JP5727130B2 - Composite oxide sintered body and use thereof - Google Patents

Description

  The present invention relates to a composite oxide sintered body and a sputtering target made of the composite oxide sintered body, and particularly to a zinc oxide-based sintered body and a sputtering target made of the sintered body.

  The transparent conductive film has high transmittance in the visible light range and high conductivity, and is used for electrodes of various light receiving elements such as liquid crystal display elements and solar cells, and is also a heat ray reflective film for automobiles and building materials. -Widely used in anti-fogging films and transparent heating elements for anti-fogging such as frozen showcases.

  Examples of such transparent conductive films include indium oxide films containing tin as a dopant, indium oxide films containing zinc as a dopant, and zinc oxide films containing at least one group III element in the periodic table as a dopant. It has been.

  An indium oxide film containing tin as a dopant is called an ITO film, and a low resistance film can be easily obtained. However, since indium, which is a raw material for the ITO film, is a rare metal and expensive, there is a limit to cost reduction when this film is used. Moreover, since indium has a small amount of resource reserves and can only be obtained as a by-product such as zinc ore treatment, it is difficult to significantly increase the ITO film production and to stably supply it. An indium oxide film containing zinc as a dopant is referred to as an IZO film, and an excellent low-resistance film can be obtained. However, as with an ITO film, there is a problem of indium as a raw material.

  Therefore, development of materials for transparent conductive films in place of ITO has been actively promoted. Among them, zinc oxide films mainly composed of zinc oxide and containing Group III elements of the periodic table are made of zinc, which is the main raw material. Because it is extremely inexpensive and has a large amount of reserves and production, there are no problems such as depletion of resources and concerns about stable supply like ITO films, it is inexpensive, chemically stable, transparent, conductive It is attracting attention because of its superiority (see, for example, Patent Document 1).

  By the way, zinc oxide (ZnO) is an oxide semiconductor, and intrinsic defects such as oxygen vacancies due to deviation from the stoichiometric composition form donor levels and exhibit n-type characteristics. When zinc oxide contains a Group III element in the periodic table, conduction electrons increase and specific resistance decreases. Examples of Group III elements in the periodic table included in zinc oxide include aluminum (for example, see Patent Document 1 and Patent Document 2), gallium (for example, see Patent Document 3), boron (for example, see Patent Document 4), and the like. It has been known.

  Conventionally known zinc oxide-based sputtering targets, when used as thin film forming means such as transparent conductive films, due to the abnormal discharge phenomenon that occurs during sputtering, due to the decrease in the operating rate of the sputtering apparatus and the influence of the generated particles There are problems such as a decrease in product yield.

As a means for suppressing such an abnormal discharge phenomenon that occurs during sputtering, for example, Patent Document 1 proposes an effect of suppressing the density of a sintered body by increasing the density of the manufacturing method. Further, for example, in Patent Document 5, the sintered body is densified, and the aluminum component aggregation diameter caused by aluminum oxide added as an oxide of a group III element of the periodic table is suppressed to 5 μm or less at maximum. Further suppression has been shown. Furthermore, in patent document 6, the abnormal discharge during sputtering was suppressed and humidity resistance was improved by making the average particle diameter of ZnAl ₂ O ₄ particles made of zinc oxide and additive aluminum oxide to be 0.5 μm or less. It has been shown to improve thin film manufacturing yield.

Japanese Patent No. 2805813 JP-A-6-2130 JP-A-6-25838 JP 2004-175616 A Japanese Patent No. 3864425 JP 2006-200016 A

  However, by simply increasing the density of the sintered body and controlling the maximum value of the aggregate diameter derived from the additive elements in the sintered body, or by significantly reducing the average particle diameter of the second component particles consisting of zinc oxide and additives, Occurrence of abnormal discharge phenomenon during sputtering cannot be completely avoided, resulting in a decrease in yield due to scattered particles, and there is a problem that productivity reduction cannot be avoided. There is a need to suppress this.

  In view of such a background, as a result of intensive studies, the present inventors significantly reduced the abnormal discharge phenomenon during sputtering by forming a film using a sputtering target made of a specific composite oxide sintered body. As a result, the present invention has been completed.

  That is, the present invention relates to (A) particles containing zinc oxide and having an average particle diameter of 10 μm or less and having a hexagonal wurtzite structure, and (B) a metal element M (where M represents aluminum and / or gallium). Is a composite oxide sintered body composed of particles having a spinel structure with a maximum particle size of 5 μm or less, and when the zinc and the metal element M constituting the sintered body are represented by an atomic ratio, M / ( Zn + M) = 0.006 to 0.07, and the distance between the particles having a spinel structure in the sintered body is 0.5 μm or more and the number frequency is 10% or more. This is a composite oxide sintered body.

  Further, according to the present invention, when an oxide powder of zinc oxide powder and metal element M (wherein M represents aluminum and / or gallium) is represented by an atomic ratio, M / (Zn + M) = 0.006-0. The composite oxide molded body described above, which is mixed by a wet bead mill using beads having a diameter of 1.0 mmφ or less so as to be in the range of 07, and the resulting slurry is molded after being dried or fired. It is a manufacturing method.

  Furthermore, the present invention is a sputtering target comprising the above-described composite oxide sintered body.

  Moreover, this invention is a manufacturing method of the thin film characterized by using the above-mentioned sputtering target. Hereinafter, the present invention will be described in detail.

  The average particle size and the maximum particle size of the particles in the composite oxide sintered body in the present invention are measured as follows. That is, after cutting the composite oxide sintered body of the present invention into an appropriate size, the observation surface is polished, and then chemical etching is performed with a dilute acetic acid solution to clarify the grain boundaries. This sample is taken using EPMA or SEM / EDS, and an observation photograph of the polished surface of the sintered body is taken and the composition of each particle is confirmed. For the average particle size of the particles having a hexagonal wurtzite structure, the major axis of 500 or more of the particles in the observation photograph was obtained, and the average was taken as the average particle size. The maximum particle size of the particles having a spinel structure was determined by obtaining the major axis of 500 or more of the particles in the observation photograph, and taking the maximum value as the maximum particle size.

  As a constituent of the composite oxide sintered body of the present invention, (A) it is essential that the particles have a hexagonal wurtzite structure containing zinc oxide and having an average particle size of 10 μm or less. Thereby, when used as a target, abnormal discharge can be suppressed. Here, particles containing zinc oxide and having a structure attributed to a hexagonal wurtzite structure are substances that exhibit a diffraction pattern attributed to a hexagonal wurtzite structure of zinc oxide in an X-ray diffraction test. , SEM / EDS, EPMA, SPM etc. were confirmed.

  Further, as a constituent of the composite oxide sintered body of the present invention, (B) particles containing a metal element M (where M represents aluminum and / or gallium) and having a spinel structure with a maximum particle size of 5 μm or less It is essential. Thereby, abnormal discharge can be suppressed when used as a target. Here, the particle having a spinel structure is a substance showing a diffraction pattern attributed to a spinel structure compound in an X-ray diffraction test, and has been confirmed by analysis with SEM / EDS, EPMA, SPM or the like. When the maximum particle size of the particles having a spinel structure is 3 μm or less, abnormal discharge is further suppressed, which is particularly preferable.

The particles having the spinel structure must contain the metal element M (where M represents aluminum and / or gallium), and in this case, relatively stable discharge characteristics are easily obtained. As the metal element M, aluminum is preferable. This is because aluminum is easy to handle, the raw materials are inexpensive, and there is no problem in productivity. At this time, particles having a spinel structure are mainly expressed as ZnAl ₂ O ₄ .

  The content of the metal element M satisfies M / (Zn + M) = 0.006 to 0.07 when the zinc constituting the composite oxide sintered body of the present invention and the metal element M are represented by an atomic ratio. Is. By setting it as such a range, when it forms into a film using the sputtering target which consists of complex oxide sintered compact of this invention, it is possible to make the resistivity of the obtained thin film low.

  Note that the complex oxide sintered body of the present invention may contain other elements, and examples thereof include Ti, Zr, In, Si, Ge, Sn, V, Cr, W, and the like. it can. For example, In may be present in particles having a hexagonal wurtzite structure in the composite oxide sintered body of the present invention.

  The inter-particle distance between the particles having a spinel structure in the composite oxide sintered body of the present invention is 10% or more in terms of the number frequency of 0.5 μm or more. By forming such a dispersed state with a large interparticle distance, the abnormal discharge phenomenon during sputtering can be further suppressed when a film is formed using a sputtering target comprising the composite oxide sintered body of the present invention. It becomes possible.

  In the present invention, the interparticle distance between particles having a spinel structure refers to the distance between a particle having a spinel structure and a particle having a spinel structure closest to the particle, and the method for obtaining the distance is as follows. It is. That is, the interior of the composite oxide sintered body of the present invention is mirror-polished at 500 μm or more from the burned surface, and a unit area of 20 μm × 25 μm is photographed on the surface by a composition mapping diagram by EPMA and a secondary electron image by a scanning microscope. Then, the distance between particles having a spinel structure can be determined by comparing the two images.

  For the composition mapping diagram and secondary electron image photographing, a magnification of 2000 times or more is preferable. By observing at this magnification, the measurement error can be reduced. Further, if the unit area is 20 μm × 25 μm, it can be considered as a representative value of the interparticle distance between particles having a spinel structure in the composite oxide sintered body of the present invention. As for the measurement location, there is no problem even if measurement is simple at only one location, but it is usually preferable to measure 6 locations.

  In the present invention, the particles having a spinel structure may be primary particles or secondary particles, and any of them may satisfy the provisions of the present invention.

  Next, a method for producing the composite oxide sintered body of the present invention will be described.

As the raw material powder, zinc oxide powder and metal element M oxide powder are used. These powders preferably have a BET value of 10 to 20 m ² / g in view of handleability, and this makes it easy to obtain the composite oxide sintered body of the present invention. If BET value is less powder than ^{10 m} 2 / g, BET value by performing the pulverization treatment is preferably used after a powder of 10 to 20 m ² / g. Although it is possible to use a powder having a BET value larger than 20 m ² / g, since the powder becomes bulky, it is preferable to perform a consolidation treatment or the like in order to improve handleability.

  Next, when this raw material powder is represented by atomic ratio, it mixes so that it may become M / (Zn + M) = 0.006-0.07. Mixing is performed by a wet bead mill using beads of 1 mmφ or less. It is preferable to use beads such as zirconia, alumina, and nylon resin.

  When mixing, an additive may be allowed to coexist in the slurry. As additives, organic additives generally called binders, dispersants, plasticizers, antifoaming agents and the like are preferably used. Among these, additives such as polycarboxylic acid-based, acrylic-based, alcohol-based, water-soluble waxes, and emulsion-based additives are preferable. Specifically, polycarboxylic acid ammonium salt, polyacrylic acid, acrylic acid-methacrylic acid copolymer Polyvinyl alcohol, polyethylene glycol, stearic acid emulsion and the like are preferable. These additives can be used alone or in combination of two or more. The addition amount is preferably 0.3% by weight or less in terms of solid content with respect to the raw material powder.

In mixing, it is important to uniformly disperse each raw material powder in the slurry. Therefore, the slurry viscosity is preferably 2000 mPa · s or less, and mixing is preferably performed so that the BET value of the raw material powder is increased by 2 m ² / g or more by mixing. At this time, the solid content concentration in the slurry is preferably 50% by weight or more and pH = 7 to 11. The reason why the solid content concentration is 50% by weight or more is to improve productivity, and the pH is set to 7 to 11 in order to consider the handleability of the raw material zinc oxide powder. In addition, the BET value before mixing uses the value calculated | required by weight composition ratio conversion of the raw material powder, and the BET value after mixing is measured after drying a slurry.

  The mixing operation is preferably a batch operation in order to further improve the uniformity. That is, when mixing one lot of raw material powder, each raw material powder is divided into several parts so that each has the desired composition, and each is first mixed and finally mixed into one lot. Is the method.

  Next, the uniformly mixed slurry is formed by a wet bead mill. In a wet molding method such as cast molding, the slurry can be used as it is, but in the case of dry molding, it needs to be dried. This drying method is not particularly limited, and examples thereof include filtration drying, fluidized bed drying, and spray drying. Above all, spray drying with a spray dryer is highly useful as a suitable drying method when dry molding is used because of high productivity and good fluidity of the resulting granulated powder.

  As the molding method, it is important to appropriately select a molding method that can be molded into a desired shape, and is not particularly limited. Examples thereof include dry and wet molding methods such as press molding and cast molding. The molding pressure is not particularly limited as long as it does not cause cracks and can be handled, but it is more preferable to increase the molding density as much as possible. Therefore, it is also possible to use a method such as cold isostatic pressing (CIP).

Next, the obtained molded body is fired. The firing temperature is preferably from 800 to 1600 ° C., and more preferably from 1100 to 1400 ° C., since the volatilization disappearance peculiar to the zinc oxide-based composite oxide is suppressed and the sintered density can be relatively increased. The sintered density is preferably 4.7 g / cm ³ or more, which makes it easy to handle and can reduce damage during sputtering.

  The firing time is not particularly limited, but is usually 1 to 48 hours, particularly preferably 3 to 24 hours. This ensures the homogeneity in the complex oxide sintered body of the present invention and considers the influence on the productivity.

  The rate of temperature increase is not particularly limited, but is preferably 100 ° C./h or less in a temperature range of 800 ° C. or higher. This is for suppressing the grain growth of particles having a spinel structure in the composite oxide sintered body of the present invention and enhancing the homogeneity.

  Although the firing atmosphere is not particularly limited, for example, the atmosphere, oxygen, inert gas atmosphere, or the like is appropriately selected. Moreover, the pressure at the time of baking is not specifically limited, In addition to a normal pressure, baking in a pressurization and pressure reduction state is also possible. Moreover, HIP method, hot press sintering, etc. are also possible.

  By forming a film using the sputtering target composed of the composite oxide sintered body of the present invention, the abnormal discharge phenomenon during sputtering can be remarkably reduced, and the decrease in yield and productivity due to scattered particles are suppressed at that time. It becomes possible.

  The present invention will be specifically described by the following examples, but the present invention is not limited thereto.

Example 1
Zirconia beads having a diameter of 0.5 mmφ were used so that the composition shown in Table 1 was made of a zinc oxide powder having a BET of ⁴ m ² / g and a purity of 99.8% and an aluminum oxide powder having a BET of 14 m ² / g and a purity of 99.99%. Mix in wet bead mill. At this time, polycarboxylic acid ammonium salt was added as a dispersant in an amount of 0.2% by weight in terms of solid content with respect to the raw material powder. The obtained slurry viscosity was 17 mPa · s, pH = 9.5, and the BET value after mixing was 6.9 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1400 ° C. in a nitrogen atmosphere for 5 hours. Table 1 shows the characteristics of the obtained sintered body. That is, by analysis with XRD, SEM / EDS, EPMA, particles having a hexagonal wurtzite structure containing zinc oxide and particles having a spinel structure are observed and mapped, and particles having a hexagonal wurtzite structure are observed. The average particle size, the maximum particle size of particles having a spinel structure, and the interparticle distance of particles having a spinel structure were determined. The inter-particle distance of the particles having a spinel structure was determined by the above-described method. The case where the number of particles having a diameter of 0.5 μm or more was 10% or more was “◯”, and the case where the number was less than 10% was “X”.

This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed. The sputtering conditions were a DC magnetron sputtering apparatus, a substrate temperature of 200 ° C., an ultimate vacuum of 5 × 10 ⁻⁵ Pa, a sputtering gas Ar, a sputtering gas pressure of 0.5 Pa, and a DC power of 300 W. The discharge characteristics were evaluated as the number of abnormal discharges that occurred per unit time, and less than 10 times / hour was “◯”, less than 10 to 100 times / hour was “Δ”, and more than 100 times / hour was “x”. . The results are shown in Table 1. In addition, the amount of M described in Table 1 indicates M / (Zn + M) when the zinc oxide powder and the oxide powder of the metal element M used are represented by an atomic ratio.

Example 2
BET 12.7 m ² / g, zinc oxide powder with a purity of 99.8% and BET 14 m ² / g, aluminum oxide powder with a purity of 99.99% are made of 0.5 mmφ alumina beads so as to have the composition shown in Table 1. It mixed with the used wet bead mill. At this time, polycarboxylic acid ammonium salt was added as a dispersant in an amount of 0.2% by weight in terms of solid content with respect to the raw material powder. The obtained slurry viscosity was 23 mPa · s, pH = 9.2, and the BET value after mixing was 15.3 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1400 ° C. in a nitrogen atmosphere for 3 hours. Table 1 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 3
BET ⁴ m ² / g, 99.8% purity zinc oxide powder and BET 14 m ² / g, 99.99% purity aluminum oxide powder were used with 1.0 mmφ alumina beads so that the composition shown in Table 1 was obtained. Mix in wet bead mill. At this time, the slurry viscosity was 10 mPa · s, pH = 8.9, and the BET value after mixing was 6.8 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1200 ° C. in a nitrogen atmosphere for 5 hours. Table 1 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 4
BET ⁴ m ² / g, zinc oxide powder with a purity of 99.8% and BET 14 m ² / g, aluminum oxide powder with a purity of 99.99% were weighed to the composition shown in Table 1, and divided into two equal parts. Were mixed in a wet bead mill using 0.3 mmφ zirconia beads. Further, both were combined into one lot and mixed in the same manner using a wet bead mill. At this time, the slurry viscosity was 800 mPa · s, pH = 9.4, and the BET value after mixing was 7.9 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1500 ° C. in an air atmosphere for 12 hours. Table 1 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 5
BET ⁴ m ² / g, zinc oxide powder with a purity of 99.8% and BET 14 m ² / g, aluminum oxide powder with a purity of 99.99% were weighed to have the composition shown in Table 1, and divided into 4 equal parts. Were mixed in a wet bead mill using 0.3 mmφ alumina beads. Further, they were combined into one lot and similarly mixed by a wet bead mill. At this time, 0.1 wt% of polycarboxylic acid ammonium salt was added as a dispersant in terms of solid content to the raw material powder. The obtained slurry viscosity was 1225 mPa · s, pH = 9.8, and the BET value after mixing was 12.8 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1400 ° C. in a nitrogen atmosphere for 5 hours. Table 1 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 6
BET ⁴ m ² / g, 99.8% purity zinc oxide powder and BET 14 m ² / g, 99.99% purity aluminum oxide powder were used with 1.0 mmφ alumina beads so that the composition shown in Table 1 was obtained. Mix in wet bead mill. At this time, 0.15% by weight of polycarboxylic acid ammonium salt as a dispersant was added to the raw material powder in terms of solid content. The obtained slurry viscosity was 17 mPa · s, pH = 9.1, and the BET value after mixing was 6.9 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1100 ° C. in a nitrogen atmosphere for 5 hours. Table 1 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 7
BET4m ² / g, 99.8% pure zinc oxide powder and BET14m ² / g, 99.99% pure aluminum oxide powder 0.5mmφ alumina beads were used so as to have the composition shown in Table 1. Mix in wet bead mill. At this time, a polycarboxylic acid ammonium salt as a dispersant is added to the raw material powder in a solid content conversion of 0.00. 1% by weight was added. The obtained slurry viscosity was 1800 mPa · s, pH = 9.3, and the BET value after mixing was 7.3 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1400 ° C. in a nitrogen atmosphere for 5 hours. Table 1 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 8
BET4m ² / g, 99.8% purity zinc oxide powder and BET8m ² / g, 99.99% purity gallium oxide powder 0.4mmφ alumina beads were used so as to have the composition shown in Table 1. Mix in wet bead mill. At this time, 0.15% by weight of polycarboxylic acid ammonium salt as a dispersant was added to the raw material powder in terms of solid content. The obtained slurry viscosity was 250 mPa · s, pH = 9.1, and the BET value after mixing was 6.6 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1400 ° C. in a nitrogen atmosphere for 5 hours. Table 1 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 9
Table 1 shows a zinc oxide powder having a BET of ⁴ m ² / g and a purity of 99.8% and a BET of 14 m ² / g, an aluminum oxide powder having a purity of 99.99%, and a gallium oxide powder having a BET of 8 m ² / g and a purity of 99.99%. The mixture was mixed by a wet bead mill using 0.5 mmφ alumina beads so as to have a composition. At this time, polycarboxylic acid ammonium salt was added as a dispersant in an amount of 0.2% by weight in terms of solid content with respect to the raw material powder. The obtained slurry viscosity was 55 mPa · s, pH = 9.3, and the BET value after mixing was 6.9 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1400 ° C. in a nitrogen atmosphere for 5 hours. Table 1 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

比較例１
ＢＥＴ４ｍ^２／ｇ、純度９９．８％の酸化亜鉛粉末とＢＥＴ１４ｍ^２／ｇ、純度９９．９９％の酸化アルミニウム粉末を表２に示した組成になるように１．０ｍｍφのジルコニア製ビーズを用いた湿式ビーズミルで混合した。得られたスラリー粘度は３５００ｍＰａ・ｓ、ｐＨ＝９．８、混合後のＢＥＴ値は５．１ｍ^２／ｇであった。得られたスラリーをスプレードライヤーで噴霧乾燥した後、３．０ｔｏｎ／ｃｍ^２で直径１５０ｍｍ、厚さ１２ｍｍにＣＩＰ成形した。焼結は１４００℃、窒素雰囲気で５時間行った。得られた焼結体の特性を表２に示す。

Comparative Example 1
BET4m ² / g, using zirconia beads of 1.0mmφ to a purity of 99.8% zinc oxide powder and BET14m ² / g, a purity of 99.99% aluminum oxide powder to obtain the compositions shown in Table 2 Mix in wet bead mill. The obtained slurry viscosity was 3500 mPa · s, pH = 9.8, and the BET value after mixing was 5.1 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1400 ° C. in a nitrogen atmosphere for 5 hours. Table 2 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 2. Each item described in Table 2 has the same meaning as in Table 1.

Comparative Example 2
Wet bead mill using BET4m ² / g, 99.8% pure zinc oxide powder and BET14m ² / g, 99.99% pure aluminum oxide powder with 3mmφ alumina beads to have the composition shown in Table 2 Mixed. At this time, 0.05% by weight of a polycarboxylic acid ammonium salt as a dispersant was added to the raw material powder in terms of solid content. The obtained slurry viscosity was 14 mPa · s, pH = 9.2, and the BET value after mixing was 5.3 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1400 ° C. in a nitrogen atmosphere for 5 hours. Table 2 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 3
BET4m ² / g, a dry ball mill purity of 99.8% zinc oxide powder and BET14m ² / g, a purity of 99.99% aluminum oxide powder with alumina balls 15mmφ so that the composition shown in Table 2 Mixed. The BET value of the obtained mixed powder was 5.2 m ² / g. This mixed powder was CIP molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1400 ° C. in a nitrogen atmosphere for 5 hours. Table 2 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 4
BET4m ² / g, a wet ball mill to a purity of 99.8% zinc oxide powder and BET14m ² / g, a purity of 99.99% aluminum oxide powder with alumina balls 15mmφ so that the composition shown in Table 2 Mixed. At this time, 0.5 wt% of polycarboxylic acid ammonium salt was added as a dispersant in terms of solid content with respect to the raw material powder. The obtained slurry viscosity was 450 mPa · s, pH = 9.0, and the BET value after mixing was 6.5 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1400 ° C. in a nitrogen atmosphere for 5 hours. Table 2 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 5
BET4m ² / g, a purity of 99.8% zinc oxide powder and BET8m ² / g, a wet bead mill with 99.99% purity gallium oxide powder with zirconia beads 5mmφ so that the composition shown in Table 2 Mixed. The obtained slurry viscosity was 4100 mPa · s, pH = 9.1, and the BET value after mixing was 5.0 m ² / g. The obtained slurry was spray-dried with a spray dryer, and then CIP-molded at 3.0 ton / cm ² to a diameter of 150 mm and a thickness of 12 mm. Sintering was performed at 1400 ° C. in a nitrogen atmosphere for 5 hours. Table 2 shows the characteristics of the obtained sintered body.

  This sintered body was processed into a 4-inch φ size as a target, and sputtering evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

以上の実施例１〜９と比較例１〜５から明らかなように、本発明の複合酸化物焼結体から成るスパッタリングターゲットを用いて成膜することにより、スパッタリング中の異常放電を著しく抑制することが可能である。

As apparent from Examples 1 to 9 and Comparative Examples 1 to 5, the abnormal discharge during sputtering is remarkably suppressed by forming a film using the sputtering target made of the composite oxide sintered body of the present invention. It is possible.

Claims (4)

(A) particles having a hexagonal wurtzite structure containing zinc oxide and having an average particle size of 10 μm or less,
And (B) a metal element M (where, M represents an aluminum) a composite oxide sintered body for a sputtering target maximum particle size containing consists particles having the spinel structure 5 [mu] m,
When the zinc and the metal element M constituting the sintered body are represented by an atomic ratio, M / (Zn + M) = 0.024 to 0.04 , and particles having a spinel structure in the sintered body The composite oxide sintered body for a sputtering target is characterized in that the distance between particles is 0.5% or more and the number frequency is 10% or more. Zinc oxide powder and metal element M (where, M represents an aluminum) oxide powder, so that the range of M / (Zn + M) = 0.024~0.04 when expressed in atomic ratio, 1 A slurry having a slurry viscosity of 2000 mPa · s or less was mixed by a wet bead mill using beads having a diameter of 0.0 mmφ or less so that the BET value was 2 m ² / g or more larger than the weighted average of the BET values of the raw material powder before mixing. The method for producing a composite oxide sintered body for a sputtering target according to claim 1, wherein the composite oxide sintered body is formed after being dried and then fired. A sputtering target comprising the composite oxide sintered body for a sputtering target according to claim 1 . A method for producing a thin film, comprising using the sputtering target according to claim 3 .