TWI616425B - MgO-TiO sintered body target and manufacturing method thereof - Google Patents

Abstract

A MgO-TiO sintered body contains 25 to 90 mol% of TiO, and the remaining portion is composed of MgO and unavoidable impurities. The problem is to provide a high-density target and a method for manufacturing the same. The high-density target can be subjected to direct current (DC) sputtering with a high film formation speed and few particles.

Description

MgO-TiO sintered body target and manufacturing method thereof

The present invention relates to a magnesium oxide target and a method for manufacturing the same. The magnesium oxide target is used to form a magnesium oxide layer for a magnetic recording medium for a magnetic disk device or an electronic device such as a tunnel magnetoresistance (TMR) element. In particular, it relates to a conductive and high-density sintered body magnesium oxide target for sputtering and a method for producing the same.

In recent years, with the miniaturization and high recording density of magnetic disks, research and development of magnetic recording media have been carried out. In particular, various improvements have been made to magnetic layers or base layers. The hard disk recording density increases rapidly year by year, can be considered in the future from today's 600Gbit / in ² areal density of the reach 1Tbit / in ^2. If the recording density reaches 1 Tbit / in ² , the size of the recording bit will be less than 10 nm. In this case, it is expected that paramagnetization caused by thermal fluctuations will become a problem, and materials currently being used are expected, for example, for Co-Cr Adding Pt to the base alloy to improve the crystal magnetic anisotropy is not enough to solve the problem. The reason for this is that magnetic particles that exhibit stable ferromagnetism with a size of 10 nm or less must have higher crystalline magnetic anisotropy.

The reasons described above, with the phase FePt L1 ₀ structure as ultrahigh density recording media material attracted attention. The FePt phase having the L1 ₀ structure has high crystal magnetic anisotropy, and is excellent in corrosion resistance and oxidation resistance. Therefore, it is expected to be a material suitable for use as a magnetic recording medium. Furthermore, when the FePt phase is used as an ultra-high-density recording medium material, it is required to develop a technique in which regular FePt magnetic particles are dispersed in a magnetically isolated state at a high density and in a uniform direction as much as possible. In order to impart magnetic anisotropy to the FePt thin film, it is necessary to control the crystallization direction, which can be easily achieved by selecting a single crystal substrate. It has been reported that, for orienting the magnetization azimuth axis vertically, a magnesium oxide film is suitable as a base layer of the FePt layer.

Furthermore, it is also known that a magnesium oxide film or the like is also used as an insulating layer (tunnel barrier) of a TMR element used for a magnetic head (for a hard disk) or a MRAM. The magnesium oxide film described above was previously formed by a vacuum evaporation method, but recently, in order to facilitate the simplification of the manufacturing process or increase the area, a magnesium oxide film using a sputtering method has been produced. As a conventional technique, there are the following known documents.

The above Patent Document 1 discloses a magnesium oxide target composed of a magnesium oxide sintered body having a purity of 99.9% or more and a relative density of 99% or more, an average particle size of 60 μm or less, and an average particle size of 2 μm within the crystal grains. The following microstructures with radians of pores can cope with sputter filming speeds above 1000Å / min. The method is based on the following method: adding and mixing magnesium oxide fine powder having an average particle diameter of 100 nm or less to a high-purity magnesium oxide powder, and then forming the molded body by primary sintering and secondary sintering.

The above patent document 2 proposes a magnesium oxide target, which is composed of a magnesium oxide sintered body with a relative density of 99% or more, and can obtain 500 Å / min or more in a sputtering film formation in an Ar environment or an Ar-O ₂ mixed environment. The film formation speed is obtained by CIP forming a high-density magnesium oxide powder having an average particle diameter of 0.1 to 2 μm at a pressure of 3 t / cm ² or more, and sintering the obtained formed body.

In the aforementioned Patent Document 3, a magnesium oxide target is described, which is composed of a magnesium oxide sintered body having a purity of 99.9% or more and a relative density of 99.0% or more. The magnesium oxide target is capable of responding to a sputtering film formation speed of 600 Å / min or more. A target composed of magnesium oxide is described as follows: a high-purity magnesium oxide powder is added and mixed with fused magnesium oxide powder and magnesium oxide fine powder having an average particle diameter of 100 nm or less, and then the molded body is sintered once and Secondary sintering; sputter method can be used to produce films with good alignment, crystallinity, and film characteristics at higher film formation speeds. Magnesium oxide film.

The above-mentioned Patent Document 4 proposes a target containing MgO as a main component and a method for manufacturing the same, which are aimed at low discharge voltage, sputtering resistance during discharge, fast discharge response, and insulation, and are used for the protective film A _C dielectric layer of the PDP type, the particle La, Y particle, Sc particles are dispersed in the MgO as a main component of a target.

In the aforementioned Patent Document 5, a target mainly composed of MgO is proposed, which aims to improve the strength, fracture toughness value, and thermal shock resistance, and disperse LaB ₆ particles in the MgO matrix, and reduce the gas before sintering. Reduction treatment is performed in the environment, and primary sintering and secondary sintering are performed at a specific temperature.

The above-mentioned Patent Document 6 describes a target containing MgO as a main component, which specifies a relative density and an average crystal grain size of 0.5 to 100 μm, and uses rare earth elements such as Sc, Y, La, Ce, Gd, Yb Nd is dispersed in MgO matrix. In the aforementioned Patent Document 7, it is proposed to sinter MgO compacts by a discharge plasma sintering method for the purpose of producing a high-density sintered body.

In the above-mentioned Patent Documents 8 and 9, it is proposed that the final limiting density be set to 3.568 g / cm ³ in order to improve mechanical properties and thermal conductivity and reduce environmental pollution caused by gas generation, by uniaxial pressure Sintered to obtain MgO sintered body with many (111) planes; uniaxial pressure sintering of MgO raw material powder with a particle size of 1 μm or less, and then heat treatment in an oxygen environment at a temperature of 1273K or more. In this case, MgO is used as the raw material powder, and the method for increasing the density is limited by the sintering conditions.

The above-mentioned patent document 10 proposes a target for large-scale and uniform film formation of MgO film, and proposes that the average crystal grain size, density, bending resistance, and centerline average roughness of the target surface are specified, and the particle size of the raw material powder is set as 1 μm or less, followed by a granulation step, sintering at a specific load and temperature, and finishing the centerline average roughness Ra surface of the target to 1 μm or less. Furthermore, Patent Document 11 describes a perpendicular magnetic recording medium in which a non-magnetic substrate is used. A non-magnetic seed layer composed of any one of MgO, NiO, TiO or Ti carbides having a NaCl-type structure is formed with the non-magnetic base layer.

Patent Document 1: Japanese Patent Application Laid-Open No. 10-130827

Patent Document 2: Japanese Patent Application Laid-Open No. 10-130828

Patent Document 3: Japanese Patent Application Laid-Open No. 10-158826

Patent Document 4: Japanese Patent Application Laid-Open No. 10-237636

Patent Document 5: Japanese Patent Application Laid-Open No. 11-6058

Patent Document 6: Japanese Patent Application Laid-Open No. 11-335824

Patent Document 7: Japanese Patent Application Laid-Open No. 11-139862

Patent Document 8: Japanese Patent Application Laid-Open No. 2009-173502

Patent Document 9: International Publication No. 2009/096384

Patent Document 10: Japanese Patent Application Laid-Open No. 2000-169956

Patent Document 11: Japanese Patent Application Laid-Open No. 2004-213869

In recent years, the use of electronic devices such as magnetic recording media of magnetic disk devices (hard disks), tunneling magnetoresistance (TMR) elements, and the like has increased the demand for magnesium oxide films. Since this magnesium oxide is an insulating material, high frequency (RF) sputtering is generally used. However, this RF sputtering has the following problems: the film formation speed is slow, the productivity is poor, and particles are easily generated, which deteriorates the film quality. Therefore, an object of the present invention is to provide a high-density target capable of performing direct-current (DC) sputtering with high film formation speed and few particle generation, and a method for manufacturing the same.

In order to solve the above problems, the present inventors made intensive studies, and as a result, they obtained the following insight: MgO made of magnesium oxide is mixed with a NaCl-type crystal structure having the same structure and The target of a composite oxide of conductive titanium oxide TiO with a lattice constant having a similar value can obtain a conductive sintered body, which can be DC sputtered, and the obtained film has the same crystal structure as magnesium oxide, so it will not Impairs its function as a basement membrane.

Based on this knowledge, the present invention provides: 1) a MgO-TiO sintered body, which contains 25 to 90 mol% of TiO, and the remainder is composed of MgO and unavoidable impurities; 2) the sintering of MgO-TiO as described in 1) above Body, its relative density is 95% or more; 3) The MgO-TiO sintered body as described in 1) or 2) above has a bulk resistivity of 10Ω. cm or less; 4) The MgO-TiO sintered body according to any one of 1) to 3) above, wherein there are two types of phases, namely, a TiO phase and an MgO phase, and the longest diameter of the MgO phase is 50 μm or more, each 1 mm ² 5 or less; 5) A method for producing a MgO-TiO sintered body, which is a method for producing a sintered body for sputtering using MgO containing 25 mol% or more and 90 mol% or less of TiO, which is characterized in that the average particle size is 10 μm The following MgO powder is mixed with a raw material powder composed of TiO powder having an average particle diameter of 50 μm or less, and hot-pressed at a temperature of 1250 to 1450 ° C. and a pressure of 200 kgf / cm ² or more.

The present invention can provide a magnesium oxide-based sintered body with high density and low volume resistivity. When it is used as a target, the film can be formed by DC sputtering, so the film forming speed can be significantly increased, and stable sputtering can be achieved, so it has the excellent effect of generating a small amount of particles. In addition, since an expensive RF power source for RF sputtering is not required, it has an excellent effect that the cost of equipment can be reduced.

FIG. 1 is a tissue image obtained by observing the target of Example 2 using a laser microscope.

FIG. 2 is a tissue image obtained by observing the target of Example 2 using a laser microscope (an image obtained by reducing FIG. 1 by about 1/5).

A major feature of the MgO-TiO sintered body of the present invention is the addition of TiO to MgO. By adding conductive TiO, a conductive sintered body made of MgO-TiO can be obtained. Therefore, a sputtering target made of the sintered body can be used for DC sputtering, and the amount of particles generated during sputtering can be reduced. .

As described above, the present invention is capable of performing DC sputtering by adding conductivity to the sintered body by adding conductive TiO, and the more important aspect is that the TiO has the same NaCl type crystal structure as MgO, and It has a lattice constant similar to that of MgO. It is the same oxide as MgO and will not react with MgO to form an intermediate compound. Therefore, the film formed by sputtering has an excellent effect of not impairing its characteristics compared with the conventional film of magnesium oxide alone.

Examples of the conductive material applicable to the present invention include TiN, TiC, CrN, NbN, NbC, TaN, TaC, ZrN, ZrC, VN, VC, and the like in addition to TiO. From the standpoint of lattice constant, TiC, VC, WC, and TiN are desired. However, it is considered that these carbides or nitrides contain a large amount of oxygen impurities in the raw material powder, so it is possible to mix and sinter with MgO It will decompose, or reduce the oxygen of MgO, or form intermediate compounds with MgO, which will impair the original characteristics (lattice constants, etc.) of Mg or "TiC, VC, WC, TiN".

In the MgO-TiO sintered body of the present invention, the content of TiO is set to 25 mol% or more and 90 mol% or less, preferably 35 mol% or more and 70 mol% or less. If it is less than 25 mol%, it is difficult to obtain a volume resistance capable of performing DC sputtering. On the other hand, if it exceeds 90 mol%, the formed film has characteristics close to that of pure TiO, and the desired characteristics cannot be obtained, which is not satisfactory.

In addition, in the present invention, as long as DC sputtering can be performed without significantly changing the characteristics of the film, The scope also includes the case of adding other materials.

The MgO-TiO sintered body of the present invention preferably has a relative density of 95% or more. Furthermore, the relative density is preferably 98% or more. When such a high-density sintered body is used as a sputtering target, the amount of particles generated during sputtering can be reduced.

Also, regarding the MgO-TiO sintered body of the present invention, the volume resistivity is preferably 10Ω. cm or less. Furthermore, it is preferably 0.01Ω. cm or less. When a sintered body having such a low volume resistance value is used as a sputtering target, more stable DC sputtering can be performed. Thereby, compared with the conventional RF sputtering, since the film-forming speed can be accelerated, productivity can be improved.

In addition, it should be understood that even if it exceeds the range of the volume resistivity, as long as DC sputtering can be performed, it is included in the present invention.

Moreover, it is preferable that the MgO-TiO sintered body of the present invention has two types of phases, namely, a TiO phase and an MgO phase, and the longest diameter of the MgO phase is 50 μm or more, and 10 or less per 1 mm ² . Further, it is preferable that the longest diameter of the MgO phase is 30 μm or more, and 25 or less per 1 mm ² . The TiO phase is desirably connected in a network and dispersed.

The present invention is a sintered body in which MgO and TiO coexist with greatly different electrical conductivity. However, if a coarse MgO phase is present, abnormal discharge with the starting point easily occurs. By reducing the area of such coarse MgO phase as much as possible, abnormal discharge starting from the coarse MgO phase can be suppressed, and the amount of particles can be reduced. In addition, the longest diameter of the MgO phase refers to the maximum length of the particles of the MgO phase formed on the polished surface of the sample taken from a part of the target.

The MgO-TiO sintered body of the present invention can be produced by the following method.

First, MgO powder and TiO powder were prepared as raw materials. The MgO powder is preferably one having an average particle diameter of 10 μm or less, and the TiO powder is preferably one having an average particle diameter of 50 μm or less. If the particle diameter of the powder exceeds this range, it is difficult to achieve uniform mixing, and segregation and coarsening of crystals occur, which is not preferable. The particle diameter of the raw material powder is preferably fine, but it is difficult to miniaturize TiO. From the viewpoint of production, the average particle diameter is preferably 1 μm or more.

Next, these raw material powders are weighed so as to have a specific molar ratio, and they are simultaneously pulverized and mixed using a known method such as a ball mill.

The mixed powder obtained in this way is shaped and sintered in a vacuum environment or an inert gas environment by a hot pressing method. In addition to the above hot pressing, various pressure sintering methods such as plasma discharge sintering can be used. In particular, the hydrostatic and hydrostatic sintering method is effective for increasing the density of a sintered body. The holding temperature during sintering is preferably set to a temperature range of 1250 to 1450 ° C. The holding pressure during sintering is preferably set to a pressure range of 200 kgf / cm ² or more.

Further, in the present invention, a sputtering target can be produced by processing the sintered body obtained in this way into a desired shape by grinding or the like. The sputtering target produced in this way can be subjected to DC sputtering, so the film forming speed is significantly increased, and productivity can be greatly improved. Furthermore, since the amount of particles generated during sputtering can be reduced, there is an excellent effect that the yield during film formation can be improved.

[Example]

Hereinafter, it demonstrates based on an Example and a comparative example. Furthermore, this embodiment is only an example, and is not limited in any way by this example. That is, the present invention is limited only by the scope of the patent application, and includes various modifications other than the embodiments included in the present invention.

(Example 1)

MgO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), and TiO powder having an average particle diameter of 30 μm and a purity of 3N (99.9%) were prepared as raw material powders. Then, these raw material powders were prepared so as to have the composition ratios described in Table 1.

Next, the powder to be weighed and the zirconia ball of the crushing medium are sealed together in a Ar mill with a capacity of 10 liters in a ball mill pot, and the two powders are rotated uniformly to disperse the powder 20 Mix and pulverize for more than one hour.

Next, the powder taken out of the container was filled into a graphite mold with a diameter of 180 mm, and it was shaped and sintered using a hot pressing device. The conditions of the hot pressing are as follows: set to a vacuum environment, keep the temperature at 1400 ° C, and pressurize at 250 kgf / cm ² from the start of the temperature increase until the end of the hold.

The sintered body produced in this way was subjected to a density measurement using the Archimedes method, and as a result, it had a relative density of 98%. Here, the relative density is a value obtained by dividing a measured density of a target by a calculated density (also referred to as a theoretical density). The calculated density is the density when it is assumed that the constituent components of the target are mixed in an interdiffusion or unreacted manner. Formula: Calculated density = Σ (molecular weight of constituent components × mole ratio of constituent components) / Σ (molecular weight of constituent components × composition The molar ratio of the ingredients / theoretical density of the constituents), and the theoretical density of MgO is 3.585 g / cm ³ , and the theoretical density of TiO is 4.93 g / cm ³ . The same applies to the following examples and comparative examples.

The volume resistance measurement of the sintered body by the four-terminal method was found to be 0.01Ω. cm. The cross section of the sintered body was ground, and the center portion was observed with a laser microscope. As a result, two types of phases, MgO phase and TiO phase, were observed. The longest diameter of the MgO phase was 50 μm or more and 30 μm or more. Pcs / mm ² , 15 pcs / mm ² .

Furthermore, the sintered body was ground into a target shape by a grinding machine to produce a disk-shaped target. This was mounted on a DC sputtering apparatus to perform sputtering. The sputtering conditions were set to sputtering power: 0.5 kW, Ar gas pressure: 5 Pa, and a film was formed on a silicon substrate for 30 seconds. Then, the number of particles attached to the substrate was measured using a particle counter. The number of particles at this time was 120.

(Example 2)

MgO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), and TiO powder having an average particle diameter of 20 μm and a purity of 3N (99.9%) were prepared as raw material powders. Then, these raw material powders were prepared so as to have the composition ratios described in Table 1.

Next, the weighed powder and the zirconia grinding ball of the pulverizing medium are sealed in a ball mill container with a capacity of 10 liters in an Ar environment, and the two powders are rotated and dispersed uniformly for more than 20 hours to mix and pulverize.

Next, the powder taken out of the container was filled into a graphite mold with a diameter of 180 mm, and it was shaped and sintered using a hot pressing device. The conditions of the hot pressing are as follows: set the vacuum environment, keep the temperature at 1400 ° C, and pressurize at 300 kgf / cm ² from the start of the temperature rise until the end of the hold.

The density measurement by the Archimedes method was performed on the sintered body produced in this manner, and the relative density was 98%. The volume resistance measurement of the sintered body by the four-terminal method was 0.003Ω. cm. The cross section of the sintered body was ground, and the center portion was observed with a laser microscope. The results are shown in Fig. 1. As shown in FIG. 1, two types of phases, an MgO phase (dark gray portion) and a TiO phase (light gray portion), were observed. In addition, the longest diameter of the MgO phase is 50 μm or more and 30 μm or more. As shown in FIG. 2, there are one and two, respectively. When the image area is converted into an area per 1 mm ² , it is 3 / mm ² , 5 pieces / mm ² . Furthermore, in other examples and comparative examples (except for Comparative Example 1), it was confirmed in the structure image of the same magnification as in FIG. 1 that the MgO phase and the TiO phase were formed in two phases. In the magnified image area, the number of MgO phases with a maximum diameter of 50 μm or more and 30 μm or more is counted and converted into an area per 1 mm ² to be the number per unit area.

Furthermore, the sintered body was ground into a target shape by a grinding machine to obtain a disk-shaped target. This was mounted on a DC sputtering apparatus to perform sputtering. The sputtering conditions were set to sputtering power: 0.5 kW, Ar gas pressure: 5 Pa, and a film was formed on a silicon substrate for 30 seconds. Then, the number of particles attached to the substrate was measured using a particle counter. The number of particles at this time was 51.

(Example 3)

MgO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), and TiO powder having an average particle diameter of 30 μm and a purity of 3N (99.9%) were prepared as raw material powders. Then, these raw material powders were prepared so as to have the composition ratios described in Table 1.

Next, the weighed powder and the zirconia grinding ball of the pulverizing medium are sealed in a ball mill container with a capacity of 10 liters in an Ar environment, and the two powders are rotated and dispersed uniformly for more than 20 hours to mix and pulverize.

Next, the powder taken out of the container was filled into a graphite mold with a diameter of 180 mm, and it was shaped and sintered using a hot pressing device. The conditions of the hot pressing are as follows: set to a vacuum environment, keep the temperature at 1400 ° C, and pressurize at 250 kgf / cm ² from the start of the temperature increase until the end of the hold.

The sintered body produced in this manner was subjected to a density measurement by the Archimedes method, and as a result, had a relative density of 99.5%. The volume resistance measurement of the sintered body by the four-terminal method was 0.002Ω. cm. In addition, the cross section of the sintered body was ground, and the center portion was observed with a laser microscope. As a result, two types of MgO phase and TiO phase were observed. The longest diameter of the MgO phase was 50 μm or more and 30 μm or more. Pcs / mm ² , 5 pcs / mm ² .

Furthermore, the sintered body was ground into a target shape by a grinding machine to produce a disk-shaped target. This was mounted on a DC sputtering apparatus to perform sputtering. The sputtering conditions were set to sputtering power: 0.5 kW, Ar gas pressure: 5 Pa, and a film was formed on a silicon substrate for 30 seconds. Then, the number of particles attached to the substrate was measured using a particle counter. The number of particles at this time was 46.

(Example 4)

MgO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), and TiO powder having an average particle diameter of 30 μm and a purity of 3N (99.9%) were prepared as raw material powders. Then, these raw material powders were prepared so as to have the composition ratios described in Table 1.

Next, the weighed powder and the zirconium dioxide grinding ball of the crushing medium are sealed in a ball mill container with a capacity of 10 liters in an Ar environment, and the two powders are rotated uniformly for 10 hours to Mix on top and crush.

Next, the powder taken out of the container was filled into a graphite mold with a diameter of 180 mm, and it was shaped and sintered using a hot pressing device. The conditions of the hot pressing are as follows: set to a vacuum environment, keep the temperature at 1400 ° C, and pressurize at 250 kgf / cm ² from the start of the temperature increase until the end of the hold.

The sintered body produced in this manner was subjected to a density measurement by the Archimedes method, and as a result, had a relative density of 99.5%. The volume resistance measurement of the sintered body by the four-terminal method was 0.0005Ω. cm. In addition, the cross section of the sintered body was ground, and the center portion was observed with a laser microscope. As a result, two types of phases, MgO phase and TiO phase, were observed. The longest diameter of the MgO phase was 50 μm or more and 30 μm or more. Pcs / mm ² , 0 pcs / mm ² .

Furthermore, the sintered body was ground into a target shape by a grinding machine to obtain a disk-shaped target. This was mounted on a DC sputtering apparatus to perform sputtering. The sputtering conditions were set to sputtering power: 0.5 kW, Ar gas pressure: 5 Pa, and a film was formed on a silicon substrate for 30 seconds. Then, the number of particles attached to the substrate was measured using a particle counter. The number of particles at this time was 22 particles.

(Comparative example 1)

Only MgO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%) was prepared as a raw material powder. Then, the powder was sealed in a ball mill container with a capacity of 10 liters together with a zirconia grinding ball of a pulverizing medium, and the powder was pulverized by rotating it for 10 hours.

Next, the powder taken out of the container was filled into a graphite mold with a diameter of 180 mm, and it was shaped and sintered using a hot pressing device. The conditions of the hot pressing are as follows: set to a vacuum environment, keep the temperature at 1500 ° C, and pressurize at 300 kgf / cm ² from the beginning of the temperature rise until the end of the hold.

The sintered body produced in this way was subjected to density measurement by the Archimedes method, and as a result, it had a relative density of 99%. Moreover, the volume resistance measurement of the sintered body was performed by the four-terminal method, but the resistance value was too high to measure.

This sintered body was cut into a target shape by a lathe to produce a disk-shaped target. Although it was sputtered by mounting it in a DC sputtering apparatus, it was not able to perform DC sputtering.

(Comparative example 2)

MgO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), and TiO powder having an average particle diameter of 25 μm and a purity of 3N (99.9%) were prepared as raw material powders. Then, these raw material powders were prepared so as to have the composition ratios described in Table 1.

Next, the weighed powder and the zirconium dioxide grinding ball of the pulverizing medium are sealed in a ball mill container with a capacity of 10 liters in an Ar environment, and the two powders are rotated and dispersed uniformly for more than 20 hours to mix and pulverize.

Next, the powder taken out of the container was filled into a graphite mold with a diameter of 180 mm, and it was shaped and sintered using a hot pressing device. The conditions of the hot pressing are as follows: set the vacuum environment, keep the temperature at 1400 ° C, and pressurize at 300 kgf / cm ² from the start of the temperature rise until the end of the hold.

The sintered body produced in this way was subjected to a density measurement by the Archimedes method, and as a result, it had a relative density of 96%. In addition, the volume resistance measurement of the sintered body was performed by the four-terminal method. As a result, the resistance value was high and the measurement was impossible. In addition, the cross section of the sintered body was ground, and the center portion was observed with a laser microscope. As a result, two types of phases, MgO phase and TiO phase, were observed. The longest diameter of the MgO phase was 50 μm or more and 30 μm or more. Pcs / mm ² , 35 pcs / mm ² .

The sintered body was ground into a target shape by a grinding machine to form a disk-shaped target. Although it was sputtered by mounting it in a DC sputtering apparatus, it was not able to perform DC sputtering.

(Comparative example 3)

MgO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), and TiO powder having an average particle diameter of 100 μm and a purity of 3N (99.9%) were prepared as raw material powders. Then, these raw material powders were prepared so as to have the composition ratios described in Table 1.

Next, the weighed powder and the zirconium dioxide grinding ball of the pulverizing medium are enclosed in a ball mill container with a capacity of 10 liters in an Ar environment, and the two powders are rotated and dispersed for more than 5 hours to mix and pulverize.

Next, the powder taken out of the container was filled into a graphite mold with a diameter of 180 mm, and it was shaped and sintered using a hot pressing device. The conditions of the hot pressing are as follows: set the vacuum environment, keep the temperature at 1400 ° C, and pressurize at 300 kgf / cm ² from the start of the temperature rise until the end of the hold.

The sintered body produced in this way was subjected to density measurement by the Archimedes method, and as a result, it had a relative density of 97%. The volume resistance measurement of the sintered body by the four-terminal method was 0.007Ω. cm. In addition, the cross section of the sintered body was ground, and the center portion was observed with a laser microscope. As a result, two types of phases, MgO phase and TiO phase, were observed. The longest diameters of the MgO phase were 50 μm or more and 30 μm or more. Pcs / mm ² , 53 pcs / mm ² .

Furthermore, the sintered body was ground into a target shape by a grinding machine to obtain a disk-shaped target. This was mounted on a DC sputtering apparatus to perform sputtering. The sputtering conditions were set to sputtering power: 0.5 kW, Ar gas pressure: 5 Pa, and a film was formed on a silicon substrate for 30 seconds. Then, the number of particles attached to the substrate was measured using a particle counter. The number of particles at this time was 2,000.

(Comparative Example 4)

MgO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), and TiO powder having an average particle diameter of 100 μm and a purity of 3N (99.9%) were prepared as raw material powders. Then, these raw material powders were prepared so as to have the composition ratios described in Table 1.

Next, the weighed powder and the zirconium dioxide grinding ball of the pulverizing medium are enclosed in a ball mill container with a capacity of 10 liters in an Ar environment, and the two powders are rotated and dispersed for more than 5 hours to mix and pulverize.

Next, the powder taken out of the container was filled into a graphite mold with a diameter of 180 mm, and it was shaped and sintered using a hot pressing device. The conditions of the hot pressing are as follows: set the vacuum environment, keep the temperature at 1400 ° C, and pressurize at 300 kgf / cm ² from the start of the temperature rise until the end of the hold.

The sintered body produced in this manner was subjected to a density measurement by the Archimedes method, and as a result, had a relative density of 99.5%. The volume resistance measurement of the sintered body by the four-terminal method was 0.002Ω. cm. In addition, the cross section of the sintered body was ground and observed with a laser microscope. As a result, two types of phases, MgO phase and TiO phase, were observed. The longest diameter of the MgO phase was 50 μm or more and 30 μm or more, 15 / mm. ² , 41 / mm ² .

Furthermore, the sintered body was ground into a target shape by a grinding machine to obtain a disk-shaped target. This was mounted on a DC sputtering apparatus to perform sputtering. The sputtering conditions were set to sputtering power: 0.5 kW, Ar gas pressure: 5 Pa, and a film was formed on a silicon substrate for 30 seconds. Then, the number of particles attached to the substrate was measured using a particle counter. The number of particles at this time was 500.

[Industrial availability]

The MgO-TiO sintered body of the present invention can be DC sputtered, so that compared with the case of RF sputtered conventional MgO sintered body, the film formation speed can be significantly increased, and a large effect of improving productivity can be obtained. In addition, DC sputtering can be realized by using an inexpensive DC power supply, so existing equipment can be directly used, and the cost of equipment investment can be reduced.

In view of the foregoing, the MgO-TiO sintered body of the present invention is useful as a magnesium oxide-based sputtering target used for forming a thin film for an electronic device such as a magnetic recording medium for a magnetic disk device or a tunneling magnetoresistance effect (TMR) element. In addition, it can be used in new fields such as antistatic or heat-resistant members as a conductive ceramic material that conventional insulating MgO cannot achieve.

Claims (4)

A sintered MgO-TiO sintered body containing 25 to 90 mol% of TiO, and the remaining portion is composed of MgO and unavoidable impurities. In addition, there are two types of phases, the TiO phase and the MgO phase, and the longest diameter of the MgO phase is a region of 50 μm or more , 10 per 1 mm ² or less. For example, the MgO-TiO sintered body in the first patent application scope has a relative density of 95% or more. For example, the bulk resistivity of the MgO-TiO sintered body in the first or second scope of the patent application is 10Ω. cm or less. A method for manufacturing a MgO-TiO sintered body is a method for manufacturing a MgO-TiO sintered body according to any one of claims 1 to 3, and is a sputtering method in which MgO contains 25 mol% or more and 90 mol% or less of TiO. A method for producing a sintered body for plating, characterized in that: a raw material powder composed of MgO powder having an average particle diameter of 10 μm or less and TiO powder having an average particle diameter of 50 μm or less is mixed at a temperature of 1250 to 1450 ° C. and 200 kgf / cm ^It is produced by hot-pressing at a pressure of ² or more.