TW202041483A - Oxide sintered body, sputtering target, and method for producing sputtering target - Google Patents

Abstract

An oxide sintered body (1) in which the average value of the Vickers Hardness values of the surface of the oxide sintered body (1) is 500 to 900 Hv exclusive.

Description

Oxide sintered body, sputtering target material and manufacturing method of sputtering target material

The invention relates to an oxide sintered body, a sputtering target and a method for manufacturing the sputtering target.

Previously, in display devices such as liquid crystal displays or organic EL (Electroluminescence) displays driven by thin film transistors (hereinafter referred to as "TFT (Thin Film Transistor)"), the channel layer of TFT mainly uses amorphous Quality silicon film or crystalline silicon film.

On the other hand, in recent years, with the demand for high-definition displays, oxide semiconductors have attracted attention as materials used in the channel layer of TFTs.

Among oxide semiconductors, in particular, amorphous oxide semiconductors (In-Ga-Zn-O, abbreviated as "IGZO" hereinafter) including indium, gallium, zinc, and oxygen are used for their high carrier mobility. Preferably used. However, IGZO has the disadvantage of high raw material cost due to the use of In and Ga as raw materials.

From the viewpoint of reducing the cost of raw materials, Zn-Sn-O (hereinafter abbreviated as "ZTO"), or In-Sn-Zn-O with Sn added instead of Ga in IGZO (hereinafter abbreviated as "ITZO") .

Since ITZO exhibits a very high mobility compared with IGZO, it is expected to be a next-generation oxide semiconductor material that is beneficial to the miniaturization of TFTs and the narrowing of panel edges.

However, ITZO has a large thermal expansion coefficient and low thermal conductivity, so there is a problem that it is prone to cracking due to thermal stress during bonding to Cu or Ti backing plates and during sputtering.

In a recent study, it was reported that the biggest problem of oxide semiconductor materials is reliability, which can be improved by densifying the film.

In order to densify the film, high-power film formation is effective. However, in large-scale mass production equipment, the breakage of the end of the target material where the plasma is concentrated becomes a problem, especially the target material of ITZO-based material tends to break easily.

For example, it is described in Non-Patent Document 1 (Journal of the Ceramic Society of Japan, 104, [7], 654-658 (1996)) that in ceramics, there is a proportional relationship between Vickers hardness and tensile strength.

Document 1 (Japanese Patent Laid-Open No. 2012-180247) describes an oxide sintered body composed of zinc oxide, tin oxide, and selected from Al, Hf, Ni, Si, Ga, In, and Ta An oxide sintered body obtained by mixing and sintering oxides of at least one metal (M metal) in the group, and having a Vickers hardness of 400 Hv or more. Document 1 describes that even if such an oxide sintered body is used for film formation by a direct current sputtering method, nodules are not easily generated, and stable discharge can be achieved for a long time.

Document 1 describes that the Vickers hardness of a sputtering target containing an oxide sintered body is specified within a specific range. However, the Vickers hardness measurement in Document 1 sets the oxide sintered body to t/2 (t: Thickness) The value of the position of the surface of the cut surface. Therefore, in Document 1, there is no description about the Vickers hardness in the surface of the oxide sintered body.

In recent years, there has been a demand for a target material that improves the crack resistance during sputtering. Document 1 describes the hypothesis that the hardness of the oxide sintered body can be controlled to suppress nodules. However, there is no method for improving the crack resistance. Record. Further, in Document 1, although there is a description of appropriately controlling the sintering conditions and subsequent heat treatment conditions in order to control the hardness of the oxide sintered body, it is difficult to improve the crack resistance under the conditions described in Document 1.

The object of the present invention is to provide an oxide sintered body and a sputtering target with improved crack resistance, and to provide a method for manufacturing the sputtering target.

[1A]. An oxide sintered body in which the average Vickers hardness of the surface of the oxide sintered body exceeds 500 Hv and does not reach 900 Hv.

[2A]. A sputtering target material comprising the oxide sintered body as [1A].

[1]. A sputtering target material comprising an oxide sintered body, and the average Vickers hardness of the surface of the oxide sintered body exceeds 500 Hv and does not reach 900 Hv.

[2]. The sputtering target of [1] or [2A], wherein the oxide sintered body contains indium, tin, and zinc.

[3]. The sputtering target material of [2], wherein the above-mentioned oxide sintered body further contains X element, which is selected from germanium element, silicon element, yttrium element, zirconium element, aluminum element, magnesium element, and ytterbium element And at least one element in the group consisting of gallium element.

[4]. The sputtering target of [2] or [3], wherein the oxide sintered body satisfies the range of the atomic composition ratio represented by the following formulas (1), (2), and (3). 0.40≦Zn/(In＋Sn＋Zn)≦0.80 (1) 0.15≦Sn/(Sn＋Zn)≦0.40 (2) 0.10≦In/(In＋Sn＋Zn)≦0.35 (3)

[5]. The sputtering target material according to any one of [2] to [4], wherein the oxide sintered body includes a hexagonal layer represented by In ₂ O ₃ (ZnO)m [m=2～7] Shape compound and spinel structure compound represented by Zn ₂ SnO ₄ .

[5A]. The sputtering target material according to any one of [2] to [4], wherein the oxide sintered body comprises a hexagonal layer represented by In ₂ O ₃ (ZnO)m [m=2～7] Shape compound and spinel structure compound represented by Zn _{2 - x} Sn _{1 - y} In _{x + y} O ₄ [0≦x<2, 0≦y<1].

[6]. A method for manufacturing a sputtering target, which is used to manufacture the sputtering target of any one of [1] to [5], [2A] and [5A], and includes the following steps: Granulate the raw material of the above-mentioned oxide sintered body to obtain raw material granulated powder with a particle size of 25 μm or more and 150 μm or less; Filling the raw material granulated powder into a mold, and molding the raw material granulated powder filled in the mold to obtain a molded body; and The above-mentioned molded body is sintered at 1310°C or higher and 1440°C or lower.

[7]. The method for manufacturing a sputtering target as in [6], wherein the particle size of the raw material granulated powder is 25 μm or more and 75 μm or less.

According to one aspect of the present invention, an oxide sintered body and a sputtering target with improved crack resistance can be provided.

According to one aspect of the present invention, a method for manufacturing a sputtering target of one aspect of the present invention can be provided.

The cracks of the sputtering target material start from the weaker part of the target material.

Therefore, the present inventors considered reducing the unevenness of the strength in the sputtering target surface, especially increasing the minimum strength, as a countermeasure to improve the crack resistance.

The inventors of the present inventors conducted intensive research on the manufacturing conditions of sputtering targets, and obtained the following knowledge and insights: By optimizing the particle size and sintering temperature of the raw material granulated powder, the dimension of the sputtering surface of the oxide sintered body The minimum value of the hardness increases, and the average value increases.

In addition, the knowledge that the average value of the Vickers hardness in the oxide sintered body has an optimal range is also obtained. If the Vickers hardness is too high, microcracks will occur in the grinding process of the target material, and the crack resistance will be reduced.

The inventors invented the present invention based on these knowledge findings.

Hereinafter, the embodiment will be described with reference to the drawings and the like. However, it is easy for a professional to understand that the embodiment can be implemented in many different forms, and the form and details can be variously changed without departing from the spirit and scope. Therefore, the present invention is not limited to the description of the following embodiments.

In the diagram, there are situations where the size, layer thickness and area are exaggerated for clarity. Therefore, it is not necessarily limited to this scale. In addition, the drawings are diagrams schematically showing ideal examples, and the present invention is not limited to the shapes and values shown in the drawings.

The ordinal numbers of "No. 1", "No. 2" and "No. 3" used in this manual are marked in order to avoid the confusion of constituent elements, and are not restricted by the law of numbers.

In this manual, etc., the term "membrane" or "thin film" and the term "layer" can be interchanged depending on the situation.

In the sintered body and the oxide semiconductor thin film in this specification, the term "compound" and the term "crystalline phase" can be replaced with each other depending on the situation.

In this specification, "oxide sintered body" may be simply referred to as "sintered body".

In this manual, there are cases where "sputtering target" is simply referred to as "target".

[Sputtering target] The sputtering target material of one embodiment of the present invention (hereinafter, sometimes referred to as the sputtering target material of this embodiment) includes an oxide sintered body.

The sputtering target of this embodiment is obtained, for example, by cutting and grinding a block of an oxide sintered body into a shape suitable as a sputtering target.

In addition, the sputtering target of this embodiment can also be obtained by bonding a sputtering target material obtained by grinding and polishing a block of an oxide sintered body to a backing plate.

Moreover, as another aspect of the sputtering target material of this embodiment, the target material which consists only of an oxide sintered body can also be mentioned.

The shape of the oxide sintered body is not particularly limited.

It may also be a plate-shaped oxide sintered body as shown by reference numeral 1 in FIG. 1.

It may also be a cylindrical oxide sintered body as shown by the symbol 1A in FIG. 2.

When the oxide sintered body is in the shape of a plate, the planar shape of the oxide sintered body may be either a rectangle as shown in symbol 1 in FIG. 1 or a circle as shown in symbol 1B in FIG. 3.

The oxide sintered body may be an integrally molded product, or may be divided into a plurality of pieces as shown in FIG. 4. Each of the oxide sintered bodies (symbol 1C) divided into plural pieces may be fixed to the backing plate 3. In this manner, a sputtering target obtained by joining a plurality of oxide sintered bodies 1C to one backing plate 3 may be referred to as a multi-divided sputtering target. The backing plate 3 is a member for holding and cooling the oxide sintered body. The material of the backing plate 3 is not particularly limited. As the material of the backing plate 3, for example, at least one material selected from the group consisting of Cu, Ti and SUS is used.

(Vickers hardness) In the target material of this embodiment, the average value (H _av ) of the Vickers hardness on the surface of the oxide sintered body exceeds 500 Hv and does not reach 900 Hv. In this specification, the measurement of Vickers hardness is implemented using a Hardness Tester (AKASHI MVK-E3) according to JIS Z 2244:2009. The measurement points are taken along the line of the center of the oxide sintered body (142×305 mm size) from the end of one side every 30 mm, and the average value of the taken data is taken as the dimension of the surface of the oxide sintered body The average value of Hardness (H _av ).

The average value (H _av ) of the Vickers hardness on the surface of the oxide sintered body exceeds 500 Hv, and the sputtering surface of the target has a smaller portion with weaker strength. Therefore, the crack resistance of the sputtering target of this embodiment is improved.

If the Vickers hardness is too high, microcracks may occur during the grinding process. However, in this embodiment, since the average value (H _av ) of the Vickers hardness of the surface of the oxide sintered body is less than 900 Hv, it is possible to suppress the generation of microcracks in the grinding process of the target material. As a result, it is also possible to suppress the decrease in crack resistance due to microcracks.

The average value (H _av ) of the Vickers hardness of the surface of the oxide sintered body is preferably from 520 Hv to 850 Hv, and more preferably from 600 Hv to 750 Hv.

The minimum value (H _min ) of the Vickers hardness on the surface of the oxide sintered body is preferably more than 500 Hv, more preferably more than 600 Hv. If the minimum value of the Vickers hardness (H _min ) exceeds 500 Hv, the weaker part of the sputtering surface of the target material will be less, and the crack resistance will be improved. Furthermore, in this specification, the minimum value of Vickers hardness (H _min ) is to measure the Vickers hardness of 10 parts on the surface of the oxide sintered body, and the Vickers hardness value of the 10 parts is the lowest value.

The maximum value (H _max ) of the Vickers hardness of the surface of the oxide sintered body is preferably less than 900 Hv, more preferably 850 Hv or less. If the minimum value of the Vickers hardness (H _max ) is less than 900 Hv, the generation of micro-cracks in the grinding process of the target is further suppressed, and as a result, the crack resistance is further improved. Furthermore, in this specification, the maximum value of Vickers hardness (H _max ) is to measure the Vickers hardness of 10 parts on the surface of the oxide sintered body, and the value of the Vickers hardness of the 10 parts is the largest. .

(Composition of oxide sintered body) The oxide sintered body of this embodiment preferably contains indium element (In), tin element (Sn), and zinc element (Zn).

The oxide sintered body of this embodiment may contain other metal elements other than In, Sn, and Zn within a range that does not impair the effects of the present invention, and may substantially contain only In, Sn, and Zn, or may be composed only of It is composed of In, Sn and Zn. Here, the term "substantially" means that 95% by mass to 100% by mass (preferably 98% by mass to 100% by mass) of the metal element of the oxide sintered body is indium (In) or tin ( Sn) and zinc element (Zn). The oxide sintered body of this embodiment may contain inevitable impurities in addition to In, Sn, Zn, and oxygen element (O) within a range that does not impair the effects of the present invention. The unavoidable impurities mentioned here refer to elements that are not deliberately added, but are elements that are mixed in raw materials or manufacturing steps.

The oxide sintered body of this embodiment also preferably contains indium element (In), tin element (Sn), zinc element (Zn), and X element.

The oxide sintered body of this embodiment may contain other metal elements other than In, Sn, Zn, and X elements within a range that does not impair the effects of the present invention, or may substantially contain only In, Sn, Zn, and X elements. , Or may be composed of only In, Sn, Zn, and X elements. Here, "substantially" means that 95% by mass to 100% by mass (preferably 98% by mass to 100% by mass) of the metal elements of the oxide sintered body are In, Sn, Zn, and X elements. The oxide sintered body of this embodiment may contain inevitable impurities in addition to In, Sn, Zn, X elements, and oxygen element (O) within the range that does not impair the effects of the present invention. The unavoidable impurities mentioned here refer to elements that are not deliberately added, but are elements that are mixed in raw materials or manufacturing steps.

The X element is selected from germanium (Ge), silicon (Si), yttrium (Y), zirconium (Zr), aluminum (Al), magnesium (Mg), ytterbium (Yb) and gallium ( At least one element in the group consisting of Ga).

Examples of unavoidable impurities include alkali metals (Li, Na, K, Rb, etc.), alkaline earth metals (Ca, Sr, Ba, etc.), hydrogen (H) element, boron (B) element, carbon (C) Element, nitrogen (N) element, fluorine (F) element and chlorine (Cl) element.

The impurity concentration can be measured by ICP (Inductively Coupled Plasma) or SIMS (secondary ion mass spectrometry).

＜Measurement of impurity concentration (H, C, N, F, Si, Cl)＞ The impurity concentration (H, C, N, F, Si, Cl) in the obtained sintered body can be determined by SIMS analysis using a sector-type dynamic secondary ion mass spectrometer (IMS 7f-Auto, manufactured by AMETEK CAMECA) Quantitative evaluation.

Specifically, first, the primary ion Cs ⁺ is used to sputter at an acceleration voltage of 14.5 kV to a depth of 20 μm from the surface of the sintered body of the measurement object. Then, for the grating 100 μm square (100 μm×100 μm size), the measurement area 30 μm square (30 μm×30 μm size), and the depth of 1 μm, sputtering with primary ion on one side while facing impurities (H, C, N, F, Si, Cl) mass spectrum intensity is integrated.

Furthermore, the absolute value of the impurity concentration is calculated from the mass spectrum, and the doping amount of each impurity is controlled by ion implantation and injected into the sintered body to prepare a standard sample with a known impurity concentration. Regarding the standard sample, the mass spectrum intensity of impurities (H, C, N, F, Si, Cl) is obtained by SIMS analysis, and the relationship between the absolute value of the impurity concentration and the mass spectrum intensity is made into a calibration curve.

Finally, use the mass spectrum intensity of the sintered body of the measurement object and the calibration curve to calculate the impurity concentration of the measurement object, and set it as the absolute value of the impurity concentration (atom·cm ^-3 ).

<Measurement of impurity concentration (B, Na)> Regarding the impurity concentration (B, Na) of the obtained sintered body, it is also possible to use a sector-type dynamic secondary ion mass spectrometer (IMS 7f-Auto, manufactured by AMETEK CAMECA) ) Quantitative evaluation of SIMS analysis. The primary ion is set to O ₂ ⁺ , and the acceleration voltage of the primary ion is set to 5.5 kV to perform the mass spectrometry measurement of each impurity. Other than that, the same method as the measurement of H, C, N, F, Si, and Cl Evaluate and obtain the absolute value (atom·cm ^-3 ) of the impurity concentration of the measurement object.

In the oxide sintered body of this embodiment, it is more preferable that the atomic composition ratio of each element satisfies at least one of the following formulas (1) to (3). 0.40≦Zn/(In＋Sn＋Zn)≦0.80 (1) 0.15≦Sn/(Sn＋Zn)≦0.40 (2) 0.10≦In/(In＋Sn＋Zn)≦0.35 (3)

In formulas (1) to (3), In, Zn, and Sn represent the contents of indium, zinc, and tin in the oxide sintered body, respectively.

If Zn/(In+Sn+Zn) is 0.40 or more, a spinel phase is easily generated in the oxide sintered body, and semiconductor characteristics are easily obtained.

If Zn/(In+Sn+Zn) is 0.80 or less, the decrease in strength due to abnormal grain growth of the spinel phase can be suppressed in the oxide sintered body. In addition, if Zn/(In+Sn+Zn) is 0.80 or less, the decrease in the mobility of the oxide semiconductor thin film can be suppressed.

Zn/(In+Sn+Zn) is more preferably 0.50 or more and 0.70 or less.

If Sn/(Sn+Zn) is 0.15 or more, the decrease in strength due to abnormal grain growth of the spinel phase can be suppressed in the oxide sintered body.

If Sn/(Sn+Zn) is 0.40 or less, in the oxide sintered body, the aggregation of tin oxide that causes abnormal discharge during sputtering can be suppressed. Moreover, if Sn/(Sn+Zn) is 0.40 or less, the oxide semiconductor thin film formed by using a sputtering target can be easily etched using weak acids such as oxalic acid. If Sn/(Sn+Zn) is 0.15 or more, the etching rate can be suppressed from becoming too fast, and the control of etching becomes easy.

Sn/(Sn+Zn) is more preferably 0.15 or more and 0.35 or less.

If In/(In+Sn+Zn) is 0.10 or more, the volume resistance of the obtained sputtering target can be reduced. In addition, if In/(In+Sn+Zn) is 0.10 or more, the mobility of the oxide semiconductor thin film can be suppressed from becoming extremely low.

If In/(In+Sn+Zn) is 0.35 or less, it is possible to prevent the film from becoming a conductor during sputtering film formation, and it is easy to obtain characteristics as a semiconductor.

In/(In+Sn+Zn) is preferably 0.10 or more and 0.30 or less.

In the case where the oxide sintered body of the present embodiment contains the X element, it is preferable that the atomic ratio of each element satisfies the following formula (1X). 0.001≦X/(In＋Sn＋Zn＋X)≦0.05 (1X)

(In formula (1X), In, Zn, Sn, and X respectively represent the contents of indium, zinc, tin, and X in the oxide sintered body.)

If it is in the range of the above-mentioned formula (1X), the oxide sintered body of this embodiment can have sufficiently high crack resistance.

The X element is preferably at least one selected from the group consisting of silicon element (Si), aluminum element (Al), magnesium element (Mg), ytterbium element (Yb), and gallium element (Ga).

The X element is more preferably at least one selected from the group consisting of silicon element (Si), aluminum element (Al), and gallium element (Ga).

Aluminum element (Al) and gallium element (Ga) are better because the composition of the oxides used as raw materials is stable and the effect of improving crack resistance is higher.

If X/(In+Sn+Zn+X) is 0.001 or more, the decrease in the strength of the sputtering target can be suppressed. If X/(In+Sn+Zn+X) is 0.05 or less, the oxide semiconductor thin film formed using a sputtering target containing the oxide sintered body can be easily etched using weak acids such as oxalic acid. Furthermore, if X/(In+Sn+Zn+X) is 0.05 or less, it is possible to suppress a decrease in TFT characteristics, especially mobility.

X/(In+Sn+Zn+X) is preferably 0.001 or more and 0.05 or less, more preferably 0.003 or more and 0.03 or less, still more preferably 0.005 or more and 0.01 or less, and still more preferably 0.005 or more and less than 0.01.

When the oxide sintered body of this embodiment contains the X element, the X element may be only one type or two or more types. When two or more types of X elements are included, X in formula (1X) is the total atomic ratio of X elements.

The existence form of the X element in the oxide sintered body is not specifically defined. As the existence form of the X element in the oxide sintered body, for example, a form existing as an oxide, a solid solution form, and a form segregated at grain boundaries can be cited.

The atomic ratio of each metal element of the oxide sintered body can be controlled by the blending amount of raw materials. In addition, the atomic ratio of each element can be determined by quantitative analysis of the contained elements by an inductively coupled plasma emission spectrometer (ICP-AES).

The oxide sintered body of this embodiment preferably contains a spinel structure compound represented by Zn _{2 - x} Sn _{1 - y} In _{x + y} O ₄ [0≦x<2, 0≦y<1]. In this specification, the spinel structure compound may be referred to as a spinel compound. In Zn _{2 - x} Sn _{1 - y} In _{x + y} O ₄ , when x is 0 and y is 0, it is represented by Zn ₂ SnO ₄ .

The oxide sintered body of this embodiment preferably contains a hexagonal layered compound represented by In ₂ O ₃ (ZnO) _m . In this embodiment, in the formula represented by In ₂ O ₃ (ZnO) _m , m is an integer of 2-7, preferably an integer of 3-5. If m is 2 or more, the compound adopts a hexagonal layered structure. If m is 7 or less, the volume resistance of the oxide sintered body becomes low.

The oxide sintered body of the present embodiment more preferably contains a hexagonal layered compound represented by In ₂ O ₃ (ZnO) _m [m=2-7] and a Zn _{2 - x} Sn _{1 - y} In _{x + y} O ₄ [0≦x<2, 0≦y<1] represents the spinel structure compound.

The hexagonal layered compound including indium oxide and zinc oxide is a compound that represents the X-ray diffraction pattern belonging to the hexagonal layered compound in the measurement by the X-ray diffraction method. The hexagonal layered compound contained in the oxide sintered body is a compound represented by In ₂ O ₃ (ZnO) _m .

The oxide sintered body of this embodiment may also contain a spinel structure compound represented by Zn _{2 - x} Sn _{1 - y} In _{x + y} O ₄ [0≦x<2, 0≦y<1] and a spinel structure compound represented by In ₂ O ₃ represents the bixbyite structure compound.

(Bulk resistance) When the oxide sintered body of this embodiment contains the X element, if the content ratio of the X element is within the range of the above formula (1X), the bulk resistance of the sputtering target can also be sufficiently low.

The volume resistance of the sputtering target of this embodiment is preferably 50 mΩcm or less, more preferably 25 mΩcm or less, still more preferably 10 mΩcm or less, still more preferably 5 mΩcm or less, particularly preferably 3 mΩcm or less. If the volume resistance is 50 mΩcm or less, DC sputtering can be used for stable film formation.

The volume resistance value can be measured based on the four-point probe method (JIS R 1637: 1998) using a known resistivity meter. Preferably, the measurement site is about 9 sites, and the average value of the measured 9 sites is the volume resistance value.

When the measurement part is located in the case where the planar shape of the oxide sintered body is a quadrilateral, it is preferable to divide the surface into 9 parts of 3×3, and set them as 9 central points of each quadrilateral.

Furthermore, when the planar shape of the oxide sintered body is a circle, it is preferable to divide the square inscribed with the circle into 9 parts of 3×3, and set them as 9 central points of each square.

(Average crystal grain size) From the viewpoints of preventing abnormal discharge and ease of manufacture, the average crystal grain size of the oxide sintered body of this embodiment is preferably 10 μm or less, and more preferably 8 μm or less.

If the average crystal grain size is 10 μm or less, abnormal discharge caused by the grain boundary can be prevented. The lower limit of the average crystal grain size of the oxide sintered body is not particularly defined, but it is preferably 1 μm or more from the viewpoint of ease of production.

The average crystal grain size can be adjusted by selecting raw materials and changing manufacturing conditions. Specifically, it is preferable to use a raw material with a smaller average particle diameter, and it is more preferable to use a raw material with an average particle diameter of 1 μm or less. Furthermore, during sintering, the higher the sintering temperature or the longer the sintering time, the larger the average crystal grain size tends to be.

The average crystal grain size can be measured in the following manner.

When the surface of the oxide sintered body is polished and the planar shape is a quadrilateral, the surface is divided into 16 parts of equal area, and the 16 central points of each quadrilateral are measured at a magnification of 1000 times (80 μm× For the observed particle size in the 125 μm) frame, calculate the average value of the particle size in the 16 locations respectively, and finally set the average value of the 16 measured values as the average crystal particle size.

When the surface of the oxide sintered body is polished and the planar shape is a circle, the square inscribed in the circle is divided into 16 parts with equal area, and the center point of each square is measured in 16 parts. The particle size of the particles observed in the frame of 1000 times (80 μm×125 μm) is calculated, and the average of the particle size in the frame of 16 locations is calculated.

Regarding the particle size, for particles with an aspect ratio of less than 2, based on JIS R 1670: 2006, the particle size of the crystal grains is measured as the equivalent circle diameter. As a measurement procedure of the equivalent circle diameter, specifically, a compass is used to measure the measurement target crystal grains of the microstructure photograph and read the diameter corresponding to the area of the target crystal grain. For particles with an aspect ratio of 2 or more, the average value of the longest diameter and the shortest diameter is taken as the particle diameter of the particle. The crystal grains can be observed by scanning electron microscope (SEM). The hexagonal layered compound, spinel compound and bixbyite structure compound can be confirmed by the method described in the following examples.

When the oxide sintered body of this embodiment contains hexagonal layered compound and spinel compound, the difference between the average crystal grain size of the hexagonal layered compound and the average crystal grain size of the spinel compound is preferably 1 Below μm. By setting the average crystal grain size in this range, the strength of the oxide sintered body can be improved.

More preferably, the oxide sintered body of the present embodiment has an average crystal grain size of 10 μm or less, and the difference between the average crystal grain size of the hexagonal layered compound and the spinel compound is 1 μm or less.

In addition, when the oxide sintered body of this embodiment contains the bixbyite structure compound and the spinel compound, it is preferable that the average crystal grain size of the bixbyite structure compound and the average crystal grain size of the spinel compound The difference is 1 μm or less. By setting the average crystal grain size in this range, the strength of the oxide sintered body can be improved.

More preferably, the average crystal grain size of the oxide sintered body of this embodiment is 10 μm or less, and the difference between the average crystal grain size of the bixbyite structure compound and the average crystal grain size of the spinel compound is 1 μm or less.

(Relative density) The relative density of the oxide sintered body of this embodiment is preferably 95% or more, more preferably 96% or more.

If the relative density of the oxide sintered body of this embodiment is 95% or more, the sputtering target of this embodiment has high mechanical strength and excellent conductivity. Therefore, it is possible to further improve the plasma discharge when the sputtering target material of this embodiment is installed in an RF (radio frequency, radio frequency) magnetron sputtering device or a DC (direct current, direct current) magnetron sputtering device for sputtering. The stability. The relative density of the oxide sintered body is expressed as a percentage of the actual measured density of the oxide sintered body relative to the theoretical density calculated based on the inherent density of each oxide in the sintered body and the composition ratios. The relative density of the oxide sintered body is calculated based on the inherent density of each of indium oxide, zinc oxide, tin oxide, and the oxide of the X element contained as required, and the composition ratio of the oxide relative to the theoretical density. The actual measured density of the body is expressed as a percentage.

The relative density of the oxide sintered body can be measured based on the Archimedes method. The relative density (unit: %) is specifically calculated by dividing the air weight of the oxide sintered body by the volume (= the weight of the sintered body in water/the specific gravity of water at the measurement temperature), and set it as relative based on the following formula (number 5) Value in percentage of theoretical density ρ(g/cm ³ ). Relative density={(air weight/volume of oxide sintered body)/theoretical density ρ}×100 ρ=(C ₁ /100/ρ ₁ ＋C ₂ /100/ρ _{2 …} ＋C _n /100/ρ _n ) ^-1 (Number 5)

Furthermore, in the formula (numeral 5), C ₁ to C _n represent the content (mass%) of the oxide sintered body or the constituent material of the oxide sintered body, respectively, and ρ ₁ to ρ _n represent corresponding to C ₁ to C _n The density of each constituent material (g/cm ³ ).

Furthermore, since the density and the specific gravity are approximately the same, the density of each constituent substance can be calculated using the value of the specific gravity of the oxide described in the Chemical Handbook, Basic Edition I, The Chemical Society of Japan, Revised 2 Edition (Maruzen Co., Ltd.).

[Method for manufacturing oxide sintered body] The manufacturing method of the oxide sintered body of this embodiment includes mixing, pulverization, granulation, molding, and sintering. The manufacturing method of the oxide sintered body may also include other steps. As other steps, an annealing step can be cited.

Hereinafter, the case of manufacturing an ITZO-based oxide sintered body is taken as an example, and each step is specifically described.

The oxide sintered body of this embodiment can pass through the mixing and pulverizing step of mixing and pulverizing the indium raw material, the zinc raw material, the tin raw material and the X element raw material, the granulating step of granulating the raw material mixture, the forming step of forming, and the forming step It is produced by the sintering step of sintering and the annealing step of annealing the sintered body as needed.

(1) Mixing and crushing steps The mixing and pulverizing step is a step of mixing and pulverizing the raw materials of the oxide sintered body to obtain a raw material mixture. The raw material mixture is preferably powdered, for example.

In the mixing and pulverization steps, first, the raw materials of the oxide sintered body are prepared.

In the case of manufacturing an oxide sintered body containing In, Zn, and Sn, the raw materials are as follows.

The indium raw material (In raw material) is not particularly limited as long as it is a compound or metal containing In.

The zinc raw material (Zn raw material) is not particularly limited as long as it is a compound or metal containing Zn.

The tin raw material (Sn raw material) is not particularly limited as long as it is a compound or metal containing Sn.

In the case of producing a sintered oxide containing X element, the raw materials are as follows.

The raw material of X element is not particularly limited as long as it is a compound or metal containing X element.

In raw materials, Zn raw materials, Sn raw materials, and X element raw materials are preferably oxides.

Raw materials such as indium oxide, zinc oxide, tin oxide, and element X oxides are preferably of high purity. The purity of the raw material of the oxide sintered body is preferably 99% by mass or more, more preferably 99.9% by mass or more, and still more preferably 99.99% by mass or more. If a high-purity raw material is used, a densely structured sintered body is obtained, and the volume resistivity of the sputtering target material including the sintered body becomes low.

The average particle diameter of the primary particles of the metal oxide as a raw material is preferably 0.01 μm or more and 10 μm or less, more preferably 0.05 μm or more and 5 μm or less, and still more preferably 0.1 μm or more and 5 μm or less.

If the average particle size of the primary particles of the metal oxide used as the raw material is 0.01 μm or more, it is difficult to aggregate, and if the average particle size is 10 μm or less, the mixing ability is sufficient, and a sintered body with a dense structure is obtained. The average particle diameter was measured with a laser diffraction particle size distribution measuring device SALD-300V (manufactured by Shimadzu Corporation) using a median particle diameter D50.

To the raw material of the oxide sintered body, a dispersant used to deagglomerate and a thickener used to adjust the viscosity to be suitable for granulation using a spray dryer are added, and mixed and crushed by a bead mill or the like. As the dispersant, for example, acrylic acid methacrylic acid copolymer ammonia neutralized product and the like can be cited, and as the thickener, for example, polyvinyl alcohol and the like can be cited.

(2) Calcining treatment steps The raw material mixture obtained in the mixing and crushing steps can be directly granulated, but it can also be calcined before granulation. The calcination treatment generally sinters the raw material mixture at 700°C or higher and 900°C or lower for 1 hour or more and 5 hours or less.

(3) Granulation steps The granulation treatment of the raw material mixture without calcination treatment or the raw material mixture subjected to calcination treatment can improve the fluidity and filling property in the forming step of (4) below.

In this specification, the step of granulating the raw material of the oxide sintered body to obtain raw material granulated powder is sometimes referred to as the granulating step.

The granulation treatment can be performed using a spray dryer or the like. In order for the granulated powder obtained in the granulation step to be uniformly filled in the mold in the forming step, it is preferably a true spherical shape.

The granulation conditions are appropriately selected by adjusting the concentration of the introduced raw material slurry, the number of revolutions of the spray dryer, and the temperature of the hot air.

Regarding the preparation of the slurry solution, when using a raw material mixture that has not been calcined, the slurry solution obtained in the mixing and pulverizing step is used directly, and when using a raw material mixture that has been calcined, it is mixed again , Crushing step, prepare into slurry solution before use.

In the method of manufacturing the oxide sintered body of this embodiment, the particle size of the raw material granulated powder formed by the granulation treatment is controlled to be in the range of 25 μm or more and 150 μm or less.

If the particle size of the raw material granulated powder is 25 μm or more, the sliding property of the raw material granulated powder relative to the surface of the mold used in the molding step (4) below is improved, and the raw material granulated powder can be fully filled in Inside the mold.

If the particle size of the raw material granulated powder is 150 μm or less, it can suppress that the particle size is too large and the filling rate in the mold becomes low.

The particle size of the raw material granulated powder is preferably 25 μm or more and 75 μm or less.

The method for obtaining raw material granulated powder with a particle size in a specific range is not particularly limited. For example, the following method can be cited: the raw material mixture (raw material granulated powder) subjected to the granulation treatment is put into a sieve, and the raw material granulated powder belonging to the desired particle size range is selected. The sieve used in this method is preferably a sieve having an opening of a size through which the raw material granulated powder of the desired particle size can pass. Preferably, a first screen and a second screen are used. The first screen is used to screen the raw material granulated powder based on the lower limit of the particle size range, and the second screen is used to screen the granulated powder above the particle size range. The limit is the basis for screening raw granulated powder. For example, when the particle size of the raw material granulated powder is controlled to be within the range of 25 μm or more and 150 μm or less, first, use the raw material granulated powder with less than 25 μm that can pass but not make the raw material of 25 μm or more. The sieve (the first sieve) at the opening of the size through which the powder passes, screens the raw material granulated powder with a particle size of 25 μm or more. Secondly, for the raw granulated powder after sieving, use a sieve (second sieve) with an opening of the size that the raw granulated powder of 150 μm or less can pass but does not allow the raw granulated powder of more than 150 μm to pass through. , Screen raw material granulated powder within the range of 25 μm above 150 μm. It is also possible to use the second screen first, and then use the first screen second.

The method of controlling the particle size range of the raw material granulated powder is not limited to the above-mentioned method using a screen, as long as the raw material granulated powder used in the forming step of the following (4) is within the range of 25 μm or more and 150 μm or less. can.

Furthermore, in the raw material mixture subjected to the calcination treatment, since the particles are combined with each other, in the case of granulation treatment, it is preferable to perform the pulverization treatment before the granulation treatment.

(4) Forming steps In this specification, the step of filling the raw material granulated powder obtained in the granulation step into a mold, and molding the raw material granulated powder filled in the mold to obtain a molded body is sometimes referred to as a forming step.

As the forming method in the forming step, for example, die press forming can be cited.

As the sputtering target material, in the case of obtaining a sintered body with a higher sintered density, it is preferable to perform pre-forming by pressure forming by a mold in the forming step, and then by cold isostatic pressing (CIP; Cold Isostatic Pressing ) Forming, etc. and then compacting.

The particle size of the raw material granulated powder is preferably 25 μm or more and 150 μm or less, and more preferably 25 μm or more and 75 μm or less.

If the particle size of the raw material granulated powder is 25 μm or more and 150 μm or less, the raw material granulated powder can be sufficiently filled in the mold used in the molding step, and therefore, the density unevenness in the molded body can be reduced.

(5) Sintering step In this specification, the step of sintering the formed body obtained in the forming step in a specific temperature range is sometimes referred to as the sintering step.

In the sintering step, normal sintering methods such as normal pressure sintering, hot pressing sintering, or hot isostatic pressing (HIP; Hot Isostatic Pressing) sintering can be used.

The sintering temperature is preferably from 1310°C to 1440°C, more preferably from 1320°C to 1430°C.

If the sintering temperature is 1310°C or more and 1440°C or less, it is easy to control the average value (H _av ) of the Vickers hardness on the surface of the oxide sintered body within the above range. That is, by using the raw material granulated powder having a particle size within a specific range obtained in the granulation step to produce a compact, and sintering the compact at a specific temperature, the uneven strength in the oxide sintered compact can be reduced. It can also prevent the Vickers hardness from being too large.

If the sintering temperature is above 1310°C, a sufficient sintering density can be obtained, and the bulk resistance of the sputtering target can also be lowered.

If the sintering temperature is below 1440°C, the sublimation of zinc oxide during sintering can be suppressed.

In the sintering step, it is preferable to set the temperature increase rate from room temperature to the sintering temperature to be 0.1°C/min or more and 3°C/min or less.

In addition, during the heating process, the temperature may be maintained at 700° C. or higher and 800° C. or lower for 1 hour or more and 10 hours or lower, and after holding at a specific temperature for a specific time, the temperature may be increased to the sintering temperature.

The sintering time varies depending on the sintering temperature, but it is preferably 1 hour or more and 50 hours or less, more preferably 2 hours or more and 30 hours or less, and still more preferably 3 hours or more and 20 hours or less.

As the environment during sintering, for example, an environment containing air or oxygen, an environment containing air or oxygen and a reducing gas, or an environment containing air or oxygen and an inert gas can be cited. Examples of the reducing gas include hydrogen, methane gas, and carbon monoxide gas. As the inert gas, for example, argon gas, nitrogen gas, and the like can be cited.

(6) Annealing step In the manufacturing method of the oxide sintered body of this embodiment, the annealing step is not necessary. In the case of performing the annealing step, generally, the temperature is maintained at 700°C or more and 1100°C or less for 1 hour or more and 5 hours or less.

In the annealing step, the sintered body may be temporarily cooled, and then heated and annealed again, or annealing may be performed when the sintering temperature is lowered.

As the environment during annealing, for example, an environment containing air or oxygen, an environment containing air or oxygen and a reducing gas, or an environment containing air or oxygen and an inert gas can be cited. Examples of the reducing gas include hydrogen, methane gas, and carbon monoxide gas. As the inert gas, for example, argon gas, nitrogen gas, and the like can be cited.

Furthermore, in the case of manufacturing an oxide sintered body of a system different from that of ITZO, it can also be manufactured by the same steps as above.

[Manufacturing method of sputtering target] The sputtering target material can be manufactured by cutting the oxide sintered body obtained by the above-mentioned manufacturing method into an appropriate shape, and polishing the surface of the oxide sintered body as necessary.

Specifically, by cutting the oxide sintered body into a shape suitable for installation in a sputtering device, a sputtering target material (sometimes referred to as a target material) is obtained. By adhering the target material to the backing plate, a sputtering target is obtained.

When an oxide sintered body is used as a target material, the surface roughness Ra of the sintered body is preferably 0.5 μm or less. As a method of adjusting the surface roughness Ra of the sintered body, for example, a method of grinding the sintered body with a flat grinding disk can be cited.

The surface of the sputtering target material is preferably finished with diamond grindstones of No. 100 to 1,000, and particularly preferably processed by diamond grindstones of No. 400 to 800. By using diamond grindstones of size 100 or more or 1,000 or less, the sputtering target material can be prevented from breaking.

Preferably, the surface roughness Ra of the sputtering target material is 0.5 μm or less and has a non-directional grinding surface. If the surface roughness Ra of the sputtering target material is 0.5 μm or less and has a non-directional polishing surface, abnormal discharge and particle generation can be prevented.

Finally, the sputtering target material obtained is cleaned. As a method of cleaning treatment, for example, any method such as a blower and running water washing can be cited. When the blower is used to remove foreign matter, the foreign matter can be removed more effectively by drawing air from the dust collector from the side where the nozzle of the blower faces.

Furthermore, in addition to the above-mentioned cleaning treatment of blower or running water washing, ultrasonic washing and the like can also be further implemented. As an ultrasonic cleaning method, it is more effective to perform multiple vibrations at a frequency between 25 kHz and 300 kHz. For example, it is preferable to perform ultrasonic cleaning by multiple vibrations at 12 frequencies every 25 kHz between 25 kHz and 300 kHz.

The thickness of the sputtering target material is usually 2 mm or more and 20 mm or less, preferably 3 mm or more and 12 mm or less, more preferably 4 mm or more and 9 mm or less, and more preferably 4 mm or more and 6 mm or less.

The sputtering target material can be manufactured by joining the sputtering target material obtained through the above steps and processing to the backing plate. In addition, a plurality of sputtering target materials may be attached to one backing plate to substantially manufacture one sputtering target (multi-divided sputtering target).

The sputtering target of this embodiment includes an oxide sintered body, and the average value (H _av ) of the Vickers hardness on the surface of the oxide sintered body exceeds 500 Hv and does not reach 900 Hv, so it is a spatter with improved crack resistance Plating target.

If the sputtering target material of this embodiment is used for sputtering film formation, the crack resistance is improved, and therefore the oxide semiconductor thin film can be produced stably. Example

Hereinafter, the present invention will be specifically explained based on examples. The present invention is not limited to the examples.

Manufacture sputtering targets including ITZO series oxide sintered bodies.

(Example 1) First, as a raw material, the following powders are weighed so as to have an atomic ratio (In: 25 atomic %, Sn: 15 atomic %, Zn: 60 atomic %). ・In raw material: indium oxide powder with a purity of 99.99% by mass (Average particle size: 0.3 μm) ・Sn raw material: tin oxide powder with a purity of 99.99% by mass (Average particle size: 1.0 μm) ・Zn raw material: zinc oxide powder with a purity of 99.99% by mass (Average particle size: 3.0 μm)

The average particle diameter of the above-mentioned oxide powder used as a raw material is a median particle diameter D50, and the average particle diameter is measured by a laser diffraction particle size distribution analyzer SALD-300V (manufactured by Shimadzu Corporation).

Secondly, add acrylic acid methacrylic acid copolymer ammonia neutralizer (manufactured by Sanming Chemical Co., Ltd., Bangster X754B) as a dispersant, polyvinyl alcohol as a thickener, and water to these raw materials, and mix them with a bead mill It was pulverized for 2 hours to obtain a slurry solution for granulation with a solid content concentration of 70% by mass. The obtained slurry solution was supplied to a spray dryer, rotated at a speed of 12,000, and granulated under the condition of a hot air temperature of 150°C to obtain raw material granulated powder.

By passing the raw material granulated powder through a 200-mesh sieve, the granulated powder with a particle size exceeding 75 μm is removed, and then by passing through a 500-mesh sieve, the granulated powder less than 25 μm is removed to remove the raw material The particle size of the granulated powder is adjusted within the range of 25 μm or more and 75 μm or less.

5 shows the SEM observation image of the raw granulated powder prepared in Example 1.

Next, the raw material granulated powder is uniformly filled into a mold with an inner diameter of 300 mm × 600 mm × 9 mm, and the cold press is used for pressure forming. After pressure forming, the cold equalizing pressure device (CIP device) is used for forming at a pressure of 294 MPa to obtain a molded body.

The three molded bodies thus obtained were heated to 780°C in an oxygen atmosphere in a sintering furnace, and then kept at 780°C for 5 hours, and then heated to 1325°C, and kept at the sintering temperature (1325°C) for 20 hours, and then furnaced It is internally cooled to obtain an oxide sintered body. Furthermore, it is carried out at a heating rate of 2°C/min.

Three pieces of the obtained oxide sintered body were cut separately, and plane grinding was performed to obtain three pieces of oxide sintered body plates of 142 mm×305 mm×5 mmt. One of them was used for characteristic evaluation, and two were used for G1 target [142 mm×610 mm (divided into two parts)×5 mmt].

The plane grinding system uses a plane grinding device. First, use #100 diamond grindstone to grind the oxide sintered body plate, and then use #200→#400→#800 diamond grindstones with finer grain sizes to grind sequentially Processing.

Observation of the sintered oxide sintered plate after grinding with an optical microscope revealed no particular microcracks.

Using one of the three obtained oxide sintered compact plates, first, after measuring the Vickers hardness, they were appropriately cut into specific sizes and various measurements were performed.

(1) Determination of Vickers hardness The measurement of the Vickers hardness is carried out using a Hardness Tester (AKASHI MVK-E3) according to JIS Z 2244:2009. The measurement points are based on the data of 10 points every 30 mm from the end of one side on the center line of the oxide sintered body (142×305 mm size), and the average value is used for evaluation.

(2) Confirmation of crystal structure The oxide sintered body plate that has been tested for Vickers hardness was cut out for X-ray diffraction measurement, and the crystal structure was investigated under the following conditions using an X-ray diffraction measurement device (XRD). As a result, in the oxide sintered body of Example 1, it was confirmed that the hexagonal layered compound represented by In ₂ O ₃ (ZnO) _m (where m = an integer from 2 to 7) and the Zn _{2 - x} Sn _{1 - y} In _{x + y} O ₄ [0≦x<2, 0≦y<1] represents a spinel compound. FIG. 6 shows the XRD pattern of the oxide sintered body of Example 1. FIG.・Device: Smartlab manufactured by RIGAKU Co., Ltd. ・X-ray: Cu-Kα rays (wavelength 1.5418×10 ^-10 m) ・Parallel beam, 2θ-θ reflection method, continuous scanning (2.0°/min) ・Sampling interval: 0.02°・Divergence Slit (DS): 1.0 mm ・Scattering Slit (SS): 1.0 mm ・Receiving Slit (RS): 1.0 mm

(3) Confirmation of composition Similarly, the remaining oxide sintered body plate was used to analyze the atomic ratio of the oxide sintered body with an inductively coupled plasma emission spectrometer (ICP-AES, manufactured by Shimadzu Corporation). The results are as follows. Zn/(In＋Sn＋Zn)=0.60 Sn/(Sn＋Zn)=0.20 In/(In＋Sn＋Zn)=0.25

(Examples 2～5) The oxide sintered bodies of Examples 2 to 5 were produced in the same manner as in Example 1, except that the sintering temperature in Example 1 was changed to the sintering temperature described in Table 1.

(Comparative Examples 1～2) The oxide sintered bodies of Comparative Examples 1 and 2 were produced in the same manner as in Example 1, except that the sintering temperature in Example 1 was changed to the sintering temperature described in Table 1.

The oxide sintered body of Comparative Example 2 was observed with an optical microscope after grinding, and as a result, microcracks were confirmed.

(Comparative Examples 3～4) The oxide sintered bodies of Comparative Examples 3 to 4 are the same as those of Example 1 except that the raw material in Example 1 is not granulated but formed by a mold, and the sintering temperature is changed to the sintering temperature described in Table 1. Manufactured in the same way.

(Comparative Examples 5-6) The oxide sintered bodies of Comparative Examples 5 to 6 were produced in the same manner as in Example 1, except that the sintering temperature in Example 1 was changed to the sintering temperature described in Table 1.

[Table 1] Raw material granulated powder (μm) Sintering temperature Crystal structure compound in sintered body Vickers hardness (Hv) micro- Crack resistance (℃) average value Minimum Max Cracked (kW) Example 1 25~75 1325 Zn ₂ SnO ₄ +In ₂ O ₃ (ZnO) ₄ 543 521 560 no 2.25 Example 2 25~75 1350 Zn ₂ SnO ₄ +In ₂ O ₃ (ZnO) ₄ 645 628 669 no 2.50 Example 3 25~75 1375 Zn ₂ SnO ₄ +In ₂ O ₃ (ZnO) ₄ 722 709 745 no 2.50 Example 4 25~75 1400 Zn ₂ SnO ₄ +In ₂ O ₃ (ZnO) ₄ 783 759 798 no 2.25 Example 5 25~75 1425 Zn ₂ SnO ₄ +In ₂ O ₃ (ZnO) ₄ 864 844 880 no 2.00 Comparative example 1 25~75 1300 Zn ₂ SnO ₄ +In ₂ O ₃ (ZnO) ₄ 401 389 430 no 1.50 Comparative example 2 25~75 1450 Zn ₂ SnO ₄ +In ₂ O ₃ (ZnO) ₄ 969 950 991 no 1.75 Comparative example 3 - 1375 Zn ₂ SnO ₄ +In ₂ O ₃ (ZnO) ₄ 439 415 458 no 1.50 Comparative example 4 - 1400 Zn ₂ SnO ₄ +In ₂ O ₃ (ZnO) ₄ 443 426 459 no 1.50 Comparative example 5 25~75 1309 Zn ₂ SnO ₄ +In ₂ O ₃ (ZnO) ₄ 481 460 500 no 1.50 Comparative example 6 25~75 1442 Zn ₂ SnO ₄ +In ₂ O ₃ (ZnO) ₄ 914 900 935 Have 1.75

(Manufacturing of sputtering targets) Next, by using two oxide sintered body plates of Examples 1 to 5 and Comparative Examples 1 to 6 and joining them to the backing plate, the G1 size: 142 mm×610 mm (divided into two parts)×5 mmt sputtering target.

Among all targets, the bonding rate is over 98%. When the oxide sintered body was joined to the backing plate, no cracks were generated in the oxide sintered body, and the sputtering target material could be manufactured well. The bonding rate was confirmed by X-ray CT.

(Crack resistance during sputtering) Using the sputtering target that has been produced, using the G1 sputtering device, pre-sputtering is performed for 1 hour under the conditions of 100% Ar atmosphere and 1 kW sputtering power. Here, the so-called G1 sputtering device refers to the first generation sputtering device for mass production with a substrate size of about 300 mm×400 mm. After pre-sputtering, use the film forming conditions shown in Table 2 to change the power to perform continuous discharge for 2 hours. After the discharge is completed, open the chamber to visually confirm the presence of cracks, increase the power, and repeat the discharge test again to evaluate Crack resistance.

The crack resistance is the maximum sputtering power at which the sputtering target does not break. The case where the crack resistance is 1.80 kW or more is regarded as qualified. Table 1 shows the evaluation results of the crack resistance of each sputtering target.

[Table 2] Continuous discharge test conditions Ambient gas Ar+O ₂ Back pressure before film formation (Pa) 2 × 10 ^{- 4} Sputtering pressure during film formation (Pa) 0.5 Oxygen partial pressure during film formation (%) 20

According to the sputtering target materials using the oxide sintered bodies of Examples 1 to 5, it can be seen that the crack resistance is excellent. It is believed that this is due to the high Vickers hardness of the surface of the oxide sintered body.

It can be seen that the sputtering target materials using the oxide sintered bodies of Comparative Examples 1, 3, and 4 did not produce microcracks during grinding and polishing, but the crack resistance during sputtering was inferior to those of Examples 1 to 5. It is considered that the reason is that the Vickers hardness of the surface of the oxide sintered bodies of Comparative Examples 1, 3, and 4 is low.

It can be seen that the sputtering target material using the oxide sintered body of Comparative Example 5 did not produce microcracks during grinding and polishing, but the crack resistance during sputtering was inferior to those of Examples 1 to 5. It is considered that the reason is that the Vickers hardness of the surface of the oxide sintered body of Comparative Example 5 is low.

Regarding the oxide sintered body of Comparative Example 6, the oxide sintered body after grinding was observed with an optical microscope, and as a result, microcracks were confirmed.

1: Plate-shaped oxide sintered body 1A: Cylindrical oxide sintered body 1B: Round oxide sintered body 1C: Divided into multiple oxide sintered bodies 3: Backing board

Fig. 1 is a perspective view showing the shape of a target in one embodiment of the present invention. Fig. 2 is a perspective view showing the shape of a target in one embodiment of the present invention. Fig. 3 is a perspective view showing the shape of a target in one embodiment of the present invention. Fig. 4 is a perspective view showing the shape of a target in one embodiment of the present invention. Fig. 5 is an SEM (scanning electron microscope) observation image of the raw granulated powder prepared in the embodiment. Fig. 6 is an XRD (X ray diffraction) diagram of the oxide sintered body of the embodiment.

1: Plate-shaped oxide sintered body

Claims (8)

An oxide sintered body, The average value of the Vickers hardness of the surface of the oxide sintered body exceeds 500 Hv and does not reach 900 Hv. A sputtering target material comprising the oxide sintered body as claimed in claim 1. Such as the sputtering target of claim 2, where The oxide sintered body contains indium element, tin element, and zinc element. Such as the sputtering target of claim 3, where The oxide sintered body further contains X element, The X element is selected from at least one element selected from the group consisting of germanium element, silicon element, yttrium element, zirconium element, aluminum element, magnesium element, ytterbium element and gallium element. Such as the sputtering target of claim 3, where The above-mentioned oxide sintered body satisfies the range of the atomic composition ratio represented by the following formulas (1), (2) and (3), 0.40≦Zn/(In＋Sn＋Zn)≦0.80 (1) 0.15≦Sn/(Sn＋Zn)≦0.40 (2) 0.10≦In/(In＋Sn＋Zn)≦0.35 (3). The sputtering target material according to any one of claims 2 to 5, wherein the oxide sintered body includes a hexagonal layered compound represented by In ₂ O ₃ (ZnO)m [m=2-7] and a layered compound represented by Zn _{2 -x} Sn _1-y In _x+y O ₄ [0≦x<2, 0≦y<1] represents a spinel structure compound. A method for manufacturing a sputtering target, which is used to manufacture the sputtering target of any one of claims 2 to 6, and includes the following steps: Granulate the raw material of the above-mentioned oxide sintered body to obtain raw material granulated powder with a particle size of 25 μm or more and 150 μm or less; Filling the raw material granulated powder into a mold, and molding the raw material granulated powder filled in the mold to obtain a molded body; and The above-mentioned molded body is sintered at 1310°C or higher and 1440°C or lower. Such as the manufacturing method of sputtering target material of claim 7, wherein The particle size of the raw material granulated powder is 25 μm or more and 75 μm or less.

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