (diameter: 100 mm, thickness: 6 mm) made of a material having a composition of (ZrO ₂ ) ₁₅ (SiO ₂ ) ₁₅ (Ga ₂ O ₃ ) ₇₀ (mol%). Was attached to a film forming apparatus, and high-frequency sputtering was performed under a pressure of about 0.13 Pa. The power was 400W. Ar gas was introduced during sputtering. Sputtering in these steps was performed by covering the region other than the surface to be formed with a mask jig so that the phase change portion 205 and the heat insulating portion 206 were not stacked on each other. Regardless of the order of formation of the phase change part 205 and the heat insulating part 206, either may be performed first.

  The phase change unit 205 and the heat insulating unit 206 constitute a recording unit 203. The phase change portion 205 corresponds to the recording layer according to the present invention, and the heat insulating portion 206 corresponds to the oxide material layer according to the present invention.

  Since the lower electrode 202 and the upper electrode 204 can be formed by a sputtering method generally employed in the field of electrode formation technology, detailed description of these film forming steps is omitted.

  It was confirmed by the system shown in FIG. 10 that a phase change occurred in the phase change unit 205 by applying electrical energy to the information recording medium 207 manufactured as described above. The cross-sectional view of the information recording medium 207 shown in FIG. 10 shows a cross section of the information recording medium 207 shown in FIG. 9 cut in the thickness direction along line AB.

  More specifically, as shown in FIG. 10, by bonding two application units 212 to the lower electrode 202 and the upper electrode 204 with Au lead wires, the electric writing / reading device 214 is connected via the application unit 212. An information recording medium (memory) 207 was connected. In the electrical writing / reading device 214, a pulse generator 208 is connected via a switch 210 between the application units 212 connected to the lower electrode 202 and the upper electrode 204, respectively, and the resistance measuring device 209 is connected. Are connected via the switch 211. The resistance measuring device 209 is connected to the determination unit 213 that determines whether the resistance value measured by the resistance measuring device 209 is high or low. The pulse generator 208 causes a current pulse to flow between the upper electrode 204 and the lower electrode 202 via the application unit 212, and the resistance value between the lower electrode 202 and the upper electrode 204 is measured by the resistance measuring device 209. The determination unit 213 determined whether the value was high or low. In general, since the resistance value changes due to the phase change of the phase change unit 205, the phase state of the phase change unit 205 can be known based on the determination result.

  In this example, 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 portion 205 was in an amorphous phase state, and 20Ω when the phase change portion 205 was in a crystalline phase state. When the phase change portion 205 is in an amorphous phase state (that is, 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 as a result, between the lower electrode 202 and the upper electrode 204. As a result, the phase change portion 205 changed from an amorphous phase state to a crystalline phase state. Next, when the phase change portion 205 is in a crystalline phase state (that is, a low resistance state), a current pulse of 200 mA, 100 ns is applied between the lower electrode 202 and the upper electrode 204. In the meantime, the resistance value increased, and the phase change portion 205 changed from the crystalline phase to the amorphous phase.

From the above results, a layer containing a material having a composition of (ZrO ₂ ) ₁₅ (SiO ₂ ) ₁₅ (Ga ₂ O ₃ ) ₇₀ (mol%) is used as the heat insulating part 206 around the phase change part 205, and By applying energy, it was possible to cause a phase transformation 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 this embodiment, when a heat insulating portion 206 of (ZrO ₂ ) ₁₅ (SiO ₂ ) ₁₅ (Ga ₂ O ₃ ) ₇₀ (mol%) as a dielectric is provided around the cylindrical phase change portion 205. By applying a voltage between the upper electrode 204 and the lower electrode 202, it is possible to effectively suppress the current flowing through the phase change portion 205 from escaping to the periphery thereof. As a result, the temperature of the phase change unit 205 can be efficiently increased by Joule heat generated by current. In particular, when the phase change portion 205 is changed to an amorphous phase state, a process of once melting and quenching the Ge ₃₈ Sb ₁₀ Te ₅₂ of the phase change portion 205 is necessary. This melting of the phase change portion 205 can occur with a smaller current by providing a heat insulating portion 206 around the phase change portion 205.

Since (ZrO ₂ ) ₁₅ (SiO ₂ ) ₁₅ (Ga ₂ O ₃ ) ₇₀ (mol%) in the heat insulating portion 206 has a high melting point and is less likely to cause atomic diffusion due to heat, It can be applied to memory. Further, when the heat insulating portion 206 exists around the phase change portion 205, the heat insulating portion 206 serves as a barrier, and the phase change portion 205 is substantially electrically and thermally isolated in the plane of the recording portion 203. Utilizing this, the information recording medium 207 is provided with a plurality of phase change units 205 separated from each other by the heat insulating unit 206 to increase the memory capacity of the information recording medium 207, and the access function and switching function Can be improved. Alternatively, a plurality of information recording media 207 themselves can be connected.

As an example, (ZrO ₂ ) ₁₅ (SiO ₂ ) ₁₅ (Ga ₂ O ₃ ) ₇₀ (mol%) was used, but D contained ZrO ₂ , and E contained La ₂ O ₃ , CeO ₂ , and Al ₂ O, respectively. Similar results were obtained for oxide-based material layers containing ₃ , In ₂ O ₃ , MgO, and Y ₂ O ₃ . Also includes HfO2 as D, respectively La ₂ O ₃ as _{E, CeO 2, Al 2 O} 3, Ga 2 O 3, In 2 O 3, MgO, for even the oxide-based material layer containing Y ₂ O _3, Similar results were obtained. As described above, the information recording medium of the present invention has been described through various embodiments, and the oxide-based material layer is used for both the information recording medium for recording by optical means and the information recording medium for recording by electric means. be able to. According to the information recording medium of the present invention including this oxide-based material layer, a configuration that has not been realized can be realized and / or a performance superior to that of a conventional information recording medium can be obtained.

  The information recording medium and the manufacturing method thereof according to the present invention include an excellent dielectric material, and as a large-capacity optical information recording medium, a DVD-RAM disk, a DVD-RW disk, a DVD + RW disk, a DVD-R disk, Blu -Useful for ray discs and the like. It can also be applied to magneto-optical disks. Furthermore, it is also useful as an electrical switching element as an electrical information recording medium. Both can be applied to both rewritable and write-once forms, and can be used for information recording media including read-only media.

It is a fragmentary sectional view which shows an example of the information recording medium of this invention. It is a fragmentary sectional view which shows another example of the information recording medium of this invention. It is a fragmentary sectional view which shows another example of the information recording medium of this invention. It is a fragmentary sectional view which shows another example of the information recording medium of this invention. It is a fragmentary sectional view which shows another example of the information recording medium of this invention. It is a fragmentary sectional view which shows another example of the information recording medium of this invention. It is a triangular figure which shows the composition range of the material represented by Formula (1) or (3) of an example of this invention. It is a triangular figure which shows the composition range of the material represented by Formula (19) of an example of this invention. It is a schematic diagram which shows an example of the information recording medium of this invention on which information is recorded by application of an electrical energy. It is a schematic diagram which shows an example of the system which uses the information recording medium shown in FIG. It is the schematic which shows an example of the sputtering device used in the manufacturing method of the information recording medium of this invention. It is a fragmentary sectional view which shows an example of the conventional information recording medium.

Explanation of symbols

1, 101, 201 Substrate 2,102 First dielectric layer 3,103 First interface layer 4 Recording layer 5,105 Second interface layer 6,106 Second dielectric layer 7 Light absorption correction layer 8 Reflection Layer 9 Adhesive layer 10, 110 Dummy substrate 12 Laser beam 13 First recording layer 14 First reflective layer 15 Third dielectric layer 16 Intermediate layer 17 Fourth dielectric layer 18 Second recording layer 19 5th Dielectric layer 20 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 32 Exhaust port 33 Gas supply Port 34 Anode 35 Substrate 36 Sputtering target 37 Cathode 38 Power supply 39 Vacuum vessel 202 Lower electrode 203 Recording unit 204 Upper electrode 205 Phase change unit (recording layer)
206 Heat insulation part (dielectric layer)
208 Pulse generator 209 Resistance measuring device 210, 211 Switch 212 Application unit 213 Determination unit 214 Electrical writing / reading device

Claims (44)

An information recording medium that enables at least one of recording and reproduction of information by light irradiation or application of electrical energy,
And Zr, La, viewed it contains at least one element selected from the group GL1 consisting of Ga and In, an oxide-based material layer containing oxygen (O), in
The oxide material layer has the following formula:
Zr _Q1 L1 _T1 O _100-Q1-T1 (Atom%)
(In the formula, L1 represents at least one element selected from the group GL1, and Q1 and T1 satisfy 0 <Q1 <34, 0 <T1 <50, 20 <Q1 + T1 <60). An information recording medium comprising a material . The information recording medium according to claim 1 , wherein the L1 is Ga. The oxide material layer has the following formula:
(D1) _X1 (E1) _100-X1 (mol%)
(Wherein D1 represents an oxide of Zr, E1 represents an oxide of at least one element selected from the group GL1, and X1 satisfies 0 <X1 <100). The information recording medium according to claim 1 . Wherein D1 is ZrO _2, the information recording medium according to claim 3 wherein E1 is Ga ₂ O _3. An information recording medium that enables at least one of recording and reproduction of information by irradiation of light or application of electrical energy, and M1 (where M1 is a mixture of Zr and Hf or Hf). , La, seen containing Ce, Al, Ga, in, and at least one element selected from the group GL2 consisting of Mg and Y, an oxide-based material layer containing oxygen (O), in
The oxide material layer has the following formula:
M1 _Q2 L2 _T2 O _100-Q2-T2 (Atom%)
(In the formula, M1 represents a mixture of Zr and Hf or Hf, L2 represents at least one element selected from the group GL2, and Q2 and T2 are 0 <Q2 <34, 0 <T2 <50, 20 <Q2 + T2 <60 is satisfied.) An information recording medium comprising the material represented by The information recording medium according to claim 5 , wherein the L2 is Ga. The oxide material layer has the following formula:
(D2) _X2 (E2) _100-X2 (mol%)
(Wherein D2 represents the oxide of M1, E2 represents an oxide of at least one element selected from the group GL2, and X2 satisfies 0 <X2 <100). The information recording medium according to claim 5 , comprising: The information recording medium according to claim 7 , wherein the E2 is Ga ₂ O ₃ . An information recording medium that enables at least one of information recording and reproduction by irradiation of light or application of electrical energy, wherein at least one element selected from the group GM2 consisting of Zr and Hf, and La, Ce , Al, seen containing Ga, in, and at least one element selected from the group GL2 consisting of Mg and Y, Si and the oxide-based material layer containing oxygen (O), in
The oxide material layer has the following formula:
M2 _Q3 Si _R1 L2 _T3 O _100-Q3-R1-T3 (Atom%)
(In the formula, M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and Q3, R1, and T3 are 0 <Q3 ≦ 32, 0 <R1. ≦ 32, 3 <T3 <43, 20 <Q3 + R1 + T3 <60) .   An information recording medium that enables at least one of information recording and reproduction by irradiation of light or application of electrical energy, wherein at least one element selected from the group GM2 consisting of Zr and Hf, and La, Ce And an oxide-based material layer containing at least one element selected from the group GL2 consisting of Al, Ga, In, Mg, and Y, Si, and oxygen (O).
  The oxide material layer further includes at least one element selected from the group GK1 consisting of carbon (C), nitrogen (N), and Cr,
  The oxide material layer has the following formula:
  M2 _Q3 Si _R1 L2 _T3 K1 _J1 O _{100-Q3-R1-T3-J1} (atom%)
(Wherein M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, K1 represents at least one element selected from the group GK1, Q3 , R1, T3 and J1 satisfy the following condition: 0 <Q3 ≦ 32, 0 <R1 ≦ 35, 2 <T3 ≦ 40, 0 <J1 ≦ 40, 20 <Q3 + R1 + T3 + J1 <80. Medium. The information recording medium according to claim 9 or 10 , wherein the M2 is Zr and the L2 is Ga. The oxide material layer has the following formula:
(D3) _X3 (g) _Z1 (E2) _100-X3-Z1 (mol%)
Wherein D3 represents an oxide of at least one element selected from the group GM2, g represents at least one compound selected from the group consisting of SiO ₂ , Si ₃ N ₄ and SiC, and E2 represents the group An oxide of at least one element selected from GL2, wherein X3 and Z1 include a material that can be represented by 10 ≦ X3 <90, 0 <Z1 ≦ 50, 10 <X3 + Z1 ≦ 90). 9. The information recording medium according to 9 or 10 . The oxide material layer has the following formula:
_{(D3) X3 (SiO 2)} Z2 (f) A1 (E2) 100-X3-Z2-A1 (mol%)
(Wherein D3 represents an oxide of at least one element selected from the group GM2, f represents at least one compound selected from the group consisting of SiC, Si ₃ N ₄ and Cr ₂ O ₃ , and E2 represents An oxide of at least one element selected from the group GL2, wherein X3, Z2 and A1 satisfy 10 ≦ X3 <90, 0 <Z2 ≦ 50, 0 <A1 ≦ 50, 10 <X3 + Z2 + A1 ≦ 90) The information recording medium according to claim 10 , comprising a material that can be represented by: An information recording medium that enables at least one of information recording and reproduction by irradiation of light or application of electrical energy, wherein at least one element selected from the group GM2 consisting of Zr and Hf, and La, Ce And an oxide-based material layer containing at least one element selected from the group GL2 consisting of Al, Ga, In, Mg and Y, Cr, and oxygen (O) .
The oxide material layer has the following formula:
M2 _Q4 Cr _U L2 _T4 O _100-Q4-U-T4 (Atom%)
(In the formula, M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and Q4, U, and T4 are 0 <Q4 ≦ 32, 0 <U ≦ 25, 0 <T4 ≦ 40, 20 <Q4 + U + T4 <60 is satisfied)). An information recording medium that enables at least one of information recording and reproduction by irradiation of light or application of electrical energy, wherein at least one element selected from the group GM2 consisting of Zr and Hf, and La, Ce And an oxide-based material layer containing at least one element selected from the group GL2 consisting of Al, Ga, In, Mg and Y, Cr, and oxygen (O).
  The oxide material layer has the following formula:
  M2 _Q4 Cr _U L2 _T4 Si _R2 K2 _J2 O _{100-Q4-U-T4-R2-J2} (atom%)
(In the formula, M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and K2 represents a group GK2 composed of nitrogen (N) and carbon (C)). At least one element selected, Q4, U, T4, R2 and J2 are 0 <Q4 ≦ 32, 0 <U ≦ 25, 0 <T4 ≦ 40, 0 <R2 ≦ 30, 0 <J2 ≦ 40, 25 <Q4 + U + T4 + R2 + J2 <85 is satisfied)). The information recording medium according to claim 14 or 15 , wherein the M2 is Zr and the L2 is Ga. The oxide material layer has the following formula:
(D3) _X4 (Cr ₂ O ₃ ) _A2 (E2) _100-X4-A2 (mol%)
(Wherein D3 represents an oxide of at least one element selected from the group GM2, E2 represents an oxide of at least one element selected from the group GL2, and X4 and A2 are 10 ≦ X4 <90. , 0 <A2 ≦ 40, 10 <X4 + A2 ≦ 90.) The information recording medium according to claim 14 , comprising a material that can be expressed by: The oxide material layer has the following formula:
_{(D3) X4 (Cr 2 O} 3) A2 (h) Z3 (E2) 100-X4-A2-Z3 (mol%)
(Wherein D3 represents an oxide of at least one element selected from the group GM2, h represents at least one compound selected from the group consisting of Si ₃ N ₄ and SiC, and E2 is selected from the group GL2. X4 and A2 and Z3 can be represented by 10 ≦ X4 <90, 0 <A2 ≦ 40, 0 <Z3 ≦ 40, 10 <X4 + A2 + Z3 ≦ 90). The information recording medium according to claim 15 , comprising a material. The information recording medium according to any one of claims 12, 13, 17 and 18 , wherein the D3 is ZrO ₂ and the E2 is Ga ₂ O ₃ . At least one information recording medium according to any one of claim 1 to 19 including the recording layer. The information recording medium according to claim 20 , wherein the recording layer undergoes a phase transformation. The recording layer is made 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 21 , comprising any one material selected from Ag—In—Sb—Te and Sb—Te. The information recording medium according to claim 22 , wherein the recording layer has a thickness of 20 nm or less. 21. The information recording medium according to claim 20 , wherein the oxide material layer is disposed in contact with at least one surface of the recording layer. The information recording medium according to any one of claims 20 to 24 , wherein a plurality of recording layers including the recording layer are provided. A method for producing an information recording medium comprising an oxide-based material layer containing Zr, at least one element selected from the group GL1 consisting of La, Ga and In, and oxygen (O),
The oxide-based material layer, by using the Zr, at least one element selected from the group GL1, a sputtering target containing a oxygen (O), in viewing including the step of forming by sputtering,
The sputtering target has the following formula:
Zr _q1 L1 _t1 O _100-q1-t1 (atomic%)
(In the formula, L1 represents at least one element selected from the group GL1, and q1 and t1 satisfy 0 <q1 <34, 0 <t1 <50, and 20 <q1 + t1 <60). A method for manufacturing an information recording medium including a material. 27. The method for manufacturing an information recording medium according to claim 26 , wherein L1 is Ga. The sputtering target has the following formula:
(D1) _x1 (E1) _100-x1 (mol%)
(Wherein D1 represents an oxide of Zr, E1 represents an oxide of at least one element selected from the group GL1, and x1 satisfies 0 <x1 <100). The manufacturing method of the information recording medium of Claim 26 containing. Wherein D1 is ZrO _2, method of manufacturing an information recording medium according to claim 28 wherein E1 is Ga ₂ O _3. M1 (where M1 is a mixture of Zr and Hf or Hf), at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y, and oxygen (O) A method for producing an information recording medium comprising an oxide-based material layer comprising:
Forming the oxide-based material layer by a sputtering method using a sputtering target containing M1 and at least one element selected from the group GL2 and oxygen (O) ;
The sputtering target has the following formula:
M1 _q2 L2 _t2 O _100-q2-t2 (atomic%)
(Wherein, M1 represents a mixture of Zr and Hf or Hf, L2 represents at least one element selected from the group GL2, q2 and t2 are 0 <q2 <34, 0 <t2 <50, 20 <q2 + t2 <60 is satisfied.) A method for manufacturing an information recording medium including a material represented by : The method for manufacturing an information recording medium according to claim 30 , wherein L2 is Ga. The sputtering target has the following formula:
(D2) _x2 (E2) _100-x2 (mol%)
(Wherein D2 represents the oxide of M1, E2 represents an oxide of at least one element selected from the group GL2, and x2 satisfies 0 <x2 <100). A method for manufacturing an information recording medium according to claim 30 . Method of manufacturing an information recording medium according to claim 32 wherein E2 is Ga ₂ O _3. At least one element selected from the group GM2 consisting of Zr and Hf, at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y, Si, oxygen (O), A method for producing an information recording medium including an oxide-based material layer including:
Sputtering method using a sputtering target including the oxide material layer including at least one element selected from the group GM2, at least one element selected from the group GL2, Si, and oxygen (O). in viewing including the step of forming,
The sputtering target has the following formula:
M2 _q3 Si _r1 L2 _t3 O _100-q3-r1-t3 (atomic%)
(In the formula, M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and q3, r1, and t3 are 0 <q3 ≦ 32, 0 <r1. ≦ 32, 3 <t3 <43, 20 <q3 + r1 + t3 <60)) .   At least one element selected from the group GM2 consisting of Zr and Hf, at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y, Si, oxygen (O), A method for producing an information recording medium including an oxide-based material layer including:
  The oxide material layer is formed by sputtering using a sputtering target containing at least one element selected from the group GM2, at least one element selected from the group GL2, Si, and oxygen (O). Including the step of forming
  The sputtering target further includes at least one element selected from the group GK1 consisting of carbon (C), nitrogen (N) and Cr,
  The sputtering target has the following formula:
  M2 _q3 Si _r1 L2 _t3 K1 _j1 O _{100-q3-r1-t3-j1} (atom%)
(Wherein M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, K1 represents at least one element selected from the group GK1, q3 , R1, t3 and j1 satisfy the following condition: 0 <q3 ≦ 32, 0 <r1 ≦ 35, 2 <t3 ≦ 40, 0 <j1 ≦ 40, 20 <q3 + r1 + t3 + j1 <80. A method for manufacturing a medium. 36. The method of manufacturing an information recording medium according to claim 34 or 35 , wherein M2 is Zr and L2 is Ga. The sputtering target has the following formula:
(D3) _x3 (g) _z1 (E2) _100-x3-z1 (mol%)
Wherein D3 represents an oxide of at least one element selected from the group GM2, g represents at least one compound selected from the group consisting of SiO2, Si ₃ N ₄ and SiC, and E2 represents the group GL2 shows at least one oxide of element more selected, x3 and z1 is claim 34 comprising a material that can be represented by meeting the 10 ≦ x3 <90,0 <z1 ≦ 50,10 <x3 + z1 ≦ 90.) Or a method for producing an information recording medium according to 35 . The sputtering target has the following formula:
_{(D3) x3 (SiO 2)} z2 (f) a1 (E2) 100-x3-z2-a1 (mol%)
(Wherein D3 represents an oxide of at least one element selected from the group GM2, f represents at least one compound selected from the group consisting of SiC, Si ₃ N ₄ and Cr ₂ O ₃ , and E2 represents An oxide of at least one element selected from the group GL2, wherein x3, z2, and a1 satisfy 10 ≦ x3 <90, 0 <z2 ≦ 50, 0 <a1 ≦ 50, and 10 <x3 + z2 + a1 ≦ 90. 36. The method for producing an information recording medium according to claim 35 , comprising a material that can be represented by: At least one element selected from the group GM2 consisting of Zr and Hf, at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg and Y, Cr, oxygen (O), A method for producing an information recording medium including an oxide-based material layer including:
Sputtering method using a sputtering target including the oxide material layer including at least one element selected from the group GM2, at least one element selected from the group GL2, Cr, and oxygen (O). in viewing including the step of forming,
The sputtering target has the following formula:
M2 _q4 Cr _u L2 _t4 O _100-q4-u-t4 (atomic%)
(In the formula, M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and q4, u, and t4 are 0 <q4 ≦ 32, 0 <u. ≦ 25, 0 <t4 ≦ 40, and 20 <q4 + u + t4 <60)).   At least one element selected from the group GM2 consisting of Zr and Hf, at least one element selected from the group GL2 consisting of La, Ce, Al, Ga, In, Mg, and Y, Cr, oxygen (O), A method for producing an information recording medium including an oxide-based material layer including:
  Sputtering method using a sputtering target including the oxide material layer including at least one element selected from the group GM2, at least one element selected from the group GL2, Cr, and oxygen (O). Including the step of forming
  The sputtering target has the following formula:
  M2 _q4 Cr _u L2 _t4 Si _r2 K2 _j2 O _{100-q4-u-t4-r2-j2} (atom%)
(In the formula, M2 represents at least one element selected from the group GM2, L2 represents at least one element selected from the group GL2, and K2 represents a group GK2 composed of nitrogen (N) and carbon (C)). At least one element selected, q4, u, t4, r2 and j2 are 0 <q4 ≦ 32, 0 <u ≦ 25, 0 <t4 ≦ 40, 0 <r2 ≦ 30, 0 <j2 ≦ 40, 25 <q4 + u + t4 + r2 + j2 <85 is satisfied)). 41. The method of manufacturing an information recording medium according to claim 39 or 40 , wherein the M2 is Zr and the L2 is Ga. The sputtering target has the following formula:
(D3) _x4 (Cr ₂ O ₃ ) _a2 (E2) _100-x4-a2 (mol%)
(Wherein D3 represents an oxide of at least one element selected from the group GM2, E2 represents an oxide of at least one element selected from the group GL2, and x4 and a2 are 10 ≦ x4 <90. 40. The method of manufacturing an information recording medium according to claim 39 , comprising a material that can be expressed as: 0 <a2 ≦ 40, 10 <x4 + a2 ≦ 90 . The sputtering target has the following formula:
(D3) _x4 (Cr ₂ O ₃ ) _a2 (h) _z3 (E2) _100-x4-a2-z3 (mol%)
(Wherein D3 represents an oxide of at least one element selected from the group GM2, h represents at least one compound selected from the group consisting of Si ₃ N ₄ and SiC, and E2 is selected from the group GL2. X4, a2, and z3 can be expressed by 10 ≦ x4 <90, 0 <a2 ≦ 40, 0 <z3 ≦ 40, 10 <x4 + a2 + z3 ≦ 90). The method for producing an information recording medium according to claim 40 , comprising a material . Wherein D3 is ZrO _2, the method of manufacturing an information recording medium according to any one of claims 37,38,42 and 43 wherein the E2 is Ga ₂ O _3.

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