TW202342791A - sputtering target - Google Patents

Abstract

A sputtering target according to the present invention is formed by using a bonding material to bond a plurality of sputtering target members to a substrate. The sputtering target members are composed of oxides containing indium (In), zinc (Zn), and an additional element (X), with the additional element (X) being at least one element selected from among tantalum (Ta) and niobium (Nb), such that the atomic ratios for the respective elements satisfy prescribed relationships. The sintering target has substrate protecting members positioned in the gaps formed between the plurality of sputtering target members.

Description

sputtering target

The invention relates to a sputtering target.

In the technical field of thin film transistors (hereinafter also referred to as "TFT") used in flat panel displays (hereinafter also referred to as "FPD"), as FPDs become more functional, In-Ga-Zn composite oxides (hereinafter also referred to as Oxide semiconductors represented by "IGZO" (called "IGZO") have gradually attracted attention and become practical instead of the previous amorphous silicon. IGZO has the advantages of exhibiting higher field effect mobility and lower leakage current. In recent years, as FPDs become more highly functional, a material that exhibits a higher field effect mobility than that exhibited by IGZO is expected.

For example, Patent Documents 1 and 2 propose an oxide semiconductor for TFT made of an In-Zn-X composite oxide containing an indium (In) element, a zinc (Zn) element, and an optional element X. According to this document, the oxide semiconductor is formed by sputtering using a target containing an In-Zn-X composite oxide.

Furthermore, regarding the oxide semiconductor sputtering target used for sputtering, the material is ceramic, so it is difficult to construct a large-area target with one target material. Therefore, a large-area oxide semiconductor sputtering target is manufactured by preparing a plurality of targets having a certain size and bonding them to a base material having a required area (see, for example, Patent Document 3).

The base material of the sputtering target usually uses Cu, Ti, SUS, etc., and a bonding material with good thermal conductivity, such as In and other metals, is used to join the base material and the target material. For example, when manufacturing a large oxide semiconductor sputtering target, a large Cu flat plate base material or a Ti cylindrical base material is prepared, and a plurality of targets joined to the base material are prepared. Then, a plurality of targets are arranged on the base material, and the targets are bonded to the base material through a bonding material of In-based or Sn-based metal. When performing this bonding, taking into account the difference in thermal expansion between the base material and the target material, the adjacent target materials are arranged so that a gap of 0.1 mm to 1.0 mm appears at room temperature. Prior technical literature patent documents

Patent document 1: US2013/270109 Patent Document 2: Publication No. US2014/102892 Patent document 3: WO2012/063524

When a sputtering target formed by joining a plurality of targets is used to form a thin-film semiconductor element by sputtering, the following problems may arise: Cu or Cu as a constituent material of the base material during sputtering may occur. Ti is also sputtered from the gap between the target materials and mixed into the film. Although the mixing of Cu or Ti in the thin film is at the level of several ppm, its impact on oxide semiconductors is extremely great. For example, if a semiconductor element containing Cu or Ti is formed near the gap between the target and other parts When compared with semiconductor devices, the field effect mobility of TFT devices shows a decreasing trend, and the ON/OFF ratio also shows a decreasing trend. In order to promote the large-area sputtering target, this kind of bad situation is also a problem that should be eliminated.

An object of the present invention is to provide a sputtering target which, although it is a large-area sputtering target obtained by joining a plurality of target materials, can effectively prevent the constituent materials of the base material from being mixed into the thin film being formed.

The inventors of the present invention conducted diligent research in order to solve the above-mentioned problems, and found that by arranging the base material protective member in the gap formed between a plurality of sputtering targets, the constituent materials of the base material are not sputtered, but can be sputtered. It can effectively prevent the constituent materials from being mixed into the film being formed.

That is, the present invention provides a sputtering target formed by joining a plurality of sputtering targets to a base material using a joining material, and the plurality of sputtering targets contain an element including indium (In) and zinc (Zn). Oxides of elements and added elements (X), The additional element (X) includes at least one element selected from tantalum (Ta) and niobium (Nb), The atomic ratio of each element satisfies formulas (1) to (3) at the same time (X in the formula is set to the sum of the content ratios of the above-mentioned added elements), 0.4≦(In＋X)/(In＋Zn＋X)＜0.75 (1) 0.25＜Zn/(In＋Zn＋X)≦0.6     (2) 0.001≦X/(In＋Zn+X)≦0.015    (3) This sputtering target has a base material protective member arranged in a gap formed between the plurality of sputtering targets.

Hereinafter, the preferred embodiments of the present invention will be described. In addition, "～" indicating a numerical range is used to include the numerical values described before and after it as the lower limit and upper limit. Unless otherwise specified, "～" will be used with the same meaning below.

The present invention relates to a sputtering target (hereinafter also referred to as "target"). The sputtering target used in the target of the present invention (hereinafter also referred to as "target") contains an oxide containing an indium (In) element, a zinc (Zn) element, and an additive element (X). The additional element (X) includes at least one element selected from tantalum (Ta) and niobium (Nb). The target material of the present invention contains In, Zn and the additive element (X) as its constituent metal elements. It may also contain In, Zn and the additive element (X) in addition to these elements, deliberately or unavoidably, within the scope that does not impair the effect of the present invention. Trace elements. Examples of trace elements include elements contained in the organic additives described below or media materials such as ball mills that are mixed during target production. Examples of trace elements in the target material of the present invention include: Fe, Cr, Ni, Al, Si, W, Zr, Na, Mg, K, Ca, Ti, Y, Ga, Sn, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sr and Pb, etc. Relative to the total mass of the oxides including In, Zn, and ppm or less, and more preferably 50 ppm or less. The total amount of these trace elements is preferably 500 ppm or less, more preferably 300 ppm or less, and still more preferably 100 ppm or less. When the target material of the present invention contains trace elements, the above-mentioned total mass also includes the mass of the trace elements.

The target material of the present invention is preferably composed of a sintered body containing the above-mentioned oxide. The shapes of the sintered body and the sputtering target are not particularly limited, and previously known shapes can be used, such as flat plates and cylindrical shapes.

In order to improve the performance of the oxide semiconductor device formed from the target material of the present invention, it is preferable that the atomic ratio of the metal elements constituting the target material, namely In, Zn and X, is within a specific range.

Specifically, In and ). 0.4≦(In+X)/(In+Zn+X)<0.75 (1) Zn preferably satisfies the atomic ratio represented by the following formula (2). 0.25＜Zn/(In＋Zn＋X)≦0.6     (2) X preferably satisfies the atomic ratio represented by the following formula (3). 0.001≦X/(In＋Zn＋X)≦0.015     (3)

By making the atomic ratios of In, Zn and Efficient mobility, low leakage current and critical voltage close to 0 V. From the viewpoint of making these advantages more remarkable, In and X further preferably satisfy the following formulas (1-2) to (1-5). 0.43≦(In+X)/(In+Zn+X)≦0.74 (1-2) 0.48≦(In+X)/(In+Zn+X)≦0.73 (1-3) 0.53≦(In+X)/(In+Zn+X)≦0.72 (1-4) 0.58≦(In＋X)/(In＋Zn＋X)≦0.70 (1-5)

From the same viewpoint as above, it is further preferred that Zn satisfies the following formulas (2-2) to (2-5), and X further preferably satisfies the following formulas (3-2) to (3-5). .

0.26≦Zn/(In＋Zn+X)≦0.57    (2-2) 0.27≦Zn/(In+Zn+X)≦0.52 (2-3) 0.28≦Zn/(In+Zn+X)≦0.47 (2-4) 0.30≦Zn/(In+Zn+X)≦0.42 (2-5) 0.0015≦X/(In＋Zn+X)≦0.013    (3-2) 0.002＜X/(In＋Zn＋X)≦0.012 (3-3) 0.0025≦X/(In＋Zn＋X)≦0.010 (3-4) 0.003≦X/(In＋Zn＋X)≦0.009 (3-5)

As described above, one or more types selected from Ta and Nb are used as the additional element (X). These elements can be used individually or in combination. In particular, from the viewpoint of the overall performance of the oxide semiconductor device produced from the target material of the present invention and the economical aspect of producing the target material, it is preferable to use Ta as the additive element (X).

In order to further improve the field-effect mobility of the oxide semiconductor device formed from the target material of the present invention and to exhibit a critical voltage close to 0 V, the target material of the present invention is preferably one that satisfies the above (1) In addition to the relationship (3), the atomic ratio of In and X also satisfies the following formula (4). 0.970≦In/(In＋X)≦0.999(4)

From equation (4), it can be seen that in the target material of the present invention, by using a very small amount of X relative to the amount of In, the field effect mobility of the oxide semiconductor element formed from the target material is improved. This situation was discovered for the first time by the present inventor. In the prior art known so far (for example, the prior art described in Patent Documents 1 and 2), the amount of X used relative to the amount of In is larger than in the present invention.

From the perspective of further improving the field-effect mobility of the oxide semiconductor formed from the target material and exhibiting a critical voltage close to 0 V, the atomic ratio of In and ) to (4-4). 0.980≦In/(In＋X)≦0.997 (4-2) 0.990≦In/(In＋X)≦0.995 (4-3) 0.990＜In/(In＋X)≦0.993 (4-4)

From the perspective of making the FPD highly functional because the TFT element, which is an oxide semiconductor element, has good transmission characteristics, it is preferable that the field effect mobility of the oxide semiconductor element formed from a target material is large. Specifically, the field effect mobility (cm ² /Vs) of a TFT having an oxide semiconductor element formed of a target material is preferably 45 cm ² /Vs or more, more preferably 50 cm ² /Vs or more, and still more preferably 60 cm ² /Vs or more, more preferably 70 cm ² /Vs or more, more preferably 80 cm ² /Vs or more, more preferably 90 cm ² /Vs or more, particularly preferably 100 cm ² /Vs or more . The larger the value of the field effect mobility, the better in terms of high functionality of the FPD. If the field effect mobility is as high as about 200 cm ² /Vs, sufficiently satisfactory performance can be obtained.

The ratio of each metal contained in the target material of the present invention is measured, for example, by ICP (Inductively Coupled Plasma, inductively coupled plasma) emission spectrometry.

The so-called "base material protective member disposed in the gap formed between a plurality of sputtering targets" in the present invention refers to a member that covers the surface of the base material exposed from the gap between the plurality of sputtering targets bonded to the base material, and has an The effect of substances that adversely affect the formed film from the gap during sputtering. As such a base material protective member, a strip-shaped base material protective member can be disposed on the surface of the base material, or the substance to be the base material protective member can be formed into a film or sheet by coating, plating, sputtering, thermal spraying, etc. It is arranged on the surface of the substrate in a shape or strip. Furthermore, the base material protective member may also be disposed to fill the above-mentioned gaps. Alternatively, a part of the planar member may be protruded, and the protruding part may fill the gap. In the present invention, it is particularly preferable that the substrate protective member is provided with a belt.

As the material of such a substrate protective member, substances that do not have adverse effects even if mixed into the thin film to be formed can be used, such as all or a part of the elements constituting the target material, alloys containing these elements, or Oxides etc.

Furthermore, regarding the material of the above-mentioned base material protective member, the chemical composition of the material is substantially different from the chemical composition of the bonding material used for bonding to the base material. For example, when metal indium is used as a bonding material, it means that the base material protection member at this time is not metal indium. In addition, metal indium used as a bonding material may remain in the gap between the targets, and when the indium remaining in the gap solidifies, the surface may be oxidized. In this way, when the metal indium used for the bonding material is solidified in the gap, it is difficult to form a uniform oxide film on the surface of the indium, so the effect as the substrate protective member of the present invention cannot be exerted.

The sputtering target in the present invention is, for example, a plate-shaped or cylindrical target. A plate-shaped sputtering target is one in which a plurality of plate-shaped targets are arranged on the plane of a plate-shaped base material and joined together. Moreover, regarding a cylindrical sputtering target, a plurality of cylindrical targets are embedded or inserted into a cylindrical base material and are arranged in a multi-stage shape in the direction of the cylindrical axis of the cylindrical base material. Those obtained by bonding, or those obtained by arranging a plurality of curved targets obtained by longitudinally cutting a hollow cylinder in the direction of the cylinder axis in the circumferential direction and bonding them on the outer side of the cylindrical base material. The plate-shaped or cylindrical sputtering target is often used in large-area sputtering equipment. Furthermore, the present invention can also be applied to sputtering targets of other shapes, and the shape of the target material is not limited.

The substrate protective member in the present invention is preferably any one of Zn, Ta, and Nb, or an alloy containing any two or more of In, Zn, Ta, and Nb, or an alloy containing In, Zn, Ta, And ceramics containing any one or more of Nb. If this kind of metal or ceramic is used as a substrate protective member, even if a trace amount is mixed into the formed oxide semiconductor film, the impact on the characteristics of the TFT element can be reduced compared with Cu or Ti, etc. Furthermore, examples of ceramic materials include oxides, nitrides, nitrogen oxides, etc. containing any one or more of In, Zn, Ta, and Nb. Since the target material is an oxide, ceramic materials are preferred. Also an oxide. Specific examples of ceramic materials include: In ₂ O ₃ , ZnO, Ta ₂ O ₅ , Nb ₂ O ₅ , In-Zn oxide, In-Ta oxide, In-Nb oxide, Zn-Ta oxide, Zn-Nb oxide, Zn-Ta-Nb oxide, In-Zn-Ta oxide, In-Zn-Nb oxide, In-Zn-Ta-Nb oxide, etc., or InN, Zn ₃ N ₂ , TaN , NbN, In-Zn nitride, In-Ta nitride, In-Nb nitride, Zn-Ta nitride, Zn-Nb nitride, Zn-Ta-Nb nitride, In-Zn-Ta nitride, In - Zn-Nb nitride, In-Zn-Ta-Nb nitride, etc., but are not limited to these.

Furthermore, when the base material protective member contains the metal, alloy or ceramic as mentioned above, it is preferably 90 mass% or more, more preferably 95 mass% or more, further preferably 99 mass% or more, and still more Preferably it is 99.5% by mass or more, particularly preferably it is 99.9% by mass or more, and most preferably it is 99.95% by mass or more and contains these as the main material.

When the metal or ceramic constituting the base material protective member is in a film-like, sheet-like or strip-like shape as described above, the thickness of the base material protective member is preferably 0.0001 mm to 1.0 mm. The width of the substrate protective member is preferably the same as or wider than the gap formed between the target members, and is preferably 5.0 mm to 30 mm wide. In addition, when the base material protective member having the above-mentioned shape is arranged on the base material, it can be attached using a target bonding material, conductive double-sided tape, or the like.

The base material protective member in the present invention may have a structure in which a first base material protective member and a second base material protective member are laminated. The sputtering target of the present invention can be easily produced by having such a structure in which the base material protective members are laminated. The first base material protective member and the second base material protective member can be appropriately selected and applied according to the material of the target or the base material. material. The widths of the first substrate protective member and the second substrate protective member may be the same or different. Furthermore, the base material protective member of the laminated structure is arranged along the gap formed between the targets in a state where the first base material protective member is on the target side and the second base material protective member is on the base material side.

When the base material protective member in the present invention is provided in a laminated structure, a first base material protective member with a narrow width and a second base material protective member with a wide width can be laminated, and the second base material protective member can be laminated. A structure in which the members are exposed on both end sides of the first base material protective member. This structure is a structure in which a first base material protective member with a narrow width is laminated on a second base material protective member with a wide width.

When the base material protective member in the present invention has a laminated structure and is formed into a film-like, sheet-like or strip-like shape, the thickness of the first base material protective member is preferably 0.0001 mm to 0.3 mm, and the thickness of the second base material protective member is preferably 0.0001 mm to 0.3 mm. The thickness of the substrate protective component is preferably 0.1 mm to 0.7 mm. The total thickness of the first base material protective member and the second base material protective member is preferably 0.3 mm to 1.0 mm. Moreover, when the first base material protective member and the second base material protective member with the same width are laminated, the width of these base material protective members is preferably 5 mm to 30 mm. Furthermore, when laminating a first base material protective member with a narrow width and a second base material protective member with a wide width, the width of the first base material protective member is preferably the same as the gap formed between the target members. Or it may be wider than this gap. Considering workability, etc., it is preferably 5 mm to 20 mm. The width of the wider second base material protective member is preferably 3 mm to 10 mm wider than the width of the first base material protective member.

When the base material protective member in the present invention has the above-mentioned laminated structure, it is preferable that the second base material protective member is Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb , Mo, Ag, and Ta, or an alloy containing any two or more of them. Furthermore, it is preferable that it is made of any one metal among Zn, Ta, and Nb, or an alloy containing any two or more of In, Zn, Ta, and Nb, or an alloy containing any one of In, Zn, Ta, and Nb. The above ceramic forms the first base material protective member.

When the base material protective member in the present invention has the above-mentioned laminated structure, it is preferable that the first base material protective member is formed from a ceramic containing at least one of In, Zn, Ta, and Nb. The reason is that these ceramics have the same composition as the target member, or a part of the composition is the same as the target material. Therefore, even if they are mixed into the film during film formation, they have little impact on the TFT element characteristics. Furthermore, examples of ceramics include oxides, nitrides, nitrogen oxides, and the like containing any one or more of In, Zn, Ta, and Nb. Since the target material is an oxide, ceramics and oxides are preferred. . Specific examples of ceramics include: In ₂ O ₃ , ZnO, Ta ₂ O ₅ , Nb ₂ O ₅ , In-Zn oxide, In-Ta oxide, In-Nb oxide, Zn-Ta oxide, Zn -Nb oxide, Zn-Ta-Nb oxide, In-Zn-Ta oxide, In-Zn-Nb oxide, In-Zn-Ta-Nb oxide, etc., or InN, Zn ₃ N ₂ , TaN, NbN, In-Zn nitride, In-Ta nitride, In-Nb nitride, Zn-Ta nitride, Zn-Nb nitride, Zn-Ta-Nb nitride, In-Zn-Ta nitride, In- Zn-Nb nitride, In-Zn-Ta-Nb nitride, etc., but are not limited to these.

Furthermore, when the second base material protective member contains the metal or alloy as described above, it is preferably 90 mass% or more, more preferably 95 mass% or more, further preferably 99 mass% or more, and still more Preferably it is 99.5% by mass or more, particularly preferably it is 99.9% by mass or more, and most preferably it is 99.95% by mass or more and contains these as the main material. Moreover, when the first base material protective member contains the metal, alloy or ceramic as described above, it is preferably 90 mass% or more, more preferably 95 mass% or more, further preferably 99 mass% or more, and further It is more preferable that it contains 99.5 mass % or more, especially preferably 99.9 mass % or more, and most preferably 99.95 mass % or more, and it contains these as a main material.

Furthermore, when ceramics are used in the first base material protective member, it can also be applied by using evaporation method, sputtering method, plasma spraying method, cold spraying method, aerosol deposition method, coating method, etc. These ceramics form a first substrate protective member and are used in the present invention.

In addition to the atomic ratios of In, Zn and X, the target material of the present invention is also characterized by its high relative density. Specifically, the target material of the present invention has a relative density that is preferably a relatively high value of 95% or more. By displaying such a relatively high relative density, when the target material of the present invention is used for sputtering, the generation of particles can be suppressed, which is preferable. From this point of view, the relative density of the target material of the present invention is more preferably 97% or more, further preferably 98% or more, still more preferably 99% or more, particularly preferably 100% or more, and particularly preferably more than 100%. . The target material of the present invention having such a relative density is suitably produced by the following method. Relative density is measured according to Archimedes' method. The specific measurement method will be described in detail in the following examples.

As mentioned above, the target material of the present invention contains an oxide containing In, Zn and X. The oxide may be an oxide of In, an oxide of Zn or an oxide of X. Alternatively, the oxide may be a composite oxide of any two or more elements selected from the group consisting of In, Zn and X. Specific examples of the composite oxide include: In-Zn composite oxide, Zn-Ta composite oxide, In-Ta composite oxide, In-Nb composite oxide, Zn-Nb composite oxide, In-Nb Composite oxide, In-Zn-Ta composite oxide, In-Zn-Nb composite oxide, etc., but are not limited to these.

From the viewpoint of increasing the density and strength of the target material and reducing the electrical resistance, the target material of the present invention is particularly preferably composed of an In ₂ O ₃ phase which is an oxide of In and Zn ₃ In which is a composite oxide of In and Zn. ₂ O ₆ phase. The target material of the present invention contains the In ₂ O ₃ phase and the Zn ₃ In ₂ O ₆ phase. Whether or not the target material is observed can be measured by X-ray diffraction (hereinafter also referred to as "XRD") using the target material of the present invention as an object. To judge the In ₂ O ₃ phase and Zn ₃ In ₂ O ₆ phase. Furthermore, the In ₂ O ₃ phase in the present invention may contain trace amounts of Zn element.

Specifically, in the XRD measurement using CuKα rays as the X-ray source, the main peak of the In ₂ O ₃ phase was observed in the range of 2θ=30.38° to 30.78°. The main peak of the Zn ₃ In ₂ O ₆ phase is observed in the range from 2θ=34.00° to 34.40°.

When the In ₂ O ₃ phase is observed in the target material of the present invention by XRD measurement, the In ₂ O ₃ phase is preferred in terms of increasing the density and strength of the target material of the present invention and reducing the resistance. The size of the grains satisfies a specific range. Specifically, the size of the crystal grains of the In ₂ O ₃ phase is preferably 3.0 μm or less, more preferably 2.7 μm or less, further preferably 2.5 μm or less. The smaller the size of the crystal grains, the better. The lower limit is not particularly limited, but is usually 0.1 μm or more.

When the Zn ₃ In ₂ O ₆ phase is observed in the target material of the present invention by XRD measurement, Zn ₃ In is preferred in terms of improving the density and strength of the target material of the present invention and reducing the resistance. The size of the crystal grains of the ₂ O ₆ phase also satisfies a specific range. Specifically, the size of the crystal grains of the Zn ₃ In ₂ O ₆ phase is preferably 3.9 μm or less, more preferably 3.5 μm or less, further preferably 3.0 μm or less, still more preferably 2.5 μm or less, still more preferably 2.3 μm or less, particularly preferably 2.0 μm or less, particularly preferably 1.9 μm or less. The smaller the size of the crystal grains, the better. The lower limit is not particularly limited, but is usually 0.1 μm or more.

In order to set the size of the crystal grains of the In ₂ O ₃ phase and the size of the crystal grains of the Zn ₃ In ₂ O ₆ phase within the above ranges, for example, the target material can be manufactured by the following method. The size of the crystal grains of the In ₂ O ₃ phase and the size of the crystal grains of the Zn ₃ In ₂ O ₆ phase are measured by observing the target material of the present invention using a scanning electron microscope (hereinafter also referred to as "SEM"). The specific measurement method will be described in detail in the following examples.

Next, a suitable manufacturing method of the target material of the present invention will be described. In this manufacturing method, an oxide powder as a raw material of a target material is molded into a predetermined shape to obtain a molded body, and the molded body is fired to obtain a target composed of a sintered body. To obtain shaped bodies, methods hitherto known in this technical field can be used. In terms of producing a dense target material, it is particularly preferable to use the casting molding method or the CIP (Cold Isostatic Pressing) molding method.

Casting forming method is also called slip forming method. When performing the casting molding method, a dispersion medium is first used to prepare a slurry containing raw material powder and organic additives.

As the raw material powder, it is preferable to use oxide powder or hydroxide powder. As the oxide powder, In oxide powder, Zn oxide powder, and X oxide powder are used. As the In oxide, In ₂ O ₃ can be used, for example. As the Zn oxide, ZnO can be used, for example. As the X oxide powder, for example, Ta ₂ O ₅ and Nb ₂ O ₅ can be used.

In this production method, these raw material powders are all mixed and then calcined. In contrast, in the conventional technology, for example, the technology described in Patent Document 2, In ₂ O ₃ powder and Ta ₂ O ₅ powder are mixed and then calcined, and then the obtained calcined powder and ZnO powder are mixed and then calcined again. Calcination. In this method, since calcination is performed in advance, the particles constituting the powder become coarse particles, making it difficult to obtain a target material with a high relative density. On the other hand, in the present production method, it is preferable to mix and shape all the In oxide powder, Zn oxide powder and X oxide powder at normal temperature and then calcine, so that the relative density can be easily obtained. Higher density target material.

The usage amounts of In oxide powder, Zn oxide powder and X oxide powder are preferably adjusted so that the atomic ratio of In, Zn and X in the target target satisfies the above range.

The particle size of the raw material powder is preferably 0.1 μm or more and 1.5 μm or less, expressed as the volume cumulative particle size D ₅₀ at 50 volume % of the cumulative volume obtained by laser diffraction scattering particle size distribution measurement. By using raw material powder with a particle size within this range, a target material with a relatively high density can be easily obtained.

The above-mentioned organic additives are substances used to appropriately adjust the properties of the slurry or the formed body. Examples of organic additives include binders, dispersants, plasticizers, and the like. Binders are added to improve the strength of the molded body. As the binder, a binder commonly used when obtaining a molded body by a known powder sintering method can be used. Examples of the binder include polyvinyl alcohol. The dispersant is added to improve the dispersibility of the raw material powder in the slurry. Examples of the dispersant include polycarboxylic acid dispersants and polyacrylic acid dispersants. Plasticizers are added to improve the plasticity of the molded body. Examples of the plasticizer include polyethylene glycol (PEG), ethylene glycol (EG), and the like.

The dispersion medium used when preparing a slurry containing raw material powder and organic additives is not particularly limited, and can be appropriately selected from water-soluble organic solvents such as water and alcohol according to the purpose. The method of preparing the slurry containing raw material powder and organic additives is not particularly limited. For example, the raw material powder, organic additives, dispersion medium and zirconia balls can be put into a tank and mixed in a ball mill.

After the slurry is obtained in this manner, the slurry is flowed into the mold, and then the dispersion medium is removed to produce a molded body. Examples of molds that can be used include metal molds, plaster molds, and resin molds that are pressurized to remove the dispersion medium.

On the other hand, in the CIP molding method, the same slurry as that used in the cast molding method is spray-dried to obtain dry powder. The obtained dry powder is filled into a mold for CIP molding.

After the shaped body is obtained in this manner, it is subsequently calcined. Calcination of the shaped body can usually be carried out in an oxygen-containing environment. In particular, it is easier to calcine in an atmospheric environment. The calcination temperature is preferably from 1200°C to 1600°C, more preferably from 1300°C to 1500°C, and further preferably from 1350°C to 1450°C. The calcination time is preferably from 1 hour to 100 hours, more preferably from 2 hours to 50 hours, and still more preferably from 3 hours to 30 hours. The temperature rise rate is preferably 5°C/hour or more and 500°C/hour or less, more preferably 10°C/hour or more and 200°C/hour or less, and still more preferably 20°C/hour or more and 100°C/hour or less.

In the calcination of the shaped body, from the viewpoint of promoting sintering and producing a dense target material, it is preferable to maintain a constant temperature during the calcination process in which a composite oxide of In and Zn, such as Zn ₅ In ₂ O ₈ , is produced. time. Specifically, when the raw material powder contains In ₂ O ₃ powder and ZnO powder, they react with each other as the temperature rises to produce a phase of Zn ₅ In ₂ O ₈ , which then becomes a phase of Zn ₄ In ₂ O ₇ . phase, and then becomes the phase of Zn ₃ In ₂ O ₆ . In particular, in terms of promoting densification by volume diffusion when the Zn ₅ In ₂ O ₈ phase is generated, it is preferable to reliably generate the Zn ₅ In ₂ O ₈ phase. From this point of view, during the temperature rise process of calcination, it is better to maintain the temperature in the range of above 1000°C and below 1250°C for a certain period of time, and more preferably to maintain the temperature in the range of above 1050°C and below 1200°C for a certain period of time. . The temperature maintained is not necessarily limited to the temperature at a specific point, but can also be a temperature range with a certain degree of amplitude. Specifically, when T (℃) is a specific temperature selected from the range of 1000°C to 1250°C, for example, it may be T±10°C, preferably T±5°C, and more preferably T±3. °C, and more preferably T±1 °C, as long as it is included in the range of 1000°C or more and 1250°C or less. The time to maintain this temperature range is preferably from 1 hour to 40 hours, and more preferably from 2 hours to 20 hours.

The target material obtained in this way can be processed into a specified size by grinding or the like. By bonding it to a base material, a sputtering target can be obtained. The sputtering target obtained in this manner is suitably used for manufacturing an oxide semiconductor. For example, in the manufacture of TFTs, the target material of the present invention can be used.

For example, as shown in FIG. 1 , the sputtering target of the present invention can be formed by arranging and bonding a plurality of targets 20 to a Cu base material 10 . A gap 30 of 0.1 mm to 1.0 mm is formed between the targets.

As shown in FIG. 2 , on the surface of the substrate 10 , the substrate protection member 50 is attached at a position corresponding to the gap formed between the targets. The base material protection member can be attached to the surface of the base material 10 using a bonding material or conductive double-sided tape.

A plurality of target members are arranged as shown in FIG. 1 , and are joined using a joining material of In or Sn. The bonding is performed by coating the molten bonding material on the surface of the base material, arranging the target material on the bonding material, and then cooling to room temperature.

FIG. 3 shows a schematic cross-sectional view of a case where a single-layer substrate protective member is used. The single-layer base material protection member 50 has a thickness of 0.0001 mm to 1.0 mm. The base material protection member is made of any one of Zn, Ta, and Nb, or contains any two or more of In, Zn, Ta, and Nb. Alloy, or ceramic containing any one or more of In, Zn, Ta, and Nb. The In bonding material 60 is present on both end sides of the single-layer base material protective member 50 .

In FIG. 4 , a schematic cross-sectional view of a double-layered base material protective member obtained by laminating base material protective members of the same width is shown. The base material protective member 50 with a double-layer structure includes a first base material protective member 51 and a second base material protective member 52 . Furthermore, in consideration of workability and the like, the widths of the first base material protective member 51 and the second base material protective member are preferably 5 mm to 20 mm. Furthermore, the bonding material 60 made of In is present on both end sides of the first base material protective member 51 and the second base material protective member 52 . Furthermore, although a two-layer structure is shown in FIG. 4 , the substrate protection member may also adopt a three-layer or more structure. For example, considering the difference in linear expansion coefficient between the material of the first base material protective member and the material of the second base material protective member, an intermediate material of the first base material protective member and the second base material protective member may be used. The linear expansion rate of the material is used to set the middle layer.

In FIG. 5 , a schematic cross-sectional view of a double-layered base material protective member obtained by laminating base material protective members of different widths is shown. The base material protective member 50 with a double-layer structure includes a first base material protective member 51 and a second base material protective member 52 . Furthermore, in consideration of workability, etc., the width of the first base material protective member 51 is 5 mm to 20 mm, the width of the second base material protective member 52 is 8 mm to 30 mm, and the width of the second base material protective member 52 is relatively small. The first base material protective member is wide. Furthermore, by arranging the first base material protective member 51 substantially in the center of the second base material protective member, the second base material protective member 52 is exposed on both end sides of the first base material protective member. The width of the exposed portion is 1.5 mm to 5 mm on each of the two end sides. Furthermore, the bonding material 60 made of In is present on both end sides of the first base material protective member 51 and the second base material protective member 52 . Furthermore, although a two-layer structure is shown in FIG. 5 , the substrate protection member may also adopt a three-layer or more structure. For example, considering the difference in linear expansion coefficient between the material of the first base material protective member and the material of the second base material protective member, an intermediate material of the first base material protective member and the second base material protective member may be used. The linear expansion rate of the material is used to set the middle layer.

The second base material protective member 52 shown in Figures 4 and 5 has a thickness of 0.1 mm to 0.7 mm, and includes Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ag, and Any metal among them, or an alloy containing any of them. The first base material protective member 51 shown in Figures 4 and 5 has a thickness of 0.0001 mm to 0.3 mm, and is made of any one of Zn, Ta, and Nb, or any two of In, Zn, Ta, and Nb. It is formed from the above alloys or ceramics containing any one or more of In, Zn, Ta, and Nb.

The double-layer structure substrate protective member shown in Figures 4 and 5 can be produced, for example, as follows: by plasma spraying, the powder of Ta ₂ O ₅ or Nb ₂ O ₅ is blown onto 0.3 mm thick Cu Sheet metal.

In FIG. 6 , a schematic cross-sectional view is shown of a variation using a single-layer substrate protective member. In FIG. 6 , a single layer of substrate protection member 50 is filled in the gap 30 between the targets 20 . In this case, the thickness of the substrate protective member 50 is set to 0.0001 mm to 1.0 mm so that the target 20 and the substrate protective member 50 are not on the same plane. Thereby, sputtering of the base material protective member 50 can be suppressed. Furthermore, in this variation, the bonding material 60 of In exists between the target 20 and the base material protective member 50 and the base material 10 .

In FIG. 7 , an example of the TFT element 100 is schematically shown. The TFT element 100 shown in this figure is formed on one side of the glass substrate 110. A gate electrode 120 is disposed on one surface of the glass substrate 110, and a gate insulating film 130 is formed to cover it. On the gate insulating film 130, the source electrode 160, the drain electrode 161 and the channel layer 140 are arranged. An etching stop layer 150 is disposed on the channel layer 140 . Furthermore, a protective layer 170 is arranged on the uppermost part. In the TFT device 100 having this structure, for example, the target material of the present invention can be used to form the channel layer 140 . In this case, the channel layer 140 contains an oxide including indium (In) element, zinc (Zn) element and added element (X), and atoms of indium (In) element, zinc (Zn) element and added element (X) The ratio satisfies the above equation (1). Furthermore, the above formulas (2) and (3) are satisfied.

In terms of performance improvement of the device, it is preferable that the oxide semiconductor device formed from the target material of the present invention has an amorphous structure.

In addition, in view of the above-mentioned embodiment, the present invention also includes the following inventions. [1] A sputtering target formed by joining a plurality of sputtering targets to a base material using a joining material, and the plurality of sputtering targets contain an element including indium (In), zinc (Zn), and An oxide of added element (X), the added element (X) includes at least one element selected from tantalum (Ta) and niobium (Nb), and the atomic ratio of each element satisfies formulas (1) to (3) ( In the formula, 0.015 (3) This sputtering target has a base material protective member arranged in a gap formed between the plurality of sputtering targets. [2] The sputtering target according to [1], wherein the substrate protective member contains any one of Zn, Ta, and Nb, or contains any two or more of In, Zn, Ta, and Nb. alloy. [3] The sputtering target according to [1], wherein the substrate protective member contains ceramic containing at least one of In, Zn, Ta, and Nb. [4] The sputtering target according to [3], wherein the ceramic contains an oxide, nitride, or oxynitride containing at least one of In, Zn, Ta, and Nb. [5] The sputtering target according to [3] or [4], wherein the ceramic contains an oxide containing at least one of In, Zn, Ta, and Nb. [6] The sputtering target according to any one of [1] to [5], wherein the base material protective member has a first base material protective member on the sputtering target side and a second base member on the base material side. A structure obtained by laminating material protective components. [7] The sputtering target according to [6], wherein the second base material protective member contains Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ag, and Ta. Any metal, or an alloy containing any two or more of these metals, and the above-mentioned first substrate protective member contains any metal of Zn, Ta, and Nb, or contains In, Zn, Ta, and Nb Any two or more alloys. [8] The sputtering target according to [6], wherein the second base material protective member contains Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ag, and Ta. Any metal, or an alloy containing any two or more of these metals, and the first substrate protective member contains ceramic containing any one or more of In, Zn, Ta, and Nb. [9] The sputtering target according to [8], wherein the first substrate protective member contains an oxide, a nitride, or an oxynitride containing at least one of In, Zn, Ta, and Nb. [10] The sputtering target according to [8] or [9], wherein the first substrate protective member contains an oxide containing at least one of In, Zn, Ta, and Nb. [11] The sputtering target according to any one of [1] to [10], wherein the added element (X) is tantalum (Ta). [12] The sputtering target according to any one of [1] to [11], wherein the sputtering target material contains an In ₂ O ₃ phase and a Zn ₃ In ₂ O ₆ phase. [13] The sputtering target according to [12], wherein the size of the crystal grains of the In ₂ O ₃ phase is 0.1 μm or more and 3.0 μm or less, and the size of the crystal grains of the Zn ₃ In ₂ O ₆ phase is 0.1 μm or more. 3.9 μm or less. [14] The sputtering target according to any one of [1] to [13], which further satisfies Formula (4). 0.970≦In/(In＋X)≦0.999 (4) Example

Hereinafter, the present invention will be described in more detail through examples. However, the scope of the present invention is not limited to this embodiment.

[Example 1 (Examples 1-1 to 1-6)] Using zirconia balls, In ₂ O ₃ powder with an average particle diameter D ₅₀ of 0.6 μm and ZnO powder with an average particle diameter D ₅₀ of 0.8 μm were used. and Ta ₂ O ₅ powder with an average particle size D ₅₀ of 0.6 μm were dry-mixed in a ball mill to prepare mixed raw material powder. The average particle diameter D ₅₀ of each powder was measured using a particle size distribution measuring device MT3300EXII manufactured by MicrotracBEL Co., Ltd. During the measurement, water was used as the solvent and the refractive index of the measured substance was 2.20. The mixing ratio of each powder was set so that the atomic ratio of In, Zn, and Ta would be the value shown in Table 4 below.

To the tank in which the mixed raw material powder is prepared, 0.2 mass% of the binder relative to the mixed raw material powder, 0.6 mass% of the dispersant relative to the mixed raw material powder, and 20 mass% of water relative to the mixed raw material powder are added. The slurry is prepared by mixing in a ball mill with zirconia balls.

The prepared slurry is flowed into a metal mold sandwiching a filter, and then the water in the slurry is discharged to obtain a formed body. This molded body is fired to produce a sintered body. The calcination was performed in an environment with an oxygen concentration of 20% by volume, with a calcination temperature of 1400°C, a calcination time of 8 hours, a heating rate of 50°C/hour, and a cooling rate of 50°C/hour. During the calcination, 1100°C was maintained for 6 hours to promote the formation of Zn ₅ In ₂ O ₈ .

The sintered body obtained in this way was cut to obtain an oxide sintered body (target material) with a width of 210 mm, a length of 710 mm, and a thickness of 6 mm. Use #170 grinding stone during cutting.

Cut a φ8 inch target from the target and divide it into 2 parts in the center. Using In solder, the target divided into two parts was joined to a Cu backing plate (base material) so that the gap formed between the targets became 0.5 mm, thereby obtaining a sputtering target. At this time, a substrate protective member is placed between the Cu backing plate and the target along the gap formed between the targets.

[Example 1-1] In the above-mentioned sputtering target, a Ta metal sheet with a thickness of 0.3 mm and a width of 20 mm was arranged as a single-layer substrate protection member. [Example 1-2] A Zn metal sheet with a thickness of 0.3 mm and a width of 20 mm was arranged as a single-layer substrate protection member. [Example 1-3] A ceramic sheet with a thickness of 0.3 mm and a width of 20 mm and the same composition as the target material was arranged as a single-layer substrate protection member. [Example 1-4] By sputtering, a Ta film with a thickness of 0.0001 mm and a width of 20 mm was formed on the second base material protective member of a Cu metal sheet with a thickness of 0.3 mm and a width of 20 mm as the first base material protection member. The member is configured as a base material protective member of a laminated structure. [Example 1-5] By plasma spraying, a Ta ₂ O ₅ film with a thickness of 0.1 mm and a width of 20 mm was formed on the second base material protective member of a Cu metal sheet with a thickness of 0.3 mm and a width of 20 mm. The first base material protective member arranges the obtained member as a base material protective member of a laminated structure. [Example 1-6] Using plasma spraying, a Cu metal sheet with a thickness of 0.3 mm and a width of 20 mm was formed on the second base material protective member of a Cu metal sheet with a thickness of 0.1 mm and a width of 20 mm and the same composition as the target material. The film serves as the first base material protective member, and the obtained member is arranged as a base material protective member of a laminated structure. [Comparative Example 1] Joining was performed without arranging the base material protective member in the gap portion.

[Examples 2 to 7] Each raw material powder was mixed so that the atomic ratio of In, Zn, and Ta in Example 1 would become the value shown in Table 4 below. Except for this, a sputtering target was obtained in the same manner as in Example 1. In addition, the same members as those in Examples 1-5 were arranged as base material protective members.

[Examples 8-1 to 8-6] In Example 1, Nb ₂ O 5 powder _having an average particle diameter D ₅₀ of 0.7 μm was used instead of the Ta ₂ O ₅ powder. Each raw material powder was mixed so that the atomic ratio of In, Zn, and Nb would become the value shown in Table 1 below. Except for this, a sputtering target was obtained in the same manner as in Example 1.

[Example 8-1] In the above-mentioned sputtering target, an Nb metal sheet with a thickness of 0.3 mm and a width of 20 mm was arranged as a single-layer substrate protection member. [Example 8-2] A Zn metal sheet with a thickness of 0.3 mm and a width of 20 mm was arranged as a single-layer substrate protection member. [Example 8-3] A ceramic sheet with a thickness of 0.3 mm and a width of 20 mm and the same composition as the target material was arranged as a single-layer substrate protection member. [Example 8-4] By sputtering, an Nb film with a thickness of 0.0001 mm and a width of 20 mm was formed on the second base material protection member of a Cu metal sheet with a thickness of 0.3 mm and a width of 20 mm as the first base material protection member. The member is configured as a base material protective member of a laminated structure. [Example 8-5] By plasma spraying, an Nb ₂ O ₅ film with a thickness of 0.1 mm and a width of 20 mm was formed on the second base material protective member of a Cu metal sheet with a thickness of 0.3 mm and a width of 20 mm. The first base material protective member arranges the obtained member as a base material protective member of a laminated structure. [Example 8-6] By plasma spraying, a Cu metal sheet with a thickness of 0.3 mm and a width of 20 mm was formed on the second base material protective member of a Cu metal sheet with a thickness of 0.1 mm and a width of 20 mm and the same composition as the target material. The film serves as the first base material protective member, and the obtained member is arranged as a base material protective member of a laminated structure. [Comparative Example 2] Joining was performed without arranging the base material protective member in the gap portion.

[Example 9 (Examples 9-1 to 9-9)] In Example 1, the atomic ratio of Ta ₂ O ₅ powder and Nb ₂ O ₅ powder to In, Zn, Ta and Nb was as shown in Table 2 below. Mix as shown instead of Ta ₂ O ₅ powder. The molar ratio of Ta and Nb is set to Ta:Nb=3:2. Except for this, a sputtering target was obtained in the same manner as in Example 1.

[Example 9-1] In the above-mentioned sputtering target, a Ta metal sheet with a thickness of 0.3 mm and a width of 20 mm was arranged as a single-layer substrate protection member. [Example 9-2] An Nb metal sheet with a thickness of 0.3 mm and a width of 20 mm was arranged as a single-layer substrate protection member. [Example 9-3] A Zn metal sheet with a thickness of 0.3 mm and a width of 20 mm was arranged as a single-layer substrate protection member. [Example 9-4] A ceramic sheet with a thickness of 0.3 mm and a width of 20 mm and the same composition as the target material was arranged as a single-layer substrate protection member. [Example 9-5] By sputtering, a Ta film with a thickness of 0.0001 mm and a width of 20 mm was formed on the second base material protective member of a Cu metal sheet with a thickness of 0.3 mm and a width of 20 mm as the first base material protection member. The member is configured as a base material protective member of a laminated structure. [Example 9-6] By sputtering, an Nb film with a thickness of 0.0001 mm and a width of 20 mm was formed on the second base material protection member of a Cu metal sheet with a thickness of 0.3 mm and a width of 20 mm as the first base material protection member. The member is configured as a base material protective member of a laminated structure. [Example 9-7] A Ta 2 O ₅ film with a thickness _of 0.1 mm and a width of 20 mm was formed on the second base material protective member of a Cu metal sheet with a thickness of 0.3 mm and a width of 20 mm by plasma spraying. The first base material protective member arranges the obtained member as a base material protective member of a laminated structure. [Example 9-8] By plasma spraying, an Nb ₂ O ₅ film with a thickness of 0.1 mm and a width of 20 mm was formed on the second base material protective member of a Cu metal sheet with a thickness of 0.3 mm and a width of 20 mm. The first base material protective member arranges the obtained member as a base material protective member of a laminated structure. [Example 9-9] By plasma spraying, a Cu metal sheet with a thickness of 0.3 mm and a width of 20 mm was formed on the second base material protective member of a Cu metal sheet with a thickness of 0.1 mm and a width of 20 mm and the same composition as the target material. The film serves as the first base material protective member, and the obtained member is arranged as a base material protective member of a laminated structure. [Comparative Example 3] Joining was performed without arranging the base material protective member in the gap portion.

The ratio of each metal contained in the target materials obtained in the Examples and Comparative Examples was measured by ICP emission spectroscopy. It was confirmed that the atomic ratios of In, Zn, Ta, and Nb were the same as the raw material ratios shown in Table 4.

[Evaluation 1] The relative density of the target material obtained in the Example was measured by the following method. The targets obtained in Examples 1 to 9 were subjected to XRD measurement under the following conditions to confirm the presence or absence of the In ₂ O ₃ phase and the Zn ₃ In ₂ O ₆ phase. In addition, SEM observation was performed on the target materials obtained in Examples 1 to 9, and the size of the crystal grains of the In ₂ O ₃ phase and the size of the crystal grains of the Zn ₃ In ₂ O ₆ phase were measured by the following method. The results are shown in Table 4 below.

[Relative Density] Divide the mass of the target in air by the volume (mass of target in water/specific gravity of water at measurement temperature), and compare it to the theoretical density ρ (g/cm ³ ) based on the following formula (i) The percentage value is set as relative density (unit: %). [Number 1] (In the formula, C _i represents the content (mass %) of the constituent materials of the target, and ρ _i represents the density of each constituent material corresponding to C _i (g/cm ³ )) In the case of the present invention, the composition of the target material The substance is calculated as In ₂ O ₃ , ZnO, Ta ₂ O ₅ , Nb ₂ O _5. For example, C ₁ : mass % of In ₂ O ₃ of the target material ρ ₁ : density of In ₂ O ₃ (7.18 g/cm ³ ) C ₂ : Mass % of ZnO in the target ρ ₂ : Density of ZnO (5.60 g/cm ³ ) C ₃ : Mass % of Ta ₂ O ₅ in the target ρ ₃ : Density of Ta ₂ O ₅ (8.73 g/ cm ³ ) C ₄ : Mass % of Nb ₂ O ₅ in the target material ρ ₄ : Density of Nb ₂ O ₅ (4.60 g/cm ³ ) Applying to formula (i), the theoretical density ρ can be calculated. The mass % of In ₂ O ₃ , the mass % of ZnO, the mass % of Ta ₂ O ₅ , and the mass % of Nb ₂ O ₅ can be determined based on the analysis results of each element of the target material obtained by ICP emission spectrometry.

[XRD measurement conditions] Use SmartLab (registered trademark) of Rigaku Co., Ltd. The measurement conditions are as follows. The results of the XRD measurement of the target material obtained in Example 1 are shown in FIG. 8 . ・Line source: CuKα ray ・Tube voltage: 40 kV ・Tube current: 30 mA ・Scan speed: 5 deg/min ・Step: 0.02 deg ・Scanning range: 2θ=5 degrees to 80 degrees

[The size of the crystal grains of the In ₂ O ₃ phase and the size of the crystal grains of the Zn ₃ In ₂ O ₆ phase] Using a scanning electron microscope SU3500 manufactured by Hitachi High-Technologies, the surface of the target material was observed by SEM and crystallization was carried out. Evaluation of composition phase or crystal shape. Specifically, the cut surface obtained by cutting the target material was ground in stages using emery paper #180, #400, #800, #1000, and #2000, and finally polished and polished to a mirror surface. SEM observation was performed on the mirror-finished surface. In the evaluation of the crystal shape, 10 visual fields of BSE-COMP (Backscattered Electron-Compositional) images in the range of 87.5 μm × 125 μm were randomly taken at a magnification of 1000 times to obtain SEM images.

Using image processing software: ImageJ 1.51k (http://imageJ.nih.gov/ij/, source: National Institutes of Health (NIH: National Institutes of Health)), the obtained SEM images were processed parse. The specific procedures are as follows. The sample used for taking SEM images was thermally etched at 1100°C for 1 hour and observed by SEM to obtain an image showing grain boundaries. The obtained image was first traced along the grain boundaries of the In ₂ O ₃ phase. After all drawings are completed, perform particle analysis (Analyze→Analyze Particles) to obtain the area of each particle. Thereafter, the equal-area circle diameter is calculated based on the obtained area of each particle. The arithmetic mean of the equal-area circle diameters of all particles calculated in 10 fields of view is set as the size of the crystal grains of the In ₂ O ₃ phase. Next, the grain boundaries of the Zn ₃ In ₂ O ₆ phase were drawn and analyzed in the same manner to obtain the area of each particle. The diameter of an equal-area circle was calculated based on the obtained area of each particle. The arithmetic mean of the equal-area circle diameters of all particles calculated in 10 fields of view is set as the size of the crystal grains of the Zn ₃ In ₂ O ₆ phase.

[Evaluation 2] For the sputtering targets of Examples 1-1 to 1-6, Examples 8-1 to 8-6, Examples 9-1 to 9-6 and Comparative Examples 1 to 3, the backing plate (base material) was made of Cu. ) to evaluate the amount of Cu mixed into the sputtered film. Specifically, a sputtering device (SML-464 manufactured by Tokki Co., Ltd.) was used to form a thin film with a thickness of 14 μm on a glass substrate (OA-10 manufactured by Nippon Electric Glass Co., Ltd.). Then, a portion corresponding to the portion directly above the gap formed between the targets is cut out of the film-formed base material. The Cu content in each film was measured and evaluated by the ICP-OES (Optical Emission Spectrometry) method on the cut substrate using an ICP emission spectrometry analyzer 720 ICP-OES manufactured by Agilent Technologies. The results are shown in Tables 1 to 3.

[Table 1] Protective components Cu content of film (ppm) Example 1-1 Ta piece (single layer) <2 Example 1-2 Zn sheet (single layer) <2 Example 1-3 Target homogeneous sheet (single layer) <2 Examples 1-4 Ta/Cu (laminate) <2 Examples 1-5 Ta ₂ O ₅ spray/Cu (layered) <2 Examples 1-6 The same target composition is spraying/Cu (lamination) <2 Comparative example 1 No protective components twenty one

[Table 2] Protective components Cu content of film (ppm) Example 8-1 Nb sheet (single layer) <2 Example 8-2 Zn sheet (single layer) <2 Example 8-3 Target homogeneous sheet (single layer) <2 Example 8-4 Nb/Cu(Laminated) <2 Example 8-5 Nb ₂ O ₅ spray/Cu (layered) <2 Example 8-6 The same target composition is spraying/Cu (lamination) <2 Comparative example 2 No protective components twenty three

[table 3] Protective components Cu content of film (ppm) Example 9-1 Ta piece (single layer) <2 Example 9-2 Nb sheet (single layer) <2 Example 9-3 Zn sheet (single layer) <2 Example 9-4 Target homogeneous sheet (single layer) <2 Example 9-5 Ta/Cu (laminate) <2 Example 9-6 Nb/Cu(Laminated) <2 Example 9-7 Ta ₂ O ₅ spray/Cu (layered) <2 Example 9-8 Nb ₂ O ₅ spray/Cu (layered) <2 Example 9-9 The same target composition is spraying/Cu (lamination) <2 Comparative example 3 No protective components twenty one

As shown in Tables 1 to 3, when a substrate protective member is provided, the Cu content of the sputtered film does not reach 2 ppm. On the other hand, when no substrate protective member is provided, the Cu content of the sputtered film is 21 to 23 ppm. From this result, it can be seen that by arranging the base material protective member, Cu can be prevented from being mixed into the sputtered film.

[Evaluation 3] Using the sputtering targets of Examples 1-5, Examples 2 to 7, Example 8-5, Example 9-6, and Comparative Examples 1 to 3, the sputtering targets shown in Figure 6 were produced by photolithography. TFT component 1. In the production of the TFT element 1, a DC (Direct Current, DC) sputtering device is first used to form a Mо thin film on a glass substrate (OA-10 manufactured by Nippon Electric Glass Co., Ltd.) 10 as the gate electrode 20. Then, under the following conditions, a SiO _x thin film is formed as the gate insulating film 30 . Film forming device: Plasma CVD (Chemical Vapor Deposition, chemical vapor deposition) device PD-2202L manufactured by Samco Co., Ltd. Film forming gas: SiH ₄ /N ₂ O/N ₂ mixed gas Film forming pressure: 110 Pa Substrate Temperature: 250～400℃

Then, using the sputtering targets obtained in Examples 1-5, Examples 2 to 7, Example 8-5, Example 9-6, and Comparative Examples 1 to 3, the channel layer 40 was subjected to the following conditions: Sputtering is used to form a film with a film thickness of 30 nm. Furthermore, when the channel layer 40 is formed, the film formation is performed directly above the gap formed between the targets.・Film forming device: DC sputtering device SML-464 manufactured by Tokki Co., Ltd. ・Ultimate vacuum degree: less than 1×10 ^-4 Pa ・Sputtering gas: Ar/O ₂ mixed gas ・Sputtering gas pressure: 0.4 Pa ・O ₂ gas partial pressure: 50% ・Substrate temperature: room temperature ・Sputtering power: 3 W/cm ²

Furthermore, a SiO _x thin film was formed as the etching stopper layer 50 using the above plasma CVD apparatus. Next, the above-mentioned DC sputtering apparatus was used to form a Mo thin film as the source electrode 60 and the drain electrode 61 . A SiO _x thin film was formed as the protective layer 70 using the above plasma CVD apparatus. Finally, heat treatment is performed at 350°C. The TFT element 1 obtained in this manner was measured for its transmission characteristics at a drain voltage Vd = 5 V. The measured transmission characteristics are field-effect mobility μ (cm ² /Vs), SS (Subthreshold Swing, sub-critical swing) value (V/dec) and threshold voltage Vth (V). The transmission characteristics were measured using a semiconductor device analyzer B1500A manufactured by Agilent Technologies Co., Ltd. The measurement results are shown in Table 1 and Table 2. Furthermore, although not shown in the table, the inventors confirmed through XRD measurement that the channel layer 40 of the TFT element 1 obtained in each example has an amorphous structure.

The field-effect mobility is calculated based on the change of the drain current relative to the gate voltage when the drain voltage is constant in the saturation region of MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) operation. The channel mobility of , the larger the value, the better the transmission characteristics. The SS value is the gate voltage required to increase the drain current by one digit near the critical voltage. The smaller the value, the better the transfer characteristics. The critical voltage is the voltage at which the drain current flows and becomes 1 nA when a positive voltage is applied to the drain electrode and a positive or negative voltage is applied to the gate electrode. The value is preferably close to 0 V. Specifically, it is more preferably -2 V or more, still more preferably -1 V or more, and still more preferably 0 V or more. Moreover, it is more preferably 3 V or less, still more preferably 2 V or less, still more preferably 1 V or less.

[Table 4] Example 1 (Examples 1-5) Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 (Example 8-5) Example 9 (Example 9-6) Comparative example 1 Comparative example 2 Comparative example 3 (In＋X)/(In＋Zn＋X) 0.700 0.700 0.700 0.600 0.500 0.740 0.400 0.700 0.700 0.700 0.700 0.700 Zn/(In＋Zn＋X) 0.300 0.300 0.300 0.400 0.500 0.260 0.600 0.300 0.300 0.300 0.300 0.300 X/(In＋Zn＋X) 0.005 0.001 0.010 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 In/(In＋X) 0.993 0.999 0.986 0.992 0.990 0.993 0.988 0.993 0.993 0.993 0.993 0.993 Add element(X) Ta Ta Ta Ta Ta Ta Ta Nb Ta,Nb Ta Nb Ta,Nb Relative density[%] 98.2 98.5 98.7 98.4 98.5 98.7 98.9 98.6 98.8 98.2 98.6 98.8 Grain size [μm] In ₂ O ₃ phase 2.2 2.0 2.3 1.8 1.7 2.2 1.7 2.1 2.2 2.2 2.1 2.2 Zn ₃ In ₂ O ₆ phase 2.1 2.0 2.2 2.5 3.4 2.0 10.7 2.0 2.1 2.1 2.0 2.1 Transmission characteristics Field effect mobility μ[cm ² /Vs] 72.5 100.9 77.1 79 69.8 67.8 66.1 76.5 77.3 14.8 14.2 10.9 Threshold voltage Vth[V] 0.3 0.0 0.0 1.1 2.3 0.0 4.8 0.6 0.2 -17.3 -16.9 -16.6 SS value[V/dec] 0.25 0.27 0.26 0.28 0.25 0.25 0.24 0.3 0.25 0.60 0.55 0.57

From the results shown in Table 4, it can be seen that the TFT element manufactured using the target material obtained in each example has excellent transmission characteristics.

Furthermore, the target material obtained in Example 1 contained the In ₂ O ₃ phase and the Zn ₃ In ₂ O ₆ phase. The same results were also obtained for the targets obtained in Examples 2 to 9. [Industrial availability]

According to the present invention, it is possible to provide a sputtering target that is a large-area sputtering target obtained by joining a plurality of target materials, but can effectively prevent the constituent materials of the base material from being mixed into the thin film to be formed. The sputtering target of the present invention can be suitably used in the technical field of thin film transistors (TFT) used in flat panel displays (FPD). In addition, by arranging the base material protective member in the gap formed between the plurality of sputtering targets, the constituent materials of the base material are not sputtered compared to the previous sputtering target, and the constituent materials can be effectively prevented from being mixed in. to the film forming film. Therefore, the production of untargeted sputtered films containing many impurities can be suppressed, so sustainable management, effective utilization, and decarbonization (carbon neutrality) of natural resources can be achieved.

10:Substrate 20:Target 30: gap 50:Substrate protection component 51: First base material protective member 52: Second base material protective member 60:joining material 100:TFT component 110:Glass substrate 120: Gate electrode 130: Gate insulation film 140: Channel layer 150: Etch stop layer 160: Source electrode 161: Drain electrode 170:Protective layer

FIG. 1 is a schematic diagram showing a schematic cross-sectional view of one embodiment of the sputtering target of the present invention. FIG. 2 is a schematic diagram showing a schematic cross-sectional view of another embodiment of the sputtering target of the present invention. FIG. 3 is a schematic diagram showing a schematic cross-sectional view of another embodiment of the sputtering target of the present invention. FIG. 4 is a schematic diagram showing a schematic cross-sectional view of another embodiment of the sputtering target of the present invention. FIG. 5 is a schematic diagram showing a schematic cross-sectional view of another embodiment of the sputtering target of the present invention. FIG. 6 is a schematic diagram showing a schematic cross-sectional view of another embodiment of the sputtering target of the present invention. 7 is a schematic diagram showing the structure of an embodiment of a TFT element produced using the sputtering target of the present invention. FIG. 8 is a graph showing the XRD measurement results of the target material obtained in Example 1.

10:Substrate

20:Target

30: gap

Claims (14)

A sputtering target formed by joining a plurality of sputtering targets to a base material using a joining material. The plurality of sputtering targets contain an element including indium (In), zinc (Zn) and an additive element ( Oxides of X), The additional element (X) includes at least one element selected from tantalum (Ta) and niobium (Nb), The atomic ratio of each element satisfies formulas (1) to (3) at the same time (X in the formula is set to the sum of the content ratios of the above-mentioned added elements), 0.4≦(In+X)/(In+Zn+X)<0.75 (1) 0.25＜Zn/(In＋Zn＋X)≦0.6     (2) 0.001≦X/(In＋Zn+X)≦0.015    (3) This sputtering target has a base material protective member arranged in a gap formed between the plurality of sputtering targets. The sputtering target of Claim 1, wherein the base material protective member contains any one of Zn, Ta, and Nb, or an alloy containing any two or more of In, Zn, Ta, and Nb. The sputtering target of Claim 1, wherein the substrate protective member includes ceramics containing at least one of In, Zn, Ta, and Nb. The sputtering target of claim 3, wherein the ceramic includes an oxide, nitride, or oxynitride containing any one or more of In, Zn, Ta, and Nb. The sputtering target of claim 3 or 4, wherein the ceramic includes an oxide containing at least one of In, Zn, Ta, and Nb. The sputtering target according to any one of claims 1 to 4, wherein the base material protective member has a structure in which a first base material protective member on the sputtering target side and a second base material protective member on the base material side are laminated. . The sputtering target of claim 6, wherein the second base material protective member includes any one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ag, and Ta, Or an alloy containing any two or more of these metals, and the above-mentioned first base material protective member contains any one of Zn, Ta, and Nb, or contains any two of In, Zn, Ta, and Nb Alloys above. The sputtering target of claim 6, wherein the second base material protective member includes any one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ag, and Ta, Or an alloy containing any two or more of these metals, and the first base material protective member contains a ceramic containing at least one of In, Zn, Ta, and Nb. The sputtering target of claim 8, wherein the first base material protective member includes an oxide, nitride, or oxynitride containing at least one of In, Zn, Ta, and Nb. The sputtering target of Claim 8 or 9, wherein the first base material protective member contains an oxide containing at least one of In, Zn, Ta, and Nb. The sputtering target of any one of claims 1 to 4, wherein the added element (X) is tantalum (Ta). The sputtering target as claimed in any one of claims 1 to 4, wherein the sputtering target material includes an In ₂ O ₃ phase and a Zn ₃ In ₂ O ₆ phase. Such as the sputtering target of claim 12, wherein the size of the crystal grains of the In ₂ O ₃ phase is 0.1 μm or more and 3.0 μm or less, and the size of the crystal grains of the Zn ₃ In ₂ O ₆ phase is 0.1 μm or more and 3.9 μm or less. As claimed in any one of items 1 to 4, the sputtering target further satisfies formula (4), 0.970≦In/(In＋X)≦0.999 (4).