TWI669283B - Oxide sintered body and sputtering target material and their manufacturing method - Google Patents

Abstract

An oxide sintered body containing 50 ppm to 500 ppm of zirconium, and the ratio (atomic%) of the contents of zinc, indium, gallium, and tin to all metal elements except oxygen is set to [Zn], [ For In], [Ga], and [Sn], the following formula (1) to formula (3) are satisfied: 35 atom% ≦ [Zn] ≦ 55 atom% (1) 20 atom% ≦ ([In] ＋ [Ga]) ≦ 55 atomic% (2) 5 atomic% ≦ [Sn] ≦ 25 atomic% (3).

Description

Oxide sintered body and sputtering target material and their manufacturing method

The present invention relates to a thin film transistor (TFT) oxide semiconductor thin film used in a display device such as a liquid crystal display or an organic electroluminescence (EL) display formed by a sputtering method The oxide sintered body and the sputtering target used at the time and their manufacturing method.

Compared with general-purpose amorphous silicon (a-Si), the amorphous (amorphous) oxide semiconductor thin film used in TFT has high carrier mobility, large optical band gap, and Film formation at low temperature. Therefore, it is expected to be used in next-generation displays that are large in size, high resolution, and require high-speed driving, and applied to resin substrates with low heat resistance. As an oxide semiconductor suitable for these applications, an amorphous oxide semiconductor containing In has been proposed. For example, In-Ga-Zn oxide semiconductors have attracted attention.

When forming the oxide semiconductor thin film, a sputtering method for sputtering a sputtering target (hereinafter sometimes referred to as a "target") is suitably used, and the sputtering target includes the same composition as the thin film s material.

In Patent Document 1, as a composite oxide sintered body having good TFT characteristics, it is described that it contains a group selected from In, Zn, Sn, and X (Mg, Al, Ga, Si, Sc, Ti, Y, Zr, One or more elements X of Hf, Ta, La, Nd, and Sm) include a sputter target of a bixbyite structure compound represented by In ₂ O ₃ and a spinel stone structure compound.

In Patent Document 2, an In-Ga-Zn oxide sintered body that can be sputtered stably is described as characterized by InGaZn _m O _{3 + m} (m is an integer of 0.5 or more), and An oxide sintered body having an average particle diameter of the source phase and the HfO ₂ phase or ZrO ₂ phase of 10 μm or less.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2014-111818

[Patent Document 2] Japanese Patent Laid-Open No. 2015-189632

The sputtering target is used in a state where the oxide sintered body is welded to the bottom plate. In the step of welding the oxide sintered body to the bottom plate, the oxide sintered body may crack.

The production requirements of display devices are always efficient. Furthermore, in consideration of productivity, manufacturing cost, etc., of course, it is necessary to suppress the sputtering target during the sputtering target material used for the manufacture of the oxide semiconductor thin film for display devices and the oxide sintered body as its raw material during sputtering The target material is cracked, and it is required to suppress the cracking of the oxide sintered body when the oxide sintered body is welded to the base plate.

The embodiment of the present invention was made in view of the above facts, and the first object is to provide an oxide sintered body suitable for producing In-Ga-Zn-Sn-based oxygen The In-Ga-Zn-Sn-based oxide sintered body used for the sputtering target of the compound semiconductor thin film can suppress the occurrence of cracks when soldered to the substrate.

A second object of an embodiment of the present invention is to provide a method for manufacturing the oxide sintered body.

The third object of the embodiment of the present invention is to provide a sputtering target using the oxide sintered body.

The fourth object of the embodiment of the present invention is to provide a method for manufacturing a sputtering target.

In order to solve the above problems, the inventors repeatedly conducted intensive research, and found that the oxide sintered body containing oxides of zinc, indium, gallium, and tin contains zirconium in a specific range, thereby solving the above problems To complete the embodiments of the present invention.

The first embodiment of the present invention is an oxide sintered body containing 50 ppm to 500 ppm of zirconium, and the ratio (atomic%) of the contents of zinc, indium, gallium, and tin relative to all metal elements except oxygen When [Zn], [In], [Ga], and [Sn], the following formula (1) to formula (3) are satisfied: 35 atomic% ≦ [Zn] ≦ 55 atomic% ‧‧‧‧ (1)

20 atom% ≦ ([In] + [Ga]) ≦ 55 atom% ‧‧‧‧ (2)

5 atomic% ≦ [Sn] ≦ 25 atomic% ‧‧‧‧ (3)

The relative density of the oxide sintered body is preferably 95% or more.

It is preferable that the maximum circular equivalent diameter of the pores in the oxide sintered body is 3 μm or less.

It is preferable that the relative ratio of the average circle equivalent diameter of the pores in the oxide sintered body to the maximum circle equivalent diameter is 0.3 or more and 1.0 or less.

The average crystal grain size of the oxide sintered body is preferably 20 μm or less.

It is preferable that the area ratio of crystal grains with an oxide sintered body having a crystal grain size exceeding 30 μm is 10% or less.

The specific resistance of the oxide sintered body is preferably 1 Ω‧cm or less.

The second embodiment of the present invention is a sputtering target material obtained by fixing the oxide sintered body of the first embodiment to a base plate by a welding material.

A third embodiment of the present invention is a method of manufacturing the oxide sintered body of the first embodiment, which includes the step of preparing a mixed powder containing zinc oxide, indium oxide, gallium oxide, tin oxide, and zirconium oxide in a predetermined ratio Sintering the mixed powder into a predetermined shape.

The step of preparing the mixed powder includes the step of mixing the raw material powder containing zinc oxide, indium oxide, gallium oxide, and tin oxide by using a ball mill or bead mill containing a medium containing zirconia.

The step of preparing the mixed powder may include a step of mixing the raw material powder containing zinc oxide, indium oxide, gallium oxide, tin oxide and zirconium oxide by a ball mill or a bead mill instead of the above steps.

The step of sintering may also be hot pressing. That is, in the sintering step, It may also include the step of maintaining at a sintering temperature of 900 ° C to 1200 ° C for 1 hour to 12 hours in a state where a surface pressure of 10 MPa to 39 MPa is applied to the mixed powder by a forming die. Preferably, in the case of hot pressing, the average heating rate up to the sintering temperature is 600 ° C./hr or less.

The step of sintering may also be normal pressure sintering. In the normal pressure sintering, a step of preforming the mixed powder is included after the step of preparing the mixed powder and before the step of sintering. In addition, the sintering step also includes a step of holding the preformed molded body at normal pressure and a sintering temperature of 1450 ° C to 1600 ° C for 1 hour to 5 hours. Preferably, in the case of normal pressure sintering, the average heating rate up to the sintering temperature is 100 ° C./hr or less.

A fourth embodiment of the present invention is a method for manufacturing a sputtering target material according to a second embodiment, which includes welding the oxide to the oxide sintered body of the first embodiment or by the manufacturing method of the third embodiment The step of bonding the manufactured oxide sintered body to the bottom plate.

The embodiment of the present invention can provide an oxide sintered body capable of suppressing cracks when welding to a base plate, a sputtering target using the oxide sintered body, and a method of manufacturing the oxide sintered body and the sputtering target .

1‧‧‧Sputtering target

10‧‧‧ oxide sintered body

20‧‧‧Bottom plate

23‧‧‧welded surface

30‧‧‧welding materials

FIG. 1 is a schematic cross-sectional view of a sputtering target according to an embodiment of the present invention.

Fig. 2 is a secondary electron image of an oxide sintered body.

<Oxide sintered body>

First, the oxide sintered body according to the embodiment of the present invention will be described in detail.

The oxide sintered body of the embodiment of the present invention contains oxides of zinc, indium, gallium, and tin. Here, in order to produce a sputtering target material that can form an oxide semiconductor thin film having excellent TFT characteristics, it is necessary to appropriately control the content of metal elements contained in the oxide sintered body used in the sputtering target material.

Therefore, the oxide sintered body of the embodiment of the present invention contains 50 ppm to 500 ppm of zirconium, and the content of zinc, indium, gallium, and tin contained in the oxide sintered body with respect to all metal elements except oxygen When (atomic%) is set to [Zn], [In], [Ga], and [Sn], the following formula (1) to formula (3) are satisfied.

35 atomic% ≦ [Zn] ≦ 55 atomic% ‧‧‧‧ (1)

20 atom% ≦ ([In] + [Ga]) ≦ 55 atom% ‧‧‧‧ (2)

5 atomic% ≦ [Sn] ≦ 25 atomic% ‧‧‧‧ (3)

"All metal elements other than oxygen contained in the oxide sintered body" are zinc, indium, gallium, tin, zirconium, and may further contain metal impurities that are inevitable in production.

Here, since zirconium and unavoidable metal impurities are trace amounts, the influence on the ratio of the metal element in the oxide sintered body is small. Therefore, "all metal elements other than oxygen contained in the oxide sintered body" are essentially zinc, indium, gallium, and tin.

Therefore, in this specification, the number of atoms in the oxide sintered body is expressed For the content of zinc, indium, gallium and tin, the content rate of zinc can be changed to "[Zn]" and the content rate of indium to "[In]" relative to the total amount (total number of atoms) The content rate of gallium was changed to "[Ga]", and the content rate of tin was changed to "[Sn]". Furthermore, it becomes [Zn] + [In] + [Ga] + [Sn] = 100 atomic%. The content ratio (atomic%) of each element of zinc, indium, gallium, and tin specified as described above ([Zn], [In], [Ga], and [Sn]) satisfies the above formula (1) to formula (3) Control the content of each element.

The content rate (atomic%) of each element of zinc, indium, gallium, and tin will be described in detail below. In addition, the content of each element is mainly set in consideration of the characteristics of the oxide semiconductor thin film formed using the sputtering target.

Zinc content rate: 35 atomic% ≦ [Zn] ≦ 55 atomic%

Zinc improves the stability of the amorphous structure of the oxide semiconductor thin film. The content rate of zinc is preferably 37 atom% ≦ [Zn] ≦ 54 atom%, more preferably 40 atom% ≦ [Zn] ≦ 53 atom%.

Indium and gallium content rate: 20 atomic% ≦ ([In] + [Ga]) ≦ 55 atomic%

Indium increases the carrier mobility of the oxide semiconductor thin film.

Gallium improves the reliability of the oxide semiconductor thin film against light stress, that is, the deviation of the threshold deviation.

Indium and gallium are both group III elements and interact in imparting these characteristics. Therefore, in order to properly exert various characteristics of indium and gallium, it is desirable to appropriately control the total amount of them. The total content rate of indium and gallium is preferably 25 atom% ≦ ([In] + [Ga]) ≦ 54 atom%, more preferably 30 atom% ≦ ([In] + [Ga]) ≦ 53 atom%.

Tin content rate: 5 atomic% ≦ [Sn] ≦ 25 atomic%

Tin improves the resistance of the oxide semiconductor thin film to the etchant. The content rate of tin is preferably 7 atom% ≦ [Sn] ≦ 22 atom%, more preferably 9 atom% ≦ [Sn] ≦ 20 atom%.

In the oxide sintered body of the embodiment of the present invention, from the viewpoint of both the physical property control of the oxide sintered body and the physical property control of the oxide semiconductor thin film, the content of zirconium is controlled to 50 ppm to 500 ppm.

By adding zirconium to the oxide sintered body, the relative density of the oxide sintered body increases, and the strength of the oxide sintered body increases. When the oxide sintered body is welded to the base plate, the oxide sintered body is subjected to stress caused by impact, thermal history, etc. However, the strength of the oxide sintered body can be improved by containing zirconium, so the oxide sintered body can be suppressed rupture.

By setting the amount of zirconium to 50 ppm or more, the effect of suppressing cracking can be fully exhibited. The amount of zirconium is preferably 60 ppm or more, and more preferably 70 ppm or more.

On the other hand, zirconium exists as zirconia (zircon) in the oxide sintered body. Zirconia is an insulator, so it can cause abnormal discharge during sputtering. In addition, if an oxide sintered body containing a large amount of zirconia is used for film formation, the carrier characteristics are reduced due to zirconia in the obtained oxide semiconductor thin film. By setting the amount of zirconium to 500 ppm or less, abnormal discharge during sputtering can be suppressed, and the carrier characteristics of the oxide semiconductor thin film formed by sputtering can be maintained at a high level. The amount of zirconium is preferably 450 ppm or less, and more preferably 400 ppm or less.

The content of zirconium (amount of zirconium) in this specification is the average amount of zirconium measured by the following method.

The entire surface of the oxide sintered body is polished by 0.5 mm or more to remove black skin on the surface. Next, about 5 g of the oxide sintered body was taken, and quantitative analysis was performed by the inductively coupled plasma (Inductively Coupled Plasma, ICP) analysis method. The same measurement is performed multiple times (for example, three times). The average value of the amount of zirconium obtained is determined. In this specification, unless otherwise specified, the "zirconium amount" means the average zirconium amount.

The oxide sintered body contains oxides of zinc, indium, gallium, and tin. Specifically, it has a constituent phase mainly composed of Zn ₂ SnO ₄ phase, InGaZnO ₄ phase, InGaZn ₂ O ₅ phase, In ₂ O ₃ phase, and SnO ₂ phase. Furthermore, impurities such as oxides that are inevitably mixed or generated in production may be included.

The relative density of the oxide sintered body is preferably 95% or more. Thereby, the strength of the oxide sintered body can be increased, and the cracking of the oxide sintered body during welding to the base plate can be effectively suppressed. The relative density is more preferably 97% or more, and further preferably 99% or more.

The relative density in this specification can be obtained as follows.

The oxide sintered body prepared as a sample for measurement is cut in an arbitrary position in the thickness direction, and any position of the cut surface is mirror-polished. Next, a scanning electron microscope (Scanning Electron Microscope, SEM) was used to take a photograph at a suitable magnification (for example, a magnification of 1000 times), and the area ratio (%) of the pores in the area of 100 μm square was measured as “porosity (%) ". In the same sample, the same porosity measurement was performed on the cut surfaces of 20 locations, and the average value of the porosity obtained by 20 measurements was taken as the average porosity (%) of the sample. The value obtained by [100-average porosity] is taken as the "relative density" in this specification (%) ".

FIG. 2 shows an example of the secondary electron image (magnification: 1000 times) of the oxide sintered body. In Fig. 2, the black dotted portions are pores. The pores can be easily identified with other metal structures in any of SEM photos and secondary electron images.

Regarding the pores in the oxide sintered body, it is preferable that not only the porosity is low, but also the pore size is small.

When the molded body including pores is sintered, small pores disappear due to sintering, but large pores do not disappear and remain inside the oxide sintered body. The pores in the oxide sintered body exist in a compressed state. Moreover, there is a phenomenon that Sn, Ga, etc. in the molded body are decomposed during sintering, and pores are generated inside the oxide sintered body. The compressed gas may also be present inside the pores generated as described above. In the oxide sintered body, if there are pores containing compressed gas, internal stress becomes high, and the mechanical strength and thermal shock resistance of the oxide sintered body decrease.

The larger the pores, the higher the cracking of the oxide sintered body due to the pores. Therefore, by suppressing the size of pores in the oxide sintered body to be small, the mechanical strength of the oxide sintered body can be improved, thereby suppressing cracking of the oxide sintered body. By setting the maximum circle equivalent diameter D _{max of the} pores to 3 μm or less, the internal stress can be sufficiently reduced. The maximum circle-equivalent diameter of the porosity is more preferably 2 μm or less.

Furthermore, the relative circle equivalent diameter D _ave (μm) of the pores in the oxide sintered body is preferably 0.3 or more and 1.0 or less relative to the maximum circle equivalent diameter D _max (μm) (that is, 0.3 ≦ D _ave / D _max ≦ 1.0). When the relative ratio is 1.0, it becomes a circle, and as the relative ratio becomes smaller, it becomes a flat ellipse.

If the shape of the pores is elliptical, the oxide sintered body with reduced mechanical strength becomes more likely to crack than in the case of a circle. In particular, the flatter ellipse becomes, the more prominent this tendency becomes. Therefore, by making the relative ratio 0.3 or more, the strength of the oxide sintered body can be improved. The relative ratio is more preferably 0.5 or more.

The maximum circle equivalent diameter and average circle equivalent diameter of pores in this specification can be obtained as follows.

The oxide sintered body prepared as a sample for measurement is cut in an arbitrary position in the thickness direction, and any position of the cut surface is mirror-polished. Next, a scanning electron microscope (SEM) is used to take a photograph at a suitable magnification (for example, a magnification of 1000 times), and the circle-equivalent diameter of all pores existing in the area of 100 μm square is obtained. In the same sample, the circle-equivalent diameters of all the pores were similarly determined on the cut surfaces at 20 locations. The largest circle equivalent diameter among all circle equivalent diameters obtained in 20 measurements is taken as the "maximum circle equivalent diameter of pores" of the oxide sintered body, and the average value of all circle equivalent diameters is taken as the oxide sintered body "Average circle equivalent diameter of stomata".

If the crystal grains of the oxide sintered body are made fine, the effect of suppressing cracking of the oxide sintered body when welding to the base plate can be improved. The average crystal grain size of the crystal grains is preferably 20 μm or less, whereby the effect of suppressing cracking of the oxide sintered body can be further improved. The average crystal grain size is more preferably 17 μm or less, and still more preferably 15 μm or less.

On the other hand, the lower limit of the average grain size is not particularly limited, but since the average Considering the balance between the miniaturization of the grain size and the manufacturing cost, the preferred lower limit of the average grain size is about 0.05 μm.

The average grain size of the crystal grains can be measured as described below.

The oxide sintered body prepared as a sample for measurement is cut in an arbitrary position in the thickness direction, and any position of the cut surface is mirror-polished. Next, a scanning electron microscope (SEM) is used to take a picture of the tissue of the cut surface at a suitable magnification (for example, a magnification of 400 times). On a photograph taken, a straight line corresponding to a length of 100 μm in actual measurement (that is, “equivalent to 100 μm in actual measurement”) is drawn in any direction, and the number of crystal grains (N) existing on the straight line is obtained. The value calculated by [100 / N] (μm) is regarded as the "grain size on a straight line". Furthermore, 20 straight lines corresponding to the actual measured length of 100 μm were made on the photo, and the grain size on each straight line was calculated. In addition, the value calculated by [(total grain size on each straight line) / 20] is taken as the “average grain size of oxide sintered body” in this specification.

Furthermore, it is preferable to control the particle size distribution appropriately in addition to controlling the average grain size of the crystal grains of the oxide sintered body. In particular, coarse crystal grains having a grain size exceeding 30 μm cause cracks in the oxide sintered body during welding, and therefore can be as small as possible. The coarse grains with a grain size exceeding 30 μm are preferably 10% or less, more preferably 8% or less, further preferably 6% or less, further preferably 4% or less, and most preferably 0% in terms of area ratio. .

The area ratio of crystal grains with a crystal grain size exceeding 30 μm can be measured as follows.

In the measurement of the "average grain size of crystal grains", when a line corresponding to a length of 100 μm is drawn, the length of the crystal cut from the line becomes 30 μm or more As "coarse grains". On a straight line with a length of 100 μm, the length occupied by the coarse grains (that is, the length of the portion transverse to the coarse grains in the straight line) is taken as L (μm). The value of L (μm) divided by 100 (μm) was taken as the ratio R (%) of coarse particles on the straight line.

R (%) = (L (μm) / 100 (μm)) × 100 (%)

In addition, when there are a plurality of coarse grains on a straight line with a length of 100 μm, the total length of the portion transverse to each coarse grain is taken as L (μm), and the ratio R (%) of the coarse grains is obtained.

In each of the 20 straight lines drawn in the measurement of the average grain size of the crystal grains, the ratio R (%) of coarse grains was obtained, and the average value thereof was taken as the ratio of coarse grains of the sintered body.

The specific resistance of the oxide sintered body is preferably ¹ Ω‧cm or less, more preferably 10 ^-1 Ω‧cm or less, and further preferably 10 ^-2 Ω‧cm or less. As described later, the oxide sintered body is fixed to the bottom plate to form a sputtering target. When the sputtering target is used, the specific resistance of the oxide sintered body is suppressed to be low, thereby suppressing abnormal discharge during sputtering, and further suppressing cracking of the oxide sintered body due to abnormal discharge. This can suppress the film formation cost of the oxide semiconductor thin film using the sputtering target. Furthermore, it is possible to suppress film formation defects caused by abnormal discharge during sputtering, and thereby it is possible to manufacture an oxide semiconductor thin film having uniform and good characteristics.

For example, in a production line for manufacturing a display device, by using a sputtering target to manufacture an oxide semiconductor thin film of a TFT, the manufacturing cost of the TFT can be suppressed, and further the manufacturing cost of the display device can be suppressed. Furthermore, an oxide semiconductor thin film exhibiting good TFT characteristics can be formed, so that a high-performance display device can be manufactured.

The specific resistance of the oxide sintered body can be measured by the four-probe method. Specifically, the specific resistance of the oxide sintered body can be measured using a known specific resistance measuring device (for example, Loresta GP manufactured by Mitsubishi Chemical Analytech). In addition, the specific resistance in this specification is obtained by measuring the distance between each terminal to 1.5 mm. The specific resistance was measured multiple times (for example, 4 times) at different positions, and the average value was used as the specific resistance of the oxide sintered body.

<Sputtering target>

Next, a sputtering target using an oxide sintered body will be described.

FIG. 1 is a schematic cross-sectional view of a sputtering target 1. The sputtering target 1 includes a base plate 20 and an oxide sintered body 10 fixed to the base plate 20 by a welding material 30.

The oxide sintered body of the embodiment of the present invention is used for the oxide sintered body 10. Therefore, when welding to the base plate 20 by the welding material 30, the oxide sintered body is hard to crack, and the sputtering target 1 can be manufactured with good yield.

<Manufacturing method>

Next, the method for manufacturing the oxide sintered body and the sputtering target according to the embodiment of the present invention will be described.

The oxide sintered body according to the embodiment of the present invention can be obtained by sintering a mixed powder containing zinc oxide, indium oxide, gallium oxide, tin oxide, and zirconium oxide. The sputtering target according to the embodiment of the present invention can be obtained by fixing the obtained oxide sintered body on the bottom plate.

In more detail, the oxide sintered body can pass the following steps (a) to (e) And manufacture. The sputtering target can be manufactured by the following steps (f) and (g).

Step (a): Mix and crush the oxide powder

Step (b): drying and granulating the obtained mixed powder

Step (c): Preforming the granulated mixed powder

Step (d): Degrease the preformed body

Step (e): sinter the degreased shaped body to obtain an oxide sintered body

Step (f): processing the obtained oxide sintered body

Step (g): Weld the processed oxide sintered body to the bottom plate to obtain a sputtering target

In the embodiment of the present invention, in step (a), control is performed so that the mixed powder contains an appropriate amount of zirconia. In step (e), the sintering conditions are controlled so that the oxide sintered body has a density higher than a predetermined density. In addition, in the step (e), it is preferable to control the sintering conditions in such a manner that the grain size enters a preferable range. Steps (b) to (d), (f) and (g) are not particularly limited if they can produce oxide sintered bodies and sputtering targets, and can be suitably applied to oxide sintered bodies and sputtering targets Steps commonly used in the manufacture of wood. Hereinafter, each step will be described in detail, but the embodiments of the present invention are not limited to these steps.

(Step (a): Mix and crush oxide powder)

Zinc oxide, indium oxide powder, gallium oxide powder, and tin oxide powder are mixed in a predetermined ratio, mixed, and pulverized. The purity of each raw material powder used is preferably about 99.99% or more. The reason is that if there are traces of impurity elements, then There is a possibility of impairing the semiconductor characteristics of the oxide semiconductor thin film.

The "prescribed ratio" of each raw material powder refers to the content of zinc, indium, gallium, and tin contained in the oxide sintered body obtained after sintering, relative to all metal elements (zinc, indium, gallium, and The ratio of tin) is within the range of the following formula (1) to formula (3).

35 atomic% ≦ [Zn] ≦ 55 atomic% ‧‧‧‧ (1)

20 atom% ≦ ([In] + [Ga]) ≦ 55 atom% ‧‧‧‧ (2)

5 atomic% ≦ [Sn] ≦ 25 atomic% ‧‧‧‧ (3)

Normally, the content of zinc, indium, gallium, and tin contained in the mixed powder after mixing each raw material powder (zinc oxide, indium oxide powder, gallium oxide powder, and tin oxide powder) relative to oxygen The ratio of all the metal elements in the above-mentioned formulas (1) to (3) may be used to mix the raw material powders.

In mixing and pulverizing, it is preferable to use a ball mill or a bead mill. The raw material powder and water are put into a grinding device, and the raw material powder is pulverized and mixed to obtain a mixed powder. At this time, the raw material powder may be uniformly mixed, and a dispersion material may be added and mixed, or a binder may be further added and mixed to make it easier to form a molded body afterwards.

As the balls or particles used in the ball mill and bead mill (these are referred to as "mediums"), those containing zirconia can be used. When mixing and pulverizing, a small amount of zirconia is added to the mixed powder due to media surface wear. In this method, if the mixing time is long, the amount of wear of the medium (that is, the amount of zirconia added) increases. Therefore, by adjusting the mixing time, it can be adjusted in the mixed powder with good accuracy The amount of zirconia added.

As the medium used in the ball mill and the bead mill, nylon or alumina can also be used. In this case, zirconia powder is added as a raw material powder so that a predetermined amount of zirconia is contained in the mixed powder. In this case, since the mixed powder containing the predetermined zirconia can be obtained regardless of the mixing time, the mixing time can be arbitrarily set.

For the container used in the ball mill and the bead mill, a nylon container, an alumina container, and a zircon container can be used.

A zirconia powder may be further added as a raw material powder, or a zirconia medium may be further used as a medium. In this case, part of the desired amount of zirconia is added as the raw material powder, and the remaining part is added due to media wear.

The mixing time of the ball mill or bead mill is preferably 3 hours or more, more preferably 10 hours or more, and still more preferably 20 hours or more.

(Step (b): drying and granulating the mixed powder)

The mixed powder obtained in step (a) is preferably dried and granulated by, for example, a spray dryer.

(Step (c): Preforming the granulated mixed powder)

Preferably, the mixed powder after granulation is filled in a metal mold of a predetermined size, and a predetermined pressure (for example, about 49 MPa to about 98 MPa) is applied to a predetermined shape by pressing with a metal mold.

In the case of performing sintering in step (e) by hot pressing, step (c) may be omitted, or the mixed powder may be filled in a metal mold for sintering to perform pressure firing As a result, a dense oxide sintered body is produced. In addition, in order to facilitate the operation, after preforming in step (c), the molded body may be placed in a molding die for sintering and hot-pressed.

On the other hand, in the case where the sintering in step (e) is performed by normal pressure sintering, a dense oxide sintered body can be manufactured by performing preforming in step (c).

(Step (d): Degrease the preformed body)

In the step (a), when the dispersion material and / or the binder is added to the mixed powder, it is preferable to heat the molded body to remove the dispersion material and the binder in the molded body (that is, to degrease). The heating conditions (heating temperature and holding time) are not particularly limited as long as the temperature and time at which the dispersion material and the binder can be removed. For example, the molded body can be maintained in the atmosphere at a heating temperature of about 500 ° C. for about 5 hours.

In the step (a), when the dispersing material and the binder are not used, the step (d) may be omitted.

When step (c) is omitted, that is, when sintering is performed by hot pressing in step (e) and the molded body is not formed, the mixed powder may also be heated to disperse the mixed material And adhesive removal (degreasing).

(Step (e): sintering the shaped body to obtain an oxide sintered body)

The degreased shaped body is sintered under predetermined sintering conditions to obtain an oxide sintered body. As the sintering method, any one of hot pressing and normal pressure sintering can be used. Hereinafter, the sintering conditions and the like will be described for each of hot pressing and normal pressure sintering.

(i) Hot pressing

During hot pressing, the molded body is placed in a state where the molded body is placed in the molding die for sintering In the sintering furnace, sintering is carried out under pressure. Sintering the molded body while applying pressure to the molded body can suppress the sintering temperature to be relatively low to obtain a dense oxide sintered body.

In the hot press, a forming mold for sintering to press the formed body is used. As the forming mold for sintering, any one of a metal mold (metal mold) and a graphite mold (graphite mold) may be used according to the sintering temperature. Particularly preferred is a graphite mold with excellent heat resistance, and can also withstand high temperatures above 900 ° C.

The pressure applied to the forming die is not particularly limited, but the surface pressure (pressurizing pressure) is preferably 10 MPa to 39 MPa. If the pressure is too high, there is a possibility that the graphite mold for sintering may be damaged, and large-scale pressing equipment becomes necessary. Furthermore, if it exceeds 39 MPa, the effect of promoting the densification of the sintered body is saturated, and therefore there is little benefit in pressurizing at a pressure higher than that. On the other hand, if the pressure is less than 10 MPa, it is difficult to sufficiently densify the sintered body. The better pressure condition is 10MPa ~ 30MPa.

The sintering temperature may be equal to or higher than the temperature at which the mixed powder in the molded body is sintered. For example, if the sintering is performed under a surface pressure of 10 MPa to 39 MPa, the sintering temperature is preferably 900 ° C to 1200 ° C.

If the sintering temperature is 900 ° C. or higher, sintering is sufficiently performed, and the density of the obtained oxide sintered body can be increased. The sintering temperature is more preferably 920 ° C or higher, and further preferably 940 ° C or higher. Furthermore, if the sintering temperature is 1200 ° C. or lower, the growth of crystal grains during sintering is suppressed, and the crystal grain size in the oxide sintered body can be reduced. The sintering temperature is more preferably 1100 ° C or lower, and further preferably 1000 ° C or lower.

The holding time (holding time) at the specified sintering temperature is sufficient The mixed powder is sintered, and the density of the obtained oxide sintered body becomes a predetermined density or more for a period of time. For example, if the sintering temperature is 900 ° C to 1200 ° C, the holding time is preferably 1 hour to 12 hours.

If the holding time is 1 hour or more, the structure in the obtained oxide sintered body can be made uniform. The holding time is more preferably 2 hours or more, and further preferably 3 hours or more. Moreover, if the holding time is 12 hours or less, the growth of crystal grains during sintering can be suppressed, and the crystal grain size in the oxide sintered body can be reduced. The holding time is more preferably 10 hours or less, and further preferably 8 hours or less.

The average heating rate up to the sintering temperature can affect the size of the crystal grains in the oxide sintered body and the relative density of the oxide sintered body. The average temperature increase rate is preferably 600 ° C./hr or less. Since it is difficult to cause abnormal growth of crystal grains, the ratio of coarse crystal grains can be suppressed. Furthermore, if it is 600 ° C./hr or less, the relative density of the sintered oxide sintered body can be increased. The average temperature increase rate is more preferably 400 ° C / hr or less, and further preferably 300 ° C / hr or less.

The lower limit of the average temperature increase rate is not particularly limited, and from the viewpoint of productivity, it is preferably 50 ° C / hr or more, and more preferably 100 ° C / hr or more.

In the sintering step, in order to suppress the oxidation and disappearance of the graphite mold for sintering, it is preferable to set the sintering environment to an inert gas environment. For a suitable inert environment, for example, an environment of inert gas such as Ar gas and N ₂ gas can be used. For example, by introducing an inert gas into the sintering furnace, the sintering environment can be adjusted. Furthermore, from the viewpoint of suppressing the evaporation of a metal having a high vapor pressure, it is desirable to set the pressure of the ambient gas to atmospheric pressure or vacuum (that is, a pressure lower than atmospheric pressure).

(ii) Atmospheric pressure sintering

In normal pressure sintering, the formed body is placed in a sintering furnace, and sintering is performed under normal pressure. In addition, in normal pressure sintering, since no pressure is applied during sintering, it is difficult to perform sintering. Therefore, sintering is generally performed at a sintering temperature higher than hot pressing.

The sintering temperature is not particularly limited if it is equal to or higher than the temperature at which the mixed powder in the molded body is sintered. For example, the sintering temperature may be 1450 ° C to 1600 ° C.

If the sintering temperature is 1450 ° C. or higher, sintering is sufficiently performed, and the density of the obtained oxide sintered body can be increased. The sintering temperature is more preferably 1500 ° C or higher, and further preferably 1550 ° C or higher. Moreover, if the sintering temperature is 1600 ° C. or lower, the growth of crystal grains during sintering can be suppressed, and the crystal grain size in the oxide sintered body can be reduced. The sintering temperature is more preferably 1580 ° C or lower, and further preferably 1550 ° C or lower.

The holding time is not particularly limited as long as the mixed powder is sufficiently sintered and the density of the obtained oxide sintered body is equal to or higher than a predetermined density. For example, it can be set to 1 hour to 5 hours.

If the holding time is 1 hour or more, the structure in the obtained oxide sintered body can be made uniform. The holding time is more preferably 2 hours or more, and further preferably 3 hours or more. Moreover, if the holding time is 5 hours or less, the growth of crystal grains during sintering can be suppressed, and the crystal grain size in the oxide sintered body can be reduced. The holding time is more preferably 4 hours or less, and further preferably 3 hours or less.

The average temperature increase rate is preferably 100 ° C./hr or less. Since it is difficult to cause abnormal growth of crystal grains, the proportion of coarse crystal grains can be suppressed. Furthermore, if it is 100 ° C./hr or less, the relative density of the sintered oxide sintered body can be increased. Average heating rate The degree is more preferably 90 ° C / hr or less, and further preferably 80 ° C / hr or less.

The lower limit of the average temperature increase rate is not particularly limited, and from the viewpoint of productivity, it is preferably 50 ° C / hr or more, and more preferably 60 ° C / hr or more.

The sintering environment is preferably atmospheric or oxygen-enriched environment. It is particularly desirable that the oxygen concentration in the environment is 50% by volume to 100% by volume.

As described above, the oxide sintered body can be manufactured through the steps (a) to (e).

(Step (f): processing the oxide sintered body)

The obtained oxide sintered body may also be processed into a shape suitable for sputtering targets. The processing method of the oxide sintered body is not particularly limited, and it can be processed into a shape corresponding to various uses by a known method.

(Step (g): Weld the oxide sintered body to the bottom plate)

As shown in FIG. 1, the processed oxide sintered body 10 is joined to the base plate 20 by the welding material 30. Thereby, the sputtering target 1 is obtained. The material of the bottom plate 20 is not particularly limited, but it is preferably pure copper or a copper alloy excellent in thermal conductivity. Various well-known solder materials having electrical conductivity can be used for the solder material 30, and for example, In-type solder materials and Sn-type solder materials are suitable. The joining method is not particularly limited as long as the welding material 30 is used to join the base plate 20 and the oxide sintered body 10. As an example, the oxide sintered body 10 and the base plate 20 are heated to a temperature at which the welding material 30 dissolves (for example, about 140 ° C to about 220 ° C). After the molten welding material 30 is applied to the welding surface 23 of the bottom plate 20 (the surface to which the oxide sintered body 10 is fixed, that is, the upper surface of the bottom plate 20), the oxide sintered body 10 is placed on the welding surface 23. By combining the bottom plate 20 with oxide The sintered body 10 is cooled while being pressed, and the welding material 30 can be solidified, thereby fixing the oxide sintered body 10 to the welding surface 23.

[Example]

Hereinafter, the embodiments of the present invention will be described more specifically by exemplifying examples. However, the present invention is not limited to the following examples, and can be implemented with appropriate changes within the scope suitable for the gist of the present invention. It is included in the technical scope of the present invention.

<Example 1>

(Production of sputtering target)

Zinc oxide powder (ZnO) with a purity of 99.99%, indium oxide powder (In ₂ O ₃ ) with a purity of 99.99%, and gallium oxide powder (Ga with a purity of 99.99%) were prepared at the atomic ratio (atomic%) shown in Table 1. ₂ O ₃ ), tin oxide powder (SnO ₂ ) with a purity of 99.99% as a raw material powder. Water and dispersant (ammonium polycarboxylate) were added and mixed and pulverized by a ball mill for 20 hours. In this example, a ball mill was used, which used a nylon container and zirconia balls as a medium. Next, the mixed powder obtained in the above step is dried and granulated.

Pressing with a metal mold and pressing at a pressure of 1.0 ton / cm ² , the obtained mixed powder was formed into a disc-shaped molded body having a diameter of 110 mm × thickness of 13 mm. The molded body was heated to 500 ° C. under normal pressure and atmospheric environment, and kept at this temperature for 5 hours to perform degreasing. The degreased molded body was placed in a graphite mold, and hot-pressed under the following conditions. At this time, N ₂ gas was introduced into the hot-press furnace, and sintering was performed in an N ₂ environment.

Maintain temperature: 920 ℃

Hold time: 3 hours

Average heating rate up to sintering temperature: 200 ℃ / hr

Surface pressure: 30MPa

The obtained oxide sintered body was mechanically processed and finished to a diameter of 100 mm × thickness of 5 mm to obtain an oxide sintered body for measurement. After the oxide sintered body for measurement and the Cu base plate were heated to 180 ° C. for 10 minutes, the lower surface of the oxide sintered body was welded to the upper surface of the base plate using a welding material (indium) to prepare a sputtering target.

<Comparative Example 1>

Except having changed the mixing time to 1 hour, it carried out similarly to Example 1, and produced the sputtering target of Comparative Example 1. FIG.

(Zirconium content)

Regarding each example and comparative example, the zirconium content of the oxide sintered body was measured as follows. First, the entire upper surface of the oxide sintered body fixed to the bottom plate is polished by 0.5 mm or more to remove black skin on the surface. Next, about 5g of oxide sintered body was cut from the upper surface of the oxide sintered body by ICP analysis Quantitative analysis of zirconium content. The same measurement was performed three times. Table 2 shows the average value of the three measured values of the amount of zirconium.

(Measurement of relative density)

The relative density of the oxide sintered body of each example and comparative example can be obtained using the porosity measured as follows.

The oxide sintered body is cut at any position in the thickness direction, and the cut surface is mirror-polished at any position. Next, a scanning electron microscope (SEM) was used to take a photograph at a magnification of 1,000 times, and the area ratio (%) of the pores in the area of 100 μm square was measured as “porosity (%)”. In the same sample, the same porosity measurement was performed on the cut surfaces of 20 locations, and the average value of the porosity obtained by 20 measurements was taken as the average porosity (%) of the sample. The value obtained by [100-average porosity] is referred to as "relative density (%)" in this specification. Table 2 shows the measurement results of the relative density.

(Average grain size)

The “average grain size (μm)” of the oxide sintered bodies of each example and comparative example was measured as follows. First, the oxide sintered body is cut at any position in the thickness direction, and the cut surface is mirror-polished at any position. Secondly, a scanning electron microscope (SEM) was used to take a photograph of the cut tissue at a magnification of 400 times. On the photograph taken, a straight line with a length of 100 μm is drawn in any direction, and the number of crystal grains (N) existing on the straight line is obtained. The value calculated by [100 / N] (μm) is regarded as the "grain size on a straight line". Furthermore, 20 straight lines corresponding to a length of 100 μm were made on the photo, and the grain size on each straight line was calculated. In addition, in When multiple straight lines are drawn, in order to avoid counting the same crystal grains multiple times, the straight lines are drawn so that the distance between adjacent straight lines becomes at least 20 μm (corresponding to the particle size of coarse grains).

In addition, the value calculated by [(total grain size on each straight line) / 20] was taken as "average grain size of oxide sintered body". Table 2 shows the measurement results of the average grain size.

(Cracked during welding)

Regarding the oxide sintered body of each example and comparative example, it was investigated whether cracking occurred when the welding material was welded to the base plate.

After the mechanically processed oxide sintered body was welded to the base plate under the above conditions, it was visually confirmed whether or not cracks occurred on the surface of the oxide sintered body. When cracks exceeding 1 mm in length were confirmed on the surface of the oxide sintered body, it was determined that “cracking occurred”, and when cracks exceeding 1 mm in length were not confirmed, it was determined that “cracking did not occur”.

For each of the examples and comparative examples, 10 pieces of machined oxide sintered bodies were prepared, and the operation of welding to the base plate 10 times was performed. When even one of the oxide sintered bodies cracks, it is described as “cracking” in Table 2. When all 10 pieces did not break, it was described as "none" in Table 2.

(Abnormal discharge)

The oxide sintered body of each example and comparative example was processed into a shape having a diameter of 100 mm and a thickness of 5 mm, and was welded to a bottom plate to obtain a sputtering target. The sputtering target material obtained as described above was mounted on a sputtering device, and direct-current (DC) magnetron sputtering was performed. The sputtering conditions were DC sputtering power of 200 W, Ar-O ₂ environment (Ar / O ₂ = 10% by volume in terms of volume ratio), and a pressure of 1 mTorr. At this time, the number of times of arc generation per 100 min. Was counted, and the case of less than 3 times was regarded as a pass, and it was described as "OK" in Table 2.

In addition, in Comparative Example 1, the oxide sintered body cracked when being welded to the base plate, so the sputtering target could not be manufactured. Therefore, in Comparative Example 1, no experiment on abnormal discharge was conducted.

In Examples 1 to 6 having a composition within the range specified in the embodiments of the present invention and the amount of zircon, no cracks were generated when the oxide sintered body was welded to the bottom plate. In addition, the sputtering targets of Examples 1 to 6 were used for sputtering. As a result, no abnormal discharge was generated during sputtering, and no cracks were generated in the oxide sintered body during sputtering.

On the other hand, in Comparative Example 1 in which the amount of zircon is smaller than the lower limit of the range defined in the embodiment of the present invention, when the oxide sintered body was welded to the bottom plate, all 10 pieces were cracked.

The disclosed invention includes the following embodiments.

Embodiment 1:

An oxide sintered body containing 50 ppm to 500 ppm of zirconium, and the ratio (atomic%) of the contents of zinc, indium, gallium, and tin to all metal elements except oxygen is set to [Zn], [In] , [Ga] and [Sn], the following formula (1) to formula (3) are satisfied: 35 atomic% ≦ [Zn] ≦ 55 atomic% ‧‧‧‧ (1)

20 atom% ≦ ([In] + [Ga]) ≦ 55 atom% ‧‧‧‧ (2)

5 atomic% ≦ [Sn] ≦ 25 atomic% ‧‧‧‧ (3)

Embodiment 2:

The oxide sintered body according to Embodiment 1, wherein the relative density is 95% or more.

Embodiment 3:

The oxide sintered body according to Embodiment 1 or 2, wherein the pores in the oxide sintered body have a maximum circle-equivalent diameter of 3 μm or less.

Embodiment 4:

The oxide sintered body according to any one of Embodiment 1 to Embodiment 3, wherein the average circular equivalent diameter (μm) of the pores in the oxide sintered body relative to the maximum circular equivalent diameter (μm) The ratio is 0.3 or more and 1.0 or less.

Embodiment 5:

The oxide sintered body according to any one of Embodiment 1 to Embodiment 4, wherein the average crystal grain size is 20 μm or less.

Embodiment 6:

The oxide sintered body according to any one of Embodiment 1 to Embodiment 5, wherein the area ratio of crystal grains having a crystal grain size exceeding 30 μm is 10% or less.

Embodiment 7:

The oxide sintered body according to any one of Embodiment 1 to Embodiment 6, wherein the specific resistance is 1 Ω · cm or less.

Embodiment 8:

A sputtering target material obtained by fixing an oxide sintered body according to any one of Embodiment 1 to Embodiment 7 on a bottom plate with a welding material.

Embodiment 9:

A method for manufacturing an oxide sintered body, which is a method for manufacturing an oxide sintered body according to any one of Embodiment 1 to Embodiment 7, which includes the following steps: preparing to contain zinc oxide, indium oxide in a predetermined ratio The step of mixing powder of gallium oxide, tin oxide, and zirconium oxide is a step of sintering the mixed powder into a predetermined shape.

Embodiment 10:

The manufacturing method according to Embodiment 9, wherein the step of preparing the mixed powder includes using a ball mill or a bead mill containing a medium containing zirconia, and containing the zinc oxide, indium oxide, gallium oxide, and tin oxide. The step of mixing raw material powder.

Embodiment 11:

The manufacturing method according to Embodiment 9, wherein the step of preparing the mixed powder includes using a ball mill or bead mill to contain zinc oxide, indium oxide, gallium oxide, The step of mixing raw material powders of tin oxide and zirconium oxide.

Embodiment 12:

The manufacturing method according to any one of Embodiment 9 to Embodiment 11, wherein the sintering step includes a state where a surface pressure of 10 MPa to 39 MPa is applied to the mixed powder by a forming die, The step of holding for 1 hour to 12 hours at a sintering temperature of 900 ° C to 1200 ° C.

Embodiment 13:

The manufacturing method according to Embodiment 12, wherein in the sintering step, the average temperature increase rate up to the sintering temperature is 600 ° C./hr or less.

Embodiment 14:

The manufacturing method according to any one of Embodiment 9 to Embodiment 11, which further includes a step of preforming the mixed powder after the step of preparing the mixed powder and before the step of sintering. The sintering step includes the step of holding the preformed molded body at normal pressure at a sintering temperature of 1450 ° C to 1600 ° C for 1 hour to 5 hours.

Embodiment 15:

The manufacturing method according to Embodiment 14, wherein in the sintering step, the average temperature increase rate up to the sintering temperature is 100 ° C./hr or less.

Embodiment 16:

A method for manufacturing a sputtering target material, which comprises welding an oxide sintered body as described in any one of Embodiments 1 to 7 or any one of Embodiments 9 to 15 by welding materials Sintered oxide manufactured by the manufacturing method The step of body bonding to the bottom plate.

This application claims the Japanese patent application with the application date of April 13, 2016, Japanese Patent Application No. 2016-80333 and the Japanese patent application with the application date of January 19, 2017, Japanese Patent Application No. 2017-7848 No. is the priority of the basic application. Japanese Patent Application No. 2016-80333 and Japanese Patent Application No. 2017-7848 are incorporated into this specification by reference.

Claims (16)

An oxide sintered body, which contains 50 ppm to 500 ppm of zirconium, a mixed powder containing zinc oxide, indium oxide, gallium oxide, tin oxide, and zirconium oxide in a prescribed ratio at a sintering temperature of 1000 ° C or less and 3 An oxide sintered body obtained by sintering by hot pressing for a holding time of more than hours, and containing 50 ppm to 500 ppm of zirconium, a relative density of 95% or more, and the content of zinc, indium, gallium and tin relative to oxygen except When the ratio (atomic%) of all metal elements is set to [Zn], [In], [Ga], and [Sn], the following formula (1) to formula (3) are satisfied: 35 atomic% ≦ [Zn] ≦ 55 atom% ‧‧‧‧ (1) 20 atom% ≦ ([In] + [Ga]) ≦ 55 atom% ‧‧‧‧ (2) 5 atom% ≦ [Sn] ≦ 25 atom% ‧‧‧‧ (3) . An oxide sintered body, which contains 50 ppm to 500 ppm of zirconium, a mixed powder containing zinc oxide, indium oxide, gallium oxide, tin oxide, and zirconium oxide in a prescribed ratio at a sintering temperature of 1550 ° C or less and 3 An oxide sintered body obtained by sintering at atmospheric pressure for a holding time of more than hours, and containing 50 ppm to 500 ppm of zirconium, a relative density of 95% or more, and the content of zinc, indium, gallium and tin relative to all except oxygen When the ratio (atomic%) of metal elements is set to [Zn], [In], [Ga], and [Sn], respectively, the following formula (1) to formula (3) are satisfied: 35 atomic% ≦ [Zn] ≦ 55 Atomic% ‧‧‧‧ (1) 20 atomic% ≦ ([In] + [Ga]) ≦ 55 atomic% ‧‧‧‧ (2) 5 atomic% ≦ [Sn] ≦ 25 atomic% ‧‧‧‧ (3) The oxide sintered body according to item 1 or 2 of the scope of the patent application, wherein the maximum circular equivalent diameter of the pores in the oxide sintered body is 3 μm or less. The oxide sintered body as described in item 1 or 2 of the patent application range, wherein the relative ratio of the average circle equivalent diameter (μm) of the pores in the oxide sintered body to the maximum circle equivalent diameter (μm) It is 0.3 or more and 1.0 or less. The oxide sintered body as described in item 1 or 2 of the patent application, wherein the average grain size is 20 μm or less. The oxide sintered body according to item 1 or 2 of the patent application, wherein the area ratio of crystal grains having a grain size exceeding 30 μm is 10% or less. The oxide sintered body as described in item 1 or item 2 of the scope of patent application, wherein the specific resistance is 1Ω‧cm or less. A sputtering target material obtained by fixing an oxide sintered body as described in item 1 or item 2 of a patent application to a base plate by a welding material. A method for manufacturing an oxide sintered body, which is a method for manufacturing an oxide sintered body as described in item 1 or 2 of the patent application, which includes the following steps: in a manner containing 50 ppm to 500 ppm of zirconium, preparing to The step of containing a mixed powder of zinc oxide, indium oxide, gallium oxide, tin oxide, and zirconium oxide at a predetermined ratio, and the step of sintering the mixed powder into a predetermined shape. The method for manufacturing an oxide sintered body as described in item 9 of the patent application range, wherein the step of preparing the mixed powder includes using a ball mill or a bead mill containing a medium containing zirconium oxide to The step of mixing raw material powders of indium, gallium oxide, and tin oxide. The method for manufacturing an oxide sintered body as described in item 9 of the patent application range, wherein the step of preparing the mixed powder includes using a ball mill or a bead mill to convert zinc oxide, indium oxide, gallium oxide, tin oxide and The step of mixing the raw material powder of zirconia. The method for manufacturing an oxide sintered body according to item 9 of the patent application range, wherein the sintering step includes a state where a surface pressure of 10 MPa to 39 MPa is applied to the mixed powder by a forming die, The step of maintaining at a sintering temperature of 900 ° C to 1000 ° C for 3 hours to 12 hours. The method for manufacturing an oxide sintered body according to item 12 of the patent application range, wherein in the sintering step, the average temperature increase rate up to the sintering temperature is 600 ° C./hr or less. The method for manufacturing an oxide sintered body as described in item 9 of the scope of the patent application further includes the step of preforming the mixed powder after the step of preparing the mixed powder and before the step of sintering. The sintering step includes the step of holding the preformed molded body at normal pressure at a sintering temperature of 1450 ° C to 1550 ° C for 3 hours to 5 hours. The method for manufacturing an oxide sintered body according to item 14 of the patent application range, wherein in the sintering step, the average temperature increase rate up to the sintering temperature is 100 ° C./hr or less. A method for manufacturing a sputtering target material, which comprises welding an oxide sintered body as described in item 1 or 2 of the patent application or by an oxide as described in item 9 of the patent application The step of bonding the oxide sintered body produced by the sintered body manufacturing method to the base plate.