WO2014156497A1

WO2014156497A1 - Mgo-tio sintered compact target and method for producing same

Info

Publication number: WO2014156497A1
Application number: PCT/JP2014/055346
Authority: WO
Inventors: 英生高見; 中村　祐一郎; 荒川　篤俊; 真一荻野
Original assignee: Jx日鉱日石金属株式会社
Priority date: 2013-03-29
Filing date: 2014-03-04
Publication date: 2014-10-02
Also published as: JPWO2014156497A1; SG11201501372QA; TWI616425B; TW201500323A; CN104661983A; CN111792919A; MY169936A; JP5925907B2

Abstract

A MgO-TiO sintered compact comprising 25 to 90 mol% of TiO, with the remainder made up by MgO and unavoidable impurities. The present invention addresses the problem of providing: a highly dense target which has a high film deposition speed and can be subjected to direct-current (DC) sputtering by which particles are formed in a reduced amount; and a method for producing the target.

Description

MgO-TiO sintered compact target and method for producing the same

The present invention relates to a magnesium oxide target used for forming a magnesium oxide layer for an electronic device such as a magnetic recording medium for a magnetic disk device or a tunnel magnetoresistive effect (TMR) element, and a method for manufacturing the same. The present invention relates to a high-density sintered high density 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 conducted, and various improvements have been made to the magnetic layer and the underlayer. The recording density of hard disks is rapidly increasing year by year, and it is considered that the future will reach 1 Tbit / in ² from the current surface density of 600 Gbit / in ² . When the recording density reaches 1 Tbit / in ² , the size of the recording bit becomes 10 nm or less. In that case, paramagnetization due to thermal fluctuation is expected to become a problem, and materials currently used, for example, Co— It is expected that a material in which crystal magnetic anisotropy is increased by adding Pt to a Cr-based alloy is not sufficient. This is because magnetic particles which stably behave as ferromagnetism with a size of 10 nm or less need to have higher crystal magnetic anisotropy.

For the reasons described above, FePt phase having an L1 ₀ structure is attracting attention as ultra-high density recording media material. FePt phase having an L1 ₀ structure with a high magnetocrystalline anisotropy, corrosion resistance and excellent oxidation resistance, is what is expected as a material suitable for the application as a magnetic recording medium. When the FePt phase is used as an ultra-high density recording medium material, it is required to develop a technique for aligning and dispersing the ordered FePt magnetic particles in as high a density as possible in a magnetically isolated state. It has been. In order to impart magnetic anisotropy to the FePt thin film, it is necessary to control the crystal direction. This can be easily achieved by selecting a single crystal substrate. It has been reported that a magnesium oxide film is suitable as an underlayer for the FePt layer in order to orient the magnetization azimuth axis perpendicularly.

Further, it is also known to be used for a magnetic head (for hard disk), a magnesium oxide film used as an insulating layer (tunnel barrier) of a TMR element used for MRAM, and the like. The magnesium oxide film as described above was formed by the vacuum evaporation method in the past, but recently, in order to simplify the manufacturing process and facilitate the enlargement of the area, the production of the magnesium oxide film using the sputtering method is performed. Has been done. As the prior art, there are the following known documents.

Patent Document 1 is magnesium oxide made of a magnesium oxide sintered body having a magnesium oxide purity of 99.9% or more and a relative density of 99% or more, having an average particle size of 60 μm or less and an average particle size of 2 μm in the crystal grains. Disclosed is a magnesium oxide target having a microstructure in which the following rounded pores are present and capable of handling a sputter deposition rate of 1000 Å / min or more. This is based on a method in which a magnesium oxide fine powder having an average particle size of 100 nm or less is added to and mixed with high-purity magnesium oxide powder, and the compact is subjected to primary sintering and secondary sintering.

Patent Document 2 is composed of a magnesium oxide sintered body having a relative density of 99% or more, and a film formation speed of 500 Å / min or more can be obtained in sputter film formation in an Ar atmosphere or an Ar—O ₂ mixed atmosphere. Proposed that CIP molding of high-density magnesium oxide powder having an average particle size of 0.1 to 2 μm at a pressure of 3 t / cm ² or more and sintering the resulting molded body. .

Patent Document 3 discloses a magnesium oxide target made of a magnesium oxide sintered body having a magnesium oxide purity of 99.9% or more and a relative density of 99.0% or more, and can cope with a sputter deposition rate of 600 Å / min or more. A target composed of magnesium oxide is described, and a high-purity magnesium oxide powder is mixed with an electrofused magnesium oxide powder and a magnesium oxide fine powder having an average particle size of 100 nm or less and molded, and the compact is subjected to primary sintering and secondary sintering. It is described that a magnesium oxide film having good orientation, crystallinity, and film characteristics can be formed at a high film formation rate by a sputtering method.

The Patent Document 4, a target and a manufacturing method thereof mainly containing MgO, discharge voltage is low, the sputtering resistance during discharge, the response of the fast discharge, the prospect of insulating, A _C-type PDP In order to use this as a protective film for the dielectric layer, it has been proposed to disperse La particles, Y particles, and Sc particles in a target mainly composed of MgO.

In Patent Document 5, LaB ₆ particles are dispersed in an MgO matrix and reduced before sintering with the aim of improving strength, fracture toughness value, and thermal shock resistance in a target mainly composed of MgO. Reduction treatment in a gas atmosphere, primary sintering at a predetermined temperature, and secondary sintering have been proposed.

In the above-mentioned Patent Document 6, in a target mainly composed of MgO, the relative density and the average crystal grain size are regulated to 0.5 to 100 μm, and the rare earth elements Sc, Y, La, Ce, It describes that Gd, Yb, and Nd are dispersed. Patent Document 7 proposes to sinter MgO green compacts by a discharge plasma sintering method with the aim of producing a high-density sintered body.

In Patent Document 8 and Patent Document 9, the final achieved density is 3.568 g / cm ³ , the mechanical properties and thermal conductivity are good, and the aim is to reduce atmospheric contamination due to gas generation. An MgO sintered body having a large number of (111) planes is obtained by pressure sintering. A MgO raw material powder having a particle size of 1 μm or less is uniaxially pressed and then heated to a temperature of 1273 K or higher in an oxygen atmosphere. It has been proposed to heat-treat. In this case, MgO is used as the raw material powder, and the technique for improving the density is limited to the sintering conditions.

Patent Document 10 proposes a target for uniformly forming a MgO film on a large scale, and defines an average crystal grain size, a density, a bending strength, and a central average roughness of a target surface. It has been proposed that the particle size of the raw material powder be 1 μm or less, then undergo a granulation step, sintering at a predetermined load and temperature, and surface finishing the target centerline average roughness Ra to 1 μm or less. In Patent Document 11, in a perpendicular magnetic recording medium, a non-magnetic material made of any one of MgO, NiO, TiO, or Ti carbide having a NaCl type structure is provided between a nonmagnetic substrate and a nonmagnetic underlayer. The formation of a magnetic seed layer is described.

Japanese Patent Laid-Open No. 10-130827 Japanese Patent Laid-Open No. 10-130828 Japanese Patent Laid-Open No. 10-158826 Japanese Patent Laid-Open No. 10-237636 Japanese Patent Laid-Open No. 11-6058 Japanese Patent Laid-Open No. 11-335824 JP-A-11-139862 JP 2009-173502 A International Publication No. 2009/096384 Pamphlet JP 2000-169956 A JP 2004-213869 A

In recent years, the demand for a magnesium oxide film is increasing by using an electronic device such as a magnetic recording medium of a magnetic disk device (hard disk) or a tunnel magnetoresistive effect (TMR) element. Since this magnesium oxide is an insulating material, radio frequency (RF) sputtering is usually used. However, this RF sputtering has a problem that the productivity is poor because the film forming speed is slow, and the quality of the film is deteriorated because particles are easily generated. In view of the above, an object of the present invention is to provide a high-density target capable of direct current (DC) sputtering with a high deposition rate and less particle generation, and a method for manufacturing the same.

In order to solve the above-mentioned problems, the present inventors have conducted intensive research. As a result, magnesium oxide MgO has the same NaCl-type crystal structure and has a close lattice constant. By using a composite oxide target in which TiO is mixed, a conductive sintered body can be obtained, and DC sputtering can be performed, and the obtained film has a crystal structure equivalent to that of magnesium oxide. The knowledge that the function as a base film etc. is not impaired was acquired.

Based on such knowledge, the present invention
1) MgO—TiO sintered body containing 25 to 90 mol% of TiO, the balance being MgO and inevitable impurities,
2) The MgO—TiO sintered body according to 1) above, wherein the relative density is 95% or more,
3) The MgO—TiO sintered body according to 1) or 2), wherein the bulk resistivity is 10 Ω · cm or less,
4) Any one of the above 1) to 3), wherein there are two phases of TiO phase and MgO phase, and the maximum diameter of the MgO phase is 10 μm or less per 1 mm ^2. MgO—TiO sintered body described in 1.
5) A method for producing a sintered compact for sputtering containing 25 mol% or more and 90 mol% or less of TiO in MgO, and a raw material comprising 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 There is provided a method for producing an MgO—TiO sintered body characterized by mixing powder and hot pressing the powder 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 sintered body having a high density and a low bulk resistivity. When this is used as a target, it is possible to form a film by DC sputtering, so that the film formation speed can be remarkably improved, and moreover stable sputtering is possible, so that the generation amount of particles is small. Has an excellent effect. In addition, since an expensive RF power source for RF sputtering is not required, there is an excellent effect that the cost of equipment can be reduced.

It is the structure | tissue image which observed the target of Example 2 with the laser microscope. It is the structure | tissue image (image which reduced FIG. 1 about 1/5 scale) which observed the target of Example 2 with the laser microscope.

One of the major features of the MgO—TiO sintered body of the present invention is that TiO is added to MgO. By adding TiO having conductivity, a conductive sintered body made of MgO—TiO can be obtained. Therefore, a sputtering target produced using this sintered body can be subjected to DC sputtering, and sputtering can be performed. The amount of particles that occur can be reduced.

In the present invention, as shown above, by adding TiO having conductivity, the sintered body is imparted with conductivity, and DC sputtering can be performed. It has the same NaCl-type crystal structure as MgO, has a lattice constant close to that of MgO, and does not react with MgO with the same oxide as MgO to produce an intermediate compound. Thereby, the film formed by sputtering has an excellent effect that the characteristics thereof are not impaired as compared with the conventional film of magnesium oxide alone.
In addition to TiO, examples of the conductive material applicable to the present invention include TiN, TiC, CrN, NbN, NbC, TaN, TaC, ZrN, ZrC, VN, and VC. From the viewpoint of lattice constant alone, TiC, VC, WC, and TiN are promising, but these carbides or nitrides contain a large amount of oxygen impurities in the raw material powder and decompose when mixed and sintered with MgO. Or may reduce the oxygen of MgO or generate an intermediate compound with MgO, and the characteristics (lattice constant, etc.) inherent in Mg and “TiC, VC, WC, TiN” may be impaired. Conceivable.

In the MgO—TiO sintered body of the present invention, the content of TiO is 25 mol% to 90 mol%, preferably 35 mol% to 70 mol%. If it is less than 25 mol%, it is difficult to obtain a bulk resistance capable of DC sputtering. On the other hand, if it exceeds 90 mol%, the properties of the formed film are close to those of pure TiO, and the desired properties cannot be obtained. .
The present invention includes cases where other materials are added as long as DC sputtering is possible and the characteristics of the film are not significantly changed.

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

In the MgO—TiO sintered body of the present invention, the bulk resistivity is preferably 10 Ω · cm or less. More preferably, it is 0.01 Ω · cm or less. Thus, when a sintered body having a low bulk resistance value is used as a sputtering target, more stable DC sputtering is possible. Thereby, since the film-forming speed can be increased as compared with the conventional RF sputtering, productivity can be improved.
In addition, even if it is the range exceeding said bulk resistivity, if DC sputtering is possible, it should be understood that it is included by this invention.

In the MgO—TiO sintered body of the present invention, it is preferable that the TiO phase and the MgO phase have two phases, and the region where the longest diameter of the MgO phase is 50 μm or more is 10 or less per 1 mm ² . More preferably, the number of the regions where the longest diameter of the MgO phase is 30 μm or more is 25 or less per 1 mm ² . The TiO phase is desirably dispersed in a network.

The present invention is a sintered body in which MgO and TiO having greatly different electrical conductivities coexist. However, if a coarse MgO phase is present, abnormal discharge starting from the sintered body tends to occur. By reducing the area of such a 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. The longest diameter of the MgO phase means the maximum length of particles forming the MgO phase on the polished surface of a sample collected 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 are prepared as raw materials. It is preferable to use 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. If the particle size of the powder exceeds this range, uniform mixing becomes difficult, and segregation and coarsening of crystals occur, which is not preferable. The particle size of the raw material powder is preferably finer, but TiO is difficult to be miniaturized, and the average particle size is preferably 1 μm or more from the viewpoint of production.
Next, these raw material powders are weighed so as to have a predetermined molar ratio, and are mixed by pulverization using a known method such as a ball mill.

The mixed powder thus obtained is molded and sintered by a hot press method in a vacuum atmosphere or an inert gas atmosphere. In addition to the hot press, various pressure sintering methods such as a plasma discharge sintering method can be used. In particular, the hot isostatic pressing is effective for improving the density of the sintered body. The holding temperature during sintering is preferably in the 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.

In the present invention, a sputtering target can be produced by processing the sintered body thus obtained into a desired shape by grinding or the like. Since the sputtering target manufactured in this manner can be DC-sputtered, the film formation rate is remarkably improved, and the productivity can be greatly improved. Furthermore, since the amount of particles generated during sputtering can be reduced, the yield can be improved during film formation.

Hereinafter, description will be made based on examples and comparative examples. In addition, a present Example is an example to the last, and is not restrict | limited at all by this example. In other words, the present invention is limited only by the scope of the claims, and includes various modifications other than the examples included in the present invention.

(Example 1)
As raw material powder, TiO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), an average particle diameter of 30 μm, and a purity of 3N (99.9%) was prepared. And these raw material powders were prepared so that it might become the composition ratio described in Table 1.
Next, the weighed powder was enclosed in a 10-liter ball mill pot together with zirconia balls as a grinding medium in an Ar atmosphere, and rotated and mixed and ground for 20 hours or more so that both powders were uniformly dispersed.
Next, the powder taken out from the pot was filled in a graphite die having a diameter of 180 mm and molded and sintered using a hot press apparatus. The hot press conditions were a vacuum atmosphere, a holding temperature of 1400 ° C., and a pressure of 250 kgf / cm ² was applied from the start of temperature rise to the end of holding.

The sintered body thus produced was subjected to density measurement by the Archimedes method, and as a result, it had a relative density of 98%. Here, the relative density is a value obtained by dividing the actually measured density of the target by the calculated density (also called the theoretical density). The calculation density is a density when it is assumed that the target components are mixed together without diffusing or reacting with each other, and the formula: calculation density = Σ (molecular weight of the component × molar ratio of the component) / Σ ( (Molecular Weight of Constituent Component × Molar Ratio of Constituent Component / Theoretical Density of Constituent Component) The theoretical density of MgO was 3.585 g / cm ³ and the theoretical density of TiO was 4.93 g / cm ³ . The same applies to the following examples and comparative examples.
Moreover, it was 0.01 ohm * cm as a result of measuring the bulk resistance of a sintered compact by the 4-terminal method. Further, when the cross section of this sintered body was polished and the center portion was observed with a laser microscope, two phases of MgO phase and TiO phase could be observed, and the region where the longest diameter of the MgO phase was 50 μm or more, 30 μm or more, ^They were 5 / mm ² and 15 / mm ² , respectively.

Furthermore, the sintered body was polished into a target shape with a grinder to produce a disk-shaped target. This was attached to a DC sputtering apparatus, and sputtering was performed. The sputtering conditions were sputtering power: 0.5 kW, Ar gas pressure: 5 Pa, and a film was formed on a silicon substrate for 30 seconds. The number of particles adhering to the substrate was measured with a particle counter. The number of particles at this time was 120.

(Example 2)
As raw material powder, TiO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), an average particle diameter of 20 μm and a purity of 3N (99.9%) was prepared. And these raw material powders were prepared so that it might become the composition ratio described in Table 1.
Next, the weighed powder was enclosed in a 10-liter ball mill pot together with zirconia balls as a grinding medium in an Ar atmosphere, and rotated and mixed and ground for 20 hours or more so that both powders were uniformly dispersed.
Next, the powder taken out from the pot was filled in a graphite die having a diameter of 180 mm and molded and sintered using a hot press apparatus. The hot press conditions were a vacuum atmosphere and a holding temperature of 1400 ° C., and a pressure of 300 kgf / cm ² was applied from the start of temperature rise to the end of holding.

As a result of measuring the density by the Archimedes method, the sintered body thus produced had a relative density of 98%. Moreover, it was 0.003 ohm * cm as a result of measuring the bulk resistance of a sintered compact by the 4-terminal method. Moreover, the cross section of this sintered compact was grind | polished and the center part was observed with the laser microscope. The result is shown in FIG. As shown in FIG. 1, two phases of MgO phase (dark gray portion) and TiO phase (light gray portion) were observed. In addition, the regions where the longest diameter of the MgO phase is 50 μm or more and 30 μm or more are one and two, respectively, as shown in FIG. 2, and when the image region is converted into an area per 1 mm ² , three regions each. was / mm2,5 cells / mm ^2. In other examples and comparative examples (except for comparative example 1), it was confirmed that the structure image of the same magnification as in FIG. 1 was formed of two phases of MgO phase and TiO phase. In the image area with the same magnification, the number of MgO phases having the longest diameters of 50 μm or more and 30 μm or more was counted, and this was converted into the area per 1 mm ² to obtain the number per unit area.

Furthermore, the sintered body was polished into a target shape with a grinder to produce a disk-shaped target. This was attached to a DC sputtering apparatus, and sputtering was performed. The sputtering conditions were sputtering power: 0.5 kW, Ar gas pressure: 5 Pa, and a film was formed on a silicon substrate for 30 seconds. The number of particles adhering to the substrate was measured with a particle counter. The number of particles at this time was 51.

(Example 3)
As raw material powder, TiO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), an average particle diameter of 30 μm, and a purity of 3N (99.9%) was prepared. And these raw material powders were prepared so that it might become the composition ratio described in Table 1.
Next, the weighed powder was enclosed in a 10-liter ball mill pot together with zirconia balls as a grinding medium in an Ar atmosphere, and rotated and mixed and ground for 20 hours or more so that both powders were uniformly dispersed.
Next, the powder taken out from the pot was filled in a graphite die having a diameter of 180 mm and molded and sintered using a hot press apparatus. The hot press conditions were a vacuum atmosphere, a holding temperature of 1400 ° C., and a pressure of 250 kgf / cm ² was applied from the start of temperature rise to the end of holding.

The sintered body thus produced was subjected to density measurement by Archimedes method, and as a result, it had a relative density of 99.5%. Moreover, as a result of measuring the bulk resistance of the sintered body by the 4-terminal method, it was 0.002 Ω · cm. Further, when the cross section of this sintered body was polished and the center portion was observed with a laser microscope, two phases of MgO phase and TiO phase could be observed, and the region where the longest diameter of the MgO phase was 50 μm or more, 30 μm or more, ^They were 0 / mm ² and 5 / mm ² , respectively.

Furthermore, the sintered body was polished into a target shape with a grinder to produce a disk-shaped target. This was attached to a DC sputtering apparatus, and sputtering was performed. The sputtering conditions were sputtering power: 0.5 kW, Ar gas pressure: 5 Pa, and a film was formed on a silicon substrate for 30 seconds. The number of particles adhering to the substrate was measured with a particle counter. The number of particles at this time was 46.

Example 4
As raw material powder, TiO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), an average particle diameter of 30 μm, and a purity of 3N (99.9%) was prepared. And these raw material powders were prepared so that it might become the composition ratio described in Table 1.
Next, the weighed powder was sealed in a 10-liter ball mill pot together with zirconia balls as a grinding medium in an Ar atmosphere, and rotated and mixed and ground for 10 hours so that both powders were uniformly dispersed.
Next, the powder taken out from the pot was filled in a graphite die having a diameter of 180 mm and molded and sintered using a hot press apparatus. The hot press conditions were a vacuum atmosphere, a holding temperature of 1400 ° C., and a pressure of 250 kgf / cm ² was applied from the start of temperature rise to the end of holding.

The sintered body thus produced was subjected to density measurement by Archimedes method, and as a result, it had a relative density of 99.5%. Moreover, as a result of measuring the bulk resistance of the sintered body by the 4-terminal method, it was 0.0005 Ω · cm. Further, when the cross section of this sintered body was polished and the center portion was observed with a laser microscope, two phases of MgO phase and TiO phase could be observed, and the region where the longest diameter of the MgO phase was 50 μm or more, 30 μm or more, ^They were 0 / mm ² and 0 / mm ² , respectively.

Furthermore, the sintered body was polished into a target shape with a grinder to produce a disk-shaped target. This was attached to a DC sputtering apparatus, and sputtering was performed. The sputtering conditions were sputtering power: 0.5 kW, Ar gas pressure: 5 Pa, and a film was formed on a silicon substrate for 30 seconds. The number of particles adhering to the substrate was measured with a particle counter. The number of particles at this time was 22.

(Comparative Example 1)
As the raw material powder, only MgO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%) was prepared. Then, this powder was enclosed in a 10-liter ball mill pot together with zirconia balls as a grinding medium, and rotated for 10 hours for grinding.
Next, the powder taken out from the pot was filled in a graphite die having a diameter of 180 mm and molded and sintered using a hot press apparatus. The hot pressing conditions were a vacuum atmosphere and a holding temperature of 1500 ° C., and pressurization was performed at 300 kgf / cm ² from the start of temperature rise to the end of holding.
The sintered body thus produced was subjected to density measurement by Archimedes method, and as a result, it had a relative density of 99%. Moreover, although the bulk resistance measurement of the sintered compact was performed by the 4-terminal method, the resistance value was high and could not be measured.
This sintered body was cut into a target shape with a lathe to produce a disk-shaped target. This was attached to a DC sputtering apparatus and sputtering was performed, but DC sputtering could not be performed.

(Comparative Example 2)
As raw material powder, TiO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), an average particle diameter of 25 μm, and a purity of 3N (99.9%) was prepared. And these raw material powders were prepared so that it might become the composition ratio described in Table 1.
Next, the weighed powder was enclosed in a 10-liter ball mill pot together with zirconia balls as a grinding medium in an Ar atmosphere, and rotated and mixed and ground for 20 hours or more so that both powders were uniformly dispersed.
Next, the powder taken out from the pot was filled in a graphite die having a diameter of 180 mm and molded and sintered using a hot press apparatus. The hot press conditions were a vacuum atmosphere and a holding temperature of 1400 ° C., and a pressure of 300 kgf / cm ² was applied from the start of temperature rise to the end of holding.

As a result of measuring the density by the Archimedes method, the sintered body thus produced had a relative density of 96%. Moreover, as a result of measuring the bulk resistance of the sintered body by the 4-terminal method, the resistance value was high and could not be measured. Further, when the cross section of this sintered body was polished and the center portion was observed with a laser microscope, two phases of MgO phase and TiO phase could be observed, and the region where the longest diameter of the MgO phase was 50 μm or more, 30 μm or more, ^They were 13 / mm ² and 35 / mm ² , respectively.

The sintered body was polished into a target shape with a grinding machine to produce a disk-shaped target. This was attached to a DC sputtering apparatus and sputtering was performed, but DC sputtering could not be performed.

(Comparative Example 3)
As raw material powder, TiO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), an average particle diameter of 100 μm, and a purity of 3N (99.9%) was prepared. And these raw material powders were prepared so that it might become the composition ratio described in Table 1.
Next, the weighed powder was sealed in a 10-liter ball mill pot together with zirconia balls as a grinding medium in an Ar atmosphere, and mixed and pulverized by rotating for 5 hours so that both powders were uniformly dispersed.
Next, the powder taken out from the pot was filled in a graphite die having a diameter of 180 mm and molded and sintered using a hot press apparatus. The hot press conditions were a vacuum atmosphere and a holding temperature of 1400 ° C., and a pressure of 300 kgf / cm ² was applied from the start of temperature rise to the end of holding.

The sintered body thus produced was measured for density by the Archimedes method, and as a result, it had a relative density of 97%. Moreover, as a result of measuring the bulk resistance of the sintered body by the four-terminal method, it was 0.007 Ω · cm. Further, when the cross section of this sintered body was polished and the center portion was observed with a laser microscope, two phases of MgO phase and TiO phase could be observed, and the region where the longest diameter of the MgO phase was 50 μm or more, 30 μm or more, ^They were 25 / mm ² and 53 / mm ² , respectively.

Furthermore, the sintered body was polished into a target shape with a grinder to produce a disk-shaped target. This was attached to a DC sputtering apparatus, and sputtering was performed. The sputtering conditions were sputtering power: 0.5 kW, Ar gas pressure: 5 Pa, and a film was formed on a silicon substrate for 30 seconds. The number of particles adhering to the substrate was measured with a particle counter. The number of particles at this time was 2000.

(Comparative Example 4)
As raw material powder, TiO powder having an average particle diameter of 1 μm and a purity of 4N (99.99%), an average particle diameter of 100 μm, and a purity of 3N (99.9%) was prepared. And these raw material powders were prepared so that it might become the composition ratio described in Table 1.
Next, the weighed powder was sealed in a 10-liter ball mill pot together with zirconia balls as a grinding medium in an Ar atmosphere, and mixed and pulverized by rotating for 5 hours so that both powders were uniformly dispersed.
Next, the powder taken out from the pot was filled in a graphite die having a diameter of 180 mm and molded and sintered using a hot press apparatus. The hot press conditions were a vacuum atmosphere and a holding temperature of 1400 ° C., and a pressure of 300 kgf / cm ² was applied from the start of temperature rise to the end of holding.

The sintered body thus produced was subjected to density measurement by Archimedes method, and as a result, it had a relative density of 99.5%. Moreover, as a result of measuring the bulk resistance of the sintered body by the 4-terminal method, it was 0.002 Ω · cm. Moreover, when the cross section of this sintered body was polished and observed with a laser microscope, two phases of MgO phase and TiO phase could be observed, and the maximum diameter of the MgO phase was 15 μm or more and 15 μm or more, respectively. / Mm ² and 41 pieces / mm ² .

Furthermore, the sintered body was polished into a target shape with a grinder to produce a disk-shaped target. This was attached to a DC sputtering apparatus, and sputtering was performed. The sputtering conditions were sputtering power: 0.5 kW, Ar gas pressure: 5 Pa, and a film was formed on a silicon substrate for 30 seconds. The number of particles adhering to the substrate was measured with a particle counter. The number of particles at this time was 500.

Since the MgO—TiO sintered body of the present invention can be DC-sputtered, the film formation rate can be remarkably increased compared with the case where the conventional MgO sintered body is RF-sputtered, and the productivity is greatly improved. An effect is obtained. Moreover, since DC sputtering can be realized by using an inexpensive DC power source, existing equipment can be used as it is, and the cost of capital investment can be reduced.
As described above, the MgO—TiO sintered body of the present invention is a magnesium oxide-based sputtering used for forming a magnetic recording medium for a magnetic disk device or a thin film for an electro device such as a tunnel magnetoresistive effect (TMR) element. Useful as a target. In addition, as a conductive ceramic material that could not be realized with conventional insulating MgO, it can also be used in new fields such as static electricity removal and heat-resistant members.

Claims

An MgO—TiO sintered body containing 25 to 90 mol% of TiO, with the balance being MgO and inevitable impurities.
2. The MgO—TiO sintered body according to claim 1, wherein the relative density is 95% or more.
The MgO-TiO sintered body according to claim 1 or 2, wherein the bulk resistivity is 10 Ω · cm or less.
The TiO phase and the MgO phase exist in two phases, and the region where the longest diameter of the MgO phase is 50 µm or more is 10 or less per 1 mm 2. MgO—TiO sintered body.
A method for producing a sintered compact for sputtering containing 10 mol% or more and 90 mol% or less of TiO in MgO, comprising a raw material powder comprising an MgO powder having an average particle diameter of 10 μm or less and a TiO powder having an average particle diameter of 50 μm or less A method for producing an MgO—TiO sintered body, comprising mixing and hot pressing at a temperature of 1250 to 1450 ° C. and a pressure of 200 kgf / cm 2 or more.