JP5185406B2 - Sputtering target, interface layer film for phase change optical recording medium using the same, method for producing the same, and phase change optical recording medium - Google Patents

Description

  The present invention relates to, for example, a sputtering target used for forming an interface layer film of a phase change optical recording medium, an interface layer film using the sputtering target, a manufacturing method thereof, and a phase change optical recording medium including such an interface layer film. .

  A phase change optical recording film generally has an amorphous atomic arrangement when a portion heated to a melting point or higher is melted and rapidly cooled. Further, when the temperature is kept below the melting point and in the temperature range of the crystallization temperature for a certain time or more, crystallization occurs when the initial state is amorphous (solid phase erasure mode). Depending on the recording film material, a method of crystallizing by heating and melting the vicinity of the non-crystal part of the recording film to the melting point or higher and then slowly cooling it (melting erasure mode) can be used. In the phase change optical recording medium, the intensity of the reflected light from the amorphous part is different from the intensity of the reflected light from the crystal part. Therefore, the intensity of the reflected light is converted into the intensity of an electric signal to read out information.

  In such a phase change optical recording medium, as a method for increasing the amount of information that can be recorded on one recording medium, that is, the recording capacity, a method for reducing the pitch of recording marks in the track direction or a method for narrowing the track pitch. There is a known method to make it. In addition, as a technique for increasing the capacity, a method of providing a plurality of layers for carrying information and superimposing them is known. A medium designed so that two layers can be read and written from one side is called a single-sided double-layered medium, or simply a double-layered medium.

  In particular, in a single-sided dual-layer medium, an information layer (hereinafter referred to as L0 layer) provided closer to the light incident side is necessary for the L0 layer when accessing an information layer (hereinafter referred to as L1 layer) provided far away. In order not to attenuate light more than that, it is necessary to secure a transmittance of approximately 50% or more. For this purpose, in general, the method of reducing the thickness of the recording film of the L0 layer to 10 nm or less, or increasing the transmittance of the interface layer formed before and after the recording film (decreasing the extinction coefficient) There is a way. For example, if the films before and after the recording film are made thin, the holding time required for crystallization becomes long, and disappearance occurs at a normal recording speed. As a countermeasure for this, it is effective to replace a part of the GeSbTe recording film with Sn, Bi, In, Pb or the like.

  In order to ensure the erasure rate of the recording film, it is not sufficient to devise the recording film material, and it is necessary to arrange a film having an effect of promoting crystallization at the interface with the recording film. As such an interface layer, germanium nitride (GeN) is effective. For example, Patent Document 1 describes that a GeN layer or a GeNO layer is provided between a recording layer and a protective layer. However, in the combination of an extremely thin recording film having a thickness of 10 nm or less and an interface layer such as a GeN layer, there is a problem that cross erase occurs and the track pitch cannot be sufficiently narrowed.

On the other hand, silicon carbide (SiC), which has been reported to promote crystallization, has a large light extinction coefficient at the wavelength (405 nm) of laser light used in next-generation high-density optical discs, resulting in very large optical loss. There is. Germanium nitride (GeN) and silicon nitride (SiN _x ) also have optical losses. As an interface layer material having a crystallization promoting function other than GeN, a composite material in which carbide or nitride is mixed with an oxide such as Ta ₂ O ₅ aimed at a material for a protective film of sulfur (S) free is known. However, this also becomes opaque at the wavelength (405 nm) of the laser beam used in the next generation high-density optical disc, and the optical loss increases.

JP 2005-322409 A JP2003-067974

  As described above, in the phase change optical recording medium, in order to secure the erasure rate of the recording film, a film having a crystallization promoting effect is arranged at the interface with the recording film. However, the conventional interface layer material has a large light extinction coefficient at the wavelength (405 nm) of laser light used in the next-generation high-density optical disc, and is a factor that degrades the characteristics and quality of the single-sided double-layer medium. For this reason, the metal compound film constituting the interface layer film of the phase change recording medium having a large recording capacity particularly affects the crystallization promoting function that affects the recording capacity and the reliability of the recording medium. There is a need to achieve both optical properties.

  The present invention has been made to cope with such problems. For example, when used as an interface layer film of a phase change recording medium, a metal compound film having both a crystallization promoting function and an optical property is obtained. It is an object of the present invention to provide a sputtering target capable of the above, an interface layer film for a phase change optical recording medium using the sputtering target, a manufacturing method thereof, and a phase change optical recording medium to which such an interface layer film is applied.

A sputtering target according to an aspect of the present invention is a sputtering target used for forming a metal oxynitride film as an interface layer film in a phase change optical recording medium,
General formula: M (O _1-x N _x ) _z
(In the formula, M represents at least one element selected from Ti, Zr and Hf, and x and z are numbers satisfying 0.1 ≦ x ≦ 0.5 and 0.5 ≦ z ≦ 2.0 (atomic ratio)).
And the total content of Fe, Ni and Co as impurities is 1000 ppm or less.

Interfacial layer film for a phase change optical recording medium according to the embodiment of the present invention, Ri greens and sputtering using a sputtering target according to embodiment of the present invention described above,
General formula: M (O _1-x N _x ) _z
(In the formula, M represents at least one element selected from Ti, Zr and Hf, and x and z are numbers satisfying 0.1 ≦ x ≦ 0.5 and 0.5 ≦ z ≦ 2.0 (atomic ratio)).
It has the composition represented by these .

A method for producing an interface layer film for a phase change optical recording medium according to an aspect of the present invention uses an inert gas atmosphere or an inert gas containing at least one of oxygen and nitrogen using the above-described sputtering target according to the present invention. Sputter-depositing the M element oxynitride film in a gas atmosphere ,
General formula: M (O _1-x N _x ) _z
(In the formula, M represents at least one element selected from Ti, Zr and Hf, and x and z are numbers satisfying 0.1 ≦ x ≦ 0.5 and 0.5 ≦ z ≦ 2.0 (atomic ratio)).
It comprises the process of forming the interface layer film | membrane which has a composition represented by these .

A phase change optical recording medium according to an aspect of the present invention includes a phase change optical recording layer that is reversibly recorded and erased by light irradiation, and an interface disposed along at least one surface of the phase change optical recording layer An interface layer made of a metal oxynitride film formed by sputtering using the sputtering target according to the aspect of the present invention described above ,
The interface layer is
General formula: M (O _1-x N _x ) _z
(In the formula, M represents at least one element selected from Ti, Zr and Hf, and x and z are numbers satisfying 0.1 ≦ x ≦ 0.5 and 0.5 ≦ z ≦ 2.0 (atomic ratio)).
It has the composition represented by these .

  According to the sputtering target of the present invention, for example, when used as an interface layer film of a phase change recording medium, a metal oxynitride film having both a crystallization promoting function and optical characteristics can be obtained. By applying such an interface layer film made of a metal oxynitride film, it becomes possible to improve the characteristics and quality of the phase change recording medium.

It is sectional drawing which shows the structure of the phase change optical recording medium by embodiment of this invention.

Hereinafter, modes for carrying out the present invention will be described. A sputtering target according to the first embodiment of the present invention comprises:
General formula: M (O _1-x N _x ) _z (1)
(In the formula, M represents at least one element selected from Ti, Zr and Hf, and x and z are numbers satisfying 0 <x ≦ 0.7 and 0.5 ≦ z ≦ 2.0 (atomic ratio)).
The oxynitride target having a composition represented by the following formula is suitably used for forming an interface layer film of a phase change optical recording medium.

A sputtering target according to the second embodiment of the present invention is
General formula: (M _1-a Cr _a ) (O _1-x N _x ) _z (2)
(In the formula, M represents at least one element selected from Ti, Zr, and Hf, and a, x, and z are 0.1 ≦ a ≦ 0.5, 0 <x ≦ 0.7, 0.5 ≦ z ≦ 2.0 (atomic ratio). It is a number that satisfies
In the same manner as in the first embodiment, the oxynitride target having a composition represented by the following formula is suitably used for forming an interface layer film of a phase change optical recording medium.

In the sputtering target of each embodiment described above, the M element is at least one element selected from Ti, Zr, and Hf. The M element may be any one of Ti, Zr, and Hf, Ti and Zr, Ti and Hf, two elements Zr and Hf, and three elements Ti, Zr, and Hf. These element M and Cr _{TiO 2, ZrO 2, HfO 2} , Cr 2 O 3, TiN, ZrN, HfN, to form an oxide or nitride in the form of such CrN. When the interface layer is composed of a metal oxide film or metal nitride film formed using these oxide or nitride targets, the light extinction coefficient is small, but the crystallization of the phase change optical recording film is promoted. It was found through experiments by the present inventors that this was not possible.

  Therefore, as a result of examining the properties of a metal oxynitride film formed using a target containing M element or a combination of M element and Cr with oxygen and nitrogen, the light extinction coefficient and the crystallization promoting function were obtained. I found out that I have both. The sputtering target according to the first embodiment makes it possible to obtain a metal oxynitride film having both an extinction coefficient and a crystallization promoting function by combining an oxide of an M element and a nitride. . The sputtering target according to the second embodiment makes it possible to obtain a metal oxynitride film having both an extinction coefficient and a crystallization promoting function by combining an oxide of M element, Cr, and nitride. It is.

  The M element is a metal element mainly constituting an oxynitride film having both an extinction coefficient and a crystallization promoting function when used as an interface layer film of a phase change optical recording medium, for example. First and Second Embodiments Is an essential constituent element of the sputtering target. As shown in the sputtering target of the first embodiment, the metal oxynitride film constituting the interface layer film can be composed only of a composite of an oxide of M element and a nitride. Furthermore, as shown in the sputtering target of the second embodiment, a part of the M element constituting the metal oxynitride film can be replaced with Cr. By replacing part of the M element with Cr, it becomes possible to improve the adhesion of the metal oxynitride film used as the interface layer film to the recording film.

In order to obtain the effect of improving adhesion by Cr, the substitution amount of M element by Cr (value of a in the formula (2)) is preferably in the range of 0.1 to 0.5. If the value of a is less than 0.1, the effect of improving the adhesion of the metal oxynitride film to the recording film cannot be obtained sufficiently. On the other hand, when the value of a exceeds 0.5, the extinction coefficient of the metal oxynitride film increases, and when the metal oxynitride film is applied to the interface layer film of the phase change optical recording medium, the performance is deteriorated. The value of a is 0.2 or more and 0.4
More preferably, it is as follows. In addition, it is preferable that M element at the time of applying Cr is at least 1 sort (s) chosen from Zr and Hf.

  In order to exhibit the above characteristics (extinction coefficient and crystallization promoting function) of the metal oxynitride film, it is important to control the composition ratio of oxygen and nitrogen with respect to the M element in the sputtering target. In the sputtering target according to the first and second embodiments, the value of x in the expressions (1) and (2) is in the range of more than 0 and not more than 0.7. When the value of x exceeds 0.7, the crystallization promoting function of the obtained sputtered film (metal oxynitride film) decreases. That is, the crystallization of the recording film cannot be promoted, and the performance is deteriorated when applied to the use of the interface layer film for phase change optical recording medium. In order to promote crystallization of the resulting recording film, the value of x is more preferably in the range of 0.1 to 0.5.

  Furthermore, in the sputtering target according to the first and second embodiments, the composition ratio of the gas component (oxygen and nitrogen) to the M element (the value of z in the equations (1) and (2)) is in the range of 0.5-2. To do. When the composition ratio (atomic ratio) of the gas component is less than 0.5, the extinction coefficient of the resulting sputtered film increases, and when applied to the interface layer film for phase change optical recording media, the performance is degraded. On the other hand, if the composition ratio (atomic ratio) of the gas components of the sputtering target exceeds 2, abnormal discharge tends to occur when sputtering is performed, and the amount of dust mixed in the sputtered film increases. This is a cause of deterioration in the quality and characteristics of the sputtered film. The composition ratio of the gas component is more preferably in the range of 1 to 2 although it depends on the applied M element.

  The sputtering target of each embodiment described above preferably has a purity of, for example, 95% or more in consideration of the intended use as an interface layer film for a phase change optical recording medium. The purity mentioned here is a value obtained by subtracting the content (mass%) of impurity elements such as Fe, Ni, Co, Mn, Al, Cu, Na, and K and the total amount of sintering aid from 100%. It is shown. The purity of the sputtering target is more preferably 97% or more. Of the above-described impurity elements, Fe, Ni, and Co in particular cause abnormal discharge during sputtering, so the alloy content of these elements is preferably set to 1000 ppm or less. That is, the amount of dust generated due to abnormal discharge can be reduced by setting the total content of Fe, Ni and Co in the sputtering target to 1000 ppm or less.

  The purity and the amount of impurity elements of the above-described constituent materials are high frequency inductively coupled plasma emission-mass spectrometry (ICP analysis), nitrogen as a gas component is an inert gas melting-heat conduction method, and oxygen is an inert gas melting- It can be measured using an infrared absorption method. Specifically, samples are cut out from five or more locations of the sputtering target. Select samples so that there is no bias and cut out from more than 5 locations for evaluation. Quantitative analysis of each sample is performed by ICP analysis, and an average value of these measured values is obtained. When evaluating the sputtering target before use, a target larger than the target dimension may be produced, and the sample may be cut out and evaluated so as not to be biased from the outer peripheral portion.

  The sputtering target by each embodiment mentioned above can be produced as follows, for example. In preparing the oxynitride sputtering target, first, an M element oxide powder and a nitride powder, and if necessary, a Cr oxide powder and a nitride powder were prepared so as to have a predetermined composition ratio. Then, it mixes uniformly using a ball mill etc. Either a dry method or a wet method may be applied. Among these, it is preferable to apply dry mixing with a simple process. The container material of the mixing apparatus to be used and the material of the media such as balls are not particularly limited as long as the sputtering target to be produced has a desired purity.

  Moreover, the raw material powder used for the production of the sputtering target (sintered body) is not particularly limited, and a commercially available metal oxide powder or metal nitride powder can be used. In order to obtain a sintered body, the purity of the raw material powder is preferably 99% or more. The purity of the raw material powder is more preferably 99.5% or more. The average particle size of the raw material powder is preferably 75 μm or less, more preferably 50 μm or less. Furthermore, in order to adjust the oxygen and nitrogen contents of the sputtering target, a metal powder (a simple powder or alloy powder of M element or Cr) may be used in combination as a raw material powder.

  Next, a mixed powder of M element oxide powder and nitride powder, and optionally mixed powder containing Cr oxide powder and nitride powder is temporarily formed with a press molding machine or the like. Sintering is performed in a sintering furnace. The atmosphere during normal pressure sintering is not particularly limited, and may be an ordinary atmospheric atmosphere. When producing a large-sized sputtering target, it is preferable to perform temporary molding by CIP. Furthermore, in order to increase the sintered density, the mixed powder may be filled into a carbon mold and the like and may be pressure sintered using a hot press machine. Moreover, you may produce a sintered compact by HIP.

  The sintering temperature of the mixed powder is preferably 800 ° C. or higher. When the sintering temperature is less than 800 ° C., the relative density becomes, for example, 60% or less, and a high-density sputtering target cannot be obtained. The sintering temperature is more preferably 900 ° C. or higher, and further preferably 1000 ° C. or higher. Since the sintering of the mixed powder needs to be performed at a temperature lower than the melting point of each raw material (M element, Cr oxide or nitride), the sintering temperature is preferably 2000 ° C. or lower. The holding time depending on the sintering temperature is preferably 1 hour or longer, more preferably 2 hours or longer. If the cooling rate after sintering is too high, defects such as cracks and cracks are likely to occur in the sintered body. Therefore, the cooling rate is preferably less than 600 ° C./hour, more preferably less than 300 ° C./hour. .

  The above-described sintered body is processed into a desired shape by dry or wet machining, and further bonded to a backing plate for cooling the heat during sputtering, if necessary. In this way, the sputtering target according to the first and second embodiments is obtained. The material of the backing plate is generally Al or Cu. Further, general diffusion bonding, solder bonding, or the like can be applied to the bonding with the backing plate. When applying solder joint, it joins with a backing plate via the well-known In type or Sn type joining material. The joining temperature is preferably 600 ° C. or lower. The shape of the sputtering target can be appropriately selected depending on the sputtering apparatus to be used.

  Next, an embodiment of an interface layer film for a phase change optical recording medium and a manufacturing method thereof according to the present invention will be described. The interfacial layer film according to the embodiment of the present invention uses the sputtering target according to the first embodiment or the sputtering target according to the second embodiment described above, and is inert in an inert gas atmosphere or containing at least one of oxygen and nitrogen. It can be obtained by sputtering film formation in a gas atmosphere.

  In general, when an oxide-based or nitride-based sputtering target is used, film formation is performed using a high-frequency sputtering apparatus. Even when an oxynitride sputtering target is used, it is preferable to form a film using a high-frequency sputtering apparatus. The film forming atmosphere may be only an inert gas such as Ar. However, when oxygen deficiency or nitrogen deficiency occurs, oxygen or nitrogen is assisted, and the film is formed in a mixed atmosphere of an inert gas such as Ar and oxygen or nitrogen. It is preferable to do. The substrate temperature is not particularly limited, but is usually set from room temperature to about 300 ° C.

The interface layer film for the phase change optical recording medium thus obtained, that is, the M element oxynitride film or the M element and Cr composite oxynitride film reflects the composition of the sputtering target,
General formula: M (O _1-x N _x ) _z (1)
(In the formula, M represents at least one element selected from Ti, Zr and Hf, and x and z are numbers satisfying 0 <x ≦ 0.7 and 0.5 ≦ z ≦ 2.0 (atomic ratio)).
Or general formula: (M _1-a Cr _a ) (O _1-x N _x ) _z (2)
(In the formula, M represents at least one element selected from Ti, Zr, and Hf, and a, x, and z are 0.1 ≦ a ≦ 0.5, 0 <x ≦ 0.7, 0.5 ≦ z ≦ 2.0 (atomic ratio). (Satisfied number)
It has the composition represented by these.

  As described above, the interface layer film having the composition represented by the formula (1) or the formula (2) is compared with the oxide film or nitride film of Ti, Zr, Hf, or the nitride film or oxynitride film of Ge. In addition to being excellent in the crystallization promoting function of the recording film, the extinction coefficient of light, particularly the extinction coefficient at the wavelength (405 nm) of laser light used in the next-generation high-density optical disc is small. Therefore, such an interface layer film (metal oxynitride film) is effectively used for a phase change optical recording medium, particularly a phase change optical recording medium having a large recording capacity such as a single-sided double layer medium.

  Next, an embodiment of the phase change optical recording medium of the present invention will be described. Here, an embodiment in which the sputtering target of the above-described embodiment and the interface layer film using the sputtering target are applied to a phase change optical recording medium will be described. The phase change optical recording medium may be a single-layer medium or a single-sided double-layer medium. In any case, the phase change optical recording medium has, as a basic structure, a phase change optical recording layer that is reversibly recorded / erased by light irradiation, and an interface layer disposed along at least one surface thereof. It has.

  FIG. 1 is a cross-sectional view showing a configuration of a phase change optical recording medium according to an embodiment of the present invention. A phase change optical recording medium 1 shown in FIG. 1 has a transparent substrate 2 such as a polycarbonate substrate disposed on the light incident side. On this transparent substrate 2, a first dielectric layer 3, a first interface layer 4, a phase change optical recording layer 5 that is reversibly recorded / erased by light irradiation, a second interface layer 6, a second The dielectric layer 7 and the metal reflection film 8 are sequentially laminated.

  As the phase change optical recording layer 5, GeSbTeBi, GeSbTe, GeBiTe, GeSbTeSn, AgInSbTe, InSbTe, AgInGeSbTe, GeInSbTe, or the like is used. Between the phase change optical recording layer 5 and the first dielectric layer 3 and the second dielectric layer 7, there are interface layers 4 and 6 made of the interface layer film (metal oxynitride film) of the above-described embodiment. Each is arranged. The interface layer may be disposed only on one side of the phase change optical recording layer 5. According to this embodiment, the characteristics, reliability, quality, and the like of the phase change optical recording medium 1 can be improved based on the characteristics of the interface layer film (metal oxynitride film) described above.

The first and second dielectric layers 3 and 7 include, for example, ZnS—SiO ₂ , SiO ₂ , SiO, Si—O—N, Si—N, Al ₂ O ₃ , Al—O—N, TiO ₂ , Ta—N, Ta ₂ O ₅ , Ta—O—N, Zn—O, ZnS, ZrO ₂ , Zr—O—N, Zr—N, Cr—O, Mo—O, W—O, V—O, Nb—O, Ta—O, In—O, Cu—O, Sn—O, In—Sn—O, and the like, dielectric materials having substantially transparent and appropriate thermal conductivity, and mixtures thereof, A laminated film of a dielectric material or the like can be applied. Further, for example, Ag, Al, Au, Cu and alloys containing these as main components are used as the constituent material of the metal reflection film 8.

  Next, specific examples of the present invention and evaluation results thereof will be described.

Examples 1-9
First, TiO ₂ powder, TiO powder, ZrO ₂ powder, HfO ₂ powder, TiN powder, ZrN powder, and HfN powder having a purity of 99% or more and an average particle diameter of 2 μm were prepared. Further, Ti, Zr, and Hf metal powders having a purity of 99% or more and an average particle diameter of 10 μm were prepared. These powders were prepared so as to satisfy the compositional ratios shown in Table 1, and then put into a resin ball mill container together with alumina balls and mixed for 24 hours.

  Next, each mixed powder was filled in a rubber, and temporary molding was performed at a pressure of 100 MPa using an isostatic press (CIP). Furthermore, each of these compacts was sintered under normal pressure in an air atmosphere under conditions of a sintering temperature of 1300 ° C. and a holding time of 5 hours. The heating rate was 600 ° C./hour, and the cooling rate was 300 ° C./hour. Each obtained sintered body was machined into a disk shape (diameter 127 mm × thickness 5 mm), and then joined to an oxygen-free copper backing plate by applying a solder joining method. In this way, sputtering targets having the target composition were prepared. Each of these sputtering targets was subjected to the characteristic evaluation described later.

Comparative Examples 1-6
In Example 1 described above, a sputtering target was produced in the same manner as in Example 1 except that the preparation composition and purity of each raw material powder were changed. In Comparative Example 6, GeN was used. Each of these sputtering targets was also subjected to the characteristic evaluation described later.

  Next, using the sputtering targets according to Examples 1 to 9 and Comparative Examples 1 to 6 described above, sputtering film formation was performed as follows. Using a high frequency sputtering apparatus, an interface layer film having a thickness of 100 ± 10 nm was formed on a glass substrate under the conditions of a substrate temperature of 25 ° C. and an argon atmosphere (0.5 MPa). The film thickness was measured using a tactile film thickness measuring instrument (α step). The properties of the interface layer film thus sputtered and the dust generation rate were measured and evaluated. The results are shown in Table 2.

  The film properties were evaluated by measuring the extinction coefficient of a single layer film formed on a glass substrate using an ellipsometer. The dust generation rate was evaluated by measuring the average number of dust particles having a size of 0.5 μm or more mixed in the film by performing film formation five times using the same substrate as described above. In addition, it was confirmed that the film composition was almost the same as the target composition.

Furthermore, in measuring and evaluating the crystallization promoting function of the interface layer film, a polycarbonate (PC) having a thickness of 0.59 mm formed by injection molding was used as a substrate. An interfacial layer film was formed on this substrate, and then a film having a composition of Ge ₁₀ Sb ₃₀ Te ₆₀ was formed as a recording film. Further, a similar interface layer film was formed on the recording film to obtain a sample for evaluation. The film thickness was 100 ± 10 nm in all cases. When the recording film in an amorphous state is crystallized with temperature, the transmittance rapidly decreases. The slope of the decrease in transmittance was evaluated as the crystallization speed (crystallization promoting function). It can be considered that the smaller the temperature difference is, the more effective the crystallization is. The transmittance of the sample from room temperature to 300 ° C. was measured at a heating rate of 10 ° C./min.

  As is apparent from Table 2, the metal oxynitride film formed using each sputtering target of Examples 1 to 9 has a crystallization rate compared to the film formed using the sputtering target of Comparative Examples 1 to 6. Is fast (excellent in crystallization promoting function) and has a good extinction coefficient. Furthermore, when the sputtering target with a large z value of the target composition according to Comparative Example 3 or the sputtering target with the total content of Fe, Ni, and Co according to Example 9 exceeds 1000 ppm, the crystallization speed of the sputtered film is fast. On the other hand, it can be seen that dust due to abnormal discharge increases. Therefore, in order to improve the practicality of the sputtering target, the total content of Fe, Ni, and Co is preferably set to 1000 ppm or less.

Examples 10-16
First, ZrO ₂ powder, HfO ₂ powder, Cr ₂ O ₃ powder, ZrN powder, HfN powder, and CrN powder having a purity of 99% or more and an average particle diameter of 50 μm were prepared. Further, Zr, Hf, and Cr metal powders having a purity of 99% or more and an average particle diameter of 30 μm were prepared. These powders were prepared so as to satisfy the compositional ratios shown in Table 3, and then put into a resin ball mill container together with alumina balls and mixed for 24 hours.

  Next, each mixed powder was filled in a rubber, and temporary molding was performed at a pressure of 100 MPa using an isostatic press (CIP). Further, these compacts were sintered under atmospheric pressure in the atmosphere at a sintering temperature of 1300 ° C. and a holding time of 5 hours. The heating rate was 600 ° C./hour, and the cooling rate was 300 ° C./hour. Each obtained sintered body was machined into a disk shape (diameter 127 mm × thickness 5 mm), and then joined to an oxygen-free copper backing plate by applying a solder joining method. In this way, sputtering targets having the target composition were prepared. Each of these sputtering targets was subjected to characteristic evaluation.

Comparative Examples 7-13
In Example 10 described above, a sputtering target was prepared in the same manner as in Example 10 except that the preparation composition and purity of each raw material powder were changed. In Comparative Example 13, GeN was used. Each of these sputtering targets was also subjected to characteristic evaluation.

  Next, sputter film formation was performed in the same manner as in Example 1 using the sputtering targets according to Examples 10 to 16 and Comparative Examples 7 to 13 described above. The characteristics and dust generation rate of the interface layer film thus formed by sputtering were measured and evaluated in the same manner as in Example 1. Furthermore, the adhesion between the sputtered interface layer film and the recording film was measured and evaluated. These measurement results are shown in Table 4.

In evaluating the adhesion to the recording film, a PC substrate having the same characteristics as the interface layer film was used. An interfacial layer film was formed on this substrate, and then a film of Ge ₁₀ Sb ₃₀ Te ₆₀ composition was formed as a recording film. The film thickness was 100 ± 10 nm in all cases. The evaluation method is to form a film 5 times on each substrate, heat-treat in a vacuum atmosphere at a temperature of 350 ° C. and a time of 5 minutes, and then at least 2 μm out of 5 samples with a size of 0.5 μm or more. The case where no blistering, peeling or cracking occurred was evaluated as x, the case where it occurred in one sample was evaluated as Δ, and the case where it did not occur was evaluated as ○.

  As is apparent from Table 4, the metal oxynitride film formed using each sputtering target of Examples 10 to 16 has a crystallization rate compared to the film formed using the sputtering target of Comparative Examples 7 to 13 Is fast (excellent in crystallization promoting function), and the extinction coefficient and the adhesion to the recording film are also good. It was confirmed that the composition of each film was almost equivalent to the target composition.

  DESCRIPTION OF SYMBOLS 1 ... Phase change optical recording medium, 2 ... Transparent substrate, 3 ... 1st dielectric layer, 4 ... 1st interface layer, 5 ... Phase change optical recording layer, 6 ... 2nd interface layer, 7 ... 2nd Dielectric layer, 8 ... metal reflective film.

Claims (5)

A sputtering target used for forming a metal oxynitride film as an interface layer film in a phase change optical recording medium,
General formula: M (O _1-x N _x ) _z
(In the formula, M represents at least one element selected from Ti, Zr and Hf, and x and z are numbers satisfying 0.1 ≦ x ≦ 0.5 and 0.5 ≦ z ≦ 2.0 (atomic ratio)).
And a total content of Fe, Ni and Co as impurities is 1000 ppm or less. The sputtering target according to claim 1, wherein
A sputtering target having a purity of 95% or more. An interface layer film for a phase change optical recording medium formed by sputtering film formation using the sputtering target according to claim 1 or 2 ,
General formula: M (O _1-x N _x ) _z
(In the formula, M represents at least one element selected from Ti, Zr and Hf, and x and z are numbers satisfying 0.1 ≦ x ≦ 0.5 and 0.5 ≦ z ≦ 2.0 (atomic ratio)).
An interface layer film for a phase change optical recording medium, characterized by having a composition represented by: Using the sputtering target according to claim 1 or 2, the M element oxynitride film is formed by sputtering in an inert gas atmosphere or an inert gas atmosphere containing at least one of oxygen and nitrogen .
General formula: M (O _1-x N _x ) _z
(In the formula, M represents at least one element selected from Ti, Zr and Hf, and x and z are numbers satisfying 0.1 ≦ x ≦ 0.5 and 0.5 ≦ z ≦ 2.0 (atomic ratio)).
A method for producing an interface layer film for a phase change optical recording medium, comprising the step of forming an interface layer film having a composition represented by : A phase change optical recording layer that is reversibly recorded and erased by light irradiation; and
An interface layer disposed along at least one surface of the phase change optical recording layer, the interface comprising a metal oxynitride film formed by sputtering using the sputtering target according to claim 1 or 2. Comprising a layer ,
The interface layer is
General formula: M (O _1-x N _x ) _z
(In the formula, M represents at least one element selected from Ti, Zr and Hf, and x and z are numbers satisfying 0.1 ≦ x ≦ 0.5 and 0.5 ≦ z ≦ 2.0 (atomic ratio)).
A phase change optical recording medium having a composition represented by:

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