JP4227554B2 - Information recording medium and manufacturing method thereof - Google Patents

Description

  The present invention relates to an information recording medium that enables at least one of recording and reproduction of information by optical or electrical means, and a manufacturing method thereof.

  As a conventional information recording medium, the inventors have developed and commercialized 4.7 GB / DVD-RAM, which is a large-capacity rewritable phase change information recording medium that can be used as a data file and an image file (for example, , See Patent Document 1). The configuration of this information recording medium (DVD-RAM) is shown in FIG. The information recording medium shown in FIG. 6 has a first dielectric layer 102, a first interface layer 103, a recording layer 4, a second interface layer 105, and a second dielectric layer 106 on one surface of the substrate 1. The light absorption correction layer 7 and the reflection layer 8 have a multilayer film having a seven-layer structure in which the light absorption correction layer 7 and the reflection layer 8 are laminated in this order. In this information recording medium, the first dielectric layer 102 is disposed at a position closer to the laser beam incident side than the second dielectric layer 106. The first interface layer 103 and the second interface layer 105 have the same positional relationship. As described above, in the present specification, when the information recording medium includes two or more layers having the same function, the information recording medium is arranged in the order of “first”, “second” from the one closer to the incident laser beam. ”,“ Third ”,...

The first dielectric layer 102 and the second dielectric layer 106 increase the light absorption efficiency of the recording layer 4 by adjusting the optical distance, and reflectivity when the recording layer 4 is in a crystalline phase and non-recording layer 4 It has a function of increasing the signal amplitude by increasing the difference from the reflectance in the case of the crystalline phase. Conventionally, a mixture of 80 mol% ZnS and 20 mol% SiO ₂ used as a material for the dielectric layer (hereinafter referred to as (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) in this specification. The same applies to the mixture of), which is an amorphous material, has low thermal conductivity, is transparent, and has a high refractive index. In addition, (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) has a high film formation rate during film formation and good mechanical properties and moisture resistance. Thus, (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) is an excellent material for the dielectric layer of the information recording medium.

  If the thermal conductivity of the first dielectric layer 102 and the second dielectric layer 106 is low, the heat generated when the laser light enters the recording layer 4 diffuses in the in-plane direction of the dielectric layers 102 and 106. Hard to do. In particular, when the thermal conductivity of the second dielectric layer 106 is low, the heat is quickly diffused in the thickness direction from the recording layer 4 to the reflective layer 8, so that the recording layer 4 can be made in a shorter time. As a result, the amorphous mark (record mark) is easily formed. When it is difficult to form a recording mark, it is necessary to perform recording with a high peak power. However, when a recording mark is easily formed, recording can be performed with a low peak power. Thus, when the thermal conductivity of the dielectric layers 102 and 106 is low, recording can be performed with low peak power, so that the recording sensitivity of the information recording medium is increased.

  When the dielectric layers 102 and 106 have a high thermal conductivity, recording is performed with a high peak power, so that the recording sensitivity of the information recording medium is low. The dielectric layers 102 and 106 in the information recording medium exist in the form of a film that is so thin that the thermal conductivity cannot be accurately measured. For this reason, the inventors of the present application employ the recording sensitivity of the information recording medium as a relative criterion for knowing the magnitude of the thermal conductivity of the dielectric layer.

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

The first interface layer 103 and the second interface layer 105 prevent mass transfer that occurs between the first dielectric layer 102 and the recording layer 4 and between the second dielectric layer 106 and the recording layer 4. It has the function to do. (See Patent Document 2 and Patent Document 3 for a layer having a function of preventing mass transfer). The first and second interface layers 103 and 105 are included in the first and second dielectric layers 102 and 106 while the information is repeatedly rewritten by irradiating the recording layer 4 with laser light (ZnS) _80. This prevents (SiO ₂ ) ₂₀ (mol%) S atoms from diffusing into the recording layer 4. It is already known that when a large amount of S atoms diffuses into the recording layer 4, the reflectance of the recording layer 4 is lowered and the repeated rewriting performance deteriorates (see Non-Patent Document 1).

  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, and the mark shape at the time of rewriting is adjusted. It has a function of suppressing distortion. The reflection layer 8 has a function of optically increasing the amount of light absorbed by the recording layer 4, and thermally diffuses rapidly the heat generated in the recording layer 4 to rapidly cool the recording layer 4. It has a function of facilitating crystallisation. The reflective layer 8 also has a function of protecting the multilayer film from the use environment.

In this way, the information recording medium shown in FIG. 6 has a structure in which the seven layers functioning as described above are laminated, thereby providing excellent repeated rewriting performance and high reliability at a large capacity of 4.7 GB. Secured and commercialized.
JP 2001-322357 A JP-A-10-275360 (Claims) WO 97/34298 pamphlet (Claims) N. Yamada et al. Japanese Journal of Applied Physics Volume 37, 1998, p. 2104-2110

As described above, when (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) is used for the first and second dielectric layers, the first and second dielectric layers are brought into contact with the recording layer. When the recording layer is irradiated with a laser beam and information is repeatedly rewritten, S atoms of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) contained in the first and second dielectric layers are formed. Diffuses into the recording layer, causing a decrease in the reflectance of the recording layer, and the repeated rewriting performance deteriorates. Therefore, as in the information recording medium shown in FIG. 6, it is necessary to provide an interface layer for suppressing mass transfer between the recording layer and the dielectric layer in order to ensure repeated rewriting characteristics. However, considering the price of the medium, it is desirable that the number of layers constituting the medium is as small as one. This is because a reduction in the number of layers can realize a reduction in material costs, a reduction in the size of the manufacturing apparatus, and an increase in production volume due to a reduction in manufacturing time, resulting in a reduction in the price of the medium.

  The inventors of the present application examined the possibility of eliminating at least one of the first interface layer and the second interface layer as one method of reducing the number of layers. The interface layer is a very thin layer having a thickness of 2 nm to 5 nm and is structurally weak. For this reason, film breakage occurs during repeated recording of information, and as a result, atomic diffusion tends to occur. Therefore, it is desirable to eliminate the interface layer from the viewpoint of the stability of the information recording medium. However, in order to eliminate the interface layer, it is necessary to form the dielectric layer with a material that does not cause the mass transfer of S, that is, a material system that does not contain S atoms.

  As for the material of the dielectric layer, (1) sufficient light absorption into the recording layer is ensured to perform efficient recording, and sufficient reflected light is ensured to reproduce the recorded information satisfactorily. Therefore, it has a certain degree of transparency with respect to light of the wavelength to be recorded and reproduced, and (2) equal to or more than that of an information recording medium including a multilayer film having a seven-layer structure provided with an interface layer (3) Thermal stability and high melting point without melting even during repeated rewriting, (4) High film formation rate during film formation to ensure productivity (5) It is desired to be excellent in reliability.

  The present invention provides a material layer in which mass transfer to the recording layer is suppressed and adhesion to the recording layer is good even when formed so as to be in direct contact with the recording layer without providing an interface layer. Another object of the present invention is to provide an information recording medium having good repetitive rewriting performance.

A first information recording medium of the present invention is an information recording medium that includes a substrate and a recording layer, and enables at least one of recording and reproduction by irradiation of light or application of electric energy, Ga , Al, It is characterized by further including a material layer containing at least one element selected from the group GL consisting of Si and B, oxygen (O), and optionally containing nitrogen (N).

  A second information recording medium of the present invention is an information recording medium including a substrate and a recording layer, and capable of at least one of recording and reproduction by irradiation of light or application of electric energy, and includes Sn, Ga, and Zn. It further includes a material layer containing at least one element selected from the group GM consisting of, oxygen (O), at least one element selected from the group GA consisting of La or Ce, and fluorine (F). It is said.

A first information recording medium manufacturing method according to the present invention includes a substrate, a recording layer, and a material layer, and enables at least one of recording and reproduction by light irradiation or electrical energy application. The sputtering target includes the material layer including Ga , at least one element selected from the group GL consisting of Al, Si, and B, oxygen (O), and optionally nitrogen (N). And a step of forming by a sputtering method.

  A second information recording medium manufacturing method according to the present invention includes a substrate, a recording layer, and a material layer, and manufacturing an information recording medium capable of at least one of recording and reproduction by light irradiation or application of electrical energy. In the method, the material layer includes at least one element selected from the group GM consisting of Sn, Ga, and Zn, oxygen (O), and at least one element selected from the group GA consisting of La or Ce, The method includes a step of forming by a sputtering method using a sputtering target containing fluorine (F).

  According to the information recording medium and the manufacturing method thereof of the present invention, it is possible to provide an information recording medium having high recording sensitivity and high repetitive rewriting characteristics with a high productivity even if the number of constituent layers is reduced. Can do. In addition, since the material used for the material layer in the information recording medium of the present invention has low thermal conductivity and high adhesion to the recording layer, the recording layer is insulated in the information recording medium to which electric energy is applied. If it is used as a layer for this purpose, it is possible to cause a phase change of the recording layer with a smaller electric energy.

  In addition, since the material layer in the information recording medium of the present invention has excellent adhesion to other layers and has low heat conduction and high heat insulation properties, heat is generated not only in the recording medium using phase change but also in recording. It can also be used for other information recording media.

In the first information recording medium of the present invention, the material layer has at least one element selected from the group GM consisting of Sn, Ga and Zn and at least one element selected from the group GL consisting of Al, Si and B. And oxygen (O). The material layer may further contain nitrogen (N). By forming the material layer with such a material, it is possible to realize a film forming speed equal to or higher than (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) used for the dielectric layer of the conventional information recording medium. In addition, since the element constituting the material layer does not contain S, it is not necessary to provide a separate interface layer when the material layer is applied to the dielectric layer, and has a certain degree of transparency with respect to light having a wavelength for recording and reproduction. A dielectric layer can be formed. Furthermore, when such a material layer is used for the dielectric layer, sufficient recording sensitivity and rewriting performance can be ensured even if the dielectric layers are provided directly above and below the recording layer without using an interface layer. The first information recording medium of the present invention is a medium for recording and reproducing information by irradiating light or applying electrical energy. In general, light irradiation is performed by irradiating a laser beam, and electric energy is applied by applying a voltage to the recording layer. Hereinafter, the material of the material layer constituting the first information recording medium of the present invention will be described more specifically.

In the first information recording medium of the present invention, the material layer has the following composition formula:
M _H O _I L _J N _K (atomic%) (1)
(Wherein M represents at least one element selected from the group GM, L represents at least one element selected from the group GL, and H, I, J and K are 10 ≦ H ≦ 50, 10 ≦ I ≦ 70, 0 <J ≦ 40, 0 ≦ K ≦ 50 are satisfied.)
The material represented by these may be included. Here, “atomic%” is a compositional formula expressed by the composition formula (1) based on the total number of “M” atoms, oxygen atoms, “L” atoms, and nitrogen atoms (100%). It shows that there is. In the following composition formulas, “atomic%” is used for the same purpose. Further, the composition formula (1) represents only “M” atoms, oxygen atoms, “L” atoms, and nitrogen atoms included in the material layer. Therefore, a component other than these atoms may be included in the material layer including the material represented by the composition formula (1). Further, in the material represented by the composition formula (1), it does not matter what kind of compound each atom exists. The material is specified by such a composition formula when it is difficult to obtain the composition of the compound when examining the composition of the layer formed on the thin film. In reality, only the elemental composition (ie, the ratio of each atom) is obtained. This is because there are many cases of seeking. In the material represented by the composition formula (1), it is considered that most of the element M exists as an oxide together with oxygen atoms, and most of the element L exists as an oxide or nitride together with oxygen atoms or nitrogen atoms. .

  In the first information recording medium of the present invention, the element M contained in the material layer is preferably at least one of Sn and Ga. The material layer containing Sn is preferable from the viewpoint of productivity because it has a particularly high deposition rate among the material layers containing the elements constituting the group GM. In addition, a material layer containing Ga is more preferable because it has particularly excellent rewriting characteristics among material layers containing elements constituting the group GM.

When the first information recording medium of the present invention is an optical information recording medium, an element selected from the group GM, an element selected from the group GL, and oxygen (O) or oxygen (O) and nitrogen (N). One or both of the two dielectric layers adjacent to the recording layer using the material layer (hereinafter referred to as “oxide-based material layer” or “oxide-nitride-based material layer”) It is preferable to form a dielectric layer. For example, in the case of a recording medium based on phase change, the melting point of the main material system constituting the recording layer is about 500 to 700 ° C., whereas the elements constituting the group GM, that is, the oxides of Sn, Ga and Zn, have melting points. Is 1000 ° C. or higher and has excellent thermal stability. A dielectric layer containing a material having excellent thermal stability is not easily deteriorated and has excellent durability even when information is repeatedly rewritten on an information recording medium including the dielectric layer. Further, the elements constituting the group GL, that is, the nitrides and oxides of Al, Si, and B have good moisture resistance. Further, both the oxide and the nitride have good adhesion to the recording layer formed of the chalcogenide material. Therefore, in an information recording medium in which this oxide material layer or oxide-nitride material layer is formed as a dielectric layer,
(1) Since a dielectric layer not containing S can be formed in good contact with the recording layer, an interface layer is not necessary. (2) Repetition of the same level as or more than that of the conventional information recording medium shown in FIG. Durability to rewriting and moisture resistance can be imparted to the information recording medium. (3) Since the structure is complicated by mixing with a plurality of oxides or nitrides, the thermal conductivity of the dielectric layer is reduced. The recording layer is easily cooled rapidly, and the effect of increasing the recording sensitivity can be obtained.

  In the first information recording medium of the present invention, the material layer may include a material represented by the above composition formula (1) and containing Sn as M. Sn is an element that enables a higher deposition rate and high productivity among the elements constituting the group GM. Therefore, by applying the material layer containing Sn to either one or both of the two dielectric layers adjacent to the recording layer of the information recording medium, it has better repeated rewriting performance and excellent productivity. Information recording media can be manufactured at low cost.

  In the first information recording medium of the present invention, the material layer may include a material represented by the above composition formula (1) and containing Ga as M. Ga has an excellent effect of obtaining particularly good rewriting characteristics among the elements constituting the group GM. A highly reliable information recording medium that exhibits better repeated rewriting characteristics by applying a material layer containing Ga to one or both of two dielectric layers adjacent to the recording layer of the information recording medium Can be realized.

  In the first information recording medium of the present invention, the material layer is a material represented by the composition formula (1), and includes M as Sn and L as at least one element of Si and Al. It may contain material. As described above for Sn, Si has an excellent effect of improving the recording sensitivity among the elements constituting the group GL. In addition, since the film quality of the material layer becomes soft due to the inclusion of the Si oxide, film cracking and film breakage of the material layer due to repeated rewrite recording are suppressed. Better recording sensitivity by applying a material layer containing Sn and at least one of Si and Al to one or both of the two dielectric layers adjacent to the recording layer of the information recording medium It is possible to realize an information recording medium useful for higher density and higher speed recording technology.

  In the first information recording medium of the present invention, the material layer is a material represented by the above composition formula (1), and includes M as Ga and L as at least one element of Si and Al. It may contain material. Since Ga, Si, and Al are as described above, by applying the material layer containing this material to one or both of the two dielectric layers adjacent to the recording layer of the information recording medium, A highly reliable information recording medium having excellent recording sensitivity that exhibits excellent repeated rewriting characteristics can be realized.

  In the first information recording medium of the present invention, the material layer is a material represented by the above composition formula (1), which includes Sn and Ga as M, and at least one element of Si and Al as L The material containing may be included. By applying a material layer containing such a material to one or both of the two dielectric layers adjacent to the recording layer of the information recording medium, good recording sensitivity, excellent repeated rewriting performance, and high production And a highly reliable information recording medium can be manufactured at low cost.

In the second information recording medium of the present invention, the material layer is at least one element selected from the group GA consisting of at least one element selected from the group GM consisting of Sn, Ga and Zn, oxygen (O), and La or Ce. One element and fluorine (F) are included. The material layer included in the second information recording medium has, for example, the following composition formula:
M _H O _I A _D F _E (atomic%) (2)
(In the formula, M represents at least one element selected from the group GM, A represents at least one element selected from the group GA, and H, I, D, and E represent 10 ≦ H ≦ 50, 10 ≦ I ≦ 70, 0 <D ≦ 40, 0 <E ≦ 50 is satisfied.)
The material represented by these can be included. La and Ce are preferably used because they can be mixed with the group GM oxides to obtain good recording sensitivity and are also less expensive among rare earth metal fluorides. The material layer included in the second information recording medium is hereinafter referred to as an “oxide-fluoride material layer”.

  In the second information recording medium of the present invention, the element M contained in the material layer is preferably at least one of Sn and Ga. The material layer containing Sn is preferable from the viewpoint of productivity because it has a particularly high deposition rate among the material layers containing the elements constituting the group GM. In addition, a material layer containing Ga is more preferable because it has particularly excellent rewriting characteristics among material layers containing elements constituting the group GM.

  As described above, in the oxide-based material layer, the oxide-nitride-based material layer, and the oxide-fluoride-based material layer, at least one element selected from the group GM consisting of Sn, Ga, and Zn is oxygen And at least one element selected from the group GL consisting of Al, Si and B is present as an oxide or nitride together with oxygen or nitrogen and selected from the group GA consisting of La and Ce At least one element is considered to be present as a fluoride and can be identified as a layer containing these compounds. In the material layer thus specified, the oxide group of at least one element selected from the group GM includes an oxide group of an element selected from the group GM and an oxide group of an element selected from the group GL or When the amount combined with the nitride group is used as a reference (100 mol%), it is preferably contained in an amount of 50 mol% or more, more preferably 50 mol% to 95 mol%. The same applies to the case where the combined amount of the fluoride group of elements selected from the group GA is used as a reference.

  Here, the term “oxide group” is a general term for all oxides when the element selected from the group GM is 2 or more and two or more kinds of oxides are included in the layer. Used for. Alternatively, the term “oxide group” refers only to an oxide when there is only one element selected from the group GM and one oxide is included in the layer. The same applies to the terms “nitride group” and “fluoride group”. In other words, the oxide-based material layer, the oxide-nitride-based material layer, and the oxide-fluoride-based material layer are compounds other than those specified above (such compounds are also referred to as “third components”). .) May be included up to 10 mol%. This is because when the proportion of the third component exceeds 10 mol%, the thermal stability of the material layer is reduced, recording sensitivity and rewriting characteristics are deteriorated, and moisture resistance is liable to be reduced. It may be difficult to obtain.

  It should be noted that the dielectric layer formed of the material layer specified above may contain a few mol% or less of impurities or an element of the material composition constituting the adjacent layer.

  When the ratio of the oxide group of the element selected from the group GM is less than 50 mol%, the film formation rate and the moisture resistance tend to decrease. This is because the internal stress of the film of the material layer becomes too large, and local peeling from other layers is likely to occur depending on the film thickness to be formed.

  The oxide group of at least one element selected from the group GM may include an oxide of Sn or an oxide of Ga, and Si as an oxide group or nitride group of at least one element selected from the group GL. Nitride and Si oxide may be included, and the effects thereof are as described above.

In the first information recording medium of the present invention, the material layer has an oxide of at least one element selected from the group GM, preferably at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO. And at least one compound selected from AlN, Si ₃ N ₄ , Al ₂ O ₃ and SiO ₂ as at least one of an oxide and a nitride of at least one element selected from the group GL, Specifically, the following composition formula:
(D) _X (E) _100-X (mol%) (3)
Wherein D represents at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO, and E represents at least one selected from AlN, Si ₃ N ₄ , Al ₂ O ₃ and SiO ₂ . Represents a compound, and X satisfies 50 ≦ X ≦ 95.)
The material represented by these may be included. SnO ₂ , Ga ₂ O ₃ and ZnO all have a melting point as high as 1000 ° C. or higher, are thermally stable, and have a high deposition rate. AlN, Si ₃ N ₄ , Al ₂ O ₃ and SiO ₂ have good moisture resistance, and when mixed with the above-mentioned oxide group, the effect of reducing thermal conductivity is particularly high, resulting in the effect of improving recording sensitivity. Are better. It is also most suitable for practical use because of its low price. A preferred ratio of each compound is defined by X as described above. By applying such an oxide-nitride material layer to the dielectric layer in contact with the recording layer, the interface layer between the dielectric layer and the recording layer can be eliminated. Therefore, an information recording medium including such a material layer as a dielectric layer has good repetitive recording performance, moisture resistance, recording sensitivity, recording and rewritability.

In the first information recording medium of the present invention, the material layer has the following composition formula:
(SnO ₂ ) _A1 (Ga ₂ O ₃ ) _A2 (E1) _B (mol%) (4)
(In the formula, E1 represents at least one nitride of AlN and Si ₃ N ₄ , A1 and A2 may be 50 ≦ A1 + A2 ≦ 95, and one of A1 and A2 may be 0, and B is 5 ≦ B ≦ 50 is satisfied, and A1 + A2 + B = 100.)
It is more desirable if it contains the material represented by. The preferred ratio is defined by A1 and A2 as described above.

In the first information recording medium of the present invention, the material layer includes an oxide of at least one element selected from the group GM, and further includes SiO _2.
(D) _X (SiO ₂ ) _Y (E1) _100-XY (mol%) (5)
(In the formula, D represents at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO, E1 represents a nitride of at least one of AlN and Si ₃ N ₄ , and X and Y represent 50 ≦ X ≦ 95, 5 ≦ Y ≦ 35, and 55 ≦ X + Y ≦ 100.
The material represented by these may be included. The preferred ratio is defined by X and Y as described above. Here, the reason that X + Y ≦ 100 is shown because it includes the case where the nitride E1 is not included. The effect of SiO ₂ is as described above.

In the second information recording medium of the present invention, the material layer has the following composition formula:
(D) _X (A) _100-X (mol%) (6)
Wherein D represents at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO, A represents at least one selected from LaF ₃ and CeF ₃ , and X is 50 ≦ X ≦ 95 is satisfied.)
What contains the material represented by these is preferable. The ratio is defined by X as described above, and the oxide of at least one element selected from the group GM is the same as that of the oxide or oxide-nitride layer described above.

  The composition analysis of the oxide material layer, the oxide-nitride material layer, or the oxide-fluoride material layer included in the first and second information recording media of the present invention can be performed using, for example, an X-ray microanalyzer. Can be implemented. The analyzed composition is obtained as the atomic concentration of each element.

  The oxide-based material layer, the oxide-nitride-based material layer, or the oxide-fluoride-based material layer described above is formed on at least one surface of the recording layer in the first and second information recording media of the present invention. It is preferable to be provided so as to be in contact with each other, and it may be provided so as to be in contact with both surfaces of the recording layer. In the information recording medium of the present invention, the oxide material layer, the oxide-nitride material layer or the oxide-fluoride material layer exists as an interface layer located between the recording layer and the dielectric layer. May be.

  The first and second information recording media of the present invention are preferably those in which phase changes occur reversibly in their recording layers, that is, are preferably provided as rewritable information recording media. Specifically, the recording layer in which the phase change occurs reversibly includes Ge—Sb—Te, Ge—Sn—Sb—Te, Ge—Bi—Te, Ge—Sn—Bi—Te, and Ge—Sb—Bi—. It is preferable to include any one material selected from Te, Ge—Sn—Sb—Bi—Te, Ag—In—Sb—Te, and Sb—Te. These are all high-speed crystallization materials. Therefore, when a recording layer is formed from these materials, an information recording medium can be obtained that can be recorded at a high density and a high transfer rate, and that is excellent in reliability (specifically, record storability or rewrite storability).

  In the first and second information recording media of the present invention, in order for the recording layer to reversibly generate a phase change, it is desirable that the thickness of the recording layer is 15 nm or less. If the thickness exceeds 15 nm, the heat applied to the recording layer diffuses in-plane and becomes difficult to diffuse in the thickness direction, which may hinder information rewriting.

  More specifically, in the first and second information recording media of the present invention, the first dielectric layer, the recording layer, the second dielectric layer, and the reflective layer are formed in this order on one surface of the substrate. It may have the structure which was made. An information recording medium having this configuration is a medium that is recorded by light irradiation. In this specification, the “first dielectric layer” refers to a dielectric layer that is closer to the incident light, and the “second dielectric layer” refers to the incident light. It refers to a dielectric layer located farther away. That is, the irradiated light reaches the second dielectric layer from the first dielectric layer via the recording layer. The information recording medium having this configuration is used, for example, when recording / reproducing with a laser beam having a wavelength of about 660 nm. When the first and second information recording media of the present invention have this configuration, at least one of the first dielectric layer and the second dielectric layer is the above-described oxide-based material layer, An oxide-nitride material layer or an oxide-fluoride material layer is preferable. Further, both dielectric layers may be formed of any of the above-described material layers, and may be formed of material layers having different compositions as well as material layers having the same composition.

  As one form of the information recording medium having this configuration, a first dielectric layer, an interface layer, a recording layer, a second dielectric layer, a light absorption correction layer, and a reflective layer are formed in this order on one surface of the substrate. An information recording medium in which the second dielectric layer is formed of the oxide-based material layer, the oxide-nitride-based material layer, or the oxide-fluoride-based material layer and is in contact with the recording layer Is mentioned.

  Next, the manufacturing method of the 1st and 2nd information recording medium of this invention is demonstrated.

The manufacturing method of the 1st information recording medium of this invention includes the process of forming the material layer contained in the 1st information recording medium of this invention by sputtering method. According to the sputtering method, a material layer having substantially the same composition as that of the sputtering target can be formed. Therefore, according to this manufacturing method, an oxide material layer, an oxide-nitride material layer, or an oxide-fluoride material layer having a desired composition can be easily formed by appropriately selecting a sputtering target. . Specifically, as a sputtering target, the following composition formula:
M _h O _i L _j N _k (atomic%) (7)
(In the formula, M represents at least one element selected from the group GM, L represents at least one element selected from the group GL, and h, i, j and k are 10 ≦ h ≦ 50, 10 ≦ i ≦ 70, 0 <j ≦ 40, 0 ≦ k ≦ 50 are satisfied.)
The thing containing the material represented by can be used. In the composition formula (7), most of the elements M selected from the group GM are present in the form of oxides, most of the elements L selected from the group GL are present in the form of nitrides, and Si is in the form of oxides. It corresponds to the formula that represents the material that may be present in the elemental composition. According to this sputtering target, a dielectric layer containing a material represented by the composition formula (1) can be formed.

  The sputtering target including the material represented by the composition formula (7) may include Sn as M. According to such a sputtering target, a material layer containing Sn as M in the material represented by the composition formula (1) can be formed.

  The sputtering target including the material represented by the composition formula (7) may include Ga as M. According to such a sputtering target, a material layer containing Ga as M in the composition formula (1) can be formed.

  The sputtering target including the material represented by the composition formula (7) may include Sn as M and at least one of Si and Al as L. According to such a sputtering target, it is possible to form a material layer containing Sn as M in the composition formula (1) and at least one of Si and Al as L.

  The sputtering target containing the material represented by the composition formula (7) may contain Ga as M and at least one element of Si and Al as L. According to such a sputtering target, a material layer containing Ga as M in composition formula (1) and containing at least one element of Si and Al as L can be formed.

  The sputtering target including the material represented by the composition formula (7) may include Sn and Ga as M, and at least one element of Si and Al as L. According to such a sputtering target, a material layer containing Sn and Ga as M in the composition formula (1) and containing at least one element of Si and Al as L can be formed.

As a sputtering target used in the second method for producing an information recording medium of the present invention, the following composition formula:
M _h O _{i Ad Fe} (atomic%) (8)
(Wherein M represents at least one element selected from the group GM, A represents at least one element selected from the group GA, and h, i, d, and e are 10 ≦ h ≦ 50, 10 ≦ i ≦ 70, 0 <d ≦ 40, 0 <e ≦ 50 is satisfied.)
The thing containing the material represented by can also be used. According to this sputtering target, the material layer represented by the composition formula (2) can be formed.

  As a sputtering target used in the first method for producing an information recording medium of the present invention, an oxide of at least one element selected from the group GM consisting of Sn, Ga and Zn, and a group GL consisting of Al, Si and B are used. Those containing at least one of oxide and nitride of at least one element selected from the above can be used. The sputtering target used in the second method for producing an information recording medium of the present invention includes an oxide of at least one element selected from the group GM consisting of Sn, Ga and Zn, and a group GA consisting of La and Ce. What contains the fluoride of the at least 1 element chosen from more can be used. In this way, the sputtering target is specified because the sputtering target containing an element selected from group GM, oxygen, an element selected from group GL, an element selected from group GA, nitrogen, and fluorine is usually group GM. This is because the composition of the oxide of the element selected from the group, the oxide or nitride of the element selected from the group GL, and the fluoride of the element selected from the group GA are displayed and supplied. In addition, the inventors of the present application confirmed 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). Therefore, sputtering targets provided as oxides, oxides and nitrides, and mixtures of oxides and fluorides are also preferably used in the method for producing an information recording medium of the present invention.

  A sputtering target provided as an oxide or a mixture of oxide and nitride combines an oxide group of elements selected from group GM and a nitride group or oxide group of elements selected from group GL When the amount is based (100 mol%), the oxide group of the element selected from the group GM is preferably included in an amount of 50 mol% or more, and more preferably 50 mol% to 95 mol%. When a sputtering target in which the proportion of the oxide group is less than 50 mol% is used, the resulting oxide-based material layer or oxide-nitride-based material layer also has a proportion of the oxide group consisting of the group GM of less than 50 mol%. In some cases, it may be difficult to obtain an information recording medium that provides the desired effect. The same applies to the sputtering target provided as a mixture of oxide and fluoride.

  The sputtering target provided as a mixture of oxide, oxide and nitride, or oxide and fluoride is 50 mol in total of an oxide of Sn and an oxide of Ga as an oxide of an element selected from the group GM. If it contains more than%, productivity is high and more preferable. The sputtering target provided as an oxide or a mixture of oxide and nitride includes Si nitride as the nitride of an element selected from the group GL, and Si oxide as the oxide. If so, an information recording medium having more preferable characteristics can be produced.

More specifically, the sputtering target preferably used includes at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO as an oxide of an element selected from the group GM. It comprises at least one compound selected from AlN, Si ₃ N ₄ , Al ₂ O ₃ and SiO ₂ as at least one of oxide and nitride of the selected element. Such a sputtering target has the following composition formula:
(D) _x (E) _100-x (mol%) (9)
Wherein D represents at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO, and E represents at least one selected from AlN, Si ₃ N ₄ , Al ₂ O ₃ and SiO ₂ . Represents a compound, and x satisfies 50 ≦ x ≦ 95.)
It is preferable that the material represented by these is included. If this sputtering target is used, a material layer containing a material represented by the composition formula (3) can be formed.

The sputtering target including the material represented by the composition formula (9) may include SnO ₂ and Ga ₂ O ₃ as D. Such a sputtering target has the following composition formula:
(SnO ₂ ) _a1 (Ga ₂ O ₃ ) _a2 (E1) _b (mol%) (10)
(Wherein E1 represents a nitride of at least one of AlN and Si ₃ N ₄ , a1 and a2 may be 50 ≦ a1 + a2 ≦ 95, and either a1 or a2 may be 0, and b is 5 ≦ b ≦ 50 is satisfied, and a1 + a2 + b = 100.)
It is preferable that the material represented by these is included. By using this sputtering target, a material layer containing a material represented by the composition formula (4) can be formed.

The sputtering target including the material represented by the composition formula (9) includes a composition formula including SiO ₂ :
(D) _x (SiO ₂ ) _y (E1) _100-xy (mol%) (11)
(In the formula, D represents at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO, E1 represents a nitride of at least one of AlN and Si ₃ N ₄ , and x and y represent 50 ≦ x ≦ 95, 5 ≦ y ≦ 35, and 55 ≦ x + y ≦ 100.
It may contain the material represented by these. If this sputtering target is used, a material layer containing a material represented by the composition formula (5) can be formed.

Alternatively, a sputtering target including an oxide of an element selected from the group GM and a fluoride of an element selected from the group GA may be used. Such a sputtering target has the following composition formula:
(D) _x (A) _100-x (mol%) (12)
Wherein D represents at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO, A represents at least one selected from LaF ₃ and CeF ₃ , and x is 50 ≦ x ≦ 95 is satisfied.)
It may contain the material represented by these. By using this sputtering target, a material layer containing a material represented by the composition formula (6) can be formed.

  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 information recording medium for recording and reproducing information using laser light will be described. FIG. 1 shows a partial cross section of the information recording medium.

  As shown in FIG. 1, the information recording medium of the present embodiment has a first dielectric layer 2, a recording layer 4, a second dielectric layer 6, and a light absorption correction layer 7 on one surface of a substrate 1. And the reflective layer 8 are laminated in this order, and the bonded substrate 10 is further bonded to the reflective layer 8 with the adhesive layer 9. The information recording medium having this configuration can be used as a 4.7 GB / DVD-RAM for recording / reproducing with a red laser beam having a wavelength of around 660 nm. Laser light is incident on the information recording medium having this configuration from the substrate 1 side, and information is recorded and reproduced by the incident laser light. The information recording medium according to the present embodiment does not have an interface layer between the recording layer 4 and the first and second dielectric layers 2 and 6, respectively. It differs from the medium.

  The substrate 1 is usually a transparent disk-shaped plate. In the substrate 1, a guide groove for guiding laser light may be formed on the surface on the side where the first dielectric layer 2 and the recording layer 4 are formed, as shown in FIG. 1. When the guide groove is formed in the substrate 1, when the cross section of the substrate 1 is viewed, a groove portion and a land portion are formed. It can be said that the groove portion is located between two adjacent land portions. Therefore, the surface of the substrate 1 on which the guide groove is formed has a top surface and a bottom surface connected by the side walls. In the present specification, a surface on the side closer to the laser beam incident side is referred to as a “groove surface” for the sake of convenience, and a surface on the far side is referred to as a “land surface” for the sake of convenience. In FIG. 1, the bottom surface 20 of the guide groove of the substrate 1 corresponds to a groove surface, and the top surface 21 corresponds to a land surface. The same applies to the information recording medium shown in FIG.

  The step between the groove surface 20 and the land surface 21 of the substrate 1 is preferably 40 nm to 60 nm. In the substrate 1 constituting the information recording medium shown in FIG. 2 described later, the step between the groove surface 20 and the land surface 21 is preferably within this range. Further, it is desirable that the surface of the substrate 1 on the side where no other layer is formed is smooth. Examples of the material of the substrate 1 include a resin such as polycarbonate, amorphous polyolefin, or polymethyl methacrylate (PMMA), or a material having optical transparency such as glass. In view of moldability, price and mechanical strength, polycarbonate is preferably used. In the information recording medium of the present embodiment, the thickness of the substrate 1 is about 0.5 to 0.7 mm.

The recording layer 4 in the present embodiment is a layer in which a recording mark is formed by causing a phase change between a crystalline phase and an amorphous phase by light irradiation or application of electrical energy. If the phase change is reversible, it can be erased or rewritten. As the reversible phase change 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, a GeTe—Sb ₂ Te ₃ pseudobinary composition is preferable, and in that case, 4Sb ₂ Te ₃ ≦ GeTe ≦ 50 Sb ₂ Te ₃ is preferable. In the case of GeTe <4Sb ₂ Te ₃ , the change in the amount of reflected light before and after recording is small and the quality of the readout signal is lowered, and in the case of 50Sb ₂ Te ₃ <GeTe, the volume change between the crystalline phase and the amorphous phase is large and repeated. This is because the rewriting performance is degraded. 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. This is because if the Sn content 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 part of Sb of Ge—Sb—Te or Ge—Sn—Sb—Te with Bi.

Ge—Bi—Te is a mixture of GeTe and Bi ₂ Te ₃ . In this mixture, it is preferable that 8Bi ₂ Te ₃ ≦ GeTe ≦ 25 Bi ₂ Te ₃ . In the case of GeTe <8Bi ₂ Te ₃ , the crystallization temperature is lowered and the recording storability is likely to be deteriorated. In the case of 25Bi ₂ Te ₃ <GeTe, the volume change between the crystalline phase and the amorphous phase is large, and repeated rewriting performance. This is because of a decrease.

  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 4 than the Bi substitution. In the recording layer 4, the Sn content is preferably 10 atomic% or less. This is because 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, it is preferable that _{4 (Sb-Bi) 2 Te} 3 ≦ (Ge-Sn) Te ≦ 25 (Sb-Bi) 2 Te 3. (Ge-Sn) Te <4 (Sb-Bi) For ₂ Te _3, the variation in the amount of reflected light before and after recording is small, the read signal quality is degraded. In the case of 25 (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 4, the Bi content is preferably 10 atomic% or less, and the Sn content is preferably 20 atomic% or less. This is because if the contents of Bi and Sn are within these ranges, good recording mark storage stability can be obtained.

  Examples of other materials that reversibly undergo phase change include Ag—In—Sb—Te, Ag—In—Sb—Te—Ge, and Sb—Te containing 70 atomic% or more of Sb.

As the irreversible phase change material, for example, TeO _x + α (α is Pd, Ge, etc.) is preferably used (see Japanese Patent Publication No. 7-25209 (Patent No. 2006849)). The information recording medium in which the recording layer 4 is an irreversible phase change material is 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 configuration of the information recording medium of 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 changes phase, the thickness of the recording layer 4 is preferably 15 nm or less, and more preferably 12 nm or less, as described above. The lower limit of the thickness of the recording layer 4 is not particularly limited, but is preferably 3 nm or more.

  The first dielectric layer 2 and the second dielectric layer 6 in the present embodiment are composed of an oxide of at least one element selected from the group GM composed of Sn, Ga and Zn, and Al, Si and B. It is an oxide-based material layer or an oxide-nitride-based material layer formed of a material containing at least one of an oxide and a nitride of at least one element selected from the group GL. The first dielectric layer 2 and the second dielectric layer 6 are selected from an oxide of at least one element selected from the group GM consisting of Sn, Ga and Zn, and a group GA consisting of La and Ce. It may be an oxide-fluoride material layer formed of a material containing at least one element fluoride.

In general, the material of the dielectric layer constituting the information recording medium is (1) transparent, and (2) equivalent to or more than the configuration in which an interface layer is provided between the dielectric layer and the recording layer. Recording sensitivity, (3) high melting point, no melting during recording, (4) high deposition rate, and (5) adhesion with the recording layer 4 formed of a chalcogenide material. It is required to have good properties. The transparency is a characteristic necessary for allowing the laser beam incident from the substrate 1 side to pass and reach the recording layer 4. This characteristic is particularly required for the first dielectric layer 2 on the incident side. The materials of the first and second dielectric layers 2 and 6 are such that the obtained information recording medium is a conventional dielectric layer made of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) and a recording layer. It is necessary to select the recording medium so as to have a recording sensitivity equal to or higher than that of the information recording medium in which the interface layer is located between. Further, the high melting point is a characteristic necessary for ensuring that the materials of the first and second dielectric layers 2 and 6 do not enter the recording layer 4 when the laser beam of the peak power level is irradiated. And required for both the first and second dielectric layers 2 and 6. When the materials of the first and second dielectric layers 2 and 6 are mixed into the recording layer 4, the repeated rewrite performance is significantly lowered. In order to obtain good productivity, a high deposition rate is also required. Further, good adhesion to the recording layer 4 which is a chalcogenide material is a characteristic necessary for ensuring the reliability of the information recording medium, and the first and second dielectric layers 2 and 6 Both are required.

Of the components contained in the oxide-based material layer, oxide-nitride-based material layer, and oxide-fluoride-based material layer, the oxides of the elements constituting the group GM are all transparent and have a melting point. , High thermal stability, and good adhesion to the recording layer. Therefore, these oxides can ensure good repeated rewriting performance of the information recording medium. The oxides of Si and Al, which are elements constituting the group GL, are excellent in moisture resistance, and by mixing with the oxides of elements constituting the group GM, the thermal conductivity is reduced to improve the recording sensitivity. Since the film quality is softened, it is possible to suppress film cracking and film breakage due to repeated rewrite recording. Therefore, according to the oxides of Si and Al, it is possible to ensure the recording sensitivity and reliability of the information recording medium. Examples of the oxide of the elements constituting the group GM include SnO ₂ , Ga ₂ O _3, and ZnO. Examples of Si and Al oxides include SiO ₂ and Al ₂ O ₃ .

  By using a material that does not contain S and is made of a mixture of the above oxides, the first dielectric layer 2 and the second dielectric layer 6 are formed so as to be in contact with the recording layer 4, thereby repeatedly rewriting performance. In addition, an information recording medium which is excellent in adhesion and has good adhesion between the recording layer 4 and the first and second dielectric layers 2 and 6 can be realized. In addition, by mixing Si and Al oxides with the oxides of the elements constituting the group GM, the layer structure is complicated, so that the heat conduction in the first and second dielectric layers 2 and 6 is suppressed. . Therefore, if the oxide-based material layer is used for the first and second dielectric layers 2 and 6, the effect of quenching the recording layer 4 can be enhanced, so that the recording sensitivity of the information recording medium can be increased.

Of the components contained in the oxide-nitride material layer, the nitrides of elements constituting the group GL include, for example, AlN, Si ₃ N ₄ , BN, and the like. All of these nitrides have a high melting point, good moisture resistance, and by mixing with the oxides of the elements that constitute the group GM, the oxide structure is complicated to reduce heat conduction and improve recording sensitivity. Can be made.

As a specific example of such an oxide-nitride material layer, for example, in the material represented by the composition formula (3), that is, (D) _X (E) _100-X (mol%), E The thing containing the material at the time of using nitride is mentioned. In this formula, D is at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO. E is a nitride and is at least one selected from Si ₃ N ₄ and AlN. X indicating the mixing ratio of each compound satisfies 50 ≦ X ≦ 95. If the mixing ratio of D is less than 50 mol%, the adhesion with the recording layer becomes insufficient, the rewriting characteristics are liable to deteriorate, the film forming speed is slowed, and the productivity is hardly increased. When the mixing ratio of D is greater than 95 mol%, the mixing effect of Si ₃ N ₄ and AlN is difficult to be exhibited, and it is particularly insufficient for improving and improving the recording sensitivity.

Another more preferable specific example of the oxide-nitride material layer is represented by the composition formula (4), that is, (SnO ₂ ) _A1 (Ga ₂ O ₃ ) _A2 (E1) _B (mol%). It contains the material. E1 is at least one nitride selected from Si ₃ N ₄ and AlN. Here, A1 and A2 are 50 ≦ A1 + A2 ≦ 95, and either one of A1 and A2 may be 0, as long as at least one of SnO ₂ and Ga ₂ O ₃ is included. B satisfies 5 ≦ B ≦ 50. The reason for setting such a numerical range of A1 + A2 is the same as in the composition formula (3). Further, when Si ₃ N ₄ and AlN exceed the upper limit (50 mol%), the adhesion to the recording layer 4 is lowered, and when it is less than 5 mol%, the recording sensitivity becomes insufficient.

Further, a composition formula (5) containing an oxide of Si, that is, an oxide or oxide-nitride material represented by (D) _X (SiO ₂ ) _Y (E1) _100-XY (mol%) A dielectric layer may be formed. Here, D represents at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO, and E1 represents at least one nitride selected from Si ₃ N ₄ and AlN. X and Y indicating the mixing ratio satisfy 50 ≦ X ≦ 95, 5 ≦ Y ≦ 35, and 55 ≦ X + Y ≦ 100. The reason why X is in such a numerical range is the same as in the case of the composition formula (3). The reason why Y is set in such a range is that if Y is less than 5, the effect of softening the film and suppressing film peeling due to rewriting is insufficient, and if Y exceeds the upper limit of 35, recording is performed. This is because it is difficult to obtain the effect of improving the sensitivity, and the productivity is not increased because the film forming speed is lowered.

About the specific example of said oxide-fluoride type material, it is a material represented by composition formula (6), ie, (D) _X (A) _100-X (mol%). Here, D represents at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO, A represents at least one fluoride selected from LaF ₃ and CeF ₃ , and represents a mixing ratio X Is 50 ≦ X ≦ 95. The reason for making the numerical range of X in this way is the same as in the case of the composition formulas (3) to (5).

  Even if the dielectric layer is formed in contact with the recording layer by forming the dielectric layer with the oxide material, oxide-nitride material or oxide-fluoride material as described above, it is good. Recording sensitivity, rewriting characteristics and reliability can be ensured.

  The oxide material, oxide-nitride material, and oxide-fluoride material may contain a third component other than the compounds shown above, and in particular contain impurities of several percent or less. It does not matter. Further, even if the compositional elements of the layers formed in the vicinity are mixed somewhat, the thermal stability and moisture resistance do not change and are preferably used as the first dielectric layer 2 and the second dielectric layer 6. The third component is inevitably included when the dielectric layer is formed of an oxide material, oxide-nitride material, or oxide-fluoride material, or is inevitably formed It is. Examples of the third component include at least one of a dielectric, metal, metalloid, semiconductor, and nonmetal.

Dielectric materials included as the third component include, for example, Al ₂ O ₃ , Bi ₂ O ₃ , CeO ₂ , CoO, 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 , In ₂ O ₃ , La ₂ O ₃ , MnO, MgSiO ₃ , Nb ₂ O ₅ , Nd ₂ O ₃ , NiO, Sc ₂ O ₃ , Sm ₂ O ₃ , SnO, Ta ₂ O ₅ , Tb ₄ O ₇ , TeO ₂ , TiO ₂ , VO, WO ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , ZrO ₂ , ZrSiO ₄ , CrB ₂ , LaB ₆ , ZrB ₂ , CrN, Cr ₂ N HfN, NbN, 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.

  The metal contained as the third component is, for example, 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.

  The semimetal and semiconductor contained as the third component are, for example, C, Ge, and the like, and nonmetals are, for example, Sb, Bi, Te, Se, and the like.

The first dielectric layer 2 and the second dielectric layer 6 are formed of oxide material layers, oxide-nitride material layers, or oxide-fluoride material layers having different compositions. May be. The first dielectric layer 2 is preferably formed of a material having a higher moisture resistance. For example, the first dielectric layer 2 has a composition formula (5), that is, (D) _X (SiO ₂ ) _Y ( E1) In the material represented by _100-XY (mol%), D is SnO ₂ and Ga ₂ O ₃ and is an example in which E1 is not included (SnO ₂ ) ₄₀ (Ga ₂ O ₃ ) ₄₀ It is preferably formed of (SiO ₂ ) ₂₀ (mol%). The second dielectric layer 6 is preferably formed of a material having a composition so as to increase the quenching effect of the recording layer. For example, the composition formula (4), that is, (SnO ₂ ) _A1 (Ga ₂ O ₃ ) In the material represented by _A2 (E1) _B (mol%), (SnO ₂ ) ₃₅ (Ga ₂ O ₃ ) ₄₀ (Si ₃ N ₄ ) ₂₅ (E1 is an example in the case where E1 is Si ₃ N ₄ mol%).

The first dielectric layer 2 and the second dielectric layer 6 may be formed of the same material, or may be formed of different materials. For example, the first dielectric layer 2 is formed of a mixed material of ZnO—Si ₃ N ₄ —SiO ₂ , and the second dielectric layer 6 is formed of a mixed material of SnO ₂ —Ga ₂ O ₃ —LaF _3. It is also possible to form. As described above, the oxide-based material, the oxide-nitride-based material, and the oxide-fluoride-based material used for the first dielectric layer 2 and the second dielectric layer 6 depend on a desired function. Further, it can be formed by optimizing the kinds of oxides, nitrides and fluorides, and their mixing ratio.

  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 light reflectance Rc (when recording layer 4 is in a crystalline phase) %) And the light reflectance Ra (%) of the information recording medium when the recording layer 4 is in the amorphous phase, and the light of 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 Can be adjusted. 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, the matrix method (for example, see “Wave Optics” by Hiroshi Kubota, Iwanami Shinsho, 1971, Chapter 3).

The dielectric layers using the oxide-based material layer, the oxide-nitride-based material layer, and the oxide-fluoride-based material layer described above have different refractive indexes depending on their compositions. When the refractive index of the dielectric layer is n, the film thickness is d (nm), and the wavelength of the laser light is λ (nm), the optical path length nd is expressed by nd = aλ. Here, a is a positive number. In order to improve the signal quality by increasing the reproduction signal amplitude of the recording mark of the information recording medium, for example, it is preferable that 15% ≦ Rc and Ra ≦ 2%. In order to eliminate or reduce mark distortion due to rewriting, it is preferable that 1.1 ≦ Ac / Aa. The optical path lengths (aλ) of the first dielectric layer 2 and the second dielectric layer 6 were 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, it is represented by the composition formula (4), that is, (SnO ₂ ) _A1 (Ga ₂ O ₃ ) _A2 (E1) _B (mol%), and the refractive index n is 1.8 to 2.3. When the first dielectric layer 2 is formed of a material, it has been found that the thickness is preferably 110 nm to 160 nm. Moreover, when forming the 2nd dielectric material layer 6 with this material, it turned out that the thickness becomes like this. Preferably it is 35-60 nm.

  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 refractive index n is 3 or more and 5 or less, and the extinction coefficient k is 1 or more and 4 or less. It can be formed using a material. Specifically, amorphous Ge alloys such as Ge—Cr and Ge—Mo, amorphous Si alloys such as Si—Cr, Si—Mo, and Si—W, Te compounds, and Ti, Zr, Nb It is preferable to use a material selected from crystalline metals, metalloids and semiconductor materials such as 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 also has a function of protecting the multilayer film including 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 adjusting the thermal conductivity or optical properties (for example, 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. All of 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 100 nm.

  The adhesive layer 9 may be formed using a material having high heat resistance and high adhesiveness, such as an ultraviolet curable resin. Specifically, a photo-curing material whose main component is an acrylate resin or a methacrylate resin, a material whose main component is an epoxy resin, a hot melt material, or the like can be used. Further, if necessary, a protective coat 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 forming the adhesive layer 9. The thickness of the adhesive layer 9 is preferably 15 to 40 μm, more preferably 20 to 35 μm.

  The bonded substrate 10 has a function of enhancing the mechanical strength of the information recording medium and protecting the laminated body from the first dielectric layer 2 to the reflective layer 8. The preferred material for the bonded substrate 10 is the same as the preferred material for the substrate 1.

  The information recording medium of the present embodiment is a single-sided structure disc having one recording layer, but is not limited to this and may have two or more recording layers.

  Next, a method for manufacturing the information recording medium of the present embodiment will be described.

  In the information recording medium of the present embodiment, the substrate 1 (for example, having a thickness of 0.6 mm) on which the guide grooves (the groove surface 20 and the land surface 21) are formed is disposed in the film forming apparatus. A step of forming the first dielectric layer 2 on the formed surface (step a), a step of forming the recording layer 4 (step b), and a step of forming the second dielectric layer 6 (step c). ), A step of forming the light absorption correction layer 7 (step d) and a step of forming the reflective layer 8 (step e), and a step of forming the adhesive layer 9 on the surface of the reflective layer 8; And it manufactures by implementing the process of bonding the bonding substrate 10 together. In this specification, the term “surface” for each layer refers to the surface exposed when each layer is formed (a surface perpendicular to the thickness direction) unless otherwise specified.

  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 a sputtering method. Here, first, an example of a sputtering apparatus used in this embodiment will be described. FIG. 5 shows a state where a film is formed using a sputtering apparatus. As shown in FIG. 5, 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. The substrate 35 (here, the substrate is a base material for volume of the film) 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. The gas introduced by sputtering may be performed in a mixed gas atmosphere such as oxygen gas or nitrogen gas in addition to Ar gas, depending on the material layer to be formed.

  As the sputtering target used in step a, an oxide of at least one element selected from the group GM consisting of Sn, Ga and Zn and an oxidation of at least one element selected from the group GL consisting of Al, Si and B A sputtering target comprising at least one of an oxide and a nitride, an oxide of at least one element selected from the group GM, and a fluoride of at least one element selected from the group GA consisting of La and Ce A sputtering target containing is used. As such a sputtering target, preferably, a material represented by the composition formulas (7) and (8) is used as a result of elemental analysis. According to such a sputtering target, a dielectric is formed by an oxide-based material layer, an oxide-nitride-based material layer, or an oxide-fluoride-based material layer containing a material represented by the composition formulas (1) and (2). Layers 2 and 6 can be formed.

  As described above, one or more elements selected from the group GM, one or more elements selected from the group GL, one or more elements selected from the group GA, and oxygen (O) are further included. Accordingly, the sputtering target containing nitrogen (N) or fluorine (F) includes an oxide of an element of group GM and an oxide or nitride of an element of group GL or a fluoride of an element of group GA. Provided in the form of a mixture. The sputtering target used in the manufacturing method in the present embodiment preferably contains 50 mol% or more, more preferably 50 to 95 mol%, of an oxide group of an element selected from group GM.

The sputtering target containing the specific oxide and nitride is selected from at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO, and AlN, Si ₃ N ₄ , Al ₂ O ₃ and SiO _2. A material comprising at least one compound can be used. More specifically, composition formula (9), that is, (D) _x (E) _100-x (mol%) (wherein D is at least one selected from SnO ₂ , Ga ₂ O ₃ and ZnO). E represents one oxide, E represents at least one compound selected from AlN, Si ₃ N ₄ , Al ₂ O ₃ and SiO ₂ , and x satisfies 50 ≦ x ≦ 95. Targets containing can be used. According to this target, a layer containing a material represented by the composition formula (3) can be formed.

Further, a sputtering target containing SnO ₂ and Ga ₂ O ₃ may be used. More specifically, the composition formula (10), that is, (SnO ₂ ) _a1 (Ga ₂ O ₃ ) _a2 (E1) _b (mol%) (in the composition formula, E1 is selected from AlN and Si ₃ N _4. At least one nitride, a1 and a2 are 50 ≦ a1 + a2 ≦ 95, and either a1 or a2 may be 0, and b satisfies 5 ≦ b ≦ 50. It is preferable that it is included. If this sputtering target is used, the layer containing the material represented by the composition formula (4) can be formed.

Further, a sputtering target containing SiO ₂ may be used, and the composition formula (11), that is, (D) _x (SiO ₂ ) _y (E1) _100-xy (mol%) (in the composition formula, D is At least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO, E1 at least one nitride selected from AlN and Si ₃ N ₄ , and x and y are 50 ≦ x ≦ 95, 5 ≦ y ≦ 35, 55 ≦ x + y ≦ 100.) May be included. If this sputtering target is used, the layer containing the material represented by the composition formula (5) can be formed.

Alternatively, a sputtering target containing an oxide of an element selected from the group GM and a fluoride of an element selected from the group GA may be used. More specifically, the composition formula (12), that is,
(D) _x (A) _100-x (mol%) (in the composition formula, D represents at least one oxide selected from SnO ₂ , Ga ₂ O ₃ and ZnO, and A represents LaF ₃ and CeF _3. At least one selected, and x may include a material represented by 50 ≦ x ≦ 95. If this sputtering target is used, the layer containing the material represented by the composition formula (6) can be formed.

  The layer containing the above material may contain a third component other than these compounds, and may contain impurities of several percent or less. Moreover, the composition elements of the layers formed in the vicinity may be mixed somewhat. The components that can be included as the third component are as exemplified above.

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. Similar to step a, another gas may be introduced depending on the purpose. 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 may be formed by using a sputtering target containing the same compound as the first dielectric layer 2 but having a different mixing ratio, or a sputtering target containing a different compound. For example, the first dielectric layer 2 is formed of a mixed material of ZnO—Si ₃ N ₄ —SiO ₂ , and the second dielectric layer 6 is a mixed system of SnO ₂ —Ga ₂ O ₃ —LaF ₃ . It can also be made of a material. As described above, the first dielectric layer 2 and the second dielectric layer 6 have the optimum types of oxides, nitrides and fluorides, and / or their mixing ratios, depending on the desired function. Can be formed.

  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 and Ge—Mo, amorphous Si alloys such as Si—Cr, Si—Mo and Si—W, Te compounds, and Ti, Zr, Nb, Ta, A material made of a material selected from a crystalline metal such as Cr, Mo, W, SnTe, and PbTe, a semimetal, and a semiconductor material is used. Sputtering is generally 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, an alloy material such as Al—Cr, Al—Ti, Ag—Pd, Ag—Pd—Cu, Ag—Pd—Ti, or Au—Cr can be used.

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

  After the reflective layer 8 is formed, the substrate 1 on which the first dielectric layer 2 to the reflective layer 8 are sequentially laminated 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 coating method. The bonded substrate 10 is brought into close contact with the applied ultraviolet curable resin, and ultraviolet rays are irradiated from the bonded 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 of Embodiment 1 can be manufactured by sequentially performing the steps a to e, the formation step of the adhesive layer, and the bonding step of the bonded substrate 10.

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

  The information recording medium of the present embodiment shown in FIG. 2 has a first dielectric layer 102, an interface layer 103, a recording layer 4, a second dielectric layer 6, and a light absorption correction layer on one surface of a substrate 1. 7 and the reflective layer 8 are formed in this order, and the bonded substrate 10 is bonded to the reflective layer 8 with the adhesive layer 9. The information recording medium of the present embodiment is different from the conventional information recording medium shown in FIG. 6 in that no interface layer is provided between the recording layer 4 and the second dielectric layer 6. 1 is different from the information recording medium shown in FIG. 1 in that the first dielectric layer 102 and the interface layer 103 are laminated in this order between the substrate 1 and the recording layer 4. In the present embodiment, the second dielectric layer 6 is the same as the first and second dielectric layers in the information recording medium of the first embodiment. It is a material layer or an oxide-fluoride material layer. 2, the same reference numerals as those used in FIG. 1 represent components having the same functions, and are formed by the materials and methods described with reference to FIG. 1. Therefore, the detailed description of the components already described in FIG. 1 is omitted here.

In the information recording medium of the present embodiment, the first dielectric layer 102 is made of the material ((ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol) used for the dielectric layer that constitutes the conventional information recording medium. %)). Therefore, the interface layer 103 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. A preferable material and thickness of the interface layer 103 are, for example, a mixed material such as ZrO ₂ —SiO ₂ —Cr ₂ O ₃ or Ge—Cr, and the thickness is preferably 1 to 10 nm, and 2 to 7 nm. Is more preferable. If the interface layer 103 is too thick, the optical reflectivity and absorptance of the laminate from the first dielectric layer 102 to the reflective layer 8 formed on the surface of the substrate 1 change, which affects the recording / erasing performance. Because it affects.

  Next, a method for manufacturing the information recording medium of the present embodiment will be described. In the present embodiment, a step of forming the first dielectric layer 102 on the surface of the substrate 1 on which the guide groove is formed (step h), a step of forming the first interface layer 103 (step i), The step of forming the recording layer 4 (step b), the step of forming the second dielectric layer 6 (step c), the step of forming the light absorption correction layer 7 (step d), and the reflective layer 8 are formed. The information recording medium 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 bonded substrate 10 together. Since steps b, c, d, and e are as described in the first embodiment, detailed description thereof is omitted here. After the process of bonding the bonded substrate 10 is completed, an initialization process is performed as necessary to obtain an information recording medium as described in relation to the first embodiment.

  As described above, in the first and second embodiments, the information recording medium for recording / reproducing with the laser beam has been described as the embodiment of the information recording medium of the present invention with reference to FIG. 1 and FIG. The recording medium is not limited to these forms. The information recording medium of the present invention is arbitrary as long as the above-described oxide-based material layer, oxide-nitride-based material layer, or oxide-fluoride-based material layer is used for the dielectric layer in contact with the recording layer. It can take the form of That is, the present invention can be 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 information recording medium of the present invention is suitable for recording at various wavelengths. Therefore, the configuration and manufacturing method of the information recording medium of the present invention can be applied to, for example, a DVD-RAM or DVD-RW that records and reproduces with a laser beam having a wavelength of 630 to 680 nm, or a large capacity that records and reproduces with a laser beam having a wavelength of 400 to 450 nm. Applicable to optical discs and the like.

(Embodiment 3)
As an embodiment 3 of the present invention, an example of an information recording medium for recording and reproducing information by applying electric energy will be described. FIG. 3 is a perspective view of the information recording medium of the present embodiment.

  As shown in FIG. 3, the information recording medium of the present embodiment is a memory 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 memory recording unit 203 has a configuration including a cylindrical recording layer 205 and a dielectric layer 206 surrounding the recording layer 205. Unlike the information recording medium described in Embodiments 1 and 2 with reference to FIGS. 1 and 2, in the memory of this embodiment, the recording layer 205 and the dielectric layer 206 are formed on the same plane, and Not in a stacked 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 electrode 202, and the upper electrode 204 in the memory, they can be called “layers”. is there. 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, for example, a semiconductor substrate such as an Si substrate, a substrate made of polycarbonate resin or acrylic resin, an insulating substrate such as an SiO ₂ substrate and an Al ₂ O ₃ substrate, or the like can be used. 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, for example, by sputtering a metal such as Au, Ag, Pt, Al, Ti, W, Cr, or a mixture thereof.

The recording layer 205 constituting the recording unit 203 is made of a material that changes phase when electric energy is applied, and can also be referred to as a phase change unit in the recording unit 203. 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—. An Sb—Bi—Te based material is used, and more specifically, for example, a GeTe—Sb ₂ Te ₃ based material or a GeTe—Bi ₂ Te ₃ based material can be 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-based material layer, an oxide-nitride-based material layer, or an oxide-fluoride-based material layer, specifically represented by the composition formula (1) or (2). A layer containing material is used. These material layers are preferably used for the dielectric layer 206 because of their high melting point, difficulty in diffusion of atoms in the material layer even when heated, and low thermal conductivity.

  This embodiment will be further described together with its operation method in the examples described later.

  The present invention will be described more specifically.

  First, a nominal composition (in other words, a target composed of an oxide-based material, an oxide-nitride-based material, and an oxide-fluoride-based material used for forming the dielectric layer of the information recording medium of the present invention). For example, the relationship between the composition publicly displayed by the target manufacturer at the time of supply and the analytical composition was confirmed in advance by a test.

In this test, as an example, a sputtering target having a nominal composition represented by (SnO ₂ ) ₃₀ (Ga ₂ O ₃ ) ₄₀ (Si ₃ N ₄ ) ₃₀ (mol%) corresponding to the composition formula (10) is used. Using. The sputtering target was powdered and composition analysis was performed by an X-ray microanalyzer method. As a result, the analytical composition of the sputtering target was obtained as a composition formula represented by the ratio (atomic%) of each element. The analysis results are shown in Table 1. Further, Table 1 also 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 (that is, the analytical composition) of the sputtering target represented by the composition formula (10) almost coincides with the elemental composition (that is, the converted composition) obtained by calculation, and therefore the nominal composition is appropriate. It was confirmed that there was. Therefore, in the following examples, the composition of the sputtering target is expressed by a nominal composition (mol%). The nominal composition of the sputtering target and the composition (mol%) of the oxide-based material layer, oxide-nitride-based material layer, and oxide-fluoride-based material layer formed by sputtering using this sputtering target It was also confirmed that they can be regarded as the same. Therefore, in the following examples, the composition of the layer formed using this sputtering target was determined by indicating the composition of the sputtering target.

Example 1
In Example 1, in the information recording medium shown in FIG. 1 described in Embodiment 1, the first dielectric layer 2 and the second dielectric layer 6 are made of (SnO ₂ ) ₉₅ (AlN) ₅ (mol%). ) Using a sputtering target whose nominal composition is displayed. The first dielectric layer 2 and the second dielectric layer 6 were formed of the same material. Hereinafter, a method for manufacturing the information recording medium of this example will be described. In the following description, the same reference numerals as those of the components shown in FIG. 1 are used.

  First, as the substrate 1, a diameter in which 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 1) of 0.615 μm is provided in advance on one surface. A circular polycarbonate substrate having a thickness of 120 mm and 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 8 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 of 80 nm. The reflective layer 8 was formed in this order by the sputtering method as described below.

As a material constituting the first dielectric layer 2 and the second dielectric layer 6, (SnO ₂ ) ₉₅ (AlN) ₅ (mol%) was used.

  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 above-described material is attached to a film forming apparatus, and the pressure is 0.13 Pa. A film was formed by high-frequency sputtering of 400 W in an atmosphere of a mixed gas of Ar gas and oxygen gas (oxygen gas partial pressure 3%).

The step of forming the recording layer 4 includes 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 100 W DC sputtering was performed in a mixed gas atmosphere of Ar gas and nitrogen gas (nitrogen gas partial pressure 3%) under a pressure of 0.13 Pa. The composition of the recording layer was Ge ₂₇ Sn ₈ Sb ₁₂ Te ₅₃ (atomic%).

The step of forming the light absorption correction layer 7 is performed by attaching a sputtering target (diameter: 100 mm, thickness: 6 mm) made of a material having a composition of Ge ₈₀ Cr ₂₀ (atomic%) to a film forming apparatus, under a pressure of about 0.4 Pa. DC sputtering of 300 W was performed in an Ar gas atmosphere.

  The step of forming the reflective layer 8 is performed by attaching a sputtering target (diameter 100 mm, thickness 6 mm) made of an Ag—Pd—Cu alloy to a film forming apparatus and applying a direct current of 200 W in an Ar gas atmosphere under a pressure of about 0.4 Pa. Sputtering was performed.

  After forming the reflective layer 8, an ultraviolet curable resin was applied on the reflective layer 8. A polycarbonate bonded substrate 10 having a diameter of 120 mm and a thickness of 0.6 mm was adhered onto the applied ultraviolet curable resin. Next, the resin was cured by irradiating ultraviolet rays from the side of the bonded substrate 10, and the bonded substrate 10 was bonded to the reflective layer 8.

  After the bonded substrate 10 was bonded to the reflective layer 8, an initialization process was performed using a semiconductor laser having a wavelength of 810 nm, and the recording layer 4 was crystallized. With the completion of the initialization process, the production of the information recording medium was completed.

(Example 2)
In the information recording medium of Example 2, the nominal composition of the first dielectric layer 2 and the second dielectric layer 6 is indicated by (Ga ₂ O ₃ ) ₈₀ (Si ₃ N ₄ ) ₂₀ (mol%). It was produced in the same manner as in the case of the information recording medium of Example 1, except that the sputtering target was used.

(Example 3)
In the information recording medium of Example 3, the first dielectric layer 2 and the second dielectric layer 6 were sputtered with the nominal composition indicated by (SnO ₂ ) ₅₀ (Si ₃ N ₄ ) ₅₀ (mol%). It was produced in the same manner as the information recording medium of Example 1 except that it was formed using a target.

(Example 4)
In the information recording medium of Example 4, the first dielectric layer 2 and the second dielectric layer 6 are made of (SnO ₂ ) ₃₀ (Ga ₂ O ₃ ) ₄₀ (Si ₃ N ₄ ) ₃₀ (mol%). It was produced in the same manner as in the case of the information recording medium of Example 1 except that it was formed using a sputtering target with the nominal composition displayed.

(Example 5)
In the information recording medium of Example 5, the first dielectric layer 2 and the second dielectric layer 6 were nominally composed of (SnO ₂ ) ₄₀ (Ga ₂ O ₃ ) ₄₀ (SiO ₂ ) ₂₀ (mol%). It was produced in the same manner as in the case of the information recording medium of Example 1, except that it was formed using a sputtering target on which is displayed.

(Example 6)
In the information recording medium of Example 6, the first dielectric layer 2 and the second dielectric layer 6 are made of (SnO ₂ ) ₃₀ (Ga ₂ O ₃ ) ₃₀ (SiO ₂ ) ₂₀ (Si ₃ N ₄ ) ₂₀ It was produced in the same manner as in the case of the information recording medium of Example 1 except that it was formed using a sputtering target whose nominal composition was indicated by (mol%).

(Example 7)
In the information recording medium of Example 7, the first dielectric layer 2 and the second dielectric layer 6 are made of (ZnO) ₄₀ (Ga ₂ O ₃ ) ₄₀ (SiO ₂ ) ₁₀ (Si ₃ N ₄ ) ₁₀ ( This was prepared in the same manner as in the information recording medium of Example 1, except that the sputtering target with the nominal composition displayed in mol%) was used.

(Example 8)
In the information recording medium of Example 8, the nominal composition of the first dielectric layer 2 and the second dielectric layer 6 was indicated by (ZnO) ₂₀ (SnO ₂ ) ₆₀ (BN) ₂₀ (mol%). It was produced in the same manner as in the case of the information recording medium of Example 1 except that it was formed using a sputtering target.

Example 9
In the information recording medium of Example 9, the first dielectric layer 2 and the second dielectric layer 6 are nominally made of (ZnO) ₃₀ (SnO ₂ ) ₃₀ (AlN) ₂₀ (SiO ₂ ) ₂₀ (mol%). It was produced in the same manner as in the case of the information recording medium of Example 1 except that it was formed using a sputtering target whose composition was displayed.

(Example 10)
In the information recording medium of Example 10, the first dielectric layer 2 and the second dielectric layer 6 are made of (ZnO) ₂₀ (SnO ₂ ) ₂₀ (Ga ₂ O ₃ ) ₄₀ (AlN) ₂₀ (mol%). It was produced in the same manner as in the case of the information recording medium of Example 1, except that it was formed using a sputtering target whose nominal composition was displayed.

(Example 11)
In the information recording medium of Example 11, the first dielectric layer 2 and the second dielectric layer 6 were made of (SnO ₂ ) ₇₀ (Al ₂ O ₃ ) ₃₀ (mol%) and a sputtering target whose nominal composition was displayed. It was produced in the same manner as in the case of the information recording medium of Example 1, except that it was formed using

Example 12
In the information recording medium of Example 12, the first dielectric layer 2 and the second dielectric layer 6 are formed using a sputtering target whose nominal composition is indicated by (SnO 2) ₇₀ (AlN) ₃₀ (mol%). It was produced in the same manner as the information recording medium of Example 1 except that it was formed.

(Example 13)
In the information recording medium of Example 13, the first dielectric layer 2 and the second dielectric layer 6 were nominally composed of (SnO2) ₆₀ (Ga ₂ O ₃ ) ₂₀ (Al ₂ O ₃ ) ₂₀ (mol%). It was produced in the same manner as in the case of the information recording medium of Example 1 except that it was formed using a sputtering target whose composition was displayed.

(Example 14)
In the information recording medium of Example 14, the first dielectric layer 2 and the second dielectric layer 6 are represented by (SnO ₂ ) ₄₀ (Ga ₂ O ₃ ) ₄₀ (AlN) ₂₀ (mol%) and the nominal composition. It was produced in the same manner as in the information recording medium of Example 1 except that the sputtering target was used.

(Example 15)
In the information recording medium of Example 15, the first dielectric layer 2 and the second dielectric layer 6 were formed by using a sputtering target having a nominal composition represented by (SnO ₂ ) ₇₀ (LaF ₃ ) ₃₀ (mol%). The information recording medium of Example 1 was produced in the same manner as in Example 1 except that it was used.

(Example 16)
In the information recording medium of Example 16, the first dielectric layer 2 and the second dielectric layer 6 were formed using a sputtering target whose nominal composition was indicated by (ZnO) ₅₀ (CeF ₃ ) ₅₀ (mol%). The information recording medium of Example 1 was manufactured in the same manner as in Example 1 except that the recording medium was formed.

(Example 17)
In the information recording medium of Example 17, the first dielectric layer 2 and the second dielectric layer 6 were nominally composed of (SnO ₂ ) ₃₀ (Ga ₂ O ₃ ) ₄₀ (LaF ₃ ) ₃₀ (mol%). It was produced in the same manner as in the case of the information recording medium of Example 1, except that it was formed using a sputtering target on which is displayed.

(Comparative Example 1)
As the information recording medium of Comparative Example 1, an information recording medium having the configuration shown in FIG. 6 was produced. Here, the first dielectric layer 102 and the second dielectric layer 106 were formed of a sputtering target of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%). Further, the first interface layer 103 and the second interface layer 105 were each 5 nm thick layers made of ZrO ₂ —SiO ₂ —Cr ₂ O ₃ .

The first dielectric layer 102 and the second dielectric layer 106 are formed using a sputtering target (diameter 100 mm, thickness 6 mm) made of (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) with a pressure of 0. 0. It was formed by performing high frequency sputtering at 13 Pa.

The first interface layer 103 and the second interface layer 105 are a sputtering target (diameter: 100 mm, thickness: 6 mm) made of a material having a composition of (ZrO ₂ ) ₂₅ (SiO ₂ ) ₂₅ (CrO ₂ ) ₅₀ (mol%). ) Was attached to a film forming apparatus and formed by high frequency sputtering. The other bonding with the light absorption correction layer 7, the reflection layer 8, and the bonded substrate 10 is the same as that of the information recording medium of Example 1.

(Comparative Example 2)
The information recording medium of Comparative Example 2 is the same as that of Example 1 except that the first dielectric layer 2 and the second dielectric layer 6 are formed using a sputtering target on which the nominal composition of SnO ₂ is displayed. It was produced in the same manner as the information recording medium.

(Comparative Example 3)
The information recording medium of Comparative Example 3 is the same as Example except that the first dielectric layer 2 and the second dielectric layer 6 are formed using a sputtering target in which the nominal composition of only Ga ₂ O ₃ is displayed. 1 was produced in the same manner as in the case of the information recording medium.

(Comparative Example 4)
The information recording medium of Comparative Example 4 is the same as that of Example 1 except that the first dielectric layer 2 and the second dielectric layer 6 are formed using a sputtering target in which the nominal composition of only ZnO is displayed. It was produced in the same manner as the recording medium.

(Comparative Example 5)
In the information recording medium of Comparative Example 5, the first dielectric layer 2 and the second dielectric layer 6 were sputtered with the nominal composition of (SnO ₂ ) ₅₀ (Ga ₂ O ₃ ) ₅₀ (mol%) displayed. It was produced in the same manner as the information recording medium of Example 1 except that it was formed using a target.

  Next, the information recording media of Examples 1 to 17 and Comparative Examples 1 to 5 were evaluated. The evaluation method will be described below. There were three evaluation items: (1) adhesion between the dielectric layer and the recording layer, (2) recording sensitivity, and (3) rewriting performance.

  First, the adhesion of (1) was evaluated based on the presence or absence of peeling under high temperature and high humidity conditions. Specifically, the information recording medium after the initialization process is left in a high-temperature and high-humidity tank at a temperature of 90 ° C. and a relative humidity of 80% for 100 hours, and then the recording layer 4 and the dielectric layers 2 and 6 in contact therewith It was visually observed with an optical microscope whether or not peeling occurred on at least one of the interfaces.

  (2) Recording sensitivity and (3) Repetitive rewriting performance were evaluated by using a recording / reproduction evaluation apparatus and evaluating the optimum power and the number of repetitions at the recording power.

  The signal evaluation of the information recording medium includes a spindle motor that rotates the information recording medium, an optical head that includes a semiconductor laser that emits laser light, and an objective lens that focuses the laser light on the recording layer 4 of the information recording medium. A general information recording system provided was used. Specifically, 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. At this time, the linear velocity for rotating the information recording medium 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 is irradiated toward the information recording medium while performing power modulation between the peak power (mW) at the high power level and the bias power (mW) at the low power level, and the mark length A random signal 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 (jitter at the front end portion of the recording mark) and a jitter value between the rear ends (jitter at the rear end portion of the recording mark) 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 constant value and the peak power is variously changed, 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 this bias power is fixed to Pb and the average jitter value is measured for each recording condition with various changes in peak power, and the peak power is gradually increased, the average jitter value of the random signal reaches 13%. The power 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.

  In this embodiment, the number of repetitions is determined based on the average jitter value. The information recording medium is irradiated with the laser beam power-modulated with Pp and Pb set as described above, and a random signal having a mark length of 0.42 μm (3T) to 1.96 μm (14T) (groove). After recording continuously (by recording) a predetermined number of times on the same groove surface, the average jitter value was measured. The average jitter value was measured when the number of repetitions was 1, 2, 3, 5, 10, 100, 200, 500 times, and 1000 times or more was measured every 1000 times and evaluated up to 10,000 times. The repeated rewriting performance was evaluated by the number of repetitions when the average jitter value reached 13%. The larger the number of repetitions, the higher the repeated rewriting performance. When the information recording medium as described above is used, for example, in an audio / video recorder, the number of repetitions is preferably 10,000 or more.

  Table 2 shows the evaluation results of (1) adhesion, (2) recording sensitivity, and (3) rewriting performance in the information recording media of Examples 1 to 17 and Comparative Examples 1 to 5. For the information recording media of Examples 1 to 17 and Comparative Examples 2 to 6, the atomic% of the material used for the dielectric layer is also shown. Here, the presence or absence of peeling after the high-temperature and high-humidity test is shown as an evaluation result of adhesion. The recording sensitivity showed a set peak power, and was evaluated as good when it was 14 mW or less. The rewrite performance was evaluated as x when the number of repetitions was less than 1000, Δ when 1000 or more and less than 10,000, and ◯ when 10,000 or more.

As apparent from Table 2, first, when the material of the dielectric layers 2 and 6 is SnO ₂ , Ga ₂ O ₃ , ZnO, the adhesion between the recording layer 4 and the dielectric layers 2 and 6 is good. The recording sensitivity was insufficient (Comparative Examples 2 to 5). On the other hand, as in Examples 1 to 17, in the present invention, SiO ₂ , AlN, BN, Si ₃ N ₄ , LaF ₃ , and CeF ₃ are added to the oxide group consisting of SnO ₂ , Ga ₂ O ₃ and ZnO. By mixing within the specified range, good recording sensitivity was obtained.

In consideration of the balance between recording sensitivity and rewriting performance, the ratio of the SnO ₂ , Ga ₂ O and ZnO oxide groups is preferably 50 mol% or more, and SiO ₂ , AlN, BN, Si ₃ N ₄ , It was confirmed that the ratio of LaF ₃ and CeF ₃ is preferably at least 5 mol% in consideration of the recording sensitivity.

  Next, examples of the information recording medium having the configuration shown in Embodiment 2 will be described below.

(Example 18)
The information recording medium of this example is the information recording medium shown in FIG. 2 described in Embodiment 2, and the first dielectric layer 102 uses (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%). The interface layer 103 was formed with a thickness of ₂ to 5 nm using ZrO ₂ —SiO ₂ —Cr ₂ O ₃ . About the structure of those other than this, it produced similarly to the case of the information recording medium of Example 1. FIG. In Example 18, the second dielectric layer 6 disposed on and in contact with the recording layer 4 was formed using the sputtering target of the material used in Example 1.

Example 19
The information recording medium of Example 19 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Example 2. .

(Example 20)
The information recording medium of Example 20 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Example 3. .

(Example 21)
The information recording medium of Example 17 was produced in the same manner as the information recording medium of Example 21, except that the second dielectric layer 6 was formed using the sputtering target of the material used in Example 4. .

(Example 22)
The information recording medium of Example 22 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Example 5. .

(Example 23)
The information recording medium of Example 23 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Example 7. .

(Example 24)
The information recording medium of Example 24 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Example 9. .

(Example 25)
The information recording medium of Example 25 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Example 10. .

(Example 26)
The information recording medium of Example 26 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Example 11. .

(Example 27)
The information recording medium of Example 27 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Example 12. .

(Example 28)
The information recording medium of Example 28 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Example 13. .

(Example 29)
The information recording medium of Example 29 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Example 14. .

(Comparative Example 6)
The information recording medium of Comparative Example 6 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Comparative Example 2. .

(Comparative Example 7)
The information recording medium of Comparative Example 7 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Comparative Example 3. .

(Comparative Example 8)
The information recording medium of Comparative Example 8 was produced in the same manner as the information recording medium of Example 18 except that the second dielectric layer 6 was formed using the sputtering target of the material used in Comparative Example 5. .

  Table 3 shows (1) adhesion, (2) recording sensitivity, and (3) rewriting performance in the information recording media of Examples 18 to 29 and Comparative Examples 6 to 8. The standard of notation here is the same as that shown in Table 2.

As is clear from Table 3, the first dielectric layer 102 and the interface layer 103 are provided between the substrate 1 and the recording layer 4 and the material of the present invention is applied only to the second dielectric layer 6. The same tendency as in Table 2 was also observed. That is, the oxide group composed of SnO ₂ , Ga ₂ O ₃ and ZnO has good adhesion between the recording layer 4 and the dielectric layer 6 but has insufficient recording sensitivity (Comparative Examples 6 to 8). On the other hand, as in Examples 18 to 29, SiO ₂ , AlN, BN, Si ₃ N ₄ , LaF ₃ , and CeF ₃ are defined in the present invention in the oxide group consisting of SnO ₂ , Ga ₂ O ₃ and ZnO. By mixing within the range, good recording sensitivity was obtained.

In consideration of the balance between adhesion and recording sensitivity, the ratio of the oxide group of SnO ₂ , Ga ₂ O ₃ and ZnO is preferably 50 mol% or more, and SiO ₂ , AlN, BN, Si ₃ N ₄ It was confirmed that the ratio of LaF ₃ and CeF ₃ is preferably at least 5 mol% in consideration of the recording sensitivity.

  As in the information recording media of Examples 1 to 29, the above-described oxide-based material layer, oxide-nitride-based material layer, and oxide-fluoride-based dielectric layer formed in contact with the recording layer When the material layer is used, the object that the number of layers can be reduced is achieved, and good rewriting performance is obtained. The present invention is not limited to these examples. In the information recording medium of the present invention, at least one of the layers formed in contact with the recording layer is the above-described oxide-based material layer, oxide-nitride-based material layer, or oxide-fluoride-based material layer. What is necessary is just to be formed.

(Example 30)
In Examples 1 to 29 described above, an information recording medium for recording information by optical means was produced. In Example 30, an information recording medium for recording information by electrical means as shown in FIG. 3 was produced. This is a so-called memory.

The information recording medium 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 recording layer 205 (hereinafter referred to as a phase change portion 205) that functions as a phase change portion with a material of Ge ₃₈ Sb ₁₀ Te ₅₂ (a compound is expressed as Ge ₈ Sb ₂ Te ₁₁ ). .) Is formed in a circular region having a diameter of 0.2 mm so as to have a thickness of 0.1 μm, and (ZnO) ₄₀ (Ga ₂ O ₃ ) ₄₀ (SiO ₂ ) ₁₀ (Si ₃ N ₄ ) ₁₀ (mol%) A dielectric layer 206 functioning as a heat insulating part (hereinafter referred to as a heat insulating part 206) is used in a region of 0.6 mm × 0.6 mm (excluding the phase change part 205). It was formed to have the same thickness as 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) made of a material having a composition of (ZnO) ₄₀ (Ga ₂ O ₃ ) ₄₀ (SiO ₂ ) ₁₀ (Si ₃ N ₄ ) ₁₀ (mol%). (100 mm, thickness 6 mm) 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. In addition, the order of formation of the phase change part 205 and the heat insulation part 206 is not ask | required, either may be performed first. The recording unit 203 is configured by the phase change unit 205 and the heat insulating unit 206. The phase change portion 205 corresponds to the recording layer referred to in the present invention, and the heat insulating portion 206 corresponds to the material layer referred to in the present invention.

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

  It was confirmed by the system shown in FIG. 4 that a phase change occurred in the phase change portion 205 by applying electrical energy to the information recording medium manufactured as described above. The cross-sectional view of the information recording medium shown in FIG. 4 is a cross section obtained by cutting the information recording medium shown in FIG. 3 in the thickness direction along the line II.

  More specifically, as shown in FIG. 4, the two application units 212 are bonded to the lower electrode 202 and the upper electrode 204 with Au lead wires, respectively, so that the electric writing / reading device 214 is passed through the application unit 212. Was connected to an information recording medium (memory). 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 Example 30, the phase change portion 205 had a melting point of 630 ° C., a crystallization temperature of 170 ° C., and a crystallization time of 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 unit 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. During this period, the resistance value decreased, and the phase change portion 205 transitioned from the amorphous phase state to the 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 material having a composition of (ZnO) ₄₀ (Ga ₂ O ₃ ) ₄₀ (SiO ₂ ) ₁₀ (Si ₃ N ₄ ) ₁₀ (mol%) is used as the heat insulating part 206 around the phase change part 205. In the case of forming the layer including it, it was confirmed that a phase change can be caused in the phase change portion 205 by applying electric energy, and a function of recording information can be provided. In view of the recording sensitivity of Examples 1 to 29, this phenomenon is considered to have the same effect even in the oxide material layer and the oxide-fluoride material layer used in Examples 1 to 29.

As in Example 30, around the cylindrical phase change portion 205, (ZnO) ₄₀ (Ga ₂ O ₃ ) ₄₀ (SiO ₂ ) ₁₀ (Si ₃ N ₄ ) ₁₀ (mol%), which is a dielectric, is formed. When the heat insulating portion 206 is provided, it is possible to effectively suppress the current flowing in the phase change portion 205 from escaping to the peripheral portion by applying a voltage between the upper electrode 204 and the lower electrode 202. 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 (ZnO) ₄₀ (Ga ₂ O ₃ ) ₄₀ (SiO ₂ ) ₁₀ (Si ₃ N ₄ ) ₁₀ (mol%) used for the heat insulating portion 206 has a high melting point and is difficult to cause atomic diffusion due to heat, It is possible to apply to such an electrical memory. Further, if the heat insulating portion 206 exists around the phase change portion 205, the heat insulating portion 206 becomes a barrier, so that the phase change portion 205 is substantially electrically and thermally isolated in the plane of the recording portion 203. By utilizing this fact, the information recording medium 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, and to improve the access function and switching function. It becomes possible to make it. Alternatively, a plurality of information recording media themselves can be connected.

  As described above, the information recording medium of the present invention has been described through various embodiments. Both the information recording medium recorded by the optical means and the information recording medium recorded by the electric means are used for the oxidation defined in the present invention. It has not been realized so far by providing a physical material layer, an oxide-nitride material layer, or an oxide-fluoride material layer in contact with the recording layer (applying to a dielectric layer or a heat insulating portion) Therefore, the performance superior to that of the conventional information recording medium can be obtained.

  The information recording medium and the method for manufacturing the same according to the present invention include, as a high-density information recording medium, for example, a write-once information recording such as a DVD-RAM, a DVD +/− RW, a BD (Blu-ray Disk) recording medium, or a BD-R. The present invention can be applied to uses such as a medium, a magneto-optical recording medium, and a memory using electric energy or optical energy.

It is a fragmentary sectional view which shows an example of the information recording medium in Embodiment 1 of this invention. It is a fragmentary sectional view which shows an example of the information recording medium in Embodiment 2 of this invention. It is a perspective view which shows an example of the information recording medium of this invention on which information is recorded by application of 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

DESCRIPTION OF SYMBOLS 1,201 Substrate 2,102 1st dielectric layer 3,103 1st interface layer 4 Recording layer 5,105 2nd interface layer 6,106 2nd dielectric layer 7 Light absorption correction layer 8 Reflective layer 9 Adhesive layer 10 Bonded substrate 20 Groove surface 21 Land surface 32 Exhaust port 33 Gas supply port 34 Anode 35 Substrate 36 Sputtering target 37 Cathode 38 Power source 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 (35)

An information recording medium comprising a substrate and a recording layer, and capable of at least one of recording and reproduction by light irradiation or application of electrical energy,
An information recording comprising: a material layer containing Ga , at least one element selected from the group GL consisting of Al, Si and B; oxygen (O); and optionally containing nitrogen (N). Medium. The material layer has the following composition formula:
M _H O _I L _J N _K (atomic%)
(In the formula, M represents Ga , L represents at least one element selected from the group GL, and H, I, J and K represent 10 ≦ H ≦ 50, 10 ≦ I ≦ 70, 0 <J ≦. 40, 0 ≦ K ≦ 50 is satisfied.)
The information recording medium of Claim 1 containing the material represented by these. The information recording medium according to claim 2, wherein the material layer includes at least one element of Si and Al as the L. The information recording medium according to claim 2, wherein in the material layer, the M further includes Sn, and the L includes at least one element of Si and Al. An information recording medium comprising a substrate and a recording layer, and capable of at least one of recording and reproduction by light irradiation or application of electrical energy,
A material layer comprising at least one element selected from the group GM consisting of Sn, Ga and Zn, at least one element selected from the group GA consisting of oxygen (O) and La or Ce, and fluorine (F). An information recording medium further comprising: The material layer has the following composition formula:
M _H O _I A _D F _E (atom%)
(In the formula, M represents at least one element selected from the group GM, A represents at least one element selected from the group GA, and H, I, D, and E represent 10 ≦ H ≦ 50, 10 ≦ I ≦ 70, 0 <D ≦ 40, 0 <E ≦ 50 is satisfied.)
The information recording medium of Claim 5 containing the material represented by these. The information recording medium according to claim 5, wherein in the material layer, an element selected from the group GM is at least one of Sn and Ga. The information recording medium according to claim 5, wherein in the material layer, an element selected from the group GM is Ga. The information recording medium according to claim 1, wherein phase change occurs reversibly in the recording layer. 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 9, comprising any one material selected from Ag—In—Sb—Te and Sb—Te. The information recording medium according to claim 9 or 10, wherein the recording layer has a thickness of 15 nm or less. The information recording medium according to claim 1, wherein the material layer is formed in contact with at least one surface of the recording layer. A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer are formed in this order on one surface of the substrate. The first dielectric layer and the second dielectric layer The information recording medium according to claim 1, wherein at least one of the material layers is the material layer. A first dielectric layer, an interface layer, a recording layer, a second dielectric layer, a light absorption correction layer, and a reflective layer are formed in this order on one surface of the substrate, and the second dielectric The information recording medium according to claim 1, wherein the layer is the material layer. A method for producing an information recording medium comprising a substrate, a recording layer, and a material layer, wherein at least one of recording and reproduction can be performed by light irradiation or electrical energy application,
Sputtering the material layer using a sputtering target containing Ga, at least one element selected from the group GL consisting of Al, Si and B, and oxygen (O), and optionally containing nitrogen (N). The manufacturing method of the information recording medium characterized by including the process formed by a method. The sputtering target has the following composition formula:
M _h O _i L _j N _k (atom%)
(In the formula, M represents Ga, L represents at least one element selected from the group GL, h, i, j and k are 10 ≦ h ≦ 50, 10 ≦ i ≦ 70, 0 <j ≦). 40, 0 ≦ k ≦ 50 is satisfied.)
The manufacturing method of the information recording medium of Claim 15 containing the material represented by these. The method of manufacturing an information recording medium according to claim 16, wherein the sputtering target contains at least one element of Si and Al as the L. The method of manufacturing an information recording medium according to claim 16, wherein in the sputtering target, the M further includes Sn, and the L includes at least one element of Si and Al. A method for producing an information recording medium comprising a substrate, a recording layer, and a material layer, wherein at least one of recording and reproduction can be performed by light irradiation or electrical energy application,
The material layer includes at least one element selected from the group GM consisting of Sn, Ga and Zn, at least one element selected from the group GA consisting of oxygen (O), La and Ce, and fluorine (F). The manufacturing method of the information recording medium characterized by including the process formed by sputtering method using the sputtering target containing this. The sputtering target has the following composition formula:
M _h O _i A _d F _e (atom%)
(In the formula, M represents at least one element selected from the group GM, A represents at least one element selected from the group GA, and h, i, d, and e are 10 ≦ h ≦ 50, 10 ≦ i ≦ 70, 0 <d ≦ 40, 0 <e ≦ 50 is satisfied.)
The manufacturing method of the information recording medium of Claim 19 containing the material represented by these. The method for manufacturing an information recording medium according to claim 19, wherein the element selected from the group GM is at least one of Sn and Ga in the sputtering target. The sputtering target includes: (a) an oxide of Ga; and (b) at least one of an oxide and a nitride of at least one element selected from the group GL consisting of Al, Si, and B. 15. A method for manufacturing the information recording medium according to 15. The sputtering target is (a) an oxide of at least one element selected from the group GM consisting of Sn, Ga and Zn, and (c) a fluoride of at least one element selected from the group GA consisting of La or Ce. The method of manufacturing an information recording medium according to claim 19. 24. The method of manufacturing an information recording medium according to claim 23, wherein the oxide of an element selected from the group GM in the sputtering target is an oxide of at least one of Sn and Ga. 25. The method of manufacturing an information recording medium according to claim 24, wherein the oxide of an element selected from the group GM in the sputtering target is an oxide of Ga. The method of manufacturing an information recording medium according to claim 22 or 23, wherein the sputtering target contains 50 mol% or more of the oxide of Ga. The method for manufacturing an information recording medium according to claim 23, wherein the sputtering target contains 50 mol% or more of an oxide group of an element selected from the group GM. 28. The method of manufacturing an information recording medium according to claim 27, wherein the sputtering target contains 50 mol% or more of Sn oxide and Ga oxide in total. 23. The sputtering target includes at least one of an oxide and a nitride of at least one element of Si and Al as at least one of an oxide and a nitride of an element selected from the group GL. A method for producing the information recording medium described in 1. The sputtering target has the following composition formula:
(D) _x (E) _100-x (Mol%)
(Wherein D is Ga ₂ O _Three Where E is AlN, Si _Three N _Four , Al ₂ O _Three And SiO ₂ And x satisfies 50 ≦ x ≦ 95. )
The method for producing an information recording medium according to claim 26, comprising a material represented by: The sputtering target has the following composition formula:
(Ga ₂ O _Three ) _a2 (E1) _b (Mol%)
(Where E1 is AlN and Si _Three N _Four At least one of them, a2 satisfies 50 ≦ a2 ≦ 95, and b satisfies 5 ≦ b ≦ 50. Further, a2 + b = 100. )
The manufacturing method of the information recording medium of Claim 30 containing the material represented by these. The sputtering target has the following composition formula:
(D) _x (SiO ₂ ) _y (E1) _100-x-y (Mol%)
(Wherein D is Ga ₂ O _Three Where E1 is AlN and Si _Three N _Four And x and y satisfy 50 ≦ x ≦ 95, 5 ≦ y ≦ 35, and 55 ≦ x + y ≦ 100. )
The manufacturing method of the information recording medium of Claim 30 containing the material represented by these. The sputtering target has the following composition formula:
(D) _x (A) _100-x (Mol%)
(Wherein D is SnO ₂ , Ga ₂ O _Three And at least one oxide selected from ZnO, and A represents LaF _Three And CeF _Three And x satisfies 50 ≦ x ≦ 95. )
The manufacturing method of the information recording medium of Claim 23 containing the material represented by these. In the sputtering target, the D is SnO. ₂ And Ga ₂ O _Three 34. The method of manufacturing an information recording medium according to claim 33, wherein the method is at least one of the above. In the sputtering target, the D is Ga. ₂ O _Three 34. The method of manufacturing an information recording medium according to claim 33.

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