JP2000264731A - Sintered compact and its production, deposition method using the sintered compact and film formed by the sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sintered compact target capable of forming a good quality insulative thin film by a DC sputtering method by mixing an insulative material which is an essential component and a conductive material which is carbon free of a diamond structure or a conductive inorganic compound exclusive of metal, firing the mixture and making the electric resistivity of the sintered compact lower than the electric resistance of the insulative material. SOLUTION: An oxides, such as SiO2, nitride, such as Si3N4, and chalcogen, such as ZnS, are used alone or as a mixture for the insulative material. The electrical conductivity of carbon is 10 to 10 Ωcm order in the case of graphite or amorphous carbon having the electrical conductivity. The conductive inorganic compounds include tin oxide, indium oxide, indium-tin oxide, etc. The content of the carbon free of the diamond structure is specified to <=40 vol.% when the carbon is used. The insulative material and the conductive material are mixed in the form of a powder and granular material and the grain size thereof is preferably <=10 μm. The firing is executed below the reaction temperature of the respective components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered body useful for forming a dielectric thin film by, for example, direct current sputtering, a film formed by using the sintered body, and more particularly to recording of an optical recording medium. The present invention relates to a sintered body useful for forming a protective layer formed adjacent to a layer, and further relates to a method for forming a protective layer having a high film forming rate, a small amount of incident heat on a substrate, and a uniform thickness.

[0002]

2. Description of the Related Art The formation of a dielectric thin film as a protective layer is employed not only in optical recording media but also in electronic components and various other fields. For example, in a magneto-optical recording medium, a protective layer is provided so as to sandwich the magnetic recording layer in order to prevent oxidation of the recording layer. This protective layer is required to prevent oxygen from entering the magnetic recording layer, and to have heat resistance and not deteriorate by laser light.
The film is formed of a nitride by a reactive sputtering method. The dielectric thin film is not limited to a nitride film, and an oxide film, a sulfide film, or the like is known and used depending on the purpose or application.

[0003] Such a dielectric thin film (insulating thin film) is formed by a reactive sputtering method. In general, a DC sputtering method and a high-frequency sputtering method are known as typical sputtering methods. In the DC sputtering method, N ₂ or O ₂ or the like is mixed and introduced into an inert gas such as Ar under reduced pressure, and a DC high voltage is applied between electrodes to perform glow discharge. As a result, the inert gas is ionized and collides with the cathode side at a high speed, causing the target placed on the cathode to fly out, and the ejected substances are deposited on the substrate as nitrides, oxides, and sulfides to form a thin film. Is formed. In the high-frequency sputtering method, in place of the DC high voltage applied to cause glow discharge in the DC sputtering method described above, 50K is used.
A thin film is formed in the same manner except that high-frequency glow discharge is caused by applying a high-frequency voltage of Hz or more.

The direct current sputtering method and the high frequency sputtering method have both advantages and disadvantages.
However, the high frequency sputtering method is expensive in terms of equipment cost because the power supply configuration is more complicated than the DC sputtering method, and it is difficult to obtain a stable high frequency current in terms of power supply reliability and maintenance. There are problems in running the high-frequency power supply, such as complicated handling. Further, there are problems in that the film formation rate is slower than the DC sputtering method from the viewpoint of performance, and it is difficult to deal with a plastic substrate such as a plastic substrate which is easily deformed due to a large amount of heat incident on the substrate. On the other hand, the direct-current sputtering method has an advantage that it can be applied to various works such as a large area.

[0005] For these reasons, attempts have been made to form a film by a DC sputtering method on an insulating material which has been conventionally formed by a high frequency sputtering method. That is, attempts to switch the high-frequency sputtering method to the direct-current sputtering method include (1) a method of imparting conductivity to a target material to enable direct-current sputtering, and (2) a method of improving a direct-current power supply waveform. (1)
The combination of the method (2) is being promoted.

As means for reducing the resistance by imparting conductivity to the target material in the above (1), a material having lower electric resistance (typically, Cr) than the main material (Si) is used as the main material (Si). Mixing method (Japanese Unexamined Patent Application Publication No.
No.), low resistance materials (P, B) as main materials (Si)
(JP-A-5-36142),
A method in which a part (oxygen component) of a main material (PLZT / PZT-based) is deleted to reduce the resistance (Japanese Unexamined Patent Publication No. Hei 6-330)
297) is known.

On the other hand, as an attempt of the above (2), a method of applying a DC voltage intermittently instead of continuously applying a DC voltage (Japanese Patent No. 2578815) or a method of applying a negative voltage intermittently (JP-A-8-67980) and the like have attempted to prevent abnormal discharge such as arcing. Regarding the attempt from the power supply, if the target remains insulative, it is necessary to cancel the charge on the surface of the target. Therefore, the test is performed simultaneously with the reduction of the resistance of the target material, or a potential for reverse bias is applied ( Means such as JP-A-7-90573) are taken.

However, even when the target is made to have low resistance by the above method (1) and is initially made conductive, the reactive gas used during film formation, such as oxygen or nitrogen, causes the reaction to progress with time. There are problems such as a change in the conductivity of the target surface, or a change in the conductivity of the surface due to the reaction with atmospheric oxygen when the vacuum chamber is exposed to the atmosphere. To solve this problem, Japanese Patent Application Laid-Open No. 7-180
No. 045 discloses a target containing amorphous carbon and at least 35% by volume of yttria, based on the total weight ratio of the target, as a conductive target for DC magnetron sputtering. Here, as a method for forming amorphous carbon, an organic binder is formed by baking an organic binder to scatter components other than carbon by thermal decomposition. After the components other than carbon are scattered, a carbon film is formed on the holes, and the target becomes conductive. Further, the density of the target is about 45 to 70% of the theoretical value.

According to this conductive target, when the material having conductivity is carbon, there is no solid oxide or nitride of carbon, so that the change in conductivity of the target surface seems to be small. However, in the present invention, since the holes after the components other than carbon are scattered, abnormal discharge may occur. Further, since the mechanical strength is low, the sintered body is broken at the time of bonding for bonding the backing plate to the sintered body, or a high-power sputter (for example, 500
If an output of about W or more is assumed), there is a concern that problems such as high-speed film formation cannot be realized due to cracking of the target.

In the method (2), sputtering is performed by applying a DC voltage intermittently, applying a reverse bias voltage intermittently at a constant period, applying a reverse bias potential, or the like. Inevitably complicates the equipment.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a sintered target capable of forming a high-quality insulating thin film by a DC sputtering method, and a sintered target thereof. Is to provide a film forming method using the same.

[0012]

Means for Solving the Problems The present inventors considered the following as a target suitable for the DC sputtering method. That is, as described above, an attempt to reduce the resistance of a target in order to perform direct current sputtering of an insulating material or a material having a high resistance has been already known. It has already been pointed out that even if this contributes to lowering the resistance, the resistance tends to change with time as the sputtering reaction proceeds. That is, for example, an increase in surface resistance due to generation of an oxide, or a change in the doping amount of a target due to a difference in the sputter yield of an over-doped substance. Thus, the present inventors
It was considered that a configuration in which the electrical resistance of the target material surface does not change over time should be developed. The present invention has been made based on such considerations.

Therefore, according to the present invention, first, a material having an insulating property, which is a main component, and a material having a conductive property of a conductive inorganic compound other than carbon or metal which does not contain a diamond structure are mixed, A sintered body characterized by being fired and having an electric resistivity of the obtained sintered body lower than an electric resistivity of the insulating material before sintering.

Second, the first sintered body is characterized in that the substance having an insulating property is a mixture of zinc sulfide and silicon dioxide, and the material having a conductive property is carbon having no diamond structure. Provided.

Third, there is provided the above-mentioned second sintered body, characterized in that the content of carbon which does not include a diamond structure, which is a material having conductivity, in the whole sintered body is 40% by volume or less. Is done.

Fourth, in the process of mixing and firing a material having an insulating property as a main component and a conductive material of a conductive inorganic compound other than carbon or metal that does not have a diamond structure, the insulating property is reduced. Wherein the sintering is carried out at a temperature lower than the mutual reaction temperature of the substance having the above-mentioned and the material having the electric conductivity.

Fifthly, there is provided a method for producing the above-mentioned fourth sintered body, characterized in that carbon having no diamond structure is used as a conductive material and firing is performed in a non-oxidizing atmosphere.

Sixth, a direct current is applied by using a sintered body target obtained by joining any of the first to third sintered bodies and the sintered bodies obtained in the fourth and fifth aspects on a metal base material. A film forming method characterized by forming a film by a sputtering method is provided.

Seventh, there is provided the sixth film forming method, wherein DC sputtering is performed in an atmosphere of a reactive gas containing at least oxygen.

Eighth, there is provided the sixth or seventh film forming method, wherein the substrate to be formed is a plastic substrate.

Ninth, the amount of carbon contained in the film formed on the substrate is 5% by weight or less, and the film is formed by the film forming method according to any one of the above sixth to eighth aspects. A membrane is provided.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. As a method of expressing the material having an insulating property to lower the resistance according to the present invention, carbon or tin oxide (SnO ₂ ) containing no diamond structure, indium oxide (In) is used as the material having the insulating property (main component). ₂ O ₃ ) or another material having conductivity of a conductive inorganic compound other than metal, such as indium-tin oxide (In ₂ O ₃ -SnO ₂ ), is mixed and sintered, and the main component is electric resistivity. A method of obtaining a sintered body having an electric resistivity lower than the electric resistivity of the above-described method is considered. In particular, in the case of carbon not containing a diamond structure,
It has conductivity, is chemically stable, does not form oxides on its surface, does not deteriorate its reliability even when it enters the film, has the lowest sputter yield, has lubricity, and has an abundance on the earth. Because of its large number, it has advantages such as low cost and can be said to be the most suitable conductive material for mixing.

That is, the conductivity of carbon is diamond
With a structure, the specific resistance is 10¹³-10¹⁴Ωcm Oh
But 10% for graphite and amorphous carbon.^-Four~
10 ^-3It is on the order of Ωcm and has conductivity. Grapha
The unit is connected to the direction parallel to the crystal orientation (a-axis direction).
Specific resistance is different in the direction perpendicular to the crystal orientation (c-axis direction)
However, since they are mixed and crushed, the orientation direction does not align.
The conductivity is maintained. Also, target for sputtering
Even if the surface is oxidized as carbon monoxide (C
O) or carbon dioxide (CO_Two) And the surface oxide layer
CO or CO_TwoOf gas
It is evacuated as it is, and does not cause the surface conductivity to change with time. Ma
The sputtering characteristic is ion energy of 500 eV.
Sputtering yield by Ar with
small. (3.8 / 100 of Ag, 1/4 or less of Si
is there. ) (Tatsuo Asamaki: "Basics of Thin Film Production", 6th printing, P12
8) Furthermore, although it usually takes several hours to manufacture a sintered body,
Since carbon has lubricity, it can be mixed in a short time.

During the production of the sintered body, both the substance having the insulating property (component a), which is the main component, and the substance having the conductivity (component b) need to be mixed in the form of powder and granules. . Both the component a and the component b have a particle size of 10 μm or less, preferably 3 to 8 μm, and they are desirably mixed in the same size. As the dielectric layer material having an insulating property, a transparent and thermally stable material is preferable. For example, SiO ₂ , SiO, Al ₂ O ₃ , GeO ₂ , Ta _{2
O 5, TiO 2, MoO 2} , WO 3, oxides such as _{ZrO 2, Si 3 N 4,} AlN, BN, nitrides such as TiN, Z
Chalcogenides such as nS, ZnSe, ZnTe and the like can be mentioned, and these can be used alone or as a mixture.

In recent years, a mixture of zinc sulfide and silicon dioxide is a material which has been most frequently used as a protective layer of a phase change type recording layer of an optical disk. Zinc sulfide, which is a main component among them, easily interacts with humidity and moisture, and is very troublesome to handle. Usually, when molding, an organic binder or an aqueous binder is often used,
It is conceivable that even when the organic matter evaporates, it interacts even with water that aggregates from the atmosphere. However, when carbon is used as the conductive material according to the present invention, since carbon not containing the diamond structure has a self-lubricating property, an organic binder or an aqueous binder is required for mixing, stirring and grinding. In addition to being able to mix and stir sufficiently, the raw materials are not agglomerated at the time of molding, and a uniform pressure can be given without concentration of pressure only on a part. Furthermore, most optical disk substrates are plastic substrates. Currently, the substrates are formed by high-frequency sputtering, and problems such as thermal deformation of the substrates due to incident heat due to high-frequency sputtering have been pointed out. However, according to the present invention, such adverse effects are prevented from occurring.

The content of carbon, which does not contain a diamond structure, which is a conductive material in the sintered body, is determined in consideration of making the sintered body target suitable for DC sputtering. The upper limit is 40% by volume. The reason for setting the content to 40% by volume or less is as follows. When the film formation rate of high-frequency sputtering is used as a reference, the carbon amount becomes the same as the value of the film formation rate when the film is formed by DC sputtering at the value where the concentration becomes this concentration. Disappears.
When the film forming speeds are the same, the merit of lowering the substrate temperature substantially disappears at the same time. Therefore, it is desirable that the content of carbon, which does not include the diamond structure, which is a conductive material in the sintered body, be 40 vol% or less (24 wt% or less in terms of weight ratio when the specific gravity is 1.8). .

The firing conditions for obtaining the sintered body of the present invention include:
Under the temperature conditions, it is desirable to perform the firing at a temperature lower than the mutual reaction temperature of each component in order to surely obtain the target in the firing process. When carbon not containing a diamond structure is used as an atmosphere condition, it is about 50 in the presence of oxygen such as in air.
Since the reaction occurs at 0 ° C. or higher, it is desirable to perform firing in a non-oxidizing atmosphere such as in nitrogen or a rare gas. The ambient conditions include SnO ₂ , In ₂ O ₃ , In ₂ O ₃
Inert atmosphere when using a -SnO _2, or to calcination in a non-oxidizing atmosphere is preferable.

The sintered body obtained as described above is bonded on a metal base and used as a sintered body target. From the viewpoint of forming a film by a sputtering method using this target, the sputtering yield is not limited to any of the direct current sputtering method and the high frequency sputtering method. It is the lowest material and does not easily enter the formed film.

Further, by forming a film by a reactive direct current sputtering method using a reactive gas containing at least oxygen together with a rare gas such as Ar, the content of carbon in the film can be reduced in a sputtering yield as simple carbon. Not only can it be reduced to about 1/2, but it can be removed from the vacuum chamber as carbon oxide or carbon oxide gas product. Further, carbon released from the target surface can be removed as carbon monoxide or carbon dioxide.

In the present invention, the substrate on which the film is formed is preferably made of plastic. Since the amount of heat incident on the substrate can be reduced by the direct current sputtering method as compared with the high frequency sputtering method, the effect of the present invention can be sufficiently obtained when using a plastic substrate that is more heat resistant than glass or metal. Examples of the plastic substrate include an acrylic resin, a polycarbonate resin, a polyolefin resin, and an epoxy resin. On the other hand, although a small amount of carbon is contained in the film formed by the reactive sputtering method, it is difficult to obtain 5% from the viewpoint of the refractive index and the transmittance.
There is no problem if the carbon concentration is not more than 3% by weight.

Here, the production of the sintered body of the present invention will be described with reference to FIG. First, raw materials for preparing a sintered body (for example, zinc sulfide and silicon dioxide are selected as substances having an insulating property, and carbon not containing a diamond structure is selected as a conductive material) are prepared. The average particle size of the insulating material is about 4 μm, and the average particle size of the conductive material is preferably 4 μm. After the insulating material and the conductive material are weighed, they are mixed and stirred at a fixed ratio. Subsequently, the mixture is contained in a container and molded under a pressure of 0.5 to 5 t / cm ² . This molded product is fired in a non-oxidizing atmosphere. The firing temperature is lower than the reaction temperature between the raw material components. If the firing is performed at a temperature equal to or higher than the reaction temperature of the raw material components, a conductive material may be scattered as a result, and a sintered body having reduced electric resistivity cannot be obtained. Next, after measuring the electrical resistivity, the relative density, and the like, only the sintered body having a good evaluation is selected. On the other hand, a metal base (packing plate) is prepared. The obtained sintered body is bonded to form a sintered body target.
The sintered target is placed on a cathode provided in a vacuum chamber of a DC sputter ring device. O _{2 in the} device
Gas and Ar gas are introduced and the gas pressure in the vacuum chamber is 4 to 9 ×
Set to 10 ^-1 Pa. O ₂ gas to Ar gas ratio (sc
cm) is suitably about O ₂ : Ar = 1: 99 to 10:90. By controlling the cathode voltage and current, an insulating thin film is formed on the substrate without causing abnormal discharge.

FIG. 2 is a diagram showing the flow of charges in the target of the sintered body according to the present invention. In the figure, a white portion indicates an insulating material, and a black portion indicates a conductive material. The substance having an insulating property and the material having a dielectric property are mixed on average, and the electric low efficiency as a whole is lower than the electric low efficiency of only the insulating substance. According to the present invention, a highly insulating material such as a dielectric, a phosphor, or a piezoelectric element can be formed at a high speed and at a low temperature, and the film quality variation in the formed film can be reduced.

[0033]

Next, the present invention will be described specifically with reference to examples. In the embodiment of the present invention, a means of sintering after press molding at room temperature was adopted. Other means other than this embodiment include HP (Hot Press) and HIP (Hot isostatic Press).
ing, high-temperature hydrostatic compression) and the like. Rather, HP
Since HIP and HIP simultaneously apply heat and pressure to sinter, they can be molded with a smaller pressure than when pressed at room temperature, and also have the advantage that a large sintered body can be obtained at once. .

EXAMPLE 1 Zinc sulfide having an average particle size of about 4 μm and a purity of 5N (99.999%) and silicon dioxide having an average particle size of about 4 μm and a purity of 4N (99.99%) were mixed at a molar ratio of 8: 2. After weighing, the powder mixed was mixed with graphite carbon powder having an average particle size of about 5 μm and a purity of 4N (99.99%) in a range of 2.5 to 40 vo1%, and then a ball mill (a table-top ball mill model V-IM manufactured by Irie Shosha) was mixed. After mixing and stirring for 1 hour, the diameter is 20 m at a pressure of 3 t / cm ^2.
m. The molded article was kept at 845 ° C. in nitrogen and fired for 2 hours. It was cooled to 150 ° C. and taken out, and the resistivity and the relative density were measured. Table 1 shows the results.

[0035]

[Table 1]

Comparative Example 1 When calcination was performed in the same manner as in Example 1 except that only the calcination temperature was changed from 845 ° C. to 1100 ° C., the molded product turned light gray without solidifying. Analysis of the remaining material showed no carbon and much less sulfur than the original. (Because carbon sulfide is formed at a temperature of 850 to 950 ° C. from carbon and sulfur, the temperature is higher than this temperature.
At 0 ° C., it is considered that a reaction between carbon and sulfur among the raw materials occurred, and the raw materials were scattered from the system as carbon sulfide. )

Example 2 A sintered body was produced in the same manner as in Example 1, except that only the molding pressure and the diameter of the mold were changed, and molding was performed at a pressure of 3 to 5 t / cm ^{2 to} a size of 5 inches. The insulator target containing the conductive material thus produced has a relative density of 66 to 7
The sintered body was 4% and the specific resistance was several Ωcm to 10 ⁻² Ωcm.

Comparative Example 2 When a ZnS / SiO ₂ target containing no conductive material was subjected to DC sputtering under the same conditions at a power of 500 W, an abnormal discharge called arcing occurred.
The film formation was stopped because a spark-like discharge was developed where the erosion area was originally formed. When the surface of the target was observed after breaking the vacuum and releasing to atmospheric pressure, the target was darkened.

Example 3 Example 2 was applied to a sputtering apparatus (model 8EP) manufactured by Tokuda Seisakusho.
After setting a ZnS / SiO ₂ target made of carbon having no diamond structure as a conductive material manufactured by the method described in the above method and evacuating the vacuum chamber up to the order of 10 ⁻⁵ Torr,
Ar gas was introduced into the vacuum chamber at a flow rate of 60 sccm (60 cc per minute). The gas pressure in the vacuum chamber after introducing 60 sccm of Ar gas was 5 × 10 ⁻³ Torr. Using this sintered body target as a cathode, ZnS / SiO ₂ was deposited by a direct current sputtering method at an input power of 500 W. The deposition rate was 1725 ° / min, and the substrate temperature was 1 minute and 10 seconds later (ZnS / Zn). / SiO ₂ film thickness of 2000 °). The polycarbonate substrate did not deform and satisfied the characteristics as an optical recording medium.

COMPARATIVE EXAMPLE 3 A ZnS / SiO ₂ target containing no conductive material was subjected to high-frequency sputtering with a traveling wave power of 500 W under the same conditions as in Example 3, and the film formation rate was 1078 °.
/ Min, and the substrate temperature at that time after 1 minute 51 seconds (Z
The temperature was 162 ° C. at a film thickness of nS / SiO ₂ of 2000 °). The substrate made of polycarbonate (polycarbonate had a thermal deformation temperature of 134 ° C.) was deformed due to the amount of incident heat and was distorted from the disk shape.

Example 4 Using a sputtering device (Model 8EP) manufactured by Tokuda Seisakusho Co., as a target, the carbon sintered body having no diamond structure obtained in Example 1 (with a carbon concentration of 15 to 40%) was used as a target. The film was set, and a film was formed by a direct current sputtering method with an input power of 500 W. The introduced gas at this time was Ar gas 57 sccm and O ₂ gas 3 sccm,
The gas pressure was 5 × 10 ⁻³ Torr. At an oxygen mixing ratio of 5%, the film forming rate of the carbon film alone was reduced to about 1/2 as compared with the case without oxygen mixing. No oxygen mixing (Ar gas 60 sccm) Carbon deposition rate = 204 ° / min Oxygen mixing ratio 5% (Ar gas 57 sccm, O ₂ gas 3 s)
ccm) Carbon film formation rate = 108 ° / min

Example 5 A ZnS / SiO ₂ sintered body containing carbon having no diamond structure according to the present invention (Example 1 (provided that the carbon concentration is 15 to 40%) was measured by a sputtering apparatus (Model 8EP) manufactured by Tokuda Seisakusho Co., Ltd. Was set as a target, and 500 W was obtained by DC sputtering.
With the input power of At this time, the introduced gas is Ar
60 sccm gas without oxygen mixing and Ar
The conditions were 57 sccm, O ₂ gas 3 sccm, oxygen mixture ratio 5%, and the gas pressure was 5 × 10 ⁻³ T for both conditions.
orr. Table 2 shows the results. Table 3 was prepared by converting the carbon concentration in the film from the film thickness value obtained in Example 4. In Table 3, RF is the high frequency sputtering method (Comparative Example), and DC is the DC sputtering method (Example of the present invention). At the carbon concentration level of 40% by volume or less according to the present invention, the carbon concentration in the film is 4% by weight or less.

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

According to the first aspect of the present invention, a high-frequency sputtering method must be used when forming a sputtered thin film, which is most often used when the target is an insulator.
By using a sintered body having conductivity, a DC sputtering method that is advantageous in terms of performance and running maintenance can also be used. According to the second aspect of the present invention, the recording film protective layer thin film for an optical disk conventionally formed by the high frequency sputtering method can be formed by the DC sputtering method. According to the third aspect of the present invention, it is possible to use the DC sputtering method without affecting the produced film. According to the fourth aspect of the present invention, by setting the temperature lower than the reaction temperature of each component, the sintered body can be made conductive without changing the main material (substance having an insulating property). According to the fifth aspect of the present invention, carbon acts at a relatively low temperature of about 500 ° C., but even when the firing temperature is 500 ° C. or more, the carbon is oxidized by treating in a non-oxidizing atmosphere. Processing can be performed without According to the invention of claim 6, since the film can be formed by the DC sputtering method, the film forming speed is improved, the amount of incident energy with respect to the substrate is reduced, the area can be increased, and the complexity of the sputtering power supply running is increased. Costs can be reduced.
According to the seventh aspect of the present invention, by introducing oxygen, carbon can be prevented from remaining on the substrate surface, and the content of carbon in the formed film can be reduced. According to the eighth aspect of the present invention, since the film can be formed by the DC sputtering method, the amount of incident energy on the substrate is reduced, so that the film can be formed on a plastic substrate without deformation due to heat. According to the invention of claim 9, carbon is slightly contained in the film,
As a result, the residual stress of the film is reduced, so that the recording sensitivity, C / N, erasing rate, and the like due to repetition of recording and erasing hardly deteriorate.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a sintered body manufacturing process of the present invention.

FIG. 2 is a schematic diagram showing a flow of electric charges in a target of a sintered body according to the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 7/26 531 C04B 35/00 T (72) Inventor Yasuchi Aman 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 Inside Ricoh Co., Ltd. (72) Inventor Yuji Miura 1-3-6 Nakamagome, Ota-ku, Tokyo F-term inside Ricoh Co., Ltd. 4G030 AA37 AA55 AA60 BA02 BA09 CA08 GA24 GA27 4K029 AA11 BA34 BA46 BA51 BC05 BD12 CA05 DC02 DC34 5D029 LA12 LA14 LA15 LB01 5D121 AA03 EE09 EE11

Claims (9)

[Claims] An insulative substance which is a main component and a conductive material of a conductive inorganic compound other than carbon or metal which do not have a diamond structure are mixed and fired, and the obtained material is obtained. A sintered body, wherein the electric resistivity of the sintered body is lower than the electric resistivity of the insulating material before sintering. 2. The sintered body according to claim 1, wherein the substance having an insulating property is a mixture of zinc sulfide and silicon dioxide, and the conductive material is carbon having no diamond structure. 3. The content of carbon, which does not include a diamond structure, which is a conductive material, in the entire sintered body is 40%.
The sintered body according to claim 2, wherein the content is not more than% by volume. 4. A process in which a substance having an insulating property as a main component and a material having a conductive inorganic compound other than carbon or metal having no diamond structure are mixed and fired. The method for producing a sintered body according to claim 1, wherein the sintering is performed at a temperature lower than a mutual reaction temperature of the substance having the conductivity and the material having the conductivity. 5. The method for producing a sintered body according to claim 4, wherein carbon having no diamond structure is used as the conductive material and firing is performed in a non-oxidizing atmosphere. 6. A sintered body according to claim 1, wherein said sintered body is a sintered body.
A film forming method, characterized in that a film is formed by a DC sputtering method using a sintered body target obtained by bonding any one of the sintered bodies obtained in the above to a metal substrate. 7. The film forming method according to claim 6, wherein DC sputtering is performed in an atmosphere of a reactive gas containing at least oxygen. 8. The method according to claim 6, wherein the substrate on which the film is formed is a plastic substrate. 9. The method according to claim 6, wherein the amount of carbon contained in the film formed on the substrate is 5% by weight or less.
A film formed by the film forming method according to 7 or 8.