WO2016072441A1

WO2016072441A1 - Ito sputtering target and method for manufacturing same, ito transparent electroconductive film, and method for manufacturing ito transparent electroconductive film

Info

Publication number: WO2016072441A1
Application number: PCT/JP2015/081123
Authority: WO
Inventors: 崇掛野
Original assignee: Ｊｘ金属株式会社
Priority date: 2014-11-07
Filing date: 2015-11-05
Publication date: 2016-05-12
Also published as: TWI594970B; CN106460161B; KR20180093140A; CN106460161A; KR20160148593A; JP6291593B2; KR102030892B1; JPWO2016072441A1; TW201630849A

Abstract

The present invention relates to a sputtering target characterized by being a sintered compact comprising In, Sn, O, and unavoidable impurities, the sintered compact containing Sn in an atomic ratio Sn/(In + Sn) of 1.8% to 3.7% (excluding 3.7%), the average crystal grain size of the sintered compact being in the range of 1.0-5.0 µm, vacancies having a major-axis diameter of 0.1-1.0 µm constituting an area ratio of 0.5% or less, the sintered compact having two phases including an indium oxide phase and a tin-oxide-rich phase, the area ratio of the tin-oxide-rich phase being 0.1-1.0%, and 95% or more of the tin-oxide-rich phase being present at grain boundary triple points. The present invention makes it possible to provide an ITO sputtering target suitable for forming a transparent electroconductive film and which has a low tin oxide content and enables a low-resistance film to be obtained even at low temperature, the sputtering target having a small grain size, high density, and high strength, and making it possible to reduce the occurrence of arcing or nodules.

Description

ITO sputtering target, method for producing the same, ITO transparent conductive film, and method for producing ITO transparent conductive film

The present invention relates to an ITO sputtering target suitable for forming an ITO film. In particular, the present invention relates to an ITO sputtering target that has a small target particle size, high density, high strength, and reduced arcing and nodules, a manufacturing method thereof, an ITO transparent conductive film, and an ITO transparent conductive film manufacturing method. Examples of main applications of the present invention include touch panels, flat panel displays, organic EL, and solar cells.

In general, an ITO (indium-tin composite oxide) film is widely used as a transparent electrode (conductive film) in a display device centering on a liquid crystal display. As a method for forming the ITO film, a method generally called physical vapor deposition such as vacuum vapor deposition or sputtering is used. In particular, the magnetron sputtering method is often used because of operability and coating stability.

A film is formed by sputtering, in which a cation such as Ar ions is physically collided with a target placed on a cathode, and the material constituting the target is released by the collision energy, so that a substrate on the anode side facing the target is released. This is done by stacking films having the same composition as the target material. The coating method by sputtering has a feature that it can be formed from a thin film of several nm to a thick film of several tens of μm at a stable film formation speed by adjusting processing time, supply power and the like. .

In recent years, there has been a demand for ITO films used for capacitance type, resistance type touch panels, etc., and 10 wt. In addition to the ITO sputtering target containing about 0.1% tin (Sn), tin oxide is added in an amount of 1.0 to 50.0 wt. Targets with a wide composition range of less than 10% are being developed. For example, in Patent Document 1, a mixed powder with indium oxide containing 20 to 50 wt% tin oxide is press-molded, and this molded body is heated in a pure oxygen atmosphere at a temperature of 1500 to 1650 ° C. and a pressure of 0.15 to 1 MPa. It is known to produce an ITO sputtering target by pressure sintering.

As a typical patent for an ITO sputtering target, there is Patent Document 1 shown below. This patent is “an ITO sputtering target manufactured by powder metallurgy from raw materials mainly composed of indium oxide and tin oxide, having a surface roughness Ra of 0.5 μm or less and a density D ( g / cm ³ ) and bulk resistance value ρ (mΩcm) satisfying the following two expressions at the same time: an ITO sputtering target, a) 6.20 ≦ D ≦ 7.23, b ”−0.0676D + 0.887 ≧ ρ ≧ −0.0761D + 0.666. It is a technology about 20 years ago.
This patent discloses an ITO that hardly generates abnormal discharge or nodule during sputtering and has a minimum amount of gas adsorption so that a high-quality ITO film can be stably obtained under good film forming operations. It can be said that this is an epoch-making invention at that time that a sintered target can be realized.

As a measure for increasing the ITO target density, for example, in Patent Document 2 below, the median diameter obtained from the particle size distribution is in the range of 0.40 (excluding 0.40) to 1.0 μm, and from the particle size distribution. An ITO target formed using a tin oxide powder having a 90% particle size in the range of 3.0 μm or less is described.
However, when an ITO target containing a larger amount of tin oxide than before is produced using such tin oxide powder, macropores and microcracks are generated inside the sintered body, and the sintered body is processed. Cracks and cracks may occur during storage after storage or after processing. And they may affect the shipment of the product as a target.

In addition, the following Patent Document 3 discloses an ITO sintered body in which fine particles composed of In ₄ Sn ₃ O ₁₂ are present in the In ₂ O ₃ matrix, which is the main crystal grain, as a technology related to ITO, A technique for providing an ITO sputtering target having a low bulk resistance, characterized in that the fine particles have a three-dimensional star shape in which needle-like protrusions are formed radially from the virtual center of the particle, is disclosed.

Patent Document 4 below is made of In, Sn, and O, has a sintered density of 7.08 g / cm 3 or more, a bulk resistivity of 80 μΩcm to 100 μΩcm, and O / (In + Sn + O) of 1.75% or less (weight ratio). ) And an ITO sintered body that is 30% or less of the integrated intensity of the X-ray diffraction peak of the (200) plane of the In ₄ Sn ₃ O ₁₂ phase, and this sintered body is formed of In, Sn, and O. When sintering a body, a technique for switching a sintering atmosphere from an oxidizing atmosphere to a non-oxidizing atmosphere when the sintering temperature becomes 1400 ° C. or higher is disclosed.

In order to obtain a low-resistance film with ITO (tin oxide: 10 wt.%) That is generally used, it is necessary to perform heat treatment at 150 ° C. or higher, but there are cases where heat cannot be applied even at 150 ° C. . For example, a transparent conductive film used in a touch panel or the like is a structural problem, and when a heat cannot be applied during film formation or after film formation, a low resistance tin oxide composition that can obtain a low resistance film even at a low temperature can be obtained. ITO is used.
The ITO target having a low tin oxide composition changes the probability of existence of a tin-rich phase depending on the sintering temperature. Therefore, unless the sintering temperature is controlled, it is difficult to increase the density and it becomes difficult to control the crystal grain size. Also, the density may vary from lot to lot. Further, the dispersibility of the tin-rich phase is deteriorated, and the problem that nodules and arcing are likely to occur easily occurs.

Patent Documents 5 to 10 below propose an ITO sputtering target having a low tin oxide composition.
In Patent Document 5, the tin oxide content is 1.5% to 3.5% by mass, the relative density is 98% or more, the crystal phase is a single phase, the average crystal grain size is 10 μm or less, and the sintered body. Is characterized by a bending strength of 70 MPa or more, but the sintering temperature is as high as 1500 ° C., and it takes one effort to produce a molded body by mixing the first granulated powder and the second granulated powder. , Productivity is not so good.

Patent Document 6 includes indium oxide, tin oxide, and inevitable impurities. The tin oxide content is 2.5% by mass or more and 5.2% by mass or less, and the average density is 7.1 g / cm ³ or more. In addition, the ITO sputtering target has an average crystal grain size of 3 μm or more and less than 10 μm, but the holding temperature is as high as 1500 to 1600 ° C., and the strength of the sintered body is not described.

Patent Document 7, a tin content of 3 to 12 wt%, solid solution amount of tin that is dissolved in the _In 2 _{O 3} phase is at least 2 wt%, _In 2 _{O 3} phase and In The average crystal grain size of the phase in which tin element is dissolved in the ₂ O ₃ phase is in the range of 2 to 10 μm, and the maximum pore diameter present in the sintered body is 3 μm or less, Indium oxide / tin oxide sintered body characterized in that the maximum agglomerated diameter is 5 μm or less, the sintering temperature is 1500 ° C. or higher, and the average particle size in Examples and Comparative Examples is as large as 7 μm or more, The sintered body density is also as low as 6.9 g / cm ^{3 at the} maximum. Further, the strength of the sintered body is not mentioned.

Patent Document 8 discloses a sintered body made of indium, tin, and oxygen. The amount of tin is 2 to 4 wt%, the relative density is 90% or more, and the tin oxide phase and the intermediate compound phase other than the indium oxide phase have an area. It has a single-phase structure with a rate of 5% or less and a specific resistance value of 1 × 10 −3 Ω · cm or less, but the sintering temperature is as high as 1500 to 1700 ° C., and the sintered body The specific resistance is also high.

Patent Document 9 discloses a sintered body having a large area of 300 mm × 300 mm or more and a thickness of 6 mm or more, which is substantially composed of indium oxide and tin oxide, and the content of tin oxide is 35% by weight or less. Then, the average density of 7.13 g / cm ³ sintered density is not less than that, the maximum density difference in the plane direction of the sintered body is not more than 0.03 g / cm ³ , and further 2 μm or less in the central part in the thickness direction. in ITO sintered body number hole is equal to or is 500 / mm ² or less, and held at 1450 ° C. or higher sintering temperature, but is characterized by sintering, sintering temperature 1450 ° C. or higher The sintering method is also finely defined, and it cannot be said that productivity is good.

Patent Document 10 includes a sintered body that is substantially composed of indium, tin, and oxygen, has a relative density of 99% or more and has a plate thickness portion of 10 mm or more, and satisfies the following formula (1). Characteristic ITO sputtering target. Expression (1): Relative density (%) of central portion in thickness direction of sintered body / density of entire sintered body (%) ≧ 0.995 The temperature is as high as 1600 ° C., and although not described, it is assumed that the crystal grain size is large.
In addition, none of the above documents is produced from the viewpoint of increasing the small particle size, increasing the density, and increasing the strength by changing the tin oxide-rich phase by low-temperature sintering.

Japanese Patent No. 2750483 JP 2009-29706 A JP 2009-40621 A JP 2000-233969 A Japanese Patent No. 52069883 JP 2012-126937 A JP 1998-147862 A Patent No. 3503759 Japanese Patent No. 3988411 Japanese Patent No. 4934926

The present invention relates to an ITO sputtering target having a low tin oxide composition capable of obtaining a low-resistance film even at a low temperature. The ITO has a small target particle size, high density, high strength, and reduced arcing and nodules. A sputtering target is provided. Thus, it is an object to improve the quality and reliability of film formation.

In order to solve the above-described problems, the present invention provides the following inventions.
1) A sintered body composed of In, Sn, O, and inevitable impurities, and Sn / (In + Sn) is 1.8% or more and 3.7% or less (except for 3.7%) by atomic ratio. ), The average crystal grain size of the sintered body is in the range of 1.0 to 5.0 μm, and pores having a major axis diameter of 0.1 to 1.0 μm are 0.5% or less in area ratio The indium oxide phase and the tin oxide rich phase are two phases. The area ratio of the tin oxide rich phase is 0.1 to 1.0% or less, and 95% or more of the tin oxide rich phase is three grain boundaries. Sputtering target characterized by existing in importance.

2) The sputtering target according to 1) above, which contains Sn having an atomic ratio of Sn / (In + Sn) of 2.3 to 3.2%.
3) The sintered body density is 7.03 g / cm ³ or more, and the bulk resistivity is 0.10 to 0.15 mΩ · cm, according to any one of the above 1) or 2) Sputtering target.
4) The sputtering target according to any one of 1) to 3) above, wherein the maximum size of the tin oxide-rich phase is 1 μm or less.
5) The sputtering target according to any one of 1) to 4) above, wherein the bending strength is 100 MPa or more.

6) A method for producing a sputtering target comprising In, Sn, O, and inevitable impurities, wherein Sn / (In + Sn) is 1.8% or more in terms of atomic ratio of SnO ₂ powder and In ₂ O ₃ powder. It is characterized in that the ratio is adjusted so as to be 7% (excluding 3.7%) and mixed, and sintering is performed while maintaining the maximum sintering temperature at 1450 ° C. or lower in an oxygen atmosphere. A method of manufacturing an ITO sputtering target.
7) The SnO ₂ powder and the In ₂ O ₃ powder are mixed and sintered by adjusting the ratio so that Sn / (In + Sn) is 2.3 to 3.2% by atomic ratio. The manufacturing method of the sputtering target as described in said 6).
8) The method for producing a sputtering target as described in 6) or 7) above, wherein in the cooling step after sintering, the sintering target is held at a temperature lower by 100 ° C. ± 20 ° C. than the sintering holding temperature.

9) A transparent conductive film composed of In, Sn, O, and inevitable impurities, and Sn / (In + Sn) is 1.8% or more and 3.7% or less (provided that 3.7% A transparent film characterized in that the film has a film characteristic in which the film has a resistivity of 3.0 mΩ · cm or less and a transmittance at a wavelength of 550 nm of 80% or more. Conductive film.

10) The transparent conductive film as described in 8) above, which contains Sn having an atomic ratio of Sn / (In + Sn) of 2.3 to 3.2%.
11) The transparent conductive film according to any one of 9) or 10) above, wherein the crystallization temperature is 120 ° C. or lower.

12) A method for producing a transparent conductive film by sputtering, wherein the substrate is kept unheated or kept at 150 ° C. or lower in a mixed gas atmosphere consisting of argon and oxygen and having an oxygen concentration of 4% or less. 5) A method for producing a transparent conductive film, wherein a film is formed on a substrate using the sputtering target according to any one of 5).

The present invention relates to an ITO sputtering target having a low tin oxide composition suitable for forming a transparent conductive film and capable of obtaining a low resistance film even at low temperatures. The target has a small particle size, high density, high strength, arcing and nodules. It is possible to provide a sputtering target capable of reducing. As a result, it is possible to improve the quality and reliability of film formation. As a result, there is an excellent effect that the productivity and reliability of the target can be improved.

An ITO sintered body containing Sn with an atomic ratio of Sn / (In + Sn) of 3.8%, Sn surface x2000 times by FE-EPMA (manufactured by JEOL Ltd., JXA-8500F type FE electron probe microanalyzer) It is a figure which shows an analysis result. It is a figure (A, B, C, D) explaining that a tin oxide rich phase exists 95% or more in a grain-boundary triple point. It is a figure (photograph) of a target after 35 hours continuous sputtering, and is a figure explaining a nodule coverage. It is a figure which shows the specific example (In the case of a round-shaped sintered compact, the case of a square-shaped sintered compact, the case of a cylindrical type) of the observation location of a sintered compact.

In the present invention, the sputtering target is a sintered body composed of In, Sn, O, and unavoidable impurities, and Sn / (In + Sn) is 1.8% or more and 3.7% or less (inclusive) (Except 3.7%), the average crystal grain size of the sintered body is in the range of 1.0 to 5.0 μm, and the pores with the major axis diameter of 0.1 to 1.0 μm are the area The ratio is 0.5% or less, and the indium oxide phase and the tin oxide rich phase are two phases. The area ratio of the tin oxide rich phase is 0.1 to 1.0% or less, and the tin oxide rich phase is 95%. % Or more is present at the grain boundary triple point.

The numerical limitation of 1.8%, which is Sn / (In + Sn) in terms of Sn and is the lower limit of 1.8% to 3.7% (excluding 3.7%), is 1.8% This is because the tin oxide-rich phase does not exist below. Further, the numerical limit of 3.7% (excluding 3.7%) which is the upper limit value is because the area ratio of the tin oxide rich phase is more than 1%. It is more effective to further contain Sn with an atomic ratio of Sn / (In + Sn) of 2.3 to 3.2%.
Further, the average crystal grain size of the sintered body needs to be in the range of 1.0 to 5.0 μm. When the average crystal grain size is less than 1.0 μm, there is a problem that the density does not increase because the crystal grain size is too small, and when it exceeds 5.0 μm, the bending strength of the sintered body is less than 100 MPa. Since it occurs, it is not preferable.

In the sintered body, the area ratio of pores having a major axis diameter of 0.1 to 1.0 μm is set to 0.5% or less because the presence of pores not only leads to a decrease in density but also the residual pores. Since it may cause arcing due to gas etc., it is better to use as little as possible. The holes having a major axis diameter of less than 0.1 μm in the sintered body can be ignored because they do not affect the characteristics of the target. On the other hand, pores exceeding 1.0 μm must be excluded.
The structure of the sintered body becomes two phases of an indium oxide phase and a tin oxide rich phase. In the area analysis by EPMA, the area ratio of the tin oxide-rich phase needs to be 0.1 to 1.0% or less. This is a necessary condition for realizing a sintered body having a small average crystal grain size and obtaining the characteristics of the sputtering target of the present invention.

The present invention requires that 95% or more of the tin oxide-rich phase is present at the grain boundary triple point. (The target is uniformly dispersed, and a tin oxide-rich phase is present as a dispersed state at the grain boundary triple point) In this case, the “grain boundary triple point” means that the particles in contact with each other are 3 This means that a tin oxide-rich phase is present in the almost central part of the individual assembly. As described later in detail, in order to achieve such a state (95% or more of the tin oxide rich phase is present at the grain boundary triple point), a low temperature of 100 ° C. ± 20 ° C. from the sintering holding temperature in the cooling step. It is necessary to hold in.
The ITO sputtering target can further increase the conductivity by setting the sintered body density to a high density of 7.03 g / cm ³ or more and the bulk resistivity to 0.10 to 0.15 mΩ · cm. The maximum size of the tin oxide-rich phase is desirably 1 μm, and a target that suppresses the coarsening of the tin oxide-rich phase is preferable.
In addition, it is desirable to increase the strength of the target by setting the bending strength of the sintered body of the ITO sputtering target to 100 MPa or more, and the present invention can realize this.

Indium oxide of the present invention, in the production of sintered bodies ITO sputtering target made of tin oxide and unavoidable impurities, the SnO ₂ powder and _In 2 _{O 3} powder, with Sn / (In + Sn) atomic ratio, 1.8% The ratio is adjusted so as to be 3.7% or less (excluding 3.7%) and mixed, and sintering is performed in an oxygen atmosphere while maintaining the maximum sintering temperature at 1450 ° C. or less. .
When the indium oxide-tin oxide based oxide (ITO) sintered body target of the present invention is manufactured, it can be produced by a process of mixing, pulverizing, molding and sintering each raw material powder. As the raw material powder, it is desirable to use indium oxide powder and tin oxide powder having a specific surface area of about 5 m ² / g.

Specifically, the indium oxide powder has a bulk density of 0.3 to 0.8 g / cm ³ , a median diameter (D ₅₀ ) of 0.5 to 2.5 μm, and a specific surface area of 3.0 to 6.0 m ^2. / G, tin oxide powder: bulk density: 0.2 to 0.6 g / cm ³ , median diameter (D ₅₀ ): 1.0 to 2.5 μm, specific surface area: 3.0 to 6.0 m ² / g use.

Each raw material powder is weighed so as to have a desired composition ratio, and then mixed and ground. There are various pulverization methods depending on the desired particle size and the material to be pulverized, but a wet medium stirring mill such as a bead mill is suitable. In this method, a slurry in which powder is dispersed in water is forcibly stirred together with a grinding medium such as zirconia or alumina, which is a material with high hardness, and a pulverized powder can be obtained with high efficiency. However, since the pulverizing medium is also worn at this time, the pulverizing medium itself is mixed as an impurity in the pulverized powder.

If the pulverization amount is defined by the difference in specific surface area before and after pulverization, the pulverization amount is almost proportional to the input energy to the powder in the wet medium stirring mill. Therefore, when performing pulverization, it is important that the wet medium stirring mill manages the integrated power. The difference in specific surface area before and after pulverization (ΔBET) is 0.5 to 5.0 m ² / g, and the median diameter (D ₅₀ ) after pulverization is 2.5 μm or less.

Next, the finely pulverized slurry is granulated. This is because by improving the fluidity of the powder by granulation, the powder is uniformly filled in the mold at the time of press molding in the next step, and a homogeneous molded body is obtained. There are various types of granulation, and one method for obtaining granulated powder suitable for press molding is a method using a spray-type drying device (spray dryer). This is a method in which powder is dispersed as slurry in hot air and dried instantaneously, and spherical granulated powder of 10 to 500 μm can be continuously obtained.

Moreover, a molded object intensity | strength can be improved by adding binders, such as polyvinyl alcohol (PVA), in a slurry, and making it contain in granulated powder. The amount of PVA added was PVA 4 to 10 wt. % Of the aqueous solution containing 50 to 250 cc / kg of the raw material powder.

Furthermore, the crushing strength of the granulated powder during press molding can be adjusted by adding a plasticizer suitable for the binder. There is also a method for improving the strength of the molded body by adding a small amount of water to the obtained granulated powder to wet it. In drying with a spray dryer, it is important to control the inlet temperature and outlet temperature of hot air.

If the temperature difference between the inlet and outlet is large, the amount of drying per unit time will increase and the productivity will improve, but if the inlet temperature is too high, the powder and added binder will change in quality due to heat, and the desired characteristics May not be obtained. In addition, when the outlet temperature is too low, the granulated powder may not be sufficiently dried.

Next, press molding is performed. The granulated powder is filled into a mold and molded by holding a pressure of 400 to 1000 kgf / cm ² for 1 to 3 minutes. When the pressure is less than 400 kgf / cm ² , a molded body having sufficient strength and density cannot be obtained. When the pressure is 1000 kgf / cm ² or more, the molded body itself is out of pressure when taken out from the mold. It may break due to deformation due to being released, which is not preferable in production.

Using an electric furnace, the molded body is sintered in an oxygen atmosphere to obtain a sintered body. Sintering is performed at a sintering temperature of 1450 ° C. or lower. In this case, if the sintering temperature exceeds 1450 ° C., the structure of the sintered body becomes a single phase and the crystal grain size becomes coarse, so the upper limit is preferably set to 1450 ° C. A binder removal step or the like may be introduced as needed during the temperature rise to the sintering temperature.

If the holding time at the sintering temperature is shorter than 2 hours, the sintering does not proceed sufficiently, and the density of the sintered body does not increase sufficiently, or the sintered body warps. Even if the holding time exceeds 100 hours, unnecessary energy and time is wasted, which is not preferable for production. Preferably, it is 5 to 20 hours.
The atmosphere during cooling when the temperature is lowered is an air atmosphere or an oxygen atmosphere, and is maintained at a temperature lower than the maximum holding temperature of 100 ° C. ± 20 ° C. for about 1 hour, so that 95% or more of the tin oxide rich phase exists at the grain boundary triple point can do. This is because solid solution of Sn precipitates during cooling, and by maintaining at a low temperature of 100 ° C. ± 20 ° C., 95% or more of the tin oxide rich phase should be present at the grain boundary triple point. Is possible. The holding time may be 1 hour or longer, but no significant change is observed. This holding time can be appropriately adjusted in consideration of the holding temperature and the like, and is not particularly limited as long as a desired structure is obtained.

The bulk resistivity can be measured using, for example, NP-5, model: Σ-5 +. In the measurement, first, four metal probes are placed on a straight line on the surface of the sample, a constant current is passed between the two outer probes, the potential difference generated between the two inner probes is measured, and the resistance is obtained. A volume resistivity (bulk resistivity) can be calculated by multiplying the obtained resistance by a sample thickness and a correction coefficient RCF (Resistency Correction Factor).

As described above, the sintered body sintered under these conditions has a sintered body density of 7.03 g / cm ³ or higher, a bulk resistivity of 0.10 to 0.15 mΩ · cm, It is possible to improve conductivity. Further, the maximum size of the tin oxide rich phase can be set to 1 μm, and the target can be prevented from being coarsened.
Moreover, the strength of the target can be increased by setting the bending strength of the sintered body of the ITO sputtering target to 100 MPa or more.

The surface of the sintered body thus obtained is ground, and the side is further cut into a size of 127 mm × 508 mm with a diamond cutter.
Next, an oxygen-free copper backing plate is placed on a hot plate set at 200 ° C., and indium is used as a brazing material, and the thickness is applied to be about 0.2 mm. An ITO sintered body is bonded onto the backing plate and allowed to cool to room temperature.

This target was attached to a SYNCHRON magnetron sputtering system (BSC-7011), the input power was 2.3 W / cm ² with a DC power source, the gas pressure was 0.6 Pa, and the sputtering gas was argon (Ar) and oxygen (O ₂ ). Film formation is performed with a total gas flow rate of 300 sccm and an oxygen concentration of 0 to 4%.
In particular, in the production of the transparent conductive film of the present invention, the substrate is not heated or maintained at 150 ° C. or less in a mixed gas atmosphere composed of argon and oxygen and having an oxygen concentration of 4% or less, and the ITO sputtering of the present invention is performed. It is preferable to form a film on a substrate using a target. The substrate may be not only a glass substrate but also a film substrate such as PET.

The transparent conductive film thus prepared is a transparent conductive film made of In, Sn, O, and inevitable impurities, and Sn / (In + Sn) is 1.8% or more and 3.7% or less (by atomic ratio). However, it contains Sn that is not 3.7%), the resistivity of the film in non-heated film formation is 3.0 mΩ · cm or less, and the transmittance at a wavelength of 550 nm is 80% or more. A transparent conductive film can be obtained.
Further, a transparent conductive film containing Sn having an atomic ratio of Sn / (In + Sn) of 2.3 to 3.2% and including In, Sn, O, and unavoidable impurities may be used. Thus, the produced transparent conductive film can be made into crystallization temperature 120 degrees C or less.

Next, terms (definitions, test methods, etc.) used in this specification will be described.
First, the observed part of the target is divided into four equal parts, the central part of the four equally divided sintered bodies is two visual fields, and the total eight visual fields are the observed parts. A specific example of the observation location is indicated by ● in FIG. The upper left figure in FIG. 4 shows a round sintered body, the right figure in FIG. 4 shows a square sintered body, and the lower left figure in FIG. 4 shows a cylindrical type.
(Measuring method of average grain size of sintered body)
The code method was used as a method for measuring the average crystal grain size. In the code method, a straight line is drawn from a grain boundary to a grain boundary in an arbitrary direction on an SEM image of x2,000 times, and the average of the length of the line crossing one particle is defined as an average crystal grain size. An arbitrary straight line (from the grain boundary to the grain boundary) is drawn on the SEM image (photograph), the number of intersections with the grain boundary is counted, and the following (Formula 1) is calculated.
(Equation 1) Average crystal grain size = length of straight line / number of intersections Specifically, five parallel lines of arbitrary length are drawn per SEM image of 8 fields per field, and the total length of the lines The average crystal grain size was calculated from the average of the total number of intersections between the grain boundaries.
The sample was etched with aqua regia after mirror polishing. The SEM images were taken with FE-EPMA (JXA-8500F type FE electron probe microanalyzer manufactured by JEOL Ltd.).

(Hole area ratio)
The vacancies were observed using a SEM image of x2,000 times. The holes have a substantially circular shape (including a perfect circle), an elliptical shape, and a distorted circular shape, and each of the largest diameter portion and the major axis diameter (including the diameter) were measured. The pore area ratio was determined from the histogram using the SEM image of 8 fields of x2,000 magnification, after grayscale / binarization processing in Adobe Photoshop Elements 7.0, from the histogram (average area of 8 fields of view) Ratio) was calculated. The sample was etched with aqua regia after mirror polishing. The SEM images were taken with FE-EPMA (JXA-8500F type FE electron probe microanalyzer manufactured by JEOL Ltd.).

(About tin oxide rich phase)
FIG. 1 is based on FE-EPMA (JXA-8500F type FE electron probe microanalyzer manufactured by JEOL Ltd.) of an ITO sintered body containing Sn with an atomic ratio of Sn / (In + Sn) of 3.8%. Although it is a surface analysis result of Sn x2000 times, a tin oxide rich phase refers to a phase (white part in an image) whose Sn intensity is stronger than other phases.
As for the area ratio of the tin oxide rich phase, Sn field analysis images of 50 μm × 50 μm were taken with 8 visual fields, and after the gray scale / binarization treatment with Adobe Photoshop Elements 7.0, the area ratio of the tin oxide rich phase from the histogram (8 visual fields) Average area ratio).
The left side of FIG. 1 is a diagram (image) showing the analysis result of the Sn plane of an ITO sintered body containing Sn with an atomic ratio of Sn / (In + Sn) of 3.8%, and the right side is an SEM image. FIG.
The maximum size of the tin oxide-rich phase refers to the maximum major axis diameter in the image 8 field of view.

(Indium oxide phase)
A phase other than the tin oxide rich phase in the Sn plane analysis result of FIG. 1 is defined as an indium oxide phase.

(Explanation regarding the presence of 95% or more of tin oxide rich phase at grain boundary triple point)
Grain boundary triple point: A in FIG. 2 is an SEM image of an ITO sintered body containing 2.8% Sn / (In + Sn) in atomic ratio, and a line is drawn along the grain boundary in FIG. And it becomes like B of FIG. The grain boundary triple point refers to the intersection of the grain boundaries of three grains, as indicated by the ● portion in B of FIG. A circled portion B in FIG. 2 indicates a portion that is not a grain boundary triple point.
C in FIG. 2 is an Sn surface analysis result in the same field of view as A in FIG. 2, and a portion surrounded by a round dotted line is a tin oxide rich phase. 2C is overlapped with A in FIG. 2 to confirm whether the tin oxide rich phase is located at the grain boundary triple point, and the number of tin oxide rich phases and the tin oxide rich phase located at the grain boundary triple point. Confirm that the ratio of the number is 95% or more in all 8 fields of view. 2D is an SEM image obtained by superimposing A in FIG. 2 and C in FIG.

(Sintered body bending strength test method)
The test was conducted in accordance with the three-point bending test of the bending strength (JIS R 1601) of fine ceramics. There are 20 test pieces, and the numerical values described are average values. The equipment used is Imada Tensile and Compression Tester (SV-201NA-50SL type).

(Arcing detection sensitivity)
The number of arcing (micro arc) occurrences (times) was measured with a micro arc monitor (MAM Genesis) manufactured by Landmark Technology. The arcing criteria were as follows: arcing with a detection voltage of 100 V or more and emission energy (sputtering voltage when sputtering occurred × sputtering current × generation time) of 20 mJ or less was counted.

(Nodule coverage)
FIG. 3 is a photograph of a target after 35 hours of continuous sputtering. A white dotted line frame is photographed with a digital camera, and after gray scale / binarization processing (see FIG. 3) at Adobe Photoshop Elements 7.0, nodules are obtained from the histogram. The area ratio was calculated, and the average of the three locations was defined as the nodule coverage.

Hereinafter, the present invention will be described based on examples and comparative examples. However, these examples and comparative examples are for ease of understanding, and the present invention is not limited by these examples. Absent. That is, modifications and other embodiments based on the technical idea of the present invention are naturally included in the present invention.

(Example 1)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.8% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 5 hours. Then, it hold | maintained at 1350 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.070 g / cm ³ , a bending strength of 115 MPa, a bulk resistivity of 0.110 mΩ · cm, an average crystal grain size of 3.43 μm, and an area ratio of a tin oxide-rich phase of 0.7. It was 45%, the tin oxide rich phase triple point existence probability was 98%, and the hole area ratio was 0.08%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 28 times / 24 hr, and the nodule coverage was as good as 1%.
The results are shown in Table 1.

(Example 2)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.8% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1330 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.100 g / cm ³ , a bending strength of 120 MPa, a bulk resistivity of 0.116 mΩ · cm, an average crystal grain size of 3.54 μm, and a tin oxide-rich phase area ratio of 0.1. It was 39%, the tin oxide rich phase triple point existence probability was 99%, and the hole area ratio was 0.07%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of arcing occurrences was 23/24 hr, and the nodule coverage was as good as 0.8%.

In Example 2, the same DC power density and gas pressure were used, and argon was used as the sputtering gas, the oxygen content was 0, 1, 2, 4%, and the glass substrate (EagleXG) was formed without heating at a gas flow rate of 300 sccm. A 40 nm ITO film was prepared.
This membrane is heated to 50 to 200 ° C. in an air atmosphere for 60 minutes using an inert oven furnace (model number: INL-45-S), and the film before and after heating is XRD (apparatus model: Rigaku_Fully Automatic Horizontal Model) Multi-purpose X-ray diffractometer (SmartLab) measurement confirmed the presence or absence of crystallization. The crystallization temperature was a temperature at which the peak of the (222) plane of In ₂ O ₃ was observed by XRD measurement.

When the oxygen concentration was 0%, the film resistivity was 2.70 mΩ · cm, the transmittance at a wavelength of 500 nm was 80.5%, and the crystallization temperature was 100 ° C.
When the oxygen concentration was 1%, the film resistivity was 1.01 mΩ · cm, the transmittance at a wavelength of 500 nm was 84.0%, and the crystallization temperature was 100 ° C.
When the oxygen concentration was 2%, the film resistivity was 0.59 mΩ · cm, the transmittance at a wavelength of 500 nm was 88.1%, and the crystallization temperature was 100 ° C.
When the oxygen concentration was 4%, the film resistivity was 0.81 mΩ · cm, the transmittance at a wavelength of 500 nm was 87.4%, and the crystallization temperature was 100 ° C.
The results are shown in Table 2. In either case, good results were obtained.

(Example 3)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.8% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 15 hours. Then, it hold | maintained at 1370 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.105 g / cm ³ , a bending strength of 121 MPa, a bulk resistivity of 0.124 mΩ · cm, an average crystal grain size of 3.66 μm, and a tin oxide-rich phase area ratio of 0.1. 35%, tin oxide rich phase triple point existence probability 99%, pore area ratio was 0.05%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 20 times / 24 hr, and the nodule coverage was as good as 0.3%.

Example 4
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.8% in terms of atomic ratio. The maximum sintering temperature was 1430 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1330 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.082 g / cm ³ , a bending strength of 116 MPa, a bulk resistivity of 0.118 mΩ · cm, an average crystal grain size of 3.26 μm, and an area ratio of a tin oxide-rich phase of 0. It was 68%, the tin oxide rich phase triple point existence probability was 99%, and the hole area ratio was 0.10%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 25/24 hr, and the nodule coverage was as good as 0.7%.

(Example 5)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.8% in terms of atomic ratio. The maximum sintering temperature was 1400 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1300 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.058 g / cm ³ , a bending strength of 113 MPa, a bulk resistivity of 0.121 mΩ · cm, an average crystal grain size of 3.20 μm, and an area ratio of a tin oxide-rich phase of 0. It was 83%, the tin oxide rich phase triple point existence probability was 98%, and the pore area ratio was 0.15%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 31 times / 24 hr, and the nodule coverage was good at 1.2%.

(Example 6)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 1.8% in terms of atomic ratio. The maximum sintering temperature was 1350 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1250 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.036 g / cm ³ , a bending strength of 110 MPa, a bulk resistivity of 0.129 mΩ · cm, an average crystal grain size of 3.01 μm, and a tin oxide-rich phase area ratio of 0.001. It was 95%, the tin oxide rich phase triple point existence probability was 97%, and the hole area ratio was 0.23%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 40 times / 24 hr, and the nodule coverage was as good as 1.5%.

(Example 7)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 1.8% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1350 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.074 g / cm ³ , a bending strength of 111 MPa, a bulk resistivity of 0.131 mΩ · cm, an average crystal grain size of 3.96 μm, and a tin oxide-rich phase area ratio of 0.8. 21%, tin oxide-rich phase triple point existence probability was 99%, and the hole area ratio was 0.08%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 31 times / 24 hr, and the nodule coverage was as good as 0.9%.

For Example 7, argon was used as the sputtering gas with the same DC power density and gas pressure, the oxygen content was 0, 1, 2, and 4%, and the glass substrate (EagleXG) was formed without heating at a gas flow rate of 300 sccm. A 40 nm ITO film was prepared.
This membrane is heated to 50 to 200 ° C. in an air atmosphere for 60 minutes using an inert oven furnace (model number: INL-45-S), and the film before and after heating is XRD (apparatus model: Rigaku_Fully Automatic Horizontal Model) Multi-purpose X-ray diffractometer (SmartLab) measurement confirmed the presence or absence of crystallization. The crystallization temperature was a temperature at which the peak of the (222) plane of In ₂ O ₃ was observed by XRD measurement.

When the oxygen concentration was 0%, the film resistivity was 2.93 mΩ · cm, the transmittance at a wavelength of 500 nm was 81.1%, and the crystallization temperature was 80 ° C.
When the oxygen concentration was 1%, the film resistivity was 1.33 mΩ · cm, the transmittance at a wavelength of 500 nm was 83.2%, and the crystallization temperature was 80 ° C.
When the oxygen concentration was 2%, the film resistivity was 0.65 mΩ · cm, the transmittance at a wavelength of 500 nm was 88.7%, and the crystallization temperature was 80 ° C.
When the oxygen concentration was 4%, the film resistivity was 0.96 mΩ · cm, the transmittance at a wavelength of 500 nm was 86.9%, and the crystallization temperature was 80 ° C.
The results are also shown in Table 2. In either case, good results were obtained.

(Example 8)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 1.8% in terms of atomic ratio. The maximum sintering temperature was 1400 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1300 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.045 g / cm ³ , a bending strength of 107 MPa, a bulk resistivity of 0.125 mΩ · cm, an average crystal grain size of 3.46 μm, and an area ratio of a tin oxide-rich phase of 0. It was 26%, the tin oxide rich phase triple point existence probability was 99%, and the hole area ratio was 0.11%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 33 times / 24 hr, and the nodule coverage was good at 1.2%.

Example 9
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.1% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1350 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained, the sintered body density 7.079g / cm ^3, flexural strength 113MPa, bulk resistivity 0.125mΩ · cm, an average crystal grain size 3.55Myuemu, the area ratio of the tin oxide-rich phase 0. 18%, tin oxide-rich phase triple point existence probability was 99%, and the hole area ratio was 0.12%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 30 times / 24 hr, and the nodule coverage was as good as 1.3%.

(Example 10)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.1% in terms of atomic ratio. The maximum sintering temperature was 1400 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1300 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.050 g / cm ³ , a bending strength of 110 MPa, a bulk resistivity of 0.122 mΩ · cm, an average crystal grain size of 2.75 μm, and a tin oxide-rich phase area ratio of 0.7. It was 22%, the tin oxide rich phase triple point existence probability was 99%, and the hole area ratio was 0.13%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of arcing occurrences was 31 times / 24 hr, and the nodule coverage was as good as 1.6%.

(Example 11)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.6% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1350 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.088 g / cm ³ , a bending strength of 119 MPa, a bulk resistivity of 0.123 mΩ · cm, an average crystal grain size of 2.97 μm, and an area ratio of a tin oxide-rich phase of 0. 33%, tin oxide rich phase triple point existence probability was 98%, and the hole area ratio was 0.10%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 25 times / 24 hr, and the nodule coverage was as good as 1%.

Example 12
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.6% in terms of atomic ratio. The maximum sintering temperature was 1400 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1300 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.071 g / cm ³ , a bending strength of 115 MPa, a bulk resistivity of 0.119 mΩ · cm, an average crystal grain size of 2.83 μm, and a tin oxide-rich phase area ratio of 0.001. It was 38%, the tin oxide rich phase triple point existence probability was 98%, and the hole area ratio was 0.10%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 28 times / 24 hr, and the nodule coverage was as good as 1.1%.

(Example 13)
Sintering was carried out using SnO ₂ powder and In ₂ O ₃ powder, the ratio of which was adjusted so that Sn / (In + Sn) was 3.0% in terms of atomic ratio, in an oxygen atmosphere as a sintering raw material. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1350 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.103 g / cm ³ , a bending strength of 126 MPa, a bulk resistivity of 0.117 mΩ · cm, an average crystal grain size of 3.67 μm, and a tin oxide-rich phase area ratio of 0.1. The tin oxide rich phase triple point existence probability was 41%, and the pore area ratio was 0.08%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 21 times / 24 hr, and the nodule coverage was as good as 0.9%.

(Example 14)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 3.0% in terms of atomic ratio. The maximum sintering temperature was 1400 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1300 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.091 g / cm ³ , a bending strength of 121 MPa, a bulk resistivity of 0.115 mΩ · cm, an average crystal grain size of 3.49 μm, and a tin oxide-rich phase area ratio of 0.001. It was 46%, the tin oxide rich phase triple point existence probability was 98%, and the pore area ratio was 0.09%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 24 times / 24 hr, and the nodule coverage was as good as 0.9%.

(Example 15)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 3.2% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1350 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.109 g / cm ³ , a bending strength of 127 MPa, a bulk resistivity of 0.110 mΩ · cm, an average crystal grain size of 3.82 μm, and a tin oxide-rich phase area ratio of 0.1. 55%, the tin oxide rich phase triple point existence probability was 98%, and the hole area ratio was 0.07%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of arcing occurrences was 18 times / 24 hr, and the nodule coverage was as good as 0.7%.

For Example 15, the same DC power density and gas pressure, argon as the sputtering gas, oxygen content of 0, 1, 2, and 4%, gas flow rate of 300 sccm, and heating to the glass substrate (Eagle XG) without heating. A 40 nm ITO film was prepared.
This membrane is heated to 50 to 200 ° C. in an air atmosphere for 60 minutes using an inert oven furnace (model number: INL-45-S), and the film before and after heating is XRD (apparatus model: Rigaku_Fully Automatic Horizontal Model) Multi-purpose X-ray diffractometer (SmartLab) measurement confirmed the presence or absence of crystallization. Crystallization temperature and a temperature peak is observed in the _In 2 of _{O 3} (222) plane by XRD measurement.

When the oxygen concentration was 0%, the film resistivity was 2.65 mΩ · cm, the transmittance at a wavelength of 500 nm was 80.1%, and the crystallization temperature was 110 ° C.
When the oxygen concentration was 1%, the film resistivity was 0.97 mΩ · cm, the transmittance at a wavelength of 500 nm was 83.6%, and the crystallization temperature was 110 ° C.
When the oxygen concentration was 2%, the film resistivity was 0.60 mΩ · cm, the transmittance at a wavelength of 500 nm was 89.2%, and the crystallization temperature was 110 ° C.
When the oxygen concentration was 4%, the film resistivity was 0.84 mΩ · cm, the transmittance at a wavelength of 500 nm was 87.6%, and the crystallization temperature was 110 ° C.
The results are also shown in Table 2. In either case, good results were obtained.

(Example 16)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 3.2% in terms of atomic ratio. The maximum sintering temperature was 1400 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1300 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained has a sintered body density of 7.100 g / cm ³ , a bending strength of 123 MPa, a bulk resistivity of 0.104 mΩ · cm, an average crystal grain size of 3.77 μm, and a tin oxide-rich phase area ratio of 0.1. 62%, tin oxide-rich phase triple point existence probability was 98%, and the hole area ratio was 0.06%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of arcing occurrences was 18 times / 24 hr, and the nodule coverage was as good as 0.6%.

(Example 17)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 3.5% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1350 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.112 g / cm ³ , a bending strength of 130 MPa, a bulk resistivity of 0.111 mΩ · cm, an average crystal grain size of 4.02 μm, and a tin oxide-rich phase area ratio of 0.001. 62%, tin oxide-rich phase triple point existence probability was 98%, and the hole area ratio was 0.06%.
A target was prepared by using this sintered body, DC power density 2.3 W / cm ^2, the gas pressure is 0.6 Pa, the sputtering gas is argon (Ar), was subjected to a continuous 35 hours sputtering at a gas flow rate 300sccm However, the number of occurrences of arcing was 15 times / 24 hr, and the nodule coverage was as good as 0.6%.

(Example 18)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 3.5% in terms of atomic ratio. The maximum sintering temperature was 1400 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it kept at 1300 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained has a sintered body density of 7.102 g / cm ³ , a bending strength of 128 MPa, a bulk resistivity of 0.106 mΩ · cm, an average crystal grain size of 3.89 μm, a tin oxide-rich phase area ratio of 0.1. 70%, tin oxide-rich phase triple point existence probability was 97%, and the pore area ratio was 0.05%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 14 times / 24 hr, and the nodule coverage was good at 0.5%.

(Comparative Example 1)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.8% in terms of atomic ratio. The maximum sintering temperature was 1550 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1450 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.112 g / cm ³ , a bending strength of 122 MPa, a bulk resistivity of 0.135 mΩ · cm, an average crystal grain size of 7.64 μm, and a tin oxide-rich phase area ratio of 0.1. 00%, tin oxide-rich phase triple point existence probability was 0%, and the hole area ratio was 0.52%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 120 times / 24 hr, and the nodule coverage was 2.5%, which was not satisfactory because the conditions of the present invention were not satisfied.

(Comparative Example 2)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.8% in terms of atomic ratio. The maximum sintering temperature was 1500 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1400 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.106 g / cm ³ , a bending strength of 120 MPa, a bulk resistivity of 0.124 mΩ · cm, an average crystal grain size of 5.98 μm, and a tin oxide-rich phase area ratio of 0.8. 02%, tin oxide-rich phase triple point existence probability was 99%, and the hole area ratio was 0.68%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 148 times / 24 hr, and the nodule coverage was 3.1%, which did not satisfy the conditions of the present invention, and was unsatisfactory.

(Comparative Example 3)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.8% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 1 hour. Then, it hold | maintained at 1350 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 6.989 g / cm ³ , a bending strength of 103 MPa, a bulk resistivity of 0.121 mΩ · cm, an average crystal grain size of 3.25 μm, and a tin oxide-rich phase area ratio of 0.1. 58%, tin oxide-rich phase triple point existence probability was 94%, and the hole area ratio was 0.20%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 334 times / 24 hr, and the nodule coverage was 4.8%.

(Comparative Example 4)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 1.8% in terms of atomic ratio. The maximum sintering temperature was 1550 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1450 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.098 g / cm ³ , a bending strength of 115 MPa, a bulk resistivity of 0.125 mΩ · cm, an average crystal grain size of 6.21 μm, and an area ratio of tin oxide-rich phase of 0. 00%, tin oxide-rich phase triple point existence probability was 0%, and the pore area ratio was 0.55%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 100 times / 24 hr, and the nodule coverage was 2.6%, which did not satisfy the conditions of the present invention and was defective.

(Comparative Example 5)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 1.8% in terms of atomic ratio. The maximum sintering temperature was 1500 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1400 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.066 g / cm ³ , a bending strength of 111 MPa, a bulk resistivity of 0.120 mΩ · cm, an average crystal grain size of 5.12 μm, and a tin oxide-rich phase area ratio of 0.1. 00%, tin oxide-rich phase triple point existence probability was 0%, and the hole area ratio was 0.63%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 114 times / 24 hr, and the nodule coverage was 2.9%, which was not satisfactory because the conditions of the present invention were not satisfied.

(Comparative Example 6)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 1.6% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1350 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.048 g / cm ³ , a bending strength of 103 MPa, a bulk resistivity of 0.133 mΩ · cm, an average crystal grain size of 4.05 μm, and a tin oxide-rich phase area ratio of 0.005. 00%, tin oxide-rich phase triple point existence probability was 0%, and the hole area ratio was 0.62%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 128 times / 24 hr, and the nodule coverage was 2.9%, which did not satisfy the conditions of the present invention and was defective.

(Comparative Example 7)
Sn / (In + Sn) in atomic ratio was sintered in an oxygen atmosphere using a SnO ₂ powder and _In 2 _{O 3} powder was adjusted ratio such that 1.6% as a sintering material. The maximum sintering temperature was 1400 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1300 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.024 g / cm ³ , a bending strength of 98 MPa, a bulk resistivity of 0.138 mΩ · cm, an average crystal grain size of 3.83 μm, and a tin oxide-rich phase area ratio of 0.8. 02%, tin oxide-rich phase triple point existence probability was 99%, and the hole area ratio was 0.66%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 145 times / 24 hr, and the nodule coverage was 3.3%, which did not satisfy the conditions of the present invention and was defective.

(Comparative Example 8)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratio was adjusted so that Sn / (In + Sn) was 1.4% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1350 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.030 g / cm ³ , a bending strength of 99 MPa, a bulk resistivity of 0.139 mΩ · cm, an average crystal grain size of 4.68 μm, and a tin oxide-rich phase area ratio of 0.8. 00%, tin oxide-rich phase triple point existence probability was 0%, and the pore area ratio was 0.78%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 138 times / 24 hr, and the nodule coverage was 3.2%, which did not satisfy the conditions of the present invention, and was unsatisfactory.

For this comparative example 8, with the same DC power density and gas pressure, the sputtering gas was argon, the oxygen content was 0, 1, 2, 4%, the gas flow rate was 300 sccm, and the glass substrate (EagleXG) was not heated. A 40 nm ITO film was prepared.
This membrane is heated to 50-200 ° C in an air atmosphere for 60 minutes using an inert gas oven furnace (model number: INL-45-S), and the film before and after heating is XRD (apparatus model number: manufactured by Rigaku_fully automatic horizontal type) The presence or absence of crystallization was confirmed by multipurpose X-ray diffractometer SmartLab) measurement. The crystallization temperature was a temperature at which the peak of the (222) plane of In ₂ O ₃ was observed by XRD measurement.

When the oxygen concentration was 0%, the film resistivity was 6.21 mΩ · cm, the transmittance at a wavelength of 500 nm was 72.9%, and the crystallization temperature was 50 ° C.
When the oxygen concentration was 1%, the film resistivity was 4.60 mΩ · cm, the transmittance at a wavelength of 500 nm was 76.3%, and the crystallization temperature was 50 ° C.
When the oxygen concentration was 2%, the film resistivity was 3.01 mΩ · cm, the transmittance at a wavelength of 500 nm was 78.7%, and the crystallization temperature was 50 ° C.
When the oxygen concentration was 4%, the film resistivity was 4.38 mΩ · cm, the transmittance at a wavelength of 500 nm was 75.4%, and the crystallization temperature was 50 ° C.
The results are also shown in Table 2. In either case, the conditions satisfying the present invention were satisfied.

(Comparative Example 9)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratio was adjusted so that Sn / (In + Sn) was 1.4% in terms of atomic ratio. The maximum sintering temperature was 1400 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1300 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.015 g / cm ³ , a bending strength of 90 MPa, a bulk resistivity of 0.145 mΩ · cm, an average crystal grain size of 4.07 μm, and a tin oxide-rich phase area ratio of 0.005. 00%, tin oxide-rich phase triple point existence probability was 0%, and the hole area ratio was 0.85%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 162 times / 24 hr, and the nodule coverage was 3.5%, which did not satisfy the conditions of the present invention and was defective.

(Comparative Example 10)
Sintering was performed in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratio was adjusted so that Sn / (In + Sn) was 1.2% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1350 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained, the sintered body density 7.009g / cm ^3, flexural strength 88 MPa, a bulk resistivity of 0.148mΩ · cm, an average crystal grain size 5.03Myuemu, the area ratio of the tin oxide-rich phase 0. 00%, tin oxide-rich phase triple point existence probability was 0%, and the hole area ratio was 0.88%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 173 times / 24 hr, and the nodule coverage was 3.8%, which did not satisfy the conditions of the present invention and was defective.

(Comparative Example 11)
Sintering was performed in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratio was adjusted so that Sn / (In + Sn) was 1.2% in terms of atomic ratio. The maximum sintering temperature was 1400 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1300 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 6.994 g / cm ³ , a bending strength of 80 MPa, a bulk resistivity of 0.156 mΩ · cm, an average crystal grain size of 4.54 μm, and a tin oxide-rich phase area ratio of 0.1. 00%, tin oxide-rich phase triple point existence probability was 0%, and the hole area ratio was 1.02%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 199 times / 24 hr, and the nodule coverage was 1.3%.

(Comparative Example 12)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 3.7% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1350 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.112 g / cm ³ , a bending strength of 120 MPa, a bulk resistivity of 0.120 mΩ · cm, an average crystal grain size of 4.32 μm, and an area ratio of a tin oxide rich phase. The tin oxide rich phase triple point existence probability was 92% and the pore area ratio was 0.22%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 60 times / 24 hr, and the nodule coverage was 1.3%, which did not satisfy the conditions of the present invention, and was defective.

For this Comparative Example 12, the same DC power density and gas pressure were used, and the sputtering gas was argon, the oxygen content was 0, 1, 2, 4%, and the glass substrate (EagleXG) was heated without heating at a gas flow rate of 300 sccm. A 40 nm ITO film was prepared.
This film was heated to 50 to 200 ° C. in an air atmosphere for 60 minutes using an inert gas oven furnace (model number: INL-45-S), and the film before and after heating was XRD (apparatus model: Rigaku_Fully Automatic Horizontal Model) The presence or absence of crystallization was confirmed by multipurpose X-ray diffractometer SmartLab) measurement. The crystallization temperature was a temperature at which the peak of the (222) plane of In ₂ O ₃ was observed by XRD measurement.

When the oxygen concentration was 0%, the film resistivity was 2.74 mΩ · cm, the transmittance at a wavelength of 500 nm was 77.1%, and the crystallization temperature was 130 ° C.
When the oxygen concentration was 1%, the film resistivity was 0.99 mΩ · cm, the transmittance at a wavelength of 500 nm was 84.6%, and the crystallization temperature was 130 ° C.
When the oxygen concentration was 2%, the film resistivity was 0.61 mΩ · cm, the transmittance at a wavelength of 500 nm was 86.8%, and the crystallization temperature was 130 ° C.
When the oxygen concentration was 4%, the film resistivity was 0.87 mΩ · cm, the transmittance at a wavelength of 500 nm was 85.1%, and the crystallization temperature was 130 ° C.
The results are also shown in Table 2. In either case, the conditions satisfying the present invention were satisfied.

(Comparative Example 13)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.8% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Thereafter, the temperature was lowered and cooled without being maintained at a specific temperature. The sintered body thus obtained had a sintered body density of 7.093 g / cm ³ , a bending strength of 110 MPa, a bulk resistivity of 0.110 mΩ · cm, an average crystal grain size of 3.55 μm, and an area ratio of a tin oxide-rich phase of 0. The tin oxide rich phase triple point existence probability was 91% and the pore area ratio was 0.07%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 156 times / 24 hr, and the nodule coverage was 2.0%, which was not satisfactory because the conditions of the present invention were not satisfied.

(Comparative Example 14)
Sintering was carried out in an oxygen atmosphere using SnO ₂ powder and In ₂ O ₃ powder whose ratios were adjusted so that Sn / (In + Sn) was 2.8% in terms of atomic ratio. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1250 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.095 g / cm ³ , a bending strength of 115 MPa, a bulk resistivity of 0.123 mΩ · cm, an average crystal grain size of 3.58 μm, and a tin oxide-rich phase area ratio of 0.1. It was 08%, the tin oxide rich phase triple point existence probability was 92%, and the hole area ratio was 0.06%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 140 times / 24 hr, and the nodule coverage was 2.2%, which did not satisfy the conditions of the present invention and was defective.

(Comparative Example 15)
Sn / (In + Sn) in atomic ratio was sintered in an oxygen atmosphere using a SnO ₂ powder and _In 2 _{O 3} powder was adjusted ratio such that 2.8% as a sintering material. The maximum sintering temperature was 1450 ° C., and the holding time at the maximum sintering temperature was 10 hours. Then, it hold | maintained at 1400 degreeC for 1 hour at the time of temperature-fall cooling. The sintered body thus obtained had a sintered body density of 7.100 g / cm ³ , a bending strength of 120 MPa, a bulk resistivity of 0.136 mΩ · cm, an average crystal grain size of 3.65 μm, and a tin oxide-rich phase area ratio of 0.1. 05%, tin oxide-rich phase triple point existence probability 90%, pore area ratio was 0.07%.
A target was prepared using this sintered body, and sputtering was performed continuously at a DC power density of 2.3 W / cm ² , a gas pressure of 0.6 Pa, a sputtering gas of argon (Ar), and a gas flow rate of 300 sccm for 35 hours. However, the number of occurrences of arcing was 230 times / 24 hr, and the nodule coverage was 2.6%, which did not satisfy the conditions of the present invention and was defective.

Regarding the film resistivity, the transmittance at a wavelength of 500 nm, and the crystallization temperature when the oxygen concentration is changed in the above-described examples and comparative examples, the comparison is made between the example 2, the example 7, the example 15, and the comparison. Although Example 8 and Comparative Example 12 were described and other examples and comparative examples were omitted, this is for the purpose of avoiding complexity, and it is added that similar results are obtained.

The present invention relates to an ITO sputtering target having a low tin oxide composition suitable for forming a transparent conductive film and capable of obtaining a low resistance film even at a low temperature, and has a small target particle size, high density, and high strength. An ITO sputtering target capable of reducing arcing and nodules can be provided.
In addition, it is possible to reduce the change in film characteristics accompanying the progress of sputtering and to improve the quality of film formation. As a result, there is an excellent effect that the productivity and reliability of the ITO target can be improved. The ITO sputtering target of the present invention is particularly useful for forming an ITO film and is optimal for applications such as a touch panel, a flat panel display, an organic EL, and a solar cell.

Claims

A sintered body composed of In, Sn, O, and inevitable impurities, and Sn / (In + Sn) is 1.8% or more and 3.7% or less (excluding 3.7%) by atomic ratio. The average crystal grain size of the sintered body is in the range of 1.0 to 5.0 μm, and the pores with the major axis diameter of 0.1 to 1.0 μm are 0.5% or less in area ratio. The indium oxide phase and the tin oxide rich phase are two phases. The area ratio of the tin oxide rich phase is 0.1 to 1.0% or less, and 95% or more of the tin oxide rich phase is at the grain boundary triple point. A sputtering target characterized in that it exists.
2. The sputtering target according to claim 1, comprising Sn having an atomic ratio of Sn / (In + Sn) of 2.3 to 3.2%.
The sputtering target according to claim 1 or 2, wherein the sintered body has a density of 7.03 g / cm 3 or more and a bulk resistivity of 0.10 to 0.15 mΩ · cm.
The sputtering target according to any one of claims 1 to 3, wherein the maximum size of the tin oxide-rich phase is 1 µm or less.
The sputtering target according to any one of claims 1 to 4, wherein the bending strength is 100 MPa or more.
A method for producing a sputtering target comprising In, Sn, O, and inevitable impurities, wherein Sn / (In + Sn) is 1.8% or more and 3.7% in terms of atomic ratio of SnO 2 powder and In 2 O 3 powder. The ITO is characterized in that the ratio is adjusted so as to be (except 3.7%), and the mixture is sintered, and sintered under an oxygen atmosphere while maintaining the maximum sintering temperature at a temperature of 1450 ° C. or lower. A method for producing a sputtering target.
The SnO 2 powder and the In 2 O 3 powder are mixed and sintered by adjusting the ratio so that Sn / (In + Sn) is 2.3 to 3.2% in atomic ratio. 6. A method for producing a sputtering target according to 6.
The method for producing a sputtering target according to claim 6 or 7, wherein in the cooling step after sintering, the temperature is held at a temperature lower by 100 ° C ± 20 ° C than the sintering holding temperature.
A transparent conductive film composed of In, Sn, O, and inevitable impurities, and Sn / (In + Sn) is 1.8% or more and 3.7% or less (except 3.7%) in atomic ratio. A transparent conductive film characterized by containing Sn and having a film characteristic of having a film resistivity of 3.0 mΩ · cm or less in non-heated film formation and having a transmittance of 80% or more at a wavelength of 550 nm.
10. The transparent conductive film according to claim 9, comprising Sn with an atomic ratio of Sn / (In + Sn) of 2.3 to 3.2%.
The transparent conductive film according to claim 9 or 10, wherein the crystallization temperature is 120 ° C or lower.
A method for producing a transparent conductive film by sputtering, wherein the substrate is not heated or maintained at 150 ° C. or less in a mixed gas atmosphere comprising argon and oxygen and having an oxygen concentration of 4% or less, A method for producing a transparent conductive film, comprising forming a film on a substrate using the sputtering target according to any one of the above items.