CN107779821B

CN107779821B - Sintered body, sputtering target, and method for producing same

Info

Publication number: CN107779821B
Application number: CN201710734442.2A
Authority: CN
Inventors: 挂野崇; 梶山纯
Original assignee: JX Nippon Mining and Metals Corp
Current assignee: JX Nippon Mining and Metals Corp
Priority date: 2016-08-29
Filing date: 2017-08-24
Publication date: 2020-12-18
Anticipated expiration: 2037-08-24
Also published as: TW201806909A; TWI649293B; KR20180025225A; CN107779821A; KR101921827B1; JP2018035013A; JP6267297B1

Abstract

The invention provides a sintered body, a sputtering target and a manufacturing method thereof, wherein the sintered body can effectively inhibit the volume resistivity deviation of the surface and the inside of the sintered body in an IZO target. The sintered body of the present invention is the sintered body containing an oxide of In, Zn, O, and a ratio of a difference between a volume resistivity Rs at a depth position of 1mm In a thickness direction from a surface of the sintered body and a volume resistivity Rd at a depth position of 4mm In a thickness direction from the surface of the sintered body divided by the volume resistivity Rd at the depth position of 4mm, that is, an absolute value of (Rs-Rd)/Rd is 20% or less In percentage.

Description

Sintered body, sputtering target, and method for producing same

Technical Field

The present invention relates to a sintered body containing In, Zn, and O, a sputtering target called an IZO target containing the sintered body for forming a transparent conductive film or the like, and a method for manufacturing the sputtering target, and particularly proposes a technique capable of contributing to forming a stable IZO film during sputtering.

Background

For example, in the production of electrodes for Liquid Crystal Displays (LCDs), Electroluminescence (ELs), and other various display devices mounted on personal computers, word processors, and the like, electrodes for touch panels, films for electronic paper, and the like, a transparent conductive film containing a metal complex oxide may be formed on a film-forming substrate of glass, plastic, or the like of a sputtering target by sputtering.

As such a transparent conductive film, an ITO (Indium Tin Oxide) film having excellent light transmittance and conductivity is mainly used, and an ITO target is widely used to form the ITO film containing In, Sn, and O.

However, since the ITO film has a disadvantage of low moisture resistance and an increased resistance value due to moisture, studies have been made to use an IZO (Indium Zinc Oxide) film containing In, Zn, and O instead of the ITO film, and to use an IZO target to form the IZO film as the transparent conductive film.

However, in order to perform stable film formation, it is important that the density and the electric resistance of the target are uniform over the entire target, in addition to the high density and the low electric resistance of the sputtering target.

In particular, if the variation in volume resistivity in the thickness direction of the target is large, the mode characteristics change during sputtering, and also in a sputtering target composed of a plurality of blocks, variation in volume resistivity between the blocks is likely to occur, thereby impairing the quality stability of the entire target. Therefore, in the sputtering target, it is necessary to ensure uniformity of volume resistivity in the thickness direction. In the conventional IZO target, there is a problem that a stable IZO film cannot be formed because the volume resistivity in the thickness direction varies greatly.

In addition, the volume resistivity generally tends to be higher on the surface of the sintered body than in the interior of the sintered body constituting the sputtering target. However, even if the volume resistivity of the sintered body is not uniform in the thickness direction, it is considered that the uniformity of the volume resistivity can be secured to some extent by preparing the sputtering target by increasing the grinding amount of the surface of the sintered body. However, in this case, since it is necessary to increase the thickness of the sintered body and set the thickness according to an increase in the grinding amount, there is a concern that the density at the center in the thickness direction decreases or the yield of the product decreases due to an increase in the grinding amount.

Regarding such volume resistivity, patent document 1 describes that, in the production of a sputtering target containing at least indium oxide and zinc oxide, after the firing step, "the obtained sintered body is subjected to a reduction treatment in a reduction step preferably though it is an arbitrary step in order to make the volume resistance of the whole uniform".

Patent document 2 describes that the volume resistivity of an In — Sn — Zn — Al sputtering target having a high density and a low resistance is preferably 10m Ω cm or less, and that the cooling rate is set to 10 ℃/min or less, and further 5 ℃/min or less, for preventing the occurrence of cracks and obtaining a predetermined crystal form at the time of cooling after sintering In the production of the target.

Further, patent document 3 relates to an ITO target, not an IZO target, and discloses a sputtering target in which the difference in volume resistivity in the thickness direction of the target is 20% or less. Patent document 3 describes that, in order to reduce the difference in volume resistivity in the thickness direction of the target, the environment at the time of temperature reduction is mainly set to an atmospheric environment, and the average cooling rate is set to 0.1 to 3.0 ℃/min. Further, it was shown that there is a high correlation between the difference in volume resistivity in the sintered body and the difference in resistance of the thin film formed by using the target.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-68993

Patent document 2: japanese patent laid-open No. 2014-218706

Patent document 3: international publication No. 2014/156234

Disclosure of Invention

Problems to be solved by the invention

Patent document 1 does not describe any contents for reducing the variation in volume resistivity in the thickness direction. Further, even if the volume resistivity can be made uniform by performing the reduction treatment as a separate step after the firing, introduction of such a separate step is not desirable from the viewpoint of production because it leads to an increase in cost and an increase in man-hours.

Patent document 2 mentions that the volume resistivity is preferably low, but no consideration is given to variations in the volume resistivity in the thickness direction, and the description of the temperature lowering step is not intended to stabilize the volume resistivity.

Since patent document 3 relates to an ITO target instead of an IZO target, the proposed technique cannot be directly applied to an IZO target. In particular, in the IZO target, since a surface deterioration layer is present on the surface of the sintered body and the volume resistivity in the vicinity of the surface deterioration layer is further increased, unlike the ITO target, variation in the volume resistivity cannot be sufficiently reduced by the technique of the temperature lowering step described in patent document 3.

The present invention has been made to solve the above problems of the prior art, and an object of the present invention is to provide a sintered body capable of effectively suppressing variation in volume resistivity between the surface and the inside of the sintered body in an IZO target, a sputtering target, and a method for producing the same.

Means for solving the problems

In producing an IZO target, when a molded body formed into a predetermined shape is heated and sintered, oxygen sintering in which oxygen is introduced or atmospheric sintering is preferred in the temperature raising process in order to increase the density of the sintered body and realize excellent film characteristics. However, as a result of intensive studies, the inventors have found that when an atmosphere containing oxygen is introduced also during the temperature reduction process, the difference in volume resistivity in the thickness direction of the sputtering target is large as a result of the decrease in oxygen loss in the vicinity of the surface of the sintered body.

Therefore, it was found that, by providing the molded body in a nitrogen atmosphere or an argon atmosphere, which is different from the environment at the time of temperature reduction after heating and sintering, the reduction of oxygen loss in the vicinity of the surface of the sintered body can be suppressed, variation in volume resistivity in the thickness direction can be suppressed, and a sputtering target having more uniform volume characteristics can be manufactured.

Based on this finding, the sintered body of the present invention is a sintered body containing an oxide of In, Zn, and O, and the ratio of the difference between the volume resistivity Rs at a depth position of 1mm In the thickness direction from the surface of the sintered body and the volume resistivity Rd at a depth position of 4mm In the thickness direction from the surface of the sintered body divided by the volume resistivity Rd at the depth position of 4mm, that is, the absolute value of (Rs-Rd)/Rd is 20% or less In percentage.

Here, the absolute value of the ratio (Rs-Rd)/Rd is preferably 15% or less, and more preferably 10% or less, in terms of percentage.

The sintered body may contain Zn/(In + Zn) at 7 to 20 at%, preferably 10 to 17 at%.

The sputtering target of the present invention is a sputtering target comprising an oxide of In, Zn, and O, and the absolute value of (Rf-Ra)/Ra, which is the ratio of the difference between the volume resistivity Rf at a depth position of 0mm In the thickness direction from the surface of the sputtering target and the volume resistivity Ra at a depth position of 3mm In the thickness direction from the surface of the sputtering target divided by the volume resistivity Ra at the depth position of 3mm, is 20% or less In percentage.

Here, the absolute value of the ratio (Rf-Ra)/Ra is preferably 15% or less, and more preferably 10% or less, as represented by a percentage.

The sputtering target can be a sputtering target containing Zn/(In + Zn) at 7 to 20 at%, preferably 10 to 17 at%.

The method for manufacturing a sputtering target of the present invention includes: mixing powder raw materials containing indium oxide powder and zinc oxide powder and forming; the molded body thus obtained is sintered by heating, and the temperature of the sintered molded body is lowered in a nitrogen atmosphere or an argon atmosphere.

In this production method, the temperature decrease rate at the time of temperature decrease is preferably set to more than 1 ℃/min, more preferably 3 ℃/min.

In this production method, the molded body is preferably heated and sintered in the atmosphere or in an oxygen atmosphere.

Effects of the invention

According to the present invention, since the difference in volume resistivity between the surface and the inside of the sputtering target can be reduced, the change in film characteristics during sputtering is reduced, and a stable thin film can be formed. In addition, since the amount of grinding of the sintered body surface required for manufacturing a sputtering target of stable quality is reduced, the yield of the material can be improved.

Detailed Description

The embodiments of the present invention will be described in detail below.

A sintered body according to one embodiment of the present invention is a sintered body containing indium, zinc, and oxygen, and the absolute value of (Rs-Rd)/Rd, which is the ratio of the difference between the volume resistivity Rs at a depth position of 1mm in the thickness direction from the surface of the sintered body and the volume resistivity Rd at a depth position of 4mm in the thickness direction from the surface of the sintered body divided by the volume resistivity Rd at the depth position of 4mm, is 20% or less in percentage.

In addition, a sputtering target according to an embodiment of the present invention is a sputtering target including a sintered body containing indium, zinc, and oxygen. The ratio of the difference between the volume resistivity Rf at a depth position of 0mm in the thickness direction from the surface of the sputtering target (i.e., the surface position of the sputtering target) and the volume resistivity Ra at a depth position of 3mm in the thickness direction from the surface of the sputtering target divided by the volume resistivity Ra at the depth position of 3mm, i.e., the absolute value of (Rf-Ra)/Ra, is 20% or less in percentage.

(composition)

The sintered body constituting the sputtering target contains In, Zn and O, for example, In₂O₃(ZnO)_mThe amorphous oxide of (1). In the formula, m is an integer, and the value of m can be in the range of 3 to 20.

The zinc may be contained at 7 at% to 20 at%, typically 10 at% to 17 at%, as represented by the atomic ratio Zn/(In + Zn) of zinc. The amount of zinc can be appropriately changed according to the conductivity of the target film.

The contents of In, Zn, and the like can be measured by X-ray fluorescence analysis (XRF).

The sintered body may contain other elements In addition to In and Zn within a range not to impair the characteristics of the present invention. For example, when at least one element of Fe, Al, Si, Cu, and Pb is contained, the content of each element can be set to 100wtppm or less. When at least one element of Sn and Zr is contained, the content of each element can be set to 1000wtppm or less.

(volume resistivity)

In the embodiment of the sintered body, as described later, the ratio of the difference between the volume resistivity Rs of the surface (depth position of 1 mm) ground and exposed by 1mm in the thickness direction from the surface of the sintered body obtained by heat sintering and temperature reduction and the volume resistivity Rd of the surface (depth position of 4 mm) ground and exposed by 4mm in the thickness direction from the surface of the sintered body divided by the volume resistivity Rd of the target surface at the depth position of 4mm, that is, the absolute value of (Rs-Rd)/Rd is 20% or less in percentage.

If the ratio (Rs-Rd)/Rd exceeds 20%, the film characteristics in sputtering when the sintered body is used as a sputtering target change, and stable film formation cannot be performed, so that the sintered body surface needs to be ground a large amount in order to be used as a sputtering target. As a result, in order to manufacture a sputtering target having a predetermined thickness, it is necessary to predict the grinding amount in advance and prepare a sintered body having a large thickness.

Therefore, from this viewpoint, the ratio of (Rs-Rd)/Rd is more preferably 15% or less, and particularly preferably 10% or less.

In the embodiment of the sputtering target, it is preferable that the absolute value of (Rf-Ra)/Ra, which is a ratio obtained by dividing the difference between the volume resistivity Rf of the surface (0mm depth position) of the sputtering target obtained by polishing the sintered body and the volume resistivity Ra of the surface (3mm depth position) exposed by grinding 3mm in the thickness direction from the surface of the sputtering target by the volume resistivity Ra at the 3mm depth position, is 20% or less in percentage.

This enables stable film formation during sputtering. In other words, if the ratio exceeds 20%, film formation is unstable because film characteristics change with a decrease in thickness during sputtering.

The ratio (Rf-Ra)/Ra is preferably 15% or less, more preferably 10% or less.

The measurement of the volume resistivity of the sintered body or the sputtering target can be performed for the following planes. A polished surface was obtained from a grinding member of fine polishing powder having a grain size of #400 specified in JIS R6001(1998) at a grinding thickness of 0.2 mm.

The volume resistivity can be measured by a four-probe method described in JIS 1637. More specifically, the measurement was performed at 5 places in total of four corner regions and a central region, which were nine-divided by 3 × 3 in the longitudinal and lateral directions of the measurement surface of the sintered body or the sputtering target. The average of the 5-place measurements can be taken as the volume resistivity of the present invention. The measurement point can be, for example, the center of each region.

(Crystal particle size)

By setting the above-described difference in electrical resistance in the thickness direction, the difference between the size Ds of crystal grains of the structure obtained by grinding a surface of 1mm from the surface and the size Dd of crystal grains of a surface of 4mm from the surface (for example, a surface at the center in the thickness direction) can be set to 20% or less. The size of the crystal grains was observed at 4 arbitrary positions selected from the 5mm angle of the center of the target surface. Then, the average value of the crystal grain sizes was obtained from the 300-magnification SEM image photograph by the encoder method. The difference in crystal grain is obtained by comparing a surface ground to 1mm from the surface and a surface ground to 4mm from the surface (for example, a surface at the center of the thickness), and the absolute value of the relative difference (Ds-Dd)/Dd in the respective sizes is defined as the difference in crystal grain size.

The sintered body constituting the sputtering target can have an average crystal grain size of, for example, 1.0 to 5.0 μm, preferably 2.0 to 3.0 μm. The crystal grain size can be measured by cutting a part of the sintered body and mirror polishing the cut surface, and observing the SEM image.

(Density)

The relative density of the sintered body and the sputtering target can be 95% or more, preferably 98% or more.

In particular, in the present invention, the polishing amount in the production of a sputtering target from a sintered body can be reduced by reducing the variation in volume resistivity in the thickness direction, and therefore the density at the center position in the thickness direction can also be increased. In other words, if the variation in volume resistivity in the thickness direction is large, the polishing amount in the production of the sputtering target is expected to be large, and it is necessary to produce a thick sintered body in advance. However, in this case, since the thickness is large, heat is hardly conducted to the vicinity of the center in the thickness direction during heat sintering, and the density of the center position in the thickness direction of the obtained sintered body or sputtering target is lowered.

The relative density can be calculated from a theoretical density calculated from the density of the raw material powder and the density of the sintered body measured by the archimedes method by the following formula: relative density ═ density measured by archimedes method ÷ (theoretical density) × 100 (%). The theoretical density of IZO 10.7% was 7.00g/cm³。

(production method)

The sintered body and the sputtering target described above can be produced, for example, by the following methods.

First, for example, a raw material powder containing at least indium oxide powder and zinc oxide powder is mixed with a molding binder as necessary.

Subsequently, the mixed powder raw materials are filled into a mold and press-molded to prepare a molded body having a predetermined shape. Here, for example, 400 to 1000kgf/cm may be used²The pressure of (3) is applied for 1 to 3 minutes.

The molded body is then sintered in a sintering furnace, for example, by heating to a temperature of 1350 to 1500 ℃. The holding time of the heating temperature can be 1 hour to 100 hours, preferably 5 hours to 30 hours. In order to obtain a sputtering target having a high density and excellent film characteristics, the heat sintering is preferably performed in an oxidizing atmosphere such as the atmosphere or an oxygen atmosphere.

It is important to cool the sintered body not in the atmosphere or in the oxygen atmosphere but in the nitrogen atmosphere or in the argon atmosphere. By cooling in a nitrogen atmosphere, the reduction of oxygen loss in the vicinity of the surface of the sintered body is suppressed, and the variation in volume resistivity in the thickness direction of the sintered body can be suppressed to the above-described extent. In other words, when the temperature is lowered in the atmospheric environment or the oxygen environment, the oxygen loss in the vicinity of the surface is reduced, and the volume resistivity in the thickness direction largely varies and becomes uneven.

In order to further obtain the effect of suppressing the reduction of the oxygen loss, the temperature decrease rate after the heat sintering is preferably a rate exceeding 1 ℃/min, more preferably a rate exceeding 3 ℃/min, and particularly preferably a rate exceeding 5 ℃/min. This further suppresses variation in volume resistivity of the sintered body in the thickness direction, and enables the production of a sintered body having a more uniform volume resistivity.

The temperature can be reduced by, for example, introducing cold air, preferably nitrogen gas or argon gas, into the sintering furnace after the temperature is adjusted.

The temperature reduction rate in the above-mentioned environment is preferably at least 1400 ℃ to 1000 ℃ and natural temperature reduction can be carried out even at a temperature of less than 1000 ℃. This is because, in the IZO target, the volume characteristics are greatly affected by the cooling rate and the cooling environment in the high-temperature region in particular.

The sintered body obtained after the temperature reduction is ground on one surface by a known method such as mechanical grinding or chemical grinding in the thickness direction of the sintered body to a thickness of, for example, 1% to 20%, preferably 1% to 10%. Specifically, the grinding amount may be, for example, 0.1mm to 2.0mm, preferably 0.1mm to 1.0mm in the thickness direction of the sintered body. However, the grinding amount in the production of the sputtering target is not limited to this range, and may be any amount. This grinding can be performed using a grinding member of a fine powder for polishing having a grain size of #80 specified in JIS R6001 (1998).

In this embodiment, as described above, since the variation in volume resistivity in the thickness direction is small, the required grinding amount becomes small. This improves the yield of the material.

Examples

Next, a sputtering target was produced by trial production according to the present invention, and the performance thereof was confirmed, and therefore, the following description will be given. However, the description herein is for the purpose of example only, and is not limited thereto.

Indium oxide powder and zinc oxide powder were mixed and pulverized in the respective compositions shown in Table 1, and the mixture was put into a mold so as to have a composition of 800kgf/cm²The pressure of (3) was applied for 1 minute to obtain a molded article. The molded body was heated to 1400 ℃ in an electric furnace, held for 10 hours, sintered, and then cooled.

Here, the temperature reduction after the heat sintering was performed in a nitrogen atmosphere in examples 1 to 7, and in an atmospheric atmosphere in comparative examples 1 to 5. In examples 1 to 7 and comparative examples 1 to 5, as shown in table 1, the temperature rise, the holding environment, and the temperature decrease rate during heating and sintering were changed. The cooling rate shown in Table 1 is a rate between 1400 ℃ and 1000 ℃ and the temperature is naturally cooled when the temperature is reduced to less than 1000 ℃.

With respect to the sintered body thus obtained, a sputtering target was prepared by manually grinding 1mm in the thickness direction from the surface of the sintered body using sandpaper of fine powder for grinding of # 80. Further, the surface of the sintered body was finally ground to about 5mm by the same grinding method, and at each depth position in the middle, the volume resistivity was measured using a resistivity measuring instrument (model:. sigma. -5+) manufactured by NPS corporation, and the volume resistivity Rs at a depth position of 1mm from the surface of the sintered body, the volume resistivity Rd at a depth position of 4mm from the surface of the sintered body, and the volume resistivity Rb at the surface of the sintered body were measured, respectively. Before each volume resistivity was measured, the measured surface was manually ground to a finish thickness of 0.2mm using #400 sandpaper of fine polishing powder. Further, using these data, the ratio of the difference between Rs and Rd (Rs-Rd)/Rd × 100, and the ratio of the difference between Rb and Rd (Rb-Rd)/Rd × 100 were calculated, respectively. The results are shown in table 1.

In this example, the volume resistivity Rs at a depth position of 1mm from the surface of the sintered body is equal to the volume resistivity Rf at a depth position of 0mm from the surface of the sputtering target. The volume resistivity Rd at a depth position of 4mm from the surface of the sintered body was equal to the volume resistivity Ra at a depth position of 3mm from the surface of the sputtering target.

In table 1, "the maximum value (%) of the difference ratio" is a ratio of calculating the difference between the maximum and minimum of the volume resistance measured at each depth position before reaching the depth position of about 5 mm. The "grinding amount (mm) at which 20% is confirmed" means a grinding amount at which 20% is obtained as the volume resistance ratio based on the volume resistivity at the depth position of 4mm in the grinding amount changes from the surface to the depth.

In addition, when the crystal grains in example 1 were measured, the polished surface at a distance of 1mm from the surface of the sintered body was 2.45 μm, the polished surface at a distance of 4mm was 2.59 μm, and the absolute value of the relative difference (Ds-Dd)/Dd was 5.4%.

[ Table 1]

As shown in table 1, in examples 1 to 7 in which the temperature reduction atmosphere was made nitrogen, the ratio of the difference between the volume resistivity Rs at the 1mm depth position of the sintered body and the volume resistivity Rd at the 4mm depth position of the sintered body was 20% or less regardless of the temperature rise and the atmosphere for holding, and the volume resistivity reduction and the variation were suppressed, regardless of the composition.

In particular, in examples 3 and 6 in which temperature reduction was performed at a high speed exceeding 5 ℃/min, further reduction in volume resistivity and suppression of variation were achieved.

In contrast, in comparative examples 1 to 5, after the molded body was heat-sintered, the temperature was reduced in the atmospheric environment, and the ratio of the difference between the volume resistivity Rs at the 1mm depth position of the sintered body and the volume resistivity Rd at the 4mm depth position of the sintered body exceeded 20%, which was considerably large, and the sintered body had large variation in volume resistivity.

As described above, according to the present invention, it is possible to effectively suppress the variation in volume resistivity between the surface and the inside of the sintered body.

Claims

1. A sintered body comprising an oxide of In, Zn, O, containing 7 at% to 20 at% of Zn/(In + Zn), wherein the ratio of the difference between the volume resistivity Rs at a depth position of 1mm In the thickness direction from the surface of the sintered body and the volume resistivity Rd at a depth position of 4mm In the thickness direction from the surface of the sintered body divided by the volume resistivity Rd at the depth position of 4mm, that is, the absolute value of (Rs-Rd)/Rd, is 20% or less In percentage.

2. The sintered body of claim 1, wherein the ratio, the absolute value of (Rs-Rd)/Rd, expressed as a percentage is 15% or less.

3. The sintered body of claim 1, wherein the ratio, the absolute value of (Rs-Rd)/Rd, expressed as a percentage is 10% or less.

4. The sintered body as claimed In any one of claims 1 to 3, wherein Zn/(In + Zn) is contained at 10 to 17 at%.

5. The sintered body according to any one of claims 1 to 3, wherein a ratio of a difference between a size Ds of crystal grains of a surface ground by 1mm in a thickness direction from the surface of the sintered body and a size Dd of crystal grains of a surface ground by 4mm in the thickness direction from the surface of the sintered body divided by a size Dd of crystal grains of the surface ground by 4mm, that is, an absolute value of (Ds-Dd)/Dd is 20% or less in percentage.

6. The sintered body as claimed in any one of claims 1 to 3, wherein the sintered bodyContaining In of the formula₂O₃(ZnO)_mAn amorphous oxide represented by (1), wherein m is 3. ltoreq. m.ltoreq.20.

7. The sintered body as claimed in any one of claims 1 to 3, further comprising 100wtppm or less of at least one element selected from Fe, Al, Si, Cu and Pb, and 1000wtppm or less of at least one element selected from Sn and Zr.

8. The sintered body as claimed in any one of claims 1 to 3, wherein the average crystal grain diameter is 1.0 to 5.0 μm.

9. The sintered body as claimed in any one of claims 1 to 3, wherein the relative density is 95% or more.

10. A sputtering target comprising an oxide of In, Zn and O, wherein the sputtering target contains 7 to 20 at% of Zn/(In + Zn), and the absolute value of (Rf-Ra)/Ra, which is the ratio of the difference between the volume resistivity Rf at a depth position of 0mm In the thickness direction from the surface of the sputtering target and the volume resistivity Ra at a depth position of 3mm In the thickness direction from the surface of the sputtering target divided by the volume resistivity Ra at the depth position of 3mm, is 20% or less In percentage.

11. A sputtering target according to claim 10, wherein the ratio, i.e. the absolute value of (Rf-Ra)/Ra, is 15% or less expressed as a percentage.

12. A sputtering target according to claim 10, wherein the ratio, i.e. the absolute value of (Rf-Ra)/Ra, is 10% or less expressed as a percentage.

13. A sputter target according to any one of claims 10 to 12, whereby the sputter target contains 10 to 17 at% Zn/(In + Zn).

14. According to claims 10E12, wherein the sputtering target comprises In of the general formula₂O₃(ZnO)_mAn amorphous oxide represented by (1), wherein m is 3. ltoreq. m.ltoreq.20.

15. The sputtering target according to any one of claims 10 to 12, further comprising 100wtppm or less of at least one element selected from Fe, Al, Si, Cu and Pb, and 1000wtppm or less of at least one element selected from Sn and Zr.

16. The sputtering target according to any one of claims 10 to 12, wherein the average crystal grain diameter is 1.0 μm to 5.0 μm.

17. A sputtering target according to any one of claims 10 to 12, wherein the relative density is 95% or more.

18. A method for producing a sputtering target according to any one of claims 10 to 17, comprising:

mixing and molding powder raw materials containing indium oxide powder and zinc oxide powder, and heating and sintering a molded body obtained by the molding;

the temperature reduction of the formed body after heating and sintering is carried out in a nitrogen environment or an argon environment,

a sputtering target containing Zn/(In + Zn) at 7 to 20 at% is produced.

19. The method for manufacturing a sputtering target according to claim 18, wherein the temperature decrease rate at the time of temperature decrease is a rate exceeding 1 ℃/min.

20. The method for manufacturing a sputtering target according to claim 18, wherein the temperature decrease rate at the time of temperature decrease is a rate exceeding 3 ℃/min.

21. The method for producing a sputtering target according to any one of claims 18 to 20, wherein the heating and sintering of the molded body is performed in an atmosphere or an oxygen atmosphere.

22. The method for producing a sputtering target according to any one of claims 18 to 20, wherein the powder raw materials are mixed and molded so that 400 to 1000kgf/cm is used²The pressure of (3) is applied for 1 to 3 minutes.

23. The method for producing a sputtering target according to any one of claims 18 to 20, wherein the compact is heated at 1350 ℃ to 1500 ℃ for 1 hour to 100 hours when the compact is heated and sintered.